abstract : international journal of recent technology and engineering (ijrte) issn: - , volume- issue- , november retrieval number: c / ©beiesp doi: . /ijrte.c . published by: blue eyes intelligence engineering & sciences publication abstract:future decade’s energy industries and startups can go for an innovation method of electricity generation using clean power mechanism by using the renewable energy and by utilizing the abundant biomass wastes resources like husks, shells, powdery agri wastes, bagasse as fuels. similarity to fossil resources, biofuels for heat power utility and electricity production benefits higher efficiency without environmental impact. bio-oil extracted from biomass, is a carbon di oxide neutral technique and it will leads to credit among various resources of biomass coconuts are the surplus available source in the globe. literature shows that research investigation in extracting the by product from coconut using pyrolysis is very limited. the objective of present work is to envisage the research methods for generating power from coconut shell using pyrolysis. bio-oil extracted from pyrolysis process can be used as a fuel for oil burners and in boilers for heat and power applications. also bio-oil can be blended at proper proportion with diesel to bio- diesel fuel. hence pyrolysis based fuel extraction techniques are key solution to solve energy shortage in a friendly way using coconut shells. index terms: coconut shells, green energy, biomass, pyrolysis. i. introduction biomass is a hydrocarbon material consisting of carbon, hydrogen, oxygen, nitrogen and other components in small proportions. the use of the residual biomass as energy resource finds its typical applications from small ovens to boilers for both thermal and power applications. the thermo chemical processes of converting carbonaceous biomass are termed as combustion, pyrolysis and gasification [ ]. the pyrolysis technique is an innovated energy conversion mechanism which is capable to produce cleaner, higher calorific gas from a diversified range of biomass. pyrolysis technique products includes gases, vapor that can be separated as a liquid and solid char. solid char consists of a small amount of volatile hydrocarbons, solid hydrocarbons, and inorganic compounds [ ]. it involves the simultaneous change of chemical composition and physical phase, and is irreversible. the thermal treatment of coconut shells is accompanied by physicochemical and structural transformations. the calorific value and other elemental analysis of the coconut shell obtained from open literature are tabulated below. revised manuscript received on november , . sasikumar.c, department of mechanical bannari amman institute of technology (bit), sathyamangalam- . sundaresan. r , college of applied industrial technology, jazan university, baish, saudi arabia. *nagaraja. m, department of mechanical, psnacet, dindigul- . sivahari shankar ms. department of mechanical, psnacet, dindigul- . karthikeyan. s department of mechanical, psnacet, dindigul- . table . proximate & ultimate analysis of coconutshell [ ] [ ] [ ] proximate volatiles fixed carbon ash ultimate analysis (%) carbon hydrogen oxygen nitrogen sulphur moisture content . % . % . % . % . % . % . % . % . % . % . % . % . % . % . % . % . % . % . % . % . % . % . % . % . % . % calorific value(mj/kg) . . . pyrolysis experiments have been conducted by e. ganapathy sundaram et.al [ ] using coconut shell at pyrolysis temperature between and °c with particle size of . mm - . mm. the gas yield and liquid yield were reported to be increased from to wt% and to wt%, for a raise in operating temperature from to °c. mohammad uzzal hossain joardder et.al [ ] experimentally demonstrated the conversion of coconut shell into pyrolytic oil. the maximum oil yield of . wt% was achieved at a temperature of c for fuel size of . mm. experimental results shows that yield of liquid was reported to be increased to maximum at c and decreased at an operating temperature of c.[ ] reported that yield is maximum due to cracking of the coconut shells at this operating temperature. ii. process flow diagram the schematic diagram of bio-oil extraction process, various subsystems and bio-oil applications are as shown in figure. , figure. , figure. , figurre. and figure. figure .schematic view of a pyrolyser bio-oil from coconut shells sasikumar . c, sundaresan . r , nagaraja . m, sivahari shankar.m.s , karthikeyan . s bio-oil from coconut shells retrieval number: c / ©beiesp doi: . /ijrte.c . published by: blue eyes intelligence engineering & sciences publication figure .application of liquid bio-oil. l. fagbemi et.al [ ] envisaged the pyrolysis of wood, coconut shell and straw in a pyrolysis reactor of . m length and cm diameter. the pyrolyzer is made up of quartz tube, heated by a cylindrical oven. experimental results show that higher pyrolysis temperature favored the production of h .also gradual decrease in temperature decreases the co concentration with an increase in concentration of co. for coconut shell an increase in temperature from c to c the h content was reported to be increased from . % to . %. at an operating temperature of c the content of h reported for coconut shell is . %. this is higher than h composition reported for wood pyrolysis which is only . % at c. [ ]. also increase in temperature above c is found to favor the concentration of co. the co concentration for coconut shell is . % and woodchips is . % at c. [ ].the h concentration was also found to be higher at c with . % for coconut shell and . % for woodchips. coconut shell is also found to be an excellent ch generator than the wood. ch concentration was reported to be . % for coconut shell and . % for woodchips at c. figure .schematic view of bioprocess figure .schematic view cfb pyrolysis process figure .schematic view cfb pyrolysis process iii. results and discussions bio-oil derived from coconut shell has gcv ranging from - mj/kg which can be used for combustion in boiler and as an alternate fuel in diesel engine with some modification in engine. at higher temperatures above c thermal cracking of tars produces a purified syn gas rich in co and h , which can be used as feedstock for combustion in diesel engines.[ ] . v. f. olontsev et.al [ ] investigated that high carbonaceous charcoal can be extracted up on the pyrolysis of coconut shells with particle size of – mm. the optimum pyrolysis temperature of coconut shell is reported to be °c for maximizing the liquid yield with particle sizes ranging from . - . mm [ ]. the calorific value of the bio-oil is found to be slightly lesser than the diesel fuel. table . shows the properties of bio-oil obtained under optimum conditions reported by e. ganapathy sundaram et.al [ ]. bio-oil flash points found in open literatures are in the range of - c or above c, which depends on the volatiles organic content [ ]. table . experimental observations of bio-oil properties bio-oil [ ] bio-oil [ ] diesel fuel [ ] ,[ ] elemental carbon hydrogen nitrogen oxygen (wt %) . . . . - - - - (wt %) . % . % - - international journal of recent technology and engineering (ijrte) issn: - , volume- issue- , november retrieval number: c / ©beiesp doi: . /ijrte.c . published by: blue eyes intelligence engineering & sciences publication density(kg/m ) viscosity flash point hhv / gcv(mj/kg) at °c (cst) (°c) . . . at °c (cst) > (°c) . . at °c (cst) – °c - . iv. conclusion the calorific value of coconut shell ranges from - (mj/kg). the energy crisis can be compensated by using the abundantly available coconut wastes across villages in india. for pyrolysis process the most suitable resource is coconut shell, due to its less content of ash, higher proportion of volatile matter and surplus availability in rural villages all around the year. the bio-oil yield of the pyrolysis process depends up on the molecular structure of organic matter, the degree of metamorphism, the rate of heating, the removal of volatile substances, and the intensity and time of thermal action. acknowledgement nagaraja m , highly expresses his gratitude for support by dr.sundaresan .r former sr.professor of vit university for successful completion of the research work. abbreviations co is the % of carbon monoxide\\ co is the % of carbon dioxide ch is the % of methane h is the % of hydrogen hhv is the higher heating value lhv is the lower heating value (or net calorific value) references . j. ganan, a.al-kassirabdulla, a.b.miranda,j. turegano,s. correia, e.m. cuerda, energy production by means of gasification process of residuals sourced in extremadura, renewable energy. , , – . . e. ganapathy sundaram and e. natarajan, pyrolysis of coconut shell: an experimental investigation, the journal of engineering research , ( ), - . . alberto j. tsamba, weihong yang, wlodzimierz blasiak, pyrolysis characteristics and global kinetics of coconut and cashew nut shells, fuel processing technology. , , – . . mohammad uzzal hossain joardderet.al, pyrolysis of coconut shell for bio-oil, proceedings of the international conference on mechanical engineering. - december . . mustafa balat, mehmet balat, elif kırtay, havva balat, main routes for the thermo-conversion of biomass into fuels and chemicals. part : pyrolysis systems, energy conversion and management. , , – . . l. fagbemi, l. khezami, r. capart , pyrolysis products from different biomasses: application to the thermal cracking of tar, applied energy . , , – . . v. f. olontsev, i.a.borisova and e. a. sazonova, pyrolysis of coconut shells for the manufacture of carbon sorbents, solid fuel chemistry. ( ), – . . diesel data sheet, chemical and physical information. www.scielo.org , www.iocl.com/products/dieselspecifications.pdf authors profile sasikumar.c, ph.d from anna university, chennai. his research interest includes biodiesel extraction using pongamia & jatropha. he is an associate professor in department of mechanical in bannari amman institute of technology (bit), sathyamangalam. r. sundaresan had his ph.d from iit madras, chennai. he had executed funded project supported by ugc, dst and brns in vit university. he supervised ph.d & m.s., candidates. his research interest includes biomass, heat transfer in fluidized bed renewable energy. he is life member of iste, ishmt, sesi and fie. m. nagaraja through dst fellowship in vit continued ms which regulation pertains to ph.d and later he upgraded m.s credits to ph.d and graduated with ph.d during by ballsbridge (uk accredited). with years of experience, his interest includes educational administration. ms.sivahari shankar did his master degree at mohammed sathak engineering college and his bachelor degree in psna. his research interest is concerned to the renewable energy utilization and optimization. s.karthikeyan did his ph.d in iit madras. his research interests also includes in the area of energy development and testing of thin surface coatings. also he is working in the field of robotics. http://www.sciencedirect.com/science/article/pii/s http://www.sciencedirect.com/science/article/pii/s http://www.sciencedirect.com/science/article/pii/s http://www.sciencedirect.com/science/article/pii/s http://www.sciencedirect.com/science/journal/ http://www.scielo.org/ http://www.iocl.com/products/dieselspecifications.pdf [ ] agenda-setting with local and national issues philip palmgreen university of kentucky peter clarke university of michigan authors’ note: the research reported on here was supported by a grant from the university of michigan’s horace h. rackham school of graduate studies. three factors lead to the hypothesis that agenda-setting should be weaker at the local political level compared to the national level: ( ) the more directly observable nature of local political problems, ( ) the nature and strength of local interpersonal political communication networks, and ( ) the relatively heavier media coverage of national political issues. this hypothesis was supported with data from respondents assigned at random to either local or national issue conditions and from a content analysis of television and newspaper coverage in toledo, ohio, of local and national issues. contrary to the findings of certain previous studies, network tele- vision was found to exercise a stronger agenda-setting influence than newspapers at the national level. newspapers, on the other hand, were the dominant agenda-setter at the local level. the relative agenda-setting influences of television versus newspapers are consistent with other data from this study concerning the relative strengths of the various media as sources of issue information. an object of much recent research has been the identi- fication of variables which mediate the agenda-setting function of the mass media. as mccombs ( a: ) states in his recent review of the agenda-setting literature, &dquo;no one contends that agenda-setting is an influence process operating at all times and all places in all people.&dquo; in his review, mccombs identifies a number of &dquo;contingent conditions&dquo; which have been shown by research to affect agenda-setting. these include the individual’s need for orientation, frequency of interpersonal discussion, level of media exposure, and voting decision state (decided versus undecided). [ ] the effects of political system level as this list illustrates, most of the mediating variables which have been identified thus far are at the psychological or individual level. little attention, however, has been directed toward various systemic factors which might enhance, mitigate, or modify agenda-setting processes. of particular relevance here might be the political system level (local-state-national) involved. yet the great majority of agenda-setting studies have been concerned only with national issues, and then mostly within the limited context of political campaigns. tipton, haney, and baseheart’s ( ) investigation of the kentucky gubernatorial campaign and cohen’s ( ) examination of the attributes of a local environmental issue in indiana are among the few exceptions to this rule. while each of these studies furnishes evidence of agenda-setting processes below the national level, there are numerous differences between the various political system levels, particularly between the local and national political spheres, which might lead us to expect similar differences in the ways in which individuals develop political cognitions about these areas. for example, the type and scope of local and national political issues differ widely. many national political issues may be perceived by indi- viduals to have little direct impact on their personal affairs. interest in national affairs is often dictated by an abstract empathic consideration for the welfare of the nation as a whole. a local plan for the busing of students, however, may inspire vigorous personal concern and participation in the political process. on the other hand, the grand scale of many national political issues imbues them with a perceived significance which cannot be matched by tradi- tional local political fixtures such as street repair, even though the latter may possess immediate personal rami- fications. for many persons, the magnetic attraction of politics on the grand scale may triumph over more imme- diate concerns about the quality of local garbage collection and lead to higher levels of information seeking about national affairs. i [ ] , another important consideration is the relative &dquo;imme- diacy&dquo; of many issues at the local level. the ability of citi- zens to witness firsthand many local political problems and events often may obviate the need to rely on the mass media as &dquo;extensions of one’s senses.&dquo; certainly a person does not need the media to inform him that street repair is a major community problem, particularly if one of the streets in question is in front of one’s home. neighborhood interpersonal networks are often heavily laden with content arising from personal observation. since every citizen of the community is a potential initial source for such local political &dquo;news,&dquo; it is easy to understand why this might be the case. further impetus is given to the importance of inter- . personal channels vis-a-vis the mass media by the nature of organized group life in most communities. many membes of local voluntary associations are at the same time elected or administrative officials in local government, or are important members of the local informal power structure (as businessmen, school administrators, lawye.rs, and so on). as such, these individuals are directly involved with many local political issues and are able to transmit their own local issue agendas to fellow group members who may be less politically active. information about national political affairs is also transmitted in this fashion, but probably much less frequently. thus, both the ability personally to observe local prob- lems and the greater influence of interpersonal channels at the local level should lead to a reduction in the influence of the media issue agenda on personal agendas. media coverage levels. one difference between the local and national political levels of obvious relevance to agenda-setting is the level of mass media coverage accorded issues of local or national origin. there is no doubt about mass media &dquo;gatekeepers&dquo; fascination with more momentous national issues. national affairs tend to receive the lion’s share of coverage in most newspapers, with the possible exception of local weeklies. television, with its national network ties, tends to lean even more [ ] heavily toward national political concerns. this national focus is in part dictated by economic considerations, of course. it is more economical to make heavy use of network or syndicated material (such as wire copy) than to invest heavily in local news operations. the heavier flow of national political affairs information should have ramifications, of course, for media-related learning. in terms of sheer information availability and redundancy we would expect higher average levels of individual exposure to information about national political issues. this should result in higher levels of learning about national politics over a broader range of issues, problems, and personalities. strictly in terms of issue salience, the greater magnitude of the media &dquo;stimulus&dquo; at the national level should lead to better learning of the media issue agenda than at the less heavily covered local political level. thus, three factors lead to the hypothesis that the agenda-setting influence of the mass media should be weaker with regard to local political issues: ( ) the greater ability of individuals personally to observe local political problems, ( ) the nature and strength of local interpersonal political communication networks, and ( ) the relatively heavier media coverage of national political issues. newspapers versus television as agenda setters as mccombs ( a: ) has noted, &dquo;one of the espe- cially intriguing questions arising from agenda-setting research is the relative efficacy of television and news- papers in influencing personal agendas.&dquo; a number of studies (mccombs, shaw, and shaw, ; mccombs, b; tipton et al., ; mcclure and patterson, a; patterson and mcclure, ; mullins, ; agnir, ; and williams, ) have found the newspaper to be superior to television as an agenda setter. since once again the evidence here derives from the national political level (except for the tipton et al. study of state issues), we might ask whether a similar [ ] superiority of newspapers would be observed with regard to local political issues. an examination of the character- istics of the two media in the local political context indi- cates that it would. if anything, we might expect to find an even greater superiority of newspapers. by almost any yardstick, only newspapers have a sufficient &dquo;newshole&dquo; remaining to give local issues substantial play once national issues have been allotted their customary heavy emphasis. even supposedly &dquo;local&dquo; television news is often heavily infiltrated by national issues, especially in the late evening time slot. apparently reflecting this imbalance in the relative abilities of newspapers and television to cover the local scene, observers of local politics. usually assign political preeminence to newspapers. banfield and wilson ( : ), without mentioning television, state flatly: &dquo;the metropolitan daily newspaper is one of the very few actors on the civic scene (the mayor or city manager is usually the only other) in a position both to take a comprehensive view of the public interest and to exercise a powerful influence upon all of the other actors. it is therefore a political insti- . tution of great importance.&dquo; long ( : ), in his classic essay on the local community as an &dquo;ecology of games,&dquo; states that the local newspaper &dquo;has a great part in determining what most people will be talking about, what most people will think the facts are, and what most people will regard as the problems to be dealt with ... to a large extent, it sets the civic agenda.&dquo; local political leaders evidently share such perceptions of important newspaper involvement in community affairs. in a survey of city managers of u.s. cities with popula- tions greater than , , boynton and wright ( ) found that over half of the managers estimated newspapers to be highly influential in determining the issues and policies of municipal government in their communities. in no community did a manager perceive newspapers to be without influence. by contrast, most managers saw tele- vision and radio as having only moderate or limited influence. [ ] in the present study, therefore, it was expected that newspapers would manifest a stronger agenda-setting effect (in terms of media agenda-public agenda correla- tions) than would television with both local and national issues, but that the relative dominance of newspapers would be greater at the local level. problems in making local versus national comparisons although a comparison of agenda-setting processes across political system levels would certainly appear desir- able, such comparisons are not easily made. simply comparing studies which employ national issues with others focusing on local issues can be highly misleading, since any differences observed may be due to differences in samples of respondents, media systems, and operation- alization of variables. in particular, agenda-setting studies are likely to employ different content analysis procedures, issue classification systems, analytical schemes, and methods of measuring the public issue agenda (e.g., inter- personal versus intrapersonal). thus, the cohen ( ) study, the only previous study of agenda-setting which employed local issues, cannot be juxtaposed with the myriad national investigations to provide direct local versus national comparisons. the present study attempted to remedy these and similar comparison problems by randomly assigning respondents in the same city (toledo, ohio) to either local or national issue &dquo;conditions,&dquo; and by employing the same measure- ment and analytical procedures in both samples. methodology data were gathered in toledo over a three-day period in early december as part of a broad study of political communication and information holding. the selection of toledo was based on two major criteria. first, its status as a major metropolitan area (population , in ) assured it of a large number of local issues or problems in the political arena at any particular point in time. second, toledo [ ] has a well-developed mass media system for covering both local and national political issues. personal interviews were obtained via professional inter- viewers from a modified random sample (sex and age quotas were imposed) of residents of the city of toledo ( years of age and older). every other household within randomly selected block clusters was alternately assigned either the local or national version of the questionnaire. this resulted (after removal of certain unusable questionnaires) in local (n = ) and national (n = ) samples which were closely matched on a range of demographic and communica- tion variables such as age, sex, race, length of residence, voter .registration, and newspaper and television use. in addition, the demographic characteristics of both samples conformed closely to ’j.s. census figures. measuring the publicagenda. respondents were asked to name &dquo;any problems facing people in this country [or toledo, depending upon whether the respondent was as- signed to either the local or national condition] which you think the government in washington [toledo city govern- ment] should work to help solve.&dquo; the respondent was then asked to choose that problem which he considered to be &dquo;most important.&dquo; the interview proceeded to focus on this problem. measuring the media agenda. a content analysis of toledo newspaper and television coverage of nominated problems was carried out for the two weeks immediately prior to the gathering of interviews. a comprehensive listing first was made of all issues nominated by respondents at both political levels. after some collapsing into categories, this resulted in a total of issues nominated at the local level and at the national. certain issues were nominated at both the local and national levels (e.g., &dquo;energy crisis,&dquo; &dquo;crime,&dquo;), resulting in a total of separate issues nomi- nated. content analysis category descriptions were devised . for each of these issues. in most cases where an issue was nominated at both local and national levels (e.g., &dquo;crime,&dquo; &dquo;energy crisis&dquo;), both toledo and non-toledo (state, na- [ ] tional) media content was included in arriving at the media coverage level for that issue. for example, all stories about crime, whether they concerned crime in toledo or crime in other areas of the united states, were included in calcu- lating the total media coverage level for &dquo;crime.&dquo; this cover- age level was then assigned to respondents in both the local and national political focus samples. an exception to this policy was made in those cases where the respondent specifically focused on either a local or national aspect of an issue (e.g., &dquo;education,&dquo; where most local respondents were concerned specifically with improving the toledo school system). in such cases, only local toledo content was employed in the coverage index for local respondents, while both toledo and non-toledo content was used in the index for national respondents. newspaper coverage was indexed by enumerating the total number of &dquo;stories&dquo;’ relating to each issue category (some stories related to more than one issue) which ap- peared in the toledo blade for the period november - , . coverage indices for the three major television net- works for the same period were based on an analysis of sum- maries of the evening news contained in television news index and abstracts, published by the vanderbilt television news archives of vanderbilt university. since the evening news was broadcast during this period in the same time slot by all three networks, an average television coverage index was calculated. local television news coverage was based on an analysis of transcripts of the : p.m. and : p.m. newscasts of the three major toledo television stations. again, an average index was calculated. an index of total mass media coverage was arrived at by summing the indices for the blade, the national networks, and the local stations. results there are rather striking differences in the number and kinds of issues which people singled out for attention at the [ ] local and national levels of government. at the national level, only issues were mentioned, with the energy crisis ( mentions) and corruption in government ( mentions) dominating the agenda. the only other issues receiving significant attention were inflation ( mentions) and welfare-poverty ( mentions). this high level of consensus is somewhat less in evidence at the local level. there, different issues were nominated, headed by crime ( mentions), housing ( ) welfare- poverty ( ), the local educational system ( ), and urban renewal ( ). local aspects of the energy crisis also received some attention ( mentions). although several other issues received such dual mention at both the local and national levels (e.g., crime, unemployment, drugs), the agenda on the. whole are characterized by very dissimilar kinds of issues, reflecting, it would appear, a rather acute public awareness of the differing scope and functions of local and national government. table provides a medium-by-medium comparison of issue coverage levels. the greater &dquo;newshole&dquo; available to newspapers is apparent at the local and national levels. overall, issues most frequently nominated by national respondents received dramatically heavier mass media coverage than local issues. national issues received twice as much coverage on the average (xn = . stories) than did local issues (xl = . ). when each issue is weighted by the number of respondents nominating that issue, the average coverage level is . stories for national respondents and . for local respondents. of national respondents, % nominated issues which received attention in at least newspaper and television stories in the two weeks prior to interviewing. by comparison, of local respondents nominated issues receiving coverage levels of only stories or less. the energy crisis, perceived chiefly as a national level issue, received the greatest share of media coverage ( stories). continued fascination with the watergate scandal [ ] table coverage (number of stories) by medium of local and national issues * ., do p.m. and : p.m. coverages are summed in this index. see note . **coverage levels with stories concerned with &dquo;corruption in government&dquo; and the &dquo;energy crisis&dquo; (issues perceived chiefly as national issues) removed. ***coverage levels with stories concerned with &dquo;crime&dquo; (an issue perceived chiefly as a local issue) removed. accounted for the great majority of the stories related to &dquo;corruption in government.&dquo; apparently reflecting this over- whelming media emphasis, these two issues were nomi- nated as &dquo;most important&dquo; by of the national re- spondents. by contrast, these issues received only nominations at the local level. at the local level, only the ubiquitous issue ofcrime( stories, nominations) com- manded coverage or nomination levels approaching those of the dominant national issues (except for local aspects of the energy crisis). agenda-setting. these findings thus are consistent with the generally recognized tendency of the media to give greater play to national issues. it was hypothesized that this tendency, in conjunction with the directly observable char- acter of many local political problems and the nature of local interpersonal political networks, would result in a weaker media agenda-setting influence at the local issue level. this hypothesis received strong support in this study, as evi- denced by the respective local and national correlations be- tween total media coverage levels for each issue and the [ ] table correlations (pearson r) between issue coverage and salience of issues-by news medium and by local and national levels .p < . . proportion of respondents at each political level who nomi- nated each issue as &dquo;most important.&dquo; the correlation (pearson r) at the local level is a modest . (n = issues), while at the national level (n = issues) it is a relatively strong . (difference between r’s significant at . ). newspapers versus television. it was hypothesized that when agenda-setting is broken down by individual medium, the newspaper would prove to be a stronger agenda-setter than television, and that this superiority would be even stronger with regard to local issues. this hypothesis re- ceived only partial support, and, asthe data in table reveal, there is a need to specify which type of television coverage is under consideration, since large differences emerge in the relative influence of local television news and national net- work coverage. as expected, newspapers (the blade) exerted the strong- est influence on respondents’ local issue priorities, fol- lowed by local television news. as one would expect, national network television coverage had no significant impact on local public issue salience. at the national level, however, national network tele- vision is clearly superior to the blade in setting the public agenda. the strong correlation (. ) between network news coverage and the public hierarchy of issue salience [ ] is all the more impressive in view of the large number of issue categories ( ) on which the correlation is based (since inflation due to issue aggregation is minimized). in any case, the results clearly are not in line with those of previous studies indicating a superiority of newspapers over television in setting national issue agendas. this discrepancy is further underlined by the strong agenda- setting influence of local television news (r = . ). this latter influence may be traced to the liberal coverage of issues defined as &dquo;national&dquo; (by respondents) provided by the toledo stations in their &dquo;local&dquo; news telecasts. a major reason for the discrepancy between this and prior studies may be that previous studies have been conducted during national campaigns, while this investiga- tion took place in a noncampaign setting. mcclure and patterson’s ( b: - ) study of the presidential campaign indicated that &dquo;if coverage of events like the watergate incident and the peace talks is eliminated, [national] television news gave more coverage to campaign activity-rallies, polls, strategies-than to issues.&dquo; fully one-third of the campaign coverage was devoted to such stories. thus, in the supposedly issue-oriented atmosphere of a campaign, extensive television coverage of these issues paradoxically was lacking. during noncampaign periods, however, in the absence of the magnetic attraction of campaign hoopla, broadcast journalists appear to devote more attention to the substantive issues of the day. this seems to be particularly true of the time period spanned by the content analysis phase of this study. both the energy crisis and watergate, the two issues most frequently nominated by national respondents, received heavy amounts of network (and &dquo;local&dquo; tv) coverage during this period. it appears reasonable to hypothesize that during periods when television coverage of issues is relatively lacking (e.g., during campaigns), the agenda- setting influence of this news source will be correspond- ingly diminished. when the magnitude of the issue &dquo;stim- [ ] . table percentages of respondents naming each medium as carrying the most information about issues *local n = , national n = . fifty-one local and national respondents felt no mass medium offered useful information. ulus&dquo; is relatively strong, the agenda-setting impact of television will be proportionately greater. newspapers, on the other hand, with much greater &dquo;newshole&dquo; and thus much greater flexibility in their ability to cover both issues and non-issue related events simultaneously, should show greater stability in agenda-setting influence over time. the media as sources of issue information. the relative agenda-setting influence of television versus newspapers found in this study are consistent with other data con- cerning the relative strengths of the various media as sources of issue information at the local and national issue levels. table shows the percentages of respondents naming each of four media as carrying &dquo;the most infor- mation that is useful&dquo; concerning each respondent’s self-nominated &dquo;most important issue.&dquo; at the national level, . % of those naming such a medium said television (no distinction was made between network and local tv) carried the most useful information. newspapers were far behind, with only . %. at the local level, news- papers and television shared the leadership position, with both preferred by . % of the local respondents. it may be assumed that respondents here meant local [ ] table percentages* of respondents discriminating one or more messages from each medium *percentages do not total to % since respondents could cite more than one source for each recalled message. tv news coverage, which displayed local agenda-setting power close to that of newspapers. of perhaps a more valid nature are data (see table ) indicating the number of respondents who could actually recall having &dquo;seen, read, or heard&dquo; anything concerning their &dquo;most important&dquo; issues in the toledo media in the two weeks prior to the interview. these message discrimi- nation data show television (again, no distinction between network and local tv) once again as the primary source of information about national issues, with . of respon- dents able to recall at least one message from that me- dium. newspapers are second with . g . on the other hand, newspapers provided the most information about local issues- . °~ discriminated messages from that source compared to . °~ for television. it should be noted that message discrimination measures are indices of &dquo;effective&dquo; issue coverage by the various media, once audience members’ information selection processes have had an opportunity to operate. the pre- sence of issue information in media channels cannot induce agenda-setting effects unless audience members are exposed to that information. the concept of &dquo;effective coverage&dquo; is particularly important with regard to the relative impact of newspapers and television at the national [ ] level. on the basis of sheer coverage levels, we would expect newspapers to be the dominant agenda-setter at the national level (see table ). apparently, however, television is more &dquo;efficient&dquo; in disseminating its mes- sages, as the data in tables and indicate. this greater efficiency is translated into the relatively stronger agenda- setting effect of television for national issues. discussion the results of this study indicate, then, that the media play very different agenda-setting roles depending on whether the issues under study are of local or national political origin. first, the agenda-setting impact of the media as a whole vis- -vis other information sources is generally weaker at the local level. squaring the agenda- setting correlations found at each political level reveals that the media agenda (all media combined) accounted for a sizable ~ of the variance in the public agenda at the national level, while &dquo;explaining&dquo; only °~ of the variation in local issue salience. while the latter percentage still is indicative of considerable media influence at the local level, the impact of alternative sources of information (e.g., interpersonal channels, personal observation) is strongly indicated. second, the relative agenda-setting influence of news- papers and television appears to depend on the political level involved. newspapers, network television, and local television news programs have very different informational roles to play at each level. these differences are reflected in agenda-setting terms. the results here also strongly suggest the need to con- sider still another political context variable in making intermedia comparisions: campaign versus noncampaign periods. it seems highly plausible that the discrepancy between the findings of this study and earlier inquiries into the relative agenda-setting powers of newspapers and television is due to the noncampaign context of this investigation. comparative studies which employ the same [ ] methodology in exploring agenda-setting during campaign and noncampaign periods are needed. as mccombs ( a: ) has observed, &dquo;public issues can be arrayed along numerous dimensions: local versus national, the personally-close versus the distant, emotional vs. abstract, etc. it is not likely that the agenda-setting function of the mass media is concerned equally with all types of issues ceteris paribus. the salience of some types of issues on personal agenda are likely to show significant media influence while others show little or ’ no such influence. furthermore, interactions between types of issues and other agenda-setting variables are highly likely.&dquo; the wisdom of these observations is amply demonstrated by the findings of this study. certainly the agenda-setting function, which emerged initially in a form hauntingly reminiscent of the old &dquo;hypodermic needle&dquo; model of media effects, has been shown by recent research to be a highly complex phenomenon contingent on a variety of conditions. type of issue would seem to be one condition deserving special research attention. notes . for newspapers, a "story" was defined as any general news item, analysis piece, feature article, or editorial occupying three or more column inches (photo- graphs and editorial cartoons were excluded). for multiple-topic items, the item was coded in a particular category only where at least one column inch (total) of copy was devoted to the topic. for both newspapers and television, an item was coded in as many categories as applied. also, only content was coded which directly concerned events in the united states, except where the topic was inter- national in focus (e.g., "underfed children overseas"). items which for the most part concerned non-toledo affairs, but which specifically related the topic in question to toledo, were coded under both non-toledo and toledo content categories. . in the process of abstracting, the television news archive classifies the content of each news program into separate "stories." each of these stories is presented in the abstracts as a separate paragraph. these paragraphs were thus used as the story unit for content analysis purposes. . the local television news transcripts also preclassified different news stories by presenting each story in a separate paragraph. six o’clock and : p.m. coverages were summed to reflect the greater probability of audience ex- posure to content carried in both time slots. [ ] . an intercoder reliability check was carried out for the coding of the toledo blade. this check revealed . % agreement in coding a sample of items into the various content categories. a similar check on the coding of the television network news summaries and local television news transcripts was not considered necessary, since the newspaper content was judged to be the most difficult to code and thus most subject to coding error. . zero-order instead of partial correlation coefficients were employed because the high intermedium coverage correlations at both the local and national levels (r’s ranged from . to . ) would have caused severe multicollinearity problems. the estimates of the partials thus would have been highly unstable (see blalock, ; farrar and glauber, ). . mcclure and patterson ( b) state that television network news must meet five preconditions if it is to have "a unique and powerful impact." one of these conditions is that the event must take place outside the context of a political campaign. . for in-depth discussions of the message discrimination technique see clarke and kline ( ), palmgreen, kline, and clarke ( ), and miller ( ). references agnir, f. ( ) "testing new approaches to agenda-setting: a reflection and extension," in m. mccombs and g. stone (eds.) studies in agenda setting. new york: syracuse university newhouse communications research center. banfield, e. c. and j. q. wilson ( ) city politics. cambridge, ma: harvard university press. blalock, h. m. ( ) "correlated independent variables : the problem of multi- collinearity." social forces : - . boynton, r. p. and d. s. wright ( ) "the media, the masses, and urban management." journalism q. : - . clarke, p. and f. g. kline ( ) "media effects reconsidered: some new strategies for communication research." communication research : - . cohen, d. ( ) "a report on a non-election agenda-setting study." paper presented to the association for education in journalism, ottawa, canada. farrar, d. e. and r. r. glauber ( ) "multicollinearity in regression analysis : the problem revisited." rev. of economics and statistics : - . long, n. e. ( ) "the local community as an ecology of games." amer. j. of sociology : - . mccombs, m. ( a) "agenda-setting research: a bibliographic essay." pol. communication rev. : - . &mdash; ( b) "mass communication effects across time," in d. l. shaw and m. mccombs (eds.) the emergence of public issues. (in press) &mdash;, d. shaw, and e. shaw ( ) "the news and public reponse. three studies of the agenda-setting power of the press." paper presented to the association for education in journalism, carbondale, illinois. mcclure, r. d. and t. e. patterson ( a) "agenda-setting: comparison of newspaper and television network news." paper presented to the conference on the agenda-setting function of mass communications, syracuse university, new york. [ ] &mdash;( b) "television news and political advertising: the impact of exposure on voter beliefs." communication research : - . miller, p. v. ( ) "issues in conceptualization and measurement of message discrimination." university of michigan program for mass communication research. (unpublished) mullins, l. e. ( ) "agenda-setting on the campus: the mass media and learning of issue importance in the ’ election." paper presented to the association for education in journalism, fort collins, colorado. palmgreen, p., f. g. kline, and p. clarke ( ) "message discrimination and information holding about political affairs: a comparison of local and national issues." paper presented to the international communication association, new orleans. patterson, t. e. and r. d. mcclure ( ) the unseeing eye. new york: g. p. putnam. tipton, l. p., r. d. haney, and j. r. baseheart ( ) "media agenda-setting in city and state election campaigns." journalism q. : - . williams, w. ( ) "the agenda-setting function of newspapers and public radio: an analysis of the intrapersonal method." paper presented to the speech communication association, houston, texas. philip palmgreen is an assistant professor in the department of human communication at the university of kentucky. his research interests are in political communication, communication theory, and media effects. peter clarke is professor and chairman of journalism, university of michigan. his research interests include communication and political behavior, as well as use of mass media by the young, and he is co-series editor (with f. gerald kline) of sage annual reviews of communication research. an empirical analysis of rural and urban populations’ access to electricity: evidence from pakistan energy, sustainability and society rehman et al. energy, sustainability and society ( ) : https://doi.org/ . /s - - -y original article open access an empirical analysis of rural and urban populations’ access to electricity: evidence from pakistan abdul rehman *, zhang deyuan , abbas ali chandio and imran hussain abstract background: this study explores the electricity access to rural and urban populations and its impact on the economic growth in pakistan. methods: an autoregressive distributed lag (ardl) bounds testing approach was applied, and a co-integration test was used to investigate the dynamic causality relationships between the study variables. by using this testing approach, this study filled the literature gap regarding the access of rural and urban population to electricity in pakistan. results: the tests shed light on the long-run relationship among the variables, whereas the results revealed that the access of both rural and urban populations to electricity had a positive and significant effect on economic growth. conclusions: according to these findings, we can conclude that pakistan should pay further attention to increasing its electricity production from different sources, including not only hydroelectric, solar, wind, oil, gas, and biomass but also fewer and fewer nuclear sources, in order to fulfill the country’s demands on its way to a future of sustainable development. keywords: electricity, economic growth, rural population, ardl, urban population background a region’s energy supply is a key determinant of its eco- nomic development and social prosperity. with the rapid development of science and continuous innova- tions in technology, energy utilization is also constantly expanding. as a result, the energy demand has increased while resources have become strained from the burden [ ]. pakistan’s electricity sector is made up of two verti- cally integrated public sector utilities: the water and power development authority and the karachi electric supply company. approximately independent power producers have provided significant contributions to power generation in pakistan. in recent years, pakistan’s power generation has decreased by % due to its over-reliance on hydroelectric power. in , pakistan’s electricity power supply was below the demand of the population, which was % [ ]. * correspondence: abdlrehman@ahu.edu.cn research center of agricultural-rural-peasants, anhui university, hefei, china full list of author information is available at the end of the article © the author(s). open access this artic international license (http://creativecommons reproduction in any medium, provided you g the creative commons license, and indicate if pakistan’s electricity generation sector is a mixed in- dustry of hydropower, heat, and nuclear power plants. about % of its electricity is produced by hydroelectric systems, . % comes from thermal systems, and the remaining . % is generated from nuclear power. the country imported . % of its natural gas, . % of its oil, . % of its hydropower, and . % of its natural gas to meet its energy needs. contributions of coal and nu- clear energy to its energy supply are currently limited to . % and . %, respectively [ , ]. unless every country is now experiencing this same sporadic crisis that is combined with growing energy consumption and envir- onmental costs, all governments around the world are forced to further focus on monitoring and managing their energy markets [ ]. pakistan’s population has grown from . million in to . million in . the country’s growing population, industrialization, and increasing average household income have contributed to the growth of electricity demand [ – ]. it is worth noting that domes- tic sectors use electricity most heavily, at an average le is distributed under the terms of the creative commons attribution . .org/licenses/by/ . /), which permits unrestricted use, distribution, and ive appropriate credit to the original author(s) and the source, provide a link to changes were made. http://crossmark.crossref.org/dialog/?doi= . /s - - -y&domain=pdf mailto:abdlrehman@ahu.edu.cn http://creativecommons.org/licenses/by/ . / rehman et al. energy, sustainability and society ( ) : page of annual rate of . %. as a result, the general population suffers the most when a serious electricity shortage oc- curs in pakistan. electricity consumption in the com- mercial sector increased by an average of . % annually, and in , pakistan’s population increased at a rate of % annually [ ]. on the electricity supply side, compared to the demand rate of about % per annum, the power generation only increased at an average an- nual rate of %. as a result, the cumulative effect of the electricity supply-and-demand gap has adversely affected pakistan’s economy. in , the power shortage reached mw [ ]. the agricultural sectors of developing countries in the south asian region play an important role in their econ- omies [ , ]. in developing countries such as pakistan, the majority of the rural population is not connected to the electrical grid. in addition, power grids in rural areas, especially during the summer months, experience power shortages for up to h per day. off-grid generation via indigenous resources might help to reduce such power shortages and provide electricity to rural areas that lack access to the national grid [ , ]. these power short- ages have caused enormous damage to pakistan’s econ- omy and created binding and forceful restrictions to the country’s growth. they limit the growth of gross domes- tic product (gdp) and have a very serious negative im- pact on employment, international competitiveness, exports, and poverty reduction. for ordinary citizens, the heavy load reduction has caused serious damage to their daily lives. for the industrial, commercial, and agri- cultural sectors, the cost of electricity shortages is enor- mous, and pakistan’s overall economy has been greatly weakened. for example, more than half of its textile ex- ports and about % of its manufacturing jobs, including small businesses, have also been affected [ – ]. energy in the form of electricity production plays a vital role in the overall growth of a country and in other industries. a sustainable means of electricity production can im- prove a country’s economy, quality of life, and social well-being. at this stage, the role of policymakers is not only to assess and review current strategies to reduce the gap between electricity supply and demand, but also to develop future strategies to ensure affordable electri- city that is effectively distributed to contribute to a sus- tainable development in the country [ – ]. natural gas, oil, coal, biomass, hydropower, wind, and solar energy are basic foundations for local and indus- trial usage of energy. it is found that pakistan’s wind power potential is much higher than that of solar power generation, regardless of a high potential for solar power concentration. in addition, the best wind and solar power combination shows that % of wind power and % of solar power generation result in the lowest power shortage. the climatic conditions and geographic location of the country do provide a high solar energy potential, which means that solar energy resource assess- ments are needed for the planning of solar energy pro- jects [ – ]. solar energy might be an alternative means of producing electricity, but the country lacks modern solar technology. likewise, it is important to ini- tiate and direct the efficient usage of energy producing sources, their extraction, infrastructure, and develop- ment. the government of pakistan may launch microfi- nance schemes to support the production of electricity from solar and bioenergy sources, and top priority should now be given to an urgently needed adequate, re- liable, and affordable electricity supply. also, necessary policies should pursue an increase of indigenous electri- city production from gas and other reliable sources to meet the country’s growing energy needs. the major aim of this study was to explore the access of rural and urban populations to electricity and its in- fluence on the economic growth in pakistan. an aug- mented dickey-fuller unit root test was used to investigate the stationarity of the variables, whereas an autoregressive distributed lag (ardl) bounds testing ap- proach to co-integration was employed to check the as- sociation among the study variables using long-run and short-run relationships. aside from the background section, the rest of the art- icle is organized as follows: the section “the current electricity situation in pakistan” provides the current electricity situation in pakistan; the “materials and methods” section describes the data sources and empir- ical model specification. the “empirical estimation strategy” section specifies the unit root test for the sta- tionarity of the variables and the co-integration with the auto regressive distributed lag (ardl) model. the “results and discussion” section presents the results of the unit root test, the co-integration test, the long-run re- lations, the short-run relations, and the structural stability test. finally, the “conclusion and policy implication” section provides the policy recommendations in terms of electricity production from different alternatives as well as the short-term and long-term policies. the current electricity situation in pakistan pakistan’s power sector is facing its worst crisis to date. it supports an overloaded infrastructure and is under capacity, which makes it vulnerable to unprecedented load shedding, excessive loss of transmission and distri- bution, and a large amount of revolving debt. according to pakistan’s electric power company data, in april , the country generated more than mw of electricity, but the country’s demand stood at , mw, leaving a shortage of mw. some rural areas experienced load shedding and blackouts for up to h per day, while load shedding in the city areas increased fig. access to electricity (% of population) rehman et al. energy, sustainability and society ( ) : page of to h per day. in may , the shortage increased to mw, at an estimated demand of , mw, whereas the supply amounted to only mw [ , ]. under the current policy, the supply gap is expected to continue as it is estimated that starting from , elec- tricity shortages will increase to mw, hitting , mw in [ ]. pakistan’s electricity demand is partly driven by factors such as population growth, economic expansion, electri- city prices, people’s movement in cities, and the weather. however, the problems that are specific to pakistan and the crisis that has caused its electricity shortage are due to theft and overuse of electricity in domestic and industrial sectors, resulting in a huge loss of power lines, low institu- tional capacity, corruption, mismanagement, and political controversy in mega-power projects [ ]. policymakers should be fully aware of future electricity use projections so that they can take appropriate steps to close the gap. various studies have been conducted focusing on the needs of pakistan’s electricity sector [ , ], electricity sources, and their residential consumption [ , ]. electricity infrastructure planning and the growing de- mand in electricity and gdp are interrelated, especially in developing countries such as pakistan. pakistan has a one-way causal link between economic activity and electri- city use, which points to an increase in electricity demand and to a higher economic growth [ ]. hence, the demand for electricity has unexpectedly increased due to a steady % growth in gdp from to ; however, without proper infrastructure planning in the power sector, the country has faced severe power outages, resulting in a . % loss of gdp, . million industrial workers out of work, and export losses worth $ . billion in [ ]. the per capita electricity consumption in pakistan increased from to kwh, which amounts to about one fourth of the world average [ ]. the installed capacity of electricity increased to . million megawatts (mw) in and from . million megawatts (mw) during the corre- sponding period last year; however, generation declined from , gw/h in to , gw/h in . a slowdown in the share of hydropower in electricity gener- ation caused a decline of % during the corresponding period of . this mainly occurred due to less flow of water in rivers and difficult weather conditions [ ]. the barriers to rural electrification are economic, legal, fiscal, and institutional ones [ ]. having appropriate authorities is also a condition for innovation in electrical access as well as for public–private partnerships. in addition, they are crucial to raising the funds that are necessary to extend power access [ , ]. it is worth not- ing that an appropriate institutional and policy design is often obstructed by vested interests. therefore, successful countries often employ bottom-up approaches that in- volve local citizens in their electrification plans [ – ]. the future direction of energy policy is based on wide-ranging economic parameters as well as environ- mental and political factors that determine which tech- nologies should be deployed to meet future energy needs. pakistan’s electricity sector is facing its worst financial cri- sis ever in terms of its energy dynamics. its electricity sec- tor has tragically failed due to substandard maintenance of power plants, erroneous predictions that led to downsizing of employees, misuse of electricity subsidies, and mixed energy, resulting in a shortage of mw [ ]. accord- ing to the special parliamentary committee which han- dled the energy crisis of , an accumulated circulating debt worth $ . billion was calculated [ ]. in the short term, two key issues are being resolved on a fast track. one problem is the inefficient recovery system, and the other is transmission and distribution losses. the ministry of water and power has shown significant improvement of both issues. during , the recovery ratio amounted to . as compared to the past years while the distri- bution and transmission losses declined to . % during the aforementioned period [ ]. policymakers should therefore be fully aware of future electricity use so that ap- propriate measures can be taken to bridge this gap. in pakistan, various studies have been conducted on sectorial level electricity needs [ , , ]. electricity access among rural and urban populations and economic growth from to are illustrated in figs. , , , and . materials and methods data sources this study explores the access of electricity to the rural and urban population and its impact to the economic growth in pakistan over a period from to . time series data were collected from an economic sur- vey of pakistan and world development indicators (wdi). the variables used in this study are gross domes- tic product (annual %), electricity access to the rural fig. access of the urban population to electricity fig. economic growth of pakistan in % rehman et al. energy, sustainability and society ( ) : page of population (% of total), and electricity access to the urban population (% of total), respectively. empirical model specification in order to explore and examine the long-run and short-run analysis and the linkage between electricity ac- cess to the rural and urban population and its impact to economic growth in pakistan, this study employed a multivariate regression model specified as: gdpt ¼ β þ β eatrpt þ β eatupt þ εt ð Þ by using a natural logarithm to eq. , a log-linear model is as follows: lngdpt ¼ β þ β lneatrpt þ β lneatupt þ εt ð Þ whereas lngdpt indicates the natural logarithm of gross domestic product (gdp), lneatrpt indicates the natural logarithm of the access of the rural population to electricity, lneatupt represents the natural logarithm of the access of the urban population to electricity, t fig. access of the rural population to electricity denotes the time dimension, and εt denotes the error term. equation represents the log-linear form of the variables. the coefficients of the model β to β repre- sent the elasticity of the long-run. empirical estimation strategy unit root test for stationarity despite the fact that the auto regressive distributed lag (ardl) model requires no pre-testing for check- ing the unit root test for the stationarity of the vari- ables, augmented dickey-fuller (adf) [ ] unit root tests, including trend and intercept, were used to determine that none of the variables considered were integrated to order . as an ardl bounds testing approach is invalidated in cases where i( ) variables are used, an adf unit root test was per- formed using eq. . Δmt ¼ α° þ β°t þ β mt− þ xm i¼ α Δmt− þ μt: ð Þ where m indicates the variables being tested for the unit root, t represents a linear trend, Δ indicates the first dif- ference, t shows the time, μt is the error term, and m represents how to achieve white noise residuals. co-integration with the auto regressive distributed lag model to check the long-run and short-run relationship between the dependent and independent variables, this empirical study used an ardl bounds testing approach which was developed by pesaran and shin [ ] and which was further extended by pesaran et al. [ ] and narayan [ ]. the co-integration testing approach is applicable regardless of the order of integration with the concerned variables, i( ) and or i( ), except for the presence of i( ). the long-run and short-run relationship examined the ardl table ardl bounds test for co-integration results f-statistic significance level (%) lower bound upper bound decision . . . co-integrated . . . . rehman et al. energy, sustainability and society ( ) : page of representation of the unrestricted error correction model (uecm) of eq. ( ), as depicted in eq. ( ): Δlngdpt ¼ α þ xp i¼ α iΔlngdpt−i þ xq i¼ α iΔlneatrpt−i þ xq i¼ α iΔlneatupt−i þ β lngdpt− þ β lneatrpt− þβ lneatupt− þ εt ð Þ where Δ indicates the difference operator and β indicates the coefficients of long-run, while α captures the coeffi- cients of the short-run. the long-run co-movement among the variables of interest is ascertained on the basis of the estimated f-statistic. pesaran et al. consti- tuted two values available for the test of co-integration: ( ) lower bound critical values, where the variables are integrated to order zero [i.e., i( )], and ( ) upper bound critical values where the variables are integrated to order one [i.e., i( )]. the hypothesis of no presence of a long- run association is rejected when an estimated f-statistics exceeds the upper bound critical values. eventually, this empirical study allows the long-run elasticity and short- run adjustment parameters in eq. to be investigated. results and discussions results of unit root test a unit root test was performed solely with the aug- mented dickey-fuller (adf) test by considering the levels of the variables, first with an intercept and with both intercept and trend and subsequently the test was extended to include the first difference of the variables that were not stationary as could be seen in the table . the unit root test indicates that no variable was integrated with an order of i( ) and that the ardl model applied. results of the co-integration test a co-integration test was used when an f or w statistic was applied to the upper bound of the selected significant level. it is worth noting that the “f” test assumes that there is no co-integration null hypothesis between the variables. the various statistics are reported in table . the bounds tests shown in the table pointed to the existence of a co-integration relationship between table adf unit root test (trend and intercept) variables levels first difference conclusion lngdp − . ** − . *** i( ) lneatrp − . ** − . *** i( ) lneatup − . ** − . *** i( ) *, **, *** denote the rejection of the null hypothesis of unit root at the %, %, and % significant level, respectively economic growth and all independent variables at %, %, and %. results of the long-run relations the results of the long-run relations are presented in table . in the model that focused on the elasticity of the vari- ables, the results revealed that electricity access to the rural population has a coefficient of . , which is positive and significant with a p value of . . this means that a % increase in the access of electricity to the rural population with its explanatory power of . also points to increases in economic growth of . %. the coefficient of the access of the urban population to electricity also has a positive impact on economic growth with a coefficient of . and a p value of . , respectively. various aspects of pakistan’s power sector have been considered, such as the gap between supply and demand, energy supply reduction, energy se- curity, and increased energy costs. furthermore, the en- ergy status and potential of renewable energy have been discussed as a sustainable alternative. the model also discusses the role of different sectors of renewable energy technologies in promotion and development [ , ]. a total of sustainability indicators were evaluated, including the life cycle of the seven power sources currently in use. the rankings of these sources also weigh the sustainability aspects and their respective indicators. hydropower is considered to be the most sustainable option with a minimal environ- mental and economic impact. because it causes the most significant economic and social impact, oil is considered the least sustainable option for the coun- try [ , ]. results of short-run relations the existence of a cointegration relationship among the variables requires an error correction model (ecm) to table results of long-run relationship dependent variable is lngdp regressors coefficients std. error t-ratio p value lneatrp . . . . lneatup . . . . c − . . − . . table diagnostic and stability tests test statistics (lm version) statistics (prob-values) breusch-godfrey serial correlation lm test . ( . ) j-b normality test . ( . ) heteroskedasticity test: arch . ( . ) p values are given in the parenthesis rehman et al. energy, sustainability and society ( ) : page of capture the short-run dynamics of the system and its co- efficient, which measures the speed of adjustment to ob- tain equilibrium in the event of shocks to the system. table depicts the results of the short-run dynamic growth equation. the short-run dynamics of the model were esti- mated using an r-squared value of approximately %, meaning that approximately % of the vari- ation in agricultural growth was explained by the in- dependent variables in the model. the f-statistics confirmed the joint significance of all of the inde- pendent variables at the % significance level. the dw statistics was . , which was not equal to the standard dw value for the proof of absence of any autocorrelation; however, it was great enough to de- bunk the presence of any autocorrelation in the model. the short-run relationship indicated that the coefficient of electricity access to the rural popula- tion had a significant effect on agricultural growth. likewise, the coefficients of access of electricity to the urban population had a significant effect on agri- cultural growth. the establishment of new lines and substations alone will not allow us to achieve the goal of overcoming energy shortages. as a result, a major shift in the power infrastructure will take time to meet the growing power demands. converting the current power management system into an intelligent autonomous system is meant to achieve an increase in the amount of renewable energy generated. the main reason for the increase in the supply and de- mand gap is an increase in electricity demand, on the one side, and energy resources and financial con- straints, on the other. therefore, the government has implemented various initiatives, including a partial reorganization of the power sector in accordance with the guidance of international finance institu- tions [ , ]. the results of the diagnostic and stability tests are pre- sented in table . table results of short-run error correction representation dependent variable is lngdp regressors coefficients std. error t-ratio p value Δlngdp(− ) . . . . Δlneatrp . . . . Δlneatup . . . . c − . . − . . ecm(− ) − . . − . . r-squared . durbin-watson stat . adjusted r-squared . f-statistic . prob(f-statistic) . table depicts the results of the diagnostic and stabil- ity tests, including the breusch-godfrey serial correl- ation lm test, the j-b normality test, and the heteroskedasticity test with p values of . , . , and . , respectively. the normality test is also pre- sented in fig. . the structural stability test in the stability tests, a cusum and a cusum square point were introduced to increase the stability of the long-run and short-run parameters. the graphs of both the cusum test and cusum square test are mentioned in figs. and which also specifies that all values lie within the critical boundaries at a sig- nificance level of %. this allows us to confirm the long-run and short-run parameters’ stability over the period of – . conclusions and policy implications pakistan’s electricity sector continues to face challenges in addition to its current energy crisis due to inconsist- ent energy production. this study investigated the access of both rural and urban populations to electricity as well as the impact of this access on pakistan’s economic growth. the ardl bounds testing approach and a co-integration test were used to examine the dynamic causality relationship between the dependent and inde- pendent variables. the long-run relationship between the variables revealed that the access of rural and urban populations to electricity had a positive relationship with economic growth. our study results suggest that the fig. normality test fig. cusum test rehman et al. energy, sustainability and society ( ) : page of government of pakistan has enhanced policies regarding electricity production from different sources including production from natural gas, the solar system, hydro- electric sources, nuclear sources, and wind power gener- ators to fulfill the national demand. pakistan can produce cheap electricity from natural gas which is one of the most dominant sources of energy, as is oil. to meet the increasing electricity demand of both rural and urban populations, the government should enhance their energy policies and increase financial support to boost electricity production. pakistan has rich natural gas production and should explore this advantage. natural gas is a viable and low-cost alter- native for producing electricity. recently, pakistan is facing a water crisis, so that electricity production from hydropower cannot fulfill the demands. like- wise, the government should implement short-term and long-term energy policies to face pakistan’s en- ergy crisis. the government needs to concentrate on a better utilization of resources and pay attention to the discourse regarding debt circulation and issuance immediately, in order to restructure the revenue fig. cusum of squares test collection system and enhance rational energy pro- duction payments to the companies. this would cre- ate an easy way for power generation companies to attain funds and produce cheap electricity. the gov- ernment should also build new dams and transfer thermal energy sources to other reliable sources with the aim to produce more electricity. as for a long-term energy production policy, the government should invest in alternative energy sources such as wind-powered generation. this will improve the country’s electricity situation and enable the produc- tion of cheap electricity. moreover, the authors rec- ommend that the production of electricity from cheap and alternative sources receive more attention to im- prove the infrastructure, economic growth, and sus- tainable development of pakistan. acknowledgements the authors are grateful to the research centre of agricultural-rural- peasants, anhui university hefei, china for its financial and moral support. moreover, the authors are also indebted to the reviewers for their positive suggestions that helped to improve the content of this study. funding the paper was supported by the research centre of agricultural-rural- peasants, anhui university hefei, china. availability of data and materials all data and material is available in this paper, so there is no other data to present. authors’ contributions ar conceived the study, collected the data, and estimated the econometric model. zd and aac drafted the manuscript. ih read and made suggestions to the manuscript. all authors read and approved the final manuscript. ethics approval and consent to participate it is declared that this paper does not involve any human participants, human data or human tissue. consent for publication this paper does not include any individual person’s data in any form (including any individual details, images or videos). competing interests the authors declare that there is no competing interest. publisher’s note springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. author details research center of 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https://doi.org/ . /j.rser. . . https://doi.org/ . /j.rser. . . https://doi.org/ . /j.rser. . . 	abstract 	background 	methods 	results 	conclusions 	background 	the current electricity situation in pakistan 	materials and methods 	data sources 	empirical model specification 	empirical estimation strategy 	unit root test for stationarity 	co-integration with the auto regressive distributed lag model 	results and discussions 	results of unit root test 	results of the co-integration test 	results of the long-run relations 	results of short-run relations 	the structural stability test 	conclusions and policy implications 	acknowledgements 	funding 	availability of data and materials 	authors’ contributions 	ethics approval and consent to participate 	consent for publication 	competing interests 	publisher’s note 	author details 	references analysing optimum building form in relation to lower cooling load procedia - social and behavioral sciences ( ) – available online at www.sciencedirect.com - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of amer (association of malaysian environment-behaviour researchers) and ce-bs (centre for environment- behaviour studies, faculty of architecture, planning & surveying, universiti teknologi mara, malaysia. doi: . /j.sbspro. . . sciencedirect asli qol , annual serial landmark international conferences on quality of life asean-turkey asli qol aicqol jakarta, indonesia. amer international conference on quality of life the akmani hotel, jakarta, indonesia, - april “quality of life in the built & natural environment " analysing optimum building form in relation to lower cooling load wan sharizatul suraya w.m.rashdi, mohamed rashid embi* department of architecture, faculty of built environment, universiti teknologi malaysia, skudai, johor baru, malaysia abstract energy consumption would be an enormous matter as the number of people is increasing worldwide and resources are limited. the focus of the designer would be designing the building form to ensure less energy consumption. this research investigates the relationship between optimum building form in decreasing the cooling load. the study is conducted using computer simulation analysis program autodesk ecotect. the experimentation shows the relationship between building elements and cooling load. the outcome of the research reveals that compactness and lower ratios of surface to volume do give significant impact. based on the result is assumed that manipulation and selection of building form will help passively in reducing cooling load. © the authors. published by elsevier ltd. peer-review under responsibility of amer (association of malaysian environment-behaviour researchers) and ce-bs (centre for environment-behaviour studies, faculty of architecture, planning & surveying, universiti teknologi mara, malaysia. keywords: building form; energy efficiency; cooling load . introduction high energy consumption correspondingly starts from inefficient used for energy. in future, usage of energy would be a vital matter, as number people are increasing worldwide, and resources are limited. with the standard of * corresponding author. tel.: + - - ; faks + - - - . e-mail address: wssuraya@gmail.com © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of amer (association of malaysian environment-behaviour researchers) and ce-bs (centre for environment- behaviour studies, faculty of architecture, planning & surveying, universiti teknologi mara, malaysia. http://crossmark.crossref.org/dialog/?doi= . /j.sbspro. . . &domain=pdf wan sharizatul suraya w.m. rashdi and mohamed rashid embi / procedia - social and behavioral sciences ( ) – living enhanced, people incline to expect a better comfort level, which eventually the usage of the air conditioning system is a must. if the building is designed in such a way that it will enhances energy efficiency and comfort (zhang & lei, ), in a simple term the building can cool itself. there would be no need for installing air conditioning system that is large and expensive. small and fewer air conditionings mean significantly less energy consumption and more savings on electricity bills. in malaysia, most of all commercial offices engaged cooling systems takes up average % of the total energy consumption yearly (ahmad & abdul-ghani, ; suziyana et al., ). markus & morris ( ) stated that the designer of the buildings can have significant control over the building as merely by changing material and form of construction. material changing can affect the u-value or insulation value while the building construction method would influence air changes and ventilation loss. the designer has full impact on the parameters considerations. there are numerous ways how the actual dimension of height length and span varies which resulting in the diverse total surface area of a volume. two different building may have different surface areas and envelope heat loss, but both buildings may have the same size and materials. this paper aims at exploring optimize building form and its component, that illustrates less heat gain and eventually lower cooling load. shape, geometry and form of a building is influenced by the solar energy it receives as well giving impact to its energy consumption (markus & morris, ). the shape of the building has a significant effect on both construction costs, and energy costs of buildings (mingfang, ; ourghi et al., ; pacheco et al., ). however, deviation of energy values of the different shape are comparatively small, and window wall ratio shows a significant value compared to form as the heat gain enters mostly from an opening (ferdous, ). still, there is a high correlation between the shape of a building and its energy consumption (ourghi et al., ). the compactness of a form can reduce energy consumption (granit & möller, ). while alanzi et al., ( ) use compactness as an indicator in assessing the impact of shape on energy performance. building form and building envelope are the most important parameters affecting indoor climate (hemsath & alagheband bandhosseini, ; oral & yilmaz, ). there is a less research on building performance of the form based on cooling load capacity. most building research based on cooling would relate more towards improving air conditioning system capacity. while in other research context, building forms are explored more towards thermal comfort and solar radiation. based on these reviews, most studies on building form directly related to building aspect ratios such as surface to volume ratios, width to length, window to wall ratios and compactness. exploration of various variables can be perceived when building form is being experimented. the development of building form throughout the architecture design process would undoubtedly provide a better impact of energy efficiency. the building shape development to achieve better energy performance is essential. effect of heat gain externally and internally towards a building form is crucial. the building shape manipulation and changes will deter the heat calculated for cooling load. therefore, it is significance to explore the optimum building form that specifically lowered the cooling load and improve energy efficiency. . . building form and energy building form, spatial layout and arrangement configurations that are planned towards energy efficiency and based on climatic data is considered as a passive response. improvisation of energy used is not only on building orientation but influenced by the form of the building and ratio of the volume to a surface (yeang, ). size and orientation of the exterior envelope are the ones that exposed directly in an outdoor environment. these elements are determined specifically by the form that in turn affects the thermal performance of a building. even cost and esthetic are influenced by the building form. undeniably, selection of an optimum form, orientation, and envelope configuration can reduced energy consumption by % (mohammed hussein abed, ; wang et al., ). building form in architecture is an external appearance that can be identified, a reference to the internal structure and internal outline. the form usually includes d mass or volume and a defined shape that gives its outlook (ching, ). wan sharizatul suraya w.m. rashdi and mohamed rashid embi / procedia - social and behavioral sciences ( ) – . . cooling load the main purpose of the mechanical and electrical systems in buildings is to provide the space occupants to live and works comfortably and safe. through decades, building energy evolves to ensure better energy conservation compared to previous structures. the trends resulted from the energy crisis. the energy crisis significantly has altered how the designers designed a building. due to the energy crisis, numerous studies shows that air conditioning impose near % towards energy consumption in a building. thus in identifying a better system of the air conditioning system is to lower its heat gain by understanding its cooling load. to determine how the air conditioning system and building design relates, the cooling capacity is defined as the quantity of heat energy that needs to be eliminated from space to preserve the temperature by cooling apparatus or air conditioning system. the cooling load calculation will directly influence the building cost along with the operating indoor air quality, occupant comfort, energy efficiency, and building durability. there is a lot of design strategies have been attempted to encourage energy efficiency and reduce the energy consumption. by creating and designing building shape using the optimum form, it is one strategy for supporting the best design practice towards energy efficiency. architect as the designer are the one who participate in building design, starting from the initial ideas up to construction. architects have full control over building orientation, shape compactness of building, wall and insulation material selection, area orientation, colors of wall and roof material. the building system such as air conditioning system, water supply, lighting system, services can be controlled effectively to achieve comfort level of human inside the building when work in a collaborative team. positive collaboration would enhance building energy efficiency of the building. the interaction will give effect to the usage of daylight plus artificial lighting, zone switching with open areas lighting, and task lighting within the interior colours (nield, ; van moeseke, bruyère, & de herde, ). . . building forms and climate malaysia situated near to the equator and having hot and humid along the year with mean relative humidity more than percent and varies throughout the year. solar radiation is active with partly reflected and scattered by cloud in addition to high water vapor. solar radiation is a substantial concern in any building that strives for energy efficiency. as it helps in building massing and orient the building form on the site. the experimentation with building shape is closely related to climate, and different environment would yield the different result of its cooling load. basic understanding of hot-humid climate and based on other research shows that the long axis of a building form should face north as less heat gain can penetrate through the openings of the long axis. as the highest received, solar insolation level is on the east wall (ling, ahmad, & ossen, ) . methodology the computer simulation study is used in investigating the optimum building form in decreasing the cooling load. in the search for the optimum building shape that is having solar reduction that will lead to the lower indoor heated environment and the decrease of cooling capacity towards energy analysis. the first stage experimented with basic building form are rectangular, square, courtyard, l, t, u, ellipse, and circle shape (fig. (b)). second stages explored the extended building forms (fig (c)). shapes and forms are pure geometry that is commonly found in architecture and industry. the primary and extended building forms created and simulated as a prototype of a five stories institutional building equipped with full air conditioning system. based on the fundamental knowledge, these basic shapes are the basic form that will be used and analysed in the software simulation in order to see the dissimilarities or changes of cooling load in preliminary stage. while the second stage is experimenting with extended building forms. the extended forms are generated from the first phase experimentation and research reviews. the first stage and the second phase studies are conducted in primary and extended building form, which are based on google earth observation of major institution building of local context of five stories building. the main building shape is identified based on the literature study and existing building. wan sharizatul suraya w.m. rashdi and mohamed rashid embi / procedia - social and behavioral sciences ( ) – . . parametric analysis various design options with the reference to a climate may produce different energy consumption for each design options. most data and its comparative analysis have been done using computer software. the energy performance can be investigated during the conceptual design stage with the help of computer software. making several runs on the same building while varying only a single design parameter is known as a parametric study. effect of design variables on the building form has been investigated varying one variable at a time for a design day. the study scope is to explore the building shape potential in decreasing the cooling load that significantly creates a lower indoor heated environment. the primary building forms is being created in autodesk revit, simulated and analyze its energy analysis in the autodesk ecotect . the detail experimentation process of the manipulated building form is shown on fig (a). the experimentation of building forms will be varies according to it variables. the building forms are manipulated, and the variables such as volume, height, floor areas are set constant. the manipulations of basic forms (fig. (b)) and extended forms (fig. (c)) can be viewed from its transformation sizes of its length, width and orientation. once the simulation of the forms completed, it will produce the surface area, volume and surface ratio of the form that were tested. the compactness of the forms can be calculated using the volume to surface ratio. as the dimension and the properties of the building being shown and calculated, so does energy data. energy data presented are the cooling load, heat gain, and its temperature. most of the building elements such as door, column, structure, space floor size and volume, envelope design, type of material is set constant. then, the form will be simulated into various types of shapes and dimension. to complete the objectives, the study will analyze all alternative shapes and design ideas within the variables in autodesk ecotect analysis. it assumes various forms will give different cooling load calculation based on the building shape transformation and local climate. different forms will be heated differently based on the different angle of heat penetration and gain towards the building. based on american society of heating. refrigerating and air-conditioning engineers, to calculate a space cooling load, data regarding the building design and weather are required. primarily, ashrae has outlined six points that will influence and used in the cooling load calculation, there are: the building characteristic. configurations of building outdoor design conditions. indoor design conditions. operating schedules. date and time. hence, this data can be added to the software and being calculated using cibse method. cibse admittance method is based on a -hour cycle of a steady-state process. the software uses the cibse admittance method to calculate the amount of heating and cooling loads for a number of zones within a model. the benefit of the admittance method is fast and can interact dynamically with the design model. any changes to the material and design, the analysis result can be calculated quickly. to analyze, the selection of time and month in a year need to be identified to gather data on peak load time. individual exposure based on the month and solar condition around a year would be calculated, and usually the warmest temperature must be identified. as the weather data is the critical parameters in identifying the cooling load, the cooling load calculation will be based on selected location. the simulated building form is using kuala lumpur (subang jaya based) design weather data linked with the autodesk ecotect software. once, all data in all steps collected, the space cooling load at different design conditions will be calculated. however, only cooling load and heat gain calculation related to building form, shape, and design will be taken. the form typology and its components will correspond to its local climate and site context. from there, the result of cooling load data can be compared and analyzed. . . primary building form layout the study investigates the manipulation of the basic shape and form of medium five stories building in hot, humid climate and its impact towards the cooling load. the building is considered as unoccupied with internal loads wan sharizatul suraya w.m. rashdi and mohamed rashid embi / procedia - social and behavioral sciences ( ) – and infiltration. the important observation is how the cooling capacity differs from the architectural parameter being altered and manipulated, especially the transformation of forms. the study focus on the building forms which using entirely air-conditioning system, under the influence of hot and humid climate. the shape of the building to be analyzed would be based basic building forms and extended manipulated forms as shown in figure (b), (c). fig. . (a) experimentation process; (b) stage experimentation of basic forms (c) stage experimentation of extended forms the building forms floor area, volume, and height are being constant to ensure the calculation of its cooling load. while pertaining the building configurations, all forms will have the same information entered in the software shown in table . such data are operation schedules, regulations, space usage, desirable temperature, occupancy and other operational parameters. wan sharizatul suraya w.m. rashdi and mohamed rashid embi / procedia - social and behavioral sciences ( ) – table . building form design properties properties dimension five stories building height of each floor m² volume m³ area of each floor ± m² overall floor area m² . results and discussion selected results of the parametric analysis are discussed. . . compactness and surface to volume ratio fig. illustrates the impact of different primary building forms on the cooling load. the result of fig. indicates the cooling capacity or the rate of energy needed to remove the heat increased consequently within its loose shape. while the most compacted shape such as a circle (ling, ) and square shows lower cooling load. compactness of a shape is also identified as shape factor and defined as the surface area to volume ratio (herde, ). fig. graphs show the cooling load result are consistent with the surface to volume ratio relative to various basic forms. the lower its surface to volume ratio, the more compact the form become, the lower its cooling load. on which, the less amount of heat needed to be removed. the loose shape such as courtyard is shown to have higher cooling load when compared with the other fundamental forms. due to the most surface are prone to heat penetration from all sides. it is assumed as the more surface disposed of the sun radiation, the higher its cooling load. while a study by muhaisen & gadi, ( ) in the temperate climate indicate courtyard form that is deeper and shallower and extended longer are better in reducing cooling load. introducing shading devices in courtyard form also help improve reducing cooling load. this strategy would be one way of designing to ensure lower cooling load. wan sharizatul suraya w.m. rashdi and mohamed rashid embi / procedia - social and behavioral sciences ( ) – fig. . (a) basic forms cooling load (btu/hr) (b) basic forms surface to volume ratios . . orientation orientation plays an important part as it relates to the climate. the direction of long axis wall facing the east shows higher cooling load. the result is aligned with the fundamental knowledge of orientating the long axis facing north as the best orientation of a building form. based on the fundamental shape analysis the most fluctuated cooling load on orientation are the rectangular form as its width and length differ vastly compared to the other basic forms shape. a study on façade design, shows that orienting the larger façade away from the heated solar radiation will give much more lower heat gain (tzempelikos, athienitis, & karava, ). the other primary forms width and length shows not much significant difference based on the orientation. however, looking at the second stage analysis that explores on extended building shapes in fig. . there is more fluctuated cooling load data of manipulated extended building forms compared to different orientation. the data has been calculated, and the percentage difference between building forms in hot-humid orientations shows only % up to % difference. . . extended building forms based on the primary building shapes in stage , the next phase explores the manipulation of building forms, the manipulation can be seen from the figure (c). the rectangular forms are being split into smaller rectangular forms, then orientated and cut through like a see-saw form, combined with the longer axis and narrow width. the variations of basic form is classified as i , i a, i , i , i , i , i , i , i , i , l , l , u , u , and courty is representing courtyard form. the manipulation of building shape typology is based on sky overview of institution building typology and also based on building forms fundamental by francis d.k ching. extended building shapes in figure (b) shows more complicated result as the form is being transformed by various manipulation. the shapes, i , i , i , i , i .i , i , and i has been manipulated to identify how the building forms react in hot - humid climate in reducing the cooling load. indeed, the manipulation of i forms that represent the manipulation of rectangular primary form shows a difference result between orientations. that conclude small changes of the cooling load based on the orientation. the forms manipulation of the five stories building is designed without having windows, to see the effect on surface heat gains only. the introduction of window and opening towards the building form shows a nearly % percentage increase in cooling load. wan sharizatul suraya w.m. rashdi and mohamed rashid embi / procedia - social and behavioral sciences ( ) – fig. (a) extended forms cooling load (btu/hr) (b) extended forms surface to volume ratios l , l , and u forms show a decrease in cooling capacity compared to i manipulated forms. the analysis indicates that compactness of l , l and u plays important elements in decreasing the cooling load. while i , i , and i building shapes in graphs show a higher cooling load. due to the manipulation of solid and void in between the form as can be seen from figure (c). the larger cooling load is due to more surface expose to the sun heat gains. indeed, this experimentation result indicates a similar result within the previous study and shows that better forms can decrease cooling load passively. the result would initiate a better building forms design for air conditioning building. the result also indicates having longer axis orientating towards the east would have the higher cooling load. then, having a narrow axis and a small difference between its width and length also indicate lesser cooling load of the building forms. further studies will be based on a base case model. . conclusion the study revealed the optimized building form and geometric generated based on lower cooling load and better energy performance. a particular type of building shape and its components can lower down cooling load. still when considering the optimum way the shape is still based on its manipulation, so the result will be highlighted on how manipulation can be done to introduce better building form design. analyzing building form in relat ive to the cooling load gives imperative result significantly. building form with a loose form may have higher cooling load compare to the compact form. manipulation of building forms significantly affect the cooling load of the building. the more surface of a form prone to sun radiation, the higher its cooling capacity in line with the higher surface to volume ratios. wan sharizatul suraya w.m. rashdi and mohamed rashid embi / procedia - social and behavioral sciences ( ) – lower surface to volume ratio, the more compact the form, the lower the cooling load. a different orientation has the moderate effect on cooling, still orientating the long axis facing north would be the best alternative. considering optimize building form would be a guideline for the designer to start designing a building that is having the lower cooling load. the form would have a passive impact towards lowering electricity cost. the designer would opt certain techniques based on the guideline in ensuring the building significantly has reduced cooling load. eventually, when the engineer calculated the actual cooling load for the building the building would passively have energy efficiency. acknowledgements the authors wish to acknowledge the support by universiti teknologi malaysia and ministry of higher education, malaysia for this research. references ahmad, n. a., & abdul-ghani, a. a. ( ). towards sustainable development in malaysia: in the perspective of energy security for buildings. procedia engineering, , – . alanzi, a., seo, d., & krarti, m. ( ). impact of building shape on thermal performance of office buildings in kuwait. energy conversion and management, ( ), – . ching, f. d. . ( ). architecture : form, space and order. (third.). john wiley and sons, inc. ferdous, t. ( ). determining the effect of building geometry on energy use patterns of office developments. (unpublished thesis). granit, m., & möller, i. ( ). building shape and energy demands. batiment international, building research and practice, – . hemsath, t. l., & alagheband bandhosseini, k. ( ). sensitivity analysis evaluating basic building geometry’s effect on energy use. renewable energy, , – . herde, a. de. ( ). design of low energy office buildings. energy and buildings, . ling, c. s. ( ). minimizing solar insolation in high-rise buildings through self-shaded form. (unpublished thesis). ling, c. s., ahmad, m. h., & ossen, d. r. ( ). the effect of geometric shape and building orientation on minimising solar insolation on high-rise buildings in hot humid climate. journal of construction in developing countries, ( ), – . mingfang, t. ( ). solar control for buildings. building and environment, ( ), – . mohammed hussein abed, h. ( ). effect of building form on the thermal performance of residential complexes in the mediterranean climate of the gaza strip.(unpublished thesis). muhaisen, a. s., & gadi, m. b. ( ). effect of courtyard proportions on solar heat gain and energy requirement in the temperate climate of rome. building and environment, ( ), – . nield, l. ( ). energy as a major architectural design issue. in h. j. cowan (ed.), energy conservation in the design of multi-storey buildings ( th ed., pp. – ). pergamon press. oral, g. k., & yilmaz, z. ( ). building form for cold climatic zones related to building envelope from heating energy conservation point of view. energy and buildings, ( ), – . ourghi, r., al-anzi, a., & krarti, m. ( ). a simplified analysis method to predict the impact of shape on annual energy use for office buildings. energy conversion and management, ( ), – . pacheco, r., ordóñez, j., & martínez, g. ( ). energy efficient design of building: a review. renewable and sustainable energy reviews, ( ), – . suziyana, m. d., nina, s. n., yusof, t. m., & basirul, a. a. s. ( ). analysis of heat gain in computer laboratory and excellent centre by using cltd/clf/scl method. procedia engineering, , – . tzempelikos, a., athienitis, a. k., & karava, p. ( ). simulation of façade and envelope design options for a new institutional building. solar energy, ( ), – . van moeseke, g., bruyère, i., & de herde, a. ( ). impact of control rules on the efficiency of shading devices and free cooling for office buildings. building and environment, ( ), – . wang, w., rivard, h., & zmeureanu, r. ( ). floor shape optimization for green building design. advanced engineering informatics, ( ), – . yeang, k. ( ). ecodesign : a manual for ecological design. john wiley & sons. zhang, h., & lei, s. l. ( ). assessing the renovation of existing residential buildings regarding environmental efficiency. asian journal of environment-behaviour studies, ( ), – . . books mh remarkable qualities: sailor, cellist, and so on, and includes “communist”, without explana- tion. this is a reprehensible distortion. monod joined the french communist party during the war for just one reason, he told me: it was the only way he could have any influence on the strategy and tactics of the armed resistance, in which he then rose to chief of operations for all of france. after the war he quietly dropped out, until in he publicly denounced the fraudulent claims of stalin’s geneticist and sci- ence chief, trofim lysenko — and with terrific effect. ■ horace freeland judson is at west university parkway, baltimore, maryland , usa. coping with uncertainty from cosmos to chaos: the science of unpredictability by peter coles oxford university press: . pp. £ , $ . gianpietro malescio if the process through which civilization evolved were condensed into a few words, these could be: posing questions, finding answers. as those with children know well, wondering about the world is intrinsic to human nature. this attitude is generally lost as we grow up (life is a tough business), but a good scien- tist retains it as an adult. in principle, find- ing answers is the ultimate goal of a scientist. however, scientific answers have a peculiar character: they do not represent absolute truth acquired once and for all, but only temporary beliefs subject to continuous, critical revision. scientific knowledge is anti-dogmatic: it rep- resents the most reliable conclusion that can be drawn on the basis of the available data. there are no certainties in the realm of science. this may seem profoundly disappointing to the general public, but it should not. science is a way of thinking much more than it is a body of knowledge. its true achievement is not pro- viding answers, but rather a method through which answers can be sought. a basic instrument of this method is rep- resented by probability theory. as peter coles brilliantly illustrates in his engaging new book, from cosmos to chaos, probability theory makes it possible to extract meaningful infor- mation from a sea of noisy data, to deal with intrinsically probabilistic processes, and to infer conclusions on the basis of incomplete information. after explaining the basics of probability theory, coles offers a ride across virtually the entire spectrum of the physical sciences, including thermodynamics, cosmology, chaos theory and quantum mechanics, as well as stimulating issues such as the anthropic principle and life on other worlds. each topic is considered from the specific perspective of how it involves, and is related to, the concept of probability. coles also examines the impact of probability on many aspects of everyday life. he shows us how the decisions of law courts and medical tests, as well as more mundane activities such as gambling strategies, may suffer deeply from an incorrect use of statistics. to illustrate how probability theory works, coles presents some intriguing and often surprising examples, encouraging readers to think for themselves and providing them with material to entertain and amaze their friends. i particularly appreciated the historical notes and lively anecdotes that highlight the famous and less well-known personalities who con- tributed to the development of the statistical approach to science. coles points out that most of these were astronomers. historically, men of science generally applied their talents to a range of disciplines, so most of the people cited in the book might also be considered as math- ematicians and physicists. a central chapter of the book is devoted to the controversy between the frequentist and the bayesian interpretations of probability. the former interprets probability as a frequency of occurrence in repeated experiments, whereas in the latter probability measures the degree of belief an individual has in an uncertain proposition. as coles openly declares, one of the book’s objectives is to argue in favour of the bayesian approach. pragmatically, the two interpretations should be considered as complementary, rather than competing. undoubtedly, bayesian inference has profound implications as it concerns critical thinking and may lead to a deeper understanding of the scientific method. however, the ability to develop a new hypothesis or theory relies in the end on scientists’ creativity, something that can hardly be delimited within a methodological framework. i have a minor observation. randomness, which is intrinsically related to probability, deserves a more detailed discussion than is given here. in particular, the monte carlo method is mentioned only briefly, despite its importance and wide use in virtually every branch of science. altogether, the book provides a truly enjoy- able overview of the role of probability in sci- ence, as well as in everyday life. it is aimed essentially at non-specialist readers, but even those who are familiar with its contents will enjoy the stimulating presentation. finally, i fully endorse coles’ passionate plea at the end of the book for a better integration of sci- ence and society. to face challenges such as large-scale pollution, the energy crisis or food shortages, we will need all the instruments that science puts at our disposal. perhaps an even greater threat is represented by fundamental- isms of any kind (religious, political, economi- cal) that aim to impose their dogmas on the whole of society. science, or rather, the forma mentis it gives us, may offer the best antidote for defying them. ■ gianpietro malescio is in the department of physics, university of messina, messina, italy. nature|vol | october autumn books nature publishinggroup © 	coping with uncertainty shieldsquare captcha we apologize for the inconvenience... ...but your activity and behavior on this site made us think that you are a bot. note: a number of things could be going on here. 	if you are attempting to access this site using an anonymous private/proxy network, please disable that and try accessing site again. 	due to previously detected malicious behavior which originated from the network you're using, please request unblock to site. please solve this captcha to request unblock to the website 	 		you reached this page when trying to access 		https://iopscience.iop.org/journal/ - from 		 . . . on 		april , : : utc 	 e d i t o r i a l know your injm editor in-chief (april- ) vipin chandra kalia � association of microbiologists of india he is presently chief scientist, microbial biotechnology and genomics, csir—institute of genomics and integra- tive biology, delhi, is a graduate in botany from univer- sity of delhi and did his msc and phd in genetics, from indian agricultural research institute, new delhi. his main areas of research include microbial biodiversity, bioenergy, biopolymers and genomics. his works have been well acknowledged in the areas of bacterial diversity, genomics, taxonomy, horizontal gene transfer, quorum sensing and quenching. his recent efforts have been concentrated towards providing bacteria with abilities to produce biomolecules having potential to be used for treating cancer, diabetes, infectious and inflammatory diseases. the work supported by department of biotechnology, government of india is being carried forward by industry. his group has made contributions in understanding metabolic pathways leading to reduction in environmental pollution through complete degradation of biowastes with concomitant production of bioenergy (hydrogen) and biopolymers (bioplastics). his innovative research works are targeted towards efficient economical and eco-friendly approaches to societal problems espe- cially waste management and energy crisis. dr. kalia has published nearly articles in leading international jour- nals with high impact factor and has patents to his credit, including those granted in usa and uk. he has guided students for their phd and a few hundred post- graduate students. he has travelled across the globe as visiting professor and as research scientist to several institutes and universities. he is a fellow of several sci- entific societies and served various committees including national scientific advisory committee member of the department of biotechnology, government of india. he is associated with several international journals as editor and reviewer. he has been a life member of association of microbiologists of india (ami) since , participated in ami conferences and activities. since , he has been editor and associate editor of indian journal of microbi- ology (ijm). it is with pride we state that in view of his excellent contributions made in the field of microbial genomics and microbial biotechnology, dr. kalia has been awarded the fellowship of ami since . v. c. kalia (&) csir—institute of genomics and integrative biology, delhi, india e-mail: vckalia@igib.res.in indian j microbiol (jan–mar ) ( ): doi . /s - - - 	know your injm editor in-chief (april- ) optimisation of a novel resorption cogeneration using mass and heat recovery energy procedia ( ) – available online at www.sciencedirect.com sciencedirect - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of icae doi: . /j.egypro. . . * corresponding author. tel.:+ ( ) - - e-mail address: y.j.lu@ncl.ac.uk the th international conference on applied energy – icae optimisation of a novel resorption cogeneration using mass and heat recovery yiji lua,*, huashan baoa, ye yuana, yaodong wanga, liwei wangb, anthony paul roskillya asir joseph swan centre for energy research, newcastle university, newcastle ne ru, uk. binstitute of refrigeration and cryogenics, shanghai jiao tong university, shanghai, , china; abstract the paper proposed an optimised resorption cogeneration with a stabilisation unit and effective mass and heat recovery to further improve the performance of the original resorption cogeneration first proposed by liwei wang et al. it combines the ammonia resorption technology and expansion machine to utilise low grade heat such as solar energy or waste heat for continuous and simultaneous production of refrigeration and electricity. it has been theoretically proved competent to improve the overall exergy efficiency by %- % compared with goswami cycle under the same working conditions. in this work, a buffer was designed to place before the expansion machine to mitigate the dramatically varying reaction rate, and two sets of resorption cycle were arranged to overcome the intermittent performance of the chemisorption. the cycle was investigated based on the first and second law of thermodynamics using engineering equation solver. twelve resorption working pairs of salt complex candidates were analysed under different working conditions. the energy and exergy analysis identified the ideal working pair among the chosen working pairs under the driven temperature from k to k. © the authors. published by elsevier ltd. selection and/or peer-review under responsibility of icae keywords: resorption cogeneration, refrigeration electricity, first law analysis, second law analysis . introduction with the growing concerns of energy crisis, using low-grade heat such as solar energy, industrial waste heat, etc. attracts growing attentions to reduce the energy consumption of the conventional energy. the rankine cycle is one of the choices to produce extra work from low-grade heat. however, the performance of rankine cycle cannot match the variable temperature of the heat source because of its single working fluid. the kalina cycle was first proposed by kalina [ ] to solve this problem by using ammonia-water mixture as working fluid. in comparison with the simple rankine cycle, the kalina cycle _________ © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of icae core metadata, citation and similar papers at core.ac.uk provided by elsevier - publisher connector https://core.ac.uk/display/ ?utm_source=pdf&utm_medium=banner&utm_campaign=pdf-decoration-v http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf yiji lu et al. / energy procedia ( ) – can produce up to % more power from the industrial waste heat and show higher exergy efficiency when the heat source temperature is below oc[ ]. goswami developed the kalina cycle into a combined power and refrigeration cycle, which can supply power and refrigeration constantly in a loop. however, the goswami cycle suffers from its poor performance of cooling generation[ ]. the novel resorption cogeneration was first proposed by liwei wang et al[ ], which also aimed at producing power and refrigeration simultaneously. the wide selection of chloride salts which can reversibly react with ammonia allows the resorption cogeneration being powered by various temperature sources. nevertheless, the chemisorption technology cannot supply stable pressure to the expansion machine like the absorption technology does, which will reduce the performance of power generation. in this paper, a buffer was added before the expansion machine to maintain stable pressure supply and two sets of resorption cogeneration were designed to overcome the intermittent performance of the chemisorption. furthermore, mass and heat recovery has also been applied to further improve the performance. . optimised resorption cogeneration fig. . diagram of the novel resorption cogeneration cycle with mass and heat recovery the resorption cogeneration mainly contains two high temperature salt (hts) beds, two low temperature salt (lts) beds, two heat exchangers, one buffer and one expander, which is shown in fig. .  step -left side power; right side refrigeration, close v , v , v , v ; open v , v , v when hts is heated by the heat source, the desorbed ammonia flows into the buffer where the ammonia remains at saturated state. the vapour phase of ammonia passes through the expander and is adsorbed by the lts . the adsorption heat is rejected to the environment from lts . on the other side, the cooling production can be obtained when hts adsorbs the ammonia from lts . the heat exchanger and are designed to recover the heat from the hts and expander , respectively, and in some case increase the system performance.  step -mass recovery, close v , v , v , v open v , v and close v for about -minute. and then close v , v and open v .  step -left side refrigeration; right side power, close v , v v , v ; open v , v , v  step -mass recovery, close v , v , v , v open v , v and close v for about -minute. and then close v , v and open v . yiji lu et al. / energy procedia ( ) – apply the same as step . repeat from step to step , the resorption cogeneration can supply power and refrigeration consecutively. . analysis of the resorption cogeneration the equilibrium reaction lines and thermodynamic features of the resorption cogeneration is shown in fig. . b-c is the heating process of the ammonia desorbed from lts. the isentropic expansion process in expander is shown as c-d and d-a is a part of the equilibrium reaction line of lts. the refrigeration production of the resorption cogeneration is obtained form a-b. the energy and exergy efficiency of twelve resorption working pairs have been compared under the driven temperature from k to k. the chosen salts are as follows, hts- (mncl , fecl , nicl ) and lts- (pbcl , bacl , cacl ,srcl ). fig. . schematic clausius-clapeyron diagram of the resorption cogeneration . results and discussions yiji lu et al. / energy procedia ( ) – fig. . cop, power efficiency and exergy efficiency of the resorption cogeneration the analysis on this resorption cogeneration is conducted based on first and second law analysis to identify the best resorption working pair for the heat source ranging from k to k. results show the cop of the system decreases and the power efficiency increases with the increase of heating temperature, which means this cycle can meet different user needs under different supply temperature. the working pair srcl -mncl shows the best performance among the twelve candidates and achieves the highest exergy efficiency at . at the temperature of k. in this cogeneration, pbcl is not suggested to be used as lts, because its poor performance compare with the other chosen low temperature salts. in comparison with the formal resorption cogeneration the cop of the new system has been increased about . with the help of heat and mass recovery. . conclusion by adding a buffer in the system, this optimised resorption cogeneration can effectively combine the adsorption technology with the expansion machine to produce stable power output. according to the thermodynamic analysis, the srcl -mncl shows the best performance within the chosen working pairs by the heat source ranging from k to k. pbcl should always be avoided serving as lts in this cycle. compared to the formal resorption cogeneration, this optimised cycle increases the refrigeration production by the application of mass and heat recovery. this cogeneration shows a potential application prospect in remote and isolated area because of its low supply temperature, easy construction, dual energy generation, high cop production, etc. acknowledgement the authors would like to thank the uk engineering and physical science research council (epsrc) for the support of the research projects- lh cogen (ep/i / ) and global secure (ep/k / ). references [ ] kalina ai. combined cycle and waste-heat recovery power systems based on a novel thermodynamic energy cycle utilising low temperature heat for power generation. american society of mechanical engineers paper. ; -jpgc-gt- . [ ] zhang x, he m, zhang y. a review of research on the kalina cycle. renewable and sustainable energy reviews. ; : - . [ ] tamm g, goswami dy, lu s, hasan aa. theoretical and experimental investigation of an ammonia–water power and refrigeration thermodynamic cycle. solar energy. ; : - . [ ] wang l, ziegler f, roskilly ap, wang r, wang y. a resorption cycle for the cogeneration of electricity and refrigeration. applied energy. ; : - . [pdf] sensing and responding to hypoxia, molecular and physiological mechanisms | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /icb/ . . corpus id: sensing and responding to hypoxia, molecular and physiological mechanisms @inproceedings{lutz sensingar, title={sensing and responding to hypoxia, molecular and physiological mechanisms }, author={p. lutz and h. prentice}, booktitle={integrative and comparative biology}, year={ } } 	p. lutz, h. prentice 	published in integrative and comparative… 	biology, medicine abstract in order to adapt to low oxygen it is necessary first to be able to detect hypoxia, then to initiate the appropriate defense mechanisms. there are two basic detectors: molecular sensors that are directly linked to gene regulation and metabolic indicators that are triggered when the cell goes into a state of energy imbalance. the molecular responses to oxygen deprivation are characterized in a variety of cell types and include activation of oxygen sensors, signaling through specific… expand view on bioone academic.oup.com save to library create alert cite launch research feed share this paper citationshighly influential citations background citations view all topics from this paper 	oxygen 	hypoxia 	adenosine triphosphate 	potassium 	calcium 	erythrocytes 	blood cells 	brain 	chemoreceptor cells 	pathologic neovascularization 	transcript 	turtle 	structure of parenchyma of lung 	defense mechanisms 	anoxia 	respiration 	fos gene citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency title : oxygen sensors of the peripheral and central nervous system 	g. m. c. renshaw, m. nikinmaa 	chemistry 	 save alert research feed oxygen sensors of the peripheral and central nervous systems 	g. m. c. renshaw, m. nikinmaa 	medicine 	 	 	pdf save alert research feed oxygen sensors and energy sensors act synergistically to achieve a graded alteration in gene expression: consequences for assessing the level of neuroprotection in response to stressors. 	g. renshaw, joshua warburton, a. girjes 	biology, medicine 	frontiers in bioscience : a journal and virtual library 	 	 	highly influenced 	pdf 	view excerpts, cites background save alert research feed mitochondria-controlled signaling mechanisms of brain protection in hypoxia 	l. lukyanova, yulia i. kirova 	medicine, biology 	front. neurosci. 	 	 	 	view excerpt, cites background save alert research feed adenosine as a signal for ion channel arrest in anoxia-tolerant organisms. 	l. buck 	biology, medicine 	comparative biochemistry and physiology. part b, biochemistry & molecular biology 	 	 save alert research feed tissue response to different hypoxic 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(pcm) for thermal management experimental investigation and numerical simulation analysis on the thermal performance of a building roof incorporating phase change material (pcm) for thermal management a. pasupathy a, l. athanasius a, r. velraj a,*, r.v. seeniraj b a department of mechanical engineering, college of engineering, chennai , india b department of mechanical engineering, sri venkateswara college of engineering, sriperumpudur, tamilnadu, india received december ; accepted april available online may abstract thermal storage plays a major role in a wide variety of industrial, commercial and residential application when there is a mismatch between the supply and demand of energy. latent heat storage in a phase change material (pcm) is very attractive, because of its high- energy storage density and its isothermal behavior during the phase change process. several promising developments are taking place in the field of thermal storage using phase change materials (pcm) in buildings. it has been demonstrated that for the development of a latent heat storage system (lhts) in a building fabric, the choice of the pcm plays an important role in addition to heat transfer mech- anism in the pcm. increasing the thermal storage capacity of a building can enhance human comfort by decreasing the frequency of internal air temperature swings, so that the indoor air temperature is closer to the desired temperature for a longer period of time. this paper attempts to study the thermal performance of an inorganic eutectic pcm based thermal storage system for thermal management in a residential building. the system has been analyzed by theoretical and experimental investigation. experiments are also conducted by circulating water through the tubes kept inside the pcm panel to test its suitability for the summer months. in order to achieve the opti- mum design for the selected location, several simulation runs are made for the average ambient conditions for all the months in a year and for the various other parameters of interest. � elsevier ltd. all rights reserved. keywords: latent heat thermal energy storage; space heating and cooling; building energy conservation; phase change material; encapsulation . introduction scientists all over the world are in search of new and renewable energy sources. one of the options is to develop energy storage devices, which are as important as develop- ing new sources of energy. thermal energy storage systems provide the potential to attain energy savings, which in turn reduce the environment impact related to non-renew- able energy use. in fact, these systems provide a valuable solution for correcting the mismatch that is often found between the supply and demand of energy. latent heat storage is a relatively new area of study although it previ- ously received much attention during the energy crisis of late ’s and early ’s where it was extensively researched for use in solar heating systems. when the energy crisis subsided, much less emphasis was put on latent heat storage. although research into latent heat stor- age for solar heating systems continues, recently it is increasingly being considered for waste heat recovery, load leveling for power generation, building energy conservation and air conditioning applications. as demand for air conditioning increased greatly during the last decade, large demands of electric power and limited reserves of fossil fuels have led to a surge in interest with regard to energy efficiency. electrical energy consumption - /$ - see front matter � elsevier ltd. all rights reserved. doi: . /j.applthermaleng. . . * corresponding author. tel.: + ; fax: + . e-mail addresses: pasu @gmail.com (a. pasupathy), athanasius@ sify.com (l. athanasius), velrajr@annauniv.edu (r. velraj), seenirajr@ hotmail.com (r.v. seeniraj). www.elsevier.com/locate/apthermeng available online at www.sciencedirect.com applied thermal engineering ( ) – mailto:pasu @gmail.com mailto:athanasius@sify.com mailto:athanasius@sify.com mailto:velrajr@annauniv.edu mailto:seenirajr@hotmail.com mailto:seenirajr@hotmail.com varies significantly during the day and night according to the demand by industrial, commercial and residential activ- ities. in hot and cold climate countries, the major part of the load variation is due to air conditioning and domestic space heating, respectively. this variation leads to a differ- ential pricing system for peak and off peak periods of energy use. better power generation/distribution manage- ment and significant economic benefit can be achieved if some of the peak load could be shifted to the off peak load period. this can be achieved by thermal energy storage for heating and cooling in residential and commercial building establishments. there are several promising developments going on in the field of application of pcms for heating and cooling of building. zalba et al. [ ] performed a detailed review on thermal energy storage that dealt with phase change materials, heat transfer studies and applications. farid et al. [ ] also presented a review on the analysis of phase change materials, hermetic encapsulation and application of pcms. mehling and hiebler [ ] summarized the investi- gations and developments on using pcms in buildings. murat kenisarin and khamid mahkamov [ ] presented a review of investigations and developments carried out dur- ing the last – years in the field of phase change mate- rials, enhancing heat conductivity, available fields of using pcm, and clarifying typical questions. arkar and medved [ ], stritih and novak [ ] designed and tested a latent heat storage system used to provide ven- tilation of a building. the results of their work, according to the authors, were very promising. phase change dry wall or wallboard is an exciting type of building integrated heat storage material. several authors investigated the various methods of impregnating gypsum and other pcms [ – ] in wallboards. limited analytical studies of pcm wall- board have been conducted, but few general rules pertain- ing to the thermal dynamics of pcm wallboard are available. lee et al. [ ] and hawes et al. [ ] presented the ther- mal performance of pcm’s in different types of concrete blocks. they studied and presented the effects of concrete alkalinity, temperature, immersion time and pcm dilution on pcm absorption during the impregnation process. wood lightweight concrete is a mixture of cement, wood chips or saw dust, which should not exceed % by weight, water and additives. this mixture can be applied for building interior and outer wall construction. for inte- gration in wood lightweight concrete, two pcm materials rubitherm gr , – mm and gr , . – . mm were investigated by mehling et al. [ ]. meng zhang et al. [ ] presented the development of a thermally enhanced frame wall that reduces peak air conditioning demand in residential buildings. ismail et al. [ ] proposed a different concept for thermally effective windows using a pcm moving curtain. unisa (university of south australia) [ ] developed a roof-integrated solar air heating/storage system, which uses existing corrugated iron roof sheets as a solar collector for heating air. kunping lina et al. [ ] put forward a new kind of under-floor electric heating system with shape-sta- bilized phase change material (pcm) plates. hed [ ] investigated pcm integrated cooling systems for building types where there is an over production of heat during the daytime such as offices, schools and shopping centers. free cooling was investigated at the university of zara- goza/spain by zalba [ ]. the objective of the work was to design and construct an experimental installation to study pcms with a melting temperature between and �c. nomenclature c , c specific heat of roof top slab and concrete slab (kj/kg k) cpl specific heat of liquid pcm (kj/kg k) cps specific heat of solid pcm (kj/kg k) f implicit factor grl grashof number hi inside heat transfer coefficient (w/m k) ho outside heat transfer coefficient (w/m k) k , k , k thermal conductivity of roof top slab, pcm panel and bottom concrete slab (w/m k) l , l , l thickness of roof top slab, pcm panel and bottom concrete slab (m) nul nusselt number pr prandle number qrad radiation flux (w/m ) re reynolds number t temperature (�c) t ambient temperature (�c) t i previous time step temperature at ith volume cell (�c) ti current time step temperature at ith volume cell (�c) tin initial temperature (�c) troom room temperature (�c) ts surface temperature (�c) tsky sky temperature (�c) a absorptivity emissivity hsl solid–liquid enthalpy change (kj/kg) r stefan boltzmann constant q , q , q density of roof top slab, pcm panel and bot- tom concrete slab (kg/m ) dt time step (s) dx , dx , dx nodal distances (m) dx , dx , dx control volume length of roof top slab, pcm panel, bottom concrete slab (m) a. pasupathy et al. / applied thermal engineering ( ) – https://isiarticles.com/article/ dual battery storage system: an optimized strategy for the utilization of renewable photovoltaic energy in the united kingdom electronics article dual battery storage system: an optimized strategy for the utilization of renewable photovoltaic energy in the united kingdom sarvar hussain nengroo , muhammad ahmad kamran , muhammad umair ali , do-hyun kim , min-soo kim , altaf hussain and hee jee kim ,* department of electrical engineering, pusan national university, busandaehak-ro beon-gil , busan , korea; ssarvarhussain@gmail.com (s.h.n.); umairali.m @gmail.com (m.u.a.); kdh @naver.com (d.-h.k.); rlaalstn @naver.com (m.-s.k.); ahussain @outlook.com (a.h.) department of cogno-mechatronics engineering, pusan national university, busandaehak-ro beon-gil , busan , korea; malik.pieas@gmail.com * correspondence: heeje@pusan.ac.kr; tel.: + - - - received: august ; accepted: september ; published: september ���������� ������� abstract: the increasing world human population has given rise to the current energy crisis and impending global warming. to meet the international environmental obligations, alternative technological advances have been made to harvest clean and renewable energy. the solar photovoltaics (pv) system is a relatively new concept of clean technology that can be employed as an autonomous power source for a range of off-grid applications. in this study, the dual battery storage system is coupled with a solar pv system and a low voltage grid, benefitting from the feed-in tariff (fit) policy. the main outcomes of this study are: (i) a novel dual battery storage system for the optimal use of the pv system/energy is proposed; (ii) the problem is formulated in the form of a mathematical model, and a cost function is devised for effective cost calculation; (iii) an optimal cost analysis is presented for the effective use of pv energy; (iv) real-time data of a solar pv taken from the owner and the demand profile collected from the user is applied to the proposed approach, with united kingdom (uk) tariff incentives. this system works in a loop by charging one system from the solar pv for one day, and discharging the other system. this model gives certainty that power is exported to the grid when the solar pv generates an excess amount; batteries are utilized during the peak hours, and power is purchased when the demand is not met by the batteries, or when the demand is higher than the generation. this study examined the economic knowledge of solar pv and battery storage systems by considering the fit incentives. keywords: solar pv; feed-in tariff; battery storage system; demand profile . introduction . . energy spread and photovoltaic technology/pv energy and world demand the increase in energy demand of developing countries is expected to be % by , indicating the emerging growth, prosperity, and developing economies of such areas [ ]. in contrast, the energy demand in the world will increase to % with the increase in population. the intergovernmental panel on climate change (ipcc) shows that there has been a %, %, and % increase in the concentrations of co , methane, and nitrous oxide, respectively, since pre-industrial times. as of , two-thirds of global co emissions are produced by the combustion of fuel, of which electricity generates %. a considerable amount of anthropogenic greenhouse gases are released from the industrial zones (iz) in different countries [ ]. the detrimental effects of the unsustainable electronics , , ; doi: . /electronics www.mdpi.com/journal/electronics http://www.mdpi.com/journal/electronics http://www.mdpi.com https://orcid.org/ - - - https://orcid.org/ - - - http://www.mdpi.com/ - / / / ?type=check_update&version= http://dx.doi.org/ . /electronics http://www.mdpi.com/journal/electronics electronics , , of patterns of energy on social, health and environmental have been reported in [ – ]. according to [ ], it is economically and technically feasible for renewable energy technologies (rets) to be an alternate source for the present fossil fuel electricity infrastructure. the international energy agency (iea) reported that the total installed capacity of the solar photovoltaics (pv) system in was gw, which was ramped up by five times to gw in , followed by an increase in capacity to gw in . in , the total global pv capacity was gw, with gw from european union (eu), . gw from china, . gw from japan, and . gw from united states of america (usa) [ – ]. of all the electricity produced in the world in from the renewable energy sources, which amounts to . %, the share of electricity from the pv is . %. advances in science and technology have provided several alternative means of producing energy on a sustainable level [ ]. more attention is being paid towards pv technology, due to the decrease in the cost of pv modules, the long lifetime service, and the widely flexible applications [ , ]. the solar panels consist of a number of pv modules, which convert solar energy into electrical energy [ – ]. different types of commonly used materials for pv modules nowadays include mainly monocrystalline, polycrystalline, and thin film technologies [ – ]. amorphous silicon technology is thin film technology, which is low-cost and the most environmentally friendly, and its cost can be as low as to . – . €/wp [ – ]. solar pv technology can be considered as a backbone to shift our conventional energy sources to renewable and sustainable energy sources. the earth receives approximately × tw hr energy from the sun each year, which equals to potentially around times more than the energy demand of the world [ ]. pv energy and energy efficiency play a key role in global energy usage. a common example of this are solar street lighting systems. they reduce the load of the conventional energy system and are an important contributor to improve the energy efficiency. pinter et al. [ ], investigated the economic analysis of the installation of a solar pv system for street lighting purposes in a hungarian village comprising of – residents, and encouraged the deployment of the pv system. . . energy storage and its effective utilization the sporadic nature of pv systems is the main drawback in matching intermittent energy production with load demand. to overcome this drawback, a hybrid system is utilized, which consists of solar pv and a dual energy storage system connected with load [ , ]. the installation of the hybrid pv and energy storage system is economically feasible to meet the consumer load demand, as more generating capacity uses solar and wind energy [ ]. nizetic et al. [ ], investigated the design and performance of the hybrid system for different operating conditions, with the conclusion that the hybrid system can be a cost-effective solution for small- and medium-scale applications. energy storage system (ess) refers to a transformation of electrical energy from a power network or renewable energy sources (res) into a form that can be stored and utilized during peak hours, or when the generating source is unavailable. according to [ – ], large-scale energy storage technologies, such as thermal storage, pumped hydro storage, fuel cell storage, and supercapacitors, have financial and technical problems. currently, the battery energy storage system (bess) is the main focus, because of the ease of installation compared to other storage technologies [ ]. the analysis of the study in [ ] shows that the optimal management of hybrid pv and bess connected with the utility grid resulted in reduced electricity costs. the study of the work in [ ], developed a technology selection and operation (tso) optimization model to find out the optimal selection of pv and battery systems in the commercial buildings. a multi-period mixed-integer linear program (milp) model for the scheduling and planning of the pv-battery storage system to magnify the net cash flow was studied in [ , ]. the optimal flow of power management for the distributed energy resources with batteries to meet the consumer demand at low cost was presented in [ , ]. pamparana et al. [ ], developed a novel milp model to optimize the operational costs of the induction of pv and battery energy storage with a semi-autogenous grinding mill. the advantages of the operational planning of electronics , , of nonconventional sources (wind power and pv) and the ess has been discussed in [ , ]. the uptake of solar pv and bess, and its profitability, is likely to eliminate dependence on power from the grid, and make independent homes or microgrids a possibility [ ]. . . batteries and feed-in-tariff incentives/effective cost, and the impact of the pv system nevertheless, most of the available literature in this area neglected the cost evaluation of tariff incentives. the operational planning of nonconventional sources (wind power and pv) and ess has been discussed in. the use of batteries with pv systems to increase the self-consumption of electricity has expanded, particularly in germany, japan, australia, and the usa [ , ]. thus far, the batteries used in power system applications are deep cycle batteries (lithium-ion, lead-acid, flooded type, valve regulated type, sodium sulfur, metal ion, lithium-iron-phosphate, and flow batteries) having energy capacity in the range of to mwh and efficiencies of approximately – % [ ]. lithium-ion batteries are used most frequently with the pv system [ ]. lithium-ion batteries are promising technology because of their high reliability, high energy density, low toxicity, high reliability, high efficiency, and long-life cycle [ , ]. the average cycle stability based on the depth of discharge (dod) for lithium-ion is ( % dod) and for the olivine-type-lifepo , is , ( % dod) [ ]. a feed-in tariff (fit) is a scheme for the deployment of renewable energy technologies to support renewable energy producers by offering long-term purchase agreements [ – ]. according to [ ], fit policies have led to the establishment of more than , mw of pv power and more than , mw of wind power from to in the european union (eu), and are responsible for approximately % and % of global pv and wind deployment, respectively. the usa was the first country that considered the public utility regulatory policies act (purpa) in , which was based on the purchase of electricity generated from the renewable energy facilities at pre-established rates. in , germany’s electricity feed-in law implemented the stromeinspeisungsgesetz (streg) policy to purchase electricity from the non-utility renewable energy generators at a fixed percentage of retail electricity [ ]. the current need is to move away from non-replenishing energy sources, which pollute the environment by releasing large amounts of co gases, towards the environmentally sustainable plants to mitigate the energy crisis, mainly in the power sector. the induction of batteries with a solar pv system serves as an alternate solution for the reduction of greenhouse gases, and to tackle peak shaving. many different master plans have been developed to make use of pv energy with optimal results. previous studies [ , ] have examined the fruitful techno-economic analysis of integration of solar pv and battery storage systems as an independent power source to tackle the peak demand. in the proposed setup, two batteries were managed smartly by charging one system from the solar pv, while the other is used to meet the demand, and the process and charging and discharging is switched to make use of the system optimally. the capacity of the pv generating system is kw and the capacity of each battery used in our proposed optimized model is ah. a mathematical model is devised for this system to determine the optimal cost for the proposed system. . material and methods . . problem formulation the increasing demand for energy has prompted several research groups to evaluate different renewable energy resources as a whole or as a share. solar energy is one of the cheapest and easiest way to generate electricity to mitigate the energy crisis. on the other hand, the generation of electricity from solar energy is not continuous within a certain threshold, and has become a bottleneck depending upon the time of day, the thermal–environmental conditions, and the duration of light. therefore, it can be regarded as a variable generator source throughout the year. consequently, the generation capacity of a solar energy source sometimes leads or lags the demand, as shown in figure . electronics , , of electronics , , x for peer review of figure . per unit power profile of solar photovoltaics (pv) generation and the load of different days in a year. the plots were taken for the different months of the year. in this figure, the blue lines show the generation of solar pv and the purple lines show the demand profile of the consumer. the plots in the top row from left to right were taken on and december, and the plot on the left of the second row was taken on january, which indicates that solar pv generation lagged in demand, and power were provided by the grid also to fulfil the demand. the plots in the right of the second row were taken on may, and the plots on the lower row were taken on june, and on july, indicating an excess of solar pv generation with respect to demand, which is exploited to charge batteries. the extra power was shifted to the grid utility when the charge in the batteries reached the maximum. this pattern showed that a solar plant can deliver power for an onsite load, it can export power when it exceeds the demand of certain area, and it can purchase electricity from the grid to supply a particular area during the time with less solar generation. therefore, a mathematical function catering to this variability in the requirement of a solar energy unit is presented in equation ( ). in this study, a cost function j is defined to represent the revenue generated by the solar panels: 𝐽 = 𝑚𝑎𝑥 ∑[𝑃𝑔(𝑑, 𝑡) × 𝑝𝑔_𝐹𝐼𝑇 + 𝑃𝑒 (𝑑, 𝑡) × 𝑝𝑒_𝐹𝐼𝑇 − 𝑃𝑖 (𝑑, 𝑡) × 𝑝𝑖_𝐹𝐼𝑇 ] 𝑑,𝑡 × ∆𝑡 ( ) where 𝑑 represents the date of the year, 𝑡 represents the specific time of the day, 𝑃𝑔 is the generation power from the solar plant, 𝑝𝑔_𝐹𝐼𝑇 is the generation tariff, 𝑃𝑒 is the excess power, i.e., the difference of generation and demand, 𝑝𝑒_𝐹𝐼𝑇 is the export tariff, 𝑃𝑖 represents the power required by the grid to feed the load during unmet demand, and 𝑝𝑖_𝐹𝐼𝑇 is the import tariff rate. this paper proposes the idea of utilizing two separate energy storage systems (batteries) s and s . the solar energy is stored in one storage unit, and the second one is used to deliver the power to a specific area for a specific time. in the second stage, the batteries are swapped; the first is used to supply power and the second is reserved for storage if excess power is generated. thus, this system works in the loop, which is shown in figure . figure . per unit power profile of solar photovoltaics (pv) generation and the load of different days in a year. the plots were taken for the different months of the year. in this figure, the blue lines show the generation of solar pv and the purple lines show the demand profile of the consumer. the plots in the top row from left to right were taken on and december, and the plot on the left of the second row was taken on january, which indicates that solar pv generation lagged in demand, and power were provided by the grid also to fulfil the demand. the plots in the right of the second row were taken on may, and the plots on the lower row were taken on june, and on july, indicating an excess of solar pv generation with respect to demand, which is exploited to charge batteries. the extra power was shifted to the grid utility when the charge in the batteries reached the maximum. this pattern showed that a solar plant can deliver power for an onsite load, it can export power when it exceeds the demand of certain area, and it can purchase electricity from the grid to supply a particular area during the time with less solar generation. therefore, a mathematical function catering to this variability in the requirement of a solar energy unit is presented in equation ( ). in this study, a cost function j is defined to represent the revenue generated by the solar panels: j = max ∑ d,t [ pg(d, t) × pg_f i t + pe(d, t) × pe_f i t − pi(d, t) × pi_f i t ] ∆ × t ( ) where d represents the date of the year, t represents the specific time of the day, pg is the generation power from the solar plant, pg_f i t is the generation tariff, pe is the excess power, i.e., the difference of generation and demand, pe_f i t is the export tariff, pi represents the power required by the grid to feed the load during unmet demand, and pi_f i t is the import tariff rate. this paper proposes the idea of utilizing two separate energy storage systems (batteries) s and s . the solar energy is stored in one storage unit, and the second one is used to deliver the power to a specific area for a specific time. in the second stage, the batteries are swapped; the first is used to supply power and the second is reserved for storage if excess power is generated. thus, this system works in the loop, which is shown in figure . electronics , , of electronics , , x for peer review of figure . schematic of charging and discharging for two energy centres, s and s . overall, despite the increase in capital cost, the overall cost decreases. the cost function, j , is defined as: 𝐽 = 𝑚𝑎𝑥 ∑ [ 𝑃𝑔(𝑑, 𝑡) × 𝑝𝑔_𝐹𝐼𝑇 + 𝑃 𝑖𝑛(𝑑, 𝑡) × 𝑝𝑖𝑛_𝐹𝐼𝑇 + 𝑃 𝑖𝑛(𝑑, 𝑡) × 𝑝𝑖𝑛_𝐹𝐼𝑇 + 𝑃 𝑜𝑢𝑡 (𝑑, 𝑡) × 𝑝𝑜_𝐹𝐼𝑇 +𝑃 𝑜𝑢𝑡 (𝑑, 𝑡) × 𝑝𝑜_𝐹𝐼𝑇 + 𝑃𝑒 (𝑑, 𝑡) × 𝑝𝑒_𝐹𝐼𝑇 − 𝑃𝑖 (𝑑, 𝑡) × 𝑝𝑖_𝐹𝐼𝑇 ] 𝑑,𝑡 × ∆𝑡 ( ) subjected to: 𝑃𝑖 (𝑑, 𝑡) ≥ , 𝑜 ≤ 𝑚𝑛𝑐 (𝑠𝑘 ) ≤ 𝑃𝑘 𝑖𝑛 𝑘 = , , 𝑜 ≤ 𝑃𝑘 𝑜𝑢𝑡 ≤ 𝑚𝑥𝑐 (𝑠𝑘 ) 𝑘 = , , where 𝑃𝑘 𝑖𝑛 and 𝑃𝑘 𝑜𝑢𝑡 represent the power that is used to store and to feed in, respectively, for the storage unit 𝑘 = , ; 𝑚𝑥𝑐 (𝑠𝑘 ) and 𝑚𝑛𝑐 (𝑠𝑘) represent the maximum and minimum storage capacities, respectively, and 𝑃𝑖 represents the power that is imported from the grid, 𝑃𝑒 represents the power excess power that is exported to the grid. . . methodological detail in the united kingdom (uk), there are various means, such as reduced value-added tax (vat), capital grants for householders, and schemes like renewable obligation (ro), and feed-in-tariff to embrace these microgeneration technologies [ ]. this paper examines the deployment of batteries with the pv system under fit incentives and time-varying electricity tariffs with the aim to reduce electricity bills. figure shows the power flows to the load from the utility grid, coupled with the pv and the energy storage system. the equipment and materials used for the flexible storage system include: pv modules, pv-inverters, a battery-inverter, a battery, a frame on the roof, cables, and outlets [ ]. solar pv modules consist of an assembly of solar pv cells, which convert the solar energy into direct current (dc) through the photovoltaic effect. the dc current was inverted by the power electronic inverter into alternating current (ac) to feed the load. the solar pv power was utilized onsite to provide power to the load. when there is excess power, it is prioritized by storing the power in the batteries first, until the batteries reach the maximum state of charge (soc). the surplus power is then exported to the grid at the prescribed export tariff. the batteries are employed to backup to meet the demand, if the demand is not met by the solar system. when the soc of the batteries falls below the prescribed limit, the power from the battery is curtailed and the power is imported from the grid at the described tariff. figure . schematic of charging and discharging for two energy centres, s and s . overall, despite the increase in capital cost, the overall cost decreases. the cost function, j , is defined as: j = max ∑ d,t [ pg(d, t) × pg_f i t + pin (d, t) × pin_f i t + p in (d, t) × pin_f i t + p out (d, t) × po_f i t +pout (d, t) × po_f i t + pe(d, t) × pe_f i t − pi(d, t) × pi_f i t ] × ∆t ( ) subjected to: pi(d, t) ≥ , o ≤ mnc(sk) ≤ pink k = , , o ≤ poutk ≤ mxc(sk) k = , , where pink and p out k represent the power that is used to store and to feed in, respectively, for the storage unit k = , ; mxc(sk) and mnc(sk) represent the maximum and minimum storage capacities, respectively, and pi represents the power that is imported from the grid, pe represents the power excess power that is exported to the grid. . . methodological detail in the united kingdom (uk), there are various means, such as reduced value-added tax (vat), capital grants for householders, and schemes like renewable obligation (ro), and feed-in-tariff to embrace these microgeneration technologies [ ]. this paper examines the deployment of batteries with the pv system under fit incentives and time-varying electricity tariffs with the aim to reduce electricity bills. figure shows the power flows to the load from the utility grid, coupled with the pv and the energy storage system. the equipment and materials used for the flexible storage system include: pv modules, pv-inverters, a battery-inverter, a battery, a frame on the roof, cables, and outlets [ ]. solar pv modules consist of an assembly of solar pv cells, which convert the solar energy into direct current (dc) through the photovoltaic effect. the dc current was inverted by the power electronic inverter into alternating current (ac) to feed the load. the solar pv power was utilized onsite to provide power to the load. when there is excess power, it is prioritized by storing the power in the batteries first, until the batteries reach the maximum state of charge (soc). the surplus power is then exported to the grid at the prescribed export tariff. the batteries are employed to backup to meet the demand, if the demand is not met by the solar system. when the soc of the batteries falls below the prescribed limit, the power from the battery is curtailed and the power is imported from the grid at the described tariff. electronics , , of electronics , , x for peer review of figure . schematic of the photovoltaic and battery storage systems (bess). figure shows the implementation of two batteries with a pv system and a utility grid. in this system, different tariff schemes were implemented to generate electricity from the pv panels, to store the excess power in the batteries, and to meet the unmet demand, which is provided by the grid, where cg is the generation tariff in £/kwh; cs is the rate in £/kwh at which storage, s , is charged; cs is the rate in £/kwh at which storage, s , is charged; cr is the retail tariff in £/kwh met by the storage, s ; cr is the retail tariff in £/kwh met by the storage, s ; cgr is the tariff in £/kwh at which power is imported from the grid to meet the demand, and ce is the tariff at which power is exported to the grid. figure . implementation of two batteries with the pv system and utility grid. . . tariff details . . . the time-of-use tariff the time-of-use (tou) tariff is an alternative way to tackle the energy storage (es) problem and provides opportunities for es advancement. in the tou tariff, there is a hike in the electricity cost figure . schematic of the photovoltaic and battery storage systems (bess). figure shows the implementation of two batteries with a pv system and a utility grid. in this system, different tariff schemes were implemented to generate electricity from the pv panels, to store the excess power in the batteries, and to meet the unmet demand, which is provided by the grid, where cg is the generation tariff in £/kwh; cs is the rate in £/kwh at which storage, s , is charged; cs is the rate in £/kwh at which storage, s , is charged; cr is the retail tariff in £/kwh met by the storage, s ; cr is the retail tariff in £/kwh met by the storage, s ; cgr is the tariff in £/kwh at which power is imported from the grid to meet the demand, and ce is the tariff at which power is exported to the grid. electronics , , x for peer review of figure . schematic of the photovoltaic and battery storage systems (bess). figure shows the implementation of two batteries with a pv system and a utility grid. in this system, different tariff schemes were implemented to generate electricity from the pv panels, to store the excess power in the batteries, and to meet the unmet demand, which is provided by the grid, where cg is the generation tariff in £/kwh; cs is the rate in £/kwh at which storage, s , is charged; cs is the rate in £/kwh at which storage, s , is charged; cr is the retail tariff in £/kwh met by the storage, s ; cr is the retail tariff in £/kwh met by the storage, s ; cgr is the tariff in £/kwh at which power is imported from the grid to meet the demand, and ce is the tariff at which power is exported to the grid. figure . implementation of two batteries with the pv system and utility grid. . . tariff details . . . the time-of-use tariff the time-of-use (tou) tariff is an alternative way to tackle the energy storage (es) problem and provides opportunities for es advancement. in the tou tariff, there is a hike in the electricity cost figure . implementation of two batteries with the pv system and utility grid. electronics , , of . . tariff details . . . the time-of-use tariff the time-of-use (tou) tariff is an alternative way to tackle the energy storage (es) problem and provides opportunities for es advancement. in the tou tariff, there is a hike in the electricity cost during peak hours but a lower cost during non-peak hours. by taking up the tou tariff, consumers can curtail inflated peak hours and switch to electricity during non-peak hours to reduce the energy crisis. with the closure of coal power plants, reducing the country’s carbon footprint has a great impact on the amounts of energy that the uk can generate. envisaging the energy shortages in the years to come, the tou tariff can play a key role in mitigating the demand and reducing the pressure on the uk energy infrastructure [ ]. a case study on the tou tariff has been done in some european countries, and in some states of the usa, such as the gulf power select program (gpsp), showing a % fall-off in electricity usage during peak hours [ ]. according to the statewide pricing pilot (spp) examined in california [ ], there is a decrease in the energy from . % to % during peak hours by implementing the tou tariff. in norway, there was an – % decrease in electricity use during the peak period by applying the tou tariff. . . . export tariff the export tariff allocates a revealed wage for every kilowatt-hour (kwh) of electricity exported, which is assigned by the authority. the generators in this system have a contract for the said period. this is beneficial to the consumers linked to this system for exporting the excess power to the utility grid. in this paper, the export tariff was fixed to . £/kwh. . . . import tariff power is imported from the grid when there is lack of solar pv generation to meet the unmet demand. electricity is imported from the grid at the prescribed rates. the half-hourly electricity readings were collected for the entire year from the elexon portal [ ]. the solar insolation data was gathered from the sheffield solar microgeneration database [ ]. in this model, the economy tariff [ ], was used as the time-of-use tariff, having a peak time period of h commencing from : to : , is levied at . . £/kwh, and the remaining time constituting the off-peak hours is charged at . £/kwh, as shown in figure . electronics , , x for peer review of during peak hours but a lower cost during non-peak hours. by taking up the tou tariff, consumers can curtail inflated peak hours and switch to electricity during non-peak hours to reduce the energy crisis. with the closure of coal power plants, reducing the country’s carbon footprint has a great impact on the amounts of energy that the uk can generate. envisaging the energy shortages in the years to come, the tou tariff can play a key role in mitigating the demand and reducing the pressure on the uk energy infrastructure [ ]. a case study on the tou tariff has been done in some european countries, and in some states of the usa, such as the gulf power select program (gpsp), showing a % fall-off in electricity usage during peak hours [ ]. according to the statewide pricing pilot (spp) examined in california [ ], there is a decrease in the energy from . % to % during peak hours by implementing the tou tariff. in norway, there was an – % decrease in electricity use during the peak period by applying the tou tariff. . . . export tariff the export tariff allocates a revealed wage for every kilowatt-hour (kwh) of electricity exported, which is assigned by the authority. the generators in this system have a contract for the said period. this is beneficial to the consumers linked to this system for exporting the excess power to the utility grid. in this paper, the export tariff was fixed to . £/kwh. . . . import tariff power is imported from the grid when there is lack of solar pv generation to meet the unmet demand. electricity is imported from the grid at the prescribed rates. the half-hourly electricity readings were collected for the entire year from the elexon portal [ ]. the solar insolation data was gathered from the sheffield solar microgeneration database [ ]. in this model, the economy tariff [ ], was used as the time-of-use tariff, having a peak time period of h commencing from : to : , is levied at . . £/kwh, and the remaining time constituting the off-peak hours is charged at . £/kwh, as shown in figure . figure . economy tariff. . results and discussion with the increase in technological development energy needs, and to overcome the concerns of global warming, researchers have begun to consider changing from limited and hazardous energy sources to environmentally compatible energy sources, such as solar pv. figure shows the solar pv generation and the demand profile of the consumers, for the various days of the different months. during the period of low pv, the purchase of power from the grid is figure . economy tariff. electronics , , of . results and discussion with the increase in technological development energy needs, and to overcome the concerns of global warming, researchers have begun to consider changing from limited and hazardous energy sources to environmentally compatible energy sources, such as solar pv. figure shows the solar pv generation and the demand profile of the consumers, for the various days of the different months. during the period of low pv, the purchase of power from the grid is required to meet the consumer demand. when the intensity of the solar irradiance is high, and the consumer demand is low, the power needed for the onsite demand is evaluated, and the remaining power is sold to the grid. there is significantly higher electricity generation in the summer, as shown in the lower middle and right plots in figure . the lower value of onsite demand allows us to charge the batteries according to the proposed methodology, and to export the remaining power at the prescribed export rate of . £/kwh. on the contrary, there is notably low pv generation and increased consumer demand during the winters as shown in the upper left and middle plots in figure . when the onsite consumer demand is greater than the pv generation, the batteries are utilized to supply power. the import of power from the grid is evaluated if the charge in the batteries to meet the demand reaches a minimum threshold level. figure shows the selection of the batteries for charging the first one on one day, and discharging the other for the other day. on the next day, the process is swapped by discharging the first one and charging the other, and this process works in a loop. figure reveals the pictorial view of our mathematical process, with a different rate for the generation, storage, export, and import of power. the demonstration of three cases has been studied as: . . case in this case, there is no solar pv or battery storage system feeding the consumer demand during the peak or non-peak hours. the demand is solely provided by the utility grid with the economy tariff applied. the power utilized to meet the demand is purchased at the rate of . £/kwh during the off-peak and at the rate of . £/kwh during peak hours. figure shows the grid-purchased electricity for the whole year, and recorded the highest demand of . kw in the month of january. table lists the cost of the electricity bought from the utility grid to meet the demand. electronics , , x for peer review of required to meet the consumer demand. when the intensity of the solar irradiance is high, and the consumer demand is low, the power needed for the onsite demand is evaluated, and the remaining power is sold to the grid. there is significantly higher electricity generation in the summer, as shown in the lower middle and right plots in figure . the lower value of onsite demand allows us to charge the batteries according to the proposed methodology, and to export the remaining power at the prescribed export rate of . £/kwh. on the contrary, there is notably low pv generation and increased consumer demand during the winters as shown in the upper left and middle plots in figure . when the onsite consumer demand is greater than the pv generation, the batteries are utilized to supply power. the import of power from the grid is evaluated if the charge in the batteries to meet the demand reaches a minimum threshold level. figure shows the selection of the batteries for charging the first one on one day, and discharging the other for the other day. on the next day, the process is swapped by discharging the first one and charging the other, and this process works in a loop. figure reveals the pictorial view of our mathematical process, with a different rate for the generation, storage, export, and import of power. the demonstration of three cases has been studied as: . . case in this case, there is no solar pv or battery storage system feeding the consumer demand during the peak or non-peak hours. the demand is solely provided by the utility grid with the economy tariff applied. the power utilized to meet the demand is purchased at the rate of . £/kwh during the off-peak and at the rate of . £/kwh during peak hours. figure shows the grid-purchased electricity for the whole year, and recorded the highest demand of . kw in the month of january. table lists the cost of the electricity bought from the utility grid to meet the demand. figure . power utilized without pv and battery system. . . case in this case, there is no battery storage, and the load is connected with the solar pv system and the utility grid directly. the load demand of the system is met by the pv system first. if the pv cannot meet the total load demand, then the remaining energy is imported from the grid at the economy tariff. when the pv system output is more than load demand, the remaining pv energy is exported to the grid at the prescribed export tariff of . £/kwh. figure shows the import and export profile for the entire year. table sums up the imported, exported, and net cost for this particular case. figure . power utilized without pv and battery system. . . case in this case, there is no battery storage, and the load is connected with the solar pv system and the utility grid directly. the load demand of the system is met by the pv system first. if the pv cannot meet the total load demand, then the remaining energy is imported from the grid at the economy tariff. when the pv system output is more than load demand, the remaining pv energy is exported to electronics , , of the grid at the prescribed export tariff of . £/kwh. figure shows the import and export profile for the entire year. table sums up the imported, exported, and net cost for this particular case.electronics , , x for peer review of figure . import and export of the power profile with solar pv and no battery. . . case in this case, the proposed hybrid pv and battery storage system is utilized. the batteries are charged and discharged according to the proposed methodology discussed above. figure shows the soc of both batteries for the whole year. when the battery soc reaches %, i.e., from day to day , the power is exported to the grid at prescribed export tariff, and if the soc of the battery decreases to its minimal level, i.e., from day to day and from day to day , the power is imported from the grid at the economy tariff. the battery discharge pattern is proposed in such a way that minimum power is imported during peak hours, which will decrease the cost of the electricity purchased. table shows the import, export, and net cost for the proposed methodology. figure . state of charge of the two batteries. table . results of cases , , and . case pv installed battery installed economy tariff applied cost of importing electricity (£) (a) cost of exporting electricity (£) (b) net value (£) (c = a − b) no no yes . nil . yes no yes . . . yes yes yes . . − . the table shows the cost analysis of three cases. in case , when no battery or pv was installed, the total cost of purchasing electricity was . £. in case , when the pv was installed, the cost of buying the electricity was . £ and the cost of selling the extra power was . £. in case , when both pv and batteries were employed, the cost of electricity purchase was . £ and the cost of selling the extra power was . £. the net value in case was − . £; the negative sign figure . import and export of the power profile with solar pv and no battery. . . case in this case, the proposed hybrid pv and battery storage system is utilized. the batteries are charged and discharged according to the proposed methodology discussed above. figure shows the soc of both batteries for the whole year. when the battery soc reaches %, i.e., from day to day , the power is exported to the grid at prescribed export tariff, and if the soc of the battery decreases to its minimal level, i.e., from day to day and from day to day , the power is imported from the grid at the economy tariff. the battery discharge pattern is proposed in such a way that minimum power is imported during peak hours, which will decrease the cost of the electricity purchased. table shows the import, export, and net cost for the proposed methodology. electronics , , x for peer review of figure . import and export of the power profile with solar pv and no battery. . . case in this case, the proposed hybrid pv and battery storage system is utilized. the batteries are charged and discharged according to the proposed methodology discussed above. figure shows the soc of both batteries for the whole year. when the battery soc reaches %, i.e., from day to day , the power is exported to the grid at prescribed export tariff, and if the soc of the battery decreases to its minimal level, i.e., from day to day and from day to day , the power is imported from the grid at the economy tariff. the battery discharge pattern is proposed in such a way that minimum power is imported during peak hours, which will decrease the cost of the electricity purchased. table shows the import, export, and net cost for the proposed methodology. figure . state of charge of the two batteries. table . results of cases , , and . case pv installed battery installed economy tariff applied cost of importing electricity (£) (a) cost of exporting electricity (£) (b) net value (£) (c = a − b) no no yes . nil . yes no yes . . . yes yes yes . . − . the table shows the cost analysis of three cases. in case , when no battery or pv was installed, the total cost of purchasing electricity was . £. in case , when the pv was installed, the cost of buying the electricity was . £ and the cost of selling the extra power was . £. in case , when both pv and batteries were employed, the cost of electricity purchase was . £ and the cost of selling the extra power was . £. the net value in case was − . £; the negative sign figure . state of charge of the two batteries. table . results of cases , , and . case pv installed battery installed economy tariff applied cost of importing electricity (£) (a) cost of exporting electricity (£) (b) net value (£) (c = a − b) no no yes . nil . yes no yes . . . yes yes yes . . − . electronics , , of the table shows the cost analysis of three cases. in case , when no battery or pv was installed, the total cost of purchasing electricity was . £. in case , when the pv was installed, the cost of buying the electricity was . £ and the cost of selling the extra power was . £. in case , when both pv and batteries were employed, the cost of electricity purchase was . £ and the cost of selling the extra power was . £. the net value in case was − . £; the negative sign indicated that the amount earned from the exported tariff was greater than the cost of the electricity imported. the statistical analysis of the scheme was examined for buying, selling or reserving the power for days. it is worthwhile to mention that some statistical parameters were added to analyze this study and its benefits in detail. a very interesting study by malvoni et al. [ ], discussed the forecasting of pv power generation using weather input data techniques. since the sporadic nature of weather conditions has a great impact on the pv system and their forecast, therefore, skewness and kurtosis would be important parameters that could define the probability distribution related to the import, export, and storage of power. the bigger values of kurtosis represent the narrow probability distribution and the smaller value correspond to a relatively flat distribution, and thus, a large number of small forecast errors [ ]. the skewness indicated that the forecasting of the model was over/under-forecast. the negative skewness represented the right-skewed distribution and the under-forecast model. on the contrary, positive skewness showed the left-skewed distribution and the over-forecast model. the skewness value near zero indicated the symmetric distribution. table shows the values of these statistical parameters, as described in [ ] for all the three cases. the values of the statistical parameters shown in table depict that the skewness was negative for all the three cases. in case , all of the electricity is fulfilled by the grid. in the early hours, the demand is relatively low, and as the day passes, the demand starts to increase. therefore, the probability distribution is right-skewed with negative skewness. in case , the initial demand is provided by the grid, but, as the day passes on, the solar pv system supports/shares the power demand generating the negative skewness for the import. but during midday, most of the demand is met by the solar pv system, and excess is transferred to the grid resulting in the delayed probability distribution. during the peak hours, the export is less right-skewed than the import. in case , the load demand is initially less, and energy is stored in the battery system for the peak hours. this is in keeping with the fact that during initial hours, the battery is fully charged based upon the previous day’s storage. therefore, the energy is exported initially, resulting in a lesser right-skewed probability distribution of export than the import and the storage. similarly, most of the demand in the early hours is fulfilled through the energy storage system. thus, the current-day storage slowly increases as per the available energy of the solar pv system, resulting in the right-skewed probability distribution. finally, as the most of the demand is met by the energy storage system, the import of power is required in the later hours of the day, resulting in a more right-skewed probability distribution of import. therefore, the skewness, in this case, is minimum. kurtosis in case shows that most of the demand is provided by the grid, which is comparatively less than case , as in case , some of the demand is shared by the solar pv system. in case , the import is less, and low kurtosis shows the relatively flat probability distribution. similarly, the kurtosis of the storage is high because the solar energy is low in the early daytime, at peak during midday, and reduces again during the later hours, generating a narrow probability distribution with a high kurtosis value. during the early hours, most of the energy (available) is used to increase the storage, and the remaining is exported to the grid. similarly, the import of energy is required only in the case of low storage resulting in the relatively flat probability distribution of export and import. table . statistical parameters of cases , , and . case skewness kurtosis import export storage import export storage − . na na . na na − . − . na . na − . − . − . . . . electronics , , of it is pertinent to mention that one of the important issue that could rise while implementing the approach is the capital cost. as we have proposed a dual battery system, it will burden a certain increase in the one-time capital cost, but is fruitful as the uninterrupted supply is provided at the low cost in addition to net profit and contrast with the conventional approaches. . conclusions solar energy is considered to be an entirely clean and favorable technology that can be used as an autonomous power source for various off-grid applications, to mitigate the energy crisis. in this work, an optimization model for the hybrid dual battery storage system with solar pv was presented. the proposed system operated optimally by charging the one battery and discharging the other, and a mathematical cost function of the system was devised. real data of the irradiance and load profile was collected from the consumers, and the influence of the two storage systems on the demand was evaluated. the proposed algorithm allowed the maximum usage of battery power during the peak hours and examined the cost analysis of all the three cases. the proposed dual battery with the solar pv system resulted not only in an uninterrupted supply, but also resulted in a good profit margin. the consequences of the comprehensive analysis of the proposed scheme over the conventional schemes, i.e., without the use of pv or the storage system, resulted in net savings, in addition to satisfying energy demands. the statistical analysis of import and export of power, and the energy storage presented in this study, favor the proposed methodology. author contributions: conceptualization, s.h.n., m.a.k., m.u.a. and h.j.k.; data curation, s.h.n. and m.-s.k.; investigation, s.h.n. and d.-h.k.; methodology, s.h.n., m.a.k. and m.u.a.; software, m.a.k., m.u.a. and m.-s.k.; supervision, h.j.k.; visualization, d.-h.k.; writing—original draft, s.h.n.; writing—review & editing, s.h.n. and a.h. funding: this research received internal funding from -year research grant of pusan national university. acknowledgments: this work was supported by a -year research grant of pusan national university. conflicts of interest: the authors declare no conflict of interest. references . mobil, e. the outlook for energy: a view to . exxon mobil , . 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[crossref] © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . /j.ijpe. . . http://dx.doi.org/ . /s - - -y http://dx.doi.org/ . /j.tej. . . http://www.solar.sheffield.ac.uk/s.s.n.d http://dx.doi.org/ . /ip-gtd: http://dx.doi.org/ . /j.egypro. . . http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	introduction 	energy spread and photovoltaic technology/pv energy and world demand 	energy storage and its effective utilization 	batteries and feed-in-tariff incentives/effective cost, and the impact of the pv system 	material and methods 	problem formulation 	methodological detail 	tariff details 	the time-of-use tariff 	export tariff 	import tariff 	results and discussion 	case 	case 	case 	conclusions 	references ippolito et al. bmc physiology ( ) : doi . /s - - - research article open access alteration in circulating metabolites during and after heat stress in the conscious rat: potential biomarkers of exposure and organ-specific injury danielle l ippolito , john a lewis , chenggang yu , lisa r leon and jonathan d stallings * abstract background: heat illness is a debilitating and potentially life-threatening condition. limited data are available to identify individuals with heat illness at greatest risk for organ damage. we recently described the transcriptomic and proteomic responses to heat injury and recovery in multiple organs in an in vivo model of conscious rats heated to a maximum core temperature of . °c (tc,max). in this study, we examined changes in plasma metabolic networks at tc,max, , or hours after the heat stress stimulus. results: circulating metabolites were identified by gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry. bioinformatics analysis of the metabolomic data corroborated proteomics and transcriptomics data in the tissue at the pathway level, supporting modulations in metabolic networks including cell death or catabolism (pyrimidine and purine degradation, acetylation, sulfation, redox alterations and glutathione metabolism, and the urea cycle/creatinine metabolism), energetics (stasis in glycolysis and tricarboxylic acid cycle, β-oxidation), cholesterol and nitric oxide metabolism, and bile acids. hierarchical clustering identified biochemicals that differentiated animals with histopathological evidence of cardiac injury at hours from uninjured animals. the metabolic networks perturbed in the plasma corroborated the tissue proteomics and transcriptomics pathway data, supporting a model of irreversible cell death and decrements in energetics as key indicators of cardiac damage in response to heat stress. conclusions: integrating plasma metabolomics with tissue proteomics and transcriptomics supports a diagnostic approach to assessing individual susceptibility to organ injury and predicting recovery after heat stress. keywords: heat stress, metabolomics, systems biology, energetics, metabolic networks background heat illness and heat stroke, the most severe form of heat illness, are life-threatening conditions characterized by elevations in core temperature (tc) resulting from an inability to adequately dissipate excess body heat to the environment. the intrinsic nature of military operations (i.e., heavy physical activity in extreme environments) places military personnel at greater risk of developing heat-related illnesses. sustained military operations in the middle east have been accompanied by an increase in the number of heat stroke cases on the battlefield and * correspondence: jonathan.d.stallings.mil@mail.mil the united states army center for environmental health research, environmental health program, bldg. doughten drive, fort detrick, frederick, md - , usa full list of author information is available at the end of the article © ippolito et al.; licensee biomed centra commons attribution license (http://creativec reproduction in any medium, provided the or dedication waiver (http://creativecommons.or unless otherwise stated. in training. during the past two decades alone the inci- dence of heat stroke has increased over seven-fold [ ]. moreover, the -year mortality rates from heart, kidney, and liver failure in us forces increases by % in indi- viduals with a history of heat stroke [ , ]. in , us forces sustained over heat-related injuries requiring hospitalization, including cases of heat stroke [ ]. the actual incidence is projected to be considerably higher when considering undocumented instances that never reach triage [ , ]. in a five-year retrospective study, , cases of heat injury required medical resources to treat, including cases of heat stroke [ ]. the estimated cost to the military approaches $ million per year (usd), assuming a cost of $ per l. this is an open access article distributed under the terms of the creative ommons.org/licenses/by/ . ), which permits unrestricted use, distribution, and iginal work is properly credited. the creative commons public domain g/publicdomain/zero/ . /) applies to the data made available in this article, mailto:jonathan.d.stallings.mil@mail.mil http://creativecommons.org/licenses/by/ . http://creativecommons.org/publicdomain/zero/ . / ippolito et al. bmc physiology ( ) : page of day, an average hospital stay of . days, and cases of heat injuries and heat stroke per year [ ]. other costs include duty days and salary lost during recovery (up to . months) and the loss in investment and training associated with service discharge for medical reasons [ ]. taken together, these statistics indicate that there is an urgent need for earlier indicators of organ injury and susceptibility and molecular based indicators to improve return to duty decisions [ ]. the physiological responses to an excess heat load include elevations in heart rate, a drop in mean arterial pressure, attenuated sweating rates, stupor, and collapse. the molecular level alterations and influence of the physiological events preceding and contributing to the systemic inflammatory response associated with heat stroke remain largely unknown. heat stroke compro- mises tight junction integrity in the gut, resulting in leakage of bacteria into the circulation [ ]. if uncon- trolled, the ensuing thermoregulatory and immune re- sponses can progress to system inflammatory response syndrome (sirs) and ultimately multi-organ failure and death [ - ]. designing novel and effective treatment and detection strategies for heat stroke requires a better understanding of the physiological and molecular alter- ations that accompany heat stroke and characterize the sirs event. however, in human studies . – . °c is the highest ethically attainable maximal core temperature (tc,max), but these temperatures are insufficient to induce heat stroke. to overcome these ethical limitations, we re- cently described conscious rat and mouse models of heat illness [ , , - ]. the models use abdominally im- planted radiotelemetry units to track tc while supporting physiological and behavioral adjustments to heat stress. in a recent study, we used our physiological model of heat stress to conduct an integrated systems biology evaluation of transcriptomic and proteomic changes in heart, liver, kidney, and lung after heat stress, heat injury, and recov- ery [ ]. we identified discriminatory gene and protein signatures in heat-injured cardiac tissue reflecting pertur- bations in oxidative phosphorylation, energy production, and inflammatory response. these global changes in metabolic networks associated with energy production in target tissues suggest that more accessible biofluids (e.g., serum, plasma, urine, and saliva) are also likely to reflect changes in the physio- logical state of the heat-stressed and heat-injured organ- ism. metabolomic profiling of plasma in conjunction with proteomic and transcriptomic analysis has recently emerged as a powerful predictive tool reflecting the dy- namic responses to genetic modification and physiological, pathophysioloigcal, and/or developmental stimuli. how- ever, perturbation in metabolic networks has not been well studied in heat illness. understanding the metabolic response to heat illness and subsequent organ injury provides unique insight into understanding how mamma- lian systems react to heat illness and recovery. further, methods to interrogate metabolites in accessible biofluids have been developed to allow a global assessment of organism response to environmental stressors [ ]. one disadvantage of metabolomics is the likelihood of false positives given the metabolome’s exquisite sensitivity to subtle changes in physiology (e.g., food intake, changes in temperature, stress, etc.). therefore, any study of the metabolome must discriminate pathological changes in metabolic networks from changes inherent in normal physiological functioning. integrating metabolic networks at the level of molecular function is one approach to dif- ferentiate changes related to heat-stress and/or heat-injury from physiological variation in the unperturbed system. bioinformatics methods can be used to identify an inte- grated panel of multiple physiological networks and biomarkers. in this study, we evaluate the metabolomic profile in response to heat stress and heat injury, and compare the results with the proteomic and transcriptomic profiles described previously. we demonstrate plasma metabolo- mics profiles unique to the physiological conditions of heat stress, heat injury in cardiac tissue, and heat stress without injury. metabolomics network analysis demon- strates perturbations in biological processes associated with energy usage and cell death, similar to the transcripto- mics and proteomics analyses conducted previously. fur- ther, integrated analysis of variance (anova) analysis, random forest analysis, and hierarchical clustering analysis identify panels of biochemicals differentiating controls from heat-stressed and heat-injured animals. results and discussion thermoregulation and histopathology tc,max was reached at – hours, as previously published by our laboratories in more detailed thermoregulation analyses conducted with these animals and other similar studies [ , ]. animals in the and hour cohorts were allowed to recover for the specified time prior to termination. in thermoregulation studies with these ani- mals, temperatures return to baseline by – hours, but cardiac-injured animals exhibit hypothermia before recovery, as published in detail by our laboratory [ ]. liver, kidney, and heart were assessed by histopath- ology and scored for evidence of injury as described pre- viously [ ]. the heart was the only tissue with treatment- related evidence for injury, with inflammation and cardio- myopathy in three out of six animals in the heated cohort as described in detail in a recent publication from our laboratory [ ] (additional file a). for the remainder of the study, animals in the hour treatment group were sub-stratified into cohorts according to uninjured vs. injured. ippolito et al. bmc physiology ( ) : page of the metabolomics heat stress response and recovery in plasma—biochemical networks overview of metabolic network changes a total of biochemicals were identified that matched named/identified chemicals in metabolon’s reference library, with unidentified biochemicals (additional file ). the largest change in number of biochemicals relative to controls occurred at tc,max, with fewer alter- ations at and hours. the key biochemicals repre- sented pathways related to the following categories: cell death or catabolism (pyrimidine and purine degradation, acetylation, sulfation, redox alterations and glutathione metabolism, and the urea cycle/creatinine metabolism), energetics (stasis in glycolysis and tricarboxylic acid [tca] cycle, β-oxidation), cholesterol and nitric oxide metabolism, and bile acids (figure ). tc,max showed the greatest percentage of biochemicals altered in response to heat injury in virtually all categor- ies. at tc,max, nearly % of identified biochemicals associated with cell death in a given pathway were elevated, suggesting an overall increase in biosynthesis to combat an overt exposure to redox stress (figure ). figure altered metabolic pathways and process networks in plasm super-pathway and sub-pathway. pathways meeting significance threshold identified in the plasma (at right). significance thresholds were determined hour endpoint was further subdivided into injured or uninjured animals biochemicals in all enriched metabolic pathways relating to cell death were up-regulated at tc,max, with progres- sively fewer biochemicals within each pathway elevated and/or reverting to down-regulation over time (figure ). in a two-way anova with contrasts evaluating changes across all time points, seven key biomarkers demarcated heat stress from control during recovery: , -dihydroura- cil, -ureidopropionate, gssg, ornithine, creatinine, cor- ticosterone and pyridoxal (table ). redox stress and cell death the glutathione (gsh) metabolic network exhibited pro- found perturbation in response to heat stress (figure ). all three biochemicals involved in glutathione metabolism were elevated at tc,max, probably as a result of heat- initiated redox crisis (figure ). γ-glutamylated amino acids (including alanine, glutamine, isoleucine, leucine, phenylalanine, tyrosine, and valine [additional file ]), -oxoproline, cysteine-gsh disulfide, and glutamate were significantly greater than control levels at tc,max. γ- glutamylmethionine was slightly elevated at tc,max, but the difference did not reach statistical significance a of rats after heat stress. biochemicals were grouped by kegg s were plotted by number of affected metabolites per total number by anova, by ratio of heat/control at tc,max, or hours. the by cardiac histopathology. table list of seven key biochemical differentially expressed in heat-stressed and control animals* identified biochemical (pathway) literature review (biochemical and/or pathway) references , -dihydrouracil (pyrimidine metabolism) early signal of apoptosis; dna damage from reactive oxygen species elevation; deficiency [ - ] -ureidopropionate (alanine/ aspartate metabolism) increased reactive oxygen species; inhibition of mitochondrial energy metabolism; neurotoxic/ excitotoxic [ ] ornithine (urea cycle, arginine metabolism) production of arginine and increase in autophagy, cell death, removal of excess nh +, energy metabolism; slight renal dysfunction [ ] glutathione disulfide, oxidized (redox) apoptosis, dna damage, cell proliferation, survival, differentiation, metabolism; redox stress and/ or crisis due to elevated reactive oxygen species [ - ] corticosterone (steroid/sterol metabolism) mitochondrial conversion of acetyl-coa to cholesterol and conversion of cholesterol to corticosterone; adrenal cortex production of cholesterol to pregnenalone, and ultimately cortisol; involved in glucocorticoid activity and stress response [ ] -α-hydroxy- -oxo- -cholestenoate [ -hoca] (steroid/sterol metabolism) bile acid synthesis from cholesterol; cyp a activity in the liver; bile acid synthesis [ ] pyridoxal (vitamin b metabolism) decreased renal function; anabolism; cofactor for reaction releasing glucose from glycogen [ ] *not segregated based on cardiac injury. ippolito et al. bmc physiology ( ) : page of (additional file ). at and hours, gssg remained el- evated. at hours, three of the biochemicals in gsh redox regulation remained elevated (γ-glutamylphenylala- nine, -oxoproline, and oxidized glutathione [gssg]). production of reactive oxygen species (ros) and oxi- dative stress occur when the cell’s protective mecha- nisms are saturated. ros also play key signaling roles in cell proliferation, survival, disease and pathophysiology [ ]. increased ros may lead to apoptosis, dna dam- age, cell proliferation, survival, differentiation, and dis- ruption in metabolism [ ]. heat exposure elevates free figure initial elevation in glutathione metabolism with recovery by disposition after recovery (fold-change, heat/control). (b) the glutathione m after heat exposure. *p < . heat exposed versus control rat, two-way an ggt, γ-glutamyl transferase; gs, glutathione synthase. radicals [ ]. free radicals and other ros are neutral- ized by gsh in redox regulation cycles. deficient and/or dysfunctional gsh can disrupt cell processes and lead to cell death [ ]. oxidized gsh can be reduced back by glutathione reductase with nadph (nicotinamide aden- ine dinucleotide phosphate) as an electron donor. gsh donates a reducing equivalent to unstable redox species. under normal physiological conditions, more than % of the glutathione pool is in the gsh form and less than % is in the disulfide gssg form. the ratio of gsh to gssg is a metric of cellular toxicity, with elevated gssg – hours. (a) biochemicals altered in heat exposure and etabolic pathway. circled biochemicals represent changes observed ova with contrasts. aa, amino acid; gcs, γ-glutamyl cysteine synthase; ippolito et al. bmc physiology ( ) : page of indicating oxidative stress [ ]. taken together, these results suggest that early perturbations in metabolic net- works elicit persistent redox stress out to hours after exposure. these persistent metabolic changes in heat- stressed individuals may affect performance during sub- sequent episodes of heat injury. arginine metabolism, nitric oxide metabolism, and cell death six biochemicals involved in arginine metabolism were altered after heat exposure (figure ). these biochemi- cals were involved in the urea cycle, which feeds creatine- to-creatinine production during metabolic mobilization of the muscle and/or brain energy reserves during energy crisis. heat stress increased citrulline, decreased arginine, and increased urea in rat plasma at tc,max (figure a). trans- -hydroxyproline was not significantly changed in concentration after heat stress (additional file ). elevated citrulline levels suggest a concomitant in- crease in nitric oxide, a product of inflammatory signal- ing (figure b) [ ]. increased urea may be associated with cell death, autophagy, and/or protein degradation. the combination of elevated urea and creatinine could also suggest renal dysfunction, consistent with the pro- teinosis observed in the renal histopathology as reported in the companion study. elevated plasma creatinine at later time points could indicate continued use of skeletal muscle energy reserves and persistent renal dysfunction. concomitantly decreased arginine and increased urea figure alterations in arginine metabolism and the urea cycle after biochemicals as a function of time after heat exposure (fold-change, heat/c cycle, and energy metabolism. *p < . heat exposed versus control rat, tw may indicate slower kinetics of arginine metabolism with increased urea production (figure b). increased urea may also be the result of an increase in nh +, a bypro- duct of cellular death [ ]. at and hours, citrulline levels were no longer elevated, suggesting that nitric oxide (no) production had decreased. interestingly, however, ornithine levels increased at and hours, possibly reflecting slower ar- ginine metabolism kinetics in general [ ]. taken together, these data suggest that a slight renal dysfunction was maintained during recovery, consistent with histopatho- logic evidence suggesting renal dysfunction. purine/pyrimidine metabolism and cell death fourteen out of identified biochemicals in the pyrimi- dine and purine metabolic pathways were significantly dif- ferent at tc,max relative to control (figure and additional file ). exceptions were adenosine monophosphate (amp), uridine, cytosine, and dihydroorotate. uracil, , -dihy- drouracil, -ureidopropionate, β-alanine, and an acetylated form of β-alanine, n-acetyl-β-alanine, were all significantly increased at tc,max compared to control rats, suggesting that a significant proportion of biochemicals involved in pyrimidine degradation was altered (additional file ). significantly, nearly all the biochemicals immediately up- stream of β-alanine metabolism in the pyrimidine metabol- ism reference kyoto encyclopedia of genes and genomes (kegg) pathway are modulated, suggesting that a signifi- cant proportion of this biochemical network is affected by heat exposure. (a) change in plasma arginine metabolism ontrol). (b) biochemical pathway of inflammation signaling, the urea o-way anova with contrasts. ippolito et al. bmc physiology ( ) : page of heat stress at tc,max. in plant cells, alterations in pyrimidine nucleotide metabolism are considered an early signal of apoptosis and often are induced by an increase in en- dogenous no [ ]. -ureidopropionate, the substrate of the enzyme dihydropyrimidinase, was elevated (additional file ) while the product, , -dihydrouracil, was decreased (additional file ), suggesting a down-regulation in the level of dihydropyriminidase activity or -ureidopropionate. further, carnosine is synthesized from l-histidine and β- alanine, with β-alanine as the rate-limiting precursor [ ], and -ureidopropionate as the precursor to β-alanine pro- duction. the result of these alterations in pyrimidine deg- radation could suggest dna damage by endogenous ros over-riding cellular repair and protection mechanisms. sev- eral altered biochemical pathways support elevated ros. acetylation or sulfation and cell death of the n-acetylated biochemicals detected, of compounds were significantly elevated at tc,max (additional file ). while of biochemicals were significantly chan- ged at hours, remained altered at hours. heat exposure appeared to change in the activity of acetyltrans- ferases or deacetylases, consistent with cellular damage. this initial response probably reflects hypoxia and initiation of cell death [ ]. acetyltransferases and deacetylases may allow an organism to adapt to recovery. eight sulfated compounds were detected and at tc,max, of which seven were significantly increased (additional file ). in addition, seven unnamed, putatively sulfated compounds also increased at tc,max (x- , x- , x- , x- , x- and x- ; additional file ). at hours, all biochemicals which had been higher than con- trol at tc,max were now significantly lower than controls, with a reversal of the trend after hours (i.e., higher than controls; additional file ). sulfotransferase enzymatic activity may have been induced or the activities of sulfa- tases may have reduced initially to facilitate clearance of cellular debris [ ], then returned to control levels after recovery. amino acids and cell death of the identified amino acids, seven were decreased and eight were increased relative to controls at tc,max, with a trend toward overall down-regulation at hours and hours. the exception was lysine, with a trend to- ward an increase at tc,max, with elevations at both and hours (additional file ). at tc,max, serine, threo- nine and alanine were lower than control. all three amino acids are synthesized from glycolytic intermedi- ates. although not definitive, these results may suggest a decrease in glycolysis [ ]. moreover, glutamate, which is consumed in the production of these amino acids, was increased at tc,max. whether these amino acid changes are indicative of energetic alterations or increased autophagy is unclear [ ]. however, it is interesting to note that, at tc,max, amino acids used as anaplerotic contributors to the tca cycle (i.e., glutamate and the branched-chain amino acids leucine, isoleucine, and valine) were increased and amino acids potentially synthesized as a consequence of glycolysis were decreased (serine, alanine, and threonine) (additional file ). these results may indicate pertur- bations in glycolysis and an overall slowing of energy production. tca cycle intermediates and energetics all five of the tca cycle intermediates identified at tc, max were higher than controls (figure ), suggesting mitochondrial dysfunction and energy crisis. the con- comitant increase in -hydroxybutyrate (ahb) further supported a perturbation in mitochondrial function [ ]. by – hours, tca metabolites in the plasma were no longer significantly elevated, suggesting restoration of the tca cycle to homeostasis. β-oxidation, cholesterol synthesis, and bile acids -hydroxybutyrate (bhba) and carnitines were signifi- cantly increased at tc,max (additional file ), supporting an increase in fatty acid β-oxidation for energy produc- tion. increased β-oxidation is also implied from a trend toward lower plasma levels of the medium-chain fatty acids (e.g., palmitoylcarnitine, stearoylcarnitine, and oleoylcarnitine) relative to controls. these fatty acids can enter the mitochondria without requiring trans- porter activity (additional file ). further, hexanoylcarni- tine, a long-chain fatty acid conjugated to carnitine to facilitate entry into the mitochondria [ ], is increased in heated animals. increased β-oxidation may increase levels of acetyl coenzyme a (acetyl coa) (additional file , additional file a), but the profound down-regulation in glycolysis, tca cycle, and amino acid metabolism suggests that the acetyl coa is not being used for adenosine triphosphate (atp) production at tc,max. β-oxidation may also be up-regulated to facilitate chol- esterol synthesis and corticosterone production [ ]. at tc,max, corticosterone was significantly increased in heated animals relative to controls, and the increase persisted to – hours (additional file ). the increase in bhba may reflect an increase in acetyl coa for subsequent chol- esterol metabolism and steroidogenesis, but functional mitochondria are required for this process. alternatively, the elevated corticosterone could be released from the adrenal cortex during heat stress as part of a generalized stress response. studies suggest prophylactic treatment with glucocorticoids protects against heat stress [ ]. changes in corticosterone levels could gauge severity of perturbations during heat and recovery [ ]. bile acids and steroids are generated from cholesterol. following heat stress, plasma levels of steroids increased figure mitochondrial dysfunction suggested by elevated tca cycle intermediates and -hydroxybutyrate (ahb) at tc,max. (a) fold-change from control in biochemicals implicated in the tca cycle. (b) the tca cycle, with red circles indicating biochemicals with significant deviation from control after heat stress. *p < . heat exposed versus control rat, two-way anova with contrasts. ippolito et al. bmc physiology ( ) : page of with a concomitant decrease in bile acids, suggesting de novo steroidogenesis (additional file ). bile acid con- centration is usually low in the normal systemic circula- tion. with heat stress, levels of nearly all bile acids detected were even lower at tc,max (additional file ), possibly due to decreased reuptake within the small intestine and constricted intestinal circulation [ ]. co-factor metabolism in addition to the broad categories of energetics and cell death, metabolites of vitamin b are altered by heat stress (additional file ). heat stress resulted in an accu- mulation of pyridoxate (a breakdown product secreted in the urine), potentially reflecting renal dysfunction. pyridoxal levels were increased in heated animals rela- tive to controls at tc,max, possibly due to increased ca- tabolism. in contrast, pyridoxal and pyridoxate levels were lower than control at – hours, possibly due to increased anabolism (a process that requires b as a cofactor) and return to homeostasis (additional file ). data integration—random forest analysis to identify biochemicals which discriminate heat exposure from unheated controls taken together, the results of the metabolic pathway ana- lysis supports a model of heat stress perturbing metabolic networks affecting cell death and energetics. ultimately, these metabolic network perturbations lead to disruption of cholesterol and bile acid synthesis, nitric oxide produc- tion and inflammatory signaling, and vitamin b cofactor regulation (figure ). performing integrated anova ana- lysis across biochemicals at all time points identified seven biomarkers within five metabolic networks which discrim- inated heat stressed individuals from controls at any time point (figure ). figure model of heat stress and recovery and potential biomarkers. hierarchical clustering was used to compare heated and control animals hours after heat exposure. data clustered by cardioinflammation score in animals with the greatest histopathological evidence of injury. figure random forest analysis accurately discriminates heat exposure from unheated controls at tc,max. the top metabolites were identified in out-of-bag (oob) selection to have % predictive power by random forest analysis at tc,max. the inset represents predictive power of the biochemicals identified. colored circles indicate biochemicals that were also significantly up (red) or down (green) regulated, p < . , -way anova with contrasts. biochemicals marked by an asterisk indicate likely identifications based on ms/ms fragmentation and other chemical properties. ippolito et al. bmc physiology ( ) : page of ippolito et al. bmc physiology ( ) : page of random forest statistical analyses were used to deter- mine sets of biomarkers capable of discriminating control from heat stress at tc,max (figure ), hours (figure ) and hours (figure ) after exposure to heat. the out-of-bag (oob) error rate for each forest plot was %, . %, and %, respectively. the top predictive chemicals at tc,max were γ-glutamylvaline and allantoin (figure ). allantoin is not typically found in humans, but γ- glutamylvaline is elevated in response to perturbations in the redox cycle [ ] (see also figure ). at hours, the top predictive chemicals were c-glycosyltryptophan, n- acetyl-β-alanine, and asparagine (figure ). the predictive power of the model was slightly lower than tc,max, but still predicted with nearly % accuracy. at hours, the most predictive biochemicals were -methyl- ’deoxycytidine, pyridoxate, -methylhistidine, palmitoylcarnitine (c ), erythritol, -( -hydroxphenyl) lactate (hpla), pseudo- uridine, oleoylcarnitine (c ), and x- (figure ). figure random forest analysis accurately discriminates heat exposu were identified in oob selection to have % predictive power by random biochemicals identified. colored circles indicate biochemicals that were anova with contrasts. one biochemical was not significantly altered by an likely identifications based on ms/ms fragmentation and other chemical pr the degradation product of dna ( -methyl- ’-deoxycyti- dine) and pseudouridine (a representative of rna degrad- ation) are both likely representative of continued cell death (see also additional file ) [ ]. identification of predictive indicators of persistent cardiac injury at hours at hours, three out of six heated animals showed histopathological evidence of cardiac injury (see com- panion study). segregating injured from uninjured ani- mals did not result in significant differences at hours for any biochemical pathway grouping except acetylation and sulfation (additional files , , and ). using hier- archical clustering at hours, we evaluated the global change in metabolites after heat exposure, segregating the hour animals into injured and uninjured cohorts (n = per cohort). a panel of biochemicals discrimi- nated animals with histopathologic evidence of heart re from unheated controls at hours. the top metabolites forest analysis at tc,max. the inset represents predictive power of the also significantly up (red) or down (green) regulated, p < . , -way ova analysis (yellow). biochemicals marked by an asterisk indicate operties. figure random forest analysis accurately discriminates heat exposure from unheated controls at hours. the top metabolites were identified in oob selection to have % predictive power by random forest analysis at hours. the inset represents the top-scoring molecule ( -methyl- ’deoxycytidne). colored circles indicate biochemicals that were also significantly up (red) or down (green) regulated, p < . , -way anova with contrasts. one biochemical was not significantly altered by anova analysis (yellow). biochemicals marked by an asterisk indicate likely identifications based on ms/ms fragmentation and other chemical properties. ippolito et al. bmc physiology ( ) : page of injury from controls and uninjured, heated animals (figure ). biochemicals in the panel were sub-categorized by metabolic pathway (table ). ornithine and n - methyladenosine and taurodeoxycholate have been associ- ated with cardiac injury (summarized in table ). the results of the random forest analyses at each time point were most concordant with the two-way anova analysis at hours (two of the seven biomarkers identi- fied in both analyses— -hoca and corticosterone). at tc,max, only corticosterone was common to both ana- lyses, and at hours, only pyroxidate was common to both analyses. it is important to note, however, that of the biochemicals that were excellent classifiers of exposure were also significantly altered according to the anova analyses (as indicated by the red and green cir- cles in figures , , ). thus, rather than the manual and somewhat arbitrary selection of the top seven biochemical based on circulating levels, the random forest analysis pulls out a list of chemicals that in combination (whether up- or down-regulated) provide greater discriminatory power than a single biomarker, which may be a more powerful approach in populations that demonstrate sig- nificant individual variability in the metabolic response across time points. comparison of metabolic networks enriched in heat injury with complementary proteomics and transcriptomics pathway analysis the strength of metabolomics is in its analysis of hun- dreds of analytes simultaneously. multiple small changes (< -fold) within a given biochemical pathway can signal a physiologically relevant perturbation of a physiological network regulating a metabolic function [ ]. these physiologically relevant changes may be overlooked in figure metabolites discriminate animals with histopathologic evidence of heart injury versus uninjured animals at hours. hierarchical clustering was used to compare heated and control animals hours after heat exposure. data clustered by cardioinflammation score in animals with the greatest histopathological evidence of injury. ippolito et al. bmc physiology ( ) : page of the analysis of single analytes. the network-wide com- parison of plasma metabolites complements the tran- scriptomic and proteomic profiles observed in cardiac tissue in our recently published study [ ]. the greatest concordance was observed in down-regulated biomole- cules among kegg pathways enriched in the three data sets (figure ). metabolomics, proteomics, and tran- scriptomics data integration suggests concurrence in the transcripts, proteins, and metabolites supporting a down- regulation of oxidative phosphorylation and the tca cycle. taken together, these results support energy crisis and oxidative stress at hours in cardiac-injured animals. importantly, the metabolomics data obtained in plasma are concordant with tissue-based proteomics and tran- scriptomics profiles at the pathway level. sampling blood (an accessible biofluid) indicates cardiac distress at the tis- sue level in this study. the metabolomics data were more discordant than the proteomics and the transcriptomics data, especially when comparing up-regulated genes and proteins with metabolites in the corresponding kegg table review of metabolites differentiating animals with histopathological evidence of cardioinflammation from uninjured animals identified biochemical (pathway) literature review (biochemical and/or pathway) references ornithine (phenylalanine and tyrosine metabolism) inhibition of nitric oxide; relationship between nitric oxide modulation of the frank- starling response in heart; nitric oxide and nitric oxide synthase are sensitive to thermal stress in fish [ ] -( -hydroxyphenyl) propionate (phenylalanine and tyrosine metabolism) biological nitrification inhibition (in plants); phenylalanine and tyrosine concentrations are reduced after hsp increase and heat stress (in yeast) [ , ] n -methyladenosine (purine metabolism, adenine containing) n -methyladenosine analogues are cardioprotective agents in ischemic reperfusion model; decreased infarction; purine metabolism associated with myocardial steatosis and down-regulation of adipose triglyceride in heart [ , ] xylonate (nucleotide sugars, pentose metabolism) deficiency in pentose metabolism produces a protective effect through decreased cholesterol synthesis, superoxide production, and reductive stress [ ] -stearoylglycerol ( -monostearin) (monoacylglycerol) associated with increased lipid catabolism and remodeling mitochondrial oxidation to aerobic glycolysis (hepatocellular carcinoma) [ ] carnitine (carnitine metabolism) disrupted carnitine metabolism is associated with mitochondrial dysfunction and increased pulmonary flow (lamb model); cardioprotective by increasing heat shock protein synthesis in adriamycin-induced cardiomyopathy [ - ] taurodeoxycholate (bile acid metabolism) bile acids exert a protective effect after ischemic injury in porcine hearts; cause endoplasmic reticulum mitochondrial stress; deoxycholate and taurodeoxycholate affect heart mitochondria by decreasing respiration, affecting membrane potential, inducing mitochondrial permeability transition, and altering mitochondrial bioenergetics; impaired cardiac mitochondrial function may cause cardiac alterations in cholestasis [ - ] deoxycholate (bile acid metabolism) (see above) (see above) trigonelline (n’-methylnicotinate) (nicotinate and nicotinamide metabolism) cardioprotective effects after isoproterenol induced myocardial dysfunction (reduction in hsp , αb-crystallin and calcium/calmodulin dependent kinase-ii-δ) [ ] diisopropanolamine (xenobiotics - chemical metabolism) increases choline uptake without affecting phospholipid synthesis (chinese hamster ovary cells) [ ] x – (unknown) n/a n/a x – (unknown) n/a n/a x – (unknown) n/a n/a x – (unknown) n/a n/a x – (unknown) n/a n/a ippolito et al. bmc physiology ( ) : page of pathways. however, amino acid/nucleotide sugar metabol- ism were modulated at the transcript, protein, and metab- olite level, supporting a stasis of energy production/energy crisis (figure ). combined with the panel of potential cardiac injury markers (figure ), these results suggest a plasma-based series of metabolic indicators for tissue damage induced by heat stress. detecting biomarkers pre- dictive of cardiac injury in an accessible biofluid supports further studies investigating whether these metabolites represent viable biomarker candidates for predicting cardiac injury and recovery. conclusion in this work, we present a plasma metabolomic profile of heat stress and heat injury in an in vivo rodent model of heat stress. the metabolomic profile in plasma is concord- ant with tissue proteomics and transcriptomic profiles in- dicating energy crisis and oxidative stress, suggesting that metabolic indicators in the plasma may provide surro- gate markers for tissue injury in an accessible biofluid. coupled with the earlier work in tissue transcriptomics and proteomics in the heat-stressed rodent model [ ], the global metabolomic profiles identified the basis for future work for modeling the response to heat stress and heat injury [ ]. integration of metabolomics, pro- teomics, and transcriptomics in a top-down manner will provide the foundation for network analysis and com- putational based experiments in a human d thermore- gulation model [ ]. anchoring these systemic stress responses to the physiological model of heat stroke will provide further insight into forecasting risk of disease, timing of disease onset, and intensity of disease at the organ level. as a result, we anticipate that such a model would accelerate the development of tools to improve dis- ease prevention, classification, and ultimately treatment. methods materials and methods animal model in vivo rat experiments were performed at the us army research institute of environmental medicine (usariem). the institutional animal care and use committee figure down-regulated biomarkers predictive of cardiac injury. kegg pathways negatively enriched in animals with cardiac injury were compared across transcriptomics, proteomics, and metabolomics studies in cardiac tissue. for metabolomics results, the metabolon pathway designation is listed along with the complementary kegg designation (in david). the metabolomics studies are described in this study and the proteomics and transcriptomics results were described in detail in a previous study. *, previous study; **, this study; red text, common to at least two data sets, with the same direction in all data sets (up-regulated or down-regulated); blue text, common to at least two data sets, but direction (up-regulated or down-regulated) differs. ippolito et al. bmc physiology ( ) : page of approved all experimental procedures, which were per- formed in accordance with the american physiological society’s guiding principles for research involving animals and adhered to the high standard (best practice) of veterin- ary care as stipulated in the guide for care and use of la- boratory animals. research was conducted in compliance with the animal welfare act, and other federal statutes and regulations relating to animals and experiments involv- ing animals and adheres to principles stated in the “guide for care and use of laboratory animals” (nrc ) as prepared by the committee on care and use of laboratory animals of the institute of laboratory animal resources, national research council in facilities that are fully accre- dited by the association for assessment and accreditation of laboratory animal care, international. as previously de- scribed [ ], male fischer (f ; n = ; charles river laboratories, stone ridge, ny) rats weighing – g (~ – months old) were used. briefly, rats were housed under standard laboratory conditions ( °c, : hour light:dark cycle, lights on at : am) in an association for assessment and accreditation of laboratory animal care-accredited facility. a relatively cool housing temperature was chosen to support survival during heat-stress recovery [ ], during which chow (harlan teklad, lm- ; madison, wi) and water were pro- vided ad libitum [ ]. rats were implanted with tl m -c -pxt physiotel® multiplus transmitters (data sciences international, st. paul, mn) to measure core temperature (tc; ± . °c), heart rate, and mean arterial pressure (± mmhg). physiological response and temperature regulation after heat stress has been pub- lished in recent studies by our laboratories [ , , ]. all experiments were conducted in conscious, free- moving animals, as previously described [ ]. briefly, rats were placed in a floor-standing incubator (thermo scientific, ashville, nc) set at room temperature (rt, °c) hours prior to initiation of heat stress experi- ments. non-heated rats were not introduced to the incu- bator environment. heat-stress experimentation was initiated after tc of the control and experimental rats reached values of approximately . °c. the follo- wing day, food and water were removed from the animal figure up-regulated biomarkers predictive of cardiac injury. kegg pathways positively enriched in animals with cardiac injury were compared across transcriptomics, proteomics, and metabolomics studies in cardiac tissue. for metabolomics results, the metabolon pathway designation is listed along with the complementary kegg designation (in david). the metabolomics studies are described in this study and the proteomics and transcriptomics results were described in detail in a previous study. *, previous study; **, this study; red text, common to at least two data sets, with the same direction in all data sets (up-regulated or down-regulated); blue text, common to at least two data sets, but direction (up-regulated or down-regulated) differs. ippolito et al. bmc physiology ( ) : page of cages; the incubator temperature was increased to . ± . °c; and the rats were heated until a tc of . °c (tc,max) was reached, at which time they were removed from the incubator, weighed, placed in a new cage, and returned to normal housing temperature ( . ± . °c). animals in the and hour cohorts were allowed to recover for the specified time prior to termination. time-matched control rats experienced the same experimental procedures as the heat-stressed rats, but remained at the normal housing temperature of . °c throughout experimenta- tion. control and experimental animals were provided food and water ad libitum throughout recovery. plasma, heart, liver, lung, and kidney were harvested at tc,max, , or hours with tc, mean arterial pressure, and heart rate monitored continuously throughout recovery. histopathology at necropsy, tissues (heart, liver, lung, kidney) were fixed in paraformaldehyde, mounted, sectioned, and stained with hematoxylin and eosin (ihc world, woodstock, md). twenty serial sections were cut per tissue, with three to five sections per slide. inflammatory or degen- erative lesions were graded on a scale of to (grade , minimal; grade , severe) by a board-certified pathologist (experimental pathology laboratories® [sterling, va]). the results of the histopathological evaluation have been previously published [ ]. metabolomics metabolomic analysis was conducted by metabolon (durham, nc). briefly, frozen plasma samples ( μl) were thawed, and extracts were prepared according to metabolon’s standard protocol, which is designed to re- move protein, dislodge small molecules bound to protein or physically trapped in the precipitated protein matrix and recover a wide range of chemically diverse metabo- lites. samples were extracted and split into equal parts for analysis on the gas chromatography mass spectrometer and liquid chromatography mass spectrometer platforms. proprietary software was used to match ions to an in- house library of standards for metabolite identification and for metabolite quantitation by peak area integration. data analysis—metabolomics two-way anova with contrasts was used to analyze the data (see additional file ). for all analyses, missing values (if any) were inputted with the observed mini- mum for that particular compound (inputted values were added after block-normalization). the statistical analyses were performed on natural log-transformed ippolito et al. bmc physiology ( ) : page of data to reduce the effect of any potential outliers in the data. two-way anova and contrast comparisons were made between the means of each biochemical from the groups and were calculated using either or both of the statistical analysis software programs array studio (omicsoft, inc.) or ‘r’ (r foundation for statistical com- puting, vienna, austria). statistical cut-offs are typically used to detemine physiological significance in metabolo- mics studies. conservative criteria of p < . and q < . are routinely used in metabolomic studies [ ], allowing for the identification of significantly altered responses between groups with a false discovery rate of no more than %. because we analyzed a constellation of metab- olites in conjunction with biochemical pathways rather than single analytes, we considered p < . significant, regardless of the q value. using this approach, we could be more inclusive of data that did not meet strict cut-off values, taking both p-value and number of metabolites changing in a given biochemical pathway. random forest, a supervised classification technique based on an ensemble of decision trees [ , ] was used to determine the predictive value of multiple biochemi- cals for both exposure and health effect. for a given de- cision tree, a random subset of the data with identifying true class information was selected to build the tree (“bootstrap sample” or “training set”), and then the remaining data, the oob variables, were passed down the tree to obtain a class prediction for each sample, then repeated thousands of times to produce the forest. the final classification of each sample was determined by computing the class prediction frequency for the oob variables over the whole forest. class predictions were compared to the true classes, generating the “oob error rate” as a measure of prediction accuracy. to de- termine which variables (biochemicals) made the largest contribution to the classification, a variable importance measure was computed, termed the mean decrease ac- curacy (mda). the mda was determined by randomly permuting a variable, running the observed values through the trees, and then reassessing the prediction accuracy. if a variable is not important, then this procedure had little change in the accuracy of the class prediction (permuting random noise gave random noise). by contrast, if a vari- able is important to the classification, the prediction accuracy will drop after such a permutation, which we record as the mda. thus, the random forest analysis provided an importance rank-ordering of biochemical, and the top biochemicals were reported. additional files additional file : is the raw metabolomics data and anova with contrasts for each biochemical analyzed in the study. additional file : heat stress persistently increases metabolites controlling pyrimidine and purine degradation. (a) eighteen biochemicals were identified in the purine and pyrimidine metabolism sub-pathways: at tc,max, fold changes (heat/control) were significantly increased for biochemicals and significantly decreased for biochemical; at hours, biochemicals were increased and decreased; and at hours, were elevated and decreased in both uninjured and heat-injured animals. (b) biochemical pathway for pyrimidine degradation. red, increased over control; green, decreased relative to control; green and red, p < . ; light red, . < p < . . additional file : acute increase in acetylated biochemicals followed by a decrease at hours and significant differences between uninjured animals and animals with cardiac injury at hours. of the acetylated biochemicals at tc,max, were greater in heated animals than controls; at hours, were significantly lower and were significantly higher; at hours in uninjured animals, were significantly higher and were significantly lower; in heat-injured animals, were higher and were lower than controls. red, fold change significantly higher; green, fold change significantly lower than control (p < . by anova); light green, fold change lower compared to controls ( . < p < . by anova). additional file : acute increase in sulfated biochemicals followed by a decrease at hours and significant differences between uninjured animals and animals with cardiac injury at hours. of the sulfated biochemicals at tc,max, were greater in heated animals than controls; at hours, were significantly lower and none were significantly higher; at hours in uninjured animals, were significantly higher and none were significantly lower; and in heat-injured animals, were higher and none were lower than controls. red, fold change significantly higher; green, fold change significantly lower than control (p < . by anova); light green, fold change slightly lower compared to controls with . < p < . by anova. additional file : altered amino acids and mediators of glycolysis, gluconeogenesis, and pyruvate metabolism after heat stress and recovery. (a) of the identified amino acids, at tc,max were significantly lower and were significantly greater; were lower at hours; at hours, were lower and was greater in both uninjured and cardiac-injured animals. metabolites contributing to glycolysis were initially greater than control, then either returned to normal or were lower than control at and hours. red, fold change significantly higher; green, fold change significantly lower than control (p < . by anova); light green, fold change slightly lower compared to controls; light red, fold change lightly higher than control ( . < p < . by anova). (b) three amino acids that contribute to the tricarboxylic acid (tca) cycle for energy production were decreased. additional file : increased fatty acid β-oxidation modulates acetyl coa production and cholesterol synthesis in energy production. (a) metabolic network illustrating how elevations in fatty acid β-oxidation compensates for compromised tca cycle, glycolysis, and amino acid metabolism in the production of cellular energy. (b) alterations in medium chain fatty acids in response to heat stress and recovery. (c) alterations in biochemicals involved in carnitine metabolism after heat stress. green cells represent significant decrease. red cells represent a significant increase in heat-stressed individuals over control cases ( . < p < . heat exposed versus control rat, -way anova with contrasts). additional file : decrease in bile acids and increase in associated metabolites of bile acid biosynthesis at tc,max and – hours after heat exposure. (a) tabulation of bile acids and associated metabolites at tc,max and – hours as fold-change from control after heat exposure. (b) circulation of bile acids. (c) trend in bile acid and associated metabolites over time after heat stress. green cells represent significant decrease. pink reflects a trending increase and light green represents a trending decrease ( . < p < . heat exposed versus control rat, -way anova with contrasts); *, p < . , -way anova with contrasts. additional file : change in vitamin b cofactor activity at tc,max and – hours after heat exposure. (a) role of vitamin b metabolism in amino acid, serotonin/norepinephrine, and sphingolipid synthesis. trend in (b) pyridoxal and (c) pyridoxate after heat stress. *, p < . , -way anova with contrasts. http://www.biomedcentral.com/content/supplementary/s - - - -s .xlsx http://www.biomedcentral.com/content/supplementary/s - - - -s .pdf http://www.biomedcentral.com/content/supplementary/s - - - -s .pdf http://www.biomedcentral.com/content/supplementary/s - - - -s .pdf http://www.biomedcentral.com/content/supplementary/s - - - -s .pdf http://www.biomedcentral.com/content/supplementary/s - - - -s .pdf http://www.biomedcentral.com/content/supplementary/s - - - -s .pdf http://www.biomedcentral.com/content/supplementary/s - - - -s .pdf ippolito et al. bmc physiology ( ) : page of abbreviations -hoca: -α-hydroxy- -oxo- -cholestenoate; aa: amino acid; acetyl coa: acetyl coenzyme a; ahb: -hydroxybutyrate; amp: adenosine monophosphate; anova: analysis of variance; atp: adenosine triphosphate; gcs: γ-glutamyl cysteine synthase; ggt: γ -glutamyl transferase; gsh: glutathione; gs: glutathione synthase; gssg: glutathione disulfide, oxidized; kegg: kyoto encyclopedia of genes and genomes; mda: mean decrease accuracy; nadph: nicotinamide adenine dinucleotide phosphate; no: nitric oxide; oob: out-of-bag; ros: reactive oxygenated species; sirs: system inflammatory response syndrome; tc,max: maximum core temperature; tca: tricarboxylic acid; usacehr: us army center for environmental health research; usamrmc: us army medical research and materiel command; usariem: us army research institute of environmental medicine. competing interests the authors declare that they have no competing interests to declare. research was conducted in compliance with the animal welfare act, and other federal statutes and regulations relating to animals and experiments involving animals and adheres to principles stated in the “guide for care and use of laboratory animals” (nrc ) as prepared by the committee on care and use of laboratory animals of the institute of laboratory animal resources, national research council in facilities that are fully accredited by the association for assessment and accreditation of laboratory animal care, international. the views, opinions, assertions, and/or findings contained herein are those of the authors and should not be construed as official us department of defense or department of the army position, policy, or decision, unless so designated by other official documentation. citations of commercial organizations or trade names in this report do not constitute an official department of the army endorsement or approval of the products or services of these organizations. this paper has been approved for public release with unlimited distribution. this research was supported in part by an appointment to the research participation program at the us army center for environmental health research (usacehr) administered by the oak ridge institute for science and education through an interagency agreement between usacehr, the us department of energy, and the us army medical research and materiel command (usamrmc). the research was supported by the military operational medicine research program, usamrmc, md. authors’ contributions the initiation and conception of this study involved jds, jal, and lrl. cy and jal provided critical methods review, random forest analyses, hierarchical clustering. dli (overall) and jds were responsible for writing the manuscript, which was edited by cy, jal, and lrl. all authors reviewed the final manuscript. acknowledgements we would like to thank dr. roy vigneulle (military operational medicine research program), capt carroll d. forcino (director, military operational medicine research program), dr. david a. jackson (director, pulmonary health, usacehr), and ltc thomas c. timmes (current commander, usacehr) for their programmatic support, encouragement, and insightful discussion. we also thank dr. bryan helwig, j. ward, s. dineen, m. blaha, and r. duran for access to biofluids and technical support with the rat heat stress experiments. we thank dr. andrea eckhart and dr. rob mohney from metabolon, inc., for the report and data analysis of the metabolomics data. author details the united states army center for environmental health research, environmental health program, bldg. doughten drive, fort detrick, frederick, md - , usa. biotechnology high performance computing software applications institute, frederick, md - , usa. thermal mountain medicine division, us army research institute of environmental medicine, natick, ma - , usa. received: june accepted: december references . armed forces health surveillance c: update: heat injuries, active component, u.s. armed forces, . msmr , ( ): – . . wallace rf, kriebel d, punnett l, wegman dh, wenger cb, gardner jw, gonzalez rr: the effects of continuous hot weather training on risk of exertional heat illness. med sci sports exerc , ( ): – . . wallace rf, 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res , ( ): – . . bartel j, krumsiek j, theis fj: statistical methods for the analysis of high-throughput metabolomics data. comput struct biotechnol j , :e . . breiman l: using iterated bagging to debias regressions. mach learn , ( ): – . . goldstein ba, hubbard ae, cutler a, barcellos lf: an application of random forests to a genome-wide association dataset: methodological considerations & new findings. bmc genet , : . submit your next manuscript to biomed central and take full advantage of: • convenient online submission • thorough peer review • no space constraints or color figure charges • immediate publication on acceptance • inclusion in pubmed, cas, scopus and google scholar • research which is freely available for redistribution submit your manuscript at www.biomedcentral.com/submit 	abstract 	background 	results 	conclusions 	background 	results and discussion 	thermoregulation and histopathology 	the metabolomics heat stress response and recovery in plasma—biochemical networks 	overview of metabolic network changes 	redox stress and cell death 	arginine metabolism, nitric oxide metabolism, and cell death 	purine/pyrimidine metabolism and cell death 	acetylation or sulfation and cell death 	amino acids and cell death 	tca cycle intermediates and energetics 	β-oxidation, cholesterol synthesis, and bile acids 	co-factor metabolism 	data integration—random forest analysis to identify biochemicals which discriminate heat exposure from unheated controls 	identification of predictive indicators of persistent cardiac injury at  hours 	comparison of metabolic networks enriched in heat injury with complementary proteomics and transcriptomics pathway analysis 	conclusion 	methods 	materials and methods 	animal model 	histopathology 	metabolomics 	data analysis—metabolomics 	additional files 	abbreviations 	competing interests 	authors’ contributions 	acknowledgements 	author details 	references energy consumption and greenhouse gas emission from ceramic tableware production: a case study in lampang, thailand - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of aedcee doi: . /j.egypro. . . energy procedia ( ) – sciencedirect international conference on alternative energy in developing countries and emerging economies energy consumption and greenhouse gas emission from ceramic tableware production: a case study in lampang, thailand panatda riyakada, siriluk chiarakorna* adivision of environmental technology school of energy, environment and materials king mongkut’s university of technology thonburi, bangkok , thailand abstract this paper presents energy consumption and greenhouse gas (ghg) emission from ceramic tableware production in lampang, thailand. all data of energy consumption in ceramic production were collected from a small enterprise manufacturing plant and the unit of analysis was kg of product. a scope of study was gate to gate. the amount of ghg emission in a unit kgco e/kg of product was calculated by ipcc guidelines for national greenhouse gas inventories method and the emission factors were referred from thailand greenhouse gas management organization (tgo) and ipcc databases. the results showed that the total energy consumption from ceramic tableware production was . mj/kg of product and almost % of total energy consumption was from liquefied petroleum gas (lpg) consumption during firing. the amount of ghg emission was . kgco e/kg of product. the glost firing was found to be a hotspot of energy consumption and ghg emission. © the authors. published by elsevier ltd. peer-review under responsibility of the organizing committee of aedcee. keywords: energy consumption, greenhouse gas emission, ceramic tableware,ceramic production, lampang * corresponding author. tel.: + ; fax: + . e-mail address: siriluk.chi@kmutt.ac.th (s.chiarakorn). available online at www.sciencedirect.com © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of aedcee http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf panatda riyakad and siriluk chiarakorn / energy procedia ( ) – . introduction ceramic industry is one of the important industries of thailand. the revenues from ceramic industry has been increasing up to , million baht per year [ ]. main ceramic products consists of ceramic tiles, sanitary wares, gift and decorations, tablewares and insulators. among all products, tablewares ranked the most exported ceramic product, contributed for . % of total exported ceramic products in thailand, followed by sanitary ware ( . %) and ceramic tiles ( . %) [ ]. in thailand, there are approximately ceramic tableware producers but more than % are located in lampang, northern thailand [ ]. it is widely known that the most famous product, “cham tra kai” a ceramic tableware with a hen design, is the signature of lampang. but nowadays, lampang ceramic industry has suffered from energy crisis because the cost of energy has been continuously increasing. as a result, many small plants have been shut down. ceramic production are energy intensive because firing process requires the temperature ranged from – °c [ ]. ceramic production is not only one of industry that consumes high energy but also emits large amount of greenhouse gases (ghg) which cause global warming [ ]. however, the database of energy consumption as well as ghg emissions from ceramic tableware production have not been available. therefore, this research aimed to evaluate the energy consumption and ghg emission of ceramic tableware production from a small enterprise manufacturing plant in lampang, thailand. the hotspots of energy consumption and ghg emission were identified. the output results could be useful information for energy conservation and ghg management in ceramic tableware production. fig. . a stoneware plate ( -inch diameter) selected in this study . methodology the activities data were collected from a small enterprise manufacturing plant in lampang, thailand. the -inch stoneware (fig. ) was selected as an example in this study. the average weight of the plate was . kg/piece. the forming process was jiggering method. a jiggering machine was shown in fig . a scope of this study was gate to gate. the energy consumption and ghg emission in each manufacturing process were analysed, based on the functional unit of kg product. the amount of ghg emission was calculated by ipcc method. the emission factors were from tgo and ipcc databases as presented in table . the ghg emission in a unit of kgco e/kg of product was calculated by eq. ( ) [ ] and eq. ( ) [ ]. the eq. ( ) was used to calculate amount of ghg emission from energy consumption (electricity and lpg). the eq. ( ) was used to calculate amount of carbon dioxide emission from decomposition of caco . in this study, the calcination fraction (f) was unknown and the method from ipcc( ) recommended using f value as . for the calculation. panatda riyakad and siriluk chiarakorn / energy procedia ( ) – ( ) ef (unit) dataactivity emission ghg where ef = emission factor, kgco e/unit ( ) fefm caco ofion decomposit from emissions co caco where efcaco = emissions factor for the particular carbonate, tonnes co /tonne carbonate m = weight or mass of the carbonate, tonnes f = fraction calcination achieved for the carbonate, fraction fig. . a jiggering machine used in this study table . the emission factors used in this study activity data unit emission factor references liquefied petroleum gas (lpg) kg . kgco e/unit [ ] electricity kwh . kgco e/unit [ ] calcium carbonate (caco ) tonne carbonate . tonnes co / unit [ ] * tonne = kg . ceramic tableware production the production processes of stoneware plate was presented in fig. . the clay was purchased from clay manufacturer. then, the products were formed by jiggering method and dried at room temperature. after drying, the products were loaded on shuttle kiln for a first firing at °c for h, called biscuit firing. the next step was glazing, the products were covered with thin glaze layer. after that, the glazed plates were loaded into shuttle kiln for glost firing at , °c for h. both firing processes used lpg. finally, the final products were conveyed to the quality checking and classified the quality level as either grade a, grade b or another grades. panatda riyakad and siriluk chiarakorn / energy procedia ( ) – fig. . production process of a stoneware plate . results and discussion the total energy consumption of ceramic tableware production was . mj/kg of product, contributed by electricity only . % and lpg . %. the energy consumption and ghg emission from each process are shown in table . major energy sources consumed in ceramic tableware production were from electricity and lpg. the electricity consumption was only from forming process ( . mj/kg of product) and lpg consumption was used for combustion in biscuit firing process ( . mj/kg of product) and glost firing process ( . mj/kg of product). thus, glost firing process was determined as a hotspot of energy consumption, accounted for . % of total energy consumption. the ghg emissions from ceramic tableware production were from the consumption of energy (electricity and lpg) and the decomposition of calcium carbonate (caco ) during glost firing, caco was one of glaze materials composition. total ghg emission was . kgco e/kg of product. from fig. , the largest ghg emission was from lpg during biscuit and glost firing ( . %), followed by electricity consumption ( . %) and decomposition of calcium carbonate ( . %). similar to the energy hotspot, glost firing process was also found to be the hotspot of ghg emission with the largest share of . % of total ghg emissions. thus, the energy conservation and ghg mitigation options for ceramic tableware production should be focused in glost firing process. table . energy consumption and ghg emission (per kg of product) unit process energy consumption ghg emission electricity (mj/ kg of product) lpg (mj/ kg of product) total (mj/ kg of product) % kgco e/kg of product % forming . . . . . drying biscuit firing . . . . . glazing glost firing . . . . a+ . b . a+ . b qc/packing total . . . . afrom lpg consumption bfrom decomposition of calcium carbonate panatda riyakad and siriluk chiarakorn / energy procedia ( ) – fig. . percentages of ghg emissions divided by sources from a stoneware plate production (gate to gate) . conclusion the total energy consumption from a -inch stoneware plate production was . mj/kg of product and almost % of total energy consumption was from lpg consumption during firing. the amount of ghg emission was . kgco e/kg of product. the shares of ghg emissions were from lpg ( . %), electricity consumption ( . %) and decomposition of calcium carbonate ( . %). glost firing was found to be a hotspot of energy consumption and ghg emission. acknowledgements the authors would like to express to their gratitude to the national research council of thailand (nrct) for financial support. the authors would like to thank chupra co., ltd. for their kind collaboration in data collection and field survey. the authors also thank lampang ceramic association (lca) for their kind collaboration and supports. references [ ] lathulee t, thongprasert s, thongprasert m. energy efficiency study in ceramic industry. ie network ; - . [ ] the office of industrial economics. industrial economic reports; . available online: http://www.oie.go.th. [ ] department of industrial works. standard industrial classification (thailand) tsic . available online: http://www.diw.go.th. [ ] quinteiro p, araújo a, dias ac, oliveira b, arroja l. allocation of energy consumption and greenhouse gas emissions in the production of earthenware ceramic pieces. journal of cleaner production ; : - . [ ] peng j, zhao y, jiao l, zheng w, zeng l. co emission calculation and reduction options in ceramic tile manufacture: the foshan case. energy procedia ; : - . [ ] intergovernmental panel on climate change (ipcc). ipcc guidelines for national greenhouse gas inventories . available online: http://www.ipcc-nggip.iges.or.jp/public/ gl. [ ] hanle l, maldonado p, onuma e, tichy m, oss hg. chapter : mineral industry emissions. ipcc guidelines for national greenhouse gas inventories, , , pp. . . [ ] thailand greenhouse gas management organization (tgo). emission factor cfp . available online: http://thaicarbonlabel.tgo.or.th/carbonfootprint/index.php?page= . summary of track : particle design – formulation and processing procedia engineering ( ) – - © published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). selection and peer-review under responsibility of chinese society of particuology, institute of process engineering, chinese academy of sciences (cas) doi: . /j.proeng. . . sciencedirect available online at www.sciencedirect.com summary of track : particle design – formulation and processing yongsheng han institute of process engineering, chinese academy of sciences, beijing, china this track was organized by professor jianfeng chen from beijing university of chemical engineering (focusing on the topic of particle morphology and size control), prof. dan wang from institute of process engineering, chinese academy of science (focusing on the topic of nano and superfine particles), prof. guanghui ma from institute of process engineering, chinese academy of science (focusing on the topic of biological particles), prof. fude cui from shenyang pharmaceutical university (focusing on the topic of pharmaceutical particles), prof. chunzhong li from east china university of science and technology (focusing on the topic of new approaches for particle preparation). track focuses on the particle design in formulation and processing, covering the areas of synthesis, characterizations and applications. more than oral talks and nearly posters were presented and the following issues have been highlighted: particles size and morphology in the last decade, the nanosized particles have attracted great attention due to their unique properties and potential applications. with the development of nanoscience, researchers have gradually come out from the fetishism on nano. in stead, they put more effort in the scale up and application of nanoparticles. in this congress, prof. jianfeng chen (from beijing university of chemical engineering, china) reported their strategy to produce nanoparticles with massive production at low cost by the high gravity controlled precipitation technology (hgcp). the morphology is another important issue of particles. various morphology-dependent properties have been found in the study of nanoscience, which promises that morphology control is the next big thing in nanoscience. the core/shell particles and two-dimensional particles have been highlighted by prof. zhiyong tang (from national center for nanosciecne and technology, china) and prof. hua zhang (from nanyang technological university, singapore) respectively. prof. wolfgang peukert (from university of erlangen, germany) gave a keynote talk on the design and controlled synthesis of hierarchical structures. the scientists from institute of process engineering, cas presented their original study on the control of hierarchical structures via regulating the chemical diffusion and reaction. particles preparation and characterization except the traditional methods for particles preparation, several new approaches have been reported in this congress. prof. yeukung hwu (from academia sinica, taiwan, china) gave a keynote talk on the synthesis of nanoparticles by x-rays which was used to reduce metallic ion precursors and achieved accurate control on the nucleation process, the size and shape of particles. prof. changjun liu (from tianjin university, china) used electron as a reducing agent to produce nanostructured particles. he pointed out that the electron is the greenest reducing agent for materials preparation. besides, microfluidic systems were highlighted by prof. guangsheng luo (from tsinghua university, china) and prof. liangyin chu (from sichuan university, china) for the preparation of functional polymeric particles. prof. jukka rantanen (from university of copenhagen, denmark) gave a review on the innovative manufacturing of future pharmaceuticals in which he pointed out that the flexible processing based on continuous manufacturing is needed for enabling on-demand manufacturing of personalized http://crossmark.crossref.org/dialog/?doi= . /j.proeng. . . &domain=pdf yongsheng han / procedia engineering ( ) – products with tailor-made characteristics according to individual needs. for the issue of particle characterization, the term “in-situ” has attracted great attention. dr. doris segets (from university of erlangen, germany) reported their study of the in situ characterization on particles size. another impressive report was given by mr. k gao who is a phd student of karlsruhe institute of technology. he used an in situ transition electron microcopy to observe the movement of metal cluster on the surface of oxide support, clarifying the debate of years on the transport routes of metal catalyst on support. the in situ characterization on the materials formation and application processes is expected to open the black boxes which impedes our understanding on many microscopic phenomena. particles applications the bright future promised by nanoparticles is the driving force for the continuous effort in discovering nanotechnology. bio and energy applications are two majorities in this congress. a team from prof. guanghui ma (from institute of process engineering, cas, china) has focused on the application of different particles in the field of pharmaceutics. another interesting talk was from prof. woo sik choi (from pusan national university, south korea) who reported their study on the healing practices and the user experience for pillows and mattress using loess ball bio-product. besides, cancer targeting has received great attention on both in vivo and in vitro studies. the reports on energy application include but not limited catalysis and energy storage. a team from prof. chunzhong li (from east china university of science and technology, china) reported their studies on the controlled synthesis of oxides for lithium ion batteries. prof. jian liu (from curtin university, australia) gave an invited talk on nanoporous colloidal carbon spheres for energy applications. the new ideas in designing and applying particles promises a solution to improve the efficiency of recyclable energy devices, finally leading to a green and sustainable approach to face the energy crisis. to sum up, particles are still hot topics in the fields of nanomaterials. except the control on particles size and the preparation of new morphologies, the fundamental study on the controllable synthesis and the advanced applications in energy and environments have attracted great attentions. all these works will push the development of particles materials and make them benefits to our life. . la-ur- : los alamos h’al,onal laboralor) is operated by ~ae un,ver$,ty o! cal,torma tor the unltect slale$ oeparlmenl energy “ntj~, cwi,ki w. . er.jg. fj title fuel cells for extraterrestrialand terrestrial applications author:s) supramaniamsrinivasan, (mee- ) la-ur-- - de subi\ tled to symposium on “’el~ctrode materials and processes for energy conversion and storage,” st meeting of the electrochemical society. philcidlilphia, pa mav o- , dmclaimer i“hls rcp,:l wiis prcpnrcd usun uccount of work spmrnwcd hy ur. ugcncyof the united stutcs (h)vcrntl,cnt. nciil?r(h [lrlltc[l st/ltcs (iovcrntncnl rim unytigcncy lhercof, nnrunydthcir ctnployccs, mukm ilny wurrllnly, cxprcsf or implied, or uwurncs urty lcgd iiuhility nr rcsponni. t~i!ily f,w the uccdrncy, conlplclcrww, (w u~cfulncw of uny informutim, upphrulu*, prducl,or prt.cw diwlmcd, {jr rcprc+cnts } its usc wiwiii trot infringe privutcly owned righ(t, refcr- cncc hcrcln ii) uny spccii’ic ctmmcrciul pr,nlud, prmcw, or scrvicc hy trudc numc, irndcrmrrh, munufllcturcr, or otherwise (km nut ncccwwrily constitute or imply its cndmxcrncnt, rcmrl- ttwnlltlt(m, or (iworing hy ihc [jnilcd siuicn (hwctnmcnt or uny ugcnq (hereof i’hc vicwx ,ind ,iplrlt(ms i)f ilu!hors cxprcwcd herein do not ncccwwrily \tmv (w icflct’t ihiixc of !hn ii iiiic(i stlltcq(;t)vcrnltlctll or, lnyllgcncythcrcttf ~va(, p ,ln~,cpt, fth, \a~l, <l? , p ,,,,,, . v ,wl~,i,,wbti!,ai i,wu a lnuvwi,,t*,wtttitw,~,tinmtou,oval,ti.,vv tuy*, tv, tewo,&@ttgw! uuuu,, bt, otfepfoti”cq ltlpptof!l,tt cd (,*n, o! lb!< tn.,~t,,jl,n?, nf lo nllow olh~ft to do fo~ () s (iovafnmenl duf doi?! t!,r i(in ain@~ii-. ndti(ififi i iat),,a,i),v tw,@bi% lhnl ii!p c)ut,i,qhe. ,dmnt, tv ih, n ntl,cl?aswo?h wvlofmea undarlho ausp,coaolthous @@n?lm@t\tnlln@tg) . . .— master losmk?ilmoslos alamos national laboratory about this report this official electronic version was created by scanning the best available paper or microfiche copy of the original report at a dpi resolution. original color illustrations appear as black and white images.
 
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 e-mail: lwwp@lanl.gov fuel cells for extraterrestrialand terrestrial applications s. srinivasan los alamos national laboratory ?!echanical & electronic engineering division, ?isd los alarnos, new hexico abstract the fuel cell is a nineteenth century invention and a twentieth century technology development. me to the high power and energy density, high efficiency, reliability, and production of pure water, hydrogen-oxygen fuel cell systems have no competition as auxiliary power sources for space vehicles. the alkaline fuel cell system is a well developed and proven technology for this application. the solid polyner electrolyte eyutem may be its future competitor. the energy crisis of stimulated research, development ●nd demonstration of the phosphoric acid, molten carbonate, solid oxide and solid polymer electrolyte fuel cell systems using natural gas, petroleum or coal derived hydrogen (and carbon monoxide for the high temperature uyetems) for terrestrial applications. the direct methanol-air fuel cell is still an electrochemist’s dream, though considerable technological advances have been made, tha prenent price of cmde oil, and the high c~pital cost-s and limited lifetime of fuel cell systems impede their terrestri~l application in the developed countries, conversely, tha potential for lower capital cosls of labor intensive manufacturing processes and the r~latively higher fossil fuel prices make these eyu~ems more atti”activo for such applications in the developing countries, ~he fuel cells - a nineteenth centuryinvention and ~entimh century ~~chnolwy dl!velophetjt——— _ —. though sir william grove discovorod fuel cells as early as , it was only in tho ’s that fuel cell oystem. found their flrot major application-auxiliery power sources for the gemini opsce flights. however, a number of concepts relating to tho ●dvantages of convort!ng chemical energy to electrical energy, typas of fu~ls, and tcmperaturo rmngeo for oporation k were alluded to in the research work during the intervening years. - though the historical development of fuel cells has been covered adequately in several books and review articles, it is worth summarizing the highlights the progress made in this period. ● sir william r. grove demonstrated the first fuel cell in by of supplying hydrogen to one platinum electrode and oxygen to another with both electrodes contained in sulfuric acid. he connected six of these fuel cells in series and used the electricity generated to decompose water. platinum is still the best elactrocatalyst for aqueous electrolyte fuel cells! ● becquerel devised a fuel cell in consuming carbon by immersing it in molten nitre (potassium nitrate) contained in a platinum vessel. platinum also served as the counter electrode. the faradaic efficiency was low because of the direct chemical oxidation of carbo~ by potassium nitrate. ?lond and langer ( ) developed a fuel cell battery in which platinum sheets with many small holes and covered with platinum black ware used as electrodes, dilute sulfuric acid, retained in a porous plaster-of-paris matrix, served as the electrolyte. * ostwu!d ( ) recognized the potentially high efficiency of fuel cells, i.e., the conversion of the free energy chanve of a chemical reuc;tion directly to electricity. ● jacqu@s ( ) designed and built a , icw fuel cell b~ttery, each cell. consisted of an iron pot containing fused sodium hydroxide into which was placed a carbon rod as the consumable anode, ● the pioneer of the fuel co l nra in the twentieth century is francis t. bacon, he started the development of ● hydrogen/oxyben fuel cell battery in a kw fuel cell power plant was built and tested in in : k orcler to stabalize the gas and electrolyte within the electrodes, these were of a dual porosity construction (teflon was not discovered at that time) . the single cell consisted of a lithiated nickel oxide cathode and % and pressures were - ”c and to sintered nickel anode, sintered koh. the operating temperatures atm. ● the bacon fuel cell system served as thl~ foundation for the fuel cell power plants (auxiliary power sources) for the apollo space vehicles, developed by pratt and uhitney aircraft., division of united technologies corporation. the energy crisis of was the impetus for a large number of research and development programs on fuel cell technology for terrestrial applications. the status of fuel cell technologies for extraterrestrial and terrestrial applications is summarized in the next two sections, while the final section deals with the prognosis of economics and applications of fuel cell systems. before dealing with these topics, it if worthwhile recollecting some fuel cell principles in respect to systems engineering aspects: ● the fuel determines type of fuel cell and fuel processor. ● the operating temperature determines method of product heat and water removal. ● the application determines power rating, need for bottoming cycle, pow?r conditioning and scale-up considerations. ● start-up time and peaking capabilities are of primary concern in respect to developing fuel cells for tranapf)rtation ●pplications. ?t~ the heart of the fuel cell system is the electrochemical cell stack. ‘ ‘,s .b its basic components are the porous gas diffusion electrodes, electrolyte which may or may not be held in a matrix and the bipolar ;+ plnte , their choice design and fabrication procedure is ●gain -j’ ) determined by the primary fuel ●nd by the operating temperature and pramuure of the fuel cell power plant. e the space age - the first h.ajorapplication of fuel cell systems the main advantages of fuel cell systems for space applications are high power and energy density with respect to weight and volume, high efficiency, few moving parts, minimum noise and vibration and reliability. for this application, the logical fuel and oxidant are cryogenic hydrogen and oxygen. the gemini space flights used a kw general electric solid polymer electrolyte fuel cell. the distinctive feature of this cell is that a solid electrolyte was used in the form of an ion exchange membrane (polystyrene sulfonate). the two electrodes which consist of the electrocatalyst (finely divided platin~) and a plastic material for wet-proofing the electrode are incorporated on fine metallic (platinum or titanium) wire screens. these electrodes are bonded on both sides of the solid polymer electrolyte. metallic current collectors are ribbed on to each electrode. the heat renoval was by circulating a coolant through tubes in the bipolar current collector to a space radiator. wicks were used on the cathode side of the current colloctor to absorb the ]~roduct water and carry it over by capillary action. the water ( pint/kwh) was used for drinking purposes by the astronauts. the gemini fuel cell ~;ystem was used for missions of duratioa about - weeks. though it satisfied the perfomnance requirenlentr for such flights, there were some problems with this technology - the power der~sities attained were not high enough; the polystyrene sulfonate ion exchange membrane electrolyte ws not stable u~cler the electrochemical environments in the cell; and, the platinum loading was quite high. thus, the alkaline fuel cell technology was chosen for the a,q and space shuttle flights. the pratt and whitney division of united technologies co~oration developed alka]ine fuel cell systems for the apollo flights - these fuel cells used the b&con fuel cell technology with dual porosity electrodes (nickel for the anode and lithiated nickel oxide for the cathode). the dual porosity electrodes served the purpose of stabilizing the electrolyte meniscus within the elect~-ode. unlike the bacon fuel cells, these cells used a high concentration potassium hydroxide ( - % whi~h is practically the molten salt), at a higher temperature ( ” rather than atmospheric pressure; r~markable improvements in sc) and close to performance have been reported in futuristic versions of the alkali fuel cell power plants for the space shuttle flights and these are illustrated in figure . the electrodes are teflon bounded and contain unsupported platinum (anode) and gold-platinum alloy electrocatalysts. the main difference in the electrochemical cell is the use of an extremely thin ( o vm) electrolyte matrix made with potassium titanate. figure shows that extremely high current densities are achieved in the purely activation controlled region (about . a/ctr at . v), while the slope of the linear region is amazingly low ( . ohm cm ). this low vaiue of the slope is essential for attaining high current densities (up to a/cm*) at moderate cell potentials ( . v). the apollo fuel cell systems (rated power about khl) performed quite satisfactorily for missions which lasted - weeks. for the space shuttle flights of the ’s and ’s, united technologies corporation/international fuel cells corporation, developed a high performance alkaline fuel cell systeu ( w), with platinum anodes ( mg/cm of pt), and gold ( %) - platinum ( %) cathodes ( mg/cm of au-pt alloy). the electrolyte is % koh and is immobilized in a reconstituted asbestos matrix. an electrolyte reservoir plate is on the anode side to supply electrolyte when needed. the cells operate at about - ”c under a few atm pressure. current densities of about a/cu at cell potentials of , v are obtained in these cells. the objectives of bjasa are to further improve the performance of these cells by increasing the operating temperature to about °c, for this purpose, the gold-platinum electrocatalyst will have to be modified to i~rove the performance and increase the stability, perhaps by incorporating a third component in the alloy, a strong competitor for the alkaline fuel cell system is possibly the advanced solid polymer electrolyte fuel cell. recent results from siemens, gemnany; ballard technologies corporation, canada; and los alsunos national laboratory (lanl), ijsa, strongly indicate the ttainment of high power densities with stablc~ membranes (for example, mefion and dow hembranes) and low noble metallic loadings ( . mg/cm ). current densities of emp/cm at a cell potential of . v, ”c and atm pressure have been reported by ballard technologies corporation and siemens in s~lid polymer electrolyte (dow membrane) fuel cells with tefjon bonded electrodes containing mg/cm unsupported platinum. the reactants are pure h and . the los alamos e national laboratory investigators are focussing on achieving high power densities in such fuel cells using low noble platinum loading - electrodes. the manner in which this is achieved is by impregnation of a proton conductor (e.g., tjafion) into a *’conventional*” porous as diffusion electrode used with liquid electrolytes. the rationale for this approach is that the reaction zone for a fuel cell reaction at a solid electrodelsolid electrolyte interface is <lose to a *’three phase line.” impregnation of the proton conductor into the electrode structure considerably extends the three phase zone and approaches that in the case of a liquid electrolyte. current densities of a/cm have been attained at cell potentials of . v. the slopes of the linear region in the cell potential–current density plots are . and , ohm cm for the ballard technologies corporation and lanl single cells, respectively, the main reason for the lower slope, which is central for attainment of higher current densities appears to be the use of the dow membrane in the former and the nafion membrane in the latter case. the dow membrane used by ballard technologies corporation has a smaller thickness ( vs jsn), higher acidity and better water retention characteristics than the i#afion membrane used in the lanl single cells. the ballard fuel cells were also operated at a higher pressure ( vs atm) than the wl ones. the energycrises of - a renaissanceof fuel cell technologyfor terrestrial applications the nasar&d programs on fuel cell technologies initiated in the s ’s, stimulated similar programs in the usa and several european countries during this and succeeding decade for terrestrial applications. considerable efforts were made to use fuels such as natural gas, the higher hydrocarbons, methanol, ethanol and other organic fuels, directly in fuel cells. in the latter part of the ’s, the interest faded away because of the low efficiency and power density achieved in fuel cells which use organic fuels dir ctly as the anodic reactant. united technologies corporation (utc), with their strong ‘“forte” in alkaline fuel cell technology for extraterrestrial applications, also provided leadership in the development of fuel cells for terrestrial applications. even prior to the energy crisis of , utc embarked on a progrm with some support from electric and gas utilities to develop fuel cell power plants utilizing natural gas. such types of fuel cell power plants being considered as substitutes for gas turbines whic~ were and still are being used as peaking devices in electric utility power plants. were the energy crisis of was the ●’rationale*’ for renaissance of fuel cell technology for terrestrial applications. the energy research and development administration (erda which subsequently became the u. s. department of energy) and the electric power research institute (epri) stressed the need for conservation of the petroleum fuels and for the increasing utilization of coal, natural gas, and renewable energy resources. the potential benefits of fuel cell power plants for peak shaving, load following and intermediate and base load power generation in electric utility applications are: ● the chemical energy of a fuel is directly transfomned into electricity. thus, the theoretical efficiency is not limited by the carnot cycle as is the case for conventional themal power plants. fuel cell power plant efficiencies are independent of the rated power above say about w. this is not so with oil or coal burning power plants, gas turbines, and diesel generators, where the efficiency is reasonably constant only at ● fuel cells can be made in a permits locating such power the megawatt power level. variety of sizes and they are modular. this plants at several grid systems to reduce transmission line costs, con~ested urban centers, facilities are expensive ● the siting advantages of this advantage is particularly important in where the needed transmission and distribution to install; fuel cell power plants can be extended because of their capabilities for waske heat utilization (as for example, space heating, hot water, and absorption cooling). the combined efficiency for electricity and heat production can be as high as %, this is quite attractive for gas utilities having extensive gas distribution systems ~%, ,* \& \l i’ t ~. ‘ .,) \u u“ \ e ● fuel cell power plants make a lot of sense for installation industries which need both electricity and high grade heat. in large in the late ’s, programs were initiated at brookhaven national laboratory and los alamos national laboratory for the investigation of fuel cell power plants for vehicular power plants. some of the above advantages of fuel cell power plants over thermal ones for electric and gas utility power generation apply equally well for vehicular power plants. the significant one is that the projected efficiencies for fuel cell power plants are at least twice as high as internal combustion and diesel engines. in the ’s, it was realized that because activation overpotentials for anoclic oxidation of organic fuels are too high and poisoning problems by their intermediates are encountered, it is necessary to process these fuels to hydrogen prior to entry into the electrochemical cell stack. in the high temperature fuel cell systems, carbon monoxide is also an efficient anodic reactant, natural g~.,s and coal are the primary fuels of most interest for terrestrial applications of fuel cells. methanol, a liquid fuel which is mass produced from natural gas and in the future possibly from coal, is another attractive fuel, particularly for transportation applications. this fuel is the most electroactive organic fuel but its activity is about three orders less than that of hydrogen, thus , at the present time, even methanol will have to be ste~-refo~ed to hydrogen before entry into the anode gas chamber. the processing of organic fuels restricts electrolytes to carbon dioxide rejecting ones - phosphoric acid, molten carbonate, solid oxide, and solid polymer electrolyte (the last is with processed methanol as fuel). the following subsections briefly describe the status of each of these technologies. for more details, the reader is referred to recent , publications, phosphoric acid fuel cell systems: apart from the alkaline fuel cell systems for space applications, this technology is the most advanced. systems ranging from khl to w have been designed, built and tested. the most advanced version ~perates at ”c, atm pressure, at a current density of ma/cn and . v/cell. the noble metal loading of the anode is . mg/cm e and of the cathode is . mg/cm . some platinum alloy electrocatalysts (with cr, v) si.owimproved performance but lifetime is a problem. these sygtems are being considered for load following in electric utilities and on site integration energy systems. the chemical + electrical energy conversion efficiency at the rated power level is about % and chemical + (electrical & heat) energy conversion ~~fficiency is over ~. lifetimes gf over years have been attained on demonstration systems. the materials used for the fabrication of components in a phosphoric acid fuel cell are shown in fig. . the anode and cathode consist of porous gas diffusion electrodes. these electrodes earl be prepared by one of three methods. the spraying ❑ethod (fig- ), many steps of which can be automated, is the most conunonly used. filtration and rolling methods are also used. the fomer is good for preparing experimental electrodes for research purposes. the rolling method is somewhat tedious, but result in electrodes which are reproducible from the point of view of electrochemical perfownce. the silicon carbide matrix (about - pm thick) is generally deposited on top of an electrode (say, cathode) by a wet process which involves preparation of a silicon carbide - teflon emulsion and bpra:*ing or continuous feeding to the electrode . the purpose of the small quantity of teflon is to serve as a binder, the electrode-silicon carbide assembly is then heated to dry the matrix and sinter the teflon in it. the porous carbon serves three pu~oses - it is grooved to permit gas distribution; in the united technologies corporation design it serves as an electrolyte reservoir; and it is a current collector. the active layer in the electrode consists of platinum supported on carbon and teflon. the teflon content in the layer is about %. platinum crystallite are deyosited on the high surface area carbon generally by m collcidal method followed by heat pretreatment. the aim is to have platinum crystallite with a diameter of about a“. an electron microscope photograph of the supported electrocatalynts ib shown in fig. . one of the perfomed degradation mechanism~ in fuel ceils electrodes is the agglomeration or sintering of platinum cry tallites, causing loss of electrochernicelly active surface area. phenomenon is due to e !-- ‘ is generally qccepted at the prysent timo that khis surface migration of platinum crystallite, iollowed by their coalescence. the low significantly influenced by the electrolyte. another temperature sintering is cause for performance degradation is poisoning of mainly the anode. poisons which can be encountered are co and h s from reformed fuels, organic impurities in cell component materials and metallic impurities, from say cooling pipes. plans are underway to build and / uwphosphoric acid fuel cell power plants by international fuel cells corporation (a division cf united technologies corporation) and westinghouse corporation. figure , a schematic of the fotmer one, demonstrates that the electrochemical cell stack is a small but vital component of the entire system. these power plants are being considered for ‘*load followers” by the electric utilities. such types of power plants are being strongly identified in japan for the stated and dispersed power generation applications. toshiba is in international fuel cells corporation for the development and installation of these plants. molten carbonate fuel cell systems: this is en ideal system to types of power be used with reformed natural gas and gasj.fied coal. progress has recently been made at energy research corporation for the internal reforming of natural gas (i.e., with catalyst system ahead of the anode). this eliminates a major component - the fuel processor. carbon monoxide produced from natural gas or coal is a reactant and not a poison for the molten carbonate fu cell system unlike in the phosphoric acid fuel cell system. the components of the single cell in a molten carbonate fuel cell are represented in fig. , the electrolyte (lithium and potassium carbonate) is held in a tile (lithium aluminate). the anode is made of porous nickel and the cathode of porous nickel oxide. the reactions in a molten carbonate fuel cell are depicted in fig. . the cathode material is transformed into lithiated nickel oxide by its interaction with the electrolyte. lithiated nickel oxide is a better electronic con uctor and also more corrosion resistant than nickel oxide. however, corrosion of the cathode material is one of the most serious problems in this fuel cell. use of wi-cr or ni.-cu alloys inhibits the sintering of the ui and the presence of cr reduces the sulfur poisoning. attempts are being made to find spinels and perovskites as substitutes for the lithiated nickel oxide cathodes which tend b to corrode nlowly in the electrolyte. the bipolar plate conoints of two layers - nickel on the hydrogen side and stainless steel on the oxygen side. the morphology ~d porosity of each of the cell components is sho~ in fig. . the pores in the electrolyte tile are relatively nmall compared to those in the electrodes. activation overpotential losses are minimum in thin cell. the cell potential - current density relation is linear (fig. ) and the cells are designed to operate at . v and ma/cm . the slope of this line is about four times as high as in the linear region of the same plot for the phosphoric acid fuel cell system. high grade heat, liberated by this system, can be used for electr],city generation in a gas turbine or used as such by chemical industry. efficiencies for electricity generation as high as % are projected. molten carbonate fuel cell programs are ongoing in the u,s.a., japan, and italy. fuel cell powerplants with an electrode area of / to m are plnnned to be built. the multicell stack will consist of to cells, each of these will deliver a power output of ku to ?fu. international fuel cells corporation is the fore~nner for th~ development of molten carbonate fuel cells, there are two lines of approach. one is to build a stack with electrode area of . m and the other with that of . m , the arean of active research ace (i) i~roved electrolyte management, (ii) stabilization of cathode, (iii) reduction of anode compaction and low cell to end plate resistance; and (iv) examintition of effects of h s on molten carbonqte fuel cell perfomnance, solid electrolyte fuel cell systems: the rationale for developing solid electrolyte fuel cell systems is its high projected efficiency for electricity &aneration, by using gasified coal, ag compared with those of the phosphoric acid end molten carbonate fuel cells, a ochematic of a oolid electrolyte fuel cell power plant is shawn in fig. . in recent years, attention has been focuaaed on natural gag, iasteud of coal ●b the primary fuel. thio is beta’~se of th) vast proven resemes of this fuel in many countries including the u.s.a. it i- ●lso simplsr to process natural gas than coal to tha fuel call fuels (h ●nd co). the proceseod fuel enters the electrochemical cell stack where tho chemical energy of the fuel is tran~formed to electricity. this p, o ~ql [’& ji rfq ;’\ e t;\du fuel cell with the yttria stabilized zirconia ( % yttria in zirconia) electrolyte operates at ”c. the high quality waste heat enters the steam generator which in turn s’ipplies steam to the steam turbine to produce more electricity. the total efficiency for the production of electrical energy from the chemical energy of coal or natural gas using tl~e fuel cell system and the gas turbine is projected to exceed %. rapid advances in this technology have been made at westinghouse corpmation during the last s years. l%is is in respect to a tubular ciesign (closed at one end) with connections of cells in series and parallel. layers of the cathode, electrolyte and anode material are deposited on the closed end porous zirconia tube (see fig. ) by chemical or electrochemical vapor deposition techniques. the cathode of one cell is connected to the anode of the next cell by a strip of interconnection and nickel felt. two cells are connected in parallel with a nickel felt. the series - parallel connection in four cells is represented in fig. . the nickel felt is in a reducing environment and is stable. nickel is the anode electrocatalyst and strontium doped lanthanum ~nganite the cathode electrocatalyst. magnesium doped lanthanum chromi!,e is the material used for the interconnection. the operating temperature is ”c. the cell potential-current density relation is linear. the slope is relatively high - about . o?un/cii! . thus, the current density at about . v is about ma/cm . the improvement in performance of oxygen over air, as seen in fig, , is due to thermodynamic, electrode kinetic and “barrier layers” effects. the h /air fuel cell performance can be improved by minimizing the “barrier layer” effect, i.e., reducing the thicknesses of the support tubes, and of the cathode layer as well as increasing the porosity. the power versus current or current density plot is also shown in fig. . each tube has a designed power output of watts, the cell performance is stable over several hundred hours, this led to the design, engineering and construction of multicell stacks, a fuel cell bundle consists of twelve tubular cells, arranged in a three-parallel by four series matrix. a series connection af two bundles is made at one side and power terminals are connected to each of the bundles on the other side. thus, the twenty-four cells exhibit ●ight times n voltage and three times the current of a single cell. ?-~ pi \b , ~’ [ rf’ “,tl ;u@” the generator which consists of the twenty-four cell stacks also has a thermal insulation package. the latter includes the cell-support etructure snd gas distribution systems. the temperature distribution within the cell bundle is maintained only by waste heat generation from the fuel cells and combustion of the spent gases in the exhaust chamber ( % of supplied fuel). heat exchange in the spent fuel combustor preheats the inlet air supply and limits the exhaust gas temperature. the successful design, construction, and performance evaluation of the -cell stack led to the construction of a ku fuel cell generator. this multicell stack consists of single cells. the sub-cell stacks, consisting of the cells, are connected in series to form the multi-cell stack. performance evaluation of the w fuel cell system is now in progress. like in the molten carbonate fuel cell system, hydrogen and carbon monoxide may be ueed as processed fuels. ~ain, because of the high grade heat, it is designed to senerate more electricity in a bottoming cycle or be used as such for cogeneration applications. efficiencies for electricity generation will be higher than that for the molten carbonate system. ~lid polymer ulectroiyte fuel cell systems: thir system is being considered for transportation application. since the system operates at less than ”c, methanol is the most appropriate liquid fuel to be reformed and used in this fuel cell system, as stated in the preceding section, progress had been made lt los alamos national laboratory to reduce the noble metal loading to one tenth that in the state-of-the-art iystem developed by general electric company/hamilton standards, this is done by incorporating a proton conductor into the electrode structure to extend the three dimensional reactor tone, the water management in the system can be ●chieved by optimum humidification of tim system, prospects are good for attaining high power densities - over mw/cm . pi-t hethanol ?uo cell: a fuel cell researcher’s dream: a fuel cell researcher’s dream in to oxidise organic fuels (preferably methanol which is ●asily produced from natural gee or coal) rather than process these to hydrogen, which is in tu oxidiaaid to hydro~en in the electrochemical call. ~!!ifl “ j“ \ \\ t ? e p!,’ ‘\\. [ w’ , ‘b) methanol is the most active electroorganic fuel but its activity in three orders of magnitude less than that of hydrogen. thus, under these conditions current-densities of about ma/ck ●i-e obtained at cell potentials of . v. even at these cur~-ent densities, there is a performance degradation with time. the main cause for i~ is that the intermediates formed during methanol oxidation poison the platinum electrocatalyst. the poisoning effects are less with some alloy elgctrocatalysts (e.g, pt-ru, pt-sn) and platinum electrocatalysts with ad atoms (bi, pb, sn, gel. the probable mechanisms for inhibition by such electrocatalysts is that the second elements is either in an oxidised state which catalyzes the oxidation of the organic intermediates or an inhibitor for hydrogen adsorption on platinum, thereby preventing the formation of a hydrogenated organic inhibitor. attempts have been made to oxidise methanol in a phosphoric acid fuel cell at elevated temperatures (say °c). in this case, methanol was fed as a vapor into the cell. the main problem was from the anode to tho cathode where it acted reduction reaction. that unreacted methanol migrated as a depolarizer for the oxygen prognosis of economicsnd applications of fuel cell syst~s.— thta applications of fuel cell systems have been well demonstrated in space vehicles, capital costs are not such an overriding factor for space applications as for torresirial applications. the alkaline and posuibly the solid polymer {~lectrolyte fuel cell systems will continuo to ba the ●uxiliary power sources for space vehicles. regenerative fu~l cells will have to be developed for long space flights (more than a few months) and space laboratories, the present price of crude oil makes it more difficult. for the ●ntry of fuel cell systems into the terrestrial ● rena particularly in the dweloped countries, fuel cells may find nearer term replications in tho developing countries, particularly for dispersed power generation uning biomess fuels (biogas, alcohols). since the manufacturing processe~ for fuel cells ● re labor intensive, the capital costs of these systems could be coi~siderably lower in the developing countries, further, the cost of fuels in these countrios ● re realistically and relatively (~n respect to per capita income) higher in the developing countries, thus, the need for fuel cell technology f flu . ,. is higher in the developing countries. in the developed countries, fuel cell technologies can make an impact on-site integrated energy and cogeneration applications, environmental constraints can also accelerate the entry of fuel cell technologies. the bottom line with respect to economics of fuel cells for terrestrial applications, will be the cost of electricity generated, which in turn will depend on capital costs, efficiency and lifetime.taking into consideration the performances of the four types of fuel cells for terrestrial applications, the major factors to be overcome are: (i) develop automated techniques to reduce the capital costs of the system to about $ -$ /ku (high capital cost at the i@ level and lower at the hw level) for stationary applications and $ /kw for transportation applications; (ii) achieve reliability of performance ~ter the required lifetimes; (iii) demonstrate economic, technical and environmental advantages of dispersed, on-site integrated energy and cogeneration power plants; and (iv) find niche for electric vehicles - in plant, military, buses, trucks, and automobiles? the factors which impede tha commercialization of fuel c are: ● capital cost, operating cost, lifetime, reliability, weight, and volume. ● capital costs and powerlweight and powerlvolume which &re primarily dependent on power density. ● operating costs which are detemined by amortization of capital costs (hence lifetime) and efficiency, ● material costs of fuel cell components which are relatively low except for the solid polymer electrolyte fuel cell system, ● capital coste which are relativ~ly high becausa manufacturing coots are labor intwwive, ,, “ b ● for fuel cell systems to have an efficiency greater than %, single cell potential must be greater than . v (i.e., half the thermoneutral potential for the reaction ha + / . + hoo which is . v. ● open circuit potential for all fuel cells is attain high current densities with this open approximately . v. to circuit pot~ntlal and cell potentiel of . v, the slope (de/di) in the linear region of the cell potential versus current density plot has to be small, say about . ohm cm . the lowest values of (de/di) reported for the five types of fuel cell systems are found in table i. it can be readily seen from this table that the only fuel cell systems which can attain high current densities arc the ones with alkaline and solid polymer electrolyte. the phosphoric acid fuel cell system is considerably closer to attaining higher current densities than the molten carbonate or sulid electrolyte fuel cell systems bectiuse of tha respective (deldi) values. this work was carried out under the auspices of the u. s department of energy. the author wises to thank dr. jack t, brown of westinghouse corporation for lendi,~g the slide material on solid oxide elclctrolyte fuel cells, which wore quite valuable for the preparation and presentation of this paper, references , j.o’m. bockris, and s, srinivauan, fuel calls: their electrochemistry, mcgraw hill publishing company, * k. v. kordosch, j, igloctrochem, new york ( ). c., , ??c ( ). . s, s, pomer, lm,, assessment of research nods for advanced fuel calls, ! r \ . . , . . , , . *r ,\ ‘“\\’#* h. t. r. haget, chapter in c. berger, ed. , handbook of fuel cell technology, prentice hall, inc., englewood cliffs, nj ( ). c. c. rrill, proc. ann. power sources conf., , ( ). . d. raistrick, proceedings of the symposium on diaphragms, separators and ion exchange ?fembranes, - , electrochemical society, inc., princeton, wj ( ). s. srinivasan, e. a. ticianelli, c. r. derouin, and a. redondo, j. power sources. in prass. e. a. ticianelli, w. paik, c. r. derouin, i. d. raistrick, a. redondo, and s. srinivasan, extol, abs,, st meeting of the electrochemical society, honolulu, hawaii, october - , . in press. p. stonehart, b. d. mcnicol, e. j. taylor, mid s. srinivasan, chapter in b. d. tlcblicol and d, a. j. rand, eds., power sources for electric vehicles, elsvier, amsterdam ( ). fuel cells: technology status report, !!organtown energy technology center, u. s, department of energy, report #doe/hetc- - (de ), plorgantown, west virginia ( ). if ta le i lowest values of s opcs of linear reftions of cell potential- current density plots@e/di) reported for the five types ~f puel cells type of fuel cells ~de/di), ohm cm~ alkaline - solid polymer o- o phosphoric acid - molten carbonate - solid electrolyte o- e l-. -y . . m newcedwemh .s u# “eer i porousanduchve gra~ite l~er !i i anooe pofous p~suppxted wi cafbon m!h a teflon binder i i elictroiyt[ w(i. m an inarl sititxtn-based mattix i ! i porouscoiw!uct*graphitelayer i fuel cell electrode fabrication spraying method r i -— pt on c catalyst teflon foto flow water i mixing r-+homogeneouscatalyst mixture i drying pre$kmjg sint;ring ) i backing i i diffusionlayer i i i i spraying i pressing sint;ring .= ..-”. e& ‘.. c.- - t&l~,-..- [!jt!!jtlr!!ja w-—--”” t ii—— ... . . ~;~ g -“ -“ ~ = -...”.. --g- i ----— i #i side of bilayer cell separator plate i t fine-pore ni anode: porous ni bubble-barrier i electrolyte: li/kc supported onineti lia! i cathode: porous nio pui keted stainless steel current cokxtor stainless steel side of bilqer cell separetor pltie molten a carbonate fuel cell construction materials ““ r tsfw% + c + h-~cof oxidant air + c catmode exhaust overall nwnoa—— . ,, .\. ..:::..:::..:....= \ . ●✎ “t o i i w la $ m z*o s hot fuel~ co:::::ioni steam sofc w generator air ~ ! d-c. steam turbine !nverter a.c. generator \ \ - / combined a.c. output interconnection air electrolyte ● \ir fk-rtti i-in: \fujird bnttunum mangantic slurw coal/sinlrr (c-*) %kl eklrc+w o l-a-)- yiiru- &lizd zirconia evd” inlmrmnrcfwl o(b? mdird laiwiunuwi chrunilc e\’d” fur! fm d nfh-) nkkaz+caliack-wklw sjurw ccd/stnlrr ( an(&) ca’dl-zlnxnw gllwl cell-well connecllon in the m)lid oxidi! fuel cell -———- ----- —. —.. - -—- . . ‘ *, ,< use of pcm r for thermal energy storage in modular heat exchanger for free cooling @ijrter- , all rights reserved icnscet - international conference on new scientific creations in engineering and technology use of pcm r for thermal energy storage in modular heat exchanger for free cooling m.thambidurai . l.sundararajan department of mechanical engineering, government college of engineering, sengipatti, thanjavur- , tamilnadu, india. department of chemistry, government college of engineering, sengipatti, thanjavur- , tamilnadu, india. abstract— a thermal energy storage system (tes) has the advantage of an efficient use of energy by reducing the imbalance of an energy demand between daytime and night time. it is classified as sensible and latent heat storage systems. the latent heat storage system is superior to the sensible heat storage system since the former reduces the installation area and the expense due to a large thermal storage capacity and constant phase change temperature during freezing and melting processes. phase change material (pcm) has been used as a medium of energy storage. an experimental investigation is carried out in the present research the setup includes a room of size x x feet which is needed to be cooled using the heat exchanger and study the technical feasibility of using r as pcm in a heat exchanger for free cooling applications. the charging and discharging experiments revealed the decline in the pcm temperature from °c to . °c. the pcm showed a gradual increase in its temperature from °c to °c during the discharge process after which the increase was rapid. keywords— latent heat thermal energy storage; phase change materials; free cooling; cool energy; green buildings; energy savings; modular heat exchanger. i. introduction efficient and economical technology that can be used to store large amounts of heat or cold in a definite volume has been the subject of research for a long time. latent heat thermal energy storage (lhtes) systems have been gaining importance in such fields as solar energy systems, district heating and cooling systems, energy efficient buildings, cool storage systems for central air conditioning systems, and waste heat recovery systems. there are many lhtes systems used in practical applications. phase change materials (pcm) are promising candidates for consideration as heat storage media due to their large energy storage capacity. free cooling is the process of storing the cool energy available in the night time ambient air in a storage device in order to cool the building during the daytime using mechanical ventilation system. thermal energy storage systems provide the potential to attain energy savings, which in turn reduce the environment impact related to energy use. these systems provide a valuable solution for correcting the mismatch that is often found between the supply and demand of energy. latent heat storage (lhs) is a relatively, a new area of study and it received much attention during the energy crisis of late s and early s, when it was extensively researched for use in solar heating systems. when the energy crisis subsided, much less emphasis was put on lhs. although research into lhs for solar heating systems continues, recently it is increasingly being considered for waste st international conference on new scientific creations in engineering and technology (icnscet- ) international journal of recent trends in engineering & research (ijrter) special issue; march - [issn: - ] @ijrter- , all rights reserved heat recovery, load leveling for power generation, building energy conservation and air-conditioning applications. as the demand for air-conditioning increased greatly during the last decade, large demands of electric power and limited reserves of fossil fuels have led to a surge of interest with energy efficient applications. electrical energy consumption varies significantly during the day and night according to the demand by industrial, commercial and residential activities. in extremely hot and cold countries, the major part of the load variation is due to air-conditioning and domestic space heating, respectively. this variation leads to a differential pricing system for peak and off-peak periods of energy use. better power generation/distribution management and significant economic benefit can be achieved if some of the peak load could be shifted to the off-peak load period that can be achieved by thermal energy storage for heating and cooling in residential and commercial building establishments. ii. experimental investigation the experimental setup consists of a cabin of dimension ft x ft x ft and a flat plate modular heat exchanger that contains ten rectangular shape stainless steel panels filled with phase change material. the cabin and the modular heat exchanger are connected through a well-insulated duct and a blower is used to circulate the air through the heat exchanger. a chimney is constructed on the roof top to aid the effect of natural convection. the photographic view of the experimental cabin along with the modular heat exchanger is shown in fig . considering the diurnal temperature variation of the pune city, a suitable pcm with phase transition temperature of approximately °c to °c is required for charging and discharging. the pcm, rt , which is one of the commercial grade pcm available with rubitherm, is selected for the above-said requirement. the technical specifications of the selected pcm provided by the manufacturer are given in table . fig : a photographic view of the experimental cabin with the modular heat exchanger st international conference on new scientific creations in engineering and technology (icnscet- ) international journal of recent trends in engineering & research (ijrter) special issue; march - [issn: - ] @ijrter- , all rights reserved table properties of the selected pcm (rt ) melting area - °c congealing area – °c latent heat (from to °c) kj/kg heat storage capacity kj/kg specific heat capacity (solid) – (liquid) j/kgk solid density kg/m liquid density kg/m heat conductivity . (solid) – . (liquid) w/mk the flat plate heat exchanger selected in the present study has modules which are stacked one over other with mm air gap between each module and it provides a flexible surface area, area/volume ratio. a small fan which is driven by a fan of capacity . kw is used to accelerate the air flow through the heat exchanger during the charging process. further, this heat exchanger has the facility of controlling the air space between the plates to vary the mass flow rate of air. this heat exchanger offers a very low pressure drop compared to the packed bed arrangement. considering the above technical advantage, in addition to the ease in construction, a flat plate modular heat exchanger is chosen for the present investigation. the plates are fabricated with stainless steel of grade and the outer casing of the heat exchanger is made of a mild steel plate, with a thickness of . mm and covered with a mm thick polystyrene insulation. the dimension of the modular heat exchanger is shown in fig , and table shows the details of the modules in the heat exchanger. fig . dimension of the modular heat exchanger table . details of the modular heat exchanger module length . m module width . m module thickness . m. volume of one module . m number of modules mass of pcm in one module . kg. the temperatures of the air at the inlet and outlet of the modular heat exchanger are important parameters for evaluating the energy transfer to the pcm modules. the temperature sensors used to measure the temperature are wire type rtd (pt ) with a range of – °c and an accuracy of ± . °c. two rtds are kept at the inlet to the room and the average value is considered as outlet temperature of the air from the modular heat exchanger. one rtd is kept near the entry to the st international conference on new scientific creations in engineering and technology (icnscet- ) international journal of recent trends in engineering & research (ijrter) special issue; march - [issn: - ] @ijrter- , all rights reserved modular heat exchanger to measure the inlet air temperature. pcm is measured using the rtds which are fitted in three locations in three modules of the modular heat exchanger. the average temperature is considered as the pcm temperature. six rtds are kept at different locations of the cabin to measure the average interior temperature of the cabin. the temperatures at various locations are monitored continuously, using a data acquisition system, which has an accuracy of ± . °c the experiments were conducted from . am in the early mornings during the month of november and december and these duration matches well with the major weather conditions prevailing in pune city. several experiments are conducted to study the characteristics of phase change material during the charging process. air at a mass flow rate of kg/sec is allowed to pass through the heat exchanger. the temperature of the pcm in all the selected locations in the modular heat exchange were noted initially and then the cool air is allowed to pass through the heat exchanger using the fan. the inlet and outlet temperature of air in the heat exchanger, along with pcm temperature in the selected modules are monitored continuously to study the heat transfer performance during the charging process. the experiments were continued until there is an appreciable drop in pcm temperature that ensured the complete solidification of the pcm. the discharging experiments were conducted followed by the charging experiments. air at a mass flow rate of kg/sec is allowed to pass through the heat exchanger and this air is entering the cabin. the experiments were commenced from . am in the morning until there is an appreciable increase in the temperature of the pcm that ensured the complete melting of the pcm. the air inlet temperature, outlet temperature, the pcm temperature and the temperature of the cabin at various rtd locations were monitored continuously. the measurements made at the inlet and outlet of the heat exchanger was used to evaluate the rate of heat transfer during the charging and discharging process. the instantaneous heat transfer (the rate at which the thermal energy is stored in the pcm) during the charging process is evaluated using equation ( ). qins = ma.ca (tout – tin) ( ) where, ma - mass flow rate of the air through the heat exchanger ca - specific heat of air qi tin - inlet temperature of the air tout - outlet temperature of the air the cumulative heat transfer qc is evaluated by integrating the instantaneous heat transfer qins considering the constant qins value prevails for every minutes duration. qc = dt ( ) where, dt - minutes ( seconds) qi - instantaneous heat transfer during i th time. n -number of time intervals iii. result and discussion figure shows the temperature variation of the pcm and the air temperature at the inlet and outlet of the modular heat exchanger. it is seen from the figure that the inlet temperature of the air is around ± . ºc. the pcm which is initially at ºc decrease at a faster rate up to . ºc and then the temperature drops at a very slow rate as the pcm releases latent heat and change its phase to solid state. the temperature of the pcm again starts decreasing at a faster rate around am in the morning. this decrease in temperature shows that the pcm in the modular heat exchanger is completely charged. during this charging process the temperature of the air at outlet start decreasing from ºc and after duration of minutes the temperature remains almost constant. the initial difference between the air inlet and outlet decreases gradually from to ºc. st international conference on new scientific creations in engineering and technology (icnscet- ) international journal of recent trends in engineering & research (ijrter) special issue; march - [issn: - ] @ijrter- , all rights reserved figure . temperature distribution during charging figure shows temperature variation of the pcm, ambient air and the temperature of the cabin where free cool air is circulated through the modular heat exchanger during the discharging process. it is seen from the figure that the ambient temperature varies from to ºc during the experiment; the ambient air during its passage through the modular heat exchanger is cooled by absorbing the cool energy from the pcm. the pcm in turn absorbs the heat energy from the air and start changing its phase to liquid state. the pcm temperature slowly changes from to ºc with in duration of four hours and then it starts increasing at a faster rate. the cabin temperature decrease from ºc and it reaches nearly ºc after a time interval of minutes. during this time the ambient temperature is around ºc and hence a maximum cooling of ºc is achieved inside the cabin after one hour from the start of experiment. this cooling potential of ºc is maintained for duration of another minutes and then the cooling potential decreases slowly. it is construed from the figure that the cool energy stored in the pcm is capable of decreasing the cabin temperature by ºc from the ambient temperature for a duration of approximately hours and then this cooling potential decreases slowly with respect to time. figure . temperature distribution during discharging iv. conclusion it is observed from the literature that there are few cities like bangalore and pune in india have large free cooling potential during the several months of the year. hence an attempt is made in the present investigation for the technical feasibility of free cooling at pune city by conducting experiments when the ambient conditions at chennai city matches well with the average ambient conditions that prevails during most of the months in pune st international conference on new scientific creations in engineering and technology (icnscet- ) international journal of recent trends in engineering & research (ijrter) special issue; march - [issn: - ] @ijrter- , all rights reserved city. it is understood from the various experiments that it is possible to enhance the cooling capacity further through free cooling integrated hybrid passive cooling concept which is presently under investigation. pcm r can be effectively used as energy storage mediums for free cooling applications. it has to be chosen wisely considering the heat load and the diurnal temperature variation of the place considered. the material and thickness of insulation provided have a vital role in this process. insulation has to be made in such a way that the energy has to be stored in the pcm without any loss for about - hours. references [ ]. adeelwaqas.,&ziauddin.( ). phase change material (pcm) storage for free cooling of buildings —a review.renewable & sustainable energy reviews. , – [ ]. belen zalba., jose m. marı́n., luisa f. cabeza., &haraldmehling.( ). free- cooling of buildings with phase change materials. international journal of refrigeration. , – . [ ]. medved, s., &arkar, c. ( ).correlation between the local climate and the free-cooling potential of latent heat storage.energy and buildings. , – . [ ]. osterman, e., tyagi, v.v., butala, v., rahim, n.a., &stritih, u. ( ). review of pcm based cooling technologies for buildings. energy and buildings. , – [ ]. pasupathy a. v,&velraj r. ( ). phase change material based thermal storage for energy conservation in building architecture. international energy journal. , – . [ ]. rajagopal m, solomon r.g, jayasudha k &velraj, r. ( ).free cooling potential and technology options for thermal energy management of a commercial building in bangalore city, india. energy engineering: journal of the association of energy engineers. , - . [ ]. saeedkamali. ( ). review of free cooling system using phase change material for building.energy and buildings. , – [ ]. prasath, k. arun, b. radha krishnan, and corresponding k. arun. "mechanical properties of woven fabric basalt/jute fibre reinforced polymer hybrid composites." int. j. mech. eng , no. ( ): - . [ ]. thambidurai m, krishnamohan n, rajagopal m, &velraj.r. ( ).free cooling feasibility of a typical commercial building in pune city, india. international journal of applied engineering research. , - . [ ]. thambidurai m., karthik p., krishna mohan n., velraj r. ( ). review on phase change material based free cooling of buildings-the way towards sustainability. journal of energy storage. , - . [ ]. waqas, a., & kumar, s. ( ). utilization of latent heat storage unit for comfort ventilation of buildings in hot and dry climates.international journal green energy. , – wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ stratigraphic model for distributary channels, 'j' and muddy sandstones, rocky mountain region: abstract; lithofacies variations in green river formation, wyoming: abstract association round table the sections are on the south flank of the uinta mountains, where measurements were taken. a total of measurements was made at t w o sections on the north flank of the uinta mountains. linear asym- metrical ripple marks were used exclusively because of their abundance at each section. analysis of the paleocurrent data indicates three major current directions during deposition of the moenkopi: northwest, southeast, and southwest. these are interpreted as representing wave-drift, rip, and longshore currents moving on and along a generally northeast-southwest-trending shoreline that bordered a shallow marine shelf during the early triassic. when the paleocurrent data of the north and south flanks of the uinta mountains are considered sepa- rately, the average northeast-southwest-trending shore- line of the south flank is interpreted t o shift t o a north- south trend on the north flank. this gradual shifting of the shoreline trend probably continued into wyoming where picard and high found a northwest-southeast trend in the moenkopi equivalent (red peak forma- tion) in west-central wyoming. the interpreted shore- line trend parallels the isopach trend of the moenkopi formation in northeastern utah. interpretation of shoreline trends leads to the evaluation of the depositional environments, current directions, and paleogeography during the time of deposition. economic interest in shoreline trend in- terpretation is high and will continue to be so in the future because of oil and gas exploration efforts. weimer, r. j., colorado school mines, golden, colo.; c. b. land, consultant, bismarck, n.d.; and l. t. macmillan, colorado school mines, golden, colo. stratigrapmc model for distributary channels, " j " and muddy sandstones, rocky mountain region no abstract available. wolfbauer, claudia a., u.s. geol. survey, denver, colo. lithofacies variations in green river formation, wyoming the green river formation of wyoming is a thick lens of sedimentary rocks which was deposited in a large playa-like complex. these sediments accumu- lated in three major depositional environments: ( ) marginal (ssiciclastic sandstone and siltstone); ( ) mudflat (marlstone); and ( ) lacustrine (oil shale, trona, fossiliferous limestone). in general, the basinward tran- sition of lithofacies is from coarse-grained, cross- bedded, channel sandstones at the bas|n margins to algal and oolitic limestones t o clastic a(id algal dolo- mitic marlstones and finally to oil shale' and trona at the center of the basin. the lateral int^rtonguing of these lithofacies and the repetition of large- and small-scale lithologic cycles provide a basis for the reconstruction of the physical, chemical, and biologic evolution of eocene lake gosiute. thin, but extensive, algal marlstone units reflect the basinward migration of lake gosiute's shoreline during periods of increased aridity. widespread fossil- iferous limestones suggest transgressive shoreline con- ditions. the occurrence of thin, extensive tuff beds establishes time-stratigraphic relations among the litho- facies. the correct interpretation of lithofacies changes in a closed basin can be an important tool for locating deposits of rich oil shale, trona, and perhaps oil- and gas-bearing channel sandstone reservoirs similar to those now being developed in the uinta basin. call for papers aapg th annual meeting april - , , dallas papers are being solicited for the aapg-sepm annual meeting april - , , in dallas, texas. any member of the aapg or sepm, or any other person sponsored by a member may submit a title and abstract for consideration by the program committee. by the time of the annual meeting, the energy "crisis" will have been with us for almost two years. how well win we have met this crisis? what are the prospects to alleviate it in the future? the meet- ing will review the status of our energy requirements, the political and socio-economic problems, and the technical aspects of meeting our needs. whereas the broad field of petroleum exploration and production is to be discussed, emphasis will be placed on problems concerned with making the united states more self- sufficient in meeting our energy needs. in keeping with this goal, papers are to be presented on ( ) new and immature potential areas in the united states, ( ) the search for pools smaller than the giants, ( ) the po- tential of secondary and tertiary recovery, and ( ) other sources of energy. the sepm technical program will include both special and general sessions on mineralogy, petrology, paleontology, stratigraphy, sedimentology, geochem- istry, and deep-water carbonates. "frontiers of exploration" is the general theme of the convention, but papers on any subject will be considered. please send tentative titles and write for abstract forms before august , . address requests for information to the appropriate program chairman: heniy c nelson, aapg technical program chairman, mobil research and development corporation, field research laboratory, p. o. box , dallas, texas ; chatles f . dodge, iii, sepm technical program chairman. department of geology, university of texas at arlington, arlington, texas . contributions to aapg foundation for month of december, michel t. halbouty speqal pubucations fund michel t. halbouty wallace pratt bulletin pubucation fund hollis d. hedberg hugh d. miser fund george d. glover george w. viele international journal of recent technology and engineering (ijrte) international journal of recent technology and engineering (ijrte) issn: - , volume- , issue- s , december published by: blue eyes intelligence engineering & sciences publication retrieval number: d s / ©beiesp doi: . /ijrte.d . s d s  abstract: the oily petroleum hydrocarbon discharge lead to the soil pollution, become harmful to both human being and the environment by long run. this present work is carried out systematically to evaluate the efficiency of brij- for washing used lubricant oil. for this study, the soil and waste engine oil which was collected from local service station are characterized. the soil under study was categorized through soil gradient test. the permeability of the soil was also determined. the soil fraction which was obtained by sieving through mm sieve was used for the present analysis. all the characteristic properties of the soil and oil were tested by a prescribed method. the used lube oil density was . gm/cc at c. the interfacial tension of the oil under study was . mn/m. this important finding helpful in finding the solution for soil contamination by improper disposal of oily hydrocarbon wastes like waste lube oil. keywords : soil remediation, waste oil treatment, mass percentage. i. introduction a. waste lube oil- the soil pollutant lubricating oil is the petroleum fraction which is used in almost all machineries and vehicles for decreasing rubbing between surfaces in moving parts. during its application, it undergoes oxidation and generated most impurities in base oil. this spent oil is known as waste engine oil. used lube oil (ulo) is the petroleum based synthetic spent oil and become unsuitable for its original purpose as it is subjected to high temperature and mechanical strain during running of the vehicle for stipulated time [ ]. it is a brown to black color liquid mixture consisting of low to high molecular weight(c - c ) aliphatic and aromatic hydrocarbons viz polychlorinated biphenyl, chloro dibenzofurans, alkylbenzenes, naphthalene, methylnaphthalenes, lubricative additives and decomposition products along with heavy metal contaminants such as zinc, antimony, iron, lead and chromium[ - ]. because of its structural stability, the degradation becomes challenge in such cases. revised manuscript received on december , . * correspondence author d.geetha*, chemistry, kalasalingam academy of research and education, krishnankoil, virudhunagar, india. email: geethachem @gmail.com m.s.revathy, physics, kalasalingam academy of research and education, krishnankoil, virudhunagar, india. email: revz.vijay@gmail.com gangadhara angajala, chemistry, kalasalingam academy of research and education, krishnankoil, virudhunagar, india. email: gangadharaangajala@gmail.com b.sundaravel, chemistry, kalasalingam academy of research and education, krishnankoil, virudhunagar, india. email: sundar.chem.bala@gmail.com thus, they are more dangerous anthropogenic pollutant and they have carcinogenic, less biodegradable mechanical impurities [ ]. used lubricant oil, causes environmental problem mainly due to the following reason [ ]:  source has no ineffective monitoring and control of their sources.  poor environmental monitoring of recycling. in some cases such as in passenger cars, the used oil was collected by the servicing companies whereas, in the case of agricultural machines like tractors the oil service need to be done on the spot. taking into consideration the fact that used oils are considered to be hazardous and extremely toxic waste, their transfer strategies viz. arrive filling, street oiling, dump on the ground diminishes soil efficiency for production of food and for age [ ]. b. trends of lube oil in india used lube oil is indeed harmful to the environment, but also has some recovery value. as per the hazardous waste (management, handling and transboundary movement) rules, (hw rules) any waste which by reason of any of its physical, chemical, reactive, toxic, flammable, explosive or corrosive characteristics causes danger or is likely to cause danger to health or environment, whether alone or when in contact with other wastes or substances are hazardous. as per schedule iv of the hazardous waste rules, , both used oil & waste oil have been categorized as ‘hazardous wastes’ and also listed in schedule i under the rules[ ]. fig. . quantum of recyclable waste generated in india [ ]. india has a huge recycling potential with a significant amount of recyclable waste generated. particularly, there are about spent oil (used/waste oil) registered recycling facilities distributed across districts spread over states in india with the total spent oil recycling capacity as . mmt [ ]. treatability of a used lube oil from contaminated soil geetha das, m.s.revathy, gangadhara angajala, b.sundaravel treatability of a used lube oil from contaminated soil published by: blue eyes intelligence engineering & sciences publication retrieval number: d s / ©beiesp doi: . /ijrte.d . s there is enormous potential in utilizing such wastes thereby conserving rapidly depleting natural resources, increasing employment, and reducing environmental degradation. the major constraint faced in recycling waste is cost of the collection, storage & subsequent transportation of the waste to the recycling unit. on the other hand, the development of bio lubricants facing constraints as they are . and times more expensive than conventional lubricants. in order to get the balance between economical and environmental balance, reprocessing of waste would be the best choice. hence there is huge scope for reprocessing of used/waste oil sector in india at present. fig. . lubricants trends in india [ , ] c. surfactant treatment on ulo the global trend is run after the green technologies in order to face the shortcomings of the top major environmental issues. numerous researches have been undergoing particularly for recycling the waste lube oil [ ]. various surfactants have been intensively studied for evaluating their efficiencies for the treatment of used lube oil [ , ]. the waste lube oil spillage into the soil contaminates and leads to the water pollution and in long run clog the aquifers and contaminate the ground water [ ]. the surfactant enhanced soil washing have already been used as an efficient technology for removal of soil contamination particularly with poly aromatic hydrocarbon (pah). d. background and objectives the rise of green economy and intensification of global energy crisis have been gaining attention of researchers and accelerating the research on recycling the waste oil in large scale. even though, small scale and pilot scale low technologies can not contribute much to the needed large scale high technology recycling, the joint efforts of various recycling technologies may bring forth alternate oil resources and reduction of environmental pollution as well. in this platform, the present study aims to know the efficiency of brij- surfactant solution in removing waste lube oil from contaminated soil. the collected soil sample was characterized by soil gradient analysis and specific gravity, permeability, bulk densities were measured. the density, viscosity and surface tension of the waste engine oil were also measured before the washing of the contaminated soil with surfactant. ii. materials and methods a. materials used lubricant oil collected from local auto mobile workshop nearby sivakasi, tamil nadu. soil under study was collected from kalasalingam university campus, krishnan koil, tamil nadu. the soil was artificially contaminated with waste engine oil. to simulate soil contamination by waste engine oil, the sandy material was first saturated with water and drained to residual water saturation, then restarted with oil and drained to residual oil saturation. the residual oil in the drained sand occupied approximately % of the soil pore space ( % saturation approximately . g per gram of soil) [ ]. n-hexane, commercial grade nonionic surfactant dodecyl alcohol ether (brij- ) was purchased from merck and used as received. b. methods for soil characterization  sieve analysis the fraction which was passing through a . mm sieve was used in the experiment after air drying. the soil sample which was collected is a medium to fine sand and categorized through soil gradient curve. the average hydraulic conductivity of the soil is × - cm/s. the physic-chemical properties are listed in table .  specific gravity the density bottle is washed with water and then washed with alcohol. finally, washed with ether to remove alcohol. weight of the empty bottle with stopper is (w ). about gm of soil sample which is cooled in desiccators is transferred to the bottle. w is the weight of the bottle and soil. ml of distilled water is put in the bottle and allowed the soil to soak completely. after hours again the bottle is completely filled with distilled water with stopper kept under constant temperature in water baths. the bottle is taken outside, dried, and weighed asw (the weight of the bottle and the contents). then empty bottle is cleaned thoroughly. that weight is w at temperature.  permeability test the permeability of soil was analyzed through constant head method as well as falling head method.  bulk density height of the cylindrical vessel in measured and then weight is taken. the vessel is filled with sand upto / height and again weighed. the sand is transferred to the mixing pan, % of water is added and mixed well. the most sand is transferred to the cylinder and the height is noted down from the top. with the increase of the percentage of water, the weight is noted down from the top till the height from the top is equal to the original height. the graph is drawn between the mixture content and percentage increase in bulk. b. methods for ulo characterization  viscosity of ulo the saybolt viscometer is used to determine the viscosity. the apparatus consists of an oil container surrounded by water container including stirrer and electric heater, underneath of collecting flask a valve cork provided to operate the capillary. two thermometers are fitted international journal of recent technology and engineering (ijrte) issn: - , volume- , issue- s , december published by: blue eyes intelligence engineering & sciences publication retrieval number: d s / ©beiesp doi: . /ijrte.d . s d s respectively in the oil and water container.  oil removal efficiency of the surfactant the aqueous solutions of brij- surfactant at various concentrations were used to wash the contaminated soil material, which had been contaminated with residual level of ulo. for these studies, g of contaminated soil was added to ml surfactant solution ( : solid to solution ratio) in a beaker and stirred on a magnetic stirrer for hours at c. the sample was allowed for settling. the supernatant solution was decanted after hours settling, and then the beaker with soil was first rinsed once with ml surfactant solution, and then twice with ml water. first rinse was to remove oil that became attached to the inside of the beaker during decanting of the supernatant and the second rinse with water were to wash the surfactant solution from the soil since it can interfere with the quantification of oil contaminant. the oil which remained on the soil was determined by the partition gravimetric using extraction methods [ ]. the contaminated soil was extracted with . ml of n-hexane and the extract filtered through a whatman filter paper then transferred into a petri dish. after evaporating n-hexane, the weight of the dish was taken and the amount of oil was quantified. iii. results and discussion a. soil characterization  sieve analysis by soil gradient the material that would have been retained on pan during sieve analysis is equal to the total mass of soil taken for dry sieve analysis minus the sum of the masses of material retained on all sieves. the graph was drawn and the grain size distribution curve for the soil in a semi-logarithmic graph is obtained and given in fig. and the results are tabulated in table- i. the specific gravity of the soil is . . the results of the permeability test are listed in table- ii & iii. the average permeability is calculated as follows: fig. . soil fraction obtained by soil gradient analysis. table- i. various soil fractions obtained by soil gradient analysis is.ieve no. wt retained in g.ms. cumulative wt retained cumulat ive wt retained % finer . mm . . . mm . . . mm . . mic . . mic . . mic . . pan . table- ii. results of permeability test by constant head method. height of water (h) time in sec (t) amount of water (a) . . . . . k = . cm/sec. table- iii. average permeability of the soil by falling head method. initial final time in sec permeability k * . . . . . * ]/al  bulk density bulk density is the weight of soil in a given volume. as per literatures, soils with a bulk density higher than . g/cm become more compact and restrict root growth. permeability is the ability of a soil to allow passage of water through the medium. understanding permeability gives an idea about the structure of the soil and how water passes through different layers. soil has a layered structure moreover water pressure at the surface would not be same at the middle portion. determination of permeability is an important one to study fluid-flow characteristics through a soil mass and thus helps in improving workability of the soil. the infiltration capacity of the soil will get reduced if its permeability and bulk density is higher. table iv. properties of the soil soil properties values texture medium to fine sand particle density . g/cm bulk density . g/cm ( . )* hydraulic conductivity × - cm/s ( * - )* treatability of a used lube oil from contaminated soil published by: blue eyes intelligence engineering & sciences publication retrieval number: d s / ©beiesp doi: . /ijrte.d . s ph - permeability(constant head method) . permeability (falling head method) . * values after contamination  characterization of ulo the density, viscosity and the interfacial tension (ift) of the oil under study have been considered as the very important fluid properties as they determine rate of product recovery and migration of oil. these properties were analyzed and given in table- iv. as per the results given in the table- iv, the waste engine oil has lower density i.e., . . thus the oil tends to accumulate above the water table region since its density is lower than that of the water. it is considered that, the density varies with temperature but as per the literatures, in most of the subsurface environments the temperature remains relatively constant. the viscosity and interfacial tension values of the oil give knowledge about the easiness of recovery. the oil with lower viscosity relatively has higher mobility than that of the thick oil of relatively higher viscosity. the interfacial tension of the oil determines the wettability of the oil. in general, higher the ift, higher is the capillary pressure and greater the stability of the interface, which is responsible for higher residual saturation. the interfacial tension for completely miscible liquids is dyne cm - and the surface tension of water is mn/m at °c[ ]. thus, the ift of the oil under study fall between these two extremes i.e., . mn/m. table- v: physico chemical properties of used lubricant oil test parameters test method results density ( ◦c) is part . gm/cc kinematic viscosity ( ◦c) is part . cst flash point (cleveland open- cup) is ) part ◦c water content is (instrument used – karl fisher titrator) . % (w/w) gross calorific value astm d . kcal/g ash content is part . % (w/w) lead as pb instrument used(icp-oes)-inductive coupled plasma optical emission spectrometer less than . mg/kg table- vi: viscosity variation with temperature. temperature of oil (c) time taken for ml collection (sec) kinematic viscosity (centistokes) absolu te viscosit y (ns/m ) . . . . . . the preferred surfactant concentrations for washing were fixed above its critical micelle concentration (cmc = . mm for brij ). the mass percentage of oil which was removed from the soil samples by surfactant washing are depicted in fig. . the washing ability of the surfactantincreased with increase of their concentration, thus increased solubility. as a result, the potential removal of trapped waste-lubricant oil droplets in the surfactant micelle gets increased. below cmc, the surfactant present as single molecule [ ]. after cmc, the surfactant molecule started to form micelles. the micelles solubilize more amount of waste engine oil by trapping them into its hydrophobiccore. fig. . change of viscosity with temperature.  batch washing of oil contaminant fig. . oil removal efficiency of brij- at various concentration ) . % ) % ) . % ) . % iv. summary and conclusion the global energy crisis is on high. the stringent environmental legislation led the industries to find the green alternates. in the present moment, the study of waste engine oil has become important, mainly contaminated soil remediation processes. the problem of soil and groundwater pollution was widely recognized in recent years. in this regard, determination of quality parameters of soil and waste engine oil maybe used as a vital need to uplift the quantum leap of used oil-recycling and understanding international journal of recent technology and engineering (ijrte) issn: - , volume- , issue- s , december published by: blue eyes intelligence engineering & sciences publication retrieval number: d s / ©beiesp doi: . /ijrte.d . s d s the soil remediation technology i.e. to remove waste lube oil from soil. this work will be useful in the identification of the extent of pollution of soil by the percolation of wastelube oil in long run. references . g grzegorz zajac, joanna sysiak-barklowic, tomasz siowik, andrzej kuranic, agnieszka kaminskaz, “original research designation of chosen heavy metals in used engine oils using the xrf method,” pol.j.environ.studies, vol. , , pp. – . . munna buttcharya,dipa biswasata, “a lab bench project for space craft autonomy enhancement of waste engine oil biodegradation by optimization of media using factorial design study,”indian journal of biotecnology,vol. , , pp. – . . arora k.r, “soil mechanics and foundation engineering”, th edition.,a.k.jain publishers, , pp. – . . a.j.t. bhandari, d.c. novakandand dove, “effect of soil washing on petroleum hydrocarbon distribution on sand surfaces,” journal of hazardous substance research, vol. , ,pp. – . . u.ghosh, j.s.gillette, r.g. luthy and r.n. zare, “microscale location, characterization and association of polycyclic aromatic hydrocarbons on harbor sediment particles,” environmental science and technology, vol. , , pp. – . . shan-tan lu andisaac r. kaplan, “characterization of motor lubricating oils and their oil–water partition,”journal environmental forensics, vol. , , pp. – . . riyanto , b.ramadhan, d.wiyanti,“treatment of waste lubricating oil by chemical andadsorption process usingbutanol and kaolin,” iop conf. series: materials science and engineering, vol. , , pp. . doi: . / - x/ / / . . jing, ye, zhang, yanli, “pour point depressant for waxy crude oil: a mini-review, recent innovations in chemical engineering formerly recent patents on chemical,vol. , , pp. – . . d.geetha, r.tyagi and n. kumar,“ability of sugar based glucoside surfactants for removal of petroleum contaminants,”journal of surface science and technology, vol. , , pp. – . authors profile d.geetha has completed m. sc in chemistry discipline from bharathidasan university, m. phil., from annamalai university. she completed ph. d from jaypee university in . she is currently working as an assistant professor at kalasalingam academy of research and education from onwards. her field of interest is bio surfactant. she has published papers in reputed international journals. m.s.revathy, has completed her ph.d in anna university in . she has done m.sc., m.phil physics in mother teresa women’s university, kodaikanal. currently working as assistant professor in department of physics, kalasalingam academy of research and education and her field of interests are thin films and green synthesis of nanomaterials. she has published papers in international journals. gangadhara angajala is working as an assistant professor in department of chemistry at kalasalingam academy of research and education. he completed his under-graduation in b.sc with triple major at government degree college for men, anantapur, andhra pradesh and his graduation with specialization in pharmaceutical chemistry at vellore institute of technology, tamil nadu. he obtained his ph.d with specialization in organic and medicinal chemistry from vellore institute of technology. his research area includes synthesis of new quinoline scaffolds with hypoglycemic efficacy by using nanocatalysis. b. sundaravel completed his masters degree at vhnsn college affiliated to madurai kamaraj university. he was awarded ph.d. degree in may by anna university, chennai, tamil nadu. currently he is working as an assistant professor at kalasalingam academy of research and education, krishnankoil, tamil nadu https://www.tandfonline.com/author/lu% c% bshan-tan https://www.tandfonline.com/author/kaplan% c% bisaac% br https://www.tandfonline.com/toc/uenf /current https://www.tandfonline.com/toc/uenf /current https://www.ingentaconnect.com/search% bjsessionid% d v spb ko.x-ic-live- ?option =author&amp;value =jing% c% bguolin https://www.ingentaconnect.com/search% bjsessionid% d v spb ko.x-ic-live- ?option =author&amp;value =jing% c% bguolin https://www.ingentaconnect.com/search% bjsessionid% d v spb ko.x-ic-live- ?option =author&amp;value =zhang% c% byanli https://www.ingentaconnect.com/content/ben/rice% bjsessionid% d v spb ko.x-ic-live- https://www.ingentaconnect.com/content/ben/rice% bjsessionid% d v spb ko.x-ic-live- adenosine and atp-sensitive potassium channels modulate dopamine release in the anoxic turtle (trachemys scripta) striatum adenosine and atp-sensitive potassium channels modulate dopamine release in the anoxic turtle (trachemys scripta) striatum sarah l. milton and peter l. lutz department of biological sciences, florida atlantic university, boca raton, florida submitted september ; accepted in final form february milton, sarah l., and peter l. lutz. adenosine and atp- sensitive potassium channels modulate dopamine release in the anoxic turtle (trachemys scripta) striatum. am j physiol regul integr comp physiol : r –r , . first published february , ; doi: . /ajpregu. . .—excessive dopamine (da) is known to cause hypoxic/ischemic damage to mammalian brain. the freshwater turtle trachemys scripta, however, maintains basal striatal da levels in anoxia. we investigated da balance during early anoxia when energy status in the turtle brain is compromised. the roles of atp-sensitive potassium (katp) channels and adenosine (ad) recep- tors were investigated as these factors affect da balance in mamma- lian neurons. striatal extracellular da was determined by microdi- alysis with hplc in the presence or absence of the specific da transport blocker gbr- , the katp blocker , -butanedione monoxime, or the nonspecific ad receptor blocker theophylline. we found that in contrast to long-term anoxia, blocking da reuptake did not significantly increase extracellular levels in -h anoxic turtles. low da levels in early anoxia were maintained instead by activation of katp channels and ad receptors. blocking katp resulted in a % increase in extracellular da in -h anoxic turtles but had no effect after h of anoxia. similarly, blocking ad receptors increased da during the first hour of anoxia but did not change da levels at -h anoxia. support for the role of katp channels in da balance comes from normoxic animals treated with katp opener; infusing diazoxide but not adenosine into the normoxic turtle striatum resulted in an immediate da decrease to % of basal values within . h. alter- native strategies to maintain low extracellular levels may prevent catastrophic da increases when intracellular energy is compromised while permitting the turtle to maintain a functional neuronal network during long-term anoxia. anoxia tolerance; microdialysis; theophylline; gbr- ; , -bu- tanedione monoxime unable to reduce its high energy requirements, the mamma- lian brain dies rapidly when deprived of oxygen ( ). the uncontrolled release of dopamine (da) into the extracellular space of the mammalian brain has been identified as one major cause of hypoxic/ischemic brain damage. although severe hypoxia or ischemia can increase extracellular levels as much as -fold ( ), even mild hypoxia (cortical arteriole po � torr) can cause neuronal damage, with da increases as high as % ( ). the increased extracellular da then con- tributes to neuronal damage by altering cerebral blood flow and glucose metabolism ( ), through the production of reactive oxygen species (ros) ( ), and by modulating the release of excitatory amino acids (eaas) ( ), especially through its interactions with glutamatergic systems ( , ). excess da has also been shown to inhibit the mitochondrial respiratory system, including complex i of the electron transport system ( ). unlike the widespread release of eaas, however, which occurs upon brain depolarization ( , ), da release is seen before high energy stores are fully depleted ( ), with santos et al. ( ) reporting a linear correlation between the ratio of atp to adp in synaptosomes and the release of da, although others have reported hypoxia-dependent decreases in atp that did not affect da release ( ). in the hypoxic mammalian brain, increases in extracellular da are due primarily to decreased reuptake into the cell ( , ), coupled with increased release from intracellular stores ( ). uptake back into the cell is the primary route of da removal from the extracellular space ( ), as is true of other neurotransmitters, and this occurs via an energy- and sodium- dependent specific transport mechanism ( , ). thus condi- tions that decrease energy availability in the hypoxic brain can induce increases in extracellular neurotransmitter levels well before energy stores are so depleted as to cause neuronal depolarization. a few vertebrate species, however, do not share the mam- malian central nervous system vulnerability to hypoxia and are in fact able to withstand months of complete anoxia ( ). the best-documented anoxia-tolerant vertebrate is the freshwater turtle trachemys scripta, which is able to maintain neuronal ion gradients and atp levels for at least h of anoxia at room temperature ( ) by lowering its metabolic rate to match glycolytic atp supply ( ) and thus avoiding anoxic depolar- ization and uncontrolled eaa release ( ). unlike mammals, the trachemys brain is also protected against increases in extracellular da even during complete anoxia; low da levels are maintained at least in part by the continued function of reuptake mechanisms ( ). the turtle brain is able to continue energy-dependent da reuptake be- cause, unlike the mammal, the anoxic turtle brain maintains atp levels during long-term anoxic conditions ( ). it is only when a significant imbalance occurs between energy supply and utilization that da increases above basal levels in the hypoxic or ischemic mammalian brain ( ). atp levels in t. scripta do drop significantly, however, during the first – h of anoxia when the turtle is in transition from normoxia to the depressed metabolism of complete an- oxia ( , ). during this temporary transition state, metabolic energy demands temporarily outstrip supply, and atp levels drop � %; after the turtle has completed metabolic suppres- sion, atp concentrations again rise to pre-anoxic levels ( ). although mammalian da homeostasis is lost during hypoxia, we have shown that striatal da in the trachemys brain remains at normoxic levels even during this transitional period ( ). address for reprint requests and other correspondence: s. l. milton, dept. of biological sciences, florida atlantic univ., glades rd., boca raton, fl (e-mail: smilton@fau.edu). the costs of publication of this article were defrayed in part by the payment of page charges. the article must therefore be hereby marked “advertisement” in accordance with u.s.c. section solely to indicate this fact. am j physiol regul integr comp physiol : r –r , . first published february , ; doi: . /ajpregu. . . - / $ . copyright © the american physiological societyhttp://www.ajpregu.org r downloaded from journals.physiology.org/journal/ajpregu at carnegie mellon univ ( . . . ) on april , . the question is thus raised, by what mechanisms(s) does the turtle brain maintain da balance in the extracellular space that is apparently insufficient or not utilized by the hypoxic mam- mal? two possibilities could explain the lack of increase in extracellular da when intracellular atp is reduced: da re- lease may occur along with a continued functioning of reuptake mechanisms (as occurs in long-term anoxia) despite decreased energy supplies, or the turtle may block the release of da, as it does with other excitotoxins such as glutamate ( ). one potential mechanism to prevent da release when atp is low is the activation of atp-sensitive potassium (katp) channels. these channels are normally inhibited by physiological levels of atp but open in response to de- creases in intracellular atp ( , ). these channels are thought to play a critical protective role during the early stages of ischemia in the mammalian brain ( ) by increas- ing membrane hyperpolarization, increasing cerebral blood flow ( ), and decreasing the release of excitatory neuro- transmitters including da ( , ). these mechanisms col- lectively reduce energy consumption while preventing de- polarization and thus provide a protective effect to the brain under conditions of low oxygen/reduced atp. as in the mammal, katp channel activation also protects the turtle brain against depolarization during anoxia. stimulated katp channels were shown by pek-scott and lutz ( ) to be involved in the downregulation of membrane ion (k�) perme- ability (channel arrest) during the first hour of anoxia in t. scripta. this protective effect could be blocked upon addition of katp channel blockers during the first hour of anoxia, but channel blockers had no effect by h of anoxia, consistent with a return to normoxic atp levels in the long-term anoxic turtle brain and closure of katp channels ( ). katp channels are also one mechanism by which the turtle brain decreases glu- tamate release during the first – h of anoxia, while stimula- tion of katp also decreases glutamate release in normoxic animals ( ). the known role of katp channels in preventing da release in the mammalian brain ( ) and their involvement in the anoxic tolerance of the turtle brain indicate a prospective mechanism to prevent da release into the turtle striatum during the initial energy crisis. along with katp, adenosine (ad) has also been shown to have protective effects in both the mammalian and turtle brain. ad r activation in the mammal inhibits neurons both pre- and postsynaptically by modulating ionic currents and decreasing neurotransmitter release ( , ); ad r activation decreases da release ( ), while antagonists increase daergic neuronal damage due to mitochondrial dysfunction ( ). in the anoxic turtle brain, ad acts as a “retaliatory metabolite” to balance energy supply and demand ( ) and increase cerebral blood flow ( ). as is seen with katp, stimulation of adenosine receptors (adr) in the normoxic and anoxic turtle brain also decreases glutamate release ( ), and adr stimulation is thus another prospective mechanism to prevent da release in early anoxia. the purpose of this study was to examine da balance during the transition period between normoxia and anoxia in the turtle brain and to determine whether activated katp channels and/or adr play a role in preventing extracellular da increases during this period. materials and methods materials. the studies described were approved by the institutional animal care and use committee of florida atlantic university. freshwater turtles (t. scripta) were purchased from a commercial supplier (lemberger, oshkosh, wi). the dopamine blocker -[ -[bis( -fluorophenyl)methoxy- ]ethyl]- -( -phenyl-propyl)piperazine dihydrochloride (gbr- ), katp channel blocker , -butanedione monoxime (bdm), and katp channel opener -chloro- -methyl- h- , , -benzothiadiazine , -dioxide (diazoxide) were purchased from tocris cookson (st. louis, mo). the specific k�atp channel blocker -chloro-n-[ -[ -[[[(cyclohexylamino)carbonyl]amin- o]sulfonyl]phenyl]ethyl]- -methoxybenzamide (glibenclamide) was pur- chased from research biochemicals international (natick, ma). all other chemicals and reagents were purchased from sigma chemicals (st. louis, mo), including ad and the general adr antagonist theophylline. methods. experiments were performed at °c on the freshwater turtles t. scripta elegans. animals were divided into groups (n � or per group): normoxic controls (no drug), normoxic experimen- tal animals treated with drug, early anoxia ( -h nitrogen exposure) treated with each drug, and long-term ( – h) anoxic animals treated with ad, the adr antagonist theophylline, or the specific da uptake blocker gbr- . drug treatments included: gbr- ( �m as per ref. ), the katp opener diazoxide ( �m as per ref. ), the katp blocker bdm ( �m as per ref. ), ad ( �m as per refs. , ) or the general adr blocker theophylline ( �m as per ref. ). bdm is a specific blocker of the katp channel able to reversibly inhibit whole cell katp currents with a ki � � mm for half-maximal inhibition and a hill coefficient of . � . ( ). data for anoxic control, normoxic, and -h anoxic turtles treated with gbr- have been previously reported ( ). additional control, -h anoxic, and -h anoxic animals (n � or per group) were treated with the katp channel blocker glibenclamide ( �m). all drugs were administered via the microdialysis probe perfusate in turtle artificial cerebrospinal fluid (acsf). turtles were anesthetized with aerrane (isoflurane, usp, anaquest) in air. anesthesia was induced using a % isoflurane in air mixture pumped from a . -l rebreathing bag. animals were main- tained on . % isoflurane once a surgical plane was achieved ( ). after exposing the skull, we trephined a -cm-diameter hole and removed the skullcap. a small incision through the dura mater exposed the cerebral hemispheres. a stereotaxic instrument and guide were used to insert a cma microdialysis probe ( mm membrane length; bioanalytical systems, acton, ma) into the striatum ( – mm depth from the cerebral surface, depending on animal size). the probe was perfused with turtle acsf solution at . �l/min with a cma/ microdialysis pump (carnegie medecin, solna, sweden); sam- pling was preceded by a -h stabilization period following probe insertion. previous work in our lab has demonstrated that h is a sufficient stabilization period to reduce extracellular neurotransmitters levels resulting from the damage of probe insertion. anoxia was induced by changing the breathing mixture to certified . % nitro- gen (county welding, pompano beach, fl) and . % isoflurane; previous studies have shown that arterial po is essentially zero by h of n ventilation ( ). dialysate was collected over -min intervals and analyzed imme- diately. baseline da levels were determined for all groups as the mean of the three samples ( . h) immediately before an experimental insult (drug or anoxia). drug control groups were sampled for an additional . h in normoxic animals with drug perfusion. for anoxic animals, turtles were ventilated on n following baseline sample for . h (short-term anoxic exposures) or . – . h (long-term anoxia) before drug insult. anoxic animals were then sampled for an addi- tional . h of drug/anoxic exposure. in all cases, perfusion with the experimental drugs in acsf was begun in the . -h sample before the time point of interest, to allow time for movement through the system’s dead spaces. probe recovery was determined from known r adenosine and katp channels modulate striatal dopamine ajp-regul integr comp physiol • vol • july • www.ajpregu.org downloaded from journals.physiology.org/journal/ajpregu at carnegie mellon univ ( . . . ) on april , . standards in vitro ( ). dopamine recovery averaged . � . % (mean � se); results presented are not corrected for recovery. samples ( �l) were analyzed for monoamine content using reversed-phase hplc with uv detection. the system consists of a waters hplc pump (waters, milford, ma), a rheodyne i manual injector (also waters), a . � -mm reversed-phase catecholamine column, (c , �m; obtained from alltech associ- ates, deerfield, il), and an spd- a uv spectrophotometric detector (shimadzu, kyoto, japan). the mobile phase flow rate was . ml/min and consisted of % mm potassium phosphate- % meoh. minimum detectable da levels with this method are � pg/ml. methylene blue was injected through the microdialysis probe at the end of each experiment to identify probe location; probes were rinsed following each use and reused up to a total of three times per probe. recovery decreases significantly if probes are utilized more than three times. data were used only from those turtles in which probe location in the striatum was verified. values are expressed as a percentage of baseline � se due to between-animal variability. statistical significance of changes was determined nonparametrically (kruskal-wallis test for unequal vari- ances utilizing the sas/jmp statistical package; cary, nc). in cases of equal variance, one-way anova/student’s t-test was used; p � . was considered to be statistically significant. results da reuptake ( h). during the first hour of anoxia, addition of the specific da uptake blocker gbr- into the turtle striatum did not result in any increases in extracellular da (fig. ); the turtle is apparently not releasing da into the extracellular space during the initial transition period. this is in direct contrast to both the normoxic and -h anoxic turtle, where addition of this uptake blocker increased extracellular striatal da two- to threefold ( ). katp channels. blocking katp channels with bdm in the -h anoxic turtle resulted in a significant increase in extracel- lular da, whereas this treatment had no effect after -h anoxia (fig. a). da levels in the dialysate ([da]dia) rose to a mean of � % of baseline after addition of the blocking agent during the initial hour of anoxia but changed � % compared with basal levels after -h anoxia. significant increases could be observed within . h of addition of the drug (fig. b). the increase in [da]dia seen at -h anoxia is not due to an effect of bdm alone, as addition of the blocker to the normoxic (con- trol) brain did not significantly alter [da]dia ( � % of basal levels). it thus appears that katp channels play a role in the turtle brain by preventing da release during the initial transi- tion period to anoxia, but this effect disappears during long- term anoxia. similar results were obtained using a second katp blocker; addition of glibenclamide increased [da]dia to a mean of � % of control in the -h anoxic turtle but had no effect in normoxic animals (not significant due to variability of time course, data not shown). further evidence that katp channels play a significant role in da balance in the turtle striatum was obtained with the katp activator diazoxide. perfusion of diazoxide into the normoxic brain resulted in an immediate significant decrease in extracellular striatal da, to � % of control values within . h (fig. ). fig. . extracellular dopamine in the striatum of the turtle does not change significantly over a -h anoxic exposure. administration of the specific dopamine (da) uptake blocker gbr- ( �m) does not increase extra- cellular da, indicating that da is not being released. mean da level in the dialysate ([da]dia) in the normoxic group was � �m. fig. . blocking atp-sensitive k� channels or adenosine receptors (adr) in the -h anoxia turtle resulted in significant increases in extracellular da. a: no increases occurred when the drug was administered to control [normoxia/ , - butanedione monoxime (bdm)] or -h anoxic animals. mean initial [da]dia in anoxic animals was � �m before drug administration; mean initial [da]dia was � �m in normoxic animals. *significant difference from control at p � . . b: typical time course of da increases in drug-treated animals. anoxia is initiated at the -h time point (left arrow); drug perfusion begins . h after the start of anoxia (right arrow). theo, theophylline. r adenosine and katp channels modulate striatal dopamine ajp-regul integr comp physiol • vol • july • www.ajpregu.org downloaded from journals.physiology.org/journal/ajpregu at carnegie mellon univ ( . . . ) on april , . adrs. blocking adr with the general adr blocker the- ophylline also significantly increased striatal [da]dia in the first hour of anoxia (fig. a) compared with untreated -h anoxic animals. [da]dia increased to a mean of � % of control vs. untreated striatal da levels of � % of basal; signif- icant increases were observed within . h of drug administra- tion (fig. b). da levels in untreated animals at - and -h anoxia were not significantly different from normoxic levels. as was observed with katp channels, at -h anoxia blocking adr with theophylline had no effect on extracellular da levels (fig. ). da in treated animals was � % of da in -h anoxic, untreated animals ( � %). in contrast to the dramatic effects of opening katp channels in normoxic animals, however, neither stimulating nor block- ing adr affected normoxic extracellular da (figs. and ). discussion this study demonstrates the critical roles played by katp channels and adr in depressing da release in the early anoxic turtle striatum. under normoxic conditions, homeostasis is maintained through continuous da release and reuptake, such that blocking reuptake results in significant da increases in the extracellular space ( ). blocking reuptake during the initial hour of anoxia, however, does not increase extracellular da levels (fig. ), indicating that release has been greatly reduced. this strategy differs from the long-term ( h) anoxic turtle, which remains in energy balance ( ) and is thus able to continue da release and reuptake ( ). the ability of the turtle to maintain low striatal da levels during anoxia is in direct contrast to the mammalian brain, where even mild hypoxia can increase da by %, and severe hypoxia/ischemia results in increases up to -fold ( , ); these large increases are closely correlated with atp depletion ( ). one mechanism that prevents da release during the initial transition phase of anoxia is the activation of katp channels. whereas the turtle remains in energy balance over long-term anoxia, there is a moderate decrease in atp levels in the turtle brain during the initial - to -h exposure ( ) that appears sufficient to stimulate katp channels and prevent da release. blocking katp channel activity more than doubled extracellu- lar da over the initial – h of anoxia (fig. ) but had no effect in the normoxic brain nor in the -h anoxic brain. in both the normoxic and long-term anoxic turtle, on the other hand, atp levels are high ( ) and katp channels are closed and thus unaffected by the blocking agent. further support for this hypothesis is demonstrated by the pharmacological activation of katp channels under normoxic (unstimulated) conditions, which caused an immediate decrease (within the first -min sample) in extracellular da. after . -h diazoxide perfusion, striatal da levels were only % of basal (fig. ). interest- ingly, although ad levels are known to affect both normoxic blood flow ( ) and glutamate release ( ) in t. scripta, neither the stimulation nor the blockade of ad receptors in normoxia affected extracellular da levels. adenosine, at �m, in the microdialysis perfusate has been shown to be sufficient to alter extracellular acetylcholine in rats ( ) and extracellular gluta- mate in the freshwater turtle ( ), thus we expect that any effects of normoxic ad exposure on extracellular da would have been revealed. however, the fact that diazoxide, but not ad, induces inhibition of normoxic da release is not surprising. as katp channels in many brain cells are normally closed ( ), they provide a straightforward functional switch between a closed, inactive state and the open, active state. adr, on the other hand, are functional during normoxia as well as during periods of metabolic stress; ad-dependent events are thus likely to have several layers of regulation that allow differential func- tions under varying metabolic states, including the opposing actions of a and a a type receptors on da release (see below). although the activation of katp channels in mammals has been demonstrated to extend anoxic/ischemic survival by hy- perpolarizing neuronal membranes and thus decreasing da and eaa release ( , ), these benefits are soon offset by the continued loss of k� that eventually results in cell depolariza- tion and excitotoxin release ( ). the cost to the turtle of maintaining open katp channels, however, is lower than in the mammal. katp channels are present in the trachemys brain at only – % of levels in the rat, in line with their overall reduced metabolic rate ( ), and the glibenclamide-inhibited population of katp channels are not a major route of k� loss in the turtle brain as they appear to be in some mammalian preparations ( ). in addition, other ion leak channels are inhibited in the anoxic turtle brain ( ); this channel arrest may decrease overall ion loss during anoxia to the point where any k� loss through katp channels can be offset by k� uptake mechanisms even under conditions of reduced atp produc- tion. k� loss upon ouabain depolarization is reduced vs. normoxia in the -h anoxic turtle brain whether katp channels are blocked or not ( ). unlike the mammalian brain, in fact, turtle neurons survive min of both anoxia and pharmaco- logical anoxia with no noticeable change in membrane resis- tance ( ). by contrast, rat pyramidal neurons respond to anoxia with a loss of membrane resistance, followed by a fig. . stimulation of atp-sensitive k� channels in the normoxic brain resulted in an immediate significant decrease in extracellular striatal da, which fell to � % of controls by . h. mean initial [da]dia was � �m before drug administration; diazoxide (dz) administration was begun immediately following initial sample. asignificantly different from control at p � . ; bsignificantly different from previous point, p � . . perfusing the normoxic turtle brain with adenosine (ad, �m) had no effect on striatal da release. mean initial [da]dia was � �m before drug administra- tion. r adenosine and katp channels modulate striatal dopamine ajp-regul integr comp physiol • vol • july • www.ajpregu.org downloaded from journals.physiology.org/journal/ajpregu at carnegie mellon univ ( . . . ) on april , . transient hyperpolarization and subsequent depolarization ( ). as purkinje cells of the isolated turtle cerebellum also do not hyperpolarize during anoxia ( ), the mechanism by which katp channels modulate da homeostasis is not likely to be via cellular hyperpolarization; however, an alternative method is yet unknown. research has suggested that katp channels may be modulated by a variety of signaling pathways, including neurotransmitter release, h o , and camp levels ( , ); it is quite possible then that katp channels, in turn, can act through second messenger systems directly, without cellular hyperpo- larization. the turtle may provide an interesting model to investigate such mechanisms, as in the mammal, the opening of katp channels is invariably associated with hyperpolariza- tion, and the possibility of more direct effects has not been examined. the decrease in cellular atp levels during the initial anoxic exposure, which opens striatal katp channels, results in turn in increased extracellular ad ( ) and the stimulation of adr. in addition, a direct link between a receptors and katp channels that appears critical for ischemic preconditioning has been suggested for the mammalian brain ( , ). as in the mam- mal, ad is a potent protective neuromodulator in the turtle, where ad increases increase cerebral blood flow ( ), modu- late channel arrest ( ), and decrease glutamate release ( ). but while it is necessary to block both katp channels and adr simultaneously to detect increases in glutamate in the – h anoxic turtle striatum ( ), blockade of either one individually increases da release. a similar link between increased ad during an energy crisis and decreased da release has also been reported in the rat brain, where the administration of an a agonist significantly decreases extracellular da ( ), while a antagonists increase da-related damage during mitochondrial dysfunction ( ). a receptors are also thought to have a tonic inhibitory effect in the rat nucleus acumbens to decrease both da and glutamate release ( ). although a a receptors appear to increase da and glutamate release ( , ), the inhibitory effects of a stimulation apparently outweigh the effects of a a receptors. conversely, it has been reported that the selec- tive blockade of da d receptors produces a significant in- crease in extracellular ad, presumably due to increased energy demands in dopaminergic cells ( ). the turtle brain, then, appears to use two different strategies to avoid increased extracellular da under anoxic conditions. during the initial energy crisis of anoxia, the turtle brain reacts in a manner similar to the hypoxic/ischemic mammal brain. katp channels and adr are activated by an initial decline in intracellular atp and consequent increase in extracellular ad, and these, in turn, prevent a catastrophic increase of da into the extracellular space by blocking its release during this period of energy crisis. during later anoxia, when atp levels have been restored, the turtle brain relies on da reuptake to maintain homeostasis. at this time katp channels and adr are no longer involved in da release, as katp channels have closed ( ) and extracel- lular ad levels are reduced ( ). unlike the mammal, however, the turtle brain is able to avoid depolarizing while downregulating metabolism to the hypometabolic state. upon return to basal atp levels in later anoxia, katp channels close ( ) while extracellular ad levels fall ( ); during such long-term anoxia, the turtle brain relies on da reuptake to maintain homeostasis. of course, it could also be that the anoxic turtle brain is simply unable to completely prevent da loss, and the -h transition period is too brief to observe any significant in- creases in extracellular da due to a decreased but still occur- ring da leakage from the cell. even stimulation of the katp channels during the transition period is not sufficient to com- pletely prevent da loss, as occurs in normoxic animals stim- ulated with diazoxide, as extracellular da remains at basal levels during this transition period. our previously reported continued reuptake over long-term anoxia, then ( ), would be an adaptation to prevent large da increases in the face of continuous, long-term loss. thus the apparent requirement to maintain low extracellular da levels may be for either or both of two reasons: protection against excessive da levels, which are likely to be toxic to the turtle brain, as in mammals ( ), and/or the maintenance of basal intra- and extracellular levels through continued long- term release and reuptake. the latter could be critical to maintain the neuronal circuitry of the long-term anoxic brain, as suggested by the continued low-level activity of other neuronal measures. the continued release and reuptake of glutamate also occur in the anoxic turtle brain, for example, despite an estimated energetic cost as high as . atp per glutamate ( ). the latter could be critical to maintain the neuronal circuitry of the long-term anoxic brain. the anoxic turtle brain also still exhibits frequent, periodic bursts of electrical activity despite being electrically quiescent overall ( ); we suggest that continued neuronal activity may be important for maintaining functional integrity in the metabol- ically depressed brain and allowing recovery when oxygen is again available. such continued energy expenditures, however, as well as the need to maintain ion gradients for gradient- dependent transport mechanisms, put a limit on the degree of ion channel arrest and metabolic reduction that can be achieved even over long-term anoxia. acknowledgments special thanks is given to robert delaney for technical assistance. grants partial support for this research was provided by the national science foundation and the florida atlantic university foundation. references . akiyama y, ito a, koshimura k, ohue t, yamagata s, miwa s, and kikuchi h. effects of transient forebrain 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acumbens. neurochem int : – , . . nilsson ge and lutz pl. release of inhibitory neurotransmitters in response to anoxia in turtle brain. am j physiol regul integr comp physiol : r –r , . . nilsson ge and lutz pl. adenosine release in the anoxic turtle brain: a possible mechanism for anoxic survival. j exp biol : – , . . pek m and lutz pl. role for adenosine in “channel arrest” in the anoxic turtle brain. j exp biol : – , . . pek-scott m and lutz pl. atp-sensitive k� channel activation provides transient protection to the anoxic turtle brain. am j physiol regul integr comp physiol : r –r , . . perez-pinzon ma, chan cy, rosenthal m, and sick tj. membrane and synaptic activity during anoxia in the isolated turtle cerebellum. am j physiol regul integr comp physiol : r –r , . . quarta d, ferre s, solinas m, you zb, hockmeyer j, popoli p, and goldberg sr. opposite modulatory roles for adenosine a and a a receptors on glutamate and dopamine release in the shell of the nucleus accumbens. effects of chronic caffeine exposure. j neurochem : – , . . remblier c, pontchamaud r, tallineaie c, piriou a, and huguat f. lactic acid induced increase of extracellular dopamine measured by microdialysis in rat striatum: evidence for glutamatergic and oxidative mechanisms. brain res : – , . . reshef a, sperling o, and zoref-shani e. opening of atp-sensitive potassium channels by cromakalim confers tolerance against chemical ischemia in rat neuronal cultures. neurosci lett : – , . . rothman sm and olney jw. glutamate and the pathophysiology of hypoxic-ischemic brain damage. ann neurol : – , . . santos ms, moreno aj, and carvalho ap. relationships between atp depletion membrane potential and the release of neurotransmitters in rat nerve terminals. an in vitro study under conditions that mimic anoxia, hypoglycemia, and ischemia. stroke : – , . . sciotti vm, roche fm, grabb mc, and van wylen dg. adenosine receptor blockade augments interstitial fluid levels of excitatory amino acids during cerebral ischemia. j cereb blood flow metab : – , . . shaw sl, leone-kabler s, lutz pl, and schulman a. isoflurane: a safe and effective anesthetic for marine and freshwater turtles. in: under our r adenosine and katp channels modulate striatal dopamine ajp-regul integr comp physiol • vol • july • www.ajpregu.org downloaded from journals.physiology.org/journal/ajpregu at carnegie mellon univ ( . . . ) on april , . wing; proceedings of the international wildlife rehabilitation council conference, edited by marshall b. madison, wi: omnipress, , p. – . . smith pa, williams ba, and ashcroft fm. block of atp-sensitive k� channels in isolated mouse pancreatic beta-cell by , -butanedione mon- oxime. br j pharmacol : – , . . tanaka t, yoshida m, kokoo h, mizoguchi k, and tanaka m. atp-sensitive k� channel openers block sulpiride-induced dopamine release in rat striatum. eur j pharmacol : – , . . tomiyama y, brian je jr, and todd mm. cerebral blood flow during hemodilution and hypoxia in rats: role of atp-sensitive potassium chan- nels. stroke : – , . . toner cc and stamford ja. effects of metabolic alterations on dopa- mine release in an in vitro model of neostriatal ischemia. brain res bull : – , . . wind t, prehn jh, peruche b, and krieglstein j. activation of atp-sensitive potassium channels decreases neuronal injury caused by chemical hypoxia. brain res : – , . r adenosine and katp channels modulate striatal dopamine ajp-regul integr comp physiol • vol • july • www.ajpregu.org downloaded from journals.physiology.org/journal/ajpregu at carnegie mellon univ ( . . . ) on april , . wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ editorial nanomaterials for electrochemical energy conversion and storage technologies suresh kannan balasingam , karthick sivalingam nallathambi , mohammed hussain abdul jabbar , ananthakumar ramadoss , sathish kumar kamaraj , and manab kundu department of materials science and engineering, norwegian university of science and technology (ntnu), trondheim , norway electrochemical materials and devices lab, department of chemistry, bharathiar university, coimbatore , india department of materials science and engineering, university of maryland, college park, maryland , usa laboratory for advanced research in polymeric materials (larpm), central institute of plastic engineering and technology (cipet), bhubaneshwar , india laboratory of the sustainable environment, technological institute of el llano aguascalientes (itel)/national technological institute of mexico (tecnm), aguascalientes c.p. , mexico department of chemistry, srm institute of science and technology, chennai , india correspondence should be addressed to suresh kannan balasingam; suresh.k.balasingam@ntnu.no received december ; accepted december ; published april copyright © suresh kannan balasingam et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. in this modern era, our society faces a serious energy crisis due to increasing human population. energy consumption starts from small-scale electronic gadgets to high power con- suming electric vehicles. to supply power on demand, researchers focus on alternative renewable energy resources including solar energy, wind energy, hydropower, geother- mal energy, and bioenergy. effectively, energy conversion and storage technologies such as solar cells, fuel cells, second- ary batteries, supercapacitors, and other self-powered sys- tems are under rigorous investigation. the efficient energy conversion and storage performance of those technologies rely on material properties of their electrode, electrolyte, and other device components. it is recently known that nanostructuring of device components leads to enhanced efficiency in terms of robustness and reliability of the energy conversion and storage systems. moreover, the nanostruc- tured materials have attracted great interest due to their unique physicochemical and electrochemical properties. hence, the utilization of such materials in nanodimensions will create enormous impact on the efficiency of various energy conversion and storage devices. the main objective of this special issues is to identify the significant research paradigms of nanomaterials and their potential impacts on applications. in particular, focus of this issue is on the syn- thesis and characterization of nanostructured materials for various applications such as supercapacitors, batteries, photoelectrochemical, and thermal enhancement systems. the highlights of the published articles are summarized as follows. in this special issue, y. yuan et al. synthesized the porous activated carbon materials from pleurotus eryngii-based biomass material via carbonization, followed by koh activation and utilized it for supercapacitor appli- cations. the as-prepared activated carbon presented a large specific area with high porosity which exhibited a maximum specific capacitance of f g- with % capacitance reten- tion after cycles. it is known that pleurotus eryngii is one of the readily available sources of carbon materials, potentially suitable for supercapacitor applications. also, this biomass can be the resource for development of porous acti- vated carbon for other energy conversion and storage devices hindawi journal of nanomaterials volume , article id , pages https://doi.org/ . / / http://orcid.org/ - - - http://orcid.org/ - - - http://orcid.org/ - - - http://orcid.org/ - - - http://orcid.org/ - - - http://orcid.org/ - - - https://creativecommons.org/licenses/by/ . / https://creativecommons.org/licenses/by/ . / https://doi.org/ . / / in the future. further, b.-x. zou et al. synthesized hierarchi- cal porous n, o-doped carbon composites by combining low molecular weight phenol resin and silk fibers in various com- binations using a hydrothermal method and carbonization process. the as-prepared electroactive materials showed a low resistance and good surface area with hierarchical poros- ity. the low molecular phenol resin and silk fiber combina- tion increases the surface area and enhanced the electron transport within the active materials. the fabricated symmet- ric device delivered a maximum energy density of . wh kg- and power density of . w kg− using aqueous electrolyte. l. t. n. huynh et al. prepared the lifepo @carbon com- posite material by hydrothermal method followed by thermal treatment for lithium-ion battery application. the different calcination processes did not affect the olivine structure; however, the surface morphology, the quality of carbon coat- ing, and the electrochemical properties were significantly changed. the sample annealed at °c showed a good spe- cific capacity of mah g- and the decent cyclic stability up to cycles due to an optimum amount of carbon coating over olivine material. in another lithium-ion battery article, p. m. nogales et al. developed a new method to estimate the ageing evaluation of li-ion batteries in a shorter time. the authors present the numerical analysis method using columbic efficiency and capacity loss rate that could deter- mine the cyclic stability of electrode material within a shorter evaluation time. y. liu and coworkers investigated the effect of surface defects density of zinc oxide films on the photoelectrochem- ical water splitting reaction. the surface defect density of zinc oxide photoanodes was tuned by annealing the electrodes at various temperatures. the surface photovoltage of zno films was obtained by kelvin probe force microscopy. the sample annealed at °c showed minimum surface photo- voltage, which confirmed that the low surface defect density sample showed enhancement in photoelectrochemical water oxidation. the applied bias photon-to-current efficiency of annealed zno photoanode reached to . %, about . times higher than that of unannealed zno photoanode. this work provided a potential method to design innovative photoanodes for photoelectrochemical water splitting. s. razvarz et al. performed the experimental research on thermal enhancement related to the heat pipe (with al o nanopowder) at different title angle. the important observa- tion is the increase in heat transfer coefficient with the increasing heat flux of the evaporator. while adding al o nanoparticles to pure water, the thermal efficiency of the heat pipe enhanced considerably. optimizing the quantity of the al o nanopowder assists in thermal efficiency enhance- ment. also, the heat pipe thermal efficiency enhanced with increasing nanoparticle concentrations and tilt angles. conflicts of interest we declare that there is no conflict of interests or private agreement with companies regarding our work for this special issue. we have no financial relationship through employment, consultancies, and either stock ownership or honoraria with industry. acknowledgments we would like to thank all the contributed authors and referees of this special issue, also grateful to the editorial board for the smoother process flow and rapid publication. the lead editor would like to thank all the editors for their time spent in reviewing and assigning reviewers for the sub- mitted manuscripts. suresh kannan balasingam karthick sivalingam nallathambi mohammed hussain abdul jabbar ananthakumar ramadoss sathish kumar kamaraj manab kundu journal of nanomaterials corrosion international journal of hindawi www.hindawi.com volume advances in materials science and engineering hindawi www.hindawi.com volume hindawi www.hindawi.com volume journal of chemistry analytical chemistry international journal of hindawi www.hindawi.com volume scienti�ca hindawi www.hindawi.com volume polymer science international journal of hindawi www.hindawi.com volume hindawi www.hindawi.com volume advances in condensed matter physics hindawi www.hindawi.com volume international journal of biomaterials hindawi www.hindawi.com journal of engineering volume applied chemistry journal of hindawi www.hindawi.com volume nanotechnology hindawi www.hindawi.com volume journal of hindawi www.hindawi.com volume high energy physics advances in hindawi publishing corporation http://www.hindawi.com volume hindawi www.hindawi.com the scientific world journal volume tribology advances in hindawi www.hindawi.com volume hindawi www.hindawi.com volume chemistry advances in hindawi www.hindawi.com volume advances in physical chemistry hindawi www.hindawi.com volume biomed research internationalmaterials journal of hindawi www.hindawi.com volume n a n o m a te ri a ls hindawi www.hindawi.com volume journal of nanomaterials submit your manuscripts at www.hindawi.com https://www.hindawi.com/journals/ijc/ https://www.hindawi.com/journals/amse/ https://www.hindawi.com/journals/jchem/ https://www.hindawi.com/journals/ijac/ https://www.hindawi.com/journals/scientifica/ https://www.hindawi.com/journals/ijps/ https://www.hindawi.com/journals/acmp/ https://www.hindawi.com/journals/ijbm/ https://www.hindawi.com/journals/je/ https://www.hindawi.com/journals/jac/ https://www.hindawi.com/journals/jnt/ https://www.hindawi.com/journals/ahep/ https://www.hindawi.com/journals/tswj/ https://www.hindawi.com/journals/at/ https://www.hindawi.com/journals/ac/ https://www.hindawi.com/journals/apc/ https://www.hindawi.com/journals/bmri/ https://www.hindawi.com/journals/jma/ https://www.hindawi.com/journals/jnm/ https://www.hindawi.com/ https://www.hindawi.com/ the cambridge university press has indicated that its production schedule will be delayed by the current british power crisis. its production staff is allowed to operate only three days per week and mails are running very slow because of a railroad strike. in fact the airmail letter in which ijmes was notified of this took three weeks to arrive in los angeles. copies of ijmes therefore will be delayed until the crisis has passed. cambridge university press and the editor will do everything possible to get the journal to you as soon as possible. call for papers and panels for the annual meeting the annual meeting of the association will be held in the statler-hilton hotel in boston, massachusetts, from november through , . ms. barbro ek of the middle eastern center at harvard university is handling the local arrangements. the program committee consists of professor paul ward english, center for middle eastern studies, university of texas, austin, texas, , coordinator, and james bill, university of texas, irene gendzier, boston university, and william hanaway, university of pennsylvania, members. professor charles adams of mcgill university has agreed to serve as carryover member. those wishing to submit suggestions for papers or for entire panels or symposia, or make any other suggestions concerning the content or format of the annual meeting, should communicate with professor english. those wishing to organize a panel or a symposium should think in terms of organizing from to people, and collecting titles and abstracts from them for submission to the program coordinator. those who wish to present a paper should submit a title and an abstract to the program coordinator. all this material should be in the hands of the program committee by april , . suggestions for the nominations committee the nominations committee charged with preparing the slates for the elections to mesa offices is chaired by professor j.c. hurewitz of columbia university. the other members are richard antoun of suny-binghamton, farhad kazemi of new york university and john masson smith of the university of california— berkeley. suggestions for nominations can be made to the chairman or to any other member of the committee, which will meet in the early spring. - - terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core a new international association—the world population society— was recently organized to encourage study of world population dynamics and its implications for the quality of life. the group will focus on the global aspects of population through an interdisciplinary approach. dr. cargille, the newly elected president, stated that the society will foster research and will publish scholarly works on pop- ulation problems, as well as sponsor regional and international meetings. among the society's objectives are the stimulation of international cooperation toward solution of population and environmental problems, the establishment of an information analysis center, the encouragement of disciplines to consider their relevance to population dynamics and the support of the teaching of population science. the society will also seek to promote recognition of population science as a discipline and to provide for public education and information. members will be solicited from numerous fields, includ- int the social, biomedical, management and information sciences. "global dialogue of the disciplines on population" was the theme of the first annual meeting held in washington, d.c. february - , . the meeting included sessions on the following: population and world human needs influencing population trends is there an optimum population? urbanization: positive and negative implications what are the feasible transitions from population growth to equilibrium? technological progress and cultural values population and sustainable standards of living: the world budget of proteins, energy and metals pollution — a possible mode of extinction? population, politics and social justice information about membership and society activities is available from dr. charles cargille, the world population society, the american university, washington, d.c. . ( ) - , ( ) - , or ( ) - . now available upon request are copies of frank joseph shulman's recently published bibliography american and british doctoral dissertations on israel and palestine in modern times. this work brings together for the first time postwar disser- tations dealing in whole or in part with the land of israel since the early 's. as such it encompasses doctoral research dealing with such subjects as palestine under the british mandate, the zionist movement in europe and the united states, the revival of hebrew as a modern language, and the communal settlements known as kibbutzim and moshavim, as well as the growth of the state of israel since , various aspects of the palestinian arab language and culture, developments on the west bank (jor- danian palestine) before and after june , and the continu- ing arab-israeli conflict. all disciplines of academic inter- est are included, and the theses are classified according to sub- ject and are listed within each section chronologically by date of acceptance. an author index as well as complete information on the best means for acquiring copies of the dissertations themselves are provided. for free copies of this bibliography, please write directly to: mrs. bonnie m. davis; xerox university microfilms, north zeeb road, ann arbor, michigan (usa). - - terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core robert m. lawrence and norman wengert, professors of political science, colorado state university, fort collins, have edited the november issue of the annals entitled "energy crisis: reality or myth?" single copies may be purchased by writing to the american academy at chestnut st., philadel- phia, pa. . nonmembers $ . ; members $ . . the following works have been published by cresm (centre de recherches et d'etudes sur les societes mediterraneennes): b. munier. la banque nationale pour le developpement economique et 'industrialisation du maroc. . m. flory, b. etienne, j.c. santucci, g. fouilloux. la succession d'etat en afrique du nord. . / a. adam. casablanca. essai sur la transformation de la societe marocaine au contact de 'occidents vol. ( e edition) . b. etienne. les proble'mes juridiques des minorites europeennes au maghreb, . a. cauneilie. l"es chaamba. leur nomadisme. evolution de la tribu durant 'administration francaise. . " j. couleau. la paysannerie marocaine. (epuise). ch. debbasch, r.p. sanson, r.p. lelong, n. sraieb, b. etienne,, j.p. colin, ch. souriau. mutations culturelles et coopera- tion au maghreb. . j.l. miege. documents d'histoire economique et sociale marocaine au xixe siecle. l w~. ch. souriau. la press maghrebine. ch. debbasch, t. leca, k~. remili, . marais, j. waterbury, a. khatibi, m. rousset, l. ben salem, a. zghal, r.e. germann. pouvolr et administration au maghreb. etudes sur les elites maghrebines. tt ch. debbasch, gt destanne de bernis, m. adam, p. valberg, j. poncet, j. ch. asselain, a..a. belal, a. agourram, ji. etienne, l. talha. les economies maghrebines. l'independence a l'epreuve du developpement economique, . y m. camau. /la notion de democratic dans la pensee des dirigeants maghrebins. r. le tourneau, a. benvoussef, b. etienne, n. sraieb, j.c. sanrucci, m. flory. l'unite maghrebine. dimensions et perspectives. . c. camilleri. jeunesse, famille et developpement. essai sur le changement socioculturel dans un pays du tiers monde (tunisie). ts t. m. teitler, a. nouschi, m. camau, b. etienne, n. sraieb, j.c. santucci j.j,. regnier, . marais, j. leca. elites, pouvoir et legitimitfe au maghreb. the first volume of humaniora islamica, the annual publica- tion for islamic studies and the humanities (published by mouton press, the hague), appeared in the fall, . it includes sec- tions on"north africa','"mediaeval islam,""turkish islam and other cultures,"and"the state of islamic studies. volume two of this work is due to appear fall and will include the following sections; "on history and anthropology in the study of islam," "early and mediaeval islam," "modern islam," and "reflections." for general information write: humaniora islamica, suite , boston university, bay state road, boston, u.s.a. the idoc (international documentation on the contemporary church) of north america, in collaboration with the arab-israeli research and relations project, recently published a new quarterly on the middle east.the special september issue was entitled "controversy in the middle east; u.n. resolution : an elusive hope for peace?" the subscription rate is $ . per year. for further information write: idoc-north america, east th st., n.y.,n.y. .( ) - . - - terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core the international labour office has published employment and income policies for iran. , priced at $ . "! for in- formation write: united states: ilo branch office, th floor, room , eleventh st., nw, washington, dc, ; canada: ilo branch office, rd floor, room , queen st., ottawa , ontario; united kingdom: ilo branch, sackville house, picca- dilly, london w v pa. the international publications service announces the publi- cation of two books: the th edition of who's who in lebanon, , p. cloth, price-$ . ; record of the arab world, yearbook of arab and israeli politics, volumes, c l, p., price $ . . for information write: international publications service, east nd street, new york, n.y. . vol. v, no. of iranian studies has recently been published and includes articles by h.j. rotblat, s.s. lieberman, book re- views by m.b. loraine, j.r. perry, r. taylor, and a directory of teachers of persian in the u.s. and canada compiled by m.a. jazayery. for information write: secretary of the society for iranian studies, p.o. box , village station, new york, n.y. , u.s.a. the tehran book processing centre of the institute for re- search and planning in science and education announces the publi- cation of the english edition of the iranian periodical directory, - , prices at $ . . send check or money order (include postage) to: tehran book processing centre (tebroc), p.o. box - , tehran, iran. haya gratch has recently edited twenty-five years of social research in israel, a review of the work of the israel institute of applied social research in the years - . the cost of the book is $ . . send all requests to: jerusalem academic press, p.o.b. , jerusalem, israel. the middle east research & information project has published the following reports: us and jordan: the thrice-rescued throne—the relationship between the us and the hashemite monarchy, and how and why tie us has bolstered it against nationalist jordanian and palestinian political pressures $ . socialist revolution in arabia: report from democratic yemen—a first-hand report on recent revolutionary develop- ments in the people's democratic republic of yemen $ . pakistan's role in us world strategy—a study of the inter- relationships among pakistan, iran and israel, with special focus on why the us supported west pakistan in the bangladesh war $ . retreat of the revolution in egypt—the political signifi- cance of developments in egypt through spring, ; notes from inside israel—a first-hand report on the life of the palestinians living under israeli occupation $ . iran: ten years after the "white revolution"—the politi- cal, social and economic roots of iran's present "economic miracle," and an explanation of iran's place in us global strategy $ . - - terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core student protests and the coming crisis in lebanon—how stu- dent protests are rooted in economic and political distor- tions caused by lebanon's dependence on western powers $ . middle east oil and energy crisis: part i — historical analysis of the us oil industry in the middle east to $ . middle east oil and the energy crisis: part ii—analysis of developments in middle east oil since and the oil company strategy behind the "energy crisis" campaign $ . the october war—a study of developments in egypt, syvia, and israel leading up to the war in october and prognostications for the future $ . us policy and the october war—an account of the rigidity of us policy from to october , and the new pres- sures forcing adaptation upon kissinger as a result of that war $ . for information write: merip, box , columbia heights station, washington, d;c; or merip, box , harvard square station, cambridge, mass. . the american institute of iranian studies announces the names of its new officers and executive committee: president professor t. cuyler young, jr. princeton university vice president professor rouhollah k. ramazani university of virginia secretary professor louis d. levine royal ontario museum treasurer mr. charles j. scheidt, jr. first national bank, chicago at-large professor robert h. dyson, jr. university of pennsylvania at-large professor william l. hanaway, jr. university of pennsylvania at-large professor emeritus t. cuyler young princeton university director of the tehran center dr. jerome w. clinton, a.i.i.s. address correspondance to: the president and the secretary: or the director of the tehran west asian department center: royal ontario museum kiaban moshtaq queen's park p.o. box - toronto, ontario tehran, iran canada m s c (telephone: ) (telephone: - - ) - - terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core the following were elected to the council of the society for iranian studies for : ervand abrahamian, baruch college, c.u.n.y. amin banani, university of california at los angeles james a. bill, university of texas at austin ali banuazizi, boston college jerome w. clinton, american institute of iranian studies gene r. garthwaite, dartmouth college paul w. english, university of texas at austin farhad kazemi, new york university kenneth a. luther, university of michigan ann schulz, clark university the turkish studies association announces the names of its officers for : president kemal h. karpat university of wisconsin at madison honorary president dankwart a. rustow brooklyn college, cuny graduate center secretary joseph s. szyliowicz university of denver treasurer sidney fisher (formerly of ohio state university) board of directors roderic davison george washington university ilhan bashgoz indiana university john smith university of california at berkeley richard chambers university of chicago the center for middle eastern studies, university of texas at austin, invites the submission of manuscripts based on scho- larly research in the field of middle eastern studies. such manu- scripts will be considered for publication in a series of books which the center is sponsoring in cooperation with the university of texas press. preference will be given to studies involving the late th and th centuries, with any disciplinary focus. inquiries and manuscripts should be addressed to the edi- torial board, center for middle eastern studies, university of texas at austin, austin, texas . - - terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core dr. taha hussein died in cairo on october , , at the age of eighty-four. he had received the united nations human rights prize the day before. a memorial tribute was read at the annual meeting of the middle east studies asso- ciation in milwaukee by prof. roger allen of the university of pennsylvania. an obituary appears in the october , edition of the new york times. dr. otha l. clark, a fellow of the association, died in october at the age of sixty-six. - - terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core 	s .pdf 	s .pdf historical note photovoltaic materials during the worldwide energy crisis in the s, researchers focused enormous effort toward developing new energy sources, including "clean and inexhaust- ible" solar power. unlike electric genera- tors, solar cells have no moving parts, thus eliminating one common wear mecha- nism. and unlike batteries or fuel cells, so- lar cells produce no pollution from using chemical reactions to produce power. small solar cells placed into arrays can be used to generate power in remote loca- tions, such as for water pumps in the deep desert, navigational beacon buoys at sea, and satellites in space. thousands of cells can work together as central electric power stations, or smaller arrays can power hand calculators and portable telephones. they can operate almost indefinitely if protected from damage. the concepts and crude prototypes for solar power have been around for about a century and a half. the theory behind so- lar cells was first touched on in by the physicist becquerel in france. becquerel experimented with a solid electrode im- mersed in an electrolyte solution, observ- ing that a voltage developed when light fell upon the electrode. this is called the pho- tovoltaic effect. in heinrich rudolf hertz, a physi- cist in germany, discovered the photoelec- tric effect. hertz observed that ultraviolet light could facilitate a spark across an air gap between metallic electrodes. it wasn't until that joseph j. thomson (discov- erer of the electron) and philipp edward anton lenard determined that light was causing the emission of electrons from the surface of a material. by , lenard had also shown that the number of electrons emitted per second from a photoelectric material was proportional to the intensity of the incident light, but that the energy of those electrons depended on the wave- length of the incident light. this result was puzzling and incomprehensible to the clas- sical physics community at the time, and was not resolved until , when albert einstein proposed a quantum theory on the dual nature of light. it was primarily for this work that einstein won the nobel prize in . working from the -year-old theories of becquerel, charles fritts constructed the first actual solar cell in by coating the semiconductor selenium with an ex- tremely thin layer of gold. though fritts' prototype cells succeeded in converting only % of the incident sunlight into elec- tricity, they fostered visions of clean and inexhaustible power (which must have seemed very desirable in the dirty, early days of the industrial revolution). two years after fritts created his first cell, r. ap- pleyard wrote excitedly of "the blessed vi- sion of the sun, no longer pouring his energies unrequited into space, but by means of photoelectric cells... gathered into electrical storehouses to the total extinction of steam engines and the utter repression of smoke." also in , julius elster and hans ger- tel published the first of a long series of papers on photoelectricity. they showed that when certain metals (including potas- sium, sodium, zinc, and aluminum) were amalgamated with mercury, they became photoelectrically sensitive not only to the ultraviolet light hertz had used, but also to visible light—which meant the effect was caused by simple sunlight. a plate of zinc in air at atmospheric pressure could ac- quire a potential difference of up to . volts. elster and gertel also showed that other metals—tin, copper, and i r o n - remained inactive. the following year they designed the forerunner of a modern photoelectric cell, an evacuated glass bulb containing alkali metals or their alloys or amalgams. with an external battery to provide a positive po- tential, this cell produced an electric cur- rent when illuminated by visible light. in , they used a device operating on the same principle as the first photoelectric photometer, measuring ultraviolet radia- tion from the sun. by a metal-semiconductor-junction solar cell had been made of copper and copper oxide. in and , b. lange and l. bergman, respectively, discovered the photoelectric effect in selenium barrier- layer cells. actually, this work had already been done in by w.g. adams and r.e. day, but went unnoticed. in the dec- ade of the s, lange as well as l.o. grendahl in the united states and walter schottky in switzerland conducted de- tailed studies of selenium and cuprous ox- ide photovoltaic cells. both types of cells were used in light-sensitive devices, al- though their conversion efficiencies still rarely exceeded %. a breakthrough finally occurred in , when russell ohl proposed using silicon for a photovoltaic cell. not until years later, however, did an engineer—paul rap- paport in america—conceive of using sili- con photovoltaic cells as relatively efficient power sources. later in , daryl m. chapin, g.l. pearson, and calvin fuller demonstrated a functioning silicon solar cell capable of % energy conversion effi- ciency when used in direct sunlight. silicon is now the most commonly used semiconductor material for photovoltaic cells. this material is useful at wavelengths less than , nm, which is the visible and near-infrared region of the spectrum. while selenium and copper-oxide photo- voltaic cells use a semitransparent metallic film of gold or platinum deposited on the semiconductor surface to create the neces- sary potential barrier, silicon solar cells use the p-n junctions within two adjacent lay- ers of silicon; the layers of silicon are doped with impurities of arsenic or boron to cre- ate electrons and holes that generate a po- tential difference. such semiconductor cells can be ex- tremely thin, about a millimeter or less. however, the power generated depends on the total surface area illuminated by sunlight. current manufacturing tech- niques make silicon solar cells about cm wide by cm long, but power arrays can contain as many as , individual cells. until the early s, silicon solar cells such as the bell battery functioned at up to % efficiency and could produce a current of about ma/cm . bell solar batteries were put to use as power sources on satel- lites. in the s, a great many semiconduct- ing materials were used in effective photo- voltaic cells, including gallium arsenide, indium phosphide, copper indium se- lenide, cadmium sulfide, and cadmium telluride. efficiencies with some of these materials reached % when used in direct sunlight. in a "concentrator solar cell," which uses lenses to concentrate sun- light onto the cell surface, reached an effi- ciency of %. solar cells are now frequently used in specialized applications such as toys, cal- culators, portable phones, and radios, where power needs are usually less than a kilowatt. widespread application of solar cells has been hindered by their cost—solar electricity still costs about to , times as much as conventionally generated elec- tricity. and because their peak efficiencies are possible only during days of total sun- light, solar cells are impractical in cloudy climates. new materials, improved fabrica- tion techniques, and more efficient solar cell designs, however, are bringing the cost down and making solar cells more feasible. kevin j. anderson mrs bulletin/june https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core ia a ae s t annual meeting preliminary program general chairman: gaylord p. harnwell (president emeritus, university of pennsylvania) aaas invited lectures and panels * special lecture ( dec.). constantinos a. doxiadis (president, athens techno- logical organization, athens, greece). * distinguished lecture ( dec.). loulis s. b. leakey (director, center for prehistory and palaeontology, national museum, nairobi, kenya). * address of the retiring aaas president ( dec.). athelstan spilhaus (fellow, woodrow wilson interna- tional center for scholars, smithsonian institution). * resa annual address and panel discussion ( dec.). jack e. goldman (senior vice prosident, research and development, xerox corporation, stamford). * phi beta kappa lecture ( dec.). jean mayer (professor, harvard university school of public health). special lecture ii ( dec.). charles eames (designer, venice, calif.). * illustrated lectures ( - dec.). carl sagan (professor, center for radiophysics and space research, cornell university) ( dec.). alvin m. weinberg (director, oak ridge national laboratory) ( dec.). paul d. maclean (director, brain evolution and be- havior laboratory, national institute of mental health) ( dec.). jerome s. bruner (professor of psychology, harvard university) ( dec.). william j. l. sladen (professor, the johns hopkins uni- versity school of hygiene and public health) ( dec.). physical universe * acoustics of orchestral musical instruments ( dec.). arranged by arthur benade (case western reserve uni- versity). [part of a symposium on sound and music] * architectural acoustics ( dec.). arranged by r. s. shankland (case western reserve university). [part of a symposium on sound and music] * contributions of operations research to mathematics ( dec.). arranged by saul i. gass (mathematica, inc., bethesda, md.). october * lightning ( dec.). arranged by richard e. orville (nsf). * astronomy from a space platform ( - dec.). arranged by g. w. morgenthaler (martin marietta cor- poration, denver). * the early history of the earth and moon ( dec.). arranged by s. fred singer (university of virginia). * oceanography-its status today and outlook for the future ( - dec.). arranged by harris b. stewart, jr. (noaa atlantic oceanographic and meteorological laboratories. miarmi). * the cosmic distance scale ( dec.). arranged by l. w. fredrick (university of virginia). living world * biologic relativity ( dec.). arranged by e. r. n. grigg (chicago medical school). * some mathematical questions in biology ( - dec.). arranged by jack d. cowan (university of chicago). * the role of odor in life activities ( dec.). arranged by irvin hornstein (aid). * chromosomal analysis and differentiation ( dec.). arranged by hans laufer (university of connecticut). * arthropod molting ( dec.). arranged by john d. o'connor (university of california, los angeles). * the vertebrate integument ( - dec.). arranged by paul f. a. maderson (brooklyn college). * physics looks at biological structure ( dec.). arranged by britton chance (university of pennsyl- vania). * george sarton memorial lecture ( dec.). from catastrophism to evolutionism-the history of a conceptual transition, by ernst mayr (harvard uni- versity). * research in the national parks (centennial sympo- sium commemorating the founding of the national park service, ) ( - dec.). philadelphia, pennsylvania - december o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ arranged by robert m. linn (national park service, washington, d.c.). * mineral elements in the food chain ( - dec.). arranged by michael a. farrell (state college, pa.) and matthias stelly (american society of agronomy). * living systems: synthesis, assembly, origins ( dec.). arranged by sidney fox (university of miami). * recent advances in pollination biology: quantifica- tion and case studies ( dec.). arranged by herbert g. baker (university of california, berkeley). * polar deserts ( - dec.). arranged by terah l. smiley and james h. zumberge (university of arizona). * cave biology of bats: their ecology, physiology, behavior, and future survival ( dec.). arranged by robert e. henshaw (pennsylvania state university). * the formation of diploid neospecies ( dec.). arranged by hampton l. carson (university of hawaii). health, disease, behavior * the role of aggression in human adaptation ( dec.). arranged by jacob a. arlow (state university of new york, new york city). * urban health care ( dec.). arranged by alfred gellhorn (university of pennsyl- vania). [part of a symposium on the sciences in the service of urban philadelphia] * aaas vice presidential address (anthropology), and population control in social and economic perspec- tive ( dec.). given and arranged by ward goodenough (university of pennsylvania). * human response to environmental stimulation: from the laboratory to the field ( dec.). arranged by joachim f. wohlwill (pennsylvania state university). * articulation phenomena and disorders ( dec.). arranged by ralph shelton (university of arizona). * confronting the violence of normal man ( dec.). arranged by israel w. charny (group for research in the psychology of aggression and nonviolence, paoli, pa.). * scientific aspects of contraception ( dec.). arranged by george b. koelle (university of pennsyl- vania). * aaas vice presidential address (pharmaceutical sciences) ( dec.). the role of the hospital pharmacist and the pharm. d. -a problem in curriculum development, by wallace l. guess (university of texas, austin). * distinguished lecture of the aaas section on phar- maceutical sciences ( dec.). human variability and safer, more effective pharmaco- therapy, by george j. cosmides (national institute of general medical sciences). * invertebrate behavior ( - dec.). arranged by peter n. witt (north carolina department of mental health). * musical perception ( dec.). arranged by w. dixon ward (university of minnesota). [part of a symposium on sound and music] * comparative aspects of ovarian function and con- trol ( dec.). arranged by ian p. callard (boston university). * biological and cultural bases of sex role differentia. tion ( dec.). arranged by alexander alland, jr. (columbia univer- sity) and adrienne zihiman (university of california, santa cruz). * on the relations between basic research and appli- cations of psychology ( dec.). arranged by james j. jenkins (university of minnesota). * the over-medicated society ( dec.). arranged by m. c. smith (university of mississippi). * smoking and health now ( dec.). arranged by abraham m. lilienfeld (the johns hopkins university). * data from eeg and other areas of parapsychology ( dec.). arranged by e. douglas dean (newark college of engineering). * comparative immunology of the oral cavity ( - dec.). arranged by henry w. scherp (national institute of dental research). * thirst: new findings and advances in concepts ( - dec.). arranged by alan n. epstein and eliot stellar (univer- sity of pennsylvania). * prenatal ontogeny of behavior and the nervous system ( - dec.). arranged by gilbert gottlieb (north carolina depart- ment of mental health). * differences in viewpoint: the drug addict and his physician ( dec.). arranged by john c. ball (temple university). * how valuable is human health? ( dec.). arranged by edmund d. pellegrino (state university of new york, stony brook) and ronald w. mcneur (so- ciety for health and human values, philadelphia). science, vol. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ * regulation of organ and tissue growth ( - dec.). arranged by richard j. goss (brown university). * sentics, brain function, and sources of human values ( - dec.). arranged by manfred clynes (rockland state hospital, orangeburg, n.y.). * heavy metals as an environmental hazard to fish, birds, and man ( dec.). arranged by gerald j. lauer (new york university). * encounter groups ( dec.). arranged by kurt w. back (duke university). * studies in sexuality ( dec.). arranged by leo madow (medical college of pennsyl- vania). environmental problems and urban affairs * university-black ghetto relations: a case study ( dec.). arranged by russell l. ackoff (university of pennsyl- vania). [part of a symposium, on the sciences in the service of urban philadelphia] * environmental education workshop and seminar ( dec.). arranged by robert e. samples, manert kennedy, and nicholas helburn (university of colorado). * experimental manipulation of natural systems ( dec.). arranged by william e. cooper (michigan state univer- sity). * the role of state and local academies in providing information concerning environmental education ( dec.). arranged by wilmer w. tanner (brigham young university). * academies and environmental education ( dec.). arranged by wilmer w. tanner. * indicators of environmental quality ( - dec.). arranged by william a. thomas (oak ridge national laboratory). * nature study for impact and action ( - dec.). arranged by kingsley l. greene (state university of new york, morrisville). * environmental sciences and international develop- ment ( - dec.). arranged by m. taghi farvar, michael w. corr, and alan h. mcgowan (washington university). * general systems of the world environment ( - dec.). arranged by philip c. nunn (center for environmental studies, grand rapids, mich.) and richard f. ericson (george washington university). october iaialalsi annual meeting * new towns and old cities: prospects for partnership in urban planning ( dec.). arranged by william l. rafsky (greater philadelphia movement). [part of a symposium on the sciences in the service of urban philadelphia] * city life ( dec.). arranged by john szwed (university of pennsylvania). * alternative approaches to national delivery of health care ( dec.). arranged by george k. chacko (institute of aerospace safety and management, washington, d.c.). * student-originated studies: an ongoing experiment in undergraduate student-directed studies of en- vironmental problems ( - dec.). arranged by alexander j. barton and charles h. dickens (national science foundation). * interactions between natural and urban ecological communities ( dec.). arranged by ruth patrick (academy of natural sci- ences). [part of a symposium on the sciences in the service of urban philadelphia] * environmental noise and its control ( dec.). arranged by r. l. bannister (westinghouse electric corporation). [part of a symposium on sound and music] * geological implications of solid waste landfill ( dec.). arranged by arthur a. socolow (pennsylvania geologi- cal survey, harrisburg). * the future of the cities: an overview panel discus- sion ( dec.). arranged by david r. goddard (university of pennsyl- vania). [part of a symposium on the sciences in the service of urban philadelphia] technology * energy production from nuclear fusion ( dec.). arranged by roy gould (u.s. atomic energy commis- sion). * technology and the humanization of work ( dec.). arranged by michael maccoby (institute for policy studies, washington, d.c.) and neal q. herrick (u.s. department of labor). * practical solutions to metric conversion ( dec.). arranged by edward a. munns (myrtle beach, s.c.). * radical approaches to ecology ( dec.). arranged by garland allen (washington university). * engineering-for the survival of man ( dec.). arranged by t. todd reboul (rca corporation, moorestown, n.j.). o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ * the energy crisis: some implications and alternatives ( - dec.). arranged by dean abrahamson (university of minne- sota). * man-machine interactions and implications for so- ciety ( dec.). arranged by carl l. sandler (battelle memorial institute, seattle). * communications technology and its effect on people ( dec.). arranged by walter baer (rand corp., santa monica). * social control of science and technology ( dec.). arranged by michael baram (massachusetts institute of technology). * the navigation sciences ( dec.). arranged by c. towner french (p. r. mallory & co., inc., washington, d.c.) and raynor l. duncombe (u.s. naval observatory). social, political, economic interactions * educational finances and revenue sharing ( dec.). arranged by janos horvath (columbia university). * religious intermarriage ( dec.). arranged by john e. hughes (villanova university). * employment and utilization of scientists ( dec.). arranged by h. william koch (american institute of physics). * scientific institutions of the future ( dec.). arranged by philip c. ritterbush (organization: :re- sponse, washington, d.c.). * fair hiring practices ( dec.). arranged by harvey m. sapolsky (university of michi- gan). * interreligious conflict in northern ireland ( dec.). arranged by john e. hughes. * operations research and management science in the administration of justice ( - dec.). arranged by carl m. harris (george washington uni- versity) and alfred blumstein (carnegie-mellon uni- versity). * the use of scientific information in policy-making ( dec.). arranged by richard h. bolt (bolt beranek & newman, inc., cambridge). * science and medicine in the peoples republic of china: contemporary observations ( dec.). arranged by robert j. rutman (university of pennsyl- vania). * population trends in nonmetropolitan areas: re- search and policy ( dec.). arranged by gordon de jong (pennsylvania state uni- versity). * organizing quantitative data for svientific applica- tion: issues faced by the president's commission on federal statistics ( dec.). arranged by morris b. ullman (bethesda, md.) and daniel rathbun (president's commission on federal statistics). * crucial transitions in civilization: a problem in macrocultural interpretation ( dec.). arranged by roger w. wescott (drew university). * aaas vice presidential address (social and economic sciences) ( dec.). waste disposal in an age of rubbish: social science interpretations of american society in the 's, by daniel p. moynihan (harvard university). * the changing american population: the social and economic implications of the census and other national surveys ( dec.). arranged by harvey m. sapolsky. * the new radicalism in science ( dec.). arranged by david nichols (case western reserve university). * federal policy goals and r & d programs: where they mesh and where they don't ( dec.). arranged by juergen schmandt (university of texas, austin). * aaas vice presidential address (statistics) ( dec.). how does one measure discrimination against women?, by elizabeth scott (university of california, berkeley). * can we develop an index for quality of life? ( dec.). arranged by s. fred singer (university of virginia). * women in academia: evolving policies toward equal opportunities ( dec.). arranged by arie y. lewin (new york university). * congress and future trends in american politics ( dec.). arranged by robert puckett (indiana state university). * new conceptual frameworks for science and public policy studies ( dec.). arranged by harvey m. sapolsky. * the older family and bureaucracy ( dec.). arranged by gordon f. streib (cornell university). ethics, philosophy, history * problems in th century american science ( dec.). arranged by charles a. culotta (bryn mawr college). * science, technology, and medicine in philadelphia, - ( dec.). arranged by w. b. bell, jr. (american philosophical society). science, vol. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ * value and knowledge requirements for peace ( - dec.). arranged by vincent p. rock (national research coun- cil). * "the descent of man"-charles darwin, : a review of a century of progress in understanding man's origins ( dec.). arranged by elwyn simons (yale university). * th anniversary of the birth of johannes kepler ( dec.). arranged by raymond j. seeger (aaas, washington, d.c.). * teaching the history and philosophy of science in science courses ( dec.). arranged by raymond j. seeger. * the role of mathematics in the development of science ( dec.). arranged by raymond j. seeger. * looting the past: an international scandal ( dec.). arranged by richard i. ford (university of michigan). * nonlinear research in the sciences and humanities ( - dec.). arranged by michael kosok (fairleigh dickinson uni- versity). * youth speaks about itself ( dec.) arranged by ruth s. freed (seton hall university) and stephanie miller (new york university). education, learning, communication * the graduate student ( dec.). arranged by hazel fox (university of nebraska). * humor in science ( dec.). arranged by james v. mcconnell (university of michi- gan). * the information conscious society ( dec.). arranged by eugene garfield and morton v. malin (institute for scientific information, philadelphia). * science writing as literature ( dec.). arranged by eugene h. kone (rockefeller university). * science and the humanities ( - dec.). arranged by frederick d. horn (westminster college). * socially responsive actions by institutions of higher education ( dec.). arranged by millard e. gladfelter (temple university). [part of a symposium on the sciences in the service of urban philadelphia] * urban education in the schools ( dec.). arranged by ezra staples (philadelphia board of public education). [part of a symposium on the sciences in the service of urban philadelphia] october iaiaiaisi annual meeting * the relation between applications of mathematics and teaching of mathematics ( dec.). arranged by henry . pollak (bell telephone labora- tories). * the cerebral librarian: functions and malfunctions ( dec.). arranged by james e. deese (the johns hopkins uni- versity)'. * education planning in government: - ( dec.). arranged by francis x. sutman (temple university). * directions in science education: asia ( dec.). arranged by francis x. sutman. * computers and music ( dec.). arranged by m. v. mathews (bell telephone labora- tories). [part of a symposium on sound and music] * sources of knowledge for child rearing ( dec.). dale b. harris (pennsylvania state university). * the social science disciplines: contributions to basic research in education ( dec.). arranged by howard f. hjelm and lloyd k. johnson (u.s. office of education, washington, d.c.). * aaas vice presidential address (information and communication) ( dec.). quality control: the key issue in information systems, by edward l. brady (national bureau of standards, washington, d.c.). * communicative behavior and the public welfare ( dec.). arranged by robert s. goyer (ohio university). * the effect of educational experience in subsequent education and adult life-models, measurement, and interpretation ( dec.). arranged by ezra glaser (u.s. office of education, washington, d.c.). * education in acoustics ( dec.). mary l. harbold (temple university). [part of a sym- posium on sound and music] * teaching musical acoustics ( dec.). arranged by joseph f. pizzirusso (scott paper company, chester, pa.). [part of a symposium on sound and music] * mathematics and science for the man and woman in the street ( dec.). arranged by r. a. rosenbaum (wesleyan university). * national assessment of educational progress: new findings on achievement in science ( dec.). arranged by lloyd k. johnson (u.s. office of education, washington, d.c.). o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ preliminary program gaylord p. harnwell doi: . /science. . . ( ), - . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the trademark of aaas. is a registeredscienceadvancement of science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for thescience © by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ the effect of monochromatic infrared photo energy on the irritability of myofascial trigger spot of rabbit skeletal muscle research article the effect of monochromatic infrared photo energy on the irritability of myofascial trigger spot of rabbit skeletal muscle ta-shen kuan, , yu-ching lin, , wei-chih lien, , pei-chun hsieh, yu-ting chung, sheng-hsiang lin, and li-wei chou , department of physical medicine and rehabilitation, college of medicine, national cheng kung university, tainan , taiwan department of physical medicine and rehabilitation, national cheng kung university hospital, college of medicine, national cheng kung university, tainan , taiwan institute of clinical medicine, college of medicine, national cheng kung university, tainan , taiwan school of chinese medicine, college of chinese medicine, china medical university, taichung , taiwan department of physical medicine and rehabilitation, china medical university hospital, taichung , taiwan correspondence should be addressed to li-wei chou; chouliwe@gmail.com received april ; revised july ; accepted august academic editor: thomas lundeberg copyright © ta-shen kuan et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. objective. to determine whether the vasodilatation effect of monochromatic infrared photo energy (mire) had the potential for the treatment of myofascial trigger spot (mtrs) in rabbits. design. a randomized-controlled animal study. subjects. twelve adult new zealand rabbits. methods. for each rabbit, a mtrs (equivalent to a myofascial trigger point in humans) in one side of the biceps femoris muscle was randomly selected for mire treatment (experimental side), while another mtrs in the other side (control side) received a sham treatment. the intervention consisted of a daily minutes treatment, three times per week for weeks. the prevalence of endplate noise (epn) loci in the mtrs was assessed before, immediately after, and one week after the completion of the -week treatment. results. mire could suppress the prevalence of epn in the mtrs. the degree of reduction in epn prevalence in the mtrs between the experimental side and the control side was significantly different immediately after mire treatment, but not significantly different one week after mire treatment. conclusion. our study suggests that mire may be a useful therapeutic option for the management of the myofascial trigger point in humans. . introduction monochromatic infrared photo energy (mire) is a type of photobiomodulation. mire has been proposed as a thera- peutic modality for several clinical conditions such as periph- eral neuropathy, wound healing, and pain management [ ]. the device delivering mire, known as the anodyne therapy system (ats), has been approved by the fda for temporarily increasing local blood circulation and reducing pain [ ]. several recent studies of mire focused on the restoration of sensation and wound healing in patients with diabetic peripheral neuropathy [ – ]. however, the effect of pain reduction by mire on a common muscle pain condition, that is, myofascial pain syndrome (mps), has not been fully studied. mps is characterized by the presence of a myofascial trigger point (mtrp), a localized hyperirritable spot in a palpable taut band of skeletal muscle fibers [ – ]. an animal model using rabbits has been developed and found to be very useful for studying the pathophysiology of the mtrp [ , ]. in the adult rabbit skeletal muscle, the taut bands are similar to that in the human muscle and can be identified by finger palpation. when a certain sensitive site in the palpable taut band is squeezed or compressed by a finger, the rabbit would express as if it suffers pain or discomfort (such as screaming, kicking, or withdrawing). the expression is seldom observed when areas outside the sensitive site are compressed. this hypersensitive site is defined as a myofascial trigger spot (mtrs), which is in many ways similar to the mtrp in human muscle [ , ]. hindawi publishing corporation evidence-based complementary and alternative medicine volume , article id , pages http://dx.doi.org/ . / / http://dx.doi.org/ . / / evidence-based complementary and alternative medicine epn mapping sham mire before mire weeks week immediately after mire rabbits collected (n = ) expired (n = ) randomized (sides of biceps femoris) experimental side one side biceps femoris control side the other side biceps femoris rabbits investigated (n = ) one week after mire mire ( min/time, days a week for weeks) figure : diagram of the experimental protocol. epn: endplate noise. mire: monochromatic infrared photo energy. rabbit localized twitch responses, which are similar to human local twitch responses (ltrs) as one characteristic of the mtrp, can be elicited much easier at the mtrs than at other sites in the same muscle [ , ]. another charac- teristic of the mtrp is the electromyographic (emg) activity recorded in the mtrp region, defined as “spontaneous elec- trical activity (sea)” by simons et al. [ ]. sea consisted of two components: the endplate noise (epn) and the endplate spike. epn is recorded much more often in an mtrp region than in a non-mtrp region [ ]. the minute locus from which sea can be recorded has been defined as an active locus of an mtrp [ ]. hong proposed a “multiple loci theory” (many sensitive loci in an mtrp region), and many ltrs can be elicited and many seas can be recorded in an mtrp region [ , ]. it has been shown that the prevalence of epn in an mtrp region is highly correlated with the irritability of that mtrp [ ]. we hypothesize that mire is effective for the management of mps through the vasodilatation effect of mire to improve the local microcirculation. the objective of this study is to test if mire can significantly decrease the prevalence of epn in an mtrs in the rabbit skeletal muscle. . material and methods . . general design. this was a randomized-controlled experiment and was approved by the institutional animal care and use committee of national cheng kung university. the procedures consisted of the application of mire over the mtrs region of the rabbit biceps femoris muscle in one randomly selected side (experimental side) and a sham treatment in the other side (control sides). for sham mire, the diodes were inactivated so that no infrared photo energy was emitted. the prevalence of epn in the mtrs region (epn mapping) in both the experimental and the control sides was measured before, immediately after, and one week after the completion of the whole course ( -week period) of mire treatment (figure ). . . animals. thirteen adult new zealand rabbits ( ∼ kg) were collected but one was expired before the start of the treatment. for the remaining rabbits, each was kept alone in a large cage, with a -hour alternating light- dark cycle, sawdust bedding, and free access to food and water. before anesthesia, one investigator palpated the rabbit’s biceps femoris muscle in both sides with his finger to locate the most tender spot (mtrs) in the taut band. the mtrs was marked, and the rabbit was then anesthetized with an intramuscular injection of ketamine . mg/gbw [ ] over its paraspinal muscle. the skin across the lateral aspect of the posterior thigh was shaved bilaterally and the rabbit was placed on a thermostatically controlled circulating-water evidence-based complementary and alternative medicine taut band sea locus mtrs region figure : the advancement of the recording needle electrode in an mtrs region for searching for sea locus. mtrs: myofascial trigger spot. sea: spontaneous electrical activity. heating pad with the temperature adjusted to ∘c. subse- quent intravenous injections of pentothal at . g/ml were given every – minutes to maintain the anesthetic level so that most of the spinal reflexes were preserved. respiration and rectal temperature were checked every minutes, and heart rate and oxygen saturation were monitored every minutes. instead of fully exploring the biceps femoris muscle with incision of the entire skin, which often resulted in massive bleeding and confounding the vasodilatation effect of mire, only a small longitudinal incision (about ∼ cm) was made over the skin about cm beside the mtrs that allowed the insertion of emg needle. . . assessment of epn prevalence. a -channel nicolet viking iv emg unit was used for the assessment of epn prevalence. the high-cut frequency filter was set at , hz and the low-cut at hz. the gain was generally set at 𝜇v per division for recordings. at the usual sweep speed of ms per divisions, one screen presented ms of record. a mm, disposable, monopolar needle electrode was connected to channel of the preamplifier box of the emg unit and was used to search for the emg activity (sea) of an mtrs. the control needle electrode, which was connected to channel , was inserted into a normal muscle tissue (nontaut band, non-mtrs). a clip used for the surface electrode was attached onto the nearby skin. it was served as the common reference electrode by connecting it to both channels through a “y” connector. the ground electrode was clipped to another site of nearby skin. room temperature was maintained at ± ∘c. the search needle was inserted parallel to the direction of the muscle fibers into the region of an mtrs at an angle of approximately ∘ ∼ ∘ to the surface of the muscle. after the initial insertion to a point just short of the depth of an mtrs, the needle was advanced very slowly. each advance was made through the least possible distance (usually - mm for one advancement) by simultaneously rotating the needle to facilitate smooth entry through the muscle tissue. large advance was avoided because of the minute size of an sea locus and the likelihood of inducing an rabbit-ltr instead of finding a locus of sea. when the needle approached an sea locus, the continuous distant electrical activity (epn) could be heard. the needle was then pressed laterally in four directions (forward and back, right and left), one of which often resulted in appearance of epn. if not, the needle was advanced a minimum distance, which then usually resulted in appearance of epn. a site was an active locus when epn was identified if: ( ) noise-like potentials persisted continuously for more than screens ( ms); ( ) the potential with an amplitude of> 𝜇v (which was more than twice the instrumentation noise level of 𝜇v that was observed in control recordings taken at the beginning and upon completion of each track); ( ) the adjacent control channel did not record potentials greater than instrumentation noise level. there were advancements of needling (each advance- ment about mm) in one needling track in an mtrs region. when the recording electrode approached its end of advancement, it was withdrawn to the subcutaneous level, but not out of the skin, and then reinserted the electrode into another track (maybe mm adjacent to the previous track). there were totally tracks investigated in one mtrs region (figure ). this allowed for the exploration of different loci searching for epn in the region of one mtrs (epn mapping). all the sea loci found in these searching loci in one mtrs region were recorded as the prevalence of epn and were saved for later data analysis. . . application of mire. mire delivers a single (monochro- matic) wavelength of near infrared photo energy at nanometers; the machine delivering mire which we used in this experiment was the anodyne therapy system (ats) (anodyne therapy llc, tampa, fl). the ats consisted of a base power unit and therapy pads, which contained an array of superluminous gallium aluminum arsenide diodes in each pad ( cm × . cm, or . cm ). therefore, mire is evidence-based complementary and alternative medicine a kind of light emitting diode (led). mire delivers pulsed adjustable radiant power of up to milliwatts per diode, a power density per diode array of up to milliwatts/cm , and an energy density of up to . joules/cm /minute [ ]. however, the effectiveness of the photo energy will be influenced by many factors, such as wavelength, radiant power, pulsation, energy density, and skin contact. according to the manufacturer documentations, mire only warms the targeted epidermis slightly; the local heating effect may not be a serious issue. thus the therapy pad with its diode array can be safely placed in direct contact with the skin. the interventional protocol consisted of a session of - minute mire treatment, three times per week for weeks (total treatments). therefore, mire can deliver up to . milliwatts/cm in a -minute therapy session [ , ]. epn mapping was performed by an investigator, who was blinded to the intervention (mire versus sham mire). after epn mapping, the incision in the skin was sutured and the rabbit was kept alive in the same comfortable environment. . . data analyses. for each mtrs, the prevalence of epn was defined as the percentage of total occurrences of epn among searched sites. the mean and standard deviation of the prevalence of epn within each mtrs in either side before mire, immediately after mire, and one week after mire were calculated. the percent change in value after treatment, compared with the pretreatment value using the formula: % changes = (posttreatment value − pretreatment value)/(pretreatment value) × %, was used for statistical analysis. wilcoxon signed rank test was used to compare the values between the control and experimental sides. wilcoxon signed rank test of variance was also used to compare the values before mire intervention, immediately after mire intervention, and one week after mire intervention. a 𝑝 value of less than . was considered statistically significant. . results in the experimental side, the prevalence of epn was obvi- ously decreased immediately after mire application in every rabbit and then was increased one week later except for rabbits # and # (figure ). on the other hand, the changes of the prevalence of epn in the control side immediately after the sham treatment and one week later were not so discernible (figure ). immediately after weeks of mire application, the mean prevalence of epn was significantly decreased compared to that before mire application in the experimental side (𝑝 = . , table ). however, no significant difference was noted in the control side (𝑝 = . , table ). between-group comparison showed a significantly higher reduction in the experimental side than that in the control side (𝑝 = . , table ). the lasting effect of mire, as indicated by the measure- ment taken one week after the completion of -week mire treatment, was also investigated. the mean epn prevalence one week after treatment was significantly lower than that before treatment in the experimental side (𝑝 = . ; table ), but not in the control side (𝑝 = . ). however, between-group comparison showed that the change in epn prevalence in the experimental side (− . ± . %) was not significantly different from that in the control side (− . ± . %; 𝑝 = . , table ). this indicated that the lasting therapeutic effect of mire after one week of its treatment was weak. . discussion our study revealed that the epn prevalence in an mtrs in the rabbit skeletal muscle could be significantly suppressed by the application of mire. in a recent human study of the mtrp in the upper trapezius, kuan et al. [ ] found that there was high correlation (𝑟 = . ) between the prevalence of epn and the pain intensity in the mtrp region, and inversely high correlation (𝑟 = − . ) between the prevalence of epn and the pressure pain threshold. they concluded that the prevalence of epn in an mtrp region has been shown to be highly correlated with the irritability of that mtrp [ ]. therefore, the decrease in epn prevalence in an mtrs could be equated to the suppression of the irritability of an mtrp, which would support our hypothesis that mire is effective for the management of mps. application of mire with nm radiation is supported to increase the localized release of nitric oxide (no) from hemoglobin [ , ]. after being released from nitrosothiols in hemoglobin or from endothelial cells, no will diffuse into smooth muscle cells that line small arteries, veins, and lymphatics [ ]. once being inside the smooth muscle cell, no will activate guanylate cyclase (gc), which enables the cleavage of two phosphate groups from guanosine triphos- phate (gtp). this will result in the formation of cyclic guanosine monophosphate (cgmp), which is important to the phosphorylation of myosin. with myosin being phos- phorylated, smooth muscle cell myosin will relax, and the vessels will dilate [ , ]. no is a potent endogenous vasodilator. through the increased release of no, mire has been reported to enhance microcirculation, which will result in “better blood flow, acute delivery of growth factors and white blood cells, fibroblastic differentiation and prolifera- tion, angiogenesis, reduced edema, and mediation of pain” [ , , ]. according to the current literature, most studies on mire focused on the restoration of sensation in patients with diabetic peripheral neuropathy with mixed results [ – , ]. many of these studies also lack a more robust study design. for example, one study examined the effect of mire in patients with diabetic peripheral neuropathy but did not utilize a control group [ ]. another study of elderly patients evaluated the combined effect of mire and physical therapy; the therapeutic benefits from mire alone could not be addressed [ ]. in addition, the evidence for mire treatment for mps is still lacking. to our knowledge, this experiment is the first placebo-controlled study of the therapeutic effect of mire on mtrs (mtrp). many clinical signs had been proposed for the diagnosis of mps [ , ]. however, controversies still existed regarding evidence-based complementary and alternative medicine . . . . . . . . pre-mire post-mire wk later ep n p re va le nc e (% ) experimental side rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ . . . . . . pre-mire post-mire wk later ep n p re va le nc e (% ) control side rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ rabbit_ figure : the prevalence of epn in an mtrs in the experimental side and the control side before mire, immediately after mire, one week after mire. epn: endplate noise; mire: monochromatic infrared photo energy. table : comparison of epn prevalence between experimental and control sides (between-group comparison) and among conditions in each side (within-group comparison: before, immediately after, and one week after mire application). before mire immediate after mire one week after mire p valuea pre (%) im (%) diffim (%) wk (%) diff wk (%) pre versus im pre versus wk im versus wk experimental side (𝑛 = ) . ± . . ± . . ± . . ± . − . ± . . . . control side (𝑛 = ) . ± . . ± . . ± . . ± . − . ± . . . . 𝑝valueb . . epn: endplate noise; mire: monochromatic infrared photo energy; pre: % epn prevalence before mire; im: % epn prevalence immediately after mire; wk: % epn prevalence one week after mire; diffim: % difference between values before mire and values immediately after mire; diff wk: % difference between values before mire and values one week after mire. values are mean±sd or𝑝value. awilcoxon signed rank test of variance was used to compare the values before mire, values immediately after mire, and values one week after mire. bwilcoxon signed rank test was used to compare the values between the experimental side and the control side. their reliability and validity [ ]. simons recommended that “spot tenderness,” “pain recognition,” and “taut band” were the most reliable signs and the minimal criteria for identifying an mtrp, while “referred pain” and “local twitch response” were most useful as confirmatory signs of the mtrp [ ]. in our animal study, we used “pain recognition” (animal expressed pain), “taut band,” and r-ltr to confirm the location of mtrs. this approach increased the reliability of our findings. travell and simons proposed the “integrated hypothesis of energy crisis,” which has been regarded as today’s most accepted theory for the pathogenesis of an mtrp [ , ]. according to the hypothesis, an initial muscular overload, either from acute trauma, repetitive overuse, or chronic malpositioning, leads to a dysfunctional motor endplate. this results in an excessive release of acetylcholine causing uncontrolled muscle fiber shortening (taut band) and sus- tained contraction of sarcomeres (contraction knot). local circulation will thus be impaired even though the metabolic demand is increased. local hypoxemia and energy crisis are then developed and neurovasoactive substances and neurotransmitters from free nerve endings are also released. in the end, a vicious cycle of energy crisis is formed [ , ]. in a review article, simons [ ] further substantiated this hypothesis into a -step positive-feedback cycle for the pathogenesis of an mtrp (figure ). using a microanalytical technique, shah et al. [ ] measured various biochemicals in the mtrp region in the upper trapezius muscle. these pain evidence-based complementary and alternative medicine taut band (local ischemia + increased metabolism) abnormal ach release increased fiber tension local hypoxia sensitizing substances sarcoplasmic reticulum dysfunction autonomic modulation tissue distress pain 󳰀 (↓ atp) figure : integrated hypothesis for the pathogenesis of an mtrp: a -step positive-feedback cycle (redrawn from simons, [ ]). and inflammation-associated biochemicals were significantly increased in active patients (those with neck pain and mtrp) than in latent patients (those without neck pain but with mtrp) and normal subjects (no neck pain, no mtrp). shah’s findings strongly supported simons’ integrated hypothesis of energy crisis. with its therapeutic effect of vasodilatation, mire shows it could effectively suppress the irritability of the mtrs in the rabbit, which meant mire could improve local circulation and ameliorate the energy crisis in the mtrs region, this further supporting simon’s integrated hypothesis of energy crisis for the mtrp. there have been many therapeutic strategies for the management of mps, including physical modalities (e.g., thermotherapy and electrotherapy, etc.), manual therapy (e.g., spray and stretch and trigger point pressure release, etc.), mtrp injection (e.g., dry needling, local anesthetics, etc.), and medication (e.g., nsaid, muscle relaxants, etc.) [ ]. most of these therapies have been claimed effective, although none has produced consistent, conclusive evidence. a successful mps treatment program should target the underlying pathologies and the perpetuating factors for an mtrp. previously, we reported that botulinum toxin type a, a drug capable of blocking the release of acetylcholine from neuromuscular junction, effectively suppressed the preva- lence of epn in the mtrss of the rabbit [ ]. botulinum toxin type a has now been shown to be an effective therapeutic option for mps. in this study, we reported the short-term effectiveness of mire in decreasing the epn prevalence in the rabbit mtrs. however, the therapeutic effect did not significantly last for more than one week. the long- term efficacy of mire needs to be further investigated, and combining mire treatment with other modalities addressing the etiology of mtrs might be a promising therapeutic strategy. . conclusion the application of mire on the mtrs in the rabbit was shown to significantly reduce the prevalence of epn in the mtrs immediately after treatment. however, the suppressing effect of epn prevalence would not last for one week after the completion of mire treatment. mire could effectively suppress the irritability of the mtrs in the rabbit. our findings in this study suggest that mire may be a useful therapeutic option for the management of the mtrp in humans. conflict of interests the authors declare no conflict of interests. acknowledgments this study was supported by the national science council grant (nsc - -b- - -my ), taiwan. the authors are grateful to shang-chi lee for providing the statistical consulting services from the biostatics consulting center, national cheng kung university hospital. references [ ] t. j. burke, “ questions—and answers—about mire treat- ment,” advances in skin & wound care, vol. , no. , pp. – , . evidence-based complementary and alternative medicine [ ] l. b. harkless, s. delellis, d. h. carnegie, and t. j. burke, “improved foot sensitivity and pain reduction in patients with peripheral neuropathy after treatment with monochromatic infrared photo energy—mire,” journal of diabetes and its complications, vol. , no. , pp. – , . 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[ ] t.-s. kuan, j. t. chen, s. m. chen, c. h. chien, and c. z. hong, “effect of botulinum toxin on endplate noise in myofascial trigger spots of rabbit skeletal muscle,” the american journal of physical medicine and rehabilitation, vol. , no. , pp. – , . kathmandu university 	 	 	 	 		 			 				 						 						काठमाडौं विश्वविद्यालय 					 				 				 					kathmandu university 				 				 				 					 						 								 									students 								 	 								 									examination 								 	 								 									publications 								 	 								 									research 								 	 								 									contact 								 	 							 									 							 	 							 					 				 			 			 				 					 						 			 								 									 										 									 								 							 								 									काठमाडौं विश्वविद्यालय 								 							 							 								kathmandu university 							 							 							 							 								 							 							 								 																			 											 											about ku 																							 													 														 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xi’an , china department of environmental science, aarhus university, roskilde, denmark correspondence should be addressed to liandong zhu; zliand@uva.fi received january ; accepted january ; published may copyright © liandong zhu et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. in response to the energy crisis, global warming, and climate changes, biomass has received a great deal of interest as a promising feedstock for the production of biofuels. biofuels derived from biomass are renewable and sustainable energies with the potential to replace fossil fuels. in addition, the development of biofuels might reduce a country’s reliance on crude oil imports, mitigate greenhouse gas emissions, and increase regional incomes. to determine the stand of the latest available biotechnologies and keep the global academic communities up to date to the current advances in the conversion of biomass to biofuels, this special issue is publishing quality papers with the focus on the application of biotechnology for the production of biomass-based fuels. the paper titled “isoprene production on enzymatic hydrolysate of peanut hull using different pretreatment methods” by s. wang et al. described the work on the use of peanut hull for isoprene production. the authors applied two pretreatment methods, hydrogen peroxide-acetic acid (hpac) and popping, prior to enzymatic hydrolysis. results demonstrated that the isoprene production on enzymatic hydrolysate with hpac pretreatment was about . -fold higher than that of popping pretreatment. the amount and category of inhibitors such as formic acid, acetic acid, and hmf varied among different enzymatic hydrolysates. in addition, results showed that the enzymatic hydrolysate of hpac was detoxified by activated carbon. the paper titled “studies on the ecological adaptability of growing rice with floating bed on the dilute biogas slurry” by q. kang et al. assessed the adaptability and possibility of growing rice on floating beds with diluted biogas slurry. the authors discovered that the growth stage, rice plant height, and rice yield and quality were significantly affected by multiple dilutions. it is found that the rice plants cultivated with multiple dilutions had better ecological adaptability than others. their study showed that it is possible and safe to cultivate rice plants with diluted biogas slurry. the yield, milled rice rate, and crude protein of the rice cultivated with slurry are not as much as those of rice cultivated with regular way in soil. the paper titled “strategies for lipid production im- provement in microalgae as a biodiesel feedstock” by l. d. zhu et al. presents a review on the application of the strategies to activate lipid accumulation, which opens the door for lipid overproduction in microalgae. the review highlights the main approaches for microalgal lipid accumulation induction to expedite the application of microalgal biodiesel as an alternative to fossil diesel for sustainable environment. to promote microalgal biodiesel production during the scale-up process, the achievement of lipid overproduction is essential, and certain appropriate strategies can help realize the goal. but, in practice, the lipid-inducing strategies can also be com- bined in an effort to achieve lipid production optimization. the paper titled “simultaneous saccharification and fer- mentation of sugar beet pulp for efficient bioethanol pro- duction” by j. berłowska et al. explored an approach to inves- tigate the effects of pretreatment, the dosage of cellulase and hemicellulase enzyme, and aeration on the release of fermentable sugars and ethanol yield during the simultaneous saccharification and fermentation (ssf) of sugar beet pulp- based worts. the results showed that a h interval for enzymatic activation between the application of enzyme preparations and inoculation with ethanol red could further hindawi biomed research international volume , article id , pages https://doi.org/ . / / https://doi.org/ . / / biomed research international improve the fermentation performances, with the highest ethanol concentration reaching . g/l and . % fermen- tation, compared to the theoretical yield. the paper titled “application of the initial rate method in anaerobic digestion of kitchen waste” by l. feng et al. developed a method of methane production through the determination of the hydrolysis constants and reaction orders at both low total solid (ts) concentrations and high ts concentrations. the results showed that the first-order hydrolysis model better reflected the kinetic process of gas production. during the experiment, all the influential factors of anaerobic fermentation retained their optimal values. for a long reaction time, the authors believed that the hydrolysis involved in anaerobic fermentation of kitchen waste could be regarded as a first-order reaction in terms of reaction kinetics. the paper titled “outdoor growth characterization of an unknown microalga screened from contaminated chlorella culture” by s. huo et al. used s rdna molecular technol- ogy to isolate and identify one wild strain scenedesmus sp. f. s. from the culture of chlorella zofingiensis. the authors discovered that scenedesmus sp. f. s. showed good alkali resistance and robust adaption to the stress of the outdoor environment. furthermore, under normal conditions, the oil content of scenedesmus sp. f. s. could reach more than . %, and c –c content could reach up to . %, showing that it had great potential as a large-scale cultivation strain for biodiesel production. the paper authored by c. quan and n. gao provides a review on the copyrolysis of coal and biomass and then com- pares their results with those obtained using coal and biomass pyrolysis in detail. they also discuss the effects of reaction parameters such as feedstock types, blending ratio, heating rate, temperature, and reactor types on the occurrence of synergy and point out the main properties of the copyrolytic products. the paper written by k. t. dasa et al. examined the inhibitory effects of lcfas (palmitic, stearic, and oleic acid) on biogas production as well as the protective effect of a membrane bioreactor (mbr) against lcfas. their findings showed that palmitic and oleic acid with concentrations of . and . g/l resulted in > % inhibition on the biogas production, while stearic acid had an even stronger inhibitory effect. the encased cells in the mbr system were found to be able to perform better in the presence of lcfas. the paper authored by i. masin and m. petru dealt with the complex approach to design specification that could bring new innovative concepts to the design of mechanical machines for oil extraction. their presented case study as the main part of the paper focused on the new concept of the screw of machine mechanically extracting oil from jatropha curcas l. seeds. the paper written by wang et al. conducted the ftir analysis which showed that the chemical structure of lignin was broken down in the lhw process. in addition, they also explored the impact of untreated and treated lignin on the enzymatic hydrolysis of cellulose. they also found that the lhw-treated lignin had little impact on the cellulase adsorp- tion and enzyme activities and somehow could improve the enzymatic hydrolysis of cellulose. acknowledgments we would like to thank all the authors for their excellent contributions to this special issue. liandong zhu ningbo gao rong-gang cong legal cultivation on low-carbon use of china's high-carbon resources available online at www.sciencedirect.com energy procedia ( ) – – © published by elsevier ltd. doi: . /j.egypro. . . iaceed legal cultivation on low-carbon use of china’s high-carbon resources guo lia,b , ding sanqinga, cui qiangc, zhu yunlanb aschool of managem ent .china university of mining and technology , xuzhou, , jiangsu province, china bxuzhou institute of technology, electronic engineering departm ent, xuzhou , jiangsu province, china cxuzhou air force academ y, xuzhou , jiangsu province, china abstract fully reviewed the existing laws and regulations for high- carbon resources and low carbon ization use of the p rovisions, inductived the p resent deficiency in p resent legal sy stem for high-carbon resources and low carbonization use p ointed out that we should p lay the role of breeding of env ironmental r esources to achieve sustainable develop ment objectives. keywords: high-carbon resources; low-carbon use; legal cultivation . introduction heavy industry plays a very important role in our industrialization develop ment stage, which is with high energy consumption, lo w effic iency and heavy pollution. and coal with high carbon hold a leading post in fossil energy. coal will occupy a pro minent place in the very long period because of fossil energy characteristics and renewable energy status . coa l p lays a main ro le in energy structure (about % ), which is the main energy and an important raw material fo r chemica l industry. coal as carbon highest carbon energy, the high carbon energy development d irection is to low-ca rbon use of china’s high-carbon resources . the basic require ments of low-carbon us ing of china’s high-carbon resources is the high efficiency, lo w e mission and less pollution, rea lizing ways fro m the source, the process to include the whole life cyc le of the terminal. increase the proportion of coal washing, reducing coal output and direct combustion, fro m the source control of pollutants, and developing coal conversion technology promptly, * corresponding aut hor. tel.: ; e-m ail address: cqglglcq @sina.com. open access under cc by-nc-nd license. © published by elsevier ltd. selection and peer-review under responsibility of riuds open access under cc by-nc-nd license. http://creativecommons.org/licenses/by-nc-nd/ . / http://creativecommons.org/licenses/by-nc-nd/ . / guo li et al. / energy procedia ( ) – such as the all-round, advanced combustion, low carbon products synthesis technology . lowe r coal consumption strength, reduce the pollution e mission process . increase coal and coal consumption and product management and control of pollutants and realizat ion of coal and coal c leaner product. on top of this , to achieve h igh carbon energy use lo w ca rbonizat ion of this goal, we need to ta ke co mp rehensive safeguard way, including technical, economic and legal aspects . with the characteristics of mandatory, stability, authority and normative in law, the function of law in many ways of guarantee superiority has important function. . the legal connotation on low-carbon using of china’s high-carbon resources at present, the low-carbon using of china’s h igh-carbon resources focuses on technical leve l ca rbide, it can be detected that, there are three meanings on lo w-carbon using of china’s h igh-carbon resources from the legal angle: . . high-carbon resources supply security which means in a fa ir and reasonable steady range, to achieve h igh carbon and energy resources using low ca rbide in the technology, and there is rich enough high carbon energy resources supply to meet in the social development of the country or region, the economic development and social stability . . . high-carbon resources economic efficiency that means to make economic and utilizat ion of energy coordinate develop ment in the base of low- carbon using of china’s high-carbon resources. in the first place, it is the saving of high carbon energy resources and using efficiency, and to realize the sustainable development. . . high-carbon resources environmental protection that means to reduce the high ca rbon energy on the environ ment and the e ffects of climate change, energy, and resources coordinating strategic and environmental protection . on the ecologica l environ ment protection in the develop ment and utilizat ion of energy resources, high carbon in h igh energy resource utilization of low carbonization to protect the ecologica l environment. high-carbon resources supply security, high-carbon resources economic effic iency and high-carbon resources environmental protection should be coordination development. the three aspects are integrated, equally important and inseparable. it is shown in chart . th e l e gal con n otati on high-carbon resources supply securit y high-carbon resources economic efficiency high-carbon resources environment al p rot ect ion guo li et al. / energy procedia ( ) – fig. . legal connotation of low-carbon use of china’s high-carbon resources there are d ifferent types of diversificat ion, each with varying characteristics and levels of risk, and it is a set of s ystem of production, transportation, distribution and utilizat ion in diffe rent degree of high carbon and energy resources . and in the environmental permit within the scope of the state or the basic guarantee of different areas of high carbon energy resources supply security. . the legislation of low-car bon use of china’s high-carbon resources there were so many relig ious doctrine, the family pla in speaking and legislation about environment protection lifestyle in ch ina. after thousands of years of adjustment, enrich and develop, they played significant influences in the cultural of country environment. the modern ru le of ch ina, lega l culture of low-ca rbon use got a lot of environmental resources legislation confirmat ion and reflects . for nearly a decade, total issued dozen laws , whether the number of la ws and frequency are showing the urgency of cultivating low carbonization use or importance. and legal increasingly meticulous and overall t able .legislation of low-carbon use of china’s high-carbon resources legal name t ime development of circular economy t he p revention and control of water p ollution count ry planning law energy conservation law renewable energy law t he law of p revention of environmental pollution caused by waste t he law of p revention and control of desertification administ rative permission law t he law of p revention and control of radioactive pollut ion t he law of evaluation of environmental effects wat er law t he law of p romotion of p romotion of cleaner p rodut ion in a co mprehensive legislat ion and policy level energy conservation law in a c learly defined in article of the energy of the species : refe rred to energy by means of coal, oil, natural gas, biomass energy and power, and heating and other directly or through processing, transform and obtain useful can of all kinds of resources. the third middle finger and clear low carbonization connotation : referred to save energy (hereinafter refe rred to as the energy s aving) refers to strengthen energy -using manage ment, adopt feasible in technique and reasonable in econo my and environ ment and socially guo li et al. / energy procedia ( ) – acceptable measures, fro m energy production to the consumption of each link, lowe ring consumption and reduce the loss and emission and stop wasting, effective and reasonable utilization of energy. . legal cultivation on low-carbon use of china’s high-carbon resources . . further implementing the strategy of sustainable development at the un confe rence on environ ment and de velop ment (unced), governments made a commit ment to adopting national strategies for sustainable development. the strategies for sustainable development called for at rio are foreseen as highly participatory instruments intended "to ensure socially respons ible economic development while protecting the resource base and the environment for the benefit of future generations". the oecd's "shaping the st century" ( ) ca lls for the formu lation and imple mentation of such strategies in every country by - one of the seven international develop ment goa ls (idgs) - and for development co-operation agencies to support such processes in developing countries. the specia l session of the un general assembly set a target date of for introducing strategies . . . to improve the government energy management system high carbon energy is related to the national economy industry , low carbonization use must give full play to the government's important role . the need to build a fro m the central to local unified, in ene rgy strategy management as the core of energy management system, issued some coordinated with high carbon energy low ca rbonization method to utilize the measures and imple mentation of super depart ment, authority, manage ment and coordination. meanwhile, the government should emphasize the formu lation of high carbon energy low carbonization utilization of co mp rehensive macro policies, imp le menting strategic management, ensure market fair and orderly competit ion, make scientific ma rket forecast and improve the information service and plays important role. . . perfect high carbon energy of legal system international e xperience shows that sound legal la ws and regulations is the cornerstone of imple menting the strategy of sustainable development , so we should improve the current energy system: first of all, to perfect coa l law of the people's republic of china .there are some problems in this law, behind the situation and practical work of the need, we need to revise and improve. secondly, even high carbon energy formu lated perfect legal system; including high carbon energy admin istrative regulations has irreplaceable role . finally, but also strengthen the perfect law enforcement system; strengthen the supervision and inspection of high carbon energy low carbonizat ion using lawful implementation management. . . to establish a high carbon energy strategy reserve system establish energy strategy and business reserve system safeguard the country's energy resources required security measures . its denotation shall include the minera l reserves , resource capacity reserves, resource products spot reserves, product futures reserves, equity resources reserve (as in fore ign important resource mining areas of mining right, the mining investment of resources distribution of inco me, e tc.), resource technical reserves six ways, especially attention should be paid to the resource product futures and resources exploitation rights two aspects of reserves. guo li et al. / energy procedia ( ) – high carbon energy strategic reserves are not only high carbon energy resources produ ct storage or reserve problem, mo re important is to capacity building and system construction. from our national characteristics and shall fro m country, province, la rge corporations and important bases and strategic pool, the four levels of society, establish mult iplication, e lastic high carbon energy strategy reserve system. through legislation form, appropriate proportion, mandatory provisions on high carbon strategic energy reserves; different levels of strategic reserves, take diffe rent forms , bear d iffe rent reserve task. through legislation form, appropriate proportion, mandatory provisions on high carbon strategic energy reserves; different levels of strategic reserves, take different forms, bear different reserve task. . . to establish high carbon energy warning and coping mechanism the main purpose of this mechanism is early wa rning and risk t ime ly countermeasure . in case of an eme rgency, high carbon energy warning and coping mechanisms to prevent and cast off the crisis will become an important link in the system. which is div ided into three stages: one is high carbon energy crisis happened before the eme rgency preparatory; two is h igh carbon energy crisis reward ing of stage, three is high carbon energy crisis occurred after the management deal with stage . acknowledgements we wish to thanks professor ding sanqing of ch ina unive rsity of mining and technology for many helpful suggestions . we are thankful and acknowledge the support of xuzhou institute of technology, electronic engineering department. references [ ] wang jirong, brendang et al. improve policies implement at ion mechanisms to ensure t he realizat ion of emission reduct ion t argets .j environmental p rotection ; (cciced special): - . [ ] zhang deyi.some considerations about china’s sit uation. j p etroleum&petrochemical today ; ( ): - . [ ] shen baohong,zhao luzheng.analysis on swit ching from high-carbon to low-carbon energy ut ilizat ion of coal. j energy of china ; : - . [ ]xu hongxing.energy ut ilization in china and countermeasures. j sino-global energy ; : - . [ ] xiao qianang.the law of energy. law p ress china , beijing: e-p ublishing inc; , p. - . [ ] huangjin. china's energy safety research. wuhan university press. ,p. - . [ ] chen qingt ai. chinese national energy st rategy and policy.http://www.drcnet.com.cn/ wsn for appliance control wsn for appliance control prof. dr. ram joshi , aksha gavate , sweety gholap , sayali kumar , sonali patil savitribai phule pune university professor, student, department information technology, jspm's rajarshi shahu college of engineering, tathwade, pune abstract: solar energy is a very useful renewable source of energy, which may be the answer to the future for power, or energy needs, as global warming seems to pick up rapidly. we can reduce global warming problem by using solar energy thus diminishing or trimming down various gas emissions, which can damage earth, in turn, the millions of people in it. by installing solar lights in college premises, it will help to reduce the energy crisis. arduino act as a main controller which connects various sensors and other modules. by using automatic turning on/off lights can also reduce the energy and will save the power. using android application user can manually control lights. this application conjointly focuses on motion detection and darkness detection by providing security to application against unauthorized user. so, by installing solar lights in college premises, it will help to boost the economy of india. keyword: solar panel, solar battery, arduino, pir and ir sensor, ldr sensor, bluetooth module. introduction the increase of energy crisis everywhere over the planet has created problem which can be reduced by using solar energy. a method is to look at the new energy and profit of the renewable energy. utilization of the new energy-saving technologies to scale back energy consumption, and improve utilization potency of energy. alternative energy is the most direct, common, and clean energy. the star resources are often appeared inexhaustible. alternative energy could be a helpful renewable supply of energy, which can be the solution to the long run for power, or energy wants. so, we will all contribute to the surroundings by victimisation alternative energy so erasing or trimming down numerous gas emissions, which may endanger earth. automation could be a technique or a way or a system in operation using electronic devices by reducing human involvement to a minimum. the elemental of building an automation system for a workplace or house is increasing day-by-day with sizable amount of advantages. men of affairs, researchers and students square are working to make economical and affordability automatic systems to watch and manage totally different machines like lights, fans, ac supported needs. automation is another necessary application of wireless technologies like bluetooth, wi-fi. it's the observance of the energy consumption and therefore the dominant surroundings in buildings, schools, offices and museums by different kinds of sensors that manage lights, temperature, motions, darkness. to create it a lot of operative and economical, price is reduced by low price communication technology like bluetooth. bluetooth could be a technology that permits the users fast connections between many devices in real time. the means of transmission used, assures protection against interferences and safety within the causing of data is up to one hundred meters. building upon this theme; we tend to propose an electrical device which may be charged by solar energy, supported bluetooth technology on the market in automaton smartphones. our paper presents bluetooth based mostly centrally controlled home automation system victimisation smartphones and arduino uno board. such a system can modify users to own management over lights like corridors with bluetooth. all that the user wants is a smartphone, that is in virtually everybody’s hand today, and an arduino microcontroller circuit. the feedback circuit consists of an arduino uno microcontroller, that processes the user commands and controls the shift of devices. when darkness and movement is detected, light will automatically glow. the association between the microcontroller and therefore the smartphone is established via bluetooth, a widespread wireless technology used for sharing knowledge. this application conjointly focuses on motion detection and darkness detection by providing security to application against unauthorized user. literature survey implementation of passive infrared sensor in street lighting automation system by n. l. ramli, n. mohd yamin, suliana ab ghani, n. md. saad and s. a. md sharif [december ] in this paper the authors have projected a sensible street lighting system that provides a secure evening time setting for all road users and pedestrian. the most objectives were to create associate in nursing automation system of street lighting employing a low-priced microcontroller that is arduino and to realize energy-saving. this technique required to be controlled in line with the particular mode. these modes square measure controlled by devices that square measure lightweight dependent resistance (ldr) and passive infrared (pir) sensor. this technique will mechanically activate and off the lights in line with traffic flow. this technique operates throughout the night and therefore the focus is barely for the unidirectional road at a junction. street lightweight are on once solely there's road user otherwise, it'll close up. this style will save an excellent quantity of electricity or energy consumption compared to standard street lights that keep alight throughout nights. international journal of engineering research & technology (ijert) issn: - http://www.ijert.org ijertv is (this work is licensed under a creative commons attribution . international license.) published by : www.ijert.org vol. issue , february- www.ijert.org www.ijert.org www.ijert.org bluetooth based home automation system using cell phone by rajeev piyare, m. tazil [june ] in this paper the authors have advised the planning and implementation of an occasional value however nevertheless versatile and secure cell phone-based home automation system. the planning was supported a standalone arduino bt board and therefore the home appliances square measure connected to the input/ output ports of this board via relays. the communication between the telephone and therefore the arduino bt board was wireless. this technique was designed to be low value and scalable permitting type of devices to be controlled with minimum changes to its core. countersign protection was wont to solely enable authorised users from accessing the appliances reception. during this paper we tend to gift an occasional value secure telephone based mostly, versatile home automation system employing a secured communication between human and therefore the system, that's using a bluetooth module. pir and ir sensor based smart home automation system using iot for energy saving applications by p. eben sophia, prithvirajan r., thirunavukarasu s., muthuraj k., s. sarmila [june ] in this paper the authors have put forth an provide automatic electronic appliance on/off using pir sensor. this design was proposed using pir sensor for automation of lights and fans using arduino with internet of things for smart homes. the presence of pir sensors ensured that the lights turn on and off according to motion it senses. this design represents the role of arduino uno board in controlling the operation of pir sensor and electrical components in the framework. the arduino gets a flag from pir, which turns on the lights, fans or electrical appliances. every single seconds arduino checks the signs from the pir sensor and whenever it gets yield as ' ' (high) then it won't cut-off the primary voltage and whenever it gets yield as ' '(low) at that point the voltage is cut-off and the appliance terminates its functioning. solar powered led-based lighting facilities by patrizio primiceri and paolo visconti [january ] in this paper, the authors have reported on new technological trends and devices employed in construction of advanced solar powered led based lighting systems, which can be used for both outdoor and indoor applications. this paradigm proved to be choicest in controlling and driving the led-based lighting facilities, that can be provided of integrated sensors, thus realizing new lighting functionalities, improved management of the energy. sun light can be converted into dc electricity when it falls on the top surface of the solar cells inside the pv module by means of photovoltaic conversion process. this system integrate ssl technology, low-cost sensors, smartphones and iot- based devices and must fulfil the expectcation to facilitate new lighting functionalities and a great exchange of data among lighting systems, installed everywhere both inside or outside of buildings. related work the solar panel is the core part of the solar light system which converts the sun's radiant energy to electrical energy, and then transmits through the controller to be stored in the battery. the battery which is connected to the arduino and transmit the power while the light glows. it is basically comprising of four mechanism. ) connection of arduino with solar system arduino board module, facilitated with a solar panel and a battery, can power your arduino project in two ways: either by connecting your arduino board to the module and the module to its solar panel or by connecting the battery to the solar module then the solar module to your arduino board via a pair of wires. ) connection of arduino with bluetooth this circuit is simple and small. the arduino and bluetooth module has only four connections. arduino pins --> bluetooth pins px (pin ) ----> tx tx (pin ) ----> rx v ----> vcc gnd ----> gnd international journal of engineering research & technology (ijert) issn: - http://www.ijert.org ijertv is (this work is licensed under a creative commons attribution . international license.) published by : www.ijert.org vol. issue , february- www.ijert.org www.ijert.org www.ijert.org ) connection of arduino with pir and ir sensors the pir sensor and ir sensor detects movement in front of it and signals arduino. arduino will activate an alarm in the form of a buzzer, whenever any movement is detected. connect the negative wire of the ir sensor and pir sensor together and then connect to gnd on the arduino. connect the middle of the ir and pir sensors which is the vcc to v on the arduino. pin of the arduino is connected to the signal pin of the ir sensor. )connection of arduino with ldr sensor the setup is very simple: connect + v of the arduino to one pin of the ldr connect the other pin of the ldr to a and one pin of the kΩ resistor. connect the other pin of the kΩ resistor to gnd of the arduino. conclusion however, the efficiency of the solar cells is increasing, while the price is decreasing. however, the efficiency of the solar cells is increasing, while the price is decreasing. at same time, the efficiency of the led light is in a rapid increase, but the prices are lower. automatic light control mechanism saves the power and energy. and it is step towards the automation world. so following development of the outdoor lighting technic, the solar led light system has shown us it will have promising application and infinite vitality. references [ ] daniel f. butay, michael t. miller. "maximum peak power tracker: a solar application" april th, . [ ] "lab – electrical characteristics of photovoltaic cells " school of electrical and information engineering, university of sydney. semester , . [ ] pan shiquan "application research in the solar street lamp management based on the led light-emitting diodes" bulletin of science and technology, vol. no. apr. . [ ] p. tenti. "dispense del corso di elettronica industriale". università degli studi di padova. [ ] t. esram. "comparison of photovoltaic array maximum power point tracking techniques" energy conversion, ieee transactions on(volume: issue: ). . international journal of engineering research & technology (ijert) issn: - http://www.ijert.org ijertv is (this work is licensed under a creative commons attribution . international license.) published by : www.ijert.org vol. issue , february- www.ijert.org www.ijert.org www.ijert.org mechanical alloying and spark plasma sintering of higher manganese silicides for thermoelectric applications yatir sadia, , liron dinnerman, and yaniv gelbstein .—department of materials engineering, ben-gurion university of the negev, beer sheva, israel. .—e-mail: yatttir@yahoo.com the present challenges in the energy crisis require finding new ways to reduce consumption of fossil fuels. thermoelectrics can help reduce fuel consumption by producing electricity from waste heat. the higher manganese silicides (hms) have shown promise in this field as inexpensive, nontoxic, and highly stable p-type thermoelectric materials. one of the production techniques for hms is mechanical alloying by ball milling. in this research the effect of the ball-milling duration and speed on the phases produced was studied. mn and si powders were milled at speeds of rpm to rpm for h to h. x-ray diffraction (xrd) results of the samples prepared using mechanical alloying show deterioration into the mnsi phase. the sample that underwent h of milling at rpm showed the greatest amount of hms phase and was subsequently spark plasma sintered. the sample showed insufficient ther- moelectric properties (zt � . at �c), compared with either solid-state reaction samples showing zt � . or cast samples showing zt � . at �c. the reduced zt values of the mechanically alloyed and spark-plasma- sintered samples were attributed to the high relative amount of mnsi phase. the correlation between the relative amount of mnsi and the transport properties is described in detail. key words: higher manganese silicides, thermoelectric, mechanical alloying, spark plasma sintering introduction in the past few years, rising fossil fuel prices and greenhouse effects have shifted the world view on renewable energy sources. while various methods of energy conversion exist, one of the most exciting is thermoelectric technology, which satisfies the requirements for long-term stability and low main- tenance. this is made possible due to the fact that thermoelectric systems have no moving parts. one of the most important measures of the efficiency of a thermoelectric material is the dimensionless figure of merit (zt), defined as the square of the seebeck coefficient times the temperature over the electrical resistivity times the thermal conductivity. while various materials possess desired properties for thermoelectric performance, chalcogenides such as bismuth telluride, germanium telluride, and lead telluride mainly dominated the field in the past. however, while the thermoelectric properties of chalcogenides result in high figure-of-merit values, they have not been successfully introduced into mass production, being limited to rather minor, specialized applications. this has been due to some of their other characteristics, including inferior mechanical properties, toxic lead content, high price of base materials, and high vapor pressure at their peak efficiency temperatures. in the past few years, several materials have shown thermoelectric properties comparable to those of the chalcogenides. such families of materials include skutterudites, half-heuslers, and metal sili- cides. while all of these material classes have specific merits, metal silicides have attracted much attention due to their low materials cost, high chemical and (received june , ; accepted january , ; published online february , ) journal of electronic materials, vol. , no. , doi: . /s - - - � account suspended account suspended this account has been suspended. contact your hosting provider for more information. pressured shale and related sediment deformation--mechanism for development of regional contemporaneous faults: abstract; diversity-equitability analysis as paleoecologic tool: abstract; paleomagnetism of late pleistocene-holocene sediments, gulf of... association round table shore winds is moved into clay dune complexes and eventually carried downwind to develop loess sheets. this extensive up- wind deflation of the system is accompanied by windward accreting clay-sand ridges with nuclei composed of either beach-ridge remnants of a pleistocene barrier-strandplain sys- tem or remnants of inter-blowout areas developed during early phases of the deflation of the coastward margin of the system. principal source of sand and loess is, therefore, local, repre- senting reworking of underlying, older sands. a sand source resulting from longshore convergence and inland transport from padre island accounts for only the minor, local infllling of laguna madre in the land-cut area, and is not the principal source of eouan sand throughout the system. facies fabric within pleistocene depositional systems provides principal con- trol of environments, sedimentary processes, and resulting fa- cies within the subsequent eolian system. bruce, c. h., mobil oil corp., corpus christi, tex. pressured shale and related sediment deformation—mecha- nism for development of regional contemporaneous faults regional contemporaneous faults of the texas coastal area are formed on the seaward flanks of deeply buried unear shale masses characterized by low bulk density and high fluid pres- sure. from seismic data these masses have been observed to range in size up to mi wide and , ft vertically. these features, aligned subparallel with the coast are en echelon or branching in pattern, and represent residual masses of under- compacted sediment between sand-shale depoaxes in which greater compaction has occurred. most regional contemporane- ous fault systems in the texas coastal area were formed during times of shoreline regression when the duration of fault devel- opment extended over short periods of geologic time, and where comparatively simple down-to-the-basin fault patterns were developed. in cross-sectional view, faults in these systems flatten and converge at depth to planes related to fluid pressure, and form the seaward flanks of underlying shale masses. data indicate that faults formed during time of shoreline regression were developed primarily through differential compaction of adjacent sedimentary masses. these faults die out at depth near the depoaxis of the sand-shale section. in areas where subsidence exceeded the rate of deposition, gravitational faults developed where basinward sea-floor incli- nation was estabushed in the immediate area of deposition. some of these faults became bedding plane type when the incunation of basinward-dipping beds equaled the critical slope angle for gravitational slide. fault patterns developed in this manner are comparatively complex and consist of numerous antithetic faults and related rotational blocks. nondepositional (structural) faults are common on the land- ward flanks of deeply buried shale masses. many of these faults dip seaward and intersect the underlying low-density shale at relatively steep angles. conclusions derived from these observations support the concept of regional contemporaneous fault development through sedimentary processes where thick masses of shale are present and where deep-seated tectonic effects are minimal. butler, e. a., and h. w. simpson, atlantic richfield co., dallas, tex. dlversnt-equitability analysis as p a l e o e c o l o o i c t o o l diversity-equitability analysis of microfaunal data as used by beerbower and jordan shows promise of being a rapid and useful technique for mapping paleoenvironmental gradients. it may even provide a more satisfactory definition of environmen- tal boundaries than biofacies analysis based on taxonomic com- position. faunal diversity is calculated as shannon's information the- ory average uncertainty measure. using this diversity measure, a few equally common taxa can yield as high a diversity index as many unequally common taxa. lloyd and ghelardi's equita- bility index may be used to separate these two diversity compo- nents and refine seemingly homogeneous data. recent microfaunal data from barnstable harbor, massa- chusetts, and the northern gulf of mexico have been subjected to diversity-equitabihty analysis. from barnstiible harbor, con- tours based on the equitability index can be related rather clearly to tidal action within the harbor. a diversity-equitability plot of published holocene gulf of mexico data reveals that some environments may be characterized by a unique d / e range. although these results must be considered preliminary, an analysis of parts of the lower miocene sequence in block field, high island area, oflshore texas, shows that the techni- que merits further consideration and is potentially a very useful tool for both identifying and mapping ancient environments. clark, h. c , dept. geology, rice univ., houston, tex. paleomagnetism of late pleistocene-holocene sediments, gulf of m e x i c o detailed paleomagnetic studies have been made on sedi- ment cores selected along north-south lines in the eastern and western gulf of mexico. the piston cores were sampled at - cm intervals immediately upon extrusion and measurements of natural remanent magnetization (nrm) were made using a hz spinner magnetometer. excursions of the geomagnetic field are recorded at levels in many cores. extrapolation of the zy boundary in the western gulf indicates that the younger feature is between . and . x ' years bp, and is consistent with the age determination of the laschamp event. dates are not available for the eastern gulf cores, but the depth of the paleo- magnetic feature correlates with the expected sedimentation rates. the older feature is less distinct and further extrapolation of the zy boundary places it between . and . x \(fi years bp. this age is within the range of a geomagnetic feature that is not the laschamp. these re ".ults show that with extreme care, paleomagnetic measureme its may be used as a stratigraphic tool in the gulf of mexico. several points should bi considered. first, because of the high sedimentation rates, the yotmg features described herein are the only ones expected in piston cores from this region. second, direction scatter is quite pronounced in the upper / m and lower few centimeters of several cores. corre- lations at these levels are difficult. finally, as measurement of the geomagnetic features described lasted for only a short time and did not traverse a full °, dense sampling is recom- mended to assure their definition. crandall, k. h., consulting geologist, piedmont, cauf economic and other factors affecting petroleum exploration there is today almost universal agreement that we are facing a potential energy crisis, both imminently in the u.s. and possibly worldwide after the turn of the century. all studies of energy supply and demand indicate such tremendous growth in demand tiiat conventional sources will be hard pressed to sup- ply it. the short-range aimual growth rate in domestic and free- world demand for petroleum is estimated at % and / % respectively, resulting in million and million bbl/day total demand in . by u.s. demand will be nearly million bbl and free foreign need nearly miuion bbl/day. the areas which will supply this demand, especially for fhe u.s., ark quite imcertain because of the bewildering variety of poutical, legal, and environmental factors—as contrasted with purely economic ones—which will be of critical influence. therefore, it is difficult to forecast the areas and the amounts and costs of exploration and development, as well as prices and earnings. one thing is certain, however, there will be a growing short- age of domestic crude and an increasing dependence on foreign suppues. both the cost and dependabiuty of the latter are questionable in view of political considerations and the policies and actions of opec. fpv n _toc_toc functional plant biology evans review: energy-crises in well-aerated and anoxic tissue: does tolerance require the same specific proteins and energy-efficient transport? hank greenway and william armstrong – review: trafficking to the seed protein storage vacuole joanne r. ashnest and anthony r. gendall – exogenous spermidine enhances the photosynthetic and antioxidant capacity of rice under heat stress during early grain-filling period she tang, haixiang zhang, ling li, xia liu, lin chen, wenzhu chen and yanfeng ding – calcium oxalate degradation is involved in aerenchyma formation in typha angustifolia leaves xiaomin du, xiaolong ren, lingli wang, ke yang, guiliang xin, guolun jia, xilu ni and wenzhe liu – effects of nutrient supply on carbon and water economies of c grasses laura rose, robert buitenwerf, michael cramer, edmund c. february and steven i. higgins – we review metabolic adaptations of plant tissues to severe reductions in energy-production (‘energy-crises’) that occur in various situations, including o -deprivation during flood-events. we conclude that most major differences between tissues intolerant and tolerant to an energy-crisis are associated with only a few gene-proteins. these concern efficient energy production and energy-efficient-transporters, necessary to retain membrane integrity, essential to life. increasing global demand for high quality, plant-based proteins has driven a strong interest in the sorting and processing of seed storage proteins. this review summarises recent primary research findings regarding vacuolar trafficking and seed protein biology, in the context of established and novel paradigms. we also highlight several key gaps in the scientific understanding of these processes. frequency and intensity of high temperature negatively affects rice production in china and challenges food security, thus appropriate mitigation measures urgently need to be proposed. from the photosynthetic and antioxidant capacity aspects, exogenous spermidine effectively alleviates the adverse consequences of high temperature. findings from this study may provide strategies in mitigating the challenges of global warming- induced yield loss and other possible relevant issues. the developing aerenchyma of typha angustifolia is accompanied by calcium oxalate crystals (caox). the degradation of caox crystals causes high levels of h o , which is considered a key signalling molecule that triggers programmed cell death (pcd). it suggested that caox degradation is involved in the regulation of the pcd process of aerenchyma in t. angustifolia leaves. whether plants can induce mass flow of nutrient-rich soil water via increased transpiration might influence their competitive strength. we tested the response of c grasses to low nutrient availability at the roots but found no physiological indication of active mass flow induction. this can mean a competitive disadvantage of water-efficient c plants to c plants under high atmospheric co . cover illustration: calcium oxalate crystals in typha angustifolia leaves (see du et al. pp. – ). image by xiaomin du. contents volume issue . /fpv n toc does foliage metal accumulation influence plant–insect interactions? a field study of two sympatric tree metallophytes denise r. fernando, chaya s. smith, martin j. steinbauer, kevin farnier, simon j. watson and peter t. green – quantitative trait locus analysis of adventitious and lateral root morphology of barley grown at low and high p jingyi guo, guangdeng chen, xizhou zhang, tingxuan li, haiying yu and chunji liu – leaf acclimation strategies to contrasting light conditions in saplings of different shade tolerance in a tropical cloud forest ana quevedo-rojas, carlos garcía-núñez, mauricio jerez-rico, ramón jaimez and teresa schwarzkopf – the defence capacity of metal-rich foliage in two rainforest tree species was examined via a field study. plant–insect interactions associated with tree metallophytes remain poorly understood. although there was no direct evidence here of metal defence, the study found indirect effects, and evidence of adaptation by a galling insect that exploits foliar metal. this field study revealed complex ecological relationships undetectable by controlled experiments. this research demonstrated the different growth dynamics in adventitious and lateral roots of barley in response to low-p stress and detected quantitative trait loci (qtls) for them. lateral roots play a role in p uptake in barley. the new qtl region cl– h had great potential for future genetic improvement of barley lateral root growth and may offer valuable clues for fine mapping in barley. to survive, saplings of tree species in the understorey of tropical cloud forests must acclimate to sudden and gradual changes in the light environment. in an acclimation experiment, we found that species showed different strategies in leaf photosynthetic responses combining gas exchange, photoinhibition and other properties. knowing these strategies could explain saplings’ distribution along the light gradient and produce insights into species’ requirements for forest management or restoration plans. original article summary objective: the authors show the clinical evaluation and follow-up results in pa- tients diagnosed with a failed back surgery pain syndrome. methods: descriptive and prospective study conducted over a one-year period. in this study, patients with a failed back surgery pain syndrome were assessed in our facility. the age ranged from to years (mean, .  ±  . years). the pain was assessed through a visual analog scale (vas). results: postoperative pain was more severe (mean vas score . ) than preoperative pain ( . ). myofascial pain syndromes (mps) were diagnosed in . % of patients; neuropathic abnormalities associated or not with mps were found in . %. drug therapy associated with physical medicine treatment provided ≥  % pain im- provement in . % of cases; trigger point injection in . %, and epidural infusion of morphine with lidocaína in . % of refractory cases. conclusion: in patients with a post-laminectomy syndrome, postoperative pain was more severe than preoperative pain from a herniated disk. a miofascial component was found in most patients. keywords: low back pain; intervertebral disk displacement; post-laminectomy syn- drome. study conducted at the pain center, department of neurology, clinical hospital of usp school of medicine, são paulo, sp, brazil submitted on: / / approved on: / / correspondence to: wellingson silva paiva divisão de neurocirurgia funcional e centro de dor hospital das clínicas da faculdade de medicina da usp r. dr. eneas aguiar, º andar – cerqueira césar são paulo – sp cep: - wellingsonpaiva@yahoo.com.br conflicts of interest: none. failed back surgery pain syndrome: therapeutic approach descriptive study in patients manoel jacobsen teixeira , lin tchia yeng , oliver garcia garcia , erich talamoni fonoff , wellingson silva paiva , joaci o araujo lecturer; chair professor in neurosurgery, school of medicine, universidade de são paulo (usp), são paulo, sp, brazil ph.d. in science; pain center coordinator, division of physical medicine, clinical hospital of the school of medicine, usp, são paulo, sp, brazil m.d.; residence in neurosurgery; medical trainee, pain center, clinical hospital of the school of medicine, usp, são paulo, sp, brazil ph.d. in neurology; pain center coordinator, department of neurology, clinical hospital of the school of medicine, usp, são paulo, sp, brazil ph.d. student in neurology; attending physician, pain center and functional neurosurgery, clinical hospital of the school of medicine, usp, são paulo, sp, brazil m.d.; residence in orthopedics; musculoskeletal outpatient clinic coordinator, pain center, clinical hospital of the school of medicine, usp, são paulo, sp, brazil failed back surgery pain syndrome: therapeutic approach descriptive study in patients rev assoc med bras ; ( ): - introduction according to the international association for the study of pain (iasp), the post-laminectomy syndrome is defined as a “low back pain of unknown origin, persisting at the same location as the original pain despite operative interven- tions or with a post-surgery onset. the low back pain may be associated with a referred or radiating pain” . this defi- nition applies to all surgeries designed to treat pain arising from the low back spine, including those aiming to treat a herniated disk. surgical management applied to herniated disks is a hemilaminectomy with a flavectomy, nerve root dislocation and a hernia excision. the many clinical mani- festations of the post-laminectomy pain often overlap and have a low back pain as a common expression. the term “unknown origin” in the definition should not be strictly used, as although the post-laminectomy syndrome is com- plex and the pain can arise from various nosological enti- ties affecting varied anatomical elements in the spine or away from the spine or even being a result from systemic conditions, its origin can be found in many cases . low back pain causes are varied and differential diag- nosis is wide. the structure causing the pain is identified in less than % of cases . the herniated disks are the most common indication for laminectomy to treat low back pain. over thousand laminectomies are estimated to be carried out in the united states, with a failure rate high- er than % . misinterpretation of pain origin as resulting from a herniated disk seen in imaging studies , misidenti- fication of spine instability and other mechanical causes, including incomplete removal of the herniated disk , and operative complications are blamed for the poor surgical results . pain can also result from articular facet instabil- ity or from reduced intervertebral space due to structure abnormalities or intervertebral disk removal, with conse- quent change in the articular facet angle . among non-me- chanical causes for the failed back surgery pain syndrome, disk infection, peridural “fibrosis”, arachnoiditis and psy- chosocial factors should be mentioned . in this study, we aimed to assess the clinical features and the non-surgical management outcome in patients with a failed back sur- gery pain syndrome seen in a pain center. methods fifty-six patients diagnosed with a failed low back surgery pain syndrome were prospectively followed over one year at the neurological clinic pain center of the clinical hos- pital of universidade de são paulo in a descriptive study. the design was approved by the institutional ethics board ( / ). every patient signed an informed consent form. patients with a persisting low back pain or an early relapse within less than three months of a surgical herniated disk procedure were selected. the patients were admitted into a specific postoperative low back pain outpatient clinic according to a spontaneous demand in the unit. patients with evidence of metabolic, inflammatory, and oncologi- cal diseases or a radiological segmental instability picture were excluded. no patients experienced a cognitive im- pairment. out of patients admitted into our unit, were excluded by exclusion criteria and the follow-up was lost in three cases. we obtained data from history, general physical exam, neurological and physiatric evaluation in addition to pre- and postoperative imaging studies. lab- oratory tests to rule out rheumatic or metabolic diseases (ana, rf, esr, crp, blood cell count) were performed. the pain magnitude, characteristic, nature and location, as well as the radiating course in pre- (retrospectively) and postoperative periods. the pain intensity was assessed according to a visual analog scale (vas) before and after treatment. the physiatric exam aimed specially to assess low back spine and paravertebral, low back, gluteal and lower limb muscle groups, consisting of muscle power as- sessment, miofascial trigger point presence, spasms, sen- sitivity, cutaneous changes, and trophism. data collection was performed by using a standard protocol. the statistical analysis used sigmastat software. for all patients, a drug therapy with a rehabilitation program using kinesiotherapy and muscle stretching was adopted and if a rehabilitation refractory myofascial com- ponent (mps) was associated, these patients underwent needling with a % lidocaine injection. mps was identified in ( . %) patients. drug therapy consisted of amitrip- tyline to  mg/day (mean,  mg/day), chlorproma- zine to  mg/day (mean,  mg/day), naproxen to   mg/day (mean  =    mg/day), acetaminophen to   g/day (mean  =  . g/day) and codeine phosphate to  mg/day (mean =   mg/day) according to the requirements and tolerability in each case. all patients un- derwent physiatric follow-up. in case there was not ≥  % original pain improvement (vas) all over the follow-up, the patients were considered frankly refractory, undergoing a  ml infusion containing morphine   mg/ml and % lidocaine by catheter place- ment into the low back peridural compartment bid over two weeks. results overall, ( . %) patients were male and their ages ranged from to years (mean, . years ±  . years). the patients’ mean age at the original pain onset ranged from to years (mean =  . years). the patients had undergone from one up to four low back laminectomies (mean =  . ) to treat low back pain or lumbosciatic pain. the mean symptomatology length was months. the length of the low back pain or lumbosciatic pain complaints ranged from to months (mean  =  months). regarding the pain intensity, the patients with a radiculopathy persisting postoperatively were found with a higher pain score by the pain analog scale. those manoel jacobsen teixeira et al. rev assoc med bras ; ( ): - muscle n % lumbar quadrate gluteus medius gluteus minimum piriform total n, absolute numbers; %, percentage. table – patient disposition according to muscles affected more severely by the myofascial pain syndrome muscle n % gluteus medius gluteus minimum lumbar quadrate , piriform , vastus lateralis vastus medialis gastrocnemius levator ani mps, myofascial pain syndrome table – affected muscle distribution by mps satellite or secondary trigger points with a postoperative root pain diagnosed had a mean score of . , compared with . for those with no radiculopathy (p =  . ). in ( . %) patients, the preoperative pain history was consistent with a root origin, in ( . %) with re- ferred pain in musculoskeletal conditions in both lower limbs, in ( , %) with referred pain in one lower limb, in ( . %), the pain location was only the lower back re- gion and in ( . %) the pain had polyneuropathy char- acteristics. three ( . %) patients who did not experience pain with root characteristics preoperatively had under- gone a diskectomy and spinal fixation. x-ray studies disclose a one- or two-lumbar-segment hemilaminectomy unilaterally (l or l ) in ( . %) pa- tients and bilateral lumbar laminectomy in ( . %). the lumbar spine dynamic study did not show instability in any patient. the computed tomography (ct) scan or mag- netic resonance (mr) imaging did reveal a periradicular scar at the operative site in ( . %) cases. the pain intensity before the operations ranged from moderate to severe, according to the vas, scoring from to (mean =  . ); the pain intensity at the first attendance to the pain center, clinical hospital, universidade de são paulo was severe, scoring from to (mean =  . ). thirty-six patients ( . %) had undergone physical therapy, ( . %) had been on nonsteroidal anti-in- flammatory drugs (nsaids), and ( . %) had been on corticosteroids alone or in combination with b complex vitamins, four ( . %) had been on opiates, and five ( . %) had been on tricyclic antidepressive agents before and af- ter the surgery. all of the patients had stayed at rest and those exerting an occupational activity had been put away from work. in ( . %) patients, uniradicular ( . %) or mul- tiradicular ( . %) syndromes were shown. ten ( . %) patients had muscle pain and myofascial painful points in several body regions, sleep disturbances and depression, suggesting the fibromyalgia syndrome. trigger points characteristic of mpss were identified in ( . %) patients. out of ( . %) patients with preoperative nerve root pain, ( . %) had lumbar or gluteal mpss (table  ). satellite or secondary trigger points were found in ( . %) patients (table  ). the treatment outcome was rated as excellent (>  % improvement over the original pain according to the vas), good ( % to % improvement), fair ( % to <  % im- provement) and poor (<  %). drug therapy combined with physical rehabilitation measures provided an excellent outcome in ( . %) pa- tients, a good outcome in ( . %), a fair outcome in ( . %) and a poor outcome in ( . %). in patients, mps was found and trigger point in- jections were performed by using % lidocaine .   ml. by comparing the pain improvement scores, patients with mps had worse outcomes over post-laminectomy syn- drome without mps. the immediate results were excellent in ( . %), good in ( . %), fair in ( . %) and poor in ( . %). the results were satisfactory for . % of patients with mps versus % in patients without mps, but the difference was not statistically significant (p =  . ). at the end of treatment, significant improvement (ex- cellent and good outcomes) occurred in ( . %) pa- tients, while ( . %) had a fair outcome. however, the outcome was considered poor in ( . %) patients. re- garding the pain intensity at the final follow-up, we found a reduced general mean in the visual analog scale from . to . (p =  . ). a peridural catheter for spinal infusion of a morphine and lidocaine solution was placed in thirteen patients; all of them had a mps, being considered refractory after a re- habilitative treatment attempt. the outcome was excellent in ( . %) patients, good in ( . %), and poor in ( . %), meaning the outcome was excellent or good in ( . %) patients treated with a peridural infusion. discussion low back pain is present at some point in life and con- stitutes a serious public health problem in % to % of individuals . treatment cost, compensation, and lost pro- ductivity are high. the patients’ mean age at pain onset was . years, with the individuals within this age group usu- ally exercising their occupational activity to a very great extent. failed back surgery pain syndrome: therapeutic approach descriptive study in patients rev assoc med bras ; ( ): - in most cases, the course is favorable, even when no care measures are taken. however, low back pain becomes chronic in % to % of individuals . in . % of patients studied by frymoyer , the pain lasted more than two weeks and in % it was severe. in . % of deyo and tsiu’s patients , the pain was mild; in . %, it was moderate and in %, severe; in % of cases, the low back pain irradi- ated to lower limbs and in only % a true sciatic pain could be found. in our series, preoperative pain was severe, with a . score according to the vas; . % had a low back pain and referred pain to lower limbs history before the surgery. in only . %, the history suggested a true sciatic pain, and these findings indicate selection criteria for the surgery were likely inappropriate in most cases. according to hanley et al. , the operative treatment outcome of herniated disks is poor in % of cases. the numbers of spine surgeries to relieve pain have steadily grown in the united states, with thousand operations in , , in reaching , in , with thousand cases of failed back surgery pain syndrome per year . according to deyo and tsiu , the main reason for an increasing number of laminectomies is the growing number of surgeons operating the spine in each country. in different countries and different regions, the frequency of operation indications is variable, and this is not ex- plained only by the different prevalence of low back pain or lumbosciatic pain; in % or % of individuals, herniated disk surgeries are indicated in the usa, but only in % of individuals in sweden and denmark. poor outcome of operative treatment might result from an incorrect diagnosis. among the identified causes for low back pain, the following could be highlighted: rheu- matic conditions, primary or secondary spine tumors, vascular conditions, hematological abnormalities, en- docrine conditions, pelvic or abdominal viscus diseases (endometriosis, ovarian cyst torsion, pelvic inflammatory disease, prostatitis, cystitis,  pancreatopathy, nefropathy, kidney disease, peptic ulcer, urinary tract, biliary or duo- denal conditions), mechanical abnormalities (herniated in- tervertebral disk, articular facet injury, segmental instability or sacroiliac joint instability), systemic conditions (fibromy- algia, myositis, autoimmune or immune-allergic diseases), psychiatric diseases and other conditions (hip joint disease, trochanteric bursa injury, polyradiculoneuritis, meningeal irritation signs) . because of the great number of possibili- ties, the high surgical therapeutic failure rate is justifiable in care provided to these patients, but it also indicates there must be a more judicious semiologic evaluation. surgeries that do not meet the indication criteria to treat a herniated disk can result in maintenance or wors- ening of pain and preoperative deficits. a herniated disk misinterpreted as a cause for low back pain is the most common reason for indicating spine surgeries that prog- ress to a post-laminectomy chronic pain syndrome with an early onset postoperatively. this is partly due to over- valuing the anatomical findings not related to the low back pain that are shown in imaging studies, but those usually do not warrant the pain and the surgical intervention . in % of asymptomatic individuals studied by hitselberg and wihen , the x-ray imaging revealed abnormalities suggesting a herniated disk. in % of asymptomatic in- dividuals studied by wiesel et al. , a spine ct scan found abnormalities; in . % of cases, there was a herniated disk evidence. boden et al. observed % of asymptomatic in- dividuals had a herniated disk on magnetic resonance im- aging. therefore imaging studies can confirm a herniated disk clinical diagnosis, but they are not the main determi- nants for indicating a surgery, since asymptomatic herni- ated disks are so commonly seen . even in symptomatic conditions, there is a progressive absorption of the herniated disk fragment, a phenomenon accompanied by symptom improvement in most cases . hakelius observed % of patients with a herniated disk not undergoing a surgery, but having been on medical treatment, were clinically improved within a month, % within two months, and % within three months. saal and sall conducted a retrospective study involving patients with a radiculopathy resulting from a herniated disk; underwent a conservative treatment, resulting in improvement in over % of cases; only in three cases surgical ablation of extruded fragments was required. this means the indication criteria for diskectomy, represented by a cauda equina syndrome, marked acute or progressive motor deficit or lumbosciatic pain occurrence and evident radiculopathy, characterized by sensory, motor and deep tendon reflexes deficits over one or more nerve root ter- ritory, nerve root irritation evidence, translated as a posi- tive straight leg raising maneuver and consistent imaging study findings in patients achieving no improvement after symptomatic drug therapy with physical medicine measures during a period of over to weeks , , are not always met. only . % of patients included in the current casuistry had undergone physical medicine treatment and only . % had undergone a tricyclic antidepressant thera- py before the operations, suggesting medical methods had not been adopted in most cases. mechanical causes are responsible for % of post-lam- inectomy pain cases . among them, residual or relapsed herniations, spinal instability, post-vertebral fixation pseud- arthrosis, articular facet abnormalities, spinal canal stenosis, meningocele and pseudomeningocele are highlighted . in no patient of ours a spinal instability or residual herniation was found. in addition to the diskectomy, a spinal fixation and fusion was proposed . however, there is little evidence the spinal fusion is useful in patients with no actual spinal instability . this occurred in . % of study subjects. postop- erative imaging of a residual disk herniation does not imply this is necessarily the cause for a persisting pain, as postop- manoel jacobsen teixeira et al. rev assoc med bras ; ( ): - erative imaging studies often show similar abnormalities in individuals whether they are symptomatic or not . peridu- ral scar occurring after a laminectomy is a frequent post- operative finding. newly formed tissue can involve, distort and/or compress the nerve root. however, epidural fibrosis is often shown on ct scan or mri postoperatively in cases there is no pain . in . % of patients in this study, a perira- dicular scar was found. the patients included in our study had undergone up to surgical lumbar spine surgical procedures with no im- provement; the mean was . operations per patient. many patients undergoing further operations to treat persisting or residual pain get frustrated. the improvement rate in reoperations is low, around % after the second surgery, % after the third surgery and % after a fourth proce- dure with up to % of worsening . out of patients analyzed in the present study, , % had mps not found previously on physical exam. there is evidence that mps is involved in low back pain genesis or maintenance . however, mps diagnosis is frequently dis- regarded . many lumbar muscles affected by mps and the operative injury would result in pain worsening. although physiatrically speaking lumbar and gluteal muscle mps is considered the most important cause for low back pain, bone, tendinous, nerve, disk and bursa conditions are still valued as symptom causes . the muscle fiber injury is not necessarily a cause for pain, since in patients with primary degenerative conditions, as in duchenne muscular dystro- phy, there is a disruption in a large amount of myofibrils and the sarcoplasmic reticulum, but there is no pain, sug- gesting mps symptoms result from nonstructural muscle fiber changes or dysfunctions . the main electrophysio- logical abnormality seems to be a neuromuscular dysfunc- tion in the motor endplate. the energy crisis theory postulates there is an increased calcium concentration in the sarcoplasm due to a sarco- plasmic reticulum, sarcolemma and or muscle cell mem- brane disruption. the sarcoplasmic reticulum function is storing and releasing ionized calcium, which activates contractile elements and causes sarcomere shortening. sustained sarcomere contraction results in increased me- tabolism, causes localized ischemia and generates a local- ized energy crisis. the combination of electrophysiological and histopathological theories generated the neuromus- cular endplate multiple dysfunction concept. the poten- tials recorded as spontaneous activity or spikes in trigger points would result in abnormal acetylcholine release by the nervous ending. acetylcholine release would accentu- ate depolarization and calcium release from the sarcoplas- mic reticulum, causing sarcomere contraction and small- caliber vessel compression. increased depolarization due to acetylcholine release and sarcomere contraction would cause increased energy demand, which, if associated with hypoxia resulting from reduced muscle blood flow, would then cause the energy crisis. this energy crisis generates metabolites which sensitize nociceptores and referred pain from trigger points . the abnormalities in nerve fibers re- sponsible for supplying the muscle could cause localized muscle contraction and mps . the referred pain from the trigger point is due to a sensory neuron sensitization in the spine cord posterior horn and may have a distribution similar to that in the radiculopathic pain. this referred pain associates with tingling and numbness . in . % of patients with preoperative nerve root pain history, lum- bar and gluteal mps was identified. the ages of patients included in the study when firstly seen at the pain center ranged from to years (mean age, . years). the mean symptom length was months and the mean pain intensity was . , showing the magni- tude and the extended distress the patients went through. the postoperative pain was also shown more severe than the preoperative pain. the chronic pain treatment should involve a multi- disciplinary team and pharmacological, physiatric, psy- chotherapeutic, and neuroanesthesic procedures; func- tional neurosurgical procedures should be performed if required . the treatment with analgesic drugs, whether they are anti-inflammatory drugs or not, psychotropic drugs and physical medicine provided >  % original pain improvement in . % of patients evaluated in this study. myofascial trigger point treatment consists of using analgesic drugs, psychotherapeutic agents, muscle relax- ant drugs, refrigerant vapor, dry needling, local anesthetic injection and stretching, as well as correction of causal or perpetuating factors . in . % of patients undergoing administration of a morphine and lidocaine solution via peridural route in our study, the original pain had >  % improvement. the pain in patients with failed back surgery pain syn- drome is severe, affects individuals in the fullness of their activities, is often found as a lumbar and/or gluteal mps and, less frequently, has a neuropathic pattern alone or as- sociated with mpss . conclusion the failed back surgery pain syndrome evaluation and management is challenging for the medical team. analgesic drugs and physical medicine provide major improvement in most cases. the pain intensity in post-laminectomy syn- drome is worse than the herniated disk preoperative pain. the injection of myofascial trigger points and opiate infu- sion into the lumbar spine compartment can be required in refractory pain cases. references . merskey nb. classification of chronic pain: descriptions of chronic pain syndromes and definitions of pain terms prepared by the in- ternational association for the study of pain. nd ed. seattle: iasp press; 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: - . . rachlin es. importance of trigger point management in orthopedic practice myofascial pain update in diagnosis and treatment. phys med rehabil clin north am. ; : - . . cannon de, dillingham tr, miao h, andary mt, pezzin le. mus- culoskeletal disorders in referrals for suspected lumbosacral radicu- lopathy. am j phys med rehabil. ; : - . . teixeira mj. princípios de tratamento da dor. in: teixeira mj, figue- iró jab, editors. dor, epidemiologia, fisiopatologia, avaliação, sín- dromes dolorosas e tratamento. são paulo: grupo editorial moreira jr; . p. - . . lin ty, kazyiama hhs, teixeira mj. síndrome dolorosa miofascial. rev medicina ; ( ): - . lipid droplets and lipotoxicity during autophagy uc berkeley uc berkeley previously published works title lipid droplets and lipotoxicity during autophagy. permalink https://escholarship.org/uc/item/ gv q j journal autophagy, ( ) authors nguyen, truc olzmann, james publication date doi . / . . peer reviewed escholarship.org powered by the california digital library university of california https://escholarship.org/uc/item/ gv q j https://escholarship.org http://www.cdlib.org/ autophagic punctum lipid droplets and lipotoxicity during autophagy truc b. nguyen and james a. olzmann department of nutritional sciences and toxicology, university of california, berkeley, berkeley, ca, usa article history received july revised july accepted july abstract lipid droplets (lds) are neutral lipid storage organelles that provide a rapidly accessible source of fatty acids (fas) for energy during periods of nutrient deprivation. surprisingly, lipids released by the macroautophagic/autophagic breakdown of membranous organelles are packaged and stored in new lds during periods of prolonged starvation. why cells would store fas during an energy crisis was unknown. in our recent study, we demonstrated that fas released during mtorc -regulated autophagy are selectively channeled by dgat (diacylglycerol o-acyltransferase ) into triacylglycerol (tag)-rich lds. these dgat -dependent lds sequester fas and prevent the accumulation of acylcarnitines, which otherwise directly disrupt mitochondrial integrity. our findings establish ld biogenesis as a general cellular response to periods of high autophagic flux that provide a lipid buffering system to mitigate lipotoxic cellular damage. keywords acylcarnitine; autophagy; dgat ; lipid droplets; lipotoxicity; mitochondria; mtorc lds are conserved, endoplasmic reticulum (er)-derived organ- elles found in nearly every cell type. lds consist of a core of neutral lipids (tags and cholesteryl esters) encircled by a phospholipid monolayer that is decorated with integrally and peripherally associated regulatory proteins. this specialized ultrastructure enables lds to function as dynamic lipid storage depots that are highly responsive to the cellular metabolic state. during starvation, ld-associated neutral lipid lipases (e.g., pnpla /atgl [patatin like phospholipase domain containing ]) mediate the breakdown of lds, liberating fas from stored tags for the generation of energy in mitochondria via b-oxi- dation. unexpectedly, during periods of prolonged starvation, it was found that fas released by the autophagic breakdown of membranous organelles are packaged into new lds. however, why cells would expend energy to synthesize and store tags in lds during an energy crisis was a mystery. consistent with the previous report, starvation of mouse embryonic fibroblasts in hank’s balanced salt solution (hbss) leads to an increase in lds. these lds are highly clustered and in close proximity to mitochondria, potentially forming mem- brane contact sites to facilitate ld-mitochondrial fa transfer. starvation-induced increase in lds is observed in multiple cell lines (u os, hela, huh ) and can be blocked by inhibitors of autophagy and lysosomal function (e.g., bafilomycin a and - methyladenine), but not by inhibitors of fasn (fatty acid syn- thase; e.g., tvb- ). mechanistic target of rapamycin com- plex (mtorc ) is a master regulator of cell growth that inhibits autophagy in the presence of growth factors and adequate nutrients. inhibition of mtorc with the small molecule inhibitor torin or by deletion of the gene encoding the ragulator subunit lamtor /p is sufficient to increase autophagic flux and autophagy-dependent ld biogenesis, even in nutrient-rich complete medium (cm). conversely, constitu- tive activation of mtorc by deletion of the gene encoding nprl , a subunit of the gator complex, blocks starvation- induced ld biogenesis. thus, mtorc -regulated autophagy is sufficient to induce ld biogenesis and is necessary for ld biogenesis during starvation. these data suggest that ld biogenesis is a general cellular response to periods of high autophagic flux. to understand the function of lds during starvation, we first examined the enzymes required for ld biogenesis during periods of nutrient excess (i.e., oleate-treated) and nutrient dep- rivation (i.e., hbss). the final and committed step in tag syn- thesis is mediated by the diacylglycerol acyltransferase enzymes dgat and dgat . in the presence of oleate, ld biogenesis is only partially blocked by dgat or dgat inhibition alone, and complete blockade of ld biogenesis requires simultaneous inhibition of both enzymes. in contrast, inhibi- tion of dgat , but not dgat , is sufficient to prevent ld biogenesis under starvation conditions. the inhibition of dgat does not affect lc degradation kinetics or autophagic flux, indicating that the impairment of ld biogenesis is not due to disruption of autophagy (i.e., the source of fas). although dgat and dgat share tag synthesis activity, our results demonstrate that the functions of these enzymes are not redundant and that dgat is specifically required for ld biogenesis during starvation. contact james a. olzmann olzmann@berkeley.edu department of nutritional sciences and toxicology, university of california, berkeley, morgan hall room , berkeley, ca – , usa. punctum to: nguyen tb, louie sm, daniele j, tran q, dillin a, zoncu r, nomura dk, olzmann ja. dgat -dependent lipid droplet biogenesis protects mitochondrial function during starvation-induced autophagy. developmental cell; , - . pmid: . https://doi.org/ . /j.devcel. . . © truc b. nguyen and james a. olzmann. published with license by taylor and francis. this is an open access article distributed under the terms of the creative commons attribution-noncommercial-noderivatives license (http://creativecommons.org/licenses/by-nc-nd/ . /), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way. autophagy , vol. , no. , – https://doi.org/ . / . . https://crossmark.crossref.org/dialog/?doi= . / . . &domain=pdf&date_stamp= - - mailto:olzmann@berkeley.edu https://doi.org/ . /j.devcel. . . http://creativecommons.org/licenses/by-nc-nd/ . / https://doi.org/ . / . . the ability to block ld biogenesis with an inhibitor of dgat provides a useful tool to probe the functional importance of lds during starvation conditions. employing single reaction monitoring (srm)-based lc-ms steady-state lipidomic profiling and isotopic palmitate tracing, we found that dgat inhibition has little effect on the cellular lipid landscape in cm. indeed, tag levels are unaffected by dgat inhibition, indicating that dgat is not necessary to maintain tag pools in cm. in sharp contrast, dgat inhibition during hbss starvation results in a dramatic reduction in nearly all tag species as well as a concomi- tant increase in the levels of acylcarnitines, which are important fa-conjugates that are formed at the mitochon- dria and are required for fa transport into the mitochon- drial matrix for b-oxidation. the accumulation of acylcarnitine suggests that the loss of lds could affect mitochondrial function. indeed, our results revealed that dgat inhibition during starvation significantly reduces basal mitochondrial oxygen consumption rates, mito- chondrial membrane potential, and cellular viability. the mor- phology and overall abundance of mitochondria is unaltered by dgat inhibition, indicating that the decrease in mitochon- drial functional parameters is not due to increased mitophagy or reduced mitochondrial biogenesis. surprisingly, reducing acylcarnitine levels with the cpt inhibitor etomoxir rescues mitochondrial membrane potential in starved cells treated with dgat inhibitor. furthermore, treating isolated mitochondria with palmitoylcarnitine is sufficient to depolarize the mito- chondria. these data implicate acylcarnitine as the lipotoxic culprit that directly disrupts mitochondrial function in the absence of lds. we did not observe other lipotoxic lipidomic signatures, such as the accumulation of ceramide or an alter- ation in the ratio of phosphatidylethanoamine to phosphatidyl- choline, and there is no observable activation of the er unfolded protein response. thus, our data suggest that dgat -dependent ld biogenesis during starvation is required to prevent the accumulation of acylcarnitines, which directly cause selective lipotoxic mitochondrial dysfunction. in conclusion, our findings establish a novel function for lds in preventing lipotoxic cellular damage during auto- phagy (figure ). an important future goal will be to under- stand the importance of lds and lipotoxicity in physiological conditions associated with high autophagic flux (e.g., cancer and neurodegeneration). orcid james a. olzmann http://orcid.org/ - - - disclosure of potential conflicts of interest no potential conflicts of interest were disclosed. funding this research was supported by grants from the national institutes of health (r dk and r gm to j.a.o) and from the american heart association ( grnt to j.a.o.). t.b.n was supported by a training grant from the nih (t dk ). figure . lipid droplets protect against lipotoxicity during autophagy. during prolonged starvation (e.g., amino acid depletion), mtorc is inactivated and autophagy is upregulated. (a) autophagic breakdown of membranous organelles releases fas that are channeled into dgat -dependent lds. the fas can be liberated from lds by ld-associated lipases (e.g., pnpla /atgl) and transferred to mitochondria for b-oxidation. (b) in the absence of ld biogenesis, such as during inhibition of dgat , auto- phagy-released fas can no longer be sequestered as tags and instead accumulate as acylcarnitine (ac), which disrupts mitochondrial membrane integrity and impairs mitochondrial function. autophagy http://orcid.org/ - - - 	abstract 	disclosure of potential conflicts of interest 	funding . seaton a, godden dj, brown k. increase in asthma: a more toxic environment or a more susceptible population? thorax ; : – . . holgate st. the epidemic of allergy and asthma. nature ; ( suppl): b –b . . holt pg, macaubas c, stumbles pa, sly pd. the role of allergy in the development of asthma [review]. nature ; : b –b . . strachan dp, harkins ls, johnson id, anderson hr. childhood ante- cedents of allergic sensitization in young british adults. j allergy clin immunol ; : – . . ishizaka k, ishizaka t, hornbrook mm. physico-chemical properties of human reaginic antibody. iv. presence of a unique immunoglobulin as a carrier of reaginic activity. j immunol ; : – . . prescott sl, macaubas c, smallacombe t, holt bj, sly pd, loh r, holt pg. reciprocal age-related patterns of allergen-specific t-cell immunity in normal vs. atopic infants. clin exp allergy ; : – . . miles ea, warner ja, jones ac, colwell bm, bryant tn, warner jo. peripheral blood mononuclear cell proliferative responses in the first year of life in babies born to allergic parents. clin exp allergy ; : – . . platts-mills tae, woodfolk ja. cord blood proliferative responses to inhaled allergens: is there a phenomenon? [editorial]. j allergy clin immunol ; : – . . rowntree s, cogswell jj, platts-mills tae, mitchell eb. development of ige and igg antibodies to food and inhalant allergens in children at risk of allergic disease. arch dis child ; : – . . sporik r, squillace sp, ingram jm, rakes g, honsinger rw, platts-mills tae. mite, cat and cockroach exposure, allergen sensitization, and asthma in children: a case-control study of three schools. thorax ; : – . . hasselmar b, aberg n, aberg b, eriksson b, bjorksten b. does early exposure to cat or dog protect against later allergy development? clin exp allergy ; : – . . svane c, jarvis d, chinn s, burney p. childhood environment and adult atopy: results from the european community respiratory health survey. j allergy clin immunol ; : – . . platts-mills t, vaughan j, squillace s, woodfolk j, sporik r. sensitisation, asthma, and a modified th response in children exposed to cat allergen: a population-based cross-sectional study. the lancet ; : – . . fredburg jj, inouye ds, mijailovich sm, butler jp. perturbed equilibrium of myosin binding in airway smooth muscle and its implications in bronchospasm. am j resp crit care med ; : – . . skloot g, permutt s, togias a. airway hyperresponsiveness in asthma. j clin invest ; : – . . luder e, melnik ta, dimaio m. association of being overweight with greater asthma symptoms in inner city black and hispanic children. j peds ; : – . . camargo ca, weiss st, zhang s, willett wc, spetzer fe. prospective study of body mass index, weight change, and risk of adult-onset asthma in women. arch intern med ; : . . platts-mills tae, woodfolk ja, chapman md, heymann pw. changing concepts of allergic disease: the attempt to keep up with real changes in lifestyles [review]. j allergy clin immunol ; : s –s . atopic dermatitis: a paradigmatic allergic skin disease thomas bieber department of dermatology, friedrich-wilhelms-university, sigmund-freud-stra be , d- bonn, germany tel: + fax: + e-mail: thomas.bieber@meb.uni-bonn.de introduction atopic dermatitis (ad) is a chronic inflammatory skin disease clinically and histologically highly similar to allergic contact dermatitis. recently, it has been proposed to subdivide ad into two distinct forms: the extrinsic form (occurring in the context of sensitiza- tion toward environmental allergens), and the intrin- sic form (occurring in the absence of any typical atopical background). while the pathophysiology of the intrinsic form remains almost elusive, tremendous progress has been made in the understanding of the extrinsic form. thus, since ige plays a major role in other atopic diseases such as asthma and rhinitis, it is assumed that, in this extrinsic form, immunoglobulin e (ige) also mediated the specificity of the inflamma- tory conditions in the skin. presence of ige-bearing dendritic cells in the skin of patients with ad the emergence of extrinsic ad (i.e. a cell-mediated inflammation) in atopic patients (i.e. individuals prone to have increased ige production and to develop ige-mediated hypersensitivity reactions) remained puzzling until the mid- s, when the presence of ige molecules on the surface of langer- hans cells (lc) from patients presenting ad was first reported. , a new pathophysiological concept was proposed in which lc and inflammatory dendritic epidermal cells (idec) armed with allergen-specific ige would trigger an eczematous inflammation. molecular structure, regulation and function of fc«ri on human dendritic cells the identity of the relevant ige-binding structure of cutaneous dendritic cells (dc) was unclear for some years, until other workers and myself demonstrated the presence of the high-affinity receptor for ige (fc«ri) on these cells as well as on other antigen presenting cells (apc), including monocytes, and circulating dc. – it also became clear that fc«ri on apc lacks the classical b-chain and thus, in contrast to effector cells of anaphylaxis (i.e. mast cells and basophils that express an a,b,g conformation), apc display an a,g conformation that implies profound functional consequences. moreover, its expression and the function may be highly variable, depending on the microenvironment. however, the highest expression is specifically observed in ad skin. one may speculate that fc«ri ligation on apc putatively triggers the synthesis and release of mediators that may initiate a local inflammatory reaction, as has been demonstrated for mast cells. fc«ri/ige-mediated allergen uptake and subsequent antigen presentation has been attributed a key event in the pathogenesis of atopic dermatitis. using this kind of antigen uptake, apc may, in the presence of antigen- specific ige, increase their presenting capacity up to -fold. this mechanism, also known as ‘antigen focusing’ or ‘facilitated antigen presentation’, has been shown effective by different research groups in different cell systems. the observation that the mini reviews mediators of inflammation · vol · presence of fc«ri-expressing lc/idec, bearing ige molecules, is a prerequisite to provoking eczematous lesions, observed after application of aeroallergens to the skin of atopic patients, strongly supports this concept. thereby, ige receptors are the connecting link between the specificity gaining ige molecules and the apc. however, fc«ri seems to play the major role in these phenomena. it should be noted that fc«ri expressed on circulating monocytes may have other functions, mainly in regulating their survival and differentiation outcome. following the presentation of allergens to t cells, allergen-specific b cells may be activated to produce high amounts of allergen-specific ige. this ige may then in turn bind to the fc«ri on the apc, closing a vicious circle of facilitated antigen presentation. the intermittent or continuous supply of aeroallergens or autoantigens to the process of facilitated antigen presentation may define the pathophysiological basis of the recurrent or self-perpetuating course of ad frequently seen in untreated patients. the successful application of aeroallergens such as cat dander in the recently standardized atopy patch test shows that it is possible to elicit eczematous skin lesions by solely external application of aeroallergens to the skin. based on the facilitated antigen presentation model of ad, the need for an identification of the individual provocation factors in each patient calls for diagnostic procedures based on the allergen-specific ige. cat dander, house dust mite allergens and a variety of food allergens may be successfully avoided following a thoroughly undertaken prick test and in vitro ige diagnostic evaluation. conclusion consequently, ad may represent a paradigm of ige/ fc«ri-mediated, delayed-type hypersensitivity reac- tion. a similar role could be attributed to other fc«ri- expressing dc in the lung, where such cells may also be considered as putative targets for new therapeutic strategies. references . wüthrich b. neurodermitis atopica. wien med wochenschr ; : – . . bruijnzeel-koomen c, van wichen df, toonstra j, et al. the presence of ige molecules on epidermal langerhans cells in patients with atopic dermatitis. arch dermatol res ; : – . . bieber t, dannenberg b, prinz jc, rieber ep, stolz w, ring j, braun-falco o. occurence of ige bearing langerhans cells in atopic eczema: a study of the time course and with regard to the ige serum level. j invest dermatol ; : – . . wollenberg a, kraft s, hanau d, bieber t. immunomorphological and ultrastructural characterization of langerhans cells and a novel, inf lam- matory dendritic epidermal cell (idec) population in lesional skin of atopic eczema. j invest dermatol ; : – . . bieber t, de la salle h, wollenberg a, et al. human epidermal langerhans cells express the high affinity receptor for immunoglobulin e (fc epsilon ri). j exp med ; : – . . wang b, rieger a, kilgus o, et al. epidermal langerhans cells from normal human skin bind monomeric ige via fceri. j exp med ; : – . . maurer d, fiebiger e, reininger b, et al. expression of functional high affinity immunoglobulin e receptors (fc epsilon ri) on monocytes of atopic individuals. j exp med ; : – . . jürgens m, wollenberg a, de la salle h, hanau d, bieber t. activation of human dendritic langerhans cells by engagement of the high affinity receptor for ige fc«ri. j immunol ; : – . . wollenberg a, wen s, bieber t. langerhans cell phenotyping: a new tool for differential diagnosis of inflammatory skin diseases. lancet ; : – . . bieber t. fc«ri-expressing antigen-presenting cells: new players in the atopic game. immunol today ; : – . . maurer d, ebner c, reininger r, fiebiger e, kraft d, kinet jp, stingl g. the high affinity ige receptor (fc«ri) mediates ige-dependent allerge n presentation. j immunol ; : – . . katoh n, kraft s, wessendorf jh, bieber t. the high-affinity ige receptor (fcepsilonri) blocks apoptosis in normal human monocytes. j clin invest ; : – . . darsow u, vieluf d, ring j. atopy patch test with different vehicles and allergen concentrations: an approach to standardization. j allergy clin immunol ; : – . mini reviews mediators of inflammation · vol · why is the prevalence of allergic diseases increasing? a critical assessment of some classical risk factors denis charpinca and marion gouitaa department of chest diseases & allergy, hospital north, marseille, france c a corresponding author tel: + fax: + e-mail: dcharpin@ap-hm.fr introduction many epidemiological surveys, among which repeated cross-sectional surveys have most validity, have demonstrated a twofold increase in the preva- lence of allergic and asthma during the past two decades. , the next presentations will deal with newly- identified or suspected risk factors such as repeated childhood infections, the role of the gut flora and the potential protective effect of contact with farm animals. in this paper, we review some risk factors whose responsibility is often given for granted but which do not actually appear to play a major role in the increase of allergic diseases, namely allergen exposure, air pollution and passive smoking. allergen exposure among allergens, house-dust mites have been advo- cated to be responsible for the increasing trend in the prevalence of allergic diseases. we will present the pros and cons of this hypothesis. d because of the worldwide energy crisis in the s, there has been a large decrease in the ventilation rate of private houses in western countries, which could have led to multiplication of house-dust mites. actually, there is a single study supporting this latter statement. another hypoth- submit your manuscripts at http://www.hindawi.com stem cells international hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume mediators inflammation of hindawi publishing corporation http://www.hindawi.com volume behavioural neurology endocrinology international journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume disease markers hindawi publishing corporation http://www.hindawi.com volume biomed research international oncology journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume oxidative medicine and cellular longevity hindawi publishing corporation http://www.hindawi.com volume ppar research the scientific world journal hindawi publishing corporation http://www.hindawi.com volume immunology research hindawi publishing corporation http://www.hindawi.com volume journal of obesity journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume computational and mathematical methods in medicine ophthalmology journal of hindawi publishing corporation http://www.hindawi.com volume diabetes research journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume research and treatment aids hindawi publishing corporation http://www.hindawi.com volume gastroenterology research and practice hindawi publishing corporation http://www.hindawi.com volume parkinson’s disease evidence-based complementary and alternative medicine volume hindawi publishing corporation http://www.hindawi.com _ introduction traumatic brain injury (tbi) occurs when a traumatic event causes the brain to move rapidly within the skull, leading to damage. as illustrated in the poster (panel a), the event can be classified as either impact or non-impact, depending on whether the head makes direct contact with an object (impact) or encounters a non- impact force such as blast waves or rapid acceleration and deceleration (non-impact). a tbi occurs every  seconds in the us, generating . million new head injury victims per year. these events are responsible for , deaths, leave , individuals with permanent disabilities and cost more than us$ billion on average per year (faul et al., ). the frequency of brain injury is currently higher than that of any other disease, including complex diseases such as breast cancer, aids, parkinson’s disease and multiple sclerosis. the magnitude of the tbi epidemic is matched only by the sheer complexity of the cerebral pathophysiology involved. injury severity, type and location, and the individual’s age and gender, all contribute to producing unique brain pathologies, meaning that no two tbis are the same. age and injury severity are particularly important in determining outcome. falls ( %) and motor-vehicle or traffic-related accidents ( %) are the leading causes of moderate to severe tbi in the us (faul et al., ). the incidence of sport-related concussions is estimated to be , per year among children - years of age (cohen et al., ). among active military personnel, blast injury is the most common cause of tbi (elder and cristian, ). currently, the severity of tbi is categorized based on the glasgow coma scale (gcs), in which patients are scored on the basis of clinical symptoms, and the resulting overall score classifies their injury as mild (score: - ), moderate (score: - ) or severe (score: < ). symptoms of mild to moderate tbi can include headaches, dizziness, nausea and amnesia; these injuries usually resolve within days to weeks of the insult. however, occasionally these injuries can result in long-term cognitive and behavioral deficits. furthermore, there is evidence to suggest that moderate to severe tbi, and even repeat mild tbi, might be associated with increased risk of neurodegenerative diseases such as alzheimer’s disease (lye and shores, ), chronic traumatic encephalopathy (mckee et al., ) and parkinson’s disease (hutson et al., ). to study tbi pre-clinically, researchers have developed several experimental animal models to replicate human pathophysiology. tbi models are used to study aspects of primary and secondary brain injury. primary injury refers to the initial impact that causes the brain to be displaced within the skull. secondary injuries gradually occur as a consequence of ongoing cellular events that cause further damage. fluid percussion (fp), controlled cortical impact (cci) and weight-drop injury are the most commonly used tbi models that can be modulated to generate injuries with characteristics of mild or severe tbi [table and discussed in more detail in namjoshi et al. (namjoshi et al., )]. fp injury is generated by rapid injection of saline through a craniotomy into the epidural space, which causes the brain to move within the skull. cci injury is produced by the rapid compression of brain tissue by an air-driven piston through a craniotomy. the region of damaged cells within the compressed brain tissue dies, generating a contusion core, which usually develops within days after injury. finally, the weight-drop model involves the release of a weight from a known height directly onto the closed skull to produce general movement of the brain. all these models can be adjusted to provide various injury severities and the distinct pathophysiology can vary in different models. despite the overwhelming number of potential permutations for tbi, research has revealed several characteristic physiological responses common to tbi, which are summarized in this review and in the accompanying poster. at a glance disease models & mechanisms disease models & mechanisms , - ( ) doi: . /dmm. the pathophysiology of traumatic brain injury at a glance mayumi prins , , ,*, tiffany greco , daya alexander , and christopher c. giza , , department of neurosurgery, ucla, los angeles, ca , usa the interdepartmental program for neuroscience, ucla, ca - , usa the ucla brain injury research center, los angeles, ca - , usa department of neurology, ucla, los angeles, ca , usa *author for correspondence (mprins@mednet.ucla.edu) © . published by the company of biologists ltd this is an open access article distributed under the terms of the creative commons attribution license (http://creativecommons.org/licenses/by/ . ), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed. traumatic brain injury (tbi) is defined as an impact, penetration or rapid movement of the brain within the skull that results in altered mental state. tbi occurs more than any other disease, including breast cancer, aids, parkinson’s disease and multiple sclerosis, and affects all age groups and both genders. in the us and europe, the magnitude of this epidemic has drawn national attention owing to the publicity received by injured athletes and military personnel. this increased public awareness has uncovered a number of unanswered questions concerning tbi, and we are increasingly aware of the lack of treatment options for a crisis that affects millions. although each case of tbi is unique and affected individuals display different degrees of injury, different regional patterns of injury and different recovery profiles, this review and accompanying poster aim to illustrate some of the common underlying neurochemical and metabolic responses to tbi. recognition of these recurrent features could allow elucidation of potential therapeutic targets for early intervention. d is ea se m od el s & m ec ha ni sm s d m m dmm.biologists.org traumatic brain injury at a glanceat a glance an electronic version of this poster is available online. d is ea se m od el s & m ec ha ni sm s d m m neurochemical changes associated with tbi normal transmission of signals involves neurotransmitter-mediated activation of receptors and subsequent controlled ionic changes in the postsynaptic membranes of neurotransmitter-releasing cells. ionic changes across the bilipid membrane are meticulously regulated by energy-dependent sodium-potassium (na+-k+) atpase pumps, which maintain the membrane potential between − and − mv (katsura et al., ). tbi induces transient cell membrane disruptions that lead to redistribution of ions and neurotransmitters, altering the membrane potential (see poster, panels b and c). during the acute phase (≤ hour) after tbi, there is a massive release of glutamate from presynaptic terminals, which disrupts ionic equilibrium on postsynaptic membranes. the amount of potassium (k+) released increases with injury severity, as measured by microdialysis (katayama et al., ; kawamata et al., ). in these early studies, mild fp injury produced a . - to . -fold increase in extracellular [k+] levels that was blocked by tetrodotoxin (a neurotoxin that prevents brain cell firing), suggesting that this rise in [k+] is related to neuronal firing. more severe injuries produced greater increases ( . - to . -fold) in [k+] that were tetrodotoxin-resistant. administration of kynurenic acid, an antagonist of excitatory amino acids, attenuated the [k+] increase in a dose-dependent manner, suggesting that the k+ surge is dependent on excitatory neurotransmitters. in order for brain cells to fire again, ionic equilibrium must be re-established, which requires atp (cellular energy). in addition to rising [k+], calcium (ca +) accumulation is also commonly observed after tbi (osteen et al., ). accumulation of intracellular ca + activates mitochondrial ca + uptake. ca + overloading of the mitochondria has been shown to induce oxidative stress and to impair mitochondrial function (xiong et al., ; peng and jou, ). to determine the effects in the context of tbi, accumulation of isotope-labeled ca + ( ca +) was measured in adult rats after fp injury. increases in ca + were seen as early as  hours after the initial injury, and a return to control levels has been observed between days (fineman et al., ) and days (deshpande et al., ) post-injury. ca + accumulation corresponded with the presence of cognitive deficits, which were detected using the spatial memory task, the morris water maze. the surge in ca + and the cognitive problems both recovered by days post-injury (deshpande et al., ; sun et al., ). whereas the influence of animal age on glutamate and k+ changes have not been determined after injury, age effects on the pattern of acute ca + accumulation have been observed, with younger animals showing faster normalization after injury and delayed secondary increases associated with cell death compared with older animals (osteen et al., ). in summary, tbi gives rise to early ionic and neurotransmitter perturbations that initiate a cascade of events that disrupt normal cellular function, including changes in glucose metabolism, free radical production and mitochondrial dysfunction. changes in cerebral glucose metabolism in tbi glucose is the primary fuel source of the adult brain and its processing through the glycolytic pathway provides carbons for the tricarboxylic acid (tca) cycle for energy production in the form of atp. changes in cerebral glucose metabolism (cmrglc) have been established as a hallmark response after tbi. two chemical isotopes ( f-dg and c- dg) are frequently used to measure glucose uptake (transport) into the brain. glucose analogs are metabolized by the enzyme hexokinase, which is the first enzyme in the glycolytic pathway (see poster, panel d). once these isotopes are cleaved by hexokinase they become trapped in the cells, which allows the accumulation of glucose to be measured. autoradiographic images are generated to look at regional changes in isotope-glucose uptake, which can be quantified according to the density of the gray scale. darker regions reflect greater glucose uptake and whiter regions reflect lower glucose uptake (see poster, panel e). these isotopes have been used to show a rapid increase in glucose uptake followed by a prolonged period of glucose metabolic depression, as observed in both experimental and clinical head injury (yoshino et al., ). following fp injury in adult rats, the early transient increase in cmrglc can be detected minutes post-injury and it has been shown that this can be attenuated by administration of kynurenic acid (kawamata et al., ). it has been proposed that this initial increase in cmrglc is due to an increased requirement of cellular energy to restore the ionic balance and neuronal membrane potential (hovda et al., ; hovda et al., ; hovda et al., ). this acute period of ‘hyperglycolysis’ has been observed within the first days after severe human head injury (bergsneider et al., ). the acute period of increased cmrglc is followed by a prolonged period of decreased cmrglc. this decrease in cmrglc has been observed in experimental models of fp and cci (andersen and marmarou, ; yoshino et al., ; kawamata et al., ; richards et al., ; chen et al., ), and has also been documented in human tbi (bergsneider et al., ; o’connell et al., ). in the experimental models, the magnitude and duration of this glucose metabolic depression were found to increase with injury severity. glucose metabolic depression was maintained for , or days after mild, moderate or severe fp injury in adult rats, respectively (mild and moderate are shown in panel e of the poster) (hovda et al., ). cci injury has been found to induce a more profound and longer-lasting depression in the penumbra (area adjacent to the core of cells that will die) than does fp injury (sutton et al., ; prins and hovda, ). consistent with the experimental model data, global cortical cmrglc depression was found to be disease models & mechanisms traumatic brain injury at a glance at a glance table . models of tbi tbi model effects induced in mild tbi model effects induced in severe tbi model fluid percussion (fp) general brain movement, a low level of cell death, transient behavioral impairments general brain movement, cell loss, long-lasting behavioral deficits controlled cortical impact (cci) focal lesion, behavioral deficits larger focal lesion, more severe and long-lasting behavioral impairments weight drop general brain movement, a low level of cell death, transient behavioral impairments general brain movement, cell loss, brain stem injury, long- lasting behavioral deficits d is ea se m od el s & m ec ha ni sm s d m m greater in severely injured tbi patients, although this was not closely associated with levels of consciousness (bergsneider et al., ). however, glucose metabolic rates in the thalamus, brain stem and cerebellum significantly correlated positively with the levels of consciousness, as measured by the gcs (hattori et al., ). age-related differences in the magnitude and duration of cmrglc depression have been demonstrated in experimental models of tbi (see poster, panel f). specifically, the duration of glucose metabolic depression increases with age. fp-injured postnatal day (pnd) juvenile rats show glucose metabolic recovery to the level of age- matched control animal (sham) levels within days (thomas et al., ), whereas recovery takes approximately days in adult rats. in the diffuse injury model, adult-like patterns in glucose metabolism depression are achieved during adolescence (prins and hovda, ). following cci in the adolescent rat (pnd ), the metabolic rates in subcortical and cortical structures recover within or days, respectively (prins and hovda, ). a longer-lasting glucose metabolic depression was observed in the cortex among pnd (adult) rats with cci injury, as shown in the poster (panel f). in general, the younger animals seem to show faster reversion of glucose metabolic depression. in humans, there has only been one study that examined glucose uptake after tbi in the pediatric brain ( months to years of age), but young and adolescent children were not compared with each other or with adults (worley et al., ). comparison of glucose metabolic changes in tbi between different age groups within the pediatric population, or a comparison between adults and children, has not yet been made in humans. regardless of age, the prolonged glucose metabolic depression reflects a period of time during which glucose uptake into the brain is compromised. this could cause downstream negative effects if the energy demands of the brain are not sufficiently met. post-tbi energy crisis: causes and consequences although decreased glucose uptake after injury seems to be a universal response, the underlying mechanism remains unknown. there are three possibilities: decreased blood availability [which depends on cerebral blood flow (cbf)], defects in glucose transporter function or decreased metabolic demand for glucose. the rapid increase in cmrglc immediately after injury reflects an acute period of increased glucose consumption (as outlined above) and this occurs during a time when cbf has been shown to decline (golding et al., ). in an earlier study, the adult rat brain showed a % decrease in cortical cbf within minutes of fb injury, and the level remained significantly low for   hours, with recovery occurring at hours post-injury (yamakami and mcintosh, ). two hours after weight-drop injury, grundl et al. observed decreases in cbf in both immature and mature animals (grundl et al., ). during this acute phase, when cbf does not meet the cerebral metabolic needs of the tissue, this mismatch or ‘uncoupling’ can initiate cascades of secondary injury events and energy crisis. so, do these cbf changes limit glucose availability? plasma glucose levels in head injury patients are difficult to determine, because the levels are carefully maintained within specific ranges (vespa et al., ). experimental studies in both immature and mature rats did not reveal significant changes in plasma glucose supply after tbi and did not suggest substrate limitation (prins and hovda, ). another reason for decreased glucose uptake after tbi could be related to impaired glucose transport through the blood vessels and into brain cells. adult rat studies have shown decreased neuronal glucose transporter (glut ) immunoreactivity - hours after fp injury (balabanov et al., ); however, the expression of this neuronal glucose transporter is patchy in clinical cases of tbi, i.e. regions with increased and decreased expression are present (cornford et al., ). hattori et al. examined the f-dg kinetic changes following moderate to severe tbi in humans and determined that hexokinase activity was globally decreased, with glucose transport impairments occurring specifically within the contusion sites (hattori et al., ). collectively, the studies indicate that glucose transport across the blood-brain barrier is substantially affected by tbi in both animal and human brains. finally, decreases in cerebral glucose levels could reflect problems with glucose metabolism within the cell. there is increasing evidence that the glycolytic processing of glucose is affected by trauma. following cci injury, glucose metabolic processing was determined with [ , c]-labeled glucose infusion (bartnik et al., ). proton nuclear magnetic resonance (nmr) spectroscopy revealed a - % increase in the level of glucose that is shunted towards synthesis of pentoses (used in the synthesis of nucleic acids) via the pentose phosphate pathway at . hours and hours post- injury (see poster, panel d). furthermore, nicotinamide dinucleotide (nad+) concentrations have been shown to decrease after injury (vagnozzi et al., ; satchell et al., ), which could be at least partly attributable to increased consumption by a dna repair enzyme, as described in the subsequent section. nad+ is a necessary cofactor for the glycolytic enzyme gapdh (glyceraldehyde -phosphate dehydrogenase), so reductions in nad+ levels can cause glycolytic inhibition (sheline et al., ). pyruvate dehydrogenase (pdh) is the enzyme that connects the glycolytic pathway to the mitochondrial tca cycle. phosphorylation of the e subunit of pdh, which inhibits pdh function and therefore carbon entry into the mitochondria, has been shown to occur at a higher frequency than normal at hours after cci injury (xing et al., ). these tbi-induced alterations in glycolytic enzyme functioning ultimately decrease the ability of glucose to be efficiently processed for oxidative metabolism, and thereby contribute to the post-tbi energy crisis, reflected by reductions in atp production (see poster, panel d). the role of free radicals in tbi increased generation of free radicals is another factor that contributes to the tbi-induced metabolic crisis. free radicals are molecules with unpaired electrons. these compounds are highly reactive because they attempt to gain electrons from surrounding substances, which can result in cell membrane, protein and dna damage (see poster, panel d). there are two main families of free radicals: reactive oxygen species (ros) and reactive nitrogen species (rns). production of o – is a consequence of normal metabolism, and this species is a precursor to hydrogen peroxide (h o ), which can generate hydroxyl radicals (•oh) via the fenton reaction. the •oh is one of the most reactive chemical species. reaction of o – with nitric oxide (no•) produces peroxynitrite (onoo–). normal metabolic activities produce levels of ros that are well managed by cellular antioxidant defense systems. it is only after cerebral injury that the levels of ros production overwhelm dmm.biologists.org traumatic brain injury at a glanceat a glance d is ea se m od el s & m ec ha ni sm s d m m scavenging systems and result in oxidative damage (o’connell and littleton-kearney, ; kerr et al., ; hall and braughler, ). mitochondria are a source of free radical generation. during normal metabolism, the tca cycle generates reducing equivalents to produce atp. electrons are normally transferred along the electron transport chain, with only - % of the oxygen generating oxygen radicals at complex i in the respiratory chain. however, following tbi, changes in the availability of these reducing equivalents is diminished and the production of o – is increased. concomitantly, tbi-induced intracellular ca + accumulation can activate numerous enzymes, including xanthine dehydrogenase, phospholipase a and nitric oxide synthase (nos), which increase o – and no• production (lewén et al., ). despite the short-lived nature of free radicals, their production has been quantified after brain injury. in severely injured mice, hydroxyl radical (•oh) production increases % within the first minute, peaks at  minutes after injury and subsequently decreases (hall et al., a; hall et al., b). in contrast with this transient period of •oh formation, severe cci-injured rats showed a % increase in •oh production, which was sustained above baseline for minutes (marklund et al., ). a similar pattern in •oh production has been observed after impact injury in the adult rat (sen et al., ; sen et al., ). acute increases in nos have also been reported after fp and cci injury. fp injury induces nos expression between and hours in immature vascular smooth muscles and neutrophils (clark et al., ). in adult rats, cortical nos levels increased between and days, as determined by immunostaining astrocytes and macrophages (wada et al., ). in contrast, cci injury produced a more rapid increase in nitrate levels, with a peak at minutes and a return to baseline by hours post-injury (rao et al., ). in addition to direct measurement of radical formation after tbi, indirect evidence can also be quantified via lipid peroxidation, protein nitration and dna oxidation. lipid peroxidation occurs when ros react with polyunsaturated fatty acids, causing conformational changes and membrane permeability (hall et al., b). increases in markers of lipid peroxidation have been observed - hours after weight-drop (hsiang et al., ; marmarou et al., ; vagnozzi et al., ; lewén and hillered, ; tyurin et al., ) and cci (singh et al., ) injury. within the first minute following tbi, lipid peroxidation was shown to increase from an undetectable level to . nmol/g, and peaked at hours post-tbi ( . nmol/g), progressively decreasing thereafter (lewén and hillered, ). protein oxidation or nitration products were significantly elevated minutes after cci injury in adult mice and returned to baseline by hours (singh et al., ). interestingly, the magnitude and duration of protein oxidative damage was inversely related to injury severity following weight- drop injury in the adult rat (petronilho et al., ). mild tbi produced a threefold increase in protein carbonyls in the cerebellum, cortex hippocampus and striatum immediately after injury, peaking at hours and remaining elevated at hours. severe tbi, by contrast, caused decreased levels of protein carbonyls at all time points. it has also been demonstrated that free radical damage to dna can occur owing to the activation of dna repair enzymes that generate lesions. poly-adp ribose polymerase (parp) is a nuclear dna repair enzyme that consumes nad+ in the presence of single and double dna strand breaks, and its activity has been shown to increase after various types of brain injury. pathological activation of parp has been shown to decrease cytosolic nad+ pools, to inhibit glycolytic processing of glucose and to decrease atp production (cipriani et al., ; alano et al., ). evidence of parp hyperactivation in ischemia and the demonstrated neuroprotective potential of parp inhibitors encouraged research into the role of parp in tbi. satchell et al. reported elevation in parp (a subtype of parp enzymes) activity hours after cci injury (satchell et al., ). this activity level remained significantly greater than that in controls for days post-injury. inhibition of parp activity decreased the lesion size at hours after fp injury, but did not decrease the number of apoptotic cells (laplaca et al., ). partial parp inhibition after cci injury preserved cellular nad+ concentrations and improved functional performance in the morris water maze (satchell et al., ). although age-dependent effects on free radical production or consequent damage in tbi have not been studied in depth, age- related differences in antioxidant defense systems have been examined. after cci injury, glutathione peroxidase (gpx) activity was examined in immature ( -day-old) and adult mice (fan et al., ). gpx activity increased at hours in the adult, but no change was observed in the immature brain. this lack of increase in antioxidant response in the younger brain might indicate an increased vulnerability to oxidative damage after injury. confirmation of this in human tbi patients is currently lacking. the central role of mitochondria in tbi mitochondria play a crucial role in the pathophysiology and energy crisis associated with brain injury. accumulation of both ca + and ros after injury, as discussed above, contributes to mitochondrial impairments. excessive ca + influx can overwhelm mitochondrial ca +-buffering capacity and the rate of efflux by the mitochondrial na+-ca + exchanger. the resulting ca + accumulation has been shown to contribute to mitochondrial membrane-potential collapse (vergun et al., ). it is clear that ca + and oxidative stress act in concert to impair mitochondrial function; however, it is not clear which comes first. one hypothesis is that excessive glutamate stimulation activates nadph oxidase, thereby generating oxidative stress, which in turn activates parp , causing depletion of nad+ stores and ultimately resulting in cell death through inactivation of metabolism (brennan et al., ). an alternative mechanism has been proposed, in which mitochondrial ca + accumulation causes membrane-potential compromise, which generates excessive free radicals, leading to activated parp , depleted nad+ concentrations and, ultimately, cell death (duan et al., ; abramov and duchen, ). although the exact order of events remains controversial, the end result is impaired mitochondrial function, reduced energy production and potential for cell death, which have all been observed following tbi in experimental models. decreases in coupling of the electron transport chain and oxidative phosphorylation have been shown at minutes after injury, with recovery at hour post-cci in the adult mouse brain (singh et al., ). more prolonged decreases in respiratory control ratio and ca +-buffering capacity were also seen between and  hours. cci injuries also resulted in an immediate decrease in atp concentrations, decreased mitochondrial membrane potential, increased mitochondrial permeability transition and disease models & mechanisms traumatic brain injury at a glance at a glance d is ea se m od el s & m ec ha ni sm s d m m increased ros production in isolated cortical synaptosomes (sullivan et al., ; sullivan et al., ). long-lasting changes in mitochondrial respiration have also been reported following cci injury (xiong et al., ). tbi induced a significant reduction in oxidative phosphorylation at hour post-injury; this decrease persisted for days. in the ipsilateral cortex, greater mitochondrial ca + accumulation and lower atp production were observed. recurring mitochondrial impairments result in activation of both apoptotic and necrotic pathways, contributing to cell death (lewén et al., ; robertson, ). alterations ca + in mitochondrial energy metabolism have also been described in the immature rat. tbi resulted in uncoupling of respiration within hour after injury and significant decreases in mitochondrial respiration by  hours after injury (robertson et al., ). several age-associated differences in expression of proteins involved in mitochondrial energy metabolism and cell death pathways exist. for example, the electron transport chain proteins ii, iii and iv reach adult expression levels within the first few months of life, whereas the proteins i and v reach adult expression levels within weeks of birth (bates et al., ). respiration- dependent ca + uptake is also influenced by age. in mitochondria isolated from immature animals, under normal respiratory conditions, respiration-dependent ca + uptake is decreased; however, the opposite occurs under injured conditions (sharma et al., ; robertson, ). mitochondria from immature rats also show increased susceptibility to apoptosis; this increased susceptibility might be due to increased expression of pro-apoptotic proteins (soane et al., ). these combined differences in protein expression could contribute to increased vulnerability of the younger brain after injury. depending on the time after injury, these changes in mitochondrial function are potentially reversible if the post-tbi cellular energy crisis can be treated. therapeutic opportunities for tbi the physiological responses of the brain to tbi are complex and interdependent. cascades of various neurochemical and metabolic processes affect one another, and, as our understanding grows, so too does our appreciation of this complexity. collectively, the observed impairments at numerous points in the glycolytic pathway and oxidative metabolism of glucose have prompted researchers to consider what would be the optimal cerebral substrate after head injury (see poster, panel g). growing evidence has documented the brain’s ability to increase its reliance on alternative substrates under conditions of energy stress [starvation (dahlquist and persson, ; hawkins, ; hawkins et al., ; kreis and ross, ), hyperketonemia (owen et al., ; sokoloff ), ischemia (vannucci and vannucci, ), diabetes (wahren et al., )]. indeed, a surge of articles reporting the neuroprotective effects of monocarboxylates (lactate, pyruvate and ketones) has emerged in the last decade. for example, uptake of radioactively labeled lactate within the injury site at minutes after fp injury has been observed, suggesting cellular use of the substrate (chen et al., ). direct administration of lactate was later shown to improve morris water maze performance (rice et al., ; holloway et al., ); however, it did not reverse tbi-induced decreases in atp (prieto et al., ). administration of three injections of sodium pyruvate spaced -hour apart following cci injury have been shown to attenuate cortical cell loss as measured at hours and weeks post- injury (fukushima et al., ), and this treatment also improves neurobehavioral recovery (moro and sutton, ; moro et al., ). in addition to these monocarboxylates, ketones have also been shown to confer neuroprotection when provided as an alternative fuel source after tbi. administering the ketogenic diet after cci injury reduced cortical contusion volumes, improved motor and cognitive function, and alleviated cellular atp reductions in the adolescent rat brain (prins et al., ; prins, ; prins et al., ; appelberg et al., ; deng-bryant et al., ). ketosis has also been shown to decrease cytochrome c release and levels of markers of apoptotic cell death after cci injury in the juvenile rat (hu et al., a; hu et al., b). the fasting of adult animals has also been used to induce ketosis, which has been shown to decrease oxidative stress and ca + loading, and to improve mitochondrial oxidative phosphorylation at hours post-cci injury (davis et al., ). addition of ethanol pyruvate to cerebrocortical slices exposed to oxidative stress alleviated atp decreases and improved cell survival (zeng et al., ). pyruvate also improved atp depression, alleviated gapdh inhibition and prevented cell loss in hippocampal excitotoxicity (izumi and zorumski, ). additionally, pyruvate has been shown to have antioxidant properties in m muller cells (frenzel et al., ) and human neuroblastoma cells (jagtap et al., ). treatment with acetyl-l-carnitine after injury improved behavioral outcomes and decreased lesion volume (scafidi et al., ). despite the emergence of neuroprotective evidence for alternative substrates, it is important to keep in mind that the multiple foci of physiological disruptions that are generated by tbi require a multi-targeted approach. the monocarboxylates have been demonstrated to improve cellular energetics, decrease production of free radicals and reduce cell death, and the metabolism of these downstream alternative substrates could provide a critical therapeutic approach to tbi (pan et al., ; prieto et al., ; veech et al., ; veech, ). unfortunately, there have been no clinical trials or application of alternative substrate therapy in tbi. future studies must address the effectiveness of any therapeutic intervention in various age groups given the known pathophysiological differences in response to tbi. conclusions tbi is a complex dynamic process that initiates a multitude of cascades of pathological cellular pathways. its symptomatic presentation varies with each individual, injury type, injury severity, age and gender, making it challenging to diagnose, understand and treat. research efforts to understand the common underlying neurochemical and metabolic responses to tbi could provide further therapeutic options for early intervention of tbi in patients of all ages. competing interests the authors declare that they do not have any competing or financial interests. funding this work was funded by the ucla brain injury research center, nih ns . supplementary material supplementary material for this article is available at http://dmm.biologists.org/lookup/suppl/doi: . /dmm. /-/dc references abramov, a. y. and duchen, m. r. 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( ). exogenous ethyl pyruvate versus pyruvate during metabolic recovery after oxidative stress in neonatal rat cerebrocortical slices. anesthesiology , - . disease models & mechanisms traumatic brain injury at a glance at a glance d is ea se m od el s & m ec ha ni sm s d m m 	introduction 	an electronic 	neurochemical changes associated with tbi 	changes in cerebral glucose metabolism in tbi 	post-tbi energy crisis: causes and consequences 	the role of free radicals in tbi 	the central role of mitochondria in tbi 	therapeutic opportunities for tbi 	conclusions doi: . /j.enpol. . . energy policy ( ) – article in press *correspondi e-mail addre jgkoomey@lbl.g - /$ - see doi: . /j.enp using energy scenarios to explore alternative energy pathways in california rebecca ghanadan a, *, jonathan g. koomey b a the energy and resources group (erg), barrows hall, university of california, berkeley, ca - , usa b end-use forecasting group, lawrence berkeley national laboratory and stanford university, cyclotron road, ms - , berkeley, ca , usa abstract this paper develops and analyzes four energy scenarios for california that are both exploratory and quantitative. the business- as-usual scenario represents a pathway guided by outcomes and expectations emerging from california’s energy crisis. three alternative scenarios represent contexts where clean energy plays a greater role in california’s energy system: split public is driven by local and individual activities; golden state gives importance to integrated state planning; patriotic energy represents a national drive to increase energy independence. future energy consumption, composition of electricity generation, energy diversity, and greenhouse gas emissions are analyzed for each scenario through . energy savings, renewable energy, and transportation activities are identified as promising opportunities for achieving alternative energy pathways in california. a combined approach that brings together individual and community activities with state and national policies leads to the largest energy savings, increases in energy diversity, and reductions in greenhouse gas emissions. critical challenges in california’s energy pathway over the next decades identified by the scenario analysis include dominance of the transportation sector, dependence on fossil fuels, emissions of greenhouse gases, accounting for electricity imports, and diversity of the electricity sector. the paper concludes with a set of policy lessons revealed from the california energy scenarios. r elsevier ltd. all rights reserved. keywords: energy scenarios; california; energy forecasting no amount of sophistication is going to allay the fact that all your knowledge is about the past and all your decisions are about the future (wilson, ). it is far better to foresee even without certainty than not to foresee at all (poincare, ). . introduction in early , electricity blackouts and high-energy prices in california brought energy issues to the forefront of public attention. while the visibility of the crisis highlighted numerous immediate inadequacies in the state’s energy system, it also revealed deeper needs for innovative and systematic approaches to energy analysis—both within california and in other domestic and international contexts. the crisis illuminated the relevance of alternatives to business-as-usual (bau) ng author. tel.: + - ; fax: + - . sses: rebeccag@socrates.berkeley.edu (r. ghanadan), ov (j.g. koomey). front matter r elsevier ltd. all rights reserved. ol. . . trends and possibilities for expected and unexpected change. consideration of alternative energy pathways is critically important to california’s uncertain and chan- ging energy context. alternative pathways are increas- ingly important if california is to adequately balance its energy needs with other economic, social, environmen- tal, and land use interests, especially with a growing population and economy. successful long-term energy policy and planning requires systematic information that connects current choices and uncertainties with their potential implica- tions for the future. in california, a substantial body of information exists on specific dimensions of its energy system, such as market analyses, energy and price forecasts, and energy efficiency studies. in addition, an abundance of articles and reports have sought to analyze and interpret the implications of california’s electricity crisis. in many cases, however, the available energy literature offers highly specific information a detailed summary of california energy references is provided in appendix b. article in press r. ghanadan, j.g. koomey / energy policy ( ) – oriented to expert audiences or provides news-based information that gives little insight into the deeper driving forces or broader consequences of existing conditions. available information is often poorly equipped to explore processes of change, aggregate outcomes, and unexpected results. thus, the challenge is to develop techniques and information sharing that can connect available information, immediate concerns, and desired outcomes for effective decision-making. this article presents energy scenarios as a useful method for exploring energy choices in california from a long-term and systematic perspective. considerable discussion and analyses have focused on global and us energy scenarios, however this study is unique in developing and analyzing energy scenarios for califor- nia. the significance of california’s energy choices both inside and outside of the state makes this study relevant to a broader domestic and international audience. within the us, california is the most populous and economically productive state and has been a leader in national energy policy. california is also the fifth largest economy in the world, ranks tenth in terms of primary energy consumption, and approximately fifteenth in terms of greenhouse gas emissions. with a history of being on the vanguard of energy policy and with one of the most scrutinized set of electricity sector reform policies enacted in the world, california’s energy choices and outcomes promise to continue to influence the direction of deregulation and energy policy in us and other countries. this paper develops and evaluates four california energy scenarios that explore a range of possible future energy pathways. the bau and three alternative energy scenarios developed in this paper combine narrative and modeling methods to illustrate alternative contexts and analyze potential outcomes. the bau scenario repre- sents a pathway guided by outcomes and expectations following the energy crisis. three alternative scenarios represent contexts where clean energy plays a greater role in california’s energy system: split public is driven by local and individual activities; golden state gives importance to integrated state planning; patriotic energy represents a national drive to increase energy independence. the first section of this paper introduces the energy scenario approach and situates this method within the context of energy analysis. it contrasts energy forecasts and scenarios and provides a foundation for using scenarios to explore a range of possible energy pathways for california. the second section uses a distinct methodology to develop the bau and three alternative for example see interlaboratory working group ( ), nep ( ), reddy et al. ( ), and world energy council ( ). greenhouse gas emissions estimate is based on the following data sources: cec ( f), eia ( f,h), and laedc ( ). scenarios around critical uncertainties in california’s energy system. in the third section, the implications of the scenarios are examined using energy modeling techniques to quantitatively evaluate future energy consumption, composition of electricity generation, energy diversity, and greenhouse gas emissions asso- ciated with each scenario through . the paper concludes by presenting a set of critical issues and policy implications illuminated by the analysis. there are many opinions about the plausibility of different energy scenarios in technical, economic, and political terms. this article does not claim that the scenarios presented here are the most likely or most desirable, as predicting the future with accuracy is not really possible (craig et al., ). instead, this article should be read as an exploratory exercise aimed at developing a set of scenario analysis tools and initiating a discussion on alternative future energy pathways. the details of this analysis are important, and there is likely to be a range of opinion on the plausibility of different elements comprising each scenario. however, the broad- er intention of exploring current opportunities and challenges should not be lost to differing opinions on the details. it is our aim that this paper opens the doorway for greater discussion, debate, and comparison from many perspectives on alternative energy pathways in california. . the scenario approach this paper integrates aspects of strategic planning and energy analysis to develop scenarios that are exploratory and analytical. the development of scenario methods as a strategic management and organizational learning tool were pioneered by the business community in the s. strategic management studies of scenarios have de- scribed how the process of developing well-researched and plausible stories about the future can facilitate organizational learning and generate critical insights into strategic decision-making. many of the notable figures in this area come from a core group of ex-royal dutch/shell scenario planners who have played a prominent role in articulating scenario techniques to a wider audience. in energy research, scenarios are most commonly used to characterize an envelope of expected future condi- tions or quantify savings potentials from policy, technology, or behavioral changes. scenarios have gained prominence within the fields of climate change and energy efficiency. notably, the climate change emissions scenarios of the intergovernmental panel on climate change (ipcc) play an influential role in both a well-known example is schwartz’ book, the art of the long view; one of the most popular books on the topic of strategic scenarios ( ). article in press r. ghanadan, j.g. koomey / energy policy ( ) – climate change science and policy (nakicenovic and swart, ). the report, scenarios for a clean energy future, prepared by an interlaboratory working group of us national labs, also represents a substantive use of scenarios in interdisciplinary energy analysis. it analyzes the effects of three different public-policy scenarios on the growth of energy consumption and carbon dioxide emissions over the next years (interlaboratory working group, ). both of these examples reflect a growing effort by energy researchers to address uncertainty and incorporate broader dimensions of society and technological change into their scope of analysis. in this paper, the term ‘‘energy scenarios’’ refers to a set of illustrative energy pathways that are created using a distinct scenario development methodology and quantitatively analyzed using energy modeling tech- niques. the scenario stories provide a set of alternative contexts for exploring different ways that the future may unfold. energy modeling evaluates the systematic changes and impacts resulting from each scenario on fig. . energy scenarios examine a range of possible outcomes that are grounded within system dynamics of the energy system. combining stories and models, scenarios qualitatively explore diverse contexts and quantitatively evaluate potential outcomes. table contrasting energy forecasts and energy scenarios forecasts—what is likely? approach rational focus on analysis and outcomes objective to develop most likely pathway and characteriz uncertainty methods analytical models and driver variables treatment of uncertainty probabilistic methods, statistics, and transparen assumptions important actors reliance on experts, state and national planning california’s energy system over the next few decades (fig. ). scenarios are distinct from forecasts in that they explore a range of possible outcomes resulting from uncertainty; in contrast, forecasts aim to identify the most likely pathway and estimate uncertainties. as a result, forecasting models are most effective under conditions when information availability is extensive and understanding of governing dynamics is high. however, when systems are less well defined and interrelationships between factors are less stable and predictable, energy forecasts have shown themselves to be poorly equipped to characterize processes of change. a recent review of energy forecasts over the last years in the us showed that historical forecasts have routinely failed to represent actual conditions by systematically overestimating consumption and underestimating un- certainties (craig et al., ). this paper integrates stories and models into a set of scenarios that explore alternative energy pathways for california in a way that highlights a range of possible conditions and maintains consistency with physical dynamics of the state’s energy system. drawing from gallopin and raskin, scenario narratives provide ‘‘texture, richness, and insight’’ while models offer a level of ‘‘structure, discipline, and rigor to the analyses of socioeconomic, resource, and environmental condi- tions’’ (gallopin and raskin, ). scenarios do not try to account for every possible outcome, rather they focus on developing a set of insightful lenses for exploring processes of change (table ). . developing the exploratory scenarios the objective of developing scenario storylines is to create bounded contextual frames for exploring the future energy system from different perspectives. this section reviews the development of four california energy scenarios using a six-step process adapted from scenarios—what could be? focus on process, strategy, and learning e to develop a number of insightful pathways that explore uncertainties qualitative stories evaluated by models cy of exploration of critical uncertainties, and separation of predetermined and uncertain elements in crafting stories agencies group facilitators, strategists, problem-solvers article in press table six-step process for developing scenarios . define a focal issue . list important forces in the environment . evaluate forces by importance and uncertainty . select a scenario logic . develop scenarios around critical uncertainties . evaluate the implications of the scenarios adapted from schwartz ( ). table examples of important factors in california’s energy system future form of power purchase/market structure dominance of economic costs versus other metrics (air quality, energy diversity, etc.) agents of leadership—public, municipalities, state, federal prominence and interpretations of security-energy linkages reliance on electricity imports from other states perception of distributed generation benefits/costs balance between supply and demand focus strength of state energy regulatory authority public view of energy choices as personal responsibility versus paternalistic provision strength of community, consumer, non-government organizations relative growth and composition of the state economy level of interest in energy infrastructure improvements target of technology support—r&d, demonstration projects, market pull/push, institutions motivation for developing hydrogen based technologies and infrastructure facility of interconnection for distributed generation fuel price and supply volatility versus stability electricity cost recuperation of long-term contracts r. ghanadan, j.g. koomey / energy policy ( ) – schwartz ( ) that is outlined in table . this process involves identifying, prioritizing, and negotiating the most interesting, uncertain, and important elements in the state’s energy system. this section develops four different scenarios to explore underlying tensions, opportunities for change, and ways that uncertainties may play out in different ways in california’s energy system. it aims to show the significance of each scenario and elaborate underlying assumptions. this methodology is one of many possible approaches that may be used to generate many potential stories. the four scenarios presented here aim to give insights into potential energy pathways in california. step : defining a focal issue. the first step in developing scenarios identifies a unifying question or idea to define what the scenarios will explore. scenarios provide alternative organizing frames for evaluating and assembling information relevant to the focal issue, where each scenario represents a different perspective on the issue. in our analysis, the focal issue poses a set of questions about clean energy and possible alternative pathways in california: california energy scenarios focal issue—how might cleaner energy pathways develop in california? what will be the drivers of change over the next decades? how could california’s energy system differ from business-as-usual expectations? the focal issue reflects an important set of uncertain- ties in california’s future energy pathway. profound changes in california’s energy pathway, accelerated by deregulation and the state’s energy crisis, challenge the likelihood of bau pathways. these transformations highlight the relevance of exploring alternative energy pathways. step : determining the important factors in the system. armed with a compelling focal issue and system to investigate, the next step elaborates a list of important factors in california’s energy system. the goal of this step is to define the universe of interactions and elements that may be considered in the scenarios. it is useful for determining what information is relevant to the analysis and where there are gaps in understanding. used in a participatory context, this step can be used to bring multiple perspectives to bear on a single focal issue. our analysis created a list of over one hundred important factors shaping california’s energy system. table presents a truncated list of some of the many important factors. step : evaluating forces by importance and uncer- tainty. the highly interconnected nature of social, political, economic, and technical dimensions of the state’s energy system means that the list of important factors created in step two is long and composed of interrelated concepts. step three identifies and then evaluates driving forces underlying factors listed in step two. fig. presents these fourteen driving forces. the figure evaluates each driving force by relative impor- tance and uncertainty in the state’s energy system. the driving forces in the upper right of the figure are the most important and highly uncertain and are labeled as critical uncertainties in california’s energy system. they include: the relevance of energy diversity, relative attention to oil and transportation, long-term promi- nence of energy and security, types of clean energy activities, and role of distributed generation. the critical uncertainties form the basic themes and tensions for the scenario storylines. step : selecting the scenario logic. in developing scenarios, critical uncertainties illuminate and organize the foundational themes for the scenario storylines, with each scenario engaging with the critical uncertainties in different ways to generate alternative energy pathways. step four describes a logical relationship between the four scenarios that is linked to three basic questions about the importance of energy diversity, the role of government involvement, and scale of primary influence in california’s future energy pathway. the scenario logic chain and key branch points are shown in fig. . at the first point of divergence, each of the three alternative scenarios represents a context where energy article in press fig. . scenario branch points in california’s future energy pathway. the logic connecting the alternative energy scenarios to the bau energy pathway is linked to three fundamental questions that form central points of divergence and relation for the energy scenarios. fig. . identifying and evaluating driving forces in california’s energy system by importance and uncertainty. the most important and most highly uncertain driving forces are categorized as critical uncertainties in california’s energy system. the five critical uncertainties highlighted in this figure form the underlying themes of the scenario storylines. r. ghanadan, j.g. koomey / energy policy ( ) – diversity gains prominence compared to bau condi- tions. at the second point of divergence, clean energy activities in split public are led by active segments of the public rather than government policies or activities. in golden state and patriotic energy, government plays prominent roles in leading new clean energy activities. at the third point of divergence, golden state is driven by forces internal to the state’s energy planning context. an era of energy leadership and cooperation emerges from integrated state energy planning. patriotic energy is a scenario driven by external changes to the us energy pathway under an increasingly hostile and insecure international world order. together the scenarios explore a range of different potential driving forces and contexts for change. step : develop stories around critical uncertainties. step five composes storylines for each scenario describ- ing how the future may unfold. each story illuminates different dimensions of the unifying focal issue. to- gether the scenarios reflect many of the driving forces with potential to reshape california’s pathway. none of these stories represents an ideal outcome or realization of the full potential of clean energy. instead the scenarios explore different contexts where new priorities may emerge. these stories aim to inspire discussion about alternative future pathways and expand explora- tion beyond bau forecasts. . base case storyline—bau scenario the bau scenario depicts a world formed by the convergence of historical trends with outcomes and expectations following california’s energy crisis in – . in the bau context of post-deregulation uncertainty, california develops neither an integrated logic nor a unified vision for the future and instead reflects crisis-inspired growth of the electricity sector and continuation of historical trends in the residential, transportation, commercial, and industrial sectors. state government struggles to establish a clear regulatory article in press the california energy commissions emerging renewables buy- down program offers $ /kw or % off the system purchase price of new small-scale renewable energy electricity-generating systems (cec, e). r. ghanadan, j.g. koomey / energy policy ( ) – framework, harmonize intra-agency and intra-branch power struggles, and address concerns beyond immedi- ate issues. without energy in the spotlight, individuals revert to pre-crisis preferences and activities. changes in the residential, transportation, commer- cial, and industrial sectors are shaped by incremental trends rather than totally new activities. steady growth in population, development of the economy, and per capita transportation activity characterize the bau pathway. the state economy grows at a rate slower than in the late s, but steadily enough for consumers to increase the size of their homes, buy new cars, drive more, and use bigger and better appliances. public opinion about energy reflects little personal connection to energy choices and outcomes. consumers express the attitude, ‘‘let’s pick up where we left off before the crisis’’. bigger cars and suvs continue to gain market share, and people generally feel entitled to consume what they can afford. hybrid and electric vehicles slowly gain visibility in the bau scenario, but gains are largely isolated to wealthier urban and suburban areas of the state and remain marginal compared to overall activity. the transportation sector reflects increases in trans- portation activity and population growth without major changes to transportation technologies. competitively priced alternative transportation options remain limited. instead, light-duty trucks and sport utility vehicles continue to gain popularity and become an increasing share of total passenger vehicles. the overall national transportation policy context remains resistant to increases in vehicle fuel economy and alternative transportation technologies. as a result, the national fuel economy standard of gasoline and diesel passenger and freight vehicles does not change and the overall fuel economy of california’s passenger vehicle fleet de- creases. under bau conditions, the private sector completes construction of a large fraction of the natural gas power plants approved during and immediately following the energy crisis. long-term electricity contacts negotiated during the energy crisis define much of the composition of electricity generation over the next years. the relevance of this expectation is evidenced by a recent study showing that an estimated % of the long-term electricity contracts negotiated with the department of water resources during the energy crisis were for natural gas power plants that had not yet been built (bachrach, ). the bau scenario incorporates assumptions of significant new electricity capacity additions using the levels of capacity additions from the california energy commission’s electricity outlook (cec, b, tables i- and ii- - ). limited numbers of state-supported renewables projects main- tain capacity levels similar to historic levels, however electricity diversity decreases overall. . alternative storyline —split public scenario in the split public scenario, a motivated segment of the public contests the bau world around them and begins to organize and initiate clean energy activities on individual and local levels. responding to calls for public leadership, self-labeled ‘‘progressive energy en- thusiasts’’ promote activities in the domains where they exert influence and control—in households, consumer preferences, and communities. split public highlights public interest as a critical agent in california’s future energy pathway. the residential, transportation, and commercial sectors become sites of new activities. hybrid and electric vehicles, solar water heaters, energy efficient lights, solar home systems and municipal renewable energy projects proliferate in up to % of households and communities in california by . municipal energy campaigns and directed renewable energy in- itiatives become important new avenues for interested citizens and organizers to extend public influence. san francisco becomes a leader in municipal, commercial, and residential solar and wind energy generation. in addition, cities become key arenas of organizing climate change mitigation policies, and many california cities reduce carbon dioxide emissions to below levels. despite dynamism in certain areas, the reach of split public is limited by a lack of additional cooperation by state government, national policy, and the private sector. without state government and private sector engagement, industrial energy and larger-scale electri- city generation are outside of local control and remain unchanged from the bau scenario. in addition, without changes to national transportation policy, vehicle fuel economies stagnate and fuel cell technologies remain in the domain of research. split public is a scenario that explores how a set of energy activities motivated by individual and community interest can influence cali- fornia’s energy pathway. the relevance of this scenario is highlighted by actual public-initiated energy activities since the energy crisis. for example, the california’s energy commission’s emerging renewables buy-down program has received a dramatic increase in interest from electricity customers since the energy crisis (cec, e). in addition, in november , residents of san francisco passed city propositions b and h which are expected to provide financing for mw of solar and mw of wind power (california solar center, a, b). the state also recently eliminated a sunset clause on net metering authorization, thereby extending authorization for article in press r. ghanadan, j.g. koomey / energy policy ( ) – systems up to one megawatt indefinitely (california legislative counsel, , assembly bill ). in addi- tion, much of the demand reduction during the electricity crisis is attributed to voluntary energy efficiency measures by individual households. all of these activities point to the importance of public action in california’s future energy pathway. . alternative storyline —golden state scenario golden state is a scenario of coordinated activity on individual, local, and state levels. rallying around california’s historic sense of pride in progressive energy technology and policy, earlier fragmentation and crisis give way to a new era of cooperation in energy and resource planning. the lessons learned from the electricity crisis become significant driving forces for new visions about the future. golden state combines active state energy policy with individual and commu- nity activities. the collapse of a prominent energy company, decreasing shareholder confidence, and concerns over corporate accounting draw attention to the importance of achieving a balance between energy sector reform, individual actions, and state-led policy in california’s energy pathway. golden state is simultaneously an aggressive scenario for diversification of the electricity sector and a moderate scenario for individual and local clean energy activities. golden state incorporates the residential, transporta- tion, and community-led activities of split public. however, these changes are adopted more slowly than in split public through participation and public out- reach to reach levels of % of households by . golden state combines these activities with a progres- sive state energy policy and planning mandate focused on diversification and emissions reductions in its electricity sector. to achieve these objectives, state agencies undergo significant reorganization to consoli- date, integrate, and reassert authority to collect energy information and initiate long-term policy and planning. new natural gas power plant construction decreases to half of the construction levels proposed in the bau scenario. a % renewable portfolio standard (rps) becomes the flagship energy policy to create viable and competitive renewable energy markets. the state meets and maintains the % goal by incorporating significant new renewable-based electricity generation primarily in the form of wind, geothermal, and biomass to serve future demand and to decrease imports. consequently, california leads the nation in achieving renewable energy targets and setting carbon dioxide emissions reductions commitments in electricity generation. while golden state makes a leap forward in terms of participatory planning, without additional national policy support, it is unable to realize more extensive changes in the transportation sector. golden state does not create sufficient market-pull or push to develop hydrogen-based fuel cell transportation technologies. golden state adopts existing alternative transportation technologies like hybrid, electric, and natural gas personal vehicles and public transit vehicles to levels of % by . however, lacking national transportation policy, the fuel economy of gasoline and diesel passenger vehicles and freight vehicles continue to stagnate. increasing activity and population offset many of the gains in fuel economy from alternative transportation activities. golden state explores how an extensive set of renewable energy activities in electricity generation together with individual and community activities might affect the future of california’s energy system. the new california rps is an indication of greater state interest in diversification of the electricity sector. passed into law in september , the california rps is one of the strongest state rps policies in the country (california legislative counsel, , senate bill ). it mandates that the fraction of renewable energy-based electricity sold by utilities and private retailers in the state increase % per year to a % renewable market share by . the policy promises to be the catalyst of dramatic new changes in california’s electricity sector and suggests greater state-level intentions to support renewable energy in the future. golden state is an insightful scenario for exploring a pathway of diversified electricity generation. . alternative storyline —patriotic energy independence scenario facing a world of international insecurity, patriotic energy reflects a national drive for greater energy independence. patriotic energy is a world of aggressive energy activities and policies, particularly in the transportation sector, as the country seeks to reduce its dependence on imported oil. national policy and patriotism create powerful drivers for an energy independence movement within the us. this national vision creates a complete reframing of issues of energy, resources, and the environment, creating new alliances and reinterpretations of the american way of doing things. in patriotic energy independence, the availability of a continuous flow of cheap oil becomes increasingly threatened. with numerous forces converging to chal- lenge the political and economic conditions in the us, maintenance of good relations with oil producers becomes an increasingly critical foreign policy challenge. in this changing world, decreasing oil dependence becomes a central pillar of national security policy. in article in press while a small set of options are considered in this study, there is a significant opportunity for additional scenario analysis efforts to develop more comprehensive scenarios that would include the results r. ghanadan, j.g. koomey / energy policy ( ) – the near term, the us focuses on the development of domestic energy resources—national coal, oil, and natural gas are exploited with the best available technologies. development of a hydrogen economy becomes a unifying national vision for the future. massive government investment is directed at devel- opment of an oil-independent transportation system. the president calls upon the us public to embrace the new american dream and buy new low-oil consuming cars. existing hybrid and electric vehicle technologies become critical features of the near-term strategy for reducing transportation oil consumption. national energy policy mandates increases in fuel economy standards for passenger and freight trucks. critical to mid-term strategy, the us provides substantial support for research, development, and commercialization of direct hydrogen fuel cell vehicles. the first fuel cell vehicles are available for commercial sale in the middle of the analysis period; by they comprise % of passenger vehicles on the road. renewable energy becomes a strategic resource for generating electricity, for producing hydrogen gas, and for freeing up domestic natural gas for high value uses. patriotic energy reduces new natural gas power plant construction to % of the bau scenario, filling additional capacity needs with renewable energy-based generation. a national rps is implemented that mandates % renewable energy-based electricity mar- ket share by . california becomes ideally positioned to lead us states in the production of renewable energy- based electricity using wind, geothermal, and biomass and to a lesser extent solar and small-hydro. patriotic energy independence reflects conditions which radically reframe individual activities. it incorpo- rates the residential and commercial sector activities of split public; however in this case, they are motivated by a sense of civic responsibility. solar home systems become symbols of household patriotism. smart cars, hybrids, electric, and later fuel cell vehicles dominate the roads. diversification beyond fossil fuels becomes a driving force and strategic priority across individual, community, state, and national scales. the relevance of the patriotic energy scenario is reinforced by the current foreign policy context that has increased the visibility of energy and security concerns, making oil dependence and energy diversity active topics of state and national energy policy discussion (kerry, ; mcnulty, ). of studies that have appeared since the california crisis reached its peak. for example, a report sponsored by the energy foundation and the hewlett foundation that appeared in late (after the main scenario analysis for this study was completed) contains many examples of cost effective efficiency technologies, including savings potential and cost estimates for options in the residential, commercial and industrial sectors that could be incorporated into a more comprehensive scenario exercise (rufo and coito, ). the sources used to develop the california energy database are referenced in appendix b. . basis for scenario modeling the scenario modeling exercise draws on the context of the scenario narratives, identifies a set of plausible policies and choices for each scenario, and examines the implications of each scenario for future energy con- sumption, composition of electricity generation, energy diversity, and greenhouse gas emissions through . the bau scenario serves as a reference scenario and point of comparison for the alternative scenarios and is based on assumptions reported in state planning literature. the alternative scenarios are based around sets of plausible policies, choices, and patterns that are coherent with the context of each scenario narrative. the scenario elements are modeled using explicit assumptions of how energy, technology, and activity parameters change over time. this approach links contextual narratives to specific physical changes in use patterns, technology attributes, and demographic drivers. economic factors (e.g. costs of alternative technologies, fuel prices, etc.) are incorporated indirectly through the choice of market penetrations for different technologies. the long time horizon of the scenarios is assumed to be sufficient for technologies that are not now cost competitive to become competitive through technological change, research and development, mar- ket pull programs, and other public policies. a detailed treatment of background assumptions and justification for the scenario elements is summarized in appendix a. we do not estimate the costs of the alternative scenarios, a complex task that we leave for future work. table presents modeled elements of the bau scenario. table reviews the modeled elements of the alternative scenarios. it is important to recognize that the scenarios are not intended to incorporate every activity that might be possible under each scenario. rather, the scenario analysis associates a small, specific set of activities to each scenario that are consistent with the narratives and provide an opportunity to explore critical uncertainties in california’s future energy path- way. . the analytical framework the scenario modeling is founded on a detailed sectoral database of historic and forecast data for california and integrated with the scenario-based modeling platform, long range energy alternative article in press table overview of business-as-usual scenario elements business-as-usual logic post-deregulation world characterized by crisis-inspired growth of electricity sector, continuous trends in other sectors, and existing technologies and policies residential increasing population and households, . %/yr a steady economic growth, raising personal incomes household computers and printer use reaches levels of tvs and vcrs, by refrigerator sizes increase, . %/yr greater use of household air conditioning, % by natural gas efficiencies improve for space and water heating technologies, . %/yr transportation increasing population, . %/yr vehicles driven with same number of passengers per vehicle (ex. . people/car) people drive more miles per year, . %/yr increasing popularity of light duty trucks/suvs relative to cars, reaching % by modest penetration of hybrid and electric cars and light duty trucks, % by modest penetration of hybrid, electric, and natural gas buses, % by constant passenger vehicle average fuel economy for gas and diesel vehicles air travel per person increases, . %/yr energy intensity of air travel decreases, � . %/yr freight activity per person increases, . %/yr constant composition of freight activity, % rail, road, water constant freight vehicle fuel economies commercial increasing commercial floorspace, . %/yr constant relative composition of building types saturations of commercial end uses remain the same electricity intensities increase overall, . %/yr natural gas intensities decrease overall, . %/yr industrial increasing industrial value of shipments, . %/yr industrial sub-sector shares of total industrial value of shipments change slightly electricity and natural gas intensities decrease overall, variable % electricity generation natural gas is significant fraction of capacity additions, % of additions – b renewables are moderate fraction of capacity additions, % of additions – c imports make up capacity shortfalls above natural gas and renewables additions minimum import level set to current level of fixed-coal generation imports ( twh) d,e a all annual percentages refer to an average annual rate of change over the scenario horizon of – . b bau scenario uses cec’s ‘‘most likely’’ and ‘‘baseline’’ scenario categories to derive capacity additions (cec, b, table i- and ii- - ). c renewables is used here to refer to renewable energy based electricity generation and does not include large hydroelectric generation. in these analyses, this category includes primarily wind, geothermal, and biomass, and to a lesser extent landfill gas, digestor gas, municipal solid waste, small hydro, and solar. d minimum import level for the bau is equal to the average level of imports from utility-owned, out-of-state coal generation with exclusive sales to california between and (cec, a). e all other bau elements are based on assumptions and expectations derived directly or through interpretation of state data and reports that are summarized in appendix b (table ). r. ghanadan, j.g. koomey / energy policy ( ) – planning system (leap), to create multi-sector end- use model of energy supply and demand in california. the california leap end-use model is used to characterize the composition and structure of energy, fuel use, and greenhouse gas emissions for each scenario between and . the structure and composition leap, is an accounting and scenario-based energy-modeling platform developed by stockholm environmental institute boston center for energy, environment, and emissions applications. http:// www.seib.org/leap. of the base year, , is founded on existing state-level information and is consistent with overall fuel balance and technology and end-use estimates of the magnitude and composition of energy and fuel consumption. the base year ensures a common starting point for the scenarios and grounds the analysis in the reality of the state’s existing energy system. the california energy scenario model considers five demand sectors: transportation, commercial, industrial, and other, and one fuel transformation sector: electricity generation. primary fuels are used directly by demand http://www.seib.org/leap http://www.seib.org/leap article in press table overview of alternative scenario elements a split public golden state patriotic energy logic consumers and communities champion clean energy integrated planning emerges from earlier crisis uncertain international order inspires drive for greater energy independence agents of change household and consumer behavior, local organizing, municipal activities system planning, state energy policy, dialogue and consensus building, priority to state management of resources international security concerns, government-private sector research and development, assertive national policy and planning residential activity level of % of public by activity level of % of public by activity level same as split public, motivated by patriotic interest in decreasing us fossil fuel dependence solar water heaters solar water heaters efficient lighting efficient lighting solar systems, kw solar systems, kw line drying, % line drying, % transport light trucks/suv fraction of passenger vehicles decreases from % to % by light trucks/suv fraction of passenger vehicles decreases from % to % by light trucks/suv fraction of passenger vehicles decreases from % to % by penetration of alternative people- moving vehicles: penetration of alternative people- moving vehicles: complete phase out of full-gas/ diesel passenger vehicles by : hybrid and electric cars and light trucks, average penetrations % of stock by hybrid and electric cars and light trucks average penetrations, % of stock by hybrid and electric, % of stock of passenger vehicles by hybrid, electric, and natural gas bus combined penetrations, % of stock by hybrid, electric, and natural gas bus combined penetrations, % of stock by direct-hydrogen fuel cell, % of stock of passenger vehicles by no change in us passenger and freight vehicle fuel economy standards no change in us passenger and freight vehicle fuel economy standards increased us freight fuel economy standards commercial municipal initiatives lead to mw wind and mw solar by municipal initiatives lead to mw wind and mw solar by activity as split public, motivated by patriotic interest in decreasing us fuel dependence industrial same as bau same as bau same as bau electricity generation natural gas provides % of new capacity additions state renewable portfolio standard of % by national renewable portfolio standard of % by renewable energy sources provides % of new capacity additions, primarily as wind, geothermal, and biomass renewable sources provide % of new capacity additions, primarily as wind, geothermal, and biomass renewable sources provide % of new capacity additions, primarily as wind, geothermal, and biomass imports reduced by > % imports reduced by > % imports reduced by > % a a detailed explanation of key assumptions and justification for the scenario elements is summarized in appendix a (table ). r. ghanadan, j.g. koomey / energy policy ( ) – sectors and to generate electricity. the level of electricity consumption by the demand sectors determines the overall quantity of electricity generated each year. the composition of electricity generation is determined using explicitly assigned technology categories, attributes, merit order, system load curve, and import/export specifications. each individual supply and demand sector is disag- gregated to the level of end uses and technologies which consume, generate, or transform fuels (table ). the model structure is influenced by the type of state-level data that was available for each sector. technologies and/or end uses are characterized by a set of specific parameters, including: market saturation, fuel consumption, energy efficiency, energy intensity, and demographic and/or activity drivers. the modeling framework accommodates policies and changes associated with the scenarios and are directed at specific technologies and end uses. the energy scenarios are modeled by combined changes in activity, structure, and energy intensities over time. article in press table composition of modeling framework: supply sectors, demand sectors, primary fuels sector/fuels categories sub-categories activity parameters residential end-use categories technologies households (# hh) (e.g., air conditioning) (e.g., forced gas heating) saturations (%) unit energy consumption (e/yr) transportation categories technologies population (passenger, air, freight) (e.g., hybrid gasoline-electric cars) passenger miles traveled freight miles traveled end-use categories air miles traveled (e.g., light trucks) share of miles traveled (%) commercial building types end-use categories floorspace (ft ) (e.g., food stores) (e.g., interior lighting) shares of floorspace (%) saturations (%) energy intensities (e/ft ) industrial categories fuel categories value of shipments ($) (e.g., printing and publishing) (e.g., natural gas) category shares (%) energy intensities (e/$) other categories fuel categories gross state product ($) (e.g., street lights) (e.g., electricity) population energy intensities (e/$; e/person) electricity generation technologies fuel categories system load curve (e.g., steam turbine) (e.g., biomass) capacity (mw) base year output maximum capacity factor efficiency (%) fuel shares (%) merit order ( st– th) planning reserve margin (%) transmission and distribution losses (%) primary fuels natural gas, oil products, coal, nuclear, hydro, geothermal, biomass, wind, solar r. ghanadan, j.g. koomey / energy policy ( ) – . energy and greenhouse gas emissions calculations energy consumption for each demand sector is calculated using a set of equations built around technology energy intensities, saturation data, and activity drivers within each sector. energy consumption in the residential sector is calculated as the product of the total number of households, the saturation of the end use in residential households, the technology share of the end use, and the unit energy consumption of the given technology. total energy consumption is the sum of individual consumption of each of the different end- use technology categories. transportation consumption is calculated from the total passenger, freight, and air miles traveled, technology shares of transportation activity, and technology fuel economies. commercial consumption is based on the total commercial floor- space, the share of commercial floorspace of each building type, the saturations of end uses within each building type, and the fuel intensities on a square foot basis for each end use. the model calculations of industrial consumption are based on the total industrial value of shipments, sub-sector shares of total industrial value of shipments, and fuel intensities per shipping value for each sub-sector. the other demand sector is comprised of agriculture, streetlights, and transporta- tion, communications, and utilities. similarly, consump- tion is calculated from the activity parameter and fuel intensities per unit of activity. electricity generation is calculated to meet electricity demand requirements of the individual demand sectors. the electricity generation module uses explicitly speci- fied technology categories and attributes as well as a specified merit order, annual system load curve, and import and export requirements to meet the total annual electricity demand resulting from each set of scenario assumptions. the base year composition of generation technologies and generation output of california’s power sector is built from existing state-level power plant data. for these analyses, electricity losses from transmission and distribution were assumed to be %, and capacity additions were based on an optimal reserve margin of %. new capacity additions are added either exogenously or endogenously to the generation sector. article in press fig. . combined energy consumption of demand sectors in and for each scenario in in petajoules ( j)/yr. energy savings of the alternative scenarios relative to bau are also indicated for . note that combined energy consumption corresponds to final energy consumed within the demand sectors and therefore implicitly includes r. ghanadan, j.g. koomey / energy policy ( ) – exogenous capacity additions are planned additions with a specific quantity and type of capacity added at a specific time in the future. endogenous capacity addi- tions are specific technologies that are built as needed to meet the electricity consumption requirements as specified by the demand sectors. the greenhouse gas emissions associated with fuel consumption in california were estimated using average emissions factors for each sector and fuel type, accord- ing to ipcc guidelines for national greenhouse gas inventories and tier average emissions factors. the technology and environment database (ted) within the leap modeling platform directly links each technology within the supply and demand structure to an average emissions factor based on its sector and fuel use. total greenhouse gas emissions were calculated in terms of global warming potential in units of carbon dioxide equivalents. electricity generation including imports from outside of the state. . quantitative modeling results the quantitative scenario modeling results explore the implications of each scenario for future consumption of energy, composition of electricity generation, energy diversity, and greenhouse gas emissions. it is important to recognize that our discussion does not aim to advocate any particular scenario or make any distinct claims about how the future will actually unfold. rather, the results demonstrate a subset of the many activities and outcomes that are possible. we acknowl- edge that there are considerable uncertainties inherent in this type of analysis (particularly for scenario exercises extending over several decades), and the results must be considered in this context. these analyses represent an exercise that illustrates possibilities for the future in a way that strives to be quantitative and transparent. these scenario results aim to catalyze continued discussion of future choices and decisions that will shape california’s future. . combined energy consumption of demand sectors the combined final energy consumption of califor- nia’s residential, commercial, industrial, and other demand sectors is expected to increase steadily over the next decades under bau conditions. the composi- tion of state energy consumption reveals that the transportation sector makes up more than % of energy consumption in and continues to increase in absolute and relative terms under bau conditions through (fig. ). the remaining energy consump- tion is split between industry, residential, commercial, and other demand sectors, in decreasing order. each of the alternative scenarios demonstrates energy savings compared to bau in , with patriotic energy showing the greatest energy savings, followed by split public and then golden state. the largest component of these savings is derived from the transportation sector with residential and commercial sector activity savings making up smaller shares. alternative scenario activities in the industrial and other demand sector activities are not developed in these scenarios and represent an opportunity for future work. the absolute and relative size of transportation energy consumption brings to light the dominant role the transportation sector plays in defining california’s overall energy pathway. even under conditions of active transportation reform, the overall potential for state energy savings is constrained by increasing per capita driving activity, growing population, and other forms of non-road transportation such as shipping and air travel. it is perhaps surprising to note that even under the conditions of % and % penetration of hybrid and electric passenger vehicles by in split public and golden state, transportation energy consumption con- tinues to increase. these scenarios point to the critical importance of transportation policies and activities in california for managing levels of absolute energy consumption in the face of continued trends of increasing population and driving activity. these results show that transportation is california’s greatest energy challenge in terms of overall energy consumption. residential and commercial savings are also achieved in the alternative scenarios through energy efficiency and renewable energy activities. in our analysis, small- scale and distributed renewable energy-based electricity generation by households and commercial sectors are reported as demand offsets at the residential and commercial levels rather than within the state-level article in press table combined energy consumption: rates of growth, relative savings, and composition base year bau split public golden state patriotic energy energy consumption a (pj) , , growth rate (avg. annual % – ) — . % . % . % . % scenario savings savings (pj) in — — savings vs. bau (%) in — — % % % consumption share residential % % % % % transportation % % % % % commercial % % % % % industrial % % % % % other % % % % % total b % % % % % a combined energy consumption corresponds to final energy consumed within the demand sectors; electricity generation and electricity imports are represented within the consumption of each demand sector. b consumption shares may not sum to % due to rounding. r. ghanadan, j.g. koomey / energy policy ( ) – electricity generation sector. of the residential activities, adoption of solar water heaters has the greatest impact, representing more than % of total residential energy savings in , followed by solar home systems comprising % of savings, efficient lighting %, and greater clothesline use %. even an activity as mundane as use of clothes line drying for a quarter of household activity has a measurable effect on residential energy consumption, one reminder that wide-spread, small actions in a populous state like california can have measurable impacts (table ). fig. . composition of electricity generation by fuel source in and each scenario in . natural gas generation is expected to significantly increase in the bau and split public scenarios. golden state and patriotic energy reduce electricity imports and expand renewable energy-based generation to continue to meet % targets primarily from wind, geothermal, and biomass (biomass category also includes small amounts of digestor-gas, landfill gas, and municipal solid waste). renewables refers to renewable energy based electricity generation and does not include large hydroelectric generation. biomass also includes small amounts of digestor-gas, landfill gas, and municipal solid waste. . electricity generation the form of california’s future electricity sector is highly uncertain, and each scenario explores different configurations of key variables. the bau scenario explores post-energy crisis expectations leading to a significant fraction of new capacity being derived from natural gas. split public mirrors the electricity sector of the bau scenario; the scenario’s local and individual activities are assumed to be unable to exert influence over state-level private sector investment and state electricity planning. golden state explores conditions of assertive state renewable energy policy. patriotic energy reflects a national drive to develop non-fossil fuel energy resources. all of the future scenarios show increases in natural gas-based electricity generation. increases are most dramatic for the bau and split public scenarios. golden state and patriotic energy incorporate growing shares of electricity generation from renewable energy sources and a reduction of imports. in , almost % of the electricity generated to serve california consumption was derived from natural gas (fig. ). out-of-state electricity imports made up the next largest share, followed by hydro, nuclear, renew- ables, and coal/oil. the share of natural gas generation increases in bau and split public to approximately % of generation. in contrast, golden state and patriotic energy show increased shares of renewable energy generation, captured primarily as wind, geothermal, and biomass catalyzed by state or national rps policies implemented early in the scenario timescales. golden state implements and exceeds a state rps; patriotic article in press table composition of electricity generation in the base year in and scenarios in base year bau split public golden state patriotic energy generation (twh) generation shares (%) natural gas % % % % % renewable (non-hydro) % % % % % hydro % % % % % nuclear % % % % % coal/oil % % % % % imports % % % % % total a % % % % % a consumption shares may not sum to % due to rounding. it is important to note that the link between energy diversity and r. ghanadan, j.g. koomey / energy policy ( ) – energy also exceeds a national rps making california a leader in renewable-energy based electricity generation. the role of electricity imports is an important variable in california’s future power sector. fig. shows that in electricity imports accounted for slightly more than % of generation. between and , the fraction of imports relative to total electricity generation serving california electricity needs has ranged between % and % (cec, a). in this analysis, the dispatch methodology of the scenario modeling platform exam- ines the annual magnitude and composition of power generation and imports so as to meet a specified annual system electricity load curve. however, our analyses do not examine instantaneous cost and demand patterns, which would be required for a more detailed analysis of import conditions. the bau scenario sets a minimum level of imports equivalent to the current level of fixed-coal electricity imports. in this case, imports in addition to this minimum level occur only when the state cannot meet electricity demand with in-state generation. the bau approach explores the potential for electricity generated from new natural gas capacity to decrease overall import levels, suggesting that the level of proposed new construction in the post-energy crisis conditions has the potential to dramatically change the context for imports and for possible new renewable energy capacity particu- larly in the near term. the way that conditions and trade-offs for imports and capacity additions will actually play out is uncertain, however they clearly indicate the importance of examining system-wide effects inherent in the proposed capacity additions emerging from the post-energy crisis context. split public reflects the same power sector and import assumptions as the bau scenario with a slightly lower overall level of generation due to electricity conservation and self- generation in residential and commercial sectors. fixed coal imports serving california have averaged around , gwh or % of demand between and (cec, a). golden state and patriotic energy represent a different approach to future power sector development. both scenarios reduce overall electricity import level. this assumption is consistent with the logic that golden state’s integrated state planning places high value on develop- ment of a diversified generation system that can be managed by the state. increases in renewable energy generation and reductions in imports become important planning criteria in golden state and a part of the state’s strategy for meeting and exceeding its rps policy. under these conditions, imports decrease significantly from % in to % in . patriotic energy also demon- strates a decrease in imports. in this scenario, renewable- derived electricity from states rich in renewable resources becomes an important part of a national strategy to reduce the fossil fuel dependence of the nation’s electricity- sector and free up available fossil fuels for high value uses, such as heating and industrial processes. california develops its renewable-based generation primarily in the form of wind, geothermal, and biomass (table ). . implications for energy diversity energy diversity plays a role in supply security, financial risk, energy planning, and the environment. in california, increasing energy diversity is also linked to decreasing relative fossil fuel dependence. with the large fraction of state primary energy consumption attributed to oil and natural gas, and the state’s share of coal consumption unlikely to increase, energy consump- tion will only become more diverse if a greater proportion of state energy consumption is made up of non-fossil fuels. the analysis of the energy diversity of each scenario provides one indication of the extent to decreasing reliance on fossil fuels is not true in every energy system; it is only because of the particular circumstances of california with already large oil and natural gas fuel shares and limited potential growth of coal fuel shares that this claim can be made. article in press fig. . category shares of primary energy consumption in and for each scenario in . primary fuels as well as primary energy associated with electricity imports and energy savings (relative to the bau scenario in ) are included as separate category shares. r. ghanadan, j.g. koomey / energy policy ( ) – which the scenarios present alternatives to bau futures dominated by fossil fuel use. the composition of primary energy consumption is used as the primary basis for assessing the energy diversity of california’s energy system. fig. shows the largest fuel fractions of overall primary energy consump- tion to be attributed to oil and natural gas. fossil fuels accounted for % of primary energy consumption in , and their share increases under bau conditions to nearly % by (table ). the alternative scenarios demonstrate a decrease in the fraction of fossil fuels, with split public and golden state showing decreases in fossil fuel shares to % and %, respectively, and patriotic energy showing a dramatic reduction to %. demon- strating the dynamic of decreasing fossil fuel shares, energy diversity increases in split public, golden state, and patriotic energy. in the bau scenario, the opposite is true; fossil fuel shares increase, and energy diversity decreases between and . a simple index for diversity, based on the classic herfindhal measure of market concentration, provides a method to quantitatively examine the relationship between category shares and energy diversity (neff, ). the diversity index is calculated as h ¼ = x x i ; where xi is the category fraction from source ‘‘i’’. values of h range between and the total number of categories, and the higher the value of h; the greater the energy diversity. this analysis uses eight categories to calculate energy diversity, making the maximum possible value of h to be eight and minimum value to be one. the eight maximum diversity is achieved when all eight categories have equal shares, or h= =( �( / ) )� . minimum diversity corresponds to conditions when one category has a % share, thus h= =( ) � . categories used in the calculation include: oil products, natural gas, coal/coke, hydropower, nuclear, renew- ables, electricity imports, and energy savings. the argument for creating a category for electricity imports is the generally different risk profiles of electricity imports and in-state electricity generation. creating a separate category for energy savings makes it possible to incorporate both supply and demand opportunities for increasing energy diversity, recognizing that fossil fuel consumption can be displaced by supply shifts toward non-fossil fuels like renewables or demand changes to achieve energy savings through energy efficiency or conservation. the most notable result of these analyses is the loss of energy diversity between and under bau conditions evidenced by the decreasing index values (table ). significant increases in natural gas power generation and dramatic increases in transportation and oil consumption are the primary factors responsible for the loss of energy diversity. in contrast, all three alternative scenarios show gains in energy diversity compared to the bau scenario. the most diverse scenario is patriotic energy, followed by split public, and then golden state. energy diversity gains in golden state are achieved through diversification of the power sector and to a lesser extent through transportation and residential activities. split public achieves greater energy diversity than golden state largely through energy savings associated with greater activity in residential energy efficiency, renewable-based power generation, and hybrid and electric vehicle use. patriotic energy is the most diverse scenario as a result of sweeping transportation changes, diversification of the power sector, and residential and commercial efficiency and renewable energy activities. these results show that the key dynamic of increasing energy diversity is to reduce natural gas and oil dependence through energy savings and renewable energy activities. transportation and electricity genera- tion, with their direct association to oil and natural gas consumption, are critical sites for diversity activities. households, community, and industry also have a role to play. an integrated approach combining technology, policy, and individual choices is needed if the energy diversity of the state is to increase over the next decades. . implications for greenhouse gas emissions with a large population, driving-intensive lifestyle, and high level of economic activity, california accounts for a significant level of greenhouse gas emissions. the average californian is responsible for about three times renewables include wind, solar, geothermal, small-hydro, bio- mass, digestor gas, landfill gas, municipal solid waste, and hydrogen. article in press table primary energy consumption and scenario diversity index base year bau split public golden state patriotic energy diversity index, h . . . . . primary energy consumption (pj) a , , , , electricity imports b % % % % % oil products % % % % % coal and coke % % % % % natural gas % % % % % hydro % % % % % renewables % % % % % nuclear % % % % % savings vs. bau ( ) — — % % % total c % % % % % a total primary energy accounts for direct consumption of primary fuels by demand sectors and electricity generation (i.e. it accounts for natural gas used to generate electricity, not electricity itself). b the primary energy consumption associated with electricity imports is estimated assuming % conversion efficiency of primary energy to electricity that is then imported into california from other states. c consumption shares may not sum to % due to rounding. fig. . greenhouse gas emissions in california, the us, and the world, on a gross and per capita basis in . california emissions estimates include only in-state emissions. accounting for electricity imports from outside of the state is estimated to increase gross state emissions on the order of – % in . sources include (cec, f; eia, f, g; us census, c). r. ghanadan, j.g. koomey / energy policy ( ) – the carbon dioxide emissions of the average world citizen (fig. ). if california were a country, it would rank approximately th in terms of total carbon dioxide emissions. including out-of-state fuel generation in the form of electricity imports, a measurable component of which are derived from coal, california would assume an even greater share of global emissions. reducing absolute and per capita emissions will require alternatives to current trends. to explore opportunities for change, this analysis investigates the greenhouse gas implications of the scenarios and considers their potential for mitigating emissions. our emissions calculations are based on ipcc tier one emissions factors and fuel consumption in each sector. we first focus on in-state emissions, and then treat the emissions from imported electricity in a sensitivity analysis (emissions from imports are subject to a substantial amount of uncertainty). fig. shows the magnitude and composition of in- state greenhouse gas emissions by sector in and each scenario in . in-state greenhouse gas emissions in are estimated to be million metric tons of carbon dioxide equivalents. this value is estimated to increase more than % by in the bau scenario. split public, golden state, and patriotic energy show lower rates of emissions increases. comparing scenario emissions to levels provides a reference to kyoto protocol targets. using a california energy commis- sion estimate of gross emissions of million metric tons carbon dioxide equivalents (cec, f), bau, split public, golden state, and patriotic energy emissions in are %, %, %, and % above this estimate is based on values presented in fig. . levels (table ). these results illustrate the sensitivities of the small set of activities incorporated into each scenario for emissions reductions; these results should not be viewed as indicative of the full potential for greenhouse gas mitigation in the state. comprehen- sive mitigation scenarios would require a much more detailed set of modeled mitigation activities than are incorporated into these scenarios as well as an analysis of the combustion and non-combustion related emis- sions and sinks. looking at sector shares, greenhouse gas emissions in california are dominated by transportation. in , the transportation sector accounts for more than % of emissions (table ). transportation emissions continue article in press table total in-state greenhouse gas emissions (million metric tons co equivalents) % change % change a – – bau split public golden state patriotic energy a source: (cec ( f). fig. . in-state greenhouse gas emissions by sector in and scenario in in million metric tons of carbon dioxide equivalents. in-state emissions are estimated to increase more than % by in the bau scenario. split public, golden state, and patriotic energy demonstrate more moderate increases of %, %, and %. accounting for electricity imports from outside of the state is estimated to increase total state emissions on the order of – % in and – % in . note these scenarios do not represent the complete suite of multi-sector emissions mitigation activities that might be possible in california’s future energy system. as a result, the sensitivities of emissions reductions relative to the bau scenario are the most meaningful dimension, rather than absolute magnitudes of scenario emissions profiles. r. ghanadan, j.g. koomey / energy policy ( ) – to increase in the bau, split public, and golden state scenarios. only the patriotic energy scenario shows a decrease in transportation emissions. it is interesting to note that even the % and % penetration of hybrid and electric passenger vehicles in split public and golden state are not sufficient to offset increasing emissions due to population growth, freight growth, and increasing driving activity. only in patriotic energy, where fossil fuel powered cars and light duty trucks are fully displaced by fuel cells, hybrid, and electric vehicles and aggressive freight fuel economy standards are adopted do transportation emissions decrease in abso- lute and relative terms. these results suggest that transportation needs the greatest attention if the state is to mitigate its greenhouse gas emissions. an important step in this direction is the passage into law of a much debated bill in july requiring the california air resources board to adopt regulations to reduce the emissions of greenhouse gases by motor vehicles (california legislative counsel, , assembly bill ). this new law promises to create a base of authority and information that will be needed to begin to address the emissions from cars and trucks in california. another important result is the potential for decreas- ing emissions associated with diversification of the state’s power sector to incorporate a greater share of renewable energy. in the bau scenario, in-state emissions from electricity generation in increase by % from levels as a result of increasing electricity demand and increasing shares of natural-gas generation. golden state has a more diversified genera- tion sector and demonstrates an % increase in emissions compared to . this difference is primarily attributed to a decrease in the expected natural gas capacity additions in golden state as a result of electricity savings in residential and commercial sectors and an increase in renewable energy generation to make up this difference in capacity. imports from outside the state are an important and challenging dimension of california greenhouse gas emissions accounting. between and , califor- nia imported between % and % of its electricity requirements; – % of state electricity demand was served with imports from the pacific northwest and southwest and – % from investor-owned, out of state coal generation plants that supply electricity exclusively to california (cec, a). these emissions are a critical part of accurate accounting of california’s inventory of greenhouse gas emissions. in particular, imports from out-of-state coal-fired power plants serving california demand represent a measurable component of emissions associated with california’s actual energy services. to make a first level approximation of greenhouse gas emissions for electricity imports, we use a set of simple assumptions to estimate the high and low emissions limits which would bracket the actual value of import emissions. the low emissions limit assumes conditions where the only imports emissions come from fixed-coal generation. the level of fixed-coal imports is assumed to remain constant at approximately levels through- out the scenarios ( , gwh). the low emissions limit assumes that the – % of electricity requirements that are imported from the pacific northwest and southwest are non-emitting, and the rest are from coal-fired power plants. the high emissions limit assumes that all imports are from coal-fired power plants. import levels vary depending on the scenario import assumptions. based on low and high emissions limit calculations, electricity imports would increase electricity sector emissions estimates in the range of – % in and – % in the bau scenario in (table ). article in press table greenhouse gas emission estimates for in-state electricity generation and electricity imports (million metric tons co equivalents) base year bau split public golden state patriotic energy in-state electricity generation emissions electricity imports emissions estimate a low emissions limit b % of in-state electricity emissions % % % % % high emissions limit c % of in-state electricity emissions % % % % % estimated increase in total state emissions from electricity imports accounting d base year, – % scenarios, – % a calculations use electricity generation emissions factor for coal-derived electricity of . metric tons co /tj coal consumed and % conversion efficiency for coal-fired power plants. b low emissions limit assumes the first , gwh of electricity imports come from coal derived electricity (equivalent to year fixed-coal imports), any additional imports assumed non-emitting. c high emissions limit assumes all electricity imports are derived from coal-fired power plants, actual emissions associated with imports would fall somewhere between the low and high emissions limit. d values represent the increase in total state emissions that would result from including the range of low and high emissions estimates for electricity imports in and all of the scenarios in . table in-state greenhouse gas emissions and change by sector, and (million metric tons co equivalents) base year bau split public golden state patriotic energy in-state emissions sector emissions residential transportation commercial industry other electricity generation a % change – residential � % � % � % � % transportation % % % � % commercial % % % % industry % % % % other % % % % electricity generation % % % % total % % % % a electricity generation emissions are only for in-state emissions and do not include emissions associated with imported electricity. accounting for electricity imports from outside of the state is estimated to increase total state emissions on the order of – % in and – % in (see table ). r. ghanadan, j.g. koomey / energy policy ( ) – recognizing that non-fixed imports from the pacific northwest and southwest come from hydro, natural gas, coal, and other sources, the actual emissions contribution of imports would be higher than the low limit. accounting for electricity imports from outside of the state is estimated to increase gross state emissions on the order of – % in and – % in (see table ). these values represent the increase in total state emissions that would result from including the range of low and high emissions estimates for electricity imports in and all of the scenarios in . these results emphasize the importance of compre- hensive accounting of state greenhouse gas emissions. particular attention needs to be paid to transportation, article in press r. ghanadan, j.g. koomey / energy policy ( ) – electricity generation, and electricity imports. mitigation of state emissions will require systematic information, monitoring, and policy incentives. climate change promises to be one of the most profound challenges to california’s energy pathway. these analyses represent a first step toward examining mitigation options for the future. . lessons, opportunities, and policy implications california energy scenarios are a visioning tool that provides an opportunity to explore the context of current choices and priorities for the future. this paper concludes by presenting a summary of important policy lessons, opportunities, and policy implications that emerge from the scenario analysis. these ideas synthe- size scenario findings and represent a call for active and critical examination of the context and implications of future choices in california. . california is on a fossil fuel pathway. california’s bau pathway reveals decreasing energy diversity and increasing fossil fuel dependence. currently, fossil fuels comprise more than % of primary energy demand. expectations of increasing numbers of vehicles, greater driving activity, and construction of natural gas power plants would take california down a pathway toward even greater reliance on fossil fuels. scenario analysis shows that energy savings, renewable energy, and transportation activities provide critical opportunities for achieving more diverse energy pathways. . transportation is the major energy consumer and emitter of greenhouse gases in the state. transportation accounts for more than half of state energy consumption and greenhouse gas emissions. this sector also bears responsibility for state oil dependence and local air quality and land use concerns. cars and trucks are the most energy-intensive technology an average person owns—and california has almost as many cars as people. under bau conditions, transportation activity and energy consumption are expected to grow substan- tially faster than either population or the economy. the sheer number of vehicles and magnitude of driving activity also means that small changes have measurable impacts. transportation policies, consumer preferences, or technologies that serve to increase fuel economy, decrease driving activity, or promote alter- native fuel use offer large opportunities for reducing future energy consumption, decreasing pollution, and increasing energy diversity. the magnitude, impacts, and risks of transportation activities and oil consumption provide hearty justification for assertive transportation policy and planning on state and federal levels. . the diversity of california’s future electric power sector is highly uncertain. natural gas generation currently accounts for nearly % of generation serving california electricity demand. the future composition of california’s power sector is uncertain, and current activities and expectations lead in competing directions. long-term electricity contracts, largely for natural gas- based generation, negotiated during california’s energy crisis promise to exert a major influence over the composition of electricity generation over the next years. post-energy crisis expectations for significant new natural gas capacity additions also reinforce the potential for dramatic increases in natural gas depen- dence. at the same time, the state’s new rps policy and increasing renewable energy activity in residential and municipal areas also assert the importance of renewable energy in the state’s future. california currently has come to a cross-roads in its electricity sector, and the next decade will be a critical period in determining whether the state chooses a pathway of greater or decreasing energy diversity. . alternative pathways to bau expectations are relevant and deserve attention. california has a history of being a leader in energy innovation and policy, and is recognized for pursuing alternative pathways. the state now faces the challenge of continuing this legacy under the changing conditions of post-energy crisis. with a combination of public interest, industry cooperation, and policy leadership, california has enormous oppor- tunities for pursuing cleaner energy pathways on both local and regional levels. as the pressures associated with continuing down a fossil fuel pathway continue to increase, alternative pathways will likely be viewed as even less ‘‘alternative’’ and more ‘‘necessary’’ in the future. recognizing the value of alternatives earlier in its energy pathway offers even greater gains from earlier adoption. scenarios offer a starting point for examining alternatives. . individual and community activities can and do make a difference. the scenarios show that consumer prefer- ences, household energy use, and community activities have a measurable impact on reducing energy consump- tion and increasing energy diversity. use of solar water heaters, residential home and commercial solar electri- city generation, energy efficiency, and fuel efficient and/ or alternative fuel vehicle choices are some important ways that individuals and communities can and do make a difference to california’s energy system. community leadership may become one of the most critical driving forces for change in the future. . imports play an important role in state electricity generation and greenhouse gas emissions. energy imports exert a major influence on the availability, composition, and emissions associated with electricity generation serving demand in california. with the potential for natural gas capacity additions and the implementation of a new rps policy, the role of electricity imports promises to be an area of extensive uncertainty. article in press r. ghanadan, j.g. koomey / energy policy ( ) – consideration of the future influence of imports in california on costs, reliability, and greenhouse gas emissions are important areas of focus for the future. an area that is critically important is for state-level greenhouse gas emissions reductions and mitigation activities to take into account not only in-state genera- tion but also imports, as a measurable component of imports are derived from coal-based generation. only by including all of its energy sources will accurate benefits and trade-offs of different climate change mitigation strategies be able to be assessed and implemented. california has the opportunity to take the lead in facilitating cooperative and planning efforts within the region. . a combination of household, local, state, and national approaches offers the greatest gains in energy diversity. scenario analysis shows that the greatest decreases in energy consumption, increases in energy diversity, and reductions in greenhouse gas emissions are achieved from combining both state and national policy with individual and community activities. the level of individual responsibility and state planning are both important factors in the state’s pathway. california has vast opportunities for encouraging and facilitating a combination of household, community, and centralized energy activities. national policy and incentives parti- cularly in transportation also have a critical role in influencing california energy use. state, national, community, and individual actors share responsibility for shaping california’s future energy pathway. . a state renewable energy plan can provide a roadmap for the future. for california to remain a leader in renewable energy and catalyze a supportive investment environment, the state needs to assert its commitment to renewable energy and transparently articulate the ways it will encourage these activities. the recent passage of a california rps is an important step in this direction. the state now has the opportunity to develop a comprehensive, long-term vision for renewable energy policy and planning with participation of the public, industry, and other stakeholders. the rps provides the ideal flagship energy policy for beginning this process of creating a state renewable energy framework and vision for future policy and planning. the form of incentives, purchasing contracts, standardization of interconnec- tions, and utility cooperation are critically important areas for the future. . energy savings can play an important role in a california clean energy pathway. demand-side energy savings offer important opportunities for decreasing fossil fuel dependence, offsetting pollution, and increas- ing energy security. as a complement to supply side approaches, energy savings have an important role to play in california (rufo and coito, ). equally important is the recognition that energy savings involve both energy efficiency and decreasing energy consump- tion, as both technologies and social choices have a role to play in california’s energy pathway. transportation offers the greatest opportunities for energy savings measures, for example increasing fuel economies of passenger and freight vehicles, development of alternative fuel vehicles and immediate low-tech options of walking, biking, public transit and increasing rider numbers per vehicle. energy savings and energy efficiency are the most secure and least environmentally disruptive forms of energy ‘‘supply’’. increasing the ability of individual and state planners to consider savings both from technologies and increasing social choices is important to realizing alternative pathways. . long-term visioning and cooperation starts now. california has the opportunity to learn from its years of experience in energy policy and planning. a critical lesson from the past is that policy vision and public leadership have inspired many of california’s most highly regarded energy activities. in order for a new vision to emerge, it is necessary for the public, industry, government, and other critical stake holders to engage with the future. state leadership is needed to facilitate active discussion, participation, and consideration of alternatives for the future. now is a critical time for the state to reorganize its energy planning activities, reassert its mandate for information gathering, and incorporate new ideas into its planning and forecasting purview. . conclusions historically on the forefront of energy policy and technologies, california is, in many ways, both an example and indicator of the potential direction for future energy policy. perhaps most significantly, cali- fornia has conducted one of the most visible and highly scrutinized experiments in electricity deregulation in the world. interpretation of california’s deregulation ex- perience and the success or failure of the state’s subsequent energy pathway will have far-reaching implications for the future of energy policy both domestically and internationally. both the uncertainty and significance of california’s current energy context validate the importance of the state’s energy pathway. expectations of how the forces of electricity deregulation were to shape the state’s energy system have been turned on their head by the energy crisis. they have left in their place significant uncertainty about the future, where a unified and integrated vision for the future has yet to emerge. california currently faces a cross-roads in its energy pathway, and it is important to ask: how will the state move forward into the next years? what priorities will shape california’s energy system? how might leadership emerge? what can be learned for making better decisions today? article in press r. ghanadan, j.g. koomey / energy policy ( ) – the scenarios presented here respond to these questions and demonstrate that plausible alternative energy pathways do exist. they do not predict what the future will be or even what it should be like. rather they open the doorway to possibilities. the methods, tools, and examples presented here are a starting framework for beginning this discussion and an opportunity for creative engagement with the future. acknowledgements the project, which is a modified version of rebecca ghanadan’s master’s thesis, benefited from the support of the nautilus institute for security and sustainable development in developing the california dataset and scenario modeling framework. the project was also supported by the energy foundation through the renewable and appropriate energy laboratory at the university of california berkeley. we thank peter hayes, david von hipple, masami nakata, and megan keever of nautilus institute for providing the colla- borative environment for initiating this project. we thank daniel kammen for his technical input to the project design and review of the manuscript. we thank table scenario attributes split public golden st residential solar pv a household penetration, % % total pv generation, twh . twh implied total capacity gwp gwp implied market sales growth %/yr %/yr assumptions continuation of california energy co a) continuation of net metering legislatio ) background data and supporting studies ca grid-connected pv capacity inst ca buydown program: mwp smal (cec, b) ca expected buydown growth: addit study of economics of solar pv indus doubling of production based on litera study of solar grid-connected pv mark drop $ /wp to $ . /wp, global pv s production (implied learning rate of transportation penetration, hybrid and electric vehicles % % the many energy researchers who provided data and information to the california energy dataset. in particular, lynn marshall, andrea gough, and gary occhuizzo of the california energy commission de- mand analysis office and luk lee from the california department of transportation were instrumental in providing historical and forecast demand data for the industrial, commercial, and transportation sectors. timothy lipman of the renewable and appropriate energy laboratory at the university of california berkeley contributed expertise and insight in developing the transportation sector. matthias fripp provided data on california wind potentials. we thank charlie heaps of the stockholm environment institute boston center for his valuable modeling advice and assistance in developing the california leap modeling platform. appendix a. background and assumptions for key scenario elements a detailed treatment of background assumptions and justification for the scenario elements is summarized in table . additional references ate patriotic energy % twh gwp kw systems, . million households in , based on . % population growth/yr %/yr %/yr global pv market sales growth since (duke, ) mmission’s emerging renewables (buy-down) program (see cec, n systems p mw (california legislative counsel, , assembly bill alled: mwp (cec, c) l grid-connected pv installed; mwp in processing, as of / / ional mwp installed over next years (duke, ) try learning curves estimates historical learning rate of % for each ture review (see duke and kammen, ) et potential under pv buydown scenario. by module retail prices ales x gwp/yr, corresponding to doublings of cumulative %) (see duke, ) %, (continued on next page) article in press table (continued) scenario attributes additional references split public golden state patriotic energy %, fuel cell vehicles % % % assumptions manufacturing costs reductions, production scale economies, technological experience curves (see lipman et al., ) background data and supporting studies scenario study of fleet-wide vehicle manufacturing costs and retail prices, total lifecycle costs of vehicle ownership and operation, vehicle running and upstream emissions, and emissions control and damage costs from to , based on ca south coast air basin (see lipman et al., ) scenarios (lipman et al., ): high gasoline hybrid vehicle (hev): > % penetration by medium fuel cell electric (fcev): hev > %, fcev > % by high fuel cell electric (fcev): fcev > %, battery ev b % by result (lipman et al., ): high hev is win–win scenario with lifecycle ownership and operation cost savings and modest emissions reductions versus conventional vehicles (fuel savings exceed difference in manufacturing cost of $ – $ ) high-volume production costs of fcevs remain above conventional vehicles; lifecycle costs comparable at b$ . – . /gal of gasoline. at $ . /gal, high fcev scenario yields slightly lower lifecycle based vehicle plus emissions plus infrastructure costs (� . %) than conventional vehicle scenario. at $ . /gal, incremental lifecycle costs increase %. commercial a cumulative additions, wind mw mw mw solar mw mw mw total generation, wind . twh . twh . twh solar . twh . twh . twh assumptions expansion of municipal renewable energy initiatives following model of san francisco propositions b and h, expected to finance mw of solar and mw wind (california solar center, a, b) california municipal initiatives have large potential; san francisco represents approximately % of the state population; ca has cities with > , people and cities > , (city population california, ) implied expansion factor: relative to san francisco initiatives electricity a total generation, twh twh twh natural gas (twh) (% total) ( %) ( %) ( %) renewables (non-hydro) ( %) ( %) ( %) wind (twh) (%) ( %) ( %) ( %) geothermal (twh) (%) ( %) ( %) ( %) biomass b (twh) (%) ( %) ( %) ( %) assumptions natural gas additions for bau and split public derived from cec’s ‘‘most likely’’ and ‘‘baseline’’ scenario categories (cec, b, table i- , ii- - ) renewables generation shares based on california energy commission renewable energy resource assessment scenario ( % wind, % geothermal, % biomass) (see cec, d, ) continuation of national wind production tax credit, . cents/kwh golden state: ca renewable portfolio standard (rps) law as of / , % by (california legislative counsel, , senate bill ) patriotic energy scenario national rps of % by background data and supporting studies california renewable energy resource assessment estimated range of renewable generation potentials, based on various studies (see cec, d): wind: – twh/yr geothermal: – twh/yr biomass: – twh/yr solar: – twh/yr study quantifying m wind power from m measurements finds us wind power may be substantially greater than previously estimated. winds over possibly one fifth of the us are strong enough to provide electric power at a direct cost equal to that of a new natural gas or coal power plant. ca ranks th in numbers of x class sites (archer and jacobson, ) estimate ca on-land wind potential (awea, ): twh/yr, gw r. ghanadan, j.g. koomey / energy policy ( ) – article in press appendix b. sources of the california energy dataset the sources used to develop the california energy database are referenced in table table (continued) scenario attributes additional references split public golden state patriotic energy ca wind generation potential study (see land and water fund of the rockies, northwest sustainable energy for economic development and greeninfo network, ): based on ca data (considered conservative estimates) ca wind-derived on-land potential (xclass sites): twh/yr ca wind development potential land area (xclass ): , acres key sites in ca include: solano county, altamont pass, pacheo pass, san gorgonio pass, tehachapi, and others a small-scale distributed generation of electricity within the residential and commercial sectors from solar pv and wind are modeled within residential and commercial demand sectors themselves rather than within the electricity sector. modeling in this way makes it possible to track the level of electricity demand that is offset, or more accurately, relocated from within the state electricity system to self-generation within the residential and commercial sectors. residences and businesses are assumed to remain net consumers rather than producers of electricity. b biomass category also includes a small amount of digestor gas, landfill gas, and municipal solid waste. table category source residential eia ( , b, b), pg&e ( ), rlw analytics ( ), and wenzel et al. ( ) transportation bts ( ), caltrans ( , ), carb ( ), cec ( b, a, c, d), eia ( a, a, c, e), fha ( ), levin et al. ( ), lipman et al. ( ), mark and morey ( ) and pg&e ( ) commercial adm associates ( ), bea ( ), cec ( c) and xenergy ( ) industrial bea ( ), cec ( e) and xenergy ( ) electricity generation bachrach ( ), brown and koomey ( ), cec ( c, b, d, g, h, a, b, g, h), eia ( c, d, a, b) and epa ( ) emissions cec ( f, f), eia ( f), epa ( ), ipcc ( ) and nakicenovic and swart ( ) multiple sectors/fuels cec ( , , a, b, f, b), eia ( d, h) and schipper and mcmahon ( ) population and economy bea ( ), eia ( g); laedc ( ) and us census ( a, b, c, ) r. ghanadan, j.g. koomey / energy policy ( ) – appendix c. scenarios resources scenarios resources (see table ). table sector category source scenario planning and forecasting methods ascher ( ), de geus ( ), kleiner ( ), ringland ( a, b), schwartz ( ), van der heijden ( ) and wack ( a, b) energy and environment scenarios brown et al. ( ), gallopin and raskin ( ), ghanadan ( ), gumerman et al. ( ), harris ( ), interlaboratory working group ( ), lovins ( ), nakicenovic and swart ( ), raskin et al. ( , ), ross ( ), schipper and meyers ( ), shell ( , , ) and world business council for sustainable development ( ) future energy trends clean edge ( ), clemmer et al. ( ), dunn ( ), makower and pernick ( ), nep ( ), reddy et al. 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for pacific gas and electric company by xenergy, inc. xenergy, . commercial sector energy efficiency potential study (vol. i; vol. ii: appendices a–j). prepared for the pacific gas and electric company by xenergy, inc., draft final report, may . 	using energy scenarios to explore alternative energy pathways in california 	introduction 	the scenario approach 	developing the exploratory scenarios 	base case storyline-bau scenario 	alternative storyline -split public scenario 	alternative storyline -golden state scenario 	alternative storyline -patriotic energy independence scenario 	basis for scenario modeling 	the analytical framework 	energy and greenhouse gas emissions calculations 	quantitative modeling results 	combined energy consumption of demand sectors 	electricity generation 	implications for energy diversity 	implications for greenhouse gas emissions 	lessons, opportunities, and policy implications 	conclusions 	acknowledgements 	background and assumptions for key scenario elements 	scenarios resources 	sources of the california energy dataset 	references dynamic behavior of a stand-alone hybrid power generation system of wind turbine, microturbine, solar array and battery storage applied energy ( ) – contents lists available at sciencedirect applied energy j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / a p e n e r g y dynamic behavior of a stand-alone hybrid power generation system of wind turbine, microturbine, solar array and battery storage m. kalantar *, s.m. mousavi g. center of excellence for power system automation and operation, department of electrical engineering, iran university of science and technology, narmak, tehran, iran a r t i c l e i n f o a b s t r a c t article history: received april received in revised form january accepted february available online april keywords: wind turbine solar array microturbine adaptive control supervisory control indirect space vector control - /$ - see front matter � elsevier ltd. a doi: . /j.apenergy. . . * corresponding author. tel.: + x e-mail address: kalantar@iust.ac.ir (m. kalantar). this paper presents dynamic behavior and simulation results in a stand-alone hybrid power generation system of wind turbine, microturbine, solar array and battery storage. the hybrid system consists of a kw wind turbine, an kw solar array; a kw microturbine and a . kah lead acid battery pack optimized based on economic analysis using genetic algorithm (ga). at first, a developed lyapu- nov model reference adaptive feedback linearization method accompanied by an indirect space vector control is applied for extraction of maximum energy from a variable speed wind power generation sys- tem. then, a fuzzy logic controller is designed for the mentioned purpose and its performance is com- pared with the proposed adaptive controller. for meeting more load demands, the solar array is integrated with the wind turbine. in addition, the microturbine and the battery storage are combined with the wind and solar power generation system as a backup to satisfy the load demand under all conditions. a supervisory controller is designed in order to manage energy between the maximum energy cap- tured from the wind turbine/solar arrays, and consumed energies of the load, dump load, battery state of charge (soc), and generated energy by the microturbine. dynamic modeling and simulation are accomplished using matlab simulink™ . . � elsevier ltd. all rights reserved. . introduction renewable energy resources, called sustainable or alternative energy, are energies generated from natural resources such as wind, sunlight, tide, hydro, biomass and geothermal which are naturally replenished. energy crisis, climate changes such as atmosphere temperature rise due to the increase of greenhouse gases emission and the kyoto protocol restrictions in generation of these gases, coupled with high oil prices, limitation and deple- tion of fossil fuels reserves make renewable energies more noticeable. moreover, since many remote rural areas in all over the world are not electrified, for example about million households in rural india do not have access to electricity [ ], one of the interesting utilization of the renewable energies is to electrify many remote villages and rural areas or rugged ter- rain located so far from power stations and distribution net- works or utility lines which are uneconomical to install. vulnerability to unpredictable climatic changes and dependency of renewable energy systems on weather conditions remain among their drawbacks. ll rights reserved. ; fax: + . . literature review among the renewable energy resources, wind power has had the fastest growth in the world (at the rate of % annually) in many developed and developing countries over the last years [ ]. for example, installed capacity in germany is more than gw with an annual output of about twh in [ ]. in or- der to convert the wind energy to electrical energy, two types of wind turbines are employed; fixed speed and variable speed wind turbines installed onshore or offshore [ ]. in the fixed speed wind turbine, electrical generator is connected directly to the power grid. therefore, the generator runs at constant frequency and speed. active and reactive power control of these turbines is de- scribed in [ , ]. the variable speed wind turbine (vswt) is used for more attraction of energy from the wind. the vswt, which at- tracts – % more energy, has lower mechanical stress and less power fluctuation in comparison with the fixed speed ones. fur- thermore, the wind turbine is divided into two large categories: horizontal and vertical axis wind turbines. savonius and sherbious are the most famous vertical axis wind turbines (vawt). the aero- dynamic efficiency of the vawt is lower than the horizontal type but complexity and price of these types are lower [ ]. one of the most important studies in the vswt is the applica- tion of various control schemes for several purposes in the plant. http://dx.doi.org/ . /j.apenergy. . . mailto:kalantar@iust.ac.ir http://www.sciencedirect.com/science/journal/ http://www.elsevier.com/locate/apenergy 	dynamic behavior of a stand-alone hybrid power generation system of wind turbine, microturbine, solar array and battery storage 	introduction 	literature review 	proposed system description 	wind energy conversion system 	solar array model 	microturbine model 	battery storage model 	control systems design 	indirect space vector control, fuzzy logic controller, feedback linearization, and developed model reference adaptive controller design 	indirect space vector control 	feedback linearization and developed model reference adaptive controllers design 	fuzzy logic controllers design 	supervisory controller 	optimal sizing and economic analysis 	the annualized capital cost 	annualized replacement cost 	annualized fuel cost 	annualized operation and maintenance cost 	simulation results and discussion 	conclusions 	references untitled letters an unexpected cooling effect in saturn’s upper atmosphere c. g. a. smith , a. d. aylward , g. h. millward {, s. miller & l. e. moore the upper atmospheres of the four solar system giant planets exhibit high temperatures , that cannot be explained by the absorption of sunlight , . in the case of saturn the temperatures predicted by models of solar heating , are k, compared to temperatures of k observed independently in the polar regions and at latitude . this unexplained ‘energy crisis’ represents a major gap in our understanding of these planets’ atmospheres. an important candidate for the source of the missing energy is the magnetosphere , , , – , which injects energy mostly in the polar regions of the planet. this polar energy input is believed to be sufficient to explain the observed temperatures , provided that it is efficiently redistributed globally by winds , , a process that is not well understood. here we show, using a numerical model , that the net effect of the winds driven by the polar energy inputs is not to heat but to cool the low-latitude thermosphere. this surprising result allows us to rule out known polar energy inputs as the solution to the energy crisis at saturn. there is either an unknown—and large—source of polar energy, or, more prob- ably, some other process heats low latitudes directly. recent numerical modelling studies , have shown that under spe- cific circumstances polar energy inputs may explain the high thermo- spheric temperatures at saturn. for plausible heating distributions in the polar regions there is predicted to exist a system of equatorward winds that redistribute the energy globally, generating the observed temperatures at both low and high latitudes. but these studies con- sider only the effects of pure thermal energy inputs on the ther- mosphere, whereas the bulk of the polar energy input from the magnetosphere is thought to be a mixture of thermal energy (joule heating) and kinetic energy (ion drag) in roughly equal propor- tions , . the kinetic energy input is necessarily accompanied by an input of angular momentum. the sense of this angular momentum input is westward, that is, in the opposite direction to that of the planetary rotation. the overall effect of ion drag on the dynamics is thus expected to be the generation of strong westward winds throughout the polar thermosphere. here we address for the first time to our knowledge the effect of these westward winds on the structure of the thermosphere. we use a numerical thermosphere model based on a widely used model of the terrestrial thermosphere , converted to an atmosphere composed of h , h and he. it uses an eulerian grid on which temp- eratures and the three components of the neutral wind are calculated by time integration. the lower boundary is placed at an altitude of km above the bar level, and at a fixed pressure of nbar. at this level we assume a fixed temperature of k (ref. ) and a horizontal wind velocity of zero. we parameterize the vertical trans- port of energy and momentum by small-scale motions using an eddy diffusion coefficient of kt m s . for this study, we simplify the model by assuming that the system is symmetric about the planet’s axis of rotation and mirror-symmetric about the equatorial plane. these are good approximations because saturn’s magnetic field almost exhibits both of these symmetries . furthermore, the dynamics of the magnetosphere are strongly dominated by the plan- etary rotation and can be approximated as axially symmetric to first order . we expect deviations from our assumed symmetries to be second-order effects. we note that the introduction of axial sym- metry does not mean that we do not model zonal (east–west) winds: the effects of zonal winds are fully included in the model, but they are assumed to be identical at all longitudes. the introduction of these symmetry assumptions allows us to use very high grid resolutions in our model. we employ a latitudinal resolution of . u and a vertical resolution of . pressure scale heights. further details and discussion of the model are given in the supplementary methods. this basic model is forced only by solar heating. running this model to near steady state (requiring a run time of planetary rotations ) predicts roughly uniform global temperatures of , – k (supplementary fig. ), with the higher temperatures at the equator. to include the polar energy inputs, we require models of the ionospheric conductivity and plasma flows. good empirical models of the ionospheric conductivity do not exist, owing to lack of data. for this reason we use a conductivity distribution calculated using a numerical model of the ionosphere . we use ion and electron densi- ties from this model to calculate a global distribution of conductivity and fix these values with respect to our thermosphere model. the ionospheric plasma flows are taken from an empirical model based on a mixture of in situ spacecraft and ground-based spectroscopic data . this model predicts that the magnetosphere will exert a west- ward ion drag on the thermosphere poleward of , u latitude. thus we expect the joule heating and ion drag to be significant only in this region. further details of both these models, and our formulation of joule heating and ion drag, are given in the supplementary methods. including these inputs in the model generates the structures shown in fig. . comparing this run to the control run forced only by solar heating shows that joule heating and ion drag cause net heating poleward of and net cooling equatorward of the dashed line. the maximum cooling effect is , k at , u latitude. although small, this effect is unexpected, counter-intuitive and rather surprising. it can be explained by inspecting the meridional circulation, which shows a poleward flow at low altitudes and an equatorward flow at high altitudes. the low-altitude flow is energetically the more important because the density of the atmosphere decreases with increasing altitude. thus the dynamical coupling between low and high latitudes is dominated by a steady flow of gas—and therefore energy—away from low latitudes and into the polar regions. this acts both to enhance convective cooling of low latitudes, and to heat the polar region. the flows themselves arise because of small force imbalances in the thermosphere. in fig. we show a conceptual department of physics and astronomy, university college london, wc e bt, uk. center for space physics, boston university, boston, massachusetts , usa. {present address: laboratory for atmospheric and space physics, university of colorado, boulder, colorado , usa. vol | january | doi: . /nature nature © publishing group interpretation of these flows in terms of the hydrostatic balance in the upper atmosphere; in the supplementary discussion we also present an analysis of the actual forces calculated by the model. it is clear from fig. that, while our model does reproduce the observed temperature of , k in the polar regions , we do not reproduce the observed value of , k at u latitude , because we predict cooling everywhere equatorward of u latitude. the initial indication is thus that the polar energy inputs resolve the high-latitude energy crisis but do not resolve the low-latitude energy crisis. however, we must consider whether our results depend on our choice of model inputs. the input in which we have the least con- fidence is the ionospheric conductivity model: while our thermo- spheric boundary conditions and plasma flow model are well supported by the available data, the conductivity model is not. in particular, the model currently only includes ionization due to absorption of solar radiation, and so it most probably underestimates the conductivity in the polar regions, where particle precipitation is an important source of ionization. we have thus performed a sens- itivity study in which we artificially scale up the conductivity globally by fixed factors. the effect of this alteration is simply to intensify the behaviour described above. if the scaling factor is , the polar hot- spot reaches temperatures greater than k and the maximum degree of cooling compared to the control run increases to , k (see the supplementary discussion for further details). thus we still approximately match the observed high-latitude temperature and still fail to match the observed low-latitude temperature. a , a lt it u d e a b o ve b a r (k m ) , , latitude (°) temperature (k) eastward wind (m s– ) – , – , – , – , heated cooled latitude (°) , b , a lt it u d e a b o ve b a r (k m ) , , , figure | thermal and dynamical structure of the upper atmosphere predicted by our model. a, temperature structure (colour contours). the dashed line separates regions to the left, which are heated by the polar energy inputs, from regions on the right, which are cooled. at latitudes smaller than those shown the temperature profile remains approximately constant to the equator, exhibiting exospheric temperatures of – k. it is thus clear that the polar energy inputs do not reproduce the observed temperature of , k at u latitude . however, the temperature of , k at the pole is a good match to the infrared spectroscopic temperatures determined in this region . the solid contour represents the fixed lower-boundary temperature of k. the region enclosed by this contour at , – u latitude is thus cooler than the lower-boundary temperature. b, zonal winds (colour contours). the zero contour of zonal wind is shown by the solid line. poleward of , u latitude the winds are almost entirely westward, as expected from the direction of ion drag. the double-lobed structure in the zonal winds is due to structures in the plasma flow model (see the supplementary information). arrows show the combined vertical and meridional circulation. the thinnest arrows represent wind speeds of , m s , the thickness increasing linearly with the logarithm of wind speed until the thickest arrows represent wind speeds of . m s . the cooling effect is produced by two mechanisms. first, the poleward flow induced by ion drag enhances the convective cooling of the low-latitude regions. second, the increase in the poleward wind speed between u and u latitude represents a divergence in the flow that must be balanced by upwelling to satisfy continuity. this upwelling gas expands, and cools adiabatically. it is this effect that produces temperatures cooler than the lower-boundary temperature in this region. divergence upwelling cooling a b curvature not supported downward collapse convergence downwelling heating ‘too prolate’ ‘too oblate’ polew ard collap se equato rward collap se equatorward collapse poleward collapse polew ard collap se poleward collapse subcorotating region lower atmosphere lower atmosphere figure | interpretation of polar dynamics in terms of hydrostatic balance. for the atmosphere to rest in hydrostatic balance, we require internal pressure gradients to perfectly balance the combined gravitational and centrifugal accelerations. for this reason, surfaces of constant pressure normally align themselves with surfaces of constant potential energy: this is the cause of saturn’s considerable oblateness. if the polar upper atmosphere is made to rotate more slowly by ion drag, but in the same gravity field, it must adopt a less-oblate profile if it is to rest in perfect hydrostatic balance. in a, we show the situation that this implies if the atmosphere is isothermal. here the grey shaded region represents the atmosphere lying below the region that we model and the solid lines represent surfaces of constant pressure in the upper atmosphere. in the subcorotating region close to the pole, the less-oblate profile that we require is not supported by the lower atmosphere, and the gas thus ‘collapses’ towards the pole and downwards. this inward flow is strongly convergent, causing downwelling and compression that heats the gas. the steady-state situation is sketched in b. here, the compressional heating at the pole has increased the scale height, allowing a less-oblate profile to be supported. however, owing to the efficiency of vertical thermal conduction, this increased scale height persists at all altitudes. thus, there is a particular pressure surface for which the curvature is ‘just right’ to support the rotation velocity of the gas (thick line). at lower altitudes the curvature is ‘too oblate’ to support the rotation, and the gas continues to collapse inwards and provide compressional heating. at higher altitudes the curvature is ‘too prolate’ and the gas collapses away from the pole. letters nature | vol | january nature © publishing group we must also ask whether we are omitting any important sources of polar energy. the only well-quantified source of polar energy other than those used in our model is energy deposition by the particle precipitation that forms the ultraviolet aurora , . this has already been shown to have a negligible effect on the thermal structure . it has also been suggested that small-scale structures in the ionospheric plasma flow may greatly increase the total joule heating , without a corresponding increase in ion drag. such structures would presum- ably originate in the magnetosphere and solar wind. data collected in these regions by the cassini mission may allow quantification of this small-scale structure and its implications for the flow of energy within the magnetosphere–atmosphere system. however, the good match between our results and the high- latitude temperature measurements suggests that if we were to intro- duce additional polar energy inputs that were sufficient to outweigh the cooling effect and thus resolve the low-latitude energy crisis, we would probably overheat the polar regions. thus our results strongly suggest that low latitudes are heated directly, perhaps by the breaking of buoyancy waves generated in the lower atmosphere – . there may also be some joule heating or particle precipitation at low latitudes that has yet to be accounted for. the cassini mission may contribute to an improved understanding of such processes by providing new measurements of the thermospheric temperature. although a num- ber of low-latitude temperature measurements are at present avail- able, they are neither mutually consistent nor unambiguous , – . a multi-latitude thermospheric data set collected by cassini and ana- lysed self-consistently would thus be an invaluable resource. in summary, our conclusions indicate strongly that polar energy inputs are not the solution to the low-latitude energy crisis at saturn, and that future research should thus focus on direct heating of low latitudes. we expect our results to apply in outline to the slightly more complicated situation at jupiter, and preliminary results from a jovian version of our model support this prediction. however, we are not yet in a position to assess whether our cooling effect may be relevant to the energy crises at uranus and neptune, given the appar- ent complexity of their magnetospheres, but this study does indicate that magnetosphere–atmosphere coupling at these planets is likely to be complicated and may throw up further surprises. received july; accepted december . . atreya, s. k. atmosphere and ionospheres of the outer planets and their satellites ch. (springer, heidelberg, ). . yelle, r. v. & miller, s. in jupiter: planet, satellites and magnetosphere (eds bagenal, f., mckinnon, w. & dowling, t.) – (cambridge univ. press, cambridge, uk, ). . strobel, d. f. & smith, g. r. on the temperature of the jovian thermosphere. j. atmos. sci. , – ( ). . mueller-wodarg, i. c. f., mendillo, m., yelle, r. v. & aylward, a. d. a global circulation model of saturn’s thermosphere. icarus , – ( ). . melin, h. comparative aeronomy of the upper atmospheres of the giant planets. phd thesis, univ. london ( ). . smith, g. r. et al. saturn’s upper atmosphere from the voyager euv solar and stellar occultations. j. geophys. res. , – ( ). . smith, c. g. a., miller, s. & aylward, a. d. magnetospheric energy inputs into the upper atmospheres of the giant planets. ann. geophys. , – ( ). . smith, c. g. a., aylward, a. d., miller, s. & mueller-wodarg, i. c. f. polar heating in saturn’s thermosphere. ann. geophys. , – ( ). . cowley, s. w. h., bunce, e. j. & o’rourke, j. m. a simple quantitative model of plasma flows and currents in saturn’s polar ionosphere. j. geophys. res. a , – ( ). . fuller-rowell, t. j. et al. in step handbook of ionospheric models – (scostep, logan, utah, ). . moses, j. i. et al. photochemistry of saturn’s atmosphere. i. hydrocarbon chemistry and comparisons with iso observations. icarus , – ( ). . atreya, s. k. eddy mixing coefficient on saturn. planet. space sci. , – ( ). . davis, l. j. & smith, e. j. a model of saturn’s magnetic field based on all available data. j. geophys. res. , – ( ). . moore, l. e., mendillo, m., mueller-wodarg, i. c. f. & murr, d. l. modeling of global variations and ring shadowing in saturn’s ionosphere. icarus , – ( ). . richardson, j. d. thermal ions and saturn—plasma parameters and implications. j. geophys. res. , – ( ). . stallard, t. s., miller, s., trafton, l. m., geballe, t. r. & joseph, r. d. ion winds in saturn’s southern auroral/polar region. icarus , – ( ). . clarke, j. t. et al. morphological differences between saturn’s ultraviolet aurorae and those of earth and jupiter. nature , – ( ). . codrescu, m. v., fuller-rowell, t. j. & foster, j. c. on the importance of e-field variability for joule heating in the high-latitude thermosphere. geophys. res. lett. , – ( ). . young, l. a., yelle, r. v., young, r., seiff, a. & kirk, d. b. gravity waves in jupiter’s thermosphere. science , – ( ). . matcheva, k. i. & strobel, d. f. heating of jupiter’s thermosphere by dissipation of gravity waves due to molecular viscosity and heat conduction. icarus , – ( ). . hickey, m. p., walterscheid, r. l. & schubert, g. gravity wave heating and cooling in jupiter’s thermosphere. icarus , – ( ). . hickey, m. p., schubert, g. & walterscheid, r. l. gravity wave heating and cooling in saturn’s thermosphere. eos (suppl. ), abstr. sa a– ( ). . festou, m. c. & atreya, s. k. voyager ultraviolet stellar occultation measurements of the composition and thermal profiles of the saturnian upper atmosphere. geophys. res. lett. , – ( ). . atreya, s. k., waite, j. h., donahue, t. m., nagy, a. f. & mcconnell, j. c. in saturn (eds gehrels, t. & matthews, m. s.) – (univ. arizona press, tucson, arizona, ). . smith, g. r. & hunten, d. m. study of planetary atmospheres by absorptive occultations. rev. geophys. , – ( ). supplementary information is linked to the online version of the paper at www.nature.com/nature. acknowledgements the simulations described in this study were performed using the hiperspace facility at ucl, funded by the uk particle physics and astronomy research council (pparc). c.g.a.s. acknowledges receipt of a case studentship funded by pparc and sun microsystems ltd. author contributions the thermosphere modelling was carried out by c.g.a.s., a.d.a., g.h.m. and s.m. l.e.m. provided the ionosphere model. author information reprints and permissions information is available at www.nature.com/reprints. the authors declare no competing financial interests. correspondence and requests for materials should be addressed to a.d.a. 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, issn - © idosi publications, doi: . /idosi.mejsr. . . . corresponding author: r. sitharthan, department of electrical and electronics engineering, thiagarajar college of engineering, madurai, india. wind energy utilization in india: a review r. sitharthan and m. geethanjali department of electrical and electronics engineering, thiagarajar college of engineering, madurai, india abstract: the enormous population and economic development, made a massive demand for the electrical power in india. in the past decade, the majority of power generated was based essentially on fossil fuel. as india has infinite renewable energy resources there occurs a remarkable change, of shifting the power production from conventional power recourses methods to the non-conventional renewable energy recourses methods. among the renewable energy recourses, wind energy plays a vital role in power generation. even though wind energy has not been well utilised in india, it has made a significant progress in wind energy utilisation for power generation. consequently, the prime objective of this study is to tackle some scenarios of investigation on wind energy utilisation for power production in india. the investigation includes major achievements, future aspects government initiatives and policy on wind energy utilisation. the investigation indicates that india is appreciably in advance in wind energy utilisation. besides, the main problem that faces is the lack of obvious policies on wind energy utilisation and the government initiatives. however, ministry of non-conventional energy sources (mnes) has been formed for the development of wind energy and other renewable resources. the immense development can only be seen in the future decades. key words: renewable energy wind energy wind energy utilisation wind policy introduction energy and solar plant plays a vital role of producing energy crisis is the vital problem that the world faces environmental impacts than the conventional energy in present decade. it is due to enormous growth of resources. furthermore, according to the survey from population and economy development. by analysing the international energy agency, as india is obviously a past decade, the surplus energy crisis have been satisfied developing country it consumes more than percent by by burning coal, hydrocarbons-oil and natural gas leading the year appropriately from the world’s total energy to the carbon emissions that forms environmental crisis. production [ ]. hence, there must be an alternate energy the major environmental crisis such as global warming resources installed in india. and irregular weather patterns affects the earth india is consecrated with lots of alternate renewable environment as well as raises the price of fossil fuel. as energy resources such as solar, wind, tidal, hydro and the prices of coal and oil, concerns the hidden cost about biomass. in india the utilization of wind energy is almost climate change and climate barriers. therefore, in order to higher that other renewable energy resources as the wind solve environmental crisis and energy crisis a new sort of flow in all season throughout the year. in wind energy energy resources was required. hence, renewable energy utilization, india stands in the fifth place among the utilizer resources into existence in the later part of the present in the world. it stands after china, u.s.a, germany and decade [ ]. the renewable energy resource uses the spain in generation of wind power. the significance of energy present in the environment to produce power and renewable energy was predictable in the early s. later which in-turn reduces the impact of environmental crises. on, new wind turbine technologies are developing on the other hand, renewable energies in general (wind, gradually and making a remarkable change than many solar, hydro, tidal, geothermal, biomass. etc) are other countries. furthermore, they have capacity to commonly utilized to produce power. among them, wind generate . gw in present decade and over - gw power. furthermore, they produce considerably lesser middle-east j. sci. res., ( ): - , of new generation capacity is to be installed by [ - ]. risen by . % within last six months and with . % on successively, it reduces carbon di-oxide emission of an the yearly basis (from june- compared with june- average of million tons by . that in-turn reduces ). from the comparative investigation, the annual the irregular weather patterns in india. in addition to that, utilization capacity rate in was at . % and has survey is made on government policy. the indian raised . % by mid- . the five traditional wind energy government policy structure on wind energy utilization utilization countries: china, usa, germany, spain and is particularly investor-friendly, has an attractive tariff india in cooperation contribute’s a % share of the total plans and their rigid government provide a strong wind power production from table . the china foundation for the growth of the wind energy sector. the contributes a total wind capacity of gw in mid- mnre has introduced “generation-based incentive” and unquestionably it would have crossed gw at scheme. as per the scheme, investors will receive present. the us market, after its effectual subside in , incentive of paise per kw/hr of electricity generated has exposed its significant recovery, through a power of by wind projects registered under the scheme. the mw, somewhat greater than canada ( mw) and incentive will, however, stop once the payout reaches australia ( mw). consequently, germany made a rs. crore per mw of capacity. this incentive of rs. strong performance by adding . gw within the first half crore can be drawn in not fewer than four years and not of . this is comparatively lesser than its installation more than years. this decision to incentivize, have in past decade [ ]. furthermore, spanish market has increased the foreign and domestic investors. therefore, contributed only . mw in the first half of . this hopefully india have planned to raise its wind energy could possibly slow-down the spain market in the up- utilization in future decades by catalyze additional coming years. india reserved its position as second investments. largest in asia and fifth largest in the worldwide. india worldwide status of wind energy: wind energy is the additionally, united kingdom and the brazil had made a only major source to fulfil the world’s total electricity brawny performance of adding mw and . gw first demand. wind is plenty in nature, widely spread and low half of . production cost; it can be readily used without any the top ten wind countries are show in table as per process. according to the annual report by the global the utilization capacity installed still mid- . based on wind energy council in the end of december - , wind the efficient usage and higher performance analysis, five power utilizer have emerged over the past decade. the countries china, usa, germany, france and canada has world’s annual wind energy utilization capacity performed stronger than in . based on the inefficient quadrupled in to and the energy utilization usage and slightly lower performance analysis, five capacity doubles all two years. furthermore, the countries india, denmark, italy, spain and uk saw a worldwide wind energy utilization has reached . decreasing market. portugal has dropped out and gw at the end of mid- [ ]. this raise is a appreciably denmark has entered the top list by installing . gw higher when compared to and and wind power higher than the portugal. the rest of the world produces production was around % of total worldwide electricity . gw and the total wind capacity is about . demand. the global wind energy utilization capacity has gw by mid- . added . gw of new wind capacity till the mid- . table : top cumulative installed capacity –june (c-wet) position country total capacity till june- (gw) total capacity end (gw) total capacity end (gw) china . . . usa . . . germany . . . spain . . . india . . . united kingdom . . . france . . . italy . . . canada . . . denmark . . . rest of the world . . . total . . . middle-east j. sci. res., ( ): - , table : wind energy potential in india wind potential total capacity till state in (mw) june - (gw) tamil nadu , . gujarat , . maharashtra , . rajasthan , . karnataka , . andhra pradesh , . madhya pradesh . kerala . others , . total , . wind energy potential in india: in india, wind energy holds the major portion of . % (of . gw total renewable energy capacity) among renewable and continued as the largest supplier of clean energy. the wind potential in india was first estimated by centre for wind energy technology (c-wet) at m hub-height i.e. gw but according to the new survey at m hub height, the potential grows as much as gw. this stature was adopted by the government as the official estimate. however, lawrence berkley national laboratory (lbnl) has stated the potential is over to gw from a survey taken from country-wide network of wind monitoring and wind mapping stations in indian states [ ]. the estimation shows that india’s total wind potential is mw, with tamil nadu, gujarat, karnataka and maharashtra as the leading states up to mid- . this effort of estimation made possible to measure the national wind potential and identified the proper location for harnessing wind power for commercial utilize. by means, they have identified suitable sites with high wind potential. table shows the installation capacity till june- along with wind energy potential in india. wind energy programme in india: the wind energy programme in india begins at the end of . at the beginning, energy programme was adopted based on business-oriented policy, which lead to the triumphant business development by implementing advanced technology. later in , national programme for wind energy development was formed. the national programme embraces wind potential estimation activities; research and technical development; making alertness and opening new wind energy sites; motivating utilities and industry to contribute; expanding the structural capacity of manufacturers, processing, setting and maintenance support for wind generator set-up; and wind policy support. the programme aims at catalyzing commercialization of alternative renewable energy generation within the country. the wind resources assessment programme is being enforced through the state nodal agencies, field analysis unit of indian institute of tropical meteorology (iitm-fru) and center for wind energy technology (c- wet). wind in india are manipulated with the robust south-west summer monsoon, that begins in the month of may-june, when cool, wet air moves towards the land and also the weaker north-east winter monsoon, that begins during the month of october, when cool, dry air moves towards the ocean. the wind flow is strong all over the indian isthmus, except eastern costal isthmus during the month of march to august. furthermore, wind flow is weak all over indian isthmus except the tamilnadu coastline during the month of november to march [ , ]. outstanding feature taken place in the indian programme is wind power investors have shown their interest in planting commercial wind power plant all over the india. the wind power installed capacity is . gw as per the estimation in indian atlas taken by (c-wet) still mid of . the wind potential is calculated at meter hub level of the wind turbine with respect to % land allocated to wind plant. moreover, at present the indian market is installed with larger wind turbines at - meter hub level. such development in hub level and technology made the wind potential higher value with the same land availability than that obtained with the meter hub level with same land availability. the total commercial project installed till mid- is estimated about . mw [ - ]. wind energy status in india: india’s rapidly growing economy and population leads to relentlessly increasing electricity demand. the iea predicts that by , gw of power generation capacity will be needed, which would simply an addition of gw per year. this urgent need is reflected in the target the indian government has set in its th five year plan ( – ), which envisages an addition of . gw in this period, . gw of which is coal. wind energy program was commenced in india by the end of the five yearly plan during - and inth the last few years it has increased considerably. the main objective of the program was the commercialization of wind energy production, support research and development, provide help to wind projects and to create awareness among people. under this program ministry of non renewable energy (mnre) has done various modification regarding incentives, schemes and policies for wind energy. india is relatively new comer to the wind energy sector as compared to denmark or usa. middle-east j. sci. res., ( ): - , table : india’s largest wind power facilities ( mw and greater) (c-wet) total capacity (mwe) ------------------------------------------------------ power plant owner location city state vankusawade wind park suzlon energy ltd. satara dist. maharashtra cape comorim aban lloyd chiles offshore ltd. kanyakumari tamilnadu kayathar subhash subhash ltd. kayathar tamilnadu ramakkalmedu subhash ltd. ramakkalmedu kerala muppandal wind muppandal wind farm muppandal tamilnadu gujdimangalam gujdimangalam wind farm gujdimangalam tamilnadu puthlur rci wescare (india) ltd. puthlur andhra pradesh lamda danida danida india ltd. lamda gujarat chennai mohan mohan breweries and distilleries ltd chennai tamilnadu jamgudrani mp mp windfarms ltd. dewas madhya pradesh jogmatti bses bses ltd. chitradurga dist. karnataka perungudi newam newam power company ltd. perungudi tamilnadu kethanur wind farm kethanur wind farm kethanur tamilnadu hyderabad apsrtc andhra pradesh state rapid transit corp. hyderabad andhra pradesh muppandal madras madras cements ltd. muppandal tamilnadu poolavadi chettinad chettinad cement corp. ltd. poolavadi tamilnadu fig. : total installed capacity india till- june but indian policy support for wind energy has led india india’s cumulative installed capacity up to mid- is and it ranked fifth with largest installed wind power shown in figure . a rapid growth in wind power capacity. the total installed power capacity was , installation has been measured in southern and western mw till july, . now india is just behind usa, china, states in india. a need for about - gw of total germany and spain [ ]. global installed wind power energy generation capacity was reported by the central capacity shows india’s better performance in wind energy electricity authority in its national electricity plan, by the sector shown in table . the five main wind power year . only onshore wind potential has been utilised countries are china, usa, germany, spain and india and so far by india. in spite of the fact that india has long they together represent a share of percent of the global coast line over km, we have not yet tapped our wind energy capacity. offshore wind resource for energy generation. the as per mnre, wind power accounts for the largest capacity utilization factor (cuf) of offshore wind share of renewable power installed capacity i.e. percent turbines is much higher as compared to the onshore ( ), as compared to the other renewable sources. the turbines because of the high offshore wind speed. total installed wind power capacity in india had reached offshore wind steering committee was established by . gw in july [ ]. the total capacity added during mnre in august , which released a draft of the financial year - mid- was around , mw. national offshore wind energy policy in may [ ]. middle-east j. sci. res., ( ): - , steady market growth for wind in india: india is procuring % of its power from renewable energy emerging as a major wind turbine-manufacturing hub sources. current policy and regulatory incentives for wind today due to favourable policy framework, low manpower power development are listed as follows. cost, raw material availability and vast market potential. generation based incentive: initially implemented in currently existing manufacturers have a consolidated june and then re-launched in december by the annual production capacity of over , mw. some of union government for grid connected wind power the international companies with subsidiaries in india are projects. a gbi of inr . per kwh (~ us cent), with a sourcing over % of their components from indian cap of approximately $ , per mw per year, totalling component manufacturers. besides manufactures like $ , per mw over years of a project’s life was enercon, rrb, suzlon and leitmer shriram, win wind has offered under this scheme [ ]. the gbi scheme includes also set up a blade manufacturing facility in india [ , ]. captive wind power projects, but excludes third party sale. the indian manufacturers have ramped up their the scheme is applicable for the projects commissioned production capacity over a period of time. besides on/after . . . eligibility criterion is that projects meeting the domestic demand, some manufacturers have should not avail accelerated depreciation and should sell also started exporting turbines. the wind turbine the electricity to grid at a tariff fixed by serc/state govt. manufactured in india has been exported to countries like the scheme is modified and likely to be announced by thailand, turkey, estonia, netherlands, the uk and mnre. srilanka. according to estimates by wise the annual wind turbine manufacturing capacity is likely to cross , conclusion mw by the end of if all manufacturers go ahead with their plans. india’s growing energy demand requires efficient indian wind energy policy: in , when the mnes the country is going to change. there is no doubt that issued guidelines for purchase of power from renewable renewable sources of energy would play critical role in energy sources by state utilities, it marked the beginning ensuring energy security of the country. there is of initial policy support for renewable energy based power enormous potential to generate energy from renewable generation in india [ ]. the most important development sources like solar and wind. the government of india has after this was the enactment of the electricity act, been very actively involved in promoting renewable with specific provision for promotion of renewable energy. it has been observed that the size of wind turbine energy. however, the ea changed the legal and has increased and the cost of production has decreased. regulatory framework for the renewable energy sector in the future challenge is to bring down the cost further and india. the significant provision of this act are section make it more competitive. the wind turbine cost (h) which give power to state electricity regulatory contributes – % total cost. hence, it is important to commission for fixing prudential tariff for renewable design, develop and market newer, technologically energy projects so as to promote investment while superior and more cost efficient wind turbines to reduce section ( ) enables state commissions to create market unit cost of wind power. it is high time for the government for re and co-generation projects by prescribing a to develop a comprehensive renewable energy policy and minimum percentage of electricity to be procured from non design support schemes to send across positive signals conventional energy sources [ - ]. to the wind power producers. these producers should be regulatory and policy incentives for wind power: encouraged to invest in wind energy. no doubt, india has india, as part of its obligations to the united nations marked its presence all over the world in generation of climate convention (unfccc), released a national action wind energy. it has huge potential for producing wind plan on climate change (napcc) in june [ ] that energy too, but there are still some lacunas. indian laid out the government’s vision for a sustainable and government has laid the foundation for a broad-based clean energy future. the napcc stipulates that a renewable energy program and designed it specially to dynamic minimum renewable purchase target of % (of meet the growing energy needs and to fulfil energy total grid purchase) may be prescribed in - and shortage. despite all its efforts, india is unsettled by this should increase by % each year for a period of china and has now slipped to the fifth rank in its years [ ]. that would mean that by , india should be contribution to global wind energy production. energy management. in the coming years energy mix of middle-east j. sci. res., ( ): - , analysis shows that the main factor behind china’s lead . chen, t.c. and j.m. chen, . the - -day mode is presence of a countywide renewable energy law. it may of the indian monsoon: its relation with the time be concluded that india will have to improve in order to variation of monsoon rainfall, monthly weather compete with china and become the leader in wind energy review, : - . generation. . gutzler, d.s. and d.e. harrison, . the structure references near-equatorial eastern indian and western pacific . sharma, a., j. srivastava, s.k. kar and a. kumar, . http://www.inwea.org/others/msme .pdf. . wind energy status in india: a short review. . http://www.inwea.org/publications.htm.htm. renewable and sustainable energy reviews, . http://www.cwet.tn.nic.in/html/information_gi.html : - . [accessed . . ]. . sahu, b.k., m. hiloidhari and d.c. baruah, . . http://www.cwet.tn.nic.in/docu/information_for_s global trend in wind power with special focus on the na.pdf. top five wind power producing countries. renewable . http://www.cwet.tn.nic.in/docu/tariff_serc_ _ and sustainable energy reviews, : - . _ .pdf [accessed . . ]. . http://www.gwec.net/fileadmin/documents/publicat . www.recregistryindia.in [accessed . . ]. ions/gwec prstats - - final.pdf. . www.isgtf.in [accessed . . ]. . http://mnre.gov.in/filemanager/userfiles/presentati . http://pmindia.gov.in/climate_change.php. ons-nwm- /gomathinaygam.pdf [accessed . source: centre for budget and governance . . ]. accountability report on framework and . http://www.wwindea.org/webimages/wwea_half performance of national clean energy fund, _year_report_ .pdf. july . . www.indianwindpower.com/investment_by_welsp . based on inr-usd exchange rates in october un_energy.html. draft of “the national offshore wind energy policy” . http://www.mnre.gov.in/filemanager/advertisement/ may, accessed at http://bit.ly/ vlu e ( ). eoi-energy-storage-demonstration-project-for- . www.cbgaindia.org. supporting-renewable-generation-link.pdf [accessed . . ]. and evolution of seasonal wind anomalies over the oceans. monthly weather review, : - . page - © mat journals . all rights reserved journal of mechanical robotics volume issue nuclear fusion reactor- a review nidarsh prajay, bharath m n student, assistant professor department of mechanical engineering jss science & technology university, mysore, karnataka, india email: nidarshprajay@gmail.com, bmnsjce@gmail.com abstract nuclear fusion reaction what actually happens in it , the history of nuclear fusion reactors, contrasting nuclear fusion reactor power with other currently available energy resources, the advantages of using nuclear fusion reactors to generate energy, what is a “tokamak” and how a tokamak works, conclusion and referred articles. keywords: fusion, plasma, nuclei, stellarator, tokamak, torus introduction reactions in which two or more atomic nuclei come close enough so that the nuclear force pulling them together is greater than the electrostatic repulsive force between them is called nuclear fusion. here the nuclei combine to form a heavier nucleus which is exothermic if nuclei combining is lighter than iron , otherwise it is endothermic the nuclear force acts only for short distances but the electrostatic repulsive force acts for longer distances. in order for fusion reaction to take place, the participating nuclei need to be given enough kinetic energy to overcome repulsive force and come close enough for nuclear force to be effective. the ways to achieve this are by either accelerating nuclei using a particle accelerator or by heating atoms to a sufficient temperature so as to strip them of their electrons, leaving behind just the bare nucleus (ion) in form of plasma. because the charges here are separated, plasma are electrically conducive and magnetically controllable .since plasma can be easily controlled, many fusion devices use the latter method of heating atoms to high temperature to form plasma as basis for fusion reaction fusion reaction does take place in the sun where hydrogen nuclei combine to form helium nuclei. one important point to be gathered here is that while high temperature and pressure as found inside the sun is not a theoretical prerequisite for nuclear fusion(as accelerating a particle can also be done),it is nevertheless the most commonly used method for nuclear fusion reactions as it is more viable than accelerating particles nuclear fusion reactor- history the field of fusion reactor research started from the late s.r atkinson and f.g houtermans suggested that star‟s energy source is due to some sort of a nuclear reaction taking place inside the star. quantitative evaluation of nuclear fusion was first revealed in the late s, thus spiking interest in the field as nuclear fusion reactor was promised to be the ultimate solution for energy crisis. in l spitzer,a reputed astronomical scientist came up with the idea of a “stellarator”,a device which confines hot plasma by applying a magnetic field twisted so as to contain the plasma. currently “tokamak”,a type of plasma confinment system, which twists magnetic field by producing current inside of plasma has become a main trend in fusion research and development, which page - © mat journals . all rights reserved journal of mechanical robotics volume issue has continued till now. as time passes by over the decades with both research in the field and improvement in technology, the plasma confinement and its temperature have been improving. currently the iter project, which is the world‟s largest fusion project, is now in progress. iter (international thermonuclear experimental reactor) is an international collaboration on research of nuclear fusion and its engineering applications which is funded and run by member entities-the european union, india, china, russia, japan, the united states and south korea. iter is an experimental tokamak nuclear fusion reactor being built in the south of france literature survey t. hamacher et al ( ) have concluded that fusion reactor research has matured over the last decades, with the joint european experiment jet already having produced more than mw of fusion power at a q value of . and that technology for the next step in form of iter have already been improved in construction of prototypes and by intense r&d in engineering. fusion if ever made commercially viable, would fit into a sustainable energy system and be able to supply clean energy for millennia at economically acceptable costs. yoneda et al ( ) have concluded that towards iter project and by default nuclear fusion reactor technology in general, the r&d activities have been extensively conducted by iter members. since nuclear fusion reactor is not yet commercialized, official government intervention is required to support the development of this technology.it can also be said that r&d activities and development in nuclear fusion reactors greatly depends on progress in large device experiments. the design trend and analysis show that tokamak has become the preferred method and in commercialization, compactness of reactor has been gathering attention .overall there has been steady progress in international r&d towards fusion power plants. ankit gupta et al ( ) have concluded that the process of nuclear fusion for power generation is applicable on a large scale. nuclear fusion power generation is clean in the sense that it does not produce any greenhouse effect or other eco-harmful effects which are normally associated with fossil fuels. in a nuclear fusion reactor (once physically realized),the reactor can convert nearly percent of energy generated into electrical energy as compared to percent in the case of a traditional coal fired plant(this is due to greater efficiency of the conversion process of energy liberated into electrical energy, in case of fusion reactor). the fusion reactor would cost half as much as a traditional coal power plant to run annually since the fuel used here is extremely cheap and readily available. moreover as there is no radioactivity here, extreme safety measures are unnecessary. as the amount of fuel in the nuclear fusion reactor at any given time is very small, nuclear fusion reactors are also very safe to use. the irsn institute ( ) have concluded that those who are designing nuclear fusion reactors should focus on these subjects as a priority- a. residual heat removal, considering the tokamak cooling systems and those for blanket sectors. b. identification of the preferred waste management and containment system based on the general policy of the country which is hosting the nuclear fusion reactor c. possibilities of minimizing and limiting the overall quantity of tritium present in the facility and also page - © mat journals . all rights reserved journal of mechanical robotics volume issue considering the usage of tritium breeding blankets s. chiocchio et al ( ) have concluded by saying that the iter project is the current pinnacle of technology of nuclear fusion reactor design and engineering and is also the culmination of years of research in fusion and has currently finally entered into the building and construction phase of the project. the management and proper coordination of a project of this vast magnitude, with unprecedented new technology and r&d is itself a complex challenge, but the sharing of a common goal towards achievement of commercialization of fusion reactor among the member countries, with personal commitment among the constituent individuals will focus the iter ethos and keep the whole team highly motivated and efficient and will be the key to achieving success in this project. shutaro takeda et al ( ) have concluded by saying that even though nuclear fusion energy has faced widespread criticism and a quip of it always being years ahead (due to fusion scientists since the s continuously predicting commercialization of fusion reactor to take years), it appears that this time it will be true and a commercial, working fusion reactor can indeed be achieved in the next decades. current plans to realize a commercially viable fusion power plant are being continuously updated but they should still be treated with caution as they are subjected to uncertainties, unknown barriers to technological progression and limitation of resources. at the current timeframe, it can be said that a commercial fusion reactor can be achieved in the next decades. every effort to realize this timescale ( and to possibly advance it) should be done so that fusion can fulfil its vast potential and make a much needed difference in the field of global energy. silvano tosti et al ( ) have concluded that successful exploitation of nuclear fusion via magnetic confined devices such as tokamak relies on the development of a reliable and efficient fuel cycle. in tokamaks of the future, tritium will be produced in a lithium based breeding blanket, hence to sustain fusion reaction with deuterium it has to be extracted and purified before being sent to plasma chamber. finally, an innovative membrane gas liquid contactor (mglc) has been researched for extraction of tritium from liquid lipb, proposed for future tokamaks as a candidate blanket material a.cardinali et al have concluded that there is a undoubted need of actively shaping the current profile at large radii of plasma column so as to exploit the self-produced current and thus save the huge costs of the heating systems. the natural profiles usually produced by the plasma are usually matched by lower hybrid current drive, which is successfully extrapolated to higher densities and currently, with larger flexibility to higher temperatures envisaged for a fusion nuclear reactor, thus enabling its economic viability and prospects for commercialization. nuclear fusion reactor- contrast with other energy sources and its advantages for any country and its development the e formula-energy security, environmental protection and economic efficiency and sustainable economic growth is paramount. for this the country needs access to precious energy resources, vital for development in nearly all sectors of the economy, however many countries today either do lack access to the level of energy resources needed for sustained growth, especially as the population keeps on increasing, adding more strain on the economy of certain countries like india and china. page - © mat journals . all rights reserved journal of mechanical robotics volume issue huge consumption of energy resources in the world today has led to depleting energy reserves of fossil fuels like coal and petroleum. thus development in many countries gets retarded due to lack of energy resources. in addition to this while fossil fuels do offer constant energy, they do cause severe environmental problems such as toxic and noxious smoke, drastic degradation in air and water quality and respiratory diseases. renewable energy resources, although unlimited in nature do have their own drawbacks of varying supply of energy which is not uniform. in addition to this, some renewable energy sources such as solar can only be used during certain time limits such as in daylight nuclear fission reactors have unlimited supply of energy and have continuous availability of power but do produce a lot of highly toxic radioactive waste, which proves difficult to dispose. in addition, they must be constantly monitored, so as to prevent reactor meltdown, which can cause dangerous consequences as in the example of chernobyl. in short a unstable nuclear fission reactor is an atomic bomb. nuclear fusion reactors like their fission reactor counterparts do have unlimited and continuous supply of energy but unlike their fission counterparts do not produce highly radioactive wastes. in addition to this they can produce more net energy than any other energy source. also unlike in case of a nuclear fission reactor, in fusion reactor if the reaction were to spiral out of control, the reaction would stop and would not produce a meltdown comparable with those seen in fission reactors. thus the advantages of nuclear fusion reactor over other energy sources are  fusion reaction generates the most energy possible in any power plant, generating up to million times the energy in any chemical reaction.  fusion reactors are clean and do not cause emission of any greenhouse gases, thus not leading to global warming  fuel required for fusion reactors are widely available and are nearly inexhaustible. deuterium can be distilled from nearly all forms of water, including seawater  there is no creation of any radioactive waste in the entire process, and thus the problem of radioactive waste management and radioactive emission is eliminated.  since no enriched radioactive fuel is used here, there is limited list of proliferation  unlike a traditional nuclear fission reactor, in a fusion reactor if there is any disturbance in the reaction the plasma cools immediately and the reaction stops. here there is no risk of a chain reaction and thus there is no risk of a meltdown of the reactor working and design of a nuclear fusion reactor in tokamak form for any fusion reaction to take place in a laboratory, three necessary conditions are required-  very high temperature- to excite nuclei and cause high energy collisions,  sufficient plasma density- to increase the probability of having collisions  sufficient confinement time- to confine the plasma which has a tendency to expand, within a given volume the tokamak is an experimental device in the form of a torus designed to harness the power of nuclear fusion reaction, most commonly the fusion of deuterium or tritium isotope to form helium nuclei. the advantages of tokamak over other fusion reactor designs is that the tokamak can currently produce the world‟s highest page - © mat journals . all rights reserved journal of mechanical robotics volume issue plasma temperature, plasma densities and confinement durations of any confinement device in the case of a tokamak, there are two superimposed magnetic fields which enclose the plasma and there is an toroidal field generated by external coils on the one hand and field of flow of the plasma in the other hand. thus when the magnetic fields are combined, the field lines run helicoidally around the torus center. thus the necessary twisting of field lines and structure of magnetic areas is done. apart from these fields, the tokamak requires a third vertical field (poloidal field), which is used for fixing the position of flow in the plasma container. the flow in the plasma is mainly used to create the enclosing magnetic field, in addition to which it also provides effective initial heating of the plasma. a transformer coil is normally used to induce flow in the plasma. owing to the transformer the tokamak does not run continuously but in pulses. however, since a power plant cannot be run in pulses for technical reasons, methods are being evaluated to run the fusion reactor in continuous flow- for example by high frequency waves. in the tokamak the actual energy is got by creation of a large amount of high energy neutrons from plasma. since these neutrons are not charged, they are no longer held in the plasma stream by the magnetic fields and thus not being confined, move on until they collide with the inner walls of the fusion reactor. the heat from these neutrons in converted into energy by generating steam and running turbines and generators, however a lot of energy is lost in the process due to cooling. to protect the fusion reactor from breakdown due to excessive heat ,a complex cryogenic cooling system consisting of a mixture liquid helium and liquid hydrogen combined with ceramic plates are required to protect the superconductors and reactor walls. some additional sources of heating the plasma to the required temperature are  neutral beam injector  radiofrequency heating conclusion nuclear fusion reactor is still a work in progress. the technology of effectively containing the plasma and maintaining high plasma temperatures and densities is not yet satisfactorily developed as well as the cryogenic cooling processes. however as the technology required for these develops, both the ease and the cost of building the fusion reactor would come down, which given its vast potential, means that this option soon becomes the optimal one. currently the biggest problem in nuclear fusion technology is physically realizing it and making it commercially viable. in jet (joint european torus) was able to set the then world record for fusion output at mw from mw heating input and - mw total input of electric power, a record which still stands to this day. this is also the current world record for the value of q, which was . in this experiment. it can be observed here that even at the maximum value obtained till date for fusion power generation and q value the reactor was unable to break even, that is the reactor still consumed more energy than it generated, resulting in a net negative energy realized or generated form the reactor. this is one of the main drawbacks preventing nuclear fusion reactor technology from being commercialised. given the advantages of the fusion reactor and its unmatched ability to produce energy, it would be prudent to say that it would be the best solution to the energy crisis. nuclear fusion reactor is widely touted to be the ultimate solution to the world‟s energy crisis. page - © mat journals . all rights reserved journal of mechanical robotics volume issue this is because it is clean (no pollution) has no risk of meltdown, produces no toxic radioactive wastes. in addition up to per cent of the energy liberated in a fusion power plant is converted into electricity, compared to % in case of a coal fired plant. this is due to greater efficiency in conversion of fusion energy into electrical energy in fusion reactor, compared to conversion of thermal energy into electrical energy in case of a coal plant. since at any instant, only a small amount of fuel is present in the reactor, the fusion reactor is extremely safe compared to other power plants, and nothing serious might occur even in case of a minor failure in some of its components. in addition since it is not radioactive and extremely safe, unlike fission reactors and coal plants, fusion plants can be located near or even in middle of a city. thus large amounts of wiring required to transmit power ,which adds to cost of utilization of power plant as well as causing large amounts of energy to be lost while transmitting in the form of heat which are essential for fission and coal power plants can altogether be avoided for fusion power plants, thus saving on energy and net cost(since there is minimum power loss) most importantly, fuel required for it can be easily and widely obtained from nearly any water sources such as seawater in abundant quantities. nuclear fusion reactor has an annual running cost nearly half of that of other power plants like coal fired power plants, due to its fuel being extremely cheap and readily available. thus many developing countries with no access to other energy resources can easily obtain precious energy to satisfy their needs through fusion reactors, thus bringing out development in the world. thus nuclear fusion reactors are valuable for sustainable and eco-friendly development of the world. references . t. hamacher and a.m. bradshaw “fusion as a future power source: recent achievements and prospects”- published in the proceedings of the th world energy congress. site- https://fire.pppl.gov/energy_eu_wec . pdf . yoneda, ryota, research and technical trend in nuclear fusion in japan” from interdisciplinary graduate school of engineering sciences, kyushu university site- http://www.tj.kyushuu.ac.jp/evergreen/ contents/eg _ _content/pdf/page s% - .pdf . ankit gupta & rustam sengupta, “analytical study of the development of nuclear fusion reactors as potential source of energy in the future” site- https://pdfs.semanticscholar.org/ d/ fff bf e ed cc c f.pdf . „„nuclear fusion reactor\\safety and radiation protection considerations for demonstration reactors that follow iter facility‟‟, published on november - by irsn (institut de radioprotection et de sûreté nucléaire) irsn report- \ site- https://www.irsn.fr/en/research/publi cationsdocumentation/scientificbooks/ documents/iter- va_web_non_imprimable.pdf . „iter and international scientific collaboration‟ by s. chiocchio, iter jws, published in proceedings of epac . shutaro takeda and richard pearson, „nuclear fusion power plants‟, research gate, november- . . /intechopen. . site- https://www.researchgate.net/publicati page - © mat journals . all rights reserved journal of mechanical robotics volume issue on/ _nuclear_fusion_power _plants . cycle‟ by silvano tosti and alfonso pozio, „membrane processes for nuclear fusion fuel published in research gate october site- https://www.researchgate.net/publicati on/ _membrane_processes_ for_the_nuclear_fusion_fuel_cycle . a. cardinali, c. castaldo, r. cesario, l. amicucci, a. galli, f. napoli, l. panaccione, c. riccardi, f. santini, g. schettini & a. a. tuccillo, „radio- frequency current drives for thermonuclear fusion reactors‟, published on july in scientific reports volume , article number: ( ) site- https://www.nature.com/articles/s - - - . https://www.euronuclear.org/info/ency clopedia/t/tokamak.htm . https://www.iter.org/sci/makingitwork . http://www.ccfe.ac.uk/tokamak.aspx . https://futurism.com/tokamak-reactors . https://www.iter.org/sci/fusion . https://www.iter.org/mach/tokamak wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ rogun dam — path to energy independence or security threat? | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /su corpus id: rogun dam — path to energy independence or security threat? @article{eshchanov rogund, title={rogun dam — path to energy independence or security threat?}, author={bahtiyor r. eshchanov and m. grinwis and sanaatbek k. salaev and ruzumboy a. eshchanov}, journal={agricultural & natural resource economics ejournal}, year={ } } 	bahtiyor r. eshchanov, m. grinwis, + author ruzumboy a. eshchanov 	published 	economics 	agricultural & natural resource economics ejournal the revitalization of the rogun hydropower station project and launch of an initial public offering has led the water-energy disputes between tajikistan and uzbekistan to a new stage. while two riparian states advocate their positions from their own perspective, it gives the impression of being a “prisoners’ dilemma” case from a regional cooperation point. this paper aims to review the decision of project revitalization from the unconventional security perspective, focusing mainly on its impact… expand view on ssrn mdpi.com save to library create alert cite launch research feed share this paper citationshighly influential citations background citations view all paper mentions news article an emerging market for - years down the road seeking alpha december citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency international legal initiatives of uzbekistan in the development of cooperation on transboundary waters in central asian states 	umid murodovich saydakhmedov 	political science 	 	pdf save alert research feed fostering tajik hydraulic development: examining the role of soft power in the case of the rogun dam 	filippo menga, n. mirumachi 	environmental science 	 	 	pdf 	view excerpts, cites background save alert research feed assessment of transboundary river basins for potential hydro-political tensions 	l. d. stefano, j. petersen-perlman, e. sproles, jim eynard, a. wolf 	geography 	 	 	pdf save alert research feed the integrated hydropower sustainability assessment in tajikistan: a case study of rogun hydropower plant 	zhao xu, yumin niu, yangze liang, zhigang li, atoev iftikhor 	business 	 	 	pdf 	view excerpts, cites background save alert research feed et trøblete naboskap: konflikten rundt rogun- demningen i tadsjikistan 	turid austin 	geography 	 save alert research feed how would the rogun dam affect water and energy scarcity in central asia? 	m. bekchanov, c. ringler, anik bhaduri, m. jeuland 	environmental science 	 	 	highly influenced 	pdf 	view excerpts, cites background save alert research feed non-hydropower renewable energy in central asia: assessment of deployment status and analysis of underlying factors 	e. shadrina 	business 	 	 save alert research feed efficient water allocation and water conservation policy modeling in the aral sea basin 	m. bekchanov 	environmental science 	 	 save alert research feed water quality, potential conflicts and solutions—an upstream–downstream analysis of the transnational zarafshan river (tajikistan, uzbekistan) 	m. groll, c. opp, r. kulmatov, m. ikramova, i. normatov 	environmental earth sciences 	 	 	view excerpt, cites background save alert research feed economic costs of reduced irrigation water availability in uzbekistan (central asia) 	m. bekchanov, j. lamers 	economics 	regional environmental change 	 	 save alert research feed ... ... references showing - of references sort byrelevance most influenced papers recency the culture of national security : norms and identity in world politics 	m. finnemore 	 	 	pdf save alert research feed reliving the past in a changed environment: hydropower ambitions, opportunities and constraints in tajikistan 	k. wegerich, o. olsson, j. froebrich 	political science 	 	 	pdf save alert research feed tajikistan: 'revolutionary situation' or a resilient state? 	a. matveeva 	geography 	 	 	pdf save alert research feed central asia's second chance 	m. b. olcott 	political science 	 	 save alert research feed the environment, security and regional cooperation in central asia 	douglas l. tookey 	economics 	 	 save alert research feed is the environment a national security issue? 	marc a. levy 	political science 	 	 	pdf save alert research feed central asia's raging waters the prospects of water conflict in central asia 	william b. hartman 	geography 	 	 	pdf save alert research feed redefining security. 	j. t. mathews 	medicine 	foreign affairs 	 	 save alert research feed the water–energy puzzle in central asia: the tajikistan perspective 	murodbek laldjebaev 	political science 	 	 save alert research feed calculating the benefits of transboundary river basin cooperation: syr darya basin 	r. teasley, d. mckinney 	business 	 	 save alert research feed ... ... related papers 	abstract 	paper mentions 	 citations 	 references 	related papers stay connected with semantic scholar sign up about semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue hvof to superficial protection of industrial valves and rotors tribo-corrosion protection of valves and rotors using cermet layers applied with hvof julio sanchez , miguel angel barbes , roberto gonzalez , luis felipe verdeja . ( ) svf cermetalloy . www.svfcermetalloy .com. ( ) universidad panamericana, faculty of engineering, augusto rodin , , mexico, robglez@up.edu.mx ( ) university of oviedo, e. t. s. de ingenieros de minas, independencia , , spain, www.unioviedo.es/sid-met-mat/ key words: hvof, wear protection, tribo-corrosion, organic processes, abstract the economic viability of equipment in industrial facilities that perform organic processes depends on the capacity of auxiliary equipment, such as valves or rotors, to withstand wear of the tribo-corrosion type (combination of heat and an aqueous medium). the use of surface engineering techniques such as high velocity oxy-fuel (hvof) in order to apply carbide based cermet layers and showing very positive results in decreasing tribological and corrosion mechanisms, is still industrially evaluated against the use of wear resistant bulk materials. a comparison, after a working campaign, between non-protected and hvof treated parts is presented. . introduction the energy crisis that took place in , had major repercussions in all the countries with market economies and resulted in shifts in the technology development strategies in order to achieve a more rational and efficient use of raw materials, improving manufacturing processes and the performance of the materials used in these facilities. the bulk materials used in the design and construction of industrial equipment must withstand wear of both mechanical and chemical (or electro-chemical) types. furthermore, if temperature is high (above °c, which is a temperature limit that restricts the use of water in the liquid state), other oxidation processes are activated (oxidizing atmospheres with   o  p mpa), as well as chemical attack by metallic or metal oxides mixtures in the form of melts. there are many routes in order to solve design problems for parts that present wear mechanisms related to mechanical features: a) increase the thickness of the material b) increase hardness http://www.svfcermetalloy .com/ mailto:robglez@up.edu.mx http://www.unioviedo.es/sid-met-mat/ the use of thicker walls became a common practice until the mentioned energy crisis. current solutions used be most specialized engineering firms, are focused in the modification of materials using new alloying elements and/or heat treatments, resulting in harder materials though losing toughness. nevertheless, an increase in hardness is not always directly related to a better tribological behavior ( ) . wear mechanisms: tribo-corrosion a system suffers mechanical wear when superficial contact with another material takes place: a force is applied and there is considerable displacement between the surfaces. if mechanical conditions or thermal variations are high, the wear may produce failure by fatigue. another mechanism to be considered in the wear of materials in general and metals and their alloys in particular is electrochemical corrosion: water acting as solvent and addition of acid or basic products, along with dissolved oxygen and temperature, will activate the anodic dissolution of the metal. figure presents, from a thermodynamical point of view, the equilibrium of the fe-o-h system at constant (atmospheric) pressure and °c temperature for an iron concentration of - moles·liter - solution, known as the proubaix diagram ( , ). . . . . . - . - . - . - . fe - h o - system at . ºc molaridad del fe: . · - moles/kg h o ph e (volts) fe fe o fe o fe(+ a) fe(+ a) feoh(+a) figure . proubaix diagram at °c for the fe-o-h system (atmospheric pressure). fe + (aq) = - moles·litre - . tribo-corrosion is defined as the combination of mechanical and electrochemical mechanisms producing wear and, consequently, acting simultaneously and aiding each other to produce the wear of the material, this is, the amount of material lost due to mechanical-electrochemical activity is higher than the sum of each of the mechanisms acting separately ( ). consequently, tribo-corrosion is relevant in primary industry processes, and specifically on preparation-grinding-milling of raw materials and mostly evident in finishing stages that use aqueous environment. likewise, digestion-lixiviation processes for pulps (solids in aqueous suspension) using acid, basic or oxidizing solutions also present this type of wear. as an example, food industry extracts sugar from beets using alkaline solutions at ~ °c. in all the previous cases, the simultaneous activity of erosive (perpendicular stress-impact), abrasive (mostly tangent stress-impact) or sliding (combination of tangent and perpendicular stress-impact) mechanisms along with electrochemical corrosion produced by local micro-anodes and cathodes will result in a considerable damage of the equipment, installations and auxiliary elements (stirrers, feeders and valves). two alternatives have been used recently in order to solve this type of wear: a) design of devices with materials highly resistant to electrochemical wear: titanium- or tantalum-based alloys. b) manufacture of parts highly resistant to erosion, abrasion or sliding wear by raising the amount of mn, cr, ni or mo in both carbon or stainless steels. in most cases, the first alternative is economically unviable, turning the second one in the most frequently used practice by design-industrial facilities construction engineering firms. furthermore, this last practice not only raises the mechanical resistance of the material by adding alloying elements but also intrinsically increases resistance to electrochemical corrosion wear. a third alternative to solve tribo-corrosion problems is using a low cost base (bulk) material and adding a surface with the required chemical and mechanical stability. if the characteristics of the protective surface are adequate (different types of wear may or may not be reduced using hvof coatings)( ), the chemical-physical and mechanical characteristics of the base material (which acts as support for the installation) will only demand adequate adherence of this protective layer in order to avoid wear mechanisms. consequently, it would be detrimental if an inadequate application of the protective surface results in longitudinal (delamination of the layers) or vertical cracks which allow contact between the environment(or corrosive fluid) and the base material ( , ). . experimental data protection of the surface using high velocity oxygen fuel – hvof is one of many thermal projection techniques perfected since , for surface engineering processes, in which a suspension of metallic or ceramic powders are placed over the surface of the material to be protected at a speed two or three times higher than sound and ~ °c temperatures ( ) as shown in schematically in figure . the combined effect of speed (high kinetic energy) and temperature results in characteristics of a surface layer that show simultaneously low porosity (less than %) with very good adherence to the substrate (base metal needing protection) ( , ). piping of oil and gas industry in contact with sea water (offshore facilities) is a good example of this ( ). figure . hvof process for cermet coating of surfaces for the sugar industry that uses beets as raw material, protective layers applied with hvof to auxiliary equipment (valves and rotors) allows very long working periods. in this case, a low carbon ferrite-perlite steel, usually required by the construction industry and with . ~ . % mn, is used as a base for ceramic-metal (cermet) layers: cr or w carbides based. table i indicates the elemental analysis of the cr and w based cermets applied with hvof for these equipment ( ). ni. fe and co act as binding metal of the carbide particles in order to form ceramic-metal composites. though very much is known about cermets as tool materials for different applications, the characteristics of these cermet layers from a mechanical and corrosive point of view are very different. moreover, metallic binders (ni) must assure adherence and toughness at the surface, which may also be a function of the geometry of the part ( ). table-i. chemical composition for cr and w based cermets cr cermet % cr . % c . % ni . % fe w cermet % w . %c . % co . % cr + fe after a nine month working campaign, the effect of wear in a rotating auxiliary system is shown in figures and . the material of the part shown in figure is a rotor structure damaged with grooves or tracks over the surface of a hot rolled steel with a ferrite-pearlite structure ( . % c and . % mn). on the other hand, figure presents the surface integrity, at the end of the campaign, of the same steel with a µm layer of cr-w cermet applied with hvof. in both situations, the material was in contact with an alkaline solution formed with different proportions of solids in suspension (siliceous clays) for a nine month period, at a temperature of °c. the surface wear of the part shown in figure is almost non-existent, though at many zones the thickness of the protecting layer has been reduced to ~ µm (starting thickness of µm). figure final state after a working campaign of a rotor in a sugar production facility. figure . final state of a rotor for a sugar production facility after a working campaign and protected with cr and w cermet layers. . conclusions hvof projection technique is a very efficient surface treatment, especially in those cases where auxiliary equipment (rotors, valves or pumps) must be protected from wear in sugar production facilities that use beech. the use of hvof as protective layer is efficient in both a structural and an economic way, as it allows for the same device to be used in periods as long as months, reducing the cost of maintenance stops. parts not protected with hvof layers can suffer damage that will make its further recovery (for example, by applying welded metal layers) impossible. in some cases, not protected parts, such as pumps may suffer perforations during the working campaign, requiring its replacement during extraction activities. the superficial damage in different auxiliary equipment in a sugar production industry will result in energy consumption, loss of productivity due to production stops and, consequently, low economic efficiency. . acknowledgments the authors wish to thank svf cermetalloy firm, at asturias, spain, for access to industrial facilities and data, and also to maria jose quintana for text and figures revision. . references ( ) st. siegmann, o. brandt, n. margadant, tribological requirements of thermally sprayed coatings for wear resistant applications, ist international thermal spray conference . thermal spray: surface engineering via applied research, montreal, canada, ( ) ballester, a.; verdeja, l. f. y sancho, j. p. ( ): metalurgia extractiva: fundamentos, síntesis, madrid, pp. - . ( ) hsc database chemistry. ( ). outokumpu research oy, version . . finland. ( ) vázquez, a.; damborenea, j.j. ( ): “ciencia e ingeniería de las superficies de los materiales metálicos”. ed. consejo superior de investigaciones científicas, csic, colección textos universitarios no. , madrid, pp. - ; - . ( )introduction to thermal spray processing asm international. all rights reserved., handbook of thermal spray technology - ( ) puértolas, j. a.; ríos, r.; castro, m.; casals, j. m. ( ): “tecnología de superficies en materiales”. ed. síntesis, madrid, pp. - . ( )mohammed yunus, j.fazlur rahman, an investigation towards characterization of thermally sprayed industrial coatings, (ijaest) international journal of advanced engineering sciences and technologies vol no. , issue no. , – , ( ) sobolev, v.v.; guilemany, j. m. ; nutting, j.( ): “high velocity oxy-fuel spraying”. maney publishing and institute of metals (iom), london, uk. ( ) erosion - corrosion of cermet coating, magdy m. el rayes, , hany s. abdo, and khalil abdelrazek khalil, int. j. electrochem. sci., ( ) - ( ) verdeja, l. f.; sancho, j. p. y ballester, a ( ): materiales refractarios y cerámicos, síntesis, madrid, pp. - ; - . keep calm and survive: adaptation strategies to energy crisis in fruit trees under root hypoxia plants review keep calm and survive: adaptation strategies to energy crisis in fruit trees under root hypoxia ariel salvatierra , guillermo toro , patricio mateluna , ismael opazo , mauricio ortiz and paula pimentel ,* plant genomics laboratory, centro de estudios avanzados en fruticultura (ceaf), rengo , chile; asalvatierra@ceaf.cl plant stress physiology laboratory, centro de estudios avanzados en fruticultura (ceaf), rengo , chile; gtoro@ceaf.cl (g.t.); pmateluna@ceaf.cl (p.m.) plant breeding laboratory, centro de estudios avanzados en fruticultura (ceaf), rengo , chile; iopazo@ceaf.cl agronomy laboratory, centro de estudios avanzados en fruticultura (ceaf), rengo , chile; mortiz@ceaf.cl * correspondence: ppimentel@ceaf.cl; tel.: + - - received: july ; accepted: august ; published: august ���������� ������� abstract: plants are permanently facing challenges imposed by the environment which, in the context of the current scenario of global climate change, implies a constant process of adaptation to survive and even, in the case of crops, at least maintain yield. o deficiency at the rhizosphere level, i.e., root hypoxia, is one of the factors with the greatest impact at whole-plant level. at cellular level, this o deficiency provokes a disturbance in the energy metabolism which has notable consequences on the yield of plant crops. in this sense, although several physiological studies describe processes involved in plant adaptation to root hypoxia in woody fruit trees, with emphasis on the negative impacts on photosynthetic rate, there are very few studies that include -omics strategies for specifically understanding these processes in the roots of such species. through a de novo assembly approach, a comparative transcriptome study of waterlogged prunus spp. genotypes contrasting in their tolerance to root hypoxia was revisited in order to gain a deeper insight into the reconfiguration of pivotal pathways involved in energy metabolism. this re-analysis describes the classically altered pathways seen in the roots of woody fruit trees under hypoxia, but also routes that link them to pathways involved with nitrogen assimilation and the maintenance of cytoplasmic ph and glycolytic flow. in addition, the effects of root hypoxia on the transcription of genes related to the mitochondrial oxidative phosphorylation system, responsible for providing adenosine triphosphate (atp) to the cell, are discussed in terms of their roles in the energy balance, reactive oxygen species (ros) metabolism and aerenchyma formation. this review compiles key findings that help to explain the trait of tolerance to root hypoxia in woody fruit species, giving special attention to their strategies for managing the energy crisis. finally, research challenges addressing less-explored topics in recovery and stress memory in woody fruit trees are pointed out. keywords: hypoxia; waterlogging; fruit trees; prunus; aerenchyma; hypertrophied lenticels; anaerobic fermentation; energy metabolism; root respiration . introduction plants are aerobic organisms and sensitive to many external conditions that could alter internal homeostasis. o deficiency or deprivation trigger hypoxia or anoxia stress, respectively, depending on the o concentrations. plants can face hypoxic conditions from different origins: developmental hypoxia, in plant–microbe interactions, or environmental hypoxia (waterlogging/submergence) [ ]. plants , , ; doi: . /plants www.mdpi.com/journal/plants http://www.mdpi.com/journal/plants http://www.mdpi.com https://orcid.org/ - - - https://orcid.org/ - - - https://orcid.org/ - - - http://www.mdpi.com/ - / / / ?type=check_update&version= http://dx.doi.org/ . /plants http://www.mdpi.com/journal/plants plants , , of currently, the cultivation surface of fruit trees in mediterranean and subtropical areas is approximately million hectares. of this group, % corresponds to olive trees, % to citrus, % to stone fruit, % to vines and % to pome fruit [ ]. fruit trees of the mediterranean climate, such as walnut (juglans regia l.), apple (malus sylvestris l.) or sweet cherry (prunus avium l.), show a low tolerance to hypoxia compared to trees from wetland areas [ ]. in addition, most of these fruit trees do not have the capacity for acclimatization, or even for the recovery of their physiological and growth parameters while flooded, unlike tree forest species of the wetland areas [ – ]. however, several studies have described some hypoxia–tolerance gradient among fruit trees [ – ]. in the context of fruit production, rootstocks are selected for rooting and grafting capacity, abiotic and biotic stress tolerance, and their ability to beneficially alter scion phenotypes, especially in yielding terms. in perennial and some vegetable crops, grafting is used to join resilient root systems (rootstocks) to shoots (scions) that produce the harvested product [ ]. the hydraulic architecture of rootstocks becomes of fundamental importance, since the sustained flow of water controls many plant processes, such as growth, mineral nutrition, scion photosynthesis and transpiration [ ]. species of prunus used as rootstocks are classified as moderately sensitive to root hypoxia, although differences among genotypes regarding their ability to tolerate this stress have been reported [ , – ] mediterranean agriculture has coevolved with harsh environments and changing climate conditions over millennia, generating an extremely rich heritage, but actual climatic change threatens global agriculture especially given the prevalence of highly specialized, low diverse agroecosystems [ ]. the impact of global warming plus a human population hovering around . billion strongly challenges agricultural systems, and the need for a better understanding of how crops and fruit trees can survive and yield under more extreme climatic events becomes of paramount importance, since an increase in precipitation intensity and variability would increase the risks of flooding [ ]. nowadays, as a consequence of global climate change, there are areas of the planet most exposed to intense rains where accumulated amount of water can lead to soil saturation, with a concomitant displacement of o in the rhizosphere. however, although less discussed, it is important to note that there are a number of conditions, beyond excess rainfall, that can configure the establishment of o deficiency at the root level. . edaphic conditions that promote o deficiency the air capacity of the soil is determined by its texture and structure. coarse-textured soils can have an air capacity of around %, while in fine-textured soils the air capacity can reach % [ ]. however, when the structure is altered by physicochemical processes or mechanical forces, the macroscopic pores tend to disappear, so a strongly compacted soil may contain less than % air by volume at its characteristic field-capacity value of soil moisture [ ]. fine texture and compaction associated with bad irrigation practices are able to generate an excess of water sufficient for establishing an o deficit at rhizosphere level. silt and clay particles reduce soil aeration because they are tightly packed together, decreasing the air spaces between them and slowing the drainage [ ]. this condition creates an o deficient environment for plants by maintaining high moisture on the soil surface [ ]. in fine-textured soils, transient soil waterlogging can be generated only by poor irrigation management [ ]. soil compaction occurs primarily when pressure exerted on the soil surface reduces the air spaces between soil particles, and it is associated with agricultural practices, but it can also be the result of natural processes unrelated to the application of compressive forces [ ]. this results in a change in the proportion of pores with water and air (mainly loss of coarse pores), and an increase in mechanical resistance to root development [ , , ]. the soil compaction may be superficial or even reach mm or more [ ], which could have an important impact on the perennial fruit tree’s development. in almond, a field experiment was performed using a heavy tractor to evaluate the continuous transit of agricultural machinery over the soil simulating multiple applications. the authors concluded that the continuous heavy tractor traffic causes an evident soil plants , , of compaction ( – cm deep) with a drastic decrease in soil porosity reaching up to %, and it also produced an increase in bulk density and cone index in subsoil layers [ ]. plants need an adequate supply of air and water in the soil pore space for their suitable development and growth [ ]. the rate of the transfer of gases in the air phase is generally much greater than in the water phase; hence soil aeration depends largely on the volume fraction of air-filled pores [ ]. typically, the requirement for plant development is for at least % of the soil volume to comprise gas-filled pores at field capacity (air capacity), and for at least % of the gas in these pores to be o [ ]. cook and knight [ ] determined that when the air-filled porosity of the soil drops below %, the root respiration and the exchange of o and co between the soil and the atmosphere is hampered. kawase [ ] points out that when it drops below %, hypoxia is triggered, and under more drastic conditions it becomes in anoxia. hypoxia/anoxia conditions restrict processes such as plant respiration, water and nutrient absorption. anaerobic conditions in the soil induce a series of physical, chemical and biological processes, such as ph and redox potential, resulting in changes to the soil’s elemental profile [ ]. o deficiency further affects microbial communities and microbial processes in the soil [ ]. once free o is consumed, nitrate is used by soil microorganisms as an alternative electron acceptor to continue their respiration. the following acceptors are mno , fe(oh) , so − and co [ ]. this generates an increase in the levels of reduced compounds, such as mn +, fe +, h s, nh + and organic compounds (alkanes, acids, carbonyls, etc.) [ , ]. these solutes can accumulate up to phytotoxic levels and contribute to plant injury [ ]. . fruit tree responses to o deficiency . . physiological and biochemical response of fruit trees under o deficiency under hypoxia stress, it has been observed that the gas exchange parameters are dramatically affected in several fruit trees, such as avocado (persea americana mill.) [ ], kiwi fruits (actinidia chinensis planch) [ ], citrus trees [ – ], pecans (carya illinoensis k. koch) [ ], walnut trees (juglans regia l.) [ ], grapevine (vitis vinifera l.) [ , ], pomegranate (punica granatum l.) [ ], apple (malus × domestica borkh) [ ] and several prunus species [ , – ]. in general, all these tree species were classified as sensitive to root hypoxia. however, the concept of “relative tolerance” to hypoxia applied to the fruit tree species must be viewed with caution as many factors, such climatic, experimental or edaphic conditions, among others, could influence the responses observed [ ]. however, some classifications have been made: extremely tolerant—quince (cydonia oblonga mill.) and pyrus betulaefolia; very tolerant—pear (pyrus spp.); moderately tolerant—apple (malus × domestica borkh), citrus spp., and plums (prunus domestica l. and prunus cerasifera ehrh); moderately sensitive—plum (prunus salicina lind.); very sensitive—cherry (prunus avium l); extremely sensitive, peach (prunus persica batsch); and most sensitive—almond (prunus dulcis [mill.] da webb) and apricot (prunus armeniaca l.) [ ]. in the particular case of prunus species, a tolerance gradient to long-term hypoxia was reported among seven genotypes used as rootstocks, identifying as tolerant to ‘mariana ’ (prunus cerasifera × prunus munsoniana w. wight and hedrick) a plum rootstock, and as the most sensitive to ‘mazzard f / ’ (p. avium) a cherry rootstock [ ]. ‘mariana ’ plants survived through days of waterlogging treatment, showing similar stomatal conductance and co assimilation rate values between waterlogged and control plants, unlike in the hypoxia-sensitive genotype, which showed intense leaf and root damage and a drastic decrease in the gas exchange parameters of the leaves during root hypoxia [ ]. the ability to maintain a high photosynthetic rate, such as that observed in hypoxia-tolerant species, would guarantee an adequate supply of carbohydrates from the leaves to the roots. the carbohydrate supply is correlated with the production of highly energetic molecules (atp), and the level of carbohydrate reserves or the capacity to maintain their transport throughout the plant appears to be a key feature in the tolerance to long-term flooding [ , – ]. consequently, plants , , of maintaining glycolysis by a steady and sufficient supply with carbohydrates seems to be crucial for survival under hypoxia [ ]. one of the first responses to o deprivation is a hydraulic adjustment, the purpose of which is to sustain a constant water supply from roots to shoots, which is essential to maintaining gas exchange parameters in hypoxia-tolerant species [ , ]. root hydraulic conductance is also affected under hypoxia stress, usually decreasing this parameter, but the response would depend on the species, age and even the experimental set-up [ ]. there is a huge body of literature about the importance of root water transport in plants under different abiotic stresses (reviewed in [ – ]). in this context, root hypoxia modifies the root water transport in different manners: ( ) cellular acidosis and the depletion of atp affect the phosphorylation of aquaporins and the transport through these water channels is inhibited [ ]; ( ) hypoxia can alter root structure by inducing suberization (generation of a radial oxygen loss (rol) barrier), but at the same time, this modification can affect the apoplastic water transport [ ]; and ( ) massive damage of the root system [ , ]. after days of long-term waterlogging, the hypoxia-tolerant genotype “mariana ” showed similar values of root hydraulic conductance (kr) between normoxic and waterlogged plants. unlike these, the hypoxia-sensitive genotype showed a strong decrease in kr triggered by hypoxia (pimentel, unpublished data). reactive oxygen species (ros) are by-products of various metabolic pathways and are generated enzymatically or nonenzymatically [ ]. nonenzymatic ros production can occur in mitochondria and chloroplast through electron transport chains (etc) [ – ]. enzymatic ros production can occur in peroxisomes, cell walls, plasma membrane and apoplast [ ], and also through respiratory burst oxidase homologs (rbohs), a plasma-membrane-bound nadph oxidase [ , ]. ros induce [ca +]cyt elevations by activation of the specialized ca +-permeable ion channels in the plasma membrane. in addition, nadph oxidases (rbohs) are directly activated by cytosolic ca +. both ros and ca + form a self-amplifying loop named “ros-ca + hub” [ ]. elevation of [ca +]cyt under hypoxia triggers multiple metabolic events and it is associated with both early and late responses to low oxygen conditions (deeply reviewed in [ ]). ros generated in response to abiotic stresses may be involved in various responses, acting as signaling molecules or triggering ros-induced cell death [ ]. under hypoxic stress conditions, ros can be generated due to an impairment of photosynthesis and aerobic respiration processes by inhibiting metc [ , , ]. in some cases, re-oxygenation of the soil after prolonged flooding can cause severe oxidative damage to the roots of sensitive trees [ , ]. indeed, re-oxygenation has been recognized as an abiotic stress that can injure plants post-submergence (reviewed in [ , ]) in a re-analysis of the transcriptome published by arismendi et al. [ ] (commented on in section ), it was possible to find three differentially expressed isoforms of the rboh gene, rboha, rbohc and rbohe. rboha and rbohe genes showed a similar pattern between the two rootstocks, being that both genes were upregulated in hypoxic conditions. on the other hand, the rbohc gene was downregulated in the hypoxia-tolerant genotype ‘mariana ,’ but induced in the sensitive one under hypoxia stress (table ). interestingly, the rbohc gene has been reported as principally expressed in roots, where it is related to root hair formation and primary root elongation and development in arabidopsis [ ]. ros have been described as toxic molecules generated by aerobic respiration that can cause oxidative damage. however, ros also play a key role in signaling to trigger several processes such as cell proliferation and differentiation [ ]. the hypoxia-sensitive genotype response suggests an ros signaling role in the early stages of o deficiency. thus, ‘mazzard f / ’ could activate the formation of new roots, possibly replacing the original root system progressively injured in hypoxia. plants , , of table . transcript levels (of genes related to ros production (rboh) and ros scavenging (sod, cat and apx)) from transcriptomics data from prunus rootstocks under hypoxia. heading log fc ‘mariana ’ ‘mazzard f / ’ gene h h h h h h rboha prupe. g . . . . . . rbohc/rhd prupe. g − . − . − . . . . rbohe prupe. g . . . . . . cu zn sod prupe. g − . − . − . − . − . − . cu zn sod prupe. g . . . − . − . − . cu zn sod prupe. g . . . . . . fe sod prupe. g . . . . . . cat prupe. g . − . − . nd nd nd cat prupe. g . − . − . . − . − . apx prupe. g . . . . . . apx prupe. g − . − . − . − . − . − . apx prupe. g . − . − . . − . − . apx prupe. g . . . . . . apx prupe. g . . − . . . . apx s prupe. g − . − . − . − . − . − . fc: fold change; nd: no detected value. as ros accumulates after hypoxic events, the probability of the cell membrane being involved in a lipoperoxidation process is increased. malondialdehyde (mda) and electrolyte leakage are widely used as indicators of oxidative damage in plants. differences in the accumulation of mda have been reported under hypoxia, which depend on the degree of tolerance of the genotypes evaluated. for instance, in citrus species, the most tolerant genotype showed a delayed accumulation of mda in leaves and roots in comparison with the other genotypes under hypoxia conditions [ ]. hypoxia treatment dramatically increased mda content in the roots of two malus species, but higher concentrations of h o and superoxide radicals (o •–) were detected in the hypoxia-sensitive species [ ]. in prunus rootstocks under long-term hypoxia, ‘mariana ’ plants, the hypoxia-tolerant genotype, showed no significant changes in mda concentration in roots and leaves in comparison with the control plants. opposingly, the sensitive rootstock ‘mazzard f / ’ showed a higher mda concentration in roots and leaves after seven days of waterlogging, suggesting less capacity to remove ros than the tolerant genotype [ , ]. along with a lower mda content in the roots of the hypoxia-tolerant genotype, a lower electrolyte leakage rate was also observed. both parameters evidenced lesser structural damage in the roots, and are related to higher root membrane stability in ‘mariana ’ [ ]. plants have enzymatic and non-enzymatic antioxidant compounds that participate in ros detoxification, reducing the phytotoxic effects of radical species at the cellular level [ , ]. in citrus trees, a higher tolerance to o deficiency by flooding is associated with the ability to delay the apparition of oxidative damage caused by a high activity of antioxidant enzymes such as superoxide dismutase (sod), ascorbate peroxidase (apx), glutathione reductase (gr) and catalase (cat) [ ]. in citrumelo trees, the induction of sod, apx and cat enzyme activities allows them to maintain a transient tolerance under hypoxia [ ]. similar results were observed in malus [ ] and prunus species under hypoxia [ ]. however, different results were found by amador et al. ( ), since an increase in cat activity in short-term waterlogging was found in the hypoxia-sensitive hybrid ‘felinem’, but not in the hypoxia-tolerant rootstock ‘myrobalan’. the authors mention that they cannot conclude that antioxidant enzymes are directly involved in the tolerance of the hypoxia-tolerant genotype. the re-analysis of arismendi et al. [ ] evidenced that, in general terms, there are no notable differences in the expression of the sod, cat and apx genes between the hypoxia-sensitive and hypoxia-tolerant genotypes, except in two cases. in the first one, the cuznsod gene showed an upregulated expression pattern in the hypoxia-tolerant genotype, and a significant downregulation in the hypoxia-sensitive plants , , of one. in the second case, the apx gene showed upregulation in both genotypes, but with a significantly higher expression in the tolerant one (table ). these results could explain the differences in mda content and electrolyte leakage between the prunus rootstocks, since the belated rise in the mda concentration and electrolyte leakage in the root hypoxia-sensitive genotype suggests a lesser capacity to remove ros, implying the occurrence of massive tissue damage which compromises the survival of the plant, as reported by pimentel et al. [ ] and toro et al. [ ]. . . morpho-anatomical changes in fruit trees under o deficiency roots are the first organ that directly sense and deal with o deficiency in compacted waterlogged or flooded soils. therefore, morpho-anatomical modifications that allow the maintaining of better root oxygenation in waterlogging conditions are one of the key mechanisms associated with hypoxia-tolerant genotypes [ ]. adventitious roots, hypertrophied lenticels and aerenchyma all contribute to oxygenating the root system under low o conditions [ , ]. adventitious roots are produced in the replacement of damaged root systems, and are usually thicker and have more intercellular gas-filled spaces than roots growing in well-aerated soil [ ]. hypertrophied lenticels and aerenchyma favor o diffusion to the root tips and rhizosphere, and in addition the hypertrophied lenticels allow the outwards diffusion of potentially toxic compounds like ethanol, acetaldehyde, ethylene and co [ , , ]. in annual crops, both hypertrophied lenticels and the formation of aerenchyma generate a snorkel effect that keeps the roots oxygenated under waterlogging conditions [ ], and eliminate toxic products generated from lactic and ethanol fermentation [ , ]. another anatomical modification in roots is the development of the radial oxygen loss (rol) barrier observed in many wetland plants. this barrier promotes longitudinal o diffusion down roots, restricts the o loss to the soil and could reduce the entry of phytotoxins into the roots in waterlogged soils [ – ]. this root trait has been not identified or studied in hypoxia-tolerant woody and perennial upland fruit trees yet. the generation of morpho-anatomical modifications has been observed in different fruit tree species. hypoxia-tolerant apple rootstocks generated adventitious roots in response to intermittent waterlogging events [ ]. the development of hypertrophied lenticels as a response to root hypoxia has been reported in rosaceae species such as pyrus spp. and cydonia oblonga (mill.) [ ]. pistelli et al. [ ] reported the formation of adventitious roots in prunus cerasifera l. (‘mr.s. / _rootstock’) under waterlogging stress, but they did not report the development of aerenchyma. pimentel et al. [ ] reported that the hypoxia-tolerant prunus rootstock ‘mariana ’ was able to develop adventitious roots, aerenchyma in adventitious roots and hypertrophied lenticels days after the onset of waterlogging treatment. a large adventitious root system grew from the stem base and just beneath the water surface. in this new root system, aerenchyma tissue was not observed near the root apex, but was widely developed distant from it (at and mm from the root apex) and, at the same time, the development of hypertrophied lenticels on the submerged portion of stems was observed (figure ). hypertrophied lenticels appear in wetland species and in several woody and herbaceous plant species subjected to waterlogging [ , , ]. in prunus rootstocks, the hypertrophied lenticels were developed only in the hypoxia-tolerant genotypes, and when the submerged stems of the rootstock ‘mariana ’ were sealed with lanoline to prevent its development, a significant decrease in gas exchange parameters was detected in comparison with the non-lanoline-treated plants [ ]. interestingly, toro et al. [ ] showed that aerenchyma formation also takes place in the existing root system in ‘mariana ’ at mm from the root apex (figure ). in woody plants, all these morpho-anatomical modifications are late responses. in the case of long-term hypoxia treatment, they appear after or days from the beginning of the stress, and they are part of the strategies used to avoid the negative effects of the energetic crisis triggered by an o deficient environment. plants , , of . transcriptomic reprogramming of principal pathways involved in energy metabolism under o deficiency the effect of o deficiency on the rhizosphere of woody plant species has been more widely addressed from a physiological perspective than from a genomic point of view. despite the massive amount of data provided by next generation sequencing analyses (ngs), which would allow a more integrative view of the plant’s response to root hypoxia stress, few transcriptomic studies have been reported in woody species [ – ] and fruit trees such as avocado [ ] prunus sp. [ , , , ], kiwi fruit [ ] and grapevine [ , ]. using rna-seq time series data from our collaborative study on prunus rootstocks previously reported [ ], a revisited analysis with a de novo assembly approach was carried out in order to gain a deeper insight into the relevant pathways involved in energy metabolism under hypoxic conditions. the de novo assembly evidenced a higher number of differentially expressed genes (degs) in the hypoxia-sensitive prunus rootstock ‘mazzard f / ’ at each of the sampling times of the waterlogging treatment, in comparison to the hypoxia-tolerant rootstock ‘mariana ’ ( h: vs. ; h: vs. and h: , vs. ). specifically, those rna-seq analyses focused on the hypoxia adaptation of root systems [ , , , , ] have evidenced certain metabolic pathways and groups of genes commonly affected by o deficiency. maintaining a continuous glycolytic flux is a crucial factor in ensuring the energy pool necessary for the processes involved in the survival of trees under hypoxia [ ]. in woody species, it has been reported that hypoxia-sensitive plants deplete their soluble sugars rapidly in flooded conditions, but the tolerant ones keep a higher level of soluble sugars for longer periods [ , , ]. in this context, the regulation of gene expression involved in primary metabolism and energy homeostasis is essential to avoiding the detrimental effects of energy depletion under hypoxic stress. in the sweet cherry rootstock cerasus sachalinensis (f. schmidt), the waterlogging treatment upregulated most genes associated with sucrose metabolism. genes encoding sucrose synthase (susy) were upregulated, however invertase (inv) genes were downregulated [ ]. in ‘mariana ’ and ‘mazzard f / ’ plants, four susy isoforms were upregulated under hypoxic conditions. additionally, in ‘mazzard f / ’ rootstocks, one inv isoform was upregulated after h of waterlogging treatment, and four were downregulated at the same time. on the other hand, ‘mariana ’ rootstocks exhibited three inv isoforms downregulated at and h (figure ). both susy and inv can cleave sucrose to release its constituent monosaccharides, although a lower energy cost of generating hexose phosphates for glycolysis is required in the case of sucrose synthase. this latter is a typical feature of sucrose metabolism during o deficiency [ ]. thus, those plants that favor the activity of susy would be opting for a more energy efficient way to provide substrates for glycolysis under hypoxic conditions. transcriptomic evidences in the roots of waterlogged forestry trees revealed enhanced glycolytic flux and an activation of fermentative pathways in order to maintain the energy supply when mitochondrial respiration is inhibited by o deficiency [ , ]. alongside the induction of genes related to glycolysis, an absence of transcripts for genes associated to gluconeogenesis, such as glucose -phosphatase and fructose , -bisphosphatase, was reported in roots of flooded avocado (persea americana mill.) [ ]. in this sense, the downregulation of phosphoglucomutase genes reported in flooded grapevine roots also supports the idea of a hampered flux to gluconeogenesis under o deficiency [ ]. this pattern was also presented in myrobalan ‘p. ’, another hypoxia-tolerant prunus rootstock, but not in the hypoxia-sensitive ‘felinem’ [ ]. in the prunus rootstock ‘mariana ’, two phosphoglucomutase isoforms were downregulated at and h of waterlogging treatment, but the gene induction of two isoforms detected in ‘mazzard f / ’ plants after h of o deficiency is worth noting (figure ). furthermore, genes encoding for phosphoenolpyruvate carboxykinases (pepck) repeated the behavior described for phosphoglucomutase in these prunus rootstocks contrasting in their tolerance to hypoxia (figure ). regarding the above-mentioned, the inhibition of gluconeogenesis appears to be strongly related to hypoxia-tolerant genotypes in prunus spp. plants , , of hexose-phosphorylating hexokinases (hxk) are the only plant enzymes able to phosphorylate glucose, so they are considered a key factor in glycolysis activation [ ]. the hypoxia-tolerant prunus rootstock ‘mariana ’ evidenced the induction of more hxk genes than the hypoxia-sensitive ‘mazzard f / ’, and what is more, the hexokinase (prupe. g ) was strongly upregulated in the tolerant genotype, but consistently downregulated in the sensitive one during the whole hypoxia treatment (figure ) [ ]. plants , , x for peer review of hexose-phosphorylating hexokinases (hxk) are the only plant enzymes able to phosphorylate glucose, so they are considered a key factor in glycolysis activation [ ]. the hypoxia- tolerant prunus rootstock ‘mariana ’ evidenced the induction of more hxk genes than the hypoxia-sensitive ‘mazzard f / ’, and what is more, the hexokinase (prupe. g ) was strongly upregulated in the tolerant genotype, but consistently downregulated in the sensitive one during the whole hypoxia treatment (figure ) [ ]. figure . transcriptomic reconfiguration of pathways involved in energy metabolism in response to o deficiency. through a comparative analysis between two genotypes of prunus rootstocks, the hypoxia-tolerant ‘mariana ’ (‘m ′) and the hypoxia-sensitive ‘mazzard f / ’ (‘f ′), the figure . transcriptomic reconfiguration of pathways involved in energy metabolism in response to o deficiency. through a comparative analysis between two genotypes of prunus rootstocks, the hypoxia-tolerant ‘mariana ’ (‘m ′) and the hypoxia-sensitive ‘mazzard f / ’ (‘f ′), the changes plants , , of in the transcript levels of genes belonging to the routes typically related to energy metabolism (starch/sucrose, glycolysis/gluconeogenesis and lactic/ethanolic fermentations) and that are expressed in a contrasting way between the genotypes are described. along with these routes, their connections to tca cycle, gaba shunt and the gs/gogat cycle are presented. the differential transcript levels of the genes of the last two pathways show clear differences that point to the favoring of one or another metabolic pathway in a genotype-dependent manner. in addition, the steps where the regeneration of nad+, consumption of excess h+ (regulation of cytoplasmic ph) and assimilation of nh + take place are shown. the data included in this re-analysis were obtained through a de novo approach via rnaseq data retrieved from ncbi bioprojects prjna and prjna [ ], corresponding to p. cerasifera ×p. munsoniana ‘mariana ’ and p. avium ‘mazzard f / ’, respectively. quality control of the libraries was performed with fastqc and the afterqc tool [ ]. consecutively, all libraries were merged into one unique file to perform a de novo assembly with trinity [ ]. the resulting fasta file was depurated to obtain unigenes using transdecoder with the pfam database [ ] and cd-hit-est [ , ]. this output was used as a reference to perform an alignment using hisat [ ]. transcript assembly was performed through stringtie [ ]. degs were obtained using edger from bioconductor [ ]. genes with adjusted p-value < . and logfc > & <− were used for further analysis. the annotation was performed using go feat [ ] and kegg [ ]. degs included in this figure are indicated with their homolog loci from p. persica: susy—( ) prupe. g . ; ( ) prupe. g . ; ( ) prupe. g . ; ( ) prupe. g . . invertase—( ) prupe. g . ; ( ) prupe. g . ; ( ) prupe. g . ; ( ) prupe. g . ; ( ) prupe. g . . hexokinase —( ) prupe. g . snrk , —( ) prupe. g . . phosphoglucomutase—( ) prupe. g . ; ( ) prupe. g . . pepck (atp)—( ) prupe. g . ; ( ) prupe. g . . pepck (gtp)—( ) prupe. g . ; ( ) prupe. g . ; ( ) prupe. g . ; ( ) prupe. g . ; ( ) prupe. g . . dhlta—( ) prupe. g . ; ( ) prupe. g . . glutamate synthase—( ) prupe. g . . glutamine syntethase—( ) prupe. g . ; ( ) prupe. g . ; ( ) prupe. g . ; ( ) prupe. g . ; ( ) prupe. g . . gdh—( ) prupe. g . ; ( ) prupe. g . . gad—( ) prupe. g . ; ( ) prupe. g . . for more detailed results of the transcriptional patterns of ldh, pdc and adh (quantitative reverse transcription (qrt)-pcr) and alanine levels (hplc-dad) inserted in this figure, refer to [ , ]. as a product of the phosphorylation of glucose by hxk, glucose -phosphate (g p) can block sucrose-non-fermenting-related protein kinase- (snrk ) activity [ ]. snrk is a kinase recognized as a metabolic sensor that can decode energy deficiency signals and induce the extensive metabolic reprogramming required for the adaptation to nutrient availability through inhibition of expensive energy processes and growth arrest. stress conditions, such as hypoxia, can affect photosynthesis and photoassimilates biosynthesis along with respiration triggering a low energy syndrome (tomé et al., ). transcriptomics data evidenced the induction of snrk genes majorly associated with the hypoxia-sensitive prunus rootstocks ‘felinem’ [ ] and ‘mazzard f / ’ (figure , this review). remarkably, low levels of g p induce the activity of snrk , which triggers the signaling for upregulating several genes such as pepcks, commented on above. regarding the genes encoding glycolytic enzymes, these two genotypes exhibited similar transcriptional activation between them, without significant differences in response to waterlogging. in grapevine, an upregulation of diphosphate-dependent phosphofructokinases, instead of atp dependent -phosphofructokinases , was found, responsible for converting d-fructose -phosphate to d-fructose , -bisphosphate, which is another typical feature of the glycolysis in hypoxia that favors energy saving through ppi-dependent rather than atp-dependent processes [ ]. in order to maintain atp production by the glycolytic pathway, it is necessary to replenish the nad+ pool that was reduced during this process. in this context, activation of the fermentative pathways results in the classic and most widely reported response in the anaerobic metabolism. from pyruvate, lactic and ethanolic fermentation generate lactate and ethanol, respectively, and in the process nadh is oxidized, returning nad+ to keep glycolysis active [ ]. however, both fermentative pathways present eventual disadvantages, since lactate is toxic for the cells, and ethanol diffuses rapidly plants , , of out of the cells, implying a considerable loss of carbon under hypoxic conditions [ ]. the gene induction of lactate dehydrogenase (ldh) in fruit trees under root hypoxia has been reported in avocado [ ], prunus spp. [ , ] and c. sachalinensis [ ], but not in grapevine [ ] or the prunus genotypes analyzed by rubio-cabetas et al. [ ]. in ‘mariana ’ and ‘mazzard f / ’, root hypoxia triggered a rapid increase in the ldh (prupe. g ) mrna levels with a peak in their transcripts at six hours, but such increase was more dramatic and prolonged in the root hypoxia-sensitive genotype (figure ) [ ]. consequently, a higher l-lactate content was evidenced in ‘mazzard f / ’ roots with a maximum at and h of waterlogging. an increase in ldh activity in response to waterlogging in three species of prunus (p. mira, p. persica and p. amygdalus) indicated that p. amygdalus was the genotype with a greater and more sustained increase in ldh activity. this fact was concomitant with its increased accumulation of lactic acid in the cytoplasm, and its lower tolerance to root hypoxia [ ]. lactate accumulation and cytoplasmic acidosis are determinants of hypoxia-sensitive phenotypes in maize [ ]. in addition, in limonium spp., plants capable of removing excesses of lactate from the cytoplasm were more tolerant to hypoxia conditions [ ]. in this sense, the increase of prunus spp. nip ; mrna, a putative lactic acid transporter, was not linked to a lower lactate content in the roots of ‘mazzard f / ’. bioinformatic approaches identified steric hindrances in pruavnip ; given by the residues phe and trp in the npa region and ar/r filter, respectively, but such blockages were absent in the nip ; of ‘mariana ’. the functional characterization of these aquaporins in the yeast strain ∆jen corroborated the lower efficiency of the lactic acid transport of pruavnip ; , which could be related to a higher lactate accumulation and detrimental effects at cell level in ‘mazzard f / ’ roots under hypoxia [ ]. the drop in cytoplasmic ph, in part related to the dissociation of lactic acid, inhibits ldh activity and stimulates that of pyruvate decarboxylase (pdc), the first step involved in ethanol fermentation [ ]. pdc and alcohol dehydrogenase (adh) transcripts were found to be expressed in each transcriptome analyzed. both pdc and adh transcripts were coordinately induced in ‘mariana ’ and ‘mazzard f / ’ under o deficiency, although the hypoxia-tolerant genotype showed a decreasing trend after h of waterlogging (figure ) [ ]. this transcriptional finding suggests that ‘mariana ’ resorts to other adaptation mechanisms, distinct to the fermentation pathways, after the first hours of flooding. the pyruvate dehydrogenase complex catalyzes the oxidative decarboxylation of pyruvate with the formation of acetyl-coa, co and nadh(h+) [ ], linking glycolysis to the tricarboxylic acid (tca) cycle. interestingly, transcripts of the subunit e (dihydrolipoyl trans-acetylase, dhlta), a component of this enzymatic complex, were downregulated in both ‘mariana ’ and ‘mazzard f / ’ roots under hypoxic conditions; however, this repression was earlier and much stronger in the hypoxia-tolerant prunus rootstock (figure ). this fact suggests a diminished metabolic flux in the tca cycle and an accumulation of pyruvate. however, another conclusion for pyruvate as a result of o deficiency, different from the fermentative pathways, is its conversion to alanine by means of the enzyme alanine aminotransferase (alaat). the accumulation of this amino acid is typically linked to hypoxia in plants [ , , ]. alaat mrnas induced during hypoxia were reported in the roots of avocado [ ], grapevine [ ] and myrobalan ‘p. ’ [ ]. although alaat transcripts were not detected in the transcriptome of ‘mariana ’ or ‘mazzard f / ’, the accumulation of alanine was evidenced in both genotypes during waterlogging, this being more intense in the hypoxia-sensitive genotype (figure ) [ ]. a hypoxia-induced alanine accumulation is also possible through the activity of gaba-transaminase (gaba-t) that converts gaba into succinic semialdehyde (ssa), releasing alanine (from pyruvate) to the mitochondrial lumen [ , ]. here, the eventual ssa accumulation will be toxic for the cell. the succinic-semialdehyde dehydrogenase (ssadh) converts ssa into succinate, consuming an nad+ molecule [ ] but this latter would limit the ability of the cell to properly maintain the active glycolysis. another alternative means of draining pyruvate to alanine by alaat under hypoxic conditions involves the glutamate metabolism. the reductive amination of -oxoglutarate by glutamine plants , , of oxoglutarate amino transferase (gogat) regenerates glutamate (substrate of alaat to produce alanine) and nad+ (diab and limami, ). interestingly, root hypoxia induced gogat in ‘mariana ’ rootstock, but not in the hypoxia-sensitive ‘mazzard f / ’, whose transcript levels remained unchanged under waterlogging (figure ). it is possible that a higher gogat enzyme activity is related to the higher metabolism of alanine in ‘mariana ’, which would explain the modest accumulation of this amino acid during waterlogging in this genotype, as opposed to the notorious accumulation shown by the hypoxia-sensitive prunus rootstock (figure ) [ ]. in flooded grapevine, gogat, glutamine synthetase (gs) and glutamate dehydrogenase (gdh) were overexpressed [ ]. gs catalyzes the atp-dependent assimilation of nh + into glutamine using glutamate as substrate. the gs/gogat cycle is the principal route of ammonium assimilation in plants [ ]. in tomato (solanum lycopersicum l.), the activity of the atp-consuming gs was significantly enhanced in roots during prolonged root hypoxia [ ]. here, a striking contrast in the gs transcriptional pattern was evidenced between ‘mariana ’ and ‘mazzard f / ’ roots under hypoxic conditions, as gs transcripts were strongly accumulated in the hypoxia-tolerant genotype after h of waterlogging, but consistently downregulated as stress progressed in the hypoxia-sensitive one (figure ). this evidence suggests that a more active gs/gogat cycle, capable of assimilating nitrogen and regenerating nad+ to support glycolytic flux under conditions of o deficiency, shapes one of the successful metabolic strategies involved in defining the hypoxia-tolerant phenotype seen in ‘mariana ’. as in the flooded grapevine, gdh transcripts were overexpressed in the roots of waterlogged ‘mazzard f / ’, but clearly downregulated in the hypoxia-tolerant genotype (figure ). another gene involved in the gaba shunt, glutamate decarboxylase (gad), showed an upregulation only associated with the hypoxia-sensitive genotype (figure ). thus, ‘mazzard f / ’ appears to boost the flux of the gaba shunt by acquiring glutamate from gdh-mediated -oxoglutarate amination (instead of from its inhibited gs/gogat cycle). this amination generates nad+, but the detoxification of the ssa consequently generated in this pathway, through ssadh activity, consumes nad+, so the net gain of this cofactor is . the transcriptomic antecedents compiled from different fruit trees under hypoxic conditions show common alterations of genes involved in starch/sucrose metabolism and glycolysis, together with the inhibition of gluconeogenesis in the case of hypoxia-tolerant genotypes. the activation of, firstly, lactic fermentation (ldh), and then ethanolic fermentation (pdc and adh), was also evident in all fruit trees. since ethanol can represent a carbon leak from the plant, a more energy-efficient destination for pyruvate is its conversion to alanine. at this point, the regeneration of the glutamate involved in alanine biosynthesis from the gs/gogat cycle instead of from the gdh activity in the context of gaba shunt is postulated as one of the best metabolic strategies for explaining the survival and growth capacity during o deficiency in root hypoxia-tolerant genotypes, such as in the case of the prunus rootstock ‘mariana ’. . root respiration under o deficiency the carbon cycle is a bio-geochemical cycling process of the continuous flowing of organic and inorganic forms of carbon through the biosphere, geosphere and atmosphere, supporting life on earth [ ]. in the biosphere, plants play a key role via autotrophic respiration, which represents an important component of the carbon cycle and corresponds to respiratory processes in the leaf, shoot and root [ ]. respiration involves the participation of different processes responsible for the oxidation of glucose molecules for energy and carbon structures, either in the presence (aerobic) [ , ] or absence (anaerobic) of o [ ]. root respiration is a process sensitive to changes in soil conditions, such as chemical composition [ ], temperature [ ], salinity [ ] and water excess (hypoxia/anoxia stress) [ ], among others. root respiration is highly dependent on the availability of o in the root zone, and a lack of this element may lead plants into an imbalance in energy distribution within metabolic processes, whereby the deficit of atp could range between % and . % with respect to well-aerated roots [ ]. plants , , of when the o in the rhizosphere decreases to a point where the formation of atp by cytochrome oxidase (cox, or complex iv) is hampered, the activation of less efficient metabolic pathways takes place (e.g., fermentative pathways) and plants may enter a state of energy crisis [ ]. the growth and maintenance of tissues are two processes that require energy from root respiration, and must coexist coordinately for the correct development of plants. however, energy crisis caused by hypoxia/anoxia stress (o deficiency) induces an energy redistribution either to the maintenance or the growth of new tissue [ , ]. membrane stability, active ion transport and de novo synthesis of proteins are the most expensive processes whereby the cell metabolism must adjust its energy budget [ ]. it has been reported that these processes are controlled by gene regulation at both the transcript and translation level [ ], and they strategically determine how plants cope with the energy reduction imposed by hypoxia/anoxia. it is well known that low o levels impair the respiratory metabolism of plant tissues. the damage induced by o depletion, especially on root respiration, could compromise the development and growth of the entire plant, because root respiration drives the energetic support for generating new biomass and/or cellular and structural maintenance [ – ]. as previously commented, there is limited information available about transcriptome analysis in trees or woody species under low o conditions, and even fewer works have been reported that relate the differentiated expressions of genes from transcriptomes and the physiological responses of the respiratory metabolism. the respiratory chain has a principal function of transferring electrons to the terminal oxidases, where o acts as the final electron acceptor, producing high-energy phosphate bonds (atp) [ , ]. the mitochondrial oxidative phosphorylation system consists of four multi-subunit oxidoreductases involved in the electron transport chain (metc) (complexes i-iv) and the atp synthase complex (complex v) [ , ]. in the revisited analysis of the transcriptomic study comparing prunus rootstocks contrasting in their tolerance to hypoxia [ ], degs encoding for proteins belonging to the metc, such as respiratory supercomplex factor (rcf ), subunits of complex iii (cytbc (sub ), cytbo and cytb red) and iv (cox(sub b ) and cox(sub b )), cytochrome c (cytc) and alternative oxidase (aox), were detected (figure ). the synchrony of the activity of each protein in the metc may be altered depending on the o availability in the rhizosphere [ ], having as a direct consequence a partially restricted or completely inhibited energy production [ ]. as in herbaceous plants, in woody species one of the most dangerous subproducts of the aerobic metabolism is the formation of ros such as h o and o − [ ]; however, under an anaerobic condition, other harmful molecules are also formed. thus, the combination of ros and nitric oxide (no) may be extremely detrimental for the cell [ , ]. the processes involved in coping with low o at the root level are quite expensive for the plant’s energy budget [ , ], and therefore to scavenge harmful molecules, plants are required to invest a significant amount of energy in synthesizing expensive enzymatic or nonenzymatic molecule scavengers [ ]. in the metc, ros are formed principally through electron leakage from the protein complexes inserted into the mitochondrial membrane, such as complex i (ndh, nadh dehydrogenase) and iii (cytbc , cytochrome bc dehydrogenase) [ ], and no formation is more associated with alternative oxidase (aox), complex iii and iv (cox, cytochrome c oxidase) [ – ]. the revisited analysis of [ ] revealed large differences in gene expression related to metc, which are closely related to proteins of complex iii, iv and aox (figure ). regarding complex iii, no alterations were found in the expressions of the cytb_red and cytbc genes in waterlogged ‘mariana ’ plants, however the gene inductions of these isoforms were evident in the root-hypoxia-sensitive genotype ‘mazzard f / ’ in response to o deficiency (figure ). on the other hand, the root-hypoxia-tolerant ‘mariana ’ repressed the expression of two cytbo isoforms, but ‘mazzard f / ’ showed a different behavior since the three cytbo isoforms were induced in response to hypoxia in both early and late stages (figure ). with respect to complex iv, ‘mariana ’ did not present degs over time, while in contrast, ‘mazzard f / ’ reduced the expression of cox(sub b ) at h, but a strong induction of cox(sub b ) was evident from h of root hypoxia (figure ). some of the protein complexes of the mitochondrial membrane may contribute to the scavenging of these harmful molecules. in this sense, no is formed from nitrite by cox, however, this protein is inhibited by the raised no, while that aox plants , , of is an no-resistant protein [ ]. for instance, it has been found in a. thaliana that the overexpression of aox may prevent excesses of no modulating the formation of onoo− from interacting with o − [ ]. therefore, despite the low affinity of o with aox and the limiting proton translocation, the activity of aox allows the maintenance of the energy balance under hypoxic conditions [ ]. recently, vishwakarma et al. [ ] found an increase in the haemoglobin–nitric oxide (hb/no) cycle under hypoxia, which might be mediated by the aox protein and improves the redox and energy status of the hypoxic cell [ ]. this cycle consumes nadh-regenerating nad+, which would contribute to maintaining the glycotytic flux during o deficiency [ ]. in the roots of prunus rootstock under o deficiency, the class non-symbiotic haemoglobin-like (nshb) gene showed a higher expression in the hypoxia-tolerant genotype than in the sensitive one [ ]. this was also found in roots of hypoxia-tolerant oak genotypes under low o [ ]. in addition, the transcriptomic analysis revealed a higher aox gene expression in ‘mariana ’ at h of waterlogging, but no upregulation of this gene was detected in the sensitive genotype (figures and ). thereby, the participation of class nshb and aox genes in hypoxia tolerance genotypes may suggest that the possibility of the participation of the nshb/no cycle drives energetic support to the roots of woody plants in the early stages of hypoxia, promoting the electron flow [ ] and allowing the prevention of metc overreduction [ ]. plants , , x for peer review of hypoxic conditions [ ]. recently, vishwakarma et al. [ ] found an increase in the haemoglobin– nitric oxide (hb/no) cycle under hypoxia, which might be mediated by the aox protein and improves the redox and energy status of the hypoxic cell [ ]. this cycle consumes nadh- regenerating nad+, which would contribute to maintaining the glycotytic flux during o deficiency [ ]. in the roots of prunus rootstock under o deficiency, the class non-symbiotic haemoglobin-like (nshb) gene showed a higher expression in the hypoxia-tolerant genotype than in the sensitive one [ ]. this was also found in roots of hypoxia-tolerant oak genotypes under low o [ ]. in addition, the transcriptomic analysis revealed a higher aox gene expression in ‘mariana ’ at h of waterlogging, but no upregulation of this gene was detected in the sensitive genotype (figures and ). thereby, the participation of class nshb and aox genes in hypoxia tolerance genotypes may suggest that the possibility of the participation of the nshb/no cycle drives energetic support to the roots of woody plants in the early stages of hypoxia, promoting the electron flow [ ] and allowing the prevention of metc overreduction [ ]. figure . transcriptomic reconfiguration of pathways involved in mitochondrial electron transport chain in response to o deficiency. the changes in the transcript levels of genes belonging to the mitochondrial electron transport chain typically related to energy metabolism, and that are expressed in a contrasting way between the genotypes, are described. data obtained from de novo transcriptomic analysis of ‘mariana ’ (‘m ′) and ‘mazzard f / ’ (‘f ′). aox, alternative oxidase; cytc, cytochrome c; rcf , respiratory supercomplex factor ; cytbo , cytochrome bo ubiquinol oxidase; cytbc (sub ), cytochrome bc complex subunit ; cytb red, cytochrome b reductase; cox(sub b ), cytochrome c oxidase subunit b ; cox(sub b ), cytochrome c oxidase subunit b . to generate an optimal response under hypoxia is necessary in order to activate the complete genetic machinery, which could have an extra cost to the root metabolism [ ]. under hypoxia, the control of protein synthesis may be a ‘double-edged sword’, since this is necessary for proper cell function, but an increase in protein turnover may increase the respiratory costs of maintenance, which might lead to compromised growth [ ]. under optimal conditions, the energy generated in mitochondrial phosphorylation as atp is used to synthesize new structures in growing plants (growth respiration), and for all processes related to cellular maintenance, such as protein turnover, maintenance of ion gradients and membrane potentials in the cell (maintenance respiration) [ , , ]. however, environmental changes may alter the distribution of energy. under waterlogging, the forced entry into a state of energy crisis leads the roots to allocate resources to priority processes, thus modifying the costs associated with root respiration [ ]. in carex plants, o deficiency drives the activation of strategies for reducing root growth in order to maximize the respiratory cost imposed on i upon uptake [ ]. however, the allocation of o to components of root ‘m ’ ‘f ’ mitochondrial etc aox cox(sub b ) cox(sub b ) cytb_red cytbc (sub ) cytbc (sub ) cytbo cytbo cytbo cytc rcf rcf h h h h h h - - logfc alternative oxidase complex iv complex iii cytochrome c respiratory supercomplex factor figure . transcriptomic reconfiguration of pathways involved in mitochondrial electron transport chain in response to o deficiency. the changes in the transcript levels of genes belonging to the mitochondrial electron transport chain typically related to energy metabolism, and that are expressed in a contrasting way between the genotypes, are described. data obtained from de novo transcriptomic analysis of ‘mariana ’ (‘m ′) and ‘mazzard f / ’ (‘f ′). aox, alternative oxidase; cytc, cytochrome c; rcf , respiratory supercomplex factor ; cytbo , cytochrome bo ubiquinol oxidase; cytbc (sub ), cytochrome bc complex subunit ; cytb red, cytochrome b reductase; cox(sub b ), cytochrome c oxidase subunit b ; cox(sub b ), cytochrome c oxidase subunit b . to generate an optimal response under hypoxia is necessary in order to activate the complete genetic machinery, which could have an extra cost to the root metabolism [ ]. under hypoxia, the control of protein synthesis may be a ‘double-edged sword’, since this is necessary for proper cell function, but an increase in protein turnover may increase the respiratory costs of maintenance, which might lead to compromised growth [ ]. under optimal conditions, the energy generated in mitochondrial phosphorylation as atp is used to synthesize new structures in growing plants (growth respiration), and for all processes related to cellular maintenance, such as protein turnover, maintenance of ion gradients and membrane potentials in the cell (maintenance respiration) [ , , ]. however, plants , , of environmental changes may alter the distribution of energy. under waterlogging, the forced entry into a state of energy crisis leads the roots to allocate resources to priority processes, thus modifying the costs associated with root respiration [ ]. in carex plants, o deficiency drives the activation of strategies for reducing root growth in order to maximize the respiratory cost imposed on i upon uptake [ ]. however, the allocation of o to components of root respiration depends on the species. in the hypoxia-tolerant prunus genotype, ‘mariana m ’, toro et al. [ ] found a greater ability of the root growth to spend less energy in processes related to maintenance, such as protein turnover and membrane integrity. these costs could reach up to % of the plant’s energy budget [ ], and therefore its regulation would be a key factor in tolerance to hypoxia. an eukaryotic orthologous groups (kog) classification in cerasus sachalinensis roots under short-term waterlogging showed that the largest groups of degs were included in the categories of post-translational modification, protein turnover, and chaperones [ ]. in addition, the authors found that a high number of transcripts were associated with translation pathways, and also energy metabolism. the revisited transcriptomic analysis showed a remarkable difference between transcripts related to metc from ‘mariana ’ and ‘mazzard f / ’ rootstocks in response to hypoxia. thus, low o in roots increases dramatically the gene expression of the sensitive genotype from to h of waterlogging, whereat one would usually find upregulated genes from subunits of complex iii (cytbo , cytb_red, and cytbc ) and iv (cox(sub b )), and genes that have control over processes associated with supercomplex formation (rcf ) (figures and ). according to arru and fornaciari [ ], protein synthesis would depend on post-transcriptional or post-translational regulation, there being extremely high energy-requiring step at the translational level. a study performed on prunus showed that hypoxia-tolerant rootstocks manifested reduced atp demands for protein turnover and the maintenance of membrane integrity, which was closely related to the low respiratory costs of maintenance [ ]. into the mitochondrial inner membrane, the respiratory protein complexes associate to form supramolecular assemblies known as supercomplexes [ , ]. the supercomplex formation seems to be crucial for the proper functioning of metc, and requires the assistance of specific genes to efficiently assemble its constituent proteins [ ]. in higher plants, the presence of the supercomplex has been identified in several species such as arabidopsis, bean, potato and barley [ ]. however, there is still a lack of information about the genes encoding for proteins involved in supercomplex formation. the respiratory supercomplex factor (rcf ) gene is part of the conserved gene family termed hypoxia-induced gene , which is highly expressed under hypoxia conditions and has been described as necessary for supercomplex formation [ , ]. as for other genes from metc, there are scarce reports about the rcf genes of woody species or even of higher plants. recently, shin et al. [ ] identified the rcf gene from cucumis melo, but further efforts are required to identify this gene in a larger number of woody species and evaluate its response under o deficiency. further, in wheat roots, rcf helps to overcome an energy deficit by enhancing adp/atp transfer and, ultimately, improving the supply of atp [ ]. an early expression of the rcf gene in both hypoxia-tolerant and -sensitive prunus rootstocks is evidenced (figures and ). however, only the hypoxia-tolerant genotype ‘mariana ’ showed expression of aox, while the hypoxia-sensitive genotype ‘mazzard f / ’ showed the expression of genes related to complex iii, and after h also evidenced the expression of genes related to complex iv (figure ). according to eubel et al. [ ], in the metc, complex iii is commonly found, forming a higher (i+iii) and lower (iii+iv) abundance of the supercomplex, and on the other hand, aox does not seem to form part of a supercomplex, because complex i and iii would limit aox activity by reducing substrate ubiquinol. it is has been reported that higher levels of complex i and supercomplex i+iii could contribute directly to the maintenance of mitochondrial function under hypoxia [ ]. the transcriptomic data of metc genes from rnaseq could lead to the proposal that the presence of the aox gene (and consequently aox protein) would not be limited by the presence of genes related to complex iii, which could lead to an over-formation of the supercomplex and reduce the aox protein activity (figure ). in addition, the fact that the ‘mariana ’ rootstock did not express genes related to complex iii or iv, although plants , , of rcf genes were effectively expressed, would indicate an appropriate regulation of the supercomplex in the metc in the tolerant genotype. in the hypoxia-sensitive prunus rootstock ‘mazzard f / ’, a higher energy cost related to protein turnover was reported as being triggered by o deficiency, and root tissue injury triggered by waterlogging [ ]. as consequence, the hypoxia-sensitive genotype should require greater protein synthesis/breakdown, which is partially observed here in the high differential expression of the complex proteins at different times of waterlogging (figure ). metc have several protein complexes with different roles that guarantee the maintenance of cellular energy both under optimal and stress conditions. cytochrome c (cytc) corresponds to a small and conserved protein family that is responsible for generating the proton gradient across complexes iii and iv, driving atp synthesis [ ] and in addition potentially plays a key role in the development of an adaptative mechanism for tolerating low o [ ]. it has been described that the cytc protein may be released (with ros production) from the mitochondrial membrane into the cytosol, to trigger the key step in the early execution phase of programmed cell death (apoptosis) [ , ]. generally, the avoiding strategies of plant adaptation to o deficiency involve the formation of aerenchyma structures by apoptosis, in order to support the increase in o diffusion and maintain the aerobic energy supply in root cells [ , , ]. scarce information for woody species has been reported regarding the relationship between cytc and hypoxia stress [ ]; however, it is widely known that waterlogged woody species are able to develop aerenchyma in the roots through apoptosis [ , , , ]. the cytc-dependent aerenchyma formation relies on the redox state of the cell environment, which will depend on the presence of h o and/or o - [ ]. under hypoxia, there are relatively high concentrations of h o [ ], which would lead the cellular environment to an oxidized state, changing the cytc protein structure into its oxidized state, which is capable of triggering apoptosis [ ]. after h of waterlogging treatment, a higher induction of the cytc gene was detected in the hypoxia-tolerant genotype ‘mariana ’, while no or very low expression was observed in ‘mazzard f / ’ (figures and ). on the other hand, waterlogged ‘mariana ’ plants developed aerenchyma in roots, which would combine with the air-filled spaces in supplying the o needed for aerobic metabolic processes [ , ] (figure ). therefore, we suggest that under low o stress, the overexpression of the cytc gene in an oxidized cell environment could increase the synthesis of cytc proteins, generating a higher concentration of proteins in the cytoplasm, which would support the induction of apoptosis and end with aerenchyma formation (figure ). certainly, in the future, more comprehensive studies with woody plants are required to help understand the steps between cytc gene expression and the modulation of protein synthesis, especially under conditions of o deficiency. plants , , of plants , , x for peer review of figure . schematic overview of principal metc-expressing genes and morpho-anatomical changes in prunus rootstocks under root hypoxia. the figure summarizes the effect of aox and cytc on no and ros generation. regarding ros, the early induction of aox ( h) and the late induction of cytc ( and h) would lead to a regulation of ros accumulation in a temporally non-exclusive way in the root-hypoxia-tolerant prunus rootstock (‘mariana m ’). thus, at the beginning of stress by o deficiency, this genotype would be preventing the accumulation of ros in roots, but as stress progresses, in the context of apoptosis, the elevation of ros levels has been associated with the activity of cytc [ , ]. the generation of aerenchyma mediated by apoptosis present in the original root system, and the generation of adventitious roots with aerenchyma and hypertrophied lenticels, are characteristic features of ‘mariana m ’. these traits are completely absent in the root- hypoxia-sensitive prunus rootstock (‘mazzard f / ’). the generation of air-filled spaces results in an avoidance strategy in relation to o deprivation, which is associated with the maintenance of an adequate metabolism and energy supply at the whole plant level. the blue and red arrows represent the over- and down-expression of genes related to metc. aox, alternative oxidase; cytc, cytochrome c; rcf , respiratory supercomplex factor ; cytbo , cytochrome bo ubiquinol oxidase; cytbc (sub ), cytochrome bc complex subunit ; cytb red, cytochrome b reductase; cox(sub b ), cytochrome c oxidase subunit b ; cox(sub b ), cytochrome c oxidase subunit b ; [no], nitric oxide; [ros], reactive oxygen species. images of morpho-anatomical changes were obtained from [ , ]. this figure was created using biorender. figure . schematic overview of principal metc-expressing genes and morpho-anatomical changes in prunus rootstocks under root hypoxia. the figure summarizes the effect of aox and cytc on no and ros generation. regarding ros, the early induction of aox ( h) and the late induction of cytc ( and h) would lead to a regulation of ros accumulation in a temporally non-exclusive way in the root-hypoxia-tolerant prunus rootstock (‘mariana m ’). thus, at the beginning of stress by o deficiency, this genotype would be preventing the accumulation of ros in roots, but as stress progresses, in the context of apoptosis, the elevation of ros levels has been associated with the activity of cytc [ , ]. the generation of aerenchyma mediated by apoptosis present in the original root system, and the generation of adventitious roots with aerenchyma and hypertrophied lenticels, are characteristic features of ‘mariana m ’. these traits are completely absent in the root-hypoxia-sensitive prunus rootstock (‘mazzard f / ’). the generation of air-filled spaces results in an avoidance strategy in relation to o deprivation, which is associated with the maintenance of an adequate metabolism and energy supply at the whole plant level. the blue and red arrows represent the over- and down-expression of genes related to metc. aox, alternative oxidase; cytc, cytochrome c; rcf , respiratory supercomplex factor ; cytbo , cytochrome bo ubiquinol oxidase; cytbc (sub ), cytochrome bc complex subunit ; cytb red, cytochrome b reductase; cox(sub b ), cytochrome c oxidase subunit b ; cox(sub b ), cytochrome c oxidase subunit b ; [no], nitric oxide; [ros], reactive oxygen species. images of morpho-anatomical changes were obtained from [ , ]. this figure was created using biorender. plants , , of . conclusions and perspectives in fruit trees research the effects of oxygen deficiency and the adaptive responses of plants have been extensively studied in herbaceous species, mainly with annual life cycles. however, woody fruit tree species, of great economic importance in temperate and sub-tropical zones, have been poorly attended. from a physiological point of view, characterizing the adjustment of photosynthesis to hypoxic conditions is a useful approach to contribute to the definition of the tolerance of these species to such environmental stress. thus, species more tolerant to root hypoxia, capable of maintaining higher levels of photosynthetic activity, may provide greater carbohydrate reserves for facing the energy crisis triggered by anaerobiosis. on the other hand, transcriptomic studies have become useful for getting a broader view of the metabolic adaptation of fruit trees to hypoxia. furthermore, together with evaluating the classically described metabolic pathways for plants under hypoxia, transcriptomic analyses allow the investigation of routes or processes less explored in these perennial plant species, such as the genetic determinants of energy sensing or the genes involved in the metc. in this review, we focused on analyzing the physiological and molecular aspects of the responses of fruit trees under root hypoxia, with emphasis on a study model that involves two genotypes of prunus rootstocks with contrasting tolerances to o deficiency. in light of the multiple and diverse antecedents evaluated, it seems clear that the tolerant species of fruit trees manage to adapt and survive waterlogging or flooding due to their ability to detect oxygen deficiency more quickly and change their metabolism through a suitable transcriptomic reprogramming. in this sense, keeping calm, and avoiding the activation of more routes than those that are strictly necessary or less energy efficient in an anaerobic environment, would allow the plant to invest its energy budget precisely, without exhausting it. this would be exemplified by the measured amount of degs detected in the root-hypoxia-tolerant prunus rootstock versus the massive transcriptomic reconfiguration evidenced in the sensitive genotype ‘mazzard f / ’, implying a higher energy expenditure for the latter. at the same time, the anatomical and biochemical factors that operate in favor of maintenance processes, which are less energy demanding than those of repair, contribute to the early adaptation to root hypoxia of the tolerant genotype. subsequently, late morpho-anatomical modifications end up defining a hypoxia-avoidance strategy that allows long-term survival in tolerant genotypes. finally, further studies are needed into the effects that re-oxygenation exerts on the fruit trees during the hypoxia recovery phase. in addition, a rising challenge in the study of the adaptive response to root hypoxia of woody fruit trees would involve epigenetic approaches oriented towards analyzing the phenomena of the memory of stress that can be transmitted between rootstocks and scion, or between growing seasons, and how it affects the yielding behavior of the orchards. author contributions: conceptualization, a.s. and p.p.; transcriptomic data re-analysis, p.m.; writing—original draft preparation, a.s., g.t., i.o., m.o. and p.p.; writing—review and editing, a.s., g.t. and p.p.; visualization, a.s., g.t. and p.p.; supervision, a.s. and p.p.; funding acquisition, a.s., g.t., m.o. and p.p. all authors have read and agreed to the published version of the manuscript. funding: this research was funded by agencia nacional de investigacion y desarrollo (anid), grant number r a and fondo nacional de desarrollo cientÍfico y tecnolÓgico (fondecyt), grant number . acknowledgments: we thanks to all ceaf colleagues who have contributed from different areas with their research on root hypoxia and whose work has been part of this review. conflicts of interest: the authors declare no conflict of interest. references . loreti, e.; perata, p. the many facets of hypoxia in plants. plants , , . 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[crossref] [pubmed] © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . /j. - . .tb .x http://dx.doi.org/ . /s - - - http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /pp. . http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /jbc.m . http://dx.doi.org/ . /j.semcdb. . . http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /mcb. - http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /s - - -x http://dx.doi.org/ . /fpls. . http://dx.doi.org/ . /aob/mcf http://dx.doi.org/ . /j. - . . .x http://dx.doi.org/ . /oeco. . . http://dx.doi.org/ . /annals. . http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /pp. . http://www.ncbi.nlm.nih.gov/pubmed/ http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	introduction 	edaphic conditions that promote o deficiency 	fruit tree responses to o deficiency 	physiological and biochemical response of fruit trees under o deficiency 	morpho-anatomical changes in fruit trees under o deficiency 	transcriptomic reprogramming of principal pathways involved in energy metabolism under o deficiency 	root respiration under o deficiency 	conclusions and perspectives in fruit trees research 	references review: the republican reversal: conservatives and the environment from nixon to trump by james morton turner and andrew c. isenberg | pacific historical review | university of california press skip to main content close 	ucpress 	about us 	blog 	support us 	contact us search search input search input auto suggest search filter all content pacific historical review search user tools register carnegie mellon university carnegie mellon university sign in toggle menumenu 	 content 	 recent content 	 browse issues 	 all content 	 purchase 	 alerts 	 submit 	 info for 	 authors 	 librarians 	 info for advertisers 	 reprints & permissions 	 about 	 journal 	 editorial team 	 contact us skip nav destination article navigation close mobile search navigation article navigation volume , issue fall 	 previous article 	 next article article navigation book review| november review: the republican reversal: conservatives and the environment from nixon to trump by james morton turner and andrew c. isenberg the republican reversal: conservatives and the environment from nixon to trump . by james morton turner and andrew c. isenberg. (cambridge :  harvard university press ,   . x + .) j. brooks flippen j. brooks flippen southeastern oklahoma state university search for other works by this author on: this site pubmed google scholar pacific historical review ( ) ( ): – . https://doi.org/ . /phr. . . . 	 split-screen 	 views icon views 	article contents 	figures & tables 	video 	audio 	supplementary data 	 pdf linkpdf 	 share icon share 	facebook 	twitter 	linkedin 	email 	 guest access 	 tools icon tools 	 get permissions 	 cite icon cite 	 search site citation j. brooks flippen; review: the republican reversal: conservatives and the environment from nixon to trump by james morton turner and andrew c. isenberg. pacific historical review november ; ( ): – . doi: https://doi.org/ . /phr. . . . download citation file: 	ris (zotero) 	reference manager 	easybib 	bookends 	mendeley 	papers 	endnote 	refworks 	bibtex toolbar search search search input search input auto suggest search filter all content pacific historical review search this content is only available via pdf. © by the pacific coast branch, american historical association article pdf first page preview close modal send email recipient(s) will receive an email with a link to 'review: the republican reversal: conservatives and the environment from nixon to trump by james morton turner and andrew c. isenberg' and will not need an account to access the content. *your name: *your email address: cc: *recipient : recipient : recipient : recipient : recipient : subject: review: the republican reversal: conservatives and the environment from nixon to trump by james morton turner and andrew c. isenberg optional message: (optional message may have a maximum of characters.) submit × citing articles via google scholar crossref 	 latest 	 most read 	 most cited emerging nations, emerging empires: inter-imperial intimacies and competing settler colonialisms in hawai‘i pilgrims’ progress: “efficient america,” “spiritual india,” and america’s 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simplice asongu asongusimplice@yahoo.com african governance and development institute, p. o. box , yaoundé, cameroon ghassen el montasser g.elmontasser@gmail.com department of quantitative methods, École supérieure de commerce de tunis, university of manouba, manouba, tunisia hassen toumi toumihass@gmail.com faculty of economics and management|, university of sfax, street of airport, km . , lp , sfax , tunisia mailto:asongusimplice@yahoo.com mailto:g.elmontasser@gmail.com mailto:toumihass@gmail.com © african governance and development institute wp/ / agdi working paper research department simplice a. asongu, ghassen el montasser & hassen toumi september abstract this study complements existing literature by examining the nexus between energy consumption (ec), co emissions (ce) and economic growth (gdp) in african countries using a panel ardl approach. the following findings are established. first, there is a long run relationship between ec, ce and gdp. second, a long term effect from ce to gdp and ec is apparent, with reciprocal paths. third, the error correction mechanisms are consistently stable. however, in cases of disequilibrium only ec can be significantly adjusted to its long run relationship. fourth, there is a long-run causality running from gdp and ce to ec. fifth, we find causality running from either ce or both ce and ec to gdp and inverse causal paths are observable. causality from ec to gdp is not strong, which supports the conservative hypothesis. sixth, the causal direction from ec to gdp remains unobservable in the short term. by contrast, the opposite path is observable. there are also no short-run causalities from gdp, or ec, or ec and gdp to ec. policy implications are discussed. jel classification: c ; o ; o ; q : q keywords: energy consumption; co emissions; economic growth; africa . introduction with the transition for millennium development goals (mdgs) to sustainable development goals (sdgs), the literature on nexuses between energy, growth and pollution continue to be of significant interest in academic and policy-making circles. the relevance of energy as an engine of economic prosperity has been substantially documented (ozturk, ). however, the efficient exploration, exploitation and development of energy within a country or region are crucial for the wellbeing of individuals, optimal usage of public commodities, inclusive growth and sustainable development (apkan, ). to the best our knowledge, the highlighted concerns are most relevant for africa’s contemporary development for at least a fivefold reason, notably: dismal poverty trends, high economic growth, energy crisis, poor energy management and consequences of climate change. first, the april world bank report has revealed that poverty has been decreasing in all regions of the world with the exception of africa where % of countries in sub-saharan africa (ssa) are substantially off-track from achieving the mdgs poverty target (asongu and kodila-tedika, ). second, the continent has enjoyed over two decades of growth resurgence (fosu, ) and is currently host to seven of the ten fastest growing economies of the world (asongu and rangan, ). third, one of the most important challenges the continent would be confronted with in the post- development agenda is energy crisis (akinyemi et al., ). to put this into more perspective, according to shurig ( ), statistics from the international energy agency (iea) suggest only % of ssa has access to energy. moreover: (i) electricity consumption per capita in the sub-region is one- sixth of the world’s average and (ii) the total consumption across the region can be compared to that of the new york state. fourth, the inefficient management of the underlying energy crisis in many african countries has been cause for alarm (anyangwe, ). in most of these countries (e.g nigeria), pressure on electricity demand has promoted a high demand for substitute fossil fuels that are subsidized by government to the detriment of renewable energy. it is therefore not surprising that many households on the continent’s most populated country are overly relying on the burning of petroleum fuels for self-generated electricity (apkan, ). fifth, unsustainable fossil fuel consumption has been substantially documented as one of the main causes of global warming (huxster et al., ). moreover, africa would be the hardest hit by the consequences of climate change (kifle, ). in essence, emissions of carbon dioxide (co ) account for more than % of world greenhouse gas emissions, of which approximately % of it is produced by the energy sector (akpan, ). as far as we have reviewed, there are two main strands in the literature on nexuses between economic growth, environmental pollution and energy. the first stream which is concerned with the relationship between economic growth and environmental pollution has most notably focused on investigating the validity of an environmental kuznets curve (ekc) assumption. the ekc hypothesis postulates that in the long run, there is an inverted u-shaped nexus between per capita income and environmental degradation. some examples of studies in this strand include: akbostanci et al. ( ), diao, et al. ( ) and he and richard ( ). the second strand entails two streams of literature: the nexus between the consumption of energy and economic growth on the one hand and on the other hand, the relationship between economic growth, energy and pollution. whereas the former stream is well documented in the literature (mehrara, ; esso, ) , the latter stream within a multivariate setting is a relatively new research area. the studies within multivariate frameworks have produced very conflicting results in both developed and developing countries (jumbe, ; ang, ; apergis and payne, ; menyah and wolde-rufael, ; ozturk and acaravci, ; bölük and mehmet, ; begum et al., ). a common denominator to above strands is that the interesting literature has been particularly skewed towards developed nations and the emerging economies of asia and latin america (see ozturk, ), with very scarce focus on african countries. the scarce literature on africa can be engaged in two main strands, notably: country-specific and multi-country studies. the following studies are note worthy in the first strand. first, belloumi ( ) has examined the relationship between energy consumption and economic growth in tunisia for the period - using granger causality and vector error correction model (vecm) to establish long-run bidirectional causality. second, odhiambo ( a) has focused on south africa using granger causality for the period to to establish that electricity consumption leads to growth. third, in another study, odhiambo ( b) targets tanzania using the same periodicity with the autoregressive distributed lag (ardl) bounds testing approach to conclude on bidirectional causality between economic growth and electricity consumption. fourth, akinlo ( ) position an inquiry on nigeria for the period to also see olusegun ( ) and akinlo ( ). using johansen–juselius, co-integration and vecm approaches to find that electricity consumption causes economic growth. fifth, zhang et al. ( ) employ a log mean divisia index (lmdi) method to assess the contribution of factors that affect co emission related to energy in south africa for the period - . the authors establish that: (i) the intensity of energy play an important role in mitigating co emission, followed by effects from fossil and renewable energy structures and (ii) economic activity is critical to energy-related co emission. sixth, using the ardl bounds testing for cointegration and the vecm granger causality approaches, ben jebli and ben youssef ( ) have recently investigated the nexus between per capita co emissions, gross domestic product (gdp), renewable and non-renewable energy consumption in tunisia for the period - . the findings show short-run unidirectional causality flowing from gdp, non-renewable energy and co emissions to renewal energy while the inverted u-shaped ekc hypothesis is neither verified analytically nor graphically in the long-run. the second strand on multi-country lines of inquiry can be summarised with the following studies. first, wolde-rufael ( ) has examined african nations for the period - using the toda–yamamoto’s granger causality to establish the following: (i) growth causes energy consumption in algeria, the democratic republic of congo, ghana, egypt and côte d’ivoire; (ii) energy consumption causes growth in cameroon, nigeria and morocco; (iii) there is a bidirectional causality in gabon and zambia and (iv) no causality in benin, the congo republic, senegal, south africa, sudan, togo, tunisia and zimbabwe. second, in a latter study, wolde-rufael ( ) has examined linkages between electricity consumption and economic growth in african economies from to , to conclude that: (i) economic growth leads to electricity consumption in zimbabwe, zambia, senegal, cameroon, nigeria and ghana; (ii) the opposite flow of causality in tunisia, the democratic republic of congo and benin; (iii) bidirectional causality in morocco, gabon and egypt and (iv) no causality evidence in sudan, south africa, kenya, algeria and the congo republic. third, akinlo ( ) investigates the relationship between economic growth and energy consumption in african countries using an ardl bound test to establish two main findings: (i) economic growth causes energy consumption in senegal, congo, zimbabwe, sudan, ghana and gambia while (ii) there is no evidence of causality in togo, kenya, nigeria, cameroon and côte d’ivoire. fourth, ozturk and bilgili ( ) examine the long run dynamics of biomass consumption and economic growth using dynamic panel analyses in ssa countries for the period - to conclude that biomass consumption is affected by economic growth. fifth, using linear and hidden cointegration methodologies, tiwari et al. ( ) examine whether asymmetric effects exist between energy (renewable and non- renewable) production and economic growth in ssa for the - period. the empirical findings confirm and reject the growth hypothesis for some sub-samples, implying that conservation policies could adversely affect growth. sixth, ackah and kizys ( ) investigate the determinants of renewable energy in africa using fixed effects, random effects and dynamic panel models to find that the principal drivers of renewable energy in oil-rich african economies are: energy resource depletion per capita, real income per capita, energy prices and carbon emissions per capita. seventh, raheem and yusuf ( ) use african countries for the period - within the framework of a nonlinear model to find evidence of the ekc hypothesis from the energy-growth nexus in tunisia, togo, egypt, côte d’ivoire and benin. moreover: (i) high regime of energy consumption boosts growth in senegal, morocco and algeria; (ii) low regime of energy consumption slows growth in south africa and sudan whereas (iii) evidence of a neutrality hypothesis is established for zambia and cameroon. noticeably, the above literature leaves room for improvement in two key areas, notably, the need to: (i) go beyond the scope of country-specific analysis and engage panel studies which have broader policy implications and (ii) position lines of inquiry within a trivariate analytical framework. accordingly, with increasing calls for more economic integration in africa within policy and academic circles (akpan, ; tumwebaze and ijjo, ; shuaibu, ), results on underlying issues that are relevant to a broad set of countries are more likely to enhance the harmonization of common policies in the post- sustainable development agenda. moreover, a trivariate analytical framework intuitively has more policy rewards. in light of the above, this study aims to test the nexus between energy consumption, co emissions and economic growth in african countries using a panel ardl approach. the rest of the paper is structured as follows. section discusses the data and methodology. the empirical analysis, presentation of results and discussion of findings are covered in section . section concludes with implications and future research directions. . data and methodology . data the variables used in this study are gdp per capita measured in constant us$, energy consumption (ec) measured in kg of oil equivalent per capita, and co emissions measured in metric tons per capita. these variables are obtained from the world development indicators (wdi, ). the data are annual and spanning from to . this is the common period resulting from the intersection of three time spans of our variables. the countries included in this study are: angola, benin, botswana, cote d’ivoire, cameroon, congo republic, algeria, egypt, ethiopia, gabon, ghana, kenya, morocco, mozambique, nigeria, sudan, senegal, togo, tunisia, tanzania, south africa, the democratic republic of the congo, zambia, and zimbabwe. . methodology pesaran et al. ( ) have introduced the pooled mean group (pmg) approach in the panel ardl framework. according pesaran et al. ( ), the homogeneity in the long run relationship can be attributed to several factors such as: arbitration condition, common technologies, or the institutional development which was covered by all groups. in our analysis framework, this homogeneity may be the consequence of the remote objective of reducing energy consumption by promoting alternative sources, including renewable energies. furthermore, and in environmental policy, the inclusion of deforestation in the united nations framework convention on climate change (unfccc), as the major source of reducing co emissions, confirms that the structuring process of an international regime on forests is now set up, especially in tropical african countries ( ongolo and karsenty ( )). the panel ardl method had been used by binder & offermanns ( ) for the purchasing power parity analysis in europe, by bildirici and kayıkci ( ) for analysing the relationship between electricity consumption and economic growth and boubaker and jouini ( ), who used this method in the finance area. in lines with the pesaran et al.’ ( ) methodology, the ardl model, including the long-run relationship between variables, may follow as: ( ) ( ) ( ) where gdp, ec, and ce are, respectively, the logarithms of the gross domestic product per capita, the energy consumption and the co emission. and (k= , , ) are the first difference operator and a white noise term. also, denotes in ( ), ( ), and ( ), a country specific intercept. thereupon, the subscript i denotes a specific unit and is varying from to n. in order to choose the optimal lag length for each variable, we will proceed to a grid search based on the minimization of the schwarz information criterion (sbic). a reasonable generalization of cointegration test pesaran et al. ( ) from time series to panel data may formulate the null hypothesis of no co-integration between the three variables in eq. ( ) as follows: against the alternative hypothesis likewise, the null hypothesis of no co-integration between the three variables may be written as however, in eq. ( ), the null hypothesis of no co-integration between the three variables may be formulated as even though the generalization of this test is possible in this way, we have not yet encountered in the literature the determination of its critical values in panel data context. logically, when we have ‘large’ values of the fisher statistics, associated with the above tests, we reject the no-cointegration null hypothesis. it is for this reason that the majority of works, resorting to the panel ardl approach, have made use of the cointegration test of pedroni ( ) given that the tests with null hypotheses presented above were not well specified in applied works. in the second step, if the null hypothesis of co-integration is not rejected, we estimate the long run relationship between the three variables. for example, this long run relationship for the first ardl model described by eq. ( ) is written as follows: ( ) in doing so, we have respected the assumption imposed by the pmg approach, namely the coefficients of the long run relationship are the same for each country. moreover, this assumption has been also respected in the specification of the no co-integration null hypotheses associated with the three above-described ardl models. likewise, the long-run relationships corresponding to the two remaining ardl models are established in the same way. the error correction terms are derived accordingly from these relationships, and they will be used in the following. next, the error correction models, used to consider the short run relationships between the variables, are constructed as follows: ( ) ( ) ( ) where the residual (k= , , ) is independently and normally distributed with zero mean and constant variance, and is the error correction term defined from the long-run equilibrium relationship. the parameters a, b and c indicate the speed of adjustment to the equilibrium level. as mentioned above, the estimators of all these parameters are obtained by having recourse to the pmg method. more specifically, following pesaran et al. ( ), the parameters of each error correction model are estimated using the nonlinear algorithm of newton-raphson. the pmg estimators obtained are consequently consistent and asymptotically distributed normally, according to pesaran et al. ( ). moreover, they are intermediate estimators involving both pooling and averaging. inasmuch as the pmg approach allows short-term dynamic specifications which differ from country to country while long-term coefficients are constrained to be the same, it has some advantages compared to the dynamic ols (dols) and fully modified ols (fmols) methods. note that we do not include any control variables in the three specifications of the ardl models following pesaran and smith ( ), who reason in support of parsimonious models when the object of interest is not the impact "ceteris paribus" of an explanatory variable. in the last stage, the granger causality tests are used in three ways following bildirici and kayikçi ( ). first, short run causalities are tested by considering for all i and if we focus, for example, on testing in ( ) the short run causality running from ec to gdp. the other short run causality directions follow in the same way in ( ), ( ) and ( ). second, long run causalities are tested from the ects in those equations. more specifically, the corresponding null hypotheses are , and . finally, if we focus on the strong causality running, in ( ), from ec to gdp, the null hypothesis is for all i and in the same way, the null hypotheses are specified for testing the other strong causality directions in ( ), ( ) and ( ). for further details, see bildirici and kayikçi ( ). . empirical results . unit root tests to test the stationarity of the data, we used a variety of panel unit root tests. particularly, we have used the tests of: levin, lin and chu ( ) [henceforth llc], im, pesaran and shin ( ) [henceforth ips], breitung ( ) and hadri ( ). all these tests are considered first generation panel unit root tests because they assumed the independence between cross section units. the ips test had the objective of rectifying the restrictive llc hypothesis, namely the homogeneous nature of the autoregressive root under the alternative hypothesis. on the other hand, breitung ( ) suggested a statistic without a bias adjustment to avoid the dramatic loss of power, observed for the llc and ips tests if individual-specific trends are included. we still have to mention the null hypothesis of hadri’s ( ) test is stationarity. in contrast, the null hypotheses of the other tests are the unit root ones. the use of both types of tests can be advantageous to avoid the loss a power noted when each cross section alternative is near the unit root. finally, we chose from the second generation tests, that of choi ( ). in particular, we used the z and the modified fisher statistics. from tables and , we can conclude that gdp and ec are integrated variables , while the variable ce is stationary, so that we could use the panel ardl model. this finding is deduced from the conclusions drawn from the majority of panel unit root tests. table : panel unit root results: series in level gdp ec ce intercept trend intercept trend intercept trend llc . ( . ) . ( . ) . ( . ) - . ( . ) - . ( . ) - . ( . ) ips . ( . ) . ( . ) . ( . ) . ( . ) - . ( . ) - . ( . ) breitung -------------- . ( . ) ------------- . ( . ) ------------- . ( . ) hadri . ( . ) . ( . ) . ( . ) . ( . ) . ( . ) . ( . ) choi:z statistic . ( . ) . ( . ) . ( . ) . ( . ) . ( . )) - . ( . ) choi: fisher . ( . ) . ( . ) . ( . ) . ( . ) - . ( . ) . ( . ) notes: table show the statistics of the panel unit root tests. the values in brackets are the corresponding p values. table : panel unit root test results: series in first difference ∆gdp ∆ec ∆ce intercept trend intercept trend intercept trend llc - . ( . ) - . ( . ) - . ( . ) - . ( . ) - . ( . ) - . ( . ) ips - . ( . ) - . ( . ) - . ( . ) - . ( . ) - . ( . ) - . ( . ) breitung ------------ - . ( . ) ------------- - . ( . ) ------------ - . ( . ) hadri . ( . ) . ( . ) . ( . ) . ( . ) . ( . ) . ( . ) choi:z statistic - . ( . ) - . ( . ) - . ( . ) - . ( . ) - . ( . ) - . ( . ) choi: fisher . ( . ) . ( . ) . ( . ) . ( . ) . ( . ) . ( . ) notes: table show the statistics of the panel unit root tests. the values in brackets are the corresponding p values. . cointegration resuts table reports the results of pedroni’s ( ) cointegration test. we have only three statistics, from seven, indicating the rejection of the no cointegration null hypothesis. within this set of the three statics, we find the panel adf and group adf statistics, considered as the more reliable statistics by pedroni ( ). in our results, the null hypothesis of no cointegration is rejected at % level and % level by the panel-adf statistic while the group-adf statistic rejects this null hypothesis at % level. therefore, we can conclude that there is a long run relationship between energy consumption, co emissions and gdp in our african countries. the evidence on cointegration is consistent with country-specific and multi-country studies engaged in the literature, notably in: tunisia (belloumi, ), south africa (odhiambo, a), tanzania (odhiambo, b) and akinlo ( ). whereas these studies have employed the vecm for the most part, what is apparent is that the underlying methodology is contingent on the presence of cointegration. while findings of underlying studies may not be directly comparable with the present line of inquiry, owing to differences in data structure, what is quite apparent as common denominator among them is the presence of a long-run equilibrium between energy consumption, co emissions and gdp. we may therefore reasonably infer that the documented country-specific evidence of cointegration may well be extended to regional and continental levels for broader policy implications. table : results of pedroni’s ( ) cointegration test statistics probabilities panel v-statistic - . . panel rho-statistic . . panel pp-statistic - . . panel adf-statistic - . ** . group rho-statistic . . group pp-statistic - . * . group adf-statistic - . *** . notes: *** , ** and * imply significance levels at the %, % and % levels, respectively. . panel ardl results . . pmg long-run estimates we can deduce from table that there is great evidence that the variable ce has long run effects on gdp and ec. note that the reciprocal paths of these long-run effects are observed with as much evidence. however, the long-run effects of ec on gdp (and vice versa) are only significant at the % level. table : pmg long run estimates dependent variable gdp ec ce independent variable gdp ----------------- - . * (- . ) . *** ( . ) ec - . * (- . ) ----------------- . *** ( . ) ce . *** ( . ) . *** ( . ) ---------------- notes: the values in parentheses are the standard errors. *** and * indicate significance levels % and %, respectively. . . pmg short-run estimates this section presents short-run estimates and describes the error correction model corresponding to the established cointegration relationships or long-run equilibriums. while at equilibrium the error correction term (ect) is zero, a non-zero ect implies that pairs of linkages have deviated from the long-term equilibrium. hence, the ect helps in the adjustment and partial restoration of the cointegration relationship. the underlying restoration of the equilibrium requires that the ect: (i) has an expected sign and (ii) is within the right interval. in essence, a negative ect within the interval of and is necessary for a stable error correction mechanism (asongu, ab). a positive ect denotes deviation from the equilibrium. it follows that a negative ect sign is necessary for the restoration of equilibrium following an exogenous shock. in the determination of the speed with which the equilibrium is restored, indicates no adjustment whereas one period later, suggests full adjustment. tables , and present the feedback coefficients for the cointegrating vectors for respectively gdp, ec and ce. we first notice that irrespective of tables, the signs and intervals of ects are consistent with theory, though only the ect corresponding to ec is significant. this implies that in the presence of a shock, only ec can significantly be restored to its long-run equilibrium. this is an unfortunate scenario because the fundamentals of all ects are not weakly exogenous, with slight exceptions from ‘∆ (ec(- ))’, ‘∆ (gdp(- )) and ∆ (ce(- ))’ and ‘∆ (gdp(- ))’ in table , table and table respectively. to put this technical insight into more perspective, adjustment of imbalances (i.e deviations from equilibrium) to restore a cointegration or a long-term relationship depends on fundamentals of error correction terms (ects). the highlighted fundamentals or lagged variables are not significant; thus display weak exogeneity relative to corresponding ects. hence they do not significantly contribute to adjusting underlying imbalances (or deviations) to corresponding cointegration relationships. table : pmg short-run estimate, ∆gdp is the dependent variable estimate t-student p-value constant . *** . . ∆ (gdp(- )) . *** . . ∆ (ce(- )) . *** . . ∆ (ce) . ** . . ∆ (ec(- )) - . - . . ∆ (ec) . *** . . ect (- ) - . - . . notes: the values in parentheses are the standard errors. *** and ** indicate significance levels % and %, respectively. gdp: gross domestic product. ec: energy consumption. ce: co emissions. gdp (- ) refers to . ∆ ( ) is the first difference operator. table : pmg short-run estimate, ∆ec is the dependent variable estimate t-student pvalue constant . ** . . ∆ (ec(- )) - . * - . . ∆ (gdp) . *** . . ∆ (gdp(- )) . . . ∆ (ce) . *** . . ∆ (ce(- )) - . - . . ect (- ) - . *** - . . note: *** , ** and * indicate significance levels %, % and %, respectively. gdp: gross domestic product. ec: energy consumption. ce: co emissions. table : pmg short-run estimate, ∆ce is the dependent variable estimate t-student pvalue constant - . - . . ∆ (ce(- )) - . *** - . . ∆ (ce(- )) - . *** - . . ∆ (gdp) . ** . . ∆ (gdp(- )) . . . ∆ (gdp(- )) - . *** - . . ∆ (ec) . *** . . ∆ (ec(- )) . *** . . ∆ (ec(- )) . *** . . ect(- ) - . - . . notes: the values in parentheses are the standard errors. *** and ** indicate significance levels % and %, respectively. gdp: gross domestic product. ec: energy consumption. ce: co emissions. gdp (- ) refers to . ∆ ( ) is the first difference operator. . causality tests we have resorted to the wald statistics, besides the f ones, in doing the causality tests. indeed, the usual t- and f-statistics are still valid in the context of non-linear estimation, but they are no flexible enough; see brooks ( ). this is all the more reason why we have added the wald statistics. . . long run causalities in view of table , we can conclude that there is only one long-run causality running from gdp and ce to ec. two insights may result from this finding. ce and ec may not be causing gdp in the long-term because: (i) ec is low owing to relative low access to energy and (ii) ce emissions are associated with activities of subsistence (e.g farming) instead of mainstream industrial or mechanized farming processes. this is broadly consistent with the conservative hypothesis which we engage to elaborate detail in the next section. table : long-run causality statistics statistics wald p-value fisher p-value dependent variable gdp . . . . ec . *** . . *** . ce . . . . notes: *** indicates a significant long-run causality statistic at the % level. gdp: gross domestic product. ec: energy consumption. ce: co emissions. . . strong causalities we can conclude from table that there is great evidence of a strong causality running from either ce or both of ce and ec to gdp. note that the inverse causal paths are also observable. it is not surprising that there is no strong causality from energy consumption to gdp for the whole considered panel. this supports the conservative hypothesis which assumes a unidirectional causality running from economic growth to energy consumption. accordingly, the conservative hypothesis is in favor of the fact that energy conservation policies may have little or no impact on economic growth. the established evidence of growth leading to energy consumption is broadly consistent with some studies in the literature that have found similar outcomes, notably: (i) ben jebli and ben youssef ( ) in tunisia within the framework of renewable energy; (ii) wolde-rufael ( ) in african countries in the perspective of electricity consumption; (iii) akinlo ( ) with regard to energy consumption in senegal, congo, zimbabwe, sudan, ghana and gambia; (iv) ozturk and bilgili ( ) within the framework of biomass consumption in african countries and (v) ackah and kizys ( ) who have recently shown that gdp per capita is a main driver of energy consumption in oil-rich african countries. conversely, there is also evidence against the established hypothesis in the engaged literature. such is apparent in studies that have found that energy consumption causes growth. these include: (i) wolde-rufael ( ) in cameroon, nigeria and morroco; (ii) wolde- rufael ( ) for tunisia, the democratic republic of congo and benin and (iii) raheem and yusuf ( ) with senegal, morocco and algeria. while the findings may be conflicting based on country-specific studies, the interest of using a panel data structure somehow helps to provide a broad or more general view. hence, from a panel perspective, we might reasonably infer that the conservative hypothesis is broadly relevant. this is logical because african economies are not based on industrial activities. table : strong causalities statistics causality directions wald p-value fisher p-value ec gdp . . . . ce gdp . *** . . *** . ec,ce gdp . *** . . *** . gdp ec . *** . . *** . ce ec . *** . . *** . ce,gdp ec . *** . . *** . gdp ce . ** . . ** . ec ce . *** . . *** . gdp,ec ce . *** . . *** . notes : *** and ** imply significance levels at the % and % levels, respectively. ‘ ’ refers to the direction of causality. gdp: gross domestic product. ec: energy consumption. ce: co emissions. . . short-run causalities the causal direction from ec to gdp remains unobservable in the short term. by contrast, the opposite path is observable. there are also no short-run causalities from gdp, or ce or ce and gdp to ec. based on the findings, we can neither confirm nor reject the conservative hypothesis because whereas ec does not significantly cause gdp, the reverse path is not also significantly apparent. this scenario is broadly in accordance with engaged studies that have established evidence of no causality, especially within the framework of short-run granger causality, namely: (i) wolde-rufael ( ) for south africa, kenya, algeria and the congo republic from the angle of electricity consumption; (ii) akinlo ( ) on the absence of causality evidence in togo, kenya, nigeria, cameroon and côte d’ivoire and (iii) raheem and yusuf ( ) on the confirmation of a neutrality hypothesis established for zambia and cameroon. table : short-run causalities statistics causality directions wald p-value fisher p-value ec gdp . . . . ce gdp . *** . . *** . ec,ce gdp . ** . . ** . gdp ec . . . . ce ec . . . . ce,gdp ec . . . . gdp ce . ** . . ** . ec ce . *** . . *** . gdp,ec ce . *** . . *** . notes : *** and ** imply significance levels at the % and % levels, respectively. ‘ ’ refers to the direction of causality. gdp: gross domestic product. ec: energy consumption. ce: co emissions. . concluding implications and further directions the study has complemented existing literature in two key areas, notably the need to: (i) engage panel studies by positioning lines of inquiry beyond the scope of country-specific literature and (ii) steer clear of substantially documented bivariate studies by modeling within a trivariate framework. to these ends, we have investigated the nexus between energy consumption (ec), co emissions (ce) and economic growth (gdp) in african countries using a panel ardl approach. the following findings have been established. first, there is a long run relationship between ec, ce and gdp. second, a long term effect from ce to gdp and ec is apparent, with reciprocal paths. third, the error correction mechanisms are consistently stable. however, in cases of disequilibrium only ec can be significantly adjusted to its long run relationship. fourth, there is a long-run causality running from gdp and ce to ec. fifth, we find causality running from either ce or both ce and ec to gdp and inverse causal paths are observable. causality from ec to gdp is not strong, which supports the conservative hypothesis. sixth, the causal direction from ec to gdp remains unobservable in the short term. likewise, the opposite path isn’t observable in the short term. there are also no short-run causalities from gdp, or ce or ce and gdp to ec. policy implications can be discussed along three main strands, notably on the: long- run relationships, feedbacks to restore the long term relationships in event of disequilibrium and the unsurprising absence of causality flowing from ec to gdp. first, the long run linkages imply that it would require policy to carefully tailor ec, ce and gdp in the post- development agenda. however, the nexuses would have to be tailored so that, inter alia: (i) gdp is not compromised by ce, (ii) the responsiveness of ce to gdp is maintained at minimum, which would require, (iii) more dependence on renewable ec and less dependence on fossil fuels that are the main drivers of ce. second, the evidence that in the presence of disequilibrium only ec can be significantly adjusted to restore the long term relationship implies the fundamentals of ects corresponding to gdp and ce need to be consolidated. third, the unsurprising finding of no strong causality flowing from ec to gdp has at least a twofold implication, notably: (i) confirmation of the conservative hypothesis which we have engaged substantially in the preceding sections and (ii) an articulation of the energy crisis that most of the sampled countries are facing. the overall implication is that, african countries can substantially increase current gdp growth rates if access to energy is improved, especially (renewable energy). the overwhelming evidence of causality flowing from one variable to another may not be exhaustive for drawing economic inferences. the scale and timing of shocks from one variable on the one hand and responses to shocks by corresponding variables on the other hand, may be required for more policy options. it would be interesting if further research devoted to improving the extant literature moves towards these directions. references ackah, i. and r. kizys ( ). “green growth in oil producing african countries: a panel data analysis of renewable energy demand”, renewable and sustainable energy reviews, (october), pp. - . akbostanci, e., s. turut-asi, and g.i. tunc ( ). “the relationship between income and environment in turkey: is there an environmental kuznets curve?”, energy policy, , pp. - . akinlo, a. e. 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( ). “electricity consumption and economic growth: a time series experience for african countries”. energy policy, ( ), pp. – . zhang, m., s. dai, and y. song ( ). “decomposition analysis of energy-related co emissions in south africa”, journal of energy in south africa, ( ), pp. - . http://www.theguardian.com/global-development-professionals-network/ /jun/ /renewable-energy-electricty-africa-policy http://www.theguardian.com/global-development-professionals-network/ /jun/ /renewable-energy-electricty-africa-policy microsoft word - entropy- - .docx entropy , , - ; doi: . /e entropy issn - www.mdpi.com/journal/entropy article entropy harvesting edward bormashenko ariel university, physics faculty, p.o.b. , ariel , israel; e-mail: edward@ariel.ac.il; tel.: + - - - ; fax: + - - - . received: february ; in revised form: may / accepted: may / published: june abstract: the paper introduces the notion of “entropy harvesting” in physical and biological systems. various physical and natural systems demonstrate the ability to decrease entropy under external stimuli. these systems, including stretched synthetic polymers, muscles, osmotic membranes and suspensions containing small hydrophobic particles, are called “entropic harvesters”. entropic force acting in these systems increases with temperature. harvested entropy may be released as mechanical work. the efficiency of entropy harvesting increases when the temperature is decreased. natural and artificial energy harvesters are presented. gravity as an entropic effect is discussed. keywords: entropy harvesting; entropic force; gravity; natural energy harvesters . introduction the concept of energy harvesting has attracted widespread attention in the scientific and engineering communities [ – ]. energy scavenging devices are designed to capture ambient energy and convert it into usable electrical energy. the concept of power harvesting works towards developing self-powered devices that do not require replaceable power supplies. a number of sources of harvestable ambient energy exist, including waste heat, vibration, electromagnetic waves, wind, flowing water, and solar energy [ – ]. our paper introduces the concept of “entropy harvesting” in its relation to real physical systems. the notion of “entropy harvesting” has been already introduced in the fields of communication security, cryptography and data processing [ – ]. in our paper we revisit the idea of entropy harvesting, and implement it in physical systems, where entropy decreases as a result of naturally or artificially induced processes occurring in “open systems”. the concept of “entropy harvesting” is inspired mainly by ideas put forward by professor guy deutscher in the book “the entropy crisis”. g. open access entropy , deutscher stated that mankind today actually faces an “entropy crisis” and not an “energy crisis” as it is commonly supposed [ ]. it takes humanity more and more energy in order to sustain an increasingly ordered environment produced by people. i quote: “what is called an energy crisis is actually an entropy crisis. it has two aspects that cannot be dissociated. the first is that the amount of energy needed to keep the entropy decrease in check may surpass the energy actually available. the second is the increasing pollution of the environment at the level of biosphere. it is precisely because we are dealing with an entropy crisis that these aspects are so intimately connected” [ ]. . entropic forces and physical systems suitable for entropy harvesting let us start from the well-known example of an entropic harvester depicted in figure a, namely a deformed polymer (rubber) band ( f  is the force applied to a polymer strip, dx is the displacement). when we stretch the rubber-band it looks from the first glance that we harvest energy (when the stretched band is released the mechanical work is done). but actually a stretched rubber-band represents an entropy harvester, exploiting so-called “entropic force”. figure . (a) the deformed with force f  polymer strip—the simplest example of the “entropy harvester”. if a polymer molecule in the strip is pulled into an extended configuration, it decreases its entropy (the stretched molecule is more ordered). randomly coiled configurations are overwhelmingly more entropy , probable; i.e. they have greater entropy [ ]. the molecule tends to increase its entropy; this gives rise to the entropy-inspired elastic force f  , given by: r nl tk f b   ( ) where bk is the boltzmann constant, t is the temperature, n is the number of monomers, l is the length of the monomer unit, the    n i irr  is the end-to-end vector (see figure ). the coefficient of proportionality nl tk b is called the entropic spring constant [ ]. notice that the entropic elastic force given by equation ( ) is proportional to temperature; this kind of temperature dependence is typical for the other kinds of entropic forces. it has been established experimentally that when a rubber-band is stretched, the elastic force is proportional to temperature: f  ~ t. figure . the model of a polymer chain.    n i irr  is the end-to-end vector. the next example of an entropic harvester is the osmotic membrane-based device, depicted in figure . consider a solution that is separated from a pure solvent by an osmotic membrane that allows only solvent molecules, not solute (depicted with triangles in figure ) to pass through. particles of solute tend to flow from the pure solvent into the solution, in order to decrease the entropy of the system [ ]. to prevent the flow, a pressure drop should be created, as depicted in figure ( ) pp  . when a pressure drop sufficient for preventing flow is applied to an osmotic system, it works as an entropy harvester. the pressure drop is given by the van’t hoff formula: v trn pp s ˆ  ( ) where v ns is the number of moles of solute per unit volume, and r̂ is the gas constant [ ]. as is typical for the entropic-driven effect, the osmotic pressure drop depends linearly on the temperature (compare with equation ( )). if we remove the pressure drop, the flow will start and the osmotic entropic harvester, shown in figure , will perform the mechanical work.     entropy , figure . to prevent osmotic flow, p must exceed p . the system represents an example of an “entropy harvester”. the so-called “hydrophobic effect” represents additional exemplification of the entropy-driven phenomena. the hydrophobic interaction originates from the disruption of hydrogen bonds between molecules of liquid water by the nonpolar solute [ ]. by aggregating together, nonpolar molecules reduce the surface area exposed to water and minimize this disruptive effect. this reducing of the surface is entropically favorable [ ]. this entropic effect leads also to the clustering of small hydrophobic particles, shown in figure . if we mix the suspension and increase the average distance between hydrophobic particles, the suspension will harvest entropy. hydrophobic interactions, like other entropic effects, increase in strength with increasing temperature [ ]. figure . clustering of hydrophobic particles dispersed in water, due to the hydrophobic effect. we supplied a number of examples representing “entropy harvesters”, however the simplest possible entropy harvester is a box containing gas, depicted in figure b. if the gas in the container expands isothermally, the force driving the piston is given by [ ]: t dx ds f   ( ) hydrophobic particles entropy , this is the entropic force which is very similar to the force and pressure supplied by equations ( ) and ( ). indeed, the internal energy of a fixed quantity of an ideal gas depends only on its temperature, and not on the volume of its container, so it is not an energy effect that tends to increase the volume of the box like gas pressure does. this implies that the pressure of an ideal gas has a purely entropic origin. . natural entropy harvesters entropy harvesting is ubiquitous in nature. entropy harvesting occurs under photosynthesis, when six molecules of water (h o) and six molecules of carbon dioxide (co ) combine to form one molecule of glucose c h o and six molecules of o . since six molecules of carbon dioxide have been replaced by six molecules of oxygen, the number of molecules in the atmosphere is not modified [ ]. hence, entropy in atmosphere is not directly affected by photosynthesis. overall entropy is nevertheless reduced because in the liquid phase six molecules of h o disappeared and only one molecule of glucose has been formed. the stored entropy could be released to provide heat at high temperature or to provide food to other organisms [ , ]. our muscles are also natural entropy harvesters. as it has been shown recently, elasticity in the giant muscle protein titin arises from entropy in a way very similar to the entropy-driven elasticity of polymer chains, described roughly by equation ( ) [ ]. . the efficiency of entropy harvesting consider one of the simplest possible entropy harvesters, i.e. a box containing gas (depicted in figure b). when we cool the container isothermally, its energy decreases, and tdsdq  obviously takes place, where dq is the amount of heat taken from the system. the last expression could be re-written as: tdq ds  ( ) dq ds in equation ( ) may be interpreted as the efficiency of energy harvesting (the harvested entropy per unit of withdrawn heat). it is seen that the efficiency of energy harvesting increases when the temperature is decreased. we can also re-write equation ( ) as: t f dx ds   ( ) it is reasonable to interpret dx ds as the efficiency of entropy harvesting related to the unit displacement of the piston. thus, we recognize that when constf   , the efficiency of energy harvesting increases with the temperature decreases. entropy , . gravity and entropy harvesting this example looks speculative compared to previous ones. verlinde in his recent paper treated gravity as an entropic force caused by changes in the information identified with material bodies [ ]. the positions and movements of particles in physics are related to space. according to verlinde, “space is therefore literally a storage space for information associated with matter” [ ]. he assumed that this information is stored in discrete bits on the holographic screens [ ]. within this approach, space is emergent and the holographic screen separates the emerged part of space, containing bodies, and stores data that describe the part of space that has not yet emerged [ – ]. consider a holographic screen, and a particle of mass m that approaches from the side at which space-time already emerged, as described in figure . at this side the physics is described in macroscopic variables, such as positions of particles; on the other side it is still formulated in terms of microscopic degrees of freedom [ ]. according to the holographic principle, the information associated with the particle with the mass of m can be mapped onto the screen that separates the two regions. eventually the particle merges with these microscopic degrees of freedom, but beforehand it changes the amount of information associated with it. the change of entropy associated with the information drop on the boundary equals [ ]: x mc ks b    ( ) this information drop gives rise to the entropic force (a is the acceleration): ma x s tf     ( ) comparing equations ( ) and ( ) yields for the temperature: ck a t b   ( ) figure . a particle with mass m approaches the holographic screen. the screen bounds the emerged part of space which contains the particle, and stores data that describe the part of space that has not yet emerged. m Δx Δs t entropy , expression ( ) supplying the temperature t coincides precisely with the so-called unruh temperature, registered by an observer in an accelerated frame moving with acceleration a [ ]. verlinde proposed to treat expression ( ) as the temperature required to cause acceleration a, and not as the temperature caused by an acceleration. in order to explain the origin of the force given by equations ( ) and ( ), verlinde likens the holographic screen to the osmotic membrane carrying temperature t, discussed in section [ ]. if gravitational force has an entropic origin, the displacement of physical bodies may be used for effective entropy harvesting, followed by the release of mechanical work. . conclusions mankind produces an increasingly ordered environment, possessing decreased entropy. sustaining this low-entropy environment requires more and more energy. this is the so-called “energy crisis”, which is actually an “entropic crisis”. however, the decreased entropy could be harvested by special devices, such as stretched polymers, human muscles and osmotic membranes. the harvested entropy may be released as mechanical work. such devices are called in this paper “entropy harvesters”, in contrast to widespread energy harvesters capturing the ambient energy and converting it into usable electrical energy. thus, an alternative approach to “energy harvesting” is proposed. “entropy harvesters” exploit the entropic force increasing with temperature. the efficiency of entropy harvesting increases when the temperature is decreased. the possibility that the gravity is the “entropic force”, opening the opportunity to harvest gravity-driven entropy decrease, is discussed. acknowledgements the author is indebted to mrs. ye bormashenko for her inestimable help in preparing this manuscript. conflict of interest the authors declare no conflict of interest. references . priya, s.; inman, d.j. energy harvesting technologies; springer: heidelberg/berlin, germany, . . beeby, s.p. tudor, m.j. white, n.m. energy harvesting vibration sources for microsystems applications, meas. sci. technol. , , r –r . . anton, s.r.; sodano, h.a. a review of power harvesting using piezoelectric materials. smart mater. struct. , , r –r . . stephen, n.g. on 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photosynthesis; john wiley & sons: new york, ny, usa, . . tskhovrebova, l.; trinick, j.; sleep, j.a.; simmons, r.m. elasticity and unfolding of single molecules of the giant muscle protein titin. nature , , – . . verlinde, e. on the origin of gravity and the laws of newton. j. high. energy phys. , , – . . bousso, r. the holographic principle. rev. modern phys. , , – . . bekenstein, j.d. universal upper bound on the entropy-to-energy ratio for bounded systems. phys. rev. d , , – . . unruh, w.g. notes on black hole evaporation. phys. rev. d , , – . © by the authors; licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution license (http://creativecommons.org/licenses/by/ . /). building energy: a review on consumptions, policies, rating schemes and standards sciencedirect available online at www.sciencedirect.comavailable online at www.sciencedirect.com sciencedirect energy procedia ( ) – www.elsevier.com/locate/procedia - © the authors. published by elsevier ltd. peer-review under responsibility of the scientific committee of the th international symposium on district heating and cooling. the th international symposium on district heating and cooling assessing the feasibility of using the heat demand-outdoor temperature function for a long-term district heat demand forecast i. andrića,b,c*, a. pinaa, p. ferrãoa, j. fournierb., b. lacarrièrec, o. le correc ain+ center for innovation, technology and policy research - instituto superior técnico, av. rovisco pais , - lisbon, portugal bveolia recherche & innovation, avenue dreyfous daniel, limay, france cdépartement systèmes Énergétiques et environnement - imt atlantique, rue alfred kastler, nantes, france abstract district heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. these systems require high investments which are returned through the heat sales. due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. the main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand forecast. the district of alvalade, located in lisbon (portugal), was used as a case study. the district is consisted of buildings that vary in both construction period and typology. three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). to estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. the results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than % for all weather scenarios considered). however, after introducing renovation scenarios, the error value increased up to . % (depending on the weather and renovation scenarios combination considered). the value of slope coefficient increased on average within the range of . % up to % per decade, that corresponds to the decrease in the number of heating hours of - h during the heating season (depending on the combination of weather and renovation scenarios considered). on the other hand, function intercept increased for . - . % per decade (depending on the coupled scenarios). the values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. © the authors. published by elsevier ltd. peer-review under responsibility of the scientific committee of the th international symposium on district heating and cooling. keywords: heat demand; forecast; climate change energy procedia ( ) – - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /) peer-review under responsibility of the scientific committee of icae – the th international conference on applied energy. . /j.egypro. . . . /j.egypro. . . © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /) peer-review under responsibility of the scientific committee of icae – the th international conference on applied energy. - available online at www.sciencedirect.com sciencedirect energy procedia ( ) – www.elsevier.com/locate/procedia - copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the th international conference on applied energy (icae ). th international conference on applied energy (icae ), - august , hong kong, china building energy: a review on consumptions, policies, rating schemes and standards mengxue lu, joseph h.k. lai* department of building service engineering, the hong kong polytechnic university, hong hong, china abstract the building and construction sectors account for more than one third of the global energy consumption. in order to understand the status quo of building energy around the world, a study, as reported here, reviewed the energy consumptions of the major countries/places, their energy policies and rating schemes and standards applicable to building energy use. the review shows that countries with abundant energy resources tend to consume more energy per person than those with less energy resources. some developing countries have green building rating schemes in place, but many others have not adopted any building energy standard. for those countries who have the standards in place, they may find it difficult to implement the standards in reality. in addition, some new building energy standards have been released lately; studies that make reference to such standards are yet to be seen. research in future should investigate how the building energy standards could be effectively adopted to reduce building energy use. copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the th international conference on applied energy (icae ). keywords: building; energy; policy; rating scheme; standard . introduction the rapid growth of the global energy consumption has caused not only the potential energy crisis but also severe environmental problems such as global warming and air pollution, which endanger people’s health and properties. therefore, intergovernmental organizations and governments around the world have put in place policies to * corresponding author. tel.: ( ) - ; fax: ( ) - . e-mail address: bejlai@polyu.edu.hk available online at www.sciencedirect.com sciencedirect energy procedia ( ) – www.elsevier.com/locate/procedia - copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the th international conference on applied energy (icae ). th international conference on applied energy (icae ), - august , hong kong, china building energy: a review on consumptions, policies, rating schemes and standards mengxue lu, joseph h.k. lai* department of building service engineering, the hong kong polytechnic university, hong hong, china abstract the building and construction sectors account for more than one third of the global energy consumption. in order to understand the status quo of building energy around the world, a study, as reported here, reviewed the energy consumptions of the major countries/places, their energy policies and rating schemes and standards applicable to building energy use. the review shows that countries with abundant energy resources tend to consume more energy per person than those with less energy resources. some developing countries have green building rating schemes in place, but many others have not adopted any building energy standard. for those countries who have the standards in place, they may find it difficult to implement the standards in reality. in addition, some new building energy standards have been released lately; studies that make reference to such standards are yet to be seen. research in future should investigate how the building energy standards could be effectively adopted to reduce building energy use. copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the th international conference on applied energy (icae ). keywords: building; energy; policy; rating scheme; standard . introduction the rapid growth of the global energy consumption has caused not only the potential energy crisis but also severe environmental problems such as global warming and air pollution, which endanger people’s health and properties. therefore, intergovernmental organizations and governments around the world have put in place policies to * corresponding author. tel.: ( ) - ; fax: ( ) - . e-mail address: bejlai@polyu.edu.hk http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf mengxue lu et al. / energy procedia ( ) – author name / energy procedia ( ) – encourage energy reduction and carbon mitigation. according to the united nations environment programme (unep), the construction and building sectors account for over one-third of the global final energy use, and billion square meters of floor areas are expected to be newly constructed in the world in the next years [ ]. for example, the residential and commercial sectors respectively account for % and % of the total energy use in the u.s. in [ ]. space heating consumes most of the energy consumption in u.s. homes ( % of total) whereas in commercial buildings, space heating consumes % of the total energy in [ , ]. as far as the commercial sector is concerned, china as a developing country does not consume as much energy as the developed countries, but shares % of the total energy use in the global residential sector [ ]. intended to understand the status quo of building energy around the world, this paper provides a review on the energy consumptions and policies of the major countries/places and the rating schemes and standards for assessing building energy use. . methodology the research method of this study consists of record data analysis and literature review. energy consumption data of main countries and places (e.g. u.s., hong kong) from to were collected from the world bank [ ]. detailed energy consumption data of the building sector were gathered from governments’ statistics reports. since the energy units used by individual countries are not identical, the conversion factors published by the international energy agency (iea) [ ] were applied to standardize all such energy units to kilo tons of oil equivalent (ktoe). building energy consumption data of the u.s., collected from the monthly energy review of energy information administration (eia), were in trillion btu [ ], where trillion (short scale) = tera (t); tbtu = . ktoe [ ]. the data of the u.k. refer to those in the energy consumption in the u.k. (ecuk) report released by the department for business, energy and industrial strategy [ ]. the energy unit adopted by the u.k. is ktoe. china’s building energy consumption data were downloaded from the official website of the national bureau of statistics of china [ ]. china’s energy unit is tons of standard coals equivalent (tce), and ktce = . ktoe. building energy data of australia were collected from the australian energy statistics; the energy unit is pj, where pj = . ktoe [ ]. building energy data of hong kong, promulgated by the electrical and mechanical services department, were in tj ( tj = . ktoe) [ ]. the literature review was proceeded by using keywords (e.g. building, energy, policy, etc.) to search publications from well-known electronic databases: science direct and springer. . energy consumptions . . main countries/places raw energy consumption data of the main countries/places were downloaded from the world bank’s website and then a series of energy consumption trends were plotted. developed countries such as the u.s. demonstrate a downward trend in energy consumption per capita whereas developing countries such as china tend to consume more energy in recent years [fig ]. as bunker fuel oil constitutes over half of singapore’s total oil demand and tankers preferred to fuel in singapore instead of the middle east before and during the iraq war, the total energy consumption of singapore peaked in [ ]. countries with abundant energy resources, such as canada and australia, tend to consume more energy per person than those with less energy resources, e.g. european union. these observations correspond with the analyzed findings on energy use per capita by country’s income level [fig ]. high-income countries consume toe per person, which is about times the level of the middle-income countries. for most of the countries studied, fossil fuel accounts for more than % of their total energy use [fig ]. among those countries, singapore shows the highest ratio ( %) [fig ]. as a country with no oil or natural gas production, singapore imported energy resources mainly from its neighboring countries [ ]. with the clean energy policy, singapore’s energy use mainly relies on natural gas, which is a kind of fossil fuel. this causes the extremely high fossil fuel share of singapore [fig ]. ranked just behind singapore, hong kong also has a high fossil fuel proportion – about %. the reason for this is that the hong kong government insists in free market economy, focusing mainly on public safety and environmental protection while imposing little intervention on energy mix author name / energy procedia ( ) – [ ]. probably because of the reliance on nuclear electricity, the fossil fuel consumption of japan was not high until when the fukushima nuclear leakage occurred. as a result, nuclear electricity was substituted by fossil fuel electricity and the fossil fuel’s share surged in the ensuing two years: rose from about % to % [fig ]. renewable energy used to be characterized by advanced technology and high investment. however, low-income countries has a low proportion of fossil fuel energy consumption [fig ], which implies their heavy reliance on renewable energy. conversely, the proportion of fossil fuel energy consumption of high- and middle- income countries was high, at around %. before , the high-income countries had a slightly higher proportion of fossil fuel than the middle-income countries [fig ]. fig . energy use per capita of major places fig . energy use per capita by countries’ income level fig . fossil fuel energy consumption (% of total energy consumption) of major places fig . fossil fuel energy consumption (% of total energy consumption) by countries’ income level . . building sector in the u.s., both the residential and commercial sectors consume about ktoe of energy per year [fig ]. with slight fluctuations over the years, the total energy consumption of the two sectors was close to ktoe. fig . building energy consumption in the u.s. fig . building energy consumption in china mengxue lu et al. / energy procedia ( ) – author name / energy procedia ( ) – encourage energy reduction and carbon mitigation. according to the united nations environment programme (unep), the construction and building sectors account for over one-third of the global final energy use, and billion square meters of floor areas are expected to be newly constructed in the world in the next years [ ]. for example, the residential and commercial sectors respectively account for % and % of the total energy use in the u.s. in [ ]. space heating consumes most of the energy consumption in u.s. homes ( % of total) whereas in commercial buildings, space heating consumes % of the total energy in [ , ]. as far as the commercial sector is concerned, china as a developing country does not consume as much energy as the developed countries, but shares % of the total energy use in the global residential sector [ ]. intended to understand the status quo of building energy around the world, this paper provides a review on the energy consumptions and policies of the major countries/places and the rating schemes and standards for assessing building energy use. . methodology the research method of this study consists of record data analysis and literature review. energy consumption data of main countries and places (e.g. u.s., hong kong) from to were collected from the world bank [ ]. detailed energy consumption data of the building sector were gathered from governments’ statistics reports. since the energy units used by individual countries are not identical, the conversion factors published by the international energy agency (iea) [ ] were applied to standardize all such energy units to kilo tons of oil equivalent (ktoe). building energy consumption data of the u.s., collected from the monthly energy review of energy information administration (eia), were in trillion btu [ ], where trillion (short scale) = tera (t); tbtu = . ktoe [ ]. the data of the u.k. refer to those in the energy consumption in the u.k. (ecuk) report released by the department for business, energy and industrial strategy [ ]. the energy unit adopted by the u.k. is ktoe. china’s building energy consumption data were downloaded from the official website of the national bureau of statistics of china [ ]. china’s energy unit is tons of standard coals equivalent (tce), and ktce = . ktoe. building energy data of australia were collected from the australian energy statistics; the energy unit is pj, where pj = . ktoe [ ]. building energy data of hong kong, promulgated by the electrical and mechanical services department, were in tj ( tj = . ktoe) [ ]. the literature review was proceeded by using keywords (e.g. building, energy, policy, etc.) to search publications from well-known electronic databases: science direct and springer. . energy consumptions . . main countries/places raw energy consumption data of the main countries/places were downloaded from the world bank’s website and then a series of energy consumption trends were plotted. developed countries such as the u.s. demonstrate a downward trend in energy consumption per capita whereas developing countries such as china tend to consume more energy in recent years [fig ]. as bunker fuel oil constitutes over half of singapore’s total oil demand and tankers preferred to fuel in singapore instead of the middle east before and during the iraq war, the total energy consumption of singapore peaked in [ ]. countries with abundant energy resources, such as canada and australia, tend to consume more energy per person than those with less energy resources, e.g. european union. these observations correspond with the analyzed findings on energy use per capita by country’s income level [fig ]. high-income countries consume toe per person, which is about times the level of the middle-income countries. for most of the countries studied, fossil fuel accounts for more than % of their total energy use [fig ]. among those countries, singapore shows the highest ratio ( %) [fig ]. as a country with no oil or natural gas production, singapore imported energy resources mainly from its neighboring countries [ ]. with the clean energy policy, singapore’s energy use mainly relies on natural gas, which is a kind of fossil fuel. this causes the extremely high fossil fuel share of singapore [fig ]. ranked just behind singapore, hong kong also has a high fossil fuel proportion – about %. the reason for this is that the hong kong government insists in free market economy, focusing mainly on public safety and environmental protection while imposing little intervention on energy mix author name / energy procedia ( ) – [ ]. probably because of the reliance on nuclear electricity, the fossil fuel consumption of japan was not high until when the fukushima nuclear leakage occurred. as a result, nuclear electricity was substituted by fossil fuel electricity and the fossil fuel’s share surged in the ensuing two years: rose from about % to % [fig ]. renewable energy used to be characterized by advanced technology and high investment. however, low-income countries has a low proportion of fossil fuel energy consumption [fig ], which implies their heavy reliance on renewable energy. conversely, the proportion of fossil fuel energy consumption of high- and middle- income countries was high, at around %. before , the high-income countries had a slightly higher proportion of fossil fuel than the middle-income countries [fig ]. fig . energy use per capita of major places fig . energy use per capita by countries’ income level fig . fossil fuel energy consumption (% of total energy consumption) of major places fig . fossil fuel energy consumption (% of total energy consumption) by countries’ income level . . building sector in the u.s., both the residential and commercial sectors consume about ktoe of energy per year [fig ]. with slight fluctuations over the years, the total energy consumption of the two sectors was close to ktoe. fig . building energy consumption in the u.s. fig . building energy consumption in china mengxue lu et al. / energy procedia ( ) – author name / energy procedia ( ) – on the other side, the household sector, construction sector, and the retail, hotel, and restaurant sectors in china, for example in , collectively consume about half of the energy used by the commercial and residential sectors in the u.s. [fig ]. in the u.k., the domestic sector consumes about times the energy used by the commercial sector. with mild dips in some years, the annual total energy uses of the two sectors stood at around ktoe [fig ]. in australia, the energy consumptions of the residential and commercial sectors have gradually increased since , with their total amount approaching ktoe in [fig ]. fig . building energy consumption in the u.k. fig . building energy consumption in australia . energy policies building energy policy is a critical factor affecting the achievement of building energy efficiency [ ]. countries with limited natural resources tend to be more active in promoting green buildings or zero-carbon buildings. for instance, in japan, the act on the rational use of energy was launched in and revised several times later on until [ ]. besides mandatory regulations, economic incentive measures are also adopted by the japanese government in promoting green buildings and energy-efficient residential buildings [ ]. in singapore, the green building masterplan, which is also known as the green mark incentive scheme for new buildings, was first released by building and construction authority (bca) in and the latest release was in [ ]. each time, the incentive scheme allocates millions of dollars to encourage building owners to make their new buildings achieve at least the green mark gold rating [ ]. in , the hk campaign was promulgated by the hong kong green building council with the aim of cutting % of the electricity consumption by (referencing the baseline) [ ]. referring to the four categories of building energy policy instruments defined by the unep [ ], most building energy policies launched in china can be classified as control and regulatory policy instruments (e.g. management rules on residential building energy efficiency), and the other policy instruments include tax, energy label and carbon trading [ ]. in india, the energy conservation building code (ecbc) was issued in as its first building energy code [ ]. newly revised in , the ecbc focuses on large commercial buildings and specifies minimum requirements for energy performance on mechanical and hvac systems, renewable energy, etc. [ ]. . rating schemes according to the world green building council, there are more than green building rating tools applied worldwide, including breeam, leed, beam plus, etc. [ ]. developed in by the u.k. building research establishment ltd., breeam is believed to be the first building environmental performance rating system in the world and it is now employed by countries covering all building, infrastructure and master-planning projects [ ]. released by the u.s. green building council in , leed devoted to promote energy-efficient, cost- effective building designs that are healthy for occupants [ ]. in hong kong, the commonly used green building assessment tool is beam plus, which was upgraded from beam – the previous version issued by the hong kong green building council in . beam plus is tailored for the hong kong’s high-rise, high-density built environment [ ]. the india green building council also provides specific rating systems for different types of buildings [ ]. other eminent building rating schemes include green star of australia, bca green mark scheme of singapore, asgb of china, and casbee of japan [ ]. residential sector commercial sector (ktoe) author name / energy procedia ( ) – recently, a study compared the evaluation criteria of renowned green building rating systems and the results demonstrate that water and material aspects are evaluated by all the schemes, whereas energy, indoor environment, site, land and outdoor environment, innovation, waste, construction project management are key criteria evaluated by most of the rating systems [ ]. . standards building energy codes and standards, by setting up minimum requirements for energy-efficient building design, construction, operation and management, play an important role in achieving building energy efficiency. however, a survey result of building energy regulations reveals that % of the surveyed countries, most of which being developing countries, do not have building energy standards at all [ ]. international and national organizations such as iso and ashrae have published standards on building energy efficiency and building energy audit. so far, there are over iso standards concerning energy efficiency (e.g. iso serial standards) [ ]. for instance, iso illustrates energy management system requirements for organizations to achieve energy reduction and save cost while iso introduces energy audit procedures to general organizations [ , ]. issued in , iso focuses on energy performance of buildings and specifies calculation methods for building energy assessment [ ]. previous studies on building carbon emissions (e.g. [ , ]) were commonly conducted with reference to the greenhouse gas protocol. newly published iso , focused on carbon audit for buildings [ ], has not yet attracted much attention from researchers. in contrast, iso or iso has been frequently studied [ , ]. the literature search completed so far could hardly find any published studies on iso and only a few papers mentioned iso [ ]. as regards ashrae, standard . is a popular building energy standard cited by reviewed papers, especially those focused on commercial buildings and computer simulations [ ]. . conclusions in developed countries with sufficient natural resources, the consumption of fossil fuel is significantly higher than that in developing countries. in order to curb the global warming resultant from the massive use of fossil fuel, those developed countries should demonstrate more determination on energy reduction and introduce more measures to encourage the use of renewable energy. as developing countries are likely to consume more energy in parallel to the expansion of their commercial sector, the policy-makers of such countries should formulate measures for minimizing the energy consumptions of commercial buildings. some developing countries have green building rating schemes in place, but a wider adoption of such schemes necessitates more promotion to, and acceptance by, the industries, building owners and end-users. many developing countries have not adopted any building energy standard and those who have the standards in place may find it difficult to implement the standards in reality. moreover, even newly published papers on building energy do not refer to the newest building energy standards. research in future should investigate how the building energy standards could be effectively adopted to reduce building energy use. acknowledgement this work was supported by a grant from the research grants council of the hong kong special administrative region, china (project no. polyu / e). references [ ] global status report , unep, http://www.worldgbc.org/sites/default/files/unep% _gabc_en% % web% .pdf [accessed nd may, ] [ ] use of energy in the u.s., eia (u.s.), https://www.eia.gov/energyexplained/index.cfm?page=us_energy_use [accessed nd may, ] [ ] residential energy consumption survey, eia (u.s.), https://www.eia.gov/consumption/residential/data/ / [accessed nd may, ] [ ] energy use in commercial buildings, eia (u.s.), https://www.eia.gov/energyexplained/index.cfm?page=us_energy_commercial mengxue lu et al. / energy procedia ( ) – author name / energy procedia ( ) – on the other side, the household sector, construction sector, and the retail, hotel, and restaurant sectors in china, for example in , collectively consume about half of the energy used by the commercial and residential sectors in the u.s. [fig ]. in the u.k., the domestic sector consumes about times the energy used by the commercial sector. with mild dips in some years, the annual total energy uses of the two sectors stood at around ktoe [fig ]. in australia, the energy consumptions of the residential and commercial sectors have gradually increased since , with their total amount approaching ktoe in [fig ]. fig . building energy consumption in the u.k. fig . building energy consumption in australia . energy policies building energy policy is a critical factor affecting the achievement of building energy efficiency [ ]. countries with limited natural resources tend to be more active in promoting green buildings or zero-carbon buildings. for instance, in japan, the act on the rational use of energy was launched in and revised several times later on until [ ]. besides mandatory regulations, economic incentive measures are also adopted by the japanese government in promoting green buildings and energy-efficient residential buildings [ ]. in singapore, the green building masterplan, which is also known as the green mark incentive scheme for new buildings, was first released by building and construction authority (bca) in and the latest release was in [ ]. each time, the incentive scheme allocates millions of dollars to encourage building owners to make their new buildings achieve at least the green mark gold rating [ ]. in , the hk campaign was promulgated by the hong kong green building council with the aim of cutting % of the electricity consumption by (referencing the baseline) [ ]. referring to the four categories of building energy policy instruments defined by the unep [ ], most building energy policies launched in china can be classified as control and regulatory policy instruments (e.g. management rules on residential building energy efficiency), and the other policy instruments include tax, energy label and carbon trading [ ]. in india, the energy conservation building code (ecbc) was issued in as its first building energy code [ ]. newly revised in , the ecbc focuses on large commercial buildings and specifies minimum requirements for energy performance on mechanical and hvac systems, renewable energy, etc. [ ]. . rating schemes according to the world green building council, there are more than green building rating tools applied worldwide, including breeam, leed, beam plus, etc. [ ]. developed in by the u.k. building research establishment ltd., breeam is believed to be the first building environmental performance rating system in the world and it is now employed by countries covering all building, infrastructure and master-planning projects [ ]. released by the u.s. green building council in , leed devoted to promote energy-efficient, cost- effective building designs that are healthy for occupants [ ]. in hong kong, the commonly used green building assessment tool is beam plus, which was upgraded from beam – the previous version issued by the hong kong green building council in . beam plus is tailored for the hong kong’s high-rise, high-density built environment [ ]. the india green building council also provides specific rating systems for different types of buildings [ ]. other eminent building rating schemes include green star of australia, bca green mark scheme of singapore, asgb of china, and casbee of japan [ ]. residential sector commercial sector (ktoe) author name / energy procedia ( ) – recently, a study compared the evaluation criteria of renowned green building rating systems and the results demonstrate that water and material aspects are evaluated by all the schemes, whereas energy, indoor environment, site, land and outdoor environment, innovation, waste, construction project management are key criteria evaluated by most of the rating systems [ ]. . standards building energy codes and standards, by setting up minimum requirements for energy-efficient building design, construction, operation and management, play an important role in achieving building energy efficiency. however, a survey result of building energy regulations reveals that % of the surveyed countries, most of which being developing countries, do not have building energy standards at all [ ]. international and national organizations such as iso and ashrae have published standards on building energy efficiency and building energy audit. so far, there are over iso standards concerning energy efficiency (e.g. iso serial standards) [ ]. for instance, iso illustrates energy management system requirements for organizations to achieve energy reduction and save cost while iso introduces energy audit procedures to general organizations [ , ]. issued in , iso focuses on energy performance of buildings and specifies calculation methods for building energy assessment [ ]. previous studies on building carbon emissions (e.g. [ , ]) were commonly conducted with reference to the greenhouse gas protocol. newly published iso , focused on carbon audit for buildings [ ], has not yet attracted much attention from researchers. in contrast, iso or iso has been frequently studied [ , ]. the literature search completed so far could hardly find any published studies on iso and only a few papers mentioned iso [ ]. as regards ashrae, standard . is a popular building energy standard cited by reviewed papers, especially those focused on commercial buildings and computer simulations [ ]. . conclusions in developed countries with sufficient natural resources, the consumption of fossil fuel is significantly higher than that in developing countries. in order to curb the global warming resultant from the massive use of fossil fuel, those developed countries should demonstrate more determination on energy reduction and introduce more measures to encourage the use of renewable energy. as developing countries are likely to consume more energy in parallel to the expansion of their commercial sector, the policy-makers of such countries should formulate measures for minimizing the energy consumptions of commercial buildings. some developing countries have green building rating schemes in place, but a wider adoption of such schemes necessitates more promotion to, and acceptance by, the industries, building owners and end-users. many developing countries have not adopted any building energy standard and those who have the standards in place may find it difficult to implement the standards in reality. moreover, even newly published papers on building energy do not refer to the newest building energy standards. research in future should investigate how the building energy standards could be effectively adopted to reduce building energy use. acknowledgement this work was supported by a grant from the research grants council of the hong kong special administrative region, china (project no. polyu / e). references [ ] global status report , unep, http://www.worldgbc.org/sites/default/files/unep% _gabc_en% % web% .pdf [accessed nd may, ] [ ] use of energy in the u.s., eia (u.s.), https://www.eia.gov/energyexplained/index.cfm?page=us_energy_use [accessed nd may, ] [ ] residential energy consumption survey, eia (u.s.), https://www.eia.gov/consumption/residential/data/ / [accessed nd may, ] [ ] energy use in commercial buildings, eia (u.s.), https://www.eia.gov/energyexplained/index.cfm?page=us_energy_commercial mengxue lu et al. / energy procedia ( ) – author name / energy procedia ( ) – [ ] diana Ürge-vorsatz, energy end-use: buildings, http://www.iiasa.ac.at/web/home/research/flagship-projects/global-energy- assessment/gea_chapter _buildings_hires.pdf [accessed nd may, ] [ ] energy use, world bank, https://data.worldbank.org/indicator/eg.use.pcap.kg.oe?locations=at [accessed nd may, ] [ ] unit converter, iea, http://www.iea.org/statistics/resources/unitconverter/ [accessed nd may, ] [ ] monthly energy review, eia (u.s.), https://www.eia.gov/totalenergy/data/monthly/ [accessed nd may, ] [ ] energy consumption in the uk, department for business, energy and industrial strategy (u.k.), july , https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/ /ecuk_ .pdf [accessed nd may, ] [ ] total energy consumption by sector, national bureau of statistics (china), http://data.stats.gov.cn/english/easyquery.htm?cn=c [accessed nd may, ] [ ] australian energy statistics, department of industry, innovation and science (australia), https://www.industry.gov.au/office-of-the-chief- economist/publications/pages/australian-energy-statistics.aspx# [accessed nd may, ] [ ] hong kong energy end-use data , emsd (hong kong), https://www.emsd.gov.hk/filemanager/en/content_ /hkeeud .pdf [accessed nd may, ] [ ] international energy outlook , eia (u.s.), https://www.netl.doe.gov/energy-analyses/pubs/ _internationalenergyoutlook.pdf [accessed nd may, ] [ ] piped natural gas and liquefied natural gas, energy market authority (singapore), https://www.ema.gov.sg/piped_natural_gas_and_liquefied_natural_gas.aspx [accessed nd may, ] [ ] energy supplies, environment bureau (hk), http://www.enb.gov.hk/en/about_us/policy_responsibilities/energy.html [accessed nd may, ] [ ] jian zuo, ben read, stephen pullen, qian shi. achieving carbon neutrality in commercial building developments - perceptions of the construction industry, habitat international ( ) - [ ] act on the rational use of energy, japan, http://www.japaneselawtranslation.go.jp/law/detail_main?id= &vm= &re= [accessed nd may, ] [ ] xiaosen huo, ann t.w. yu, comparison of green building policies in asian countries or regions, proceedings of the st international symposium on advancement of construction management and real estate, , singapore; springer, , pp - [ ] green building masterplan, building and construction authority (singapore), https://www.bca.gov.sg/greenmark/others/ rd_green_building_masterplan.pdf [accessed nd may, ] [ ] hk campaign, hong kong green building council, https://www.hkgbc.org.hk/hk /eng/ [accessed nd may, ] [ ] beijia huang, volker mauerhofer, yong geng. analysis of existing building energy saving policies in japan and china, journal of cleaner production ( ) - [ ] ecbc , bureau of energy efficiency (india), https://beeindia.gov.in/content/buildings [accessed nd may, ] [ ] world green building council, http://www.worldgbc.org/rating-tools [accessed nd may, ] [ ] breem, https://www.breeam.com [accessed nd may, ] [ ] leed, https://new.usgbc.org/leed [accessed nd may, ] [ ] beam, https://www.beamsociety.org.hk/en_index.php [accessed nd may, ] [ ] igbc, https://igbc.in/igbc/redirecthtml.htm?redval=showratingsysnosign [accessed nd may, ] [ ] ming shan, bon-gang hwang, green building rating systems, global reviews of practices and research efforts, sustainable cities and society ( ) – [ ] joseph iwaro, abraham mwasha, a review of building energy regulation and policy for energy conservation in developing countries, energy policy ( ) – [ ] iso, https://www.iso.org/news/ / /ref .html [accessed nd may, ] [ ] iso : , energy management systems -- requirements with guidance for use [ ] iso : , energy audits -- requirements with guidance for use [ ] iso : , energy performance of buildings -- energy needs for heating and cooling, internal temperatures and sensible and latent heat loads [ ] joseph lai, francis yik, chun-sing man, carbon audit: a literature review and an empirical study on a hotel, facilities ( ) - [ ] joseph lai, carbon footprints of hotels: analysis of three archetypes in hong kong, sustainable cities and society ( ) - [ ] iso : , energy savings -- sustainability in buildings and civil engineering works [ ] harish kanneganti, bhaskaran gopalakrishnan, ed crowe, omar al-shebeeb, tarun yelamanchi, ashish nimbarte, et el. specification of energy assessment methodologies to satisfy iso energy management standard, sustainable energy technologies and assessments ( ) – [ ] bojana jovanović, jovan filipović, iso standard-based energy management maturity model – proposal and validation in industry, journal of cleaner production ( ) e [ ] jacopo vivian, angelo zarrella, giuseppe emmi, michele de carli. an evaluation of the suitability of lumped-capacitance models in calculating energy needs and thermal behavior of buildings, energy and buildings ( ) – [ ] a.p.melo, m.j.sorgato, r.lamberts, building energy performance assessment: comparison between ashrae standard . and brazilian regulation, energy and buildings ( ) – london, saturday october medical journal tomorrow's contraceptives-yesterday's problem? in research into contraception seemed full of promise. new areas were being explored, and with the perils of over- population becoming widely recognised funds for this research were readily available. at the end of the decade the picture has changed. in many developed countries population growth has slowed. in the developing world, though there has been some decline in fertility, the main problem with population control is now seen to be making the contraceptives we have both available and culturally accept'able-not developing new methods. furthermore, in most industrialised nations the amount of government spending on contraceptive research has levelled out or declined since , and of today's budget the proportion contributed by institutions and pharmaceutical companies is about half of what it was years ago. finally, worthwhile results from this research have proved elusive: for example, the development of a vaccine against pregnancy has run into many problems, and the "male pill" seems as far away as ever. referring to some of these difficulties in his introduction to the british medical bulletin's issue on reproduction, professor r v short reminds us that our current preoccupation with recession and the energy crisis should not obscure the pressing problem of world overpopulation. the decline in the british birth rate now seems to have halted, and women are becoming disenchanted with the limitations of oral contraceptives and intrauterine devices. as more side effects are discovered public confidence in existing methods of contraception will be eroded further. a world health organisation research programme, applying existing knowledge, has failed to produce new contraceptives of widespread applicability. we need more basic research, and the british medical bulletin's wide-ranging series of reviews suggests several approaches. immunology provides promising possibilities: vaccination against pregnancy can be carried out by immunising women against pregnancy-specific proteins. primates and indeed human beings have been immunised against the s-subunit of chorionic gonadotrophin with the aim of making pregnancy fail as soon as the gonadotrophin is produced. unfortunately a form of tolerance develops, so that miscarriages occur later and later in pregnancy. perhaps this problem could be avoided by immunisation against spermatozoa, or against the complex proteins of the zona pellucida of the ovum-or by immunological attack against other transmitters which the conceptus produces before implantation to signal its existence british medical journal . all reproduction rights reserved. to the mother. implantation is made possible by the persistence of the corpus luteum, which is itself vulnerable to luteolytic agents (such as prostaglandins or diethylstilboestrol): luteolysis could also be achieved by inhibition of luteotrophic hormones, using analogues of chorionic gonadotrophin or agents which interfere with binding at luteinising-hormone receptors. developing a male pill requires suppression of spermato- genesis without loss of libido. this can be produced by gestogens in combination with testosterone implants, or by cyproterone acetate-which, although it causes oligospermia and decreased sperm motility, seems a poor contraceptive. oligospermia might be achieved with normal plasma testo- sterone concentrations by developing a synthetic analogue of "inhibin," a testicular hormone which acts on the pituitary (independently of testosterone) to decrease the production of follicle-stimulating hormone. nevertheless, inhibin has proved extremely difficult to isolate and would probably be equally difficult to synthesise and administer. other possibilities include antiprogestins to prevent the action of progesterone on the endometrium, or analogues of gonadotrophin-releasing hormone to exhaust the pituitary supply of gonadotrophins. but perhaps the most attractive idea is the mimicking of "nature's contraceptive"-the infertility associated with lactation. anovulation during lactation appears to be caused by high concentrations of prolactin acting on the hypothalamus to inhibit the production of gonadotrophin-releasing hormone. clarification of this mechanism might lead to a more physiological method of contraception. in all these possibilities the gap between theory and application is still wide, and inevitably some possibilities will be ruled out by unwanted side effects. even so, as professor short points out, not all side effects are unwanted, and our goal should be "healthy infertility"-contraception which promotes good health rather than compromising it. short, r v, british medical bulletin, , , . obtainable from the british council, davies street, london wiy aa, price £ . nuttall, i d, et al, british medical journal, , , . aitken, r j, british medical bulletin, , , . hearn, j p, in maternal recognition of pregnancy: ciba foundation symposium no . amsterdam, excerpta medica, . talwar, g p, et al, proceedings of the national academy of sciences, , , . heap, r b, flint, a p, and gadsby, j e, british medical bulletin, , , . mcneilly, a s, british medical bulletin, , , . no page o n a p ril b y g u e st. p ro te cte d b y co p yrig h t. h ttp ://w w w .b m j.co m / b r m e d j: first p u b lish e d a s . /b m j. . . o n o cto b e r . d o w n lo a d e d fro m http://www.bmj.com/ articles dry needling certification / the journal of manual & manipulative therapy, the journal of manual & manipulative therapy vol. no. ( ), - myofascial trigger points: translating molecular theory into manual therapy address all correspondence and request for reprints to: john m. mcpartland washington street ext middlebury, vt usa mcpruitt@verizon.net abstract: theories regarding the molecular pathophysiology of myofascial trigger points (mftrps) have undergone fundamental revisions in recent years. new research suggests that mftrps are evoked by the abnormal depolarization of motor endplates. the motor endplate transduces electrical potential into muscle contraction. this review article expands the proposed etiology to include presynaptic, synaptic, and postsynaptic mechanisms, such as excessive release of acetycholine (ach), defects of acetylcholinesterase, and upregulation of nicotinic ach receptors, respectively. dysfunctional motor endplates and sustained muscular contraction give rise to a localized “atp energy crisis” associated with sensory and autonomic reflex arcs that is sustained by central sensitization. this working hypothesis has given rise to several new approaches in the treatment of mftrps. k e y wo rd s : m y o f a s c i a l tr i g g e r p o i n t s , m o t o r e n d p l a t e , a c e t y c h o l i n e r e c e p t o r, acetylcholinesterase john m. mcpartland, do, ms david g. simons, md simons, travell, and simons defined the myofascial trigger point (mftrp) as “…a hyperirritable spot in skeletal muscle that is associated with a hypersensitive palpable nodule in a taut band. the spot is tender when pressed, and can give rise to characteristic referred pain, motor dysfunction, and autonomic phenomena…” thus each mftrp contains a sensory component, a motor component, and an autonomic component. these components comprise a new “integrated hypothesis” regarding the etiology of mftrps . this hypothesis involves local myofascial tissues, the central nervous system (cns), and systemic biomechanical factors. the “integrated hypothesis” has changed our approach to treating mftrps. the purpose of this paper is to review new concepts concerning mftrps and to describe our evolving approach to their treatment. motor endplate: epicenter of the myofascial trigger point simons implicated the motor endplate as the central etiology of mftrps. the motor endplate is synonymous with the neuromuscular junction (the first term de- scribes structure, the latter term describes function); it is the site where an -motor neuron synapses with its target muscle fibers. the -motor neuron terminates in multiple swellings termed presynaptic boutons. each bouton contains many acetylcholine (ach) vesicles, clustered around structures called dense bars (figure ). voltage-sensitive calcium channels (vsccs, specifi- cally p/q-type vsccs) also cluster near dense bars. when voltage running down an -motor neuron reaches vsccs in the bouton, the vscc channels open, leading to an influx of calcium ions (ca +) into the bouton from the extracellular space. the influx of ca + causes the ach vesicles to release their transmitter into the synaptic cleft (figure ). across the synaptic cleft, the postsynaptic muscle cell membrane forms junctional folds that are lined with nicotinic ach receptors (nachs). the nach is a ligand- gated cation channel, and ach is its ligand. binding of myofascial trigger points: translating molecular theory into manual therapy / ach to nach opens its channel, allowing sodium ions (na+) and potassium ions (k+) to move in and out of the muscle cell membrane. movement of na+ and k+ depolar- izes the postsynaptic cell, forming a miniature endplate potential (mepp). a sufficient number of mepps activate vsccs (specifically l-type vsccs), which subsequently trigger another ca + channel, the ryanodine receptor. the ryanodine receptor is imbedded in the membrane of an intracellular structure called the sarcoplasmic reticulum, which houses intracellular stores of ca +. activation of the ryanodine receptor releases ca + from the sarcoplasmic reticulum into the cytoplasm of the muscle cell. this triggers the interaction between actin and myosin, and the sarcomere contracts. electromyography (emg) studies of mftrps have reported spontaneous electrical activity (sea) in mftrps, while adjacent muscle tissues are electrically silent . hubbard and berkoff originally attributed the source of sea action potentials to sympathetically activated intrafusal muscle spindles. these researchers were unaware of previous work by liley of new zealand, who had demonstrated that sea was a consequence of ach release at motor endplates . simons “connected the dots” by correlating sea with “endplate noise” that had been described by electromyographers, and he linked sea to excessive ach release, which he proposed as the primary cause of mftrp development. this “motor endplate” hypothesis was tested in hong’s laboratory , where mftrps were injected with botulinum toxin type a, which blocks ach release at the motor endplate. this treatment significantly decreased sea activity. mense et al confirmed the hypothesis using a rat mftrp model. they injected diisopropylfluorophosphate (dfp), a drug that increases synaptic ach, into the proximal half of the gastrocnemius muscle, and the motor nerve was electrically stimulated for - min to induce muscle contractions. the distal half of the muscle, which performed the same contractions, served as a control. proximal and distal sections of the muscle were then examined for morphological changes. the dfp-injected proximal half exhibited significantly more contracted and torn muscle fibers compared to the distal half of the muscle. myofascial tension may play a role in excess ach release. chen and grinnell showed that a % increase in muscle stretch at the motor endplate evoked a % increase in ach release. these researchers postulated that tension upon integrins (cell-surface proteins that bind connective tissues) in the presynaptic membrane was transduced mechanically into ach vesicle release. expanding the endplate hypothesis simons’ description of a presynaptic dysfunction (excessive ach release), however, is only one way to interpret the “endplate hypothesis.” we can expand the hypothesis to include presynaptic, intrasynaptic, and postsynaptic dysfunctions . intrasynaptic ach must be deactivated; otherwise, it will continue to activate nachrs in the muscle cell membrane. ach is normally deactivated by the enzyme acetylcholinesterase (ache), which is held in the synaptic cleft by a structural protein (collagen q, colq) that anchors it to the plasma mem- brane (figure ). ache deficiency permits excess ach fig. : the motor endplate – proposed site of trigger point dysfunction. top illustration: the junction between the -motor neuron and the muscle fiber. bottom il- lustration: presynaptic boutons are separated from the postsynaptic muscle cell by the synaptic cleft. within each bouton are many vesicles containing ach, clus- tered around dense bars (db). also clustered around the db are calcium channels. the db is the site of ach release into the synaptic cleft. across the synaptic cleft from the db, the postsynaptic muscle cell membrane forms junctional folds that are lined with nicotinic ach receptors (nach). ach released into the synaptic cleft activates nach receptors, then is inactivated by the acetylcholinesterase enzyme (ache). illustration courtesy of mcpartland. / the journal of manual & manipulative therapy, to accumulate in the synaptic cleft, tonically activating nachrs. several genetic mutations cause ache defi- ciency, including mutations in colq. the gene for ache expresses several splice variants , which are alternative ways in which a gene’s protein-coding sections (exons) are joined together to create a messenger rna molecule and its translated protein. ache splice variants are less effective at deactivating ach, and the expression of these splice variants can be induced by psychological and physi- cal stress . drugs and other chemicals may cause ache deficiency. dfp, the drug used in the aforementioned experiment by mense et al , is an ache antagonist. organophosphate pesticides are ache antagonists, and poisoning by these pesticides causes changes in motor endplates and mftrp-like pathology - . muscle damage caused by ache antagonists has been reduced by pre- treatment with postsynaptic l-type vscc blockers such as quinidine and diltiazem . postsynaptically, a “gain-of-function” defect of the nachr may confer muscle hyperexcitability, a hallmark of mftrps. gain of function refers to an increased response by the nachr, via several possible mechanisms: nachr overexpression, constitutively-active nachrs , nachrs that gain responsiveness to choline (an ordinary serum metabolite) , or nachrs whose channels remain open longer than normal . the nachr is an assembly of five subunits; at least genes encode these subunits, so that the nachr is particularly susceptible to mutational defects. motor endplate nachrs express a unique subunit assembly, whereas nachrs in the central nervous system and in autonomic nerves express a different subunit configuration . the relative consequences of presynaptic, synaptic, and postsynaptic dysfunctions are under debate. wang et al used a variety of pharmacological tools to con- clude that presynaptic mechanisms modulate the motor endplate rather than synaptic (ache) or postsynaptic (nachr density) mechanisms. conversely, nakanishi et al determined that postsynaptic manipulation (using alpha-bungarotoxin, an nachr antagonist) modulated motor endplates to a greater degree than presynaptic manipulation (using botulinum toxin, an inhibitor of ach release). motor component mftrps have a motor component, whereas tender points found in patients with fibromyalgia do not. mftrps have been biopsied and found to contain “…contraction knots…” described as “…large, rounded, darkly staining muscle fibers and a statistically significant increase in the average diameter of muscle fibers…” . thus the structure of contraction knots differed from that of normal muscle fibers. functionally, excessive motor activity initiates several perverse mechanisms that cause mftrps to persist. muscle contraction compresses local sensory nerves, which reduces the axoplasmic transport of molecules that normally inhibit ach release , . muscle contraction also compresses local blood vessels, reducing the local supply of oxygen. reduced oxygen, combined with the metabolic demands generated by contracted muscles, results in a rapid depletion of local adenosine triphosphate (atp). the resultant “atp energy crisis” triggers a cascade of pre- and postsynaptic decompensations. presynaptic atp directly inhibits ach release , so depletion of atp increases ach release. postsynaptic atp powers the ca + pump that returns ca + to the sarcoplasmic reticulum. hence, loss of atp impairs the reuptake of ca +, which increases contractile activity, creating a vicious cycle . excess ca + may snowball into “ca +-induced ca + release,” where ca + induces further ca + release from intracel- lular stores via ryanodine receptors, triggering actin and myosin, leading to muscle spasm. some controversy surrounds adenosine, a breakdown product of atp. adenosine normally decreases motor endplate activity by activating presynaptic adenosine a receptors, which reduce p/q vscc currents, thus reducing ach release . however, high levels of synaptic adenosine, from excess atp breakdown (as is hypothesized to occur in the atp energy crisis model), may activate postsynap- tic adenosine a receptors, which recruit l-type vsccs currents, thus triggering muscle contraction . mftrps exert profound yet unpredictable influences upon motor function. mftrps may excite or inhibit normal motor activity in their muscle of origin or in functionally related muscles. latent mftrps can be equally influential upon motor function. motor inhibi- tion is often identified clinically as muscle weakness, but treatment often focuses on strengthening exercises that only augment abnormal muscle substitution until the inhibiting mftrps are inactivated. this inhibition can also cause poor coordination and muscle imbalances. these mftrp effects have gone largely unrecognized because of a lack of published research studies. headly has explored these effects using surface electromyography, describing inhibition of the trapezius by mftrps in the same muscle , inhibition of anterior deltoid by mftrps in the infraspinatus , inhibition of gluteal muscles by mftrps in the quadratus lumborum , and excitation (referred spasm) of the paraspinals by mftrps in the tensor fascia lata , . sensory component mftrps are painful. pain begins in peripheral tissues as nociception, transmitted by a and c-fiber afferent sensory neurons (nociceptors). mechanical pressure, thermal stimuli, and many chemicals activate nocicep- tors; potassium ions, protons, and free o radicals are by-products of muscle metabolism and the hypothesized “atp energy crisis.” histamine is released from mast cells that migrate into injured tissues. serotonin is released from platelets after they are exposed to platelet activat- myofascial trigger points: translating molecular theory into manual therapy / ing factor (released from the mast cells). bradykinin is cleaved from serum proteins. all of these chemical “activators” bind to receptors in the nociceptor and initi- ate an action potential. “sensitizers” are also released from damaged tissue; examples include prostaglandins, leukotrienes, and substance p. sensitizers decrease the activation threshold of a neuron, so that the nociceptor fires with less activation. this leads to peripheral sen- sitization and hyperalgesia. sensitizing substances may also generate a focal demyelination of sensory nerves. demyelination creates abnormal impulse-generating sites (aigs), capable of generating ectopic nociceptive impulses . shah et al used a microdialysis needle to sample tissue fluids from the upper trapezius muscle in nine subjects; elevated concentrations of protons, bradykinin, serotonin, substance p, norepinephrine, calcitonin gene-related peptide, tumor necrosis factor- a, and interleukin- b were detected in active mftrps, compared to latent mftrps and control subjects without mftrps. the difference was statistically significant (p< . ) despite the small sample size. a persistent barrage of nociceptive signals from mftrps may eventually cause “central sensitization,” a form of neural plasticity involving functional and/or structural change within the dorsal horn of the spinal cord. the sensitized dorsal horn becomes a “neurologic lens,” consolidating other nociceptive signals that converge upon the same segment of the spinal cord, including other somatic dysfunctions and visceral dysfunctions . as a result, post-synaptic spinal neurons exhibit decreased activation thresholds, increased response magnitudes, and increased recruitment of receptive field areas. they fire with increased frequency or fire spontaneously, trans- mitting nociceptive signals to supraspinal sites, such as the thalamus and cerebral cortex. central sensitization may also modulate spinal interneurons and descending inhibitory pathways. central sensitization is symptomati- cally expressed as allodynia (pain to normally non-painful stimuli) and hyperalgesia (abnormally increased sensa- tion of pain). simons, travell, and simons described the central nervous system (cns) as an “integrator” of mftrps, akin to korr’s description of the cns as an “organizer” of somatic dysfunction. autonomic component autonomic phenomena associated with mftrps include localized sweating, vasoconstriction or vasodilation, and pilomotor activity (“goosebumps”) . mftrps located in the head and neck may cause lacrimation, coryza (nasal discharge), and salivation . the autonomic nervous system (ans) is primarily involved in reflex arcs, exerting control of cardiac muscle and smooth muscle in blood vessels, glands, and visceral organs. hubbard and berkoff re- viewed the literature that demonstrated ans involvement in skeletal muscles and mptrp formation. sympathetic neurons innervating vessels in skeletal muscles may exit the perivascular space and terminate among intrafusal fibers within muscle spindles. sympathetic neurons release norepinephrine, a neurotransmitter involved in the “fight-or-flight” response. norepinephrine activates -adrenergic receptors in the intrafusal muscle cell membrane. activation of -adrenergic receptors depresses the feedback control of muscle length, detrimentally affecting motor performance and possibly contributing to the “atp energy crisis” . norepinephrine has been shown to augment the amplitude and duration of mepps in frog leg motor endplates . pentolamine, an antagonist of -adrenergic receptors, decreases sea in mftrps . similar effects have been seen with local intramuscular injections of phenoxybenzamine, another -adrenergic antagonist . the ans may indirectly exacerbate mftrp formation via viscerosomatic reflexes. visceral autonomic afferents from disturbed viscera carry signals to the dorsal horn. chronic input eventually facilitates neurotransmission at that spinal level . this form of central sensitization accelerates in the presence of nociceptor aigs and ep- haptic crosstalk with neighboring autonomic nerves . ephaptic crosstalk (cross-excitation) is the nonsynaptic interaction between two nerves that are parallel and relatively close together so that their action potentials influence each other. translating theory to therapy the motor endplate and “atp energy crisis” hypoth- eses have changed our approach to treating mftrps. for example, the edition of myofascial pain and dysfunction: the trigger point manual , abandoned the application of heavy ischemic compression upon mftrps. deep digital pressure that produces additional ischemia is not beneficial. instead, simons, travell, and simons recommended applying gentle digital pressure to mftrps to avoid exacerbating tissue hypoxia. they named their technique ‘”trigger point pressure release.” a single finger pad palpates the mftrp while the affected muscle is pas- sively lengthened to a point of tissue resistance. next, the mftrp is pressed with slowly increasing pressure until the palpating finger encounters a barrier (local tissue resistance). the engaged barrier is held until a release of tension is palpated. the finger “follows” the released tissue by taking up tissue slack, engaging a new barrier, and repeating the sequence. this “press and stretch” is believed to restore abnormally contracted sarcomeres to their normal resting length. we hypothesize that “press and stretch” mechanically uncouples myosin from actin, a process that normally requires atp, so that the technique reduces atp demand and breaks the energy crisis cycle. press and stretch may also help release the “stuck” spring function of the titin connection to the z bands within sarcomeres. simons, travell, and simons’ new manual also em- phasized the relationship between mftrps and nearby / the journal of manual & manipulative therapy, articular dysfunctions. they correlated suboccipital mftrps with occipito-atlantal dysfunction, semispinalis capitus mftrps with occipito-atlantal and atlanto-axial dysfunctions, and splenius mftrps with upper thoracic articular dysfunctions . this close association between mftrps and articular dysfunctions is the result of a positive feedback loop. lewit has emphasized this close association in several publications , . a mftrp in a muscle that crosses an articulation reduces this articulation’s full range of motion, and the mftrp taut band exerts continuous compression upon the articula- tion. soft tissues surrounding the articulation cannot withstand chronic compression or tension, and they respond with increased sensitivity. when sufficiently sensitized, these structures send continuous nociceptive messages to the central nervous system, which responds by further activation of mftrps, which in turn increases the muscle tension. this positive feedback loop aggra- vates the articular distress. articular dysfunctions can be treated directly by muscle energy technique (similar to contract-relax or post-isometric relaxation techniques), joint mobilization, and high-velocity, low-amplitude thrust techniques. articular dysfunctions can be treated indirectly with techniques that address dysfunctional muscles or fascia that cross the articulations, such as strain-counterstrain and myofascial release. indications and precautions for these techniques are the same as with any articular dysfunctions. methods for treating mftrps and articular dysfunctions work best when combined with patient education. patient education postural training is paramount. postural disorders often contribute to the perpetuation of mftrps. for example, postural strain of the suboccipital muscles may cause mftrps in these muscles , thus leading to further deterioration in muscle structure and function, including radiating somatic pain and atrophic changes, such as muscle atrophy, fibrosis, and decreased tensile strength . suboccipital muscles contain a high density of proprioceptors , so muscle atrophy leads to a loss in proprioceptive balance and a loss of proprioceptive “gate control” at the dorsal horn. this gives rise to chronic pain syndromes including neck pain and headache . in these patients, proprioceptive exercises can be very helpful, such as close-eyed balance training. biomechanical factors that stress muscles, such as repetitive activities, must be avoided. biomechanical stress of a cold muscle is a key factor in the formation of mftrps . cooling the muscle apparently upregulates nachr activity at the motor endplate . patients with mftrps should avoid excess coffee ; caffeine up-regulates the motor endplate by acting as a ryanodine receptor agonist . tobacco should also be avoided, as nicotine upregulates l-type vsccs and nachr expression, which may lead to muscle hyperexcitability . nicotine activates nachrs in the cns and autonomic nerves. although nachrs in motor endplates are not normally activated by nicotine, mutational defects may sensitize motor endplate nachrs. one study indicated that ethanol also facilitates motor-end plate activity, via a presynaptic mechanism . simons, travell, and simons recommended a diet adequate in vitamins and minerals for the prevention of mftrps. amazingly, in the + years since that recom- mendation, no well-designed study has been published concerning the effects of vitamin supplementation upon mftrps. however, a wealth of clinical experience suggests that low-normal and subnormal levels of vita- mins and minerals act as strong perpetuating factors of mftrps. many case histories attest to patients who responded weakly to manual and/or injection treatment, but adequate supplementation (the return of blood vitamin levels to within mid-normal range) brought about an effective response to the same treatment and with continued supplementation, the patients had no relapse. interestingly, in two cases, a va hospital physi- cian advised discontinuation of “unnecessary” vitamin supplements, and within a few months the patients re- turned to the myofascial pain clinic with active mftrps as before. reinstatement of their supplement regimen and a replication of previous treatment restored their health (simons, unpublished data). similarly, anemia is a perpetuating factor of mftrps that must be corrected to achieve lasting results from treatment . inadequate hemoglobin perpetuates the hypoxia present in mftrps . the importance of calcium and magnesium for normal muscle function is well documented, and trace elements are well known to be essential for many body functions including muscle function. supplementing the diet with phosphatidyl choline has been recommended for the treatment of fibromyalgia , but this may actually provoke mftrps in some patients. choline is a percur- sor to ach, and a nachr gain-of-function mutation may enable choline to directly activate the mutated recep- tors . high doses of phosphatidyl choline are found in supplements containing lecithin, with lower amounts in raw egg yoke, organ meats, soybeans, peanuts, wheat germ, and brewer’s yeast. an estimated % of patients with chronic muscu- loskeletal pain take herbal remedies, so it behooves all health practitioners to understand the mechanisms of herbal medicines . clinical experience has shown that myofascial pain can be improved with many herbal rem- edies and essential oils , including lavender (lavandula angustifolia), lemon balm (melissa officinalis), rosemary (rosmarinus officinalis), kava kava (piper methysticum), skullcap (scutellaria lateriflora), passionflower (passiflora incarnata), rose (rosa species), and valerian (valeriana officinalis). nearly all these herbs contain linalool, a monoterpene that inhibits ach release (a presynaptic mechanism) and nachrs (a postsynaptic mechanism) . myofascial trigger points: translating molecular theory into manual therapy / marijuana (cannabis species) also produces linalool, although the herb’s efficacy may be due to tetrahydro- cannabinol (thc), which inhibits p/q-, n-, and l-type vsccs via cannabinoid receptors found in the motor endplate . sativex, a standardized extract dispensed as an oromucosal spray, has been approved for the treat- ment of muscle spasticity and pain in canada . thc works by mimicking an endogenous neurotransmitter named anandamide . anandamide and thc bind to the same neuroreceptor, known as the cannabinoid receptor. enhanced release of “endocannabinoids” may be one of the mechanisms of osteopathic manipulative treatment , parallel to the effects of manipulative treatment upon serum endorphin levels . getting to the point needling may be necessary to inactivate mftrps. the “motor endplate hypothesis” led to the injection of mftrps with botulinum toxin type a (botoxa), which blocks ach release . a variety of vscc blockers have also been injected. recall that p/q-type and l-type vsccs are the primary pre- and post-synaptic ca + chan- nels (respectively) in normal adult motor endplates. the p/q-specific antagonist omega-agatoxin iva (also known as omega-conotoxin gviic) has shown promise in rat studies , while verapamil, a l-type vscc blocker, reduced mftrp excitability in rabbits . the drug had no effect on mepp (a presynaptic measure), but it decreased post-synaptic currents . thus, verapamil may function as a nachr antagonist, rather than by way of its known vscc antagonism. similarly, quinidine, another l-type antagonist, also downregulates nachrs and may restore ache activity . diltiazem also merits investigation. this l-type ca + channel blocker corrects myopathies caused by defects in ache activity . however, nifedipine, yet another l-type antagonist, unexpectedly increased ach activity at motor endplates, due to a unique effect upon ryanodine-sensitive intracellular ca + stores . hence, research with vscc blockers has generated conflicting results, and recent clinical trials with botoxa have produced mixed results . dry needling is usually as ef- fective as injecting anything; if the procedure elicits a local twitch response, dry needling should be as effective as botox and much less expensive. some nachr antagonists and channel blockers can directly penetrate skin, so they need not be injected. lidocaine patches have recently been suggested . as cited by simons et al , simons, travell, and simons in recommended dimethisoquin ointment (quotane ) for massaging mftrps in superficial muscles such as the orbicularis oculi, frontalis, and occipitalis. dimethisoquin, a local anesthetic, inhibits voltage-gated na+ channels (conferring its anaesthetic effect), but it also acts as an nachr antagonist . its potency is much greater than lidocaine and procaine, and dimethisoquin is uniquely selective for the motor endplate nachr subtype. massage with capsaicin cream (available over the counter as a . % cream) is useful for treating mftrps located in surgical scars , which are particularly refractory to treatment . this seems contra-intuitive: capsaicin is the primary active ingredient in hot peppers, and it activates the vanilloid receptor (trpv ) in nociceptors. however, with repeated exposure to capsaicin, trpv receptors become desensitized, which explains the seemingly paradoxical use of capsaicin as an analgesic . another “massage” treatment of mftrps uses frequency specific micro-current (fsm), which delivers electromagnetic currents through graphite-conducting gloves. in relation to the mftrp “energy crisis” model, studies have shown that fsm increases atp production in muscle tissues as well as reducing cytokine levels . to successfully treat mftrps with fsm, a clinician must be skillful at finding mftrps. conclusion the mftrp, according to our working hypothesis, centers upon dysregulated motor endplates, sustained by a neural loop of sensory afferents and autonomic effer- ents. the resulting “atp energy crisis” links with a spinal reflex disorder known as central sensitization. treatment must simultaneously address the symptomatic trigger points and their underlying causes. appropriate treat- ment includes dry needling (also know as acupuncture), vapocoolant spray-and-stretch, and thermal treatment (including ultrasound and infrared laser), some of which are discussed in other articles presented in this jmmt series. new approaches described in this article, includ- ing manual techniques (“press-and-stretch” and articular methods) patient education, and ach- or vscc-attenuation techniques (e.g., medications, herbs, and nutrition), have evolved from our new etiological concepts. references . simons dg, travell jg, simons ls. travell and simons’ myofas- cial pain and dysfunction: the trigger point manual. volume : upper half of body. nd ed. 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	methods 	electrode insertion 	measurement techniques 	emg analysis 	statistical analysis 	results 	snip and raw emg of scalene and sternocieldomastoid 	relationship between increasing snip and neck muscle moving average emg 	impact of posture on snip and neck muscle emg 	relationship between snip and ta emg activity 	discussion 	validity of snip values 	sniff measurement of inspiratory muscle strength 	activity of respiratory muscles during sniff 	acknowledgements 	references 	gerwin et al expansion simons .pdf 	an expansion of simons’ integrated hypothesis of trigger point formation 	an expansion of simons’ integrated hypothesis of trigger point formation 	robert 	robert 	d. 	gerwin, 	md*, 	jan 	dommerholt, 	pt, mps, and 	jay 	p. 	shah, 	md 	address 	address 	*johns hopkins university, 	*johns hopkins university, 	pain and rehabilitation medicine, 	 old georgetown road, suite c- , 	bethesda, 	md 	 - , 	usa. 	e-mail: gerwin@painpoints.com 	current pain and headache reports 	current pain and headache reports 	 , 	current science inc. issn 	copyright © by current science inc. 	<table> 	<table body> 	<table row> 	simons’ integrated hypothesis proposed a model of trigger point (trp) activation to explain known... 	introduction 	introduction 	myofascial pain syndrome (mps) is a myalgic condition characterized by local and referred pain th... 	local myofascial pain occurs because of the release of substances from damaged muscle, such as ad... 	this article presents known data about the trp and discusses in detail salient features of muscle... 	features of myofascial trigger points and muscle nociceptors 	features of myofascial trigger points and muscle nociceptors 	certain features of the myofascial trp relevant to the problem of how the taut band develops and ... 	a taut muscle band may contain a latent trp, without tenderness. however, in mps, tenderness is a... 	a marked increase in the frequency of low-voltage ( – microvolts) electrical activity is fou... 	areas of intense focal sarcomere contraction have been described in the muscles of animals with n... 	there are a number of biochemical alterations identified by microdialysis sampling techniques at ... 	exercise under ischemic conditions [ 	tendon organs (sensory receptors located at the muscle -tendon junction in skeletal muscle) are r... 	intramuscular hypoperfusion is likely to occur in myalgic syndromes such as myofascial pain [ 	hypoxia (extremely low po 	individuals with work-related trapezius myalgia have a deficit of cytochrome c oxidase [ 	a 	a 	muscle nociceptors are dynamic structures whose receptors can undergo conformational change depen... 	the nociceptor terminal contains stored substances, ( 	implications 	implications 	taken together, these points suggest that a possible activating event in mps is exercise under co... 	the increase in cgrp that occurs in ischemia-induced muscle injury could result in an apparent in... 	the work of shah 	muscle injury related to eccentric muscle contraction and maximal concentric muscle contraction 	muscle injury related to eccentric muscle contraction and maximal concentric muscle contraction 	unaccustomed or intense exercise-induced weakness and muscle damage is well documented, particula... 	eccentric exercise is associated with muscle soreness and muscle damage. immediate injurious effe... 	muscle fiber injury occurs rapidly in eccentric muscle contraction. desmin is a muscle cytoskelet... 	the regions of sarcomere disruption are thought to act as foci for further damage with repeated, ... 	one result of muscle damage is an immediate reduction of muscle force-generating capacity [ 	calcitonin gene-related peptide, acetylcholine receptors, and acetylcholinesterase 	calcitonin gene-related peptide, acetylcholine receptors, and acetylcholinesterase 	calcitonin gene-related peptide 	calcitonin gene-related peptide 	calcitonin gene-related peptide coexists with ach at the synaptic endings of the motor nerve and ... 	calcitonin gene-related peptide receptors consist of protein complexes that span the membrane and... 	calcitonin gene-related peptide increases the contractile force of nerve-induced muscle contracti... 	calcitonin gene-related peptide increases or decreases ach release from motor nerve terminals as ... 	acetylcholine receptors 	acetylcholine receptors 	the achr is a transmembrane complex that has an outer ligand-binding configuration, an intramembr... 	when the achr is activated, ionic channel currents are generated that result in miniature endplat... 	acetylcholine release 	acetylcholine release 	acetylcholine release is quantal and nonquantal. quantal release is calcium-dependent whereas non... 	muscle contraction takes place through depolarization of the muscle fiber membrane at the motor e... 	acetylcholine also acts through a feedback mechanism to regulate its own release at the neuromusc... 	presynaptic sympathetic nerve modulation of acetylcholine release 	presynaptic sympathetic nerve modulation of acetylcholine release 	the sympathetic nervous system modulated the observed endplate noise at the trp, reducing it by a... 	acetylcholinesterase 	acetylcholinesterase 	acetylcholinesterase is present in the synaptic cleft. it breaks down ach and thereby can inhibit... 	acidic ph and muscle pain 	acidic ph and muscle pain 	the work of sluka 	<table> 	<table body> 	<table row> 	<table row> 	<table row> 	figure . a schematic outline of the expanded trigger point hypothesis. the activating event is ... 	figure . a schematic outline of the expanded trigger point hypothesis. the activating event is ... 	hypothesis 	hypothesis 	it can be hypothesized that the activating event in the development of the trp is the performance... 	conclusions 	conclusions 	there normally is an equilibrium between the release of ach, the breakdown of ach, and its remova... 	references and recommended reading 	references and recommended reading 	papers of particular interest, published recently, have been highlighted as: 	papers of particular interest, published recently, have been highlighted as: 	• of importance 	•• of major importance 	 . •• simons 	 . •• simons 	 . •• simons 	dg, 	travell 	jg, 	simons 	ls: 	myofascial pain and dysfunction: the trigger point manual, 	vol , 	edn . 	baltimore: williams and wilkins; 	 . 	this is the authoritative work in the field. it contains the most comprehensive introduction to m... 	 . reinohl 	 . reinohl 	 . reinohl 	j, 	hoheisel 	u, 	unger 	t, 	mense 	s: 	adenosine triphosphate as a stimulant for nociceptive and non- nociceptive muscle group iv recept... 	neurosci lett 	 , 	 : 	 – 	 . 	 . • hubbard 	 . • hubbard 	 . • hubbard 	dr, 	berkoff 	gm: 	myofascial trigger points show spontaneous needle emg activity. 	spine 	 , 	 : 	 – 	 . 	an article of historic interest. hubbard and berkoff first published studies showing the increase... 	 . hong 	 . hong 	 . hong 	cz, 	yu 	j: 	spontaneous electrical activity of rabbit 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acetylcholinesterase and on the f... 	 . sluka 	 . sluka 	 . sluka 	ka, 	price 	mp, 	breese 	nm, 	et al. 	myofascial dysfunction pelvis jarrell.pdf 	myofascial dysfunction in the pelvis 	myofascial dysfunction in the pelvis 	john 	john 	jarrell, 	md, msc 	address 	address 	department of obstetrics and gynecology, 	department of obstetrics and gynecology, 	university of calgary, 	 th street n.w., 	calgary, ab, 	canada 	t n t . 	e-mail: john.jarrell@calgaryhealthregion.ca 	current pain and headache reports 	current pain and headache reports 	 , 	current science inc. issn 	copyright © by current science inc. 	<table> 	<table body> 	<table row> 	chronic pelvic pain is a potentially devastating condition that affects many women with severe co... 	introduction 	introduction 	chronic pelvic pain in women is defined as persistent pain in the pelvic region that has been pre... 	the causes of the condition are poorly understood for many reasons. initial studies of the causes... 	the exact prevalence is unknown. alberta health and wellness reported the presence of chronic pai... 	the spectrum of diseases that have been associated with chronic pelvic pain are manifold. they in... 	a further confounding problem in addition to depression and poor social interactions has been an ... 	common visceral conditions associated with chronic pelvic pain observed at laparoscopy 	common visceral conditions associated with chronic pelvic pain observed at laparoscopy 	endometriosis is a degenerative condition that commonly acts like a benign tumor because of its l... 	adhesions are areas of tissue growth that cause the union of tissues that usually are free of one... 	at laparoscopy, the presence of endometriosis and adhesions make up most of the diagnoses of cond... 	myofascial dysfunction: the great pretender 	myofascial dysfunction: the great pretender 	myofascial dysfunction is an important consideration because it may represent a substantial porti... 	the clinical presentation of the syndrome is the presence of severe tenderness and a nodule or ba... 	the management of myofascial disorders is based on the principle that the vicious cycle can be br... 	approach to the intrapelvic muscles 	approach to the intrapelvic muscles 	there is a significant muscular composition to the pelvis. the major muscles include the levator ... 	examination of patients with chronic pelvic pain should be modified to eliminate the possibility ... 	<table> 	table . clinical characteristics of subjects 	<table heading> 	<table row> 	age 	gravida 	para 	number 	duration, y 	<table body> 	<table row> 	number 	 	 	 	 	 	<table row> 	mean 	 	 	 . 	 . 	 . 	<table row> 	minimum 	 	 	 	 	 . 	<table row> 	maximum 	 	 	 	 	 	<table row> 	standard deviation 	 . 	 . 	 . 	 . 	 . 	the approach to the treatment of these bands is as presented by gerwin [ 	as in abdominal wall problems, one must be cautious in the simple treatment of the trigger points... 	cross-sectional study of patients with pelvic pain and myofascial dysfunction 	cross-sectional study of patients with pelvic pain and myofascial dysfunction 	just as it is important not to miss muscle pain in the clinical evaluation of the abdomen and pel... 	<table> 	<table body> 	<table row> 	<table row> 	<table row> 	figure . the relationship of age and the number of myofascial trigger points identified. 	figure . the relationship of age and the number of myofascial trigger points identified. 	in this analysis, the number of trigger points was found to range from one to nine. the duration ... 	in this limited study, the presence or absence of a trigger point in the abdominal wall was a ver... 	<table> 	table . presence of visceral disease among subjects with abdominal wall trigger points 	<table heading> 	<table row> 	visceral disease 	positive 	negative 	<table row> 	tender point 	positive 	negative 	total 	predictive value 	predictive value 	<table body> 	<table row> 	present 	 	 	 	<table row> 	absent 	 	 	 	 . 	<table row> 	 	 	 	 . 	<table row> 	sensitivity 	 . 	<table row> 	specificity 	 . 	<table row> 	prevalence 	 . 	furthermore, there was an interesting observation that the actual number of trigger points that c... 	conclusions 	conclusions 	this study was done to determine if the link between myofascial dysfunction and visceral disease ... 	the processes of myofascial dysfunction appear somewhat dynamic on the basis that there are age-r... 	the relationship of abdominal wall trigger points and visceral disease is of interest because it ... 	from a clinical perspective, this study is relevant to the management of myofascial dysfunction. ... 	references and recommended reading 	references and recommended reading 	papers of particular interest, published recently, have been highlighted as: 	papers of particular interest, published recently, have been highlighted as: 	• of importance 	•• of major importance 	 . •• steege 	 . •• steege 	 . •• steege 	jf, 	metzger 	da. 	chronic pelvic pain, 	edn . 	philadelphia: 	wb saunders company; 	 . 	the current standard for a comprehensive but readable text of a complex societal and medical prob... 	 . health surveillance alberta health and wellness ea: 	 . health surveillance alberta health and wellness ea: 	 . health surveillance alberta health and wellness ea: 	chronic pain in alberta: a portrait from the national population health survey and the ... 	http://www.health.gov.ab.ca/public/diseases/pdf/chronicpainreport.pdf 	. accessed may , . 	 . mathias 	 . mathias 	 . mathias 	sd, 	kupperman 	m, 	lieberman 	rf, 	et al. 	 . olive 	 . olive 	 . olive 	dl, 	pritts 	ea: 	the treatment of endometriosis: a review of the evidence. 	ann n y acad sci 	 , 	 : 	 – 	 . 	 . schroeder 	 . schroeder 	 . schroeder 	ak, 	diedrich 	k, 	ludwig 	m: 	medical management of endometriosis. 	drugs 	 , 	 : 	 – 	 . 	 . wenzyl 	 . wenzyl 	 . wenzyl 	r, 	kiesel 	l, 	huber 	jc, 	wieser 	f: 	endometriosis: a genetic disease. 	drugs today (barc) 	 , 	 : 	 – 	 . 	 . bischoff 	 . bischoff 	 . bischoff 	fz, 	simpson 	jl. 	heritability and molecular genetic studies of endometriosis. 	hum reprod update 	 , 	 : 	 – 	 . 	 . barbieri 	 . barbieri 	 . barbieri 	rl: 	etiology and epidemiology of endometriosis. 	am j obstet gynecol 	 , 	 : 	 – 	 . 	 . sampson 	 . sampson 	 . sampson 	ja: 	perforating hemorrhagic (chocolate) cysts of the ovary. 	arch surg 	 , 	 : 	 – 	 . 	 . sampson 	 . sampson 	 . sampson 	ja: 	ovarian hematomas of endometrial type (perforating hemorrhagic cysts of the ovary) and implantati... 	boston med surg j 	 , 	 : 	 . 	 . redwine 	 . redwine 	 . redwine 	db: 	was sampson wrong? 	fertil steril 	 , 	 : 	 – 	 . 	 . paul 	 . paul 	 . paul 	dw, 	braun 	dp: 	immunology of endometriosis. 	best pract res clin obstet gynaecol 	 , 	 : 	 – 	 . 	 . rier 	 . rier 	 . rier 	se: 	the potential role of exposure to environmental toxicants in the pathophysiology of endometriosis. 	ann n y acad sci 	 , 	 : 	 – 	 . 	 . rier 	 . rier 	 . rier 	se, 	turner 	we, 	martin 	dc, 	et al. 	 . de felip 	 . de felip 	 . de felip 	e, 	porpora 	mg, 	di domenico 	a, 	et al. 	 . guo 	 . guo 	 . guo 	sw: 	the link between exposure to dioxin and endometriosis: a critical reappraisal of primate data. 	gynecol obstet invest 	 , 	 : 	 – 	 . 	 . simons 	 . simons 	 . simons 	dg: 	the nature of myofascial trigger points. 	clin j pain 	 , 	 : 	 – 	 . 	 . gerwin 	 . gerwin 	 . gerwin 	rd: 	neurobiology of the myofascial trigger point. 	baillieres clin rheumatol 	 , 	 : 	 – 	 . 	 . • gerwin 	 . • gerwin 	 . • gerwin 	rd: 	classification, epidemiology, and natural history of myofascial pain syndrome. 	curr pain headache rep 	 , 	 : 	 – 	 . 	gerwin's description of myofascial disorders is a helpful reference when applied to the pelvic mu... 	 . travell 	 . travell 	 . travell 	jg, 	simons 	dg: 	myofascial pain and dysfunction: the trigger point manual. 	baltimore: 	williams and wilkins; 	 . 	 .cnp.itoh.pdf 	randomised trial of trigger point acupuncture compared with other acupuncture for treatment of chronic neck pain 	introduction 	methods 	patients 	design 	blinding 	treatment 	standard acupuncture (sa) group 	trigger point acupuncture (trp) or non-trigger point (non-trp) group 	sham acupuncture (sh) group 	evaluation 	assessment of blinding technique 	statistical analysis 	results 	patient characteristics 	vas score 	functional impairment 	assessment of the blinding technique 	discussion 	effectiveness of the trigger point as a treatment site of acupuncture 	acknowledgments 	references 	chen-elastography-mri- .pdf 	identification and quantification of myofascial taut bands with magnetic resonance elastography 	methods 	bovine gel phantom 	finite element simulation 	participants 	results 	taut band phantom 	finite element simulation 	participants 	discussion 	study limitations 	conclusions 	references 	chen et al elastography .pdf 	ability of magnetic resonance elastography to assess taut bands 	introduction 	methods 	magnetic resonance elastography on bovine gel phantom 	finite element modeling 	magnetic resonance elastography on human subjects 	results 	magnetic resonance elastography on bovine gel phantom 	finite element simulation 	magnetic resonance elastography on human subjects 	discussion 	acknowledgments 	references 	shah et al review jbmt.pdf 	uncovering the biochemical milieu of myofascial trigger points using in vivo microdialysis: an application of muscle pain concepts to myofascial pain syndrome 	introduction 	historical terminology 	myofascial trigger point diagnostic criteria 	motor abnormalities of the myofascial trigger point 	electrophysiology 	the integrated trigger point hypothesis 	the cinderella hypothesis 	sensory abnormalities of the myofascial trigger point 	nociceptor properties 	chemical activation of afferent nerves 	peripheral and central sensitization 	uncovering the biochemical milieu of myofascial trigger points 	microdialysis sampling of the trapezius 	microdialysis sampling of the trapezius and gastrocnemius 	roles of biochemical substances associated with pain and inflammation 	ph 	neuropeptides 	catecholamines 	cytokines 	conclusion 	references 	chang chen chang neuroaxonal degeneration.pdf 	evidence of neuroaxonal degeneration in myofascial pain syndrome: a study of neuromuscular jitter by axonal microstimulation 	introduction 	subjects and methods 	patients profile 	stimulated sfemg study 	statistical analysis 	results 	discussion 	acknowledgements 	references 	ge et al topography trp .pdf 	topographical mapping and mechanical pain sensitivity of myofascial trigger points in the infraspinatus muscle 	introduction 	materials and methods 	patients 	experimental protocol 	assessment of muscle mechanical pain sensitivity 	topographical ppt mapping 	dry needling procedure 	statistical analysis 	results 	the number of mtrps bilaterally in the infraspinatus muscles 	ppt bilaterally in the infraspinatus 	location of mtrps bilaterally in the infraspinatus muscles 	discussion 	multiple active mtrps are associated with unilateral shoulder pain 	presence of latent mtrps bilaterally in the infraspinatus 	peripheral sensitization is crucial to the development of myofascial pain syndrome 	references 	ge et al induction of muscle cramps and latent mtrp exp brain res.pdf 	induction of muscle cramps by nociceptive stimulation of latent myofascial trigger points 	abstract 	introduction 	materials and methods 	subjects 	experimental protocol 	emg-guided intramuscular injection 	emg-guided injection needle recordings 	muscle cramp as dewned by emg 	assessment of local muscle pain intensity 	statistical analysis 	results 	pain intensity 	emg activity before and after glutamate and isotonic saline injections 	occurrence of muscle cramps 	discussion 	association of muscle cramps with mtrps 	increased nociceptive sensitivity at mtrps mediates the occurrence of muscle cramps 	references 	ge sympathetic facilitation.pdf 	sympathetic facilitation of hyperalgesia evoked from myofascial tender and trigger points in patients with unilateral shoulder pain 	introduction 	subjects and methods 	subjects 	experimental protocol 	measurement of ppt and ptrp 	statistical analysis 	results 	effect of increased sympathetic activity on ppt at the tender and trigger points 	effect of increased sympathetic activity on ppt in the tibialis anterior muscle 	effect of increased sympathetic activity on ppt, referred pain threshold (ptrp), and local and referred pain intensities at the trigger point 	discussion 	sympathetic hyperactivity at myofascial tender and trigger points 	sympathetic hyperactivity and referred muscle pain 	acknowledgements 	references 	giamberardino trp and migraines.pdf 	contribution of myofascial trigger points to migraine symptoms 	materials and methods 	phase : main experiment 	patients and subjects 	experimental procedures 	palpation of cervical muscles for trigger point assessment 	pain thresholds and trp treatment 	migraine parameters 	technique of pain threshold measurement to electrical stimulation 	cutaneous thresholds in migraine sites of patients without active cervical trigger points 	trp infiltration technique 	phase : secondary experiment 	statistical analysis 	results 	phase : main experiment 	pain thresholds 	cutaneous thresholds in migraine sites of patients without active cervical trigger points 	migraine parameters 	pain thresholds versus migraine parameters in treated patients 	phase : secondary experiment 	pain thresholds 	migraine parameters 	discussion 	acknowledgments 	references 	pathogenesis of muscle pain mense.pdf 	the pathogenesis of muscle pain 	the pathogenesis of muscle pain 	siegfried 	siegfried 	mense, 	md 	address 	address 	institut für anatomie und zellbiologie iii, universität heidelberg, 	institut für anatomie und zellbiologie iii, universität heidelberg, 	im neuenheimer feld , 	 	heidelberg, 	germany. 	e-mail: mense@urz.uni-heidelberg.de 	current pain and headache reports 	current pain and headache reports 	 , 	current science inc. issn 	copyright © by current science inc. 	<table> 	<table body> 	<table row> 	nociceptive nerve endings in muscles and other tissues are equipped with a multitude of receptor ... 	introduction 	introduction 	in recent years, it has become more obvious that muscle pain differs in several aspects from cuta... 	this article focuses on peripheral and central nervous mechanisms of muscle pain and discusses pa... 	peripheral mechanisms 	peripheral mechanisms 	neurobiology of muscle nociceptors 	neurobiology of muscle nociceptors 	the term neurobiology includes neurophysiologic and neuroanatomic aspects. morphologically, a no... 	recordings of the electrical activity of single muscle afferent fibers in cats and rats have show... 	well-known stimulants for muscle nociceptors are endogenous pain-producing substances such as bra... 	this type of nociceptor would be well suited to mediate the pain of tonic muscle contractions, wh... 	<table> 	<table body> 	<table row> 	figure . schematic drawing of a nociceptive nerve ending showing membrane receptor molecules an... 	figure . schematic drawing of a nociceptive nerve ending showing membrane receptor molecules an... 	data from nociceptors in joints and other tissues have shown that the previously mentioned endoge... 	receptor molecules for clinical cases of muscle pain are the so-called purinergic receptors ( 	another receptor molecule of particular clinical interest is vr- . it responds to an increase in ... 	<table> 	<table body> 	<table row> 	<table row> 	<table row> 	figure . proportion of rat muscle nociceptors that responded to adenosine triphosphate (atp), ... 	figure . proportion of rat muscle nociceptors that responded to adenosine triphosphate (atp), ... 	in experiments by the author’s group, atp and acidic solutions were effective stimulants for musc... 	theoretically, the pain during tooth clenching, bruxism, and tension-type headache could be media... 	neuropeptide content of muscle nociceptors 	neuropeptide content of muscle nociceptors 	there is no neuropeptide that can be regarded as specific for sensory fibers from muscle or for m... 	interactions between stimulants at the receptive nerve ending 	interactions between stimulants at the receptive nerve ending 	prostaglandin e 	the concentration of pg e 	sensitization of nociceptors as the peripheral neurophysiologic basis of tenderness and hyperalgesia 	sensitization of nociceptors as the peripheral neurophysiologic basis of tenderness and hyperalgesia 	many substances released from pathologically altered tissue increase the mechanical sensitivity o... 	<table> 	<table body> 	<table row> 	figure . expansion of the spinal target area of the gastrocnemius-soleus (gs) muscle nerves aft... 	figure . expansion of the spinal target area of the gastrocnemius-soleus (gs) muscle nerves aft... 	longer-lasting pathologic alterations of muscle tissue sensitize nociceptors and increase the inn... 	mechanisms of muscle pain at the spinal level 	mechanisms of muscle pain at the spinal level 	myositis-induced neuroplastic changes in the spinal dorsal horn 	myositis-induced neuroplastic changes in the spinal dorsal horn 	input from peripheral nociceptors to the spinal cord or brain stem is known to lead to changes in... 	the cellular mechanism underlying the myositis- induced expansion of the responding neuron popula... 	neurotransmitters involved in central sensitization 	neurotransmitters involved in central sensitization 	experiments with intrathecal administration of antagonists to sp and nmda receptors showed that t... 	patients with myositis complain of hyperalgesia, hyper aesthesia, spontaneous pain, and dysaesthe... 	mechanism of referral of muscle pain 	mechanism of referral of muscle pain 	the expansion of the input region of the inflamed gs muscle nerve likely underlies the spread an... 	the transition from acute to chronic muscle pain 	the transition from acute to chronic muscle pain 	the functional reorganization in the spinal dorsal horn is an expression of neuroplasticity becau... 	tissue sections from animals with an acute myositis ( - hour duration) showed a significant incr... 	the last step in the transition from acute to chronic muscle pain is morphologic changes in the c... 	in patients, the development of lesion-induced structural changes in the dorsal horn and in highe... 	conclusions 	conclusions 	the data obtained in studies on nociceptive nerve endings in muscle and other tissues show that t... 	the transition from acute to chronic muscle pain is considered to be a series of processes that s... 	references and recommended reading 	references and recommended reading 	papers of particular interest, published recently, have been highlighted as: 	papers of particular interest, published recently, have been highlighted as: 	• of importance 	•• of major importance 	 . • mense 	 . • mense 	 . • mense 	s, 	simons 	dg: 	muscle pain: understanding its nature, diagnosis, and treatment, 	baltimore and london: 	lippincott williams & wilkins; 	 . 	this book addresses all of the known clinical conditions with muscle pain and attempts to give ex... 	 . keay 	 . keay 	 . keay 	ka, 	bandler 	r: 	deep and superficial noxious stimulation increases fos-like immunoreactivity in different regions... 	neurosci lett 	 , 	 : 	 – 	 . 	 . yu 	 . yu 	 . yu 	xm, 	mense 	s: 	response properties and descending control of rat dorsal horn neurons with deep receptive fields. 	 neuroscience 	 , 	 : 	 – 	 . 	 . •• fields 	 . •• fields 	 . •• fields 	hl, 	basbaum 	ai: 	central nervous system mechanisms of pain modulation. 	textbook of pain. 	edited by wall pd, melzack r. 	edinburgh, london, new york: 	churchill livingstone; 	 : 	 – 	 . 	one of the most recent and comprehensive reviews of the descending pain modulating system. 	 . svensson 	 . svensson 	 . svensson 	p, 	minoshima 	s, 	beydoun 	a, 	morrow 	tj: 	cerebral processing of acute skin 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oxide donor in nociception. 	brain res 	 , 	 : 	 – 	 . 	 . de vere 	 . de vere 	 . de vere 	r, 	bradley 	wg: 	polymyositis: its presentation, morbidity, and mortality. 	brain 	 , 	 : 	 – 	 . 	 . ansell 	 . ansell 	 . ansell 	bm: 	management of polymyositis and dermatomyositis. 	clinics in rheumatic diseases . 	london: 	saunders; 	 : 	 – 	 . 	 . • simons 	 . • simons 	 . • simons 	dg, 	travell 	jg, 	simons 	ls: 	travell and simons' myofascial pain and dysfunction: 	the trigger point manual. upper half of body, vol , edn . 	baltimore: 	williams and wilkins; 	 . 	the second edition of the famous trigger point manual. the first volume of the two-volume manual ... 	 . hoheisel 	 . hoheisel 	 . hoheisel 	u, 	unger 	t, 	mense 	s: 	a block of the nitric oxide synthesis leads to increased background activity predominantly in n... 	pain 	 , 	 : 	 – 	 . 	 . sperry 	 . sperry 	 . sperry 	ma, 	goshgarian 	hg: 	ultrastructural changes in the rat phrenic nucleus developing within h after cervical 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row> 	muscle pain can be induced and assessed experimentally by a variety of methods. ischemic and exer... 	introduction 	introduction 	the pain from deep somatic structures represents a major part of pain complaints in patients. dee... 	the neurobiologic mechanisms involved in muscle pain often are difficult to resolve from clinical... 	pain is a multidimensional perception and the reaction to a single standardized stimulus of a giv... 	<table> 	table . assessment methods and quantitative parameters of muscle pain 	<table heading> 	<table row> 	methods 	quantitative parameter 	<table body> 	<table row> 	response-dependent 	intensity 	<table row> 	visual analogue scale 	<table row> 	verbal descriptor scale 	<table row> 	numerical scale 	<table row> 	cross-modality matching 	<table row> 	stimulus-response function 	<table row> 	quality 	<table row> 	mcgill pain questionnaire 	<table row> 	unpleasantness 	<table row> 	visual analogue scale 	<table row> 	distribution 	<table row> 	drawings (area, location) 	<table row> 	stimulus-dependent 	detection threshold (methods of limits/constant stimuli) 	<table row> 	pain threshold (methods of limits/constant stimuli) 	<table row> 	pain tolerance threshold (methods of limits/constant stimuli) 	most experimental pain research has been done on cutaneous pain, although cutaneous pain is far l... 	quantitative assessment of experimental muscle pain 	quantitative assessment of experimental muscle pain 	the assessment methods of muscle pain are based on psychophysical, electrophysiologic, and imagin... 	psychophysical determinations can be divided into response-dependent and stimulus-dependent metho... 	the stimulus-dependent methods are based on the adjustment of the stimulus intensity until a pred... 	stimulus-response functions are more informative than a threshold determination because suprathre... 	<table> 	table . stimulus modalities for induction of experimental muscle pain in humans 	<table heading> 	<table row> 	type 	modality 	stimulus 	<table body> 	<table row> 	endogenous 	ischemia 	tourniquet plus contractions 	<table row> 	exercise 	concentric contractions 	<table row> 	eccentric contractions 	<table row> 	exogenous 	electrical 	intramuscular 	<table row> 	intraneural 	<table row> 	mechanical 	pressure 	<table row> 	tourniquet pressure 	<table row> 	focused ultrasound 	<table row> 	chemical 	hypertonic saline, potassium, levoascorbic acid, capsaicin, bradykinin, serotonin, calcitonin gen... 	<table row> 	thermal 	heated isotonic saline 	<table row> 	(focused ultrasound) 	verbal assessments of the experienced muscle pain intensity and other subjective characteristics ... 	experimental muscle pain 	experimental muscle pain 	various procedures can induce muscle pain and they can be divided into endogenous and exogenous t... 	ischemia 	ischemia 	lewis [ 	exercise 	exercise 	exercise-induced muscle pain by concentric muscle work normally is short lasting and results from... 	electrical 	electrical 	in human studies, intramuscular electrical stimulation can be used to assess the sensitivity of m... 	mechanical 	mechanical 	mechanical, painful stimulation can be achieved with pressure algometers. the most widely used te... 	tender points are anatomically determined soft-tissue body sites. among other criteria, the patie... 	an alternative to pressure algometry, with the inherent variability-related manual application, i... 	chemical 	chemical 	intramuscular injections of algogenic substances have been used to induce human muscle pain [ 	the sensitization of muscle nociceptors is the best established peripheral mechanism for the subj... 	glutamate receptors (ionotropic and metabotropic) are other receptor types that potentially are i... 	svensson 	referral of pain represents a common clinical sign in many musculoskeletal pain disorders and in ... 	experimentally induced referred pain is an important indicator of central sensitization in patien... 	<table> 	<table body> 	<table row> 	<table row> 	<table row> 	figure . assessment of the deep tissue sensitivity by automated pressure algometry. a, pressur... 	figure . assessment of the deep tissue sensitivity by automated pressure algometry. 	the plasticity of the central nervous system also may alter the somatosensory sensitivity and acc... 	other modalities 	other modalities 	from animal studies, afferent recordings have shown that a subgroup of muscle nociceptors respond... 	focused ultrasound has been used to induce muscle, joint, and skin pain [ 	conclusions 	conclusions 	reliable methods for quantitative induction and assessment of muscle pain, referred pain, and sen... 	acknowledgment 	acknowledgment 	the danish technical research council supported the time spent writing this review. 	references and recommended reading 	references and recommended reading 	papers of particular interest, published recently, have been highlighted as: 	papers of particular interest, published recently, have been 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integration of energy, ecology and environment guest editor: bin chen (✉) state key laboratory of water environment simulation, school of environment, beijing normal university, beijing , china © higher education press and springer-verlag berlin heidelberg background the rising concern about global energy crisis and its impact on environment implies a transition from the current development paradigm to a sustainable and desirable one, which remains a significant challenge for scientists, industries and governments to make reasonable energy and environmental policies to save energy and reduce environmental impact as well as carbon emission during the managing and controlling process at each level of the concerned systems. a special issue of frontiers of earth science is therefore established to be dedicated to the integration of energy, ecology and environmental problems. we invited investigators from universities, institutes and governments to contribute original research articles as well as review articles that can advance our understanding of the interactions between the energy system and biophysical environment in the context of ecology, economic and society at local, national and international levels. papers in this issue these papers cover a variety of overlapping and transdisciplinary areas, including integration of energy and ecology, ecology and environment, and environment and energy issues. . integration of energy and ecology issues voinov and filatova (p –p ) presented an explorative model that demonstrates that a smooth transition from an oil- based economy to alternative energy sources is possible only if it is started well in advance while fossil resources are still abundant. two transparent and flexible methods of pricing were also suggested to eliminate price externalities on energy resources, which may help stimulate less consumption and can smooth the transition to renewable energy. chen s h et al. (p –p ) studied the response of energy partition to land use using the noah model. the trend of the response of sensible heat flux (shf) and latent heat flux (lhf) to the land use change (luc) over three typical ecological zones in china is originally quantified using the noah results for foreknowing the partition status of the net radiant energy (nre) in land-atmosphere interaction. to present a systematic evaluation framework for urban ecosystem, ji et al. (p –p ) constructed new evaluation indicators, based on the concepts of embodied energy and embodied carbon emissions, which take both the immediate and indirect effects of energy consumption and emissions into account. with a case study of beijing ecosystem, conventional evaluation indicators were compared with the newly constructed ones. results show that the energy consumption and emissions of urban industries are described better by the new indicators, which may provide useful information for urban ecosystem structure optimization. considering that objective expression of ecosystems is an urgent concern in sustainable ecosystem management, nguyen et al. (p –p ) combined the community information measurements such as shannon index and exergy and their variance formulas to assess the ecological integrity and thereby provided extra scopes of structural and functional properties in communities in response to natural variability and anthropogenic disturbance. the proposed method was also recommended as a suitable reference system for assessment of the health of received december , e-mail: chenb@bnu.edu.cn front. earth sci. , ( ): – doi . /s - - -z aquatic ecosystems exposed to environmental disturbances. zhang q z et al. (p –p ) characterized two indigenous bacteria of petroleum contaminated soil to utilize diesel fuel as the sole carbon and energy sources, which can be identified to be better than exotic bacterial strains and chemicals for bioremediation of petroleum contaminated sites. . integration of ecology and environment issues chen q w et al. (p –p ) used set pair analysis to study the dry and wet compensation characteristics of water resource parameters, of which the fuzzy membership and grey correlation degree are adopted to test the result of set pair analysis. dong et al. (p –p ) conducted a coupled planning of water resources, in which agricultural land use was undertaken through the development of an inexact-stochastic programming approach. interval linear programming (ilp) and chance-constraint programming (ccp) approaches were integrated into a general framework to tackle uncertainties and complexities expressed as intervals and probabilistic distributions, with a case study of typical regional water resource system in an agricultural watershed. the dongjiang river is taken as an example, with parameters include precipitation and mean discharge from different hydrological stations being analyzed. xu et al. (p –p ) developed an integrated model system by coupling a simple global socio-economic model and regional spatial allocation model, and applied it to the land use system in china. a series of simulations were conducted to demonstrate how the integrated model link global socioeconomic factors with regional land use changes in china. yin et al. (p –p ) analyzed the impacts of climate change and human activities on grassland ecosystem at different spatial and temporal scales. the regression and residual analysis were used based on the data from remote sensing data and meteorological stations to quantify the effects of human activities and climatic factors. a comprehensive review of the international methods used to prioritize chemicals for environmental management was conducted by yu et al. (p –p ), based on which an appropriate screening method was developed to account for the unique characteristics of chemical use within china. the proposed classification method may help decision-makers to prioritize and identify the chemicals with the highest environmental risk, thereby providing a basis for improving chemical management. yuan et al. (p –p ) presented an analytical study of a pulsed volatile contaminant emission into a free- surface wetland flow. an eco-model is given for environmental contaminant transport under the combined action of advection, mass dispersion, apparent reaction, and volatilization at the free water surface. . integration of environment and energy issues chen c et al. (p –p ) introduced the life cycle assessment to calculate the environmental impact loads of different types of energy resources used in urban regions. the proposed evaluation method is also applied to beijing, revealing that photochemical oxidant formation and acidification are the primary impact factors in the life cycle of all energy resources. chen d et al. (p –p ) used emergy to evaluate a pumping irrigation water production system in china. a framework for emergy evaluation of the significance of irrigation water and its production process was developed. guan et al. (p –p ) provided a concrete study to understand the effects of operation on biofilm morphology and microstructure and degradation efficiency for the disposal of sulfur dioxide produced by coal-fired power plants. a flat-panel reactor–membrane bioreactor (mbr) with a composite membrane consisting of a dense layer and a support layer was designed, and the membrane bioreactors inoculated with thiobacillus ferrooxidans were further synthetically analyzed for the removal of sulfur dioxide. embodied exergy-based analysis as an effective approach to achieve a unified and scientific assessment is devised by meng et al. (p –p ) to assess the energy and resource consumption of buildings. a systematic accounting of the landmark buildings in e-town, beijing is performed, on the basis of raw project data in the bill of quantities and the most recent embodied exergy intensities for the chinese economy in with industrial sectors. zhang b et al. (p –p ) also presented an interprovincial input-output embodiment analysis of china’s regional ch emissions in based on the multi-regional input-output table and relevant ch emissions data. comprehensive mitigation measures are suggested to achieve regional ch emission mitigation under consideration of regional transfer of emission responsibility. the guest editor would like to express his high appreciation to the authors and reviewers for their great contribution to this special issue. front. earth sci. , ( ): – << /ascii encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (none) /calrgbprofile (srgb iec - . ) /calcmykprofile (iso coated v % \ eci\ ) /srgbprofile (srgb iec - . ) /cannotembedfontpolicy /error /compatibilitylevel . /compressobjects /off /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /perceptual /detectblends true /detectcurves . /colorconversionstrategy /srgb /dothumbnails true /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel /emitdscwarnings false /endpage - 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/grayimagemindownsampledepth /grayimagedownsamplethreshold . /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /grayimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /jpeg grayacsimagedict << /tilewidth /tileheight /quality >> /jpeg grayimagedict << /tilewidth /tileheight /quality >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution /monoimageminresolutionpolicy /ok /downsamplemonoimages true /monoimagedownsampletype /bicubic /monoimageresolution /monoimagedepth - /monoimagedownsamplethreshold . /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k - >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx acheck false /pdfx check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ . . . . ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ . . . . ] /pdfxoutputintentprofile (none) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org?) /pdfxtrapped /false /syntheticboldness . /description << /enu <feff a f f f e f f c c e d f c f c e e e f e c e e d e e d d > /deu <feff a f f f e f f c c e d f c f f e c e e d e d c d d d c f e e f e c f a f f f f e e e e f d d f e c f e c e f f c f f f f e c e f f c e f c f a f d f e e> >> >> setdistillerparams << /hwresolution [ ] /pagesize [ . . ] >> setpagedevice targeting mitochondrial complex i using bay - reduces melanoma tumor growth research open access targeting mitochondrial complex i using bay - reduces melanoma tumor growth laura schöckel *, andrea glasauer †, farhan basit †, katharina bitschar , hoa truong , gerrit erdmann , carolyn algire , andrea hägebarth , peter hgm willems , charlotte kopitz , werner jh koopman and mélanie héroult abstract background: numerous studies have demonstrated that functional mitochondria are required for tumorigenesis, suggesting that mitochondrial oxidative phosphorylation (oxphos) might be a potential target for cancer therapy. in this study, we investigated the effects of bay - , a small molecule that inhibits the first oxphos enzyme (complex i), in melanoma in vitro and in vivo. results: bay - decreased mitochondrial oxygen consumption and induced partial depolarization of the mitochondrial membrane potential. this was associated with increased reactive oxygen species (ros) levels, lowering of total cellular atp levels, activation of amp-activated protein kinase (ampk), and reduced cell viability. the latter was rescued by the antioxidant vitamin e and high extracellular glucose levels ( mm), indicating the involvement of ros-induced cell death and a dependence on glycolysis for cell survival upon bay - treatment. bay - significantly reduced tumor growth in various braf mutant melanoma mouse xenografts and patient-derived melanoma mouse models. furthermore, we provide evidence that inhibition of mutated braf using the specific small molecule inhibitor vemurafenib increased the oxphos dependency of braf mutant melanoma cells. as a consequence, the combination of both inhibitors augmented the anti-tumor effect of bay - in a braf mutant melanoma mouse xenograft model. conclusions: taken together, our results suggest that complex i inhibition has potential clinical applications as a single agent in melanoma and also might be efficacious in combination with braf inhibitors in the treatment of patients with braf mutant melanoma. keywords: anti-tumor efficacy, mitochondrial complex i, reactive oxygen species (ros), oxidative phosphorylation (oxphos), small molecule inhibitor, braf mutant melanoma, cancer metabolism background it has been well established that cancer cells are character- ized by an altered metabolism compared to normal cells. in fact, cancer cells reprogram their metabolism to meet increased energetic and anabolic needs, including those for atp, reducing equivalents (e.g., nadph), lipids, pro- teins, and nucleotides. the metabolic adaptation of cancer cells enables rapid cell proliferation and sustained cell sur- vival even in extreme tumor microenvironments exhibit- ing hypoxia and nutrient deprivation [ ]. historically, mitochondrial metabolism and oxidative phosphorylation (oxphos) were considered to be expendable for the metabolic demands of rapidly dividing cells [ , ]. this classical observation, made by otto warburg in the s, states that cancer cells convert glucose into lactate even in the presence of sufficiently high oxygen levels. it is now appreciated that mitochondrial metabolism is also pivotal for the generation of building blocks required for cancer cell proliferation and that the “warburg effect” (also known as aerobic glycolysis) does not fully compensate for defects in mitochondrial atp production due to damaged mitochondria as originally proposed. in fact, the majority of cancer cells display functional mitochondria and are able to generate atp through mitochondrial metabolism * correspondence: laura.schoeckel@bayer.com †equal contributors bph, gdd, global therapeutic research group oncology ii, bayer pharma ag, müllerstraße , berlin, germany full list of author information is available at the end of the article cancer & metabolism © schöckel et al. open access this article is distributed under the terms of the creative commons attribution . international license (http://creativecommons.org/licenses/by/ . /), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the creative commons license, and indicate if changes were made. the creative commons public domain dedication waiver (http://creativecommons.org/publicdomain/zero/ . /) applies to the data made available in this article, unless otherwise stated. schöckel et al. cancer & metabolism ( ) : doi . /s - - - http://crossmark.crossref.org/dialog/?doi= . /s - - - &domain=pdf mailto:laura.schoeckel@bayer.com http://creativecommons.org/licenses/by/ . / http://creativecommons.org/publicdomain/zero/ . / fueled by fatty acids and amino acids, such as glutamine [ – ]. additionally, cancer cells also require mitochondrial oxidative metabolism to maintain their redox balance. depending on the cellular context, mitochondria substan- tially contribute to the generation of cellular reactive oxy- gen species (ros). under physiological conditions, ros formation at complex i and iii of the mitochondrial elec- tron transport chain is a natural by-product of mitochon- drial atp generation [ , ] and occurs due to the incomplete reduction of molecular oxygen. specifically in cancer cells, ros appear to play a causal signaling role in tumor development and progression by inducing dna mutations, genetic instability, and also pro- tumorigenic signaling [ ]. when ros production exceeds the capacity of intracellular ros-detoxifying systems, cell-toxic oxidative stress is induced. this explains why cancer cells have to tightly control the bal- ance between ros generation and scavenging in order to remain within the pro-tumorigenic range of ros levels [ ]. in this sense, cancer cells display an in- creased ros scavenging capacity that prevents ros levels from reaching cytotoxic levels incompatible with growth [ , ]. given the important role of oxphos in mitochondrial and cell metabolism, its targeting may be useful in cancer therapy development. the first oxphos complex, com- plex i, constitutes the entry point of electrons and is a known site of ros production [ ]. interestingly, evidence was provided showing that complex i inhibition by the anti-diabetic biguanide metformin inhibits tumorigenesis in vitro and in vivo [ – ]. similarly, the biguanide phen- formin might exert its anti-tumor effects by inhibiting complex i [ ]. however, metformin and phenformin were used at very high concentrations to exert their anti-tumor efficacy, with phenformin also exerting an increased risk of lactic acidosis [ , ]. in this study, we investigated the effects of bay - , a potent and selective small molecule inhibitor of mito- chondrial complex i, on mitochondrial function and anti- tumor activity. bay - has been shown to inhibit hypoxia-inducible factor (hif) gene activation and dis- played anti-tumor activity in an in vivo non-small cell lung cancer xenograft model [ ]. however, the signaling mech- anism by which bay - induced anti-tumorigenic effects is still unclear, and it has not been tested in other cancer models. using braf mutant melanoma as a model system, we here report that bay - -mediated com- plex i inhibition induced melanoma cell death in vitro and reduced melanoma tumor growth in various mouse models in vivo. our results suggest that this effect is medi- ated through bay - -induced stimulation of mito- chondrial ros production, leading to oxidative damage and subsequent cell death. interestingly, we observed that bay - displayed increased anti-tumor efficacy compared to single agent treatment when combined with the small molecule mutant braf inhibitor vemurafenib in nude mice bearing braf mutant melanoma xenografts. methods animal studies and cell cultures tumor xenograft experiments were carried out on female immune-deficient mice in full accordance with the interdisciplinary principles and guidelines for the use of animals in research, marketing and education issued by the new york academy of sciences’ ad hoc committee on animal research. human melanoma sk- mel- and g- cells were subcutaneously inocu- lated in athymic nu/nu mice ( – g, aged – weeks, janvier) and balbc/nude ( – g, aged – weeks, janvier) mice, respectively. a- and lox-imvi mel- anoma cells were inoculated in scid (scid/scid) mice ( – g, aged – weeks, charles river). the melan- oma xenograft mouse model was established by subcutaneous injection into the right flank with . ml sk-mel- cells ( × e ) mixed : with matrigel or . ml a- cells ( . × e ) or lox-imvi cells ( . × e ) mixed : with matrigel or × e g- cells in % matrigel (becton dickinson). mice were randomized into control and treatment groups when tumors reached a size of more than mm . treatment with vemurafenib ( mg/kg/twice daily) or bay - ( mg/kg/day) was administered by oral gavage in ethanol/solutol/water ( / / ). body weight was moni- tored as a measure for treatment related, acute toxicity. tumor areas (measured by caliper) were calculated according to the formula width × length. the human mel- anoma cell lines a- , g- , sk-mel- , sk-mel- , lox-imvi, sk-mel- , ipc- , chl- , and colo- were obtained from american type culture collection (atcc), grown at °c and % co . all cell lines were routinely grown in standard medium recommended by atcc and supplemented with % (v/v) fetal calf serum (fcs, life technologies). when not stated differently, all experiments were carried out in phenol-red-free and pyruvate-free dmem assay medium containing mm glucose (sigma), mm glutamax (gibco), % dialyzed fcs (gibco). western blot analysis melanoma cell lines (a- , g- , sk-mel- , sk-mel- ) were grown to % confluency and incubated with bay - ( nm) or bay - ( nm) in com- bination with either vitamin e ( μm) or nac ( mm) for or h, whereas control samples were treated with an equal volume of dmso. cells were lysed in μl ripa lysis buffer (roche) supplemented with complete protease inhibitor cocktail (roche). lysates were clarified by schöckel et al. cancer & metabolism ( ) : page of centrifugation ( , g, min, °c). the supernatant was transferred to a new tube, and protein levels were quantitated using the bca method (thermo fischer). using sds-page (nu-page – % bis-tris protein gels) and western blotting, – μg total protein were ana- lyzed with the following antibodies: anti-phospho-amp-ac- tivated protein kinase (ampk) (thr ) (cell signaling, # ), anti-ampk (cell signaling, # ), anti-phospho- raptor (ser ) (cell signaling, # ), anti-phospho- p (thr /tyr ) (cell signaling, # ), anti-p (cell signaling, # ), anti-nrf (novus biologicals, nb - ), anti-phospho-erk / (thr /tyr ) (cell sig- naling, # ), anti-erk / (cell signaling, # ), anti- cleaved parp (asp ) (cell signaling, # ), and anti-β-actin (sigma), followed by secondary goat-anti- mouse (irdye cw) or secondary goat-anti-rabbit (irdye lt) antibodies. antibody signals were de- tected and quantitated using a li-cor instrument. analysis of bioenergetics using the seahorse xf extracellular flux analyzer extracellular flux analyses were performed using the seahorse xf extracellular flux analyzer (seahorse bioscience). to determine the effects of vemurafenib, xf tissue culture plates were seeded at , cells/ well. when adherent cells were fully attached, cells were treated with either dmso or vemurafenib ( μm) for h. basal mitochondrial function and mitochondrial stress in response to bay- were measured by oxygen consumption rate (ocr) using the xf mito stress test kit (seahorse bioscience). the xf mito stress test kit reveals key parameters of mitochondrial function: basal respiration, atp production, and re- spiratory capacity. briefly, cells were seeded at equal densities ( , – , cells/well) into xf tissue culture plates. cell media was changed h after cell seeding into unbuffered dulbecco’s modified eagle’s medium (dmem) containing . g/l dmem (sigma), mm glutamax (invitrogen), mm glucose (sigma), . mm nacl (sigma), and adjusted ph to . with naoh. the drug injection ports of the xf assay cartridge were loaded with assay reagents to a final concentration of μm oligomycin, . μm fccp, μm rotenone, and μm antimycin a. ocr and extracellular acidification rate (ecar) were measured under basal conditions and/or after injection of various concentra- tion of bay - following the xf mito stress kit. all treatment conditions were analyzed with six repli- cates. the ocr values were normalized to cell numbers plated. to this end, the cells were stained using cyquant (life technologies) and fluorescence was measured using a microplate reader (tecan) with excitation at nm and emission detection at nm. high-resolution respirometry the culture medium was collected and the braf mutant melanoma cells were trypsinized, washed, and resus- pended to approximately × e cells per ml in the collected culture medium and used to measure cellular oxygen consumption. oxygen consumption was measured at °c using polarographic oxygen sensors in a two- chamber oxygraph (oroboros instruments, innsbruck, austria) as previously described [ ]. briefly, cells were first allowed to respire at basal level for min and then inhibited acutely by a stepwise addition of increasing con- centrations ( – nm) of bay - until respiration was maximally blocked. basal (routine) respiration was set at % to which all other data points were related. cell viability, cell death, metabolic assays, and flow cytometry melanoma cells were seeded in well plates in triplicates at a density of – cells/well and incubated in culture medium. the next day, the culture medium was exchanged to assay medium as described above and cells were treated with various concentrations of bay- or dmso added to media using a dispenser (hp d digital dispenser). after h, cell viability was measured using celltiter-fluor (ctf, promega) according to the manufac- turer’s protocol. fluorescence was detected (excitation nm, emission nm) in a microplate reader (tecan) after min of incubation at °c. ic values were calcu- lated from triplicate experiments using graphpad prism software, using curves from plots of fluorescence intensity vs. bay - in each cell line. for the analysis of time- dependent effects of bay - , cell viability was assessed by crystal violet assay. briefly, cells were seeded in well plates, treated with bay - ( nm) or dmso as control and after incubation stained with crystal violet solution ( . % crystal violet, % ethanol, % for- maldehyde). then, plates were rinsed with water and crys- tal violet incorporated by the cells was re-solubilized in % sds solution. absorbance at nm was measured using a microplate spectrophotometer (benchmark plus, biorad). results are expressed as percentage of cell viability relative to untreated controls. for measurements of cell death, ml cells were seeded in six well plates at , cells/well. when adherent cells were fully attached, culture media was removed and replaced with assay media containing bay - ( nm), vitamin e ( μm), or dmso as a control. cell death was measured after h using propidium iodine and flow cytometry. extracellular lactate was measured in assay medium of treated cells using cobas c analyzer (roche). results were normalized to cell number. atp measurements were conducted using ctg (promega) according to the manufacturer’s protocol. schöckel et al. cancer & metabolism ( ) : page of for mitotracker stainings, cells were seeded into well imaging plates (cell carrier, perkin elmer) at cells/well in μl and incubated over night at °c and % co . then, cells were treated with vemurafe- nib ( μm) or dmso as control for h. mitotracker green fm (invitrogen) staining was carried out using manufacturer’s recommended protocols. the dna dye hoechst was added to the mitotracker staining solution (in dmem culture medium) to achieve a final concentra- tion of μg/ml hoechst and nm mitotracker green fm. cells were then incubated for min at °c and % co . afterwards, staining solution was removed and μl/well pre-warmed medium was added. the cells were then imaged with the opera® spinning disk automated microscope (perkin elmer), imaging six wells per condi- tion with sites/well using a × objective utilizing separate nm and nm laser excitation. imaging data was subsequently analyzed using the metaxpress software (version , molecular devices). nuclei segmentation and mitochondrial staining quantification was performed on using built in detection routines. as measurement for mitochondrial mass, total mitochondria staining intensity per well was divided by the total count of nuclei per well. data are represented as the mean ± sd normalized to rela- tive cell number. ros measurements to measure intracellular ros levels, μm cell permeable dichlorofluorescein diacetate (cm-h dcfda) (invitrogen) or μm cell permeable mitosox (life technologies) were used as fluorescent dyes. the non-fluorescent redox- reactive dye cm-h dcfda can get oxidized by intracellu- lar ros yielding the fluorescent probe cm-h dcf, which is proportional to cytosolic ros. mitosox describes the non-fluorescent dye hydroethidium which gets oxidized by superoxide radicals yielding the fluorescent ethidium product. an equal number of cells were seeded in six well plates, treated with various concentrations of bay - or bay - ( nm) in combination with vita- min e ( μm) or nac ( mm) as indicated or h. cells were incubated with phenol-red-free assay medium con- taining either cm-h dcfda or mitosox dye in for min at °c. cells were then washed with pbs, trypsi- nized, resuspended in pbs, and immediately analyzed by flow cytometry. biochemicals bay - was developed by bayer pharma ag [ ]. vemurafenib was obtained from apac pharma (charge clev - - apac lot apwj plx). n-acetyl- cysteine (nac) and vitamin e (α-tocopherol) were obtained from sigma. statistics graphpad software was used for statistical analysis. statis- tical analyses for the comparison of more than two groups were performed by one-way anova, followed by a sidak’s multiple comparison test (pairwise comparisons). a two-tailed t test was performed to compare between two groups (two-group comparisons). p < . was consid- ered to indicate a statistically significant difference. results inhibition of mitochondrial complex i with bay - in melanoma cells induces cell death in vitro and reduces tumor growth in vivo bay - has been shown to be a highly potent and selective inhibitor of mitochondrial complex i [ ]. we demonstrate that bay - -mediated complex i in- hibition induced significant reduction of cell viability in a dose-dependent manner in several brafv e (g- , sk-mel- , sk-mel- , and a- ) and also braf wild type (sk-mel- , ipc- , chl- , and colo- ) melan- oma cell lines. bay - showed highly potent activ- ity with an estimated ic in the one-digit nanomolar range after days of treatment (fig. a). using the same treatment protocol, bay - induced – % of cell death and reduced viability in a time-dependent manner (fig. b, c). to address whether bay - -mediated complex i inhibition is efficient at reducing melanoma tumor growth in vivo, we tested the inhibitor in four braf mutant melanoma xenograft models using g- , sk-mel- , a- , and lox-imvi cancer cells. upon sub- cutaneous melanoma cell injection, tumors were allowed to grow to around mm before the mice were treated with vehicle or mg/kg bay - (once a day) by oral gavage (p.o.). bay - induced a significant reduction in tumor size in all braf mutant melanoma xenografts, as well as a reduction in tumor weight without affecting body weight of the mice (fig. d and additional file : figure s a, b, c). interestingly, bay - has stronger activity in the slow-growing melan- oma xenografts (g- and sk-mel- ). also, bay - displayed a strong reduction in tumor growth in two patient-derived braf melanoma models (mexf and mexf ) (fig. e). inhibition of mitochondrial complex i with bay - blocks oxphos and triggers glycolysis in melanoma cells to investigate the mechanism by which bay - - mediated mitochondrial complex i inhibition induced cell death and anti-tumor activity in melanoma cells, we first determined the direct effect of the inhibitor on mitochon- drial oxygen consumption. addition of bay - induced a dose-dependent reduction of basal ocr in a- and sk-mel- cells (fig. a). using polarographic schöckel et al. cancer & metabolism ( ) : page of oxygen sensors a strong reduction in ocr was also already observed in the low nanomolar range matching the ic viability results (fig. a and additional file : figure s a). this indicates selective inhibition of mito- chondrial complex i and rationalizes the use of minimal concentrations of bay - that maximally inhibit cell growth (fig. a) and mitochondrial respiration (additional file : figure s a) in all further experiments. in the same cells, the ecar of the cell culture media, an indirect readout of glycolysis, increased (fig. b) a c e b d bay - [ nm] time [hours] v ia b le c e ll s ( % o f c tr l) g- sk-mel- sk-mel- a- g- time after inoculation [days] t u m o r v o lu m e m e a n [ m m + /- s d ] * * * * * sk-mel- t u m o r v o lu m e m e a n [ m m + /- s d ] bay - [ mg/kg] p.o. vehicle * * * * * * mexf * * * mexf * * * % d e a d c e ll s ( p ip o s it iv e ) g- a- sk-mel- dmso bay - [ nm] h * * * g- sk-mel- sk-mel- a- g- sk-mel- sk-mel- a- ic [nm] bay - log conc ( m) v ia b le c e ll s ( % o f c tr l) c t f - - - - sk-mel- chl- colo- ipc- braf wt melanoma ( h treatment) sk-mel- chl- colo- ipc- ic [nm] - - - - v ia b le c e ll s ( % o f c tr l) c t f braf v e melanoma ( h treatment) bay - log conc ( m) bay - [ mg/kg] p.o. vehicle t u m o r v o lu m e m e a n [ m m + /- s d ] t u m o r v o lu m e m e a n [ m m + /- s d ] bay - [ mg/kg] p.o. vehicle bay - [ mg/kg] p.o. vehicle time after inoculation [days] time after inoculation [days]time after inoculation [days] fig. inhibition of mitochondrial complex i with bay - in melanoma cells induces cell death in vitro and reduces tumor growth in vivo. a braf wild type and mutant melanoma cells were treated with various concentrations of bay - . cell viability was measured after h. ic values were calculated using graphpad prism (n = ). b melanoma cells were treated with bay - ( nm). cell death was measured after h using propidium iodine (n = ). c melanoma cells were treated with bay - ( nm). cell viability was measured after , , and h (n = ). d nude mice were xenotransplanted with either × sk-mel- ( % matrigel) or × g- ( % matrigel) human melanoma cells (n = per group). when tumor area reached around mm , mice were treated once a day with vehicle or mg/kg bay - per oral gavage (p.o.). e nude mice bearing patient-derived (mexf , mexf , n = per group) melanoma xenograft tumors were treated orally (p.o.), once a day with vehicle or mg/kg bay - . data are represented as the mean ± sd. *p < . schöckel et al. cancer & metabolism ( ) : page of which was also accompanied with a significant rise in extracellular lactate of bay - -treated cells (fig. c). this data indicates that bay - in- duced a gradual switch from oxphos to glycolysis demonstrated by the immediate drop in ocr and the time-dependent increase in the glycolytic product lactate (additional file : figure s b). detailed investigation of mitochondrial function showed that, in addition to de- creasing basal ocr, bay - also resulted in dimin- ished maximal respiratory capacity of the mitochondria, which was seen upon the addition of the mitochondrial uncoupler fccp (fig. d and additional file : figure ed n o rm a li ze d o c r ( p m o l/m in ) o ra n g e /g re e n r a ti o ( a u ) (m it o c h o n d ri a l m e m b ra n e p o te n ti a l) n o rm a li ze d o c r ( p m o l/ m in ) o ra n g e /g re e n r a ti o ( a u ) (m it o c h o n d ri a l m e m b ra n e p o te n ti a l) time (min) . . . . a- sk-mel- g- dmso nm nm nm nm µm dmso bay - [ nm] h cccp [ µm] min bay - [ nm] h g- bay - fccp aa + rotenoneoligomycin fig. inhibition of mitochondrial complex i with bay - blocks oxphos and triggers glycolysis in melanoma cells. a ocr was measured using seahorse analyzer in braf mutant melanoma cells. bay - was injected (black arrow) in different concentrations (n = ). b ecar was measured using seahorse analyzer in braf mutant melanoma cells. bay - was injected (black arrow) in different concentrations (n = ). c melanoma cells were treated with bay - ( nm). extracellular lactate was measured in cell culture supernatant after h (n = ). d ocr was measured using seahorse analyzer in g- cells. bay - was injected (black arrow) in different concentrations followed by consecutive injections of oligomycin ( μm), fccp ( . μm), and antimycin a ( μm)/rotenone ( μm) (n = ). e melanoma cells were treated with different concentrations of bay - . after h, mitochondrial membrane potential was measured using mito-id assay (n = ). cccp ( μm) was used as positive control. data are represented as the mean ± sd. *p < . schöckel et al. cancer & metabolism ( ) : page of s c). furthermore, bay - treatment induced a partial mitochondrial membrane depolarization in melan- oma cells which can potentially lead to an energy crisis due to the lack in atp production (fig. e). complex i inhibition using bay - reduces atp levels and induces an energy crisis in melanoma cells to further address the mechanism behind the bay - -induced anti-tumorigenic phenotype, cellular atp levels were measured. this also allowed us to investigate the role of the observed changes in mitochondrial respir- ation and membrane polarization. we show that bay - caused a drastic, dose-dependent decrease of total cellular atp levels in melanoma cell lines, h after inhibitor treatment (fig. a). in order to determine if this drop in atp had an effect on metabolic signaling, we looked at the activity of ampk upon bay - treatment, a critical energy sensor that is activated by low atp levels. it has been shown that ampk is acti- vated in the liver in response to therapeutic doses of metformin and phenformin due to mitochondrial com- plex i inhibition [ ]. here, we found that bay - significantly induced phosphorylation and activation of ampk in melanoma cells (fig. b) which is consistent with the drop in atp levels (fig. a). bay - also activated raptor, a well-defined downstream target of ampk (fig. c). these results suggest that bay - induces an energy crisis in melanoma cell lines, which causes ampk and raptor activation. interestingly, bay - -mediated complex i inhibition also re- duced the activation of extracellular-signal-regulated kinase / (erk / ) (fig. d). keeping in mind that bay - appeared to stimulate glycolysis (fig. and additional file : figure s ) potentially leading to the de- pletion of extracellular glucose, we next cultured the mel- anoma cells in a medium with high glucose ( mm). under these conditions cell viability was rescued (fig. e), ampk was not activated (fig. f) and cellular atp con- tent was not reduced in bay - -treated melanoma cells (fig. g). taken together, these results suggest that melanoma cells require glucose-driven glycolysis for atp production to survive in the presence of bay - . bay - -mediated complex i inhibition increases mitochondrial and cytosolic ros levels resulting in ros-mediated cell death next, we focused on already known outcomes of complex i inhibition and their potential role in causing the anti- tumorigenic phenotype upon bay - treatment. it is well established that mitochondrial complex i constitutes a major source of ros which can be toxic to the cell at high levels. studies have shown that the known complex i in- hibitor rotenone significantly induces the production of high levels of mitochondrial ros, leading to oxidative stress [ , ]. interestingly, here, we found that culturing bay - -treated melanoma cells in excess glucose media ( mm) did not only stabilize atp levels (fig. g) but also significantly decreased ros levels (fig. h). to further investigate the effect of bay - on ros levels, we used the redox-reactive dye cm-h dcfda and the mitochondrial targeted dye mitosox which measure the levels of cytosolic and mitochondrial ros, respectively. as expected, bay - generated high levels of mito- chondrial ros, in a dose-dependent manner, as well as cytosolic ros over time in melanoma cells (fig. a, b and additional file : figure s a). in order to evaluate the downstream effects of the bay - -induced increase in ros levels, we looked at the well-established ros marker nuclear factor (erythroid-derived )-like (nrf ), which is a transcrip- tion factor and master regulator of the antioxidant re- sponse. nrf is known to be stabilized upon ros in order for the cell to balance potentially cell-damaging oxidative stress [ – ]. bay - induced the stabilization of nrf in melanoma cells (fig. c), which was abrogated in the presence of high glucose (fig. d). to establish whether increased levels of ros are re- quired for bay - -mediated cell death, we treated melanoma cells with bay - in the presence of the antioxidants vitamin e and the reduced glutathione pre- cursor n-acetyl cysteine (nac). first, we show that the vitamin e and nac reversed ros levels upon bay - treatment in melanoma cells (fig. e, f and additional file : figure s b). furthermore, nrf levels were reversed by the addition of vitamin e in inhibitor- treated melanoma cells (fig. g). in addition to decreas- ing ros stress, the antioxidant treatment abrogated bay - -induced cell death, suggesting that ros might play a causal role in this process (fig. h and additional file : figure s c). our findings also trans- lated into cell death and redox-regulated protein expres- sion [ , ]. the expression of the cell death marker cleaved poly (adp-ribose) polymerase (parp) is induced by bay - and rescued in the presence of the anti- oxidant vitamin e and nac (fig. i and additional file : figure s d) and also by the addition of excess glucose (fig. j). furthermore, we looked at the mitogen- activated protein kinase (mapk) p , which is a well characterized ros sensor, described to induce ros- mediated cell death [ , ]. indeed bay - treat- ment induced the activation of p mapk which was reversed by vitamin e treatment in melanoma cells (fig. k). interestingly, bay - -induced ampk activation was also rescued by the antioxidant (fig. l). taken together, our data suggest that melanoma cells rely on glycolysis and the resulting atp production, as well as on redox balance to survive in the presence of bay - . we show that bay - -mediated cell schöckel et al. cancer & metabolism ( ) : page of e f g h a b d c p h o s p h o -a m p k e x p re s s io n l e v e l (n o rm a li s e d t o t o ta l a m p k a n d a c ti n ) a- g- dmso bay - [ nm] h * * a- ( h treatment) c y to s o li c r o s l e v e ls c m -h d c f d a m f i (a u ) mm glucose mm glucose control bay - [ nm] * * * c e ll u la r a t p l e v e l (n o rm a li ze d t o c o n tr o l) dmso bay - [ nm] bay - [ nm] oligomycin [ m] a- sk-mel- g- * * * * * c e ll u la r a t p l e v e l (n o rm a li ze d t o c o n tr o l) dmso bay - [ nm] bay - [ nm] a- sk-mel- mm glucose mm glucose mm glucose mm glucose * * sk-mel- - - - - mm glucose mm glucose mm glucose > mm glucose ic [nm] a- bay - log conc ( m) v ia b le c e ll s ( % o f c tr l) c t f - - - - mm glucose mm glucose ic [nm] mm glucose > mm glucose sk-mel- - - - - mm glucose mm glucose mm glucose > mm glucose ic [nm] g- - - - - mm glucose mm glucose mm glucose > mm glucose ic [nm] bay - log conc ( m) bay - log conc ( m) bay - log conc ( m) v ia b le c e ll s ( % o f c tr l) c t f v ia b le c e ll s ( % o f c tr l) c t f v ia b le c e ll s ( % o f c tr l) c t f fig. (see legend on next page.) schöckel et al. cancer & metabolism ( ) : page of death is caused by atp depletion and ros stress, which can both be alleviated by the addition of excess glucose. vemurafenib increases mitochondrial density and respiration in braf mutant melanoma cells our data show that bay - has substantial effects as a single agent against melanoma in vitro and in vivo, in- cluding braf mutant melanoma. having established that bay - treatment leads to a metabolic switch away from oxphos making melanoma cells dependent on gly- colysis, we next wanted to test whether the efficacy of bay - could be enhanced by a therapeutic agent, based on its mechanism of action. recent studies have highlighted that mutant braf inhibition makes melan- oma cells dependent on oxphos and mitochondrial atp production [ ]. in fact, the selective mutant brafv e inhibitor vemurafenib actively reduced glucose uptake in braf mutant melanoma cell lines [ ]. in brafv e melanomas, this switch to oxphos is seen in conjunction with the development of drug resistance against selective inhibitors which commonly occurs and represents a major limitation to clinical efficacy [ , ]. since the mitochondrial complex i inhibitor bay - impairs oxphos and causes the cells to use glycoly- sis, it impinges on the dependency on mitochondrial metabolism, which is forced by braf inhibitors like vemurafenib. this opposing metabolic dependency sug- gests a rationale for combining vemurafenib with bay - in order to exploit the mitochondrial pathway that vemurafenib-treated melanoma cells need in order to sur- vive. combination treatment could potentially increase energy stress by taking away the respective adaptive meta- bolic upregulation leading to augmented melanoma cell death compared to single agent treatment. to validate the vemurafenib literature data with regard to proliferation, oxphos, mitochondrial function, and biogenesis, braf mutant melanoma cells were treated with vemurafenib for h. we show that vemurafenib im- paired melanoma cell proliferation (fig. a) and increased mitochondrial density (fig. b). the mitochondrial density of braf wild type cells, mewo, was not affected by vemurafenib (fig. b). furthermore, vemurafenib led to a significant increase in basal and atp-coupled oxygen con- sumption rate which was not observed in braf wild type cells (fig. c, d). our data suggests that vemurafenib induces oxphos in braf mutant melanoma cells, mak- ing it a good combination drug for bay - . inhibition of complex i using bay - in combination with vemurafenib attenuated braf mutant melanoma tumor growth in vivo in order to test the in vivo efficacy of bay - and vemurafenib as single agents and in combination, we used the inhibitors in a braf mutant melanoma cell xenograft model. upon subcutaneous injection of sk-mel- mel- anoma cell, tumors were allowed to grow to around mm before the mice were treated with either vehicle, mg/kg bay - , mg/kg vemurafenib, or a com- bination of both inhibitors by oral gavage. we show that mice treated with the combination of bay - and vemurafenib have enhanced reduction in melanoma tumor growth compared to the reduction seen in mice treated with each agent alone (fig. a, b). furthermore, combin- ation treatment augmented the effect on reduction in tumor weight compared to single agent treatment without affecting body weight of the mice (fig. c, d). our data in- dicate that bay - -mediated complex i inhibition, in addition to its function as a single agent, may have thera- peutic benefits in combination treatment with the mutant braf inhibitor vemurafenib in melanoma. discussion selective inhibition of mitochondrial complex i with bay - in melanoma cells induces cell death in vitro and reduces tumor growth in vivo in recent years, mitochondrial metabolism has emerged as a target for cancer therapy due to the appreciation of mito- chondria as a central metabolic organelle required for tumorigenesis [ , , ]. however, there is still a lack of selective cancer therapies targeting oxphos and mito- chondrial metabolism. in this study, we used the mito- chondrial complex i small molecule inhibitor bay - and investigated its effects in melanoma cells. in addition to causing proliferation impairment and cell death in a (see figure on previous page.) fig. complex i inhibition using bay - reduces atp levels and induces an energy crisis in melanoma cells. a melanoma cells were treated with different concentrations of bay - and atp was measured after h. oligomycin ( μm) served as positive control (n = ). b, c melanoma cells were treated with bay - ( nm). cell lysates were collected from treated cells ( h) and probed with antibodies recognizing phospho-ampk (thr ), total ampk, c phospho-raptor (ser ), d anti-phospho-erk / (thr /tyr ), and anti-erk / . actin was used as a loading control. e melanoma cells were treated with various concentrations of bay - . cell viability was measured in high ( mm) and low ( mm) glucose medium after h (n = ). ic values were calculated using graphpad prism. f a- cells were treated with bay - ( nm) under low- ( mm) and high ( mm) glucose conditions. cell lysates were collected from treated cells ( h) and probed with antibodies recognizing phospho-ampk (thr ) and total ampk. actin was used as a loading control. g melanoma cells were treated with bay - ( nm) under low- ( mm) and high ( mm) glucose conditions and atp was measured after h (n = ). h a- cells were treated with bay - ( nm) under low- ( mm) and high ( mm) glucose conditions. cytosolic ros levels were measured using the ros-reactive dye cm-h dcfda after h (n = ). data are represented as the mean ± sd. *p < . schöckel et al. cancer & metabolism ( ) : page of a b c d gfe h mitosox ( h treatm ent) g- a- sk-mel control bay - [ nm] bay - [ nm] + vite [ µm] cytosolic ros levels ( h treatm ent) c y to s o li c r o s l e v e ls c m -h d c f d a m f i ( a u ) g- a- sk-mel- control bay - [ nm] + vite [ µm] bay - [ nm] % d e a d c e ll s ( p i p o s it iv e ) % d e a d c e ll s ( p i p o s it iv e ) % d e a d c e ll s ( p i p o s it iv e ) % d e a d c e ll s ( p i p o s it iv e ) i j k l c y to s o li c r o s l e v e ls h h m it o c h o n d ri a l r o s l e v e ls m it o s o x m f i (a u ) h h c m -h d c f d a m f i (a u ) bay - [ nm]bay - [ nm] m it o c h o n d ri a l r o s l e v e ls m it o s o x m f i (a u ) a- sk-mel- g- sk-mel- ( h treatment) ( h treatment) ( h treatment) ( h treatment) dmso bay [ nm] bay [ nm] + vite [ µm] dmso bay [ nm] bay [ nm] + vite [ µm] dmso bay [ nm] bay [ nm] + vite [ µm] dmso bay [ nm] bay [ nm] + vite [ µm] fig. (see legend on next page.) schöckel et al. cancer & metabolism ( ) : page of a b c d vemurafenib ( h treatment) logconc ( m) v ia b le c e ll s ( % o f c tr l) - - a- sk-mel- g- sk-mel- g- . sk-mel- . sk-mel- . a- . ic [µm] fig. vemurafenib increases mitochondrial density and respiration in braf mutant melanoma cells. a braf mutant melanoma cells were treated with various concentrations of vemurafenib. cell proliferation was measured after h. ic values were calculated using graphpad prism (n = ). b mitotracker green fluorescence (left) and quantification (right) (average intensity per cell) of braf mutant and braf wild type melanoma cells treated with vemurafenib ( μm) for h (n = ). c ocr was measured using seahorse analyzer in braf mutant and braf wild type melanoma cells after treatment with vemurafenib ( μm) for h (n = ). d atp-coupled ocr (after injection of oligomycin ( μm)) was analyzed using seahorse in braf mutant melanoma cells after treatment with vemurafenib ( μm) for h (n = ). data are represented as the mean ± sd. *p < . (see figure on previous page.) fig. bay - -mediated complex i inhibition increases mitochondrial and cytosolic ros levels resulting in ros-mediated cell death. a g- cells were treated with bay - ( nm). mitochondrial ros levels were measured using the mitosox dye after and h (n = ). b g- cells were treated with bay - ( nm). cytosolic ros levels were measured using the ros-reactive dye cm-h dcfda after and h (n = ). c–d melanoma cells were treated with bay - ( nm) under (c and d) low- ( mm) and d high ( mm) glucose conditions. cell lysates were collected from treated melanoma cell lines ( h) and probed with antibodies recognizing nrf . actin was used as a loading control. e–f melanoma cells were treated for h with bay - ( nm) alone or in combination with the antioxidant vitamin e ( μm). e mitochondrial and f cytosolic ros levels were analyzed using flow cytometry (n = ). g sk-mel- cells were treated with bay - ( nm) alone or in combination with vitamin e ( μm). cell lysates collected from treated sk-mel- cells ( h) were probed with antibodies recognizing nrf . actin was used as a loading control. h braf mutant melanoma cells were treated with bay - ( nm) alone or in combination with vitamin e ( μm). cell death was measured after h using propidium iodine (n = ). i–j melanoma cells were treated with bay - ( nm) alone or in combination with vitamin e ( μm) under (i and j) low- and j high glucose conditions. cell lysates collected from treated a- and g- cells ( h) were probed with antibodies recognizing cleaved parp. actin was used as a loading control. k–l braf mutant melanoma cells were treated with bay - ( nm) alone or in combination with vitamin e ( μm). cell lysates collected from treated cells ( and h) were probed with antibodies recognizing k phospho-p mapk and total p mapk and l phospho-ampk (thr ) and total ampk. actin was used as a loading control. data are represented as the mean ± sd. *p < . schöckel et al. cancer & metabolism ( ) : page of variety of braf mutant and wild type melanoma cells, bay - also revealed strong anti-tumor activity as a single agent in vivo. interestingly, bay - reduced tumor growth most effectively in slowly proliferating tu- mors (e.g., the sk-mel- xenograft model) when com- pared to rapidly proliferating tumors (e.g., the a- xenograft model) (fig. d and additional file : figure s ). this observation might be explained by the fact that fast proliferating tumors are more glycolytic therefore consume more glucose than slow-growing tumors [ – ]. hence, these latter tumors are more oxphos-dependent and therefore more sensitive to bay - -induced complex i inhibition. based on our in vivo data, it is tempting to speculate that tumor growth rate might be used as a bio- marker readout of sensitivity to complex i inhibition. in line with our observation that glycolytic tumors are more resistant to complex i inhibition in vivo we suggest that bay - might be more effective in conditions of limiting glucose availability (e.g., in the center of a tumor). indeed, bay - did not affect melanoma cell viability when mm of extracellular glucose was present in the cell culture media, whereas at mm glucose, the inhibitor induced atp depletion and melanoma cell death (fig. ). this suggests that fig. inhibition of complex i using bay - in combination with vemurafenib attenuated melanoma tumor growth in vivo. a nude mice were xenotransplanted with × sk-mel- ( % matrigel) human melanoma cells (n = per group). mice were treated orally (p.o.) with vemurafenib ( mg/kg, twice a day) or for combination studies with vemurafenib ( mg/kg, twice a day) and bay - ( mg/kg, once a day). tumor volume was measured. b relative tumor size (%) of individual sk-mel- xenograft tumors (tumor area at study end × / tumor area at study begin). partial regression, < % (tumor size at study end > % smaller than original tumor size at study start); stable disease, – % (tumor size between % smaller and % bigger of original size); progressive disease, > % (tumor size at study end > % bigger than original size). c tumor weights of individual sk-mel- xenograft tumors. d body weights of mice (n = ) bearing human sk-mel- xenografts treated orally (p.o.) once daily with vehicle (ethanol/solutol/water = : : ), or with vemurafenib ( mg/kg, twice a day), or for combination studies with vemurafenib ( mg/kg, twice a day) and bay - ( mg/kg, once a day). data are represented as the mean ± sd. *p < . schöckel et al. cancer & metabolism ( ) : page of bay - targets oxphos in melanoma cells and that the effects thereof depend on the amount of extra- cellular glucose (additional file : figure s ). several retrospective studies suggested that metformin, commonly used in patients with type ii diabetes, inhibits complex i and shows anti-tumor effects [ – ]. in con- trast to metformin, bay - showed strong anti- proliferative effects at low nanomolar concentrations and anti-tumor effects at lower doses. furthermore, the efficacy of metformin may be further limited by the expression of organic cation transporters (octs) required for uptake and subsequent inhibition of oxphos [ ]. bay - induces cell death via an oxidative stress mechanism compared to normal cells, cancer cells are characterized by an increased rate of ros production. to prevent oxida- tive stress induction, cancer cells upregulate ros- detoxifying systems [ , , ], thereby, keeping the ros level within its pro-tumorigenic range [ , ]. here, we observed that bay - reduced cellular atp levels (fig. a) and increased cellular ros levels (fig. a, b). this increase was associated with higher levels of nrf and phosphorylated p mapk. interestingly, bay - partially prevented ros stimulation in mm glucose medium and in the presence of antioxidants (vitamin e and nac) (figs. h, e, f and additional file : figure s b). also, under these conditions, bay - -induced cell death was prevented (fig. h and additional file : figure s c). this suggests that bay - inhibits complex i and thereby stimulates ros generation and induction of oxidative stress to induce cell death. alter- natively, a (parallel) mechanism might be active in which complex i inhibition renders the cells completely dependent on glycolysis for atp generation. when extracellular glucose levels are limited (i.e., mm), this glycolytic switch is unable to prevent atp depletion and the ensuing cell death. hence, bay - inhibits tumorigenesis through multiple mechanisms including the induction of cancer cell death in condi- tions where glucose concentration is limited (leading to atp depletion) and via induction of oxidative stress and a ros-mediated cell death (additional file : figure s ). although it remains to be determined how high extracellular glucose levels lower ros levels, a similar phenomenon has been observed in cells with inherited and inhibitor-induced complex i deficiency [ ]. the combination of vemurafenib and bay - aug- ments anti-tumor effects in braf mutant melanoma upon treatment with the mutant brafv e inhibitor vemurafenib, melanoma cells upregulate mitochondrial oxygen consumption and decrease glycolysis [ ]. this suggests that these cells switch their cellular atp produc- tion from glycolysis towards mitochondrial metabolism, making their survival more dependent on mitochondrial function. in contrast, chronic inhibition of complex i was demonstrated to induce a fully glycolytic phenotype in pri- mary human skin fibroblasts [ ]. since the latter is very similar to the effects induced by bay - in this study, we treated melanoma cells with a combination of vemurafenib and bay - . under these conditions, we expected that the vemurafenib-induced stimulation of mitochondrial metabolism is counterbalanced by the in- hibition of mitochondrial function using bay - . interestingly, when compared to their use as single agents, the combination of bay - and vemurafenib in- duced augmented tumor regression in nude mice bearing braf mutant melanoma xenografts (fig. ). in agreement with our approach, additive effects between biguanides and braf inhibitor vemurafenib have been demonstrated previously [ , ]. one explanation for the augmented anti-tumor effect might involve the activating effect of bay - on ampk. it has been demonstrated that mutated brafv e suppresses the activity of ampk by promoting inhibitory phosphorylation of its upstream kinase (lkb ) by erk / and that this ampk inhibition is critical for melanoma cell proliferation and anchorage-independent growth [ ]. interestingly, we show that bay - suppresses the phosphorylation of erk / possibly allowing ampk acti- vation. our results suggest that bay - induces an energy crisis in braf mutant melanoma cell lines ac- companied by the downregulation of the raf-mek- erk signaling cascade, thereby, potentially allowing activation of ampk and raptor (fig. a, b, c, d, and additional file : figure s ). another possible explanation for the augmented anti- tumor effect of vemurafenib and bay - might be the heterogeneous nature of tumors with respect to oxygen availability. relative to normal tissue, tumors display a much steeper oxygen gradient with its level dropping close to zero in necrotic core areas. adapta- tion to these hypoxic conditions is for instance medi- ated through the stabilization of the transcription factor hif- , which controls the expression of many genes involved in glycolysis [ ]. in this context, it was dem- onstrated that bay - treatment suppressed hif- α protein levels and the expression of hif- target genes in a h xenograft model [ ]. this means that bay - might be more effective when combined with other treatments that lower the availability of oxy- gen and extracellular glucose in cancer cells. interest- ingly, vemurafenib has been shown to suppress glucose uptake in melanoma cells [ ] and also in tumors from patients with brafv e melanoma [ ]. therefore, it can be hypothesized that a therapeutic advantage is schöckel et al. cancer & metabolism ( ) : page of achieved in braf mutant melanoma tumors by first blocking oxphos and adaptation to hypoxia with bay - , followed by subsequent downregulating of glycolysis using vemurafenib. conclusions compared to standard chemotherapy, vemurafenib ex- tends melanoma survival up to months [ , ]. in spite of dramatic initial tumor shrinkage in patients with brafv e melanoma, long-term efficacy is thwarted due to emergence of drug resistance and drastic tumor re- growth [ ]. here, we confirm previous findings that melanoma cells adapt to braf inhibitors by upregu- lating oxphos therefore validating our approach to effectively target this pathway with the selective mito- chondrial complex i inhibitor bay - . our study holds promise for the design of future combin- ation therapies by broadening the understanding of how to prevent the development of resistance to oncogene-targeted therapies which may increase their initial therapeutic efficacy. based on our findings, we suggest combining vemurafenib with complex i inhib- itors in braf mutant melanoma in order to diminish the ability of cancer cells to adapt to either agent. additional files additional file : figure s . bay - reduces tumor growth in melanoma cells in vivo. (a) scid mice bearing established a- ( . x cells/ mouse in % matrigel, n = per group) and lox-imvi ( . × cells/ mouse in % matrigel, n = per group) human xenograft tumors were treated orally (p.o.), once daily with vehicle (ethanol/solutol/water = : : ) or bay - ( mg/kg). (b) tumor weights of human melanoma xenografts (a- , g- , sk-mel- , lox-imvi) treated orally (p.o.), once daily with vehicle (ethanol/solutol/water = : : ) or bay - ( mg/kg). (c) body weights of mice bearing patient-derived (mexf , mexf ) and human melanoma xenografts (g- and sk-mel- ) treated orally (p.o.), once daily with vehicle (ethanol/solutol/water = : : ) or bay - ( mg/kg). data are represented as the mean ± sd. *p < . . additional file : figure s . inhibition of mitochondrial complex i with bay - inhibits oxphos and triggers glycolysis in melanoma cells. (a) ocr was measured using polarographic oxygen sensors in a two-chamber oxygraph (oroboros) in melanoma cells. bay - was injected in different concentrations (n = ). (b) sk-mel- and g- cells were treated with bay - ( nm) and the time-dependent production of extracellular lactate was measured (n = ). (c) ocr was measured using seahorse analyzer in g- cells. bay - was injected (black arrow) in different concentrations followed by consecutive injections of oligomycin ( μm), fccp ( . μm) and antimycin a ( μm)/rotenone ( μm) (n = ). data are represented as the mean ± sd. *p < . . additional file : figure s . complex i inhibition causes oxidative stress and ros-mediated cell death. (a) g- and sk-mel- cells were treated with increasing concentrations of bay - . mitochondrial ros levels were measured using the mitosox dye after hours (n = ). (b) a- cells were treated with bay - ( nm) and the antioxidant, nac ( mm). cytosolic ros levels were measured using the redox-reactive dye cm-h dcfda after h (n = ). (c) melanoma cells were treated with bay - ( nm) and the antioxidant nac ( mm). cell death was measured after h using propidium iodine (n = ). (d) g- cells were treated with bay - ( nm, nm) and the antioxidant, nac ( mm). cell lysates were collected from treated g- cells ( h) and probed with antibodies recognizing cleaved parp. actin was used as a loading control. data are represented as the mean ± sd. *p < . . additional file : figure s . melanoma cells are sensitive to bay - -mediated complex i inhibition by undergoing an energy crisis and ros-mediated cell death. under limiting glucose conditions ( mm), the mitochondrial complex i inhibitor bay - induces a metabolic switch from oxphos to glycolysis in melanoma cells. results of bay - - mediated complex i inhibition include a reduction in the total cellular atp pool and therefore ampk activation, suppression of erk / phosphorylation, and the induction of oxidative stress. ros stress is marked by stabilization of nrf , phosphorylation of p mapk, and ampk as well as cell death signaling marked by cleaved parp. abbreviations ampk: amp-activated protein kinase; ecar: extracellular acidification rate; ocr: oxygen consumption rate; oxphos: oxidative phosphorylation; ros: reactive oxygen species. competing interests laura schöckel, andrea glasauer, katharina bitschar, gerrit erdmann, carolyn algire, andrea hägebarth, charlotte kopitz, and mélanie héroult are full-time employees of bayer pharma ag. farhan basit, hoa truong, peter h.g.m. willems, and werner j.h. koopman have no competing interests. authors’ contributions ls, ag and fb planned the experiments. ls carried out the in vivo experiments, seahorse bioanalyzer experiments, ros measurements, cell culture experiments and drafted the manuscript. ag helped interpret results and to draft the manuscript. fb carried out the oxygraph measurements and time-dependent viability assays. ls and ge carried out the mitotracker stainings and ge analyzed the data. fb, ht, phgmw, wjhk helped interpret results, provided feedback on the project and helped write the manuscript. ca, ah, cck and mh helped interpret results and provided feedback on the project. all authors read and approved the final manuscript. authors’ information not applicable. acknowledgements we thank our dedicated technicians andrea born, anita griephan, mike hoepner, katrin jänsch, seren nesan, maria spelling, and andrea triller for their expert technical assistance (bayer pharma ag). we acknowledge jori wagenaars (biochemistry, rimls, rumc) for assistance with the oxygraph measurements. we acknowledge bjoern riefke (bayer pharma ag) for providing help in the lactate measurements. author details bph, gdd, global therapeutic research group oncology ii, bayer pharma ag, müllerstraße , berlin, germany. department of biochemistry, radboud institute for molecular life science (rimls), radboud university medical centre (rumc), nijmegen, the netherlands. bayer ag innovation strategy, kaiser wilhelm allee , leverkusen, germany. received: july accepted: september references . cantor jr, sabatini dm. cancer cell metabolism: one 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/nejmoa . . flaherty kt, puzanov i, kim kb, ribas a, mcarthur ga, sosman ja, et al. inhibition of mutated, activated braf in metastatic melanoma. n engl j med. ; ( ): – . doi: . /nejmoa . submit your next manuscript to biomed central and take full advantage of: • convenient online submission • thorough peer review • no space constraints or color figure charges • immediate publication on acceptance • inclusion in pubmed, cas, scopus and google scholar • research which is freely available for redistribution submit your manuscript at www.biomedcentral.com/submit schöckel et al. cancer & metabolism ( ) : page of http://dx.doi.org/ . /j.ccr. . . http://dx.doi.org/ . /pnas. http://dx.doi.org/ . /j.molcel. . . http://dx.doi.org/ . /onc. . http://dx.doi.org/ . /jco. . . http://dx.doi.org/ . /nejmoa http://dx.doi.org/ . /nejmoa http://dx.doi.org/ . /nejmoa 	abstract 	background 	results 	conclusions 	background 	methods 	animal studies and cell cultures 	western blot analysis 	analysis of bioenergetics using the seahorse xf extracellular flux analyzer 	high-resolution respirometry 	cell viability, cell death, metabolic assays, and flow cytometry 	ros measurements 	biochemicals 	statistics 	results 	inhibition of mitochondrial complex i with bay - in melanoma cells induces cell death in vitro and reduces tumor growth in vivo 	inhibition of mitochondrial complex i with bay - blocks oxphos and triggers glycolysis in melanoma cells 	complex i inhibition using bay - reduces atp levels and induces an energy crisis in melanoma cells 	bay - -mediated complex i inhibition increases mitochondrial and cytosolic ros levels resulting in �ros-mediated cell death 	vemurafenib increases mitochondrial density and respiration in braf mutant melanoma cells 	inhibition of complex i using bay - in combination with vemurafenib attenuated braf mutant melanoma tumor growth in vivo 	discussion 	selective inhibition of mitochondrial complex i with bay - in melanoma cells induces cell death in vitro and reduces tumor growth in vivo 	bay - induces cell death via an oxidative stress mechanism 	the combination of vemurafenib and bay - augments anti-tumor effects in braf mutant melanoma 	conclusions 	additional files 	abbreviations 	competing interests 	authors’ contributions 	authors’ information 	acknowledgements 	author details 	references editorial electrification and renewable energy generation linni jian, hua bai, wenxiang zhao, and jianing liang department of electrical and electronic engineering, south university of science and technology of china, shenzhen , china department of electrical and computer engineering, kettering university, university avenue, flint, mi , usa school of electrical and information engineering, jiangsu university, no. , xuefu road, zhenjiang , china shenzhen institutes of advanced technology, chinese academy of sciences, xueyuan avenue, shenzhen university town, shenzhen , china correspondence should be addressed to linni jian; jian.ln@sustc.edu.cn received december ; accepted december copyright © linni jian et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. with increasing worldwide concerns on energy crisis and global warming, the topics on both electrification and renewable energy generation have become very attractive most recently. in our opinion, electrification means higher energy efficiency and thereby effective energy saving, while renewable energy generation means independence of fossil energy and thereby zero emission. consequently, electrifi- cation plus renewable energy generation points a promising way to environmental and sustainable development of human beings. nevertheless, we are still facing critical challenges in many aspects, such as how to harvest and utilize renewable energy in a high-efficient and low-costly way and how to process and convert electrical energy so as to better fulfill the demands in practical applications. the main objective of this special issue is to bring together researchers pursuing these fields and present their most recent working progress. after critical peer review, several papers are selected for publication in this issue, which cover many significant aspects related to the topic of electrification and renewable energy generation. l. xu et al. proposed a novel linear fault-tolerant permanent-magnet machine, which can be applied to high-efficient urban rail transit systems. y. fan et al. investigated a new flux-modulated brushless drive motor for electric vehicles. q. zhang et al. proposed a novel pulse-wide modulation method to reduce current ripples of z-source inverters. h. li et al. presented an effective multisource energy harvesting system for wireless sensor nodes. in order to solve problems arising from wide- area backup protection, z. zhang et al. proposed a novel protection algorithm. j. si et al. reported a tubular linear generator for harvesting wave energy. g. s. b. ganandran et al. reported the result of an investigation on the potential energy saving of the lighting systems at selected buildings of the universiti tenaga nasional. x. yu et al. built up a mathematic model to estimate hydraulic transients in long diversion type hydropower station. z. chen et al. proposed an optimal control method for maximizing the efficiency of direct drive ocean wave energy extraction system. y. xu et al. investigated the iron losses in deep-sea motors when taking into account the seawater compressive stress. n. dai et al. proposed a multifunctional voltage source inverter for renew- able energy integration and power quality conditioning. a. tomczewski presented the issues of a wind turbine flywheel energy storage system operation under real conditions. h. yuan et al. investigated biochars derived from banana at different thermotreatment temperatures and with or without chemical activation. a. hubackova et al. reported a solar drying technique for fish processing in cambodia. q. wang et al. proposed an optimal coefficients selection method for improving power quality of photovoltaic generation. m. a. islam et al. comprehensively reviewed various sources of renewable energy and their efficient utilization all over the world. c. peng and k. qian developed a zigbee-based building energy monitoring and control system. s. apelfröjd and s. eriksson presented a novel electrical system config- uration for variable speed wind turbines. h. geng and g. yang discussed the structure, performance, implementation cost, advantages, and disadvantages of different linear and hindawi publishing corporation e scientific world journal volume , article id , pages http://dx.doi.org/ . / / the scientific world journal nonlinear schemes applied to the pitch control of wind power generation systems. in summary, how to tap renewable energy sources effi- ciently and economically remains a huge challenge for all of us. with no doubt, development of technologies in electrical and electronic engineering, control engineering, and material sciences will bring our human being to a clean and sustainable future. we look forward to further new progress on the basis of and beyond the work reported in this issue. linni jian hua bai wenxiang zhao jianing liang tribology advances in hindawi publishing corporation http://www.hindawi.com volume international journal of aerospace engineering hindawi publishing corporation http://www.hindawi.com volume fuels journal of hindawi publishing corporation http://www.hindawi.com volume journal of petroleum engineering hindawi publishing corporation http://www.hindawi.com volume industrial engineering journal of hindawi publishing corporation http://www.hindawi.com volume power electronics hindawi publishing corporation http://www.hindawi.com volume advances in combustion journal of hindawi publishing corporation http://www.hindawi.com volume journal of hindawi publishing corporation http://www.hindawi.com volume renewable energy submit your manuscripts at http://www.hindawi.com hindawi publishing corporation http://www.hindawi.com volume structures journal of international journal of rotating machinery hindawi publishing corporation http://www.hindawi.com volume energy journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com journal of engineering volume hindawi publishing corporation http://www.hindawi.com volume international journal of photoenergy hindawi publishing corporation http://www.hindawi.com volume nuclear installations science and technology of hindawi publishing corporation http://www.hindawi.com volume solar energy journal of hindawi publishing corporation http://www.hindawi.com volume wind energy journal of hindawi publishing corporation http://www.hindawi.com volume nuclear energy international journal of hindawi publishing corporation http://www.hindawi.com volume high energy physics advances in the scientific world journal hindawi publishing corporation http://www.hindawi.com volume the role of the autophagy in myocardial ischemia/reperfusion injury biochimica et biophysica acta ( ) – contents lists available at sciencedirect biochimica et biophysica acta journal homepage: www.elsevier.com/locate/bbadis review the role of the autophagy in myocardial ischemia/reperfusion injury☆ sai ma a,b, yabin wang b, yundai chen a, feng cao a,b,⁎ a department of cardiology, chinese pla general hospital, # fuxing street, beijing , china b department of cardiology, xijing hospital, fourth military medical university, # changle west road, xi'an, shaanxi , china ☆ this article is part of a special issue entitled: autophag cardiometabolic diseases. ⁎ corresponding author at: department of cardiology # fuxing street, beijing , china. e-mail address: wind @gmail.com (f. cao). http://dx.doi.org/ . /j.bbadis. . . - /© elsevier b.v. all rights reserved. a b s t r a c t a r t i c l e i n f o article history: received march received in revised form april accepted may available online may keywords: autophagy myocardial ischemia/reperfusion injury autophagy is an intracellular process responsible for damaged or unnecessary protein and organelle degradation. in the heart, autophagy occurs at basal level and dysregulated autophagy is associated with a variety of cardiovas- cular diseases. autophagy is enhanced in ischemia as well as in the reperfusion phase during cardiac ischemia re- perfusion (i/r) injury. more importantly, recent studies revealed that autophagy exerted both beneficial and detrimental effects in pathology of cardiac ischemia reperfusion. this paper is to review the functional signifi- cance of autophagy in cardiac ischemia reperfusion injury and discuss underlying signaling pathways. this article is part of a special issue entitled: autophagy and protein quality control in cardiometabolic diseases. © elsevier b.v. all rights reserved. . introduction autophagy is a cellular process associated with damaged or unnec- essary protein and organelle degradation [ ]. previous evidences identi- fied autophagy as a protective intracellular process functioning as protein quality controller and cellular homeostasis keeper. however, a new type of cell death is proposed, namely “autophagic cell death” oc- curring with autophagy, indicating the complexity of autophagy func- tions [ , ]. in the heart, autophagy occurs at basal level under normal conditions, contributing to cellular homeostasis through cleaning long-lived or excessive proteins and aged organelles. deletion of au- tophagy can result in adverse effects in myocardium [ ]. in addition, al- tered autophagy was observed in many other cardiovascular diseases in response to pathological stimuli, including ischemic heart disease, car- diac hypertrophy and heart failure [ ]. there are basically three types of autophagy, namely, macroautophagy, microautophagy and chaperone-mediated autophagy (cma). these three types differed in ways by which unnecessary components are delivered into lysosomes for final degradation [ ]. macroautophagy, with typical formation of autophagosome, is the most characterized form of autophagy and is better illustrated in mammalian cells. macroautophagy is responsible for the degradation of both cytoplasmic proteins and intracellular organelles, including en- doplasmic reticulum (er) and mitochondria. notably, mitochondrial y and protein quality control in , chinese pla general hospital, autophagy is also termed as “mitophagy”, a process of selective clearance of damaged mitochondria. mitophagy is now considered as a protective mechanism during cardiac i/r injury, and we will discuss about it in the later part of this review. apart from the abovementioned three basic types of autophagy, yuuki fujiwara et al. reported two novel types of autophagy, termed as “rnautophagy” and “dnautophagy” [ , ]. in these two newly proposed autophagic pathways, rna or dna is directly taken in and degraded in lysosomes in an atp-dependent manner, mainly mediated by the lysosomal membrane protein of lamp c. however, the physiological function of rnautophagy or dnautophagy remains unclear. acute myocardial infarction (ami) is one of the major contributors of morbidity and mortality in patients with coronary heart diseases (chd) worldwide [ ]. under the condition of cardiac ischemia reperfu- sion injury (i/r injury), the process of autophagy is activated in response to energy crisis and oxidative stress. however, current researches demonstrate that autophagy can be a double-edged sword in the pathological process of i/r injury. in this review, we aimed to dis- cuss the complex functional contribution of autophagy in cardiac i/r injury and identify potential signaling molecules for future clinical development. . molecular signal alternation of autophagy during myocardial infarction and ischemia/reperfusion injury the heart is comprised of long-lived cardiomyocytes with little regenerative capacity. in myocardium, the self-digestive process of au- tophagy could occur under normal conditions at a low level, contribut- ing to cellular homeostasis through cleaning long-lived or excessive proteins and aged organelles. basal level of autophagy is fundamental for cardiac structure and function as for its essential role of protein and organelle quality control. loss of genes that are essential for http://crossmark.crossref.org/dialog/?doi= . /j.bbadis. . . &domain=pdf http://dx.doi.org/ . /j.bbadis. . . mailto:wind @gmail.com http://dx.doi.org/ . /j.bbadis. . . http://www.sciencedirect.com/science/journal/ s. ma et al. / biochimica et biophysica acta ( ) – autophagy could result in cardiac dysfunction and disorders. lamp and atg are essential mediator molecules for autophagy, deficiency of these genes leads to impaired autophagy, subsequent accumulation of abnor- mal substrates and cardiac dysfunction. clinical reports observed that mutations of lamp , a principle lysosomal membrane protein, were the cause of danon disease, a condition of severe and progressive myop- athy [ ]. in addition, k. nishida et al. reported that atg deficient mice hearts exhibited ventricular dilatation and dysfunction, accompanied by accumulation of damaged proteins and organelles [ ]. altered autophagy is involved in a great number of cardiovascular diseases such as dilated cardiomyopathy, heart failure, anticancer drug-induced cardiomyopathy or ischemic heart disease, autophagy is increased [ ]. decreased autophagic flux activity is observed in glycogen storage disease related cardiomyopathy, for instance, danon disease is characterized by abnormal accumulation of autophagosome due to de- fective autophagosome–lysosome fusion. autophagy is associated with multiple cardiovascular diseases, either as a detrimental contributor to the pathogenesis or as an adaptive response. however, it remains un- known whether the autophagic alteration in these cardiovascular disor- ders is adaptive or maladaptive. more preclinical studies and clinical analysis should be performed to address this. . . low atp level induced ampk activation upregulated autophagic pathways during cardiac ischemia phase cardiac ischemia is characterized by initial restriction of blood sup- ply and low atp generation, leading to imbalance between blood supply and energy demand, resulting in cardiomyocyte dysfunction and myo- cardial damage. adenosine monophosphate-activated protein kinase (ampk) is a sensitive sensor of cellular energy activated by the de- creased level of atp and high ratio of amp/atp under the condition of nutrient deprivation. during the initial phase of ischemia, ampk was activated by low atp level in cardiomyocytes. after activation, ampk regulates the induction of autophagy via direct or indirect ulk modifi- cations. previous studies reported that ampk activated autophagy through ampk-mtorc signaling: ampk inhibits mtorc through phosphorylation of tsc and raptor site, followed by the indirect acti- vation of ulk . moreover, recent studies revealed novel pathways through which ampk activated autophagy. ampk directly phosphory- lates and activated ulk , enabling the initiation of autophagy [ – ]. the association of ampk with autophagy during cardiac ischemia was further verified by the finding that autophagy in the initial phase of is- chemia was accompanied by ampk activation and was diminished by dominant negative ampk [ , ]. ampk is an essential molecule for au- tophagy initiation in cardiac ischemia. joungmok kim et al. found that ampk phosphorylation (ser and ser ) is required for ulk func- tion in glucose starvation induced autophagy [ , ]. ampk functions as a nutrient sensor in mediating autophagy machinery in response to energy crisis during cardiac ischemia. . . hypoxia and hif- α also participated in autophagy initiation in cardiac ischemia hypoxia-inducible factor alpha (hif- α) is a key molecule regulat- ing oxygen homeostasis. it could be activated by low oxygen or increased oxidative stress during cardiac i/r conditions, working potentially as a protective response. in vitro studies revealed that hif- α mediated mito- chondrial autophagy as an adaptive metabolic response under hypoxia conditions in mouse embryo fibroblasts, but the correlation between hif- α and autophagy in the disease model of cardiac i/r has not been il- lustrated [ ]. since previous researches confirmed that hif- α activation exerts cardio-protection during i/r, it will be interesting to figure out whether the beneficial effects of hif- α against cardiac i/r injury are partly mediated by autophagy in cardiomyocytes. . . beclin- mediated autophagy during cardiac reperfusion phase beclin (mammalian ortholog of yeast atg ) plays an essential role in mediating autophagy process, especially in the phase of reperfusion. since ampk is no longer activated in reperfusion, it is not the major mediator of autophagy in this phase. enhanced autophagy during reper- fusion is accompanied by upregulation of beclin instead of ampk, indi- cating that beclin- protein plays a vital role in autophagy in the phase of reperfusion [ ]. overexpression of beclin increased autophagic ac- tivity during i/r in vitro [ ]. conversely, depletion of beclin by sirna transfection or beclin mutation mice attenuated autophagic activity of cardiomyocytes during reperfusion [ ]. beclin is a key autophagic protein regulating both autophagosome formation and processing. collectively, the up-regulation of beclin is responsible for autophagy activation during reperfusion. however, the question on how cardiac i/r injury activates beclin remains to be elu- cidated. one possible mechanism is its association with bcl- protein. in vitro study revealed that beclin mediated autophagic response to nutrient deprivation in cardiac cells is modulated by bcl- protein [ ]. in addition, reactive oxygen species (ros) may also be a strong in- ducer of beclin- in mediating autophagy during reperfusion [ ]. in- stead of energy crisis, increased ros generation is a major promoter of autophagy during reperfusion. reperfusion phase causes increased oxi- dative stress and is accompanied by beclin overexpression. antioxi- dant mpg intervention significantly suppressed beclin up-regulation, suggesting that ros may play a key role in mediating beclin up- regulation [ ]. apart from regulating beclin expression, ros could ox- idize and decrease atg activity, contributing to lc lipidation and autophagy initiation [ ]. furthermore, as beclin is primarily located in er, whether er stress induced by reperfusion conditions also partic- ipates in beclin up-regulation needs further exploration. . . “impaired” autophagic flux in cardiac reperfusion phase autophagic flux is a dynamic cellular biological process, from the for- mation of autophagosome, autophagosome–lysosome fusion to final degradation. it has been deemed that autophagy is further enhanced during cardiac reperfusion phase by providing evidence for accumulat- ed autophagosomes in cardiomyocytes. however, we could not exclude the possibility that the increased formation of autophagosomes during i/r was resulted from decreased autophagosome clearance. interesting- ly, x. ma et al. recently proposed a novel view that autophagic flux was partly “impaired”, instead of “excessively activated” during the phase of reperfusion. they found that autophagosome clearance was dramatical- ly decreased with reperfusion in cardiomyocytes, which is detrimental to cardiomyocyte survival during reperfusion [ , ]. this is a novel dis- covery that is contrary to our traditional view that autophagy is further enhanced during reperfusion phase. this finding also gives rise to the importance of detecting “intact autophagic flux” to reveal the accurate level of autophagy. additionally, it is of necessity that researchers re- evaluate the previously published results in which pure autophagosome abundance was used to reflect the extent of autophagic activity. . double-edged sword biological function of autophagy in myocardial i/r injury . . autophagy mediated atp generation alleviates energy crisis during myocardial ischemia phase sufficient atp supply is an essential requirement for constitutively contrasting cardiomyocytes. however, during the phase of ischemia, atp generation is decreased due to damaged mitochondrial function and uncoupled phosphorylation. decreased atp level is an indirect inducer of cardiomyocyte autophagy via ampk activation. low atp level is capable of activating the energy sensor ampk, followed by up-regulation of ampk-mtorc -ulk signaling and autophagy s. ma et al. / biochimica et biophysica acta ( ) – initiation. in the degradation process of autophagy, free fatty acids and amino acids are released, and subsequently recycled to generate atp through tricarboxylic acid cycle (tca cycle), compensating for the energy crisis in the condition of cardiac ischemia. it was con- firmed that inhibition of autophagy with -ma decreased atp gener- ation and aggravated cardiac cell death in response to glucose deprivation [ ]. cardiac autophagy serves as an energy-recovering process during ischemic phase and is essential for cardiomyocyte survival. . . mitophagy compensates for mitochondrial injury during cardiac i/r during the process of cardiac i/r, mitochondrial fission and fragmen- tation are observed in cardiomyocytes [ , ]. excessive dysfunctional and damaged mitochondrial during i/r would cause inflammation re- sponse and ros over-production, resulting in myocardial cell death [ ]. under this condition, autophagy is induced to remove the dysfunc- tional mitochondrial, a process known as mitochondrial autophagy, namely, mitophagy [ , ]. during the initial phase of ischemia, the ac- tivation of autophagy functions primarily to maintain energy balance through recovering atp generation, whereas to switch to damaged or- ganelle or protein clearance in the later phase of ischemia and reperfu- sion. undoubtedly, mitophagy is a protective form of autophagy during i/r injury, preventing damaged mitochondrial from releasing cytotoxic substances. . . autophagy contributes to proteostasis in i/r injury there are basically two cellular processes responsible for protein quality control through removal of aged or damaged proteins: autoph- agy for long-lived and macromolecular proteins, while ubiquitin protea- some system (ups) for short lived proteins [ ]. nevertheless, during the process of i/r, ups becomes dysfunctional (proteasome activity is preferentially reduced, ubiquitinated proteins exceed the degradation ca- pacity of proteasome), leading to increase in myocardial ubiquitinated proteins and resultant protein aggregates [ ]. unlike ups, autophagy is activated after i/r, partly functioning to remove these cytotoxic ubiquitinated proteins. findings by tannous, p. et al. demonstrated that autophagic activity attenuated protein aggregation in myocardium [ ]. conversely, ubiquitinated proteins were increased in the myocardium of cardiac-specific atg -deficient mice [ ]. ups and autophagy work apelin ampk-mtor-ulk signaling ischemia protetive autophagy adm fig. . mechanisms and functions of autophag cooperatively in protein quality controlling. under the condition of cardi- ac i/r, increased autophagic activity compensated for the impaired ups function, keeping proteolysis at an appropriate level. . . detrimental effects of autophagy during reperfusion current researches demonstrate that autophagy can be a double- edged sword in the pathological process of i/r injury [ ]. beneficial functions of autophagy during i/r could be attributed to atp generation and cellular homeostasis, but the underlying mechanisms of detrimen- tal effects of autophagy in reperfusion are still unclear. uncontrolled excessive induction of autophagy in response to i/r in- jury may contribute to autophagic cardiomyocyte death, evidenced by the observation that autophagy suppression by -ma or beclin sirna reduced cell death in cardiomyocyte i/r injury [ ]. autophagy is a cellular process responsible for substrate degradation. if autophagy is hyper-activated beyond a certain level to delete necessary proteins or organelles, leading to cellular dysfunction, autophagic cell death would occur. another reason for the detrimental effects of autophagy may be attributed to the crosstalk between autophagy and apoptosis. as bcl- inhibits beclin -dependent autophagy, beclin mediated autophagy ac- tivation during reperfusion is associated with bcl- down-regulation. notably, bcl- protein also participates in the regulation of apoptosis. decreased expression of bcl- may contribute to apoptotic cell death. another potential molecule that connects autophagy and apoptosis is bnip , a pro-apoptotic member of bcl- family. studies demonstrated that bnip- is involved in autophagy upregulation in cardiac i/r [ ]. however, it still remains to be clarified, whether bnip mediated au- tophagy activation contributes to autophagic cardiomyocyte death, or this autophagy opposes apoptotic cell death pathway. . potential therapeutic targets of autophagy for cardiac i/r injury it has been a consensus that cardiac autophagy is involved in the pathological progress of cardiac i/r. therefore, autophagy has become a potential therapeutic interest for researchers. even though there are no clinical trials targeting autophagy in cardiac i/r treatment, several molecular pathways have been explored in preclinical studies. akt-bcl -beclin signaling reperfusion excessive autophagy scs y in cardiac ischemia/reperfusion injury. ischemia reperfusion low atp level hypoxia ampk hif- α decreased bcl- expression reactive oxygen species beclin autophagy activation mitophagy restored atp generation proteostasis association with apoptosis excessive deletion of proteins or organelles fig. . dual regulative effects of apelin in adipose derived mesenchymal stem cell (admsc) autophagy in hypoxia–reoxygenation (h/r). our recent findings indicate that apelin is capable of dually regulating the activity of autophagy, improving cell viability of admscs. in the phase of initial anoxia, apelin up-regulated protective autophagy through the activation of ampk- mtor-ulk pathway, while in the period of reoxygenation, apelin suppressed excessive autophagic activity through akt-bcl -beclin signaling. the dual regulative effects of apelin through different signaling mechanisms keep admsc autophagy activity at a moderate level to be protective for cell survival. s. ma et al. / biochimica et biophysica acta ( ) – . . ampk activation could induce autophagy and exert cardioprotective effects against i/r as increasing lines of evidence have verified that ampk activation during the initial phase of cardiac ischemia contributes to protective au- tophagy, pharmacologic drugs for ampk activation are increasingly at- tractive as therapeutic targets. in vitro evidence showed that ampk activation by acetylcholine elicited autophagy and induced tolerance against h c cell h/r injury [ ]. d , a cell-permeable compound could also activate ampk, induce autophagy and exert cardioprotective effects against i/r [ ]. a great number of clinical drugs have been shown to activate ampk, for instance, d , metformin and stains [ ]. these pharmacological compounds may activate ampk through the regulation of amp/atp ratio indirectly. additionally, agnes s. kim et al. reported that a directing ampk activation via small molecule a- significantly alleviated cardiac i/r injury in vivo and they demonstrated that pre-treatment of ampk activation was sufficient to replicate the beneficial function of ischemic preconditioning [ ]. even though ampk mediated autophagy is protective in cardiac i/r, some concern still remains. one point is that ampk activation could stimulate fatty acid metabolism while reduce glucose oxidation, resulting to less efficient myocardium metabolism. moreover, using drugs to activate ampk systemically may possibly increase food intake by hypothalamus stimuli. further studies should be directed to under- stand the feasibility of ampk activation in cardiac i/r treatment. . . autophagy regulation through selective activation of mtor system is associated with enhanced cardiac cell survival after i/r mammalian target of rapamycin (mtor) is a serine/threonine ki- nase, associating with specific adaptor proteins to form types of multiprotein complexes, mtor complex (mtorc ) and mtor com- plex (mtorc ) [ ]. wu, x. et al. reported that valsartan precondi- tioning significantly reduced cardiac infarction size through autophagy up-regulation via pi k-akt-mtorc pathway [ ]. however, toshinori aoyagi et al. recently reported that overexpression of cardiac mtorc protected the heart from i/r injury [ ]. this seems to be a contradiction to our conclusions as mtorc overexpression would suppress the pro- survival process of autophagy in myocardium. in fact, the beneficial ef- fects of mtorc over-expression are mainly attributed to the suppres- sion of inflammatory response during reperfusion, and the benefits of decreased inflammatory response exceed the functional loss of autoph- agy. these finding also indicates the complexity of mtorc function in a particular disease modal. a specific molecule may be associated with a variety of cellular pathways and have multiple functions. a comprehen- sive study and evaluation of mtorc should be illuminated before clin- ical usage for autophagy regulator in cardiac i/r patients. additionally, we recently uncovered some interesting findings in the regulative function of apelin on adipose derived mesenchymal stem cell (admsc) autophagy in the disease model of hypoxia–reoxygenation (fig. ). similar with cardiac i/r injury, admsc autophagy is activated in the initial hypoxia phase and excessively enhanced in the period of reoxygenation. notably, apelin is capable of dually regulating the activ- ity of autophagy, improving cell viability of admscs. in the phase of initial anoxia, apelin up-regulated protective autophagy through the ac- tivation of ampk-mtor-ulk pathway, while in the period of reoxy- genation, apelin suppressed excessive autophagic activity through akt-bcl -beclin signaling. the dual regulative effects of apelin through different signaling mechanisms keep admsc autophagy activity at a moderate level to be protective for cell survival. our in vitro results bring some illumination to the therapies on cardiac i/r injury. it is inter- esting to find a pharmacological regulator to adjust cardiac autophagy to a moderate extent, thus exerting protective effects during the period of both ischemia and reperfusion. interestingly, researchers found that the activation of mtorc also participated in the induction of autophagy, and was associated with en- hanced cardiac cell survival after i/r [ ]. recently, völkers, m. et al. pro- posed a novel approach for cardiac ischemia by selectively increasing s. ma et al. / biochimica et biophysica acta ( ) – mtorc while inhibiting mtorc signaling [ ]. this indicates that moderate regulation of autophagy, via either pi k-akt-mtorc path- way or mtorc /mtorc balancing, may serve as a potential strategy in cardiac i/r treatment (fig. ). . . other potential agents targeting autophagy for cardiac i/r injury a series of preclinical studies have revealed the potential cardioprotective benefits of histone deacetylase (hdac) inhibitors in myocardial i/r model. in a recent study by min xie et al., they uncovered that autophagic flux in myocardium infarct border zone was required for the cardio-protective activity of hdac inhibitor, suberoylanilide hydroxamic acid (saha) [ ]. saha has been approved for cancer treatment by the us food and drug administration. their study demon- strates that autophagy activation by saha pretreatment or saha treat- ment during reperfusion is beneficial for cardiac i/r. more importantly, this study was performed with a preclinical trial in a large-animal of rabbits, using several clinical trial methodologies such as randomiza- tion, pre-established end points and strict blinding of personnel. as saha serum concentrations in rabbits are achievable in human sub- jects, saha was shown as a potential agent for its control of cardiomyo- cyte autophagy. however, safety is an important issue that should be addressed. before it will eventually be applied as a therapeutic strategy in clinical i/r injury, pharmaceutic side effects of saha and its molecu- lar mechanisms of its association with cardiomyocyte autophagy should be fully understood. . summary currently, the consensus is emerging that autophagy activation dur- ing cardiac i/r could either antagonize cardiac pathogenesis or contrib- ute to further myocardium damage, but the underlying mechanism is still unclear. the debate focuses on the detrimental effects of autophagy in i/r. one hypothesis is that excessive autophagy aggravates tissue damage during the period of reperfusion when the heart is load- stressed, accompanied with over-deletion of key organelles or proteins in cardiomyocytes. besides, some researchers attributed the detrimen- tal effects of autophagy to its association with apoptosis. several drugs targeting the key molecular of autophagy such as mtor or beclin- have been applied, for the purpose of alleviating i/r injury in myocardi- um by regulating the process of autophagy. the key is to suppress exces- sive autophagy without eliminating basal autophagy, tuning autophagic activity within moderate range for therapeutic benefit in cardiac i/r. in future studies, understanding the function and molecule machinery of autophagy in cardiac i/r injury and exploring potential therapeutic tar- gets of autophagy have significant clinical implications. acknowledgment this work was supported by national natural science foundation of china (no. , , ), fcao (bws j ); inno- vation team development grant by china department of education (irt ); shaanxi province science technological research found k - - . references [ ] n. mizushima, b. levine, a.m. cuervo, d.j. klionsky, autophagy fights disease through cellular self-digestion, nature ( ) – . 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[ ] a.s. kim, e.j. miller, t.m. wright, j. li, d. qi, k. atsina, v. zaha, k. sakamoto, l.h. young, a small molecule ampk activator protects the heart against ischemia–reperfusion injury, j. mol. cell. cardiol. ( ) – . [ ] m. laplante, d.m. sabatini, mtor signaling in growth control and disease, cell ( ) – . [ ] x. wu, l. he, y. cai, g. zhang, y. he, z. zhang, x. he, y. he, g. zhang, j. luo, induction of autophagy contributes to the myocardial protection of valsartan against ische- mia–reperfusion injury, mol. med. rep. ( ) – . [ ] t. aoyagi, y. kusakari, c.y. xiao, b.t. inouye, m. takahashi, m. scherrer- crosbie, a. rosenzweig, k. hara, t. matsui, cardiac mtor protects the heart against ischemia–reperfusion injury, am. j. physiol. heart circ. physiol. ( ) h –h . [ ] n. gurusamy, i. lekli, s. mukherjee, d. ray, m.k. ahsan, m. gherghiceanu, l.m. popescu, d.k. das, cardioprotection by resveratrol: a novel mechanism via autophagy involving the mtorc pathway, cardiovasc. res. ( ) – . [ ] m. volkers, m.h. konstandin, s. doroudgar, h. toko, p. quijada, s. din, a. joyo, l. ornelas, k. samse, d.j. thuerauf, n. gude, c.c. glembotski, m.a. sussman, mechanis- tic target of rapamycin complex protects the heart from ischemic damage, circu- lation ( ) – . [ ] m. xie, y. kong, w. tan, h. may, p.k. battiprolu, z. pedrozo, z.v. wang, c. morales, x. luo, g. cho, n. jiang, m.e. jessen, j.j. warner, s. lavandero, t.g. gillette, a.t. turer, j.a. hill, histone deacetylase inhibition blunts ischemia/ reperfusion injury by inducing cardiomyocyte autophagy, circulation ( ) – . http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf 	the role of the autophagy in myocardial ischemia/reperfusion injury 	 . introduction 	 . molecular signal alternation of autophagy during myocardial infarction and ischemia/reperfusion injury 	 . . low atp level induced ampk activation upregulated autophagic pathways during cardiac ischemia phase 	 . . hypoxia and hif- α also participated in autophagy initiation in cardiac ischemia 	 . . beclin- mediated autophagy during cardiac reperfusion phase 	 . . “impaired” autophagic flux in cardiac reperfusion phase 	 . double-edged sword biological function of autophagy in myocardial i/r injury 	 . . autophagy mediated atp generation alleviates energy crisis during myocardial ischemia phase 	 . . mitophagy compensates for mitochondrial injury during cardiac i/r 	 . . autophagy contributes to proteostasis in i/r injury 	 . . detrimental effects of autophagy during reperfusion 	 . potential therapeutic targets of autophagy for cardiac i/r injury 	 . . ampk activation could induce autophagy and exert cardioprotective effects against i/r 	 . . autophagy regulation through selective activation of mtor system is associated with enhanced cardiac cell survival after i/r 	 . . other potential agents targeting autophagy for cardiac i/r injury 	 . summary 	acknowledgment 	references journal of health science, ( ) – ( ) population is a critical factor for global carbon dioxide increase kikuo onozaki∗ department of molecular health sciences, graduate school of pharmaceutical sciences, nagoya city university, mizuho-ku, tanabe-dori – , – , japan (received august , ; accepted october , ; published online november , ) based on intergovernmental panel on climate change (ipcc) assessment report at , it is likely that there has been a substantial anthropogenic con- tribution to global warming. carbon dioxide (co ) is a major anthropogenic greenhouse gas and its in- crease is thought to give rise to the recent global warming. although studies suggested the impact of population growth on carbon dioxide increase, much attention has not been paid. in this study population was plotted as compared to the atmospheric co con- centration. a quite linear relationship was observed between population and co concentration at both before and after , after which the global temper- ature rapidly increased. in addition, direct and indi- rect human-derived co emission appeared to con- tribute much to the total amount of co emission in developing countries and as the economy grow fossil- fuel-derived co emission increased more as com- pared to human-derived emission. these findings in- dicate that population growth especially in develop- ing countries is a critical factor for manipulation of global co increase. key words —— population, carbon dioxide, global warming introduction global warming is a serious issue for human be- ings. the th intergovernmental panel on climate change (ipcc) assessment report at indicated that carbon dioxide (co ) has increased markedly as a result of human activities since and now far exceed pre-industrial values, and the amount of ∗to whom correspondent should be addressed: department of molecular health sciences, graduate school of pharmaceuti- cal sciences, nagoya city university, mizuho-ku, tanabe-dori – , – , japan. tel. & fax: + - - - ; e-mail: konozaki@phar.nagoya-cu.ac.jp co in the atmosphere in ( ppm) exceeds by far the natural range of the last years ( – ppm). ) co is a major anthropogenic green house gas, which is believed to contribute to the global warming. human activities require energy for essentials of life such as clothing, food, housing and so on, which require co emission. the human activities increase as the growth of population. studies sug- gested that population growth is one of the major factors for co emission in both developed and de- veloping countries. – ) it has been also suggested that rising income levels have been associated with the increased co emission. ) however, still much attention has not been paid for the population. in this study the impact of population on co increase in atmosphere was determined. the study indicates that population growth is closely associated with the increase of co in atmosphere, and suggests that population growth in developing countries is a crit- ical factor for manipulation of global co increase. materials and methods population is based on united nations (un) world population prospect: the revision. global temperature ( -year mean) is based on national aeronautics and space administration/ earth system research laboratory (nasa/esrl). the atmosphere co concentration is based on nasa/esrl and carbon dioxide information analysis center (cdiac). the amount of co emission of is based on cdiac. results and discussion population was plotted as compared to the at- mospheric co concentration and global atmo- spheric temperature (fig. ). the temperature in- dicates -year mean surface temperature anomaly relative to – mean. almost all the plots were closely associated with co concentration. in- terestingly these associations were observed at both before and after . before , co concen- tration does not fit with the global temperature, but after the temperature rapidly increased with concurrent increase of co . a quite linear rela- tionship was observed between population and co concentration (fig. ). it is of note, however, that af- ter , whose population was billion, the slope vol. ( ) fig. . comparison between population, global temperature and atmospheric co concentration fig. . relationship between population and atmospheric co concentration fig. . comparison of the amount of co emission from human (direct and indirect) and fossil-fuel among developing and devel- oped countries human-derived co was estimated by the report of prairie and duarte. ) was steep as compared to s from , whose population was billion. this difference could be due to social events like wars, energy crisis, saving energy, economical growth and so forth. these find- ings strongly support the notion that natural factors, such as volcanic activity, do not much contribute to the co increase. ipcc indicated that most of the anthropogenic co is derived from fossil fuel use and changes in land use. ) however, it is reported that direct and indirect metabolic co release by no. humanity much contributes to the co emission. direct metabolic co is comprised of respiration of humans, and indirect co is composed of the de- composition of their resulting wastes, and respira- tion and resulting decomposition from a large live- stock population to feed themselves as well as a large number of domestic animals. the direct and indirect metabolic co release from humans ( . giga ton carbon (gtc)) assessed at reaches up to % of the total co emission ( . gtc) from fossil fuel consumption and changes in land use at – . ) this amount cannot be overlooked. next, the amount of co emission from human (di- rect and indirect) and fossil-fuel was compared be- tween developing (china and india) and developed countries (america and japan, fig. ). in china, be- fore human-derived emission was larger than fossil-fuel-derived emission. after fossil-fuel- derived emission exceeded human derived emission and it rapidly increased as compared to that of hu- man derived emission. in india, up to human- derived emission was larger than that of fossil- fuel-derived emission although the latter rapidly in- creased. in both america and japan, human-derived emission was quite small as compared to that of fossil-fuel-derived emission, and total amount of emission reached almost plateau. these results indi- cate that human-derived co emission contributes much to the total amount of co emission in de- veloping countries and that as the economy grow fossil-fuel-derived co emission increases more as compared to human-derived emission. when the fossil-fuel-derived emission per capita was com- pared among these countries at , those of china ( . metric tons of carbon per capita), india ( . ) were smaller than those of america ( . ) and japan ( . ). in addition, rising income levels have been associated with the increased co emission. ) currently a large number of people are living in de- veloping countries and their numbers are increas- ing, consequently as the economy grow, in other words as the co emission per capita increases, more and more co will be emitted. if we want american and japanese like life-style at by limiting co emission at the level of , where global temperature was not steeply increased, the population should be . and . billion, respec- tively. therefore, more attention should be paid for the population growth to reduce the atmosphere co increase. references ) le treut, h., somerville, r., cubasch, u., ding, y., mauritzen, c., mokssit, a., peterson, t and prather, m. ( ) historical overview of climate change. in: climate change : the physical science ba- sis. contribution of working group i to the fourth assessment report of the intergovernmental panel on climate change [solomon, s., qin, d., manning, m., chen, z., marquis, m., averyt, k. b., tignor, m. and miller, h. l. (eds.)]. cambridge university press, cambridge, united kingdom and new york, ny, usa. ) birdsall, n. ( ) another look at population and global warming. policy research working papers, no. , washington d.c., the world bank. ) engleman, r. ( ) stabilizing the atmosphere: population, consumption, and greenhouse gases, washington, d.c., population action international. ) royal society of london and u.s. national academy of sciences ( ) population growth, resource consumption and a sustainable world, washington, d.c., u.s. national academy of sci- ences. ) anqing, s. ( ) population growth and global carbon dioxide emissions. http://www.iussp.org/ brazil /s /s shi.pdf ) prairie, y. t. and duarte, c. m. ( ) direct and in- direct metabolic co release by humanity. biogeo- sciences, , – . the tentative idea of energy recovery based on “ râ€? principle procedia engineering ( ) – - © published by elsevier ltd. doi: . /j.proeng. . . available online at www.sciencedirect.com available online at www.sciencedirect.com procedia engineering ( ) – procedia engineering www.elsevier.com/locate/procedia international conference on green buildings and sustainable cities the tentative idea of energy recovery based on " r" principle ye shuangguia∗, jiang baoguoa, li chunb awuhan university of technology, wuhan city, , china bjianghan university, wuhan city, , china abstract starting from the current situation of the energy crisis, this paper analyzes the pros and cons of two ways to solve energy issues, and indicates that energy conservation plays an important sole in solving energy problems. around the " r" principles in green design, this paper discusses the " r" thought of energy recovery. finally, through the tentative plan of one practical case, it demonstrates the great application prospect of the " r" idea in the energy recovery. © published by elsevier ltd. selection and/or peer-review under responsibility of apaas keywords: energy crisis; energy recovery; " r" principle; . introduce th century, the invention of the steam engine opens the door to modern industry. with the continuous development of science and technology, steam engines had been replaced by internal combustion engines. but no matter how the development of technology, there is one thing that has not changed - the high dependence of industry on energy. in general, the whole modern industry is a machine driven by energy. since the industrial revolution, modern industry has made rapid development. however, the costs of development are the uncontrolled consumption of energy on coal, oil, gas and other natural energy. the consequences of excessive consumption of natural energy, on the one hand, it caused the energy crisis, which restricted the development of human society and economy; the other hand, the perennial use of fossil fuels caused the greenhouse effect and environmental pollution, threatening human survival. ∗ corresponding author. tel.: + - - - e-mail addresses: yeshuanggui@ .com open access under cc by-nc-nd license. open access under cc by-nc-nd license. http://creativecommons.org/licenses/by-nc-nd/ . / http://creativecommons.org/licenses/by-nc-nd/ . / ye shuanggui et al. / procedia engineering ( ) – ye shuanggui, jiang baoguo and li chun / procedia engineering ( ) – so, throughout the development of the whole community, whether oil shortage, or environment damage, energy will be a stumbling block to the sustainable development of society, so the problems of energy will be undoubtedly imminent. . the energy problems energy resources as the carrier of energy, in fact, to solve the energy problem is to solve the problem of energy production or source. . . the two ways to solve the energy problem since the energy of universe observes the law of energy conservation, there are two main ways to solve the current energy problems: first, the development of new energy sources, using other forms of energy which have not be developed, such as solar, wind, biomass, geothermal, ocean energy, nuclear energy, hydrogen energy and other energy; the second is to save energy, reducing the energy consumption in the process of production or life, recycling and reusing the energy consumed in the process of using, for example, lead the natural light into the indoor, reduce the use of interior lighting, and convert the energy lost by braking the car into the electrical energy for automotive lighting. . . compare the merits of two ways the development of new energy sources is of course the best way to solve the energy crisis. among the many new energy sources, solar and nuclear energy is undoubtedly the best choice. solar energy has heat energy and light energy, which can be directly used or be converted into electrical energy. however, the use of solar energy is often affected by time and weather change. solar energy can generate electricity during the day but not rainy days, so it is difficult to ensure continuous power supply. compared with other energy sources, the current investment of solar power costs to million / kw, or even higher. in the process of solving the energy crisis, high hopes have been given to the nuclear power. in fact, since when soviet union ran its first nuclear reactor, the use of nuclear energy has always been restricted by the nuclear leaks and nuclear pollution. since that time, the major nuclear accidents have happened three times: the three mile island nuclear accident of u.s. in ; the chernobyl nuclear accident soviet union in , and the fukushima nuclear power plant accident not long ago. the leakage of nuclear and nuclear pollution caused by the earthquake in japan warned the whole world that nuclear power should be used carefully. as for the development of other new energy sources, there are also many constraints: it often costs a very long time from the development of a new energy to final application to life. a slow remedy can not meet an emergency. what is more, it may damage the ecological environment and threat human survival. in fact, as long as the sun existing, the earth constantly rotating, energy will not die out. the energy is ubiquitous in our lives. the key is how to effectively collect these scattered energies? "design" provides the best answer to solve this problem. back in ancient china, people have a design consciousness to use the natural power, such as waterwheel and windmill in ancient china. today, design is widely used in every corner of life. carefully conceiving, people have designed a lot of products which can recycle and reuse energy, such as the floor that can transform the pressure of human activities into electricity; the shoes charger that can recycle the energy during walking. compared to the development of new energy sources, the ways of design to save energy is easier to implement, and the cost is relatively low. the recovery process will not damage the ecological ye shuanggui et al. / procedia engineering ( ) – ye shuanggui, jiang baoguo and li chun / procedia engineering ( ) – environment. in addition, as long as making full use of this approach, the collected energy is considerable. thus, the design in solving the problem of energy recovery has far-reaching prospects. in particular, the concept of green design is proposed, which provides us with a set of methods that can be used as a reference. . the idea of energy recovery based on " r" principle . . the origin of " r" principle the so-called " r" principles, namely: reduce, recycle and reuse, which is firstly proposed to solve the solid waste management. as the whole process of design, production and manufacture is closely related with the waste generation, it is introduced to these fields. as the core part of product development, the phase of design directly restricts the phases of production and manufacturing. thus, it is an important target of green economy to initiate " r" principle in the design field. the " r" principle of green design is accompanied by the development of green economy. it is expected to build a coordinated development mechanisms among the people - society - environment by design thinking to reduce the waste of the world's resources. . . the idea of energy recovery based on the " r" principle from the generation, development and application of the " r" principles, we can see that its aim is to handle the relationships of the sustainable development and nature. therefore, " r" principles have an important reference for solving the energy problems. through the ways of reducing, recycling and reusing, we can effectively collect the scattered energy in life for reusing, which is indirect to achieve the purpose of producing energy. . . . reduce reduce the use of unnecessary energy, or maximize energy. there are many situations in life that we can achieve the energy conservation by developing good habits or using new technological means, such as developing the habit of turning off lights at home or in public places; using the compact fluorescent lamps to replace the traditional lighting facilities; using natural light to replace the part of the interior light; using electric vehicles instead of conventional gasoline vehicles to improve energy efficiency. . . recycle recycle the energy. there are two main ways to recycle energy: first, to further enhance the conversion of the natural renewable energy, such as wind, hydro, solar.; the second is to recycle the energy consumed in the production process, such as haier family cycling energy center can recycle the waste heat which is exhausted to the outside from air condition, and transform it into hot water to meet the purposes of family bath or kitchen washing. . . . reuse reuse the energy by collecting and processing the carrier of the energy in order to achieve the new energy. in use, energy is always in constant movement and change. by processing the energy carrier, we can again gain energy, such as: turn sour the plant stems and leaves or straw to produce biogas, satisfying the daily need for electricity. another example, collect the garbage or waste by category to release the energy by processing, turning waste into treasure. ye shuanggui et al. / procedia engineering ( ) – ye shuanggui, jiang baoguo and li chun / procedia engineering ( ) – . the tentative plan of energy recovery based on " r" principle as aesthetic, life does not lack beauty but a lack of vision, so as well as energy. in our lives, although energy is invisible and intangible, it does always be with us, hand in hand. however, we are too accustomed to the surrounding environment not to consider the existence of energy. when you think about it consciously, you will find that we can collect the energy for reusing in many places of our life. all we should have this kind of life experience: standing near the bus station or train tracks, when the car or train passing, you will obviously feel there is a cool breeze going from your (fig. ). why is that? how so? fig. . some occasion where energy can be recovered in fact, this is caused by the friction between car and the air. in this process, in order to overcome the resistance of the air, car loses some of the energy to form the winds. in the subway or tunnels, vehicles coming and going, it goes on the conversion of energy between the air and the vehicle. according to the related technologies of wind power, we can install the generation equipment of wind power on both sides of the tunnel, which will convert the energy lost by overcoming the resistance of the air into electricity for lighting in these areas (fig. ). fig. . the diagram of recycling energy model . the summary energy as the driving force of the world economic development, if the problem of energy crisis is not ye shuanggui et al. / procedia engineering ( ) – ye shuanggui, jiang baoguo and li chun / procedia engineering ( ) – resolved, the development of the world economy will face the danger of stagnation. however, the development of new energy sources is not necessarily the most effective way to solve the problem. to fundamentally solve the problem, we have to return to the source of the problem - the production and the life. using the " r" principles, we can effectively recover the energy in our daily life to meet the part need of producing and living. by this way, we can find an effective way to reduce the consumption of fossil fuel and to solve the energy crisis and ecological issues. references [ ] (u.s.) li po ed. li wei translate. the coming energy crash. renmin university of china press; . [ ] dong chongshan ed. deadlock and breakthrough - the general crisis of human energy and its way out. people's publishing house; . [ ] zong min ed. principles of green building design. china architecture and building press; . [ ] beijing fang liang culture communication co. ltd. ed. the green building design of the world. china architecture and building press. . [ ] "green future series" edited by the editorial board. "green future" series: the urban life of future: the living environment and green homes. world publishing company; . genome sequence of enterobacter cloacae subsp. dissolvens sdm, an efficient biomass-utilizing producer of platform chemical , -butanediol youqiang xu,a ailong wang,a fei tao,b fei su,b hongzhi tang,b cuiqing ma,a and ping xua,b state key laboratory of microbial technology, shandong university, jinan, people’s republic of china,a and state key laboratory of microbial metabolism, shanghai jiao tong university, shanghai, people’s republic of chinab enterobacter cloacae subsp. dissolvens sdm has an extraordinary characteristic of biomass utilization for , -butanediol pro- duction. here we present a . -mb assembly of its genome. the key genes for regulation and metabolism of , -butanediol pro- duction were annotated, which could provide further insights into the molecular mechanism of high-yield production of , -butanediol. the energy crisis of recent years shows the shortage of nonre-newable resources such as crude oil ( , ). with growing demand for nonrenewable resources and their shortage, biological production of fuels and chemicals from renewable resources has gained great attention ( ). , -butanediol ( , -bd) is a useful chemical that can be produced from renewable resources ( , ). it is an important platform compound, which could be used to produce a series of useful products, such as methyl ethyl ketone and , -butadiene ( , ). microbial production of , -bd has a long history (over years) ( ). various bacteria were used to produce , -bd ( , , , , ). however, there has been only one report related to , -bd production by an enterobacter strain, and the production yield was very low ( ). the enterobacter cloacae subsp. dissolvens sdm (cgmcc ) strain isolated from soil samples is a potential industrial candidate for , -bd production ( ), which could produce more than g liter� , -bd from glucose. moreover, strain sdm has an extraordinary characteris- tic of biomass utilization for , -bd production. this strain could efficiently use pentose sugars, xylose, and arabinose from ligno- cellulose and other cheap biomass, such as cassava, one of the most efficient crops in terms of carbohydrate production ( ) for , -bd production (unpublished results). here we determined a draft genome sequence of strain sdm. the genome sequence was determined by genome sequencer ( gs flx) ( ). the genome sequence contains , reads with an average length of bp at more than -fold coverage with the g�c content of . %. the reads were assembled using the newbler as- sembler ( life science) into large contigs (� bp) with a length of , , bp. the genome sequence was annotated by the rast server ( ). trnas were predicted by trnascan-se v. . ( ), and rrnas were found with the rnammer . ( ). the genome sequence of strain sdm contains , protein- coding sequences (cdss). three rrnas and trnas were iden- tified. seventeen cdss for the metabolism of pentose sugars from biomass are annotated, which are related to the complete pentose metabolic pathway, including subpathways of phosphoketolase and transketolase/transaldolase. this metabolism is important for pentose utilization in the industrial application. in addition, there are cdss for utilization of other carbohydrates, indicating that strain sdm may have a wide substrate spectrum. the se- quence contains the complete operon ( cdss) and key coding genes ( cdss) for , -bd metabolism, which could provide further insights into efficient biomass utilization for the pro- duction of , -bd. the genome sequence also contains a series of membrane transport systems, including cdss involved in atp-binding cassette (abc) transporters. the abc transport- ers play important roles in not only accumulating compatible solutes and substrates but also excreting unwanted products ( ). it may be an important reason for the high-yield produc- tion of , -bd. nucleotide sequence accession numbers. the whole-genome shotgun sequence has been deposited at ddbj/embl/genbank under accession number agsy . the version described in this paper is the first version, with accession number agsy . acknowledgments we thank huajun zheng and his colleagues for genome sequencing per- formed at the chinese national human genome center in shanghai, people’s republic of china. this work was supported by grants from the national natural science foundation of china ( , , and ) and the chi- nese national program for high technology research and development ( aa a ). references . aziz rk, et al. . the rast server: rapid annotations using subsystem technology. bmc genomics : . . celińska e, grajek w. . biotechnological production of , - butanediol— current state and prospects. biotechnol. adv. : – . . ji xj, et al. . enhanced , -butanediol production by klebsiella oxy- toca using a two-stage agitation speed control strategy. bioresour. tech- nol. : – . . ji xj, huang h, ouyang pk. . microbial , -butanediol production: a state-of-the-art review. biotechnol. adv. : – . received november accepted november address correspondence to cuiqing ma, macq@sdu.edu.cn, or ping xu, pingxu@sjtu.edu.cn. y. xu, a. wang, and f. tao contributed equally to this article. copyright © , american society for microbiology. all rights reserved. doi: . /jb. - genome announcement - / /$ . journal of bacteriology p. – jb.asm.org o n a p ril , a t c a r n e g ie m e l l o n u n iv l ib r h ttp ://jb .a sm .o rg / d o w n lo a d e d fro m http://dx.doi.org/ . /jb. - http://jb.asm.org http://jb.asm.org/ . lagesen k, et al. . rnammer: consistent and rapid annotation of rrna genes. nucleic acids res. : – . . li l, et al. august . biocatalytic production of ( s, s)- , -butanediol from diacetyl using whole cells of engineered escherichia coli. bioresour. technol. doi: . /j.biortech. . . . [epub ahead of print]. . liu z, et al. . production of ( s, s)- , -butanediol and ( s)-acetoin from glucose using resting cells of klebsiella pneumoniae and bacillus sub- tilis. bioresour. technol. : – . . lowe tm, eddy sr. . trnascan-se: a program for improved detection of transfer rna genes in genomic sequence. nucleic acids res. : – . . ma c, et al. . enhanced , -butanediol production by klebsiella pneumoniae sdm. appl. microbiol. biotechnol. : – . . margulies m, et al. . genome sequencing in microfabricated high- density picolitre reactors. nature : – . . peters d. . raw materials. adv. biochem. eng. biotechnol. : – . . poolman b. . transporters and their roles in lab cell physiology. antonie van leeuwenhoek : – . . ragauskas aj, et al. . the path forward for biofuels and biomaterials. science : – . . saha bc, bothast rj. . production of , -butanediol by newly iso- lated enterobacter cloacae. appl. microbiol. biotechnol. : – . . wang a, et al. . production of , -butanediol from corncob molas- ses, a waste by-product in xylitol production. appl. microbiol. biotechnol. : – . . zhang l, et al. . microbial production of , -butanediol by a surfac- tant (serrawettin)-deficient mutant of serratia marcescens h . j. ind. mi- crobiol. biotechnol. : – . genome announcement jb.asm.org journal of bacteriology o n a p ril , a t c a r n e g ie m e l l o n u n iv l ib r h ttp ://jb .a sm .o rg / d o w n lo a d e d fro m http://jb.asm.org http://jb.asm.org/ 호표지 ⓒcopyright korea institute of ecological architecture and environment . introduction . . background and purpose of study nowadays, buildings are responsible for % of electricity consumption, co emissions and waste generation [ ]. many studies and design philosophies regarding decrease in energy consumption in buildings have been done. the foremost design philosophies, that are being followed nowadays like sustainable design and green building design, all focus on lowering energy consumption in buildings using passive design. passive design makes use of the surrounding resources to provide a comfortable environment inside the building. pacheco et el. performed a study on energy-efficient design methods that can be applied to the building to lower energy consumption in the building [ ]. the study provides an overview of design criteria that can reduce the energy demand in residential buildings. tuohy et al. investigated the significance of thermal mass, insulation and ventilation for space heating energy use in sustainable housing [ ]. vincent and john carried out a study on the relation between building materials, building technology and their impact on energy requirement, environment and building occupant [ ]. kumar and suman studied the effect of passive pissn - x, eissn - http://dx.doi.org/ . /kieae. . . . design techniques like solar shading and building insulation on the decrease in the indoor temperature in three different areas through numerical calculations [ ]. in case of nepal, with energy consumption per capita of . kg, nepal is ranked th out of countries in the world in and is ranked out of countries for co emissions at . metric tons per capita in [ ]. the main source of energy in nepal is firewood and mostly is used for domestic heating and cooking but main source of energy for cooling is electricity [ ]. so, it is not about decreasing energy consumption but increasing efficiency use and not letting the consumption to increase unnecessarily [ ]. there are a few studies done regarding building energy consumption and comfort in nepal. toffin collected documentation on various vernacular buildings in nepal and showed how they created comfortable living spaces using local materials and space planning [ ]. bodach et al. studied the climate responsive features in various vernacular buildings in different parts of nepal [ ]. it is a very comprehensive study on passive designs of vernacular building based on both literature and field study. upadhyaya et al, did a study on the climate responsive features of the vernacular buildings in kathmandu valley and suggested some design guidelines for construction in kathmandu valley based on bioclimatic chart, building bioclimatic chart and mahoney tables analysis of kathmandu climate [ ]. rijal et al. carried out a series kieae journal, vol. , no. , feb. , pp. - kieae journal korea institute of ecological architecture and environment ) a study on passive cooling strategies for buildings in hot humid region of nepal manandhar, rashmi*⋅yoon, jongho** * dept. of architectural engineering, hanbat national univ., south korea ( rashmi@gmail.com) ** corresponding author, dept. of architectural engineering,hanbat national univ. south korea (jhyoon@hanbat.ac.kr) a b s t r a c t k e y w o r d increase in energy consumption in building is a big concern world over. in nepal, energy crisis is a big issue but energy demand in buildings is barely even thought about. in the southern part of nepal, where the weather is mostly hot during the year, cooling in buildings is very important. this is an initial study regarding building design strategies which focuses on cooling energy consumption in the building. it can be seen from the study that simple passive strategies can be applied in building design which can support in decreasing cooling load. different passive cooling strategies like orientation, building size, thermal mass, window design and two direct cooling strategies have been investigated in this study. direct cooling strategies like shading and natural cooling helps in passive cooling. different desing strategies have different impact on the cooling energy requirement and the study shows that thermo physical property of building materials has the maximum effect on the energy consumption of the building. each design strategy creates and average of % decrease in energy consumption, whereas the thermal conductivity can have as much as times more effect on the energy consumption than other design strategies. ⓒ kieae journal passive design strategy passive cooling design hot humid region nepal a c c e p ta n c e in f o received may , final revision received june , accepted june , a study on passive cooling strategies for buildings in hot humid region of nepal kieae journal, vol. , no. , feb. of empirical studies on the comfort of different vernacular houses in different parts of nepal [ - ]. his studies show how the vernacular buildings create heating and cooling for a comfortable living space in different climate zones of nepal. due to the energy crisis in nepal, it is better to have designs which can be independent of mechanical intervention for comfort. so, this study focuses on building design strategies based on passive cooling design for hot and humid region of nepal. . . methodology a research project was conducted in biratnagar, nepal to study how the low cost housing construction technology can be improved that was being promoted by habitat for humanity nepal [ , ]. the focus was on improving the comfort level inside the houses by decreasing the indoor temperature by manipulating the building materials. three houses were built during this study. one of the houses was used for calibrating the base case model for this study. the house used for calibration is m with two rooms. the floor is made of poured concrete over compacted stone, the walls are made of sundried mud bricks with mm air gap between two mm brick leaves and the roof is made of gauge corrugated tin sheets with mm straw on bamboo rafters. three hourly temperature and humidity data was taken of the outside temperature and the inside of the house. the simulation model was calibrated using the measured temperature so that the error was . %. biratnagar lies in the south east part of nepal at . n latitude and . e longitude. <fig. > shows the average monthly temperatures from march to october lie over °c and can go over °c during april to june, all year round the temperature stays well over °c and the relative humidity is lowest in april at over %, just when the temperature starts increasing, from february to may it remains below % and over it the rest of the year. this makes the climate very humid and hot. <fig. > shows the sky remains clear for most of the year except for the rainy season in the months of june to august and receives high solar radiation, an average of . wh/m /day. <fig. > shows the heating and cooling degree days for biratnagar and clearly shows the requirement of cooling during most of the year. . simulation . . simulation software energyplus v . has been used for the simulation study. it is a whole building energy simulation developed by us-doe with its roots in blast and doe- [ ]. it is an energy analysis and thermal load simulation program. jeplus, an independent gui for fig. . heating and cooling degree days in biratnagar fig. . base model configuration for studyfig. . monthly temperature and relative humidity in biratnagar fig. . monthly solar radiation and sky cover in biratnagar manandhar, rashmi⋅yoon, jongho ⓒcopyright korea institute of ecological architecture and environment parametric simulations for energyplus [ ], was additionally used for the various parametric studies. the minimum width for a living space should be ft. or m. as described by nepal building code [ ], so to simplify the model, the base model used for the study is m× m× m as seen in <fig. >. . . simulation overview the weather data of biratnagar, nepal used for simulation was obtained from meteonorm program. on energyplus official website, it is recommended that meteonorm weather data can be used if it is not provided by energyplus. during the experiment, the house was unoccupied, so for this study also no internal gains have been used. the thermal load profiles were calculated using “zonehvac:idealloadsairsystem”, which models an ideal hvac system that supplies cooling and heating air to satisfy zone heating or cooling load [ ]. the heating set point used is °c and cooling set point is °c. . passive cooling design strategies for biratnagar passive design is defined as the use of architecture and climate to provide heating, cooling, ventilation and lighting [ ]. it is a design strategy that does not require any active system inputs or the addition of conventional energy to operate. the key aspects of passive design are appropriate solar orientation, use of thermal mass and window placement. the strategies for passive cooling, aim to reduce or prevent heat gains into the building and encourage removal of excess heat from the building. this depends on two conditions: availability of heat sink and promotion of heat transfer towards the heat sink. passive cooling can be achieved through direct heat loss, indirect heat loss and isolated heat loss. direct heat loss can be achieved by obstructing solar gain by use of large roof overhangs, window shading devices and even site vegetation and by using natural ventilation. cross ventilation is the easiest to do by placing openings facing each other and using natural breezes to cool the inside space. indirect loss can be achieved by using material such as water and earth to absorb extra heat and lose it to the surrounding; roof pond, earth berming and trombe walls are good examples. isolated loss is achieved when the heat exchange mechanism is separated from the space needed to be cooled. earth tunnel is a very good example. for this study, key passive design strategies and direct cooling designs have been studied. . . building design - orientation and size using the base model and increasing the length of model by ratios : . , : . and : , represented by models by , by . , by . and by respectively, the best orientation for building is analyzed for minimum heating and cooling load. <fig. > shows the cooling energy for windowless models. for the cubic model, there is no difference when the model is oriented to cardinal directions, but as the size of the model increases and the long face of model is oriented to either south or north, the cooling energy decreases. but in case when the orientation is decided by using window on the longer side of the building, large change in energy demand can be observed as shown by <fig. >. both instances show that when the building is oriented towards n-s, the energy requirement is lower. <fig. > shows that for models with windows, there is not so much change in cooling energy and is lowest when the window is facing north, which may be because in this position heat is lost through the window instead of heat gain. as the nepal building code [ ] allows for a building ratio of : , two more models are added to study effect of building size on energy requirement, represented by by . model ( : . ) and by model ( : ). <fig. > shows that when the volume of the model increases, by increasing the length, cooling energy decreases. there is % decrease in cooling energy for each successive increase in length whereas a change in volume by increase in the fig. . cooling energy requirement for windowless models in different orientation fig. . cooling energy requirement for models with window in different orientation a study on passive cooling strategies for buildings in hot humid region of nepal kieae journal, vol. , no. , feb. slope of the roof tends to increase cooling energy by %. <fig. > shows change in energy requirement when the aspect ratio of building changes. upto the ratio of , the heating energy increases and the cooling energy decreases, decreasing the total energy requirement. from : to : . , heating energy decreases by . % and cooling energy and total energy requirement increases by only . and . % respectively. but again when the ratio increases to : , the heating energy increases and both cooling and total energy decreases. <fig. > shows the increase in energy requirement when the roof slope increases by ˚ successively. instead of using all the models from fig. , only the model type (aspect ratio of : . ) as representative model. at first the increase is very small, but as the slope increases, energy requirement increases at a higher rate. upto ˚ (type -b), the increase is quite low, only about % increase in cooling energy but at ˚ (type -d), this change is very high. . . thermal mass design the living standard survey of nepal has identified basically three types of construction for outer wall, which are mud bonded bricks/stones, cement bonded bricks/stones and wood and tree branches [ ]. in case of roofing materials, % of the household live in buildings with tile or slate roof, % live in galvanized corrugated tin sheet house and % live in concrete roof houses [ ]. as stone is not a common building material in biratnagar, it has not been considered for this study. <table > and <table > show the thermal property (u-values) and tentative cost per square meter in nepali currency which is rupee (npr) for different building materials combination. simulation name roof materials (starting with outside layer) u-value (w/m k) cost per m (npr) base_roof gauge cgi+ mm thatch . roof mm concrete . roof mud tiles+ mm concrete . roof mud tiles . roof gauge cgi . roof gauge cgi+ mm plywood . roof mud tiles + mm concrete+ mm polystyrene . roof mm concrete + mm polystyrene . table . roof construction materials used for study fig. . cooling energy requirement comparison for varied size and roof slope models fig. change in cooling energy requirement for different building materials combinations fig. . change in energy requirement due to change in length of building fig. . change in energy requirement due to change in roof slope manandhar, rashmi⋅yoon, jongho ⓒcopyright korea institute of ecological architecture and environment <fig. > shows that the lowest energy requirement might not come from the combination of envelopes with lowest u-values. in <fig. > the u-values in w/m k are shown in the first row for the roof combinations and for the walls are shown in the first column. the names in the second row and column corresponds to table and respectively. the numbers with blue bars represents the cooling energy requirement in kwh/m . for the lowest cooling energy requirement of . kwh/m ( . % decrease), the best combination is wall made of mm mudbrick and polyurethane insulation, layerwall , ( % decrease in u-value) and roof made of thatch and cgi, base_roof. and comparing cost of layerwall to cost of base case wall, increase in cost is only . %. . . window design windows affect both solar gain and natural ventilation. the glazing type and area affects the amount of solar radiation entering the space and the shading devices helps to control this. windows being transparent are the only means through which solar radiation can enter into the building and can hence provide solar heating in the building. thus, windows can cause the cooling energy to increase if there is uncontrolled solar gain from large windows. shading devices are thus very important to control solar gain through transparent apertures on the building envelope. <fig. > also shows the effect of window orientation on energy requirement. compared to <fig. >, when there is window, the energy requirement varies significantly. to decrease cooling energy, a northern window is better. <fig. > shows the change in energy requirement as the size of window increases along with type of window glazing. a triple glazed window requires the same amount of cooling energy as a window with double glazed window when the size of window is % smaller. fig. . change in cooling energy due to change in size and glazing of window . . shading shading is a very effective way for decreasing solar heat gain both from the windows and wall. shading devices are designed to obstruct solar gain in summer and let winter sun enter into the space. it can also function as a dual device to direct prevailing winds into the space. the summer solar altitude angle is at an average ° in biratnagar. since the models used for the study here is only m, using simple geometry, it can be seen that an overhang of about . mm can provide summer shade for total wall as shown by <fig. >. simulation name roof materials (starting with outside layer) u-value (w/m k) cost per m (npr) base_wall mm mud brick inside and outside with mm air cavity . masswall mm kiln brick with mm cement plaster inside and outside . masswall mm kiln brick with mm cement plaster inside and outside . masswall mm kiln brick with mm cement plaster inside and outside . masswall mm kiln brick with mm cement plaster inside and outside . masswall mm mud brick with mm mud plaster inside and outside . masswall mm mud brick with mm mud plaster inside and outside . masswall mm mud brick with mm mud plaster inside and outsidee . masswall mm mud brick with mm mud plaster inside and outside . cavitywall mm mud brick+ mm air cavity+ mm mud brick with mm mud plaster in/out . cavitywall mm mud brick+ mm air cavity+ mm mud brick with mm mud plaster in/out . cavitywall mm mud brick+ mm air cavity+ mm mud brick with mm mud plaster in/out . cavitywall mm kiln brick+ mm air cavity+ mm kiln brick with mm cement plaster in/out . cavitywall mm kiln brick+ mm air cavity+ mm kiln brick with mm cement plaster in/out . cavitywall mm kiln brick+ mm air cavity+ mm kiln brick with mm cement plaster in/out . cavitywall mm kiln brick+ mm air cavity+ mm kiln brick with mm cement plaster in/out . layerwall mm mud plaster+ mm mud brick+ mm insulation . layerwall mm mud plaster+ mm mud brick+ mm insulation . layerwall mm mud plaster+ mm mud brick+ mm insulation . layerwall mm mud plaster+ mm mud brick+ mm insulation . layerwall mm cement plaster+ mm kiln brick+ mm insulation . layerwall mm cement plaster+ mm kiln brick+ mm insulation . layerwall mm cement plaster+ mm kiln brick+ mm insulation . layerwall mm cement plaster+ mm kiln brick+ mm insulation . table . wall construction materials used for study a study on passive cooling strategies for buildings in hot humid region of nepal kieae journal, vol. , no. , feb. it can be seen from <fig. > that as the width of the shade increases, the cooling energy decreases, meaning as the width of the shade increases, not only the peak summer sun but more solar gain is blocked over the course of the year. this decreases the solar gain for longer periods and decreases the cooling energy requirement. this also means that the roof overhang cannot be determined by the maximum solar altitude which occurs during jun -jul which is °, as the solar altitude can range from - ° during summer periods. using simple geometry shows that a mm overhang can shade for solar altitudes upto °, also mm overhang can shade for solar altitude angle of ° and mm for °. a mm horizontal shade will be able to shade solar altitude of ° only. . . natural ventilation the second direct cooling technique studied here is natural ventilation. it is where natural air breezes can be used for cooling the space in summer. <fig. (a)> shows the annual wind direction and speed for biratnagar. we can see that southerly wind is prevalent, so window position can be kept on the south so that it is easy for sun control as well. upto km/hr wind prevalent in biratnagar is mostly concentrated on the south direction but <fig (b)> shows that the temperature of air coming from this direction is about °c. cooler wind of °c is concentrated to mostly west and north-west direction. but since the summer outside temperature rises upto °c, the air temperature on the south will still be able to cool the environment as it is lower than the ambient temperature. <fig. > shows the inside temperature due to natural ventilation. compared to an unshaded window, a shaded window performs much better. for an unshaded window, opening the window simply means bringing the air at outside temperature to inside, which simply manages to bring the inside temperature near to outside temperature. so, for natural ventilation to work, a shade or means to cool down the outside air before entering into the fig. . (a) annual wind direction and speed (left) (b) temperature of wind (right) in biratnagar fig. . change in internal temperature due to natural ventilation fig. . heating and cooling energy change due to change in infiltration fig. . change in cooling energy due to change in projection of roof overhang fig. . roof overhang for summer solar shading manandhar, rashmi⋅yoon, jongho ⓒcopyright korea institute of ecological architecture and environment space, is imperative. unwanted ventilation is called infiltration and due to the construction methodology in nepal, it is very high, which was seen during the calibration of the project model. the infiltration rate calculated for calibrated model is ach. although small increments in infiltration has little effect, like from . to . ach, large change in infiltration can have a significant impact as can be seen from <fig. >. it can also have an impact on the natural ventilation which is mainly achieved by opening the window, that is to say by controlling when the air can move in and out of the spaces. as ventilation works better with opposite facing windows, <fig. > shows the cooling energy requirement for different window positions at and ach. since the building orientation is n-s, it is also better to have windows on the north and south walls as well. <fig. > shows that the lowest heating energy occurs when window is on north and south position. . conclusion different building design strategies have different effect on the heating and cooling energy requirements. as shown by heating degree days, the heating energy requirement in biratnagar is very low as compared to the cooling energy requirement. the cooling energy requirement is sixteen times more than the heating energy requirement in the base case model. the increase in cooling energy due to worst orientation as compared to best orientation is an average of % over different model size. the maximum change in cooling energy requirement due to change in length of the building is % and due to slope is %. for building materials, as compared to best case scenario, the worst case scenario can increase the cooling energy by % when the cost of construction for worst case scenario is still % more expensive than best case scenario. the window can cause % change in cooling energy by changing its size. cooling energy decreases about . % on average due to presence of shading. improvement in construction technology to provide a more air-tight building envelope can decrease the cooling energy by %. so, it can be seen from this study that the thermal conductivity (u-value) of the building envelope has more significant effect on the cooling energy than other design strategies. as such, energy consumption has not become a big concern in nepal but the present scenario of increasing construction activity with change in life style and decreasing energy sources calls for more energy conscious designs. by incorporating these design concerns in building design, nepal can get a head start on decreasing energy consumption in buildings. references [ ] kitio, v. ( ) resource efficient built environment: methodologies and lesson learned. talk program titled “green building design”, kathmandu nepal. (http://unhabitat.org.np/?post_type=publications&p= , accessed dec, ) [ ] pacheco, r., ordonez, j. and martinez, g. ( ) energy efficient design of building: a review. renewable and sustainable energy reviews, ( ), - . [ ] tuohy, p., mcelroy, l. and johnstone, c. ( ) thermal mass, insulation and ventilation in sustainable housing – an investigation across climate and occupancy. proceedings of the th international ibpsa conference on building simulation, montreal, canada. [ ] vincent, a. and john, g.r. ( ) effects of rationalization of active and passive techniques in the building industry. plea – the st conference on passive and low energy architecture, eindhoven, the netherlands, - . [ ] kumar, a., suman, b.m. 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[ ] jeplus website: http://www.jeplus.org/wiki/doku.php?id=start (accessed dec ) [ ] dudbc nepal (http://dudbc.gov.np/,accessed aug, ) [ ] passive solar design (accessed may: http://passivesolar.sustainablesources.com/) nphys langford.indd futures nature physics | vol | june | www.nature.com/naturephysics warez annotated audio transcript only. “we weren’t listening on the right channels. th at was the old seti in-joke. we should be listening to the media we haven’t invented yet.” “and now we have?” “well… not as such, minister. th e artefact is millennia old and spent about a century in the british museum egyptology collection, labelled ‘ritual object — purpose unknown’. one day it got used in a round of dating calibrations, and slow neutron imaging showed an internal structure that wasn’t at all old kingdom. th e science-fi ction fans in our technical team call it an ansible.” [gesture] “which would be an anagram of… of…” “i have not researched that aspect. what it is, though, is a galactic modem. an interstellar access point. we’ve identifi ed thousands of stations, nodes, channels, whatever. a fi re- hose blast of information.” [gesture] “but surely all in a ghastly foreign lingo?” “up to a point, minister. some communications are sheer library of babel — or babble. many, though, seem designed for transparency. th ey begin with helpful language lessons, visual teaching aids.” [explanatory gestures] “nasty tic you have there. so, exercise one goes: ‘take me to your leader?’” “a little more sophisticated than that, sir. so much more so, indeed, that there are built-in pitfalls.” “one has heard rumours.” “our interface soft ware is now blocking channels # and # , which produce undesirable symptoms in most people exposed to the message content. convulsions, death, that kind of thing. also # , , whose researcher came through in good health but with her former language skills overwritten. apparently she now thinks in fl uent vegan or arcturan and is fi nding it hard to relearn english. in fact…” [several agitated gestures] “interesting, but can we be more focused? less pantomime and more valuable scientifi c insights that will advance the frontiers of knowledge and turn a whacking profi t.” “well, # is quite intriguing. it claims to off er the secrets of cheap interstellar travel. some kind of light-pressure drive that relies on destabilizing the local sun.” “th at is, our local sun?” “in eff ect, yes.” [gestures] “good lord. better not tell nasa about that… something more practical, please.” “th e payload of # is allegedly a total-spectrum antibiotic. we didn’t care to investigate too closely, but this would seem to be a replicating catalyst that persists in the environment and is incompatible with carbon-based life. one of those sf fans in our crew thought the target users might be silicon intelligences.” [gestures] “caveat emptor. onward!” [gesture] “just for balance, # promises the same for semiconductors. no computer viruses, because no surviving computers: the catalysts roll us back to ohm’s law technology… now # , has a certain fascination. all-purpose solution to any energy crisis.” [gestures] “th ere will, i presume, be a catch.” “th e summary claims that it’s a simple technique of reprogramming the space-time attributes of matter to generate antimatter in arbitrary quantities. % conversion effi ciency and zero co footprint.” “th e boffi ns already make that stuff , don’t they? at cern and suchlike places.” [gesture] “exceedingly tiny amounts, minister, at a rate of billions of years per gram. we are off ered the opportunity to make antimatter by the kilogram, with a total energy release of circa megatonnes when that mass encounters normal matter and annihilates. just as easy to make a tonne for a yield of around , megatonnes. and it’s supposed to be simple.” [gestures] “one detects a pattern. dangerous toys.” “yes, minister. we decided not to unpack full details, just in case it really is simple, but i lost no time putting a block on that channel too. th e # , message header, by the way, includes a slogan that seems to translate as ‘make energy fast!’” “likewise, no doubt, ‘information wants to be free.’ pray continue your most interesting narrative.” [gestures] “of course we don’t know that the actual contents will match the instructions on, as it were, the tin. it may be signifi cant that many of these communications take the general form of # , which off ers immunization against invasive memes, which are allegedly liable to reconfi gure one’s entire culture as an ansible broadcasting bot that exists only to relay the original memetic message.” “th at, at least, sounds useful … ah, maybe not. one has heard of trojan horses. th e benefi ts of a classical education.” [gestures] “yes, minister. i should have mentioned that our girl who lost her english managed to infect three other people with whatever she’s now speaking, before we isolated everyone concerned… [gestures] th ere’s a wide range of suspected trojan channels, mostly rather less ingenious than # . to paraphrase a typical specimen: ‘greatly enlarge your species potential!’” “or conversely, ‘th ere’s one born every minute’.” “th e fi nal disappointment, i’m afraid, is that we don’t seem to be detecting any real-time communication out there. just endlessly repeated broadcasts, most likely from zombie networks. [numerous gestures] maybe it would have been diff erent if we’d accessed the galactic net thousands of years ago, back when some ufo tourist presumably overfl ew the old kingdom and dropped his mobile phone.” “you fear the original broadcasters are all gone?” [gestures] “i am trying my best to be optimistic. in fact i’m working hard to convince myself that although the ansible network may be choked with this junk, a genuine extraterrestrial contact is still possible.” [gestures] “you mean…[multiple gestures] go on: i’m beginning to understand.” “yes, minister. we need to learn the trick of listening with another technology that we haven’t invented yet.” [multiple complex gestures] note: exchange continues solely in non- standard sign language. both subjects now segregated as carriers of contagious memetic dactylology tentatively associated with channel # . prognosis uncertain. david langford based in reading, uk, david langford is a freelance author, critic and computer consultant. he has won hugo awards. excitement is infectious. ja c ey 	warez sus- - -eo-ver -oliphant_ p .. case report—michigan sustainability cases biofuels: beneficial or bad? should a ghanaian chief sell his land for biofuel crop cultivation? elizabeth oliphant, mark finlay, adam c. simon, , and brian k. arbic background michigan sustainability cases (msc) is an initiative funded by the uni- versity of michigan’s transforming learning in the third century ini- tiative and the school for environ- ment & sustainability (seas) that is creating case studies for sustain- ability education. msc is writing and piloting initial cases throughout the u-m campus from its current home in seas. for over years, seas professors have successfully taught with case-based learning in their classrooms, which has proved more effective than lectures. msc is reimagining this technique, while drawing from decades of in-house experience. msc also refers to the individual case products generated by the ini- tiative. mscsare modular multimedia sustainability case studies developed through partnerships with practi- tioners, teachers, and students. mscs present actual experiences or expe- riences inspired by real circum- stances of key “decision makers” through a digital platform. like the traditional case method, mscs present students with a case, a deci- sion maker, and various stakehold- ers, allowing students to analyze priorities and tradeoffs in reaching a recommendation. unlike the tra- ditional case method, each msc is accompanied by multimedia edge- notes, a podcast, and an interactive learning exercise. together, these bring greater depth to the case, pro- ducing more engaged, participa- tory learning. mscs impart critical interdisciplinary competencies, for stronger sustainability leaders of the future. introduction biofuels have been touted as one promising solution for reducing carbon dioxide (co ) emissions worldwide. these products take many forms, but all share an origin in plants grown and processed specifi- cally to meet energy needs. because plants absorb co and convert it to organic matter as they grow, the as- sumption has followed that when biofuel plants are burned, net co emissions should be zero. however, as biofuels have made their way into the world’s energy mix, questions have arisen not only about the actual environmental impacts, but social and economic impacts as well. amid this backdrop, this case focuses on biofuels as a potential partial so- lution to the energy crisis in ghana. for years, ghana’s industrial devel- opment and economic growth have been slowed by energy shortages. despite these energy concerns, ghana still has a goal of universal access to energy and use of renewable energy sources for percent of all electricity by . biofuels are one potential way for ghana to meet this goal, and this case focuses on the sale of land for growing a biofuel crop. the two primary stakeholders chief ofori and naloil are fictional char- acters, but they are based on real life actors. naloil wishes to grow ja- tropha curcas, a shrub with high oil content in its seeds that can be used to produce biofuel. growing this crop will have economic, social, and environmental impacts on chief ofori’s community and land, which must be considered when making his decision. in many regions of ghana, especially in more rural ar- eas, traditional leaders maintain sole authority to make land use deci- sions, including selling their land. for chief ofori, the decision about the future of his people and his land is his alone. this case study is designed to be supplemental material for classes earth and environmental sciences, program in the environment, university of michigan, ann arbor, michigan. sustainability mary ann liebert, inc. • vol. no. • february • doi: . /sus. . .eo d ow nl oa de d by u ni ve rs it y of m ic hi ga n e- jo ur na l pa ck ag e fr om w w w .l ie be rt pu b. co m a t / / . f or p er so na l us e on ly . that explore energy consumption, land use development, or the global supply chain. students will gain a better understanding of stakeholder considerations and the complexity of sustainability issues. many countries aim to reduce their carbon footprint, but the route to do that is not clear. this case study highlights the tension created by biofuels, which offer eco- nomic opportunities for locals, but have the potential for negative effects on the people, economy, and envi- ronment. throughout this case, students per- form quantitative and qualitative assessments of the effects of growing this biofuel crop. in the engaged learning activity, students calculate the water consumption required by jatropha curcas plants. in the written case, students must consider the ef- fects this decision will have on local school quality and individual land owners. students will weigh different stakeholder opinions and the effects of selling land for jatropha curcas cultivation before coming to a con- clusion about what they would do if they were in chief ofori’s position. through this case, students will be exposed to stakeholder analysis as well as elements of ghanaian culture such as fufu, a traditional soup. this case study focuses on the ghanaian biofuel crop jatropha curcas, but biofuels are a universal issue. by be- ing able to analyze sustainability is- sues from abroad, students will be better equipped to answer sustain- ability questions at home. the story blackout the lights flickered throughout the room, and then darkness. no one knew when the lights would come back on. it could be five minutes, or it could be a whole day, but until then the residents of accra, ghana, would live in darkness or have to rely on expensive backup generators. this was the reality of the energy crisis in ghana: rolling blackouts lasting anywhere from hours to days, lack of universal electricity access, and a national economy hindered by a shortage of power that was having consequences for urban and rural residents alike. miles away from accra, in the agogo traditional area of ghana, a local chief confronted the energy crisis in his community. it was somewhat cool and awfully humid in the early light of day. sitting back in his chair, hands folded on his lap, chief ofori stared out the window as the sun climbed over the horizon. his relaxed posture belied internal turmoil as he labored over a decision that could mark a new era for his people: should he sell his land to the norwegian company naloil for the cultivation of jatropha curcas, a biofuel crop? an expected knock on the door prompted a hasty retreat from his ruminations, and he beckoned his guests inside. two men entered. his first impression was that their pro- fessional attire was not really suited to the warm weather, but they were putting on an admirable perfor- mance in not betraying discomfort. he stood to greet them from behind his desk, and they both came forward and took their turns in shaking his hand before they all proceeded to sit. the man to his left, who had blonde hair and appeared to be in his forties, began speaking. “so, chief ofori, i expect you have made your decision?” he spoke with a thick norwegian accent, but slowly and in a manner that suggested that he believed the chief’s english to be poor. “naloil is convinced that it has made you an offer that you can’t refuse.” he chuckled to himself, probably convinced that the chief had not caught the reference to the godfather. but he had. the other man, who appeared to be much older, gave his partner a scolding look, sighed under his breath, and leaned across the table to bring his face closer to the chief’s. “look, let’s just finish with this business,” he said, speaking at a faster pace than his colleague. he leaned back again to reach for his suitcase on the floor and pulled out several sheets of paper, all of which had two lines for signatures at the bottom. one line on each page had already been signed. “if you would kindly sign these forms, we can finalize this land sale. we believe we have given you an ample amount of time to come to a decision.” he pushed the papers toward the chief, who slowly looked them over despite being very familiar with the text— , acres, about one-sixth of his land, were literally on the table. the chief had thought that he was prepared to settle the matter, but at this crucial moment, with the deci- sion requiring only his signature on those contracts, he hesitated. was he making a grave mistake in selling this much land for the cultivation of ja- tropha curcas, a biofuel crop he had never even heard of before this offer was presented to him? despite having convinced himself that exchanging the land for increased development opportunities and economic activity was the right choice, he could not shake his lingering doubts. drawing on all his will to assert an outward appearance of calm, chief mary ann liebert, inc. • vol. no. • february • doi: . /sus. . .eo sustainability biofuels: beneficial or bad? d ow nl oa de d by u ni ve rs it y of m ic hi ga n e- jo ur na l pa ck ag e fr om w w w .l ie be rt pu b. co m a t / / . f or p er so na l us e on ly . ofori resolutely pushed the papers back toward the men. “gentlemen, i sincerely apologize, but i need some more time. i will get back to you with my decision to- morrow.” he mustered a smile as the men glanced at one another, clearly displeased. however, they quickly changed their expressions and nod- ded amicably at the chief. after brief farewells, the men headed toward the door, the older man hollering over his shoulder that they would be back first thing in the morning. kwadwo ampah ofori was the par- amount chief of the agogo tradi- tional area in ashanti, a land of over , people, and he had to decide their future. the energy crisis in ghana the energy crisis in ghana began in and only worsened due to erratic gas supplies from foreign countries, intermittent rainfall that had made hydropower less reliable, and rising energy demand. in , ghana had a total installed power ca- pacity of , mw, but average available energy hovered around , mw, as most power plants did not operate consistently at full capacity. however, with the total energy de- mand over , mw, even if these plants always ran at full capacity, they stillwouldnotbeabletomeetdemand. ghana has several major hydropower plants, including akosombo, bui, and kpong, that produce a signifi- cant portion of its electricity. hy- dropower dams depend on having a sufficiently high water level behind the dam to run. if water levels drop too low, the turbines in a hydroplant can be damaged or become unable to produce energy. due to irregular and sparse rainfall in ghana, some of these plants are now at risk of shut- ting down. akosombo, the largest hydropower plant in ghana, oper- ated at a water level of feet—an all-time high—in . however, in december , the water level dropped to feet, dangerously near the -foot threshold that would force a total shutdown. one more year of drought could push these plants past the tipping point. ghana also relies heavily on both domestic and imported oil and gas for energy production. in , ghana began producing oil following the discovery of oil in the ju- bilee oil field, located about kilo- meters off the ashantiland peninsula in western ghana. by , ghana was producing over , barrels of oil per day, mostly from this field, with . million metric tons of crude oil exported in . while the oil field has the capacity to produce much more oil, this effort was constrained by the fact that ghana has only one petroleum refinery plant. in , this refinery produced , metric tons of pe- troleum products, but ghana im- ported . million metric tons, mostly from neighboring nigeria. this meant that ghana was heavily dependent on nigerian oil and gas, but that supply has been subject to disruption. in , there was a percent reduction in the imported volume of gas supplied to thermal electric plants from nigeria through the west african pipeline project. this reduction was attributed mostly to debt accumulated by the ghanaian government and attacks on pipelines and facilities by a militant group calling themselves the niger delta avengers. even with this reduction, however, a hefty percent of ghana’s natural gas in was imported from nigeria, compared to the percent that was produced domestically. then, in june , nigeria cut off ghana’s natural gas supply entirely, due to ghana’s ac- cumulated debt and nigeria’s need to use the fuel within their country. because of these supply issues, the government expressed firm desires to reduce its dependence on im- ported oil and gas, as well as for location of the jubilee oil field, located about kilometers off the ashantiland peninsula in western ghana sustainability mary ann liebert, inc. • vol. no. • february • doi: . /sus. . .eo oliphant et al. d ow nl oa de d by u ni ve rs it y of m ic hi ga n e- jo ur na l pa ck ag e fr om w w w .l ie be rt pu b. co m a t / / . f or p er so na l us e on ly . ghana to eventually become a pro- minent international exporter of oil, gas, and electricity. this would happen, however, only if ghana could overcome the limited pro- ductivity of its domestic plants and oil fields. the energy crisis had countrywide economic effects, with the gdp growth rate slowing from . percent in to . percent in . un- derscoring these effects, the minister of energy and petroleum, emmanuel armah-kofi buah, stated that elec- tricity supply and its shortfalls were the “nerve center of our economy, the critical constraint to our economy’s growth.” to address this issue head- on, ghana set ambitious goals for the year , including universal access to electricity, , mw of gener- ation capacity, access to liquid pe- troleum gas for percent of the population, and the generation of percent of domestic electricity from renewable sources. grid expansion projects were already underway, and by early the sankofa gas pro- ject, which would generate , mw of clean power, was expected to be completed. in , ghana was generating only . percent of domestic energy from renewables, so reaching the per- cent goal would be a challenge. but the country had invested $ mil- lion into the scaling up renewable energy plan (srep). this plan in- vested in four project areas: renewable energy mini-grids and stand-alone solar photovoltaic systems, solar photovoltaic-based net metering with storage, utility-scale solar/wind power generation,andtechnicalassistance.in addition, foreign investors saw ghana as a prime location for the cultivation of biofuel crops, and since have been pushing for biofuel production as a way to increase the availability of renewable fuels and reduce ghana’s reliance on foreign oil. three main types of biofuel cultiva- tion projects operating at different scales were developed in ghana over the past couple of decades. one was cultivation by small-scale farmers, or out-growers, who were linked to commercial biofuel production or processing. another was large in- dustrial farms (about acres or larger) that cultivated and produced biofuel for local consumption. the third—which pertained to naloil and its proposition—was large in- dustrial farms for national and in- ternational consumption. if chief ofori sold his land for biofuel crop cultivation, would it provide new opportunities for his people, or would he be sealing their fate by sacrificing a significant amount of productive land to a foolish venture? an overview of diesel after a filling lunch of fufu in nka- tekwan (peanut soup), chief ofori returned to his desk to pore over, for the final time, the months of research he had naively convinced himself would practically make his decision for him. before starting his research, he had possessed only the faintest notion of the difference between conventional fuels and biofuels and had not been especially knowledge- able about the pros and cons of cul- tivating biofuel-producing crops. his starting point had been educat- ing himself about diesel and biodie- sel. diesel is used for car, aircraft, truck, and railroad fuel. in the united states in , it made up percent of petroleum fuel consumption in the transportation sector, and worldwide its consumption was actually higher than that of gasoline. in ghana, diesel generators had become com- mon due to the ongoing power cri- sis. many companies had to rely on these generators to stay open and productive during long electricity shortages. learning this had made him consider the potential for his people to use some of the biodiesel produced from jatropha curcas to fuel their own generators. more re- liable access to power and electricity would greatly improve the quality of life for many of his people. although both diesel and gasoline are derived from petroleum, they have different properties and serve different purposes. when crude oil is distilled, it separates into heavier and lighter components. gasoline and jet fuel are two examples of lighter dis- tillates, while diesel and fuel oil are on the intermediate-to-heavy side. diesel’s higher density explains why it contains to percent more energy per gallon than regular gaso- line. however, its low volatility means a gas engine cannot not run on diesel. in a typical gas engine, fuel is mixed with air before being com- pressed and ignited by a spark. in a diesel engine, the air is compressed distilling crude oil yields multiple oil products of varying densities mary ann liebert, inc. • vol. no. • february • doi: . /sus. . .eo sustainability biofuels: beneficial or bad? d ow nl oa de d by u ni ve rs it y of m ic hi ga n e- jo ur na l pa ck ag e fr om w w w .l ie be rt pu b. co m a t / / . f or p er so na l us e on ly . first, producing enough heat to ignite the fuel when it is added. alternative sources for a more sustainable future? chief ofori had also learned that biofuels are acquired from organic matter such as animal waste or plant matter. they are, in theory, carbon neutral due to the fact that plants take in carbon during photosynthesis, and this same carbon is returned to the atmosphere when fuels derived from these plants are burned. this is dif- ferent from traditional fossil fuels that have been buried beneath earth’s surface for millions of years. when burned, fossil fuels release carbon dioxide and other greenhouse gases into the atmosphere. the burning of fossil fuels has been a major contributor to global climate change over the last two centuries. oil is also a finite resource, and the earth’s current supply will be used up before it can be replenished. there- fore biofuels are more renewable on a human time scale. however, in reality biofuels are not completely carbon neutral due to the energy required to transport mate- rials and power the facilities used to produce biofuels from organic mat- ter. additionally, there are concerns about prioritizing land use for biofuel crop cultivation instead of food crops, and about the environmental impact biofuel crops could have. despite these concerns, biofuel is viewed by many as an efficient means of producing energy sustain- ably, and as a result, percent of the world’s total energy demand is being met using bioenergy. in , the strategic national energy policy of ghana called for percent of gas- oline consumption to be replaced with biofuels and for percent of kerosene to be replaced with jatropha curcas oil by . as a political figure in the area, chief ofori has a lot of influence, so if he supported and promoted the culti- vation of biofuels, others might be inspired to follow suit. if any of the biodiesel crops cultivated on his land were to be used domestically, it would aid in ghana’s effort to secure cheaper and more reliable domestic sources of energy. additionally, bio- fuel seems to be a growing market that could bring economic opportu- nities to his people. there are two types of biofuel: pri- mary and secondary. primary bio- fuel, such as firewood, charcoal, and animal dung, is unprocessed and used in its natural form. secondary biofuel involves processing. the two most common secondary biofuels are ethanol and biodiesel. ethanol is created from any raw material with a significant amount of starch or sugar that can be fermented and distilled, and is commonly mixed in with gas- oline to reduce air pollution. how- ever, concerns have been raised about possible negative environmental ef- fects of corn ethanol. biodiesel is primarily used for trucks and jet fuel, and comes from vegetable oil or ani- mal fat mixed with alcohol. some plants that produce oil that could be turned into biodiesel include palm, soybean, coconut, and jatropha cur- cas, which is the crop that naloil wants to grow on chief ofori’s land. ja-tro-wha.? chief ofori had never even heard of a jatropha curcas plant prior to naloil’s proposition. he learned that jatropha was a shrub or small tree farmed around the world. while there are around species of jatropha curcas, only one can be used to produce biodiesel. this species is jatropha curcas, used for its seed content of to percent oil. it is native to mexico and other parts of central america, but can grow in many tropical and subtropical a close-up look at the jatropha curcas plant sustainability mary ann liebert, inc. • vol. no. • february • doi: . /sus. . .eo oliphant et al. d ow nl oa de d by u ni ve rs it y of m ic hi ga n e- jo ur na l pa ck ag e fr om w w w .l ie be rt pu b. co m a t / / . f or p er so na l us e on ly . regions. when ofori discovered the geographical conditions necessary for its growth, he realized why agogo and the whole of rural ghana had been targeted so intensely by com- panies like naloil: the climate and altitude are ideal, the temperatures just right, and the rainfall patterns more than adequate. jatropha curcas was originally culti- vated to harvest its oil for soap. ad- ditionally, it was sometimes grown as a hedge for keeping animals out of farm plots due to its height and slight toxicity. jatropha curcas’s toxicity is negligible to humans, but it did keep insects away, which could reduce the need for pesticides. chief ofori had been very pleased to learn that jatropha curcas is not harvested for food. in his relatively poor community, hunger is wide- spread, and using food crops for fuel would surely inspire anger and back- lash. in fact, one of the reasons that this plant seems so desirable as a biofuel crop is that it does not have the po- tential to be used in competing ways. however,whileitisnotapotentialfood source, the plant would still compete with food crops for land and resources. another trait ofori found desirable is that the plant bears fruit after nine months. this is important because a jatropha curcas plantation could therefore make money within the first year. in wetter climates, moreover, harvesting could occur year-round, meaning plantation workers would have a continuous source of income. annually, individual plants on aver- age produce . kg of seeds, and kg of seeds are required to produce one liter of biodiesel. this means, on average, that one hectare of jatropha curcas yields about tons of biodie- sel. the process of extracting oil for biodiesel also results in byproducts such as seed cake that could be used for fertilizer or animal feed. chief ofori also learned as much as he could about the process of creat- ing biodiesel from jatropha curcas oil. to begin, oil can be extracted from jatropha seeds through a vari- ety of methods such as using solvents or manual pressing. this produces crude jatropha oil, which can then be processed through a transesterifica- tion reactor to create crude biodiesel. the jatropha curcas cultivation boom in ghana began in late due to rising oil prices and a con- current push by many nations to invest in cleaner energy sources. at that time, land owned by foreign investors for biofuel production re- presented percent of ghana’s farmland. though oil prices have since fallen, and oil was discovered in ghana in —leading to a sharp decline in the jatropha curcas market—many biofuel plantations still operated in ghana, and naloil was intent on adding agogo to this number. impacts on the land he called home chief ofori learned that there were also clear downsides to the cultiva- tion of jatropha curcas, with the most important and worrisome, from his perspective, being its high water consumption. his region would re- quire extensive irrigation to accom- modate jatropha curcas cultivation because its farms only used wells and shallow aquifers for water. one concern was that the water needed by a jatropha curcas plantation could otherwise be used by his people for growing their own food, drinking, or bathing. his region could support these water needs now, but with cli- mate change, water supply in the coming decades was uncertain. research from the university of twente in the netherlands con- cluded that jatropha curcas required five times as much water per unit of energy produced ( , liters of water per liter of biodiesel) as the common biofuel crops sugarcane and corn, and nearly ten times as much water per unit of energy pro- duced as sugar beets, which were the most water-efficient biofuel crop in use. chief ofori knew that one of the most serious issues facing ghana is irregular rainfall leading to low water levels at locations that produce hydropower, which in turn contrib- ute to the energy shortage. so using water for biofuel crop production, particularly for jatropha curcas, could place further strain on ghana’s water resources at a time when they were being increasingly stretched thin. another worrisome downside is that there are numerous examples of jatropha curcas operations that had negatively impacted surround- ing agriculture. jatropha curcas cul- tivation reduces the land available for other crops, forcing farmers to em- ploy shorter fallow periods to com- pensate for smaller plot sizes. fallow periods allow land to lie seedless for a time and are necessary to restore nutrients to the soil in between pe- riods of crop cultivation. following the loss of land to jatropha curcas operations, the number of farmers using fallow periods of less than one year had increased and the number of farmers using fallow periods of more than three years had decreased. this trend could lead to annually decreasing crop yields and eventually to land that no longer yielded suffi- cient crops for food needs. alternatively, to prevent the conver- sion of agricultural land to jatropha curcas plantations, jatropha curcas could be grown on degraded land. mary ann liebert, inc. • vol. no. • february • doi: . /sus. . .eo sustainability biofuels: beneficial or bad? d ow nl oa de d by u ni ve rs it y of m ic hi ga n e- jo ur na l pa ck ag e fr om w w w .l ie be rt pu b. co m a t / / . f or p er so na l us e on ly . cultivating jatropha curcas on de- graded land could also increase car- bon sequestration, given that the jatropha curcas would be growing where other plants could not. how- ever, some of the land included in the potential deal with naloil is produc- tive farming land, meaning that chief ofori not only had to contend with the potential loss of land for food crops but would also have to evict the land’s tenants. finally, jatropha curcas can be an aggressive, invasive species. this is especially problematic when com- bined with the negative impacts of deforestation and of monocropping typically associated with jatropha curcas plantations. sitting back for a moment, chief ofori took stock of everything he had reviewed. assessing the impact on the local population throughout ghana, the commercial production of jatropha curcas re- quires companies such as naloil to make large acquisitions of land. selling this land would have signifi- cant impacts on the livelihoods of local communities and farmers. chief ofori had learned of a study conducted by the renewable natural resources department at kwame nkrumah university of science and technology in which percent of the study’s respondents reported having lost land to jatropha curcas- producing plantations, and per- cent reported having lost over acres of land. ten acres was probably nothing to a company like naloil, but it was a tremendous amount of land for a small farmer. although jatropha curcas could be grown on marginalized lands, the land acquired for its production was often productive land used for cul- tivating crops such as maize, yam, plantain, and cocoa. in many cases, such acquisition had forced farmers onto less fertile lands where their crops did not grow as plentifully. these land issues had in some in- stances led to violent conflicts, both between locals and company offi- cials and among locals themselves due to the clearing of boundary markers between previously locally owned lands. chiefs such as chief ofori had the authority to sell land without con- sulting their people, so many never did. in fact, percent of the re- spondents in the kwame nkrumah university study reported this to have been the case. even chief ofori, when he had met with the men from naloil earlier that day, had been a mere signature away from selling a significant portion of his people’s land and had not consulted his peo- ple. he had considered opening the decision-making process to the community, but ultimately the deci- sion and the responsibility for that decision fell on his shoulders. the same study indicated that many locals had been either inadequately compensated or not compensated at all for land lost: percent reported that they had received no compen- sation for their lost land, and percent of those who had received something claimed it was inadequate or forced upon them. additionally, the loss of land decreased food se- curity in affected communities due in part to the decrease in fallow periods that led to sharp declines in farm yields. households reported that loss of land had greatly decreased their ability to meet their own needs for food. representatives from naloil had promised chief ofori that compensation for all land lost would be given. however, he had serious reservations about trusting the company, given stories he’d read about locals not getting prop- erly paid. chief ofori had also tried to compile information about possible positive impacts on the community, which naloil’s representatives had gone out of their way to emphasize to him. for example, jatropha curcas plan- tations often did create additional employment opportunities for communities. a significant propor- tion of plantation workers were employed from local communities, and of the employed respondents in the aforementioned dutch study, percent claimed to work full time, and the other percent worked part time, seasonally, intermittently, or as a one-time activity. pay de- pended on whether workers were casual or permanent, on whether they were part- or full-time, and on their occupations (field worker, machine operator, field manager, etc.). however, salaries generally needed to be supplemented with fishing and/or farming to provide a sufficient annual income. still, de- spite the additional wages, locals generally reported feeling less well- off financially after the establish- ment of jatropha curcas plantations. this decline was attributed once again to the large swaths of land lost. the dutch research also highlighted many other impacts on local in- frastructures and economies from jatropha curcas plantations. for in- stance, percent of respondents reported that the activities of ja- tropha curcas companies had pro- vided their communities with wells, boreholes, and dugouts for water. in some instances, the jatropha curcas companies had contributed to the building of schools and clinics, and to road maintenance. however, while sustainability mary ann liebert, inc. • vol. no. • february • doi: . /sus. . .eo oliphant et al. d ow nl oa de d by u ni ve rs it y of m ic hi ga n e- jo ur na l pa ck ag e fr om w w w .l ie be rt pu b. co m a t / / . f or p er so na l us e on ly . development projects were almost always promised to communities and chiefs before land purchases were made (hence giving the chief further incentive to sell the land), the com- panies rarely followed through on these promises. in many cases, even if a company intended to complete these projects, the plantation could be shut down and the community abandoned by the company before the projects were completed. another possible benefit ofori had considered was increased access to biofuel for generators. generators powered by jatropha curcas biodiesel produced in the community could substantially increase access to elec- tricity, meaning more time for kids to study at night as well as access to power for refrigeration. the abil- ity to employ biofuel generators could have far-reaching effects in his community. naloil had assured chief ofori that they would acknowledge their re- sponsibilities to his community, and that they would strive to exceed national and international regu- lations and standards regarding these responsibilities. but when broken promises were the prece- dent, he wondered how he could trust naloil to follow through on those words. a decision to be made after spending the majority of the day reviewing his research, chief ofori retired to his bed, burdened still by the decision he had not yet made. he contemplated the poten- tial benefits of agreeing to this deal. it would bring money to the com- munity immediately. employment could boom. schools could be built and could improve education in the community. new investments and development could revitalize local infrastructure. access to power in agogo was limited, so the potential for local jatropha curcas biodiesel to power generators in the com- munity could increase the quality of life immensely. if the deal with naloil resulted in even one or two of these outcomes, it would be a boon to agogo and all who in- habited it. there were potential downsides to consider as well. could he trust this company to carry out its promises? from what he had read, the answer was ambiguous. some of his people might be pushed from their land, and would they receive just com- pensation? some might be forced to cultivate infertile land, which would put their ability to make a living in great jeopardy. the plantations might degrade the surrounding en- vironment if the company did not follow the strict policies that it claimed it would. this was the dilemma. there was so much uncertainty as to what out- comes would result from his deci- sion, but he had to choose: take the risk of making this deal, or let it slip away. he knew that no matter what he decided the next day, the most im- portant thing to consider was the impact of his actions on all those who relied on him to guide their community. it was a tremendous responsibility. he closed his eyes, settling in for what would surely be a fitful sleep. references . ghana web. akosombo dam faces shutdown. dec. , . https://www.ghanaweb.com/ghana homepage/newsarchive/akosombo- dam-faces-shutdown- (last accessed / / ). . dogbevi, emmanuel k. ghana produces million barrels of oil since first drill in . ghana business news, july , . https:// www.ghanabusinessnews.com/ / / /ghana-produces- -million- barrels-of-oil-since-first-drill-in- / (last accessed / / ). . energy commission, ghana. energy (supply and demand) out- look for ghana. april . http:// www.energycom.gov.gh/files/energy % commission% -% energy % outlook% for% ghana_final .pdf (last accessed / / ). . african development bank group. ghana economic outlook. . https://www.afdb.org/en/countries/ west-africa/ghana/ghana-economic- outlook/ (last accessed / / ). . u.s. energy information admin- istration. diesel fuel explained. https://www.eia.gov/energyexplained/ index.cfm?page=diesel_use (last accessed / / ). address correspondence to: adam c. simon north university avenue c. c. little ann arbor, mi - e-mail: simonac@umich.edu to access the podcast and further materials on this case and other michigan sustainability cases, visit: http://www.learngala.com mary ann liebert, inc. • vol. no. • february • doi: . /sus. . .eo sustainability biofuels: beneficial or bad? d ow nl oa de d by u ni ve rs it y of m ic hi ga n e- jo ur na l pa ck ag e fr om w w w .l ie be rt pu b. co m a t / / . f or p er so na l us e on ly . targets for onboard hydrogen storage systems for light-duty vehicles target explanation document: onboard hydrogen storage for light-duty fuel cell vehicles this target explanation document is a document of the u.s. drive partnership. u.s. drive (driving research and innovation for vehicle efficiency and energy sustainability) is a voluntary, non-binding, and non-legal partnership among the u.s. department of energy; uscar, representing fca us llc, ford motor company, and general motors; five energy companies – bp america, chevron corporation, phillips company, exxonmobil corporation, and shell oil products us; two utilities – southern california edison and dte energy; and the electric power research institute (epri). the hydrogen storage tech team is one of u.s. drive technical teams that work to accelerate the development of pre-competitive and innovative technologies to enable a full range of efficient and clean advanced light-duty vehicles, as well as related energy infrastructure. for more information about u.s. drive, please see the u.s. drive partnership plan, www.vehicles.energy.gov/about/partnerships/usdrive.html or www.uscar.org http://www.vehicles.energy.gov/about/partnerships/usdrive.html http://www.uscar.org/ table of contents . background.………………………………………………………………………………………………….…. . target table………………………………………………………………………………………………….…. . summary of new / revised targets….....……………………...………………………………….…. . assumptions..………………………….…………………………………………………………………….…. . detailed breakdown of targets..…………………………………………………………………….…. . background: hydrogen (h ) storage is a key enabling technology for the advancement of hydrogen vehicles in the automotive industry. storing enough hydrogen ( - kg) onboard a light-duty vehicle to achieve a to mile driving range is a significant challenge. on a weight basis, hydrogen has nearly three times the energy content of gasoline when comparing lower heating values ( kwh/kg for h compared to kwh/kg for gasoline). however, on a volume basis, the situation is reversed (approximately . kwh/l for bar h at °c compared to . kwh/l for gasoline). in addition to energy density, hydrogen storage systems face challenges related to cost, durability/operability, charge/discharge rates, fuel quality, efficiency, and safety, which may limit widespread commercialization of hydrogen vehicles. hydrogen storage activities within the u.s. drive partnership, in conjunction with the doe’s fuel cell technologies office (fcto) in the office of energy efficiency and renewable energy, are focused on applied research and development (r&d) of technologies that can achieve a to mile driving range for the full span of light-duty vehicles, while meeting packaging, cost, safety, and performance requirements. such technologies, incorporated within a fuel cell vehicle, would be competitive with incumbent vehicle technologies as illustrated in figure . figure : distribution of light-duty vehicle sales in the u.s. market by driving range (epa label range) from conventional vehicle data, the driving range of miles has been identified as the minimum entry point for the market. in comparison, hydrogen vehicles in doe’s controlled hydrogen fleet and infrastructure demonstration and validation project had an environmental protection agency (epa) adjusted driving range from miles (generation observed minimum) to miles (generation http://www.uscar.org/guest/partnership/ /us-drive http://energy.gov/eere/fuelcells/fuel-cell-technologies-office courtesy of marc melaina / eleftheria kontou (nrel) and david greene (anl) , , , , , , , , , , , l ig ht -d ut y sa le s range (miles) epa label range source: polk data, http://www.uscar.org/guest/partnership/ /us-drive http://energy.gov/eere/fuelcells/fuel-cell-technologies-office observed maximum). since this demonstration fleet, there have been examples of fuel cell vehicles that have approached or exceeded the minimum driving range target of miles, even though significant effort regarding cost and packaging is still required to achieve commercial viability across various vehicle classes. thus, it is clear that hydrogen storage systems must be improved in order to provide the customer with the expected driving range across all vehicle platforms. to address all of these various challenges, hydrogen storage system performance targets for light-duty vehicles were developed through the u.s. drive as shown below in table . the targets apply to system-level properties and are customer and application driven. it is intended that u.s. drive will review and update the hydrogen storage system targets approximately every years to assess technology improvements and to ensure continued alignment with market driven requirements. additional information on the u.s. drive partnership can be found in the hydrogen storage technical team roadmap. in addition, further information on fcto’s hydrogen storage program can be found in the multi-year research, development, and demonstration plan. the original targets were set in based on attempting to be competitive with conventional gasoline fuel systems and revised in to enable greater than -mile range within the allocated package space and weight for hydrogen storage systems in representative fuel cell vehicles. although hydrogen storage systems have shown continuous improvement since and many targets have been met in isolation, further advancements are still needed to meet all of the performance targets simultaneously. the automotive original equipment manufacturers (oems) have introduced many fuel cell electric vehicles (fcevs) to a wide range of prospective customers since the original targets were formulated. valuable information has been and continues to be gathered with regard to vehicle performance and customer requirements and expectations. from the experience gained with fcev fleets and continued hydrogen storage system development, the targets have been further refined to align with these current advancements and implementation. almost all fcevs demonstrated to date have employed some degree of hybridization. speculation on the effects of heavily hybridized vehicles (e.g. plug-ins, range extended etc.) was minimized in the development of these targets. if included in the future for consideration in the target calculation assessments, significant hybridization can both positively and negatively impact the suggested hydrogen storage system requirements and performance. for example, a -mile all electric range extended vehicle would reduce the hydrogen storage system range requirement by approximately percent and potentially relax start-up time and system response, however it would also compete for packaging volume, weight, and cost. this document presents the onboard hydrogen storage for light-duty fuel cell vehicles technical targets, describes the relevant changes since the last major target revision was completed in , and describes in length the details behind each target. national renewable energy laboratory, “innovation for our energy future,” http://www.nrel.gov/hydrogen/docs/cdp/cdp_ .ppt. http://www .eere.energy.gov/vehiclesandfuels/pdfs/program/hstt_roadmap_june .pdf http://energy.gov/sites/prod/files/ / /f /fcto_myrdd_storage.pdf http://www.nrel.gov/hydrogen/docs/cdp/cdp_ .ppt http://www .eere.energy.gov/vehiclesandfuels/pdfs/program/hstt_roadmap_june .pdf http://energy.gov/sites/prod/files/ / /f /fcto_myrdd_storage.pdf . target table: table . technical system targets: onboard hydrogen storage for light-duty fuel cell vehicles a (updated may ) storage parameter units ultimate system gravimetric capacity: kwh/kg . . . usable, specific-energy from h (net useful energy/max system mass) b (kg h /kg system) ( . ) ( . ) ( . ) system volumetric capacity: kwh/l . . . usable energy density from h (net useful energy/max system volume) b (kg h /l system) ( . ) ( . ) ( . ) storage system cost : $/kwh net ($/kg h ) • fuel cost c $/gge at pump durability/operability: • operating ambient temperature d °c - / (sun) - / (sun) - / (sun) • min/max delivery temperature °c - / - / - / • operational cycle life ( / tank to full) cycles • min delivery pressure from storage system bar (abs) • max delivery pressure from storage system bar (abs) • onboard efficiency e % • “well” to powerplant efficiency f % charging / discharging rates: • system fill time g min - - - • minimum full flow rate (e.g., . g/s target for kw rated fuel cell power) (g/s)/kw . . . • average flow rate (g/s)/kw . . . • start time to full flow ( °c) s • start time to full flow (- °c) s • transient response at operating temperature %– % and %– % (based on full flow rate) s . . . fuel quality (h from storage) h: % h meet or exceed sae j dormancy: i • dormancy time target (minimum until first release from initial % usable capacity) • boil-off loss target (max reduction from initial % usable capacity after days) days % environmental health & safety: • permeation & leakage j - • meet or exceed sae j for system safety • meet or exceed applicable standards • conduct and evaluate failure analysis • toxicity - • safety - useful constants: . kwh/mj; lower heating value for h is . kwh/kg h ; kg h ≈ gal gasoline equivalent (gge) on energy basis footnotes to target table: a for a normalized comparison of system performance to the targets, a usable h storage capacity of . kg h should be used at the lower heating value of hydrogen ( . kwh/kg h ). targets are for a complete system, including tank, material, valves, regulators, piping, mounting brackets, insulation, added cooling capacity, and all other balance-of-plant components. all capacities are defined as usable capacities that could be delivered to the fuel cell system. all targets must be met at the end of service life. b capacities are defined as the usable quantity of hydrogen deliverable to the fuel cell system divided by the total mass/volume of the complete storage system, including all stored hydrogen, media, reactants (e.g., water for hydrolysis-based systems), and system components. capacities must be met at end of service life. tank designs that are conformable and have the ability to be efficiently package onboard vehicles may be beneficial even if they do not meet the full volumetric capacity targets. c hydrogen threshold fuel cost is calculated to be competitive with a gasoline hybrid vehicle, and thus is independent of pathway. it is defined as the untaxed cost of hydrogen produced, delivered, and dispensed to the vehicle [http://hydrogen.energy.gov/pdfs/ _h _threshold_costs.pdf]. for material-based storage technologies, the impact of the technology on the hydrogen threshold fuel cost (e.g., off-board cooling, off- board regeneration of chemical hydrogen storage materials, etc.) must be taken into account. d stated ambient temperature plus full solar load (i.e., full exposure to direct sunlight). no allowable performance degradation from - °c to °c. allowable degradation outside these limits is to be determined. e onboard efficiency is the energy efficiency for delivering hydrogen from the storage system to the fuel cell powerplant, i.e., accounting for any energy required operating pumps, blowers, compressors, heating, etc. required for hydrogen release. f well-to-powerplant efficiency includes onboard efficiency plus off-board efficiency, i.e., accounting for the energy efficiency of hydrogen production, delivery, liquefaction, compression, dispensing, regeneration of chemical hydrogen storage materials, etc. as appropriate. h a and hdsam analyses should be used for projecting off-board efficiencies. efficiencies less than the target may be acceptable if evidence can be given that well-to-powerplant carbon intensity (including delivery and dispensing of h ) can achieve less than kg co e/kg h . argonne national laboratory’s greet model (https://greet.es.anl.gov/) should be used to calculate the carbon intensity of well-to-powerplant energy use. g when applicable, the fill time should comply with sae j , the fueling protocol for light-duty gaseous hydrogen surface vehicles. h hydrogen storage systems must be able to deliver hydrogen that meets acceptable hydrogen quality standards for fuel cell vehicles (see sae j and iso/pdts - ). note that some storage technologies may produce contaminants for which effects are unknown and not addressed by the published standards; these will be addressed by system engineering design on a case-by-case basis as more information becomes available. i dormancy targets assume vehicle is parked in °c ambient temperature and dormancy performance is maintained over the year life of the vehicle. j total hydrogen lost into the environment as h ; relates to hydrogen accumulation in enclosed spaces. storage systems must comply with applicable standards for vehicular fuel systems including but not limited to sae j and the united nations global technical regulation no. (hydrogen and fuel cell vehicles). this includes any coating or enclosure that incorporates the envelope of the storage system. http://hydrogen.energy.gov/pdfs/ _h _threshold_costs.pdf https://greet.es.anl.gov/ http://standards.sae.org/j _ / http://standards.sae.org/j _ https://www.iso.org/standard/ .html http://standards.sae.org/j _ . summary of new / revised targets: since the last major target revision in , significant progress has been made on the development and implementation of fcevs thus necessitating the need to add and revise several targets. tables and below provide a summary of the various targets that have been revised and added since the last major target update in . note that in , the targets were developed for and “ultimate full fleet” targets were added to capture virtually all light-duty vehicle platforms (“significant market penetration”). the original targets were developed based on an assumption that the doe funding for hydrogen storage research and development would remain fairly constant. since , funding for the doe hydrogen storage program has been at reduced levels as shown by the doe hydrogen and fuel cells program record # (https://www.hydrogen.energy.gov/pdfs/ _historical_fuel_cell_h _budgets.pdf), thus impacting the ability to meet the targets and shifting these targets to , which were added to table . table . revised technical system targets: onboard hydrogen storage for light-duty fuel cell vehicles storage parameter units (previous) (new) (new) ultimate (previous) ultimate (new) notes system gravimetric capacity: kwh/kg . . . . . previous target shifted to target usable, specific-energy from h (net useful energy/max system mass) b (kg h /kg system) ( . ) ( . ) ( . ) ( . ) ( . ) system volumetric capacity: kwh/l . . . . . previous target shifted to target usable energy density from h (net useful energy/max system volume) b (kg h /l system) ( . ) ( . ) ( . ) ( . ) ( . ) storage system cost : $/kwh net tbd tbd cost target provided in was tbd ($/kg h ) tbd tbd • fuel cost c $/gge at pump - - both and ultimate targets were revised to be consistent with hptt goal durability/operability: unchanged; only ultimate target was revised • min delivery pressure from storage system bar (abs) charging / discharging rates: both and ultimate targets were revised • system fill time min . - - . - https://www.hydrogen.energy.gov/pdfs/ _historical_fuel_cell_h _budgets.pdf table . new technical system targets: onboard hydrogen storage for light-duty fuel cell vehicles storage parameter units (new) (new) ultimate (new) notes charging / discharging rates: new target to differentiate between average flow rate & minimum full flow rate • average flow rate (g/s)/kw . . . dormancy: • dormancy time target (minimum until first release from initial % usable capacity) • boil-off loss target (max reduction from initial % usable capacity after days) days % new targets to address dormancy (challenge for system operating at less than ambient temperate) in addition to the changes noted above, the target for release of hydrogen was removed for clarity as this system metric is now more specifically covered by the targets for dormancy as well as permeation and leakage. also, targets relating to internal combustion engine were removed. at one time, hydrogen powered internal combustion engines (ice) were seen as a logical evolution step to fuel cell vehicles powered by hydrogen. focus has shifted entirely to fcevs and thus there is no longer a need to include specific targets as related to ices. as a result all hydrogen storage system targets related to ices have been removed. further explanation of the new and modified targets are included in section . which provides a detailed breakdown of the individual targets. . assumptions: . all targets must be met simultaneously on a total system level. the performance targets apply to a complete storage system, including the tank, storage media, safety system, valves, regulators, piping, mounting brackets, insulation, added cooling capacity, and any other necessary balance-of-plant components (see figure below for example system diagrams showing single-tank and dual-tank configurations with necessary balance-of-plant components). . targets are based on what is required to meet the application requirements and customer expectations; not on what the state-of-the-art technology can achieve. . the targets should enable greater than -mile range across the majority of the current light- duty vehicle fleet (i.e. many makes and models). . the targets are based on providing a sufficient amount of net available hydrogen onboard the vehicle to satisfy driving range. . these targets must be maintained until the end of the vehicle’s service life. . depending on progress in other areas related to fcev development, these targets may have to be altered and will be periodically revisited approximately every years. . a wide variety of vehicle types from small subcompact cars to light-duty trucks were considered in the target calculations; the fuel storage requirement varied between approximately to kg of hydrogen, based on the corresponding vehicle type (class) and expected driving range. . the targets include the "ultimate full fleet” targets. the “ultimate full fleet” targets are meant to capture virtually all light-duty vehicle platforms (“significant market penetration”). the “ultimate full fleet” target is intended to facilitate the introduction of hydrogen-fueled propulsion systems across the majority of vehicle classes and models. . some volumetric allowance can be adopted in the targets for conformable (geometrically speaking) storage systems. the volumetric and gravimetric targets (revised approach in ) utilized the packaging and design space allotted for compressed hydrogen storage in the actual fuel cell demonstration fleet vehicles. that is, the majority of vehicles in the fleet have demonstrated the oems’ abilities to design and modify vehicle architecture around the hydrogen systems. two examples of such modifications include the redesign of floor pan to accommodate larger hydrogen storage systems and the alteration in vehicle architecture to accommodate fuel cell/electronic systems components. varying degrees of increased mass and volume acceptance (due to the fuel cell and h storage systems) have been demonstrated in these vehicles. experience has shown that it is generally easier to accommodate extra weight compared to extra volume (i.e., accommodating additional packaging volume is more challenging). importantly, all vehicle modifications must be performed without making compromises to customer expectations for cargo/passenger space, performance, or safety. figure a: example bar hydrogen storage system diagram showing a single-tank configuration figure b: example bar hydrogen storage system diagram showing a dual-tank configuration g. ordaz, c. houchins, and t. hua, “onboard type iv compressed hydrogen storage system – cost and performance status ,” doe hydrogen and fuel cells program record # , nov. , . https://www.hydrogen.energy.gov/pdfs/ _onboard_storage_performance_cost.pdf https://www.hydrogen.energy.gov/pdfs/ _onboard_storage_performance_cost.pdf . detailed breakdown of the individual targets: the following section provides the detailed background and explanation for each target in table . for a normalized comparison to these targets, a usable hydrogen storage capacity of . kg hydrogen should be used at lower heating value of hydrogen ( . kwh/kg hydrogen). in addition, the targets are for a complete system, including tank, material, valves, regulators, piping, mounting brackets, insulation, added cooling capacity, and all other balance-of-plant components. all capacities are defined as usable capacities that could be delivered to the fuel cell system and all targets must be met at the end of service life. while certain targets are expressed in terms of kwh/kg, kwh/l and $/kwh, it should be acknowledged that the hydrogen system is not exactly scalable by the useable capacity since the balance-of-plant components will be fixed regardless of the capacity. based on this understanding that hydrogen systems have a scalable and fixed element, a target comparison based on the absolute weight, volume, and cost can also be performed to allow for the practical application of onboard efficiency advancements and acceptable limits for actual storage systems. storage parameter units ultimate system gravimetric capacity: kwh/kg . . . usable, specific-energy from h (net useful energy/max system mass) (kg h /kg system) ( . ) ( . ) ( . ) system gravimetric capacity: this is a measure of the specific energy from the system standpoint of net useful energy per total onboard storage system mass, not just the storage medium. the term specific energy is used interchangeably with the term gravimetric capacity. “net useful energy” excludes unusable energy (i.e. hydrogen left in a tank below minimum fuel cell system pressure, flow, and temperature requirements) and energy used to extract the hydrogen from the storage medium (e.g. fuel used to heat a hydride or material to initiate or sustain hydrogen release). the system gravimetric capacity refers to end of life net available capacity. the storage system is all encompassing meaning it includes everything necessary for the storage system. this includes, but is not limited to: interfaces with the refueling infrastructure, safety features, storage vessel, storage media, insulation or shielding, temperature/humidity management equipment, regulators, electronic controllers, sensors, all onboard conditioning equipment necessary to store the hydrogen (compressors, pumps, filters, etc.), and the mounting hardware and delivery piping. the target is in units of net useful energy in kwh per maximum system mass in kg. “maximum system mass” implies that all of the equipment enumerated above plus the maximum charge of hydrogen are included in the calculation. reactive systems may increase in mass as they discharge hydrogen; in such systems the post hydrogen discharged mass must be used. table : second generation lower "gen "* upper "gen "* commerical example fuel economy mi/kg h range mi h capacity kg h . . . gravimetric capacity wt% h . . . volumetric capacity kg h /l . . . storage system mass kg storage system volume l *ol d data bas ed on doe's nati onal hydrogen learni ng demons trati on range of values fcev data units vehicle data from the doe “national hydrogen learning demonstration” project to determine the capacity targets developed back in , data from operational fuel cell fleet vehicles associated with the doe “national hydrogen learning demonstration” were used, including small, compact, mid-size and crossover light-duty vehicles. the vehicles had a varied degree of hybridization. as shown in table , these vehicles were unable to achieve the expected driving range, which in north american is miles (at a minimum) up to nearly miles for the light-duty vehicle market. based on the allocated weight for hydrogen storage systems, the targets were determined by calculating the increased capacity required to allow these fuel cell vehicles to meet the desired driving range within the current vehicle using the fixed allocation for system weight. from these initial fleet examples, recent fuel cell vehicles have demonstrated improvements in fuel economy (e.g. toyota mirai ) with the capability of achieving over a mile range. therefore, the upper range vehicle example in table can be replaced with these recent vehicle data (e.g. miles/gge) along with the respective hydrogen storage allocations (e.g. . kg useable capacity, kg). the target values were modified based on these recent fuel cell vehicles. the gravimetric targets aligned directly with these current storage system examples capable of achieving the minimum of miles. the target was based on achieving a mile driving range using the current fuel cell electric vehicle example in the table for the upper values, which results in a hydrogen capacity of . kg to . kg. using this capacity and the weight allocation ( kg to kg), the resulting average gravimetric capacity target is . wt%. the same approach was used for the ultimate target based on a mile driving range resulting in a target value of . wt%. storage parameter units ultimate system volumetric capacity: kwh/l . . . usable energy density from h (net useful energy/max system volume) (kg h /l system) ( . ) ( . ) ( . ) system volumetric capacity: this is a measure of energy density from a system standpoint of net useful energy per onboard storage system volume, rather than from a storage media standpoint. the term energy density is used interchangeably with the term volumetric capacity. as noted above, the onboard hydrogen storage system includes every component required to safely accept hydrogen from the delivery infrastructure, store it onboard, and release conditioned hydrogen to the fuel cell system. also, as before, any unusable estimates based on data from http://www.fueleconomy.gov/feg/fcv_sbs.shtml and other available information http://www.fueleconomy.gov/feg/fcv_sbs.shtml fuel must be taken into account and storage system volumetric capacity refers to end of life net available capacity. today’s gasoline tanks are considered conformable. for conformable tank concepts, the required volumetric energy density may be reduced because space not allocated for fuel storage may be used without a penalty. the system volumetric capacity refers to end of life net available capacity. the volume should be considered as the external water displacement volume of the entire system. the targets are in units of net usable energy in kwh per system volume in liters. as discussed for gravimetric capacity, data from operational fuel cell fleet vehicles associated with the doe “national hydrogen learning demonstration” was used to determine the volumetric capacity targets developed back in . in the same manner, the targets were determined by calculating the increased capacity required to allow these fuel cell vehicles to meet the desired driving range within the current vehicle using the fixed allocation for system volume. as recognized in the gravimetric target explanation, the fuel economy of recent fuel cell vehicles (e.g. toyota mirai) have improved since the demonstration vehicles noted in table with the capability of achieving just over miles driving. this improvement allows for the upper range vehicle in table to be replaced with these recent vehicle data (e.g. miles/gge) along with the respective hydrogen storage allocations (e.g. . kg useable capacity). the target values were modified based on these recent fuel cell vehicles. the gravimetric targets aligned directly with these current storage system examples capable of achieving the minimum of miles with a % correction factor. the correction factor adjustment is motivated by two key points. first, as the volumes quoted in table refer to exact or water volumes, they represent the minimum volume required by the storage vessel. the practical enclosure volume available onboard the vehicle is typically less. in fact, the examples in the fleet fuel cell vehicles had notable intrusion into the customer or cargo space. the correction factor to estimate the packaging inefficiency may vary significantly based on the type of vehicle platform and design requirements of each oem. second, vehicles in the doe demonstration dataset along with recent vehicles are suv-type or large sedan vehicles. packaging of hydrogen storage systems in these larger vehicles will generally be easier than in smaller ones. taking these two points into account, a target value slightly higher than the represented volumes was adopted based on these correction factors. similar to the gravimetric target explanation, the target was based on achieving a mile driving range requiring between . kg to . kg useable hydrogen based on the fuel cell electric vehicle examples in the table with the replacement of the recent fuel vehicle attributes for the upper values. using this capacity and the volume allocation ( l to l) along with the correction factor, the resulting average volumetric target is . kg/l. the same approach was used for the ultimate target based on a mile driving range resulting in a target value of . kg/l. storage parameter units ultimate storage system cost : $/kwh net ($/kg h ) • fuel cost $/gge at pump storage system cost: this is the cost of the entire hydrogen storage system including the initial charge hydrogen. as noted above, the onboard hydrogen storage system includes every component required to safely accept hydrogen from the delivery infrastructure, store it onboard, and release conditioned hydrogen to the fuel cell system. u.s. drive performed extensive modeling to evaluate the targets for advanced vehicle technologies, including fcevs. the purpose of the analysis was to provide guidance for the u.s. drive targets, such that vehicles using the advanced technologies being developed through the u.s. drive partnership would be comparable on a cost (initial + operational) and performance basis to incumbent technology by . the effort considered three levels of technology advancement, %, % and % confidence levels with % being the most aggressive within the timeframe based on a high volume assumption of , units produced per year. the levelized cost of driving for the analysis was developed based on midsize vehicle using annual energy outlook (aeo ) high oil scenario for gasoline in ($ . /gallon of gasoline), , miles per year, -year payback period, and % discount rate. figure provides the levelized cost results at the % confidence level for the fcev compared to an advanced spark ignition (adv si) and hybrid electric (si hev) vehicle. from this analysis, the fuel cell vehicle at the baseline would require cost reductions to be competitive on a levelized cost of driving. the u.s. drive analysis for the fc hev baseline assumed a hydrogen fuel cost of $ . per gallon gasoline equivalent ( kg h is approximately gge); fuel cell system costs of $ /kw; and onboard hydrogen storage system costs of $ /kwh ($ /kg h ). after adjusting the fc hev assumptions to the department of energy’s fuel cell system target of $ /kw, a hydrogen storage system cost target of $ /kwh would enable an fcev to approach the levelized cost of the si hev at the % confidence level and adv si at the % confidence level. for a competitive levelized cost to a adv si, the fuel cell system would need to achieve their ultimate target of $ /kw and the onboard hydrogen storage system would require a cost target of $ /kwh, which is also shown in figure as a comparison to the baseline gasoline vehicle levelized cost. therefore onboard hydrogen storage cost targets of $ /kwh as an intermediate target in , $ /kwh in , and $ /kwh as a long-term ultimate target are appropriate. figure : levelized cost of driving analysis for a fc hev with baseline, targets, and ultimate target assumptions in comparison to adv si and si hev to establish the onboard hydrogen storage system cost targets • fuel cost: this target includes costs for producing, compressing, liquefying, transporting and . . . . . . . . . adv si si hev fc hev baseline fc hev targets fc hev ultimate targets le ve liz ed c os t o f d ri vi ng (n pv $/ m i) u.s. drive levelized cost of driving analysis for midsize vehicle fuel cost (npv) drive, wheels, tires, etc. transmission motor energy storage fuel tank fuel cell emission control ice glider distributing, dispensing, chemical recovery, etc., as applicable for the fuel. for material-based storage, if the fuel / storage system utilized, requires additional processing such as off-board cooling or off-board regenerated of spent fuel (e.g., chemical hydrogen storage material), then those extra costs (e.g., regeneration) must be included within the fuel cost. the storage system cost also includes the first charge of fuel as mentioned above. the unit of $/gallon gasoline equivalent (gge) is approximately equivalent to $/kg of hydrogen. storage parameter units ultimate durability/operability: • operating ambient temperature °c - / (sun) - / (sun) - / (sun) • min/max delivery temperature °c - / - / - / • operational cycle life ( / tank to full) cycles • min delivery pressure from storage system bar (abs) • max delivery pressure from storage system bar (abs) • onboard efficiency % • “well” to powerplant efficiency % durability / operability: • operating ambient temperature: the storage system must dependably store and deliver hydrogen to the fuel cell system at all expected ambient conditions. the temperature units are degrees celsius (°c). the notation (sun) indicates that the upper temperature is a hot soak condition in full direct sun, including radiant heat from the pavement. note that storage operating temperatures in excess of °c can be achieved with solar loading. thus the hydrogen storage system design should include a shield from this radiant heat or be designed to accommodate temperatures greater than °c. also note that there is no allowable performance degradation between – °c and °c. allowable degradation outside these limits is to be determined. • min/max delivery temperature: this target refers to the inlet temperature of hydrogen to the fuel cell system. fuel cells currently operate at approximately °c. any hydrogen entering above the fuel cell operating temperature would add to the already significant water management and heat rejection requirements of the fuel cell system. thus, an upper limit on temperature is desirable. the value of °c is selected based on today’s proton exchange membrane (pem) fuel cell technology. as the fleet size is increased, it will also become increasingly important that the storage system comply more closely with the fuel cell preferred operating range. the lower limits reflect both wider acceptance of fuel cells in varying climates and fuel cell improvements for lower temperature operation. the temperature units are degrees celsius (°c). • operational cycle life: this target refers to the minimum cycle life for the performance of the storage material/media. the number of operational cycles is calculated as the design lifetime mileage of the vehicle divided by the effective range of the vehicle. customers expect the fuel system to last the life of the vehicle and typically , miles represents the minimum lifetime. assuming a -mile range, this amounts to full fill cycles as a minimum. however, many customers fill at partial capacity rather than at empty and extend the vehicle mileage beyond the minimum lifetime, requiring more fill cycles. the sierra research report no. https://energy.gov/sites/prod/files/ / /f /fcto_myrdd_delivery.pdf sr - - for the california air resource board ( ) on vehicle lifetime mileage indicated all scrapped vehicles had mileage below , miles ( -sigma value was , miles). using this maximum lifetime mileage and the partial cycle definition from a quarter full to full tank, the effective range is reduced to miles resulting in the , cycle life target. this target is not equivalent to the durability test cycles, which require significantly more cycles to ensure safe performance. the safety critical components (i.e. cylinder, relief valves, etc.) involved in managing pressure and temperature conditions need additional durability cycle life as specified in the applicable codes and standards (i.e. sae j and the united nations global technical regulation ece/trans/ /add. ). • minimum delivery pressure from storage system: this target acknowledges that the onboard hydrogen storage system is responsible for delivering hydrogen in a condition that the fuel cell system can use. since there can be no flow without a pressure differential, a minimum supply pressure is required just to move the hydrogen from the bulk storage to the fuel cell system. if the hydrogen were merely available at the entrance to a fuel cell system (i.e., less than bar), then any pumps necessary to push or draw that fuel through the stack would be considered part of the fuel storage system. the pressure units are in gauge bar (bar). the ultimate target for the minimum delivery pressure from the storage system was updated from bar to bar. it should be recognized the delivery pressure is at the interface between the hydrogen storage system and the fuel cell system rather than directly to the fuel cell stack. the delivery pressure to the fuel cell system requires higher pressure than the operating conditions of the stack for pressure drop and passive recirculation within the fuel cell system balance of plant. in some fuel cell system designs, the desire is to increase this minimum delivery pressure even greater than bar in order to further optimize the performance. therefore, the ultimate target was updated to bar to acknowledge the current direction for fuel cell system requirements and provide a consistent minimum delivery pressure throughout the target table. • maximum delivery pressure from storage system: this target is for the pressure delivered from the onboard hydrogen storage system to the fuel cell system. this target ensures that the onboard hydrogen storage system regulates the pressure before fuel is supplied to the fuel cell system. • onboard efficiency: hydrogen storage systems must be energy efficient. to ensure this, a target has been set for the efficiency of the storage system onboard the light-duty vehicle. it is defined as the ratio of the total amount of energy delivered to the fuel cell system (lower heating value) compared to the total energy contained in the tank (based on the tank rating). for onboard reversible storage systems, the target is greater than % energy efficiency for the energy delivered to the fuel cell system from the onboard storage system. for example, if a storage tank is rated as holding . kg usable hydrogen, the total amount of energy in the rated tank would be . kg multiplied by ( . kwh/kg) or approximately . kwh. for the target to be achieved, at least % of . kwh or kwh needs to be delivered to the fuel cell system. • “well” to powerplant efficiency: well-to-powerplant efficiency includes onboard efficiency plus off-board efficiency, i.e., accounting for the energy efficiency of hydrogen production, delivery, liquefaction, compression, dispensing, regeneration of chemical hydrogen storage materials, etc. as appropriate. the energy content of the hydrogen delivered to the automotive powerplant should be greater than % of the total energy input to the process. h a and hdsam analyses should be used for projecting off-board efficiencies. efficiencies less than the target may be acceptable if evidence can be given that the carbon intensity (including delivery and dispensing of hydrogen) can achieve less than kg co e/kg h (i.e., conceivable that a system is inefficient, but still allows for reduced greenhouse gas emissions). argonne national laboratory’s greet model (https://greet.es.anl.gov/) should be used to calculate the carbon intensity of energy use for hydrogen delivery and dispensing (from bar, and ambient temperature of produced hydrogen). default energy shares and efficiency values in greet, when applicable, should be used for calculating carbon intensity. to liquefy and dispense hydrogen, about - kwh of electricity are needed for liquefaction and pumping (depending on the scale and technology of liquefaction). using the current ( ) carbon intensity of the u.s. electricity grid mix of about g co e/kwh, the carbon intensity of delivering and dispensing liquid hydrogen is - kg co /kg h . this is true whether liquid pumping was used for bar cryo-compressed dispensing, or in conjunction with a heat exchanger for bar gaseous dispensing. the corresponding electricity consumption for tube- trailer delivery and bar gaseous dispensing is in the range of - kwh/ kg h , which results in - kg co /kg h with the current u.s. electricity grid mix. depending on the truck transportation and distribution (t&d) distance, and the truck payload of hydrogen, the ghg emissions associated with trucking hydrogen results in additional kg co /kg h for each miles t&d of kg payload of hydrogen. storage parameter units ultimate charging / discharging rates: • system fill time min - - - • minimum full flow rate (e.g., . g/s target for kw rated fuel cell power) (g/s)/kw . . . • average flow rate (g/s)/kw . . . • start time to full flow ( °c) s • start time to full flow (- °c) s • transient response at operating temperature %– % and %– % (based on full flow rate) s . . . charging / discharging rates: • system fill time: consumers expect to refuel a vehicle quickly and conveniently, especially on extended trips. the filling target is designed to parallel current customer experience. currently, gasoline vehicles are filled in approximately to minutes, with small vehicles taking less time than large ones. based on the expected efficiency of fcevs, approximately to kg of hydrogen will be needed for light-duty vehicles. this target will achieve near parity with current gasoline filling times. for a comprehensive comparison of fill time, the storage system should comply with the performance in sae j , the fueling protocol for light-duty gaseous hydrogen surface vehicles (http://standards.sae.org/j _ /). the units are minutes. note: the fill time involves not only delivery of the hydrogen to the storage system, but also any potential heat/mass transfer and/or kinetic factors associated with a particular storage system design. thus all factors must be considered especially when scaling small prototype systems to determine fill time. • minimum full flow rate: this target is a measure of the maximum flow rate of hydrogen https://greet.es.anl.gov/ http://standards.sae.org/j _ / required by the fuel cell system to achieve the desired vehicle performance. it is based on an average midsize light duty fuel cell vehicle, which typically has a power plant of about kw and maximum fuel flow from the epa us aggressive drive cycle. this is not a continuous flow target since the vehicle would not accelerate through an entire tank of fuel although it might be called upon to tow a large, heavy trailer up an -mile grade, such as is found on interstate near baker, california. however, because fuel cell efficiency is poorest at full load, while ices are at or near their highest efficiency at full load, fcevs may require higher full flow rates than this minimum to be competitive with ices. finally, this target is intended to indicate the potential for scalability for the hydrogen storage technology and thus the target is in units of mass/time normalized to fuel cell system rated power. • average flow rate: while the minimum full flow rate noted above defines the requirements for the storage system to supply hydrogen to the fuel cell system at peak load, it is also understood that an fcev will not be operated at peak load through an entire tank of fuel. as described for the minimum full flow, an average midsize light duty fuel cell vehicle with a typically power plant of about kw rated power was assumed for this target. this target is based on the average flow rate of hydrogen required by the fuel cell system for the epa us aggressive drive cycle although it is still not expected that the flow demand will be continuous at this average flow rate value. for potential for scalability for the hydrogen storage technology, the target is in units of mass/time normalized to fuel cell system rated power. • start time to full-flow ( °c): the vehicle may be able to start based on hydrogen in the lines, but to maintain adequate function without the need for a second energy storage medium (e.g. batteries), full flow must be available almost instantly. customers are currently accustomed to sub-second start times and full power available on demand, any time after the key is released. the target cold start-up time to achieve % rated power for the complete fuel cell system at °c ambient temperature is seconds. the storage system targets for start time to full-flow are set to meet the overall fuel cell system needs. in addition, the storage system must provide some flow to the fuel cell system within % of the time target for full-flow. the units for this target are seconds after start. note: this doesn’t mean that the entire storage system must start in seconds; only that it is capable of delivering fuel at maximum flow if requested. a moderate pressure buffer could serve to lengthen the true start up time. in that case, the mass and volume of the buffer would then need to be included within the system mass and volume. • start time to full-flow (- °c): see start time at °c for background explanation. the longer times reflect current customer expectation that in cold weather starting is more difficult. it is important to note that batteries are at their worst power capabilities at very low temperature. if a battery assist were contemplated, the battery system would likely have to be sized based on this starting condition, and thus would be rather large. this is why it has been desirable to avoid batteries for cold start if possible, unless sizing issues can be resolved. the target cold start-up time to achieve % rated power for the complete fuel cell system at - °c is seconds. consistent with the above target, some flow will be required to the fuel cell system within % of the full-flow target time. given the possibility that some hydrogen may be used to assist with cold start of the fuel cell system, the storage system is set to achieve full-flow within % of the start time for the fuel cell system. units are in seconds. • transient response %- % and %- % based on full flow rate: transient response is one of the greatest challenges a vehicle powertrain faces. the storage system must provide fuel to meet the needs of the fuel cell system to deliver adequate power and a suitable driving experience. therefore, the transient response must meet the fuel cell system requirement of . second ( and targets). the transient response is not necessarily symmetric. the to % transient target is to meet the demand of the fuel cell during acceleration. the to % transient reflects that the vehicle may need to stop using hydrogen almost instantly (e.g. safety shut-off) and the fuel supply must stop quickly enough to avoid over-pressuring any part of the system. this parameter impacts performance, fuel cell durability, and vehicle control. the units are seconds to change between % flow and % flow, or % flow and no flow. storage parameter units ultimate fuel quality (h from storage): % h meet or exceed sae j • fuel quality: hydrogen must be relatively pure going to the fuel cell system or else vehicle efficiency and performance will be degraded. the fuel quality from the hydrogen storage system must maintain or exceed the levels specified in sae j (http://standards.sae.org/j _ /). the levels of constituents in sae j were determined by experimental testing representative fuel cells with impurities. as indicated in sae j , even inert impurities can degrade performance by progressively diluting the hydrogen in the fuel cell system, resulting in a higher necessitating of venting from the fuel cell anode. other impurities react directly with the fuel cell catalyst resulting in immediate or long-term damage. the sae j fuel quality standard is the same requirement for the hydrogen delivered from the fueling station into the storage system. in other words, the hydrogen output from the storage system should not add significant contaminants beyond the fuel cell quality targets in sae j and iso specification iso/pdts - . it is also assumed that impurities from the hydrogen source do not degrade storage system performance. storage parameter units ultimate dormancy: • dormancy time target (minimum until first release from initial % usable capacity) • boil-off loss target (max reduction from initial % usable capacity after days) days % dormancy: • dormancy time target: this target protects against loss of driving range after extended periods of vehicle at rest (e.g., parking during a vacation). the dormancy period is especially relevant for hydrogen systems that operate at low temperatures. as the temperature in the tank increases, the pressure increases to the point that it needs to be released due to exceeding the maximum pressure rating of the tank. the period of time prior to this release (or boil-off point) is defined as the dormancy time. fuel cell vehicles purchased by typical consumers expect to have the same amount of fuel in their tank after extended parking, similar to gasoline vehicles today. for , the dormancy time target of days from initial % usable capacity was selected based on a typical period of time that a vehicle would be parked at the airport for a vacation. the % usable capacity qualifier was based on the consideration that the vehicle is unlikely to be parked immediately after a fueling event. the dormancy time target was extended for days at the same peak capacity to accommodate a two week vacation that a vehicle would be parked. the http://standards.sae.org/j _ / evaluation of the dormancy time should be conducted at the high ambient soak temperature which is assumed to be ºc for this target assessment. it should be noted that this is not the maximum ambient temperature although diurnal cycles reduce the average exposure temperature over a period of days. for most low temperature storage systems, the peak capacity condition will be the worst case for dormancy although lower states of charges should also be considered. the units for this target are in days. • boil-off loss target: this target is based on the desire to have minimal perceptible loss of driving range after the dormancy time is exceeded. as stated above, hydrogen systems with low storage temperatures experience heat loss that increases pressure and eventually requires hydrogen release or boil-off to avoid exceeding the maximum rated tank pressure. if the hydrogen released is not vented to the atmosphere, but used for other purposes (e.g., converted via a catalytic reactor or other uses) instead, then this additional balance of plant must be included as part of the storage system. the target is indicated as a % maximum capacity loss from the initial state of the tank over a day period of time. it is assumed that this capacity loss would not be notable to the average consumer and the days assumes a maximum time a vehicle would be at rest in normal operation. this target protects all storage system capacities equally and at all state of charge conditions. as specified for dormancy, the initial capacity condition is % of the rated usable capacity and the ambient soak temperature should be º c for this target assessment. for most low temperature storage systems, the peak capacity condition will be the worst case for boil-off loss although lower states of charges should be considered. storage parameter units ultimate environmental health & safety: • permeation & leakage - • meet or exceed sae j for system safety • meet or exceed applicable standards • conduct and evaluate failure analysis • toxicity - • safety - environmental, health & safety: • permeation & leakage: these targets are of great importance because they deal with protecting the health and well-being of individuals in contact with the storage system. the permeation and leak target are defined in sae j for the entire storage system, rather than per component or storage material. a system integrator or oem could cascade the system leakage targets to various elements with the system as necessary. permeation and leakage are differentiated from hydrogen release and boil-off loss in that hydrogen leakage leaves the storage system in an unintended manner while boil-off should be controlled and transformed into another species (e.g. water, via catalytic oxidation in a vent line). permeation and leakage thus pertains to the possibility of generating a combustible hydrogen-air mixture outside the storage tank. • toxicity: toxicity covers the possibility of consumer exposure to the storage material in normal, or abnormal conditions, plus worker exposure during manufacture and assembly. these types of toxicity criteria are generally regulated by applicable government standards. materials with a known hazardous risk potential shall be avoided. for example, the epa’s toxic substances control act chemical substance inventory (tsca inventory) and u.s. department of labor occupational safety and health administration (ohsha) can be used as references. • safety: safety covers all the typical safety statutes including certification and operation of vehicles, manufacture, transport, dispensing of fuel, and end of life issues. in each of these categories, compliance with federal standards and potentially state and local standards will be required. the onboard storage systems must comply with applicable standards for vehicular fuel systems including but not limited to sae j and the united nations global technical regulation no. (hydrogen and fuel cell vehicles). these standards include the minimum level of testing to determine the robustness of these hydrogen storage systems including hydraulic/pneumatic durability, burst, pressure cycle life, bonfire, chemical resistance, drop, penetration, environmental, and vehicle crash impact testing. the hydrogen storage system design must account for the requirements in these standards along with the applicable international standards in the nations that the vehicle will be deployed. for certain countries, the storage system and high pressure components require certification by a specified regulatory organization prior to on-road usage. sae j , j , j , j , and j (http://standards.sae.org/) provide the necessary references for vehicle and fueling interface standards. csa and iso also provide standards for safety guidance along with component certification standards. for storage system technologies (e.g. material-based) not specifically addressed in these standards, the intent of these safety requirements still must be applied to the design with appropriate engineering rationale and documentation until the incorporation into the standards. beyond regulated standards, hydrogen storage system developers should utilize automotive failure analysis tools such as failure mode and effects analysis (per sae j ) to identify and evaluate unique potential safety failure modes associated with their system. for example, metal hydrides are known to expand with absorption and can add strains to the storage tank, which should be included in the durability and safety testing as a potential failure mode in addition to the industry codes and standards. http://standards.sae.org/ 	 . background 	 . target table 	 . summary of new / revised targets 	 . assumptions 	 . detailed breakdown of the individual targets slavic review matical programming and tolerances in planning," economic computation and economic cybernetics studies and research [bucharest], , no. , pp. - ). this treatise offers an abstract framework to contain the diverse realities of the economic systems around us. the challenge now is to fill the intervening space, work- ing up from empirical detail and down from strict theory, to build a tested body of understanding. contributions to the effort may well appear in the new journal of com- parative economics whose editor, not surprisingly, is john michael montias. holland h u n t e r haverford college t r e n d s in t h e s o v i e t o i l a n d gas i n d u s t r y . by robert w. camp- bell. a resources for the future book. baltimore and london: the johns hop- kins university press, . xvi, pp. tables. figures. $ . . this compact, succinct little book is a useful companion to the author's economics of soviet oil and gas ( ). it admirably fulfills the stated intentions of updating the data base of the earlier work and reviewing the most important developments since . separate chapters deal with soviet energy policy, exploration, drilling, oil pro- duction, oil transport, oil refining, the gas industry, the economic reform in oil and gas, and soviet participation in world energy markets (as buyer and seller). in cogent summaries that bracket the more detailed discussion, professor campbell argues that soviet oil and gas planners now face problems different from those of the s and s, and that their success in dealing with these problems will determine both the level and structure of future soviet energy development. as usual, careful scholarship routs glib generalizations—for example, the undue pessimism about a soviet "energy crisis," and the undue optimism that the u s s r can bail the west out of its own energy crisis with massive energy exports. professor campbell attributes many of the problems soviet energy planners face to difficulties in meeting technological challenges—in drilling, oil refining, pipeline construction and operation, and the production of both oil and gas. this line of argu- ment is backed up by a wealth of technical detail. insightful (if tantalizingly brief) discussions deal with refinery mixes and product quality, the utilization of natural gas, the export of crude oil versus refined products, and planning methods (especially the attempts to apply optimizing models). in view of the apparent space constraints, soviet oil purchases in the middle east receive overmuch attention, with perhaps the least satisfying results. (arms sales and comecon debt instruments are stressed, to the relative neglect of the desire to minimize transport costs, given fixed commitments to communist allies—to the reviewer, the best explanation of those purchases.) unfortu- nate publication delays have left the data series two or three years out of date, in a situation subject to rapid change. not to carp, however—this is a valuable book for serious students of soviet energy policy and more general readers alike. a r t h u r w. w r i g h t purdue university t h e c l i m a t e s o f t h e s o v i e t u n i o n . by paul e. lydolph. world survey of climatology, vol. . amsterdam and new york: elsevier scientific publishing company, . xii, pp. illus. dfl. . $ . . dr. lydolph has performed a valuable and long overdue service in compiling a com- prehensive reference on climatic factors in the soviet union. his stated intent "is to present general climatic information that can be used as a basis for other studies which reviews deal in depth with applied climatology and climatic change." i feel that he has accom- plished his goal. approximately half of the book consists of maps and charts which cover a diverse range of subjects from the general locations of weather fronts to mean annual scattered radiation on a horizontal surface. where possible, dr. lydolph has presented varia- bility and chance of occurrence of phenomena to give a depth of understanding that the average values cannot give by themselves. these charts and maps contain nearly all the information that readers familiar with the subject need to know. most of the figures are collected from a large number of soviet sources, some of which are not widely circulated. the collection and organization of the figures themselves make the book worthwhile, not only to climatologists but to economists, political scientists, and agronomists who deal with events controlled by and related to climate. the first half of the book consists of detailed descriptions of regional synoptic climatology. dr. lydolph has divided the soviet union into five broad regions: euro- pean ussr and western siberia, eastern siberia, the far east, central asia, and the caucasus. these chapters suffer at times from tedious descriptions of data already presented in charts and maps. although the generalized descriptions, which are most useful to readers who are unfamiliar with the subject matter, are presented clearly and concisely in these same chapters, they are not separated from the more detailed descrip- tions. the result is that this portion of the book is sometimes difficult to follow. the second half of the book describes major climatic factors for the entire soviet union. heat, moisture, and wind, as well as climate description and classification schemes, are treated separately. in these chapters the text complements the many ex- cellent figures and provides one of the best overviews of the factors influencing soviet climate that i have seen. monthly climate data for soviet stations are included as an appendix. the spatial coverage of these stations is excellent, providing a small, homogeneous data base that can be used by the reader who requires analysis in greater depth. russell a. ambroziak central intelligence agency cordon s a n i t a i r e or b a r r i s r e d e l ' e s t ? : t h e e m e r g e n c e o f t h e n e w f r e n c h e a s t e r n e u r o p e a n a l l i a n c e p o l i c y - . by kalervo hovi. turun yliopiston julkaisuja, annales universitatis turkuensis, series b, vol. . turku, finland: turun yliopisto, . pp. paper. one of the outstanding merits of this monograph by historian kalervo hovi is its utilization of many previously unavailable archival documents. the author collected data for the volume in the archives of more than ten countries. the material from the french archives is especially significant, because it only recently was made acces- sible to researchers. in addition to his archival research, the author takes into account the literature on the subject to date. this enables him to give a more complex and more diversified picture than those authors who have relied chiefly on english and american sources when writing about the new federal policy of france. hovi's book is the first historical work to so widely describe france's eastern policy. it analyzes the objectives of the policy and summarizes its changes and the reasons for the changes. in the introduction the author notes the importance of the subject, summarizes the findings of previous researchers, and refers to the limitations imposed on them by the inaccessibility of the french sources. this lack of original source material generally caused historical works on the eastern policy of france to follow one of the two traditional interpretations: the "barriere de test" or the "cordon sanitaire." hovi refers to the origins of these concepts, analyzes their meanings, and discusses their wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ s jra .. lessons from the ghost of salaryman past: the global costs of the breadwinner imaginary robin m. leblanc about the time of the one-year anniversary of the march tōhoku earth-quake and tsunami, a conversation about the politics of nuclear power started up among japanologists, mostly political scientists, on a listserv i read daily. the original discussion emerged from the question of whether japanese political leaders would push for restarting a number of the offline nuclear power plants across the country in order to cover expected gaps in japan’s electricity supply. at first the debate’s participants took up the countervailing pressures japanese policymakers face: the need to provide affordable power to japanese companies in order to spur economic recovery, the inevitable increase in greenhouse gas emissions that would be produced by a shift from nuclear to fossil fuels, the polling data suggesting an overwhelming majority of japanese citizens are opposed to restarting the plants (mainichi shinbun ). then the listserv debate broke away from scholarly assessments of the electoral and policy dilem- mas faced by the ruling democratic party into thinly veiled arguments between proponents and opponents of nuclear power. some assertions were made about the nuclear power “phobia” and “emotional” opposition of those who, it was suggested, do not understand the science of it, and a debate commenced over the question of how many people the chernobyl accident of had really killed. finally, the listserv participants settled into an examination of which source of power, coal or nuclear, takes the most lives, when all the risks of coal extraction, air pollution, and such are matched against the likely frequency and scope of dis- asters of the sort that happened in fukushima. soon after this, the online discus- sion fizzled out. the conversation had, at any rate, lost its tone of collegiality, and the difficulty, especially for social scientists, of thinking through the probabilities associated with natural events on the scale of the tōhoku earthquake and tsunami made the calculations of potential coal or nuclear casualties difficult to perform. yet although i had never joined the debate myself, i had trouble moving my mind away from it. something about it felt wrong to me, but i could not quite put my finger on what bothered me. robin m. leblanc (leblancr@wlu.edu) is cannan professor of politics at washington and lee university. the journal of asian studies vol. , no. (november) : – . © the association for asian studies, inc., doi: . /s at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core when i did fieldwork in a citizens’ movement against a nuclear power plant, in , long before the triple disasters of – , i had several times heard one of the group’s leaders, baba-san, draw comparisons between coal and nuclear power. rather than trying to sort out claims about which method of power gen- eration was more dangerous, baba was trying to draw my attention to the way advocates for all kinds of power generation silenced opponents by insisting upon the inevitability of individuals’ sacrifices in return for the goods dependent upon electricity. baba talked angrily about what he described as the countless lives sacrificed (giseisha) in prewar japanese coal production. he then compared the lives lost to coal to the sacrifices asked of japanese men who gave their lives on the battlefronts of world war ii. baba further insisted that the same logic that had been employed to justify the loss of men in dangerous coal mines or useless, fatal battles had been used in the postwar era to push men of his own generation into punishing hours of work on the factory floors of japan’s economic “miracle.” baba expressed despite for the entire idea of noble sacrifice romanticized as manly duty; he said he hated the very word “gisei.” he repeatedly pointed out that actual sacrifices were never evenly distributed among people. the powerful men who praised a masculine spirit of self-effacement were more likely to be the beneficiaries of others’ sacrifices than to bear loss themselves, he said. as i recounted in the book i later wrote, despite the fact that he described himself as a man who could work for “all he was worth,” baba also said he hated words such as “kinbensa” (diligence) and “dōryoku” (effort), which are attached to the image of japan’s model middle-class “salaryman” worker (leblanc , ). baba said that praise of diligence and effort was only an attempt to get ordin- ary people, pressed simply to make a living, to give themselves up wholly into service of elites’ desires to be ever richer and more powerful; new riches for a community did not necessarily mean better lives for all community members. according to baba, at some point, a community must decide that it has enough, materially, to live well. policymakers’, power company executives’, and local nuclear power plant supporters’ insistence that baba’s town get over its “regional ego” and take on the potential risks of a nuclear power plant were, as baba told it, simply attempts to get citizens to give into the logic and associated sacrifices required in the pursuit of unending growth. interestingly, the plant supporters whom baba opposed also drew connec- tions between the sacrifices demanded of coalminers, soldiers, and salarymen and the reasons why the town ought to accept a nuclear power plant. they dif- fered with baba only in their conviction that the risks and sacrifices were valuable and honorable. localities must be willing to do their duty for the nation, one pro- nuclear interviewee told me. nuclear power opponents are likely young mothers who do not really understand the issues, another suggested, implying that men would (or should) know better. nuclear power was, plant supporters said on many occasions, necessary in resource-starved japan to support the factories robin m. leblanc at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core that provided the jobs for japan’s salarymen. in turn, the salarymen’s work was essential to their families’ well-being and to japan’s survival in a viciously com- petitive global arena. a local referendum had documented the citizens’ overwhelming opposition to a nuclear power plant a few years before i began my fieldwork. the central issue in the election i observed while conducting my fieldwork was whether the referendum’s result would be enforced through the local government’s offi- cial resistance to the plant plan or whether a strong pro-plant majority in the local assembly would be able to push the project through, despite voter opposi- tion. although the plant was clearly the dominant issue in the election, nearly every nuclear power-supporting candidate avoided mentioning nuclear power in his campaign literature, instead describing himself as “for economic revitaliza- tion.” at the time, the use of the term “economic revitalization” struck me as an unethical and slippery way to avoid a public admission of support for the hugely unpopular project. however, the pro-nuclear candidates might simply have insisted that econ- omic revitalization was their real goal all along, the nuclear power plant only one on a long list of hard choices necessary to achieve that revitalization. i suspect if i went back to them today, even after the meltdown of the plants at fukushima, many of the nuclear power proponents, like many of my listserv colleagues, would ask me to consider what other choices japan really has. how else, they would want to know, will the local and national economies be able to grow again, to provide young men the jobs they need to start families, to buy homes, to revitalize a japan where no one is having babies? they would not be alone. in at least one town where a nuclear power plant has been shut down in the wake of – , citizens openly express worry about how their economy can possibly thrive without it (kyōdō ). i had these conversations more than a decade before the – disasters, and perhaps that is why i was uneasy remaining silent in the face of my listserv col- leagues’ debate. i felt i must have something relevant to bring to the discussion, but while my colleagues argued about whether the risks posed by plant design, japan’s geology, or weak regulatory structures could have been, should have been, or would eventually be surmounted, i was hung up on a different problem. i was stuck gnawing at the suggestion baba made, more than a decade before – , that the logic of “hard choices” in the pro-nuclear power rhetoric was somehow akin to the logic of sacrifice in war, that the mobilization of dedicated salarymen and that of soldiers was not so different, and i could not figure out how to make that point in the context of the argument among my scho- larly colleagues. an important part of why baba disliked the rhetoric of the nuclear power supporters was that he thought it unfairly invoked notions of masculine duty and courage to make it difficult for men who wanted to think of themselves as good men to stand in opposition to it. the tone of the listserv discussion lessons from the ghost of salaryman past at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core participants and the traded accusations of phobia and unrealistic optimism into which the debate so quickly dissolved reminded me of baba’s complaint about the valorization of manly sacrifice. at some point, it seemed to me that it was not any particular answer to the complicated technological, sociological, econ- omic, political, or ethical questions of japan’s situation that was at stake in the debate, but rather a kind of intellectual manhood. yet, i could not simply write off the online argument because it was one among experts, some of whom might well influence leaders in japan and elsewhere on these issues, and because i heard similar debates unfold in conferences, over dinner tables i shared with colleagues, and among my students. whether among the japanese citizenry or in the many post-fukushima debates i have witnessed among my fellow social scientists, the rules of manhood tend to constrain critical thinking about nuclear power in japan today, whether the individuals engaged in the discussion are male or not. doubt- less, that is in part because historically a culture of masculinity has helped to shape the cultures of academic and public discourse. but, more importantly, manhood matters because behind the nuclear power debate lurks an unarticu- lated but framing concern with whether the japanese economy will allow workers (breadwinners) to feed their families. the breadwinner, habitually conceived of as the japanese salaryman, is gendered male. this salaryman- breadwinner imaginary pushes the power-generation conversation back and forth between the polarizing dangers of nuclear power and economic decline. i think one reason that, at each pole of the debate, interlocutors summon up terms of critique that imply failed manhood, such as unwarranted idealism or unreasonable anxiety, is that, as they battle back their opponents’ claims, they are thinking empathetically from a breadwinner’s (male) position. this bipolar debate is not completely without sense. breadwinners do want and need to feed their families. but because the salaryman-breadwinner image is freighted with the contents of other symbol systems—japan’s modernity, its fit with the west, its place in a global economy frequently conceived within and outside of japan as a vicious competition among nation-states—any debate that has a ghost of salaryman lurking in its corners also becomes strangely limited to a worldview in which nation-states are the appropriate object of analysis and in which the global economy is conceived of primarily in terms of interstate competition. my point is not to theorize economies or economic discourse generally. i am not about to argue that it is wrong to take up economic policy questions with a view to their impact on the well-being of actual working people and those who depend upon them. i am not asking us to look at men’s dominance over women. i am not trying to make an argument for or against nuclear power. i am not trying to offer japan a path out of the – crises. the loss and displace- ment of tens of thousands of people in the wake of the triple disasters is an unspeakable tragedy, most of which, horribly, inescapably, must be managed robin m. leblanc at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core on a one-by-one basis as individuals search out whatever it might be that will allow them to live on in some way despite the people and things that have been taken from them. the other crises—of political leadership, of energy pro- duction, of the economy, of the environment, of the growing numbers of under- and unemployed youth, of hope—already existed. right now i want to focus on the less-noticed constraints that ideas about manhood place on individuals’ assumptions about what men’s and governments’ choices are. what i want to do to is to provoke my readers into considering how fre- quently, in debates among scholars and laypeople of the late capitalist countries, assertions about what is necessary or inevitable for a nation rely, as baba insisted was true about nuclear power debates, on unspoken assumptions about what is required to sustain a particular notion of manhood. in late capitalist countries, we still count on individual workers (breadwinners) to obtain and distribute the resources that sustain families, communities, and the opportunities and joys of life, despite the many ways in which the model fails in actuality. japan’s workforce is so highly sex-segregated that my claim that the breadwinner is imagined as a male salaryman is hardly controversial, but research by gender scholars around the globe suggests that, even with women’s greater participation in the workforces of other rich countries, the imagined model worker is still a man, and thus is a construct likely to bring with it constraints of manhood similar to those we see in japan. i want us to think about what it might be costing us to enter conversations about issues such as the public risks of nuclear power generation with unexa- mined presumptions about who might be the “regular” working people we are imagining justify our position. i want us to think through japan’s situation, and then i hope we will work together to determine what japan’s example might reveal more generally about what are or are not the relevant boundaries on policy debates. in the case of japan’s current energy crisis debate, and in previous versions of it, the presumed needs of the model, male, white-collar breadwinner, or “salary- man,” conception of the “regular person” has loomed large. if we do not dig down into the imagined masculinity of the breadwinner in the framework of discus- sions, such as the one about nuclear power, taking place among students of japan right now, we cannot ask all the questions we should about how late the same might be true in many countries that we could not include among the group i here call “rich” nations, but for the sake of clarity in this short essay, i am sticking to the countries of europe, north america, and japan. perhaps south korea, singapore, or taiwan would fit as well, but they are very recent entrants to the “community” of wealthy nations. taiwan’s situation is further com- plicated by its ambiguous international status as not-fully-recognized nation-state. for evidence of how difficult it is to imagine women as family breadwinners even in the united states, which has a more fluid gendering of the work world than in japan, we need only consult a recent businessweek article about the identity challenges faced by men who have taken up child- care and housework to allow their wives’ careers to advance (hymowitz ). lessons from the ghost of salaryman past at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core capitalist societies are organized or about how the community of late capitalist nations works (or fails to do so), whether for us, for nations, or for humanity in general. we cannot really total up the costs of nuclear or coal-based power gen- eration or many other sorts of things we collectively do for and to our economies and societies. the salaryman as a soldier the salaryman, in a conservative business suit—with his “ to ” work hours, a commitment to his employer that won him the japanese soubriquet kaisha ningen or “company human,” and bowing solemnly as he gives and receives business cards—has come to seem quintessentially japanese. he is so well associ- ated with his nationality that he can be represented in american television and movies as if he is japan. but the truth is, the salaryman, as his derived- from-english name implies, has always represented japan’s engagement with the west. in fact, the salaryman is only one of the more recent imaginations of japanese manhood that has been constructed in a discursive community well aware of the global context of japan’s modern economy and politics. from at least the time of the iwakura mission, in which important pol- itical leaders toured the united states and europe in search of the means to place japan on an equal footing with the west’s encroaching imperialist nations, japa- nese policymakers and pundits have pressed their countrymen to meet standards of manhood believed essential for keeping japan abreast of competitors around the globe. whether they have relied on the version of boys depicted in the trans- lated american education texts used to develop japanese elementary school cur- ricula as early as the late nineteenth century, or the bearded, uniformed masculinity displayed in emperor meiji’s portrait carefully modeled on prussian military images, japanese notions of manhood have been persistently defined within a consciousness of what manhood has been taken to be in the powerful north atlantic countries (frühstück and walthall ; osa ; roden ; yamazaki ). even in contemporary self-help books, where readers see “post-racial” depictions of successful salarymen and get advice for how to negotiate dinners in paris, doing manhood right is inextricably linked to develop- ing “global savoir-faire” (frühstück and walthall , ). of course, indigen- ous traditions of masculinity have been similarly valued, but whether in response to or in defiance of western standards, according to military ideals or modern standards of economic competence, defining japanese manhood has been one means of securing japan’s place in the international system (mikanagi , – ). these days the japanese salaryman is sometimes seen as stubbornly resistant to the changes japanese firms need to make to compete in the dynamic global economy, but we should remember that until recently, both within and beyond robin m. leblanc at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core japan’s borders, the salaryman was seen as one reason why, only a few decades after ignominious defeat in world war ii, japan had become an economic force with which the west must reckon. in popular discourse, salarymen have often been referred to as kigyō no senshi (corporate warriors), and that reference is intended to imply not only service to company but also, because corporate “warriors” are assumed to be in the business of making japan economically powerful, service to nation. in the postwar era, the connection between salary- men and self-sacrificing service to company and country has been so strong that employers have invested in spiritual training courses for the salarymen; some employers have even looked directly to japan’s self-defense forces for train- ing models that emphasize patience and endurance under great stress (mikanagi , – ). in his now famous book japan as number one: lesson for america, sociologist ezra vogel pointed to the hard-working “company man” as one of the key reasons japan, a country “without natural resources,” had dealt with the challenges of postindustrial society with a success that “astounded” him (viii). according to vogel, japan’s model breadwinners prevented socially and economically destructive standoffs between employers and workers because of their “devotion to their company[ies]” ( ). through the employment scheme under which they worked, they delivered, relatively equally across society, the benefits of homeownership and modern conveniences, and, in doing this, they provided inspiration to the young ( , ). vogel ascribed the achievements of salarymen to the practice of corporate organization that made their choices of loyalty and hard work rational ones. [the japanese company] is successful not because of any mystical group loyalty embedded in the character of the japanese race but because it provides a sense of belonging and a sense of pride to workers, who believe their future is best served by the success of their company. the pride and stability that so many japanese have because a family member works in a large company helps stabilize the political process and set a tone for society at large. ( ) in the years since the publication of japan as number one, scholars have argued that other social structures, such as the labor force flexibility and unpaid care work provided by women, who were marginalized in the salaryman-focused cor- poration, helped to make this effective breadwinner model a possibility (see, e.g., brinton ; schoppa ). some have drawn attention to the fact that large groups of men have never neatly fit the salaryman role (roberson and suzuki ). as a number of gender scholars have noted recently, the “salaryman” identity of the middle-class, lifetime-employed corporate male breadwinner is, statisti- cally speaking, in decline. the commitment of corporations to hire workers lessons from the ghost of salaryman past at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core according to the salaryman model eroded over the past two decades of nearly stagnant economic growth. an increasingly large percentage of young men struggle to find positions in the workforce that approximate the salaryman status their fathers achieved (brinton ). far fewer men marry and become family breadwinners than was true a generation ago. moreover, the sal- aryman is not simply a difficult identity to perform; it is a far less valued identity. many young men simply do not aspire to be salarymen like those of their fathers’ generation. among young women it is fashionable to express despite for salary- men whom they imagine to be boorish, or, worse, chronically lecherous (bardsley ; horii and burgess ). tragically, even many salarymen themselves seem to be quite doubtful about who they are and what they represent. mature men’s suicide rates suddenly doubled in the economic crisis at the end of the s and have stayed high (national police agency ). vogel argued, i think quite accurately, in , that the salaryman’s work ethic and job stability were the heart of japan’s postwar social welfare mechan- ism. “even when japan’s growth far surpassed other countries and unemploy- ment was virtually nonexistent, the japanese employee sought workplaces that provided security and he exerted himself for his company, for public welfare was not a real alternative,” he said ( ). the private workplace now fails to provide this sort of stability for young people, but families have no clear alterna- tives to dependency upon the male breadwinner’s family wage. the breakdown of the salaryman path to household well-being has contributed to the rise of inequality and poverty in japan in recent years (brinton ; ōsawa ). although these days actual salarymen are ever more rare, no newly imagined model worker has taken the salaryman’s place. the ghost of the past salaryman is so central to the understanding of how japan’s late capitalism is supposed to work that replacing him with some new notion of who is “manning” the economy would mean a public admission that the national project of privatized self-sacrifice for the sake of the collective good is not working for some substan- tial portion of the population. un-cool biz the salaryman-breadwinner is still imagined as the model worker on whose shoulders the japanese economy rests, but the risky business of keeping japan going in a vicious global marketplace is often undertaken by someone else. no one embodies this truth better than the workers who manage the fukushima meltdown site. like self-effacing soldiers, they expose themselves to tremendous risk to do work that must be done for the good of the nation; but many also work only as temporary workers, part of the growing body of japanese men today who will never be recipients of the secure, esteemed jobs of real salarymen (jobin ). tellingly, although the fukushima temporary contract workers enact robin m. leblanc at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core the courage and display the work ethic that has long been associated with salary- man manliness, they get little attention in public discourse. instead, the crisis- related salaryman sacrifice that has received top billing is the “cool biz” campaign to change men’s work wardrobes so that office buildings can raise the temperature setting on air conditioners in order to conserve energy. cool biz began as an initiative of japan’s environment ministry in . men were encouraged to take off their ties and leave their suit jackets at home during summer months so that their employers could turn up the air conditioning temp- erature and conserve energy, but it was not until the summer of , when japan confronted a shortage in the energy supply caused by the shutdown of nuclear power plants in the wake of the – triple disasters, that cool biz really gathered steam. in , the campaign started in may, a month earlier than in the previous year, and it has expanded to include instructive fashion shows; “super cool biz,” a flamboyantly casual version prescribing “fun” cool clothing such as hawaiian shirts; fashion industry efforts to capitalize on new clothing trends; and various forms of official rhetoric urging clients and customers visiting cool biz work- places to be accepting of men’s casual state of dress. the international media have joined the chorus, and japanese cool biz is reported on around the globe. the cool biz campaign has many of the qualities of other weird stories that capture the attention of the japanese and foreign media, such as high school girls’ “compensated dates” with older men (leheny ). given the seriousness of japan’s energy crisis, a public uproar about a change in work wear seems like a silly distraction. however, what, at first glance, we might think could only be a trivial part of public debate about japan’s energy crisis—men’s work wear—is, when examined further, powerfully instructive about the way in which important contemporary discussions of resources and the economy are enmeshed with the preservation of certain notions of manhood. cool biz may seem to be a far cry from the manipulation of masculine duty that baba denounced more than a decade ago and quite different from the “man-up” standoff between proponents and opponents of nuclear energy with which i opened this essay. yet, in its see- mingly laughable elements, the growth of the cool biz campaign displays the importance of the salaryman imaginary to debates about how japan ought to respond to the crisis of - and helps us to understand why, unless we challenge that imaginary, those debates will remain dangerously constrained. why is it that, in the face of the immensity of the japanese energy crisis, the best leadership the government can provide is to suggest that men leave their ties and jackets at home? why is it that, in one of the most literate and peaceful democratic nations on earth, men in the most secure white-collar jobs cannot actually, “cool biz” was promoted by the government and elected officials for years, but it became an actual phenomenon only after – (warnock ). a quick google search of the term turns up an ever-growing world of cool biz imagery and related enterprises. lessons from the ghost of salaryman past at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core be relied upon to choose garments appropriate to the temperature conditions they must endure at work? the answers to these questions lie in the rich histori- cal and contemporary meaning of the western-style men’s business suits. the business suit is a marker of a japanese male breadwinner’s place in the country’s white-collar workplace, which, as vogel ( , ) pointed out, once produced the “pride and stability that so many japanese have because a family member works in a large company.” but perhaps even more important to the cool biz program, the business suit, with its associated and transnational connotation of masculine power, is also a marker of japanese men’s place in a globalized, techno- cratic, and masculine hierarchy that still “includes many remnants of colonial atti- tudes toward the developing world” (connell ). the large number of japanese men who go to work in suits is both the result of the particular japanese culture of the salaryman and yet globally legible as evi- dence of japan’s place as one of the “advanced countries” (senshin koku). surren- dering the suit under the pressures of japan’s limited energy resources, thus, is more than making a choice of which garment will be more comfortable in a sweaty office; it is also an unavoidable confrontation with japan’s limits in the global marketplace. if japan’s elite workers must dress as if they live in a country not yet developed enough to provide climate-controlled workspaces, then they may also have to ask themselves in what way japan really differs from lesser-developed asian nations that are not yet full members of the western, “advanced” democracies club. the cool biz campaign discourse, which equates the relinquishment of the necktie with national service, leaves in place the figure of the self-sacrificing sal- aryman as the symbol of the japanese economy, of regular people, of the spirit according to which the nation ought to buckle down to face the challenges ahead. the clothes of the salaryman might be changed, just as if he were a paper doll in the hands of a determined little girl. the salaryman’s symbolic cen- trality to making the whole project of buckling down intelligible to japan as a nation and of displaying—to japan and among the other countries with which japan competes for status—a japanese man’s capacity to do his duty is preserved. with the image of the salaryman sweating in an underlit office, japan is resource poor but rich in spirit. americans, bundled up all summer in their over-chilled work cubicles, still have lessons to learn. importantly, the cool biz business intensifies our focus on the needs of the breadwinners, who, depicted as sweating over their desks, trying awkwardly to make casual wear look professional, become again the protagonists of a noble women, whose jobs are generally less important and less secure than those of men and whose work wardrobes are much more diverse and frequently changing, seem to be less central to and are perhaps less in need of the cool biz campaign. the importance to domestic politics of securing status among the elite western nations and avoid- ing the stigma of backward or uncivilized the west has historically imposed on non-western countries is lucidly explained by ayşe zarakol ( ). robin m. leblanc at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core war against japan’s resource limitations, as they were in vogel’s japan as number one. the cool biz campaign praises sacrifice, but it also recasts “sacrifice” as something immensely more palatable than what those area residents or workers directly affected by the meltdown must endure. the courage required to go to work without a tie or to wear a tropical-style shirt to a meeting with a client is surely infinitely easier to muster than the courage required to set up a new life knowing one can never go home again or to take a very risky temporary job because the pay is good and steady work may not be in the offing again for a long time. the cool biz campaign functions also as a reminder that japan’s economy and thus japan’s earnest breadwinners are struggling desperately to get by without nuclear power and therefore highlights its essential contribution to the japanese economy. cool biz has the effect of cheerfully keeping the post- crisis debate constrained within the “potential nuclear accident” and “economic decline” poles while the diligent salarymen-protagonists, shorn of the ties, suit coats, and even white collars that had marked them as men who belong to the global elite, help us to decide which of those poles is scariest. when we consider the genesis of the salaryman-breadwinner-corporate warrior identity around which cool biz is focused, we must never forget that this manifestation of japanese masculinity has deep roots in japan’s self-conscious engagement with western traditions of masculinity over more than a century and a half. the suited breadwinner who requires a chilled office is not a weird japa- nese invention; the japanese salaryman imaginary is simply more self-consciously true to a masculine practice common throughout the developed world. the see- mingly ridiculous redirection of a public debate about energy needs and the costs of various methods of meeting them into a men’s fashion campaign points to the lingering power of the salaryman as japan’s model worker, even as actual salary- men—the loyal soldiers of equally loyal companies—fade into the past. this per- sistent ghost of a salaryman is costly for japanese society because the lingering salaryman ideal obscures the real need for new visions of what japan is or could be. this is true in areas of concern relatively distant from energy politics, such as the growth of inequality in the workforce or the way in which the calci- fication of the male model work image affects women, families, and the fertility rate. but perhaps more disturbing is the fact that, if we look carefully at who the salaryman was intended/assumed to be, we see that he is nothing other than an extraordinarily well developed model of the citizen-worker aspired to across the community of rich (mostly western) nations. what the salaryman means for the rest of us what bothers me about cool biz and the energy-versus-growth focus in post- crisis discussions about japan is the unconscious reliance on the notion that workers are soldiers in a nation’s economic war and that the generation of lessons from the ghost of salaryman past at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core power (and not just electricity) should also be considered from within that frame- work. the implicit frames slide too easily among levels of analysis. men become metaphors for the nation-state; the advantage of nation-state is conceived as if it were analogous to the protection of a breadwinner and all who are dependent upon him. then nation-states are imagined as independent entities, separate from other nation-states, just as the late-capitalist breadwinner is presumed to be his own welfare system. the focus on the effort of breadwinners to do what is necessary to keep their jobs—a focus on the obligations rather than the privi- leges that come with manhood—dampens our critical sense of the operations of power concealed in the idea of these obligations. seeing the earnest worker in the sweat-soaked shirt bent over his desk, we do not think to ask who he is and who—so many of the young, so many women, so many elsewhere—do not get to be him both in japan and around the world. seeing his plight (a real one) we do not consider that, trapped though he is by duties as a breadwinner, he also is a bearer of costly privilege, of a way of life una- vailable to many who provide resources for the systems to which he is obliged. sympathetic to the weight of his duties, we fail to ask if the world he represents can be possible much longer. understanding what the breadwinner needs, we see only the tradeoff between safety from nuclear risk and safety from economic decline. but that equation is far too narrowly conceived. we should be working with much bigger imaginations that stretch past the nation-state bound- aries in conversations about economic growth, that stretch past the necessity of economic growth itself, that stretch past a way of organizing work that served rich country breadwinners (when, uncomplainingly, they served it) to something new, more possible over the long haul, and more human. we smile condescendingly at japan’s men-who-have-given-up-suits as if the global community can actually afford for the real members of the rich nations’ club to keep cold offices in midsummer. we pretend like we do not know what the suits mean, as if there is no racial joke when japanese salarymen show up in a mad men episode. we do not say too much about the british petroleum oil disaster in the gulf of mexico. we do not pause the risk-versus-growth, “hard choices” conversation long enough to ask for whom, exactly, the choices are hardest. we do not ask what other choices we are ignor- ing. once we get stuck in a framework that owes debts to this sort of implicit vision, we consider japan’s energy policy decisions as if japan alone, and not humanity in general, is resource poor, as if japan alone, and not also the rest of us, must weigh the environmental costs of burning fossil fuels against those of radiation pouring into the air or sea, and as if we have nothing, as a global com- munity, to gain or lose if some of japan’s rural people are persuaded to risk death or permanent displacement from their homes in order produce “clean” nuclear energy. i want to provoke my readers into placing such debates in a bigger frame, into considering the possibility that baba is right, that an insufficiently discussed robin m. leblanc at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core notion of manly self-sacrifice delimits the boundaries of public imagination about the definition of and solution to the fundamental puzzles of well-being, not just in japan, but in many countries. the salaryman, whose signature suit represents a vision of energy plenty that may be forever gone, is not japan’s mistake, not japan’s special problem, but rather evidence of the fullness with which the late- capitalist liberal democratic project has inhabited japan. in the rich democracies, we are proud to have (at least in our dealings with each other) traded guns and camouflage for business suits and entrepreneurial initiative. however, for many of us, including scholars talking as scholars, the global economy is still a war, and our proud financiers, engineers, and men of commerce are still imagined to be men and still assumed to be soldiers. it is no wonder that my scholarly colleagues email-shout about power-production phobias and alternative counts of the coal and nuclear dead around the world. in war, a steady source of power is essential, even if lives must be given to gain it. twisted like a prism in the light, this economic war logic can come to look just shy of insane. economic expansion (still deadly and, beyond the rich countries’ borders, still involving lots of their soldiers and guns) has replaced territorial expansion as the goal of the men at the front. meanwhile the public seems to demand even less justification for it than they did of the brutal projects of imperi- alism their countries pursued in the previous two centuries. that is because this war does not rely on patriotic support of a national army, which when it takes a man too long from his private life may become intolerable for him and his loved ones, but instead rests on the private commitment from and care for millions upon millions, perhaps billions, of mercenaries, working people imagined as typical male breadwinners who need jobs because others depend on them. the japanese salaryman is perhaps the most intensified vision of that breadwinner-soldier in all of the rich world, even now when he is but a ghost of his former self. nonetheless, i think if we look around we will see he is not alone. other ghostly breadwinner-soldier models exist. they, too, are armies of individuals making do with jobs whose terms they do not define, accepting hard choices, doing their duty for home and nation, not thinking it is time to demand peace, or even anything else. list of references bardsley, jan. . “the oyaji gets a makeover: guides for japanese salarymen in the new millenium.” in manners and mischief: gender, power, and etiquette in japan, eds. jan bardsley and laura miller. berkeley: university of california press. brinton, mary c. . women and the economic miracle: gender and work in postwar japan. berkeley: university of california press. lessons from the ghost of salaryman past at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core ——. . lost in transition: youth, work, and instability in postindustrial japan. new york: cambridge university press. connell, r. w. . “globalization, imperialism, and masculinities.” in handbook of studies on men & masculinities, eds. michael s. kimmel, jeff hearn, and r. w. connell. thousand oaks, calif.: sage publications. frÜhstÜck, sabine, and anne walthall. . recreating japanese men. berkeley: uni- versity of california press. horii, mitsutoshi, and adam burgess. . “constructing sexual risk: ‘chikan’, col- lapsing male authority and the emergence of women-only train carriages in japan.” health, risk & society ( ): – . hymowitz, carol. . “behind every great woman.” bloomberg businessweek, january . http://www.businessweek.com/magazine/behind-every-great-woman- .html#p (accessed june , ). jobin, paul. . “dying for tepco? fukushima’s nuclear contract workers.” the asia-pacific journal: japan focus ( / ). http://www.japanfocus.org/-paul-jobin/ (accessed on july , ). kyōdō. . “hamaoka plant halt leaves locals in economic limbo.” the japan times, may . www.japantimes.co.jp/print/nn f .html (accessed may , ). leblanc, robin m. . the art of the gut: manhood, power, and ethics in japanese politics. berkeley: university of california press. leheny, david richard. . think global, fear local: sex, violence, and anxiety in contemporary japan. ithaca, n.y.: cornell university press. mainichi shinbun. . “honsha yoron chōsa: ōi genpatsu no saikadō ‘hantai’ ha %” [a mainichi public opinion poll: % oppose restarting ōi nuclear power plant]. may . http://mainichi.jp/select/news/ k m c.html (accessed june , ). mikanagi, yumiko. . masculinity & japan’s foreign relations. boulder, colo.: firstforumpress. national police agency, government of japan. . “heisei nenjū ni okeru jisatsu no jōkyō” [data for suicides in ]. http://www.npa.go.jp/toukei/index.htm (accessed may , ). osa shizue. . “tenshi no jendā” [the gender of the emperor]. in kyōdō kenkyū dansei ron [cooperative research in masculinities theory], eds. y. nishikawa and m. ogino. kyoto: jimbun shoin. ōsawa, mari. . “saibunpai no jendā baiasu ga hinkon wo fukameteiru” [gender bias in redistribution deepens poverty]. gakujutsu no dōkō ( ): – . http://dx.doi. org/ . /tits. . _ (accessed june , ). roberson, james, and nobue suzuki. . men and masculinities in contemporary japan: dislocating the salaryman doxa. new york: routledge. roden, donald. . “thoughts on the early meiji gentleman.” in gendering modern japanese history, eds. barbara molony and kathleen uno. cambridge, mass.: harvard university asia center. schoppa, leonard. . race for the exits: the unraveling of japan’s system of social protection. ithaca, n.y.: cornell university press. vogel, ezra. . japan as number one: lessons for america. cambridge, mass.: harvard university press. warnock, eleanor. . “it’s baaack! the return of (super?) cool biz.” wall street journal, april . robin m. leblanc at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core yamazaki, hiroshi. . “kindai dansei no tanjō” [the birth of the modern man]. in nihon no otoko ha doko kara kite, doko e yuku no ka [japanese men: where they came from, where they are heading], eds. h. asai and s. itō. tokyo: jūgetsusha. zarakol, ayŞe. . “deviance, abnormality and stigmatization in international relations.” paper presented at the annual meeting of the international studies association, san diego, ca, april – . lessons from the ghost of salaryman past at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core dec _preslet.qxp letter from the president mrs bulletin • volume • december the original manhattan project was conceived in fear, and executed in haste. it accomplished stunning technical achieve- ments in an astoundingly short time and unquestionably changed the world—for both good and evil. many argue that the looming energy crisis calls for a global thrust of similar urgency, sacrifice, and innovation, and that our generation will ultimately be defined by how we live up to this challenge. a number of scientists have recently highlighted the emerging energy gap that richard e. smalley called the terawatt challenge (www.mrs.org/publications/ bulletin/ /jun/). nate lewis provides an exceptionally erudite and clear exposi- tion on his web site (www.its.caltech.edu/ ~mmrc/nsl/energy.html), and the u.s. department of energy provides excellent references for energy usage (www.eia.doe. gov/emeu/aer/contents.html) as well as the report on “basic research needs for solar energy utilization” (www.sc.doe. gov/bes/reports/files/seu_rpt.pdf). the gap arises from a convergence of an escalating demand for energy and a cata- strophic accumulation of atmospheric carbon. we know that the wests’s sense- less profligacy with energy has accumulat- ed damaging levels of co that are caus- ing global warming on a scale not seen in ice-core records. we know that if we stopped producing co today, it would take years for atmospheric co to return to s’ levels. we expect (and hope) that over the next two decades million people in india and china will emerge from poverty to become new con- sumers. and we know that it takes energy to make people rich and that rich people burn more energy. we know that the gap between our current energy supplies and the unmet needs of the next years is in the region of – tw. but we do not know of a way to generate this kind of energy economically without making even more co . this forms the basis of a global challenge that dwarfs that of the manhattan project, one which should be met by an integrated global technical collaboration on a scale never before seen. the scale of the energy gap seems to dic- tate breakthroughs on both the supply and demand side. the demand side is where most opportunities have been squandered, not only, but especially, in the united states. (what will we tell our grandchil- dren when they ask us what in heaven’s name we did with all that oil? you did what? you did mpg??) historically, the rate at which we burn energy to get richer has improved somewhat over time. this should be improved much faster and much more steeply. technologically, there are huge gains to be made. lighting alone represents % of u.s. electricity consump- tion, and improved materials such as ingan offer every prospect of vastly reducing this number. heating and cooling are another large component of overall energy use, and again, thermal and radia- tion management through materials offers enormous prospects for improvement. transportation is perhaps especially galling in that the gains are there for the taking but have not been taken. beyond the present generation of hybrids ( mpg, mpg with careful driving; see web site hybridcars.about.com/od/news/a/ mpgrecord. htm), there seems to be no reason why mpg is technically infeasi- ble with improved batteries, lightweight composites, and better aerodynamics. the supply side question is more vexed, but materials seem to be at the crux of all the key technologies. a quick review of the various documents suggests that wind effi- ciencies cannot improve much, but the cost per watt could be decreased through mate- rials engineering; tides/waves offer a re- spectable amount of energy, but conver- sion requires system costs (limited by materials) that are currently prohibitive; nuclear energy is undergoing a renais- sance, but it seems unlikely that a new generation of plants will be built unless we have materials that address the problem of low-level waste disposal. solar energy offers the greatest hope—being by far the largest carbon-free energy resource—but depends on new materials for better pho- tovoltaic efficiencies and (perhaps just as importantly) for low-cost ac/dc converters, better packaging, and improved efficiency in photochemical and solar thermal tech- nologies. carbon sequestration is con- strained largely by engineering costs, but even here i believe materials will turn out to be a large part of the answer. so while physicists led the original manhattan project, the energy manhattan looks (at least to this “unbiased” observer) to be a materials project. but it also differs in another important respect. the manhattan project required one device (or a few) that could be built as expense-is-no- object. don’t know of an efficient way to separate isotopes of uranium? just go ahead and build enough accelerators to send a few kg of material round a mass spectrometer. energy is different. we don’t need one of anything. we need billion m of photovoltaic systems, bil- lion solid-state lights, and a billion high- efficiency cars. and, most importantly, we’ll need it all cheap. this changes the nature of the project, because, as a rule, governments don’t do lots, and they never do cheap. so the energy manhattan will require not only an unprecedented inter- national collaboration; it will require unprecedented coupling of the public and private sectors. it will call for simple and pragmatic approaches as well as visionary leaps. getting industry involved could be simple (carbon credits, incentive schemes) or very complicated (joint government/ industry projects), but the scale of the challenge makes it essential that we learn how to do it. so, how do we go about making this happen? this will not be quick or easy. indeed, i suspect it will not be as quick or even as straightforward as the original manhattan project. governments, univer- sities, and corporations are all going to have to reach across divides (financial, organizational, geographic) that make them uncomfortable. the solutions will be complex and multifaceted, and the pro- grams unwieldy. but i think we have to take this challenge on because the alterna- tive is too terrible to contemplate. and we have to take it on with urgency and in fear because, as in the original manhattan project, many in the technical community are afraid that we may already be too late. david j. eaglesham mrs president president@mrs.org a global “manhattan project” for the energy crisis “…we know that it takes energy to make people rich and that rich people burn more energy.” www.mrs.org/publications/bulletin https://doi.org/ . /mrs . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /mrs . https://www.cambridge.org/core https://www.cambridge.org/core/terms economic and other factors affecting petroleum exploration: abstract association round table shore winds is moved into clay dune complexes and eventually carried downwind to develop loess sheets. this extensive up- wind deflation of the system is accompanied by windward accreting clay-sand ridges with nuclei composed of either beach-ridge remnants of a pleistocene barrier-strandplain sys- tem or remnants of inter-blowout areas developed during early phases of the deflation of the coastward margin of the system. principal source of sand and loess is, therefore, local, repre- senting reworking of underlying, older sands. a sand source resulting from longshore convergence and inland transport from padre island accounts for only the minor, local infllling of laguna madre in the land-cut area, and is not the principal source of eouan sand throughout the system. facies fabric within pleistocene depositional systems provides principal con- trol of environments, sedimentary processes, and resulting fa- cies within the subsequent eolian system. bruce, c. h., mobil oil corp., corpus christi, tex. pressured shale and related sediment deformation—mecha- nism for development of regional contemporaneous faults regional contemporaneous faults of the texas coastal area are formed on the seaward flanks of deeply buried unear shale masses characterized by low bulk density and high fluid pres- sure. from seismic data these masses have been observed to range in size up to mi wide and , ft vertically. these features, aligned subparallel with the coast are en echelon or branching in pattern, and represent residual masses of under- compacted sediment between sand-shale depoaxes in which greater compaction has occurred. most regional contemporane- ous fault systems in the texas coastal area were formed during times of shoreline regression when the duration of fault devel- opment extended over short periods of geologic time, and where comparatively simple down-to-the-basin fault patterns were developed. in cross-sectional view, faults in these systems flatten and converge at depth to planes related to fluid pressure, and form the seaward flanks of underlying shale masses. data indicate that faults formed during time of shoreline regression were developed primarily through differential compaction of adjacent sedimentary masses. these faults die out at depth near the depoaxis of the sand-shale section. in areas where subsidence exceeded the rate of deposition, gravitational faults developed where basinward sea-floor incli- nation was estabushed in the immediate area of deposition. some of these faults became bedding plane type when the incunation of basinward-dipping beds equaled the critical slope angle for gravitational slide. fault patterns developed in this manner are comparatively complex and consist of numerous antithetic faults and related rotational blocks. nondepositional (structural) faults are common on the land- ward flanks of deeply buried shale masses. many of these faults dip seaward and intersect the underlying low-density shale at relatively steep angles. conclusions derived from these observations support the concept of regional contemporaneous fault development through sedimentary processes where thick masses of shale are present and where deep-seated tectonic effects are minimal. butler, e. a., and h. w. simpson, atlantic richfield co., dallas, tex. dlversnt-equitability analysis as p a l e o e c o l o o i c t o o l diversity-equitability analysis of microfaunal data as used by beerbower and jordan shows promise of being a rapid and useful technique for mapping paleoenvironmental gradients. it may even provide a more satisfactory definition of environmen- tal boundaries than biofacies analysis based on taxonomic com- position. faunal diversity is calculated as shannon's information the- ory average uncertainty measure. using this diversity measure, a few equally common taxa can yield as high a diversity index as many unequally common taxa. lloyd and ghelardi's equita- bility index may be used to separate these two diversity compo- nents and refine seemingly homogeneous data. recent microfaunal data from barnstable harbor, massa- chusetts, and the northern gulf of mexico have been subjected to diversity-equitabihty analysis. from barnstiible harbor, con- tours based on the equitability index can be related rather clearly to tidal action within the harbor. a diversity-equitability plot of published holocene gulf of mexico data reveals that some environments may be characterized by a unique d / e range. although these results must be considered preliminary, an analysis of parts of the lower miocene sequence in block field, high island area, oflshore texas, shows that the techni- que merits further consideration and is potentially a very useful tool for both identifying and mapping ancient environments. clark, h. c , dept. geology, rice univ., houston, tex. paleomagnetism of late pleistocene-holocene sediments, gulf of m e x i c o detailed paleomagnetic studies have been made on sedi- ment cores selected along north-south lines in the eastern and western gulf of mexico. the piston cores were sampled at - cm intervals immediately upon extrusion and measurements of natural remanent magnetization (nrm) were made using a hz spinner magnetometer. excursions of the geomagnetic field are recorded at levels in many cores. extrapolation of the zy boundary in the western gulf indicates that the younger feature is between . and . x ' years bp, and is consistent with the age determination of the laschamp event. dates are not available for the eastern gulf cores, but the depth of the paleo- magnetic feature correlates with the expected sedimentation rates. the older feature is less distinct and further extrapolation of the zy boundary places it between . and . x \(fi years bp. this age is within the range of a geomagnetic feature that is not the laschamp. these re ".ults show that with extreme care, paleomagnetic measureme its may be used as a stratigraphic tool in the gulf of mexico. several points should bi considered. first, because of the high sedimentation rates, the yotmg features described herein are the only ones expected in piston cores from this region. second, direction scatter is quite pronounced in the upper / m and lower few centimeters of several cores. corre- lations at these levels are difficult. finally, as measurement of the geomagnetic features described lasted for only a short time and did not traverse a full °, dense sampling is recom- mended to assure their definition. crandall, k. h., consulting geologist, piedmont, cauf economic and other factors affecting petroleum exploration there is today almost universal agreement that we are facing a potential energy crisis, both imminently in the u.s. and possibly worldwide after the turn of the century. all studies of energy supply and demand indicate such tremendous growth in demand tiiat conventional sources will be hard pressed to sup- ply it. the short-range aimual growth rate in domestic and free- world demand for petroleum is estimated at % and / % respectively, resulting in million and million bbl/day total demand in . by u.s. demand will be nearly million bbl and free foreign need nearly miuion bbl/day. the areas which will supply this demand, especially for fhe u.s., ark quite imcertain because of the bewildering variety of poutical, legal, and environmental factors—as contrasted with purely economic ones—which will be of critical influence. therefore, it is difficult to forecast the areas and the amounts and costs of exploration and development, as well as prices and earnings. one thing is certain, however, there will be a growing short- age of domestic crude and an increasing dependence on foreign suppues. both the cost and dependabiuty of the latter are questionable in view of political considerations and the policies and actions of opec. association round table any interruption of our foreign energy supplies would have a dramatic effect on our economy and security and would show the dangerous results of the lack of a coherent and positive energy policy. there are very few discovered but undeveloped oil reserves in the u.s. except on the north slope, and those probably cannot be made available before . though the recent npc-aapg study indicates almost bilhon bbl of undiscovered but expectable recoverable u.s. reserves, any large increase in ex- ploratory effort to find them cannot have any great effect on our crude deficit before because of the necessary lead times. it is obvious, however, that certain steps can and should be taken immediately to encourage or to cause such an increase so that the period of danger to our economy and security will be as brief as possible. fitzgerald, d. m., and a. h. bouma, dept. oceanogra- phy, texas a&m univ., college station, tex. consolidation studies of deltaic sediments the texas colorado river delta, which built across mata- gorda bay between and , was selected for consolida- tion research. the objectives were to observe structural changes which occur wjien deltaic sediments undergo primary consoli- dation, and to correlate these consohdated sedimentary struc- tures with those reported from ancient deltaic environments. double cores were collected along a traverse parallel with the main river channel in the southeast lobe of the delta. one core was sput lengthwise, described, and radiographed. an analo- gous undisturbed section of the second core was then selected for consohdation. consolidation, through vertically compressing the sediments, partly creates new structures or makes poorly visible structures more discernible. it was noted in some cases that convolute laminations and recumbent folding formed after sections con- taining parallel laminations were consolidated. it was also ob- served that apparent homogeneous sections, after compaction, changed structurally to reveal parallel laminations. consequently, it should be realized that consolidation will aitect unconsolidated sediments and that these changes should be considered when comparing recent and ancient environ- ments. floyd, b. l., independent, portland, tex. drilling funds and the energy crisis (no abstract submitted) galloway, w. e., continental oil co., exploration re- search div., ponca city, okla. slcnihcance of r e s e r v o i r d i a g e n e t i c alteration for petroleum exploration, gulf of alaska tertiary basin the tertiary clastic section of the gulf of alaska sedimen- tary basin is considered an important potential future petro- leum province. considerable work in the onshore area has been carriesl out by industry preparatory to a projected sale of fed- eral leases on the continental shelf. examination of numerous samples collected from measured sections in oligocene to pleis- tocene strata has shown that the sandstones are mineralogically immature and unstable. diagenetic alteration of these potential reservoir sands at shallow to intermediate depths of burial has resulted in the ubiquitous formation of authigenie clay rims and coats around detrital grains and of poie-filling zeolite cements. these diagenetic alterations adversely affect both porosity and permeability and will provide a major limitation on the thick- ness of the sedimentary section than can be considered pros- pective. a compaction versus depth gradient, which is related to the sandstone porosity gradient, can be determined in off- shore areas by combination of seismically derived interval, velocity depth profiles, with a velocity-density calibration based on well data from the hecate strait (a geologically similar pacific margin basin lying off british columbia). the resultant density configuration can be cross checked by gravity modeling along the same seismic line. work on a line off cape yakataga shows that the prospective section is characterized by a high velocity and density gradient, indicating rapid loss of reservoir porosity with increasing depth of burial, as predicted by the onshore diagenetic model. semiquantitative evaluation of the compaction profile using the onshore reservoir data suggests that even in the youngest sections porosity decreases to less than % at depths of , to , ft. guevara, e. h., and r. garcia, bur. econ. geology, univ. of texas at austin, austin, tex. depositional systems and oil-gas reservoirs in queen city formation (eocene), texas regional surface and subsurface studies indicate that thick deltaic (queen city formation) and thin shelf (reklaw and weches formations) sequences compose the stratigraphic inter- val between the top of the wilcox group and the base of the sparta formation. in east texas, the queen city formation accumulated as part of a high-constructive, lobate delta system; and in south texas, as part of a high-destructive, wave-domi- nated delta system. in south texas, principal facies are mean- der-belt sand, lagoonal mud, stacked coastal barriers, and pro- delta-shelf mud facies; in east texas, delta plain, delta front, and prodelta facies are dominant; and in central texas, the principal facies are strandplain sands originated by southwest- ward longshore drift of sediments from the high-constructive delta system. facies distribution, composition, and size of the deltas in east texas are similar to lobes of the holocene high-construc- tive mississippi delta system and to ancient deltas in the lower part of the wilcox and in the jackson groups of the gulf coast basin. fluvial-deltaic sediments of south texas are comparable to pleistocene high-destructive wave-dominated facies on the surinam coast, to the holocene rhone delta system, and to ancient deltas in the upper part of the wilcox group. queen city deltas prograded gulfward over shelf muds and glauconites of the reklaw formation; they are overlain by comparable shelf facies of the weches formation. in east texas, deltaic facies wedge out eastward; terrigenous elastics of the high-destructive deltas extend southward into mexico. hydrocarbons are produced from thin strike-oriented sands downdip from the belt of maximum sand thickness of the high- destructive deltas in south texas; only a minor amount of oil and gas has been obtained from delta front and distributary channel sands of the high-constructive deltas in east texas. haas, m. w., vice-president for exploration, humble oil & refining co., houston, tex. petroleum exploration and environmental conservation u. s. faces energy crisis.—v. s. energy demands will nearly double by . all our principal sources of fuel will be needed to meet the demand; if domestic supplies cannot keep pace, we face increasing reliance on foreign oil. energy and public iands.—much of u. s. energy potential, including offshore oil and gas reserves, is on publicly owned lands. potentially productive acreage in the federal and state domain should be made available to industry in a manner designed to maximize timely development. environmental delays.—a principal factor in delaying explo- ration of frontier areas is environmental concern. many envi- ronmental objections are founded on the argument that oil and gas development is incompatible with other uses of the same land or water area. compatible use.—if exploration is to proceed at a pace con- sistent with national needs in the future, the concept of compat- ible multiple use of lands must be established as national pol- icy. industry must demonstrate from available examples that this concept is sound and results in maximum benefits to public and private interests. geologisls must contribute.—petroleum geologists should bring their knowledge to bear on public environmental issues and work for reasoned solutions based on scientific fact. much exploration today awaits public consent; geologists must aid in showing pubuc that energy-environmental problems can be february , volume , number american association for the advancement of science scienr-e sers es its readers as a forum for the piesent:.tion and discussion of imiportant issues r-elated to the advancement of science, inclulding ,he prescntaition of minority or conflicting points of view, rather than by publishing only milaterial onl hich a consensus has been reached. accord- ingly, all a tidles plublishcd in si ieni e-including ditorials, news and comment, and book rcviews -aiec signed and reflect the individual views of the .ilr th a.nd not oflicial points of v,ie%v adopted by ihe aaas oi het ilstitlitions ws ithr hrich the authors -t e iffiliratedl editorial board al frli) broswn lamnes f. crosw styn ouit s. kits an k ' i ss fiink w. liuinani m \xinr. sin(ilr gordon vwolnian / hi hi- ri s. uc iii\ sski' i()ni .i) l indsley n. bru(e hannay ituit i'airick d)uina ld ki:n ni osldsyr ( [ihi. n(on i's(n d)%nii e-. kosniland, jr. editorial staff editor philip h. abelson p iblislier busiiess mana,rger \wil iasr iit vasn ans nussisaunr .tlagitng e(ditor: iroberi v. ormes assistant editors: ellen e. murphy. john e. uingli: as.sistart to thle ei/itor: nancy [teimourian n isa iil c(.oiotient: john walsh, luther j. cariiilr, dluborash shapley, ltoberi' gillette, nicho- las wade, constance holden, barbara j. culliton. schelrrainle nack resear(ih newrs: allen l. isanimond, william ). n i .z tiis,\is s h. maun ii, jean l. niarx, a\iihirur 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( - - ) editorial correspondence: massa- chulsetts ave., nw, washington. d.c. . phones: (area code ) central oflice: - ; book re- views: - ; business oflice: - ; circula- tion: - ; guide to scientific instr-uments: - ; news and comment: - ; reprints and permissions: - ; research news: - . lreviewing: - . cable: advancesci, washington copies of 'insti uctionls for contributors" can bc obtained fi-om the editorial oflice. see also page xs, cietlice, decemiiber . advertising cor- respondence: room ( , w. st., new york. n.y. . phone: -pe- - . sci:ence no easy way out of energy crisis all over the world, peoples and governmnelts have been unlable to responid realistically to the sudden changes in the availability and price of energy. in the united states, a search for scapegoats is being coin- ducted on the massumlption that if the culprits can be identified and chastised, thc problem will go away. on the international scenie, the conslminlg nations have been adopting an every-manl-for-himiiself ap- proach that guarantees additional hardship for all. many stories in the mass media have the commoni thrcad that the crisis was created and is continuing because oil companiies are with- holdinig oil in order to get higher profits. thus, the solution to our problems is simple: force the conmpanies to disgorge! escape from the current travail will not be so easy, nor will it be rapid. there is solid evidence that the mnajor sins of the oil companies are not unlderproduc- tion and overstorage today, but an earlier, opposite shortcolmlilng. for decades, oil was generally produced at the maximuml allowable rate. at the samne timie, the industry did not create substantiall storage facilities or invenitories when we were becoming dependent on foreign oil. the american petroleulll institute has long compiled weekly data on the produlction, refining, acnd distributioni of oil. the patterns of report- ing were established at a time when there was no incentive to be other than honest. moreover, the tigures were corroborated by sulrveys of the u.s. bureau of mines. these figures showed that u.s. production of crude petroleulm reached its peak in , at . million barrels per day, and has beeni slowly diminlishinig since. prior to the present crisis, it had dropped to . millioin barrels ;,er day; recently production has been . million barrels per day. in their policies with respect to storage facilities anid inventories, the oil companies have been largely guided by an attempt to hold down costs. it is expensive to mainitain large inventories. so assiduouls have the companies been in this respect that they have endangered the national security. invenitories of some of the products, such as gasoline, would, if fully available, last about days. however, only a part is available. some is in pipelines, some is in tankers, and somle is beinig processed. the companies do not have the huge excess storage capacity to hide significant amounts of oil. recently, there have been tales of speculators' storing gasoline in vacanit filling stations. a typical older filling station has a capacity of , to , gallons. weekly u.s. consumption is , million gallons. the reported hoardings are little more than drops in the bucket in comparisoni. others who have searched for an easy way out of the eniergy crisis have pointed to the possibility of a quick end to the arab oil embargo. this ma.ly or may not come soon, and when it does, it miay or mnay not lead to substantially grea,ter supplies of oil. if production is to be in- creaised rapidly, the increase must come largely from the arabiani peninsulal. there, in sauldi arabia, kuwait, and some smaller states, is about hailf the free world's oil. these states, with a total population of less thain nmillion, are enjoying unprecedenited power. with return per barrel having quladrupled over that of a year ago, they have tar more income than they caln use. kiuwait, with a populationi of , , will receive about $ billion this year. an increase in productioni wouldl not appear to serve any usefull purpose for them. more than a monith has passed since the big price increases were anlloulnced. the lack of conicerted, conistructive responise by the billioiis of people who must pay can only enlcourrage the producin(g counltries to tightenl the screws again and again. pimiii h. abenlson o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ no easy way out of energy crisis philip h. abelson doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the trademark of aaas. is a registeredscienceadvancement of science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for thescience by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ this paper is part of the proceedings of the international conference on big data (big data ) www.witconferences.com © wit press, www.witpress.com issn: - (paper format), issn: - (online), http://www.witpress.com/journals doi: . /dne-v -n - - s.j. park et al., int. j. of design & nature and ecodynamics. vol. , no. ( ) – future disaster scenario using big data: a case study of extreme cold wave s.j. park, d.w. kim, j.h. kim, j.h. chung & j.s. lee safety division, national disaster management research institute, south korea. abstract the ability to predict the future was considered a very important factor for humanity since long ago. future prediction, which was non-scientific, took on significant developments with the advancement of science and technology. nevertheless, predicting the future is still not an easy task. therefore, it is more essential to develop diverse future scenarios for establishing policies with a clear vision on the personal, or even national levels rather than attempting to precisely predict a specific future event. particularly, future research plays a crucial role in the field of disaster management to prevent national crises. future disasters could also result in an unimaginable scale of damages due to the complex network develop- ment of our society. thus, it is necessary to develop scenarios in advance from the perspective of potential damages caused by disasters. future scenario development largely comprises quantitative and qualitative methods, which are applied iden- tically in the field of disaster management. quantitative method is developed using various statistical methods based on numerical data, while qualitative method is developed based on the intellect of a group of experts. in this study, the latter method is used because of the unpredictable nature of disasters. furthermore, in order to provide a solution for the biased opinions that may occur from the group of experts, big data is used to propose a method for developing future disaster scenarios. the results from this method are preferred to efficiently develop future disaster scenarios, because the opinions of the group of experts are mostly biased. keywords: big data, cold wave, future disaster, future scenario. introduction the future is filled with uncertainties, and it is nearly impossible to predict the future. nevertheless, the human race has always had a desire to foresee the future since long ago because knowing the future was regarded as very important to ensure better lives for the people. in the past, predicting the future by means of astrology or palm reading was considered a non-scientific practice. however, due to the recent advancement of scientific technology, prediction of the future has become an area of academic study since not too long ago. nevertheless, predicting the future is not an easy task. many people are devoting their lives to studying the future to ensure better lives tomorrow. the future is uncertain. however, the process of establishing a vague outline of the future could assist in establish- ing policies with a clear vision on the personal and even national levels [ ]. with respect to studying the future, it is necessary to devise a method to come up with diverse future scenarios rather than attempting to predict an uncertain future because scenario development is far more effective com- pared to proposing an absolute prediction of an uncertain future. such future scenario development is very necessary in the area of disaster management. disasters could lead to major social chaos and national crisis. thus, if we could devise strategies and policies to counter disastrous situations by developing future disaster scenarios, the rate of damage caused by disasters could be minimized. the rapid advancement of society is leading to more complex s.j. park et al., int. j. of design & nature and ecodynamics. vol. , no. ( ) social situations and the scope of potential disasters is also becoming greater. particularly, climate change, aging society, deterioration of facilities, and other such environmental/social trends are add- ing to the complexity of social changes. such aspects could cause situations where traditionally experienced disasters lead to other unexpected disasters – ]. take for example, the major earth- quake in eastern japan in , which caused a tsunami and led to the fukushima nuclear accident. this incident clearly shows us that a disastrous event in our society causes a chain reaction to increase the rate of the severity of damage. in other words, the disasters that may take place in the future will lead to consecutive damages due to the major, complex, and intricate network established in our society. therefore, the task of developing future disaster scenarios requires the general under- standing of disasters itself, as well as of the diverse mechanisms of our society. there are many ways to develop future scenarios, but it could be largely divided into a quantitative method and a qualitative method [ ]. quantitative method refers to a method used to predict the future using various statistical methods based on numerical data. on the other hand, qualitative future scenario development method requires a group of experts from various fields to use their intel- ligence to develop future scenarios. there are cases of future disaster scenarios that have been developed through qualitative and quan- titative methods. first, the climate change scenario [ , ] developed by ipcc is a chief example of a future scenario developed using statistical methods based on numerical data. climate change sce- nario is a scientific future scenario developed based on the prospect of socio-economic advancement and greenhouse gas emissions. in addition, england developed a future flood scenario for as near as to as far as based on the greenhouse gas emissions scenario [ ]. the advantage of such scenarios developed based on past data is that it is scientific and quantitative. however, it does have its limitations for studying future disasters to identify and foresee unexpected situations in the future. on the other hand, the qualitative future disaster scenario has a risk register in the risk manage- ment program specified in iso , which develops future scenarios based on the intellect of expert groups. the major advantage of the risk register method is that it puts unexpected events in developing future disaster scenarios, and this method has been used in the united states, england, and canada [ – ]. however, this method is solely dependent on human opinions, which means that there could be biased opinions depending on the group of experts. nevertheless, the development of future disaster scenarios through a qualitative method based on the intellect of a group of experts is considered appropriate due to the nature adopted for predicting future disasters. then, how can we overcome the limitations present in developing future disaster scenarios using qualitative methods? we decided to incorporate the use of big data. that is, prior to depending solely upon the intellect of experts, rough scenarios were created using all data with regard to past disas- ters, which are available, for developing a final future disaster scenario. by doing so, we attempted to overcome the limitations present in the qualitative future disaster scenario development method. procedure of future disaster scenario using big data this is an introduction of the procedure using big data, for future disaster scenario development. first, check for data that could be used for future disaster scenario development. due to the nature of future disaster studies, non-definite data such as news contents are more useful compared to defi- nite forms of data. the reason for using news data is because it clearly indicates the cause, damages, and cause-and-effect relationship, which are not indicated in various reports with respect to disaster events, and it also indicates the time and place of the disaster. therefore, texts are retrieved from the accumulated news data of domestic press agencies based on keywords related to the disaster scenario development. s.j. park et al., int. j. of design & nature and ecodynamics. vol. , no. ( ) news data categorized by science, economy, society, etc. are processed through a stage known as text parsing. the parsing process divides the news text sentences into words, and the words are divided into parts of speech. it is then saved as data. the divided text data is put through a filtering process to extract the desired information. filtering excludes unnecessary terms and parts of speech from the words divided into parts of speech for analysis and generates a statistical value of the words from the news data. these two processes create and save a table that illustrates the role and fre- quency of words, and the information of the relevant document (fig. ). in addition, this process allows for topic modeling, which illustrates the main topic of the numerous texts, as well as network analysis, which observes the relationship between words. svd algorithm is used in the topic mod- eling stage. svd stands for singular value decomposition, which is created based on the eigenvector value attributable to words categorized according to specific topics in the term-docu- ment matrix saved in a table format, as shown in fig. (fig. ). through this method, topic modeling and network analysis are possible. this technique of acquiring desired information through a series of text-based processes – parsing, filtering, topic modeling, and network analysis – is called text mining. we primarily created a causal loop draft, as shown in fig. , using the data acquired through text mining based on news text data accumulated over the past years [ ]. although it requires redun- dant work of having to review the news contents once again, analyzing the text filtered through text mining is not very time consuming. while creating a causal loop draft based on the text mining results, we organized a group of experts from areas of related keywords based on the generated draft. it is preferable to have experts from diverse fields with extensive expertise. a part of the group of experts must include individuals who can understand the general overview of the causal loop to figure : an example of text parsing and text filtering. figure : description of svd algorithm for topic modeling. s.j. park et al., int. j. of design & nature and ecodynamics. vol. , no. ( ) propose a direction for the scenario. the intellect of the organized group of experts is used to pro- duce a final causal loop through several updates of the causal loop draft, based on which a future disaster scenario is proposed. future disaster scenario on extreme cold wave this study introduces an example of winter cold wave related future disaster scenario development. as described previously, first and foremost, all data required to develop a cold wave related future disaster scenario were reviewed. with regard to the cold wave related big data, texts from news data concerning annual records of disaster reports and the resulting damage expenses and casualties accu- mulated from press agencies from to were collected. disaster reports were used for the purpose of understanding the situation at the time, and news data were generally used to develop the future disaster scenario. thus, approximately , news articles were extracted from years of news data based on the keywords ‘cold wave’ and ‘heavy snowfall’. then, the extracted texts were put through processes of text parsing, filtering, topic modeling, and network analysis. we created a cold wave related causal loop draft based on the information acquired through the text mining pro- cess (fig. ). we categorized the elements affected by cold waves based on this draft. based on the catego- rized areas, experts from academic circles and research organizations who were involved in cold wave related researches were hired. a group comprising experts were organized from diverse areas (e.g. transportation, agriculture, health, climate, administration, etc.) (table ). the group included individuals who had an understanding of the general overview of the cold wave related causal loop. the intellect of the organized group of experts has been used to develop a final causal loop through numerous updates of causal loop draft (fig. ). during the process of taking advantage of the intel- lect of the group, we conducted interviews with industry experts considering the risk of unprecedented figure : causality loop of earthquakes (helbing et al. [ ]). s.j. park et al., int. j. of design & nature and ecodynamics. vol. , no. ( ) f ig ur e : c au sa l lo op d ra ft r el at ed w it h ex tr em e co ld w av e. s.j. park et al., int. j. of design & nature and ecodynamics. vol. , no. ( ) figure : causal loop related with extreme cold wave. table : experts participated in developing future disaster scenario on cold wave. name field institution chung, y.s trans-portation the korean transport institute lee, j. woo, y.j. fire korea fire protection association kim, k.s. agriculture crop science & biotechnology, seoul national university yook, s.y. livestock animal and plant quarantine agency han, i.s. fishery national fisheries research and development institute kim, k.s. local government busan development institute yun, y.b. ulsan development institute won, j.s. seoul development institute kim, h. health health science, seoul national university lim, s.h. korea centers for disease control and prevention ju, y.s. social medicine, hallym university kim, j.y. facilities deawoo engineering & construction company kim, b.m. climate korea polar research institute lee, d.g national institute of meteorological research lee, s.h. energy korea gas corporation jung, j.c. forest korea national park service oh, y.k. overall korean institute of public administration lee, d.k. landscape architecture, seoul national university s.j. park et al., int. j. of design & nature and ecodynamics. vol. , no. ( ) table : proposal of notable future disaster scenarios based on causal loop. field disaster scenario transportation • road standstill / reduction of snow removal resources / degradation of restora- tion equipment performance → problems in supplying resources → increased potential of isolations on roadways • icy road → difficulties in snow removal and restoration → extensive time consumption for restoring → additional damages and losses → large-scale traffic chaos transportation & industry • strong cold wave and heavy snow → logistics transportation system errors → reduced sales • strong cold wave and heavy snow → difficulty in commuting → work hour reduction → reducing productivity agriculture & fishery • temperate fruit tree growing region and warm current fish species are moving and expanding to the north → severe unexpected cold waves → large scale mortality due to relative vulnerability to low temperatures health & environment • human body adapting to warmer climates → unexpected cold waves → significant shock • increase in the number of the senior / rapid increase of air pollutant emission from china during the winter season → northwesterly winds blowing → increase the rate of damage → increased number of patients → medical facilities overloaded → secondary damages facilities • industrial facilities and infrastructures developed during the s → deteriorating over time → heavy snowfall → collapse accidents • after the winter season → frozen facilities begin to melt and thaw → collapsing buildings and facilities facilities & forestry • cold waves → freezing reservoirs in mountain / rupturing water mains → potential shortage of drinking water • accompanied by heavy snow, cold wave → difficulty in entering the mountain of large fire trucks → difficulty of emergency water supplies forestry • frequent droughts due to climate change → decreasing of the rate of precipitation in winter and spring → reduced amount of water in catchments → difficulty in procuring water to suppress forest fires • cold wave → freezing the water catchments → making the situation even worse • accompanied by gusty winds, recent cold waves → raising further concerns for major forest fires. energy • sever winter drought → hydroelectric power suspension → winter energy crisis • severe unexpected cold wave → increased demands of gas energy → winter energy crisis s.j. park et al., int. j. of design & nature and ecodynamics. vol. , no. ( ) cold wave disasters that may be caused by global megatrends such as climate changes, aging socie- ties, urbanization, etc. notable future disasters scenario based on the final causal loop is proposed in table shown below. discussion & conclusion based on the results of the future disaster scenario using big data, we were able to conclude that a single influential factor could cause chain reactions in various unexpected areas. this research also demonstrated that text-based big data could be used for creating future disaster scenarios. this aspect played a crucial role supplementing the limitations of a future scenario through qualitative methods based on the intellect of an expert group. in other words, it gave consideration to the biased opinions found in qualitative methods resulting from solely depending on the intellect of the expert group. also, a scenario based on big data was efficient in the fact that it minimized the time and scope of organizing the expert group. based on in-depth interviews with the expert group, they pointed out that the draft scenario created based on news data played a decisive role in completing the future disaster scenario. nevertheless, the results of the future disaster scenario proposed in this study are still insufficient to be used as effective policy support tools to persuade policy-deciding authorities. support tools developed using quantitative methods based on non-definite and definite data are required to support such shortcomings. in future studies, numerical statistics method will be used in addition to develop future disaster scenarios to be used as effective tools for decision making. references [ ] choi, h.s., theory and methodology of futures study. korean sociological association, ( ), pp. – , . (in korean). [ ] hur, j.y. & lee, j.h., study on building a disaster management system responding to future disaster -using expert survey method. crisis and emergency management, ( ), pp. – , . (in korean). [ ] boin, a., ekengren, m. & rhinard, m., protecting the union: analysing an emerging policy space. journal of european integration, ( ), pp. – , . http://dx.doi.org/ . / [ ] quarantelli, e.l., lagadec, p. & boin, a., a heuristic approach to future disasters and crises: new, old, and in-between types. handbooks of disaster research, springer: new york, pp. – , . [ ] kosow, h. & gaßner, r., methods of future and scenario analysis; overview, assessment, and selection criteria. german development institute, , pp. – , . [ ] ipcc, ipcc fourth assessment report: climate change (ar ), . [ ] ipcc, ipcc fifth assessment report, . [ ] government office for science, future flooding: executive summary, . [ ] london resilience team of greater london authority, london community risk register, . [ ] public safety canada, all hazards risk assessment methodology guidelines, . [ ] homeland security, threat and hazard identification and risk assessment guide – comprehensive preparedness guide (cpg) , nd edn, . [ ] helbing, d., ammoser, h. & kühnert, c., disasters as extreme events and the importance of network interactions for disaster response management. extreme events in nature and society, pp. – , . http://dx.doi.org/ . / - - -x_ s o c i e t y the ironbridge an asm historical landmark received: august � springer science+business media, llc and asm international asm’s historical landmark award was established in with the aim of preserving metallurgical heritage and increasing awareness of pioneering milestones of metal- working technology. the scope of the award was expanded to include man’s greatest metalworking achievements from around the world. in , the first sites outside north america were honored. one of these is the ironbridge in telford, shropshire, england. the industrial revolution transformed great britain into a world power. the beginning of that revolution is best symbolized by a simple, single-span bridge over the river severn in the town of telford. to the modern eye accus- tomed to longer, more grandiose spans, the ironbridge is not an impressive structure, but it was a major innovation when it was built in . it was the world’s first iron bridge. were it not for the technology developed by the iron- makers of over years ago, which make the ironbridge possible, the modern bridges upon which we stand, as well as skyscrapers and other modern buildings, would not be possible. that technology was first developed in coalbrookdale, only a few miles away from the ironbridge. in , a charcoal blast furnace dating back to the s was taken over by abraham darby, a quaker ironmaster. at that time, england was experiencing an energy crisis because of a shortage of its traditional fuel, charcoal. mr. darby experimented successfully with using coke in the smelting of iron ore, and iron production in england jumped as a result of this new process. within the next few decades, iron from the area was being used to build boats, buildings, and machinery of all types. in the words of thomas carlyle, british industry had ‘‘burst forth into cotton-spinning, cloth-cropping, iron- forging, steam-engining, railwaying, commercing, and careering towards all the winds of heaven.’’ the severn became the second busiest river in europe. it would be several decades later, however, before an iron strong enough for the demands of a bridge was developed. such an iron was developed in coalbrookdale, and, under the technical direction of abraham darby iii, the ironbridge was erected. despite these achievements, iron manufacturing in the telford area declined by the middle of the nineteenth century, moving to other areas of great britain where raw materials were more accessible. the foundries were abandoned and the ironbridge was scheduled for demolition until, in , the ironbridge gorge museum trust was founded to preserve these monuments to the birth of industry. dedicated to conserving the birthplace of the industrial revolution and interpreting its remains in the six square miles of the ironbridge gorge, the ironbridge gorge museum trust is an independent education charity. museum staff manages historic sites, ten of which are museums. these ten museums receive more than , visitors annually. at the coalbrookdale museum of iron, visitors may explore the site and the remains of the water-powered blast furnace where abraham darby i perfected the smelting of iron with coke instead of charcoal. this was the secret that helped make iron the essential material of the industrial resolution. in the great warehouse, models, films, and original artifacts illustrate the revolutionary techniques that made coalbrook- dale the most famous ironworks in the world. the blists hill victorian town transports visitors back to a period when this part of shropshire was ruled by coal metallogr. microstruct. anal. ( ) : – doi . /s - - - and iron. it shows a complete range of the industrial, social, domestic, and business life of a typical community based upon the principal industry—ironmaking. the industrial monuments include blast furnaces, a brick and tile works, and an inclined plane that carried barges from the top canal to the lower one at coalport. in , the ironbridge gorge became one of the first sites in the united kingdom to be awarded world heritage status by unesco. the designation of the ironbridge gorge as a world heritage site recognized the area’s unique contribution to the birth of the industrial revolution in the eighteenth century, the impact of which was felt across the world. it was the achievements of pioneer- ing industrialists including abraham darby, william reynolds, and john wilkinson that led to the ironbridge gorge becoming by the close of the eighteenth century the most technologically advanced area in the world. the ironbridge was built not only to allow raw mate- rials and people to get from one side of the river to the other but also to demonstrate to the world at large that cast iron could be used as a structural material. closed to road traffic in , it has since been fully restored and stands proudly at the heart of the ironbridge gorge world heritage site. the former tollhouse on the south side houses a tourist information centre, as well as displays giving the full history of the bridge that has been rightfully described as the ‘‘symbol of the industrial revolution.’’ ‘‘this is really mohammed’s tomb as far as the industrial world is concerned,’’ said mark harwood-little, the trust’s director, ‘‘for out of this came iron to build an empire.’’ the asm historical landmark award was presented by donald j. blickwede, asm president at the time, and allan ray putnam, then asm senior managing director, at ded- ication ceremonies in may . the citation on the award plaque reads: ‘‘the first iron bridge, cast of iron smelted with coke, erected in , symbolizes pioneering metal- lurgical accomplishments, leading to britain’s renown for engineering and manufacturing innovations.’’ dr. blickwede said, ‘‘we have a special opportunity to honor the first of the firsts, that accomplishment which preceded everything we have attained in metalworking since the industrial revolution. we will never forget that all of today’s turbojets, alloy steels, and other metal and materials advances came about because an enterprising englishman substituted coke for charcoal nearly three centuries ago and began the modern age of metals.’’ acknowledgments information in this article has been adapted from ‘‘three asm historical landmark awards presented,’’ by kevin j. bouffard, asm news, august . for additional information about the ironbridge gorge museums, see http://www.ironbridge. org.uk/. the ironbridge at coalbrookdale, england. photograph by george krauss metallogr. microstruct. anal. ( ) : – http://www.ironbridge.org.uk/ http://www.ironbridge.org.uk/ 	the ironbridge 	an asm historical landmark 	acknowledgments doi: . /j.bbamcr. . . biochimica et biophysica acta ( ) – www.elsevier.com/locate/bbamcr review cardiomyocyte necrosis: alternative mechanisms, effective interventions nektarios tavernarakis ⁎ institute of molecular biology and biotechnology, foundation for research and technology, vassilika vouton, po box , heraklion , crete, greece received january ; accepted january available online january abstract necrotic death of cardiac myocytes is a major contributor to heart failure associated with several cardiac pathologies such as ischemia and reperfusion injury. preventing cardiomyocyte necrosis is an important challenge towards the development of effective strategies, aiming to battle cardiovascular disorders. while, necrotic cell death was traditionally considered a passive and chaotic process, emerging evidence indicates that specific molecular mechanisms underlie cellular destruction during necrosis. elucidation of these mechanisms will facilitate therapeutic intervention against heart failure. © elsevier b.v. all rights reserved. keywords: ischemia; lipid; mitochondria; necrotic cell death; oxidative stress; peroxidation; reperfusion three major types of cell death have been described in diverse organisms, apoptosis autophagic vacuolation and necrosis [ – ]. although necrosis has been associated with extensive cell loss that accompanies many devastating human pathologies such as stroke, heart diseases and several neurodegenerative conditions, the biochemical pathways med- iating the necrotic destruction of cells have long remained obscure. one of the main reasons why molecular characteriza- tion of necrosis lagged considerably behind that of the other two types of cell death has been the – until recently – prevailing notion that necrosis is a catastrophic type of cell death that is uncontrollable and does not involve any specific mechanisms [ ]. why study necrosis if there is nothing there to find? however, this concept is being overturned by findings in organisms ranging from the lowly nematode worm caenor- habditis elegans to mammals, which reveal that necrotic death is carried out by conserved cellular processes. genetic and biochemical dissection of these processes shows that, rather than being a disorganized breakdown of the cell, necrosis is orchestrated and executed by appropriate mechanisms, depend- ing on the death initiating stimulus [ ]. what triggers necrotic cell death? cells suffer necrosis when exposed to excessive stress and adverse environmental conditions such as lack of ⁎ tel.: + ; fax: + . e-mail address: tavernarakis@imbb.forth.gr. - /$ - see front matter © elsevier b.v. all rights reserved. doi: . /j.bbamcr. . . oxygen or essential nutrients (i.e. in the case of ischemia during a heart attack or following stroke), elevated temperature, toxic or corrosive compounds and excessive mechanical strain (i.e. in the case of trauma). in addition to external predicaments, necrotic cell death can also be inflicted by genetic abnormalities (i.e. deleterious gene mutations in neurodegenerative disorders). an important corollary of investigating the mechanisms of necrosis, highly relevant to human health, is the emerging potential for prevention or therapeutic intervention. although, once induced, necrotic cell death was considered inevitable, the recent identification of signaling pathways and genes required for cell demise offers opportunities for the development of educated intervention strategies, designed to counter or ameliorate pathological conditions with a significant necrosis component. the study by casey, arthur and bogoyevitch holds such a promise for heart damage following acute myocardial infarction and ischemia [ ]. in this and other cardiac pathologies, ensuing cardiomyocyte cell death is a major contributor to heart dysfunction and failure. oxidative stress due to accumulation of reactive oxygen species (ros) has been implicated in triggering cell death [ ]. casey, arthur and bogoyevitch show that high hydrogen peroxide (h o ) concentration causes a pattern of late-onset death of neonatal cardiomyocytes in culture. dying cells exhibit ultrastructural characteristics of necrosis, with delayed leakage of lactate dehydrogenase (ldh), which signifies compromise of plasma mailto:tavernarakis@imbb.forth.gr http://dx.doi.org/ . /j.bbamcr. . . n. tavernarakis / biochimica et biophysica acta ( ) – membrane integrity. lack of caspase- activation, which occurs during apoptosis, further suggests that cardiomyocyte death is not apoptotic. one of the traditional hallmarks of ros-initiated cell death is mitochondrial dysfunction and energy depletion [ ]. this is manifested by opening of the mitochondrial permeability transition pore (mptp), the collapse of the mitochondrial membrane potential (mmp) and the concomitant drop in atp production [ – ]. these events set in motion a battery of cell destruction cascades and at the same time, limit the capacity of the cell for energy production. intriguingly, casey, arthur and bogoyevitch demonstrate that necrotic death of cardiomyocytes under oxidative stress does not involve opening of mptp of loss of mmp. furthermore, cellular atp content is only transiently reduced upon treatment with h o and in fact, it later recovers to close the normal levels. these observations suggest that death is not merely the result of an inescapable energy crisis that undermines cell viability. what then is killing the cells experiencing oxidative stress induced by h o ? calcium-activated calpain proteases and lysosomal, acidic aspartyl proteases, which are required for necrotic cell death in c. elegans and mammalian neurons [ , ], do not appear to be involved. rather, alternative mechanisms of cell destruction might be in operation, in this experimental paradigm. casey, arthur and bogoyevitch show that lipid peroxidation is an important contributing factor. first, fig. . membrane lipid peroxidation contributes to oxidative stress-induced cell dea antioxidant defenses and causes peroxidation of plasma or other membrane lipids. p hydroperoxides and aldehyde byproducts such as -hydroxynonenal (hne). in turn, h transporters and pumps [ , ]. the cumulative effect of such modifications is cell leukemia inhibitory factor, ros: reactive oxygen species, sod: superoxide dismuta lipid peroxidation is significantly increased upon exposure of cardiac myocytes to h o and second, inhibition of lipid peroxidation by the vitamin e analogue trolox or by the iron chelator dipyridyl prevents cell death (fig. ). what cellular processes could be stimulated or augmented to fortify cells against cell death? previous studies have shown that two hypertrophic agents, endothelin- (et- ) and leukemia inhibitory factor (lif) protect cardiomyocytes under oxidative stress from apoptotic death [ , ]. interestingly, casey, arthur and bogoyevitch have found that peroxiredoxin and alpha-b crystallin are among the proteins with increased abundance after treatment of cardiomyocytes with et- , whereas treatment with lif increases the abundance of cu/zn superoxide dismutase and hsp and [ ]. therefore, by provoking such proteomic profile changes, these hypetrophic agents may strengthen antioxidant and stress defenses of cells. indeed, pretreatment of cardiomyocytes with et- or lif inhibits necrosis induced by h o (fig. ). the totality of these findings highlight the feasibility of formulating effective interventions against necrotic cell death associated with human pathologies. this is a particularly exciting prospect, given that ischemic diseases of the heart, kidney and brain as well as neurodegenerative disorders are among the primary causes of disability, morbidity and mortality. numerous studies utilizing an assortment of experimental systems converge to the conclusion that necrosis is not simply th. excessive accumulation of reactive oxygen species (ros) saturates cellular eroxidation compromises the integrity of these membranes and generates lipid ne may perturb ion homeostasis by interfering with the function of ion channels injury and ultimately, death. et- : endothelin- , hne: -hydroxynonenal, lif: se. n. tavernarakis / biochimica et biophysica acta ( ) – the decadent and inexorable fate of a cell otherwise not meant to die [ , , ]. understanding the intricacies of necrosis inflicted by diverse initiators will shed light into the biochemical events that transpire during cell death. the molecules enacting these biochemical events are effectors of necrosis and should, in principle, constitute excellent targets for drug development [ ] and other methodologies designed to ameliorate or block pathological cell death. references [ ] p. golstein, g. kroemer, cell death by necrosis: towards a molecular definition, trends biochem. sci. ( ). [ ] g. kroemer, w.s. el-deiry, p. golstein, m.e. peter, d. vaux, p. vandenabeele, b. zhivotovsky, m.v. blagosklonny, w. malorni, r.a. knight, m. piacentini, s. nagata, g. melino, classification of cell death: recommendations of the nomenclature committee on cell death, cell death differ. (suppl. ) ( ) – . [ ] a.l. edinger, c.b. thompson, death by design: apoptosis, necrosis and autophagy, curr. opin. cell biol. ( ) – . [ ] p. syntichaki, n. tavernarakis, death by necrosis. uncontrollable catastrophe, or is there order behind the chaos? embo rep. ( ) – . [ ] p. syntichaki, n. tavernarakis, the biochemistry of neuronal necrosis: rogue biology? nat. rev., neurosci. ( ) – . [ ] t.m. casey, p.g. arthur, m.a. bogoyevitch, necrotic death without mitochondrial dysfunction—delayed death of cardiac myocytes following oxidative stress, biochim. biophys. acta ( ). [ ] v.p. van empel, a.t. bertrand, l. hofstra, h.j. crijns, p.a. doevendans, l.j. de windt, myocyte apoptosis in heart failure, cardiovasc. res. ( ) – . [ ] p. nicotera, m. leist, e. ferrando-may, intracellular atp, a switch in the decision between apoptosis and necrosis, toxicol. lett. – ( ) – . [ ] j.s. armstrong, the role of the mitochondrial permeability transition in cell death, mitochondrion ( ) – . [ ] y. tsujimoto, s. shimizu, role of the mitochondrial membrane permeability transition in cell death, apoptosis ( ). [ ] c.p. baines, r.a. kaiser, n.h. purcell, n.s. blair, h. osinska, m.a. hambleton, e.w. brunskill, m.r. sayen, r.a. gottlieb, g.w. dorn, j. robbins, j.d. molkentin, loss of cyclophilin d reveals a critical role for mitochondrial permeability transition in cell death, nature ( ) – . [ ] p. syntichaki, k. xu, m. driscoll, n. tavernarakis, specific aspartyl and calpain proteases are required for neurodegeneration in c. elegans, nature ( ) – . [ ] t. yamashima, ca +-dependent proteases in ischemic neuronal death: a conserved ‘calpain-cathepsin cascade’ from nematodes to primates, cell calcium ( ) – . [ ] t. kakita, k. hasegawa, e. iwai-kanai, s. adachi, t. morimoto, h. wada, t. kawamura, t. yanazume, s. sasayama, calcineurin pathway is required for endothelin- -mediated protection against oxidant stress-induced apoptosis in cardiac myocytes, circ. res. ( ) – . [ ] f. wang, y. seta, g. baumgarten, d.j. engel, n. sivasubramanian, d.l. mann, functional significance of hemodynamic overload-induced expres- sion of leukemia-inhibitory factor in the adult mammalian heart, circulation ( ) – . [ ] t.m. casey, p.g. arthur, m.a. bogoyevitch, proteomic analysis reveals different protein changes during endothelin- - or leukemic inhibitory factor-induced hypertrophy of cardiomyocytes in vitro, mol. cell. proteomics ( ) – . [ ] w.x. zong, c.b. thompson, necrotic death as a cell fate, genes dev. ( ) – . [ ] s.y. proskuryakov, a.g. konoplyannikov, v.l. gabai, necrosis: a specific form of programmed cell death? exp. cell res. ( ) – . [ ] a. degterev, z. huang, m. boyce, y. li, p. jagtap, n. mizushima, g.d. cuny, t.j. mitchison, m.a. moskowitz, j. yuan, chemical inhibitor of nonapoptotic cell death with therapeutic potential for ischemic brain injury, nat. chem. biol. ( ) – . [ ] m.p. mattson, modification of ion homeostasis by lipid peroxidation: roles in neuronal degeneration and adaptive plasticity, trends neurosci. ( ) – . [ ] m.p. mattson, g. kroemer, mitochondria in cell death: novel targets for neuroprotection and cardioprotection, trends mol. med. ( ) – . 	cardiomyocyte necrosis: alternative mechanisms, effective interventions 	references gasifiers—a born-again technology environmental conservation may provide a means of testing the theory by molecular biological analysis, he said. 'the peculiarities of these bacteria that we discovered strongly suggest that they may be of great value for tracing early biochemical evolution on the earth,' he added. dr gest and his assistant, jeffrey l. favinger, were about to throw out the contents of a flask—from an undergraduate's classroom experiment on photosyn- thetic bacteria that had failed because of an error in preparation—when they noticed something growing near the bottom of the flask. they isolated the organism, which had been present in soil dug up by the student in front of the biology building, and realized they had discovered 'something different'. they named the new organism heliobacterium chlorum, which translates from the greek as something like 'sun green bacterium'. all green plants must have nitrogen in order to grow. though there is plenty of nitrogen gas in the air, most plants are unable to use it and must obtain combined nitrogen from other sources, such as nitrogen-rich compounds in the soil. this is the principal reason why most crop plants need to be fertilized. but because virtually all photosynthetic bacteria are also able to take nitrogen gas from the air and use it for growth, these bacteria are prominent among biological systems that are being investigated by scientists suported by the nsf as part of a fundamental effort to determine how green plants might make their own fertilizer by taking nitrogen from the air. gest & favinger found that heliobacterium has some odd characteristics. 'this bacterium is extraordinarily sensitive to gaseous oxygen. even minute traces of oxygen completely inhibit its growth,' dr gest said. 'in addition, the bacterium contains a unique form of chlorophyll, the green light-capturing pigment. a chlorophyll molecule essentially consists of four rings of atoms that are fused together, with a magnesium atom at the centre of the structure. one of the rings has a side-branch of two linked carbon atoms. in all other known photosynthetic bacteria, this side-branch also contains one oxygen atom. but there is no oxygen atom in the side-branch of the chlorophyll in the bacterium we discovered.' 'this absence of oxygen, together with the fact that even minute traces of oxygen prevent growth of this bacterium, reinforces the idea that the bacterium evolved long before there was any oxygen gas in the earth's atmosphere—in other words, long before photosynthesis by green plants was "invented",' dr gest explained. the research workers are sending batches of the bacterium to scientists at other institutions who specialize in different areas of biochemistry and molecular biology. 'this will speed up solution of the life-style mysteries of this fascinating organism, whose ancestors were at an important crossroad in evolutionary history,' dr gest said. ralph kazarian national science foundation g street, washington dc , usa. gasifiers—a born-; there is no irony in the technological lead of the philippines and brazil in developing gasifiers; for during world war ii, when europe's oil-starved economies were under military siege, 'gasification' powered more than one million vehicles. london buses could be seen towing stove-like gasifiers on trailers, while many big cars of the s sprouted devices resembling boilers on their rear ends, and sported roof-racks full of charcoal. post-war supplies of cheap oil quickly killed gasifi- cation. after all, the gas is poisonous (mostly carbon monoxide), so dirty that engines need 'constant' cleaning, and not as 'hot' as gasoline—making gasified engines sluggish. then, in the s, rapidly-rising oil prices and falling commodity prices placed oil-importing third world countries under economic, rather than military, siege. the capital cost of a gasifier system is about one us cent higher per kilowatt/hour then that of a diesel engine, again technology and maintenance and running costs are about three cents more. but fuel for the gasified diesel costs ten cents less per kwh. the total cost of power with gasification is about % less than with straight diesel. successes in the philippines and brazil have spurred aid agencies to take a hard look at gasifiers as a means of solving the energy crisis in developing countries. wood gas cannot help all third world countries: in particular, regions without trees—such as sahelian africa or the middle east—lack the fuel to run gasifiers. but many development experts are convinced that wood gas is a commodity whose time has come around again. lloyd timberlake earthscan percy street london w p odr england, uk. oil-wells blocked to prevent war damage iran has blocked all but six of its oil-wells in the offshore nowruz and ardeshir fields with cement, virtually eliminating the possibility that future iraqi missile strikes in the area could result in increased oil pollution of the gulf, according to reports reaching the world wildlife fund international. seventy-five wells in the nowruz field, and an unspecified number that includes all wells in the nearby ardeshir field, have been blocked down to the seabed, according to industry sources. all these wells will eventually have to be re- drilled to be put back into production, these sources said. the last wells were blocked in november . the world wildlife fund and other conservation groups have been alarmed at the prospect of further damage to wells that might drastically increase oil pollution of the gulf. pollution has already virtually exterminated the population of dugongs and sea snakes, and severely affected coral reefs, marine turtles, and other living things in coastal waters. wells on two platforms in the nowruz field were still burning in november after being hit by iraqi missiles in early march. at the former time there had been no recent missile strikes against oil-wells, but there have been continuing attacks on iranian shipping, the oil terminal at kharg island, and onshore pumping and storage facili- ties. offshore oil for these facilities was being produced only in the fereidoon field, which had not been attacked. meanwhile an international conference has been sched- uled in teheran to study the environmental effects in the gulf of oil pollution caused by the war. donald allan, information director world wildlife fund international avenue du mont-blanc gland, switzerland. https://www.cambridge.org/core/terms. https://doi.org/ . /s x downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /s x https://www.cambridge.org/core rrs_ _ _site.indd revista română de statistică nr. / barriers in implementation of e-business technologies in small and medium enterprises (smes) in pakistan dr. anwar ali shah g. syed university of sindh-pakistan assistant professor faiz. m. shaikh szabac-dokri-larkana articolul prezintă rezultatele cercetării prin care s-au investigat barierele de punere în aplicare a e-businsess technologies în întreprinderile mici şi mijlocii (imm-uri) din pakistan. datele şi informaţiile statistice au fost colectate de la . de respondenţi, folosind tehnica simplă aleatoare. un chestionar structural a fost dezvoltat pentru colectarea de date, fi abilitate şi validare. a fost relevat faptul că majoritatea proprietarilor de afaceri ai imm-urilor nu sunt familiarizaţi cu utilizarea internetului şi, în multe cazuri, nu sunt pregătiţi în domeniul calculatorului. se arată că guvernul ar trebui să ofere o pregătire de bază pentru întreprinderile mici şi mijlocii, să se poată utiliza calculatorul. prin punerea în aplicare corectă a tehnologiilor e- business în imm-uri în pakistan, guvernul şi celelalte organe conexe pot iniţia e-business în imm-uri pentru a obţine un avantaj competitiv. cuvinte cheie: implementare, e-business, imm-uri abstract the current research investigates the barriers in implementation of e-business technologies in small and medium enterprises (smes) in pakistan. data were collected from respondents by using simple random technique. a structural questionnaire was developed for the data collection and reliability and validity of data. it was revealed that most of the smes business owners are not familiar in using internet and in many cases they are not computer literate. it was further revealed that government should provide some basic computer training to the small and medium enterprises so they will able to use computer. the proper implementation romanian statistical review nr. / of e-business technologies in smes in pakistan, government and other related agencies can initiate e-business in smes to achieve competitive edge. key words: implementation, e-business, smes, pakistan *** the main features of sme are that it does not belong to core industry in an economy and it is “not large “.in globalization and small and medium enterprise report oecd. micro enterprise : ~ employees very small enterprise: : ~ employees small enterprise : ~ employees medium enterprise : ~ employees besides quantitative aspects (employment, capital, sales etc), smes can also be defi ned in qualitative terms. meredith ( ) suggests that the defi nition of sme must include both quantitative and qualitative aspects, i.e fi nancial and non- fi nancial measurements. the defi nition of sme as per wiltshire committee (australia) meredith , p ): small business is one in which one or two persons are required to make all of the critical decisions (such as fi nance , accounting , personnel , inventory , production , servicing marketing and selling decisions) without the aid of internal (employed) specialists and with owners only having specifi c knowledge in one or two functional areas of management. brigham and smith ( ) found that smes are more vulnerable to risk than large enterprises. walker ( ) ; debone ( ) also have similar opinion.smes have higher failure rates (cochran , ) keep inadequate records ( retch , ) lack of trained staff and far reaching policiesadn plans (welsh and white ) it skill (barry & milner ) , adequate fund to invest on it (gaskell et al ; raymond ) most smes have no proper planning , staffi ng (teethe & burn , ; miller & baser , ) and sme differs with larger enterprise in terms of product /service. offerings (reynolds et al, ). besides many views exist regarding characteristics of smes some researchers argue that the outcome of applying processes and techniques to both large and small companies are not same due to the distinct characteristics of smes .smes are not the miniature versions of large companies (macknesss, ; westheadand storey ). as per industrial policy of bangladesh larger industry is defi ned to include all industrial enterprise having more than workers and /or having a fi xed capital of over tk. million.medim industries covers revista română de statistică nr. / enterprises employing between tk. million an tk. millions. small industry means enterprises having fewer than workers and/or with a fi xed capital investment of less than tk. millions. as per bangladesh bank defi nitions: small enterprise means an entity, ideally not a public limited company that does not employ more than people if it is a manufacturing concern and persons if it is trading concern and people if it is a service concern and also fulfi lls the following criteria: ( ) a service concern with total assets at cost excluding land and building for to , to lac. ( ) a trading concern with total assets at cost excluding land and building from to , to lac. ( ) a manufacturing concern with total assets at cost excluding land and building form tk. , to tk. crores. japanese smea (small and medium enterprise agency) divides the small and medium scale enterprise of japan into four types: manufacturing and others, wholesale and retail services on the basis of capital size and employees: categories of industries capital size (millions yen) employee size manufacturing and others or less or less wholesale or less or less retail or less or less services e-commerce, e-business and icts electronic commerce, or e-commerce, is buying and selling on- line. there exist no widely accepted defi nition for electronic commerce. however, in general, e-commerce can be defi ned as any transaction with on-line commitment to buy or sell a good or service (european commission e-commerce web site) e-business is a broader term than e-commerce. it includes not only buying and selling no-line but also other aspects of on-line business activity such as purchasing tracking inventory, customer relationship management (scm) managing production, logistics and business process .e-business covers both e-commerce and that re-engineering of business processes with romanian statistical review nr. / the help of digital technologies. e-business has three main aspects (margi, l. and philip, p, .technologies.and fi rm to customers (e-commerce). information and communication technologies (icts) includes internet, extranet computer mobile devises, website, edi etc.it allows new forms of partnership between companies, suppliers and consumers, improving the way of doing business. information communication technologies (icts) helps fi rms to reduce cot and to enhance profi t. factors affecting adoption of icts by smes e-commerce enables small and medium enterprise (smes) to compete and link with large companies’ .the factors that infl uence the diffusion of and link with large companies. the factor that icts within sme s numerous. chau ( ) mehrtnes et al. , in their study identifi ed three major factors. those are perceived benefi t, organizational readiness to e-commerce and pressure from external factors. alignment of business processes with website strategy is also an important factor for launching online trading by smes (bergeron, et al ; lawrence & chau, ; poon & swatman, ; cragg, ). the benefi t, disadvantages and barriers also act as triggering forces for the smes to adopt and use e-commerce. if perceived benefi ts are higher, disadvantages are lower and barrier of e-commerce are less then certainly. smes will go for e-commerce provided that it cost effective to do so. lack of awareness, lack of training, and perceived risk work negatively for adopting e-commerce by smes. application of e-business technologies in smes • signifi cant productivity gains associated with e-commerce and supporting applications. in b b relations, electronic technologies can lead to rationalizations of business processes and signifi cant cost saving due to cost effective way of communication, better handling of information and prompt delivery (oecd, ). • shortening the design process, product customization and standardization of parts as well as lower inventory costs, faster production, lower supply costs can be attained through the use of icts (oecd, a). • electronic commerce improves possibilities for production relocation through outsourcing. direct contact can be established with suppliers as well as customers and thus greater customers as well as suppliers, loyalty could be achieve through improved supply chain management, which create new business (poon & swatman ). • reduction in transaction costs which is vital for small business is possible through the use of e-business. at the same time, improvements revista română de statistică nr. / in product quality/customers service, increasing customers’ base and close intimacy with suppliers are possible in e-business process (moodley, ). • though use of internet, smes can sell the products and services directly to the end users (mikio, k., ) and could achieve higher profi t margin that gets eaten up by the middle man in the traditional distribution channels. • use of internet system improve the crm system and allows fi rms to interact closely and customize their products and services smes are better able to handle customers with services promptly (barry & milner, ). • through engagement in e-business the smes can get direct feedback from the customers about the qualities of products and services so they can avoid costly market research. obstacles to the adoption of e-business in smes in pakistan in most national economies, smes make up more than % of the market participants, and contribute around % of direct value addition or production. why smes are contributing less in gdp of pakistan compare with developed countries. the following are the main obstacles in the development of smes in pakistan. • lack of awareness among smes about e-business technologies: pakistan smes found to be unaware about the potential benefi t of the use of ict for profi t enhancement and cost reduction. moreover they are also unaware about the recent development technologies. besides, they are feeling comfortable to do business in traditional way and have lack of initiatives to take the risk of investment on icts. • lack of icts infrastructure: to make smes engage in e-commerce, the infrastructure should be right place. in pakistan telecommunication system is not so developed, the high band with internet is not available in all places, and it is confi ned to town areas. besides, the costs of the computer and other accessories are also huge to justify investment on it. • lack of power supply: electricity is of foremost importance for uninterrupted communication with buyers, suppliers over internet. in pakistan recent energy crisis effected the growth of smes business in pakistan. • lack of finance: due to insuffi cient collateral smes in pakistan, could not avail the loan from institutional services, like commercial banks, leasing and investment companies. so smes don’t have enough funds to invest on icts and engage in e-business. • lack of training and trained manpower: smes lack enough romanian statistical review nr. / training on application of e-business technologies on smes, therefore internal resistance to move to e-business and uncertainties of the benefi ts of e-commerce are evident among smes, besides as it personnel in pakistan are limited, they normally work for large companies and smes can’t afford to recruit them and pay high salary. • security issues online payment through visa card: the security issues relating to access of visa card by the third party, or thrift from the hectares how illegally access to visa card number is also one cause that most of the people in south asia is not using the online payment through internet.. recommendations • establishment of cluster, location, etc. exclusively created and developed for smes to grow, having all the facilities (electricity • establishment of cluster, location etc. exclusively created and developed for sme to grow, having all the facilities (like electricity, gas road, internet etc) around bangladesh. • publication of white paper on small and medium scale enterprises each and every year ,which contains the detailed condition of smes and various plans and policies taken by government so that private sectors research can get the actual situation of smes. • smes should be highly integrated in forward and backward linkages and have presence in verses operations and productions. • e-commerce enabling rules and regulations should be established in bangladesh in line with japanese smes rule. • trainers can be hired from japan so that they can teach the involving parties in smes about the potential benefi ts of e-commerce and demonstrate how to do business online. • creation of congenial atmosphere for smes to grow and fl ourish. beside some activities are beyond the scope of private sectors and government intervention is a must .most desired governmental business security and promotion, provision for internet access etc moreover as smes have great impact on employment creation and contribution to gdp the responsibilities of the government are to promote smes by removing barriers and creating an e-commerce enabling environment to smes • the transfer of scientifi c and technological information from universities to smes is very much needed to make smes competitive and also to fi ll up the technological need .in japan such collaboration is very much need .in japan such collaboration is very much common. local industrial technology institutes , national and government industrial research revista română de statistică nr. / institutes are constantly and aggressively transferring technology to smes in bangladesh government can fund the project or technological help to smes .in bangladesh such collaboration is absent .so bangladesh government can fun the projects for technological help to smes through public and private universities. • telephone, mobile phone, internet computer and underlying application software technologies for e-business must have to be ensuring for the smes like japan .in addition, telecommunication sector should be deregulated and tale-density should be increased and internet should b made available both in town as well as in rural areas. besides government should take initiative to encourage the use of electronic payment system. government should ask and help the fi nancial institutions to introduce debit/credit cards and install atms all around the country. those infrastructures should be made available for smes use. • in bangladesh there is no proper it curriculum at the primary, high school and collage levels so the initiative of education board should be to design and introduce proper it based curriculum • as government is the large buyer so they can encourage smes for online transactions. moreover, government can provide services on the internet like e-procurmetn, e-fi lling of income taxes, online job searching online registration of exams and bringing all the library resources online. • the government should make effort to enhance the investment climate to attract and retain venture capital and investment in smes • government should apply lower tax rate on income of smes than to large fi rms and tax rebate should be given to smes for their fi rst few years of operation. • appropriate rules should be enacted to protect online customers from fraud an forger .besides, the government should educated people through media so that they feel comfortable to transat online conclusion small and medium scale enterprise have several advantages over large fi rms. they are much more fl exible, innovative and can adopt the changes in business environment very quickly .moreover in any developing countries like pakistan ,smes are much more important. pakistan categorized as low income country having some severe problems like employment, energy crisis, low per capita income, poverty, security derth and dependency on imported goods. smes can play a vital role for the development of economy of pakistan as well as create employment opportunities in the country. smes promote pro- romanian statistical review nr. / poor growth strategy and smes are evenly distributed all through the country, so promotion and development of smes will have impact on balanced regional development. bibliography - ahmed, m.u.( ). the small and medium enterprises (smes) in bangladesh an overview of the current status. - chau, p.y.k & tuchen, j.( ). a comparative study of business to consumer electronics commerce within the australian insurance sector. journal of information technology, : - . - currie, w. ( ). the global information society, john wiley and sons, chichester, uk. - oecd globalization small and medium enterprise smes vole country studies paris, france. - lation paul & pascale de b “the adopation of e-business technologies by smes - poon s. & swatman p. the internet for small businesses: an enabling infastucute fi fth internet society conference - scullery, a.b and woods w.a b b exchanges .the killer application in the business to business internet revolution harper collins new york . - sharma s.k wickramansinghe , n. and gupta jnd what should smes do to succeed in today knowledge-based econom (working paper) - thong j .resource constraints and information systems implementation in singaporean small business .omega pp - april . volume , number science american association for the advancement of science sciernce serves its i-eaders as a foruin for the lpitesentation and discussion of important issues lelated to the advancement of science, including the presentation of minority or conflicting point! of view, rather than by ptublishing only nmaterial on which a consensus has been reached. accoid- ingly, all articles pulblished in scienice-including editorials, news and comment, and book reviews -are signed anti leflect the individual views of the authors and not official points of view adopted bs the aaas ot- tic instituitions w ith sw hich the althoil s ar e afliliated editorial board alfel) ubroswn janies f. crown sewmoult s. kui f lisnik prfss flwsnk wv. i'uinamn n axine f- singer goridon wolnian h-l rut ri s. cguiowssky n. brucje hannay donald kennedy d)%nmi f. koshland, jr. donasiu) lindsli-s rutih pairick; rs-kyniond , ttio'apson editorial stalt editor i'hilitl h. abelson puiiblis%her blu siniess ma,aiage, w%iiiisu ti.v,\n llans nussbsuni mtaaging ediioo: r ot) rii v. ornses assistant editors: ellen e. murphy. john e. i n(l assistauns to the hosts nan(a tteiiourian p'siri( i ross e neuws adtl ( omzmient: johin wvalsh, luther j. caiuier, debiorath shapley, iroberr gillerte, nicho- las wade, constance holden, barbrra j. culliton. scherraine nmack rlesearuh newts: allen l. iianinioni), williamn f). nleiz, tiion.ss . msu(it. , jean l. nmarx, ariotiui l. ir irinson book review s: sylvia ebierh sri. ktit i ni is in(siotn, ann o'briln coi er eflitor: gkrayce fingeit edlitoricl as.i.tstunts: nma rgare'i allen, iswella bouldin, blair burns, ninkie burns, eleanore b utz, iary dorfman, judith givelber, corrine harris, nancy hartnagel, oliver heatwole, chirisiine karlik, gina bari kolata, margaret lloed, eric poggenpohl, jean rockwood, leah rn an, lois schnutt, michael schwartz, richard sfn iklosf, ya - swigart, eleanor warner c,ide to scititifit ml.strumoents: iichard sommter .vlemuber stip rectt oit'llntt: gwslndolyn huddle; .sub.sriptioti tot i, intlrieosn et records: ann g t %i n ) ad%ertising staff d)ire clor production manaager eari. j. slleraso marga.rei sieisling adl eti.siig sale.s malutagert iichard l. chairli s sailes: nlev \ork. n.y. : herbeit l. buiikiund. w. st. ( -pe- - ); sco ch plains, n.j. ( : c. rticlhai-d callis, unami lane ( - - ); chicago, ill. : jack ryan, roomn , n. micliigan ave. ( -de- - ); bev- erly hills, calif. : winn nance, it n. la cienega blvd. ( - - ) editoriial correspondence: massa- chusetts ave., nw, washington. d.c. . phones: (area code ) central office: - ; book re- views: - ; business office: - ; circula- tion: - ; cuide to scientific instruments: - ; news and comment: - ; reprints and permissions: - ; research news: - ; reviewing: - . cable: advancesci, washington. copies of "insti-uctions for contributors" can be obtained fionm the editorial office. see also page xv, science, march . advertising corre- spondence: room , w. st., new york, n.y. . phone: -pe- - . gasoline recently, professor marvin paul of the city colleges of chicago sug- gested to scienice that we devote an entire issue to energy. the idea was received with skepticism, but consultation with readers scattered across the united states caused lis to proceed. the decision was taken febru- ary . publication of the issue at this time was made possible by unl- usually good cooperation of both contributors and staff. the content of this issue was chosen to present material relevant to important public decisions of the next few years. some such topics have been recently treated in science: and repetition here was unwarranted. other topics will be dealt with later. one important matter not covered specifically in the following articles is gasoline and the automobile. special notice seems desirable, for those long lines at the service stations are telling us something. when people are willing to appear at a.m. at a station that is not scheduled to open until a.m., they convey a message about the importance that many people attach to their automobiles. in part the attachment is economic. to many people, auto transportation is essential to their livelihood. in part the attachment is emotional, as kenneth boulding suggests in an article in this issue. whatever the source of the demand, it would be politically impossible to force people this summer to get along on sup- plies as limited as those of februlary . in future years as people adjust, as they change to vehicles consuming less gasoline, the ac- ceptable level of supplies m,ay drop. for this year and probably the next few years, a minimum acceptable daily consumption averaged over the whole year is about . million barrels a day or about percent less than we consumed in . such a level would entail tension and grulmbling. with present-day refinery practice, a demand of . million barrels a day for gasoline fixes a minimum value for the input of crude oil. in typical instances, percent of the crude petroleum is converted to gtasoline. thus to supply the minimum demand for gasoline, something like million barrels of petroleum must be processed. our total con- sumption of oil and its products has been averaging about million barrels a day and our total production of crude oil and condensate has been about million barrels a day. these figures indicate the central importance of gasoline consumnption in dictating needs for crude oil. they also show that, in order merely to obtain enough gasoline, large quantities of gasoline or crude oil must be imported. there are, of course, other important uses of the gasoline chemicals in oil that will increase the lower limit on our need for oil. because of the central role of gasoline in energy problems, especial ef- forts should be made both to decrease demand and increase supply. had we been driving smaller, less gas-consuming cars, there would have been no energy crisis. some other forms of transportation consume less gasoline, and their use should be encouraged. in principle, the oil companies could increase the yield of gasoline from crude oil. this woulld require changes in refineries. today about percent of the energy of crude oil is used in providing heat for the refining processes. in principle, this heat could be furnished by coal. through more intense input of hydrogen in the cracking process, larger yields of gasoline could be obtained. one refinery expert has guessed that yields might be raised to as high as percent from the present percent. such a shift would entail other shifts in the produlct patterns and in the consumption of hydrocarbons. the barriers to increased yields are costs and time, but these can and should be overcome. petroleum is too important to be used merely as a source of heat.-philip h. abelson * for a list of seleted material rclated to energy that has appeared in .scienice. see page of this isstue. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ gasoline philip h. abelson doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the trademark of aaas. is a registeredscienceadvancement of science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for thescience by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ raw materials econstor make your publications visible. a service of zbw leibniz-informationszentrum wirtschaft leibniz information centre for economics hamburg institute of international economics (hwwa) (ed.) article — digitized version raw materials: aiec — a new cartel? intereconomics suggested citation: hamburg institute of international economics (hwwa) (ed.) ( ) : raw materials: aiec — a new cartel?, intereconomics, issn - , verlag weltarchiv, hamburg, vol. , iss. , pp. , http://dx.doi.org/ . /bf this version is available at: http://hdl.handle.net/ / standard-nutzungsbedingungen: die dokumente auf econstor dürfen zu eigenen wissenschaftlichen zwecken und zum privatgebrauch gespeichert und kopiert werden. sie dürfen die dokumente nicht für öffentliche oder kommerzielle zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. sofern die verfasser die dokumente unter open-content-lizenzen (insbesondere cc-lizenzen) zur verfügung gestellt haben sollten, gelten abweichend von diesen nutzungsbedingungen die in der dort genannten lizenz gewährten nutzungsrechte. terms of use: documents in econstor may be saved and copied for your personal and scholarly purposes. you are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public. if the documents have been made available under an open content licence (especially creative commons licences), you may exercise further usage rights as specified in the indicated licence. www.econstor.eu comments energy conference fruitless talks a f t e r nine days of negotiations the paris prelim- inary conference, convened to fix the number of participants to, the place, and the agenda of the planned energy summit between oil producing, oil consuming, and developing countries, ended without result in mid-april. right from the start there was a confrontation between two diametri- cally opposed basic opinions. the industrialised countries held the view that the negotiations should be confined to energy problems and re- lated issues and warned of one of those mam- moth jamborees with endless disputes and meagre results. contrary to this the mineral oil producing and the developing countries were not willing to content themselves with an oil con- ference but insisted in putting all raw materials as well as questions of development aid on the agenda. that the failure of the conference did not evoke much distress in the industrialised countries did not come as a surprise since the energy crisis seems to have lost much of its urgency: there is plenty of oil available, the oil producers' cartel has shown first indications of a break-up, and the recycling of the petro-dollars has so far refuted the gloomy predictions of a financial drying-up of the industrial nations. this, however, means also a deterioration of the other raw material pro- ducers' chances to obtain, with the support of the oil countries, a new price system for their own products and to establish a new world eco- nomic order according to the principles passed by the majority of delegates to the un general assembly. notwithstanding their present, rela- tively strong, position the industrialised countries would, however, be ill-advised to leave it at that until further notice. the energy situation could soon change again and in the long run they will in any case have to concede a larger share of the world's wealth to the raw material producing countries, ch. raw materials a i e c - a n e w cartel? eleven states meeting in geneva have decided to form an association of iron ore exporting countries (aiec) with headquarters in london. the initiators, on the one hand, stressed that their organisation was not to operate as a cartel but, on the other hand, the association shall help above all to bring about better trading conditions and higher export prices. australia, india, peru, sierra leone, sweden and venezuela are among the aiec's members. the ussr, the usa, canada and the p.r. china - ac- counting together for more than half the world's iron ore production of mn tons in - are staying outside. whether brazil, one of the major exporting countries, will join an "ore cartel" is very much in doubt: its government aims at doub- ling production and expanding exports; a clash of interests would be inevitable if the "ore club" felt tempted to hold up prices by tightening supplies. in view of the fact that the most important pro- ducers and some of the major exporting countries as well are so far standing apart from the aiec, it does not look probable that an opec-like iron ore cartel will come into being. aiec is more likely to remain a consultative body without in- cisive powers. the conference chairman, the indian minister chattopadhyaya, said that the association would demonstrate the ability of the exporting states to defend their "legitimate" inter- ests without violating the interests of the con- sumers. but conflicts will probably be avoided only as long as one side accepts as "legitimate" what the other side deems to be "legitimate". iwe. taiwan the death of the generalissimo chiang kai-shek, the man whom sun yat-sen, the father of modern china, saw as his successor, is dead. little had been heard of him since the u-turn in us policy to china. it was as long ago as that the then young officer came into contact with the nationalist and social reformer sun yat-sen, and when sun and his national people's party, the kuomintang, in suc- ceeded in forming a government, chiang was a member of it. by that time the kuomintang had developed into a movement set to rally the whole nation. amongst others it included the communist party of china which had been founded in . after sun yat-sen's death chiang soon emerged as the leader of the kuomintang. he surrounded himself at first with many leftist advisers, amongst them chou en-lai who became his chief of staff. in however chiang unexpectedly broke with the communists. the kuomintang government was made up of politicians of moderate views. in the decades which have elapsed since, the duel between chiang and mao has dominated the po- litical scene inside china and engaged the in- terest of the world. often it seemed that chiang was close to final victory, but later the fortunes of war turned forever: chiang with two millions intereconomics, no. , nanosheets of cuco o as a high-performance electrocatalyst in urea oxidation applied sciences article nanosheets of cuco o as a high-performance electrocatalyst in urea oxidation camila zequine , fangzhou wang , xianglin li , deepa guragain , s.r. mishra , k. siam , p. k. kahol and ram k. gupta , ,* department of chemistry, pittsburg state university, pittsburg, ks , usa; camilazequine@hotmail.com (c.z.); ksiam@pittstate.edu (k.s.) department of mechanical engineering, university of kansas, lawrence, ks , usa; fangzhouwang@ku.edu (f.w.); xianglinli@ku.edu (x.l.) department of physics and materials science, the university department of physics and materials science, the university of memphis, memphis, tn , usa; ddeepag @gmail.com (d.g.); srmishra@memphis.edu (s.r.m.) department of physics, pittsburg state university, pittsburg, ks , usa; pkahol@pittstate.edu kansas polymer research center, pittsburg state university, pittsburg, ks , usa * correspondence: ramguptamsu@gmail.com; tel.: + - - received: january ; accepted: february ; published: february ���������� ������� abstract: the urea oxidation reaction (uor) is a possible solution to solve the world’s energy crisis. fuel cells have been used in the uor to generate hydrogen with a lower potential compared to water splitting, decreasing the costs of energy production. urea is abundantly present in agricultural waste and in industrial and human wastewater. besides generating hydrogen, this reaction provides a pathway to eliminate urea, which is a hazard in the environment and to people’s health. in this study, nanosheets of cuco o grown on nickel foam were synthesized as an electrocatalyst for urea oxidation to generate hydrogen as a green fuel. the synthesized electrocatalyst was characterized using x-ray diffraction, scanning electron microscopy, and x-ray photoelectron spectroscopy. the electroactivity of cuco o towards the oxidation of urea in alkaline solution was evaluated using electrochemical measurements. nanosheets of cuco o grown on nickel foam required the potential of . v in m koh with . m urea to deliver a current density of ma/cm . the cuco o electrode was electrochemically stable for over h of continuous measurements. the high catalytic activities for the hydrogen evolution reaction make the cuco o electrode a bifunctional catalyst and a promising electroactive material for hydrogen production. the two-electrode electrolyzer demanded a potential of . v, which was mv less than that for the urea-free counterpart. our study suggests that the cuco o electrode can be a promising material as an efficient uor catalyst for fuel cells to generate hydrogen at a low cost. keywords: urea oxidation reaction; fuel cells; cyclic voltammetry; hydrogen production . introduction in recent years, the utilization of urea as an alternative fuel in fuel cells has grown significantly, since it is highly available, stable, and nonflammable [ ]. fuel cells are devices that convert chemical energy into electrical energy, playing a vital role in overcoming the world energy crisis [ , ]. urea is an abundant waste generated in agricultural land, and it is present in industrial and human wastewater as well. urea is produced from natural gas or can be synthesized from ammonia. when in contact with atmosphere and groundwater, urea breaks down into ammonia and nitrate, causing health and environmental problems [ – ]. a solution to eliminate these problems caused by urea, and to appl. sci. , , ; doi: . /app www.mdpi.com/journal/applsci http://www.mdpi.com/journal/applsci http://www.mdpi.com https://orcid.org/ - - - https://orcid.org/ - - - http://www.mdpi.com/ - / / / ?type=check_update&version= http://dx.doi.org/ . /app http://www.mdpi.com/journal/applsci appl. sci. , , of also generate clean energy, is the urea oxidation reaction (uor) [ ]. this reaction is described as follows [ , ]: co(nh ) + h o → n + h + co ( ) thermodynamically, water splitting occurs at . v to generate hydrogen, while urea oxidation could provide hydrogen at a lower potential of . v [ , ]. this means that urea oxidation provides cheaper hydrogen production than water electrolysis. in previous reports, it is common to see the intense utilization of nickel-based catalysts to oxidize urea efficiently at low overpotential [ , , ]. forslund et al. reported a study on the use of lanio as a catalyst for the electrooxidation of urea in alkaline conditions [ ]. the nonstoichiometric spinel structure ni . mn . o synthesized by periyasamy et al., using a hydrothermal synthesis process, showed excellent electrochemical properties with the highest activity toward electro-oxidation of urea in alkaline solutions [ ]. the development of porous ni n nanosheet arrays on carbon cloth studied by liu et al. also showed high performance and was a durable electrocatalyst for urea oxidation [ ]. a possibility to use the same principles, but with a different component, led us to develop and produce copper-based catalysts that can oxidize urea efficiently to improve the properties of fuel cells. electrode materials made of transition metal oxides are often used as electrocatalysts because of their high electrochemical performance, natural abundance, and low cost. in addition, copper and cobalt salts are considered a promising electrode material for energy generation and storage devices due to its nontoxicity and high electrical conductivity. zheng et al. have shown that cobalt-based compounds are excellent for hydrogen adsorption [ ]. mesostructured cuco s /cuco o nanoflowers were synthesized by xu et al. and showed an excellent electrochemical performance for energy applications [ ]. an asymmetric supercapacitor based on cuco s /cuco o as the cathode and graphene aerogel as the anode delivered a high energy density of . wh/kg and power density of . kw/kg. tong et al. used nimoo nanosheets to study the performance in the urea oxidation reaction. they found a larger number of exposed active sites, faster electron transport, and lower adsorption energy of urea molecules. comparing the cyclic voltammetry (cv) curve recorded in koh solution, the anodic current density of nimoo increased largely after adding urea, demonstrating its high catalytic response activity for electro-oxidation of urea [ ]. as reported by wu et al., a nickel hydroxide electrode with nanocup architecture offered better electrocatalytic performance during electrolysis of urea [ ]. nickel oxide−nickel hybrid nanoarrays on nickel foam (nio−ni/nf) was studied by yue et al. for water splitting and urea oxidation [ ]. the electrode showed excellent activity for urea oxidation with the need of a low potential in . m koh with . m urea. ji et al. reported that open-ended α-ni(oh) nanotubes provided effective surface area and active sites when exposed to an electrolyte for urea electrolysis, ensuring a much higher current density during urea electrolysis [ ]. hence, in this work, cuco o was synthesized by the hydrothermal method, and the electrocatalytic activity was studied for the oxidation of urea. materials with three-dimensional ( d) architectures are attractive because their high surface area provides many active sites, and, thus, better electron transfer. the material studied in this report is a d flower-like structure composed of cuco o nanosheets, which showed excellent electrochemical properties with a high activity. . experimental details . . preparation of cuco o on ni foam the cuco o was synthesized on ni foam using a one-pot hydrothermal method followed by an annealing process. a piece of ni foam was cleaned with m hcl solution in an ultrasound bath to remove the nio layer on the surface, and was then washed with deionized water several times. in a typical synthesis, mg of co(no ) . h o, . mg of cu(no ) . h o, and mg of urea were dissolved in ml of ethanol. the solution was transferred to a ml teflon autoclave reactor along with the pre-cleaned ni foam and maintained at ◦c for h. after cooling to room temperature, the ni foam was washed with water and dried under vacuum at ◦c overnight. finally, in order to appl. sci. , , of obtain cuco o on the ni foam, the sample was annealed at ◦c with a temperature ramp rate of ◦c/min for h in an air atmosphere to obtain cuco o (figure ). obtain cuco o on the ni foam, the sample was annealed at oc with a temperature ramp rate of oc/min for h in an air atmosphere to obtain cuco o (figure. ). . . structural characterization the structural identity, phase purity, and physical morphology of the fabricated electrode were analyzed using x-ray diffraction (xrd), fei versa d dual beam scanning electron microscopy (sem), fei tecnai f xt field emission transmission electron microscope (tem), and phi versaprobe ii x-ray photoelectron spectroscopy (xps). cukα (λ= . Å) radiation was used to record the x-ray diffraction patterns in θ-θ mode. . . electrochemical characterization to evaluate the catalytic activity of cuco o and investigate the function of oh- ions in the electro-oxidation of urea, cyclic voltammetry (cv) was performed in m koh solution containing . m urea. these measurements were performed using the standard three-electrode method. a versastat - electrochemical workstation (princeton applied research, usa) was used for all electrochemical measurements. a platinum wire and a saturated calomel electrode were used as a counter and a reference electrode, respectively. the synthesized sample on nickel foam was used as the working electrode. figure . illustration of the formation of cuco o on ni foam. . results and discussion . . structural characterization x-ray diffraction analysis confirmed a high phase purity of the synthesized cuco o , as seen in figure a. all of the diffraction peaks matched well with the jcpds card no. - , which corresponded to the pure cubic spinel phase of cuco o with a lattice parameter value of a = . Ǻ [ , ]. scanning electron microscopy was employed to investigate the sample morphologically. high-magnification sem images confirmed that cuco o was uniformly grown on ni foam, with a flower-shaped structure composed of nanosheets in different orientations and a smooth surface, revealing a three-dimensional porous structure (figure b). this uniform flower-shaped structure may have been the result of the faradic reaction. the average diameter of the flower structure was about µm, and it was interconnected with the nanosheets that had a thickness of nm. tem images of cuco o powder scraped from the ni foam at various magnifications are shown in figure . tem images reveal nanorod-like structures with good crystallinity. x-ray photoelectron spectroscopy of the cuco o is shown in figure . the xps survey spectra confirmed the presence of copper, cobalt, oxygen, and carbon elements (figure a). the high-resolution xps spectrum for cu p showed the existence of p / and p / peaks of copper (figure b) [ , ]. the high-resolution xps spectrum for co p is shown in figure c. the two main peaks of co p / and co p / were observed around . and . ev, respectively, suggesting the existence of both co + and co + [ , ]. considering the co p peak shape, this was consistent with spectra of co o standards given by gu et al. [ ] and yang et al. [ ]. these studies showed a p / peak binding energy of . ev and a broad plateau-like satellite structure to higher binding energies between the p / and p / peaks. the figure . illustration of the formation of cuco o on ni foam. . . structural characterization the structural identity, phase purity, and physical morphology of the fabricated electrode were analyzed using x-ray diffraction (xrd), fei versa d dual beam scanning electron microscopy (sem), fei tecnai f xt field emission transmission electron microscope (tem), and phi versaprobe ii x-ray photoelectron spectroscopy (xps). cukα (λ = . Å) radiation was used to record the x-ray diffraction patterns in θ-θ mode. . . electrochemical characterization to evaluate the catalytic activity of cuco o and investigate the function of oh- ions in the electro-oxidation of urea, cyclic voltammetry (cv) was performed in m koh solution containing . m urea. these measurements were performed using the standard three-electrode method. a versastat - electrochemical workstation (princeton applied research, usa) was used for all electrochemical measurements. a platinum wire and a saturated calomel electrode were used as a counter and a reference electrode, respectively. the synthesized sample on nickel foam was used as the working electrode. . results and discussion . . structural characterization x-ray diffraction analysis confirmed a high phase purity of the synthesized cuco o , as seen in figure a. all of the diffraction peaks matched well with the jcpds card no. - , which corresponded to the pure cubic spinel phase of cuco o with a lattice parameter value of a = . . . structural characterization the structural identity, phase purity, and physical morphology of the fabricated electrode were analyzed using x-ray diffraction (xrd), fei versa d dual beam scanning electron microscopy (sem), fei tecnai f xt field emission transmission electron microscope (tem), and phi versaprobe ii x-ray photoelectron spectroscopy (xps). cukα (λ= . Å) radiation was used to record the x-ray diffraction patterns in θ-θ mode. . . electrochemical characterization to evaluate the catalytic activity of cuco o and investigate the function of oh- ions in the electro-oxidation of urea, cyclic voltammetry (cv) was performed in m koh solution containing . m urea. these measurements were performed using the standard three-electrode method. a versastat - electrochemical workstation (princeton applied research, usa) was used for all electrochemical measurements. a platinum wire and a saturated calomel electrode were used as a counter and a reference electrode, respectively. the synthesized sample on nickel foam was used as the working electrode. figure . illustration of the formation of cuco o on ni foam. . results and discussion . . structural characterization x-ray diffraction analysis confirmed a high phase purity of the synthesized cuco o , as seen in figure a. all of the diffraction peaks matched well with the jcpds card no. - , which corresponded to the pure cubic spinel phase of cuco o with a lattice parameter value of a = . Ǻ [ , ]. scanning electron microscopy was employed to investigate the sample morphologically. high-magnification sem images confirmed that cuco o was uniformly grown on ni foam, with a flower-shaped structure composed of nanosheets in different orientations and a smooth surface, revealing a three-dimensional porous structure (figure b). this uniform flower-shaped structure may have been the result of the faradic reaction. the average diameter of the flower structure was about µm, and it was interconnected with the nanosheets that had a thickness of nm. tem images of cuco o powder scraped from the ni foam at various magnifications are shown in figure . tem images reveal nanorod-like structures with good crystallinity. x-ray photoelectron spectroscopy of the cuco o is shown in figure . the xps survey spectra confirmed the presence of copper, cobalt, oxygen, and carbon elements (figure a). the high-resolution xps spectrum for cu p showed the existence of p / and p / peaks of copper (figure b) [ , ]. the high-resolution xps spectrum for co p is shown in figure c. the two main peaks of co p / and co p / were observed around . and . ev, respectively, suggesting the existence of both co + and co + [ , ]. considering the co p peak shape, this was consistent with spectra of co o standards given by gu et al. [ ] and yang et al. [ ]. these studies showed a p / peak binding energy of . ev and a broad plateau-like satellite structure to higher binding energies between the p / and p / peaks. the high-resolution spectrum for o s is shown in figure d, which shows two peaks centered at . and . ev, respectively. the peak around . ev corresponded to metal–oxygen bonding, while [ , ]. scanning electron microscopy was employed to investigate the sample morphologically. high-magnification sem images confirmed that cuco o was uniformly grown on ni foam, with a flower-shaped structure composed of nanosheets in different orientations and a smooth surface, revealing a three-dimensional porous structure (figure b). this uniform flower-shaped structure may have been the result of the faradic reaction. the average diameter of the flower structure was about µm, and it was interconnected with the nanosheets that had a thickness of nm. tem images of cuco o powder scraped from the ni foam at various magnifications are shown in figure . tem images reveal nanorod-like structures with good crystallinity. x-ray photoelectron spectroscopy of the cuco o is shown in figure . the xps survey spectra confirmed the presence of copper, cobalt, oxygen, and carbon elements (figure a). the high-resolution xps spectrum for cu p showed the existence of p / and p / peaks of copper (figure b) [ , ]. the high-resolution xps spectrum for co p is shown in figure c. the two main peaks of co p / and co p / were observed around . and . ev, respectively, suggesting the existence of both co + and co + [ , ]. considering the co p peak shape, this was consistent with spectra of co o standards given by gu et al. [ ] and yang et al. [ ]. these studies showed a p / peak binding energy of . ev and a broad plateau-like satellite structure to higher binding energies between the p / and p / peaks. the high-resolution spectrum for o s is shown in figure d, which shows two peaks centered at . and . ev, appl. sci. , , of respectively. the peak around . ev corresponded to metal–oxygen bonding, while the second peak corresponded to a high number of defect sites with low oxygen coordination in the material with a small particle size [ ]. high-resolution spectrum for o s is shown in figure d, which shows two peaks centered at . and . ev, respectively. the peak around . ev corresponded to metal–oxygen bonding, while the second peak corresponded to a high number of defect sites with low oxygen coordination in the material with a small particle size [ ]. figure . (a) xrd pattern and (b) sem image of cuco o . figure . tem images of cuco o at various magnifications. cu p co p c s binding energy (ev) in te n s it y ( a .u .) o s [a] cu + cu+ cu + cu + in te n s it y ( a .u .) binding energy (ev) [b] in te n s it y ( a .u .) θ (degree) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) [a] figure . (a) xrd pattern and (b) sem image of cuco o . high-resolution spectrum for o s is shown in figure d, which shows two peaks centered at . and . ev, respectively. the peak around . ev corresponded to metal–oxygen bonding, while the second peak corresponded to a high number of defect sites with low oxygen coordination in the material with a small particle size [ ]. figure . (a) xrd pattern and (b) sem image of cuco o . figure . tem images of cuco o at various magnifications. cu p co p c s binding energy (ev) in te n s it y ( a .u .) o s [a] cu + cu+ cu + cu + in te n s it y ( a .u .) binding energy (ev) [b] in te n s it y ( a .u .) θ (degree) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) [a] figure . tem images of cuco o at various magnifications. high-resolution spectrum for o s is shown in figure d, which shows two peaks centered at . and . ev, respectively. the peak around . ev corresponded to metal–oxygen bonding, while the second peak corresponded to a high number of defect sites with low oxygen coordination in the material with a small particle size [ ]. figure . (a) xrd pattern and (b) sem image of cuco o . figure . tem images of cuco o at various magnifications. cu p co p c s binding energy (ev) in te n s it y ( a .u .) o s [a] cu + cu+ cu + cu + in te n s it y ( a .u .) binding energy (ev) [b] in te n s it y ( a .u .) θ (degree) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) [a] figure . cont. appl. sci. , , of figure . xps spectra of the cuco o : (a) full survey spectra, (b) cu p spectrum, (c) co p spectrum, and (d) o s spectrum. . . electrocatalytic activities the electrocatalytic activities of the cuco o electrode were examined using a three-electrode setup in m koh, without and with . m urea. as seen in figure a, the anodic current density of cuco o increased significantly after the addition of urea, confirming a high catalytic activity response of cuco o for the electro-oxidation of urea. the cuco o electrode demanded a potential of . v to deliver a current density of ma/cm , which was much lower than that without urea. the potential required to deliver ma/cm using the cuco o electrode was among the more favorable reported values. for example, the ni(oh) nanosheet and nanocube required a potential of . v and . v, respectively, to produce a current density of ma/cm [ , ]. ni p, rhodium- ni, and nimo nanosheets demanded a potential . v, . v, and . v, respectively, to generate a current density of ma/cm [ – ]. the tafel slope for the cuco o electrode was calculated using polarization data, and was observed to be and mv/dec in m koh without and with . m urea, respectively (figure b). the lower tafel slope in the urea solution indicated faster catalytic kinetic energy for the cuco o electrode. figure . (a) cyclic voltammetry curves in m koh with and without . m urea, and (b) corresponding tafel slopes. furthermore, the urea oxidation kinetics were investigated by electrochemical impedance spectroscopy (eis). the nyquist plots for the cuco o electrode at various potentials are given in figure s . as seen in the nyquist plots, cuco o had a low impedance and, thus, markedly fast kinetics toward urea electro-oxidation. furthermore, the behavior of the nyquist plots depended on co + co + co + in te n s it y ( a .u .) binding energy (ev) [c] co + o in te n s it y ( a .u .) binding energy (ev) o [d] . . . . . . - cuco o cuco o + urea c u rr e n t d e n s it y ( m a /c m ) potential (v, rhe) [a] . . . . . . . mv/dec p o te n ti a l (v , r h e ) cuco o cuco o + urea current density (ma/cm ) mv/dec [b] figure . xps spectra of the cuco o : (a) full survey spectra, (b) cu p spectrum, (c) co p spectrum, and (d) o s spectrum. . . electrocatalytic activities the electrocatalytic activities of the cuco o electrode were examined using a three-electrode setup in m koh, without and with . m urea. as seen in figure a, the anodic current density of cuco o increased significantly after the addition of urea, confirming a high catalytic activity response of cuco o for the electro-oxidation of urea. the cuco o electrode demanded a potential of . v to deliver a current density of ma/cm , which was much lower than that without urea. the potential required to deliver ma/cm using the cuco o electrode was among the more favorable reported values. for example, the ni(oh) nanosheet and nanocube required a potential of . v and . v, respectively, to produce a current density of ma/cm [ , ]. ni p, rhodium-ni, and nimo nanosheets demanded a potential . v, . v, and . v, respectively, to generate a current density of ma/cm [ – ]. the tafel slope for the cuco o electrode was calculated using polarization data, and was observed to be and mv/dec in m koh without and with . m urea, respectively (figure b). the lower tafel slope in the urea solution indicated faster catalytic kinetic energy for the cuco o electrode. figure . xps spectra of the cuco o : (a) full survey spectra, (b) cu p spectrum, (c) co p spectrum, and (d) o s spectrum. . . electrocatalytic activities the electrocatalytic activities of the cuco o electrode were examined using a three-electrode setup in m koh, without and with . m urea. as seen in figure a, the anodic current density of cuco o increased significantly after the addition of urea, confirming a high catalytic activity response of cuco o for the electro-oxidation of urea. the cuco o electrode demanded a potential of . v to deliver a current density of ma/cm , which was much lower than that without urea. the potential required to deliver ma/cm using the cuco o electrode was among the more favorable reported values. for example, the ni(oh) nanosheet and nanocube required a potential of . v and . v, respectively, to produce a current density of ma/cm [ , ]. ni p, rhodium- ni, and nimo nanosheets demanded a potential . v, . v, and . v, respectively, to generate a current density of ma/cm [ – ]. the tafel slope for the cuco o electrode was calculated using polarization data, and was observed to be and mv/dec in m koh without and with . m urea, respectively (figure b). the lower tafel slope in the urea solution indicated faster catalytic kinetic energy for the cuco o electrode. figure . (a) cyclic voltammetry curves in m koh with and without . m urea, and (b) corresponding tafel slopes. furthermore, the urea oxidation kinetics were investigated by electrochemical impedance spectroscopy (eis). the nyquist plots for the cuco o electrode at various potentials are given in figure s . as seen in the nyquist plots, cuco o had a low impedance and, thus, markedly fast kinetics toward urea electro-oxidation. furthermore, the behavior of the nyquist plots depended on co + co + co + in te n s it y ( a .u .) binding energy (ev) [c] co + o in te n s it y ( a .u .) binding energy (ev) o [d] . . . . . . - cuco o cuco o + urea c u rr e n t d e n s it y ( m a /c m ) potential (v, rhe) [a] . . . . . . . mv/dec p o te n ti a l (v , r h e ) cuco o cuco o + urea current density (ma/cm ) mv/dec [b] figure . (a) cyclic voltammetry curves in m koh with and without . m urea, and (b) corresponding tafel slopes. furthermore, the urea oxidation kinetics were investigated by electrochemical impedance spectroscopy (eis). the nyquist plots for the cuco o electrode at various potentials are given in figure s . as seen in the nyquist plots, cuco o had a low impedance and, thus, markedly fast kinetics toward urea electro-oxidation. furthermore, the behavior of the nyquist plots depended appl. sci. , , of on the potential. with the increase in the potential, the diameter of the semicircle was decreased, suggesting a lowering in charge transfer resistance. an important method to evaluate the long-term stability of the obtained electrodes in urea oxidation is the chronoamperometric response test. figure s shows the superior catalytic stability with low degradation in current density after h. from this measurement, it was observed that cuco o exhibited a stable and durable catalytic performance. the cv curves of the cuco o electrode in m koh electrolyte with . m urea was measured at various scan rates. figure s shows the variation of measured potential versus scan rates determined using cv data at ma/cm . as seen in figure s , the cuco o electrode showed almost no change in potential during cv measurements at various scan rates, indicating superior rate capability for the uor process. tests performed by shi et al. demonstrated an increase in the anodic current density for the ni/mo/graphene nanocatalysts after addition of urea in the system [ ]. this increase was also found by barakat et al. in the urea oxidation test for ni and mn nanoparticle-decorated carbon nanofibers [ ]. sodium nickel fluoride nanocubes were studied by kakati et al. in different concentrations of urea for its oxidation [ ]. it was found that the peak potentials of urea oxidation increased linearly with increasing urea concentration. zeng et al. studied the effect in nico layered double hydroxide for promoted electrocatalytic urea oxidation, which proved to be efficient, showing a low onset potential and a high faraday efficiency [ ]. the electrocatalytic performance of the cuco o electrode for hydrogen evolution reaction (her) was also studied. figure a shows the polarization curves for a cuco o electrode in m koh, without and with . m urea. as observed, the polarization curves were overlapping each other, indicating the little impact that urea had on the electrochemical activity of the cuco o electrode in the her region. the cuco o electrode required a potential of mv to generate ma/cm . the tafel slope for the cuco o electrode in m koh without and with urea was observed to be and mv/dec, respectively, suggesting no change in the kinetics for the her process after addition of urea (figure b). liu et al. have reported a tafel slope of and mv/dec for ni n and ni(oh) nanosheets on carbon cloth in m koh + . m urea solution [ ]. the efficiency (η) for the urea electrolysis can be estimated by the following expression [ ]: η = it − ioer it × % ( ) where it is the overall current density during electrolysis of urea ( m koh + . m urea) and the ioer is the current density of oer process in m koh at s (figure s ). an efficiency of % was observed for the cuco o electrode. the potential. with the increase in the potential, the diameter of the semicircle was decreased, suggesting a lowering in charge transfer resistance. an important method to evaluate the long-term stability of the obtained electrodes in urea oxidation is the chronoamperometric response test. figure s shows the superior catalytic stability with low degradation in current density after h. from this measurement, it was observed that cuco o exhibited a stable and durable catalytic performance. the cv curves of the cuco o electrode in m koh electrolyte with . m urea was measured at various scan rates. figure s shows the variation of measured potential versus scan rates determined using cv data at ma/cm . as seen in figure s , the cuco o electrode showed almost no change in potential during cv measurements at various scan rates, indicating superior rate capability for the uor process. tests performed by shi et al. demonstrated an increase in the anodic current density for the ni/mo/graphene nanocatalysts after addition of urea in the system [ ]. this increase was also found by barakat et al. in the urea oxidation test for ni and mn nanoparticle-decorated carbon nanofibers [ ]. sodium nickel fluoride nanocubes were studied by kakati et al. in different concentrations of urea for its oxidation [ ]. it was found that the peak potentials of urea oxidation increased linearly with increasing urea concentration. zeng et al. studied the effect in nico layered double hydroxide for promoted electrocatalytic urea oxidation, which proved to be efficient, showing a low onset potential and a high faraday efficiency [ ]. the electrocatalytic performance of the cuco o electrode for hydrogen evolution reaction (her) was also studied. figure a shows the polarization curves for a cuco o electrode in m koh, without and with . m urea. as observed, the polarization curves were overlapping each other, indicating the little impact that urea had on the electrochemical activity of the cuco o electrode in the her region. the cuco o electrode required a potential of mv to generate ma/cm . the tafel slope for the cuco o electrode in m koh without and with urea was observed to be and mv/dec, respectively, suggesting no change in the kinetics for the her process after addition of urea (figure b). liu et al. have reported a tafel slope of and mv/dec for ni n and ni(oh) nanosheets on carbon cloth in m koh + . m urea solution [ ]. the efficiency (η) for the urea electrolysis can be estimated by the following expression [ ]:  = 𝑖 − 𝑖𝑖 × % ( ) where it is the overall current density during electrolysis of urea ( m koh + . m urea) and the ioer is the current density of oer process in m koh at s (figure s ). an efficiency of % was observed for the cuco o electrode. figure . (a) linear sweep voltammetry (lsv) curves of the cuco o electrode toward her in . m koh with . m urea, and (b) corresponding tafel plots. the electrocatalytic activities of the cuco o electrode were further examined in a two-electrode electrolyzer configuration. the cuco o electrode was used as the anode for the uor and the - . - . - . . . . - - - - - - cuco o cuco o + ureac u rr e n t d e n s it y ( m a /c m ) potential (v, rhe) [a] - . - . - . . mv/dec cuco o cuco o + urea p o te n ti a l (v , r h e ) current density (ma/cm ) mv/dec [b] figure . (a) linear sweep voltammetry (lsv) curves of the cuco o electrode toward her in . m koh with . m urea, and (b) corresponding tafel plots. appl. sci. , , of the electrocatalytic activities of the cuco o electrode were further examined in a two-electrode electrolyzer configuration. the cuco o electrode was used as the anode for the uor and the cathode for the her process in alkaline media. figure a shows polarization curves of the two-electrode electrolyzer in m koh, without and with . m urea. the electrolyzer required a cell voltage of . v to deliver a current density of ma/cm in urea solution, which was mv less than the cell voltage required without urea in the alkaline solution. the observed cell voltage was better than many other reported systems, such as ni(oh) -ni(oh) and pt/c-ruo [ ]. in addition, it had a performance in urea solution, and the cuco o electrode showed outstanding electrochemical durability (figure b). the chronopotentiometry test, performed for porous pomegranate-like ni/c in the urea oxidation reaction made by wang et al., had a stable performance over h [ ]. cathode for the her process in alkaline media. figure a shows polarization curves of the two- electrode electrolyzer in m koh, without and with . m urea. the electrolyzer required a cell voltage of . v to deliver a current density of ma/cm in urea solution, which was mv less than the cell voltage required without urea in the alkaline solution. the observed cell voltage was better than many other reported systems, such as ni(oh) -ni(oh) and pt/c-ruo [ ]. in addition, it had a performance in urea solution, and the cuco o electrode showed outstanding electrochemical durability (figure b). the chronopotentiometry test, performed for porous pomegranate-like ni/c in the urea oxidation reaction made by wang et al., had a stable performance over h [ ]. figure . (a) polarization curves for the cuco o electrode in m koh without and with . m urea, and (b) chronopotentiometric curve for the cuco o electrode. . conclusions in conclusion, it is possible to prove the two main advantages that the urea oxidation reaction can bring to the world: ( ) it is a solution to eliminate the urea from groundwater systems and the environment that are harmful to people, and ( ) the production of h uses less energy and has a lower cost, which helps to solve the energy crisis. cuco o grown on nickel foam was successfully synthesized, making it possible to utilize them as a highly efficient uor electrocatalyst under alkaline conditions. the high surface area favors charge transfer capacity and improves the reaction kinetics. the cv curves clearly show a significant decrease in potential after the addition of urea, which leads to cheaper hydrogen production. the two-electrode electrolyzer need a potential of . v, which is mv less than that for the urea-free counterpart. from the overall investigation, the results suggest that cuco o can be used in fuel cells for low-cost hydrogen generation. author contributions: r.k.g. conceived the project, designed the experiments, interpreted the data, and finalized the manuscript. the first draft of the manuscript was written by c.z. c.z. performed all the electrochemical measurements. f.w. and x.l. provided sem images, tem images, and xps data. all authors reviewed and commented on the manuscript. acknowledgments: dr. ram k. gupta expresses his sincere acknowledgment to the polymer chemistry program and the kansas polymer research center, pittsburg state university for providing financial and research support to complete this project. xl wants to thank the funding support from nsf ( ). sm thanks fit-drones and biologistic for the financial support. conflicts of interest: the authors declare no conflict of interest. references . . . . . c u rr e n t d e n s it y ( m a /c m ) voltage (v) cuco o cuco o + urea [a] . . . . p o te n ti a l (v ) time (h) [b] figure . (a) polarization curves for the cuco o electrode in m koh without and with . m urea, and (b) chronopotentiometric curve for the cuco o electrode. . conclusions in conclusion, it is possible to prove the two main advantages that the urea oxidation reaction can bring to the world: ( ) it is a solution to eliminate the urea from groundwater systems and the environment that are harmful to people, and ( ) the production of h uses less energy and has a lower cost, which helps to solve the energy crisis. cuco o grown on nickel foam was successfully synthesized, making it possible to utilize them as a highly efficient uor electrocatalyst under alkaline conditions. the high surface area favors charge transfer capacity and improves the reaction kinetics. the cv curves clearly show a significant decrease in potential after the addition of urea, which leads to cheaper hydrogen production. the two-electrode electrolyzer need a potential of . v, which is mv less than that for the urea-free counterpart. from the overall investigation, the results suggest that cuco o can be used in fuel cells for low-cost hydrogen generation. supplementary materials: the following are available online at http://www.mdpi.com/ - / / / /s , figure s : nyquist plots of cuco o , figure s : stability performance of the electrode using chronoamperometry, figure s : potential versus scan rates for cuco o electrode, figure s : chronoamperograms of cuco o electrode in m koh without and with . m urea. author contributions: r.k.g. conceived the project, designed the experiments, interpreted the data, and finalized the manuscript. the first draft of the manuscript was written by c.z. c.z. performed all the electrochemical measurements. f.w. and x.l. provided sem images, tem images, and xps data. all authors reviewed and commented on the manuscript. acknowledgments: ram k. gupta expresses his sincere acknowledgment to the polymer chemistry program and the kansas polymer research center, pittsburg state university for providing financial and research support to complete this project. xianglin li wants to thank the funding support from nsf ( ). s. r. mishra thanks fit-drones and biologistic for the financial support. conflicts of interest: the authors declare no conflict of interest. http://www.mdpi.com/ - / / / /s appl. sci. , , of references . periyasamy, s.; subramanian, p.; levi, e.; aurbach, d.; gedanken, a.; schechter, a. exceptionally active and stable spinel nickel manganese oxide electrocatalysts for urea oxidation reaction. acs appl. mater. interfaces , , . 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[crossref] [pubmed] © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . /j.elecom. . . http://dx.doi.org/ . /c ta k http://dx.doi.org/ . /s - - - http://dx.doi.org/ . /j.electacta. . . http://dx.doi.org/ . /j.electacta. . . http://dx.doi.org/ . /j.electacta. . . http://dx.doi.org/ . /acssuschemeng. b http://dx.doi.org/ . /acsami. b http://www.ncbi.nlm.nih.gov/pubmed/ http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	introduction 	experimental details 	preparation of cuco o on ni foam 	structural characterization 	electrochemical characterization 	results and discussion 	structural characterization 	electrocatalytic activities 	conclusions 	references world business trends econstor make your publications visible. a service of zbw leibniz-informationszentrum wirtschaft leibniz information centre for economics hamburg institute of international economics (hwwa) (ed.) article — digitized version world business trends intereconomics suggested citation: hamburg institute of international economics (hwwa) (ed.) ( ) : world business trends, intereconomics, issn - , verlag weltarchiv, hamburg, vol. , iss. , pp. - , http://dx.doi.org/ . /bf this version is available at: http://hdl.handle.net/ / standard-nutzungsbedingungen: die dokumente auf econstor dürfen zu eigenen wissenschaftlichen zwecken und zum privatgebrauch gespeichert und kopiert werden. sie dürfen die dokumente nicht für öffentliche oder kommerzielle zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. sofern die verfasser die dokumente unter open-content-lizenzen (insbesondere cc-lizenzen) zur verfügung gestellt haben sollten, gelten abweichend von diesen nutzungsbedingungen die in der dort genannten lizenz gewährten nutzungsrechte. terms of use: documents in econstor may be saved and copied for your personal and scholarly purposes. you are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public. if the documents have been made available under an open content licence (especially creative commons licences), you may exercise further usage rights as specified in the indicated licence. www.econstor.eu world business trends usa: bad growth prospects for d u r i n g the first quarter of the year the cyclical downswing in the usa was accelerating under the influence of the energy supply crisis. due to the season- al trend, gnp in real terms even declined by . p.c. (i.e. by a yearly rate of over p.c.). among the individual sectors the automotive industry was especially affected. but also in the manufacturing industry alto- gether the utilisation of capaci- ties has been decreasing more speedily since the beginning of the year. adjusted for seasonal variation the decline of industrial production (november until march: - . p.c.) did not con- tinue after the arab oil produc- ing countries had put an end to the oil embargo. decline of private demand as to demand, private con- sumption further decreased dur- ing the first quarter due to the strong upward tendency of prices. as a consequence of the energy crisis, capital ex- penditure on equipment declin- ed. private building again suffer- ed from the heaviest decrease. against this there was a further significant increase in industrial building. the american foreign trade position deteriorated as compared with the preceding quarter. in terms of value, im- ports showed a much steeper increase than exports. conse- quently, the balance of trade surplus diminished rapidly. in- crements of foreign trade are for the most part traceable to price increases. between sep- tember and march import ,prices - primarily because of the heavy increase of crude oil prices - had risen by p.c., export prices by p.c. steep price increases the domestic tendency of prices to rise has strengthened until spring. between january and april wholesale prices in- creased by a yearly rate of p.c. costs of living rose by a corresponding rate of p.c.; finally they exceeded those of the preceding year by . p.c. the heavy advance in prices of industrial consumer goods was to a great extent caused by the rise of petrol and fuel oil. stabi- lisation efforts were restricted to the federal reserve system's .policy of high interest rates. be- fore the administration aban- doned its income policy at the end of april, the price controls were gradually removed. the official controls had - at least during the second half of their almost three-years' employment - been nearly ineffectual in restraining the upward move- ment of prices and had only a one-sided dampening influence on the development of wages. now wages threaten to give new impulses for price increases. after the end of the controls, workers might raise their de- mands in order to compensate for their real income losses of the last months. since, however, prices for mineral oil products, food-stuffs and some industrial raw materials might exercise a dampening influence, prospects for a slight slowing-down of the inflationary process are not bad. tendencies towards economic recovery after the calming of the ener- gy crisis there will be a re- covery in several economic sec- tors. thus during the second index numbers of world market prices of foodstuff and industrial raw materials index and commodity group hwwa-indax * ( -- = ) foodstuffs raw materials other than foodstuffs . . . fuels raw materials for consumer goods .. raw materials for capital goods reuter'e index ( . . : ) moody's index ( . . - ) may i , , , , , , , s , august , , , , , , , , i november , , , , , , , , february , , , , , , , , i may , , , , , , , , may , , , , , , , , june , , , , , , , , index compiled by the hamburg institute for international eoonomlos. on dollar-basis. intereconomics, no. , world business trends quarter, a slight increase of production might be noticed, which will counter a bigger re- duction of the extensive invest- ment plans. hence the business enterprises' investment in fixed assets - in spite of the restrain- ing influence of the restrictive monetary policy - may be as- sumed to be the decisive factor in supporting production and employment. since government expenditures, in view of the forthcoming congressional elec- tions, will probably keep their expansive course, a stimulating impact on demand and produc- tion can be expected, provided that there are no more reces- sive influences originating from private consumption. in this field the negative effects of the declining employment on in- comes might be opposed to the strengthened increase of wages. for the real outcome it will be of decisive importance whether the tendency of prices to rise will slacken and thus favour the development of consumers' pur- chasing power. even such a relatively favourable economic trend will still be connected with rising unemployment. on a yearly average, gnp in real terms will only slightly increase. raw material markets new tendency on raw material markets in may significant price decreases on world raw material markets could be noticed parti- ally. in london, the fall of the quotation for non-ferrous metals was to p.c.; and in new york sugar and cocoa became considerably cheaper, too. alto- gether the price level on world markets for foodstuffs and indus- trial raw materials decreased by p.c. from the beginning to the end of may according to the hwwa-index on dollar basis. (compiled by the hamburg in- stitute for international econom- ics). the large-scale price reduc- tions were concentrated on goods being greatly affected by spec- ulation. reiterating purchasing waves created "unrestrained" price increases on these markets during the last months. without doubt the flight into these raw materials was caused by the fear of an increasingly inflationary development and by uneasiness in the foreign exchange markets. the prospect of a cyclically con- siderably diminished increase of raw material consumption and a stronger expansion of raw material production has ob- viously been nearly ignored. on the other hand, an opposite development was, for example, that of the prices for cotton, wool and rubber, which declin- ed nearly continuously since the turn of the year / . on these markets the connexion between the development of basic consumption and produc- tion relations and the market behaviour has obviously been maintained. the question is now, whether on markets affected by specula- tion a change in tendency hap- pened, too. during the last months repeated price reduc- tions could be noticed already. but they were only short-term and technical reactions to the preceding very strong price-in- creases. in order to take profits the speculators offered raw materials on a larger scale. fol- lowing the selling pressure the bulls bought very much and fast, effecting new price rises. this time, however, a changing ten- dency of speculative dispositions did not happen for several weeks already. this produces the impression that in general the boom on raw material mar- kets has meanwhile passed its highest level. compiled by the department on business cycles and statistics of the hamburg institute for in- ternational economics. publisher: hwwa-institut for wlrtschaflsforschung-ham- burg (professor dr heinz-dietrich ortlieb, dr dietrich keb- schull) and stiftung deutsches obersee..institut (professor dr gonther jantzen) editorial board: chief editor: dr otto g. mayer assistant cldef editors: hubert hoping, klaus kwasniewski editors: claus hamann, albrecht iwersen, helga lange, sabine schwarz, klauspeter zanzig address: neuer jungfernstleg zi, hamburg , phone: ( ) / copyright by verlag production and distribution: verlag waltarchlv gmbh, hamburg advertisements: representative dr hans klomen adveruslng prlca list: no. of january , rates of subscription: single issue: dm . ; annual rate: dm ,- (students: dm .-) publication dates: monthly printing: otto schwltzke, hamburg address: neuer jungfernstleg , hamburg , phone: ( ) oo weltarcitiv gmbh intereconomics, no. , page | a review on g-c n based photo-catalyst for clean environment manas ranjan pradhan , snehashis panda , binita nanda , * department of chemistry, institute of technical education and research, siksha ‘o’ anusandhan (deemed to be university), bhubaneswar, odisha, india *corresponding author e-mail address: binitananda@soa.ac.in | scopus id abstract in recent years, our mother earth is facing drastic environmental and energy crisis. to resolve this crisis, the search for suitable strategy becomes a challenge to the sciencetific community. in this aspect, graphitic carbon nitride (g-c n ) attracts the attention because of its super hardness, low density, chemical, thermal stability and biocompatibility. among various analogues, g-c n is considered as one of the most stable allotrope in the research hotspot drawn attention as metal-free and visible light responsive photocatalyst. moreover, g- c n acts as an n-type semiconductor and unique electrical, optical, structural and physiochemical properties. this makes g-c n and g- c n based materials, a new class of multifunctional nano platform. the polymeric structure of g-c n enables the tuning of surface of g-c n at a molecular level. however it has the lowest band structure among all the seven phases of cn. these properties enable the g- c n , an emerging and ideal candidate for clean energy production and environmental remediation. last but not least, this review article emphasizes on the summary and some invigorative perspective on the challenges and future directions towards the development of sustainability without environmental detriment. keywords: g-c n ; photocatalysis; hydrogen energy generation. . introduction in recent years, the global energy problem and environmental crisis are hindered the sustainability. this encouraged the scientists and researchers to develop some noble pathway for clean energy production as well as pollutants degradation strategies with the help of efficient photocatalytic materials [ ]. over the past decades semiconducting based visible light driven photocatalytic materials are the most suitable alternative that has attracted the attention of the researchers. conversion of water into hydrogen is the best technique and regarded as a promising route with a higher efficiency [ , ]. many photocatalytic systems have been explored for efficient absorption, utilization, and conversion of solar photons in a sustainable and greener mode [ , ]. a handful of semiconducting metals, metal oxides, and metal composites are extensively used as photocatalyst to harness solar energy (green technology) for cleaner environment. among all, the story of semiconductor photocatalysis starts with tio by fujishima and honda, and termed as ‘golden’ photocatalyst for a long period. the large band-gap of tio (anatase) is . ev restrict the broad spectrum of sun light. to handle these problem, scientist and researchers have taken the challenges and search a new semiconducting visible light responsive material which tackle the environmental remediation and solve the energy crisis. recently, a simple efficient, highly stable and sustainable polymeric material, graphitic carbon nitride (g-c n ),a n-type semiconductor, taken as a metal-free visible light responsive photocatalyst for h evolution and pollutant degradation. berzelius was the first man to synthesize it and after that liebig was named “melon” [ ]. but later on more simple and feasible method (thermal condensation) was implemented for synthesizing g-c n using nitrogen rich precursors like cyanamide, dicyandiamide, urea, thiourea and melamine as precursors [ ]. it is a stable allotrope of carbon nitride as there is a strong covalent bond between carbon and nitrogen [ ]. another way it is a poly-conjugated semiconductor which contains earth’s most abundant elements c and n atoms with a molar ratio c/n is . , suggesting g-c n is low cost material with two-dimensional stacking of π conjugated planes analogous to graphite. it is iso-structural with graphite where van der waals’ force holds the stacking layers (covalent c–n bonds) with each layer composed of tri-s-triazine units. it is bio- compatible, thermally and chemically stable in both acidic and alkaline environments. it has photo-electrochemical property in- oxidizability and waterproofing nature for which it is most wanted in photo-catalytic application and energy conservation [ - ]. wang et al. synthesized bulk g-c n for the first time in , using cyanamide were applied to photocatalytic h generation from water [ ]. after that, a number of review articles have been focused on the synthetic strategies of g-c n . basing on the heat and chemical resistance, g-c n exhibits unique stability. as prepared g-c n is non-volatile till the temperature reaches up to c, but completely decomposed at temperature c, confirm from thermogravimetry analysis (tga) [ - ]. in single layer of g-c n , mainly consist of triazine and tri-s-triazine, is considered as tectonic unit [ ]. different synthesis methods such as hydrothermal, physical vapour deposition, chemical vapour deposition, solid state methods, and thermal condensation are commonly adopted. among all, thermal condensation is the most commonly adopted technique, where basically nitrogen rich species are used as precursors. the most commonly used precursors are melamine, cyanamide, dicynamide, urea and thiourea etc [ ]. when melamine undergoes thermal reaction, self-condensation occurs along with deammonication process and produces intermediate products such as melam, melem, and melon respectively. which again thermal condensation at - c, g- c n is formed, which is shown in scheme- . despite the presence of many transition metal oxides like zno, tio which are active within uv region, corresponding to volume , issue , , - issn - open access journal received: . . / revised: . . / accepted: . . / published on-line: . . original review article biointerface research in applied chemistry www.biointerfaceresearch.com https://doi.org/ . /briac . https://www.scopus.com/authid/detail.uri?authorid= http://orcid.org/ - - - x http://orcid.org/ - - - x http://orcid.org/ - - - https://doi.org/ . /briac . manas ranjan pradhan, snehasis panda, binita nanda page | an optical wavelength nm, makes g-c n active under visible light. clearly, it is seen that the band gap of g-c n is . ev. scheme- . systematic approach synthesis of polymeric g-c n . due to thermodynamic losses and over potentials in the photocatalytic process the band gap lies between . - ev, which enhances the hydrogen energy generation with enough endothermic driving force and light absorption in the visible region. though g-c n has many applications towards clean energy and environment, but unfortunately its efficiency is low due to grain boundary effect, marginal absorption of visible light (< nm), very low surface area ( m g - ), low quantum efficiency, high recombination rate of electron-hole pair less active sites for interfacial photon reactions, slow surface reaction kinetics, and low charge mobility interrupt electron delocalization [ ]. its photo-catalytic activity thus be enhanced by modifying its electronic structure by doping [ ], templating [ ], co-catalyzing [ ], copolymerization [ ], heterogeneous catalysis [ ], and surface modification [ ]. amongstnumerous prospects, photocatalysis by establishing hetero-junction between twofold semiconductors, identified as z-scheme photo-catalysis [ – ]. it has been fascinatedbecause of consumption ofa greatpercentage of the solar spectrum and reduces the rate of recombination by driving the redox process at different sites of the catalyst. even photo-catalysis by doping is testified by zhang et al. that phosphorus atoms is introduced into the framework of g-c n by substituting c atoms [ - ]. as tri-s-triazine motif in g-c n is considered to be electron acceptor, then p atom becomes electron rich and tri-s-tri-azine will be electron-deficient which is favourable for the effective separation of photo-generated e – and h + pairs and improve the photo-catalytic efficiency [ - ]. in this book chapter, we are mainly focus on the green technology for a clean environment by pollution abetment and energy conservation. basing on green technology, photocatalysis is the safer, cleaner and greener method to reduce the environmental hazards and give an alternative path for hydrogen evolution to mitigate the energy crisis. taking this into consideration, finding a suitable catalyst is a challenging task. in this way, g-c n is a very good photocatalyst for hydrogen generation and pollutant degradation. this book chapter, also provide a comprehensive recent data generated by different authors regarding photocatalysis and energy evolution. . results photocatalysis: a promising route for energy and environment photocatalysis the goal of st century chemistry is to adopt energy efficient routes to avoid environmentally hazardous processes with replacement of harmful chemicals during production and uses. photocatalysis, a conventional green technology, the advanced oxidation process (aop) has the pivotal role in today’s clean environmental [ ]. as definition denotes, photocatalysis is a ‘green’ technique which accelerates the photoelectron in the presence of promoter. in the photocatalytic reaction, light is absorbed by an adsorbed substrate. therefore, in photo generated catalysis, semiconducting nano materials preferred as photocatalyst due to narrow band gap between the valance band and conduction band [ - ]. mechanism semiconducting materials having filled valence band (occupied by electrons) and an empty conduction band (unoccupied electronic states) are mostly sensitizes redox processes in presence of light. the two bands are separated by an energy gap particular to each semiconductor referred to as the band gap (eg). in the photocatalytic process, when a semiconducting material is subjected to radiation exceeding its band gap, establishing a redox environment. this helps in generation of e – and h + pairs in the valance band and conduction band [ - ]. these e – and h + pairs enable redox reaction and form different oxidative radicals on surface of semiconductor and enhance the photocatalysis process through three mechanistic ways such as: proper excitation, bulk diffusion and surface charge transfer [ ]. scheme . mechanism of photocatalysis reaction process. in a typical photocatalytic process, when the semiconductor photocatalyst is illuminated with light of sufficient energy (either uv/visible light source), the e – s of vb jumped to the cb, thus leaving an h + in vb is shown in scheme- . the holes (h + ) produced in vb, are trapped by the surface adsorbed water molecule and generates oh • radical. at the same time photo generated electrons (e – ) in cb react with the dissolved oxygen forming superoxide radical (o –• ), which again reacts with photon (h + ) to produce hydroperoxyl radical (ho • ) followed by the formation of h o . the charge transfer and production of highly oxidative radicals during the redox process enhances the photocatalytic ability of a semiconductor. the mechanism of photocatalysis is explained below and the schematic representation is shown in scheme- photocatalyst + hυ → e – (cb) + h + (vb) ( ) oh – + h + (vb) → oh • ( ) o + e – (cb) → o – • ( ) o – •+ h + → ho • ( ) ho • → h o + o ( ) h o + e – (cb) → oh • + oh – ( ) a review on g-c n based photo-catalyst for clean environment page | in this regard, the electronic structure of g-c n accountable the photocatalytic ability. the presence of two abundant element carbon and nitrogen in g-c n and the lone pair electron of nitrogen plays an important role in electronic structure. the combination of π bonding electronic states and the lone pair of nitrogen stabilizes the electronic lone pair state [ ]. the role of nitrogen content in optical properties of g-c n was again confirmed by abd el-kader et al. [ ]. to enhance the positive improvement in optical properties and photocatalytic performance, band gap is to be modified with negative ions in g-c n by doping [ ] as the position of vb and cb are responsible for oxidation and reduction levels. generally, the humo –lumo band gap of melem is . ev and it is reduced to . ev in case of melon and finally attain the band gap . ev with fully formation of condensed g-c n . the wave function investigated that the nitrogen pz orbitals and carbon pz orbitals drove vb and cb, where the photogenerated e – s and h + s are separated. this creates the oxidation and reduction cites in vb and cb respectively, which is responsible for splitting of water (h generation) and pollutant degradation independently in the nitrogen and carbon atom. wei et al. synthesized visible light responsive photocatalyst mesoporous tio /g-c n for phenol degradation. amorphous tio microsphere was coated with thin layer of g-c n was clearly visible from sem and tem study. from hrtem, it is clear that heterojunction formed due to the connection of the crystal lattice of tio and g-c n at the interface of tio /g-c n . the irregular mesoporosity of tio and the composites (tio /g- c n ) were confirmed from n adsorption and desorption study, which exhibited the type (iv) isotherm. uv-vis drs shows that the light absorption of tio was restricted to wavelength range at nm. but, after the decoration of g-c n on the surface of tio extended the absorption of light towards visible region. the pl spectra of tio was found to be in the range - nm due to band-band emission and surface oxygen vacancy effect. in the case of tio /g-c n composite the peak intensity was negligible which confirms the reduction of electron-hole recombination rate by the efficient separation of electron-hole pairs. during the photocatalytic degradation of phenol, there is a charge transfer through tio /g-c n heterojunction. the heterojunction was formed inside the anatase of tio structure, the growth of g-c n was restricted and only a thin layer of g-c n was embedded on the surface of tio . during the addition of precursor (cyanamide) and the intermediate product (melem and s-triazine) possibly react with tio and form tio -xnx after calcination (well confirmed through xps). in the heterojunction both g-c n and tio -xnx are irradiated under visible light, generates electron-hole pair. during this process, the transfer of electrons occurs from cb of g- c n to cb of tio -xnx, whereas the holes present in the vb of tio -xnx move towards vb of g-c n . the electrons accumulated in the cb of g-c n and tio -xnx react with atmospheric oxygen to produce superoxide radical (o -. ), which responsible for the degradation of phenol [ ]. sun et al. fabricated g-c n /zno photocatalyst with different zno content for decomposition of para nitrophenol and methyl orange. the thermal stability and weight of g-c n /zno deceases, when the temperature rises from - c. this shows that at temperature c, the composite is stable and above that combustion occurs and the weight of the g-c n decreases and at the same time zno increases. this again confirms from pxrd which reveals that the intensity of peak of zno in the composite increases with increasing calcination time. the bonding between zno and g-c n is probably due to condensation reaction between amino group of tri-s-triazine of g- c n and surface oh group of zno. from hrtem image it was revealed that there is an interface between g- c n and hexagonal wurtzite phase of zno. uv-vis spectroscopy discloses that the absorption shift to the lower region to nm corresponds to band gap of the composite is . ev. this arises due to the strong chemical bond between zno and g- c n and enhances the photocatalytic activity towards methyl orange and paranitro phenol. increasing zn content in the composite, remarkably enhances the photocatalytic activity. the photocatalytic activity of the composite is found to be increasing with increase in zno content as degradation of mo is about % for wt% of zno in g-c n in min. this shows that there is a strong synergism between zno and g-c n in g- c n /zno photocatalyst. the increased photocatalytic property of g-c n /zno is due to lower –ve conduction band potential of g- c n (- . ev) than that of zno ( . ev). photo induced e – s on conduction band of g-c n goes to that of zno through the interface and produces o .- from atmospheric oxygen. mo degradation charged the g-c n surface and again restore to the ground state. the two semiconductor also rebuild the electric field and creates the electron-hole separation, which accumulates a large number of electron on the surface of zno and enhances the photocatalytic activity towards mo degradation [ ]. he et al. fabricated z-scheme type moo /g-c n photocatalysts and evaluated for its photo degradation activities towards methyl orange (mo). from thermo gravimetric analysis shows that there is a weight loss in the composites as g-c n volatilized within temperaure range of - c. again vaporization of moo in the composites (moo /g-c n ) further loss the weight occurs within to c. the surface areas of moo /g-c n composites are more as compared pure moo and pure g-c n . the surface area of the composite (moo /g-c n ) increases due to the modification of moo grains on the surface of g-c n is and again decreases due to agglomeration of a higher amount of moo onto the surface of g-c n . uv-vis drs spectra delineates the optical properties of moo /g-c n fall in between those of moo and g-c n . this is because of both moo and g- c n possess nearly equal band gap. for this reason both the semiconductors exhibit nearly the same photo absorbance. moo shows less photocatalytic activity towards mo, after modification with g-c n the activity increases. as the % of moo increases the photocatalytic activity of mo increases ( . wt % is the highest) and again decreases because at high wt % of moo ( wt %) on g-c n may block the visible light absorbance and decreases the degradation percentage. furthermore moo /g-c n obeys the z-scheme mechanism as o – • and h + the two active species during photocatalytic degradation of mo [ ]. (ii) photocatalytic water spiltting: in recent year, production of clean energy is a big challenge. the conversion of solar energy to chemical energy is the most suitable greener method to mitigate the future energy crisis in cleaner way. this is because when hydrogen gas is burned as fuel, water vapour is released, which restricts global warming manas ranjan pradhan, snehasis panda, binita nanda page | and emission of other air pollutants. in this regard, photocatalytic water splitting, is the alternative way to conserve energy sources. because in this process relies on sunlight and semiconductor and considered as solar-to-hydrogen conversion (sth). this can be calculated as: sth = output energy as h / energy of incident solar light ( ) apparent quntum efficiency is the appropriate method to evaluate the photocalytic performance aqy=nr/i ( ) where, n is the number of electrons involved, r is the rate of production of h and i is the rate of incident radiation (photons). for photocatalytic hydrogen generation photochemical or photoelectrical cells are generally used but thermodynamically the process is difficult due to very high change in free energy of the process which is about + . kj/mole. for the generation of hydrogen basically three steps are used. first of all electron-hole pair is to be produced by absorption of light with energy equal or greater than band gap energy of photocatalyst. secondly, the electron-hole pairs called charge carriers to migrate to the surface of photocatalyst or combine in the core. last of all the photogenerated electron in cb reduces water to liberate hydrogen whereas the holes oxidise water molecules to liberate oxygen at vb [ ]. the mechanism of the reaction is given below and explained through schematic diagram . h o + hυ → h + o ( ) h + + e ‒ → h (reaction at cb) ( ) h o → h + → o (reaction at vb) ( ) qin eta al. developed a heterostructure photocatalyst by coupling cu p with g-c n which are p and n type semiconductors respectively for effective charge separation there by improving photocatalytic hydrogen generation. this heterocatalyst shows times more activity than bare g-c n with aqe of . % at nm. as cu p has low cost and is earth abundant with a band gap of . ev that can improve the charge separation and enhance photocatalytic performance of g-c n . hydrogen generation by g- c n is faint but adding cu p increases the rate of hydrogen production which is about . times higher than bulk g-c n . it is to be noted that cu p is not an active photocatalyst but mixture of cu p and g-c n increases slightly the generation of hydrogen but when a heterojunction is formed between cu p and g-c n the production of hydrogen increases many more times. it is evident from spv spectra. the spv signal identifies the light response of wavelength range and how efficiently the charged pairs are separated in the photocatalyst. the spectroscopic and electrochemical analysis says that the heterojunction possesses efficient charge separation capacity which facilitates photochemical activity. when cu p is loaded over g-c n an electron transfers from g-c n to cu p takes place until the fermi level becomes equal. when the heterojunction photocatalyst is exposed to visible light, the photogenerated electrons in cb of cu p diffuses into cb of g-c n through p-n junction. simultaneously the photogenerated holes in vb of g-c n diffuses into vb of cu p. now the electron in g-c n reduces h + ion liberating hydrogen and holes oxidizes water to liberate oxygen henceforth justifying water splitting capability [ ]. scheme . schematic representation of h gas generation. wang and his team have synthesized g-c n and mn doped g-c n nanoribbon for photocatalytic degradation of mb coupling with water splitting. the controlled synthesis of mn doped g-c n allows better results compared to bulk g-c n . hrtem confirms the nanoribbon morphology of mn doped g-c n with high surface area m /g as compared to bulk g-c n ( . m /g). the successful doping of mn onto the surface of g-c n was observed by xps and eds mapping. from the band gap of both g- c n and mn doped g-c n nanoribbon ( . and . ev respectively) confirms that both are visible light active. mn dped g-c n nanoribbon shows better h and o yield ( . and . µmol/gcat) respectively. again coupling of photocatalytic performance and water splitting shows better results in the case of mn doped g-c n nanoribbon. this is because construction of nanoribbon and doping of mn helps in separation of electron ad hole in the photocatalyst. mainly doping of mn facilitates the formation of oh • from h o intermediate product. the coupling reaction solves the problem of h o production and offers the possibility of energy utilization mode of waste water [ ]. different materials used in photocatalysis process are summarized in the table . table- . tabulations of different synthetic methods of g-c n based composites and their applications. s.l. no catalysts methods of synthesis application references na-doped g-c n solid state method photodegradation of α-ethynylestradiol cu (i) – g-c n wet impregnation-ultrasonication method photodegradation of atrazine g-c n – wo hydrothermal method h energy production se – doped g-c n ultrasonication method h - production g-c n /silica gels solvothermal method white light emitting devices g-c n pyrolysis process photo electrochemical sensing of methylene blue mno /ag/g-c n hydrothermal method photoreduction of co g-c n /bi wo hydrothermal method co photoreduction g-c n -ti c tx calcination process h evolution cuo/g-c n sonication process -nitrophenol degradation and o evolution g-c n -tio stirring followed by calcination methylene blue degradation nio/g-c n hydrothermal photocatalytic water splitting wo -g-c n hydrothermal sulfamethoxazole degradation a review on g-c n based photo-catalyst for clean environment page | s.l. no catalysts methods of synthesis application references mos -qds/g-c n wetness impregnation method h evolution tio -g-c n hydrothermal method organic pollutant degradation wo -g-c n calcination process degradation of methylene blue and -chlorophenol n-tio -g-c n impregnation method h evolution g-c n -biobr ultrasonic method pollutant degradation c-sic/g-c n pyrolysis method degradation of methyl orange pani-g-c n oxidative polymerization process methylene blue degradation . conclusions in summary, this review article mainly highlights green technology for clean environment. in this regard, g-c n based composites are proven to be a good photocatalyst for environmental remediation and energy recovery. to this end, the enhancement of photocatalytic performance of g-c n is mainly due to three factors such as: ) visible light responsive, ii) low rate of recombination of photoinduced charge carriers, and iii) high surface area. these above properties enable to anchor different foreign materials on the surface of g-c n nanosheet and further activate the performance. this review summarizes a 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/biobr composites visible light driven photocatalysis sterilization and reaction mechanism. new journal of chemistry , , , http://dx.doi.org/ . /c nj a. . gan, z.; zhou, w.; ding, z. a metal free c-sic/g-c n composite with enhanced visible light photocatalytic activity. rsc advances , , - , https://doi.org/ . /c ra g. . han, c.; liu, j. insitu synthesis and enhanced visible light photocatalytic activities of novel pani-g-c n composite photocatalysts. journal of mataerials chemistry , , - , https://doi.org/ . /c jm e. . acknowledgements authors are thankful to the management soa (deemed to be university) for constant encouragement. © by the authors. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). https://doi.org/ . /s - - - https://doi.org/ . /c ta g https://doi.org/ . /c ta d https://doi.org/ . /c dt g https://doi.org/ . /c ra b https://doi.org/ . /c qi d https://doi.org/ . /c cy f https://doi.org/ . /c ra d https://doi.org/ . /c dt a https://doi.org/ . /c dt f https://doi.org/ . /c ta f http://dx.doi.org/ . /c nj a https://doi.org/ . /c ra g https://doi.org/ . /c jm e reviews and empirical), almost assumes the character of a fetish and mitigates against efforts at a "positive critique" of ideology. such a critique can only be based on what marx called "positive knowledge," and this not about the "superstructure" but about the "infrastructure." from the standpoint of the science of society, ludz's approach begs the political and institutional questions of the totality of marx's approach to history. but from the standpoint of the sociology of knowledge, his "starting points to an im- manent critique" of the concept of ideology and marxist theory are a major con- tribution. g. l. u l m e n new york t h e s t r u c t u r e o f e c o n o m i c s y s t e m s . by john michael montias. new haven and london: yale university press, . xii, pp. comparers of economic systems—and which of us is not?—will benefit from this pioneering treatise. its impact on fellow specialists should be immediate. later on, as its insights shape the efforts of economists, political scientists, and historians to evalu- ate economic systems, all will gain. the author's heroic objective is to define and apply criteria and measures of system performance that will be independent of the systems themselves. to this end he draws on information theory and the theory of organiza- tions in order to augment the narrow framework of contemporary economic theory. his results are exploratory rather than definitive. this is the work of a thoughtful and conscientious scholar surveying the tasks involved, proposing analytic approaches, and recognizing inherent difficulties. it is a challenge to further work. the two chapters of part define some basic concepts and lay out an analytic framework. part contains three chapters: "system structure and normed outcomes," "common desiderata and efficiency," and "from theory to measurement." here mon- tias presents methodological suggestions and cautious observations on the work of others relating to the macroeconomics of the comparison of systems. part deals with microcomparisons involving the elements of system description. its five chapters dis- cuss more detailed aspects of economic operations: consumption and distribution, technologies utilized, forms of interactions among participants, ownership and custody, and competitive processes. the four chapters in part on organizations, hierarchies, and associations take up issues of incentives, power, autonomy, and decentralization. the three chapters of part discuss the goals of producing enterprises and their con- sequences for an economic system. a concluding chapter reflects on fruitful directions for further research. the author is as broad as his subject. while much of his analysis focuses on the ussr, there is considerable attention to eastern and western europe and some refer- ence to japan and china. in previous research montias has given as painstaking anal- yses of the polish and rumanian economies as well as stimulating appreciations of the forces at work in eastern europe. his interests range from the fine arts and linguistics to mathematics and economic theory. this breadth of mind and range of coverage is both essential for the task in hand and a frustrater of neat conclusions. montias draws on a wide range of materials. his well-selected references will assist anyone pursuing the issues he discusses. relevant recent additions to his list might include the work of david granick on eastern european management, quanti- tative economic policy and planning by nicolas spulber and ira horowitz (norton, ), and vaclav holesovsky's economic systems: analysis and comparisons (mc- graw-hill, ). on the economics of bureaucracies, some readers will find the work of william niskanen and others useful. technicians should weigh the applicability of fuzzy set theory (see for example, c. v. negoita and m. sularia, "on fuzzv mathe- slavic review matical programming and tolerances in planning," economic computation and economic cybernetics studies and research [bucharest], , no. , pp. - ). this treatise offers an abstract framework to contain the diverse realities of the economic systems around us. the challenge now is to fill the intervening space, work- ing up from empirical detail and down from strict theory, to build a tested body of understanding. contributions to the effort may well appear in the new journal of com- parative economics whose editor, not surprisingly, is john michael montias. holland h u n t e r haverford college t r e n d s in t h e s o v i e t o i l a n d gas i n d u s t r y . by robert w. camp- bell. a resources for the future book. baltimore and london: the johns hop- kins university press, . xvi, pp. tables. figures. $ . . this compact, succinct little book is a useful companion to the author's economics of soviet oil and gas ( ). it admirably fulfills the stated intentions of updating the data base of the earlier work and reviewing the most important developments since . separate chapters deal with soviet energy policy, exploration, drilling, oil pro- duction, oil transport, oil refining, the gas industry, the economic reform in oil and gas, and soviet participation in world energy markets (as buyer and seller). in cogent summaries that bracket the more detailed discussion, professor campbell argues that soviet oil and gas planners now face problems different from those of the s and s, and that their success in dealing with these problems will determine both the level and structure of future soviet energy development. as usual, careful scholarship routs glib generalizations—for example, the undue pessimism about a soviet "energy crisis," and the undue optimism that the u s s r can bail the west out of its own energy crisis with massive energy exports. professor campbell attributes many of the problems soviet energy planners face to difficulties in meeting technological challenges—in drilling, oil refining, pipeline construction and operation, and the production of both oil and gas. this line of argu- ment is backed up by a wealth of technical detail. insightful (if tantalizingly brief) discussions deal with refinery mixes and product quality, the utilization of natural gas, the export of crude oil versus refined products, and planning methods (especially the attempts to apply optimizing models). in view of the apparent space constraints, soviet oil purchases in the middle east receive overmuch attention, with perhaps the least satisfying results. (arms sales and comecon debt instruments are stressed, to the relative neglect of the desire to minimize transport costs, given fixed commitments to communist allies—to the reviewer, the best explanation of those purchases.) unfortu- nate publication delays have left the data series two or three years out of date, in a situation subject to rapid change. not to carp, however—this is a valuable book for serious students of soviet energy policy and more general readers alike. a r t h u r w. w r i g h t purdue university t h e c l i m a t e s o f t h e s o v i e t u n i o n . by paul e. lydolph. world survey of climatology, vol. . amsterdam and new york: elsevier scientific publishing company, . xii, pp. illus. dfl. . $ . . dr. lydolph has performed a valuable and long overdue service in compiling a com- prehensive reference on climatic factors in the soviet union. his stated intent "is to present general climatic information that can be used as a basis for other studies which - / - - - /$ . © geol. soc. india journal geological society of india vol. , june , pp. - gas-hydrates in krishna-godavari and mahanadi basins: new data kalachand sain , maheswar ojha , nittala satyavani , g.a. ramadass , t. ramprasad , s. k. das and harsh gupta csir - national geophysical research institute, uppal road, hyderabad - national institute of ocean technology, velachery-tambaram main road, chennai - csir-national institute of oceanography, dona paula, goa - ministry of earth sciences, prithvi bhavan, lodhi road, new delhi - email: kalachandsain@yahoo.com than times of india’s present natural gas reserve, and it is envisaged that % recovery from this huge cache of energy can meet india’s overwhelming energy requirement for about a century. therefore, the identification and quantitative assessment of gas-hydrates along the indian margin has been very essential. moes program under the aegis of the ministry of earth sciences (moes), goi, a comprehensive research-oriented gas- hydrates program has been launched emphasizing the scientific and technology development for identifying promising sites on regional scale and estimating the resource potential, studying the impact of dissociation of gas-hydrates on environment, and developing environment-safe technology for production. the national geophysical research institute (ngri) and national institute of oceanography (nio) are pursuing the scientific objectives for the identification, delineation and evaluation of gas- hydrates in various offshore basins. while the national institute of ocean technology (niot) is developing remotely-operated vehicles and autonomous coring systems for validating the ground truth, and viable technologies for producing gas from gas-hydrates. the national gas hydrate program (nghp), under the auspices of the ministry of petroleum & natural gas (mop&ng), goi, has also been formulated in which the oil & natural gas corporation limited, oil india limited, gas authority of india limited, directorate general of hydrocarbons, ngri, nio, niot, indian institute of technology at kharagpur and kanpur, and indian school of mines are carrying out research for geo-scientific investigation of gas-hydrates along the indian shelf followed by technology development for production of gas from gas-hydrates. background gas-hydrates are crystalline substances consisting of mainly methane and water, and occur in shallow sediments of outer continental margins and permafrost regions. they are formed at high pressure and low temperature regime when supply of methane gas exceeds the solubility limit. unlike natural gas, oil and minerals, gas-hydrates are not stable at standard temperature and pressure (stp). one volume of gas-hydrates, when dissociated, releases volumes of methane at stp. since methane is the lowest molecular weight hydrocarbon, use of gas-hydrates as fuel will cause less pollution to the environment. these have attracted the global attention due to their natural occurrences in abundance and huge energy potential. the methane locked as gas-hydrates is envisaged as - x m (boswell and collett, ). only % recovery from this gigantic reserve may be sufficient to meet the global energy requirement for about years (makogon et al. ). thus, gas-hydrates seem to be a viable major energy resource of future, and have been identified globally either by geophysical, geochemical and geological surveys or by drilling and coring (boswell and saeki, ; ruppel, ; sain and gupta, ). besides having the energy potential, the study of gas-hydrates is also important from natural hazards point of view related to seafloor subsidence, slumps and slides (gupta and sain, ). the bathymetry, seafloor temperature, total organic carbon (toc) content, sedimentary thickness, rate of sedimentation, geothermal gradient indicate good prospects of gas-hydrates along the indian margin (sain and gupta, ). a total volume of ~ trillion cubic meter of methane gas, stored in the form of gas-hydrates, has been prognosticated (collett et al. ) within the indian exclusive economic zone (eez). this volume of gas is more jour.geol.soc.india, vol. , june kalachand sain and others gas-hydrates are mainly recognized by seismic experiment with the identification of an anomalous seismic reflector, known as the bottom simulating reflector or bsr, based on its characteristic features (sain and gupta, ). the bsr is a physical boundary between sediments containing gas-hydrates above and free gas-saturated sediments below, and is often associated with the base of gas-hydrate stability field. hence, theoretical map of gas- hydrate stability zone plays an important role in identifying bsrs on seismic sections. by analyzing available multi- channel seismic (mcs) data, the bsrs were identified earlier in the mahanadi (mn) and andaman (am) regions (sain and gupta, ). the first scientific expedition using a remotely operated vehicle, recently developed by niot, brings out chemosynthetic habitats at a depth of m and implies the surface expression of gas-hydrates in kg basin (ramadass et al. ). the drilling and coring by nghp expedition- (collett et al. ) have validated the ground truth where gas-hydrates were predicted from surface seismic data in the bay of bengal. this has boosted to advance further research for the detection, delineation, and quantification of gas-hydrates along the indian margin followed by a strong initiative for production in an environmental-safe manner. recent data major portions of the deep-water regions along the indian shelf are not fully explored. most of the mcs data examined so far were acquired for the exploration of conventional hydrocarbons and may not be adequate for evaluating the resource potential and understanding the genesis of gas-hydrates. under the sponsorship of the moes, very recently, ngri has acquired lkm of -d mcs data, using a modern ship equipped with the state-of- the-art acquisition system, between to m water depth in the kg and mn basins (fig. ) with a view to identifying new prospective zones, and evaluating the resource potential. the data are of high quality that has produced very good image of shallow sediments in both basins. figure shows seismic sections along representative lines (shown by red and green in fig. ). preliminary findings the preliminary analysis of recently acquired seismic data delineates widespread occurrences of distinct bsrs over a large area (shown by white lines in fig. ) in both kg and mn basins. figure exhibits distinct bsrs identified along representative seismic lines in these two basins. the gas-hydrates stability thickness map (sain et al. ) that has been computed theoretically using the available bathymetry, seafloor temperature and geothermal gradient data has helped in identifying the bsrs from seismic sections. as the energy potential of gas-hydrates is tremendous, the recent investigation provides great hopes to overcome the present energy crisis of india. future work by employing a suite of approaches for the qualification and quantification of gas-hydrates (sain and gupta, and references therein) to the new data, we will be able to provide information with regard to (i) understanding the petroleum system associated with gas-hydrates; (ii) delineating the extension of sediments containing gas- fig. . locations of seismic profiles (black lines) along which mcs data have been acquired recently in (a) mn and (b) kg basins along the eastern indian margin. the identified bsrs have been marked by white. red and green lines show the locations of seismic sections that exhibit representative bsrs in fig. . jour.geol.soc.india, vol. , june gas-hydrates in krishna-godavari and mahanadi basins: new data hydrates; and (iii) quantifying the amount of gas-hydrates in these two basins. the information derived from geological, geochemical, and biological data collected by nio will be assimilated, and the ground truth will be validated by niot. acknowledgements: we thank the director, csir-ngri for his permission to publish this work. the ministry of earth sciences, goi is gratefully acknowledged for financial support and encouraging gas-hydrates research at csir- ngri. fig. . . distinct bsr on specimen seismic sections along the (a) red and (b) green lines, shown in fig. in mn basin. the cdp interval is . m. fig. . . distinct bsr on specimen seismic sections along the (a) red and (b) green lines, shown in fig. in kg basin. the cdp interval is . m. references boswell, r. and saeki, t. ( ) motivations for the geophysical investigation of gas hydrates. in: m. riedel, e. willoughby, and s. chopra (eds.), geophysical characterization of gas hydrates. society of exploration geophysicists geophysical developments series , pp. - . boswell, r. and collett, t.s. ( ) current perspectives on gas hydrate resources. energy environmental science, v. , pp. - collett, t.s., riedel, m., cochran, j., boswell, r., presley, j., kumar, p., sathe, a.v., sethi, a.k., lall, m., sibal, v.k., nghp expedition scientists, and nghp expedition ( ), initial reports, directorate general of hydrocarbons, noida and ministry of petroleum & natural gas, india. volumes. gupta, h.k. and sain, k. ( ) gas-hydrates: natural hazard. in: p. bobrowsky (ed.), encyclopedia of natural hazards. springer, in press. makogon, y.f., holditch, s.a. and makogon, t.y. ( ) natural gas hydrates - a potential energy source for the st century. jour. petrol. sci. engg., v. , pp. – . ramadass, g.a., ramesh, s., selvakumar, j.m., ramesh, r., subramanian, a.n., sathianarayanan, d., harikrishnan, g., muthukumaran, d., jayakumar, v.k., chandrasekaran, e., murugesh, m., elangovan, s., prakash, v.d., radhakrishnan m. and vadivelan, m. ( ) deep-ocean exploration using remotely operated vehicle at gas hydrate site in krishna– godavari basin, bay of bengal. curr. sci., v. , pp. - . jour.geol.soc.india, vol. , june kalachand sain and others ruppel, r. ( ) methane hydrates and the future of natural gas. mitei natural gas report, supplementary paper on methane hydrates . p. . sain, k. and gupta, h.k. ( ) gas hydrates: indian scenario. jour. geol. soc. india, v. , pp. - . sain, k. and gupta, h.k. ( ) gas hydrates in india: potential and development. gondwana res., in press, doi: . / j.gr. . . . sain, k., rajesh, v., satyavani, n., subbarao, k.v. and subrahmanyam, c. ( ) gas hydrates stability thickness map along the indian continental margin. marine petrol. geol., v. , pp. - . 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f e f f f e> /suo <feff b e e e e e b c b e c f f d f b d e a c a f b f b a f a e c f e e e e d e a c f d e e c f d f b d e f e f c c a f e a c c a d d c c e> /sve <feff e e e e e e c c e e e f d c c b f d f b d e f d f c c f c c e e f b e f b d e e b d f b d e b e f e f f f e f e e> /enu (use these settings to create adobe pdf documents suitable for reliable viewing and printing of business documents. created pdf documents can be opened with acrobat and adobe reader . and later.) >> >> setdistillerparams << /hwresolution [ ] /pagesize [ . . ] >> setpagedevice microbial fuel cell with a nano-membrane and two expired medicinal drug-feeding cathode: a novel strategy vol.:( ) international journal of energy and environmental engineering ( ) : – https://doi.org/ . /s - - -z o r i g i n a l r e s e a r c h microbial fuel cell with a nano‑membrane and two expired medicinal drug‑feeding cathode: a novel strategy sasan nasirahmadi  · behrouz akbari‑adergani received: december / accepted: january / published online: february © the author(s) . this article is an open access publication abstract in recent years, there has been developing interests in microbial fuel cell (mfc) technology as a hopeful approach to overcome worldwide energy crisis that will come into account by restricting fossil fuels consumption in the future. in addition, many drugs around the world are accessible to some populations easily and remain unused annually. this paper discusses bioelectricity generation with whey degradation in a dual chambered mfc in the presence of some expired medicinal drug-feeding cathodes. consequently, a two-chamber mfc applied using escherichia coli as biocatalyst, humic acid as electron mediator and nafion with a nm in size as nano-membrane. the results showed that the open-circuit potential was .  v at ambient condition. stability of the voltage was exceeded  h. acetaminophen codeine and bismuth—as two expired medicinal drugs—applied as possible catholyte. in conclusion, bismuth revealed more opportunity for power deriving in comparison with acetaminophen. the best values were close to .  ×  −  w and .  ×  −  a, referring to power generation and current production, respectively. keywords acetaminophen codeine · bismuth · mediator · microbial fuel cell · whey abbreviations a ampere bod biological oxygen demand ce columbic efficiency cm centimeter cod chemical oxygen demand dns dinitrosalicylic acid g gram h hour l liter m molarity mfc microbial fuel cell mg milligram min minute ml milliliter n normality ocv open-circuit voltage pc personal computer pem proton exchange membrane sd standard deviation sem scanning electron microscope w watt introduction by confronting environmental pollution issues and fossil fuels overconsumption, it is manifest for humanity to explore a utile, trusty, and clean energy system to replace the current energy production systems. a great volume of expired and outdated drugs as well as generated wastewater determined by chemical and biological oxygen demand (cod and bod) concentrations [ – ] are other important issue imposing lots of expense on governments around the world. in addi- tion, whey is a well-known product of cheese processing industry [ , ] and could be used as suggested biochemical analyte for generation of bio-derived source electricity. the possibility of using mfc for power generation has studied before [ – ]. some researchers studied the principles of mfc especially in selecting microorganisms of interest [ ], economical substrate [ ], pilot-plant study for power pro- duction [ ], modeling of biofilm constitution with engi- neering aspect [ ], and role of electron acceptors in mfcs [ ], respectively. the other groups verified the importance of this technology for power production [ – ]. several * behrouz akbari-adergani analystchemist@yahoo.com nanotechnology products laboratory, food and drug laboratory research center, food and drug organization, ministry of health and medical education, p.o. box  - , tehran, iran http://crossmark.crossref.org/dialog/?doi= . /s - - -z&domain=pdf international journal of energy and environmental engineering ( ) : – kinds of mediators had applied in such system to augment the electron transfer rate, but they are generally expensive to be used in pilot or industrial scale program of mfc manu- facture and showed toxicity to secreted biocatalysts for long- period operation [ ]. in addition, several microbial systems with various substrates and mediators have been reported [ – ]. to the best of our knowledge, this is the first sur- vey presenting mfcs for generating electricity using expired drugs as electron shuttle. the main novelty was investigation and introduction of electricity harvesting from whey waste- water in the anode compartment, especially applying two expired medical drugs in cathode compartment of mfc as a new suggested trend and their functions as a light at the end of the tunnel in terms of power generation by mfc. materials and methods chemicals and materials all chemicals used as our previous work as follows [ ], unless otherwise stated. gela dairy product industry (amol, iran) was the provider of substrate. excess proteins in sub- strate were precipitated by acid solution (hcl,  n). the autoclaving of solution was carried out at psig,  °c for  min. after passing of cooling down process to mild temperature, it underwent centrifuging at ×g-values of rcf in units of times gravity for unwanted solids removal. then, the supernatant transferred to refrigerator for  h and stored. rohani hospital (babol, iran) was the provider of microbial catalyst (escherichia coli) as a close coopera- tion. microorganisms have grown in an anaerobic condition. the anode mediator and cathodic electron shuttles was sup- plied by merck (darmstadt, germany). figure  depicts the schematic diagram of the mfc and its auxiliary equipment [ , ], made of plexy glass material. the total volume of fig. schematic diagram of a typical two-chamber mfc applied for bioelectricity generation international journal of energy and environmental engineering ( ) : – cells was  ml, which  ml out of expressed primary volume was used as working volume. graphite was the selected electrode which has been provided in the size of  mm ×   mm ×   mm. the proton exchange membrane (pem, nafion  with a nm pore size, sigma-aldrich) provided to separate two chambers of mfc. ordinarily, all materials used in the experiments were analytical grade and supplied by merck (dortmund, germany) except acetami- nophen codeine (  mg) and bismuth (  mg) bought from local pharmacy. in all solutions, digital metrohm ph meter (model ) equipped with a combined glass–calo- mel electrode was used to adjust the ph. dinitrosalicylic acid method applied to measure whey consumption using colorimetric method [ ]. the microorganism growth monitoring was accomplished by spectrophotometer (unico, usa) established as optical density. sem (philips xl scanning microscope, philips, the netherlands) employed to determine the shape and surface morphology of electrode in the present mfc. the graphite was coated with gold before the sem measurement with the selected magnification of . arrangement of medium and inoculum the medium is comprised of glucose, yeast extract, ammo- nium chloride, and peptone in grouping of , . , . , and .  g/l, respectively. it was disinfected by autoclaving at  °c, psig for  min. initially, the ph of medium, inoculum, and other parameters had adjusted in . . there- after, it was heated at  °c. the e. coli had completely developed for  h in  ml flux with no additional shak- ing. the sampling was done in every .  h to investigate the substrate utilization on reduced sugar content by aforemen- tioned technique [ ]. anodes and nano‑membrane pretreatment to keep up layer for good conductivity, the two compart- ments preserved in double-distilled water when the bioreac- tor was not being applied [ ]. the anode compartment had introduced to serial pretreatment, which has been engrossing % ethanol for  min and in .  m hcl for .  h. after every usage, cathodes were immersed in .  m hcl, .  m naoh, for .  h, independently to clear any metallic and normal contamination by exposing indistilled water before use, respectively [ ]. nafion membrane was exposed to serial treatment to remove contaminations which include washing the film for .  h, immersion in . % h o , fol- lowing washing with double-distilled water, re-immersing in acidic solution and eventually re-exposing to distilled water, respectively. depiction of the data procurement framework simple computerized information procurement had pro- duced to record sampling information in every   s. the framework records measurements for variable resistances which were imposed to the mfc. by dividing the obtained voltage from characterized resistance, the output current recorded. then, the system provides power calculation by multiplication of voltage and current. in addition, the microcontroller sends the essential information to a pc by analogue–digital converter. moreover, unique capacity of matlab programming ( . , a) was utilized to store and synchronically show the received information. statistical analysis all facts are presented in this text as mean result  ±  sd (standard deviation). statistical analysis were assessed applying the t test and considered significant at p <  . level. all figures shown in this article have been received from three unbiased experiments with similar results. results and discussion mfc performance power deriving was accomplished applying the by-product, abundant, and easily available source of food industry. the effect of mediators as electron promoters had investigated. polarization is the difference of electrical potential between two ends of an electrical tool when there is no external load connected. hence, there is not external electric current flow between the ends. it is sometimes given the symbol voc or ocv; but in network analysis, this voltage is also known as the thévenin voltage. as resistance had reduced in such gadget, the voltage will lower. in the first moment of action, the voltage was in lower level (  mv) and then gradually reached to a high value. to put in a nutshell, carbon source utilization and final product formation in the form of bioen- ergy were the outcome of this stage [ ]. open-circuit voltage is measured in the presence of humic acid in anode cham- ber with no catholyte involvement during about .  days. following  h of operation, the recorded voc value was .  v. it was thoroughly unchanged for more than  day as our previous applied protocol [ ]. finally, a decrease as instability was observed (fig.  ). it can be attributed to decrease of lactose content in the anode chamber by bacteria depleting as substrate after  h. generally talking, polariza- tion curve is a main concept in electrochemical reactions. in other words, it is a law based on kinetic principals that is visualized as a plot of current density versus electrode poten- tial or having three parameters as voltage, current, and power international journal of energy and environmental engineering ( ) : – in a plot simultaneously. the achieved data rely on electrical parameters involved in the mfc. in figs.  and , the polari- zation curve in the presence of acetaminophen codeine and bismuth as suitable catholyte is shown. the selected media- tor in mfc was humic acid ( .  mol/m ) based on our previ- ous work due to highlighted potential [ ]. derived power and related current were close to .  ×  −  w and .  ×  −  a, respectively. the mediator in mfc was the main factor in increas- ing electron transfer interestingly achieves more power production and cell current efficiency. the drawbacks of mfc were mentioned in the previous scientific papers [ ]. one of the expressed suggestions for overcoming proposed issue is identification of new mediators. figures  , show power generation in the presence of two aforementioned expired medicinal drugs as hygienic organization wastes. the maximum power and current production in the pres- ence of acetaminophen and bismuth as novel cathodic mediators was .  ×  −  w, .  ×  −  a, .  ×  −  w and .  ×  −  a, respectively. the maximum value of voc is attributed to the presence of expired drugs as electron mediators. humic acid acts as electron acceptor in the anode compartment and two expired medicines act as electron shut- tle in the cathode chamber. these outputs are comparable to other researchers’ findings [ , ], especially in a case without using nanomaterial except the selected membrane. in this work, a novel approach to bioelectricity generation and new limited medicinal waste management opportunity as a novelty was introduced and developed. to best of our knowledge, this is the first attitude as a light at the end of the tunnel upon applying and developing expired drugs as mediator in cathode compartment of a bioreactor like as mfc. although the obtained quantities based on power and generation are not in high level, but the results open a new horizon for related industries and compartments to investi- gate more in such a new introduced concept. fig. initial open-circuit voltage (ocv) versus time following current switch-off of fabricated mfc [ ] vo lt ag e (m v) time (hour) fig. polarization curve in the presence of acetaminophen codeine international journal of energy and environmental engineering ( ) : – characterization of graphite electrode as our previous work, the same electrodes were applied for power generation and transformation in designed elec- trical circuit. figure  a, b shows surface of the electrode before and after the operation. in addition, sem image of the surface electrode with fixed regulated magnification of successfully shows characteristic of the graphite plate (fig.  ). sem imaging on the applied graphite electrode in the size of  cm ×   cm was established to character- ize the shape and surface morphology. philips xl scan- ning microscope, (philips, the netherlands) was the fea- tures of applied sem. coating of membrane was achieved with gold before taking any action. the surface impurities have depicted on the electrode surface with black arrows embedded in fig.  . based on obtained sem, electrodes need retreating to achieve a better efficiency if designed to be reused. cod and bod removal efficiencies to assess the stable performance of the mfc (fig.  ), cod removal efficiency and voltage output were considered as indicators. the mfc were operated continuously for  h. approximately, after  h, a stable condition was achieved for the mfc. maximum cod and bod removal up to and % was obtained for the selected wastewater with average initial concentration of , and ,  mg/l, fig. polarization curve in the presence of bismuth fig. graphite electrode connected with wire before (a) and after (b) bioelectricity generation [ ] fig. sem image of graphite electrode, magnification of international journal of energy and environmental engineering ( ) : – respectively. the efficiency of cod removal was in a very good agreement with the maximum reported efficiency and %, respectively [ – ]. columbic efficiency columbic efficiency (ce) was calculated according to logan and his co-workers [ ]. the result is shown in fig.  . for whey wastewater, the ces increased over time. after  h, the ces reached its maximum value, indicating that microorganisms consumed whey as close to %. in addition, the electrons in the removed substrate were used for current production. the percentage of columbic effi- ciency reveals a good phenomenon based on data obtained from fig.  [ ]. fig. cod and bod removal efficiency in  day operation of mfc bo d /c o d re m ov al (% ) time (hour) bod removal codremoval fig. columbic efficiency of the fabricated mfc ce (% ) time (hour) international journal of energy and environmental engineering ( ) : – conclusion whey utilized as selected analyte in the mfc. the per- formance of mfc investigated using two expired medici- nal drugs so-called acetaminophen codeine and bismuth implementing as mediatory agents in cathode compartment. the result of this study indicated that humic acid served as suitable mediator. implemented acetaminophen as expired drug was unsuitable choice as cathodic electron acceptor, but bismuth opened a new horizon toward working on other expired therapeutic drugs in cathode compartment for ideal performance. the most interesting finding was that the pro- duced power in the presence of acetaminophen codeine was lower than ocv in the absence of catholyte. the reason for this is not clear, but it may have something to do with relative competent groups for electricity exists in aceta- minophen codeine. the maximum power and current was .  ×  −  w and .  ×  −  a, respectively, although further studies will be need on many aspects of this tech- nology before these approaches could be commercialized successfully, but these results provided a new horizon to produce bioelectricity in a world where the energy crisis threatens its inhabitants. the future program will be focused on using different class of antibiotics and nano-materials to develop new introduced horizon. acknowledgements the food and drug control reference laboratories and the water safety research center due to their laboratory facilities support in this work are acknowledged. compliance with ethical standards conflict of interest the authors have declared no conflict of interest. open access this article is distributed under the terms of the crea- tive commons attribution . international license (http://creat iveco mmons .org/licen ses/by/ . /), which permits unrestricted use, distribu- tion, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the creative commons license, and indicate if changes were made. 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( ), – ( ) . du, z., li, h., gu, t.: a state of the art review on microbial fuel cells: a promising technology for wastewater treatment and bio- energy. biotechnol. adv. , – ( ) . timmers, r.a., strik, d., hamelers, h.v.m., buisman, c.j.n.: electricity generation by a novel design tubular plant microbial fuel cell. biomass bioenergy , – ( ) publisher’s note springer nature remains neutral with regard to urisdictional claims in published maps and institutional affiliations. 	microbial fuel cell with a nano-membrane and two expired medicinal drug-feeding cathode: a novel strategy 	abstract 	introduction 	materials and methods 	chemicals and materials 	arrangement of medium and inoculum 	anodes and nano-membrane pretreatment 	depiction of the data procurement framework 	statistical analysis 	results and discussion 	mfc performance 	characterization of graphite electrode 	cod and bod removal efficiencies 	columbic efficiency 	conclusion 	acknowledgements 	references targeting sentinel proteins and extrasynaptic glutamate receptors: a therapeutic strategy for preventing the effects elicited by perinatal asphyxia? review targeting sentinel proteins and extrasynaptic glutamate receptors: a therapeutic strategy for preventing the effects elicited by perinatal asphyxia? mario herrera-marschitz & ronald perez-lobos , & carolyne lespay-rebolledo & andrea tapia-bustos & emmanuel casanova-ortiz & paola morales , & jose-luis valdes & diego bustamante & bruce k. cassels received: july /revised: august /accepted: august /published online: august # the author(s) . this article is an open access publication abstract perinatal asphyxia (pa) is a relevant cause of death at the time of labour, and when survival is stabilised, associ- ated with short- and long-term developmental disabilities, re- quiring inordinate care by health systems and families. its prevalence is high ( to / live births) worldwide. at present, there are few therapeutic options, apart from hypo- thermia, that regrettably provides only limited protection if applied shortly after the insult. pa implies a primary and a secondary insult. the primary insult relates to the lack of oxygen, and the secondary one to the oxidative stress triggered by re-oxygenation, formation of reactive oxygen (ros) and reactive nitrogen (rns) species, and overactivation of glutamate receptors and mitochondrial deficiencies. pa induces overactivation of a number of senti- nel proteins, including hypoxia-induced factor- α (hif- α) and the genome-protecting poly(adp-ribose) polymerase- (parp- ). upon activation, parp- consumes high amounts of atp at a time when this metabolite is scarce, worsening in turn the energy crisis elicited by asphyxia. the energy crisis also impairs atp-dependent transport, including glutamate re- uptake by astroglia. nicotinamide, a parp- inhibitor, pro- tects against the metabolic cascade elicited by the primary stage, avoiding nad+ exhaustion and the energetic crisis. upon re-oxygenation, however, oxidative stress leads to nu- clear translocation of the nf-κb subunit p , overexpression of the pro-inflammatory cytokines il- β and tnf-α, and glutamate-excitotoxicity, due to impairment of glial- glutamate transport, extracellular glutamate overflow, and overactivation of nmda receptors, mainly of the extrasynaptic type. this leads to calcium influx, mitochondrial impairment, and inactivation of antioxidant enzymes, increas- ing further the activity of pro-oxidant enzymes, thereby mak- ing the surviving neonate vulnerable to recurrent metabolic insults whenever oxidative stress is involved. here, we discuss evidence showing that (i) inhibition of parp- overactivation by nicotinamide and (ii) inhibition of extrasynaptic nmda * mario herrera-marschitz mh-marschitz@med.uchile.cl; mhmarschitz@gmail.com ronald perez-lobos ronald.perezlobos@gmail.com carolyne lespay-rebolledo carolynelespay@gmail.com andrea tapia-bustos ac.tapiabustos@gmail.com emmanuel casanova-ortiz emanuel.casanovao@gmail.com paola morales pmorales@med.uchile.cl jose-luis valdes jlvaldes@med.uchile.cl diego bustamante dbustama@med.uchile.cl bruce k. cassels bcassels@uchile.cl programme of molecular & clinical pharmacology, icbm, faculty of medicine, university of chile, av. independencia, po box , santiago, chile escuela de tecnologia medica, facultad de medicina, universidad andres bello, po box , santiago, chile faculty of sciences, university of chile, santiago, chile department of neuroscience, faculty of medicine, university of chile, santiago, chile neurotox res ( ) : – doi . /s - - - mailto:mhmarschitz@gmail.com http://crossmark.crossref.org/dialog/?doi= . /s - - - &domain=pdf receptor overactivation by memantine can prevent the short- and long-term consequences of pa. these hypotheses have been evaluated in a rat preclinical model of pa, aiming to identify the metabolic cascades responsible for the long-term consequences induced by the insult, also assessing postnatal vulnerability to recurrent oxidative insults. thus, we present and discuss evidence demonstrating that pa induces long-term changes in metabolic pathways related to energy and oxidative stress, priming vulnerability of cells with both the neuronal and the glial phenotype. the effects induced by pa are region dependent, the substantia nigra being particularly prone to cell death. the issue of short- and long-term consequences of pa provides a framework for addressing a fundamental issue re- ferred to plasticity of the cns, since the perinatal insult trig- gers a domino-like sequence of events making the developing individual vulnerable to recurrent adverse conditions, decreas- ing his/her coping repertoire because of a relevant insult oc- curring at birth. keywords neonatal hypoxia . hypoxic ischaemic encephalopathy (hie) . leukomalacia . basal ganglia . map- . gfap . tunel . nnos . delayed cell death . organotypic cultures . niacinamide . memantine . rat abbreviations adp adenosine diphosphate aif apoptosis inducing factor am calcein-acetoxymethyl ester ampa α-amino- -hydroxy- -methyl- - isoxazolepropionic acid as asphyxia-exposed rats atp adenosine triphosphate bca bicinchoninic acid bcl- b-cell lymphoma bnip bcl -interacting protein cns central nervous system cs caesarean-delivered rats cx neocortex cox- cyclooxygenase- d -amino- , -dimethyladamantane dapi ′ -diamidino- -phenylindole div days in vitro dna deoxyribonucleic acid dtnb , ′-dithiobis- -nitrobenzoic acid ethd- ethidium-homodimer- fda food and drug administration g gestation day gfap glial fibrillary acidic protein glast (eaat ) glutamate aspartate transport glt- (eaat ) glutamate transport- gpx glutathione peroxidase gsh reduced glutathione gssg oxidised glutathione h o hydrogen peroxide hie hypoxic-ischaemic encephalopathy hif- α hypoxia-induced factor- α i.p. intraperitoneal il- β interleukin β map- microtubule-associated protein- mk- dizocilpine nac n-acetylcysteine nad+ nicotinamide adenine dinucleotide nadph nicotinamide adenine dinucleotide phosphate nam nicotinamide, niacinamide, vitamin b nf-κb nuclear factor kappa-light-chain-enhancer of activated b cells nix bcl /adenovirus e b-interacting protein -like nmdar n-methyl-d-aspartate receptor nnos neuronal nitric oxide synthase no nitric oxide noxa phorbol- -myristate- -acetate-induced protein -ohda -hydroxydopamine onoo peroxynitrite anion p postnatal day pa perinatal asphyxia parp- poly(adp-ribose) polymerase- prx- peroxyredoxin- pvhl von hippel-lindau tumour-suppressing factor rfu relative fluorescence units rns reactive nitrogen species ros reactive oxygen species tnf-α tumour necrosis factor alpha th tyrosine hydroxylase tunel terminal deoxynucleotidyl transferase dutp nick end labelling the problem pregnancy culminates at the time when labour begins, imply- ing a complex interchange of molecules generated by uterine and extrauterine tissue, leading to increased myometrial con- tractility, cervical dilatation, decidual/membrane activation, and rupture of chorioamniotic membranes (romero et al. ). the switch from a quiescent to a contractile myometrium is accompanied by a shift from anti-inflammatory to pro- inflammatory signalling chemokines and cytokines, as well as contraction-associated proteins, warranting a successful deliv- ery (romero et al. ). delivery, however, can be a risky episode, whenever the onset of pulmonary respiration is neurotox res ( ) : – delayed or interrupted, leading to perinatal asphyxia (pa) if oxygenation is not promptly established or re-established. pa is a relevant cause of death at the time of labour, asso- ciated with long-term consequences when re-oxygenation is established (odd et al. ). despite important advances in perinatal care (kurinczuk et al. ; basovich ), pa remains a severe condition, with high prevalence ( to / live births) worldwide, also associated with long- lasting neuropsychiatric dysfunctions when children reach critical developmental stages (see douglas-escobar and weiss ). pa implies a deregulation of gas exchange resulting in hypoxemia, hypercapnia, and metabolic acidosis of vital or- gans, including the brain (low ). the interruption of oxygen supply causes energy failure, triggering a biochemical cascade leading to cell dysfunction and ultimately to cell death, particularly affecting neurocircuitries of the basal gan- glia and hippocampus (klawitter et al. ; morales et al. ; neira-peña et al. ). the long-term effects observed after pa also imply metabolic and neuronal network alter- ations, impairing the ability of the cns to cope with stressors occurring during life (see marriott et al. ). hypoxia leads to generation of reactive oxygen (ros) and reactive nitrogen (rns) species, inhibiting prolyl- hydroxylases that under normoxia metabolise the oxygen sen- sor hypoxia-inducible factor- alpha (hif- α). this is then poly-ubiquinated by von hippel-lindau tumour-suppressing factor (pvhl) and eliminated by the proteasome (wang et al. ). following the interruption of oxygen viability, hif- α accumulates and translocates to the nucleus, stimulating the expression of multiple genes associated with cell metabolism and mitochondrial function, down-regulating the citric acid cycle and enhancing anaerobic glycolysis, thus allowing the cells to cope with the low oxygen tension (ke and costa ; vangeison et al. ). hif- α translocation stimulates pro- apoptotic genes, including the bcl- family members nix, noxa, bnip , and apoptosis-inducing factor (aif) (bruick ; sowter et al. ) but also the expression of sentinel proteins, such as poly(adp-ribose) polymerase- (parp- ). parp- signalling occurs via the attachment of adp-ribose chains to nuclear proteins recognised by dna-repairing en- zymes, such as dna ligase iii. the generation of adp-ribose monomers requires, however, nad+, which is why parp- overactivation further depletes nad+ stores, resulting in pro- gressive atp depletion (berger ; hong et al. ). furthermore, there is tight crosstalk between parp- and hif- α (martin-oliva et al. ). under hypoxic conditions and/or oxidative stress, parp- modulates hif- α activity (martinez-romero et al. ). in turn, hif- α requires parp- activation for exerting its transcriptional activity (pan et al. ), while parp- activity protects the hif- α isoform against pvhl-mediated destabilization (gonzalez- flores et al. ). hypoxia implies a generalised impairment of na+/k+- atpase-dependent transport, including neurotransmitter re- uptake. a particular case is that of glutamate, which is largely synthesised by the astroglia-neuronal glutamine shuttle. it is not yet clear how atpase modulates glutamate transport. however, arachidonic acid inhibits several sodium-coupled amino acid transporters, including that of glutamate, by a mechanism requiring na+/k+-atpase (danbolt ). furthermore, there is evidence showing that extracellular glu- tamate levels are buffered by atp-dependent transport, to be taken up by glial and neuronal cells for metabolic degradation or re-cycling (herrera-marschitz et al. ). atp deficit de- creases glutamate uptake, resulting in increased extracellular glutamate levels. free radicals can also affect the members of the na+/cl−-dependent transporter family, although the role of oxidative modulation of glutamate uptake under normal con- ditions is not yet known, and even less under hypoxia (danbolt ). it has been shown, however, that glutamate transporters possess a sulfhydryl-based regulatory mecha- nism, which makes glutamate transporters sensitive to redox agents, resulting in increased or decreased transport (trotti et al. ). it is hypothesised here that under sustained hyp- oxia the half-life of extracellular glutamate is prolonged. this might provide an extreme homeostatic response for wide- spread neuronal depolarization removing the organism from a catastrophic condition by extracellular glutamate binding to any available glutamate receptor, mainly of the extrasynaptic subtype. the nmdars are heterotetramers composed by two nr (obligatory) and two nr / subunits (jacobucci and popescu ), whose gating and ligand-binding properties depend on the nr a/c subunit (glasow et al. ). the nr b-containing nmdars are extrasynaptic in a significant proportion (papouin et al. ). at birth, extrasynaptic nr b-containing receptors prevail over the nr a- containing nmdar subtype. the nr a-containing subtype is the predominant intrasynaptic mature nmdar, associated with long-term plasticity (see petralia ; vizi et al. ). the nr b subtype is associated with excitotoxic cascades and cell death, via ca + cellular entry and massive mitochon- drial ca + loading (loftis and janosky ; stanika et al. ). thus, sustained hypoxia necessarily implies excitotoxicity, worsening in turn the metabolic crisis and death if respiration is not promptly established. overstimulation of extrasynaptic nmda receptors in- creases nitric oxide (no) production, and further oxidative stress by formation of peroxynitrite upon its reaction with superoxide anions. no can directly decrease mitochondrial membrane potentials, liberating pro-apoptotic proteins (moncada and bolaños ), including aif, nadph oxi- dase, and neuronal nitric oxide synthase (nnos) (hwang et al. ), provoking dna fragmentation and mitochondrial fis- sion, maintaining a condition of high adp/atp ratio and en- ergy inefficiency (pérez-pinzon et al. ). mitochondrial neurotox res ( ) : – structure, function, and energy metabolism change over time, implicating that the physiology of mitochondria also evolves along the life span of an individual (mattson ). upon delivery and during neonatal and early developmen- tal stages, oxidative stress is a permanent risk for the develop- ing individual, enhanced by a sudden increase or decrease of metabolism associated with development itself or environment-dependent conditions, including malnutrition, fatigue, fever, infections, trauma, and/or inflammation- inducing injuries (deng ). oxidative stress produces an imbalance that favours the production of ros over antioxi- dant defences (orrenius et al. ), with hydrogen peroxide (h o ) playing a pivotal role (sies ). at low concentra- tions ( – nm), h o leads to adaptative stress responses, while above μm h o induces inflammation, growth arrest, and cell death (deng ; aschbacher et al. ). an experimental model of global pa in rats in our laboratory, we established an experimental model of global pa in rats, originally proposed by borje bjelke, kurt andersson, and collaborators at the karolinska institutet, stockholm, sweden, in the s (bjelke et al. ; andersson et al. ; herrera-marschitz et al. ). in this model, hypoxia occurs at the time when the rats are ready for or have begun delivery. the model has been pivotal for the study of relevant targets responsible for metabolic cascades leading to long-term effects (see herrera-marschitz et al. , ; recently reviewed by barkhuizen et al. ). the model starts by a programmed mating. at the time of pro-oestrus, a female wistar rat is exposed to a male for one night, looking the next day for a vaginal clot to exactly predict the time of delivery ( days). when on term, a first sponta- neous delivery is observed before the dam is neck-dislocated and subjected to hysterectomy to remove the foetus- containing uterine horns, which are immersed in a water bath at °c for min in order to induce severe asphyxia. the foetuses are manually delivered and stimulated to start breath- ing, and after a nursering period, the pups are given to surro- gate dams pending further experiments. sibling, spontaneous, or caesarean-delivered pups are used as controls (see herrera- marschitz et al. ). the model allows monitoring early or delayed long-lasting molecular, metabolic, and physiological effects, or the pups can also be used to prepare organotypic cultures (morales et al. ; klawitter et al. ). pa is a menace to the full organism, affecting systemic and brain tissue. the availability of atp is rapidly decreased in the kidneys, already after min of pa, whereas brain atp is de- creased to less than % after min of asphyxia if performed at °c (engidawork et al. ). heart metabolism is sustained until the time when the lack of oxygenation is incom- patible with life, largely supported by the bphosphocreatine shuttle^ (friedman and roberts ), which is not useful for the neonatal brain (lubec et al. ), although there is some clinical evidence showing that a creatine-supplemented diet protects the newborn from birth hypoxia (ireland et al. , ; tachikawa et al. ), but further research is certainly required to evaluate the phosphocreatine shuttle in the developing brain. pa implies a primary and a secondary insult. the primary insult relates to the lack of oxygen, and the secondary one to the oxidative stress triggered by re-oxygenation, resulting in the formation of ros and rns, and overactivation of gluta- mate receptors and mitochondrial deficiencies, as recently discussed (hagberg et al. ). the hypoxic insult the brain is vulnerable to a decrease of blood oxygen satura- tion, due to its high dependence on aerobic metabolism. whenever hypoxia is sustained, there is a switch to glycolysis, a poor metabolic alternative because of the low glucose stores in newborn brain tissue and deficient atp output by the gly- colysis pathway, resulting in lactate accumulation and acidosis (engidawork et al. ). the cerebral energy metabolism of newborn rodents and humans can utilise ketone bodies β- hydroxybutyrate and acetoacetate rather than glucose to satis- fy cerebral energy requirements (see nehlig and pereira de vasconcelos, ). in neonates, these ketone bodies are es- sential energy sources, produced by liver mitochondria and diffusing to other organs including the brain. ketone uptake into the brain of the newborn is four to five times faster than that in older babies or infants (cunnane and crawford ). in adults, ketones can provide the energy requirements follow- ing prolonged fasting or starvation (wang et al. ), and are also the main source of carbon to make cholesterol and long- chain fatty acids, important structural lipids for the developing brain (cunnane et al. ). it is not yet known, however, if ketone bodies can compensate for the energy crisis elicited by hypoxia during the perinatal period. the re-oxygenation insult re-oxygenation is a requirement for survival, leading neces- sarily to oxidative stress and free radical formation, excitotoxicity, intracellular calcium accumulation, mitochon- drial dysfunction, and inactivation of buffering enzymes, resulting in a metabolic deficient condition, increasing cns vulnerability to recurrent metabolic insults. oxidative stress and free radical formation lead to inhibi- tion of na+-dependent glutamate uptake by astroglial cells, the main mechanism regulating extracellular glutamate levels (herrera-marschitz et al. ; see anderson and swanson neurotox res ( ) : – ) implicated in short- and long-term excitoxicity, as discussed by herrera-marschitz and schmidt ( ). the im- pairment of glial-glutamate transport leads to extracellular glutamate overflow. if not taken up, glutamate binds to extrasynaptic nmdars, expressing at neonatal stage ca +-permeable nr b and mg +-insensitive nr a nmdar subunits (massey et al. ; see groc et al. ; hardingham and bading ; jantzie et al. ; also, papouin et al. ). overstimulation of extrasynaptic nmdar increases ca + influx, triggering mitochondrial dysfunction and ros and rns formation (starkov et al. ; stanika et al. ), modifying lipids and macromolecules, such as proteins and nucleic acids (see quincozes-santos et al. ). there is evidence that nmda receptor blockage improves mitochondrial respiration, preventing mitochondrial permeabilization during the reperfu- sion phase following hypoxic-ischaemic injury (block and schwarz ; chen et al. ; puka-sundvall et al. ). ros and rns levels can overwhelm the capacity of cellu- lar defence systems. ros introduce post-translational oxida- tive carbonyl modifications on macromolecules (lourenco dos santos et al. ), while s-nitrosylation modifies reac- tive cysteine thiol on target proteins, leading to both protein misfolding and fission/fusion-dependent mitochondrial dys- function and fragmentation (nakamura and lipton ). parp- is further activated (duan et al. ; abramov and duchen ), and aif is translocated, triggering caspase- independent apoptosis (see krantic et al. ). ros alter iκb degradation, resulting in nf-κb activation, and nuclear translocation of the p subunit, which is increased in a parp- -dependent manner by pa (neira-peña et al. ). the global perinatal insults trigger inflammatory signalling in peripheral and brain tissues, implicating also vascular integri- ty. cyclooxygenase- (cox- ), a marker of inflammation, is transiently elevated in rat brain exposed to pa, together with up- and subsequent down-regulation of antioxidant enzymes (toti et al. ; bonestroo et al. ). this suggests delayed vulnerability that could contribute to developmental abnor- malities responsible for the behavioural alterations observed after pa (piscopo et al. ), also in the ischaemic neona- tal human brain (toti et al. ). at neonatal stages, the effect of increased ros and rns is aggravated by imma- ture defence mechanisms, including low expression/ activity of the superoxide dismutase (sod) family, gluta- thione peroxidase (gpx) (samarasinghe et al. ), cata- lase (lafemina et al. ), and peroxyredoxin- (prx- ) (chang et al. ). prx- is exclusively located in mito- chondria, co-localising with sod- (mn-sod) (watabe et al. ; cao et al. ). prx- protects against peroxynitrite anions (hattori et al. ; see hanschmann et al. ), and it is expressed heterogeneously, correlat- ing with a regional sensitivity to excitotoxic damage (hattori et al. ; aon-bertolino et al. ). current brain-protecting strategies therapeutic options against the long-term effects of pa are limited and mainly based on hypothermia, which provides protection only if initiated soon after the insult (thoresen et al. ). no consensus on clinical protocols has been achieved yet, and the advantages and disadvantages of head or whole body cooling are still debated, including safety and developmental considerations (committee on fetus & newborn ; allen ; shankaran et al. ; sabir and cowan ; ahearne et al. ). hypothermia there is compelling clinical evidence that cerebral hypother- mia improves the neurodevelopmental outcome when applied to infants with moderate to severe hypoxic-ischaemic enceph- alopathy (hie), before the onset of a secondary deterioration phase (edwards et al. ; guillet et al. ; shankaran et al. ; see wassink et al. ; vanlandingham et al. ). this has led to a recommendation supported by the european resuscitation council that any new therapeutic ap- proach dealing with neonatal encephalopathy should be com- pared to the effect produced by hypothermia (davidson et al. ; gunn and thoresen ). as mentioned above, the current hypothermia protocols are still insufficient (allen ), and a main drawback is the existence of a narrow therapeutic window (odd et al. ; sabir and cowan ; ahearne et al. ). the rationale of hypothermia is graded reduction of cerebral metabolism, about % for every degree celsius of temperature reduction (laptook et al. ; erecinska et al. ). cooling also reduces post-depolarization release of excitatory amino acids during hypoxia-ischaemia, both in newborn (thoresen et al. ) and in adult (nakashima and todd ) subjects. microdialysis experiments showed that hypothermia initiated immediately after hypoxia-ischaemia in newborn piglets was associated with reduced levels of excitatory amino acids and reduced no efflux compared to the control condition (thoresen et al. ; rostami et al. ), in agreement with evidence that glutamate antagonists can also prevent events occurring in the early recovery phase following hypoxia-is- chaemia, before failure of mitochondrial function takes place, but only when the effect of the antagonist is associated with hypothermia (nurse and cobertt ). parp- overactivation parp- plays a critical role during development, and is acti- vated upon any threat to the genome, either for its repair or for initiating cell death signalling to protect its integrity. indeed, neurotox res ( ) : – parp- overactivation elicits a nmdar-dependent, caspase- independent, parthanatos-like cell death programme (wang et al. ) and pa increases parp- activity in the rat brain shortly after the insult (allende-castro et al. ), triggering a signalling cascade leading to nuclear translocation of the nf-κb subunit p and the expression of the pro- inflammatory proteins il- β and tnf-α, increasing cell death (neira-peña et al. ). such effects are prevented by the parp- inhibitor nicotinamide, supporting previous re- ports showing similar protection against neuronal death (klawitter et al. ), brain dopaminergic dysfunction (bustamante et al. ), and behavioural deficits (simola et al. ; morales et al. ) assessed – months after the perinatal insult. parp- inhibition attenuates nnos acti- vation and reduces cell death induced by oxidative conditions (pieper et al. ; klawitter et al. ), restoring metabolic functions including energy production (chen et al. ; xu et al. ). nicotinamide, as an nad+ precursor, probably protects against the metabolic cascade elicited by the primary insult, avoiding nad+ exhaustion and the energy crisis. while the hypothesis of parp- inhibition is promising, it has yet to reach a consensus in order to attempt a clinical trial, in part because nicotinamide does not provide full protection against the effects elicited by pa. nicotinamide prevents vul- nerability to recurrent metabolic insults, but mainly in the substantia nigra, with only minor effects in the neocortex and neostriatum (neira-peña et al. ; perez-lobos et al. ). the issue of analogues, precursors, or metabolites of nicotinamide is attractive (trammell et al. ), recently discussed in relation to nicotinamide riboside, which improves mitochondrial and stem cell function, prolonging the life span of mice (zhang et al. ). nicotinamide mononucleotide has been shown to be supe- rior to nicotinamide as a precursor of nad+ (kawamura et al. ), leading to the proposal that nicotinamide mononucle- otide protects from energy deficits by restoring nad+ and atp levels, reducing ros accumulation (wang et al. ). the oral bioavailability of nicotinamide mononucleotide has been reported, and this intermediate mitigates age-associated physiological decline in mice without any obvious toxicity or deleterious effects, enhancing mitochondrial oxidative metab- olism and preventing mitonuclear protein imbalance (mills et al. ). it is not yet known whether nicotinamide riboside or mononucleotide can also decrease parp- overactivation, or whether they can prevent the long-term consequences of pa. glutamate excitotoxicity the involvement of glutamate in excitotoxicity-mediated damage induced by metabolic insults, including stroke, is- chaemia, and hypoxia, led to the strategy of treating with selective high-affinity nmda and/or ampa antagonists, all of which failed in clinical trials (cheng et al. ). the classical non-competitive nmdar antagonist dizocilpine (mk- ) gave hope for death prevention following pa (herrera-marschitz et al. , ; engidawork et al. ), but it was largely surpassed by hypothermia. it was also discussed whether the minor protection provided by mk- is explained by a hypothermia-induced effect (buchan and pulsinelli ; see alkan et al. ; makarewicz et al. ). several glutamate transporter proteins are expressed by as- trocytes, mainly glast (eaat ) and glt- (eaat ) sub- types, responsible for the majority of glutamate uptake (see robinson and jackson ), providing a target for increasing or decreasing extracellular glutamate levels (herrera- marschitz et al. ). n-acetylcysteine, a clinically established antioxidant, has been shown to activate the cystine/glutamate antiporter, modulating extracellular gluta- mate levels (danbolt ; see berk et al. ). the actual direction of the transport of cystine or glutamate depends upon the intracellular and extracellular concentration of the respec- tive molecules. several clinical studies have shown that n- acetylcysteine is well tolerated, promising a role for the treat- ment of a number of neuropsychiatric disorders (wink et al. ; see berk et al. ). in the brain, n-acetylcysteine is deacetylated and oxidised to cystine, which is reduced back to cysteine when taken up by the cells, playing a role in the synthesis of glutathione (gsh) (bavarsad shahripour et al. ). thus, n-acetylcysteine is perhaps an option to be tested in the present model (see quintanilla et al. ). memantine as a lead for a neonatal protecting strategy d ( -amino- , -dimethyladamantane), better known as memantine, was first proposed as a putative anti-parkinsonian drug in the s, since it induced rotational behaviour in uni- laterally -ohda-lesioned animals with a profile mimicking that of d-amphetamine and apomorphine, indirect and direct dopamine agonists respectively (danysz et al. ; see herrera-marschitz et al. , ). this was confirmed by seeman et al. ( ), demonstrating the action of memantine on dopamine d receptors. nevertheless, the main pharmaco- dynamic feature supporting a clinical application in stroke, is- chaemia, or neurodegenerative disorders was based on the ob- servation that memantine is a low-affinity, use-dependent, nmdar channel blocker with fast kinetics, not interfering with normal synaptic transmission, but blocking nmdar only when it is overstimulated (volbracht et al. ; rammes et al. ). memantine is considered at present as a prototype for targeting extrasynaptic nmdr activity (garcia-munoz et al. ; johnson et al. ). neurotox res ( ) : – memantine is well tolerated and has a low incidence of adverse effects (kavirajan ), also inducing mild hypo- thermia (krieglstein et al. ), a feature further supporting its clinical potential (see rammes et al. ). memantine has been approved by the european medicine agency and the food and drug administration (fda-usa) for the treatment of moderately severe alzheimer’s disease ( ). it has been reported that memantine can reduce functional and morpho- logical sequelae induced by ischaemia (block and schwarz ; chen et al. ; volbracht et al. ), possibly by selectively blocking extrasynaptic nmdar (chen et al. ; xia et al. ; garcia-munoz et al. ). memantine has also been evaluated for efficacy in chil- dren with pervasive developmental disorders, including leukomalacia, while there is still concern about increas- ing constitutive apoptosis, recommending further pre- clinical investigation (manning et al. ). an important issue refers to whether memantine prevents the excitotoxic cascade elicited by pa. this question merits investigation, either with memantine alone and/or together with the parp- inhibitor nicotinamide, to assess prevention of the short- and long-term effects elicited by pa, profiting also from the mild hypothermia induced by memantine (krieglstein et al. ; gunn and thoresen ). memantine can improve mitochondrial respiration, preventing mitochondrial perme- abilization during the secondary (reperfusion) phase following hypoxic-ischaemic injury (block and schwarz ; chen et al. ; pirinen et al. ; olah et al. ), in agreement with a pivotal role of extrasynaptic nmda receptors in the effects elicited during the re-oxygenation phase following hypoxia. the chemical structure of memantine ( , - dimethyltricyclo[ . . . , ]decan- -amine) allows addi- tional groups to be attached to increase selectivity, improving its pharmacodynamic and/or pharmacokinetic properties. hence, nitromemantine has been synthesised, by attaching a nitrate group to produce -amino- , -diethyladamantan- -yl nitrate. this no source improved efficacy as a neuroprotectant, compared to that provided by memantine, by nitrosating a redox-mediated regulatory site on the extrasynaptic nmda receptor (lipton ; takahashi et al. ; see nakamura and lipton ). hypothermia and excitatory amino acid blockage can pro- vide a potent synergism for prevention of the secondary ener- getic mitochondrial-related failure associated with pa. nevertheless, many of the compounds used for blocking the initial phases of injury, excitotoxicity, and oxidative stress elicited by hypoxic-ischaemic encephalopathy failed, also be- cause of blockage of normal functions associated to gluta- matergic signalling. mk- decreases death following pa (peruche and krieglstein ; herrera-marschitz et al. , ), but it also induces apoptosis, impairing brain development in rats (ikonomidou et al. ). vulnerability to recurrent metabolic insults neonatal metabolic insults may lead to immediate and/or de- layed consequences, with clinical onset at different develop- mental stages. understanding the sequence of these events is still sketchy. nevertheless, it has been discussed that metabol- ic insults occurring at birth (a first hit) can prime development, increasing the vulnerability to recurrent (secondary and tertia- ry hit) insults, ultimately challenging postnatal development and maturity. in humans, pa is a risk factor for several psy- chiatric disorders, including learning deficits and schizophre- nia. conversely, in rodents, pa is associated with delayed cell death, dopamine and histamine transmission deficits and be- havioural impairments assessed at adulthood, affecting learn- ing, spatial, and non-spatial memory and anxiety (simola et al. ; morales et al. ; galeano et al. , ; flores- balter et al. ; tapia-bustos et al. ). the idea of pro- gressive dysfunction and bfirst^ and successive hit sequences, triggering and perpetuating pathophysiological conditions and/or diseases, has recently been discussed (marriott et al. ; israel et al. ). in agreement with this, it was recent- ly reported that pa implies a long-term energy deficit and oxidative stress, evaluated by the adp/atp and gsh/gssg ratio, respectively, prevented by nicotinamide (perez-lobos et al. ). figure shows the effect of pa and a recurrent metabolic insult ( mm h o ) on adp/atp (fig. a), gsh/ gssg (fig. b), and potassium ferricyanide-reducing power (fig. c) measurements on entire sample homogenates from triple organotypic cultures from caesarean-delivered and asphyxia-exposed rat neonates, making it evident that pa pro- duces a permanent energy deficit (increased adp/atp ratio) and oxidative stress (decreased gsh/gssg ratio), as well as a permanent deficit in reducing antioxidant power, increasing vulnerability to recurrent insults (perez-lobos et al. ) conclusions the present review focuses on the short- and long-term met- abolic cascades triggered by pa, identifying pathways that can explain long-term vulnerability and clinical consequences. the karolinska institutet model of pa has recently been discussed by a review summarising years of research on global asphyxia in the immature rat brain (barkhuizen et al. ). pa is still a prominent clinical issue with few therapeutic alternatives preventing its long-term consequences. we have established a unique experimental model of global pa in rats occurring at the time of delivery, identifying relevant targets responsible for metabolic cascades leading to short- and long- term effects, evaluated by in vivo and in vitro experiments (see herrera-marschitz et al. , ). the model is a referent among those used for studying progressive neurological neurotox res ( ) : – dysfunction originating early in life (marriot et al. ). pa constitutes a model of neural damage and regeneration for many other conditions such as stroke, where hypoxia/ ischaemia is often followed by re-oxygenation and injury. the discussed model has been compared to that of hypoxia/ischaemia proposed by rice et al. ( ) (vannucci and vannucci ; vannucci et al. , ), marshalling the fact that the reviewed model is performed with on-term and not with neonates at p , the former being premature when compared to the neonatal human brain. the prematurity of the neonatal rat brain has been a subject of controversy, arguing that the degree of maturity depends upon the tissue and the functions selected for comparison (herrera-marschitz et al. ). further, the model of vannucci and collaborators in- volves ligation of vessels, resulting in a pathophysiology equivalent to focal stroke, not necessarily triggered by global asphyxia (fellman and raivio ). the here discussed model (i) is a good mimic of human delivery (romero et al. ); (ii) it is largely non-invasive, not involving vessel li- gation, ischaemia, or exposure of pulmonary breathing ani- mals to n inhalation chambers (fellman and raivio ); (iii) it allows evaluation of short- and long-term consequences of the insult, monitored in the same preparation (kohlhauser et al. a, b; simola et al. ; morales et al. ); (iv) it is highly reproducible among laboratories (lubec et al. a, b); and (v) it is considered as a reference by worldwide leading labs (see wassink et al. ; gunn and thoresen ). furthermore, (vi) the model is unique in providing a bridge between in vivo and in vitro experiments, based on the same preparation. indeed, foetuses and neonates can be used to prepare organotypic cultures, complementing and/or allowing experiments with bioethical restrictions when performed in vivo, such as exposing surviving neonates to a recurrent insult (perez-lobos et al. ). the organotypic culture model originally developed by bh gahwiler in zurich ( ) was validated by plenz and kitai ( a, b; plenz et al. ), as a powerful tool for studying rat basal ganglia neurocircuitries. in this model, the pattern of neuronal innervation and neurocircuitry formation is moved back to an earlier stage, providing an opportunity to monitor under the microscope how neurites and processes look for their corresponding targets, establishing innervation plexuses, showing electrophysiological (plenz and kitai b) and neurochemical (gomez-urquijo et al. ) features similar to those observed in vivo. the model has been used to dem- onstrate the effect of pa on the number and branching of tyrosine-hydroxylase-positive neurons, illustrating the vulner- ability of the dopaminergic systems to pa (morales et al. ; klawitter et al. , ). we have recently reported that the organotypic model allows evaluation of the effect of pa on postnatal vulnerability to oxidative stress, demonstrat- ing an additive effect to that produced by pa on cells with neuronal and glial phenotype, prevented by systemic nicotin- amide treatment h after birth (perez-lobos et al. ). pa provides a framework to address a fundamental issue affecting long-term cns plasticity. the perinatal insult trig- gers a domino-like sequence of events making the developing fig. adp/atp (a), gsh/gssg (b), and )c) potassium ferricyanide- reducing power measurements on entire sample homogenates from triple organotypic cultures. a adp/atp ratio observed in cultures at days in vitro (div) from caesarean-delivered (controls; cs) (open columns) and asphyxia-exposed (as) (hatched columns) rat neonates (p ) (means ± sem; n = , for each experimental groups). b gsh/gssg ratio. c potassium ferricyanide-reducing power. ap < . for the effect of asphyxia (cs + sal versus as + sal); bp < . for the effect of h o (cs + sal + mm h o versus cs + sal + mm h o , or as + sal + mm h o versus as + sal + mm h o ). cp < . , for the effect of nicotinamide (nam) (cs + sal + mm h o versus cs + nam + mm h o ; cs + sal + mm h o versus cs + nam + mm h o ; as + sal + mm h o versus as + nam + mm h o ; as + sal + mm h o versus as + nam + mm h o ) (data from perez-lobos et al. ) neurotox res ( ) : – individual vulnerable to recurrent adverse conditions, decreas- ing his/her coping repertoire because of a relevant insult oc- curring at birth (marriott et al. ). the issue of the short- and long-term consequences of pa has heuristic relevance, since pa implicates a long-term biological vulnerability that fully depends on the severity of an insult occurring at birth, independently of any genetic or clinical predisposition (sahin and sur ; jain et al. ). indeed, by definition, pa (an environmentally dependent variable) refers to an unexpected interruption of oxygen at the time of delivery, when labour has already begun. therefore, no genetic factor, malformation, or prematurity is included in the clinical entity of pa, which is defined as a specific metabolic/energetic insult related, first, to the delay and/or interruption of autonomous breathing, and, second, to re-oxygenation, a requirement for survival. andersson k, bjelke b, bolme p, Ögren s-Ö ( ) asphyxia-induced lesion of the rat hippocampus (ca , ca ) and the nigro-striatal dopamine system. in: gross j (ed) hypoxia and ischemia. cns. 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cytoplasmic vacuolation following post-ischemic administration and do not block maze learning or long-term poten- tiation. neuroscience : – neurotox res ( ) : – acknowledgements contract grant sponsors: fondecyt-chile (# ); millennium scientific initiative (bni p - -f); mh- marschitz foundation, sweden. rpl (# ), clr (# ), atb (# ), and ep (# ) are conicyt-chile fellows. vvm was a mecesup-chile fellow (uch ). compliance with ethical standards conflict of interest the authors declare that they have no conflict of interest. open access this article is distributed under the terms of the creative commons attribution . international license (http:// creativecommons.org/licenses/by/ . /), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appro- priate credit to the original author(s) and the source, provide a link to the creative commons license, and indicate if changes were made. references abramov ay, duchen mr ( ) mechanisms underlying the 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rats 	the hypoxic insult 	the re-oxygenation insult 	current brain-protecting strategies 	hypothermia 	parp- overactivation 	glutamate excitotoxicity 	memantine as a lead for a neonatal protecting strategy 	vulnerability to recurrent metabolic insults 	conclusions 	references wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ optimization of heterotrophic cultivation of chlorella sp. for oil production optimization of heterotrophic cultivation of chlorella sp. for oil production tonghui xie, yuan sun, kaifeng du, bin liang, rong cheng, yongkui zhang ⇑ department of pharmaceutical & biological engineering, school of chemical engineering, sichuan university, chengdu, , pr china h i g h l i g h t s " a novel microalga chlorella sp. lam-h had a great potential to product lipid. " central composite design was used to optimize cultivation factors for bio-oil. " the interactions between temperature and medium components were investigated. " the model was found to be excellent in predicting the lipid productivity. " the lipid productivity reached . mg l� d� , higher than other reports. a r t i c l e i n f o article history: received january received in revised form april accepted may available online may keywords: chlorella sp. lipid production optimization response surface methodology a b s t r a c t the oleaginous microalga chlorella sp. lam-h screened from freshwater was proven to be a prospective feedstock for oil production according to its fatty acid composition. in order to enhance lipid production, response surface methodology (rsm) was used with central composite design (ccd) to optimize the het- erotrophic cultivation of microalgae. the experiment results showed that a satisfactory second-order polynomial regression equation was achieved with a high coefficient of determination (r = . ) in analysis of variance. the effects of individual factors and their interactions on lipid productivity were suc- cessfully revealed. the greatest lipid productivity reached . mg l� d� under the optimal condi- tions of glucose concentration . g l� , sodium nitrate concentration . g l� and temperature . �c. moreover, validation tests were performed and the results were very close to the predicted val- ues. it was demonstrated that the obtained model was effective for predicting lipid productivity of the isolated microalga. � elsevier ltd. all rights reserved. . introduction nowadays, the environmental problem is increasingly serious because of the overuse of non-renewable fossil fuels (such as petroleum, coal and natural gas) (balat, ). to alleviate energy crisis and reduce environmental pollution, great efforts have been made to exploit alternative fuels. in this context, microalgae, as one of the biomass energy resources, have attracted considerable attention with advantages of fast growth, short production cycle, efficient oil production and low environmental demand (guanhua et al., ; hong et al., ). in particular, chlorella sp. was re- ported to be potentially used as a candidate for biodiesel produc- tion (hsieh and wu, ; miao and wu, ). however, microalgal cultivation, especially in large scale, is discouraged by low cell density and high light requirement. hence, the search for the approach to overcome these drawbacks is well expected for more efficient microalgal cultivation. in comparison with photoautotrophy, heterotrophic cultivation allows microalgae to accumulate higher proportion of lipid within less time, and the scale-up process is much easier (bumbak et al., ; mohamed et al., ). thus, it offers a potential pathway to produce lipid for large scale biodiesel production. nevertheless, the production cost of biodiesel produced from microalgae is much higher than that of diesel derived from petroleum, due to the low efficiency of cultivation process (cheng et al., ). during the process, the lipid production rate is significantly affected by several factors, such as temperature, concentrations of carbon and nitro- gen (brennan and owende, ; dean et al., ; queiroz et al., ). therefore, it is necessary to study the optimal condi- tions of heterotrophic cultivation to achieve high lipid productivity. to develop the process technology in microalgal cultivation, single-factor experiment was applied to optimize the cultivation conditions of microalgae (ruangsomboon, ). however, the tra- ditional method is time-consuming and has a poor performance for optimizing a large number of parameters. besides, it might lead to erroneous conclusions, since interactions between factors are - /$ - see front matter � elsevier ltd. all rights reserved. http://dx.doi.org/ . /j.biortech. . . ⇑ corresponding author. tel.: + ; fax: + . e-mail address: zhangyongkui@scu.edu.cn (y. zhang). bioresource technology ( ) – contents lists available at sciverse sciencedirect bioresource technology j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / b i o r t e c h http://dx.doi.org/ . /j.biortech. . . mailto:zhangyongkui@scu.edu.cn http://dx.doi.org/ . /j.biortech. . . http://www.sciencedirect.com/science/journal/ http://www.elsevier.com/locate/biortech aalborg universitet solar photovoltaic power plants islam, md. rabiul ; wu, xuan; guo, younguang; ma, ke published in: international journal of photoenergy doi (link to publication from publisher): . / / creative commons license cc by . publication date: link to publication from aalborg university citation for published version (apa): islam, m. r., wu, x., guo, y., & ma, k. ( ). solar photovoltaic power plants. international journal of photoenergy, [ ]. https://doi.org/ . / / general rights copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. ? users may download and print one copy of any publication from the public portal for the purpose of private study or research. ? you may not further distribute the material or use it for any profit-making activity or commercial gain ? you may freely distribute the url identifying the publication in the public portal ? take down policy if you believe that this document breaches copyright please contact us at vbn@aub.aau.dk providing details, and we will remove access to the work immediately and investigate your claim. downloaded from vbn.aau.dk on: april , https://doi.org/ . / / https://vbn.aau.dk/en/publications/ec c d - f d- fb- -f a ef dc https://doi.org/ . / / editorial solar photovoltaic power plants md. rabiul islam, wei xu, youguang guo, and ke ma rajshahi university of engineering and technology, rajshahi, bangladesh huazhong university of science and technology, wuhan, china university of technology sydney, ultimo, nws, australia aalborg university, aalborg, denmark correspondence should be addressed to md. rabiul islam; rabiulbd@hotmail.com received april ; accepted april ; published june copyright © md. rabiul islam et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. in , the global primary energy consumption was , . million tons of oil equivalent which generates about , million tons of carbon during the burning of fossil fuels. the global energy crisis and environmental degrada- tion problems have led to the rapid development of solar photovoltaic (pv) power plants to replace conventional power plants. solar pv power plants of more than mw in capacity have thereby become a reality. future solar pv power plants will have higher power capacity. indeed, some of them will exceed mw. up to , about installations worldwide were pv power plants larger than mw. a mw solar pv power plant may save about , tons of co emissions per annum. more than % of the installed capacity consists of grid-connected systems. since multimegawatt pv power plants require large areas of land, they are usually installed in remote areas, far from cities. for power transmission, a medium voltage network is commonly used. the power converter topology, system stability, and control of grid-connected pv power plants have attracted considerable interest in recent years, as the existing technol- ogies are not suitable for large-scale pv power plants yet. in the last two decades, extensive research has been carried out in proposing new inverter topologies. besides the devel- opment of inverter topologies, considerable efforts have also been directed toward the progress of maximum power point tracking algorithms and grid stability and control, due to the intermittent nature of solar energy source. in order to push this emerging technology, more research is needed to solve two enormous challenges, that is, energy and environ- ment by replacing conventional power plants with solar pv power plants. we received a total of manuscripts, of which were selected for publication on various aspects of pv through the strict experts’ peer reviews. a brief description and salient results of the papers to be published in the special issue are given below. the paper “modeling and analysis of new multilevel inverter for solar photovoltaic power plant” by x. guo et al. explores a novel five-level inverter for the high-voltage pv power plant applications. the model of the inverter is analyzed. with the redundant switching states, a new modu- lation strategy is proposed to reduce the common-mode volt- age and electromagnetic interference. o. p. akkaş et al.’s paper “optimal site selection for a solar power plant in the central anatolia region of turkey” describes the criteria for selecting the appropriate location of solar pv power plants by the multicriteria decision-making methods. the results are evaluated for cities in the central anatolian region of turkey. the paper by c. mu et al. entitled “observer-based load frequency control for island micro- grid with photovoltaic power” investigated the load fre- quency control of an island microgrid with pv power and electric vehicles (evs), where the evs can be treated as distributed energy storages. considering the disturbances from load change and pv power, an observer-based integral sliding mode controller is designed to regulate the frequency back to the prescribed value, where the neural network hindawi international journal of photoenergy volume , article id , pages https://doi.org/ . / / https://doi.org/ . / / observer is used to estimate online the pv power. research paper “synergetic control of grid-connected photovoltaic systems” by j. qian presents synergetic control for the con- trol of a grid-connected pv system. modeling of a grid- connected pv system is described, and differential-algebra equations are obtained. two control strategies are used in normal operation and during low-voltage ride-through of a pv system. practical synergetic controllers with two control strategies are synthesized. the mathematical expressions are derived for computing control variables. in paper by o. taşkın et al. entitled “analysis on photovoltaic energy- assisted drying of green peas”, a pv energy-assisted indus- trial dryer has been tested in various weather and working conditions. a. jahid et al.’s paper “pv-powered comp- based green cellular networks with a standby grid supply” proposes a novel framework for pv-powered cellular net- works with a standby grid supply and essential energy man- agement technique for achieving envisaged green networks. the proposal considers an emerging cellular network archi- tecture employing two types of coordinated multipoint (comp) transmission techniques for serving the subscribers. under the proposed framework, each base station is powered by an individual pv solar energy module having an indepen- dent storage device. the paper by h. a. hussein et al. entitled “improving the hybrid photovoltaic/thermal system performance using water-cooling technique and zn-h o nanofluid” is devoted to an enhancement of the performance of pv panel under different operating conditions. a new design of active cooling technique is constructed which con- sists of a small heat exchanger and water circulating pipes placed at the pv rear surface to solve the problem of high heat stored inside the pv cells during the operation. we hope that this issue will promote new research direc- tions to address the undergoing challenges and technological requirements in solar pv power plants. acknowledgments we would like to take this opportunity to thank all the authors who are interested in publishing their articles in this special issue. our specific thanks will be to the editorial board members of this journal; without their help and contribution, this issue will never be concluded in due course. md. rabiul islam wei xu youguang guo ke ma international journal of photoenergy submit your manuscripts at https://www.hindawi.com hindawi publishing corporation http://www.hindawi.com volume inorganic chemistry international journal of hindawi publishing corporation http://www.hindawi.com volume international journal ofinternational journal of photoenergy hindawi publishing corporation http://www.hindawi.com volume carbohydrate chemistry international journal ofinternational journal of hindawi publishing corporation http://www.hindawi.com volume journal of chemistry 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https://dro.dur.ac.uk/policies/usepolicy.pdf https://dro.dur.ac.uk 	 	 cities and planetary repair: the problem with climate retrofitting dr. sarah knuth department of geography durham university in the s, major us initiatives framed urban retrofitting as a decarbonization solution. these programs address an obtrusive legacy of industrial capitalism: its built environments shed energy and emissions when they fall into disrepair. political ecology and economy have been slow to engage retrofitting, an absence that is conspicuous as these fields take on planetary repair as a conceptual provocation and turn in mainstream conservation. this paper explores us retrofitting as a distinctive material repair practice, one born as an energy poverty program amid the scarcity fears of the s energy crisis but seeing a renaissance today as a program for green capitalist growth. i interrogate two economies of repair now emerging around retrofitting, energy market and cleantech aspirations to make energy efficiency a resource and articulated efforts to sell retrofits as new green value for real estate development and investment. such urban revaluation efforts join an expanding array of green gentrification schemes today. paradoxically, even as would-be green entrepreneurs are drawn to these seemingly intangible and “clean” forms of waste and value-in-waiting, retrofitting presents intransigent materialities. its decarbonization ambitions demand not just profit-generating urban repair today but large-scale urban maintenance into the future. this need confronts longstanding efforts to render us cities and built environments flexible to recurrent creative destruction in service of ongoing economic growth. such logics of de/revaluation and essential disposability permit concurrent us programs for gentrification and urban abandonment today. however, decarbonization requires a more substantial confrontation with capitalist ruination-as-usual. keywords: retrofitting, planetary repair, green growth, green gentrification, political ecology/economy in the s, major us initiatives framed urban retrofitting as a decarbonization solution. these programs address an obtrusive legacy of industrial capitalism: its built environments shed energy and emissions when they fall into disrepair. political ecology and economy have been slow to engage retrofitting, an absence that is conspicuous as these fields take on planetary repair as a conceptual provocation and turn in mainstream conservation. this paper explores us retrofitting as a distinctive material repair practice, one born as an energy poverty program amid the scarcity fears of the s energy crisis but seeing a renaissance today as a program for green capitalist growth. i interrogate two economies of repair now emerging around retrofitting, energy market and cleantech aspirations to make energy efficiency a resource and articulated efforts to sell retrofits as new green value for real estate development and investment. such urban revaluation efforts join an expanding array of green gentrification schemes today. 	 	 paradoxically, even as would-be green entrepreneurs are drawn to these seemingly intangible and “clean” forms of waste and value-in-waiting, retrofitting presents intransigent materialities. its decarbonization ambitions demand not just profit-generating urban repair today but large-scale urban maintenance into the future. this need confronts longstanding efforts to render us cities and built environments flexible to recurrent creative destruction in service of ongoing economic growth. such logics of de/revaluation and essential disposability permit concurrent us programs for gentrification and urban abandonment today. however, decarbonization requires a more substantial confrontation with capitalist ruination-as-usual. in the s, climate change became an urban problem in a new way. in the united states, major cities announced sweeping projects of urban retrofitting in the name of energy conservation and decarbonization. initiatives such as new york city’s planyc, los angeles’ sustainable plan, and chicago’s retrofit chicago promised to repair and modernize broad swathes of their existing built environments for improved energy efficiency, substantially reduce citywide energy use, and slash greenhouse gas emissions. meanwhile, state legislation such as california’s assembly bill and senate bill targeted existing buildings in and beyond cities, in california’s case ambitiously committing the state to double its energy efficiency by . together, such energy retrofitting programs in the united states, alongside similar efforts in europe and other older industrial economies, are shaping an important problem space, and space of imagined solutions, for climate response. namely, in taking on such places’ existing built environments and energy practices, they prioritize these second natures “at home” – problem-location that has often eluded a global carbon economy of emissions trading, offsetting, and other geographical displacements to rural and exploitable spaces. moreover, they diverge from the green master planning visions of new eco-cities. retrofitting takes on capitalist ruin/s more directly and intimately. centrally, it 	 	 confronts an increasingly obtrusive legacy of th century industrialism: that its built environments, constructed with the assumption of cheap and abundant fossil energy, chronically bleed energy and emissions when they fall into disrepair. political ecology has been slow to engage climate retrofitting as a movement and practice (edwards and bulkeley , knuth ), even as retrofitting provokes new critical analysis amid broader debates on anthropocene urbanism and resilience (e.g., hodson and marvin , hodson et al. , cohen , bouzarovski et al. , and see derickson , long and rice ). this absence is conspicuous as political ecologists take on planetary repair more expansively, as a conceptual provocation for an era of global environmental destabilization and as a conflictual turn in mainstream conservation practice – particularly as technofuturist visions of ecological design and geoengineering gain new adherents (e.g., latour , robbins and moore , collard et al. , tsing , mansfield and doyle ). despite urban political ecology’s longstanding commitment to “renaturalizing” cities, urban second natures have often been sidelined in debates on repair’s political future. moreover, urban buildings and interior environments have been marginal concerns for a subfield preoccupied with more visibly “green” urban ecologies and networked infrastructures (although see day biehler and simon , knuth , cohen , wachsmuth and angelo ). in this paper, i make a new intervention in these discussions. first, i explore energy (/decarbonization) retrofitting as a distinctive practice of material repair. its sociomaterial assemblages remain geographically particular in important ways, shaped by divergent regional histories of urbanization, energy- technological modernization, disinvestment, and degradation – as well as meaningful climatological and vernacular architectural difference. therefore, i ground this paper’s survey in 	 	 a specific us experience of energy retrofitting, one born in the complex political moment of the s energy crisis. this period’s brief but influential brush with energy scarcity and conservation thinking inflected welfare programs such as weatherization (in an often-buried history of energy poverty in the united states), countercultural imaginaries of alternative energy futures, and urban redevelopment and rehabilitation struggles – all significant in retrofitting’s evolving politics, then and now. more centrally, i consider what retrofitting is becoming. like other prominent programs of environmental repair and restoration/redesign today, energy retrofitting is being positioned in today’s us initiatives as at once a decarbonization strategy, frontier for green innovation and entrepreneurialism, and prop to capitalist accumulation-as-usual. political ecologists increasingly critique repair and restoration’s place in such green growth visions (e.g., goldstein , mansfield and doyle ). fairhead et al. ( ) persuasively argue that “the damage inflicted by economic growth generating unsustainable resource thus creates the basis for the new growth economy of repair” in which “unsustainable use ‘here’ can be repaired by sustainable practices ‘there’, with one nature subordinated to the other” (p. ). they argue that this interplay results in “doubly valuing nature: for its use and for its repair…in such a way as to maximise both economies – of growth and of repair – with the intent of getting the very most out of nature and with maximum efficiency” (p. ). if retrofitting brings fairhead et al.’s “economy of repair” home in noteworthy ways, it simultaneously reignites longstanding questions about energy efficiency’s ability to achieve energy conservation. like fairhead et al., skeptics have long argued that such interventions may trim energy “waste” while accommodating – and even promoting – growing energy use. political ecology, with often-allied degrowth advocacy 	 	 (d’alisa et al. ), must therefore explore whether energy retrofitting offers more durable decarbonization possibilities despite today’s green growth aspirations – and, if so, with what obstacles and delimitations. in this paper, i therefore examine two particular economies of repair now emerging around energy retrofitting in the united states. i survey material visions, value propositions, and valuation efforts in these developing green sectors – thereby advancing new insights into value in green capitalism, a theoretical project now spanning political ecology, political economy, and cultural economy (e.g., kenney-lazar and kay , knuth ). first, i explore how retrofitting has been taken up by a wave of energy efficiency entrepreneurs, furthering market- led transformation and turbulence in the us electric power system. new accumulation visions propose “energy efficiency as a resource”, value that can be profitably cultivated or mined within existing buildings (and see knuth ). such aspirations have drawn both major corporate players and “cleantech” start-ups to the sector. together, they are shaping an important frontier within the green economy’s broader waste to resource program (gregson et al. , , knapp ) – one with a distinctive (im)material bent. second, i draw on urban political economy to consider the property sector that shapes these built environments, and the prospects for realizing many such green capitalist hopes. a parallel accumulation project is now developing among real estate developers, investors, would-be green financial innovators, and entrepreneurial urban governments. these players are working to translate energy retrofitting and value-added into an instrument for real estate conversion, revaluation, and speculation; for example, in drives to appraise and certify a green value premium for retrofitted properties, and to enlist future energy savings as a new revenue stream for financing building adaptive reuse. these 	 	 revaluation efforts join an expanding set of green gentrification schemes today, a growing concern of urban political ecology and economy. meanwhile, historic preservation players and other institutions with a stake in the united states’ legacy built environments are generating new energy and emissions data to sell retrofitting – an exercise with unexpected radical potential. with this first-cut survey, i draw out a central paradox of retrofitting initiatives’ vision for decarbonization and/as green growth. would-be green entrepreneurs have been drawn by the intangible form of urban-industrial waste, energy and emissions inefficiency, that retrofitting projects target as value- and resource-in-waiting: significantly, an attractively “clean” and malleable one compared to the frequently intractable, abject, and risky materialities of industrial byproducts, urban discards, and contaminated brownfield land (gregson et al. , , gidwani and reddy , dillon ). meanwhile, it offers us cleantech players enticing opportunities for light-footprint business models in green services, information technology, and financing – an important departure from the material- and capital-intensive manufacturing that frustrated the sector in the late s (knuth ). more fundamentally, it suggests an important accumulation frontier for economic decoupling, ecological modernization’s central proposition that an innovative capitalism can detach growth from its energy and material metabolisms. this proposal requires (again, necessary but far from sufficient) the successful production of such intangible value forms, assets, and economic spaces. indeed, i suggest that early us countercultural experiments with energy efficiency helped make green growth imaginable. however, i argue that in practice, retrofitting initiatives confront fairhead et al.’s critique in a particularly wicked form. in their ineluctable material dependence upon urban built environments and capitalist urban interests, they enter a space hostile to their deeper 	 	 decarbonization goals – and possibly even the more delimited aspirations of their green capitalist adherents. as a decarbonization strategy, retrofitting requires not just potentially profitable urban repair today but large-scale urban maintenance into the future – a far more demanding challenge to capitalist ruination. retrofitting’s roots: weatherization and the specter of energy scarcity the energy crisis of the s was a generative moment in us politics, in ways immediately apparent and in ways only being realized or remembered today. in recent work, huber ( ) has tracked the influence of this jarring encounter with energy scarcity in the crisis of us keynesianism, the rise of neoliberalism, and the birth of a new era of us oil adventurism and imperialism abroad. domestically, the energy crisis influenced a broad set of contemporary debates, in ways farther-reaching than new questions about oil abundance and automobility. as i will discuss below, concerns for energy waste and conservation inflected the era’s politics in spheres as diverse as electric utility politics, urban redevelopment protests, and the rise of historic preservation. however, the energy crisis’s arguably most direct influence on the development of energy retrofitting was in the birth of the us weatherization assistance program in (and see harrison and popke ). in low-income weatherization, ultimately funded through both the department of energy (doe) and the department of health and human services (dhhs), the federal government has for decades paid for home energy efficiency audits and repairs for improved energy performance, with eligibility requirements that target low- income households – who, even in the energy-rich united states, continue to spend a disproportionate amount of their income on basic energy uses (berry et al. ). the energy 	 	 crisis provided a crucial spark for weatherization efforts, as spikes in the costs of home heating oil compounded existing consumer strains like stagflation. however, the program speaks to more fundamental tensions in the spaces of high-energy capitalism. crucially, weatherization programs problematized, if tacitly, the built environments and embedded energy practices of previous generations: the united states’ variety of industrial capitalism was in crucial ways generated through dedicated campaigns for urban redevelopment and building energy-technological modernization. electric utilities, manufacturing corporations, and interested policymakers sought deliberately to promote unprecedented levels of energy consumption society-wide, and ways of everyday life organized around it (nye , hirsh ). this mission required a broader revolution in building design, in programs initiated in the s and expanded through the new deal-keynesian era – for example, the public-private campaign to produce the suburban “minimum home” and its electric appliance suite (hise ). moreover, it required a large-scale program for energy retrofitting, parallel public-private drives to modernize existing built environments for the new high(er)-energy capitalism – for example, new deal programs to rewire older homes for full electrification (tobey ). such built environments now subsume high levels of energy use within taken-for-granted practices, obdurate materialities (hommels ), and normalized assumptions – a process of rendering- inconspicuous that shapes energy consumption in stubborn ways (walker and large , shove ). particularly challenging to energy conservation efforts, the spread of central heating and then air conditioning created rising expectations of atmospheric control and comfort within a vast and growing interior environment. this second nature now spans diverse climatic regions across the united states, and has spawned an array of building designs and settlement 	 	 geographies marginally habitable without high energy consumption (although many energy-poor people are nonetheless required to do so). resultant heating and cooling loads now dominate energy use in us buildings, particularly housing (doe ). omnipresent but for many invisible or involuntary, such materialities present broader challenges to campaigns for energy conservation and decarbonization. weatherization confronted such high-energy spaces and geographies as a problem in a novel way – a source of vulnerability should energy subsequently become scarce or unaffordable. in response, the program pioneered practices of repair that continue to characterize many energy retrofitting initiatives. notably, it centrally problematizes how buildings can waste energy. this focus does not wholly capture the many ways in which people or economic sectors may metabolize high-quality energy, “wastefully” or not (for example, through the introduction of new energy-using devices and their infrastructures). however, it turns a practical lens on buildings’ vital materialities and sociomaterial assemblages (bennett , mcfarlane , and see gieryn , graham and thrift ). like all earth surface structures, buildings materially break down over time due to weathering and entropic processes, including biological ones (day biehler and simon ) – dissolution that requires ongoing human maintenance interventions to slow and reverse. meanwhile, products of a sociotechnically volatile capitalism, buildings frequently crystallize designs, technologies, and construction techniques that subsequent innovations render obsolescent – suboptimally efficient to operate in energy terms, as well as merely unfashionable (and see weber , abramson ). degradation of building shells due to weathering and undermaintenace renders their interior natures permeable to surrounding environmental fluxes, leaking warm air out (or hot air and moisture in), 	 	 compromising inhabitants’ comfort and health, and demanding ever-increasing amounts of energy to effectively heat or cool. meanwhile, physical plant technologies such as heating systems and boilers wear out over time or are technologically superseded. weatherization, like energy retrofitting more generally today, has thus sought to reduce building energy waste through a combination of repair (locating and patching leaks, fixing building elements like outside doors and windows) and technological modernization (replacing appliances like electric lights and refrigerators and larger physical plant elements like heating systems, updating building shell technologies such as improved wall or attic insulation, and so forth). more immediately, weatherization efforts have been an acknowledgement, albeit fleeting and quickly marginalized, that energy scarcity remains a reality for many in the united states via unaffordability. a recurring theme in this persistent energy poverty is unequal exposure to disrepair and obsolescence in habitation and other everyday built spaces (harrison and popke ). this inequality takes multifarious forms in the united states (within a broader global geography, e.g., silver ). the poor often inherit older, undermaintained buildings. paradoxically, this process is lionized in longstanding mainstream discourses of “filtering”, housing affordability via trickle-down (critiqued in slater ). alternatively, they may rely on habitation not built to last (see harrison and popke on the problems of weatherizing us mobile homes) or, as renters, endure landlords’ causal or strategic building neglect (smith ). moreover, notwithstanding important histories of sweat equity in building and neighborhood rehabilitation (e.g., kinder ) such households also have unequal access to the means of repair, including through legacies of racialized redlining and broader financial exclusion. in important ways, therefore, federal weatherization has operated both as an energy conservation 	 	 program (the primary remit of its doe funders) and a form of government economic redistribution (dhhs’s priority, alongside direct energy bill aid and other social welfare programs). however, such redistributive power has been chronically limited in practice. moving out of the energy crisis, fossil fuel interests and us society writ large clamored for a return to high energy growth, rejecting calls for broad-based energy conservation. meanwhile, a rising neoliberalism began to pick off and undermine keynesian welfare programs. low-income weatherization, objectionable on both counts and dependent upon congressional appropriations, has suffered chronically limited resources for decades – and, periodically, the threat of complete defunding (berry et al. , tonn et al. ). despite its resource restrictions, low-income weatherization has been a noteworthy example of long-term energy conservation policy – and, as such, raises important questions. governmental assessments of the program argue that it achieves substantial energy savings for its participants (e.g., tobey et al. ). these assessments provide important support for retrofitting’s energy conservation potential (if not a final word, as such claims face ongoing questioning and speak in any case to a subset of retrofitting’s potential clients). critics often invoke a longer-term debate around energy efficiency, the problem of the “jevons paradox” (or a “rebound effect”). derived from william stanley jevons’ observations on coal-mining in the early industrial revolution, this economic model suggests that as efficiency improvements cheapen energy use, they simply encourage more energy use – prompting energy efficiency and consumption to grow together. this possibility presented scant challenge to earlier us energy efficiency advocacy, as taylorists and technocrats in the progressive era actively pursued efficiency-led industrial growth – a durable waste-trimming logic in industrial ecology. however, it is a central concern for eco- 	 	 efficiency hopes today, for both decarbonization and green capitalism (as seen in fairhead et al.’s related critique). nonetheless, in retrofitting’s case, the jevons paradox is a simplistic gloss on complex sociomaterial relations. it is by no means obvious that recipients will pour energy cost savings from repair projects back into intensified energy usage – or even into broader consumer spending, although weatherization programs may invoke such keynesian growth benefits. as energy retrofitting programs multiply and become more expansive, these questions demand ongoing scrutiny. retrofitting for green growth: emerging economies of repair writing during the energy crisis, walker and large ( ) outlined a more serious problem of energy conservation: that given us structural dependence (including through its built environments) on high energy consumption and/for ongoing economic growth, its proposition was rather more radical than advocates perhaps appreciated. framed in a language of scarcity, conservation might be (barely) tolerated as a marginal program for the poor, but faced fierce resistance as a large-scale social undertaking. unsurprisingly, therefore, today’s renaissance in energy retrofitting has been accompanied and enabled by a profound shift in how it is imagined: instead of project of scarcity, it is now being framed as an opportunity for economic growth. the new retrofitting in many ways embodies a central proposition of market environmentalism: to use novel (re)valuation schemes and markets to turn problems like the us’s high energy and emissions footprint on their heads, framing them instead as untapped resource frontiers. in the process, retrofitting’s public and private advocates are targeting new populations, built 	 	 environments, and sectors as accumulation opportunities. i consider two such emerging economies here. energy efficiency as a resource: retrofitting and energy market transformation first, one key proposition driving new private sector interest in retrofitting comes from a growing array of schemes to reframe energy efficiency as a resource – a key frontier in broader market-led transformation within the us electric power system. like weatherization, these energy market schemes have deeper roots in the s energy crisis. as the period’s rising prices and scarcity fears shook us high-energy assumptions, they further destabilized a national energy paradigm already experiencing challenges from within and without: the us electric utility system, and particularly its modernist “grow and build” model. for decades, investor-owned utilities commanding state-granted “natural monopolies” had captured increasing economies of scale from ongoing expansions in their customer base and electric services consumed, load balancing across the power grid, and rising thermodynamic efficiencies within increasingly large generation plants (hirsh ). by the s, the material and political bases of this growth were breaking down. amid environmentalist challenges and rising interest in alternative energy, technologists and activist energy regulators began to experiment with new ways to encode energy efficiency and conservation into utility sector business models. national labs investigated designs for high-efficiency lightbulbs and other consumer appliances, while progressive state public utility commissions pushed for “demand side management” (dsm) and related customer conservation programs, including a broad set of retrofitting practices. 	 	 utility programs like dsm suggested radically novel logics of commodity valuation and accumulation, ones that spoke to emerging green countercultural thinking in the late s and s. specifically, dsm proposed to depart from previous industrial ecological models by monetizing not only efficiency but net energy conservation – defined not on open markets but in an institutional structure of price approvals through public utility commissions. the new programs represented utility spending on efficiency programs and other load management efforts as formally equivalent to new energy generated from power plant construction. in other words, it became possible to imagine energy efficiency as a thing, and a potentially valuable thing, in a new way: simply another resource in utilities’ portfolios, if in a novel intangible form. such unconventional and alternative energy ideas were supported by broader countercultural experimentation in centers like the san francisco bay area, advanced through utopian social projects, regional policy development, and movement publications such as stewart brand’s whole earth catalog (kirk ). significantly, through such projects the green counterculture pioneered a new technofuturist turn in us environmental thought – one powerfully shaping cleantech and green economic imaginaries today. influential alternative energy advocates in this countercultural milieu included figures like brand and amory lovins. for example, in the sphere of energy conservation and its nascent value experiments, lovins proffered the notion of “negawatts” to sell efficiency interventions’ ability to produce an intangible but real, quantifiable, and potentially valuable product (hirsh ). such early visions not only anticipated market environmentalism’s raft of similarly intangible environmental commodities like tradable carbon credits and ecosystem services (fairhead et al. ), but also deeper post- industrial logics behind ecological modernization and green growth – possibilities for expansive spheres of intangible value and, ultimately, economic decoupling. 	 	 in the contemporary moment, this revolution in valuing efficiency has arguably been most important for utilities’ competitors, a rising tide of capitalist entrepreneurs who have sought to overturn th century utility monopolies. these mounting transformations in the us electricity sector have been supported by a wave of deregulation since the s (accompanied by a wave of similar neoliberal restructuring abroad under structural adjustment programs). one important justification for market restructuring was to create new opportunities for a specific type of competitor, non-utility energy efficiency businesses. for example, in the s new energy service companies (escos), dramatically expanding a model also originally experimented with in the s energy crisis, proposed to join or fully replace utilities as providers of efficiency retrofits and other functions. escos specifically targeted large public and institutional buildings and campuses, complex built environments that presented repair and modernization possibilities beyond weatherization’s scope - building commissioning, retrofits, project financing, and other services. escos’ proposed profits typically have come from energy performance contracting, a specific framing of energy efficiency as a resource: they are paid out of energy costs that they succeed in saving clients. in addition, escos also often market in-house or third party financing packages to cover the upfront costs of retrofits. they advertise that once these upfront costs and fees are recouped through subsequent reductions in energy and energy costs, building owners and operators will be left with years of their own valuable savings. the california energy crisis and enron scandal, spurred by opportunistic speculation around the state’s electricity deregulation, soured the us esco market for years – not least because enron’s energy services had helped lead this initial wave. many private escos failed or consolidated, and utilities shuttered versions started in-house. however, escos again became big us business with the 	 	 rise of the green economy in the late s, with a new wave of growth and major expansion into sectors like commercial real estate. leading escos in the us today include massive multi- national corporations such as siemens, johnson controls, honeywell, and schneider electric, in a growing global market – $ billion in , and projected to double to $ . billion by (navigant research ). in addition, silicon valley experiments with cleantech since late s have generated a wave of energy efficiency start-ups, companies that now seek to seize market share from both utilities and larger escos and “disrupt” their established business models. high-profile startups today such as opower and drift have targeted new energy efficiency markets in and beyond retrofitting, developing business models around new sectoral trends such as digitization, big data applications, device-centered behavioral energy efficiency, and demand-side “behind-the-meter” energy storage (a strategy to support the power grid management challenges of another expanding frontier of green capitalism, rapid renewable energy deployment) (e.g., levenda et al. , knuth ). meanwhile, a related set of green investment entrepreneurs such as renew financial and ygrene have targeted the sphere of finance for retrofitting, especially for new private commercial and residential sector markets. such companies now advertise a raft of experimental instruments such as property assessed clean energy (pace) financing to cover clients’ upfront retrofitting costs, often alongside secondary market construction practices such as loan bundling, on-selling, and asset-backed securitization (familiar property financing practices pre- and post-dating the subprime bubble). together, such energy efficiency services and financing start-ups exemplify a broader silicon valley strategy for pushing its comparative advantage in a globally competitive green economy – one that disappointed aspiring us 	 	 cleantech manufacturers in the late s (knuth ). these “cleantech . ” entrepreneurs have instead looked to software, services, and other material- and capital-light business models – ones seemingly ideally placed to produce intangible assets like energy efficiency as a resource. these energy efficiency as a resource schemes join a broader waste to resource project in the green economy. novel efforts to revalue urban and industrial waste streams are building on longer-term industrial ecological projects to eliminate energy and resource inefficiencies, as well as more diverse legacies and geographies of industrial and municipal waste salvage. like energy retrofitting, these efforts have recently brought capitalist repair home to industrial capitalist economies – for example, in new programs to recover industrial waste streams for mining and reprocessing. without the geographically fixed object that retrofitting possesses in urban built environments, some of this (re)location has been a product of deliberate social and environmental policy (gregson et al. , knapp ). such projects are a growing concern within political ecology (including via its new interest in industrial ecology; newell and cousins , huber ). critically, as gregson et al. ( , ) argue, these waste streams’ intransigent materialities present major challenges to reframing them as “clean”, innovative accumulation frontiers. all too often, waste remains stubborn, dirty, and dangerous – particularly to those who labor to process it, and the spaces that house such transformations (and see gidwani and reddy , dillon ). as a form of waste and nascent resource, energy inefficiency presents a radically different and attractive (im)material profile for management and revaluation. indeed, mulvaney ( ) warns that this relative cleanliness can make energy and greenhouse gas emissions waste a problematic entry within industrial ecological practices like life-cycle 	 	 analysis, as corporations seize upon profitable eco-efficiency opportunities while obscuring more difficult and toxic industrial byproducts. the search for a green premium: retrofitting and green gentrification critically, however, retrofitting projects are not creatures of energy markets alone, nor are they nearly as free to shed their material bases as some new sectors suggest. rather, they depend in inextricable ways upon the materialities of existing urban fabrics and everyday practices, as well as upon cooperation from the entrenched assemblages of real estate development and valuation that shape these environments. how, therefore, do new projects to monetize and mine energy efficiency in buildings materialize on the ground, particularly within urban property markets? significantly, as energy efficiency as a resource ideas have expanded today, an articulated set of practices is now emerging within spaces of real estate (re)development, public and private. once again, earlier encounters with energy scarcity have been generative in this activity. low- income weatherization was not the only initiative for built environment repair developing in the united states through the s, nor was it the only effort to articulate the energy and environmental significance of its practice. environmentalist concerns joined a broader rising critique of modernist city-building, particularly the excesses of midcentury downtown redevelopment and urban renewal – rapid architectural obsolescence, large-scale demolitions and displacements, and the destruction of significant historical landmarks; atop farther-reaching processes of disinvestment and abandonment in older industrial cities (harvey , zukin , cairns and jacobs , abramson ). movements for building rehabilitation, adaptive reuse, and historic preservation, collectively protesting the wastefulness of this ruination, 	 	 advanced alternative visions of urban salvage and maintenance – demands for fixity that paralleled the era’s broader environmental conservationist programs, and often with similar nostalgia and settler colonial elitism (e.g., in historic preservation’s call to protect culturally “significant” and “original” buildings and neighborhoods; zukin , and see collard et al. ). amidst the energy crisis, these conversations advanced noteworthy – if, again, all too brief – critiques of the more particular energy wastefulness of rapid urban obsolescence and redevelopment (smith , national trust for historic preservation ). it bears remembering here that this turn to fine-grained urban repair and rehabilitation, within both grassroots activity and government redevelopment policy, classically defined gentrification as a practice – even as the term and practice subsequently expanded to encompass more diverse interventions like new-build redevelopment (e.g., glass , smith , davidson and lees ). however, as gentrification entered the mainstream, its early energy concerns quickly fell out and were forgotten. some of these energy and environmental roots were translated into later campaigns for green design in new construction – for example, through the development of the us green building council’s (usgbc) leadership in energy and environmental design (leed) standard and rise of new urbanist planning (abramson ). recently, these foundational concerns have been more explicitly excavated and resuscitated within historic preservation, as a new campaign to “green” preservation seeks to rearticulate and reconcile its project with large-scale energy retrofitting and decarbonization (national trust for historic preservation ). notably, the national historic trust’s new preservation green lab ( ) has developed a dedicated program of data-gathering to support energy retrofitting. 	 	 the current moment is seeing a broader uptake of energy retrofitting within mainstream real estate development, in explicit green capitalist terms. significantly, a wave of major commercial real estate developers and investors retrofitted their property portfolios in the late s and s, voluntarily and via participation in new public-private decarbonization initiatives. this activity was aided by escos’ concurrent expansion into the private commercial property sector and the development of dedicated real estate certification and investment tools. for example, the usgbc developed a new label for retrofitting projects, the leed for existing buildings: operations and management (ebom) standard, a private certification that joins existing federal labels like energy star. knuth ( ) provides a window into the interplay – and frictions – between energy efficiency and more expansively defined “green” retrofitting and labeling in such projects. in , in the early years of the leed ebom standard, the usgbc reported approximately . million square feet certified nationally, a figure dwarfed by traditional new green building certifications ( . million square feet). by , annual ebom certifications surged to . million square feet and remained in the hundreds of millions throughout the early s, surpassing new building certifications every year (green buildings information gateway ). meanwhile, the urban and state level energy retrofitting policies described above worked to promote and support this wave, via large-scale retrofitting targets and the codevelopment of other tools such as retrofitting financing apparatuses – including via partnerships with new green financial institutions. many such programs also sought to expand private retrofitting in housing – so far more challenging than the commercial property sector (in this vein, see also federal programs like the obama administration’s better building challenge and stimulus-era funding spikes for low-income weatherization, accompanied by new efforts to reframe weatherization for/as green economic development; tonn et al. , edwards and bulkeley ). 	 	 these new economies of repair require dedicated programs of green valuation and market construction, in and beyond the us urban context. such initiatives join now-extensive public- private campaigns to “green” (or re-green) gentrification more broadly defined, processes that urban political ecologists and economists are tracking in multiple forms (and see anguelovski ). significantly, many such efforts are advancing new relationships with urban (dis)repair and forms of property revaluation that may be attached to it. for example, they encompass an expansive encounter with the unruly ecologies and disorder of urban wastes and abandoned infrastructures, one now animating high-profile projects of aesthetic reappraisal, post-industrial park development, and real estate speculation (e.g., gandy , millington ). they also include programs of brownfield remediation and urban clean-up – longstanding grassroots efforts now appropriated by high-value property redevelopment (checker , dillon ). scholars of green gentrification are increasingly interrogating more precisely how these various forms of greening may raise urban property rents and exchange values, and how developers may appraise and appropriate this speculative premium (bryson , anguelovski ). such novel revaluation strategies are joining longer-term efforts to find and exploit urban rent gaps and land revaluation potential (e.g., smith , weber , slater ). green gentrification projects might raise rents around new green amenities, mitigate rent impairments on and around dilapidated and contaminated brownfield sites, or both. as dillon ( ) proposes, such revaluation exercises may transmute abject urban wastelands into wastelands in a classic lockean sense: invitations to capitalist intensification and, through this “improvement”, private appropriation of resulting value. however, energy retrofitting’s entry into these repair 	 	 and revaluation frontiers is only beginning to be interrogated (although see knuth , bouzarovski et al. ). i suggest that energy retrofitting adds both new value streams and tools to projects for gentrification and adaptive reuse. drawing on today’s growing pool of buildings retrofitted and certified under standards like leed ebom and energy star, real estate data analysts have given this trend fresh fuel by declaring that certified green and energy efficient buildings have become demonstrably more valuable than their non-green competitors (calculations once again particularly established for commercial real estate, although advocates make similar claims for high energy performance homes) (rydin ). this “green premium” reflects multiple valuation logics (as knuth also argues). notably, like past shifts around modernization and property obsolescence, it is in part a creature of collective market perception and fashion (and see weber , abramson ). green real estate is quite capable of becoming more valuable simply because enough developers and investors are convinced that it is (for now). conversely, property owners may legitimately fear that failing to jump on a greening bandwagon risks properties’ future desirability to prospective tenants and investors, prompting downgrades from “class a” investment status, diminished ability to attract tenants and command competitive rents, and, ultimately, devaluation. at the same time, energy cost savings generated through retrofitting projects suggest a calculable stream of value to capitalize into broader property exchange values and rents – a potentially less vulnerable locus of revaluation, given the capriciousness of urban real estate markets and ongoing ambiguities in precisely what use and exchange values a green premium expresses (for example, green building labels remain vague and problematic as a proxy for energy conservation and decarbonization potential, e.g., knuth 	 	 ). broader energy market developments might increase this value-added. a return to high energy prices, effected through new scarcities or pricing greenhouse gas emissions, would increase the cost of energy waste and the value of efficient spaces. more recently, commercial property developers have begun to consider energy value-added as a new revenue source to fund and finance rehabilitation and adaptive reuse projects. they are adding streams of anticipated future value from retrofits, especially financed upfront via instruments like commercial pace, to already densely stacked value streams – from historic tax credits, transferrable air and development rights, low-income housing tax credits (for below market-rate rental housing units), and beyond. these revaluation campaigns depend upon equally dedicated efforts to render energy improvements visible in property records and appraisal apparatuses – articulated with parallel efforts to map energy problem spaces and devalue inefficient properties as impaired. such initiatives have been another important project of public retrofitting programs today. for example, cities such as san francisco, seattle, austin, and washington, d.c. launched large- scale energy benchmarking efforts in the s and s, policies designed to officially record and track buildings’ energy performance. california’s ab established a similar benchmarking rule for commercial buildings and multifamily housing statewide. meanwhile, in a different data-gathering register, entities like preservation green lab are now highlighting other key logics for retrofitting. using tools like life-cycle analysis, this institution is developing new pictures of both the energy required to operate buildings in various us regions (of various historical vintages) and the “embodied” energy required to build, demolish, and rebuild them (preservation growth lab ). these calculations present a significant case for retrofitting and 	 	 maintaining existing built environments, instead of removing and replacing them with new high- efficiency designs. they argue that older us buildings – especially those built before midcentury pushes for high-energy modernization and manufactured obsolescence – are unexpectedly energy efficient if maintained. this argument represents an important departure from conventional wisdom in the us context (national trust for historic preservation ). furthermore, this analysis maintains that new high energy performance buildings might take decades of operational efficiencies to recoup energy and emissions released in their construction. these findings raise a profound question: are today’s new retrofitting initiatives prepared to turn more durably to urban maintenance? conclusion: decarbonization in a restless urban world what does the first-cut survey presented here suggest about energy retrofitting as an urban repair program, and its possibilities for energy conservation and decarbonization? within unfolding debates over planetary repair and its global economy, retrofitting is an exceptional project in significant ways. as it moves such practices and economies home to urban and capitalist centers, it presents more meaningful opportunities for reforming these spaces and their dynamics. this paper’s discussion suggests that political ecology should take retrofitting seriously as a practice of repair, one with decarbonization outcomes that might outlive backers’ current green growth aspirations. this is true despite legitimate concerns that energy efficiency campaigns (even successful ones) may not check net growth in energy consumption and greenhouse gas emissions. significantly, in targeting existing built environments for its intervention, retrofitting addresses crucial shaping factors in energy use and emissions, in the us context and beyond. 	 	 these inconspicuous yet vital materialities are insufficiently considered in many degrowth proposals today (e.g., d’alisa et al. ): embedded energy use practices such as space heating and cooling may powerfully resist programs of voluntary simplicity for the comfortable, as well as austerity, energy scarcity, and involuntary simplicity for the energy-poor. if retrofitting illuminates more durable possibilities as a practice of repair, its economies of repair remain far murkier. this paper has explored multiple would-be accumulation frontiers helping drive us energy retrofitting today, all of which remain works in progress. in this first-cut survey, it is certainly possible to read would-be green capitalism as an enabling force for large-scale retrofitting in the united states – its expansionary growth rhetoric and technofuturist visions have helped the practice go mainstream in ways that invocations of scarcity and wastefulness in the energy crisis failed to do. ways in which retrofitting, energy conservation, decarbonization, and accumulation might run together in the near term thus represent an unusually open question. in exploring some fine-grained responses to it in the value and market infrastructures surveyed here, this discussion suggests important takeaways and, unsurprisingly, further questions for political ecological and economic research. notably, many value propositions now emerging here, whether around energy efficiency as a resource or green real estate revaluation, do seemingly depend upon translating retrofits into demonstrable energy conservation. however, how durable such energy savings must and will be is less clear. new green entrepreneurs might succeed in collecting the more immediate fees and cuts discussed, but what about the clients charged with maintenance of these building improvements over the long term? green accumulation and growth schemes might successfully gloss over such questions, as they expand into built environments across the united states and frontiers beyond – indeed, non-durability 	 	 might simply present them new opportunities for fresh repair contracts and profits down the road. however, governmental decarbonization programs must take a more holistic and long-term view of these questions, as must critical evaluations. ultimately, the more pertinent dilemma here may not be the durability of energy savings from retrofitting as a practice – potential rebound effects and growth-enabling efficiencies notwithstanding. rather, it may lie in the intransigent materialities in and upon which retrofitting must work (in contradiction to the immaterial visions of some proponents): the durability of the buildings its initiatives target. as the discussion above begins to suggest, decarbonization imperatives encounter serious challenges in capitalist urbanization: its geographical “restlessness” (harvey ), and how such an imperative encodes material obsolescence into its built environments and assemblages. to justify their new political placement and broader revaluation, retrofitted buildings must not only be repaired but maintained and conserved into the future. if not, they will sacrifice not only their new emissions-averted but shed additional energy and emissions in their degradation, demolition, and disposal – significantly, echoing a problem encountered in forest carbon offsetting and other geographies of planetary repair. in urban contexts, this fixation may require sacrificing the prospect of higher returns from future building conversion or destruction. as such, it contradicts a longstanding imperative of (and tension within) capitalist urbanization, one with a long legacy in us land and property infrastructures (e.g., plotkin ): that cities and built environments should be rendered flexible to recurrent creative destruction in service of ongoing economic growth. 	 	 expanding apparatuses of gentrification in the us “return to the city” have arguably proffered a distinct urban version of fairhead et al.’s ( ) problematic economy of repair. on the one hand, developers exploit a growing array of tools for building rehabilitation, revaluation, and adaptive reuse, including the new energy and environmental ones surveyed here. these infrastructures join more longstanding ones – even at the height of the united states’ more unabashed mid- th century enthusiasm for urban obsolescence and redevelopment, some urban landscapes were maintained by and for their inhabitants (smith ). while capitalism may in theory treat all land as a financial asset and all structures upon it as therefore disposable in pursuit of an ever-evolving “highest and best use”, such a project has been more partial and contingent in actual practice (harvey , christophers , knuth ) – and, moreover, encounters unruly materialities like brownfield contamination in challenging, undertheorized ways (dillon ). collectively, these activities are expanding an important program of repair in us urbanism, as well as new strategies to profit from it – albeit at the cost of persistent racialized and classed displacement. on the other hand, urban governments and developers have continued to elaborate upon a vast array of tools for urban redevelopment and land speculation – for writing down the value of existing buildings, foreshortening their material lifetimes, and otherwise facilitating their profitable removal and replacement (weber ). more broadly, us capitalism and urbanism remain bound in conjoined geographies of regional boom and bust, growth and decline, and speculation and disinvestment – accompanied today by fresh programs of demolition within shrinking 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zukin s ( ) loft living: culture and capital in urban change. new brunswick, nj: rutgers university press. with variable promises, timelines, and metrics (e.g., per building, square foot, or across a whole building stock). including exploitable spaces close to home, as protested in environmental/climate justice activism. particularly in the energy/decarbonization realm i consider here. despite metaphorical allusions to urban “gardens”, and an expansive debate on planetary urbanization, a concept that occludes many of the distinctive urban materialities discussed here. 																																																								 	 	 																																																																																																																																																																																			 although see its explorations of disrepair in urban infrastructures in the global south, including for electricity (e.g., mcfarlane , silver ). see also kinder ( ) on diy repair practices in detroit neighborhoods. this discussion builds on fieldwork originally conducted on us retrofitting in - , with recurrent follow-ups thereafter. this work has included participant observation in governmental forums and industry conferences nationally (for example, of the american council for an energy efficient economy); close reading of policies, industry publications and conference transcripts, and institutional position papers; as well as ongoing engagement with a wide-ranging technical and popular literature. across us regions, albeit with regional climatological variations. relations also explored by longstanding work in us cultural landscapes and vernacular architecture traditions. although increasing operational efficiencies are hardly a guarantee in the us context – other building trends like increasing single-family home size act as countervailing forces. ironically, in such breakdowns often enriching buildings as more-than-human ecologies (day biehler and simon ) – thereby hastening their structural dissolution. program funding was supplemented for years after the energy crisis by reparational levies on oil company profits. however, even at the peak of their allocations before the obama administration’s post- stimulus – during which they saw a major, if temporary, influx of funds – they only received $ million in total federal allocations. by the s, funding had declined to an average of $ - million annually (tonn et al., ). such chronically limited resources made for long program waiting lists and restrained program ambitions. and likely enabled such visions, though more fine-grained genealogical work is needed. lovins and brand have championed today’s market environmentalism and ecomodernism, while brand’s various engagements suggestively bridge the green counterculture, silicon valley tech, and building adaptive reuse (brand , turner , kirk ). one that created difficulties for utilities’ dsm experiments even as it opened up new opportunities for their competitors (hirsh ). as well as new independent players in renewable energy (hirsh ). these early clients often had broader social and environmental remits that encouraged participation before the solidification of escos’ value case (and see knuth ). as well as more profound industrial transformations beyond efficiency, opening up qualitatively novel technological and economic spaces, e.g., romero ). and remains subject to pressures to outsource waste to less protected spaces and laboring populations, or to import these inequities within domestic reprocessing (gregson et al. ). although large industrial artifacts like ships may be “building-like” in their complexity, buildings’ stubborn fixity in space and in relation to each other presents distinct geographical questions. for example, rahm emmanuel’s ambitious plans (mostly thwarted) to use his new infrastructure trust to finance hundreds of millions of dollars in chicago energy efficiency retrofits. similarly, renew financial, mentioned above, was originally developed out of the city of berkeley’s retrofitting financing experiments, including the birth of the pace model. as well as new forms of financialized extraction – see christophers ( ) on green infrastructure repair/replacement and experimental bond financing. particularly complex revaluation projects when urban land’s real estate “improvements” and impairments are retained or unsuccessfully rendered invisible – departures from the aspirational sweeping-clean of pure locational land revaluation. for example, in the city of san francisco required all existing large commercial buildings in the city to conduct yearly performance benchmarking and half-decadal comprehensive energy audits. similarly, citing green revaluation objectives, the city’s office of the assessor-recorder now enters buildings’ energy and environmental performance labels in its land records. such calls also critique how green labels like leed can value buildings’ component parts – fuel for waste to resource revaluation – over buildings as preserved structures. 	 	 																																																																																																																																																																																			 injustice which energy retrofitting may deepen in unanticipated ways – see, for example, its contributing role in london’s grenfell tower disaster.		 chchd connects mitochondrial metabolism to apoptosis | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . / . . corpus id: chchd connects mitochondrial metabolism to apoptosis @article{liu chchd cm, title={chchd connects mitochondrial metabolism to apoptosis}, author={y. liu and y. zhang}, journal={molecular & cellular oncology}, year={ }, volume={ } } 	y. liu, y. zhang 	published 	biology, medicine 	molecular & cellular oncology as the powerhouse of cells and gatekeeper for apoptosis, mitochondria control life and death. chchd , a mitochondrial protein previously known to regulate metabolism, has recently been identified as an apoptosis inhibitor. new data suggest a model in which chchd performs a prosurvival function by acting as both a reactive oxygen species scavenger and bcl-xl activator.  view on taylor & francis tandfonline.com save to library create alert cite launch research feed share this paper citationshighly influential citations background citations view all topics from this paper 	mitochondria 	chchd gene 	reactive oxygen species 	mitochondrial proteins citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency mitochondria in cancer 	debora grasso, luca x zampieri, tania capeloa, justine a. van de velde, p. sonveaux 	biology, medicine 	cell stress 	 	 	pdf save alert research feed chchd : the power house's potential prognostic factor for cancer? 	r. gundamaraju, wen-ying lu, r. manikam 	medicine 	frontiers in cell and developmental biology 	 	 	view excerpt, cites background save alert research feed mitochondria in cancer. 	g. gasparre, r. rossignol, p. sonveaux 	medicine, chemistry 	biochimica et biophysica acta. bioenergetics 	 	 	pdf save alert research feed erratum to: mitochondrial chchd-containing proteins: physiologic functions and link with neurodegenerative diseases 	zhi-dong zhou, wuan-ting saw, e. tan 	biology, medicine 	molecular neurobiology 	 	 	pdf save alert research feed a new mutation-independent approach to cancer therapy: inhibiting oncogenic ras and myc, by targeting mitochondrial biogenesis 	b. Ózsvári, f. sotgia, m. lisanti 	chemistry, medicine 	aging 	 	 	pdf 	view excerpt, cites background save alert research feed mitochondrial chchd-containing proteins: physiologic functions and link with neurodegenerative diseases 	zhi-dong zhou, wuan-ting saw, e. tan 	medicine 	molecular neurobiology 	 	 	highly influenced 	view excerpts, cites background save alert research feed identification of key pro-survival proteins in isolated colonic goblet cells of winnie, a murine model of spontaneous colitis. 	r. wilson, r. gundamaraju, + authors r. eri 	biology, medicine 	inflammatory bowel diseases 	 	 save alert research feed chchd promotes hepatocellular carcinoma and indicates poor prognosis of hepatocellular carcinoma patients 	yang yao, j. su, l. zhao, r. li, kaige liu, sheng-yu wang 	medicine 	journal of cancer 	 	 	pdf 	view excerpt, cites background save alert research feed varied pathological and therapeutic response effects associated with chchd mutant and risk variants 	m. tio, rujing wen, + authors e. tan 	biology, medicine 	human mutation 	 	 	view excerpt, cites background save alert research feed trem alzheimer’s variant r h causes similar transcriptional dysregulation to knockout, yet only subtle functional phenotypes in human ipsc-derived macrophages 	hazel hall-roberts, d. agarwal, + authors s. cowley 	biology, medicine 	alzheimer's research & therapy 	 	 	pdf save alert research feed ... ... references showing - of references bcl-xl regulates mitochondrial energetics by stabilizing the inner membrane potential 	y. chen, m. aon, + authors j. m. hardwick 	biology, medicine 	the journal of cell biology 	 	 	pdf 	view excerpt, references background save alert research feed chchd inhibits apoptosis by interacting with bcl-x l to regulate bax activation 	y. liu, h. clegg, + authors y. zhang 	biology, medicine 	cell death and differentiation 	 	 	pdf save alert research feed mnrr (formerly chchd ) is a bi-organellar regulator of mitochondrial metabolism. 	s. aras, minbo bai, i. lee, r. springett, m. hüttemann, l. grossman 	biology, medicine 	mitochondrion 	 	 	highly influential 	view excerpts, references background save alert research feed metabolic control of cell death 	d. green, l. galluzzi, g. kroemer 	biology, medicine 	science 	 	 	 	view excerpt, references background save alert research feed discovering mechanisms of signaling-mediated cysteine oxidation. 	l. poole, kimberly j. nelson 	chemistry, medicine 	current opinion in chemical biology 	 	 	pdf 	view excerpts, references background save alert research feed reactive oxygen species in cancer 	geou-yarh liou, p. storz 	biology, medicine 	free radical research 	 	 , 	 	view excerpt, references background save alert research feed systematic analysis of the twin cx( )c protein family. 	sebastian longen, melanie bien, + authors j. riemer 	biology, medicine 	journal of molecular biology 	 	 save alert research feed cysteine residues exposed on protein surfaces are the dominant intramitochondrial thiol and may protect against oxidative damage 	r. requejo, t. hurd, n. j. costa, m. murphy 	chemistry, medicine 	the febs journal 	 	 	 	view excerpts, references background save alert research feed oxygen-dependent expression of cytochrome c oxidase subunit - gene expression is mediated by transcription factors rbpj, cxxc and chchd 	s. aras, o. pak, + authors l. grossman 	biology, medicine 	nucleic acids research 	 	 	pdf save alert research feed a mitochondrial origin for frontotemporal dementia and amyotrophic lateral sclerosis through chchd involvement. 	s. bannwarth, s. ait-el-mkadem, + authors v. paquis-flucklinger 	biology, medicine 	brain : a journal of neurology 	 	 	pdf save alert research feed related papers 	abstract 	topics 	 citations 	 references 	related papers stay connected with semantic scholar sign up about semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue petroleum exploration and environmental conservation: abstract association round table any interruption of our foreign energy supplies would have a dramatic effect on our economy and security and would show the dangerous results of the lack of a coherent and positive energy policy. there are very few discovered but undeveloped oil reserves in the u.s. except on the north slope, and those probably cannot be made available before . though the recent npc-aapg study indicates almost bilhon bbl of undiscovered but expectable recoverable u.s. reserves, any large increase in ex- ploratory effort to find them cannot have any great effect on our crude deficit before because of the necessary lead times. it is obvious, however, that certain steps can and should be taken immediately to encourage or to cause such an increase so that the period of danger to our economy and security will be as brief as possible. fitzgerald, d. m., and a. h. bouma, dept. oceanogra- phy, texas a&m univ., college station, tex. consolidation studies of deltaic sediments the texas colorado river delta, which built across mata- gorda bay between and , was selected for consolida- tion research. the objectives were to observe structural changes which occur wjien deltaic sediments undergo primary consoli- dation, and to correlate these consohdated sedimentary struc- tures with those reported from ancient deltaic environments. double cores were collected along a traverse parallel with the main river channel in the southeast lobe of the delta. one core was sput lengthwise, described, and radiographed. an analo- gous undisturbed section of the second core was then selected for consohdation. consolidation, through vertically compressing the sediments, partly creates new structures or makes poorly visible structures more discernible. it was noted in some cases that convolute laminations and recumbent folding formed after sections con- taining parallel laminations were consolidated. it was also ob- served that apparent homogeneous sections, after compaction, changed structurally to reveal parallel laminations. consequently, it should be realized that consolidation will aitect unconsolidated sediments and that these changes should be considered when comparing recent and ancient environ- ments. floyd, b. l., independent, portland, tex. drilling funds and the energy crisis (no abstract submitted) galloway, w. e., continental oil co., exploration re- search div., ponca city, okla. slcnihcance of r e s e r v o i r d i a g e n e t i c alteration for petroleum exploration, gulf of alaska tertiary basin the tertiary clastic section of the gulf of alaska sedimen- tary basin is considered an important potential future petro- leum province. considerable work in the onshore area has been carriesl out by industry preparatory to a projected sale of fed- eral leases on the continental shelf. examination of numerous samples collected from measured sections in oligocene to pleis- tocene strata has shown that the sandstones are mineralogically immature and unstable. diagenetic alteration of these potential reservoir sands at shallow to intermediate depths of burial has resulted in the ubiquitous formation of authigenie clay rims and coats around detrital grains and of poie-filling zeolite cements. these diagenetic alterations adversely affect both porosity and permeability and will provide a major limitation on the thick- ness of the sedimentary section than can be considered pros- pective. a compaction versus depth gradient, which is related to the sandstone porosity gradient, can be determined in off- shore areas by combination of seismically derived interval, velocity depth profiles, with a velocity-density calibration based on well data from the hecate strait (a geologically similar pacific margin basin lying off british columbia). the resultant density configuration can be cross checked by gravity modeling along the same seismic line. work on a line off cape yakataga shows that the prospective section is characterized by a high velocity and density gradient, indicating rapid loss of reservoir porosity with increasing depth of burial, as predicted by the onshore diagenetic model. semiquantitative evaluation of the compaction profile using the onshore reservoir data suggests that even in the youngest sections porosity decreases to less than % at depths of , to , ft. guevara, e. h., and r. garcia, bur. econ. geology, univ. of texas at austin, austin, tex. depositional systems and oil-gas reservoirs in queen city formation (eocene), texas regional surface and subsurface studies indicate that thick deltaic (queen city formation) and thin shelf (reklaw and weches formations) sequences compose the stratigraphic inter- val between the top of the wilcox group and the base of the sparta formation. in east texas, the queen city formation accumulated as part of a high-constructive, lobate delta system; and in south texas, as part of a high-destructive, wave-domi- nated delta system. in south texas, principal facies are mean- der-belt sand, lagoonal mud, stacked coastal barriers, and pro- delta-shelf mud facies; in east texas, delta plain, delta front, and prodelta facies are dominant; and in central texas, the principal facies are strandplain sands originated by southwest- ward longshore drift of sediments from the high-constructive delta system. facies distribution, composition, and size of the deltas in east texas are similar to lobes of the holocene high-construc- tive mississippi delta system and to ancient deltas in the lower part of the wilcox and in the jackson groups of the gulf coast basin. fluvial-deltaic sediments of south texas are comparable to pleistocene high-destructive wave-dominated facies on the surinam coast, to the holocene rhone delta system, and to ancient deltas in the upper part of the wilcox group. queen city deltas prograded gulfward over shelf muds and glauconites of the reklaw formation; they are overlain by comparable shelf facies of the weches formation. in east texas, deltaic facies wedge out eastward; terrigenous elastics of the high-destructive deltas extend southward into mexico. hydrocarbons are produced from thin strike-oriented sands downdip from the belt of maximum sand thickness of the high- destructive deltas in south texas; only a minor amount of oil and gas has been obtained from delta front and distributary channel sands of the high-constructive deltas in east texas. haas, m. w., vice-president for exploration, humble oil & refining co., houston, tex. petroleum exploration and environmental conservation u. s. faces energy crisis.—v. s. energy demands will nearly double by . all our principal sources of fuel will be needed to meet the demand; if domestic supplies cannot keep pace, we face increasing reliance on foreign oil. energy and public iands.—much of u. s. energy potential, including offshore oil and gas reserves, is on publicly owned lands. potentially productive acreage in the federal and state domain should be made available to industry in a manner designed to maximize timely development. environmental delays.—a principal factor in delaying explo- ration of frontier areas is environmental concern. many envi- ronmental objections are founded on the argument that oil and gas development is incompatible with other uses of the same land or water area. compatible use.—if exploration is to proceed at a pace con- sistent with national needs in the future, the concept of compat- ible multiple use of lands must be established as national pol- icy. industry must demonstrate from available examples that this concept is sound and results in maximum benefits to public and private interests. geologisls must contribute.—petroleum geologists should bring their knowledge to bear on public environmental issues and work for reasoned solutions based on scientific fact. much exploration today awaits public consent; geologists must aid in showing pubuc that energy-environmental problems can be association round table solved at the same time, without denying the nation the benefits of adequate, low-cost energy and an environment of acceptable quality. halbouty, m. t., consulting geologist and petroleum en- gineer, houston, tex. oil is found in the minds of men wallace pratt, one of the great and most eminent petroleum geologists of our time, staled that "oil is found in the minds of men." it seems that in the decades from to , a span of more than years, the explorationists have forgotten this one fact. we have depended on black boxes, green boxes, small computers, big computers, and first-dimensional, second-di- mensional, and third-dimensional processes and techniques to tell us where to drill a well. this dependence on instruments has been our profession's greatest mistake and one which was compounded by the petro- leum industry which supported and perpetuated this practice. in fact, petroleum management forced our profession to cease thinking about petroleum being foimd in the minds of men and told us that it could be better found in the transistors of the black boxes and the computers. a point has been reached where we cannot find the so-called structures on land with these gadgets. therefore, we have said to ourselves, and industry has said to itself, "a new break- through is needed." unfortunately, in reference to this need, geologists and industry are still thinking of new gadgets for the "breaithrough." the breakthrough should be in the minds of the explorationist. this should be the paramoimt tool. all of the other gadgets, old and new, will have to be supplements to the minds of men. hester, n. c , illinois state geol. survey, urbana, ., and j. b. risatti, dept. geology, univ. of illinois, urbana, . n a n n o p l a n k t o n blostratigraphy and sedimentary p e t r o l o o v of a verxical facies sequence crossing the c a m p a n i a n - m a e - strichtun b o u n d a r y i n c e n t r a l a l a b a m a on the basis of the occurrence of calcareous nannoplankton in upper cretaceous sediments, exposed in a series of road cuts near pine level, alabama, the sequence is placed in the upper- most kamptnerius magnihcus zone, the tetralithus aculeus zone, and the lower cbiastozygus initialis zone (campanian- lower maestrichtian). the cusseta sand lithology, which is considered to be of campanian age in western georgia and eastern alabama, is shown to be basal ripley or maestrichtian at this locality, based on the occurrence of cbiastozygus mi- tialis. this age difference suggests that the clastic wedge, build- ing southeastward from central georgia and represented by the cusseta sand in east and central alabama, is time-transgressive as the unit progrades from east to west. although a demopolis chalk hthology (calcareous clay) ap- pears above the basal ripley sand (cusseta sand), it is not campanian as suggested by previous workers, but is instead lower maestrichtian. through the use of planktonic-benthonic foraminiferal ratios, textural analyses, clay mineral ratios, and stratigraphic and biogenic structures, the following sedimentary environments, in vertical sequence, were estabfished: ( ) delta-front silts and sands (regressive), ( ) offshore clay (transgressive), ( ) marginal- shelf sands (basal ripley), ( ) offshore clays (transgressive), and ( ) barrier bar-shoal sand complex (regressive). the gradational boundaries between the various facies pro- duced by a fluctuating strand demonstrates that there is no major break in the sedimentary record in crossing the campa- nian-maestrichtian boundary. hinds, g. w., photogravity co., inc., houston, tex. gulf coast photogeologic applications the gulf coast is an important province for photogeologic apphcations even though much of it is of low dip and low relief and commonly covered by pleistocene terrace deposits. the gulf coast is a very active and dynamic province, char- acterized by clastic sediments that were laid down very rapidly. as a result the sediments are out of equilibrium and consider- able compaction and settling have occurred, and many struc- tures have formed. it is this movement and adjustment, acting throughout geologic time, that allow a subsurface structure to continually extend toward the surface, where it can be detected by subtle photogeologic techniques. photogeologic or photogeomorphic techniques, including analyses of drainage, topography, vegetation, deposition, and lineation, can definitively locate surface structures. many of the gulf coast oil and gas fields have surface expression. fields with good expression include those located in areas of current exploration interest, such as sunniland and felda in south florida, flomaton and blackjack creek in the alabama-flor- ida jurassic play, edgewood and fruitvale in east texas, and big wells and los tiendos in southwest texas. many other fields have good expression including citronelle, blacklake, neale, reyes, mathis, and north government wells. normally, photogeologic interpretation must terminate at the coastunes, but a relatively new sonar-subsea mapping device allows exploration to continue onto the shelf areas. the institut fran ais du petrole has developed a wide-range scanning sonar that can provide sea-bottom sonar images that rival aerial pho- tographs. holmes, c. w., and e. a. slade, u.s. geol. survey, cor- pus christi, tex. distribution and isotopic composition of uranium in a lower south texas river and estuary the uranium concentration and isotopic composition of wa- ter and suspended sediment from a south texas river and estuary were determined by alpha-spectroscopy. the average dissolved uranium concentration and radioactivity ratio (u'"/ v") of the river water were determined to be . ug/ and . , respectively. water from a tributary of the river was found to contain an average dissolved uranium concentration of . ug/ with an isotopic radioactivity ratio of . . close inspec- tion of the lateral concentration and isotopic activity ratio of uranium revealed an increase below the confluence of a tribu- tary and the river. a model was derived based on equations used in isotopic dilution analysis, which predicts these increases within analytical error. this model may be useful in future studies to locate extraneous uranium within the hydrologic environment. johnson, c. m., a. h. bouma, and w. r. bryant, dept. oceanography, texas a&m univ., college station, tex. bottom characterishcs of northern gulf of mexico continen- tal shelf photographs of the gulf of mexico continental shelf floor between panama city, florida, and galveston, texas, were examined for evidence of sediment texture, structure, and biq- logic activity. sediment size is distinctively coarser in areas of reef growth near the continental slope. bioturbation was recog- nized by the presence of burrows, mounds, furrows, tracks, and excrements. water turbidity of varying degrees at times ob- scured the real water-sediment interface. current direction and inferred velocity were indicated by compass and sediment cloud. a program of extensive photography, complemented by shallow cores, grab samples, and box samples, is needed to understand fully the different physiographic provinces of the gulf of mexico and their local variations. jones, b. r., gravilog corp., houston, tex. use of downhole gravity data in formation evaluation it has been shown by several workers that the downhole stalk model of membrane fusion: solution of energy crisis stalk model of membrane fusion: solution of energy crisis yonathan kozlovsky and michael m. kozlov department of physiology and pharmacology, sackler faculty of medicine, tel-aviv university, ramat aviv, tel aviv , israel abstract membrane fusion proceeds via formation of intermediate nonbilayer structures. the stalk model of fusion intermediate is commonly recognized to account for the major phenomenology of the fusion process. however, in its current form, the stalk model poses a challenge. on one hand, it is able to describe qualitatively the modulation of the fusion reaction by the lipid composition of the membranes. on the other, it predicts very large values of the stalk energy, so that the related energy barrier for fusion cannot be overcome by membranes within a biologically reasonable span of time. we suggest a new structure for the fusion stalk, which resolves the energy crisis of the model. our approach is based on a combined deformation of the stalk membrane including bending of the membrane surface and tilt of the hydrocarbon chains of lipid molecules. we demonstrate that the energy of the fusion stalk is a few times smaller than those predicted previously and the stalks are feasible in real systems. we account quantitatively for the experimental results on dependence of the fusion reaction on the lipid composition of different membrane monolayers. we analyze the dependence of the stalk energy on the distance between the fusing membranes and provide the experimentally testable predictions for the structural features of the stalk intermediates. introduction the ability to fuse is shared by biological membranes, consisting of phospholipid bilayers with embedded and bound membrane proteins, and by artificially formed purely lipid membranes. normally, the membranes are mechani- cally stable. this is guaranteed by powerful hydrophobic effect (tanford, ), which drives self-assembly of the lipid molecules into bilayer and maintains the bilayer integ- rity. fusion involves drastic although local changes in the initial membrane structure. obviously, the membrane con- figurations emerging at the intermediate stages of fusion require input of energy and, hence, represent energy barriers the membranes have to overcome on the way to the new fused state. these configurations referred to as the fusion intermediates largely limit the rate of the fusion reaction. modeling the lipidic fusion intermediates has a more than two decades history (chernomordik et al., a). al- though, at the early stages, several different structures have been suggested, only one of them, called fusion stalk (gin- gell and ginsberg, ; kozlov and markin, ), is currently recognized to adequately describe the transition stage of membrane fusion (chernomordik et al., a; jahn and südhof, ). fusion stalk is a local lipidic connection between the proximal (contacting) monolayers of the fusing membranes (fig. ). at the stage of stalk formation, the distal mono- layers of the membranes are still separated, and the achieved state is referred to as hemifusion. a physical model of the fusion process, based on this hypothetical intermediate and referred to as the stalk model, has been developed in a series of works (kozlov and markin, ; markin et al., ; chernomordik et al., ; leikin et al., ; kozlov et al., ), further modified by siegel ( , ) and, re- cently, by kuzmin et al. ( ). a number of important predictions of the stalk hypothesis have been verified experimentally for fusion of protein-free lipid bilayers and for some examples of biological fusion. to start with, the hypothesis suggests that merger of the proximal monolayers of the membranes precedes merger of their distal monolayers. indeed, the existence of a distinct hemifusion stage has been documented for different exper- imental systems based on protein-free bilayers (chanturiya et al., ; chernomordik et al., a, b; lee and lentz, ; pantazatos and macdonald, ) and for fusion of biological membranes (chernomordik et al., ; kemble et al., ; leikina and chernomordik, ; melikyan et al., ; song et al., ). although these data substan- tiated the important positions of the model, more detailed theoretical analysis revealed major problem with the phys- ical basis of the approach. recent estimates (siegel, , ) suggested that the energy of the stalk intermediate is too high to allow its formation even for lipid membranes demonstrating very fast fusion, such as bilayers formed from dioleoylphosphatidylethanolamine (dope). resolv- ing this “energy crisis” has been of utmost importance for understanding physical mechanisms of stalk formation and membrane fusion. in this work, we suggest a new structure for the stalk intermediate, which differs in important details from that considered previously. we demonstrate that the energy of this modified structure is considerably smaller than that previously obtained, so that the stalk intermediate can be formed in the experimental conditions. a remarkable result of our model is that the stalk energy practically does not depend on the distance between the fusing membranes. the submitted july , and accepted for publication november , . address reprint requests to michael m. kozlov, tel-aviv university, sackler faculty of medicine, dept. of physiol. & pharmacol., ramat-aviv, tel-aviv , israel. tel.: � - - - ; fax: � - - - ; e-mail: misha@picard.tau.ac.il. © by the biophysical society - / / / / $ . biophysical journal volume february – model accounts for the reported experimental data on mod- ulation of the fusion reaction by lipid composition of the membrane monolayers and provides the experimentally testable predictions for the structural features of the stalk intermediate. energy crisis of the stalk model criterion for energy of fusion intermediate as mentioned above, the fusion intermediates are not sup- posed to represent the final structures adopted by the mem- branes. the energy of a fusion intermediate, fint, may be larger than the energy of the initial membranes, f . in the case where fint is too large compared to f , formation of the fusion intermediate becomes improbable. estimations based on the experimental investigations of the electrical break- down of membranes (chernomordik and abidor, ; weaver and mintzer, ) show (kuzmin et al. ) that the maximal value of the relative energy, fbar � fint � f , that the membrane can overcome within a characteristic time scale of biological fusion is about fbar � kt. energies predicted by the previous versions of the stalk model fusion of two initially separated membranes requires a number of steps, which include a local approach to small distances; some kind of perturbation of structure of the apposing monolayers such as, for example, their rupture in the region of the close contact; merger of the apposing monolayers; and formation of the lipid stalk between the membranes (leikin et al. ). because of complexity of quantitative evaluation of the early stages of fusion, the major efforts have been devoted to modeling the lipid stalk, whose energy is considered as a lower bound to the true energy barrier of the fusion reaction (siegel, ; cherno- mordik et al., a). originally, the stalk membrane was assumed to have a semitoroidal shape (fig. a) (kozlov and markin, ). depending on conditions, the stalk may have a tendency to expand, resulting in dimpling of the distal monolayers to- ward each other and formation of a hemifusion diaphragm (kozlov and markin, ; markin et al. ). the inter- mediate structure of an early stage of stalk expansion was called the transmonolayer contact (tmc) (siegel, ) (fig. b). the most obvious feature of the stalk and tmc is a strongly curved shape of their membranes (fig. ). there- fore, the original version of the model (kozlov and markin, ; markin et al. ; leikin et al. ; kozlov et al., ) was based on the analysis of the stalk bending energy. for a membrane composed of a lipid with common prop- erties such as dioleoylphosphatidylcholine (dopc), the en- ergy of stalk was computed to be close to kt, whereas formation of tmc required an additional increase of the energy. for a membrane consisting of dope, a lipid having an internal tendency to bend and form inverted hexagonal phase (gruner et al. ; rand et al., ), the stalk energy was estimated as only a few kt. the further development of the stalk model by siegel ( , ) revealed an additional considerable contribu- tion to the energy. it is related to the so-called hydrophobic interstices (turner and gruner, ), which result from packing the hydrocarbon chains of lipid molecules around the hydrophobic regions where the portions of differently curved lipid monolayers contact each other (fig. ). a tendency of the system to minimize the interstices results in bending of the distal membrane monolayers, another issue, which has been neglected in the original stalk model. the value of the interstice energy can be estimated based on the experimental data on mesophase behavior of aqueous solutions of lipids (siegel, ). the resulting overall energies of the fusion intermediates turned out to be much larger than originally predicted. for the aqueous distance of � nm between the fusing membranes, which corresponds to an equilibrium intermembrane spacing in pure lipid sys- tems (rand and parsegian, ), the stalk energies for membranes consisting of dopc and dope were predicted figure previous model for stalk intermediates. (a) fusion stalk. (b) transmembrane contact (tmc). the structures are axially symmetric. stalk model of membrane fusion biophysical journal ( ) – to equal kt and kt, respectively. even few times larger stalk energies have been obtained for the aqueous distances between the membranes of � nm (siegel, ) corresponding to viral fusion (skehel and wiley, ). recently, another attempt has been undertaken to modify the stalk model (kuzmin et al., ) based on a more sophisticated way to estimate the energies of the hydropho- bic interstices. the authors have chosen to present the energy with respect to a hypothetical highly stressed dim- pled state of the membranes. relating their results to the initial flat shape of the membranes gives the stalk energy of more than kt, even exceeding the results of the modified model of siegel ( ). challenge for the present research comparing the energies predicted by the modified model (siegel, , ) with the above criterion for fusion intermediate leads to the conclusion that the stalk cannot form in a real system. in contrast, membranes do fuse, and the major qualitative predictions of the original model (koz- lov and markin, ; markin et al., ; chernomordik et al., ) on modulation of the fusion reaction by the membrane lipid composition have got a solid experimental confirmation (chernomordik et al., a). how to recon- cile this inconsistency? a straightforward suggestion is that the structure of the stalk intermediates is different from that suggested previously. a more optimal structure possessing a smaller energy, which can be overcome due to thermal fluctuations or protein refolding has to be found. in the following, we propose and analyze such a structure. structure of fusion stalk the excessive stalk energy predicted by the earlier analysis (siegel, ) results from the energy price of the hydro- phobic interstices, which have been extensively discussed in the context of packing the hydrocarbon chains of lipid molecules in the inverted hexagonal (hii) phases (gruner, ; seddon, ; turner and gruner, ; kirk et al., ; tate and gruner, ; sjölund et al., ; duesing et al., ; rand and fuller, ). recently, a model of the hii phase has been developed proposing that the hydro- phobic interstices are filled due to tilting the hydrocarbon chains with respect to the monolayer surface (hamm and kozlov, , ). this tilt model succeeded to interpret quantitatively the phase diagram of the aqueous solutions of glycolipids (hamm and kozlov, ). we suggest the stalk structure based on the tilt model for the hydrophobic interstices, as illustrated in fig. . to emphasize the major features of our model, let us compare figs. and . the hydrophobic void (fig. ) is filled (fig. ) due to an oblique packing of the hydrocarbon chains with respect to the membrane surface. this results in a sharp corner in the monolayer profile. in the cross-section of stalk, the corner is located between two adjacent molecules (fig. ) so that none of them suffers a strong bending. in addition to tilt of the hydrocarbon chains, the membrane is curved close to the corner (fig. ). the membrane curvature and tilt of the chains smoothly relax along the membrane surface to the flat state with vanishing tilt. the illustration in fig. implies that several hydrocarbon chains terminate simultaneously at the center of the stalk structure. this may lead to chain-packing problems similar to those revealed by computer analysis of micellar struc- tures, where only one chain has been shown to occupy the center of a micelle. however, the stalk structure (fig. ) is similar geometrically to the inverted hexagonal (hii) phases rather than to micelles. computer analysis of hii phases (gido et al., ) confirms a possibility of formation of sharp corners filled by hydrocarbon chains similar to that presented in fig. . terminologically, the suggested structure (fig. ) is the fusion stalk and the tmc at the same time. indeed, on one hand, it corresponds to the very first merger of the proximal monolayers of the fusing membranes and, on the other, the distal monolayers are already deformed in a way that they touch each other, although point-wise. elastic model for stalk intermediate to proceed, we need a physical model describing the elastic energy of a complex deformation of the membrane mono- layers, which involves bending of the monolayer surface and tilt of the hydrocarbon chains of lipid molecules. monolayer shape and deformations we apply the approach developed in detail recently (hamm and kozlov, , ), which is, in turn, based on the h r n nφ τ ϕ figure tilt model for stalk and tmc. the shape is axially symmet- ric. illustration of notations used: n is the unit vector of the normal to the monolayer surface, n is the director of a hydrocarbon chain, � is the tangential unit vector, � is the tangential angle, � is the tilt angle; h is the intermembrane distance; r is the stalk width. the presented relationship between the monolayer thickness and the dimensions of the hydrocarbon chains is approximately equal to the real one. kozlovsky and kozlov biophysical journal ( ) – ideas of the classical works by frank ( ) and helfrich ( ). we consider a lipid monolayer having, in the initial state, a flat shape (fig. a). to characterize the geometry of the monolayer, we use the dividing surface (gibbs, / ), which lies along the interface between the polar groups and the hydrophobic interior and has been shown for par- ticular lipids to play a role of the neutral surface (kozlov and winterhalter, a,b; kozlov et al., ; leikin et al., ). the monolayer shape will be identified with the shape of its dividing surface. to describe it mathematically, we define in each point of the dividing surface a unit normal vector n (fig. ). the average orientation of a hydrocarbon chain is ex- pressed by a unit vector n referred to as the chain director. in the initial state, the chains are perpendicular to the dividing surface, meaning that n coincides with n (fig. a). the area of the chain cross section at the dividing surface is denoted by a. we consider two deformations of the mono- layer: bending, resulting in deviation of the monolayer shape from the initial flat one (fig. b); and tilt of the hydrocarbon chains, resulting in deviation of the chain director n from the surface normal n (fig. , c and d). we will assume the chain area a to remain constant, meaning that the monolayer does not undergo lateral stretch, because the corresponding membrane rigidity (rawicz et al., ) is considerably larger than those of tilt (hamm and kozlov, , ) and bending (niggemann et al., ). the volume of a hydrocarbon chain, v, does not change in the course of membrane deformations, because the hydro- carbon moiety of a lipid molecule is practically incompress- ible. a simple geometrical consideration based on fig. d, and accounting for constancy of v and a, shows (hamm and kozlov, ) that the deformation of tilt results in stretch of the hydrocarbon chains with respect to their initial length. at the same time, the monolayer thickness measured per- pendicularly to the membrane surface remains constant. the stretch of the chains accompanying their tilt allows for filling the hydrophobic voids of the stalk intermediate. elastic energy the elastic energy of a monolayer originates primarily from the hydrocarbon chains (helfrich, ; ben-shaul, ). within the continuous description, the major contributions to the elastic energy arise, on one hand, from the splay of the chains (frank, ; helfrich, ) and, on the other, from uniform tilt of the chains with respect to the monolayer surface (mackintosh and lubensky, ). energy of splay splay of the hydrocarbon chains is illustrated in fig. , b and c. it can result from two different deformations (hamm and kozlov, , ): bending of the monolayer surface, whereas the hydrocarbon chains remain parallel to the sur- face normal, n � n, (fig. b), and variation of the molec- ular director n along the monolayer surface, whereas the surface remains flat (fig. c). this means that the chains exhibit tilt, n � n, which changes along the monolayer plane. figure deformations of a monolayer. (a) the initial undeformed state. (b) bending with vanishing tilt. (c) splay of the chains resulting from changing tilt in a flat monolayer. (d) homogeneous tilt of the chains. (e) mutual compensation of bending and tilt resulting in a bent membrane with vanishing splay of the chains. stalk model of membrane fusion biophysical journal ( ) – obviously, combinations of these two deformations also result in splay of the chains. mathematically, splay of the chains, denoted by j̃, can be presented for the two cases above and their combinations in the same form (helfrich, ; hamm and kozlov, ) j̃ � div n, ( ) where div n denotes the covariant divergence of the director n along the monolayer surface. in the case, of pure bending, n � n, the splay (eq. ) is given by j̃ � div n, and, according to the general geometrical relationship, is equal to the total curvature, j, of the monolayer surface (thomas, ). for the case of varying director, eq. is analogous to splay in a liquid crystal (frank, ). the energy of splay per unit area of the dividing surface can be expressed as (hamm and kozlov, , ) fs � � � � �div n � j̃s	 , ( ) where j̃s is the spontaneous splay and � is the splay modulus of the monolayer, the two characterizing the monolayer elastic properties. the spontaneous splay, j̃s, coincides with the spontaneous curvature, js, introduced by helfrich ( ) for the cases where splay originates solely from the mono- layer bending. the spontaneous splay is related to the ef- fective shapes of lipid molecules constituting the monolayer (israelachvili et al. ; de kruijff and cullis, ). for a common lipid such as dopc, the spontaneous splay is slightly negative, j̃s � � . nm � (chen and rand, ); for dope, this value is strongly negative, j̃s � � . nm � (kozlov et al., ; leikin et al., ); whereas, for lysolipids and, specifically, for lysophosphatidylcholine (lpc), the spontaneous splay is positive, j̃s � . nm � (fuller and rand, ). the spontaneous splay of a mixed monolayer can be estimated as an average over the mole- cules constituting the monolayer (kozlov and helfrich, ). the splay modulus � coincides with the helfrich bending modulus (helfrich, ; hamm and kozlov, ). its value, � � kt, measured for monolayers (niggemann et al., ; leikin et al., ), will be used for calculations below. the major assumptions of the model (eq. ) are that the hydrophobic moiety of a lipid monolayer can be described as an elastic continuum and that the splay is small compared to the monolayer thickness �, so that �div n� � � . while accounting for a combined deformation of bending and tilt, eq. represents the helfrich elastic model (helfrich, ) for the case of pure bending. energy of tilt uniform tilt of the hydrocarbon chains is illustrated in fig. d. tilt can be quantified by a vector t defined as (mac- kintosh and lubensky, ; hamm and kozlov, , ) t � n n � n � n, which is parallel to the dividing surface and characterizes the deviation of the director n from the surface normal n (fig. d). the corresponding energy per unit area of the monolayer is given by (mackintosh and lubensky, ; hamm and kozlov, ) ft � � �t � t , ( ) where �t is the tilt modulus (hamm and kozlov, ). the major contribution to the tilt modulus �t results from the stretch of the hydrocarbon chains. this follows from com- parison of the model estimation (hamm and kozlov, ) with the value of �t � . n/m, found from fitting the experimental results on phase transitions in lipid systems (hamm and kozlov, ). the latter value for the tilt modulus will be used for computations below. the qua- dratic model (eq. ) assumes small absolute values of tilt, �t� . main equations we relate the total energy ftot consisting of the energies of splay (eq. ) and uniform tilt (eq. ) to that of the initial flat state with vanishing splay and tilt, j̃ � , t � . the resulting energy per unit area of the monolayer is ftot � � � � �div n � j̃s	 � � �t � t � � � � j̃s . ( ) to compute the total elastic energy of a monolayer, fmon, the energy ftot has to be integrated over the area a of the dividing surface, fmon � �ftot da. ( ) in appendix a, we describe the details of calculation of the stalk energy. energy and shape of stalk: results our analysis is aimed at describing the energy of the stalk intermediates formed in the course of different fusion reac- tions including, on one hand, fusion of pure lipid vesicles and, on the other, fusion of cell and viral membranes me- diated by proteins. in each real system, there are constraints imposed on the configuration of the fusion site. we char- acterize these constraints by two parameters (fig. ). first, the distance r from the center of the stalk, to the region where membranes have to become flat and parallel, is referred as the width of the stalk base. second, the distance kozlovsky and kozlov biophysical journal ( ) – between the membrane middle planes h is referred to as the intermembrane distance. in the case of fusion of purely lipid membranes, the stalk width r is limited by the vesicular radius, which is usually larger than nm. the intermem- brane distance h, in this case, cannot become considerably smaller than its equilibrium value of � nm (rand and parsegian, ), which is determined by the whole set of the interbilayer interactions. in the case of fusion of biological membranes, the con- straints for both h and r are determined by the protein architecture of the membrane contact and can vary consid- erably depending on the type of fusing cells or viruses. for example, in the case of fusion of influenza virus with target cell, the intramembrane distance h is determined by the length of ha molecule, h � nm. the stalk intermediate is supposed to form within a membrane domain, which does not contain proteins (kozlov and chernomordik, ) so that the dimension of such domain limits the width of the stalk base r. to be able to describe all possible types of fusion reac- tion, we analyze the stalk energy f for a large range of the intermembrane distances h and the stalk widths r. how- ever, the calculations illustrating more special features of the model, such as dependence of the stalk energy on the spontaneous curvatures of the monolayers, will be performed for the equilibrium intermembrane distance h � . nm. symmetric membranes to understand the major features of the fusion stalk, we first calculated its energy and structure for the case where the two membrane monolayers have the same spontaneous splay, j̃s � � . nm � , corresponding to the typical lipid dopc. the values of the monolayer modulus of splay and tilt are taken to be � � � � j and �t � . n/m (hamm and kozlov, ). stalk energy dependence of the stalk energy f on the stalk width r and intermembrane distance h has the shape of a canyon, which descends monotonically with growing r and h. this means that the stalk has a general tendency to expand its base and length. if the geometrical constraints limiting r and h are lifted, what corresponds to fusion of giant vesicles, the stalk becomes infinitely wide (r �) and long (h �), and its energy approaches the value of � kt. in the case where the expansion of the stalk base is limited by a specific width r, an optimal intermembrane distance hopt exists providing the stalk with a minimal energy. dependence of hopt on the stalk width r is illus- trated in fig. by diamonds, and the related variation of the stalk energy f along the bottom of the canyon is presented in fig. by stars. to demonstrate a strong increase of the elastic energy of the stalk, f, at small r and hopt, we started our analysis from hopt � . nm, which is slightly below the equilibrium intermembrane distance h � . nm (rand and parsegian, ). it should be noted that, within the small range of h between . nm and . nm, there is some positive contribution to the overall stalk energy from the repulsive interaction between the membranes. as a result, the whole energy of stalk in this region is slightly larger than that presented in fig. (stars) for nm r nm. if the stalk length is limited by a specific intermembrane distance h, the energy f decreases monotonically with growing width r, as represented in fig. for several values of h. the dependences f(r) can be described by a charac- teristic stalk width rc. we define rc as a width where the slope of the curve f(r) equals (df/dr)�rc � � kt/nm. the energy decreases sharply in a range of small stalk width, r rc, whereas, for the value of r exceeding the charac- teristic width, r 
 rc, the energy changes slowly and reaches a plateau. the plateau value of the energy, f*, depends on the intermembrane distance h, but this depen- r [nm] f [k t ] h op t [ nm ] figure dependence of the energy f (�) and the optimal intermem- brane distance hopt ({) on the width of the stalk base, r. figure the dependence of the stalk energy f on the width of the stalk r for different values of the intermembrane distance h, as indicated in the figure. stalk model of membrane fusion biophysical journal ( ) – dence is very weak and f* remains below kt for all relevant values of h. the dependence of the characteristic width on the intermembrane distance, rc(h), can be de- scribed by rc � � . � h � . 	 nm. ( ) the above definition for the characteristic width rc is arbi- trary. however, our numerical estimations show that, due to a well-pronounced distinction between the regions of a sharp and slow changes of the energy f(r), the value of rc is rather insensitive to the exact slope, (df/dr)�rc, chosen for its determination. stalk configuration the shape of the stalk surface depends on its width r and the intermembrane distance h. in fig. , a characteristic shape of the stalk is presented. change of the stalk shape with r and h is illustrated in fig. presenting the line whose revolution around the z-axis forms the midsurface of the half stalk. to emphasize the features of the stalk shape, the scale along the z-axis is chosen a few times smaller than that along the r-axis. for intermediate values of r and h, the stalk profile is nonmonotonic, exhibiting a depression be- fore reaching the flat shape (fig. , a–d). the depression becomes broader and deeper with increasing r. for an unconstrained stalk (r �, h �) the surface far from the stalk center approaches the shape of a catenoid (fig. e), the axially symmetric minimal surface characterized by zero total curvature (nitsche, ). this unlimited catenoid-like shape has the energy of � kt mentioned above. effects of spontaneous splay we have computed the influence of the spontaneous splay of the membrane monolayers on the stalk energy for differ- ent values of the stalk width r and intermembrane distance h. within an experimentally relevant range, the qualitative character of this influence turned out to be independent of the specific values of r and h. we present the results (fig. ) for the intermembrane distance h � . nm, correspond- ing to the equilibrium separation in the lamellar phases of egg phosphatidylcholine (rand and parsegian, ), and the stalk width r � nm, which exceeds the characteristic width, rc. the dependence of the stalk energy f on the spontaneous splay of the monolayers, j̃s, is represented by fig. (line ) and is well described by f � ( � � j̃s � �) � kt, where � is the distance between the monolayer neutral surface and the bilayer midplane, � � . nm. for the membrane of dopc, having j̃s � � . nm � (chen and rand, ), the stalk energy is about f � kt, which exceeds, by � kt, the above criterion of stalk formation due to thermal fluc- tuations. for dope characterized by a spontaneous splay of j̃s � � . nm � (kozlov et al., ; leikin et al., ) the stalk energy is strongly negative, f � � kt, meaning that, for this lipid, the stalk is energetically favorable and, hence, does not contribute to the energy barrier of mem- brane fusion. the spontaneous splay of a mixture of differ- r[nm] z[ nm ] a b c d e figure the shape of the stalk profile for constant intermembrane distance h � . nm and different values of the stalk width r. to emphasize the details of the shape, the scale along the z-axis is taken a few times smaller than that along the r-axis. (a) r � nm; (b) r � nm; (c) r � nm; (d) r � nm; (e) r and h are unconstrained. figure dependence of the stalk energy f on the spontaneous splay j̃s of the membrane monolayers (h � . nm, r � nm). ( ) symmetric membrane: the spontaneous splay is equal in the two monolayers. ( ) asymmetric membrane: f as a function of the spontaneous splay of the proximal monolayer, j̃s p, while the spontaneous splay of the distal mono- layer is fixed, j̃s d � � . nm� . ( ) asymmetric membrane: f as a function of the spontaneous splay of the distal monolayer, j̃s d, while the spontaneous splay of the proximal monolayer is fixed, j̃s p � � . nm� . kozlovsky and kozlov biophysical journal ( ) – ent phospholipids can be calculated in a good approxima- tion as a weighted average of the spontaneous splays of the components (see, for example, kozlov and helfrich, ). for example, the energy of a stalk consisting of a dope/ dopc mixture has a value intermediate between the ener- gies of the pure dope and dopc stalks, as represented in fig. by points on the line ( ) corresponding to the weighted spontaneous splays. asymmetric membranes the spontaneous splays of the two membrane monolayers have different effect on the overall stalk energy f. to analyze this issue, we performed computations for asym- metric stalk membrane. line ( ) in fig. represents the dependence of f on the spontaneous splay of the proximal monolayer, j̃s p, while that of the distal monolayer remains constant, j̃s d � � . nm� . the function f(j̃s p) practically coincides with the energy of a symmetric membrane fig. , (line ). in contrast, the dependence of the energy f on the spontaneous splay of the distal monolayer, j̃s d, turns out to be very weak. this is illustrated by line ( ) in fig. , which presents f(j̃s d) at a fixed spontaneous splay of the proximal monolayer, j̃s p � � . nm� . the results, fig. (lines and ), show that the major factor influencing the stalk energy is the spontaneous splay of the proximal monolayer, j̃s p, whereas the distal monolayer practically does not contribute to the effect of the spontaneous splay. discussion we suggest a new structure for the stalk intermediate of membrane fusion (fig. ), which resolves the energy crisis identified in the earlier models. our model adequately in- terprets the experimental results on dependence of fusion on the lipid composition of different membrane monolayers, and gives experimentally testable predictions on the config- uration of the fusion stalk. comparison with previous models why does the suggested approach succeed in solving the energy crisis? the major feature of the present model is that the deformations of the two membrane monolayers are not limited by bending, as previously assumed (kozlov and markin, ; markin et al., ; siegel , ), but involve also tilt of the hydrocarbon chains (hamm and kozlov, , ). the tilt plays a role of an additional internal degree of freedom of the monolayers and allows them to relax the overall energy. specifically, tilt of the chains results in three effects influencing the monolayer energy. ) the hydrophobic voids are filled by the hydro- carbon material so that no “vacuum” is created in the system. the stretch of the hydrocarbon chains necessary to fill the voids is implicated in the chain tilting, and the related energy is accounted by the tilt elasticity �t. ) the overall area of the stalk monolayers is reduced compared to the initially proposed semitoroidal shape (fig. ) due to creation of a corner in the middle of the structure (fig. ). ) splay of the hydrocarbon chains resulting from tilt com- pensates, at least partially, for the splay produced by the monolayer bending (fig. e). in the modified stalk model of siegel ( , ), the tilt degree of freedom has not been considered at all and, therefore, the predicted energy was more than four times larger than that obtained in the present work. in the recent model by kuzmin et al. ( ), the distal monolayers of the stalk are assumed to undergo a localized tilt-like deformation, while the hydrocarbon chains of the proximal monolayer were not allowed to tilt. because of these assumptions, the effect of tilt is drastically limited: the hydrophobic interstices are only partially filled, still leaving vacuum voids; the area of the strongly bent proximal mono- layers, which have a semitoroidal shape, is the same as in the previous models, and, finally, the bending stresses are not compensated by the tilt-induced splay. if the stalk en- ergy resulting from the model by kuzmin et al. ( ) is related to the initial flat shape of the membrane, it turns out to exceed the results of siegel ( ) and to be at least five times larger than the energy predicted by the present ap- proach. as a result, the stalk structure suggested in kuzmin et al. ( ) is far from being the lowest energy fusion intermediate. effects of different lipids according to the experimental data accumulated over the last decades, different phospholipids exhibit distinct prop- erties with respect to membrane fusion. the lipid dopc forms, in aqueous solutions, stable lamellar phases, where the flat lipid bilayers separated by thin ( - to -nm) water gaps do not demonstrate any tendency to fuse spontaneously (rand and parsegian, ). however, addition to these systems of hydrocarbon solvent induces transformation of the lamellae into cylindrical membranes of the inverted hexagonal (hii) phase (sjölund et al., ), the process including multiple fusion of the initial membranes (siegel et al., ; siegel and epand, ; siegel, ). the aque- ous solutions of dope form the hii phase in normal con- ditions at room temperature without any additions. this lipid exhibits a temperature-driven spontaneous transition from lamellar to inverted hexagonal structure at � °c (gawrisch et al., ). this implies that, beginning from this temperature, the dope monolayers have a tendency to fuse spontaneously. indeed, dope and other lipids support- ing hii phase formation (e.g., unsaturated fatty acids and diacylglycerol) promote fusion of protein-free bilayers and protein-mediated fusion (basanez et al., ; cherno- mordik et al., a; chernomordik et al., ; walter et stalk model of membrane fusion biophysical journal ( ) – al., ). in contrast, lysolipids, such as lpc, inhibit fusion. addition of lpc to model (chernomordik et al. ; basanez et al., ; chernomordik et al., ) and biological (chernomordik et al., a; chernomordik et al., ; gaudin, ; melikyan et al., ) membranes considerably inhibited the fusion reaction. promotion and inhibition of fusion by different lipids correlate with their molecular structure, which can be char- acterized by the effective molecular shape (israelachvili et al., ; de kruijff and cullis, ; chernomordik et al., ) or, alternatively, the spontaneous curvature, js (helf- rich, ). the notion of the spontaneous curvature, js, has been recently generalized to the spontaneous splay, j̃s (hamm and kozlov, , ). the spontaneous splay of dope measured experimentally (rand and fuller, ; kozlov et al., ; leikin et al., ) is strongly negative, j̃s dope � � / . nm� ; for dopc, this value can be esti- mated (chen and rand, ) as slightly negative, j̃s dopc � � / . nm� ; and for lpc, the spontaneous splay is posi- tive, j̃s lpc � / . nm� (fuller and rand, ). summa- rizing the experimental results, the more negative the spon- taneous splay of a lipid is, the stronger is its propensity to fuse so that the lipids with the spontaneous splay close to j̃s � � . nm � exhibit spontaneous fusion. the stalk model proposed in the present study readily interprets the dependence of membrane fusion on the lipid composition. for the dopc membranes, our model predicts the energy of the stalk/tmc close to fdopc � kt. this energy is � kt larger than fbar, meaning that fusion should be an extremely rare event. this agrees with a general stability of the dopc lamellar phases (rand and parsegian, ). in contrast, this energy can be easily decreased to a value below fbar to allow for fusion. this can be done by a suitable change in the system compositions such as addition of a hydrocarbon solvent (sjölund et al., ), which is supposed to enter the hydrophobic interstices and partially relieve the membrane stresses. the energy of a stalk inter- mediate we predict for the dope membranes is negative fdope � � kt, which explains the strong tendency of these membranes to fuse. and, finally, a growth of the stalk energy with increasing spontaneous splay (fig. (line )) explains the effective inhibition of fusion by additions of lpc to the membrane monolayers (chernomordik et al., a). effects of different monolayers another result of our model is a prediction of a different influence on stalk formation of the spontaneous splay, j̃s, of the proximal and distal membrane monolayers. according to the earlier model (siegel, ), changes in j̃s of the two monolayers exert a similar effect on the stalk energy f. in contrast, our calculations show that the dependence of the energy f on j̃s is related almost solely to the proximal monolayer (fig. (lines and )). changes in the sponta- neous splay of the distal monolayer, practically, do not influence the energy (fig. (line )). in agreement with our prediction, the experimental investigations showed that ad- ditions of lpc to the proximal monolayer considerably inhibited hemifusion, whereas insertion of the same mole- cules to the distal monolayer had practically no effect on membrane hemifusion (chernomordik et al., ; cherno- mordik et al., ). effects of stalk dimensions our model predicts that, for every given inter-membrane spacing h, the stalk tends to expand its base, thus, increas- ing the width r (fig. ). but the force driving this expansion is strong only as long as the width is smaller than the characteristic value, r rc. for larger values of the width, r 
 rc, the stalk energy almost does not change and, hence, the driving force for the expansion of the stalk base is very small. in practical terms, this means that the stalk tends to expand up to the characteristic width rc, which has values close to the intermembrane distance h (eq. ). this result of the model can be verified experimentally. how does the stalk energy depend on the intermembrane distance h? this question is important for comparing fusion in different systems. indeed, in the pure lipid systems, the typical intermembrane spacing is � nm (rand and parse- gian, ), whereas the distance between fusing cell mem- branes determined by membrane proteins constitutes up to nm (skehel and wiley, ). earlier versions of the stalk model predicted a drastic increase in the energy with the intermembrane distance h (siegel, , ). this would imply that the architecture of the fusion intermediate in the pure lipidic membrane system should differ from that formed between cell membranes. in contrast, our model predicts practically the same energy for the fusion interme- diates of different intermembrane distances, provided that all of them can expand laterally reaching the width of rc. the energy of a stalk with h � nm turns out to be even . kt smaller than that of stalk with h � nm. hence, all the results of our model are valid for different intermem- brane distances. if the width of the stalk base is restricted to values smaller than the characteristic one, r rc, the stalk energy in- creases with the intermembrane distance h (fig. ). this can be expected for fusion of influenza virus, whose mem- brane contains a high density of the fusion protein ha. the lateral spacing between the ha molecules available for stalk formation is close to r � nm (taylor et al., ), whereas the intramembrane distance, as determined by the length of the ha ectodomains, is h � nm (bullough et al., ). according to eq. , in this case, the stalk base does not reach the characteristic width. to avoid a large energy barrier in such a situation, the stalk formation has to be preceded by decrease in h due to dimpling of the kozlovsky and kozlov biophysical journal ( ) – membranes toward each other, as suggested in kozlov and chernomordik ( ). assumptions of the model the suggested model includes several assumptions, which have to be discussed. we use a continuum description of a lipid monolayer, analogous to the frank theory of liquid crystals (frank, ) and the helfrich theory of membrane elasticity (helfrich, ). such description requires, in general, the length scale of deformations to be considerably larger than the dimension of particles constituting the sys- tem. the role of such particles in our case is played by the hydrocarbon chains, and the particle dimension is the diam- eter of the chain projection on the membrane plane, which equals � . nm. according to our results (fig. ), the deformation of splay of the stalk monolayers extends over – hydrocarbon chains, meaning that its length scale is only several times larger than the particle dimension. the deformation of tilt of the stalk intermediate turns out to be even more concentrated and extends over – hydrocarbon chains. although the macroscopic theories are often applied in similar cases, the validity of the results is always ques- tionable and has to be verified by comparison with experi- mental data. a continuum elastic approach of the present work has been used previously for analysis of the energy and the elastic behavior of the inverted hexagonal (hii) phases (kozlov and winterhalter, a,b; kozlov et al., ; leikin et al., ; hamm and kozlov, ), where the ratio between the scale of the monolayer deformations and the chain dimension is the same as for the stalk inter- mediate. this approach proved to describe quantitatively the experimental data on the lamellar– hexagonal phase transitions and the stress–strain relationships of the hii phases. this convinces us that, in spite of the general reservations above, our continuum model adequately de- scribes the stalk intermediate. we make an unusual assumption that the profile of the stalk membrane exhibits a sharp corner. to a first glance, this corresponds to an infinite membrane curvature (j �), which is concentrated within a vanishing area (a ). however, consideration of the structure of the corner in terms of deformations of tilt and splay of the hydrocarbon chains shows that the chains do not exhibit infinite splay at the corner (fig. ). at the same time, the finite splay, analogous to finite curvature, and finite tilt of the hydrocar- bon chains in the region of the corner are taken into account by integrating the energy (eq. ) up to the corner. yet, an additional energy related to the sharp corner may originate from a repulsive interaction between the polar groups of the lipid molecules, resulting, for example, from hydration re- pulsion (rand and parsegian, ; leikin et al., ) or the electrostatic interaction. because this energy is a part of the energy of membrane deformations, to calculate its value, one needs a theory accounting for contribution of the hydra- tion and electrostatic forces to the elastic characteristics of membranes. we are not aware of any systematic treatment of the influence of hydration forces on the elastic moduli of mem- branes. however, a general idea about these effects can be based on the existing models for the hydrations forces (appendix c). based on the qualitative consideration of appendix c, we assume that the hydration of the polar heads provides a negligible contribution to the stalk elastic energy. a model for contributions of the electrostatic interaction to the membrane elasticity has been developed only for small curvatures of the membrane surface (winterhalter and helfrich, ), and, hence, it cannot describe the energy of the corner. we do not consider these effects, assuming the corner to be situated between adjacent uncharged polar heads. the elastic model (eq. ) assumes the deformations of splay and tilt to be smaller than one, �div n � �� , �t� , where � is the monolayer thickness. in reality, in our cal- culations, the deformations of tilt and dimensionless splay approach but never exceed the value of one in a very narrow region close to the corner of the stalk structure. to assure fulfillment of this condition, we limited the ranges of vari- ations of parameters in our numerical procedure. another assumption of our calculation is that, on one hand, the neutral surfaces of the two membrane monolayers are parallel to the membrane midplane, and, on the other, the molecular areas on the neutral surfaces are constant along the whole membrane. because of the relationship among the molecular volume, molecular area, and the splay of the hydrocarbon chains (hamm and kozlov, ), this assumption means that the molecular volume is not strictly conserved in the regions with splay. however this effect turns out to be of a higher order with respect to the dimen- sionless splay. contributions of this order are not taken into account by our hamiltonian (eqs. and ). nevertheless, to estimate the error related to these assumptions, we have numerically computed the deviations of the monolayer sur- faces from the supposed shape, as required by conservation of the molecular volume. we have calculated the related change of the monolayer curvatures and the resulting en- ergy. the determined maximal error of our results consti- tutes %. we did not account in our model for the energy of the saddle-splay deformation (frank, ; helfrich, ) of the stalk monolayer, which is determined by a combination of the deformations of monolayer bending and tilt of the hydrocarbon chains (hamm and kozlov, ). the saddle splay is analogous in the case of simple bending to the gaussian curvature of the monolayer surface. the value of the elastic modulus, �� , determining the energy of the saddle- splay deformation of a monolayer is largely unknown (ben- shaul, ). we are not aware of any experimental inves- tigations that have directly attempted to obtain �� of a stalk model of membrane fusion biophysical journal ( ) – monolayer. the numerical calculations have been per- formed for contribution of the hydrocarbon chains to �� and have shown that its value constitutes less than % of the bending modulus � (szleifer et al., ). based on these results, our estimation of a possible contribution of the saddle-splay deformation to the stalk energy did not exceed few percents of the energy of splay. conclusions to conclude, the present work resolves the energy crisis of the stalk model of membrane fusion. we suggest a specific structure of the stalk intermediate where the major roles are played by deformations of tilt and splay of the hydrocarbon chains. we demonstrate that the stalk intermediates have energies much smaller than those predicted previously and can be formed in real systems due to thermal fluctuations of the membranes. the obtained dependence of the stalk en- ergy on the lipid compositions of the membrane monolayers agrees with the existing experimental data. we predict that the stalk energy, practically, does not depend on the in- tramembrane distance, provided that the stalk base is suffi- ciently free to expand in the lateral direction. appendix a detailed form of equations and boundary conditions lipid monolayers forming the stalk have axially symmetric shapes (fig. ). to present mathematically the dividing surface of such a monolayer, we use the radial coordinate r and the tangential angle � between the radial direction r and the unit vector � tangential to the surface as illustrated in fig. . the dependence �(r) determines the shape of the dividing surface. to express the tilt of the hydrocarbon chains, t, we determine the tilt angle �(r) between the chain director n and the normal to the surface n (fig. ). the absolute value of the tilt vector is �t� � tan�t. (a ) splay (eq. ) of the hydrocarbon chains can be expressed as (appendix b) div n � cos� � r d�rsin�	 dr � cos� � r d�rsin�	 dr . (a ) according to eq. a , for the case of pure bending (fig. b) with vanishing tilt angle, � � , the splay adopts a familiar form of the total curvature of an axially symmetric surface, div n � r d�rsin�	 dr , (see for example helfrich, ). in the case of a flat surface, � � (fig. c), splay is generated by the change of the tilt angle, div n � r d�rsin�	 dr . and, finally, the tangential angle and the tilt angle can cancel each other, � � ��. as a result, the bent surface is characterized by a vanishing splay of hydrophobic chains, div n � . this configuration is illustrated in fig. e. the elastic energy per unit area of the dividing surface of a monolayer, accounting for eqs. , a , and a , is ftot � � � � �cos� � r d�rsin�	dr � cos� � r d�rsin�	dr � js� � � �t � �tan�	 � � �js . (a ) aim of analysis the shape of a lipid bilayer is represented by its middle plane and described by the dependence of the tangential angle of the middle plane �b (fig. ) on the radial coordinate, �b(r). the dividing surfaces of the two lipid monolayers are assumed to be parallel to the middle plane. hence, the tangential angles of the proximal, �p(r), and distal, �d(r), monolayers are directly related to �b(r) of the middle plane (appendix b). the tilt angles in the proximal, �p(r), and distal, �d(r), monolayers are independent functions. the energy of a bilayer is the sum of the energies (eq. ) of the two monolayers. the aim of our analysis is to compute the stalk energy, f, and to determine the shape of the stalk membrane, �b(r), and distribution of tilt in its monolayers, �p(r) and �d(r). outline of analysis the energy f, as obtained by integrating eq. a over the areas of the membrane monolayers, depends on the functions �b(r), �p(r), and �d(r). to find the membrane shape, �b(r), and the distribution of tilt of the hydrocarbon chains, �p(r) and �d(r), we have to minimize the energy f[�b(r), �p(r), �d(r)] with respect to these functions. in the course of minimization, several conditions have to be satisfied: • to ensure that the hydrophobic interstices are filled by the hydrocarbon chains, we set the tilt angles in the center of the stalk, r � , as �d(r � ) � �	/ , and, �p(r � ) � 	/ (fig. ). this also accounts for finite values of splay in the corner. • we require that, at the distance r � r from the center of the stalk, the membranes become flat and parallel with the distance between the membranes’ middle planes equal to h. • far from the stalk center, we require that the tilt of the hydrocarbon chains vanishes, t(r �) � . we calculate the energy and the structure of the stalk intermediate as a function of the following parameters dependent on the membrane proper- ties, which can be modified in the experiments: the spontaneous curvatures js of the membrane monolayers, and the geometrical constraints imposed on the membranes, namely, the distance h between the membranes and the stalk width r. we perform the calculation numerically by the method of finite elements, which is equivalent to solving the euler–lagrange equa- tions. the natural length scale of our calculation is determined by the thickness of the hydrophobic part of lipid monolayer, �. we take egg phosphatidylcholine as a typical lipid and use for calculations the values of its geometrical parameters, and, specifically, � � . nm (rand and parsegian, ). appendix b geometrical relationships expression for splay in this section, we express the splay of the hydrocarbon chains, div n, through the tangential angle of the membrane profile, �, and the tilt angle, kozlovsky and kozlov biophysical journal ( ) – � (fig. ). we consider two lateral unit vectors in the meridional, e�, and equatorial, e , directions. the vector e� coincides with the tangential vector � defined in appendix a (fig. ). the lateral covariant divergence of the chain director representing the splay can be calculated according to div n � dn ds� e� � dn ds e , (b ) where s� and s are the arc lengths measured along the meridional and equatorial directions, respectively. the chain director can be presented as n � cos � � n � sin � � e�, (b ) so that its differential is dn � cos � � dn � sin � � de� � sin � � n � d� � cos � � e� � d�. (b ) the differential of the normal and the tangential meridional unit vectors are dn � e� � d� � sin � � e � d , (b ) de� � �n � d� � cos � � e � d . (b ) the differentials of the arc length in the meridional and equatorial direc- tions are give by ds� � dr cos � (b ) and ds � r � d . (b ) inserting eqs. b –b into eq. b , we obtain for the splay div n � cos � � cos � � d�� � �	 dr � sin�� � �	 r . (b ) the expression (b ) can be presented in a slightly different form (eq. a ). relationship between the tangential angles of the monolayers and the bilayer midplane the tangential angles of the proximal, �p(r), and distal, �d(r), monolayers are related to that of the bilayer middle plane �b(r) by �p�r � � � sin ��r		 � �b�r	, �d�r � � � sin ��r		 � ��b�r	. (b ) appendix c qualitative consideration of effects of hydration forces according to the established view (marčelja and radić, ; gruen and marčelja, ; leikin et al. ), the hydration layer of a membrane is a layer of polarized water, which tends to decay exponentially in the direction perpendicular to the membrane surface. this layer has been described by a liquid crystal-like model (marčelja and radić, ) with water polarization playing a role of the order parameter. this approach successfully treated the hydration repulsion between apposing membranes (gruen and marčelja, ). extending, in the spirit of frank ( ), this liquid– crystalline model to description of deformations of splay and tilt of the hydration layer, one obtains a hamiltonian analogous to eq. , where the elastic coefficients account for the interactions between the polarized water molecules. this model predicts that, in the vicinity of the corner, the water polarization can avoid infinite splay by tilting with respect to the mem- brane surface, analogously to the deformation of the hydrocarbon tails we considered above. this allows avoiding a seemingly infinite energy of hydration layer in the corner, in full analogy with the energy of the hydrocarbon chains. within this model, the hydration layer undergoes deformations similar to those of the layer of the hydrocarbon chains, and its energy can be computed analogously to that of the lipid monolayer. at the current stage, we have no information available on the elastic moduli of the hydration layer, but we can draw some general conclusions. first, for deformation of simple bending of a lipid membrane, the layer of the hydrocarbon chains and the hydration layer undergo similar splay. therefore, the measured bending modulus includes contributions from the chains and from the polar head. according to the experimental results (leikin et al., ; fuller and rand, ), the values of the bending modulus practically do not depend on the type of polar heads. hence, the hydration of the heads contributes very little to the membrane splay elasticity. second, the elastic moduli of a layer scale as powers of its thickness (helfrich, ; hamm and kozlov, ). the thickness of a hydration layer is about ten times smaller than that of a lipid monolayer (rand and parsegian, ; leikin et al., ). hence, the elastic moduli of hydration layer are expected to give a less than % contribution to the total moduli of a lipid monolayer. we are grateful to leonid chernomordik for stimulating discussions, critical reading of the manuscript, and constructive suggestions. we thank david andelman, samuel safran, and michael schick for helpful discus- sions. m. k. is grateful to the israel science foundation funded by the israel academy of science and humanities and the human frontier sci- ence program organization for the financial support. references basanez, g., f. m. goni, and a. alonso. . effect of single chain lipids on phospholipase c-promoted vesicle fusion. a test 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relationships between an influenza virus and neutralizing antibody. virology. : – . thomas, t. . concepts from tensor analysis and differential geom- etry. vol. . academic press, inc., turner, d. c., and s. m. gruner. . x-ray reconstitution of the inverted hexagonal (hii) phase in lipid–water system. biochemistry. : – . walter, a., p. l. yeagle, and d. p. siegel. . diacylglycerol and hexadecane increase divalent cation-induced lipid mixing rates between phosphatidylserine large unilamellar vesicles. biophys. j. : – . weaver, j. c., and r. a. mintzer. . decreased bilayer stability due to transmembrane potentials. phys. lett. a: – . winterhalter, m., and w. helfrich. . effect of surface charge on the curvature elasticity of membranes. j. phys. chem. us. : – . stalk model of membrane fusion biophysical journal ( ) – 	stalk model of membrane fusion: solution of energy crisis 	introduction 	energy crisis of the stalk model 	criterion for energy of fusion intermediate 	energies predicted by the previous versions of the stalk model 	challenge for the present research 	structure of fusion stalk 	elastic model for stalk intermediate 	monolayer shape and deformations 	elastic energy 	energy of splay 	energy of tilt 	main equations 	energy and shape of stalk: results 	symmetric membranes 	stalk energy 	stalk configuration 	effects of spontaneous splay 	asymmetric membranes 	discussion 	comparison with previous models 	effects of different lipids 	effects of different monolayers 	effects of stalk dimensions 	assumptions of the model 	conclusions 	acknowledgement 	appendix adetailed form of equations andboundary conditions 	aim of analysis 	outline of analysis 	appendix bgeometrical relationships 	expression for splay 	relationship between the tangential angles of the monolayers and the bilayer midplane 	appendix cqualitative consideration of effects ofhydration forces 	references type of the paper (article nanomaterials , , . https://doi.org/ . /nano www.mdpi.com/journal/nanomaterials editorial nanocomposites for environmental and energy applications pei sean goh and ahmad fauzi ismail * advanced membrane technology research centre, school of chemical and energy engineering, universiti teknologi malaysia, johor bahru, malaysia; peisean@petroleum.utm.my * correspondence: afauzi@utm.my global environmental and energy issues are the two major challenges of the st cen- tury. climate change and the energy crisis have urgently called for the establishment of sustainable and innovative solutions to tackle these issues. among the many established strategies, the emergence of functional nanocomposites as potential tools to address envi- ronmental and energy-related issues has attracted wide attention in both laboratory re- search and industry applications. the synergistic effects concertedly contributed by a broad range of nanomaterials and their host materials have rendered unprecedented ad- vantages over the conventionally used materials. with the astonishing chemical and phys- ical properties exhibited by various nanocomposites, their potentials have been unlocked in many practical applications. nanocomposites are also particularly interesting in offer- ing sustainable solutions to curb global challenges related to environmental issues and energy shortages. this special issue, themed “nanocomposites for environmental and energy appli- cations”, gathers material scientists and engineers working in this realm to look into var- ious aspects associated to the development of the state-of-the-art nanocomposites dedi- cated for environmental and energy applications. a collection of research articles and re- views, with special attentions focused on the synthesis, design, optimization and applica- tions of novel nanocomposites has been compiled in this special issue. the nine contribu- tions (seven research articles and two reviews), look into the recent advancement and fu- ture trends related to the development of nanocomposites carbon-based nanocomposites are an important class of functional nanomaterials for the remediation of environmental issues and the development of energy-related devices. sun et al. engineered the dimensional interface of nanocomposite composed of bivo and reduced graphene oxide (rgo) [ ]. bivo and rgo of different dimensions (od, d and d) were synthesized and coupled to form a heterojunction semiconductor. it was ob- served that d– d chemical coupling of bivo and rgo exhibited the highest visible light activated photocatalytic activity toward the degradation of acetaminophen. the findings highlighted the importance of dimensional factors in the design of heterojunction photo- catalysts. lee et al. prepared mesoporous-rich activated polymer-based hard carbon to be used as electrodes in electrical double-layer capacitors [ ]. the optimization of textural properties such as pore size and pore distributions was performed by altering the steam activation conditions to achieve the optimal electrochemical capacity. cho demonstrated a facile method to synthesize low crystalline moo /carbon composite microspheres on a large scale [ ]. using a one-step spray pyrolysis technique, the moo nanocrystals were evenly distributed within the amorphous carbon matrix. the resultant moo /carbon com- posite microspheres achieved higher li-ion storage compared to moo owing to their greater high structural stability and electrical conductivity. the removal of heavy metals from wastewater using through adsorption and elec- trochemistry approaches has been investigated. tan et al. reported an enhanced sludge treatment to remove cu (ii) ions followed by the application of the copper-doped porous materials as supercapacitor electrode materials [ ]. the important aspects such as cu (ii) ion removal efficiency, specific capacity and cycling stability were evaluated. silica-coated citation: goh, p.s.; ismail, a.f. nanocomposites for environmental and energy applications. nanomaterials , , . https://doi.org/ . /nano received: january accepted: january published: january publisher’s note: mdpi stays neu- tral with regard to jurisdictional claims in published maps and insti- tutional affiliations. copyright: © by the authors. li- censee mdpi, basel, switzerland. this article is an open access article distributed under the terms and con- ditions of the creative commons at- tribution (cc by) license (http://crea- tivecommons.org/licenses/by/ . /). nanomaterials , , of magnetic nanoparticles that were chemically functionalized with amino-rich polyeth- yleneimine (bpei) have been developed by plohl et al. and used as nanoadsorbents for cu (ii) ion removal [ ]. the roles of bpei in enhancing the performance of nanoadsorbents were discussed. the reusability and simple recycling of the nanoadsorbents were high- lighted as the main features for practical applications for the treatment of heavy metal- contaminated sludge, sing polystyrene colloidal particles and go as sacrificial template and reinforcing filler, respectively. pan et al. prepared an aerogel consisting of porous calcium alginate and go [ ]. the nanocomposite exhibited high adsorption capacity to- wards pb (ii), cu (ii) and cd (ii) ions through ion exchange and chemical coordination mechanisms. linh et al. incorporated titania nanoparticles (tio ) into the d crossed re- gion of stacked plasmonic ag nanowires to enhance the photocatalytic activities [ ]. in this nanocomposite, ag nanowire contributed strong localized surface plasmon resonance excitation while the ag nanowires–tio interface rendered efficient hot electron transfer. the synergistic effects endowed the hybrid material with high photocatalytic performance across the ultraviolet and visible light spectral regions. the two review articles compiled in this special issue were contributed by subrama- niam et al. [ ] and tu et al. [ ], respectively. the former provided insights into the roles of nanomaterials in established and emerging technologies for hazardous heavy metal re- moval. the interesting features of nanomaterials and their hybrids as well as the synthesis techniques and removal principles are discussed in this review. different heavy metal re- moval mechanisms, covering adsorption, filtration and oxidation using novel nanocom- posites are presented. the second mini review looks into various in situ synthesis ap- proaches for si@c materials used for lithium ion batteries. with the increasing acceptance of si@c materials for the development of lithium ion batteries due to their excellent lith- ium ion intercalation capacity and cyclic stability, this review presents the current pro- gresses in the preparation and future research directions of si@c materials. the diverse contributions from these nine articles have witnessed the roles and im- portance of nanocomposites for environmental and energy applications. the versatilities of nanocomposites in addressing pollution and energy shortage issues have been evi- denced. these contributions have addressed some of the important fundamental ques- tions and shed light on the better understanding of the natures of the newly developed nanocomposite materials. it is hoped that this special issue could provide some useful guidelines for the future development of nanocomposites for environmental and energy applications. author contributions: p.s.g. and a.f.i. contributed to the planning, drafting and writing of the editorial. both authors have read and agreed to the published version of the manuscript. institutional review board statement: not applicable. informed consent statement: not applicable. data availability statement: not applicable. conflicts of interest: the authors declare no conflict of interest. references . sun, j.; wang, c.; shen, t.; song, h.; li, d.; zhao, r.; wang, x. engineering the dimensional interface of bivo - d reduced graphene oxide (rgo) nanocomposite for enhanced visible light photocatalytic performance. nanomaterials , , . . lee, h.m.; an, k.h.; park, s.j.; kim, b.j. mesopore-rich activated carbons for electrical double-layer capacitors by optimal acti- vation condition. nanomaterials , , . . cho, j.s. large scale process for low crystalline moo -carbon composite microspheres prepared by one-step spray pyrolysis for anodes in lithium-ion batteries. nanomaterials , , . . tan, z.; yu, f.; liu, l.; jia, x.; lv, y.; chen, l.; xu, y.; shi, y.; guo, x. cu-doped porous carbon derived from heavy metal- contaminated sewage sludge for high-performance supercapacitor electrode materials. nanomaterials , , . . plohl, o.; finšgar, m.; gyergyek, s.; ajdnik, u.; ban, i.; zemljič, l.f. efficient copper removal from an aqueous anvironment using a novel and hybrid nanoadsorbent based on derived-polyethyleneimine linked to silica magnetic nanocomposites. nano- materials , , . nanomaterials , , of . pan, l.; wang, z.; yang, q.; huang, r. efficient removal of lead, copper and cadmium ions from water by a porous calcium alginate/graphene oxide composite aerogel. nanomaterials , , . . linh, v.t.n.; xiao, x.; jung, h.s.; giannini, v.; maier, s.a.; kim, d.h.; lee, y.i.; park, s.g. compact integration of tio nano- particles into the cross-points of d vertically stacked ag nanowires for plasmon-enhanced photocatalysis. nanomaterials , , . . subramaniam, m.n.; goh, p.s.; lau, w.j.; ismail, a.f. the roles of nanomaterials in conventional and emerging technologies for heavy metal removal: a state-of-the-art review. nanomaterials , , . . tu, w.; bai, z.; deng, z.; zhang, h.; tang, h. in-situ synthesized si@c materials for the lithium ion battery: a mini review. nanomaterials , , . energies article design of an emergency energy system for a city assisted by renewable energy, case study: latakia, syria ghaeth fandi ,* , vladimír krepl , ibrahim ahmad , famous o. igbinovia , tatiana ivanova , soliman fandie , , zdenek muller and josef tlusty , department of sustainable technologies, faculty of tropical agrisciences, czech university of life sciences prague, kamýcká / , prague, czech republic; krepl@ftz.czu.cz (v.k.); ivanova@ftz.czu.cz (t.i.) department of electrical power engineering, faculty of electrical engineering, czech technical university in prague, technická , prague, czech republic; ahmadibr@fel.cvut.cz (i.a.); igbinfam@fel.cvut.cz (f.o.i.); zdenek.muller@fel.cvut.cz (z.m.) chercheur associé au laboratoire icar, umr , cnrs, université lumière lyon , ens de lyon, , parvis rené descartes bp , cedex , lyon, france; soliman.fandie@gmail.com chercheur associé au centre max weber umr , projet jadn, institut des systèmes complexes, université lumière lyon , avenue pierre-mendès-france, bron, france department of health care disciplines and population protection, faculty of biomedical engineering, czech technical university in prague, sportovců , kladno, czech republic; tlusty@fbmi.cvut.cz * correspondence: fandi@ftz.czu.cz; tel.: + - - - received: october ; accepted: november ; published: november ����������������� abstract: electrical energy is one of the most important daily needs. shortage of energy can be very dangerous for any society. this can affect the standard of living and quality of life of the people and even endanger the lives of those in hospitals, and so forth. developed countries do not face such risks in general because they have well organized electrical systems and high energy security. the developing countries are faced daily with electric system collapses, especially in the case of wars, where many parts of the electrical grid in the country can be damaged and fuel transmission lines for generators cut off. urban areas in developing countries should have a strategic plan to deal with any unexpected occurrence of energy shortages using any available renewable energy sources. city of latakia is located in the region which has been suffering from the consequences of war for more than six years. the fact that a high number of migrants from other cities have come to latakia along with a lack of fuel makes the energy shortage in the city worse. an emergency system could use the cheapest available renewable energy sources in addition to few big portable generators to provide an acceptable energy supply for the most needed requirements of daily life. keywords: energy shortage; emergency system; renewable energy; crisis; lack of fuel; urban areas . introduction the discovery of electricity was one of the most important things which moved civilization on to the level it is at present. getting a continuous and stable electric-power supply is one of the most important needs of human existence in the modern age, especially in cities where daily human activities are high both during the day and night hours [ ]. our high dependence on electricity in modern life in all sectors such as health, education, industry, business, communication, transport, food, . . . etc. makes long-term interruption in electricity supply equivalent to a disaster in modern life. therefore, any interruption to electricity supply for long hours significantly affects social economic energies , , ; doi: . /en www.mdpi.com/journal/energies http://www.mdpi.com/journal/energies http://www.mdpi.com https://orcid.org/ - - - https://orcid.org/ - - - http://dx.doi.org/ . /en http://www.mdpi.com/journal/energies http://www.mdpi.com/ - / / / ?type=check_update&version= energies , , of life, causes financial loss, negatively affects a nation’s economy, decrease the gross domestic product (gdp), retards development and daily life activities [ – ]. using electrical energy in the cities does not result in any emissions because power plants are usually located far from the cities so that their effects on human health and the environment in cities is reduced to the barest minimum. but due to poverty and weak infrastructure in developing countries, old ways of heating or cooking such as diesel and wood-burning are being used, most especially in the suburbs of cities. using such methods is very harmful to people’s health and the surrounding environment since they emit a lot of emissions [ , ]. in the same way, energy stored in fossil fuels that is released by human activity causes environmental pollution. furthermore, fossil fuel energy resources are exhaustible and alternatives will be needed in the near future [ ]. the extensive exploitation of renewable energy sources in cities has become an essential and practical strategy for fostering sustainable development [ ]. renewable energy sources such as solar, wind and biomass energy has become an essential part of the modern grid owing to the fact that renewable energy resources are clean and cannot be depleted; other reasons are that this reduces global warming, that there are limited levels of fossil fuel in the world and that diversification of energy sources achieves high levels of energy security, in addition to improving voltage profile and power quality [ , – ]. a lot of developing countries are susceptible to armed conflicts, natural disasters, regional and international disputes, economic crises, wars . . . and so forth which can affect power supply and rapidly increase the population in some regions due to migration from the neighbouring areas. in such cases an energy crisis can force people to use all alternative solutions to continue their daily life, even the oldest ones. an energy crisis in itself and these alternative solutions for it can have considerable negative effects on health, environment, education . . . etc. most cities in the developing countries have renewable sources which have not yet been invested in, especially biomass and solar energy. renewables can play a major role in mitigating an energy crisis especially in the remote areas of developing countries. considerable research has been done on the ability of renewable energy sources to solve the problems related to energy shortages. some of these projects have been proposed to mitigate electric-power crises in pakistan, china and bangladesh [ – ] and others are about to be implemented in africa and india [ – ]. in addition, renewable energy sources, together with the use of new eco-sustainable systems with low energy consumption [ , ] and new building technologies that use the new generation of low-cost smart-windows [ ], could be associated with local energy sources that can play an important role in the emergency system for any city or country but we also need a stable source of energy. continuous electricity supply enhances energy security, as energy security is a very important aspects of the energy plans of countries, mostly in situations where it is essential to have many sources of energy supply and to also have alternative sources of power in case of armed conflicts, natural disasters and so forth. power shortages and climate change are two great problems today. for this reason, the power sector must get rid of carbon emitting plants to create a pollution-free environment [ ]. it is hoped that renewable energy sources will help to reduce energy crises and prevent further climate change. renewable energy is one of the fundamental resources needed to help achieve the social, economic and environmental goals of mankind [ – ]. access to clean energy is essential for well-being, poverty reduction and the sustainable development of cities [ ]. these resources, in combination with several large portable power plants could be very effective in facing crises. energy security plans can be locally or centrally organized. local plans may be more efficient because each municipality can adopt a strategy according to its geographical location and the available energy sources. as result of the above, designing and implementing an emergency energy system is highly important for every city in the developing countries. in this paper, the syrian city, latakia is discussed as a case study of a city which has faced an unexpected energy crisis and its related consequences. the methodology adopted in the study and the data sources used for the analysis are also discussed in order to present the energy crisis effects energies , , of on urban areas and to show the importance of emergency energy systems. the data presented in this article has been collected by the authors and several volunteers. . methodology designing the emergency energy system and figuring out its capacity depend on two important factors which can arise when any city, in particular, faces an unexpected situation. these two factors are: . energy shortage (electricity): we can consider emergency levels according to the electricity cut off hours per day as shown in table . table . emergency levels and the corresponded electricity cut off hours. emergency level cut off hours per day for our methodology, we will assume an average case where rationing hours are daily, corresponding to emergency level , which implies a % decrease in the energy supply; we will also consider the expected demand for energy for this city in the future over the next years, where the total system will be updated every years. . migration: where in case of war or natural disasters, people migrate to other safe cities or areas and this causes an increase in residential energy consumption. we will consider emergency levels according to the population increase percentage as table shows: table . emergency levels and the corresponded population increase. emergency level population increase % . % % . % % here we will also consider the average case where the percentage of population increase is % corresponding to emergency level . any expected increase in the demand for energy due to the native population increases will not be considered because they are included in the previous factor. using these two factors we can define an emergency energy function according to the following equation ( ): eem = . [et( + eex %)] + . eres ( ) where: eem: emergency energy. et : total energy demand for the city in year. eex %: the percentage of expected energy demand for the next years. eres: residential energy demand in the city. energies , , of this emergency energy will come from different sources: . power plants: if there is a power plant close to the city and the fuel supply for this plant is secure and stable. . installed renewable sources: if any renewable sources are installed in city and the expected energy can be produced from them. . uninstalled renewable energy: the cheapest and most available renewable energy sources in the city which could be shared to solve the energy shortage problem. . portable generators energy: these generators can share the load with the previous sources whenever energy produced from renewable sources can-not be expected or is not stable, as we have to use alternative stable sources of electricity when renewable energy sources supply a city alone. these portable generators could be such as are used for industrial and commercial activities inside and outside the city and when any unexpected situation arises, they can be moved to residential areas where special rooms and filters should be used to reduce the noise and pollution inevitable with them. the emergency energy produced can be as shown in the following equation ( ): eem = ep + ere + ere + eg ( ) where: ep: energy supplied from the power plant in one year (known). eren : energy supplied from installed renewable sources in one year (known). eren : expected energy produced from renewable sources which can be installed in one year (unknown). eg: expected energy produced from generators which can be installed in one year (unknown). the needed energy can be as in the following equation ( ): en = eem − ere − ep ( ) now we have to calculate eren and eg. here we can consider two kinds of sources; the first is stable sources and the second is unstable sources, where the relationship between them can be formulated according to the following equation ( ): eem = es + eus ( ) . stable sources: which include power plants and portable generators can give stable power for all day and which we can describe in the following equation ( ): es = ep + eg ( ) . unstable sources: which include the installed and expected installed renewable sources; such sources are not stable sources and are related to the weather in general and we can describe them as in the following equation ( ): eus = ere + ere ( ) energies , , of in our emergency system we will depend on both these, where we will consider the following mathematical relations ( ) and ( ): es ≥ . eem ( ) eus ≤ . eem ( ) where the unstable source consists of renewable energy units. in some cities it could be very hard to produce half of the emergency energy from renewable sources. in addition, the stable source should provide at least half of the emergency energy, because a stable power source is very important for some serious sectors in every city. therefore, the required energy from the generators could be calculated as in the following equation ( ): eg = es − ep ( ) and the required energy from the renewable sources will be according to the next equation ( ): ere = eus − ere ( ) we can use the following algorithm to express the methodology and how we can get the required values as shown in figure . and in figure you can see matlab simulink model for the calculations of the methodology. energies , , x for peer review of 𝐸 = 𝐸 − 𝐸 ( ) we can use the following algorithm to express the methodology and how we can get the required values as shown in figure . and in figure you can see matlab simulink model for the calculations of the methodology. start get values of get values of calculate calculate calculate regn eee += end eem= . [et( +eex%)]+ . eres et ,eex% and eres ere ,ep and available ere eg=eem -(ere +ere +ep) figure . proposed algorithm for the emergency system. figure . proposed algorithm for the emergency system. energies , , of energies , , x for peer review of figure . matlab simulink model for the proposed methodology. . case study: latakia city, syria . . the effects of the war on syria as the consequence of the occurring syrian civil war, the whole region is unstable since . long lasting conflict remains because of the fragmented impact of many groups, including radical islam militias, and so forth... the syrian government and its service institutions, in addition to the civil people have faced many pressures and changes in many sectors. we mention that the presenting data from latakia and syria came from views, surveys, follow ups and contact with the responsible governmental institutions during the period – . . . . the social sector (especially the family) we not that spread of divorce, widows, orphans, disabled children because of losing body-parts due to injuries suffered because of the war, child labour, as a result of destitution, widespread increases in need and poverty, psychological and sexual violence against women and children ... and so forth. . . . the educational sector a large number of schools have stopped functioning and staff are out of work because of the destruction they have suffered in addition to the external migration and internal migration which forced hundreds of thousands of children to leave their schools, estimated at million children, thus increasing the illiteracy rate among children in syria after , where, before this date, illiteracy was almost non-existent, as the percentage of children enrolled in basic education at the beginning of the academic year was % ,declining in to less than %. figure . matlab simulink model for the proposed methodology. . case study: latakia city, syria . . the effects of the war on syria as the consequence of the occurring syrian civil war, the whole region is unstable since . long lasting conflict remains because of the fragmented impact of many groups, including radical islam militias, and so forth... the syrian government and its service institutions, in addition to the civil people have faced many pressures and changes in many sectors. we mention that the presenting data from latakia and syria came from views, surveys, follow ups and contact with the responsible governmental institutions during the period – . . . . the social sector (especially the family) we not that spread of divorce, widows, orphans, disabled children because of losing body-parts due to injuries suffered because of the war, child labour, as a result of destitution, widespread increases in need and poverty, psychological and sexual violence against women and children . . . and so forth. . . . the educational sector a large number of schools have stopped functioning and staff are out of work because of the destruction they have suffered in addition to the external migration and internal migration which forced hundreds of thousands of children to leave their schools, estimated at million children, thus increasing the illiteracy rate among children in syria after , where, before this date, illiteracy was almost non-existent, as the percentage of children enrolled in basic education at the beginning of the academic year was %, declining in to less than %. energies , , of . . . the economic sector we note increases in poverty, weakening purchasing power due to rising prices and increase unemployment. . . . the security sector we note a lack or loss of security and safety in most cities. . . . the service sector we note the inability of state institutions to provide the necessary services to citizens as a result of the pressures imposed by the war, especially in the field of providing the necessary oil derivatives for daily life, in addition to an electrical energy shortage which has caused many to use alternative solutions which are nonetheless unable to compensate for shortfall in covering electricity demand while contributing to a large extent to increased pollution of the environment, with significant repercussions for public health. . . . the demographic sector a new demographic map has been established that has affected the whole of syrian geography, especially the syrian regions and cities which are considered as safer than others, due to the absence of islamic groups. this new demographic map has been formed due to the growth of two types of migration: external and internal where the internal one was to the safe areas and cities of syria (damascus city, tartus city and latakia city). the latakia portion from that migration was the largest compared to other cities when compared to its population and geographical area. although there are no accurate statistical studies of the internal migration population, the estimated numbers indicate that one million inhabitants have reached the centre of latakia governate and its regions and villages. in our study we will study the energy problem and especially electricity. . . an overview of the electricity system and energy sources in latakia before the war the supply of electricity and energy in latakia before the war in was very effective where electricity was available / [ ] and was used in all industrial, commercial, agricultural and residential sectors. energy sources used was typically diesel or electricity for heating and gas for cooking. latakia city gets electricity through three / kv distribution stations which are connected to the national power system which run on various sources as shown in figure [ ] where syria depends on fossil fuels especially fuel and gas to get electricity and some renewable energy sources such as hydro energy and very small applications of solar and wind energy. energies , , x for peer review of . . . the economic sector we note increases in poverty, weakening purchasing power due to rising prices and increase unemployment. . . . the security sector we note a lack or loss of security and safety in most cities. . . . the service sector we note the inability of state institutions to provide the necessary services to citizens as a result of the pressures imposed by the war, especially in the field of providing the necessary oil derivatives for daily life, in addition to an electrical energy shortage which has caused many to use alternative solutions which are nonetheless unable to compensate for shortfall in covering electricity demand while contributing to a large extent to increased pollution of the environment, with significant repercussions for public health. . . . the demographic sector a new demographic map has been established that has affected the whole of syrian geography, especially the syrian regions and cities which are considered as safer than others, due to the absence of islamic groups. this new demographic map has been formed due to the growth of two types of migration: external and internal where the internal one was to the safe areas and cities of syria (damascus city, tartus city and latakia city). the latakia portion from that migration was the largest compared to other cities when compared to its population and geographical area. although there are no accurate statistical studies of the internal migration population, the estimated numbers indicate that one million inhabitants have reached the centre of latakia governate and its regions and villages. in our study we will study the energy problem and especially electricity. . . an overview of the electricity system and energy sources in latakia before the war the supply of electricity and energy in latakia before the war in was very effective where electricity was available / [ ] and was used in all industrial, commercial, agricultural and residential sectors. energy sources used was typically diesel or electricity for heating and gas for cooking. latakia city gets electricity through three / kv distribution stations which are connected to the national power system which run on various sources as shown in figure [ ] where syria depends on fossil fuels especially fuel and gas to get electricity and some renewable energy sources such as hydro energy and very small applications of solar and wind energy. figure . power plant in syria. figure . power plant in syria. energies , , of most of these energy sources were available locally from oil and gas wells where oil production was , barrels per day and gas production was million m per day in . syria also has two refineries which produce diesel, fuel and other products. . . the energy shortage in latakia during the war we can summarize the energy situation from till with the following: . . . rationing hours since the start of the war in syria in electricity hours started to decrease using a power rationing system where rationing hours were as shown in figure from [ ] where we can notice an increase in rationing hours from h in up to h in . energies , , x for peer review of most of these energy sources were available locally from oil and gas wells where oil production was , barrels per day and gas production was million m per day in . syria also has two refineries which produce diesel, fuel and other products. . . the energy shortage in latakia during the war we can summarize the energy situation from till with the following: . . . rationing hours since the start of the war in syria in electricity hours started to decrease using a power rationing system where rationing hours were as shown in figure from [ ] where we can notice an increase in rationing hours from h in up to h in . figure . electricity supply during years – . . . . peak power demand figure [ ] shows how peak demand has changed in latakia where we can notice gradual increase from till and the highest increase was in where it is about % for to many reasons especially-migration from other parts of syria to latakia city. also, we can notice that the increase in is less than as some families came back to aleppo and homs. figure . peak power demand – . figure . electricity supply during years – . . . . peak power demand figure [ ] shows how peak demand has changed in latakia where we can notice gradual increase from till and the highest increase was in where it is about % for to many reasons especially-migration from other parts of syria to latakia city. also, we can notice that the increase in is less than as some families came back to aleppo and homs. energies , , x for peer review of most of these energy sources were available locally from oil and gas wells where oil production was , barrels per day and gas production was million m per day in . syria also has two refineries which produce diesel, fuel and other products. . . the energy shortage in latakia during the war we can summarize the energy situation from till with the following: . . . rationing hours since the start of the war in syria in electricity hours started to decrease using a power rationing system where rationing hours were as shown in figure from [ ] where we can notice an increase in rationing hours from h in up to h in . figure . electricity supply during years – . . . . peak power demand figure [ ] shows how peak demand has changed in latakia where we can notice gradual increase from till and the highest increase was in where it is about % for to many reasons especially-migration from other parts of syria to latakia city. also, we can notice that the increase in is less than as some families came back to aleppo and homs. figure . peak power demand – . figure . peak power demand – . energies , , of . . . peak power demand concerning demand for electric power there are two conditions: . with power rationing figure [ ] shows the demand in this condition where the energy demand decreases slightly but in general we can say that it does not change a lot after because the available energy sources were limited and that expound the reason of rationing hours increase. energies , , x for peer review of . . . peak power demand concerning demand for electric power there are two conditions: . with power rationing figure [ ] shows the demand in this condition where the energy demand decreases slightly but in general we can say that it does not change a lot after because the available energy sources were limited and that expound the reason of rationing hours increase. figure . energy demand – . . without power rationing where the syrian ministry of electricity gave an approximate value for the demand for electric power every year. figure [ ] shows total energy demand without power rationing and the relevant shortage values where we can notice that the energy demand without rationing is much bigger than it is with rationing and that demand is seen as increasing slightly after . regarding the energy shortage the figure shows how it increased rapidly between and ; the changes then become smaller because most people migrated to latakia city during the period to . (a) (b) figure . (a) total energy demand (without rationing) – ; (b) energy shortage – . . . . energy resources oil production decreased to , barrels per day and natural gas to . million m per day. figure . energy demand – . . without power rationing where the syrian ministry of electricity gave an approximate value for the demand for electric power every year. figure [ ] shows total energy demand without power rationing and the relevant shortage values where we can notice that the energy demand without rationing is much bigger than it is with rationing and that demand is seen as increasing slightly after . regarding the energy shortage the figure shows how it increased rapidly between and ; the changes then become smaller because most people migrated to latakia city during the period to . energies , , x for peer review of . . . peak power demand concerning demand for electric power there are two conditions: . with power rationing figure [ ] shows the demand in this condition where the energy demand decreases slightly but in general we can say that it does not change a lot after because the available energy sources were limited and that expound the reason of rationing hours increase. figure . energy demand – . . without power rationing where the syrian ministry of electricity gave an approximate value for the demand for electric power every year. figure [ ] shows total energy demand without power rationing and the relevant shortage values where we can notice that the energy demand without rationing is much bigger than it is with rationing and that demand is seen as increasing slightly after . regarding the energy shortage the figure shows how it increased rapidly between and ; the changes then become smaller because most people migrated to latakia city during the period to . (a) (b) figure . (a) total energy demand (without rationing) – ; (b) energy shortage – . . . . energy resources oil production decreased to , barrels per day and natural gas to . million m per day. figure . (a) total energy demand (without rationing) – ; (b) energy shortage – . . . . energy resources oil production decreased to , barrels per day and natural gas to . million m per day. energies , , of . . causes of the energy shortage . the appearance of isis in syria has made people abandon their houses and go to safe areas and latakia city is one of the safest cities in syria as we mentioned before. and this has caused an increase in the population of latakia city as shown in table and figure according to estimates, there being no formal statistics for the population. the numbers and percentages shown in the table relate to the population change only in the city centre of latakia because most of the migrants live in the centre of the city in its various neighbourhoods. the change in the percentage in was a result of the liberation of aleppo and homs cities from radical islamic groups, which contributed to the return of people from those cities to their homes. . significant decreases in oil and gas production were because isis captured most oil and gas wells in homs and deir alzor as shown in figure . . the destruction of power plants and transmission lines by isis and other “terrorists groups” such as in homs, aleppo and hama reduced the ability to generate energy and to transmit it between governates. figure shows the power plants in syria. table . population changes in latakia and causes of migration – . year population change percentage % cause of the increase , - no migration , . % migration from idlib, hama and homs , . % migration from aleppo , . % migration from aleppo and latakia rural , , . % migration from aleppo and latakia rural , , . % going back to aleppo and homs energies , , x for peer review of . . causes of the energy shortage . the appearance of isis in syria has made people abandon their houses and go to safe areas and latakia city is one of the safest cities in syria as we mentioned before. and this has caused an increase in the population of latakia city as shown in table and figure according to estimates, there being no formal statistics for the population. the numbers and percentages shown in the table relate to the population change only in the city centre of latakia because most of the migrants live in the centre of the city in its various neighbourhoods. the change in the percentage in was a result of the liberation of aleppo and homs cities from radical islamic groups, which contributed to the return of people from those cities to their homes. . significant decreases in oil and gas production were because isis captured most oil and gas wells in homs and deir alzor as shown in figure . . the destruction of power plants and transmission lines by isis and other “terrorists groups” such as in homs, aleppo and hama reduced the ability to generate energy and to transmit it between governates. figure shows the power plants in syria. table . population changes in latakia and causes of migration – . year population change percentage % cause of the increase , - no migration , . % migration from idlib, hama and homs , . % migration from aleppo , . % migration from aleppo and latakia rural , , . % migration from aleppo and latakia rural , , . % going back to aleppo and homs figure . population changes in latakia – . figure below shows the migration tracks of people from aleppo, hama, idlib and latakia rural to latakia city where we can notice the high number of population who came to latakia city and the locations of oil and gas wells which were located in the areas in the control areas of isis in addition to power plants. figure . population changes in latakia – . figure below shows the migration tracks of people from aleppo, hama, idlib and latakia rural to latakia city where we can notice the high number of population who came to latakia city and the locations of oil and gas wells which were located in the areas in the control areas of isis in addition to power plants. energies , , of energies , , x for peer review of latakia tartus idlib aleppo homs hama damascus alsuwayda daraa alraqqah a b c d e alhasakah dayr alzawer oil and gas wel power plants immigration to latakia immigration from latakia figure . migration tracks, oil and gas wells and power plants. . . the current solutions to the shortage since people have started using utilities to face energy shortages: . diesel and gasoline generators: with different power capacities from kw up to over kw. figure shows the number of generators in use from till where a rapid increase can be seen during the period to because of the big increase of population in this period due to migration as mentioned before. also, we can notice that the highest increase where in the generators with small capacities due to the daily life needs of families such as lighting or some electronic devices. figure . number of portable generators – . figure . migration tracks, oil and gas wells and power plants. . . the current solutions to the shortage since people have started using utilities to face energy shortages: . diesel and gasoline generators: with different power capacities from kw up to over kw. figure shows the number of generators in use from till where a rapid increase can be seen during the period to because of the big increase of population in this period due to migration as mentioned before. also, we can notice that the highest increase where in the generators with small capacities due to the daily life needs of families such as lighting or some electronic devices. energies , , x for peer review of latakia tartus idlib aleppo homs hama damascus alsuwayda daraa alraqqah a b c d e alhasakah dayr alzawer oil and gas wel power plants immigration to latakia immigration from latakia figure . migration tracks, oil and gas wells and power plants. . . the current solutions to the shortage since people have started using utilities to face energy shortages: . diesel and gasoline generators: with different power capacities from kw up to over kw. figure shows the number of generators in use from till where a rapid increase can be seen during the period to because of the big increase of population in this period due to migration as mentioned before. also, we can notice that the highest increase where in the generators with small capacities due to the daily life needs of families such as lighting or some electronic devices. figure . number of portable generators – . figure . number of portable generators – . energies , , of in figure we can see old diesel generators deployment in the streets of latakia city with apparent oil leakage and significant production of harmful noise pollution and toxic exhaust gases. energies , , x for peer review of in figure we can see old diesel generators deployment in the streets of latakia city with apparent oil leakage and significant production of harmful noise pollution and toxic exhaust gases. figure . old portable generators in latakia’s streets. and the average power supplied by these generators for each year can be calculated according to the number of rationing hours as shown in figure using the following equation ( ): 𝐸 = (𝑃𝑚 · 𝑛 + 𝑃𝑚 · 𝑛 + ⋯ 𝑃𝑚 · 𝑛 ) · 𝐶 · ( ) where: e: the generated energy for each year. 𝑃𝑚 , 𝑃𝑚 … 𝑃𝑚 : the average power for each group of generators. 𝑛 , 𝑛 … 𝑛 : the number of generators for each group. 𝐶: the number of rationing hours for each year. : the number of days in a year. we have calculated the short-fall before considering the power generated from portable generators by adding the power generated from these generators to the short-fall so that the real short-fall is as shown in figure where the figure shows that the real short-fall in power is bigger. the generated energy from portable generators is about % of the real short-fall in general and that is make us understand how the energy crisis where bad in city especially if we know that a lot of people were using only batteries for lights during nights figure . old portable generators in latakia’s streets. and the average power supplied by these generators for each year can be calculated according to the number of rationing hours as shown in figure using the following equation ( ): e = (pm ·n + pm ·n + . . . pm ·n )·c· ( ) where: e: the generated energy for each year. pm , pm . . . pm : the average power for each group of generators. n , n . . . n : the number of generators for each group. c: the number of rationing hours for each year. : the number of days in a year. we have calculated the short-fall before considering the power generated from portable generators by adding the power generated from these generators to the short-fall so that the real short-fall is as shown in figure where the figure shows that the real short-fall in power is bigger. the generated energy from portable generators is about % of the real short-fall in general and that is make us understand how the energy crisis where bad in city especially if we know that a lot of people were using only batteries for lights during nights. energies , , of energies , , x for peer review of figure . portable generators energy contribution and total energy shortage – . . batteries: there are different capacities of – ah batteries where in general every home has or batteries with most of these batteries being of inferior types or recycled so that they have to change them every year or sometime after months. these batteries are used in general for lighting where they are connected to led lamps. they are also used to charge mobile phones and tv’s. figure shows how the batteries are used in homes. figure . installed batteries in homes in latakia city. . wood is used for heating in latakia suburbs and most of this wood comes from rural areas and forests in latakia where a lot of trees are being cut down and some forests have disappeared or semi disappeared. . . effects of the current solutions . . . health using such methods increases a number of diseases [ ] such as: . respiratory system diseases including asthma and bronchitis: where most of the generators are of inferior types and are installed in the streets, they emit a considerable amount of gas emissions such as carbon dioxide (co ), carbon monoxide (co) and nitrogen oxide (nox) … and so forth. wood combustion also emits a lot of gases especially (co) which is very harmful to babies, children and older people. . we see an increase in sight diseases because of led lights where most of these lights produce focused light which can be harmful for eyes or be weak when the battery is close to exhausted. figure . portable generators energy contribution and total energy shortage – . . batteries: there are different capacities of – ah batteries where in general every home has or batteries with most of these batteries being of inferior types or recycled so that they have to change them every year or sometime after months. these batteries are used in general for lighting where they are connected to led lamps. they are also used to charge mobile phones and tv’s. figure shows how the batteries are used in homes. energies , , x for peer review of figure . portable generators energy contribution and total energy shortage – . . batteries: there are different capacities of – ah batteries where in general every home has or batteries with most of these batteries being of inferior types or recycled so that they have to change them every year or sometime after months. these batteries are used in general for lighting where they are connected to led lamps. they are also used to charge mobile phones and tv’s. figure shows how the batteries are used in homes. figure . installed batteries in homes in latakia city. . wood is used for heating in latakia suburbs and most of this wood comes from rural areas and forests in latakia where a lot of trees are being cut down and some forests have disappeared or semi disappeared. . . effects of the current solutions . . . health using such methods increases a number of diseases [ ] such as: . respiratory system diseases including asthma and bronchitis: where most of the generators are of inferior types and are installed in the streets, they emit a considerable amount of gas emissions such as carbon dioxide (co ), carbon monoxide (co) and nitrogen oxide (nox) … and so forth. wood combustion also emits a lot of gases especially (co) which is very harmful to babies, children and older people. . we see an increase in sight diseases because of led lights where most of these lights produce focused light which can be harmful for eyes or be weak when the battery is close to exhausted. figure . installed batteries in homes in latakia city. . wood is used for heating in latakia suburbs and most of this wood comes from rural areas and forests in latakia where a lot of trees are being cut down and some forests have disappeared or semi disappeared. . . effects of the current solutions . . . health using such methods increases a number of diseases [ ] such as: . respiratory system diseases including asthma and bronchitis: where most of the generators are of inferior types and are installed in the streets, they emit a considerable amount of gas emissions such as carbon dioxide (co ), carbon monoxide (co) and nitrogen oxide (nox) . . . and so forth. wood combustion also emits a lot of gases especially (co) which is very harmful to babies, children and older people. . we see an increase in sight diseases because of led lights where most of these lights produce focused light which can be harmful for eyes or be weak when the battery is close to exhausted. energies , , of . likewise, for hearing diseases where most of the generators do not have good mufflers or do not have any at all which causes a lot of noise especially for people who work close to them and this can affect their hearing. . and other diseases related to the toxic chemicals and gas emissions from expired batteries where most of these are thrown randomly on open lands or into waterways. . . . environment using a lot of generators of inferior types, in addition to batteries and wood, can cause a lot of pollution in the city [ ] where the pollutants from each source are: . generator pollutants: carbon dioxide (co ), carbon monoxide (co), nitrogen oxide (nox), hydrocarbons (hc) and particulate matter (pm). . battery pollutants: improper or careless handling of waste batteries can result in the release of corrosive liquids and dissolved metals that are toxic to plants and animals. improper disposal of batteries in landfill sites can result in the release of toxic substances into groundwater and the environment. . wood pollutants: carbon monoxide (co), irritant compounds, polycyclic aromatic hydrocarbons (pahs), volatile organic compounds, dioxins and carbon monoxide (co). . . . education and social problems . increases in noise in buildings and streets have made concentration harder for the students [ ] in addition to the stress caused by such noise especially because most of these portable generators are cheap and poor quality and cause high noise levels. . additional difficulties in studying over prolonged periods arise from bad lightings because most of the lights used during the rationing hours are led lights, which are concentrated and strong at the beginning and very low after some time because of the cheap and poor quality of the batteries. . we note increases in the living costs for families which are already have financial problems. . . designing an emergency system we have made an overview of the electrical situation and energy crisis in latakia city in syria. now we will apply the previous methodology for latakia as if an emergency system had been applied in and we will see the advantages of such a system. the power demand in latakia in was et = , , gwh and the residential power demand was about % of that, so it was about eres = , , gwh. the expected increase in energy demand for the next years for latakia was about eex = %. therefore, according to equation ( ) the emergency energy would be eem = . gwh. this energy could be obtained with co-generators powered by gas oil, capable of supplying both electrical and thermal energy, typical hospital requests [ ]. these co-generators should be monitored with new “e-sensing” control systems in order to keep under check the presence of any pollutants dangerous to human health [ ]. now we will calculate the energy needed according to equation ( ): for ep: there is no power plant near latakia city therefore, ep = gwh. for ere : in latakia city there are only some solar applications such as solar panels in tishreen university also some installed panels on the communications tower in addition to some domestic solar applications and the estimated energy produced by them is about . gwh. therefore, the needed energy is en = . gwh. according to equations ( ) and ( ): es ≥ . gwh eus ≤ . gwh energies , , of . . . for unstable sources in latakia city there are only a limited number of solar panel applications such as the solar panels in tishreen university and also some panels installed on the communications tower in addition to some domestic solar applications with an estimated energy produce by these of about . gwh. biomass energy: there is a large area of landfill near latakia in al-bassa which receives about ton/day. therefore, if we build a power plant to produce electricity from this waste, the generated electrical energy according to [ – ] will be about mwh per day and . gwh. also, we have a high solar radiation in latakia. in latakia we have two choices to install solar panels: . on buildings rooves such as on schools, universities, residential buildings, . . . etc. as shown in table . table . area of building roofs in latakia city. buildings area (m ) schools , faculties and university buildings , government buildings , residential buildings , thus, the area would be s = , m . . on the unused lands around the city which cannot be used for agriculture or buildings. the area of these lands is about , m . so, the total area would be about , m according to photovoltaic geographical information system [ ], we have got figures and for latakia. in figure we can notice the location choosing and the optimal slope of the solar panels which is θ = ◦ . and in figure we got the average daily sum of global irradiation per square meter without taking into consideration the power losses g = hd = . kwh/m · day. and if we take losses into consideration the average daily sum of global irradiation will be: g = ed = . kwh/m · day energies , , x for peer review of in latakia city there are only a limited number of solar panel applications such as the solar panels in tishreen university and also some panels installed on the communications tower in addition to some domestic solar applications with an estimated energy produce by these of about . gwh. biomass energy: there is a large area of landfill near latakia in al-bassa which receives about ton/day. therefore, if we build a power plant to produce electricity from this waste, the generated electrical energy according to [ – ] will be about mwh per day and . gwh. also, we have a high solar radiation in latakia. in latakia we have two choices to install solar panels: . on buildings rooves such as on schools, universities, residential buildings, … etc. as shown in table . table . area of building roofs in latakia city. buildings area (m ) schools , faculties and university buildings , government buildings , residential buildings , thus, the area would be s = , m . on the unused lands around the city which cannot be used for agriculture or buildings. the area of these lands is about , m . so, the total area would be about , m according to photovoltaic geographical information system [ ], we have got figures and for latakia. in figure we can notice the location choosing and the optimal slope of the solar panels which is 𝜃 = °. and in figure we got the average daily sum of global irradiation per square meter without taking into consideration the power losses 𝐺 = 𝐻 = . kwh/m . day. and if we take losses into consideration the average daily sum of global irradiation will be: 𝐺 = 𝐸 = . kwh/m . day figure . photovoltaic geographical information system for latakia and optimal slope. figure . photovoltaic geographical information system for latakia and optimal slope. energies , , of energies , , x for peer review of figure . solar radiation data and electricity production in latakia. to calculate the electrical power which could be calculated from solar energy it will be used one solar panel with high power ( w) due to the big areas and big demand of electric power. therefore, we will calculate the needed area for each solar panel so we can calculate the total number of solar panels and electricity production. the calculations should be made on the december because that is when the sun will be lowest in the sky where the shadow will be the longest and solar altitude angle α. and it should be used suns azimuth angle ψ to know the sun’s relative direction along the local horizon. these angles could be calculated from [ ] where for latakia we got: α = . °·ψ = . ° to calculate the distance between the solar rows it should be calculate the high of the solar panel from the equation ( ): ℎ = 𝑥 · 𝑠𝑖𝑛 𝜃 ( ) where: x: length of the solar panel (m). 𝜃: optimal slope angle (degree). therefore, ℎ = . m. after that it will be calculated the maximum shadow length 𝐷 equation ( ): 𝐷′ = ℎ/𝑡𝑎𝑛 𝛼 ( ) therefore, 𝐷 = . m. then it could be calculating the distance between the solar rows 𝐷 (minimum array row spacing) from the equation ( ): 𝐷 = 𝐷′ · 𝑐𝑜𝑠 ( − 𝜓) ( ) therefore, 𝐷 = . m. so, the area for each solar panel is sum of the area which the solar panel covers on the roof and the area of its shadow according to equation ( ): 𝑆 = 𝑥 · 𝑐𝑜𝑠 (𝜃) · 𝑦 + 𝐷 · 𝑦 ( ) where: figure . solar radiation data and electricity production in latakia. to calculate the electrical power which could be calculated from solar energy it will be used one solar panel with high power ( w) due to the big areas and big demand of electric power. therefore, we will calculate the needed area for each solar panel so we can calculate the total number of solar panels and electricity production. the calculations should be made on the december because that is when the sun will be lowest in the sky where the shadow will be the longest and solar altitude angle α. and it should be used suns azimuth angle ψ to know the sun’s relative direction along the local horizon. these angles could be calculated from [ ] where for latakia we got: α = . ◦·ψ = . ◦ to calculate the distance between the solar rows it should be calculate the high of the solar panel from the equation ( ): h = x·sinθ ( ) where: x: length of the solar panel (m). θ: optimal slope angle (degree). therefore, h = . m. after that it will be calculated the maximum shadow length d′ equation ( ): d′ = h/tanα ( ) therefore, d′ = . m. then it could be calculating the distance between the solar rows d (minimum array row spacing) from the equation ( ): d = d′·cos( − ψ) ( ) therefore, d = . m. energies , , of so, the area for each solar panel is sum of the area which the solar panel covers on the roof and the area of its shadow according to equation ( ): s = x·cos(θ)·y + d·y ( ) where: y: width of the solar panel (m). therefore, s = . m . so, the number of solar panels which could be installed is calculated from equation ( ): n = s/s = , / . = , solar panel ( ) the generated energy from the selected solar panel is calculated using the equation ( ): em = a·η·g ( ) where: a: the solar panel area ( . m ). η : solar panel efficiency ( . %). g: average daily sum of global irradiation ( . kwh/m ·day). therefore, em = . kwh·day. so, the generated energy from all the solar panels for a year will be according to equation ( ): e = ·n·em ( ) therefore, e = . gwh. according to previous calculations, the total energy which could be generated from renewable sources is eus = . gwh per year. . . . for stable sources es = eem − eus = . gwh we have to install portable generators where the available portable generators before the war were only a few ones with small capacities so we can consider that eg = . therefore, the power of these generators should be pp = ep / = . mw. . . the advantages of the proposed emergency system if it was applied before the war . . . for the electricity situation we can find the effect of this system for each year since by dividing the total energy which could be generated by the emergency system by the total short-fall for each year as shown in figure . energies , , of energies , , x for peer review of where: y: width of the solar panel (m). therefore, 𝑆 = . m . so, the number of solar panels which could be installed is calculated from equation ( ): 𝑁 = 𝑆/𝑆 = , / . = , 𝑠𝑜𝑙𝑎𝑟 𝑝𝑎𝑛𝑒𝑙 ( ) the generated energy from the selected solar panel is calculated using the equation ( ): 𝐸𝑚 = 𝐴 · 𝜂 · 𝐺 ( ) where: a: the solar panel area ( . m ). 𝜂 ∶ solar panel efficiency ( . %). 𝐺: average daily sum of global irradiation ( . kwh/m ·day). therefore, 𝐸𝑚 = . kwh · day. so, the generated energy from all the solar panels for a year will be according to equation ( ): 𝐸 = · 𝑁 · 𝐸𝑚 ( ) therefore, 𝐸 = . gwh. according to previous calculations, the total energy which could be generated from renewable sources is 𝐸𝑢𝑠 = . gwh per year. . . . for stable sources 𝐸𝑠 = 𝐸𝑒𝑚 − 𝐸𝑢𝑠 = . gwh we have to install portable generators where the available portable generators before the war were only a few ones with small capacities so we can consider that 𝐸𝑔 = . therefore, the power of these generators should be 𝑃𝑝 = 𝐸𝑝 / = . mw. . . the advantages of the proposed emergency system if it was applied before the war . . . for the electricity situation we can find the effect of this system for each year since by dividing the total energy which could be generated by the emergency system by the total short-fall for each year as shown in figure . figure . emergency system contribution to energy shortage coverage – . figure . emergency system contribution to energy shortage coverage – . so, the proposed solution will compensate for the power generated from the generators because the total generated power from emergency system is . gwh per year and the highest generated power from generators was . gwh in in addition to reducing the rationing hours as shown in table . table . comparison of rationing hours with and without the emergency system. year rationing hours (without emergency system) rationing hours (without emergency system) min h min min . . . for the environment and health . forests: figure shows the forests which has been cut in latakia, where we can notice that the increase is gradual and it is not related to the energy shortage or demand because of many reasons. people move toward using wood because it is cheap also it is hard to control all the lands and forests to prevent this from happening. energies , , x for peer review of so, the proposed solution will compensate for the power generated from the generators because the total generated power from emergency system is . gwh per year and the highest generated power from generators was . gwh in in addition to reducing the rationing hours as shown in table . table . comparison of rationing hours with and without the emergency system. year rationing hours (without emergency system) rationing hours (without emergency system) min h min min . . . for the environment and health . forests: figure shows the forests which has been cut in latakia, where we can notice that the increase is gradual and it is not related to the energy shortage or demand because of many reasons. people move toward using wood because it is cheap also it is hard to control all the lands and forests to prevent this from happening. figure . cut area of forests in latakia rural – . cutting the trees will cause an increase in (co ) and a decrease in (o ), where according to reference [ , ] trees with a height of – dbh produce . kg (o )/year and urban whole tree carbon storage densities average . kg/m of tree cover per year where tree cover in latakia is about % on average. also, combustion of wood causes an increase in (co ) and a decrease in (o ) and according to [ ] the carbon concentration is about . – . % in subtropical/mediterranean species where each tree weighs about kg. therefore, cutting the trees and burning them will be very harmful to the environment. if the emergency system had been used in latakia city it would have been able to reduce the emissions which have occurred in the years as shown in figure . figure . cut area of forests in latakia rural – . energies , , of cutting the trees will cause an increase in (co ) and a decrease in (o ), where according to reference [ , ] trees with a height of – dbh produce . kg (o )/year and urban whole tree carbon storage densities average . kg/m of tree cover per year where tree cover in latakia is about % on average. also, combustion of wood causes an increase in (co ) and a decrease in (o ) and according to [ ] the carbon concentration is about . – . % in subtropical/mediterranean species where each tree weighs about kg. therefore, cutting the trees and burning them will be very harmful to the environment. if the emergency system had been used in latakia city it would have been able to reduce the emissions which have occurred in the years as shown in figure .energies , , x for peer review of figure . increase in (co ) and decrease in (o ) due to cutting the trees and the combustion of wood. . generators: according to [ ] the emissions from diesel generator sets are a mixture of gases primarily comprised of carbon monoxide (co), oxides of nitrogen (nox), unburned hydrocarbons (hc) and soot particles (particulate matter or pm). emission norms are specified based on the number of grams of these compounds present in diesel exhaust per kilowatt-hour of electricity generated. the emission limits reached of (nox) are up to . g/kwh, . g/kwh in the case of (hc), . g/kwh in the case of (co) and . g/kwh of (pm). figure shows the emissions from the portable generators which shows how these generators could be harmful for people’s health and the environment inside the city. thus, the reduced amounts of emissions during the years would be as shown in the figure. figure . emission from the portable generators – . . conclusions lack of planning of secure energy sources and depending on one source to generate electricity can lead to energy crises in the case of unexpected situations such as armed conflicts. renewable energy sources are secure because they can work as local energy sources so they can play a major role in the emergency system for any city or country but we need stable sources of energy too. this research could be used to design a local emergency system for any city depending on many factors such as population, energy demand, available renewables sources, and so forth, which will be very useful for energy security in any city or country. designing the emergency energy system has been figure . increase in (co ) and decrease in (o ) due to cutting the trees and the combustion of wood. . generators: according to [ ] the emissions from diesel generator sets are a mixture of gases primarily comprised of carbon monoxide (co), oxides of nitrogen (nox), unburned hydrocarbons (hc) and soot particles (particulate matter or pm). emission norms are specified based on the number of grams of these compounds present in diesel exhaust per kilowatt-hour of electricity generated. the emission limits reached of (nox) are up to . g/kwh, . g/kwh in the case of (hc), . g/kwh in the case of (co) and . g/kwh of (pm). figure shows the emissions from the portable generators which shows how these generators could be harmful for people’s health and the environment inside the city. thus, the reduced amounts of emissions during the years would be as shown in the figure. energies , , x for peer review of figure . increase in (co ) and decrease in (o ) due to cutting the trees and the combustion of wood. . generators: according to [ ] the emissions from diesel generator sets are a mixture of gases primarily comprised of carbon monoxide (co), oxides of nitrogen (nox), unburned hydrocarbons (hc) and soot particles (particulate matter or pm). emission norms are specified based on the number of grams of these compounds present in diesel exhaust per kilowatt-hour of electricity generated. the emission limits reached of (nox) are up to . g/kwh, . g/kwh in the case of (hc), . g/kwh in the case of (co) and . g/kwh of (pm). figure shows the emissions from the portable generators which shows how these generators could be harmful for people’s health and the environment inside the city. thus, the reduced amounts of emissions during the years would be as shown in the figure. figure . emission from the portable generators – . . conclusions lack of planning of secure energy sources and depending on one source to generate electricity can lead to energy crises in the case of unexpected situations such as armed conflicts. renewable energy sources are secure because they can work as local energy sources so they can play a major role in the emergency system for any city or country but we need stable sources of energy too. this research could be used to design a local emergency system for any city depending on many factors such as population, energy demand, available renewables sources, and so forth, which will be very useful for energy security in any city or country. designing the emergency energy system has been figure . emission from the portable generators – . energies , , of . conclusions lack of planning of secure energy sources and depending on one source to generate electricity can lead to energy crises in the case of unexpected situations such as armed conflicts. renewable energy sources are secure because they can work as local energy sources so they can play a major role in the emergency system for any city or country but we need stable sources of energy too. this research could be used to design a local emergency system for any city depending on many factors such as population, energy demand, available renewables sources, and so forth, which will be very useful for energy security in any city or country. designing the emergency energy system has been done according to points such as capacity of the system, future needs, expected threats on the system. in addition, to make sure that the system will be stable and able to provide the most needed requirements of the city by choosing more than half of the system as big portable generators. this research gives a guide for any city or governate all needed parameters to start designing emergency energy system. the case of latakia city is a real case so these data can be used as a basis for designing an emergency security system in the current world with insecure fuel lines, wars and disasters. this information and data could be used also as a reference for further studies regarding electricity and the environment in latakia or syria. author contributions: conceptualization, g.f., v.k., s.f., and i.a.; methodology, g.f.; software, g.f., and i.a.; validation, t.i. and v.k.; formal analysis, g.f., i.a., t.i., f.o.i., and z.m.; investigation, j.t., z.m., t.i., s.f., and v.k.; resources, g.f., v.k, s.f. and i.a.; writing-original draft preparation, g.f., i.a., v.k., f.o.i.; project administration, z.m., v.k., j.t., i.a., and g.f. funding: this research was supported by the “environmental and non-waste technologies for sustainable development of energy use and agriculture” grant number internal grant of culs fta prague and grant agency of the czech technical university in prague (grant no. sgs / /ohk / t/ ). acknowledgments: the financial support of the “environmental and non-waste technologies for sustainable development of energy use and agriculture” grant number internal grant of culs fta prague 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[crossref] © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . /ijht. sp http://dx.doi.org/ . /ijht. http://re.jrc.ec.europa.eu/pvgis/apps /pvest.php http://re.jrc.ec.europa.eu/pvgis/apps /pvest.php https://www.esrl.noaa.gov/gmd/grad/solcalc/ https://www.esrl.noaa.gov/gmd/grad/solcalc/ http://dx.doi.org/ . /j.envpol. . . http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /f http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	introduction 	methodology 	case study: latakia city, syria 	the effects of the war on syria 	the social sector (especially the family) 	the educational sector 	the economic sector 	the security sector 	the service sector 	the demographic sector 	an overview of the electricity system and energy sources in latakia before the war 	the energy shortage in latakia during the war 	rationing hours 	peak power demand 	peak power demand 	energy resources 	causes of the energy shortage 	the current solutions to the shortage 	effects of the current solutions 	health 	environment 	education and social problems 	designing an emergency system 	for unstable sources 	for stable sources 	the advantages of the proposed emergency system if it was applied before the war 	for the electricity situation 	for the environment and health 	conclusions 	references clinical guidelines: understanding effective treatments of myofascial trigger points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . journal of bodywork and movement therapies ( ) ( ), ^ r publishedby elsevier science ltd. doi: . /yjbmt. . , available online at http://www.idealibrary.com on david simons monticello street, covington, ga usa. correspondence to: d. simons tel: + ; fax: + e-mail: loisanddavesimons@earthlink.net journ understanding effective treatments of myofascial trigger points . . . . . . . . . . . . . . . david g. simons this article considers specific treatment approaches and the role of etiological mechanisms in terms of clinical feature characteristics of mtrps: increased muscle tension, pain and tenderness, painful stretch range of motion, initiating causes of mtrps. final sections note additional treatments that are currently used, and summarize the etiological and clinical distinctions between mtrps and fibromyalgia. c l i n i c a l g u i d e l i n e s . . . . . . . , ; al of bo introduction truly effective treatment of neuromusculoskeletal pain often hinges on accurate identification of the sources of the pain. myofascial trigger points (mtrps) are unbelievably common yet commonly overlooked or poorly treated because the initial training of so few medical practitioners includes table widespreadnatureofmtrps common diagnoses common trigg tension-type headache sternocleidom and temporal frozen shoulder subscapularis deltoid muscl epicondylitis finger and h carpal tunnel syndrome scaleni, finge atypical angina pectoris left pectorali lower back pain quadratus lu thoracolumba gluteus maxim dywork and movement therapie adequate instruction in the identification and treatment of mtrps. although this article concerns primarily treatment of mtrps, it is important to appreciate how remarkably common mtrps are and how often they are a major cause of a patient’s musculoskeletal pain complaint. table lists a number of commonly used diagnostic terms er point causes astoid, upper trapezius, posterior cervical, is , supraspinatus, pectoralis major and minor, es and extensors, supinator, and triceps brachii r extensors s, major intercostals mborum, iliopsoas, r paraspinals, rectus abdominis, piriformis, us and medius s april simons that only identify the region of pain, but not its cause. these diagnostic terms are not diagnoses. identification of mtrps that are causing a patient’s pain is a diagnosis. as outlined in box , the likelihood of a trigger point (trp) causing the patient’s pain should be box diagnostic featuresofactivemtrps [basedonsimonsetal. fthe trigger pointmanual,vol. ,ed. includingtable . b p. ] history k regional aching pain complaint– onset related to acute, chronic, or repetitive muscle overload. k pain intensity usually related to movement or positioning but may become continuous when severe diagnostic findings k painful limit to stretch range of motion k palpable taut band with exquisitely tender nodule k pressure on tender spot elicits pain familiar to patient and often a pain response (jump sign) confirmatory findings k local twitch response induced by snapping palpation or needle penetration of mtrp and evidenced by movement detected by vision, palpation, or ultrasound imaging k pain or altered sensation in expected location (published referred pain patterns for that muscle) k demonstration of endplate noise from an electromyographic needle gently inserted into the mtrp box myofascialtriggerpointscanbe inaccessibletopalpationbecauseof: klayer(s) of fat kintervening muscles(s) kintervening aponeuroses ktense, thick subcutaneous tissue kinadequate palpation skill journal of bo established by taking a careful history of the onset and course of the pain. the presence of the trp should be established by diagnostic findings of the physical examination whenever possible. the strength of the diagnosis can be reinforced by confirmatory findings, some of which are also valuable for research purposes. box lists reasons why mtrps may be inaccessible to palpation for diagnostic purposes, making it necessary to rely on clinical judgment. box identifies features of mtrps that clarify how to distinguish them from other conditions. fortunately, the kinds of pathophysiological mechanisms responsible for mtrps are becoming clear and can explain why some therapeutic approaches are so effective, and why others are of limited benefit for this condition. box distinguishingfeaturesofmtrps k mtrps produce specific regional pain complaints and not widespread, total body pain and tenderness k for practical purposes, only mtrps are points of spot tenderness in a palpable taut band k not all tender points are mtrps k all mtrps are tender points (points of spot tenderness) k referred tenderness as well as referred pain is characteristic of mtrps k all mtrps have a taut band k not all taut bands are palpable (requires sufficient palpation skill and accessibility) k all active mtrps cause a clinical pain (sensory disturbance) complaint k only an active mtrp when compressed reproduces the clinical sensory symptoms. a latent mtrp produces no clinical sensory (pain or numbness) complaint. dywork and movement therapies the concept of etiology used here is based on the endplate (integrated) hypothesis that is fully described in two books (simons et al. , pp. – ; mense et al. , pp – ). this is a valuable working hypothesis for understanding current clinical practice and future research. many details remain to be refined or filled in. increased muscle tension clinicians have recognized for more than a century that effective treatment of painful, tense, tender muscles includes stretching the involved muscle fibers, either locally in the region of tenderness (massage) or by lengthening the muscle as a whole. frequently mtrps were the cause of the symptoms and were what was being treated. the reason that muscles with mtrps feel abnormally tense on palpation and have a reduced stretch range of motion is the increased tension of the palpable taut band that is associated with the mtrp. this palpable increase in muscle tension is commonly mistaken for muscle spasm. muscle spasm is clearly identified by motor unit activity that is identified electromyographically (simons & mense ) while taut bands show no motor unit activity at rest. the problem the increased tension of the palpable taut band is the result of regional shortening of the sarcomeres of numerous involved muscle fibers in the taut band. one demonstrated cause of that shortening of an affected muscle fiber is the presence of a contraction knot (simons & stolov ) that would be in the region of a motor endplate (simons , mense et al. ). the sarcomeres in the contraction knot appear maximally april tendon normal muscle fibre contraction knot (central trigger point) involved muscle fibre tendon tension enduced enthesopathy attachment trigger point fig. unequal sarcomere length: comparison of the uniform, equal length of all sarcomeres of a normal muscle fiber compared to the severe shortening of a group of sarcomeres near the center of the fiber and the compensatory lengthening of the remaining sarcomeres. note locations of central and attachment trigger points. voluntary contraction t en si on . µ length . µ voluntary contraction fig. voluntary contraction. the length– tension curve below shows that the relatively few (roughly in but maximally contracted sarcomeres of contraction knots are in a range where they can no longer exert any additional contractile force because they are already maximally shortened. on the other hand, the much larger number of slightly elongated sarcomeres between the trigger point and the muscle fiber attachments are at, or close to, the optimal strength portion of the curve. therefore, gentle voluntary contraction allows the lengthened sarcomeres to exert an effective elongation force on the shortened sarcomeres of the contraction knot. myofascialtrigger points contracted (hypercontracted), while remaining sarcomeres of an involved muscle fiber are noticeably stretched to compensate for the missing length of the shortened sarcomeres. due to the nature of titin – the spring-like molecule that holds the myosin molecules in place – the maximally contracted sarcomeres would tend to become stuck in this shortened position. the effect of these shortened sarcomeres is one likely source of increased resting tension in an involved muscle fiber. this effect is transmitted through the fiber as increased resting tension of the stretched sarcomeres (wang , ). the central mtrp is located close to the middle of the muscle fiber where the motor endplates are found. the primary goal of manual therapy treatment is to restore uniform sarcomere lengths in the affected muscle fibers that have developed unequal sarcomere lengths as illustrated in figure . solutions figure illustrates why a gentle muscle contraction tends to equalize sarcomere length in fibers afflicted with the dysfunction that is characteristic of mtrps. the relatively few (about in a dog biopsy [simons & stolov ]) maximally contracted sarcomeres of the contraction knot are already as short as they can get. therefore, based on the sarcomere length- tension curve, those sarcomeres are unable to produce any additional tension. on the other hand, the much larger number, about , in a -cm ( / -inch) long muscle fiber (assuming . mm mid-range sarcomere length– mm/cm; sarcomeres/cm� cm= sarcomeres/ cm muscle fiber) is a ratio of : between the number of shortened contraction-knot sarcomeres and the number of lengthened sarcomeres. the shortened sarcomeres are greatly journal of bo outnumbered. the remaining, somewhat stretched, sarcomeres in that fiber are still in the optimal range of their length-tension curve. therefore, the fully shortened, weak sarcomeres are readily overpowered by the remaining strong sarcomeres during a gentle voluntary contraction (see fig. ). time can be a critical factor. because of the stickiness of the titin molecules, releasing them can be expected to take time, and clinical experience confirms that slowly sustained stretches are much more effective at releasing mtrp tightness than rapid brief stretches. as the shortened sarcomeres lengthen, the stretched sarcomeres now return toward normal length. unfortunately, as soon as the muscle relaxes, the sarcomeres immediately tend to return to their previous state unless something more is done. figure presents schematically the essence of postisometric relaxation or contract–relax. contraction alone is not adequate treatment. the gentle (approximately % of maximum) contraction is immediately followed by relaxation and movement to take up slack that develops in the muscle. better terminology might be ‘postisometric relaxation and release’ or ‘contract–release’. the term ‘stretch’ could be used in place of ‘relax’ or ‘release’ but that term has been avoided because it is so commonly associated with forceful movement and this technique should dywork and movement therapie be a painless, gentle one. figure illustrates the stepwise nature of the process. methodsofrelease the relaxation and release phase can be accomplished in a number of ways. immediate elongation of the muscle encourages equalization of sarcomere lengths throughout the length of affected muscle fibers, and when done slowly helps to reset the new sarcomere lengths so they tend to stay that way. this principle for effectively releasing muscle tension s april fig. postisometric relaxation (contract– release). the essence of many effective myofascial trigger point release techniques is to repeat a series of incremental releases each of which are achieved by a gentle voluntary contraction of the muscle that is followed by active or passive elongation of the muscle to restore full pain-free range of motion and to inactivate its trigger points. other names that are used for this principle of treatment include muscle energy techniques, and contract–relax. fig. trigger point pressure release. demonstration of the principle responsible for the effectiveness of this treatment method. individual sarcomeres, like a balloon are constant-volume structures. compressing either one of them in the vertical dimension cause an increase in the horizontal dimension. thus, finger pressure applied downward on a mtrp tends to lengthen sarcomeres that are shortened for any reason and can be responsible for the tension of the taut band. fig. finger pressure and voluntary contraction. this figure illustrates how the effects of simultaneous application of trigger point pressure release and voluntary contraction are additive. simons (and for release of restricted joint movement that is often caused by muscle tightness) has been recommended by various schools of thought with many names, such as ‘contract–relax’, ‘postisometric relaxation’, and ‘muscle energy technique’. in any case, full relaxation of the patient is an essential prerequisite to effective release. release can be achieved passively or actively. in passive release, the movement is done for the patient; in active release it is done primarily by the patient. lewit ( ) emphasizes the advantage of using gravity for passive release. when properly positioned for appropriate muscles, gravity is gentle and helps the patient relax more completely. much operator skill is required to sense the tissue resistance that journal of bo indicates how much movement is optimal. too little movement is ineffective and too much movement, too fast causes pain that inhibits release. with active release, the patient extends the muscle to take up the slack by actively contracting its antagonist muscles. this has the advantages of adding the effect of reciprocal inhibition to facilitate release of the muscle being elongated. many patients can learn quickly to optimize the effort, but must understand what to do, why to do it, and have the innate capacity to learn to do it effectively. it can be a powerful tool for a patient’s home program. this technique is particularly useful for clinicians to treat their own mtrps and combines nicely with contract– release. figure illustrates ‘trigger point pressure release’ that is performed by simply applying gentle persistent digital pressure against the palpable tissue barrier in the mtrp. a sarcomere is a space of constant volume. like a balloon, if its height is reduced by compression, it becomes wider. this applies to the sarcomeres of a contraction knot. by applying digital pressure in a way that reduces their height, they must become longer, tending to normalize the length of all sarcomeres in that muscle fiber. the sticky, overcompressed titin molecules resist elongation of the short sarcomeres. again, if compression is applied for only a short period of time and then released, the shortened sarcomeres tend to return immediately to their previous state and little has been gained. however, if gentle compression is sustained until the clinician feels the release of tension, this corresponds to a degree of equalization of sarcomere length that can be demonstrated as an increased range of motion and reduced muscle tension. this is dywork and movement therapies the essence of the ‘trigger point pressure release’ technique and can be continued as long as additional release of tension occurs. figure demonstrates combined finger pressure and voluntary contraction. the combination of applying firm, gentle, persistent trp pressure release and sustained gentle voluntary contraction adds the impact of two effective ways of equalizing the sarcomere lengths and releasing muscle tightness. this combination is most effective when april abnormal ach release local sarcomere contracture local ischemia increased metabolism myofascialtrigger points it begins with the muscle in a comfortably stretched position. the muscle is gently extended until no slack remains. following each period of gentle contraction, the muscle is immediately gently extended to take up the slack that was produced by treatment. this helps the sarcomeres to retain their new lengths and establishes a new starting point for the next release cycle. figure shows trigger point massage – a trp-specific variation of deep massage that is particularly helpful in equalizing sarcomere length. it elongates the contraction knot sarcomeres, allowing the remaining stretched sarcomeres to shorten a bit. this massage is performed with the muscle extended to just eliminate slack. then the clinician starts by simultaneously applying bimanual digital pressure on the middle of the mtrp, short fingernail against short fingernail, and then pulls the fingers apart while maintaining gentle, firm pressure. pain and tenderness the local tenderness of the mtrp and its ability to refer pain to distant location depends primarily on the sensitization of nociceptors in the immediate region of the endplates mtrp fig. trigger point massage. this massage technique is specific for trigger points and requires two hands. it is an extension of trigger point pressure release and can be even more effective. it is designed to effectively lengthen the shortened sarcomeres of contraction knots in a myofascial trigger point and should be applied with the muscle extended to eliminate any slack. concept by c-z. hong, md. journal of bo that are associated electromyographically with endplate noise. endplate noise indicates abnormal endplate function. (simons ). endplate noise is characteristic of mtrps. (simons et al. ; couppe et al. ). figure outlines the basis of the energy crisis responsible for release of substances that sensitize local nociceptors. this positive feedback cycle starts (upper left corner) with resting release of grossly abnormal amounts of acetylcholine (ach) from the nerve terminal of the motor endplate (simons ). this leads to contraction knots and possibly other contractile effects that cause local ischemia and hypoxia (brückle et al. ), which are combined with a greatly increased energy consumption (local maximal sarcomere contractile activity). this combination of greatly increased sustained energy demand and loss of energy supply creates an energy crisis that causes release of sensitizing substances pain local energy crisis autonomic nerves nociceptors fig. energy crisis. schematic diagram of steps involved in the positive feedback loop of the end plate integrated hypothesis. it shows the origin and results of the energy crisis characteristic of mtps. see text for explanation. dywork and movement therapies neurovasoreactive sensitizing substances (mense et al. , pp – ). any treatment that reduces the sarcomere shortening in the region of the mtrp reduces the energy consumption, which in turn reduces the release of sensitizing substances. the degree to which the released sensitizing substances get to actually sensitize nociceptors depends strongly on the closeness of the nociceptors to an affected motor endplate and that depends on variations in local anatomical structure. generally the endplate and nociceptors are near each other, but not always. this is why mtrps are primarily a motor dysfunction disease and only secondarily a pain phenomenon. the pain results secondarily from the endplate motor dysfunction. this helps to explain why there is only a general correlation between the motor expression of a mtrp (the taut band) and its degree of painfulness and why latent mtrps are so much more common than active ones. it is well established (simons et al. , p. , lewis et al. ; mcnulty et al. ; chen et al. ) that variations of local autonomic activity can affect acetylcholine release at endplates. activation of local autonomic nerve fibers by the neurovasoreactive substances would complete the feedback loop and induce continued excessive release of acetylcholine by the motor endplate. this also explains why anxiety and nervous tension that increases autonomic activity commonly aggravates symptoms caused by mtrps. painful stretch range of motion a valuable clinical indicator of mtrps is painful restriction of stretch range of motion of the involved muscle. the pain is caused by increased tension on attachment april fig. relation between central and attachment trigger points. (a) schematic diagram looking down on a fusiform muscle such as the biceps brachii. the central trigger point (encircled *) is found close to the center of the muscle fibers that form a palpable taut band (dark fibers). attachment trigger points (open circles) are tender myotendinous attachments of taut band fibers due to enthesopathy (inflammatory reaction) caused by the sustained tension of the taut band fibers. that tension is caused by and can be relieved by normalizing, the contraction knots of the central trigger point. (b) schematic diagram of enlargement of a microscopic part of the trigger point. the fusiform enlargements of involved muscle fibers are produced by local maximal contraction of the sarcomeres that seem to be located in the region of a motor endplate. note that the remaining sarcomeres of the involved fiber are longer compared to the normal, uninvolved fibers. simons trps. during examination, it is frequently more convenient to examine first for an attachment trp rather than the central trp. attachment trps are more accessible and more readily identified than central mtrps, especially in muscles such as levator scapulae, gluteus medius and iliopsoas. figure a explains the relation between the central trp and attachment trps. the central trp causes the tension of the taut band journal of bo that produces the attachment trp. the taut band imposes sustained abnormal tension on the myotendinous junctions where the muscle fibers attach to the muscle tendon. these attachments are complicated delicate structures that are not designed to tolerate unrelieved, constant tension. muscles normally contract then relax, contract then relax, with appreciable periods of relief from tension between contractions. this abnormal tension induces dywork and movement therapie inflammatory changes (enthesopathy) that often include some edema, release of pain- inducing sensitizing substances and eventually some degenerative changes (fassbender ) that account for the attachment trp. clinically, the attachment trp can be identified by local spot tenderness in the region of the myoneural junctions, sometimes referral of familiar pain when digitally compressed, and sometimes palpable induration. frequently the examiner can identify a palpable taut band extending toward the central trp that is responsible for the attachment trp. initiation of trigger points acute or chronic muscle overload initiates the excessive release of acetylcholine, which produces the local energy crises that can account for the clinical characteristics of mtrps. the motor endplate is a synaptic junction with basically the same delicate structure (fig. ) as that of the myriad of synapses that conduct the business of the central nervous system with one very important difference. the central nervous system synapses are cushioned from mechanical trauma by suspensory ligaments encased in a protective bony cage. the motor endplates are exposed to all the mechanical stresses and strains that beset the muscular system, but with no special protection. it is little wonder that, with normal use, it is only a matter of time until the muscles develop the disease caused by mechanical trauma, myofascial trigger points. the pioneer muscle physiologist, liley, in observed that almost any kind of mechanical stimulation of the endplate induced the same kind of electrical activity that nearly years later was proven by another physiologist team to be caused by excessive release of acetylcholine s april table distinguishingmtpmtrpsand¢bromyalgia mtrps fibromyalgia peripheral muscular origin central nervous system origin female to male ratio : female to male ratio – : local or regional pain widespread, general pain focal tenderness widespread tenderness throughout muscle feels tense (taut bands) muscle feels soft and doughy restricted stretch range of motion commonly hypermobile examination for mtrps anywhere examination for prescribed tender points immediate response to mtrp injection delayed response to mtrp injection may also have fibromyalgia nearly all also have mtrps fig. motor endplate synaptic structure and function. schematic cross-section of the terminal nerve fiber, synaptic cleft, and postjunctional muscle fiber membrane. it also shows how the electrical signal of the motor nerve is normally converted to a chemical signal and then back to an electrical signal that is propagated along the muscle fiber membrane in both directions. the original electrical signal (propagated action potential along the nerve membrane) causes the presynaptic nerve terminal to simultaneously release many packets of acetylcholine that diffuse across the synaptic cleft. on arrival at the postjunctional membrane of the muscle cell, this chemical messenger is converted back to an electrical signal when the acetylcholine activates acetylcholine receptors located in the postjunctional membrane. normally just a few packets per second of acetylcholine are released randomly under resting conditions. myofascialtrigger points (heuser & milelli ; ito et al. ). this endplate noise is the same kind of electrical activity that is characteristic of mtrps (simons et al. ). liley ( ) reported that once it was initiated, this dysfunction persisted, which is also characteristic of mtrps. the classical history of onset of myofascial pain caused by mtrps is either an acute muscular overload (sometimes due to an accident, poor coordination when fatigued, or an awkward movement) or chronic overload caused by sustained muscle contraction or by monotonous repetition of the same movement. box additionalwaysoftreatingmtrps k techniques to augment release (exhalation, eye movement) k reciprocal inhibition (voluntary contraction of antagonist muscle) k dry needling (acupuncture technique) ktherapeutic ultrasound k strain–counterstrain k microcurrent application k laser irradiation k injection journal of bo additional treatments box lists additional treatments that some clinicians find effective in treating mtrps. augmentation techniques are well described by lewit ( , ) and by simons et al. ( ). reciprocal inhibition is described as such by simons et al. ( ) and by lardner ( ). the value of dry needling has been reported by hong ( ) and baldry et al. ( ). the value of therapeutic ultrasound, especially with regard to patients with fibromyalgia was reported by lowe et al. ( ). although the mechanisms described to explain their clinical effectiveness are not convincing, many clinicians find dywork and movement therapie strain–counterstrain, microcurrent application, and laser irradiation useful forms of treatment for mtrps (simons et al. ). injection of the mtrp itself with an analgesic medication such as procaine or lidocaine are well-established techniques commonly used by physicians (simons et al. ). occasionally, as pointed out by thompson ( ) the taut bands of mtrps may be serving a useful function as a stabilizing mechanism. in this case it is wise to correct the underlying cause of instability before releasing the mtrp tension. in fact, correcting the underlying instability often results in spontaneous resolution of the mtrp (thompson ). fibromyalgia and trigger points table summarizes features that distinguish mtrps from fibromyalgia. recent advances now make it clear that myogenic mtrps and central nervous system fibromyalgia syndrome (fms) are etiologically and pathophysiologically distinct conditions (mense et al. , chapters & ). the regional-only pain of mtrps can appear confusingly like the widespread pain of fms when there is multiple regional involvement in one patient. the palpable taut band is a reliable distinguishing feature of mtrps, when it is accessible (see box ). s april simons restriction of stretch range of motion is characteristic of mtrps, not fms, but most fms patients also have mtrps. totally different examinations are required to make each diagnosis (mense et al. ). mtrp injections respond differently in patients who do or do not also have fms (hong & hsueh ). it is becoming increasingly clear that most, if not nearly all, fms patients also have pain-generating mtrps. one important study of fms patients (donaldson et al. ) and two case reports (starlanyl & seffrey ; donnelly in press) give remarkable insight into the close relationship between the two distinctly different conditions. the donaldson paper calls attention to the importance of electroencephalogram (eeg) changes in fms patients and raises the likely possibility that a software- type brain dysfunction is the critical dysfunction in fms patients that disturbs normal functioning of all organ systems. donnelly (in press) documents the repeated observation that some fms patients are able to clearly distinguish between pain of fibromyalgia and that caused by mtrps. fms produces a generalized pain relatively independent of movement. mtrps produce a regional deep aching pain and are more strongly related to muscular activity. the author personally knows a number of medically trained patients who describe convincingly their ability to distinguish the two sources of pain and then successfully initiate different remedial action for each. references baldry pe, yunus mb, inanici f myofascial pain and fibromyalgia syndromes. churchill livingstone, edinburgh. brückle w, suckfüll m, fleckenstein w, weiss c, müller w gewebe-po - messung in der verspannten rückenmuskulatur (m. erector spinae). journal of bo zeitschrift für rheumatologie : – chen j-t, chen s-u, kuan t-s, chung k-c, hong c-z phentolamine effect on spontaneous electrical activity of active loci in a myofascial trigger spot of rabbit skeletal muscle. archlves of physical medicine and rehabilitation : – couppe c, midttun a, hilden j, jorgensen u spontaneous needle electromyographic activity in myofascial trigger points in the infraspinatus muscle: a blinded assessment. j musculoske pain ( ): – donaldson ccs, sella, ge, mueller hh fibromyalgia, a retrospective study of consecutive referrals. canadian journal of clinical medicine ( ): – donnelly j (in press) physical therapy approach to myofascial trigger points and fibromyalgia: a case report. journal of musculoskeletal pain fassbender hg non-articular rheumatism chapter . in: pathology of rheumatic diseases. springer-verlag, new york pp – heuser j, miledi r effect of lanthanum ions on function and structure of frog neuromuscular junctions. proceedings of the royal society (london series b) : – hong c-z lidocaine injection versus dry needling to myofascial trigger point: the importance of the local twitch response. american journal of physical medicine rehabilitation : – hong c-z, hsueh t-c difference in pain relief after trigger point injections in myofascial pain patients with and without fibromyalgia. archives of physical medicine and rehabilitation ( ): – ito y, miledi r, vincent a transmitter release induced by a ‘factor’ in rabbit serum. proceedings of the royal society (london series b) : – lardner r stretching and flexibility: its importance in rehabilitation. journal of bodywork and movement therapies ( ): – lewis c, gevirtz r, hubbard d et al. needle trigger point and surface frontal emg measurements of psychophysiological responses in tension- type headache patients. biofeedback & self-regulation ( ): – lewit k postisometric relaxation in combination with other methods of muscular facilitation and inhibition. manual medicine : – lewit k manipulative therapy in rehabilitation of the locomotor system, nd ed. butterworth heinemann, oxford dywork and movement therapie liley aw an investigation of spontaneous activity at the neuromuscular junction of the rat. journal of physiology : – lowe j-c, honeyman-lowe g ultrasound treatment of trigger points: differences in technique for myofascial pain syndrome and fibromyalgia patients. medecine du sud-est: april-may-june, no. : – mcnulty wh, gevirtz rn, hubbard dr, berkoff gm needle electromyographic evaluation of trigger point response to a psychological stressor. psychophysiology ( ): – mense s, simons dg, russell ij muscle pain: understanding its nature, diagnosis, and treatment. lippincott, williams & wilkins, philadelphia. (endplate hypothesis, pp. – ) simons dg, mense s understanding and measurement of muscle tone related to clinical muscle pain. pain : – simons dg, travell jg, simons ls travell & simons’ myofascial pain and dysfunction: the trigger point manual, vol. , ed. . williams & wilkins, baltimore. (endplate hypothesis, pp. – ) simons dg, stolov wc microscopic features and transient contraction of palpable bands in canine muscle. american journal of physical medicine : – simons dg do endplate noise and spikes arise from normal motor endplates? american journal of physical medicine rehabilitation ( ): – simons dg, hong c-z, simons ls ( ) endplate potentials are common to midfiber myofascial trigger points. american journal of physical medicine rehabilitation ( ): – starlanyl dj, jeffrey jl geloid masses in a patient with both fibromyalgia and chronic myofascial pain. physical therapy case reports ( ): – . thompson b neuromuscular massage therapy perspective. journal of bodywork and movement therapy ( ): – wang k sarcomere-associated cytoskeletal lattices in striated muscle chapter . in: shay j.w. (ed.) cell and muscle motility, vol. , kluwarts plenum, new york wang k titin/connectin and nebulin: giant protein rulers of muscle structure and function. advances biophysics : – s april 	introduction 	table 	increased muscle tension 	the problem 	solutions 	figure 	figure 	figure 	figure 	figure 	pain and tenderness 	figure 	figure 	painful stretch range of motion 	figure 	initiation of trigger points 	figure 	additional treatments 	fibromyalgia and trigger points 	table 	references design and fabrication of pellet stove design and fabrication of pellet stove kunjan patel hardik rathod prof. dharmendra sapariya , ug student, assistant professor department of mechanical engineering , , , indus institute of technology and engineering, ahmedabad, gujarat, india abstract:- a pellet stove is mechanical device which uses compressed wood or biomass pellets to create a source of heat for residential and industrial spaces [ ]. these stoves are electronically sophisticated appliances that offer an environmentally friendly and low-cost heating option. its fuel consists of wood chips, waste of nuts, grasses, and lumber yard waste. the pellets which are filled in the combustion chamber is then ignited [ ]. pellets are heavily compressed, so they're dense and low in moisture, creating a hotter flame. the combustion chamber serves as the carburettor for the stove, mixing the air and fuel to create combustion. the ashes from the burnt pellets are captured in an ash pot, which needs to be cleaned periodically. wood pellet stoves are generally small, and the bags of pellets are about the size of a mulch bag, making them easy to store. they're also easy to operate; they only require loading pellets and igniting the flame. because the fire is contained in a heat box inside the unit, there is a minimum of smoke, which lessens the smell in your home and prevents the outside of the unit from heating up. pellets create considerably less ash than firewood [ ], giving off less creosote, a flammable by product of combustion that can build up and cause chimney fires. keywords: eco friendly fuel, low-cost, natural process introduction: energy is the key input for socio-economic development of any nation. the fast industrialization and rapid urbanization have generated a high demand of energy in all forms i.e. thermal, mechanical and electrical. to meet this ever- increasing demand, fossil fuels such as coal, oil and natural gas have been overexploited in an unsustainable manner. the overexploitations of fossil fuels have been posing serious environmental problems such as global warming and climate change [ ]. we are more dependent on imports of petroleum. to concerns over health, climate change and energy security so the energy crisis of the world to look for less expensive and more efficient. to solve mentions problem and efficient cooking the pellet stove is best option we had. by provide efficient cooking stoves to rural areas an effort to reduce air pollution and conservation of other energy sources. the main reason behind less pollutant emission by pellet stove is wood pellet which containing less carbon [ ]. our objective is to produce residential multi burner pellet stove which can replace domestic home appliances as gas burner. we will try to optimize cost effective and high efficient cooking by using multi burner pellet stove. pellet stoves could also significantly reduce greenhouse gas emissions and zero percentage co emission [ ]. such a program would avoid percent of the premature deaths and disability from respiratory infections, heart disease, and bronchitis that would have occurred in , saving some . million years of healthy life that would otherwise be lost from air pollution exposure, the study found[ ]. working principle: the pellets are filled in combustion chamber to within cm of the secondary air supply. then pellets are ignited at the top zone with a match and allowed to burn for a minute or so. when a stable flame is established all around, using the power supply or rechargeable battery fans are operated and primary air is supplied to the combustion chamber. primary air is used for “gasification process” of pellets. then the secondary air is supplied to the top of the combustion chamber with the help of the fan [ ]. fig :- combustion process combustion process is done in four zones. ➢ ungratified pellets: - this is the zone where the unburnt pellets are placed. it is above the grate plate in combustion chamber. ➢ pyrolysis zone: - pyrolysis is a thermo chemical decomposition of organic material at elevated temperatures without the participation of oxygen. the pyrolysis gas is forming in this zone due to the decomposition of pellets. ➢ intermediate zone: - this is the zone, in which the formed pyrolysis gas goes to the flaming zone. international journal of engineering research & technology (ijert) issn: - http://www.ijert.org ijertv is (this work is licensed under a creative commons attribution . international license.) published by : www.ijert.org vol. issue , may- www.ijert.org www.ijert.org www.ijert.org ➢ flaming zone: - in the flaming zone, gas is burnt with the help of secondary air. litreture review: larry hepper, carl williamson show a pellet stove is disclosed comprising a reverse flow heated air pathway defined by stove sections. in an illustrated embodiment, the space between upper and lower stove sections is open to provide a heating or oven area. the stove can be readily disassembled in part for easy portability [ ]. gary wisener says a pellet stove utilizing gravity feed and natural draft more effectively and efficiently burns pellet fuel while producing less air pollution and ash. in one embodiment, the pellet stove has a primary combustion area comprising a burn unit removably disposed in the vent tube, a feed tube defining a fuel chamber above the burn unit and a secondary combustion area, comprising a burn box defining a secondary burn chamber, below the burn unit. a control mechanism controls the air flow to regulate the heat generated by the pellet stove [ ]. material selection: ➢ insulating material for the insulating purpose different material like cerawool, ceramics are there. as we know cerawool is good insulator but due to cost of cerawool is high and we have to provide some material to protect cerawool against direct contact with heat, in that case pellets are over burnt due to natural conduction of material. to eliminate above mentioned problem we select ceramic as insulating material. ➢ grate for the grate material we can select m.s. and cast iron. due to the advantages of cast iron (c.i.) like easily machinability, low cost, low weight so we select cast iron as grate material. ➢ supporting structure for supporting the structure and proving good strength, ductile material, easily available we select the mild steel as outer body. comparison of energy rating of fuels: this is a breakdown of what the most common forms of energy rating. wood pellets , kj/kg shelled corn , kj/kg natural gas , kj/kg propane , kj/liter electricity-resistance , kj/kwh bituminous coal , kj/kg anthracite coal , kj/kg seasoned firewood , kj/kg fuel oil , kj/liter kerosene , kj/liter calculation calculation for . kg stove : minimum air / kg of fuel kg/kg of fuel volume . × - m diameter of pellet stove . mm height of pellet stove mm stoichiometric air required . kg primary fan cfm - . voltage - v ampere - . a dimension - x x mm secondary fan cfm - . voltage - v ampere - . a dimension - x x mm d design: fig :- pellet stove fig :- assembly drawing of pellet stove international journal of engineering research & technology (ijert) issn: - http://www.ijert.org ijertv is (this work is licensed under a creative commons attribution . international license.) published by : www.ijert.org vol. issue , may- www.ijert.org www.ijert.org www.ijert.org conclusion:- it is conclude that, the wood pellet stove has been started and operated indoors without creating pollution with high grade of thermal energy. the wood pellet stove is eco- friendly, which emit less carbon dioxide compare to other fuel. we are introducing multiple burner pellet stove which is useful for domestic purpose such as cooking, heating etc. our stove has multi burner which has different configuration and dimension so we can use it lower and higher capacity as per requirement. however, we believe that there is still much work to be done in optimizing the stove for various fuels, determining the effect of moisture, adapting it to various cooking situations and developing other uses. for that reason we are publishing our preliminary results here and hope that others will help adapt these principles to improve world cooking and energy conservation. references: [ ] gravity feed natural draft pellet stove us a publication date: - date: - aug gary wisener [ ] https://patents.google.com/patent/us ?oq=pellet+stove (pellet stove) [ ] effect of wood fuel on the emissions from a top-feed pellet stove o sippula, k hytönen, j tissari, t raunemaa energy fuels , vol- , - publication date:february , [ ] emission from realistic utilization of wood pellet stove energy volume , - - , pages - g toscano, d duca, a amato, a pizzi publication date: february , [ ] high efficiency wood pellet stove-us a us patent energy fuels ,vol- , - jl vossler, wk tomooka publication date: - - [ ] mobile pellet stove with thermal barrier and ventilated firepot us a us patent tm burke, lt burke publication date: - - [ ] pellet stove with enhanced air circulation efficiency- us a us patent environ. sci. technol , vol- , - tm burke, wl burke publication date: - - [ ] pellet stove fuel volume , - - , pages - l hepper, c williamson publication date: - - [ ] natural draft automatic feed pellet stove fuel processing technology volume , june , pages - ma jarvi, b. mechman, k. blackhard [ ] particle emissions from pellets stoves and modern and old-type wood stoves biomass and bioenergy vol.- , issue , august , pages - ls bäfver, b leckner, c tullin, m berntsen international journal of engineering research & technology (ijert) issn: - http://www.ijert.org ijertv is (this work is licensed under a creative commons attribution . international license.) published by : www.ijert.org vol. issue , may- https://patents.google.com/?inventor=gary+wisener https://pubs.acs.org/doi/abs/ . /ef e https://scholar.google.co.in/citations?user=canblv aaaaj&hl=en&oi=sra https://scholar.google.co.in/citations?user=canblv aaaaj&hl=en&oi=sra https://www.sciencedirect.com/science/article/pii/s https://www.sciencedirect.com/science/journal/ https://www.sciencedirect.com/science/journal/ / /supp/c https://scholar.google.co.in/citations?user= ddzrqyaaaaj&hl=en&oi=sra https://scholar.google.co.in/citations?user= ddzrqyaaaaj&hl=en&oi=sra https://scholar.google.co.in/citations?user=dl fr aaaaaj&hl=en&oi=sra https://patents.google.com/patent/us a/en https://patents.google.com/patent/us a/en https://patents.google.com/patent/us a/en https://patents.google.com/patent/us a/en https://patents.google.com/patent/us a/en https://patents.google.com/patent/us b /en https://www.sciencedirect.com/science/journal/ / /supp/c https://patents.google.com/patent/us b /en https://www.sciencedirect.com/science/journal/ https://www.sciencedirect.com/science/journal/ https://www.sciencedirect.com/science/journal/ / /supp/c https://www.sciencedirect.com/science/article/pii/s https://www.sciencedirect.com/science/article/pii/s https://www.sciencedirect.com/science/journal/ https://www.sciencedirect.com/science/journal/ / / https://scholar.google.co.in/citations?user=g_cj p aaaaj&hl=en&oi=sra www.ijert.org www.ijert.org www.ijert.org virus-host interactions leading edge select virus-host interactions viruses display remarkable specificity in both the host species and the cell types that they infect. understanding this specificity reveals insight into the basic host components that are required for the viral life cycle and host restriction factors that limit the virus. this issue’s select takes a closer look at some of the limitations to virus replication, including a report identifying an unexpected origin of a controversial retrovirus. in wild-type (left) and viperin knockdown (right) fibroblasts that are infected by human cytomegalovirus, viperin is induced only in the wild-type cells. the viral vmia protein (green) is present in mitochondria in both, but the actin cytoskeleton (red) is disrupted only in the viperin-expressing cells. image courtesy of j.-y. seo and p. cresswell. hcmv turns defense into offense given that viruses have evolved many mechanisms of counteracting host immune systems, it seems counterintuitive at first that human cytomegalo- virus (hcmv) would specifically induce expression of an antiviral host protein called viperin. seo et al. ( ) now resolve this conundrum by deciphering the activities of viperin and of a viral protein, viral mitochondria inhibitor of apoptosis (vmia). they show that the direct binding of vmia to viperin and the resulting relocalization of viperin to mitochondria turn viperin into a weapon not against its intended target, but against the host. by adding a mitochondrial localization sequence to viperin, the authors provide evidence that many of the effects previously attributed to vmia are, in fact, due to mis- localized viperin. these effects include decreasing atp availability leading to abnormal cell enlargement (cytomegaly) and cytoskeletal disruption, which facilitates infection. to elicit the reduction in atp, viperin binds the hadhb subunit of the mitochondrial trifunctional protein (tfp), an enzyme that cata- lyzes multiple steps in mitochondrial fatty acid b oxidation. how viperin limits tfp function remains to be elucidated. also, given that other mechanisms of atp generation presumably remain intact, it is not known how the activity of vmia-bound viperin is precisely controlled to reduce the level of atp to a level that induces cytoskeletal disruption and cytomegaly, but not below a threshold that would trigger apoptosis. what is clear is that vmia-induced relocalization of viperin has a double advantage for the virus, reducing its antiviral activity but also turning the cell’s defense against itself, inducing a cellular energy crisis that facilitates viral infection. seo, j.-y. et al. ( ). science , – . human dendritic cells (blue pseudoco- loring). dendritic cells are largely refrac- tory to hiv- infection due to the expres- sion of the newly identified samhd protein. the photographs were deco- rated by the french artist fabrice hyber. the em image was obtained from olivier schwartz, stéphanie guadagnini, and marie-christine prevost (electron micro- scopy core facility, institut pasteur). protecting dendritic cells from hiv- infection three cellular proteins—apobec g, trim a, and tetherin—have been charac- terized as hiv- restriction factors. although potent under certain conditions, each of these hiv- restriction factors has limited activity in humans due to a variety of evolutionary adaptations of the virus. now, laguette et al. ( ) iden- tify a new hiv- restriction factor, samhd , that is highly active against hiv- in human cells because the virus has evolved no means to counteract this protein. samhd is highly expressed in dendritic and myeloid cells that are previously known to be nonpermissive to hiv- infection. they show that high-level expres- sion of samhd is sufficient to block hiv- infection in cells otherwise permissive to hiv- infection, and its removal in dendritic cell subsets significantly increases hiv- infection. to identify this factor, laguette et al. used the knowledge that certain nonpermissive cell types could be infected when forced to express the hiv- /siv accessory protein vpx, hypothesizing that vpx binds and degrades an hiv- restriction factor. pull-down of vpx-binding proteins in nonpermissive cell lines identified samhd , an interferon-g-inducible factor that is sensitive to vpx-mediated degradation. this data helps to explain why certain primary dendritic and myeloid cells that express the receptor and coreceptor for hiv- entry remain refractory to infection. further studies are needed to determine the mechanism of samhd inhibition of hiv- infection and the role of samhd in hiv- /siv pathogenesis. this finding will help our understanding of retrovirus pathogenesis and may open up new avenues for vaccine development. laguette, n., et al. ( ). nature. published online may , . . /nature . cell , july , ª elsevier inc. visualization of hepatitis c virus infec- tion in the liver of mice expressing human entry factors. image courtesy of a. ploss. breaking the species barrier developing model systems and methods to study human viral infections is typi- cally difficult because cell lines and animal systems can lack the expression of key host proteins that are necessary for viral replication and may contain cellular restriction factors that limit virus spread. two groups present new experimental models of hepatitis c virus (hcv) infection that overcome major hurdles for its study. triyatni et al. ( ) developed a method to produce infectious hcv particles of theoretically any genotype in mammalian cells without using the error-prone hcv replication machinery. interestingly, they find that expressing a subgenomic replicon of west nile virus (a flavivirus in the same family as hcv) makes cells capable of hcv assembly and release. the hcv genome and proteins could then be supplied as plasmids along with a plasmid-encoded bacteriophage rna polymerase that drives cytoplasmic transcription. this method is a major advance over current hcv culture systems because it avoids the viral adaptive mutations that typically accompany hcv replication in tissue culture and facilitates studies on an array of infectious primary viral variants. existing mouse models for hcv infection are useful but limited and involve transplantation of human hepatocytes into immunocompromised mice. dorner et al. ( ) have now taken an important step forward with the development of a more tractable mouse model for hcv infection. the researchers expressed each of the previously identified human hcv entry factors (cd , claudin , occludin, and scavenger receptor type b class i) in mouse hepatocytes. using recombinant hcv-expressing cre recombinase to infect mice that contain cre-activated luciferase or gfp/b-galac- tosidase reporters, hcv uptake could be detected in cells expressing cd and occludin or all four factors. because these animals are immunocompetent, dorner et al. are also able to determine the efficacy of various vaccine vectors against a variety of hcv genotypes, demonstrating the usefulness of this mouse model to the study of future hcv vaccines. triyatni, m., et al. ( ). plos pathog. , e . dorner, m., et al. ( ). nature , – . scientists delve into the mystery of xmrv. image courtesy of k. delviks- frankenberry and v. pathak. viral detectives uncover the origins of xmrv since the first report of a gammaretrovirus termed xenotropic murine leukemia virus-related virus (xmrv) in , numerous studies have debated its origins, as well as its link to disease. reports previously suggested that xmrv may be an artifact—a pcr contaminant—and others affirmed that it was an infectious human pathogen. what is xmrv’s true identity? according to paprotka et al. ( ), it accidentally arose through chance recombination events in a laboratory. the virus was originally discovered in human prostate tumors, but an identical virus was later found in a prostate cancer cell line. researchers looked at the genesis of these cell lines for clues to the origin of the virus. nearly two decades ago, human prostate tumors, which grow poorly in culture, were shown to grow well when serially passaged through nude mice, a method used to generate a number of the widely used prostate cancer cell lines. paprotka et al. isolated genomic dna from a number of different passages of the prostate cancer cells, as well as from the original tumor, and showed that none of the samples prior to contained xmrv dna. early xenografts and some mouse lines did, however, contain two replication-defective viruses, each highly homologous to xmrv on opposite ends of their genome, termed prexmrv- and prexmrv- . phylogenetic analysis of these two viral sequences suggested that prexmrv- and prexmrv- recombined when coexpressed in the same cell to generate xmrv during the passage of prostate tumor xenografts in mice that harbored these endogenous precursor viruses. thus, the short but tumultuous history of xmrv provides a cautionary tale of the awesome capacity of viruses, even those considered defective, to adapt and thrive in unexpected ways. paprotka, t., et al. ( ). science. published online june , . . /science. . kara lassen cell , july , ª elsevier inc. 	virus-host interactions assessing the effect of starch on density and caloric value in sawdust briquette for domestic energy utilization in north-western nigeria gsc advanced research and reviews, , ( ), – available online at gsc online press directory gsc advanced research and reviews e-issn: - , coden (usa): garrc journal homepage: https://www.gsconlinepress.com/journals/gscarr  corresponding author: dantani abdulmalik department of forestry and wildlife management, bayero university kano, p.m.b. . kano state. copyright © author(s) retain the copyright of this article. this article is published under the terms of the creative commons attribution liscense . . ( r e s e a r c h a r t i c l e ) assessing the effect of starch on density and caloric value in sawdust briquette for domestic energy utilization in north-western nigeria dantani abdulmalik , *, babangida abubakar , mukhtar ridwan bunza , zagga abubakar idris , abdulrashid inuwa and abanikanda jubril olatunde department of forestry and wildlife management, bayero university kano, p.m.b. . kano state. department of forestry and environment, usmanu danfodiyo university sokoto, p.m.b. , sokoto state. publication history: received on december ; revised on december ; accepted on december article doi: https://doi.org/ . /gscarr. . . . abstract the effect of starch on density, caloric value and specific fuel consumption were assessed in this research. composite sawdust briquettes were produced from the mixture of sawdust and starch within four treatments in a percentage ratio of : for treatment a, : for treatment b, : for treatment c and : for treatment d. densification of the mixtures was achieved using a manually operating briquetting machine and starch gel was used as a binding agent. the performance of briquette produced was examined under controlled cooking test. energy content was determined using oxygen bomb calorimeter. the results obtained from density according to treatments a, b, c and d respectively were . kg/cm , . kg/cm , . kg/cm . treatment d has the highest density of . kg /cm . the caloric value was determined from the heat of combustion with treatment b having the highest energy content of . cal/g, c= . cal/g, a= . calg, and d= . cal/g. specific fuel consumption was determined during controlled cooking test and the values for the respective treatments were a= . g, b= . g, c= . g, d= . g, and fire wood= . g. time taken to cook g of rice was obtained using wrist watch and the values were: a= min, b= min, c= min, d= min, and firewood had the highest value of min. results showed that, increase in the quantity of starch led to increase in density of composites. keywords: briquette; biomass; sawdust; densification; calorimeter; caloric value. . introduction wood is a predominant source of fuel in rural areas of the developing countries. about million people in developing countries depend on the wood biomass for their daily domestic energy need [ ]. the main problem with fuel wood utilization in nigeria is inadequate supply in arid region of the country [ ]. the production of briquette from agricultural and wood residue would have an appreciable impact meeting domestic energy requirement in the country which has problems of fuel wood scarcity [ ]. it was reported that the average world production of residue comprises million tons of sawdust, million tons of bark, and over million tons of crooked log. it was estimated that % of wood biomass processed in the saw mills in nigeria end up as a mill residue. the wood wastes generated in the country in were estimated to be . million m [ ]. this composes of slabs, ( %) bark ( %) and sawdust ( %). the slabs and barks are sometimes collected and used as firewood while sawdust can be converted to briquettes. it will be more useful as a source of fuel for domestic cooking. the problem of acute scarcity and deficit in supply of fuel wood has resulted in energy crisis in arid and semi-arid regions of the developing countries [ ]. fuel wood provides about % of the total energy consumption in africa, % for the countries of asia % for the latin american countries [ ]. https://www.gsconlinepress.com/journals/gscarr http://creativecommons.org/licenses/by/ . /deed.en_us https://doi.org/ . /gscarr. . . . https://crossmark.crossref.org/dialog/?doi= . /gscarr. . . . &domain=pdf gsc advanced research and reviews, , ( ), – trees are being indiscriminately cut or felled to meet the fuel wood demand with no systematic replacement until recently when desertification and soil erosion were experienced in some parts of the country [ ]. the implication of indiscriminate fuel wood cutting on tree diversity in the natural ecosystem per hectare in nigeria has been established. the tree diversity index in the savannah dropped from . % to . % before and after felling while in the rainforest, tree diversity before felling was put at . %, but dropped to . % after logging [ ]. there has been a considerable increase in the use of biomass energy worldwide in the recent years most especially in sub-saharan africa. it is expected that global production of wood fuel will increase moderately from , million m in to , million m in and , million m in [ ]. in alone, the proportion of total round wood production used for fuel wood in africa was % [ ]. in the case of nigeria, consumption of fuel wood rose from . million m in through . million m in to . million m in and has been predicted to rise to . million m by . briquette simply refers to a block of compressed coal dust, charcoal or sawdust and wood chips used for fuel and kindling. briquetting is the process of transforming the powdery or granular products into a more convenient solid size. this sometimes involves the use of binders (glue). these materials are compacted with the use of roller press. production of briquette, using sawdust will provide an alternative source of fuel which will reduce the rate at which our forests and woodlands are exploited for fuel-wood, and also reduce the rate at which this sawdust pollutes our environment. during the last century, africa’s forest area has been reducing drastically. in a short period of ten years, between and alone, africa lost about , ha of forest annually (i.e. negative annual changes of . % the highest of any continent in the world [ ] perhaps partly because of sourcing wood for fuel. wood constitutes about % of fuel supply in africa as a result of increasing population; briquette has come to stay in order to reduce the rate of the exploitation faced by our forest through conversion of these millions of cubic meters of sawdust as a source of fuel. . material and methods . . study area the research was carried out in sokoto energy research centre (serc) of usmanu danfodiyo university, sokoto. sokoto state has a landmass of , . km , the state is located between longitude ’ to o e and latitude to n. it is bordered in the north by niger republic zamfara state to the east and kebbi state to the south and west. [ ]. it has population of about , , [ ]. sokoto state fall within sudan savannah area of nigeria which is characterized by few scattered trees, and grasses that cover about % of the ground [ ], these plant species include adansonia digitata, balanite aegyptica, acacia nilotica, cynodon dactylon, andropogun gayanus [ ] the minimum and maximum temperatures are within the range of c and c respectively. the relative humidity ranges from – % [ ]: respectively. the warmest months are from february – april where the daytime temperature exceeds c ( f) the highest temperature recorded was . c ( . f) which was the highest temperature recorded in nigeria. the rainfall mostly starts in either early or late may and ends in september. the mean annual rainfall ranges from mm to mm which is un-evenly distributed [ ]. dry season mostly comes around october and last up to september. hammatan is windy and dusty, cold and dry seasons are both experience in the state. the soil in this area is mostly sandy to loamy with low soil fertility particularly in primary nutrients e.g. nitrogen, potassium, phosphorus [ ] . . experimental materials  sawdust: this was collected from kara market in sokoto metropolis. quantities used for treatment are, a= g, b= g, c= g, d= g.  starch: this was bought from zuru central market. previous studies by [ ] have shown that cassava starch is an acceptable binder that closely the requirements of briquetting in terms of relatively high bonding strength, low cost, in offensive odour emission and minimal need for drying. the amount of starch used based on the treatment include, treatment a= g, b= g, c= g and treatment d= g.  measuring instrument: weighting balance was used to measure the samples (sawdust and starch) before compression and after production of the composite (before and after drying).  briquetting machine: this is a machine locally made consisting of pipe, iron rod, metal sheath, piston etc. and was used to compress sawdust in to composite briquette. grams of food: g of rice was used in controlled cooking test.  improved wood burning stove: this was used in controlled cooking test.  timing instrument: a clock was used to determine the time taken for every session during controlled cooking test. gsc advanced research and reviews, , ( ), –  oxygen bomb calorimeter was used to determine the energy content of the composites figure oxygen bomb calorimeter density= dry weight wet weight equation ( ) 𝐂𝐚𝐥𝐨𝐫𝐢𝐜 𝐯𝐚𝐥𝐮𝐞 = w(cal ℃⁄ )×∆t(℃)−wire correction arsh free dry weight equation ( ) . . controlled cooking test (cct) controlled cooking test was carried out to cook g of rice which was uniform for all the samples of briquette produced at different ratio of binder. before the test, mass of the empty pot and initial mass of the briquette was measured. . . specific fuel consumption (sfc) specific fuel consumption and time taken to cook grams of food was computed from the equation below: according to [ ]. specific fuel consumption (sfc) for a controlled cooking test (cct) is expressed as: 𝑆𝐹𝐶 = (𝑀𝑓𝑜−𝑀𝑓𝑡)( −𝑋) 𝑀𝑝𝑐−𝑀𝑝 . mc equation ( ) gsc advanced research and reviews, , ( ), – where mc = mass of charcoal left (kg), mfo = initial mass of fuel before burning (kg), mft = final mass of fuel burnt (kg), the mass of charcoal mc left after the briquette were combusted will be negligible hence mc is assumed to be zero. according to [ ]. the time spent in controlled cooking test is given as: 𝑡 = 𝑡𝑜𝑡𝑎𝑙 𝑡𝑖𝑚𝑒 𝑠𝑝𝑒𝑛𝑡 𝑖𝑛 𝑐𝑜𝑜𝑘𝑖𝑛𝑔 𝑡𝑜𝑡𝑎𝑙 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑐𝑜𝑜𝑘𝑒𝑑 𝑓𝑜𝑜𝑑 𝑖. 𝑒 𝑡 = 𝑡 −𝑡 𝑀𝑝𝑐−𝑀𝑝 equation ( ) where: t = cooking time for kg of food stuff (min/kg), t = initial time before cooking (min), t = final time after cooking (min), mpc = mass of pot with cooked food (kg), mp = mass of empty pot, x = the moisture content value of fuel assumed to be zero i.e. % dryness. . . experimental design complete randomized design was used to test the effect of additive (binder) in sawdust briquette at each level of composition or ratio of sawdust to additive which are in four treatments, replicated three times. the briquettes produced from the above combination were subjected to anova to test for significant difference between the treatments. . . data collections sampled sawdust and binder were simultaneously measured using electronic weighting balance before the mixture. data were collected from compressed briquette produced before and after - drying. four treatments replicated three times treatments/mixtures percentage ratio a: sd gst g % - % : b: sd gst g %- % : c: sd gst g %- % : d: sd gst g % : before controlled cooking test, the weight of the composite briquette and weight of the firewood were measured. density of the composite was also determined the test was also carried out between the best treatment and the firewood to see the possibility of replacing firewood with briquette to reduce the rate of exploitation of our natural forests. . . data analysis the data obtained from the experiment were subjected to (anova) analysis of variance to test the performance of composite briquette to see whether there is significant difference in the composites produced at % level of significance and the best treatment was tested against firewood. spss statistical package version was used. . results . . density the results in table shows the mean density of the briquettes produced from four different treatments made of the following combinations of sawdust and starch. treatment a= : of sawdust and starch, treatment b= : , treatment c= : , treatment d= : respectively. it was observed that there was significant difference between the treatments (p< . ). the highest density was recorded in treatment d = . g/cm , followed by treatment c= . g/cm ,treatment b= . g/cm , and the least was found to be treatment a with . g/cm , this indicate that increase in the quantity of starch leads to the increase in density of the composites produced. gsc advanced research and reviews, , ( ), – table mean density (g/cm ) of the composite briquettes in treatments (a, b, c, d) s/no treatments mean and sd a . ± . b b . ± . ab c . ± . ab d . ± . a means followed by the same letter are not statistically different according to duncan multiple range test (dmrt) at % level of significance. . . energy (caloric value) table shows the mean energy of the briquettes produced, with treatment b having the highest mean ( . cal) and the lowest mean was recorded in treatment d with value of . cal. statistically there is no significant difference between the energy content of the briquettes produced. table mean energy (cal/g) obtained from sampled briquettes based on treatments (a, b, c, d) s/no treatment mean and se a . ± . ns b . ± . ns c . ± . ns d . ± . ns ns= no significant difference. . . specific fuel consumption (sfc) and time spent in cooking according to the research carried out it was observed that the lowest value of fuel consumed by g of rice was recorded in treatment b with about . g, followed by c with . g, d with value of . and a with value of . g.time spent in cooking g of rice, the least was recorded in treatment b with about min/kg, d = min/kg, c= min/kg and a= min/kg and firewood min/kg. table values obtained in specific fuel consumption (sfc) and time spent in cooking (tsc) g of rice. treatment a, b, c, d and firewood. s/no treatments s.f.c (g) time (min/kg) a . b . c . d . firewood . . discussion . . density the density of the composites produced was found to increase down the treatment with a having average density of about . kg/cm , b= . kg/cm , c= . g/cm , d= . kg/cm which was the highest density recorded. gsc advanced research and reviews, , ( ), – from the research, it was deduced that increase in the amount of starch in a treatment leads to increase in the density of the briquette that will be produced and also influence compaction of the composites. . . energy content (caloric value) the energy content of the composites produced was determined using oxygen bomb calorimeter and the following values were obtained a= . calories/ gram for % sawdust and % starch, b which has the highest energy content was found to be . calories per gram, c= . calories per gram, d= . calories /gram which was the lowest caloric value recorded and these varied with the findings of [ ] who said that energy content of the composite briquette was found to be . mj/kg. these indicate that the energy content found in this experiment is higher than that of the above authors. . . specific fuel consumption (s.f.c) this was found to be lowest in treatment b with about . g produced from the mixture of sawdust and starch at and percent, firewood was found to be g and this correspond with the value obtained in treatment a, but all the rest of the treatment have better s.f.c than the firewood and this contradict with the finding of [ ] who reported that rice has a s.f.c of . g, though the quality of rice was not stated. it can still be conducted that this experiment has the higher value of s.f.c in cooking than what was discovered by [ ] the minimum quality of cassava starch required for briquette production, as reported by [ ] that it was impossible to produce any cohesive and stable briquette at a cassava content of %, % and % as they all simply fell apart after production and this is not in conformity with my finding. it was only treatment a that had such problem where the sawdust and the starch are in mixture of % and % respectively all the rest remain solid and this indicate that this level of binders are efficient. mc=mass of charcoal left is . g as constant, but it was reported by [ ] that the mass of charcoal (mc) after combustion of the composites was found to be negligible hence mc is assumed to be zero. this is in total disagreement with my findings because at any stage of the test some quantities of charcoal were left behind. . . time spent in cooking time spent in cooking g of rice are as follows for treatment a= min/kg, b= min/kg, c= min/kg, and d= min/kg where by the firewood was recorded with highest time spend in cooking with about min/kg. [ ] reported that briquette produced using starch only, rice about . min/kg, while in my research the lowest time was min/kg, though foreign rice was used in the test. . conclusion investigation of composite sawdust briquette as a source of fuel for domestic utilization was carried out in this research. it was observed that, composite briquette when used for cooking g of rice have lower specific fuel consumption than the firewood. also, the specific fuel consumption and time taken to cook certain amount of food depend on the type of food irrespective of the type of fuel used. in terms of the performance, it can be concluded that treatment b, c and d are better than fuel-wood. similarly, consideration factor such as desertification, soil erosion, flood, occur mostly as a result of exploitation of timber (forests), briquette provide a cleaner environment because it releases very low amount of co compare to fuel wood, it is also economical to produce, store and handle than the firewood. the researchers strongly recommend that  there is a strong need for public enlightenment about briquette production which will serve as a salient factor for forest conservation and environmental sanitation.  research should be geared in this area to explore different binders and material that can be converted into composites for energy application in our homes to reduce or solve the issue of energy crisis.  machines and equipment necessary for production of briquette should be provided at subsidized rate to make production of briquette in mass so that it can be available and affordable for the masses. compliance with ethical standards acknowledgments we appreciate the contribution of late dr. aa malami for his guidance and supervision of this research as well as the staff of sokoto energy research center biomass unit for their contributions throughout the laboratory work. gsc advanced research and reviews, , ( ), – disclosure of conflict of interest no any conflict of interest among authors references [ ] food and agricultural organisation. tropical forestry action plan fuel-wood energy. unasylva. : - . 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[ ] olorunnisola ao. briquetting rattan furniture waste for domestic and agro-industrial application. nigerian journal of renewable energy. ; ( & ): - . untitled- © nature publishing group nature vol. january international news credibility gap worries us energy office colin norman, washington after being deluged with dire warnings about the energy crisis that was sup- posed to hit the united states this win- ter, many americans are now beginning to wonder whether there is a crisis at all, or whether the whole thing is an elab- orate plot by the oil industry to drive up prices and profits. so far, there have gen- erally been adequate supplies of gasoline and heating oil, cities are still brilliantly lit at night by hideous advertising signs, and life is proceeding more or less nor- mally for most people. about the most tangible sign of energy shortages is that gasoline and heating oil have increased in price. according to william simon, director of the federal energy office, his biggest problem in the next few months is the growing public scepticism about the en- ergy crisis. he is anxious because such scepticism could lead to backtracking on conservation measures which have so far turned out to be remarkably effective in curbing demand, and that in turn could precipitate a full-blown crisis be- fore the summer arrives. and the prob- lem of maintaining public support will become even more difficult once arab oil again starts flowing into the united states. in fact, the administration is so concerned about the matter that presi- dent nixon made a radio address last weekend during which he warned that "if we permit ourselves to slack our ef- forts, to slide back to the wasteful con- sumption of energy, then the full force of the crisis will be brought home to americans in a most devastating fashion, and there will be no longer any question in anyone's mind about the reality of the crisis". the scepticism stems not only from the fact that there has been little dis- comfort so far in the united states, but also from a series of reports of record profits in the oil industry, rumours of tankers sitting outside ports waiting for oil prices to creep up before they unload their cargoes, and allegations that stor- age tanks at refineries are brimming with heating oil. but perhaps the most damaging blow to the credibility of the crisis is the growing public awareness of the fact that the government has been forced to rely almost exclusively on the oil industry itself for statistics about production and stocks of oil. as mr sil- vio o. conte, a republican congress- man from massachusetts, put it last week, that is like "putting a fox in to watch the chicken coop". the administration is thus beginning a campaign to assure the american pub- lic that the crisis is real, and that con- servation measures are still necessary. first, president nixon promised in his radio message that he will send a bill to congress which would impose a windfall profits tax on oil companies to force them either to turn over excess profits to the government or to invest them in exploration for new sources of energy. and second, the administration is spon- soring a bill which will, in nixon's words, "require the oil companies to provide a full and constant accounting of their in- ventories, their production, their costs and their reserves". and, in the mean- time, simon has ordered a full audit to be conducted on the companies' figures. those measures should, at least, help dispel some of the public distrust over the figures. but, although the government has been relying on industry data for its analysis of the energy situation, there is still good reason to believe that the shortages are real, and are not solely the product of an inspired public relations exercise by the oil companies. as s. david freeman, director of the ford foundation energy policy project, sug- gested last week, the companies have certainly been making a lot of money out of the situation, and the data they have supplied through the american petroleum institute may not tell the whole truth and nothing but the truth, but he suggests that they still indicate the need for gasoline rationing to be im- posed in the spring. and there is also good reason to be- lieve the administration's assertions that if the american public slackens in its conservation efforts, a severe crisis could still develop. for one thing, a variety of data supplied by the electricity indus- try, by the oil companies and by inde- pendent analyses all attest to the fact that conservation efforts have been re- markably successful in decreasing de- mand, even if the unusually warm weather in the last quarter of is taken into account. and for another, a lot of oil has been flowing into the united states through the embargo, and this is now beginning to dry up-and even if the embargo is suddenly lifted, it will take several weeks for the oil to reach united states ports. one of the most direct indicators of demand for energy is the amount of elec- tricity supplied to consumers. accord- ing to data produced by the edison elec- tric institute, at the end of last year, consumption of electricity throughout the united states was averaging about . % below that of a year previously. moreover, during the week ending on january , demand dropped by . %. compared with an expected increase of about %, those figures show a very substantial decrease in demand. in his radio address last weekend, president nixon also cited a sheaf of statistics to show that demand for other forms of energy has declined equally dramatically. consumption of gasoline in december was reduced by % below expected levels, for example, natural gas consumption was down by % com- pared with last. year, and he also re- ferred to a study in the north east which showed that some , house- holds had reduced their heating oil con- sumption by an average of % com- pared with last year, even after adjust- ments had been made for the warmer weather. the administration still reckons how- ever, that during the first three months of , supplies of oil will fa short of previous demand by about . million barrels a day, or about %. this must be accounted for either by ration- ing or by conservation measures. heat- ing oil is already being allocated to parts of the country which are especially hard hit by the oil embargo (in other words, it is being rationed at the wholesale level), and last week the federal energy office published details of a gasoline rationing plan which will be brought in if necessary, although no earlier than march. in any case, president nixon declared last weekend that he is opposed to gaso- line rationing, and will avoid bringing it in if at all possible. he said, for example, "if this voluntary cooperation (in reduc- ing consumption) continues, ... we can avoid gas rationing this spring ... and you can be sure that i will do every- thing in my power to achieve the goal of avoiding gas rationing." 	international news 	credibility gap
worries us
energy office international journal of engineering & advanced technology (ijeat) international journal of engineering and advanced technology (ijeat) issn: – , volume- issue- , december, published by: blue eyes intelligence engineering & sciences publication retrieval number: b / ©beiesp doi: . /ijeat.b .  abstract: in the experimental study, experiments has been done on an immediate infusion, single cylinder, constant speed, water cooling system vcr engine at injection pressures , and compression ratio of . using various blends. the effect of dual biodiesel blends and injection pressure were examined with various engine loads. lemongrass oil and methanol were blended with diesel at a variety of blend ratios for the purpose of investigation. presentation and release characteristics obtained from the systematic study reveals that brake thermal efficiency (bte) and brake specific fuel consumption (bsfc) of blend b (i.e. lemongrass % methanol % and diesel %) was higher than diesel. the emission of carbon monoxide (co), hydro carbons (hc), and carbon dioxides (co ) of dual biodiesel blends with better than that of diesel. it was identified that with increase in injection pressure from bar can be improving the performance analysis while reducing exhaust gas emissions. but increases the nitrogen oxides emissions. keywords: lemon grass biodiesel, engine performance test, emission test. i. introduction the utilization of the energy is growing day by day with the increase of industrialization and growth of modern civilization. [ ]the demand for biodiesel is increasing rapidly due to the small reserve of the fossil fuels and its better emission characteristics. [ ]-[ ]in concern of the society for the depleting world’s renewable energy sources with fuel and energy crisis led to the search for biofuels. therefore, an investigation on biodiesel has been chosen in this paper. the scope of this document is to evaluate the presentation and emission characteristics[ ] using different mixed blends ratio of lemongrass oils and methanol with diesel in a vcr engine. revised manuscript received on december , . m.saravanakumar*, asst professor department of mechanical engineering, aarupadai veedu institute of technology, vinayaka mission research foundation, chennai, india. email: saravanakumar@avit.ac.in m.prabhahar, associate professor department of mechanical engineering, aarupadai veedu institute of technology, vinayaka mission research foundation, chennai, india. email: mprabhahar@gmail.com org manikandan.v, ug student mechanical department, aarupadai veedu institute of technology, vinayaka mission’s research foundation,chennai, india. sajin mp, ug student mechanical department, aarupadai veedu institute of technology, vinayaka mission’s research foundation, chennai, india. gangadharan.k, ug student mechanical department, aarupadai veedu institute of technology, vinayaka mission’s research foundation, chennai, india. the objectives of this[ ]-[ ] experimental investigation are extraction of biodiesels (lemon grass oil and methanol) using transesterification process, determination of the properties of dual biodiesels, study of effect of the properties of blending of dual biodiesels and diesel, [ ]study of execution and emanation attributes of diesel motor using different blends of lemon grass oil and methanol with diesel. biodiesel as the most favorable alternate is presently produced from usually grown vegetable oils, such a coconut, palm and sunflower oils [ ]-[ ]]alternative fuels identified are biofuels having desirable fuel properties which are permitting them to replace the existing fuel completely. however, the researchers are working on different techniques give better solution to apply higher fraction of replacing biofuel in the existing diesel engine investigated the break thermal efficiency and[ ],[ ] check out to the merge misuse cooking oil % with waste cooking oil is marginally elevated than that of diesel at maximum solidity ratios. waste cooking biodiesel blends provide longer combustion pressure at maximum compression ratio due to higher explosion holdup, lower heat release rate and maximum rate of force rise when compared among diesel. brake pedal thermal efficiency of blends increase by way of increases in load. a. sanjid et al. investigated and concluded that mustard biodiesel showed favorable biofuel properties compared to few biodiesels. from the performance and emission analysis were also found hopeful. [ - ]as conclude that mustard biodiesel % and % be capable of be used in diesel engine devoid of modifications. srinivas et al. studied the performance as well as production individuality. table- i: lemongrass oil properties specific gravity . density . kg/m calorific value kcal/kg ( kj/kg) kinematic viscosity . ns/m flash point ˚c fire point ˚c cetane index performance characteristics of vcr engine using lemon grass oil and methanol mixed with diesel m. saravanakumar, m. prabhahar, manikandan.v, sajin mp, gangadharan.k performance characteristics of vcr engine using lemon grass oil and methanol mixed with diesel published by: blue eyes intelligence engineering & sciences publication retrieval number: b / ©beiesp doi: . /ijeat.b . ii. literature review k. rajan et al., [ ] conducted experiment with diesel blended with sunflower oil methyl ester which condensed the production of oxides of nitrogen at % and other unburnt hc,co emission are also decreased comparatively in different percentage of biodiesel blends in order of %, %, %. calorific value of this biodiesel is less hence bte is increased at % and bsfc is increased at %. iii. proposed setup and methodology the engine set up used is a computer based four caress, direct insertion, variable compression ratio (vcr), diesel engine, cooling of water system and single cylinder. from the test was showed at different loads resultant in constant speed. exhaust emission avl gas analyzer was used to compute emissions form wear out channel tube of the engine. from the experimental on vcr diesel engine complex is given in below finger. the thorough engine specifications are known below table. the vcr engine run by the diesel engine through dual biodiesel ratio blends as well as contrast with the diesel this is the characteristics and performance of the vcr. the scope of this presented paper is to evaluate the emission characteristics and performance using various mixed blends ratio of diesel and lemongrass oils with diesel in a vcr engine. the objectives of this experimental investigation are extraction of biodiesels, study of presentation as well as emission individuality of diesel engine with different blends of diesel and lemongrass oils by way of diesel the emission test is carried out during the performance test for different blends at different torque and blends. the prop is connecting with the exhaust pipe and the results were recorded by plotting the graphs for handbrake power to release limitations (co, hc, co , and nox). the value of emission parameters are measured by using avl gas analyzer. iv. results and discussion the experimental data from tests on vcr engine has been systematically studied. the result of blend ratio as well as fuel vaccination pressure at compression ratio of . has been presented by varying loads. three blends characteristics have been compared in the middle of diesel to understand the consequence of each parameter. the operation of the vcr diesel engine is found to be smooth for full load condition at different insertion pressures, compression ratio (cr . : ) without any operational difficulties for the dual biodiesel blends diesel fuel (i.e. l m , l m and l m ). fig. . bte for various blends brake thermal efficiency (bte) through percentage load for a variety of mixed blends is representing in above fig. . the bte of biodiesel is advanced than diesel especially at occupied freight situation. as of the graph it is evident that the bte is amplified through growing the blend ratio of lemongrass biodiesel. from the brake thermal efficiency of mixed blends for l m , l m and l m are . ( . %), . ( %) and . ( %) respectively higher than diesel ( . ). even the low calorific worth of bio diesel blends than diesel; proper fuel mixing provides quality combustion. this proves that dual biodiesel provides better brake thermal efficiency than diesel. fig. . exact fuel use for a variety of blends fig. . explains that the difference of brake specific fuel consumption (bsfc) with percentage load. as load increases the bsfc and reduces the dual biodiesels mixed blends. for the maximum full load condition in compression ratio . (cr . : ), the value of brake specific fuel consumption of mixed blends ratio b in l m , l m and l m showed for . , . and . kg/kw h whereas diesel ( . kg/kwh). international journal of engineering and advanced technology (ijeat) issn: – , volume- issue- , december, published by: blue eyes intelligence engineering & sciences publication retrieval number: b / ©beiesp doi: . /ijeat.b . fig. . carbon monoxide for various blends the difference of carbon monoxide through percentage load is shows in above fig. . from the plot load increase the carbon monoxide also increased is observed. the co of dual biodiesels mixed blends ratio b (i.e. l m , l m and l m ) decreases when compared to the diesel at compression ratio . for full load condition (cr . : ), the value of carbon monoxide (co) of mixed blends ratio b in l m is . %, l m is . % and l m is . % whereas diesel have . %. fig. . difference of hydrocarbons among load the difference of hydro carbons with percentage loads is shown in above fig. . from the plot as the pack increases the hydro carbon increases is observed. at filled freight state the hc of dual biodiesel mixed blends ratiob (i.e. l m , l m and l m ) decreases when compared to the diesel in compression ratio . (cr . : ), the value of hydro carbons (hc) of mixed blends ratio b . l m is ppm l m is ppm and l m is ppm whereas diesel have ppm. the emission has decreased by . % with b compared through diesel. fig. . difference of carbon dioxide through load co variation with its percentage of load rating is exposed in fig. . from the plan that the freight increases the co is also increased. the carbon dioxide of dual biodiesel mixed blends b (i.e. l m , l m and l m ) decreased when compared diesel at full load condition. as combustion product co is shaped when present is necessary quantity of oxygen there through the configuration of carbon monoxide. fig. . nitrogen oxides for various blends the effect of loads on nitrogen oxides is exposed in above fig. . the nox improved at fuel load condition for every mixed blends. each mixture blends ratio b (i.e l m , l m and l m ) are increased by nitrogen oxides (nox). for the compression ratio . (cr . : ) in maximum full load condition, mixed blends ratio l m gives ppm and diesel is ppm, l m gives ppm, l m gives ppm in the same maximum fuel load condition. from the outcomes, nitrogen oxides (nox) outflow is higher for double biodiesel mixed blends ratio than diesel. be that as it may, the nonedible oil with biodiesel has a necessary measure of nox generation. every one of the mixes give higher nox with contrasted with diesel. performance characteristics of vcr engine using lemon grass oil and methanol mixed with diesel published by: blue eyes intelligence engineering & sciences publication retrieval number: b / ©beiesp doi: . /ijeat.b . the normal temperature gas, the nearness of oxygen substance with fuel and habitation at full burden conditions with the blended mixes proportion burning caused higher nox outflows fig. . difference of brake thermal effectiveness with load break thermal efficiency at injection pressure of bar and bar for diesel and mixed blend (l m ) has been plotted in fig. . at various loads. the break thermal efficiency of blend at bar is increased by . % compared with bar.the fig. . shows the difference of brake exact fuel use with load. fig. difference of brake exact fuel use with load v. conclusion effects of blends on top of a solo cylinder vcr diesel engine characteristics run by dual biodiesels blend b mixed ratios (i.e.l m , l m and l m ) were systematically studied. the following are the conclusions from this study. dual biodiesel blends with % methanol, % lemon grass oil and % diesel with high injection pressure can be selected as an alternative fuel. this study provides the reliable data for researchers to choose suitable biodiesel combination. this study furnishes qualitative and quantitative information about the performance of engine with dual biodiesels. higher bte, lower bsfc, lower emissions are the superior qualities of the selected dual biodiesel combination. however, the nox intensity to be reduced by choosing the suitable technology. comparison of properties of the biodiesels such as viscosity, calorific value, helps the engineers to choose the various combinations of blends. performance comparison of blends with diesel engine proved that the biodiesel blends are good renewable source to meet energy crisis and to address the eco-friendly societal problem. this study augments the data base pertaining to biodiesels. references . h.e. saleh, “experimental study on diesel engine nitrogen oxide reduction running with jojoba methyl ester by exhaust gas recirculation,” fuel, vol. , no: , pp. – , . . y.c. sharma, b. singh, and s.n. upadhyay, “advancements in development and characterization of biodiesel: a review,” journal of fuel, vol. , no: , pp. – , . . k. rajan, and k. r. senthilkumar , “effect of exhaust gas recirculation (egr) on the performance and emission characteristics of diesel engine with sunflower oil methyl ester,” jjmie, vol: , no: , . . savita tomar, reena mishra, sarita bisht, sanjeev kumar, aman balyan, and mr.gaurav saxena, “optimisation of connecting rod design to achieve vcr,” int. journal of engineering research and applications, vol. , no: , pp. - , . available: www.ijera.com . pooja ghodasara, m. s. rathore, “prediction on reduction of emission of nox in diesel engine using bio-diesel fuel and egr (exhaust gas recirculation) system,” international journal of mechanical engineering, vol: , no: , pp. - , . . v. achuthanunni, b. baiju, “experimental investigation of a diesel-biodiesel fuelled compression ignition engine with exhaust gas recirculation (egr),” ijeat, vol: , no: , . . donepudi jagadish, puli ravi kumar, and k. madhu murthy, “research article performance characteristics of a diesel engine operated on biodiesel with exhaust gas recirculation,” ijaet, vol: , no: , pp. - , . . g. h. abd-alla, “using exhaust gas recirculation in internal combustion engines: a review,” energy conversion and management, vol: , no: , pp. – , . . d. agarwal, s. sinha, and a. k. agarwal, “experimental investigation of control of nox emissions in biodiesel – fueled compression ignition engine,” renewable energy, vol: , no: , pp. - , . . k. santoh, l. zhang, h. hatanaka, t. takatsuki, and k. yokoto, “relationship between nox and sm emissions from di diesel engine with egr,” society of automotive engineers of japan, vol: , no: , pp. - , . . v. pradeep, and r. p. sharma, “use of hot egr for nox control in a compression ignition engine fuelled with bio- diesel from jatropha oil,” renewable energy, vol: , no: , pp. - , . . dan scarpete, “romania.diesel-water emulsion, an alternative fuel to reduce diesel engine emissions. a review,” machines, technologies, materials, no: , pp. - , . . y. yoshimoto, et al, “reduction of nox, smoke and bsfc in a diesel engine fueled by biodiesel emulsion with used frying oil,” sae paper,vol: , no: , pp. - , . . kweonha park, inseok kwak, and seungmook oh, “the effect of water emulsified fuel on a motorway-bus diesel engine,” ksme international journal, vol: , no: , pp. - , . . n. samec, b. kegl, and r.w. dibble, “numerical and experimental study of water/oil emulsified fuel combustion in a diesel engine,” fuel, vol: , no: , pp. - , . . k. kannan, and m. udayakumar, “nox and hc emission control using water emulsified diesel in single cylinder diesel engine,” arpn journal of engineering and applied sciences, vol: , no: , pp. - , . . r. sathiyamoorthi, and g. sankaranarayanan, “experimental investigation of performance, combustion and emission characteristics of neat lemongrass oil in di diesel engine,” international journal of current engineering and technology, vol: , pp. - , . http://www.ijera.com/ international journal of engineering and advanced technology (ijeat) issn: – , volume- issue- , december, published by: blue eyes intelligence engineering & sciences publication retrieval number: b / ©beiesp doi: . /ijeat.b . . sangeetha.krishnamoorthi, et al, “performance and emission characteristics of a diesel engine using preheated cashew nut shell liquid (cnsl)-diesel blend,” journal of chemical and pharmaceutical sciences, vol: , no: , pp. - , . . k. sivaramakrishnan, "investigation on performance and emission characteristics of a % % % % % % % variable compression multi fuel engine fuelled with karanja biodiesel–diesel blend," egyptian journal of petroleum, vol: , no: , pp. - , . . l. prabhu, s. satish kumar, a. anderson, and rajan k, “investigation on performance and emission analysis of tio nanoparticle as an additive for bio-diesel blends,” journal of chemical and pharmaceutical sciences, no: , pp. - , . authors profile m.saravana kumar, profile asst professor department of mechanical engineering aarupadai veedu institute of technology vinayaka mission research foundation. saravanakumar@avit.ac.in. prabhahar .m, associate professor department of mechanical engineering aarupadai veedu institute of technology vinayaka mission research foundation mprabhahar@gmail.com manikandan. v, ug student mechanical epartment, aarupadai veedu institute of technology, vinayaka mission’s research foundation, deemed to be university. sajin mp, ug student mechanical department, aarupadai veedu institute of technology, vinayaka mission’s research foundation, deemed to be university. gangadharan, eug student mechanical department, aarupadai veedu institute of technology, vinayaka mission’s research foundation, deemed to be university. mailto:saravanakumar@avit.ac.in statement of ownership, management and circulation required by act of october , : section , title , united states code . date of filing: october , . title of publication: ps . frequency of issue: quarterly in february, may, august, november. . location of known office of publication: new hampshire avenue, n.w. washington, d.c. . location of the headquarters or general business offices of the publishers: new hampshire avenue, n.w. washington, d.c. . names and addresses of publisher and editor: publisher: american political science association new hampshire avenue, n.w. washington, d.c. . editor: walter e. beach same address as above. . owner: american political science association new hampshire avenue, n.w. washington, d.c. . known bondholders, mortgagees, etc.: none. . the purpose, function and nonprofit status of this organization and the exempt status for federal income tax purposes have not changed during the preceding months. . extent and nature of circulation: a. total number copies printed b. paid circulation . sales . mail subscriptions c. total paid circulation d. free distribution by mail, carrier or other means e. total distribution (c + d) f. office use, left-over, unaccounted, spoiled after printing , , g. total , , ps fall average no. copies each issue during preceding months , none , , , actual no. copies single issue nearest to filing date , , , , xdne c/lmerican tj olitical science c/issociation announces th annual congressional fellowships - for political scientists for journalists program qualifications one-month orientation period, followed by numerous conferences with members of congress and others during the remainder of the year. nine months working as a full-time aide to members of the house and senate, or on the staff of a congressional committee. opportunities for research. f o r p o l i t i c a l s c i e n t i s t s completion of ph.d. in political science within the last ten years (or near completion). (faculty on sabbatical leave encouraged to apply.) for journalists bachelor's degree and between two and ten years of professional experience in news- paper, magazine, radio or television reporting. stipend: $ , . . small allowance for children. applications must be submitted prior to december , . awards will be announced by march , . preference will be given to candidates without extensive experience in washington, d.c. fellows are expected to be in washington from early november to mid august. further information and application blanks may be obtained from: congressional fellowship program the american political science association new hampshire ave., n.w. washington, d.c. supplementary empirical teaching units in political science: new computer related instructional materials whereby students learn important substantive topics in american politics as they learn methods of analysis. seven setups: american politics are available now for class use . voting behavior: the election by bruce d. bowen, c. anthony broh, charles l. prysby. . political socialization across the generations by paul allen beck, jere w. bruner, l. douglas dobson. . political participation by f. christopher arterton, harlan hahn. . the supreme court in american politics: policy through law by john paul ryan, c. neal tate. . u.s. energy, environment and economic problems: a public policy simulation by barry hughes. . representation in the united states congress: by ray a. geigle and peter j. hartjens. . the dynamics of political budgeting: a public policy simulation by marvin k. hoffman. ps fall four setups: cross-national and world politics will be available for class use, winter . comparative voting behavior by herbert b. asher, bradley richardson. . the budgetary process in cross-national perspective by john creighton campbell, john m. echols. . conflict in the middle east: a public policy simulation by karen ann feste. . are political values really changing? by charles taylor. each setups 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"instructor's manuals are available for these texts. college division mcgraw-hill book company avenue of the americas new york, n.y. • • • • • • • • • • • • • • • • i publications of the national center for public service internship programs the directory of public service internships is designed primarily for graduate students, post-graduates and mid-career professionals. it is a comprehensive guide to internships and fellowship opportunities throughout the united states. each entry provides complete information about program objectives, re- cruitment, selection procedures, admission requirements, and remuneration. the directory of washington internships. is a guide to the many internship opportuni- ties available in the nation's capital; contain- ing a description of each program, informa- tion about living and working in washington, and a bibliography of related resource infor- mation. especially useful to undergraduates and graduate students. the directory of undergraduate 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edition of this leading study of politics in france appeared, that country has gone through one national referendum, one parlia- mentary election, one presiden- tial election, and a rather drastic restructuring of its party system. this new third edition will help students understand these important events in both their new and old contexts. professor ehrmann was also prompted to write this revision by the continuing, impressive output of studies on modern french pol- itics. ehrmann critically reviews the most important discussions and indicates major areas that remain open for further investigation. paper approx. pages august $ . tent. cases in comparative politics third edition james b. christoph indiana university bernard e. brown city university of new york extensively revised and updated, this new third edition of cases in comparative politics features eight case studies—two each on britain, france, germany, and the u.s.s.r.—that examine foreign and domestic policy-making in those countries. all of the cases were written by specialists expressly for this volume. new cases on university reform in france, codetermination in west germany, and ostpolitik have been added to this edition, and important new material has been incorporated into all the other cases. an introductory section deals with the case method in comparative politics and the concept of decision-making. paper approx. pages august $ . tent. coming later this f a l l . . . power and inter- dependence world politics in transition robert o. keohane stanford university joseph s. nye harvard university transnational politics—a con- temporary theoretical approach to world politics, applied to four historically-extensive case studies. cloth approx. pages november $ . tent. also available in paperback: $ . tent. felony justice an organizational analysis of criminal courts james eisenstein pennsylvania state university herbert jacob northwestern university a comparative analysis of felony dispositions in chicago, detroit, and baltimore. cloth approx. pages november $ . tent. also available in paperback: $ . tent. ps fall other recent publications. the basics of american politics gary wasserman medgar evers college, cuny with ed beard and marsha hurst a new, brief and inexpensive introductory text. simply and straightforwardly, this lean vol- ume deals with the most elemen- tal structures and functions of american government. the theme of politics as a game uni- fies the book and focuses atten- tion on the dynamic competition for power and values. emphasis is placed on the effects of, and our constant involvement in, politics. paper pages $ . american government readings and cases fifth edition peter woll brandeis university american government— now available in an updated fifth edition—focuses on issues that are central to an understanding of the governmental process. the new edition provides the same excellent coverage of con- stitutional cases and historical and analytical background materials as the earlier editions. but % of the readings in this edition are new; they deal with contemporary problems and the stresses that have been placed on the political system in the s. a new instructor's manual is also available. paper pages $ . u.s. foreign policy and world order james a. nathan james k. oliver both at the university of delaware nathan and oliver's outstanding new foreign policy text offers: ( ) a detailed, comprehensive overview of u.s. foreign policy since world war ii; ( ) a system- atic, unifying theme: the evolu- tion of military force and the threat of force as the primary instrumentality of american foreign policy; ( ) a synthesis of the political-strategic and eco- nomic elements of u.s. foreign policy; and ( ) an integrated analysis of foreign policy and domestic institutions. paper pages $ . politics in the american states a comparative analysis third edition herbert jacob northwestern university kenneth n. vines suny buffalo the leading text in the field of state politics has been substan- tially revised and rewritten for its new third edition. it features a new chapter on the regulation of the environment, a new chapter on federalism, five new authors (all chapters are either new or re- written), and a greater emphasis on lucid explanation rather than statistical analysis. cloth pages $ . political change in the metropolis john j. harrigan hamline university political change in the metropolis is a new text that integrates coverage of central - city, suburban, and metropolitan- level politics, as well as the politics of federal involvement in urban affairs. one major analyti- cal theme—the bias of political change—draws the author's material into a coherent and logi- cal argument. thorough cover- age of machine politics, ethnic politics, the political reform movement, and community con- trol is provided. paper pages $ . what is a'caucusite"? the following are recent candidates sponsored by the caucus for a new political science: peter bachrach stanley hoffmann james david barber p h i l i p e. jacob christian bay hans morgenthau walter dean burnham jewel prestage james macgregor burns james w. prothro kenneth dolbeare inez smith reid murray edelman dankwart a. rustow richard falk mulford q. sibley betty glad irene tinker charles v. hamilton marvin zonis i){ you lead. thex/i wofdk, and that o£ othex "caucu&itte," you. will diicovex no one. aul-con&uming tmtth tunning throughout. in&tead, you. will lijnd di&- ieaencti o& methodology, ofi ideology, ofa conclu&ijon, ofi phtecju.pta.on. the. unifying facto*. it> devotion to fitepomible. •idiolaaakip and to the. light oi alt to pauue acholamhip in ushatevzn. utay thzy choo&e.. injlt, ytax'i caucua candidate fan. apsa o^ice. aha/ie. the. agnzement to di&agizz, betieving that it aj> vital to the. e.xpan&ix>n o£ knowledge, and the. axtlzulation oi a new p o l i t i c a l science. that i& why the.y atie. caucui candidate. that i& why we usig& you to vote. fan. them. president-elect: frances fox piven vice-president: hayward r. alker, jr. philip converse secretary: robert r. alford treasurer: dina a. zinnes council: benjamin r. barber marguerite r. barnett amy bridges samuel hendel chun-tu hsueh alfred g. meyer bertell ollman donald van atta *term coined by heinz eulau, letters to the editor, pj[, summer, , p. . cnps american political science association new hampshire avenue, n.w. washington, d.c. postmaster: if undeliverable, even after forwarding, return to executive director american political science association new hampshire ave., n.w. washington, dc. return postage guaranteed second class postage paid at washington, dc. cellular energy crisis: particulate hitchhikers damage mitochondria a volume | number | october • environmental health perspectives environews science selections cellular energy crisis particulate hitchhikers damage mitochondria one of the body’s most important processes—energy production by mitochondria in the cell—can be significantly disrupted by exposure to ultrafine particulates, according to a team of researchers from the university of california, los angeles, and the university of southern california [ehp : – ]. furthermore, the researchers say, the primary culprits are sub- stances that are attached to particles. these findings provide the first insights into the specific mechanism by which ultrafine parti- cles, increasingly recognized as environmental villains, damage mitochondria, says principal investigator andre nel. the researchers conducted a series of experiments that evaluated the effects on mouse liver mitochondria of either diesel exhaust par- ticles (deps), ambient ultrafine particles collected in the los angeles area, or engineered nanoparticles with no attached chemi- cals. using the deps and ultrafines collected in los angeles, the team isolated organic “hitchhiker” substances such as polycyclic aro- matic hydrocarbons (pahs) and quinones that had attached to the particle cores. these chemicals were tested for a variety of effects on cells and mitochondria. among the adverse effects observed were mitochondrial struc- tural decomposition, mitochondrial swelling due to increased mem- brane porosity and rupturing, increased production of free radicals, and induction of cellular death. although some of these effects were dependent on the presence of calcium, others were caused by direct damage to the mitochondrial membrane. the mitochondrial effects varied with the specific hitchhiker substances tested. for instance, polar fractions high in quinones were much more potent in inducing cell death, whereas aromatic compounds high in pahs had a more moderate effect, and aliphat- ic compounds had no apparent effect. even within a class of compounds, not all substances proved to be equally destructive. for instance, among quinones, phenan- thraquinone and , -naphthoquinone caused mitochondrial swelling, while anthraquinone did not. this difference may depend on the ability of particular quinones to participate in reactions that generate reactive oxygen species (ross), unstable compounds that can quickly react with and damage other substances. the team speculates on the biological mechanism behind the observed effects, laying the groundwork for future research. in the case of quinones, they suggest that the substances may redirect elec- tron transfers in the inner mitochondrial membrane to molecular oxygen, thereby generating ross that can damage the mitochon- dria as well as exert proinflammatory effects. these effects could be important in the exacerbation of asthma. regardless of the specific mechanism, the consistent culprits in damaging mitochondria were the organic sub- stances attached to particle cores. in contrast, engineered polystyrene nanoparticles with no organics attached had no apparent effects, leading the team to speculate that the small size of engineered nanoparticles may not be solely responsible for inducing mitochondrial and cellular dam- age. this is of considerable interest to the burgeoning field of nanotechnology, where there is concern that nanoparticles may be toxic based on small size alone. the researchers acknowledge that smaller particles tend to penetrate better than larger particles and possi- bly are more bioavailable, due to their higher surface-to- volume ratio. these characteristics may allow organic chemicals that are attached to particle surfaces to better penetrate tissues than if they are not carried along by tiny transporters. –bob weinhold measuring by hand arsenic picked up from the playground several nations today ban or severely restrict the use of wood preserved with chromated copper arsenate (cca), but many existing structures still remain—for example, about % of existing u.s. single-family homes and % of public playgrounds incorporate cca-treated wood. in recent years, scientists have studied how arsenic leaches from cca-treated wood, but they have only inferred exposure levels from measurements of arsenic concentra- tions in soil and sand near treated wood structures. in this issue, elena kwon of the university of alberta and col- leagues report on direct measurements they made of arsenic on the hands of children playing in playgrounds, some with cca-treated wood structures and others without [ehp : – ]. the team reports that although playing on treat- ed structures increases the amount of arsenic on children’s hands, washing the children’s hands after playing may be enough to avoid the health risks associated with cca. for several decades, cca-treated wood was widely used in the united states, canada, and other countries for playground equip- ment, fences, and backyard decks. bans and restrictions on the use of cca-treated wood have been driven largely by concerns that treated wood could release chromium and arsenic, posing risks to human health. especially vexing was the possibility that children who contacted cca-treated wood structures were, because of their propensity for hand-to-mouth contact, especially at risk for ingesting arsenic. although touching treated wood will not liberate the - to energy drains. new research conducted on mouse liver cells shows that toxicants that “hitchhike” on particulates severely interfere with the ability of mitochondria (framed, above) to produce energy. source: li n, sioutas c, cho a, schmitz d, misra c, sempf j, et al. ultrafine particulate pollutants induce oxida- tive stress and mitochondrial damage. environ health perspect : – ( ). science selections environmental health perspectives • volume | number | october a c re at as -milligram dose of arsenic that is fatal to humans, ingesting lower doses of the substance has been linked to several can- cers and other ailments. the scientists measured arsenic on the hands of children who visited public playgrounds in edmonton, canada, over the period – august . they tested all children who visit- ed the playgrounds during randomized observation times and whose parents allowed them to participate in the study. the children averaged . years of age and spent an average of . hours on the playground. when each child was finished playing, his or her hands were rinsed for minute in a ziploc bag of deionized water. the water and any soil/sand rinsed from the child’s hands were analyzed separately in the laboratory for arsenic content. the team also collected soil/sand samples from each playground; samples from near the structures provided a measure of the arsenic that had leached from the wood, while those taken far from the structures indicated how much arsenic was present naturally. in comparing playgrounds with and without cca-treated wood structures, the team found no statistically significant difference in the amount of arsenic in the soil/sand samples or in the soil/sand washed from the children’s hands. however, children who had played in the treated-wood environment had an average of . micrograms of soluble arsenic rinsed from their hands—more than five times as much as the children who did not play on treated structures. epa research indicates that ingestion, rather than inhalation or dermal absorp- tion, is the primary route of exposure related to arsenic-related ailments. children aged – typically ingest about half of whatever they collect on their hands. but even assuming that the chil- dren in the study managed to ingest all of the arsenic on their hands, their average dosage was less than the average canadian child’s daily dose of arsenic through food and water (about . micrograms per kilogram body weight). the scientists also found that the first rinsing removed most of the arsenic from the children’s hands. that could be the prescription for parents whose chil- dren frequent playgrounds with treated- wood structures—and who want to play it safe. –scott fields picked up on the playground. arsenic from treated wood play structures is transferred to children’s hands, but washing can remove most of it. 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d f c f e f d f e e c e f d e e f e f e e e c e> >> >> setdistillerparams << /hwresolution [ ] /pagesize [ . . ] >> setpagedevice wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ international journal of soft computing and engineering international journal of recent technology and engineering (ijrte) issn: - , volume- issue- s , august published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s  abstract-: the development growth of any nation is based on making a balance between power generation and its supply. but unfortunately every year pakistan show the expansion curve between supply and demand. so the gap can be overcome by utilizing the existing renewable resources, which have the capacity to fulfill future demand. the scientific proof has been mounting for many years to use renewable energy (re) resources. one of these shared resources is wind energy that presently seems like the primary emerging supply source of energy around the globe. the wind is such type of natural resource that capable to supply the unstoppable energy from wind turbines. the wind energy can play a significant role to supply economical and environmentally friendly energy. the wind energy only needs basic information about wind conditions for windmills installation at a localized place. so the world bank conducts the study of each wind speed information obtained from the installed station in the selected region of the world including pakistan for an extent of years. in this research, the wind availability is being observed for the coastal megacity, of pakistan on the basis of world bank data. keywords: wind energy; windmill installation; location observation; wind potential; world bank data. i. introduction electricity plays a vital role within the socio-economic growth and collective prosperity of any country. the energy is the basic necessity for human growth. nowadays, low production of electricity may be a major problem in pakistan, which directly limits the development of the state. pakistan’s population doesn't have any reliable source of electricity within the rural areas and concerning – hours load shedding in urban areas. although the state of pakistan continually shows a deficit within the typical resources, however, no progress was conjointly being created within the alternative resources. therefore, it's advanced to utilize these natural assets so as to satisfy the demand-supply gap. pakistan is facing severe energy failure issues, with power shortage a day, accounting for financial losses. the revised version manuscript received on august , . sabir ali kalhoro, department of electronics engineering ned university of engineering and technology university karachi, pakistan(email: sabir es @gmail.com) muhammad ali noman, indus university karachi, pakistan(email: ali.noman@indus.edu.pk) maqsood ur rehman awan, department of electronic engineering, dawood university of engineering & technology, karachi, pakistan(email: maqsood.rehman@duet.edu.pk) engr. tufail ahmed, department of electronics engineering mehran university of engineering and technology jamshoro, pakistan(email: tufail.waseer@faculty.muet.edu.pk) shafique ahmed soomro, indus university karachi, pakistan(email: shafiq.soomro@indus.edu.pk) muhammad faisal, indus university karachi, pakistan(email: m.faisal.shaikh @gmail.com) electricity generation capacity is significantly inadequate than the peak demand. the global issue due to the use of conventional resources are utmost suffering toward the crisis and therefore a substantial increase within the utilization of other alternative energy resources is globally discovered. pakistan is among those nations that suffer an acute energy shortage [ - ]. energy crisis and at a similar time is recognized jointly of the quickest growing marketplace for the assessment of alternative energy potential. the daily power requirement is above , mw whereas a daily shortfall of – mw [ ] is discovered. the pakistan coastal belts hold adequate views for the assessment of alternative energy potential and are probably at the viable locations for launching windmills. also, some district of punjab and a few northern areas of west region are suitable for putting in place tiny wind farms. the pakistan meteorological department (pmd), alternate energy development board (aedb) and government have accompanied a variety of task to assessing alternative drive in numerous regions of the country. the radical analysis for the wind speed available in the selected areas is very much significant for consistent assessments of alternative energy. the development growth of any nation is based on making a balance between power generation and its supply. today’s generation of energy successively depends on the accessibility of renewable and non-renewable power resources. non-renewable power sources are commonly measured in a state of depletion region especially where there is developing nations are located. moreover, the adverse effects of fossil-fuel-based energy are leading to environmental deterioration and co emission. therefore, the re resources not merely help in decreasing the fossil-fuel consumption however additionally reduces the possibilities of green-house impact. the renewable energy resources are slowly and gradually replacing the fossil fuel-based energy into the non-ending and eco-friendly supply of energy as a re. this is accessible for the humanity that gives a wide supply of energy in the speedy replacement standard of existing energy sources [ – ]. with ever-increasing environmental and socio-economic awareness, government and legislative authorities, around the globe, are involved to consider the pollution-related challenges and parameters that influence the energy pattern. therefore, renewable energy resources, like, wind, solar, and hydro are used to generate electricity to cut back wind energy status and potential assessment across coastal mega city, of pakistan sabir ali kalhoro, muhammad ali noman, maqsood ur rehman awan, engr. tufail ahmed, shafique ahmed soomro, muhammad faisal wind energy status and potential assessment across coastal mega city, of pakistan published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s fossil-fuel-related environmental considerations. the planet desires swift, equitable, vital, and effective climate action on this stage. the scientific proof has been mounting for many years to use re resources. one of these shared resources is wind energy that presently seems like the primary emerging supply of energy around the world. the electricity generated from the wind arrangements can be a necessary replacement for typical fossil fuel-based resources by completely diverse modalities. though the initial cost of putting in an electrical system is comparatively high, however, the running value is incredibly low. in this, research the environmental impact and extended challenges of the technological example for the event of wind energy technology with specific relevance are discussed. electricity is usually a vital ingredient for the growth of a country. the deficiency touches expansion level of the country by cause’s anxiety among the buyers. the energy shortage in karachi, which is the most important town and economic hub of pakistan is extremely impeding the progress of the town. presently the energy deficit within the town is around mw. the proposed research offers an analytical study of little residential windmills to scale back the energy shortage in karachi. the wind potential carried to indicate the influence of the incorporation of little residential windmills in the power grid. the results show mwh electricity is being saved by % of domestic buyer’s equipped with little windmills. the paper conjointly discusses the potential resistance within the introduction of little residential windmills in the domestic sector. the potential compensations to the utility and buyers also are conferred during with the usage of the windmills [ - ]. the existing research highlight the country electricity profile state of affairs concerning with the wind energy potential. the characteristics and efficiency of the foremost wind passageway within the southern part of sindh especially karachi of pakistan. pakistan has around kilometers coastal line for the wind energy potential, however, during this research, the foremost appropriate wind corridors of the southern part of the country are being observed. the observed region conjointly tried to prove the windy area in the favorable demand of the country. moreover, future perspective, challenges and potential are being mentioned for the energy necessity expansion contribution. the wind is such type of natural resource that capable to supply the unstoppable energy from wind turbines. the wind energy can play a significant role to supply an economical and environmentally friendly energy. the wind energy only needs a base stand of wind conditions at the localizing under study. the wind characteristics of jhampir and gharo (district thatta sindh, pakistan) are investigated for the traditional observation of the energy potential. the world bank conducts the study of each -minutes wind speed information obtained from the installed station in the selected region of the world including pakistan for an extent of years. the hourly, monthly, seasonal, and yearly investigation is performed by suitable measured wind speed information. the different parameters are determined numerically and technically for wind energy observation. wind energy is a rising market in pakistan that attract the researcher as well as a business person. while wind generation was slow to enter the country's energy market however the past six years have seen incredible growth within the wind generation sector. the three wind farms grid is interconnected to the national grid tributary over a hundred and fifty mw. besides these comes, several other alternative projects come are at other different stages near completion. this has been due to the strengthening infrastructure, means process of proposals, foreign and personal sector’s investment and engaging re policy for the wind generation develops. if all comes mentioned reach industrial operation, wind generation can contribute a minimum of a pair . gw electrical power and achieves its aim % contribution of re within the national energy by . the efforts for sensible expedite the expansion of the re sector in the residential sector. the government has recently determined to require an opening from any new wind generation comes stating that within the current scenario. the wind power technologies are suitable and feasible for pakistan, analyses research have declared. rather than sidelining the quick-growing energy technology by the govt for the re development in the region. the amendment of government, its methods and policies to encourage economically and price-effective investments within the sector, that is wind generation. higher programming, energy, and risk management techniques are required to extend wind generation within the energy combine [ - ]. wind power is that the most numerous supply of re that is capable to equate the conventional source power generation. the wind energy is sustainable, and green source of energy offered in the selected constituency of countries. the proposed research estimates the potential of wind energy choices to fulfill a gap between supply and demand in the metropolis, where the policymaker aims to discuss the feasibleness of the planned comes. the target is to achieve renewable energies that supply free of energy to the metropolis in an easy way. the approach is predicated on the assets principle that a town ought to initial plan to meet its demand from its own resources so as to extend its alternative energy that supports the native economy and minimize the prices and losses related to the fuel, and transmission and distribution of electricity. the objective is to combine a pair of % energy need from the wind resources with the national grid. also, the planned to syndicate the existing energy into the free supply by wind resources. the outcomes of this analysis are based on the world bank data that involve re potential in the belt of geographical availability of wind. . . global to pakistan development status of wind energy growth globally, fast increasing power demand, enhance the ability prices and pursuit to attenuate the pollution of the atmosphere because of the conventional energy resources have excited to take advantage of renewable energy sources. surrounded by different renewable energy resources the wind energy is the most leading and essential variety of power generation. being, a pollution-free, endless and cheap sources. the wind is the quickly raising re sources in each developing and developed countries. in pakistan, many research is conducted within the field of re that consists of international journal of recent technology and engineering (ijrte) issn: - , volume- issue- s , august published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s the possible study in their exploitation. it’s significantly necessary to require attentive relating to power generation from wind potential. as the speedy energy crises like oil and their prices in , many policymakers, engineers, and scientists were taken interest and appraisals relating to free energy sources like wind potential. the whole put in wind energy capability of the globe since – . pakistan is among the countries that face the increasing energy crisis. pakistan fights with a variety of economic, political and social problems, the growth from existing fuels based system to the re isn't so simple. pakistan has been gifted with the wind source however they need steps for exploitation. the re technology will not only penetrate the market but overcome the joblessness. the highlights of the past attract toward the development of the usual energy crisis. up to , no single re power grid existed however currently the case has modified significantly and wind farms conducive to the national grid are a reality at this time. many wind energy farms are inaugurated and lots of others are in pipeline. the government policy concerning wind generation systems has recently modified once surprising developments within the wind sector improvement for the wind generation combine the optimistic estimations. it is estimated that by , one-fifth of the electricity demands of the world are often met by wind energy. this is not solely environmental however economic advantages for all countries to incorporate wind generation as clean, re supply. pakistan is utilizing various re resources for energy empowerment, wind energy is one of them. the wind energy comes won't solely useful in reducing ghg emissions however conjointly decrease the billions of rupees on trading fossil fuel. the wind energy resource of southern sindh is rich at the gharo and jhampir, according to the study. the cost-effective analysis of wind generation in the southern sindh have already done by planner through the different categories of windmill installation. the national renewable energy laboratory (nrel), usa state that pakistan has a large quantity of wind potential nearby gw. pakistan will complete wind map and corridors in the southern sindh by windy areas that reach – m /s wind speed. the coastal belt of sindh has the capacity to generate gw of electricity. pakistan will need an enhanced ability to supply safe and secure viable power, which diminish international circumstances. it additionally offers commercially good opportunities to come back across the definite demands for energy services in the mean for rural areas as well as developing regions. further, manufacturing employment due to native trade for the commercial aspect. the consistent international standards, essential to construct less difficult wind potential classification comprehensively, the winding passageway for wind utilization so as to suit alternative energy plant, and it's a collective compute for putting in the windmill unit in wind regions [ - ]. . . energy status in pakistan according to the research, approximately . billion persons reside while not have electricity worldwide; from that, the developing ten countries have %, one of them being pakistan. although the fact that the energy crisis has troubled pakistan since its birth in , this incomprehension problem confessed the development door of country. from domestic resources might meet solely two-third of electricity demand. because the population expanded significantly, with annual growth rates quite % throughout the last decade, pakistan was concerned to reduce the gap between demand and offer. the energy consumption per capita was additionally grown from kwh in to kwh in , the vaster gap between offer and demand. so it was very important to balance the energy gap that absolutely growing the economy rate. far along on, the s, the energy zone received abundant consideration, the purpose is to accelerate the generation rate. in , the industrial buyers were already suffering regulatory crises due to deficiency of energy run, the government declared a % increase within the industrial tariff from – rupees per kwh to rupees per kwh. also, the rate of local use was additionally magnified from – rupees per kwh to – rupees per kwh. k-electric, the most electricity supplier to the million individuals of the urban center, was then suffering an amazing monetary crisis and expressed its inability to produce electricity exploitation. the main efforts to advance pakistan's energy sector initiated within the eighties country, while the power shortage weakened the possibilities of economic development within the country. to deal with this crisis, the government of pakistan in enacted its first non-public power policy. this policy was geared toward non-public investors to the facility sector. the requirement for re was accomplished by researchers and studies on resource potentials had started in the eighties. initially, there was an absence of complete and reliable information on wind energy resources in pakistan. the restricted information collected by the wind instruments to see technical and economic accessibility of wind generation comes. yet, the potential of a site for harnessing wind energy shaped. usually, the particular power generation is way lower because of several factors and may hit as low as mw, whereas the demand varies between , mw (summer) and , mw (winter). the country has four provinces particularly, punjab, khyber pakhtunkhwa (kpk), sindh and balochistan. punjab is the largest province (population-wise) with or so fifty-six of the country's total population. there’s a growing demand for energy during this province. with relevance wind energy, it doesn't supply abundant potential except maybe at its kalarkahar region that is – km wide and km long. kpk is home to a twelve-tone system of the overall population of pakistan. this province is that the smallest province by space, however, is that the most climatically diverse; with deserts, forests and tundra’s all settled at intervals. some areas of this province are known for hybrid power systems like solar-wind-hydro and there's a good potential for tiny scale turbine installations [ - ]. ii. model pakistan is the country in the world where there are great wind energy potentials. electricity, in large quantities, can be produced by taking advantage of the available renewable energies. wind energy status and potential assessment across coastal mega city, of pakistan published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s the wind energies of pakistan especially karachi have been investigated with the help of available world bank data. the wind energies of the selected regions give the commendable measurement which can be exploited to generate the great amount of wind energy. the require parameter like turbulence intensity, min. wind speed, max, wind speed, mean wind speed & wind speed standard deviation have been studied to extract the wind energy. the world bank calculates the wind potential across karachi on the basis of the above-given parameter. these parameters play a vital role for wind speed measurement. according to the analysis of the world bank data, these parameters are based on wind calculation. the world bank put this parameter on the calculation of different cities especially karachi. the world bank choose this parameter to calculate the wind potential of pakistan as shown in eq. to eq. . iii. experimentation the world bank has established a wind speed based project in order to find the wind speed across different cities of pakistan. the world bank has set number station for the calculation of the re power across different countries as well as pakistan. pakistan has got so many numbers of substations through the different cities as a part of the global effort. the karachi is the megacity of the pakistan and world bank select this city for the investigation of the wind data reported in this paper. the world bank set the wind station for the wind potential measurement in the whole scenario. the project is installed at the “ned university of engineering and technology karachi” for the re potential measurement along with the supported team management. the data of the different parameter is acquired in a period of every ten minutes. this data is continuously getting from to for wind power observation. iv. result the main results as regards the require parameter like turbulence intensity, wind speed minimum (wsmin), wind speed maximum (wsmax), mean wind speed (wsmean) and standard deviation wind speed (wssd) have been studied to extract the wind energy. the wind result shows the replica of the existing available wind into the electric power in the daily, hourly, monthly and yearly trend. the python software is used to indices the result to access information in a very important piece of the pandas statistic tools. the benefits of indexed information generally still apply, and pandas provides the time series detailed operations for the pictorial form. as a result of pandas was developed mostly in tools for input material. the pandas have a variety of online obtainable sources, like google finance, yahoo finance, and etc. here we are going to load google's for the program operation. the pandas use to find the overall wind speed parameter like wsmin, wsmax, wsmean, and wssd for karachi in each kind of trendline has experimented as shown in figure. . figure. . the wind speed parameter for karachi for wind speed trendline is experimented. the wind speed parameter has experimented in a weekly count. the weekly count is best for the wind speed observed for the period of jan to april . the python gains some insight into the dataset by visualizing it. this is followed by intrigue the data. the python software will gain command by resampling the information as presented in figure. . figure. . wind parameter for the karachi are experimented in a weekly count. the weekly count for the wind speed are observed for the period of jan to april . after the weekly count, the python is ready for the mean hourly count here the wsmin, wsmax, wsmean & wssd are observed as same as in the weakly count but the only difference in the parameter of wind form direction. this change in the trend as you may expect the seasonal trend of the wind speed. the perform of the speed is the difference in the summer and winter as selected season varies from week to week in a model. wherever the python has a tendency to explore further in a very minute period of time to gives the output as publicized in figure. . international journal of recent technology and engineering (ijrte) issn: - , volume- issue- s , august published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s figure. . the wind parameter for the karachi are experimented in a mean hourly count. the mean hourly count for the wind speed are observed for the period of jan to april . figure. . the periodic trend of wind parameter for the mean hourly count is experimented. the mean hourly count is investigated from jan to april . the irregularity in the results obtained in figure. and figure. because the world bank obtain data by every minutes and there is almost that time period in which data is zero at a different time it shows irregularities. there are many time slot in morning and evening which give zero results so the gap shows the variances in the obtained result as shown in figure. - . the hourly trend of the model shows the limited variations between each hour of the observation. the wind speed generates inadequate power which depends on the weather condition within the evening and morning. in this way, the python show the hourly trend variation as refer to figure. . figure. . the hourly wind speed observation all over the day. the different parameters are calculated for the period of th april . while these information views measure the help to induce a plan of the overall wind speed trend in the data. the daily trend of the wind speed is gained for the whole day. the wsmin, wsmax, wsmean and wssd show trend of the day as mentioned in figure. . figure. . the daily observation of the wind speed with the reliable deviations observable throughout the day. the weekday and the weekend trend of the wind speed are obtained to illustrate the distinction between the yield of the weekday and weekend. the wind speed for the appearance at the hourly trend on weekdays vs. weekends as presented in figure. . figure. . the wind parameter that shows hourly observation for weekday and weekend. the calculation demonstrate the hourly basis measurement. v.results&analysis the wind speed parameter like turbulence intensity, wsmin, wsmax, wsmean, and wssd have been studied to extract wind energy. the wind result reflects the conversion of the wind into the electric power in the daily, hourly, monthly and yearly trend. the python software is used to guides the result to access data in a very important piece of the pandas statistic tools. the overall wind speed parameter is observed by pandas wind energy status and potential assessment across coastal mega city, of pakistan published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s for karachi in each kind of the wind data trendline stays experimented as exposed in figure. . the weekly count is best for the wind speed observed for the period of jan to april . the python takes the software command by resampling the data as offered in figure. . the wind speed performance will highly depend on seasonal variation from summer to winter in a model. the python explores further in a very minute period of time to gives the output as publicized in figure. . the world bank obtain data by every minutes so there are many time data show zero. the result show the variances in the obtained result as shown in figure. - . the hourly trend of the model shows the limited variations between each hour of the observation. the wind speed generates adequate power which depends on the weather condition within the evening and morning. in this way, the python shows the hourly trend variation as refer to figure. . the daily trend of wind speed is gained for the whole day. the wsmin, wsmax, wsmean and wssd show trend of the day as mentioned in figure. . the weekday and the weekend trend of the wind speed are obtained to illustrate the distinction between the yield of the weekday and weekend. the wind speed for the appearance at the hourly trend on weekdays vs. weekends as presented in figure. . the obtained result terribly interesting to see wind speed modal commute pattern throughout the hourly, daily, monthly and yearly. the expanded data gives the supplementary fact, and examine the impact of the parameter that different patterns give the best trend in the hourly, daily monthly and yearly result. the observed world bank data is proving from the onshore and offshore wind resources map as shown in figure. . the karachi is the coastal city of pakistan so the wind speed of this area is commendable for the electricity generation. as the wind speed is shown in the wind resource map by the world bank group as refer figure. . figure. . the wind speed observation for the karachi by the onshore and offshore wind resources map by world bank. picture source: world bank group site. the wind power density potential for the karachi of sindh and balochistan are very effective as shown in figure. . so the data available at the world bank website for the karachi is proving the obtainable results from figure. - in the onshore and offshore wind resources map of figure. . figure. . the wind power density potential observation for the karachi by the onshore and offshore wind resources map by the world bank. picture source: world bank group site. the wind resources map is now zoomed for the observation of the wind scenario for karachi city. the wind map shows the wind speed at a different height, the data for the % windiest area is w/m the wind speed is increased as the height of the wind turbine increased as shown in figure. . international journal of recent technology and engineering (ijrte) issn: - , volume- issue- s , august published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s figure. . the wind speed observation at the different height for the karachi at the wind resources map. picture source: world bank group site. the mean power density and the windiest areas were observed in this way the karachi mean power density in the selected region is w/m . the wind speed will be increased as the height of the wind turbine is increased as shown in figure. . figure. . the observation of mean power density and the windiest areas for the karachi at the wind resources map. picture source: world bank group site. vi. discussion the world bank group put a strong effort to explore the renewable resources in the number of countries including pakistan. the world bank group get the data available for all the observed countries. so the data obtained from world bank sites located across karachi. the wind speed data was studied for the daily, hourly, monthly and yearly periods among the data sets - . the wind speed trend and the fluctuation as for as the windy day is concerned. we use the python software for the wind speed trend observation for the karachi. the pandas, a package called in python software is employed for handling a large set of python world contains a range of accessible representations of dates, times, months, andtimespans. the obtained result is being experimented by the onshore-offshore wind resources map so the world bank data for the karachi is valid for the wind potential observation across karachi. the obtained result will help us in windmills installation across karachi. the planner needs to install the windmill on the basis of the world bank data observation. in this way, the utilization of windmills, the karachi will overcome future energy demand. vii. conclusion the world bank data for renewable energy are being experimented for the wind potential observation across karachi. the obtained result will help the planner for the installation of the windmill across karachi. the planner needs to install the windmill on the basis of the world bank data observation. if windmills are exploited in the selected areas, the karachi will generate the abundant energy that overcomes the future energy demand. viii. acknowledgements thanks world bank for making the re data available for pakistan. references . s. ahmed, a. ali, d. kumar, m. z. malik, a. h. memon. china pakistan economic corridor and pakistan’s energy security: a meta-analytic review. energy policy volume , pages - (april ). . k. azad, m. rasul, p. halder, j. sutariya. assessment of wind energy prospect by weibull distribution for prospective wind sites in australia. energy procedia. volume , pages - (february ). . a. ali, d. b. rahut, m. imtiaz. effects of pakistan's energy crisis on farm households. utilities policy. volume , (august ). . ali, s.m. hassan; zuberi, m. jibran s. tariq, m. arsalan, b. derek, m. abdullah. a study to incorporate renewable energy technologies into the power portfolio of karachi, pakistan. renewable and sustainable energy reviews, volume (jul , ). . m. m. amana, g.b.jasmon, a. ghufran, a. h. a. bakar, h. mokhlis. investigating possible wind 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world bank’s renewable energy resource mapping initiative. geoforum. volume , pages - (june ). . j. urpelainen. rise to the occasion? a critique of the world bank’s regulatory indicators for sustainable energy. energy research & social science. volume , pages - (may ) authors sabir ali kalhoro sabir es @gmail.com m.engg (industrial electronics), department of electronics engineering ned university of engineering and technology karachi pakistan muhammad ali noman ali.noman@indus.edu.pk indus university karachi, pakistan maqsood ur rehman awan maqsood.rehman@duet.edu.pk department of electronic engineering, dawood university of engineering and technology, karachi, pakistan engr. tufail ahmed tufail.waseer@faculty.muet.edu assistant professor, department of electronics engineering mehran university of engineering and technology jamshoro, pakistan shafique ahmed soomro engr_shahid @yahoo.com indus university karachi, pakistan muhammad faisal m.faisal.shaikh @gmail.com indus university karachi pakistan high resolution respirometry analysis of polyethylenimine-mediated mitochondrial energy crisis and cellular stress: mitochondrial proton leak and inhibition of the electron transport system biochimica et biophysica acta ( ) – contents lists available at sciencedirect biochimica et biophysica acta journal homepage: www.elsevier.com/locate/bbabio high resolution respirometry analysis of polyethylenimine-mediated mitochondrial energy crisis and cellular stress: mitochondrial proton leak and inhibition of the electron transport system arnaldur hall a,b, anna k. larsen a,b, ladan parhamifar a,b, kathrine d. meyle a, lin-ping wu a,b, s. moein moghimi a,b,⁎ a centre for pharmaceutical nanotechnology and nanotoxicology, university of copenhagen, universitetsparken , dk- copenhagen Ø, denmark b nanoscience centre, university of copenhagen, dk- copenhagen Ø, denmark abbreviations: anti-a, antimycin a; asc, ascorbate; n bonyl cyanide m-chlorophenylhydrazone; ci, complex i; c civ, complex iv; cyt c, cytochrome c; dic, differential inte transport system; rfrs, respiratory flux ratios; fbs, fetal bo (l/e), leak control ratio; mna, malonic acid; mtg, netroutine control ratio; nadh, nicotinamide adenine d phosphorylation; pei, polyethylenimine; pi, propidium i ratio; (r/e), routine control ratio; r, routine respi residual oxygen consumption; tmpd, n,n,n′,n′-tetra tmrm, tetramethyl rhodamine methyl ester ⁎ corresponding author at: centre for pharmaceutic toxicology, university of copenhagen, universitetspark denmark. tel.: + . e-mail addresses: imedicine.moghimi@outlook.com, (s.m. moghimi). - /$ – see front matter © elsevier b.v. all http://dx.doi.org/ . /j.bbabio. . . a b s t r a c t a r t i c l e i n f o article history: received april received in revised form june accepted july available online july keywords: cell death cytochrome c oxidase electron transport system mitochondrial membrane potential mitochondrial uncoupling polyethylenimine polyethylenimines (peis) are highly efficient non-viral transfectants, but can induce cell death through poorly understood necrotic and apoptotic processes as well as autophagy. through high resolution respirometry studies in h cells we demonstrate that the kda branched polyethylenimine ( k-pei-b), in a concentration and time-dependent manner, facilitates mitochondrial proton leak and inhibits the electron transport system. these events were associated with gradual reduction of the mitochondrial membrane potential and mitochondrial atp synthesis. the intracellular atp levels further declined as a consequence of pei-mediated plasma membrane damage and subsequent atp leakage to the extracellular medium. studies with freshly isolated mouse liver mitochondria corroborated with bioenergetic findings and demonstrated parallel polycation concentration- and time-dependent changes in state and state o oxygen flux as well as lowered adp phosphorylation (state ) and mitochondrial atp synthesis. polycation-mediated reduction of electron transport system activity was further demonstrated in ‘broken mitochondria’ (freeze-thawed mitochondrial preparations). moreover, by using both high-resolution respirometry and spectrophotometry analysis of cytochrome c oxidase activity we were able to identify complex iv (cytochrome c oxidase) as a likely specific site of pei mediated inhibition within the electron transport system. unraveling the mechanisms of pei-mediated mitochondrial energy crisis is central for combinatorial design of safer polymeric non-viral gene delivery systems. © elsevier b.v. all rights reserved. . introduction synthetic polycations have gained increasing attention as non-viral delivery systems for nucleic acid therapeutics [ – ]. polycations such as polyethylenimines (peis) and their derivatives are effective transfec- tion reagents by their capacity to compact nucleic acids into polyplexes, thereby protecting the nucleic acids from degradation, as well as an , sodium azide; cccp, car- ii, complex ii; ciii, complex iii; rference contrast; ets, electron vine serum; l, leak respiration; mitotracker green; ((r-l)/e), inucleotide; oxphos, oxidative odide; rcr, respiratory control ration; rote, rotenone; rox, methyl-p-phenylenediamine; al nanotechnology and nano- en , dk- copenhagen Ø, moien.moghimi@sund.ku.dk rights reserved. promoting their successful delivery into a wide range of cells [ , – ]. the majority of polyplexes enter cells via clathrin-mediated endocyto- sis, but there are many other suggested internalization mechanisms, in- cluding caveolae-mediated pathways as well as internalization through polycation-mediated plasma membrane perturbation/destabilization processes [ , – ]. despite the fact that synthetic polycations are effec- tive non-viral candidates, it is of great concern that the polycations showing the best transfection efficiency, typically also display higher cytotoxicity [ , , – ]. peis are the best investigated polycationic vectors existing in both linear and branched morphology [ , ]. the kda branched pei ( k-pei-b) is among the most efficient polycationic transfection agents, but also induces severe cytotoxicity in clinically relevant human cell lines [ ]. accordingly, there have been numerous empir- ical and combinatorial approaches to lessen pei-induced cytotoxicity. some of these modifications have reduced cytotoxicity, but at the ex- pense of poor transfection efficacy and low duration period-specific gene expression or silencing; however, in most cases cytotoxicity still persists when examined closely [ , ]. the underlying mecha- nisms of pei-induced cytotoxicity are complex, multifaceted and not fully understood. a number of studies have shown that pei can induce http://dx.doi.org/ . /j.bbabio. . . mailto:imedicine.moghimi@outlook.com mailto:moien.moghimi@sund.ku.dk http://dx.doi.org/ . /j.bbabio. . . http://www.sciencedirect.com/science/journal/ http://crossmark.crossref.org/dialog/?doi= . /j.bbabio. . . &domain=pdf a. hall et al. / biochimica et biophysica acta ( ) – cell death through multiple pathways (e.g., necrosis, apoptosis and autophagy) with mitochondrial involvement [ , , – ]. indeed, mitochondria play a vital role in cellular energy metabolism and the mitochondrial membrane potential (Δψm) is a key indicator of cell viability; loss of Δψm is associated with cellular stress and cell death, and dissipation of Δψm may promote apoptosis [ ]. the Δψm is generated from the build-up of proton-driven electrochemi- cal gradient across the inner mitochondrial membrane, as a result of the activity of the protein complexes of the electron transport system (ets) and the integrity of the mitochondrial inner membrane [ , ]. electrons that originate from the oxidation of reduced nicotinamide adenine dinucleotide (nadh) by complex i (nadh-ubiquinone oxidoreductase; ci), and from oxidation of succinate by complex ii (succinate-ubiquinone oxidoreductase; cii), flow through the electron transport system with molecular oxygen being the final electron accep- tor [ ]. electron transport through the ets is coupled with proton trans- location by the inner membrane complexes i, iii (ubiquinol-cytochrome c oxidoreductase; ciii) and iv (cytochrome c oxidase; civ). this activity generates the electrochemical proton gradient, which is utilized by the mitochondrial f /f -atp synthase to produce atp [ , ]. the proton pumps of the electron transport system, together with the atp synthase, create a proton circuit across the inner membrane, which is central to mitochondrial bioenergetics and cellular homeostasis [ – ]. this inte- grated process of mitochondrial respiration is referred to as oxidative phosphorylation (oxphos) and the inability of mitochondria to suffi- ciently produce atp can lead to energy depletion and cellular stress, and may induce cell death through different pathways [ – ]. earlier studies have shown that exposure of various human cell lines to pei and pei/dna complexes initiates loss of Δψm [ ] as well as cyto- chrome c (cyt c) release from the mitochondrial intermembrane space [ , ]. furthermore, studies with isolated mitochondria have demon- strated pei-mediated inhibition of respiration, dissipation of Δψm and large amplitude osmotic swelling [ ]. these observations strongly in- dicate that cytoplasmic pei may perturb mitochondrial membranes and interfere with electron transport processes. accordingly, we have now examined the effect of k-pei-b on bioenergetic processes with a specific focus on mitochondrial proton leak and ets capacity in h cell line as well as in freshly isolated mouse liver mitochondria and ‘broken mitochondria’ (freeze-thawed mitochondrial preparations). a better understanding of these events could open the path for design- ing safer polymers through combinatorial approaches for transfection purposes and achieving clinically acceptable duration period-specific gene expression or silencing. . materials and methods . . materials the k-pei-b (dissolved in milli-q h o) and cyt c oxidase assay kit were purchased from sigma-aldrich (denmark). the atplite lumines- cence assay system was purchased from perkin elmer (skovlunde, denmark). hoechst- , mitotracker green (mtg), propidium iodide (pi) and tetramethyl rhodamine methyl ester (tmrm) were purchased from life technologies europe bv (denmark). all other materials were purchased from sigma-aldrich (denmark). . . cell culture h cells (atcc number: crl- ; sigma-aldrich) were cultured in rpmi- medium at °c with . mg/ml penicillin/ streptomycin, mm l-glutamine and % fbs in % o and % co . cells were harvested at – % confluence and not allowed to exceed passages. experiments pertaining to h cells were performed at – % confluence. . . live cell imaging and measurements of mitochondrial membrane potential in h cells h cells were seeded ( . × cells/well) in μl in μ-slide well-plates (ibidi, denmark). cells were grown to – % confluency and thereafter stained with the mitochondrial dyes mtg ( nm) and tmrm ( nm) as well as with the nuclear dye hoechst- ( μg/ml) for min at °c. mtg accumulates into polarized mito- chondria and binds covalently to intramitochondrial protein thiols where it remains bound after depolarization, whereas tmrm accumu- lates in a Δψm-dependent manner and leaks out of mitochondria after reduction in Δψm [ – ]. after staining, cells were washed twice and subjected to μg/ml k-pei-b in growth medium at °c followed by live cell imaging. imaging was performed on a leica af lx mi- croscope equipped with a × (numerical aperture = . ) oil objec- tive using . × magnification. images were acquired with appropriate red (excitation with band pass = / nm, emission with band pass = / nm), green (excitation with band pass = / nm, emission with band pass = / nm) and blue (excitation with band pass = / nm, emission with band pass = / nm) fil- ters, respectively. in addition, differential interference contrast (dic) images were taken simultaneously to visualize morphological changes. z-stacking was performed using appropriate sectioning steps. alter- ations of tmrm and mtg fluorescence intensity were quantified with facs (bd facs array™ cell analysis) ( , events were counted) at different time intervals of pei exposure. cell viability was followed by facs and microscopy. briefly, cells were stained with the nucle- ar dye hoechst- ( μg/ml, min, °c) and washed twice and stained with μg/ml pi for min at °c. cells were then incubated with μg/ml k-pei-b for min at °c before analysis. . . isolation of mouse liver mitochondria mouse liver mitochondria were isolated from young female nmri mice (approximately – weeks old and – g in body weight). all animals used in this study were housed in a light/dark phase cycle of h with free access to food and water. the animals were killed by cervical dislocation and the liver was rapidly removed, rinsed and minced with scissors, in ice-cold isolation medium (mannitol mm, sucrose mm, tris–hcl mm, egta . mm and bsa mg/ml, ph . ). the liver was subsequently homogenized in a potter–elvehjem glass homogenizer using a motor-driven teflon-pestle. the liver homogenate was centrifuged for min at ×g, the superna- tant was decanted and the centrifugation step was repeated again. the supernatant was then centrifuged for min at ×g and the resulting pellet was suspended in isolation medium without bsa and centrifuged for min at , ×g. the final mitochondrial pellet was suspended in isolation medium without bsa, to a final protein concentra- tion of approximately mg/ml. all procedures were carried out on ice and the centrifugation steps were performed at °c. experiments were performed using mitochondrial preparations with high respi- ratory control ratios (rcrs of – ) indicating that the isolated mito- chondria are of high functional quality with a high capacity for oxidation of respiratory substrates, effective atp synthesis and a low degree of proton leak [ , ]. . . high-resolution respirometry respiration in intact cells, freshly isolated mitochondria and freeze- thawed mitochondrial preparations was monitored with high-resolution respirometry (oroboros oxygraph- k, innsbruck, austria) using a chamber volume set to ml [ ]. calibration with air-saturated medium was performed daily. data acquisition and analysis were carried out using datlab software (oroboros instruments). a. hall et al. / biochimica et biophysica acta ( ) – . . . intact h cells h cells were suspended (in growth medium) in the ml glass chamber at a density of . × cells/ml at °c and there- after investigated using a phosphorylation control protocol [ ] (supplementary fig. s ). cellular respiration was first allowed to stabilize at steady-state without any additions to the cell medium. at steady-state respiration (o consumption), the respiratory flux is constant. this defines the routine respiration state (i.e. the physiological coupling state controlled by cellular energy demands). after observing routine state for min, pei or h o (control) was added to the chamber. after incubation with pei (at , or min), the atp synthase was inhibited by addition of oligomycin ( μg/ml) in order to detect the level of leak respiration. the leak state of respiration is independent of adp phosphorylation, and mainly oc- curs due to proton leak from the mitochondrial intermembrane space [ – ]. the maximal capacity of the ets was obtained by stepwise titrations ( . μm) with the protonophore, carbonyl cya- nide m-chlorophenylhydrazone (cccp) until maximal respiratory flux could be detected [ ]. following this, respiration was sequen- tially inhibited by addition of rotenone (rote) at . μm, to selectively inhibit ci, and then antimycin a (anti-a) at . μm, to inhibit the fig. . the relationship between mitochondrial membrane potential (Δψm) and cell death follow hoechst- in growth medium for min at °c. after staining, cells were washed twice a imaging at different time intervals, panel (a). mtg accumulates in the mitochondria independ tmrm and mtg were both initially taken up only by polarized mitochondria, the gradual los mtg indicate loss of Δψm on pei challenge. this is also confirmed in the loss of yellow in the ov rescence intensity by facs, whereas the scatterplots in panel (c) represent changes in cellu pei-mediated cell death events monitored by propidium iodide (pi) staining. pi nuclear stainin activity of ciii. the resulting state provides a measure of residual oxygen consumption (rox). mitochondrial respiration was corrected for oxy- gen flux due to instrumental background and rox [ – ]. the rate of mitochondrial atp synthesis (oligomycin-sensitive respiration) was calculated as the difference between routine respiration and leak respiration. . . . freshly isolated mouse liver mitochondria respiration in isolated mitochondria was investigated at °c in a mitochondrial respiration medium (mir ) containing egta . mm, mgcl mm, k-lactobionate mm, taurine mm, kh po mm, hepes mm, sucrose mm and bsa free from fatty acids g/l, ph . [ ]. respiring mitochondria were supplemented with respi- ratory substrates (glutamate mm, malate mm and succinate mm) for combined electron flow through ci and cii [ ]. in all experiments, the following protocol was applied (supplementary fig. s ), using a mitochondrial protein content of . – . mg/ml. briefly, leak mitochondrial respiration (state ) was first allowed to stabilize in the presence of respiratory substrates without the addition of adp to the respiration medium. next, k-pei-b or h o (control) was added to the mitochondrial suspension and incubated ing pei challenge in h cells. cells were loaded with mtg, tmrm and the nuclear dye nd challenged with k-pei-b ( μg/ml) in growth medium at °c followed by live cell ent of the Δψm, whereas tmrm accumulates in a Δψm-dependent manner. since cationic s of tmrm red fluorescence and recovery of the green fluorescence of covalently bound erlay images. scale bar = μm. panel (b) shows quantification of tmrm and mtg fluo- lar size (fs) and granularity (ss) following pei exposure. panel (d) is representative of g becomes prominent from min and onward. scale bar = μm. fig. (continued). a. hall et al. / biochimica et biophysica acta ( ) – for or min, followed by addition of adp at saturating concentra- tion ( . mm). this results in maximal, adp-stimulated respiration (state ) and atp synthesis by the mitochondrial f /f -atp synthase [ , ]. subsequent addition of oligomycin ( μg/ml) was added to achieve non-phosphorylating leak respiration (state o), mainly driven by proton leak from the mitochondrial intermembrane space after oligomycin-mediated inhibition of the atp synthase [ , ]. finally, respiration was selectively inhibited first by addition of rotenone at . μm and next anti-a at . μm, to inhibit ci and ciii, respectively, providing measure of rox. mitochondrial respiration was corrected for oxygen flux due to instrumental background and rox [ , ]. mitochondrial atp synthesis was calculated as the difference be- tween state and state o. . . . ‘broken mitochondrial’ preparation the interference of k-pei-b with components of the ets was investigated in a ‘broken mitochondrial’ preparation ( . – . mg/ml final protein concentration) at °c in mir . ‘broken mitochondria’ were obtained by three freezing–thawing cycle disruption of isolated mouse liver mitochondria suspended in isolation medium (mannitol mm, sucrose mm, tris–hcl mm, egta . mm, at ph . ). a combination of succinate ( mm) and nadh ( mm) was used to divert electrons simultaneously through ci and cii, together with exter- nal addition of cyt c ( μm) to obtain steady flow of electrons from ciii to civ [ , ]. additions of k-pei-b ( μg/ml per step) were applied to investigate the potential interference of pei with the protein com- plexes of the electron transport system. at the end of each experiment, . mm potassium cyanide (kcn) was added to obtain a measure of rox. oxygen consumption by the ets was corrected for oxygen flux due to instrumental background and rox [ , ]. in addition, the effect of pei on electron flow through ci–ciii–civ was investigated in ‘broken mitochondria’ in the presence of nadh ( mm) to divert electrons through ci, together with external addition of cyt c ( μm) in order to obtain a steady flow of electrons from ciii to civ [ , ]. further- more, the effect of pei on electron flow through cii–ciii–civ was inves- tigated in the presence of succinate ( mm) to divert electrons through cii, together with rotenone ( . μm) to inhibit ci and external addition of cyt c ( μm) to obtain steady flow of electrons from ciii to civ [ , ]. finally, the activity of civ was investigated in the presence of . mm n,n,n′,n′-tetramethyl-p-phenylenediamine (tmpd), mm ascorbate (asc), μm cyt c, . μm rotenone, mm malonic acid (mna) and . μm anti-a following sequential additions of different image of fig.� fig. (continued). a. hall et al. / biochimica et biophysica acta ( ) – concentrations of k-pei-b. finally, mm sodium azide (nan ) was added to inhibit civ activity, providing measure of rox. oxygen consumption by the ets was corrected for oxygen flux due to instru- mental background and rox [ , ]. . . spectrophotometric analysis of civ activity the activity of civ was investigated in a ‘broken mitochondrial’ preparation ( . μg final protein concentration per sample) in the presence of different concentrations of k-pei-b using cyt c oxidase assay kit (sigma-aldrich). briefly, the civ activity was monitored at λ = nm in a tecan microplate reader (infinite m , tecan nordic ab, sweden) and following absorbance measurements, cal- culations of civ activity (nmol/min/mg) were performed according to manufacturer's instructions. . . atp determination the concentration of atp was determined using a modified method based on the atplite luminescence assay system (perkin-elmer). briefly, h cell suspensions ( . × cells/ml) were incubated with k-pei-b for appropriate times at °c in growth medium. in parallel, experiments were done using high-resolution respirometry. following incubation, the cell pellet was separated from the medium by centrifugation at ×g for min at °c in order to obtain sepa- rate measurements of intra- and extracellular atp. after separation the samples were left on ice to slow down degradation of the atp molecules and the samples were quickly mixed with lysis solution ( : medium:cell lysis buffer) (atplite, perkin elmer). atp concen- trations were measured based on triplicate aliquots taken from the sample in : ratio with substrate solution (atplite, perkin elmer). luminescence was recorded in a tecan microplate reader (infinite m , tecan nordic ab, sweden). . . trypan blue exclusion test trypan blue staining was used to investigate the effects of pei exposure on plasma membrane damage. briefly, suspensions of . × cells/ml were incubated with k-pei-b at °c in growth medium for appropriate times. following pei exposure, cells were stained with trypan blue and counted under the microscope. data is presented as % of cells excluding trypan blue. . . statistical analysis results are expressed as means ± sd from at least three inde- pendent experiments except stated otherwise. statistical analyses and comparison of different groups in relation to one or two factors were performed with one-way anova or two-way anova as appro- priate. the bonferroni method was subsequently used to correct p values after multiple comparisons to calculate statistical significance. image of fig.� fig. (continued). a. hall et al. / biochimica et biophysica acta ( ) – values of p b . post bonferroni corrections were taken as the level of significance. . results . . loss of Δψm precedes cell death in h cells on pei exposure the loss of Δψm plays a key role in mitochondrial-mediated cell death [ ]. accordingly, we followed the effect of pei on Δψm in h cells co-loaded with mtg and tmrm. pei ( μg/ml) induced gradual time-dependent loss of Δψm starting within min of expo- sure (fig. a, b). however, the fs/ss scatterplots, where fs reflects cell size and ss cell granularity, indicated that by min of pei exposure the majority of cells (represented in a contour of equal probability density in the distribution of untreated cells) are in viable state (fig. c). obser- vations with h cells stained with pi and hoechst- (fig. d) further corroborate with these findings. cell death, however, be- comes prominent at longer exposure time ( min). collectively, these results show that h cells are highly sensitive to pei expo- sure and may serve as a convenient model to investigate the likely mechanism(s) by which pei could induce mitochondrial failure at early time points (under min), where the majority of cells are still in viable state. . . pei-mediated changes on mitochondrial respiratory states in intact cells the results in fig. show how pei at different concentrations severely affects various respiratory states in h cells, based on a standardized phosphorylation control titration protocol (supplementary figs. s , s and s ). pei affected routine respiration in a concentration and time-dependent manner (fig. a). within min of addition, pei sig- nificantly increased o flux at concentrations above μg/ml. this initial pei concentration-dependent respiratory increase, however, was followed by a gradual decline over time. the effect was more prom- inent with a pei concentration of μg/ml (starting at min), but with lower concentrations ( μg/ml) the respiratory decline (o flux) became significantly different at later time points ( min). in parallel with routine respiration, pei also increased leak res- piration in a concentration-dependent manner at min of exposure (fig. b). by min, the pei-mediated increase in leak respiration declined and the values were comparable with the control incubation. only at min the decline was significantly lower with a pei concen- tration of μg/ml (fig. b). the decline phase became more prom- inent with higher pei concentrations and observable within min of exposure (data not shown). pei was also found to significantly in- hibit the maximal capacity of the ets, again in a concentration- and time-dependent manner (fig. c). here, pei at μg/ml was capable image of fig.� fig. . the effect of pei concentration on respiratory states and atp synthesis in h cells. respiration (indicated as the rate of oxygen consumption or o flux) was evaluated at different stages (routine, leak, ets and atp synthesis) on pei challenge ( – μg/ml). statistical analyses were performed with two-way anova, using bonferroni multiple comparison correction to calculate significance (*p b . , **p b . ). a. hall et al. / biochimica et biophysica acta ( ) – of significantly reducing ets after min of incubation. furthermore, the results in fig. d show that pei affects mitochondrial atp synthesis (oligomycin-sensitive respiration). the reduced capacity of intact mito- chondria to synthesize atp is significantly observed with pei levels of μg/ml at longer periods of time ( min) as well as with higher concentrations but at shorter periods of incubation ( min). next, we calculated the effect of pei concentration and exposure time on corresponding respiratory flux ratios (rfrs) (table ). the rfrs are defined as o flux in different respiratory control states, normalized for maximum flux of the ets capacity, acquiring theoret- ically lower and upper limits of . and . [ , ]. pei increased rfr values in a time- and concentration-dependent manner. however, at μg/ml pei-augmented rfr values declined on longer exposure time when compared with controlled cells. the routine control ratio (r/e) is the ratio of routine (r) respiration and ets (e) capacity; this gives an estimate of how close routine respiration operates to the ets capacity. an increasing r/e is indicative of increasing cellular atp demand, mitochondrial uncoupling and/or the limitation of respiratory table flux ratios in intact cells following incubation with k-pei-b. k-pei-b rcr “r/e” lcr “l/e” time [min] control . ± . , ± . . ± . . ± . . μg/ml . ± . . ± . * . ± . ** . ± . . μg/ml . ± . . ± . ** . ± . ** . ± . ** . μg/ml . ± . ** . ± . ** . ± . ** . ± . ** . flux ratios are calculated as the means ± sd for parallel experiments. statistical analyses we calculate significance (*p b . ; **p b . ). the routine control ratio (r/e) is the ratio of rou respiration operates to the ets capacity. the leak control ratio (l/e) is the ratio of leak (l) resp the ets capacity remains constant. the netroutine control ratio ((r-l)/e) represents phospho μg/ml pei the increase in leak respiration (fig. b) is fully compensated by increasing rout capacity by impaired activity of ets components [ ]. the leak control ratio (l/e) is the ratio of leak (l) respiration and ets capacity. when the ets capacity remains constant, l/e provides an estimation of mito- chondrial uncoupling. pathological uncoupling can be caused by toxic external agents and is thus distinct from intrinsic uncoupling [ ]. the data summarized in table indicates that the early concentration- dependent increases in l/e ratios are a result of pei mediated uncoupling of the mitochondria as leak respiration is significantly increased following min incubation with μg/ml pei (fig. b), whereas the ets capacity remains constant (fig. c). the netroutine control ratio ((r-l)/e) represents the phosphorylation related respi- ration as a fraction of ets capacity. this provides an estimation of cell functioning with respect to its bioenergetic limit [ ]. the early ( min) increase in leak respiration at lower pei concentrations ( and μg/ml) (fig. b) is fully compensated by increased routine respiration (fig. a). consequently, the (r-l)/e is unaffected and mi- tochondrial atp synthesis is maintained at a constant rate (fig. d). at later time points ( and min), the changes in (r-l)/e result netrcr “(r-l)/e” ± . . ± . . ± . . ± . . ± . ± . . ± . ** . ± . . ± . . ± . ** ± . ** . ± . ** . ± . . ± . ** . ± . ** ± . ** . ± . ** . ± . ** . ± . ** . ± . ** re performed with two-way anova, using bonferroni multiple comparison correction to tine (r) respiration and ets (e) capacity. the r/e gives an estimate of how close routine iration and ets capacity. the l/e provides an estimation of mitochondrial uncoupling when rylation related respiration as a fraction of ets capacity. after min exposure with and ine respiration (fig. a) and therefore no changes are observed in the (r-l)/e. image of fig.� fig. . the effect of pei concentration on mitochondrial proton leak in isolated mouse liver mitochondria. panels (a) and (b) show the effect of pei concentration on state and o respirations, respectively at two different time points. bars represent the mean ± sd of parallel experiments. statistical analyses (with respect to control and between indicated pairs) were performed with repeated measurement one-way anova, using bonferroni multiple comparison correction to calculate significance (*p b . , **p b . ). a. hall et al. / biochimica et biophysica acta ( ) – from gradual decline of the ets capacity following pei exposure (fig. c) thus driving cells to utilize more of their respiratory capac- ity to maintain constant atp synthesis. . . pei-mediated changes on respiratory states in freshly isolated mouse liver mitochondria the results in fig. show the effect of different pei concentration on the respiratory functions of well-coupled, freshly isolated mouse liver mitochondria at two different time points. pei exposure for min significantly increased both state and state o o fluxes (fig. a & b). increased o flux during state o respiration is indicative of accelerated proton leak or proton transfer across the inner mito- chondrial membrane [ , , ]. the increased proton leak, however, declined after longer incubation periods ( min) with higher pei levels ( and μg/ml). furthermore, pei significantly lowered the ability of the mitochondria to phosphorylate adp (state ) in a time- and concentration-dependent manner (fig. a). notably, the lowest pei-concentration tested ( μg/ml) increased proton leak sig- nificantly after min (fig. a & b), although state respiration was not declined until after min incubation (fig. a). correlating with the observed pei-mediated effect on state and state o respiration, mitochondrial atp synthesis (oligomycin-sensitive respiration) also significantly decreased at all tested pei concentrations (fig. b; repre- sentative oxygraph traces are shown in supplementary figs. s –s ). the results in table summarize the calculated mitochondrial respi- ratory control ratios (rcrs) as indicators of pei-induced mitochondrial dysfunction. high rcr values imply high mitochondrial capacity for oxidation of respiratory substrates, atp synthesis and a low degree of proton leak [ ]. the results clearly show that rcr values decrease sig- nificantly in response to the increasing concentrations of the polycation (table ). . . pei acts as a potent inhibitor of ets activity in ‘broken mitochondria’ we next examined the consequence of exposing ets components directly to pei. therefore, the activity of the ets (o flux) was moni- tored using a ‘broken mitochondrial’ preparation following the addi- tion of pei in the presence of combined electron flow into the ets through ci and cii [ ]. these results strongly suggest that pei is a potent inhibitor of the ets even at μg/ml (supplementary fig. s ). to pinpoint the specific site of pei mediated inhibition within the ets, we used a substrate combination to feed electrons specifically to either ci or cii. the results in fig. a–d show that pei both impairs electron transport through ci– ciii–civ and cii–ciii–civ, suggesting that pei is acting as an inhibitor of electron flow downstream of both ci and cii. notably, the civ cata- lyzes transfer of electrons from cyt c to oxygen through electrostatic interactions [ ] and due to its polycationic nature pei could perhaps in- terfere with these processes. by using both high-resolution respirometry and spectrophotometric-based cyt c oxidase activity measurements, we found that even at very low concentrations ( . – . μg/ml) pei acts as a potent inhibitor of civ activity (figs. e–f & ). image of fig.� fig. . the concentration-dependent effect of pei on mitochondrial state respiration and atp synthesis (oligomycin-sensitive respiration) in isolated mouse liver mitochondria. bars represent the mean ± sd of parallel experiments. statistical analyses (with respect to control and between indicated pairs) were performed with repeated measurement one-way anova, using bonferroni multiple comparison correction to calculate significance (*p b . , **p b . ). a. hall et al. / biochimica et biophysica acta ( ) – . . the effect of pei on intracellular atp levels and plasma membrane integrity addition of pei to h cells dramatically reduced the levels of intracellular atp in a concentration-dependent manner (fig. a). this is fully in line with the abovementioned observations on pei- mediated proton leak, impaired ets capacity and decreased atp syn- thesis. however, the extent of atp loss remains similar at different time points for each particular pei concentration. in parallel, the extracellular atp levels increased on increasing pei concentration (fig. b), but the accumulated atp levels did not fully account for the total loss of intracellular atp. this presumably indicates reduced mitochondrial atp synthesis (or increased cellular atp consumption), which is in line with the results in figs. & . the data in fig. c further show that pei dramatically reduces plasma membrane integrity even at low concentrations ( μg/ml); this may account for the appearance of extracellular atp. table mitochondrial respiratory control ratio (rcr) (state /state o). k-pei-b control μg/ml μg/ml μg/ml [ min] . ± . . ± . ** . ± . ** . ± . ** [ min] . ± . . ± . ** . ± . ** . ± . ** rcr is calculated as mean ± sd for parallel experiments. statistical analyses were performed with two-way anova and bonferroni multiple comparison correction to calculate significance (**p b . ). . discussion to the best of our knowledge, this is the first study demonstrating concentration- and time-dependent effect of pei on mitochondrial proton leak and its inhibitory effect on the ets in intact cells. indeed, we have now demonstrated that extracellular pei at a concentration range of – μg/ml can rapidly (within min) induce mild mito- chondrial uncoupling in h cells. this is shown by the fact that the increase in l/e ratio (table ) occurs only due to increased proton leak as a result of increased leak respiration, whereas the ets capac- ity remains unchanged (indicative of pei-mediated proton leak). interestingly, subsequent to pei-induced increase in mitochondrial proton leak, pei also caused a concentration-dependent decline in proton leak at later time points. this suggests that pei exerts additional effects on mitochondrial functions. moreover, pei further induced sig- nificant concentration- and time-dependent inhibitory effect on the ets capacity in intact cells, which presumably is due to impairment of substrate oxidation [ ]. it should be emphasized that although mito- chondrial permeabilization could lead to reduced oxphos capacity, mi- tochondrial permeabilization alone is not capable of inhibiting electron transfer and substrate oxidation by the ets components [ , , – ]. however, reduction of state respiration in isolated mitochondria could be induced by impaired substrate oxidation [ ]. therefore, we speculate that pei has an inhibitory role on the ets components. earlier attempts with other types of polycations (e.g., polylysines) demon- strated their inhibitory effect on civ activity [ ]. in line with these suggestions, experiments with ‘broken mitochondrial’ preparations image of fig.� fig. . the inhibitory effect of pei on the electron transport system activity in ‘broken mitochondria’. oxygen consumption (o flux) was measured in a substrate combination of nadh and cyt c or combination of succinate, rotenone (rote) and cyt c for specific electron flux through ci–ciii–civ or cii–ciii–civ, respectively. moreover, the activity of civ was measured with combination of tmpd, ascorbate (asc), cyt c, rotenone, antimycin-a and malonic acid. panels (a) and (c) represent high resolution respirometry and representative trace of oxygen flux through ci–ciii–civ and cii–ciii–civ in ‘broken mitochondria’, respectively. oxygen consumption was measured on five cumulative additions of k-pei-b ( μg/ml per addition). panels (b) and (d) show reduction of ci–ciii–civ and cii–ciii–civ activity in ‘broken mitochondria’ exposed to cumulative concentrations of pei relative to control, respectively. bars represent the mean ± sd of parallel experiments. panel (e) shows high-resolution respirometry and representative trace of oxygen flux through civ in ‘broken mitochondria’. oxygen consump- tion was measured on five cumulative additions of k-pei-b (first addition: . μg/ml, second addition: . μg/ml, third addition: . μg/ml, fourth and fifth additions: μg/ml each). panel (f) shows relative reduction of civ activity in ‘broken mitochondria’ following exposure to different concentrations of pei. bars represent the mean ± sd of parallel experiments. statistical analyses were performed with one-way anova, using bonferroni multiple comparison correction to calculate significance (*p b . , **p b . ). a. hall et al. / biochimica et biophysica acta ( ) – confirmed that pei inhibits electron flow and substrate oxidation by the ets due to its potent inhibitory effect at least on civ activity even at very low concentrations. the observation that pei inhibits ets activity correlates well with the fact that the early increase of mito- chondrial proton leak following pei exposure declines again at later time points. consequently, ets translocates fewer protons over the inner membrane and therefore fewer protons are available in the intermembrane space to leak back through the inner membrane into the matrix, explaining partially why the early acceleration of mitochondrial proton leak following pei exposure declines with longer incubation times. collectively, the experimental evidence shows that in addition to induce mitochondrial proton leak, pei acts as a potent inhibitor of the ets by inhibiting the activity of civ. pei-mediated mitochondrial destabilization is conceivably a con- sequence of the membrane perturbation properties of the polycation and formation of nanoscale pores in a similar manner to the function of pore-forming peptides [ ]. these processes are presumably similar to the function of pore-forming peptides such as alamethicin, which also possesses high affinity toward mitochondrial membranes as their membrane insertion and pore forming ability are largely driven by the image of fig.� fig. . determination of the inhibitory effect of pei on civ activity in ‘broken mitochondria’ by spectrophotometric analysis of cytochrome c oxidase activity. bars represent the mean ± sd of parallel experiments. statistical analyses were performed with one-way anova, using bonferroni multiple comparison correction to calculate significance (*p b . , **p b . ). a. hall et al. / biochimica et biophysica acta ( ) – Δψm [ ]. these pore-forming peptides induce nonspecific permeability changes, which can result in swelling and disruption of the mitochon- dria [ ]. similarly, k-pei-b was recently shown to induce swelling of isolated rat liver mitochondria at low concentrations [ ]. on the basis of these speculations, the cytoplasmic concentration of functional pei must be sufficiently enough to induce the observed mitochondrial perturbations. pei enters cytoplasm most likely through plasma mem- brane, as a result of electrostatic interactions and its detergent activity fig. . the time- and concentration-dependent effect of pei on intracellular atp depletion challenge with increasing concentrations of k-pei-b at different time points. cells treated w comparison of intra- and extracellular atp levels at hour incubation with k-pei-b. in (a) an were performed with one-way anova, using bonferroni multiple comparison correction cells (based on trypan blue exclusion test) after challenge with pei at indicated concentra [ ], and endosome destabilization (most likely arising from pei- mediated membrane fragment micellization) [ , ]. recent studies also attest that fluorescently labeled extracellular pei reaches mito- chondria in intact cells [ ]. mitochondrial atp synthesis is dependent on the electrochemical proton gradient [ , ]. correspondingly, we observed significant reduction in mitochondrial atp synthesis and drop in intracellular atp levels after pei exposure, which may partly arise due to increased atp consumption. we also found that the intracellular atp depletion was partly a consequence of pei induced damage to the plasma mem- brane and atp leakage. previous studies have shown that pei can in- duce cell death through both apoptotic and necrotic pathways [ , ]. it has also been suggested that mild reductions in intracellular atp levels could trigger apoptosis, whereas profound atp depletion may initiate necrosis [ , , ]. it is therefore conceivable that pei-induced necrotic and/or apoptotic cell death processes are driven by the magni- tude of bioenergetic crisis (mitochondrial uncoupling, impaired ets activity and diminished atp synthesis) and the extent of plasma membrane destabilization, which in turn depends on the initial pei concentration. accordingly, pei could induce apoptosis in a stochas- tic manner, with different cells entering apoptosis at different times depending on the extent of plasma membrane damage, intracellular pei levels and its effect on mitochondrial atp synthesis. with pro- found plasma membrane damage atp leakage is accelerated, which together with diminished atp synthesis may trigger cell death predominantly through necrosis. the k-pei-b also accumulates in lysosomes without inducing change in lysosomal ph [ ]. and plasma membrane integrity. panel (a) shows intracellular atp levels following ith potassium cyanide (kcn, . mm) were used as a positive control. panel (b) shows d (b) the bars represent the mean ± sd of three parallel experiments. statistical analyses to calculate significance (*p b . , **p b . ). panel (c) shows percentage of viable tions. image of fig.� image of fig.� a. hall et al. / biochimica et biophysica acta ( ) – additionally, subsequent pei-mediated lysosomal membrane perturba- tions may also contribute to cellular stress through possible release of lysosomal cathepsins, which are endowed with the capacity to cleave bid [ ]. likewise, a role for pei-mediated perturbation of endoplasmic reticulum cannot be disregarded, which could also lead to energy crisis and cellular stress through activation of procaspase [ ]. these possi- bilities are currently under investigation. in summary, this study has offered new insights as how branched peis could initiate mitochondrial failure and induce bioenergetic crisis through direct effect of pei on mitochondria. further structure–activity studies are still necessary to unravel the effect of pei architecture and size on mitochondrial processes and energetic functions both directly and through pei-mediated perturbation of other organelles. indeed, a better molecular understanding of pei-mediated mitochondrial failure events and cellular bioenergetic crisis could open the path for rational combinatorial design and construction of efficient and safer polycations (and other polymers) for nucleic acid delivery. competing interests the authors declare no competing financial interests. acknowledgements financial support by the danish agency for science, technology and innovation (det frie forskningsråd for teknologi og produktion, reference - - and det strategiske forskningsråd, reference - /dsf) is gratefully acknowledged. appendix a. supplementary data supplementary data to this article can be found online at http:// dx.doi.org/ . /j.bbabio. . . . references [ ] h.m. aliabadi, p. mahdipoot, h. uludag, polymeric delivery of sirna for dual silenc- ing of mcl- and p-glycoprotein and apoptosis induction in drug-resistant breast cancer cells, cancer gene ther. 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( ) – . [ ] a. berson, s. renault, p. letteron, m.a. robin, b. fromenty, d. fau, m.a. lebot, c. riche, a.m. durandschneider, g. feldmann, d. pessayre, uncoupling of rat and human mitochondria: a possible explanation for tacrine-induced liver dysfunc- tion, gastroenterology ( ) – . [ ] b.s. mochan, w.b. elliott, p. nicholls, patterns of cytochrome-oxidase inhibition by polycations, j. bioenerg. ( ) – . [ ] d.s. cafiso, alamethicin — a peptide model for voltage gating and protein mem- brane interactions, annu. rev. biophys. biomol. ( ) – . [ ] s. eisenhofer, f. tookos, b.a. hense, s. schulz, f. filbir, h. zischka, a mathematical model of mitochondrial swelling, bmc res. note ( ) . [ ] r.v. benjaminsen, m.a. mattebjerg, j.r. henriksen, s.m. moghimi, t.l. andresen, the possible ‘proton sponge’ effect of polyethylenimine (pei) does not include change in lysosomal ph, mol. ther. ( ) – . [ ] v.l. gabai, a.b. meriin, j.a. yaglom, j.y. wei, d.d. mosser, m.y. sherman, suppression of stress kinase jnk is involved in hsp -mediated protection of myogenic cells from transient energy deprivation. hsp alleviates the stress-induced inhibition of jnk dephosphorylation, j. biol. chem. ( ) – . http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf 	high resolution respirometry analysis of polyethylenimine-mediated
mitochondrial energy crisis and cellular stress: mitochondrial proton
leak and inhibition of the electron transport system
 	 . introduction 	 . materials and methods 	 . . materials 	 . . cell culture 	 . . live cell imaging and measurements of mitochondrial membrane potential in h cells 	 . . isolation of mouse liver mitochondria 	 . . high-resolution respirometry 	 . . . intact h cells 	 . . . freshly isolated mouse liver mitochondria 	 . . . ‘broken mitochondrial’ preparation 	 . . spectrophotometric analysis of civ activity 	 . . atp determination 	 . . trypan blue exclusion test 	 . . statistical analysis 	 . results 	 . . loss of Δψm precedes cell death in h cells on pei exposure 	 . . pei-mediated changes on mitochondrial respiratory states in intact cells 	 . . pei-mediated changes on respiratory states in freshly isolated mouse liver mitochondria 	 . . pei acts as a potent inhibitor of ets activity in ‘broken mitochondria’ 	 . . the effect of pei on intracellular atp levels and plasma membrane integrity 	 . discussion 	competing interests 	acknowledgements 	appendix a. supplementary data 	references a matter of energy stress: p β meets mtorc research highlight a matter of energy stress: p β meets mtorc adem kalender , anand selvaraj , george thomas division of hematology-oncology, department of internal medicine, metabolic diseases institute, college of medicine, univer- sity of cincinnati cell research ( ) : - . doi: . /cr. . ; published online april cell research ( ) : - . © ibcb, sibs, cas all rights reserved - / $ . www.nature.com/cr npg correspondence: george thomas e-mail: thomasg @ucmail.uc.edu throughout evolution, cells have developed sophisticated signaling mechanisms to balance the production and expenditure of energy to maintain energy homeostasis. during an energy crisis, cells suppress energy consum- ing anabolic processes and up-regulate basic catabolic routes to maintain the energy currency of the cell, adenosine triphosphate (atp). the main paths of atp generation are through gly- colysis in the cytoplasm and oxidative phosphorylation in mitochondria. a major consumer of cellular energy is the mammalian target of rapamycin (mtor) signaling pathway involved in the synthesis of proteins, ribosomes and lipids. mtor exists in two struc- turally and functionally distinct protein complexes, mtorc and mtorc , both are activated by growth factors and hormones, but only mtorc responds positively to nutrients and energy. initial studies using inhibitors of glycolysis or mitochondrial respi- ration revealed that mtor pathway responds to either energy source [ ]. a drop in atp production leads to the immediate inhibition of mtorc sig- naling within minutes, defined as the acute response, followed by a phase of recovery and then a second long term phase of inhibition, initiated within hours and termed the chronic response [ ]. inhibition of mtorc signaling through the chronic response is medi- ated by the transcriptional up-regulation of regulated in development and dna damage response (redd ) [ ]. in contrast, the widely accepted view is that the acute response is mediated by the amp-dependent protein kinase (ampk), either through the phospho- rylation and activation of the tuberous sclerosis complex / (tsc / ) [ , ] or through the phosphorylation and inhibition of the mtorc component raptor [ ] (figure ). however, recent loss of function studies demonstrated that acute mtorc inhibition by en- ergy deprivation, can be regulated in- dependently of ampk through the rag gtpases [ ] (figure ). likewise, lee et al. have reported that independent of ampk, glucose deprivation leads to glyceraldehyde- -phosphate dehy- drogenase (gapdh) binding of rheb and inhibition of mtorc signaling [ ] (figure ). in a recent study, zheng and col- leagues have brought a new player into the field of energy balance, the p pathway [ ]. the p pathway belongs to a mapk signaling module, a highly conserved pathway known for its role in stress responses, including those to pro-inflammatory cytokines and uv irradiation as well as heat and osmotic shock [ ]. there is a body of evidence showing crosstalk between the p and the mtorc pathways [ , ]. the role of the p pathway in global stress responses prompted zheng and colleagues to investigate whether p regulates mtorc , fol- lowing an energy deprivation episode. initial analysis employing p knockout mouse embryonic fibroblasts (mefs) revealed that p β was as an essential negative regulator of mtorc during energy deprivation crisis induced by -deoxy-d-glucose ( -dg), a glyco- lytic inhibitor. the authors then dem- onstrated that these effects were medi- ated by p β-activated kinase prak. similar to -dg, mtorc inhibition by glucose deprivation was also found to be dependent on the p β–prak cas- cade. the authors further demonstrated that ectopic expression of prak inhib- ited mtorc in the absence of tsc , whereas ectopic expression of tsc inhibited mtorc in the absence of prak, indicating that prak and tsc operate in parallel pathways to inhibit mtorc . however, it is important to note that -dg-induced mtorc in- hibition is impaired in tsc knockout cells despite normal activation of the p β–prak cascade. conversely, -dg activation of ampk was unable to inhibit mtorc in prak knockout cells. this would suggest that upon -dg treatment, p β–prak pathway and ampk-tsc / pathway might operate on a common downstream ef- fector to inhibit mtorc . interestingly, -aminoimidazole- -carboxamide -β-d-ribofuranoside (aicar), an ampk activator triggers the p β– cell research | vol no | june npg prak cascade in the absence of ampk and tsc . however, it was not demon- strated whether prak activation led to mtorc inhibition in these settings. the absence of such evidence leaves the question unresolved as to whether p β–prak cascade is dependent on ampk. this is a critical issue as others have shown that aicar, but not glyco- lytic or mitochondrial respiratory inhibi- tors, suppresses mtorc signaling in an ampk-dependent manner [ ]. how does prak inhibit mtorc signaling? earlier studies showed that fusion of raptor with the c-terminal amino acid portion of ras homolog enriched in brain (rheb), the small gtpase critical for mtorc activa- tion, leads to lysosomal localization of mtorc and its constitutive activation [ ]. zheng et al. found that ectopic ex- pression of prak inhibited mtorc activation by the raptor-rheb variant as well as that induced by ectopic ex- pression of wild-type rheb, raising the possibility that prak acts directly on rheb. immunoprecipitation and kinase assays showed that prak can bind and phosphorylate rheb, with the sites of phosphorylation identified as t and s . mutational analysis revealed that s was the critical site by which prak negatively regulated rheb func- tion, and following -dg treatment, this site was shown to be phosphorylated in cultured cells in a prak-dependent manner. importantly, overexpression of a rhebs a mutant prevented -dg-induced mtorc inhibition and ectopic expression of prak could not suppress mtorc activation by this mutant. mechanistically, these findings were consistent with in vitro guanine nucleotide binding assays showing that rheb phosphorylation results in decreased guanine nucleotide binding. further in vitro experiments showed that s phosphorylation caused gtp to be more readily released from rheb, and consistent with this, studies in cultured cells demonstrated a -fold reduction in nucleotide binding of rheb in wild- type mefs upon -dg treatment, as opposed to no effect in prak-deficient cells. this represents a novel mode of regulation of rheb function, since only changes in gtp hydrolysis [ ] or its sequestration by other proteins have been documented [ ]. since the nucleotide binding capacity of the rheb mutants was distinct, it was not pos- sible to accurately evaluate the effect of phosphorylation on gtp hydrolysis [ ]. an intriguing observation made by the authors is the dependency of glycolytic inhibitors, but not mitochondrial respi- ratory inhibitors, on prak. as noted earlier, inhibition of either pathway is anticipated to decrease intracellular atp pools and therefore a pathway that is responding to changes in atp levels would be expected to play a role in both settings to inhibit mtorc signaling. given this reasoning, it will be of in- terest to know whether mitochondria respiratory inhibitors also activate p β–prak cascade and increase rheb phosphorylation. it should also be noted that the regulation of mtorc signaling by energy-depleting agents, particularly metformin and phenformin, was shown to be dependent on the rag gtpases [ ]. in the light of the results obtained by zheng et al., it will be important to determine the role of p β–prak cascade in relation to that of the rag gtpases and whether these two pathways are integrated with one another or whether one pathway is uniquely used depending on the type of energy stress. a number of issues remain unan- swered in the field, which will prompt future studies. for instance, inoki et al. demonstrated earlier that high con- centrations of -dg caused osmotic shock, which led to the down-regulation of mtorc signaling in a tsc - independent manner [ ]. zheng et al. reported now that high concentrations of sorbitol did not require prak protein to down-regulate mtorc signaling [ ]; arguing that either pathway may substitute for the other or that osmotic shock alters mtorc signaling through yet another pathway whose identity is unknown. likewise, guan and col- leagues reported earlier that p -mk , unlike p β–prak cassette [ ], posi- tively regulates mtorc signaling by phosphorylating tsc [ ]. it will be of interest to elucidate upstream events by which these distinct and opposing roles of p are involved in regulat- ing mtorc function. finally, it was reported that mtorc inhibition by either glycolytic or mitochondria respi- ratory inhibitors is transient and that the activity of mtorc recovers over time figure model depicting the pathways that are involved in regulation of mtorc during energy crisis. broken lines indicate the absence of evidence for a critical role in the energy response. aas, amino acids; prheb, phospho rheb. www.cell-research.com | cell research npg due to compensation of the alternative energy source [ ]. it is surprising that in this new study such a transient ef- fect on mtorc signaling upon -dg treatment was not observed [ ]. the discovery by zheng et al. adds yet another layer of regulation of mtorc signaling by energy levels that highlights the importance of the cell’s need to maintain tight energy homeostasis by strictly fine tuning ma- jor energy consuming processes. this study represents a third instance of a mechanism regulating mtorc by energy levels that argues to function independently of ampk, the cell’s master energy gauge [ , , ]. finally, energy-depleting agents such as -dg and metformin are the object of clinical trials to evaluate their therapeutic poten- tial for the treatment of cancers since many tumors present a hallmark for be- ing highly dependent on glycolysis and energy levels on the whole. therefore, a deeper understanding of the different facets of regulation of mtorc by energy levels will be very valuable. acknowledgment we thank dr brian wiczer for critically reading the manuscript. references dennis pb, jaeschke a, saitoh m, fowler b, kozma sc, thomas g. mammalian tor: a homeostatic atp sensor. science ; : - . kalender a, selvaraj a, kim sy, et al. metformin, independent of ampk, inhibits mtorc in a rag gtpase- dependent manner. cell metab ; : - . sofer a, lei k, johannessen cm, el- lisen lw. regulation of mtor and cell growth in response to energy stress by redd . mol cell biol ; : - . inoki k, zhu t, guan kl. tsc medi- ates cellular energy response to control cell growth and survival. cell ; : - . shaw rj, bardeesy n, manning bd, et al. the lkb tumor suppressor nega- tively regulates mtor signaling. can- cer cell ; : - . gwinn dm, shackelford db, egan df, et al. ampk phosphorylation of raptor mediates a metabolic checkpoint. mol cell ; : - . lee mn, ha sh, kim j, et al. gly- colytic flux signals to mtor through glyceraldehyde- -phosphate dehydro- genase-mediated regulation of rheb. mol cell biol ; : - . zheng m, wang yh, wu xn, et al. in- activation of rheb by prak-mediated phosphorylation is essential for ener- gy-depletion-induced suppression of mtorc . nat cell biol ; : - . cuadrado a, nebreda ar. mechanisms and functions of p mapk signalling. biochem j ; : - . li y, inoki k, vacratsis p, guan kl. the p and mk kinase cascade phosphorylates tuberin, the tuberous sclerosis gene product, and enhances its interaction with - - . j biol chem ; : - . cully m, genevet a, warne p, et al. a role for p stress-activated protein kinase in regulation of cell growth via torc . mol cell biol ; : - . sancak y, bar-peled l, zoncu r, markhard al, nada s, sabatini dm. ragulator-rag complex targets mtorc to the lysosomal surface and is necessary for its activation by amino acids. cell ; : - . garami a, zwartkruis fj, nobukuni t, et al. insulin activation of rheb, a me- diator of mtor/s k/ e-bp signaling, is inhibited by tsc and . mol cell ; : - . 	a matter of energy stress: p β meets mtorc 	acknowledgements 	references wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ intelligent street lights procedia technology ( ) – available online at www.sciencedirect.com sciencedirect - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of amrita school of engineering, amrita vishwa vidyapeetham university doi: . /j.protcy. . . smart grid technologies, august - , intelligent street lights y m jagadeesha, s akilesha, s karthika*, prasantha apanimalar engineering college, chennai - , india abstract in today’s world, more amount of electricity is consumed due to street lights. this is due to continuous operation of lighting during the night time. in order to reduce the electricity consumption and wastage of energy, the system that has to combine the existing network with intelligence to think itself. this newly developed concept will enable the street lights to adjust automatically based on the real time traffic conditions and change according to naturalistic condition (full moon). this paper is concerned with the development and implementation of low cost sensor based street lights with dynamic which in turn reduces the energy consumption and co emission. it consists of ir sensor, pir sensors, low cost embedded controller and storage device. © the authors.published by elsevier ltd. peer-review under responsibility of amrita school of engineering, amrita vishwa vidyapeetham university. keywords: lighting control; dynamic control; sensor; detection; embedded controller; energy crisis; . introduction electricity is one of the common demands for the people among the world, though it can be produced but it is not satisfying the exact demand. to overcome this, electricity during unused hours must be saved and it is very hard for the human to monitor and control. in today’s world, % of the electricity produced is used for the street lighting due to its continuous operation during night time. in order to minimize the electricity consumption, wealthy technology has to be implemented for the street lighting system. this paper discusses about the dynamic street lighting system, which reduces the wastage of energy and co emissions. the system would intelligently adapt the lighting levels based on the weather conditions and traffic density. these lighting levels or intensity will be adjusted dynamically through the sensors and microcontroller according to the current density of the lane. an external feature has also been included in this system, so that street lights will adapt lightning based on the naturalistic features like full moon day, lights will glow half of its normal intensity. *corresponding author. tel.: . e-mail address: karthik.dec @gmail.com © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of amrita school of engineering, amrita vishwa vidyapeetham university y.m. jagadeesh et al. / procedia technology ( ) – . architecture of smart street light fig. ir and pir sensors in lane the architecture consists of several ir and pir sensors placed at both the ends of the lane to detect the density of passersby. these sensors are placed at a certain distance and it transfer the information among itself when is vehicle is detected. the sensors communicate with each other through wired connection. here wired connection is used in order to reduce the cost. the implementation of smart and dynamic street lighting system provides an easy way to reduce the energy consumption and co emission. this system has the capability of real time flow control. each sensing part consists of both infrared and pir sensors to detect the flow. in this two sensors are used to improve it accuracy of detection. these sensors are connected to the microcontroller in which data has been processed and adjust the lighting levels. whenever the passer is identified by sensor, it will communicate to neighbouring street lights, which will brighten the surrounding lights. the street lights will dim to low voltage level when no activity is identified and brightens to high voltage level when movement is detected. due to increase in industries, this system will play major role in saving the electricity without affecting the comfort zone. fig. shows the schematic diagram of dynamic street lighting system with ir and pir sensors in lane. . block diagram of dynamic street lights fig. shows the block diagram of dynamic street lighting system. the block diagram consists of various subsystems like sensing unit, microcontroller unit and the lighting system. the sensing unit consists of both ir and pir sensors to detect the density of the lane. low power microcontroller is attached with sensing unit to adjust the intensity level of lighting based on density. the microcontroller is connected to the lighting system. this whole unit gets powered from the batteries. the sensing unit will prescribe internal communication for the clearance of lights along the path. y.m. jagadeesh et al. / procedia technology ( ) – fig. . basic block diagram of dynamic street lighting system . detection and street light control . detection unit detection unit consists of infrared sensors and passive infrared sensors on each side of the lane which detects the density or flow of the lane and sends the data to the microcontroller for processing. these sensing units are placed on both sides of the road to an individual operation on each side. these sensing units will communicate each other during its operation. when a person is detected in lane it brightens the lights and also brightens its neighboring lights, so that person can be surrounded by safe circle of light. this is achieved due to communication between the sensors. this dynamic control of street lights overcomes the wastage of electrical energy which is the most needed in today energy crisis. in this dynamic control, the detection unit plays an important role to sense the density of the lane and perform corresponding actions through microcontroller. . street light control through computing from the sensing unit, the data is transferred to the microcontroller in which dynamic control of street light is performed, the flow chart of which is given in fig. . fig.. flow chart of dynamic street lighting system y.m. jagadeesh et al. / procedia technology ( ) – the flow chart describes about brightness control in the dynamic street lighting system. initially all the values about the density are read through sensing unit. at first it checks that is there is any movement in the lane then it divides into two sub division. i. if there is any movement of data then the lights glows at its higher brightness and communicate with neighbouring sensor to brighten the nearby lights. ii. else the lights will glows to the quarter of its original brightness and communicate with neighbouring to do the same operation. therefore the system allows high brightness for higher density and less brightness for lower density. the line with the less density flow will save the electricity for future and reduces the co emissions. in this system, the counter control of street lights is also included. the counting operation is performed in the microcontroller itself. there will be a full moon day in every days. the counter is made to run whenever the counter reaches the multiples of then the light will dim to of its original brightness. the implementation of the system in city explores % of electricity savings and thereby reduction in co . . experimental setup . density detection the sensors are placed at both ends of the road. it consists of both infrared and passive infrared sensors. these sensors are used to detect the density of the lane. these sensors will give digital output which is either v or v depends upon the detection. suppose if the movement is detected in the particular lane it gives output of v else output voltage is . these output values are processed through atmega microcontroller. the microcontroller is programmed to analyze the density of the lane and gives a dynamic control to the intensity of street lights. by this system, the street lights can think of themselves and adjust the intensity of lights. the street lights will be turned off and on automatically by using light dependent resistors. in this system, microcontroller remains in the sleep mode during day time and switches to active mode during dark period. this operation is made automatic by the witness of natural light. . microcontroller and lighting control the microcontroller act as a common to all the sensing units but lighting control is achieved individually for every sensor for the better accuracy. the density of the lane is detected through sensing unit and received to the microcontroller. this microcontroller performs the dynamic light intensity control and transfers the signal to the lighting system. this dynamic control is achieved through pulse width modulation in atmega . normally the lighting systems are of led and sodium vapour lamps . working concept initially ir and pir sensors are laid on both sides of the roads based on the density of movement. these sensors are connected to common microcontroller. for a single street a single microcontroller is enough to perform the operation. the sensor senses the data about the density of the lane and transfers the signal to the microcontroller. each and every lane has its sensors which establish internal communication between them. the microcontroller fetches the instruction from the sensing unit and analyzes the density of the lane which in turn controls the intensity of street lights. the small model of the system is shown in the fig. . the microcontroller processes the data as per the flow chart. these processed signals are transferred to the lighting system in which the intensity of light is varied. it transfers the signal to the nearby light to perform the necessary action based on the movement. y.m. jagadeesh et al. / procedia technology ( ) – fig. simulation output of microcontroller for dynamic street lighting system . results the result includes the successful operation of dynamic street lighting system. it reduces the wastage of energy in unused hours. this system controls the intensity of the lights based on the density of lane. this system can also be called as intelligent street lights or smart street lights which think of themselves. . conclusion this paper presents the low cost intelligent street light system through sensors for the reduction in electrical energy. this dynamic street lighting system is experimented through ir and pir sensors and the outputs are obtained through proteus simulation software. by introducing this system, the energy crisis in today’s world can be reduced to some extent. references [ ] wu yue; shi changhong; zhang xianghong; yang wei, design of new intelligent street light control system, control and automation (icca), th ieee international conference on, p. , , - june . [ ] xingming long; jing zhou, an intelligent driver for light emitting diode street lighting, automation congress, . wac . world , vol., no., p. , , sept. -oct. . [ ] mendalka, m.; gadaj, m.; kulas, l.; nyka, k., wsn for intelligent street lighting system, information technology (icit), nd international conference on , vol., no., p. , , - june . [ ] nefedov, e.; maksimainen, m.; sierla, s.; chen-wei yang; flikkema, p.; kosonen, i.; luttinen, t., energy efficient traffic-based street lighting automation, industrial electronics (isie), ieee rd international symposium on , p. , , - june . [ ] deo, s.; prakash, s.; patil, a., zigbee-based intelligent street lighting system, devices, circuits and systems (icdcs), nd international conference on , vol., no., p. , , - march . [ ] adrian, l.r.; ribickis, l., intelligent power management device for street lighting control incorporating long range static and non-static hybrid infrared detection system, power electronics and applications (epe' -ecce europe), th european conference on , p. , , - aug. . [ ] srivatsa, d.k.; preethi, b.; parinitha, r.; sumana, g.; kumar, a., smart street lights, india educators' conference (tiiec), texas instruments , p. , , - april [ ] leccese, f. , remote-control system of high efficiency and intelligent street lighting using a zigbee network of devices and sensors, power delivery, ieee transactions on, p. - volume: , issue: , jan. [ ] yang tao; lingbo kong; yinyang wang; hu jian-bin; chen zhong "pku-straw-l: a simulative platform evaluate the power-saving rate of the intelligent street lamp system", ubiquitous intelligence & computing and th international conference on autonomic & trusted computing (uic/atc). news from the iaeh letter from the new iaeh president, jakob zinsstag: health & ecology: let us join forces my parent’s generation, years ago, still assumed that the capacity of resilience of the planet could not be exhausted and that human activity was negligible com- pared to the gigantic force of ‘‘mother nature’’. they perceived nature often as hostile to humans through floods, earthquakes, avalanches, or volcanic eruptions. such perceptions maintained a rather defensive attitude against our natural environment, seeing it only as a risk to human health. however, with the exponentially growing world population, increasingly noticeable water, soil, and air pollution led to the development of envi- ronmental laws, a converging international consensus, and ultimately the rio summit and kyoto protocols of the past decades. the current global status is highly dynamic, socially, economically, or ecologically. we approach with many unfulfilled promises of the millenium development goals amidst an unsolved economic crisis. there is per- sistent disappointment over the lack of more tangible international environmental consensus as seen at the rio+ conference this year. there is less and less doubt about the anthropogenic drivers of climate change, leading among others to a doubling of natural disasters in the last decade as compared to those before. the looming energy crisis is not only about reducing carbon emissions or attempting to walk out of the nuclear threats that we have witnessed dramatically in fukushima. access to affordable and renewable energy is critical to social development, with the poorest nations relying the heaviest on fossil fuels. demographic growth remains strongest in the poorest areas of the world, mainly in africa. we recognize more and more the inextricable linkage of health of humans and animals and their ecosystems and understand that neither humans nor animals can lead a healthy life on a threatened planet, unable to provide any longer its necessary ecosystem services such as clean water and fertile land. attempts to mitigate these syndromes of global change cannot be achieved by single disciplines and require us to join forces. less than a decade ago, a handful of scientists from many different fields converged to take the ecosystem health movement forward, creating a scholarly association, the international association for ecology and health (iaeh, www.ecohealth.net). the aims of the iaeh in linking health and wellbeing of all species with ecosystem determinants have moved our field clearly beyond linking human and animal health as ‘‘one health’’, and beyond an environmental health approach that is limited to environmental risk assessment. scientists engaging with ecohealth thinking have opened new inte- grative research pathways across academic disciplines, ecohealth , – , doi: . /s - - - news from the iaeh � the author(s). this article is published with open access at springerlink.com http://www.ecohealth.net linking science and society through participatory stake- holder processes. they defy reductionism of individual disciplines and promote reflexive and systemic approaches to the complex problems of the contemporary world including its necessary philosophical underpinnings. however, this new and innovative way of looking at the complexity of contemporary health and ecological issues is still represented by only a small and scattered group across the world. health and wellbeing of humans and animals act as a seismograph of our planet earths moods and tempers. ecosystem integrity is about the health of us all. our adolescent iaeh needs to stand upon stronger institutional feet and to unite forces with as many related movements as possible. my vision for a maturing iaeh is that over hundred academic and research institutions may join forces as institutional members of the association, so that we can raise our political profile and influence analogous to the intergovernmental panel on climate change (ipcc), and actively contribute to the shaping of international policy. this can be achieved through excellence in integrative health and ecological research, mirrored through our journal ecohealth, which continues to raise its scientific quality. this is a wide open field for innovation. for example, could we move towards ecological certification of health systems, providing ade- quate and equitable health care within a , w energy limit world wide? could we act as the guiding organization for re-focusing one health efforts in a more ecological context? could we provide the background for policy makers concerned about pandemic prevention to demonstrate that most pandemics originate in the interplay between envi- ronmental change, human behaviour and pathogen evo- lution? these goals cannot be achieved alone and i look forward to all your collaborations, contributions, and constructive criticisms during my biennial term as iaeh president. with kind regards jakob zinsstag swiss tropical and public health institute, basel president, international association for ecology & health open access this article is distributed under the terms of the creative commons attribution license which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. published online: february , 	news from the iaeh 	open access layout energy security and economic growth in pakistan tahir mahmood* and muhammed tayyab ayaz** abstract energy is a crucial input in the process of economic growth. sustainable economic growth neces- sitates the sufficient and continuous availability of energy. pakistan is confronting energy insecurity which is seriously hindering the economic development and this study is an attempt to investigate the relationship between energy security and economic growth. the major concern of energy se- curity is associated with the availability of suitable energy supply in cheap and consistent way to fulfill energy demand in the future. in this study, the demand and supply gap of energy is used as a proxy variable for energy security. the data source is the energy information administration (eia) where data is available at disaggregate level for different sources of energy (i.e., oil, gas, coal and electricity) for the period of to . therefore, aggregate variables are generated by converting data into unified unit of measurement. the error correction model (ecm) is used to analyze the short-run and long-run causality between energy gap and the economic growth. the results show that unidirectional causality runs from energy demand and supply gap to economic growth in short-run as well as in the long-run. this relationship is negative and statistically signif- icant in both the short- run and the long run which indicates that low energy security (i.e., increasing energy gap) halts the economic growth of pakistan. consequently, the study concludes that gov- ernment should focus on better management of energy demand and energy supply. key words: energy demand, energy supply, energy security, economic growth, time series. jel classification: o , q , q . i. introduction energy security is defined as, ‘it is reliable and suitable supply of energy at rea- sonable prices’ [belicki ( )]. reliable and suitable supply indicates the continuous supply of energy in order to fulfill its demand. the major concern of energy security is associated with the availability of suitable energy supply at cheap and in consistent way to fulfill energy demand in the future days; while, worries for energy security was first felt after the s oil price shock, but some energy economists believed that is- sues related to energy sector were solved through market, and there was no need to pakistan journal of applied economics, vol. no. , ( - ), summer *assistant professor, **research scholar, school of economics, quaid-i-azam university, islamabad, pakistan. worry about the energy security. however, the continuous high oil price period came back again and the equilibrium of energy demand and supply again diverted attention of the world towards increasing the energy security. many energy economists and the governments believe that energy insecurity problem would not be solved without the demand side management [bhattacharyya ( )]. for developing countries, it is essential to manage the energy demand because their share in the energy demand is more, as compared to the developed countries. according to the world economic outlook ( ), the worldwide energy demand is estimated to increase at the rate of . per cent, during to ; where the share of asian devel- oping countries in this demand will be around per cent. in the primary energy demand in the non-oecd countries would increase to per cent. the energy demand of the world would remain to around per cent during to . in , the in- vestment of us$ trillion, were needed for the energy sector. energy crisis is a severe issue in the south asian countries because due to increase in population of the whole re- gion its energy demand increases on daily basis. saez ( ) contends that future energy consumption of south asia will increase further due to the demographic trends. increase in energy demand of pakistan, india and bangladesh will be a threat to their energy se- curity because the south asian countries did plan to increase their energy supply and thus their shortfall gap become wider between the energy demand and its supply. energy security plays a very important role for growth in transitional economies, such as pakistan and energy demand and supply gap is increasing in the country. the electricity crisis for the last three decades is a failure of government, poor administration of the institutions, besides corruption in the energy sector. as a result of the current power outage situation the country is not only creating problems for residents/households but is also the cause of many industries shutdown. this will decrease the production and slow down the economy [kessides ( )]. according to valasai, et al. ( ) there are many energy security concerns for pakistan. electricity shortfall is major issue of the country because of the increasing energy gap which further widens in the summer sea- sons. during the last decade, power shortage in the country varies from to hour in urban areas and for more than hours, in rural areas. this shortfall is due to low invest- ment and the political instability of ruling governments. this study also finds that due to global problem in supply, pakistan is facing a challenge of meeting its electricity demand. the study suggests that policy makers should review their current strategies to minimize the electricity gap of supply and demand of the country [valasai, et al. ( )]. the main objective of this study is to analyze relationship between energy security and economic growth in pakistan. for this purpose the energy demand and supply is used as a proxy variables for energy security. the error correction model (ecm) is used to analyze the short-run and long-run causality between energy gap and economic growth. the results show that, unidirectional causality exists from energy demand and supply gap to the eco- nomic growth. this relationship is negative and statistically significant in both the short-run and in long-run, indicating that low energy security halts economic growth of pakistan. pakistan journal of applied economics the rest of paper is organized as follows: section ii presents the theoretical and graph- ical analysis of energy sources of pakistan; section iii outlines the literature review on energy security and economic growth; and section iv explains the methodology and es- timation procedure. data set is presented in section v and section vi presents the results. in the last part of the paper, section vii concludes the discussion with policy suggestions. ii. energy sources of pakistan according to the u.s. energy information administration (eia) the energy demand share of pakistan in different energy sources was around per cent in coal, per cent in electricity, per cent in petroleum, and per cent in natural gas (table ), during the period to . power and transport sectors are leading consumers of oil; there- fore, oil and natural gas are the two major sources of energy, covering per cent of the energy demand in pakistan. in the past, the energy supply share of pakistan was ap- proximately per cent in coal, per cent in electricity, per cent in petroleum and per cent in natural gas. this statistics shows that pakistan energy depends more on pe- troleum and natural gas. . coal figure shows the demand and supply of coal (in quadrillion btu) in pakistan. it demon- strate very interesting results that during to coal demand was less than its supply, but between to its demand was greater than its supply, because as compared to con- sumption of coal our domestic production was low in this period. from onwards the con- sumption and supply of coal was almost the same, because thereafter its consumption decreased after . the economic survey of pakistan - coal resources of pakistan were around billion tones, which were estimated at per cent of the world coal reserves. the government of pakistan believes that coal expansion is very necessary for energy security. the main objec- tive of ‘vision ’ is to increase its production and use it in power generation. mahmood and ayaz, energy security and economic growth in pakistan energy source energy demand energy supply coal per cent per cent electricity per cent per cent natural gas per cent per cent petroleum per cent per cent table energy demand and supply share of pakistan for the period to source: https://www.eia.gov/beta/international. https://www.eia.gov/beta/international. pakistan economic survey, government of pakistan, ( - ). . oil figure shows the demand and supply of oil (petroleum). from to the demand of the petroleum was greater than the supply of the country, but due to increase in crude oil prices the demand of oil showed a substantial decline during to . in the average price of oil was us$ . /barrel but in it increased to us$ . /barrel; which was more than double as compared to the price of . the crude oil price was at its highest (record) prices of us$ /barrel in pakistan journal of applied economics . . . coal supply . coal demand figure coal demand and supply . . oil supply . oil demand figure oil demand and supply source: authors’ vision. source: authors’ vision. . due to this volatility in prices the annual petroleum consumption started shift- ing to other energy sources i. e., coal, electricity and gas [economic survey of pak- istan ( - )]. in , the oil share started rising again, because of the gas load management and decrease of oil prices. the oil prices fell to its lowest level of us$ /barrel level in february . the fall in oil prices tends to increase inter- national savings and people would spend this saved money on consumption of other goods and services. . electricity in pakistan, electricity is the secondary source of energy which is essential for household consumers as well as the other domain like transport industry, etc. the elec- tricity sector face many problems due to power generation theft, inadequate accumu- lation rates, line losses, undersupply and very high subsidy on natural gas. these issues have brought the financial losses for generation companies which leads to widespread the power shortage. load shedding is the major concern of the people of pakistan be- cause it is not only creating disturbance for the society but it also, worsen the economy and real gdp growth rate. figure shows the electricity supply and demand in quadrillion btu, from - . it indicates that electricity supply is more than its demand but in spite of that pakistan is facing heavy shortfall of electricity; due to transmission and dis- tribution losses of electricity. malik ( ) argues that in - electricity dis- tribution and transmission losses were around per cent, which was entirely higher mahmood and ayaz, energy security and economic growth in pakistan . . electricity supply . electricity demand figure electricity demand and supply source: authors’ vision. than the other asian countries. transmission and distribution losses in china are per cent and in korea they are . per cent. according to the international energy agency (iea), the installed capacity of electricity in pakistan is , megawatt (mw) and the annual electricity demand of the country is , mw; whereas, the available capacity of electricity is only , mw, which is far behind the electricity demand of pakistan. . natural gas natural gas is one of the most established energy sectors of pakistan; and its distribution system is also very well settled, throughout the country. the natural gas supply and demand remained unchanged from to (figure ); but due to increase in the share of energy usage, the difference in its demand and supply increased suddenly. this gap started when there was high increase in petrol prices in - ; and also, because of cheap price of gas people substituted to use gas against petrol. according to the pakistan economic survey - , it was esti- mated that during the fiscal year of - , roughly , new consumers were entitled for the gas connection, which was also given, as well. pakistan natural gas production was million cubic feet and the demand of natural gas was million cubic feet, which was expected to increase to million cubic feet by - . due to reduction in the natural gas resources there is a threat for the sector because finding of new gas resources is very sluggish. pakistan journal of applied economics figure natural gas demand and supply note: demand and supply of natural gas is in quadrillion btu ( - ). source: authors’ vision. natural gas supply natural gas demand iii. literature review energy is considered to be a central input in the process of economic growth. sustainable economic growth necessitates sufficient and continuous availability of energy input [kraft and kraft ( ), yu and hwang ( ), stern ( )]. many energy economists investigated the relationship between energy usage and economic growth. their views, opinions and arguments differ and lead to occurrence of different results. these studies used diverse econometric techniques to investigate the relation- ship between energy and economic growth, and therefore, their results were dissimilar. some studies found that no relationship exist between energy usage and the economic growth [yu and hwang, ( ), and stern ( )[; while, others found that the bidi- rectional causality exist between energy and growth [soytas and sari ( ), and ghali and el-sakka ( )]. however, from the pakistan's perspective, energy is one of the main determinants of economic growth. studies by kakar and khilji ( ), and chaudhary, et al. ( ) found a unidirectional causality running from energy consumption to economic growth. another study by shahbaz and feridun ( ) ob- served a long-run relationship between the power consumption and economic growth. during the time period of to the energy demand is expected to increase by per cent, and on the other hand, global energy supply is facing many challenges. due to these imbalances in energy supply and demand the energy security is at stake. the extent to which the energy security relates to economic growth has received a lot of attention in the economic literature [lu, et al. ( ), cherp and jewell ( ), and awan and khan ( )] which give theoretical framework on relationship be- tween the energy security and economic growth. this study, empirically investigate the energy security and economic growth in pakistan; the road map is that by its economic growth would recover, gradually to . per cent. further progress de- pends on tackling the key growth constraints, such as frequent energy shortage. the current energy crisis in pakistan arises due to the rising trend in energy supply and the demand gap. therefore, due to this gap energy security is at risk in pakistan. the focus of the state is on the supply side; but the energy efficiency and energy conser- vation (eeec) policy can reduce the demand of energy which would be more cost- effective, than increasing the energy supply. for energy security of pakistan, it is also important to use the alternate energy sources and increase the domestic energy pro- duction. the energy supply and demand is not only important for economic prosperity but it is also essential for the society’s living standards [khalil and zaidi ( )]. due to power shortage in pakistan the economic growth is affecting adversely, in all spheres of peoples’ lives. electricity is the major source of energy sector, which is going through the worst condition. as a result of this crisis, socio-economic and industrial growth slowdown in the country, will lead to affect the economy of pak- istan and create many other problems, like unemployment and poverty. the best way to solve this calamity is to use alternative energy resources which will not only solve mahmood and ayaz, energy security and economic growth in pakistan the current energy crisis but will also reserve the energy security for future genera- tions of pakistan. if government follows its target of national energy security plan (nesp), then this issue might be solved early [shaikh, et al. ( )]. in order to im- prove the living standard of people, the focus of government should shift towards the renewable energy, because it plays a significant role to get rid from the electricity crisis of the country. for progress of any country, industrial growth is very important but it depends on consistent supply of energy while, pakistan is going through the energy crisis which will badly affect the people lives [awan and khan ( )]. iv. methodology . theoretical model the relationship between energy and economic growth is complex. some re- searchers believe that energy is not the part of production because it has small cost share while others believe that energy is a fundamental part of production function. the study by ayres, et al. ( ) and vlahinic and zikovic ( ) found that energy is as important as labor or capital in economic growth. it is not possible for labor and capital to function without the use of energy. stern and cleveland ( ) and provoski ( ) showed the relationship between energy and economic growth, and explained that energy plays a very vital role in economic growth. the human work can be re- placed by other appliances/machinery with the help of energy sources. the construction of new production theory with addition of energy factor in pro- duction function has many benefits. it explains the structure of growth by stating the peripheral sources of energy, if the solow ( ) argument can be used, i.e., “to show the endogenous segment of innovative advancement as a necessary part of the hypoth- esis of economic development.” the production factor has three factor of production; capital, labor and energy. capital and labor are predictable while energy can explain the productivity growth. y = f (k, l, e) ( ) the above production function shows that output is a function of capital, labor and energy; whereas, in many economic studies energy is not utilized effectively. en- ergy is a preserved quantity which is not replenished, or it will run out in the economic process, or it will not be included in the factor of production. therefore, energy is re- placed by the exergy. this refers to as part of energy which is used in the economic process. the major difference between exergy and energy is that exergy is not the con- served quantity [nokicenovic, et al. ( )]; whereas, some studies illustrate that en- ergy is used in the factor of production and, it plays an important role in economic development [ebohon ( ), and stern and cleveland ( )]. pakistan journal of applied economics mahmood and ayaz, energy security and economic growth in pakistan although, energy is an important input in production process, it is also considered as one of the main determinants of economic growth. however, it could have adverse effect on developing economies where energy demand is higher than the energy supply, and therefore the governments have to depend on energy imports. in these developing economies, an increase in demand of energy could enlarge the energy demand and supply gaps. these gaps may have potential to halt economic development in the long- run. a study by asafu-adjaye ( ) supports the above argument and observed that in thailand and philippine, increase in energy consumption does not raised the eco- nomic development, because (at that time) the energy supply of these countries was less than the energy demand. another study by aqeel and butt ( ) observed neu- trality hypothesis between energy consumption and economic development in pak- istan, and specified that increase in energy consumption does not affect economic growth because of energy shortfall in the country. however, in developed countries where energy gaps are small, adding more energy demand may increase the economic growth. in established countries like sweden, canada and usa, increase in energy usage will lead to increase the economic devel- opment [ghali and el-sakka ( ), chima and freed ( ), and stern and enflo ( )]. in these countries energy demand affects economic progress positively, in the long run; as they focus on energy supply and manage their energy sector more effi- ciently as compared to the developing countries. the transmission and distribution loss in developed countries is very low as they make policies which reduce the the en- ergy demand. hence, the argument that high energy insecurity (i.e., energy gap> ) could halt economic growth in the long-run and can be tested for pakistan by following the estimation procedures. . estimation procedure relationship between energy security and economic growth pakistan is a developing country where energy gaps are high, due to energy supply constraints and the rising energy demand. in this study energy gaps are used as proxy for energy security. therefore, it is necessary to analyze the relationship between these energy gaps and the economic growth. as a first step, the augmented dickey fuller (adf) and phillips-perron (pp) tests are used to find the order of integration of gdp and the energy gap. since both these series are non-stationary in nature, they may have long-run or co-integrating relationship. therefore, these series can be represented and estimated in the following error correction model (ecm). m m ^ ln yt =  +   ln yt-p +   ln egapt-p +  et- + ut ( )p = q = m m ^ ln egapt =  +   ln yt-p +   ln egapt-p +  et- + vt ( )p = q = pakistan journal of applied economics the variable is the growth rate of gdp and ln egapt is the growth of energy gap at time period t; and êt- is one period lag of residuals from the long-run co-in- tegrated relationship (ln yt =   ln egap + et) which is estimated using fully mod- ified ordinary least squares. t-test on the point estimate for  [from equation ( )] would be a test on long-run granger-causality from egap to y, and accordingly, a t-test on the point estimate for  [from equation ( )] would be a test on long-run granger-causality from y to egap. the simultaneity of economic growth and energy security needs a specific analysis that gives role to the two-ways predictability evident. the error correction model is used to find the short-run and long-run, as well as the causality between energy gaps and gdp with time series data from pakistan, for the years to . on the assumption that lag length m is correctly specified by using aic in the short-run causality, the variable energy ln egap says no to granger cause. vari- able ln y which is not significantly different from zero, if ( = for l = ,…, m). in other words, if history of ln egap does not improve the prediction of ln y, given the history of ln y; then the growth of energy gaps do not cause the growth rates of gdp. similarly, growth rates of gdp do not cause growth of energy gap, if in the energy gap equation  = for all l = , …, m. v. data and variable construction this section covers the internationally comparable energy information adminis- tration (eia) dataset for the period of to . it provides data on energy at dis- aggregate level (i. e., petroleum, natural gas, electricity and coal) in different units. all disaggregate data in the same unit of british thermal unit (btu) is converted. the unit conversion factor is as under: the data on gdp is taken from the world development indicators with constant us$. . the time period used for analysis was from to . in the second stage, energy demand and energy supply series were generated as under. . energy supply at aggregate level the international energy agency [iea ( )] is followed to make the energy supply function: description conversion factor cubic foot of natural gas = , btu kilowatt-hours of electricity = , btu barrel ( gallons) of crude oil = , , btu source: https://www.eia.gov/beta/international. est = ept + (eit - eet ) ( ) where, est is energy supply, ept is energy production, eit is energy imports and eet is energy exports at time t. . energy supply at disaggregate level a) electricity the data on electricity production, its import, export and consumption is taken from the u.s energy information administration (eia). the unit of data is billion kilowatt-hours, which is converted in quadrillion btu by using unit convertor. elecst = elecpt + (elecit - elecet) ( a) where, elecst is electricity supply, elecpt is electricity production, elecit is electricity imports and elecet is electricity exports. b) coal coal is also used for production, consumption, export and import to generate coal supply series. the data of coal consumption and production is available in quadrillion btu. we construct the supply of coal as follow: clst = clpt + (clit - clet) ( b) where, clst is coal supply, clpt is coal production, clit is coal imports and clet is coal exports at time t. c) natural gas natural gas is an established sector of pakistan. the distribution system of gas sector is well established. this study uses the natural gas consumption and production data which is also in quadrillion btu. its supply function is mentioned below: ngst = ngpt + (ngit - nget) ( c) where, ngst is natural gas supply, ngpt is natural gas production, ngit is natural gas imports, and nget is natural gas exports. d) petroleum products data on petroleum products is available in thousand barrel per day which is first transformed into annual data base and multiplied by days; thereafter, ot os con- verted in quadrillion btu. petrlst = petrlpt + (petrlit - petrlet) ( d) where, petrlst is petroleum supply, petrlpt is petroleum production, petrlit is pe- troleum imports and petrlet is petroleum exports. mahmood and ayaz, energy security and economic growth in pakistan pakistan journal of applied economics . energy demand energy consumption is used as a proxy variable for energy demand [wolde, ( )]. therefore, the total primary energy consumption is used as a proxy variable for energy demand. the data of total primary energy consumption is taken from the u.s. energy information administration (eia). edt = ngdt + electdt + cldt + petrldt ( ) where, edt is energy demand, ngdt is natural gas demand, electdt is electricity demand, cldt is coal demand and petrldt petroleum demand. . energy gap and energy security in this study, energy gap is used as a proxy variable for energy security. when there is a gap between the energy demand and supply increase, it indicates that en- ergy insecurity is increasing. the energy gap equation is given in equation ( ). e gapt = edt - est ( ) where egapt is energy gap and est is energy supply. vi. estimation and results . relationship between energy security and economic growth according to the theory of co-integration there is at least one long-run equilibrium relationship among existence of variables. in this case, granger causality exist among these variables in at least one way [engle and granger ( )]. in this study the error correction model (ecm) is used to analyze the long-run, as well as the short-run causalities between the energy security and economic growth. therefore, as a first step, there is a need to know the integration order of both series. the augmented dickey fuller (adf) and phillips-perron (pp) are used to test the unit roots. results of table shows that gross domestic product (gdp) and energy gap, both are inte- grated to order one [i ( )] because both series are stationary at first difference. based on the results of table gross domestic product yt and series of energy gap (egapt) are the best characterized as i( ), where the long-run or co-integrating relationship between these two series is followed. the residual series (êt) is generated from the long-run co-integrated relationship (ln yt =  +  ln egap + + et), which is estimated by using ordinary least squares. table shows the long-run relationship between the energy gap and gdp. mahmood and ayaz, energy security and economic growth in pakistan results of long-run equilibrium relationship presented in table shows the coef- ficient of energy gap (- . ) which is negative and significant at one per cent level of significance. this means that an increase of one per cent in energy demand and its supply gap will reduce gdp by . per cent for pakistan in, the long-run. after ex- amining the long-run relationship between energy gap and gdp the next step is to in- vestigate the direction of causality between energy gaps and economic growth in short-run and in the long run. for this purpose the error correction model (ecm) mo- tioned in section iv [equations ( ) and ( )], is used where, (êt- ) is a one period lag of residual from the long-run co-integrated relationship (ln yt =  +  ln egap + + et), which is estimated by ols. a t-test on point estimate for  [from equation ( )] would be a test on long-run granger-causality from egap to y, and accordingly, a t-test on point estimate for  [equation ( )] would be a test on long-run granger-causality from y to egap. results of table shows that coefficient of êt- () is negative and significant but the coefficient of êt- () is statistically not significant. therefore, significance of  shows the long-run granger-causality which runs from energy demand and supply gap (egap) to gross domestic product (y). test ln yt  ln yt ln egapt  ln egapt test value p value test value p value test value p value test value p value adf-test . . . . *** . . . . *** pp-test . . - . . *** . . . . *** table the results of unit root tests table results for long run relationship source: authors’ estimation. notes: automatic selection of lags based on minimum aic: – . ***, **, and * denote rejection of null hypothesis at , and per cent level of significance. source:authors’ calculations. ln yt =  +  ln egap + + et dependent variable: ln yt variable coefficient c . *** ln egapt - . *** no. of observations . r . on the other hand short-run dynamics also reveal that unidirectional causality runs from energy demand and supply gap to the economic growth. the coefficients on lag value of energy gap (- . *** and - . ***) are negative and statistically significant. this shows that an increase in energy gap (i.e., decrease in energy security) would de- crease the economic growth. the upsurge in economic growth is caused by decrease in energy security. the negative impact of energy demand and supply gap on economic growth could be a result of high energy demand or decreasing energy supply in pak- istan. this argument is supported by the asian development bank; and this study finds that due to increase in power shortages economic growth is decreased in pakistan by per cent. another study by morimoto and hope ( ) also found significant rela- tionship between electricity supply and economic growth in sri lanka. a study by khan and ahmed ( ) highlighted the role of rising energy demand and supply gap for economic growth and argues that energy consumption and production gap is one of the main determinants of slow growth of pakistan. due to increase in energy de- mand, energy security will be in danger in future. the government is focusing on short term policies, which will not fulfill the future energy demand of the country. vii. conclusion the objective of this study is to investigate relationship between energy security and economic growth in pakistan. energy demand and supply gap was taken as a proxy for energy security. data of energy (i.e., natural gas, coal, electricity and petroleum products) was taken at disaggregate level from the u.s. energy information admin- istration (eia). the disaggregated energy data was used to generate energy demand and supply gap at aggregate level; as the data was in different units it became one of the main obstacle which was solved by converting in same unit of british thermal unit (btu). in this study error correction model (ecm) is used to analyze long-run as well as the short-run causalities between energy security (i.e., energy demand and supply gap) and the economic growth. the results of long-run equilibrium relationship shows that an increase of one per cent in energy demand and energy supply gap will reduce the gdp by . per cent for pakistan in the long-run. it implies that economic growth is decreasing due to energy insecurity. after examining the long-run relationship between energy gap and gdp, the next step is to investigate the direction of causality between energy gaps and economic growth in short-run and the long run. the short-run dynamics also reveal that unidirectional causality run from energy demand, and the supply gap to economic growth. the coefficient on lag value of energy gap (- . *** and - . ***) are negative and statistically significant (table ). this implies that an increase in energy gaps (i.e., decrease in energy security) would de- crease the economic growth. the results indicate that rising energy demand and supply gaps halts the economic growth. the negative relationship between energy gaps and pakistan journal of applied economics economic growth could be a result of increasing energy demand or decrease in energy supply. therefore, it is important to know the remedies to narrow down the energy de- mand and supply gaps (i.e., raise energy security) for development in pakistan. therefore, the proposed objective of the study is to overcome the problem of en- ergy insecurity and make necessary policy recommendations. the government of pak- istan should focus on both the supply and demand management and theories on energy demand should be based on importance of energy efficiency. energy efficiency refers to the effective and efficient utilization of the available energy resources and if this is improved, it will produce the same amount of output by using less energy. this is one way to improve energy security by lowering energy demand. a study by ozturk ( ) also highlighted the importance of energy efficiency for energy security. this study mahmood and ayaz, energy security and economic growth in pakistan ols method on equation ( ) ols method on equation ( ) dependent variable:  ln yt dependent variable:  ln egapt lag length m = lag length m = variable coefficient variable coefficient c . *** c . [ . ] ( . ) [ . ] ( . )  ln yt- . ***  ln yt- - . [ . ] ( . ) [- . ] ( . )  ln yt- .  ln yt- - . [ . ] ( . ) [- . ] ( . )  ln egapt- - . *  ln egapt- . [- . ] ( . ) [ . ] ( . )  ln egapt- - . ***  ln egapt- . * [- . ] ( . ) [ . ] ( . ) r(- ) - . *** r(- ) - . [- . ] ( . ) [- . ] ( . ) no. of observations no of observations r . r . f-statistic (p-value) - . f-statistic (p-value) . d.w. statistic . d.w. statistic . table results for equations ( ) and ( ), (t= , – ) source:figure is based on authors’ calculations. notes: automatic selection of lags based on minimum aic: – . t- statistics in parenthesis [..] and probability or p-value in small brackets (...). ***, **, and * denotes rejection of null hypothesis at , and per cent level of significance, respectively. points that if government increase the energy efficiency, then it will not only save the exchequer but will also reduce the energy import dependency which will lead to boost the economy [qzturk ( )]. on the other hand, theories based on energy supply would give more importance to reliance on renewable energy resources for sustainable development. the government should use the alternative energy resources (i.e., solar energy, wind power and hydro power energy) to produce electricity in relatively cheap and efficient way. bibliography aqeel, a., and m.s. butt, , the relationship between energy consumption and economic growth in pakistan, asia-pacific development journal, ( ): - . asafu-adjaye, j., , the relationship between energy consumption, energy prices and economic growth: time series evidence from asian developing countries, en- ergy economics, ( ), - . awan, a.b., and z.a. khan, , recent progress in renewable energy – remedy of energy crisis in pakistan, renewable and sustainable energy reviews, : - . ayres, r.u., j.c. van den bergh, d. lindenberger and b. warr, , the underesti- mated contribution of energy to economic growth, structural change and eco- nomic dynamics, : - . bhattacharyya, s.c., , energy economics: concepts, issues, markets and gover- nance, new york: springer, london, doi . / - - - - . bielecki, j., , energy security: is the wolf at the door? the quarterly review of economics and finance, : - . chaudhry, i.s., n. safdar, and f. farooq, , energy consumption and economic growth: empirical evidence from pakistan, pakistan journal of social sciences, ( ): - . cherp, a., and j. jewell, , the concept of energy security: beyond the four as, energy policy, : - . chima, c.m., and r. freed, , empirical study of the relationship between energy consumption and gross domestic product in the u.s.a., international business and economics research journal, ( ): - . pakistan journal of applied economics ebohon, o.j., , energy, economic growth and causality in developing countries: a case study of tanzania and nigeria, energy policy, ( ): - . energy information administration-eia-international energy statistics, (n.d.), re- trieved from official energy statistics from the u.s. government. engle, r.f., and c.w. granger, , co-integration and error correction: represen- tation, estimation, and testing, econometrica, ( ): - . ghali, k.h., and e.m. sakka, , energy use and output growth in canada: a mul- tivariate cointegration analysis, energy economics, : - . iea, , energy statistics manual, international energy agency, paris http://www.iea.org/textbase/nppdf/free/ /statistics_manual.pdf, accessed on july . kakar, z.k., and b.a. khilji, , energy consumption and economic growth in pak- istan, journal of international academic research, ( ): - . kessides, n.i., , chaos in power: pakistan’s electricity crisis, energy policy, , - . kraft, j., and a. kraft, , on the relationship between energy and gnp, journal of energy and development, : - . khalil, h.b., and s.h. zaidi, , energy crisis and potential of solar energy in pak- istan: renewable and sustainable energy reviews, : – . khan, m.a., and u. ahmed, , energy demand in pakistan: a disaggregate analy- sis, the pakistan development review, : part-ii: – . lu, w., m. su, y. zhang, z. yang, b. chen, and g. liu, , assessment of energy security in china based on ecological network analysis: a perspective from the security of crude oil supply, energy policy, : - . malik, a., , power crisis in pakistan: a crisis in governance? pide monograph series, islamabad. morimoto, r., and c. hope, , the impact of electricity supply on economic growth in sri lanka, energy economics, : - . nakicenovic, n., p.v. gilli and r. kurz, , regional and global energy and energy efficiencies, energy, ( ): - . oztruk, i., , energy dependency and energy security: the role of energy efficiency and renewable energy sources, working paper, international growth center. pakistan, the pakistan economic survey, . pokrovski, v.n., , energy in the theory of production, energy, : - . saez, l., , u.s. policy and energy security in south asia: economic prospects and strategic implications, university of california press, ( ): - . shahbaz, m., and m. feridun, , electricity consumption and economic growth: empirical evidence from pakistan, quant, : . shaikh, f., q. ji, and y. fan, , the diagnosis of an electricity crisis and alternative energy development in pakistan: renewable and sustainable energy reviews, : - . mahmood and ayaz, energy security and economic growth in pakistan solow, r.m., , perspective on growth theory, the journal of economic perspec- tives, ( ): - . soytas, u., and r. sari, , energy consumption and gdp: causality relationship in g- countries and emerging markets, energy economics, : - . stern, d.i., , energy and economic growth in usa: a multivariate approach, en- ergy economics, - . stern, d. i., and c.j. cleveland, , energy and economic growth, rensselaer poly- technic institute, new york. stern, d.i., and k. enflo, , causality between energy and output in the long-run, energy economics, : - . valasai, d.g., m. uqail, h.r. memon and k. harijan, , overcoming electricity crisis in pakistan: a review of sustainable electricity options, renewable and sus- tainable energy reviews, : - . vlahinic-dizdarevic, n., and s. zikovic, , the role of energy in economic growth: the case of croatia, journal of economics and business, ( ): - . yu, e.s., and b.k. hwang, , the relationship between energy and gnp, energy economics, ( ): - . pakistan journal of applied economics electric power generating facilities. [paul j. stamler, washington university] many signs indicate that the united states is faced with an energy crisis. on the one hand, there is the historic growth trend of energy consumption, which has been doubling every to years. on the other hand, there is growing public concern with the en- vironmental and social consequences of producing that much energy and, fur- ther, of the social value of using it. public concern has been expressed in many communities regarding the con- struction of power plants and transmis- sion facilities; such concern promises to intensify in the future. there is an obvi- ous need for the relevant scientific data, and for public understanding of them. the symposium is intended to help meet this need. initially, one can either accept or reject the projection obtained by ex- tending the consumption patterns and trends of the past; this establishes the basis for defining energy "demand." when this demand is determined, one may then choose among the various means of energy conversion which are conventional at present or which are in some stage of development. this re- quires an evaluation, for each means of power generation, of the available fuel resources, the environmental im- pact, and the relation to relevant eco- nomic and social issues. however, all of these considerations are themselves influenced by assumptions regarding fu- ture demand for power, and these, too. must be reexamined. for example, by analyzing the various components that presently constitute energy demand, various alternatives can be devised to maximize social return per unit of en- ergy consumed. in turn, such alterna- tives may have important implications for the economic system, for social processes, and for life styles. the fore- november going considerations define issules to be examined in the symposium. the symposium is sponsored by the aaas committee on environmental alterations, which, in collaboration with the scientists' institute for public information, has been preparing a re- port on the subject. the symposium is made up of four sessions which will be held on and december. the gen- eral format provides for relatively short papers ( or minutes) each fol- lowed by questioning from the plat- form. following the formal papers, there will be approximately one hour of discussion between participants and audience. december nuclear power: expectations and implications participants: dean e. abrahamson, chairman (center for studies of the phys- ical environment, university of minne- sota); arthur tamplin (lawrence radia- tion laboratory); milton shaw (u.s. atomic energy commission, washington, d.c.); william hambleton (kansas state geological survey, university of kansas); theodore taylor (international research and technology corp., washington, d.c.); daniel ford (harvard university). milton shaw and arthur tamplin will review the entire nuclear program, emphasizing unresolved problem areas and the environmental and social im- plications of generating power through nuclear processes. theodore taylor will address the questions of safe- guards and physical security, and will discuss the storage of high-level radio- active wastes such as that proposed for salt mines in kansas. daniel ford, an active member of the union of con- cerned scientists, a group which has recently conducted an independent evaluation of possible reactor accidents, will discuss that aspect of nuclear power generation. william hambleton will talk on storage of high-level radio- active wastes. fossil fuels-today and tomorrow participants: arthur squires, chairman (the city college, new york city); jack o'leary (washington, d.c.); harry cau- dill (whitesburg, kentucky); hoyt hottel (m.i.t.); thomas stauffer (harvard uni- versity). jack o'leary will review the overall implications of a greatly expanded re- liance on fossil fuels, considering both today's technology and that which is anticipated for the decades ahead. hoyt hottel will consider coal gasification, harry caudill will discuss the social and environmental implications of min- ing-particularly surface mining in ap- palachia, and thomas stauffer will consider the strategic and financial im- plications of importing hydrocarbons. december technological alternatives participants: james fay, chairman (m.i.t.); c. john banwell and tsvi meidav (resources and transport divi- sion, united nations, new york city); r. baillie (university of west virginia); richard tybout (ohio state university). this session is to explore the present status and prospects for several tech- nological alternatives available as en- ergy sources or energy conversion means. each speaker will describe the energy source, give a status report on its present implications, and discuss the relevant research and development. john banwell and tsvi meidav will discuss geothermal energy, richard baillie will consider the fuel potential of trash and rubbish, richard tybout will review solar energy, and a fourth speaker will talk about controlled fusion. reducing the need for power participants: s. david freeman, chair- man (twentieth century fund, washing- ton, d.c.); barry commoner (washing- ton university); herman daly (louisiana state university); richard stein (archi- tect, new york city); john todd (new alchemy institute, woods hole, mass.). the final session is to explore various means through which substantial re- o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ ductions in power use might be effected or which could be implemented should a scarcity of power develop. barry commoner will consider the ecological importance and social implications of reducing reliance on power-intensive production technologies. john todd will discuss biotechnic decentralization as an alternative to the energy crisis; herman daly will consider the eco- nomic implications of a scarcity of en- ergy; and richard stein will review the implications of energy use and need from the standpoint of the architect. dean e. abrahamson university of minnesota medical school, minneapolis december geological implications of solid waste landfill * d; d~~~~~~~~ f x dfff'ff ffe d xf l i- x - -- (left). well-managed sanitary landfill opel ready for new development. trees were reta domestic and industrial solid wastes are being produced at an ever-increas- ing rate. every method for disposal of this by-product of our highly produc- tive society is encountering objections with the gradual awakening of an en- vironmental conscience in the public mind. with a concern for air pollution, incineration in major metropolitan areas is under attack; even incineration at its best leaves a residue which re- quires disposal. open dumping and burning, common methods for handling solid waste disposal, are under attack for health and esthetic reasons. in response to the recognized short- comings of other methods of solid waste disposal, the utilization of solid wastes for sanitary landfill has been the fastest growing technique in the (right). restored landfill area last decade. a landfill is a man-made geologic deposit with rather unique physical and chemical properties. its composition is strikingly inhomogene- ous, as is its particle size. the rate of compaction-settling is extremely high in comparison with natural geological sediments. the porosity and permeabil- ity of solid waste landfills vary within wide limits and the leachate which seeps forth is frequently a biological and chemical contaminant. the scheduled symposium on "geo- logical implications of solid waste landfill" is dedicated to the principle that "out of sight, out of mind" is no longer an acceptable basis for getting rid of solid wastes in the ground. geologists, hydrologists, planners, and landscape architects will address them- selves to the definition and recognition of the extent to which various geologic and hydrologic conditions in the ground favor or limit the selection of solid landfill waste disposal sites. there has also been developing a new expertise in the physical and chemical effects of the landfill waste materials upon thc sites themselves. the symposium will highlight many of the findings and parameters developed by leading re- searchers in this contemporary field. speakers and topics d. a. stephenson, what to do before the garbage truck a rrives. s. jackson hubbard, designt of a sanii- tary landfill. norbert b. schomaker, collstruction techniques for sanitary landfills. george m. hughes, hydrogeologic conz- trols on the movement of leaclhates from refuse. richard r. parizek and donald lang- muir, mantagement of leachates from sanzitary lazdfill. grover h. emrich, managemenzt of hazardous geologic conzditionis foor safe solid waste disposal. gary l. merritt and william c. buccia- relli, the geologic aspects in the plani- ning and implementtation of the penin- sylvania solid waste management act . edwin g. otton, solid waste disposal in the geohydrologic enviroiinment of marylanid. w. l. fisher and l. f. brown, jr., ge- ologic evaluation of santitary landfill sites, texas coastal zonie. arthur a. socolow state geologist and director, pennsylvania topographic and geological survey, harrisburg - december living systems: synthesis, assembly, origins several approaches to the artificial production of living systems will be re- viewed in this symposium. attention will be focused on systems and on the supporting levels of cellular construc- tion, especially the relevant macro- molecules. principal topics to be covered first are the chemical synthesis of contem- porary proteins (k. hofmann, uni- versity of pittsburgh) and nucleic acids (m. caruthers, m.i.t.). the assembly of such macromolecules into systems is emphasized through reports on ex- periments with polymers from living systems. many biomacromolecular preparations have been reassembled into organelles (d. j. kushner, univer- sity of ottawa); nuclei and cytoplasms of amoebas have been transferred from one membrane to another (j. f. danielli, state university of new york at buffalo); and models of primitive macromolecules (r. lohrmann and r. sanchez, salk institute; and d. l. rohlfing, university of south carolina) and of primordial cells and organelles (s. w. fox, university of miami) science, vol. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ - december the energy crisis: some implications and alternatives dean e. abrahamson doi: . /science. . . ( ), - . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the trademark of aaas. is a registeredscienceadvancement of science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for thescience © by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ hindawi publishing corporation journal of nanotechnology volume , article id , pages doi: . / / editorial nanomaterials for energy production and storage vaishali r. shinde, won bae kim, shrikrishna d. sartale, and tanaji p. gujar international center for young scientists (icys), national institute for materials science (nims), - - sengen, ibaraki, tsukuba - , japan advanced materials research laboratory, school of materials science and engineering, gwangju institute of science and technology, (gist), gwangju - , republic of korea department of physics, university of pune, pune , india department of physics and institute for functional nanomaterials, university of puerto rico, san juan, pr - , usa correspondence should be addressed to vaishali r. shinde, shinde vr @yahoo.com received december ; accepted december copyright © vaishali r. shinde et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. with the increasing world population and burst of portable electronic devices, automobile and other industries, the consumption of energy in many forms has been intensively escalated. however, the world energy sources are being consumed fast and this has put the world in a ditch of energy crisis. on the other hand, the availability of sustainable energy is crucial for the economic growth and industrialization, thus, sufficient and inexpensive energy is the most important demand of today. so this is the time to conserve the nonrenewable energy sources as well as to find the alternative sources of energy production and storage. in response to the needs of modern society and emerging ecological concerns, the new, low-cost, and environmentally friendly energy conversion and storage systems should be investigated, and research and development of this field should be rapidly accelerated. nanomaterials, with tailored characteristics at the nanometer scale, offer unique proper- ties or combinations of properties and will play a vital role in the development of new energy technologies for energy production and storage. in this special issue, we have selected out of received the relevant research articles and covered the broad field from worldwide scientists. in this issue we publish several research articles that are addressing these fields. s. sun et al. have introduced a carbon-free electrocatalyst based on pt/nb-tio for proton exchange membrane fuel cells (pemfc) applications, where a facile surfactant-free wet-chemical method was used to grow single-crystalline pt nanoparticles (np) on mesoporous nb-doped tio hollow spheres in aqueous solution. the use of nb-tio hollow spheres as substrate has been proved to provide a new type of cost-effective support with high corrosion resistance for pt- np. interestingly, the growth of pt-np on nb-tio support could be controlled by manipulating the mass ratios between the pt precursor and the nb-tio support. the pt-np/nb- tio catalysts have been demonstrated to enhance activity and stability compared with the commercial e-tek pt/c catalyst. i. k. basily et al. have presented a role of nanotechnology for the production of clean fuel e- and petrochemical raw materials. the aim of this experiment was to obtain unsaturated hydrocarbons from petroleum residues with the help of different types of nanocatalyst and to optimize the pyrolysis parameters of the two-stage reactor. the studies on the effectiveness of catalysts such as cao and gold nanocatalyst supported on cao for the yield and product distribution have been carried out. in this work it has been concluded that the au nanocatalyst with rods shape gives the maximum yield of ethylene (which can be converted easily to ethyl alcohols which is used as e- clean fuel) from petroleum residues. li-ion batteries are one of the efficient energy storage devices that have established a strong market position especially for portable electronic devices. in this context, t. matsuda and y. moritomo have demonstrated two-electron- reaction without structural phase transition in nanoporous cathode material. they have studied the charge/discharge properties, valence states, and structural properties of a nanoporous cathode material lixmn[fe(cn) ] . · . h o. thin film of lixmn[fe(cn) ] . · . h o was obtained by journal of nanotechnology substitution of na from na . mn[fe(cn) ] . · . h o which was synthesized electrochemically on an indium tin oxide (ito) transparent electrode. from the presented data it was clearly illustrated that the two-electron reaction without structural phase transition is responsible for the high charge capacity and the good cyclability observed in lixmn[fe(cn) ] . · . h o. j. y. z. chiou et al. have presented hydrogen production by reforming of ethanol over the ptrumg/zro catalyst. they have modified the ptru/zro catalyst with mg and studied the oxidative steam reforming of ethanol (osre) and the steam reforming of ethanol (sre) to realize the hydrogen production at a temperature lower than ◦c with higher ethanol conversion, hydrogen yield, and lower co distribution. the results show that the osre reaction requires a higher temperature (∼ ◦c) to achieve % ethanol conversion than the sre reaction (∼ ◦c). they have concluded that ptrumg/zro catalyst is suitable for sre reaction considering the catalytic stability against the coke deposition. carbon aerogels, the nanostructured porous materials with reasonable high surface area and electric conductiv- ity, are the potential candidate for electrochemical energy storage. a. peña et al. have presented synthesis of carbon aerogels by catalytic chemical vapor deposition method (ccvd) using ferrocene as a source both of catalytic material (fe) and of carbon. using the ccvd method they have obtained carbon aerogels with surface areas and pore volumes of m /g (sbet) and of . cm /g (vbjh), respectively. according to their analysis, the large surface area is due to mesopores formed by the aggregation of carbon nanostructures. these porous carbon aerogels present the promising features for applications in the physisorption of gases, for example, in the storage of molecular hydrogen for fuel cell applications. whilst storage of hydrogen is an important issue, the titanium decorated with organic compounds offers promis- ing features for high-capacity hydrogen storage. f. zuliani et al. have studied the adsorption of hydrogen molecules on a titanium atom supported by a benzene molecule using generalized gradient corrected density functional theory (dft) and elucidated the catalytic role of the ti atom in the dissociation of the h molecule. the authors have analyzed the orbital interactions responsible for the h binding to ti and for the dissociation of one h molecule. their results reveal that up to four h molecules can coordinate to the metal ion center, with adsorption patterns similar to those observed in ti-swnts and no more than one molecule dissociating in the process. with the detail studies and observation they have proposed ti on carbon supports as a new and efficient material for hydrogen storage. vaishali r. shinde won bae kim shrikrishna d. sartale tanaji p. gujar submit your manuscripts at http://www.hindawi.com scientifica hindawi publishing corporation http://www.hindawi.com volume corrosion international journal of hindawi publishing corporation http://www.hindawi.com volume polymer science international journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume ceramics journal of hindawi publishing corporation http://www.hindawi.com volume composites journal of nanoparticles journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume international journal of biomaterials hindawi publishing corporation http://www.hindawi.com volume nanoscience journal of textiles hindawi publishing corporation http://www.hindawi.com volume journal of nanotechnology hindawi publishing corporation http://www.hindawi.com volume journal of crystallography journal of hindawi publishing corporation http://www.hindawi.com volume the scientific world journal hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume coatings journal of advances in materials science and engineering hindawi publishing corporation http://www.hindawi.com volume smart materials research hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume metallurgy journal of hindawi publishing corporation http://www.hindawi.com volume biomed research international materials journal of hindawi publishing corporation http://www.hindawi.com volume n a n o m a te ri a ls hindawi publishing corporation http://www.hindawi.com volume journal of nanomaterials cal sciences, university of colorado at boulder (macon telegraph, macon, georgia); eric s. lander, mathematics department, princeton university (busi- ness week); arnold levinson, health, arts, and sciences program, university of california, berkeley (albuquerque journal, albuquerque, new mexico); brian h. magee, science and public pol- icy, university of washington (wgbh- fm, boston); barbara b. mandula, de- partment of biochemistry, brandeis uni- versity (san diego union); juan a. mejia, department of psychology, uni- versity of utah (ktvx-tv, salt lake city); robert h. millay, jr., department of biochemistry, university of texas, dallas (wfaa-tv, dallas); cathy l. reed, department of microbiology, her- shey medical center, pennsylvania state university (richmond times-dispatch, richmond, virginia); randi joy revitz, center for studies in criminology and criminal law, university of pennsylva- nia (wuhy-fm, philadelphia); randall j. strossen, department of psychology, stanford university (st. paul dispatch, st. paul, minnesota); gordon e. uno, department of botany, university of california, berkeley (koa-tv, den- ver); and mercedes lynn de uriarte, american studies program, yale uni- versity (los angeles times). interciencia association focuses on energy the interciencia association (ia) is providing a link in a "cooperative, inter- dependent approach to help resolve the hemisphere's energy crisis," according to alejandro orfila, secretary-general of the organization of american states (oas). orfila was addressing the national en- ergy forum on may in washington, d.c., when he applauded ia's attempts "through symposia and the journal inter- ciencia to bring science and technology more closely to bear on human needs and development." the interciencia association, founded by aaas and representatives of other scientific organizations in american na- tions, has held three symposia since its inception in , in keeping with its stated goal of advancing the appropriate use of technology and science for the benefit of peoples in the americas. a fourth meeting will be held in july this year on the subject of "marine sci- ence in the americas," in san jose, costa rica. a symposium currently in the planning stage is scheduled for mid-march in brazil. the focus will be on non- conventional energy resources and the relationships between energy supplies, development, and appropriate tech- nology. plans for the conference were first discussed at an interciencia work- shop at the denver annual meeting of aaas. attendees there expressed con- cern over the threat to development plans posed by increased costs of con- ventional energy sources, the question- able relevance of much conventional technology, and the need for cooperation on energy strategies and research. spokespersons for the ia have ex- pressed hope that, in addition to provid- ing an exchange of information on the state of the art in nonconventional ener- gy sources, the meeting will provide a useful input at the regional level for the united nations conference on science and technology, scheduled for . preliminary program plans for the interciencia symposium include such topics as major problems of latin ameri- ca which bear on needs for energy; as- sessment of major energy resource po- tentials of latin america with emphasis on which of these can be developed rap- idly; energy for rural peoples; impact of energy choices on urbanization and em- ployment; potential of biomass; and mechanisms for transfer of appropriate energy technologies. a broad range of institutions and indi- viduals are being encouraged to provide input to the symposium plans. aaas members and members of affiliated so- cieties are urged to contact the executive secretary, interciencia association, massachusetts avenue, nw, washing- ton, d.c. . james rowe director, western hemisphere cooperation project, office of international science coos sets priorities at june meeting energy and water resources on indian lands-the attrition rate of women in un- dergraduate and graduate science curric- ula-puerto rican representation among the science professions-minority repre- sentation among aaas committees- these were areas of high priority identi- fied by members of the aaas com- mittee on opportunities in science (coos) at its meeting and june in washington, d.c. the committee felt that aaas could take steps in two areas where energy re- sources and water on indian lands are concerned: first, inform the scientific and technological community as to the con- cerns of american indians in this area, such as exploitation of indian lands and the legal issues involved. second, aaas should work with indian organizations and communities to facilitate their identi- fication of needs for technology and hu- man resources. a question in which the committee expressed interest is the difference be- tween attrition rates of men and women in science curricula at both the under- graduate and graduate levels. identifying the reasons for the disparity in the drop- out rates of men and women may lead to more women completing their science education. the committee members reiterated their interest in pursuing funding for pro- jects that would seek to identify minority women professionals, especially below the ph.d. level. such a project could help in the establishment of regional meetings and result in local networks for communication among those already es- tablished in professions, as well as those still in school. members of coos felt a need for a regular newsletter that would report activities of other minority groups, policy developments in wash- ington, and funding possibilities. two puerto rican members of the committee, participating in their first meeting, called for help from aaas in identifying their human resources on the mainland. they urged the association to work with puerto rican organizations to gather data on both science professionals and graduate students, in order to better assess their needs. a discussion during the meeting of the controversial fellowship nomination of arthur jensen evolved into a discussion of the fellowship nomination procedure and the drafting of a request to the board of directors. in it, the committee de- cried the nomination as damaging to the credibility of the association, and rec- ommended revision of the fellows nomi- (continued on page ) science, vol. to order reports mentioned in aaas news or to request further information on our activities report- ed therein, please write to the appro- priate office at aaas, massa- chusetts avenue, nw, washington, d.c. , unless another address is given. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ interciencia association focuses on energy james rowe doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / . .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the is a registered trademark of aaas.sciencescience, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for the advancement ofscience by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / . .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ doi: . /j.bbabio. . . s abstracts / biochimica et biophysica acta ( ) s –s core metadata, citation and similar papers at core.ac.uk provided by elsevier - publisher connector however, under a range of pathological conditions no levels can rise to micromolar levels and disrupt a wide range of cellular processes. between these two extreme concentration ranges no can interact with mitochondria in ways that have been described as physiological or pathophysiological. the highest affinity target is cytochrome c oxidase. this talk will review this interaction and suggest that it has the potential to play a role in both no signalling and detoxification. no has also been shown to interact with lower affinity with mitochondrial cytochrome c in both its reduced and oxidised forms. previous studies have indicated that no can oxidise cytochrome c at physiological ph. we show that most of this oxidation is not caused by direct reactions of no, but instead by a reaction product of no and oxygen, most likely no . in contrast the reaction of no with oxidised cytochrome c is a direct, reversible binding. intriguingly in the presence of cardiolipin no can also bind reduced cytochrome c with high affinity at neutral ph. we will describe these interactions and comment on their biological relevance. doi: . /j.bbabio. . . s / mitochondria and reversible apoptosis guy c. brown department of biochemistry, university of cambridge, uk e-mail: gcb@mole.bio.cam.ac.uk apoptosis has been considered as a form of cell death, to which a cell is irreversibly committed once cytochrome c is released from the mitochondria. however, apoptosis can also be regarded as a means of signalling to phagocytes, which may in principle be reversible up to the point of phagocytosis. we find that mitochondrial cytochrome c release does not inevitably commit a cell to death because if the cell reduces the cytosolic cytochrome c then caspase activation is blocked. similarly caspase activation does not inevitably commit a cell to death, because the caspases can be inactivated by endogenous oxidants. phosphatidylserine flip to the outer leaflet of the plasma membrane is also a reversible process, as long as phagocytes are not present to eat the cell. we find that many aspects of apoptosis are fully reversible in neurons. this leads to the conclusion that apoptosis can (in some circumstances) be reversible and is not always a form of cell death. doi: . /j.bbabio. . . s / ischemic preconditioning invokes multiple mechanisms of nitric oxide and reactive oxygen signaling at the mitochondrial level paul s. brookes department of anesthesiology, university of rochester medical center, rochester, ny, usa e-mail: paul_brookes@urmc.rochester.edu ischemic preconditioning (ipc) is a phenomenon in which short cycles of ischemia and reperfusion (ir) can protect organs such as the heart and brain from prolonged ir injury. mounting evidence suggests that both mitochondria and nitric oxide play critical roles in ipc signaling, although the exact biochemical mechanisms underlying cardioprotection are poorly understood. we have identified novel biochemical events involving reactive oxygen and nitrogen species, which may contribute to the modulation of mitochondrial function in ipc: ( ) s-nitrosation and reversible inhibition of respiratory chain complex i. ( ) activation of mild uncoupling via the generation of no derived electrophilic lipids (nitro-alkenes) and their post-transla- tional modification of mitochondrial carrier family proteins. ( ) endogenous generation of mitochondrial k+atp channel agonists and complex ii inhibitors, via redox reactions involving krebs' cycle intermediates. together, it is thought that these pathways all act to diminish mitochondrial ca + overload and ros generation at reperfu- sion, thereby limiting the opening of the permeability transition pore. a brief outline of the key findings in support of these novel signaling pathways will be discussed. doi: . /j.bbabio. . . (s ) mitochondria and reactive oxygen containing species symposium abstracts (poster and raised abstracts) s . mild uncoupling reduces oxidative stress in intact cells alexander m. wolf, sadamitsu asoh, ikuroh ohsawa, shigeo ohta department of biochemistry and cell biology, institute of development and aging sciences, graduate school of medicine, nippon medical school, japan e-mail: awolf@nms.ac.jp “mild uncoupling”, the introduction of a limited proton conduc- tance into the mitochondrial inner membrane, has been demonstrated to greatly reduce reactive oxygen species (ros) production in isolated mitochondria. on the other hand, it will also increase energy consumption to maintain the mitochondrial membrane potential, and cells need energy in the form of nadh to maintain the cellular protein machinery in the normal, reduced state. for this reason it has been a subject to debate whether mild uncoupling is a viable strategy to reduce oxidative stress in intact cells and ultimately in vivo, or whether the increased energy expenditure might have detrimental effects. using a redox-sensitive green fluorescent protein (rogfp ) targeted to mitochondria of pc cells, we found that mild uncoupling using low concentrations of chemical uncouplers fccp or dnp indeed reduced oxidative stress, whereas strong uncoupling caused oxidation of rogfp , indicating that the beneficial effects of uncoupling are limited to a certain range of membrane potential, and that uncoupling beyond this range will increase oxidative stress probably due to energy crisis. this leads to the conclusion that while mild uncoupling might be beneficial under some circumstances, it is a dangerous strategy since the safe range of uncoupling will probably depend on cell type and metabolic state. doi: . /j.bbabio. . . s . the role of reactive oxygen and nitrogen species in the pathogenesis of acute renal failure egor plotnikova, anastasia chupyrkinaa, alena vasilevaa, aleksandr kazachenkob, vladimir kirpatovskyb, dmitry zorova aa.n. belozersky institute, moscow state university, moscow, russia bresearch institute of urology, moscow, russia e-mail: plotnikov@genebee.msu.ru the aim of this work was to study mechanisms of acute renal failure (arf) development in kidney survived ischemia or mioglobi- nuria (rabdomyolysis). experimental model of those pathologies showed that days after ischemia or induction of rabdomyolysis, the levels of urea, creatinine and cell death markers increase. such kidney malfunctioning can be caused by tubular epithelium destruc- tion. in our experiments, lipid peroxidation products accumulated in kidney and total antioxidant activity of blood are decreased. also the level of nitrite in blood serum was increased indicating the activation of no production. analysis of ros- and no-production in kidney cells revealed amplification of the production of these radicals. we https://core.ac.uk/display/ ?utm_source=pdf&utm_medium=banner&utm_campaign=pdf-decoration-v http://dx.doi.org/doi: . /j.bbabio. . . http://dx.doi.org/doi: . /j.bbabio. . . http://dx.doi.org/doi: . /j.bbabio. . . http://dx.doi.org/doi: . /j.bbabio. . . mailto:gcb@mole.bio.cam.ac.uk mailto:paul_brookes@urmc.rochester.edu mailto:awolf@nms.ac.jp mailto:plotnikov@genebee.msu.ru available online http://ccforum.com/content/ / / page of (page number not for citation purposes) abstract studies with negative results rarely hit the headlines. but the results are often just as important as the positive ones. a number of ‘negative headline’ studies are looked at in this review: intensive insulin therapy regime, thrombolysis in cardiac arrest, the effects of nutritional guidelines and rapid response outreach teams. intensive insulin therapy the debate about intensive insulin therapy continues to be fought, with a recent paper from saudi arabia by arabi and colleagues [ ]. in , a landmark paper by van de berghe and colleagues [ ] showed that an intensive insulin regime resulted in a significantly lowered mortality in a surgical intensive care unit (icu) compared to standard insulin therapy. as intensive insulin therapy is a relatively simple intervention with a promising survival benefit, it is no wonder it was widely adopted by icus around the world. however, a more cautious attitude has recently been adopted following the negative results of a follow-up study by van de berghe in the medical icu [ ] and the results from the visep study [ ] suggesting harm from tight glycaemic control. in arabi’s mixed medical and surgical icu single-centred study, patients were randomly allocated to either inten- sive insulin therapy (aiming to keep glucose levels between . and . mmol/l) or conventional insulin therapy (between . and . mmol/l). the primary end point of icu mortality was used. a plethora of secondary end points were assessed, including rates of hypoglycaemia. results showed there was no statistical difference in icu mortality between the two groups ( . % versus . %). there was also no difference in any of the secondary end points except hypoglycaemia, which occurred more fre- quently in the intensive insulin therapy arm. based on these results, the authors stated that they ‘do not advocate universal application of intensive insulin therapy to icu patients’. the study was powered for an absolute reduction of % based on extrapolating the results from van de berghe and colleagues’ study [ ], which showed an absolute mortality reduction of . %. therefore, it may be criticised that this was an underpowered study; the trend was to a reduction in mortality - a non-significant absolute risk reduction of . %. to look for a small absolute reduction of mortality a large trial is needed. currently, such a randomized, multicentered trial is being conducted. aptly named nice-sugar [ ], it com- pleted the last of the recruitment in november and results are now awaited. more evidence that tight glucose control may not be beneficial for all patients came from a paper by oddo and colleagues [ ]. they performed a retrospective analysis of data from patients with severe brain injury. as part of an observational study, these patients received intensive insulin therapy to try and keep their systemic glucose levels between . and . mmol/l. brain tissue markers of glucose metabolism were obtained by a frontal lobe microdialysis catheter. cerebral glucose levels were measured as were lactate and pyruvate levels. a brain energy crisis was defined as a cerebral microdialysis glucose of < . mmol/l with a lactate/pyruvate ratio > . systemic blood samples were categorised as low sugar (< . mmol/l), tight ( . to . mmol/l), intermediate ( . to . mmol/l) and high (> mmol/l). compared to inter- mediate control, tight glycaemia control was associated with a greater prevalence of low cerebral microdialysis glucose levels and more brain energy crises. the number of brain energy crises was also associated with an increased risk of hospital death. commentary recently published papers: a series of negative results robert galloway and richard venn department of critical care, worthing hospital, worthing, west sussex, bn dh, uk corresponding author: robert galloway, drrobgalloway@gmail.com published: february critical care , : (doi: . /cc ) this article is online at http://ccforum.com/content/ / / © biomed central ltd icu = intensive care unit. critical care vol no galloway and venn page of (page number not for citation purposes) although this is only a small study - it too leaves us with difficult questions. it is well accepted that hyperglycaemia should be controlled after head injury - but clearly we need to be careful because tight control may cause harm. cardiac arrest management meanwhile, the search for improvement in survival from out of hospital cardiac arrest continues. approximately % of patients with cardiac arrest have underlying acute myocardial infarction or pulmonary embolism. therefore, there could be a role for routine use of thrombolysis during cpr. a pan-european study [ ] investigated this. patients who had a presumed cardiac related cardiac arrest were randomised in the pre-hospital setting to either tenecteplase or placebo. if the patient was in asystole or pea (pulseless electrical activity), the drug was given immediately. if in a shockable rhythm, then it was given after the third shock if there had been no return of spontaneous circulation. the primary end point was day survival. unfortunately, the results showed no improvement in survival or in any of the secondary outcomes. although this study shows that there is no evidence for routine use of thrombolysis in cardiac arrest, the authors make it clear that the results do not suggest that thrombolysis should be withheld in patients in whom the primary pathological condition is known to be responsive. indeed, patients who were presumed to have a pulmonary embolus were excluded from the randomisation and given tenecteplase. nutrition on icu there is evidence that providing early nutritional support to icu patients reduces mortality. however, this is not universally followed. doig and colleagues [ ] presented a clustered randomised controlled trial across icus in australia and new zealand to see if evidence-based feeding guidelines could be implemented and reduce mortality. half the participating icus carried on their normal feeding policy whilst the other half implemented evidence-based guidelines with specific measures aimed at improving compliance with the guidelines. a practice-change strategy of specific interventions was devised. individual hospitals used various aspects of this strategy. the results of the study show that although guideline icus fed patients earlier and achieved calorific goals more often, there was no significant difference in mortality, icu length of stay or hospital length of stay. this surprising and somewhat disappointing result needs explanation. it could be that original research from which the guidelines were taken either overestimated the benefit of early feeding or was not transferable to this patient setting. other explanations may be that compliance with the guidelines was not % or the ‘hawthorne’ effect of the control group. knowing that they were being studied may have led to improvements in their nutrition management regard- less of guidelines. but the important take home message is that implementing nutrition clinical care guidelines improves feeding regimes. rapid response teams although it seems rational to have outreach teams that respond to a set of deranged physiological parameters, few studies have showed evidence for their benefit and others show no benefit [ ]. another negative trial is from kansas, missouri [ ]. a prospective cohort study looked at over , adult inpatients admitted for months before and after a rapid response team was introduced. the general trends in the first months (that is, the decreasing number of cardiac arrest calls) were taken into consideration in the statistical analysis. although there was a reduction in the number of out of icu cardiac arrests, this did not translate into a significant difference in hospital mortality. it may be that introducing a rapid response team allows a more dignified death in those whose resuscitation is futile and, therefore, reduces the number of cardiac arrest calls without improving mortality. on the other hand, mortality may not have been affected because the interventions were ineffective. this needs further study. competing interests the authors declare that they have no competing interests. references . arabi ym, dabbagh oc, tamim hm, al-shimemeri aa, memish za, haddad sh, syed sj, giridhar hr, rishu ah, al-daker mo, kahoul sh, britts rj, sakkijha mh: intensive versus conven- tional insulin therapy: a randomized controlled trial in medical and surgical critically ill patients. crit care med , : - . . van den berghe g, wouters p, weekers f, verwaest c, bruyn- inckx f, schetz m, vlasselaers d, ferdinande p, lauwers p, bouil- lon r: intensive insulin therapy in the critically ill patients. n engl j med , : - . . van den berghe g, wilmer a, hermans g, meersseman w, wouters pj, milants i, van wijngaerden e, bobbaers h, bouillon r: intensive insulin therapy in the medical icu. n engl j med , : - . . brunkhorst fm, engel c, bloos f, meier-hellmann a, ragaller m, weiler n, moerer o, gruendling m, oppert m, grond s, olthoff d, jaschinski u, john s, rossaint r, welte t, schaefer m, kern p, kuhnt e, kiehntopf m, hartog c, natanson c, loeffler m, reinhart k; german competence network sepsis (sepnet): intensive insulin therapy and pentastarch resuscitation in severe sepsis. n engl j med , : - . normoglycaemia in intensive care evaluation and survival using glucose algorithm regulation (nice - sugar study) [http://clinicaltrials.gov/ct/gui/show/nct ] . oddo m, schmidt jm, carrera e, badjatia n, connolly es, pre- sciutti m, ostapkovich nd, levine jm, le roux p, mayer sa: impact of tight glycemic control on cerebral glucose metabo- lism after severe brain injury: a microdialysis study. crit care med , : - . böttiger bw, arntz hr, chamberlain da, bluhmki e, belmans a, danays t, carli pa, adgey ja, bode c, wenzel v; troica trial investigators; european resuscitation council study group: thrombolysis during resuscitation for out of hospital cardiac arrest. n engl j med , : - . . doig gs, simpson f, finfer s, delaney a, davies ar, mitchell i, dobb g; nutrition guidelines investigators of the anzics clinical trials group: effect of evidence-based feeding guidelines on mortality of critically ill adults: a cluster randomized controlled trial. jama , : - . . hillman k, chen j, cretikos m, bellomo r, brown d, doig g, finfer s, flabouris a; merit study investigators: introduction of the medical emergency team (met) system; a cluster ran- domised controlled trial. lancet , : - . erratum in lancet , : . . chan ps, khalid a, longmore ls, berg ra, kosiborod m, spertus ja, hospital-wide code rates and mortality before and after implementation of a rapid response team. jama , : - . available online http://ccforum.com/content/ / / page of (page number not for citation purposes) 	abstract 	intensive insulin therapy 	cardiac arrest management 	nutrition on icu 	rapid response teams 	competing interests 	references international journal of management sciences and business research, sep- issn ( - ) vol- , issue international journal of management sciences and business research, sep- issn ( - ) vol- , issue http://www.ijmsbr.com page “impact of energy crisis on the financial performance of textile sector, listed on karachi stock exchange” “a time series analysis ( - )” author’s details: ( ) faheem-ul-hussain dehraj-m.phil scholar, department of business, administration shah abdul latif university, khairpur-pakistan ( ) dr. muhammad saleh memon-associate professor, department of business, administration shah abdul latif university, khairpur-pakistan ( ) abdul naveed tariq, ph. d-school of international business and management ( ) zaheer abbas awan-(lecturer business administration) shaheed benazir bhutto university, shaheed benazirabad abstract: energy serves an important role in the financial performance of textile industry. this research ascertains the relationship between electricity consumption and financial performance of textile industry of pakistan after energy crisis, based on the sample data taken for the period of - . electricity consumption is taken as independent variable and roa, roe and npm as considered the dependent variables. data was analyzed through descriptive statistics and regression tests. descriptive statistics confirms the declining trend in the financial performance ratios while regression test shows significant positive strength of relationship among dependent and independent variables. this study identifies how important electricity consumption is for the financial performance of textile industry therefore government of pakistan should focus on utilization of alternative energy resources and shift from oil usage to hydro energy which has higher resources available which in turn will smooth the way for financial performance and economic growth key words: energy consumption, roa, roe, nmp, financial performance . introduction/background energy consumption is the sum of energy remaining for ultimate consumption after deducting power wasted in conversion and supplying through main power distributors, the variation in energy spending distress heavily the level of large scale production development that in return influence the expansion of actual gdp. each day human needs are presented in anxiety intended for goods and services because the manufacturing process directly associated with energy resources since that energy has got important attention by the researchers as the world has become completely globalized (survey, - ). the amount of energy spending in the economic growth has been recognized from the reality that the extra production declined during the ( ) throughout the globe that was mainly reason of oil disaster. earlier the nineteen seventy, the success of nation and long term economy relied over the basic element of production such as investment, human resource and land but since the longer period, the energy was given no place and importance among these factors of production by the economist and overlooked its significance from the production process (pakistan economic survey, - ). different factors affecting performance ratios of textile sector such as from shortage of electricity, increasing interest rate, prices of oil, gas, lack of new technology and political instability. much amount of money is required to generate the electricity privately is another issue by the rising interest in pakistan while the industry spends less time due to the absence of electricity therefore output level of this sector is get affected at the higher cost of production (hafiz, ). pakistan’s economic and consistent growth potential ineradicably connected to energy requirements because there is increasing demand in pakistan from different sources of energy. due to an increasing economy and the need for huge manufacturing and consumption throughout the country is evident due to foreign direct investment and rising population. government has been working hard to meet this energy shortage and international journal of management sciences and business research, sep- issn ( - ) vol- , issue http://www.ijmsbr.com page encouraging the renewable sources and efficiency. pakistan can get remedies through different projects by exploring every possibility through exploiting its renewable sources and further expected this need will increase in near future (pakistan economic survey, - ). pakistan needs of electricity energy was about , to , mw each day during against having generation capacity around , megawatt by the day, this shows the gap of approximately “ to mw” during each day and its requirement was likely to raise about , mw each day during (haq, ). this scarcity is severely hitting commerce, industry, everyday life and getting risks to the economic growth. while pakistan fulfills its seventy five percent of power needs from native resources together with “gas, oil and hydroelectricity’ generation but just twenty five percent energy requirements managed through imports with oil takes large proportion alone (sahir, ). for the past years statistics show, the gap has times increased since - to - between the requirement of commercial energy demand and supply as of milion tons mtoe to milon mtoe. according to the daily report of wapda on rd january, documented a distribution of “ , megawatt” beside need of , megawatt of electricity, showing the shortage of about thirty seven percent and recorded the shortfall around , mw (asif, ). pakistan ranked in asian countries the th biggest international seller of cloth goods. textile sector contributes about % in the employment of the country and this sector largely reliant on the sp inning activity in pakistan. currently this textile industry of pakistan is operating the “ spinning units, large sinning units and , ginning unit” for the manufacturing of textile goods in this state (ahmed y. , ) table economic contribution of pakistan textile industry (m.a & a.s & m.r, ) figure growth trend of textile industry (m.a & a.s & m.r, ) international journal of management sciences and business research, sep- issn ( - ) vol- , issue http://www.ijmsbr.com page this is the trend survey for last decade ( to ) shows how growth is changeable each year. since from , it was gradually increases and showing a jump from % to % in - growth, due to higher input prices and record of high export and got a seventh largest market in us cotton. in year - the growth rate was at its peak, as exports had improved and foreign investors were confident to invest and a consistence down trend is shown after this peak since (economic survey of pakistan, - ). . . pakistan energy sources:  natural gas  coal  oil  electricity . . alternative energy sources  wind  solar  nuclear energy the main objective of this research is to investigate the extent of energy crisis impact on the post -financial performance of textile sector in pakistan during the period ( - ), listed on karachi stock exchange (kse). the impact of energy crisis on financial performance is the burning and most frequent discussed issue among economist and politicians in pakistan. . literature review the energy short fall and other concerned issues have created the resistance of economic development harshly in pakistan owing to ineffective, immature and disappointingly developed infrastructure. no serious attention is given by the government of pakistan to enhance the production capability of electricity generation for helping economic prosperity rapidly for the decades (ahmed & dessouky, ). as a result, when energy requirement is larger than the distribution, the government decides to load management by load-shedding and rising price approaches. according the government of pakistan, to curtail the energy crisis issue, the cpec is the ideal project in the country. this project will attract $ -$ billion foreign direct investment by the chine’s firm to the independent power production (ipp) as of investment policy. further minister planning develo pment and reforms ahsan iqbal remarked the cpec project would cover main four areas and energy is one of top priority which will bring about , megawatts as by the end of (kiani, ). khurshid & anwar,( ) reported in his research taking post energy crises from to that operating and financial performance was declined by the major different sectors of cement, textile and engineering mean while the other industries of chemical and sugar remained consistent and recommended that to keep the industries safe the government of pakistan must pay attention on power sector. khan & k.m, ( ) investigated in his research the multifarious issues are faced by this major sector of textile including rising cost of input, declining in foreign trade and much caused of energy crises these together have decreased the growth of the sector. textile sector is an only largest manufacturing industry in the pakistan which adds major share in economic growth in term of foreign exchange, foreign trade, investment, earning and employment. it has been studied in various findings that electricity have major role in the survival of industrial prosperity and growth which includes the main reforms in process of production, fully exploitation of workforce, managerial expertise and technology according to the ministry of finance (khan & k.m, ). khan & k.m, ( ) investigated in his research the multifarious issues are faced by this major sector of textile including rising cost of input, declining in foreign trade and much caused of energy crises these together have decreased the growth of the sector. siddiqui r. ( ) reported in his survey research the link between economic growth and impact of electricity and petroleum product and finally suggested high significance among these, this mean in pakistan, more access international journal of management sciences and business research, sep- issn ( - ) vol- , issue http://www.ijmsbr.com page in energy consumption would add to the economic wellbeing and vice versa when decrease in consumption will cause hurdle in growth. further by another researcher applying horizontal analysis for textile sector by using main ratios and concluded the performance of this sector is harshly declined after energy crisis comparing to pre energy crisis period (shah, essrani, shah, & rehmat, ). dr quratul ain, ( ) investigated thatpakistan can resolve its power crisis and stand together with modern world, if only our states man would agree to accept transparent policies, efficient laws, stay away from corrupt practices and search and spend in alternate and renewable resources of energy. according to the world top research journals the industrial and service sectors performances like pakistan international airlines, steel mills and pakistan railways are suffering from unexpected losses due to shortfall of oil and gas which brought down gdp growth about percent during fy and fy . the world is now devising renewable energy and better transport infrastructure policies to get rid from poverty, to get engaged the millions of workers by enlarging industries and encouraging foreign investment to enabling economies. . proposed research model: independent variable dependent variable . research hypothesis: h . more energy consumption will lead to increase in roa of textile industry. h . increase in energy consumption will increase the roe of textile industry. h .npm of textile industry will increase only because of increasing in energy consumption. . methodology: the number of firms in textile sector varies the high and a low in and respectively (ali, ). but for this study firstly we take into the consideration of whole textile sector by using the overall industrial ratio from the consolidated financial statements from the state bank of pakistan about those firms together which didbusiness successfully for sample period - which without being closed. secondly the industrial commercial electricity consumption data was used from the statistical year book by the pakistan bureau of statistics. . statistical analysis: for data analysis spss was used, data was analyzed through descriptive statistics and regression test to ensure the relationship among all the dependent and independent variables. . results & discussion: . . descriptive statistics analysis table : . industrial electricity consumption (bajwa, ) international journal of management sciences and business research, sep- issn ( - ) vol- , issue http://www.ijmsbr.com page figure the electricity consumption in pakistan have been increasing every year as shown in above graph, due to increasing population and foreign direct investment. further it is said that most of people from rural areas are shifting to urban areas (urbanization), who then consume energy in their homes along with increasing manufacturing and exports activities of textile industry needs maximum energy consumption in the country. table: return on assets figure financial statements analysis of (non-financial) companies by (sbp, - ) the graph above shows the roa . % of the textile sector at the time of energy crisis period in , however a striking decline happened during at - . % and in to - . % converted completely profit into losses. while stabilizing by and , this rising and declining trend assures the affected profitability of textile industry largely by the energy crisis. table : return on equity financial statements analysis of (non-financial) companies by (sbp, - ) figure international journal of management sciences and business research, sep- issn ( - ) vol- , issue http://www.ijmsbr.com page during the period of energy crisis, the roe of textile sector was . % but at time of it declined at - . % and - . % respectively occurred during but could be stabilizing by at . % and . % in . this up and down trend of roe shows the roe of the sector has been affected by the energy crisis. table: net profit margin financial statements analysis of (non-financial) companies by (sbp, - ). figure the npm (net profit on sales) before the energy crisis was . % in fy and . % in (beenish shah, may ),during the crisis period in it was . % however this trend is shown in cyclical pattern in above graph and finally converted into losses in the year (- . %). the industry started stabilizing in the year at . % and . % the profit during . this declining and rising trend of npm shows that the profitability decreased in the post crisis period and confirms the impact of energy crises on the sector. this is because of increasing cost of generating electricity privately through generators and due to high interest rate on browed capital, being used for manufacturing activities which ultimately affects the net profit margins. . . regression analysis simple regression analysis model: international journal of management sciences and business research, sep- issn ( - ) vol- , issue http://www.ijmsbr.com page table: in the model first the adjusted r is . at the significance level . this shows that our model of both independent variable “electricity consumption” along with dependent variable “roa” is good fit at . %, at confident interval of . %. whereas the standardized beta is . this suggests the moderate positive strength of relationship between electricity consumption and roa and these results are significant at both p value (. ) and t value ( . ). according to the statisticians the minimum standard of p value is . , means there is only a % chances of error term to accept the results and t value must be significant at . % so that our first hypothesis is accepted. simple regression analysis model: table: in the second model the adjusted r is . at the significance level . this tells that our model of both independent variable “electricity consumption” along with dependent variable “roe” is good fit at . %, at confident interval of . %. whereas the standardized beta is . this shoes the high positive strength relationship between electricity consumption and roa because the beta is near to one and these results are significant at both p value (. ) and t value ( . ). based on this information second hypothesis is also accepted. simple regression analysis model: table: international journal of management sciences and business research, sep- issn ( - ) vol- , issue http://www.ijmsbr.com page in the third model the adjusted r is . at the significance level . this shows that our model of both independent variable “electricity consumption” along with dependent variable “nmp” is good fit at . %, at confident interval of . %. whereas the standardized beta is . this shoes the moderate positive strength of relationship between electricity consumption and these results are significant at the both p value (. ) and t value ( . ). based on this information the third hypothesis is also accepted. . conclusion for the longer pakistan is confronting with worst crisis of energy and there is a constantly increasing gap between energy demand and supply. this energy scarcity is badly affecting the manufacturing activities of different industries and thus declining the growth of economy. textile industry not only is contributing gdp growth but major portion of our export as well. this study uses regression tests and concludes how financial growth is related with electricity usage. regression analysis shows the significant positive strength of relationship among electricity consumption and roa, roe & npm which also confirms an increase in electricity consumption will smooth the way for roa, roe and nmp. . recommendation and future research direction some remedies include; to control the electricity theft and transmition and distribution loss along with shift from oil usage to hydro energy which has higher resources available and it is estimated that pakistan can generate about mw electricity by implementing different hydro projects, government should also give attention towards the use of wind and solar energy which can help to fulfill some energy deficit, and e nergy through nuclear resources and coal reserves can also be increased. further this study can be put forwarded while looking at the impact of taxes and interest rate on the performance of textile industry of pakistan. . limitations this research study is limited for time and area of research. findings of this study can only be applied in problematic situations of textile sector and can be generalized to the other sub-division of economy and enables policy makers of this industry managing other affordable alternative sources of energy through wind, solar and from coal at the time of energy crisis. bibliography i. ahmed, k. &., & dessouky, h. ( ). prospect of biodiesel in pakistan. renewable and sustainable energy reviews, vol nos and , pp. - . ii. ahmed, y. ( ). textile industry of pakistan, s,l: harizon securities ( smc-pvt) ltd. iii. ali, i. ( ). determinants of capital structure:empirical evidence from pakistan. university of twente enchede the netherlands . iv. asif, m. ( ). energy crisis in pakistan origins challanges and sustainable solution,karachi. oxford university press . v. bajwa, a. ( ). statistical year book. pakistan bureau of statistics government of pakistan . vi. dr quratul ain, m. ( ). economic cost of energy crisis in pakistan and the way forward. retrived www.thealpapers.com . vii. economic survey of pakistan. ( - ). finance division government of pakistan, islamabad . viii. hafiz, m. y. ( ). impact of electricity and interest rate on textile industry of pakistan. punjab group of colleges, daska, pakistan (vols. volume , issue ). academy of contemporary research journal. international journal of management sciences and business research, sep- issn ( - ) vol- , issue http://www.ijmsbr.com page ix. haq, n. ( ). "energy crises in pakistan" in n-ul haq and k. hussain (eds). x. khan, a., & k.m, a. &. ( ). pakistan textile industry facing new challanges. research journal of international studies (issue ), pp. - . xi. khurshid, m., & anwar, w. ( ). energy crisis and performance of industry of pakistan: an empiricial study of kse listed companies. international journal of african and asian studies-an open access international journal, vol , - . xii. kiani, k. ( , april ). chines president due today on historic visit. the dawn . xiii. m.a, & a.s & m.r, k. ( ). quaility related issues and their effects on return of pakistan textile industry. journal of quaility and technology management, volume x ((isssue )), - . xiv. pakistan economic survey. ( - ). energy, chapter , - . xv. pakistan economic survey. ( - ). chapter no , page - . xvi. sahir, m. &. ( ). "spacific concerns of pakistan in the context of energy security issues and geopolitics of the region". energy policy, vol. , - . xvii. sbp. ( - ). financial statements analysis of companies ( non-financial) by sbp, listed on karachi stock stock exchange. xviii. shah, b., essrani, s., shah, n., & rehmat, n. ( ). impact of of energy crises on the textile sector. journal of emerging issues in economics, finance and banking, volume: no. , - . xix. siddiqui, r. ( ). energy and economic growth in pakistan. the pakistan development review, : , - . xx. survey. ( - ). pakistan economic survey, islamabad ministry of finance. intellectual property and biofuels: the energy crisis, food security, and climate change queensland university of technology from the selectedworks of matthew rimmer may , intellectual property and biofuels: the energy crisis, food security, and climate change matthew rimmer, australian national university college of law griffith hack available at: https://works.bepress.com/matthew_rimmer/ / http://www.qut.edu.au/ https://works.bepress.com/matthew_rimmer/ https://works.bepress.com/matthew_rimmer/ / intellectual property and biofuels: the energy crisis, food security, and climate change matthew rimmer, mike lloyd, george mokdsi, doris spielthenner, and ewan driver* abstract in light of larger public policy debates over intellectual property and climate change, this article considers patent practice, law, and policy in respect of biofuels. this debate has significant implications for public policy discussions in respect of energy independence, food security, and climate change. the first section of the paper provides a network analysis of patents in respect of biofuels across the three generations. it provides empirical research in respect of patent subject matter, ownership, and strategy in respect of biofuels. the second section provides a case study of significant patent litigation over biofuels. there is an examination of the biofuels patent litigation between the danish company novozymes, and danisco and dupont. the third section examines flexibilities in respect of patent law and clean technologies in the context of the case study of biofuels. in particular, it explores the debate over substantive doctrinal matters in respect of biofuels – such as patentable subject matter, technology transfer, patent pools, compulsory licensing, and disclosure requirements. the conclusion explores the relevance of the debate over patent law and biofuels to the larger public policy discussions over energy independence, food security, and climate change. keywords: patent law, biofuels, energy, food security, water security, biodiversity, agriculture, biotechnology, clean technologies, renewable energy, climate change. * dr matthew rimmer (ba/llb anu, phd unsw) is a professor of intellectual property and innovation law at the queensland university of technology (qut), brisbane, australia. this research was supported an australian research council future fellowship on intellectual property and climate change. mike lloyd, george mokdsi, and ewan driver are all members of the griffith hack group, and doris spielthenner is from ambercite. this group conducted the network patent analysis in the first section of the paper. the authors acknowledge alison mclennan for her conversations on synthetic biology and biofuels. introduction biofuels have a long and rich pre-history. at the world’s fair in , rudolf diesel – the inventor and patent holder - and the otto car company exhibited a diesel engine, which ran on peanut oil (tomes, lakshmanan, and songstad , ). recognising the value of food crops for fuel, diesel observed that “power can... be produced from the heat of the sun, which is always available for agricultural purposes, even when all natural stores of solid and liquid fuels are exhausted” (goodall , ). similarly, the car manufacturer, henry ford, observed in : “the fuel of the future is going to come from fruit like that sumach [a type of tree] out by the road, or from apples, weeds, sawdust – almost anything” (goodall , ). he rhapsodized: “there is fuel in every bit of vegetable matter that can be fermented.” (goodall , ). in his leading work, biofuels and the globalization of risk, james smith provides a definition and classification of modern “biofuels”: biofuel refers to energy derived from biomass through processes such as combustion, gasification or fermentation. these processes yield energy in the form of liquid or gas fuels. a range of biological sources can act as feedstock for these processes, including dedicated energy crops (such as grasses and trees), traditional crops (sugar cane and oilseed) as well as crop residues and degradable waste (for example, wheat straw, rice hulls, and organic waste). the resulting fuel can be used in cooking, heating, electricity generation and transport (smith , ). biofuels are defined in terms of various generations. smith thus observed that first-generation biofuels “rely on food crops that boast readily accessible sugars, starches and oils as their feedstock” (smith , ). he noted: “the most common feedstocks are sugar cane… sugar beet, maize, wheat and other starchy cereals, such as barley, sorghum and rye” (smith , ). smith defined second-generation biofuels as those which “rely on bio-chemical and thermochemical conversion” (smith , ). second-generation biofuels rely on feedstocks – such as “perennial grasses such as switchgrass, trees such as poplar or willow and residues and wastes derived from agricultural production” (smith , ). moreover, smith noted that “third-generation biofuels focus on improving the feedstock” (smith , ). the third generation of biofuels has used algae, microalgae, and seaweed. there has been a discussion of whether there exists a fourth generation of biofuels focused upon biotechnology. james smith observed: “even more theoretically, fourth-generation technologies hypothetically offer entirely custom-made feedstocks and microbes to process fuel” (smith , ). there has been much public and private investment in the various generations of biofuels. james smith observed: “over the last decade, increasing awareness of the impacts of climate change and dwindling supplies of fossil fuels can be seen to have generated investment in fields such as biofuels, climate-ready crops and storage of agricultural genetic resources”. in the united states, president barack obama has emphasized that biofuels are part of his energy independence policy: “biofuels are an important part of reducing america’s dependence on foreign oil and creating jobs here at home” (the white house ). there has also been much interest in the use of biofuels in canada (de beer ), and south american countries, such as brazil (la rovere, pereira, and simões ). in the garnaut review , ross garnaut argued that “australia has an important role to play in research and development on biofuels” (garnaut , ). in , the gillard government established the $ million australian biofuels research institute (ferguson ). the institute's work is designed to provide “support for the potential of next-generation biofuels to increase australia's energy security and diversify sources of liquid fuel supply” (ferguson ). in the european union, the european commission has established a directive to promote the use of biofuels and other renewable fuels for transportation (european commission ). there has also been interest in biofuels in africa (matondi, havnevik, and beyene ; juma ). the roundtable on sustainable biomaterials has sought to develop a global standard and certification scheme for the sustainable production of biomass and biofuels. achim steiner, executive director of the united nations environment programme, observed in : “biofuels are neither a panacea nor a pariah but like all technologies they represent both opportunities and challenges” (united nations environment programme ). the nuffield council on bioethics reflected that biofuels have become part of a larger policy debate over the energy crisis, food security, biodiversity, and climate change. the council observed that the hope was that biofuels would provide “a new source of income for farmers and revenue from ‘clean’ technology, as well as renewable – and therefore endless – sources of fuel, leading to far less greenhouse gas (ghg) emissions than fossil fuels” (nuffield council on bioethics , xvii). the council noted that investment in biofuels had been encouraged by “increasing worries over energy security in the face of growing demand, dwindling supplies of oil, and international conflicts and wars” (nuffield council on bioethics , xvii). moreover, “the growing awareness of the dangers of global climate change reinforced the challenge to find alternatives to fossil fuels as the dominant form of energy” (nuffield council on bioethics , xvii). critics, though, have questioned whether biofuels should be classified as ‘renewable energy’ or ‘sustainable’. tony seba ( ) from stanford university contends that biofuels are obsolete and uncompetitive in comparison to solar energy and wind power. he also argues that biofuels are water intensive and damaging to food security. seba is also critical of government subsidies http://www.amazon.com/s/ref=ntt_athr_dp_sr_ ?_encoding=utf &field-author=kjell% havnevik&search-alias=books&sort=relevancerank http://www.amazon.com/s/ref=ntt_athr_dp_sr_ ?_encoding=utf &field-author=atakilte% beyene&search-alias=books&sort=relevancerank of biofuels: “the only thing that’s renewable about the agricultural biofuels industry is the special-interest lobby groups that represents it in places like washington, brazilia, and brussels” (seba, : ). this article considers the various legal and political debates over patent law and biofuels, and the concomitant implications for energy independence, food security, and climate change. smith has observed that biofuels are the subject of much debate: ‘biofuels fire the imagination of policy-makers, entrepreneurs, researchers and governments because of the possibility of being all things to all people’ (smith , ). he warns that biofuels also risk becoming ‘objects of contestation, or ideas around which ideologies and politics are fought, much as agricultural biotechnologies were before them’ (smith , ). the first section provides a network analysis of patents in respect of biofuels across the three generations. in particular, it highlights fundamental subject matter, clusters of biofuels, and influential patents. it also focuses upon the fragmented and diverse ownership in the field of patent law and biofuels. the second section looks at patent litigation over biofuels. as a case study, it considers the ongoing conflict between the danish company novozymes, and danisco and dupont in respect of biofuel patents. the third section examines patent law, policy, and practice in respect of clean technologies – focusing upon biofuels. in particular, it explores the debate over substantive doctrinal matters in respect of biofuels – such as patentable subject matter, technology transfer, patent pools, compulsory licensing, and disclosure requirements. the conclusion explores the relevance of the debate over intellectual property and biofuels to the larger public policy discussions over energy independence, food security, biodiversity, and climate change. a network analysis of biofuels in september , the united nations environment programme, the european patent office, and the international centre for trade and sustainable development published a landmark report on patents and clean energy (karachalios et al. ). the study emphasized: “despite the importance attached to the role of intellectual property rights in the transfer of climate change technologies to developing countries, it is only recently that empirical research has begun to appear on the issue” (karachalios et al. , ). the study stressed that “the absence of an evidence-based approach has fed into the rhetoric and stalemate in the climate change negotiations” (karachalios et al. , ). the report noted: “in order to move away from the abstract to an evidence-based approach, there is an urgent need for greater empirical analysis” (karachalios et al. , ). the study concluded: “in terms of building on the empirical data gathered thus far and to move the debate forward, there is a need for additional research” (karachalios et al. , ). in this context, this chapter seeks to make an original contribution to the literature on patent law and clean technologies by providing a network analysis of biofuel patents – across three generations. a literature review of patent landscapes there have been a number of previous studies – often sector-specific and country-specific – which have sought to provide patent landscapes in respect of clean technologies. in a sophisticated discussion of methodological strengths and weaknesses, e. richard gold and andrew baker from mcgill university review the use of patent landscaping as a means of understanding and analysing technology development, innovation policy and business strategy (gold and baker ). the pair commented that “patent landscaping is a method of understanding the interrelationship of data extracted from patent documents across a certain dimension, be that technological, geographical, or company” (gold and baker , ). gold and baker observed: “while a potentially powerful tool, patent landscaping has, to date, been conducted largely on an ad hoc basis” (gold and baker , ). the canadian researchers comment that two common problems in patent landscaping are the failure to disclose justifications for methodological choices, and drawing conclusions from analytical methods that do not meet the norms for evidence-based policy making. gold and baker comment that “patent landscaping has come of age with the availability of large patent databases and the increasing sophistication of search and analytical tools” (gold and baker, , ). the scholars made a number of suggestions as to how to harmonise and standardise the use of patent landscaping methodologies in the future. in , professor john barton offered an analysis of patent law and biofuel technologies (barton ). he commented: “patent issues are likely to arise primarily with the newer technologies, because the older ones are long off-patent, and there is enormous patenting activity in the new areas” (barton , – ). barton observed: “there also appears to be a technology race in the use of algae as a source for fuel” (barton , – ). he also commented that “patents are likely to apply to the technologies developed under government support, as will the licensing restrictions associated with us government-sponsored technology” (barton , – ). john lazarus, patent expert for foley lardner, has conducted annual surveys of patents in respect of clean technologies (lazarus ; lazarus ; lazarus ). one of his sub- categories of clean technologies is for the collective group of biomass, biogas and biofuel. in , john lazarus observed of biofuels: “the biomass/biogas/biofuel energy field in accounted for approximately six percent of patents in the cleantech landscape, which is a slight decrease from ” (lazarus ). he suggested: “the biomass/biogas/biofuel technology area having the greatest potential white space under this indicator is ‘system/process for making a biofuel’” (lazarus ). lazarus commented: “the biomass/biogas/biofuel technology area for which patent protection was most actively obtained in both (based upon number of claims granted) is ‘ethanol production from biomaterial,’ which was closely followed by ‘system/process for making a biofuel’” (lazarus ). he observed: “individual inventors accounted for approximately percent of the biomass/biogas/biofuel patents, indicating a fairly significant scope of new biomass/biogas/biofuel developments that may be available for access by licensing or acquisition” (lazarus ). he also commented: “u.s. entities obtained approximately percent of the biomass/biogas/biofuel patents, with a majority of those patents going to entities in the midwest” (lazarus ). lazarus commented that, given the statistics on examination of biofuel patents, “it may be advantageous to seek accelerated examination of particularly promising new biomass/biogas/biofuel technology developments” (lazarus ). a number of jurisdictions around the world have introduced fast-track mechanisms in respect of the examination of clean technologies. san diego patent attorney, eric lane, has argued that there should be an international system established to facilitate fast-track examination of patent applications for clean technologies (lane a). he envisages that the establishment of a “global green patent highway would be a powerful mechanism for fostering green innovation and should be employed as a tool in the battle to combat climate change” (lane a, ). in , michael ward, and timothy hall, lawyers at morrison and foerster, observed that “the biofuel patent landscape is increasingly crowded and fragmented” (ward and hall ). the pair noted: “a recent patent study found that there are at least biofuel patents and pending applications in the united states, europe, and japan, divided among companies, with only companies owning more than five patents” (ward and hall ). ward and hall concluded that the patent thickets for biofuels raised issues in respect of the freedom to operate: “in such a congested intellectual property environment, freedom-to-operate issues become crucial to any entity in the space” (ward and hall ). the trilateral study by the united nations environment programme, the european patent office, and the international centre for trade and sustainable development provides a broad overview of patent law and clean technologies (karachalios et al. ). the study provides some useful information about patents in respect of biofuels. in a summary of its larger study of intellectual property and climate change, the third world network charted the patent field in respect of biofuels (shashikant and khor , ): over the last six years, a total of , biofuel-related patents were published in the us, with the number increasing by over % in each of the past two years. analysis of biofuel-related patents published in to revealed the following breakdown of patents: biodiesel ( ), agricultural biotechnology ( ), ethanol and other alcohols ( ), enzymes ( ) and biomass ( ). further broken down by ownership entity, the patents published in the selected technologies in to were % owned by corporate entities, % owned by universities or other academic institutions and % undesignated (i.e., the patent applications do not list the patent owner). worldwide, the highest number of biofuel patents in to originated from the us ( ), germany ( ), japan ( ), italy ( ), and france ( ). the study suggested that “as venture funding and government funding increase, the number of biofuel patents will continue to grow steadily” (shashikant and khor , ). the report maintained: “future legislation directed towards climate change is also expected to strongly influence biofuel patents” (shashikant and khor , ). sandra thompson has also undertaken a number of patent studies of biofuels for industrial biotechnology (thompson a; thompson b; thompson c). network patent analysis a network patent analysis is a patent analysis process, which uses citation connections between patents to both group and rank patents. a network patent analysis can be deployed to analyse citation connections in order to determine the most important patent groupings and patents. ambercite and griffith hack comment that a “network patent analysis” consists of “a set of analytical and visualisation tools that use citation links to both group patents of similar technologies and rank patents” (lloyd, spielthenner, and mokdsi ). they maintain that “[l]arge numbers of patents can be analysed to ensure statistical reliability, with up to , patents and one million citation linkages being analysed in some studies” (lloyd, spielthenner, and mokdsi ). the technique of network patent analysis has been previously deployed in a number of contexts. the tool has been applied to the contested field of the smartphone patent wars (lloyd, spielthenner, and mokdsi ), and has been used in the medical field to provide an overview of the leading patents, research and applicants in respect of patenting trends for the treatment of alzheimer’s disease (lloyd, mokdsi, and spielthenner ). in the field of patent law and clean technologies, network patent analysis has been a powerful tool to understand the conflicts over hybrid car technologies (lloyd and blows ) – in particular, the dispute between paice and toyota (lloyd and spielthenner ). in this study, the team sought to apply the methodologies and analytical tools of network patent analysis to the topic of biofuels. first, the research team conducted an initial traditional patent search, such as a keyword of international patent classification code search. this produced a set of , starting patents. second, the research team added to the dataset all patents which were connected by citation to the starting patents, and were not already within the list of starting patents. there were , additional patents found through this method. this led to a total of , patents in the combined dataset. third, the researchers applied network patent analysis to this dataset and obtained , central highly connected patents. fourth, the researchers prepared network diagrams based on these central patents. fifth, the researchers categorised the patent records according to the generation of biofuels using keyword and international patent classification criteria.i the research team also cleaned up the assignee names using manual and automated techniques. there are a number of methodological limitations to the patent landscape and the network analysis. first, the search of the collections took place on june th, . the results of the search are dependent upon the records available at the time the search was conducted. second, the applications are generally only published months after they are first filed and it may take some additional time for applications to be reviewed and indexed for availability via the various collections. third, there may be errors or omissions in the databases which prevent the location of potentially relevant records. finally, the searches could only identify records indexed to an international patent classification mark, or related to other search criteria. network patent analysis: generations there has been much debate about the incidence of patent applications in technological fields. there has been much discussion about the issue of “patent thickets”. carl shapiro famously described a “patent thicket” as a “dense web of overlapping intellectual property rights that a company must hack its way through in order to commercialise new technology” (shapiro , ). patent offices have been grappling with the phenomenon (european patent office ). the nuffield council on bioethics commented: “given the range of technologies likely to be involved in the production of new biofuels, the area seems particularly prone to patent-stacking and patent-thickets” (nuffield council on bioethics , ). michael heller has used the term “the tragedy of the anticommons” to discuss the situation where multiple, overlapping patent rights block access to patented inventions (heller and eisenberg ; heller ; heller ). david lametti has questioned whether the language about the “tragedy of the anticommons” is helpful or useful in describing patent landscapes or networks (lametti ). some commentators have also sought to develop language to describe situations where is an absence of patents. john lazarus refers to “white spaces” where there are fields of technology with little or no patent applications (lazarus ; lazarus ; lazarus ). the patent landscape and the network patent analysis conducted in this study highlights that the field of biofuels is crowded with patents. the initial patent landscape review identified , patents in this area. the majority of the patents were filed after the year , with an acceleration in patent filings after , building up to a peak in . however this growth was not evenly split between the three generations of biofuels. keywords were used to try to assign the different patents to the three generations, and this was used to classify almost , of the , patents by generation. this can be seen in table . table – outcomes of classification of biofuels into different generations row labels count of patent number st generation , nd generation , rd generation other , total , clearly, when separated into generations, the first generation of biofuels is the most well represented in terms of patent filings. the patent register is crowded and cluttered in this sector. the second generation of biofuels is also represented by a significant number of patent filings. patent filings relating to the third generation of biofuels are still only lightly represented. it is worth noting that there were a number of biofuels patents ( , ) which did not fit into the generation-based classifications. biotechnology-based biofuels would also appear to be under- represented thus far in patent filings and could be an area of significant future patenting activity. in his book, a blueprint for a safer planet, lord nicholas stern from the united kingdom has argued that research and development should be focused upon later generations of biofuels, given the impact of the first-generation of biofuels upon food security and greenhouse emissions (stern , – ). the environmental leader and former united states vice president, al gore, has observed: “the second generation for producing ethanol - when it becomes commercially available - has a significant advantage over the first generation technology: instead of using food crops, it will make liquid fuels from perennial grasses, fast- growing trees, and waste streams with a high cellulose content” (gore , ; see also gore ). moreover, there is a third-generation of biofuels being developed by enterprising biotechnology companies. gore reflected that “the main focus of the third generation is end products that are superior to ethanol, including new molecules (like biobutanol) that can be mixed directly with gasoline and diesel, eliminating blending problems” as well as “the production of transportation fuel from algae” (gore , ). network patent analysis: clusters the patents connected by citation to the original data set, but not in the original data set, led to a total of just over , patents. the patents were clustered using the network patent analysis process (represented in figure ). the network patent analysis identified the most highly connected , patents, the vast majority which fell into clusters, along with broker patents (where there was no strong allegiance to any of the clusters). table/ figure . biofuels network patent analysis the biofuels patents can be further broken into sub-categories. as can be seen in figure , the clusters can be grouped into three main areas: biodiesel (table ); biogas (table ); and cellulosic biofuels and by-products (table ). table – clusters found in the biodiesel grouping of clusters row labels (number of patents in cluster) cluster name leading patent title and owner of leading patent owner of strongest patent portfolio within cluster (% of cluster value) a ( ) esterification ( ) us ( ) process for production of esters for use as a diesel fuel substitute using a non- alkaline catalyst, agricultural utilization research institute, us uop, owned honeywell, us, ( %) d ( ) biofuels from algae ( ) us ( ) methods of and systems for producing biofuels, haliae, us haliae, us, ( %) f ( ) biodiesel purification ( ) us ( ) methods of purifying biodiesel fuels, scott powell, us, scott powell, us, ( %) g ( ) chlorohydrin production ( ) us ( ) process for the manufacture of dichloropropanol by chlorination of glycerol, solvay, belgium solvay, belgium, ( %) l ( ) hydrodynamic cavitation of biodiesel ( ) us ( ) apparatus and method for producing biodiesel from fatty acid feedstock, arisdyne systems inc, us five star technologies, us, ( %) o ( ) production of algae ( ) us ( ) microorganism growth apparatus, university of ben gurion, israel algae systems, us, ( %) q ( ) beta-carotene as a fuel additive ( ) us ( ) liquid fuel mixture, method for is production, and its use for two stoke engines, schure and werner, germany oryxe energy international, inc, us, ( %) s ( ) biodiesel as a fuel additives ( ) ep ( ) fuel additives, exxon mobil, us exxon mobil, us, ( %) t ( ) centrifugal separation of fluids ( ) us ( ) microwave assisted centrifuge and related methods, battelle energy alliance, us battelle energy alliance, us, ( %) table – clusters found in the biogas grouping of clusters row labels (number of patents in cluster) cluster name leading patent title and owner of leading patent owner of strongest patent portfolio within cluster (% of cluster value) b ( ) bioenergy from liquid waste ( ) us ( ) systems for prevention of hap emissions and for efficient drying/dehydration processes, earthrenew, us earthrenew, us, ( %) e ( ) electrolytic treatment of effluent ( ) us ( ) electrolytic cell and method of use thereof, mcalister technologies, us mcalister technologies, us, ( %) i ( ) enzymes for biofuel cells ( ) us ( ) enzyme immobilization for use in biofuel cells and sensors, university of st louis, us university of st louis, us, ( %) j ( ) gas treatment ( ) us ( ) method and system for a condensing boiler and flue gas cleaning by cooling and liquefaction, fawzy abdelmalek, us sustainc, us, ( %) k ( ) fuel injectors for biofuels ( ) us ( ) fuel injector actuator assemblies and associated methods of use and manufacture, mcalister technologies, us mcalister technologies, us, ( %) m ( ) sequestration of co ( ) us ( ) co -sequestering formed building materials, calera corp, us calera corp, us, ( %) n ( ) hydrogen purification ( ) us ( ) hydrogen producing fuel processing system, idatech llc, us idatech llc, us, ( %) r ( ) production of syngas from biomass ( ) us ( ) hydrogasification of biomass to produce high yields of methane, donald scott, canada university of california, us, ( %) table – clusters found in the biogas grouping of clusters row labels (number of patents in cluster) cluster name leading patent title and owner of leading patent owner of strongest patent portfolio within cluster (% of cluster value) c ( ) bio-ethanol from fibrous waste ( ) us ( ) fibrous materials and composites, xyleco, us xyleco, us, ( %) h ( ) making precipitated cellulose ( ) us ( ) process for making precipitated cellulose, akzona, us weyerhaeuser, us, ( %) p ( ) solid fuel from biomass ( ) us ( ) suspension firing of hog fuel, other biomass or peat, weyerhaeuser, us weyerhaeuser, us, ( %) there were also broker patents, which are patents not exclusively associated with any single cluster (see table ). table – broker patents z ( ) broker patents ( ) us ( ) methods for producing polyols using crude glycerin, university of ohio, us concocophillips, us ( %) network patent analysis: ownership the patent landscape and network patent analysis highlights a diversity of ownership in respect of patents and biofuels (table ). there is no single dominant company, or even leading group of companies. the leading owner, roy mcalister and mcalister technologies of the united states, held patents. the belgian company solvay held patents, and the university of california held patents. table – leading owners of biofuels owner number of patents in , biofuel patent search mcalister technologies/roy mcalister (us) solvay (belgium) university of california (us) university of tsinghua (china) bekon energy technologies (germany) sunho biodiesel (taiwan) uts umwelt (germany) chevron (us) ube industries (japan) upm kymmene (finland) there is a mixture of private and public ownership. in terms of private companies, there is a mixture of energy companies, agricultural companies and biotechnology companies making filings in respect of biofuels patents. there is also evidence that fossil fuel companies such as chevron have been moving into the field of alternative fuels, such as biofuels. the united states government and united states universities are well-represented in the patent filings. this is to be expected given the investment by united states governments in respect of biofuels. network patent analysis: priority countries and filing countries in terms of the patent landscape, the national affiliations of the patent applications are striking. there is still a great diversity in terms of priority countries and filing countries for biofuels patents (see tables and ). the united states, china, members of the european union, japan and south korea figure prominently in the statistics. table . biofuel patents: priority country age band - row labels count position united states china germany japan world intellectual property office korea (south) european patent office france great britain brazil table . biofuel patents: filing country age band - row labels count position united states china world intellectual property office germany european patent office japan korea canada india brazil there has been much competition and rivalry between the united states and china in respect of clean technologies. in his state of the union address in , president barack obama commented: “as long as countries like china keep going all in on clean energy, so must we” (obama b). the field of biofuels is worth considering in this respect. the study undertaken identifies the leading priority countries for identified biofuel patents from to . the united states leads until – when it is overtaken by china, and relegated to second position. china has consistently risen in terms of its patent filings – from third in to second in and first in . germany slips in its position from second in to third place for the following years. this trend is perhaps reflective of larger developments in respect of patent filings. in , the world intellectual property organization reported that china led the way generally in patent applications in (world intellectual property organization ; saez ). the world intellectual property organization found that china had , patent applications, followed by the united states with , applications, and , for japan. litigation over patent law and biofuels while there may be a diversity of patent ownership in respect of biofuels, the field has not necessarily been a harmonious and peaceful area. there has been significant patent litigation in respect of biofuels, despite some predictions to the contrary by commentators such as john barton (barton ). eric lane has commented: “though we are seeing new innovations nearly every day in second-and third-generation biofuels such as cellulosic ethanol and algae- based biodiesel, it is the first-generation biofuel technology that is scalable and widely commercialized” (lane , ). he commented: “accordingly, companies that have developed and implemented technology for processing first-generation biofuels are starting to enforce their patents” (lane , ). there have been a number of prominent disputes in respect of patent law and biofuels. such disputes have raised questions of validity, patent infringement and patent remedies. litigation between novozymes and danisco the danish company, novozymes, is the holder of a large patent portfolio – including in the area of biofuels: “biofuels are currently the only realistic option proven to successfully accomplish large-scale co emission reductions while creating jobs, boosting economic growth, and improving energy security” (novozymes ). novozymes is the patent holder of united states patent no. , , , which is entitled alpha amylase mutants with altered properties (thisted et al. ). the patent application reads: “the variants of the invention are suitable for starch conversion, ethanol production, laundry wash, dish wash, hard surface cleaning, textile desizing, and/or sweetener production.” in , the company sued danisco, along with genencor international wisconsin, for patent infringement of united states patent no. , , (novozymes a/s v danisco a/s a). formed in from an industrial merger, danisco is a danish company which focuses upon food production, industrial enzymes, and other bioproducts. danisco was acquired by e.i. dupont de nemours & co (“danisco”) in . in response to novozymes’ infringement complaint, danisco questioned the validity of the patent – particularly in terms of whether it provided sufficient written description of the claims (novozymes a/s v danisco a/s b). danisco also denied that there had been any patent infringement. the company also raised equitable defences under the doctrines of prosecution laches and prosecution history estoppel. novozymes v danisco: the ruling on patent infringement in , district court judge barbara crabb noted that the parties were competitors in the production and sale of enzymes called alpha-amylases used in making ethanol and other products (novozymes a/s v danisco a/s a). focusing upon the question of written description, crabb j. was unconvinced by danisco's attack on the validity of the patent: “although i still have doubts that the specification in the ' patent provides an adequate written description for the claims, i conclude that defendants have not met their burden to prove by clear and convincing evidence that the ' patent is invalid as a matter of law” (id. at p. ). http://www.danisco.com/wps/wcm/connect/www/corporate the judge came to the reluctant conclusion: “it is not without hesitation that i am denying defendants' motion” (id. at p. ). she worried: “plaintiffs do not contradict defendants' observation that, if plaintiffs' position is accepted, it means that plaintiffs disclosed . x possible inventions in their specifications” (id.). she concluded nonetheless that “a reasonable jury could conclude that the written description is adequate under facts in similar cases” (id. at p. ). the judge wondered whether the problem was really a question of enablement, rather than one of written description. at the next stage of the proceedings, the judge considered questions of patent infringement, and allegations of inequitable conduct relating to inventorship and prosecution laches. the judge held that “[t]here is no dispute that the accused products meet the remaining limitations of the asserted claims” (novozymes a/s v danisco a/s b at p. ). the judge ruled: “accordingly, i conclude that plaintiffs are entitled to summary judgment on the issue of infringement with respect to all of the accused products with the exception of the "whole broth" products, which do not meet the ‘isolated variant’ limitation” (id.). novozymes v danisco: patent remedies on october , the jury in the united states district court for the western district of wisconsin awarded damages to novozymes for patent infringement (novozymes a/s v danisco a/s c). the jury held that novozymes had lost $ , , usd on its sales of liquozyme products as a result of danisco’s infringement of the patent. furthermore, the jury ruled that novozymes lost $ , , usd on its sales of glucoamylase as a result of danisco’s infringement of the patent. moreover, the jury held that $ , , usd would constitute a reasonable royalty to novozymes for other lost sales resulting from danisco’s infringement of united states patent no. , , . the jury also found that novozymes had proven by clear and convincing evidence that danisco’s infringement of the patent was willful. however, the jury did not find that novozymes had proven infringement of danisco’s whole broth products. so, in total, the jury awarded novozymes $ . million usd in the danisco trial over enzymes (chopping, ; and decker and sulugiuc, ). the decision highlighted a longstanding debate of whether it is appropriate for juries to play such a significant role in patent disputes in the united states (rimmer ; miller ; duffy and lemley ) and raised questions about the appropriateness and proportionality of remedies in patent matters. novozymes v danisco: ruling on patent validity on may , barbara crabb of the united states district court for the western district of wisconsin ruled against novozymes in respect of the validity of the patent (novozymes a/s v danisco a/s ). she commented that “the parties in this case have debated tenaciously many issues of infringement, invalidity and damages, but the focal point has always been the adequacy of the written description for the ‘ patent” (id. at p. ). crabb j. reflected: “since the beginning of the case, i have questioned the validity of the patent in this respect . . . having reviewed the evidence at trial, the developing case law on this issue and the parties’ arguments in their post-verdict motions, i am persuaded that defendants have proven by clear and convincing evidence that the claims of the ‘ patent are invalid as a matter of law” (id. at pp. – ). accordingly, crabb j. vacated the judgment and instructed the clerk of court to enter judgment in the favour of the defendants, danisco. novozymes v danisco: united states court of appeals for the federal circuit novozymes appealed against the decision to the united states court of appeals for the federal circuit (novozymes ). novozymes’ general counsel mikkel viltoft observed: “we disagree with the decision and will file an appeal to the united states court of appeals for the federal circuit . . . novozymes will continue to protect and defend its intellectual property rights” (id.). oral argument was heard in the dispute in novozymes a/s. v dupont nutrition biosciences on february (novozymes a/s. v dupont nutrition biosciences ). the judges were the experienced combination of rader cj, schall and bryson jj. for the majority, schall j held that the patent claims were invalid because of the failure to meet the written description requirement. in its analysis, the judge held “that no reasonable jury could find that the claims of the ' patent meet the written description requirement of § , ¶ , and that the district court therefore correctly entered judgment as a matter of law invalidating those claims (novozymes a/s. v dupont nutrition biosciences : ).” the judge held: “in our view, this case is very analogous to university of rochester, where the patent specification failed to disclose any compounds that could be used in the claimed methods, which required administering a drug having a certain selective activity (inhibiting pghs– activity in a human host).” (novozymes a/s. v dupont nutrition biosciences : ). the judge concluded: “in sum, we agree with the district court that no reasonable jury could conclude that the application provides adequate written description to support the later-filed claims of the ' patent” (novozymes a/s. v dupont nutrition biosciences : ). rader cj dissented: ‘in conclusion, the jury received expert testimony, heard from skilled protein engineers, reviewed visual aids and publication excerpts, and examined the patent document as guided by those skilled in the art, over an eight day trial’ (novozymes a/s. v dupont nutrition biosciences : ). the judge argued: ‘the jury was given a special verdict form asking whether dupont had proven by clear and convincing evidence that the claims at issue were invalid for lack of written description’ (novozymes a/s. v dupont nutrition biosciences : ). his honour maintained ‘the jury answered in favor of novozymes, and substantial evidence supports this determination’. rader cj concluded: ‘therefore, i would reverse the grant of judgment as a matter of law and reinstate the jury's verdict’ (novozymes a/s. v dupont nutrition biosciences : ). dupont biofuel solutions ( ) was delighted by the victory over novozymes. soonhee jang, vice president, ip strategy and chief ip counsel, dupont industrial biosciences, said that “the court of appeals recognized our rights in the marketplace as a true innovator providing customers with choices.” a rehearing en banc by the united states court of appeals for the federal circuit was denied in october . other litigation there is other biofuels-related patent litigation involving danisco and novozymes across a number of jurisdictions. there have been other actions on foot in the united states. in august , danisco sought a declaration in the northern district of iowa and the northern district of california that the company’s rapid-starch alpha-amalyse products did not infringe a novozyme patent, and that the patent is invalid, in any case (danisco us inc. v novozymes a/s). the court dismissed the case in , holding that there was no justiciable controversy between the parties because novozymes had not engaged in any affirmative acts to enforce its patent rights against danisco (lane ). in the united states, novozymes also sued illinois enzyme distributor, cte global, for patent infringement. the parties settled the lawsuit in , and the court entered a consent judgment and a permanent injunction ending the lawsuit (lane b). such infringement proceedings are not limited to the united states. in the european union, there has been complex patent litigation between novozymes and danisco in relation to patents on animal feed (bausch and eitle ). there has also been significant patent litigation between novozymes a/s and danisco a/s over inventions relating to foodstuffs in the full court of the federal court of australia in (novozymes a/s. v danisco a/s. ). there has been conflict in the australian patent office in between novozymes a/s and genencor (novozymes a/s v genencor international, inc.). novozymes a/s has also opposed patent applications by north carolina state university and bioresource international in the australian patent office (novozymes a/s v north carolina state university and bioresource international, inc.). there have been other significant skirmishes in respect of patent law and biofuels. there has been a significant patent war between the advanced biofuels company gevo and the bp- dupoint joint venture, butamax advanced biofuels (butamax advanced biofuels llc and e.i. dupont de nemours and co. v gevo inc. ; see also lane b). there have been at least patents at issue in this conflict. the biofuels patent war continued in (lane, ). in the case of neste oil, oyj v dynamic fuel llc., neste oil has complained in the united states district court for the district of delaware of direct and induced patent infringement of a united states patent relating to a “process for the manufacture of diesel range hydrocarbons” (neste oil, oyj v dynamic fuel, llc). in , the court stayed the biodiesel lawsuits, pending the re-examination of the asserted patents (lane, ). there have also been a number of disputes in respect of trade secrets.ii in , novozymes filed a lawsuit in the united states district court for the eastern district of missouri, accusing boli bioproducts, a missouri company, of infringing u.s. patent no. , , (novozymes a/s v boli bioproducts usa llc; lane, ). in the future, there may well be further conflict over patents in respect of first generation biofuels. such litigation may lead to consolidation of market ownership and dominance in respect of biofuels. it can be anticipated that there will be litigation in respect of the second and third generations of biofuels, as technologies in those sectors mature and grow in influence. in addition to patent law, a number of other species of intellectual property can be deployed to address biofuels. trade secrets, plant breeders’ rights (rimmer a), and trade-marks can also be invoked to provide intellectual property protection in relation to biofuels. the question of eco-labelling deserves further consideration. the roundtable on sustainable biomaterials has been focused on the use of trade marks to certify the environmental impact of biofuels. such labelling could help differentiate between sustainable biofuels, and those which have an adverse impact upon land and water, food security, biodiversity, or climate change. the policy debate over intellectual property and biofuels http://www.bolibio.com/ in his book, a practical guide to working with trips, antony taubman identifies a number of positions to patent law reform in the field of clean technologies and climate change (taubman ). taubman observed that “amidst a dynamic debate over trips and climate change, three general sets of proposals can be identified” (taubman , ). one position is to “keep the status quo, but implement it more effectively, such as through improved flow of information about patented technologies and licensing opportunities” (taubman , ). a second position is to “adopt initiatives akin to the access to medicines process, establish specific measures to remove barriers to using trips flexibilities, on the model of trips bis” (taubman , ). a third position is to “implement more fundamental changes to rules on patents, such as revocation or refusal of patents on technologies needed for climate change adaptation or mitigation, and specific carve-outs for least developed countries and other countries vulnerable to climate change impacts” (taubman , ). taubman comments that “these proposals reflect divergent philosophies and working assumptions about the interplay between the ip system and efforts to promote innovation and diffusion of green technology that have emerged in contemporary debate and international negotiations” (taubman , ). there has been much debate about policy settings in respect of intellectual property and clean technologies at the climate change summits — such as the copenhagen accord , the cancun agreements , the durban decisions , the doha climate gateway , the warsaw climate change conference and the lima call for climate action — as well as in international institutions, such as the world intellectual property organization and the world trade organization (rimmer a; rimmer b; rimmer b). there has been prolonged discussion about what flexibilities are available under patent law to provide access to clean technologies. in particular, there has been a focus upon doctrinal options — such as patentable subject matter; patent criteria; technology transfer; patent pools; compulsory licensing; and requirements for disclosure, informed consent, and benefit-sharing. the issue has prominent in the lead-up to the paris climate talks in . ahmed abdul latif ( ), carlos correa ( ) and frederick abbott ( ) have debated the possible law reform options in respect of intellectual property and clean technologies. in the context of the field of biofuels, there has been much policy debate about the appropriate settings for rights and exceptions in patent law, policy, and practice for clean technologies. patentable subject matter it has been long established that micro-organisms (diamond v chakrabarty), plants (j.e.m. ag supply v pioneer hi bred international), and even animals (ex parte allen) are patentable subject matter under united states patent law, and in many other jurisdictions. nonetheless, there has been much uncertainty about the boundaries and the limits of patentable subject matter particularly when grappling with emerging technologies — especially in light of the litigation in the supreme court of the united states in bilski v kappos, mayo collaborative services v prometheus laboratories, association for molecular pathology v myriad genetics, and alice corp. v cls bank international. in his study of synthetic biology, graham dutfield observed that analogies are often drawn with existing technologies — such as mechanical inventions — when assessing the patentability of emerging technologies (dutfield ). a number of technology developers and national governments have promoted biofuels, arguing that they will be a boon to economic development, energy, the environment, and climate change. some commentators have been enthusiastic about the use of patents in respect of biofuels. adam wolek, an intellectual property attorney, argues that patents can help address concerns about the market for biofuels: “patents are particularly crucial for the biofuels industry because large-scale production facilities require standardized procedures and technologies to produce large amounts of uniform fuel” (wolek , ). he elaborated that developers of new biofuels needed proper incentives: “the right to exclude competitors from using a patented technology for twenty years should draw substantial investment and ameliorate many investment concerns, as the potential gains of patenting a technology that becomes an industry standard may outweigh the risk” (wolek , ). wolek concluded that patents are critical for companies wanting to engage in “empire-building” in the area of biofuels (wolek , – ). in the united kingdom, the nuffield council on bioethics considered the question of the regulation of biofuels. the council stressed that “moral values relevant to current and new biofuels include: human rights, solidarity, sustainability, stewardship and justice” (nuffield council on bioethics , ). the council recommended that the future development of biofuels should take into account six principles for ethical policy-making – including ( ) human rights, ( ) environmental sustainability, ( ) climate change, ( ) fair trade, ( ) equitable cost- sharing and benefit-sharing, and ( ) research development (nuffield council on bioethics , xxv). the council contended: “policies for, and regulation of, biofuels have led to or exacerbated ethical problems in the past, so it is important to have a set of ethical principles against which the policies can be evaluated” (nuffield council on bioethics , guide to the report, ). such an approach would emphasize the need to take into account considerations of ethics, justice, and public policy in determinations about patent criteria. there are a number of enterprising biotechnology companies applying a range of genetic and genomic techniques to harvest fuel from algae (waltz ). there has been great interest in the implications of synthetic biology for intellectual property, energy, the protection of the environment and the climate change (ahmann and dorgan ). the etc group — based in canada — has been negative about the adoption of new technologies, such as biofuels and synthetic biology (etc group ). they have argued that such technologies will have adverse impacts in areas such as energy independence, food security, biodiversity, and climate change. the etc group alleged: “under the pretext of addressing environmental degradation, climate change and the energy and food crises, industry is portending a ‘new bioeconomy’ and the replacement of fossil carbon with living matter, now labeled ‘biomass’” (etc group ). the organization was concerned that biofuels threatened food security, particularly in developing countries: “the most productive and accessible biomass is in the global south — exactly where, by , there may be another billion mouths to feed on lands that (thanks to climate chaos) may yield - % less” (etc group ). the etc group has been particularly skeptical about the latest generation of biofuels based upon biotechnology: “although this would seem to be the worst time possible to put new pressures on living systems, governments are being told that ‘synthetic biology’ — a technology just being invented — will make and transform all the biomass we will ever need to replace all the fossil fuels we currently use” (etc group ). the etc group has called for a moratorium in respect of such technologies and for the exclusion of such subject matter from the scope of patent protection. there has been much vigorous debate over the patentability of synthetic biology – particularly in light of previous controversies over gene patents (rai and boyle ; rai and kumar ; dutfield ). technology transfer and climate change the debate over intellectual property and technology transfer is a long standing one, cutting across the fields of public health, biodiversity, energy, and climate health. ahmed abdul latif and pedro roffe from the international centre for trade and sustainable development have provided an overview of the fifty years of international debate over the topic (latif and roffe ). latif and roffe commented: “while multilateral processes cannot provide all the answers, meaningful international action for promoting technology transfer within a general technology acquisition framework is taking shape, as reflected in the recent establishment of a technology mechanism under the united nations framework convention on climate change (unfccc)” (latif and roffe ). over several years, the international climate talks have established a new technology mechanism — known as the unfccc climate technology centre and network (zahar, peel, and godden , – ). the proposal was first mooted by the united kingdom carbon trust and india during international climate discussions. the copenhagen accord , the cancun agreements , the durban decisions and the doha climate gateway established an international framework for the technology mechanism. the warsaw climate change conference established modalities and procedures for the climate technology centre and network and its advisory board. by the time of the lima climate talks , the climate technology centre and network was operational. at the doha climate summit in , the united nations environment programme was selected to administer the unfccc climate technology centre and network (united nations environment programme b). the bid involved a consortium of research centres from around the world. the other key participants in the bid include the united nations industrial development organisation (“unido”) — co-manager of the core centre; the asian institute of technology based in thailand; the bariloche foundation from argentina; the council for scientific and industrial research from south africa; the energy and research institute from india; the environment and development action in the third world from senegal; the tropical agricultural research and higher education center from costa rica; the world agroforestry centre from kenya; the deutsche gesellschaft für internationale zusammenarbeit from germany; the energy research centre of the netherlands; the national renewable energy laboratory from the united states; and the unep risø centre from denmark (united nations environment programme a). this model will facilitate research, development, and diffusion in respect of biofuels. one of the participants in the network is the national renewable energy laboratory (“nrel”). the nrel has an impressive record of research and development in respect of biofuels, emphasized as follows: “through biomass research, nrel is developing technologies to convert biomass—plant matter such as trees, grasses, agricultural residue, algae, and other biological material—to fuels” (nrel a). the nrel stressed: “these biofuels will reduce our nation's dependence on foreign oil, improve our air quality, and support rural economies” (nrel a). the nrel has filed and registered a number of patents in respect of biofuels. the nrel seeks to promote the dissemination of its technologies to the private sector: “through technology partnerships, nrel seeks to reduce private sector risk and enable investment in the adoption of renewable energy and energy efficiency technologies” (nrel b). the nrel commented: “the transfer of these technologies to the marketplace helps displace oil, reduce carbon emissions, and increase u.s. industry competitiveness” (nrel b). naomi oreskes, the co-author of merchants of doubt (oreskes and conway ) has contended that barack obama should make use of the national laboratory system in the united states to address climate change (oreskes ). she laments: “curiosity-driven science has not yet provided the solutions to global warming, and universities are not well situated to address a single, overarching problem” (oreskes ). while she notes that the united states president does not have authority over the nation’s universities, he does have authority over the national laboratory system. oreskes insists that “president obama can move independently of congress to address this critical issue: he can mobilize scientists through the u.s. national laboratory system … the labs have been mobilized before; the time has come to mobilize them again” (oreskes ). at his second inauguration speech in january , president barack obama emphasized: “we will respond to the threat of climate change, knowing that the failure to do so would betray our children and future generations” (obama a). while acknowledging that “[t]he path towards sustainable energy sources will be long and sometimes difficult”, obama insisted: “america cannot resist this transition, we must lead it” (obama a). he also stressed that the united states would defend its intellectual property rights in respect of clean technologies: “we cannot cede to other nations the technology that will power new jobs and new industries, we must claim its promise” (obama, a). the world intellectual property organization has also established wipo green to facilitate information-sharing and technology transfer in respect of clean technologies. this will provide a useful international platform for the diffusion of clean technologies. patent pools there has been much discussion about the use of patent pools, technology clearing houses, and open source strategies to facilitate access to clean technologies (rimmer a, – and – ). jeremy de beer has observed: “so-called patent thickets—multiple upstream patents where overlapping rights may impede the development or commercialization of technology—are an issue of some concern for which cross-licensing and patent pooling have been suggested as a possible solution” (de beer , ). calestous juma and bob bell, jr. have explored the possibility of patent pools in respect of biofuels (juma and bell , ). the pair have been skeptical as to whether patent pools would fully resolve issues in respect of technology transfer: “if patent pools are a possibility in the area of biofuels, they are probably unlikely to change the underlying structural barriers to technology transfer” (juma and bell , ). juma and bell commented that “depending on how a patent pool is organized and implemented, it either cuts through patent-thicket blockages to facilitate access to critical biofuel technologies or can lead to antitrust issues (e.g., where horizontal competitors abuse the system to form an anti-competitive cartel)” (juma and bell , ). the pair has been circumspect about the mechanism: “though patent pools can be a useful intellectual property management tactic with positive implications for access to technologies, they may not be the best way to achieve the transfer of technology” (juma and bell , ). the nuffield council on bioethics summarised its concerns about patent law and biofuels thus: “for biofuels in many cases, financial return will only be possible after the investment of very large sums of money, and intellectual property will play a key role in attempts to secure such a return” (nuffield council on bioethics , – ). nonetheless, the council commented: “just reward also means finding a balance between rewarding parties for their innovation and investment while trying to encourage access to knowledge and materials” (nuffield council on bioethics , – ). the group suggested: “another approach is to influence the way in which intellectual property is exploited – which is done principally through the granting of licences” (nuffield council on bioethics , xxx). the nuffield council on bioethics observed: “the widespread use of non-exclusive licences which utilise the principles and best practices outlined in a recent oecd report should be encouraged in the area of biofuels” (nuffield council on bioethics , xxx). considering the patent clusters in respect of biofuels, there could be scope for patent pools and cross-licensing to facilitate access to key, influential patents. compulsory licensing there has been much international debate about the use of compulsory licensing in respect of clean technologies – including biofuels (rimmer a; rimmer b; rimmer b). developed nations, such as the united states, canada, and members of the european union have been hostile to the provision of compulsory licensing in respect of clean technologies. members of the basic and brics group — including brazil, china, india, and south africa — have pushed for access to clean technologies, but at the same time have made significant patent applications in certain fields. developing countries — members of the group of — have argued that there is a need for the use of flexibilities; in particular, compulsory licensing may provide increased access to clean technologies. calestous juma and bob bell, jr. have evaluated the use of compulsory licensing in respect of biofuels (juma and bell , ). the pair commented: “when there are no close substitutes for a biofuels technological product or process, compulsory licensing may be an option” (juma and bell , ). juma and bell noted further that compulsory licensing can be deployed to deal with a number of public policy objectives — such as addressing anti-competitive conduct. however, the pair were doubtful about the utility of this mechanism, concluding that “compulsory licensing may be a blunt instrument that is unlikely to promote technological innovation” (juma and bell , ). on the subject of compulsory licensing, the nuffield council on bioethics recognised: “many consider compulsory licence provisions as a form of safety valve within intellectual property law, simply designed to moderate the excessive demands of licensors” (nuffield council on bioethics , ). however, the council was hostile to the mechanism: “the compulsory license system is too complex and confrontational to be used except in extreme circumstances to gain access to technology” (nuffield council on bioethics , ). in the council’s view, voluntary forms of patent licensing would be less confrontational and threatening. by contrast, professor carlos correa is somewhat more enthusiastic about the use of compulsory licensing in the area of agriculture — particularly for public policy purposes such as food security, climate change, and energy independence (correa ). he commented that “[a]s an alternative to an uncompensated exception equivalent to the breeders’ exception, patent laws could provide for a remunerative exception based on a compulsory license: a breeder who might be prevented from legally commercializing a new plant variety because it contains one or more third parties’ patented components, may be entitled to obtain a compulsory license on the relevant patent/s” (correa , ). correa recommends that “national patent laws should provide for compulsory licenses in cases where the exploitation of a protected plant variety would infringe a patent” (correa , ). in australia, the productivity commission has considered substantive law reform in respect of patent law and compulsory licensing (productivity commission ), but has only been willing to contemplate limited reforms in respect of compulsory licensing — via a competition test, or a public interest test. the productivity commission has suggested that crown use could be used to address domestic national emergencies and circumstances of extreme urgency. the productivity commission has not addressed the need for compulsory licensing for humanitarian purposes to deal with issues such as food security. in that realm, the productivity commission asserted that compulsory licensing was unlikely to be an effective means to address concerns about global food security (productivity commission ). arguably, though, countries need to develop modern and flexible compulsory licensing regimes to deal with a range of public policy concerns under patent law — including matters such as energy security, food and agriculture, biodiversity, and climate change. the case of biofuels patents highlights the need for the patent regime to be able to address a wide range of public policy concerns. access to genetic resources, informed consent, benefit-sharing, and disclosure the principles of access to genetic resources, disclosure, informed consent, and benefit-sharing have been applied to a wide variety of contexts – including genetic resources, food and agriculture, traditional knowledge and medicine (lawson ). there has been a push to apply the principles of disclosure, informed consent, and benefit- sharing to the topic of patent law and biofuels. the roundtable on sustainable biomaterials has emphasized that “free, prior and informed consent shall form the basis for the process to be followed during all stakeholder consultation, which shall be gender sensitive and result in consensus-driven negotiated agreements” (rsb services foundation ). on the topic of access to genetic resources, the nuffield council on bioethics emphasized: “the intellectual property regime can play a role in ensuring that the costs and benefits associated with biofuels are distributed in an equitable way” (nuffield council on bioethics , xxxi–xxxii). the council suggests that such a goal could be achieved by “taking one of the key objectives of the convention on biological diversity – i.e. the fair and equitable sharing of the benefits arising from the utilisation of genetic resources – and integrating it into the intellectual property regime” (nuffield council on bioethics , xxxii). the nuffield council on bioethics promoted the nagoya protocol for this purpose: “if successful, the nagoya protocol would allow developing countries, in particular, to exploit their genetic resources and reduce possible occurrences of misappropriation of those resources” (nuffield council on bioethics , xxxii). the council had a number of substantive recommendations in respect of access to genetic resources (which is striking, given its limited recommendations on the topics of patent law and plant breeders’ rights). it recommended “that a ‘disclosure of origin’ requirement be introduced into uk patent law to improve transparency about genetic resource use in order to facilitate access and benefit sharing” and that “consideration be given to the introduction of a mandatory ‘disclosure of origin of genetic resources’ requirement in intellectual property law with appropriate sanctions, either outside or within patent law, for non- or incorrect disclosure” (nuffield council on bioethics , ). the council emphasized that such a measure would “help facilitate countries providing genetic resources to monitor compliance with regulations and contracts regarding access to and sharing of benefits from genetic resources, and to bring national policy in line with the bonn guidelines” (nuffield council on bioethics , ). such a disclosure requirement would enable a better consideration of questions on bioethics in respect of biofuel patents. conclusion the topic of intellectual property and biofuels highlights tensions in respect of the larger public policy debate about energy independence, food security, and climate change. the patent landscape and network patent analysis reveal that the field of biofuels has a high concentration of patents. there are significant patent thickets in relation to biodiesel production and bioproducts, biogas, and cellulosic biofuels and by-products. the first generation of biofuels has the largest number of patents, and most influential biofuels networks. the second generation and the third generation of biofuels are still only emerging in terms of influential patent networks. it could be anticipated that there will be greater patent filings in these areas in the future — particularly given the limitations of the first-generation of biofuels. in terms of policy responses, there are a number of pressing issues in relation to patent law and biofuels. there has been much controversy over patent law and biotechnology in respect of limits of patentable subject matter (saez ). in this context, there has been debate over the patentability of biofuels — particularly in respect of later generations of biofuels. there has also been a growing conflict over patents in respect of first-generation biofuels. it can furthermore be anticipated that there will be future conflict over patents relating to second- and third-generation biofuels. the topic of technology transfer remains a significant one in respect of clean technologies, such as biofuels. the unfccc climate technology centre and network will hopefully promote research, development, and diffusion in respect of biofuels. wipo green will also be an important marketplace to trade and share clean technologies. given the crowded nature of the patent landscape, there could be scope for patent pools to facilitate access to key technologies in respect of biofuels. there is a need to modernise compulsory licensing regimes to provide access to clean technologies. furthermore, the topic of biofuels raises important issues about access to genetic resources. there is a need to ensure that patent applications in respect of biofuels comply with requirements in respect of disclosure, informed consent, and benefit-sharing. this will be an important area of debate in the paris climate talks in . there needs to be further international collaboration and co-ordination in respect of the topic of intellectual property law and biofuels — especially given the mutual responsibility for the area between united nations framework convention on climate change , the united nations environment programme, the convention on biological diversity , the international energy agency, the world intellectual property organization, and the world trade organization (rhodes ). bibliography legislation & international materials agreement on trade-related aspects of intellectual property rights, april , , § . 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( ) concepts of property in intellectual property law, cambridge: cambridge university press, – . http://belfercenter.ksg.harvard.edu/files/ditcbcc _en_juma_bell_chapter.pdf http://ictsd.org/i/publications/ / lane, e. ( ) clean tech intellectual property: eco-marks, green patents, and green innovation. oxford and new york: oxford university press. lane, e. ( a) ‘building the global green patent highway: a proposal for international harmonization of green technology fast track programs’ berkeley technology law journal ( ): – . lane, e. ( b) ‘enzyme distributor admits infringement as novozymes wins injunction’ the green patent blog, october, http://www.greenpatentblog.com/ / / /enzyme- distributor-admits-infringement-as-novozymes-wins-injunction/ lane, e. ( c) ‘federal circuit denies butamax’s bid to revive preliminary injunction’ the green patent blog december http://www.greenpatentblog.com/category/biofuels-patents/ lane, e. ( ) ‘court bounces danisco dj premised on pre-patent proclivities’, the green patent blog january http://www.greenpatentblog.com/ / / /court-bounces-danisco- dj-premised-on-pre-patent-proclivities/ lane, e. ( ) ‘the top green ip stories of ’, the green patent blog, january, http://www.greenpatentblog.com/ / / /the-top-green-ip-stories-of- / latif, a. a. ( ) ‘disputed impact, but not to be ignored’, bulletin of the atomic scientists, february, http://thebulletin.org/climate-mitigation-and-intellectual-property- tension #.voq guhp a.twitter http://www.greenpatentblog.com/ / / /enzyme-distributor-admits-infringement-as-novozymes-wins-injunction/ http://www.greenpatentblog.com/ / / /enzyme-distributor-admits-infringement-as-novozymes-wins-injunction/ http://www.greenpatentblog.com/category/biofuels-patents/ http://www.greenpatentblog.com/ / / /court-bounces-danisco-dj-premised-on-pre-patent-proclivities/ http://www.greenpatentblog.com/ / / /court-bounces-danisco-dj-premised-on-pre-patent-proclivities/ http://www.greenpatentblog.com/ / / /the-top-green-ip-stories-of- / http://thebulletin.org/climate-mitigation-and-intellectual-property-tension #.voq guhp a.twitter http://thebulletin.org/climate-mitigation-and-intellectual-property-tension #.voq guhp a.twitter latif, a. a., and roffe, p. ( ) ‘fifty years later, the ip, technology transfer, and development debate lives on’, bridges weekly trade news digest ( ) ( november) http://ictsd.org/i/news/bridgesweekly/ / lawson, c. ( ) regulating genetic resources: access and benefit sharing in international law. cheltenham (uk) and northampton (mass.): edward elgar. lazarus, j. ( ) ‘cleantech patent energy landscape report’, foley and lardner llp http://www.foley.com/ -cleantech-energy-patent-landscape-report- - - / lazarus, j. ( ) ‘cleantech patent energy landscape report’, foley and lardner llp http://www.foley.com/ -cleantech-energy-patent-landscape-report- - - / lazarus, j. ( ) ‘cleantech patent energy landscape report’, foley and lardner llp http://www.foley.com/ -cleantech-energy-patent-landscape-report- - - / lloyd, m., and blows, j. ( ) ‘who holds the power? lessons from hybrid car innovation for clean technologies’, griffith hack patent and trade mark attorneys http://griffithhack.files.wordpress.com/ / /hybrid-cars_oct .pdf lloyd, mike, george mokdsi, and doris spielthenner. . clearing the fog: patenting trends for the treatment of alzheimer's disease. pharmaceutical patent analyst ( ): – . http://ictsd.org/i/news/bridgesweekly/ / http://www.foley.com/ -cleantech-energy-patent-landscape-report- - - / http://www.foley.com/ -cleantech-energy-patent-landscape-report- - - / http://www.foley.com/ -cleantech-energy-patent-landscape-report- - - / http://griffithhack.files.wordpress.com/ / /hybrid-cars_oct .pdf lloyd, m. and spielthenner, d. ( ) ‘who’s in the driver’s seat? what can network patent analysis tell us about toyota’s latest hybrid car litigation?’ ambercite and griffith hack patent and trade mark attorneys, http://www.ambercite.com/downloads/ambercite- hybrid% cars% white% paper.pdf lloyd, m., spielthenner, d. and mokdsi, g. ( ) ‘the smartphone patent wars’ ambercite and griffith hack patent and trade mark attorneys, http://www.griffithhack.com.au/assets/ / /gh_smartphones_final.pdf matondi, p. b., havnevik, k.j., and beyene, a. (ed.) ( ), biofuels, land grabbing, and food security in africa. london: zed books. miller, j. ( ), ‘should juries hear complex patent cases?’ duke law and technology review , http://scholarship.law.duke.edu/cgi/viewcontent.cgi?article= &context=dltr national renewable energy laboratory ( a), ‘biomass research’, http://www.nrel.gov/biomass/ national renewable energy laboratory ( b), ‘technology transfer’, http://www.nrel.gov/technologytransfer/about.html novozymes ( ), ‘update on us patent lawsuit against danisco. press release, may , http://www.novozymes.com/en/investor/news-and-announcements/pages/update-on- us-patent-lawsuit-agains-danisco.aspx http://www.ambercite.com/downloads/ambercite-hybrid% cars% white% paper.pdf http://www.ambercite.com/downloads/ambercite-hybrid% cars% white% paper.pdf http://www.griffithhack.com.au/assets/ / /gh_smartphones_final.pdf http://www.amazon.com/s/ref=ntt_athr_dp_sr_ ?_encoding=utf &field-author=atakilte% beyene&search-alias=books&sort=relevancerank http://scholarship.law.duke.edu/cgi/viewcontent.cgi?article= &context=dltr http://www.nrel.gov/biomass/ http://www.nrel.gov/technologytransfer/about.html http://www.novozymes.com/en/investor/news-and-announcements/pages/update-on-us-patent-lawsuit-agains-danisco.aspx http://www.novozymes.com/en/investor/news-and-announcements/pages/update-on-us-patent-lawsuit-agains-danisco.aspx novozymes ( ), ‘bioenergy – the future of energy’, march http://www.novozymes.com/en/solutions/bioenergy/pages/default.aspx nuffield council on bioethics ( ) biofuels: ethical issues. london: nuffield council on bioethics, http://www.nuffieldbioethics.org/biofuels- obama, b. ( a) inaugural address by president barack obama. the white house, january, http://www.whitehouse.gov/the-press-office/ / / /inaugural-address- president-barack-obama obama, b. ( b) ‘remarks by the president in the state of the union address’ the white house, february http://www.whitehouse.gov/the-press-office/ / / /remarks- president-state-union-address oreskes, n. ( ) ‘mobilizing scientists on climate change’ the washington post, january, http://articles.washingtonpost.com/ - - /opinions/ _ _climate- change-alternative-energy-scientists oreskes, n., and conway, e. ( ), merchants of doubt: how a handful of scientists obscured the truth on issues from tobacco smoke to global warming, new york: bloomsbury press. productivity commission ( ), compulsory licensing of patents, melbourne: australian government, http://www.pc.gov.au/projects/inquiry/patents/report http://www.novozymes.com/en/solutions/bioenergy/pages/default.aspx http://www.nuffieldbioethics.org/biofuels- http://www.whitehouse.gov/the-press-office/ / / /inaugural-address-president-barack-obama http://www.whitehouse.gov/the-press-office/ / / /inaugural-address-president-barack-obama http://www.whitehouse.gov/the-press-office/ / / /remarks-president-state-union-address http://www.whitehouse.gov/the-press-office/ / / /remarks-president-state-union-address http://articles.washingtonpost.com/ - - /opinions/ _ _climate-change-alternative-energy-scientists http://articles.washingtonpost.com/ - - /opinions/ _ _climate-change-alternative-energy-scientists http://www.pc.gov.au/projects/inquiry/patents/report rai, a., and boyle, j. ( ), ‘synthetic biology: caught between property rights, the public domain and the commons’, the public library of science biology ( ), – . rai, a., and kumar, s. ( ) ‘synthetic biology: the intellectual property puzzle’, texas law review ( ), – . rhodes, c. ( ), ‘opportunities and constraint for cooperation between international organisations’, nordic environmental law journal , – . rimmer, m. ( ) ‘genentech and the stolen gene: patent law and pioneer inventions’, bio-science law review ( ), – . rimmer, m. ( a) intellectual property and climate change: inventing clean technologies, cheltenham (uk) and northampton (mass.): edward elgar. rimmer, m. ( b), ‘climate justice for intellectual property at durban’, the conversation ( december), http://theconversation.com/climate-justice-for-intellectual-property-at-durban- rimmer, m. ( a) ‘climate ready crops: intellectual property, agriculture, and climate change’, in rimmer, m. and mclennan, a. (ed.) ( ) intellectual property and emerging http://theconversation.com/climate-justice-for-intellectual-property-at-durban- http://theconversation.com/climate-justice-for-intellectual-property-at-durban- technologies: the new biology, cheltenham (uk) and northampton (mass.): edward elgar, – . rimmer, m. ( b) ‘the doha deadlock: intellectual property and climate change’, the conversation ( december) http://theconversation.edu.au/the-doha-deadlock-intellectual- property-and-climate-change- / rimmer, m. and mclennan, a. (ed.) ( ) intellectual property and emerging technologies: the new biology, cheltenham (uk) and northampton (mass.): edward elgar, – . roundtable on sustainable biofuels ( ) ‘ rsb principles and criteria for sustainable biofuel production’, rsb services foundation http://rsbservices.org/principles- criteria/principles-criteria- / saez, c. ( ) ‘wipo ip indicators: year of records, china tops filings’, intellectual property watch ( december) http://www.ip-watch.org/ / / /wipo-ip-indicators-year- of-records-china-tops-filings/ saez, c. ( ) ‘monsanto, myriad: two us legal cases shaking biotechnology industries’, intellectual property watch ( february) http://www.ip-watch.org/ / / /monsanto- myriad-two-us-legal-cases-shaking-biotechnology-industries/ http://theconversation.edu.au/the-doha-deadlock-intellectual-property-and-climate-change- / http://theconversation.edu.au/the-doha-deadlock-intellectual-property-and-climate-change- / http://rsbservices.org/principles-criteria/principles-criteria- / http://rsbservices.org/principles-criteria/principles-criteria- / http://www.ip-watch.org/ / / /wipo-ip-indicators-year-of-records-china-tops-filings/ http://www.ip-watch.org/ / / /wipo-ip-indicators-year-of-records-china-tops-filings/ http://www.ip-watch.org/ / / /monsanto-myriad-two-us-legal-cases-shaking-biotechnology-industries/ http://www.ip-watch.org/ / / /monsanto-myriad-two-us-legal-cases-shaking-biotechnology-industries/ seba, t. ( ) clean disruption of energy and transportation: how silicon valley will make oil, nuclear, natural gas, coal, electric utilities and conventional cars obsolete by , silicon valley: clean planet ventures. shapiro, c. ( ) ‘navigating the patent thicket: cross licenses, patent pools, and standard- setting’, in jaffe, a., lerner, j., and stern, s. (ed.) ( ) innovation policy and the economy, cambridge: mit press, – . shashikant, s., and khor. m. ( ) intellectual property and technology transfer in the context of climate change. penang: third world network, http://www.twnside.org.sg/title /ipr/pdf/ipr .pdf smith, j. ( ) biofuels and the globalization of risk: the biggest change in north-south relationships since colonialism. london and new york: zed books. stern, n. ( ) a blueprint for a safer planet: how to manage climate change and create a new era of progress and prosperity. london: bodley head. taubman, a. ( ) a practical guide to working with trips, oxford: oxford university press. thisted, t., kjaerulff, s., andersen, c., fuglsang, c.c., (inventors) and novozymes a/s (assignee) ‘alpha-amylase mutants with altered properties’, united states patent no. , , , filing date september , granted may . http://www.twnside.org.sg/title /ipr/pdf/ipr .pdf thompson, s. ( a) ‘biofuel patent trends - ’, industrial biotechnology ( ): – . thompson, s. ( b) ‘biofuel-related us patent trends through early ’, industrial biotechnology ( ): – . thompson, s. ( c) ‘biofuel patent trends and updates as approaches’, industrial biotechnology ( ): – tomes, d., lakshmanan, p., and songstad, d. (ed.) ( ) biofuels: global impact on renewable energy, production agriculture, and technological advancements, new york, dordrecht, heidelberg and london: springer. united nations environment programme ( ), ‘biofuels – new report brings greater clarity to burning issue’, united nations environment programme, october , http://www.unep.org/climatechange/news/pressrelease/tabid/ /language/en- us/default.aspx?documentid= &articleid= united nations environment programme ( a) ‘proposal to host the climate technology centre’, cfp -s , united nations framework convention on climate change, march, http://unfccc.int/files/cooperation_and_support/technology/application/pdf/main_proposal_un ep.pdf/ united nations environment programme ( b), ‘unep to host the new climate technology centre and network’, december, http://www.unep.org/climatechange/news/pressrelease/tabid/ /language/en-us/default.aspx?documentid= &articleid= http://www.unep.org/climatechange/news/pressrelease/tabid/ /language/en-us/default.aspx?documentid= &articleid= http://unfccc.int/files/cooperation_and_support/technology/application/pdf/main_proposal_unep.pdf/ http://unfccc.int/files/cooperation_and_support/technology/application/pdf/main_proposal_unep.pdf/ http://www.unep.org/climatechange/climatechangeconferences/cop /highlights/unepto hostthenewunfcc_ctcn.aspx waltz, e. ( ) biotech’s green gold? nature biotechnology ( ): – . ward, m., and hall, t. ( ) ‘protecting inventions involving biofuel feedstock’ jd supra business advisor http://www.jdsupra.com/documents/ e f -a - d - b - f d .pdf. the white house ( ) president obama announces major initiative to spur biofuels industry and enhance america's energy security. the white house, office of the press secretary august http://www.whitehouse.gov/the-press-office/ / / /president- obama-announces-major-initiative-spur-biofuels-industry-and-en/ wolek, a. ( ) ‘biotech biofuels: how patents may save biofuels and create empires’, chicago-kent law review ( ): – . world intellectual property organization ( ), ‘world intellectual property indicators – edition’. geneva: world intellectual property organization, http://www.wipo.int/ipstats/en/wipi/ / zahar, a., peel, j., and godden, l. ( ) australian climate law in global context. cambridge: cambridge university press. http://www.unep.org/climatechange/climatechangeconferences/cop /highlights/uneptohostthenewunfcc_ctcn.aspx http://www.unep.org/climatechange/climatechangeconferences/cop /highlights/uneptohostthenewunfcc_ctcn.aspx http://www.whitehouse.gov/the-press-office/ / / /president-obama-announces-major-initiative-spur-biofuels-industry-and-en/ http://www.whitehouse.gov/the-press-office/ / / /president-obama-announces-major-initiative-spur-biofuels-industry-and-en/ http://www.wipo.int/ipstats/en/wipi/ / i the keywords for the first generation of biofuels included: ‘starch’, ‘sugar’, ‘animal fats’, ‘vegetable oil’, ‘edible oil’, ‘soy’, ‘soybean’, ‘rapeseed’, ‘jatropha’, ‘mahua’, ‘mustard’, ‘flax’, ‘sunflower’, ‘palm oil’, ‘hemp’, ‘pennycress’, ‘pongamia’, ‘pinnata’, ‘triglyceride’, ‘biodiesel’, ‘diesel’, ‘biogas’, ‘alcohol’, ‘bioalcohol’, ‘ethanol’, ‘butanol’, ‘propanol’, ‘bioethanol’, ‘biobutanol’, ‘biopropanol’ and ‘syngas’. the keywords for the second generation of biofuels included ‘wood’, ‘agricultur’, ‘cellulos’, ‘fibr’, ‘waste’, ‘sewage’, and ‘sludge’. the keywords for the third generation of biofuels included ‘algae’, ‘microalgae’, ‘seaweed’, and ‘algal’. ii there has been significant trade secrets litigation in respect of biofuels: see the united states cases of blueearth biofuels v hawaiian electric company and sunopta, inc. v abengoa bioenergy new technologies, inc.; and the canadian case of abener energia, s.a. v sunopta inc.. 	queensland university of technology 	from the selectedworks of matthew rimmer 	may , 	intellectual property and biofuels: the energy crisis, food security, and climate change 	novozymes a/s v danisco a/s, [ ] fcafc ( february ). australasian legal information institute http://www.austlii.edu.au/cgi-bin/sinodisp/au/cases/cth/fcafc/ / .html. [novozymes a/s v danisco a/s ] 	novozymes a/s v genencor international, inc., [ ] apo ( january ). australasian legal information institute http://www.austlii.edu.au/cgi-bin/sinodisp/au/cases/cth/apo/ / .html 	oreskes, n., and conway, e. ( ), merchants of doubt: how a handful of scientists obscured the truth on issues from tobacco smoke to global warming, new york: bloomsbury press. stratigraphic framework of relatively unexplored section, devonian to basement, eastern kentucky: abstract; tectonics of folded appalachians of pennsylvania as deduced from anthracite region: abstract association round table . the southern tier of counties across new york and the northern tier of counties in pennsylvania. principal prospective zones are middle devonian (onondaga) and silurian reefs and silurian (tuscarora) sandstones at medium depths. . a four-county area in east-central new york, southeast of syracuse, where ordovician oswego and juniata elastics and silurian herkimer sandstones wedge out updip toward the north and east. . a - mi wide subcrop belt of rose run sandstone (ordovician) that trends in an arcuate pattern across east-cen- tral and northeastern ohio, northwestern pennsylvania, and western new york. . the northeast-trending "rome trough" fault system of eastern kentucky and southwestern west virginia. thick cam- brian clastic sections are the principal targets. extensions of this major structural feature southwestward across kentucky and northwestward across west virginia to pennsylvania are being pursued by seismic means. . anticlinal trends in central and eastern pennsylvania and northern west virginia. here fractured reservoirs will be sought along prominent structural features, especially in the tuscarora sandstone and the onondaga-oriskany sections. . shallow medina-clinton (silurian) areas of eastern ohio, northwestern pennsylvania, and western new york. . the entire southwest-trending valley and ridge province from central pennsylvania to northeastern alabama. this area is compared structurally with the prolific gas-producing foot- hills belt of alberta, canada. there are multiple objectives in cambro-ordovician rocks and a possible linear extent of poten- tial gas fields along this trend. also the beekmantown-cooper ridge section, fractured or dolomitized trenton carbonates may be found productive. wilson, e. n., kentucky geol. survey, lexington, ky. stratigraphic framework of relatively unexplored section, devonian to basement, eastern kentucky most of the rocks of cambrian through devonian ages in eastern kentucky change from miogeosynchnal in the south- easternmost part to cratonic as they rise northwestward onto the cincinnati arch. all the systems show thinning and beveling toward the arch, and the cambro-ordovician shows additional post-knox pre-chazy beveling from south to north, apparently reflecting a different pre-cincinnati arch paleogeography. mid- dle and lower cambrian rocks have fullest representation of finer elastics and carbonates in the fault-bounded "rome trough." oil and gas, apparently indigenous, have been obtained from rocks of early and middle cambrian ages. wood, g. h., jr., u.s. geol. survey, washington, d.c. tectonics of folded appalachians of pennsylvania as deduced from anthracite region the anthracite region is the site of several decollements, many large fold systems, and numerous thrust, reverse, and bedding faults. a few of these structural features extend south- westward into maryland and west virginia. detailed surface and mining data in the anthracite region and less-detailed data in the areas on the southwest suggest that the folded appalachians of pennsylvania are characterized by decollements that formed at widespread well-defined changes in rock competency. originating at and rising from each decolle- ment are numerous folds and faults. competent rocks between two decollements commonly are flexed into large simple fold systems and are displaced by a relatively few large faults. in contrast, incompetent rocks be- tween decollements are flexed characteristically into extremely complex fold systems cut by numerous small faults. the de- collements functioned as stress adjustment zones separating difterentially deforming blankets of relatively competent rocks from relatively incompetent rocks. many of the larger anticlines appear to have formed in over- lying rocks where a decollement ramped upward through a part of the sedimentary rocks section. the folded appalachians of pennsylvania probably are sep- arated at depth from the precambrian basement by a master decollement. northwestward gravity sliding induced by vertical uplift of the core of the appalachians and supplemented by lateral compression as the core moved upward seems the most logical explanation for the tectonics of the folded appalachians of pennsylvania. is there a gas shortage? (senator hansen of wyoming entered this article into the u. s. senate congressional record. june , .) it is now common knowledge that u. s. companies have signed agreements with foreign nations such as algeria, libya, and venezuela for buying liquefied natural gas and importing it into the united states at delivered prices much higher than the price of domestically produced natural gas. also, it is no secret that u. s. companies have the blessing of the u. s. government in negotiating with the soviet union for not only the purchases of huge amounts of liquefied natural gas but also for the financing and construction of the facilities to transport the gas to a russian port, liquefaction plants, and the ships necessary to bring the gas to this country. these same companies and others are also planning to build multimillion-dollar plants to produce synthetic gas from naph- tha and crude oil and also coal gasification plants that will require huge capital outlays. the cost of this gas will be four or five times the present cost of natural gas. all of these plans are intended to supplement a dwindling supply of the cleanest and most convenient—and under- priced—of all fuels, natural gas. for the past several years, the nation's use of natural gas has far outrun additions to reserves through new discoveries and we are now faced with the grim prospects of actual shortages and shutdowns in some of the most populous areas of the country, including washington, d.c. the federal power commission, in long overdue action to establish more realistic wellhead pricing policies for natural gas, has been questioned as to whether there is actually as gas shortage by members of both bodies of congress and, in fact, another agency, the federal trade commission last year be- gan its own investigation of the gas shortage at the insistence of a congressional committee. in the meantime, the gas shortage and the impending energy crises are, as one writer put it, being "studied to death." even the ford foundation is now in the act with a $ million grant for an energy policy project. last year a group representing the american association of petroleum geologists' ,(x) members came to washington in an efltort to alert congress and federal officials to the serious- ness of the oil and gas shortage. in that group was dr. sherman a. wengerd, professor of geology at the university of new mexico and now president of aapg. they came to washington because they were concerned with what they termed the looming specter of dropping from an energy "have" to a "have less" nation. they told me during their visit: "it seemed to be almost beyond the comprehension of the people we conferred with that the u. s. could soon experience a real energy crisis." dr. wengerd only a few days ago issued another statement that was published by the oil daily which was highly critical of some who have questioned the fpc's findings of a gas shortage. i would not subscribe to dr. wengerd's charges of demogo- guery to those who questioned the fpc but i do believe his remarks, in view of the seriousness of the gas situation, are worthy of attention by all senators. men like dr. wengerd and other members of aapg know california electricity market crisis: causes, remedies, and prevention - ieee power engineering review c. mensah-bonsu, s. oren california electricity market crisis: causes, remedies, and prevention the competitive electric power market of the stateof california began operation on march with the california independent system operator (california iso) and the now bankrupt power ex- change (px) as the main operationally independent market facilitators. the market took off smoothly, and the prices were seemingly just and reasonable until may , when the first signs of market crisis emerged. this marked the beginning of the california powercrisis thatcontinueduntil aboutmay .dur- ing that period, california was confronted with an un- precedented electricity crisis that threatened to undermine the reliability of its electricity system, weaken its economy, and impact energy markets throughout the western part of the united states. root causes of the crisis the initial causes of the high wholesale market prices reflect a complex mixture of: � drought conditions that reduced hydroelectric powerproduction(particularly in thenorthwest re- gion)andcorrespondinglowpower-import levels � growingeconomythat fueleddemandforpower � dramaticallyhigherandvolatilenaturalgasprices � lack of sufficient generating capacity in califor- nia and throughout the u.s. western region � inadequate transmission infrastructure � inadequate demand responsiveness or lackof de- mand elasticity � lack of forward contracting � forward scheduling that resulted in thehuge reli- ance on the spot market � federal energy regulatory commission’s (ferc) hands-off approach in regulating whole- sale markets. these anomalies, among others, culminated into a “perfect storm”andconsequently led to the significant marketpowerabuses incalifornia.theproblemswere further compoundedby thepotential financial insolvencyof the investor-owned utilities (iou). the increasing deterioration of the financial solvency of california’s three ious further shat- tered all vestiges of a “normal” deregulated electricity market. effectively, the california iso, ious, and state government overseers had to resort to desperate measures in keeping the lights on in california with the limited available resources. the crisis had its origins in the unintentional mistakes and miscalculationsadoptedat the time theelectricity sectorwas re- structured in california through the assembly bill (ab ) in . two mistakes stand out as critical. � california required utilities to make nearly all their elec- tricity purchases on a volatile spot basis, divest a substan- tial portion of their generation without allowing them to enter into long-termcontracts toensurestableand“reason- able”pricesduring the transitionperiod followingderegu- lation.the lackofdemandresponsiveness tohourlyprices - / /$ . © ieee ieee power engineering review, august c. mensah-bonsu is with the california iso, folsom, california, usa. s. oren is with the university of california, berkeley, california, usa. © d ig it a l s t o c k authorized licensed use limited to: univ of calif berkeley. downloaded on march , at : : edt from ieee xplore. restrictions apply. werepartly due to technical capa- bility limitationfor real timeprice responsiveness, ambiguous ac- countability for the acquisition of reasonably-pricedpowerfor retail consumers, and lack of adequate forward contracting for energy. transition contracts are found in every successful electricity mar- ket, as well as in other unregu- lated commodity markets, and are particularly important where the utilities divest generation but haveobligations to serve remain- ing customers. � california froze retail rates at low levels and banked on low whole- saleprices tosupportaprofitmar- gin high enough to enable the utilities to pay off historical, un- economic investments, including strandedcosts.althoughfrozenat % below levels, the rates were supposedly high at the time compared to what a competitive market would presumably have produced. the fixed retail level price discouraged end-users from undertaking nor- mal market responses: to conserve and/or to take advan- tage of the allowed customer choice and opt for an alternative retail supplier. those responses would have helped restrain prices. inmay ,wholesalemarketpricessoareddue to risingde- mand, and dramatically fixed retail prices blocked conservation effortsbyinsulatingconsumersfrommarketrealitiesandreduced consumer incentives to turn to competitive retailers. the heavy reliance on spot market purchases, combined with demand that was unresponsive to prices, helped drive prices higher. impact of stakeholders and credit-worthiness the energy prices were low to moderate in the first years. however, the iousmanaged to sell a goodportionof their gen- eration assets at attractive prices, expediting the recovery of stranded costs, presumably due to the reliability must-run (rmr) contracts that most of the divested units had, which en- abled them to sell above book value. unfortunately, the utilities hadalreadydivestedmostof their generationplantswithoutbe- ing allowed by the california public utility commission (cpuc) to secure contracts that would have ensured their right tobuyback thepowerat somefixedback-stopprice.thecpuc felt that suchcontractswouldaddunnecessarycosts toconsum- ers’electricitybills andwereconcernedabout “self-dealing”by theutilities.thedivestituresofgenerationassets by theutilities that were encouraged and sanctioned by the cpuc exposed the utilities to the financial costs associated with high wholesale (purchase) prices and low fixed-retail (sale) prices. meanwhile, the iouswere losingmoneyon theelectricity theywerebuying for resale to their customers.the inversionof the typicalwhole- sale-retail price relationship brought these utilities to the brink ofbankruptcy.theperceived riskofnonpayment in turncaused generators to be reluctant suppliers, even at dramatically ele- vated wholesale prices. the natural reluctance of suppliers to supply voluntarily when they did not expect to get paid was a substantial contributor to the rising prices and rolling blackouts that were seen in california in the early months of . the destruction of the utilities’credit-worthiness and the re- sulting responsesby suppliers shattered all vestiges of anormal market. consequently, california had to deal with both a finan- cial crisis and an electricity supply crisis. with the utilities’ credit quality destroyed, suppliers fearful of not being paid for their supplies became reluctant to sell into the california mar- ket. in effect, the utilities and their state government overseers had to resort todesperatemeasures tokeep the lightsonwith the available limited resources, with only limited success. ca iso energy control center employees worked diligently to keep the lights on, a task thatwason-goinguntil fercorderedamarket mitigation framework in collaboration with the california iso indecember to ensure stability, and“just and reasonable” prices in the california iso electricity markets. however, this framework,whichwasorderedbyferctostop the“bleeding,” expires on september . ieee power engineering review, august a section of the california iso control room, with (left to right): anjali sheffrin, director of the department of market analysis; chris mensah-bonsu, market design engineer, market operations; mark rothleder, manager of market integration california crisis and its impact on worldwide energy markets this article is part of a series on the california energy crisis of and its impact on other energy markets and their deregulatory/reregulatory actions. these articles are based on presentations given at two separate technical ses- sions held during the ieee pes summer meeting in vancouver, british co- lumbia, canada: california electricity market crisis: causes, remedies and prevention was chaired by chris mensah-bonsu of the california iso; is dereg- ulation at a dive after california? a view from the rest of the world, was chaired by t.j. hammons of the university of glasgow. both sessions provided learned opinions of the causes of the crisis and tried to assess possible aftereffects on the regulatory processes occurring worldwide. i took the liberty of selecting the articles that i considered most relevant. i hope you enjoy them and gain some new insight into the complexity of the over- all process. bill schwartz, editor in chief (continued on page ) authorized licensed use limited to: univ of calif berkeley. downloaded on march , at : : edt from ieee xplore. restrictions apply. 	index: 	ccc: - - - / /$ . © ieee 	ccc: - - - / /$ . © ieee 	cce: - - - / /$ . © ieee 	index: 	index: 	ind: 	intentional blank: this page is intentionally blank doi: . /j.cell. . . previews able and the results will surely provide further intrigu- ing insights. already, it is clear that the dscam exon array uses a new mechanism to achieve me splicing. rather than resulting from an absolute physical impediment to splicing, me behavior appears to arise as an intrinsic consequence of the regulatory mechanism used to se- lect individual exons. how the docker:selector struc- ture might lead to derepression is one of many open questions. the docker:selector duplex might bind to an activator that antagonizes the repressor. alternatively, the single-stranded selectors might be intron-splicing silencers to which the repressor binds. these possibili- ties would be distinguished by the effects of selector mutation. a particularly puzzling feature of the model is how docker-selector pairing is regulated. the exon . selector is only bases downstream of the docker, whereas that of . is over kb distant. if docker- selector pairing were dictated on a cotranscriptional “first-come, first-served” basis (eperon et al., ), there would be an overwhelming preference for selec- tion of the # proximal exon variants, but this is not observed. neither does the predicted thermodynamic stability of selector:docker pairs correlate with the fre- quency of selection of the associated exons. both ob- servations strongly suggest that selector:docker pair- ing must be regulated, although the manner of such regulation remains to be elucidated. open questions notwithstanding, the docker-selector model is so im- mediately attractive that it seems surprising that it does not obviously apply to any of the other arrays of dro- sophila me exons, not even in dscam. perhaps the power of persistent staring and luck (see experimental procedures in graveley, ) will unlock their secrets and possibly reveal some general mechanistic prin- ciples underlying this complex form of alternative splicing. christopher w.j. smith department of biochemistry tennis court road cambridge, cb ga united kingdom selected reading buratti, e., and baralle, f.e. ( ). mol. cell. biol. , – . eperon, l.p., graham, i.r., griffiths, a.d., and eperon, i.c. ( ). cell , – . graveley, b.r. ( ). cell , this issue, – . graveley, b.r., kaur, a., gunning, d., zipursky, s.l., rowen, l., and clemens, j.c. ( ). rna , – . gromak, n., matlin, a.j., cooper, t.a., and smith, c.w.j. ( ). rna , – . jin, y., suzuki, h., maegawa, s., endo, h., sugano, s., hashimoto, k., yasuda, k., and inoue, k. ( ). embo j. , – . jones, r.b., wang, f., luo, y., yu, c., jin, c., suzuki, t., kan, m., and mckeehan, w.l. ( ). j. biol. chem. , – . letunic, i., copley, r.r., and bork, p. ( ). hum. mol. genet. , – . neves, g., zucker, j., daly, m., and chess, a. ( ). nat. genet. , – . park, j.w., parisky, k., celotto, a.m., reenan, r.a., and graveley, b.r. ( ). proc. natl. acad. sci. usa , – . schmucker, d., clemens, j.c., shu, h., worby, c.a., xiao, j., muda, m., dixon, j.e., and zipursky, s.l. ( ). cell , – . smith, c.w.j., and nadal-ginard, b. ( ). cell , – . doi . /j.cell. . . a cellular response to an internal energy crisis lack of an appropriate energy supply has been thought to induce cell death in a nonspecific manner by causing a decline in metabolism and a gradual cessation of cellular function. in this issue of cell, nutt et al. ( ) describe a new mechanism that di- rectly links nutrient availability to apoptosis in xeno- pus oocytes and show that age-dependent changes in the nutritional state of a cell might lead to caspase activation and apoptotic cell death. under normal physiological conditions, most cell types in our body obtain their energy from nutrients that are present in abundance in the extracellular environment. the availability of these nutrients to each cell is “ra- tioned” by the limited amount of trophic factors that control nutrient uptake. only a few select cell types, such as oocytes, are “self-sufficient” and rely entirely on internal energy stores for survival. thus, oocytes are an interesting model in which to study the events that occur during a cellular energy crisis. in this issue of cell, nutt et al. ( ) explore the biochemical events that take place when oocytes exhaust their internal en- ergy stores and define a new pathway regulating cell survival in response to nutrient depletion. previous studies have demonstrated that oocytes can be induced to undergo apoptosis regulated by cas- pases, a family of aspartic proteases necessary for the execution of apoptotic cell death, as well as by both the pro- and antiapoptotic members of the bcl- family of apoptotic regulators. to address how the availability of nutrients may regulate oocyte apoptosis, the authors used oocyte extracts from the frog xenopus laevis. they demonstrated that depletion of stores of glucose- -phosphate (g p), an intermediate of glucose metab- olism, caused the loss of an inhibitory phosphorylation of caspase- by the ca +/calmodulin dependent kinase ii (camkii), thereby activating caspase- and resulting in apoptosis. they also showed that caspase- activa- tion occurs upstream of apoptotic events in the mito- chondria. this suggests that activation of this protease is an initiating event linking glucose depletion to the induction of apoptosis in oocytes. caspase- is an up- stream caspase involved in the initiation of apoptosis induced by cellular stress caused by factors such as dna damage (tinel and tschopp, ). however, the phenotype of mice deficient in caspase- revealed sur- prisingly little other than the resistance of their oocytes to dna damage and naturally occurring cell death (bergeron et al., ). the data in the nutt et al. paper cell may finally explain the phenotype of these mice. if oo- cytes undergo apoptosis in response to insufficient nu- trients, then the loss of caspase- , a proposed media- tor of cell death induced by nutrient depletion, would result in resistance to apoptosis. although it is apparent from this study that, during oocyte apoptosis, caspase- operates upstream of mito- chondrial events and may exert its effects through reg- ulation of the bcl- family, it is not clear which members might be involved. although the bcl- family member bad may mediate the apoptotic response to glucose deprivation, bad is regulated through phosphorylation rather than by cleavage by caspases (danial et al., ). other proapoptotic bcl- family proteins known to be regulated by caspase-dependent cleavage, such as bid, are possible candidates. the substrate specific- ity of caspase- is unusual, and very few substrates of caspase- have been identified. in the presence of active caspase- , there is still a lag time until induction of apoptosis in oocyte extracts, indicating that addi- tional signaling steps might also be involved in the sup- pression of apoptosis by glucose in this system. nutt et al. ( ) suggest that a sensor of intracellular energy levels may be an important direct regulator of the apoptotic cascade in oocytes. it is not clear what might serve as the upstream molecular sensor of glu- cose levels signaling to caspase- . although the ratio of atp to adp and camp levels have been previously reported to mediate cellular responses to energy and nutrients, they are unlikely to play a direct role in this case. the authors demonstrate that suppression of cas- pase- -mediated apoptosis by g p depends on the con- tinued operation of the pentose cycle and production of nadph. in fact, nadph can suppress caspase- activa- tion in oocyte extracts in the absence of g p. there- fore, the energy sensor operating in this system may be measuring nadph or the ratio of nadph to nadp+. the findings described by nutt et al. ( ) may be applicable to other cellular systems. caspase- is in- volved in the programmed cell death of mouse sympa- thetic neurons deprived of nerve growth factor (ngf). given that ngf also regulates glucose uptake in neu- rons, it is conceivable that caspase- could be acti- vated in sympathetic neurons deprived of ngf due to the reduction in intracellular glucose levels. other cas- pases may also be involved in mediating apoptosis in- duced by energy crisis. for example, caspase- has been implicated in the apoptosis of human hepatoma cells induced by glucose starvation (suzuki et al., ). in this system, caspase- is activated upstream of apoptotic events in mitochondria. caspase- activa- tion is suppressed by a new member of the amp- dependent protein kinase family, ark . although the mechanism of inhibition of caspase- by ark in this system is not clear, this kinase is known to block the activity of caspase- through phosphorylation (suzuki et al., ). therefore, altering the phosphorylation state of caspases may represent a common mecha- nism to control the induction or repression of apoptosis in response to cellular energy levels. direct coupling of cellular glucose metabolism to caspase activation has a number of important implica- tions. first, it suggests that glucose metabolism may play a larger part in tissue homeostasis than previously a s o c m p g t g b p p t f p a g l t t t o h p r p t w v b l i w a o t l c a s a d s a i r l s w m v m t a t i r h l o ppreciated. although glucose is generally in abundant upply in the extracellular environment of a multicellular rganism, the uptake of glucose is regulated by extra- ellular trophic factors and their intracellular signaling ediators (recently reviewed in hammerman et al., ). the best characterized of these mediators is the roto-oncogene akt. akt can directly regulate cellular lucose uptake by inducing expression of the glucose ransporter, glut , at the plasma membrane and tar- eting hexokinase activity to the mitochondria, possi- ly in part through its ability to influence the inhibitory hosphorylation of bad. the ability of activated akt to romote cell survival has been recently demonstrated o depend on glucose availability because, in glucose- ree media, constitutively active akt is unable to sup- ort sustained cell viability despite the availability of an lternative energy source. the importance of sustained lucose metabolism for the effects of akt is further il- ustrated by the fact that enhancement of glucose up- ake and utilization can partially restore cell viability in he absence of akt function (rathmell et al., ). hus, we can consider glucose as an essential cofactor f akt signaling. it is interesting to speculate that per- aps the reason that the prosurvival effects of akt de- end on the presence of glucose is because glucose is equired to suppress the caspase- -mediated apo- totic pathway. this hypothesis would further predict hat, perhaps in caspase- -deficient cells, akt activity ould no longer require the presence of glucose. furthermore, coupling metabolic state and cell sur- ival may provide a mechanism for regulating cell num- ers during aging at both the cellular and organismal evel. nutt et al. ( ) noted an age-related decrease n the activity of g p dehydrogenase in murine oocytes, hich could contribute to their decreased viability. it is ttractive to speculate that a similar mechanism may perate in other tissue types such as neurons or hepa- ocytes, which are particularly sensitive to glucose evels and are affected by deleterious age-related hanges. proteins involved in ca + signaling (including n isoform of camkii), camp signaling, map kinase ignaling, cell survival, and mitochondrial metabolism re among those downregulated in response to dna amage during aging of the human brain (lu et al., ). these changes could directly contribute to the lowing of cellular metabolism observed during normal ging, leading to lower internal levels of glucose and, n sensitive tissues, contributing to the decline in cell esistance to proapoptotic stimuli and eventual cell oss. additionally, age-related changes have been ob- erved in hormone and growth-factor expression, hich could indirectly affect both survival and cellular etabolism through their effects on akt and other sur- ival pathways. in either case, the gradual decline in etabolism and intracellular glucose could directly lead o cell death through either activation of caspase- or an lternative proapoptotic pathway. it has long been appreciated that nutrient depriva- ion due to either growth-factor withdrawal, embolism- nduced loss of blood supply, or age- and disease- elated changes in metabolism can lead to cell death. owever, it has been assumed that lack of nutrients is ikely to induce cell death due to the gradual shutdown f cellular metabolism and consequent cessation of all previews cellular functions. the data presented by nutt et al. ( ) demonstrate that nutrient deprivation is, instead, directly linked through caspase- to the apoptotic ma- chinery and that active suppression of this pathway by continuous glucose metabolism is required for survival. the fact that this pathway can be activated due to age- related changes also suggests that metabolic decline may contribute directly to cellular and organismal aging by inducing caspase activation. marta m. lipinski and junying yuan department of cell biology harvard medical school longwood avenue boston, massachusetts selected reading bergeron, l., perez, g.i., macdonald, g., shi, l., sun, y., jurisicova, a., varmuza, s., latham, k.e., flaws, j.a., salter, j.c., et al. ( ). genes dev. , – . danial, n.n., gramm, c.f., scorrano, l., zhang, c.y., krauss, s., ranger, a.m., datta, s.r., greenberg, m.e., licklider, l.j., lowell, b.b., et al. ( ). nature , – . hammerman, p.s., fox, c.j., and thompson, c.b. ( ). trends biochem. sci. , – . lu, t., pan, y., kao, s.y., li, c., kohane, i., chan, j., and yankner, b.a. ( ). nature , – . nutt, l.k., margolis, s.s., jensen, m., herman, c.e., dunphy, w.g., rathmell, j.c., and kornbluth, s. ( ). cell , this issue, – . rathmell, j.c., fox, c.j., plas, d.r., hammerman, p.s., cinalli, r.m., and thompson, c.b. ( ). mol. cell. biol. , – . suzuki, a., kusakai, g., kishimoto, a., lu, j., ogura, t., and esumi, h. ( ). oncogene , – . suzuki, a., kusakai, g., kishimoto, a., shimojo, y., miyamoto, s., ogura, t., ochiai, a., and esumi, h. ( ). oncogene , – . tinel, a., and tschopp, j. ( ). science , – . doi . /j.cell. . . 	a cellular response to an internal energy crisis 	selected reading [pdf] alternative mechanisms of inhibiting activity of poly (adp-ribose) polymerase- . | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /s corpus id: alternative mechanisms of inhibiting activity of poly (adp-ribose) polymerase- . @article{sriram alternativemo, title={alternative mechanisms of inhibiting activity of poly (adp-ribose) polymerase- .}, author={chandra shaker sriram and ashok jangra and b. bezbaruah and v athirak and shivaji sykam}, journal={frontiers in bioscience}, year={ }, volume={ }, pages={ - } } 	chandra shaker sriram, ashok jangra, + authors shivaji sykam 	published 	chemistry, medicine 	frontiers in bioscience poly adp-ribose polymerase (parp- ), a dna nick-sensor enzyme, is an abundant nuclear protein. upon sensing dna breaks, parp- gets activated and cleaves nad into nicotinamide and adp-ribose and polymerizes the latter onto nuclear acceptor proteins including histones, transcription factors, and parp- itself. poly(adp-ribosylation) mainly contributes to dna repairing mechanism. however, oxidative stress-induced over-activation of parp- consumes excess of nad and consequently atp, culminating… expand view on pubmed bioscience.org save to library create alert cite launch research feed share this paper citationsbackground citations view all figures and topics from this paper 	 figure 	adenosine diphosphate 	ribose 	parp protein, human 	cerebrovascular accident 	necrosis 	niacin 	poly a 	oxidative stress 	diabetes mellitus 	neoplasms 	traumatic brain injury 	brain injuries 	myocardial ischemia 	neutrophil actin dysfunction 	nicotinamide adenine dinucleotide (nad) 	transcription factor 	inhibition 	histones 	dysplastic nevus citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency adenoviral vectors for modulation of poly(adp-ribose) polymerase- (parp ) – dependent dna repair as a predictive tool for chemotherapy 	r. meyer, mirella l. meyer-ficca, jan-heiner kuepper 	biology 	 	 	 save alert research feed adenoviral vectors for modulation of poly ( adp-ribose ) polymerase- ( parp ) – dependent dna repair as a predictive tool for chemotherapy 	r. g. meyera, m. l. meyer-ficcaa, j.-h. küpperc 	 	view excerpt, cites background save alert research feed the nad+-dependent family of sirtuins in cerebral ischemia and preconditioning. 	n. khoury, kevin b. koronowski, j. young, miguel a. perez‐pinzon 	biology, medicine 	antioxidants & redox signaling 	 	 	 	view excerpts, cites background save alert research feed acetyl- -keto-β-boswellic acid prevents testicular torsion/detorsion injury in rats by modulating -lox/ltb and p -mapk/jnk/bax/caspase- pathways. 	maha a e ahmed, a. a. e. ahmed, e. m. el morsy 	chemistry, medicine 	life sciences 	 	 save alert research feed references showing - of references sort byrelevance most influenced papers recency multiple facets of poly(adp-ribose) polymerase- in neurological diseases 	chandra shaker sriram, ashok jangra, rajaram mohanrao madhana, s. s. gurjar, p. mohan, b. bezbaruah 	medicine, biology 	neural regeneration research 	 	 	pdf 	view excerpt, references background save alert research feed poly(adp-ribose) catabolism triggers amp-dependent mitochondrial energy failure* 	l. formentini, a. macchiarulo, + authors a. chiarugi 	biology, medicine 	the journal of biological chemistry 	 	 	 	view excerpts, references background save alert research feed inhibition of poly(adp-ribose) polymerase- or poly(adp-ribose) glycohydrolase individually, but not in combination, leads to improved chemotherapeutic efficacy in hela cells 	xiaoxing feng, d. w. koh 	biology, medicine 	international journal of oncology 	 	 	pdf 	view excerpt, references background save alert research feed targeting poly(adp-ribose)polymerase in neurological diseases: a promising trove for new pharmacological interventions to enter clinical translation 	c. s. sriram, ashok jangra, e. r. kasala, l. n. bodduluru, b. bezbaruah 	biology, medicine 	neurochemistry international 	 	 	view excerpts, references background and methods save alert research feed poly(adp-ribose) polymerase mediates the suicide response to massive dna damage: studies in normal and dna-repair defective cells. 	n. berger, j. l. sims, d. m. catino, s. j. berger 	biology, medicine 	princess takamatsu symposia 	 	 	view excerpt, references background save alert research feed minor grove binding ligands disrupt parp- activation pathways 	k. kirsanov, e. kotova, + authors a. tulin 	biology, medicine 	oncotarget 	 	 	pdf 	view excerpts, references background save alert research feed poly (adp-ribose) polymerase- inhibitor, -aminobenzamide pretreatment ameliorates lipopolysaccharide-induced neurobehavioral and neurochemical anomalies in mice 	chandra shaker sriram, ashok jangra, s. s. gurjar, md iftikar hussain, b. bezbaruah 	chemistry, medicine 	pharmacology biochemistry and behavior 	 	 	view excerpts, references background save alert research feed inhibition of poly(adenosine diphosphate-ribose) polymerase by the active form of vitamin d. 	j. mabley, rebecca wallace, p. pacher, kanneganti murphy, c. szabo 	biology, medicine 	international journal of molecular medicine 	 	 	 save alert research feed parp- inhibition increases mitochondrial metabolism through sirt activation. 	p. bai, c. cantó, + authors j. auwerx 	biology, medicine 	cell metabolism 	 	 	 	view excerpts, references background save alert research feed parg dysfunction enhances dna double strand break formation in s-phase after alkylation dna damage and augments different cell death pathways 	h. shirai, a. poetsch, + authors m. masutani 	biology, medicine 	cell death and disease 	 	 	pdf 	view excerpts, references background save alert research feed ... ... related papers 	abstract 	figures and topics 	 citations 	 references 	related papers stay connected with semantic scholar sign up about semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue dynamic analysis of an offshore wind turbine including soil effects procedia engineering ( ) – - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer- review under responsibility of organizing committee , iit madras , and international steering committee of apac doi: . /j.proeng. . . sciencedirect available online at www.sciencedirect.com th international conference on asian and pacific coasts (apac ) department of ocean engineering, iit madras, india. dynamic analysis of an offshore wind turbine including soil effects k.a. abhinav, nilanjan saha* adepartment of ocean engineering, iit madras, chennai , india abstract offshore wind turbines (owts) offer an attractive, sustainable solution to the impending global energy crisis. a major challenge in fixed-bottom owt design is accounting for soil-structure interaction (ssi) under the influence of random dynamic loading from wind, waves and currents. usually, ssi is either ignored in owt studies or is incorporated by means of simplified foundation concepts like the apparent fixity model. owts in shallow water depths (less than m) are mostly supported on monopiles - large diameter steel pipe piles driven into the subsoil. monopiles transfer the dynamic lateral loads into the soil by bending action. the present work deals with the dynamic analysis of the nrel mw owt on a monopile foundation, in indian waters. it involves parametric studies on various clayey soil profiles - soft, medium stiff and stiff clay. an operational wind speed of m/s and a sea state of m significant wave height and s spectral peak period are considered. the owt design should ensure that the natural frequency is away from the forcing frequencies of wind, wave and rotor. a water depth of m is considered. hub-height aerodynamic loads are obtained using the nrel-fast code, which is based on the blade- element momentum (bem) theory. the hydrodynamic time domain analyses are performed in the fem based coupled hydrodynamic - geotechnical software, dnv-gl - usfos. usfos makes use of the jonswap spectrum to generate irregular waves. soil is represented by means of p-y, q-z and t-z curves. results indicate the significance of including ssi in owt studies. variation in response due to change in pile penetration depth and pile diameter are also highlighted. stiffness of clay is the design driver for owts. © the authors. published by elsevier b.v. peer-review under responsibility of organizing committee, iit madras, and international steering committee of apac * corresponding author. tel.:+ - - ; fax:+ - - . e-mail address:nilanjan@iitm.ac.in © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer- review under responsibility of organizing committee , iit madras , and international steering committee of apac http://crossmark.crossref.org/dialog/?doi= . /j.proeng. . . &domain=pdf k.a. abhinav and nilanjan saha / procedia engineering ( ) – keywords:offshore wind turbine, soil-structure interaction, monopile . introduction offshore wind turbines are gaining popularity as the need to offset the nonrenewable energy crisis is being recognized. owts in shallow waters are usually supported on monopile substructures, which are essentially large diameter piles in the range of - m. monopiles transfer lateral loads from wind and waves by bending action, into the soil. unlike oil and gas structures, owt systems are subjected to heavy lateral loads, often to the tune of % of the vertical loading (lesny, ). this calls for a comprehensive dynamic analysis, especially in soft soils, where the natural frequency of the system could undergo significant variations (bazeos et al., ). laterally loaded piles are designed using the p y method specified by the api ( ). however, these soil curves are derived from experiments involving small diameter piles and their validity for monopile design is still being debated (achmus and abdel-rahman, ). lesny and wiemann ( ), haiderali et al. ( ), achmus et al. ( ) etc. have made use of quasi-static mudline loads to investigate the response of monopiles. abhinav and saha ( ) analysed for a jacket subjected to random wave loads considering soil structure interaction while, gao et al. ( ) showed that jacket structure can be analysed as a set of monopiles of varying diameters. abs ( ) followed a quasi-aerostatic-hydrodynamic approach to study owt response under different water depths. bisoi and haldar ( ) analyzed a mw owt under dynamic loads, including soil-structure interaction (ssi) here, the aerodynamic load at the hub was modelled as a function of the rotor frequency. the present work deals with the analysis of a monopile support structure for the nrel mw baseline owt, under aerodynamic and hydrodynamic loads, for varying soil conditions. the fem-based code usfos (sintef group, ) is used for hydrodynamic analysis. usfos implements a nonlinear fe formulation based on green strain e (valid for all magnitudes of rotation and displacement), where a finite element represents an actual element of the structure. this pre-empts the choice of mesh-size and speeds up computation. the hht-α method is used for dynamic analysis. aerodynamic loads are derived using an aeroelastic code, fast (jonkman and buhl, ). three different clayey soil profiles - soft, medium stiff and stiff clay - are considered. the effects of soil stiffness variation, pile penetration depth and pile diameter, on the lateral response and natural frequency of the owt structure are investigated. soil stiffness is derived using the soil curves specified by api ( ). results show significant variations in the response and point towards the need for detailed modelling of soil-structure interaction in the analysis of owt structures. . numerical modeling . . structural model the nrel mw baseline owt, conceptualized by jonkman et al. ( ), is considered in the present study. the numerical model of a monopile supporting the nrel mw owt, in a water depth of m is developed in usfos. the turbine rotor-nacelle-assembly (rna) is supported by a steel tower, connected to the monopile through a cylindrical transition piece. the diameter and thickness of the tower varies from m and . m respectively, at the base, to . m and . m respectively, at the top. the components of the owt structure and the corresponding design levels are represented in figure . a higher density value is considered for steel ( kg/m ) to account for the absence of bolts, flanges and welds in the model. the monopile has a diameter of m and is founded on uniform stiff clay. two other soil profiles (medium-stiff clay and soft clay) are also considered for the analysis, to investigate the response of the structure under dynamic loads. the soil profiles are defined in table . here, γ is the submerged unit weight, su is the undrained shear strength and ε is the strain at % of maximum stress in undrained compression test. the depth of embedment is taken as m or times the pile diameter. the wall thickness ( t ) of the monopile is defined by api ( ), on the basis of its diameter ( d ), as shown in equation . k.a. abhinav and nilanjan saha / procedia engineering ( ) – . d t ( ) fig. . owt conceptual and fe model table . soil profiles soil type γ (kn/m ) su (kpa) ε soft clay . medium stiff clay . stiff clay . the tower and piles are modelled using -noded beam elements. all analyses are performed for an operational hub-height wind speed of m/s and a sea-state defined by a significant wave height ( sh ) of m and wave spectral peak period ( pt ) of s. . . modelling of soil-structure-interaction soil-structure interaction is modelled in usfos using lateral and axial nonlinear spring-to-ground elements along the length of the pile. the properties of the spring elements are derived from the p y , t z , and q z , curves recommended by api ( ). pile-soil interaction in the lateral direction is accounted for, by the lateral soil resistance - deflection or p y curves, while that in the vertical direction is modelled using the curves for skin friction ( t z ) and end bearing ( q z ). more information on the development of cyclic p y curves for soft and stiff clays is described in reese and van impe ( ). k.a. abhinav and nilanjan saha / procedia engineering ( ) – . . modelling parameters the owt is located in a water depth of m in clayey soil. the hub height wind speed is m/s. simulations are performed for duration of s. a time step value of . s has been used for dynamic analysis. soil springs are attached to the pile at a distance of m. a frequency value of is used for the discretizing the jonswap spectrum by constant area method. . description of loads owt are subjected to the action of aerodynamic and hydrodynamic loading. usfos has coupled hydrodynamic and geotechnical modules. however, the absence of an aerodynamic component requires the use of a separate code for the same. according to seidel et al. ( ) and gao et al. ( ), the response of an owt can be accurately realized using decoupled analyses, if its natural period varies significantly from the predominant wave period. the fundamental vibration mode of the owt involves the vibration of the tower, indicating the lack of a significant contribution of wave loading, to this mode. this is consistent with the findings in gao et al. ( ) and points to a lack of strong coupling between wind and wave loads. hence, a decoupled analysis could be used to model the response of the owt. the present work ignores the influence of wind loading on the tower of the owt. the modeling concepts for dynamic loading are discussed below. . . aerodynamic loads aerodynamic loads on the nrel mw owt are computed using the fast code. nrel's turbsim code (jonkman, ) is used to generate stochastic wind fields corresponding to a hub-height wind speed of m/s. the kaimal spectrum (kaimal et al., ) is used in conjunction with the normal turbulence model (iec, ) to realize -component wind speed vectors encompassing the entire rotor plane. fast makes use of the blade element momentum theory (moriarty and hansen, ) to generate time-series of aerodynamic load components at the hub of the owt. . . hydrodynamic loads wave loading on slender structures like piles are calculated using the morison equation (chakrabarti, ). here, the total load is obtained as the summation of drag and inertia components, arising from the velocity and acceleration of water particles, respectively. morison equation gives the hydrodynamic force (f) per unit length of the vertical pile as: . m d d f c c u uu π ρ ρ ( ) where d is the diameter of the pile, u is the horizontal water particle velocity, . u is the water particle acceleration, ρ is the density of water and ,m dc c are hydrodynamic coefficients of inertia and drag, respectively. the dot represents acceleration. long-crested irregular waves for dynamic analyses are modelled using the constant area discretization of the joint north sea wave project (jonswap) spectrum. the jonswap spectrum is valid for fetch-limited seas and homogenous wind conditions. . results and discussion the generation of time series for stochastic wind and wave loading involves the use of pseudo-random number generators for realizing the random phases (zwick and muskulus, ). the use of different random seeds for the k.a. abhinav and nilanjan saha / procedia engineering ( ) – same wind (or wave) data results in different time-series and hence, statistical uncertainty. this has to be taken care of by multiple simulations, involving different seed numbers. the results present herein are mean values from an ensemble size of , involving different seed numbers for generating wind and wave time series. . . effect of soil variability on natural frequency of owt as stated in bhattacharya et al. ( ), a -bladed owt is excited at the following: (a) the rotor frequency ( p), (b) the blade pass frequency ( p), (c) the wave loads and (d) the gusty winds. economic considerations dictate that the frequency of the owt lies in between the p and the p regions. this is termed as the soft-stiff design, which corresponds to a frequency band of . hz to . hz for the nrel mw-owt. it is observed, from table , that softening soils tends to increase the period of vibration and hence, result in a reduction in natural frequency. in the case of soft-clay, the natural frequency was found to dip into the unsafe p region, where the owt structure becomes vulnerable to resonance. pile penetration depth of m and diameter of m is considered for analysis. table . variation of natural frequency soil type natural frequency (hz) soft clay . medium stiff clay . stiff clay . . . effect of soil variability on lateral response of owt for the considered pile penetration depth of m, medium stiff and stiff clayey soil profiles show a variation of % in the lateral displacement at the mudline and % at the tower-top, respectively, as shown in figure . the displacement of the owt in soft clay is exceeds the serviceability limit of . m at mudline. k.a. abhinav and nilanjan saha / procedia engineering ( ) – fig. . effect of soil variability fig. . effect of pile diameter variation . . effect of pile diameter on lateral response of owt three different pile diameters were considered for a penetration depth of m, in stiff clay - m, m and m. the thickness of the piles is defined according to equation . it is observed from figure , that an increase in pile diameter brings about a reduction in the lateral response of the owt. this is due to the fact that the stiffness obtained from a p y curve is proportional to the diameter of the pile. . . effect of pile depth on lateral response of owt stiff clay exhibits the same displacement profile for pile penetration depths from m to m. medium stiff clay shows an increase in displacement with reduction in pile penetration depth. these results are shown in figures a and b. a marked difference in the displacement of the embedded portion of the pile is also observed. for smaller penetration depths, the response of the owt in soft clay escalates and this results in failure of the system. k.a. abhinav and nilanjan saha / procedia engineering ( ) – fig. a. medium stiff clay fig. b. stiff clay . conclusions decoupled aero-hydrodynamic simulations on a monopile in clay of varying stiffness underscore the importance of considering ssi in owt studies. softer soils increased the time-period of vibration and hence the natural frequency of the owt shifted to the resonant region. soil stiffness is the determining factor in the performance of owts in clayey soils. soft clays were found to produce excessive motions that transcend the serviceability limit state, leading to failure. stiff clays, on the other hand, produced relatively constant response with varying pile depth and diameter. similar analysis is required to be extended for sandy soils as well as mixed soils, which would form a part of the future work. acknowledgements the authors would like to thank dr. tore holmas for his help with usfos. the authors gratefully acknowledge the financial support given by the earth systems science organization, ministry of earth sciences, government of india through national institute of ocean technology to conduct part of the research. references abs, . design standards for offshore wind farms, american bureau of shipping, houston, usa abhinav ka and saha, n., . coupled hydrodynamic and geotechnical analysis of jacket offshore wind turbine, soil dyanmics and earthquake engineering, , pp. - . achmus, m., kuo, y-s., abdel-rahman, k., . behavior of monopile foundations under cyclic lateral load, computers and geotechnics, – achmus, m., abdel-rahman, k.,. . design of piles for offshore wind energy foundations with respect to horizontal loading, proceedings of the twenty-second international offshore and polar engineering conference, isope, rhodes, greece, - k.a. abhinav and nilanjan saha / procedia engineering ( ) – api, . api-rp- a - recommended practice for planning, designing and constructing fixed offshore platforms - working stress design, american petroleum institute, washington, d.c., usa bazeos, n., hatzigeorgiou, g.d., hondros, i.d., karamaneas, h., karabalis, d.l., beskos, d.e., . static, seismic and stability analysis of a prototype wind turbine steel tower, engineering structures, , – bhattacharya, s., nikitas, n., garnsey, j., alexander, n.a., cox, j., lombardi, d., muir wood, d., nash, d.f.t., . observed dynamic soil–structure interaction in scale testing of offshore wind turbine foundations, soil dynamics and earthquake engineering, , - bisoi, s., haldar, s., . dynamic analysis of offshore wind turbine in clay considering soil–monopile–tower interaction, soil dynamics and earthquake engineering, , - chakrabarti, s.k., . handbook of offshore engineering - volume -i, elsevier, amsterdam, the netherlands gao, z., saha, n., moan, t. , amdahl, j., . dynamic analysis of offshore fixed wind turbines under wind and wave loads using alternative computer codes, proceedings of the rd eawe conference, torque : the science of making torque from wind, crete, greece haiderali, a., cilingir, u., madabhushi, g., . lateral and axial capacity of monopiles for offshore wind turbines, indian geotechnical journal, ( ): - iec., . iec - - wind turbines – part : design requirements for offshore wind turbines, international electrotechnical commission, geneva, switzerland jonkman, b.j., . turbsim user's guide v . , technical report nrel/tp- - , national renewable energy laboratory, golden, co, usa jonkman, j.m., buhl, m.l. jr., . fast user's guide, technical report nrel/el- - , national renewable energy laboratory, golden, co, usa jonkman, j.m., butterfield, s., musial, w., scott, g., . definition of a -mw reference wind turbine for offshore system development. technical report nrel/tp- - , national renewable energy laboratory, golden, co, usa kaimal, j.c., wyngaard, j.c., izumi, y., cote, o.r., . spectral characteristics of surface-layer turbulence, quarterly journal of the royal meteorological society, , – lesny, k., wiemann, j., . design aspects of monopiles in german offshore wind farms, in: frontiers of offshore geotechnics, eds. gourvenec, s., cassidy., m, taylor & francis group, london, pp - lesny, l., . foundations for offshore wind turbines, vge verlag gmbh, essen, germany moriarty, p. j., hansen, a.c., . aerodyn theory manual, technical report nrel/el- - , national renewable energy laboratory, golden, co, usa reese, l.c., van impe, w.f., . single piles and pile groups under lateral loading, crc press/balkema, leiden, the netherlands seidel, m., ostermann, f., curvers, a.p.w.m., kuhn, m., kaufer, d., boker, c., . validation of offshore load simulations using measurement data from the downvind project. conference proceedings of european offshore wind, stockholm, sweden sintef group, . usfos-getting started, structural engineering, marintek zwick, d., muskulus, m., . the simulation error caused by input loading variability in offshore wind turbine structural analysis, wind energy (available online) doi: . /we. unknown • jaoa • vol • no • june the proposed etiology of travell trigger points (trps) has undergone a fundamental revision in recent years. new research results suggest that trps are evoked by the abnormal depolarization of motor end plates. this article expands the proposed etiology to include presynaptic, synaptic, and postsynaptic mechanisms of abnormal depo- larization (ie, excessive release of acetycholine [ach], defects of acetylcholinesterase, and upregulation of nico- tinic ach-receptor activity, respectively). this working hypothesis regarding the etiology of trps has changed the approach to treating trps. as an example, travell and simons abandoned the application of ischemic compression to trps; instead the authors adopted several techniques associated with osteopathic medicine (ie, muscle-energy, myofascial, counterstrain; high-velocity, low-amplitude). scientists are now proposing and reporting the results of new approaches using cap- saicin, a vanilloid-receptor agonist, and ach antagonists (eg, dimethisoquin hydrochloride, botulinum toxin, quini- dine, linalool). the purpose of this article is to review these new concepts and describe new resulting approaches to the treatment of trps. janet g. travell, md, ( – ) was an internist in gen-eral medicine who developed an interest in spinal manip- ulation in the s, but later shifted her focus to myofascial trigger points (trps). in , she relieved then–senator john f. kennedy of disabling back pain (after he endured a failed diskectomy in and laminectomy in ). travell’s ensuing post as white house physician, followed by the publication of her two-volume “red bible,” myofascial pain and dysfunction: the trigger point manual, , coauthored with david g. simons, md, brought prominence to her approach for treating trps. travell defined a trp as “a hyperirritable spot in skeletal muscle that is associated with a hypersensitive palpable nodule in a taut band. the spot is tender when pressed and can give rise to characteristic referred pain, motor dysfunc- tion, and autonomic phenomena.” an example of this is shown in figure . the taut band of muscle is best charac- terized as a palpable, ropy structure. palpation is a reliable diagnostic criterion for locating trps in patients. the reliability of diagnosing trps is similar to the reliability of diagnosing tender points in the counter- strain system developed by lawrence h. jones, do. an interrater-reliability study of this counterstrain system demon- strated that clinicians agreed % of the time (� = . ); the palpation of patients’ trps proved more reliable than the standard osteopathic tart examination. (tart is a mnemonic for the four criteria of somatic dysfunction: tissue texture abnormality, asymmetry, restriction of motion, and tenderness. ) myofascial trigger points can be inactivated by a variety of approaches, including osteopathic manipulative treatment (omt), massage therapy, ultrasound therapy, “spray and stretch,” as well as needling (acupuncture or injection). a full account that describes the diagnosis and treatment of travell trps is provided by kuchera and mcpartland in foundations for osteopathic medicine. this article serves as a companion piece to kuchera and mcpartland’s chapter in foundations, describing a new working hypothesis regarding the etiology of trps and the way in which this new hypoth- esis changes our treatment of these points. most of the mate- rial in this article was mistakenly deleted from the final ver- sion of the foundations chapter. proposed etiology of trps the edition of travell and simons’ myofascial pain and dys- function: the trigger point manual proposes an “integrated hypothesis” regarding the etiology of trps. such an integrated hypothesis involves local myofascial tissues, the central nervous system (cns), and biomechanical factors. a biopsy of local myofascial tissue in the vicinity of trps revealed that the tissues contained “contraction knots,” described as “large, rounded, darkly staining muscle fibers and a statistically significant increase in the average diameter of muscle fibers.” electromyographic (emg) studies of trps have indicated spontaneous electrical activity (sea) in trps, while adjacent muscle tissues are electrically silent. these intersecting discoveries led travell and simons to implicate dysfunctional motor end plates as the underlying etiology of trps. the terms motor end plates and neuromuscular junction from unitec institute of technology in auckland, new zealand. address correspondence to john m. mcpartland, do, ms, faculty of health & environmental science, unitec institute of technology, private bag , auckland, new zealand. e-mail: jmcpartland@unitec.ac.nz review article mcpartland • review article travell trigger points—molecular and osteopathic perspectives john m. mcpartland, do, ms jaoa • vol • no • june • review article mcpartland • review article acquired defects many ion channels and neuroreceptors are expressed by more than one gene. these genetic subtypes are expressed in cells in different parts of the body for different needs and at different points in the life cycle. dysregulated expression of these genes will produce acquired defects. to illustrate this mechanism, consider the genes that encode nachr subunits. the gene that encodes a cns nachr may become dysregulated in a muscle cell and may begin producing cns nachrs in the motor end plate. couple this dysfunction with tobacco smoking. nicotine normally activates cns achrs and not motor end plate achrs. if dysregulated, however, cns nachrs become expressed in motor end plates. nicotine would then activate those receptors in motor end plates, poten- tially causing trps. single genes may also become dysregulated should they express splice variants. splice variants are alternative ways in which a gene’s protein-coding sections (exons) are joined together to create a messenger ribonucleic acid molecule and its translated protein. for example, ache expresses several sub- types that are produced by alternative splicing of the single ache gene. these subtypes are induced under psycholog- ical, chemical, and physical stress. the simple upregulation of certain genes may lead to muscle hyperexcitability and evoke trps in muscles. for example, l-type and n-type ca � channels are upregulated by factors associated with physical and psychological stress, , as well as by nicotine. patients with trps and long-term mus- culoskeletal pain should avoid tobacco smoking, as well as excess caffeine. caffeine upregulates activity at motor end plates by acting as an agonist of ryanodine receptors and an antagonist of adenosine a a receptors. motor end plate dysfunction cascade when a motor end plate becomes dysfunctional, several per- verse mechanisms cause it to persist as a trp. the excessive muscle contraction compresses local sensory nerves, which reduces the axoplasmic transport of molecules that normally inhibit ach release. , the sustained muscle contraction also compresses local blood vessels, reducing the local supply of oxygen. this impaired circulation, combined with the increased metabolic demands generated by contracted muscles, results in a rapid depletion of local adenosine triphosphate (atp). the resultant “atp energy crisis” triggers presynaptic and postsynaptic decompensations. in the nerve terminal, atp directly inhibits ach release, so depletion of atp increases ach release. in the muscle cell, atp powers the ca � pump, which returns calcium to the sarcoplasmic reticulum. hence, loss of atp impairs the reuptake of ca �, which increases contractile activity—a vicious cycle. the atp energy crisis cascades into a local release of chemicals that activate or sensitize nociceptive nerves in the region, including bradykinins, cytokines, serotonin, histamine, potassium, prostaglandins, leukotrienes, somatostatin, and are interchangeable, although the first term describes structure and the latter reflects function. both terms refer to the point where �-motor neurons contact their target muscle fibers. (see figure for a schematic drawing of a motor end plate.) the cor- relation between motor end plates and trps (“myalgic spots”) was first elucidated in a study conducted by gunn and mil- brandt in . travell and simons attributed motor end plate dysfunc- tion to an excessive release of acetylcholine (ach) from the presynaptic motor nerve terminal. , acetylcholine released into the synaptic cleft rapidly activates nicotinic ach receptors (nachrs) on the postsynaptic muscle membrane, leading to a muscle action potential and muscle contraction (figure ). travell and simons’ hypothesis of a presynaptic dysfunction, however, is only one way to interpret the results of emg studies. as the emg electrodes are placed in postsynaptic muscle fibers, the increased sea measured in trps could be attributed to the result of presynaptic, synaptic, or postsy- naptic dysfunction. all of these dysfunctions can be inherited (genetic) or acquired. genetic defects gene mutations frequently arise as nucleotide polymorphisms (snps, pronounced “snips”) and microsatellite polymorphisms. single nucleotide polymorphisms are common deoxyribonu- cleic acid (dna) variations among individuals, caused by a single-point mutation. microsatellite polymorphisms are mutated dna loci that contain nucleotide repeats. pellegrino et al implicated genetic factors in the formation of trps. genetic defects of motor end plates can be presynaptic, synaptic, or postsynaptic. presynaptically, the release of ach depends on the calcium ion (ca �) concentration in the �- motor nerve terminal. excessive release of ach may be caused by defects of l-type and n-type voltage-gated ca � chan- nels. an internet search of the snp catalog maintained by the national center for biotechnology information (available at: http://www.ncbi.nlm.nih.gov) reveals reports of l-type ca � channel mutations and reports of n-type ca � channel mutations. thus, a genetic cause for excess ach release may be quite common. synaptically, ach is normally inactivated by the enzyme acetylcholinesterase (ache) (figure ). genetic defects of ache may cause excess ach to remain in the synaptic cleft. postsynaptically, a gain-of-function defect of nachr may confer muscle hyperexcitability, a hallmark of travell trps. the nachr is an assembly of subunits; at least genes encode nachr subunits that combine in a variety of ways. thus, nachr is particularly susceptible to mutation defects. the nachr in the motor end plate expresses different subunits than nachr expressed in the cns or in the autonomic nerves. gain-of-function mutations result in the overexpression of nachrs in the muscle cell membrane, as well as resulting in nachrs that are hypersenstive to ach. these mutations also result in nachrs that become constitutively active. • jaoa • vol • no • june review article mcpartland • review article substance p. this chemical activation and sensitization of nociceptors accounts for trp tenderness. sensitizing substances may also generate a focal demyelination of sensory nerves. demyelination creates abnormal impulse–generating sites (aigs) capable of generating ectopic nociceptive impulses. cns and biomechanical factors the cns and biomechanical factors also contribute to the for- mation and maintenance of trps. a persistent barrage of noci- ceptive signals from trps will eventually sensitize the cns, a process termed central sensitization. this process accelerates in the presence of aigs and their associated ephaptic crosstalk (cross-excitation) with neighboring autonomic nerves. travell and simons’ view of the cns as an “integrator” of trps is interchangeable with korr’s description of the cns as an “organizer” of somatic dysfunction. according to travell and simons, the sensitized dorsal horn becomes a “neurologic lens,” consolidating other nociceptive signals converging on the same segment of the spinal cord, including other somatic dys- functions and visceral dysfunctions. biomechanical factors that stress muscles (eg, acute trauma, repetitive microtrauma) contribute to trp dysfunc- tion. further, biomechanical stress of a cold muscle is a key factor in the formation of trps, - as cooling muscles apparently upregulate nachr activity at the motor end plates. the revised edition of travell and simons’ manual emphasizes the relationship between trps and nearby articular dysfunc- tions. in the manual, the authors correlate suboccipital trps with occipitoatlantal (oa) dysfunctions, semispinalis capitus trps with oa dysfunctions and atlantoaxial dysfunctions, and splenius trps with upper thoracic articular dysfunctions. postural disorders often contribute to the perpetuation of trps. for example, postural strain of the suboccipital mus- cles may cause trps in these muscles, leading to further dete- rioration in muscle structure and function. such deterioration may result in radiating pain (figure ) and atrophic changes. suboccipital muscles contain a high density of propriocep- tors, so atrophic changes lead to a loss in proprioceptive bal- ance and loss of proprioceptive “gate control” at the dorsal horn, giving rise to chronic pain syndromes. considerations for osteopathic medicine twenty years ago, travell and simons treated trps with “ischemic compression” by applying heavy thumb pressure on trps, sufficient to produce skin blanching. in the edition, travell and simons recommend applying gentle digital pres- sure to trps. this fundamental change is anchored in travell’s atp energy crisis model, which characterizes trps as centers of tissue hypoxia. thus, deep digital pressure that produces additional ischemia is not beneficial. travell and simons named their new technique “trigger point pressure release.” applying a “press and stretch” technique is believed to restore abnor- mally contracted sarcomeres in the contraction knot to their normal resting length. it is an indirect technique that uses the barrier-release concept, in which the finger “follows” the releasing tissue. during the past years, travell and simons developed an appreciation for omt, though they learned of it from euro- pean allopathic physicians. the authors began treating trps with a muscle-energy technique they called the “lewit tech- nique.” karl lewit, md, from the czech republic, developed his technique after working with fred l. mitchell, jr, do, philip e. greenman, do, and other osteopathic physicians. a dutch variation of lewit’s method, the “gaymans-lewit technique,” evolved after gaymans met osteopathic physi- cians in new york city in the early s. travell and simons subsequently cited mitchell and greenman and described muscle energy and myofascial release. travell and simons’ revised edition of their manual advo- cates muscle energy, counterstrain, myofascial release, and figure . trigger point of the left rectus capitis posterior major (marked by an x) and its referred pain pattern (stip- pling). (adapted in part from travell et al. ) jaoa • vol • no • june • review article mcpartland • review article other new approaches for treating trps travell and simons recommend dimethisoquin hydrochlo- ride ointment (quotane) for massaging trps in superficial muscles such as the orbicularis oculi, frontalis, and occipi- talis. dimethisoquin, a local anesthetic, inhibits voltage-gated na(�) channels (conferring its anesthetic effect) but also acts as a noncompetitive inhibitor of nachrs (ic = . �m). the anesthetic’s potency is significantly greater than that of lido- caine (ic = �m) and procaine (ic = �m). further, dimethisoquine is uniquely selective for the nachr subtype expressed in the neuromuscular junction. massage with capsaicin cream ( . %, available over the counter) is useful for treating trps located in surgical scars, which are particularly refractory to treatment. cap- saicin selectively binds to the vanilloid receptor (vr ). vanil- loid-receptor activation triggers an influx of ca � into neuron terminals, which initiates neurotransmitter release. repeated exposure to capsaicin, however, causes vr s to become desen- sitized. this mechanism explains the seemingly paradoxical use of capsaicin as an analgesic. - vanilloid receptors are also expressed in brain regions that modulate the emotive and cognitive aspects of pain (eg, preoptic area, locus ceruleus, hypothalamus, striatum). it has been hypothesized that mod- ulating the expression of vr s and their endogenous ligand (anandamide) may be one of the central mechanisms of omt, parallel to the potential effects of omt on endorphins. needling is sometimes necessary to inactivate trps. for thousands of years, chinese medicine has treated trps with acupuncture. travell began needling trps with syringes in , injecting them with procaine. procaine was later replaced by saline solution, which was later replaced by “dry needling”—without any fluid in the syringe —bringing the procedure full circle to what is essentially acupuncture. the “dysfunctional motor end plate hypothesis” has led to the injection of botulinum toxin, which causes an irreversible blockade of ach release in the trp. injecting trps with quinidine should be tested in a clinical trial, as quinidine decreases presynaptic ach release (via its well-known blockade of l-type ca � channels) and down- regulates nachrs (a postsynaptic mechanism). in one trial, quinidine appeared to restore ache activity. diltiazem also merits investigation. it is an l-type ca � channel blocking agent that corrects myopathies caused by defects in ache activity. travell and simons recommended a diet adequate in vitamins and minerals for the prevention of trps. supple- menting the diet with phosphatidylcholine has been recom- mended, but this may actually provoke trps in a portion of patients. as choline is a percursor to ach, an nachr gain-of- function mutation may enable choline to directly activate the mutated receptors. another new approach in treating trps are herbal med- ications. as an estimated % of patients with long-term mus- culoskeletal pain take herbal remedies, it behooves osteopathic other omt techniques for treating trps and associated artic- ular somatic dysfunctions. in addition, high-velocity, low- amplitude thrust techniques are illustrated, hearkening back to travell’s early interest in spinal manipulation. figure . the motor end plate—proposed site of trigger point dys- function. top illustration: the junction between the �-motor neuron and the muscle fiber. the �-motor neuron terminates in multiple swellings termed synaptic boutons. bottom illustration: presynaptic boutons are separated from the postsynaptic muscle cell by the synaptic cleft. within each bouton are many synaptic vesicles containing ach, clus- tered around dense bars (db). the db is the site of ach release into the synapse. across the synapse from the db, the postsynaptic muscle cell membrane forms junctional folds that are lined with nicotinic ach receptors (nach). ach released into the synapse activates nach receptors, then is inactivated by the acetylcholinesterase enzyme (ache). (adapted in part from kandel et al. ) • jaoa • vol • no • june review article physicians to understand the mechanisms of these medica- tions. herbal remedies and essential oils that are recom- mended for treating myofascial pain include lavender (lavan- dula angustifolia), lemon balm (melissa officinalis), rosemary (rosmarinus officinalis), kava kava (piper methysticum), skullcap (scutellaria lateriflora), passionflower (passiflora incarnata), rose (rosa spp), and valerian (valeriana officinalis). nearly all of these herbs contain linalool, a monoterpene compound that inhibits end plate activity by reducing ach release (a presy- naptic mechanism) and by modifing nachrs (a postsynaptic mechanism). marijuana (cannabis spp), which also produces linalool, also effectively treats myofascial pain syndromes. marijuana’s efficacy may also be attributed to tetrahydro- cannabinol, an n-type ca � channel blocker. tetrahydro- cannabinol inhibits ach release in the cns ; this inhibition is thought to occur at motor end plates, as motor nerve terminals express cannabinoid receptors. conclusion travell and simons’concepts regarding trps have converged with osteopathic medicine’s concept of somatic dysfunction. this convergence is also seen in travell and simons’ approach to the treatment of trps, which in many ways resembles the omt used in chapman reflex points, jones’ counterstrain points, and the progressive inhibition of neuromuscular structures (pins) technique. armed with a better under- standing of the molecular basis underlying myofascial pain syn- dromes, clinicians hope that travell and simons’ approach will continue to coevolve with osteopathic concepts. references . travell w, travell jg. technic for reduction and ambulatory treatment of sacroiliac displacement. arch phys ther. ; : - . . travell jg. office hours: day and night; the autobiography of janet travell, md. new york, ny: world publishing co; . . travell jg, simons dg. myofascial pain and dysfunction: the 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treatment of myofascial pain syndrome. pain. ; : - . mcpartland • review article plants , , ; doi: . /plants www.mdpi.com/journal/plants editorial plant responses to hypoxia: signaling and adaptation elena loreti ,* and gustavo g. striker ,* institute of agricultural biology and biotechnology, cnr, national research council, via moruzzi, pisa, italy ifeva, conicet, cátedra de fisiología vegetal, facultad de agronomía, universidad de buenos aires, av. san martín , buenos aires c dse, argentina * correspondence: elena.loreti@ibba.cnr.it (e.l.); striker@agro.uba.ar (g.g.s.) received: november ; accepted: november ; published: december . introduction molecular oxygen deficiency leads to altered cellular metabolism and can dramatically reduce crop productivity. nearly all crops are negatively affected by lack of oxygen (hypoxia) due to adverse environmental conditions such as excessive rain and soil waterlogging. extensive efforts to fully understand how plants sense oxygen deficiency and their ability to respond using different strategies are crucial to increase hypoxia tolerance. it was estimated that % of crop losses are due to floods [ ]. progress in our understanding has been significant in the last years. this topic deserved more attention from the academic community; therefore, we have compiled a special issue including four reviews and thirteen research articles reflecting the advancements made thus far. . advances in hypoxia sensing and responses oryza sativa (rice) is an important crop widely used in areas prone to suffer waterlogging and submergence. this special issue has contributions that address essential aspects related to its tolerance to the lack of oxygen. publications that address rice aspects include reviews on the molecular regulatory pathways and the metabolic adaptation in the seed germination and early seedling growth [ , ]. a first review examines in detail aspects about the coleoptile elongation under submergence, anaerobic gene regulation in rice coleoptile, chromosomal regions regulating coleoptile elongation under oxygen shortage, starch degradation during anaerobic germination, and the hormonal regulation of anaerobic rice coleoptile elongation [ ]. a second review focuses on the recent advances underlying anaerobic germination and coleoptile elongation and highlights the prospect of introducing quantitative trait loci (qtl) for anaerobic germination into rice mega varieties [ ]. in addition, interesting experimental information—indicating that chlorophyll retention, content, low hydrogen peroxide accumulation, and catalase activity are related to better performance under submergence in seedlings of five japonica rice varieties—is also shown [ ]. conversely, another paper examined the potassium efflux and cytosol acidification as primary anoxia-induced events in wheat and rice seedlings and found that rice responses were more distinct and reversible upon reoxygenation when compared with sensitive wheat [ ]. root aeration is essential to withstand water excess scenarios such as waterlogging [ ]. the formation of aerenchyma in roots is critical to enable the diffusive oxygen transport to reach the root tips. additionally, this longitudinal transport of oxygen towards root tips can be constrained if there is an excessive radial loss of oxygen towards the rhizosphere (rol). hence, the presence of a barrier preventing rol is a desirable trait for more efficient root aeration. in this regard, it is shown for rice that auxin-mediated signaling contributes to ethylene-dependent inducible aerenchyma formation in roots [ ]. it was demonstrated that an auxin transport inhibitor stopped aerenchyma formation under oxygen-deficient conditions and reduced the expression of genes encoding ethylene biosynthesis plants , , of enzymes [ ]. complementarily, another contribution assessed the formation of barrier to oxygen loss of four genotypes from two wild rice species (oriza glumaepatula and o. rufipogon) and found that the three o. glumaepatula accessions formed a rol barrier constitutively, while the accession of o. rufipogon accession did not [ ]. therefore, these wild relatives’ selected accessions might be crossed with elite commercial rice materials to incorporate or improve this root trait aiming at better root aeration when waterlogged [ ]. the traits aiding to the recovery from submergence-induced hypoxia have been less examined and identified than those conferring tolerance during the stress period. a detailed study in the legume lotus japonicus showed genotypic variation in the recovery ability (rgr) from short-term complete submergence and a trade-off between growth during vs. after the stress. in addition, an inverse relationship between growth after submergence and the shoot to root ratio (sr) was identified, where genotypes with low values of sr were able to maintain high stomatal conductance, a better leaf water status, and chlorophyll retention [ ]. among the consequences of flooded plants are the involvement of hormone and metabolic responses as well as enhanced production of reactive oxygen species (ros). to achieve progress in the mechanisms underlying anoxia tolerance is crucial to develop a broader view considering interactions between different signaling pathways. an exciting overview of the hypoxia field’s classical and recent findings is reported in this special issue [ ]. the review summarizes various aspects of low oxygen stress: (i) hypoxia sensing; (ii) adaptation to hypoxia at the cellular level; (iii) environmental hypoxia; and finally (iv) developmental hypoxia representing a physiologically relevant condition for the functionality of specific plant tissues [ ]. the molecular mechanism of oxygen perception has been revealed in plants where proteins belonging to group vii ethylene response factors (efr-viis) play a pivotal role in becoming stable under hypoxia and degraded by proteasome machinery under aerobic conditions [ , ]. a new contribution provides information about the function of the jatropha curcas erfviis and the consequent n-terminal modification that stabilized the protein under low oxygen availability [ ]. it was shown that jcerfvii is an n-end rule regulated waterlogging-responsive transcription factor that modulates gene expression under different stress-responsive conditions, including low-oxygen, oxidative, and pathogen response [ ]. the involvement of hormones during hypoxia stress demonstrated that in root apical meristem, crosstalk between hypoxia and ja signaling occurs [ ]. the jasmonate synthesis is initially enhanced but later decreased probably due to lack of oxygen and a consequent energy crisis [ ]. previous research has shown that when low oxygen occurs, ethylene signal drives hypoxia responses and improves survival in arabidopsis [ , ]. a new paper showed that the hypoxia response triggered by ethylene is conserved in solanum species, and, as it occurs in arabidopsis, it enhances hypoxia tolerance [ ]. one of ethylene signaling effects is hydrogen peroxide (h o ) production that acts as a second messenger. to clarify the relationship between ethylene and h o under low oxygen availability the rbohd/ein - double mutant plants was analyzed under hypoxic stress [ ]. the results demonstrated a synergistic interaction between ethylene and h o signaling in modulating seed germination, seedling root growth, leaf chlorophyll content, and hypoxia-inducible gene expression [ ]. in medicago truncatula, the metabolic response differs between shoots and roots tissue [ ]. analyzing the composition of phloem exudate sap, they demonstrated that roots and leaves have distinct metabolic responses. overall, the metabolomic data suggest that the decrease in sugar import in waterlogged roots increases the phloem sugar pool, which exerts a negative feedback regulation on sugar metabolism in shoots tissue [ ]. in recent years, a group of non-coding rna molecules, micrornas (mirnas), were identified. they play a pivotal role in different cellular processes. among them, it was proposed to have a role in response to environmental stresses triggering the repression of target genes [ ]. taking advantage of high-throughput small rna sequencing, a group of micornas was identified in maize and teosinte under two crucial environmental stresses, submergence and drought and alternated stresses. plants , , of therefore, the identified mirnas are a good starting point to establish the roles of mirnas in stress response and could be useful for improving stress tolerance [ ]. finally, some practical aspects are also approached by articles on this special issue for other agricultural species. for instance, in physalis peruviana (cape gooseberry), it was reported that foliar glycine betaine or hydrogen peroxide sprays ameliorate waterlogging stress, and that these can be potentially used as tools in managing waterlogging in this horticultural andean fruit crop species [ ]. additionally, in pisum sativum (pea) it was proved that the application of a hypoxic treatment decreases the physiological action of the herbicide imazamox due to an amelioration of the effects on total soluble sugars, starch accumulation, and changes in some amino acids [ ]. this allows the authors to suggest that fermentation might constitute a plant defense mechanism that decreases the herbicidal effect [ ]. finally, a complete revision of the state of the art is provided regarding the findings that explain the traits conferring tolerance to root hypoxia in woody fruit species [ ]. special attention is given to the strategies for managing the energy crisis in prunus species, and less explored topics in recovery and stress memory in woody fruit trees are pointed out. . future perspectives the studies briefly summarized above provide an advance in our understanding of the molecular basis, the ecophysiological traits, and some of the genetic diversity of the model species arabidopsis thaliana, lotus japonicus, and medicago truncatula. they also increase our understanding of some agricultural species (rice and its wild relatives, wheat, cape gooseberry, alfalfa, prunus spp.) in response to waterlogging and submergence. these advances could provide opportunities to breed crops tolerant to oxygen deficiency. despite the advances in knowledge gained over the last years, some challenges need to be addressed: (i) the study of genes indicative of ethylene-mediated hypoxia acclimation must be deepened, exploring the universality of discovered mechanisms of tolerance across species; (ii) physiological traits associated with plant recovery from submergence and their regulation must be identified; and (iii) trait-to-gene-to-field approaches (i.e., “translational research”), warranting the development of strategies to cope with oxygen deficiency stress aiming to stabilize crop yields, must be promoted to resolve food insecurity in the future. the coordinated effort of research groups working at the different organization levels (e.g., molecular, plant and field) will increase the chances of success of the “translational research” as the main goal, implying the translation of basic scientific discovery into improved agricultural productivity. funding: this research received no external funding. acknowledgments: we would like to thank sylvia guo for the guidance and support throughout the entire process of this special issue. we also would like to thank the numerous reviewers and authors who contributed to this challenge with their science and expertise. conflicts of interest: the authors declare no conflict of interest. references . fao. damage and losses from climate-related disasters in agricultural sectors; food and agricultural organization of united states. retrieved from fao, i en/ / . . available online: http://www.fao.org/ /a-i e.pdf (accessed on december ). . pucciariello, c. molecular mechanisms supporting rice germination and coleoptile elongation 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vuttipongchaikij, s. overexpression of jatropha curcas erfvii transcription factor confers low oxygen tolerance in transgenic arabidopsis by modulating expression of metabolic enzymes and multiple stress-responsive genes. plants , , . . shukla, v.; lombardi, l.; pencik, a.; novak, o.; weits, d.a.; loreti, e.; perata, p.; giuntoli, b.; licausi, f. jasmonate signalling contributes to primary root inhibition upon oxygen deficiency in arabidopsis thaliana. plants , , . . voesenek, l.a.c.j.; sasidharan, r. ethylene–and oxygen signalling–drive plant survival during flooding. plant biol. , , – . . sasidharan, r.; voesenek, l.a.c.j. ethylene-mediated acclimations to flooding stress. plant physiol. , , – . . hartman, s.; van dongen, n.; renneberg, d.m.; welschen-evertman, r.a.; kociemba, j.; sasidharan, r.; voesenek, l.a.c.j. ethylene differentially modulates hypoxia responses and tolerance across solanum species. plants , , . . hong, c.p.; wang, m.c.; yang, c.y. nadph oxidase rbohd and 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on pisum sativum roots. plants , , . . salvatierra, a.; toro, g.; mateluna, p.; opazo, i.; ortiz, m.; pimentel, p. keep calm and survive: adaptation strategies to energy crisis in fruit trees under root hypoxia. plants , , . publisher’s note: mdpi stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). microsoft word - efficiencypaper .doc la-ur- - approved for public release; distribution is unlimited. title: assessing the efficiency of us electricity markets author(s): ismael arciniegas, chris barrett, and achla marathe submitted to: http://lib-www.lanl.gov/cgi-bin/getfile? .pdf los alamos national laboratory, an affirmative action/equal opportunity employer, is operated by the university of california for the u.s. department of energy under contract w- -eng- . by acceptance of this article, the publisher recognizes that the u.s. government retains a nonexclusive, royalty- free license to publish or reproduce the published form of this contribution, or to allow others to do so, for u.s. government purposes. los alamos national laboratory requests that the publisher identify this article as work performed under the auspices of the u.s. department of energy. los alamos national laboratory strongly supports academic freedom and a researcher's right to publish; as an institution, however, the laboratory does not endorse the viewpoint of a publication or guarantee its technical correctness. form ( / ) assessing the efficiency of us electricity markets ismael arciniegasa (ismaela@lanl.gov), chris barretta (barrett@lanl.gov), and achla maratheb,* (achla@lanl.gov) a los alamos national laboratory. basic and applied simulation science (d- ) b los alamos national laboratory. modeling, algorithms and informatics group (ccs- ) *corresponding author: phone: ( ) - , mail stop b . abstract the recent california’s energy crisis has raised doubts about the benefits of energy deregulation. while it is true that the california electricity market is in turmoil, other electricity markets like the pennsylvania-new jersey-maryland (pjm) are doing fine. this paper assesses the mark of efficiency reached by the electricity markets in california, new york, and pjm. it also compares the degree of efficiency across markets (forward vs. real time) and across time. in terms of market efficiency no significant differences between the california and pjm electricity markets were discovered in the year of california’s energy crisis ( ). this research suggests that differences in price behavior between these two markets during did not arise from differences in efficiency. according to our analysis and measure of efficiency, pjm and california electricity markets are more efficient than the new york market. also, as these markets become more mature over time, their efficiency goes up. we also found evidence that multi-settlement scheduling system leads to higher efficiency. . introduction the recent deregulation of the power industry in several parts of the united states has produced different results across states. california’s deregulation has been characterized by skyrocketing wholesale electricity prices and several utilities on the brink of bankruptcy. the new york electricity market has encountered up to % increase in the electricity bills. on the other hand, the pennsylvania – new jersey – maryland (pjm) electricity market is enjoying low energy prices. in fact, the users of this market have saved billion dollars on electricity bills. the turmoil in some of the electricity markets is casting a shadow of doubt on deregulation plans of other states. a better understanding of the real causes of the differences in performance across electricity markets in the us is needed to help resolve some of the important issues. market inefficiency, market power, inelastic demand, and constrained supply are often quoted as the main cause of the problems experienced by some of the electricity markets (see [ ]). the aim of this paper is to assess the mark of efficiency reached by the electricity markets in california, new york, and pjm and see if some of the differences in price dynamics in these markets could be explained by the difference in their level of market efficiency. to the best of our knowledge a comparative analysis of efficiency among california, new york, and pjm electricity markets is novel. for this study hourly prices of day-ahead and real-time markets for each of the three power markets are collected. the price data was taken from the independent system operator’s website of each market and from the university of california energy institute (ucei) . some of the hourly price series were available by load zone and not per market. in those cases an aggregation was done using load-weighted averages. given the data availability, a selected group the websites from which the data was retrieved were: www.nyiso.com, www.pjm.com, www.caiso.com, www.ucei.berkeley.edu/ucei. of years was analyzed for each market: california ( - ), pjm ( - ), and new york ( - ). the results indicate that efficiency has risen with the maturity of the markets. interestingly, this research did not find significant differences in efficiency between the california and pjm power markets during the year of the california’s energy crisis ( ). the new york electricity market was found to be the least efficient among the three. . comparison of california, pjm and new york electricity markets this study analyzes the price dynamics of the power markets in california, pjm, and new york and compares the level of efficiency reached by each one of these markets. a market is efficient when all the relevant and ascertainable information is fully and immediately reflected in market prices. in an efficient market all players are well-informed and adjust their market strategies continuously to take advantages of the arbitrage opportunities. an arbitrage opportunity exists if it is possible to design a strategy that can yield risk less economic profits (see [ ] for details). there is plenty of literature that describes the functioning of california, pjm, and new york electricity markets (see [ ], [ ], [ ], and [ ]). a review of that literature points out important differences in market structure across states which may explain differences in market efficiency. some of these differences are discussed below: • 	 maturity of the market: as the market matures, players accumulate more experience which allows them to be better prepared to take advantage of the arbitrage opportunities. removal of these arbitrage opportunities leads to higher market efficiency. hence differences in “maturity” between markets may be relevant in explaining differences in efficiency across markets. california was the first us state to restructure its electricity market which started at the beginning of . pjm which is the oldest centralized dispatched network in the world started its restructuring at the beginning of . new york’s deregulated electricity market also started operation in although it was later than california . • 	 multi-settlement vs single-settlement scheduling systems: in the scheduling process two alternatives are available: multi-settlement and single-settlement system. under a multi- settlement system implies the prices and quantities established in market phases prior to dispatch are binding forward contracts. the spot-market (run by the iso) is used to settle any difference between the scheduled transactions and the actual transactions. in a single- settlement system the forward phase is used just for scheduling purpose, all transactions are settled at the spot market price (see [ ] for additional details). california runs a multi-settlement system with day-ahead and hour-ahead phases prior to dispatch. in california, the day-ahead transactions are binding and settled at the day-ahead price. similarly, the hour-ahead transactions are settled at the hour-ahead prices. until may , pjm ran a single-settlement system. on june , pjm switched to a multi-settlement system that is similar to the california’s system. the ny electricity market has day-ahead and hour-ahead phases as well as a real-time one. like in california these markets work in a multi-settlement system, where the transactions in the forward market (day and hour-ahead) are traded at the forward price. the balance between the real-time transactions and the scheduled ones is traded at the real-time price. the multi and single-settlement systems have potential advantages and disadvantages which may have an impact on market efficiency. a multi-settlement system may increase the opportunities for arbitrage by running a binding day-ahead information obtained from the energy information administration www.eia.doe.gov market which is repeated on an hour-ahead basis. it also reduces risk by providing price certainty to the generators before the actual dispatch (see [ ]). on the other hand, a single-settlement system may lead to productive efficiency gains by lowering the transactions costs that a sequence of forward markets may produce. • 	 competing forward markets: [ ] argues that having competitive forward markets which can trade with one another may reduce the arbitrage opportunities existing in the electricity markets by increasing the competitive discipline in the forward markets. thus, differences in the organization of the forward markets across states may explain differences in market efficiency. in california, competing scheduling coordinators (scs) run the forward markets. the independent system operator (iso) runs the transmission, ancillary and real-time markets. among the scs, the power exchange (px) used to handle most of the trading in the california forward markets . the px ran auctions to establish energy prices and schedules for both the day-ahead and hour-ahead market. on the other hand, the automated power exchange which is also an sc, runs a continuous forward market. the others scs in california work through bilateral contracts to tailor consumers’ needs. the energy prices in the different scs converge as trading among scs is permitted. in pjm the participants can implement the day-ahead phase either by submitting bids to a centralized dispatch managed by the iso or by decentralized bilateral schedules. unlike california, pjm has just one centralized day-ahead dispatch which is administrated by the iso. in the iso-run day-ahead market, generators’ offers must specify the prices and the ranges of output over which these prices apply. in the bilateral scheduling, participants indicate the amount of energy injected and withdrawn from each the px filed for bankruptcy at the beginning of . location in each hour of the following day. the iso uses the bids of the centralized day- ahead market to run an optimization program. this determines the minimum cost order of dispatch that meets the forecasted load that is not going to be supplied by the bilateral arrangements in the next day. the results from the optimization program tell all the market participants the likelihood of selling or buying power over the next day. see [ ] for more information. like in pjm, there are no competing centralized forward markets in new york. the centralized day-ahead dispatch is managed by the iso which receives the bids from the market participants and produces a load forecasts for all hours of the following day. iso runs an optimization program with the load forecast and the bids to determine the mix of generation for the next day that minimizes the production costs over the day while observing the constraints on the transmission system. the optimization program also computes the day-ahead market price. the iso-run day-ahead markets of pjm and new york are subject to the competitive discipline of the bilateral markets . however, an iso can use its power as grid manager to favor its day-ahead market undermining the fairness of the market and therefore its efficiency. • 	 long-tem markets: as suggested by [ ] the existence of many forums for trading over time (long-term, day-ahead, hour-ahead) encourages generators to compete more aggressively in the spot market as they have sold significant portions of their output in the forward markets. more aggressive competition should lead to faster learning and more efficiency. as any player can choose between submitting bids to the iso-run day ahead market and bilateral market. till recently, california utilities were not allowed to get into long term contracts and more than % of the power was purchased in the spot market. instead in pjm, utilities could lock in prices through long term contracts. therefore only to % of the power was bought in the spot market. due to the higher flexibility available in pjm to meet its long term energy needs, the prices were less volatile in pjm as compared to california. • 	 ancillary services (as): as a generator has to decide how to bid in each market, a shock in the as market is going to be reflected in the forward and spot markets. as noted by [ ] the structure of as market greatly complicates a generator’s choice in bidding in the electricity markets. more bidding choices for a generator decrease its ability to find potentially riskless strategies. in pjm just operating reserves and regulation are traded. pjm assigns duties in providing regulation to all generators. if a generator can not provide regulation, it must meet its obligation by writing bilateral contracts. till may , pjm used a cost based market for procuring regulation but in june , pjm started procuring regulation using market prices. in california the as markets allocate: regulation, spinning reserves, non-spinning reserves, and replacement reserves . in california’s electricity market, as are allocated using day-ahead and hour-ahead markets. for the day-ahead as market, a generator submits bids in which it specifies the total capacity that the iso can use for any of the four services (regulation, spinning reserves, non-spinning reserves and replacement reserves) and the energy price (uniform for all services). each hour the iso examines the regulation refers to the services provided by generators to maintain a hz operating level in the transmission network. the types of reserves differ by the amount of time the generator has before it must begin supplying power to the grid and whether or not the facility must be synchronized to the grid while waiting in reserve. system and determines the amount of as it requires. the iso resolves each market in sequence starting with regulation first and ending with reserve replacement. if a generators was not selected in the first as it can still participate in the next as market. the as hour-ahead market operates similar to the as day-ahead market. unlike pjm, in california the generators do not bid in each one of the as markets independently. in new york, each one of the six as is traded independently in the market. suppliers receive payments according to the quantities supplied and the market clearing prices in the day-ahead and supplemental markets. • 	 fuel mix : the volatility of the fuel prices varies depending upon the fuel. volatility in fuel price causes volatility in the electricity prices because fuels are a major component of generators’ costs. therefore, a diversified fuel source may prevent excess of volatility in the electricity prices. the lower volatility may lead to fewer arbitrage opportunities and more efficient and stable market. in california most of the energy is provided by gas-fired ( %) and hydro ( %) generators. in contrast, pjm fuel mix is more diverse including coal, and nuclear. like pjm, the fuel mix in new york is also more diverse than in california. ny electricity market uses gas ( . %), hydroelectric ( %) and nuclear ( %). . market efficiency . . related work our approach to studying market efficiency in power markets is similar to previous empirical literature that focused on the price dynamics of power markets around the world. in [ , ], the authors analyze the price dynamics of interconnected regional markets in the data is provided by the energy information administration western us between - for evidence of market integration. their results show that markets were efficient and stable in that region. [ ] compares the degree of competition between the electricity markets of england, wales, norway, and australia. it concludes that the differences in the degree of competition level across international electricity markets can be explained by the differences in market design. [ ] discusses the complex decisions faced by the generators in deciding how much to trade in the different california electricity markets (e.g. day- ahead market, spot market, ancillary market, etc). it argues that rational behavior leads generators to continuously adjust their strategies to take advantage of the arbitrage opportunities across markets. [ ] examines the evolution of the competitive electricity markets in california and pjm. it also proposes regulatory modifications that may make these two markets more competitive. [ ] analyzes the advantages and disadvantages of binding and non-binding day- ahead markets. [ ] evaluates the level of market integration between the california day-ahead market and the real-time market. it concluded that the price convergence between these two markets increased as time passed. this research contributes to previous empirical literature by evaluating the efficiency of the three major power markets in us (california, pjm, and new york). it computes a measure of market efficiency for each market for each of the years analyzed. it also compares the efficiency across different time markets and across states. . . the model market efficiency can be evaluated by the “predictability” of changes in the price. in an efficient market, one should not be able to make abnormal economic profits using readily available information. the current price should reflect all the relevant and ascertainable information. predictable prices imply that generators could use readily available information to design strategies that yield abnormal profits. this study performs two tests: first evaluates the “predictability” of a price series by testing its “stationarity”. a series yt is said to follow a stationary process if its mean, variance and autocorrelation are independent of time, implying that one could calculate the future values of a series using its current values. two, it looks for arbitrage opportunities by checking if the expected return in the forward and the real markets are the same using cointegration analysis. two series are cointegrated if they have a common trend and change roughly at the same rate. if the day-ahead and the real-time markets are cointegrated, a shock in the former will also be reflected in the latter and the expected return in both markets will be the same. this would imply that generators can not play across markets to increase their profits. from the definition of an efficient market it should be clear that the price series of an efficient market can not be stationary. otherwise, it would be possible to use the past information to predict the future changes in prices and make abnormal profits. also, the forward and real- time prices should be cointegrated for the market to be efficient, otherwise the difference in expected returns would create arbitrage opportunities and cause inefficiency. to test the stationarity of a series, we check for the presence of a unit root in the price series using the augmented dickey-fuller (adf) test [ ]. the adf test requires the estimation of the following regression equation: tlt l l ltt eppp +∆++=∆ −=− ∑ ββα ( ) where: ∆p = change in the electricity price α, β , β = coefficients pt- = electricity price in period t- et = residuals the null hypothesis of this test is β = . the number of lags in equation ( ) was determined by initially estimating a general model with lags and then in successive estimations the insignificant lags were dropped. this procedure makes sure that the results of the adf test are not misleading and the residuals in ( ) are uncorrelated. as was mentioned in the earlier discussion of market efficiency, the expected return in the day-ahead and real-time markets for the same hour should grow at the same rate. note, that both markets trade the same commodity. if the expected return in one market is more than the other, there would be an opportunity to make risk less profit and the market would be inefficient. in time series analysis, if two series track one another and grow roughly at the same rate, they are said to be cointegrated. by definition, cointegration necessitates that the two series be integrated of the same order and have a common trend. the order of integration is the number of times a non-stationary series has to be differentiated to obtain a stationary series. two series with different order of integration cannot be cointegrated. an important consequence of cointegration is that it is possible to find a linear combination of the cointegrated series that generates a stationary series. this property is used in testing for cointegration. the following cointegration relation was tested here: hhrhd pp εβα ++= ,, * ( ) where: pd,h = price of the day-ahead market at hour h pr,h = price of the real-time market at hour h α,β = parameters of the cointegration vector εh = error this paper uses the johansen test to determine the cointegration between the day-ahead and real-time market for each hour. the application of the johansen test requires the estimation of a vector autoregressive model (var) of the form: ktktkttt pppp −−−− +Γ++Γ+Γ+Γ= ε... ( ) where pt = column vector with the day-ahead and real-time prices Γi = matrix of parameters ε. =disturbance the number of lags in the estimated var model was determined using the schwarz information criterium (see [ ]). under cointegration the matrices of parameters in ( ) should be short ranked. the johansen test uses this property to test for cointegration. see [ ] for details. based on the results of the unit roots and cointegration tests, a measure of efficiency for each year and state market was constructed in the following way: * , , ji ji ch e = ( ) where: ei,j = efficiency of market i. in year j. chi,j = number of cointegrated hours of market i. in year j. . results and discussion table shows the unit root test results for each hour in a year, in california, pjm, and new york. from table it can be observed that in all the three states, some hours were stationary. in california the number of stationary hours rose between and but then dropped in in both the day-ahead and real-time markets. the increase in inefficiency between and could have been due to the significantly higher wholesale prices and artificially set price caps. these price caps had not been triggered in . for pjm, the real-time market was very inefficient in ( % of the real-time market hours were stationary). the number of stationary real-time market hours dropped significantly in and . this could be due to the fact that pjm switched to multi-settlement system in from a single-settlement system. in a multi-settlement system the forward commitments are binding and most of the trading occurs in the forward markets. the real-time market was quite inefficient in n.y ( % of the real-time market hours were stationary) during and . however, the day-ahead market was efficient in more than % of the hours. this difference in efficiency between the two markets may be explained by the fact that most of the volume is traded in the forward markets. the real time market only operates like an imbalance market with very little volume compared to the forward markets. when the market has few players, low volume, lack of information flow due to time constraints, it is likely to be more inefficient. table shows the efficiency results as measured by the cointegration tests. in california the forward and real time markets were cointegrated % of the hours in which increased to % in . this improvement may be explained by a “learning by doing” process as players learn from their past experience and exploit all the arbitrage opportunities available in the market, ultimately making the market more efficient. in pjm, there was no significant change in the number of cointegrated hours between and . comparing california and pjm in year , it is noteworthy that california was slightly more efficient than pjm. in fact california had the highest level of efficiency among the three markets. in new york the market efficiency measure stayed at % in and . the lack of “learning” in new york between and may be explained by the existence of barriers and transaction costs that stopped traders from taking advantage of the arbitrage opportunities or by high levels of risk aversion among players (see [ ]). in the electricity prices in california and new york skyrocketed, whereas in pjm they remained stable. interestingly, in there was no difference in market efficiency between california and pjm, suggesting that the differences in price behavior between these two markets were not due to market efficiency. thus, other potential explanations (e.g. market power, supply constraints) should be explored to understand the differences in price dynamics between california and pjm power markets in . on the other hand, new york market was significantly more inefficient than pjm in and . perhaps, market efficiency could explain differences in price behavior between pjm and new york. an efficiency ranking of the three state electricity market renders california as the most efficient and new york as the least efficient for year . . conclusions this paper evaluates the efficiency of the power markets in california, pjm, and new york for the past few years. several conclusions can be derived from our results. first, in both california and pjm, the efficiency of the power markets has improved with the maturity of the markets. second, multi-settlement scheduling system seems to be associated with higher market efficiency. third, contrary to the common belief, in the california market appears to be as efficient as the pjm market based on our measure. thus, the differences in price dynamics between these two markets can not be explained by the differences in efficiency. however, an efficiency argument may be made to explain differences in prices between ny and pjm in that year. . further research further research on the following topics could be explored: first, a cointegration analysis between the ancillary services markets, the forward, and the spot markets could be implemented using the same methodology discussed here. second, a cointegration analysis could also be implemented in testing for price convergence across the different scheduling coordinators in california. finally, other potential explanations that clarify the difference in price behavior of different markets could be explored more rigorously. references [ ] borenstein, s. . the trouble with electricity markets (and some solutions). university of california. energy institute. pwp- . 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[ ] johansen, s., . estimation and hypothesis testing of cointegration vectors in gaussian vector autoregressive models. econometrica. , - . hours real day-ahead real day-ahead real day-ahead real day-ahead real day-ahead real day-ahead real day-ahead - . * - . - . - . - . - . - . na - . . - . - . *- . * - . - . - . - . - . - . - . - . na - . . - . - . *- . * - . - . - . - . - . - . - . - . na - . . - . - . - . - . - . - . - . - . - . - . - . na - . . - . - . - . * - . - . - . - . - . - . - . . na . . - . - . - . - . - . - . - . - . - . - . - . * na - . . - . * - . - . - . - . - . - . - . - . - . - . * na - . . - . - . - . - . - . - . - . - . - . - . - . * na - . . - . - . - . - . - . - . - . - . * - . - . - . * na - . - . - . - . - . - . - . - . - . - . - . - . - . na - . - . - . - . - . - . - . - . - . - . - . - . - . * na - . - . - . - . - . * - . - . - . - . - . - . - . - . * na - . * - . *- . * - . - . - . - . - . - . - . - . - . - . * na - . * - . * - . - . - . - . - . - . - . * - . - . * - . - . na - . * - . * - . - . - . * - . * - . - . - . * - . - . * - . - . * na - . - . - . . - . - . - . - . - . * - . - . - . - . * na - . - . - . . - . * - . - . - . - . * - . - . - . - . * na - . - . * - . - . - . * - . - . - . *- . * - . * - . - . - . * na - . - . - . - . - . - . - . - . * - . - . * - . - . - . * na - . . - . - . - . * - . - . - . * - . - . * - . - . - . * na - . . - . - . - . - . - . - . *- . * - . * - . - . - . * na - . - . - . - . - . * - . - . - . - . - . - . - . - . * na - . - . - . - . - . * - . - . - . - . - . - . - . - . * na - . - . - . - . - . * - . - . - . - . - . - . - . - . * na - . . - . * - . - . * - . stationary na hours * rejects of the hull hypothesis of unit root at % level n/a. in pjm used a single settlement system, meaning that all setlements are based on spot market prices. table . unit roots augmented dickey fuller test n.y pjm california table . johansen cointegration tests h o u r x . . . * x x . . * . . . x x . . * . . . . . . . . . . . x x . . . . . . . . . . . x . . . * . . * . . . . . . . * . . * . . . x . . . . . . x . . . . x . . . . . x . . . . x x x . x x . . . x x . . x . x x x x . x x . . x x . . . x . x . . . x x . x . x . x . x x x . . . . x x x . . . x x x x . . . . x x x . . . x . . . . . x x x x . . . . . x x . * . . . x x x i n t e g r a t e d h o u r - m a r k e t s e f f i c i e n c y ( % ) * c o in t e g r a t io n h y p o t h e s is r e j e c t e d a t % le v e l x s t a t io n a r it y in e ih e r d a y - a h e a d o r r e a l- t im e m a r k e t s x x s t a t io n a r it y in b o t h d a y - a h e a d a n d r e a l- t im e m a r k e t s c a l i f o r n i a p j m n . y 	assessing the efficiency of us electricity markets 	abstract 	introduction 	comparison of california, pjm and new york electricity markets 	market efficiency 	related work 	the model 	results and discussion 	conclusions 	further research 	references 		 - - t : : - 	mona l. mosier / aim ( ) superficial dry needling and active stretching in the treatment of myofascial pain – a randomised controlled trial janet edwards, nicola knowles introduction myofascial trigger points (trps) are a common source of musculoskeletal pain presenting in primary care. general practitioners frequently refer these patients to physiotherapy departments for treatment. identifying trps requires training and clinical expertise. ; whilst british undergraduate medical and physiotherapy training does not include trp identification, substantial literature ; and postgraduate training are available. despite this there is evidence that trps causing musculoskeletal pain often go undiagnosed by both doctors and physiotherapists, leading to chronic conditions. - trps commonly arise from muscle overload, either as a result of acute strain/trauma, or of a more prolonged nature due to habitual postures or repetitive activities placing abnormal stresses on specific muscle groups. it is thought that if normal healing does not occur, sensitisation of peripheral nociceptors by endogenous substances becomes prolonged, leading to increased local tenderness and referred pain. sensitisation also takes place at spinal level, where receptive fields in the dorsal horn extend and become sensitive to lesser stimuli. one hypothesis suggests that trps develop at motor end plates, where sensitisation of sensory and autonomic nerve endings leads to janet edwards physiotherapist lancaster, uk nicola knowles senior lecturer school of health and social science coventry university, uk correspondence: janet edwards janetedwards_physio @yahoo.co.uk summary a pragmatic, single blind, randomised, controlled trial was conducted to test the hypothesis that superficial dry needling (sdn) together with active stretching is more effective than stretching alone, or no treatment, in deactivating trigger points (trps) and reducing myofascial pain. forty patients with musculoskeletal pain, referred by gps for physiotherapy, fulfilled inclusion / exclusion criteria for active trps. subjects were randomised into three groups: group (n= ) received superficial dry needling (sdn) and active stretching exercises (g ); group (n= ) received stretching exercises alone (g ); and group (n= ) were no treatment controls (g ). during the three-week intervention period for g and g , the number of treatments varied according to the severity of the condition and subject/clinician availability. assessment was carried out pre-intervention (m ), post- intervention (m ), and at a three-week follow up (m ). outcome measures were the short form mcgill pain questionnaire (sfmpq) and pressure pain threshold (ppt) of the primary trp, using a fischer algometer. ninety-one per cent of assessments were blind to grouping. at m there were no significant inter-group differences, but at m , g demonstrated significantly improved sfmpq versus g (p= . ) and significantly improved ppt versus g (p= . ). there were no differences between g and g . the mean ppt and sfmpq scores correlated significantly in g only, though no significant inter-group differences were demonstrated. numbers of patients requiring further treatment following the trial were: (g ); (g ); (g ). conclusion: sdn followed by active stretching is more effective than stretching alone in deactivating trps (reducing their sensitivity to pressure), and more effective than no treatment in reducing subjective pain. stretching without prior deactivation may increase trp sensitivity. keywords myofascial trigger point; myofascial pain; acupuncture; superficial dry needling, active stretching exercise; randomised controlled trial. papers acupuncture in medicine ; ( ): - . www.medical-acupuncture.co.uk/aimintro.htm / aim ( ) / / : pm page group.bmj.com on july , - published by aim.bmj.comdownloaded from mailto:janetedwards_physio@yahoo.co.uk http://www.medical-acupuncture.co.uk/aimintro.htm http://aim.bmj.com/ http://group.bmj.com/ papers acupuncture in medicine ; ( ): - . www.medical-acupuncture.co.uk/aimintro.htm excessive release of acetylcholine, preventing normal functioning of the calcium pump mechanism, resulting in sustained contraction of sarcomeres. the contracted muscle f ibres compress blood vessels, causing local hypoxia. an energy crisis ensues as the increased energy demand from sustained contraction cannot be met because of local hypoxia. whilst universally accepted classif ication criteria have yet to be established, active trps are typified by tender spots in taut muscular bands, pressure on which reproduces the patient’s pain in typical patterns for each trp. local twitch responses (ltrs) may be elicited by snapping palpation. spontaneous electrical activity (sea) has been identified at minute loci of trps. - macdonald found that both active and passive stretching of muscles containing trps, increased pain, whereas movements in which muscles worked as the agonist (isotonically) did not. if resistance was applied to the muscle (isometric contraction) pain was again increased. trp deactivation is a term introduced by baldry to describe the process whereby an active trp becomes inactive i.e. local tenderness on palpation is resolved and the taut muscular band released, with ensuing symptomatic pain relief. various methods are used to deactivate trps, including ultrasound, - pressure release, ; cold spray and stretch and injection of local anaesthetic. dry needling (no substance injected) may be carried out either superficially (sdn) or with deeper insertion (ddn). ; much discussion has ensued on the merits of ddn and sdn, though research evidence on the latter is limited. an earlier study using sdn (to a depth of mm) on trps causing chronic low back pain, showed significant benefits for this method. however study numbers were relatively small ( sdn, placebo tens) and since electroacupuncture was introduced if no improvement was gained from sdn, it is impossible to assess the precise effects of needling. a recent rct comparing the two methods demonstrated ddn to be signif icantly superior to sdn in reducing shoulder myofascial pain. this study combined traditional acupuncture points with trps, using needles at each of eight sessions, therefore its conclusions may not equate with individual trp needling. a review of studies of needling therapies for myofascial pain (mostly ddn) concluded that since no method demonstrated superiority, patient comfort should be a main consideration. baldry claims minimal patient discomfort during years’ successful practice using sdn at - mm depth. in common with baldry, one author (je) experiences notable success in clinical practice in deactivating trps by sdn, needling to a depth of mm. it has been suggested that as the needle pierces the skin, a-delta nerve fibres are activated, resulting in inhibition of muscular c-fibres conveying pain from the trp. subsequent relaxation of the trp’s taut muscular band enables the energy crisis at the motor end plate to resolve. restoring the affected muscle to its full range of movement following trp deactivation is an essential part of recovery, with three slow active stretches being recommended. ; with preceding factors in mind a pragmatic, randomised, single blind controlled trial was carried out to test the hypothesis that sdn together with active stretching is more effective than stretching alone, or no treatment, in deactivating trps and reducing myofascial pain. methods the study took place during the five month period from july to dec . following local research ethics committee approval, subjects were recruited from patients with musculoskeletal pain, referred for physiotherapy by five gps at an inner city lancaster practice. a small pilot study of one subject per group preceded the trial. this was useful for the clinicians to standardise algometry techniques and test worthiness of forms for recording measurements, to which minor adjustments were made. inclusion criteria were: aged and over; presence of active trp identif iable by a) spot tenderness in a taut muscular band, b) subject recognition of pain on palpation, c) painful limitation of affected muscle’s full range of movement, d) ltr, e) pain in expected distribution (a, b, c essential to inclusion; d and e not essential but used to confirm diagnosis); patient agrees not to receive additional treatment for their painful condition during the trial (apart from nsaids and pain / aim ( ) / / : pm page group.bmj.com on july , - published by aim.bmj.comdownloaded from http://www.medical-acupuncture.co.uk/aimintro.htm http://aim.bmj.com/ http://group.bmj.com/ killers); patient is capable of complying with the trial. exclusion criteria were: acute condition requiring treatment before six weeks; skin lesion, infection or inflammatory oedema at trp site; needle phobia; previous adverse reaction to acupuncture or anaesthetic; serious neurological or systemic disorder. subjects were randomised into three groups by selection of numbers to in sealed brown envelopes, when a witness was always present. fourteen subjects were randomised into group (g ) to receive superficial needling and active stretching exercise, subjects to group (g ) for stretching exercise, and into group (g ) who were no treatment controls. clinical assessment subjects were given a full musculoskeletal physiotherapy assessment by je, an experienced senior physiotherapist with training in trp identification and a further two years’ clinical experience. trps relevant to the patient’s pain complaint were identif ied by palpation and marked on a body chart, recording precise measurements from bony landmarks if difficulties in ongoing identification were anticipated. a maximum of six trps relevant to the condition were included. in je’s experience this number is treatable in one session and allows for inclusion of satellite trps. the trp most closely reproducing the patient’s pain on palpation was measured for study purposes. interventions interventions were carried out by je in the physiotherapy department attached to the practice. group patients received a course of sdn to affected trps, followed by appropriate stretching exercises to be continued at home. exercises used were those recommended by simons et al. ; trps implicated in the condition were palpated and marked with a small dot on the skin at each treatment session, then needled in turn, usually working from proximal to distal. sterile stainless steel acupuncture needles ( x . mm) with coiled copper handles and plastic guide tubes were used (helio medical supplies, inc.). the needle was inserted to the depth allowed by the guide tube ( mm). if not secured into the skin, further gentle pressure was applied, fractionally increasing penetration. the needle was not manipulated or stimulated and was left in situ until any sensations experienced by the patient, following needle insertion, had subsided. the duration of needle retention was recorded. the number of attendances over the three week treatment depended on the severity of condition and patient / therapist convenience, as is normal physiotherapy practice. group patients received instruction in appropriate stretching exercises, as recommended by simons et al, for involved muscle(s) containing trps. ; as with g patients they were asked to carry out home exercises, repeating three stretches three times daily. the importance of relaxing muscles between stretches was stressed. follow up appointments were made to check / alter exercises according to the condition. groups and both groups were advised on correction of daytime or sleeping postures if contributing to trp activation. following the three weeks’ intervention, both groups had no treatment for three weeks, but continued with home regimes. group patients randomised to g received no treatment over the six week study period. outcomes outcome measures were the short form mcgill pain questionnaire (sfmpq) and pressure pain threshold (ppt). the sfmpq included a visual analogue scale (vas), pain descriptors, and a to present pain intensity scale, together giving a total pain score. ppt of the primary trp was measured in kg/cm , using a fischer algometer (pain diagnostics and thermography, new york). the trp was identified by je and marked on the skin with a small pen mark. with the patient comfortably supported and relaxed the algometer was applied directly over the trp, perpendicular to the body surface. pressure was applied at the rate of kg/s and the patient was instructed to say ‘now’ when the feeling of pressure turned to pain. three readings were taken, allowing to seconds between each, papers acupuncture in medicine ; ( ): - . www.medical-acupuncture.co.uk/aimintro.htm / aim ( ) / / : pm page group.bmj.com on july , - published by aim.bmj.comdownloaded from http://www.medical-acupuncture.co.uk/aimintro.htm http://aim.bmj.com/ http://group.bmj.com/ papers acupuncture in medicine ; ( ): - . www.medical-acupuncture.co.uk/aimintro.htm the average being the final score. measurement took place at m , pre-intervention; m , after three weeks of the interventions in g and g , or three weeks with no treatment in g ; and m after a follow-up period of a further three weeks. measurements were carried out blind by two trained observers, the surgery’s health care assistant and a research assistant employed by morecambe bay pct. both received prior training in use of the algometer. on some occasions neither assistant was available. this necessitated one of the authors (je) taking % of measurements. as the pre-treatment m measures were still blind to grouping, % of measures were not blinded. at the end of the trial patients were asked if they required further treatment or physiotherapy for their condition. data analysis data was analysed using spss windows / programmes. baseline characteristics of age, gender, pain duration, number and site of trps, were analysed using chi square or anova tests to detect any differences between groups. sfmpq and ppt data were examined visually and found to be reasonably normally distributed. analysis was therefore carried out using parametric anova and where this indicated significant overall difference (p≥ . ) two sample t-tests were performed. ninety five percent confidence intervals were compared for mean outcome per group and used to perform significance tests at the % level of significance. pearson’s correlation coefficients between change in ppt and sfmpq between m and m were calculated. table group baseline characteristics, mean and (standard deviation). needling and stretch stretch untreated controls g g g n female % % % % age ( ) ( ) ( ) pain duration in months ( ) ( ) ( ) no of trps involved . ( . ) . ( . ) . ( . ) upper body trps % % % % table mean sfmpq and ppt scores at m , m and m . needling and stretch stretch untreated controls g g g m m m m m m m m m sfmpq mean . . . . . . . . . (sd) ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) ppt mean . . . . . . . . . (sd) ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) table mean sfmpq and ppt change scores at m and m with p values for inter group comparisons. needling and stretch stretch untreated controls g g g m -m m -m m -m m -m m -m m -m sfmpq mean - . - . - . - . - . - . (sd) ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) p< . vs. g p< . vs. g ppt mean + . + . + . + . + . + . (sd) ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) p< . vs. g p< . vs. g two sample t-tests were performed where anova indicated a significant overall difference, p values are p> . unless otherwise indicated. / aim ( ) / / : pm page group.bmj.com on july , - published by aim.bmj.comdownloaded from http://www.medical-acupuncture.co.uk/aimintro.htm http://aim.bmj.com/ http://group.bmj.com/ results sixty-six patients were assessed for trps. of these fulfilled the inclusion criteria and agreed to take part in the study. all patients completed the trial. a total of needle insertions were carried out on g patients. the average number per session was . (max . , min . ). the needles were retained for an average of . minutes (max . , min . ), this time corresponded to the duration of sensations experienced by the patient. sixteen needles ( %) failed to produce any sensation. baseline characteristics (table ) showed no significant differences between groups. sfmpq and ppt means at m , m and m are shown in table . mean change scores at m and m , with inter-group comparisons (table ), indicate no significant differences at m . however, at m , g was significantly different compared to g in sfmpq scores (p= . ), and compared to g in ppt scores (p= . ). ppt and sfmpq scores correlated significantly (in the expected direction) only in g , though no significant difference in correlation coefficients was found between the groups. the mean number of treatment sessions was lower for g ( . ) than for g ( . ) (table ). the number of patients requiring further treatment following the trial was considerably lower in g (table ). no side effects following trp needling were reported by patients, or observed by the therapist. there were no dropouts from the study. discussion studies assessing methods of trp deactivation are often single interventions on one trp, considering only immediate effects. ; ; ; ; it is accepted that several trps are commonly affected and may require a course of treatment. although only the primary trp was measured by algometry, the present study delivered a course of treatment to up to six affected trps, over a three week period, allowing a further three weeks for follow up assessment. all patients completed the trial, which may be due to its pragmatic approach and assurance of physiotherapy on completion if required. sixty per cent of patients examined for the trial presented with myofascial pain caused by active trps. prior gp screening for non-musculoskeletal pain in the present study, could account for lower figures ( %) in skootsky et al’s study, which examined patients presenting with pain of consecutive patients at a primary care centre. other baseline data compare favourably with skootsky et al, indicating a representative sample. the study’s findings demonstrate no significant differences between groups after three weeks of treatment (m ), but after a further three weeks follow-up (m ) g showed significantly improved sfmpq scores compared to g and significantly improved ppt scores compared to g . this would seem to indicate that in the three week period following treatment, g patients continued to improve compared to patients in g and g . mean scores for sfmpq and ppt (table ) highlight this f inding, particularly ppt scores, showing no improvement between m and m for g and g . it can be seen that g patients showed less improvement overall in ppt, than the controls (table ), and considerably more patients in g required treatment at the end of the trial (table ). this may suggest that stretching alone has adverse effects on trp sensitivity, supporting macdonald’s findings that stretching muscles containing trps is more likely to produce pain than when muscles contract isotonically as prime movers. ppt was not measured in macdonald’s study. correlations between sfmpq and ppt changes (m to m ) may also indicate that stretching without prior sdn increases trp sensitivity. only in g did the changes correlate significantly in the expected direction (i.e. a decrease in sfmpq correlated with an increase in ppt). g scores showed least correlation (table ). however, no significant difference in correlation coefficients was demonstrated between groups. interestingly, jaeger and reeves, treating upper trapezius and levator scapulae trps with spray and stretch, found papers acupuncture in medicine ; ( ): - . www.medical-acupuncture.co.uk/aimintro.htm table treatment sessions during trial and further treatment. g g g (n= ) (n= ) (n= ) mean number of treatment sessions during trial . . number of patients requiring treatment following trial / aim ( ) / / : pm page group.bmj.com on july , - published by aim.bmj.comdownloaded from http://www.medical-acupuncture.co.uk/aimintro.htm http://aim.bmj.com/ http://group.bmj.com/ papers acupuncture in medicine ; ( ): - . www.medical-acupuncture.co.uk/aimintro.htm no significant correlation between pain and ppt scores, suggesting this was due to non treatment of other affected trps. baseline characteristics affecting the trp sensitivity in g may be a higher incidence of upper body trps (table ), which have lower ppt scores than lower body trps, but this is not reflected in g scores at m (table ). average pain duration was lower for g than g or g (table ), which might be expected to correlate with a better outcome. ; although the treatment sessions in g were significantly fewer than in g (table ), which might be considered to result in reduced non- specif ic effects (therapeutic interaction and expectation), hopwood and abrams, analysing trp injections, found that a successful outcome did not correlate with the number of treatments. ppt threshold measurements in this study indicate that sdn is an effective method of deactivating trps. the study would appear to show that active trps require deactivation prior to stretching, with probable release of taut muscular bands and resolution of the energy crisis at motor end plates. stretching muscles without prior deactivation of the trp, may reduce subjective pain, but seems to have minimal effect on trp sensitivity or overall resolution of the condition, as demonstrated in g . although ppt scores improved more in g than g , this was not significant (p< . ), therefore no treatment was shown to be as effective as sdn and stretch in reducing trp sensitivity. however, since sdn with stretch was significantly more effective in reducing pain scores than no treatment, overall the study demonstrated greater benefits from sdn with stretch than either stretching alone or no treatment. this study indicates that significant numbers of patients with musculoskeletal pain referred by general practitioners to physiotherapy departments may suffer from myofascial trp pain. as trps are frequently located some distance from the pain, skill and training are required in order to detect them. sdn is a relatively quick and pain free method of trp deactivation. it is thought to work by needle prick stimulation of aδ fibres inhibiting of c fibre pain through descending mechanisms and dorsal horn interneurones. sdn inevitably causes less discomfort to recipients than ddn methods. ; there is also likely to be lower risk of traumatic side effects, particularly in anticoagulated patients. since patient safety and comfort should be prime considerations in choice of needling therapy for myofascial pain, sdn followed by active stretching is an appropriate treatment choice. physiotherapists and general practitioners practising acupuncture are well placed to deliver this treatment, which if provided in a primary care setting, may well help prevent the development of chronic pain and dysfunction. study limitations greater numbers and longer term follow up would have added weight to the study’s findings. as nine percent of measurements were not blind to grouping, it is possible that bias was introduced. however, every effort was made to maintain impartiality, and previous scores were concealed during measurements. in addition, if measures fell between two scale indices (sfmpq and ppt) the score in the opposite direction to expected bias was recorded. implications for research since this study used sdn together with stretch, more research is needed to evaluate the effectiveness of sdn alone, and sdn compared with sdn and stretch. also, the duration of trp needling warrants further research. conclusion this study supports the hypothesis that sdn followed by active stretching is more effective than stretching alone, or no treatment, in the management of myofascial pain caused by active trps. stretching alone, in some cases, may table analysis of sfmpq (m -m ) vs ppt (m -m ). g g g correlation coefficient - . - . - . % confidence interval - . to . - . to + . - . to + . p value . . . no significant difference in slopes (p= . ). / aim ( ) / / : pm page group.bmj.com on july , - published by aim.bmj.comdownloaded from http://www.medical-acupuncture.co.uk/aimintro.htm http://aim.bmj.com/ http://group.bmj.com/ increase trp sensitivity, leading to delayed resolution. acknowledgements the authors wish to thank chris wright, school of health and social sciences, coventry university and sally hollis, medical statistics unit, lancaster university, for guidance on statistical analysis, and bob charman for his comments on the article. reference list . skootsky sa, jaeger b, oye rk. prevalence of myofascial pain in general internal medicine practice. west j med ; ( ): - . . gerwin rd, shannon s, hong cz, hubbard d, gevirtz r. interrater reliability in myofascial trigger point examination. pain ; ( - ): - . . hsieh cy, hong cz, 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using social cognition and persuasion to promote energy conservation: a quasi‐experiment | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /j. - . .tb .x corpus id: using social cognition and persuasion to promote energy conservation: a quasi‐experiment @article{gonzales usingsc, title={using social cognition and persuasion to promote energy conservation: a quasi‐experiment}, author={m. gonzales and e. aronson and m. costanzo}, journal={journal of applied social psychology}, year={ }, volume={ }, pages={ - } } 	m. gonzales, e. aronson, m. costanzo 	published 	psychology 	journal of applied social psychology a quasi-experiment was conducted to determine if the effectiveness of the r.c.s. home energy audit program could be improved by training auditors to use social-psychological principles during the audit procedure. nine experienced home energy auditors attended two -day workshops in which they were trained to: (a) communicate vividly; (b) personalize their recommendations to homeowners; (c) induce commitment; and (d) frame their recommendations in terms of “loss” rather than “gain”. the… expand view via publisher markcostanzocom.ipage.com save to library create alert cite launch research feed share this paper citationshighly influential citations background citations methods citations results citations view all tables from this paper 	 table 	 table paper mentions news article why you click on negatively titled articles instead of positive ones medium us may citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency a review of intervention studies aimed at household energy conservation 	w. abrahamse, l. steg, c. vlek, t. 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	view excerpt, references background save alert research feed the hawthorne experiments: first statistical interpretation. 	r. h. franke, j. kaul 	sociology 	 	 save alert research feed energy conservation research of california's utilities 	l. white, d. archer, + authors s. yates 	psychology 	 	 	view excerpt, references methods save alert research feed insensitivity to sample bias: generalizing from atypical cases 	r. hamill, t. wilson, r. nisbett 	psychology 	 	 	pdf save alert research feed ... ... related papers 	abstract 	tables 	paper mentions 	 citations 	 references 	related papers stay connected with semantic scholar sign up about semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue tms: a link to our past; a bridge to our future i, like many, view tms as my home society and going to the tms annual meeting as a kind of professional family reunion, where we share a materials bond, interactions occur across generations, and it is hard to move without bumping into old friends and making new ones. alex haley once said, “family is link to our past, bridge to our future,” and so it is with tms. it seems like only yesterday my tie, and waiting in the hall to meet the person who i hoped would become my doctoral advisor. the year was , tms was celebrating the th anniversary of dislocations, and bill nix became not only my advisor but a life-long friend and mentor. fast forward a few decades and i am delighted to be able to attend tms meetings with my own students and make friends, join committees, organize symposia, become tms young leaders, and bring their own students into the tms family. yearly gatherings at the tms annual meeting and materials science & technology (ms&t) are the heart and soul of our society, but tms staff and volunteer promoting the future of our profession year-round. with that in mind, when i am asked what i want to accomplish during my year as tms president, i am reminded that whatever we achieve will be the result of collaborative teamwork. paradoxically, my vision for tms involves both staying the course and pursuing opportunities for change. there is much that tms does right and that its members desire in a professional society. dynamic meetings, a tangible sense tms: a link to our past; a bridge to our future kevin j. hemker, tms president of community, a tradition of volunteer engagement and ownership, and a diverse and informed perspective on the interplay of science and technology are all tremendously valuable tms hallmarks. the desire to protect them is widespread and broadly shared, and that is how it should be. nevertheless, the world is changing around us and tms must vigorously seek out improve the overall experience that it offers its members. alan h. epstein, vice president, technology and environment, pratt & whitney, once told me that when he was an academic at the massachusetts institute of technology, he worked on problems. when he moved to industry, he learned that problems are called opportunities. tms opportunities where others see problems. we cannot afford to ignore the changes that are occurring around us. changes in our key industries, the advancement of science and technology, the manufacturing of materials, the creation of digital datasets, the education of our students, and the ways that we communicate and interact with each other are all are fast becoming the new reality. as a sailor, i know that boats sail truest with a steady hand on the tiller, constant attention to detail, and a series of small adjustments. so it is with organizations, where well thought-out strategic plans are preferable to hasty tactical adjustments. the tms strategic plan emphasizes promoting diversity within our society, accelerating industrial engagement, thinking globally, and addressing pressing societal needs related to energy, the environment and innovation. it can be read on the tms website, but i would like in this article to kevin j. hemker “the world is changing around us and tms must vigorously seek out opportunities enhance and improve the overall experience that it offers its members.” jom, vol. , no. , https://doi.org/ . /s - - - Ó the minerals, metals & materials society hemker jo themagazine focus on the need for increased inclusivity, because i believe we must fully engage and empower all of our members to capitalize on the opportunities that lie before us. the tms board of directors has been actively reviewing our selection processes need widespread engagement at all levels. did you realize that tms symposia and workshops are organized from the bottom up in our technical committees? tms has three dozen such committees, if you are not a member of one, please join one. if you have never organized a symposium, ask a senior colleague to teach you how. veteran tms members, please invite a junior member to join a committee or to help you co-organize a symposium. the tms divisions that offer expanded opportunities for engagement and provide each member with a home base within the greater society. the tms board of directors, tms staff, and board-level committees play an important role in assuring that the overall impact of the society is greater than the sum of its parts. tms is best served when cultural, and demographic diversity of our entire membership. since this is supposed to be an introduction, let me close with a few words about myself. i view life as a series of adventures. i grew up in northwest ohio, university of cincinnati, ventured west to stanford for graduate school, and then east to switzerland for a three-year postdoc. for the past years, i have had the privilege of being a professor of mechanical engineering, materials science and engineering, and earth and planetary sciences at johns hopkins university. my wife, dr. maria oliva-hemker, was exiled from cuba when she was young and is now the stermer bowel disease and director of pediatric gastroenterology, hepatology, and nutrition at the johns hopkins university school of medicine. we have two sons; james who is a freshman at stanford university and michael, an th grader at the gilman school in baltimore. i am also proud of my academic family tree, and in particular, the branch that is growing at johns hopkins. working with so many talented young scientists and witnessing the digital revolution that we are immersed in, i am convinced that there has never been a better time to be a materials professional. thomas freedman once described the global energy crisis as, “the opportunity of a lifetime disguised as a series of unsolvable problems”. what more could an engineering society that sees problems as opportunities ask for? tms board of directors kevin j. hemker was officially installed as the tms president at the tms annual meeting & exhibition in march. the following individuals join him on the tms board of directors to lead the society in the coming year: tms president kevin hemker professor and chair, johns hopkins university tms past president david deyoung director of r&d, breakthrough technology, alcoa tms vice president james foley scientist, los alamos national laboratory tms financial planning officer adrian deneys business development manager, praxair, inc. tms director, professional development chester van tyne professor emeritus, colorado school of mines tms director/chair, content development & dissemination michele manuel professor, university of florida tms director/chair, member & student development amy clarke associate professor, colorado school of mines tms director/chair, programming brad boyce senior member for the technical staff, sandia national laboratories tms director/chair, public & governmental affairs john howarter assistant professor, purdue university tms director/chair, extraction & processing division cynthia belt energy management consultant, metals energy management llc tms director/chair, functional materials division raymundo arroyave professor, texas a&m university tms director/chair, light metals division alan luo professor & director, ohio state university tms director/chair, materials processing & manufacturing division corbett battaile principal member, technical staff, sandia national laboratories tms director/chair, structural materials division ellen cerreta deputy division leader, los alamos national laboratory tms secretary/executive director james robinson 	tms: a link to our past;
a bridge to our future 	 tms board of directors ist : book of abstracts general rights copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.  users may download and print one copy of any publication from the public portal for the purpose of private study or research.  you may not further distribute the material or use it for any profit-making activity or commercial gain  you may freely distribute the url identifying the publication in the public portal if you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. downloaded from orbit.dtu.dk on: apr , design for sustainability and project management literature – a review ali, faheem; boks, casper; bey, niki published in: procedia cirp link to article, doi: . /j.procir. . . publication date: document version peer reviewed version link back to dtu orbit citation (apa): ali, f., boks, c., & bey, n. ( ). design for sustainability and project management literature – a review. procedia cirp, , - . https://doi.org/ . /j.procir. . . https://doi.org/ . /j.procir. . . https://orbit.dtu.dk/en/publications/ a e - af- cce- f a- fd dad https://doi.org/ . /j.procir. . . 	
   	
   transition. people’s actual everyday behaviour with regard to resource- and energy-use often deviates from their attitudes concerning environmental and climate protection as well as energy consumption (attitude- behaviour-gap). above that, potential for saving energy by means of technological innovations might remain unutilised or may even be reversed through the same mechanism. in this presentation we will focus on the relevance, analyses, and first results of metaphors in the context of the „german energiewende“. which metaphors are used? why do certain actors use typical metaphors? what is the implication for the whole process? k paper session: energy transitions (room k ) chair: kamilla karhunmaa political ecology as perspective in analyses of crises in sustainable transition: on-shore wind power in a front runner country. michael soegaard joergensen, kristian borch, sophie nyborg, laura tolnov clausen this paper investigates the societal implications of sustainable energy action plans (seap) at the local community level on the environmental, social and economic dimensions of sustain- ability. seap is based on the covenant of mayors that is the mainstream european movement involving local and regional authorities, voluntarily committing to increasing energy efficiency and use of renewable energy sources on their territories. by their commitment, covenant sig- natories aim to meet and exceed the european union % co reduction objective by . however, the local governments have trouble in managing this crucial goal because they have to combine it with the improvement of quality of life, wellbeing and local economic development. moreover, the complexity of political strategies are increased by specific budget requirements, considering in particular the presence of different budget constraints at the local level (e.g. in- ternal stability agreement) and the reduction of the budget available due to the economic crisis. for this reason there is a need to develop tools able to assess the effects of environmental and energy policies on the socioeconomic system and to assist policymakers in identifying the most effective choices. dynamics of scientific knowledge production and technology diffusion: insights from the emergence of wind energy. cristina sousa, nuno bento, margarida fontes addressing climate change requires the widespread dissemination of new low carbon technologies. this paper aims at understanding the role of science-based learning (through r&d) and experience-based learning (through technology demonstration and deployment) in the emergence of new energy technologies, in different contextual settings. it addresses the case of wind energy, tracing scientific knowledge production (measured through scientific publication) and assessing how it articulates with technology diffusion (measured as growth of unit scale of turbines and total installed capacity) over time. the analysis looks at similarities and differences in the evolving patterns in initial (denmark) and follower (portugal) markets. results reveal different patterns between countries: publication grows following the increase in capacity installation in the pioneer, whereas they co-evolve in the case of the follower. the findings provide valuable insights for the definition of science and technology policies aiming to accelerate energy innovation and its spatial diffusion. the societal implications of sustainable energy action plans (seap). giovanni bernardo the aim of this project is to frame the potential impact of seap at the local community level. we apply a system dynamics model in the case of cascina municipality as one of the decision making tool in energy planning policies with specific considerations on co emission reductions and local development. to built and calibrate this model, we used a two steps ap- proach involving participatory planning and data analysis. the modeling approach permits to decompose a complex social or behavioral system into its constituent components and then integrate them into a holistic model - i.e labor market and a simplified representation of the local economy, transport system, housing. thus, we present different scenarios showing the potential implication of local energy policies in term of transportation, environmental and economic indicators. ground-source heat in finland: success by stealth. ville lauttamäki heat pumps that produce space heating by utilising energy stored in the earth’s crust have gradually become more common in finland. currently in new detached houses the share of buildings using ground source heat (or shallow geothermal heat) is roughly % (motiva ). along with detached houses the interest for using ground source heat pumps (gshps) is also growing in larger buildings such as apartment buildings, offices and industrial facilities. this form of energy is considered renewable and is available practically everywhere in finland. main purpose of this paper is to trace factors contributing to the development of the use of gshp systems in finland from times of the energy crises in the ’s until the present day. particular interest is devoted to two time periods: turn of the ’s and ’s and the first decade of the st century. first period covers the initial introduction of gshps to finnish market and the boom-and-bust cycle that followed the energy crisis. second studied period covers a new boom in gshp installations. paper will, in a concise form, present the most important factors and transformation processes that contributed to development of ground-source heat systems. k paper session: geography of transitions (room k ) chair: peter agoston aligning innovation policy with the spatial nature of socioeconomic benefits: an analysis of the tidal kite technology innovation system from a swedish policy perspective. johnn andersson, hans hellsmark, björn sandén since public support to the development and diffusion of renewable energy technology is usually motivated by the possibility of creating global environmental benefits opec's production under fluctuating oil prices: further test of the target revenue theory Ž .energy economics � opec’s production under fluctuating oil prices: further test of the target revenue theory harri ramcharran� department of finance, college of business, uni�ersity of akron, , akron, oh, usa abstract oil production cutbacks in recent years by opec members to stabilize price and to Ž .increase revenues warrant further empirical verification of the target revenue theory trt . Ž .we estimate a modified version of griffin target revenue model using data from to . the sample period, unlike previous investigations, includes phases of both price Ž . Ž .increase s and price decrease s� s , thus providing a better framework for examining production behavior. the results, like the earlier study, are not supportive of the Ž .strict �ersion of the trt, however, evidence negative and significant elasticity of supply of the partial �ersion are substantiated. further empirical estimates do not support the competiti�e pricing model, hypothesizing a positive elasticity of supply. opec’s loss of market share and the drop in the share of oil-based energy should signal an adjustment in pricing and production strategies. � elsevier science b.v. all rights reserved. jel classifications: q ; c keywords: oil production; target revenue theory; competitive model . introduction soaring crude oil prices resulting from opec’s decisions during the s contributed to the economic recession in many energy-dependent countries. the associated repercussions such as rapid inflation, trade deficit, external debt and � tel.: � - - - ; fax: � - - - . Ž .e-mail address: ramchar@uakron.edu h. ramcharran . - � �$ - see front matter � elsevier science b.v. all rights reserved. Ž .pii: s - - ( )h. ramcharran � energy economics � budget deficit reveal the vulnerability of global economy to the price of energy. Ž .these issues are analyzed in many studies, including, fried and schultze and Ž .marquez . in response to the energy crisis, many countries developed plans on alternative sources of energy and the possibility of inter-fuel substitution. Ž . Ž . Ž .griffin and gregory , pindyck and apostolakis discuss the Ž .implications of these strategies. the first oil shock � positioned opec as an important force in the world oil market; that triggered a plethora of studies aimed to explain energy pricing and production behavior. some of these include Ž . Ž . Ž .blitzer et al. , fischer et al. , kalymon , cremer and weitzman Ž . Ž . Ž . Ž . , hnyilicza and pindyck , danielsen , newbery , verleger Ž . Ž . Ž . Ž . Ž . , adelman , griffin , dahl and yucel and gately . Ž . Ž .the methodology includes: a the theory of exhaustible resources; b game Ž . Ž . Ž .theory; c simulation; d industrial economics; and e economic efficiency hy- Ž .pothesis. mabro critically evaluates some of these approaches. an important aspect of opec’s production behavior is the propensity for some members to Ž .cheat on quotas; this phenomenon is examined by griffin and xiong . Ž . Ž .the target revenue theory trt , developed by ezzati , cremer and Ž . Ž . Ž .isfahani and teece , remains a popular and controversial theory of oil pricing and production. the theory postulates that production cutbacks occur in response to rising oil prices to equate oil revenue with investment needs. if exporting countries try to satisfy target revenue for domestic investment purposes, a backward bending supply schedule is hypothesized, thus the trt explicitly implies that a fall in prices will result in output expansion. opec’s production Ž .behavior in the mid- s seemed to be consistent with the trt. griffin estimates an empirical model of the trt for opec with data for the period � , a period of rapid price increase and finds little support of the theory. structural changes in the world oil market, the growth of non-opec supply, the Žrapid decline in oil prices the average spot price for crude fell from $ . per �barrel in to $ . in with a record low of $ . in december , see Ž . �table a appendix a and fig. and over production by some members of opec to enhance revenues warrant further testing of the trt. more importantly, in the series of production cutbacks, opec has been able to boost the price of crude beginning march to a high of approximately $ per barrel in . Ž .the wall street journal march , reports that opec, troubled by weaken- ing oil demand the faltering world economy, is moving toward reducing output to Ž .keep the us price of oil near $ a barrel bahree and herrick, . Ž .this paper uses a modified version of the model developed by griffin to the price of crude has increased steadily from $ . in february to $ . in july mainly because of opec’s decision in march to trim output by . million bpd. since then opec has been very disciplined with very high compliance, however, if price continues to increase the temptation could become intense for some members to exceed their quotas and non-opec sources to Ž .increase stanley, . https://isiarticles.com/article/ international journal of engineering and advanced technology (ijeat) issn: – , volume- , issue- s , september published by: blue eyes intelligence engineering & sciences publication retrieval number: f s / ©beiesp doi: . /ijeat.f . s abstract:-the battery energy storage system (bess) is basically used to smooth wind / solar power controlling. the constant current controller method is employed in order to eliminate the output fluctuation of photovoltaic/ bess power generation system. in this presented paper, the detailed description of the grid associated pv structure along with battery and load is modeled and simulated in matlab / simulink software. keywords: solar power, current controller, fluctuation, battery, photovoltaic (pv) i. introduction the world's electricity demand, including india, is increasing at an alarming rate, and electricity demand is ahead of supply. in the social sector of energy sector, agriculture, industry, transportation, business, or home consumes energy for day to day work. energy has become dependent on fossil fuels with limited inventory of natural gas, oil and gas. due to large amount of energy consumption, renewable sources for energy such as wind energy and solar energy plays key regarding energy generation. global warming and serious air pollution is caused by excessive and continuous. solar energy is naturally abundant and an inexhaustible source of energy. solar energy can be used in two modes: stand-alone power generation units or grid-connected power generation units, which depends upon availability of nearby grids. therefore, this can be utilized in order to supply power grid availability is lesser such as rural areas. yet another benefit of solar power is elasticity to operate wheneverneeded. to solve the current energy crisis, there exist long felt need for developing effective ways to extract power from solar radiation.with the development of materials science & power electronics, engineers are capable to endure high power demands by developing very small but powerful systems. however, “high power density” is a major problem with this type of system. however, due to their high production costs and low efficiency, these systems are rarely able to compete in the competitive market as a major power source. the consistent increase in solar cell manufacturing will ensure that these technologies may be utilized on a revised manuscript received on august, . bibekananda jena, department of electrical engineering, institute of technical education and research, siksha „o‟ anusandhan(deemed to be university), bhubaneswar, odisha, india. sonaligoel, department of electrical engineering, institute of technical education and research, siksha „o‟ anusandhan(deemed to be university), bhubaneswar, odisha, india.(email: sonali @gmail.com) renu sharma, department of electrical engineering, institute of technical education and research, siksha „o‟ anusandhan(deemed to be university), bhubaneswar, odisha, india. broader basis than the current scenario. the implementation of power control strategy known as “maximum power point tracker (mppt)” is useful in the area of renewable energy sources as it is required to improve the operational solar modules implementation[ ] . ii. modeling of pv array photovoltaic (pv) array is basically a combination of multiple units interconnected in series/parallel combination to generate the necessary current and voltage. pv arrays are mathematically modeled by using matlab that utilizes solar cells equivalent circuit model. pv arrays are configured according to model requirements. as shown in figure , a current input source is associated parallel and in series with diode in a simplified pv module structure, and pv array simulink model as illustrated in fig . fig. equivalent model of a pv module the operation of a pv array with an ns x np unit may explained by the following formula. pv module parameters can be partially achieved through manufacturer's data sheet and may attained by some estimation methods [ ]. where i pv = pv array output current [a] isc = pv module short-circuit current [a] io = saturation current of diode [a] va = terminal voltage of pv array [v] rs = series resistance [Ω] n = constant of ideal diode vt= pv module‟s thermal potential [v] smoothing control scheme of photovoltaic module through a battery energy storage system bibekananda jena, sonali goel, renu sharma smoothing control scheme of photovoltaic module through a battery energy storage system published by: blue eyes intelligence engineering & sciences publication retrieval number: f s / ©beiesp doi: . /ijeat.f . s fig. pv array matlab / simulink model. iii. modeling of battery grid associated structure batteries are intended for load supply and grids when no solar power is available. when the load is less, said battery gets charged from the array, generating extra power through said array, and if no power is supplied from the array, the load consumes whole energy of battery. in order to prevent the battery's depth of discharge, the charging state is monitored and whenever battery gets below %, said battery gets disconnected from the load through breaker. the subsystem of battery designed in amatlab / simulationis as illustrated in fig . fig. subsystem of battery in matlab/simulink iv. on-grid photovoltaic (pv)/ battery system pv array & battery are interlinked with dc bus through a dc / dc converting unit associated with said grid through inverter. “battery energy storage systems” helps in balancing power in between pv and load demand. when power generation exceeds demand, pv module charges said battery, and when power generation falls below demand, said load consumes battery energy. the circuit diagram of on-grid hybrid pv / battery system is shown in figure . fig. outline of the on-grid hybrid pv/battery generation system . power control at pv array side and mppt pv module must work at some well-defined voltage that resembles to mpp as per operating conditions such as irradiance and temp. therefore, for this purpose the mppt technology is applied. conventionally, numerous mppt technologies are proposed & implemented, some of them are lookup table method, “perturbation and observation (p & o) method” and calculation method [ ] [ ] [ ]. . boost converteralong with its controller fig. boost converter and controller scheme in a dual-phase pv generation, the chopper network is deployed as dc / dcconverter. since the voltage coming out through pv module is less, by usage of boost converter circuit permits the use of a low-voltage pv array, thereby reducing the total price. capacitor interconnected in between pv module and converter & it is deployed in order to decrease harmonics. fig illustrates outline of boost converter network along with its control system. international journal of engineering and advanced technology (ijeat) issn: – , volume- , issue- s , september published by: blue eyes intelligence engineering & sciences publication retrieval number: f s / ©beiesp doi: . /ijeat.f . s . battery energy storage system “battery energy storage system (bess)” comprises of a battery bank, bi-directionaldc / dc converting unit and controlling structure [ ]. the system must capable of working with twoinstructions: one must charges said battery for storing excess energy and discharge the energy through the load. in the paper as illustrated in fig , the bess is usually associated with dc bus using a bidirectional dc / dc converter. fig. the bi-directional dc/dc converter grid considered as source of backup power, and battery provides short-term power in order to meet demand of load that the pv module cannot meet, especially during solar power fluctuations. . controlling scheme by grid-associated inverter pv module & battery are interconnected with said grid through inverter. this inverter employed in spwm constant current control method, the inductance current closely tracks the sinusoidal reference current command, and obtains the low thd injection current. v. simulation result according to model and controlling method, it‟s implementedin on-grid pv generation in matlab / simulink as illustrated in fig . in this presented paper, the generated power of pv module is similar with said load demand and in case of the change in solar irradiancethe pv power generation is not similar with load demand & the battery is charged / discharged to store / discharge energy. fig . simulation model of hybrid generation system the output waveform obtained from simulation model as illustrated in fig (a), (b), (c), (d), (e) and (f). smoothing control scheme of photovoltaic module through a battery energy storage system published by: blue eyes intelligence engineering & sciences publication retrieval number: f s / ©beiesp doi: . /ijeat.f . s figure (a) output voltage of pv array figure (b) output current of pv array figure (c) output power of pv array figure (d) grid current figure (e) load current figure (f) inverter current vi. conclusion this paper studies about on grid pv / battery system for power generation. to utilize solar energy efficiently, it tracks maximum power point of pv module and generates most power with grid. the “p & o method” can change the perturbation as the actual operating point changes. according to result, both tracking speed and algorithm accuracy are met. pv production changes as solar irradiance or temperature fluctuates. the charging and discharging of battery is performed to maintain a power balance between pv power generation and demand, improving overall system stability. references . mummadiveerachary, "control of ti-sepic converter for optimal utilization of pv power", iicpe, new delhi. . m. berrera, a. dolara, r. faranda and s. leva, “experimental test of seven widely-adopted mppt algorithms”, ieee bucharest power tech conference, june th - july nd, bucharest, romania. . c.hua and cshen, “study of maximum power tracking technique and control of dc/dc converter for photovoltaic system,”,ieee computer soc.press,newyork,usa, . trishanesram. patrick l, chapman, "comparison of photovoltaic array maximum power point tracking techniques", ieee transaction on energy conversion, vol , no. , pp. - , . . jingang han, tianhao tang, yao xu, et at, "design of storage system for a hybrid renewable power system", nd conference on power electronics and intelligent transportation system, vol , pp. - , hindawi publishing corporation journal of nanomaterials volume , article id , pages http://dx.doi.org/ . / / editorial functional nanomaterials for optoelectric conversion and energy storage yongfeng luo, li li, sanqing huang, tao chen, and hongmei luo institute of mathematics and physics, central south university of forestry and technology, changsha, hunan , china shanghai engineering research center of aquatic-product processing & preservation, college of food science and technology, shanghai ocean university, shanghai , china school of materials and textiles, zhejiang sci-tech university, hangzhou, zhejiang , china department of macromolecular science and engineering, case western reserve university, cleveland, oh , usa department of chemical engineering, new mexico state university, las cruces, nm , usa correspondence should be addressed to yongfeng luo; yongfengluo@csu.edu.cn and li li; l-li@shou.edu.cn received march ; accepted march copyright © yongfeng luo et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. the rapid increase in industrialization, urbanization, and population growth has led to a pronounced rise in the global energy demands [ – ]. with depleting fossil fuels and grow- ing concern on environmental protection, urgent research efforts are needed to find alternative energy resources that are efficient and economically and ecologically friendly. since energy resources such as solar power are intermittent, but the usage is increasing in numerous portable electronic devices, efficient means have to be found for energy storage and trans- portation. a number of electronic, photonic, and optoelec- tronic devices have been proposed for this purpose, such as photovoltaic solar cells, batteries, supercapacitors, field effect transistors, fuel cells, thermoelectric, thermal-photo cata- lysts, and luminescence display devices. the main purpose of this special issue is to use advanced nanomaterials and nanotechnologies in designing systems for an efficient interconversion of different energy forms among thermal, photonics, and electrical energy. graphene, carbon nanotube, and conducting polymer may represent the most studied materials where the nanoscale design permits their more efficient performance in a number of energy conversion and storage devices. all devices dealing with conversion of energy forms and storage were considered for this special issue. the energy crisis is evident from the fact that the global energy consumption has been accelerating at an alarming rate due to the rapid economic expansion worldwide, increase in world population, and ever-increasing human reliance on energy-based appliances. by , advanced technologies for both optoelectric conversion (e.g., solar cells) and energy storage (e.g., supercapacitors and batteries) are being exten- sively studied around the world. functional nanomaterials have opened up new fields in materials science and engineer- ing to meet this challenge. in particular, nanomaterials and nanotechnologies have been demonstrated to be an enabling technology for creating high-performance optoelectric con- version and energy storage devices. like all other devices, performance of the energy-related devices depends strongly on the properties of the materials they employ. recent devel- opment in materials science, particularly carbon nanomate- rials, has facilitated the research and development of energy technologies as (shown in the works by y. luo et al. and l. li et al.). comparing to conventional energy materials, carbon nanomaterials possess some unusual size-surface-dependent (e.g., morphological, electrical, optical, and mechanical) properties useful in enhancing energy conversion and storage performance. specifically, considerable efforts have been made to utilize the unique properties of carbon nanotubes (cnts) and graphene as optoelectric conversion materi- als. tremendous progress has been achieved in developing carbon nanomaterials for high-performance optoelectric- conversion and energy storage devices. the special issue was focused on the progress in the research and development of carbon nanomaterials during the past twenty years or so. the journal of nanomaterials advanced energy conversion (i.e., solar cells) and storage (i.e., supercapacitors and batteries) was also discussed along with some challenges and perspectives in this exciting field. the other functional nanomaterials are also published in this special issue besides graphene, carbon nanotube, and conducting polymer. it mainly focuses on preparations, cha- racterizations, functionalizations, and properties of nano- particles, nanostructured coatings, films, membranes, nano- porous materials, and nanocomposites. the fundamental understanding of the mechanisms on materials and processes at nanoscale was highlighted. yongfeng luo li li sanqing huang tao chen hongmei luo references [ ] k. kalyanasundaram and m. grätzel, “themed issue: nanoma- terials for energy conversion and storage,” journal of materials chemistry, vol. , no. , pp. – , . [ ] x. wan, y. huang, and y. chen, “focusing on energy and opto- electronic applications: a journey for graphene and graphene oxide at large scale,” accounts of chemical research, vol. , no. , pp. – , . [ ] g. centi and s. perathoner, “the role of nanostructure in im- proving the performance of electrodes for energy storage and conversion,” european journal of inorganic chemistry, no. , pp. – , . [ ] l. dai, “functionalization of graphene for efficient energy con- version and storage,” accounts of chemical research, vol. , no. , pp. – , . submit your manuscripts at http://www.hindawi.com scientifica hindawi publishing corporation http://www.hindawi.com volume corrosion international journal of hindawi publishing corporation http://www.hindawi.com volume polymer science international journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume ceramics journal of hindawi publishing corporation http://www.hindawi.com volume composites journal of nanoparticles journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume international journal of biomaterials hindawi publishing corporation http://www.hindawi.com volume nanoscience journal of textiles hindawi publishing corporation http://www.hindawi.com volume journal of nanotechnology hindawi publishing corporation http://www.hindawi.com volume journal of crystallography journal of hindawi publishing corporation http://www.hindawi.com volume the scientific world journal hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume coatings journal of advances in materials science and engineering hindawi publishing corporation http://www.hindawi.com volume smart materials research hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume metallurgy journal of hindawi publishing corporation http://www.hindawi.com volume biomed research international materials journal of hindawi publishing corporation http://www.hindawi.com volume n a n o m a te ri a ls hindawi publishing corporation http://www.hindawi.com volume journal of nanomaterials university of richmond 	skip to main content 	skip to footer 	 		 			× 			close modal 		 		 			 				 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				 				 						legal policies 	web accessibility 	site feedback 				 			 		 		 			 				administration 					human resources 	president's office 	provost's office 	university communications 	student development 	information services 	business affairs 	advancement 			 			 				general info 					ur facts 	academic calendar 	newsroom 	directory 	ur spidershop 	accreditation 	diversity, equity, & inclusion 	compliance 			 			 				schools 					arts & sciences 	business 	leadership studies 	law 	professional & continuing studies 			 			 				health & safety 					ur alert 	university police 	emergency preparedness 	facilities 	ur well 	student health center 	counseling and psychological services 	center for awareness, response, and education 	covid- response 	caps peer support warmline 			 		 	 	 		 			© – university of richmond 		 	 hindawi publishing corporation cardiovascular psychiatry and neurology volume , article id , pages doi: . / / review article cardiovascular risk factors promote brain hypoperfusion leading to cognitive decline and dementia jack c. de la torre department of psychology, university of tx at austin, austin, tx , usa correspondence should be addressed to jack c. de la torre, jcdelatorre@comcast.net received august ; accepted october academic editor: christian humpel copyright © jack c. de la torre. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. heart disease is the major leading cause of death and disability in the world. mainly affecting the elderly population, heart disease and its main outcome, cardiovascular disease, have become an important risk factor in the development of cognitive decline and alzheimer’s disease (ad). this paper examines the evidence linking chronic brain hypoperfusion induced by a variety of cardiovascular deficits in the development of cognitive impairment preceding ad. the evidence indicates a strong association between ad and cardiovascular risk factors, including apoe , atrial fibrillation, thrombotic events, hypertension, hypotension, heart failure, high serum markers of inflammation, coronary artery disease, low cardiac index, and valvular pathology. in elderly people whose cerebral perfusion is already diminished by their advanced age, additional reduction of cerebral blood flow stemming from abnormalities in the heart-brain vascular loop ostensibly increases the probability of developing ad. evidence also suggests that a neuronal energy crisis brought on by relentless brain hypoperfusion may be responsible for protein synthesis abnormalities that later result in the classic neurodegenerative lesions involving the formation of amyloid-beta plaques and neurofibrillary tangles. insight into how cardiovascular risk factors can induce progressive cognitive impairment offers an enhanced understanding of the multifactorial pathophysiology characterizing ad and ways at preventing or managing the cardiovascular precursors of this dementia. . introduction it has been known since the ebers papyrus [ ] in bc, and probably even before then, that the brain and heart are intimately connected. the ancient greeks and aristotle in particular believed that the function of the brain was to “cool” the blood while the heart was the source of mem- ory. this belief was consolidated by religious and scientific dogma for centuries. it took the most significant achieve- ments in medicine in the th and th centuries by the belgian anatomist andreas vesalius and the english physi- cian william harvey to challenge that prevailing dogma and describe a more accurate account of the cerebral circulation as well as the heart’s continuous pumping action inside a very precise circuit. fast-forwarding to the th century, several researchers in the late s became aware of an intriguing link between a sick heart and the start of cognitive deterioration that often led to vascular dementia (vad) [ ]. this link came to be known as “cardiogenic dementia”, and although it remained largely ignored for many years as a casual observation, it eventually opened the door slightly to a fascinating field where cognitve impairment and dementia could be triggered by a bad heart [ ]. research in the early s additionally began to suggest that cardiovascular disease could also signal the start of alzheimer’s disease (ad), an assumption that, as will be seen below, has gained evidence-based support from more detailed studies published in the last decade. the suggested link between cardiovascular deficits as a risk to ad was important not only because it has now been generally accepted to be true but because it implied that other extra- cardiac vascular risk factors might also play a crucial role in the initiation of this dementia by possibly sharing common pathological pathways or markers common in ad. moreover, the therapeutic implications of controlling such vascular risk factors to ad have become one of the most important inroads in the search to lower the rising prevalence of ad and vad [ , ]. cardiovascular psychiatry and neurology cardiovascular disease comes in many forms, and its outcome is dependent on the patient’s age, prior history, life style, primary prevention, genetics and pathological fac- tors affecting structural, and hemodynamic function. car- diovascular disease affects the heart vessels which affect the structural tissue of the heart and can be classified as coronary (the most common), valvular, cardiomyopathic, arrhythmic, congenital, and heart failure [ ]. due to space constraints, only some forms of cardiovascular disease will be reviewed here although it is anticipated that most forms of heart disease which lower cerebral blood flow through an impairment in cardiac structure or physiology will also be found to increase ad risk. . cardiovascular disease, cognition, and cerebral autoregulation the original association between cardiac pathology and cog- nitive dysfunction described above as cardiogenic dementia was based on the high incidence of cardiac dysrhythmias seen in patients with dementia solely due to vascular causes [ ]. thus, chronic heart block and dysrhythmias that were shown to lower cardiac output and lead to persistent cognitive dysfunction and dementia were rightly believed to stem from a diseased heart [ ]. when arrhythmias were suspected to cause cognitive dysfunction, it was found that cognitive dysfunction could be attenuated or reversed with cardiac pacing [ , ]. restoration of cognitive ability by pacing was attributed to bringing the impaired cerebral perfusion back to normal by maintaining an adequate heart rate [ ]. at the present time, brain hypoperfusion that develops from low cardiac output or hypotension has been shown to cause cognitive deficits in attention and memory [ ], and more recent studies propose that these deficits develop from brain hypoperfusion and can lead to ad [ – ]. when hypotension is involved, its link to cognitive decline has been generally ignored in clinical practice. one reason for this attitude is the current dogma that low sys- temic blood pressure does not cause brain dysfunction be- cause compensatory cerebral autoregulation prevents brain hypoperfusion from being activated [ ]. however, studies have confirmed, particularly in the elderly, that cerebral auto- regulation does not necessarily protect the brain from chronic low blood pressure and low cardiac output, an out- come that can result in cerebral blood flow insufficiency and its accompanying consequences [ , – ]. evidence to support the concept linking cognitive func- tion to cerebral perfusion also comes from studies showing that cerebral blood flow rises in healthy subjects following moderate exercise but cerebral perfusion may not increase if cardiac output is limited by cardiac pathology affecting, for example, heart rate from a dysrhythmia [ ]. these findings indicate that cerebral autoregulation does not reverse brain hypoperfusion when cardiac output is compromised by specific cardiac pathology. normally, cereb- ral autoregulation maintains a constant blood flow to the brain between – mm hg mean arterial pressure. the main function of cerebral autoregulation is to maintain cerebral perfusion pressure by signaling brain arterioles to dilate or constrict during changes in arterial blood pressure [ ]. cerebral autoregulation may become impaired with aging [ ] but it is not clear why or how. the long- term evolution for potential brain damage during aging can involve decades. it may develop from atherosclerosis, arter- ial stiffness, or cardiovascular disease which can impair cere- bral autoregulation homeostasis and result in brain hypoper- fusion (figure ). brain hypoperfusion would preferentially affect the older brain which is already primed to neurome- tabolic dysfunction by decreased delivery of energy sub- strates to brain cells [ – ]. studies have reported that normal aging reduces cbf about % at age as compared to age [ – ], so any additional burden which further lowers cerebral perfusion in addition to that seen during aging could damage or kill vulnerable neurons [ , ]. glucose is the primary molecule used to create energy fuel for mammalian brain cells and the brain depends on a continuous and optimal flow of blood to maintain normal brain cell activity and structural integrity [ ]. if impaired cerebral autoregulation is indeed one of the culprits that contributes to cognitive failure in the elderly following chronically evolving vascular insults, a num- ber of cerebral vasoactive molecules may be coconspirators in the development of ad, among them vasodilators such as endothelial nitric oxide, adenosine, prostacyclin, and epoxy- genases that yield epoxyeicosatrienoic acids and vasocon- strictors such as thromboxane a , endothelin- , and - hydroxyeicosatetraenoic acids ( -hete). curiously, phar- macologic inhibition of -hete appears to impair cerebral autoregulation in vivo [ ]. another cyclic burden on the heart that generates reduced blood flow to the brain is the finding that cerebral hypoperfusion can impair cerebrovascular reactivity [ , ], possibly as a result of reduced nitric oxide release from damaged endothelial cells [ ]. other vascular risk factors, such as chronic hypertension can shift the limits of autoregulation toward higher blood pressure levels [ ]. this adaptative mechanism protects the brain against hypertension to some degree but can also ren- der it more vulnerable to cerebral hypoperfusion in elderly individuals who are aggressively treated with antihyper- tensive medication that induces hypotension. for this reason, it has been argued that careful consideration should be exer- cised when elderly persons with mild or moderate hyper- tension are given anti-hypertensive therapy, since such a treatment may lead to unregulated hypotension and risk of dementia [ , ]. not surprisingly, when dynamic cerebral autoregulation is impaired from unilateral carotid artery stenosis, carotid endarterectomy, or stenting can reverse the effects of the brain dysautoregulation [ ]. recent evidence indicates that patients undergoing carotid artery stent placement for ather- osclerosis showed either neurocognitive improvement at the end of months or no worsening in status from baseline, suggesting that this procedure is safe and possibly effective [ ]. cerebral autoregulatory dysfunction can also occur with vertebral artery disease although little can be done cardiovascular psychiatry and neurology left ventricular wall motion abnormalities aortic valve regurg mitral valve thickening aortic valve thickening atrial fibrillation heart failure hypoxia vascular resistance hypertension stroke av node aortic stiffening left ventricular hypertrophy coronary artery disease interior vena cava superior vena cava cardiovascular risk factors leading to brain hypoperfusion and cognitive loss hypotensionreduced cardiac output apoe allele figure : cardiovascular risk factors reported to promote progressive cognitive decline leading to dementia in the elderly population. reduced cardiac output (< . ± . l/min) in the absence of clinically identified stroke can promote hypotension, heart failure, hypoxia, and increased (↑) vascular resistance associated with cognitive decline [ , , , ] and ostensibly, alzheimer’s disease [ ]. aortic and mitral valve regurgitation (regurg) and/or valvular thickening can impair normal cardiac output. aortic stiffening is associated with aging, hypertension, and atherosclerosis and is believed to result in brain microvascular damage, leading to cerebral hypoperfusion and cognitive decline [ , ]. left ventricular wall motion abnormalities mainly result from myocardial ischemia. atrial fibrillation is a risk factor for cardioembolic events, especially stroke and for alzheimer’s disease [ ]; it is the most common arrhythmia in the elderly population. epidemiologic and clinical evidence indicates that coronary artery disease, the leading cause of mortality in the united states, is a potential risk factor for alzheimer’s disease [ , ]. left ventricular hypertrophy may be asymptomatic, mild, moderate, or severe and is a reported risk factor to cognitive decline in middle age but loses its predictive value in advanced age [ ]. presence of the apoe allele, a genetic risk factor to alzheimer’s dementia, increases the risk of coronary heart disease by about % [ ]. presence of two or more cardiovascular risk factors may significantly accelerate the onset of cognitive deficits [ ]. surgically to correct impaired blood flow from these lesioned vessels [ ]. despite the obvious importance that connects some types of heart disease to cognitive impairment (figure ), it has been largely ignored by many researchers in the field and by most cardiologists as evidenced by the absence of present- ations discussing this topic in alzheimer or heart-related conferences. we are aware of scant few papers that have ques- tioned whether cognitive decline generated by low cardiac output in the mildly symptomatic elderly can lead to ad or vad [ , ]. moreover, very few studies have examined the role of cardiac disease as a source of cerebral hypoper- fusion [ – ] despite evidence that the presumed mecha- nism leading to cerebral hypoperfusion secondary to reduced cardiac output is left ventricular dysfunction associated with a reduced stroke volume [ ]. the ultimate fallout from low cardiac output on the brain is that hemodynamic pump dysfunction in the older person can significantly lower blood flow to brain cells via cerebral hypoperfusion, thereby diminishing energy substrate supply needed for normal brain cell metabolism [ – ]. . cardiovascular disease as a vascular risk factor to alzheimer’s disease epidemiological findings indicate that a broad spectrum of cardiovascular risk factors, including heart failure, thrombotic events, hypertension, hypotension, homocys- teine, hypercholesterolemia, c-reactive protein, coronary artery disease, valvular disease, heart failure, apoe , and atrial fibrillation are more common in the elderly. these con- ditions are reported to contribute to cognitive dysfunction and decline affecting performance in executive functions, attention, learning, psychomotor speed, verbal fluency, men- tal alertness, and memory [ – ] (figure ). consequently, the neuropathologic link between the cardiac abnormalities listed above and their satellite off-shoots, such as amyloid angiopathy and presence of the apoe genotype [ ], is seem to contribute to a vascular complex that appears to target ad via specific cardiopathic pathways. . low ejection fraction or low cardiac output ejection fraction a measure of stroke volume based on the dimensions of the left ventricle which is the main pumping chamber and refers to the percentage of blood that is pumped out of a filled left ventricle with each heartbeat contraction. cardiac output is a measure of stroke volume based on forward flow velocities reflecting the amount of blood exiting the heart, as measured by liters per minute. there is mounting epidemiologic evidence that ad is associated with an increased risk of symptomatic left ventricular dysfunction (lvd) [ ]. lvd produces many changes in the structure and function of the heart through cardiovascular psychiatry and neurology executive function psychomotor speed verbal fluency mental flexibility and sequencing memoryabnormal mmse cerebral hypoperfusion disturbed hemodynamics energy substrate delivery clearance of abeta and various toxins proteinopathy and abeta misfolding c a t c h hypothetical cardiovascular disease cascade in cognitve decline cardiovascular disease risk factors figure : hypothetical model based on the collective evidence available showing how cardiovascular risk factors give rise to disturbed hemodynamic flow patterns inducing cerebral hypoper- fusion. chronic insufficiency of blood flow to the brain may reach a critically attained threshold of cerebral hypoperfusion (catch) [ ] responsible for lowered energy substrate delivery and creation of a neurono-glial energy crisis, initially in brain regions where memory and learning are localized. further downstream, an increase in protein pathology (↑ proteinopathy), featuring protein misfolding of abeta peptide, ensues followed by impaired clearance of waste products including abeta [ ]. reduced abeta clearance from the brain is possibly due, as we predicted, to an impaired microcirculation causing an ineffective efflux of waste products [ ]. deficits (↓) of nonmemory executive function, verbal and mental abilities, and psychomotor speed are ostensibly the first subclinical changes in cognitive dysfunction prior to more advanced cognitive impairment. a variety of mechanisms. it can lead to reduced ejection fraction, heart failure, heart attack, and other cardiovascular complications. low ejection fraction or low cardiac output in elderly patients with heart failure is reported to be associated with impairments of specific aspects of attention, specifically continuous vigilance and discriminability [ ]. low cardiac output has been found to be associated with impairment of executive function, including sequencing and planning [ ] (figure ). cardiac resynchronization therapy is a relatively recent intervention that has been shown to increase cardiac func- tion in symptomatic heart failure resulting from systolic dys- function. it does this essentially by improving cardiac hemo- dynamics, ventricular contractility, and stroke volume while reducing myocardial energy consumption [ ]. this tech- nique has shown usefluness in improving executive and visu- ospatial functioning and neurocognitive measures of atten- tion in patients with low left ventricular ejection fraction as compared to similar patients who did not undergo cardiac resynchronization therapy [ , ]. age may be a determinant of potential cognitive dys- function. when ejection fraction dropped below %, patients older than years showed a significant decline in memory performance, specifically, verbal delayed recall and recognition as compared to those under years who were able to maintain stable memory function or similar ejection fraction levels [ ]. although subtle cognitive changes may progress to global cognitive decline and dementia, this con- clusion requires further work to prove or disprove. neverthe- less, it provides a preventive guide when clinical testing detects elderly patients with low ejection fraction or card- iac output. these findings show that advancing age, car- diovascular pathology, and cognitive function are closely linked, and that novel interventions to correct impending cardiac hemodynamic homeotassis could make a difference in preventing or significantly slowing a potential pathway to dementia. . atrial fibrillation atrial fibrillation is a heart rhythm disorder (arrhythmia) usually involving a rapid heart rate. in the normal heart, the rate of ventricular contraction is the same as the rate of atrial contraction. in atrial fibrillation, however, the rate of ventricular contraction is less than the rate of atrial contrac- tion. this condition can lead to a decrease in cardiac output diminishing the amount of blood pumped into the body by the ventricles because the atria are unable to fill the ventricles adequately due to their rapid rate of contraction and their absence of normal contractions. the risk of atrial fibrillation increases with age and is more common in males [ ]. not surprisingly, studies have shown an association between atrial fibrillation and diminished cognitive function leading to ad in the absence of stroke, high blood pressure, and diabetes [ ]. the risk of ad after atrial fibrillation has been reported stronger than for vascular dementia when cerebrovascular events were examined in a population-based study [ ]. a more recent prospective study of , patients with a mean average age of showed a significant increase in cognitive impairment incidence during a year follow-up period [ ]. atrial fibrillation also appears to involve a significant conversion to dementia in nondemented subjects whether or not cognitive impairment was present [ ]. many studies have shown that atrial fibrillation induces significant brain hypoperfusion [ ] which can compromise the aging cere- brovasculature. although the true mechanism that associates atrial fibrillation to cognitive impairment is unclear, a sus- picion is that cerebral hypoperfusion may be triggered by the chronic arrhythmia present [ ]. . aortic and mitral valve prolapse few studies have examined the effects of myocardial valve damage and its possible effect on cognitive function. autopsy findings have reported significant aortic and mitral valve damage in ad subjects when compared to a nondemented control group [ ]. this association between valvular dam- age and ad is consistent with the presence of brain hypo- perfusion at an early stage of ad pathology [ ], or even prior to ad, an observation that supports previous findings [ ]. a more recent study revealed that left atrial fatigue cardiovascular psychiatry and neurology which is a contributor of atrial fibrillation can develop from mitral valve damage involving either mitral valve prolapse or valvular regurgitation [ ] (figure ). mitral valve prolapse and abundant senile plaques char- acteristic of ad were found at autopsy in the brains of elderly subjects who died from critical coronary artery disease but were not demented [ ]. this finding was in contrast to nonheart disease subjects who showed almost no ad lesions when compared to heart disease patients [ ]. the link between senile plaque formation and cardiac valvular damage implies that structural cardiac damage may influence the formation of neurodegenerative lesions even when no dementia has yet been expressed. it is tempting to speculate that left atrial dysfunction stemming from mitral valve damage can be a therapeutic target that is preventable either by surgical or pharmacologic approaches to lessen the risk of ad in such patients. more work should determine whether this speculation has any merit. . hypertension according to the american heart association, some million americans have high blood pressure although about % of these show only mild hypertension. the incidence of hypertension in other countries such as china appears to be even higher due to their high salt intake. high blood pressure is estimated to affect % of the adult population in developed countries such as the usa and canada. it is well established that high blood pressure can increase the risk of stroke and heart disease and decrease life expectancy. many studies including the framingham, the kungsholmen, and the honolulu-asia aging studies have implicated impaired cognitive function to hypertension in geriatric patients [ – ]. it has also been known for some time that hypertension in the elderly is a potential risk factor to ad [ – ]. the mechanisms linking hypertension to alzheimer’s disease remain to be elucidated, but damage to brain endo- thelial cells and smooth muscle cells that control cerebral blood flow is suspected to be a culprit due to the pulsatile pressure changes on the cerebral microvasculature generated by chronic hypertension [ ]. these hemodynamic and structural changes produced on the brain by the heart can induce chronic brain hypoperfusion leading to white matter lesions as seen on cerebral magnetic resonance imaging of ad patients and constitute a good marker for this dementia [ ]. when lacunar infarcts or accumulation of lesions in the white matter secondary to chronic hypertension lead to subsequent cognitive deterioration, it has been proposed that disconnection of cortico-subcortical pathways may be involved [ ]. possible neurotoxicity from the increased pro- duction of amyloid-beta in hypertensive patients may com- promise cerebral perfusion by promoting vasoconstriction and/or cerebral angiopathy [ ]. what is still not clear is precisely how hypertension increases the incidence of ad, particularly in those not treated with antihypertensives [ ]. also unclear is whether antihypertensive therapy can significantly reduce or reverse the cognitive decline that can herald dementia. we have theorized that chronic brain hypoperfusion generated by increased vascular resistance from hypertension may be a key factor linking high blood pressure and ad [ , ]. brain hypoperfusion resulting from hypertension can result from vessel stiffness secondary to atherosclerosis, increased vas- cular resistance, and disturbed hemodynamic flow patterns [ , ] and is plausibly the basis for the gradual cognitive decline seen during advanced aging [ ]. recent randomized controlled trials including syst- eur, progress, hope, mrc, shep, scope, and hyvet-cog examined the impact of antihypertensive therapy with cognitive function as a secondary end point. three studies found positive results using antihypertensive therapy in preventing cognitive decline and dementia while the other four (mrc, shep, scope, and hyvet-cog) trials reported no significant differences between treated and untreated subjects [ ]. since absence of evidence is not necessarily evidence of absence, a cautious conclusion can be advanced that the posi- tive results of syst-eur, progress, and hope open the possibility of discovering target-specific cardiovascular ther- apies to lower ad and vad prevalence by correcting the structural and physiological deficits encountered by a stres- sed heart. for starters, a recent large population-based study of persons years and older in cache, utah, reported that the use of antihypertensive medication, including angiotensin- converting enzyme inhibitors, β-blockers, calcium channel blockers, and diuretics significantly lowered the risk of ad [ ]. the greatest reduction in ad risk ( %) was seen in the group using potassium-sparing diuretics, but the immediate reason for this finding was not clear [ ]. it is possible that increased potassium levels are associated with a reduced risk of dementia [ ] while low potassium concentrations have been associated with oxidative stress [ ], aggregation [ ], and vasoconstriction [ ], conditions which can result in chronic brain hypoperfusion and, according to us, contribute to ad [ ]. high blood pressure is known to reduce cerebral blood flow but the mechanisms involved in this action remain unexplained [ ]. since cardiac output remains normal during high blood pressure, two possible causes for the cerebral blood flow reduction may occur in hypertensive individuals. first, hypertension can increase systemic vascu- lar resistance and slow down normal blood flow. second, cerebral blood flow may fall when blood pressure is high due to direct damage to brain endothelial cells that produce the vasodilator nitric oxide [ ]. thus, there is an implied possibility that therapy aimed at controlling high blood pressure using potassium-sparing diuretics, increasing cere- brovascular nitric oxide, or protecting endothelial cells in the brain could prevent or delay the onset of ad by coun- teracting the appearance of chronic brain hypoperfusion in the hypertensive population [ ]. in fact, increasing vascular nitric oxide in brain should provide another benefit. vascular nitric oxide activation has been shown to downregulate bace- , the initial proteolytic enzyme responsible for aβ cardiovascular psychiatry and neurology peptide synthesis, while upregulating bace- , the enzyme that cleaves amyloid precursor protein (app), so that aβ production cannot take place [ ]. . hypotension hypotension is a common clinical condition that commonly affects elderly persons over age . the most common causes of hypotension are blood pressure anomalies, dehydration, bleeding, medications, genetics, and cardiac pathology, including carotid sinus and vasovagal syndromes. low diastolic blood pressure is associated with an increased risk of ad in the elderly population, particularly among users of antihypertensive drugs. while the reason for this finding is not clear, undetected cerebral hypoperfusion could explain the pathogenic link of hypotension to cognitve decline and ad [ ]. in the baltimore longitudinal study of aging, both hypertension and hypotension have been shown to be asso- ciated with poorer performance on tests of executive func- tion in older individuals and perceptuomotor speed and con- frontation naming among persons not receiving antihyper- tensives medication [ ]. although the collective evidence appears to support a strong relationship between hypertension and the develop- ment of ad or vad [ ], no definitive evidence has yet been presented that antihypertensive treatment is a preventive measure to cognitve decline or dementia in people with high blood pressure, and the mixed evidence obtained in the seven randomized clinical trials discussed above is a glowing example. this lack of definitive evidence must be weighed in terms of the effects of iatrogenic-induced hypotension when aggressive anti-hypertensive therapy is used. for example, a common office procedure that has received almost no clinical attention in relation to ad de- velopment may be cited. that procedure is “white coat hypertension” (wch). wch occurs when a transient and usually mild increase in blood pressure is observed in certain individuals when attending a doctors’ office. wch is not generally linked to target organ damage or prognosis from true normotensives [ ]. although there is a controversy about whether wch should be treated or not, many doctors assume mild blood pressure elevation needs to be treated, especially in the elderly. as a consequence, these individuals are given antihy- pertensives for the rest of their lives which can lower their blood pressure subnormally. it must be remembered that in the aging individual, diastolic hypotension can not only introduce cerebral hypoperfusion, but also the prospect of ad [ ]. the best way to avoid falsely treating wch is for physicians to place the new patient on the recumbent posi- tion and measure blood pressure several times during a minute visit. the other side of the coin is not treating moderate or high hypertension or preventing hypotension, and this choice can lead to cardiac and cerebrovascular complications and the threat of death. for these reasons, more studies are rapidly needed that can guide the practitioner in managing a patient with blood pressure anomalies. . heart failure heart failure is a condition in which the heart can not ade- quately pump enough blood to meet the body’s needs. it is marked by weakness, tissue edema, and shortness of breath. the most common cause of heart failure occurs from stenosis of the coronary arteries which supply oxygen to the heart. heart failure is often associated with other comorbid vascular risk factors for ad including ischemic heart disease, hypertension, and atrial fibrillation [ ]. brain hypoperfu- sion is a common outcome of heart failure [ ]. as blood flow pumped out of the heart slows down, returning venous blood to the heart backs up, causing tissue edema particularly in the lungs. heart failure is the most common reason for hospitalization among older adults [ ] and has been reported to worsen cognitive impairment [ ] and increase the risk of ad. a recent report by alves and her colleagues [ ] indi- cates that heart failure in elderly persons is associated with lowered cerebral blood flow in the posterior cingulate gyrus and the lateral temporoparietal cortex, regions that are linked to memory and visuospatial orientation. this finding is of interest since memory and visuospatial dysfunction are two of the earliest signs in imminent ad. although cbf and cog- nitive function is reduced in heart failure, this syndrome can improve following implantation of a pacemaker in patients with bradycardia or from the use of selective cardiovascular agents [ ]. clearly, aggressive treatment of heart failure to reverse brain hypoperfusion could have a significant impact in reducing the incidence of ad in these patients. . coronary artery disease (cad) coronary artery disease (cad) is the single leading cause of mortality in the united states, resulting in over , deaths annually. cad is associated with a decreased blood supply to the heart, also known as ischemic heart disease. this happens when the arteries that supply blood to the heart muscle become hardened and narrowed due to a build-up of subintimal fatty deposits called plaques. these atheromatous plaques are made up of a chemical bouillabaisse that includes cholesterol, fatty compounds, inflammatory cells, calcium, and fibrin. plaques are the basis of atherosclerosis in coro- nary, peripheral, or cerebral blood vessels. when a plaque suddenly ruptures, platelets aggregate around it inducing intraluminal thrombosis or increased narrowing of the ves- sel, a condition that can result in myocardial infarction or stroke. the use of platelet deaggregators such as aspirin and clopidogrel or cilostazol, a phosphodiesterase type inhibitor that can widen vessel lumen to increase blood flow, has been used to prevent cognitive dysfunction after intra- arterial plaque rupture. stroke and cad are known to reduce brain blood flow and potentially impair cognitive function, and both are reported to be vascular risk factor for ad [ , ]. the risk to ad could stem primarily from atherosclerotic coronary vessels that damage endothelial cells and lower the heart’s pumping ability to optimally perfuse the brain. this thinking is supported by the presence of high levels of cardiovascular psychiatry and neurology cholesterol, low density lipoprotein and triglycerides found in the blood of probable ad subjects [ ]. a number of studies are now in progress testing whether cholesterol homeostasis and lipoprotein disturbances using cholesterol-lowering statins can alter ad pathology. how- ever, the results of these studies are inconclusive and controversial with regard to the potential neuroprotective effects of statins [ ]. another approach we and others have recommended is to pharmacologically increase endothelial vascular nitric oxide, a powerful vasodilator with antithrom- botic, anti-ischemic, and antiatherosclerotic activities [ ]. . apoe allele carriers of the apoe allele may be at higher risk of cognitive decline because among other things, the presence of this gene predisposes to an increased risk of cardiovascular pathology [ ]. aside from sharing many environmental risk factors for ad and for cardiovascular disease, there appears also to be an overlap between genetic risk factors for both conditions. for example, the apoe allele, a well-studied risk factor for ad, can increase the risk of coronary heart disease by approxi- mately % [ ]. although the functional activity of apoe varies consid- erably, one association found in the baltimore longitudinal study of aging was that carriers of this genotype but not noncarriers had greater decline in cerebral blood flow in nondemented older adults [ ]. this decline in cerebral blood flow was observed in the frontal, parietal, and tempo- ral cortices, which are the common brain regions initially affected in alzheimer’s disease [ ]. . aortic stiffening aortic stiffening is associated with advanced aging and hypertension ( ribkin). there is also compelling data that links aortic stiffening in the elderly to cognitive dysfunction ( , /mehra/hanon). evidence indicates that cognitive impairment induced by damaged cerebral microcirculation can be induced by aortic stiffness [ ]. the damage to brain microvessels from aortic stiffening would occur as follows. the aorta is known to be a reservoir of pulsatile energy delivered by left ventricular ejection during systole and discharges that energy during diastole. since the aorta is normally more compliant (distensible) than the stiffer carotid arteries, it is believed to absorb the ventricular ejection and dampen pulsatile flow into the distal vasculature, a hemodynamic condition called the windkessel effect [ ]. the windkessel effect is a protective mechanism that dampens excessive transmission of pulsatile flow that can damage the cerebral microvasculature [ ]. the normal proximal aorta consequently reduces aortic-carotid wave reflection, a physiologic event called impedance mismatch, that avoids excess transmission to the cerebral arterioles and capillaries. however, during aging, hypertension, or atherosclerosis, there is a loss of elastin which provides elasticity to the aorta, markedly reducing aortic compliance with the net effect of increasing pulse pressure and systolic pressure (hyper- tension) and reducing wave reflection at the carotid arteries. this hemodynamic phenomenon is worsened in the presence of vascular risk factors [ ] (figure ). when this happens, exaggerated pulsatile flow or pulse wave velocity is transmitted to microvessels in the brain where white matter hyperintensities and damage to endothe- lial cells that participate in controlling cerebral blood flow may result [ ]. this pathologic event assumes a mech- anistic link between cerebral hypoperfusion and cognitive impairment whose primary trigger is loss of the windkessel effect [ ]. progressive increases of pulse wave velocity are theorized to result in increasing cognitive decline and eventual ad [ ]. . cardiovascular pathology begets chronic brain hypoperfusion which begets progressive cognitive decline chronic brain hypoperfusion is not a disease but a sign that cerebral perfusion is functioning improperly. cerebral blood flow is known to decline with aging and under normal circumstances in the absence of vascular disease will not result in significant cognitive loss [ ]. to appreciate the clinical importance of developing suboptimal brain blood flow during advanced aging, it is important to point out that chronic brain hypoperfusion has been reported within the last few years to be a preclinical condition to mild cognitive impairment and a most accurate indicator for predicting whether people will develop ad [ , – , ]. the vascular hypothesis of alzheimer’s disease (ad), which we proposed in [ ], has become a mother lode of interdisciplinary research involving mainly the brain, the heart, and the circulation [ – ]. the collective evidence supporting the vascular hypothesis offers the possibility of employing interventions that limit the effects of vascular risk factors on the heart and brain. this action could prevent, delay, or reverse further progression of the inherent cognitive deterioration that often precedes ad and vad [ ]. following our vascular hypothesis proposal in [ ] we observed in [ ] that conditions such as advanced aging, a former head injury, and apoe genotype became risk factors to ad by virtue of their potential to lower blood flow to the brain. since then, several dozen heterogenous vascular risk factors to ad have been reported in the literature [ , , , – ]. but, if chronic brain hypoperfusion is initially involved in ad, how does cardiovascular disease become a risk factor for ad? we believe that cardiovascular disease and the risk factors that characterize it promote brain hypoperfusion in the aging individual by inducing cerebral hemodynamic deficits and reducing blood flow to the brain through various vasculopathic pathways [ ] (figure ). one likely pathway is the further burden that vascular risk factors add to the already reduced cerebral blood flow that is present as a result of aging [ – ]. cardiovascular psychiatry and neurology this double burden on blood flow can readily lead to a neuronal energy crisis characterized by a cerebral hypo- metabolic state that can usher cognitive decline and dementia [ ]. the neuronal energy crisis is typically followed by pro- gressive neuronoglial dysfunction and eventual neuronal death. the crisis-dysfunction-death spectre begins in ische- mic-sensitive zones such as the hippocampus and specific cortical areas [ ] and will be clinically expressed initially by mild memory impairment [ ] (figure ). a relentless and progressive brain hypoperfusion can then spread to other parts of the brain where more ischemic- resistant neurons are slowly destroyed. this action is seen to spin out of control when additional cognitive impairment becomes full-blown ad. . how neuronoglial energy crisis leads to ad pathology an eloquent example of how dependent neurons and glia are metabolically coupled to regional brain blood flow is shown in a pet study using [ f]fluoro- -deoxyglucose that mapped cerebral blood flow in normal human brain. that study found that within a vascular territory, measures of cerebral blood flow and glucose metabolic rate are practically linear [ ]. moreover, this study revealed that the cerebel- lum, despite its significantly lower metabolic activity relative to the hippocampus, is as richly perfused as the hippocampus [ ]. this finding is strikingly compelling in explaining the subcellular changes and markers of damage that occur in the hippocampal neurons but not in the less-active cerebellar neurons prior to ad. what may occur here is that a neurono-glial crisis begins to build up following chronic brain hypoperfusion which in time is expressed by abundant deposition of amyloid-beta containing plaques (abeta) and neurofibrillary tangles (nfts) in the hippocampus (an area critical for learning and memory) but basically spares the cerebellum, even at an advanced stage of ad. this difference between abundant ad lesions in the hippocampus but not in the cerebellum is dependent on the separate metabolic activity discharged by each neuronal population and the fact that energy supply and demand is greater in the hippocampus than in the cerebellum. these diverging metabolic activities expressing neuronal death markers in the hippocampus but not in the cerebellum may be due to two pathologic events occurring prior to ad neurodegenera- tion. the first pathologic event explains how cardiovascular disease is capable of inducing brain hypoperfusion and become an ad risk factor during aging. although energy consumption is much greater in the hippocampal neurons than those in the cerebellum, the glucose energy supply is similar to both neuronal populations. however, while the cerebellum is allowed to keep its neurons well-fed energeti- cally, even when glucose delivery is reduced due to cardio- vascular insufficiency, the hippocampal neurons struggle to survive with the same glucose deficiency that is parsimon- iously available to all neurons from the hypoperfused state. this selective brain cell energy crisis is the direct result of blood flow supply not meeting energy demand in highly metabolically active neurons whose vascular reserve capability has reached its limits from persistent cerebral hypoperfusion [ ]. at this stage, hippocampal and cortical neurons undergo oxidative and endoplasmic reticulum stress that provide less atp, the main energy fuel for cells [ ], necessary to maintain normal function required for cell sur- vival. this activity negatively affects posttranslation proces- sing steps resulting in impaired protein transport, synthe- sis, assembly, and folding. defects occurring during their synthesis, assembly, or folding can compromise the normal intracellular and extracellular secretory transport pathway, threatening brain cell survival that results in progressive cognitive decline [ ]. a fundamental principle in cell biology is seen by the use of chemical energy in the form of atp to assemble, dis- assemble, and alter protein structure. since proteins do most of the work to keep neurons healthy, their proper production and folding are crucial for normal behavior, particularly involving learning and memory. protein misfolding is a pro- cess in which proteins are unable to attain or maintain their biologically active shape [ ]. most proteins require assist- ance from molecular chaperones for proper folding [ ]. these chaperones are specialized proteins which protect other unfolded proteins from misfolding and clumping (aggregating) together extracellularly (figure ). although protein folding is thought to be a spontaneous process not requiring energy input from nucleotide triphosphates [ ], the steps leading to it, involving transcription, translation, and protein synthesis, are energy dependent [ , ]. given the complexity of the folding process, it is not surpris- ing that things can go wrong particularly in the presence of reduced cerebral perfusion and lowered energy substrate del- ivery during advanced aging. defects occurring during protein synthesis, assembly, or folding can compromise the normal intracellular and extra- cellular secretory transport pathway, threatening brain cell survival that results in progressive cognitive decline [ ]. protein cleavage abnormalities and reduced degradation of oxidized proteins by the ubiquitin-proteasome pathway may facilitate bace- expression, the proteolytic enzyme responsible for generating abeta peptide [ ]. this process could also downregulate bace- , the enzyme that cleaves β- amyloid precursor protein at a site that prevents abeta pro- duction [ ]. other subcellular aberrations from reduced atp synthesis include (among other things) neurotransmit- ter failure, free radical production, na+-k+ atpase pump dysfunction, lower trophic/growth factor uptake, and faulty motor-protein transport within microtubules. this time- bound subcellular corruption climaxes with synaptic loss and neuronal death [ ]. the second pathologic event explains why there is a scar- city of amyloid plaques and nfts in the cerebellum while substantial aggregation is seen in the hippocampus of ad brains. during chronic brain hypoperfusion, the cerebellum enjoys all the glucose it needs to supply its less energy- consuming neurons, while the energy-starved and highly active hippocampal neurons undergo progressive subcellular changes due to their greater demand for energy supply. cardiovascular psychiatry and neurology this energy supply/demand inequity consequently leads to the start of a neurodegenerative process involving the for- mation of intracellular-extracellular aß and axonal nfts in the hippocampal region while mostly sparing the cerebellum. the neuronal bias that generates an unequal energy crisis in brain regions of high metabolic demand such as the hippocampus and lower metabolic activity such as the cere- bellum is a testament to the argument that amyloid plaque aggregation is a product (not a cause) of selective neuronal energy failure [ , ]. supporting this conclusion are studies by us [ , , ] showing that after chronic brain hypoperfusion in aging rats, memory loss, and a select- ive reduction of cytochrome oxidase, reflecting lower atp activity, was found uniquely in the ca region of the hip- pocampus and in the posterior parietal cortex, two regions associated with memory function and the initial targets of ad neurodegeneration [ , ]. a more detailed description of this neuronal energy crisis inequity can be found in our previous publications [ , , , , ]. finally, much confusion has been generated surrounding the terms cerebral hypoperfusion and cerebral ischemia, when they have been used interchangeably in the literature. to avoid this confusion, the term cerebral hypoperfusion should be used to describe the relatively slow pathologic process involving months or years when brain perfusion is not com- mensurate with neurometabolic demand. conversely, cere- bral ischemia should refer to the more rapid pathologic pro- cess involving hours or days of sudden blood flow reduction that is capable of killing or damaging brain cells in the epi- center of the ischemic lesion and often allows the formation of a penumbral region made up of undamaged but inactive or “idling” neurons [ ]. this definition of hypoperfusion and ischemia is useful in trying to explain the “slow” from the “fast” cognitive decline seen after either event, resulting for example, from the presence of long-term vascular risk factors (hypoperfusion) or a sudden stroke (ischemia). . slowing ad prevalence can anything be done to slow down the total number of new ad cases expected in the next few decades? in our judgment [ – ] and those of others [ – , – ] and in the absence of finding a rapid cure for this dementia, preventive measures to lower the prevalence rate of ad (and by default, vad) through the management of potential or actual risk factors is a reasonable clinical stra- tegy. a structured clinical approach can be employed for this purpose. it requires the diagnostic detection of cardio- vascular disease and assessment of warning signs for stroke in elderly individuals (> years) who show or complain memory difficulties during clinical examination. it should be noted that ischemic heart disease or ischemic stroke are not the sole vasopathogenic triggers of ad. many other vascular-related risk factors that increase the burden of age- related cerebral hypoperfusion also appear to accelerate the development of alzheimer dementia, and these have been reviewed in other publications [ – ]. this is a theme that has not received wide-attention in the medical literature despite its obvious importance. based on cross-sectional and longitudinal epidemio- logic studies involving mostly elderly subjects, a variety of cardiovascular-related risk factors to ad have been reported. these include high serum lipid/cholesterol levels, high serum homocysteine, body-mass index, smoking, physical inactivity, unhealthy diet, hypertension, hypotension, and metabolic syndrome [ ]. comorbid presence of two or more such risk factors tends to increase the probability of acquiring ad [ ]. when any or several of these risk factors, are discov- ered during clinical examination, the physician should be suspicious of actual or impending structural heart damage. structural heart damage may involve aortic or mitral valve thickening, chronic valvular regurgitation, left ventricular wall motion abnormalities, ventricular filling defects, and left ventricular hypertrophy. structural heart damage can reduce cardiac output and ejection fraction (or cardiac index) thus directly affecting cerebral perfusion [ , ]. in addition, cardiac damage resulting in hemodynamic pump dysfunc- tion can be the source of ischemic stroke or cerebral hypoper- fusion [ , ] which in the elder population frequently evolves into cognitive impairment [ ] and possible con- version to ad or vad. many of these cardiac risk factors, however, can be cor- rected or treated successfully if identified in time [ ]. for example, high blood pressure is a major risk factor for stroke and for heart failure and as we have noted, is also closely correlated with cognitive decline and dementia. its treatment with anti-hypertensive drugs in the elderly has been shown to reduce cognitive decline and dementia [ ] and to partially counteract the risk of heart failure on demen- tia [ ]. the heart-brain connection to memory function can be appreciated from experimental data on rodents. we reported that during exposure to chronic brain hypoperfusion in aged rats, vulnerable brain cells initially undergo a hypometabolic state that reduces memory function while neurons remain structurally intact [ ]. even after memory impairment is induced in these aged rats, the metabolically-compromised neurons can return to a normal state if and when cerebral perfusion is restored after weeks following brain hypoper- fusion [ ]. these findings indicate two important points: ( ) that cerebral hypoperfusion in these rodents can induce a hypometabolism that impairs memory function without killing the neurons, and ( ) that neuronal rescue of the hypoperfused brain cells can be achieved even after a lengthy (by rat standards) period of reduced brain blood flow. if this rat model is indicative of that which may occur in elderly humans who develop chronic brain hypoperfusion prior to ad, a therapeutic target focusing on brain blood flow insufficiency could be a major breakthrough. the notion of neuronal rescue from the hypoperfused state is supported by clinical findings in human brain [ , ]. it is also pertinent to note that brain hypoperfusion induced by cardiac pathology can promote not only vad but also ad since these pathologic states pose important risk factors to both dementias [ ]. cardiovascular psychiatry and neurology . conclusions we have attempted to show in the present paper the associa- tion between chronic brain hypoperfusion and cardiovascu- lar risk factors of ad in a crystallized fashion pointing out the major problems associated with cardiovascular pathology, cerebral hypoperfusion, and development of ad. cerebral hypoperfusion following cardiovascular pathology during aging is a much neglected research topic in ad that deserves greater attention. it is crucial to note that cardiovascular risk is generally present prior to ad and that ad neurodegenerative lesions such as abeta and nfts are not essentially considered pre- cursors or triggers of heart disease but may be more a mani- festation of the neuronal energy crisis provoked by vascular risk factors to dementia. the findings lend support to the design of therapeutic targets aimed at preventing chronic brain hypoperfusion and its consequential neural hypometabolism prior to the onset of cognitive symptoms or neuropathology during normal aging. the therapeutic blueprint will largely depend on early detection of low cerebral blood flow in asymptomatic indi- viduals who present cardiovascular risks factors associated with progressive cognitve 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[ ] k. g. mawuenyega, w. sigurdson, v. ovod et al., “decreased clearance of cns β-amyloid in alzheimer’s disease,” science, vol. , no. , p. , . editorial ann neurosci ; : – ian conference in odisha sushant kaushal a gurkeerat kaur a abdul ghani b navneet kaur d paul bali c akshay anand a a department of neurology, neuroscience research lab, postgraduate institute of medical education and research, chandigarh, india; b department of histopathology, postgraduate institute of medical education and research, chandigarh, india; c department of biophysics, panjab university, chandigarh, india; d department of physical education, panjab university, chandigarh, india published online: september , akshay anand, phd neuroscience research lab, department of neurology postgraduate institute of medical education and research chandigarh (india) e-mail akshay anand @ rediffmail.com © s. karger ag, basel e-mail karger@karger.com www.karger.com/aon doi: . / the xxxv annual meeting of indian academy of neurosciences was held from october to , in cuttack, odisha. the theme of the meeting was “trans- lational neurosciences and its application in protection of mental health”. the students from neuroscience re- search lab, pgimer chandigarh participated in this workshop and gathered knowledge from the talks of dif- ferent neuroscientists. on the first day, that is, october , all ian members gathered near the auditorium, and attended the welcome address by dr. lipika patnaik and dr. tisa from kyoto university. dr. n.r. jana from nbrc, manesar present- ed her research paper in which she explained the rescue of altered protein homeostasis in a mouse model of hun- tington’s disease. in the evening address, the lecture of dr. s.k. trigun was held on the subject “sirtuins and epi- genetic pathogenesis of excitotoxic brain disorders” in which he concluded that the activation of sirt- and sirt could be a relevant strategy to ameliorate tnf-α led ex- citotoxic neurodegenerative condition in the rat brain. the results demonstrate that the declined level of sirt- in the cerebral cortex and cerebellum associates with the neuroinflammation o(tnf-α and nfκb) led he patho- genesis reflected by the transition of neuroprotective nr /nr a pro-inflammatory factors, neurodegenera- tive combinations of nmdar composition towards a neurodegenerative nr /nr b combination. dr. a. chattopadhay, from ccmb, hyderabad, described the interaction of membrane cholesterol with g protein coupled receptor in which the dependency of serotoni- n a receptor with the ph, ionic strength and tempera- ture was found to enhance the interaction of brain cho- lesterol. in that context, they reported the presence of cholesterol recognition/interaction amino acid consen- sus motifs in the seotnin a receptor. they also showed the utilizing homo-fret that the serotonin a receptoris constitutively oligomerized in live cells, with the possibil- ity of higher order oligomers of the receptor. the talk by dr. deepak kumar sarkar that “alcohol induced epigen- etic modifications of stress regulatory genes transmit via germilne” was discussed. he showed that the effect of al- cohol in the epigenetic modulation of pomc gene led to the transgenerational increase in the level of stress hor- mones. they have created different mice models to analyse this study; in a result they found that maternal alcohol feeding significantly affects the pomc gene kaushal/kaur/ghani/kaur/bali/anandann neurosci ; : – doi: . / methylation, gene expression and pomc endopheno- types. these findings show that alcohol-induced changes in some of the epigenetic machinery are transmitted across generations via germline. dr. k.p. mohana kumar from iucbr, kottayam, talked about mitochondrial neuronal cell lines: cre- ation, characterization and validation as cellular mod- els of neurological diseases. cell lines were created as a model to mimic neurological diseases like parkinson dis- ease from human cells by cybrid formation and they have checked the absence or presence of mitochondrial energy crisis in neurodegenerative disorders. they have created cells from the human neuroblastoma cell lines, which show changes in the expression of several mitochondrial genes, decline in mitochondrial respiratory activity, de- creased membrane potential and altered morphology. apart from that, they have created the autism spectrum disorders and attention deficit hyperactivity disorders cy- brids and demonstrated the absence or presence of mito- chondrial energy crisis in these orders to make these suit- able for drug screening against the diseases and to estab- lish the usefulness of this cellular model for studying mitochondrial dysfunctions of various neurological dis- orders. dr. s.c. bose chinnathambi from ncl, pune, spoke on “microglial internalization and post-transla- tional modifications of tau” explaining tau as a patho- logical feature in ad, its propagation and internalization by microglia, he showed cell co-culture by adding tau in monomeric and aggregated form to study internalization by microglia and its toxicity. the study concluded that small length aggregates are more toxic than long length tau. dr. pankaj seth demonstrated that the cellular and molecular mechanism mediated by astrocytes involved hiv- neuropathogenesis. they explored the cellular and molecular mechanisms of astrocyte-mediated neuro- nal damage by studying the role of atp-mediated neuro- nal damage in primary cultures of human brain cells and validated the in vitro findings in autopsy brain sections of  aids patients. their cell culture study showed that vdac- in astrocytes releases atp as gliotransmitter and mediate neuronal damage. the talk by rv omkumar from rgcb, thiruvanathapuram, explained the role of cam kinsae ii in learning and memory using in-vitro study to understand its biochemical and structural regu- lation by its ligand glun b, which causes the dephospho- rlyation of camkii. they have used cam kinaseii in such an in vitro system to understand its biochemical and structural regulation by its ligands, the nmda receptor subunit, glun b. they found that camkii is allosteri- cally modulated by glun b. mutants of camkii, e a and h a were used as tools to test the role of allosteric modulations of camkii under physiological conditions. sunita mittal from aiims, rishikesh, presented her research work on memory and its opponent alzheimer’s disease, in which she described memory, its types, pro- cessing, amnesia and diagnosis of ad in csf, marker us- ing imaging techniques. in another lecture, dr. a.b. pant, iitr, lucknow, showed the efficacy of induced pluripo- tent stem cells (ipscs) in the developmental neurotoxic- ity. his talk on “in vitro models of developmental neuro- toxicity: a journey with human cord blood stem cells” represented -d and d cultures of ipscs. he character- ized various cells in-vitro and in-vivo for ipscs and es- tablished d organoid structures to be used as a model for drug testing. parul bali, from panjab university, had her poster session at late afternoon on “optimization of am- yloid β dose for establishing memory deficit mouse mod- el of alzheimer’s disease”. a workshop was held by a neu- ro-artist mr. vinod mehta in order to sensitize the scien- tific community towards science – arts convergence and its role in managing neuronal disorders. on october , we attended the lecture of dr. serge picaud, paris, on visual restoration by retinal prostheses and optogenetic therapy in non-human primate models. he discussed new photovoltaic retinal implants and op- togenetic therapy on non-human primates to improve further current strategies for restoring vision. dr. s.k. hota, dihar, leh-ladakh, presented his talk on im- proving neurovascular coupling to ameliorate hypobaric hypoxia-induced cognitive impairment. then, the talk started on “perturbed stress granules dynamics in motor neuron diseases” by dr. u.b. pandey, pittsburgh, in which he discussed the role of protein fus linked to both famil- ial and sporadic forms of als. we also attended the lecture of dr. p. srivastava from iiit, hyderabad, who presented the difference in male and female in making sense of desktop -degree vir- tual space. they found variable response in different sex- es and related this with hormonal levels of testosterone. they also examined the interaction between gender type and interaction type. dr. t.c. nag, aiims, new delhi, presented the effect of iron overload and its consequence with age in retinal structural alteration and expression of iron regulatory proteins. it was found that iron accumulated with age, re- sulting in phagosome accumulation in rpe, damaged photoreceptors, thinning of outer segment and increased tunnel positive cells. in the next lecture, dr. t. srivas- tava from the university of delhi explained the epigenetic ian conference in odisha ann neurosci ; : – doi: . / regulation of glioma stem cell biology in the hypoxic mi- croenvironment. the cancer stem cells, which are in few proportions in cancer cells, are found to be in hypoxic condition that causes cells to be in a demethylated state, leading to an exacerbated expression of oct- and nanog. dr. r. pal from tifr, bengaluru, described the role of hu- man ipsc for disease modelling and treatment of age-re- lated macular degeneration. he used ipsc cell culture and differentiated rpe cells with prominent morphology that is, cilia processes and melanosomes. functional analysis was done by calcium response and electrophysiological responses. the poster session was held from : to : pm near pillars of wisdom. sushant kaushal received appreciation from scientists for his work on validation of thesis data. abdul ghani and gurkeerat kaur presented a talk on yoga and its benefits in different diseases. they were also applauded by scientists and students. october st, which was the last day of conference, started with a talk by dr. anita jagota on “biological clock dysfunction in aging and parkinson’s disease”. in her talk, she discussed her studies on purturbances in the func- tional integrity of circadian system with the neural degen- erative changes in aging and rotenone-induced parkin- son’s disease rat model. stoichiometric alterations ob- tained in the levels in the genes such as bmal , per , cry and cry were observed. proteome analysis using maldi tof/tof in relation to locomotor activity profiles has led to the identification of candidate biomarkers of aging and neurodegeneration, which will help in targeting nov- el treatments of circadian dysfunction for age-induced disorders and pd. the lecture of dr. t.s. roy, aiims, new delhi on the topic “age-related changes in the ex- pression of glutamic acid decarboxylase (gad ) and nmda receptor (nmda-r ) in the human inferior col- liculus and another scientist dr. k.k. barhwal, aiims, bhubaneswar, on the topic entitled salidroside as a poten- tial pharmacological molecule for treatment of hypoxia induced neurodegeneration was delivered where he dis- cussed the therapeutic effect of salidroside on various neurodegenerative diseases. overall, it was a unique experience. the conference enhanced our knowledge in neuroscience, which includ- ed latest researches and advancement in its techniques. we also got an opportunity to meet different scientists from all over the world and were able to understand their research in this field. disclosure statement the authors declare that they have no conflicts of interest to disclose. [pdf] renewable methane from anaerobic digestion of biomass | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /s - ( ) - corpus id: renewable methane from anaerobic digestion of biomass @article{chynoweth renewablemf, title={renewable methane from anaerobic digestion of biomass}, author={d. chynoweth and j. m. owens and r. legrand}, journal={renewable energy}, year={ }, volume={ }, pages={ - } } 	d. chynoweth, j. m. owens, r. legrand 	published 	environmental science, engineering 	renewable energy production of methane via anaerobic digestion of energy crops and organic wastes would benefit society by providing a clean fuel from renewable feedstocks. this would replace fossil fuel-derived energy and reduce environmental impacts including global warming and acid rain. although biomass energy is more costly than fossil fuel-derived energy, trends to limit carbon dioxide and other emissions through emission regulations, carbon taxes, and subsidies of biomass energy would make it cost… expand view via publisher maaz.ihmc.us save to library create alert cite launch research feed share this paper citationshighly influential citations background citations methods citations results citations view all figures and tables from this paper 	 table 	 figure 	 table 	 table 	 table 	 table view all figures & tables citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency renewable biomethane from land and ocean energy crops and organic wastes 	d. chynoweth 	environmental science 	 	 	pdf 	view excerpts, cites methods and background save alert research feed production of methane and hydrogen from biomass through conventional and high-rate anaerobic digestion processes 	b. demirel, p. scherer, o. yenigun, t. onay 	chemistry 	 	 save alert research feed conversion of biomass to methanol and ethanol 	g. devi, s. chozhavendhan, j. jayamuthunagai, b. bharathiraja, r. p. kumar 	environmental science 	 save alert research feed anaerobic treatment of agricultural residues and wastewater - application of high-rate reactors 	w. parawira 	materials science 	 	 	highly influenced 	pdf 	view excerpts, cites background save alert research feed optimization of dry anaerobic fermentation of solid organic wastes 	j. a. kumar, j. li, j. he, sheng chang, a. jha 	materials science 	 	 	view excerpts, cites background save alert research feed sustainable production of biogas from renewable sources: global overview, scale up opportunities and potential market trends 	l. e. montañez-hernandez, inty omar hernández-de lira, gregorio rafael-galindo, maría de lourdes froto madariaga, n. balagurusamy 	environmental science 	 	 save alert research feed anaerobic digestion as an effective biofuel production technology 	serge r. guiot, jean-claude frigon 	environmental science 	 	 save alert research feed plant biomass as an energy efficient feedstock in the production of renewable energy 	a. salter, l. holiday, c. banks, m. chessire, r. mulliner 	engineering 	 	 	view excerpt, cites background save alert research feed enhanced anaerobic digestion of biomass waste for optimized production of renewable energy and solids for compost 	m. albertson, a. pruden, r. t. oliver 	materials science 	 	 save alert research feed optimization of biogas production by anaerobic digestion for sustainable energy development in zimbabwe 	r. jingura, r. matengaifa 	engineering 	 	 save alert research feed ... ... references showing - of references biochemical methane potential of biomass and waste feedstocks 	d. chynoweth, c. turick, j. m. owens, d. jerger, m. w. peck 	environmental science 	 	 save alert research feed environmental impact of biomethanogenesis 	d. p. chynoweth 	environmental science, medicine 	environmental monitoring and assessment 	 	 	view excerpt, references background save alert research feed methane from biomass systems analysis and c abatement potential 	r. legrand 	chemistry 	 	 	view excerpts, references background save alert research feed a preliminary assessment of carbon dioxide mitigation options 	d. spencer 	economics 	 	 	view excerpt, references background save alert research feed seaweed cultivation for renewable resources 	k. bird, p. benson 	environmental science 	 	 save alert research feed anaerobic digestion of biomass 	d. chynoweth, r. isaacson 	chemistry 	 	 	view excerpt, references background save alert research feed biogas generation from community-derived wastes and biomass in the us 	paper presented at the tenth annual energy-sources technology conference and exhibition, 	 related papers 	abstract 	figures and tables 	 citations 	 references 	related papers stay connected with semantic scholar sign up about semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue multiple input productivity indexes robotica ( ) volume , pp - news note multiple input productivity indexes* keith e. mckee iitrl manufacturing productivity center chicago, illinois (usa) (received: january , ) for several years the american productivity center (apc) has been publishing an index under this title. the most recent issue, volume , number , dated november , is a valuable source of data that should be obtained and reviewed by all of those interested in productivity. this short article uses data from that publication with views and opinions added by myself. the cover of this report contains the following data on productivity changes. period is included. it is interesting to note that only six economic sectors have experienced a decrease in productivity over the two periods considered: • petroleum with a . % decrease in - and a . % decrease in - . it is interesting to note that total factor productivity has decreased significantly since the energy crisis of . does this imply that the petroleum industry has since then been working with less desirable input materials, or does it indicate that in a period of rapidly rising energy costs there has been little attention to improving productiv- ity? it might be noted that the situation has worsened from - to - . • mining has decreased by . % in - and . % in - . presumably these decreases are related to en- productivity growth rates (annual percent of change) private business economy segments: farming manufacturing non-farm/non- manufacturing sectors: goods-producing services-producing total factor productivity . % - . . . . . labor productivity . % - . . . . . capital productivity . % - . . . . . capital/labor ratio . % - . - . . - . . as often mentioned in previous issues of frontiers, we seri- ously question productivity changes over a short period as having much significance (and we consider a year to be a short period). this table offers a particularly good example - based on this table farming is clearly the major problem within the u.s. economy. for a variety of reasons this is not at all true and conclusions reached by considering only data can be very misleading. this table again illustrates that total factor productivity does not provide insight much different than that provided by the more traditional labor productivity growth rates. there is a broad belief that somehow total factor data are much more meaningful and it may well be, but only occasionally do the trends differ significantly. it may be better to use total factor productivity but, in general, little understanding is lost if only labor productivity data are available and used. other details are excerpted from table ilia in the report. this is the total factor productivity based on average annual rate of change for - and - . overall a -year * reprinted from manufacturing productivity frontiers , no. - january, , by kind permission of the iit research institute, chicago, illinois (u.s.a.) vironmental and safety requirements that have made it more difficult to mine. here there is an improvement (at least a lessening of the negative total factor productivity growth). construction has decreased . % in - and . % in - . construction has long had a productivity problem (it decreased . % annually between and ). a variety of explanations have been offered for the long-term decrease in construction productivity. frankly none of these are totally satisfactory and this remains at least to this author, an unanswered question and we do not even have a hypothesis we can believe. primary metals total factor productivity decreased % in - and . % in - . this represents a long-term problem and one which has impacted on the international competitiveness of this industry. there is a broad perception that this industry has failed to emphasize productivity and so brought this decrease on itself. within the past few years this industry has been hit by a decrease in demand and a worldwide excess capacity. finance and insurance shows a decrease of . % in - and . % in - . in a growth industry where there has been a major introduction of computers, this decrease is almost unbelievable. does someone have an explanation? https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core news note • public utilities saw a . % decrease in - and a . % in - . again this decrease started with the energy crisis and the questions raised relating to the petroleum industry are relevant. thus far we have looked at the negatives and that is really unfair. many sectors of the economy have done well. approxi- mately three times the sectors have shown total factor produc- tivity in both periods as the number that shows negative. comments on each would be boring and this writer is incompe- tent to do so in any case. a few sectors are considered below. farming increased . % in - and . % in - . perhaps after decades of productivity improvement, productiv- ity in farming is going to plateau. u.s. farmers are approxi- mately twice as productive as those in france and england and four times those in germany and japan. our earlier comments on the dangers of using short term productivity measurements are clearly illustrated by this example. the performance for the farming sector would appear to be an anomaly— certainly to be ignored until and unless there is a continuation of this one-year trend. • textiles ( . % and . % increases) and apparel ( . % and . %) have a long-term history of productivity improvement and have been able to remain competitive with producers in other nations. • electrical machinery with . % and . % increases repres- ents another industry which has improved productivity over the long haul and has by-and-large managed to remain competitive with foreign companies. u.s.a. with excellent, effective communication. by-and-large these increases demonstrate the impact of ever-improving technology. • trade with . % and . % increases represents improve- ments in a sector of the economy which has shown long-term improvement. productivity growth rates always represent an interesting set of data. the interpretation of the data is even more interesting because the same data can be interpreted in different ways based on the bias and background of the writer. the data used in this paper are taken from the apc report referenced earlier. our thanks to apc —this is a useful report and one of considerable value. we hope that some of our readers will obtain the report and we would be interested in alternative interpretations. https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core book summer .qxd assessing u.s. energy policy article (published version) http://sro.sussex.ac.uk brown, marilyn a, sovacool, benjamin k and hirsh, richard f ( ) assessing u.s. energy policy. daedalus, ( ). pp. - . issn - this version is available from sussex research online: http://sro.sussex.ac.uk/id/eprint/ / this document is made 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url is given for the original metadata page and the content is not changed in any way. http://sro.sussex.ac.uk/ for decades, our political leaders have told us that we need to use energy more ef½ciently and derive more of it from domestic sources. since the energy cri- sis of , u.s. presidents have declared the need to gain independence from un- stable foreign energy suppliers and to do so with the same moral fortitude as if ½ghting a war. some politicians have proposed massive government programs to achieve the goals of their energy poli- cies; others have sought to unleash free- market forces that would encourage companies to develop novel sources of energy and motivate consumers to use energy more wisely. despite more than three decades of such efforts, the united states has not achieved the goal of energy indepen- dence. while progress in adopting more energy-ef½cient technologies has saved billions of dollars throughout the econo- my, most other indicators of energy au- tonomy–such as the percentage of im- ported fuel–demonstrate that the coun- try has become less independent than ever. president bush acknowledged this fact in his recent state of the union ad- dress, telling americans that the coun- try has become “addicted to oil” and urging citizens to ½nd alternative ways to satisfy their energy needs. for those with a sense of history, bush’s clarion call sounded eerily familiar. even though energy ef½ciency has tak- en root in some sectors of the economy, dædalus summer marilyn a. brown is interim director of oak ridge national laboratory’s engineering science and technology division. an expert on the com- mercialization of new energy and environmental technologies and the evaluation of government programs and policies, she has authored more than publications. benjamin k. sovacool is a eugene p. wigner postdoctoral fellow at the oak ridge national laboratory. through the national science foun- dation’s electric power networks ef½ciency and security program, he has investigated the social impediments to distributed and renewable energy systems. richard f. hirsh is professor of history and sci- ence & technology studies at virginia polytech- nic institute and state university. the author of “technology and transformation in the ameri- can electric utility industry” ( ) and “power loss: the origins of deregulation and restruc- turing in the american electric utility system” ( ), he currently manages virginia tech’s consortium on energy restructuring. comment by marilyn a. brown, benjamin k. sovacool & richard f. hirsh assessing u.s. energy policy © by the american academy of arts & sciences the authors are grateful to oak ridge na- tional laboratory (operated by ut-battelle, llc, for the u.s. department of energy) and the national science foundation for supporting elements of the work reported here. any opin- ions, ½ndings, conclusions, or recommenda- tions expressed in this material are those of the authors and do not necessarily reflect the views of oak ridge national laboratory or the na- tional science foundation. it has not compensated for the growth in energy consumption that has occurred since , nor will it (if current trends continue) accommodate the growth that forecasters anticipate in coming decades. moreover, america’s depen- dence on oil from insecure or politically unstable countries has required exten- sive diplomatic and military efforts that incur huge costs borne by energy users and taxpayers. today’s information economy also remains inextricably tied to reliable power and to just-in-time manufacturing and distribution process- es that depend on fleets of petroleum- guzzling trucks and airplanes. disruptions in increasingly fragile energy systems can cause havoc to the nation’s economy and to everyday life. we have already had a taste of such dis- ruptions in the form of the california electricity crisis of to , the northeast blackout, and the fuel- supply interruptions resulting from the gulf coast hurricanes in . these disruptions may be trivial preludes to what could be more substantial future catastrophes. indeed, the country faces at least ½ve immense and interconnected energy challenges due to ( ) the risk of oil-supply disruptions; ( ) increasing electricity usage; ( ) a fragile electric- power (and overall energy) infrastruc- ture; ( ) the lack of sustained efforts to push energy-ef½ciency practices; and ( ) the growing environmental impacts of increasing energy consumption. first, the united states remains vul- nerable to the risk of oil-supply disrup- tions, despite plenty of warnings over the past three decades. in the arab members of the organization of petro- leum exporting countries (opec) or- chestrated an oil embargo, the ½rst sup- ply disruption to cause major price in- creases and a worldwide energy crisis. in unadjusted terms, the price of oil on world markets rose from $ . per barrel in september to $ . per barrel in december . further price hikes and economic repercussions accompanied the iranian revolution in . eleven years later–in –when iraqi forces invaded kuwait, opec controlled rough- ly . million barrels per day (mbd) of spare capacity, enough to replace the oil from the combatant countries and to supply about percent of global de- mand. even so, the elimination of iraqi and kuwaiti shipments contributed to oil prices jumping from around $ . per barrel in january to $ . in february . in , opec’s spare production ca- pacity stood at only percent of world demand, with roughly percent of this spare capacity located in saudi arabia. the rapidly growing demand for oil by china and india to fuel their expanding economies has placed unprecedented pressure on the world supply of oil, lead- ing to recent prices of crude oil at $ per barrel and higher. because spare pro- duction capacity is both extremely limit- ed and concentrated in one volatile re- gion, world oil markets remain vulnera- ble to short-term disruptions. this situa- tion will not likely improve since almost half of the world’s proven reserves of conventional oil are in saudi arabia, iraq, and iran. the united states remains more sus- ceptible today to oil-supply disruptions and price spikes than at any time in the recent past. it has grown to become the world’s largest oil consumer by a consid- erable margin while its domestic oil pro- duction has rapidly diminished. oil im- ports have ½lled the expanding gap and accounted for percent of total u.s. oil consumption in –up from per- cent in . to obtain a sense of the consequences of a disruption in a constrained world dædalus summer comment by marilyn a. brown, benjamin k. sovacool & richard f. hirsh oil market, the national commission on energy policy, a bipartisan group of six- teen leading energy experts, simulated an ‘oil-supply shockwave’ in . un- rest in oil-producing nigeria, an attack on an alaskan oil facility, and the emer- gency evacuation of foreign nationals from saudi arabia precipitated the imagined shockwave, which removed three mbd from the world’s market of oil. as result of these events, the price of gasoline in the united states rose to $ . per gallon, two million americans lost their jobs, and the consumer price index jumped percent. worse, pan- elists who participated in the study con- cluded that we could do nothing to avoid these impacts after the hypothetical dis- ruptions began. the stagnating fuel economy of cars has contributed to america’s vulnerabil- ity to oil disruptions. corporate average fuel economy (cafe) standards for cars peaked in at . miles per gallon. for the past two decades, consumer (and manufacturer) preferences for larger and more powerful autos have negated tech- nological advances in front-wheel drive transmissions, electronic fuel injection, enhanced power-train con½gurations, and computer-controlled engines, which would improve gas mileage even if noth- ing else were changed in cars. new-vehi- cle fuel economy therefore remains no higher today than in , but automo- bile weight has increased by percent and horsepower has almost doubled. in addition, more cars populate the roads, and are driven more miles each year. the net result of these trends has been grow- ing demand for oil in the transportation sector and greater imports to meet that demand. second, the united states continues to see increasing demand for electricity in a way that threatens its ability to produce it. the country consumed about per- cent more electricity in than it did in , with power usage growing from percent of the nation’s total energy use in to percent in . and this demand for electricity will continue to grow: the energy information admin- istration forecasted in that electric- ity use will increase at a rate of . per- cent annually through . though much lower than the percent annual growth rate experienced before the energy crisis, the current rate would still require a doubling of electricity produc- tion in about thirty-seven years. increased demand for power in the past decade has been met almost exclu- sively through the use of quickly built and increasingly ef½cient natural-gas combustion turbines or combined-cycle equipment. indeed, more than giga- watts (gw) of gas-½red power genera- tion have been added to the power grid between and , which totaled about , gw for the nation in . despite the high price of this clean- burning gas in the last few years, its use in new power plants seems likely to in- crease. but energy analysts see problems with this trend. the national petroleum council predicts that current north american sources will be able to satisfy only percent of domestic demand for natural gas. questions of security will likely emerge as the trend of natu- ral-gas imports begins to emulate the increasing trend of petroleum imports. aggravating this concern is the possi- bility that today’s nuclear-power plants could be retired over the next ½fty years as current licenses expire, depriving the nation of one of its key noncarbon ener- gy sources and pushing up demand for natural gas if that fuel replaces nuclear energy for electricity production. what about other sources of power? coal’s high carbon content and added dædalus summer assessing u.s. energy policy cost of pollution abatement will con- tinue to pose challenges for power pro- viders. clean coal technologies such as integrated gasi½cation combined cycle and fluidized bed combustion offer policymakers a way to capture concen- trated streams of carbon dioxide, but they still remain years away from com- mercial viability. because of security problems related to fuel sources and waste disposal, as well as potential pub- lic opposition, new nuclear technology also cannot be counted on for wide- spread near-term use. and despite some impressive federal and state efforts to promote them, non-hydro renewables (such as biomass, geothermal, wind, and solar) have gained only a percent share of electricity generation over the past thirty years. reductions in the cost of power produced from renewables in this time have been impressive, making them look increasingly attractive for fu- ture use. yet the intermittence of renew- ables–especially the most cost-effective wind turbines–coupled with high capi- tal costs, a host of lingering utility-mo- nopoly rules, and public opposition to local siting will likely prevent such tech- nologies from taking over the bulk of the generation burden, at least in the next thirty years. overall, it appears that meeting future demand for electricity will become an increasingly arduous un- dertaking. third, the electric-power-transmission infrastructure remains precarious and brittle, despite its increasing use. data from the edison electric institute and the electric power research institute note that utility investment in transmis- sion peaked at almost $ billion in , but declined to an inadequate level of $ . billion in (in dollars). spending grew to $ . billion in and $ . billion in , though many analysts still feel more investment is necessary to transmit power to the grow- ing wholesale and retail markets that have been created since utility-industry restructuring began in the s. but much higher spending may not be forthcoming, given that (as noted in a rand corporation study) incen- tives in the partially deregulated utility industry favor minimal investments in transmission facilities. because federal regulators generally limit rates of return on transmission investments, compa- nies often prefer to construct and oper- ate new generation facilities, whose un- capped rates of return depend only on market conditions. to complicate mat- ters more, local opposition to new pow- er lines has grown over the years as the country has become more populated, re- sulting in delayed construction (or can- cellation) of some transmission facili- ties. taken together, these trends have resulted in a decreasingly reliable trans- mission network in many regions of the united states, with grid components be- ing operated close to (or at) their techni- cal limits. the energy policy act of includes provisions to respond to some infra- structural problems, such as incentives to increase investment in transmission lines and to simplify the planning and permitting process for building them. these measures may help, as thousands of miles of new transmission lines may be required if the electric-utility system expands along the same lines as it has for the past several decades. increasing demand for other forms of energy in the future may also stress the country’s infrastructure. numerous new port ter- minals will be required to handle in- creased imports of lique½ed natural gas and oil, for example. at the same time, new carbon-sequestration sites, bio- energy facilities, and hydrogen reposito- ries and pipelines may be needed, espe- dædalus summer comment by marilyn a. brown, benjamin k. sovacool & richard f. hirsh cially as efforts increase to reduce envi- ronmental pollution. but these needs will not be easily met. carbon seques- tration, for example, may require use of depleted oil and gas ½elds, unmine- able deep coal seams, or cavernous sa- line formations. the successful use of these geological formations will depend on techniques that resist operator and equipment failure, extreme weather, and malicious interference or attacks. similar concerns over technical errors and assaults arise when considering the need for expansion of natural-gas and petroleum facilities. opposition to con- struction of these new infrastructural elements has already become evident. put simply, the future health of the country’s energy infrastructure may be in peril. fourth, the country faces immense challenges in promoting more energy- ef½cient technologies. before the opec oil embargo, u.s. energy con- sumption grew in lockstep with the na- tion’s gross domestic product (gdp). measured in terms of energy consump- tion per dollar of gdp, the energy inten- sity of the nation remained constant. economic growth appeared to require consuming more energy. this trend changed in the period after the energy crisis, when the econo- my (as measured by the inflation-adjust- ed gdp) grew by percent (from to ). total u.s. energy consump- tion, meanwhile, grew from about sev- enty-six quadrillion british thermal units of energy (quads) to almost one hundred quads in the same period, an increase of percent. the energy in- tensity of the economy, in other words, dropped considerably. what accounted for the change? in- dividuals purchased more fuel-ef½cient cars and appliances; they insulated and weatherproofed their homes; and they adjusted thermostats to reduce energy consumption. these measures led to a decrease in per capita residential ener- gy use of percent (and percent per household) despite a percent increase in new home size since and the growing use of air conditioning, elec- tronic equipment, and a multitude of ‘plug loads.’ businesses retro½tted their buildings with more ef½cient heating and cooling equipment and installed en- ergy management and control systems, accounting for a percent decline in en- ergy use per square foot of commercial building space. factories adopted more ‘energy-stingy’ manufacturing processes and employed more ef½cient motors for conveyors, pumps, fans, and compres- sors. these gains in energy productivi- ty, prompted by high fuel costs and gov- ernment policies, represent one of the great economic success stories of this century. if the nation’s energy intensity remained the same today as it stood in , the united states would be con- suming twice as much energy, and its energy bill would be approximately $ billion higher per day. while such data suggest that energy- ef½ciency investments provide an eco- nomic and relatively rapid strategy for meeting the growing demand for ener- gy services, many experts assert that ef½ciency can only play a limited poli- cy role. for example, hans blix, the for- mer director of the international atomic energy agency, has argued, “the more ef½cient use of energy will only partially slow down the expanding use of energy. although our light bulbs will save elec- tricity, we shall have more lights.” simi- larly, vice president dick cheney stated in that “conservation may be a sign of personal virtue, but it is not a suf½- cient basis for a sound, comprehensive, energy policy.” and spencer abraham, president bush’s secretary of energy dædalus summer assessing u.s. energy policy from to , reiterated this view when he told senators that “improved energy ef½ciency cannot do the whole job . . . . [t]he united states will need more energy supply.” in short, ef½ciency may help the nation overcome some of its energy woes, but policymakers do not feel it will be the ultimate solution. as a result, the potential for improved energy ef½ciency is not being vigorously tapped. fifth and ½nally, the trend toward more energy consumption will exacer- bate already prominent concerns about the environment. since the s, tech- nically trained people, politicians, and the public have become aware of the health consequences of the exploration, extraction, transportation, and combus- tion of fuels used for making energy. they have also become alert to possible dangers of living near high-voltage pow- er lines and radioactive-waste sites. more recently, people have pointed to the ecological damage created by hydro- electric dams and wind turbines, while also noting that the use of biomass from energy crops may promote agricultural monocultures that can pose severe risks to ecological diversity. efforts resulting from three decades of clean-air legislation have decreased sulfur-dioxide emissions from electric generators in the united states. never- theless, air pollution remains a serious threat to human and ecosystem health. americans have experienced a rise in respiratory illnesses, and visibility con- tinues to degrade in formerly pristine areas as a result of pollution from ve- hicles and coal-burning power plants. rarely, for example, does visibility in the great smoky mountains national park achieve its ‘natural’ limit of nine- ty-three miles. instead, average annual visibility has decreased to twenty-½ve miles in the winter and to twelve miles in the summer. beyond air-pollution issues, current energy trends will lead to expanded emissions of greenhouse gases, which appear to be contributing to increased global temperatures, reces- sion of glaciers, and more frequent and powerful weather events such as hurri- canes. the pollution associated with elec- tric-power production was vividly doc- umented by the august , , north- east blackout. not only did the event shut off electricity for million people in the united states and canada, it also halted emissions from many fossil-½red power plants across the ohio valley and the northeast. in effect, the power out- age served as an inadvertent demonstra- tion of the environmental consequences of electricity generation: twenty-four hours after the blackout, new york city’s sulfur-dioxide concentrations dropped percent; particulate matter fell by percent; and ozone concentra- tions slipped to half. beyond federal clean-air initiatives, state-government policies have, in cer- tain cases, made positive inroads to pol- lution abatement. due to legislative and regulatory initiatives, california–which generates roughly one-fourth of its elec- tricity from ef½ciently distributed and renewable energy technologies–emitted only metric tons of carbon dioxide in , a mere percent increase from its emission levels in , despite an in- crease in electricity demand of almost percent. though making impressive inroads in pollution abatement efforts, california (and a few other states) remains the ex- ception, not the rule. few people dispute the fact that total u.s. emissions of car- bon dioxide from energy consumption have increased signi½cantly: from . billion metric tons in to . billion metric tons in . moreover, the ener- dædalus summer comment by marilyn a. brown, benjamin k. sovacool & richard f. hirsh gy information administration forecast- ed in that carbon-dioxide emis- sions from energy use will grow an aver- age . percent annually for the next twenty years, resulting in . billion met- ric tons of carbon-dioxide emissions in . clearly, the last thirty years have not seen the adoption of the low-carbon power and fuels needed to help stabilize atmospheric concentrations of green- house gases. continued growth in ener- gy usage will likely exacerbate environ- mental problems. to conclude, despite three decades of ‘progress’ since the energy crisis, the united states faces a host of energy challenges that threaten the nation’s economy, security, and lifestyle. because of its huge dependence on imported oil to fuel a transportation sector that has seen little improvement in energy ef½- ciency, the nation could be ravaged by disruptions to oil supplies due to weath- er, war, or terrorist attacks. at the same time, growing electricity consumption and reliance on power plants employing natural gas, along with a constrained transmission grid, make the electric- utility infrastructure increasingly vul- nerable to service disruptions. and while ef½ciency efforts have successful- ly stemmed the growth rate of fuel con- sumption in the last few decades, popu- lation increases and economic expan- sion have forced up the nation’s overall use of energy, exacerbating the country’s environmental problems. as a consequence of these trends, the goal of energy independence seems more distant in than it did in , when president nixon ½rst proposed it as a way to deal with the oil embargo. while one can fruitfully debate whether complete reliance on domestic energy sources should be the objective of gov- ernment policy, the fact remains that the united states cannot continue upon its present course. the country has become progressively vulnerable to economic, political, and military threats because of its growing fuel consumption and an increasingly challenged energy infra- structure. the nation’s policymakers in business and government, as well as the citizenry, need to realize that the recent trends in energy consumption, produc- tion, and distribution reflected in this energy assessment cannot be sustained inde½nitely. americans must confront energy concerns as a top priority and learn to overcome the social, political, and technical obstacles that have hin- dered true progress for more than three decades. dædalus summer assessing u.s. energy policy renewable energy deployment to combat energy crisis in pakistan review open access renewable energy deployment to combat energy crisis in pakistan abdul raheem , , sikandar ali abbasi , asif memon , saleem r. samo , y. h. taufiq-yap , michael k. danquah and razif harun * abstract the huge deficiency of electricity due to heavy reliance on imported fuels has become a significant impediment to socio-economic development in pakistan. this scenario creates an increase in local fuel prices and limits potentials in the establishment of new industrial zones. the current gap between the demand and production of electricity in pakistan is approximately – mw with a constant increase of – % per annum. hence, more sustainable and renewable energy sources are required to overcome the existing problem. pakistan is endowed with potential renewable energy resources such as wind, solar, hydro, and biomass. these resources have the capacity to be major contributors to future energy production matrix, climate change reduction efforts, and the sustainable energy development of the country. this article reviews the availability of alternative energy resources in pakistan and associated potentials for full-scale development of sustainable energy systems. it also discusses exploitation strategies to increase the distribution of indigenous energy resources. keywords: energy crisis, sustainability, renewables, biomass, pakistan review background pakistan is one of the most populated countries in the southern asia region, contributing approximately . % of the total global population. the country is expected to serve as an international trade and energy corridor in the near future due to its strategic location [ , ]. hence, among other social, economic, and political factors, pakistan needs to ensure its energy supplies meet the direct and indirect demands of the country not only for maintaining economic growth but also for supporting regional and global economic initiatives. the vast deficit between demand and supply of electricity recorded in – was . %. this figure has increased up to % during the summer of [ ]. a routine problem is that electricity supply cannot be maintained during peak hours, resulting in frequent power shutdown (load shedding) of – h in urban areas, and – h in rural areas. as a result, many entrepreneurs and industrialists have invested and moved their businesses to neighboring countries [ ]. hence, short- and long- term measures are required to solve the existing energy problems. the present state of pakistan’s energy resources is summarized (fig. ). it can be seen that indigenous energy sources mainly consist of oil ( %), hydro ( %), natural gas ( %), and coal ( %) [ ]. sustainable supply of energy to meet the current and future domestic and industrial demands in pakistan will rely on full-scale generation from the different energy sources in order to make significant contributions to the supply chain. current energy generation has a huge financial burden on the country’s economy due to the importation of oil to support existing mix, and the situation is heightened by the rapid declination of domes- tic gas assets. according to the board of investment pakistan, the installed power capacity is , mw. however, current generation stands between , and , mw per day, against peak a demand of , to , mw [ ]. figure shows the average annual demand of electricity, which is increasing at a constant rate of – % annually. * correspondence: mh_razif@upm.edu.my department of chemical and environmental engineering, universiti putra malaysia, serdang , malaysia full list of author information is available at the end of the article energy, sustainability and society © the author(s). open access this article is distributed under the terms of the creative commons attribution . international license (http://creativecommons.org/licenses/by/ . /), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the creative commons license, and indicate if changes were made. raheem et al. energy, sustainability and society ( ) : doi . /s - - -z http://crossmark.crossref.org/dialog/?doi= . /s - - -z&domain=pdf mailto:mh_razif@upm.edu.my http://creativecommons.org/licenses/by/ . / the acute shortfall and burden imposed by oil impor- tation creates a huge economic constraint for the country [ , ]. various efforts have been made by different governmental organizations and international bodies such as asian development bank (adb) and world bank to stabilize the energy situation. they share similar objectives to enhance fossil fuel production for electricity generation. unfortunately, governmental efforts to address concerns relating to energy security, climate change, and sustainable development have been minimal. whilst little effort is put into increasing domestic fossil fuel (gas, coal, and oil) based electricity, the search for alternative fuel sources which are more sustainable and renewable should be a major national priority. renewable energy in pakistan was reported to be < % in . however, pakistani govern- ment has targeted to achieve % of renewable energy by [ , ]. the article reports on the potential and exploration of renewable energy as a major contributor to future sustainable energy pursuits in pakistan. renewable energy potential in pakistan pakistan has four main renewable energy sources. these are wind, solar, hydro, and biomass. these resources have a significant potential to provide solutions to the long-lasting energy crisis in pakistan [ ]. hence, a steady development of these resources is a crucial step to over- come the existing energy challenges in an environmental friendly manner. among the different renewable energy sources, solar energy has received the most research attention [ – ]. sheikh [ ], for instance, evaluated the potential of solar photovoltaic (pv) power generation capacity with % efficient pv panels over area of km , which is . % of total land area of the country. from the results, it was concluded that cover- ing km area of land with pv panels can produce energy equivalent to million tons of oil equivalent (mtoe) in pakistan. gondal and sahir [ ], considered . % of urban regions for pv installations to estimate the total energy generation capacity based on solar pv system. a survey conducted by hasnain and gibbs [ ] showed that the interior part of the county consists of mainly agricultural land, which is appropriate for the development of biomass feedstock, whereas northern and southern corridors have a significant potential for hydro, wind, and solar. this finding is useful as it might possibly improve the diverse energy supply market and decrease the dependency on imported fuels and environ- mental pollution. figure shows the entire spectrum and end-uses of alternative sources which are the best options to meet basic requirements of energy needs, with various employment openings, local manufacturing. it has been projected that pakistan will contribute up to , mw to its energy mix through renewable energy resources by [ ]. therefore, timely and appropriate progress to exploit the potential of different natural energy resources will have a tremendously influ- ence in meeting future projections. wind energy the development and use of alternative energy resources have been a major endeavor since . the pakistani government has set up a recognized body [ ], to coor- dinate efforts in this area. this organization plays an important role in narrowing the gap between demand and supply of electricity by promoting the utilization of renew- able energy. pakistan’s meteorological department (pmd) has collaborated with the national renewable energy laboratories (nrel), usa, to conduct a wind speed sur- vey of different locations in sindh and baluchistan provinces with height ranging from – m. the data from the feasibility studies were analyzed by alternative fig. distribution of indigenous energy sources available in pakistan [ ] m w years supply demand fig. electricity demand and supply trends for pakistan from to [ , ] raheem et al. energy, sustainability and society ( ) : page of energy development board pakistan (aedb) [ , ], and it was found that a vast area of km with a high wind speed was discovered and zoned as “gharo-corridor” as shown in fig. . the area has a significant potential to produce around , mw of electricity. however, due to the occurrence of other economic activities, only % of the area can be utilized with a produc- tion potential of , mw [ , ]. moreover, significant wind speeds were identified in the costal part of baluchistan, particularly in swat and some fig. end-uses of renewable energy resources fig. wind mapping stations in sindh with a potential to produce , mw at a height of m [ ] raheem et al. energy, sustainability and society ( ) : page of of the northern areas. out of examined sites, seven have a capacity factor ranging from to % and are ap- propriate for bonus wind turbines (model / mk iv) [ ]. however, the potential of these sites is still being ex- plored although the capacity is not enough to contribute to the national grid. nrel, together with the united states agency for international development (usaid), has identified a total gross wind resource of , mw in pakistan, where approximately , mw can be technically exploited to power the national gird [ ]. re- cently, a wind project with mw capacities has been completed in [ ]. in addition, more than wind turbine companies are approaching aedb to install mw wind project [ ]. at the moment, the first phase of the zorlu wind project generating mw is in operation whilst a mw plant is yet to be installed. dif- ferent wind power projects with a cumulative capacity of approximately mw are at different phases of con- struction and would be completed in the near future. the pakistan council of renewable energy technologies (pcret) has installed nearly small wind turbines ranging between . and kw with a cumulative power output of kw at the different areas of sindh and baluchistan, powering homes including security check posts [ ]. also, thousands of small wind turbines with a capacity of – w have been installed by dif- ferent non-governmental organizations (ngos), electri- fying rural areas of sindh province. most recently, three villages of baluchistan have been powered using a wind/ pv hybrid system [ ]. with further investment and devel- opment, wind energy could become a major component of sustainable energy future in pakistan. solar energy solar is believed to be one of the most endowed renewable energy sources. it is reliable and capable of producing substantial amount of energy without po- sing adverse impacts on the environment. generally, pv cell and solar thermal conversion systems are used to capture sun energy for various applications in rural and urban areas. pv technology is capable of conver- ting direct sun radiation into electricity (fig. ). solar thermal technology uses thermal solar collectors to capture energy from the sun to heat up water to steam for electricity generation [ , ]. pakistan with a land area of , km is located between longitudes ° and ° east and latitudes ° and ° north [ ]. this unique geographical position and climate conditions is advantageous for the exploi- tation of solar energy. almost every part of the country receives – h day− high solar radiations with more than sunshine days in a year [ , ]. figure illus- trates the range of solar radiation levels per month in the major cities of pakistan. the prospects of solar energy in pakistan have also been widely investigated by many researchers [ – ]. adnan et al. [ ] analyzed the magnitude of solar radiation data for different pmd stations, and the data showed that over % of the total area of pakistan receives solar radiations of – kwh m− day− . ahmed et al. [ ] and ahmed et al. [ ] used different methods to estimate and characterize direct or diffused solar radiations in many parts of the country. khalil and zaidi [ ] conducted the survey of wind speed and intensity of solar radiations at different locations of country. fur- thermore, the data was then compared among wind tur- bine ( kva), solar pv ( kva), and gasoline generator ( kva) (table ). the comparison showed that the wind and solar energy are most appropriate alternative resources. the study also found that the kw of solar pv can produce . kw of electricity, which can signi- ficantly contribute to reduce load shedding in pakistan. hasanain and gibbs [ ] detailed out the significance of solar energy in rural areas of the country. aedb has estimated that pakistan has about , , mw ( gw) of solar power potential [ ]. the main obstacles to full-scale exploitation include ( ) high cost, ( ) lack of technology, ( ) socio-political be- haviors, and ( ) governmental policy conflicts. in , the chief minister of punjab launched the “ujaala” program, where w pv panels were dis- tributed among university students throughout the country. this program aimed at encouraging people to utilize alternative energy and cut-down their dependency fig. a schematic drawing of the mechanism of operation of solar photovoltaic systems raheem et al. energy, sustainability and society ( ) : page of on the national gird. another project introduced by the government was the “quaid-e-azam solar park.” this solar park is built to produce mw of electricity by [ ]. it is projected that the largest solar photovol- taic electricity production will be established after [ ]. pcret has set up approximately solar pv units of kw capacities to power homes, colleges and mosques, including street lighting [ ]. aedb has powered families by installing kw pv system together with w solar charged lighting systems [ ]. many ngos are effectively working to install pv units in several parts of the country. the solar street lamps and solar charging lights for households are particularly of major interest. pakistan has a target of electrifying approximately , villages via solar pv by [ ]. solar water heating the solar water heating technology has been extensively applied in pakistan with an annual growth rate of % during the last four years [ , ]. aedb has started a consumer confidence building program (ccbp) to pro- mote solar water heating system in pakistan. the main objective of this program is to create awareness and build-up consumer confidence thorough various incen- tives. at present, there are companies importing solar geysers, including local manufactures [ ]. the main factors contributing to growth pattern are heftiness, affordability, technological reliability and increasing scar- city of natural gas. it is estimated that approximately of solar water heating units will be operated in the country by , and projected to be , units by without any governmental subsidies [ ]. accor- ding to han et al. [ ], utilizing solar water heating tech- nology instead of natural gas or conventional sources has significant advantages on economic, environmental, and social sustainability. solar water desalination solar desalination is a new and cost-effective technology to remove salt and other minerals from water for daily life applications. the technology desalinates brackish water or seawater either using solar distillation or an indirect method whilst converting the solar energy into heat or electricity [ – ]. it is an environmentally advantageous and cost-effective technology; hence, it is much patronized by communities in rural regions [ ]. arjunan et al. [ ] described the design layout and func- tioning principles of an installed solar water desalination unit in awania, india. they reported that the distillation of brackish water using solar energy is an effective way to provide potable water for rural communities in arid and semi-arid zones. this makes it a potential techno- logy to be employed in different areas of pakistan where fresh water availability is limited such as thar deserts and cholistan regions. most of the regions in the coun- try have brackish subsoil water which is not appropriate for human and other living inhabitants [ ]; hence, desalination by means of solar energy will be beneficial and sustainable in providing portable water for the rural areas of sindh, baluchistan, and punjab [ ] fig. minimum and maximum range of solar radiations in pakistan [ ] table running cost evaluation for different energy sources [ ] price (usd) fuel cons: (usd/h) maint: cost (usd/h) life (years) co (g/l) no (g/l) solar panel ( kva) gas generator ( kva) . . . – . wind turbine ( kva) . . – raheem et al. energy, sustainability and society ( ) : page of the government of balochistan has installed two solar plants in gawadar, comprising stills and each plant has the capacity to treat up to g day− of sea water. projects to develop the same solar plant system have been initiated in different areas of balochistan and other province of pakistan [ ]. the pakistan institute of engi- neering and applied sciences (pieas) has fabricated a single basin solar still with an optimized efficiency of . %, being comparable to stills used globally. industrial solar water heating apart from domestic use, solar water heating system is also used in various commercial and industrial applica- tions including laundries, hotels, food preparation and storage, and general processing and manufacturing. in the textile industry for example, water heating for dye- ing, finishing, drying, and curing consumes approxi- mately % of the total energy [ ]. processing and manufacturing industries also require water heating for various operations such as sterilization, distillation, eva- poration, and polymerization. solar thermal technology is one of the most effective solutions to achieve the desired temperature and productivity for the aforemen- tioned applications [ ]. pakistan is the fourth largest producer of cotton in the world; hence, this technology will contribute significantly to meet the water heating requirements of the cotton industry sustainably. as a major contributor to the economy of pakistan, the textile industry is facing serious challenges in maintaining the global environmental standards. the industry is energy intensive; thus, high energy costs and persistent shor- tages in demand and supply impact negatively on the production and competitiveness of the industry. full- scale operation of industrial solar water heating systems would contribute significantly to resolved energy prob- lems faced by the industry. energy is a crucial commod- ity on the international market, and its production and competitiveness are the functioning indicators [ , ]. water heating is an energy-intensive process and con- ventionally relies on the use of fossil fuels energy. solar water heating technology can benefit textile industries in pakistan by providing an economical choice and a po- tential alternative to conventional fossil-based routes. mass implementation of solar water heating systems will also reduce the environmental impacts associated with fossil fuels significantly. muneer et al. [ ] reported a payback period of years for solar water heating systems incorporated into pakistan textiles industries. muneer et al. [ ] also examined the prospect of solar water heat- ing system on turkish textile industry and estimated a payback period of ~ years. in view of the existing enormous potential, solar en- ergy offers a promising and useful option for pakistan in various commercial applications. the government needs to consider this technology as an important source of energy and promote massive and rapid investments to meet the supply of power in rural regions such as balochistan, thar desert, and cholistan, where grid connectivity is not accessible. biomass biomass is typically derived from plants, animals, and agricultural wastes. it has been in used for various applications such as cooking, heat, fuel, and electricity in rural areas. broadly, biomass is classified into four major groups: (i) agricultural waste, (ii) municipal solid waste, (iii) animal residue, and (iv) forest residue [ ]. however, plants and animals are the main sources of biomass production. almost billion tons of biomass is pro- duced globally each year from these sources, which is capable of producing substantial amount of energy without releasing high concentrations of carbon dioxide (co ) and other greenhouse gasses compared to fossil fuels [ , ]. technically, they can be converted into different products either using thermochemical or biochemical methods. however, each of the conversion methods has its own pros and cons and process condi- tions such as characteristics of biomass feedstock and the desired end product [ ]. biomass could be appro- priate and effective for commercial exploitation to gene- rate electricity throughout world, due to its characteristics for high value fuel products [ ]. pakistan is an agricultural country where most of its population (around %) lives in remote areas [ , ]. hence, the availability of biomass is very extensive particularly from agriculture and livestock sources, including crop residues and waste from animals. these wastes amount to , tons day− of solid waste, , tons day− of agricultural residue, and approxi- mately million tons day− of manure [ , , ]. due to limited access to grid electricity and advanced tech- nologies in these remote areas, most people are powered using traditional practices to fulfill their energy needs [ , ]. the sugar cane production industries produces bagasse as residue and this can be used to produce electricity to power sugar mills. pakistan is the fifth largest country worldwide with sugarcane producing capacity of over , , million tons. aedb and nrel, usa, have estimated mw of power gene- ration from sugarcane bagasse [ , , ]. in the view of present energy scenario, the government has authorized sugar mill owners to sell their surplus power to the national grid station under the limits of mw [ ]. moreover, urban areas produce large quantities of muni- cipal waste which could possibly be digested to produce biogas, a renewable fuel further used to produce green electricity, heat, or as vehicle fuel and the digested sub- strate, commonly named digestate, and used as fertilizer raheem et al. energy, sustainability and society ( ) : page of in agriculture [ , , ]. figure is added to explain working principles of biogas plant and applications of the produced products from the process. biogas technology is highly advanced in china and india. more than million domestic plants and nearly small and medium units were installed in china by , with an estimated production of million m of clean burning fuel to meet % of its total gas energy needs [ ]. a domestic biogas plant was launched in tibet, china to explore the potential of cattle manure as feedstock, and this has been successfully implemented to improve the social and economic conditions of the region [ ]. efforts have been made to implement biogas technology in pakistan. the first biogas plant was constructed in to process farmyard manure (fym) in sindh [ ]. however, only in did the government of pakistan start putting efforts into the implementation of residential biogas technology as an alternative source of energy. plants with fixed dome, portable gas digesters, and small tanks/bags are the three most frequently used designs for biogas operating plants in pakistan [ ]. currently, pakistan has more than installed biogas plants to meet its domestic fuel needs. these plants are efficiently producing up to . million m of biogas annually together with million kg year− of bio-fertilizer [ , ]. the total estimated nationwide biogas potential is about – million m day− [ , ]. there are oppor- tunities to utilize biomass to produce biogas in the coun- try’s remote regions through community biogas plant networks. almost million animals exist in pakistan with an annual growth rate of % [ , ]. the number is capable of producing enough biomass to generate over million m day− of biogas, which is sufficient to meet the energy needs of more than million peoples in the rural areas, along with approximately million tons day − of bio-fertilizer [ , ]. the collaboration between the ministry of petroleum and natural resources and the directorate general of new and renewable resources (dgnrer) enabled the installation of more than biogas plants by to . the plants were intended to produce about to ft day− of biogas for lighting and cooking applications [ ]. the scheme was divided into three stages. in stage , around chinese fixed-doom type plants were installed by dgnrer for demonstration purposes on grant-basis. in stage , the budget expenses for sponsorship was shared between the recipients and government, and in stage , all the eco- nomic sponsorships were withdrawn by the government though free technical supports continued but not reliable. however, the scheme failed due to the following reasons: (i) withdrawal of financial sponsorship by the government, (ii) technology was expensive to invest in and maintain, (iii) less technical awareness/training offered to the locals, (iv) lack of incentives, (v) low patronage or participation by the peoples, and (vi) ineffective demonstration [ ]. pakistan council of appropriate technology (pcat) also collaborated with gdnrer to develop a renewable energy technology strategy under the ministry of science and fig. working principles of biogas plant and products application [ ] raheem et al. energy, sustainability and society ( ) : page of technology. in , pcat merged with the national institute of silicon technology to form pakistan council of renewable energy technologies (pcret). the council develops and disseminates biogas plants and other suitable options of renewable energy generation into communities in the remote areas [ ]. currently, appro- ximately biogas plants have been installed with % of the cost shared between the recipient and pcret [ ]. on top of that, three community based plants were installed in the remote parts of islamabad, supplying energy to about homes. sahir and qureshi [ ] sug- gested that by installing pilot size plants, the available biomass can be used to operate high level biogas plants based on crops and dungs in the remote regions and street wastes in the urban areas. a biogas plant of m capacity has recently been set up in the area of cattle colony, karachi [ ], and the trials and preliminary opera- tions of the project were sponsored by new zealand aid (nzaid). there are , cattle in the area, producing wastes as the feedstock for the biogas plant. the initial generation capacity is ∿ kw of power, and this will be increased to mw with tons day− of fertilizer. another biogas plant at shakarganj mill, with the capacity to produce up to . mw, is still under construction through the help of aedb [ ]. in addition, pcret aims to provide alternate renewable energy system in rural house- holds/villages by installing , medium-scale biogas plants at various locations in the country by , with total annual biogas generation capacity of m [ , ]. biogas productivity and quality is greatly influenced by the waste type, waste composition, and operational para- meters such as temperature, feeding rate, retention time, particle size, water/solid ratio, and c/n ratio [ ]. a temperature range between and °c is found to be optimal for high biogas production rate [ ]. feedstock available and batch loading are also important parameters for efficient biogas plant operation and help to maximize biogas yield. however, over or under loading of feedstock and water affects the overall efficiency of the process. it has been observed that carbon is consumed times fas- ter than nitrogen during anaerobic fermentation by micro- organisms. therefore, to meet this requirement, microbes require – : carbon to nitrogen ratio with most of the carbon degraded within the minimum retention time [ , ]. retention time refers to the digestion period for which the waste remains inside the digester. it is estimated to be average days to few weeks depending on the waste composition, process parameters location of plant and atmospheric conditions [ ]. the digestibility of waste is essential to promote its decomposition into simple organics and biogas products. the digestibility is usually enhanced by treatments using calcium hydroxide, am- monia, and sodium hydroxide. water and urea can also improve waste digestibility [ ]. bioethanol and biodiesel pakistan has a considerable potential to produce biofuels such as bioethanol and biodiesel. the establishment of these biofuels will help reduce the oil demands of the country of which % is sourced by importation. various initiatives have been commenced by the govern- ment to increase biofuel production. pakistan sugar mills association (psma) is the agency responsible to develop bioethanol production in the country. sugar millers offer incentives and materials such as fertilizers and pesticides to sugarcane growers to enhance crop production and maximize bioethanol production [ ]. in , only out of sugar mills in the country had the facilities to convert raw molasses [ ]. with the existing production rate of sugarcane, pakistan has the potential to produce more than , tons year− of ethanol. however, only about a third ( , tons) is produced currently [ ]. though several small projects have been carried out to evaluate the commercial applications of bioethanol, significant efforts to develop and promote bioethanol are still lacking due to ineffective government policies and lack of infrastructure for large-scale manu- facturing. also, a major portion of the limited bioethanol produced is traded in different forms such as alcohol and molasses. a significant potential to produce biodiesel also exists in pakistan through the use of castor bean, a self-grown crop found in different parts of the country. it is estimated to produce more than kg oil ha− , which is significantly higher than other biomass such as corn ( kg oil ha− ), soybean ( kg oil ha− ) and sunflower ( kg oil ha− ) [ ]. due to its high oil content, castor bean can be a promising alternative feedstock for biodiesel production. castor oil has the advantage of being soluble in alcohol under ambient temperature conditions, and this is beneficial to biodiesel production. it is an untapped resource in the country; thus, utilization for biodiesel production will not only contribute to meeting the energy demands of the country but also emerge as a value-adding process that can promote economic, social, and environmental sustainabil- ity of the country. hydropower in pakistan water is one of the most vital constituents that support all form of life on earth and offers various other services such as power generation [ ]. hydropower relates to the generation of power from dropping water [ ]. the kinetic energy present in water dropping from elevated levels can be transferred into mechanical power via hydropower turbine and then to electricity using an electric generator (fig. ). the output of electricity is directly proportional to the elevation of moving water (pressure) and flow rate [ ]. raheem et al. energy, sustainability and society ( ) : page of based on the flow of water, hydropower power plants are classified into small and large. large hydro power plants require large dams together with water flow control mechanism [ , ], whereas small hydro power plants (shpps) are used to extract energy from low volumes of water flow such as canals, rivers, and streams [ ]. shpps are run-of-river systems, and thus do not require any extensive structures such as dam to store water, leading to significantly low environmental impacts [ , ]. hence, shpps are considered ideal renewable energy generation. hydropower is one of the most esta- blished and reliable renewable energy, contributing approximately % to worldwide energy market [ ]. hydropower plays a leading role in the total energy mix of several countries in the world. norway accounts for more than % of its power generation from hydro- power and brazil is almost %. similarly, canada pro- duces % and austria produces % of hydropower to meet their energy needs [ ]. india incorporated domes- tic fluvial systems by integrating its main rivers to im- prove hydrological control and to increase their hydropower production to , mw in [ , ]. hydropower is also a major energy source in china, and it is projected to contribute , mw of the total energy by [ ]. the technology is ongoing in countries in asia, and countries such as india, iran, bhutan, japan, kyrgyzstan, tajikistan, turkey, vietnam, and pakistan [ , ]. hydropower is a major source of renewable energy in pakistan with a great potential for shpps especially in locations between the arabian sea and mountainous areas such as hindu kush, himalayas, and karakorum. these features offer enough potential energy to the falling water to develop a maximum pressure [ ]. moreover, major rivers such as sutlej, ravi, chenab, and jhelum, falling into indus river can be explored for power generation [ , ]. the power generation capacity of shpps for the above sites is mw [ ]. pakistan has , , , . m capacity to store % of its annual river flow whilst the rest of the water directly flows down to the arabian sea [ ]. therefore, additional water storage capacity (such as dams) will be obligatory for future sustainable irrigation and electric power generation. in pakistan, the total estimated hydropower generation is over , mw, but unfortunately, only %, amounting to around mw, has been tech- nically exploited so far. ninety percent of this comes from hydropower resources in the northern parts of pakistan [ , ]. figure shows current operational hydropower projects in pakistan also shows the respec- tive projects that will be completed by to bring the installed capacity to over mw. in addition, wapda have completed a feasibility study of run-of-river hydro projects with combined installed capacity of approximately , mw at various locations in the country. this includes bunji ( mw), tarbela fourth extension ( mw), kohala ( mw), lower palas valley ( mw), mahl ( mw), and lower spat gah ( mw) [ , ]. apart from these run-of-river projects, there is also a high potential for large-scale reservoir projects (dams) including diamer basha ( mw), dasu ( mw), munda ( mw), kurram-tangi ( mw), and kalabagh dam (kb) ( mw). apart from electricity generation purposes, dams are also used to control flood in pakistan. one of the dams used for that purpose is kala-bagh (kb). at the provincial level, there are some objections for its con- struction; however, the perception has changed when the dam was used to control flood and saved lives during ’s flood [ ]. on that incident, over people were killed; $ . billion loss of economy and more than million people were highly affected in terms of their lives, homes, and crops [ , ]. sindh and khyber pakhtunkhwa provinces were the worst affected, those suffered immense losses [ ]. this massive destruction resulted long-lasting impacts not only on social human life and economy but it has also resulted in destruc- tion of natural environment posing land erosion, kill- ing of wildlife and other natural resources [ ]. the feasibility study of the kb dam showed the con- struction of a -ft high rock-fill dam that would be able to store approximately , , , . m of water [ ]. the dam consists of two spillways for effective distribution of flood water for instant and appropriate water disposal. during probable floods, these spillways are able to discharge more than million cusecs of water [ ]. the mean annual river flow at kb is high, approximately , , , . m due to the add- itional nullahs and other tributaries that join the indus river between kb dam and diamer bhasha dam. so, the approximate volume of flood to be managed at kb dam fig. design and operating mechanism of a hydropower plant [ ] raheem et al. energy, sustainability and society ( ) : page of is around , , cusecs [ ]. therefore, the develop- ment of kb dam is important to the government for flood management which capable in preventing future flood risks and combat energy crisis. to realize the full benefits of hydropower generation systems in pakistan, crucial policy reforms are obligatory to develop hydro- power by enhancing sustainable generation capacity. conclusions energy is crucial to the socio-economic development of all countries. a steady transformation is being observed throughout world from primary energy supplies based on conventional sources to renewable resources. pakistan continues to formulate efforts towards renewable energy endeavors. however, with the current gap between the demand and production of power in pakistan, which is approximately – mw with a constant increase of – % per annum, and the heavy dependence on limited fossil fuel resources, renewable alternatives which are able to commercially support conventional energy options must soon be in full-scale operation. wind, solar, hydro, and biomass are the resources that are abundantly present in pakistan. in table , the energy generation capacities of these resources stand at , mw for wind, , , mw for solar, mw for biomass, and , mw for hydropower [ , , , ]. this creates a fig. the major hydropower (hp) projects in service with installed capacity and under construction with proposed capacity in pakistan [ , ] raheem et al. energy, sustainability and society ( ) : page of significant potential to overcome existing fuel needs in the country. this potential capacity is fairly distributed among the different provinces. sindh is endowed with wind potential in the south, baluchistan is rich with solar potential in the west, and khyber pakhtunkhwa is rich with hydro in the northeast area. therefore, existing potential of renewables can be explored in four distant regions for power generation, water/space heating, engine fuel, and stand-alone power systems (saps). though different efforts have been made to address the roadblocks which renewable energy technologies (rets) face, the development has not been completely viable due to social, technological, economical, and informational hindrances. these concerns are the prime deterrents in the develop- ment of renewables. the country’s future energy should come from a balanced mixture of all these resources to steadily decrease its reliance on imported oil. the impor- tance should be given to more rapid and targeted ad- vancement of hydropower as large potential exists in country and most of feasibility studies have been con- cluded [ , ]. the supply of electricity from wind to grid has already started in . however, it is still a challenge due to some impediments such as absence of infras- tructure (e.g., large cranes, road network) and inadequate grid integration ability. therefore, it is necessary to address these challenges by prioritizing the provision of these facilities. the economical and user friendly solar cookers, solar water heaters, and solar dryers should be progressed, as instantaneous integration approach can have insightful influence on the overall energy demand in pakistan. the frequent public demonstrations and official campaigns must be carried out to educate the general public regarding environmental and commercial benefits of green energy, which will boost up the acceptability of those facilities. besides, the specific feasibility studies should be conducted for the installation of large-scale gird connected to solar thermal power stations. the renewable energy syllabus must be introduced from the primary to the university levels in the institutions to develop consen- sus in support of accepting renewables as energy sources in pakistan. the graduate students should be sent to foreign institutions to acquire more knowledge on emer- ging renewable energy technologies. policies for buying small scale renewable energy systems using a payable loan scheme for public should be framed. security, law, and order situations in country must be addressed at priority basis to encourage the attention of the local and foreign investors to invest in renewable energy. the power demand of pakistan is projected to increase up to , mw by the year [ ]. therefore, a more holistic approach by table summary of all renewable energy resources and their current status status completion date capacity (mw) reference wind technically exploitable potential , [ ] installed projects [ ] commissioned projects . [ ] projects under construction [ ] projects under feasibility study not known [ ] solar technically exploitable potential , , [ ] quaid-e-azam solar park (commissioned) [ ] projects under development [ ] projects under development [ ] projects under development . [ ] biomass technically exploitable potential in [ ] sugar mills ltd (unit-ii) at rahim yar khan (operational) . [ ] sugar mills ltd (unit-iii) at ghotiki (operational) . [ ] projects under development (at different locations in country) not known [ ] hydropower technically exploitable potential , [ , ] current production [ ] projects under development [ ] projects under feasibility study not known [ ] raheem et al. energy, sustainability and society ( ) : page of addressing all above mentioned issues are important to fully utilize the renewable energy potential to achieve a sus- tainable energy future of the country. a determined polit- ical will is the key to energy independence. competing interests the authors declare that they have no competing interests. authors’ contributions ar, srs, am, and yht-y developed the methodology and analyzed and interpreted the data collected. mkd, saa, and rh studied the conception and design and contributed to the critical revision and inputs into the manuscript. all authors read and approved the final manuscript. acknowledgements this work has been supported by the department of chemical and environmental engineering, universiti putra malaysia, malaysia. author details department of chemical and environmental engineering, universiti putra malaysia, serdang , malaysia. department of energy and environment engineering, dawood university of engineering and technology, karachi , pakistan. department of energy and environment engineering, quaid-e-awam university of engineering, science and technology, sindh , pakistan. catalysis science and technology research centre, faculty of science, universiti putra malaysia, serdang , malaysia. department of chemical and petroleum engineering, curtin university of technology, sarawak , malaysia. received: september accepted: june references . farooqui sz ( ) prospects of renewables penetration in the energy mix of pakistan. renew sust energy rev : – . sahir mh, qureshi ah ( ) assessment of new and renewable energy resources potential and identification of barriers to their significant utilization in pakistan. renew sust energy rev : – . sakran h, butt tt, hassan m, hameed s, amin i ( ) implementation of load shedding apparatus for energy management in pakistan. commun comput info sci : – . board of investment pakistan (boi) ( ) power and energy. available online at http://boi.gov.pk/sector/sectordetail.aspx?sid= . tajwar mi ( ) a report of hydro potential in pakistan. available online at http://www.wapda.gov.pk/pdf/brohydpwrpotialapril .pdf. pp - . . aziz mf, abdulaziz n ( ) prospects and challenges of renewable energy in pakistan. in energy conference and exhibition (energycon), ieee international (pp. - ). ieee . khan ha, pervaiz s ( ) technological review on solar pv in pakistan: scope, practices and recommendations for optimized system design. renew sust energy rev : – . shahbaz m, zeshan m, afza t ( ) is energy consumption effective to spur economic growth in pakistan? new evidence from bounds test to level relationships and granger causality tests. economic modeling : – . ullah i, chaudhry q-u-z, chipperfield aj ( ) an evaluation of wind energy potential at kati bandar pakistan. renew sust energy rev : – . raja i, dougar mg, abro rs ( ) solar energy applications in pakistan. renew energy : – . mirza uk, maroto-valer mm, ahmed n ( ) status and outlook of solar energy use in pakistan. renew sust energy rev : – . pakistan meteorological department (pmd) ( ) feasibility report of the establishment of commercial wind power plant of mw at gharo, pakistan. . sheikh ma ( ) renewable energy resource potential in pakistan. renew sust energy rev : – . asif m ( ) sustainable energy options for pakistan. renew sust energy rev : – . gondal ia, sahir m ( ) the potential of renewable hydrogen production in pakistan. sci technol vision : – . hasnain sm, gibbs bm ( ) prospects for harnessing renewable energy sources in pakistan. solar and wind technology ( ): . jatoi la ( ) policy for development of renewable energy for power generation: government of pakistan. pp. - . available online at http://www.aedb.org/documents/policy/repolicy.pdf. . alauddin a ( ) mw will be added to national grid soon: alternative energy development board (aedb) pakistan. 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assessment of flood impact on the environment in selected affected areas of pakistan. pakistan wetlands programme and undp pakistan. p available online at http://www.pakistanwetlands.org/reports/ reia% of% floods% in% selected% areas% -% final.pdf . luna ba, jabbar m ( ) kalabagh—a superior dam designers’ view point. in: st annual session proceedings. engineering congress, pakistan, p - . . alternative energy development board (aedb) pakistan. [http://www.aedb. org/index.php]. submit your manuscript to a journal and benefi t from: convenient online submission rigorous peer review immediate publication on acceptance open access: articles freely available online high visibility within the fi eld retaining the copyright to your article submit your next manuscript at springeropen.com raheem et al. energy, sustainability and society ( ) : page of http://pecongress.org.pk/images/upload/books/ .pdf http://pecongress.org.pk/images/upload/books/ .pdf http://www.bioenergyconsult.com/biomass-pakistan/ http://www.dawn.com/ http://pcret.netau.net/about% us.html http://www.itc.nl/flooding-and-pakistan http://web.worldbank.org/wbsite/ http://www.pakistanwetlands.org/reports/reia% of% floods% in% selected% areas% -% final.pdf http://www.pakistanwetlands.org/reports/reia% of% floods% in% selected% areas% -% final.pdf http://www.aedb.org/index.php http://www.aedb.org/index.php 	abstract 	review 	background 	renewable energy potential in pakistan 	wind energy 	solar energy 	solar water heating 	solar water desalination 	industrial solar water heating 	biomass 	bioethanol and biodiesel 	hydropower in pakistan 	conclusions 	competing interests 	authors’ contributions 	acknowledgements 	author details 	references working paper series working paper # developing an “energy sustainability index” to evaluate american energy policy marilyn a. brown and benjamin k. sovacool school of public policy georgia institute of technology december abstract: this paper proposes the creation of an energy sustainability index (esi) to inform policymakers, investors, and analysts about the status of energy conditions, and to help educate the public about energy issues. the proposed esi builds on the substantial body of literature on “sustainability” and also draws on past efforts to measure environmental and energy progress – both of which are reviewed below. the index covers four dimensions (oil security, electricity reliability, energy efficiency, and environmental quality) and includes twelve individual indicators. comparing these indicators in with , nine have trended in an unfavorable direction, two have moved in a favorable direction, and one has been essentially unchanged. clearly, the “energy problem” fretted about in the s has not been fully addressed. while the proposed esi is preliminary and requires further refinement, it takes an important step toward creating a set of indicators that can easily assess and communicate the condition of the u.s. energy system brown, marilyn a. and benjamin k. sovacool, . “developing an ‘energy sustainability index’ to evaluate energy policy,” interdisciplinary science review, ( ): - . doi . / x © institute of materials, minerals and mining. published by maney on behalf of the institute interdisciplinary science reviews, , vol. , no. developing an ‘energy sustainability index’ to evaluate energy policy marilyn a. brown* and benjamin k. sovacool† * school of public policy, georgia institute of technology, atlanta, ga - , usa † government and international affairs, virginia polytechnic institute & state university, blacksburg, va , usa how well are industrialised nations doing in terms of energy policy? without a stand- ardised set of metrics to evaluate national energy systems, it is difficult to determine the extent to which energy resources, technologies and infrastructure are truly keeping up with emerging challenges related to climate change, the environment, population growth and economic wellbeing. in response, we propose the creation of an energy sustainability index (esi) to inform policymakers, investors and analysts about the status of energy conditions. using the united states as an example, the esi shows that the country has failed to truly progress on solving some of its most pressing energy problems, and that in many respects conditions have deteriorated. the proposed esi builds on the substantial body of literature on ‘sustainability’, and draws on past efforts to measure progress in environmental and energy systems. to hear it from politicians and government spokespeople, one could easily be persuaded that the quality of the environment in the united states – as well as the health of the nation’s energy sector – has improved significantly since the energy crisis of the s. jeffrey r. holmstead of the us environmental protection agency recently suggested that the country ‘made the connection between polluted air and public health decades ago, and has worked steadily to reduce harmful emissions . . . as science has revealed more about the risks of various pollutants, efforts to monitor, control, and even eliminate these substances have grown ever more ambitious’. paula dobriansky from the us department of state put it even more succinctly: ‘the us record of achievement in addressing environmental issues over the past years is impressive’. we hear almost the same commentary coming from utility executives and self- proclaimed ‘conservative’ energy policy analysts. michael lynch, a former executive at chevron, recently argued that the tight oil market, warm weather, rising natural gas prices, and the ‘great majority’ of other factors are ‘obviously transient in nature, and do not require any major policy revisions’. paul l. joscow argues in his assessment of american energy markets that ‘considerable progress has been made and many useful lessons have been learned’. and bjorn lomborg suggests ‘the evidence clearly shows that we are not headed for a major energy crisis’. indeed, numerous other experts around the world have been quick to dispel claims of impending domestic and international energy crises as fabricated, exaggerated and untrue. analysts have explained away energy price spikes as simply marketplace manipulation, as in the californian electricity crisis of and the record-breaking gasoline prices of interdisciplinary science reviews, , vol. , no. marilyn a. brown and benjamin k. sovacool – . others have characterised talk about an energy crisis as a ruse to advance pro-industry policies and a way of relieving pressure on environmental issues. still other technology champions belittle ‘hype’ about energy problems by emphasising the ability of science to produce solutions, and energy resource analysts calm fears by pointing to abundant unconventional fossil resources such as tar sands, oil shale and methane hydrates. the evidence seemingly points both ways. on the one hand, the world energy crisis of / culminated in the establishment of the international energy agency, the creation of strategic petroleum reserves among its members, and the diversification of the fuel base for electricity as most countries moved away from their use of oil to produce electricity. in the us, the crisis forced sweeping energy legislation through congress, resulted in the establishment of the us department of energy, and even provoked president jimmy carter to cite the energy challenge as ‘the moral equivalent of war’ on april . since those times, the international community has seen advances in low-income energy services, efficiency and demand reduction programmes, renewable resources initiatives, and market restructuring of the various energy industries. in the us, many individual states have implemented aggressive renewable portfolio standards and systems benefits funds, started emissions trading schemes, and invested heavily in alternative fuels such as hydrogen, ethanol and biodiesel. on the other hand, a great disparity exists in the degree to which different countries have improved their energy sectors. as of january , eighteen members of the european union had set some type of national, mandatory target for promoting renewable energy, and on climate policy the eu greenhouse gas emission trading scheme (euets) calls for mandatory reductions in greenhouse gas emissions and allows countries to trade carbon credits. in the past five years even brazil, china, indonesia, nicaragua, sri lanka and turkey have adopted mandatory renewable energy or climate change targets. meanwhile, in the us, the federal government has failed to set a national target for renewable energy among regulated utilities, rejected a national cap on green- house gas emissions, and refused to create a nationwide trading system for carbon credits. as a result, there is growing evidence that the country’s lakes, rivers, streams, air and land continue to face rising levels of pollution, and the country’s power grid remains centralised, vulnerable and carbon dioxide-intensive. amidst the cacophony of rhetoric, posturing and lobbying, we seek to ask a simple question with a somewhat more complicated answer: how well are industrialised countries really doing in terms of energy policy? without a standardised set of metrics to evaluate the state of national energy systems, it is difficult to determine the extent to which energy resources, technologies and infrastructure are truly keeping pace with the growing demands of an expanding world economy. though considerable effort in the us has been dedicated, for example, to the development of composite indicators of transportation productivity, environmental quality and educational effectiveness, there are no standard composite metrics to evaluate the condition of the us energy system. thus, the enduring question – are our energy systems progressing or regressing? – remains difficult to answer. in response, we propose the creation of an energy sustainability index (esi) to inform policymakers, investors and analysts about the state of energy conditions. using the united states as an example, the esi shows that the country has failed to make real progress on solving some of its most pressing energy problems, and that in many cases conditions interdisciplinary science reviews, , vol. , no. developing an ‘energy sustainability index’ to evaluate energy policy have deteriorated. the proposed esi builds on the substantial body of literature on ‘sustainability’, and draws on past efforts to measure environmental and energy progress, both of which are reviewed below. while policymakers might use our esi to assess the relative vitality of any country’s energy system, why have we decided to focus on the us? by any standard, the united states is the largest consumer of energy. in , it consumed twenty-three per cent of the world’s total primary energy production, and its per capita consumption of energy is also one of the highest in the world. the country constitutes the world’s largest market for power equipment. it has more automobiles, nuclear reactors, pipelines, refineries, power producers and electricity customers than any other state. in , for example, the us possessed twenty-five per cent of the world’s installed electricity capacity. since the us remains the world leader in the extraction, consumption and use of oil, uranium, coal and natural gas, its decisions affect the global energy marketplace. the size of its energy system suggests that trends occurring in the united states may occur elsewhere, and that knowledge of its energy policy problems may help policymakers all over the world better understand how to promote more sustainable forms of energy use. of indexes and indicators a variety of experts have long used quantitative data to measure all types of conditions. in particular, much progress has been made in developing better tools for environmental impact assessments and cost-benefit analyses. over the past three decades, quantities such as levels of food production, trends in plant growth, and the movement of nitrogen across the us have been carefully tracked, monitored and recorded. the us environmental protection agency’s report on the environment, for instance, will have chapters addressing outdoor and indoor air quality, water, land, human health and the condition of ecosystems. moreover, practitioners in the field of environmental impact assessment seem to have abandoned their classical approach of narrowly analysing the ‘environmental impacts’ of technologies, in favour of a more holistic methodology assessing the ways technologies influence a panoply of social, economic, cultural and ecological forces. what would once have been an examination of, say, the effects of a large dam on local salmon populations would now investigate that dam’s influence on property rights, the expansion of local agriculture, community employment, tax structure, disturbance of view-scape, educational potential and a whole host of other ‘sustainability concerns’. such efforts often result in immense checklists full of data, ranging from the ecological integrity of wetlands to catalogues of endangered species in the arctic. in other aspects of our daily lives, cholesterol and blood pressure reflect the extent of our physical health; the dow jones index, unemployment rate, inflation and gdp indicate the comparative health of the economy; literacy, infant mortality, crime and life expectancy rates are used to measure the inherent progress of a given society; the united nations uses its human development index to rank entire countries based on sophisticated economic, health and educational attainment measures. in his introduction to the principles of morals and legislation, radical philosopher jeremy bentham ( – ) even created numerical indicators to quantify happiness – hedons – that he believed could be used to assist people trying to calculate whether their decisions would bring them pleasure. interdisciplinary science reviews, , vol. , no. marilyn a. brown and benjamin k. sovacool this is not to say that such quantitative measures are perfect, or that reducing complex situations to numbers is without problems. numerical indices often measure not what is most significant or meaningful, but merely what is measurable. quantitative measure- ments, especially those taken out of context, can also conceal important nuances and varia- bility. does a reduction in pedestrian casualties mean that roads are getting safer, or that they have merely become so dangerous that no one dares to cross the streets? or does a reduction in the energy intensity of a given country mean that its economy is becoming more energy efficient, or that instead more energy-intense products are being imported from elsewhere? as kevin d. haggerty put it, ‘numbers are like people; torture them enough and they’ll tell you anything’. yet while they have their flaws, such indicators – with perhaps the exception of bentham’s – help condense voluminous data into usable form. they can be useful for shaping public attitudes regarding air or water quality or the extent of biodiversity loss. indicators provide a necessary baseline for measuring progress, and can illustrate the com- plexity and interconnectedness of pressing problems. they make it easier for scientists to understand and devise research strategies, and can help focus on important interactions between different issues and data measurements. however, despite the obvious utility of numerical indicators, none has been proposed that measures the sustainability of a country’s energy decisions. we find this puzzling, as energy is one of the ubiquitous components of our modern lifestyles. it powers our vehicles, lights our workplaces, is essential for producing food, enables the manufacture and distribution of products, cools and warms our homes. energy is, according to economist e. f. schumacher, ‘not just another commodity, but the precondition of all commodities, a basic factor equal with air, water, and earth’. thus, energy is something used, directly and indirectly, by every living person. four historical modes of energy policy analysis this is not to say that there has not been much talk – both recently and historically – about energy in modern society. our brief assessment of energy policy distinguishes at least four distinct modes of energy analysis to date. from the s to the early s, energy dis- cussions were primarily dominated by economists emphasising the importance of energy to economic performance. studies frequently measured economic performance and growth – using indicators such as gnp (gross national product) – and compared these to the amount of energy a given country consumed. these assessments found strong parallelism between energy use and economic growth, and perpetuated the uncontested idea that increases in energy consumption were essential to the continued growth of industrialised economies. energy policy analysis, then, consisted of calibrating economic performance against energy consumption, and of devising strategies to ensure adequate supply to guarantee economic expansion. a more refined type of energy analysis emerged with the energy crises of the s, challenging the assumption that energy consumption and economic wellbeing were destined to grow in a lock-step relationship. new studies suggested that advanced societies differed greatly in their per capita energy consumption. longitudinal studies of energy use patterns and cross-national surveys comparing countries with similar standards of living all seemed to point in the same direction: a threshold level of high energy consumption had interdisciplinary science reviews, , vol. , no. developing an ‘energy sustainability index’ to evaluate energy policy to be met for a society to achieve industrialisation, but after that threshold had been crossed a wide latitude in the amount of energy needed to sustain standards of living existed. energy analysis became a means of finding out how much efficiency could be achieved and of exploring alternatives for those countries that had already crossed the consumption threshold. a third type of analysis started to take hold near the end of the s and continues to the present. such studies are predominately concerned with producing forecasts of the future and characterising scenarios of alternative futures. reports from the us energy information administration (eia), environmental protection agency (epa) and interna- tional energy agency (iea) typically focus on estimating generation capacities, projecting fuel costs and predicting the environmental impacts of particular energy technologies. for example, the paragon of excellence among these types of reports, the eia’s ‘annual energy outlook’, predicts the current and future technical potential for energy technologies, but does not anticipate expected policy changes or provide policy recommendations. this type of analysis focuses on different technological options, and provides insight into how supply and demand should be managed. analysis frequently extrapolates current trends, creates a picture of a future world, and informs policymakers of the different options for accomplishing such a vision. a fourth type of analysis concerns technology assessment, or focuses on how to diffuse a particular technology into the marketplace. the edison electric institute (eei) and electric power research institute (epri) tend to centre purely on the economics of electricity supply and demand, while reports from groups like the pew center on global climate change and the natural resources defense council emphasise the environmental dimensions of energy consumption. the us national academies of science and union of concerned scientists have produced insightful analysis of the security and infrastructure challenges facing the energy sector, while groups like the alliance to save energy and the american council for an energy efficient economy remain principally concerned with conservation and energy efficiency. other groups – including the nuclear energy institute, american wind energy association, the american solar energy society, and the combined heat and power association – focus on particular types of technologies. energy analysis, in this light, involves picking optimal technologies and then attempting to integrate them into society. the treatment of sustainability in modern energy policy while the bulk of energy policy analyses have thus avoided talking about sustainability in a coherent or comprehensive fashion, the idea has slowly begun to take hold – albeit in more of an ad hoc fashion. in its classic sense, the concept of sustainability encompasses the notion of balancing current resource consumption with the resource requirements of future generations. for example, the landmark brundtland report of the world commission on environment and development (published under the title our common future) defined sustainable development as meeting ‘the needs of the present without compromising the ability of future generations to meet their own needs’. historically, sustainability has meant balancing two sets of equally tenuous concerns: the present with the future, and energy consumption and economic growth with ecological integrity. interdisciplinary science reviews, , vol. , no. marilyn a. brown and benjamin k. sovacool sustainability is frequently theorised as having two forms: ‘weak’ and ‘strong’. the notion of ‘weak’ sustainability – predicated on neoclassical economic theory – assumes that manufactured and natural capital are close substitutes, so that environmental damage can be measured in monetary units. an optimal strategy for attaining sustainability, then, centres on finding the best way to allocate such resources. pearce and atkinson, for instance, argue that damage to the environment can be calculated economically through concepts such as capital, interest, savings and depreciation. similarly, hueting and bosch suggest that water, soil, forest, air and other natural resources should be assigned monetary value so that society can better assess what would be needed to reach a sustainable level of consumption. the idea of ‘strong’ sustainability recognises that environmental problems expand beyond mere questions of allocation to include notions of distribution and scale. resour- ces should be distributed justly, and their distribution and consumption must achieve a state where economic activity does not compromise global ecological carrying capacity. strong sustainability attempts to incorporate scale, equity and efficiency into the weak model. the most important task of economic policy, following the logic of the strong model, is to ensure that the economic system does not grow to a size that endangers the global ecological system. popular measurements and indices for ‘strong’ sustainability include the notions of eco-capacity (ensuring that economic growth and development do not compromise the integrity of ecosystems), eco-intensity (measuring the material intensity or eco-efficiency of products), and eco-space (measuring the spatial and land impacts of a given technology). in practice, when applied to energy policy, sustainability has meant pursuing one of three management rules: ensuring that the harvest rates of natural resources do not exceed regeneration rates; making sure that waste emissions do not exceed relevant assimilative capacities of ecosystems; and guaranteeing that non-renewable resources are only depleted at a rate equal to the creation of renewable ones. thus, any index of energy sustainability must reflect the resources consumed to meet current energy demands while also including the ability of future generations to meet their requirements. this can be measured as the total energy consumed by a given country in a given year (e.g. approximately thirty trillion kilowatt-hours for the united states). alternatively, it can be quantified in terms of total energy consumption per capita or energy use per gdp, which are measures of energy intensity or energy productivity. these measures are often emphasised because they recognise the correlation between energy use and level of economic activity. many similarly discrete indicators reflect the ability of future generations to meet their needs, such as measures of reliance on renewable energy v. fossil fuels, consumption of domestic v. imported fuels, as well as price trends and levels of investment in new energy infrastructure. ideally, these indicators should be reduced to a single metric, so that all dimensions of the question can be reflected in a single index value. this is done, for instance, in the notion of ecological footprint, an index that converts, for comparative purposes, all energy, materials and other resources associated with different built envi- ronments into equivalent land area requirements. the appeal of this metric is its ability to take account more fully of the resource implications of different policies and outcomes such as different built environments. ecological footprint studies by wackernagel and rees, walker and rees, merkel, and others are especially useful because they assess energy consumption at the micro-level, often at the scale of the community or household. for interdisciplinary science reviews, , vol. , no. developing an ‘energy sustainability index’ to evaluate energy policy instance, walker and rees note that almost half a given canadian household’s impact on the environment has more to do with associated travel requirements than with the home itself. other aggregate indicators with energy dimensions have been developed, notably the leadership in energy and environmental design (leed) index developed by the us green buildings council to help commercial building developers evaluate a variety of green building designs in the early stages of development. under leed, building projects are awarded points in six categories: sustainable sites, water efficiency, energy and atmosphere, incorporation of local and recycled materials and resources, indoor environmental quality, and innovation and design process. while each of the historical modes of energy analysis can be very useful – measuring the consumption of energy within and between countries provides a key baseline for future comparisons; forecasts offer a dynamic tool for projecting the consequences of a society’s energy choices; assessments of individual technologies help track their diffusion into society – none provides a holistic account of energy sustainability. early calculations of energy consumption were typically ethnocentric and distinguished between industrialised and underdeveloped nations. energy forecasts often take for granted the existing con- figuration of the industry and thus restrict their consideration to a very narrow range of alternatives. technology assessment frequently narrows energy analysis, meaning that integrative concepts that combine systems and cut across technologies, disciplines and sectors of the economy are difficult to pursue. moreover, in their current incarnations, the concepts of sustainability, ecological footprint and leed ignore some dimensions – such as fuel diversity, energy prices and infrastructure investments – of the energy system. furthermore, such concepts vary greatly and often lack integrated and consistent meanings. the term sustainability, for instance, can simultaneously mean finding sustainable use of natural resources or sustainable distri- bution of natural resources; maximising the quality of life for present or future generations; protecting the biosphere or safeguarding humanity. proposing an energy sustainability index (esi) rather than merely assessing energy intensity, forecasting the future, assessing an indi- vidual technology, or promoting some abstract idea of sustainability, we propose to look more critically and comprehensively at energy sustainability. we have developed an energy sustainability index (esi) covering four dimensions of the us energy system: oil security, electricity reliability, energy efficiency and environmental quality. it is based on twelve indicators corresponding to these four dimensions as shown in the figure below: oil imports, petroleum prices, availability of non-petroleum fuels, fuel economy of vehicles, energy intensity, energy use per capita, natural gas imports, natural gas prices, retail electricity prices, annual investment in transmission and distribution, sulphur dioxide emissions, and carbon dioxide emissions. metrics such as ‘oil imports’ and ‘natural gas imports’ help measure the availability of some key natural resources; metrics such as ‘petroleum prices’ and ‘natural gas prices’ assess their economic cost and equity for lower income households; metrics such as ‘energy intensity’ and ‘energy use per capita’ reflect levels of consumption; and metrics such as ‘sulphur dioxide emissions’ and ‘carbon dioxide emissions’ take into account the state of the natural environment and a level of futurity. interdisciplinary science reviews, , vol. , no. marilyn a. brown and benjamin k. sovacool the four indicators of oil security suggest worsening or at best stagnant conditions. the rapid growth of us oil consumption, combined with shrinking domestic oil production, has resulted in increased dependence on imported oil, which now accounts for sixty per cent of total us oil consumption – up from twenty-two per cent in . recent trends in world oil markets, including the emergence of china and india as major contributors to global demand, continuing instability in the middle east, and refinery outages from gulf coast hurricanes have caused the price of oil to rise from its historic average of us$ per barrel in to $ per barrel in and more than $ per barrel during much of and . fuel diversity is an important long-term strategy for coping with oil dependence, price volatility and the dwindling supply of oil, but it has not improved: non-petroleum fuels (mostly natural gas, corn ethanol and electricity) actually represent a smaller fraction of the energy consumed by the us transportation sector in (at . per cent) than in (when it was . per cent). cellulosic ethanol shows great promise because it is made from fibrous or woody plant material, rather than from corn and other starches that are both energy-intensive to produce and important sources of food. similarly, diesel from biomass and wastes could displace a large fraction of us oil consumption without constraining food production. such fuels, however, are still primarily used only in niche markets. problems associated with the dominance of petroleum-based transportation fuels in the united states are exacerbated by the fact that the fuel economy of cars has been essentially unchanged for more than two decades. corporate average fuel economy (cafe) standards for cars peaked in at . miles per gallon. improvements in front-wheel an energy sustainability index for the us energy system: financial metrics are for and in us dollars unless otherwise indicated; the metrics shown in italics represent favourable or neutral trends, all other metrics suggest deteriorating conditions interdisciplinary science reviews, , vol. , no. developing an ‘energy sustainability index’ to evaluate energy policy drive transmissions, electronic fuel injection, enhanced power-train configurations and computer-controlled engines have been negated by consumer preferences for larger and more powerful vehicles. in addition, a greater number of cars populate the roads, and they are driven further each year. the consequence of these trends has been growing demand for oil in the transportation sector and greater imports to meet that demand. electricity reliability is also threatened. volatility in natural gas markets, sustained price increases and increasing natural gas imports are prompting concerns about this envi- ronmentally friendly fuel, which has become a preferred choice for new power plants over the past decade. natural gas imports have grown from . per cent of us natural gas consumption in to . per cent in , placing us demand for natural gas increasingly under the control of unstable world markets. natural gas prices have been rising as well, partly in response to its increased use for electric power generation. between and , the price of natural gas for power production in the us experienced a sixfold increase. this fuel price upsurge has produced economic downturns in industries that are heavily reliant on natural gas for power production or feedstocks, with chemical manufacturers, paper and pulp mills, and refineries being particularly hard hit. continued natural gas price spikes may reverse the trend away from coal use in power production, raising concerns for carbon dioxide emissions and air pollution. the environmental consequences of such an outcome would be aggravated if today’s nuclear power plants are retired over the next fifty years as their licences expire. renewable sources of electricity show great promise, but their current market penetration is limited to only two per cent of electricity generation (excluding hydropower). as a result of increasing demand for electricity, environmental regulations and rising fuel prices, the cost of electricity is rising. the average retail price of electricity for all customers rose in real terms from . cents per kilowatt-hour in to . cents in . proportionately, twenty-two utilities increased rates for their customers in , and at least forty-one did so in . the end of june saw delmarva power business customers in delaware experiencing rate increases as high as per cent. baltimore gas and electric residential have announced rate increases of per cent. other customers in new jersey will likely see rate increases of per cent, those in florida per cent, those in wisconsin . per cent. compounding these price and fuel reliability issues, the us transmission system con- tinues to experience stress from the combination of increasing power flows and declining grid investments. us expenditures in transmission infrastructure peaked at almost seven billion dollars in , but then declined to less than half that amount annually over the last two decades, although recently the amount has risen again to $ . billion. patrick lanning, the president of a mid-size utility serving eighty-three thousand customers in oregon, recently told investors that his electricity grid was so underfunded that eighty-five per cent of his transmission and distribution poles were at least thirty years old. lanning cautioned that: ‘wires, circuit breakers, substations and other equipment are nearing or have reached the end of their useful life and are in need of replacement or upgrading. if we don’t start taking care of these needs now, reliability will slip below acceptable levels.’ the shortfall in electric transmission investments is contributing to a dramatic increase interdisciplinary science reviews, , vol. , no. marilyn a. brown and benjamin k. sovacool in transmission congestion. requests from system operators for transmission loading relief in the eastern part of the us, for example, rose from around fifty in july to in july and more than in july . similar infrastructure issues pervade the whole us energy system, which is much more extensive and varied today compared with the s. communities are increasingly unwilling to host new energy facilities, as evidenced by the cape wind project off the massachusetts coast, the liquid natural gas terminals proposed for maine and new jersey, and the yucca mountain nuclear repository. as a result, today’s energy infrastructure is in great need of modernisation and expansion. the two indicators of energy efficiency are inconsistent in their directional trends. on the positive side, the consumption of energy has not been expanding as rapidly as the economy has been growing. in the us consumed approximately . kilowatt-hours ( kbtu) per dollar of gdp, while by this measure of energy intensity had dropped to around . kilowatt-hours ( kbtu) per dollar. were it not for this change, the united states would be consuming twice as much energy today, and its energy bill would be a billion dollars per day higher. this energy productivity improvement reflects structural shifts in the economy, away from energy-intensive industry and toward service and information-based jobs. in addition, it reflects the fact that the country has learned to get more for the energy it consumes by investing in more efficient end-use technologies – better appliances, more home insulation, variable speed motor and drive systems in indus- try, and more efficient lighting. the potential for energy efficiency to continue to stretch the nation’s energy resources remains vast, but whether this potential will be tapped is unclear. in contrast to the improving trend in energy productivity, energy use per capita has remained relatively static. based on a metric indexed to . in , energy use per capita remains at about that same level today. hidden within this index are several balancing trends. on the one hand, industrial energy use per capita has declined by more than thirty per cent, largely due to the shift toward a more service-oriented economy. at the same time, industry has moved away from direct combustion of fossil fuels toward greater electrification, including increased use of electric and electronic equipment such as digital controls, telecommunications, computers and peripheral devices, microwave heating and imaging devices. because of these industrial trends and increased plug loads in residential and com- mercial buildings, us electricity consumption per capita has increased more than sixty per cent since , placing greater stress on the power grid. recent data indicate that this growth continues unabated. the eei, for instance, estimated that . million new residential and , new commercial customers were added to the national power grid in , and that the kilowatt-hours consumed per customer grew by . per cent between and . while it is true that remarkable improvements in energy efficiency have contributed greatly to reducing the growth in energy consumption, the historical record suggests that energy efficiency practices and demand-side reduction programmes in most us regions have been unable to offset steady increases in demand. for example, on-site electricity consumption per household in the united states dropped twenty-seven per cent between and , yet the number of households grew by a third. over the same period, interdisciplinary science reviews, , vol. , no. developing an ‘energy sustainability index’ to evaluate energy policy electricity’s share of household energy consumption actually increased from twenty-three to thirty-five per cent. john wilson, a staff member for the california energy commis- sion, put it this way: ‘new californian homes use one sixth of the energy per square foot for air conditioning that they did years ago. the bad news is that homes are almost twice as big as they were years ago. we are making things more efficient, but making more of them.’ many states have demonstrated the potential for aggressive and sustained energy efficiency programmes, such as california where electricity consumption per capita has remained flat while the state’s economy has grown significantly. the challenge is to translate this energy efficiency ‘best practice’ to the rest of the country. similarly, the two indicators of environmental quality are mixed. electricity production and passenger cars and trucks are the largest sources of air pollution (including sulphur dioxide) and greenhouse gas emissions (including carbon dioxide) in the united states. thus, the us energy enterprise has significant impacts on human and ecosystem health. on the one hand, the country has made great progress in reducing air pollution from electricity production as a result of three decades of ‘clean air’ legislation. between and , sulphur dioxide emissions from electricity generation and combined heat and power systems have decreased dramatically from . million tons in to . million in . these reductions were accomplished by installing pollution control devices at coal plants and industrial facilities, relying more on low-sulphur coal, and transitioning to cleaner fuels such as natural gas. similar reductions are now needed to curb particulate matter and nitrogen dioxide emissions and to improve visibility. on the other hand, total us emissions of carbon dioxide from energy consumption have increased significantly from . billion metric tons in to . billion in . put another way, since the us emits a quarter of the world’s greenhouse gases and power plants are responsible for forty per cent of those emissions, american power plants alone today account for a tenth of total world greenhouse gas emissions. while scientists are still refining their knowledge about the link between anthropogenic emissions of greenhouse gases and global climate change, it appears likely that a cause-and-effect relationship is intimately tied to the ways in which we consume energy. clearly, the last thirty years have not produced the low-carbon energy technologies needed for low-cost stabilisation of atmospheric greenhouse gas concentrations. conclusions first – and contrary to many prevailing views – the united states has backslid in terms of energy sustainability. even during the s, at the height of the energy crisis and the pinnacle of public awareness concerning energy, americans increased their energy use. from – , electricity consumption increased by a half, and the consumption of gasoline and total number of miles driven by automobiles increased by a fifth. the price per barrel of oil and the amount of oil the country imports have grown exponentially. the nation’s electricity transmission and distribution networks remain strained and near collapse, and the price of natural gas and retail electricity rates have begun to rise. people consume more energy per capita today than in , and consequently carbon dioxide emissions continue to grow. second, because energy progress is always based on what one measures, we need to develop better ways of conceptualising energy sustainability. we caution that our interdisciplinary science reviews, , vol. , no. marilyn a. brown and benjamin k. sovacool esi (energy sustainability index) is just a start, a preliminary effort to quantify energy sustainability – although our hope is that it will become as important as other often used indicators relating to the quality of the environment, life, health and the economy. given the interrelated nature of energy to each of these activities, a case can be made that energy sustainability is even more fundamentally important. we need better tools to assess the nexus between energy, society and the environment. third and finally, the somewhat bleak outlook for the us underscores the urgency of decisive action regarding energy policy – for both the us and the international community. energy consumption in developed countries now rises in lock-step with population growth. from – , for instance, total consumption of energy in the united states grew . per cent, and the total population of the us grew . per cent. over the next forty years, the united nations estimates that the population of the world will grow at a rate of . per cent each year – more than seventy-five million more people annually – from . billion in to . billion in . if the global demand for energy continues to grow at an analogous rate, then capital investment in energy technologies will need to triple from twelve trillion dollars today to thirty-six trillion by . this means, for better or for worse, that the ‘energy problem’ fretted about in the s has by no means been fully addressed – and that we need to start more coherently talking about energy sustainability. trying to measure the complex interactions between energy and society by using contemporary methods – such as energy intensity or electricity con- sumption – is akin to trying to drive a car with only a fuel gauge, or to seeing a doctor who only checks your cholesterol. whether we decide to metaphorically tap the accelerator, eat more chocolate, or heed the challenge is entirely up to us. acknowledgement assistance with statistical references was provided by michael hamilton, research assistant at the georgia institute of technology, and is gratefully acknowledged. notes . j. r. holmstead: ‘thirty years of clean air progress’, ejournal usa: global issues, , june, – , http:// usinfo.state.gov/journals/itgic/ /ijge/ijge .htm. . p. j. dobriansky: ‘the environment: shared goals and a common mission’, ejournal usa: global issues, , june, – , http://usinfo.state.gov/journals/itgic/ /ijge/ijge .htm. . m. lynch: ‘the new energy crisis: separating threats from hysteria’, energy policy, , , – . . p. l. joscow: ‘markets for power in the united states: an interim assessment’, energy journal, , , – . . b. lomborg: the skeptical environmentalist: measuring the real state of the world, ; , cambridge, cambridge university press. . m. brown: ‘energy myth one – today’s energy crisis is “hype”’, in energy and 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erickson: a practical guide to environmental impact assessment; , san diego, ca, university of california press; a. gilpin: environmental impact assessment: cutting edge for the twenty-first century; , cambridge, cambridge university press. . j. pope, d. annandale and a. morrison-saunders: ‘conceptualizing sustainability assessment’, environmen- tal impact assessment review, , , – ; m. gismondi: ‘sociology and environmental impact assess- ment’, canadian journal of sociology, , , – ; s. payraudeau and h. ven der werf: ‘environmental impact assessment for a farming region: a review of methods’, agriculture, ecosystems and environment, , , – . . j. bentham: introduction to the principles of morals and legislation; , oxford, oxford university press. . r. levett: ‘sustainability indicators – integrating quality of life and environmental protection’, journal of the royal statistical society, , , – . . k. d. haggerty: ‘the politics of statistics’, canadian journal of sociology, , , . . m. nicholson and r. fryer: ‘developing effective environmental indicators – does a new dog need old tricks?’, marine pollution bulletin, , , – . . g. kirk: schumacher on energy: speeches and writings of e.f. schumacher, – ; , london, jonathan cape. . e. a. rosa, g. e. machlis and k. m. keating: ‘energy and society’, annual review of sociology, , , – . . ‘annual energy outlook ’, us energy information administration, washington, dc, january , www.eia.doe.gov/oiaf/archive/aeo . . g. h. brundtland: our common future; , oxford, oxford university press. . k. rennings: ‘economic and ecological concepts of sustainable development: external costs and sustainability indicators’, in social costs and sustainability: valuation and implementation in the energy and transport sector, (ed o. hohmeyer, r. l. ottinger and k. rennings), – ; , new york, ny, springer. . d. w. pearce and g. d. atkinson: ‘capital theory and the measurement of sustainable development: an indicator of “weak” sustainability’, 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reducing human impact on the earth; , gabriola island, bc, new society publishers; l. walker and w. rees: ‘urban density and ecological footprints: an analysis of canadian households’, in eco-city dimensions: healthy communities, healthy planet, (ed. m. roseland); , gabriola island, bc, new society publishers; j. merkel: radical simplicity: small footprints on a finite earth; , vancouver, bc, new society publishers; s. gilson: ‘the influence of development characteristics on the ecological footprint in an urban household’, seattle office of sustainability and environment, seattle, wa, march , www.ci.seattle.wa.us/environment/ose% footprint% report% - - .pdf. . ‘leadership in energy and environmental design’, us green buildings council, www.usgbc.org/leed. . ‘annual energy review ’, us energy information administration, washington, dc, june , table . , http://tonto.eia.doe.gov/ftproot/multifuel/ .pdf. interdisciplinary science reviews, , vol. , no. marilyn a. brown and benjamin k. 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available/etd- - ). . ‘inventory of california greenhouse gas emissions and sinks: – ’, california energy commission, sacramento, ca, november , www.energy.ca.gov/reports/ - - f/ - - _ - - f- es.pdf. . ‘national air quality and emissions trends report, ’, environmental protection agency, washington, dc, , , table a- , www.epa.gov/air/airtrends/aqtrnd ; ‘annual energy review ’, table . a (see note ). . g. marland, t. a. boden and r. j. andres: ‘global, regional, and national co emissions: united states’, in trends: a compendium of data on global change, carbon dioxide information analysis center, oak ridge national laboratory, us department of energy, oak ridge, tn, , http://cdiac.ornl.gov/trends/ emis/tre_usa.htm; ‘annual energy outlook ’, table d (see note ). . s. a. shapiro and j. p. tomain: ‘realizing the promise of electricity deregulation: rethinking reform of electricity markets’, wake forest law review, , , – . . d. nye: consuming power: a social history of american energies; , cambridge, ma, mit press. . a. a. bartlett: ‘facing up to our problem with numbers’, in what every westerner should know about energy, (ed. p. n. limerick), – ; , boulder, co, center of the american west. . united nations commission on population and development, , www.un.org/esa/population/ unpop.htm. interdisciplinary science reviews, , vol. , no. developing an ‘energy sustainability index’ to evaluate energy policy marilyn a. brown (marilyn.brown@pubpolicy.gatech.edu) is professor of energy policy in the school of public policy at the georgia institute of technology. previously she held various leadership positions at oak ridge national laboratory and was an associate professor in the department of geography at the university of illinois, urbana-champaign. she has a phd in geography from ohio state university, a master’s in regional planning from the university of massachusetts, and is a certified energy manager. she has been an expert witness in hearings before committees of both the us house of representatives and the us senate. dr brown serves on the national commission on energy policy, on the boards of directors of the american council for an energy-efficient economy and the alliance to save energy, and on the editorial boards of several journals. benjamin k. sovacool (sovacool@vt.edu) currently teaches in the government and international affairs program at the virginia polytechnic institute & state university in blacksburg, va. he is a former eugene p. wigner fellow at the oak ridge national laboratory in oak ridge, tn, and a senior research fellow at the network for new energy choices in new york. he recently completed work on a grant from the national science foundation’s electric power networks efficiency and security program investigating the social impediments to distributed and renewable energy systems. he also served as a senior research fellow for the virginia center for coal and energy research, where he assessed renewable energy issues for the state of virginia. his most recent book (co-edited with dr brown) is energy and american society – thirteen myths, published by springer in . combating energy poverty in mountainous areas through energy-saving interventions insights from metsovo, greece nikolas katsoulakos katsoulakos@metal.ntua.gr metsovion interdisciplinary research center, national technical university of athens, heroon polytechneiou, zografos athens, greece open access article: please credit the authors and the full source. an increasing number of people find it difficult or even impossible to ensure adequate coverage of their energy needs. this situation, defined as energy poverty, is one of the results of the global energy crisis. mountainous areas are especially vulnerable to energy poverty because their thermal energy needs are especially high and their economic environment is not a particularly prosperous one. we studied ways of reducing conventional fuel use and thus restricting the risk of energy poverty in metsovo, a greek mountain town. given the special characteristics of energy consumption in the area and its energy potential, several alternative scenarios for saving energy in the town of metsovo were constructed. the economic performance of the alternatives and their contribution to combating energy poverty were assessed. it was shown that utilizing locally produced biomass and applying energy-saving measures can bring households below the ‘‘energy poverty limit.’’ moreover, dependence on diesel oil and electricity for heating purposes can be reduced to a very low level by applying financially viable energy practices. the case of metsovo shows that the establishment of an appropriate framework of sustainable energy policy in mountainous areas can bring about significant environmental, social, and financial benefits. the general objectives of the energy strategy of the european union, as well as its efforts to combat energy poverty, can be significantly supported by the rich renewable energy potential of its mountainous areas, which is well illustrated by the example of metsovo. keywords: energy poverty; biomass; energy saving; energy efficiency; renewable energy potential; greece. peer-reviewed: august accepted: september introduction energy production at the global level is based mainly on nonrenewable sources. as their name implies, these sources are finite and exhaustible. economically viable deposits of fossil fuels are becoming rare at the same time that global energy demand is increasing. it is estimated that global energy consumption in will be almost % greater than in , and % of it will be based on fossil fuels (eia ). the impacts of this situation are multidimensional: environmental, economic, social, and political problems emanate from continuously increasing use of fossil fuels. energy poverty is one of the most important issues related to the global energy crisis. there are many approaches to energy poverty. a comprehensive description is contained in an opinion of the european economic and social committee (eesc), published in (p. c / ): energy poverty occurs where a household finds it difficult or impossible to ensure adequate heating in the dwelling at an affordable price … and having access to other energy-related services, such as lighting, transport or electricity for use of the internet or other devices at a reasonable price. there is no standard quantitative definition of energy poverty. however, an approach that is often used is the following: if a household spends more than % of its annual income for energy, it is considered as energy poor (walker ). this ‘‘energy poverty limit’’ was first introduced in the united kingdom. the impacts of energy poverty can be particularly negative. premature deaths from indoor air pollutiondue to wood or coal use in poor households are the sixth largest health risk factor in developing countries (sagar ). according to the united nations, by deaths caused by energy poverty will be more than premature deaths owing to malaria or hiv if no action is taken (lavelle ). hence, several national and international organizations have become concerned about this problem. in the eesc proposed that combating energy poverty should be a new social priority within the european union. mountaindevelopment transformation knowledge mountain research and development (mrd) an international, peer-reviewed open access journal published by the international mountain society (ims) www.mrd-journal.org mountain research and development vol no nov : – http://dx.doi.org/ . /mrd-journal-d- - . � by the authors increase in fuel prices is one of the main factors that intensify energy poverty, although this is virtually inevitable as the result of scarcity of fossil deposits, unstable tax policies, and inefficiencies in the function of the liberalized energy market (bahce and taymaz ; eesc ). thus if no action is taken the problem will intensify as a result of the global energy crisis. improving energy efficiency and promoting renewable sources of energy are the basic steps in combating energy poverty. mountainous areas have common characteristics that make them highly vulnerable to energy poverty. many mountain economies are not particularly robust (funnell and parish ), mountain settlements are usually far away frommajor energy production centers, and thermal energy needs in mountain areas are significantly greater due to cold climatic conditions. especially in greece, mountain communities are threatened by both the global energy crisis and the economic crisis. between december and february , incidents of illegal logging were recorded in mountainous areas of greece (peklaris ), as many people were unable to afford the cost of diesel oil and desperately sought for ways to cover their thermal energy needs. such occurrences, following energy poverty, are common in developing countries (foerster et al ), and it is quite worrying that they are also beginning to appear in the european union. there is a considerable lack of studies on energy- saving potential inmountainous settlements ingreece, as well as on the issue of energy poverty in mountainous greece. the present study is one of the first attempts to compensate for this lack. itsmain objective is to highlight the positive effects of energy saving in cutting the risk of energypoverty inmountainousgreece.themountainous town of metsovo ( u n; u e) was used as a case study (figure ). metsovo is situated in the northern pindos mountain range and lies at an altitude of m. it has about inhabitants, living in households. although it has a rich renewable energy potential, metsovo is vulnerable to energy poverty. mountainous regions, according toeuromontana, ‘‘are an ideal area for reducing energy consumptionwhile maintaining a high standard of living’’ ( : ). bearing this in mind, we have attempted to show that reducing fuel consumption should be a basic part of mountain energy policy. the current economic crisis threatens the standard of living in greece, and in metsovo expenses to meet energy needs are an especially high demand on people’s income. therefore, exploring energy-saving possibilities is necessary in order to preserve positive development perspectives in the area. methodology the improvement of a building’s energy performance is basedonanalysis of its energy consumptionanda techno- economic assessment of available energy-saving solutions. in order to explore the possibilities for reducing energy consumption in metsovo and thus reducing the risk of energy poverty in the town, the methodology used for a single building was generalized. more specifically, the methodology included steps: . collection and analysis of statistical data. thedata analyzed included the thermal and electrical energy consump- tion of the households, according to thegreek energy information system, and the characteristics of the buildings, according to the hellenic statistical au- thority. . field survey related to the energy consumption of the households. the survey aimed to define detailed characteristics of energy consumption in the residen- tial sector (energy systems used, required fuel quanti- ties, technical and geometrical characteristics of the residencies, etc) and was conducted on the basis of personal interviews in . the sample included households. at a confidence level of %, the margin of error of the survey is . %, taking into account that the population (number of households) is . . thermal imaging of houses. the survey aimed to define weaknesses in the shell ofbuildings that lead to thermal losses. it was conducted between february andapril . the sample included houses in age categories (before , – , – , after ). the houses in the same age category present similar technical characteristics and energy performance. . formation of alternative scenarios for reducing energy consumption. five scenarios of different economic and technological intensity were constructed. the alter- natives include energy-saving interventions, biomass, and solar energy utilization. in order to estimate the impacts of the alternatives on energy consumption, a ‘‘model house’’ was created for each age category, to which the energy improvement interventions were applied. following the data analyzed in the first step, the model house was considered to have area and volumeequal to the corresponding average sizes of the buildings belonging to the same age category. the technical characteristics of the ‘‘model house’’ were estimatedaccording toboth the statistical data and the field surveys. . technical and economical assessment of the alternatives. in order to assess the financial performance of the alternatives, a feasibility study was conducted. the feasibility study was based on cash-flow tables, which include the financial benefits, the required investment costs, and the operation and maintenance costs for each alternative. moreover, the contribution of the alternatives toward combating energy poverty was estimated, as well as environmental performance. the central idea behind this study is to apply a methodology followed at a small-scale level (single mountaindevelopment mountain research and development http://dx.doi.org/ . /mrd-journal-d- - . buildings) to a large-scale level (entire town). it was applied for the first time in mountainous greece. the main advantage of this procedure is that it can provide quick and reliable estimates of the effectiveness of several ‘‘green’’ energy practices. moreover, the accuracy of the results is far greater than the estimates currently available at country level. this allows for priorities for regional energy strategies to be set. therefore, this methodology can be a useful tool for policy makers in mountain settlements to identify pathways to combating energy poverty. metsovo energy profile the cold climate in the area around metsovo results in high thermal energy demand, which is significantly greater than in areas at almost the same latitude but at lower altitudes. the mean annual temperature is uc, and the average annual rainfall is as high as mm. heating degree-days are summations of the differences between the average daily temperature and a base temperature, usually considered to be . uc. they are derived from temperature measurements. the thermal needs of a building structure at a given location are directly proportional to the number of the heating degree-days at this location. in figure , the heating degree-days for metsovo and other towns—calculated by the available meteorological data—are presented. energy needs in table the data for energy consumption in metsovo and its environmental and financial impacts are summarized. fuel prices used were: . us$/l for diesel, us$/tonne for firewood, and . us$/kwh for electrical energy. the diesel and firewood prices refer to the average prices of those fuels in greece between october and april . the heating source referred to as ‘‘other’’ is assumed to be a combination of diesel oil heaters, open fireplaces, and electrical heaters, following the results of the field survey. in order to calculate the particulate matter emissions for the heating systems currently used, several estimates were combined (johansson et al ; greenpeace ; eea ; naei ). the co emissions were obtained by the greek public power corporation. according to table , and bearing in mind that the number of households in metsovo is , the average annual thermal energy consumption per household was , kwh, of which % is needed for space heating and % for water heating. the cost of this amount of thermal energy is us$ per year. the thermal energy costs corresponded to . %of the average annual income of the households, which was us$ , . electrical energy consumption—excluding electrical energy consumption forheatingpurposes—was estimated at kwh/household, on an annual basis, following the results of the field survey. this corresponds to us$ figure view of the town of metsovo. (photo by nikolas katsoulakos) mountaindevelopment mountain research and development http://dx.doi.org/ . /mrd-journal-d- - . per year. electricity consumption in metsovo is significantly lower than the corresponding average consumption in greece. energy efficiency of buildings the available statistical data show that % of the total thermal energy demand of the households in metsovo comes from buildings constructed before . the majority of these houses are stone-built, and their insulation standards are very poor. after taking thermal images of the residencies in metsovo and analyzing the statistical data, some useful conclusions were reached (figure ): n houses built before and between and had particularly low energy performance. about % of themwere not insulated, and almost all of themhad obsolescent window frames. these houses need to be insulated, and theirwindow frames shouldbe replaced. n houses built between and had better energy efficiency, mainly due to the fact that their walls were insulated. their thermal losses were mainly attributed to window frames that should be replaced. n the thermal energy demand of houses built after represents only % of the total demand. their energy performance was generally good. so no action for those buildings is proposed. metsovo and energy poverty overall, . % of the households’ annual income was required for energy expenses, taking into account both heating and the electrical energy costs. this percentage was slightly higher than the ‘‘energy poverty limit,’’ which means that metsovo is vulnerable to energy poverty. after a more thorough look at the distribution of household income, it was apparent that a significant number of people already faced great difficulties in covering their energy needs. more specifically, households had annual incomes of less than us$ , . for these people energy expenses represented more than % of their income, meaning that they are obviously not capable of covering their energy needs sufficiently. the greek government has announced that fuel taxes will be dramatically increased in october . diesel oil table thermal energy consumption and its environmental and financial impacts in metsovo. thermal energy system energy consumption (kwh) annual co emissions (tons) annual pm a) emissions (kg) annual cost (us$) ratio of heating costs to households’ income (%) space heating , , , , . diesel oil–fired heaters , , , , wood-fired heaters , , , wood stoves , , , other , , , water heating , , , . boiler heated by diesel oil , , boiler heated by wood , , electrical boiler , , total , , , , . a)pm: particles with a median diameter of less than mm. the amount present in the atmosphere is used as an indicator of the level of pollution. figure heating degree-days of greek towns. mountaindevelopment mountain research and development http://dx.doi.org/ . /mrd-journal-d- - . will rise fromus$ . /l to aboutus$ . /l, an increase of %.thismeans that the averageportionofhousehold income needed for energy expenses will rise to . % in metsovo, not to mention that greek gross domestic product is expected to decrease in . therefore, the problem of energy poverty will be further intensified (especially for low-income households) under the effects of the current economic crisis, so there is a definite need to take action. possibilities of exploiting renewable energy potential and applying energy-saving measures metsovo is surrounded by large forests. between and , the average firewood production was tonne/y, according to the local forestry authorities. this quantity is sufficient to cover the thermal energy needs of about half of the households. so far, only % of the households cover their energy needs with wood- fired systems. therefore, there is an important local biomass potential that can be utilized. it should be noted that the forests are publicly owned and are exploited on a cooperative basis. the annual portion of solar irradiation in the area of metsovo is kwh/m on a horizontal plane (pvgis, ). this important solar energy potential is practically unutilized in metsovo. solar systems are not used in the town, because of legal restrictions that aim to protecting the vernacular architecture of the town. so incorporating renewable technologies in traditional buildings—with consequent revision of current legislation—is a prerequisite for taking advantage of solar energy. as far as energy saving is concerned, interventions in the buildings’ shell are necessary to lower thermal loads. according to the technical chamber of greece ( ), improving the shell of a building can have the following results: n thermal insulation of walls: – % energy savings; n replacement of window frames: – % energy savings. alternative scenarios for lowering energy consumption in order to devise a strategy formore rational energy use thatwill help to confront energypoverty, it is necessary to create alternative scenarios of varying economic and technological intensity. in accordance with the special characteristics of metsovo, alternatives have been created (see box ). the investment costs for each alternative, the economic benefits, the external benefits (monetary value of the environmental benefits), and the contribution to reducing conventional fuel use are given in table . calculation of external benefits was based on butti et al ( ) and the results of the externe research project. the investment costs were estimated after a thorough search of the energy products market in greece and by taking into account themodel house in eachage category. taking the age category ‘‘before ’’ as an example, the model house has the following characteristics: n area: . m ; volume: . m ; area of openings: . m ; number of floors: ; n shell construction materials: stone; construction ma- terials for openings: wood; insulation: none. figure distribution of thermal energy demand in metsovo versus buildings’ age (according to the greek energy information system). box : alternative scenarios for reducing conventional fuel use in metsovo alternative : installation of solar collectors for hot water heating. this option includes the installation of solar systems in households using diesel oil–fired and electrical boilers. alternative : installation of domestic biomass–fired heaters. this scenario includes the replacement of diesel oil–fired heaters with biomass heaters. locally produced biomass can cover the needs of households. alternative : thermal insulation of walls and replacement of window frames. this option promotes energy-saving interventions in the building shell. thermal insulation would be added to residences built before , and replacement of window frames would be applied to houses built prior to . alternative : building shell improvement and use of domestic biomass–fired heaters. this is a combination of alternatives and . alternative : building shell improvement, use of domestic biomass–fired heaters and installation of solar collectors. this is the most complex scenario that combines alternatives and . mountaindevelopment mountain research and development http://dx.doi.org/ . /mrd-journal-d- - . assessment of the alternatives a feasibility study was conducted for financial evaluation of the alternatives. the lifetime of the investments was taken tobe years, and thediscount ratewas considered to be % (christodoulou ). the criteria of the net present value (npv), the internal rate of return (irr), and the payback period (pp) have been used. the feasibility study was supplemented with estimates of the contribution of the alternatives toward combating energy poverty. the ratio of the annual energy expenses to the average household’s income is calculated following each energy intervention (table ). all the investments hadpositivenpv, irrhigher than the discount rate, and pp less than years, which is considered to be their lifetime. the increased thermal energy needs of mountain settlements in combination with high diesel oil prices were the main reasons for the good financial performance of the energy-saving interventions. the replacement of diesel oil–fired heaters with biomass heaters had remarkably good financial performance and seemed to be the most efficient intervention for reducing fuel costs in metsovo. apart from the direct economic and environmental benefits, forest biomass exploitationhas broaderpositive results in mountainous areas. more specifically, the existence of forest production can contribute to forest revitalization and creation of workplaces. the assumptions about the lifetimeof the investments and the discount rate were in accordance with the corresponding assumptions commonly made for energy- saving projects in greece. however, a sensitivity analysis was carried out in order to assess the influence of the discount rate on the performance of the alternatives. as depicted in table , a variation of % in the discount rate did not seem to have a very significant influence on the investments’ performance. all of the alternatives remain viable, and of thempresent a year’s increase in the pp if the discount rate grows by %. the prices of the fuels proved to be more important for theviabilityof the investments. inparticular, theprice of diesel oil had a more intense influence on the performance of the alternatives. for example, in the case of applying thermal insulation to the shell and replacing the window frames, if the diesel oil price decreases %, then the pp increases from to years, and the npv shrinks to % of the initial value. figure shows the impacts of the variation of the diesel oil price, the firewood price, and the discount rate on the pp of the second alternative (use of domestic biomass heaters). nevertheless, the contribution of the alternatives to combating energy poverty cannot be based solely on economic performance. the use of biomass heaters reduces the percentage of energy expenses to . % of annual income. combining biomass heaters with energy- saving interventions brings about further reduction, and the ratio percentage drops to . %.adding solar systems table financial costs and benefits, external benefits, and reduction in conventional fuel use for each alternative. alternatives investment cost (us$) annual economic benefit (us$) annual external benefit (us$) reduction in conventional fuel use (%) , , , . , , , , . , , , , . , , , , . , , , , . table economic performance of the alternatives and ratio of thermal energy expenses to the households’ income.a) alternatives npv (us$) irr (%) payback period (y) thermal energy expenses to household income ratio (%) , . , , . , , . , , . , , . a)npv: net present value; irr: internal rate of return. mountaindevelopment mountain research and development http://dx.doi.org/ . /mrd-journal-d- - . for hot water production reduces the percentage to the minimumpossible value of . %. it should be noted that the fifth alternative was of significant help for the financially weakest part of the town ofmetsovo. people obliged to spend %of their income forenergywouldbe greatly relieved after applying this alternative, since they wouldneed to spendabout %of their income.however, this amount is still higher than the energy poverty limit, and under current conditions, people with low incomes need support to cover their energy needs sufficiently. as far asenvironmentalperformance is concerned, it is obvious that themost complex alternative has themost positiveenvironmental impact.thefifthalternativeresults invery lowdependenceonconventional fuel,at the levelof %.thealternativewith thebest economicperformance also showedgoodenvironmentalperformance, resulting in about a %reduction in conventional fuel use andco emissions.widening the use of biomassmay also have negative environmental consequences related to the increase in particulatematter emissions, even if the new biomassheaters follow strict standards suchas theen - .however, due to meteorological conditions inmetsovo, which includenandnwwindswithvelocitiesover m/sec ona regularbasis, this slight increase inparticulatematter emissions is not expected to affect the environmental quality of the air. conclusions it is clear that increased fuel use in mountainous areas make them particularly vulnerable to energy poverty, owing to the harsh weather conditions. as illustrated in the case of metsovo, by applying the proposed methodology, pathways leading to combating energy poverty can be found. mountainous areas should overcome the risk of becoming ‘‘energy poor,’’ asmany of them are situated in locations that are ‘‘energy rich.’’ in metsovo, expanding the use of domestic, biomass- fired heaters resulted in high financial performance and helped to reduce conventional fuel use. this constitutes a solution with reasonable investment costs and direct positive effects on reducing energy expenses. a more integrated solution, with greater effects on energy poverty, would be a combination of biomass use with energy-saving interventions. this strategy can have more positive consequences on a long-termbasis. however, the required investment costs are particularly high (figure ). it seems that a policy providing financial incentives to apply energy improvement interventions is necessary to improve the metsovo energy profile. the greek government has designed a program, called ‘‘save at home,’’ that promotes energy saving by providing subsidies to specific categories of households. more specifically, the houses eligible for energy improvement are those built before in areas with relatively low land prices. state support is of significant help to householdswith annual incomes less thanus$ , and includes a % subsidy and a % interest-free loan. a disadvantage of the ‘‘save at home’’ program is the fact that it does not include a criterion related to the intensity of energy demand. it is reasonable that areas with increased energydemand shouldhaveprioritywhere energy improvement is concerned, but this is not part of the current energy-saving policy. therefore, greek mountainous settlements are not receiving significant assistance in changing their energy profile. since table variation in the payback period of the alternatives with respect to changes in the rate of return. alternatives payback period (y) rate of return % . % % . % % figure sensitivity analysis related to alternative (use of domestic biomass heaters). mountaindevelopment mountain research and development http://dx.doi.org/ . /mrd-journal-d- - . mountainous areas are more vulnerable to energy poverty, it is clear that a special energy policy framework should be created for them. the economic and environmental benefits of applying sustainable energymeasures inmountainous areas arenot only of local importance. it should be noted that reduction of conventional fuel use could reach almost % in metsovo. this has far more positive effects than the ‘‘ – – ’’ objective. the economic effects are not only important for local society, but also for thegreek economy in general. diesel oil demand in greece—and in the majority of european countries—is basically covered by imports, with consequent macroeconomic impacts. therefore, every action that reduces dependence on diesel oil has a generally positive result in economic terms. in conclusion, taking into account the analysis done for metsovo, several key factors of interest to mountain areas in general can be highlighted: n energy poverty is a serious social issue and combating it should become one of the main priorities of mountain policy, since mountain settlements are particularly vulnerable to it. n utilization of locally available biomass is a key to lowering fossil fuel consumption for heating purposes inmountainous areas, provided that the productionof firewood follows the principles of sustainable forestry. however, the whole procedure of biomass production, even under the principles of sustainability, can have multiple impacts on the forest ecosystem. hence, further research is needed in this field in order to minimize the side effects of biomass use. n special financial incentives should be given to moun- tain populations to apply energy-saving measures. the economic and environmental effects of such a policy can be highly positive, at the local level and beyond. n mountain communities such as metsovo could be assisted in implementing a sustainable energy policy through knowledge exchange with communities that have applied successful energy strategies, like trento in italy. creating communication networks between mountainous areas is a prerequisite for effective knowledge transfer. eu-funded programs, such as cost, can be utilized to this end. the case of metsovo shows that the economic crisis should not be an excuse for inaction. on the contrary, mountain communities can overcome the impacts of the problem of covering energy needs by promoting of the basic elements of the energy strategy proposed by euromontana for mountain areas: n energy efficiency to the greatest extent possible; n energy production at local level from diverse re- sources. acknowledgments the author thanks mrs aggeliki theodorou, postgraduate student in the msc ‘‘environment and development of mountainous areas’’ of the national technical university of athens, for providing the thermal images and her valuable help in analyzing statistical data. figure investment costs and contribution of each of the alternatives toward mitigating energy poverty. mountaindevelopment mountain research and development http://dx.doi.org/ . /mrd-journal-d- - 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national specifications of parameters needed to estimate the energy performance of buildings and to issue the certificate of energy performance [in greek]. technical instruction – / . athens, greece: technical chamber of greece. walker g. . decentralized systems and fuel poverty: are there any links or risks? energy policy : – . mountaindevelopment mountain research and development http://dx.doi.org/ . /mrd-journal-d- - . finaldoc.pdf c e p a l review director r a u l p r e b i s c h technical editor a d o l f o g u r r i e r i u n i t e d n a t i o n s economic commission for latin america santiago, chile / december c e p a l review n u m b e r d e c e m b e r c o n t e n t s n o t e b y the e d i t o r p r e s e n t d e v e l o p m e n t styles and environmental problems mostafá k. tolba t h e interaction b e t w e e n styles of d e v e l o p m e n t and the environment in latin america osvaldo sunkel c o m m e n t s on the article " t h e interaction b e t w e e n styles of d e v e l o p m e n t and t h e e n v i r o n m e n t in latin america" c o m m e n t s b y aníbal pinto c o m m e n t s by jorge sábato c o m m e n t s by gabriel valdés c o m m e n t s by jorge wilheim b i o s p h e r e and d e v e l o p m e n t raúl prebisch t h e e n v i r o n m e n t in the political arena marshall wolfe d e v e l o p m e n t strategies with moderate energy requirements p r o b l e m s a n d a p p r o a c h e s ignacy sachs d e v e l o p m e n t and environment: the brazilian case fernando h. cardoso t h e e n v i r o n m e n t a l d i m e n s i o n in agricultural d e v e l o p m e n t in latin america nicolo gligo e n v i r o n m e n t a l factor, crisis in the centres and change in i n t e r n a t i o n a l relations of the peripheral countries luciano tomassini c o m m e n t s on peripheral capitalism and its transformation c o m m e n t s b y lucio geller c o m m e n t s by josé ibarra c o m m e n t s b y p e d r o vuskovic f ' cepal review april d e v e l o p m e n t strategies with moderate energy requirements problems and approaches ignacy sachs* in this short article, t h e author seeks to outline his c e n t r a l ideas on t h e energy crisis. fundamentally, h e s t r e s s e s that t h e crisis has three d i m e n s i o n s : the f i n i t e n e s s of natural resources and t h e deterioration of t h e e n v i r o n m e n t , criticism of the " c o n s u m e r soci- e t y " a n d t h e rising cost of p e t r o l e u m . u n d e r these c i r c u m s t a n c e s , it is u r g e n t to formulate and imple- m e n t d e v e l o p m e n t strategies b a s e d on moderate e n e r g y r e q u i r e m e n t s . t h e p o s s i b l e options are varied, as are the policy m e a s u r e s w h i c h m i g h t b e a p p l i e d ; in this connexion, h e d e s c r i b e s six levels for acting upon the d e m a n d for e n e r g y , r a n g i n g from t h e elimination of waste to a p r o f o u n d c h a n g e in values which would make pos- s i b l e a 'different t y p e of d e v e l o p m e n t ' based on the transformation of t h e prevailing life styles. among o t h e r actions a i m e d at affecting t h e d e m a n d for e n e r g y (to w h i c h h e attaches t h e greatest impor- t a n c e ) , h e m e n t i o n s t h o s e relating to spatial organi- zation a n d t h e readaptation of transport systems. w i t h regard to actions to influence supply, h e s t r e s s e s t h e i m p o r t a n c e of technological pluralism w h i c h w o u l d allow e n e r g y sources to b e d e v e l o p e d a n d u t i l i z e d in the m a n n e r b e s t suited to each nation- a l , r e g i o n a l o r local situation b y avoiding t h e un- critical a d o p t i o n of inappropriate energy strategies. it is n o t easy to formulate and carry out innovative s t r a t e g i e s w h i c h c o m b i n e t h e characteristics of ef- ficiency, v i a b i l i t y a n d sustainability in the econom- ic, socio-rolitical a n d ecological s p h e r e s , but this is an u n a v o i d a b l e necessity for t h e present. •director of the centre international de recherche sur l'environnement et le développement, ecole des hautes etudes en sciences sociales, paris. i the three energy crises t h e e n e r g y crisis is o n t h e agenda of all discus- sions r e g a r d i n g t h e future of the world econo- my, t h e n e w international economic order a n d national d e v e l o p m e n t strategies. in fact, w e a r e facing t h r e e separate b u t coincident c r i s e s . t h e ecological awareness which devel- o p e d o v e r t h e last two decades m a d e it very c l e a r that, in t h e final analysis, the ecological l i m i t s to u n i n t e r r u p t e d economic growth may b e manifested through undesirable and dan- g e r o u s c h a n g e s in climate and in the major natural cycles as a result of the excessive a m o u n t of carbon dioxide released into the a t m o s p h e r e by the combustion of fossil fuels. n u c l e a r e n e r g y in turn raises well-known q u e s t i o n s , to w h i c h w e are far from having reli- a b l e a n d reassuring answers. t h e r e is n o reason to accept t h e apocalyp- tic vision of t h e i m m i n e n t disappearance of c o n v e n t i o n a l energy resources, nor to an- n o u n c e that ecological disaster is nigh. w e are still a l o n g way from t h e outer limits, if they exist. n e v e r t h e l e s s , on ecological grounds a d r a s t i c c h a n g e m u s t take place in man's behav- iour in t h e u s e of fuels and all other potentially scarce, n o n - r e n e w a b l e resources whose extrac- t i o n r e q u i r e s increasing quantities of energy d u e to t h e d e p l e t i o n of more conveniently lo- c a t e d , h i g h - c o n t e n t mineral reserves. w e must d r a w t h e necessary conclusions from the finite- n e s s of o u r p l a n e t , of w h i c h w e h a v e b e c o m e vividly a w a r e , in a historical paradox, as a result of m a n ' s first flights to t h e moon. in t h e long t e r m , t h e survival of the h u m a n race will d e p e n d on its ability to moderate and make m o r e efficient t h e u s e of fuels, and to replace t h e m b y o t h e r forms of r e n e w a b l e energy. o u r p e r i o d marks t h e start of a transition to an industrial civilization based on the direct or i n d i r e c t u s e of solar e n e r g y , which alone can b e u s e d continuously. t h e challenge is w h e t h e r this transition will r e p r e s e n t a step backwards in t e r m s of social justice and the material well- b e i n g of all p r e s e n t and future inhabitants of t h e p l a n e t . t h i s implies more e q u i t a b l e access to b o t h r e n e w a b l e and non-renewable re- cepal review n.° / december sources, and their rational use from a very broad social standpoint based on ethical princi- ples of synchronic solidarity with the present generation as well as diachronic solidarity with future generations, thus transcending the narrow, profit-oriented approaches and depre- datory attitudes to resources stemming from the pursuit of immediate economic gains that do not take social and ecological costs into consideration. the second crisis, closely connected with the first, is that of the 'consumer society' based on the squandering of abundant and cheap energy resources without which both the large- scale production of fairly abundant manufac- tured articles and life styles characterized by the private automobile and the widespread use of air transport would be impossible, interna- tional cultural and consumption patterns have had an enormous demonstration effect on the élites of the third world, with well-known social consequences: the transplanting of highly capital- and energy-intensive technol- ogies, which are the only ones available for producing this basket of consumer goods and which displace the labour force and aggravate still further the inequitable distribution of in- come. thus, within the periphery the imitative model of growth may be seen to incorporate an element of structural crisis which the availabil- ity of cheap energy has accentuated in the extent to which it led to the replacement of locally abundant factors of production by other imported ones. significantly, the consumer society began to be questioned even in the central countries, although for ethical and ideological reasons there, because of its inability to solve pressing social problems despite radical changes in styles and standards of living caused by un- precedented economic expansion during the second half of the twentieth century, as well as the high ecological and psychological cost of accelerated urbanization. quality of life is not necessarily a function of income levels or per capita energy consump- tion, although these factors should not be un- derestimated. the industrialized countries confronted the latest recession without solving various structural problems: the trend towards chronic unemployment, which is also the result of the excessive replacement of labour by energy and the lack of social control over the direction of technological progress; the high cost and inefficiency of welfare state institu- tions; the disorientation of educational sys- tems; a general sense of alienation, etc. far from being an exclusive characteristic of the third world, the negative aspects of develop- ment are universal and may coexist perfectly well with periods of rapid growth, high average levels of income and a type of energy consump- tion which places thousands of 'mechanical slaves' at the service of each citizen. even where it was considered desirable, the consumer society model lost a great deal of its viability due to the third energy crisis after caused by the considerable increase in relative petroleum prices and, by extension, the cost of all energy sources as a result of the action taken by opec. the time of cheap energy came to an end. following the latest decisions by opec ( ), the relative price of petroleum more than made good the losses suf- fered between and , and everything indicates that the trend towards moderate in- crease will continue. an initial result of the growing cost of pe- troleum was to make several alternative energy sources, both conventional and non-conven- tional, economically viable. trends in the in- stallation costs of nuclear power stations are a case in point. solar energy, for its part, will never be cheap; its ecological and social advan- tages must be offset by a fairly high economic price. thus, a fundamental characteristic of the current transition is that, for the first time in history, the replacement of one source of ener- gy by another will be the opposite of what took place in the past with coal in relation to fire- wood, and subsequently, with petroleum in relation to coal: the new energy sources will be considerably more expensive. under these circumstances, energy must be saved and we must learn to use it efficiently and to take advantage of its alternative sources in all countries; this applies even to the major oil producers and exporters which are interest- ed in maximizing their foreign exchange earn- ings and/or preserving hydrocarbon reserves development strategies with moderate energÏ requirements / ignacy sachs with a view to future price increases. the argu- ment applies a fortiori to the countries which import petroleum, many of which face balance- of-payments difficulties due to the growing cost of importing energy resources. the current situation accordingly gener- ates a great deal of tension between the third world countries affected by the high cost of energy imports and the smaller group of major petroleum exporters among them. this tension may be lessened, if not totally eliminated, by more decisive solidarity from opec aimed at assisting the most hard-hit countries. at the same time, however, a double platform of com- mon interests among all the third world coun- tries is emerging. on the one hand, opec's action has political implications which go far beyond the problem of petroleum prices: it fos- ters new conditions for the third world's dif- ficult struggle for effective control over its natural resources. on the other, the third world could very well use this transition to- wards renewable energy sources and the use of biomass as raw material in order to create the basis for a new tropical industrial civilization adapted to its ecosystems and founded on local technologies, or at least less dependent for technology on the major industrial centres which previously achieved world domination through the coal and petroleum civilization, and are now trying to maintain it through a monopoly of nuclear technologies. with the financial resources from sales of petroleum and the human resources already available in sev- eral third world countries, a broad interna- tional research and experimentation program- me could be set up aimed at new and innova- tive forms ofusing renewable natural resources to satisfy social needs within an eco-develop- mental perspective, that is to say, socially des- irable, economically viable and ecologically sound development. ii energy and development strategies it's an ill wind that blows nobody good. the energy resource crisis calls for a comprehen- sive overhauling of development strategies rather than sectoral responses. actions aimed at improving supply are certainly an important aspect of the problem, but by no means the only one. actions with respect to demand have per- haps even greater potential. in other words, itis not a question merely of replacing expensive and/or scarce petroleum by the provision of other energy resources in a classic operation of import substitution, accepting the coefficient of elasticity of demand for energy resources, estimated using past performance, as a limit. on the contrary, an effort must be made to dis- sociate the growth rate of the economy from the rate of increase of the demand for energy re- sources. this implies that the global strategy must be redefined, for the simple reason that energy plays a part in all human activities and consequently it is part of any development pro- cess, sound or unsound. consequently, our problem becomes that of identifying develop- ment strategies with moderate energy resource requirements. the first task is to determine the levels at which the options will be explored and wherein lie the principal variables linking so- cioeconomic development objectives with those involving the moderate use of energy. we will begin by presenting a possible approach to the analysis of the various ways to moderate demand, a subject which deserves attention for two reasons: it is much less developed than the study of the range of alternative energy sup- plies, and it is a good way in which to approach the overall problems which interest us here. next we will discuss the energy implications of models of territorial occupation and of relations between higher and lower economic levels. finally, we shall talk about technological plu- ralism in energy production and the criteria which must govern the selection of technology. we do not aim to provide a solution in these p a g e s , b u t rather to furnish a list of problems c o n n e c t e d w i t h t h e formulation of strategies w i t h m o d e r a t e e n e r g y resource requirements. . six levels of action to affect demand h o w far is it p o s s i b l e to restrict t h e d e m a n d for e n e r g y p r o d u c t s w i t h o u t simultaneously re- q u i r i n g from t h e population radical changes in life styles a n d austerity for which it is not p r e p a r e d ? t h e r e is no easy r e s p o n s e to this question b e c a u s e in societies characterized by pro- n o u n c e d social asymmetry it is hardly possible to s p e a k of t h e population as a homogeneous w h o l e . t h e austerity imposed on the minority m a y b e t h e p r e r e q u i s i t e for improving the con- s u m p t i o n p a t t e r n s of t h e majority. o n the other h a n d , it is simplistic to think that the reduction of t h e d e m a n d for e n e r g y requires either a radi- cal c h a n g e in life styles or a decrease in con- s u m p t i o n . t h e dissociation of economic g r o w t h rates from energy d e m a n d may b e a c h i e v e d t h r o u g h t h e six types of action out- l i n e d b e l o w : (a) t h e elimination of waste in the strict s e n s e of t h e term, through increased social and i n d i v i d u a l d i s c i p l i n e ; (b) i m p r o v e m e n t of t h e functioning of e x i s t i n g p r o d u c t i o n and consumption systems t h r o u g h m o r e efficient organization, education w i t h social content, application of software, or- g a n i z a t i o n of t i m e , etc. (c) t h e r e s t r u c t u r i n g of t h e production sys- t e m w i t h a v i e w to saving energy, either direct- ly t h r o u g h n e w technology or indirectly t h r o u g h t h e materials u s e ; (d) t h e r e s t r u c t u r i n g of t h e consumption s y s t e m b y d e s i g n i n g products (automobiles, e l e c t r i c a l h o u s e h o l d appliances, dwellings, etc.) m e e t i n g l o w e r energy-consumption stan- d a r d s ; (e) t h e exploration of alternative means of m e e t i n g t h e s a m e social n e e d s ; for example, i t h e introduction of t h e concept of the consumption s y s t e m i s j u s t i f i e d b y symmetry with t h e production system a n d b y t h e fact that t h e h o u s e h o l d goods it comprises re- d u c e savings by c o m p e t i n g with investment in the produc- tion sector. c e p a l review n.° / december a l t e r n a t i v e systems of transport or collective or i n d i v i d u a l h o u s i n g . (f) finally, a change in values, which may modify b e h a v i o u r and consequently the struc- t u r e of social d e m a n d . i n c l u d e d h e r e are all efforts to promote voluntary austerity, self-limi- tation of t h e currently excessive levels of mate- rial c o n s u m p t i o n , migration back to rural areas b y g r o u p s of urban residents, etc. various types of actions are appropriate at different levels. levels (a) and (b) in principle d o n o t r e q u i r e any significant investment: they b e l o n g to t h e s p h e r e of ' p u r e ' technological a n d organizational progress. on the other hand, t h e types of technological progress envisioned in levels (c) a n d (d) do r e q u i r e changes in plant a n d e q u i p m e n t a n d a continuous effort to re- search a n d d e v e l o p n e w processes and prod- u c t s . c o n s e q u e n t l y , they correspond to situa- tions of rapid growth and add two n e w d i m e n - sions to t h e criteria for evaluating technology: t h e e n e r g y c o n t e n t of the products and t h e en- ergy c o n s u m p t i o n standards of the goods pro- d u c e d . l e v e l (e) has common characteristics w i t h (d) a n d (f). like level (f), it already implies a c h a n g e of values, b u t it also d e p e n d s on the d e s i g n of n e w consumption systems, that is to say, an extension of t h e approach applied to the d e s i g n of n e w products. in practice, an impor- t a n t d i m e n s i o n to consider is the comparison b e t w e e n systems of collective and individual transportation, housing and organization of s e r v i c e s , a l t h o u g h t h e r e is also room to imagine n e w individual systems, from the widespread u s e of t h e bicycle to t h e invention, in countries a l r e a d y possessing an extensive road infra- s t r u c t u r e , of a n e w u r b a n vehicle, electrical or m e c h a n i c a l , and m u c h smaller and more eco- nomical than t h e automobile. this last level is b y far t h e most important from the point of view of e t h i c s a n d ideology; simultaneously, how- e v e r , it is t h e most difficult to change in view b o t h of t h e conservative dynamism of the élites in p o w e r a n d t h e force of attraction exercised b y t h e c o n s u m e r i s t model on those still living far b e l o w t h e levels of e v e n basic satisfaction of t h e i r material n e e d s , a n d w h o rightly aspire to a m i n i m u m of comfort. this attraction explains t h e distortions in t h e consumption patterns of t h e u r b a n population in latin america, w h e r e development strategies with moderate energy requirements / ignacy sachs d u r a b l e goods, i n c l u d i n g a u s e d automobile, a r e often a c q u i r e d at t h e e x p e n s e of a sacrifice i n v o l v i n g an e v e n greater deterioration in the a l r e a d y low levels of n o u r i s h m e n t . t h e propos- al of following a p a t h differing from the histori- cal e x p e r i e n c e of t h e industrialized countries, a n d t h u s a v o i d i n g t h e d e a d e n d s of consumer- ism w h i l e finding a different type of develop- m e n t , s e e m s to b e the greatest c h a l l e n g e , and an a l t e r n a t i v e to t h e technological optimism of t h e a d v o c a t e s of m i m e t i c growth. but criticism of t e c h n o l o g i c a l o p t i m i s m must not lead to e x a g g e r a t e d social optimism. t h e road leading to a different t y p e of d e v e l o p m e n t will b e r o u g h a n d long. t h e significance of t h e q u e s - t i o n i n g of t h e c o n s u m e r i s t model in the indus- trial c o u n t r i e s t h e m s e l v e s is e n h a n c e d in this w o r l d context. . spatial organization and the energy field s p a c e is a key variable in t h e energy field, e s p e c i a l l y in countries with large areas, b e - c a u s e t h e t r a n s p o r t sector is a great c o n s u m e r of e n e r g y s i n c e t h e v o l u m e of freight and the dis- t a n c e o v e r w h i c h it is transported d e p e n d s on t h e spatial configuration of the economy and t h e society. t h i s situation is aggravated by the t y p e of t r a n s p o r t s e l e c t e d , as latin america suffers from u n d e r d e v e l o p m e n t in the field of railway, river a n d maritime transport, whereas b o t h t h e truck a n d t h e p l a n e occupy an unwar- r a n t e d position as a result of a mistaken and i m i t a t i v e c o n c e p t i o n of modernity. f o r t h e s e r e a s o n s , it is necessary to analyse transport flows, c o m b i n i n g t h e approaches of socioeco- n o m i c p l a n n i n g and spatial organization so as to isolate t h e points at which intervention is p o s s i b l e . t h e g e o g r a p h y of transport m u s t not b e a c c e p t e d as i m m u t a b l e ; on the contrary, it m u s t b e c h a n g e d b y e l i m i n a t i n g r e d u n d a n t t r a n s p o r t a t i o n as far as possible. h e r e w e see a n o t h e r i n s t a n c e w h e r e action to affect d e m a n d is of g r e a t e r i m p o r t a n c e than more traditional action to affect s u p p l y and the technological r e s t r u c t u r i n g of transport systems. h o w d o e s o n e define r e d u n d a n t freight flows? t o do so w o u l d r e q u i r e an in-depth s t u d y on t h e d e g r e e of internal articulation in local e c o n o m i e s a n d t h e nature of their external r e l a t i o n s w i t h t h e regional, national a n d world e c o n o m y . t h e extreme models, both equally harmful, a r e an archipiélago of totally autarkic local e c o n o m i e s , and the centre-periphery m o d e l , not only on a world scale b u t also repro- d u c e d at t h e national level. t h e p e r i p h e r y is c o m p l e t e l y subordinated, and trade is asym- m e t r i c a l : t h e p e r i p h e r y provides raw material a n d d e p e n d s heavily on the centre with regard to c o n s u m p t i o n , i n c l u d i n g that of basic food- stuffs. t h i s results in an extremely high volume of transport, a n d c o n s e q u e n t l y of consumption of e n e r g y resources, which could b e r e d u c e d t h r o u g h t h e consolidation of the local econo- m i e s so as to take maximum advantage of t h e c o m p l e m e n t a r y nature of various primary and s e c o n d a r y activities, while at the same time e n h a n c i n g t h e d e g r e e of processing in the case of r a w materials. t h e asymmetrical relations b e t w e e n t h e c e n t r e a n d t h e p e r i p h e r y and the dominant position of t h e major industrial and commercial systems h a v e another c o n s e q u e n c e for the l e v e l of supply: t h e underestimation of the p o t e n t i a l of local resources which, u n d e r eco- n o m i c a l l y satisfactory conditions, are able to s u s t a i n small-scale production which would d e c r e a s e t h e d e g r e e of d e p e n d e n c e on the ex- terior. t h i s w o u l d certainly b e the case in the p r o d u c t i o n of e n e r g y resources. w h e n , for e x a m p l e , a unified electricity grid fed by h u g e hydroelectric or nuclear power stations is e n v i s i o n e d , m a n y local opportunities are over- looked: small hydroelectric plants, small-scale coal m i n i n g , organic r e s i d u e s from crop-farm- i n g a n d stock-raising production, urban resi- d u e s , t h e specific biomasses of each ecosystem, g e o t h e r m a l e n e r g y and w i n d energy w h e r e climatic conditions permit, specific uses of solar e n e r g y , etc. . technological pluralism t h i s leads us to the third group of variables in t h e field of e n e r g y supply. w e should warn that s i n g l e a n d perfect solutions do not and will not exist. it is necessary to learn to use the broadest p o s s i b l e range of technological pluralism, from t h e s t a n d p o i n t of primary energy sources, scales of production and t h e adaptation of spe- cific forms of supply to a d e m a n d which has b e e n t h o r o u g h l y analysed in order to distin- cepal review n.° / december g u i s h various types of useful energy. t h e anal- ysis of e n e r g y options cannot b e subordinated solely to narrow economic criteria. t h e social a n d ecological implications of the p l a n n e d projects a n d p r o g r a m m e s must also b e consid- e r e d , a n d conventional conclusions must b e g u a r d e d against. certain forms of utilizing re- n e w a b l e e n e r g y may have adverse ecological a n d social repercussions. examples are hardly n e c e s s a r y : dams constructed without taking t h e n e c e s s a r y ecological precautions; large- scale u s e of biomass energy which may dis- p l a c e s u b s i s t e n c e crops while making agricul- t u r e i n o r d i n a t e l y technical a n d capital-inten- sive; t h e formulation of ultrasophisticated c e n t r a l i z e d systems of tapping solar energy by s a t e l l i t e s , etc. technological determinism m u s t n o t b e a c c e p t e d in any form. t h e dogma of e c o n o m i e s of scale has already caused much h a r m in t h i r d world countries, b u t this does not justify r e p l a c i n g it with the myth of 'soft' tech- n o l o g y w h o s e w e a k n e s s e s are belied by al- l u r i n g definitions. d u e t o a series of circumstances, t h e difficult b u t e s s e n t i a l task of mobilizing public opinion in favour of a 'different type of d e v e l o p m e n t ' m a y t a k e t h e form of a search for d e v e l o p m e n t s t r a t e g i e s w i t h m o d e r a t e energy r e q u i r e m e n t s . m e a n w h i l e , w e primarily n e e d a b e t t e r under- s t a n d i n g of t h e links b e t w e e n the variables in t h e e n e r g y s p h e r e , as t h e y have b e e n defined in this work. a good way to achieve this goal m i g h t b e t o c o n s i d e r t h e major production a n d c o n s u m p t i o n systems from this point of view, that is to say: ( ) u r b a n systems and their energy pro- files; ( ) industrial systems; ( ) i n t e g ra t e d food production systems; ( ) e n e r g y systems, stressing the ecologi- cal, social a n d e n e r g y cost of producing and t r a n s p o r t i n g e n e r g y ; ( ) strategies of territorial occupation, re- an initial step in the desired direction w o u l d b e to consider existing energy flows in such a way as to allow them to b e rationalized from t h e standpoint both of d e m a n d (elimina- tion of w a s t a g e , profitability of waste heat) a n d of s u p p l y (replacement of conventional energy b y solar p o w e r ; simultaneous generation of h e a t a n d electricity). it is likewise necessary to p u r s u e technological research on non-conven- tional e n e r g y sources while the social sciences c o n c e n t r a t e on the study of the institutional, e c o n o m i c a n d social obstacles to the introduc- tion of n e w e n e r g y sources, and of t h e policy i n s t r u m e n t s that w o u l d b e r e q u i r e d to promote t h e m effectively. t h e efficient m a n a g e m e n t of technological pluralism will d e p e n d upon t h e s t r e n g t h e n i n g of local autonomy in rural and u r b a n z o n e s . at the same time the harmoniza- tion of local initiatives calls for central planning c a p a b l e of maintaining a global, long-term v i e w of t h e p r o b l e m s and also able to support a n d p r o m o t e local innovations by making the r e q u i r e d resources available. s u m i n g t h e fundamental discussion l a u n c h e d b y c e p a l fifteen years ago on vertical and horizontal d e v e l o p m e n t ; ( ) m o d e l s of t h e u s e of social time, with p a r t i c u l a r reference to the forms of leisure w h i c h h a v e important energy implications a m o n g t h e u p p e r classes w h o are accustomed to leave t h e city d u r i n g t h e w e e k e n d s and s p e n d t h e i r vacations abroad. t h e s e s t u d i e s m a y simultaneously serve as an introduction to t h e discussion on alterna- tives a n d to d e v i s e experiments on a natural scale d e s i g n e d to test the technical and ecolog- ical efficiency of alternative energy systems, t h e social, economic and ecological efficiency of alternative d e v e l o p m e n t strategies with m o d e r a t e e n e r g y r e q u i r e m e n t s , and the opera- tional efficiency of decentralized institutional d e c i s i o n - m a k i n g models supported b y t h e se- l e c t i v e intervention of t h e central authority. i l l conclusion: notes towards a programme development strategies with moderate energy requirements / ignacy sachs t h e p r o g r a m m e sketched out here is ambi- t i o u s , b u t t h e starting point already exists in the s e m i n a r s organized in by c e p a l and the o t h e r u n i t e d nations regional commissions, in collaboration with u n e p , on t h e subject of d e - v e l o p m e n t styles a n d alternative models of re- s o u r c e u s e . it is now a question of pursuing the s a m e line of study, concentrating on the rela- tion b e t w e e n d e v e l o p m e n t and its energy as- p e c t s a n d evaluating the solutions envisaged from t h e standpoint of social appropriateness, e c o n o m i c viability and ecological sustainabili- ty. this may be the author’s version of a work that was submitted/accepted for publication in the following source: motta, nunzio ( ) nanostructures for sensors, electronics, energy and environment [edito- rial]. beilstein journal of nanotechnology, , pp. - . this file was downloaded from: https://eprints.qut.edu.au/ / c© consult author(s) regarding copyright matters this work is covered by copyright. unless the document is being made available under a creative commons licence, you must assume that re-use is limited to personal use and that permission from the copyright owner must be obtained for all other uses. if the docu- ment is available under a creative commons license (or other specified license) then refer to the licence for details of permitted re-use. it is a condition of access that users recog- nise and abide by the legal requirements associated with these rights. if you believe that this work infringes copyright please provide details by email to qut.copyright@qut.edu.au notice: please note that this document may not be the version of record (i.e. published version) of the work. author manuscript versions (as sub- mitted for peer review or as accepted for publication after peer review) can be identified by an absence of publisher branding and/or typeset appear- ance. if there is any doubt, please refer to the published source. https://doi.org/ . /bjnano. . https://eprints.qut.edu.au/view/person/motta,_nunzio.html https://eprints.qut.edu.au/ / https://doi.org/ . /bjnano. . nanostructures for sensors, electronics, energy and environment nunzio motta editorial open access address: school of chemistry, physics & mechanical engineering, queensland university of technology, brisbane, , australia email: nunzio motta - n.motta@qut.edu.au beilstein j. nanotechnol. , , – . doi: . /bjnano. . received: april accepted: april published: may this article is part of the thematic series "nanostructures for sensors, electronics, energy and environment". editor-in-chief: t. schimmel © motta; licensee beilstein-institut. license and terms: see end of document. the areas of nanoscale science and technology are rapidly emerging, with a focus on the design, fabrication, and character- ization of functional objects on the scale of several nanometers. the implications of the new advances in this field are expected to reach far and wide, spanning a variety of scientific and engi- neering disciplines. nanoscale science is growing evermore important on a global scale and is widely seen as playing an integral part in the growth of future world economies. we are all committed to leaving behind a better world for future generations, and nanotechnology can definitely help to improve our environment in several ways. the daunting energy crisis we are facing could be solved not only by new and improved ways of getting energy directly from the sun, but also by saving power thanks to advancements in electronics and sensors. new, cheap dye-sensitized and polymer solar cells hold the promise of environmentally friendly and simple production methods, along with mechanical flexibility and low weight, matching the conditions for a widespread deployment of this technology. their often-criticized scarce efficiency is rapidly growing, thanks to the discovery of new dyes and polymers, which are the fruit of teamwork between chemists, physicists and engineers, all working at the nanoscale. cheap sensors based on nanomaterials can make a fundamental contribution to the reduction of greenhouse gas emissions, allowing the creation of large sensor networks to monitor coun- tries and cities, improving our quality of life. nanowires and nano-platelets of metal oxides are at the forefront of the research to improve sensitivity and reduce the power consump- tion in gas sensors. nanoelectronics is the next step in the electronic roadmap, with many devices currently in production already containing components smaller than nm. molecules [ , ] and conduct- ing polymers [ ] are at the forefront of this research with the goal of reducing component size through the use of cheap and environmentally friendly production methods. this, and the coming steps that will eventually bring the individual circuit element close to the ultimate limit of the atomic level, are expected to deliver better devices with reduced power consump- http://www.beilstein-journals.org/bjnano/about/openaccess.htm mailto:n.motta@qut.edu.au http://dx.doi.org/ . % fbjnano. . beilstein j. nanotechnol. , , – . tion. in this respect the present thematic series is an interest- ing follow-up to the series “transport through molecular junc- tions” published in the beilstein journal of nanotechnology in [ ]. many of these advances have been possible thanks to the discovery of new aggregation forms of materials at the nanoscale, such as fullerenes, nanotubes, graphene [ ] and other carbon structures, or new organic–inorganic mixtures with unexpected properties, discussed also in the series “organic–inorganic nanosystems” edited by paul ziemann [ ]. last but not least, we need to acknowledge that the ability to study these incredible aggregation forms of materials with atomic resolution is mainly due to the developments in scan- ning probe microscopy [ , ] that have occurred over the last years. the beilstein journal of nanotechnology recently hosted the series “scanning probe microscopy and related methods” edited by ernst meyer [ ] and “noncontact atomic force microscopy” edited by udo schwarz [ ] to which the interested reader is directed for more information. science always holds surprises, and i am delighted to present this thematic series, giving a quick glance at the science and application of nanostructures. nunzio motta brisbane, april references . van ruitenbeek, j. m. beilstein j. nanotechnol. , , – . doi: . /bjnano. . . glatzel, t.; zimmerli, l.; kawai, s.; meyer, e.; fendt, l.-a.; diederich, f. beilstein j. nanotechnol. , , – . doi: . /bjnano. . . mena-osteritz, e.; urdanpilleta, m.; el-hosseiny, e.; koslowski, b.; ziemann, p.; bäuerle, p. beilstein j. nanotechnol. , , – . doi: . /bjnano. . . held, c.; seyller, t.; bennewitz, r. beilstein j. nanotechnol. , , – . doi: . /bjnano. . . ziemann, p. beilstein j. nanotechnol. , , – . doi: . /bjnano. . . meyer, e. beilstein j. nanotechnol. , , – . doi: . /bjnano. . . schwarz, u. d. beilstein j. nanotechnol. , , – . doi: . /bjnano. . license and terms this is an open access article under the terms of the creative commons attribution license (http://creativecommons.org/licenses/by/ . ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. the license is subject to the beilstein journal of nanotechnology terms and conditions: (http://www.beilstein-journals.org/bjnano) the definitive version of this article is the electronic one which can be found at: doi: . /bjnano. . http://dx.doi.org/ . % fbjnano. . http://dx.doi.org/ . % fbjnano. . http://dx.doi.org/ . % fbjnano. . http://dx.doi.org/ . % fbjnano. . http://dx.doi.org/ . % fbjnano. . http://dx.doi.org/ . % fbjnano. . http://dx.doi.org/ . % fbjnano. . http://creativecommons.org/licenses/by/ . http://www.beilstein-journals.org/bjnano http://dx.doi.org/ . % fbjnano. . 	references moving towards total cabin filtration: filtering the fresh air supply moving towards complete cabin air filtration filtering the fresh air supply david stein gcaqe aircraft cabin air conference september this presentation is the confidential work product of pall aerospace. no portion of this presentation may be copied, published, performed, or redistributed without the express written authority of a pall corporation officer. the technical data incorporated in this presentation is subject to the export control laws of the united states, in particular, the export administration regulations, eccn e . technical data may not be transferred or otherwise disposed of, either in its original form or after being incorporated into other data, in any way inconsistent with u.s. export control laws. © pall corporation disclaimer our customers guide us our innovative spirit drives us history of innovation energy crisis and fuel economy drive recirculated air systems s pall introduces filters to protect recirculation fans health concerns – microbial loading in recirculated air airlines seek solution ’s pall uses expertise in medical filters to develop hepa rated cabin air filters hepa also reduced haze from cigarette smoking ’s pall validates new filters for full microbial protection in smoking bans highlight supply air and cabin odors issues, increasing the adoption of voc-removing recirculation filters with each generation of filter, we raise the cabin air quality bar. leading airlines now requesting that pall develops fresh air filtration systems to maximize cabin air quality. + maintaining the path of continuous improvement industry and airlines working together for continuous improvement in passenger and crew comfort. easa report march faa website fume events occasionally occur and contaminants can be present in the fresh air supply. the results show that the cabin/cockpit air quality is generally of a good quality. last year, about , flights took off around the world every single day. aviation is still one of the safest ways to travel. current status current filtration options particulate • dust • microbial vocs • bleed air • airport pollution • galley/cabin • electrical. ozone standard fit on all aircraft carbon/hepa option increasingly adopted by leading airlines hepa life performance how odor removal technology improves air quality will ü remove non persistent odors and fume from the cabin to times faster than a cabin without a-caf • by calculation and trials on an aircraft; e.g. minute vs. minutes when new ü reduce the number of reported incidents • reduce lingering smells • improve crew confidence in air quality ü demonstrate the airline is taking all available measures to improve air quality will not ✕ stop fume events (it is in the recirculation line only) ✕ will not prevent odors in conjunction with suitable procedures: assessment of adsorbent filter life ! adsorbent filters are not absolute. unlike hepa they do not have a ‘terminal dp’ efficiency and life depend on boiling points of voc’s moving towards complete cabin air filtration concept & collaboration concept / mandatory elements collaboration extensive r&d in adsorbent materials years’ experience in odor removal years’ experience in cbrn protection years’ experience in aerospace engineering § filter all the air delivered to the cabin § retrofit existing systems § must be easily maintainable the support of airlines and oems was and continues to be vital to the success of this initiative. leveraging bespoke, innovative technology § the synthetic carbon matrix has a very low pressure drop and extremely high adsorbent capacity § it is dust free, extremely durable and presents low sensitivity to humidity § incorporates treatment technology to optimise chemisorption § several media were tested for fractional efficiency and pressure drop, analytically and visually § oil mist in the most penetrating particle range § hepa performance not required to achieve required performance proven performance - cockpit filter - boeing cockpit filter § developed by pall to improve the cockpit air quality and reduce associated disruptions § confirmation from the operator (dhl) that the filter has made a significant difference • improved air quality • reduced disruptions • intending to introduce this system on newly acquired aircraft § approved with an easa stc and released with an easa form from concept to prototype § assess space claim § validate accessibility § generate conceptual design concept: § cfd analysis § prototype build § oem input § installation trials § feasibility review feasibility: § performance tests § ground tests § risk reduction § selected as preferred a option prototype and product: airline support § risk reduction § dfmea § opportunities for key measurements § test fits § ground runs § championing with oem § flight trials § timed filter returns for analysis of actual conditions product realization finally - true cabin air filtration! § ground test for mave q § ready to install on your a aircraft late thank you! any questions? pall aerospace because of technological developments related to the products, systems and/or services described herein, the data and procedures are subject to change without notice. please consult your pall representative or visit www.pall.com to verify that this information remains valid. pall corporation has offices and plants throughout the world. for pall representatives in your area, please visit our website. © copyright . pall corporation, pall and are trademarks of pall corporation. ® indicates a trademark registered in the usa. better lives. better planet and filtration. separation. solution.sm are service marks of pall corporation. thank you visit: www.aerospace.pall.com us: ridge road new port richey, fl telephone + toll free us + uk: portsmouth telephone + ( ) dec-- - .qxd vol. , no. , december child mortality in pakistan is a major cause of concern, the grim picture of the deteriorating child health situation can be seen from annual health report of pakistan medical association (pma) for year , said that, one child dies every minute from diarrhoeal and acute respiratory infection (ari) with annual , infants deaths and one in children die before reaching the age of five. child health in pakistan is amongst the most important national issues that need serious attention. the major reasons behind growing diseases in children may be scanty federal and provincial budget on health services, low income per capita, reduced literacy rate near to %, and lack of skilled birth attendants, widespread diseases and non-existent emergency child health services in government run district and rural hospitals as well as in private hospitals. despite a substantial growth in the number of health institutions, facilities and services, the desired health outcomes of the country could not be achieved due to rapid growth of population and low health budget. the increasing burden of diseases especially, the paediatric diseases represents an iceberg of disease spectrum in our country. the situation is worse if we look at the paediatric emergencies and emergency services around pakistan. basic health units or rural health centers did not have any paediatric emergency settings. tertiary care public sector or private teaching hospitals may have comparatively larger paediatric emergency rooms and are well equipped however the training structure and experience for paediatric emergency physicians are absolutely deficient making the dire need of establishing such a programme in pakistan. paediatric emergency medicine is a newly emerging field in pakistan. it is a medical specialty with the principal mission of evaluating, managing and treating illnesses and injuries in children. paediatric emergency care is the critical component of our health care system posing a huge impact on improving mortality from common childhood illnesses. pakistan, where almost half of the population comprises of children, desperately needs dedicated leadership in pem. the country is already burdened by the sixth largest population in the world (over million people) and one of the fastest growing populations, thus intensifying major challenges like; poverty, illiteracy, energy crisis, terrorism and, indeed, a massive burden of diseases need to be addressed on priority. the resource poor settings of pakistan in which there is limited access to basic emergency care in the major parts of the country put the children at the risk if they acquire any dreadful diseases that pose a threat to their life. to deal with such situations one needs to have appropriate commentary developing paediatric emergency medicine — an opinion from a developing country tertiary care center emaduddin siddiqui, shahan waheed, irum qamar khan department of emergency medicine, aga khan university hospital, karachi. correspondence: emaduddin siddiqui. email: emaduddin.siddiqui@aku.edu figure- : patient flow chart in pem. figure- : pem faculty and fellowship development plan. knowledge and skills, which the physicians must learn in order to diagnose, manage and treat such emergencies. paediatric emergency medicine is established as an evolving specialty around the world and has been practiced in developed countries like usa, canada and uk. it is still in infancy in pakistan. it is an important part of the hospital in most of the developed countries, working in close association with the paediatric icu, in- patient wards, paediatric surgery, paediatric oncology, cardiology and different other specialties in order to provide a laminar flow of the transfer and management of patients who present with different medical or surgical emergencies. this association is not considered a cosmetic or romantic notion but an element that can improve the care of children in our country. it is mentioned in the literature that the delay in managing different paediatric emergencies has resulted in increased mortality and morbidity of the children. there is also an intense need of trained paediatric emergency physicians in dealing with disasters that we have experienced in the past few years. the children are different entity who have different physiological, anatomical and psychological characteristics making them a special population requiring special consideration. the toxicological issues are also very specific in children with our experience of seeing children presenting with a history of putting different household items in their mouth posing an immediate threat to life if not dealt by an appropriate trained person. the paediatric emergency physician must be considered a center of the prong in the continuity of care from outside of the hospital to the in- hospital, in order to provide a friction free care. the need of such a programme in pakistan is because of the increasing burden of respiratory, cardiovascular and gastrointestinal diseases. there are very few centers in the country that have neonatal icu, paediatric icu and other sub-specialties. even paediatric emergency fast track clinics and paediatric triage are considered as another source to deal and managing non-acute paediatric emergencies conserving the precious time of management. similarly paediatric fractures/dislocations, procedures and laceration repair can be managed early with the introduction of the procedural sedation and preventing the resource and time and hence are able to discharge the child home j pak med assoc e. siddiqui, s. waheed, i. q. khan table- : quarterly triage category. (pem, aku data ) total pem visits triage category p triage category p triage category p triage category p triage category p total patients q , , q , , q , , q , , total triage category is based on esi v . edition . table- : patients seen in pem. indicator q q q q total pem visits discharge admitted expired doa los in ed : : : : : referred out lama lwbs * doa; death on arrival los: length of stay in pem lama: left against medical advice lwsb: left without been seen * patients were those who were lwsb by the pem physician retrieved form aku intranet sahl and adt (admission, discharge and transfer data, dated: july , . vol. , no. , december developing paediatric emergency medicine — an opinion from a developing country tertiary care center early and reduce emergency congestion. there is a dire need to develop paediatric emergency medicine in pakistan by promoting structure training to our doctors. this sub-specialty has a pivotal role in the society and medical community and is essential for all secondary and tertiary care hospitals both government and private, in order to provide timely and perfect care for our children. it is still a long way to follow for a better childcare, research, innovation, practice and learning. the aga khan university has an established pem (table- and ), and the need for this specialty is endorsed by the experience gained in this department. this has encouraged us to propose a fellowship programme in this sub-specialty in the institution and at a national level (figure- and ). references . baker t. paediatric emergency and critical care in low-income countries. paediatr anaesth ; : - . . siddiqui eu, razzak ja. paediatric emergency medicine--an evolving subspeciality in pakistan. j coll physicians surg pak ; : - . . siddiqui eu, ejaz k. strengthening paediatric emergency medicine in pakistan is our need to reach millennium development goal . j pak med assoc ; : - . american college of emergency physicians. a decade of advancements in paediatric emergency care. [online] [cited jun ). available from url: http://www.acep.org/webportal/ patientsconsumers/healthsubjectsbytopic/pediatrics/fact sheet a decadeofadvancementsinpediatricemergencycare.htm. . walker md, tolentino rv, teach js. trends and challenges in international paediatric emergency medicine. curr opin pediatr ; : - . . chalfin db , trzeciak s, likourezos a, baumann bm, dellinger rp; delay-ed study group. impact of delayed transfer of critically ill patients from the emergency department to the intensive care unit. crit care med ; : - . . guidelines for pediatric emergency care facilities. american academy of pediatrics committee on pediatric emergency medicine. pediatrics ; : - . . chande vt, krug se. practitioners of pediatric emergency medicine: a -year longitudinal study. pediatr emerg care ; : - . . rowe bh, channan p, bullard m, blitz s, saunders ld, rosychuk rj, etal. characteristics of patients who leave emergency departments without being seen. acad emerg med , : - . . couloures kg, beach m, cravero jp, monroe kk, hertzog jh. impact of provider specialty on pediatric procedural sedation complication rates. pediatrics ; : e - . . gilboy n, tanabe p, travers d, rosenau am. emergency severity index (esi) a triage tool for emergency department care. version , edition . [online] [cited sep ]. available from: url: http://www.ahrq.gov/professionals/systems/hospital/esi/esihand bk.pdf. a physicist out of academia a physicist out of academia james t. dakin citation: physics today , , ( ); doi: . /pt. . view online: https://doi.org/ . /pt. . view table of contents: https://physicstoday.scitation.org/toc/pto/ / published by the american institute of physics articles you may be interested in an atomic physics perspective on the kilogram’s new definition physics today , ( ); https://doi.org/ . /pt. . murray gell-mann physics today , ( ); https://doi.org/ . /pt. . friend raising for physics physics today , ( ); https://doi.org/ . /pt. . tying celestial mechanics to earth’s ice ages physics today , ( ); https://doi.org/ . /pt. . neckties or not, and a quick fix physics today , ( ); https://doi.org/ . /pt. . nsf and postwar us science physics today , ( ); https://doi.org/ . /pt. . https://physicstoday.scitation.org/action/clickthrough?utm_medium=article download&utm_campaign=mcl_jad_ &loc=pt/pdf&pubid= &placeholderid= &productid= &id= &url=http% a% f% fwww.madcitylabs.com% futm_source% daip% physics% today https://physicstoday.scitation.org/author/dakin% c+james+t /loi/pto https://doi.org/ . /pt. . https://physicstoday.scitation.org/toc/pto/ / https://physicstoday.scitation.org/publisher/ https://physicstoday.scitation.org/doi/ . /pt. . https://doi.org/ . /pt. . https://physicstoday.scitation.org/doi/ . /pt. . https://doi.org/ . /pt. . https://physicstoday.scitation.org/doi/ . /pt. . https://doi.org/ . /pt. . https://physicstoday.scitation.org/doi/ . /pt. . https://doi.org/ . /pt. . https://physicstoday.scitation.org/doi/ . /pt. . https://doi.org/ . /pt. . https://physicstoday.scitation.org/doi/ . /pt. . https://doi.org/ . /pt. . physics today | may readers’ forum physics department, encapsulates the essence of the scientific method. i know such an ideal is infeasible on so many lev- els, but i believe that the world would be a much better place if everyone, not just every physicist, were to read the book as part of an undergraduate education. we might want to revisit bevington as an exemplar not just of scientific- method education but of meta-instruc- tion in effective pedagogy in general. phil bevington seems to have struck the perfect balance of detail, rigor, practical- ity, and clarity. tom marshall (thomas_marshall@msn.com) new york city neckties or not, and a quick fix i appreciate brian kraus’s review of my book real scientists don’t wear ties: when science meets culture (physics today, march , page ). the photo spread of diverse physicists mostly not wearing ties underlines a point i made in the book: more than ever, we physi- cists look different from each other and dress the way we want to. however, i must correct an error kraus made when he wrote that i retired from academia in . as i stated in my book’s introduc- tion (page xi), i continued academic re- search and teaching until , when i retired as charles howard candler emeritus professor of physics after years at emory university. sidney perkowitz (physp@emory.edu) emory university atlanta, georgia a physicist out of academia t he commentary from elizabeth frank (physics today, october , page ) about her career move from acade- mia to industry resonated with me in many ways . i largely agree with frank’s statement that “you don’t have to justify your motivations to anyone but yourself,” but i also point out that career changes can deeply affect one’s family. as frank mentions, physics professors often have limited awareness of opportu- nities outside academia; therefore, input from someone with a career like mine is important. my path is significantly differ- ent from frank’s, and i speak from later in life. furthermore, the variety of careers available to physicists is much greater outside academia than within. my experiences in academic physics began when i was a precocious elementary school student and grew through wonder- ful experiences at harvard, princeton, and stanford universities to a tenure-track as- sistant professor position at the university of massachusetts amherst. at harvard, i had strong physics courses and valuable interaction with renowned physicists, in- cluding my adviser norman ramsey. at princeton, i completed a phd in experi- mental high-energy physics in less than four years. during my postdoc at stanford in the early s, i had the good fortune to work at slac on two experiments that led to nobel prizes—one for burton richter and one for martin perl. i then took a tenure- track assistant professorship at umass, where i continued the work at slac while helping a local umass team start an experiment at brookhaven national lab- oratory. all was going well. nonetheless, at age i had a midlife crisis and decided to move from academia to industry. to frank’s point, the switch was deeply personal. at least three factors contributed to my malaise. first, i felt locked into my high-energy-physics spe- cialty and was concerned about its future. the significant projects were getting much bigger, taking much longer, based in more distant laboratories, and produc- ing increasingly arcane results. it seemed harder all the time for me to continue to derive personal satisfaction from the field. a second factor was that as an exper- imenter, i felt that i should understand the theories pertaining to my experi- ments, but they had reached a level of ab- straction beyond my comprehension. third, i was concerned about the s energy crisis associated with the arab oil embargo, and i wanted to help address it. i landed a job at the ge research and development center in schenectady, new york. my wife was shocked but supportive: our two children were young and portable, and her career actu- ally benefited from the move. my experiences in industry during years with ge were also wonderful, but in different ways from my time in aca- demic high-energy physics. my work at ge was mostly in lighting technology. after a decade i moved to the headquar- ters campus of ge lighting in cleveland, ohio. i have done research that has been published in refereed journals. it has al- ways been on problems with near-term, real-world significance. i have also worked on developing and producing new energy-saving lighting products. every few years my role morphed as the business changed and new needs arose. those changes were invigorating as i gained new insights. i often started new assignments with little of the requi- site technical know-how, but i was a quick learner with a background in basic physics and wonderful, talented, and technically diverse coworkers. the busi- ness funded the work, with no external grant proposals needed. i have had plenty of opportunity to teach, and i have enjoyed it. toward the end of my career at ge, i was involved in the led technology revolution. since retiring, i have developed a successful consulting business that draws heavily on technical knowledge of light sources. i look back to my decision at age as the most important one of my career. on the one hand, academia might have pro- vided better opportunity for long-term career focus and development of deep expertise. on the other hand, industry did provide stimulating work with near- term, beneficial, real-world significance. it also offered invigorating career and as- signment changes. i have never regretted my decision, but i will never know where the path not taken might have led. james t. dakin (jim_dakin@yahoo.com) shaker heights, ohio pt letters and commentary are encouraged and should be sent by email to ptletters@aip.org (using your surname as the subject line), or by standard mail to letters, physics today, american center for physics, one physics ellipse, college park, md - . please include your name, work affiliation, mailing address, email address, and daytime phone number on your letter and attachments. you can also contact us online at https://contact.physicstoday.org. we reserve the right to edit submissions. contact physics today cience american association for the advancement of science science serves its readers as a forum for the presentation and discussion of important issues related to the advance- ment of science, including the presentation of minority or con- flicting points of view, rather than by publishing only material on which a consensus has been reached. accordingly, all ar- ticles published in science-including editorials, news and comment, and book reviews-are signed and reflect the indi- vidual views of the authors and not official points of view adopted by the aaas or the institutions with which the au- thors are affiliated. publisher: philip h. abelson, acting editor: daniel e. koshland, jr. deputy editor: john . brauman (physical sciences) editorial staff managing editor: patricia a. morgan assistant managing editor: nancy j. hartnagel senior editor: eleanore butz associate editors: keith w. 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( - - ); u.k., europe: nick jones, + ( ) ; telex ; fax ( ) . information for contributors appears on page xl of the december issue. editorial correspondence, including requests for permission to reprint and reprint orders, should be sent to h street, nw, washington, dc . tele- phone: - - . advertising correspondence should be sent to tenth floor, broadway, new york, ny . telephone - - or wu telex scherago, or fax - - . january i volume number a tax on sin: the six-cylinder car if taxes are inevitable we might as well have those that serve the national need and are popular at the same time. for this purpose, taxes on sin seem to be the only sensible choice. there are two types of sin: those committed by other people and those committed by oneself. taxes on the sins of others will of course have wide approval; taxing the wicked is exactly what the internal revenue service should be expected to do. on the other hand, taxing one's own sin is a violation of civil liberties and an outrageous intrusion on the inalienable right to the pursuit ofhappiness. such taxes, however, have some positive aspects. it is somewhat like going to a charity ball at which conspicuous consumption can be rationalized on the basis that the money spent is not for one's personal pleasure, but rather a contribution to the helpless and the homeless who are the recipients of the charity. it allows one to indulge and expiate one's sins at the same time, while also acquiring something of a reputation as a bon vivant. nothing is as deadly to one's reputation as being considered totally virtuous. because most people like to be classed as charming scalawags, the federal government might as well benefit from the urge to sin. once the decision to tax has been made, the next step is to identify those sins that can be taxed to serve the national interest. one that seems obvious is owning a car that gets less than miles per gallon of gasoline. science and technology are steadily improving the efficiency of automobiles so that cars averaging miles per gallon can be readily obtained with a slight sacrifice of comfort, and those giving miles per gallon with a little more discomfort. to a large extent the improvement in efficiency and conservation resulting from small cars has helped break the opec cartel and avert another energy crisis. has the united states proceeded intelligently to improve and expand this conservation program? of course not. energy efficiency and low gasoline prices have resulted in a return to heavier cars together with government encouragement of this sin by backsliding on the mileage-per- gallon goals given to the automobile industry. because most driving occurs with a single passenger in the car, a big car is energy-inefficient and adds to the co problem, the acid rain problem, and the no, pollution problem. today about a third of the u.s. trade deficit results from the importation offoreign oil. thus, a tax that would maintain an appropriate cost ofgasoline and one on cars ofhigh horsepower would decrease fuel consumption, make a contribution to environmental problems, provide added revenue for child care, care of the chronically ill and other worthy enterprises, and improve our balance of payments. such a tax could be designed to be neither regressive nor coercive. if cleverly designed, and introduced over a period ofyears, it would not increase the cost oftransportation for the average person because efficiency would be balanced against cost. it would not be coercive because the laws could specify that any individual would have the right to buy a heavy, mileage-inefficient car, but such a car would have an appropriately heavy "sin tax," so that the buyer would pay for the luxury. any individual purchasing such a large and extravagant car would, of course, be considered sinful, but a sort of robin hood type of sinner, of whom the gossips could say, "there goes old joe, can't resist the temptation ofa gas guzzler, but on the other hand, he's supporting one widow, two orphans, and three toxic waste dumps." since this type of sin would be expensive, only those who were excessively virtuous in other areas would feel the necessity of establishing themselves as sinners in this new category. if phased in properly, the main sacrifice would be in comfort, and it is widely understood that loss of comfort is almost synonymous with virtue. once this kinder, gentler approach to sin and taxes became widely accepted, the sin tax could be extended to other areas in a similar approach to produce a national policy. in the past, sin has been almost universally identified with personal preference. sanctimonious and humorless attacks on smokers, drinkers, philanderers, and other offenders have had a polarizing effect, either making the one attacked look like a criminal or the attacker look like an inquisitor. a system of pay-as-you-go sin, in which sin is defined on the basis of national policy rather than personal peccadillo, could put self-indulgence in the service of the national good.-daniel e. koshland, jr. january i editoria-l i o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ a tax on sin: the six-cylinder car daniel e. koshland jr. doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the is a registered trademark of aaas.sciencescience, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for the advancement ofscience by the american association for the advancement of science. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ human energy suzana sawyer published online: august � the author(s) . this article is published with open access at springerlink.com abstract in the midst of big-oil record profits and growing debate on global warming, the chevron corporation launched its ‘‘human energy’’ public relations campaign. in television commercials and print advertisements, chevron portrays itself as a compassionate entity striving to solve the planet’s energy crisis. yet, the first term in this corporate oxymoron misleadingly reframes the significance of the second, suggesting that the corporation has a renewed focus. in depicting chevron as a green/human organization, the ‘‘human energy’’ campaign obscures from view the corporation’s more unsightly products, policies, and practices. reflection, however, on our own complicity in sustaining energy corporations and their activities undermines binary thinking and signals that the compulsion to denounce is insufficient. this article explores chevron’s media campaign and one organized reaction to it. this counter-campaign both redeployed chevron’s imagery and underscored our collusion and responsibility—tactics seeking to loosen the taut inevitability-of-oil story at chevron’s core. keywords chevron � ecuador � oil � politics of denunciation � politics of implication � public relations � corporate oxymoron across a blackened screen appear the words ‘‘tapped energy.’’ soon they morph into ‘‘untapped energy.’’ the words fill the mind, rhythmically pulsating through a compelling score. the visual images are raw, direct, open. a two-minute television commercial by the chevron corporation has just begun. experience the power of ‘‘human energy’’: s. sawyer (&) university of california, davis, ca, usa e-mail: smsawyer@ucdavis.edu dialect anthropol ( ) : – doi . /s - - - and outside, the debate rages. oil. energy. the environment. it is the story of our time, and it is definitive and all encompassing. and it leaves no one untouched. because make no mistake, this isn’t just about oil companies, this is about you and me. and the undeniable truth that at this moment there are . billion people on this planet, and by year’s end there will be another million. and every one of us will need energy to live. where will it come from? this is chevron’s challenge each day. because for today and tomorrow and the foreseeable future, our lives demand oil. but what’s also true is that we can provide it more intelligently, more efficiently, more respectfully, that we’ll never stop looking for alternatives, that an oil company can practice and espouse conservation. yes, we are an oil company, but right now we are also providing natural gas, solar, hydrogen, geothermal. because we live on this planet too. this is who we are, in countries. not corporate titans. but men and women of vision. fifty-eight-thousand citizens of the world. liberals and conservatives. engineers and scientists. pipeline welders and geologists. husbands and wives. part-time poets and coaches. peoples who daily try to find newer ways, cleaners ways, to power the world. humans have always reached for what seemed impossible. because it is then that we find a way. tell us it can’t be done. then watch as we tap the greatest source of energy in the world—ourselves. against a white backdrop, the word ‘‘oil’’ quickly morphs into ‘‘geo-thermal’’ then ‘‘solar,’’ ‘‘natural gas,’’ ‘‘hydrogen,’’ ‘‘conservation,’’ and finally ‘‘chevron.’’ the narrator’s voice returns: ‘‘this is the power of human energy.’’ in september , in the midst of record-breaking profits and a growing global debate on energy consumption, and global warming, the chevron corporation launched its ‘‘human energy’’ campaign. through a multi-million dollar publicity campaign, chevron—a globally integrated energy company whose business encompasses every facet of the petroleum and natural gas industries—presents itself as a caring entity striving to solve the world’s energy crises through the power of human creative forces. chevron is the second largest oil company in the united states, and the fourth largest in the world—trumped only by exxon, shell, and bp. what does it mean when a petroleum corporation personifies and humanizes itself as working in the service of humanity (‘‘this is who we are. not corporate titans. but men and women of vision’’)? what sorts of distinctions are made and unmade when a corporation takes on and subtly reframes the questions of its critics (‘‘oil, energy, the environment. it is the story of our time’’)? how are geographies of inequality, risk, and accountability transformed through emotive cinematography and narrative that situate the energy crisis at the global level (‘‘and the undeniable truth that at this moment there are . billion people on this planet…. and every one of us will need energy to live.’’)—and its solution in the individual (‘‘tell us it can’t be done. then watch as we tap the greatest source of energy in the world—ourselves’’)? chevron’s ‘‘human energy’’ campaign consists of a number of tv commercials and print advertisements showcased in magazines and on billboards across the u.s. and beyond. in this essay, i reflect on this public relations makeover, focusing on the s. sawyer television spot (first aired during ‘‘ minutes’’ on september , ), print advertisements, and one dimension of the organized reaction to chevron’s media campaign. shot in locations in countries over a -months period, ‘‘untapped energy’’ reflects a polish and emotion rarely captured by an oil company. a new york advertising agency, mcgarrybowen, produced the effect, using the cinematography of lance acord (of ‘‘lost in translation’’ and ‘‘being john malkovich’’ fame), the musical score of paul leonard-morgan (a young uk composer), and the voice of campbell scott (an acclaimed indie actor). with its rough sleekness, its documentary grit and grip, ‘‘untapped energy’’ has more the feel of a rallying cry of compassion than a market-oriented advertisement by a beneficiary of economic liberalization. human energy like the orwellian newspeak that peter benson and stuart kirsch discuss in the introduction to this forum, the first term reframes the significance of the second, lending the corporation a renewed focus. ‘‘human energy’’—the embodied ingenuity inherent in every individual—not hydrocarbon fuel, we are asked to recognize, is really at the core of chevron’s business. yet, in framing the corporation as a human organization determined to work for our planet, the ‘‘human energy’’ campaign fades out lived realities and abiding revenue streams that the corporation would prefer its viewers not see. a cluster of ngos concerned with climate change and environmental responsibility has roundly debunked the ‘‘human energy’’ ads as a case of ‘‘greenwashing.’’ to that we might add ‘‘fleshwashing’’— that is, by showcasing environmental and humanistic commitment the commercials seek to conceal the corporation’s more unsightly products, policies, and practices. no doubt many lovely people work for chevron—be they part-time poets or coaches. human energy is an important part of what makes the company tick. however, the vast majority of chevron’s employees do not make corporate decisions. a handful of directors and executive managers do and are bound by their fiduciary responsibility to shareholders. and while many individuals within the corporation may be earnestly committed to resolving our future energy dilemmas, chevron has obscured from view the fact that many others around the world find it woefully incapable of doing just that. their experience stands as a gnawing reminder of how unkind the corporation’s activities have been socially, econom- ically, and environmentally. in , a class action lawsuit, bowoto v. chevron, in the san francisco district court alleged that chevron had violated human rights and destroyed natural ecosystems in nigeria’s niger delta region. in early december , a jury exonerated chevron of all claims. however, the decision—surely to be appealed— arguably exposed the difficulty of suing a transnational entity in the u.s. for abuses overseas as much as it offered a pronouncement on chevron’s practices. another lawsuit, aguinda v. chevron, is currently underway in an ecuadorian superior court where chevron is being sued; texaco inc., which it bought in , is alleged to have knowingly contaminated the environment and endangered the health of peoples in the northern ecuadorian amazon. opposing parties expect the ecuadorian judge to rule on the case by the end of , years after it was first filed in the new york federal court. the practices that these (and other) human energy litigations seek to condemn are not isolated, but part and parcel of how many oil operations have been carried out around the world. although it is unlikely that chevron’s advertisements will significantly change individual views of big oil, the campaign does have the possibility of shifting the debate. juxtaposing environmental concerns (‘‘and outside, the debate rages. oil. energy. the environment. it is the story of our time’’) with the more immediate ‘‘undeniable truths’’ of population explosions and its accompanying demand for more energy, the chevron ads make clear that renewable sources, while complementary, are not a panacea: ‘‘because for today and tomorrow and the foreseeable future, our lives demand oil.’’ hydrocarbon fuels are both necessary and inevitable. end of discussion. well, almost. for, ‘‘what is also true is that we can provide [oil] more intelligently, more efficiently, more respectfully… that an oil company can practice and espouse conservation.’’ both green and flesh edge their way back onto the legitimacy score-board. at stake is not simply the possibility of winning over more consumers through the banding of chevron petroleum products as environmentally and socially friendly. i suspect the majority of consumers buy their gasoline where they deem most convenient, weighing time, traffic, and cost concerns. rather, the way chevron positions the issues and promotes a reasonable solution eases the mind of consumers. and this embellishes—as robert foster ( ) reminds us—that more intangible commodity that chevron seeks to sell: its stock. however, unaccounted for in the ‘‘human energy’’ campaign is the harm caused not only in getting, but also in burning, chevron’s fossil fuels. much like the cigarette that peter benson analyzes, hydrocarbons ‘‘injure’’ as a matter of course when consumed as intended. yet, something more is going on with the ‘‘untapped energy’’ commercial. it evokes a logic of sensation that exceeds its story. gilles deleuze ( ) suggests that sensations that hit the body, directly affecting the neurological system without passing through the analytics of the brain, both reverberate sentiments of dominant forms and open up possibilities for things to be otherwise—for different sensibilities of the world to catch hold. they flood in instants of enactment and composition, and may, as with chevron’s television commercials, be the effect of highly scripted choreography to evoke a blush of caring, commitment, and exhilaration. yet, they also invoke senses of rhizomatic entanglements, of sentient participation and unwitting support that blur clear divisions (i.e., good guys/bad guys) by surfacing questions of involvement and responsibility. chevron is right: at this moment, at this time, at this particular historical conjuncture, we in the over-consuming hyper- spaces of an ever-precarious modernity do depend on the extraction of hydrocarbons to fuel our world. complicity invites reflection. it also suggests that the compulsion to denounce, rather than inspect the relationships we sustain with and through chevron and oil more generally, is insufficient. on may , , the day of chevron’s annual general meeting (agm), hundreds of people gathered in front of chevron’s headquarters in san ramon, california, to denounce a number of the corporation’s practices. the protest encompassed two wider forms of engagement: an initiative to subvert chevron’s human energy campaign and an initiative to embrace the position of stockholders. s. sawyer the first strategy redeployed the print advertisement component of chevron’s human energy campaign which similarly seeks to trigger a logic of sensation that invokes a blush of caring, commitment, and integrity. appearing in magazines and on billboards, these ads depict close-up face shot of diverse, thoughtful individuals with a personalized commitment chalked across their image: ‘‘i will use less energy’’; ‘‘i will leave the car at home more’’; ‘‘i will turn stuff off more.’’ beside them is small print-copy of chevron’s commitment to do the same: ‘‘and we will too. the world demands more and more energy. where will it come from? we at chevron are working to provide more of it, both responsibly and efficiently….’’ (figs. and ). in response to these ads, in the spring , members of amazon watch—a california-based environmental and indigenous rights group—spearheaded an ‘‘inhumane energy’’ campaign. deploying what activists call ‘‘subvertisement,’’ the campaign decries chevvrong [sic] and its practices around the globe, especially in ecuador where amazon watch has sustained a multifaceted and critical effort in support of the plaintiffs suing chevron for alleged environmental contamination and its effects. against the backdrop of similar kind and earnest portraits, chalky script proclaims: ‘‘i will try not to have a miscarriage’’; ‘‘i will ignore the toxic waste pits in my village’’; ‘‘i will try not to get cancer.’’ along side the faces is print-copy that reads: ‘‘chevron’s toxic dumping in ecuador causes miscarriages, birth defects and cancer’’ or ‘‘chevron dumped over billion gallons of toxic waste into the amazon. learn more at truecostofchevron.com’’ (figs. and ). outside chevron’s gated headquarters, these and other subvertisements filled the lawn as a coalition of protesters greeted early morning shareholders arriving to fig. ‘‘i will use less energy.’’ one of chevron’s human energy print advertisements (http://www. chevron.com/about/advertising/#b ) human energy http://www.chevron.com/about/advertising/#b http://www.chevron.com/about/advertising/#b fig. ‘‘i will leave the car at home more.’’ another human energy print advertisements (http://www. chevron.com/about/advertising/#b ) fig. ‘‘i will ignore the toxic waste pits in my village.’’ one of amazon watch/true cost of chevron coalition’s inhumane energy ‘‘subvertisements’’ (http://truecostofchevron.com/ecuador.html) s. sawyer http://www.chevron.com/about/advertising/#b http://www.chevron.com/about/advertising/#b http://truecostofchevron.com/ecuador.html attend the corporation’s agm. a billboard picturing the smiling face of chevron’s ceo, bill o’reilly, read, ‘‘i will pretend to care about the environment’’ against thick smoke billowing from a refinery. another depicted a portrait by lou dematteis of a man in his early s dying from cancer in the ecuadorian amazon. superimposed on the image is the ticker tape of stock prices and net change: cvx $ . m ? %; luis $ . . - %. and scattered across the entrance lawn were people holding framed posters of clear plexiglas through which their faces appear behind the chalked commitment: ‘‘i will expose toxic polluting’’; ‘‘i will expose over profiteering’’; i will expose climate destruction’’; i will expose greenwashing’’ (figs. and ). inside the stockholders’ annual meeting, the founder of amazon watch, attosa soltani, together with individuals representing financial institutions, pension funds, and environmental and human rights organizations, confronted chevron’s ceo with questions raised in their jointly proposed shareholder resolution. detailing in its preamble concern over chevron’s practices in ecuador, nigeria, and burma, the resolution requests that the board prepare a report ‘‘on the policies and procedures that guide chevron’s assessment of host country laws and regulations with respect to their adequacy to protect human health, the environment and our company’s reputation.’’ now in its fifth year, this shareholder resolution reflects what some fig. ‘‘i will try not to have a miscarriage.’’ another inhumane energy ‘‘subvertisements’’ (http://true costofchevron.com/ecuadors.html) item on the proxy card submitted to the u.s. securities and exchange commission and with shareholders in advance of the annual general meeting on april , . human energy http://truecostofchevron.com/ecuadors.html http://truecostofchevron.com/ecuadors.html fig. protestors redeploying the chevron ‘‘human energy’’ print ads outside the corporation’s agm, photo by suzana sawyer fig. more protestors outside chevron’s agm, photo by mike kepka s. sawyer call ‘‘share power’’—a tactic that emerges from and engenders reflection on the entangled links through which we sustain and condone multinational corporations and their activities. invoking proximity, convergence, and confrontation as tools that the corporate form legally grants them, shareholder activists seek to use the power of shares and their voice as investors to transform corporate activity. they seek to question specific corporate practices, to inform stockholders of their concerns, and challenge a corporate structure in which ‘‘owners’’ are largely passive to ‘‘managers.’’ theirs is a strategy of surfacing openings that emerge from involvement, tacit collusion, and responsibility. invoking forms of implication might muddle ‘‘the seductive clarity of denun- ciation’’ (redfield , p. ), but it also allows for various attachments to a denunciatory stance—potentially compelling subversive relays in unanticipated ways. a web of affective registers exceeds chevron’s story, tantalizing with the promise that the confines of comfortable compromise—e.g., the inevitability of oil—might loosen. this is the immanence of possibility captured through engaging in entanglements. this is the power of human energy that chevron never bargained for. open access this article is distributed under the terms of the creative commons attribution noncommercial license which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. references deleuze, gilles. . francis bacon: the logic of sensation. minneapolis: university of minnesota press. foster, robert j. . the work of the ‘‘new economy’’: consumers, brands and value. cultural anthropology ( ): – . redfield, peter. . doctors, borders, and life in crisis. cultural anthropology ( ): . human energy 	human energy 	abstract 	open access 	references << /ascii encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (none) /calrgbprofile (srgb iec - . ) /calcmykprofile (iso coated v % \ eci\ ) /srgbprofile (srgb iec - . ) /cannotembedfontpolicy /error /compatibilitylevel . /compressobjects /off /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /perceptual /detectblends true 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/pdfxtrimboxtomediaboxoffset [ . . . . ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ . . . . ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org?) /pdfxtrapped /false /description << /deu <feff a f f f e f f c c e d f c f f e c e e d e d c d d d c f e e f e c f a f f f f e e e e f d d f e c f e c e f f c f f f f e c e f f c e f c f a f d f e e> /enu <feff a f f f e f f c c e d f c f c e e e f e c e e d e e d d > >> >> setdistillerparams << /hwresolution [ ] /pagesize [ . . ] >> setpagedevice september , volume , number american association for the advancement of science science serves its readers as a forum for the presentation and discussion of important issues related to the advancement of science, including the presentation of minority or conflicting points of view, rather than by publishing only material on which a consensus has been reached. accord- ingly, all articles published in science-including editorials, news and comnent, and book reviews- are signed and reflect the individual views of the authors and not official points of view adopted by the aaas or the institutions with which the authors are affiliated. editorial board ' alfred brown james f. crow seymour s. kety frank press frank w. putnam maxine f. singer gordon wolman herbert s. gutowsky donald lindsley n. bruce hannay ruth patrick donald kennedy raymond h. thompson daniel e. koshland, jr. editorhl staff editor: philip h. abelson business manager: hans nussbaum managing editor: robert v. ormes assistant editors: ellen e. murphy, john e. ringle assistant to the editors: patricia rowe news and comment: john walsh, lurher j. carter, deborah shapley, robert gillette, nicho- las wade, constance holden, barbara j. culliton, scherraine mack research news: allen l. hammond, william d. metz, thomas h. maugh ii, jean l. marx, arthur l. robinson, gina bari kolata, fannie groom book reviews: katherine livingston, lynn manfield, ann o'brien cover editor: grayce finger editorial assistants: margaret allen, isabella bouldin, eleanore butz, mary dorfman, sylvia eberhart, judith givelber, corrine harris, nancy hartnagel, oliver heatwole, christine karlk, margaret lloyd, eric poggenpohl, jean rockwood, leah ryan, lois schmrrr. richard semiklose ya li swigart, eleanor warner guide to scientific instruments: richard sommer membership recruitment: gwendolyn huddle; subscription records and member records: ann ragland advertising staff director production manager earl j. scherago margaret sterling advertising sales manager: richard l. charles sales: new york, n.y. : herbert l. burklund, w. st. 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( - - ) editorial correspondence: massa- chusetts ave., nw, washington, d.c. .. phones: (area code ) central office: - ; book re- views: ; business office: - ; circula- tion: - ; guide to scientific instruments: - ; news and comment: - ; reprints and permissions: - ; research news: - ; reviewing: - . cable: advancesci. washington. copies of "instructions for contributors" can be obtained from the editorial office. see also page xv. science, june . advertising corre- spondence: room , w. st., new york, n.y. . phone: -pe- - . sci:ence the humility factor there is a humbling lesson in the recent sharp decline in highway fatalities. traffic accidents are a major social problem by any standard, and until recently more americans died each year on the roads than in all the years of war in southeast asia, roughly , in . the number of persons injured that same year ran to , , . the annual economic loss per seriously injured person in medical expenses, property damage, and lost earnings runs into the billions. over the years the problem was studied and a variety of efforts were launched to correct it. some favored the educational approach, especially driver education classes and public persuasion campaigns ("the life you save may be your own"s). others subscribed to technological cures: redesign of the automobile (ralph nader argued that the cars were "unsafe at any speed," not the drivers) and redesign of the roads (rail- ings, flexible signposts, and so on). still others appealed to the long arm of the law, asking for stiffer penalties for traffic violators and mandatory use of seat belts. and yet another set of people pointed to alcohol as the major cause of fatal accidents and called for greater use of breath analyzers to get those driving while under the influence of liquor off the road. each approach had its proponents, detractors, supportive data, and counterclaims. the number of traffic deaths continued to rise from , in to , in to , in , while injuries went from , , to , , to , , in the same years. then came the energy crisis, hardly designed by any traffic safety council, and the mile an hour speed limit, introduced, oddly enough, not to save lives but to conserve energy. since then the slaughter on the highways has been curtailed by more than percent. this is not the only social problem to be drastically affected by factors neither foreseen nor deliberately introduced for the purpose. the sharpest drop in the number of mental patients in state mental hospitals was caused not by any root change in the psychiatric treatment ad- ministered, but chiefly by the discovery of tranquilizers, which allow many patients to remain at home with little cost to the state. thanks to tranquilizers, the number of people kept incarcerated in state mental hospitals fell from , in to , in . finally, the problems of the major urban centers, such as housing, welfare, and busing, were to a very large degree created by an influx of millions of poor americans from the countryside, especially the south. more than any program created by any major city council or state or federal agency, the recent cessation and partial reversal of this move- ment, including remigration to the south, may ameliorate conditions in the cities. (between and , . million blacks alone left the south. a recent study suggests that between and more blacks migrated to the south than from the south.) the moral? our capacity to engineer society is at a relatively early and primitive stage. the cliche "if we can put a man on the moon, we should be able to . . ." holds only as an aspiration for the farther future. for the near one, humility is of the essence. a scientific orientation to our societal problems is essential, but first of all in the sense of a rational, open-minded, empirical orientation, rather than one which relies on a priori beliefs and assumptions. the easy optimism that goes with the assumption that we can design a quick cure for most things that ail us is not called for. it results in an oversell of what science and tech- nology can do for the highly intricate, societal world, whose dynamics we are only slowly learning to understand.-amitai etzioni, professor of sociology, columbia university, and director, center for policy re- search, inc., riverside drive, new york o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ the humility factor amitai etzioni doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the trademark of aaas. is a registeredscienceadvancement of science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for thescience by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ /home/www/ftp/data/hep-th/dir_ / .dvi energy crisis or a new soliton in the noncommutative cp( ) model? subir ghosh physics and applied mathematics unit, indian statistical institute, b. t. road, calcutta , india. abstract: the non-commutative (nc) cp( ) model is studied from field theory perspective. our for- malism and definition of the nc cp( ) model differs crucially from the existing one [ ]. due to the u( ) gauge invariance, the seiberg-witten map is used to convert the nc action to an action in terms of ordinary spacetime degrees of freedom and the subsequent theory is studied. the nc effects appear as (nc parameter) θ-dependent interaction terms. the expressions for static energy, obtained from both the symmetric and canonical forms of the energy momentum tensor, are identical, when only spatial noncommutativity is present. bogomolny analysis reveals a lower bound in the energy in an unambiguous way, suggesting the presence of a new soliton. however, the bps equations saturating the bound are not compatible to the full variational equation of motion. this indicates that the definitions of the energy momentum tensor for this particular nc theory, (the nc theory is otherwise consistent and well defined), are inadequate, thus leading to the ”energy crisis”. a collective coordinate analysis corroborates the above observations. it also shows that the above mentioned mismatch between the bps equations and the variational equation of motion is small. keywords: cp( ) model, noncommutative field theory, seiberg-witten map. introduction non-commutative (nc) field theories have turned into a hotbed of research activity af- ter its connection to low energy string physics was elucidated by seiberg and witten [ , ]. specifically, the open string boundaries, attached to d-branes [ ], in the presence of a two-form background field, turns into nc spacetime coordinates [ ]. (this phenomenon has been recov- ered from various alternative viewpoints [ ].) the noncommutativity induces an nc d-brane world volume and hence field theories on the brane become nc field theories. studies in nc field theories have revealed unexpected features, such as uv-ir mixing [ ], soliton solutions in higher dimensional scalar theories [ ], to name a few. the inherent non- locality, (or equivalently the introduction of a length scale by θ - the noncommutativity param- eter), of the nc field theory is manifested through these peculiar properties, which are absent in the corresponding ordinary spacetime theories. also, solitons in nc cp( ) model have been found [ ], very much in analogy to their counterpart in ordinary spacetime. the present work also deals with the search for the solitons in the nc cp( ) model. the difference between our field theoretic analysis and the existing framework [ ] is explained below. in fact, we closely follow the conventional field theoretic approach in ordinary spacetime [ ]. the seiberg-witten map [ ] plays a pivotal role in our scheme. the bogolmolny analysis of the static energy reveals a lower bound, protected by topological considerations. however, we encounter a small discrep- ancy between the bps equations and the variational equation of motion. although ”small” in an absolute sense, the mismatch is conceptually significant for the reasons elaborated below. the above conclusions, drawn from field theoretic analysis, will be corroborated and quantified explicitly in a collective coordinate framework. it appears natural to attribute the above mentioned problem to the definition of the energy functional of the nc cp( ) model in particular, and of the nc field theories in general, (since the bps equations are derived directly from the energy of the system). as it is well known, there are complications in the definition of the energy-momentum (em) tensor in nc field theory [ , ]. in general, it is not possible to obtain a symmetric, gauge invariant and conserved em tensor. there are two forms of em tensor in vogue: a manifestly symmetric form [ ], obtained from the variation of the action with respect to the metric, and the canonical form [ ], following the noether prescription. the former is covariantly conserved whereas the latter is conserved. interestingly, we find that in the particular case that we are considering, that is nc cp( ) model in + -dimensions, with only spatial noncommutativity, expressions for the static energy, obtained from both the derivations, are identical. moreover the expression for energy is gauge invariant. we show that there is a bogomolny like lower bound in the energy. however, the subsequently derived bps equations (that saturate the lower bound), does not fully satisfy the equation of motion. let us put our work in its proper perspective. as such, our result in no way questions the consistency of the existing literature [ ] on cp( ) solitons since our model differs crucially from the one considered in [ ]. in particular, we have adopted a different nc generalization of the cp( ) constraint. (we have provided conceptual and technical reasons for allowing such a difference.) thus it is not expected that the results of [ ] will be reproduced. in fact, the energy profile of the localized structure that we uncover, is more sharply peaked and has an o(θ) correction, with respect to the ordinary spacetime cp( ) soliton. (this will be made explicit in the collective coordinate analysis at the end.) surprisingly, the bps equations remain unchanged, although the variational equation of motion is altered. all the same, we emphasize that, we have provided a well defined nc gauge theory, which conforms to the expected features of such a system. hence, the clash between the bps equations and the equation of motion that is revealed here, can have a deeper bearing on the structure of a general nc gauge theory, indicating that the traditional lore of field theory in ordinary spacetme should be applied with greater care in the context of nc field theory. our methodology and its difference from the existing one [ ] is explained below. there are two basic approaches in studying an nc field theory: (i) the appropriate nc field theory is constructed in terms of nc analogue fields (ψ̂) of the fields (ψ) with the replacement of ordinary products of fields (ψϕ), by the moyal-weyl ∗-product (ψ̂ ∗ ϕ̂), ψ̂(x)∗ϕ̂(x) = e i θµν ∂σµ ∂ξν ψ̂(x+σ)ϕ̂(x+ξ) |σ=ξ= = ψ̂(x)ϕ̂(x) + i θρσ∂ρψ̂(x)∂σϕ̂(x) + o(θ ). ( ) the hatted variables are nc degrees of freedom. we take θρσ to be a real constant antisymmet- ric tensor, as is customary [ ], (but this need not always be the case [ ]). the nc spacetime follows from the above definition, [xρ,xσ]∗ = iθ ρσ. ( ) note that the effects of spacetime noncommutativity has been accounted for by the introduc- tion of thr ∗-product. for gauge theories the seiberg-witten map [ ] plays a crucial role in connecting φ̂(x) to φ(x). this formalism allows us to study the effects of noncommutativity as θρσ dependent interaction terms in an ordinary spacetime field theory format. this is the prescription we will follow. (ii) an alternative framework is to treat the nc theories as systems of operator valued fields and to directly work with operators on the quantum phase space, characterized by the non- commutativity condition ( ). on the nc plane, the coordinates satisfy a heisenberg algebra [x ,x ]∗ = x ∗x −x ∗x = iθ = i� θ = iθ which in the complex coordinates reduces to the creation annihilation operator algebra for the simple harmonic oscillator. thus to a function in the nc spacetime, through weyl transform, one associates an operator acting on the hilbert space, in a basis of a simple harmonic oscillator eigenstates. the investigations on the nc cp solitons carried out so far [ , ] exploit the latter method. as it turns out, a major advantage is that structurally, the nc system with its dynamical equations, energy functionals etc., are similar to their ordinary spacetime counterpart. this happens because the ∗-products of (i) are replaced by operator products in (ii) and the spacetime integrals are replaced by trace over the basis states in the hilbert space. in the present work, our aim is to study the nc cp solitons in the former field theoretic approach. from past experiences [ ] we know this to be a perfectly viable formalism. indeed, since the nc spacetime physics is not that much familiar or well understood, it is imperative that one explores different avenues to reach the same goal, to gain further insights. also we would like to point out that since solitons are already present in the cp model at θ = (i.e. ordinary spacetime), unlike the noncommutative solitons of the scalar theory [ ] it is natural to analyze the fate of the solitons under a small perturbation, (which is a small value of θ in the present case). the small θ-results of [ , ] are perfectly well defined. the paper is organized as follows: section ii contains a short recapitulation of the cp( ) solitons. this will help us fix the notations and in fact, identical procedure will be pursued in the nc theory as well. the detailed construction of our version of the nc cp( ) model is provided in section iii. section iv discusses the energy momentum tensor of the model. section v consists of the bogomolny analysis in the nc theory. section vi is devoted to the collective coordinate analysis. the paper ends with a conclusion in section vii. section ii - cp( ) soliton: a brief digression let us digress briefly on the bps solitons of cp( ) model in ordinary spacetime. later we will proceed with the nc theory in an identical fashion. the gauge invariant action, s = ∫ d x [(dµφ)†dµφ + λ(φ †φ − )], ( ) where dµφ = (∂µ − iaµ)φ defines the covariant derivative and the multiplier λ enforces the constraint, the equation of motion for aµ leads to the identification, aµ = −iφ†∂µφ. ( ) since the ”gauge field” aµ does not have any independent dynamics one is allowed to make the above replacement directly in the action. obviously the infinitesimal gauge transformation of the variables are, δφ† = −iλφ† ; δφ = iλφ ; δaµ = ∂µλ. ( ) from the em tensor tµν = (dµφ) †dνφ + (dνφ) †dµφ − gµν (dσφ)†dσφ, ( ) the total energy can be expressed in the form, e = ∫ d x (| d φ | + | (d ± id )φ | ) ± πn, ( ) where the last term denotes the topological charge n ≡ ∫ d x n(x) = πi ∫ d x �ij (diφ) †djφ = ∫ d x π �ijfij = ∫ d x π f , ( ) corresponding to the conserved topological current. the bogomolny bound follows from ( ), e ≥ π | n |, ( ) with the following saturation conditions (bps equations) obeyed by the soliton, | d φ | =| (d ± id )φ | = . ( ) it can be checked that the solutions of the bps equations belong to a subset of the full set of solutions, that satisfy the variational equation of motion. section iii - construction of the nc cp( ) model let us now enter the noncommutative spacetime. the first task is to generalize the scalar gauge theory ( ) to its nc version, keeping in mind that the latter must be ∗-gauge invariant. the nc action is, ŝ = ∫ d x (d̂µφ̂)† ∗ d̂µφ̂ = ∫ d x (d̂µφ̂)†d̂µφ̂, ( ) where the nc covariant derivative is defined as d̂µφ̂ = ∂µφ̂ − iâµ ∗ φ̂. depending on the positioning of âµ and φ̂, the covariant derivative can act in three ways , d̂µφ̂ = ∂µφ̂ − iâµ ∗ φ̂ = ∂µφ̂ + iφ̂ ∗ âµ = ∂µφ̂ − i(φ̂ ∗ âµ − âµ ∗ φ̂) ( ) which are termed respectively as fundamental, anti-fundamental and adjoint representations. we have chosen the fundamental one. notice that for the time being we have not considered the target space (cp( )) constraint. we will return to this important point later. the nc action ( ) is invariant under the ∗-gauge transformations, δ̂φ̂† = −iλ̂ ∗ φ̂† ; δ̂φ̂ = iλ̂ ∗ φ̂ ; δ̂âµ = ∂µλ̂ + i[λ̂, âµ]∗. ( ) we now exploit the seiberg-witten map [ , ] to revert back to the ordinary spacetime degrees of freedom. the explicit identifications between nc and ordinary spacetime counterparts of the fields, to the lowest non-trivial order in θ are, âµ = aµ + θ σρaρ(∂σaµ − ∂µaσ) φ̂ = φ − θρσaρ∂σφ ; λ̂ = λ − θρσaρ∂σλ. ( ) as stated before, the ”‘hatted”’ variables on the left are nc degrees of freedom and gauge transformation parameter. the higher order terms in θ are kept out of contention as there are certain non-uniqueness involved in the o(θ ) mapping. the significance of the seiberg-witten map is that under an nc or ∗-gauge transformation of âµ by, δ̂âµ = ∂µλ̂ + i[λ̂, âµ]∗, aµ will undergo the transformation δaµ = ∂µλ. subsequently, under this mapping, a gauge invariant object in conventional spacetime will be mapped to its nc counterpart, which will be ∗-gauge invariant. this is crucial as it ensures that the ordinary spacetime action that we recover from the nc action ( ) by applying the this is the first difference between our model and [ ] who use the anti-fundamental representation. in fact, in [ ], it is difficult to proceed with the fundamental definition [ ]. on the other hand, in the present work, the choice between the first and second definition is not very important as it affects the overall sign of θ only. similar type of situation prevails in [ , ]. seiberg-witen map will be gauge invariant. thus the nc action ( ) in ordinary spacetime variables reads, ŝ = ∫ d x[(dµφ)†dµφ + θαβ{fαµ((dβφ)†dµφ + (dµφ)†dβφ) − fαβ (d µφ)†dµφ}] ( ) the above action is manifestly gauge invariant. the equation of motion now satisfied by aµ is, i(− iaµφ†φ + φ†∂µφ − ∂µφ†φ)( − θαβfαβ) + θαµ[∂ α{(dβφ)†dβφ} − ∂β{(dαφ)†dβφ + (dβφ)†dαφ}] − θαβ [∂ α{(dβφ)†dµφ + (dµφ)†dβφ) + if αµ(φ†dβφ − (dβφ)†φ}] = ( ) remember that so far we have not introduced the cp target space constraint in the nc spacetime setup. let us assume the constraint to be identical to the ordinary spacetime one, i.e., φ†φ = . ( ) the reasoning is as follows. primarily, after utilizing the seiberg-witten map, we have returned to the ordinary spacetime and its associated dynamical variables and the effects of noncommu- tativity appears only as additional interaction terms in the action. hence it is natural to keep the cp constraint unchanged. alternatively, the above assumption can also be motivated in a roundabout way. remember that the the cp( ) constraint has to be introduced in a ∗-gauge invariant way. in order to introduce the cp constraint directly in the nc action ( ) or ( ), the constraint term ∫ λ(φ†φ − ) has to be generalized to a ∗-gauge invariant one by the application of the (inverse) seiberg-witten map. this is quite straightforward but needless because as soon as we apply the seiberg-witten map to the ∗-gauge invariant constraint term, we recover the earlier ordinary spacetime constraint. this allows us to write, aµ = −iφ†∂µφ + aµ(θ) ( ) with aµ denoting the o(θ) correction, obtained from ( , ). for θ = . aµ reduces to its original form. note that aµ is gauge invariant. thus the u( ) gauge transformation of aµ remains intact, at least to o(θ). keeping in mind the constraint φ †φ = , let us now substitute( ) in the nc action ( ). since we are concerned only with the o(θ) correction, in the θ-term of the action, we can use aµ = −iφ†∂µφ. however, in the first term in the action, we must incorporate the full expression for aµ given in ( ). remarkably, the constraint condition conspire to cancel the effect of the o(θ) correction term aµ. finally it boils down to the following: the action for the nc cp model to o(θ) is given by ( ) with the identification aµ = −iφ†∂µφ and φ†φ = . this is the second difference between our model and that of [ ], where θ-correction terms are present in the cp ( ) constraint. this is a serious difference as it drastically alters the structures of the model in [ ] from ours. apart from the conceptual reasoning given above, there also appears a technical compulsion. we would like to obtain perturbative θ- corrections to the ordinary spacetime cp ( ) model. incorprtating θ- corrections in the cp ( ) constraint as in [ ] in our system will lead to a differential equation for the multiplier λ, instead of an algebraic one as in the ordinary spacetime case. this will change the φ- equation of motion in a qualitative way. we stress that our model is a perfectly well defined nc theory which, incidentally, is distinct from the existing nc cp ( ) model [ ]. section iv - energy-momentum tensor for the nc cp( ) model our aim is to study the possibility of soliton solutions for the action ( ). let us try to derive the bogolmony bound and bps equations in the present case. the first task is to compute the em tensor. we follow [ ] in computing the symmetric form of the em tensor by coupling the model with a weak gravitational field and get, t sµν = ( − θαβfαβ )[(dµφ) †dνφ+(dνφ) †dµφ−gµν (dσφ)†dσφ]+ θαβ [fαµ((dβφ) †dνφ+(dνφ) †dβφ) +fαν ((dβφ) †dµφ + (dµφ) †dβφ) − gµνfασ((dβφ)†dσφ + (dσφ)†dβφ)]. ( ) the t sµν stands for the symmetric form of the em tensor. in the static situation, φ̇ = → a = f i = d φ = and the static energy density simplifies to, t s = ( + θ f )(d iφ)†diφ, ( ) where fµν is also expressible in the form fµν = −i[(dµφ)†dνφ − (dνφ)†dµφ] = −i[(∂µφ)†∂νφ − (∂νφ)†∂µφ]. now we discuss the canonical form of the em tensor. remembering that the indices of adjacent φ’s are summed, the expanded form of the lagrangian is, l̂ = (dµφ)†dµφ + λ(φ †φ − ) − i θαβ [ ∂µφ †∂βφ∂αφ †∂µφ + ∂µφ †∂βφφ †∂αφφ †∂µφ− ∂βφ†∂µφφ†∂αφφ†∂µφ−∂αφ†∂βφ∂µφ†∂µφ−∂αφ†∂βφφ†∂µφφ†∂µφ]. ( ) the canonical energy-momentum tensor is, tµν = δl̂ δ(∂µφ†) ∂νφ † + δl̂ δ(∂µφ) ∂νφ − gµνl̂ = ( − θαβfαβ )(dµφ †dνφ + (µ ↔ ν)) −iθαβ [∂νφ†∂βφ(∂αφ†∂µφ + φ†∂αφφ†∂µφ) + (µ ↔ ν) − ∂βφ†∂νφφ†∂αφφ†∂µφ − (µ ↔ ν)] −iθµα[(− ∂νφ †∂αφ + ∂αφ†∂νφ)(d µφ)†dµφ − ∂σφ†∂νφ(∂αφ†∂σφ + φ†∂αφφ†∂σφ) +∂σφ †∂αφ(∂νφ †∂σφ+φ†∂νφφ †∂σφ) +∂νφ †∂σφφ †∂αφφ†∂σφ−∂αφ†∂σφφ†∂νφφ†∂σφ]−gµνl̂. ( ) note that θαβ part is symmetric. in the energy density t the contribution coming from the non-symmetric parts in the θ-contribution drop out if only space-space noncommutativity is assumed, i.e. θ i = . for this special case, in the static limit, the above θ-contribution completely drops out and the energy density reduces to t n = −l̂ = ( + θ f )(d iφ)†diφ. ( ) clearly this is identical to the static energy ( ) obtained from the the symmetric form t sµν . indeed, it is satisfying that in this particular case, both the canonical and symmetric forms of the em tensor lead to the same expression of the static energy, which is manifestly gauge invariant and conserved (as it comes from the canonical form). interestingly to o(θ), the noncommutativity effect factors out from the ordinary spacetime result. also notice that in the two spatial dimensions that we are considering, the θ-term in the energy density is proportional to the topological charge density n(x) in ( ). this is because the expression for the topological current remains unchanged since the dynamical variables as well as the cp( ) constraint is unaltered in our model. we specialize to only space-space noncommutativity, θij = θ�ij , θ i = , and find, t (θ) = πθn(x)(d iφ)†diφ, ( ) where the superscript s or n is dropped. section v - analysis of the bogomolny bound in order to obtain the bogomolny bound, we follow the same procedure as that of the cp model in ordinary spacetime and rewrite the static energy functional in the following form, e = ∫ d x ( + πθn)[| (d ± id )φ | ± πn] = ∫ d x [( + πθn) | (d ± id )φ | ] ± πn ± π θn ] = ∫ d x ( + πθn) | (d ± id )φ | ± πn ± π θ ∫ d x n (x) + o(θ ). ( ) now individually all the terms in the energy expression are positive definite. hence we obtain the bogomolny bound to be e ≥ n + π θ ∫ d x n (x) ( ) and the saturation condition is ( + πθn) | (d ± id )φ | = . ( ) the bps equation turns out to be, d φ = ±id φ. ( ) thus we find that the bps equation remains unchanged and there is a o(θ) correction in the static energy of the soliton. note that both of the above results do not agree with [ , ]. but this is not unexpected since as we have mentioned before, the defining conditions of the nc cp( ) models are different. however, we repeat that a priori there is nothing inconsistent in our nc model. finally, we are ready to discuss the curiosity. it appears that the bps equations ( ) do not satisfy the equation of motion for φ. a straightforward computation yields the dynamical equation for φ, dµ[( − θαβf αβ)dµφ] + θαβ [idα{(dσφ)†dσφdβφ} + dβ{fαµdµφ} + dµ{fαµdβφ} −idα{(dβφ)†dµφ+ (dµφ)†dβφ)dµφ}+idµ{(dβφ)†dµφ+ (dµφ)†dβφ)dαφ}]−λφ = . ( ) (details of the derivation are provided in the appendix.) to get λ, contract by φ† and use φ†φ = . for the time being, instead of writing the full equation of motion, we want to check the consistency of the programme only, that is whether the solution of the bps equation satisfies the equation of motion, which they should. since the bps equation remains unchanged here, the θ-term in the equation of motion should vanish for those solutions that satisfy the bps equation as well. so we consider the equation of motion in a simplified setting where the bps equation is satisfied and only θ is non- zero and obtain for λ λ = φ†didiφ + θ φ†di(f diφ). ( ) putting λ back in the equation of motion, we get didiφ − φ†didiφφ + θ [di(f diφ) − φ†di(f diφ)φ] = . ( ) this equation can be rewritten as didiφ − φ†didiφφ + θ [∂if diφ − φ†∂if diφφ + f (didiφ − φ†didiφφ)] = . ( ) clearly the last term, that is θ f (d idiφ − φ†didiφφ) ≈ o(θ ) and can be dropped. the term θ φ†∂if diφφ = θ ∂if φ†diφφ = . however the remaining o(θ)-term, θ ∂if diφ does not vanish. this is the purported mismatch between the bps equations and the full equation of motion. this brings us to the last part - the collective coordinate analysis, where we can check explicitly the above conclusions in a simplified setup. section vi - collective coordinate analysis we consider the topological charge n = sector. as we have discussed before, expression for the topological current and subsequently the charge remains same (in our nc cp( ) model) as that of the ordinary spacetime cp( ) model. this means that we can use the same parameterizations as before [ ] to introduce the collective coordinates. as a first approximation, only the zero mode arising from the global u( ) invariance is being quantized. in the o( ) nonlinear sigma model, the n = sector is characterized by [ ] na = {r̂sin(g(r)),cos(g(r))} ; a = , , with the constraint nana = and the boundary conditions g( ) = ; g(∞) = π. keeping in mind the o( )−cp( ) duality and the hopf map na = φ†σaφ, the soliton profile in the cp( ) variables is of the form, φ ≡ ( φ φ ) = ( cos( g ) sin( g )ei(ϕ+α(t)) ) ( ) where the gauge (φ )∗ = φ has been used and r,ϕ refer to the plane polar coordinates. α(t) is the collective coordinate. substituting the above choice ( ) in the static energy expression in ( ) leads to, e(r) = ( + θ sin(g)g′ r )[(g′) + sin (g) r ], ( ) where g′ = dg dr . in figure ( ) the effect of the θ- correction is shown where the following simple form of g(r) is considered, g(r) ≈ π( − e−µr). ( ) one can clearly see that with typical values of the parameters, (θ = , µ = ) the energy density for the nc case is more sharply peaked. (in reality, θ should be smaller.) this assures us of the rationale of our previous bogolmony analysis. next we look in to the equation of motion. it is straightforward check that the profile ( ) satisfies the bps equation as well as the equation of motion for the ordinary spacetime situation, θ = . for θ = , the bps equations are once again satisfied since they remain unaltered. so we concentrate only on the problem term θ ∂if diφ in the equation of motion ( ). with the particular form of g(r) in ( ) we obtain θ ∂if diφ = θg′ [ g′′ r sin( g )− g ′ r sin( g ) + (g′) r cos( g )] ( sin( g ) −cos( g )eiϕ ) ≡ ( x(r) y (r) ) . ( ) in figure we again use the g(r) given in ( ) and compare the magnitude of the above expression with a typical term, ∂i∂iφ ≡ ( s(r) t(r) ) , occurring in the equation of motion ( ). for consistency, the expressions in ( ) should have vanished. however, even for θ = , (which is quite a large value), the mismatch term is small in an absolute sense. section vii - conclusions in this paper, we have attempted to recover the soliton solutions in the non- commutative cp( ) model, discovered earlier [ ]. the u( ) and nc u( ) gauge invariances in the cp( ) and nc cp( ) models respectively, requires the use of the seiberg-witten map, to convert the nc action to an action comprising of ordinary spacetime dynamical variables. the effects of noncommutativity are manifested as interaction terms. for theoretical as well as technical reasons, we found it convenient to keep the cp( ) constraint unchanged, i.e. without any θ correction. from the above action, we construct both the symmetric and canonical forms of the energy momentum tensor. for only spatial noncommutativity, both the above forms reduce to an identical (gauge invariant) expression for the static energy. the bogomolny analysis yields a lower bound in the energy, hinting at the presence of a new type of soliton. however, the resulting bps equations do not match completely with the full variational equation of motion. the present model is otherwise a perfectly well defined nc field theory with the expected features. hence we conclude that inadequacy in the definitions of the energy momentum tensor in an nc field theory is responsible for this failure. the above phenomena are nicely visualized in a collective coordinate framework. the above awkward situation clearly demands further study. finally, as a future work we mention that inclusion of the hopf term, (in the form of chern- simons term in cp( ) variables), in the nc theory would indeed be interesting. the hopf term was introduced [ , ] to impart anyonic behavior to the cp( ) solitons. the exact form of the nc version of the chern simons term is known [ ] - it is a ”non-abelian” generalization of the chern simons term. in our formalism, application of the seiberg-witten map will reduce it to the ordinary chern simons term [ ] but there will appear o(θ) correction terms since the gauge field of the chern simons term is actually a non-linear combination of the cp( ) variables. another interesting problem is the reconstruction of the nc cp( ) model of [ ] in our framework. appendix: to get the φ-equation of motion, we consider variation of φ†. and exploit the relations, (dµφ)†φ = φ†dµφ = , ( ) δ(dµφ)† = δ(∂µφ† + (φ†∂µφ)φ†) = ∂µ(δφ†) + (δφ†∂µφ)φ† + (φ†∂µφ)δφ† δ(dµφ) = δ(∂µφ − (φ†∂µφ)φ) = −(δφ†∂µφ)φ). ( ) in the action the terms are products of the generic form ∫ (dµφ)†(dνφ)x(x). the variation of (dµφ) will reproduce ∫ (dµφ)†δ(dνφ)x = − ∫ (dµφ)†φ(δφ†∂µφ)x = , by using ( ). similarly, the variation of (dµφ)† will yield ∫ δ(dµφ)†(dνφ)x = ∫ (∂µ(δφ†) + (δφ†∂µφ)φ† + (φ†∂µφ)δφ†)dνφx = − ∫ δφ†dµ(dνφx) by partial integration and using ( ). the above identities simplifies the computations consid- erably and leads to the equation ( ). acknowledgements: it is a pleasure to thank professor hyun seok yang for fruitful correspondence. also i thank professor avinash khare for a helpful discussion. lastly i am indebted to bishwajit chakraborty for a free access to his notes on cp( ) model. references [ ] n.seiberg and e.witten, jhep ( ) . [ ] for reviews see for example m.r.douglas and n.a.nekrasov, rev.mod.phys. ( ) ; r.j.szabo, quantum field theory on noncommutative spaces, hep-th/ . [ ] j.polchinski, phys.rev.lett. ( ) . [ ] c.s.chu and p.-m.ho, nucl.phys. b ( ) ; v.schomerus, jhep ( ) ; r.banerjee, b.chakraborty and s.ghosh, phys.lett. b ( ) . [ ] s.minwalla, m. van raamsdonk and n.seiberg, noncommutative perturbative dynamics, hep-th/ . [ ] r.gopakumar, s.minwalla and a.strominger, jhep ( ) . [ ] b.-h.lee, k.lee and h.s.yang, phys.lett. b ( ) ; k.furuta et al., low energy dy- namics of noncommutative cp solitons in + dimensions, hep-th/ ; h.otsu et al., new bps solitons in + dimensional noncommutative cp model, hep-th/ . [ ] m.bowick, d.karabali and l.c.r.vijewardhana, nucl.phys. b ( ) . [ ] j.m.grimstrup et. al., hep-th/ . [ ] a.das and j.frenkel, phys.rev.d ( ) (hep-th/ ). [ ] h.s.snyder, phys.rev. ( ) . for some later works, see for example s.doplicher, k.fredenhagen and j.e.roberts, phys.lett. b( ) ; k.morita lorentz-invariant noncommutative qed, hep-th/ ; s.ghosh, phys.rev. d ( ). [ ] j.murugan and r.adams, comments on noncommutative sigma models, hep-th/ . [ ] s.ghosh, phys.lett. b ( ) ; ibid ( ) . [ ] h.s.yang, private communications. [ ] n.grandi and g.a silva, phys.lett. b( ) . [ ] b.jurco et al., hep-th/ . [ ] see also, b.chakraborty, s.ghosh and r.p.malik, nucl.phys. b ( ) ; b.chakraborty, mod.phys.lett. a ( ) . an analysis of led light distribution based on visual spectral characteristics procedia engineering ( ) – - © published by elsevier ltd. doi: . /j.proeng. . . available online at www.sciencedirect.com available online at www.sciencedirect.com procedia engineering procedia engineering ( ) – www.elsevier.com/locate/procedia advanced in control engineering and information science an analysis of led light distribution based on visual spectral characteristics xu xiaobing,xu huamei,wang jianping,zhu chenghui,xie yunlin a* school of electrical engineering and automation, hefei university of technology, ,hefei,china abstract on the analysis of the human visual structure characteristics and led optical design principle, human visual color image model with background light was constructed in this paper, and the image sharpness function is defined. with high pressure sodium lamps, white light and green light led as backlight, the model simulation of image sharpness is fulfilled. the results show that the green led has better clarity and sensitivity with the same condition of radiation energy background light. . © published by elsevier ltd. selection and/or peer-review under responsibility of [ceis ] keywords: human visual characteristics; green led; visual model of color images . introduction since the seventies there has been the world's energy crisis, countries have to take corresponding measures and actively develop new energy sources, do everything possible to conserve existing energy [ ]. reflects the green light is the core of energy efficient lighting, reasonable to select the correct power source is the key to achieving the green light [ ].led (light emitting diode, led) is a new and efficient solid light source. its emergence is recognized as the most promising in the st century one of the areas of high technology [ ]. led lighting in a variety of more and more people's attention, especially in the development of high-power high-brightness led lighting has become the development trend of new * corresponding author .tel.: + . e-mail address:weahhf@ .com open access under cc by-nc-nd license. open access under cc by-nc-nd license. http://creativecommons.org/licenses/by-nc-nd/ . / http://creativecommons.org/licenses/by-nc-nd/ . / xu xiaobing et al. / procedia engineering ( ) – xu xiaobing et al./ procedia engineering ( ) – generation of civil [ ]. in china, the road currently used mainly high pressure sodium light sources, but the light blue-green light color shade component composition containing less sensitive areas outside of the human eye at night in front of the driver is not easy panduan cars, pedestrians, obstacles, etc. distance, high incidence of traffic accidents [ ]. many researchers state in the mesopic vision of high pressure sodium, metal halide light, as the efficiency of the study, achieved many result [ ]. but in research new led optical characteristics is inadequate, in this paper analyzes the structural characteristics of human visual design of a consistent feature of human vision led lighting, the green led lighting, so that the lamp with the light color components the proportion of green light more, and the distribution of sensitive areas in the human eye, to make up for the lack of yellow high-pressure sodium lamp, the light and colors of light through this model, experimental simulation, obtained better results. . the visual structure of the human eye the structure of the human eye, including: cornea, iris, lens, ofitreous, retina and adtic nerve. the retina is the visual optical and electrical physiological processes during the interface. it divided into cone cells and rod cells. the former well under the conditions specified in the visual detail and color resolution, while the latter has higher sensitivity can feel a very faint light, but can not distinguish the details and colors, the main in the case of dark play. pyramidal cells in the human eye work, the brightness level of cd / ㎡ above vision is called photopic vision. rodshaped cells work in the human eye, the brightness level . cd / ㎡. between photopic and scotopic vision are called mesopic vision. . green led's light color design principles green led light color design in the mesopic vision range, the human eye cone cells and rod cells are simultaneously and the spectral wavelengths of light in different colors depending on the efficiency of different sensitivities. scotopic vision and photopic vision of the spectrum of light are as the efficiency curve v '(λ) and v (λ) are determined the in cie and , respectively as shown in fig. (a): fig. . (a) two visual spectral efficiency of light as light as the performance; (b) cones in the human eye's sensitivity to a variety of different color curves. as shown in fig. (a), in the photopic visual conditions, the human eye is most sensitive to nm wavelength green light and lumineous efficiency of lm / w; but with the lower level of the human eye adapt to light and shade, color, space and response features as the feelings have to change, the human eye fovea and the edge detection becomes as easy as some of the perceived, and color perception gradually weakened, while the human eye will make the most sensitive optical wavelength from the min nm of the green vision when the maximum efficiency, and gradually change to scotopic vision of the nm the xu xiaobing et al. / procedia engineering ( ) – xu xiaobing et al./ procedia engineering ( ) – most efficient. so according to this characteristic, if the light source of the radiation spectrum of content and blue-green shade, you can make much more eye pupil contraction, it will have a better visual effect. . . model of human visual analysis of color images pyramidal cells in the human eye to various different colors of light relative sensitivity curve shown in fig. (b): it reflects the energy equivalent to the human eye to different wavelengths of light relative visual sensitivity. reference [ ] table provides the data for intermediate vision research, the use of least squares data fitting, you can get the middle of the visual spectrum of light as the performance curve shown in fig. : fig. . spectrum of luminous efficiency it reflects a certain brightness level and the wavelength of light depending on the relationship between performance. eye on the overall strength of the feelings of colored light can be sensitive to each color intensity of the visual cells integrated into a synthesis of the impulse to pass into the brain, and then produced a color image. the visual model of color image shown in fig. : fig. . visual model of color image the function of this model to simulate the human eye for color images to achieve the process of perception, according to the input of different r, g, b values, the human eye can see different colors and brightness of the color image, r, g, b expression is as follows: ( ) ( ) λλλ drsr m∫ Κ= g ( ) ( ) ( ) λλλ dgsm∫ Κ= ( ) ( ) λλλ dbsb m∫ Κ= ( ) according to the literature [ ] as the performance of the mescopic vision, combined with visual selection between the scope of this article, values for the lm / w; mΚ λs is the mesopic vision spectrum of light as the effectiveness of distribution; ( )λr , ( )λg ( )λb, represent the red, green, and blue sensitivity of cells to different wavelengths. perception of color images is as follows: ) chromatic adaptation transform ） non-linear compression ） color separation xu xiaobing et al. / procedia engineering ( ) – xu xiaobing et al./ procedia engineering ( ) – ( ) iik ek ） spatial filter processing filter selected the following equation: ∑=Η ωξξ , ( ) where ( )[ ] /exp iii ke σξξ +−= , κ is the coefficient of factor accumulation and to make the filter ,the coefficient factor is accumulation to . parametersie iσ and iω are used to change the size of the filter. ） color image output. . . the definition of image resolution in recent years, researchers through the ambiguity and noise on the clarity of the definition [ ], this image based on this model output resolution is defined as follows: bxbxyxd ++= x ( ) d: image clarity, the greater the value is the clearer of image. y: the image brightness, the range of . ~ cd / ㎡ . b , b : represent the red-green and yellow-blue contrast, in the range between - . , , : respectively coefficient and . x x =++ xxx . simulation examples . . simulation model selection ） the background radiation in the same energy , model a and b parameters are chosen as follows: ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎣ ⎡ −= . . . . . . . . . a ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎣ ⎡ − −= . . . . . . . . . b ） spatial filter parameters are as the following table: table spatial filter parameter channel iω iσ black and white . . . . - . . red and green . . . . yellow and blue . . . . xu xiaobing et al. / procedia engineering ( ) – xu xiaobing et al./ procedia engineering ( ) – . . analysis of simulation results table experimental results channel hps led white light led green light y . . . b . . . b . . . d（definition） . . . we carried it through the software matlab . simulated results are as follows: fig. . (a) original image; (b) led green light; (c) hps; (d) led white light. . conclusion based on the analysis of the structure in human vision and sensitivity, the different wavelength is different from the design of a green led lighting. through modeling is simulation of the high-pressure sodium lamp, yellow and white led, green led. then carried out by matlab . simulation of light and color, from the comparative analysis of the results obtained the green led at the same level of brightness, the clarity is better than high pressure sodium lamp and white led, it is more suitable for road lighting can achieve the best results. references [ ] bing treekui, jie gao. led lighting engineering [j]. illuminating engineering journal, vol. , no. , , ~ . [ ] liu yaobin, hu guanmin. china's led industry status, trends and strategic choice [j]. science technology progress and policy, vol. , no. , , ~ . [ ] zhao xing, fang zhiliang, mu guoguang. led projection light source chromaticity characteristics [j], physics vol. , no. , , ~ . [ ] chen zhonglin. with a visual road lighting research [j], lamps and lighting, , ~ . [ ] zhou taiming, lin yandan. light spectrum and low-light level based on the mesopic vision [j], china illuminating engineering journal, vol. , no. , , ~ . [ ] liu oingxiang, jiang-day hair. color and grayscale conversion algorithm between images [j], wuhan university of technology (transportation science & engineering), vol. , no. , , ~ . [ ] han bo. based on digital image processing [m], tsinghua university press, . [ ] chen zhonglin, hu yingkui. mesopic vision performance of the maximum of the light [j], chongqing architecture university,vol. ,no. , , ~ . [ ] cao yang, yuan zongjie, lin yandan and so on. visual function method in road lighting application [j], china illuminating engineering journal, vol. , no. , , ~ . [ ] hut, cu, npl. performance based model for mesopic photometry [r]. finland: helsinki university of technology, . v- - .indd © nature publishing group nature vol. may correspondence club of rome sir,- -the editorial in nature of march ( , ; ) gives a brief review of the voluminous report of the science policy research unit of the university of sussex on the limits of growth (futures, march ), and calls it, hope- fully, "almost the last word on the club of rome". this is liable to give a false impression of the club of rome, of the limits and to some extent even of the sussex report. in my opinion the sussex report is not so much an axe as, rather, so far the best constructive critique of the limits. it is fair, courteous and thorough. marie jahoda in her "post- script on social change" writes, "we know from our experience in studying forrester's and meadows's work that it took a group of highly trained experts in a variety of fields many months of hard effort to grasp fully the technique, the assumptions and the shortcomings of world dynamics". almost every page of the report bears this out. it is a very welcome change after the whole- sale rejection of world dynamics and the limits by many economists, whom one must strongly suspect of not having read the books, but just leafed through them with disgust. the sussex group have read them, digested them and much of what they write, though not all of it, can be considered as a fair commentary, which will give the reader a deeper understanding of these works, while showing up some of their weaknesses. the least satisfactory are the com- puter runs of the sussex group. they cast doubt on the reliability of the world models by running them backward, with the result that they "retrodict" a cata- strophe in the past. i need not deal with this, as it has been answered by meadows in the same number of futures. an error of i , in some parameters is liable to make the model run off its track in the past, while an error of the same order would be hardly noticeable in a forecast. the forrester-meadows models share this property with many other complicated physical systems. nor need we be impressed with the difference which they find in forecasts by substi- tuting expanding in place of shrinking resources. this is not a "small change" in the assumptions. on the other hand, in view of what we have experienced from economists, it is an agreeable surprise to find that chapter , the capital and industrial output system by christopher freeman with the economists julien and cooper, is particularly constructive. they make it clear that it is hopeless to treat an aggregated system, in which africans and americans are lumped together, dynamically with a single set of opera- tors. this is macroeconomics taken too far. one cannot expect from such a forcibly homogenized model anything but coarse approximations, and nothing more has ever been claimed by its authors. this type of critique, of which there are many more examples in the long report, is welcome to the club of rome as a dialectical aid towards the next step. it does not find us at all unpre- pared. we have never considered the world models as oracles of unescapable fate. perhaps the words "predicament of mankind" were misleading. a pre- dicament is not a trap from which one can never escape ; it was meant to be a warning and a challenge. a warning against "ostrichism" and a challenge to take up the fight with the dangers which have been revealed. as far as i can see, the sussex report nowhere states that the dangers are imaginary, though it often suggests that they might be exaggerated. are they exaggerated? i think that if the club of rome has anything with which to reproach itself, it is rather that it has not warned in time that while the global danger may be a hundred years ahead, its first serious wave is right upon us. we are far from living in a unified world in which the resources are equitably or at least reasonably shared. while the club of rome warned of an overshoot in the consumption of non- renewable resources some time in the next century, the highly industrialized nations and in particular the united states have long overshot the limit at which they could live safely within their own means. a grave fuel and energy crisis is now striking at the industrialized countries, long before the resources of the world are exhausted-because we have not foreseen it in time. the fuel and energy crisis which is starting now is likely to last for two decades, and it is scant satisfaction for us of the club of rome that from now on we are likely to meet much less complacency, much less of the "i am all right, jack ! " attitude. when the sussex group states that it considers the political difficulties as more urgent and important than the physical limits, it is in perfect agreement with the club of rome. from the start its founders have considered international cooperation as their most important target, and they were successful in establishing a world- wide network of intellects, not entirely without political influence. there are many minor deficiencies in the forrester-meadows models which could be amended, but it is clear that no aggregated world model can be satisfactory. the club of rome has long understood this, and now, among other projects, it is sponsoring a refdon- alized computer model of the world. this ambitious project, headed by pro- fessors mesarovic and peste!, divides the world into regions, taking account of their self-interest and also of their political philosophy. if success- ful, this project may give answers to many questions which the limits have left open. only one thing is certain ; the dangers, the instabilities, will be found very much nearer to us than the global physical limits. as regards the ultimate, physical limits, we believe that these can be pushed further away, but we are not satisfied with pious hopes. the club of rome is going ahead with plans for mobilizing creative technology in all countries. we are not "doomwatchers" but doomfighters. yours faithfully, imperial collef:e, london dennis gabor princeton in trouble sm,-many of us at the institute for advanced study were sad to read your leader about princeton (nature, , ; ). not only is your statement of the facts extremely misleading, but also your underlying philosophy is diffi- cult to understand. your writer seems to believe that an academic institution, by its very nature, should be a dictator- ship, and that in case of a conflict be- tween faculty and director the faculty must go. the background of the present dispute can be described briefly as follows. it had been unanimously agreed that the faculty as a whole should supervise the formation of the fledgling "program in social sciences" by examining the credentials of candidates for the first three professorships. precisely because these first appointments would deter- mine the future direction of the pro- gram, it had been agreed that such faculty supervision was essential ; and in fact the program got off to an excel- lent start with the unanimous faculty approval of clifford geertz as the first professor. 	correspondence 	club of rome development of the hybrid operation method of a multi-geothermal heat pump system and absorption chiller-heater energies , , - ; doi: . /en energies issn - www.mdpi.com/journal/energies article development of the hybrid operation method of a multi-geothermal heat pump system and absorption chiller-heater young-ju jung , hyo-jun kim , kyung-ju shin , jae-hun jo , yong-shik kim and young-hum cho ,* department of architectural engineering, graduate school of yeungnam university, daehak-ro, gyeongsan, gyeongbuk , korea; e-mails: nun @naver.com (y.-j.j.); kimyo@ynu.ac.kr (h.-j.k.); shinkeoungju@naver.com (k.-j.s.) department of architectural engineering, inha university, inha-ro, nam-gu, incheon , korea; e-mail: jhjo@inha.ac.kr division of architecture and urban planning, incheon national university, academy-ro, yeonsu-gu, incheon , korea; e-mail: newkim@incheon.ac.kr school of architecture, yeungnam university, daehak-ro, gyeongsan, gyeongbuk , korea * author to whom correspondence should be addressed; e-mail: yhcho@ynu.ac.kr; tel.: + - - - ; fax: + - - - . academic editor: hossam a. gabbar (gaber) received: june / accepted: august / published: august abstract: considerable efforts have been made to reduce the energy consumption of buildings due to the energy crisis, and, the korean government has supported the use of renewable energy through various grants. among the possible renewable energy sources, geothermal energy can be used regardless of the outside weather. therefore, energy consumption can be reduced considerably in summer and winter. despite the increasing use of renewable energy, the use of renewables has not been operating appropriately. therefore, this study examined some of the problems of the operation of renewable energy and some possible improvements. the aim of the study is to evaluate a building containing an actual installed multi-geothermal heat pump (multi-ghp) system, in terms of the energy efficiency. in addition, this study evaluated the present control system and the method of complex operation regarding existing heat sources systems and ghp systems through a simulation. the results can be regarded as the result of a hybrid operation method for the open access energies , improvement of an existing operation. therefore, the multi-ghp system energy use of a hybrid operation condition of the multi-ghp systems and the absorption (abs) chiller-heater system was reduced compared to the operation condition of the multi-ghp system, and the total energy consumption of the heat source equipment was reduced. the proposed operation plan was evaluated after applying the system to a building. these results showed that the efficient operation of a multi-ghp hybrid operation method is possible. as a result, the ghp energy use of multi-ghp systems and the abs chiller-heater system was reduced by % compared to existing operation and the total energy consumption of heat source equipment was reduced by %. keywords: renewable energy; multi-geothermal heat pump (multi-ghp) system; building energy; transient system simulation program (trnsys); hybrid operation; absorption (abs) chiller-heater . introduction the energy crisis in the world economy is a major problem, as published by the international energy agency (iea) in the june mid-term outlook for the oil market report (oil medium-term market report [ ]). the world oil demand is expected to increase by an annual average of . % by . on the other hand, oil is a limited resource. therefore, efforts to replace fossil fuels due to oil depletion are ongoing and necessary. in particular, korea is the world’s th highest energy consumer but it imports more than % of its energy. the percentage of energy in the total amount of imports is increasing gradually. an energy crisis may endanger the economy. consequently, national efforts are needed to respond to the future energy crisis. therefore, the government is fostering a renewable energy industry as a means of handling the energy crisis. the development of renewable energy in a resource poor country is important. among the renewable energy systems available, geothermal energy has been highlighted as highly efficient and safely operable without being effected by outdoor air. in addition, it is one of the oldest renewable energy resources in the world, and it supplies the most energy. studies on the trends of ghp systems and importance of ghp systems are as follows. in the past, many studies have focused on efficiency enhancement and performance evaluations of various ghp systems [ – ]. accordingly, studies of ghp are in progress from many worldwide perspectives. haehnlein et al. [ ] published a comprehensive overview of the current international legal status for the use of shallow geothermal energy. in their study, an international survey was performed using a questionnaire sent to more than countries worldwide. luo et al. [ ] and rees and curtis [ ] examined the importance of the research trends and the design of a ghp system. study on the performance of the ghp systems is as follows. in addition, byun et al. [ ] studied a fuel cell driven ground source heat pump (gshp) system applied in a community building, and the heat pump system performance was analyzed using computational methods. considering the long-term stability of the soil temperature and energy conservation of the system, zhai et al. [ ] suggested that a higher indoor temperature be set for the indoor environment. bakirci et al. [ ] examined the performance of a solar-gshp system with vertical ground handling equipment (ghe). the results suggested that this solar-gshp system can be energies , used for heating applications in the cold climate regions of turkey. yang [ ] assessed the performance characteristics of a vertical u-bend direct-expansion ground source (geothermal) heat pump system (dx gshps) for both heating and cooling. their study highlighted the energy efficiency of the dx gshp system. kim et al. [ ] reported that the design of a proper indoor temperature for variable outdoor conditions is very important for maintaining high system performance and reliability in a hybrid solar-geothermal co heat pump system. ozgener and hepbaslib [ ] examined the energetic and exergetic modeling of gshp systems for system analysis and performance assessments. salvalai [ ] reported a parameter estimation study of a water-to-water heat pump model, implemented in ida indoor climate and energy (ida-ice) simulation environment, is presented and validated using experimental data. some studies on economic evaluation of ghp systems are the following: esen et al. [ ] conducted performance experiments and economic analyses of a horizontal gshp system. a detailed cost analysis was presented and the payback periods when substituting for different local fuel/power sources were determined. studies on the energy efficiency of ghp systems include the following: ally et al. [ , ] provided excellent data on the energy savings and the fraction of energy that could be extracted from the ground for both space heating and water heating. they described the advanced building envelope characteristics, instrumentation, data acquisition, tabulated data collected, analysis, measures of performance, and conclusions for ground-coupled heat pumps for reducing the energy footprint in buildings. chen et al. [ ] discussed an underground water-source water-loop heat-pump (uwswlhp) air-conditioning system for tall apartment buildings in beijing. sivasakthivel et al. [ ] provided extensive data from india highlighting the energy and co saving potential of gshp system. in the case of gshp, the co emissions are between million kg and , million kg, resulting in a reduction of about . % in a year. they estimated that india can save a minimum of gw to , gw of electricity and million tons to , million tons of co emission annually by employing gshp technology. studies on the composite heat source utilizing ghp system are as follows: recognition of the economic and convenient effects of geothermal heating and cooling systems in korea is increasing because renewable energy systems supply business and installation obligations in public buildings. geothermal energy, however, is only in charge of a part of the building load due to the high initial installation cost. moreover, its efficiency is reduced due to the use of independent existing heat sources. accordingly, research into ghp systems is on-going, focusing on increasing the efficiency of underground heat exchangers and evaluating the performance. complex operations combining solar heat and ghp have been studied in korea and abroad. when a complex heat source was used, kong et al. [ ] examined the operation priority based on the energy consumption. hwang et al. [ ], ozgener and hepbasli [ , ], nam [ ], and shu et al. [ ] examined solar heat and ghp systems and suggested an efficient way of operation through performance analysis. ozgener and hepbasli [ , ] assessed the complex operations of existing heat sources systems and ghp systems and reported the optimal capacity selection in terms of energy consumption in the case of design. jeon et al. [ ] reported that the use of a ghp system energy-efficient should be a priority but this study of the method of complex operation was inadequate. yu et al. [ ] evaluated the practical suggestions of complex operations regarding existing heat sources systems and ghp systems. the present study was conducted based on their results. opening and closing of the air handling unit (ahu) added to the control point and sequencing control of the time delay was proposed. energies , on the other hand, operation was not considered when examining the performance of the ghp unit or to reflect the indoor thermal environment. in addition, the focus was adjusted to compare the energy. the debate on the performance improvement of the heat of room environment or equipment is insufficient. kalz et al. [ ] emphasized the substantial impact of auxiliary energy use on the efficiency of heating and cooling performance. kalz et al. [ ] also presented a comprehensive analysis of the heating and cooling concepts of low-energy buildings in terms of energy use, efficiency and occupant thermal comfort. therefore, with reference to the following study was carried out in this study. in addition, the research into complex operations regarding multi-geothermal heat pump (multi-ghp) systems and absorption (abs) chiller-heaters is insufficient. therefore, a hybrid operation method was proposed for a multi-ghp system and abs chiller-heater. in this study, after selecting a building containing an actual installed ghp, the use of ghp systems was maximized in terms of the energy efficiency. this paper proposes and evaluates the methods of hybrid operation regarding abs chiller-heater and ghp systems through simulations. . building and system information . . building information the chosen building is the k-university hospital located in chilgok, gyeongbuk (korea). figure shows the exterior of the building. figure . exterior of the building. energies , as shown in table , the building has three stories below ground and nine above ground and an installed ghp unit with tonne refrigerant (rt) capacity as the renewable energy source. table . summary of the building information. ghp: geothermal heat pump. building name kyungpook university hospital building stories building with three stories below ground and nine above ground building area m total floor area , m ghp system area of installation m installed ghp systems capacity . gj/h ( refrigeration ton) . . system information table lists the room conditions for the heat source system in the building with an installed ghp system ( . gj/h ( refrigeration ton) and an abs chiller . gj/h ( refrigeration ton)). as shown in figure , the heat source water produced in the heat source system was supplied to the fan coil unit (fcu) and ahu, which operates each section in charge. currently, the heat sources system is controlled automatically. both the ghp and abs chiller-heater are operated by a numerical control system based on the hot and cold supply temperature. on the other hand, when the building load is very low, all heat sources systems operate to meet the set temperature and help reduce the problem of energy wastage. table . room conditions. classification temperature (°c) humidity (%) summer winter summer winter ward department department of pharmacy outpatient department operating room recovery room office assembly hall as shown figure , the ghp system of the building is a water-to-water ghp system. an underground heat exchanger is installed in a depth of m, and the number of drilling holes is . table shows the equipment list of the geothermal heat pump system. table shows the schedule of the absorption chiller-heater equipment. energies , figure . schematic diagram of the operation of the target building. figure . schematic diagram of the ghp system. energies , table . multi-ghp system information. equipment number gh- gh- quantity capacity (gj/h) cooling heating cooling heating . . . . entering source temperature (est) (°c) supplied temperature (°c) return water temperature (°c) table . absorption (abs) chiller-heater information. equipment number dac h- dac h- quantity capacity (gj/h) cooling heating cooling heating . . . . cool water (°c) inlet outlet inlet outlet hot water (°c) coolant (°c) . . . development of the hybrid operation method . . multi-geothermal heat pump (multi-ghp) system the power capacity demand of a korean summer is increased due to the increased power demand from air conditioners. on the other hand, there has been a lack of research on reducing the cooling loads to improve the energy efficiency of buildings. in addition, the existing operation plan has a problem with the super cooling phenomenon in buildings due to oversized design of the ahu fan air flow rate, resulting in a waste of energy. this study focused on reducing the air cooling load and developing a new algorithm. the existing operation of a ghp system control method was proposed and evaluated to improve the energy efficiency. . . . existing operation condition of the multi-geothermal heat pump (multi-ghp system) (case - ) as shown in figure a, the problem with the existing operation method was attributed to oversizing of the ahu fan airflow. therefore, the room temperature could not be maintained at the set temperature ( ± °c). to solve this, case - was set up to reset the fan airflow according to the summer cooling load using equation ( ). table shows the resetting of the fan air flow rate. as a result the room temperature was controlled according to the set temperature as shown in the figure b: m: air flow rate (kg/h) qmax: indoor load (kj/h) c: specific heat (kj/(kg·°c)) Δt: temperature difference between supply and ventilation (°c) ∆ ( ) energies , (a) (b) figure . existing operation condition of a room indoor temperature graph (case - ): (a) design air flow rate set point; (b) reset of air flow rate set point. table . reset the air handling unit (ahu) fan air flow rate. unit: kg/h ahu ahu ahu ahu ahu ahu ahu design air flow rate , , , , , , , reset air flow rate , , , , , , , control of the multi-ghp system and abs chiller-heater of the building is accomplished by considering the load side returns water temperature. the cold water outlet temperature of the multi-ghp system and abs chiller-heater is operated to maintain a set point of °c (tset) in summer. that is, when the cold water outlet temperature is lower than the set value ( °c), the ghp system abs chiller operation is stopped and if not less than °c, the heat source system is on/off operated. a heat source system is constructed to match the load temperature setting. accordingly, the heat source system is operated under on/off control. on the other hand, even if there is no load on the ahu space, energy is unnecessarily consumed to meet the chilled water set point temperature. without limiting the water temperature set point to solve this problem, it is important that an operation method be used to reduce the wasted energy. in addition, the multi-ghp system and abs chiller-heater are responsible for a fixed number of ahu. therefore, the existing operations of the target building are separated independently, i.e., the multi-ghp system and abs chiller-heater. in this way, all heat source systems will be operated, even if the load of the building satisfies the efficient ghp only. as a result, energy wastage will occur. figure presents the existing operating status control algorithm. energies , figure . control algorithms of the existing operating condition (case - ). ① multi-ghp system and abs chiller-heater are not operating.  activate the heat pump if it is higher than the set temperature of the heat source system water outlet temperature (tw > tset). determine the operation of the heat source system, depending on the set temperature.  the heat source system maintains the present condition if the cold water outlet temperature is not less than °c. ② multi-ghp system and abs chiller-heater are operating.  when the heat source system cold water outlet temperature is lower than the set point ( °c), stop the heat source system operation.  to match the set temperature, when the heat pump cold water outlet temperature is higher than the set point ( °c), operate the next heat source system. the heat source system stops operation sequentially when the set temperature is lower than the cold water outlet temperature of the heat source system. energies , . . . sequencing operation condition of the multi-geothermal heat pump (multi-ghp) system (case - ) the existing method, regardless of the outside temperature, is operated when the ahu and heat pump to the load side of the return temperature are fixed to °c. on the other hand, the temperature return of the load side results in unnecessary energy consumption. therefore, as shown in table , an operation plan was proposed to increase the efficiency of the heat pump system by reducing the energy consumption. table . summary of the operation cases of the multi-ghp system. case classification case - existing operation condition of multi-ghp system case - sequencing operation condition of multi-ghp system the return temperature control in the ghp can cause problems with the indoor comfort or cause a waste of energy. this is because the multi-ghp system is operated regardless of the load in the indoor space. therefore, if the room temperature fails to conform to a set temperature of °c, a control method is proposed to operate the heat pump by adding one each. figure presents algorithms of the sequencing operation according to the room temperature. if a heat pump is operating in sequence through indoor temperature monitoring, the multi-ghp system can be operated to match the actual load. in addition, the multi-ghp system can be operated to reduce the waste of energy and improve the room comfort. ① multi-ghp system is not operating.  activate the heat pump when the temperature is higher than the set temperature of the ahu space temperature (troom > tr,set). the heat pump is operated sequentially upon failure to share the load of the room with a single heat pump. the abs chiller-heater is operated upon failure to share the load with all heat pumps.  the multi-ghp system maintains the present condition if the ahu space temperature is the set point temperature. ② multi-ghp system is operating.  when the room temperature is lower than the set point (troom ≤ tr,set), stop the sequentially multi-ghp system operation.  to match the set temperature, when air condition room temperature is higher than the set point temperature, operate the next the multi-ghp system additionally (troom > tr,set). energies , figure . control algorithms of the sequencing operation condition of the multi-ghp system. . . combination with multi-geothermal heat pump (multi-ghp) system and an absorption (abs) chiller-heater system the multi-ghp system and abs chiller-heater are separated independently from the existing operation of this building being used. as shown in table , the operation method was proposed to be used in combination with the abs chiller-heater and multi-ghp systems while maximizing the use of the heat pump systems. the energy consumption was compared using two types of case. table . summary of the operation cases of a combination with the multi-ghp systems and the abs chiller-heater system. case classification case - existing operation condition of the multi-ghp systems and the abs chiller-heater system case - hybrid operation condition of the multi-ghp systems and the abs chiller-heater system energies , . . . existing operation condition of the multi-geothermal heat pump (multi-ghp) systems and the absorption (abs) chiller-heater system (case - ) the multi-ghp system and abs chiller-heater are responsible for a fixed number of ahu. therefore, existing operations of the target building are separated independently; the multi-ghp system and abs chiller-heater. in this way, even if the load of the building satisfies only the efficient ghp, all heat source systems will be operated. as a result, energy wastage occurs. . . . hybrid operation condition of the multi-geothermal heat pump (multi-ghp) systems and the absorption (abs) chiller-heater system (case - ) among them, the higher efficiency of the multi-ghp system is selected and integrated with the abs chiller-heater. in other words, a control method is proposed for the hybrid system design of the multi-ghp system with an abs chiller-heater. if the operation of the multi-ghp system is maximized and the abs chiller-heater, i.e., the existing heat source, is minimized, this would result in an increase in energy efficiency. figure presents the control algorithm. figure . hybrid operation method of the multi-ghp system and abs chiller-heater system. ① multi-ghp system is not operating.  activate the heat pump when the temperature is higher than the set temperature of the ahu space temperature (troom > tr,set). the heat pump is operated sequentially upon failure to share energies , the load of a room with a single heat pump. the abs chiller-heater is operated upon failure to share the load with all heat pumps. ② multi-ghp system is operating.  when the room temperature is lower than the set point (troom ≤ tr,set), stop the sequentially multi-ghp system operation.  to match the set temperature, when air condition room temperature is higher than the set point temperature, operate the next multi-ghp system additionally (troom > tr,set).  if the maximum heat pump operation cannot bear the load, activate the abs chiller-heater. . simulations and results . . simulation information building modeling was performed, as shown in figure , using the transient system simulation program (trnsys) d of google sketch-up. as shown in figures and , detailed data was entered into the target building via trnbuild modeling and trnsys studio modeling, the hvac system was implemented. the weather data is from daegu, korea. table shows the components and properties of each wall. in addition, the hospital building heat source equipment operates in the facility h a day. table . material property specifications. classfication construction thick (m) conductivity (w/mk) density (kg/m ) exterior wall granite . . panel . . insulation . . gypboard . . interior wall gypboard . . air . - - gypboard . . floor concrete . . insulation . . figure . building modeling using the sketch up program. energies , figure . trnbuild modeling. figure . transient system simulation program (trnsys) simulation studio modeling. . . . building modeling the aim of this study was to show the operation method of the multi-ghp system can improve the energy efficiency through the trnsys simulation, as shown in figures and [ ]. energies , (a) (b) figure . simulation flow chart of the multi-ghp system: (a) existing operation condition of multi-ghp system (case - ); (b) sequencing operation condition of multi-ghp system (case - ). in the case of water to the water heat pump, a type (water to water heat pump) was used. a type a is a vertical ground heat exchanger. the set point temperature control of the multi-ghp system used a type of on/off controller. the proposed heat pump that implemented the sequencing control according to the room temperature was connected to the control system of an existing operating system. for case - , the implemented outdoor reset control connects to the control system of an existing to the control system of an existing operating system from the outside temperature. in addition, the proposed heat pump used a type device for the time delay and reflected the ambient temperature, which was performed sequentially using the equation for control. energies , case - is the existing operating method for the separate abs chiller-heater and multi-ghp system. the type (absorption chiller) and type (gas boiler) of trnsys were used in the case of the abs chiller-heater. figure a presents a schematic diagram of the simulation. as shown in figure b, case - , which was simulated by modeling a single system, combines the abs chiller-heater and a multi-ghp system that is separated and independent. (a) (b) figure . simulation flow chart of a combination with the multi-ghp system and an abs chiller-heater system: (a) existing operation condition of the multi-ghp system and abs chiller-heater system (case - ); (b) sequencing operation condition of the multi-ghp system and abs chiller-heater system (case - ). energies , . . . simulation validation according to equations ( )–( ), mean bias error (mbe) and coefficient of variation of root mean square error (cv (rmse)), which is one of the statistical methods compared to the actual data, were used to evaluate the results of the simulations. the corresponding equations are as follows: where: sint: simulation data (kwh) mint: actual data (kwh) nint: the total number of actual data according to the ashrae guideline [ ], the simulation results of the building are reliable if the results entered in the range of table are comparable to the actual data results. the actual target for the building’s electricity usage in august was approximately , kwh, and a simulation of the electricity usage was approximately , kwh. this result compares well with the value of the simulation and actual power capacity; the simulation value was calculated to be . % of that actually measured. in other words, the mbe value was approximately − . % and the cv (rmse) values were approximately . %. therefore, the results of the simulations can be considered as accurate. table . simulation validation result. calibration type index acceptable value result monthly mbe month ± % − . % cv (rmse month) % . % . . simulation result . . . operation cases of the multi-geothermal heat pump (multi-ghp) system figure shows the room temperature when the indoor temperature is set to °c (± °c) in the summer. figure shows the room temperature when the indoor temperature is set to °c (± °c) in the winter. even if the set temperature of the room is only slightly out, the occupants are uncomfortable. the results of the simulations were verified in all cases setting a range of set temperatures of the room. for case - the summer room temperature is as follows: average room temperature is . °c, maximum temperature . °c and minimum temperature . °c. case - average room temperature % ∑ ∑ ( ) ∑ ( ) ∑ ( ) ( ) energies , is . °c, maximum temperature . °c and minimum temperature . °c. case - winter room temperature is as follows: average room temperature is . °c, maximum temperature . °c and minimum temperature . °c. case - average room temperature is . °c, maximum temperature . °c and minimum temperature . °c. in cases - and - , the multi-ghp system existing operation method and abs chiller-heater systems were separated. case - and - , applying the operation method of case of a high efficiency heat pump, are a combined method multi-ghp system and abs chiller-heater system. first of all, after the high efficiency multi-ghp systems are used, the abs chiller-heater systems are operated if the ghp only is not in charge of the load. as listed in table , the room temperature approached the set point more with cases - and - than with case , and the room temperature variation was reduced. accordingly, the indoor thermal environment control was comfortable and stable. (a) (b) figure . indoor environment conditions of the multi-ghp system in the summer: (a) existing operation condition of multi-ghp system (case - ); (b) sequencing operation condition of multi-ghp system (case - ). (a) (b) figure . indoor environment conditions of the multi-ghp system in the winter: (a) existing operation condition of multi-ghp system (case - ); (b) sequencing operation condition of multi-ghp system (case - ). energies , figure shows a graph of the multi-ghp system summer cold water inlet-outlet temperatures and coefficient of performance (cop) in each case. the maximum cop of case - appeared to be . . the multi-ghp system outlet temperature was approximately °c, and the inlet temperature was approximately °c. the wasted energy was consumed to meet the chilled water temperature of °c. in case - , which reflects the room load directly, the cop had a maximum of . . the multi-ghp system outlet water temperature was – °c. case - to case - showed better performance than the control method, which reflected the load directly, resulting in energy savings. figure shows a graph of the multi-ghp system winter hot inlet-outlet temperatures and cop in each case. the maximum cop of case - appeared to be . . the multi-ghp system outlet temperature was approximately °c, and the inlet temperature was approximately °c. the wasted energy was consumed to meet the chilled water temperature of °c. in case - , which reflects the room load directly, the cop had a maximum of . . the multi-ghp system outlet water temperature was – °c. case - to case - showed better performance than the control method, which reflected the load directly, resulting in energy savings. (a) (b) figure . coefficient of performance (cop) and summer cold water inlet-outlet temperatures for the multi-ghp system: (a) existing operation condition of multi-ghp system (case - ); (b) sequencing operation condition of multi-ghp system (case - ). (a) (b) figure . cop and winter hot water inlet-outlet temperatures for the multi-ghp system: (a) existing operation condition of multi-ghp system (case - ); (b) sequencing operation condition of multi-ghp system (case - ). energies , figure presents the results of comparative analysis of the multi-ghp system energy consumption by each case result. the total energy consumption of the existing operations was gj. in case - , which is the sequencing control according to room temperature, the total energy consumption was gj. the energy consumption of case - was reduced by approximately % compared to the existing method. case - showed the highest possible energy savings compared to most existing methods because it directly reflects the operation plan of the room load. a control method for case - , which can increase the efficiency of the multi-ghp system, uses hybrid operations, and the total system can save the energy of the multi-ghp system. a possible complex operation would be an efficient multi-ghp system load that improves and reduces the abs chiller-heater load and improves the energy efficiency. figure . comparison of the energy consumption for the multi-ghp system: case - : existing operation condition of the multi-ghp system; case - : sequencing operation condition of the multi-ghp system. . . . operation cases of a combination with the multi-geothermal heat pump (multi-ghp) systems and the absorption (abs) chiller-heater system table lists the simulation result of the multi-ghp system for each case. figure presents a performance and load relationship graph of the multi-ghp system coefficient in each case. the maximum cop of case - appears to be . . the existing operations of the target building were a separate and independent multi-ghp system and abs chiller-heater. in this way, all heat source systems will be operated, even if the load of the building satisfies only efficient multi-ghp system. as a result, energy wastage occurs. therefore, the case - system was combined with an existing heat source to enhance the efficiency of the multi-ghp system, and achieve an efficient multi-ghp system. in case - , which directly reflects the room load, the cop was a maximum of . . increasingly better performance in the case - to case - equipment was achieved using a control method that reflects the load directly. figure compares the energy consumption of the heat source equipment of cases - and - . the multi-ghp system energy use of case was reduced by % compared to case , and in the case of the abs chiller-heater, the energy consumption was reduced by %. in the existing method, although the outlet temperature of the multi-ghp system was fitted by approximately °c, the energy use of energies , the multi-ghp system was reduced. in addition, the improved efficiency by operating the multi-ghp systems reduced by the use of the abs chiller-heater. as a result, the total energy consumption of the heat source equipment was reduced by %. table . indoor environmental conditions for combination with the multi-ghp systems and the abs chiller-heater system. case room air temperature (°c) cop hp energy consumption (gj) total energy consumption (gj) case - . . . case - . . . figure . cop and load relationship graph of combination with the multi-ghp systems and the abs chiller-heater system: case - : existing operation condition of the multi-ghp system and abs chiller-heater system; case - : sequencing operation condition of the multi-ghp system and abs chiller-heater system. figure . comparison of the energy consumption for combination with the multi-ghp systems and the abs chiller-heater system. . . future research in progress in most buildings, the multi-ghp system is responsible for air conditioning the building part. in addition, the efficiency can decrease because the multi-ghp system and the existing heat source are energies , separate and operating independently. on the other hand, even if there is no load on the ahu served area, unnecessary energy is consumed to meet the chilled water set point temperature. this study developed as multi-ghp system control algorithm according to the load condition, which is not in accordance with a set point. on the other hand, as a hospital building is being used, the developed algorithm has a problem in that it cannot be applied immediately. therefore, a reliability validation and pre-simulation evaluation was conducted through short-term analysis. a simple comparison is difficult because the operating status of each building varies. accordingly, future studies focusing on the integration of the multi-ghp systems and abs chiller-heater will compensate for the proposed algorithm. complementary algorithms will be applied to building and long-term analysis will examine the effective use of the multi-ghp system. . conclusions in this study, after selecting a building containing the actual installed ghp, the use of excellent ghp systems was maximized in terms of the energy efficiency. the methods of complex operation regarding abs chiller-heater and ghp systems were proposed and evaluated through simulation: ( ) the multi-ghp system of building operates to match the setting to the load side return temperature. accordingly, on/off control was performed. on the other hand, no load area was used to fit the chilled water temperature at the set point. therefore, unnecessary energy was consumed highlighting the need for a control plan. ( ) in the case that the return temperature of the multi-ghp system is operated, energy wastage occurs regardless of the indoor load operation. therefore, the actual load that reflects the room temperature monitoring control is proposed. ( ) owing to the separation of the geothermal systems and heat source system, when the entire load is satisfied as a geothermal system, a waste of energy occurs in the operation. by incorporating the system, improved efficiency could be achieved by maximizing the multi-ghp system operation; hence, the minimum use of the heat source plan is proposed. as a result, the multi-ghp system energy use of hybrid operation condition of the multi-ghp systems and the abs chiller-heater system was reduced by % compared to the operation condition of the multi-ghp system and the total energy consumption of the heat source equipment was reduced by %. the results showed that the efficient operation of the multi-ghp system is possible. acknowledgments this study was supported by a grant ( ctap-c - ) from infrastructure and transportation technology promotion research program funded by ministry of land, infrastructure and transport of korean government. author contributions all authors contributed to this work. young-ju jung performed the result analysis of simulation and wrote the major part of this article. hyo-jun kim conducted the energy simulation. kyung-ju shin simulation data were summarized. jae-hun jo proposed the case of the energy simulation and energies , conducted data analysis. yong-shik kim performed the result discussion and gave technical support. young-hum cho was responsible for this article and gave conceptual advice. conflicts of interest the authors declare no conflict of interest. references . technical report for medium term oil market; international energy agency (iea): paris, france, . . healy, p.f.; ugursal, v.i. performance and economic feasibility of ground-source heat pumps in cold climate. int. j. energy res. , , – . . lienau, p.j. geothermal heat pump performance and utility programs in the united states. energy sources , , – . . phetteplace, g.; sullivan, w. performance of a hybrid ground-coupled heat pump system. ashrae trans. , , – . . hepbasli, 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. , i s s u e , international journal of innovative research in physics designing of eco-friendly water-run car shuvrakanti choudhury , nikesh kumar ,* mechanical engineering department, institute of engineering and management, kolkata email: nikesh.kumar@iemcal.com abstract this review paper highlights the use of water driven motor as an alternate energy source to conventional engines. water run motors can be efficiently utilised in vehicle. it will solve the problem of energy crisis as well as the pollution problem. brown’s gas is used to run such engine. the electrolysis procedure and hydrogen burning is the two main steps in the operation of such engines. limitations of such engines are also discussed. keywords: water fuel cell, electrolysis, hydrogen energy, eco-friendly . introduction the main issue with earth’s sustainability is going to be the increase in population and subsequently the increase of demand in energy resources. the fossil fuel will definitely fail to fulfil this increased demand in near future. this crisis of natural energy resources will also affect the transport medium and will lead to uncertain future. global warming is also accelerated due to the extensive use of such fossil fuel. so, it is the need of the time to look for alternative solution to these problems by using other sources of energy for running a vehicle. in this context, the concept of electrolysis can be utilized to have water run car. water (usually salted water) is broken into its component hydrogen and oxygen by the method of electrolysis and the generated hydrogen can be used to supply energy to the vehicle. since carbon is not involved in this process, it becomes more eco-friendly. development of water powered vehicle can be treated as one of the solution of the energy and environmental crisis. the water vehicle is based on the concept of converting water energy to the mechanical energy. the proposed design allows for fewer moving parts, which gives higher efficiency. this technique of water driven energy source can use as a passenger vehicle, as a load carrier. . description the water fuel cell splits water into its two component elements i.e. hydrogen and oxygen. the produced hydrogen gas in this process is then burned to generate required energy. devices run by this method require less energy for electrolysis compared to other predicted procedures. the mechanism involves “brown’s gas” which is a mixture of oxyhydrogen with a ratio of : . this motor device based on water is usually reversed for cells that generate electricity from a chemical red- ox reaction, in contrast this consumes electricity. by using this cell we generate sufficient energy which we can use for driving a car. we use this energy to substitute fuel. we separate the oxygen produced in the i s s n : - x ( p r i n t ) i s s n : - ( o n l i ne ) i j i i p , v o l . , i s s u e , international journal of innovative research in physics electrolysis process and by using silencer pipes we can release the oxygen gas in nature to make the car eco- friendly. as we know water is easily available so it will not be very costly for the people to use this kind of car. figure is a water fuel cell by using this we need minimum energy to perform the electrolysis. fig . electrolysis. figure is taken from wikipedia. fig . water fuel cell patent by stanley meyer. figure is taken from wikipedia. i s s n : - x ( p r i n t ) i s s n : - ( o n l i ne ) i j i i p , v o l . , i s s u e , international journal of innovative research in physics . results when we calculate the driving performance we have to account for vehicles, maximum speed, time to accelerate and more over one of the important factor is its grad ability. all these design parametric depends upon speed and power characteristics of the motor. the motor has a fixed power in the high speed region, which is higher than its base speed. measurement of performance of such motor is done by calculating speed ratio (x), which is defined as the ratio of maximum speed to the base speed of the motor. and the electronic control unit keeps the motor voltage constant and due to this the flux weakens and drops out in the shape of a hyperbola when the speed is increased after the base speed. and the torque also starts dropping down in the form of a parabola when speed is increased. water run car is a permanent solution to the problem of pollution. it is a solution to the problem of increasing of prices of petrol and diesel; hence it is cost-friendly. since water is all time available source so water-run car is a permanent solution to the problem of the resource crisis the world is facing now-a-days. . conclusion climate change is actually happening and this is just the beginning. carbon emission is on a constant rise and we are hardly doing anything about it. according to un’s report, in the next years, global greenhouse emission need to go half than what it is today. basically all the coal plants and petroleum fuel based vehicles on earth need to be replaced by zero carbon alternatives. if it is possible to make a water run car it will be very helpful for entire world. in this paper, the working of a water run energy source is discussed. the utilization of such source can be running a vehicle. the advantages over conventional sources are also discussed in terms of environmental benefit. in addition to this, the gears which were used for transmission of power from motor to the wheels were also analysed and the results were satisfactory. . limitation if we want to make this device hundred per cent efficient it will violate first and second laws of thermodynamics. so it can’t be fully efficient. . acknowledgement the authors would like to acknowledge the basic science and humanities department of institute of engineering and management for their constant support and advices towards the paper. the authors are also thankful to dr. koyel ganguly, prof. arnab basu for their unconditional help. references [ ] c.c. chan and k.t. chau, modern electric vehicle technology, oxford university press, new york, . [ ] k.m. rahman and m. ehsani, performance analysis of electric motor drives for electric and hybrid electric vehicleapplication, ieee power electronic in transportation, – , . [ ] y. gao, h. maghbelli, m. ehsani, et al., investigation of proper motor drive characteristics for military vehicle propulsion,society of automotive engineers (sae) journal, paper no. - - , warrendale, pa, . i s s n : - x ( p r i n t ) i s s n : - ( o n l i ne ) i j i i p , v o l . , i s s u e , international journal of innovative research in physics [ ] z. rahman. m. ehsani, and k. butler, an investigation of electric motor drive characteristics for ev and hev propulsionsystems, society of automotive engineers (sae) journal, paper no. – – , warrendale, pa, . [ ] z. rahman, m. ehsani, and k. butler, effect of extended-speed, constant-power operation of electric drives on the designand performance of ev-hev propulsion system, society of automotive engineers (sae) journal, paper no. – – , warrendale,pa, . [ ] d.a.j. rand, r. woods, and r.m. dell, batteries for electric vehicles, research studies press, ltd.,baldock, hertfordshire,united kingdom, . [ ] y. gao, h. maghbelli, m. ehsani, et al., investigation of proper motor drive characteristics for military vehicle propulsion,society of automotive engineers (sae) journal, paper no. - - , warrendale, pa, structuri organizatorice specifice Întreprinderii bazate pe cunoaŞtere annals of the „constantin brâncuşi” university of târgu jiu, economy series, issue / „academica brÂncuŞi” publisher, issn – /issn-l - epistemological argumentation of sustainable development and grenn energy maftei daniel postdoctoral resercher, institute of national economy, romanian academy, bucharest, romania email: danielmafthei@yahoo.com abstract: it is curios how the society is becoming more developed, but at the same time, increasingly ill, although it has a stock of so vast knowledge. in the last years this knowledge, combined with technology are increasingly directed more towards remedying environmental problems. however it seems that efforts are not enough. so when all these modern realities were still in their early stage, the scientific community has rung alarm bells that were first expressed terminology and then through practical plans of what we generic call today, sustainable development. the paper proposes an analysis of the issues of sustainable development and energy from epistemological and knowledge perspective of the various theories that directly or indirectly address these issues. keywords: sustainable development, green energy, epistemology, energy theories j.e.l. classification: f , p , q . . introduction awareness of rational exploitation of resources has increased lately even more, especially considering the obvious ecological crisis faced by the world, and on the strenght of alarm the alarm signal that pulled the energy crisis of the s. if we approach economically the resources we can discuss of two major types: first, the "natural wealth" as its many forms, from coal, gas, oil, nuclear power that have dominated the interest of the whole society throughout history. a second category of wealth has an unusual shape and was "discovered" at its true value much later - it is information that has now become very important. viewed through the prism of economic development, which has permanent need of energy, and which carrie indispensable of environment, of ecological systems, it is often named eco- development, the relative harmony between the environment and economic development. technical and scientific progress every day brings new ideas that are exchanged for new ways to new economic growth performance. they can make significant, even radical the natural environment in which takes place the economic activity. the irrational exploitation of nature began to take shape once with the energy crisis and the crisis of raw materials when it was found, for the first time, a chaotic use of natural resources with serious consequences for general and local ecological balance. recent decades increasingly reflecte better the old idea that man and nature walk on two different paths, we can say antagonistic, because each has its own set of rules for development. if talk of an environmental dimension in economic growth field, awareness of this part was done much later and had, inevitably, a number of causes. if talk of an environmental dimension in economic growth, awareness of this part was done much later and was inevitably a number of causes. the first one was the existence of misconceptions assign a role more important than financial resource type and the means by which it was obtained, wiping from analysis plan or minimizing the "quality" part of development of environment and ecosystems. secondly, it seems that public attention has not been drawn to such a subject, as long as other issues, considered more important, kept daily agenda - global variety development, wars and arming, poverty and hunger, etc. in the third place, in the framework of some economic theory was fueled the contradiction between the idea of economic development and the environment - until recently, when the attitude of several specialists seems to have evolved while making it a part of the antinomies of two concepts. but rhetorically we ask if their old theories were not supported by economic or political arguments. over time it was materialized numerous environmental concepts and they gaining a varied character. some of this draw attention with the theories in which they were handled, especially that they are clearly referring to environmental protection through the use of alternative resources and bring forward growth using alternative and clean energy sources that not affect the environment. annals of the „constantin brâncuşi” university of târgu jiu, economy series, issue / „academica brÂncuŞi” publisher, issn – /issn-l - . theories concerning the sustainable development and energy the first theory with reference to environmental protection is "ecocentric theory" which brings to the forefront the idea that the protection of earth is an aim in itself. the planet must be defended without any reservation, without any doubt. any brutal human intervention on tera resources is convicted and punished. therefore the planet must be preserved throughout of her future. consequently man takes a secondary role in such global equation, it is only one element among millions of other constituents of the planet. conservation of "global wealth" prevails. also, at this point, in our analysis we can mention the work "limits to growth" (aurelio peccei) developed [ ] following the request of the club of rome, which states that around the s, keeping a constant linear rate of growth , nonrenewable and traditional resources will be exhausted in most of them. but not only will be exhausted, but will leave behind their use an environment which starts to be increasingly hostile to man who used for a time these resources to produce energy, but which have to find new ideas to counter the effects, on the one hand, and to continue daily activities, on the other hand. the solution offered by this theory is intended to slow the economic growth, moreover, give it a downward trend. the conception still leaves open gates to adopting innovation to produce clean energy. the second conception is concerned especially of the other forms of life and of globally existing species, taking name of "biocentric conception." it is bound by its contents of ecocentric theory but also present some nuances. the analysis angle provides an overview of things that, generally, the animals can not defend themselves as a man does. the only attribute of the latter argument is to defend the diversity of flora and fauna. therefore we perceive that the theory lacks something: do not consider the man who has already reached a certain level of development, knowledge, and that these processes are effectively irreversible. only by contradiction, conceptual, scriptic, could be imagined such a way to build a global society. another weak spot of theory is the excessive conservatism that does not take into account the danger of existence of human being for the future. protection of animals, plants, like an argument against millions of hungry people and poverty can not stand. therefore the theory needs alternative to the raised issues, the solution to the energy production so indispensable to man. father of this theory, namely of biocentric theory [ ] is considered nicholas georgescu-roegen, with his base "the entropy law and the economic process" ( ). other prominent promoters of this conception are albert schweitzer, a doctor from alsace region in which gave organ concerts in europe to earn money to invest in maintaining a hospital in africa and for environmental projects. albert schweitzer was a theologian and philosopher. he received the nobel peace prize in . included are pierre techard of charoin, biologist who published between and three books with wide popular addressability "future of humanity" [ ] "man's place in nature [ ] "," human phenomenon [ ] ". the third concept is the "anthropocentric conception" on environmental conservation that contains the idea that everything is dependent on human needs - these needs are constantly growing and diversifying. however we can not generalize human importance as a factor which permitted any action in strengthening its own good - especially that at this point there is a very important nuance, namely: if the man knows which is his own good or not. do not induce momentary good the long-term harm? thus, any idea that the good of the individual moment is satisfied induce the opposite in the long term. the experience of the last century has shown that human development must take place within the limits imposed by nature - otherwise, it calls into question the existence of the human species. from theory we can extract the idea that the expansion of human interests can be achieved using nature as long as it does not affect his native balance - we may use the renewable resources, fueling our energy needs in an increasingly growing. among the promoters of this theory we can mention protagoras of abdera (~ bc) who said that "man is the measure of all things". continuing somewhat the same idea, the frenchman rené descartes called the man as "master of nature." they are contradicted today by the ecological practice showing that man is the only one who measured things and not the center of these measurements. we conclude on the concept that "can not accept the destruction of nature as a sacrifice on the altar of economic growth" as stated elcheveria l. alvarez, leading figure in the field of environmental protection. . ideologies related on sustainable development and energy at the same time, we can talk about a number of related ideologies that resides in the concepts above, involving the environment in various forms and including energy production. the first ideology is the abundance theory that brings in the frst plan the growth and development through resources, through their exploitation. in the markets they have a liberal character, without any restriction on the environment. when referring to a priority aim it is the maximization of gdp. markets therefore have the ability to adjust supply and demand eliminating any restriction in the lack of resources. ideology emphasizes the interests of the people who live now and almost never on the legacy of future generations; nature becomes a tool in the hands of exploiters. on the other hand, conciliatory ideology is at the other pole, and places particular emphasis on rational management of resources as well as conservation. also is assigned a new role for the economy - that of environmental protection through economic levers. economic growth is motivated only by careful choice of the means of production annals of the „constantin brâncuşi” university of târgu jiu, economy series, issue / „academica brÂncuŞi” publisher, issn – /issn-l - and consumption rate with direct effects on the environment. it excluded the idea of infinite durability. it promoted the idea of an active concern for others by bringing it to the forefront equity between people, and between generations. even if it promotes care for nature, it still retains the instrumental character. in terms of energy, not deny its importance; it accepte the idea of rational use, but the idea becomes more declarative than proactive. a third related ideology that lies the theories above is community theory. the premise from which we start is to save resources. from an economic perspective, it proposes to ensure a state of stagnation in both area, economic and demographics. collective interests are those that prevail over private interests and individual order. the value of goods receives a secondary role to the ecosystems that are at the forefront of vision. fourth ideology is the "radical". it goes towards conservation of the environment taken to the extreme, a total conservation of resources. [ ] thus, everything that means the environmental regulation is designed to be very strictly for the environmental impact to be very strict. in this vision is absolutely necessary a decrease in consumption and in economic growth. it promotes the so-called "bioethics" which conveys the idea of a morality that characterizes all planet species - nature becomes an intrinsic value and becomes totally independent of any human activity. all the concepts mentioned above can bring them together under a generic name of "reconciliation between man and nature [ ]," which seeks an approach of expanding human activity by reference to principles of general equilibrium of nature, providing a economic growth needed for humanity, and a reasonable framework for the recovery of the elements of nature. energy that we need, in light of all these considerations, must be given one of the determinants of "green", "organic," "sustainable," "renewable". [ ] . conclusions to see the advantages of green energy and bring new arguments to support it, we can not summarize a simplistic definition, but it requires synthesis through analysis. man uses energy in its various forms involving all economic activity, processing the raw materials taken from nature. objects used by each individual and results from the production process to meet the necessities of physiological, spiritual or social needs have as origin the only raw material that has been subjected to processing with energy aid. unfortunately, we can conclude that the way to produce energy is quite damaging, moreover, turns against man. the solution for the future is clear energy from renewable sources, confirmed by countless specialists. the problem occurs when the energy is not sure when the national and international market movements creates concerns. what strategy to apply? within which ideology we argue our actions? moreover, these states seem to intensify; studies, civil society, media, show a widening of resource issues, and the prices begin to rise to an unbearable limit to final consumers. the solutions are to identify problems, diagnose them correctly and acting knowingly through strengthening existing partnerships, creating new ones, creating energy research, environmental protection.the fact is that environmental resources are running out and the climate seems to change more and more - energy cost increases, international conflicts are intensified and affect the energy supplies. currently, but more so in the future, energy will become an economic and political blackmail actively supporting totalitarian regimes tint. although the two energy approaches of largest markets, the european union and the united states do not appear to have changed greatly in recent decades, environmental problems increasingly arising the government that is pressured to give a real start for green investments. the european union has done much more in this area by creating a coherent legal framework, but too bureaucratic. in times of crisis always resurface energy issues [ ]. from politicians to investors all make statements about such a subject, particularly statements about the oil market. this market is becoming increasingly difficult given the power transmission and prompt supply. at the same time access to energy is becoming increasingly complicated by the large emerging markets such as china and india where its absence would leave millions jobless employees who would remain poor with their families. acknowledgement this paper has been financially supported within the project entitled “horizon - doctoral and postdoctoral studies: promoting the national interest through excellence, competitiveness and responsibility in the field of romanian fundamental and applied scientific research”, contract number posdru/ / . /s/ . this project is co-financed by european social fund through sectoral operational programme for human resources development - . investing in people! annals of the „constantin brâncuşi” university of târgu jiu, economy series, issue / „academica brÂncuŞi” publisher, issn – /issn-l - bibliography . daduianu j., vasilescu i., environment and the economy, didactic and pedagogic publishing house, bucarest, . . donella h., meadows, h.d., randers, j., behrens, the limits of growth, london, . . georgescu-roegen n., the entropy law andthe economic process, harvard university press, . . maftei d., a., new approach for energy security – the efficient management of funds for investment in infrastructure for green energy, polish journal of management studies, poland, . maftei d., turbulences on the energy market? green solutions.studies in business and economics journal, sibiu, . martin l., poate exista securitate naţională într-o epocă nesigură?, encounter, . . peccei a., the limits of growth, council of europe, . . pohoață i., ce este dezvoltarea durabilă? punerea problemei, în "economistul" nr. , . pohoață i., dezvoltarea durabilă - concept multidimensional, în "economistul" nr. , . teilhard de chardin p. ,the phenomenon of man. new york, harper, . . teilhard de chardin p., la place de l'homme dans la nature; le groupe zoologique humain, union générale d'éditions, paris, . . teilhard de chardin p., the future of man. new york, harper & row, . hbrp publication page - . all rights reserved page research and applications of thermal engineering volume issue a novel development of vapor absorption air-conditioning system using engine exhaust heat j. siddhartha yadav *, ch. manikanteswar rao , n.s.c chaitanya raghu engineering college (a), visakhapatnam, india *corresponding author e-mail id:- siddharthayadav.j@raghuenggcollege.in abstract with the exponential rise in population, energy crisis has reached the pinnacle in the present scenario. hence, motivation to shift towards utilization of waste heat recovery has become a necessity now a days. this work deals with the development of single effect ammonia absorption air -conditioning system of . tr using waste heat from ic engine exhaust. the automobile exhaust waste heat is taken as source for generator heat input and the performance of the system was calculated. the system was run on a daily basis for hours and variation in the performance of the system was plotted. the exhaust system was developed by using an exhaust pipe of an automobile where the heat was supplied through gas cylinder .initially the maximum temperatures generated in an actual engine were calculated and based on those calculations the model was heated up to that temperatures and the system was made to run on trial. when the system produced us with the desired effect the performance was calculated and the variation in performance was plotted. hence, here an aim is made towards the development of sustainable energy model air-conditioning system where the dual advantage of reduced energy consumption and ozone depleting refrigerants are avoided. if properly implemented this research would provide a breakthrough in the field of waste heat utilization and development of energy-controlled usage of air conditioning systems. keywords:-ammonia, absorption system, waste heat, . tr, air- conditioner. introduction the two main sensational topics in the present-day world are the energy crisis and global warming. researchers are having tough time finding a solution for these problems. hence, this work deals with the development of a vapour absorption air conditioning system using exhaust heat of an ic engine as the source for input. waste heat utilization is becoming a necessity day by day due to the demand in energy consumption posed by the global population and the near extinction of fossil fuels. concentration on the same concept is done in this work where utilizing the waste heat generated in an automobile engine is used as the heat energy for generating the desired refrigerating effect. as it is a well known fact that vapor absorption system uses the heat energy to separate the refrigerant and the absorbent which causes the cooling effect to be generated hence it is aimed to develop the system by utilising the heat generated in an exhaust system of a stroke i.c.engine. as the entire heat released is directly emitted into the atmosphere so if we regulate this heat into a proper direction such as a vapor absorption system miraculous results can be expected in the near future. hence generation of an air conditioning system with the exhaust waste heat is the novel concept in this work. hbrp publication page - . all rights reserved page research and applications of thermal engineering volume issue literature survey michael papapetroua et al[ ] found a way to utilize waste heat of engine exhaust from automobiles in generating refrigerating effect. kajal sarmah, pushpendra gupta[ ] in their paper studied about the analysis of lithium bromide, water vapor absorption refrigeration system using the mole concentration concept. pongsidsrikhirin et al[ ] studied about the various vapor absorption refrigeration systems present and the working fluids which may be used to get various outputs. arturo gonzález gilstudied[ ] about solar air cooling on single & double effect lithium bromide vapor absorption refrigeration system. benjamin bronsema[ ] identified the problems faced in hybrid ventilation systems and provided certain solutions to them. t. o. ahmadu[ ] studied about a lithium bromide chiller, which gave a maximum c.o.p of . .the source utilized was waste heat in this experiment. mr. aniket gandhi & dr. r. r.arakerimath[ ] studied about solar vapour absorption cooling system utilizing parabolic solar dish collector where the c.o.p was obtained to be . for the cycle. joydeepchakraborty et al[ ] studied about lithium bromide vapor absorption system using solar energy. anan pongtornkulpanich [ ] studied about a new pair of absorbent and refrigerant in vapour absorption system using activated carbon and methanol providing the required heat through solar energy. sohail bux a.c.tiwari[ ] studied about designing a lithium bromide vapor absorption refrigerator providing the design conditions necessary for the heat exchangers. the literature survey states that most of the works related to vapor absorption system is done related to development of refrigerator very few works related to development of vapor absorption air conditioning system is done hence this work is in this direction for development of an ammonia water vapor absorption air conditioning system. experimental set-up the experimental set up consists of a vapor absorption air conditioning system. the input energy is taken from the exhaust of an automobile engine. the exhaust pipe is wound with copper coil which acts as the generator where the heat is absorbed and the separation of refrigerant absorbent takes place. after passing through the generator it enters the absorber and the refrigerant enters the condenser. from the condenser the refrigerant passes into an expansion valve where it gets expanded and the pressure reduction takes place. next, it enters the evaporator and allows the cool air to pass into the cooling space giving the required desired effect. from the evaporator the refrigerant passes into the absorber where it again mixes with the absorbent forming a solution. this solution is pumped into the generator which raises the pressure of the solution as it enters the generator. in this way a cyclic process is developed generating the necessary refrigerating effect. hbrp publication page - . all rights reserved page research and applications of thermal engineering volume issue fig. :-cyclic representation of vapor absorption air-conditioning system results & discussions table :-values representing the c.o.p for days along with the corresponding evaporator, condenser & generator temperatures. sl. no evaporator temperature in k (te) condenser temperature in k (tc) generator temperature in k (tg) c.o. p day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . hbrp publication page - . all rights reserved page research and applications of thermal engineering volume issue fig. :-representing the plot between the c.o.p vs day for days respectively. conclusion % of power consumption among electrical equipment is due to the air conditioners used in our household. hence this work aims at solving this problem by using the waste heat technology to generate a vapor absorption system to develop the required refrigerating effect for a . tr air conditioner. although some amount of power is used in operating the pump, the fans utilised in the condensers and evaporator the power consumed by this is many times lesser than the power consumed in a vapor compression system. although a compromise has been made with the maximum cop developed in this system for its counterpart of a vapor compression system which boasts of around . . it is generated at a cost of % greater than this vapor absorption system. hence this work poses of providing a solution to the most important and burning problem of reduction in global warming by using reduced power in its system, eradication of ozone depletion layer as the refrigerant used is ozone friendly. although it is a small step towards providing a solution to giant problems of global warming and utilising unharmful refrigerants further designing and development of an improved cop will definitely create a lot of buss on such works in near future which is the proposed future work. references . papapetrou, m., kosmadakis, g., cipollina, a., la commare, u., & micale, g. ( ). industrial waste heat: estimation of the technically available resource in the eu per industrial sector, temperature level and country. applied thermal engineering, , - . . sarmah, k., gupta, p. ( ). refrigeration by waste heat recovery. international journal of interdisciplinary research. ( ). . walawade, s. c., barve, b. r., & kulkarni, p. r. ( ). design and development of waste heat recovery system for domestic refrigerator. iosr journal of mechanical and civil engineering, issn, - . . rai, n. kaushik, p, hitesh, p. design and analysis of ac system for automobile vehicle using exhaust heat. . złoty, Ł., Łapka, p., & furmański, p. ( ). analysis of cooling of the exhaust system in a small airplane by applying the ejector effect. journal of . . . c.o.p hbrp publication page - . all rights reserved page research and applications of thermal engineering volume issue power technologies, ( ), - . . lokhande, s. b., & barve, s. b. ( ). design &analysis of waste heat recovery system for domestic refrigerator. international journal of modern engineering research, issn, - . . balaji, k., & kumar, r. s. ( ). study of vapour absorption system using waste heat in sugar industry. iosr journal of engineering, ( ), - . . singh, r. k., ahmad, s. n., priyadarshi, n., rahman, m. o., & bhoi, a. k. ( , august). waste heat energy utilization in refrigeration and air-conditioning. in iop conference series: materials science and engineering (vol. , no. , p. ). iop publishing. . fricke, b. a. ( ). waste heat recapture from supermarket refrigeration systems (no. ornl/tm- / ). oak ridge national lab.(ornl), oak ridge, tn (united states); building technologies research and integration center. . bux, s., & tiwari, a. c. ( ). eco friendly automobile air- conditioning utilizationexhaust gas waste heat of internal combustion engine. international journal of mechanical engineering and technology (ijmet), ( ), - . mysterious anti-gravity and dark-essence january , : wspc/ -mpla s x – modern physics letters a vol. , no. ( ) ( pages) c© world scientific publishing company doi: . /s x mysterious anti-gravity and dark-essence je-an gu leung center for cosmology and particle astrophysics, national taiwan university, taipei , taiwan jagu@ntu.edu.tw received may accepted october published january the need of anti-gravity and dark-essence in cosmology is the greatest scientific mys- tery in the st century. this paper presents a personal view of several relevant issues, including the long-standing cosmological constant problem, the newly emerging dark radiation issue, and the basic stability issue of the general-relativity limit in modified gravity. keywords: dark energy; modified gravity; dark radiation; cosmological constant prob- lem. . introduction cosmology is a science of the evolution, the structures and the compositions of the universe. it has recently become an experimental science driven by astrophys- ical observations. in addition to observations, describing and understanding our universe require an initial condition of the universe and a theory of fundamen- tal fields/particles and interactions, such as general relativity for gravity and the standard model of particle physics for the others. the modern version of the cosmic story told by observations is interesting and surprising. it involves the following unexpected characters. • special initial condition. the cosmic background was rather flat, homogeneous and isotropic; the primordial perturbations were rather adiabatic, scale invariant and gaussian. the inflation scenario is doing a great job in giving such initial condition. • extra gravity. the extra attractive gravity is needed to help the cosmic struc- ture formation. a favorite scenario of extra gravity is invoking dark matter. • anti-gravity. the repulsive gravity is needed to drive the accelerating expansion of the present universe. it invites the consideration of the energy source of anti- gravity dubbed “dark energy” and gives strong motivation for modifying gravity. - m od . p hy s. l et t. a . . d ow nl oa de d fr om w w w .w or ld sc ie nt if ic .c om by n a t io n a l t a iw a n u n iv e r s it y o n / / . f or p er so na l us e on ly . http://dx.doi.org/ . /s x mailto:jagu@ntu.edu.tw january , : wspc/ -mpla s x – j.-a. gu in the scenario with dark matter and dark energy, the two unknown dark com- ponents contribute % of the energy of the present universe, presenting us the greatest enigma in fundamental science at all times. anti-gravity is particularly mysterious. it may be caused by dark energy or modified gravity. the simplest candidate of dark energy is a positive cosmological constant. it was firstly introduced by einstein and later abandoned as his biggest blunder. it is so far so consistent with the observational results and therefore has been widely considered. nevertheless, the smallness of the cosmological constant and the coincidence problem (why the cosmic expansion just starts to accelerate recently or why the present matter and dark energy densities are comparable) in this model require fine-tuning and make this model look unnatural. the fine-tuning stems from the constant nature of the cosmological constant. to avoid the fine- tuning, a necessary condition is the time variation of the dark energy density. this invites the consideration of a scalar field as a simple phenomenological realization of dark energy with a time-varying energy density. as to modified gravity, although there is no evidence of such modification, the above three surprising characters give strong motivation for modifying gravity. al- though general relativity (gr) so far can pass all the local tests, it is still open for the cosmological tests. as an essential requirement from the success of gr in passing the local tests, in any viable modified gravity model the gr limit must exist and be stable, not just at the action level, but particularly at the solution level. in addition to dark matter and dark energy, the recent cosmic microwave back- ground (cmb) observations suggest one more dark component called “dark radia- tion” that represents the additional relativistic degree(s) of freedom. it is expected to give important effects in cmb and in big-bang nucleosynthesis (bbn). the remainder of this paper will provide a simple personal view of three relevant issues: the cosmological constant problem, dark radiation, and the stability of the gr limit in modified gravity. . cosmological constant problem observations have given an upper bound to the energy density of a cosmological constant: ρΛ . × − ev , i.e. its energy scale . − ev. this upper bound is much smaller than the expected contribution from the quantum vacuum, leading to the long-standing, notorious cosmological constant problem. in the framework of quantum field theory the vacuum energy can contribute to dark energy of the same form as a cosmological constant. its size may be designated by the high-energy cut-off scale of the quantum field theory that, either the planck scale, the electroweak scale or some other scale involved in the standard model of particle physics, is much larger than − ev. one may think this problem unrealistic because the physics, particularly that of gravity, around the cut-off scale is not well tested and the correct way of assessing the gravitational effect of the - m od . p hy s. l et t. a . . d ow nl oa de d fr om w w w .w or ld sc ie nt if ic .c om by n a t io n a l t a iw a n u n iv e r s it y o n / / . f or p er so na l us e on ly . january , : wspc/ -mpla s x – mysterious anti-gravity and dark-essence vacuum energy around the cut-off scale is not clear. let us put aside the unclear high-energy cut-off scale and consider the low-energy scales such as the ev scale, i.e. the micron length scale. even the quantum fluctuations of the ev scale can provide too large vacuum energy and ruin our universe, while the physics at such scale is well known and has been tested thoroughly. that tells the genuineness and the severeness of the cosmological constant problem. one naive way of surviving the vacuum energy crisis is to compensate the vac- uum energy with a bare cosmological constant that might be introduced at the very beginning of the universe. the size of the bare cosmological constant needs to be delicately chosen to balance the vacuum energy of quantum fields. another naive way is to make the vacuum energies of different quantum fields cancel each other via carefully choosing the field contents and finely tuning the very details of the field theory. these two naive ways are so fine-tuning that one can hardly believe they can be a part of the grand design in nature. even if such fine-tuning is invoked at the beginning of the universe, the later phase transition(s) associated with spontaneous symmetry breaking (ssb), such as the electroweak phase transition, would ruin the initial fine-tuning. during a ssb phase transition, the vacuum energy may drop by an amount on the energy scale of the phase transition (e.g. ∼ mev for the electroweak phase transition), thereby ruining the perfect cancellation in the initial design. if one insists to invoke the brute-force cancellation, the design would be as tedious as the following sentence: it is necessary to foresee all possible ssb phase transitions and know the very details of the vacuum energy change during each of them, as detailed as − ev at least, and then make the earlier cancellation imperfect, with the energy deficit on the scale of the phase transition and with the precision − ev or better. a good job of solving the vacuum energy crisis should not be as tedious as the brute-force cancellation. a satisfactory solution to the cosmological constant problem is yet to be found and the appropriate scenario for the solution is also not yet clear. the final solution may be associated with the reconciliation between gravity and quantum, while such ultimate paradigm is still in the mist. . dark radiation dark radiation is the additional relativistic degree(s) of freedom suggested by the recent cmb observations. it may be the only surprise so far in the st century in cosmology. in the th century there were several salient surprises in cosmology, such as the cosmic acceleration, dark energy, dark matter, etc. in contrast, in the st century the Λcdm model fits the observational results so far so well, except the observational indication of dark radiation. conventionally cosmologists invoke the following fitting formula of the radiation energy density to fit data. ρrad = [ + ( ) / neff ] ργ . ( ) - m od . p hy s. l et t. a . . d ow nl oa de d fr om w w w .w or ld sc ie nt if ic .c om by n a t io n a l t a iw a n u n iv e r s it y o n / / . f or p er so na l us e on ly . january , : wspc/ -mpla s x – j.-a. gu here neff can be regarded as the effective number of the neutrino species, i.e. the number of the degrees of freedom of the relativistic neutrino-like parti- cles (weakly interacting or even non-interacting fermions), or, phenomenologically, it parametrizes the energy density of the relativistic degrees of freedom additional to the cmb photons. radiation is important in the early universe. with different amount of radiation, i.e. with different neff, the early universe has different looks, particularly regarding the cmb spectra and the bbn prediction of the light element abundance such as the he abundance. accordingly, the cmb and the bbn-related observations can give essential constraints on neff. in the standard model of particle physics the contribution from neutrinos to neff is close to . in contrast, the recent cmb observations, together with the ob- servations of large-scale structures and the measurements of the hubble parameter, suggest or more degrees of freedom, i.e. neff = – , and the standard model value is σ away from the best fit (see refs. – ). as to bbn, the bbn theory with neff = – is consistent with the observational results of the light element abundance (see ref. ). in the future the planck observation of cmb is expected to give more precise information about neff with the precision δneff ≃ . . thus, in addition to dark matter and dark energy that contribute % of the energy density of the present universe, we may need to invoke one more dark component, dark radiation, that changes the early-time expansion history, thereby helping to explain the cmb and bbn data related to the early universe. although dark radiation and dark energy provide very different functions, they provide the functions at two different epochs: one modifies the early-time expansion history and the other drives the late-time acceleration. therefore, it is possible to com- bine them, i.e. with one single energy source that behaves like dark radiation at early times and like dark energy at late times. in this scenario the dark en- ergy information may also be encoded in the early-time events such as cmb and bbn, in addition to the late-time events such as type ia supernovae and struc- ture formation. this distinct feature makes this possibility particularly worthy of further investigations. . stability of the gr limit in modified gravity since gr passes all the local tests, a viable model of modified gravity should behave very similar to gr at the local scales, particularly in the solar system. in addition, since the standard cosmology based on gr fits the observational results about cmb and bbn so far so well, people expect a viable modified gravity model should mimic gr at the early times relevant to cmb and bbn. thus, the gr limit should exist and should be stable in modified gravity at the local scales and at the early times. people may explore the existence of the gr limit at the action level. however, this is not good enough. the more essential is the existence and the stability at the solution level, because it is the solution but not the action that directly describes our universe. around the gr limit people may treat gr as a good approximation - m od . p hy s. l et t. a . . d ow nl oa de d fr om w w w .w or ld sc ie nt if ic .c om by n a t io n a l t a iw a n u n iv e r s it y o n / / . f or p er so na l us e on ly . january , : wspc/ -mpla s x – mysterious anti-gravity and dark-essence of the modified gravity theory. nevertheless, this may not be true when the gr limit is not stable. this issue is particularly serious in the modified gravity theories with higher- order derivatives such as the f(r) theory. the gravitational field equations of such theories are higher-order (higher than ) differential equations while the ein- stein equations in gr are nd-order differential equations. in this case, using gr to approximate modified gravity is to utilize the nd-order differential equations to approximate the higher-order differential equations, the validity of which is doubtful. in this approximation a significant portion of the solution space is abandoned, and the remaining solution space is approximated by another simplified solution space. to verify the validity of this approximation, people need to show that the abandoned solution space is not important and the simplified solution space is truly a good approximation of the remaining solution space. unfortunately this is not always true. in many cases the abandoned solution space is not negligible but may play an important role, and the simplified solution space as an approximation may be no good in a long run. that is, even if at the beginning the real solution is in the neighborhood of the simplified solution space, later it may leave away from the simplified solution space and even go deeply into the abandoned solution space. (for more details and for a heuristic demonstration of this issue, see ref. .) thus, in addition to the existence, the stability of the gr limit at the solution level needs to be carefully examined for any modified gravity model to be viable. . summary anti-gravity and dark-essences of the universe have been strongly suggested by astrophysical observations. they are the most mysterious in physics and cosmology. their nature and origin are the most important unsolved puzzles in the st century. this paper presents a simple personal view of several relevant issues, particularly the cosmological constant problem, dark radiation, and the gr limit of modified gravity. the cosmological constant problem may guide us to the final reconciliation between gravity and quantum. dark radiation may be the early-time manifestation of dark energy, with which the nature of dark radiation indicated by the cmb and bbn observations can provide important information about dark energy. as to modified gravity, the need of anti-gravity in cosmology gives a strong motivation and the cosmological observations provide important tests. in addition to performing the tests, the even more essential is to examine not only the existence of the gr limit at the action level but also its stability at the solution level. the clarification of these issues may help to solve the puzzle about the need of anti-gravity and dark-essences in cosmology. hopefully the solution to this great puzzle will lead us to a new revolution in physics in the st century and bring us an unprecedentedly complete picture of our universe. - m od . p hy s. l et t. a . . d ow nl oa de d fr om w w w .w or ld sc ie nt if ic .c om by n a t io n a l t a iw a n u n iv e r s it y o n / / . f or p er so na l us e on ly . january , : wspc/ -mpla s x – j.-a. gu acknowledgments we thank the dark energy working group of the leung center for cosmology and particle astrophysics (lecospa) at the national taiwan university for the helpful discussions. we thank the national center for theoretical sciences in taiwan for the support. gu is supported by the taiwan national science council (nsc) under project no. nsc - -m- - -my . references . j.-a. gu, dark energy crisis, nucl. phys. a , c ( ). . wmap collab. (e. komatsu et al.), seven-year wilkinson microwave anisotropy probe (wmap) observations: cosmological interpretation, astrophys. j. suppl. , ( ) [arxiv: . [astro-ph.co]]. . j. dunkley, r. hlozek, j. sievers, v. acquaviva, p. a. r. ade, p. aguirre, m. amiri and j. w. appel et al., the atacama cosmology telescope: cosmological parameters from the power spectra, astrophys. j. , ( ) [arxiv: . [astro-ph.co]]. . m. archidiacono, e. calabrese and a. melchiorri, the case for dark radiation, phys. rev. d , ( ) [arxiv: . [astro-ph.co]]. . y. i. izotov and t. x. thuan, the primordial abundance of he: evidence for non- standard big bang nucleosynthesis, astrophys. j. , l ( ) [arxiv: . [astro-ph.co]]. . j.-a. gu, can f(r) gravity mimic general relativity? int. j. mod. phys. conf. ser. , ( ). - m od . p hy s. l et t. a . . d ow nl oa de d fr om w w w .w or ld sc ie nt if ic .c om by n a t io n a l t a iw a n u n iv e r s it y o n / / . f or p er so na l us e on ly . http://www.worldscientific.com/action/showlinks?crossref= . % fphysrevd. . &ads= phrvd.. l a&isi= http://www.worldscientific.com/action/showlinks?crossref= . % fj.nuclphysa. . . &ads= nupha. .. g&isi= http://www.worldscientific.com/action/showlinks?crossref= . % f - % f % f % fl &ads= apj... l.. i&isi= http://www.worldscientific.com/action/showlinks?system= . % fs &ads= ijmps.. ... g http://www.worldscientific.com/action/showlinks?crossref= . % f - x% f % f % f &ads= apj... ... d&isi= the role of building thermal simulation for energy efficient building design energy procedia ( ) – - © the authors. published by elsevier ltd. selection and peer-review under responsibility of the scientifi c committee of indonesia ebtke conex doi: . /j.egypro. . . sciencedirect conference and exhibition indonesia renewable energy & energy conservation [indonesia ebtke conex ] the role of building thermal simulation for energy efficient building design rahmi andarinia,* aenergy efficiency and conservation clearing house indonesia, directorate general new renewable energy and energy conservation, ministry of energy and mineral resources, annex building th floor, jl. h.r. rasuna said x- , kav. – , jakarta , indonesia abstract in this paper, the results of building thermal simulation of office buildings in jakarta, indonesia are presented using the simulation and visualization tool of designbuilder, an energy plus based dynamic thermal simulation engine. the simulation results show that for new office design, building envelope optimization and utilizing high efficiency office equipment and hvac system, the annual energy consumption decreased by %. for the renovated building, implementing task lighting will reduce the energy consumption by %. in addition, applying task lighting with scenario improving glazing material with increasing chiller’s efficiency will give additional potential reduction of %. © the authors. published by elsevier ltd. selection and peer-review under responsibility of the scientific committee of indonesia ebtke conex . keywords : office buildings; building thermal simulation; energy consumption; new building; renovated building nomenclature ahu air handling unit ach air change per hour cop coefficient of performance hvac heating ventilating and air conditioning shgc solar heat gain coefficient * corresponding author. tel.: + e-mail address: rahmi.andarini@gmail.com available online at www.sciencedirect.com © the authors. published by elsevier ltd. selection and peer-review under responsibility of the scientific committee of indonesia ebtke conex rahmi andarini / energy procedia ( ) – . introduction the energy crisis is one of the world’s major current issues. in indonesia, the energy crisis creates a significant impact on economic development. therefore, the government has to set the saving energy as a major priority. further, energy saving must be in line with the efficient use of energy to have a positive influence to the environment, such as reducing ghg emission. using energy efficiently means reducing the fossil fuel being burned and therefore decreases greenhouse gas emission. high growth of population and economic rates in indonesia lead to the fast growing of cities. in a context where cities are booming, energy demand for buildings become a crucial problem, as there is huge construction activity in indonesia. in addition, the government regularly increases the electricity price as a result of the high price of world’s energy, consequently government also reducing subsidy in the energy sector. obviously, this increases the operational costs of a building, especially office buildings. in this paper, the solution to reduce the energy consumption in a high rise office building by integrating the thermal building simulations during the design phase of a building as well as for renovation project is presented. . methods . . designbuilder designbuilder coupled with the software tool energyplus is a powerful tool for modelling three-dimensionally building geometries as well as assessing the energy performance. there are also cad links into the d modeller as well as report generation facilities. designbuilder combines rapid building modelling with state of the art dynamic energy simulation [ ]. . . weather data weather data is an essential variable required in thermal building simulation that is unique and depending on the location of the building. the climate data used in this simulation is based on the weather data of jakarta, indonesia. which is located at western part of java island, at . ° south latitude and . ° longitude. the weather data for the building thermal simulation is generated by meteonorm . [ ]. - - - - hour [°c] w a tt s outside dry-bulb temperature °c relative humidity % direct normal solar w diffuse horizontal solar w [%] fig. . weather data of jakarta [ ]. . . reference base case of new office building the new office building simulated consists of floors, with total gross floor area of , m and conditioned area of , m . the building oriented to the north and south, and the building envelopes are dominated by glass rahmi andarini / energy procedia ( ) – facade. as a consequence, there will be potential solar radiation transferred into the building. therefore, recommendation on high performance glazing is very essential in a context the building is dominated by glass facade. fig. shows the visualization of the building designed using designbuilder. fig. . visualization of the building. table shows the parameter setting for reference base case building. the reference base case building means that the parameter was set to represent the operational condition that refers to available indonesian national standard (sni). table . parameter setting for reference base case building. parameter value unit wall u value . w/m k glass shgc value % glass light transmission . % office equipment power density w/m lighting power density w/m hvac cop . no unit lighting level lux infiltration . ach rahmi andarini / energy procedia ( ) – . . optimized design in the design process, the first recommendation suggested is by improving the building’s envelope. as previously explained, the building’s facade are dominated by glass facade, hence by improving the building’s facade there will be benefit in reducing energy consumption especially for air conditioning system. fig. . sensitivity analysis of glazing material. the scenario applied for sensitivity analysis is by installing better property of glazing material in order to obtain the glass specification that contributes to lower solar heat radiation transmitted into the building. in this scenario, glazing material with low shgc value was chosen. shgc value is a coefficient that represents energy (solar radiation, heat dissipated from inner glazing) transmitted by a certain type of glazing material. the value range from to , of which a lower value representing less energy transmitted, consequently there will be less solar energy entering the building. generally, low shgc value of glazing material will also influence its light transmission value. it can be seen that with the same glazing material, the double glass gives lower heat gain transmitted into the building than laminate glass. therefore, the recommendation for glazing material with regards to its property to transfer heat is using double glass. the represent daylight distribution as an effect of installing different type of glazing material is shown in fig. with the limitation of lighting level of lux as recommended by sni. it can be suggested that the consideration of using low shgc value and high light transmission is essential. fig. . daylight distribution for respective type of glazing material. rahmi andarini / energy procedia ( ) – . . reference base case of renovated office building the simulated building is built and operated since , consists of floors including basement floors. during the site survey in , the building is still not fully occupied. as the building has already been not operated for a couple of years, therefore it requires some site observations in order to obtain the actual conditions that require renovation in order to be ready to be occupied properly. fig. . the visualization of renovated building. based on the site survey, there are some opportunities may be applied to provide better performance the building envelope, which consist of: replacing the clear glass in existing building with reflective glass or low solar transmittance glazing material to reduce heat transmitted. installing shading device for window which intend to reduce the direct solar radiation. it is also possible to get additional advantage by utilizing shading device as light selves device at the same time. replacing the material of floor to reduce the effect of heat absorption. it is suggested that floor with carpet will reduce not only building’s cooling load, but also for noise reduction. additionally, for hvac system, the recommendations include ; conduct online measurement to test overall chillers condition; check performance of ahus; replace the old control valve of ahu; house keeping and maintenance. according to the building survey results for the lighting system sector, some preliminary recommendations are identified with the purpose to improve lighting level quality while at the same time, reducing overall energy consumption, such as: rearrange lighting zone, considering some areas that have been exposed to sunlight, therefore, it is necessary to rearrange the zoning of lighting. houskeeping control on lighting, the easiest way to saving energy with no additional cost required is to do reschedule the housekeeping, especially to control the lamp operating hours in the rooms that is unoccupied. replacing the old lamp shades with high efficient fixture/reflector replacing magnetic ballast with electronic ballast. magnetic ballast uses approx. - watt while electronic ballast uses only - watt. a tl hence, the electronic ballast will reduce electricity consumption by - %. replacing tlt – watts lamps with tlt – watt lamps. the collection of data gathered from building survey then considered as input parameter for building thermal simulation. other data that was applied is data provided by the appointed planning consultant, such as building’s drawing. in the case of unavailability of actual data, some assumptions were made as basic approach. rahmi andarini / energy procedia ( ) – . results and discussion . . building thermal simulation of new office building the simulation result for the reference base case of the building is graphed in fig. . it depicts the energy balance of the reference building. fig. . energy balance of reference base case new office building. heat gain means the heat transferred into the building from the environment as well as heat generated by entity in the building. heat loss is considered as heat transferred out of the building as an effect of lower outside air temperature, or works created with the purpose of removing heat from the building to the environment. the sensible cooling energy demand is categorized as heat loss because it works to remove heat in the building to the environment in such a way, so that the indoor air temperature of the building will satisfy its setpoint. in this reference base case, it is found that the high portion of cooling energy demand is mainly devoted to compensate the heat gain transmitted through the building envelope as well as generated inside the building. for the optimized building design, the scenario applied for sensitivity analysis is by implementing better configuration of building envelope by reducing the area of glass facade is reduced by raising the height of window stool in order to reduce solar radiation transmitted into the building. additionally, the setting parameter for optimized building will result to better energy performance of the building. the accumulation of electricity reduction is accounted that the reduction of electricity consumption index in kwh/m /year is about %. table . parameter setting for optimized new office building. parameter value unit wall u value . w/m k glass shgc value % glass light transmission . % office equipment power density w/m lighting power density w/m hvac cop . no unit lighting level lux infiltration . ach rahmi andarini / energy procedia ( ) – . . building thermal simulation of renovated building shadow analysis was performed in order to obtain the general knowledge on how the building exposed to the solar radiation. in january, while the sun position on the southern hemisphere, during the morning and afternoon hours the south side will be exposed to the solar radiation as shown in fig. . in july, the northern part of the building will be highly exposed to the solar radiation as shown in fig. . form this analysis, it is recommended that in order to minimize solar transmission, either by reducing the window area or by reducing solar transmittance coefficient. fig. . shadow position for january th . fig. . shadow position for july th . other possible alternative to reduce solar radiation is by reducing the shgc for the glass material. by applying lower shgc value of glazing material, the hourly solar heat gain transferred into the building drops dramatically, on average % of the reference base case. on the other hand, as lower shgc value normally followed by lower light transmission value, as the results, there is also significant increase of lighting energy required of the building. therefore, installation of task lighting is very important in order to optimize the use of additional artificial lighting. fig. . comparison solar heat gain as an effect of better glazing material. rahmi andarini / energy procedia ( ) – from the simulation, it is found that using task lighting will reduce the total electricity consumption by %. this reduction is contributed by the decrease of chiller’s electricity consumption by % and lighting’s electricity consumption by %. the significant decrease of lighting’s electricity consumption due to less lighting device operated as well as less power delivered for operational. the scenario of increasing the chiller’s efficiency aims to obtain the influence of chiller efficiency to the energy consumption of the building. the reference base case considered that the chiller efficiency was of cop . . this value was used as an assumption that the chiller’s age is already years old, and the consideration of annual efficiency reduction. in this scenario it was set that the chiller is assumed at its newest condition or as written on its technical data specification, that is of cop . . the simulation result shows that by improving chiller’s efficiency will influence significantly to the reduction of electricity consumption. fig. elucidated that electricity consumption of chiller with higher efficincy essentially decrease approximately by %. fig. . comparison of chiller’s electricity consumption as an effect of better chiller’s efficiency. observation on indoor air setpoint temperature however is not part of renovation project. it is more focusing on the operational concern. the simulation on the variation of the comfort temperature has been done by changing the indoor air set point temperature. the set point temperature means the temperature at which the cooling device will operate when the indoor air temperature is above this value. the initial value of the temperature set point was °c, which is suggested by sni. the scenario was made by decreasing the indoor air setpoint temprature by oc, or become oc. the simulation result shows that chiller will consume more energy when the indoor air setpoint temperature is lower. it is accounted that the increase of energy consumption is %. fig. . comparison of chiller’s electricity consumption as an effect of decreasing indoor air setpoint temperature. rahmi andarini / energy procedia ( ) – the following figure shows the comparison of electricity consumption for all simulation scenarios in percentage. the reference base case is represented in % of electricity consumption. fig. . comparison of electricity consumption for simulation scenarios. the results of thermal simulation and cooling energy sensitivity analysis shows that the application of better glazing material property gives substantial impact to the reduction of cooling load. compared to the application of shading device, better characteristic of glazing material gives more essential reduction of solar heat gain. negatively, the lower the solar transmittance value is normally followed by lower light transmittance. consequently, the lighting load of lower transmittance glazing will increase. as lighting contributes only % of the total energy consumption, therefore the increase of % is still acceptable. in addition, by improving chiller’s efficiency will reduce significantly the electricity consumption of chiller. the more important aspect other than renovation point to be considered concerning energy consumption is the indoor air setpoint temperature. it is found that by decreasing the temperature by oc will cause the increase of cooling load and corresponding chiller electricity by %. this value is obviously essential as chiller distributes % of the total electricity consumption. by improving the building design, it is found that glazing material gives significant impact to the reduction of cooling load, and combining scenario glazing with chiller’s efficiency will significantly improve the overall energy performance of the building. . conclusion thermal building simulation is a powerful tools to assess the energy performance of a building. the simulation is recommended to be integrated during the design phase of a building. during this stage, there are more opportunities to influence the design of the building and to change the design as it is far cheaper to change the design rather than the real building. moreover, various numbers of scenarios can be modelled in order to obtain the most optimum design, not only on the physical design, but also the operational scenario. nevertheless, in the renovation project, during the planning stage, building thermal simulation plays an important role in providing recommendation for renovation to achieve better performance concerning energy consumption. in this study, different purpose of building thermal simulation is presented. the first case is the role of simulation for designing new building and the second case is for renovation project the simulation results show that in general, the factors that give significant influence to the reduction of cooling energy demand consist of the implementation of high performance glazing material (low shgc value and high light transmission value) for building envelope with majority glass facade, the efficiency of hvac system, task lighting which is represented by lighting sensor, and indoor set point temperature. rahmi andarini / energy procedia ( ) – acknowledgements the building thermal simulation for renovation project was funded by danida environment support programme – danish government under the energy efficiency in industrial, commercial and public sector (eincops) project. references [ ] designbuilder. designbuilder . user manual; . [ ] meteonorm. meteonorm version . . . . switzerland: meteotest; . [ ] designbuilder software, ltd. designbuilder. [ ] national standardization agency of indonesia. sni - - : prosedur audit energi pada bangunan gedung; . [ ] national standardization agency of indonesia. sni - - : konservasi energi sistem pencahayaan pada bangunan gedung; . [ ] national standardization agency of indonesia. sni - - : konservasi energi selubung bangunan pada bangunan gedung; . [ ] national standardization agency of indonesia. sni - - : konservasi energi sistem tata udara pada bangunan gedung; . [ ] national standardization agency of indonesia. sni - - : tata cara perancangan konservasi energi pada bangunan gedung; . [ ] national standardization agency of indonesia. sni - - : label tingkat hemat energi pemanfaatan tenaga listrik untuk keperluan rumah tangga dan sejenisnya; . [ ] andarini r et al. thermal simulation and cooling energy sensitivity analysis of a typical shophouse in jakarta, indonesia. in: building simulation , eleventh international ibpsa conference. glasgow, uk; . p. - . [ ] ashrae standard: standard method of test for the evaluation of building energy analysis computer programs; . [ ] clarke j. energy simulation in building design. nd ed. uk: butterworth-heinemann; . [ ] streicher w. energy efficient buildings. lecture note. institut of thermal engineering, tu graz. austria; . introduction: the energy crisis requires an accelerated application of technology general george a. lincoln* i was asked to provide opening remarks for the rd confer­ ence directed to current problems in energy and resource develop­ ment, an area where, hopefully, x-ray technology can subscribe even more contributions to problem-solving. yesterday i attended the opening day of the federal energy administration hearings-- held a few blocks away. among over speakers there were several whose thesis was "keep off my turf— and maybe there's no energy problem anyway." believe me there is--for all. in noting our technological interest in energy and other resource development, it crossed my mind that our most important resources are our human resources. x-ray technology has made vast contributions to those human resources. as a recipient of the x-ray art rather than a practitioner in your field, can only tell you of problems and suggest objectives. but our society badly needs more, and accelerated, focus of technology on the field of inanimate resources—which we have too long taken for granted as being both plentiful and cheap. henceforth they will be neither. energy is the central pillar of a modern society's ability to do the things it wants to do--to attain the goals of standard of living, improved quality of life, and security of those goals— national security broadly defined. *formerly director, office of emergency preparedness, execu­ tive office of the president, currently adjunct professor of economics and international studies, university o£ denver. while energy is the central theme of my brief remarks, we have to maintain, surveillance and press our technological efforts towards the vast range of primary resources on which our society depends. the strategic and critical materials program of our - country— for which i was responsible for four years of federal office--extended formally from aluminum and antimony through over items to vegetable tannins and zinc. technology was continual­ ly changing that listing and the criticality of the items--for example, making our mica stockpile non-important. oddly enough, energy fuels were never included as strategic or critical, per­ haps because we have always assumed a lavish, uninterrupted supply. there is a definite correlation between resources and our gross production. in a world of expanding consumption, these one-time resources inevitably dwindle. there are consequent in­ creasing costs and an increasing political and strategic signifi­ cance unless our technological and political wisdom finds another way. while the world's bauxite producers, for instance, are un­ likely soon to have the political competence and economic muscle to ape the arab oil embargo, they might some day. meanwhile the rising costs may bring extraction for such resources back to our own country--if technology is wise enough. there are to my mind, three main avenues for probing and advance for all resources including energy. all three avenues must be pressed. this is not an "either-or" business. a maximum effort may still not avoid disaster. firs t , increase our supply capability by such measures as getting more of what exists from the.ground, the ocean bed and, yes, the sun. we, for instance, were recently getting out only percent of oil in known reservoirs. perhaps the tripling in price of crude oil causes a better-record today. second, we must check the increase in demand while maintain­ ing our way of life. the current term for this effort is "con­ servation" which logically includes recycling, extending to our limited water resources. conservation is really a form of effic­ iency and is a program all can support. conservation generally reduces both costs and environmental impacts. it practically always reduces the threat to both our national security and the freedom of our foreign policy. third, there is substitution--use the more abundant and/or more secure resources rather than the less abundant and/or less secure. the obvious energy examples are emphasis on coal and nuclear power. i repeat. all three avenues--supply, conservation, substi­ tution- -are essential, not "either/or" as to expansion of supply, there is a pressing requirement for a team effort among technology, capital and government. en­ ergy , by its nature, requires vast capital inputs— favorite es­ timates are $ billion by and as much as a half trillion dollars by . this capital will only be forthcoming if the price of energy attracts that capital— unless there is a choice of a vast government subsidy, which i think unlikely. the need for wise government input stems from the seemingly inevitable heavy component of government supervision of energy matters as well as the fact that much of future prospective supplies are on government land unless we import those supplies. with a billion r&d budget in five years, as proposed, our financing of that area of effort should be adequate— providing industry sub­ scribes its share. as to conservation, the shock of the arab embargo, coupled with the shock of increased costs has triggered our basic economic reactions— at least temporarily. maybe the embargo should have lasted longer. in and our energy consumption rose about percent annually. according to the chase bank our energy consumption in the first half of fell . percent below that consumption a year earlier. so far so good, although we should beware of the pitfalls of statistical inference; part, or even all, of the situation may be due to slowdown of our economy. the goal of self-sufficiency even by requires that we develop about as much additional energy as we are now producing while cutting back on our consumption growth rate massively. technology produces best when it is in step with obvious economic incentives. jawboning for energy conservation--which i engaged in as a government official--is a weak instrument compared to an energy cost situation which, makes conservation financially re­ munerative to individuals and business who will then support and adopt the needed measures. as to substitution of abundant and/or secure fuels, we here meet the confrontation between our rapid adoption of a belated environmental program and our energy crunch. those of you interested in environmental technology will on self­ examination-- find that you are likely to be pressing for or against solutions to our energy crunch. we should press for re­ conciliation and compromise of that confrontation. true, there are other major problems such as need for capital and the long lead times of development and construction also existent for ex­ pansion of supply. coal, which we have in abundance and which has long been a stepchild of policy, is the central example of our environmental/energy dilemma. we know our coal problems. but thus far the technology to solve them has not been brought on line. hence, while recognizing the unwisdom of our coal situation we are really probably continuing today politically on a course which continues our dependence on scarce and imported oil and gas for percent or more of our energy. i have mentioned costs, capital and environmental factors and hope that you will understand my time problem in failure to mention other matters such as solar power, shortages of water and manpower and our incomplete governmental energy system. that sys­ tem has to be reversed from assumption of plenty and low cost to the opposite. this is hard to do in an election year. but coal, oil, gas and some nuclear power--and energy conservation--are our principal energy resources until circa at least. huclear power today is about the same as wood. we badly need quick pay­ off technology to help bridge the long time gaps between what we may know purely scientifically (which is a lot) and actual mass energy delivery to the consumer. the nuclear breeder program is an example. if successful in carrying through to the end of the next decade with today's technologies, you have only postponed a grim future of energy scarcity unless research and development has by then found new way s . for, looking further down the road, there is no doubt that the world's petroleum age will wane in the lifetimes o£ many here. one reputable study of a great oil company suggests that world export oil will peak as early as . other estimates look to around the year for a waning of petroleum supply--not far away when we are dealing with the current central pillar of the world economy. technology has little time to find a way. currently, the united states and the world are going through economic and politicalj as well as technological, transitions due to energy which are revolutionary. it is a quiet revolution but not thereby less frightening. our suddenly realized dependence on foreign oil--especially on the middle east— cannot help but limit the freedom of action of our foreign policy and gravely impair our national security. an embargo imposed once can more easily be imposed again. in fact, the embargo of last october was made effective by positive action of only three arab states-- kuwait, abu khabi, and saudi arabia. oil power is now power indeed. soon middle eastern oil money power alone may be a serious power in world a£fairs--bofch threat­ ening balance of payments crises and overshadowing the foreign investments of even the united states, a very significant propor­ tion of our exports will go this year to pay for foreign fuel. we will be safer from every standpoint if we pay that same price but for our own indigenous production and conservation. the estimates of oil exporting countries earnings above their absorptive capacity are staggering. reportedly a world bank study sees them as accumulating over a trillion by or times the book value of today's u.s« foreign investments. such financial power could dominate the economic world to an extent not seen since u,s financial power had that dominance post world war ii. there may be an uneasy solace in noting that practically all energy forecasts have proven to be materially in error— as this one may be. our country is in an energy hurry with applied science-tech- nology--as a critical need. harvey brooks, dean of harvard's physics and engineering, is reported to have remarked that our energy crisis is political and economic, not technological. after a life of years in government, four as head of a federal energy agency and over of them as a professor dealing with economics and politics, i regretfully conclude that x have more faith in your and other's technology than in our economic and political wisdom getting there on time and without crack-ups. so it is doubly heartening to meet you all this morning. returning to my role as welcomer; all of our sponsors have faith that when you leave you will be glad you came. we sincerely hope that you will take away a feeling, of both personal and in­ tellectual hospitality from our university and rocky mountain state. untitled annals of the „constantin b rân cuşi” university of târgu jiu, economy series, special issue, vol ii / „academica brÂncuŞi” publisher, issn – /issn-l - energy management systems and iso accreditation in shipping branislav dragoviŠ , romeo meŠtroviŠ , amalia-venera todorut , vassilis Τselentis , maritime faculty, university of montenegro, kotor, montenegro “constantin brancusi” university targu-jiu, education science and public management .department of maritime studies, university of piraeus, piraeus, greece e-mail: branod@ac.me, amalia_venera@yahoo.com, tselenti@unipi.gr abstract the shipping sector is facing new challenges in energy consumption and management. in a recent study conducted by the european sea ports organization (espo) has shown that energy consumption has risen from th place in , to nd in , as far as the environmental priorities of european ports. energy management is seen as the greatest risk for shipping companies, due to the variability existing in the oil and gas markets, in recent decades. unsuccessful energy management strategies have been shown to have serious consequences for the natural environment, as well as for the companies themselves, which include the enhancement of global warming, and the destruction of a positive corporate image/reputation. due to this, shipping companies now consider energy as an integral part of their overall strategy and adopt risk management assessments in order to attain the best returns on their investments. the iso standard provides a useful tool to companies that are eager to develop and apply an efficient energy strategy consistent with modern social corporate responsibility requirements and aspirations. key words: iso , energy management systems, shipping, ports clasification jel : m , m . introduction the european sea ports organization (espo) conducts environmental reviews on a regular basis as shown in table . although air quality remains the number one priority of european ports, energy consumption has become the second priority issue of european ports. since , the importance of energy consumption has raised year over year. one of the reasons is the direct link between energy consumption and the carbon footprint of the ports and climate change [ ]. table . top– environmental priorities of european ports for (espo ) [ ] port development (water) garbage / port waste noise air quality air quality water quality dredging: operations air quality garbage/ port waste energy consumption dredging disposal dredging disposal garbage / port waste energy consumption noise dredging: operations dust dredging: operations noise relationship with local community dust noise dredging: disposal ship waste garbage/ port waste port development (land) air quality relationship with local community relationship with local community ship waste contaminated land hazardous cargo energy consumption dredging: operations port development (land) habitat loss / degradation bunkering dust dust water quality traffic volume port development (land) port development (water) port development (land) dust industrial effluent ship discharge (bilge) port development (land) water quality dredging: operations annals of the „constantin b rân cuşi” university of târgu jiu, economy series, special issue,vol ii / „academica brÂncuŞi” publisher, issn – /issn-l - faced with the global energy crisis and the continuous price increases, companies in recent years actively formulate various energy management options and develop technologies to improve their energy efficiency, thereby reducing harmful emissions such as greenhouse gases and improve the management of limited natural resources [ ] [ ]. measures to reduce energy consumption and environmental pollution are now top issues facing the shipping companies [ ]. the implementation of energy management systems has proved that it can enable companies to identify their potential for reducing energy consumption and increase the efficiency of their operations [ ]. . iso the iso standard also specifies the measurement of energy, the documentation of the required consumption, the reporting, the design and practices for the procurement of equipment and systems and procedures that help to optimize energy efficiency [ ]. additionally, it is worth noting that applies to all variables affecting energy efficiency, which can be monitored and influenced by the organization [ ] and is based on the “plan – do – check – act” principle, as described in diagram , below. diagram . the “plan – do – check – act” principle of iso [ ] iso is a strategic tool that helps businesses and organizationsimplement an energy management system thus making energy usage more efficient. as is described in diagram , iso provides a set of requirements that enable organizations to :  develop a policy for more efficient use of energy  fix targets and objectives to meet that policy  gather data to better understand and make decisions concerning energy use and consumption  measure the results obtained  review the effectiveness of the policy  continually improve energy management energy efficiency management promotes continuous improvement of energy efficiency through i) organizational practices and policies, ii) team development, iii) planning and evaluation, iv) monitoring and measurement, v) communication and employee engagement and vi) evaluation and corrective measures [ ]. the guidelines and steps involved in developing and applying an energy management system are presented in diagram , which include steps for forming an energy policy, design, testing, implementation and systematic monitoring of an energy plan. annals of the „constantin b rân cuşi” university of târgu jiu, economy series, special issue, vol ii/ „academica brÂncuŞi” publisher, issn – /issn-l - diagram . stages and structure of an energy management system [ ] data from [ ] diagram . a generic scheme for energy mapping in a port [ ] data from [ ] these in turn are supported by an internal control system, special monitoring, measurement and analysis. in the case where a deviation from the desired goals occurs, preventive and remedial action alternatives are also provided. the last stage involves a periodic review of the proper application of the model from the top management [ ] a typical example of an energy mapping strategy, necessary to make a public commitment and assess performance and set goals is presented in diagram , where the energy demanding activities of a port are highlighted and analyzed in terms of operations, support/ maintenance functions and buildings. it is evident that an energy management system must be able to highlight and quantify all energy demanding activities, in order to successfully develop and apply an efficient energy management system. . conclusions although the advantages of adopting the above described approach are quite obvious, for many companies, the adoption of a new way of energy management is an important change, which if not properly integrated into the operations and culture of the company, can have the opposite effect [ ] shipping companies are a prime example since workers and management often resist the adoption and integration of energy efficiency management, thus not applying iso correctly [ ]. to understand and overcome this problem an important factors is to strengthen the staff's commitment to a sequential implementation of the stages described above. finally, an important issu e that can reduce the problems created by such a change is the incorporation of the principles of an effective energy management annals of the „constantin b rân cuşi” university of târgu jiu, economy series, special issue, vol ii/ „academica brÂncuŞi” publisher, issn – /issn-l - system into the corporate social responsibility strategy of the shipping business. it has been shown that socially responsible companies that use natural resources more efficiently provide a significant advantage over their competitors in the international market and ensure the growth of their profits in the long term [ ] .bibliography [ ] http://www.espo.be/news/espo-reveals-new-top- -environmental-priorities-o [ ] zhou, q., chan, c.w., tontiwachiwuthikul, p. “development of an intelligent system for monitoring and diagnosis of the carbon dioxide capture process”, j. environ. inform., vol. , no. , pp. – , [ ] mirchi, a., “world energy balance outlook and opec production capacity: implications for global oil security”, energies, vol. , pp. – , [ ] johnson, h., johansson, m., andersson, k. and södahl, b., “will the ship energy efficiency management plan reduce co emissions? a comparison with iso and the ism code”, maritime policy & management, vol. , no. , pp. - , [ ] european commission, “energy efficiency plan”. [ ] mckane, a., desai, d., matteini, m., meffert, w., williams, r., and risser, r. . thinking globally: how iso - energy management can make industrial energy efficiency standard practice. berkeley, ca: lawrence berkeley national laboratory [ ] chiu, t.-y., lo, s.-l. & tsai, y.-y. . establishing an integration-energypractice model for improving energy performance indicators in iso energy management systems. energies , - . [ ] international standards organization iso . energy management systems. http://www.iso.org/iso/iso_ _energy_management_systems.pdf [ ] dutrow e., us environmental protection agency, energy star industrial partnership, may , [ ] boile, m., theofanis s., sdoukopoulos e., plytas,c., . developing a port energy management plan: issues, challenges and prospects, trb annual meeting, washington dc. [ ] sorrell, s, o’malley, e, schleich, j and scott, s., the economics of energy efficiency, elgar: cheltenham, uk., [ ] lloyd's list, “ship-owners still appear reluctant to move towards energy efficiency”, lloyd's list, monday, june , . [ ] Štreimikienė, d., ališauskaitė-Šeškienė, i. and karlaitė, d., “social responsibility of business – important instrument in implementing sustainable energy development”, societal innovations for global growth, vol. , no. , pp. - , . http://www.espo.be/news/espo-reveals-new-top- -environmental-priorities-o http://www.iso.org/iso/iso_ _energy_management_systems.pdf education & debate contraceptives, counselling, and pregnancy in women with sickle cell disease richard j howard, catherine lillis, susan mtuck sickle celi disease is listed in the manufacturers' data sheets in the united kingdom as a contraindication to the use of most combined contraceptive pills; the result is confused advice on family planning to a group ofwomenwho are at substantial risk from both planned and unplanned pregnancy. a study in north london on the use of contraceptives by women with sickle cell disease indicates that the use of combined oral contraceptives is common. although medical staff usually advised against pregnancy, such advice was almost always ignored. over half of the women surveyed had some knowledge about antenatal diag- nosis. family planning advice should be an integral part of the care of women with sickle cell disease. in the absence of specific data to the contrary all methods of contraception may be considered, although with appropriate caution. university department of obstetrics and gynaecology, royal free hospital, london nw qg richard j howard, clinical research fellow catherine lillis, research sister susan mtuck, consultant obstetrician and gynaecologist correspondence to: mr howard. bmj ; : - pregnancy is a considerable undertaking for women with sickle cell disease as it is associated with increased maternal and fetal mortality and morbidity.' contra- ceptive use is therefore an important part of health care for these women; of the widely used methods of contraception, however, there are uncertainties over the safety of two of them. the combined oral contra- ceptive pill has been reportedly associated with increased thrombotic risks, and several authors have cautioned against the use of the intrauterine device. sickle cell disease is listed in the manufacturers' data sheets in the united kingdom as a contraindication to the use of many combined oral contraceptive and postcoital contraceptive pills. because of the severe risks of pregnancy in these women, however, it has been suggested that sickle cell disease should only be a relative contraindication to the use of combined oral contraception. sickle cell disease has been considered not to be a contraindication to the use of injectable progestogens (for example, medroxyprogesterone acetate) or the progestogen only pill, and they are widely used in jamaica. there is a lack of information on the use of contraceptives among women with sickle cell disease in the united kingdom, and this is felt to mirror the confused state of family planning advice provided for these women. we investigated use of contraceptives and complications in women with sickle haemoglobino- pathies. we also assessed the effect of pregnancy counselling and the understanding of inheritance patterns and techniques of antenatal diagnosis. subjects and methods a detailed questionnaire was administered by confi- dential personal interview by a research midwife (cl) to all women with sickle cell disease known to the haematology departments and sickle cell centres of north london. each woman was visited at her local hospital or at home after the object of the survey had been explained by the woman's haematologist or sickle cell counsellor. each woman was asked about her menstrual history, obstetric and gynaecological history, and current and past contraceptive use and problems. the same women were asked firstly, whether anyone had advised them against pregnancy and if so who and had this affected their plans; secondly, if their partner carried sickle cell trait what was the risk of producing a child with sickle cell anaemia; and thirdly, if they were aware of antenatal diagnosis-for example, chorionic villus sampling, amniocentesis, or cord blood sampling by ultrasound guidance. because of the confidential and anonymous nature of the interviews it was not possible to corroborate the women's reports by reference to their hospital medical records. all symptoms and complications given are thus taken from the accounts of the women themselves. ethical committee approval was obtained from all participating hospitals. every effort was made to conduct the survey in as culturally sensitive a manner as possible with the hope of avoiding previously notorious connotations raised by the suggestion of fertility control in these ethnic groups. results a total of women were asked to take part in this study and eight refused. forty two women with sickle cell haemoglobin c disease (hbsc disease), women with sickle thalassaemia disease (hbs ,b thalassaemia), and women with homozygous sickle cell disease (hbss disease) agreed to participate. one hundred and forty nine were sexually active. the age range of the women was - , and the mean was - years. the average age of menarche was years. reproductive patterns there were a total of pregnancies reported from of these women. sixty one pregnancies were planned, were unplanned, and data were missing in . thirty one pregnancies miscarried ( women), and pregnancies were terminated for medical or social reasons ( women). one hundred and thirty seven pregnancies went beyond weeks ( women). contraceptive practices. the table shows the numbers of women using the combined contraceptive pill, the progestogen only pill, the intrauterine device, and injectable progestogens (for example, depo-provera) with the reported side effects. in those women using the combined contracep- tive pill four complained of increased crises (three had homozygous sickle cell disease and one had sickle thalassaemia), and two women reported deep vein thrombosis. the type of pill was not stated but both were assumed to be low dose preparations because of the prescribing policy of the clinic concerned. both bmj volume june o n a p ril b y g u e st. p ro te cte d b y co p yrig h t. h ttp ://w w w .b m j.co m / b m j: first p u b lish e d a s . /b m j. . . o n ju n e . d o w n lo a d e d fro m http://www.bmj.com/ information on contraceptive use in women with sickle haemoglobinopathies intrauterine injectable combined oral contraceptive progestogen contraceptive progestogen only pill device (depo-provera) (n= ( /o) (n= ( %) (n= ( %) (n= ( %) factor women years*) women years*) women years*) women years*) side effect: irregular bleeding ( %) ( %) ( %) dysmenorrhoea ( %) ( - %) menorrhagia ( %) ( %) ( - %) oligomenorrhoea/ amenorrhoea ( . %) ( - %) weight gain ( - %) ( %) ( - %) nausea ( %) infection ( - %) forgot ( - %) ( - /o) headaches ( %) ( - %) migraine ( %) deep vein thrombosis ( - %) increased crises ( - / ) ( . /o) depression ( - %) ( %) failures ofcontraception none discontinued for side effects none *total length oftime all women had been using method ofcontraception. had homozygous sickle cell disease. one was aged and had used the pill for one year; she had gall stones and chronic leg ulcers resulting from her sickle cell disease. the other was aged and had used the pill for three years and was otherwise in good health. barrier contraception was used at some time by women and the expected problems of discomfort, inconvenience, and messiness were reported. there were nine contraceptive failures. fourteen women had undergone sterilisation. counselitng we found that of the sexually active patients, had been advised against pregnancy. forty nine were so advised by medical staff-that is, from haematology, gynaecology, and family planning clinics or from their general practitioner. despite this advice only three women said that this either had or would influence their plans regarding pregnancy. of the three, one woman was sterilised at the age of with severe regrets, and two women reluctantly followed the advice given. only women were correct in their understanding of inheritance patterns in sickle cell disease, and women were aware of the possibility of antenatal diagnosis for sickle cell disease. discussion counselling and uptake of antenatal diagnosis an estimated infants are born with sickle cell disease in the united kingdom annually.! efforts to reduce this presuppose that patients should be well informed about the condition and will elect to have prenatal diagnosis and termination of an affected fetus. this ignores the complex issues in sickle cell disease, which is often compared misleadingly with ( thalas- saemia major. this is acknowledged to be a more severe condition in which aggressive counselling and prenatal diagnosis programmes will reduce the number of affected infants born. our finding that only % of women with sickle cell disease were correct in their understanding of the inheritance pattern for sickle cell disease probably indicates that the question asked was too difficult. we are encouraged that % had heard of antenatal diagnosis, suggesting that awareness of genetic trans- mission to offspring is higher. factors influencing a couple's decision to take up antenatal diagnosis are complex. one study of couples with sickle cell trait in north london showed that those who were offered prenatal diagnosis but refused it tended not to have been informed about sickle cell disease before counselling or they had no existing children with sickle cell disease or had children who were not severely affected.' other factors influencing their decision included a poor obstetric history and rejection of abortion, mainly on moral grounds. data from north america" and the united kingdom' show that prenatal diagnosis is requested by only about half of those couples identified as at risk, and even when prenatal diagnosis indicates sickle cell disease termination is not always requested." contraceptive use we found that % of all women had used the combined contraceptive pill at some time, with % having used the intrauterine device. this is similar to results from north america where it was found that % used the combined contraceptive pill and - % used the intrauterine device.' most authors have now concluded that the intrauterine device is safe in women with sickle cell disease ; the theoretical risk of endometritis and tube ovarian abscess with the added possibility of provoking sickling crises, which has been cited by some workers, has not been proved. there are more data on the use of injectable progestogens- for example, depo-provera-and several authors have reported on its safety. ' ' of the women in our series who had used injectable progestogens there were no reports of serious side effects. our finding of two women with a history of a deep vein thrombosis when taking the contraceptive pill is disturbing. both gave a history to the researcher of admission to hospital and anticoagulation, but we were unable to verify this from hospital records because of the confidential nature of the study. reports available on the safety of the combined contraceptive pill are contradictory, with some authors stating that thrombosis, tissue infarction, and sickling may be increased by the oestrogen component. this view is not universal with others concluding that combined oral contraceptives are safe in women with sickle cell disease.' there have been two case reports of women with sickle cell trait who had thrombo- embolism while taking the combined contraceptive pill. no convincing case is made, however, to justify the implication that their sickle cell trait had any relevance. there has also been a report of two women with sickle cell haemoglobin c disease who had pulmonary infarction while taking the combined contraceptive pill.' the report does not in fact provide evidence, however, to justify the conclusion that this was a thromboembolic infarction as opposed to pulmonary sickling or infection, or both. all these women were taking high dose pills, and we can find no reports of thrombosis on modem low dose pills. we feel that such case reports may have unwittingly generated the current widespread confusion among practitioners on this issue. we also found that four women had increased crises while on the contraceptive pill, and there are few other reports of this. one year study of patients with sickle cell anaemia who were on contraceptives containing oestrogen indicated that there were no adverse effects on the clinical course of these women with only one having possibly related sickling crises.' reproductive patterns the high rate of unplanned pregnancy in this group of women would suggest that the use of contraceptives is far from adequate. our finding that one third have been advised against pregnancy contrasts with the evident lack of effective advice on contraception shown by the rate of unplanned pregnancy of - %. this is higher than that reported by a previous similar study, in which the rate was %./o a weakness of our study is acknowledged in the lack of a control population to assess rates of unplanned pregnancy in the general bmj volume june o n a p ril b y g u e st. p ro te cte d b y co p yrig h t. h ttp ://w w w .b m j.co m / b m j: first p u b lish e d a s . /b m j. . . o n ju n e . d o w n lo a d e d fro m http://www.bmj.com/ population; a previous report, however, suggests it is around %. ° many of these unplanned pregnancies will be terminated; in our study the figure of % agrees with evidence to suggest that one in five pregnancies are terminated in the united kingdom. conclusion the confused medical awareness of which contra- ceptive methods are appropriate may partly explain why advice to women with sickle cell disease is often lacking. we cannot exclude a possible risk of crises and thrombotic episodes with the use of the combined contraceptive pill. despite this, we do not consider it to be contraindicated in this group of women as any complications should be balanced against the substantial risks of pregnancy. we feel that all methods of contraception may be considered in women with sickle haemoglobinopathies, though with appropriate caution. we gratefully acknowledge generous financial support from scar (sickle cell anaemia relief) and the invaluable cooperation of the north london haemoglobinopathy group and the sickle cell centres of north london. tuck sm, studd jww. pregnancy in sickle cell disease in the uk. brj obstet gynaecol ; : - . foster hw. contraceptives in sickle cell disease. south medj ; : - . evans dik. sickle cells and hormonal contraception. british journal of family planning ; o: - . perkinsrp.contraceptionforsicklers. nengl_med ; : . morrison jc. hemoglobinopathies and pregnancy. cgin obstet gynecol ; : - . louden n, ed. handbook of family planning. nd ed. london: churchill livingstone, . sergeant gr. sickle haemoglobin and pregnancy. bmj ; : - . petrou m, modell b, darr a, old j, kin e, weatherall d. antenatal diagnosis. how to deliver a comprehensive service in the united kingdom. ann n yacad sci ; : - . loukopoulos d, hadji a, papadakis m, karababa p, sinopoulou k, boussiou m, et al. prenatal diagnosis of thalassaemia and of the sickle cell syndromes in greece. ann n yacad sci ; : - . anionwu en, patel n, kanji g, renges h, brozovic m. counselling for prenatal diagnosis of sickle cell disease and thalassaemia major: a four year experience. jmed genet ; : . rowley pt, loader s, sutera cj, walden m, kozyra a. prenatal screening for haemoglobinopathies. i. a prospective clinical trial. am j hum genet ; : - . samuels-reid jh, scott rb, brown we. contraceptive practices and reproductive patterns in sickle cell disease. j natl med assoc ; : - . charache s, niebl jr. pregnancy and sickle cell disease. clin haematol ; : - . de ceulaer k, gruber c, hayes r, serjeant gr. medroxyprogesterone acetate. and homozygous sickle cell disease. lancet ;ii: - . freie hmp. sickle cell diseases and hormonal contraception. acta obstet gynecol scand ; : - . lutcher cl, milner pf. contraceptive-induced vascular occlusive events in sickle cell disorders-fact or fiction? clin res ; : a. greenwald jg. stroke in a woman with sickle cell trait taking oral contracep- toves. conn med ; : - . hargus ep, shearin r, colon ar. pulmonary embolism in a female adolescent with sickle cell trait and oral contraceptive use. am j obstet gynecol ; : - . haynes rl, dunn jm. oral contraceptives, thrombosis, and sickle cell haemoglobinopathies. jama ; : - . fleissig a. unintended pregnancies and the use of contraception: changes from to . bm ; : . smith t. unwanted pregnancies. bmj ; : . (accepted april ) why have child pedestrian death rates fallen? ian roberts injury prevention research centre, department of community health, university ofauckland, private bag , auckland, new zealand ian roberts, health research council trainingfellow bmj ; : - pedestrian injuries are a leading cause of childhood mortality and disability. over the past two decades in britain child pedestrian death rates have fallen despite large increases in traffic volume. in this paper roberts examines the likely reasons for this decline. he argues that neither prevention pro- grammes nor improvements in medical care are a plausible explanation and that the decline is most likely the result of a substantial reduction in children's traffic exposure. he believes, however, that restricting children's traffic exposure exacer- bates socioeconomic differentials in childhood mortality and denies children their right to mobility. roberts is convinced that one answer is for british transport policy to be aimed at providing mobility equitably rather than struggling to meet the ever increasing demands ofcar travel. between and in england and wales an average of children were killed each year on the roads as pedestrians. for every death around children required hospital admission for injuries.' pedestrian injuries were among the leading causes of childhood admission to intensive care facilities. between % and % of these children have severe head injuries and are likely to experience long term disability.' with the more widespread recognition of the public health importance of child pedestrian injuries in recent years several epidemiological studies have been mounted aimed at identifying modifiable risk factors. these studies have used case-control or cohort methods in an attempt to identify the factors which place some children at high risk of pedestrian injury." however, an effective public health response to the problem of child pedestrian injury demands that a second aetio- logical issue should be addressed. this concerns the identification of determinants of the incidence, attempting to understand why child pedestrian death rates change over time. answering this question is likely to be as important as identifying risk factors, because if the determinants of the incidence could be identified it might be possible to control them, with gains for the whole child population. over the past two decades child pedestrian death rates have fallen in many developed countries. in england and wales between and the pedes- trian mortality among children aged - years fell by %, and among children aged - years it fell by %. to gain an insight into why child pedestrian death rates have fallen changes in the potential deter- minants of the child pedestrian death rate must be considered. potential determinants ofchild pedestrian deaths the determinants of incidence are most readily identified when their prevalence changes abruptly. for this reason the effect of traffic volume on child pedestrian mortality was most evident during the energy crisis, when an increase in the price of petrol had a measurable effect on the growth in traffic volume. in new zealand government restrictions on car use in the aftermath of the energy crisis effectively arrested the growth in traffic volume for seven years, during which there was a - % reduction in child pedestrian mortality. before this the death rate had been increasing in parallel with increasing traffic volumes. that the rate fell, as opposed to levelling off in line with traffic volume, suggests that there were other processes operating, tending to reduce the mortality, but which became evident only when traffic bmj volume june o n a p ril b y g u e st. p ro te cte d b y co p yrig h t. h ttp ://w w w .b m j.co m / b m j: first p u b lish e d a s . /b m j. . . o n ju n e . d o w n lo a d e d fro m http://www.bmj.com/ decentralised renewable energy and prosperity for lebanon energy policy xxx (xxxx) xxx please cite this article as: henrietta l. moore, hannah collins, energy policy, https://doi.org/ . /j.enpol. . - /© the authors. published by elsevier ltd. this is an open access article under the cc by license (http://creativecommons.org/licenses/by/ . /). decentralised renewable energy and prosperity for lebanon henrietta l. moore *, hannah collins institute for global prosperity, floor , maple house, tottenham court road, london, w t nf, united kingdom a b s t r a c t this paper reviews and updates the current renewable energy (re) policy landscape in lebanon. the focus is on opportunities for decentralised re to not only address lebanon’s insufficient energy supply but the compounding challenges of mass displacement and changing climate. in recent years lebanon has made great progress in re despite the ongoing regional turbulence but more could be done to utilise the countries abundance of renewable resources, growing population and entre- preneurial acumen. energy policy from a prosperity perspective is informed by the role public services play in people’s self-defined aspirations of what it means to live a good life. with the policy support from above, locally managed and decentralised re supply has potential to not only address the energy crisis but also mitigate the impacts of mass migration and climate change, setting lebanon on a path to a sustainable and prosperous future. . introduction for the most part there is agreement on the need to transition to sustainable economies but little agreement on what the transition and the corresponding policies could look like. by looking at energy policy beyond just the macroeconomic questions and contribution to infra- structure development, we look at the benefit of transformations of energy systems in terms of people’s quality of life and the role public services play in building capacities and capabilities. this is important for countries that have sustained systemic shocks, such as war and mass displacement, and are also experiencing the threat of the climate emergency. when devising policies for transformation through complex challenges it is important to keep in mind the need for citizen-based focus on quality of life. this paper looks at what is happening in lebanon and why renewable energy, in its nature, addresses carbon emissions and future prosperity. traditionally, literature on lebanon’s energy policy has focused on classical economic analysis, but there is a shift in global understanding, away from traditional economic models which emphasise economic growth to prosperity (jackson, ; moore, ; stiglitz et al., ). prosperity encapsulates what we value and how we can all flourish in culturally and historically specific ways within the confines of our planet’s resources. the strength and challenge of global prosperity is in its foundation; that there are diverse ways to flourish and no single model of development. we need to engage with diversity to create inclusive sustainable change, tying social value to economic value (moore, ). in the context of lebanon, a prosperity lens is crucial to create energy policy that can address the needs of a population that has dramatically increased due to mass-displacement (yassin, ), and is facing the current and predicted impacts of climate change (ministry of environment, ; ministry of foreign affairs of the netherlands, ; annd, ). to bring the energy policy landscape up to date in lebanon we explore the current policy frameworks, the drivers that are shaping it and the re projects that have already been implemented. prosperity for lebanon is dependent on a re transition, inextricably linked to public services. this complex inter-dependency means that a reliable energy supply would improve the wellbeing, employability, safety, health and education for residents of lebanon. energy policy in lebanon should focus on decentralisation, informed by lebanon’s citizens who are already engaging in re alternatives to the energy crisis. . challenges for energy policy in lebanon the impact of climate change covers the entire economy of lebanon and all aspects of the environment which is vulnerable to the rising sea levels and heat waves (ministry of foreign affairs of the netherlands, ). by lebanon is expected to face chronic water shortages (annd, ) with some estimating sea levels to rise cm in the next years (undp, a). water shortages and heat waves will add * corresponding author. e-mail address: igpdirector@ucl.ac.uk (h.l. moore). independent scholar. contents lists available at sciencedirect energy policy journal homepage: http://www.elsevier.com/locate/enpol https://doi.org/ . /j.enpol. . received may ; received in revised form september ; accepted november mailto:igpdirector@ucl.ac.uk www.sciencedirect.com/science/journal/ https://http://www.elsevier.com/locate/enpol https://doi.org/ . /j.enpol. . https://doi.org/ . /j.enpol. . https://doi.org/ . /j.enpol. . http://creativecommons.org/licenses/by/ . / energy policy xxx (xxxx) xxx additional strains to a struggling energy system. projections for tem- perature rises of between �c to �c by are estimated to lead to an annual increase in electricity consumption for cooling between . % and . % (ministry of environment, ). there is a mixed response in lebanon to the changing landscape of energy investment and the ippc ( ) deadlines on climate change. lebanon is searching for its first oil and gas reserves but has committed to reducing its greenhouse gas emissions by at least % by and up to % with the conditional support of international actors (undp, ). the electricity sector in lebanon is responsible for over % of the national greenhouse gas emissions (undp, ) and imported fossil fuels still account for % of all energy supply and provision (oecd/iea, ). the current model of energy provision is failing to acknowledge the prosperity of future generations. electricit�e du liban (edl) holds the monopoly of energy supply in lebanon. it is a vertically integrated national utility accountable to the ministry of energy and water (moew) which is responsible for policy formulation for electricity, fuel and water sectors. overall responsibility rests with the council of ministers (com) chaired by the prime minister and includes ministries that represent the major political parties in the country (world bank, ). the electricity sector is a huge financial burden on lebanon’s public finances. in edl made an operating loss of usd . billion, with sector subsidies between and aggregating to account for close to half of lebanon’s overall external debt (world bank, ). edl’s tariffs are based on fuel cost of usd per barrel of oil and only cover % of average operating cost in . despite these large sub- sidies, electricity supply is insufficient to meet demand. inadequate energy infrastructure and supply has resulted in endemic power outages. edl utility only covered about % of the electricity demand in . the power gap is estimated at about gw equalling daily cuts for h in beirut and up to h in the bekaa valley (world bank, ). the unreliability of the energy services has become inherent in everyday life in lebanon. ‘illegal’ connections to private diesel genera- tors have been normalised to maintain the necessary electricity to reach basic requirements for households and businesses (abi ghanem, ). the percentage of ‘illegal’ connections to the grid result in a financial burden on the national economy exceeding usd million per year (aems, ). in , % of lebanon’s households relied on diesel generators to back-up power supply, with over % of households paying . % of their income to secure electricity (undp-cedro, a). residents pay a double electricity bill; one for edl and the other for back-up generation, almost twice that of edl, which results in the highest electricity bills in the region (fardoun et al., ). neigh- bourhoods are allocated one private energy provider, with the backing of politicians, who do not face competition and can set their own fees (mohsen, ). they are further legitimised through local tariffs aimed at them. new housing blocks are built with space for generators so new tenants have little choice but to enter accept this informal arrangement (verdeil, ; abi ghanem, ). this contractual and physical entanglement of private generators in daily life reflects the adaptability of the population creating their own access to this intrinsic service. since the civil war lebanon has relied heavily on energy imports. the dependence on oil imports not only contaminates the environment it increases the vulnerability of the lebanese economy to fluctuating oil prices (un escwa, ). there is global consensus (un sustainable development goal ; undp, b) that energy is crucial not only as a basic requirement to live a good life, but across all economic activities, as drivers of new industries and innovation and for information and communication technologies. electricity shortages are a feature of daily life that undermine the social contract, recovery will not be possible without a -h energy supply and future sustainable prosperity is dependent on that supply coming from renewable sources. compounding this is the fact that twenty-five percent of people living in lebanon are displaced people from the syrian civil war, the highest percentage refugee population of any country in the world. this does not include the registered palestinian refugees (unrwa, ). while the inadequate energy supply predates the syrian civil war significantly the influx of people not only strains the system even more, it means that like the lebanese, displaced people in lebanon in both formal and informal settings are not obtaining the required electricity to operate basic household appliances. governments and international actors recognise that the ‘refugee crisis’ is not a short-term emergency, but more could be done to implement policies to build energy resilience in communities. new and existing models of energy delivery in lebanon must recognise the challenge of climate change and people’s energy needs across varied contexts, considering socio-economic conditions and self-defined aspirations for prosperity. . . re technology and policy in lebanon lebanon has achieved a great deal in recent years, from a country with no re vision to a regional sustainability hub with renewable and energy efficiency targets (lcec, ). the landscape of energy policy in lebanon is complex incorporating different actors and drivers. the rise of re technology can be directly linked to certain policies and projects highlighting the crucial role of government and policy makers in supporting a re transition. the lebanese centre for energy conservation (lcec) was initiated as a joint project between the moew and the undp in . their main objective was to create a national energy agency to push for energy ef- ficiency and they are now the national energy agency for lebanon affiliated to the moew but with a financially and administratively in- dependent statute (lcec, ). the first milestone for the development of re in lebanon came in when the moew committed to the policy paper for the electricity sector (ppes) to launch, support and reinforce public, private and individual initiatives to adopt re, and to reach % of electric and thermal supply from re by . in the government of lebanon (gol) further pledged a switch to natural gas and re in their capital investment plan (cip; gol, ) and extended the target to % of electricity and heat consumption through renewables by (irena, ). the national energy efficiency and renewable energy action (neerea) is a national financing mechanism initiated in by leb- anese central bank (bdl) with support from the european union and technical assistance from lcec. it provides incentives for re projects through interest free and long-term loans (lcec, a). the neerea supports the financing of new and existing energy efficient, re and sustainable building projects. it allows private sector entities to apply for subsidised loans for environmentally friendly projects. by the end of loans had been approved through the neerea totalling usd million. however, financing for largescale re projects are constrained as the neerea only finances re projects for individual consumption, not for independent power production (ipp; un escwa, ). following on from the country’s national energy efficiency plan (neeap – ) lebanon was one of the first countries to develop its own national renewable energy action plans (nreap) – . the nreap – clarifies the individual targets for different re technologies needed to reach the % target by (lcec, , table .). implementation of the nreap – needs between usd million and usd million while the direct cumulative most palestinian refugees in lebanon live across camps where they have no right to work (unrwa, ). they are left out of re initiatives as it is government policy that no permanent infrastructure should be installed in informal settlements. the grid has yet to be restored since it was severely damaged during the lebanese civil war ( – ) and some claim the electricity sector has al- ways struggled to provide -h electricity to lebanon’s inhabitants (abu-rish, ). h.l. moore and h. collins energy policy xxx (xxxx) xxx savings for the economy are estimated at usd million (un escwa, ). the nreap projects implemented by will provide an extra h of electricity with the first to benefit those people in lebanon who are least able to afford the financial burden of the high electricity bills. environmentally, full implementation of the nreap will reduce lebanon’s yearly carbon dioxide emissions by . % (un escwa, ). the nreap – , with updated targets, is due to be released this year (irena, ). today re contribution to total power production in lebanon is estimated at between % and % mainly via hydropower. the only forms of energy produced within lebanon come from solar water heaters and hydroelectric plants (un escwa, ). in approximately % of the total electricity production came from hydroelectricity (lcec, ). the development of hydropower plants depends on the construction of dams, controversial as they threaten lebanon’s biodi- versity (kranz, ). now the water network is so damaged that approximately % of the water gets lost before reaching the end user making constructing more dams without repairing the system wasteful (el solh, ). despite this, dams are continuing to be built hydro- power is estimated to make a significant contribution to the % target (table .) wind power has reached grid parity as a viable and cost-competitive choice for electric power generation and is set to contribute . % to the % target. the national wind atlas of lebanon estimated a wind po- tential of at least mw (undp, in khoury et al., ). earlier this year lebanon signed its first power purchase agreement (ppa) for wind energy in akkar with the combined capacity of mw by (amine, ). technical expertise as well as large investments are needed to implement large-scale wind farms and require significant government support. smaller-scale wind farms or single turbines would help overcome land constraints, engage citizens and increase acceptance of the technology (undp-cedro, ). biomass, with a focus on waste-energy, is set to cover . % of the % target (lcec, ). biomass is a biological material derived from living things which can be used directly via combustion to produce heat, or indirectly after converting it to biofuel (el-jamal, ibrahim and ghandour, ). biomass is the fourth largest energy source and is important as it can produce different forms of energy and resources are common around the world (lcec, ) and offers synergies with other sectors such as waste management, water treatment and forestry (undp-cedro, ). lebanon has a relative abundance of bioenergy resource as one-third of the country’s land is arable. utilising local re- sources and biofuels in is an important component of a re transition for lebanon that the government is failing to recognise. the solar photovoltaic (pv) sector is now established with over competitive companies in lebanon with potential for further growth. solar pv energy production is in abundant supply in lebanon with around days of sunshine per year, for eight to h each day (berjawi et al., ). given that most electricity rationing in lebanon occurs during the day solar energy offers a sustainable alternative to cuts and diesel generators. solar pv plants can be complemented with wind power given that when the sun is not shining the wind is blowing. solar water heaters (swhs) are the most developed re technology in lebanon which has been gaining momentum since the to achieve “a solar water heater for every household,” (bassil, ). the neeap – laid out a financing scheme for the swh market (lcec, ). private banks, initiated through bdl, offer five-year, interest free loans for residential swhs (that do not exceed $ ) and the moew contributes $ to cover capital costs. swh projects that exceed $ can apply for the neerea loan. these loan schemes created momentum in the lebanese swh market which has more than doubled since (lcec, b). thirty-eight percent of the swh systems installed in lebanon were partially or totally manufactured in lebanon (undp-gef, ) showing potential for further market development in other re systems. in edl adopted a net-metering policy which supports the expansion of solar energy in lebanon to households and expanded to communities in . net-metering allows for a two-directional flow of energy, from the grid to the customer and from the customers re facility to the grid using a bi-directional meter (berjawi et al., ). edl does not pay for the net production produced by consumers but credits the excess production to the next bill. more than projects are connected to the net-metering network but due to the lack of meters at edl net amounts must be calculated manually limiting the effectiveness of the policy (un escwa, ). solar energy is to cover one-third of the % target (table .). from to solar pv capacity rose from around . mwp to over mwp, averaging an annual equivalent growth of % (undp-dreg, ). solar pv generation increased from , mwh in to , mwh in constituting . % of the annual electricity genera- tion by edl (undp-dreg, ). the beirut river solar snake comes as part of the neeap – plan to install mw of solar farms by . it is the first solar pv farm at a national level with a total planned output of mw. the private sector designed, built and transferred the re generation plant with government support. only the first stage of the project has been completed adding an extra mw of electricity to the grid (machnouk et al., ). in and , the moew launched two consecutive bids for and pv farms respectively (of – mw each). a new bid has been launched for three pv farms (of – mw each) which includes plans for the first electricity storage of mwh (machnouk et al., ). pierre el khoury, president of the lcec, , said in that the % by target was achievable (the business year, ). but solar pv alone could cover at least the daily power peak load, far outreaching the lcec target (berjawi et al., ). lebanese policy makers underestimate the potential of solar pv in improving energy security, energy billing and reducing the impact of fossil fuels for electricity generation (berjawi et al., ). interlinkages exists between the main actors driving the re sector in lebanon, such as edl, moew, lcec, bdl and the un. on paper they work together and pledge support to the % by target in the nreap – and through the neerea loan scheme. the energy monopoly held by edl means that all actors working in the field must coordinate with edl. in the nreap – the lcec committed to publishing yearly follow-up reports on the progress of implementation (lcec, ). this would show which actors were driving re progress, how it is coordinated and how it was being measured and implemented. the progress report for - have not been produced by lcec. steps have been taken to develop lebanon’s energy sector towards renewable sources, at least to achieve the % by . there is recognition within different sections of government (through the % target goal; nreap – ; the neerea loan scheme; and the cip) and from public (through the uptake of swhs) and private sector (through private banks loans for swhs, the financing of wind farms in akkar and the beirut river solar snake) that re is the way forward. while there is some coordination between the big players of re in lebanon, it is apparent that a lack of legal framework is inhibiting the sector from flourishing and limiting it to small-scale projects rather than a concerted nation-wide effort to transition to re. table percentage contribution for each energy source to the % renewable energy by goal as laid out in nreap – (lcec, ). energy source contribution to the % goal hydropower . % wind power . % biomass (including waste-energy) . % solar energy (pvs, csp, swhs) . % h.l. moore and h. collins energy policy xxx (xxxx) xxx . . constraints and opportunities for a re transition in lebanon the main barrier to full deployment of re technologies is the lack of components and clarity within the existing and outdated institutional and legal frameworks, with reforms hindered by political fractionalisa- tion. regulations are based on industrial traditions and codes, not up to date with sector developments. delays to implementation of legal framework to privatise, liberalise and unbundle the sector have meant that only one wind power programme signed a ppa, under a law that has since expired (un escwa, ). this means that decrees that give edl the monopoly in generation, transmission and distribution are still being applied. a legal regulator to set prices and liaise between government and private power producers has not been appointed. currently, the coms is tasked with assigning ppas. it is not clear which legal process the gol will deploy and this uncertainty is delaying major investments in utility-scale re. a critical challenge for lebanon will be managing governance and transparency in the energy sector but the government’s recent request to join the extractive industries transparency initiative is a step in the right direction (machnouk et al., ). low and not cost-reflective electricity tariffs are a barrier to deployment of re because of the long amortization period. edl cannot increase the tariffs until infrastructure and the grid are reliable, but at the same time edl does not have the finances to improve the systems reliability (undp-cedro, ). edl will be the main customer for all large-scale re projects, but their financial deficit and bankability problems increase the risk of investment. there is no dedicated department with edl for incorporating re into the national grid and no grid codes exist internationally that could be adopted (un escwa, ). we need to look beyond just recalibration of the lebanese energy system in the form of institutional reforms which are slow to implement, to the way decentralised, local production of energy can provide the population with a high standard of reliable, affordable and renewable energy. another constraint to a re transition for lebanon is the vested in- terest throughout the economy in oil imports and the entrenched nature and power of the private generator owners. some estimate the private generator industry to be worth usd billion (rose, ). this gives the owners power and influence over lawmakers in an already fraught po- litical sphere where key energy policy decision makers include the lebanese oil installations directorate and the lebanese petroleum administration (world bank, ). the entanglement of the generators in everyday life and within the distinct socio-political divides is a barrier to new systems of delivery and can inhibit mobilisation against the current energy supply in lebanon (abi ghanem, ). energy policy focussed on re needs to acknowledge this complexity and to engage with and enhance the capacities of both old and new players in the energy business. the prospect of natural resource discovery has generated a great deal of investment interest and political debate (fattouh and mahadeva, ). domestic gas could reduce import dependence and emissions. commissioning of an investment programme for construction of a number of gas-based power plants through the private sector, primarily in salaata, zahrani and deir ammar, are expected to be installed by (world bank, ). the gas market is expected to initially be dominated by gas imports that will eventually partly be replaced by indigenous gas. gas streams will enter the lebanese market at different geographic locations and on different contractual terms but there is no developed legal or physical infrastructure to manage market ownership and structure. the aub policy institute ( ) suggest that the gol needs to play a central role in regulating the gas market. there is po- tential for a hybrid-energy system here that allows for private sector investment in gas and re technologies but this needs to be connected to a broader agenda and policy for long-term prosperity in lebanon. an obstacle to high penetration of re is land availability in lebanon. tfail, an inland region in the bekaa valley on the border with syria, has been shown to include around km of elevated flat lands with high levels of solar irradiation (ayoub and boustany, ). an examination of the technical and economic feasibility of a mw solar pv plant in tfail demonstrates robust technical and financial incentives with lev- elized cost of electricity ranges between . to . cents/kwh of elec- tricity produced. the average annual energy generation over the project’s lifetime is around gwh/year. given the location, such a project could play a role in potential electricity swap deals and trading with the syrian grid in the future (ayoub and boustany, ). this pre-feasibility research is important as it provides information for attracting investors and it has been reported that european bank for reconstruction and development is seeking consultants for a feasibility study for the project (bellini, ). while energy supply in lebanon is insufficient to meet the pop- ulations basic needs and the current re contribution to total supply is minute, for a re transition to be successful people must also be willing to modify their lifestyle through reducing and adapting power consump- tion (khoury et al., ). for a re transition to be successful insights into energy options must be made available to consumers so they can make informed decisions for themselves and the environment. there is potential in the lebanese public’s adaptability to changing their energy supply (abi ghanem, ). the higher the amount people pay for informal generators the more willing they are to pay for re options so designing re programmes that displace diesel generators have a better chance of success and can attract more funding (undp-cedro, ). unemployment in lebanon is subject to a wide-range of estimates with an absence of reliable data. between and total unem- ployment estimates ranged between . % to % (ecosoc, ). while in the lebanese president cited a figure of % unemploy- ment due to the presence of displaced syrian (the daily star, , march ). lebanon has identified agriculture, infrastructure and environment as sectors with potential for employability for displaced people making investment and action in re infrastructure an employ- ment solution for people in lebanon. analysis of the re technology value chain in lebanon estimates that , jobs could result from the deployment of re technologies by , the bulk being in the solar pv sector (undp-cedro, ). a study by irena and un escwa, found strengths for local manufacturing in lebanon, where industries related to electronics, steel, aluminium and plastics are well developed and can play a role in stim- ulating the re industry. furthermore, university programmes associated with re research mean that the technical know-how is available and there is good potential for local integration and manufacturing of re technology in lebanon (irena and un escwa, ). with the absence of reliable and continuous electricity decentralised re systems are among the easiest to deploy, are cost-effective and sus- tainable. the costs of re are less than that of diesel generators and less than the average costs edl pays for energy distribution and generation (irena and un escwa, ). while the legal and political hurdles are constraining large-scale re projects, the opportunities for a re transi- tion in lebanon and future prosperity are in decentralised community-led projects. . re successes in lebanon by looking to the re successes in lebanon, future energy systems will need a combination of on- and off-grid hybrid technology, will be decentralised and will come from the ground up. not only do they create a reliable energy network, they have knock-on benefits through new value chains and benefit the education, health and safety of communities. in partnership with the moew, edl, the council for development this is not just a lebanese problem, changing mindsets in the age of con- sumption is a significant hurdle towards re transitions worldwide (loveday et al., ; von borgstede, andersson & johnsson, ; shi et al., ). h.l. moore and h. collins energy policy xxx (xxxx) xxx and reconstruction and lcec, the undp is managing the country en- ergy efficiency and re demonstration project for the recovery of lebanon (cedro) since . now in its th phase, cedro aims to find cost effective and environmentally beneficial ways to transform the energy system (undp-cedro, b). since more than small-scale re applications have been implemented nationwide including pv, micro-wind, solar pv street lighting, swhs and ground source heat pump projects to both host and refugee populations. in cedro completed ‘village ’ initiative the first community-led re system in lebanon (undp-cedro, b). approximately households in kabrikha in southern lebanon signed up to the scheme entirely powered by kwp solar pv coupled with diesel generators. it is the first community to utilise the net-metering policy. the electricity expenses have dropped % and the village no longer experiences power cuts (euinlebanon, ). the initiative al- lows a community-scale re powerplant to plug into the separate local grid that is owned and operated by the municipality when the power is cut, and then allows the same re power to plug into the utility network when national power is available (undp-cedro, b). it is expected that this model will lead to the implementation of other community-led re systems (whether solar, wind or bioenergy) that provide energy se- curity, environmental benefits, community cooperation and economies of scale (undp-cedro, b). historically, lebanon has been known for its entrepreneurial acumen (ahmed and julian, ). data from the global entrepreneurship monitor ( ) for shows that . % of – -year olds are established business owners, . % are either a nascent entrepreneur or owner-manager of a new business, and . % see good opportu- nities to start a business in the place they live. but entrepreneurs in lebanon are constrained by high electricity costs and unstable supply as well as the hybrid-political order that can channel entrepreneurial talent into bribery and lobbying (stel and naud�e, ). the reinforcement of family-owned business and entrepreneurs with connections to govern- ment (stel and naud�e, ) limits the potential for new re entrepre- neurs by limiting the diversity of ideas and knowledge. with new generations coming to age there is a global shift in the social contract, seen in the extinction rebellion movement and the likes of greta thurnberg, decisions must be made that acknowledge and ac- count for the planet’s finite resources. the millennial generation con- stitutes approximately % of the lebanese population (youth policy, n. d.). lebanese youth are challenging the status quo (krastrissianakis et al., ) with the popular, spontaneous and leaderless october mass proests further attesting to this, showing the potential to generate action to change the energy sector. they have already played as essential role in the growth in lebanese civil society (abiyaghi et al., ) and are set to become power players in the region in the next years. the millennial generation have grown up with power cuts as a daily presence and are finding creative ways to solve the energy crisis utilising the potential for re technology. lebanese based social enterprises which offer re solutions are contributing to the growth in the solar energy industry. for example, millennial run otb consult partnered with greenpeace to train young lebanese and refugees living in lebanon with the skills to enter the solar energy market (greenpeace, n.d.). lebanon’s entrepreneurs have the capability to contribute to re provision, sup- porting the rebuild of communities, the country and the next trans- formation phase that will be fuelled by the rise of robotics and artificial intelligence. . policy recommendations and conclusion the current energy situation in lebanon is not only a heavy burden macroeconomically but on new and old resident’s quality of life and future prosperity. enabling policies are needed to ensure effective innovation, supply and consumption of renewable technologies. policies must continuously adapt to the changing market conditions to ensure greater cost-competitiveness. the gol should adopt and enforce more aggressive targets for re to contribute to the . c ipcc target. the current targets outlined in the nreap are unambitious and do not reflect the successes and growth of the re sector potential (undp-cedro, ). lowering taxes on re products and adopting a grid code for the lebanese context would allow the industry to flourish. the institutional challenges of edl must be addressed by adjusting tariffs to reflect actual costs and by encouraging new expertise into edl through regular employment processes. the use of another agency attached to moew could work as a buffer customer for re projects (un escwa, ). institutional and legal reforms need to be implemented to encourage private sector investment in re infrastructure. until this urgent action is implemented decentralised distribution of re offers a pathway that does not only hinge on government perfor- mance. a hybrid model of local ownership could help redefine energy citizenship and encourage people to engage with issues of energy access and payment. community ownership is already a common ownership model in lebanon, with buildings collectively buying generators to share, indicating there is traction for change and opportunities for decentralised approaches (institute for global prosperity, ). there needs to be policy recognition and research into the entan- glement of energy provision shaping people’s lives. the issam fares institute proposes that the best strategy to address private generator owners would be to involve them in the process of transitioning the economy to re (dziadosz, ). a transition would include diversifi- cation of energy supply, energy demand management and energy trade, particularly intra-regionally. when looking for pathways to trans- formation it is essential we break down the consumer versus producer binary or the state versus community dichotomy, coming up with new solutions to the energy crisis premised on citizen control over their own lives and the resources of their communities. energy policy should reflect this. decentralisation of re systems changes the dynamic of how we think about energy and may help to change the way we use it. new forms of localism are taking hold around the world that are an opportunity for re transitions. local authorities need to be able to play an active role in controlling, spreading and efficiently using re 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http://www.youthpolicy.org/mappings/regionalyouthscenes/mena/facts/ http://www.youthpolicy.org/mappings/regionalyouthscenes/mena/facts/ 	decentralised renewable energy and prosperity for lebanon 	 introduction 	 challenges for energy policy in lebanon 	 . re technology and policy in lebanon 	 . constraints and opportunities for a re transition in lebanon 	 re successes in lebanon 	 policy recommendations and conclusion 	funding 	declaration of competing interest 	references myofascial pain (rd gerwin, section editor) etiology of myofascial trigger points carel bron & jan d. dommerholt # the author(s) . this article is published with open access at springerlink.com abstract myofascial pain syndrome (mps) is described as the sensory, motor, and autonomic symptoms caused by myofascial trigger points (trps). knowing the potential causes of trps is important to prevent their development and recurrence, but also to inactivate and eliminate existing trps. there is general agreement that muscle overuse or direct trauma to the muscle can lead to the development of trps. muscle overload is hypothesized to be the result of sustained or repetitive low-level muscle contractions, eccen- tric muscle contractions, and maximal or submaximal con- centric muscle contractions. trps may develop during occupational, recreational, or sports activities when muscle use exceeds muscle capacity and normal recovery is disturbed. keywords etiology . myofascial . pain . trigger points . muscle damage . calcium .sustainedlow-levelcontractions . eccentric . cinderella hypothesis introduction myofascial pain syndrome (mps) is described as the senso- ry, motor, and autonomic symptoms caused by myofascial trigger points (trps). trps are defined as exquisitely tender spots in discrete taut bands of hardened muscle that produce local and referred pain, among other symptoms. a trp is composed of numerous so-called contraction knots. an in- dividual contraction knot appears as a segment of a muscle fiber with extremely contracted sarcomeres and an increased diameter. the integrated trp hypothesis postulates that in myofascial pain motor endplates release excessive acetyl- choline, which is evidenced histopathologically by the pres- ence of sarcomere shortening [ ]. these areas of intense focal sarcomere contraction have been described in animals and humans. an active trp causes a clinical pain complaint. it is always tender and refers a patient-recognized pain on com- pression. it prevents full lengthening of the muscle, weakens the muscle, and mediates a local twitch response of muscle fibers when adequately stimulated. when compressed with- in the patient’s pain tolerance, it produces referred motor and often autonomic phenomena, generally in its pain ref- erence zone [ ]. a latent trp is “clinically quiescent with respect to spontaneous pain; it is painful only when palpat- ed. a latent trp may have all the other clinical character- istics of an active trp and always has a taut band that increases muscle tension and restricts range of motion” [ ]. trps are very common, although literature about their prevalence is sparse [ – ]. knowing the potential causes of trps is important to prevent their development and recurrence, but also to c. bron scientific institute for quality of healthcare, radboud university nijmegen medical centre, nijmegen, the netherlands c. bron (*) practice for physical therapy for neck, shoulder and upper extremity disorders, paulus potterstraat , tk, groningen, the netherlands e-mail: carelbron@mac.com j. d. dommerholt bethesda physiocare inc. and myopain seminars llc, old georgetown road, suite c- , bethesda, md - , usa j. d. dommerholt universidad ceu cardenal herrera, valencia, spain j. d. dommerholt shenandoah university, winchester, va, usa curr pain headache rep doi . /s - - - inactivate and eliminate existing trps. there is general agreement that any kind of muscle overuse or direct trauma to the muscle can lead to the development of trps. muscle overload is thought to be the result of sustained or repetitive low-level muscle contractions, eccentric muscle contrac- tions, and maximal or submaximal concentric muscle con- tractions [ ]. although muscle damage is not required for the development of trp, there may be a disruption of the cell membrane, damage to the sarcoplasmic reticulum with a subsequent release of high amounts of calcium-ions, and disruption of cytoskeletal proteins, such as desmin, titin, and dystrophin. ragged red (rr) fibers and increased numbers of cytochrome-c-oxidase (cox) negative fibers are com- mon in patients with myalgia, which are suggestive of an impaired oxidative metabolism [ ]. sustained low-level contractions and intramuscular pressure mechanical muscle overuse can be defined as the result of muscle contractions that exceed muscle capacity. since the capillary blood pressure ranges from approximately mm hg at the beginning (arterial side) to mm hg at the end of the capillary beds (venous side), the capillary blood flow is temporarily obstructed during muscle contractions. the blood flow recovers immediately with relaxation, which is consistent with its normal physiological mechanism. in dy- namic rhythmic contractions, intramuscular blood flow is enhanced by this contraction-relaxation rhythm, also known as the muscular pump. during sustained muscle contrac- tions, however, muscle metabolism is highly dependent upon oxygen and glucose, which are in short supply. even contractions performed at only % and % of capacity or maximum voluntary contraction (mvc) may produce intramuscular pressures high enough to significant- ly impair the intramuscular blood circulation. the associa- tion of the percentage of mvc and intramuscular pressure (imp) is highly dependent upon the architecture of the muscle. it has been postulated that the percentage of mvc reported as the upper limit for localized muscle fatigue varies between muscles, because of the variation of imp during a contraction. for example, % of mvc of the supraspinatus muscle produces approximately mm hg of imp, while % of mvc of the trapezius muscle is good for only mm hg of pressure. even lower values of imp may affect muscle metabolism [ ]. the emg signs of localized muscle fatigue did not recover until the muscle contraction pressure was below mm hg in the biceps muscle [ ]. according to otten, the increased pressure gradients during low-level exertions may contribute to the development of pain [ ] and eventually to the formation of trps (personal communication ). since oxygen and glucose are required for the synthesis of adenosine triphosphate (atp), which provides the energy needed for muscle contractions, sustained contractions may cause a local energy crisis due to the lack of oxygen. to guarantee an adequate supply of atp, the muscle can switch within a few seconds to anaerobic glycolysis. during the initial phase of glycolysis (sugar splitting) glucose molecule is broken down into pyruvic molecules releasing enough energy to form atp molecules. under aerobic circumstan- ces, oxygen reacts with pyruvic acid producing a high amount of atp ( molecules per pyruvic acid molecule), carbon dioxide and water. under anaerobic circumstances, however, most of the pyruvic acid produced during glycolysis is con- verted into lactic acid, thereby increasing the intramuscular acidity (ph). most of the lactic acid diffuses out of the muscle into the bloodstream; post-exercise lactic acid is washed out within minutes after exercise. unfortunately, when the capillary circulation is restricted, as in sustained low-level contractions, this process comes to a standstill. researchers at the us national institutes of health found that in the direct environment of active trps, the ph may be well below , which is more than sufficient to excite muscle nociceptors, including acid-sensing ion channels (eg, asic and ), and the transient receptor potential vanilloid re- ceptor trpv [ , ]. small increases of the h+ concen- tration, as seen with inflammation, heavy muscle work, and ischemia, are sufficient to excite muscle group iv endings, contributing to mechanical hyperalgesia and central sensiti- zation [ ]. furthermore, a low ph downregulates acetyl- cholinesterase (ache), increases the efficacy of acetylcholine (ach), and maintains the sarcomere (super-) contraction. it also triggers the release of several nociceptive substances, such as calcitonin gene-related peptide (cgrp) [ ], which can enhance the release of ach from the motor endplate and simultaneously decrease the effectiveness of ache in the synaptic cleft. cgrp also upregulates the ach-receptors (achr) at the muscle and thereby creates more docking stations for ach. miniature endplate activity depends on the state of the achr and on the local concen- tration of ach, which is the result of ach-release, reuptake, and breakdown by ache [ ]. relaxation within the muscle cells occurs when myosin- actin cross-bridges detach. after atp is attached to the myosin molecule, the link between myosin and actin weak- ens, and the myosin head detaches from actin. in other words, the cross-bridge between myosin and actin ‘breaks’. simultaneously, the ca + ion detaches from the troponin molecule, which blocks tropomyosin. under normal physi- ological circumstances, large amounts of free calcium-ions will reenter the sarcoplasmic reticulum by the ca + pump (calcium atpase), which places a high demand on atp during relaxation. in case of severe energy depletion, the sarcomeres may stay contracted, until enough atp is curr pain headache rep available to resolve the intracellular ca + accumulation. high concentrations of intracellular ca + are associated with sustained sarcomere contraction and muscle damage. ca + accumulation due to sustained motor unit activity has been suggested to play a causative role in the development of muscle disorders and trps [ ]. in a preliminary study using doppler ultrasound, sikdar et al have shown that blood flow waveforms show signifi- cant differences between active trps, latent trps and normal sites. the flow waveforms near active sites showed in- creased systolic velocities and flow reversal with negative diastolic velocities [ •]. they identified contributing factors, namely an increase in the volume of the vascular compartment, and an increased outflow resistance. in- creased outflow resistance could be due to muscle contrac- tures at the trp that compress the capillary or venous bed. sustained low-level contractions are common in the work- place where many occupations rely on prolonged postures, as seen in musicians, supermarket cashiers, computer oper- ators, hairdressers, and dentists, among others. dynamic concentric contractions cinderella hypothesis henneman, working with anesthetized cats, showed that in response to increasing physiological excitation, motor neu- rons are recruited in order of increasing size. this fundamen- tally important finding was verified in humans by milner- brown et al [ ] and is now generally accepted. smaller motor units have a smaller alpha-motor neuron cell body, smaller axons and fewer muscle fibers to activate compared with larger ones. according to the size principle, small motor units innervating type i red colored, slow oxidative fibers are recruited first, followed by red to pink colored, fast oxidative fibers, and finally by white colored, fast glycolytic fibers. furthermore, small type i muscle fibers are activated during prolonged tasks [ ], although a few studies have described some degree of motor unit substitution [ ]. hägg suggested that the continuous activity of these motor units in sustained contractions causes overuse muscle fiber damage, especially to the type i fibers during low-level activities, which he summarized in his cinderella hypothesis [ ]. it is conceiv- able that in sustained low-level contractions and in dynamic repetitive contractions, ischemia, hypoxia and insufficient atp synthesis in type i motor unit fibers are responsible for increasing acidity, ca + accumulation, and subsequently sar- comere contracture. furthermore, starting with the sarcomere (super-) contraction, the intramuscular perfusion slows down and ischemia and hypoxia will occur. this may lead to the release of several sensitizing substances causing peripheral sensitization [ , ]. maximal or submaximal concentric contractions during (sub-) maximal concentric contractions high amounts of energy (atp) are required. initially, atp is utilized from storage depots within the muscle fibers itself. after about – seconds, the muscle shifts to direct phosphorylation of adp by creatine phosphate (cp). phosphorylation produ- ces atp by coupling phosphate group to an adp molecule catalyzed by the enzyme creatine kinase. stored atp and cp provide enough energy for maximum muscle power for ap- proximately – seconds. hereafter, a short period of rest is needed to replenish the exhausted reserves of intracellular atp and cp. when ongoing atp demands are within the capacity of the aerobic pathway, muscular activity can contin- ue for hours in well-conditioned individuals. however, when the demands of exercise begin to exceed the ability of the muscle cells to carry out the necessary reactions quickly enough, anaerobe glycolysis will contribute more and more of the total generated atp. finally, the muscle will run out of atp and sustained sarcomere contractions may occur, starting the development of trps. eccentric contractions during normal activity muscles are often active while being lengthened. this is referred to as an eccentric contraction [ ]. classic examples of this are walking, whereby the knee extensors are active while being lengthened just after heel strike while the knee flexes; placing an object gently downwards, whereby the arm flexors are active while being lengthened to control the rate of movement of the object. in other words, eccentric contractions are commonly used to control the rate of movement. in another scenario, the load on the muscle may increase to the point where the external force on the muscle is greater than the force that the muscle can generate. in that case, the muscle is forced to lengthen due to the high external load. there is no solid evidence that eccentric loading would lead to the development of trps, but as gerwin et al sum- marized, there is much overlap between the mechanisms of eccentric contraction and the development of trps [ ]. in one study, itoh et al found that healthy volunteers presented with tender ropy taut bands, which were painful on com- pression, immediately after sets of eccentric exercises of the middle finger extensor muscle [ ]. one day and days after the exercises the findings were similar. after days the muscles were recovered. while this study suggests that eccentric loading does contribute to the development of trps, the study also employed isometric loading in addition to eccentric loading, which precludes definitive conclusions. there is evidence from biopsy studies that during eccen- tric contractions disruption of the cytoskeletal structures curr pain headache rep occurs, especially of the protein desmin that interconnects the adjacent myofibrils [ , ] and of titin, the largest protein in the human body. titin connects myosin filaments to the z-bands and is also linked to actin filaments [ , ]. microscopic research revealed increased sections of abnor- mal fibers in eccentrically exercised muscles [ , ], which appeared to be approximately times the normal size [ ]. this was only observed with eccentric exercise, and not with concentric exercise or passive stretching. furthermore, all enlarged fibers were exclusively of the fast glycolytic type or fast contracting type ii fibers that are highly fatiga- ble. it is hypothesized that early in the exercise period fast glycolytic fibers fatigue as they are unable to regenerate atp and as a result they enter into a rigor or high stiffness state. subsequent stretching of the stiff fibers mechanically disrupts the fibers resulting in cytoskeletal and myofibrillar damage. there is also evidence that in eccentric exercised muscles the intracellular concentration of calcium is in- creased, probably because of disruption of the sarcoplasmic reticulum. as we have seen before high concentrations of ca + keep myosin and actin molecules together. further- more, increased ca + has the potential for activating several mechanisms that leads to further damage of the cell mem- brane and cytoskeletal disruption. in contrast, hocking has postulated that eccentric loading does not provide a good model for the trp pathogenesis. he suggested that sustained partial depo- larization or plateau depolarization of an α-motor neu- ron dendrites leads to lasting alterations in the function of the entire α-motor neuron [ ] due to an upregula- tion of l- or n- type voltage dependent calcium chan- nels and α -adrenergic receptors and a downregulation of calcium-activated potassium channels, which would lead to an increase in the motor terminal cytosolic calcium ion concentration (personal communication, ). he suspects that the increased calcium concen- tration triggers the spontaneous release of ach. in other words, according to hocking, the increased ach release would be the cause and not the result of the energy crisis. alpha- -adrenergic receptors are linked to l-type voltage dependent calcium channels, which would sug- gest that sympathetic activity would increase the cyto- solic calcium ion concentration and the excessive release of ach [ ]. rather than looking at overuse mechanisms, hocking maintains that persistent nocicep- tive input causes the formation of trps through central sensitization of the c-fiber nociceptive withdrawal reflex and plateau depolarization of withdrawal agonist alpha- motor neurons and compensatory reticulospinal motor facilitation of antigravity muscles and plateau depolar- ization of withdrawal antagonist alpha-motor neurons [ ]. future research in the underlying mechanisms of trp is much needed. clinical example eccentric contractions occur during all activities of daily life, but have been researched especially in sports. overhead throwing, spiking in tennis and volleyball, javelin-throwing, downhill running, jumping and running (landing phase) involve eccentric activities. during the deceleration phase of throwing, the posterior shoulder muscles such as the infraspinatus, teres minor and major, posterior deltoid, and latissimus dorsi muscles, contract eccentrically not only to decelerate horizontal adduction and internal rotation of the arm, but also to resist shoulder distraction and anterior subluxation forces. a shoulder compressive force slightly greater than bodyweight is generated to resist shoulder distraction, while a posterior shear force of %– % bodyweight is generated to resist shoulder anterior sublux- ation. consequently, high activity is generated by the pos- terior shoulder musculature, in particular the rotator cuff muscles. the percentage of maximum voluntary isometric contraction (mvic) is calculated in studies using needle electromyography. for example, the teres minor exhibits its maximum activity ( % of mvic), the infraspinatus %, supraspinatus %, posterior deltoid %, latissimus %, subscapularis %, and triceps % during the deceleration phase. scapular muscles also exhibit high ac- tivity to control scapular elevation, protraction, and rotation during this phase. the lower trapezius muscle, which exerts force on the scapula in the direction of depression, retraction and upward rotation, generated its highest activity during the eccentric phase [ •]. high emg activity from gleno- humeral and scapular musculature during eccentric contrac- tion illustrates the vulnerability of the posterior musculature for developing trps in the overhead-throwing athlete. posterior shoulder pain is a common complaint of throw- ing athletes and is mostly explained by posterior impinge- ment [ , ]. interestingly, stretching exercises have been shown to assist in reducing the athlete’s pain and to normal- ize shoulder motion, particularly shoulder internal rotation and horizontal adduction. it is common for the overhead thrower to exhibit loss of internal rotation of ° or more, referred to as “glenohumeral internal rotation deficit (gird).” this internal rotation deficit has been suggested to be a cause of specific shoulder injuries. wilk expressed that loss of internal rotation is most often due to osseous adaptations of the humerus and posterior muscle tightness, and not posterior capsular tightness. stretching exercises, including the sleeper’s stretch and supine horizontal adduc- tion with internal rotation, are advised to improve the flex- ibility of the posterior musculature, which may become tight because of the muscle contraction during the deceleration phase of throwing [ ]. trps can be found in many sports- men, including elite volleyball players, swimmers, and runners [ – ]. curr pain headache rep conclusions in spite of a lack of well-designed studies, the best available evidence supports that trps develop after muscle overuse. several potential mechanisms may play a role, such as eccentric overload, submaximal sustained, and (sub)-maxi- mal concentric contractions. a key factor is the local ische- mia, which leads to a lowered ph and a subsequent release of several inflammatory mediators in muscle tissue. hock- ing proposed an interesting counterargument, which deserves further exploration. whether overuse mechanisms are the crucial initiating factor or persistent nociceptive input remains a point of debate and further study. disclosures no potential conflicts of interest relevant to this article were reported. open access this article is distributed under the terms of the creative commons attribution license which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. references papers of particular interest, published recently, have been highlighted as: • of importance . simons d. review of enigmatic mtrps as a common cause of enigmatic musculoskeletal pain and dysfunction. j electromyogr kinesiol. ; : – . . simons d, travell jg, simons ls. myofascial pain and dysfunction. the trigger point manual. upper half of body. nd ed. baltimore: lippincott, williams and wilkins; . . fricton j, kroening r, haley d, siegert r. myofascial pain syn- drome of the head and neck: a review of clinical characteristics of patients. oral surg oral med oral pathol. ; : – . epub / / . . fishbain d, goldberg m, meagher b, steele r, rosomoff h. male and female chronic pain patients categorized by dsm-iii psychi- atric diagnostic criteria. pain. ; : – . epub / / . . skootsky sa, jaeger b, oye r. prevalence of myofascial pain in general internal 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the ieee embs. . this is an interesting paper presenting a theoretical model to understand the role of vascular compression in trigger point formation. . de luca cj, contessa p. hierarchical control of motor units in voluntary contractions. j neurophysiol. ; : – . epub / / . . zennaro d, laubli t, krebs d, klipstein a, krueger h. continuous, intermitted and sporadic motor unit activity in the trapezius muscle during prolonged computer work. j electromyogr kinesiol. ; : – . epub / / . . henneman e. relation between size of neurons and their suscep- tibility to discharge. science. ; : – . epub / / . . hagg gm. human muscle fibre abnormalities related to occupa- tional load. eur j appl physiol. ; : – . epub / / . . hoyle ja, marras ws, sheedy je, hart de. effects of postural and visual stressors on myofascial trigger point development and motor unit rotation during computer work. j electromyogr kinesiol. ; : – . epub / / . . lieber rl. skeletal muscle structure, function, and plasticity. the physiological basis of rehabilitation. rd ed. baltimore- philadelphia: lippincott, williams & wilkins; . . gerwin rd, dommerholt j, shah jp. an expansion of simons’ integrated hypothesis of trigger point formation. curr pain head- ache rep. ; : – . epub / / . . itoh k, okada k, kawakita k. a proposed experimental model of myofascial trigger points in human muscle after slow eccentric exer- cise. acupunct med. ; : – . discussion– . epub / / . . barash ia, peters d, friden j, lutz gj, lieber rl. desmin cytoskeletal modifications after a bout of eccentric exercise in the rat. am j physiol regul integr comp physiol. ; : r – . epub / / . . lieber rl, shah s, friden j. cytoskeletal disruption after eccentric contraction-induced muscle injury. clin orthop relat res. ; :s – . epub / / . . niederlander n, raynaud f, astier c, chaussepied p. regulation of the actin-myosin interaction by titin. eur j biochem. ; : – . epub / / . . nagy a, cacciafesta p, grama l, kengyel a, malnasi-csizmadia a, kellermayer ms. differential actin binding along the pevk domain of skeletal muscle titin. j cell sci. ; (pt ): – . epub / / . curr pain headache rep . lieber rl, friden j. selective damage of fast glycolytic muscle fibres with eccentric contraction of the rabbit tibialis anterior. acta physiol scand. ; : – . epub / / . . lieber rl, friden j. muscle damage is not a function of muscle force but active muscle strain. j appl physiol. ; : – . epub / / . . friden j, lieber rl. segmental muscle fiber lesions after repetitive eccentric contractions. cell tissue res. ; : – . epub / / . . hocking mjl. trigger points and central modulation - a new hypothesis. j musculoskeletal pain. ; : – . . wessler i, dooley dj, osswald h, schlemmer f. differential blockade by nifedipine and omega-conotoxin gvia of alpha - and beta -adrenoceptor-controlled calcium channels on motor nerve terminals of the rat. neurosci lett. ; : – . epub / / . . • escamilla rf, yamashiro k, paulos l. shoulder muscle activity and function in common shoulder rehabilitation exercises. sports med. . this is an interesting paper presenting the results of electromyography research in shoulder movements. . myers j. glenohumeral range of motion deficits and posterior shoulder tightness in throwers with pathologic internal impinge- ment. am j sports med. ; : – . . mcfarland e, hsu c, neira c, o'neil o. internal impingement of the shoulder: a clinical and arthroscopic analysis. j shoulder elbow surg. ; : – . . wilk ke, obma p, simpson cd, cain el, dugas jr, andrews jr. shoulder injuries in the overhead athlete. j orthop sports phys ther. ; : – . . osborne nj, gatt it. management of shoulder injuries using dry needling in elite volleyball players. acupunct med. ; : – . epub / / . . hidalgo-lozano a, fernandez-de-las-penas c, calderon-soto c, domingo-camara a, madeleine p, arroyo-morales m. elite swim- mers with and without unilateral shoulder pain: mechanical hyper- algesia and active/latent muscle trigger points in neck-shoulder muscles. scand j med sci sports. . epub / / . . fredericson m, guillet m, debenedictis l. innovative solutions for iliotibial band syndrome. phys sportsmed. ; : – . epub / / . curr pain headache rep 	etiology of myofascial trigger points 	abstract 	introduction 	sustained low-level contractions and intramuscular pressure 	dynamic concentric contractions 	cinderella hypothesis 	maximal or submaximal concentric contractions 	eccentric contractions 	clinical example 	conclusions 	references 	papers of particular interest, published recently, have been highlighted as: • of importance household energy economics in rural ethiopia: a cost-benefit analysis of biogas energy household energy economics in rural ethiopia: a cost-benefit analysis of biogas energy s.g. gwavuya a, s. abele a,*, i. barfuss b, m. zeller a, j. müller b a department of rural development theory and policy, universität hohenheim, stuttgart, germany b department of agricultural engineering, tropics and subtropics group, universität hohenheim, , germany a r t i c l e i n f o article history: received may accepted april available online may keywords: rural energy firewood dung biogas cost-benefit analysis ethiopia a b s t r a c t limited success in promoting improved energy sources, such as biogas, in rural areas of developing countries has been partly blamed on insufficient understanding of household energy use patterns. in this study, we assess the costs of energy generation from major energy sources (firewood and dung) in rural ethiopia, as well as the economic potential of biogas as an alternative in addressing both energy and food security challenges. results show that households in rural areas largely collect their own fuel, with female household members being mainly responsible for the chore. by investing in biogas plants, households could save time and energy, and have a supply of slurry that can be used as fertilizer in agricultural production. a cost-benefit analysis of biogas plants yields positive net present values for households collecting their own energy sources. even higher net present values are obtained for households purchasing all of their energy needs; these households stand to gain significantly from the financial benefits of energy cost savings with biogas technology. results are highly dependent on slurry being effectively used as a source of fertilizer and on the price of the replaced energy source. thus the promotion of slurry use as fertilizer must be an integral part of a successful biogas programme. another important issue is that at present, biogas plants are highly subsidized and thus the above conditions hold under the assumptions of subsidies. when analysed without subsidies, indicators are still positive, yet amortisation periods are significantly longer and close to the depreciation point, so that investment risks increase. � elsevier ltd. all rights reserved. . introduction africa’s energy challenges have been described as major and severe despite the existence of great energy potentials on the continent [ e ]. access to modern energy systems remains a chal- lenge in sub-saharan africa despite reserves of petroleum, natural gas and coal, which in accounted for nearly %, % and % of world reserves respectively, and the potential of hydro-, solar and geothermal energy sources [ ]. consequently, biomass, consisting of firewood, charcoal, dung and crop residues, remains the main source of energy in sub-saharan africa [ e ]. the current widespread and inefficient use of biomass energy has implications on the environment, human health and food security [ e ]. deaths from acute respiratory infections as a result of indoor air pollution have been estimated at around . million annually, which is higher than malaria deaths and almost half of hiv/aids deaths [ ]. women and children are the most affected as their exposure to indoor air pollution is higher than that of men [ , ]. air pollution also contributes to greenhouse gases (ghgs) leading to climate change [ ]. high demand for firewood (and its charcoal form) in urban areas has been linked to increased defor- estation [ ]. household productivity is affected by the reallocation of time and labour from yield bearing activities to the collection of biomass energy [ ]. households also lose productive time due to ill health [ ]. biomass combustion in general and dung and crop residue combustion in particular amount to nutrient export from agricultural land [ ]. like other sub-saharan countries, ethiopia is highly dependent on biomass for energy; households in rural areas are almost completely dependent on biomass for their energy needs [ ]. firewood is becoming scarce in ethiopia where increasing pop- ulation pressure, land degradation, deforestation and loss of soil nutrients continue to worsen both food security and the energy crisis [ , ]. with the increasing shortage of firewood, households are turning to dung and crop residues for energy. this new reliance * corresponding author. tel.: þ ; fax: þ . e-mail addresses: s.abele@uni-hohenheim.de, steffen.abele@kabelbw.de (s. abele). contents lists available at sciverse sciencedirect renewable energy journal homepage: www.elsevier.com/locate/renene - /$ e see front matter � elsevier ltd. all rights reserved. doi: . /j.renene. . . renewable energy ( ) e delta: _given name delta: _given name delta: _surname delta: _given name delta: _given name delta: _surname delta: _given name delta: _given name delta: _surname delta: _given name mailto:s.abele@uni-hohenheim.de mailto:steffen.abele@kabelbw.de www.sciencedirect.com/science/journal/ http://www.elsevier.com/locate/renene http://dx.doi.org/ . /j.renene. . . http://dx.doi.org/ . /j.renene. . . http://dx.doi.org/ . /j.renene. . . further contributes to environmental, human health and food security problems. consequently, there is a need to jointly address energy and food security challenges [ , ]. the lack of success in promoting cleaner and improved energy sources in sub-saharan africa is partly due to the limited under- standing of household energy use patterns [ ]. relatively few studies have focused on household energy use in africa [ ]. biogas offers a technically feasible energy alternative in rural areas and helps mitigate some of the consequences of extensive biomass energy use [ , ]. ethiopia, where the technology has been promoted since to kerb the energy crisis, has, according to the undp/world bank energy management assistance program (esmap), a biogas potential of up to two million family units [ ]. a feasibility study carried out by eshete et al. ( ) revealed that of ethiopia’s e domestic biogas plants, about % have stopped functioning due to water and dung shortages, technical problems, abandonment and loss of interest [ ]. a similar trend was observed by ethiopian energy authority (eea) [ ]. despite past failures the country has recently set up a multiple stakeholder driven biogas programme implemented by the national biogas programme ethiopia (nbpe) to develop a viable and sustainable commercial biogas sector [ ]. one of the earlier studies on biogas in ethiopia has been conducted by seyoum ( ) [ ]. a more recent study undertaken by renwick et al. in also deals with the financial performance of biogas plants in sub-saharan africa as a whole, including, but not solely focused on, ethiopia [ ]. we follow the conclusions of their research which propose further studies examining market segmentation with respect to different potential target household types. therefore, the main objective of the study is to provide a detailed analysis across different segments of the potential target groups and plant types. in particular, we segment the potential demand situations for biogas plants in three energy source scenarios, namely for households purchasing fire- wood, collecting firewood, and collecting dung. in a sensitivity analysis, we differentiate households according to their income. we also discuss two different sizes of biogas plants with m and m fermenter volume. as the majority of potential target households live in rural areas with agriculture as their main economic activity, we have a closer look at the potential linkages between agriculture and biogas plants by computing the fertilizer value of slurry as a by- product in the process. . materials and methods . . study area and data household surveys for the study were conducted in two woredas (districts), dale in the southern nations nationalities and peoples region (snnpr) and arsi negele in oromiya region, both of which are located around awassa, the regional capital of snnpr. awassa is approximately km south of the ethiopian capital addis ababa. the snnpr and oromiya regions are two of the four regions tar- geted by the nbpe. the two woredas, one from each region, were selected because of their different dung usage habits: in arsi negele dung is commonly used as both fertilizer and a source of energy for cooking, while in dale it is primarily used as fertilizer. . . data collection the rural farm household, defined in this study as a group of people sharing the same hearth and depending mainly on agri- culture for their livelihood in a rural area [ ], is the sampling unit. a multistage stratified sampling method was used to obtain study kebeles (villages). a complete list of kebeles was constructed with the help of local authorities at woreda level taking into consideration different regions for consideration of agro-ecological and climatic factors as availability of firewood varies by climatic region. four kebeles were randomly selected for the study. proba- bility proportional to size (pps) sampling method was used to select households at kebele level. at each kebele, a list of households was obtained from the kebele office and systematic random sampling was used to select study households. a standard household questionnaire applied in a survey in april and may of was used for primary data collection. the ques- tionnaire at household level covered demography, income sources (on- and off-farm), resource and asset endowment, land cultivation, agricultural input use and crop yields, food availability and access, food security status, and labour and energy management. a total of four key informant interviews, one at each kebele, were also con- ducted to obtain information on land ownership, livestock owner- ship and energy sources usage. key informants included administrative officials and developmental extension officers. additionally, selected markets in survey areas were visited to check on available energy sources and their respective prices. . . conceptual framework we assume that households maximize their utility subject to constraints like resources and budgets. energy sources are inter- mediate consumption goods that carry a cost to the household and are used for different purposes, chief among them household food preparation [ ]. according to newman et al. ( ), energy consumption leads to both (positive) utility but also to (negative) waste and other effects [ ]. these costs and benefits are pivotal in this study to the comparison of main energy sources for rural ethiopia. households make decisions on energy collection and use based on a shadow price [ , ]. shadow prices of energy sources are determined by the economic value of alternative uses of the resources committed for energy generation. households have an option to either purchase or collect energy sources and the shadow price also depends on the trade-off between household budget and time constraints. . . shadow price of energy sources for a functioning market, the market price of an energy source reflects the cost of its use. for energy sources that are not purchased on markets, opportunity costs or shadow prices are determined by time spent collecting the energy source [ ]. following the work of kanagawa and nakata ( ) the following formula was used for calculating opportunity costs of energy sources [ ]. ocei ¼ ocl dei � ti; ( ) where oce is the shadow price per unit of energy (etb/gj), ocl are the opportunity costs of labour (etb/hour), de is the energy (gj/ year) for energy source i and t is the time spent (hours/year) for collection. dung has an additional opportunity cost in its alternative use as fertilizer. tests for determining the fertilizer values were conducted on dried dung samples collected concurrently with the household survey. elementary analysis (dry combustion according dumas) was performed for nitrogen content. the results indicate that on average kg of dung is equivalent to kg of dia- mmoniumphosphate (dap), a common fertilizer in ethiopia, at the time of the study, the exchange rate etb/us $ was . . s.g. gwavuya et al. / renewable energy ( ) e https://isiarticles.com/article/ may , volumiie , numiibcr american associatfion for the advancement of science scietnce serves its readers as a forumn for the pr esentation and disculssion of iiimportant issues related to the advancement of science, incltuding} the presenitation of minorits oi conflictin- points of view, a- ther than by publishing- only :iiatcrial oni which a consensus has been treached. accor d- ingly, altl a ticles lplblished in siie'lc includintg d^cfitot ils, nlews and commcint, and book relviews -are signled and reflect the individulal views of the alut s atild tiot oilicial points of vicv adoptcd bs the aaas oi the institlutions wi ith w hich thlc athor; ,o e aiflilialted. editorial boar(i alfrl) bitowss fr\nk xv. puinani janies f. cronn' \tuxini\. sinif sein'iotr s. kr.t gordon vs n sn i srnk piriss i-lrberi s. gut.ioswsky n. bruci hannay donald kirnrnei d)%ntii e. koshiland, jr. dosn \ll) i intisles itol psi iri k rasynoo h. too nrlson editorial stall editor p'hilip h. abelson plublishler buisine ss maniager willit belvasn hans nussissuri mfanaging editor: robert v. ornies assistant editors: ellen e. murphy, johin e. kingit isi,itstois to iths i/ito ss: . 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( - - ) editortial correspondence: massa- chiisetts ave., nxv, washington. d.c. . phones: (at-ea code ) central oftice: - ) ; book re- viesis: - ; btisines, oflice: - ; ciicula tion: - ; guide to scientific iinstl-inients: - ; neesis aild comimilient: - ; reprints and permissions: - ; research nesss: - , reviessing: - . cable: advancesci. washington. copies of "binst-tictions for conti-ibi tors" can be obtainecl ftomii the eclitorial office. see alio page xx, science, nmarcch . advertising corre- spondence: roomii , w. st. new york, n.y. . p'hotne: -pe- - . scie:nce: media coverage of substantive issues a cursorx e\aimination of ilcws sources lead's to the coiicilusion that citizcels halxve a great nuthliber of opportities to becotie well informned. they caln) x iex programils oil the various television channels. most radio statioils tix e the news att least hourly some continuously-and there are many talk slhows. newspapers and newsweeklies .attempt to carry on their tradditional funlction. yct ;l closer exalinioatioii i cxcvals that the ncwvs mcdia ai rc itot etlective in presenting balanced inews in depth, blut are to a degree contributing to zi iiialfliifctio lilig oof society. they have participcited in creatili tand exacertatillng scelies of crises bs overconceiltraitillni attentioll on par- ticuilair topics. t pically, tif tcr ai period of colicentrated attention, the imcedial suddenl-y drop olne topic as they rulsh to indlulge in ovxerkill ot the next one. these tendenicies were noted by alan l. olten iii a reccilt col iiiin in the woll sitreet jottimitl : which lbegan: (one iilohii rk of contemjporar\ america, it's ftecqueritiv beenl noted, is he shot-t life-spai of its ct ises. a pt'trotl emetciiges studdenly l oilids s ifltly to ci isis pi-opot linis, briefly doinliletes illiu lic con sciolustcss atid concetin, mnd thncibtrut tly faldes firon c'ws is il iehts, tut bandecal y huinger, dirlgs, imee, campulis unrli-est, iciliceld c*t c. tile ccx it on met, ener onc stucceeis anothei 's ith bluringi ispeed, iltmlost its thizol- so ic issuic of-the-year cltb xxerc in cha-re. a glance cit ottenl's list leaves onc with the imapr-essioni ot a variable cim oluint ot resiliuc from the periods of great mass miedia attenitiol. most of the topics listed are nlow practically decid as fcir as the medici are conicerincd. true, there is a considerable residuc tfromii emphasis oni the enivironituicint both in legislition- cnd in puiblic collsness, ailthough with shcirply curtailed miedia coverage, the public conicerin and initercst haive lessenied. after tretmcenidouis attention, niews coverage of the energy crisis hals cilmost discippecared, aind there is little indiccition of suibstanttive progress in mceting the isslic. the basic problems renlain, but the pub- lic is hored with the subject, and the net effect of the coverag,e is to make it morc diflicuilt for progress to be mcide in the fulture. another uinidesirable feature of the massive attention is its lack of qutllity. the bizcirre aind the spectaicular liews takes precedenice over reports with balalnce and suibstance. we at scie,icc frequeintly have op- l-ortilities to evaluate the performance of the medici in llnecirthing the f'acts aibout c given situation, and mor-e often than not we cire dis- cippointed. this is particularly trule in those areas in xx hich scienice and technology titeract with public policy. these issics cire usually com- plex and encdliring a.nd niot well hcandled by slick or sensational joulrn.alistii. the cuirrentipractices of the mass miedia point the value of ptib- icactions like ,scic;icc' that cire desigined to informa rather thacn to excite. althoulgh our resources are comnpairatively odest, wxc feel no handiclcp in comtipeti;ig. oit aily topic we choose to cover, we can if we wish produllce ci maore roulided, coniiplete, balcnced, cind scholarly story. usu- cilly we dlo niot choose to comapete on topics that are being well covcred bv others. 'we prefer to pilipoitit issucs before they cire in vogue, alid we cire not civerse to decililn with significcint topics after others have dropped the!)), provided there is niew cid relevant inforimiationi. in ouir eflorts to m))ainitain qulality, wc are fortuinlatc in hcavi n a recider- ship thcit expects good pertorlalnce. ouir iluthors understcand this alid telilc to behcave accordingly. we are also fortuncinte in hciving cin alidicilce that v ilues rigor cind discussioni in depth and is willing to conitilrbite ideis, time, cind maoney to the commion objective.-pl i_.w h. abet son a. l. otten, wall .s tetjjoirnta/, mciv , p. . o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ media coverage of substantive issues philip h. abelson doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the trademark of aaas. is a registeredscienceadvancement of science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for thescience by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ tipping the energy balance toward longevity cell metabolism previews tipping the energy balance toward longevity william mair ,* department of genetics and complex diseases, harvard school of public health, huntington avenue, boston, ma , usa *correspondence: wmair@hsph.harvard.edu http://dx.doi.org/ . /j.cmet. . . ampk is a cellular energy sensor conserved across eukaryotes that in c. elegans prolongs life span and mimics dietary restriction. stenesen and colleagues ( ) activate ampk both directly and indirectly by altering amp biosynthesis to slow aging in drosophila, highlighting ampk as a conserved life span modulator that links energy sensing to longevity. for an organism to survive, it must main- tain energy homeostasis by tightly regu- lating the balance between anabolic processes that generate energy and cata- bolic ones that eat into reserves. fine- tuning this balance becomes especially critical when energy intake is low, leaving cells without adequate supply to meet demand. in such cases, organisms from yeast to mammals avoid energy crisis by implementing austerity measures, reallo- cating limited resources from growth and reproduction toward self-preserva- tion and survival (fontana et al., ). strikingly, animals in this thrifty state show remarkable resistance to multiple age-onset pathologies, including cancer, metabolic disease, and neurodegenera- tive disorders. in this issue of cell metab- olism, stenesen et al. ( ) use genetic approaches to disrupt energy balance and slow aging in the fruit fly drosophila melanogaster, reinforcing the idea that energetics, metabolism and longevity are tightly linked and that altering steady- state energy levels may be a means to treat age-related diseases. to identify genes linking energy homeostasis to longevity, stenesen and coworkers performed a two-pronged forward genetics screen in drosophila, seeking mutations that both increased life span and specifically affected genes expressed in metabolically active tissues. of ten significantly long-lived fly mutants, flies carrying mutations in the gene encoding adenylosuccinate synthetase (adss), a key metabolic enzyme involved in the synthesis of adenosine monophos- phate (amp), showed the strongest effects. amp can be generated from both de novo synthesis and salvage path- ways and is a nucleotide precursor of adenosine triphosphate (atp), which acts as the critical energy source for most cellular processes. confirming that the increase in longevity was not specific to adss, stenesen et al. tested the life span of flies harboring mutants in multiple genes involved in amp biosyn- thesis, and in each case they saw life span extension. to determine the effect these prolon- gevity mutations were having on cellular energetics, stenesen et al. used high-per- formance liquid chromatography (hplc) to measure amp and atp availability as a readout of energy balance. surprisingly, despite disrupting amp biosynthesis, each long-lived mutant showed increases in both total amp and the ratio of amp::atp, mimicking the effects of energy depletion (figure ). increases to the amp::atp ratio are indicative of energy imbalance, with more energy being utilized than is produced. when such imbalance is detected, cells attempt to restore energy homeostasis by inhibit- ing anabolic processes that use energy and activating catabolic ones that pro- duce it. in eukaryotes, the key orches- trator of this homeostatic process is amp-activated protein kinase (ampk), which is activated by increased amp:: atp and as such acts as a cellular fuel gauge (hardie et al., ). ampk is activated during energy limiting condi- tions known to extend life span, and its dysregulation is associated with multiple age-related diseases (steinberg and kemp, ). as such, targeting ampk has been suggested as a means of reca- pitulating the protective effects of energy restriction (fontana et al., ). how- ever, to date the effect of ampk activation on survival has only been tested in the nematode worm c. elegans, the result being long lived animals that mimicked those under energy stress despite being well fed (apfeld et al., ). cell metabolism stenesen et al. tested whether ampk was both necessary and sufficient for the longevity effects of disrupted amp biosynthesis. as expected, given the rise in amp::atp ratios, ampk activity was indeed increased in the long-lived flies. further, ampk activation was required for the longevity effects, as expressing a dominant negative form of ampk completely suppressed the life span increase of adss mutants. in a final tour de force of fly genetics, stenesen and coworkers used a conditional gene switch system to activate ampk specifically in metabolic tissues in adult flies. the re- sulting ampk gain-of-function animals showed increases in life span comparable to that of adss mutants, suggesting that increased ampk activity is sufficient for the longevity effects of disruptions to amp biosynthesis pathways. these data support the theory that tar- geting ampk might ameliorate diseases of aging, but also raise further questions. first, what are the identities of down- stream mediators responsible for the effects? life span extension by activating ampk in c. elegans requires both activa- tion of the foxo transcription factor daf- (greer et al., ) and inactivation of the transcriptional coactivator crtc- (mair et al., ). whether these ampk targets work together or separately to mediate longevity remains unclear. both are well conserved in drosophila and humans, and testing their roles in longevity will yield valuable insight. that disruptions to pathways gener- ating amp results in increased amp levels is counterintuitive. given that amp can be generated by de novo and salvage pathways, and as a byproduct of the conversion of adp to atp ( adp # amp + atp), it is possible that inhibiting one branch of amp biosynthesis feeds , january , ª elsevier inc. mailto:wmair@hsph.harvard.edu http://dx.doi.org/ . /j.cmet. . . a b figure . tipping the energy balance: mutations in amp biosynthesis pathways increase the amp::atp ratio to increase longevity (a) under normal conditions, de novo and salvage pathways are active, synthesizing amp, which is con- verted to atp, resulting in a low amp::atp ratio and normal life span. (b) mutations in genes involved in amp biosynthesis swing the energy balance to mimic a low-energy state. amp::atp ratios are increased, promoting longevity via activation of ampk. cell metabolism previews back to upregulate compensation in another. how this results in an increase in amp::atp ratios warrants further investigation. ultimately the goal of the aging field is to generate small molecules that promote healthy aging in order to treat age-onset disease, and here again the new data raise interesting questions. metformin is the most widely prescribed treatment for type ii diabetes and a known potent acti- vator of ampk (hardie et al., ). high doses of metformin have been shown to increase life span in c. elegans in an ampk dependent manner (onken and driscoll, ), yet recent data show that this effect is not conserved in drosophila (slack et al., ). that activating ampk can increase life span in fruit flies, cell metabolism , january , ª yet metformin supplementation does not, suggests that either feeding metfor- min does not activate ampk in the rele- vant tissues for life span extension in drosophila, or that off target effects of metformin might be limiting longevity in spite of its effects on ampk. alternatively, perhaps activating ampk in all tissues in drosophila is detrimental to health. ubiq- uitous expression of the active ampk used by stenesen et al. would determine whether ampk promotes longevity non- cell autonomously when expressed in one tissue or whether tissue-specific acti- vation simply recapitulates a fraction of what might be achievable if ampk were active in multiple tissue types. the data of stenesen et al. show that ampk can promote healthy aging in elsevier inc. organisms beyond c. elegans. as such, they add life span extension to the growing list of conserved physiological effects mediated by ampk (hardie et al., ). the role of ampk in sens- ing resources and maintaining energy balance is conserved from worm to fly to mouse to humans. if the longevity data presented by stenesen et al. in this issue represent the first step on a similar conservation ladder, targeting ampk to tip the energy balance toward healthy aging in humans might provide protection against the ever-growing burden of age- related pathologies. references apfeld, j., o’connor, g., mcdonagh, t., diste- fano, p.s., and curtis, r. 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( ). cell metab. , this issue, – . 	tipping the energy balance toward longevity 	references association affairs quo vadis industrial science? there was a proposal last year to abolish the industrial science section (p) of the aaas. however, after con- sideration at its recent meeting, the committee on council affairs did no,t recommend dissolution. hence, while we are not well, at least we are alive! we are heartened by this decision, since we believe that in today's and tomorrow's world the potentials of sec- tion p are great, both in terms of rele- vance and in terms of utility. most of those who favored the abol- ishment did so without comment. in general, those who did comment took the attitude that if the section cannot do any better than it has done in the past, then perhaps it is best to do away with it. but those who defended its purposes, objectives, and potentials did so convincingly and eloquently, while at the same time calling for a renais- sance. bringing this renaissance about at what do you want in a co incubator? lab-line has it! do you want a radiant hot-wall heated chamber? no water jacket. lab-line has it! do you want a built-in automatic de-gradientator and de-stratifier which completely eliminates gradi- ents and stratification of c -air mixture throughout the chamber? lab-line has it! do you want . . controlled humidities from am- bient to % rh? lab-line has it! do you want . . dual chambers and controls that permits each chamber to operate at separate tem- peratures, humidities and c tensions or identical operating conditions? lab-line has it! do you want . . an automatic kwik-lnject mech- anism which injects the exact amount of c into the chamber when door is closed for speedy re- co",ry of c atmosphere? lab-line has it! do you want . . an exclusive "window-dor", for full visibility of chamber without disturbing contents or c atmosphere? lab-line has it! lab-line combines these exclusive features and more in a complete line of c incubators, in all sizes to fit your exact requirements. for additional information and specifications, write for new c cat. no. . circle no. on readers no. no. - . - tt ....... ! ?y. < it .d. r. e ;; a: g| y s . : .d ......... t .................... df| d f . 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"''"t'; m:::,s'k's no. no. . ii lab-line instruments, inc. designers and manufacturers lab-line plaza melrose park, illinois first in instruments serving science, industry, and education since service card s- this time takes on added significance for the following two reasons: i) interest within aaas. in addi- tion to the members of aaas who primarily identify with section p, there are no less than additional members who are on record as having more than passing interest in its affairs. ) there is much interaction be- tween societal problenms anid industrial scienice. here section p can create op- portunities for dialogue and contribute to solutions. in our world, beset by crises, our aspirations are outrunning our means of attaining them. the difference seems to be increasing-a situation not exact- ly conducive to world tranquillity. con- flicts abound. resource extraction, con- version processes, and the production of end-use items seem to interfere with the improvement and even with the maintenance of the quality of our so- cial and physical environment. we have already experienced such phe- nomena as the "environmental crisis" and the "energy crisis" with related "oil politics," reflecting highly complex in- ternational conflicts. we may be on the eve of an even more serious "world food crisis" with "food politics." in times past, science and technology have proved to be most effective "tools" in helping reduce the gap between what we want and what we can have. indus- try has been and is a major contributor to the development of these tools, as well as an effective user. it is also in- dustry that is at the interface between supply and demand and between the markets of society and the goods and services that it can produce. these vital interfaces, we feel, are worthy of much study and reflection. it should be evi- dent then that an active and effective section on industrial science or better yet an industrial science and technol- ogy section within the aaas would be in the best interest of all concerned. it could then conicentrate on the utility and application of not just science, but also technology, within an industrial context and the large social context. we have already embarked on the renaissance alluded to before. a re- alignment proposal has been mailed to the members of section p. mem- bers who are not among these but who would like to get involved in our ef- forts, please send a note to either of us in care of the aaas. gabor strasser chairmnan, section p robert l. stern secretary, section p science, vol. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ quo vadis industrial science? gabor strasser and robert l. stern doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the trademark of aaas. is a registeredscienceadvancement of science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for thescience by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ science magazine december vol science www.sciencemag.org c r e d it :c o u r t e s y o f r ic e u n iv e r s it y o f f ic e o f m e d ia r e la t io n s a n d i n f o r m a t io n r ichard errett smalley, who died on october after a -year fight with cancer, unself ishly used his stature and wisdom to inspire a worldwide nan- otechnology revolution. his breakthroughs, his inexhaustible enthusiasm for exciting young people about science, and his awak- ening the world to possible nanotech solu- tions to the energy crisis have all left an enduring legacy. in only years of apply- ing his powerful intellect to science and technology, his work led to entirely new types of materials and fields of study, revo- lutionary apparatus for scientific investiga- tions and commercialization, and a deep understanding of behavior on nano and molecular scales. along the way he shared the nobel prize in chemistr y for codiscovering the soccer-ball shaped c fullerene molecule. born in akron, ohio, on june , smalley’s interest in science began in his early teens as he and his mother collected single-cell organisms from a local pond and studied them with a microscope. he learned from his f ather how to b uild and f ix mechanical and electrical equipment and from his mother mechanical drawing, so that he could be more systematic in design work. many decades later, rick’s passion for creative design was still evident on his off ice walls—diagrams showing his most recent improvements on equipment for pro- ducing carbon nanotubes. although his con- tributions to physics and engineering were landmarks, chemistry was his first love. the detailed periodic table of the elements that he drew on rafters in the attic where he stud- ied as a youngster marked his early fascina- tion with chemistry. he pursued this love, from under- g raduate studies at hope college and t h e university of michigan to the shell chemical company, where he worked as a quality control chemist in a polypropylene plant. rick said, “these were fascinating days, involving huge volumes of material, serious real-world problems, with large financial consequences.” he learned about industrial-scale processes and the impor- tance of efficient catalysts, which were use- ful much later when he initiated scale-up of carbon nanotube synthesis. after years, he resumed academic studies and earned his ph.d. in from princeton university, focusing on the chemical physics of con- densed phase and molecular systems with thesis adviser elliott bernstein. during postdoctoral study with donald levy and lennard whar ton of the university of chicago, and later with daniel auerbach, rick helped develop a powerful technique: supersonic beam laser spectroscopy. as a result, chemical physi- cists can now drastically simplify the spec- troscopy of complex molecules. using t h e coldest par t of the expanding gas, researchers could achieve temperatures below k, thereby freezing the rotations of moderate-sized molecules and complexes. after joining the faculty of rice university in , smalley worked together with robert curl to produce a sequence of pio- neering advances applicable for making and characterizing very cold supersonic beams of large molecules, radicals, and atomic clusters having precisely known numbers of atoms. in august , smalley and curl were joined by harold kroto from the university of sussex for a short summer project to study interesting carbon cluster distribu- tions found by andrew kaldor at exxon using an apparatus constructed by smalley’s group. after a legendary late night of taping together cardboard cutouts of hexagons and pentagons on his kitchen table, using kroto’s insights into the importance of five- carbon rings, smalley presented the carbon “soccer ball” as the only sensible way that carbon atoms could be assembled to pro- duce the observed spectra. a new f ield of scientific investigation was thus born, and then fueled by a seemingly continuous bar- rage of exciting new results from both rick’s laboratory and others across the world, which showed the diversity of carbon cage types, how their production could be scaled up, the diverse ways they can be modif ied, and their novel physical and chemical properties. in , rick redirected much of his group’s work to carbon nanotubes, which can be viewed as cylindrical versions of the carbon cage molecules, and rick and his co-workers became leaders in the field. his experimental skills were again critical as his team developed the laser ablation and the high-pressure carbon monoxide processes for making single-walled carbon nanotubes. rapid worldwide scientif ic progress was assisted by rick’s providing access to these high-quality nanotubes, first through a non- prof it effort at rice university, and then through the successful company he founded in , carbon nanotechnologies, inc. many call rick the grandfather of nan- otechnology. he was the most cited author in nanotechnology in the last decade, and his pivotal scientif ic and technological breakthroughs have inspired worldwide commercialization effor ts. because of rick’s key role in creating the national nanotechnology initiative, he was the only academic invited to the november oval office signing ceremony. his vision of using nanotechnology to help solve the energy crisis and to improve health through nanomedicine is motivating governments to fund effective programs. many will dedi- cate themselves to a goal that rick focused upon during his last years of life: a carbon nanotube quantum wire cable much stronger than steel that would carry a cur- rent times as high as that carried by cop- per wire and weigh one-sixth as much. with his passing, the world lost a great intellect in chemistry, physics, and engi- neering, but we also lost a great advocate for science and technology and a great educator and mentor. robert curl said that “rick was a visionary, and his charisma and logic made those he worked with buy into the vision. rick convinced us that we could be better, stronger, and take more chances if we just tried. i hope that we don’t forget—then his legacy…will make a lasting transforma- tive difference.” in his humble way, rick simply said that science and life go on. . /science. p e r s p e c t i v e s r e t r o s p e c t i v e richard e. smalley ( – ) w. wade adams and ray h. baughman w. w. adams is at the center for nanoscale science a n d te c h n o l og y, r i c e u n i ve rs i t y, h o u s t o n , t x – , usa. e-mail: wade.adams@rice.edu r . h . b a u g h m a n i s a t t h e n a n o te c h i n s t i t u t e , university of texas at dallas, richardson, tx , usa. e-mail: ray.baughman@utdallas.edu published by aaas o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ richard e. smalley ( - ) w. wade adams and ray h. baughman doi: . /science. ( ), . science article tools http://science.sciencemag.org/content/ / / permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the is a registered trademark of aaas.sciencescience, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for the advancement ofscience © american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ population; a previous report, however, suggests it is around %. ° many of these unplanned pregnancies will be terminated; in our study the figure of % agrees with evidence to suggest that one in five pregnancies are terminated in the united kingdom. conclusion the confused medical awareness of which contra- ceptive methods are appropriate may partly explain why advice to women with sickle cell disease is often lacking. we cannot exclude a possible risk of crises and thrombotic episodes with the use of the combined contraceptive pill. despite this, we do not consider it to be contraindicated in this group of women as any complications should be balanced against the substantial risks of pregnancy. we feel that all methods of contraception may be considered in women with sickle haemoglobinopathies, though with appropriate caution. we gratefully acknowledge generous financial support from scar (sickle cell anaemia relief) and the invaluable cooperation of the north london haemoglobinopathy group and the sickle cell centres of north london. tuck sm, studd jww. pregnancy in sickle cell disease in the uk. brj obstet gynaecol ; : - . foster hw. contraceptives in sickle cell disease. south medj ; : - . evans dik. sickle cells and hormonal contraception. british journal of family planning ; o: - . perkinsrp.contraceptionforsicklers. nengl_med ; : . morrison jc. hemoglobinopathies and pregnancy. cgin obstet gynecol ; : - . louden n, ed. handbook of family planning. nd ed. london: churchill livingstone, . sergeant gr. sickle haemoglobin and pregnancy. bmj ; : - . petrou m, modell b, darr a, old j, kin e, weatherall d. antenatal diagnosis. how to deliver a comprehensive service in the united kingdom. ann n yacad sci ; : - . loukopoulos d, hadji a, papadakis m, karababa p, sinopoulou k, boussiou m, et al. prenatal diagnosis of thalassaemia and of the sickle cell syndromes in greece. ann n yacad sci ; : - . anionwu en, patel n, kanji g, renges h, brozovic m. counselling for prenatal diagnosis of sickle cell disease and thalassaemia major: a four year experience. jmed genet ; : . rowley pt, loader s, sutera cj, walden m, kozyra a. prenatal screening for haemoglobinopathies. i. a prospective clinical trial. am j hum genet ; : - . samuels-reid jh, scott rb, brown we. contraceptive practices and reproductive patterns in sickle cell disease. j natl med assoc ; : - . charache s, niebl jr. pregnancy and sickle cell disease. clin haematol ; : - . de ceulaer k, gruber c, hayes r, serjeant gr. medroxyprogesterone acetate. and homozygous sickle cell disease. lancet ;ii: - . freie hmp. sickle cell diseases and hormonal contraception. acta obstet gynecol scand ; : - . lutcher cl, milner pf. contraceptive-induced vascular occlusive events in sickle cell disorders-fact or fiction? clin res ; : a. greenwald jg. stroke in a woman with sickle cell trait taking oral contracep- toves. conn med ; : - . hargus ep, shearin r, colon ar. pulmonary embolism in a female adolescent with sickle cell trait and oral contraceptive use. am j obstet gynecol ; : - . haynes rl, dunn jm. oral contraceptives, thrombosis, and sickle cell haemoglobinopathies. jama ; : - . fleissig a. unintended pregnancies and the use of contraception: changes from to . bm ; : . smith t. unwanted pregnancies. bmj ; : . (accepted april ) why have child pedestrian death rates fallen? ian roberts injury prevention research centre, department of community health, university ofauckland, private bag , auckland, new zealand ian roberts, health research council trainingfellow bmj ; : - pedestrian injuries are a leading cause of childhood mortality and disability. over the past two decades in britain child pedestrian death rates have fallen despite large increases in traffic volume. in this paper roberts examines the likely reasons for this decline. he argues that neither prevention pro- grammes nor improvements in medical care are a plausible explanation and that the decline is most likely the result of a substantial reduction in children's traffic exposure. he believes, however, that restricting children's traffic exposure exacer- bates socioeconomic differentials in childhood mortality and denies children their right to mobility. roberts is convinced that one answer is for british transport policy to be aimed at providing mobility equitably rather than struggling to meet the ever increasing demands ofcar travel. between and in england and wales an average of children were killed each year on the roads as pedestrians. for every death around children required hospital admission for injuries.' pedestrian injuries were among the leading causes of childhood admission to intensive care facilities. between % and % of these children have severe head injuries and are likely to experience long term disability.' with the more widespread recognition of the public health importance of child pedestrian injuries in recent years several epidemiological studies have been mounted aimed at identifying modifiable risk factors. these studies have used case-control or cohort methods in an attempt to identify the factors which place some children at high risk of pedestrian injury." however, an effective public health response to the problem of child pedestrian injury demands that a second aetio- logical issue should be addressed. this concerns the identification of determinants of the incidence, attempting to understand why child pedestrian death rates change over time. answering this question is likely to be as important as identifying risk factors, because if the determinants of the incidence could be identified it might be possible to control them, with gains for the whole child population. over the past two decades child pedestrian death rates have fallen in many developed countries. in england and wales between and the pedes- trian mortality among children aged - years fell by %, and among children aged - years it fell by %. to gain an insight into why child pedestrian death rates have fallen changes in the potential deter- minants of the child pedestrian death rate must be considered. potential determinants ofchild pedestrian deaths the determinants of incidence are most readily identified when their prevalence changes abruptly. for this reason the effect of traffic volume on child pedestrian mortality was most evident during the energy crisis, when an increase in the price of petrol had a measurable effect on the growth in traffic volume. in new zealand government restrictions on car use in the aftermath of the energy crisis effectively arrested the growth in traffic volume for seven years, during which there was a - % reduction in child pedestrian mortality. before this the death rate had been increasing in parallel with increasing traffic volumes. that the rate fell, as opposed to levelling off in line with traffic volume, suggests that there were other processes operating, tending to reduce the mortality, but which became evident only when traffic bmj volume june o n a p ril b y g u e st. p ro te cte d b y co p yrig h t. h ttp ://w w w .b m j.co m / b m j: first p u b lish e d a s . /b m j. . . o n ju n e . d o w n lo a d e d fro m http://www.bmj.com/ volume was unchanging. in britain since the child pedestrian death.rate has fallen despite an almost exponential increase in traffic volume (fig ).' this implies' even mqre substantiwl changes in other, more powerful determinants of incidence. these changes have been particularly important for children aged - , for 'whom reductions in mortality have been most dramatic. pedestrian skills training it would be comfortng if there were evidence to' show that at least some, of the reduction in. child pedestrian mortality could be attributed"to pedestrian injury prevention programmes, but'this evidence is lacking. in britain the main thrust of preventive strategy has comprised efforts to improve childl pedes- trian behaviour through -pedestrian skills training programmes-for example, the green cross code.- however, data from evaluation studies suggest that these programmes are of limited, value.' some north american studies have claimed reductions in injury rates following pedestrian education programmes but evaluation in these studies 'was based on before and: after comparisons,-so that the apparent reductions may have been confounded by changes in the background rate." studies which have employed more rigorous- methods have concluded that even large efforts to improve pedestrian behaviour are rewarded by only small gains." furtiermore, as programmes have been aimed predominantly' at schioolchildren they cannot explain the large -reductioi in pedestrian mortality among preschool children. it therefore seems im- plausible that pedestrian education programmes have had a substantial effect on--child pedestrian mortality. in britain between and the number of police reported child pedestrian casualties fell by % but the number of deaths fell by /% (j broughton, transport research laboratory, personal communica- tion, ), suggesting that some ofthe decline in child pedestrian mortality may be due -to reduction in case fatality. these- data must ';be-viewed with caution;' however. child pedestrian- injuries aare significantly underreported -in p lice aciident databases, and' changes over time it casualty'numbers might simply reflect changes in the extent of underreporting.' furthermore, as children under have a higher case fatality rate posgily fthe apparent, overall reduction ain case fatality is- due to a change in the age distribution of injured childn, young ch n now maldng up a smaller- proportion of the total casualties." -if there has been a reduction in case fatality this may have resulted from a decrease in injury severity or fromn improve- fig z-lur own;, ,y l x lowry ments in medical care. regardless, the % decrease in casualty numbers implies that most of the reduction in child pedestrian mortality is due to a reduction in collisions between child pedestrians and motor vehicles. traffic exposure the most plausible explanation for the downward trend in child pedestrian mortality is that it reflects a decline in children's traffic exposure. as the volume of road traffic has increased streets have become more dangerous and increasingly children have been kept away fronr them.' until recently the only testimony was old photographs or paintings depicting towns and cities as they were before the heyday ofthe motorcar, in which children would often be seen playing in the street. the urban landscapes of l s lowry starkly portray the grime- and pollution of industrial england, but the street scenes convey a vivacity and a sense of both safety and 'community which is absent today (fig ). a recent british study which examined changes in children's independent mobility over the past two decades has provided compelling evidence for a decline in children's traffic exposure. ' for example, it was found that whereas in , % of and year old english children were allowed to travel to school unaccompanied, in the -figure was /o. the principal reason parents gave for their reluctance to allow their children to travel 'unaccompanied was traffic danger. similarly, the age at which children ,receive parental "licence" to cross roads has increased considerably, and there was a pronounced decline in the proportion of children who were allowed to cross roads alone in compared with . these findings might explain why the decline in pedestrian mortality has been least in the - year age group, as it would be more difficult for parents to limit the traffic exposure of older children.' moreover, a study in manchester found that the pedestrian injury rate among children aged - had increased by % bet-ween and .' t'.he importance of traffic exposure is also apparent in case centred epidemiological studies. a north american case-control study found that the absence of a play area adjacent to the home was associated with a fivefold increased risk of pedestrian injury (odds ratio - ; % confidence interval * to . ). the effect of this risk factor is likely to be mediated through the greater traffic exposure of children who have fewer altematives to playing in the street. indices of safety -'a consideration of children's traffic exposure has been the missing element in virtually all of the political deliberations on road safety for children over the past two decades.' as a result the effect on child pedestrian > safety of the massive increase in traffic volume which has taken place over this period has been completely obscured. in the absence of an exposure measure -thepedestrian injury rate has been used as an index o.af- safety. the fallacy' inherent in this reasoning is -jopparent from a consideration of age specific child pedesinan injury rates. h in the absence of'information on traffic exposure, ! using pedestrian injury hospitalisation rates as a measure of safety would lead us to conclude that a year old child ( / admissions/year) is safer in a traffic setting than a year old ( - / /year) - (unpublished observations, new zealand data). in o contrast, for motor vehicle occupants the established ; safety measure is deaths per vehicle mile travelled, the | rationale for which was given in the motor vehicle safety- position paper of a recent american injury control conference-"highway transportation has been bmj volume une traffic volume o- fatality rate . q~~~~~~ e ~ year fig -childpedestnan death rates and traffic volume in britain - . (sources- fatality rates: office of population censuses and surveys, unpublished data, traffic volume: transpoq research laboratory, unpublished data) -' o n a p ril b y g u e st. p ro te cte d b y co p yrig h t. h ttp ://w w w .b m j.co m / b m j: first p u b lish e d a s . /b m j. . . o n ju n e . d o w n lo a d e d fro m http://www.bmj.com/ created to facilitate mobility and mobility is of value." strategies which reduce the need for car travel or substitute car travel with safer forms of transport would substantially reduce population death rates. ' thus deaths per vehicle mile travelled clearly signals that improvements in safety must not limit car use. because children's mobility is not valued the decline in child pedestrian mortality has taken place at its expense. implications oflimiting child mobility as a means of preventing child pedestrian injuries limiting children's traffic exposure has powerful disad- vantages. in particular, it will exacerbate the striking socioeconomic inequalities in child pedestrian injury morbidity and mortality that already exist. both british and overseas studies have shown that poor children have a risk of pedestrian injury some three times greater than the least poor, and census area unemployment has been shown to be strongly corre- lated with census area child pedestrian injury rates. - indeed, pedestrian injuries are a major contributor to socioeconomic differentials in childhood mortality. as one third of british households do not have access to a car escorting children is likely to be far more difficult for some families. poor children are likely to have fewer alternatives to playing in the street, and super- vising children will be far more demanding in single parent families. the british epidemiologist geoffrey rose has argued that in disease prevention two broad types of strategy can be distinguished: those that restore biological normality and those that take us further from the conditions for which we were genetically adapted. restoration of biological normality is gener- ally safe whereas the consequences of moving away from our biological condition are often unknown and the potential for harm may easily be overlooked. in this context limiting children's independent mobility is a clear departure from biological normality. changes in childhood exercise patterns may impact on children's cardiovascular health, and with children increasingly confined to the home because of traffic danger height- ened family tensions may erupt as family violence. historically, public health investigators have been slow to recognise the importance of such social pro- cesses and as a result have witnessed the waxing and waning of mortality from many diseases, although often ignorant of the reasons and powerless to inter- vene. the future traffic volume is expected to increase by % by the year , and no doubt the rampant individualism of free market economic policies will ensure that this prophecy is realised. the increase in traffic volume will inevitably result in a more hostile urban living environment for children. more fortunate children will reap the benefits of increased car travel while being largely immune from the accompanying dangers. but for the increasing number of british children living in poverty paramount among threats to health are vehicles that most will only ever have the opportunity to steal. further reductions in children's independent mobility may offset the increase in danger but already child pedestrian death rates seem to be levelling off and in some countries-for example, the united states- may be rising. it must be recognised that unfettered market forces will inevitably disregard the rights of the more vulner- able members in society and that a more collective social responsibility is appropriate. british transport policy should aim to provide mobility equitably and for all people rather than continually struggle to meet the ever increasing needs of car users. of course, challenging the dominant position of the private passenger car in the transport system will inevitably confront powerful vested interests. the car lobby is strong and well organised.' the lessons leamt from previous public health struggles with pecuniary power will be invaluable. mobility is of value but so is equity. the transport system of the future should embrace both of these concems. rivara fp. child pedestrian injuries in the united states. am j dis child ; : - . roberts i, streat s, judson j, norton r. critical injuries in paediatric pedestrians. nzmedj ; : - . roberts i, norton r, hassall i. child pedestrian injury - . n z med j ; : - . mueller ba, rivara fp, shyh-mine l, weiss ns. environmental factors and the risk of childhood pedestrian-motor vehicle collision occurrence. amjepidemiol ; : - . pless ib, verreault r, tenina s. a case control study of pedestrian and bicyclist injuries in childhood. amj public health ; : - . pless ib, peckham cs, power c. predicting traffic injuries in childhood: a cohort analysis. j pediatr ; : - . rose g. sick individuals and sick populations. int epidemiol ; : - . roberts i. intemational trends in pedestrian injury mortality. arch dis child ; : - . roberts i, marshall r, norton r. child pedestrian mortality and traffic volume in new zealand. bmj ; : . organisation for economic co-operation and development. traffic safety of children. paris: oecd, . preusser df, blomberg rd. reducing child pedestrian accidents through public education.j ournal ofsafety research ; : - . fortenberry jc, brown db. problem identification, implementation and evaluation of a pedestrian safety programme. accid anal prev ; : - . rivara fp, booth cl, bergman ab, rogers lw, weiss j. prevention of pedestrian injuries to children: effectiveness of a school training program. pediatrics ; : - . maas mw, harris s. police recording of road accident inpatients. accid anal i ev ; : - . pitt r, guyer b, hsieh c, malek m. the severity of pedestrian injuries in children: an analysis of the pedestrian injury causation study. accid anal rev ; : - . adam jg. risk homeostasis and the purpose of safety regulation. ergonomics ; : - . hillman m, adams j, whitelegg j. one false move: a study of children's independent mobility. london: policy studies institute, . quick a. unequal risks: accidents and social policy. london: socialist health association, . preston b. child pedestrian casualties with special reference to casualties on the joumey to or from school in manchester and salford, england. accidanalprev ; : - . us department of health and human services. third national injury control conference. position papers. washington, dc: us govemment printing office, . trinca gw, johnston ir, campbell bj, haight fa, knight pr, mackay gm, et al. reducing traffic injury: a global challenge. melboume: royal australasian college of surgeons, . office of population censuses and surveys. occupational mortality: child supplement. england and wales - , - . london: hmso, . (series ds no .) pless ib, verreault r, arsenault l, frappier j, stulginskas j. am j public health ; : - . dougherty g, pless ib, wilkins r. social class and the occurrence of traffic injuries and deaths in urban children. can jpublic health ; : - . roberts i, marshall r, norton r, borman b. an area analysis of child injury morbidity in auckland. j pediatr child health ; : - . rose g. strategy of prevention: lessons from cardiovascular disease. bmj ; : - . rose g. reflections on the changing times. bmj ; : - . godlee f. children harmed by traffic fumes. bmj ; : . spencer nj. child poverty and deprivation in the uk. arch dis child ; : - . beaglehole r. science, advocacy and health policy: lessons from the new zealand tobacco wars.j public health policy ; : - . (accepted march ) correction how can we best prolong life? benefits ofcoronary risk factor reduction in non-diabetic and diabetic subjects a typesetting error occurred in table iv of this paper by john s yudkin ( may, pp - ). in the bottom line of the table (lowering systolic blood pressure mm hg) the entry in the second column of figures is wrong: it should read - (- to - ), not - (- to - ). bmj volume june o n a p ril b y g u e st. p ro te cte d b y co p yrig h t. h ttp ://w w w .b m j.co m / b m j: first p u b lish e d a s . /b m j. . . o n ju n e . d o w n lo a d e d fro m http://www.bmj.com/ current studies on myofascial pain syndrome ta-shen kuan, md, ms corresponding author ta-shen kuan, md, ms department of physical medicine and rehabilitation, college of medicine, national cheng-kung university, sheng-li road, tainan, , taiwan. e-mail: kuan@mail.ncku.edu.tw current pain & headache reports , : – current medicine group llc issn - copyright © by current medicine group llc recent studies have clarifi ed the nature of myofascial trigger points (mtrps). in an mtrp region, multiple hyperirritable loci can be found. the sensory com- ponents of the mtrp locus are sensitized nociceptors that are responsible for pain, referred pain, and local twitch responses. the motor components are dysfunctional endplates that are responsible for taut band formation as a result of excessive acetylcho- line (ach) leakage. the concentrations of pain- and infl ammation-related substances are increased in the mtrp region. it has been hypothesized that excessive ach release, sarcomere shortening, and release of sensitizing substances are three essential features that relate to one another in a positive feedback cycle. this mtrp circuit is the connection among spinal sensory (dorsal horn) neurons responsible for the mtrp phe- nomena. recent studies suggest that measurement of biochemicals associated with pain and infl amma- tion in the mtrp region, the sonographic study of mtrps, and the magnetic resonance elastography for taut band image are potential tools for the diagnosis of mtrps. many methods have been used to treat myofascial pain, including laser therapy, shockwave therapy, and botulinum toxin type a injection. introduction myofascial pain syndrome (mps) has been widely accepted as a clinical entity based upon recent studies on myofascial trigger points (mtrps) [ – ]. mps is defi ned as a regional pain syndrome characterized by muscle pain caused by mtrps [ , ]. mps may include a regional muscle pain syndrome of any soft tissue origin that is associated with muscle tender points or trigger points [ ]. in skeletal muscle, a tender point can be an mtrp if it locates in the endplate zone with all characteristics of an mtrp, such as taut band, referred pain, and local twitch response (ltr) [ ]. because mps is caused by mtrps, this article concentrates on the research on mtrps. studies on the mtrp region the concept of multiple sensitive loci in an mtrp region suggested by hong and simons [ ] has been well supported by human and animal studies (fig. ). an mtrp locus contains a sensory component and a motor component. at the sensory locus, pain, referred pain, and ltr can be elicited when this locus is mechanically stimulated with adequate pressure. this locus has been defi ned as a sensi- tive locus or ltr locus. at the motor locus, spontaneous electrical activity ([sea], including endplate noise [epn] and endplate spikes) can be found in electromyographic (emg) recordings. this motor locus has been defi ned as an active locus, sea locus, or epn locus. an ltr locus is a sensitized nociceptor (free nerve ending) [ ], and an sea locus is a dysfunctional endplate [ , – ]. an sea locus is in the closed vicinity of an ltr locus. they interact mutually for the formation of a taut bend. stimulation of an ltr locus can elicit pain, referred pain (due to central sensitization), and ltr (via spinal cord refl ex). hong et al. [ ] reported that a nerve ending (nocicep- tor) could be frequently found at the site where ltr can be elicited. kuan et al. [ •] has further confi rmed that by injecting horseradish peroxidase into the nociceptors, subsequent spreading to the dorsal ganglia and spinal cord dorsal horn region occurred. sea recorded from an mtrp region is actually abnor- mal endplate potentials [ , , ]. simons [ ] suggested that the occurrence of epn indicates excessive leakage of acetylcholine (ach) in the endplate region based on extensive reviews of old physiological literature. this was further supported by an animal study showing that epns recorded in the mtrp region were suppressed after the injection of botulinum toxin type a (btx-a) [ ]. the leakage of ach molecules can cause focal contracture of sarcomeres to form a contraction knot [ ]. in several stud- ies, simons [ , , ] discussed an energy crisis hypothesis to explain the formation of a taut band. the author pos- tulated that excessive ach release, sarcomere shortening, and release of sensitizing substances are three essential i fibromyalgia/myofascial pain features that relate to one another in a positive feedback cycle. an increased ach release in the neuromuscular junction (motor endplate) can cause an increase of the muscle fi ber tension (taut band) that contains an mtrp, and subsequently can cause energy crisis due to increased metabolism and local ischemia with hypoxia. in this situ- ation, secretion of sensitizing substances can be increased to cause pain. the sensitizing substances can further cause abnormal ach release to create a vicious cycle [ ]. an animal study demonstrated that sea persisted after transection of peripheral nerve and a high-level spi- nal cord [ ]. kuan et al. [ ] also found no increase in neuromuscular jitter in the myofascial trigger spot region based on a single-fi ber emg study. it appears that the excessive leakage of ach in the endplate is not immedi- ately controlled by nervous system. these two fi ndings support the hypothesis that energy crisis in the mtrp region is a focal reaction and not related to neural con- trols. however, in another recent single-fi ber emg study, chang et al. [ ••] found the evidence of degeneration in motor nerve endings in the mtrp region. further study is required to clarify if any motor nerve lesion is involved in the pathogenesis of an mtrp. in recent studies by shah’s group [ , ••] using a microanalytic technique to measure biochemicals (asso- ciated with pain and infl ammation) at the mtrp region of upper trapezius muscle in subjects identifi ed as active (neck pain and mtrp), latent (no neck pain but with mtrp), or normal (no neck pain, no mtrp) have demon- strated increases in concentrations of all analytes in active subjects compared with the latent or normal ones. these fi ndings strongly support simons’ integrated hypothesis of energy crisis [ , ]. they also found remarkable eleva- tion of biochemicals during the ltr. however, substance p and calcitonin gene–related peptide (cgrp) were the only two analytes for which concentrations during the recovery period after the ltr were signifi cantly below the baseline concentrations [ ]. this interesting fi nd- ing could explain the immediate relief of pain (reduced substance p and cgrp) after eliciting ltrs during mtrp injection. however, the mechanism is unclear. recent studies have demonstrated that the irritabil- ity of an mtrp is proportionate to the prevalence [ ••] and the amplitude [ ] of epn recorded from that mtrp region. the assessment of sea (including epn) in an mtrp region has been used for the evaluation of the effec- tiveness of a certain therapeutic method [ , – ]. studies on the spinal cord mechanism referred pain and ltr are two important characteristics of mtrps. both are mediated via the spinal cord mechanism, based on recent human and animal research studies [ , ]. in animal studies on the referred pain from a muscle to other distant ones, mense and simons [ ] demonstrated that the elicited referred pain is secondary to the unmask- ing of formerly ineffective synaptic connections among neurons corresponding to different receptive fi elds. a strong noxious stimulus can send the impulse to the cor- responding dorsal horn neuron and induce it to release substance p and cgrp, which diffuse to other dorsal horn neurons and increase the effi cacy of silent synaptic connections as a consequence of central sensitization in the spinal cord level [ ]. in a human study, referred ten- derness could be elicited not only from the active mtrp, but also from a latent mtrp region or even normal muscle tissues [ ]. however, a higher pressure was required to elicit referred pain from a latent mtrp or normal muscle tissues than from an active mtrp. the pressure required to elicit referred pain from a compressed site is propor- tionate to the degree of irritability [ ]. ltrs can be recorded electromyographically from a taut band that contains an mtrp when this mtrp is mechanically stimulated with a high pressure [ , ]. in an animal study, ltrs could also be elicited when the mtrp was mechanically stimulated, and could only be perfectly recorded in the taut band but not other sites [ ]. it was further demonstrated that the ltrs could be recorded from a muscle only if the innervated nerve was intact with a complete connection with the spinal cord [ ]. however, ltrs recorded from a mus- cle subsided transiently after a complete transection figure . multiple loci in an mtrp. ltr—local twitch response; mtrp—myofascial trigger point; sea—spontaneous electrical activity. current studies on myofascial pain syndrome i kuan i of the spinal cord at a level higher than that providing innervation to that muscle, but recovered to nearly the original level after the spinal shock period [ ]. these fi ndings strongly suggested that ltr is mediated via a spinal cord refl ex [ , ]. based on these fi ndings, the neural network with connections among dorsal horn neurons related to an mtrp was defi ned as an mtrp circuit [ , ]. an mtrp circuit corresponding for a certain mtrp can also send nerve branches to connect with the other mtrp circuit corresponding to other mtrps. a latent mtrp can become active if stimuli from peripheral sites are strong enough to trigger the mtrp circuit of this latent mtrp. most adults have latent mtrps in most skeletal muscles that can become active in response to any related lesion in another site. a recent study found no latent mtrps in children under the age of year [ ••]. it appears that mtrp circuits in the spinal cord develop in later life when the child is growing up. diagnosis of myofascial pain the diagnosis of mtrps depends on manual palpation and clinical judgement. however, manual palpation has been considered to be an unreliable technique [ ]. special training is usually required to obtain a common agreement in the judgement of palpation criteria [ ]. it has been suggested that spot tenderness, taut band, and pain recognition are the three important criteria for the diagnosis of mtrps, and referred pain and ltrs are the confi rmatory signs for mtrp diagnosis [ ]. measurement of biochemicals associated with pain and infl ammation in the mtrp region [ ], the sono- graphic study of mtrps [ ], and the magnetic resonance elastography for taut band image [ ••] are potential tools for the diagnosis of mtrps. however, some of these tools are relatively expensive at this time. treatment of mtrps hong [ , ] defi ned mps as any pain phenomenon due to activation of latent mtrps as a consequence of certain pathological conditions, including chronic repetitive minor muscle strain, poor posture, systemic diseases, or neuromusculoskeletal lesions (eg, strain, sprain, enthe- sopathy, bursitis, arthritis, vertebra disc lesion). the underlying pathological lesions associated with activa- tion of mtrps are usually found in other regions remote to the activated mtrp due to central sensitization, but can also be due to overactivity of a muscle because of peripheral sensitization [ , ]. however, mtrps due to muscle overactivity can be easily inactivated after avoidance of overuse or inappropriate use. persistent or recurrent mtrps are usually related to remote lesions. it has been strongly suggested that the most important strategy to treat mps is to identify and treat the under- lying etiological lesions appropriately [ , , ]. in certain situations, treatment (inactivation) of active mtrps is necessary. inactivation of mtrps may be impor- tant in cases of intolerable pain, pain or discomfort that interferes with functional activities, persistent pain after elimination of the underlying etiological lesion, and fail- ure in identifying or treating the underlying pathology. release of muscle tightness due to taut band may improve the local circulation to facilitate the healing process of the underlying etiological lesion. by either treating active mtrps or their underlying pathology, conservative treat- ment should be performed before more aggressive therapy [ , ]. any perpetuating factor that may cause persistent existence or recurrence of active mtrps should also be eliminated, and adequate education and home programs should be provided to patients so that recurrent or chronic pain can be avoided [ , ]. the management of myofascial pain due to mtrps has been extensively described [ , , , , ]. the commonly applied mtrp therapies include intermittent cold and stretch (spray and stretch), deep pressure soft tissue massage, trigger point pressure release, postisometric relaxation, manipulation, thermotherapy (usually combined with oth- ers), ultrasound therapy [ ], electrotherapy, and needling (mtrp injection, dry needling, or acupuncture) [ , , ]. laser therapy has also been used to treat mtrps. snyder- mackler et al. [ ] noted signifi cant pain reduction and an increase in skin resistance after laser therapy; therefore, they suggested that the effectiveness was sympathetically mediated. the pain-relieving effect of laser treatment has been proposed by one or a combination of the following mechanisms: circulation enhancement, collagen prolifera- tion, peripheral nerve stimulation, an anti-infl ammatory effect, and direct analgesic effect [ ]. a recent animal study demonstrated a decrease of epn prevalence (related to mtrp irritability) after laser treatment [ ]. shockwave therapy is a newly developed device for treating mtrps [ ]. however, the mechanism in treating mtrps is also still unclear. combination of various methods is frequently applied in treating myofascial pain. mtrp injection with btx-a has been recommended to treat mtrps [ , ]. however, some recent studies found no signifi cant benefi t from btx-a injection compared with dry needling [ , ] or bupivacaine injection [ ]. consid- ering the cost of btx-a, it may not be used routinely. the most likely mechanism of pain relief by needle stimulation is hyperstimulation analgesia [ ]. the strong pressure stimulation to the mtrp loci (nociceptors) can provide very strong neural impulses to the dorsal horn cells in the spinal cord, which may then break the vicious cycle of the mtrp circuit [ , ]. conclusions recent basic and clinical studies on both animal and human subjects have made the pathophysiology of mtrps much better understood. each mtrp contains many basic units of an mtrp, the mtrp locus. each i fibromyalgia/myofascial pain mtrp locus consists of a sensory component (a sensitive locus; an ltr locus) and a motor component (an active locus; a sea locus). the pathogenesis of mtrps is prob- ably related to an integrative mechanism in the spinal cord in response to sensitized nociceptors (sensory loci) associated with dysfunctional endplates (active loci). with current knowledge of the pathogenesis of mtrps, we can keep making progresses in developing new and effective therapies for the management of mps. disclosure no potential confl ict of interest relevant to this article was reported. references and recommended reading papers of particular interest, published recently, have been highlighted as: • of importance •• of major importance . hong cz, simons dg: pathophysiologic and electrophysi- ologic mechanism of myofascial trigger points. arch phys med rehabil , : – . . simons dg: clinical and etiological update of myofascial pain from trigger points. j musculoskelet pain , : – . . simons dg, travell jg, simons ls: travell & simons’s myofascial pain and dysfunction: the trigger point manual, vol , edn . baltimore: williams & wilkins; . . mense s, simons dg: muscle pain: understanding its nature, diagnosis, and treatment. philadelphia: lippincott williams & wilkins; . . hong cz: algometry in evaluation of trigger points and referred pain. j musculoskelet pain , : – . . hong cz, chen jt, chen sm, et al.: histological fi ndings of responsive loci in a myofascial trigger spot of rabbit skeletal muscle from where localized twitch responses could be elicited (abstract). arch phys med rehabil , : . . simons dg: do endplate noise and spikes arise from normal motor endplates? 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rehabil , : – . . simons dg, dexter jr: comparison of local twitch responses elicited by palpation and needling of myofascial trigger points. j musculoskelet pain , : – . . hong cz, torigoe y: electrophysiologic characteristics of localized twitch responses in responsive bands of rabbit skeletal muscle fi bers. j musculoskelet pain , : – . . hong cz, torigoe y, yu j: the localized twitch responses in responsive bands of rabbit skeletal muscle fi bers are related to the refl exes at spinal cord level. j musculoskelet pain , : – . . hong cz: myofascial pain therapy. j musculoskelet pain , : – . . hong cz: treatment of myofascial pain syndrome. curr pain headache rep , : – . .•• kao mj, han ti, kuan ts, et al.: myofascial trigger points in early life. arch phys med rehabil , : – . this article extended our study of myofascial trigger points to the infant (less than year old). it was important for studying the development of myofascial trigger points. current studies on myofascial pain syndrome i kuan i . myburgh c, larsen ah, hartvigsen j: a systemic, critical review of manual palpation for identifying myofascial trigger points: evidence and clinical signifi cance. arch phys med rehabil , : – . . gerwin rd, shannon s, hong cz, et al.: identifi cation of myofascial trigger points: interrater agreement and effect of training. pain , : – . . gerwin rd, duranleau d: ultrasound identifi cation of the myofascial trigger point [letter]. muscle nerve , : – . .•• chen q, bensamoun s, basford jr, et al.: identifi cation and quantifi cation of myofascial taut bands with magnetic resonance elastography. arch phys med rehabil , : – . this article describes a new technique, magnetic resonance elastography, to image the existence of the taut band in the myofascial trigger point. . chen sm, chen jt, kuan ts, et al.: decrease in pressure pain thresholds of latent myofascial trigger points in the middle fi nger extensors immediately after continuous piano practice. j musculoskelet pain , : – . . kawakita k, itoh k, okada k: experimental model of trigger points using eccentric exercise. j musculoskelet pain , : – . . gerwin r: differential diagnosis of trigger points. j muscu- loskelet pain , : – . . gerwin rd: the management of myofascial pain syndromes. j musculoskelet pain , : – . . srbely jz, dickey jp: randomized controlled study of the antinociceptive effect of ultrasound on trigger point sensitiv- ity: novel applications in myofascial therapy? clin rehabil , : – . . hong cz: lidocaine injection versus dry needling to myofascial trigger point: the importance of the local twitch response. am j phys med rehabil , : – . . snyder-mackler l, bork c, bourbon b, et al.: effect of helium-neon laser on musculoskeletal trigger points. phys ther , : – . . bauermeister w: the diagnosis and treatment of myofascial trigger points using shockwaves. j musculoske pain , (suppl ): . . cheshire wp, abashian sw, mann jd: botulinum toxin in the treatment of myofascial pain syndrome. pain , : – . . wheeler ah, goolkasian p, gretz ss: a randomized, double-blind, prospective pilot study of botulinum toxin injection for refractory, unilateral, cervicothoracic, paraspi- nal, myofascial pain syndrome. spine , : – . . kamanli a, kaya a, ardicoglu o, et al.: comparison of lidocaine injection, botulinum toxin injection, and dry needling to trigger points in myofascial pain syndrome. rheumatol int , : – . . lew hl, lee eh, castaneda a, et al.: therapeutic use of botulinum toxin type a in treating neck and upper-back pain of myofascial origin: a pilot study. arch phys med rehabil , : – . . graboski cl, gray ds, burnham rs: botulinum toxin a versus bupivacaine trigger point injections for the treatment of myofascial pain syndrome: a randomized double blind crossover study. pain , : – . . melzack r: myofascial trigger points: relation to acupuncture and mechanism of pain. arch phys med rehabil , : – . << /ascii encodepages false /allowtransparency false 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/usedocumentprofile /untaggedrgbhandling /usedocumentprofile /usedocumentbleed false >> ] >> setdistillerparams << /hwresolution [ ] /pagesize [ . . ] >> setpagedevice making sense of low oxygen sensing making sense of low oxygen sensing julia bailey-serres , takeshi fukao , daniel j. gibbs , michael j. holdsworth , seung cho lee , francesco licausi , , pierdomenico perata , laurentius a.c.j. voesenek , and joost t. van dongen center for plant cell biology, department of botany and plant sciences, university of california, riverside, ca - , usa division of plant and crop sciences, school of biosciences, university of nottingham, loughborough le rd, uk max planck institute of molecular plant physiology, am muehlenberg , potsdam-golm, germany plantlab, institute of life sciences, scuola superiore sant’anna, piazza martiri della libertà , pisa, italy plant ecophysiology, institute of environmental biology, utrecht university, padualaan , ch utrecht, the netherlands center for biosystems genomics, pb wageningen, the netherlands review glossary anoxia: absence of oxygen. direct oxygen sensing: sensing of oxygen via its molecular interaction with a ligand (i.e. enzyme, protein, chemical compound) that results in an effect of cellular consequence. hypoxia: oxygen levels below normoxia; the term ‘hypoxic’ is often used to describe a situation where molecular oxygen is still present, but its level has significantly decreased below . %; cellular oxygen status may be hypoxic or anoxic dependent upon duration, location and metabolic activity. hypoxia-responsive genes: genes with transcripts differentially regulated in response to conditions with a low oxygen component. indirect oxygen sensing: sensing of change in homeostasis that is a consequence of oxygen deprivation (i.e. change in atp, adp, amp, other metabolite, ca + , ros, ph) that results in an effect of cellular consequence. normoxia: typically . % oxygen at atm and c. submergence: waterlogging and partial to complete immersion of aerial system. plant-specific group vii ethylene response factor (erf) transcription factors have emerged as pivotal regulators of flooding and low oxygen responses. in rice (oryza sativa), these proteins regulate contrasting strategies of flooding survival. recent studies on arabidopsis thaliana group vii erfs show they are stabilized under hypoxia but destabilized under oxygen-replete conditions via the n-end rule pathway of targeted proteolysis. oxygen- dependent sequestration at the plasma membrane maintains at least one of these proteins, rap . , under normoxia. remarkably, sub a, the rice group vii erf that enables prolonged submergence tolerance, appears to evade oxygen-regulated n-end rule degradation. we propose that the turnover of group vii erfs is of eco- logical relevance in wetland species and might be ma- nipulated to improve flood tolerance of crops. improved crop survival of floods is needed based on conservative expectations of human population growth, the maintenance of international food security will require a doubling of agricultural productivity in the next two decades [ ]. this challenge is exacerbated by severe weather events associated with climate change such as floods, which have occurred with increasing fre- quency across the globe over the past six decades (figure ). however, improvement of crop resilience to water extremes can be accomplished by harnessing natu- ral genetic diversity in breeding programs. an example of this is the use of the rice submergence a (sub a) gene, which confers prolonged tolerance to submergence (see glossary) [ ]. the effective sub a- allele was iso- lated from an eastern indian landrace and has been returned to farmers in high-yielding varieties [ ]. this new ‘sub rice’ promises to help stabilize harvests in rain- fed floodplains, which represent % of rice acreage world- wide [ ]. the task remains to improve flooding tolerance of other crops. recent comparative studies within and be- tween species have greatly enhanced our understanding of mechanisms that facilitate survival of distinct flooding regimes (table ). with new insights into low oxygen sensing and response mechanisms we are optimistic that effective means to lessen crop devastation by flooding can be extended beyond rice paddy fields. corresponding author: bailey-serres, j. (serres@ucr.edu) - /$ – see front matter � elsevier ltd. all rights reserved. doi: . /j.tplants. oxygen deprivation is a frequent component of flooding stress a key feature of flooding events is the change in levels of three gases, o , co and ethylene, due to a near reduction in their diffusion in water relative to air [ – ]. the flooding of root systems – a condition termed waterlogging – has little or no impact in semi-aquatic species such as rice that constitutively form gas conduits (i.e. aerenchyma) between submerged and aerial organs. however, if plants lack gas conduits or lose oxygen from roots, waterlogging rapidly reduces the oxygen concentra- tion within cells [ – ]. the presence of aerobic microbes in the soil can further exacerbate the stress. when both the root and aerial portions of a plant are whelmed by water – a condition termed submergence – cellular oxygen levels can also decline from normoxia. the degree of oxygen deficien- cy (hypoxia/anoxia) depends on multiple factors including replenishment of oxygen through photosynthesis, inward diffusion from the water layer and cellular consumption of oxygen through metabolic activity. severe oxygen defi- ciency compromises mitochondrial respiration [ , ] and leads to an insufficiency in atp for energy demanding processes [ , – ]. however, plants can adjust to this energy crisis through increased substrate level atp pro- duction (figure ). this is accomplished by catabolism of soluble sugars and in some species or cell types starch [ ]. typically, the increase in glycolytic flux is coupled with regeneration of nad+ by fermentation of pyruvate to waterlogging: flooding of root system. . . trends in plant science, march , vol. , no. mailto:serres@ucr.edu http://dx.doi.org/ . /j.tplants. . . america africa oceania europe number of flood events per decade asia trends in plant science figure . numbers of floods have increased in each of the past six decades across the globe. graphs show the number of floods classified as a disaster in the international disaster database of the university of louvain, belgium for the period from through by geographical region [ ]. events include river or coastal floods, rapid snow melts, heavy rainfall and other occurrences that caused significant social or economic hardship. adapted from a millennium ecosystem assessment map (http:// maps.grida.no/go/graphic/number-of-flood-events-by-continent-and-decade-since- ). review trends in plant science march , vol. , no. ethanol via pyruvate decarboxylase and alcohol dehydro- genase (adh). because ethanol diffuses out of cells into the external milieu, its production depletes the plant’s carbon reserves. therefore, metabolism of pyruvate to alanine provides an alternative, non-detrimental end product of anaerobic metabolism that is observed in a number of species [ , ]. this includes the generation of -oxoglutarate as a coproduct, which can be further metabolized to succinate, via the tca cycle enzyme succi- nate coa ligase (scs), thereby providing additional atp per molecule of sucrose metabolized. to keep these reac- tions running, the oxidation of nadh in the mitochondrial matrix is guaranteed by reduction of oxaloacetate via the reversed tca cycle reaction catalyzed by malate dehydro- genase [ , ]. the malate produced is probably further converted to fumarate and succinate [ ], the latter of which could be exported from hypoxic tissue to the aerated parts of the plant. at least in tubers of potato (solanum tuberosum), hypoxia stimulates a rearrangement of the mitochondrial respiratory supercomplexes that enhances regeneration of nad+ by the alternative nad(p)h dehy- drogenases [ ]. even though the efficiency of hypoxic atp production is low compared to aerobic oxidative phosphorylation, it allows cells to survive as long as carbohydrate substrate remains available. cell death only becomes inevitable when there is insufficient energy for exclusion of protons to the apoplast to prevent membrane depolarization and to maintain a near neutral cytosolic ph [ , , ]. avoidance of the severe energy crisis associated with low oxygen stress requires economization of atp consumption. means to this end include energy efficient sucrose catabolism through sucrose synthase [ ], the preferential use of ppi-dependent enzymes [ ], constrained catabolism of storage compounds such as starch, lipid and protein [ ], metabolic compartmentalization [ ], reduced protein synthesis [ ], increased production of heat shock proteins as molecular chaperones [ ] and adoption of the k+-gra- dient to energize membrane transport [ ]. plant survival of waterlogging or submergence also depends on their ability to limit or endure oxidative stress, which occurs during the transition from normoxia to anoxia as well as upon de-submergence [ – ]. ethylene initiates submergence survival strategies in rice and wetland species recent work has exposed mechanisms of response to sub- mergence that center on growth management. notable are two antithetical survival strategies displayed by both wild and domesticated species. for example, deepwater rice, cultivated to cope with slowly advancing floods, expends energy reserves in the elongation of internodal regions that are underwater to maintain photosynthetic tissue above the air–water interface [ , ]. similarly, the wetland dicot rumex palustris, which is well adapted to shallow but prolonged floods, reorients and extends petioles to elevate leaves above the surface of floodwaters [ , ]. how- ever, this ‘submergence escape’ strategy is unsuccessful if energy reserves are exhausted before escape of the deluge. in wetland species capable of surviving transient floods (e.g. rumex acetosa) [ ] and submergence tolerant sub rice [ ], a ‘quiescence strategy’ minimizes energy expen- ditures for growth until de-submergence. the genetic determinants and hormonal signaling path- ways that underlie the two flooding survival strategies have been identified. in rice, both strategies utilize the phytohormone ethylene and ethylene response factor (erf) transcription factors. combined physiological and molecular dissection of submergence responses in rice and r. palustris has yielded a model in which a buildup of ethylene in submerged organs initiates a hormonal signal- ing cascade that reduces the antagonism between abscisic http://maps.grida.no/go/graphic/number-of-flood-events-by-continent-and-decade-since- http://maps.grida.no/go/graphic/number-of-flood-events-by-continent-and-decade-since- table . factors that contribute to survival of flooding or oxygen deprivation condition species comparison acclimation or survival response causal factors refs submergence (partial) rice (oryza sativa ssp. indica) deepwater to non-deepwater cultivars; sk and sk transgenics rapid underwater internode elongation; escape strategy sk , sk , ethylene, ga, aba [ ] submergence (complete) rice (ssp. indica, aus and japonica) near isogenic lines; sub a- transgenics growth restriction; quiescence strategy sub a- , ethylene, reduced ga responsiveness [ , , ] submergence (seed) rice (ssp. indica) anaerobic germination of tolerant to non-tolerant cultivars; cipk mutant enhanced coleoptile and shoot elongation quantitative trait loci; enhanced starch degradation; cipk [ , ] submergence (under anoxia) rice (ssp. indica) to wheat seed germination and coleoptile elongation adjustment of metabolism; reduced oxygen consumption [ ] wheat (triticum aestivum) to rice no germination and coleoptile elongation inhibited limited adjustment of metabolism and oxygen consumption [ ] submergence marsh dock (rumex palustris) ecotypes with fast and slow underwater elongation responses petiole elongation fast elongation associated with lower endogenous aba [ ] common sorrel (rumex acetosa) to rumex palustris limited petiole elongation maintenance of aba under submergence [ ] arabidopsis thaliana accessions varied survivability unknown [ ] meionectes brownii variation in light photosynthetic aquatic adventitious roots reduced need for shoot photosynthate [ ] anoxia rice to wheat sucrose or glucose-fed wheat seeds survive longer a-amylase produced under anoxia in rice but not in wheat seedlings [ ] chlamydomonas reinhardtii wild type to mutant transcriptomic and metabolic adjustments versatile metabolic adjustments such as h production [ – ] pondweed (potamogeton distinctus) to pea (pisum sativum) turion elongation and survival enhanced h + extrusion and stabilization of cytosolic ph [ ] grape (vitis sp.) anoxia tolerant (vitis riparia) to intolerant (vitis rupestris) improved survival of hypoxia pretreated roots fermentation and maintenance of ion homeostasis (e.g. k + ) [ ] hypoxia to anoxia arabidopsis thaliana wild type to loss-of-function or other insertion mutants and overexpression transgenics low oxygen and/or submergence survival hre , hre , rap . , rap . ; vernalization insensitive ; exordium ; heat shock factor a; hypoxia-responsive unknown protein (hup) genes [ , , , , , , , , , ] wild type to loss-of-function prt and ate ate mutants low oxygen and/or submergence survival; seed germination under hypoxia n-end rule pathway components prt , ate , ate [ , ] wild type to loss-of-function mutants and overexpression transgenics seed germination under . % oxygen nac transcription factor anac [ ] waterlogging lotus japonicus wild type to n-deficient nodular leghemoglobin rnai transgenics alanine and succinate accumulation modified tca flux mode [ ] poplar (populus � canescens) root to shoot transcriptomic and metabolic adjustments; limited shoot response unknown [ ] cotton (gossypium hirsutum) root to shoot transcriptomic and metabolic adjustments; shoot growth inhibition unknown [ ] maize (zea mays) root cell type mrnas aerenchyma formation ethylene, ca + , ros; cortex mrnas [ ] rice response to compounds adventitious root development epidermal cell death mediated by ethylene and ros [ ] tomato (solanum lycopersicum) response to hormone biosynthesis inhibitors adventitious root development ethylene and auxin [ ] review trends in plant science march , vol. , no. udp sus amylasesinv h o glucose glucose glucose- -p glucose- p glucose- -pudp-glucose fructose fructose- p fructose- , p phosphoenolpyruvate pyruvate acetaldehyde glutamate aspartate -oxoglutarate -oxoglutarate oxaloacetate isocitrate malate fumarate glutamate -oxoglutarate citrate succinyl coa succinic semialdehyde oxidative phosphorylation +o α-ketoacid fructose ++ ppi ppi pi pi sucrose starch utp utp utp atp atp atp atp nadh nadh nadh nadh nad(h) fadh nadh non-circular tca flux nadh amino acid ldh pdc gdh nadp(h) mdh gad adh nad+ nad+ nad+ nad+ nad+ nad(p)+ nad(p)+ nadp(h) atp atp adp scs atp atp nh + nad+ nad+ nad+ h+ nad+ atp + pi amp + ppi atporor atp adp adp adp adp nadh glycolysis glycolysis upregulated by low oxygen (pasteur effect) to increase substrate level atp production fermentation induced by low oxygen; aids redox equilibration and provides nad+ to maintain glycolysis gaba shunt gad uses protons as substrate and may help stabilize cytosolic ph decreased respiration may occur by downregulation of net nadh production via the tca cycle or reduced metc activity; conserves oxygen starch breakdown amylase levels increase in some species to keep pace with increased carbon demand alanine and og shunt prevents loss of carbon via fermentation and routes og into the oxidative tca branch to yield additional atp by substrate level phosphorylation energy efficiency sucrose degradation shifts from inv to sus; some species use ppi consuming enzymes in sucrose breakdown and glycolysis, increasing net production of atp lactate alanine succinate gaba ethanol adp adp udp udp trends in plant science acetyl coa figure . metabolic reconfiguration under low oxygen stress. reduced oxygen availability alters metabolism to maximize substrate level atp production. the model depicts the major known changes that include enhanced sucrose–starch metabolism, glycolysis, fermentation, a modified tricarboxylic acid (tca) flow, an alanine and - oxoglutarate ( og) shunt and a g-aminobutyric acid (gaba) shunt. the hypothesis that oxygen is conserved is under further investigation. yellow boxes summarize notable metabolic adjustments. blue lines indicate pathways enhanced during the stress, blue dashed lines indicate pathways proposed to be active during the stress and gray dashed lines indicate reactions that are inhibited during the stress. metabolites that increase during the stress are shown in enlarged black font; metabolites that decrease are shown in red font. abbreviations are as follows: og, -oxoglutarate; adh, alcohol dehydrogenase; gad, glutamic acid decarboxylase; gdh, glutamate dehydrogenase, inv, invertase; ldh, lactate dehydrogenase; mdh, malate dehydrogenase; pdc, pyruvate decarboxylase; scs, succinyl coa ligase; sus, sucrose synthase. review trends in plant science march , vol. , no. review trends in plant science march , vol. , no. acid (aba) and gibberellins (ga), which normally limits cell elongation. in rice, natural variation in the presence and absence of the underwater escape [snorkel (sk) and ] and submergence tolerance (sub a) group vii erf determinants underlies differential regulation of the hor- monal cascade and hormone sensitivities that control un- derwater growth [ ] (box ). two r. palustris populations distinguished by fast and slow underwater petiole elonga- tion were differentiated by the maintenance of higher levels of aba and reduced ga responsiveness in the slow elongating variety during submergence [ ]. consistently, the limited underwater petiole growth and prolonged sub- mergence survival of r. acetosa was linked to maintenance of aba biosynthesis that translated into lower ga respon- siveness during submergence [ ]. photosynthesis can continue in submerged leaves and is aided by the gas film that often clings to their surface [ , ]. it follows that the degree of oxygen deprivation in photosynthetic tissue may be less extreme than tissues distant from an oxygen source. nevertheless, the ethylene- driven underwater elongation of shoot tissue can deplete carbohydrates and lead to an energy crisis. box . contrasting submergence survival strategies of rice most accessions respond to submergence through rapid shoot elongation, which allows emergence from a shallow flood [ ]. a limited number of accessions display the ability to survive a slow progressive flood (escape response) or a deep transient flash flood (quiescence response) (figure i). (a) by amplifying the elongation of stem internodes, deepwater rice can outgrow a progressive flood and survive partial inundation for months. this deepwater escape strategy is controlled by the snorkel (sk) locus, which encodes two group vii erfs, sk and sk [ ]. sks are absent from lowland varieties. (b) the molecular genetic analysis of the submergence-tolerant acces- sion fr a revealed that the submergence (sub ) locus, encoding two or three group vii erfs, regulates the quiescence response. sub b and sub c are invariably encoded at sub in lowland accessions, whereas sub a is limited to some indica and aus landraces [ , ]. the sub a- allele is sufficient to confer survival of weeks or longer of complete submergence. (c) model of the core submergence response network that is influenced by sks and sub a. genotypes possess either sk /sk , sub a or neither. both sk /sk and sub a- mrna are ethylene induced. in deepwater rice, sk / sk and two minor qtls augment accumulation of bioactive ga in stem internodes during submergence. in submergence tolerant rice varieties, the presence of sub a- influences submergence and post- submergence responses in aerial tissue. ( ) sub a- mrna is ethylene-induced but ultimately limits ethylene biosynthesis [ ]. ( ) sub a- promotes accumulation of two negative regulators of ga responses [slender rice (slr ) and slender rice-like (slrl )] [ ]. ( ) sub a- does not perturb the submergence- induced decline in aba content but heightens sensitivity to aba [ ]. ( ) sub a- limits induction of genes associated with starch breakdown [ , , ]. ( ) sub a- enhances upregulation of genes associated with reactive oxygen species (ros) amelioration and survival of dehydration, thereby improving re-establishment follow- ing de-submergence [ ]. ( ) sub a- interacts with a complex network of proteins [ ]. ( ) sub a- transiently restricts the progression to flowering during submergence [ ]. in summary, sub a is remarkably positioned to suspend growth and maintain cell viability during submergence and restore homeostasis during a subsequent recovery period. similarities in transcriptome response to flooding and oxygen deprivation numerous investigations have assessed changes in tran- scriptomes in response to low oxygen stress or flooding in plants including arabidopsis, rice, poplar (populus � canescens) and cotton (gossypium hirsutum) [ , ]. stud- ies performed on seedlings of the arabidopsis col- eco- type include evaluation of the effects of different severity [ ] and duration [ , ] of oxygen depletion, as well as the impact of heat stress prior to anoxia [ ]. because the majority of cellular mrnas are poorly translated during oxygen deprivation [ ], changes in polyribosome-associ- ated mrnas were used to evaluate dynamics in the stress and recovery responses [ ]. in cell types or regions of roots and shoots, polyribosomes were captured by immu- nopurification to identify transcripts regulated by short- term oxygen deprivation [ ]. this approach identified core hypoxia-responsive genes that were strongly induced by the stress across all samples evaluated. also distin- guished were cohorts of mrnas that were hypoxia-re- sponsive at the organ or cell-specific level, although their modulation was less pronounced than the core progressive flood – deepwater rice (sk / ) partial submergence complete submergence submergence reoxygenation ros ros amelioration slr slrl dehydration response drought recovery ethylene aba abasub ask /sk ga elongation growth dehydration reoxygenation and dehydration flash flood – sub rice (sub a) (c) (a) (b) trends in plant science figure i. group vii erfs and pathways that regulate growth responses under distinct flooding regimes. review trends in plant science march , vol. , no. hypoxia-responsive genes. of the core hypoxia-respon- sive genes, were also differentially regulated in roots and rosette leaves during submergence in complete dark- ness [ ]. finally, meta-analyses that compared tran- scriptomic adjustments to low oxygen or flooding stress identified conservation in the core network of genes asso- ciated with signaling, transcription and efficient anaero- bic atp production that is modulated by oxygen deprivation in a range of plants [ , ]. how do plant cells sense low oxygen stress? based on mechanisms in other eukaryotes, both indirect and direct sensing of cellular oxygen status could be re- sponsible for acclimation responses that prolong survival of oxygen deprivation in plants [ ]. indirect sensing mechanisms might include perception of altered energy status through changes in levels of adenylates (atp, adp and/or amp), consumable carbohydrates, pyruvate, cyto- solic ph, cytosolic ca + or localized production of reactive oxygen species (ros) and nitric oxide (no). animal and yeast cells sense and adjust energy homeo- stasis through sucrose non-fermenting (snf )/amp- activated protein kinases [ , ]. the plant energy sensors fall within one clade of snf relatives, the snrk s, some of which have been implicated in low oxygen responses. for example, arabidopsis kin and kin are necessary to limit energy consumption during hypoxia [ ]. whereas in rice seeds germinated under oxygen starvation, the deple- tion of sucrose activates the snrk a energy sensor through the activity of a calcineurin b-like interacting binding kinase (cipk ) [ ]. this signal transduction upregulates transcription of genes encoding a-amylases, which drive catabolism of starch in the seed needed to fuel underwater shoot growth. logically, a reduction of energy consumption is beneficial when atp levels decline. a means of energy conservation during low oxygen stress in plants is selective translation and sequestration of mrnas during hypoxia [ ]. based on evidence from other eukaryotes, the sequestration of a subset of cellular mrnas, such as the abundant cohort that encodes ribo- somal proteins and translation factors, could be regulated through snrk s and the target of rapamycin kinase [ ]. mitochondria are also thought to contribute to oxygen sensing and signaling in plants, through production of no and/or release of ros and ca + during the transition from normoxia to hypoxia [ , ], as confirmed in animals [ , ]. in animals, direct oxygen sensing regulates the accu- mulation of the a subunit of the hypoxia inducible factor (hif) a/b transcription factor [ ]. hif a is constitu- tively synthesized but fails to accumulate under nor- moxia because of oxygen-dependent hydroxylation of specific proline residues that trigger its ubiquitination and s proteasome-mediated degradation. as oxygen declines, the prolyl hydroxylases that modify hif a are less active. consequentially, hif a accumulates and is trafficked to the nucleus where hif a/b can function in transcriptional activation. there is no corol- lary direct oxygen sensing mechanism in plants, because although they possess prolyl hydroxylases they lack hif a [ ]. group vii erfs regulate low-oxygen acclimation responses the plant-specific erf transcription factor family includes over members in rice and arabidopsis, all of which share an apetala (ap ) dna binding domain [ ]. the erfs have been phylogenetically parsed into ten clades, with the group vii erfs characterized by a conserved n terminal motif (nh -mcggai/l) [ ] (figure a). fifteen rice (japonica cv. nipponbare) erfs were designated group viia (oserf - ) and viib (oserf ), based on the presence or absence of the conserved n terminal motif, respectively. the single group viib erf corresponds to sub c, which is found in all rice varieties surveyed [ ] and acts downstream of sub a [ ]. intriguingly, the group vii erfs encoded by sub a, sk and sk possess variant n termini relative to the rice group viia erfs. arabidopsis encodes five group vii erfs (aterf – ), two of which are hypoxia-responsive genes {hypoxia responsive erf and [hre (aterf ; at g ) and hre (aterf ; at g )]}. as ob- served for sub a and the sks, hre mrna accumula- tion is promoted by ethylene, which synergistically enhances its elevation during hypoxia [ , ] (figure b). several recent reports indicate that arabidopsis group vii erfs redundantly regulate hypoxia-responsive gene expression and survival of low oxygen stress. for example, seedling survival of anoxia was more severely compro- mised in hre hre double mutant seedlings than in either single mutant or the wild type [ , ]. by contrast, low oxygen sensitivity was lessened in seedlings that constitu- tively overexpress either hre or hre mrna. the ectopic expression of these erfs was sufficient to heighten induction of the core hypoxia-responsive gene adh or adh enzyme activity during the stress [ , ]. however, because hre hre seedlings were able to elevate adh enzyme activity and ethanol production during hypoxia [ ], genetic redundancy is likely to extend to the other group vii erfs [rap . (aterf ; at g ), rap . (aterf ; at g ) and rap . (atebp/aterf ; at g )]. indeed, conditional upregulation of rap . was sufficient to elevate expression of a padh :- luciferase transgene [ ] and rap . overexpression improved survival of hypoxia in seedlings [ ], whereas the inhibition of either rap . or rap . expression via mirna production limited the induction of adh and several other hypoxia-responsive genes [ ]. the impact of ectopic expression of these genes was condition specific, as hre , hre , rap . and rap . overexpression significantly increased levels of adh mrna or adh activity under low oxygen stress but not under normoxia [ , , ]. nonetheless, rap . , rap . and rap . mrnas accumulate under normoxia in association with polyribosomes [ , ], suggesting they are constitutively synthesized. together, these findings hint that post-trans- lational regulation limits the function of group vii erfs to periods of low oxygen stress. arabidopsis group vii erfs are degraded via the n-end rule pathway the conserved n-end rule pathway of targeted proteolysis regulates the half-life of certain cellular proteins based on pm nucleus a c b p hypoxia responsive rap . rap . rap . rap . rap . normoxia hypoxia flooding normoxia erf erf erf hypoxia flooding -o hre ethylene low o low o constitutiv e dark ethylene constitutive constitutive ethylene ? transcription / translation arabidopsis group vii erfs rap . rap . rap . hre constitutiveee ethylene ??? rap . +o mc erf c erf c* erf hypoxia responsive erf prt , other e s? s proteasome o , no maps ates r-c* ub erf erf erf anaerobic metabolism and other responses erf r-c* r ic e group vii erfs a ra b id o p si s (a) (b) (c) trends in plant science figure . oxygen sensing via n-end rule pathway-targeted turnover of group vii erfs. (a) n terminal alignment of arabidopsis group vii erfs. with the exception of sub c, all begin with the amino acids ‘met-cys’ (mc). the highly conserved arabidopsis n terminal motif is boxed in red and is less conserved in the proteins at loci associated with submergence responses in rice. (b) homeostatic response to hypoxia is regulated by the n-end rule-mediated proteolysis of group vii erfs in arabidopsis. group vii erf transcription factors are either constitutively expressed and/or differentially transcriptionally regulated in response to variable signals, including low o , ethylene and darkness. four of the five erfs (hre , hre , rap . and rap . ) have been implicated in the regulation of hypoxia-responsive genes. under oxygen-replete conditions (normoxia), erfs are degraded via the n- end rule pathway of proteolysis. this involves the following steps: (i) the n terminal met (m) is constitutively cleaved by a methionine aminopeptidase (map); (ii) the exposed cys (c) is converted to an oxidized (c*) form (e.g. cys-sulfonic acid) by o , no or possibly ros; (iii) an arg (r) residue is added to the oxidized review trends in plant science march , vol. , no. recognition of n terminal residues by specific n-recognin e ligases [ ]. in plants, amino acids function as destabilizing residues when located at the n terminus of a protein, which coupled with an optimally positioned downstream lysine can act as a degradation signal (n- degron) [ ]. in plants and animals but not yeast, a cyste- ine (cys) residue at the n terminus can undergo two steps of modification that lead to protein recognition and degra- dation (figure b). based on mechanistic studies in mam- mals, newly synthesized proteins with a cys as the second residue (i.e. nh –met –cys ) are constitutively cleaved by a met amino peptidase (map) to yield nh –cys . in ara- bidopsis, a small family of functionally redundant maps catalyzes this reaction [ ]. the exposed cys can be spontaneously or enzymatically oxidized in an o - or no-dependent manner to cys-sulfinate or further to cys-sulfonate [ ]. as a result of oxidation, an arginine residue is added to the nh –cys by an arginyl trna transferase (ate), targeting the protein for recognition by an n-recognin e ligase, leading to ubiquitination and s proteasome-mediated degradation. in arabidopsis, the genes ate and ate encode the arg transferases [ ] and at least one e ligase, encoded by proteolysis (prt ), acts as an n-recognin of nh –arg –cys oxidised polypeptides [ ]. the distinct conservation of the n terminus of group vii erfs and the serendipitous observation that an arabidop- sis prt mutant constitutively accumulates adh and other hypoxia-responsive mrnas in seeds led to the con- firmation that group vii erfs are bona fide substrates of the n-end rule pathway in plants [ , ] (figure b). additional support of this conclusion was obtained through in vitro and in planta analyses. an in vitro system derived from rabbit reticulocytes [ ] was used to confirm that all five arabidopsis group vii erfs are n-end rule substrates. it was also shown that their instability required cys , as mutation of cys to the stabilizing residue ala (nh –met –ala ) eliminated sus- ceptibility to n-end rule turnover. it was further demon- strated in planta that low oxygen stress increased the accumulation of group vii erfs synthesized with a native n-terminus (nh –met –cys ), whereas those synthesized with an nh –met –ala n terminus were stable under both normoxia and hypoxia [ , ]. based on this evidence, the stabilization of group vii erfs under hypoxia is most probably related to an inhibition of the cys oxidation that is required before the protein can be arginylated and degraded. cys by an arginyl trna transferase (ate); and (iv) the argininylated protein is recognized by proteolysis (prt ) or other e ligases, which polyubiquitinate the protein, targeting it for proteasomal degradation ( s proteasome). the outcome is prevention of transcription of hypoxia-responsive genes under normoxia. when oxygen becomes limiting (hypoxia), degradation of the erfs by the n-end rule pathway is inhibited due to a lack of oxygen-mediated cys oxidation. stabilized erfs can then drive the transcription of genes that enhance anaerobic metabolism and other survival responses. upon return to aerobic conditions, the erfs are once again destabilized, providing a feedback mechanism that allows the plant to return to aerobic metabolism. (c) atrap . localization dynamics. at least one group vii erf, rap . , associates with the plasma membrane (pm) via interaction with acbp, limiting its turnover under normoxia. during hypoxia rap . is relocated to the nucleus and activates gene expression. upon reoxygenation, rap . is destabilized, presumably as a consequence of cys oxidation and n-end rule-mediated degradation. box . key questions for future experimentation � can o , no or ros-dependent cys oxidation, arginylation and ubiquitination of group vii erfs be experimentally confirmed? if so, is the oxidation spontaneous or catalyzed? � what are the kinetics of oxygen-regulated group vii erf turnover? does erf stabilization occur before oxygen deficiency impairs cytochrome c oxidase activity? � does the oxygen level affect the interaction between acbps and rap . ? does docking of rap . to acbp impair cys oxida- tion, modification by ate, or interaction with an e ligase? are other group vii erfs similarly sequestered? � what genes and networks are controlled by individual group vii erfs? � is the activity or turnover of sub a, which apparently escapes oxygen-mediated n-end rule degradation, controlled upon de- submergence? � can manipulation of group vii erf accumulation and turnover provide an effective strategy to modulate survival of flooding in crops? review trends in plant science march , vol. , no. either the modification of the n terminus of a group vii erf or disruption of an n-end rule pathway step can affect survival of low oxygen stress or submergence in arabi- dopsis [ ]. for example, stabilization of hre and hre by modification of the n terminus to nh –met –ala was sufficient to improve seed germination and seedling sur- vival under hypoxia [ ]. in addition, ate ate and prt seedlings were less sensitive to hypoxia when grown on sucrose-supplemented medium [ ]. the same mutants grown to the rosette stage were more sensitive to submer- gence in complete darkness [ ]. this discrepancy in phenotype might be explained by distinctions in the avail- able carbohydrates in the two survival assays. in the low oxygen experiments, anaerobic metabolism was fueled by sucrose in the medium, whereas in the submergence experiments it was limited to endogenous energy reserves of the plant. therefore, the absence of prt or ate activity may enhance anaerobic metabolism to prolong survival in sucrose-fed seedlings but may cause a more rapid onset of energy deficiency in submerged plants. these findings are reminiscent of the earlier proposal that a balance between energy consumption and conservation is crucial to survival of low oxygen stress and submergence [ , ]. it was also observed that the onset of the transcription of hypoxia-responsive genes occurs concomitantly with relocalization of rap . to the nucleus under hypoxia (figure c) [ ]. during normoxia, a gfp-tagged version of rap . was protected against protein degradation by the n-end rule pathway of proteolysis and excluded from the nucleus via interaction with a plasma membrane (pm)- associated acyl-coa binding protein (acbp or acbp ). rap . migrated to the nucleus in response to hypoxia and disappeared from the nucleus after reoxygenation. moreover, transient expression of rap . -gfp in leaves of ate ate and prt mutants resulted in greater gfp signal intensity in the nucleus under normoxia and follow- ing reoxygenation. in summary, the n-end rule pathway of proteolysis regulates the accumulation of group vii erfs and conse- quentially the accumulation of gene transcripts associated with low oxygen responses in arabidopsis. it is proposed that constitutively synthesized group vii erfs are either degraded or sequestered under normoxia, as confirmed for rap . . as oxygen levels fall their degradation becomes limited, pm sequestration is reversed and the erf is transported to the nucleus and becomes active in gene regulation. upon reoxygenation, both constitutively expressed and hypoxia-induced group vii erfs are desta- bilized. thus, the n-end rule pathway (i) prevents the excessive accumulation of constitutively expressed erfs under normoxia; (ii) allows for stabilization of both consti- tutive and induced erfs during hypoxia; and (iii) facil- itates rapid reversal of erf-regulated transcription upon reoxygenation. constitutively expressed group vii erfs are proposed to encode oxygen sensors that conditionally activate transcription of hypoxia-responsive genes, includ- ing other group vii erfs [ ]. the increased synthesis of n-end rule regulated group vii erfs by ethylene or darkness could further prime cells for acclimation to oxy- gen deprivation. manipulation of n-end rule regulation of group vii erfs and other proteins the verification that the n-end rule pathway modulates group vii erf accumulation in the nucleus in an oxygen- dependent manner exposes the first examples of n-end rule substrates and a homeostatic low oxygen sensor mech- anism in plants. based on available gene sequence data, group vii erfs with the conserved n-terminus are broad- ly found in vascular plant species [ ]. we propose that future improvement of flooding tolerance could be achieved by manipulation of synthesis and turnover of these pro- teins (e.g. by overexpression, regulated expression and/or mutation of nh –met –cys to nh –met –ala ). given the crucial importance of modulation of energy reserves during flooding, it is not surprising that variation of group vii erf susceptibility to oxygen-dependent n- end rule turnover exists in nature. the rice nipponbare genome encodes group vii erfs with the conserved n terminus that is consistent with oxygen-regulated n-end rule-targeted proteolysis in arabidopsis. however, neither sub a nor sub c are n-end rule substrates based on in vitro data [ ] and the n termini of sk and sk also deviate from the consensus associated with n-end rule- mediated turnover. this leads us to propose that the escape of sub a from n-end rule pathway turnover could allow the ethylene-mediated regulation of sub a- to trigger the sequence of events that promotes the energy management associated with submergence tolerance well before oxygen levels reach a critical nadir. concluding remarks: direct oxygen sensing via the n- end rule regulates transcription alterations in gene expression associated with increased catabolism and substrate level atp production are a hallmark of reduced oxygen availability and flooding in plants. group vii erfs play a prominent role in this process. the identification of an oxygen-dependent pro- tein turnover mechanism that controls the abundance of some but not all group vii erfs raises several pertinent questions (box ). we anticipate that genetic manipula- tion of the targets of oxygen-regulated n-end rule pathway turnover can provide a means to improve survival under a variety of flooding conditions. review trends in plant science march , vol. , no. acknowledgments submergence and hypoxia research in the bailey-serres group is supported by the national science foundation (ios- ; ios- ) and the united states department of agriculture ( - - ), in the van dongen group by the german research foundation (dfg; do / - ) and the federal ministry of education and research (bmbf; hydromicpro), in the perata group by scuola superiore sant’anna (a pp-a pp), and in the voesenek group by grants from the netherlands organization for scientific research and center for biosystems and genomics (cbsg ). n-end rule pathway research in the holdsworth group is supported by the biotechnology and biological sciences research council (bb/g / ). references tester, m. and langridge, p. 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( ) expression of rice sub a and sub c transcription factors in arabidopsis uncovers flowering inhibition as a submergence tolerance mechanism. plant j. , – 	making sense of low oxygen sensing 	improved crop survival of floods is needed 	oxygen deprivation is a frequent component of flooding stress 	ethylene initiates submergence survival strategies in rice and wetland species 	similarities in transcriptome response to flooding and oxygen deprivation 	how do plant cells sense low oxygen stress? 	group vii erfs regulate low-oxygen acclimation responses 	arabidopsis group vii erfs are degraded via the n-end rule pathway 	manipulation of n-end rule regulation of group vii erfs and other proteins 	concluding remarks: direct oxygen sensing via the n-end rule regulates transcription 	acknowledgments 	references u n i v e r s i t y o f c o p e n h a g e n bioenergy crisis in coronavirus diseases? dutta, anirban; das, abhijit; kondziella, daniel; stachowiak, michal k. published in: brain sciences doi: . /brainsci publication date: document version publisher's pdf, also known as version of record document license: cc by citation for published version (apa): dutta, a., das, a., kondziella, d., & stachowiak, m. k. ( ). bioenergy crisis in coronavirus diseases? brain sciences, ( ), [ ]. https://doi.org/ . /brainsci download date: . apr. https://doi.org/ . /brainsci https://doi.org/ . /brainsci brain sciences editorial bioenergy crisis in coronavirus diseases? anirban dutta ,* , abhijit das , daniel kondziella , and michal k. stachowiak department of biomedical engineering, university at buffalo, buffalo, ny , usa department of neurology, the walton centre nhs foundation trust, liverpool l lj, uk; abhijit.neuro@gmail.com department of neurology, rigshospitalet, copenhagen university hospital, copenhagen, denmark; daniel.kondziella@regionh.dk department of clinical medicine, faculty of health and medical sciences, university of copenhagen, copenhagen, denmark department of pathology and anatomical sciences, university at buffalo, buffalo, ny , usa; mks @buffalo.edu * correspondence: anirband@buffalo.edu; tel.: + - - - received: march ; accepted: april ; published: may ���������� ������� coronavirus disease (covid- ) has been declared as a pandemic by the world health organization (who). typical symptoms reported in covid- are respiratory illness. about % of the infections are not severe (even asymptomatic), whereas out of the hospitalized covid- patients with pneumonia, about % developed hypoxemia by day eight while about – % developed acute respiratory distress syndrome (wuhan experience) [ ]. recently, neurological complications are increasingly reported [ ], including encephalopathy in an elderly -year-old male [ ]. the computed tomography (ct) scan of the head showed no acute abnormalities; however, the electroencephalogram (eeg) showed bilateral slowing and focal slowing in the left temporal region with sharply countered waves. this led to the possibility of subclinical seizures due to the presence of an area of encephalomalacia consistent with the prior history of embolic stroke, and the patient remained in the intensive care unit (icu) with poor prognosis. filatov et al. [ ] found that elderly patients with such chronic conditions and with acute infections are at an increased risk of altered mental status even though covid- did not cause meningitis or encephalitis in this case study. nevertheless, filatov et al. [ ] case study highlighted the need to identify encephalopathy as a presenting sign of covid- , especially in cases with altered mental status including delirium, where severe cases can lead to long-term cognitive impairments. respiratory virus infections trigger inflammatory responses both at the site of infection (in the upper and lower respiratory tract) as well as systemically. here, sepsis-associated encephalopathy (sae) can be a transient and reversible brain dysfunction in patients with covid- , where a subgroup of critically ill patients can develop septic shock [ ]. anti-tumor necrosis factor (tnf) antibodies have been found in the blood and diseased tissues of covid- patients [ ]. the severity of inflammatory excess is due to the cascade of cytokine production, the cytokine storm, where tnf can act as an amplifier of inflammation [ ]. intracranial cytokine storms can result in blood-brain-barrier breakdown without direct viral invasion [ ]. in fact, the endothelium is a principal organ involved in the pathogenesis of sepsis, leading to multiple organ failure [ ]. the clinical spectrum of sae can include sickness behavior, delirium, focal deficits, and coma [ ]. the eeg features of sae can include excessive theta rhythms, predominant delta rhythms, triphasic waves, and burst suppression along with seizures in up to % of patients. the review by heming et al. [ ] highlighted the use of various eeg monitoring tools in sepsis; however, heming et al. [ ] also found that the eeg monitoring methods remained ill-defined for sepsis. heming et al. [ ] reported that sae is associated with neurovascular uncoupling due to microcirculatory dysfunction and low blood flow. therefore, we postulate that the use of brain sci. , , ; doi: . /brainsci www.mdpi.com/journal/brainsci http://www.mdpi.com/journal/brainsci http://www.mdpi.com https://orcid.org/ - - - http://dx.doi.org/ . /brainsci http://www.mdpi.com/journal/brainsci https://www.mdpi.com/ - / / / ?type=check_update&version= brain sci. , , of eeg monitoring will be more informative in conjunction with functional near-infrared spectroscopy (nirs) such that any neurovascular uncoupling can be detected [ ] during eeg events. neurovascular coupling is important since it adapts local cerebral blood flow to the neural metabolic needs [ ] that maintains the neuroenergetic status of the neurovascular tissue so any neurovascular uncoupling can lead to an energy crisis in the brain tissue [ ]. here, a majority of the energy in the brain is generated by the oxidative phosphorylation in the mitochondria where the energy currency, adenosine triphosphate (atp), production rate plays a central role in brain bioenergetics [ ]. lee and huettemann [ ] presented a model in which inflammatory signaling changes the phosphorylation state of the mitochondrial proteins leading to inhibition of the oxidative phosphorylation. since oxidative phosphorylation in the mitochondria generates a majority of the atp so inhibition of the oxidative phosphorylation can lead to an energy currency crisis. moreover, hypoxemia due to severe respiratory failure in respiratory virus infections can further aggravate the energy crisis. powerful anti-inflammatory drugs can limit the inflammation but have the risk of increasing viral replication or bacterial infections [ ], which can lead to meningitis/encephalitis [ ]. therefore, investigation of an adjunct therapy targeting dysfunctional mitochondrial metabolism [ ] is proposed, including photobiomodulation [ ], since atp acts as a purinergic feedback signaling molecule where low atp concentrations almost exclusively recruit microglial cells [ ]. purinergic signaling cascade is also involved with the complex vascular response at the capillaries (pericytes) [ ], which can be partly responsible for the cerebrovascular complications of covid- [ ]. we further postulate that continuous fnirs–eeg joint monitoring can be a useful bedside multimodal monitoring tool in neuro icu [ ] to detect transient neurovascular uncoupling. continuous fnirs–eeg joint monitoring will also be essential to monitor the effect of some sedative drugs that can affect neurovascular coupling and may increase the risk of delirium. however, patients in neuro icu rarely undergo continuous brain monitoring along the lines of continuous electrocardiogram (ecg) in the cardiac icu. here, portable platforms with centralized multimodal data acquisition and signal processing have been found useful [ ]. moreover, some patients can be particularly susceptible to cytokine storms [ ], where continuous brain monitoring can be necessary for triaging. also, identifying genetic mechanisms underlying brain susceptibility to cytokine storms [ ] will be important as predictors in addition to quantitative brain monitoring measures. specifically, genetic insights into the mechanisms of fibroblast growth factor (fgf) signaling [ ]. fgf signaling is increasingly being found essential for metabolic homeostasis in the tissues [ ], where aberrant fgf receptor can enhance the warburg effect and mitochondrial dysfunction [ ]. recent data shows that fgf protects against hypoxia stress-induced injury in the cerebral microvascular endothelial cells [ ]. so, fgf signaling can have a protective role not only in hypoxia-related brain disorders, e.g., encephalopathy, but also in neurodevelopmental disorders, e.g., schizophrenia [ ], due to prenatal immune insult [ ]. without quantitative brain monitoring of the neuroenergetics and the functional genomics, deeper understanding of the early neurovascular signs of sae will remain unfulfilled that is important for triaging and for tailoring the therapies. mitochondrial dysfunction related to microcirculatory dysfunction [ ], with an inhibition of mitochondrial respiratory chain and a decrease of oxygen utilization, remains poorly understood [ ]. an increased level of proinflammatory cytokines (such as tnf, interleukins, etc.) can affect various organs by affecting their mitochondrial energy homeostasis and vascular hyperpermeability where the initial effects can be found in the skeletal muscles, heart, liver, and lungs. here, mitochondrial respiration, which seems to evolve during sepsis [ , ], can be monitored using non-invasive broadband near-infrared spectroscopy of the cytochrome oxidase redox state [ ] in various tissues including skeletal muscles. yamane et al. [ ] showed in severe influenza the relation between the host metabolic disorder-cytokine cycle and the influenza virus-cytokine-trypsin cycle in the skeletal muscles, heart, liver, and lungs (but not in the brain) which were driven by the cytokine storm. immunomodulatory therapy has been proposed to improve the outcome in severe influenza [ ]; however, its effects in the case of coronavirus disease are currently being evaluated (https://www.biocentury.com/article/ ) [ ]. https://www.biocentury.com/article/ brain sci. , , of nevertheless, human as well as animal studies are expensive and time-consuming so we propose a phase- paradigm for drug screening and personalized medicine using microglia-containing organoid models [ , ]. this is crucial since immunomodulation can be a double-edged sword where some patients can be more susceptible than others [ ]. we also propose a mini-brain computer interface (see figure ) [ ] that combines electrophysiological recordings (using open ephys [ ]) and vis-near-infrared (nir) broadband spectroscopy [ ] to monitor the neuronal as well as neurometabolic coupling state in the microglia-containing cerebral-vascular organoids. figure shows the experimental setup where a -channel d microelectrode array (mea) based electrophysiological (ephys) recording was combined with the broadband vis-nir spectroscopy of the activity of the mitochondrial electron transport chain (etc) complexes. also, computational anatomy and functional genomics were performed on the organoids [ ] that are proposed to investigate genetic mechanisms underlying brain susceptibility to cytokine storms [ ] and bioenergy crisis. brain sci. , , of others [ ]. we also propose a mini-brain computer interface (see figure ) [ ] that combines electrophysiological recordings (using open ephys [ ]) and vis-near-infrared (nir) broadband spectroscopy [ ] to monitor the neuronal as well as neurometabolic coupling state in the microglia- containing cerebral-vascular organoids. figure shows the experimental setup where a -channel d microelectrode array (mea) based electrophysiological (ephys) recording was combined with the broadband vis-nir spectroscopy of the activity of the mitochondrial electron transport chain (etc) complexes. also, computational anatomy and functional genomics were performed on the organoids [ ] that are proposed to investigate genetic mechanisms underlying brain susceptibility to cytokine storms [ ] and bioenergy crisis. in the subsequent human drug studies, broadband near-infrared spectroscopy of the brain [ ] and the skeletal muscles can monitor the evolution of the systemic inflammatory response [ ] to tailor the immunomodulation. an inexpensive solution using multi-wavelength continuous-wave (cw) nirs–eeg multimodal monitoring has been developed for bedside continuous monitoring in the acute brain injury [ ] to measure the neurovascular coupling (neuroenergetics) in the brain. multiple wavelengths can be selected in the near-infrared optical windows [ ] for robust cw-nirs of the skeletal muscles and the brain where eeg in the case of the brain can provide additional metabolic disorder related features in the patients [ ]. here, the coupling relation of those eeg events, including non-convulsive status epilepticus, vis-à-vis multi-wavelength cw-nirs-measured changes in the oxy- and deoxyhemoglobin as well cytochrome oxidase redox state can provide a marker of the severity of sae. therefore, we postulate that the normalization of dysfunctional eeg features as well as the neuroenergetics (from neurovascular and neurometabolic coupling) may be a prognostic marker of intact recovery without long-term cognitive impairments in the critically ill covid- patients with transient and reversible brain dysfunction due to sae. furthermore, we highlight the need to investigate continuous bedside monitoring of bioenergetics, including mitochondrial etc complexes, in the skeletal muscles and the brain in sepsis. figure . mini-brain computer interface that combines electrophysiological recordings with the vis- near-infrared (nir) broadband spectroscopy to monitor the neuronal, metabolic, as well as neurometabolic coupling state in the cerebral vascular organoids (adapted from [ ]). figure . mini-brain computer interface that combines electrophysiological recordings with the vis-near-infrared (nir) broadband spectroscopy to monitor the neuronal, metabolic, as well as neurometabolic coupling state in the cerebral vascular organoids (adapted from [ ]). in the subsequent human drug studies, broadband near-infrared spectroscopy of the brain [ ] and the skeletal muscles can monitor the evolution of the systemic inflammatory response [ ] to tailor the immunomodulation. an inexpensive solution using multi-wavelength continuous-wave (cw) nirs–eeg multimodal monitoring has been developed for bedside continuous monitoring in the acute brain injury [ ] to measure the neurovascular coupling (neuroenergetics) in the brain. multiple wavelengths can be selected in the near-infrared optical windows [ ] for robust cw-nirs of the skeletal muscles and the brain where eeg in the case of the brain can provide additional metabolic disorder related features in the patients [ ]. here, the coupling relation of those eeg events, including non-convulsive status epilepticus, vis-à-vis multi-wavelength cw-nirs-measured changes in the oxy- and deoxyhemoglobin as well cytochrome oxidase redox state can provide a marker of the severity of sae. therefore, we postulate that the normalization of dysfunctional eeg features as well as the neuroenergetics (from neurovascular and neurometabolic coupling) may be a prognostic marker of intact recovery without long-term cognitive impairments in the critically ill covid- patients with transient and reversible brain dysfunction due to sae. furthermore, we highlight the need to investigate continuous bedside monitoring of bioenergetics, including mitochondrial etc complexes, in the skeletal muscles and the brain in sepsis. brain sci. , , of author contributions: writing—original draft, a.d. (anirban dutta); methodology, d.k.; writing—review & editing, a.d. (anirban dutta), a.d. 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solve this captcha to request unblock to the website 	 		you reached this page when trying to access 		https://iopscience.iop.org/journal/ - from 		 . . . on 		april , : : utc 	 microsoft word - -권오유 - - biomedical science letters , ( ): ~ http://dx.doi.org/ . /bsl. . . . eissn : - expression of beta-catenin-interacting protein (ctnnbip ) gene is increased under hypothermia but decreased under additional ischemia conditions kisang kwon , seung-whan kim , kweon yu and o-yu kwon ,† department of biomedical laboratory science, college of health & welfare, kyungwoon university, gumi - , korea department of emergency medicine, chungnam national university hospital, taejon - , korea korea research institute of bioscience & biotechnology, taejon - , korea department of anatomy, college of medicine, chungnam national university, taejon - , korea it has recently been shown that hypothermia treatment improves brain ischemia injury and is being increasingly considered by many clinicians. however, the precise roles of hypothermia for brain ischemia are not yet clear. in the present study we demonstrated firstly that hypothermia induced beta-catenin-interacting protein (ctnnbip ) gene expression and its expression was dramatically decreased under ischemic conditions. it was also demonstrated that hypothermia activated endoplasmic reticulum (er) stress sensors especially both, the phosphorylation of eif α, and atf proteolytic cleavage. however, the factors of apoptosis and autophagy were not associated with hypothermia. these findings suggested that hypothermia controlled ctnnbip gene expression under ischemia, which may provide a clue to the development of treatments and diagnostic methods for brain ischemia. key words: hypothermia, ischemia, ctnnbip , er stress sensor brain ischemia is also known as ischemic stroke, cerebral ischemia and cerebrovascular ischemia. its main cause is insufficient blood flow to the brain. this results in the death of brain tissue by poor oxygen/atp supply, which eventually leads to alterations in brain metabolism, reduction in metabolic rates, and energy crisis (kristián, ; kalogeris et al., ). limited thrombolytics to prevent clots in the blood, caused by operative procedure of carotid endarterectomy may be used in parallel for brain ischemia treatment (yong et al., ). however, thus far obvious cause and treatment effects have not been construed. it is known that hypothermia is one of the effective methods to reduce ischemic brain injury, and may be expected in emergency brain resuscitation of ischemic patients (drury et al., ; zhang et al., ; lemmers et al., ). cellular response of hypothermia results in altered gene expression and decreased oxygen/atp consumption, how- ever the detailed intracellular mechanism is unknown. further study is required to delineate the precise mechanisms of how mild hypothermia prevents neuronal cell death. our previous studies using the differential display (dd)-pcr experiment with gene fishing deg premix kit (seegene co.), have shown that hypothermia increased the expression of beta-catenin-interacting protein (ctnnbip ) gene, a well-known negative regulator of the wnt signaling pathway (tago et al., ). recent studies have illustrated the relationship between the hypothermia and intracellular signaling. here, we tested whether the expression of brief communication *received: july , / revised: july , accepted: august , † corresponding author: o-yu kwon. department of anatomy, college of medicine, chungnam national university, taejon - , korea. tel: + - - - , fax: + - - - e-mail: oykwon@cnu.ac.kr ○c the korean society for biomedical laboratory sciences. all rights reserved. - - ctnnbip was associated with hypothermia, ischemia, endoplasmic reticulum (er) stress, apoptosis and autophagy, especially er stress signaling. pc cells (derived from a pheochromocytoma of the rat adrenal medulla) were cultured on collagen coated flasks in % rpmi supplemented with mm hepes buffer, % heat-inactivated horse serum and % heat-inactivated fetal bovine serum, mm l-glutamine, mm sodium pyruvate, g/l d-(+)-glucose, and antibiotics: μg/ml streptomycin and u/ml penicillin at ℃ in a % co atmosphere. total rna from cultured cells was extracted using an rna isolation reagent (tri-reagent ambion, austin, usa). rt-pcr using the forward primer f ( '- agtggtggccactaatggag- ') and r ( '-tctttt- gtcaggggtcgttc- ') for bip; f ( '-gggagtctt- gtcgtggaattg- ') and r ( '-tgctttccaagacg- gcaga- ') for calnexin; f ( '-caggatttgccctat- ccaga- ') and r ( '-gtcattccgttccttctcca- ') for pdi; f ( '-atgaaccgtgagggagcac- ') and r ( '-gatctggaaaacgccatcagc- ') for ctnnbip ; f ( '-tcagcttcgacaccaatgag- ') and r ( '-gta- tcctcgggaccggttat- ') for cirbp; f ( '-ttacc- tccaccagcaggaac- ') and r ( '-accacctctct- gtgcaatcc- ') for bak ; f ( '-aagctgcacagcgg- ggctaf- ') and r ( '-cagatgccggttcaggtact - ') for bcl ; f ( '-gcctgtcctggataagacca- ') and r ( '-gttcaccagcaggaagaagg- ') for lc ; f ( '-gtgctcctgtggaatggaat- ') and r ( '-gct- gcacacagtccagaaaa- ') for beclin; f ( '-acat- caaatggggtgatgct- ') and r ( '-aggagacaa- cctggtcctca- ') for β-actin were performed for cycles [ ℃ for s; ℃ for s; and ℃ for min (but min in the final cycle)] with taq dna polymerase. western blotting detection system kit (amersham, uppsala, sweden) was used for atf fragmentation and phos- phorylation of eif α. eif α-p antibody and goat anti-actin antibody were purchased from santa cruz biotechnology (santa cruz, ca, usa). mouse anti-atf antibody was obtained from imgenex (san diego, ca, usa). pc cells were incubated under control conditions ( ℃) or hypothermia ( ℃) for or day, respectively. the expression of cold-induced rna-binding protein (cirbp) was used as a positive control (al-fageeh and smales, ). we found that the expression of ctnnbip was increased about . folds by day-hypothermia com- pared to its control; but the exposure to day-hypothermia induced a slight decrease (about fold) in gene expression. the result showed that hypothermia increased ctnnbip mrna expression (fig. ). we surmised from the result shown in fig. , that hypothermia obviously induced the expression of ctnnbip gene. we determined ctnnbip gene expression in both, cells treated with hypothermia fig. . hypothermia increases ctnnbip mrna expression. pc cells were incubated under control conditions ( ℃) or hypothermia ( ℃) for ~ day. hypothermia response was confirmed by increased expression of cirbp mrna which is a positive marker. ctnnbip ; beta-catenin-interacting protein , cirbp; cold-induced rna-binding protein. the experiments were performed thrice and the results represent the average (b) and representative results are shown (a). a b - - fig. . hypothermia decreases ctnnbip mrna expression under the ischemia. pc cells were incubated under control conditions ( ℃), hypothermia ( ℃), ischemia under hypothermia ( ℃) for - day, respectively. ctnnbip ; beta-catenin-interacting protein . the experiments were performed thrice and results represent the average (b) and representative findings are shown (a). fig. . effect of hypothermia on gene expression of er chaperones (a), xbp mrna splicing (b), er stress sensors (c), apoptosis- associated factors (d) and autophage-associated factors (e). pc cells were incubated under control conditions ( ) or hypothermia℃ ( ) for day. gene expressions were determined by rt℃ -pcr by conditions described in materials and methods (a, d, e). the product of xbp -pst digestion was subjected to electrophoresis on the agarose gel (b). both cleavage of atf- and phosphorylation elf α were assessed by western blotting (c). the experiments were performed thrice and results represent the average and representative findings are shown. bip; binding immunoglobulin protein, canx; calnexin, pdi; protein disulfide isomerase, atf ; activating transcription factor , phosph-elf α; phosphorylation of eif α, bak ; bcl -antagonist/killer , bcl- ; b-cell lymphoma , lc ; microtubule-associated protein light chain α, beclin; coiled-coil myosin-like bcl -interacting protein. a b c a d b e - - alone and cells treated with hypothermia together with ischemia, to verify whether hypothermia induced cells were related to ischemia. as shown in the fig. , ctnnbip gene expression significantly decreased to about . fold compared to its control. at this point there is no data to support that ctnnbip gene expression is related to ischemia, or especially associated with hypothermia. how- ever, the result shown in fig. demonstrated that hypo- thermia decreasingly modulated ctnnbip mrna expres- sion under ischemia. we have tested whether hypothermia controlled er chaperones (bip, calnexin and pdi) (braakman and bulleid, ), the downstream-factors of er stress sensors (xbp , eif α and atf ) (lee and ozcan, ), apoptosis-associated factors (bak and bcl- ) (lovat et al., ) and autophage-associated factors (lc and beclin) (jin and klionsky, ). cells exposed to hypo- thermia had no changes in er chaperones gene expression (fig. a), apoptosis-associated factors (fig. d) and autophage-associated factors (fig. e). accumulation of un-/misfolded proteins in the er lumen triggers an er stress signal pathway through er stress sensors. it is well known that, upon er stress, releasing bip from the er luminal stress sensors cleaves atf α, xbp mrna splicing and phosphorylation of eif α (shore et al., ). although no spliced xbp (fig. b) was observed, both the cleavage of atf- and phosphorylation eif α was clearly increased (fig. c). the result of fig. showed that hypothermia controlled ctnnbip mrna expression through the activation of down-stream er stress sensors, i.e. cleavage of atf- and phosphorylation eif α, but not er chaperones. in summary, the present study was the first to demonstrate that hypothermia induced ctnnbip mrna. additionally, its expression was further decreased to less than control levels under conditions of ischemia. ctnnbip gene expression by hypothermia was associated with unfolded protein response (upr); and activation of er stress sensors, especially higher phosphorylation of eif α and atf cleavage but unchanged er chaperone expression. no alternative mrna expression of apoptosis- and autophage- associated factors, was observed in cells treated with hypothermia. our findings suggested that hypothermia decreased ctnnbip gene expression under ischemia, which may provide new insight into the possibility of hypothermia treatment for ischemia, and may help in the development of novel methods for easy and quick diagnosis of neurodegenerative disorders, including ischemia and hypoxia. acknowledgements this work was supported by research fund of chungnam national university ( ). references al-fageeh mb, smales cm. cold-inducible rna binding protein (cirp) expression is modulated by alternative mrnas. rna. . : - . braakman i, bulleid nj. protein folding and modification in the mammalian endoplasmic reticulum. annu rev biochem. . : - . drury pp, gunn er, bennet l, gunn aj. mechanisms of hypo- thermic neuroprotection. clin perinatol. . : - . jin m, klionsky dj. regulation of autophagy: modulation of the size and number of autophagosomes. febs lett. . : - . kalogeris t, bao y, korthuis rj. mitochondrial reactive oxygen species: a double edged sword in ischemia/reperfusion vs preconditioning. redox biol. . : - . kristián t. metabolic stages, mitochondria and calcium in hypoxic/ischemic brain damage. cell calcium. . : - . lee j, ozcan u. unfolded protein response signaling and metabolic diseases. j biol chem. . : - . lemmers pm, dix lm, toet mc, van bel f. limited short-term prognostic utility of cerebral nirs during neonatal thera- peutic hypothermia. neurology. . : - . lovat pe, oliverio s, corazzari m, ranalli m, pearson ad, melino g, piacentini m, redfern cp. induction of gadd and bak: novel molecular targets of fenretinide-induced apoptosis of neuroblastoma. cancer lett. . : - . shore gc, papa fr, oakes sa. signaling cell death from the endoplasmic reticulum stress response. curr opin cell biol. . : - . tago k, nakamura t, nishita m, hyodo j, nagai s, murata y, adachi s, ohwada s, morishita y, shibuya h, akiyama t. - - inhibition of wnt signaling by icat, a novel beta-catenin- interacting protein. genes dev. . : - . yong yp, saunders j, abisi s, sprigg n, varadhan k, macsweeney s, altaf n. safety of carotid endarterectomy following thrombolysis for acute ischemic stroke. j vasc surg. . : - . zhang h, li l, xu gy, mei yw, zhang jj, murong sx, sun sg, tong et. changes of c-fos, malondialdehyde and lactate in brain tissue after global cerebral ischemia under different brain temperatures. j huazhong univ sci technol. med sci. . : - . south texas eolian system--model of coastal eolian processes: abstract association round table slope in the alaminos canyon area, gulf of mexico, indicate sand input from the ancestral colorado-brazos and mississippi river systems. the clay minerals in the area were derived from indeterminate sources and were incorporated in coarse samples through resuspension of former sediment. vermiculite, as well as tubular hallaysite, were identified in clay samples. the first mineral is unreported in the northwest gulf and the latter is only known from the mississippi delta in the northwest gulf area. the "hummocky" nature of the bathymetry in the area re- sulted from salt diapirism and scouring by tractive and/or density flow. sand-size sediment was transported to the area from river systems by longshore drift during the holocene transgression or through channels still identifiable on the pres- ent continental shelf the lineation of one of these features, the outer colorado-brazos channel, is probably due to salt tecton- ics and not the result of a barrier spit as previously reported. berg, r. r., dept. geology, texas a&m univ., college station, tex. oil-column calculations in stratigraphic traps oil columns can be calculated for simple stratigraphic traps if the rock and fluid properties are known or can be estimated. because oil migration is prevented by capillary pressure in small pores of the trap fades, direct measurements of capillary pressure allow oil columns to be calculated, but such measure- ments are rare. an alternative is to determine pore size from porosity and permeability data using an empirical equation, and then to compute the capillary pressure by an estimate of fluid properties. an example of oil-column calculation is from the milbur field, burleson county, texas, a lower wilcox stratigraphic trap. using core analysis from a nearby well, an oil column of - ft would be expected for the trap, and this estimate agrees reasonably well with an actual oil column of - ft for the field. the most important part of such calculations is the real- ization that the trapping facies itself can have significant poros- ity and permeability and yet form an effective barrier to oil migration. the result is that the best reservoir may occur down- dip from dry holes with porous water-bearing sandstone and oil shows, rather than updip at the pinchout. birdseye, h. s., consultant, albuquerque, n.m. geothermal power in the southwest in this era of great concern over the environment and the energy crisis, much attention is being directed toward geother- mal power as a partial panacea for both predicaments. of approximately , known geothermal occurrences in the uaited states, most of which are in and west of the rockies, a relatively small percentage are classified as dry steam reservoirs, capable of producing hot unsaturated steam which poses mini- mal efiluent disposal problems. others, such as the salton sea field in southern california, pose critical waste brine difficulties, which will probably be solved only by reinjection. a major geothermal field, e.g., the geysers in northern california, is expected to produce steam adequate to generate from , to , megawatts of electricity, with -year gross revenue from steam sales on the order of $ billion. there are known geothermal occurrences in the southwestern states of texas (less than a dozen). new mexico ( ), arizona ( ), nevada ( ), and southern california (about ). it is likely that additional geothermal prospects will be developed by the use of sophisticated geologic mapping, coupled with such geophysical methods as studies of temperature-gradients, mi- croseisnris and ground noises, resistivity, and remote sensing, and chemical methodology useful in determining maximum water temperature in the system and the age of that water. bouma, a. h., dept. oceanography, texas a&m university, college station, tex. recent and ancient turbidites and contourites fossil turbidites have been recognized and described from many areas all over the world. a turbidite model, comprised of a fixed succession of sedimentary structures, was established a decade ago and seems to be usable, although some changes have been suggested. turbidites are generally assumed to be deposited by turbidity currents, but the presence of these currents in the marine realm has not been definitely established. submarine canyons presum- ably are the major, if not only, important transport route for moving "shallow" water material to "deeper" basins. questions arise about the origin of turbidity currents when studying can- yons in which gradual filling followed by sudden emptying has occurred. the material in the canyon head moves downward slowly, comparable to glaciers. besides this slow sliding, trac- tion currents and debris flow have been suggested. where tur- bidity currents start, and if they absorb the slow moving can- yon fill, are questions that cannot be answered yet. other prob- lems are the relation between fluxoturbidites, or gravities, and turbidites, and the use of the terms "proximal" and "distal" turbidites. in comparing recent turbidites with ancient ones, many dis- crepancies appear, most of which can be euminated by consid- ering the influence of primary consolidation on segmentary structures. studies indicate that the use of electrical logging and seismic records do not allow detailed interpretation of deposits such as turbidites. the resolution of the records is not fine enough, although their application for basin analyses and overall trends is necessary. recently a new genetic term, "contourites," was introduced for sediments redeposited by contour currents. recent and ancient contourites are compared with turbidites and only mi- nor differences exist. a combination of parameters may allow a distinction between the two types and it is possible that both can be found in the same area. brown, l. f., jr., bur. econ. geology, univ. texas at aus- tin, austin, tex. south texas eolian system—model of coastal eolian processes few oil and gas reservoirs have been interpreted as sands deposited within eolian depositional systems. eolian facies may, however, be more common in ancient basins than heretofore recognized. continued documentation of holocene eolian sys- tems, such as the south texas system, provides a model for reevaluating the genesis of numerous unfossihferous, well- sorted blanket sand bodies, many of which are associated with ancient, paralic depositional systems. pleistocene paralic depositional systems along the south texas coast dictate the natiu'e and distribution of facies pat- terns, environments, and processes exhibited by the overlying holocene south texas eolian system. a dominant southeast wind, high summer temperatures, and high rainfall deficiency combine with an abundant supply of pleistocene sand to pro- vide the proper framework widiin which extensive eolian defla- tion and dune migration can occur. eolian lobes are supplied with sand from pleistocene barrier- strandplain facies and fluvial meanderbelt deposits. loess sheets are derived from distant lobes, as well as from deflation of local pleistocene deltaic and fluvial facies. deflation of thick pleistocene fluvial-deltaic sand facies is commonly stabilized when erosion reaches the shallow groundwater table. maximum deflation occurs on the upwind, coastward margin of the sys- tem, especially where only thin pleistocene paralic sands are available to supply dune trains; mud deflated by strong off- association round table shore winds is moved into clay dune complexes and eventually carried downwind to develop loess sheets. this extensive up- wind deflation of the system is accompanied by windward accreting clay-sand ridges with nuclei composed of either beach-ridge remnants of a pleistocene barrier-strandplain sys- tem or remnants of inter-blowout areas developed during early phases of the deflation of the coastward margin of the system. principal source of sand and loess is, therefore, local, repre- senting reworking of underlying, older sands. a sand source resulting from longshore convergence and inland transport from padre island accounts for only the minor, local infllling of laguna madre in the land-cut area, and is not the principal source of eouan sand throughout the system. facies fabric within pleistocene depositional systems provides principal con- trol of environments, sedimentary processes, and resulting fa- cies within the subsequent eolian system. bruce, c. h., mobil oil corp., corpus christi, tex. pressured shale and related sediment deformation—mecha- nism for development of regional contemporaneous faults regional contemporaneous faults of the texas coastal area are formed on the seaward flanks of deeply buried unear shale masses characterized by low bulk density and high fluid pres- sure. from seismic data these masses have been observed to range in size up to mi wide and , ft vertically. these features, aligned subparallel with the coast are en echelon or branching in pattern, and represent residual masses of under- compacted sediment between sand-shale depoaxes in which greater compaction has occurred. most regional contemporane- ous fault systems in the texas coastal area were formed during times of shoreline regression when the duration of fault devel- opment extended over short periods of geologic time, and where comparatively simple down-to-the-basin fault patterns were developed. in cross-sectional view, faults in these systems flatten and converge at depth to planes related to fluid pressure, and form the seaward flanks of underlying shale masses. data indicate that faults formed during time of shoreline regression were developed primarily through differential compaction of adjacent sedimentary masses. these faults die out at depth near the depoaxis of the sand-shale section. in areas where subsidence exceeded the rate of deposition, gravitational faults developed where basinward sea-floor incli- nation was estabushed in the immediate area of deposition. some of these faults became bedding plane type when the incunation of basinward-dipping beds equaled the critical slope angle for gravitational slide. fault patterns developed in this manner are comparatively complex and consist of numerous antithetic faults and related rotational blocks. nondepositional (structural) faults are common on the land- ward flanks of deeply buried shale masses. many of these faults dip seaward and intersect the underlying low-density shale at relatively steep angles. conclusions derived from these observations support the concept of regional contemporaneous fault development through sedimentary processes where thick masses of shale are present and where deep-seated tectonic effects are minimal. butler, e. a., and h. w. simpson, atlantic richfield co., dallas, tex. dlversnt-equitability analysis as p a l e o e c o l o o i c t o o l diversity-equitability analysis of microfaunal data as used by beerbower and jordan shows promise of being a rapid and useful technique for mapping paleoenvironmental gradients. it may even provide a more satisfactory definition of environmen- tal boundaries than biofacies analysis based on taxonomic com- position. faunal diversity is calculated as shannon's information the- ory average uncertainty measure. using this diversity measure, a few equally common taxa can yield as high a diversity index as many unequally common taxa. lloyd and ghelardi's equita- bility index may be used to separate these two diversity compo- nents and refine seemingly homogeneous data. recent microfaunal data from barnstable harbor, massa- chusetts, and the northern gulf of mexico have been subjected to diversity-equitabihty analysis. from barnstiible harbor, con- tours based on the equitability index can be related rather clearly to tidal action within the harbor. a diversity-equitability plot of published holocene gulf of mexico data reveals that some environments may be characterized by a unique d / e range. although these results must be considered preliminary, an analysis of parts of the lower miocene sequence in block field, high island area, oflshore texas, shows that the techni- que merits further consideration and is potentially a very useful tool for both identifying and mapping ancient environments. clark, h. c , dept. geology, rice univ., houston, tex. paleomagnetism of late pleistocene-holocene sediments, gulf of m e x i c o detailed paleomagnetic studies have been made on sedi- ment cores selected along north-south lines in the eastern and western gulf of mexico. the piston cores were sampled at - cm intervals immediately upon extrusion and measurements of natural remanent magnetization (nrm) were made using a hz spinner magnetometer. excursions of the geomagnetic field are recorded at levels in many cores. extrapolation of the zy boundary in the western gulf indicates that the younger feature is between . and . x ' years bp, and is consistent with the age determination of the laschamp event. dates are not available for the eastern gulf cores, but the depth of the paleo- magnetic feature correlates with the expected sedimentation rates. the older feature is less distinct and further extrapolation of the zy boundary places it between . and . x \(fi years bp. this age is within the range of a geomagnetic feature that is not the laschamp. these re ".ults show that with extreme care, paleomagnetic measureme its may be used as a stratigraphic tool in the gulf of mexico. several points should bi considered. first, because of the high sedimentation rates, the yotmg features described herein are the only ones expected in piston cores from this region. second, direction scatter is quite pronounced in the upper / m and lower few centimeters of several cores. corre- lations at these levels are difficult. finally, as measurement of the geomagnetic features described lasted for only a short time and did not traverse a full °, dense sampling is recom- mended to assure their definition. crandall, k. h., consulting geologist, piedmont, cauf economic and other factors affecting petroleum exploration there is today almost universal agreement that we are facing a potential energy crisis, both imminently in the u.s. and possibly worldwide after the turn of the century. all studies of energy supply and demand indicate such tremendous growth in demand tiiat conventional sources will be hard pressed to sup- ply it. the short-range aimual growth rate in domestic and free- world demand for petroleum is estimated at % and / % respectively, resulting in million and million bbl/day total demand in . by u.s. demand will be nearly million bbl and free foreign need nearly miuion bbl/day. the areas which will supply this demand, especially for fhe u.s., ark quite imcertain because of the bewildering variety of poutical, legal, and environmental factors—as contrasted with purely economic ones—which will be of critical influence. therefore, it is difficult to forecast the areas and the amounts and costs of exploration and development, as well as prices and earnings. one thing is certain, however, there will be a growing short- age of domestic crude and an increasing dependence on foreign suppues. both the cost and dependabiuty of the latter are questionable in view of political considerations and the policies and actions of opec. regulatory compliance and environmental benefit analysis of combined heat and power (chp) systems in taiwan energies , , - ; doi: . /en energies issn - www.mdpi.com/journal/energies article regulatory compliance and environmental benefit analysis of combined heat and power (chp) systems in taiwan wen-tien tsai graduate institute of bioresources, national pingtung university of science and technology, pingtung , taiwan; e-mail: wttsai@mail.npust.edu.tw; tel.: + - - - ; fax: + - - - received: october ; in revised form: january / accepted: january / published: january abstract: the energy conservation achieved by utilizing waste heat in the energy and industrial sectors has became more and more important after the energy crisis in the s because it plays a vital role in the potential energy-efficiency improvement. in this regard, cogeneration (combined heat and power, chp) systems are thus becoming attractive due to the energy, economic, and environmental policies for pursuing stable electricity supply, sustainable development and environmental pollution mitigation in taiwan. the objective of this paper is to present an updated analysis of chp systems in taiwan during the period from to . the description in the paper is thus based on an analysis of electricity supply/consumption and its sources from chp systems during the past two decades, and centered on two important regulations in compliance with chp systems (i.e., energy management law and environmental impact assessment act). based on the total net power generation from chp systems (i.e., , gwh) in , it was found that the carbon dioxide reduction benefits were estimated to be around , gg. keywords: combined heat and power; electric power; compliance regulation; environmental benefit . introduction taiwan is a small and densely populated island country (land area: , km ; population: million) in the far east (asia) with limited natural resources. in the past two decades, the rapid industrialization and economic development have caused a high dependence on imported energy, which increased from . % in to . % in [ ]. meanwhile, an increase in the total carbon dioxide (co ) emissions from . × tons in to . × tons in proportionally open access energies , occurred in parallel with the energy supply [ ], . million kiloliters of oil equivalent (kloe; kloe = . × j) in in contrast to . million kloe in . as a result, the executive yuan of taiwan adopted several regulatory and financial measures in the past two decades to encourage energy saving and renewable energy development. in this regard, the taiwan government approved “framework of taiwan’s sustainable energy policy” in to pursue the following targets [ ]: ■ improving energy efficiency by more than % per annum, so that energy intensity will decrease % by when compared with the level in ; ■ reducing nationwide co emissions by developing clean energy, so that total emissions could return to its level between and , and further reduced to the level in . the energy utilization of waste heat from energy-intensive process industries (such as steel, paper, chemicals, petroleum, glass, and cement) and publicly-serviced utilities (especially in municipal solid waste incineration plants) has received much attention after the energy crisis in the s because it plays a vital role in the energy-efficiency improvement potential. combined heat and power (chp), also known as cogeneration, is the simultaneous production of electricity and heat in one single process for dual output streams so as to greatly increase the process efficiency and decrease energy costs [ ]. also, chp systems can avoid transmission losses in the delivery of electricity (power grid) from the central station power plant, thus decreasing the impact of outages and improving power quality for sensitive equipment. in addition to the energy saving and cost saving, the benefits of chp system are mainly from lower air pollutants emissions to the atmospheric environment, thus reducing the greenhouse gases (i.e., co , ch and n o) and air toxics (i.e., sox, nox and hg) emissions, which contribute to global warming and air quality, respectively. a previous paper [ ], only focused on comprehensive descriptions of the electricity supply and consumption during the period of – and governmental regulations for promoting industrial waste (i.e., pulp sludge, scrap wood, sugarcane bagasse, textile sludge, and scrap plastics) as energy sources, and centered on preliminary benefit analysis in the greenhouse gases reduction as a result of chp system. in this study, the open-access documents officially published by the taiwan central government were used to provide the updated and analytical information about the energy utilization of using chp system in the past two decades ( – ). the main subjects of this paper covered the following key elements: ■ current status of electricity supply and consumption; ■ current status of electricity from chp system; ■ regulatory compliance with chp system; ■ preliminary benefit analysis from chp system. . current status of electricity supply and consumption it is well known that a stable electricity supply plays a core role in the economic development and level of living. prior to the mid- s, the taiwan power company (taipower, abbreviated to tpc), which is one of the government-owned enterprises, was entrusted with development, generation, supply, transmission/distribution, and marketing of electric power in the taiwan area. under the government policy on deregulation of the electric power sector and the energy saving in consideration energies , of economic and environmental benefits, privately industrial plants from the energy-intensive industries (e.g., steel, paper and pulp, petrochemical and cement manufacturing) and public service utilities (e.g., municipal solid waste incineration plants) have been encouraged to install chp systems and to sell their surplus electricity to taipower for its own distribution. in order to maintain a stable electricity supply, the central competent authority (i.e., ministry of economic affairs, moea) has further promoted the opening of the electric power market to independent power plants (ipp) in four stages during the years of – . as seen in figure [ ], reliance on taipower’s electricity supply based on installed capacity was on the decreasing trend due to the nation’s energy policy on efforts to diversify electric power sources. on the other hand, however, the reliances on ipp and chp systems were on the increasing trend. with respect to the electricity supply (production) and consumption in the past two decades ( – ), some notable points were further addressed as follows [ ]: ■ electricity production (power generation) grew from . terawatt-hour (twh) , to . twh in and . twh in . on average, an annual increase was about . % in the two past decades. of the total electricity production in , taipower’s hydro power comprised . twh ( . %), thermal power . twh ( . %; including coal shared . %, oil . %, and lng . %), nuclear power . twh ( . %), wind power . twh ( . %), chp . twh ( . %), and ipp . twh ( . %); ■ electricity consumption went from . twh in to . twh in and . twh in , an average annual increase of . %. classified by sector, energy sector (own use) used . twh ( . %) of electricity in , industrial sector consumed . twh ( . %), transportation sector occupied . twh ( . %), agricultural sector amounted to . twh ( . %), services sector accounted for . twh ( . %), and residential sector took . twh ( . %); ■ the percent reserve margin also saw an increasing trend from . % in to . % and . % in and , respectively. it should be noted that the peak load in reached a record , mw (megawatt). figure . installed capacity of power generation in the past two decades ( – ) in taiwan. . current status of electricity production in chp systems the energy intensity or energy use intensity is usually defined as a measurement of the energy efficiency in producing a given level of output or activity. in this regard, chp systems are thus energies , becoming attractive in the energy and industrial sectors of taiwan. as shown in figure , there has been a distinct improvement in energy intensity since , from . loe per thousand nt dollars (based on constant prices) in , and then reducing to . loe per thousand nt dollars in [ ]. the percentage of the average improvement is about . %. under the authorization of the energy management law, the main strategies include: implementing an energy auditing and guidance system for large energy users, and promoting voluntary energy-conservation programs by the targeted energy users. figure . variations of energy intensity in taiwan in the past decade. to promote chp system for the purpose of upgrading efficient utilization of energy in the process industries, the central competent authority implemented a compliance regulation (“measures for implementing the cogeneration system”) on july , . thereafter, total installed capacity of chp systems was on an increasing trend as seen in figure [ ]. by the early of , all chp systems in the taiwan area were listed in table [ ]. some important features in table and figure are pointed out as follows: ■ total number of cogeneration systems was , of which were from public services (including municipal solid waste incineration plants and five sanitary landfills), were from petrochemical plants, were from paper and pulp plants, nine were from synthetic fiber plants, eight were from food plants (including four sugar refineries, which utilize their agrowaste bagasses as auxiliary fuel for generating steam and electricity), six were from plastics plants, and were other plants; ■ total installed capacity of chp systems amounted to , mw, of which , mw ( . %) from petrochemical plants, mw ( . %) from plastics plants, mw ( . %) were from synthetic fiber plants, mw ( . %) were from public services, mw ( . %) were from iron and steel plant, mw ( . %) were oil and oil refining plants, and mw ( . %) were from other plants; ■ in the past two decades ( – ), annually average growth of total installed capacity from chp systems was about . % according to the data in figure . obviously, the annual growth rate was larger than that (i.e., . %) of total electricity supply at the same period as described above. energies , figure . installed capacity of chp system in taiwan during the – period. table . updated statistics of installed capacity of qualified chp systems in taiwan a. industrial classification no. of chp plant installed capacity (kw) percentage (%) food b , . synthetic fiber , . textile , . paper and pulp , . petrochemical , , . plastics , . basic chemical , . oil and oil refining , . cement , . iron and steel , . gas fuel supply . cogeneration (chp) , . public service c , . electronic , . total , , notes: a source [ ]: the statistical data was updated on february . b including sugar mills and food processing plants; c including msw-to-power plants and biogas-to-power plants. furthermore, a preliminary comparison of the installed capacity statistics of chp of japan and korea was addressed to reflect seriously on the energy saving management in the neighboring countries. by the end of , total installed capacity of chp systems in japan amounted to about , mw, of which , mw ( %) was from the industrial sector, and , mw ( %) from the commercial and residential sectors. the former mainly includes chemical, machinery and steel industries. the latter was mostly used by hospitals, hotels, buildings and gymnasiums. in recent years, the chp in japan has been promoted to adopt low-carbon technologies like gas-fired and fuel cell systems. by contrast, total installed capacity of chp systems in korea totaled around , mw in . this country is making chp more efficient by using district heating and cooling (dhc) in the industrial sector, and more climate-friendly by fuel cell system in the commercial and residential sectors. energies , . regulatory compliance with chp systems according to the national energy statistics by the central competent authority [ ], the total energy consumption in amounted to about . million kloe, of which . % was used in the energy and industrial sectors. as mentioned above, chp systems are the simultaneous production of electricity and heat in one single process for dual output streams so as to maximize its thermal efficiency of up to %. however, about % of the energy potential contained in the fed fuel can be converted into electricity in the conventional power system. in order to improve the performance efficiency in the industrial and energy sectors of taiwan, there are two important regulations in compliance with chp systems: energy management law and environmental impact assessment act. . . energy management law in response to the energy crisis in the s, the taiwanese government first promulgated the energy management law (eml) in august , which was recently revised on july . the principal purpose of the law is to aim at rational and efficient utilization of energy, including fuels and waste. according to the newly revised eml, important features concerning the aspects of chp systems are stipulated in article , which was summarized as follows: ■ the energy user, which generates the amount of steam set up by the central competent authority, should install the cogeneration system. as a result, the referred energy users include industrial (electronics, chemicals, steel, textile, paper and pulp, cement, food, and refinery), energy (fired power and cogeneration), waste management (i.e., waste incineration) and other non-manufacturing plants; ■ the energy user, which meets the levels of effective thermal ratios and total thermal efficiencies set up by the central competent authority in its chp system, may ask the local vertical integrated utilities (e.g., taipower) to purchase its excess electricity and supply backup electricity needed for its system maintenance or at the time of system breakdown; ■ the central authority shall stipulate an implementation regulation regarding the rates for the purchase of excess electricity, the levels and verification of effective thermal ratios and total thermal efficiencies, the tie-in between the systems of the energy user and the vertical integrated utilities, the method of purchasing electrical energy, the rates for electricity and backup electricity purchased, and the duration of the obligation to purchase excess electricity by the vertical integrated utilities. in this regard, the current feed-in tariff price for purchasing surplus cogeneration electricity is connected with the electricity selling price of taipower, which takes into account the power generation cost or power supply capacity for semi-peak hour in the promulgated the regulation (i.e., “measures for implementing the cogeneration system”, described later). the regulatory measure will indirectly make the feed-in tariff price of excess cogeneration electricity more reasonable. under the authorization of the law, the ministry of economic affairs (moea) has promulgated the relevant regulation (i.e., “measures for implementing the cogeneration system”) since september . according to the provision of the regulation, a qualified chp system is defined as referring to the registered energy user and its levels of effective thermal ratio [= effective heat output ÷ (effective energies , heat output + effective electricity output)] ≥ % and total thermal efficiency [= (effective heat output + effective electricity output) ÷ heating value of fuel)] ≥ %, or the registered system specified in treating wastes. also, the registered energy user should establish its own energy audit system (e.g., installing electricity meter to record daily electricity usage, reporting the monthly statistics to the central competent authority, performing the energy management by an qualified and registered personnel) in conjunction with objectives for energy conservation and the implementing plan which shall be carried out upon approval by the central competent authority. in , the central competent authority selected qualified power plants with chp systems to carry out inspection and guidance for their total thermal ratios and effective thermal efficiencies [ ]. with regard to efficiency inspection, eight chp plants that completed the inspection were qualified under article of the regulation, with the total thermal efficiency of % and effective thermal ratio of %. . . environmental impact assessment act the preventative approaches towards environmental protection and pollution prevention started in the end of s in taiwan. as a consequence, the introduction of environmental impact assessment (eia) could significantly strengthen the prevention and mitigation of adverse impacts at the early stage of development activities. article of environmental impact assessment act (eiaa), first promulgated in december and recently revised in january , authorizes the central competent authority to conduct eia for the development activities that are likely to cause adverse impacts on the environment. further, the resulting regulations (i.e., “working guidelines for environmental impact assessment of development activities” and “standards for determining specific items and scope of environmental impact assessment for developing activities”) promulgated by the central authority under the authorization of eiaa requires those prescribed development activities that eia shall be conducted, and shall install chp system to increase the energy use efficiency and provide the thermal energy in the industrial parks if it is feasible. for example, the eia shall be conducted for the chp systems of thermal power plants, which are located in land for non-city use and the use of gas fuel over , kw (power capacity), or oil, coal and other fuels over , kw (power capacity). however, the installed capacity of a multiple cycle generating unit with no added auxiliary fuel can be increased . times. comparing the data in table , the installed chp system capacity in was significantly larger than with that in , implying that the regulatory policies discussed should have an important impact on the decision to install chp system in the industrial sector. more importantly, this progress, thereby having a significant effect on decentralization of electricity power sources and optimization of power supply reliability, should be also due to the economic incentive measures including subsidiary grant/grant, feed-in tariff, tax relief and low-interest loan, etc. . preliminary benefit analysis from chp systems concerning the benefits of mitigating greenhouse gases (ghg) emissions to the environment, a simple method (tier method) adopted by the intergovernmental panel on climate change (ipcc) was used to estimate equivalent co emissions mitigation from the chp systems for electricity generation (assumed in the present work) [ ]. the ipcc methodology is based on the net quantities of energies , electricity generated and average default emission factor (def). therefore, the equivalent mitigations of co emissions from the chp systems for electricity generation in comparison with ghg emissions from the fossil fuel-fired power plant can be calculated by multiplying levels of chp activity (power generation in kwh) with def (kg co /kwh). based on the statistical weighting calculation by the state-owned company in taiwan (taipower co.), the default value in terms of the equivalent amount of co produced per kwh is about . kg co /kwh. using the reported data on total net power generation of about , gwh in from the chp systems [ ], the equivalent mitigation of co (gg) from the chp systems for electricity generation was thus calculated as given below: equivalent mitigation of co (gg) = . kg/kwh × , gwh × kwh/gwh × − gg/kg ≈ , gg. . conclusions in taiwan, the basic principle of a sustainable energy policy is to establish a high efficiency, high value-added, low emission, and low dependency energy consumption and supply system. in this regard, chp systems have been promoted through a regulatory framework under the energy management law in the past two decades. in , total installed chp system capacity amounted to about , mw. also, total net power generation is about , gwh from the chp systems during the same period. as a result, the quantitative benefit from electricity supply by all installed chp systems was preliminarily calculated to be around , gg/year. to encourage the investment in chp systems as an energy-efficiency improvement and a measure for the reduction of greenhouse gases emissions, and also achieve the government goal (i.e., total installed capacity reached , mw) in , the renewable energy development act, which has been passed in june , will further promote the combustible biomass residues to co-combust with fossil fuels in the process industries and thermal power plants with chp systems. this is due to the fact that the surplus electricity shall be sold to the state-owned company (taipower) at an officially designated rate. acknowledgments this research was partly supported by nsc (national science council), taiwan, under contract nsc - -s- - (technical talent cultivation for bio-energy industry in southern taiwan). conflict of interest the author declares no conflict of interest. references . energy statistics handbook— [in chinese]; bureau of energy (boe): taipei, taiwan, . . statistics on emissions of co from combustion and its analysis [in chinese]; bureau of energy (boe): taipei, taiwan, . . huang, y.h.; wu, j.h. energy policy in taiwan: historical developments, current status and potential improvements. energies , , – . . turner, w.d. cogeneration. in handbook of energy efficiency and renewable energy; kreith, f., goswami, d.y., eds.; crc press: boca raton, fl, usa, ; pp. : – : . energies , . tsai, w.t.; hsien, k.j. an analysis of cogeneration system utilized as sustainable energy in the industrial sector in taiwan. renew. sustain. energy rev. , , – . . statistical database on cogeneration system; bureau of energy (boe): taipei, taiwan. available online: http://web .moeaboe.gov.tw/ecw/populace/content/whandmenufile.ashx?menu_id= (accessed on september ). . counseling to promote cogeneration system setup and economic analysis study in ; taiwan research institute (tri): taipei, taiwan available online: http://www.tri.org.tw/english/ research_e/research .php?id= ( accessed on december ). . tsai, w.t. analysis of the sustainability of reusing industrial wastes as energy source in the industrial sector of taiwan. j. clean. prod. , , – . © by the authors; licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution license (http://creativecommons.org/licenses/by/ . /). the genomic landscape of renal oncocytoma identifies a metabolic barrier to tumorigenesis article the genomic landscape o f renal oncocytoma identifies a metabolic barrier to tumorigenesis graphical abstract highlights d type renal oncocytoma may precede eosinophilic chrcc d mitochondrial defects disrupt golgi organization and trafficking d mitochondrial accumulation in oncocytomas is due to defective elimination d impaired mitochondrial function is a barrier to tumorigenesis joshi et al., , cell reports , – december , ª the authors http://dx.doi.org/ . /j.celrep. . . authors shilpy joshi, denis tolkunov, hana aviv, ..., shridar ganesan, chang s. chan, eileen white correspondence chanc @cinj.rutgers.edu (c.s.c.), epwhite@cinj.rutgers.edu (e.w.) in brief mechanisms that restrict tumors to benign disease inform approaches to cancer therapy. joshi et al. report that genetic defects in mitochondrial respiration in benign oncocytomas block trafficking and activate p , limiting tumor growth to benign disease. mailto:chanc @cinj.rutgers.edu mailto:epwhite@cinj.rutgers.edu http://dx.doi.org/ . /j.celrep. . . http://crossmark.crossref.org/dialog/?doi= . /j.celrep. . . &domain=pdf cell reports article the genomic landscape of renal oncocytoma identifies a metabolic barrier to tumorigenesis shilpy joshi, , denis tolkunov, , hana aviv, abraham a. hakimi, ming yao, james j. hsieh, shridar ganesan, , chang s. chan, , ,* and eileen white , ,* rutgers cancer institute of new jersey (cinj), little albany street, new brunswick, nj , usa department of pathology and laboratory medicine, rutgers robert wood johnson medical school, one robert wood johnson place, meb , new brunswick, nj , usa urology service, department of surgery, memorial sloan kettering cancer center, york avenue, new york, ny , usa human oncology and pathogenesis program, memorial sloan kettering cancer center, york avenue, new york, ny , usa department of medicine, robert wood johnson medical school, rutgers, the state university of new jersey, robert wood johnson place, new brunswick, nj , usa department of molecular biology and biochemistry, rutgers university, allison road, piscataway, nj , usa co-first author *correspondence: chanc @cinj.rutgers.edu (c.s.c.), epwhite@cinj.rutgers.edu (e.w.) http://dx.doi.org/ . /j.celrep. . . this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). summary oncocytomas are predominantly benign neoplasms possessing pathogenic mitochondrial mutations and accumulation of respiration-defective mitochon- dria, characteristics of unknown significance. using exome and transcriptome sequencing, we identified two main subtypes of renal oncocytoma. type is diploid with ccnd rearrangements, whereas type is aneuploid with recurrent loss of chromosome , x or y, and/or and , which may proceed to more aggressive eosinophilic chromophobe renal cell carcinoma (chrcc). oncocytomas activate adenosine monophosphate-activated protein kinase (ampk) and tp (p ) and display disruption of golgi and autophagy/lysosome trafficking, events attributed to defective mitochondrial function. this suggests that the genetic defects in mitochondria activate a metabolic checkpoint, producing auto- phagy impairment and mitochondrial accumulation that limit tumor progression, revealing a novel tu- mor-suppressive mechanism for mitochondrial inhi- bition with metformin. alleviation of this metabolic checkpoint in type by p mutations may allow pro- gression to eosinophilic chrcc, indicating that they represent higher risk. introduction altered metabolism in cancer that promotes the fermentation of glucose was proposed more than years ago by otto warburg to originate from respiratory system damage (warburg, ). only recently with the discovery of cancer driver mutations in nuclear genes encoding mitochondrial tricarboxylic acid (tca) cell re cycle enzymes have we begun to unravel the underlying onco- genic functions linked to altered metabolism (ward and thomp- son, ). moreover, it is now clear that many oncogenic events common in cancer indirectly regulate cellular metabolism (van- der heiden et al., ). these metabolic alterations may provide substrates and energy necessary for cell growth, promote anti- oxidant defense, and produce signals that alter gene expression and drive pro-oncogenic signaling pathways. these discoveries are revealing new approaches to cancer therapy that target metabolic functions important for tumorigenesis. one underex- plored area within the sphere of metabolic alterations in cancer is represented by the tumor type oncocytoma. oncocytomas are rare, predominantly benign neoplasms mostly of epithelia that have inactivating mutations in mitochon- drial genome-encoded enzymes or control regions that cause respiration defects. oncocytomas are also characterized by the dramatic accumulation of these defective mitochondria (gasparre et al., ). whether the mitochondrial impairments are functionally neutral, promote tumor growth as warburg envi- sioned, or to the contrary are a liability is unknown. it is also un- clear why defective mitochondria accumulate and if this plays any role in disease. oncocytomas may represent an evolutionary dead end or an intermediate that progresses to more aggressive cancer. identifying mechanisms that restrict some tumors such as these to benign disease can inform novel approaches to can- cer therapy. mitochondria are essential for eukaryotic cell function. cells contain hundreds of mitochondria, with their numbers controlled by both a transcription program of biogenesis (wallace, ) and removal of defective mitochondria through mitophagy, a selective form of autophagy (youle and narendra, ). thus, the presence of tumor cells with the accumulation of defective mitochondria suggests increased biogenesis, possibly as a compensatory mechanism (simonnet et al., ), or an under- lying defect in removal by mitophagy (guo et al., b). as autophagy deficiency in genetically engineered mouse models for krasg d- and brafv e-driven lung cancers converts ports , – , december , ª the authors mailto:chanc @cinj.rutgers.edu mailto:epwhite@cinj.rutgers.edu http://dx.doi.org/ . /j.celrep. . . http://creativecommons.org/licenses/by-nc-nd/ . / http://crossmark.crossref.org/dialog/?doi= . /j.celrep. . . &domain=pdf figure . identification of two main subtypes of renal oncocytoma (a) copy-number variations in renal oncocytomas in comparison to eosinophilic chrcc (eosinophilic chrcc sequencing data were downloaded from the tcga cghub repository [https://cghub.ucsc.edu/]) (davis et al., ). blue corresponds to loss of one copy, red corresponds to a gain, and gray on chromosome y indicates a female. (b) somatic mutations in renal oncocytomas in comparison to chrcc (chrcc sequencing data were downloaded from the tcga cghub repository [https:// cghub.ucsc.edu/]) (davis et al., ). only snvs common between oncocytoma and chrcc are shown; the complete list of detected somatic snvs and indels is reported in tables s and s . (c) expression levels of key genes from the transcriptome analysis. each bar represents log -transformed transcript abundance. error bars show ses. (d) principal component analysis (pca) of gene expression identifies two subtypes of oncocytoma. the first principal component (pc ) separates tumor and normal samples; the second principal component (pc ) separates oncocytomas into two subtypes. (legend continued on next page) cell reports , – , december , ª the authors https://cghub.ucsc.edu/ https://cghub.ucsc.edu/ https://cghub.ucsc.edu/ carcinomas to more benign oncocytomas, defects in mitochon- drial removal may underlie the oncocytoma phenotype and pro- duce benign instead of malignant disease (guo et al., a; karsli-uzunbas et al., ; strohecker et al., ). this also suggests that autophagy and mitochondrial quality control are important for promoting tumorigenesis (guo et al., b). to address the cause and role of oncocytomas in the spec- trum of cancer, we sequenced the exome and transcriptome of the most common oncocytoma, those that arise in the kidney (linehan and ricketts, ). we identified two major subtypes, one without (type ) and the other with (type ) recurrent whole- chromosome losses that contain few other mutations. both subtypes had recurrent inactivating mutations in nuclear- and mitochondria-encoded proteins critical for respiration and dis- played activation of ampk and p . recurrent ccnd chromo- somal rearrangement and overexpression was a likely cancer driver mutation in type . both subtypes had evidence of defec- tive autophagy attributed to metabolic-deficiency-induced golgi disassembly and lysosome dysfunction that blocked lamp- trafficking and lysosomal protease activation. pharmacologic inhibition of mitochondrial complex i with metformin to repli- cate mitochondrial dysfunction in oncocytomas caused ampk activation and golgi disassembly and blocked lamp- traf- ficking and autophagy. thus, mitochondrial respiration defects that arise early in renal tumorigenesis trigger a metabolic check- point, trafficking and lysosome defects, and failure of mitochon- drial quality control, activating p and ampk as a barrier to tumor progression. moreover, the similarities in the mutational landscape and transcriptome suggest that type oncocytoma and eosinophilic subtype of chromophobe renal cell carcinoma (chrcc) are closely related, with chrcc having acquired addi- tional driver mutations in p and pten and further genetic instability. thus, treatment of type oncocytomas requires more consideration. genomic analysis indicates two main subtypes of renal oncocytoma whole-exome sequencing of renal oncocytomas and matched adjacent normal tissue and rna sequencing of of these pairs were performed. copy-number variation (cnv) analysis from exome sequencing indicates that tumors are clonal, with two distinct subtypes based on the pattern of aneuploidy. one tumor was an outlier that was excluded from further analysis. type is diploid and type is hypodiploid with loss of chromosome , x or y, and/or and (figures a and s a; table s a). type shows no sex bias, but type has male predominance (five male/one female), suggesting strong selection for loss of the y chromosome. the one type tumor arising in a female has lost one x chromosome (figure a). strong selection for loss of y in males or x in females suggests possible involvement of gene loss on the pseudoautosomal region (par). few and no recurrent single-nucleotide variants (snvs) ( nonsynonymous snvs in tumors; tables s b and s ) or in- (e) type and type oncocytomas have distinct histology, with type having a la (f) gene expression similarities between oncocytoma and chrcc. pca of gene identify the three rcc subtypes as separate clusters with the corresponding ma demonstrating similarities in gene expression patterns. cell re sertions/deletions were detected (table s ). there were no mu- tations in common cancer-causing genes (p , pten) with the exception of one tumor with an mll mutation (figure b). three tumors have mutations in nuclear-encoded mitochondrial genes ndufv , uqcrc (type ), and slc a (ant ) (type ). ant is located on the x chromosome, and this ant mutant tumor likely has a loss-of-function mutation as it has a frameshift muta- tion with x chromosome loss (figure b; table s ). mutations in flcn, vhl, fh, sdhb, sdhc, or sdhd, known drivers in other renal cell carcinomas (rccs), were not detected. despite loss of chromosome in type , expression levels of fh, sdhb, and sdhc located on chromosome were not affected (figure c). the nuclear genome mutation spectrum observed in onco- cytomas was c > a ( ), c > g ( ), c > t ( ), t > a ( ), t > c ( ), and t > g ( ). the analysis showed transition to transversion ratio (ts/tv) of . in somatic mutations in contrast to . for germline mutations (found in dbsnp) consistent with expected values (ebersberger et al., ). the comparison displayed strong enrichment for transversion mutations among somatic mutations, suggesting reactive oxygen species (ros) exposure at some point in oncocytoma evolution. oncocytomas have mitochondrial genome mutations respon- sible for respiration defects (gasparre et al., ; mayr et al., ; simonnet et al., ), with all oncocytomas examined here having mutations, and mutations in mt-cox , mt-cox , mt-cox , mt-nd , mt-nd , and mt-cytb found in three or more tumors (figures b and s b; table s ). thus, the distin- guishing feature of both subtypes of renal oncocytoma is recur- rent inactivating mutations in mitochondrial genes encoded by both the nuclear or mitochondrial genomes. the mitochondrial point mutation spectrum for oncocytomas was c > t ( ) and a > g ( ) on the heavy strand and c > t ( ) and a > g ( ) on the light strand. the only other point muta- tions detected were c > a ( ) on the light strand. the dominance and strand bias of c > t and a > g mutations on the heavy strand are consistent with findings from other human cancers and postulated to result from mitochondrial dna replication errors (ju et al., ). in contrast, the c > a mutations are consistent with damage by ros (thilly, ), which were elevated ( %) compared to other cancers ( %), (ju et al., ). while the majority of oncocytoma mitochondrial mutations showed the signature of dna replication error indicating that dna replication errors are the dominant source of mutations, most of the patho- genic mutations with high allelic frequencies (> %) are indels and occure in the complex i subunits. in summary, out of on- cocytomas have a pathogenic mitochondrial dna mutation fre- quency greater than % (table s ). the gene expression pattern also represents type and oncocytomas as distinct groups and indicates that the matched normal adjacent tissue (nat) from sample is likely contami- nated with tumor (figures s c and s d, a). principle component analysis (pca) shows type and grouping separately with type forming a tighter cluster showing greater similarity (figure d). rger volume of eosinophilic cytoplasm relative to the nucleus. error bar, mm. expression for oncocytoma, chrcc, clear cell rcc, and papillary cell rcc tched normal samples forming one cluster. oncocytomas cluster with chrcc ports , – , december , ª the authors figure . chromosome rearrangements and overexpression of ccnd in type and p activation in type and oncocytomas (a) overexpression of a single allele of ccnd . the rna-sequencing coverage tracks for four tumors (t , t , t , and t ) and matched normal samples (n , n , n , and n ) are shown in gray. the numbers in brackets display the coverage for this region and reflect the level of the gene expression, showing that ccnd is over -fold higher in tumors. snps present in the exons of ccnd are shown as colored bars. some of the snps are heterozygous and are indicated by the two- color bars showing the relative expression of the two alleles. the appearance of homozygous snps in tumor where the same snps appear heterozygous in the matched normal sample, as in t versus n , is a result of the overexpression of a single allele of ccnd . (b) western blot showing elevated ccnd protein expression in tumors. the asterisks marks sample , which has normal (n) tissue mixed with oncocytoma (o) tissue. multiple bands represent different phosphorylated forms of ccnd . (c) representative fluorescence images of ccnd fish show rearrangement in type (sample ), but not type (sample ), tumors. white arrowheads show segregation of ccnd probe. (d) karyotype of renal oncocytomas shows chromosomal rearrangement including translocations, inversions, and deletions near ccnd in type and loss of chromosome and y in type . (e) summary of genetic alterations in all oncocytoma samples. (legend continued on next page) cell reports , – , december , ª the authors the separate groups persist using only gene expression from diploid chromosomes from types and (figure s d, b and c). both types are distinct from normal controls (figures d and s c). type and are distinguished histologically, with type having a more expansive eosinophilic cytoplasm (figures e and s ), suggesting greater accumulation of defective mito- chondria, thought to be a main contributing factor to the histo- logical appearance of these tumors. type oncocytoma may be the precursor of eosinophilic chrcc the relationship between oncocytomas and other renal tumors is not currently known. thus, we compared the genomic and transcriptomic signature of oncocytomas with rcc subtypes. the pattern of gene expression in oncocytoma was clearly distinct from clear cell and papillary cell rcc (figure f), consis- tent with the vastly different mutational landscape of these tumors (gao et al., ; varela et al., ). in contrast, chrcc has some histologic similarities and common biomarkers with oncocytoma, and distinguishing these tumor types is important, as chrcc is a more aggressive disease with higher risk of metastasis (ng et al., ). there are two types of chrcc, classic and eosinophilic, with the eosinophilic subtype possessing some similarities with onco- cytoma (davis et al., ). the global gene expression pattern of both oncocytoma and chrcc are similar (figure f), and both have a gene expression signature of distal tubule, suggest- ing that they originate from a common cell type (figure s e). eosinophilic chrcc has two subgroups: one is chromosomally diploid like type but without rearrangement or overexpression of ccnd , and the other has a pattern of chromosome loss similar to type with loss of chromosomes , x, or y, but with further losses including , , , , and (figures a and b) (davis et al., ). like type , eosinophilic chrcc also has a sex bias ( male/ female) whereas classic chrcc has no gender bias ( male/ female) (figure a; table s ). the main nuclear genomic difference between oncocytomas and chrcc are mutations in p and pten in chrcc (figure b). tert promoter mutations and upregulation of telomerase reverse transcriptase (tert) expression occur in % of chrcc (davis et al., ), and both oncocytoma subtypes lacked tert expression (figure c), indicating the absence of this driver mutation. the similarities in gene expression, aneuploidy pattern, and histology suggest type may be closely related to eosinophilic chrcc. one possibility is that chrcc may have acquired additional mutations in tp , pten, or tert, leading to further genomic instability and a less indolent natural history. alternatively, there could be a single cell type precursor for both type oncocytoma and chrcc, where chromosome is lost followed by either pathogenic mitochondrial genome or p mutations, directing fate to either oncocytoma or chrcc. this, however, does not account for the common mitochondrial (f) oncocytomas have a gene expression signature similar to chrcc without p gene expression values. the correlation is calculated for the set of genes (table mutation in p . (g) western blot for p showing induction in oncocytomas with quantitation rel cell re mutations in type and oncocytoma without chromosome loss in type . in contrast to the increased nuclear genomic mutation burden in chrcc compared to oncocytoma, there was less mutational burden of the mitochondrial genome in chrcc compared to on- cocytoma (p < . ) (figure b) (davis et al., ). hetero- plasmy may be a prerequisite to selection for a less defective pool of mitochondria during progression of benign type to a more malignant chrcc. recurrent ccnd rearrangement and amplification in type oncocytomas four of the five type oncocytomas had high expression of ccnd in comparison to type and nat (figure c). ccnd encodes the cell-cycle regulator and oncoprotein cyclind . all three tumors exhibit monoallelic expression of ccnd consis- tent with chromosomal rearrangement that led to aberrant high expression of one ccnd allele (figure a) consistent with pre- vious observations (sukov et al., ). western blot shows high cyclind protein expression in some tumors with high mrna expression (figure b). cyclind expression is also elevated in some of the type tumors, reflecting non-transcriptional mech- anisms for cyclind activation (figure b). fluorescence in situ hybridization (fish) analysis of three each of type and oncocytomas confirmed translocation of q at the ccnd locus in type and not in type (figure c). cyto- genetic analysis of additional renal oncocytomas showed eight tumors with translocations, inversions, or deletions near ccnd ( q ) but an otherwise chromosomally intact genome (figure d). these findings are consistent with the presence of two mutually exclusive categories of oncocytoma: type with ccnd rearrangement and no other gross chromosomal losses, and type with chromosome loss. of the oncocytomas, two were chromosomally stable, harboring a translocation between chromosomes and of unknown significance (figure d) (hudacko et al., ). five others had unique chromosome re- arrangements and cnvs, suggesting low-level diversity of this tumor type (figures d and e). the expanded characterization of oncocytomas confirmed the association of type with ccnd rearrangements ( / ) and type with chromosome loss ( / ), sex chromosome loss ( / ), and male bias ( / male, / female) (figure e). no aberrant high expres- sion of ccnd was detected in chromosomally stable chrcc (six tumors) so there is no evidence that type progresses to a subset of chrcc that also lacks chromosomal losses. since translocation or rearrangement of ccnd and overexpression of cyclind is a well-known oncogenic driver, it is likely a driver mutation in type oncocytomas. p is a barrier to oncocytoma progression p is mutated in out of ( %) chrcc tumors (davis et al., ) and not in oncocytoma (figure b). we found a set of mutation as shown by correlation heat map between oncocytoma and chrcc s ), which are differentially expressed between chrccs with and without a ative to actin. ports , – , december , ª the authors figure . oncocytomas show a gene expression signature of oxidative metabolism and mitochondrial and energetic defects (a) oncocytomas have increased mitochondrial dna copy number. p value was calculated for a one-tailed t test. (b–d) canonical pathway analysis. each graph represents the top canonical pathways enriched for the corresponding gene set (http://www.ingenuity.com/). numbers on top of the bars indicate the number of genes in the pathway. differential expression analysis of type versus type identifies genes with fdr-corrected p value < . . (b) pathway analysis of a set of , genes differentially expressed between tumor and normal samples. the set of genes was selected based on the fdr-corrected p value < . . red corresponds to genes that are upregulated in oncocytomas, and green corresponds to genes downregulated in oncocytomas. (c) pathway analysis of a set of genes that are upregulated in oncocytomas compared to normal samples. the set of genes was selected based on the fdr-corrected p value < . . red arrowhead marks ampk signaling. (d) pathway analysis of a set of genes differentially expressed between type and type oncocytoma. the set of genes was selected based on the lowest p values. red corresponds to genes upregulated in type . red arrowheads mark ampk and p signaling. (legend continued on next page) cell reports , – , december , ª the authors http://www.ingenuity.com/ genes differentially expressed between chrcc with and without p mutation (table s ) and oncocytomas have the gene signa- ture more similar to chrcc without p mutation (figure f). this finding is consistent with changes in gene expression linked to p mutational status in both chrcc and oncocytomas. p protein is stabilized as a barrier to tumorigenesis by stress, oncogene activation including ccnd amplification, and genome damage. to test if p was activated in benign on- cocytomas explaining its mutation upon progression to chrcc in type , we examined p levels. in comparison to nat, wild- type p protein was induced in most oncocytomas indepen- dent of subtype, suggesting that p activation in oncocytomas may contribute to their slow growth and benign characteristics (figure g). type and oncocytomas display mitochondrial defects and metabolic stress since metabolic stress, triggered by mitochondrial defects, is a potential cause of p activation in oncocytomas, we assessed mitochondrial genome copy number, gene expression signa- ture, mitochondrial complex protein expression, and metabolic signaling. both type and have elevated mitochondrial genome copy number relative to nat, with type being greater, suggesting increased mitochondrial accumulation (figure a; table s ). pathway analysis of the transcriptome indicated that in com- parison to nat, oncocytomas have a predominance of downre- gulated genes that are represented in metabolic and degradative pathways (figure b; tables s and s ). mitochondrial accumu- lation in oncocytomas may be due to compensatory increased biogenesis or decreased clearance by autophagy, concepts that are not mutually exclusive. indeed, ppargc a expression is induced several fold in oncocytomas compared with nat (table s ), indicating activation of mitochondrial biogenesis. pathway analysis of genes upregulated in oncocytomas identi- fied ampk, creatine-phosphate biosynthesis, and ketolysis pathways suggestive of energy crisis (figure c; table s ). on- cocytomas have high expression of genes encoding the tca cy- cle and other mitochondria-expressed gene products involved in respiration (figure c; table s ). comparison of differential gene expression between types and identified metabolic and cancer pathways such as ampk and p (figure d; tables s and s ). both type and type oncocytomas have ampk pathway upregulated compared to nat, with upregulation more pronounced in type . type has . -, . -, . -, and -fold higher levels of prkab , prkag , acaca (acc ), and acacb (acc ), whereas type has -, . -, and . -fold higher levels of prkag , acaca, and acacb, respectively. the mitochon- drial accumulation and genome mutations, oxidative meta- bolism gene expression signature, and patterns of chromosome loss suggest similarities between oncocytomas and eosinophilic (e) oncocytomas show upregulation of a gene expression signature for mitochon encoded genes as for chrcc (davis et al., ) for ease of comparison. ye mutations. star indicates somatic mutations in nuclear-encoded genes. (f) deregulation of mitochondrial protein expression in oncocytomas determined (g) oncocytomas have loss of mtor as indicated by reduction of p-s (ser (a-subunit, thr ) in western blots. cell re chrcc (figure e) (davis et al., ). this may reflect an increased number of mitochondria and not necessarily increased mitochondrial metabolism. increased mitochondrial genome copy number was reflected in high cytochrome c levels in oncocytomas relative to nat in all tumors with the exception of sample , where normal tissue was contaminated with tumor (figure f). mitochondrial genome mutations resulting in defects in complex i of the electron trans- port chain (etc) are common in oncocytomas (figures b and s b) (gasparre et al., ; mayr et al., ; simonnet et al., ). low or undetectable levels of the subunit ndufs (com- plex i), uqcrc (complex iii), and mt-cox (complex iv) were observed in a subset of oncocytomas indicative of impairment in mitochondrial respiration at multiple points in the etc (figure f). compared to nat, ant , and slc a (ant ), protein expres- sion levels were low or undetectable in type in contrast to the increased mitochondrial mass (figure f). ant is on the par and had a reduced mrna expression (log fold change = � . , uncorrected p = . ) associated with loss of the y or x chromosome and correspondingly reduced protein expression (figure f). tumor had no detectable ant , likely due to a frameshift mutation and x chromosome loss containing the other allele (figures b and f). interestingly, mutations in ant also occur in chrcc (figure b). ant and ant modulate the mitochondrial permeability transition pore, and their deficiency impairs mitochondrial function (kokoszka et al., ). these findings are consistent with unifying defects in mitochondrial function in oncocytomas. to examine the potential manifestation of mitochondrial metabolic defects on oncocytoma, we assessed the activity of the nutrient sensor and master regulator of cell growth, the mammalian target of rapamycin (mtor), and the metabolic stress response regulator ampk. both subtypes had reduced phospho(p)-s , indicating loss of mtor activity, and increased phospho(p)-ampk (thr ) (figures g and s f), indicating activation of ampk signaling, consistent with upregulation of the gene expression signature (figure c, arrow). these findings reflect metabolic and growth impairment consistent with defec- tive mitochondrial function in oncocytomas. oncocytomas manifest phenotypes of defective autophagy to test if autophagy defects underlie the accumulation of defec- tive mitochondria in oncocytomas, we examined the levels of autophagy substrates that accumulate with autophagy inactiva- tion. oncocytomas show accumulation of mitochondria that are normally degraded by autophagy as determined by immuno- histochemistry (ihc) and western blotting for the mitochon- drial proteins tom and cytochrome c (figures a and b). levels of the essential autophagy regulator beclin were reduced (figures b and s ), and puncta of lc indicative of drial respiration. red and blue correspond to up- or downregulation of nuclear- llow and gray correspond to mitochondrial genes with and without somatic by western blots. the asterisk marks sample with mixed normal and tumor. / ) and induction of ampk signaling as indicated by induction of p-ampk ports , – , december , ª the authors figure . oncocytomas lack autophagosomes, accumulate autophagy substrates and dysfunctional mitochondria, and are primed for mitophagy (a) human oncocytomas accumulate mitochondria (tom ) and p (autophagy substrate) and lack lc puncta (autophagosomes) indicative of autophagy inactivation. representative ihc for each of the two subtypes with all in figure s . (b) western blots of indicated mitochondrial and autophagy proteins in normal tissues and oncocytomas. quantitation of lc -i/ii and p levels is shown below. (c) oncocytomas have evidence for activation of the fission and the pink /parkin machinery. western blots of normal and oncocytoma tissues for indicated proteins. fl, full length; dmts, without mitochondrial translocation sequence. (legend continued on next page) cell reports , – , december , ª the authors autophagosomes were present in nat and absent in oncocyto- mas (figure a). consistent with the absence of lc puncta and autophagy, oncocytomas had higher levels of the unprocessed form of lc (lc -i) and lower levels of the processed, autopha- gosome-associated form of lc (lc -ii) than nat as indicated by western blotting and lc i/ii ratios (figure b). the absence of lc -ii and autophagosomes and the accumulation of lc -i is a characteristic of genetic ablation of an essential auto- phagy gene in mice (karsli-uzunbas et al., ). oncocytomas also displayed high levels of the autophagy substrate p that accumulates in autophagy-defective cells and tissues (figures a and b). mitophagy is primed, but not executed, in oncocytomas since oncocytomas accumulate defective mitochondria, we examined oncocytomas for evidence of mitophagy dysfunc- tion. mitochondria undergo fission in response to stress to allow their segregation and elimination by mitophagy. fission is induced when the protease oma cleaves the dynamin- related gtpase opa (mcbride and soubannier, ). mi- tophagy is subsequently activated by loss of mitochondrial membrane potential that prevents cleavage and inactivation of the kinase pten-induced putative kinase (pink ), which recruits the e ligase parkin to mitochondria (youle and narendra, ). parkin then adds ubiquitin chains to mitochondrial outer membrane proteins to signal recruitment of autophagy adaptors such as p , which interact with lc -ii in autophagosome membranes, allowing their engulf- ment within autophagosomes. in normal conditions, oma is cleaved and opa is not, allow- ing fusion and preventing fission and mitophagy. this was the case in nat, where cleaved oma ( kda) and less cleaved opa (s-form) were apparent (figure c). in contrast, oncocyto- mas have uncleaved oma ( kda) and accumulation of cleaved opa (s-form) consistent with activation of fission. since lc -ii-positive autophagosomes were not detected in oncocytomas (figures a and b), this suggests that the initial steps of mitochondrial fission are initiated but the process of autophagosome sequestration is not. oncocytomas have un- cleaved pink (fl-pink ) and accumulation of parkin, consis- tent with priming of mitophagy without autophagosome forma- tion (figure c). pink is cleaved by parl and further cleaved to the p kda fragment to inactivate fission and mitophagy when mitochondria are healthy. importantly, normal tissue but not oncocytomas have the p kda cleaved pink , consistent with inactivation of pink and priming of mitophagy (figure c). interestingly, cells with pathogenic mitochondrial dna mutations are defective for mitochondrial membrane fusion (mishra et al., ), consistent with activation of the fission machinery and the pink /parkin system shown here in oncocytomas (fig- ure c). thus, upstream signaling of mitophagy at mitochondria (d) primary cultures of oncocytoma cells display autophagy substrate accumu oncocytoma cells (o /o ) accumulate lc and p aggregates, mitochond (e) primary cultures of oncocytoma cells ( /o ) show accumulation of dys icantly lower relative membrane potential than normal cell controls nk and n (f) primary oncocytoma cells (o ) have reduced ocr and increased ecar wh (n ). cell re occurs in oncocytomas, but sequestration is absent, suggesting a block in autophagy. impaired mitochondrial respiration in primary oncocytoma cells attempts to generate cell lines from renal oncocytomas by others and us have been unsuccessful. to address mitochon- drial function, two pairs of normal adjacent kidney (nk / n ) and oncocytoma-derived (o /o ) primary cell cul- tures were examined. primary oncocytoma cells remain viable in short-term culture (< week) without undergoing cell division, permitting limited analysis. in contrast to nk and n , o and o primary cultures were composed of large cells with lc and p aggregates and increased mitochondria, glycogen, and lipids indicative of defective autophagy (figure d). even though primary oncocytoma cells had severalfold greater mito- chondrial mass, relative mitochondrial membrane potential was significantly lower when compared to normal cells, consis- tent with etc defects (figure e). one of the primary cultures (o ) provided sufficient material for determination of the oxy- gen consumption rate (ocr) and extracellular acidification rate (ecar). compared to normal cells, o cells were defective for respiration and more glycolytic, consistent with pathogenic mitochondrial genome mutations (figures f and s b). oncocytomas display lamp- trafficking, golgi, and lysosome defects autophagy delivers cargo to lysosomes for degradation, and interference with lysosome function and cargo degradation feeds back to inhibit autophagy (tanaka et al., ). moreover, muta- tionsinthemajorandessential lysosome transmembranecompo- nent lysosome-associated membrane protein- (lamp- ) cause lysosomal storage disease and interfere with autophagy (eskeli- nen, ). to test if lysosome defects in oncocytomas interfere with autophagy, lysosome numbers and localization were exam- ined by monitoring lamp- . lamp- -positive vesicle distribution in types and was distinct from nat (figure a). in contrast, and suggestive of lysosome abnormality, localization of lamp- -positive vesicles was perinuclear in type and peripheral in type (figure a). lamp- is synthesized and heavily polylactosamine glycosy- lated in the golgi apparatus prior to transit to lysosomes, which serves to protect the protein from proteolysis in the lysosome lumen where most of the polypeptide resides. oncocytomas have enhanced glycosylation of lamp- compared to nat as indicated by its higher molecular weight (figure b). increased glycosylation of lamp- occurs when it is retained in the golgi, where this post-translational modification takes place (nabi and rodriguez-boulan, ). in contrast to perinuclear stacks of golgi in nat, oncocytomas displayed disrupted golgi organiza- tion with lamp- co-localization (figures a and c), consistent lation. in contrast to primary cells derived from nat (nk /n ), primary ria, glycogen, and lipids, characteristics of autophagy impairment. functional mitochondria with several fold more mitochondrial mass but signif- . en provided a fermentable carbon source in comparison to normal control cells ports , – , december , ª the authors figure . golgi disassembly, altered lamp- , and defective cathepsin activation in oncocytomas (a) golgi disassembly and altered lamp- localization in human oncocyto- mas. representative ihc for each subtype with all shown in figure s . (b) western blots showing enhanced lamp- glycosylation (increased molecular weight) in human oncocytomas. oncocytomas have defective cts-b and -l activation. low molecular weight, cleaved, activated forms of cathepsins predominate in normal tissue. pro, proenzyme; int, intermediate. (c) golgi disassembly and lamp- co-localization in human oncocy- tomas. representative fluorescence images of each subtype stained for golgi (gm ), lamp- , and nuclei (dapi). the fluorescence images of all are shown in figure s . cell reports , – , december , ª the aut with golgi disassembly and lamp- retention and enhanced glycosylation (figures b and c). the major lysosomal proteases, cathepsins (ctss), are also processed in the golgi and cleaved and activated to mature forms upon reaching the acidic environment of lysosomes (ishi- doh and kominami, ). in contrast to nat, most oncocyto- mas had predominantly inactive cts-b and -l and lacked the cleaved, active forms, indicative of defective trafficking and lyso- some function (figure b). cts-b and -l are cysteine proteases involved in lysosomal protein turnover, and failure to activate them is consistent with the accumulation of autophagic sub- strates in oncocytomas. these findings suggested that mito- chondrial defects and energy crisis in oncocytomas produce a general disruption of golgi-lysosome protein trafficking that impairs autophagy. the golgi is a highly structurally organized organelle essential for protein sorting, trafficking, and post-translational modifica- tion. the golgi undergoes disassembly at mitosis for proper par- titioning in daughter cells and in response to metabolic stress to conserve energy (mao et al., ). to test if metabolic stress triggers golgi disassembly and enhances lamp- glycosylation that is alleviated by autophagy, isogenic tumor cells wild-type or null for the essential autophagy gene atg (guo et al., a) were starved and golgi and lamp- localization and glycosyla- tion were examined. wild-type cells displayed no changes in lamp- glycosylation but had increased p-ampk, inhibition of p-s , perinuclear golgi with distinct lamp- localization, and only modest golgi disruption with prolonged starvation (figures a and b). autophagy-deficient atg null cells, however, showed golgi disruption and enhanced lamp- glycosylation even under normal growth conditions, which was increased by starvation (figures a and b). lamp- co-localized with the golgi in the starved atg -deficient cells, consistent with golgi retention (figure b). thus, metabolic crisis induced by either starvation or autophagy deficiency disrupts the golgi and alters lamp- glycosylation. complex i inhibition and golgi disassembly block autophagy metabolic stress and ampk activation triggers golgi disas- sembly by phosphorylation of golgi-specific brefeldin a resis- tance factor (gbf ), a guanine nucleotide exchange factor (gef) for arf-gtpases. phosphorylation of gbf disassociates gbf from the golgi membrane, producing golgi fragmentation (miyamoto et al., ). to test the hypothesis that mitochon- drial mutations impairing complex i in oncocytomas produce metabolic crisis that disrupts golgi function, thereby inhibiting autophagy, we examined the cellular response to the complex i inhibitor metformin (bridges et al., ). metformin potently induced ampk activation (increased p-ampk), inhibited mtor (reduced p-s ), disrupted the golgi, produced golgi-lamp- co-localization, and enhanced lamp- glycosylation (figure c). importantly, metformin reduced autophagic flux as measured by inhibition of lc -i to -ii processing and lc puncta in the pres- ence of ba (figure d). the other complex i inhibitors phenfor- min and rotenone acted similarly (figure e). treatment with the ampk activator aicar confirmed that these changes are ampk mediated (figure e). pharmacological disruption of the golgi hors figure . sustained metabolic stress induces ampk signaling, golgi disassembly, golgi-lamp- co-localization, and lamp- hyper- glycosylation and inhibits autophagy flux (a) autophagy deficiency and starvation increase lamp- glycosylation. western blots of autophagy-competent and autophagy-deficient tdcls following , , and hr of starvation (hbss) for the indicated proteins. starvation induces ampk signaling (increased p-ampk) and reduces mtor activity (decreased p-s ). (b) autophagy deficiency and starvation cause golgi disassembly and lamp- co-localization. representative fluorescence images of autophagy-competent and autophagy-deficient tdcls stained for golgi (gm ), lamp- , and dna (nuclear dapi). (c) metformin (met) disrupts golgi and causes lamp- co-localization. autophagy-competent tdcls stained for golgi (gm ), lamp- , and nuclei (dapi) following metformin treatment for the indicated times. white arrowheads show golgi-lamp co-localization. bottom panel: western blots from samples. (d) metformin disrupts autophagic flux. western blots of metformin-treated wild-type tdcls for lc showing less lc -ii in ba . metformin disrupts autophagic flux indicated by reduced puncta of endogenous lc with ba with quantitation. (e) phenformin (phen), rotenone (rot), -aminoimidazole -carboxamide ribonucleotide (aicar), and brefeldin a (bref a) disrupt golgi and cause golgi-lamp- co-localization and lamp- hyper-glycosylation. autophagy-competent tdcls stained for golgi (gm ) and lamp- following phen, rot, aicar or bref a treatment for indicated times. nuclei (dapi). bottom panel: corresponding western blots. cell reports , – , december , ª the authors figure . model for oncocytoma genesis chronic mitochondrial metabolic defect causes mitochondrial accumulation. with brefeldin a induced golgi-lamp co-localization and lamp- hyper-glycosylation (figure e). thus, mutational inac- tivation of the mitochondrial etc in oncocytomas is likely the cause of ampk activation and disruption of golgi, autophagy, and lysosome function. discussion molecular characterization of benign renal oncocytomas re- vealed two main subtypes that share recurrent inactivating mutations in mitochondrial genes encoded by both nuclear and mitochondrial genomes. clonal expansion of somatic mito- chondrial mutations in oncocytomas suggests that they are an early event (gasparre et al., ). this might indicate a causal role for mitochondrial defects in tumor promotion as previously suggested (gasparre et al., ). the genomic analysis of renal oncocytomas performed here was not able to resolve this issue; however, alterations of the nuclear genome consistent with oncogene activation and tumor suppressor gene inactiva- tion were found in almost all cases. several issues we were able to address were the relationship between oncocytomas and other renal tumors, the cause of the metabolic defects, and the reasons for mitochondrial accumula- tion. diploid type has chromosomal rearrangements and upre- gulation of ccnd , a known oncogene. while type lacked a clear driver mutation, it was hypodiploid, which could be the underlying basis for tumor formation, with the consistent loss of chromosome being the prime candidate for location of a tu- mor suppressor gene. loss of x or y also suggests the presence of a tumor suppressor on the par that escapes x inactiva- tion. despite differences at the genomic level, the two subtypes were qualitatively similar in phenotype. our data suggest that oncocytomas have activated p , and type may progress to more malignant eosinophilic chrcc upon acquiring p , pten, and other mutations. recent sequencing findings also support similarities between renal oncocytomas and chrcc and the absence of p mutations cell reports , – , december , ª the authors in oncocytomas (durinck et al., ). autophagy deficiency in genetically engi- neered mouse models causes energy crisis, activates p , and suppresses tumor growth, effects lessened by p deficiency (guo et al., b). analo- gously, oncocytomas may represent benign disease whose growth is limited by metabolic crisis and activation of p . subsequent mutation in p in type may restore growth capacity and pro- gression to eosinophilic chrcc (guo et al., a; strohecker et al., ). it is also worth noting that chrccs have significantly fewer mitochondrial muta- tions than oncocytomas, suggesting that progression from onco- cytoma might be aided by heteroplasmy and the ability to partly recover the functional pool of mitochondria (ju et al., ). this might be achieved by restoration of autophagy and lyso- somal biogenesis by tfe or tfeb activation (linehan and rick- etts, ). alternatively, tumor cells depleted of mitochondrial dna recover respiration, etc function, and tumor growth by horizontal transfer of normal mitochondria from non-tumor to tumor tissue (tan et al., ). these findings point to the need for tumors to preserve mitochondrial etc function. in contrast, type may represent an evolutionary dead end, as these tumors with ccnd rearrangements are less susceptible to recurrence (sukov et al., ). recurrent pathogenic mitochondrial gene mutations en- coded within the mitochondrial and nuclear genomes are the likely cause of the respiration defects in oncocytomas, consis- tent with and expanding on previous work. inactivating muta- tions are found in complex i, iii, iv, and control regions, in nuclear encoded ndufa , and now also in complex v, ant , ndufv , and uqcrc . alterations in key mitochon- drial components are associated with the accumulation of defective mitochondria, suggesting a link between chronic metabolic impairment and autophagy suppression. indeed, depletion of mitochondrial dna and the resulting respiration defect inactivates autophagy in budding yeast and mamma- lian cells (graef and nunnari, ; tan et al., ). in agree- ment with these findings, the pathogenic mitochondrial muta- tions and respiration defects in the oncocytomas reported here similarly suppress autophagy with the resulting metabolic insufficiency attributed to disruption of golgi and lysosome function (figure ). a major consequence of compromised mitochondrial respi- ration in oncocytomas is chronic metabolic deficiency exem- plified by ampk activation and loss of mtor signaling. this is also seen in genetically engineered mouse models for cancer with autophagy inactivation (guo et al., b; karsli- uzunbas et al., ) and in response to pharmacologic inhibition of complex i (e.g., metformin) in cancer cells in vitro. normally, transient energy crisis and ampk activation cause golgi disassembly to block trafficking and secretion that is thought to conserve energy. in contrast, the dysfunctional mitochondria in oncocytomas causes a chronic metabolic defect, sustained energy crisis, ampk activation, and disrup- tion of golgi and lysosome function essential for autophagic cargo degradation (figure ). importantly, inhibition of com- plex i is sufficient to disrupt the golgi, trafficking, and auto- phagic flux. thus, cancer cells need to sustain mitochondrial respiration to prevent metabolic crisis that inhibits trafficking. it is worth noting that pten and p mutations, which alleviate ampk activation, occur in chrcc and may facilitate progres- sion of type tumors by restoring golgi, autophagy, and lyso- some function. oncocytic features are common to many different subsets of renal tumors such as those with sdhb, sdhc, sdhd, and flcn mutations and in hybrid chrcc tumors (linehan and rick- etts, ). this may be due to the occurrence of numerous means to impair mitochondrial respiration, producing chronic metabolic and trafficking defects, and the resulting mitochon- drial accumulation as described here in oncocytomas. metfor- min and other means to inhibit mitochondrial function have anti-cancer activity (pollak, ; viale et al., ; weinberg et al., ). our findings suggest that this may be due in part to chronic metabolic stress-induced trafficking defects, necessi- tating the preservation of etc function to overcome a metabolic barrier to tumorigenesis. experimental procedures tumor samples tumor and adjacent normal kidney tissues from ten sporadic oncocytomas at mskcc were collected. all patients had previously consented to a tissue protocol. this study was preapproved by the institutional review board (irb), and all patients signed informed consent. all samples were reviewed by a dedi- cated uropathologist. paired fresh-frozen normal and primary tumor tissue blocks were identified, marked, and macrodissected for maximal tumor den- sity. the two tumor specimens with normal adjacent tissue from cinj were obtained from a de-identified tissue bank maintained at the biospecimen repository service under the auspices of an irb-approved protocol. all spec- imens were pre-existing and de-identified. tissues for cytogenetics were obtained by reviewing records to identify all cases of renal oncocytomas and chrcc for which cytogenetics was performed at robert wood johnson university hospital in the past years. whole-exome and rna-sequencing data analysis the agilent sureselect human all exon v enrichment protocol was used for exome capture. the exome was sequenced on illumina hiseq , bp paired-end reads to a minimum depth of million reads per sample. the reads were preprocessed with picard to remove pcr duplicates and aligned to the human reference genome (hg ) with bowtie . somatic point mutations and small indels were called with mutect and gatk somatic indel detector algorithms. cnvs were detected with exomecnv. library prepara- tion and rna sequencing were carried out using the illumina truseq rna sample prep kit v , according to the manufacturer’s protocol (illumina), and samples were sequenced on the illumina hiseq ( bp paired- end reads) to a minimum depth of million reads per sample. sequence reads were mapped using tophat /bowtie algorithm. analysis of gene expression was performed using cufflinks and deseq. the complete descrip- tion of the sequencing and genomic analysis and all other methods can be found in supplemental experimental procedures. cell re accession numbers the accession number for the sequencing data reported in this paper is sra: srp . supplemental information supplemental information includes supplemental experimental procedures, two figures, and twelve tables and can be found with this article online at http://dx.doi.org/ . /j.celrep. . . . author contributions s.j. designed and performed the histology and biological experiments. d.t. performed sequencing data analysis. h.a. performed karyotype analysis. a.a.h. and j.j.h. guided the renal tumor biology and tumor procurement. m.y. helped perform fish analysis. s.g. helped conceive and direct the proj- ect and human tissue and chromosome analysis. c.s.c. directed project and bioinformatics analysis. e.w. conceived and directed the project. acknowledgments e.w. acknowledges support from the nih (grants r ca , r ca , and ca ), the val skinner foundation, and cinj (grant p ca ). c.s.c. and d.t. acknowledge support from cinj. s.g. ac- knowledges support from the triple negative breast cancer foundation, the hugs for brady foundation, and the nih (grants r ca and r ca ). s.j. received support from a postdoctoral fellowship from the new jersey commission for cancer research (dfhs ppco ). this work used the functional genomics/rutgers university cell and dna repository, biospecimen repository service, and flow cytometry/cell sorting cinj core facilities supported by grant p ca . we thank r. muthuramam for technical assistance. e.w. is on the sab of forma therapeutics. j.h. is on the eab of chugai pharmaceuticals, is a consultant for novartis, and re- ceives research support from pfizer and novartis. received: july , revised: september , accepted: october , published: november , references bridges, h.r., jones, a.j., pollak, m.n., and hirst, j. 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( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref 	the genomic landscape of renal oncocytoma identifies a metabolic barrier to tumorigenesis 	introduction 	genomic analysis indicates two main subtypes of renal oncocytoma 	type oncocytoma may be the precursor of eosinophilic chrcc 	recurrent ccnd rearrangement and amplification in type oncocytomas 	p is a barrier to oncocytoma progression 	type and oncocytomas display mitochondrial defects and metabolic stress 	oncocytomas manifest phenotypes of defective autophagy 	mitophagy is primed, but not executed, in oncocytomas 	impaired mitochondrial respiration in primary oncocytoma cells 	oncocytomas display lamp- trafficking, golgi, and lysosome defects 	complex i inhibition and golgi disassembly block autophagy 	discussion 	experimental procedures 	tumor samples 	whole-exome and rna-sequencing data analysis 	accession numbers 	supplemental information 	author contributions 	acknowledgments 	references increased incidence of heater-related burn injury during a power crisis increased incidence of heater-related burn injury during a power crisis tina l. palmieri, md; david g. greenhalgh, md hypothesis: recent power shortages in california re- sulted in rolling blackouts and increased utility prices. residents turned to alternative heating devices, such as space heaters, to decrease utility bills. our hypothesis is that the incidence of heater-related injuries increased ow- ing to the use of alternative heating methods during the power crisis. design: retrospective case-series database and medi- cal record review of all burn admissions for the months of november through february for the period - . setting: regional pediatric and adult burn unit in north- ern california. patients: patients admitted during the study interval with burn injury. main outcome measures: parameters recorded in- cluded patient demographics, cause of burn, total body surface area burn, number of operative procedures, and hospital length of stay during each of the months in the interval. results: a total of patients were admitted during all -month intervals. during the power crisis there were significant increases in the number of hospital admis- sions ( in - vs in - , in - , and in - ) and heater-related burn admissions ( in - vs in - , in - , and in - ). the percentage total body surface area burn (mean ± sem, . % ± . % in - vs . % in - , . % in - , and . % in - ), hospital length of stay ( . days in - vs . days in - , . days in - , and . days - ), and the number of operations ( in - vs in - , in - , and in - ) also in- creased during the crisis. conclusions: the number of heater-related burn ad- missions, as well as their magnitude, increased during the energy crisis, resulting in increased resource use and health care costs. the economic stresses of the power shortage had societal costs that extended far beyond the price of electricity. arch surg. ; : - t he power shortage in north- ern california from novem- ber through february resulted in a substan- tial increase in the price of natural gas and electricity throughout the state. as a result many residents, in an at- tempt to lower their utility bills, took a va- riety of measures to decrease these costs, ranging from lowering the temperature on the thermostat to the use of alternative heat- ing sources such as space heaters, wood- burning stoves, and fireplaces. improper or inadequate use, installation, or supervision of these devices can result in house fires or direct burn injury from the heating source. each year more than per- sons are admitted to burn units with se- vere burns. the incidence of burn in- jury, owing to a variety of reasons, has been decreasing over the last years. how- ever, the number of admissions to the uni- versity of california davis regional burn center and shriners hospitals for chil- dren northern california burn center in- creased markedly during the winter months of - , coinciding with the peak of the energy crisis. although the financial and eco- nomic consequences of the energy short- age have been widely publicized, the po- tential increase in burn injury and its socioeconomic effect have not been ex- plored. the purpose of this study is to de- termine if the incidence in heater-related injuries in northern california increased during the power crisis. patients, materials, and methods the study was approved by the university of cali- fornia at davis institutional review board. the university of california at davis regional burn center and shriners hospitals for children northern california burn center admit pa- tients from northern california, the central val- ley, and the adjacent states. analysis of the trauma registry of the american college of sur- geons burn database and retrospective patient original article from the shriners hospitals for children northern california burn center and department of surgery, university of california at davis regional burn center, sacramento. (reprinted) arch surg/ vol , oct www.archsurg.com © american medical association. all rights reserved. downloaded from: https://jamanetwork.com/ by a carnegie mellon university user on / / medical record review was completed for all burn admissions in the months from november through february in years through . medical records were reviewed for patient demo- graphics, cause of burn, percentage total body surface area (tbsa) burn, survival, number of operative procedures required, and hos- pital length of stay (los). the mean monthly temperature for each of the study months was obtained from the western re- gional climate center. differences between the total number of burns, heater-related burns, and the number of heater-related burns by month during the power shortage months (november - february ) were compared with each of the periods im- mediately prior (november -february and november -february ) as well as to the ensuing year (november -february ) using the � test. mean hosptial los and tbsa burn percentage differences between the power shortage months and each of the other intervals were compared using the t test. results are given as the mean (sem). results a total of patients were admitted in the months from november through february in - . there was a sig- nificant increase (p�. ) in the incidence of heater-related burn injuries between the - period and each of the previous years as well as in the subsequent year (table, figure , and figure ). there was a significant increase in the tbsa burn, with mean burn size greater than % in the - period vs the previous and subsequent years (figure ). the number of operations also increased markedly, with operations performed in - , in - , in - , and in - . the male-female ratio of patients with burn injury was . in - , . in - , . in - , and . in - . the most common causes of the burn are house fires, lighting a heater, and direct contact with a heater (figure ). to control for the potential effect of tempera- ture on the incidence of heater burns, the mean california temperature for each of the study months was obtained from the western regional climate center. the mean tempera- ture in each of the study months did not differ significantly between any of the study intervals (figure ). the greatest increase in heater-related burn injuries occurred in january . coincidentally, on january , , pacific gas and electric increased rates by . %, and south- ern california edison raised rates by . %. as the shortage became more severe, stage alerts (declared when an op- erating reserve shortfall of . % is unavoidable or when the operating reserve is forecast to be � . % after using all avail- able resources) were instituted. on january and , , rolling blackouts were ordered statewide. a statewide stage alert continued for consecutive days. the rate of ro- tating blackouts increased from in to in the pe- riod from january to may , . during this same in- terval, stages and notifications increased from to . - november - february november - february november - february november - february n o. o f a dm is si on s total admissions heater-related admissions ∗ figure . total number of burn admissions and heater-related burn admissions during the winter months (november-february) for - . the percentages of heater-related burns increased significantly during november through february compared with november through february , and november through february (p�. , � test). asterisk indicates significant differences. november december january february n o. o f a dm is si on s - - - - ∗ ∗ figure . distribution of heater-related burn injuries by month. a significant increase (p�. , � test) in burn injuries occurred in the period - compared with the - , - , and - periods. asterisks indicate significant differences. demographic data of burn admissions during study period* interval total no. of admissions total no. of heater-related injury admissions age, mean (sem), y tbsa burn, mean (sem), % hospital los, mean (sem), d no. of or november -february . ( . ) . ( . ) . ( . ) november -february . ( . )† . ( . ) . ( . ) november -february ‡ . ( . ) . ( . )§ . ( . )§ november -february . ( . )† . ( . ) . ( . ) *tbsa indicates total body surface area; los, length of stay; and or, operations. †p�. by t test compared with - totals. ‡p�. by � test compared with november through february , november through february , and november through february totals. §p�. by t test compared with november through february , november through february , and november through february totals. (reprinted) arch surg/ vol , oct www.archsurg.com © american medical association. all rights reserved. downloaded from: https://jamanetwork.com/ by a carnegie mellon university user on / / comment the fiscal impact of the california energy crisis has been the focal point of published reports. the financial ef- fects of the shortage on california power companies, the state, and consumers have been well documented. cali- fornia residents were encouraged to conserve electricity and gas during times of severe shortages, and the high cost of electricity further reinforced this request. mea- sures taken to conserve energy ranged from decreasing the set point on the thermostat to using alternative de- vices such as space heaters, wood-burning stoves, and fireplaces. cost restraints frequently lead people to use unsafe heating sources. these alternative heating sources have the potential to cause serious injury if not used prop- erly. to our knowledge, to date the potential effect of the shortage on consumer health has not been addressed. this article is the first to document an increase in con- sumer-related burns after the implementation of rolling blackouts and increased energy costs. the greatest in- crease in the incidence of heater-related burns occurred in january , coinciding with the electricity rate increase and the institution of blackouts. the increased number and severity of burn injuries, as indicated by a significantly greater number of operative procedures performed dur- ing this period, had a detrimental effect on consumer physi- cal and financial health. this will likely result in long- term morbidity for the affected consumers. prevention of these injuries could result in lower financial and con- sumer health costs. implementation of preventive strate- gies, such as installation of smoke detectors in homes, have been successful in decreasing the incidence of burn in- jury. - a similar strategy may well be of benefit in pre- venting heater-related burn injuries in the future. al- though economic or societal events may increase the risk of this type of burn injury, education regarding appropri- ate behaviors in response to the power shortage may help to ameliorate these effects. the full impact of the california energy crisis re- mains unclear. although current studies have centered on the financial impact of the crisis, further investigation into the effects on consumer health needs to be undertaken. this study was presented as a poster at the pacific coast sur- gical association meeting, las vegas, nev, february , . corresponding author: tina l. palmieri, md, depart- ment of surgery, university of california, davis, stock- ton blvd, suite , sacramento, ca (e-mail: tina.palmieri@ucdmc.ucdavis.edu). references . american burn association. initial assessment and management. in: sheridan rl ed. advanced burn life support course instructor’s manual. chicago, ill: ameri- can burn association; : - . . brigham pa, mcloughlin e. burn incidence and medical care use in the united states: estimates, trends, and data sources. j burn care rehabil. ; : - . . western regional climate center. available at: http://www.wrcc.dri.edu/cgi-bin. accessed february , . . national energy information center. available at: http://www.eia.doe.gov/cneaf /electricity/california. accessed february , . . california power exchange. available at: http://www.calpx.com. accessed feb- ruary , . . federal energy regulatory commission. order directing remedies for califor- nia wholesale electric markets. december , . . california public utilities commission and electricity oversite board. california’s electricity options and challenges. report to governor gray davis. august , . . sheffrin anjali. california independent system operatory: what went wrong with california electric utility deregulation? april , . . hall jr jr. the us experience with smoke detectors: who has them? how well do they work? when don’t they work? natl fire protection agency j. ; : - , - . . mcknight rh, struttmann tw, mays jr. finding homes without smoke detec- tors: one step in planning burn prevention programs. j burn care rehabil. ; : - . . gorman rl, charney e, holtzman na, roberts kb. a successful city-wide smoke detector giveaway program. pediatrics. ; : - . november - february november - february november - february november - february interval n o. o f p at ie nt s % tbsa burn length of stay, d ∗ ∗ figure . mean percentage of total body surface area (tbsa) involvement and hospital length of stay increased significantly in the interval from november through february compared with november through february , november through february , and november through february (p�. , t test). asterisks indicate significant differences. stove heater contact lighting heater house fire campfire fireplace n o. o f e ve nt s - - - - figure . causes of heater-related burns included contact burns with stoves, house fires, fireplaces, and campfires. ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) november december january february te m pe ra tu re , ° f (° c) - - - - figure . average ambient temperature in northern california during the interval from november through february - . (reprinted) arch surg/ vol , oct www.archsurg.com © american medical association. all rights reserved. downloaded from: https://jamanetwork.com/ by a carnegie mellon university user on / / research on the current situations and countermeasures for the energy security in china available online at www.sciencedirect.com energy procedia ( ) – – © published by elsevier ltd. doi: . /j.egypro. . . iaceed research on the current situations and countermeasures for the energy security in china luo yixin* departm ent of industry and com m erce managem ent,hunan college of finance and econom ics , p.r.china, abstract concretely , main p roblems in that security are analy zed, which ar e consid ered to affect chin a and mostly embody in such five big ar eas as the great p ressure in ener gy supp ly , the scarcity of relative energy resources, the shortage of green ener gy , the relative backwardness of ener gy technology and the drastic chan ge of the international ener gy market; furthermore the counter-measures concerned are p rop osed, including p erfecting the laws in ener gy , carry ing out the dip lomacy in energy actively and initiatively , saving ener gy and increasin g the ener gy utilization rate, develop ing the new technology of energy resources forcefully and exp anding green energy and new ty p es of energy . keywords: energy; safety; problem; countermeasure . introduction ene rgy is an important resource on which modern human survival and development depend. as china's economy booms, its demand for energy is growing. whether there is adequate and stable energy has become an important factor affecting and constraining china's economic develop entering the st century, energy prices climb up quic kly, repeatedly rewrit ing historical records. the ent. since ups and downs of international oil prices affect the world's nerves. accordin g to the estimat ion of authoritative international institutions, the proven recoverable oil in the world, can only supply around years of human needs (natural gas for - years, the coal about years), man is confronting the energy crisis which threatens energy security[ - ]. energy proble m has become a g lobal proble m. the thorough * corresponding aut hor. tel.: . e-m ail address: luoguiyuan@sina.com. open access under cc by-nc-nd license. © published by elsevier ltd. selection and peer-review under responsibility of riuds open access under cc by-nc-nd license. http://creativecommons.org/licenses/by-nc-nd/ . / http://creativecommons.org/licenses/by-nc-nd/ . / luo yixin et al. / energy procedia ( ) – settlement of the energy issues is related to resources, technology, environmental protection, finance, la w, regional security, counter-terroris m, and many other areas. no country can tackle it alone. therefore , for the common interests of sustainable human development, all countries in the world a re required to carry out close cooperation; in particular, the major energy producers and major energy consuming countries need to cooperate closely. in order to effectively deal with the world's energy crisis, our country has made tremendous efforts in environmental protection and energy security and achieved rema rkab le results. but because of various reasons, there are still a lot of problems we need to solve in the area of energy security in our country. . the main problems and the current status analysis on china's energy security china's energy security problems are mainly embodied in the following five areas: . . the big energy supply pressure and the relative shortage at present, our country is in the accelerat ion period of industrializat ion and urbanization, the energy consumption is of higher intensity. as the economy further e xpands its scale, energy de mand will continue to increase rapidly, which will create a great pressure on energy supply. the contradiction between supply and demand will e xist for long; oil and natural gas will further depend on imports. although the total amount of ch ina's energy resources is c onsiderable, the per capita is very low. resources exploration has lagged behind, which has impacts the imp rovement of energy production capacity. at the same time, our country has very uneven distribution of energy resources; large -scale and long-distance energy transport result in unsatisfying transporting capacity with increased cost. the latest data shows that china's dependence on oil imports reached percent, and is e xpected to grow to % by . in fact, the most important issue about energy secu rity is whether energy supply can support china's rapid economic gro wth or not. in recent years, the development in this regard is not in a normal situation: high energy-consuming industry is growing rapidly, driving the energy industry's rapid development. this results in the mutual promotion between the high energy -consuming industry and energy industry and their u ltra-high-speed development, leading to imbalance in the entire national economy. the research report released by npc financial and economic co mmittee shows that in recent years, the speed of rapid growth of high energy -consuming products is basically doubled in a fe w years. coal is not only the fuel for therma l power but also an important che mical ra w materia l. driven by the double forces, fro m to ch ina's coal output was nearly doubled in four years, fro m b illion tons to . b illion tons. even so, coal is still in shortage. provinces limited the e lectricity supply, and the coal used to generate electricity was in great need. fro m to , in these years, china's gdp average annual growth rate was . percent, ach ieving the first goal of quadrupling ahead of schedule. during this period, the average annual energy consumption growth was . percent, achiev ing the goal of doubling energy consumption to ensure quadrupling the gdp. if that were a llo wed to develop this way, not to say doubling energy consumption to quadruple the gdp, even if we quadruple energy consumption, we cannot ensure quadrupling gdp growth. relevant departments ma ke assumptions, in accordance with the e xisting mode of growth, to achieve the goal of quadrupling gdp ratio by , at least . billion tons of coal will be required. in fact it is the situation that leads to frequent mining accidents. high -energy consuming industries has driven the demand for electric ity, and thermal electric ity has driven the coal de mand. insufficient coal supply cannot satisfy the market, thus coal prices soaring which ma kes a number of s ma ll coal mines’ profits doubled and redoubled. ultra -high profits encourage some people to take risks. this is the deep -seated reason for the continuous mine accidents. production safety inspection results show that / of two billion tons of luo yixin et al. / energy procedia ( ) – coal in our country, that is, there is aroun d million tons of coal are produced by the mines unavailable of the safety conditions of coal production. most people think that china is very rich in coa l resources, and it is not true. expe rts who conducted inspections in xinjiang and inner mongolia found that the coal long-term reserves there are about one trillion tons, but the extractable reserves are far less than the figure. now the reserves available for e xploitation a re only billion tons. to achieve the goal in , we need to find bil lion tons of reserves available for e xp loitation. therefore, our resources are not very rich, but not enough. in addition, on the one hand, resources are in shortage, while on the other hand, waste is very serious. jia zhijie pointed out that the national average recovery rate of coal is only %, and many sma ll mines’ recovery rate is only % to %, while in developed countries this data is much as - %. . . the lack of green energy coal is ch ina's basic energy, and it is difficult to change the energy structure that china is rich in coa l, lack of gas, and short of oil. china's coal clean ing using level is low, and the pollution caused by coal combustion is serious . if this situation continues, it will bring greater pressure on the ecological environment. at present, pollution caused by the use of coal and da mage to the ecological environ ment in china a re a lso very serious. data shows that china’s emission of sulfur dio xide ranks first in the world and carbon dioxide e missions ranks second in the world a fter the un ited states . once our country is constrained by the "kyoto protocol”, the situation will be very serious. take shanxi province as an e xa mple , one ton of coal min ing leads to loss of million tons of water and loss of eight tons of reserves and associated ores. the indiscriminate digging at the mo ment has also brought the ecology and vegetation damage. these are realities that we have to face. . countermeasures . . perfect the relevant energy laws practice shows that one of the ma in proble ms is the lac k of a corresponding la w. therefore , it is an urgent need to develop our country's energy security leading law. according to the latest reports, top leaders of our country have paid great attention to questions of energy, not only increas ing more than organizations for the bureau of energy under national deve lopment and reform co mmission in , more importantly, they have made instructions to enact china's "energy law" as soon as possible [ - ]. at present, our country already has "coal law", " electric ity act" and other relevant law. " energy la w" will be the top law of these laws. in the past, our manage ment of coal resources was only concerned about their physical property, that is, only managed these resources as fuels. on august , , u.s. president george w. bush signed a new energy bill, "national energy po licy act of ." so me e xperts consider it as the most e xtensive energy of the world in the last years. according to the briefing, this us new energy la w main ly include the following contents: provide consuming ta x pre ference, pro mote ho me energy effic iency; set a new min imu m energy effic iency standard, improve the effic iency of comme rcia l and household appliances; through tax incentives, repeal outdated provisions not conducive to infrastructure investment, to strengthen and upgrade the national power grid and other energy infrastructure; through tax cuts and other measures to promote renewable energy development and utilization; support energy -efficient automobile p roduction ; reduce dependence on foreign energy sources etc. expe rts have long suggested that although the chinese have "coal la w", " electric ity la w", " energy conservation law", " renewable energy la w", we still lack of a "leading" basic ene rgy la w. and the luo yixin et al. / energy procedia ( ) – legal status and the principle for adjusting "oil law", "natural gas la w "and" "atomic energy act," need further study. in addition, some of the e xisting energy laws and regulations cannot adapt to the needs of the reform and development, or even become obstacles to reform, and new things arising from re form or organizations lac k legal basis and legal protection. in addition to the new birth of the " renewable energy la w", other laws are necessary to be revised. national depart ments did have the plan to revise these laws, but the progress is slow, and some even co me to a halt. because there is not a basic energy law at the top, the amendments to the laws lack of a guiding principle for co -ordination. . . positive and proactive in carrying out energy diplomacy according to international finance news reports, china's current dependence on foreign energy is a big constraint on china's development. it is predicted that china's future energy supply and demand gap will be bigger and b igger. according to international pract ice , when a country's oil imports reach more than million tons, it often needs to use diplo matic and economic means to ensure oil security. in fact, energy diplo macy has become the third aspect in ch ina's diplo mat ic strategy, second only to big power diplomacy, and surrounding diplomacy. at present, china has been carrying out a "going out" strategy to encourage energy enterprises "going out", to participate in the global energy openness, by increasing the supply of energy all over the world to protect china's energy needs. we need oil, so we should set up a good relationship with those oil- producing countries, as well as those potential oil -e xport ing countries. in fact, especially entering , china's energy diplo macy has been very active. the series of dip lo matic actions in the new yea r serve only as a pre lude to the future chinese energy diplo macy. over the past, in the energy issue, ch ina always let a large-scale do mestic energy co mpanies fight on their own and did not want to cooperate with other countries. china, therefore, got the final price often h igher than the actual price, resulting in a certain degree of "disadvantage." at present, china has good relations with almost all oil-producing countries. ideological diffe rences will not lead to the breakdown of energy cooperation. this is resulted fro m ch ina’s moderate fo reign policy pursued in international polit ics and adherence to the principle of equality and mutual benefits in international econo mic and trade e xchanges. the kind of v iew to regar d energy diplo macy as a self -suffic ient energy supply policy precisely lacks of strategic vision. although in the past few years, the international co mmunity has critic ized and alerted on the efforts of china to obtain overseas energy supply sources, china's sustained economic develop ment is essential to the stable development of world economy. there fore, china's fore ign policy in energy on the one hand should not be undermined by crit icis m and pressure; on the other hand, it is necessary for china to acquire a stable source of overseas energy supplies and use it as a means to promote the benefits and dispel misgivings with all stakeholders and relative countries. . . save energy and improve energy efficiency on the one hand, compared with developed countries, china's energy utilizat ion effic iency is lo w. gdp produced by per unit energy consumption, is equivalent to only / of developed countries. for e xa mp le, china's total energy consumption is as much as . times of japan's, but its total gdp is only a bout percent of japan’s. the key to china's low energy effic iency lies in the high proportion of low -grade industrial structure and high-energy-consuming industries such as steel, e lectrolytic a lu minu m and cement etc. the proportion of those low-energy-consuming, h igh value-added industries such as electronic informat ion, precision manufacturing and third industries is too low. because of the sole pursuit of economic growth and product quantity, so as to ignore product quality and economic benefits for a long time , china has formed an e xtensive growth mode with the characteristics of h igh -consumption, luo yixin et al. / energy procedia ( ) – high input, and low-effic iency. even though we have been aware of the proble m, because of the lack of effective mechanisms and policies, therefore, this lon g-term pro minent contradiction restricting china's healthy economic development has not been fundamentally resolved, despite that we have indeed achieved certain results in this respect. from to , under the condition that total energy consumption was at zero growth or declined, gdp growth rate reached over . percent. but for the last three years, energy consumption elasticity coefficient rose markedly. fro m to , they were respectively . , . , . and l. . in , energy consumptio n grew . percentage points more than total gdp growing rate, but it still fa iled to satisfy the demand. on the other hand, ch ina's energy -saving potential is huge. at p resent, the main energy -consuming equip ment and technologies are outdated. high energy-consuming products’ per unit energy consumption is about % mo re than the developed countries on average, and china’s energy consumption of per unit output value is . times of the world average level. since the "ninth five-yea r plan", the energy conservation work has achieved remarkable results, the energy consumption of , yuan gross domestic product value dropped by % and the energy effic iency reached . % , energy -saving rate ranking top in the world. however, energy conservation work can only be counted as a start, and a lot of things are still required to do. china's energy-saving should first start from the conservation of energy resources. it is necessary to close the small coal mines which undermine the bigger ones. meantime, the state shou ld be determined to rectify the high-energy-consuming industries, close in accordance with the law the industrial enterprises leading to the destruction of resources, waste of energy, damage to the ecology, and serious pollution. for those enterprises with high energy, materia l and water consumption, the state should be determined to technologically transform them. . summary ) china's energy security situation is very serious, which we need to seriously deal with; ) ch ina's energy security problems are ma in ly reflected in the energy supply pressure, the relative shortage of energy resources, lack of green energy, relat ively backward energy technology and the changing international energy ; ) put forward co rresponding measures such as set up a sound ene rgy law, actively ca rry out energy diplo macy, energy saving and improve energy effic iency, vigorously develop new energy resources technologies, green energy and new energy etc. references [ ] kong lingbiao, feng shu-hu. regarding quest ions of energy security chinese coal. 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Özdemir, m.; mihmanh, m.; Çevikba⅜ u. does fibrin glue improve drainage after axil- lary lymph node dissection? prospective and randomized study in humans vaxman, f.; kolbe, a.; stricher, f.; zund, d.; volkmar, p.; gros, d.; grenier, j.f. original paper evaluation of water molecules in the cold- preserved rat liver by proton magnetic resonance imaging yanabu, n.; tanaka, a.; sato, b.; mori, s.; kitai, t.; tokuka, a.; inomoto, t.; yamaoka, y.; morikawa, s.; inubushi, t. effect of the combination of human thiore- doxin and l-cysteine on ischemia-reperfusion injury in isolated rat lungs wada, el; hirata, t.; decampos, k.n.; hitomi, s.; slutsky, a.s. effect of octreotide acetate on pancreatic exocrine and endocrine functions after pancrea-toduodenal resection petrin, p.; antoniutti, m.; zaramella, d.; da lio, c; basso, d.; plebani, m.; panozzo, m.p.; costantino, v.; pedrazzoli, s. role of platelet-activating factor antagonism in haemorrhagic shock in pigs abu-zidan, f.m.; walther, s.; lennquist, s. hepatic cholesterol α-hydroxylase activity and serum α-hydroxycholesterol level during liver regeneration after partial hepatectomy in rats nakano, k.; chijiiwa, k.; okamoto, s.; yamashita, h.; kuroki, s.; tanaka, m. inhibition of hepatic regeneration after % partial hepatectomy by simultaneous resection of the bowel in rats miyazaki, m.; kohda, s.; itoh, h.; kaiho, t.; kimura, f.; ambiru, s.; hayashi, s.; gohchi, e.; takanishi, k.; nagai, m.; togawa, a.; nakajima, n. influence of dextrans on cardiac preservation in an extracorporeal rat heart model albes, m.; baumgärtel, i.; rohde, r.; hausen, b.; demertzis, st.; wahlers, th, abstracts th walter brendel symposium on applied immunology and microcirculation axams, tirol, january to february , announcement author index vol. , subject index vol. , v suppl. european society for surgical research (essr) abstracts th congress, amsterdam, the netherlands, may - , editors: t.m. van gulik, amsterdam; pj. klopper, amsterdam; d.w. meijer, amsterdam; j.j.g. bannenberg, amsterdam vi envisioning carbon-free land use futures for sweden: a scenario study on conflicts and synergies between environmental policy goals original article envisioning carbon-free land use futures for sweden: a scenario study on conflicts and synergies between environmental policy goals tom van der voorn & Åsa svenfelt & karin edvardsson björnberg & eléonore fauré & rebecka milestad received: december /accepted: february # the author(s) abstract in climate change mitigation, backcasting scenarios are often used for exploring options for achieving a single environmental goal, albeit at the expense of other goals. this paper assesses potential conflicts and synergies between multiple environmental policy goals based on four future scenarios on swedish rural land use, assuming zero ghg emissions in . the assessment shows that goal conflicts are apparent, and policy makers need to make trade-offs between goals. the choice of strategy for dealing with these trade-offs yields conflicts or synergies. the assessment shows that a transition to zero ghg emissions provides opportunities for sweden to shift to carbon free land-use planning. overall, there are alternative ways with different underlying assumptions to achieve zero ghg emissions, which will feed discussions on new opportunities to overcome multi-scale and multi-sectoral goal conflicts. multi-target backcasting scenarios are considered more suited to account for the multi-dimensional aspects of goal conflicts. this requires a comprehensive multi-target backcasting approach, which combines the strengths of multicriteria analysis, nexus approaches and backcasting, for supporting a transition to zero ghg emissions. keywords backcasting scenarios . goal conflicts . synergies . climate change mitigation introduction in the face of global climate change, there is growing interna- tional momentum to reduce carbon emissions and mitigate the impacts of climate change, with the paris agreement cherishing the aspiration to limit global temperature increase to . °c above pre-industrial levels (hooper et al. ). progressing from aspiration to action, decisions on climate change mitigation options are needed for reducing the socio- economic and socioecological impacts of climate change. this requires policy makers to have a sound understanding of all climate change mitigation options available and thor- ough approaches for making such decisions. over the last decades, scenario development has become commonplace in exploring climate change mitigation options (agnolucci et al. ; van drunen et al. ). the risk of irreversible climate change increases the need for more ambitious policy goals and actions (ipcc ), which also resonates in research show- ing that taking immediate action for extensive emissions re- ductions and full use of available technology may still limit global warming to below °c (luderer et al. ). therefore, it is an urgent matter to formulate what changes are actually required in order to achieve ambitious climate goals like the paris agreement’s long-term temperature goal. although exploratory scenario approaches have become mainstream in climate change mitigation research, particularly for the purpose of reducing carbon emissions and mitigating the effects of climate change (giddens ), they have lim- itations too (van der voorn et al. ). exploratory scenario approaches are well equipped for mapping uncertainties but do not account for normative preferences or desirability (quist ; van der voorn et al. ). by comparison, normative communicated by helmut haberl electronic supplementary material the online version of this article (https://doi.org/ . /s - - - ) contains supplementary material, which is available to authorized users. * tom van der voorn tvanderv@uni-osnabrueck.de institute of environmental systems research, university of osnabruck, barbarastr. , osnabruck, germany department of sustainable development, environmental sciences and engineering, kth royal institute of technology, stockholm, sweden division of philosophy, kth royal institute of technology, stockholm, sweden https://doi.org/ . /s - - - / published online: march regional environmental change ( ) : http://crossmark.crossref.org/dialog/?doi= . /s - - - &domain=pdf http://orcid.org/ - - - https://doi.org/ . /s - - - mailto:tvanderv@uni-osnabrueck.de foresight approaches such as backcasting are better equipped for the shortcomings of exploratory scenario approaches due to their applicability at various scales, their compatibility with various tools and methods and their ability to support various forms of stakeholder engagement (quist et al. ; van der voorn et al. ). backcasting has been proposed as a suit- able approach for developing low-carbon pathways and deal- ing with global climate change (giddens ). in climate change mitigation, scenarios, particularly backcasting scenarios, can play a role in illustrating what the future could be like when goals are fulfilled and what kind of societal transformations are required (robinson ; vergragt and quist ) and also contribute to a discussion of which priorities are to be made in decision-making process- es (höjer et al. ; van der voorn et al. ). a backcasting scenario refers to a description of how a desirable future may unfold base on a chain of ‘if-then’ propositions. although scenarios, particularly backcasting scenarios, gen- erate options for attaining mitigation targets, they do not typically account for potential conflicts between proposed measures and their impact on the fulfilment of multiple environmental goals (fauré et al. ). a goal conflict arises when efforts to achieve one goal (or set of goals) is at the expense of achieving another goal (or set of goals) (edvardsson-björnberg b). goal con- flicts can thus constitute major policy challenges for decision makers. unless goal conflicts are properly assessed, there is a risk that climate mitigation strategies will not only counteract the achievement of other goals and values but also reinforce existing vulnerabilities. edvardsson-björnberg ( a) have identified such conflicts regarding adaptation to climate change and con- cluded that adaptation measures can conflict with mitigation of climate change and also with other policy goals. in this paper, we describe how backcasting scenarios can support identifying conflicts between environmental goals. section proposes a definition of goal conflict and describes different approaches for dealing with such conflicts. section describes the approach for the qualitative environmental assess- ment of scenarios to identify conflicts and synergies in regard to a broad range of environmental targets (e.g., reduction of bio- diversity loss, viable habitats for flora and fauna). the scenarios illustrate options for the purpose of reduced climate impact and zero net emissions of greenhouse gases. the results of the as- sessment are presented in section . section discusses the results, whereas the methodological implications are discussed in section . the conclusions are presented in section . approaches for dealing with goal conflicts defining goal conflicts although interconnected, many global sustainability chal- lenges, like climate change, have been addressed separately, at times reducing one problem at the expense of another (liu et al. ). effective and sustainable solutions to these chal- lenges will require greater understanding and consideration of the linkages and interdependencies between these sectors such as water, energy and food. as a consequence of these interde- pendencies, decision makers in all sectors face the significant challenge of accounting for synergies, goal conflicts and po- tential trade-offs between these sectors at multiple spatial and temporal scales (leck et al. ). despite the central role played by goal conflicts in environ- mental decision making, surprisingly few systematic efforts have been made to define and categorise the various types of goal conflicts involved. nilsson et al. ( ) and nilsson et al. ( ) are two notable exceptions. there is an extensive lit- erature in philosophy, psychology, decision theory and related disciplines on value conflicts (keeney and raiffa ; levi ), conflicts of desires (marino ), interests (axelrod ), and practical dilemmas (hansson ; höijer et al. ). however, the policy implications of those theoretical works are seldom analysed, or even referred to, in the envi- ronmental policy literature. in this paper, it is not our ambition to elaborate on these policy implications, but rather propose a definition of goal conflict that can be used to explore appropriate approaches for dealing with such conflicts. in doing so, we first consider value conflict and goal conflict as two different, though complementary concepts. value conflicts refer to situations in which values are inconsistent, where- as goal conflicts concern situations in which desired end states or preferred outcomes are incompatible (le pelley et al. ). value conflicts are more fundamental than goal conflicts in the sense that they are firmly rooted in belief and cognitive systems. therefore, goal conflicts manifest themselves at a more operational level. in line with edvardsson-björnberg ( b), we refer to a goal conflict as a situation that often emerges from efforts to achieve one goal (or set of goals) at the expense of another goal (or set of goals). as noted by nilsson et al. ( ), there are different dimensions along which goal conflicts can arise. goal conflicts can occur within a single policy domain (e.g., between the biodiversity conservation goal of natural and cul- tural assests and ecosystem services), or they can involve dif- ferent policy areas (e.g., climate mitigation policy vs. transport access policy). goal conflicts can arise between goals set at the same institutional level (e.g., within a municipality or by a government), or they can involve different levels of gover- nance (e.g., eu policy goals vs. goals adopted at the member state level). in addition, goals can conflict in various degrees. nilsson et al. ( ) identify three degrees of goal conflict: constraining (efforts to achieve one goal limit options on an- other goal), counteracting (efforts to achieve one goal clash with another goal), and cancelling (efforts to achieve one goal make it impossible to reach another goal) interactions. page of reg environ change ( ) : multicriteria analysis many of the complex problems faced by decision makers involve multiple conflicting goals (leck et al. ). in the literature, several approaches can be found for dealing with conflicting goals. multicriteria analysis (mca) or multiobjective decision making, for example, is a type of de- cision analysis tool (larichev ). mca is particularly ap- plicable to cases where a single-criterion approach (such as cost-benefit analysis) falls short, especially where monetary values cannot be assigned to environmental and social im- pacts. mca allows decision makers to address a full range of social, environmental, technical, economic and financial criteria when dealing with complex decisions (silva et al. ). principally, mca is useful for dividing such decisions into smaller, more understandable and analysable parts and integrating these parts to produce a meaningful solution. however, the major shortcomings of mca arise when one option would be better against a second criterion but worse against another in the performance matrix. this is a matter of trade-off that occupies a central place in decision-making hav- ing multi-dimensional aspects. weighting or ranking becomes necessary to handle such cases, but with their own associated methodological difficulties. this becomes a really critical is- sue to which no fully satisfactory answer is available. mca is also weak with regard to making inter-temporal comparisons. when it comes to the selection of certain parameters (e.g., the inter-temporal discount rate), it is the lack of objectivity that can tilt the balance in favour of certain options over others (beria et al. ). consequently, mca runs short in address- ing normative aspects of trade-offs. nexus approaches nexus approaches have gained significant interest as a poten- tially effective approach for dealing with trade-offs and con- flicting goals (leck et al. ). recent studies have revealed that nexus approaches can uncover synergies and detect neg- ative trade-offs among sectors (daher and mohtar ). by identifying positive synergies and negative trade-offs, nexus approaches can support sustainability pathways through pro- moting high resource use efficiency, lower production of co emissions and wastes, and more coherent policies. many tools and methods can be used for quantitatively analysing nexus relations (liu et al. ). nexus approaches, if well imple- mented, have the potential to reduce unexpected conse- quences (rasul ). for example, due to the water intensive production processes involved, biofuels as part of the solution to decrease co emissions from burning fossil fuels have significant negative consequences for water scarcity and food security (lane ). nexus approaches can also promote integrated planning, management and governance. it does so, by accounting for cross-sectoral and transboundary interlinkages in planning and governance to ensure system resilience and sustainability in the face of future uncertainties. the system(s) of interest can be socially or spatially defined or bounded, and their boundaries may be geographical, political or administrative (conway et al. ). however, the application and implementation of nexus approaches are still in their infancy. to further implement nexus approaches and realise their potential, liu et al. ( ) emphasise the need for more systematic procedure and nexus frameworks that con- sider interactions among more sectors, across scales and be- tween adjacent and distant places. backcasting scenario development provides an approach for going beyond post-hoc analysis of environmental and social implications of negative trade-offs and positive synergies (hooper et al. ). scenarios can be seen as an assumed sequence or de- velopment of events, and can be either explorative (consider- ing the evolution of possible futures from pre-set storyline) or normative (exploring preferred ways to achieve a specific fu- ture objective), with also possible intermediate approaches (van vuuren et al. ). scenario development takes into account alternative futures and their evolution from the pres- ent, providing insights into the decisions required in the near- term, mid-term or long-term (hughes et al. ). normative scenarios, in particular backcasting scenarios, are used to ex- amine paths to alternative futures that vary according to their desirability (kok et al. ). these value-driven scenarios are often either preferable and optimistic, or disagreeable and pessimistic. such scenarios typically result from target- oriented backcasting, in which the emphasis is on the need to develop and describe images of the future as goal-fulfilling (höjer et al. ). a goal is typically expressed in a quanti- tative manner, such as % decrease in co emissions, but the route to that goal can be approached in a quantitative (feasi- bility of measures) and qualitative (desirability of measures) manner. the rationale for stressing goal fulfilment is that it challenges the imagination to identify more solutions and to go beyond what is considered probable or feasible according to mca. basically, target-oriented backcasting is about ex- ploring the question of what can change (wangel ). it is a key approach when uncertainty is high, the problem is com- plex and persistent, and a long-term view is essential (dreborg ). backcasting recognises the irreducibility of uncer- tainties about future developments (e.g., uncertainty associat- ed with climate and societal change) and externalities of ac- tions yet to be taken but also the need to account for these uncertainties by assessing the risks of undertaking (precautionary) action (höjer and mattsson ; quist et al. ). equally importantly, backcasting draws on an integrated systems approach for realising a whole systems change, taking page of reg environ change ( ) : into account the linkages and interdependencies between var- ious sectors (energy, water, food) or systems (e.g., social- ecological systems) (quist ; van der voorn et al. ; van der voorn et al. ). in this regard, nexus approaches and backcasting adopt an integrated approach for ensuring system resilience and sustainability. however, more efforts are yet needed to develop, implement and apply comprehen- sive nexus frameworks, incorporate overlooked drivers and regions, expand and diversify nexus toolboxes, mainstream nexus approaches into policy making, governance and man- agement and coordinate knowledge integration and stakehold- er engagement across sectors (liu et al. ). by compari- son, backcasting provides a more comprehensive approach for achieving system resilience and sustainability in climate change mitigation (sharmina ). backcasting is consid- ered suitable due to its applicability at various temporal and spatial scales, compatibility with various tools and methods, and its ability to support various forms of stakeholder engage- ment (quist et al. ; van der voorn et al. ). nonetheless, backcasting and nexus approaches are comple- mentary rather than conflicting approaches. in backcasting, there is the aim to assess the physical (quantitatively) and social feasibility (qualitatively) of the pathway towards a de- sired future. this assessment requires identifying the necessity of measures and actions for bringing about that future, but would also benefit from employing nexus tools and methods to quantify the positive or negative consequence of these measures. case study: emission scenarios for swedish rural land use introduction assessments of environmental goal conflicts are limited in the scientific literature, but in swedish environmental policy, goal conflicts have been on the agenda ever since a national system of environmental quality objectives was put in place in the late s. goal conflicts are discussed in several reports from the swedish environmental protection agency (sepa), both in terms of different interests or stakes that can create conflict and demand dialogue (almstedt et al. ), and in terms of conflicts between fulfilment of different goals or policy areas (sepa ). the sepa ( ) concludes that both synergies and goal conflicts are common in the swedish system of en- vironmental objectives, both internally (among the environ- mental quality objectives) and externally (between the envi- ronmental quality objectives and other environmental goals). however, knowledge about how different goals interact and how to address the problem of goal conflicts is at best limited and, thus, in need for further investigation. research method the scenarios used to test the assessment method described in this paper have been described in milestad et al. ( ). these scenarios illustrate the fulfilment of the swedish environmen- tal policy goals for reduced climate impact and zero net emis- sions of greenhouse gases. the assessment in this paper con- cerns how the scenario assumptions and adopted strategies for mitigating climate change could impose on or influence other environmental policy goals. this assessment of potential syn- ergies and goal conflicts was made through a systematic com- parison of the content of the four scenarios in relation to the swedish environmental goals, i.e. the swedish national environmental quality objectives (gov. bill / : ; gov. bill / : ; gov. bill / : ) and the over- arching generation goal (gov. bill / : ). one goal (a protective ozone layer) was omitted from the assessment since it has already been reached. the qualitative assessment of goal conflicts and synergies in this paper is made in relation to swedish environmental policy goals. since the method was used on scenarios for sweden, the swedish environmental quality objectives were used (sepa ). however, the assessment could just as well have been carried out in relation to other sets of policy goals, such as the global sustainable development goals (united nations general assembly ). the purpose of assessing scenario outcomes in relation to other policy goals is to avoid that goal conflicts are consid- ered as side effects, and that synergies are not taken into ac- count. we argue that if the results and suggestions of backcasting studies are to be useful to planning and policy, we need to make sure that there are no severe side-effects for societal policy objectives. the qualitative assessment draws on the scenarios and con- flicts identified by other authors in scientific papers, reports and policy documents (see, e.g., references to supplementary material). this was done first individually by one of the au- thors, and later the preliminary results were discussed and adjusted together with two of the authors in a workshop for- mat. this analysis is summarised using a compatibility matrix (table ). for each goal, aspects of the goal, as described in policy documents, were compared to the content of the sce- narios, and we focused on aspects that were described explic- itly in the scenarios and/or could be deducted from the scenar- io descriptions. description of the analysed scenarios the four scenarios that were analysed were developed in a swedish research project dealing with strategies for mitigating climate change (milestad et al. ) and are summarised in fig. . the scenarios describe images of the future when sweden has achieved a goal of zero ghg emissions in page of reg environ change ( ) : table synergies and conflicts between policy goals and mitigation of climate change in the scenarios centralised governance and biomass focus, centralised governance and electricity focus, localised governance and biomass focus and localised governance and electricity focus. red fields = conflict, green fields = synergy, white fields = no page of reg environ change ( ) : . the red thread in the scenarios is the link between an international climate change mitigation treaty and the energy sources used. the focus lies on describing how land in sweden can be used. in all scenarios, the import of goods and energy have decreased, there is less transportation, and the domestic production support area is sufficient for covering net consumption needs. results of the assessment the results of the assessment are summarised in table . the table indicates if potential goal conflicts or synergies have been identified in each scenario. for each swedish environ- mental quality objective, the aspects that the assessment fo- cused on are shown along with an indication of potential syn- ergies and conflicts. green colour indicates that there is syn- ergy, red colour that there may be a potential goal conflict between fulfilling the goal of zero emission with the other policy goals. if the box is white, no assessment could be made. in the supplementary material includes a more thorough ex- planation of the environmental quality objectives, the selected aspects, and a motivation for why these aspects are critical in the scenario assessment. the critical aspects are based on the specifications of the goals in the policy documents, the infor- mation was gathered from the swedish environmental objectives portal (sepa ). additional sources of infor- mation supporting the assessment are indicated in the table. the assessment shows that there are more potential goal conflicts in the biomass-based scenarios. it also shows that there are a lot of potential synergies in the electricity-based scenarios. the local electricity based scenario has the fewest potential conflicts, but the difference in comparison with centralised electricity based scenario is small. discussion in this paper, the conflicts and synergies identified in the as- sessment relate to strategies proposed by the scenarios and current swedish policies. these scenarios may not be repre- sentative for future policy developments. some conflicts and synergies may remain unrevealed, depending on how local and global contexts or the environmental policies change. for example, the assessment identified several synergies that were related to the intensity and scale of agricultural produc- tion. decreased use of pesticides and increased opportunities for nutrient recycling in the local scenarios could result in synergies with several environmental goals (supplementary material: item ). however, current policy does not favour small-scale and extensive farming, which is the main model in the local scenarios. the eu and swedish agricultural poli- cies, as well as the market development, rather work in the • global energy crisis and severe climate change • energy in sweden mainly large-scale based on biomass • large-scale intensive land-use • decreased imports and transporta�on • high urbanisa�on • high compe��on for land centralised governance biomass focus • sustainable global energy supply, less climate change • energy in sweden, mainly large scale electricity • large-scale land-use, with environmental considera�on • decreased imports and transporta�on • urbanisa�on • less compe��on for land centralised governance electricity focus • global energy crisis and severe climate change • energy in sweden mainly small-scale based on biomass • small-scale land-use • local self-sufficiency • ruralisa�on • high compe��on for land localised governance biomass focus • sustainable global energy supply, less climate change • energy in sweden mainly from electricity • small-scale land-use, with environmental considera�on • local self-sufficiency • ruralisa�on • less compe��on for land localised governance electricity focus fig. summary of characteristics of the four scenarios, showing central features as regards the energy system, the global context and land use page of reg environ change ( ) : opposite direction. for example out of dairy farms have closed down in sweden in the past years although milk production has only decreased by % (sba ). this means that the strategy of increased local self-sufficiency can- not be used for mitigating climate change unless there are policies that counteract this development. as illustrated in table , in this assessment, more potential conflicts with other environmental goals were identified in the biomass-based scenarios. these scenarios assume develop- ments in which there is no climate agreement and where sweden carries on in fulfilling the zero emission target any- way. many of these conflicts are related to use of biomass for energy and fuel (concerns several goals related to traffic) and large allocation of land for energy production (e.g., conflicts related to the goals thriving wetlands and sustainable for- ests). the potential conflicts are related to several different issues, many of which could be avoided with sound measures and strategies. the conflicts related to competition over land is a result of intensive land use, which creates conflicts with aspects that require less pressure on the land, such as diversity in the agri- cultural landscape (supplementary material: item ). in the scenarios, these conflicts are also related to the use of biomass for energy supply because they are dependent on whether the transition to a zero ghg emission society is planned: either in collaboration with other countries and accompanied with in- vestments for an electricity-based energy system, or done more in isolation with less room and time for investments (in a global energy crisis). a quick transition is likely to be based on biofuels, and increased use and intensive cultivation of biofuels might lead to several potential goal conflicts, e.g., emissions from biofuels and effects on biodiversity (supplementary material: item ). regardless of these as- sumptions, possibilities for avoiding conflicts over land use lie in decreasing pressure on the land resource. that is to say that land-demanding activities are reduced or replaced. in these scenarios this is done in the electricity-based scenarios through development of electricity as a source of energy. based on the assessment summarised in table , one could argue that the pursuit of a transition to zero ghg emissions in sweden is only meaningful if it coincides with global efforts to transition to zero ghg emissions. however, the results of the assessment provide no evidence for this argument because the scenarios do not account for future developments in the rest of the world. when other countries/regions face an energy crisis without being prepared for it (as the storyline in the biomass-based case describes), the situation there may be- come much worse economically and socially than described in the same scenarios for the swedish context. secondly, some conflicts (e.g., expansion of forestry in conflict with a magnif- icent mountain landscape, table : items and ) directly relate to climate change and appear if global ghg emissions are not sufficiently reduced. and thirdly, if sweden would take the lead in demonstrat- ing that achieving zero ghg emissions is realistic, and also potentially beneficiary in the long term, it could inspire other governments. to aid the transition to zero ghg emissions, the swedish government can play a pro-active role in the creation of lead markets for renewable energy innovations. lead mar- kets of environmental innovations may lead to price advan- tages, demand advantages, transfer advantages, export advan- tages and strict regulation (porter-effect) in the long run (beise and rennings ). methodological implications most backcasting scenarios like the ones analysed in this pa- per relate to the fulfilment of one single target (höjer et al. ; svenfelt et al. ). the essence of backcasting sce- narios is to illustrate that transitions to zero ghg emissions are possible, by going beyond the hindering structures in the present (dreborg ). however, if potential goal conflicts or problems are not adequately addressed, there is the risk that the implemented measures may have unexpected and unin- tended side-effects like social or environmental impacts. traditional scenarios usually opt for one specific goal regard- less of other goals, which can lead to an accumulation of conflicts albeit unintentional. we argue that a solution to this dilemma is multi-target backcasting scenarios. such scenarios provide a way to avoid goal conflicts, by addressing several goals simultaneously (svenfelt et al. ). however, post- poning mitigation action simply to avoid potential conflicts with other policy goals is a short-term solution that is unlikely to render significant benefits in the long run. avoidance is likely to incur additional future costs (stern ). a con- scious decision not to take any mitigation action is considered a conflict-postponing strategy rather than a way of preventing goal conflicts. therefore, we suggest that it is important to investigate the dynamics of conflicts and synergies across dif- ferent temporal scales (short-term, mid-term and long-term) and spatial scales (local, national and global) and sectors (in- dustry, energy, food and water). the development of multi-target backcasting scenarios can be methodologically challenging because how does one man- age several targets simultaneously? one such multi-target sce- nario study has been carried out by svenfelt et al. ( ) in sweden, in which four sustainability targets were used as a basis to develop scenarios for sustainable futures beyond gdp-growth. more efforts are yet needed to develop a comprehensive approach for multi-target backcasting. the development and application of such an approach would also benefit from a methodological extension to nexus approaches and mca. as discussed in section . , nexus approaches and backcasting can be seen as complementary approaches. both page of reg environ change ( ) : adopt an integrated, systems approach for ensuring system resilience and sustainability, taking into account the linkages and interdependencies between various sectors or systems. goals may be motivated by practical problems that require understanding of specific interrelationships among various sectors or analysing nexus dynamics across these sectors. the analysis of nexus relationships can be supported by using a variety of tools and methods such as life-cycle assessment, material flow analysis and input-output analysis. these tools and methods can also support identifying the necessary mea- sures and actions for bringing about that future, but also to quantify the positive or negative consequence of these mea- sures. however, nexus approaches run short in addressing normative aspects (desirability) in resolving goal conflicts. to some extent, mca can be useful for dividing goal con- flicts into smaller, more understandable and analysable parts and integrating these parts to produce a meaningful solution. as argued by munda ( ), providing systematic informa- tion about goal conflicts can help to arrive at political com- promises by making a complex situation more transparent to policy-makers and lay people. as discussed in section . , mca becomes rather challenging when facing the lack of objectivity that can change the balance in favour of certain options over others. although mca typically falls short in addressing normative aspects of trade-offs, there are examples of participatory mca studies e.g., (garmendia and gamboa ), where the idea was to bring together actors so that different values can be raised. in this regard, mca and multi-target backcasting can play complementary roles: mca is useful for prioritising between different options, whilst multi-target backcasting can address normative aspects in priority setting. in sum, a comprehensive approach for multi-target backcasting, which combines the strengths of mca, nexus approaches and backcasting, would have the potential to ensure system resilience and sustainability. conclusions in this paper, we assessed four future scenarios on swedish rural land use in light of a transition to zero ghg emissions in . the scenarios include many goals to reach out to a non- fossil fuel future. the assessment shows that goal conflicts are apparent and policy makers need to make trade-offs between goals. the choice of strategy to meet a goal can resolve con- flicts or create synergies. the following major conclusions can be drawn from the assessment. firstly, a transition to zero ghg emissions provides opportunities for sweden to shift to a carbon free land-use planning and carbon free society. secondly, land use and how to deal with competition over land is a pressing issue if climate change mitigation is to be taken seriously. thirdly, extracting electricity from wind, wa- ter and sun relieves pressure on land resource. overall, there are alternative ways with different underlying assumptions to achieve zero ghg emissions, which will feed discussions about future goal conflicts in climate change mitigation. different perspectives on mitigation strategies and the diffu- sion in the creation of lead markets for renewable energy innovations will provide new opportunities to overcome fu- ture goal conflicts. the main benefit of analysing the nature of goal conflicts and suggesting potential strategies for resolving them is that goal conflicts can be anticipated in early phases of planning and management processes. one way to do so is through using scenarios and integrating the analysis of conflicts and synergies into an iterative, participatory scenario development process. a step further would be to develop multi-target scenarios, which are better equipped to deal with the drawbacks of single-target scenarios. the development and application of an approach for multi-target backcasting would benefit from a methodological extension to nexus approaches and mca. a comprehensive multi-target backcasting approach, which combines the strengths of mca, nexus approaches and backcasting, would have the potential to ensure system resilience and sustainability and support a transition to zero ghg emissions. funding information open access funding provided by projekt deal. the research presented in this paper was funded by the swedish research council formas. open access this article is licensed under a creative commons attribution . international license, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the creative commons licence, and indicate if changes were made. the images or other third party material in this article are included in the article’s creative commons licence, unless indicated otherwise in a credit line to the material. if material is not included in the article’s creative commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. to view a copy of this licence, visit http://creativecommons.org/licenses/by/ . /. references agnolucci p, ekins p, iacopini g, anderson k, bows a, mander s, shackley s ( ) different scenarios for achieving radical reduc- tion in carbon emissions: a decomposition analysis. ecol econ : – . https://doi.org/ . /j.ecolecon. . . almstedt m, 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- - https://doi.org/ . /s - - - https://doi.org/ . /j.futures. . . https://doi.org/ . /j.techfore. . . https://doi.org/ . /j.techfore. . . https://doi.org/ . /j.techfore. . . 	envisioning... 	abstract 	introduction 	approaches for dealing with goal conflicts 	defining goal conflicts 	multicriteria analysis 	nexus approaches 	backcasting 	case study: emission scenarios for swedish rural land use 	introduction 	research method 	description of the analysed scenarios 	results of the assessment 	discussion 	methodological implications 	conclusions 	references effect of gibberellic acid (ga ) on enhancing flowering and fruit setting in selected arab univ. j. agric. sci., ain shams univ., cairo, ( ), - , (received april, ) (revised june, ) (accepted july, ) performace evaluation of solar photovoltaic pump for operating of landscape system [ ] swidan, b.m. and m.m. mostafa agric. eng. dept., fac. of agric., ain shams univ., cairo, egypt keywords: solar water pumping; pumping sys- tem; photovoltaic water pumping; landscape; per- formance evaluation abstract most landscapes requires the water essentially, water pumping consumes a significant amount energy. the study carried out to evaluate the per- formance of a solar water pumping system for the purpose of operating landscape system. the sys- tem consists of a centrifugal water pump connect- ed directly to dc electric motor that which con- nected directly to a solar photovoltaic generator. field test had been carried out at menofia gover- norate, egypt. measurements were taken every hour starting from : am to : pm through randomly selected days during the period between august and february . results show the relation between the solar radiation and the output electrical power, hydraulic power, pumping rates and the efficiency of the system. system evalua- tion was carried out by estimating the intensity of solar radiation, photovoltaic output power and the hydraulic power generated. the pv output power was w at solar radiation intensity of w/m². also, photovoltaic generator and pumping system efficiencies were . % and . % respectively. introduction the world is witnessing in the current period, an increase in the steady population growth and a marked rise in the levels of culture, urbanization and luxury living. thus, the horizontal expansion of the building industry becomes the element that meets the needs and must be done to urban plan- ning standards, green spaces and public spaces in size up to % of the total area of the layout. most landscapes depends on water essentially, whether used in the water features such as fountains, wa- terfalls and pools or irrigate plants and even in the hydration and reduce air temperature. the pres- ence of water in the landscape like plants is of the most important elements that brings life to the landscape. water pumping consumes a significant amount of the electricity of the national grid and diesel fuel. on the other hand, egypt currently faces an ener- gy crisis due to the growing energy demand, in addition to fluctuating and increasing costs of en- ergy derived from fossil fuels. it is important to find ways of decreasing dependency on fossil fuels. the utilization of solar energy is good choice to face the energy crisis gawdat ( ). solar radiation on egypt ranges from to kwh/m per day with about sunshine hours per year, (sorensen, ). solar water pumping may be a competitive application for remote areas and luxurious areas where power costs a lot. (kaldellis et al ). nowadays, the utilization of pv conversion of solar energy to power the water pumps is an emerging technology with great challenges. the pv technology can be applied on a larger scale and it also presents an environmentally favorable alternative to diesel fuel and grid electricity as a power source for water pumps, (kumar et al and mittal et al ). solar photovoltaic water pumping systems (spvwps) providing domestic, livestock and irri- gation water supplies in remote areas have gained enormously in acceptance, reliability and perfor- mance. installing spvwps has many advantages to the pumping sites, where the national electricity grid connection is not available, solar energy is available abundantly, and the transport facilities are not good enough (ghoneim, ). furthermore, the use of solar photovoltaic power to operate the water pumping system is the most appropriate choice because there is a natural arab univ. j. agric. sci., ( ), swidan and mostafa relationship between requirement of water and the availability of solar power (hsieh, ). the solar energy systems are devices convert the solar radiation into other forms of energy. they can be divided into thermal effect and photo effect (non-thermal) systems, (yüncü et al ). the non-thermal solar systems or the solar photovoltaic cells (pvcs) directly convert sunlight into electricity which can be captured in the form of a direct electric current. this electricity can be used to power an appliance. the solar panels are therefore effective only during daylight hours and batteries will have to be utilized to provide an elec- tricity supply at other times, (carrasco et al and liserre et al ). in this respect a solar pumping system was tested to evaluate its performance under local working conditions. the objectives of this research are  use of photovoltaic to operate water pumping system for landscape.  study the factors that affect the pv pumping system.  evaluate the system performance. materials and methods the constructed system comprised of three stages; first stage was generating dc power from pv cells, second stage was converting dc power into mechanical power using dc motor and third stage was converting mechanical power into hy- draulic power using centrifugal pump. fig. ( ) shows the constructed system, which is designed to work in daylight hours only without the use of inverters (ac/dc) or battery banks for the storage of electricity. the system consists of the following elements fig. components of solar pumping systems and energy conversion steps. photovoltaic generator (pv) the basic photovoltaic module are presented in tables , and table . basic photovoeltaic module data model aleo p length x width x height [mm] x x weight [kg] number of cells cell size [mm] x cell material polycrystalline si front sheet solar glass (isg) back sheet polymer sheet, white frame material al alloy, silver table . photovoltaic module electrical data (stc) rated power pmpp [w] rated voltage umpp [v] . rated current impp [a] . open circuit voltage uoc [v] . short circuit current isc [a] . efficiency n [%] . electrical values measured under standard test condi- tions (stc): irradiance w/m², module temperature °c, air mass= . g performance evaluation of solar photovoltaic pump for operating of landscape system arab univ. j. agric. sci., ( ), table . photovoltaic module electrical data (noct). power pmpp [w] voltage umpp [v] . current impp [a] . open circuit voltage uoc [v . short circuit current isc [a] . efficiency n [%] .  dc powered motor; voltage: v (operates between and v.dc), max. speed: rpm and max. power: . hp.  centrifugal pump; characteristics of the water pump are presented in table ( ). table characteristics of the water pump: parameter value q. min l/min q. max l/min h. max m rpm water storage tank; the tank of water storage has dimensions of cm width, cm length and cm height. the photovoltaic system was implemented con- sists of four modules w each, manufacturer aleo, model p polycrystalline. pv array were installed with tilt angle º from the horizontal and faces the south direction. panels are connected in parallel to give a . a and . v total to gener- ate power for running dc motor pump system. the photovoltaic modules were installed on a rigid and fixed metal structure on the roof of two floor build- ing. the site was chosen because of the proximity to the water source and because it did not present trees or structures that could provide shade on the photovoltaic cells and damaging the performance. there was a greater concern with the positioning of the panels in relation to their alignment with the geographical north because its incorrect position- ing can lead to a decrease in the efficiency of the photovoltaic system. permanent magnet dc motor of a treadmill was used to convert electrical power form the pho- tovoltaic panels into mechanical power to drive the centrifugal water pump. ac motor equipped water pump manufacturer emc, was engaged to the system by connecting its shaft to the dc motor shaft using a coupling and fixed on one base. the technical specifications of the dc motor are: volt- age: v (operates between and v dc), maximum speed: rpm and maximum power: . hp. the technical specifications of the water pump are q.min.: l/min, q.max.: l/min, h. max.: m and rpm. the water tank was used as a reservoir of water, where it is providing the pump inlet with water and in the same time containing water from out stream, so that the system was working as a closed cycle of water to save water. measuring instruments were used to obtain data of the following parameters:  the output voltage and current from the pho- tovoltaic panels by digital electrical multime- ter;  water flow rate from the pump by electronic flow meter;  water pressure from the pump by analog pressure gage;  ambient air temperature behind the pv array by digital thermometer.  data were collected for months, beginning on august , , till th of february, , when the readings were performed every h. measurements were performed in order to evaluate the performance of photovoltaic solar pumping system and pv efficiency under condi- tions of different parameters affecting the perfor- mance. in order to study the energy conversion from solar radiation to water flow, the following six equations were used according to both hamza and taha ( ). the input power (pi) the incident solar radiation to the pv array gives the input power (pi) to the system: pi = g x a (w) ----------- ( ) where: g = solar radiation (w/m ) and a = effective module cell area (m ). pv array output (po) the dc output power (po) from the pv array is given by: po = v x i (w) ----------- ( ) arab univ. j. agric. sci., ( ), swidan and mostafa where: v = operating voltage (v) and i = operating current (a). hydraulic power output (ph) hydraulic power output of the pump (ph) is the power required to lift a volume of water through a given head ph = d x g x q x h (w) ----------- ( ) where: d = water density (kg/m ), g = specific gravity (m/s ), q = water discharge (m /s) and h = total pumping head (m). array efficiency (ηa) array efficiency (ηa) is the measure of how effi- cient the pv array is in converting sunlight to elec- tricity: ηa = po/pi x ----------- ( ) subsystem efficiency (ηs) subsystem efficiency (ηs) is the efficiency of the entire system components (motor and pump): ηs = ph/po x ----------- ( ) overall efficiency (ηo) overall efficiency (ηo) indicates how efficiently the overall system converts solar radiation into water delivery at a given head: ηo = ph,/pi x or ηo = ηa x ηs ----------- ( ) results and discussions the input power during the test period of this photovoltaic pumping system (august, – february, ), solar radiation ranged between to w/m /day on the plane of the pv modules. fig. ( ) shows hourly average incident solar radiation. the maximum value of the solar radiation was . w/m at : pm. the incident solar radiation to the pv array gives the input power (pi) to the system. the max- imum value of input power to the system was . w/m /day at : pm. fig. ( ) shows the average input power ob- tained during the experiment period. fig. . daily hourly average solar radiation. a v e ra g e s o la r ra d ia ti o n ( w /m ) day time (hr) performance evaluation of solar photovoltaic pump for operating of landscape system arab univ. j. agric. sci., ( ), fig. . average input power to the system (w/day). pv array output generated electric power fig. ( ) shows hourly average output power ob- tained during the experiment period with the inci- dent hourly average solar radiation. the maximum value of solar radiation was . w/m at : pm, while the maximum value of output power was . w at : pm. the results show that output power indicates gradually increase with increasing solar radiation intensity as shown in fig. ( ). fig. . daily hourly average pv array output power (w). a v e ra g e i n p u t p o w e r to t h e s y st e m (w /d a y ) day time (hr) h o u rl y a v e ra g e o u tp o t p o w e r( w ) s o la r r a d ia ti o n ( w /m ) day time solar radiation (w/m ) pv array output power (w) arab univ. j. agric. sci., ( ), swidan and mostafa fig. . daily measured output power as a function of average solar radiation intensity. radiation intensity also, the relationship between pv output power and solar radiation was obtained in the following equation: y = . x – . where: y= pv output power (w) and x= solar radiation (w/m ) electric power consumption measurements show increase of daily hourly average electric power consumption as a result of the increase of solar radiation as shown in fig. ( ). the highest average power consumption value was found w which represent the maximum power consumption recorded for the pumping sys- tem at : pm where the average solar radiation found to be w/m². results also show that the increase of daily hourly average electric power consumption as a result of the increase of pv power output. the highest average power consumption value was found w which represent the maximum power consumption recorded for the pumping system at : pm where the average pv output found to be w as shown in fig. ( ). fig. . hourly average electric power consumption and hourly average solar radiation levels at different day times. y = . x - . r² = . p v o u tp u t p o w e r (w ) solar radiation (w/m ) avrage array output power e le ct ri c p o w e r co n su m p ti o n ( w ) s o la r r a d ia ti o n ( w /m ) day time solar radiation (w/m ) electric power consumption (w) performance evaluation of solar photovoltaic pump for operating of landscape system arab univ. j. agric. sci., ( ), fig. . hourly average electric power consumption and hourly average output power at different day times. the hydraulic power output the results show that the pumping rate indicate gradually increase with increasing the solar radia- tion intensity as shown in fig. ( ). also, the relationship between average output flow rate and average solar radiation was obtained in as following: y = . x + . where: y= hourly average output flow rate (l/hr.) at m head and x= hourly average solar radi- ation. test results shown in fig. ( ) and fig. ( ) in- dicate that the relation of hourly average pumping rates to the hourly average solar radiation (w/m²) and relevant pv output power (w). the results show that water de- livery by the pump ranged from to l/hr. at m head depending on solar radia- tion level. the average solar radiation dur- ing the test period was w/m², while the average water delivery was l/hr. the hydraulic power output of the pump (ph) is the power required to lift a volume of water through a given head. fig. . pumping rate as a function of solar radiation. a v ra g e p o w e r co n su m p ti o n ( w ) a v a ra g e p v o u tp u t p o w e r (w ) day time (hr) pv array output power (w) electric power consumption (w) y = . x + . r² = . h o u rl y a ve ra g e o u tp o t fl o w r a te (l /h r. ) a t m h e a d hourly average solar radiation (w/m ) average pumping rate (l/hr.) linear (average pumping rate (l/hr.)) arab univ. j. agric. sci., ( ), swidan and mostafa fig. . the variation of radiation intensity caused variation in the measured output pumping rates. fig. . the variation of radiation intensity and relevant variation in the measured output pumping rates. array efficiency results show the gradually increase with in- creasing solar radiation intensity. array efficiency average values were ranged between . % at : am and . % at : pm the recorded values are in the range of w/m at the evening and at : am. fig. ( ) shows array efficiency averages at different values of solar radiation intensity. the relationship between array efficiency and solar radiation was obtained in as following: y = * - x + . where: y= array efficiency and x= solar radiation (w/m ). subsystem efficiency subsystem efficiency (ηs) was calculated con- sidering the input power is the closed circuit power of the system. pumping system efficiency was measured by calculating electric power consump- tion and hydraulic power. fig. ( ) shows that pumping system efficiency average at different values of solar radiation intensity. a v e ra g e p u m p in g r a te s ( l/ h r) a t m h e a d s o la r r a d ia ti o n ( w /m ) day time (hr) solar radiation (w/m ) average pumping rate (l/hr.) h y d ra u li c p o w e r o u tp u t (w ) a v a ra g e p v o u tp u t p o w e r (w ) day time (hr) pv array output power (w) hydraulic power output (w) performance evaluation of solar photovoltaic pump for operating of landscape system arab univ. j. agric. sci., ( ), fig. array efficiency averages at different values of solar radiation intensity. fig. shows pumping system efficiency average at deferent values of solar radiation intensity. the results show that increase of the solar ra- diation duo to the decrease the subsystem effi- ciency. the relationship between array efficiency and solar radiation was obtained in as following: y = - * - + . where: y= pumping system efficiency and x= solar radiation (w/m ). overall efficiency fig. ( ) shows the overall average efficiency of the system at different average solar radiation levels. the results show that the increase in the solar radiation duo to decrease the overall efficien- cy. summary and conclusion solar radiation intensity variation during the day time influenced the output pv power that which affects the output hydraulic power and pumping rates relatively and the generated output electric power increases with increasing solar radiation intensity, ditto for the output hydraulic power. the highest solar radiation intensity was obtained at mid-day and when the solar radiation increase, the subsystem efficiency decreases. performance of the solar photovoltaic pumping system found to be increased with increasing solar radiation intensity. it’s highly recommended to use solar photovoltaic pumping system for small landscapes for the re- mote areas out of the grid and for the growing countries to reduce the burden on national subsidi- zation for energy sources. y = e- x + . r² = . % % % % % % % a rr a y e ff ic ie n cy ; % solar radiation (w/m ) array efficiency; % linear (array efficiency; %) y = - e- x + . r² = . % % % % % % % % % % % p u m p in g s y st e m e ff ic ie n cy ; % solar radiation (w/m ) pumping system efficiency; % linear (pumping system efficiency; %) arab univ. j. agric. sci., ( ), swidan and mostafa fig. . overall average efficiency of the system at different average solar radiation levels. as an economic and environmental wise. also, it’s recommended to depend on the renewable ener- gies and of course the solar energy particularly as an alternative for fossil fuels. selection of system components plays a big role in the overall efficien- cy maximization. by selecting the matched system components, a high performance with maximum efficiency can be made. in this respect a solar pumping systems were field tested in order to evaluate its performance under local working conditions. the system comprised of three stages: first stage: generating dc power from pv cells. second stage: converting dc power into me- chanical power using dc motor. third stage: converting mechanical power into hydraulic power using centrifugal pump. the photovoltaic system was implemented consists of four modules w each, manufacturer aleo, model p polycrystalline. panels were connected in parallel to give a . a and . v total to generate power for running dc motor pump system. measuring instruments were used to obtain da- ta of the following parameters:  the output voltage and current from the photovoltaic panels by digital electrical multimeter;  water flow rate from the pump by electronic flow meter;  water pressure from the pump by analog pressure gage; the results showed that the maximum hydrau- lic output power was w where the electrical power consumption was w and the pv output power was w at solar radiation intensity of w/m². the maximum efficiency recorded for the overall system was . % where the photovoltaic generator and pumping system efficiencies were . % and . % respectively. references . carrasco, j.m., franquelo, l.g., bialasiewicz, j.t., gal-van, e., guisado, r.c.p., prats, m.a.m., leon, j.i. and moreno-alfonso, n. . power-electronic systems for thegrid in- tegration of renewable energy sources: a sur- vey. ieee transactions on industrial elec- tronics, ( ), - . gawdat. b., . egypt’s energy outlook: oppor- tunities and challenges, mediterranean quar- terly, , ( ), - . ghoneim a.a. . design optimization of pho- tovoltaic powered water pumping systems. en- ergy convers manag, , – . hamza, a. a. and taha, a. z. . performance of submersible pv solar pumping systems un- der conditions in the sudan. renewable ener- gy, ( ), - .‏ hsieh j.s. . solar energy engineering. new jersey, prantice hall. pp. - . kaldellis, j. k., meidanis, e. and zafirakis, d. . experimental energy analysis of a stand- y = - e- x + . r² = . . % . % . % . % . % . % o ve ra ll e ff ic ie n cy ; % solar radiation (w/m ) overall 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h., paykoc, e., and yener, y. . so- lar energy utilization: fundamentals and ap- plications. springer science & business media. , - . c page.indd t h e i n t e r n a t i o n a l j o u r n a l o f b u s i n e s s h i s t o r y m a r c h •• v o l u m e •• n u m b e r i s s n - •• o n l i n e i s s n - p u b l i s h e d i n a s s o c i at i o n w i t h t h e b u s i n e s s h i s t o r y c o n f e r e n c e https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core editor andrew popp, copenhagen business school associate editors shane hamilton, university of york per hansen, copenhagen business school andrea lluch, national scientifi c and technical research council sharon ann murphy, providence college associate editor for reviews alex beasley, institute for advanced study managing editor carol ressler lockman, hagley museum and library associate editor, ex officio roger horowitz, hagley museum and library editorial board xavier hernando duran amorocho (universidad de los andes) gerben bakker (london school of economics) edward j. balleisen (duke university) maria ines barbero (university of buenos aires) bernardo batiz-lazo (bangor university, uk) hartmut berghoff (georg-august- universität göttingen) christy ford chapin (university of maryland baltimore county) peter coclanis (university of north carolina-chapel hill) paul duguid (university of california, berkeley) paloma fernandez-perez (university of barcelona) patrick fridenson (École des hautes Études en sciences sociales) louis galambos (johns hopkins university) tiffany gill (university of delaware) barbara hahn (texas tech university) william hausman (college of william and mary) kris inwood (university of guelph) richard john (columbia university) geoffrey jones (harvard business school) matthias kipping (york university) takafumi kurosawa (kyoto university) pamela laird (university of colorado denver) claire lemercier (cnrs) margaret levenstein (university of michigan) kenneth lipartito (florida international university) manuel llorca-jana (university of santiago, chile) teresa da silva lopes (university of york) christopher mckenna (university of oxford) stephen mihm (university of georgia) paul miranti (rutgers university) rowena olegario (saïd business school, university of oxford) mary o’sullivan (université de genève) caitlin rosenthal (university of california, berkeley) andrea schneider (gesellschaft für unternehmensgeschichte) philip scranton (rutgers university) grietjie verhoef (university of johannesburg) mira wilkins (florida international university) joanne yates (massachusetts institute of technology) mary yeager (university of california-los angeles) madeleine zelin (columbia university) https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core enterprise & society the international journal of business history published by cambridge university press for the business history conference volume , number march introduction introduction andrew popp articles energizing finance: the energy crisis, oil futures, and neoliberal narratives caleb wellum reorganization of multinational companies in the western european chemical industry: transformations in industrial management and labor, s to s christian marx trends in the fashion business: spain and italy in comparison, – veronica binda and elisabetta merlo who tells your story: contested history at the nam jennifer delton western debates about chinese entrepreneurship in the treaty port period, – miriam kaminishi and andrew david smith black power in the boardroom: corporate america, the sullivan principles, and the anti-apartheid struggle jessica ann levy the insurance of mass murder: the development of slave life insurance policies of dutch private slave ships, – karin lurvink an incomplete revolution: corporate governance challenges of the london assurance company and the limitations of the joint-stock form, – michael aldous and stefano condorelli reviews marc flandreau. anthropologists in the stock exchange: a financial history of victorian science reviewed by david chambers sophia z. lee. the workplace constitution from the new deal to the new right reviewed by charles romney https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core noam maggor. brahmin capitalism: frontiers of wealth and populism in america’s first gilded age reviewed by daniel amsterdam brett sheehan. industrial eden: a chinese capitalist vision reviewed by Åsa malmström rognes laura phillips sawyer. american fair trade: proprietary capitalism, corporatism, and the “new competition,” – reviewed by jesse tarbert justin v. hastings. a most enterprising country: north korea in the global economy reviewed by patrick chung roger horowitz. kosher usa: how coke became kosher and other tales of modern food reviewed by derek hoff francesca russello ammon. bulldozer: demolition and clearance of the postwar landscape reviewed by morris speller marc levinson. an extraordinary time: the end of the postwar book and the return of the ordinary economy reviewed by eli cook nancy h. kwak. a world of homeowners: american power and the politics of housing aid reviewed by todd m. michney chloe e. taft. from steel to slots: casino 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/downsamplegrayimages true /grayimagedownsampletype /bicubic /grayimageresolution /grayimagedepth - /grayimagemindownsampledepth /grayimagedownsamplethreshold . /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /grayimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /jpeg grayacsimagedict << /tilewidth /tileheight /quality >> /jpeg grayimagedict << /tilewidth /tileheight /quality >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution /monoimageminresolutionpolicy /ok /downsamplemonoimages true /monoimagedownsampletype /bicubic /monoimageresolution /monoimagedepth - /monoimagedownsamplethreshold . /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k - >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx acheck false /pdfx check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ . . . . ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ . . . . ] /pdfxoutputintentprofile (none) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname () /pdfxtrapped /false /description << /chs <feff f f fd e b bbe b a b efa f e e ad d cf d a ef ee f f f c f e ee ca f ad c f b efa > /cht <feff f f e b a d f e efa acb f ef bc ad c cea d a ef ee f f f c f e ee ca f ad c f b f df efa acb ef > /dan <feff e c c e e c f f d f b d e c e c d b e e f a b c e f d f b d e b e e e f c c f e f e e> /deu <feff e e e c c e e a d c c e f e f d f b d e e c f e e e f d b a e d f e e c c d f b d e b f e e e d f e f e f f f e e e> /esp <feff c f e f e f d e f f f d f e d f c c c e e f d e f f f e f c f e f e f f e> /fra <feff c a f f e e e f d e f f e c e d f e e e c f d e e e e ea f e f c e f e f e c e e> /ita <feff c a a d f a f e f d e f f e d c c e e f d e f f e f f e f f e f e e> /jpn <feff ad c cea a d ea d ec b fa b f f e f c b f f e e a d b a f c c f d a a eb f f a f e ee d b f c d e e a d b a b f d a f c e cb fbc f c fc > /kor <feffc c c c c acc a d c ec ace d c c c dcd d c c c c d ac c a c d d c f bb c cb c c c d b c b e e c b ac c c c b c bb c cb f bc f f e c c c c d c c c f c c c b b c b e e> /nld (gebruik deze instellingen om adobe pdf-documenten te maken die zijn geoptimaliseerd voor prepress-afdrukken van hoge kwaliteit. de gemaakte pdf-documenten kunnen worden geopend met acrobat en adobe reader . en hoger.) /nor <feff b e e c c e e c e f f d f b d e f d e f f b b b f b c e d f b d e e b e e e f c c f e c c e e> /ptb <feff c a f e e f f d f d e f f d f e d d f c c e f f d e f f f d f f d f f f f e f f f e> /suo <feff b e e e e e b c b e c f c e e e e e e b e c d c f f e f f d f b d e a e c f d f b d e f e f c c a f e a c c a d d c c e> /sve <feff e e e e e e c c e e e f d c c b f d f b d e f d e c e d c f d b d f b c e b d f b d e b e f e f f f e f e e> /enu (use these settings to create adobe pdf documents best suited for high-quality prepress printing. created pdf documents can be opened with acrobat and adobe reader . and later.) >> /namespace [ (adobe) (common) ( . ) ] /othernamespaces [ << /asreaderspreads false /cropimagestoframes true /errorcontrol /warnandcontinue /flattenerignorespreadoverrides false /includeguidesgrids false /includenonprinting false /includeslug false /namespace [ (adobe) (indesign) ( . ) ] /omitplacedbitmaps false /omitplacedeps false /omitplacedpdf false /simulateoverprint /legacy >> << /addbleedmarks false /addcolorbars false /addcropmarks false /addpageinfo false /addregmarks false /convertcolors /converttocmyk /destinationprofilename () /destinationprofileselector /documentcmyk /downsample bitimages true /flattenerpreset << /presetselector /mediumresolution >> /formelements false /generatestructure false /includebookmarks false /includehyperlinks false /includeinteractive false /includelayers false /includeprofiles false /multimediahandling /useobjectsettings /namespace [ (adobe) (creativesuite) ( . ) ] /pdfxoutputintentprofileselector /documentcmyk /preserveediting true /untaggedcmykhandling /leaveuntagged /untaggedrgbhandling /usedocumentprofile /usedocumentbleed false >> ] >> setdistillerparams << /hwresolution [ ] /pagesize [ . . ] >> setpagedevice << /ascii encodepages false /allowtransparency false /autopositionepsfiles false /autorotatepages /none /binding /left /calgrayprofile (dot gain %) /calrgbprofile (srgb iec - . ) /calcmykprofile (u.s. web coated \ swop\ v ) /srgbprofile (srgb iec - . ) /cannotembedfontpolicy /error /compatibilitylevel . /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves . /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel /emitdscwarnings false /endpage - /imagememory /lockdistillerparams true /maxsubsetpct /optimize false /opm /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage false /preservedicmykvalues true /preserveepsinfo false /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage /subsetfonts true /transferfunctioninfo /remove /ucrandbginfo /remove /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution /colorimageminresolutionpolicy /ok /downsamplecolorimages true /colorimagedownsampletype /bicubic /colorimageresolution /colorimagedepth - /colorimagemindownsampledepth /colorimagedownsamplethreshold . /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /colorimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /jpeg coloracsimagedict << /tilewidth /tileheight /quality >> /jpeg colorimagedict << /tilewidth /tileheight /quality >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution /grayimageminresolutionpolicy /ok /downsamplegrayimages true /grayimagedownsampletype /bicubic /grayimageresolution /grayimagedepth - /grayimagemindownsampledepth /grayimagedownsamplethreshold . /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /grayimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /jpeg grayacsimagedict << /tilewidth /tileheight /quality >> /jpeg grayimagedict << /tilewidth /tileheight /quality >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution /monoimageminresolutionpolicy /ok /downsamplemonoimages true /monoimagedownsampletype /bicubic /monoimageresolution /monoimagedepth - /monoimagedownsamplethreshold . /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k - >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx acheck false /pdfx check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ . . . . ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ . . . . ] /pdfxoutputintentprofile (none) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname () /pdfxtrapped /false /description << /chs <feff f f fd e b bbe b a b efa f e e ad d cf d a ef ee f f f c f e ee ca f ad c f b efa > /cht <feff f f e b a d f e efa acb f ef bc ad c cea d a ef ee f f f c f e ee ca f ad c f b f df efa acb ef > /dan <feff e c c e e c f f d f b d e c e c d b e e f a b c e f d f b d e b e e e f c c f e f e e> /deu <feff e e e c c e e a d c c e f e f d f b d e e c f e e e f d b a e d f e e c c d f b d e b f e e e d f e f e f f f e e e> /esp <feff c f e f e f d e f f f d f e d f c c c e e f d e f f f e f c f e f e f f e> /fra <feff c a f f e e e f d e f f e c e d f e e e c f d e e e e ea f e f c e f e f e c e e> /ita <feff c a a d f a f e f d e f f e d c c e e f d e f f e f f e f f e f e e> /jpn <feff ad c cea a d ea d ec b fa b f f e f c b f f e e a d b a f c c f d a a eb f f a f e ee d b f c d e e a d b a b f d a f c e cb fbc f c fc > /kor <feffc c c c c acc a d c ec ace d c c c dcd d c c c c d ac c a c d d c f bb c cb c c c d b c b e e c b ac c c c b c bb c cb f bc f f e c c c c d c c c f c c c b b c b e e> /nld (gebruik deze instellingen om adobe pdf-documenten te maken die zijn geoptimaliseerd voor prepress-afdrukken van hoge kwaliteit. de gemaakte pdf-documenten kunnen worden geopend met acrobat en adobe reader . en hoger.) /nor <feff b e e c c e e c e f f d f b d e f d e f f b b b f b c e d f b d e e b e e e f c c f e c c e e> /ptb <feff c a f e e f f d f d e f f d f e d d f c c e f f d e f f f d f f d f f f f e f f f e> /suo <feff b e e e e e b c b e c f c e e e e e e b e c d c f f e f f d f b d e a e c f d f b d e f e f c c a f e a c c a d d c c e> /sve <feff e e e e e e c c e e e f d c c b f d f b d e f d e c e d c f d b d f b c e b d f b d e b e f e f f f e f e e> /enu (use these settings to create adobe pdf documents best suited for high-quality prepress printing. created pdf documents can be opened with acrobat and adobe reader . and later.) >> /namespace [ (adobe) (common) ( . ) ] /othernamespaces [ << /asreaderspreads false /cropimagestoframes true /errorcontrol /warnandcontinue /flattenerignorespreadoverrides false /includeguidesgrids false /includenonprinting false /includeslug false /namespace [ (adobe) (indesign) ( . ) ] /omitplacedbitmaps false /omitplacedeps false /omitplacedpdf false /simulateoverprint /legacy >> << /addbleedmarks false /addcolorbars false /addcropmarks false /addpageinfo false /addregmarks false /convertcolors /converttocmyk /destinationprofilename () /destinationprofileselector /documentcmyk /downsample bitimages true /flattenerpreset << /presetselector /mediumresolution >> /formelements false /generatestructure false /includebookmarks false /includehyperlinks false /includeinteractive false /includelayers false /includeprofiles false /multimediahandling /useobjectsettings /namespace [ (adobe) (creativesuite) ( . ) ] /pdfxoutputintentprofileselector /documentcmyk /preserveediting true /untaggedcmykhandling /leaveuntagged /untaggedrgbhandling /usedocumentprofile /usedocumentbleed false >> ] >> setdistillerparams << /hwresolution [ ] /pagesize [ . . ] >> setpagedevice << /ascii encodepages false /allowtransparency false /autopositionepsfiles false /autorotatepages /none /binding /left /calgrayprofile (dot gain %) /calrgbprofile (srgb iec - . ) /calcmykprofile (u.s. web coated \ swop\ v ) /srgbprofile (srgb iec - . ) /cannotembedfontpolicy /error /compatibilitylevel . /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves . /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel /emitdscwarnings false /endpage - /imagememory /lockdistillerparams true /maxsubsetpct /optimize false /opm /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage false /preservedicmykvalues true /preserveepsinfo false /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage /subsetfonts true /transferfunctioninfo /remove /ucrandbginfo /remove /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution /colorimageminresolutionpolicy /ok /downsamplecolorimages true /colorimagedownsampletype /bicubic /colorimageresolution /colorimagedepth - /colorimagemindownsampledepth /colorimagedownsamplethreshold . /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /colorimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /jpeg coloracsimagedict << /tilewidth /tileheight /quality >> /jpeg colorimagedict << /tilewidth /tileheight /quality >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution /grayimageminresolutionpolicy /ok /downsamplegrayimages true /grayimagedownsampletype /bicubic /grayimageresolution /grayimagedepth - /grayimagemindownsampledepth /grayimagedownsamplethreshold . /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /grayimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /jpeg grayacsimagedict << /tilewidth /tileheight /quality >> /jpeg grayimagedict << /tilewidth /tileheight /quality >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution /monoimageminresolutionpolicy /ok /downsamplemonoimages true /monoimagedownsampletype /bicubic /monoimageresolution /monoimagedepth - /monoimagedownsamplethreshold . /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k - >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx acheck false /pdfx check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ . . . . ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ . . . . ] /pdfxoutputintentprofile (none) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname () /pdfxtrapped /false /description << /chs <feff f f fd e b bbe b a b efa f e e ad d cf d a ef ee f f f c f e ee ca f ad c f b efa > /cht <feff f f e b a d f e efa acb f ef bc ad c cea d a ef ee f f f c f e ee ca f ad c f b f df efa acb ef > /dan <feff e c c e e c f f d f b d e c e c d b e e f a b c e f d f b d e b e e e f c c f e f e e> /deu <feff e e e c c e e a d c c e f e f d f b d e e c f e e e f d b a e d f e e c c d f b d e b f e e e d f e f e f f f e e e> /esp <feff c f e f e f d e f f f d f e d f c c c e e f d e f f f e f c f e f e f f e> /fra <feff c a f f e e e f d e f f e c e d f e e e c f d e e e e ea f e f c e f e f e c e e> /ita <feff c a a d f a f e f d e f f e d c c e e f d e f f e f f e f f e f e e> /jpn <feff ad c cea a d ea d ec b fa b f f e f c b f f e e a d b a f c c f d a a eb f f a f e ee d b f c d e e a d b a b f d a f c e cb fbc f c fc > /kor <feffc c c c c acc a d c ec ace d c c c dcd d c c c c d ac c a c d d c f bb c cb c c c d b c b e e c b ac c c c b c bb c cb f bc f f e c c c c d c c c f c c c b b c b e e> /nld (gebruik deze instellingen om adobe pdf-documenten te maken die zijn geoptimaliseerd voor prepress-afdrukken van hoge kwaliteit. de gemaakte pdf-documenten kunnen worden geopend met acrobat en adobe reader . en hoger.) /nor <feff b e e c c e e c e f f d f b d e f d e f f b b b f b c e d f b d e e b e e e f c c f e c c e e> /ptb <feff c a f e e f f d f d e f f d f e d d f c c e f f d e f f f d f f d f f f f e f f f e> /suo <feff b e e e e e b c b e c f c e e e e e e b e c d c f f e f f d f b d e a e c f d f b d e f e f c c a f e a c c a d d c c e> /sve <feff e e e e e e c c e e e f d c c b f d f b d e f d e c e d c f d b d f b c e b d f b d e b e f e f f f e f e e> /enu (use these settings to create adobe pdf documents best suited for high-quality prepress printing. created pdf documents can be opened with acrobat and adobe reader . and later.) >> /namespace [ (adobe) (common) ( . ) ] /othernamespaces [ << /asreaderspreads false /cropimagestoframes true /errorcontrol /warnandcontinue /flattenerignorespreadoverrides false /includeguidesgrids false /includenonprinting false /includeslug false /namespace [ (adobe) (indesign) ( . ) ] /omitplacedbitmaps false /omitplacedeps false /omitplacedpdf false /simulateoverprint /legacy >> << /addbleedmarks false /addcolorbars false /addcropmarks false /addpageinfo false /addregmarks false /convertcolors /converttocmyk /destinationprofilename () /destinationprofileselector /documentcmyk /downsample bitimages true /flattenerpreset << /presetselector /mediumresolution >> /formelements false /generatestructure false /includebookmarks false /includehyperlinks false /includeinteractive false /includelayers false /includeprofiles false /multimediahandling /useobjectsettings /namespace [ (adobe) (creativesuite) ( . ) ] /pdfxoutputintentprofileselector /documentcmyk /preserveediting true /untaggedcmykhandling /leaveuntagged /untaggedrgbhandling /usedocumentprofile /usedocumentbleed false >> ] >> setdistillerparams << /hwresolution [ ] /pagesize [ . . ] >> setpagedevice << /ascii encodepages false /allowtransparency false /autopositionepsfiles false /autorotatepages /none /binding /left /calgrayprofile (dot gain %) /calrgbprofile (srgb iec - . ) /calcmykprofile (u.s. web coated \ swop\ v ) /srgbprofile (srgb iec - . ) /cannotembedfontpolicy /error /compatibilitylevel . /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves . /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel /emitdscwarnings false /endpage - /imagememory /lockdistillerparams true /maxsubsetpct /optimize false /opm /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage false /preservedicmykvalues true /preserveepsinfo false /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage /subsetfonts true /transferfunctioninfo /remove /ucrandbginfo /remove /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution /colorimageminresolutionpolicy /ok /downsamplecolorimages true /colorimagedownsampletype /bicubic /colorimageresolution /colorimagedepth - /colorimagemindownsampledepth /colorimagedownsamplethreshold . /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /colorimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /jpeg coloracsimagedict << /tilewidth /tileheight /quality >> /jpeg colorimagedict << /tilewidth /tileheight /quality >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution /grayimageminresolutionpolicy /ok /downsamplegrayimages true /grayimagedownsampletype /bicubic /grayimageresolution /grayimagedepth - /grayimagemindownsampledepth /grayimagedownsamplethreshold . /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /grayimagedict << /qfactor . /hsamples [ ] /vsamples [ ] >> /jpeg grayacsimagedict << /tilewidth /tileheight /quality >> /jpeg grayimagedict << /tilewidth /tileheight /quality >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution /monoimageminresolutionpolicy /ok /downsamplemonoimages true /monoimagedownsampletype /bicubic /monoimageresolution /monoimagedepth - /monoimagedownsamplethreshold . /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k - >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx acheck false /pdfx check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ . . . . ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ . . . . ] /pdfxoutputintentprofile (none) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname () /pdfxtrapped /false /description << /chs <feff f f fd e b bbe b a b efa f e e ad d cf d a ef ee f f f c f e ee ca f ad c f b efa > /cht <feff f f e b a d f e efa acb f ef bc ad c cea d a ef ee f f f c f e ee ca f ad c f b f df efa acb ef > /dan <feff e c c e e c f f d f b d e c e c d b e e f a b c e f d f b d e b e e e f c c f e f e e> /deu <feff e e e c c e e a d c c e f e f d f b d e e c f e e e f d b a e d f e e c c d f b d e b f e e e d f e f e f f f e e e> /esp <feff c f e f e f d e f f f d f e d f c c c e e f d e f f f e f c f e f e f f e> /fra <feff c a f f e e e f d e f f e c e d f e e e c f d e e e e ea f e f c e f e f e c e e> /ita <feff c a a d f a f e f d e f f e d c c e e f d e f f e f f e f f e f e e> /jpn <feff ad c cea a d ea d ec b fa b f f e f c b f f e e a d b a f c c f d a a eb f f a f e ee d b f c d e e a d b a b f d a f c e cb fbc f c fc > /kor <feffc c c c c acc a d c ec ace d c c c dcd d c c c c d ac c a c d d c f bb c cb c c c d b c b e e c b ac c c c b c bb c cb f bc f f e c c c c d c c c f c c c b b c b e e> /nld (gebruik deze instellingen om adobe pdf-documenten te maken die zijn geoptimaliseerd voor prepress-afdrukken van hoge kwaliteit. de gemaakte pdf-documenten kunnen worden geopend met acrobat en adobe reader . en hoger.) /nor <feff b e e c c e e c e f f d f b d e f d e f f b b b f b c e d f b d e e b e e e f c c f e c c e e> /ptb <feff c a f e e f f d f d e f f d f e d d f c c e f f d e f f f d f f d f f f f e f f f e> /suo <feff b e e e e e b c b e c f c e e e e e e b e c d c f f e f f d f b d e a e c f d f b d e f e f c c a f e a c c a d d c c e> /sve <feff e e e e e e c c e e e f d c c b f d f b d e f d e c e d c f d b d f b c e b d f b d e b e f e f f f e f e e> /enu (use these settings to create adobe pdf documents best suited for high-quality prepress printing. created pdf documents can be opened with acrobat and adobe reader . and later.) >> /namespace [ (adobe) (common) ( . ) ] /othernamespaces [ << 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carbon concentration and oxygen availability affect lipid and carotenoid production by carob pulp syrup&#x ;grown <i>rhodosporidium toruloides</i> ncyc eng. life sci. , , – www.els-journal.com teresa margarida parreira claudia freitas alberto reis josé roseiro teresa lopes da silva unidade de bioenergia, laboratório nacional de energia e geologia, lisboa, portugal research article carbon concentration and oxygen availability affect lipid and carotenoid production by carob pulp syrup-grown rhodosporidium toruloides ncyc the simultaneous effect of oxygen availability and carbon source concentration on yeast lipid and carotenoid production has never been studied before. in this work, a doehlert distribution design was used to study the simultaneous effect of carbon concentration and oxygen availability on rhodosporidium toruloides ncyc carotenoid and lipid production. a cheap industrial byproduct was used as carbon source (carob pulp syrup). a total sugar concentration of . g/l and a medium volume of . l induced the highest total carotenoid and total fatty acid productivities ( . μg/lh and . g/lh, respectively). flow cytometry was used to assess yeast stress response under different cultivation conditions. the highest proportion of cells with permeabilised membrane (> %) was induced when the cultivations were carried out at the highest sugar concentration studied ( . g/l) or when the culture reached the minimum final medium ph ( . ). the results showed that the total sugar concentration had a positive influence on the yeast biomass and carotenoid content, while the oxygen availability had little influence on the biomass concentration, but had a slight positive influence on the carotenoid content. regarding the fatty acids, the two factors had a negative impact on the synthesis of these compounds. keywords: carbon concentration / carotenoids / lipids / oxygen availability / yeast � additional supporting information may be found in the online version of this article atthe publisher’s web-site received: january , ; revised: march , ; accepted: may , doi: . /elsc. introduction in the midst of the energy crisis, third generation biofuels (de- rived from microalgae and other microbes) are considered to be viable fuel alternatives [ , ]. however, to be economically sustainable, the microbial biofuel production process must val- orize the whole biomass fractions to be converted into biofuels and high value added products under the frame of an integrated biorefinery concept. correspondence: dr. teresa lopes da silva (teresa.lopessilva@ lneg.pt), unidade de bioenergia, laboratório nacional de energia e geologia, i.p., estrada do paço do lumiar , - lisboa, portugal abbreviations: dioc ( ), , -dihexylocarbocyanine iodide; mufas, monounsaturated fatty acids; pi, propidium iodide; pufas, polyunsat- urated fatty acids; sats, saturated fatty acids; tfas, total fatty acids the oleaginous yeast rhodosporidium toruloides ncyc (which species is an anamorph of rhodotorula glutinis species) has been widely reported as a potential oil producer yeast [ , ]. however, the yeast biomass, beyond its high lipid content (that can be converted into biodiesel), is rich in high value added products such carotenoids with commercial interest [ ] their commercialization may contribute to reduce the overall process cost of biofuels and carotenoid production [ ]. the use of low-cost substrates in media formulations may also reduce the costs of the microbial biofuels production [ ]. carob pulp syrup has been used in media formulations for micro- bial lipid production [ ]. the carob tree (ceratonia siliqua l.) is native to the mediterranean region, including southern eu- ropean countries. carob seeds comprise % of the fruit dry weight and are used for gum production for food industry. the remaining % of the fruit dry weight (the pulp) contains high content of sugar (sucrose, glucose and fructose). the easily c© wiley-vch verlag gmbh & co. kgaa, weinheim 	parreira et al [pdf] cerebral glutamine and glutamate levels in relation to compromised energy metabolism: a microdialysis study in subarachnoid hemorrhage patients | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /sj.jcbfm. corpus id: cerebral glutamine and glutamate levels in relation to compromised energy metabolism: a microdialysis study in subarachnoid hemorrhage patients @article{samuelsson cerebralga, title={cerebral glutamine and glutamate levels in relation to compromised energy metabolism: a microdialysis study in subarachnoid hemorrhage patients}, author={c. samuelsson and l. hillered and m. zetterling and p. enblad and g. hesselager and m. ryttlefors and e. kumlien and a. lew{\'e}n and n. marklund and p. nilsson and k. salci and e. ronne-engstr{\"o}m}, journal={journal of cerebral blood flow & metabolism}, year={ }, volume={ }, pages={ - } } 	c. samuelsson, l. hillered, + authors e. ronne-engström 	published 	medicine 	journal of cerebral blood flow & metabolism astrocytic glutamate (glt) uptake keeps brain interstitial glt levels low. within the astrocytes glt is converted to glutamine (gln), which is released and reconverted to glt in neurons. the glt–gln cycle is energy demanding and impaired energy metabolism has been suggested to cause low interstitial gln/glt ratios. using microdialysis (md) measurements from visually noninjured cortex in neurointensive care patients with subarachnoid hemorrhage, we have determined how interstitial glt and gln… expand view on sage journals.sagepub.com save to library create alert cite launch research feed share this paper citationshighly influential citations background citations results citations view all figures, tables, and topics from this paper 	 table 	 figure 	 figure 	 figure 	 figure 	 figure view all figures & tables 	glutamic acid 	glutamine 	subarachnoid hemorrhage 	microdialysis 	pyruvates 	lactic acid 	ischemia 	energy metabolism 	cerebral infarction 	idiopathic pulmonary fibrosis 	moderate response citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency relationship between intracranial hemodynamics and microdialysis markers of energy metabolism and glutamate-glutamine turnover in patients with subarachnoid hemorrhage. clinical article. 	c. samuelsson, t. howells, e. kumlien, p. enblad, l. hillered, e. ronne-engström 	medicine 	journal of neurosurgery 	 	 	pdf save alert research feed systemic glucose and brain energy metabolism after subarachnoid hemorrhage 	r. helbok, j. schmidt, + authors j. claassen 	medicine 	neurocritical care 	 	 	view excerpt, cites background save alert research feed temporal patterns of interstitial pyruvate and amino acids after subarachnoid haemorrhage are related to the level of consciousness—a clinical microdialysis study 	m. zetterling, l. hillered, c. samuelsson, t. karlsson, p. enblad, e. ronne-engström 	medicine 	acta neurochirurgica 	 	 	view excerpts, cites background and results save alert research feed microdialysis patterns in subarachnoid hemorrhage patients with focus on ischemic events and brain interstitial glutamine levels 	c. samuelsson, l. hillered, p. enblad, e. ronne-engström 	medicine 	acta neurochirurgica 	 	 	view excerpts, cites background save alert research feed relation between brain interstitial and systemic glucose concentrations after subarachnoid hemorrhage. 	m. zetterling, l. hillered, p. enblad, t. karlsson, e. ronne-engström 	medicine 	journal of neurosurgery 	 	 save alert research feed brain lactate metabolism in humans with subarachnoid hemorrhage 	m. oddo, j. levine, + authors p. leroux 	medicine 	stroke 	 	 	pdf save alert research feed cerebral metabolic changes related to oxidative metabolism in a model of bacterial meningitis induced by lipopolysaccharide 	m. munk, f. poulsen, l. larsen, c. nordström, t. nielsen 	medicine 	neurocritical care 	 	 	view excerpt, cites background save alert research feed brain energy metabolism in patients with spontaneous subarachnoid hemorrhage and global cerebral edema 	m. zetterling, l. hallberg, l. hillered, t. karlsson, p. enblad, elisabeth ronne engström 	medicine 	neurosurgery 	 	 save alert research feed cerebral extracellular lactate increase is predominantly nonischemic in patients with severe traumatic brain injury 	n. sala, t. suys, + authors m. oddo 	medicine 	journal of cerebral blood flow and metabolism : official journal of the international society of cerebral blood flow and metabolism 	 	 	 save alert research feed the human brain utilizes lactate via the tricarboxylic acid cycle: a c-labelled microdialysis and high-resolution nuclear magnetic resonance study. 	c. gallagher, k. carpenter, + authors p. hutchinson 	biology, medicine 	brain : a journal of neurology 	 	 	highly influenced 	pdf 	view excerpts, cites background save alert research feed ... ... references showing - of references sort byrelevance most influenced papers recency extracellular glutamine to glutamate ratio may predict outcome in the injured brain: a clinical microdialysis study in children. 	d. richards, c. tolias, s. sgouros, n. bowery 	biology, medicine 	pharmacological research 	 	 	view excerpts, references methods and background save alert research feed cerebral interstitial levels of glutamate and glutamine after intravenous administration of nutritional amino acids in neurointensive care patients 	elisabeth ronne engström, l. hillered, p. enblad, t. karlsson 	biology, medicine 	neuroscience letters 	 	 	view excerpts, references methods save alert research feed extracellular metabolites in the cortex and hippocampus of epileptic patients 	i. cavus, willard s. kasoff, + authors w. abi-saab 	biology, medicine 	annals of neurology 	 	 	view excerpt, references background save alert research feed in vivo neuroprotective adaptation of the glutamate/glutamine cycle to neuronal death 	d. ramonet, m. j. rodríguez, k. fredriksson, f. bernal, n. mahy 	chemistry, medicine 	hippocampus 	 	 	view excerpt, references background save alert research feed glutamine synthetase in brain: effect of ammonia 	i. suárez, g. bodega, b. fernández 	biology, medicine 	neurochemistry international 	 	 	view excerpt, references background save alert research feed neurochemical monitoring using intracerebral microdialysis in patients with subarachnoid hemorrhage. 	l. persson, j. valtysson, + authors l. hillered 	medicine 	journal of neurosurgery 	 	 	pdf 	view excerpts, references background and results save alert research feed quantitative determination of extracellular glutamine concentration in rat brain, and its elevation in vivo by system a transport inhibitor, α‐(methylamino)isobutyrate 	k. kanamori, b. ross 	biology, medicine 	journal of neurochemistry 	 	 	 	view excerpt, references background save alert research feed determination of the rate of the glutamate/glutamine cycle in the human brain by in vivo c nmr. 	j. shen, k. petersen, + authors d. rothman 	medicine, biology 	proceedings of the national academy of sciences of the united states of america 	 	 	pdf 	view excerpt, references background save alert research feed blood-brain barrier glutamine transport during normoglycemic and hyperglycemic focal cerebral ischemia 	n. kawai, w. stummer, s. ennis, a. betz, r. keep 	medicine 	journal of cerebral blood flow and metabolism : official journal of the international society of cerebral blood flow and metabolism 	 	 	 	view excerpt, references background save alert research feed dynamics of extracellular metabolites in the striatum after middle cerebral artery occlusion in the rat monitored by intracerebral microdialysis 	l. hillered, a. hallström, s. segersvärd, l. persson, u. ungerstedt 	biology, medicine 	journal of cerebral blood flow and metabolism : official journal of the international society of cerebral blood flow and metabolism 	 	 	 	view excerpt, references methods save alert research feed ... ... related papers 	abstract 	figures, tables, and topics 	 citations 	 references 	related papers stay connected with semantic scholar sign up about semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue trends of risk and security problems for states and emerging strategies for coping with those trends by robert ellsworth when one considers very carefully the risk and security problems that states face today, and then looks at how states are attempting to cope with those problems, one is almost forced to the old definition of strategy as: "when you have run out of bullets, how to keep on firing." introduction we live today in an "age of peace ". what does one mean by that phrase - an age of peace? it is surely something different from the condition of having recently recovered from a war, or getting ready to fight the next war, which are the conditions that most of mankind has been in for most of history. in an age of peace, on the other hand, there is no war or prospect of war, between the major powers, of the kind which the powers maintain their main forces to fight. there have been a few periods like this in recent history: after the napoleon period, there was a wide-spread determination in europe never to let anything like that happen again. after world war i, which was rhetorically "the war to end all wars ", there was a wide-spread determination not to have any more war. ages of peace don't rule out revolutions, or wars with lesser powers, but the age of peace which we have enjoyed for about years is different. it's unique in two respects: first, in the length of time it's lasted; and secondly the intensity and the wide-spread scope of the feeling that a war between the major powers, with the strategic nuclear weapons that they maintain, is absolutely unthinkable. so that we do live in a unique age of peace. and of course the first great risk for states is the risk of the collapse of that condition. another great set of risks that we face today - as states and as peoples - is the risks that come from an apparent global shortage of material resources. the energy crisis is one example. there are a number of other examples and we will examine some of them. there is a specific risk in the build-up of military forces on the part of the soviet union. not just in the strategic nuclear realm, but also in their deployments in europe, in terms of their naval build-up and deployments, in their capabilities for projecting and exercising power beyond eurasia, and in their utiisation of modern technology. there are, in a general sense, two other kinds of risks that states face today. on the one hand, there is always the risk of being taken by surprise. in military history one is familiar with the surprises that have been visited on various states: operation barba- rossa, the german invasion of russia in june ; pearl harbour, the japanese attack on the united states in december of that year; and in the middle east the israeli attack on egypt in june and the egyptian attack on the sinai in october . also in the non-military field, states were taken quite by surprise in october by the oil embargo, and during that winter by the % increase in crude oil prices suddenly imposed by opec. what happens is that states decline to look at signs which, in retrospect, are always said to have been quite visible. states decline to see what is unpleasant for them to see, and they tend to get taken by surprise. contrarywise another risk is that states in contemplating the external world tend to exaggerate certain risks and therefore make unwise, and unnecessary concessions. for example in the case of the german re-occupation in the rheinland in the western powers exaggerated the risks of response if they offered resistance to the re-occupation of the rheinland. in , risks were exaggerated with the result that the united states conceded too much in the interim agreement covering offensive nuclear weapons, in salt i. that was corrected later at vladivostok in , but there is almost always the risk of exaggerating risks, and of making unnecessary and unwise concessions, or yielding unnecessarily, as a result. oil pricing practices let us look first at some of the specific risks involved in oil pricing practices: a problem with which all states are confronted today, not just the oil-consuming industrial states. the non-oil lesser developed countries have even worse problems coping with current oil pricing practices, and in my judgment the oil-producing states themselves have certain problems associated with the pricing practices that they are pursuing today. for the last five years the lowest inflation rates in the industrial world have been well above what had been considered unacceptably high levels of inflation during the entire post world war ii era. and then, there are the particular problems imposed on the industrial countries not just by the level of inflation, which is extremely high, but also by the fact that among different countries the rates are different. within the oecd, for example, inflation rates today range between % in some countries to as high as % in other countries. that creates very great problems in trade, monetary policy, etc. unemployment is another high-risk condition which has been exacerbated by the oil pricing practices of the world today, and i need not say to this group that inflation and unemployment together have historically been the father of confrontation and upheaval and the grand-father of war. a further very great risk stems from the fact that we are entrapped in a vicious circle. whenever recovery commences in the industrial countries, that is used as a justification by the oil producing countries to increase their prices. that of course takes the edge off the recovery, reinstitutes conditions of virulent inflation and unemploy- ment and calls forth measures to cope with those undesirable and risky conditions. it doesn't work. the world does not work today under the oil pricing practices currently being followed. here is a case where i think it's fair to say the strategies of states are largely an exercise in how to keep on firing after you have run out of bullets. no one today has any strategy for dealing directly with current oil pricing practices. of course states are trying to sell goods to the oil producers to cope with balance of payments problems, taking certain modest measures of conservation, going into debt up to their eyeballs, or doing all of the above. but essentially there is no strategy today for dealing directly with oil pricing practices as such. the reason, or one of the reasons why this is so, is that economically recoverable oil exists only in limited quantities in the earth and that within a certain number of years it will be necessary to replace oil with alternative sources of energy. and in order to develop alternatives to oil as a source of energy it is necessary that oil prices be at something like their present levels. still, there is some room for the exercise of strategy in this important area. one of the partial alternatives to oil which creates some risks is nuclear energy. in / the oil embargo and price rise gave a tremendous ifilip to the development of nuclear energy in a number of states because for them there is absolutely no option other than nuclear power as a source of electricity. that created the virtual certainty within years of very large amounts of plutonium (which is a nuclear explosive) in stockpiles all over the world in spent fuel from nuclear reactors. that - coupled with the nuclear explosion of india in may - regenerated the spectre of nuclear weapons proliferation on a world-wide basis, which was not a new concern but had been quiescent for a number of years. in addition, a number of industrial countries in the early 's had begun a spirited competition in the export of nuclear technology which must increase the risks of weapons proliferation. there is now an effort by states to develop a strategy to cope; initial steps are being taken. in many cases those steps are a little bit stumbling. for example last week, on april th, president carter made a statement in washington aimed at the elimination of plutonium from the world economy. in order to induce states to forego access to plutonium, he alluded to the possibility of the united states supplying the world with enriched fuel so that the world could avoid reprocessing and the creation of free plutonium. to put it directly: president carter has asked the world, as a part of a strategy to avoid the risks of nuclear weapons proliferation, to forego access to nuclear fuel except that which might be supplied by the u.s.a. that is not a viable basis for a widely shared or a long lasting international regime. other steps will have to be taken to develop a strategy for dealing with the problem of proliferation as the world develops nuclear energy to substitute partially for oil. global resource shortages the energy crisis, based as it is on the realization that there is a limited supply of economically recoverable oil available, is only one example of what many believe is a much wider problem: the risks of broad global resource shortages. with regard to that problem there are two conflicting views. the "catastrophists" believe that the earth's resources will soon be exhausted, and the approach of this condition will lead to the collapse of society, including the end of the age of peace to which i referred at the beginning of my remarks. the conflicting view, that of the "cornucopians ", holds that most of the earth's essential raw materials are virtually infinite and that as we exhaust one raw material we will turn to inexhaustible substitutes. according to this view we will ultimately settle into a steady state of substitution and recycling of materials. in order to bring a little perspective to these two conflicting views, it is useful to realize that % of all the molecules that we take out of the earth and use are fossil fuel. all our technological civilization, and especially our transportation, is based on an addiction to fossil fuel - an addiction that cannot be broken, or at least cannot be broken in the foreseeable future. that is a very special problem. but the minerals that we depend upon - iron, aluminium, and copper - are present in very large quantities throughout the world and at high concentrations. for those elements like mercury or silver that are not so widely present there are in fact large possibilities for substitution. therefore, the energy problem is different in degree to the extent that it is a different problem in kind. it is necessary not to confuse the two. certainly there are great risks associated with both. what are the risks? the present stage of the world, while we are using up fossil fuel at a terrific rate, may be called stage i. stage iii, i see as the age of substitutability. the risks lie in developing appropriate strategies to get from stage i to stage iii. so far the strategies that have been spoken about and attempted seem to be quite unadequate. first, it takes a long time to transition just in the case of energy: it took years to transition from wood to coal, it took about the same period to transition from coal to oil and gas. as we look at strategies for transitionning from oil and gas to something else - it seems clear that rising environmental concerns, and shortages of capital, may stretch that process even further. that risk is multiplied many times by the short time horizons of most government agencies and corporations responsible for resource policy. decision-making in corpora- tions is conditioned by interest rates which encourage indifference to costs and benefits that won't be realized within about five years. inflation further shortens the time horizon. in the case of governments, the next election prevents most policies that could return great benefits over the long term, so that governments tend to have a short time horizon. totalitarian and authoritarian governments do not seem to be doing much better, so i am not certain that the answer is the abandonment of democracy. there is no model anywhere in the world of a state dealing with the problem in a way that offers much help. what are in fact the emerging strategies? first, we see competition for access to oil. chart i the possibility of there being a balance between opec's ability and willingness to provide oil to the world on the one hand, and the needs of the oecd countries for estimated opec export levels (in million barrels a day) estimated oecd import needs (in million barrels a day) policy exports assumption imports low , high growth , medium-low , medium growth , medium-high , low growth , high , accelerated policy , source: ocd, world energy outlook, source: rustow, "foreign affairs ", april , pp , , - . , p. q. oil, on the other hand, is very slight. unless we are very lucky indeed, the figures portend in fairly clear terms a major world crisis in the early or mid 's because of the fact that there may not be enough oil from opec to satisfy the needs of the oecd countries. this alarming situation assumes zero interest on the part of the soviet union in opec oil by . that is an assumption which appears to be quite optimistic inasmuch as the soviets have their energy problem too. they are experiencing rising industrial and consumer demand for energy. they have great difficulties developing their energy resources in sibiria. they have not been able to get the capital or the technology from the west. the u.s.s.r. therefore will turn more and more to the gulf and middle east for access to that low cost and easy to extract (though not low price) oil. although the opec price is something over $ . a barrel, it costs only about cents a barrel to extract. the soviets - i expect - will need oil from the gulf and middle east by to the tune of somewhere between and million barrels a day. that will cause horrendous problems for all of us: europeans, americans, japanese, and russians. competition for access, then, is one of the strategies that has begun to emerge for dealing with the energy crisis. there are also the beginnings of another strategy for dealing with the overall global resource shortage problem, and that strategy could be called the deliberate societal shift toward placing an intrinsic value on conservation, on low material and energy growth. this, perhaps, holds out considerable hope, for two reasons. first, it is only by having a set of values that one can develop a strategy: that is in fact what a strategy is. a strategy is basically a set of values that permits one to take a longer term view of matters whatever those matters are - than would be dictated by short term tactical considerations. the emergence of a set of values, therefore, is a hopeful sign. secondly major deliberate societal shifts in values of this kind can take place quickly, have done so in the past. between and in europe a rapid and pervasive social change took place as nation after nation abandoned high rates of marital fertility and adopted contraception on a wide scale. as a result, in this short -year period there was a very great reduction in the birth rate in europe as a deliberate internalisation of a set of values and therefore of a strategy. this was rather suggested not imposed by any corporation or government. we cannot predict the future, but we can have value systems - a strategy - that will help us move from stage i to stage iii. those values would be a) conservation; efficiency and effectiveness in the transformation of raw resources into food, fertilizer, electricity, and machinery, placing a premium if you will on science and technology; cooperation instead of competition; d) steadiness of purpose; e) resilience in response to change these are some of the characteristics and qualities of a viable strategy which can help us move from stage i to stage iii without having a collapse of society, a termination of the age of peace. the russian military build-up in the meanwhile however, we are confronted with the risks of a very substantial russian build-up. for the last ten years, the soviet union has been adding between % and % a year, in real terms, to the resources devoted to military purposes. in those resources exceeded the comparable resources devoted to military purposes by the united states, and have exceeded the u.s. in every year since then. in the soviets were spending, in real terms, % more on their military than the united states. as for the future effects of present spending, the u.s.s.r. has been spending on investment account - that is to say on procurement, and research and develop- ment - at a higher rate than the overall rate, i.e. at % p.a. this broadly based and persistent build-up poses three main risks it adds fuel to the competitive fires and works against cooperation, which was one of the qualities of stage i - stage iii strategy which has been mentioned as highly desirable. because the facts of this russian military build-up are quite unpleasant to contem- plate, it may be overlooked or ignored in the wider world; that could lead to unpleasant surprises later on. or on the contrary the build-up can be exaggerated, as for example our own retired major general keegan has been exaggerating it by saying that the russians are already superior to the united states. and that exaggeration could lead - if it became widely accepted - to unnecessary and unwise concessions in various political areas. let us look for a moment at some specific aspects of the build-up. in the strategic nuclear realm, the soviets' build-up began after the cuba missile crisis of , some years ago. but one of the most intensive periods of the soviets' strategic nuclear build-up has taken place in the last years: that is, since the salt-i agreements. in that five-years period the soviets have deployed three new land-based icbm missiles and two new submarine-based ballistic missiles. all of the new missiles deployed since are equipped with multiple independently targeted re-entry vehicles (mirv's). they have high throw-weights and they have been provided with warheads with increas- ing accuracy. thus, the russians have provided themselves in the last five years with a hard-target counterforce threat to the icbm force of the united states; in addition they have under development one further land-based icbm and two further submarine- based icbm's. moreover, they have deployed the backfire bomber, and since have embarked on a very substantial programme of civil defence. the result is that, between the united states and the soviet union, as far as strategic nuclear forces are concerned, a condition of rough equivalence now obtains. (see chart ii). the chart shows trends over the last several years. it is a chart which indicates a us advantage, until about , in those static measures of the balance which are charted (it's been impossible to chart warhead accuracy): equivalent megatonnage, throw-weight, numbers of strategic nuclear delivery vehicles (which includes land-based icbm, submarine-based ballistic missiles, and strategic bombers), and numbers of war- heads. the soviet union has the advantage in in equivalent megatonnage because their land-based icbm's have high throw-weight. they have a slight advantage in strategic nuclear delivery vehicles. in numbers of warheads the united states has an advantage. what does it mean? all of these things are so abstract. it surely means something, though. one must recall, for example, the reaction of mao-tse-tung in to the russian sputnik. mao took that as meaning the soviets had missile superiority over the united states. he therefore asked khrushchev for help in standing up to the united states over quemoy and matsu. khrushchev refused, and that was one of the things which lead to the great schism between the chinese and the russians. one must also recollect the american presidential campaign of : the so-called missile gap. so, these things do have some kind of political meaning although in themselves they are quite abstract. chart ii us/ussr strategic forces advantage - - emt yield / tw throwweight sndv = stragegic nuclear delivery vehicle .f:.-... sndv warheads ent i let me also mention very briefly the united states' strategic programmes for the future: the new mobile land-based icbm, called mk; the mk a warhead which is a very high yield warhead with great accuracy. (accuracy of any kind of explosive is much more important as far as destructive effect is concerned than is yield. destructive effect varies as the / power of yield, but destructive effect of accuracy varies as the square of the distance from target.) the b-i bomber is in abeyance for the moment, the cruise missile is under development, the trident submarine is in series production as programmed all these us strategic programmes may be accelerated or held in status quo, pending the outcome of further negotiations with the soviet union over the exten- sions of the interim agreement on offensive strategic weapons, which expires october this year. the new salt proposals put forward recently in moscow by the united states were in two categories: one category was a proposal that the vladivostok accord, ballistic missile reentry vehicles, and aircraft delivered warheads warheads he' o tj i which limited both sides to strategic nuclear delivery vehicles, be reduced to treaty form and signed. that proposal was rejected by the russians. the other set of united states proposals was a very far reaching call for substantial reductions on both sides: strategic nuclear vehicles reduced from down to about , limitations on flight testing of new missiles, a ban on cruise missiles having a range in excess of km. and certain assurances with regard to deployment and utilisation of the russian backfire bomber. all these proposals were designed an intended to preserve the invulnerability of the forces of both sides, and therefore to work in the direction of technical military stability. that is to say, the technical charac- teristics of the forces of both sides would not themselves, in a time of crisis, contribute to tension because of tempting vulnerability. i do not think the soviets are interested in things like technical stability. i think the soviets look to their strategic nuclear forces for political effect. the soviets continue to be interested in the competitive political effects of having a huge and dynamic pro- gramme - just as the communities of the middle ages expressed their aspirations, their skills, their strength, through the erection of magnificent cathedrals. i myself doubt that anything like the carter proposals will be accepted by the russians for a long time - probably during the carter presidency. that poses certain risks to the world. but then the russian military build-up in europe causes certain risks also. what are those risks, and why worry about the russian build-up in europe? after all, nato does have the capability to respond adequately to a warsaw pact attack. after all, the wars in the th and early part of the th century had what numerically was the greatest military establishment in the world; there was not anything like the worry that there is today over the russian military build-up in europe. even the soviets - after the collapse of the russian army in world war i - by had rebuilt the red army so that again it was, numerically, the greatest military establish- ment in the world. yet, it was not a source of great concern. why is it a source of concern today? there are three important geo-strategic differences between the situation then and the situation now. world war ii eliminated the military strength of russia's two strongest neighbours and rivals - germany and japan. in the aftermath of world war ii there was a power vacuum on both sides of the old russian empire. as a result of world war ii, the russian military advance into eastern and central europe gave to russia for the first time in history a permanent military deployment in the very heart of central europe. moreover, the russian economy, particularly soviet military industry, was placed in intimate association with the sophisticated and advanced industrial and techno- logical potential of germany and czechoslovakia. after several decades, that has been extremely important to the russians, particularly in the fields of naval ship building, military electronics, and aircraft and missile design and construction. during most of the time since world war ii nato - the west - has relied on two advantages: . nuclear superiority, and . technological superiority. thus, although nato at present does have the capability to respond adequately to a warsaw pack attack, the balance in the future may be less secure than it has been in the past. the immediate questions facing nato - the risks - are not the old easy questions of numerical and qualitative comparisons of divisions, tanks, aircraft and the like. rather they are hard questions, risky questions: is nato prepared to respond on extremely short notice? could nato actually carry out a surge in readiness in a crisis? how capable is nato in making the transition from peace time to war time command and communications systems? how vulnerable are our theater nuclear forces? has nato adequately thought through how her forces and her governments would respond to possible soviet probes on the northern or southern flanks of europe? is nato organized to carry out such responses? the questions point to certain risks, but the real risk is that the competent nato authorities may not ask and answer those questions with sufficient rigour. the situation may put at risk certain political positions, for example in berlin. there has been in recent months a continuous pressure once again on berlin. chancelier schmidt has said he would not repay a pin-brick with a pin-brick and that is a good attitude to have. but the question is: how many pin-bricks does it take to change the four power status of berlin? western europe, all of western europe today, is characterized by weak minority governments. there is in the east a strong civil rights movement. since helsinki there has been a noticeable upsurge in so-called "helsinki-committees ", and civil rights movements, all over eastern europe, and not just in the soviet union. the combination of weakness in the west and pressures for change in the east is a risky combination. beyond europe, the soviets have developed a navy which has world-wide operating capabilities. it has a base near the indian ocean and very substantial fleet operations in the indian ocean on continuing basis. the russians are quite active in africa at the present time. they have a strong interest in the persian gulf - i have outlined that from the standpoint of the energy crisis. and there is a certain risk that the soviets may underestimate either the interests of the west, or the willingness of the west to pursue and defend those interests, due to the lassitude which has been displayed over the last years or so. i must say, however, that the french in providing some support to morocco and to zaire are demonstrating a commendable sense of a strategy for dealing with those risks outside of europe. it is a hopeful sign. conclusion what can one conclude about appropriate strategies for coping with the risks and security problems with which states are faced today? one can read almost daily in the press that the world's resources are distributed inequitably: that % of the earth's popula- tion consume % of the earth's resources after having taken them away unfairly from % of the earth's population. what is left out of that accounting is the fact that the industrious % of the world, which consumes % of the earth's resources, live in a highly evolved culture which is so far the only culture that has demonstrated a capability to efficiency and effectively transform raw resources into food, machinery, fertilizer, and electricity. without these, no part of the world can have any hope. without that high culture, and without that capability, the world would be confronted with the risk of lurching into a disintegrative anticivilization that would be reminiscent of the dark ages. of course, these issues are not new. the original walls of jericho, which were built ten thousand years ago, were built by farmers who had accumulated a surplus of grain which was the object of lustful and aggrandizing attention from desert warriors who did not have the capability of accumulating grain, and who wanted it for them- selves. that is essentially what war has been about ever since: getting somebody else's surplus, or defending your surplus against somebody who could not provide one for himself. today we are faced with a whole range of very grave risks. we are going to have to change, and more rapidly rather than slowly. we are faced not just with an oil and economics crisis, not just a social and political crisis, not just a political-military crisis. one can say that several hours are striking simultaneously on the clock of history. we must face up to the great complex crisis. we must bring to bear the best of our rich and powerful heritage: the best of our intelligence, the best of our imagination, the best of our courage. but about all what is required is a sense and spirit of conviction. it is not exactly stylish in a lecture on strategy to talk about a spirit of conviction, but that is what is required: a conviction which manifests itself in a spirit of concern and engagement. we must go beyond tactics, we must go beyond economics, we must go beyond competition. we have to be clear about a system of values. we must be unambiguous about what our values are: it is only by holding and living according to a set of values that we can have strategies for coping with the trends in risk and security with which we are confronted in the present hour. 	trends of risk and security problems for states and emerging strategies for coping with those trends 	introduction 	oil pricing practices 	global resource shortages 	the russian military build-up 	conclusion the commercial ecology of scavenger capitalism: monsanto, fossil fuels, and the remaking of a chemical giant bartow j. elmore monsanto’s transformation from a chemical firm to a biotechnol- ogy business in the s and s reveals that an increasingly small corporate cartel gained dominion over petroleum refining byproducts and that this concentration of ownership had pro- found implications for the future solvency of monsanto. as the price of petrochemical feedstocks rose, monsanto, a company that made percent of its products from fossil fuels, began to pursue an alternative path to profits. in short, concentrated corporate ownership of critical natural resources forced some companies in the chemical commodity production business to pursue radically new ways of generating cash flow. this was especially true for scavenger capitalists such as monsanto, firms that had historically made their money by scavenging raw mate- rial stockpiles produced by booming commercial industries. for firms invested heavily in commodity production but lacking proprietary claims to critical natural resources, the key was find- ing new ways to make money without depending on fossil fuels. for monsanto, biotechnology offered a way out. “if we grow by using more stuff, i’m afraid we better start looking for a new planet.” those were the ominous words of robert shapiro, monsanto’s chief executive officer in . since taking over the reins of the st. louis-based firm in april , shapiro had helped oversee a radical transformation of the chemical corporation into a © the author . published by cambridge university press on behalf of the business history conference. doi: . /eso. . published online november , bartow j. elmore is assistant professor of environmental history at the ohio state university. e-mail: elmore. @osu.edu . magretta, “growth through global sustainability,” . https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at mailto:elmore. @osu.edu http://crossmark.crossref.org/dialog/?doi= . /eso. . &domain=pdf https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core elmore biotechnology business. true, monsanto had begun this corporate restructuring in the s, but it was shapiro who witnessed the company’s first real success in biotechnology. at that time, monsanto announced that it would no longer generate profits by selling toxic chemicals. as shapiro explained, monsanto was now making money by replacing “stuff with information.” in what some have called the “microsofting” of monsanto, a chemical giant known for such toxic compounds as agent orange and pcbs was now promising to sell genetic software that could restore life on earth. smaller was better for this new monsanto. the firm would attract shareholders not by expanding commodity chemical production but by promoting ecological sustainability through trade in microscopic genetic codes. monsanto’s corporate transformation was unprecedented. no chemi- cal company its size had wholly rebranded itself in such a fashion. it was a dangerous move. so why did monsanto embark on such a risky venture? this question is related to one that has spurred recent business history scholarship. over the past several decades, historians inter- ested in the evolution of american capitalism have sought to explain why so many companies have abandoned commodity production (“making stuff”) as a primary means of generating profits. after all, the winners at the top of the u.s. corporate economy in looked very different than the business titans of . certainly, some time- tested vertically integrated commodity producers, such as the big oil empire of exxonmobil, remained at the top of fortune magazine’s most profitable firms list, but many others had chosen to follow a new path to big money. four of the top ten most profitable firms in —jp morgan chase ( ), wells fargo ( ), citigroup ( ), and bank of america ( )—generated substantial revenue by selling intangible products, such as securities, insurance, and mortgages. atop the list was apple, which made most of its revenue from premium-priced iphones manufactured by third-party entities like foxconn in china. gone from the list were companies like dupont, us steel, and union carbide, which ranked third, seventh, and fourteenth, respectively, on the fortune posting. in short, many of the most profitable firms of the twenty-first century looked very different than the corporate . ibid., . ibid. gender studies professor chaia heller used “microsofting” to describe recent trends in the “agricultural economy.” see heller, food, farms, and sol- idarity, . . monsanto company annual report, . for a list of stock prices from to , see monsanto company annual report, . all annual reports available from proquest historical annual reports. https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core the commercial ecology of scavenger capitalism giants of old, many making money by selling premium technology products or intangible assets, not bulk commodities. in theorizing why this trend occurred when it did, some have aptly noted that “globalization” played a big role. american firms realized that they could use advanced transportation and communication technologies to access natural resources and cheap labor markets in far distant lands, especially in the wake of new neoliberal trade policies—nafta, wto, and others—that reduced the costs of trans- acting business across international borders. rather than manufacture products in-house, firms chose to buy instead of make, acting either as brokers or assemblers of cheap goods produced by independent global suppliers, which competed with one another for big corporate contracts in flush international commodity market. the internet naturally made such global trade networks possi- ble. citing ronald coase’s transaction theory, journalist bob tedechi argued that the e-revolution of the s and s reduced the costs and uncertainties of negotiating and processing business transactions over long distances, thus allowing u.s. firms to scale down their managerial operations and outsource many production operations. new financial institutions and securities instruments developed in the late s also paved the way for a new economy run by busi- nesses that did not vertically integrate into bulk commodity produc- tion. business historian louis hyman, economist william lazonick, and other scholars have focused on changes in financial markets that made old ways of making money passé. investment in the stock market, once an activity reserved for fewer than percent of amer- icans in , became commonplace practice for more than per- cent of u.s. households by the end of the s, thus allowing large amounts of capital to accumulate at america’s brokerage houses. at the same time as more people invested in the stock market, the . current fortune list is sorted by most profitable firms on its website: http://beta.fortune.com/fortune /list/filtered?sortby=profits. for older listings, see fortune’s online archive: http://archive.fortune.com/magazines/fortune/ fortune _archive/full/ / .html . economist richard n. langlois has written extensively about this “de-verticalization” of the corporate economy, perhaps most notably in “vanishing hand.” in this article, langlois emphatically declares, “the visible hand—understood as managerial coordination of multiple stages of production within a corporate framework—is fading into a ghostly translucence” ( ). . bob tedechi, “a nobel prize-winning idea, conceived in the ’s, is a guide for net business,” new york times, october , , c . for a critique of the idea that the internet leads to smaller firms, see hal r. varan, “if there was a new economy, why wasn’t there a new economics?,” new york times, january , ; coase, “nature of the firm”; langlois, “vanishing hand,” . https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at http://beta.fortune.com/fortune /list/filtered?sortby=profits http://archive.fortune.com/magazines/fortune/fortune _archive/full/ / .html http://archive.fortune.com/magazines/fortune/fortune _archive/full/ / .html https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core elmore federal government also began deregulating the banking industry in ways that permitted riskier investments. in these high times for high finance, firms began to realize that they could make tremendous amounts of money by treating business units as assets in a trading portfolio, generating profits through stock swaps and other strategic manipulations of financial markets rather than by increasing the pro- ductivity of various operating divisions. certainly, all of these forces—especially e-commerce and high finance—pushed and pulled corporations in the late s toward a high-tech, information-trading economy in which many businesses shunned commodity production, but for chemical companies there was another factor at play, and one that has often been overlooked: lack of access to critical natural resources. for years, many chemi- cal firms had made big profits sourcing their raw materials from the molecular byproducts of the fossil fuel industry. when oil majors, such as standard oil and shell, refined petroleum to make gasoline (breaking up big chains of hydrocarbons through a heat-intensive process known as cracking), they produced dozens of compounds that the chemical industry highly prized. flush with cash in the gasoline-guzzling days of the mid-twentieth century, the oil majors saw no harm in giving over large quantities of these chemicals at cheap prices to dupont and monsanto, which reassembled them into the plastics, pcbs, and popular products that made the mod- ern world. benefiting from this partnership, by the end of the s, percent of monsanto’s products ultimately came from fossil fuels. however, this cozy relationship began to sour during the s, as refineries increasingly reclaimed chemicals once handed over to chemical companies at bargain rates. this was problematic for prac- titioners of scavenger capitalism, such as monsanto, that had his- torically made their money by feeding off the byproducts of other industries. big oil’s consumption of critical natural resources changed . ott, when wall street met main street, , – , . julia ott shows that the roots of contemporary financial markets date back to the s and s, when the idea of “shareholder democracy” became deeply embedded in the american psyche. see also hyman, “rethinking the postwar corporation.” for more works examining how changes in financial markets shaped corporate restruc- turing after , see lazonick and o’sullivan, “maximising shareholder value”; lazonick, “financialization of the u.s. corporation”; zorn, dobbin, dierkes, and kwok, “managing investors”; englander and kaufman, “end of managerial ideology”; davis, “new finance capitalism.” . monsanto company annual report, . for a brief history of the u.s. petrochemical industry, see aftalion, international chemical industry, – , – . https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core the commercial ecology of scavenger capitalism monsanto’s commercial ecosystem. if the firm was to survive, it was going to have to adapt to a new environment. the term scavenger capitalism is largely absent in the business his- tory literature and journalists rarely deploy the phrase in the popu- lar press. a google books search for “scavenger capitalism” yielded only a handful of results (and business historians penned none of the works). these few google hits included books that merely had the words scavenger and capitalism close to one another in separate sen- tences. a similar search in jstor yielded no results, while a review of proquest historical newspapers resulted in one hit (a los angeles times article about wal-mart). nonetheless, to call pre-biotech monsanto a scavenger capitalist is not an exaggeration. from birth, monsanto pursued capital accu- mulation by recycling waste from other businesses. take caffeine, a product monsanto sold to the coca-cola company in the early twentieth century. up until the s, monsanto produced most of its caffeine from what was called “waste tea leaves”—broken and damaged tea leaves that were unwanted by tea traders. monsanto recy- cled this waste, processed out the caffeine, and made a tidy profit as it supplied the soft drink industry. into the mid-twentieth century, the firm continued to profit by tapping into raw material stockpiles generated by businesses that were, like tea traders at the turn of the century, running their businesses day and night to feed exploding consumer markets. monsanto mined the excesses of the oil industry, an industry whose refineries were running red-hot to keep up with demand of a car-crazed nation. here monsanto’s role as scavenger took on new meaning, as the resources it needed ultimately came from the carcasses of creatures that had died millions of years ago. this was how scavenger capitalism worked in the early twentieth century. it involved finding a business in the middle of a production bonanza and siphoning off some of the byproducts that business . economist richard langlois, in explaining the “vertical unbundling” of big firms in the s and s, argued, “like a biological organism, an organization confronts an environment that is changing, variable and uncertain. to survive and prosper, the organization must perceive and interpret a variety of signals from the environment and adjust its conduct in light of those signals.” despite this brief dis- cussion of the environmental forces shaping corporate governance, langlois was not particularly concerned in his work with ecological influences on the bound- aries of the firm. his statement is, nevertheless, apt when applied to the chemical industry. monsanto’s commercial ecology was changing dramatically by the s, and corporate organisms had to adapt in order to acquire the natural resources they needed to be remain profitable. langlois, “vanishing hand,” . . “retailer forgot what it’s about; wal-mart didn’t,” los angeles times, january , , d . https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core elmore did not particularly prize. in this way, monsanto accrued cheap raw materials to make its chemical creations. this was not necessarily a bad thing. as historians andrew hurley and jonathan wlasiuk have shown, toxic waste generated by oil refin- eries prior to the american petrochemical renaissance often flowed uninhibited into waterways. as a result, monsanto’s recycling prac- tices actually kept some unwanted chemicals from sullying streams near oil refineries (though toxic substances nevertheless found their way into the natural environment further down the commod- ity chain). thus, though we may think of scavengers, either natural or corporate, as repulsive creatures, they often served an important function in repurposing unwanted resources. monsanto’s system of making money through waste reclamation might have continued into the late twentieth century, but by the s the firm’s suppliers began to leave fewer and fewer scraps for the hungry pack of chemical firms demanding more and more fossil fuel inputs. what would be the fate of the chemical industry in this time of scarcity? monsanto’s remarkable transition from chemical king to biotechnol- ogy business showed how contests over natural resources were integral in shaping the corporate economy of the twenty-first century. in the journal of american history interchange concerning recent scholarship on the history of american capitalism, very little was said about the ecological demands of modern corporations. this article addresses this gap, bringing firms back to ground to examine their natural resource dependencies. without cheap oil, monsanto could not thrive, so it got to work investing in a new biotechnology future centered on feeding the world. this is the story of the raw material realities that helped spur that world-changing leap. the making of a fossil fuel scavenger in druggist john francis queeny incorporated the monsanto chemical company in st. louis, missouri, hoping to make millions of dollars selling saccharin, a new artificial sweetener some five hundred . for more on monsanto’s caffeine trade with caffeine, see elmore, citizen coke, – . . see hurley, “creating ecological wastelands”; wlasiuk, “company town on common waters.” petrochemical firms’ ability to capture waste produced by refin- eries should not be overstated. as both hurley and wlasiuk pointed out, pollution problems associated with refineries continued well into the petrochemical boom of the twentieth century. for more on corporate waste recycling in the early twentieth century, see desrochers, “invisible hand”; desrochers, “industrial ecology.” . beckert et al., “history of capitalism.” https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core the commercial ecology of scavenger capitalism times sweeter than table sugar that was derived from coal tar—a black syrupy byproduct of the coal refining industry. a native chicagoan who had worked in the drug business since he was thirteen years old, queeny first became interested in saccharin in the late s while purchasing products for the meyers brothers drug company in st. louis. at that time, american pharmaceutical and chemical companies trailed far behind their european competitors, especially the german powerhouse merck of darmstadt, which, with superior technology and vertically integrated factories, undersold more modest american firms. as a result, meyers brothers depended on merck for its saccharin supplies, acting as a kind of u.s. distributor for the german firm. witnessing the incredible popularity of saccharin, especially within the burgeoning u.s. soft drink market, queeny believed that he could make a lot of money as the first american manufacturer of the chemical. working deep into the evening after shifts at meyers brothers, queeny set up a rudimentary manufacturing plant in down- town st. louis in . with $ , of his own money and a $ , loan, queeny, at the age of forty-two, soon got the plant up and running with the help of three swiss chemists—louis veillon, gaston dubois, and jules bebie—collectively known as the “triumvirate from the swiss alps.” queeny decided to name his firm the monsanto chemical works after his beloved wife, olga mendez monsanto, whose spanish maiden name means “sacred mountain.” the company’s first major cli- ent was the coca-cola company of atlanta, georgia, which purchased virtually all of the chemical firm’s saccharin. to this day, monsanto gives credit to coca-cola for keeping it afloat in the early days. without coca-cola, there would have been no monsanto. from its founding, the monsanto chemical works financial fate was linked to fossil fuels. saccharin came from coal tar, a substance that by the early s garnered the obsession of chemical engineers around the world. coal tar contained a host of organic compounds that could be extracted and recombined to form new synthetic chemicals, including aspirin and caffeine. for monsanto, coal tar was “nature’s storehouse,” a “junk pile of the chemical manufacturer” that offered the chemical firm endless prospects for new chemical development. . for a history of monsanto written by the company’s former director of public relations, see forrestal, faith, hope, and $ , , – . on the history of saccharin, see de la peña, empty pleasures. . forrestal, faith, hope, and $ , , – . for monsanto’s credit to coca-cola, see the company’s website: http://www.monsanto.com/whoweare/ pages/monsanto-history.aspx . spears, baptized in pcbs, ; untitled document dated december , series , box , folder: coal tar, monsanto company records, – , univer- sity archives, department of special collections, washington university libraries (hereafter, monsanto company records). https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at http://www.monsanto.com/whoweare/pages/monsanto-history.aspx http://www.monsanto.com/whoweare/pages/monsanto-history.aspx https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core elmore originally, however, monsanto did not create its products directly from coal tar produced in the united states, preferring to buy intermediates—chemicals that formed the building blocks for more complicated industrial compounds—from europe. in the case of saccharin, monsanto relied on a critical input supplied by the sandoz company in basel, switzerland. the story was much the same for monsanto’s other product lines developed in the first decade of growth—which included laxatives, flavoring extracts, sedatives, and more—all of which came from intermediate chemicals shipped form europe. the outbreak of world war i changed all of this. embargos associ- ated with war meant that queeny had to find ways to synthesize com- pounds starting with domestic raw materials. if monsanto was going to survive, queeny was going to have to find the building blocks of modern chemistry on american soil. however, there was a problem: coal tar was being wasted in the united states. american coal-processing factories had gotten a late start in developing systems that reclaimed tar byproducts; even as late as , monsanto complained that such profligate habits had led to a lack of ample feedstocks needed for domestic chemical manufacture. the company claimed that less than percent of coke ovens in the united states had tar reclamation systems. “the result,” one monsanto executive exclaimed, “has been a shame- ful and needless waste of nature’s stores that should be a cause of humiliation to any country.” tapping into utilitarian rhetoric espoused by progressive era conservationists, monsanto urged coal processors and the american government to do everything in their power to make sure “a large, natural resource will be conserved,” thereby ensuring “profitable employment … for thousands of our people.” in short, monsanto pitched coal tar as a homegrown resource that, if recycled, could liberate america from foreign chemical depen- dencies, and it seemed american coal-processing firms were buy- ing into the patriotic pitch. after all, for coal companies, reclaiming tar seemed like a lucrative way to turn waste into wealth. in the u.s. tariff commission reported that tar reclamation was taking off in the coke industry and calculated that u.s. coal tar production had more than doubled since . monsanto now had access to a . forrestal, faith, hope, and $ , , , , . . ibid., ; spears, baptized in pcbs, . . untitled document dated december , series , box , folder: coal tar, monsanto company records. for more on progressive conservation, see hays, conservation. https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core the commercial ecology of scavenger capitalism valuable industrial waste product that could help it gain the autonomy it needed from overseas suppliers. mining processed coal waste for hidden chemical potentialities, monsanto made big profits in the s. following a brief down- turn in the postwar recession, monsanto saw its net income explode, from roughly $ , in to $ . million in , a fivefold increase. by this time, there was a new president at monsanto. in john queeny had been diagnosed with tongue cancer and was told he only had a short time to live, so the company patriarch decided to trans- fer power to his thirty-year-old son, edgar queeny. an ivy-league graduate known for his often cold and calculating personality, edgar queeny was an ambitious businessman committed to brokering big mergers that would dramatically expand monsanto’s product lines in the decades ahead. he was brazen—so brazen, in fact, that john queeny once quipped that his son’s desire to “change everything” would “ruin monsanto,” but that prediction would prove wrong. by the time edgar stepped down as monsanto’s head in , he could boast net profits totaling over $ million, a far cry from the roughly $ , attained by his father in . one bet that paid off for edgar queeny was his decision to com- mit monsanto to a new fossil fuel feedstock: byproducts of petroleum refining. like his father, he was keenly interested in identifying raw material repositories that promised seemingly endless opportunities for growth, and oil seemed like the next best thing. by the s, the united states had become the largest petroleum producer in the world. the great oil field discoveries of the early twentieth century in california and the southwest, including texas’s great spindletop gusher of , led to a surge in domestic petro- leum production that carried on well into the s. the ease with which oil could be transported through new pipelines made the new fuel preferable to bulky coal clumps. in monsanto president edgar queeny heralded “revolutionary changes resulting from the utilization of petroleum products for the production of chemicals,” and noted that the company could now depend on “relatively cheap . u.s.tariff commission, report on dyes and related coal-tar chemicals, ; “$ , , to be spent on the east side plant,” st. louis post-dispatch, september , , b. . monsanto company annual reports, – . . hubert kay, “monsanto and the american idea,” unpublished manuscript, e- -e- , e- , e- , series , box , folder: “monsanto and the american idea” (hubert kay), st draft (forrestal’s copy), monsanto company records. . monsanto company annual report, ; monsanto company annual report, . https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core elmore and typically american raw materials.” that same year, the company organized the monsanto petroleum chemicals subsidiary, officially signaling its entrance into the petrochemical business. the fact that the oil industry initially chose not to fully integrate into its own chemical manufacture made monsanto’s petrochemical boom possible. business historians from harold williamson to alfred chandler have long held up petroleum majors, such as standard oil, as models of vertical integration. in the visible hand: the managerial revolution in american business, chandler called standard oil “the first of the great integrated industrial consolidations,” and discussed how oil companies purchased “tank cars, ships, and other facilities” to achieve economies of scale. it is true that oil companies controlled expensive fixed assets and combined marketing, transportation, and production operations under consolidated management. in addition, several oil companies began chemical manufacture as early as the s. monsanto’s move into petrochemicals, however, reveals that the oil industry’s vertical integration was never wholly complete. chandler briefly noted this in his work on the chemical industry, but it is a muted point that is worth highlighting here. precisely because oil firms did not initially integrate into total reclamation of its valuable waste products, chemical firms were able to become leading players in the petrochemical processing industry. over the course of the next four decades, monsanto became increas- ingly dependent on both american and international oil refineries for the raw materials it needed. the firm diversified into an amazing array of new petroleum-based product lines after the s, from syn- thetic pesticides to nylon clothing as well as a variety of plastics used for everything from automobile manufacturing to electrical engineer- ing. monsanto was essentially covering america’s cornfields, cars, and consumers with oil. even as the company became addicted to petroleum, monsanto did not initially integrate backward into ownership of its own oil refineries. as it had with coal-processing firms, monsanto chose to act as a buyer of petroleum byproducts rather than its own raw material supplier. this was because it was cheaper to scavenge on the waste byproducts produced by american refineries than it was to . monsanto company annual report, – ; forrestal, faith, hope, and $ , , ; mcneill, something new under the sun, – . on transporta- tion infrastructure’s effects on oil prices, see jones, routes of power, – . for an excellent collection of essays on the history of oil production and consumption in the united states, see black, merrill, and priest, “oil in american history.” . chandler jr., visible hand, , . . williamson and daum, age of illumination; williamson, age of energy; chandler jr., shaping the industrial century, – . https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core the commercial ecology of scavenger capitalism source such products in house. refineries in the united states pro- cessed crude oil into gasoline at a remarkable pace in the s and s, responding to the exploding demand generated by wartime industries and the postwar consumer craze for automobiles. as a result, chemical compounds refined from gasoline began to pile up, creating a stockpile ripe for chemical company exploitation. it was on this pile of refining byproducts that monsanto built its petrochemical empire. throughout the s, monsanto never faced any real problems scavenging raw materials from independent refiners, but this did not prevent the company from considering investing in the oil industry. in monsanto finally decided that its addiction to oil warranted vertical integration into the refining industry. that year the company purchased the lion oil company, breaking with a long tradition of buying instead of making its own petroleum byproducts. a major oil refining and petroleum business based out of el dorado, arkansas, lion oil owned over one thousand oil wells in eleven states, and the company had plans to explore “for new oil and natural gas reserves” in “almost one-third of the nation.” in monsanto announced that lion oil was also investigating drilling opportunities overseas in italy, venezuela, and spain. roughly five years later, the company broke ground on a major refining plant in chocolate bayou, texas. despite these investments, monsanto continued to source most of its raw materials from independent refineries. in , two decades after beginning its own oil exploration, the company reported that in-house refineries supplied just a third of the company’s raw material needs, with two-thirds coming from independent suppliers. monsanto was still beholden to powerful oil interests for the raw materials it needed. the “seven sisters,” which included american giants such as esso and texaco, supplied much of monsanto’s demand before , but increasingly the company also turned to new suppli- ers in the middle east and other parts of the world. over time, this dependency became problematic. by the late s, big changes in the oil industry began to thwart monsanto’s scavenging practices. as ceo richard j. mahoney explained in , several of . in former ceo richard j. mahoney commented on the origins of monsanto’s oil addiction: “the company grew rapidly in the s with the inven- tion of polymerization technology and the availability of low-cost petrochemicals left over from oil refining.” mahoney, commitment to greatness, . . monsanto company annual report, , . . monsanto company annual report, , ; monsanto company annual report, ; monsanto company annual report, . . “energy: probing the problem,” monsanto magazine (spring ), , series , box , folder: monsanto magazine – , monsanto company records. https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core elmore the oil majors—including bp, exxon, and conoco—increased invest- ment in petrochemical manufacturing technology by , using up compounds these firms had once “been ‘giving away’ to monsanto and other chemical converters.” the oil majors were aggressively expanding into monsanto’s commercial markets as competitors and they had a critical advantage: control over petrochemical feedstocks. this was a serious problem for monsanto. scavenging tactics in a time of scarcity: the s oil crisis as monsanto entered the s, big oil was putting the pinch on the company, but other forces were helping to drive up petrochemical feedstock prices. beginning in , oil production in the united states began to decline. it seemed the american oil boom of the early twentieth century was finally coming to an end, and u.s. petrochem- ical companies perforce had to look overseas for supplies. to make matters worse for monsanto, in the early s environmental activ- ists led several successful campaigns to prevent construction of an alaska oil pipeline. for american chemical companies, it seemed fossil fuels in the northern reaches of north america would remain out of reach for years to come. in the club of rome put out their popular polemic, the limits to growth, which warned how natural resource scarcity would soon curb future economic growth. many scholars and businessmen criti- cized limits to growth for its doom-and-gloom predictions, suggesting that technological innovations and new scientific discoveries would allow firms to overcome the limits outlined in the book. despite this espoused confidence in salvation through innovation, some busi- nesses were concerned about dwindling natural resource stocks. in the case of monsanto, the club of rome’s rhetoric was fast becoming a reality. . mahoney, commitment to greatness, . . fred aftalion and alfred chandler noted that some oil companies, such as shell, integrated into production of chemicals as early as the late s, but the scale of integration hastened by the s. for example, exxon chemical company, started in , would become the fourth-largest chemical concern in the united states by . by this time, monsanto had become deeply concerned about the price of raw materials derived from oil and natural gas. aftalion, interna- tional chemical industry, – ; chandler jr., shaping the industrial century, – . . “u.s. oil production keeps rising beyond the forecasts,” new york times, january , , b . . club of rome, limits to growth. for an excellent treatment of this publica- tion’s reception in the s, see sabin, the bet, – . https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core the commercial ecology of scavenger capitalism a year after the club of rome published limits to growth, the organization of petroleum exporting countries (opec) oil embargo hit. this had a devastating effect on the american economy because the united states had become increasingly reliant on foreign oil as the pace of u.s. petroleum production began to decline. opec pro- ducers in arab nations could manipulate world prices through cartel coordination. oil prices more than tripled between and the end of the embargo in march , rising from less than $ a barrel to roughly $ . at first, this was actually a boon for monsanto. as mahoney explained years later, “the oil shock of – … fueled … optimism by creating product shortages that allowed chemical companies to raise their prices substantially.” scarcity was something monsanto could exploit in the short term. in monsanto boasted a “ percent return on shareholders’ equity,” the largest return in company history to that point. nevertheless, in the long run, the oil crisis would worsen an already serious supply-side shortage. u.s. oil production continued to diminish throughout the decade, and in , when iran, under the leadership of revolutionary islamic fundamentalist ayattolah khomeini, broke off diplomatic relations with the united states, petroleum prices skyrock- eted to more than $ a barrel. monsanto simply could not manufacture a profit margin if it had to purchase such expensive feedstocks. fearing financial ruin, monsanto went to congress to seek relief from its supply dilemma. in , ernest s. robson jr., energy and materials executive at monsanto, proposed that congress take mea- sures to reduce gasoline consumption by approximately percent. this would free up energy for industry and consumers alike. in impos- ing new regulations on fuel consumption, however, robson argued the government need not focus on monsanto: “we do not need regulation to make us conserve. we know fuel conservation is in the best interest of our industry as well as the united states and its citizens.” besides, robson added, “it must be recognized that there is no significant conser- vation or conversion potential for petrochemical feedstocks.” monsanto was already operating at maximum efficiency, robson argued. . “oil tops inflation-adjusted record set in ,” new york times, march , ; nelson, guide to the presidency, . . mahoney, commitment to greatness, . . ibid. . “oil tops inflation-adjusted record set in ,” new york times, march , . . u.s. house committee on ways and means hearing, energy crisis and proposed solutions, part , march , , , cong., st sess., (hereafter, u.s. house committee, energy crisis). https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core elmore throughout the s, monsanto pitched itself as a paragon of conservation rather than a profligate consumer of scarce natural resources. according to monsanto, the company had always been a scavenger, turning waste products of the oil industry into valuable consumer and industrial products. take plastics, the company argued in a company newsletter: “in earlier days the raw materials used to manufacture most plastics once went out the stack as waste and gases, thus actually contributing to air pollution. plastics technology, therefore, is in fact conserving what once was wasted.” monsanto was not part of the problem; it was the solution. mining the dustbins of other industries, monsanto was repurposing refiners’ refuse. according to monsanto, the firm’s waste recycling practices on the frontend of the business were just part of what made the company great for a society facing scarcity. in his testimony to congress, robson posed the rhetorical question: “why can’t we just cut out all those petrochemical-based products and go back to natural materials?” to do so, robson, argued, would have devastating consequences for the environment and national security. “take textiles, for example. to return to natural materials would require the planting of mil- lion new acres of cotton … acreage [that] would have to be taken from food production.” much the same with synthetic rubber, which, if replaced with natural sources, would expose “the united states to future embargo of another critical material produced abroad.” the only real, tenable solution to the country’s energy crisis was more oil: “the name of the game must be greater domestic supply.” even if congress put its government muscle behind new drilling projects, this was never a real solution for monsanto. as one com- pany official explained, the company knew that it was a “midget compared to the major [oil] producers,” generating just , bar- rels of oil a day, compared to the , – , produced by “one of the ‘small’ majors.” almost twenty years since deciding to buy lion oil, it was clear monsanto was never going to be able to supply its own petroleum needs, and the prospects of relief from outside the company were bleak. as monsanto magazine noted, “looking for oil and gas in traditional domestic areas” was “no longer a highly profitable business,” and even if big refineries managed to find new reserves, it was clear these firms were not giving away their valuable . “a special report: plastics and the environment,” monsanto: world head- quarters newsletter , no. (june , ), , series , box , folder: accounting department (folder ), monsanto company records. . u.s. house committee, energy crisis, . . “the search for oil: every little bit counts,” monsanto magazine (winter ), – , series , box , folder: monsanto magazine – , monsanto company records. https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core the commercial ecology of scavenger capitalism petroleum byproducts like they had in the past. in this new era of big oil integration into chemical manufacture, raw materials were going to be hard to come by for chemical companies lacking access to vast oil reserves. thus, as monsanto entered the s, it could no longer scavenge on cheap natural capital as it had in the s and s. declining american oil production, coupled with petroleum firms’ consolidated control of compounds released during refining processes, portended major problems for the st. louis chemical company. considering these realities, the task before monsanto was to figure out a way to make big profits without relying on big oil. the “microsofting” of monsanto: biotech as a solution to natural resource scarcity gender studies scholar chaia heller used the term “microsofting” in to describe monsanto’s transformation from making chemicals to selling seeds. as she explained, “just as customers must buy windows when they buy many pc computers, farmers must buy chemical and other inputs when they buy genetically modified seed.” heller’s comparison of microsoft with post- s monsanto is apt, because, by the s, executives at the st. louis firm were very much enamored with the business models coming out of silicon valley. as bob shapiro made clear in his harvard business review interview, monsanto’s top executives believed that “the substitution of information for stuff is essential to sustainability.” in the future, the firm would sell “dna-encoded information” to america’s farming families, giving them the genetic software they needed to reap profit from the earth. economic pressures brought on by a changing commercial ecol- ogy pushed the company to make this big leap. monsanto’s financial returns were dismal in . that year net profits were less than half of what they had been in , dropping from roughly $ million . ibid.; chandler jr., shaping the industrial century, . when i speak of scarcity in this article, i am not suggesting that global peak oil production had already taken place by the s. annual global oil production would continue to rise in the final decades of the twentieth century, but monsanto did not know this would happen during the energy crisis. in the s, oil companies recycled their petrochemical feedstocks, thereby reducing supplies available to the st. louis chemical firm. . heller, food, farms, and solidarity, . . magretta, “growth through global sustainability,” . . ibid. https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core elmore to $ million. it seemed the oil problem was not going away and it was clearly affecting the chemical companies’ ability to sustain growth. something had to be done. in this time of crisis, mahoney first became president and then also ceo of monsanto. he had witnessed firsthand how changes in the petro- leum industry had affected the petrochemical industry in the s. a chemist by training with a degree from the university of massachu- setts, amherst, mahoney joined monsanto as a chemical engineer in . he had worked in pesticide, fertilizer, herbicide, and plastics divi- sions of the firm, and had an intimate knowledge of the fossil fuel feed- stocks that fed these enterprises. a confident and disciplined worker, he lived by the motto filo—first in, last out—recognizing that he had to pay his dues if he wanted to rise to the top. when he became ceo in , he felt he had put in the long hours and earned the right to speak confidently about where the company needed to go in the future. for mahoney, it was clear that monsanto’s inability to scavenge for cheap feedstocks made future growth in the petrochemical business impossible. later in his career, reflecting on the early s, he wrote, “the once cheap hydrocarbons were no longer cheap. whereas monsanto once took cents’ worth of oil or gas hydrocarbons and added cents’ worth of technology, we were faced with buying -cent hydrocarbons and selling a finished product into a market- place that allowed us to add only cents of our technology. the value we added was dwindling—a guaranteed recipe for disaster.” in monsanto explained to its shareholders that it had no choice but to make big changes. that year, chairman of the board john hanley reported that he, mahoney, and other top leadership at the firm had “candidly debated the proper course for the future” and decided that “raw materials, particularly petroleum-based ones, had become too large a component of too many of our products.” over percent of what the company sold came from hydrocarbon feed- stocks, making the company unreasonably “vulnerable to the cyclical fluctuations of the economy.” the company planned to slowly divest from commodity chemical production while pursuing a “strategy to expand toward higher-value proprietary and specialty products.” hanley and mahoney tapped howard a. schneiderman to lead this new product development initiative. a former professor and dean at . monsanto company annual report, ; monsanto company annual report, . . mahoney, in my opinion, . . mahoney, commitment to greatness, . . monsanto company annual report, ; monsanto company annual report, ; “dramatic climb by oil prices gives u.s. chemical industry executives a headache,” the sun (baltimore), december , , k . https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core the commercial ecology of scavenger capitalism the university of california–irvine, schneiderman came to monsanto in to help expand a pilot biotechnology program. he was one of the leading figures in developmental biology, pursuing cutting-edge research in genetics that focused on dna codes regulating cellular growth. in schneiderman told shareholders that his prime objective was to develop new products that were “less dependent on raw material costs” and which “have a strong proprietary character.” without going into research specifics, he added: “we are going to be selling products for what they do rather than what they are.” in monsanto spent over $ million dollars in biotechno- logical research and development, creating the chesterfield village life sciences laboratory. the company invested in a variety of proj- ects, from developing a bovine growth hormone (rbgh) that would help cows produce milk, to isolating genetic sequences that would engender pesticide-resistance in genetically modified (gm) crops. monsanto was certain that development of these products would take time, but expressed hope in that “important traits of plants, including stress-, herbicide-, and pest-resistance … may be possible to transfer … to important crop species in the next few years.” while investing in biotechnology, monsanto simultaneously got out of the petrochemical business at a remarkable pace. in mahoney reported that the company had “closed down businesses with sales of more than $ billion,” including its fossil-fuel enterprises and much of its commodity chemical operations. as a result, the company’s invest- ment in bulk commodity chemical production declined from percent of total assets in to just percent eight years later. monsanto’s competitors did not follow the same path as the st. louis firm. on the contrary, dupont decided that its best bet was to acquire conoco oil in . much like monsanto’s lion oil merger in , dupont believed the conoco purchase would give the company “a stronger position to compete with the oil companies.” this was a big deal, costing over $ billion and making it, according to the christian science monitor, “the nation’s largest merger.” dupont was doing what it thought it had to do to thrive in a new . remarks to shareholders by howard a. schneiderman, monsanto share- holders meeting, april , , , series , box , folder: hanley, john w. (remarks [shareholders mtg., - ]), monsanto company records. . monsanto emc report on biotech, april , , series , box , folder: biotechnology (association of reserves, – ), monsanto company records; mahoney, commitment to greatness, . . mahoney, commitment to greatness, – . . “takeover of conoco backed by du pont’s shareholders,” new york times, august , , d . . ron scherer, “du pont to swallow conoco in record-breaking merger,” the christian science monitor, july , https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core elmore commercial environment. dow chemical also kept a sizable portion of its commodity chemical business into the s, hoping to weather the storm. as late as , the new york times reported that dow’s “com- modity chemicals still represented nearly a third of the company’s sales, more than at competitors like monsanto and dupont.” chem- ical companies were experimenting with different strategies, watch- ing one another adapt to the realities of the day. over time, however, both dow and dupont began to follow monsanto’s lead, aggressively unloading their bulk commodity chemical assets, which had become by “the dirty word of the industry,” according to the wall street journal. dupont dumped conoco in and a year later acquired pioneer hi-bred international, signaling its commitment to securing a top position among firms with capital investments in biotechnology. by the s, headlines read “dow chemical lists commodity chemicals businesses for sale,” and dupont investor reports explained spinoffs of chemical assets as “dupont’s transformation to a higher growth, higher value, global science and innovation company.” long before all of this, monsanto had been more radical in its divestment strategy. in the s, monsanto’s mahoney believed reducing its reliance on petrochemicals promised his company liber- ation from the vagaries of the natural world and international trade. this, after all, had long been the core mission of the chemical industry: to break through ecological limits imposed by nature through clever manipulation of molecular compounds. in , for example, monsanto argued that its production of synthetic caffeine would “not be subject to the vagaries of nature,” and when the company finally succeeded in producing caffeine from coal tar, it called the achievement “another chemical victory over nature.” roughly forty years later, richard mahoney made a similar pitch. the company had finally shrugged off its “traditional dependence on cyclical com- modity businesses” that placed the company forever “at the mercy of . “for dow chemical, the good times stall,” new york times, october , , d . . “dupont agrees to purchase of seed firm,” wall street journal, march , , a . . “dow chemical lists commodity chemicals businesses for sale,” reuters, december , , http://uk.reuters.com/article/dowchemical-assets- idukl n jh uc ; “dupont completes the spin-off of the chemours company,” dupont company investor relations website, http://investors.dupont. com/investor-relations/investor-news/investor-news-details/ /dupont- completes-spin-off-of-the-chemours-company/default.aspx. for a discussion of dupont’s evolution up to the s, see ndiaye, nylon and bombs. . company publication written by braxton pollard, “now–synthetic caffeine,” undated document, series , box , folder: caffeine (general), monsanto company records; report on caffeine and theobromine, prepared by john ragsdale, , ibid.; news release on monsanto synthetic caffeine operations, , ibid. https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at http://uk.reuters.com/article/dowchemical-assets-idukl n jh uc http://uk.reuters.com/article/dowchemical-assets-idukl n jh uc http://investors.dupont.com/investor-relations/investor-news/investor-news-details/ /dupont-completes-spin-off-of-the-chemours-company/default.aspx http://investors.dupont.com/investor-relations/investor-news/investor-news-details/ /dupont-completes-spin-off-of-the-chemours-company/default.aspx http://investors.dupont.com/investor-relations/investor-news/investor-news-details/ /dupont-completes-spin-off-of-the-chemours-company/default.aspx https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core the commercial ecology of scavenger capitalism forces outside [its] control.” this was a new monsanto. “restructured to reduce [its] exposure to the uncontrollable,” the company would now be “far more makers of conditions than responders.” biotechnology offered an attractive means of moving monsanto beyond oil. limiting its frontend investments in bulk production of material products, monsanto planned to sell a microscopic product—a kind of genetic software—that could be inserted in the hardware of plant and animal life. shot into seed germplasm with the help of a “gene gun,” this software could be rapidly dispersed to farmers across the globe. added to plasmids in microscopic bacteria, genetic cas- settes could turn living cells into “biofactories” capable of churn- ing out copious quantities of valuable antibiotics, pesticides, and hormones. thus, lab-created biotech products promised to radically reduce monsanto’s demand for petroleum feedstocks. monsanto’s transition to this new corporate model took time, and the company even went into the red for a few years, but by the mid- s the company could boast a series of successful new gm and biotech products that promised a bright future for the firm. in monsanto released roundup ready (rr) soybean seeds, which were genetically modified to tolerate monsanto’s signature herbicide, roundup, one of the few chemical products monsanto held onto as it transitioned to biotechnology. that same year, the company intro- duced bollgard, a cotton seed that contained a bacteria-derived gene coding for the production of a toxin called bt that repelled insects. by this time, bob shapiro had replaced richard mahoney as chairman and ceo of the company. shapiro had come to the firm in when monsanto bought searle, a pharmaceutical company known most notably for its successful aspartame sweetener, nutras- weet, which shapiro had helped launch in the early s. unlike mahoney, who was a staunch republican and prolific conservative columnist for newspapers across the country, shapiro was a demo- crat, someone sympathetic to the political rhetoric of the liberal left. a fan of early s environmental luminaries, such as paul hawken, bill mcdonough, and amory lovins, shapiro believed that biotech- nology could be used to improve the health of the global environ- ment, a cause he fervently supported. as shapiro explained, “the earth’s ecological system cannot withstand unlimited increases in the amount of material produced and consumed, but it can withstand expo- nential increases in knowledge and information.” throughout the . mahoney, commitment to greatness, – . . monsanto company annual report, . . carl franken, “monsanto breaks the mold,” tomorrow magazine (may/ june, ), , series , box , folder: shapiro, r. (speeches) , monsanto company records. https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core elmore s, shapiro preached monsanto’s mission to “produce much more with much less raw material and energy.” shapiro ballyhooed that biotechnology was good for both monsanto and its traditional clients, especially farmers around the world. gm crops that produced their own bt toxin would allow farmers to reduce their dependence on pesticides, which came from expensive petroleum feedstocks. furthermore, gm plants would allow farm- ers to cut down on fertilizer demands and weeding operations, since monsanto’s herbicide-resistant crops would allow farmers to spray fields liberally with chemicals that killed unwanted plant species. by the s, monsanto lauded what it called “no-till farming,” arguing that gm crops would eliminate the need for frequent tillage, thereby helping farmers to “reduce fuel use by at least – gallons per acre.” a firm that had made its name feeding farmers petrochemical prod- ucts was now suggesting it could help curb farmers’ dependence on fossil fuels. in other words, monsanto was turning concerns about oil scarcity into a powerful marketing opportunity, recognizing that the threat of fossil fuel shortages could actually help it sell new products rather than impede its growth. monsanto’s promise of petroleum liberation did not prove entirely unfounded. studies in the s and s showed that gm crops planted via no-till techniques helped farmers reduce fuel costs asso- ciated with maintaining farmland. for example, farmers using herbicide-resistant crops did not have to spend as much time removing weeds from their fields and therefore did not have to run diesel- guzzling tractors as long as they had in the past. nevertheless, farmers that switched to gm crops never fully curbed their dependence on oil. after the s, farmers did begin to reduce their fossil fuel use, thanks to improved machinery and new tilling strategies, and total energy consumption on u.s. farms dropped from . quadrillion btu to . quadrillion btu by . gm technology may have contributed to this, but since , and in the period of gm crops most rapid expansion in the united states, energy use leveled off at around . btu, where it remained as of . in short, major reductions in fossil fuel use on farms largely predated the golden era . robert shapiro, “a new model of growth and sustainability,” strategy and leadership (may/june ), , series , box , folder: shapiro, r. (speeches) , monsanto company records; monsanto company annual report, . . monsanto company pledge report, , proquest historical annual reports. for data on bt cotton and pesticide use, see stone, “field versus farm in warangal.” . duke and powles, “glyphosate-resistant crops and weeds,” ; soane et al., “no-till,” . https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core the commercial ecology of scavenger capitalism of gm crop adoption and in the heyday of gm growth, the promise of dramatic energy savings never materialized. indirect fossil fuel consumption through the use of fertilizers and herbicides, both synthesized in factories dependent on substantial fossil-fuel inputs, also remained high by the s. in fact, according to a study published by the nonprofit organization food and water watch and publicized in forbes magazine, the total amount of glypho- sate herbicide “applied to the three biggest ge crops—corn, cotton and soybeans—increased -fold from million pounds in to million pounds in .” of course, much of this glyphosate still came from monsanto in the form of roundup, a trademarked chemical monsanto never abandoned because it continued to yield strong returns for the firm. it seemed monsanto was still willing to sell oil-dependent products to farmers as long as they could charge a premium price. fertilizers derived from fossil fuels also remained in high demand on farms using monsanto gm seeds in the s. despite a sharp decrease in fertilizer use on u.s. farms after —caused largely by rising fossil fuel costs that drove up prices—fertilizer use began to climb once again after , from million tons that year to million tons a year later. world demand for fertilizers also grew between and , especially in china and india, where gm crops made major inroads in the s. in short, fossil fuels were still an integral part of monsanto’s moneymaking enterprise because the company’s farming clients still depended on copious quantities of synthetics derived from oil and gas to survive. thus, roughly two decades after monsanto began its biotechnology business, it had failed to deliver on its promise to replace “stuff with information.” in fact, it seemed new information actually meant more stuff, at least in the case of herbicide for farmers now reliant on roundup ready crops. . on energy use reduction in u.s. agriculture from to , see schnepf, energy use in agriculture. on energy use since , see beckman, borchers, and jones, agriculture’s supply and demand. the author would like to thank kansas state university professor and sustainable agriculture specialist mike bomford for his assistance in finding these materials. . beth hoffman, “gm crops mean more herbicide, not less,” forbes, july , . . for another study detailing increased herbicide use on gm crops in the united states, see benbrook, “impacts of genetically engineered crops,” . charles m. benbrook is a harvard-trained agricultural economist now at washington state university. for studies detailing energy estimates for herbicide and pesticide production, see helsel, “energy use and efficiency”; helsel, “energy and alternatives”; helsel, “energy in pesticide production and use.” . united states department of agriculture, economic research service, “fertilizer use & markets,” http://www.ers.usda.gov/topics/farm-practices- management/chemical-inputs/fertilizer-use-markets.aspx#.u_ j bxdud ; food and agriculture organization, current world fertilizer trends, . https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at http://www.ers.usda.gov/topics/farm-practices-management/chemical-inputs/fertilizer-use-markets.aspx#.u_ j bxdud http://www.ers.usda.gov/topics/farm-practices-management/chemical-inputs/fertilizer-use-markets.aspx#.u_ j bxdud https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core elmore conclusion in bob shapiro oversaw the final stage of monsanto’s meta- morphosis into a biotechnology business. that year, the company unloaded its remaining chemical manufacturing assets to a new firm called solutia, finally saying goodbye, once and for all, to almost all of its chemical past—except precious brands such as roundup. for some outside observers, it was the backend of monsanto’s business that bred the solutia divestment. after all, in the s, the company faced a multimillion-dollar class action suit brought by the citizens of anniston, alabama, who had suffered debilitating ailments caused by monsanto’s unregulated dumping of toxic polychlorinated biphenyl (pcb) chemicals in city waterways. expensive proposals for cleanup of toxic wastes at other company sites loomed as well. thus, monsanto’s spinoff of its chemical business, many environmentalists argued, was merely a crass effort to unload toxic environmental lia- bilities weighing down the firm. writing to the new york times about shapiro and monsanto in , one concerned citizen exclaimed, “their goals are not environmental preservation but profit, profit, profit. these guys aren’t being green; they’re seeing green!” this makes for a tidy story, but it does not take into account the deep historical roots of monsanto’s dramatic transformation. concerns about environmental liabilities at the backend of the business certainly shaped corporate decisions, but pressing natural resource problems at the frontend of the business also influenced monsanto’s radical rebranding. in the late s, oil prices were rising, and monsanto was having trouble creating the profit margins it needed to make money off its chemical commodities. in short, concerns about ecolog- ical resources were at the heart of the corporate restructuring story, but it was supply-side shortages, not simply downstream environ- mental dilemmas, that prodded corporate leaders to make the daring jump into the biotechnology beyond. monsanto’s story should inspire scholars to think more broadly on how natural resource demands reshaped corporate america from to today. the leaning of the corporate economy that began in the s—a metamorphosis chronicled by historian louis hyman, economist richard langlois, and others—occurred precisely as america faced an energy crisis that forced businessmen, politicians, and citizens to question dangerous dependencies on fossil fuels. . “it isn’t easy being green,” new york times, september , , . for an excellent history of the pcb conflict in anniston, alabama, see spears, baptized in pcbs; love, my city was gone. . monsanto company annual report, . https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core the commercial ecology of scavenger capitalism this connection between some firms’ limited access to critical nat- ural resources and corporate restructuring during this period needs more scholarly attention. after all, corporations are organisms that metabolize natural capital to generate financial capital. when natu- ral resources become scarce, corporations make evolutionary adapta- tions to adjust to their commercial ecosystem. that is exactly what monsanto did to survive, abandoning its scavenging practices in an environment that was becoming increasingly hostile to its sur- vival and venturing to the new fertile field of biotechnology, where alpha predators had yet to emerge. now, monsanto sits atop the food chain—quite literally. getting there was a risky gamble, but it seems to have paid off. the questions today are: what will be the fate of the oil titans that grew so large and so big by hording fossil fuels and the derivatives thereof? what will happen to these corporate creatures that depend on energy-dense diets to survive? after all, those who study the natural world know that large organisms with such tremen- dous consumptive needs are often the most vulnerable when environ- mental conditions change. today, some are calling for a transition to a world economy that does not depend on fossil fuels. if big oil does not make aggressive adaptations to this new commercial ecosystem, petroleum potentates may well go the way of the jurassic giants they now dig up from their graves. bibliography of works cited books aftalion, fred. a history of the international chemical industry: from the “early days” to . philadelphia: chemical heritage press, . bartow, j. elmore. citizen coke: the making of coca-cola capitalism. new york: w. w. norton, . chandler, alfred. shaping the industrial century: the remarkable story of the evolution of the modern chemical and pharmaceutical industries. cambridge, ma: harvard university press, . ———. the visible hand: the managerial revolution in american business. belknap press of harvard university press, . club of rome. the limits to growth: a report for the club of rome’s project on the predicament of mankind. new york: universe books, . de la peña, carolyn. empty pleasures: the story of artificial sweeteners from saccharin to splenda. chapel hill: university of north carolina press, . . langlois, “vanishing hand”; 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, http://www.hrpub.org doi: . /aep. . energy scenario and diversity in pakistan: an energy security perspective ruqqaya safeer , dr. noor fatima ,* mphil researcher, department of international relations and political science, international islamic university, pakistan assistant professor, department of international relations and political science, international islamic university, pakistan copyright© by authors, all rights reserved. authors agree that this article remains permanently open access under the terms of the creative commons attribution license . international license abstract energy being the lifeline for socio economic development has become the leading issue of st century. there is global increase in demand of energy and it will continue to increase due to immoderate energy consumption. today there is global fear of energy crisis as world primary demand of energy is expected to rise about . percent annually in next twenty years. south asia is expected to give largest share for increase in global energy demand. pakistan being a developing state is facing acute energy crisis that has hampered the socio-economic development. the energy crisis of pakistan and its spillover effects on efficiency of other sectors especially economic sector has created serious issues in pakistan for the last two decades. the overreliance on imported energy resources to satisfy the demand and less emphasis on the development of domestic energy resources is deteriorating the socio-economic conditions of country. there are two major sources of energy being used in pakistan, renewable and non-renewable sources. in pakistan, there has been more focus on non-renewable sources of energy which are largely acquired through imports of oil to satisfy the increasing demand. the state energy policy has somehow has not able to match with the increasing energy demand and therefore citizens angered by frequent power outages demonstrate to protests and riots. thus, this article, accentuate on the need of the utilization of the indigenous resources of energy to fulfill the energy need and to eradicate the acute crisis of energy. this research will also assess the issues in power policy and power sector institutions of pakistan. keywords energy, pakistan, indigenous resources, renewable energy, non-renewable energy, energy mix, diversification . introduction energy security has become the top priority issue around the globe. the increasing quest and worldwide increasing demand of energy has made energy an important strategic reserve. the global depletion of conventional energy resources with every tick of clock and increasing energy demand round the clock compelled the world to opt for alternative methods of energy production. therefore, globally there is intensifying trend towards diversification of traditional energy mix. the hubert hypothesis of peak oil and energy inclusion in un sustainable development goals further alarmed the nations to renew their energy resources. peak oil is the assumed point where world fossil fuel production predominantly oil will follow downward trend where world would be left with very rare fossil resources. [ ] it imbued the nations to seek alternative sources of energy for sustainable development. though hundred percent conversions from conventional to unconventional sources of energy is not a matter of day it will take time. however, some countries unexpectedly had shown very swift movement in diversification of their energy mix. pakistan being a developing state is facing acute energy crisis that has hampered the socio-economic development. in pakistan there is very slow development towards adopting alternative sources of energy. pakistan despite having enough resource endowments is facing unprecedented energy crisis that is lingering day by day. this severe energy crisis and its domino effect on economic sector is leading country towards anomalous economic recession. the socio-economic issues attached with this crisis are demanding pakistan to speedily diversify its energy mix. presently, pakistan is heavily dependent on imported sources of energy for satisfying most of its energy need. there is instant need to expedite diversification process otherwise pakistan will remain far behind in world of rapidly growing economies. the lack of sectoral cohesiveness and interest has failed to formulate integrated policy with vision and intellect of whole energy sector. each sub -sector working under energy sector is pursuing different policy that come out with unbalanced energy mix and overreliance on imports. energy scenario and diversity in pakistan: an energy security perspective despite of indigenously available coal and hydro potential country heavily relies on imported oil and gas imports for power generation. it shows lack of cohesion among different ministries especially among wapda and nca as well as ministry of energy. [ ] the ignorance factor further delays any progress and leads to seek short term solutions for recurring energy shortfalls rather than bringing pragmatic solutions for controlling energy deficit. moreover, the financial issues and insufficient research capability also hinders in bringing alternative sources of energy to satisfy growing demand of energy. thus, the focus of this research is to investigate the root causes of pakistan’s energy crisis keeping in view the issues in energy sector, policy making and implementation process. the question addressed in this research is why pakistan is facing unprecedented energy crisis despite having indigenous potential to fulfill the energy demand? how the policy and sectoral ineptness is responsible for pakistan’s energy deficiency? the research also endeavors to suggest certain policy options for the future energy policy of pakistan to satisfy the energy demand. . literature review the issues of pakistan energy sector can be divided in to three categories; it includes policy related issues, issues in governance, financial issues and technical issues. the fragmented structure of the sector and lack of collaboration between various entities is a serious issue. this issue affects the institutional working and smooth implementation of policies. [ ] pakistan electricity sector is facing the issues of poor governance, ineffective planning and political influence in policy decisions. [ ] pakistan energy crisis is more of a governance issue than supply, inefficiencies in governance, problems of circular debts, losses of t&d, electricity theft and poor management are not due to supply shortage but indication of governance inefficiency. energy crisis is not limited to energy sector only but it creates serious consequences for other sectors as well, from industry to economy, every sector is being affected by energy crisis. now energy has got prominent space in election campaigning and used by pakistani politicians as political slogan in their speeches. [ ] from onwards numerous energy plans were given by the government of pakistan, though proper policy document was given in to fulfill the growing demand of energy. from s onward number of policies announced but major flaw in all these policy documents was the lack of integration and ignorance toward utilizing tools of modeling e.g. enpep, balance, leap, markal/times. these tools are very helpful in policy planning and are used widely around the globe. [ ] there is no integrated energy policy in pakistan as there are separate policy documents for renewable policy, power policy, petroleum policy. though policy formulation is not an easy job. the policy has to consider the stakeholder interest as well as to take care of those who can’t defend themselves. [ ] pakistan needs a well-integrated policy to overcome the crisis of energy. there are more political slogans and less policy actions and outcomes that fulfill the energy demand of population. political slogans can please people for only short period ultimately this is proper policy planning and implementation that works. [ ] pakistan have indigenous options available for overcoming energy crisis but these options have been ignored by policy planners from about three decades. there is need of integration and harmonization of policy governance to overcome this lingering energy crisis. [ ] energy sector need a well-planned and clearly articulated policy for the development. there has been no effort made in history to devise an integrated policy of energy. there are number of piece-meal policies introduced in country, however these policies were nor effective neither capable for bringing energy security in the country.[ ] although pakistan energy crisis is chronic and need long term planning, but energy demand can also be mitigated by taking some short term measures at individual level through responsible use of energy at homes, in offices, universities and other sectors. [ ] however, mirza bergland and afzal stress more on establishment of energy institution and laws. there is need to incorporate the laws to control the energy consumption and establishing institution that suggest energy conservation methods. according to an assessment of enercon pakistan has potential to save around percent of energy by responsible use of energy. furthermore, the energy conservation can save us$ five billion annually for pakistan. in this connection, universities and think tanks can also play an effective role in developing the energy conservation culture in pakistan. it and engineering universities can help in technical areas; they can help in building insulation, efficient appliances and by improving boiler technology. a large portion of energy due to technical inefficiencies and transmission losses is being wasted. engineering institutes can also help in mitigating these line losses. moreover, engineering universities can help in generation by improving the working of power plants. social science universities can also play an effective role in promoting energy conservation trend .these universities can start public campaigns to create awareness in masses about energy conservation benefits.setsudenan energy conservation campaign was launched in japan for energy conservation that was very successful, pakistani universities can also start similar sort of movements for developing energy conservation culture in country. furthermore, think tanks can also play crucial role in energy conservation activity. think tanks can disseminate the message of energy conservation through their research publications, seminars and conferences. [ ] advances in energy and power ( ): - , . pakistan’s current energy scenario . . petroleum resources/ oil the generation of electricity from petroleum resources has decreased to percent around the globe. [ ] however, pakistan is still heavily reliant on petroleum resources for satisfying its energy demand. oil constitutes a major share in pakistan energy mix. presently oil contributes percent in total energy mix. there is extensive use of oil in power and transport sector of pakistan. [ ] according to the data provided by global economic indicators the oil consumption of pakistan has quadrupled from year to . the oil consumption has reached to thousand barrels per day ( ) from thousand barrel per day ( ). the oil production of pakistan in fy has increased by . percent p.a. it has increased from , barrels per day to , barrels per day. [ ] pakistan’s indigenous oil resources are not enough for satisfying oil demand. therefore, pakistan seventy percent of oil demand is fulfilled by imports. most of oil imports are made from middle eastern region from worth us dollar . billion with import of . million tons of oil. [ ] this wide scale import and no export is pushing country toward balance of payment crisis. . . natural gas natural gas is the less polluting and environmental friendly fuel among other fossil fuels. pakistan energy sector is primarily dominated by gas. the share of natural gas in pakistan power generation is . % .according to estimates pakistan is a major gas consumer country rank twenty third in world with consumption of , , thousand cubic meters .[ ]the production of gas in pakistan is around . billion cubic feet per day.[ ]the production of gas has stagnated from last five years .the exploration of approx trillion cubic feet of natural gas during year in province of baluchistan at sui was a huge contribution to pakistan energy sector. pakistan was self-sufficient in meeting its gas demand till .due to large scale utilization of gas in various sectors its demands has increased while supply growth was relatively low. this gap between supply and demand as well as misallocation of gas created shortage of gas in pakistan. in a gas allocation policy was formulated to allocate the gas supply to various sectors in priority order. in policy priority list industry and cng were fourth preference but both became the largest beneficiaries in year to .the increased share of gas in other sectors decreased the share of gas in power sector. diversion of gas to other sector increased the share of expensive imported oil in power sector. [ ] the improper implementation and some vested interest failed to implement the formulated plan properly. the failure to properly implement formulated plan and rapid increase in demand instigated gas crisis in pakistan. to meet the increase demand of gas government of pakistan has finalized major gas import deals under tapi and ip projects. these two gas import projects are expected to satisfy the increasing demand of gas consumption. . . compressed natural gas (cng) compressed natural gas has wide application as a vehicle fuel globally. presently almost world million vehicles are using cng. the use of cng as vehicular fuel was introduced in pakistan in . government of pakistan encouraged the use of cng as a vehicular fuel to minimize the use of expensive imported liquid fuel and due to its lower environmental pollution. in world seventy cng user states pakistan ranks at no with almost , vehicles using cng .[ ] but, due to depleting natural gas reserves and its increasing demand in last few years the supply of cng has been disrupted in country. the disruption in supply resulted in periodic closure of cng stations and then large queues of vehicles at cng stations left no option for cng consumers instead switching to petroleum again. . . liquefied natural gas (lng) lng is conversion of natural gas in liquefied form for facilitating transportation and storage. government of pakistan intends to bring lng as a substitute to diminish the supply demand gap of cng.[ ]the idea to import lng for pakistan energy sector was firstly proposed in national energy plan. however, idea was not materialized due to ogra rejection and interference of supreme court in fixing the increased prices of cng .[ ] present pakistan qatar government to government lng contract that was dealt by pm abbasi had settled in .the validity period of contract is years with annual . million tons supply of lng. government officials consider the projects of lng as a major breakthrough for energy sector. however, antagonist factions strongly oppose the lng import projects due to high prices and chances of corruption. [ ] the projects of lng are still underway and no final verdict can be made without observing ground realities after inclusion of lng in pakistan energy sector. . . liquefied petroleum gas (lpg) liquefied petroleum gas is another environmental friendly fuel source. the use of lpg in areas where wood is used as fuel source also decreases the rate of deforestation. lpg is mainly used in residential, automotive and commercial sector. although the contribution of lpg in pakistan power mix is relatively low . kg per capita .[ ] however, the consumption of lpg in world is high with usa, mexico and japan as energy scenario and diversity in pakistan: an energy security perspective major consumer states [ ] in pakistan lpg is mostly used in ruler areas where natural gas is not accessible. the progress in lpg sector is very slow with around only ten of lpg producers. the few producers results in low market competition and thus formation of cartel. [ ]the lpg cartel monopolizes the market that results in high prices of lpg. pakistan is leading south asian countries with highest lpg rates in region. the major consumer of lpg in pakistan is mainly households. however, the high prices of lpg leave no options for low income citizens but resort to the option of cutting of forests for fuel. . . coal pakistan is blessed with plentiful coal endowments. the country has proven coal reserves of billion tons .out of which tremendous reserves of billion are in the thar region .the history of coal as a fuel source can be traced back to industrial revolution. the contribution of coal in success of industrial revolution cannot be denied. [ ] coal is still utilizes as a major source for power generation in many european countries. almost percent of world electricity is generated from coal. china produces percent of its electric power from coal while india generates percent of power from coal. however, in pakistan the use of coal as power generation source is negligible. pakistan’s thar coal is renowned from four decades but its share in energy is negligible. there are three pre conditions to check the viability of energy source, its affordability, its accessibility and its capability for continuous supply. pakistan’s coal reserves fulfill this criterion of sustainability. pakistan’s coal despite meeting the criteria is playing a negligible role in total energy mix. [ ] according to energy security plan of pakistan will generate mw by utilizing thar coal. today coal is widely deplored due to environmental considerations. however, it is still used as a major source of electricity generation in world .pakistan’s coal is still not properly utilized in energy scarce county. the reason is high infrastructural cost, lack of technological availability and specialty, political discontentment and crisis of skilled human resource. pakistan has started work with cooperation of china under cpec projects. but the dilemma is that pakistan is importing coal for most of its coal power projects rather than utilizing its indigenous coal reserves. the transformation from imported oil to imported coal will not resolve pakistan’s balance of payment issue. pakistan should keep in mind increase in price of coal from usd to per ton when oil prices hiked in and slapping taxes imposed by india and indonesia on coal export prices .there are some myth attached with thar coal that it cannot be transported due to high combustion volatility. however same coal is transported in india to distances of hundreds kms. pakistan is still using conventional method of shovel and truck for coal mining that takes more time and energy. currently two coal power plants installed outside thar are enough to meet instant need others projects should be installed in thar. pakistan must use indigenous coal for achieving energy security in energy scarce country. the import of coal when country own coal is equivalent to oil reserves of iran and saudi arabia is nothing but drawback in policy formulation. the vast deposits of thar coal can be utilized by exporting coal to india it can be exported to indian rajistan region that is adjacent to thar region of pakistan. pakistan can also get expertise from india to utilize thar coal as india has great experience in power generation from coal and third unique option can be revival of barter economy that will serve the interests of both states. pakistan provides coal to india and india in return provides electricity to pakistan by placing coal based power plants in its border areas. [ ] . . renewable sources of energy the change of millennia has also changed the conventional sources of acquiring energy. the worldwide increasing demand of energy has increased the gap between demand and supply of energy. the excessive use of expensive thermal sources, rapid pace depletion of these sources and environmental considerations attached with them forced the world to explore sustainable and reliable sources for energy generation .therefore globally there is worldwide increasing trend to adopt renewable energy sources for fulfilling energy demand. however, pakistan energy mix is still in favor of thermal to great extent. [ ] the share of renewable is only . percent in pakistan’s energy mix. . . hydel pakistan has potential of generation of , mw of electricity from hydel sources. however the current installed hydel capacity is of mw only. according to the data provided in energy yearbook ( ) share of hydel in pakistan energy mix is . percent. whilst the share of hydel in s was about - percent .pakistan suffers heavily from overflowing rivers in every moon soon season. these overflowing rivers can play a role of blessing in disguise if country uses proper mechanism. the construction of dams can not only rescue country from floods it can also produce adequate energy to overcome electricity shortfall. [ ] this region has the option of exploiting water reserves flowing from arabian sea to himalayas. pakistan in early years of its independence used the potential of hydel power for fulfilling its energy demand. mangla was first major developmental project that was completed in with capacity of generating mw. subsequently tarbela with capacity of , had been completed in . ghazi barotha was another advances in energy and power ( ): - , development with capacity of , mw. however, after these three major developments the unfortunate era of politicization of water started that halted further progress in hydel energy. [ ] the controversy and conflicts over kala bagh dam halted development in other hydel power projects also. however, in recent years some progress had been made in hydel power projects. the work on various projects has been started and many of these projects are estimated to be completed in . chairman wapda in an interview to anchor kamran shaid in programme on the front at dunya news gave the deadline for completion of nelum jhelum hydel power project in somewhere between may to july . he considered nelum jhelum with capacity of megawatt as major breakthrough in energy mix and he determined this project with other projects that will be completed in will end load shedding in country. . . nuclear source of energy the use of nuclear energy for generating power was started in s.today there are around nuclear reactors operating in world with combine capacity of , mw. pakistan generates around , mw electricity from nuclear sources .[ ] currently there are four nuclear power plants (chashnupp- , chashnupp , chashnupp and kanupp ) operating in country. the work on kanupp- , kanupp- and chashnupp - is in progress. [ ] the contribution of nuclear in pakistan energy mix during fy was . % only (energy year book ). pakistan atomic energy commission (paec) aimed to enhance it to mw till . nuclear is viable option for energy deficient country like pakistan. as one pound of uranium can substitute , , of oil gallons, natural gas of around , , cubic feet and , tons of coal. pakistan is strictly observing the bindings of iaea for its nuclear power generation. [ ] it has also applied for nuclear supplier group (nsg) membership that can help pakistan remarkably in increasing the share of nuclear in its energy mix. . . solar energy pakistan is blessed with plentiful solar energy with availability of sun around days in year. [ ] however the contribution of solar in pakistan’s current energy mix is meager. solar is sustainable, clean, reliable and all of above indigenously available option for pakistan increasing energy demand. for plenty of reasons exploiting solar energy is suitable option for overcoming energy crisis in pakistan. a large number of our population lives in rural areas where electricity is not available. to provide electricity through national grid lines to these villages will, need long term planning, development of infrastructure and large-scale investment. however, to provide them solar panel will be a more feasible option. in most of villages where natural gas is not available people use wood as a fuel source. the use of solar cooker for cooking can control increasing deforestation rate. the solar energy can be best utilize in rural areas of sindh and baluchistan. in most of villages where electricity is not available and people live in one room house. their energy demand is maximum watt that can be best served by using solar power. [ ] the solar power plants of - megawatts are spread throughout the state. although development towards solar is slow but it can get better in future with more efforts and efficiency. . . wind pakistan is capable of generating , mw of energy from wind. the combine capacity of solar and wind can generate , mw of electricity. currently pakistan has installed wind energy capacity of mw. different researchers indicate pakistan has best corridors of wind in regions of thatta, islamabad and karachi. the installation of wind turbines in these areas can mitigate the energy deficiency of pakistan. wind is environmental friendly source of energy. many countries in world including our neighbor state india are making the best use of it. pakistan is also ambitious to increase the share of wind energy in its energy mix. however, progress on ground is very slow but it can be improved by installing more wind turbines in its perfect wind corridors. [ ] . challenges of pakistan’s power sector pakistan is facing protracted energy crisis that not only jeopardize country’s economy but also haul sustainable development. the shortfall of energy is due to shortfall in governance and shortfall in political will rather than a shortfall of supply. [ ] . . fragmented governance structure the fragmented governance structure of pakistan’s energy sector itself is a major challenge. this fragmented institutional structure and absence of cohesive body to deal with energy issues slow down the policy implementation process as well as it incurs additional transaction cost. [ ] currently there are six ministries and agencies working for energy developmental projects in country. each entity is working under its own term of reference (tor) and strategies. the absence of a united body and lack of coordination among these governing entities at different level makes the sector dysfunctional. moreover, the political appointments rather than prioritizing experts and professionals on important positions in energy deficient country is also a serious concern and major cause energy scenario and diversity in pakistan: an energy security perspective of consistent energy crisis. . . inefficient regulatory framework the two regulatory authorities of energy sector have been put under ministerial control in june . nepra has been placed under the command of water and power division and ogra has been placed under the command of petroleum and natural resource division. [ ] the aim of formulating regulatory bodies for energy sector was to improve efficiency and serving investors and customer interest independently. however, these regulatory authorities are working in highly centralized manner under considerable political influence on pricing and tariffs. the pricing and tariffs related decisions of these regulatory authorities need approval of government. the organogram of nepra consist of a chairman and one member from each province; all these crucial appointments are made by government where political affiliation is preferred rather than expertise. due to delays in appointment sometime nepra works in absence of chairman ( - ) and sometimes it works without members ( ). [ ] . hence both regulatory authorities nepra and ogra face shortage of professional capacity to monitor regulatory framework efficiently. moreover, the lack of collaboration between ogra and nepra also creates disharmony in pricing of electricity and gas that gives inconspicuous message to investors. [ ] . . federal – provincial issues on energy sector the harmony between federating units and center is important for the national development as well as for fostering sectoral performance. unfortunately, pakistan since its inception is facing tensions between center and provinces over various issues. even after the th amendment in constitution the tension between center and provinces persist in one form or another. the center-province tension over energy related issues is ongoing. mostly the tension is over the issues of hydroelectric projects or resource distribution and provinces demand for due share. the provincial grievance over kalabagh dam is a prime example in this regard. therefore, it is necessary to take certain measures for resolving center-province issues for smooth operation of power projects. . . independent power producers (ipps) the major policy decision of introducing ipps in energy sector although inexorable but induced considerable implications on power sector. the prices of power raised and pakistan energy mix shifted highly in favor of oil. the rise in electricity price was not only due to excessive use of oil for power generation but due to inexpedient agreements. these imprudently signed agreements not only allowed ipps to set high tariffs but also provided them inessential guarantees. [ ] resultantly to manage increasing prices government subsidized the tariff for certain consumers that resulted in other financial issues. . . transmission and distribution losses the power generated in power house reaches to end users through different transmission and distribution lines, cables and transformers. when electricity generated in power station doesn’t match with electricity reached to end users that difference between the generation and distribution is called transmission and distribution loss.[ ] it is estimated that t&d loss of one percent incurs deficit of one billion over national treasury. however, pakistan ranks out of countries of world in t&d losses. these t& d losses are either technical or non- technical/commercial. technical issues include outdated technology, leakage, inefficiency in transmission and flawed planning plus poor design of network of distribution. non-technical issues include corruption, pilferage, illegitimate connections, defective meters and non- payment of electric bills. both technical and non-technical issues arise due to maladministration and poor governance. pesco and sepco have shown poor performance in t&d losses with reported losses of . and . percent respectively. the performance of other distributive companies is also disappointing. the only option left to reduce these line losses is to disconnect the transformers where unidentifiable defaulters found. [ ] there is dire need of taking urgent measures to control these losses. otherwise it will bring devastating consequences for already deteriorating energy sector. . . undue subsidies the imbalance between electricity price per unit and per unit cost of supply indicates the level of subsidy. pakistan’s government pay subsidies in billions for electric power consumer, consequently it is indebted in billions of circular debt. the objective behind providing subsidy on electricity tariff was to increase lifeline (indigent) consumer capacity of paying electricity bills. pakistan adopted the incremental block tariff (ibt) strategy for poor consumers. in block tariff pricing the charges of electricity increase with the increase in use of unit. in ibt if a consumer pay . rs per kwh for the first kwh, then it will charge . rs until kwh, then . till kwh and after this limit it will charge . for the levels above. there is an unreasonable tariff of rs for minimum use of electricity that obviously affect the poor household who uses electricity only for lightening house. despite paying heavy subsidies for helping the poor households, the major portion of these subsidies benefits richest households in country. the direct transfer system as in benazir income support programme can be more cost effective and specific in achieving the advances in energy and power ( ): - , target.[ ] there is need to introduce effective policy options for achieving target otherwise pakistan will not ever able to get rid of energy crisis. . . the problem of circular debt circular debt chain starts from electricity consumers who don’t pay their electricity bills and ends at government nonpayment of money to power sector entities.[ ] when government withholds the payment of an entity in turn it withholds the due payment to next actor in chain and so on. this is the whole story of circulating circular debt of pakistan’s power sector. although in government claimed that they cleared the debt of billion rupees. however, presently pakistan’s circular debt has reached beyond billion rupees compare to billion rupees about a year ago.[ ] some analysts are of the view that circular debt actually is a real monster behind the energy crisis .other believes that maladministration, bad governance and corruption are more important. the inefficient governance is responsible for circular debt from corporate to sector level. the ineffective government policies, failure to recover t&d losses, overstaffing rather than few and specialized task force , delays in payments, inefficiency in collection of revenue , delays in determining tariff and inappropriate allocation of subsidies are issues of paramount importance that are responsible for lingered circular debt in country .[ ] the prerequisite to resolve energy crisis is to address the issue of circular debt on a war footing. . policy issues . . overambitious and ambiguous policy in policy making process one need to be realistic and don’t need to be ambitious. there is no need to give policy with tall objectives and tall promises. when these promises not achieve then policy lead to the failure. therefore, the failure policy either leads to termination or work as failed policy. termination of policy is costly step for the government to take. because, there are a lot of stakes of resources, jobs and institutions. when policy is not able to be modify due to lack of skill analysis or need analysis then these things effects power sector badly. there exists information gap between policy planners and society which results in bad policy decisions. when policies are devised by people who are unable to understand the demands and needs of the policy subjects then in result inefficient and ambiguous policy comes in effect.[ ] moreover, the overambitious nature of the policies without evaluating the resource affordability and societal structure make the policy fail to attain desired outcomes. if a policy comes that is not implementable which is apart from ground realities or practical situation. a policy which is not corresponding to the capacity of implementers, of the bureaucracy, of the administrative machinery and of the resources. it means that something is wrong with that policy formulation. . . poor governance structure the poor governance structure, maladministration and corruption hamper the implementation of policies. the major reason behind poor governance structure is lack of collaboration to achieve certain policy objectives. the lack of collaboration among centre and provinces and among provinces and localities hinders the policy implementation process.[ ]the success of energy policies depends on the joint efforts of all actors at centre, provincial and local level. the issue of corruption and maladministration also hamper the policy implementation process as the office holders put the national interests at stake and keep their self-interest on priority. . . lack of resources for the success of any policy the availability of resources is very crucial whether it is technical, financial or human resource.[ ]the lack of resources is major hindrance in power policies of pakistan. all the policies are well formulated and desire to achieve the energy efficiency in country however limited resources mitigate the success rate of these policies. due to the lack of financial resource there is inadequate infrastructural development and inability to solve the circular debt issue of pakistan. the scarcity of technical and human resource hinders the developmental process for attaining progress. moreover, the misuse of resources is also alarming like appointing a misfit person at higher position effects the formulation and implementation of policy .the person without relevant expertise and experience cannot tackle the policy issues like an experienced and expert one. the misuse of financial resources leads to corruption and fraud cases which again badly effect the implementation of policy decisions. . . lack of political will and interest the interest and will of ruling body is necessary for any developmental project. in pakistan national politics has become a blame game where every party is blaming other for inefficiency and incompetency. the political economy of formulating policy has become vote oriented rather than welfare oriented policies.[ ] the public representatives are more inclined to increase their vote bank rather than initiating and supporting long term public welfare programs. in pakistan another policy dilemma is that every new elected government discontinues the policies and projects of the previous governments. the political parties tends to introduce policies that bring more benefits for their favorites and increase the chances for them to be re -elected. energy scenario and diversity in pakistan: an energy security perspective [ ] this lack of will and interest of political representatives bring difficulties in attaining the power policy goals. that’s why today pakistan is facing grave crisis of energy that is worsening on every coming day. . policy options for pakistan . . diversification of energy mix pakistan is heavily reliant on imported energy sources specifically oil for fulfilling most of its energy demand. the rapid depletion of these traditional energy sources and pakistan own economic condition demand the diversification of its energy mix. there is instant need to expedite diversification process for economic sustainability and societal progression. otherwise, pakistan will remain far behind in world of rapidly growing economies. . . utilization of indigenous sources of energy unfortunately, pakistan is energy deficient country but despite having sufficient natural endowments. it is blessed with enough resources to generate its own energy for fulfilling the energy demand of its population. coal is still use as a major source of power generation in world and pakistan has the estimated coal reserves of billion tons lying dormant. furthermore, the renewable power generation capability of pakistan is also enough for satisfying the demand. the exploration of oil and gas plus utilization of coal and available renewable sources of energy have not only capacity of fulfilling the demand, but have capability to produce excessive energy for pakistan. the utilization of domestic sources of energy was the major focus of power policy . however due to gaps in implementation pakistan failed to achieve this goal. as the coal use for power projects is mostly imported regardless of vast coal reserves in country. the transformation from imported oil to imported coal will not resolve pakistan balance of payment issue. pakistan should keep in mind increase in price of coal from usd to per ton when oil prices hiked in and slapping taxes imposed by india and indonesia on coal export prices. the vast deposits of thar coal can be utilized by exporting coal to india it can be exported to indian rajistan region that is adjacent to thar region of pakistan. pakistan can also get expertise from india to utilize thar coal as india has great experience in power generation from coal and another unique option can be revival of barter economy that will serve the interests of both states. pakistan can provide coal to india and india in return can provide electricity to pakistan by placing coal-based power plants in its border areas. [ ] there is dire need to exploit the available renewable energy sources for overcoming the energy crisis and environmental degradation. the whole world is not only supporting renewable but major powers are also providing funds for development of renewable projects. pakistan can utilize hydel, solar, wind, and biomass sources for producing renewable energy. pakistan can encourage the use of renewable by providing feed in tariffs and incentives on starting a renewable energy project. hydel is the cheapest source of energy for pakistan. in short run pakistan can start mini hydro projects for electrifying the villages and small communities. in long run it is needed to construct the dams by resolving all the federal –provinces differences and discontentment. for plenty of reasons exploiting solar energy is suitable option for overcoming energy crisis in pakistan. a large number of our population lives in rural areas where electricity is not available. to provide electricity through national grid lines to these villages will need long term planning, development of infrastructure and large-scale investment. however, to provide them solar panel will be a more feasible option. the solar energy can be best utilized in rural areas of sindh and baluchistan. in most of villages where electricity is not available and people lives in one room house. their energy demand is maximum watt that can be best served by using solar power. [ ] . . energy conservation the growing energy consumption, depleting energy resources and escalating energy crisis demand the conservation of energy. it is the duty of government and citizens to promote energy conservation culture. in pakistan the trend of wearing three piece suits in chilled rooms have become popular regardless of outside temperature may cross degree. there is dire need to start public awareness campaigns for conservation of energy. the promotion of energy efficient devices like air conditioners, energy saving bulbs, ovens, washing machine etc. is required. furthermore, the labeling of energy consuming devices can also contribute in bringing energy efficiency. [ ] however, it is not always money that makes sense but to motivate people socially and religiously can bring more impressive outcomes. to aware people religiously many ahadits and ayahs of quran can be quoted where extravagance is condemned either it is money, food, water or any other thing. quran says: the spendthrifts are the brothers of the shayatin and the shaitan is ever ungrateful to his lord. (al quran, surah isra, verse ). moreover, there are number of social campaigns in world that were targeted to bring energy efficiency by promoting energy conservation culture. the go cold turkey campaign targeted students and drive them to make promise that they will turn off the unnecessary electronic appliances. then there are numerous campaigns launched in korea for energy conservation that were very success. advances in energy and power ( ): - , [ ] pakistan can also start these sorts of campaigns to bring awareness in public to promote the culture of energy conservation. universities and think tanks can play an effective role in developing an energy conservation culture. . . economic options the energy crisis of pakistan and the connected issue of circular debt are aggravated since last few years. pakistan’s circular debt has reached beyond billion rupees compare to billion rupees about a year ago. [ ] the inefficiencies in collection of bills, expensive fuel and government inability to pay subsidies have escalated the circular debt issue. the nonpayment of electricity subsidies is primary cause of circular debt problem. the subsidy system of pakistan is ineffective as it has proved more advantageous for richest segments of society rather than helping the needy and poor. to provide the subsidies to all electricity consumers increases the financial burden of government. thus, replacing subsidy with cash transfer programme like bisp can be more fruitful and financially viable option for pakistan. an example of successfully replacing subsidy with cash transfer is iran. pakistan can learn from iran how it successfully replaced subsidy with the cash transfer programme. [ ] moreover, the nonpayment of electricity bills is another financial obstacle for the sector. pakistan can switch to the key meter and bill meter technology to overcome this issue. the prepaid billing technique can be used for consumers who are irresponsible towards paying their bills and postpaid billing for those who pay their bills regularly. then in long run the induction of smart meters can also help in conserving energy and bringing transparency. it will enable customer to monitor the impacts of their lifestyle on energy consumption. furthermore, it will increase accuracy on both consumer and supplier ends. [ ] . . demand management in pakistan the shortage of electricity is not due to shortage of installed capacity but due to shortfall in generating capacity. pakistan has enough installed capacity to satisfy the electricity demand. the inefficiencies in governance, lack of infrastructure or outdated infrastructure, issue of circular debt, t&d losses are the major cause of power crisis. thus, it is needed to improve governance structure by encouraging merit system and discouraging corruption and inefficiencies. the infrastructural development is mandatory to bring efficiency in power generation and to reduce t&d losses. to make the electricity transmission possible to the end consumer pakistan need automatic metering system (arm) that will eliminate theft and human involvement. on long term it needs renewable energy so that to have sustained and diverse energy mix. . . development of human resource human resource is an important key to development if organize and employ efficiently. it is next to capital and land in factor of production. [ ] however, unfortunately in pakistan the employment of inefficient and irrelevant persons at higher positions has deteriorated the sector performance. furthermore, we lack human resource in engineering of certain projects. thus, it is needed to encourage youth to get education and training in relevant areas by opening the relevant department in various universities. furthermore, we need to say good bye to culture corruption for the sake of bringing efficiency and development. . conclusions the rapid growth in world population, technological innovation and overconsumption of energy has created energy deficiency in the world. today, states are worried for the increasing demand and supply gap of energy. the utilization of indigenous sources is prerequisite to bring energy sufficiency in the country. the over utilization of expensive imported resources has already deteriorated the energy situation. pakistan cannot ever satisfy its energy demand without utilizing the domestic renewable energy resources. the diversification of the energy mix and utilization of indigenous resources is only option remain with pakistan to get rid of lingering energy crisis. the overreliance on expensive imported sources has created balance of payment crisis and circular debt issue in pakistan. moreover, the environmental concern attached with the traditional sources of energy also demands the transformation of the energy mix. globally there is already large-scale diversification towards renewable and indigenous sources of energy. although pakistan has comprehensive set of policies and numerous sectoral entities but still it is unable to resolve the issue of hours long power outages. the energy crisis of pakistan is result of multiple factors. the culture of rent seeking, corruption, poor governance, institutional inefficiency, electricity theft and circular debt are responsible factors for growing energy crisis in pakistan. that’s why despite having enough resources and capacity country is unable to satisfy the energy demand of its population. it is required to resolve these issues instantly to get rid of this anomalous crisis of energy. another major factor of energy crisis is that pakistan didn’t create any awareness to conserve energy. it is not about the price a consumer pay for consuming energy but the point is that they are consuming the energy of other person share. pakistan needs to develop energy conservation culture, a unit saved is much cheaper than a unit generated. so, if that is known by the consumer it will have effect on the usage of energy. on other side the consumption pattern of the electric appliances has been energy scenario and diversity in pakistan: an energy security perspective changed so drastically that now all the appliances at home needs more energy. people should be aware about the advantages of energy efficiency and energy efficient devices labeling of devices is necessary as it will develop more responsible attitude. it is political leadership who has to take this issue on high political agenda to bring it to the top most priority of the country. for individuals in the society to act in this manner and for conservation of energy, from water to electricity and oil, there is need of a comprehensive approach for the massive awareness. it is the duty of each and every person to give their due share in resolving this energy crisis. almost unquestionably, energy has become a serious concern for survival on this blue-green planet. references [ ] faheem, j. b. 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( , october). smart meters in pakistan: a technological perspective. retrieved april , , from https://propakistani.pk/problog/smart-meters-technological perspective/ [ ] hassan, b. . “need for human resource management.” pakistan today, april . https://www.pakistantoday.com.p k/ / / /need-for-human-resource-management/ 	 . introduction 	 . literature review 	 . pakistan’s current energy scenario 	 . challenges of pakistan’s power sector 	 . policy issues 	 . policy options for pakistan 	 . conclusions 	references (jpmnt) journal of process management – new technologies, international vol. , no , . www.japmnt.com the importance of energy for the economy, sustainable development and environmental protection - an economic aspect ljiljana stošić mihajlović, svetlana trajković , high school of applied professional studies, vranje, serbia mihajlovicp@ptt.rs original scientific paper doi: . /jouproman - abstract: in the area of modern economy and environmental protection there are no significant changes: the old problems are not solved, and the existing ones are deepening. humanity is still struggling with three existential problems: lack of food, lack of drinking water and insufficiently energized energy. they are also associated with the dangers of further degradation of the environment, the general fear and fear of terrorism and wars, the emergence of diseases for which modern medicine simply has no solution and which threatens to overcome the challenge of pandemic. energy is still a mood of economic development, with at the same time a disastrous effect on the environment, when traditional sources of fossil resources are used as sources of energy. the paper explores the phenomenon of the impact of energy on the sustainable development of the economy, with a key focus on environmental protection, as well as the possibilities for adaptation to mitigate the consequences of this global phenomenon. in this regard, special attention has been devoted to researching the role and significance of energy from renewable sources as a possible response to current or expected climate stimuli or their consequences in natural and humanism systems. particular emphasis is placed on the principle of adaptation, which includes mitigation of damages or the exploitation of effective opportunities; understanding how climate can change, what can be impacts, and capacity building and action on these impacts. key words: energy, sustainable development, environmental protection. introduction the biggest task of today with which mankind will fight for the next years is solving problems related to energy, water, food, endangered environment, poverty, terrorism and wars, diseases, education, democracy, population ( - . billion, estimates - - billion). the growth of the world's population is conditioned by the growth of the energy demand, which, alas, today, predominantly products from fossil sources: coal, oil and gas. by , global energy demand is expected to exceed the current demand by as much as %! (stošić mihajlović, lj , page ) in addition, limited reserves of fossil fuels, increase in research costs and climate threats from greenhouse gases and co , is imposed as a global limitation. it is noteworthy that in the next years energy will be the main problem facing all countries in the world, especially the poor countries, which strive for accelerated economic prosperity, which means opening up new production capacities and new investments, require a higher amount of energy that can not be satisfied from domestic sources. klimate as a resource climate is a basic natural resource, from which depends the energy potential of every cabbage and therefore has a dominant influence on ecosystems, as well as on the state and development of society and human civilization in general. according to the global climate change impact assessment (ipcc, and eea, ), the areas of central and eastern europe will be characterized by: more temperature extremes, less precipitation during the summer, more river floods during winter, higher water temperatures, variability in the yield of cereals, a greater risk of forest fires and a lower stability of forest ecosystems. http://www.japmnt.com/ mailto:mihajlovicp@ptt.rs http://dx.doi.org/ . % fjouproman - (jpmnt) journal of process management – new technologies, international vol. , no , . www.japmnt.com research and scenarios of global climate change indicate the likelihood of more frequent occurrences of storms, extreme heat, increased risk of extinction of species, etc. (ipcc ). climate change on the earth and the ecological crisis have resulted from uncontrolled economic, primarily industrial development, inefficient technologies and excessive use of fossil fuels. pollution of the atmosphere by the gases caused by the so- the "greenhouse effect", the destruction of the ozone layer that protects the earth's living world from excessive radiation, global warming, are all the problems that threaten today's generations, and if such a trend continues, it will endanger the future. scientific reports emphasize that adaptation to these effects will require a good knowledge of socio-economic and natural systems, their vulnerability and vulnerability to climate change, as well as their own adaptation capacity. a major global problem is the chronic energy crisis. fossil fuel reserves (detected and assumed) are limited and according to forecasts, depending on the type of energy and consumption, it is possible that most will disappear by the middle of this century, when global economic collapse could occur. adding to this the envisaged climate change, it creates an environment for many dramatic consequences, including frequent droughts, lack of drinking water, reduction of agricultural production, the onset of endemic hunger among the poor layers of the population, the occurrence of epidemics, migration of the population in search of water and food, conflicts around limited resources, etc. (nikolić, ). climate change is a global problem, but the consequences will be felt and be of interest at both the regional and local levels. estimates are that these changes will have significant implications for urban areas, given that over % of the world's population and % of europe's population today live in cities, such problems become the cause of increasing interest. the world wildlife fund (wwf, ), more than a decade ago, drew attention to the significant warming of the capital cities across europe. bearing this in mind, strategic projects are being launched in many countries, such as the "adaptation strategies for climate change in the urban environment -asccue" project. in the united kingdom. these projects include preparation for climate change through strategic planning and the conduct of wise ecological, economic and energy policies. an important aspect of this project is to explore the potential of renewable energy resources in adapting to climate change. the degree of exploitation of conventional natural resources, primarily coal and oil, as a source of energy enters the stage when one has to think about their expansion and diversity, in order to adequately respond to the increasing needs of mankind for energy. this equally applies to the problem of population growth, the need for food and water, and civilization progress. solving these problems is not possible without energy, as an important factor of development. classical sources in the future will not be able to resolve all these needs unambiguously. due to the multiple problems caused by the energy crisis, most countries of the world have been obligated by different conventions and declarations that part of the classical energy sources, depending on the possibilities, will be replaced with renewable energy sources (res). with the development of ecological awareness, the use of res in the world takes on significant conditions. in addition to preventing gas emissions, renewable energy can provide energy independence. one of the important tasks of using renewable energy is to enable local consumers greater energy independence and independence, primarily from imports, and then from national and regional energy supplies through large distribution systems. http://www.japmnt.com/ (jpmnt) journal of process management – new technologies, international vol. , no , . www.japmnt.com consequently, at the state level, the countries of the world have committed themselves to alter existing strategies for using energy sources in the direction of greater use of renewable sources through strategies, plans and legislation. “the global economic crisis in a relatively short period of time has led, however, a dramatic fall in the stock market, bringing down share prices and companies which are economic parameters resisted the crisis, but could not resist the psychology of mass spreading panic and fear of investors. it is also shown, and all the multidisciplinary nature of financial markets whose understanding is all the more important to know the theory of the behavior of market participants.” the importance of energy for sustainable development from the economic theory from the time of adam smith and classical economic thought, country, labor and capital, they are considered the main factors of production and the main sources of economic growth. in time, these factors have been added by the organization as the fourth factor, while in recent times added knowledge or intellectual capital. during the development of economic thought and in economic doctrines, the direct and explicit importance of the role of energy as one of the keys to the factors of economic prosperity was not given. energy remains present and recognized in economic theory and practice as an intermediate good while, according to still current models of neoclassical economics, economic growth is attributed to technological progress and knowledge. in economic theory, for a long time, the amount of energy available to a given economy was endogenously ljiljana stosic mihajlovic, functioning of financial and capital markets in modern conditions, (jpmnt) journal of process management – new technologies, international vol. , no. , . pag. , www.japmnt.com determined, of course, under the influence of biophysical and economic constraints (stern and cleveland, , p. ). it is certain that some driving force must enable growth factors, such as land, labor, capital, organization, technology and knowledge in each economic sector and in each process of economic activity, to result in the growth of the domestic product. that's just energy. namely, the process of production (and economic growth as the final resultant) involves the transformation of matter from one form to another, ie the transformation of inputs, ie, raw material in the final product, and this transformation requires energy (cleveland et al., ). energy enables the continuity and long- term nature of the entire economic activity not only as a supplement to standard production inputs, but without it the economy would not be possible at all. according to alam ( ), every business consists of energy flows that are directed towards the production of goods and services. such a focus on energy creates many new assumptions. namely, putting energy into the focus of economic activity identifies the use of energy as an important source of economic growth and the inevitable driving force of all economic activities (stern and cleveland, ). in other words, the economy should be seen as an energy system consisting of energy flows and conversions that culminate precisely in the production of goods and services, and energy as a key source of economic growth, industrialization and urbanization (imran, , p. ). according to the ecological economics, energy is the most important primary factor of production (georgescu-roegen, , ). the profit conflict, which results from natural resources, often leads to a focus on the distribution of wealth instead of its creation, to social struggles, ie, conflict, undemocratic authority and inequality, that is, corruption, political opportunism and bureaucracy. http://www.japmnt.com/ (jpmnt) journal of process management – new technologies, international vol. , no , . www.japmnt.com according to smith ( , p. ), developing countries are often less resource-rich than the current developed countries at the time they began their growth. several developing countries abound in the vast reserves of oil, ore and raw materials that are rising world demand, while many smaller countries (especially in asia) are poorly abundant in natural resources. on the other hand, in parts of latin america and africa (eg mexico, nigeria and venezuela) where natural resources are greater, it is necessary to have a larger, even huge investment of capital for their exploitation, and such financial resources can be obtained by sacrificing a substantial part of the control over natural resources. models related to the phenomenon of the curse of natural resources are known as the so-called. models of the dutch disease models, based on the theory that the increase in the available quantity of one factor with an unchanged amount of the second and unchanged technology will lead to a decline in the production of the product that is more intensively used by the production factor whose the available quantity has not changed. in economic theory, the "dutch disease" is the name for a set of economic consequences that arise with the specialization of the country according to its comparative advantage. (the name was sketched in in the economist to describe the decline of the dutch manufacturing sector following the discovery of natural gas in the country during the s (ebrahim-zadeh, ). ecological economy ecological economics is the term for a "new" or modern economy driven by the concern and interest to solve accumulated global environmental problems. it views the world of nature and society in a very different way from the conventional economy. the ecological economy deals with the review of the excessive use of materials and thermodynamic bases of economic activity, mainly focusing on the inevitable interactions of people and ecosystems in the broadest sense. the ecological economy examines the fundamental relationships between physical and biological systems, the problems of ecosystem management in a sustainable way and the impact of social on ecosystems. it is a link between ecology and economics, and there is also a special and leading scientific discipline of the st century, because in the focus of its research exclusively economy and profit, it already observes the co-operation of economic parameters with regard to quality of life. the ecological economy summarizes other scientific disciplines (not only economic and ecological), in fact it leads to the integration of natural and social sciences, among which a clear border must be revised and deleted. in addition, although natural resources and energy were gaining importance in the neoclassical model of economic growth, this did not satisfy critics of neoclassical growth theory. namely, nicholas georgescu-roegena was the first to point out the lack of energy in economic theory. georgescu-roegen ( , ) pointed out that neoclassical economists abstract natural resources and energy flows, while at the same time ignoring economic residues and waste as a byproduct of economic activity. he found that standard economic theory does not recognize the fact that on one hand energy and material resources are irreversibly spent, while on the other hand the detrimental effects of economic activity on environmental pollution continue to accumulate. perpetuum mobile economic system is simply not possible. the problem arises from the overly optimistic attitude of economists to the endless growth potential based on the endless use of the natural environment and its capacities. this is due to unrealistic optimism based on a limited view of the world that excludes nature, natural capacities and limitations of energy resources (alam, , p. ). http://www.japmnt.com/ (jpmnt) journal of process management – new technologies, international vol. , no , . www.japmnt.com contrary to unrealistic economic optimism, members of the ecological economy advocate the idea that the so-called " physical dimension and environmental capacities condition the possible economic production. in contemporary terrors of economic prosperity, economic systems exchange energy and matter with the environment, so that the economic system must accept as an open thermodynamic system. the eco-economics followers start from the material base in one country and criticize the neoclassical theory because of the failure to locate economic activity within the so-called. physical realities - they perceive the economy as a complex system (ramos-martin, , p. ), as an open subsystem of the global ecosystem. the process of economic production consists of inputs of natural capital, but the total economic activity includes the necessary contents of the ecosystems that enable human life. the ecological economy emphasizes the importance of preserving natural capital as an instrument for creating additional, new values (ayres and warr, ). namely, the global economic system is dependent on four basic biological systems (forests, fisheries, forests and grasslands). according to rifkin ( , p. ), basic biological systems do not only allow available food but also all raw materials for industrial production. this approach to the economic system also implies the absorption of waste as a by-product of economic activity and the preservation of the environment that enables the life and survival of civilization. the influence of energy in sustainable economic development and environment the most important strategic documents of the republic of serbia (strategy for the development of enegetics by with projections until and the national strategy for the sustainable use of natural resources and goods) undoubtedly point to the necessity of promoting greater use of renewable energy sources (but the results so far are still unsatisfactory). in the above-mentioned document, it is unambiguously stated: "all analyzes of key economic and technological changes indicate that in the last two and a half centuries, energy has been the driving force and key factor of economic change, as well as the backbone of economic development. changes that take place globally require a long-term perspective of their impact on the national level and proper management of energy development. " according to directive / / ec, "energy from renewable sources is energy from non-fossil renewable sources, such as: wind energy, solar, aerothermal, geothermal, hydrothermal, ocean energy, hydropower, biomass, landfill, gas from waste treatment plant and biogas . "renewable energy sources and their management is an important issue in all developed countries. "the priority of world development today is the protection of energy supply at affordable prices, but in order to maintain and increase living standards. at the same time, the negative effects of the use of energy on the environment, especially fossil fuels, must be reduced. therefore, the world from year to year redefines energy policy and focuses on the creation of a competitive energy market through the use of renewable energy sources. "(mihajlović-milovanović, z. , page ) a good way to point out the significance and impact energy on the economy and the environment by applying a tabular overview. http://www.japmnt.com/ (jpmnt) journal of process management – new technologies, international vol. , no , . www.japmnt.com table . comparison of energy impacts from different sources on the economy and the environment type of energy resources non renewable energy renewable energy sources variables possibility of storage and transport easy storage in most cases, it is impossible to store and transport consistency easy transport not the size of the investment for the construction of the plant yes high units per unit of power there are no additional costs because there is no purchase of combustion fuels plant and maintenance costs lower investments per unit of power high costs extra for the purchase of a combustible fuel low the effect of "greenhouse gases" high, how life is growing in most cases, there is no impact impact on environmental pollution high not possibility of fast and balanced economic development yes yes all types of renewable energy (hydropower, geothermal energy, biomass energy, solar and eolic energy) are inseparable and therefore need to be used to the maximum, on the one hand, because they are renewable, and on the other hand, it is energy that does not generate waste, does not create pollution does not create problems related to clean air, clean environment and clean water, and does not affect sustainable development. conclusion energy is fundamental to economic development, but at the same time it must be in the function of preserving the environment. only this approach to energy leads to a sustainable energy system, a more efficient economy and greater social well-being, with sustainable balances and capacities of natural resources and as low as possible pollution levels. a new scientific discourse created within the synthesis of social and natural sciences, called the ecological economy, pays due attention to the laws of thermodynamics in the process of economic activity, which ensures economic activity while preserving the environment in a realistic framework of sustainable development. energy management is the way to supporting the reduction of environmental threats and economic costs while increasing the quality of life and economic prosperity. literature . georgescu-roegen, n. ( .). the entropy law and the economic process. harvard university press . imran, k., siddiqui, m.m. ( .): "energy consumption and economic growth: a case study of three saarc countries", european journal of social sciences, ( ): - . . internacional panel for climate change – ipcc, i eea, . mihajlović - milovanović zorana ( ): obnovljivi izvori energije, megatrend univerzitet beograd . nikolić, radovan ( ): Екоnomija prirodnih resursa, Коmpjuter centar d.О.О. bor. . ramos-martin, j., ortega-cerdŅ, m. ( .). "non-linear relationship between energy intensity and economic growth", http://www.rrojasdatabank.info/ thermo/ps p.pdf . rifkin, j. ( .). entropija – novi pogled na svijet. misl, zagreb . stošić mihajlović, ljiljana ( ): obnovljivi izvori energije, vŠpss, vranje . stošić mihajlović, ljiljana ( ) functioning of financial and capital markets in modern conditions, (jpmnt) journal of process management – new technologies, international vol. , no. , . pag. , www.japmnt.com . strategija razvoja energetike republike srbije do . godine sa projekcijama do http://www.japmnt.com/ (jpmnt) journal of process management – new technologies, international vol. , no , . www.japmnt.com . stern, d. ( .). "the role of energy in economic growth", united states association for energy economics and international association for energy economics, working paper no. - , november , http://ssrn.com/abstract= (pregledano . listopada . godine). . cleveland, c.j. et al. ( .). "natural capital, human capital and sustainable economic growth",http://www.bu.edu/cees/research/ workingp/pdfs/ . http://www.ipcc.ch/publications_and_data/ ar /syr/en/contents.html . http://cmp- openstandards.org/guidance/wwf- conceptual-models/ . http://climate- adapt.eea.europa.eu/metadata/projects/ada ptation-strategies-for-climate-change-in- the-urban-environment . http://eur-lex.europa.eu/legal- content/en/all/?uri=celex% a l http://www.japmnt.com/ http://www.ipcc.ch/publications_and_data/ar /syr/en/contents.html http://www.ipcc.ch/publications_and_data/ar /syr/en/contents.html http://cmp-openstandards.org/guidance/wwf-conceptual-models/ http://cmp-openstandards.org/guidance/wwf-conceptual-models/ http://cmp-openstandards.org/guidance/wwf-conceptual-models/ http://climate-adapt.eea.europa.eu/metadata/projects/adaptation-strategies-for-climate-change-in-the-urban-environment http://climate-adapt.eea.europa.eu/metadata/projects/adaptation-strategies-for-climate-change-in-the-urban-environment http://climate-adapt.eea.europa.eu/metadata/projects/adaptation-strategies-for-climate-change-in-the-urban-environment http://climate-adapt.eea.europa.eu/metadata/projects/adaptation-strategies-for-climate-change-in-the-urban-environment open access model of water, energy and waste management for development of eco-innovation park ; a case study of center for research of science and technology “puspiptek,” south tangerang city, indonesia† sri setiawati *, hadi alikodra , bambang pramudya , and arya hadi dharmawan bogor agricultural university, the ministry of research and technology the republic of indonesia , bogor agricultural university . introduction . background abstract concept of sustainable development must be trans- lated into concrete measures in the form of policies, programs and activities carried out jointly by the government, private sector and society at large. various models of synergy between economic and environmental concept is growing in almost all †this work is a part of a dissertation submitted for doctoral degree of corresponding author at graduate school of bogor agricultural university (ipb). *correspondence to : sri setiawati graduate school of bogor agricultural university (ipb) director of s&t supply-demand network, the ministry of research and technology, republic of indonesia e-mail : asdep @yahoo.com world technopolis review copyright©world technopolis association this is an open-access article distributed under the terms of the creative commons attri- bution non-commercial license(http://creativecommons.org/licenses/by-nc/ . ) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited abstract : center for research of science and technology (“puspiptek”) has hectares land area, still maintained as a green area with more than % green space. there are centers for research and testing technology, technology-based industries, and as well as public supporting facilities in puspiptek area. based on the concepts developed to make this area as an ecological region, puspiptek can be seen as a model of eco-innovation. the purpose of this research is to develop a model of water, energy and waste management with eco-innovation concept. as a new approach in addressing environmental degradation and maintaining the sustainability of ecosystem, studies related to eco-innovation policy that com- bines the management of water, energy and waste in the region has not been done. in order to achieve the objectives of the research, a series of techniques for collecting data on puspiptek existing conditions will be carried out, which includes utilities data (water, electricity, sewage) and master plan of this area. the savings over the implementation of the concept of eco-innovation in water, energy, and waste management were calculated and analyzed using quatitative methods. the amount of cost savings and feasibility were then calculated. eco innovation in water management among other innovations include the provision of alternative sourc- es of water, overflow of rain water and water environments utilization, and use of gravity to replace the pumping function. eco-innovation in energy management innovations include the use of led and solar cell for air conditioning. eco-innovation in waste management includes methods of composting for organic waste management. the research results: ( ) the savings that can be achieved with the implementation of eco innovation in the water management is rp. , , daily, or rp. , , , annually; ( ) the savings derived from the implementation of eco innovation through replacement of central ac to ac libr solar powered will be saved rp. , , , annually and the use of led lights in the public street lighting puspiptek saved rp. , , annually; ( ) application of eco innovation in waste management will be able to raise awareness of the environment by sorting organic, inorganic and plastic waste. composting and plastic waste obtained from the sale revenue of rp. , , per year; ( ) overall, implementation of the eco-innovation system in puspiptek area can saves rp. , , , per year, compared to the existing sys- tem; and ( )the savings are obtained with implementation of eco-innovation is considered as income. analysis of the feasibility of the imple- mentation of eco-innovation in water, energy, and waste management in puspiptek give npv at a % discount factor in rp. , , , ; . % of irr and . years of pbp. thus the model of eco-innovation in the area puspiptek is feasible to implement. keywords: eco-innovation, policy development, science park wtr ; : - http://dx.doi.org/ . /wtr . . . copyright©world technopolis association article article countries as a model of eco-development, eco-efficiency, cleaner production, eco-industrial areas as well as regional de- velopment model of eco-innovation. in general these models aim to integrate the economic interests on the one side with protecting the environment on the other side. as a new concept, eco-innovation model is exclusive, be- cuse it is not only related to the technical aspects of the envi- ronment, but also it includes the realm of management, policy and social innovation. the concept of eco-innovation by oecd ( ) is “the creation or adoption of new, or signifi- cantly improved products (goods and services), processes, marketing methods, organizational and institutional struc- tures, as well as rules aimed at keeping the environmental im- provement as compared to alternative relevant”. sarkar ( ) concluded that the various definitions that developed the con- cept of eco-innovation can be divided into two categories: non-environmental innovation and environmental innovation. in terms of development, sustainable environment innovation becomes very important. this concept can also be classified into: eco-technology innovation, eco-innovation organization, innovation related to the business district and social innova- tion. at the meso level, the eco-industrial park can also be re- ferred to as eco-innovation park. sakr et al. ( ) stated that the critical success factors of eco-industries park around the world are covering partnership relationship, economic value added, policies and regulations, awareness and information, establishment of institutional and organizational, and technical factors. andersen ( ) makes classification of eco-innova- tion into categories as follows: add-on innovation, integrated innovation, eco-efficient technological system, eco-organiza- tional system and general purpose eco-efficient innovations. therefore, the study of water, energy and waste are based on the add-on innovation category. the product of technology in this study comes from and has been developed by researchers in puspiptek. center for research of science and technology “pus- piptek” is a national strategic area that has tremendous po- tential for the development of science and technology, economic, social and environmental. the growing develop- ment of south tangerang city includes the expansion of resi- dential areas, industrial and office growth, and these development areas will bring tremendous consequences to changes in land use, the environment, biodiversity and so- cio-cultural systems. the model of policy for development of puspiptek eco-innovation area is a model of an integrated policy covering the management of water, energy and waste, regional management model and the institutional model with the concept of eco-innovation that puspiptek area will be an integrated sustainable science and technology area. . research objectives the purpose of this research is to build a model of policy for eco-innovation development in the puspiptek area. the spe- cific objectives are: . knowing the existing condition of water, energy and waste management at the puspiptek area. . develop a submodel of water, energy and waste manage- ment to the eco-innovationconcept. the model of policy is expected to help policy makers (cen- tral and local government), actors of science and technology, industries and other parties who are interested in the eco-in- novation development in puspiptek. . novelty of research research on specific areas of center for research of science and technology as well as national vital and strategic objects have a very high complexity in the management area that needs to be formulated in an integrated system. in the region there is a research nuclear reactor, research centers for physics, chemis- try, biotechnology and others. those require an integrated envi- ronmental management policy in order to provide security and comfort for the people who are inside and outside the region. the research model of policy for eco-innovation in puspiptek region has never been done. therefore, from aspect of the con- cept approach and location, this research has a novelty. a model of policy for eco-innovation development in pus- piptek with the eco-innovation of water, energy and waste management is the novelty of this research. . research methodology . framework as a center for research of science and technology, every stage of its activity in puspiptek requires lots of high quality of material, energy and water resources. meanwhile, pus- copyright©world technopolis association wtr ; : - http://dx.doi.org/ . /wtr . . . piptek still used conventional method to provide energy, water and other material, in order to fulfill the need of labo- ratory and utility areas until recently. if this condition is con- tinued, it will threathen the future activities in puspiptek. for example, puspiptek is very dependent on cisadane river as a resource for water, however the status of cisadane river is worsening due to the river becoming polluted. in addition, the process of research and technology development at the same time generates solid and liquid waste or hazardous ma- terials. therefore, to sustain overall activities in puspiptek, there is a need to develop policy to preserve the environmen- tal and synergy with development activities in the area of puspiptek by designing sustainable ecology through innova- tion. . place and time of research the research model of policy fordevelopment eco-innova- tion park is in the science & technology research center (puspiptek), south tangerang city. this study was con- ducted in june to december . . data processing techniques . data processing techniques were performed with the fol- lowing stages: (i) analysis of water management by calcu- lating quantitative of water management with eco innovation, (ii) determining of infrastructure investment based on eco-infrastructure concept, including the provi- sion of alternative sources of water from the overflow of rain water, (iii) calculating water treatment cost savings by using innovation in the process production of water drainage via gravity process without the use of pumps; (iv) analysing financial water management based on eco innovation. in addition to the above stages, the analysis of eco energy management innovations, which includes quantitative calculation of energy use and the use of led lights with ac with solar cell; is also necessary. this can be calculated for saving the cost based on energy manage- ment efficiency. . analysis of the eco-innovation of waste management, which includes domestic waste, by composting method for organic waste and waste management feasibility of composting techniques. . results and discussion . analysis submodel eco-innovation of water manage- ment water is a part of the natural resources controlled by the state and used for the welfare of the people in a sustainable manner, as set forth in article on paragraph of the indone- sian constitution. the republic of indonesian ( ) con- firms that earth, water and air space, including natural resources contained within the territory of the republic of indonesia are gifts of god almighty and national treasures. the water resources for multipurpose benefits welfare of the entire people in all areas of social, economic, cultural, politi- cal, and national security fields. definition of conservation of water resources is an effort to maintain the existence and continuity of the state, the nature and function of water re- sources in order to be always available in sufficient quantity and quality to meet the needs of living things, both at present and in the future. water conservation can be interpreted as efforts to increase the amount of ground water that goes into the ground and to create efficient water use. each treatment given on a piece of land will affect the water system at the site and downstream areas. soil and water conservation are two things that are very closely related, so it may be said that the various soil conserva- tion measures are also water conservation measures (arsyad ). the eco-innovation concept in water management at pus- piptek is to create the ponds (“embung”) as a water source outside cisadane used today. ponds also serve as a rainwater. water from the ponds flows by gravity to the piping system to the water treatment facility. this model provides cost savings compared to the drainage of water from the river cisadane using an electric pump. data of the water processing in pus- piptek currently is presented in <table > below. the exis- tence of ponds in the puspiptek area presented in <fig. > below. the feedstock of water is assumed to be % of the total requirement based on green building council indonesia (gbci ) criteria for achieving platinum grade. in this sce- nario, the investment that needs to be calculated is the addi- tion of an area of ponds, water channeling investment from the ponds to the water treatment plant by gravity. investment costs required of rp. , , , are presented in <table > below. copyright©world technopolis association sri setiawati, hadi alikodra, bambang pramudya, and arya hadi dharmawan, wtr ( ): article copyright©world technopolis association table . data of the water processing in puspiptek table . investments and expenses necessary for the substitution of % water of the total requirement water treatment data value unit water produced , m /month processing time day capacity per day , m rain water availability rainfall . mm/year rain broad area of buildings , , m the volume of rainwater , , m /year assumption of % of rain water can be discharged into ponds , , m /year ponds evapora- tion and absorption factor of % , , m /year the availability of water in the ponds , , m /year , m /day ponds (“embung”) capacity total area of ponds in housing and other areas , m the depth of water in the ponds m ponds capacity , m substitutionof water feedstock scenario value unit percentage to get a value of points on the gbci assess- ment % substitution capavity , m /month , m /day equivalent of water capacity in the ponds day ponds capacity necessary , m additional ponds capacity , m addition areas , m investments for water distribu- tion from ponds to the water treatment facility - - line : from ponds in the puspitek area to guest house , m line : from ponds in the housing area to guest house , m excavation ponds , m work stages value unit unit cost (rp) excavation ponds , m , excavation line m , excavation line m , installation of u x cm concrete line , m , installation of u x cm concrete line , m , mobilization, demobiliza- tion& cleaning process lot , , , total investments (rp): , , , source: analysis of survey results fig. . slope maps and existing ponds location in puspiptek existing ponds wtr ; : - http://dx.doi.org/ . /wtr . . . the cost savings derived from electricity for pumping and chemical costs. the calculation saving that can be achieved is presented in <table > below. the savings that can be achieved with the implementation of the eco-innovation water management per day is rp. , , or rp. , , , per year. similar funding has been found; zaenuri ( ) con- cluded that by implementing water management in farmacyti- cal industry has been generating cost efficiency . % per a year. . analysis submodel eco-innovation energy manage- ment the issue of energy crisis and global warming have become the attention of the whole world. various technologies and innovations are being developed to find a solution. in addition to finding alternative energy sources that are environmentally friendly, energy saving is being done to reduce the rate of en- ergy consumption. solution of energy crisis is not only coming from in terms of alternative energy production, but in terms of consumption. electricity consumption in buildings is most used by the air cooling system. the conventional air-conditioning (ac) con- sumes relatively very large energy, and requires a large electric power. in indonesia, the majority of electricity is generated through the use of fossil fuels, so the use of conventional air conditioning has impact on the increase in greenhouse gas emissions. furthermore, because the ambient temperature gets hotter, more and more industries, houses, and buildings use ac, thus causing the cycle of environmental destruction and the energy crisis continues. however, inhibition of the use of air conditioning is impos- sible. therefore, it is necessary that the air conditioner innova- tions use renewable energy sources, and eco-friendly, one of which is conditioned by solar power. air conditioning with solar power using solar thermal cooling system cools the room by using the heat of the sun. in such systems, the boiling point of fluid is achieved by thermal compression (akbar ). to replace the compressor in a conventional refrigeration system, three components are used in the absorption cycle, i.e. absorber, pumps, and generators. absorber is used to ab- sorb the refrigerant vapor into the absorbent, so the two are mixed into a solution. the fluid used is water with libr (lith- ium bromide). water and libr is used because they meet the criteria of the working fluid (a mixture of refrigerant and ab- sorbent), namely : ) the different boiling point between the refrigerant and the solution at the same great pressure. ) refrigerant has a high heat of vaporization and high con- centration in the absorbent solution to suppress the cir- culation rate between the absorber and generator per-unit cooling capacity. ) having good transport properties, such as viscosity, ther- mal conductivity, and diffusion coefficient. they can gen- erate good heat and mass transfer. ) both refrigerant and absorbent are non-corrosive, envi- ronmentally friendly, and inexpensive. if the sun is not hot enough, it can also be backed up with a gas heater. ursula eicker and dirk pietruschka in “optimisa- tion and economics of solar cooling systems” have calculated the cost of each ac solar cell for cooling power / kw which are presented in <fig. > below. copyright©world technopolis association table . results of calculation of water production cost savings with eco-in- novation expected saving value unit the production cost of water (normal price) , rp/m the composition of the electricity cost % the composition of the chemical cost % electricity ( %) , rp/m chemicals ( %) rp/m with water feedstock from rain water - - electricity ( %) . rp/m chemicals ( %) . rp/m production cost rp/m production cost saving rp/m production cost saving daily , , rp. production cost saving annually , , , rp. sri setiawati, hadi alikodra, bambang pramudya, and arya hadi dharmawan, wtr ( ): article copyright©world technopolis association table . calculation of savings with libr solar powered ac an operational cost per year for solar cell ac includes power delivery, electricity, and equipment maintenance and water circulation. calculations using regression analysis to ob- tain the graph ac power relations and operational costs per year in euros can be calculated in each scenario. comparison of the data in the conventional ac and libr so- lar powered ac in puspiptek with value investing and the cost savings calculation results are presented in <table > below. for the implementation of eco innovation with libr solar powered ac will save rp. , , , per year. . eco innovation using led lights besides saving air conditioning, it can be done by replacing the bulbs with led bulbs with the same strong irradiation. this calculation is performed for pju lamp in puspiptek re- gion. for comparative analysis of cost savings results are pre- sented in <table >. the implementation of eco-innovation in the use of led lights at public street lighting in the puspiptek area saved rp. , , per year. . analysis submodel eco-innovations domestic waste management puspiptek is cover areas for laboratories, offices, housing and technology-based industrial zone (development plan). the types of waste include domestic wastewater, domestic waste, laboratories waste and hazardous and toxic (b ) waste. b waste generated that has been handled well in puspiptek includes b waste from laboratories and radioactive waste from nuclear research installations. the implementation of eco-innovation model that was car- ried out in the domestic waste management, was calculated on the basis of the organic waste from fallen leaves and do- mestic waste. this new concept is considered as a new break- through model which improve the behaviour of the people living in puspiptek. composting financial analysis has been carried out in or- fig. . costs required for every cooling power source: eicker and pietruschka sp ec ifi c co st w ith ou t v at / eu r kw - cooling power / kw iea handbook table . comparison of cost savings between led lightsand conventional light at public street lighting in the puspiptek area no parameter led lights conventional lights (bulb) life time , , electricity consumption (watt) price of lamp (rp.) , , use of electricity over , hours (watt) , electricity price (rp) , , , replacement lamp for , hours (times) cost for replacement lamp (rp.) , , total cost over , hours (rp.) , , , cost savings for , hours (rp.) - , , the savings for all public street lighting in the puspiptek area / , hours (rp.) , , , - saving annually (rp.) , , - investment in led lights , , - parameter existing / conventional ac libr solar powered ac investment costs (rp.) , , , , , , installation cost (rp.) , , , , integration cost(rp.) , , , , total capital cost(rp.) , , , , , , annual expenses(rp.) , , , , , difference in annual expenses/cost savings (rp.) , , , wtr ; : - http://dx.doi.org/ . /wtr . . . der to calculate the net income for composting. financial analysis in eco-innovations compost processing is presented in <table > below. revenue from composting and waste plastic sale obtained rp. , , per year. this study is in line with study that have been done in simongan industrial park in semarang city. the study concluded that eco-effi- ciency on recycle water waste in industry galvanis has made efficiency . % in and . % in . meanwhile, far- macytical industry developed eco-efficiency through reuse of paper, waste management of paper and cbrne. it has been an impact to decrease cost operasional of company (zaenuri ). some of the assumptions used in the analysis of the feasibil- ity of the implementation of the eco innovation are: ) investment cost required only in year ) maintenance cost required in year to ) ponds (“embung”) maintenance fee is % of investment value per year ) increase in electricity tariff is % per year ) increase in costs & income is % per year in the feasibility analysis, the savings obtained with the im- plementation of eco-innovation is considered as income. fixed capital investment is calculated from the cost of equip- ment and other expenses incurred by the implementation of innovations in water, waste and energy management that has been previously calculated. the feasibility analysis was performed by calculating several parameters, namely: net present value (npv), internal rate of return (irr) and payback period (pbp). npv is the present value of an investment’s expected cash inflows minus the costs of acquiring the investment. irr is the interest rate at which the net present value of all the cash flows (both positive and negative) from a project or investment equals zero. irr is used to evaluate the attractiveness of a project or investment. pbp is the amount of time taken to break even on an invest- ment. this feasibility analysis generates npv at a % discount fac- tor of rp. , , , ; irr . % and pbp . year. based on those indicators, it can be concluded the model of eco-in- novation in the area puspiptek is feasible to implement. tian et al. ( ) have conducted study of the performance of eco-industrial park development in china. the finding shows that ( ) industrial added value of eco-industrial parks as whole increased by %; ( ) for energy consumption, fresh water consumption, industrial waste water generation and solid waste production of eco-industrial park as whole in- creased %, %, %, and % respectively. furthermore, eco-efficiency programs in puspiptek have been designed in line with president instruction no. , on energy and water saving. the instruction is guidance of government of- fice to make action plan relating to energy and water savings on their office management. copyright©world technopolis association table . financial analysis results of compost processing parameter value unit capacity m /day volume of plastic waste kg/day fine compost selling price rp/kg granulescompost selling price , rp/kg plastic selling price , rp/kg daily labor cost , rp/hari daily labor number peoples electricity tariffs rp/kwh hours of operation hours power requirement % of load kw number of working days days cost of maintenance / labor % * labor cost of packaging % * value of sales assuming all the products sold in the form of fine compost volume of fine compost production , kg/day operating costs , , rp/year electricity costs , , rp/year labor costs , , rp/year maintenance costs , , rp/year packaging cost , , rp/year revenue , , rp/year fine compost , , rp/year plastic , , rp/year margin / profit results , , rp/year sri setiawati, hadi alikodra, bambang pramudya, and arya hadi dharmawan, wtr ( ): article . conclusions and recommendations . conclusion based on this research, a model of policy for development of eco-innovation park(case study of center for research of science and technology “puspiptek” south tangerang city) is concluded as follows: ) eco-innovation on water management with scenarios wa- ter feedstock by % of the total requirement comes from the ponds in the area. the savings that can be achieved with the implementation of eco-innovation in the water management is rp. , , daily, or rp. , , , per year ) the savings derived from the implementation of eco in- novation through replacement of central ac to ac libr solar powered will be rp. , , , annually, and the use of led lights in the public street lighting puspiptek saved rp. , , per year ) eco-innovation in waste management will be able to raise awareness of the environment by sorting organic, inor- ganic and plastic waste. composting and plastic waste obtained from the sale revenue is rp. , , per year ) overall, implementation of the eco-innovation system in puspiptek area can saves rp. , , , per year, compared to the existing system. ) the savings that are obtained with implementation of eco-innovation is considered as income. analysis of the feasibility of the implementation of eco-innovation in wa- ter, energy, and waste management in puspiptek gives npv at a % discount factor in rp. , , , ; . % of irr and . years of pbp. thus the model of eco-inno- vation in the area puspiptek is feasible to implement. . suggestion some research suggestions in the preparation for develop- ment of eco-innovation in puspiptek area are as follows : ) to get the title as the eco-innovation park, it is recom- mended that puspiptek management make the strate- gic planning involving consultant certified by green building council indonesia (gbci). ) policy to make puspiptek as regional eco-innovation di- rected towards the development of infrastructure facili- ties of water, energy and waste management will have an impact on cost savings and increase environmental qual- ity and comfort for the occupants of the region. references akbar i. ( ) design of cooling system solar thermal power kw, thesis (master degree), gadjah mada university, yogyakarta, indonesia, [in indonesian]. andersen, m. m. ( ) eco-innovation indicator, european environment agency, copenhagen, denmark. arsyad, s. ( ) water and soil conservation, ipb press publisher, bogor, indonesia, pp. - . eicker, u., and pietruschka, d. ( ) “optimisation and eco- nomics of solar cooling systems, university of applied sciences stuttgart,” advances in building energy re- search ( ): - . green building council of indonesia. ( ) “guidance of implementation of greenship,” accessed july , , www.gbciindonesia.org, [in indonesian]. oecd ( ) eco-innovation: framework, practices and measurement (synthesis report), sustainable manufac- turing, oecd, paris, pp. . republic of indonesia. ( ) law no. , on basic rules of agrarian, state gazette no. / , jakarta, indonesia, [in indonesian]. sarkar, a. n. ( ) “promoting eco-innovations to leverage sustainable development of eco-industry and green growth,” european journal of sustainable develop- ment ( ) : - . sakr, d., baas, l., el-haggar, s., and huisingh, d. ( ) “crit- ical success and limiting factors for eco-industrial parks:- global trends and egyptian context,” journal clean production ( ): - . tian, j., liu, w., lai, b., li, x., and chen, l. ( ) “study of the performance of eco-industrial park development in china,” journal of cleaner production xxx ( ): - . zaenuri, m. ( ) environmental management of industry model through eco-efficiency samongan industrial park in semarang city, report of research insentif of doctoral program , dipenogoro university, sema- rang, indonesia, [in indonesian]. copyright©world technopolis association wtr ; : - http://dx.doi.org/ . /wtr . . . utilization of solar energy for photoreduction of industrial wastewater containing hexavalent chromium with zinc oxide semiconductor catalyst utilization of solar energy for photoreduction of industrial wastewater containing hexavalent chromium with zinc oxide semiconductor catalyst pallavi mitra*, prantik banerjee, sampa chakrabarti, sekhar bhattacharjee department of chemical engineering, university of calcutta, , acharya p.c. road, kolkata , india tel. + ; fax: + ; email: pallavim @gmail.com received june ; accepted december a b s t r a c t scarcities of water and energy are going to be critical in the near future. a possible remedy is to reuse industrial wastewater after suitable treatment using a renewable energy. in this work, wastewater containing hexavalent chromium is treated with zinc oxide (zno) semi- conductor photocatalyst in the presence of sunlight to reduce the more toxic hexavalent metal to its less toxic trivalent counterpart. thirty five percent reduction was obtained after h with mg/l substrate, . g/l photocatalyst, and klux solar radiation at oc tem- perature. process parameters are initial concentration of substrate, loading of photocatalyst, ph and concentration of the electron donor. initial rate of reduction varied only with zno- loading and hence it was zero order with respect to both the substrate and electron donor. an alternative rate equation based on the modified langmuir hinshelwood hougen watson (lhhw) model compares well with the mechanistic rate equation. keywords: hexavalent chromium; solar energy; photoreduction; zno-semiconductor . introduction among the total world population of , million, approximately million people are suffering from chronic water scarcity and nearly one billion people do not get safe drinking water [ ]. the most rational and reasonable remedies for this water crisis are to minimize wastage of water as well as to recycle and to reuse industrial wastewater. treatment of industrial wastewater will demand a huge amount of energy in the coming years. energy crisis, in turn, will worsen the problem of water crisis and vice versa since water and energy are very closely related. energy required to produce such a large quantity of treated water will not be easily available from the conventional sources. so a serious participation of a non-conventional and renewable source of energy for the treatment of water and wastewater is required [ ]. solar energy is the most competent candidate as a source of renewable energy [ – ]. india is a tropical country and the daily average solar energy incident over india varies from to kwh/m with about , – , sunshine hours per year, depending upon location [ , ]. hexavalent chromium is used in a variety of industries including leather-chrome tanning, preserva- tion of wood, production of stainless steel and textile dyes. hence, hexavalent chromium comes into waste- water from such industries. chromium is a priority*corresponding author. - / - � balaban desalination publications. all rights reserved. desalination and water treatment www.deswater.com doi: . / . . ( ) – august journal of modern power systems and clean energy, vol. , no. , march infrastructure of sustainable energy development in pakistan: a review sidra kanwal, bilal khan, and muhammad qasim rauf abstract——pakistan is an energy-resourceful country with vast and untapped renewable energy sources (ress). the wind, so‐ lar, and biomass of the country are practically capable of end‐ ing a power sector collapse caused by demand-supply variances. a significant percentage of pakistan’s population resides in ru‐ ral areas. for rural population, the lack of connection to the mainstream of national development is a direct consequence of frequent power blackouts and, in certain cases, a lack of grid connection altogether. lucrative features of smart grid are not fully incorporated into the power network yet, but policy-mak‐ ers are paying attention to increase res reliance. a comprehen‐ sive study describing the renewable energy potential of paki‐ stan is of importance. this research work attempts to present a collective summary of pakistan’s renewable energy potential. a statistical analysis of the proposed and installed projects in vari‐ ous districts are presented. this paper elaborates the pressing needs of renewable energy integration for resolving pakistan’s energy crisis. renewable energy projects are acclaimed in this paper for affording higher living standards and better job op‐ portunities than the fossil fuel based industry in pakistan. inte‐ grating ress into the national portfolio is guaranteed to offer profound socio-economic benefits to pakistan’s rural population. index terms——biomass energy, geothermal energy, renewable energy source (res), solar energy, smart grid, wind energy. i. introduction pakistan’s energy crisis is attributed to an ever-increasing population size, followed by consumers being subjected to frequent load shedding. a stable energy supply is crucial for the development of the social and economic fabric of the so‐ ciety. the task is feasible in terms of home-grown conven‐ tional energy reserves. pakistan primarily relies on foreign imported fossil fuels to fulfill its energy demand, and ex‐ pends approximately % in crude oil imports [ ]. pakistan has about . % of the total worldwide popula‐ tion, and is the world’s sixth most populous country [ ]. the geographical location of pakistan benefits international maritime trade immensely and presents a lucrative paradigm for foreign investment. stable energy supplies to handle cur‐ rent and future energy demand will depend on power genera‐ tion from sustainable energy sources. imported crude for electricity generation is an established fiscal burden on the economy [ ] —a situation further aggravated by depleting home-grown natural gas reserves. the country’s installed power generation capacity is rated at mw, with a peak demand of mw. figure illustrates that the power demand is growing by % to % annually, in con‐ trast with an annual supply growth of only % [ ]. urban areas are frequently subjected to a regular to hours of load shedding, while the average load shedding in rural areas is hours. the contribution of renewable ener‐ gy sources (ress) in power generation was reported to be less than % in . however, the government seeks to ramp up res contribution by % until the year [ ]. residential and commercial sectors are major electricity con‐ sumers due to the significant number of indoor electricity ap‐ pliances. the increase in the number of appliances is a di‐ rect consequence of the rapid technological development and urbanization of the rural community. the attention gathered by the vast and untapped renewable energy reserves in paki‐ stan is expected to effectively meet the country’s energy re‐ quirements [ ]. a summary of pakistan’s current energy resources is de‐ picted in fig. [ ]. the current energy shortfall indicates that the existing energy infrastructure is insufficient for coun‐ tering the increasing energy demand. thus, the ultimate solu‐ tion of the problem is to increase the renewable energy pene‐ tration in pakistan’s energy spectrum. pakistan has a huge potential for res, despite little attention has been paid to its benefits. chief sources for electricity generation in pakistan are natural gas, oil, and coal. hydro energy contributes % toward the total energy mix. po w er 	 g w ) year supply demand fig. . power demand-supply trends of pakistan. manuscript received: april , ; accepted: december , . date of crosscheck: december , . date of online publication: march , . the authors are grateful to anonymous reviewers for providing valuable sug‐ gestions and comments to improve the work. this article is distributed under the terms of the creative commons attribu‐ tion . international license (http://creativecommons.org/licenses/by/ . /). s. kanwal (corresponding author) and b. khan are with the department of electrical and computer engineering, comsats university islamabad, abbot‐ tabad campus , pakistan (e-mail: sidrakanwal@ciit.net.pk; bilalkhan@ciit. net.pk). m. q. rauf is with the department of electrical engineering, capital university of science and technology, islamabad, pakistan (e-mail: muhammadqasimrauf@ gmail.com) doi: . /mpce. . kanwal et al.: infrastructure of sustainable energy development in pakistan: a review countries adopting ress for power generation experience both positive and negative impacts. even though res adop‐ tion provides self-sufficiency of the energy, the country’s heavy reliance on fossil fuels shows that ress are not suffi‐ cient to phase out fossil fuels entirely. reference [ ] investi‐ gated the factors of economic growth, energy consumption, fiscal development, and relative prices for high-income orga‐ nization for economic cooperation and development (oecd) and non-oecd countries. reference [ ] investigated the link between economic development and energy consump‐ tion, and indicated that economic growth increases together with renewable energy consumption. reference [ ] ad‐ dressed the issues related to the electricity sector, analyzed the current regime’s policies, and discussed their impact on the electricity sector. also, it is found that the cost of fuel and the emission of hazardous gases are increasing due to the imports of fossil fuels. reference [ ] provided statistical information about ress in pakistan. it is found that ress have a huge poten‐ tial, the utilization of which will overcome the energy crisis. reference [ ] inspected pakistan’s energy sector in detail by addressing the infrastructure that generates and distributes the energy. it asserted that the consumption of ress plays a significant role in economic growth and argued that renew‐ able energy generation should be increased. it also explained that ress are the best alternative to overcome the energy cri‐ sis, though barriers that punctuate progress are also ad‐ dressed. reference [ ] investigated the relationship between inflation and the energy crisis. it explained the situation of energy sector, both globally and in pakistan, and inspected key factors contributing toward energy inflation. it collected annual data related to energy inflation such as the exchange rate, international oil prices, energy imports, the tax ratio, and the money supply from to . reference [ ] ex‐ amined various factors contributing to the energy crisis that contains reduced reserves of oil and gas, an energy gap be‐ tween supply and demand, security concerns over the power supply, and energy costs. a solution to the entire problem is renewable energy generation. reference [ ] investigated the potential capacity of energy production through renewable energy technologies (rets) within pakistan. current energy crisis requires balancing energy supply-demand curve with ress as reliable solution [ ]. reference [ ] explained that rets must be utilized to fulfill energy demand and supply gap. it examined the demand and supply gap in pakistan and inspected various geographical locations for ret installa‐ tion. according to [ ], solar, wind, and biomass energy po‐ tential exists abundantly in pakistan, which can meet the en‐ ergy needs. it is explained that the solar energy returns its in‐ vestment cost within years; the biomass energy and wind energy return their investment cost within years, while par‐ abolic trough collectors (ptc) produce returns within years. reference [ ] inspected problems related to biomass energy utilization effectively and efficiently. it also deduced that local government must be considered as the main factor while establishing a biomass-based electricity plant. refer‐ ence [ ] deduced that biomass can supply percent of the power portfolio in pakistan. reference [ ] studied the de‐ velopment for bioenergy using anaerobic digestion, and found that separate biogas plants can be installed in an area that has no electricity. reference [ ] discussed prospects of both wind and solar energy in pakistan. reference [ ] stud‐ ied the current status of solar energy generation in pakistan and emphasized that the main hindrance is the high capital cost to install solar technologies. reference [ ] surveyed the quetta district of pakistan and determined rich potentials of solar energy in the area. an ret screen simulation showed that about . gwh of electricity can be pro‐ duced in a year. a photovoltaic (pv) plant will generate elec‐ tricity at a rate of . $/kwh, at a total cost of $ mil‐ lion, and a percent debt ratio. reference [ ] provided a detailed analysis of wind energy development in pakistan, and provided guidelines for increased wind energy. a sum‐ mary of some generic state-of-the-art surveys is illustrated in table i. all studies emphasized the need to develop alternative en‐ ergy sources and challenges related to the implementation of alternative energy sources at the national level. some re‐ search has been conducted at the regional level. reference [ ] examined the wind energy potential in pakistan and the challenges related to the installation of such facilities. it also inspected the reserve of mwh energy, while half of the residential consumers in karachi have installed micro wind turbines. reference [ ] conducted the research on urbaniza‐ tion, growth of vehicle use, energy consumption, co emis‐ sion, and industrialization, and deduced that the urban area and its population increased by percent from to . an investigation also revealed that the consumption of natural gas, coal, and gasoline increased by %, %, and %, respectively. the main contributions of this paper are as follows: ) a discussion of the energy crisis in pakistan and its worsening impact on the social and economic fabric of the country is presented. energy demand is far greater than the existing infrastructure of supply, and res-based power gen‐ eration is the ultimate solution to the problem. ) a quantitative analysis of current and future res pow‐ er generation in pakistan is presented at considerable length. ) a comprehensive depiction of the dire need and status of implementing a smart grid (sg) in pakistan is illustrated. % % % % % gas; coal; oil; hydro; nuclear fig. . share of conventional sources for power generation in pakistan. journal of modern power systems and clean energy, vol. , no. , march the remainder of this paper is organized as follows. sec‐ tion ii presents an overview of ress in pakistan along with strengths, weaknesses, opportunities, and threats (swot) analysis of its energy system. the status of sg implementa‐ tion and suggestions for ret development are discussed in section iii. finally, section iv concludes the paper and pro‐ vides future approaches. ii. status of res utilization in pakistan according to an estimate, pakistan is blessed with solar ra‐ diations of . wh/m per day. wind speed is - m/s in the shoreline front territories of sindh and baluchistan. the po‐ tential of energy generation from wind is more than gw [ ]. figure clearly demonstrates that ress are able to table i summary of some generic state-of-the-art surveys ref. [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] our survey technology renewable energy generation wind energy biomass/biogas energy hydro solar energy ba × × × × × × × 􀳫 × × × × × × × × × 􀳫 × × × × × × × × × × × × × × × × × × × × × × 􀳫 fp 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 rdc × × × × 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 × × × 􀳫 × × 􀳫 × × 􀳫 × 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 tp 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × × 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 gp 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 mp 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 × × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 ts × × × × × × 􀳫 × × × × × × × × 􀳫 􀳫 􀳫 􀳫 × × × × × × 􀳫 × 􀳫 􀳫 × × 􀳫 􀳫 􀳫 × 􀳫 􀳫 × 􀳫 × × sa × 􀳫 × × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 ei × × × × 􀳫 􀳫 􀳫 × 􀳫 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 × × × 􀳫 × 􀳫 􀳫 􀳫 × × 􀳫 × × × × × × × 􀳫 × × 􀳫 ca × 􀳫 􀳫 × × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × × 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 × × 􀳫 × 􀳫 × 􀳫 􀳫 sep × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 × × 􀳫 × 􀳫 × × 􀳫 × 􀳫 × 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 × × 􀳫 gpa × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 × 􀳫 􀳫 × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 gt 􀳫 × × × × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 × × × × 􀳫 × × × 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 􀳫 × 􀳫 􀳫 × × 􀳫 note:􀳫: explored; ×: not explored; ba: bibliometric analysis; fp: future prospects; rdc: real-time data collection; tp: theoretical potential; gp: geographi‐ cal potential; mp: market potential; ts: technical study; sa: statistical analysis; ei: ecological impact; ca: cost analysis; sep: socio-economic potential; gpa: geo-political assessment; gt: global trends. kanwal et al.: infrastructure of sustainable energy development in pakistan: a review complement pakistan’s energy requirements for providing a sustainable energy base [ ]. the main reasons for the energy crisis in pakistan are an imbalance in the energy mix, the non-utilization of numer‐ ous indigenous energy resources, a deficiency of investment in power, political instability, energy policy failure, and high energy production costs. other crisis factors are political ar‐ guments over mega-energy projects, corruption by both pro‐ ducers and consumers, and an old transmission and distribu‐ tion infrastructure [ ]. the significant energy utilization sec‐ tors in pakistan are domestic, commercial, industrial, agricul‐ tural, government, and transportation. the increase in energy consumption in these sectors are %, . %, . %, . %, . %, and . %, respectively. the present energy deficit is around mw and the annual increase in demand is %, while the supply rate is % [ ]. table ii demonstrates predictive information about peak demands, available genera‐ tion, and energy gap of electricity from to [ ]. pakistan’s energy demand is predicted to increase at a rate of % until . the government must attempt to orga‐ nize, facilitate, and encourage all power generation technolo‐ gies [ ]. a. conventional energy sources numerous countries of the world are completely depen‐ dent on conventional energy sources, triggering a fast deple‐ tion of these sources. the utilization of these sources pol‐ lutes the environment due to the emission of harmful gas and waste production. figure illustrates conventional and non-conventional energy sources [ ]. the chief convention‐ al energy sources of pakistan are briefly described in this section. ) coal resources pakistan has sixth largest coal reserves with total coal re‐ serves of nearly billion tons. the largest reserve of low- quality coal of about billion tons is found in thar, which has the capability to generate power of mw. thar coal reserve has heating value of to btu/lb, jherruck and lakhra have and million tons of coal, respectively. the main consumers of coal resources are the cement sector and the brick kiln industry. the share of the cement sector in the consumption of coal resources is %, and the share of the brick kiln industry is about % in [ ]. ) oil resources the oil resources of pakistan are about million barrels. daily oil production is about barrels. thirteen compa‐ nies are working to produce crude oil from oil fields. the transportation and power sectors are the main consum‐ ers of petroleum products. the consumption of petroleum products by the transportation sector in - is . %; by the power sector, . %; and by the industrial sector, . % [ ], [ ]. ) natural gas resources the total natural gas reserves of pakistan are about trillion cubic feet (tcf). daily natural gas production is about billion cubic feet. fifteen companies are working to produce gas from gas fields, of which are associated (a natural gas reservoir with petroleum deposits) and are non-associated (a natural gas reservoir without crude oil de‐ posits). the largest reserve of natural gas is found in sui, with potential of about . tcf. the power sector is the largest consumer of gas in - , consuming . %; the industrial share is . %, and the household share is about . % [ ], [ ]. ) nuclear energy resources the development and operation of nuclear power plants are the responsibility of the pakistan atomic energy com‐ energy resources conventional non-conventional solar hydro wind geothermal ocean biomass/biogas waste heat fossil fuel coal oil natural gas nuclear wave tidal fig. . taxonomy tree of conventional and non-conventional energy sources. table ii power demand and supply from to year month jan. jul. jan. jul. jan. jul. jan. jul. jan. jul. peak demand (mw) available generation (mw) energy gap (mw) - - - - + + + + + + co-generation/biomass/waste to energy solar; wind; small hydro; geothermal . % . % . % . % . % fig. . pakistan’s res potential. journal of modern power systems and clean energy, vol. , no. , march mission (paec). table iii depicts the information on the country’s nuclear plants [ ]. chashma nuclear power plant units and (c- and c- ) and the karachi nuclear power plant (kanupp) are working with a capacity of mw. the government directed paec to increase its capacity of electricity production to mw by . paec has de‐ cided to build a huge civilian enrichment plant to expand the program. these plants, when successfully installed, will pro‐ vide the employment and will resolve the energy demand is‐ sue to a great extent [ ]. b. ress the accessible potential and status of ress in pakistan are discussed in the following subsections. ) solar energy solar energy has a huge share in fulfilling worldwide ener‐ gy demand with the least unfavorable environmental conse‐ quences. according to a solar map prepared by the national aeronautics and space administration (nasa), pakistan is the second highest area to receive solar irradiation [ ]. the annual solar irradiance received by pakistan is around - kwh/m [ ]. these enormous solar radiations make so‐ lar a highly recommended energy generation source. solar re‐ source potential in pakistan is demonstrated in table iv [ ]. the descriptions for kesc, hesco, sepco, mep‐ co, fesco, lesco, gepco, iesco, fata, kp , kp , ajk can be found in [ ]. the total estimated energy that can be generated from so‐ lar is . tw. bahawalpur has the maximum number of annual sunshine hours, an average of hours per year. the regions of gilgit and chitral receive the least amount of solar radiation, hours per year. the first solar genera‐ tion plant went into operation in september in baha‐ walpur with a potential to produce mw of energy. the second phase of this project, with a generation capacity of mw, went into operation in . details of projects un‐ der implementation, completed, or with a letter of intent (loi) issued, are listed in table v [ ]. table iii operational nuclear power plants ( ) plant kanupp c- c- contractor candu owners group (cog), canada china national nuclear corporation (cnnc), china cnnc, china capacity (mw) construction started aug. aug. dec. commercial operation dec. sept. may table iv solar resource potential in pakistan ( ) sub region kesc baluch baluch baluch baluch hesco sepco mepco fesco lesco gepco iesco fata kp kp ajk gilgit total maximum average instant solar insolation . . . . . . . . . . . . . . . . . . solar resource capacity (tw) . . . . . . . . . . . . . . . . . . table v list of solar power projects ( ) project quaid-e-azam solar park conergy solar project bakhsh energy solar first solar wah industries limited solar scatec solar project solar energy pakistan limited dacc llc solar cwe solar pakistan parliament tech access solar ssjd bagasse energy roshan power solar status mw operational; mw will be operational in under implementation loi issued loi issued loi issued set up starts loi issued loi issued loi issued under implementation loi issued under implementation loi issued location bahawalpur bahawalpur lodhran punjab taxila sindh thatta sindh cholistan islamabad punjab jhimpur kasur capacity (mw) kanwal et al.: infrastructure of sustainable energy development in pakistan: a review pakistan is an agrarian country. most people living in ru‐ ral areas are deprived of electricity, and the maximum ener‐ gy demand of every house is - w. the extension of transmission lines is impracticable and uneconomical for such a small load. solar energy can help electrify these areas [ ]. thus, the project was initiated, and about solar home systems were installed in villages of thar parker, sindh. the second phase of this program has been approved, and it will provide solar home systems to and villag‐ es in sindh and baluchistan, respectively. ) hydro energy annual surface flow rate of water in pakistan is mil‐ lion acre feet (maf) [ ]. hydro power plants are suitable for pakistan because of its abundant water supply and low generation cost. most of the hydropower resources are in the northern areas of pakistan. table vi demonstrates the details of hydropower generation for operational projects, under-im‐ plementation projects, and projects with completed feasibili‐ ty analyses [ ]. northern areas of pakistan have numerous sites, where energy generation is possible in the form of mini and micro hydel power plants. the hydro power genera‐ tion potential for micro hydel plants is about mw [ ]. ) geothermal energy pakistan lies on the intersection of seismic-tectonic plates. thus, the country has plentiful geothermal resources. the geo-pressurized system, the seismic-tectonic system, and the neogene-quaternary system are three environments where geothermal resources can be found. it is estimated that paki‐ stan can produce gw of electrical energy from geother‐ mal sources [ ]. numerous geysers, hot springs, and mud volcanoes are available, with temperatures ranging from ℃ to ℃ . no locality has yet been introduced for the direct or indirect use of geothermal energy [ ]. no attempt has been made to utilize geothermal energy in the himalayan range of paki‐ stan [ ]. currently, there is no power plant for geothermal energy, but there are many locations where the electricity generation is possible. details of the geothermal resources in various locations of pakistan, along with the temperature cat‐ egory, the surface temperature, and weather geothermal ener‐ gy are categorized in table vii [ ]. geothermal power plants can provide power grid support, as it produces constant output power because of its day-and- night availability. both the private and public sectors of paki‐ stan should contribute to the practical implementation of geo‐ thermal power plants to overcome the energy crisis [ ]. ) wind energy wind is another significant source of ress. the radiation and rotation of the earth affect the direction and speed of the air. the heat difference between the land and sea also affects wind flow. consequently, the region that lies near water and coastal areas has more wind energy potential [ ]. wind power is classified into different classes. class is poor, class is marginal, class is moderate, class is good, and the remaining classes are excellent. according to the nation‐ al renewable energy laboratory (nrel), classes and above are appropriate for the installation of wind turbines to generate energy. class is suitable for rustic claims [ ]. pakistan is installing wind energy plants in gharo, bin qa‐ sim, keti bandar, and jhimpir. the first wind energy plant was installed in . sindh and baluchistan have the poten‐ tial more than mw, whereas the wind energy poten‐ tial of punjab is only mw [ ]. the pakistan meteorological department has done surveys throughout the country to determine the potential of wind en‐ ergy. after collecting data from sites, the potential of wind energy was estimated, and it was found that a km area at the coastal belt is suitable for wind energy pro‐ duction, and can produce mw of power [ ]. table viii shows that about % land of pakistan is suitable for wind turbines, giving the country a wind energy potential of mw [ ]. table ix illustrates that . % of total area of sindh lies in an adequate-to-outstanding wind power class. wind ener‐ gy potential is about mw. eighteen wind independent power projects (ipps) received land from the alternative en‐ ergy development board (aedb) to implement wind pro‐ duction plants, and each plant will have a capacity of mw. eight ipps have received licenses from the national electric power regulation authority (nepra), and four ipps received tariffs from nepra [ ]. the total land area of khyber pakhtunkhwa (kpk) is over km . table x shows that a km area, or more than % of the total area, lies in a moderate-to-excellent wind power class [ ]. table vi summary of hydro power resources in pakistan ( ) region kpk gilgit baltistan punjab azad jammu kashmir sindh baluchistan total power of operational projects (mw) power of under implementation projects (mw) public sector private sector provincial federal power of solicited sites (mw) power of projects with raw sites (mw) total (mw) journal of modern power systems and clean energy, vol. , no. , march the area of baluchistan is over km . table xi shows that km ( . % of the area) are in a moderate- to-excellent class. the potential of wind energy production of baluchistan is nearly mw. it is obvious from ta‐ ble xi that the potential area of classes and is larger than other provinces [ ]. table xii indicates that the sindh province of pakistan is suitable for the installation of wind energy projects [ ]. six projects are in operation, and the total power generation is . mw. nine projects are under construction and the to‐ tal power generation is mw. thus, mw will be added to the national power system upon successful comple‐ tion of these projects. ) biomass/biogas energy pakistan has self-sufficient biomass resources. punjab province is capable of producing . twh electricity an‐ nually from extra and accessible crop biomass of about . million tons [ ]. the number of animals in pakistan is over million, plus about million birds in poultry farms. plant residues are about million tons per year. ani‐ mals produce million kg of % collectable dung per day. birds produce . million kg of % collectable dung per day. in all, . million cubic meters of biogas are achieved daily, which generates the power of mw from crop residues. moreover, mw of energy is pro‐ duced from . million cubic meters of biogas daily in punjab. biogas plants produce biogas as well as organic fer‐ tilizer in slurry form. table viii pakistan wind resources assessment class total potential outstanding outstanding outstanding good adequate capacity (mw) wind land area (km ) percent of wind land area (%) . . . . . . table ix sindh wind resource assessment ( ) class total potential outstanding outstanding outstanding good adequate capacity (mw) wind land area (km ) percent of wind land area (%) . . . . table x wind resource assessment of kpk ( ) class total potential outstanding outstanding outstanding good adequate capacity (mw) wind land area (km ) percent of wind land area (%) . . . . . . table vii survey of geothermal energy sources of pakistan ( ) location hunza hakuchar chagai volcanic arc karakoram granodiorite mashkin murtazabad tatta pani darkut pass budelas gilgit region koh-e-sultan chicken dik dadu district mango pir garam chashma salt range mianwali tc low low low moderate moderate moderate low low moderate low moderate low low low moderate low st (°c) - - - - - - - - . - - gr hot spring hot spring mud volcano hot spring hot spring hot spring hot spring hot spring hot spring hot spring mud volcano hot spring hot spring hot spring hot spring hot spring ppt rcp rcp rcp bcp bcp bcp rcp rcp bcp rcp bcp × rcp bcp bcp × ip np np np p p p np np p np p np np np p np dp p p p p p p p p p p p p p p p p ppg p p p p × p p p p p × × × p × × cpg × × × × × × × × × × × × × × × × note: ×: not explored; p: possible; np: not possible; rcp: ranking cycle plant; bcp: binary cycle plant; tc: temperature category; st: surface temperature; gr: geothermal resource; ppt: power plant type; ip: indirect applications; dp: direct applications; ppg: proposed power generation; cpg: current power generation. kanwal et al.: infrastructure of sustainable energy development in pakistan: a review table xiii illustrates that the potentials of biogas in paki‐ stan and punjab are about . million cubic meters per day and . million cubic meters per day, respectively [ ]. different sectors utilize natural gas to fulfill their energy needs. biogas can be an alternative to natural gas at negligi‐ ble cost. the government is beginning to install bio‐ gas plants throughout the country to fulfill the power de‐ mand of the country [ ]. due to financial restraints, only biogas plants have been installed so far. the remaining plants are still in the process of installation. initially, cooking was the only purpose of biogas plants. however, the commercial use of biogas has been advertised to farmers for the operation of tube wells. biogas plants have been installed and are in operation at different sites of table xi baluchistan wind resource assessment ( ) class total potential outstanding outstanding outstanding good adequate capacity (mw) wind land area (km ) percent of wind land area (%) . . . . . . table xii wind projects in sindh province of pakistan ( ) status of project operational in pipeline under construction project three gorges i wind farm sapphire wind power company ffc energy foundation wind energy i zorlu enerji foundation wind energy ii three gorges ii wind farm burj wind energy tricon boston consulting organization western energy tricon boston consulting organization shaheen foundation paf hawa energy trans-atlantic energy three gorges iii wind farm jhampir wind power zephyr power tricon boston consulting organization china sunec energy hartford alternative energy tenega generasi hydro china dawood power yunus energy gul ahmed wind tapal wind united energy metro power company master wind sachal energy development location jhimpir jhimpir jhimpir gharo jhimpir gharo jhimpir gajju jhimpir jhimpir jhimpir jhimpir jhimpir jhimpir jhimpir jhimpir jhimpir gharo jhimpir nooriabad jhimpir gharo gharo jhimpir jhimpir jhimpir jhimpir jhimpir jhimpir jhimpir capacity (mw) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . table xiii potential of biogas in punjab and pakistan ( ) location punjab pakistan accessible animal . × . × dung (kg/d) . × . × biogas from dung ( . m per kg dung) (m ) . × . × poultry bird . × . × poultry drop‐ ping (kg/d) . × . × biogas from poultry ( . m per kg poultry) (m ) . × . × annually crop scum (tons) . × . × biogas from crop scum (m /d) . × . × journal of modern power systems and clean energy, vol. , no. , march sialkot, jhang, and narowal in punjab [ ]. pakistan has the potential to generate mw of power from agriculture and municipal solid waste (msw) [ ]. energy generation from msw is comparatively low but is capable of reducing the energy crisis. according to a survey, about . tons of combustible msw are generated per day in peshawar. the energy produced from . tons of msw is . mw [ ]. in pakistan, the average calorific value of msw is . mj/kg. the total energy generation in the capital cities of pakistan from msw are gwh per year. table xiv demonstrates the calorific values of msw and the related moisture contents, according to area classifications [ ]. ) tidal energy tides originate from the gravitational forces between the earth and the astronomical bodies of our solar system. the current energy demand of the world will be successfully met if less than . % of the energy in the oceans is converted in‐ to electricity. delta creek areas of pakistan have the capacity to produce approximately mw energy from tidal cur‐ rents. according to surveys by the national institute of oceanology (nio), creeks that spread from korangi creek to kajhar creek near the pakistan-india border have a great capacity for tidal energy. the value of the current velocity recorded at these creeks is from to knots, but can be as high as knots. the heights of tidal waves are from to meters. the kalmat khor and sonmiani hor creeks of balu‐ chistan are considered as good sources of tidal energy in pakistan [ ], [ ]. ) wave energy waves result from wind action on ocean surfaces, and wind is, in turn, caused by the heat of the sun [ ]. waves produced on the surface of the water have energy travelling across it. every wave has various characteristics such as wind speed, water depth, wind duration, wind sliding dis‐ tance, and fetch (the distance it blows over open water) [ ]. the fluctuation in energy production from wave resources causes a nonlinear energy supply to power system. grid inte‐ gration problems can be solved by a linear supply of energy, using an energy storage system (ess). numerous storage technologies have been inspected such as flywheels, super‐ conducting energy storage, and super capacitors. however, few findings technically and economically validate the ess requirement for the integration of wave plant grid [ ]. wave power stations are in operation in many countries like portugal, spain, and israel. the world’s largest wave power station is in portugal, with a generation capacity of . mw [ ]. pakistan is rich in sea-related wave energy due to the existence of a km long coastal area. however, paki‐ stan is not utilizing wave energy. proper planning, manage‐ ment, and motivation are required to exploit wave energy sources to overcome the energy deficit [ ]. ) waste heat energy the emission of air pollutant gases can be controlled by the implementation of waste heat power plants (whpps). whpps are green energy producers and minimize overall en‐ vironmental pollution [ ]. a thermoelectric generator (teg) is used to convert waste heat into electrical energy. the char‐ acteristics of teg such as it does not have moving parts, does not require input power, can transfer reflexive heat, is small in size, and is lightweight, make it feasible for com‐ mercial and industrial use [ ]. the three main technologies used in electricity generation from waste heat are the steam- based rankine cycle system, the organic rankine cycle sys‐ tem, and the kalina cycle system [ ]. clinker production in the cement industry emits % of produced heat into the at‐ mosphere, causing environmental pollution. thus, the instal‐ lation of a teg helps minimize air pollution and can also contribute some proportion to the electrical load [ ]. nu‐ merous industries in pakistan are potentially capable of in‐ stalling whpp to get the benefit of their waste heat. table xv displays the information on waste heat recovery plants in several industries. whpp can minimize the dependency of industry on the national grid as well. c. swot analysis of pakistan’s energy system an swot analysis is a common practice used by both in‐ dustry and academia for strategic planning purposes. it high‐ lights the strengths and weaknesses of a fundamental energy system. moreover, it explores the opportunities for invest‐ ment, and the probable threats of delay in achieving the tar‐ get. an swot analysis will help propose actions and mea‐ sures that can be recommended for the roadmap. the major outcomes of an swot analysis of pakistan’s energy system are depicted in fig. . iii. status of sg implementation in pakistan the social and economic development of any country is estimated from its energy utilization. pakistan is unable to tackle its increasing energy demands due to the limited num‐ ber of explored energy sources. consequently, most people in the country are deprived of the electricity. the existing power infrastructure depends heavily on hydro power genera‐ tion. table xiv calorific values of msw ( ) classification commercial area low income residential area medium income residential area high income residential area industrial area calorific value (mj/kg) . . . . . moisture content (%) table xv waste heat recovery power plants ref. [ ] [ ] [ ] [ ] [ ] [ ] industry bestway cement limited bestway cement limited bestway cement limited d.g.k. cement company d.g.k cement company fauji cement company region chakwal hattar farooqia d.g. khan khairpur attock output (mw) . . . . . . kanwal et al.: infrastructure of sustainable energy development in pakistan: a review moreover, fossil fuel based power generation is unreliable due to the power demand that is increasing day by day. paki‐ stan is thus trying to exploit indigenous energy sources of so‐ lar, wind, and biomass on a commercial scale. the sg needs to be introduced to overcome transmission and distribution challenges and losses [ ]. the sg is not in full operation in pakistan, but power gen‐ eration from ress is in practice. moreover, nepra issued smart meters and tariff guidelines in for the electricity demand of consumers. consumers can sell their surplus elec‐ tricity back to the grid by generating their own energy from solar or biomass resources. smart meters record electricity flow both in and out, and only the net amount is charged. the incentive of selling surplus electricity to the grid moti‐ vates people to generate their own electricity utilizing ress. electricity crises can be handled in this way. smart meters record various electrical parameters in different time slots ranging from minutes to hours. recorded data gives a proper understanding of load consumption and a more thorough pic‐ ture of particular event occurrences. lately, most of paki‐ stan’s traditional power system relies on manual energy me‐ ter reading. consequently, there is severe energy theft and much corruption in the recorded data. the flawed data leads to defective load consumption information, thus affecting on- demand management approaches. the government is motivating people to install smart me‐ ters due to the meters’ credibility. moreover, they can gener‐ ate alarms in various monitored situations like identifying grid energy losses. smart meters can store data, so it can be retrieved from the meter in case of poor communication. this feature is conspicuous for pakistan’s energy theft is‐ sues. the load control feature of smart meters allows the en‐ ergy generation side to meet peak demand. however, the available smart meters in pakistan lack the control of individ‐ ual loads, and the implementation of efficient demand re‐ sponse plans requires intervention by computers or human beings. bidirectional energy flow measurement meters are in‐ stalled mostly for industrial consumers. the government is planning to install prepaid energy meters. in this way, the timely identification and elimination of power theft and loss‐ es can be made possible by incorporating smart meters into the energy mix [ ]. the implementation of sg is challenging due to the unreli‐ able transmission network in pakistan. sg can only be inte‐ grated in the main grid under the compatible and synchro‐ nized phase conditions and the constant voltage from distrib‐ uted energy sources. the reliability of any transmission sys‐ tem is estimated by its duration and the number of outages. pakistan’s power grid has encountered many unplanned and forced outages. thus, attention is directed toward the integra‐ tion of rets in the energy mix. the aforementioned detailed description of ress shows that distribution generation is the last resort to overcome declining energy economy of paki‐ stan [ ]. the following suggestions are made for ret development and the effective utilization of rets in pakistan. ) ending the fossil fuel dependence of the economy and embracing renewable alternatives are daunting tasks. it is crucial to devise laws and policies to encourage investment in rets. ret investment should be facilitated by energy policies that encourage tax rebates and financial leasing through banks. ) following international quality assurance standards is important during the project installation and operation of rets. public health safety is an important issue that merits devising proper security protocols and subsequent implemen‐ tation. ) the corruption is reportedly a major roadblock for ret promotion. financing an ret project is as important as over‐ seeing original capital utilization in a project. ensuring the transparency of mechanisms at the governmental scale is a prerequisite for effectively monitoring and evaluating these projects. ) human resource development in the renewable energy domain is a necessity to prepare the next generation of engi‐ neers and scientists to undertake the associated challenges. introducing renewable subjects at graduate or post-graduate levels and offering lucrative scholarships and stipends in re‐ newable research are also important. ) the government must benefit from international collab‐ oration in ret research and development. no barrier has been reported on the transfer of technology (tot) for rets internationally. the only barrier is the lack of coordination, planning, and diplomatic drive to explore tot possibilities. iv. conclusion and future work the global drive to abandon fossil fuel based electricity and opt for renewable alternatives is imperative. the devas‐ tating environmental impact of the fossil fuel industry is a huge reason for the world to mount a concerted campaign for renewable alternatives. the fukushima daiichi nuclear disaster was a watershed moment for the power industry to evaluate the ecological repercussions of producing unsafe electricity. developed nations have accelerated the enterprise to tap as much of the renewable energy potential as feasible. china, japan, the usa, and the european union in particu‐ lar lead on the renewable energy front. denmark nearly elim‐ inates foreign fuel imports by employing % wind-generat‐ ed electricity, and germany credits % of its electricity to strengths threatsopportunities • excessive reliance on thermal generation high per-unit generation cost • • inefficient utilization of domestic resources performance of state owned institutions transmission network and transmission and distribution losses • • • potential of renewable energy generation 	solar, biomass, wind, hydro) fossil fuel (domestic coal reserve and opportunity of building gas infrastructure) • • distributed generation (using solar and biomass) sg• swot analysis weaknesses fig. . swot analysis of pakistan’s energy system. journal of modern power systems and clean energy, vol. , no. , march renewable means. pakistan is a developing country, and a sustainable elec‐ tricity supply plays a pivotal role for the economic growth of the country. besides hydro power, fossil fuel-fired power plants are a major source of electricity generation. there is insufficient fuel in pakistan, so electricity production exclu‐ sively relies on foreign imported fossil fuels. however, floods in and kashmir earthquake in exposed the vulnerability of centralized power generation and distribution of the country after natural catastrophes. pakistan’s nuclear power plants are situated on a seismic fault line and are threatened by a potential meltdown. the development of chi‐ na-supplied nuclear plants near karachi is capable of jeopar‐ dizing the health and safety of a coastal population of million people. all these facts lead to a singular conclusion: a sustainable, decentralized, and secure power source is im‐ perative for the collapsing energy infrastructure of the coun‐ try. res offers a promising future, considering pakistan’s dynamic climate and geographical location. hydro power projects serve as the second largest energy source of the country, after fossil fuel based power facilities. the coastal areas of the country possess a natural wind corridor with im‐ mense power production capability. the solar irradiation re‐ ceived by bahawalpur region is sufficient to overcome the persistent energy deficit of the country. the national agenda of priority-based renewable energy generation is of para‐ mount importance in overcoming the power 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[ ] w. aslam, m. soban, f. akhtar et al., “smart meters for industrial en‐ ergy conservation and efficiency optimization in pakistan: scope, tech‐ nology and applications,” renewable and sustainable energy reviews, vol. , pp. - , apr. . sidra kanwal received the b.s. degree in electronics engineering from uni‐ versity of engineering and technology, peshawar, pakistan, in , and the m. s. degree in electrical engineering from comsats university islamabad, abbottabad campus, pakistan, in . currently, she is a ph.d. scholar in electrical and computer engineering department of comsats university is‐ lamabad, abbottabad campus, pakistan. her research interests include re‐ newable energy systems, nonlinear control, and energy management systems. bilal khan received the ph. d. degree in electrical engineering from the university of sheffield, south yorkshire, uk, in . currently, he is an assistant professor in electrical and computer engineering department of comsats university islamabad, abbottabad campus, pakistan. his research interests include nonlinear control, optimization, smart grid, and energy man‐ agement systems. muhammad qasim rauf received the b.s. degree in electronics engineer‐ ing from university of engineering & technology, peshawar, pakistan, in . he is curently pursuing the m.s. degree in electrical engineering from capital university of science and technology, islamabad, pakistan. his re‐ search interests include smart grid control system design and state estima‐ tion of battery based systems. qst .tmp productivity growth and input mix changes in food processing adesoji o. adelaja to examine productivity growth in new jersey’s food-processing sector, this study conducts a joint analysis of total and partial factor productivity indexes. results indicate growing material intensity, declining labor and capital intensities, and relatively slow material productivity growth. however, due to the high cost share of material inputs, material productivity growth contributed more to total factor productivity growth than did growth in the productivity of any other input. in fact, almost half of the growth in overall productivity is attributed to material productivity growth. results also suggest that the decline in total factor productivity was characterized by greater decline in material productivityy than in the productivities of labor and capital. changes in labor and total factor productivity have been the focus of several studies on the u.s, food- processing sector. results of these studies gener- ally indicate that while labor and total factor pro- ductivity increased over time, both declined in and in the period immediately following. the temporary declines in these productivity indexes have been attributed to the supply shock resulting from the energy crisis (lee; jorgenson, gol- lop, and fraumeni; heien). a major limitation of these studies, however, is that they ignored ( ) the behavior of productivity indexes for nonlabor in- puts and ( ) the effects of energy prices on such productivity indexes. in most manufacturing industries, labor inten- sity is high. in conducting productivityy analysis in these industries, it makes sense to focus on labor productivity. in food processing, however, mate- rial inputs account for over of production cost (adelaja ). it does not make intuitive sense for productivity studies to focus on labor produc- tivity because material productivity growth is probably more relevant than labor productivity growth, and gains in material efficiency are likely to have greater effect on total factor productivity growth than do gains in labor efficiency. knowledge of the behavior of productivity in- dexes for nonlabor inputs and of the contributions adesoji . adelaja is an assistant professor in the department of agricultural economics and marketing, cook college, rutgers univer- sity. the author wishes to thank susan howard for her word-processing assistance. new jersey agricultural experiment station publication no. - - - , supported by a grant from the new jersey department of agriculture and state experiment station funds appropriated under the hatch and mcirnire-stennisacts. of these indexes to total factor productivity growth is useful to economists in understanding the nature and sources of productivity growth in food pro- cessing. information on the impact of energy price shocks on productivity indexes for nonlabor inputs could also contribute to knowledge about the role of energy inputs in the food-processing sector. ag- ricultural economists should particularly be inter- ested in productivity indexes for material inputs because % of materials used in u.s. food pro- cessing are farm products (adelaja ). that is, material productivity indexes should reflect the dy- namics of the efficiency of use of farm products in food processing. for example, the contributions of efficiency gains in material use to total factor pro- ductivity gains should be of interest to agricultural economists. using the state of new jersey as a case study, this paper estimates and analyzes changes in total factor productivity as well as productivity indexes for four classes of food-processing inputs: produc- tion labor, nonproduction labor, capital, and ma- terials. for each year in the - period, these productivity indexes are derived for the aggregate food-processing sector (sic ) and for each sub- sector (three-digit sic categories). to facilitate decomposition of growth in total factor productiv- ityy indexes into growth in partial factor productiv- growth in new jemey’s food-processing sector has been slower than in ttre u.s. new jersey’s shares of u.s. food-processing employment, value of shipments, and value-added fell from . , . %, and . % in the early s to . %, . %, and . %, respectively, by . new jersey’s share of u.s. population remained constant at . % during this period (annual survey of manufacturers,u.s. department of com- merce). april n.iare ity indexes, the theoretical relationship between the two is derived. this decomposition allows one to observe the extent to which efficiency gains in the use of a specific input contribute to total factor productivity growth. by further focusing on pro- ductivity changes in the – period, the im- mediate impacts of the energy crisis are further examined. results illuminate the structure of pro- ductivity growth and some of the implications of such growth. the plan for the rest of this paper is as follows. the theoretical relationships between total and par- tial factor productivity indexes are derived in the following section. the empirical model used in productivity analysis and decomposition appears next followed by a discussion of the data and the empirical results. the final section presents con- cluding remarks. total and partial factor productivity indexes denote the total factor productivity index for the tth period as tfpt and the partial factor produc- tivity index for the ith input in the t th period as pfpi,. tfpt indexes reflect overall efficiency gains (in the utilization of all inputs). on the other hand, pfpi, indexes reflect not only efficiency gains in the utilization of specific inputs, but also changes in input mix due to technological biases and input substitution. because tfpt and pfpi, are related under certain conditions, one can decompose changes in overall efficiency into changes in effi- ciencies of each input. this decomposition proce- dure is outlined in the rest of this section. assume the existence of a production function relating inputs to output (q). further assume com- petitive input markets (cp) and constant returns to scale (crs). following the convention in the an- nual survey of manufacturers (asm) and census of manufacturers (cm), also assume four catego- ries of inputs: ( ) production labor (l), nonproduc- tion labor (r), material inputs (m), and capital (k). denote the quantities used of these inputs in time period tby xl,,xri,x~,, and x~, so that x~is a vector of input quantities (xi) in period t.for the tth period, denote the price of the ith input as pi, (e.g., price of material inputs is p~j and out- tfp,is the ratio of output (q,) to the quantity of aggregate input in the tth year, it shows changes in aggregate input when output is held constant, pfpi,is the ratio of output (q,) to the quantity of the ithinput (x,) in the fth year. it shows changes in the input’s quantity when output is held constant, materials include inputs that are completely exhausted in produc- tion. nonpruduction labor includes management and service-type work- ers. put price as p.q,..the production function can be specified irnphcltly as ( ) q, = fjx, j in ( ), tt is the value of a trend variable in the tth period. it is therefore a proxy for technology. following evenson, landau, and ballou, obtain where fit = aqjdxi, equals the marginal product of the ith input in the tth period. profit maximi- zation implies that fi, = pi~p~,. hence, n pi, dxj, ( ) ~.dtr=~~-~ . dtt + ftc“ dtt, t i=l ‘ and si, is cost share of the ith input in the tth period. under crs, p~,q, = ~~=, pi,xi,, and z:= i si,= . tfp growth rate (t~p,) is — ft, ‘ ) ‘fp’ = z “ ‘t: n nnqf dlllxi,.— . at, ‘ dtt-~si,~”dtt i= = of - ~ si$i,. i= productivity growth rate of \he ith input (p~pi) is dln(qjxij ( ) pfpi, = atl . dtt alnqt i)lnxi, =—. dtt–~”dtl at, / the simple unweighed average of the pfpi, growth rates (a=pj is adelaja productivity growth and input mix changes in food processing from ( ) and ( ), note that n according to ( ), apfpt k output growth rate minus simple average growth rate of inputs, while t~p, k output growth rate minus weighted aver- age growth rate of inputs. derive the following from ( ): n n i= n hence, t~pt k the weighted average of p~pi, val- ues, while #@pt k the simple average. the dif- ference between a~pt and t~pt k defined as fol- lows: ( ) the contribution of growth in the productivity of the ith input to total factor productivity growth is obtained from ( ) as s#~pi,. the proportion of total factor productivity growth that is due to growth in productivity of the ith input (ci) is there- fore obtained as ( ) sip=i, ci=— t~p$ no& that ~., ci = under~rs, if (q~x~) > (q/x~), then ~~ > ~~ and x~/x~ > . hence, changes in input ratios are reflected by differences in partial factor productivity growth rates. partial factor productivity indexes can be used to charac- terize changes in input intensitv via intensitv mea- sures (w), ‘defined ‘as follows:- ( ) wi,= in ( ), ivi is the change in the intensity of input i in time pe~od t and iui is the absolute value of u. if wi, > (ivi, < o), production becomes more (less) input i intensive over time. note that z?= ~ ivi,= o. empirical model the analysis in the previous section is in continu- ous time. however, it is difficult to calculate pro- ductivity indexes from continuous time-series data since both si and xi change between periods. to solve this problem, jorgenson, gollop, and frau- meni recommend discrete approximation via the logarithmic indexing method (lim), lim is con- sistent with the translog production-function spec- ification of the implicit production function in equation ( ). following jorgenson, gollop, and fraumeni, define t~pt as the average growth rate of tfp between two discrete points in time, say time pe- riod (t) and (t – ). that is, t~p, k approximated by tfpf = y [tfp, + tfp,. ~]. further define s* as the average factor shares of the ith input b&ween two discrete points in time. that is, st = %[si, + si,_,]. considering that tfpf k also the difference between successive logarithms of output minus the weighted average of the difference be- tween successive logarithms of inputs with the april weights being the s~s (christensen, cummings, and jorgensen), it can be obtained as ( ) tf~ = lnq, - lnq .l - ~s: [lnx,, - lnx ] ,., i= . qt - i s,~;, i= where q~ = lnqt – lnq,_, and x; = lnxi, – lnxi,_,. note also that ( ) @ = tfp? + ~ s,$y$. i= equations ( ) and ( ) show the traditional tfp decomposition relationship. crs and cp are imposed on the translog pro- duction function via the constraint that ~~~ ~si = . this constraint allows one to define tfp growth rate as the weighed average of partial factor pro- ductivity growth rates (see equation ). these as- sumptions are not required to use lim. however, they are required to use the tfp decomposition relationship in equation ( ) since the relationship is based on the premise of crs and cp. crs and cp imply that the constraint =, si = must be imposed in using the lim procedure. this is equivalent to the constraint that = ~ s? = . imposition of the constraint is further discussed in the data section. p~pi, is approximated by pfp~ = [lnq, – lnq,_ ~] – [lnxir – lnxi,_,] = q: – x~. hence from ( ), ( ) pfp~ = ~ – x; n– njare n– ( ) tff# = pfp; - ~ s~x$- x ],“ i=l using ( ) and ( ), tfp~ and pfp~ can be cal- culated from time-series data on real quantities of outputs and inputs, and cost shares of inputs. in- dexes of tfpt and pfpi{ can be further con- structed. the relationships m ( ) through ( ) also armly to the tfp and pfp indexes obtained via d~~c~eteapproximations posed in using the lim. data and calculations if crs and cp are im- cm and asm publish annual new jersey data on value of shipments (vs), expenditures on materials (me), hours of production labor employment (l.h), wages paid to production labor (z@, wages paid to all labor (lre), number of workers (lrn), and number of production workers (ln) for the food-processing sector (sic ) and each three- digit sic category except for fats and oils (sic ). the data is consistently available for the years through . the quantity index for the production labor in- put (xl) is obtained as the index of lh. total number of nonproduction workers (rn) is calcu- lated as lrn – ln. the index of the nonproduc- tion labor input (x~) is obtained as the imputed hours of employment of nonproduction workers (rh), which is obtained by assuming that each nonproduction worker works hours per week and weeks per year. x~ is obtained by dividing me by the producer price indexes for materials and components obtained from producer price indexes (u.s. department of labor, bureau of labor sta- tistics). this data source also provides data on pro- ducer price indexes for all food products (sic ) and for each three-digit sic category of food prod- ucts. these are used as deflators for vs to obtain implicit output quantity indexes (qt). the annual cost of capital and the index of capital input in real terms (x~) are obtained from adelaja ( , ). the base yedr for all indexes is ( = ). wages paid to nonproduction workers (zw) are calculated as lre – le. total cost of production (tc) is calculated as ke + re + me + le. input shares (si) are calculated as ke, re, me, or le divided by tc so that z:= ~si = , as required adelaja productivi~ growthartdinput mix changes in food processing table . estimated productivity indexes for new jersey’s aggregate food-processing sector (sic ), -s total production nonproduction material capital factor labor labor input input year productivity productivity productivity productivity productivity so percent growth: - – – – – – – under the crs and cp assumptions. values of (pfp~) are used to obtain indexes of partial factor productivity (pfpi), while those of tfp* are used to obtain indexes of tfp. validity of the translog production-function specification is assumed. empirical results tfp, and pfpj, indexes derived for the aggregate sector appear m table . percentage growths of these indexes for the - and – peri- ods are also reported in table . for the same periods, percentage growths in tfp, and pfpi, for constraints implied by crs and cp impose strong restrictions on the characterization of food-processing technology, but they allow definition of input shares as output elasticity and definition of tfp growth rate as tbe weighted-average growth rates of pfp,. evidence of market power and price-setting behavior in food processing appears in azzam and pagoulatos, schrueter, schroeter and azzam, and connor, rogers, mar- ion, and mueller. pratten, amongst others, also provides evidence of non-constant returns to scale in food processing. these suggest that tfp, and pfp,,measures derived in this analysis may be biased. for example, tfp, would be biased downwards if production is character- ized by increasing returns to scale and upwards if characterized by de- creasing returns to scale. productivity indexes generated from implicit quantity indexes are sensitive to price variation and the choice of price deflator. the subsectors appear in table . intensity values (w) for the sector and subsectors appear in ta- ble . the aggregate sector, - table indicates that all indicators of food- processing efficiency (all productivity measures) in new jersey experienced secular growth during the - period. the % growth in tfp in the aggregate sector is tantamount to a ? material productivity growth, % production labor pro- ductivity growth, % nonproduction labor pro- ductivity growth, and % capital productivity growth. obviously, labor productivity growth alone does not provide a full picture of productiv- ity growth in food processing. these results indi- cate that economists need to examine other partial productivity indexes to fully understand productiv- ity growth. material productivity growth was relatively slow during the - period ( , compared to , y , and % for other inputs). this suggests greater constraints in increasing the pro- ductivity of materials vis-h-vis other inputs. this phenomenon can be attibuted to the strong com- plementarily between material inputs and output, april njare table . estimated percentage growth in total and partial factor productivity indexes for the subsectors total production nonproduction material capital sic factor labor labor input input codea productivity productivity productivity productivity productivity -s – – – – - – – – – – – - – – – - – – – – – - - – – – - – – – – – – – – – – – – – – – - – whe sic categories areas follows: , meat products; , dairy products; , preserved fruit and vegetable products; , grain mill products; , bakery products; , sugar and confectionery products; , beverage products; and , miscellaneous and limited short-run substitution of other inputs for materials (adelaja ). food processors seem to face less constraints in increasing labor and capital productivity. table . estimated input intensity values sic intensity measures codea iv, ivr ivm iv. - - . . – . . . . – . – . . – . – . – . – . . . – . . . – . . - . . – . – . – . – . . – . – . . . . – . – . - . - . . – . . . , . . . . . . – . – . . . . . . – . – . – . - . – . – . – . – . - . - . – . . , – . . – . – . – . *the sic categories are as follows: , total for all food prod- ucts; , meat products; , dairy products , preserved fruit and vegetable products; , grain mill products; , bakery products; , sugar and confectionery products; , beverage products; and , miscellaneous products. in spite of limited material productivity growth, material productivity’s contribution to total factor productivity growth should not be downplayed be- cause of materials’ high cost share. material pro- ductivity’s true contribution to total factor produc- tivity growth is the product of the average material factor share (. ) and total material productivity growth ( %), divided by total factor productivity growth ( %). hence, material productivity growth alone contributed % of the % growth in total factor productivity ( . % tfp growth). this significant contribution to total factor produc- tivity growth accrues from waste reduction, recy- cling, production of by-products, etc. (adelaja ). capital productivity growth was rapid during the - period. hence, capital intensity declined. material intensity increased, however, suggesting that materials were substituted for capital (see ta- ble ). production labor intensity increased while nonproduction labor intensity decreased (see table ). hence, nonproduction labor productivity growth outpaced growth in production labor pro- ductivity. the apparent substitution of production for nonproduction labor is consistent with oi’s ar- gument that less capital-intensive technologies re- quire less management and nonproduction work- ers, and more production workers. apparently, as production became less capital-intensive, the rela- tive demand of new jersey food processors for nonproduction labor, much of which is manage- ad.daja productivity growth and input mix changes in food processing ment labor, declined. overall, the changes in input mix in the sector were toward less nonproduction labor and capital intensities, but greater production labor and material intensities. the declining new jersey shares of u.s. food- processing activities have been attributed to chang- ing transportation economics, increasing costs of acquiring raw material locally (due to declining local supply of farm products), stringent waste- disposal regulation, and high fixed costs of pro- duction (e.g., higher real estate costs) in new jer- sey (lopez and henderson). adelaja ( ) ar- gued that slower tfp growth in new jersey food processing, relative to the rest of the u. s., also made new jersey a less attractive location. results of this study provide additional information on new jersey’s food-processing industry. specifi- cally, the results explain the input mix changes and productivity growth that accompanied the de- cline of new jersey’s share of food-processing ac- tivities in the u.s. the subsectors, - note that material productivity increased in all subsectors except the beverage group, which is highly material-intensive. the trend in beverage production in new jersey has been from full pro- cessing to the mere dilution of concentrates shipped in from other states (adelaja ). hence, the significant increase in material inten- sity and the decline in material productivity in bev- erage production is not surprising. consistent with aggregate-sector findings, ma- terial productivity growth was outpaced by growth in other inputs’ productivities in four of the eight subsectors (dairy, bakery, sugar and confection- ery, and beverage). material intensity increased in these same subsectors. material intensity also in- creased in the preserved fruit and vegetables, grain mill, and miscellaneous-products subsectors. con- sequently, the only exception to increased material intensity is meat processing, where material pro- ductivity growth outpaced growth in productivities of other inputs. the relatively rapid growth in ma- terial productivity in the meat subsector may re- flect greater incentives to implement material and waste-reducing technologies due to the heavy reg- ulation of material waste from meat processing. consistent with the pattern for the aggregate sector, capital intensity declined in all subsectors, but capital productivity increased. growth in non- production workers’ productivity exceeded that of production workers’ productivity in most subsec- tors. the w values fiuther suggest that production labor was generally substituted for nonproduction labor. this is consistent with the finding for the aggregate sector. contrary to the trend for the ag- gregate sector and most subsectors, production la- bor productivity actually declined in the meat (sic ) and grain mill (sic ) subsectors. the n’ values indicate that in both subsectors substitution of production labor for nonproduction labor was significant. the relative growth rates of tfp are worth not- ing. for example, tfp growth was most rapid in the bakery subsector ( % gain). bakery was fol- lowed by sugar and confectionery ( % gain), pre- served fruit and vegetables ( y gain), dairy and beverage ( % gain), and miscellaneous products ( % gain). grain mill products experienced the least gain in total factor productivity ( % gain). tfp gain in meat production was also limited (lo%). the energy crisis given some of the recent events in the middle east, there is growing concern among economists that drastic shocks in energy prices, similar to what happened in , might again occur. changes in intensity values and productivity indexes in should generally reflect potential impacts of future energy price hikes on productivity and the struc- ture of production. in the aggregate sector and all subsectors, total factor productivity declined dras- tically in . similarly, all partial factor produc- tivity indexes declined in , except in the case of production labor productivity, which declined in grain mill production. it appears, therefore, that because they result in greater declines in output than in inputs, energy price shocks are usually pro- ductivity-dampening in the short run. the excep- tion in the case of grain mill production is difficult to explain. in the aggregate sector, material productivity fell more than did productivities of other inputs in . hence, material intensity increased, while the intensities of other inputs declined. producers therefore seem less capable of reducing material consumption (compared with other inputs) when energy price shocks occur. this is an indication of the strong complementarily between materials and output. apparently, recessions resulting from en- ergy price shocks would result in greater labor and capital unemployment than in material unemploy- ment. this implies that farmers are not as likely to get hurt as would suppliers of other resources to the food-processing sector when energy prices surge. in the aggregate sector, the energy crisis re- sulted in greater unemployment of nonproduction april njare than production workers. this is not surprising considering that the former are more highly paid and that the energy crisis also reduced capital in- tensity. greater unemployment of nonproduction than production workers is likely to accompany future increases in energy prices. tfp declined by % in . also, the decline in material productivity exceeded those of other inputs. following the weighting procedure in ( ), material inputs’ true contribution to the decline in tfp k estimated to be %. the impli- cation is that material productivity changes are very important, especially during periods of en- ergy price shocks. now, examine the impacts of the energy crisis on total and partial factor productivities in the sub- sectors. in the meat, bakery, sugar and confection- ery, beverage, and miscellaneous-product groups, the impacts were similar to the aggregate case in that material productivity declined more than the productivities of other inputs. also, consistent ‘with the aggregate sector case, the instantaneous effect of the energy price shock involved increased material intensity and material-capital substitution in most subsectors. in the cases of dairy, preserved fruit and vege- tables, and grain mill products, greater decline in nonproduction labor productivity than in the pro- duc~ivities of materials, capital, and production la- bor resulted from the energy crisis. hence, man- agement workers in these subsectors seem to enjoy an unemployment buffer when energy prices rise. note also from the intensity values in table that the energy price shock involved greater unemploy- ment of production than nonproduction labor in meat, dairy, preserved fruit and vegetables, and sugar and confectionery processing, while it re- sulted in greater unemployment of nonproduction than production labor in the rest of the subsectors. conclusion this paper combines total and partial factor pro- ductivity indexes in an innovative way to analyze productivity growth and input mix changes in new jersey’s food-processing industry. while it may have some limitations, the approach allows better accounting of contributions of specific inputs to total factor productivity growth. results for the entire - period suggest a % overall pro- ductivity growth and slower material productivity growth than labor and capital productivity growth. however, given the high cost share of material inputs, gains in the efficiency of use of materials explain almost half of the growth in total factor productivity. an implication of this is that material productivity growth, which is typically ignored in productivity studies, is an important component of productivity growth in food processing. capital productivity grew rapidly in the sector. simultaneously, the relative demand for nonpro- duction labor, vis-il-vis production labor, declined due to the complementarily between the former and capital-intensive technologies. information obtained on input intensities in the sector are useful in analyzing the trends in input mix and in corre- lating these with the pattern of productivity growth. such analysis is hardly ever conducted in conjunction with productivity analysis. an objective of this study was to examine the immediate impact of the energy crisis. re- sults indicate that productivities of all inputs (as well as total factor productivity) tend to fall in the short run when energy price shocks occur. the decline in material productivity exceeds the de- clines in the productivities of other inputs, while the reduction in material use is less than reductions in other inputs. hence, farmers supplying food processors are better protected than other resource suppliers when energy price shocks occur. the energy crisis also resulted in greater unem- ployment of nonproduction than production labor, suggesting that the former is more vulnerable in times of energy price increases. references adelaja, a.o. the agriculture and food complex of new jer- sey. new jersey agricultural experiment station publica- tion no. sr- - - . june . adelaja, a. o. “material productivity in food manufactur- ing. ” american journal of agricultural economics , no. ( ): – . azzam, a. m., and e. pagoulatos. “testing oligopolistic and oligopsonistic behavior: an application to the u.s. meat-packing industry. ” journal of agricultural econom- ics ( ): - . christensen, l. r., d. cummings, and d. w. jorgenson. c‘eco- nomic growth, – : an international compari- son, ” in new developments in productivity measurement and analysis, edited by j. w. kendrick and b .n. vaccrrra. chicago: national bureau of economic research, , connor, j. m., r.t. rogers, b.w. marion, and w.f. mueller. the food manufacnrringindustries: structure, strategies, performance and policies. lexington, ma: lexington books, , evenson, r. e., d. landau, and d. ballou. “agricultural pro- ductivity measures for u.s. states, - . ” in evak- ating agricultural research and productivity. miscella- neous publications no. - . minnesota agricultural experiment station, university of minnesota, . heien, d.m. “productivity in u.s. food processing and dis- adelaja productivity growth and input mix changes in food processing tribution. ” american journal of agricultural economics ( ): - . jorgenson, d. w., f. gollop, and b. fraumeni. producrivi~ and u.s. economic growth. cambridge: harvard univer- sity press, . lee, d.r. “labor market dynamics in the food sector. ” american journal of agricultural economics ( ): - . lopez, r. a., and n.r. henderson. ‘the determinants of lo- cation choices for food processing plants. ” agribusiness ( ): - . oi, w .y. “slack capacity: productive or wasteful?” ameri- can economic review ( ): - . pratten, c. “a survey of economies of scale. ” in research on the “cost of non-europe, ” basic findings. luxembourg: office for official publications of the european commu- nities, . schroeter, j. r. “estimating the degree of market power in the beef packing industry. ” reviewof .ecorromicsand staris- rics ( ): - . schroeter, j. r., and a. azzam. “measuring market power in multi-product oligopolies: the u.s. meat industry. ” ap- plied economics ( ): - , u.s. department of commerce. bureau of the census. annual survey of manufacturers. various years, —. census of manufacturers. various years. u.s. department of labor. bureau of labor statistics. pro- ducer price indexes. various years.    energies  ,  ,  ; doi: . /en   www.mdpi.com/journal/energies  article    journey of american building physics: steps leading  to the current scientific revolution  mark bomberg  ,*, anna romanska‐zapala   and david yarbrough.     mechanical and aeronautical department, clarkson university, potsdam, new york, ny  , usa;    department of automatic control and information technology, faculty of electrical and computer  engineering, cracow university of technology,   cracow, poland; a.romanska@pk.edu.pl    r&d services, cookeville, tn, usa; dave@rdservices.com  *  correspondence: mark.bomberg@gmail.com  received:   january  ; accepted:   february  ; published:   february    abstract: this is an overview of a key note lecture; the quote for this lecture is from t.s. eliot: “we  must not cease from exploration and at the end of all our exploring will be to arrive, where we  began, and, to know the place for the first time”. this quote highlights that the process of scientific  development goes in circles, yet each of them goes above the previous circle, building up the ladder  of knowledge. closing one circle and opening the next may be either be a quiet, unnoticeable event  or a roaring loud, scientific revolution. building science (physics) was started about   years ago,  but only now are we closing its second circle. perhaps, because of building physics’ role in the fourth  industrial revolution, this discipline itself is undergoing a scientific revolution the first industrial  revolution was based on steam generated by burning coal, the second was based on petroleum, and  the third on electricity and concentrated electricity production. the current one, i.e., the fourth, is  based on distributed energy sources combined with information technology.  keywords: energy efficiency; building automatic control; energy use under field conditions; two‐ stage construction process; cost‐benefit evaluation; deep retrofit of residential buildings  . creating building physics ( – )  in  , a commercial thermal insulation called “pal‐o‐pack” was manufactured in saskatoon,  canada.  it  used  shredded  newsprint  with  a  small  admixture  of  lime  solution  [ ].  in  ,  this  insulation was pneumatically applied using the discharge of air from an “electrolux” vacuum cleaner  into a wood frame house. this event, a first recorded retrofitting of a wood frame house, can be  considered as the birth of the new endeavor that became very popular   years later.  within  the  s,  the  university  of  minnesota  introduced  the  weather  barrier  (asphalt  impregnated kraft paper), and the university of wisconsin introduced the first water vapor retarder,  because adding thermal insulation in the wall cavity created a new problem. it lowered a dew point  inside the wall causing a winter condensation of water vapor. so, in  , we had all the elements of  building physics: materials for environmental control, moisture problems created by condensation of  water vapor, and first methods for calculating the drying rates of walls.  . simplification and stagnation in building physics ( – )  the  theoretical development of building physics  took place  in germany and russia, where  several published books dealt with the thermal stability of buildings [ , ] and calculations of masonry  drying  [ ].  as  the  post‐war  construction  boom  introduced  changes  in  housing  and  new  wood  products increased the airtightness of wood frame houses (called timber houses in germany), the  presence of excessive condensation became apparent.    in  , glaser explained, with help of simple graphics, what scientists had known since    [ ]. yet, his explanation, in a time of visible condensation, was translated from german into different  energies  ,  ,     of    languages and enshrined in various standards. the condensation actually happens, but water and  vapor continue moving on, making the calculations based on glaser theory null and void.    this situation highlights that an easy to understand explanation of a perceived problem stays in  the mind better than a description of the problem’s complexity. to explain the real phenomena in  materials, over the course of a decade (until the mid‐ s), the lund university team [ , ] published  experiments, and developed two simultaneous heat and moisture transfer models, but to no avail.  the era of building physics stagnation was firmly established.  the simultaneous transfer of heat and mass (the latter being: moist air, water vapor, liquid water  attached to material surface, and liquid water with entrapped air bubbles in large voids of material),  i.e., a standard interacting heat and mass transfer in porous materials, was too complex in comparison  to the simple graphics of glaser’s. in  , during the meeting of the international heat and moisture  transfer committee (cib w ) in washington, usa, delegates from all countries tried to convince  german colleagues that one cannot use glaser theory, even with a variable vapor transfer coefficient.    the rescue came   years later, when a model [ ] that was close to  s swedish models got  commercial recognition, sufficient enough to make an impact in this field. as a curiosity, in  , the  author, who was  invited  to  teach a course of building physics  in poland, was  told  that  the eu  curriculum requires teaching glaser’s theory—he replied: “of course, i always teach it, as an example  that you cannot simplify the nature of phenomena, before you understand it.”  . new objectives give building physics new life ( – )  with building physics following a group of ignorant people, north america followed professor  neil b. hutcheon [ ], who, in  , when invited to give a talk at building research institute in india,  said:  “knowledge about building, called, for convenience, building science is valuable largely  because  it  is useful  in predicting  the outcome of  the result of some building situation.  rational design is possible only when there is a capability to establish, each time a choice is  made, the probability of a particular result.”  hutcheon explained that predictability of performance requires both the trained professional  (buildability depends on the designer) and a method (that can be based on tradition, testing or an  integrated test and model), but this method must involve:   the environment   adjacent materials in the assembly   on‐site factors (workmanship)  nevertheless, the impulse for a real change came from another unusual event highlighted in  figure  .  the energy crisis of   brought to people’s attention that petroleum, while plentiful today,  must be considered as a finite resource. the gloom that it forecasted in   did not happen; yet the  people’s attitude to energy was slowly changing. while the airtightness of houses in canada in the  years   to   and   to   was practically the same, varying in the range of   to   ach,  that measured in the years  –  was between  .  and   ach, when tested at   pa pressure  difference.  this implies that the energy crisis brought the northern housing (sweden, canada) to an average  . – .  ach at   pa pressure. using exponent n =  .  in the pressure equation for recalculation,  one obtains  .  to  .  ach at   to   pa pressure difference (i.e., a practical service range), that  describes a requirement for people’s breathing.    in  , researchers at illinois tu designed a low energy house and in  , in the province of  saskatchewan in canada,   houses were built along their concepts. a demonstration house for this  new technology (figure  ) was built in regina, province of saskatchewan, canada.  energies  ,  ,     of    figure  . for a few days during so‐called energy crisis, all private cars were banned in some eu  countries (holland is shown in this picture, source unknown).    figure  . saskatchewan energy conservation house designed by the illinois u demonstrated passive  technology in   (regina). solar exposed surface with large windows is slightly inclined. evacuated  solar  pipes  are  placed  on  the  attics  level.  it  was  provided  with  air‐sourced  heat  pump  and  polyethylene‐based heat recovery ventilator. reprinted with permission of harold orr.  one may be surprised to see that   years ago we had almost current technology. this then begs  the question: why was this technology not used in the market place?    primarily because there was no real contact between the building science and the socioeconomic  forces driving the evolution of building construction. the design and construction shown in figure   represented the idea of building science leaders in north america, but the construction industry  was not prepared  to  follow, because  it did not see  the need. the gap between building science  (physics) and builders was then, and is today, a critical issue that slows progress in climate change  reduction [ ]. builders, however, respond to what the public wants them to do. effectively, as our  university does not teach a holistic view of society and technology, it takes time to develop a grass  root understanding. recently, while talking with harold orr, we agreed that   years ago we had the  knowledge of the technology, but not the understanding of building performance.  this question was analyzed in the paper [ ] and the following observations summarize the  difference between then and now:    . heat, air and moisture transports are inseparable and cannot be assessed in separation from each  other. today, we talk about “environmental control”.  . often, when in practice one modifies materials or construction details, one finds that the cost of  repairs following these minute changes is significant. this happens each time when we analyze  energies  ,  ,     of    only the detail itself and forget about its interaction with the other elements of the system [ ].  in other words, we fail when we lose track of the holistic approach.  . the modification of details in the building enclosure is slow but continuing. note that leaky  and  poorly  insulated  walls  dried  quickly.  airtight,  insulated on exterior, walls are drying  slowly. if water enters around the window frame, it will stay inside the wall. this highlights the  need for an environmental control design.  . building physics followed the evolution of practice [ ] and lessons from any solution of the  encountered problems enhanced understanding of construction performance.  yet, in the  s there was no practice of low energy housing construction and, timusk [ ],  when reviewing moisture control issues of the previous decade, stated:  “at  the moment we are  in a position where  the  traditional approach of  learning  from  failures  and  copying  what  worked,  has  broken  down.  ….it  is  extremely  difficult  to  accommodate all of the new information in view of the rapid changes in materials, details  and performance expectations.”  the paper [ ] refers to the canadian r‐  and build america programs as a guide for the  future design of housing, highlighting that university education must be complemented by seminars  for consultants and building practitioners. indeed, this became the widespread practice in the usa.  furthermore, the white paper [ ] states:    “we need to expand the approach of environmental control in two dimensions:   improve the tools of field monitoring and field diagnostics and integrate them with  user‐oriented, computer‐based design tools,   stress the objective‐based design process much in the same manner as it is done in the  structural engineering.”  note, in the legal language of canadian code, the word “performance” is replaced by the word  “objective” to avoid separation between the concepts of properties and performance. we, however,  use “performance”, as it is defined for high performance buildings in the   us congress “energy  act”. the new performance expectations emerged slowly, and mainly as an effect of the accelerated  pace of building physics discoveries. here are a few critical performance issues:  . discovery of interstitial air pressure fields [ – ]    . introduction of air barrier systems [ , ]  . the need for exterior insulating sheathing [ ]  . an ecological complex in the field performance [ ]  . introduction of an integrated design process [ ]  . capillary active technology to modify humidity in indoor air [ ]  the key observations in item   were:     there may be several airflow paths between any two points in a structure     the total airflow resistance is a sum of all local airflow resistances,     the total airflow resistance decides in which way most air goes,   the presence of interstitial airflows permits the mechanical equipment to modify air pressure in  the indoor spaces, as well as to modify the thermal performance of walls   as airflows carry water, they further impact the thermal performance of walls  in summary, we have the following four types of airflows in building [ ]:  ( )  exterior (caused by wind)    ( )  interior (hvac operation and ducts)  ( )  across the walls (stack effect)  ( )  interstitial (connectivity walls, rooms, staircases, ventilation plenum)  energies  ,  ,     of    one should observe that the impact of interstitial pressure field became significant only when  the building enclosure becomes more airtight. figure   highlights the effect of interstitial air pressure  field in mold growth on an interior wall in florida.      figure  . interstitial airflow results in mold growth on the interior in a florida hotel reprinted with  permission of dr. j. w. lstiburek.  another practical observation is explained in figure  .    figure  . effect of a thermal insulating sheathing compared with the case of cellulose fiber insulation  discussed in stage   (from author archive). effectively, during the third development stage, the difference between building physics and  science disappeared; on  the request of  the architect general  for  the us, soon  this discipline of  knowledge will be taught in american schools. hopefully, in europe, more attention will be paid to  the practical know‐how necessary for an academic discipline to have an impact and an engineering  value.  the  introduction  of  integrated  design  processes  and  post‐occupancy  commissioning  is  a  breakthrough that has initiated a new development of building science.  at the moment, the framework for the quality assurance in construction is very shallow. in the  author’s opinion, there  is a  legal framework, but also a  lack of field performance modeling and  testing. nevertheless, the mere recognition of the need for a holistic approach to the integration of  technology and the request to map the quality assurance in design stage is the step forward necessary  to continue the progress of building performance based qa.  figure   presents the last of the critical elements in the progress of building physics, namely,  introduction of the capillary active layers.    energies  ,  ,     of      figure  . explanation of the capillary active layer (cal) reprinted with permission of peter haeupl  [ ].  effectively, the wide scope of technological developments in stage   permits us to define stage    as  the opportunity  for ensuring  that  the holistic  technology  is going  to reach  the needed socio‐ economic impact.  . towards the socio‐economic impact of the building science ( – )  modern buildings have eliminated the effect of thermal mass on energy consumption through:   large areas of glazing, combined with leaky wall window interfaces that increased both air and  solar energy transfer across the wall     a high precision in the control of indoor air temperature that eliminated dynamic performance  we must observe that a large area of glazing delivers solar radiation to the floor and an effective  air re‐circulation system is needed to remove this heat. as air has a much smaller heat capacity than  water, one recommends employment of hydronic systems built into the floors or walls. this is more  efficient than airborne systems [ ].    forty years ago, energy consumption in new residential buildings in north america was  –  kwh/(m ∙y), and today this is about  % less, and advanced buildings use about  % of the  original number—  kwh/(m ∙y). such a high efficiency of the building enclosure will make solar  exposed rooms over‐heated while other rooms still require heating. for simultaneous heating and  cooling, the best method is a heat pump with one or two buffer tanks. the hot tank is also integrated  with solar thermal panels that are typically placed as an outer skin in the wall facade, or as a shading  device above the solar‐exposed windows.  the integrated design process (idp), in the conceptual design stage, should include four critical  steps:    step   includes space organization, passive measures and factors affecting indoor environment  such as thermal comfort, indoor air quality, acoustics, daylight, illumination, hot and sewer water  management, aesthetics and building resilience.  step    deals  with  the  building  automatic  control  system  that  integrates  heating,  cooling,  ventilation, and other indoor climate controls including the geothermal and solar means for energy  generation and storage.    step   provides an economic analysis to determine the level of investment that limits the  st  stage of new construction or retrofitting.    step   develops a comprehensive operational manual for the building and provides the design  and cost for stage   of the new construction or retrofitting.    energies  ,  ,     of    . . example of a new technology  engineering practice prefers to highlight technology on its application examples. even though  this example may be modified each time when a new design is made, the example discussed in the  following section provides a better insight into the significance of different factors.    we propose the use of an adaptable interior climate that allows temperature changes of   °c per  hour and up to   °c per day, during either summer or winter. experience with some zero energy  buildings in the us indicated that air re‐circulation is a critical component needed for temperature  equalization in different rooms. to this end, we discuss:   individual ventilation on‐demand in rooms with solar heating.   using a hybrid ventilation system with overpressure of the supply air. in this case, one must  improve the moisture management in the walls.  using a periodic overpressure on the supply air induces airflow from the supply point to the  kitchen and bathroom exhaust points and the natural ventilation, as long as a pressure difference  exists  in  the  indoor space. after  the air pressure equalization, both  the supply and  the exhaust  ventilation will start operating. an air handling unit delivers a part of the return air to the supply air.    the fraction of outdoor air needed for the supply air depends on several factors such as number  of people  in the space, function of the space, floor area, temperature of the outer air, difference  between outdoor and indoor air, or difference between preheated and indoor air, and even the season  of the year. the latter is because we use minimum ventilation in some periods of the year but over‐ ventilation in others. experience from the high environmental performance house [ , ] indicated  that fresh air could be delivered only for   min during each hour, and for   min the air should be  re‐circulated and the natural ventilation could also last for up to   min.  during the building retrofitting, one provides a partial air gap between the old wall and the  additional thermal insulation on the interior that will be used for ventilation channels. we are talking  about dynamic or ventilated walls. this concept is not new and studies on dynamic walls in centre  recherche’ industrielle de rantigny (crir), france, in the  s, showed that the difference between  thermal resistance of the wall exposed to static or dynamic performance was negligible.  so, when the wall acts as a ventilated heat exchanger, covering the wall surface with capillary  active materials can create a new method for moisture management. the air gap is contained between  a capillary active layer on the exterior side, and interior thermal insulation is provided with a water‐ vapor retarder. in cold climates, in the winter, the interior relative humidity is typically below  %,  so air passing through a major part of the wall height will slowly remove moisture from the old wall  after the retrofit has been completed. at the same time, the capillary‐active layer is designed so that  it enables the transport of moisture from the existing wall to the ventilated space [ ].  dynamic operation of heating, cooling and ventilation systems is controlled by a control system,  but there is a major control problem, namely a lack of field performance models. as we discussed  elsewhere [ ], currently used energy models are parametric and the eqm technology requires a real‐ time control under variable climatic conditions. the eqm control system collects information from  all subsystems and uses advanced control algorithms to set parameters for heating, cooling, and  ventilation based on indoor and outdoor climatic conditions.    as heating/cooling pipes are located in the walls, the water flow and temperature sensors must  also be placed there. some rudimentary control algorithms may be delivered with the equipment,  but fine tuning (optimization of the heating/cooling or ventilation devices) will be done during the  operation of the system. for this purpose, the building automatic specialist must be incorporated in  the design team.  . . two‐stage design process  figure   shows that the integrated design process (idp) invariably starts with lowering utility  bills without cost increase and that all passive measures create only a small increase in the ownership  cost that is here expressed as mortgage [ ]. with increased use of these measures, the ownership  cost (mortgage cost plus utilities) passes through a minimum. there is another characteristic point  energies  ,  ,     of    on the curve shown in figure  , namely a point of equilibrium in which the use of photovoltaic (pv)  panels is the same as traditional passive measures.  one may continue until reaching zero energy at a substantial mortgage investment, typically  about  – % increase of the minimum cost. the typical investor will not go that far, and one stops  after placing a few solar panels.    thus, the rational design of low energy buildings hinges now on the capability of selecting the  reference point for the photovoltaic (ph) technology. in line with this need, the american ph institute  selected reference buildings based on  the ashrae/doe climate zones  [ ] and considered    locations for cost optimization that included air tightness, window upgrades with a  °c minimum  interior surface temperature, heating and cooling demands, and peak heating and cooling loads.    statistical models were fit so that the cost of the target properties can be generated for any  location from parameters such as degree–days and design temperatures. in this manner, both the  german  and  american  ph  developments  moved  housing  toward  the  goal  of  sustainable  development, but have not yet reached the goal.    figure  . costs of utilities (green) and mortgage (blue) versus energy savings from zero to  %  savings.  point    denotes  the  start,    the  passive  measures  alone,  and    the  beginning  of  pv  contribution (with permission of wright & klingenberg [ ]).  figure    illustrates  that  investors making  the cost–benefit analysis stop  investing when  the  return on investment reaches a prescribed level. this is typically somewhere between   and   years  and in figure  , it falls between points   and  . yet, this is far below that of the zero‐energy building.  the best way to alleviate this conflict would be to introduce a two‐stage construction process.    in such a process, stage one is designed to achieve a performance level limited by a selected cost,  while stage two continues to the selected performance level and has a predefined scope of work and  cost. in the first stage, the building is completed at a minimum performance level that is acceptable  to both the building code and the investor, yet the design predicts continuation of construction to the  zero energy level.    the second stage starts a few years later, and completes already designed actions to the required  performance level. in many instances, the zero level will also include the night charging vehicles used  in the household. for the two‐stage solution to be successful, one must design both stages at the same  time, and the construction process is only divided into two parts to secure funding when the basic  level of the building is in existence.    figure   shows the application of a multi‐stage construction process in a building cluster called  “atelier rosemount” in montreal [ ], that included a mix of different types, e.g., social or ecological  dwellings.  initial  construction  began  in    and  stepwise  upgraded  until  reaching  %  of  the  cumulative reduction   years later. the retrofitting included the following steps:     high performance enclosure; common water loop; solar wall— % reduction     gray water power, the cumulative energy reduction grows to  %  energies  ,  ,     of     heat pump heating—all passive measures give a  % reduction   domestic hot water with evacuated solar panels, a further  %   photovoltaic panels reduce the total energy to a total of  %  this project highlights that modern thinking in construction eliminates the boundary between  new construction and the retrofitting of old buildings.    figure  . stages of improvements from   to   in atelier rosemount, montreal [ ] (reprinted  with permission of cmhc and credit l’oeuf s.e.n.c.)  assume that in the first stage of building, or before retrofitting program, your heating/cooling  bill is us$  a month or us$  a year, and you intend to upgrade to zero energy in two years. in  stage one, or in retrofit estimate, you have the total cost of the retrofit equal to us$ , . , and you  will be asking for a us$ ,  loan. taking us$ ,  out on and a  %  ‐year second mortgage gives  you a monthly payment of us$ , but your saving is us$ –  a month, i.e., us$ .  a month.  your borrowing cost is us$ , , so it is paid after   years and   months.  currently in the us, a number of financial institutions will provide a loan based on existing  capital resources and the federal government is in the process of revising the appraisal documents  for buildings. all that a homeowner needs is a detailed cost of stage two to reduce energy expenses.  as lenders calculate a borrower’s expenses as principal, interest, taxes, and insurance (piti), adding  energy bills to their calculation (piti+e) opens up an interesting new investment opportunity.    we must observe that this investment does not increase the cost of living, as the local economy  gets a boost, and yet co  emissions are dramatically reduced. a win‐win‐win situation.  finally, figure  , published   years ago, reminds us that to reach   targets, one must put  retrofitting as a priority. we are glad that horizon   in europe came to this conclusion and would  like to highlight that while a permit for new buildings requires a lot of decisions, interior retrofitting  requires only one—when to start it.    energies  ,  ,     of    figure  . the need for retrofitting existing buildings. reprinted with permission of lawrence berkeley  national laboratory.  . steps to the scientific revolution  kuhn [ ] spoke about a small step that makes the previous development take a new form, calling  it a scientific revolution. in the opinion of the author, a two‐stage construction approach combined  with a dynamic operation of functionally integrated (or smart) buildings is also going to provide a  scientific revolution. the two‐step construction approach links the financial security of investment  with the social need for the accelerated reduction of carbon dioxide.    to the previously listed technology development, namely:     discovery of interstitial air pressure fields   introduction of air barrier systems     the need for exterior insulating sheathing     an ecological complex in the field performance   introduction of an integrated design process     capillary active technology to modify humidity in indoor air  we are adding the following measures of the occupant centered control (occ) of the indoor  climate:  the  dynamic  characteristics  of  buildings  that  comply  with  the  environmental  control  management (eqm) technology are as follows.   use  of  an  adaptive  comfort  approach  in  the  indoor  environment  and  improved  comfort  measures [ ]   use of heat pump technology for simultaneous heating and cooling   integration of heating, cooling and ventilation within the building fabric   integrated control systems to operate and optimize the hvac operation    for eqm details look [  to  ] and for neural networks in [  to  ]  thus, a development that started about   years ago with integrated design process, is now  formulated as a strong technological package that can lead the fourth scientific revolution. with the  path now evident, we propose adding new expertise to the idp team, namely a building automatic  control (bac) expert.    author contributions: mtb building science, ar‐z automatics, dwy writing text  funding: this research received no external funding  conflicts of interest: the authors declare no conflict of interest    references  . 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, amalfi, italy. wos:   . dudzik, marek, mielnik, ryszard, wrobel, zofia, preliminary analysis of the effectiveness of the use of  artificial neural networks for modelling time‐voltage and time‐current signals of the combination wave    generator. in proceedings of the   international symposium on power electronics, electrical drives,  automation and motion (speedam),  –  june  , amalfi, italy. wos:       ©   by the authors. licensee mdpi, basel, switzerland. this article is an open access  article distributed under the terms and conditions of the creative commons attribution  (cc by) license (http://creativecommons.org/licenses/by/ . /).    gaba actions and ionic plasticity in epilepsy gaba actions and ionic plasticity in epilepsy kai kaila , , eva ruusuvuori , , patricia seja , , juha voipio and martin puskarjov , available online at www.sciencedirect.com sciencedirect concepts of epilepsy, based on a simple change in neuronal excitation/inhibition balance, have subsided in face of recent insights into the large diversity and context-dependence of signaling mechanisms at the molecular, cellular and neuronal network level. gabaergic transmission exerts both seizure- suppressing and seizure-promoting actions. these two roles are prone to short-term and long-term alterations, evident both during epileptogenesis and during individual epileptiform events. the driving force of gabaergic currents is controlled by ion- regulatory molecules such as the neuronal k-cl cotransporter kcc and cytosolic carbonic anhydrases. accumulating evidence suggests that neuronal ion regulation is highly plastic, thereby contributing to the multiple roles ascribed to gabaergic signaling during epileptogenesis and epilepsy. addresses department of biosciences, university of helsinki, fi- helsinki, finland neuroscience center, university of helsinki, fi- helsinki, finland corresponding author: kaila, kai (kai.kaila@helsinki.fi) current opinion in neurobiology , : – this review comes from a themed issue on inhibition: synapses, neurons and circuits edited by gordon fishell and gábor tamás for a complete overview see the issue and the editorial available online th november - # the authors. published by elsevier ltd. http://dx.doi.org/ . /j.conb. . . much of the neurobiological research on epilepsies has focused on the role of gabaergic transmission in various phases of disease progression. alterations in gabaergic signaling, which include changes in the properties of interneurons and in their quantitative as well as qualita- tive postsynaptic effects, are intimately involved in the development and chronic manifestations of epileptiform activity. in this review, we focus on gabaa receptor (gabaar) functions and the ion transporters which affect the reversal potential of gabaar-mediated cur- rents (egaba). ‘ionic plasticity’ [ ] (figure ) refers to changes in neuronal signaling related to the operation and functional modulation of plasmalemmal ion transporters open access under cc by license. current opinion in neurobiology , : – (figure a) which set egaba either directly (cl � and/or hco � transporters) or indirectly (the na-k atpase). epilepsies have turned out to be a spectrum disorder with a range of etiologies and comorbidities. concepts of epilepsy and epileptogenesis seem likely to undergo revisions [ , � ]. here we will mainly focus on mesial temporal lobe epilepsy (tle) which is the most common type of refractory epilepsy. the primary cause leading to tle is typically an insult to the brain (traumatic brain injury, inflammation, status epilepticus), but in patients the nature of the initial insult remains often unknown because of long delays between the insult and appearance of the recurrent seizures characteristic of tle [ ]. seizures in the non-epileptic brain seizures can take place in disease states other than epi- lepsy. refractory status epilepticus (se), a life-threatening epileptic crisis characterized by prolonged recurrent sei- zures which do not respond to diazepines [ ], is caused by factors such as inflammation and stroke, and it is seen in a minority of patients with established epilepsy. much of our knowledge on the mechanisms and consequences of sei- zures come from in vivo and in vitro work on animals with no previous history of epilepsy or epileptogenesis. induc- tion of experimental se has been shown to produce fast and robust changes in neuronal plasticity and a fast de- velopment of pharmacoresistance to conventional antiepi- leptic drugs which enhance gabaergic transmission. a straightforward explanation (see [ , ]) is that recurrent seizures lead to a progressive internalization of postsyn- aptic gabaars and to a consequent erosion of inhibition. work on brain slices has shown that the efficacy of feedfor- ward inhibition declines rapidly after recurrent seizure-like activity, leading to a loss of the powerful inhibitory sur- round that is initially associated with these paroxysmal events [ , � , ]. seizures evoked in healthy adult brain tissue induce a fast decrease in the expression of kcc [ – ], the main neuronal cl � extruder. this molecule underlies classical, ‘eccles-type’ hyperpolarizing inhibi- tory postsynaptic potentials (ipsps) in central neurons [ ]. gabaergic inhibition also has a shunting effect on electrical signals in the postsynaptic membrane (box ). the downregulation of gabaars and kcc in response to trauma and/or intense seizure activity (figure b) leads to a long-lasting decrease in the efficacy of both shunting and voltage inhibition, respectively. the extrusion capacity of kcc can saturate even in the absence of functional downregulation [ � ] of the trans- porter. therefore, the loss of voltage inhibition in response to www.sciencedirect.com kai.kaila@helsinki.fi http://www.sciencedirect.com/science/journal/ / http://dx.doi.org/ . /j.conb. . . http://dx.doi.org/ . /j.conb. . . http://www.sciencedirect.com/science/journal/ http://creativecommons.org/licenses/by/ . / gaba actions and ionic plasticity in epilepsy kaila et al. figure ion channels generate currents by dissipating these gradients dfi gi ii = gi × dfi ion transporters generate electro- chemical gradients that set the dfs for distinct ionic species cl- loading through activation of gabaars post-translational downregulation of kcc genomic downregulation of kcc seconds minutes hours days weeks ionic plasticity of gabaa receptor signaling neuronal/synaptic plasticity has traditionally been associated with modulation of the functional expression and properties of channels (ionic conductances, gi). current opinion in neurobiology ionic plasticity of gabaa receptor signaling refers to modulation of neuronal functions via changes in the driving force dfgaba = vm − egaba via short- and long-term mechanisms: ( ) activity-evoked, channel-mediated changes in cl- and hco - gradients which control egaba ( ) changes in the functionality (trafficking, kinetics, and synthesis/degradation) of ion-regulatory molecules such as cation-chloride cotransporters (kcc , nkcc ), the na-k atpase and carbonic anhydrases an important property of gabaa receptor-mediated signaling is the uniquely high sensitivity of egaba and, consequently df gaba to activity-induced cl- fluxes and to changes in the efficacy of kcc - mediated cl- extrusion. the diagram below depicts the time domains of neuronal cl--loading mechanisms following seizure activity. ionic plasticity of gabaa receptor signaling. seizure activity is likely to be much faster than the loss of shunting. this is because the intense activation of inter- neurons will lead to a massive cl � influx which is aided by the depolarizing currents mediated by hco � across gabaars and by coactivation of glutamatergic ionotropic receptors [ ], as shown by continuous monitoring of egaba [ ]. in fact, the depolarization mediated by the hco � current can drive a cl � influx that is large enough to induce a qualitative change in gabaar-mediated signaling from inhibitory to excitatory [ , � ]. during intense gabaar activation, the driving force of the inward hco � current is much more stable than that of the outward cl � current because the intracellular hco � is effectively replenished by neuronal cytosolic carbonic anhydrase [ , � ]. indeed, under experimental conditions with enhanced synaptic release of gaba, pharmacologi- cally isolated gabaar-mediated transmission alone is able to produce spontaneous paroxysmal activity in the brain slice [ ]. the effect of the hco � -dependent anion shift is augmented by kcc -mediated net accumulation of k + in the interstitial space [ � ], leading to further, non- synaptic depolarization and excitation of neurons. this www.sciencedirect.com probably includes (the at its time enigmatic observation of) gaba-driven antidromic spiking [ ]. the membrane potential of glial cells is highly sensitive to extracellular k + , and the above positive feedback loop may act in synergy with glutamate release [ ] from depolarized glia [ ] to sustain a seizure. gabaars and the na-k- cl cotransporter nkcc (but not kcc ) are expressed in presynaptic terminals [ ], and thus the antidromic spiking might also involve a direct presynaptic gabaar depolar- ization following an activity-dependent anion shift within the terminal. the role of extracellular k + is a classical focus in epilepsy research [ ], and the time is ripe to readdress this topic with the novel insight pointing to gabaergic k + transients as a major pro-convulsant mechanism [ , ]. seizures in the epileptic brain it is likely that seizure mechanisms in chronically epileptic tissue differ dramatically from those evoked in brain tissue in healthy experimental animals or observed in patients with no previous history of epilepsy. even if no cognitive defects are detectable during seizure-free periods of time, the cortex of chronically epileptic patients generates current opinion in neurobiology , : – inhibition: synapses, neurons and circuits figure (a) (b) na+ k + cl - k+ na + k+ cl - na+ k+ cl - nkcc ae hco - cl- accumulating cl- cl- cl- cl- cl- h o + co h+ + hco - na+ hco - k+ cl- k+ k+ cl- k+ cl- postsynaptic hyperpolarization by cl- influx postsynaptic depolarization by cl- effluxhealthy trauma atp cl- extruding hco - ca /ca kcc nkcc nkcc kcc kcc atp na+ na + ndcbe gaba gaba gaba current opinion in neurobiology neuronal ion regulation sets the driving force for gabaa receptor-mediated currents. (a) the cation chloride cotransporters govern neuronal cl � regulation. in mature neurons the k-cl cotransporter isoform , kcc , mediates cl� extrusion driven by the k+ gradient while the na-k- cl cotransporter isoform , nkcc , mediates na+ driven cl� uptake. in addition to this, the na+-independent and na+-dependent cl-hco exchangers ae and ndcbe, respectively, may modulate intracellular cl� levels. the main function of these hco � transporters, together with the ubiquitous na- h exchanger (not depicted), is to keep the intracellular ph level significantly more alkaline than what is predicted on the basis of passive distribution of h+ and hco � ions. hence, the equilibrium potential for hco � is much more positive than the resting membrane potential and hco � invariably mediates a depolarizing current across gabaars. intracellular hco � concentration is rapidly replenished even during prolonged gabaar activation via the activity of carbonic anhydrase isoforms and (ca and ca ) which catalyze the formation of hco � from co [ �]. (b) the cation-chloride cotransporters shown in panel (a) are fueled by the na+ and k+ gradients generated by the na-k atpase. the conventional, gabaar-mediated hyperpolarizing ipsps seen in mature neurons depend on the functional expression of kcc (left) that maintains a low intracellular cl� level that favors conductive cl� influx. seizure-induced post-translational changes in ccc functional expression, e.g. via altered membrane expression, commence in tens of minutes. prolonged changes at the levels of post-translational modification and transcription convert gabaar signaling back to its immature, depolarizing/excitatory mode of action during the course of epileptogenesis (right). the positive shift in egaba assists in reducing energy consumption during ‘energy crisis’ by reducing the driving forces of temporally overlapping and mutually counteracting excitatory and inhibitory postsynaptic ion fluxes (see [ ]). for further details, see text. abnormal interictal activities which are seen as brief (tens of milliseconds) spikes in the eeg. in hippocampal tissue from tle patients, the in vitro counterpart of interictal activity is highly sensitive to bumetanide [ ], a drug that selectively blocks cl � uptake mediated by nkcc in neurons in vitro [ ]. in a manner similar to the depolarizing gabaar actions and associated nkcc -dependent net- work events in the immature rodent hippocampus [ ], interictal activity in vitro shows an obligatory dependence on excitatory gabaergic and glutamatergic excitatory synaptic drive [ , �� ]. in hippocampal tissue resected from human tle patients, intracellular recordings have revealed a subpopulation of pyramidal neurons where kcc levels are low and gaba has an excitatory action current opinion in neurobiology , : – [ , ] (see also [ ]). thus, gabaar signaling appears to resume its immature, depolarizing/excitatory mode of action at least in some pyramidal neurons during the course of epileptogenesis. however, while the changes in cation- chloride cotransporter (ccc) expression levels (low kcc , high nkcc ) in these cells provide an explanation for the generation of interictal activity, there are no data to suggest that ictogenesis is based on these mechanisms (for review see [ ]). intriguingly, it seems to be more difficult to evoke seizures in human tle tissue than in brain tissue from healthy animals [ � ]. this is a difficult paradox, since surgically obtained human tle tissue typically has a www.sciencedirect.com gaba actions and ionic plasticity in epilepsy kaila et al. box synaptic and extrasynaptic gabaar signaling synaptic gabaar-mediated inhibition is based on shunting and hyperpolarization of the postsynaptic membrane. shunting inhibi- tion has a duration set by the gabaar channels’ open time, and the associated increase in conductance acts to suppress the temporal and spatial summation of incoming excitatory synaptic signals, as well as intrinsic pro-excitatory currents generated in the dendritic tree. voltage inhibition, which hyperpolarizes the postsynaptic membrane, is dependent on the inwardly-directed electrochemical gradient of cl�, maintained by kcc , and it counteracts excitatory mechanisms for a longer time period, which is set by the time constant of the cell membrane. unlike shunting, voltage inhibition does not take place in all types of mature cns neurons because of cell-type specific lack of kcc . the postsynaptic gabaars in the neocortex and hippocampus consist of a( - ), b(x) and g subunits [ ] whereof the of a b g is the most common one. tonic gabaar-mediated signaling is based on the activation of high-affinity extrasynaptic gabaars (with a subunit combination consisting of a bg , a bd or a bd in neocortical and hippocampal neurons) by ambient gaba. the subunit composition of gabaars undergoes marked changes during epileptogenesis with consequent changes in the abundance of postsynaptic and extrasynaptic receptors [ ], often followed by an increase in tonic inhibition [ ]. tonic gabaergic signaling is highly sensitive to changes in the efficacy of gaba uptake transporters (gat - ) [ ], and it produces a spatially extended shunting effect in the target neurons, with voltage changes set by dfgaba. excessive tonic inhibition is known to promote absence seizures by inducing slow-wave discharges in thalamo-cortical networks, while enhancing tonic inhibition has an anticonvulsant action in partial seizures and catamenial epilepsy [ ]. synaptic gabaergic signaling is often called ‘phasic’ (e.g. ‘phasic inhibition’) to underscore its distinct properties versus tonic signal- ing. both phasic and tonic gabaar-mediated signaling can be functionally inhibitory or excitatory, depending on the ion-regulatory mechanisms which set egaba and dfgaba; on the gabaar-mediated conductance; and on the intrinsic electrophysiological properties of the target neuron. sclerotic ca region, and such macroscopic differences in the properties of the healthy versus chronically diseased circuitry will compromise evaluation of the effects of distinct cccs or changes in their expression. in slices from human tle tissue, seizure-like events are not preceded by interictal but rather by ‘pre-ictal’ events which are largely based on recurrent glutamatergic sig- naling [ �� , ]. these bursts have a wide spatial extent and a high propagation speed which probably makes them particularly effective in activating interneurons [ � ]. while dendritic gabaergic synapses are lost in animal models of chronic epilepsy [ ], a wealth of data suggest that parvalbumin-positive, perisomatically targeting interneurons shape the rhythmicity and synchrony which makes it possible for the seizures to effectively spread across wide cortical territories [ ]. what triggers seizures in tle? the diversity of recent explanations shows that this fundamental problem has still not been satisfactorily solved. we note that the term ‘trigger’ is ambiguous in that it has been used to describe (i) extrinsic factors that increase the propensity of seizures (e.g. hyperventilation or fever in children) and (ii) the www.sciencedirect.com intrinsic neuronal and network mechanisms that act as immediate causes for seizure generation. here, we will consider the latter. there is evidence that local desyn- chronization of neuronal activity is needed for the initiation of seizure activity [ ]. thus, a simple working hypothesis for the generation of tle-related seizures and the role of kcc therein might be constructed as follows: in the seizure-triggering ‘kernel’ of diseased tissue, pre-ictal activity leads to a loss of phasic hyper- polarizing ipsps (box ), which results (over short times) from the high cl � load [ , ] and is enhanced and consolidated largely by post-translational downregulation of membrane-associated kcc [ � , � ] and later (cf. [ � ]) by block of kcc transcription (figure ). the lack of hyperpolarizing ipsps will lead, in turn, to the local desynchronization and promotion of seizures [ ]. this idea is consistent with and supported by the actions of hyperpolarizing inhibition on spike probability and timing in healthy tissue [ ]. trkb and calpain as coordinating factors in epileptogenesis and epilepsy bdnf-trkb signaling has been put forward as a coordi- nating factor in epileptogenesis [ – ]. indeed, the parallel loss of postsynaptic gabaars and kcc after recurrent seizures may imply a shared mechanism, which most likely consists of signaling cascades down-stream of the tropomyosin-related kinase b (trkb) receptor [ ], the main target of brain-derived neurotrophic factor (bdnf). seizures enhance bdnf secretion and the activation of trkb [ ] but, notably, bdnf itself is not always responsible for seizure-induced trkb acti- vation (cf. [ ]). conditional knockout of trkb [ ], transient inhibition of trkb [ ] or uncoupling of trkb from the plcg cascade [ � ] are all reported to suppress epileptogenesis. enhanced trkb activation in mature neurons rapidly decreases surface expression of gabaars [ , ] and downregulates kcc [ , ]. there exist close parallels between the role of bdnf- trkb signaling in epilepsy and in chronic pain [ ]. in both cases, inflammation may induce bdnf secretion from activated microglia, and cause a downregulation of kcc in adjacent neurons [ ]. notably, inflammation is also a major cause of se and epileptogenesis [ ]. fast, seizure-induced downregulation of kcc activity (over tens of minutes to hours), depends on post- transcriptional mechanisms [ � , � ], including protein phosphatase -mediated dephosphorylation of kcc at serine [ � , ] and cleavage by the protease calpain [ � , ], which is activated by ca + and/or bdnf (for review, see [ ]). a decrease in kcc mrna occurs within hours of a seizure [ ] and may contribute to consolidate kcc downregulation (figure ), but is not needed for chronic suppression of kcc protein expression or cl � extrusion [ ]. indeed, the increased level of calpain expression observed in tle tissue [ , ] could account current opinion in neurobiology , : – inhibition: synapses, neurons and circuits for the chronic suppression of hippocampal kcc expres- sion observed in patients with chronic epilepsy (see above). interestingly, up-regulation of the gene encoding for the endogenous calpain inhibitor calpastatin is observed during the acute and latent phase of limbic epileptogen- esis, whereas this enhancement appears to be lost in the chronic phase, characterized with spontaneous recurrent seizures [ ]. notably, calpain cleaves not only kcc [ � , , ] but also other proteins involved in gabaergic transmission, including gad [ ], vgat/viiat [ ], gat [ ] and gephyrin [ ]. thus, mounting evidence suggests that activation of calpain is another coordinating factor in epileptogenesis with important effects on gaba- ergic signaling (see also [ ]). developmental stage and seizure mechanisms neuronal signaling mechanisms are radically different in developing and mature brain. one of the best examples is gabaar-mediated signaling, which undergoes a well- known ‘developmental shift’ from depolarizing/excit- atory to hyperpolarizing (for review, see [ , ]). initially neuronal cl � accumulation by nkcc is dominant, and kcc is expressed later during neuronal maturation [ ]. the maturation of kcc -dependent hyperpolarizing inhibition is accompanied by the expression of neuronal carbonic anhydrase isoform (ca ), at around postnatal day (p) in rodent hippocampus [ ], followed by neuronal expression of the ubiquitous ca isoform (ca ) at �p [ �]. the simultaneous presence of kcc and ca activity is crucial both for the generation of gaba-dependent neuronal cl � loads in response to interneuronal activity, and for paroxysmal extracellular k + transients [ � ]. the key role of nkcc in immature, depolarizing gabaergic transmission and gaba-driven network events has led to a number of studies in neonatal rodents on the possible therapeutic use of the nkcc blocker, bumetanide. this work has been largely disap- pointing, as described elsewhere [ ]. cortical develop- ment is much more advanced in the human newborn than in the rodent [ ]. unlike in neonate rodents, ca and kcc are both expressed at high levels in hippocampus and neocortex of full term human babies [ � , � , , ]. this major species difference has numerous implications for translational work on the mechanisms of gabaergic signaling and seizures. adaptive mechanisms from an evolutionary point of view, it is easy to under- stand why neurons and neuronal networks are endowed with adaptive response patterns which promote their survival under various insults [ ]. adaptive mechanisms can be detected, for instance, in the slowing of disease progression induced by application of proconvulsant drugs such as atipamezole and rimonabant soon after an insult [ , ]. moreover, whether disease stage- related expression patterns of the endogenous calpain current opinion in neurobiology , : – inhibitor calpastatin [ ] (see above) are causally involved here, is an interesting question for future work. clearly, empirical information is required to judge whether a disease-related change at the molecular, cel- lular or network level is a ‘dysfunction’ (maladaptive, pro-epileptogenic) or an adaptive (anti-epileptogenic) process. after trauma, neurons undergo processes of de-differen- tiation, seen as a shift in gene expression patterns to those of earlier developmental stages [ , ]. the adaptive value of such processes may be best explained from the factors involved in neuronal survival after trauma: (i) downregulation of energy metabolism under con- ditions of an ‘energy crisis’ (see [ ]); as well as the presence of (ii) sufficient connectivity and (iii) trophic factor signaling, which promote neuronal survival. with regard to (i), the mammalian brain works close to theor- etical limits on energy consumption, with most of it used to maintain the ionic driving forces which are needed for electrical signaling [ , ]. changes in the functions and expression patterns of ion transporters and channels may thus have evolved as adaptive mechanisms to protect neurons during states of energy crisis. this idea fits well with the fast downregulation of both ion transporters and channels (e.g. gabaars and kcc ) in response to seizures (see above and figure b). furthermore, the na-k atpase, the major ion-regulatory and energy-con- suming molecule of the brain, is functionally downregu- lated after trauma or seizure [ , ]. the na-k atpase and kcc are functionally tightly linked, and there is evidence that the two molecules form a structural ion- transport metabolon [ , ]. we note also that shutting down cl � permeable gabaars will reduce the energy- metabolic load imposed by cation-based glutamatergic signaling [ ]. conclusions changes in excitation–inhibition (e/i) balance are often used to explain epileptogenesis and seizure generation but, as should be obvious from the work reviewed above, the explanatory value of the e/i balance in the context of epilepsy is limited. moreover, the postulated cause (e/i imbalance) is deduced from the outcome (seizures), which is an obvious circular argument. a gross change in the e/i imbalance is not, either, consistent with the fact that seizures in chronic epilepsy can occur infrequently and unpredictably, with intervening periods of intact cognitive and mnemonic cortico-hippocampal functions. the studies reviewed presently demonstrate that gabaar signaling has multiple, context-specific and age-specific actions which can prevent or promote epi- leptogenesis and seizure generation. a context-specificity and age-specificity is true also for intracellular signaling cascades such as those down-stream of trkb receptors [ – ], which exert a strong influence on neuronal plasticity. this context-dependent diversity in cellular www.sciencedirect.com gaba actions and ionic plasticity in epilepsy kaila et al. and molecular signaling is not only a major challenge for basic research on the etiology and mechanisms of epi- leptiform syndromes, but also for the design of novel, genuinely antiepileptic drugs [ ] which, instead of hav- ing solely symptomatic anticonvulsant actions, would halt and even reverse the progression of epilepsy. acknowledgements we thank profs. wolfgang löscher and richard miles for constructive comments on an early version of this paper. the authors’ original work was supported by the academy of finland, the sigrid jusélius foundation, the jane and aatos erkko foundation and the letten foundation. references and recommended reading papers of particular interest, published within the period of review, have been highlighted as: � of special interest �� of 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. . löscher w, klitgaard h, twyman re, schmidt d: new avenues for anti-epileptic drug discovery and development. nat rev drug discov , : - . . hines rm, davies pa, moss sj, maguire j: functional regulation of gabaa receptors in nervous system pathologies. curr opin neurobiol , : - . . grabenstatter hl, russek sj, brooks-kayal ar: molecular pathways controlling inhibitory receptor expression. epilepsia , (suppl. ): - . . pavlov i, walker mc: tonic gaba(a) receptor-mediated signalling in temporal lobe epilepsy. neuropharmacology , : - . . madsen kk, white hs, schousboe a: neuronal and non- neuronal gaba transporters as targets for antiepileptic drugs. pharmacol ther , : - . . brickley sg, mody i: extrasynaptic gaba(a) receptors: their function in the cns and implications for disease. neuron , : - . current opinion in neurobiology , : – http://dx.doi.org/ . / http://dx.doi.org/ . / 	gaba actions and ionic plasticity in epilepsy 	seizures in the non-epileptic brain 	seizures in the epileptic brain 	trkb and calpain as coordinating factors in epileptogenesis and epilepsy 	developmental stage and seizure mechanisms 	adaptive mechanisms 	conclusions 	acknowledgements 	references and recommended reading wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - 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: : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ untitled- © nature publishing group sweden's nuclear power game from wendy barnaby sweden's nuclear future has been de- cided-officiailly until . the ruling social democrats' ene,rgy plan, put to parliament last week and expected to be approved, provides for the construc- tion of nine reactors. with the four already in ope ration, sweden will have thi,iteen reactors wi,th a total electrical generating capacity of about , mw by . this will be only two more than previously ·planned, but the in- crease is seen by critics as the thin end whose wedge will be an existing gov- ernment plan to build reactors by . construction on ,that scale would make ,the swedes the world's greatest per capita users of nuclear power. the plan is a pi-ece of po\i.tics worthy of prime minister olof palme's con- siderable skills. forced last yea,r by pub- lic conce•m over the nuclea,r programme to postpone a decision on those plants not then under construction, he has with the present proposal g,iven the ap- pearance of ·responsible caution while allowing his government a reconsidera- tion in of the ways energy ,is to be provided for - . by , he explained, the,re would be more know- ledge available on which to make a better-informed decision. by , he could have added, the next parliamen- tary election will be safely out of the way with the emotional energy issue securely pegged for future considera- tion . on the face of it, nuclear power seems an obvious choice for sweden . although the country has no cheap uranium resources (.that is, uranium which can be mined for less than $ a pound), it has almost half the non- communist world's known suppues of uranium in the next price range-$ - a pound . it has been estimated that the supplies of cheap uranium may be- come sca,rce in the mid- s, partly because of the eight-year ,time lapse between discovery and production of deposits. unless exploration is stepped up, therefore, the more expensive uranium could come into demand at about ,the same time as ,the swedes' suspended nuclear programme would have been-and perhaps will still be- well advanced. sweden would expect to be a major exporter of reactoc fuel elements. but the nuclear issue has caused an extraordinarily vigorous pub- lic debate over ithe past year, focused mainly on the safety aspects and the disposa,l of nuclea,r waste . (in fact swe- den neatly solves its radioactive waste problems by sending its reactor fuel elements to windscale, england, for reproce,ssing.) more recently the social and security consequences of a nuclear decision have come in.to focus. pro- nuclear groups have insisted that no rise in the standa,rd of living will be possible without large scale nuclear powe,r, and have pointed out the dan- gers of dependence on foreign energy sources. anti-nuc-lea,r forces have res- ponded that the choice is not between increased growth and alternative energy sources: both are possible. the two new reactors proposed by the government are officially justified on ,the grounds that they, togeithe,r with increased hydroelectric power, will make up the extra billion kwh of electricity necessary for a projected in- crease of % a yea,r in energy con- sumption. non-oil-fired power stations are being emphasised in an attempt to lessen the country's dependence on the middle east. as the average annual in- crease in consumption over the years until was . % , the new projec- tion wi.ji ce,rtainly test the efficacy of save-energy campaigns. h is hoped that, hy , growth in energy consumption wih be zero. as well as changing the relative em- phasis on present energy sources, the plan provides money for research into fusion, geothermal, wind and solar power. but ,the fact ,that the allocations for this research are roughly only % of those for the huildi,ng of new reac- tors shows where the government's con- fidence lies . it will be surprising if, having laid the groundwork so skilfully, the social democrats do not use the review to hasten the day when the swedes will be the la,rgest users uf nuclear energy in the world. d oecd energy the organisation for economic co- operation and development (oecd) report on the problems and perspectives of energy research and development published ea,rlier this year provides a comprehensive and relatively up to date (se,ptember ) review of expendi- ture on all facets of energy research throughout the oecd countries, which include europe, the united states. canada, australia, new zealand and japan. although the report does not commit itself to specific criticisms of member states' energy research programmes, it obviouslv feels the need for a longer term approach to the problem, which aopears to be lacking in many aspects of energy research programmes set un in resnonse to the 'energy crisis' of j. it warns for instance that the sudden unsurne in enerp.:v r&d must not he subiected to cutbacks once the most soectacular effects of the crisis have receded and the nrohlcm has become less sensitive politically. in general the distribution of re- sources should be directed to keeping nature vol. march as many alternative sources of energy open as possible . research aimed at energy production should no jonget be limited to one primary source . perhaps the country which has made the largest turnaround is the united states which now supports a massive and diverse programme on every conceivable aspect of energy production but which pre- viously had based its energy policy very largely on the availability of cheap imported oit one important and as yet relatively undeveloped field of energy research is energy systems. this covers the inter- relationships between production, trans- port and use of energy and also takes in any factors which might have a bear- ing on the smooth functioning of that system, such as effects on the environ- ment and supply of skilled manpower. the use of energy accounting to clarify the energy flow through these systems from the level of primary energy up to the finished product is also encouraged. the study of energy systems, says oecd, can be an extremely important factor in moulding future policies. although the tables of statistics and resea·rch programmes are necessarily incomplete and sometimes countries cannot be directly compared as some figures include a measure of industrial research whereas some pertain to gov- ernment expenditure only, they provide interesting reading. the usa of course leads the field spending over $ , million in the fiscal year . france and germany spent around $ mil- lion and $ million respectively and the united kingdom spent around $ million in - . with regard to the organisation of energy policy, the oecd picks out britain and the united states as the only two countries which have set up a new ministry or agency to deal with the complete problem, thus fixing a p~li~y course that links energy r&d admm s- tration with general energy policies. in other countries, energy research has been taken under the wing of the science ministries, where they exist, or handed to some ad hoc committee. where energy problems can be re- duced to matters of technology to be solved by a specific research pro- gramme, the outlook seems fairly optimistic. the member states of oecd comprising as they do the most highly developed indust,rialis~d societi~s , are orientated to cope relatively easily with that type of problem . but energy is an extremely delicate political sub- ject and affects the whole nature of society. therefore, says oecd, "future development [of energy] will mainly depend on the political decisions of countries with regard to the nature _of their economic growth and social structures". d 	sweden's nuclear power game energy conference econstor make your publications visible. a service of zbw leibniz-informationszentrum wirtschaft leibniz information centre for economics hamburg institute of international economics (hwwa) (ed.) article — digitized version energy conference: fruitiess talks intereconomics suggested citation: hamburg institute of international economics (hwwa) (ed.) ( ) : energy conference: fruitiess talks, intereconomics, issn - , verlag weltarchiv, hamburg, vol. , iss. , pp. , http://dx.doi.org/ . /bf this version is available at: http://hdl.handle.net/ / standard-nutzungsbedingungen: die dokumente auf econstor dürfen zu eigenen wissenschaftlichen zwecken und zum privatgebrauch gespeichert und kopiert werden. sie dürfen die dokumente nicht für öffentliche oder kommerzielle zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. sofern die verfasser die dokumente unter open-content-lizenzen (insbesondere cc-lizenzen) zur verfügung gestellt haben sollten, gelten abweichend von diesen nutzungsbedingungen die in der dort genannten lizenz gewährten nutzungsrechte. terms of use: documents in econstor may be saved and copied for your personal and scholarly purposes. you are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public. if the documents have been made available under an open content licence (especially creative commons licences), you may exercise further usage rights as specified in the indicated licence. www.econstor.eu comments energy conference fruitless talks a f t e r nine days of negotiations the paris prelim- inary conference, convened to fix the number of participants to, the place, and the agenda of the planned energy summit between oil producing, oil consuming, and developing countries, ended without result in mid-april. right from the start there was a confrontation between two diametri- cally opposed basic opinions. the industrialised countries held the view that the negotiations should be confined to energy problems and re- lated issues and warned of one of those mam- moth jamborees with endless disputes and meagre results. contrary to this the mineral oil producing and the developing countries were not willing to content themselves with an oil con- ference but insisted in putting all raw materials as well as questions of development aid on the agenda. that the failure of the conference did not evoke much distress in the industrialised countries did not come as a surprise since the energy crisis seems to have lost much of its urgency: there is plenty of oil available, the oil producers' cartel has shown first indications of a break-up, and the recycling of the petro-dollars has so far refuted the gloomy predictions of a financial drying-up of the industrial nations. this, however, means also a deterioration of the other raw material pro- ducers' chances to obtain, with the support of the oil countries, a new price system for their own products and to establish a new world eco- nomic order according to the principles passed by the majority of delegates to the un general assembly. notwithstanding their present, rela- tively strong, position the industrialised countries would, however, be ill-advised to leave it at that until further notice. the energy situation could soon change again and in the long run they will in any case have to concede a larger share of the world's wealth to the raw material producing countries, ch. raw materials a i e c - a n e w cartel? eleven states meeting in geneva have decided to form an association of iron ore exporting countries (aiec) with headquarters in london. the initiators, on the one hand, stressed that their organisation was not to operate as a cartel but, on the other hand, the association shall help above all to bring about better trading conditions and higher export prices. australia, india, peru, sierra leone, sweden and venezuela are among the aiec's members. the ussr, the usa, canada and the p.r. china - ac- counting together for more than half the world's iron ore production of mn tons in - are staying outside. whether brazil, one of the major exporting countries, will join an "ore cartel" is very much in doubt: its government aims at doub- ling production and expanding exports; a clash of interests would be inevitable if the "ore club" felt tempted to hold up prices by tightening supplies. in view of the fact that the most important pro- ducers and some of the major exporting countries as well are so far standing apart from the aiec, it does not look probable that an opec-like iron ore cartel will come into being. aiec is more likely to remain a consultative body without in- cisive powers. the conference chairman, the indian minister chattopadhyaya, said that the association would demonstrate the ability of the exporting states to defend their "legitimate" inter- ests without violating the interests of the con- sumers. but conflicts will probably be avoided only as long as one side accepts as "legitimate" what the other side deems to be "legitimate". iwe. taiwan the death of the generalissimo chiang kai-shek, the man whom sun yat-sen, the father of modern china, saw as his successor, is dead. little had been heard of him since the u-turn in us policy to china. it was as long ago as that the then young officer came into contact with the nationalist and social reformer sun yat-sen, and when sun and his national people's party, the kuomintang, in suc- ceeded in forming a government, chiang was a member of it. by that time the kuomintang had developed into a movement set to rally the whole nation. amongst others it included the communist party of china which had been founded in . after sun yat-sen's death chiang soon emerged as the leader of the kuomintang. he surrounded himself at first with many leftist advisers, amongst them chou en-lai who became his chief of staff. in however chiang unexpectedly broke with the communists. the kuomintang government was made up of politicians of moderate views. in the decades which have elapsed since, the duel between chiang and mao has dominated the po- litical scene inside china and engaged the in- terest of the world. often it seemed that chiang was close to final victory, but later the fortunes of war turned forever: chiang with two millions intereconomics, no. , rotenone-induced energy stress decompensated in ventral mesocerebrum is associated with parkinsonism progression in rats. | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /etm. . corpus id: rotenone-induced energy stress decompensated in ventral mesocerebrum is associated with parkinsonism progression in rats. @article{bai rotenoneinducedes, title={rotenone-induced energy stress decompensated in ventral mesocerebrum is associated with parkinsonism progression in rats.}, author={qunhua bai and junlin he and yong tang and s. wang and jing-fu qiu and yang wang and c. yu}, journal={experimental and therapeutic medicine}, year={ }, volume={ }, pages={ - } } 	qunhua bai, junlin he, + authors c. yu 	published 	biology, medicine 	experimental and therapeutic medicine parkinson's disease (pd) is the second most common neurodegenerative disorder, which is characterized by the hallmark feature of loss of dopaminergic neurons in the substantia nigra. energy metabolic disorder is associated with the pathogenesis of pd; however, the development of this disorder is yet to be elucidated. pd-like characteristics have been demonstrated in a rotenone rat model. in the present study, energy metabolism status was investigated in a rat model following intraperitoneal… expand view on pubmed spandidos-publications.com save to library create alert cite launch research feed share this paper citations view all figures and topics from this paper 	 figure 	 figure 	 figure 	 figure 	 figure view all figures & tables 	rotenone 	parkinsonian disorders 	lactic acid 	parkinson disease 	neurodegenerative disorders 	adenosine triphosphate 	metabolic diseases 	substantia nigra structure 	dopamine hydrochloride 	dopaminergic neurons 	nadh 	tyrosine -monooxygenase 	lactate dehydrogenase citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency docosahexaenoic acid protection in a rotenone induced parkinson's model: prevention of tubulin and synaptophysin loss, but no association with mitochondrial function 	norma serrano-garcía, f. fernández-valverde, e. luis-garcía, l. granados-rojas, a. jiménez-anguiano 	chemistry, medicine 	neurochemistry international 	 	 save alert research feed bougainvillea spectabilis flowers extract protects against the rotenone-induced toxicity. 	o. abdel-salam, e. youness, + authors d. abouelfadl 	biology, medicine 	asian pacific journal of tropical medicine 	 	 	 save alert research feed proteomic changes driven by urban pollution suggest particulate matter as a deregulator of energy metabolism, mitochondrial activity, and oxidative pathways in the rat brain. 	j. e. araujo, s. jorge, + authors j. l. capelo 	chemistry, medicine 	the science of the total environment 	 	 save alert research feed references showing - of references sort byrelevance most influenced papers recency a highly reproducible rotenone model of parkinson's disease 	j. cannon, víctor tapias, h. na, anthony s. honick, j. t. greenamyre 	biology, medicine 	neurobiology of disease 	 	 	 save alert research feed chronic rotenone exposure reproduces parkinson's disease gastrointestinal neuropathology 	r. drolet, j. cannon, l. montero, j. t. greenamyre 	biology, medicine 	neurobiology of disease 	 	 save alert research feed rotenone, deguelin, their metabolites, and the rat model of parkinson's disease. 	p. caboni, t. sherer, + authors j. casida 	chemistry, medicine 	chemical research in toxicology 	 	 save alert research feed rotenone induces non‐specific central nervous system and systemic toxicity 	nicolas lapointe, m. st-hilaire, + authors f. cicchetti 	biology, medicine 	faseb journal : official publication of the federation of american societies for experimental biology 	 	 save alert research feed lessons from the rotenone model of parkinson's disease. 	j. t. greenamyre, j. cannon, r. drolet, pier-giorgio mastroberardino 	biology, medicine 	trends in pharmacological sciences 	 	 	 save alert research feed stress‐induced neurological impairments in an animal model of parkinsonism 	a. snyder, e. stricker, m. zigmond 	psychology, medicine 	annals of neurology 	 	 save alert research feed dysregulation of glucose metabolism is an early event in sporadic parkinson's disease☆ 	l. dunn, g. allen, + authors r. bandopadhyay 	biology, medicine 	neurobiology of aging 	 	 	pdf save alert research feed mitochondria in the aetiology and pathogenesis of parkinson's disease. 	a. schapira 	biology, medicine 	the lancet. neurology 	 	 save alert research feed rotenone model of parkinson disease 	a. panov, s. dikalov, natalia shalbuyeva, g. taylor, t. sherer, j. t. greenamyre 	biology, medicine 	journal of biological chemistry 	 	 	pdf save alert research feed delayed gastric emptying and enteric nervous system dysfunction in the rotenone model of parkinson's disease 	j. g. greene, a. noorian, s. srinivasan 	medicine 	experimental neurology 	 	 	 save alert research feed ... ... related papers 	abstract 	figures and topics 	 citations 	 references 	related papers stay connected with semantic scholar sign up about semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue news and views from synthetic genome to creation of life xiaoxue zhang understanding the world and then changing the world is an everlasting mission of the human being. life is an important component and one of the most sophisticated elements on the earth. in recent decades, the rapid development of molecular biology, genetics and the related biotechnology and bioengineering kept bringing surprises to scientists worldwide, including the cloning of dolly (wilmut et al., ) (followed by cloning of a variety of animals), the completion of human genome project (cheung et al., ; lander et al., ; venter et al., ) (followed by the reports of complete genome from other species and by the spread of personalized genome sequencing service), and the induction of pluripotent stem cells (takahashi and yamanaka, ) (followed by the production of viable ips mice (zhao et al., )). recently, another breakthrough was brought by john craig venter and his team, who achieved the first synthetic life—mycoplasma that only contains synthetic genome (gibson et al., ). now, “synthetic biology” has become a keyword for life science area to describe the design and construction of new biological parts, devices, and systems, and the re-design of existing, natural biological systems for useful purposes (http:// syntheticbiology.org/). despite the deciphered genetic code and expanding information about genetics and epigenetics, synthesizing life from chemical components is still limited by scientific knowledge and technical practicability. john craig venter is a leading scientist in genomic research. with the invaluable contribution of celera genomics that he funded in , the human genome project was completed three years ahead of expected date. later, he funded j. craig venter institute (jcvi), with synthetic genomics as one of the major focuses. after years of investigation and approximately $ million of investment, jcvi walked out this significant step for synthetic biology. the synthetic genome started with design of dna sequence, which highly depends on the accurate sequence of mycoplasma mycoides genome. venter group spent numerous efforts on comparing different sequencing results, making necessary corrections, and setting watermark sequences to differentiate synthetic and natural genomes. the whole . -mbp genome was divided into dna cassettes, each containing bp, with bp overlap to adjacent cassettes, and they were individually synthesized by chemical approach. ten cassettes were recombined in yeast to yield the -kb intermediates, which were further recom- bined to obtain the -kb intermediates and the final complete genome. the correct assembly was confirmed by both multiplex pcr and restriction analysis, and the synthetic m. mycoide genomes were transplanted into restriction-minus mycoplasma capricolum recipient cells. bacteria with syn- thetic genomes were screened by tetracycline and x-gal as designed, and were also verified by multiplex pcr, restriction analysis, whole genome sequencing (the sequenced strain was referred as m. mycoides jcvi-syn . ), etc. under the experimental condition, the cells with only synthetic genome were able to perform self-replication and logarithmic growth. proteomics analysis revealed that these cells have nearly identical protein expression pattern as the genome donor, m. mycoide, but not the recipient, m. capricolum. shortly after the announcement of this result, the scanning and transmission electron micrograph of synthetic m. mycoide has become a most popular image around the world. this “artificial” life is a hallmark on both conceptual and technical aspects. dna is supposed to contain all the genetic information for life. it is a complicated process to obtain accurate whole genome sequence and to synthesize an error-free genome with rounds of manipulation before final transplantation. such work requires high-throughput sequen- cing facilities, innumerous data processing, sophisticated designing strategy, precise chemical synthesis, multiple steps of quality control, etc. the success of synthetic m. mycoides reveals the power of current biotechnology to accomplish such a marvelous project. in addition, it proves the principle of producing cells from computer-designed genome rather than modifying dna sequence by traditional insertion, deletion or mutagenesis. at current moment, the m. mycoides with synthetic genome is almost identical to the naturally existing m. mycoides; it opens the door for scientists to make synthetic cells with distinguished, predicted and/or even unnatural properties. although ethical concerns have emerged, such as its potential application on bioterrorism, the technique will have significant implications in pharmaceutical field, © higher education press and springer-verlag berlin heidelberg protein cell , ( ): – doi . /s - - - protein & cell environmental science, clean energy, food industry, etc. in spite that the synthetic m. mycoides is called “synthetic cell” and its dna bases are solely synthesized by chemical approach, the process still relies highly on life components. first, the synthetic dna fragments, including the -bp dna cassettes, -kb intermediates and -kb intermedi- ates, were assembled in yeast cells, in which these pieces were recombined together to finally form a complete functional genome. the pathway and regulation of such recombination in yeast is not well understood. whether the assembly can be finished in a life-free or a synthetic microenvironment remains to be explored. second, the synthetic genome required an existing cell, m. capricolum, to provide cytoplasm, which contains a variety of life components that could be potentially essential for the function of synthetic genome. compared to synthesizing dna, it may be more difficult to reproduce such a complicated cellular environment with all required cellular organs, inorganic elements, organic matters and life macromolecules, such as proteins, carbohydrates and lipids, and the membrane. they play indispensable roles in dna packaging, transcription, translation, protein expression as well as other cellular functions. therefore, a synthetic genome itself may not fully represent an “artificial” life; however, this is a significant advancement because it is the genome that contains all inheritable genetic information. despite the involved life components, the extensive labor and financial investment, and the safety concerns, this “synthetic” bacterium is undoubtedly a milestone for synthetic biology. m. mycoides has the smallest genome in free-living organisms. it may take a long way to fully realize the dream of creating life, but it can be expected that in the near future, the synthetic procedure will be optimized and the cost will be reduced, which will bring benefits to everyday life and the challenges human beings face, e.g., energy crisis, environ- mental pollution, and increased co . references cheung, v.g., nowak, n., jang, w., kirsch, i.r., zhao, s., chen, x. n., furey, t.s., kim, u.j., kuo, w.l., olivier, m., et al. ( ). integration of cytogenetic landmarks into the draft sequence of the human genome. nature , – . gibson, d.g., glass, j.i., lartigue, c., noskov, v.n., chuang, r.y., algire, m.a., benders, g.a., montague, m.g., ma, l., moodie, m. m., et al. ( ) creation of a bacterial cell controlled by a chemically synthesized genome. science (in press). lander, e.s., linton, l.m., birren, b., nusbaum, c., zody, m.c., baldwin, j., devon, k., dewar, k., doyle, m., fitzhugh, w., et al. ( ). initial sequencing and analysis of the human genome. nature , – . takahashi, k., and yamanaka, s. ( ). induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors. cell , – . venter, j.c., adams, m.d., myers, e.w., li, p.w., mural, r.j., sutton, g.g., smith, h.o., yandell, m., evans, c.a., holt, r.a., et al. ( ). the sequence of the human genome. science , – . wilmut, i., schnieke, a.e., mcwhir, j., kind, a.j., and campbell, k.h. ( ). viable offspring derived from fetal and adult mammalian cells. nature , – . zhao, x.y., li, w., lv, z., liu, l., tong, m., hai, t., hao, j., guo, c.l., ma, q.w., wang, l., et al. ( ). ips cells produce viable mice through tetraploid complementation. nature , – . © higher education press and springer-verlag berlin heidelberg xiaoxue zhangprotein & cell 	outline placeholder 	bmkcit 	bmkcit 	bmkcit 	bmkcit 	bmkcit 	bmkcit 	bmkcit acupuncture in medicine: sage journals skip to main content intended for healthcare professionals cookies notification this site uses cookies. by continuing to browse the site you are agreeing to our use of cookies. find out more. cart menu 	 search 	 browse 	 resources 	 authors 	 librarians 	 editors 	 societies 	 advanced search in this journal 	 journal home 	 browse journal 	current issue 	onlinefirst 	accepted manuscripts 	all issues 	free sample 	 journal info 	journal description 	aims and scope 	editorial board 	submission guidelines 	abstracting/indexing 	reprints 	journal permissions 	subscribe 	recommend to library 	advertising & promotion 	 stay connected 	email alerts 	rss feed 	feedback / contact sage 	 submit paper advanced search 	 search 	 browse 	 resources 	 authors 	 librarians 	 editors 	 societies 	 advanced search view cart sign in carnegie mellon univ library society access options you can be signed in via any or all of the methods shown below at the same time. my profile sign in here to access free tools such as favourites and alerts, or to access personal subscriptions 	 the email address and/or password entered does not match our records, please check and try again. email (required):* password (required):* remember me forgotten your password? i don't have a profile create profile i am signed in as: view my account logout with my free profile i can: 	set up favourite journals and register for email alerts 	list saved searches 	edit account details 	activate personal subscriptions and access content institution if you have access to journal content via a university, library or employer, sign in here shibboleth open athens research off-campus without worrying about access issues. find out about lean library here i am signed in via: carnegie mellon univ library research off-campus without worrying about access issues. find out about lean library here with institutional access i can: 	view or download all content the institution has subscribed to. society if you have access to journal via a society or associations, read the instructions below members of _ can log in with their society credentials below 	username (required)	 	password (required)	 	society (required)	 the int society for research on emotion american college of veterinary pathologists 	 login failed. please check you selected the correct society from the list and entered the user name and password you use to log in to your society website. access to society journal content varies across our titles. if you have access to a journal via a society or association membership, please browse to your society journal, select an article to view, and follow the instructions in this box. contact us if you experience any difficulty logging in. some society journals require you to create a personal profile, then activate your society account activate my society account i am signed in via: institution logout with society access i can: 	view or download all the content the society has access to. need help? contact sage need help? contact sage cart search all journals search this journal advanced search acupuncture in medicine . impact factor journal indexing & metrics » 	 journal home 	 browse journal 	current issue 	onlinefirst 	accepted manuscripts 	all issues 	free sample 	 journal info 	journal description 	aims and scope 	editorial board 	submission guidelines 	abstracting/indexing 	reprints 	journal permissions 	subscribe 	recommend to library 	advertising & promotion 	 stay connected 	email alerts 	rss feed 	feedback / contact sage 	 submit paper search 	 previous slide < 	 about this journal acupuncture in medicine aims to promote the scientific understanding of acupuncture and related treatments by publishing scientific investigations of their effectiveness and modes of action as well as articles on their use in health services and clinical practice. acupuncture in medicine uses the western understanding of neurophysiology and anatomy to interpret the effects of acupuncture. more 	 next slide > all issues current issue onlinefirst 	 latest articles 	 most read 	 most cited 	 trending on altmetric articles most recently published online for this journal. 	 after trim spaces title : effects of acupuncture versus cognitive behavioral therapy on brain-derived neurotrophic factor in cancer survivors with insomnia: an exploratory analysis effects of acupuncture versus cognitive behavioral therapy on brain-derived neurotrophic factor... kevin t liou, sheila n garland, q susan li, keimya sadeghi, jamie green, isidora autuori, irene orlow, jun j mao 	 mar - onlinefirst first published: mar 	 	 after trim spaces title : control intervention matters: an important but often ignored factor affecting clinical heterogeneity in meta-analyses of acupuncture trials control intervention matters: an important but often ignored factor affecting clinical heteroge... tae-hun kim, jung won kang 	 mar - onlinefirst first published: mar 	 	 after trim spaces title : electroacupuncture therapy for acute gastrointestinal injury: review and perspectives electroacupuncture therapy for acute gastrointestinal injury: review and perspectives xiaotong chen, mengdie wu, jing li 	 mar - onlinefirst first published: mar 	 	 after trim spaces title : electroacupuncture stimulation at bl , bl and sp prevents hind limb unloading–induced osteoporosis in rats electroacupuncture stimulation at bl , bl and sp prevents hind limb unloading–induce... honghui wang, desheng wang, zhili li, shujuan liu, jingjing dong, jianfeng zhang, huijuan wang, minjie wang, bo ji, yinghui li 	 mar - onlinefirst first published: mar 	 	 after trim spaces title : electroacupuncture inhibits il- /il- r and post-receptor mapk signaling pathways in a rat model of chronic obstructive pulmonary disease electroacupuncture inhibits il- /il- r and post-receptor mapk signaling pathways in a rat mod... xin-fang zhang, shui-ying xiang, jing lu, yin li, shu-jun zhao, chuan-wei jiang, xiang-guo liu, zi-bing liu, jie zhang 	 mar - onlinefirst first published: mar 	 	 after trim spaces title : chemokine cxcl in serum mediates the antinociceptive effect of manual acupuncture at st chemokine cxcl in serum mediates the antinociceptive effect of manual acupuncture at st shou-hai hong, sha-sha ding, yuan xu, kuo zhang, xue zhao, yang-yang liu, li-hua xuan, yong-ming guo, yi guo 	 mar - onlinefirst first published: mar 	 	 after trim spaces title : additional value of auricular intradermal acupuncture alongside selective serotonin reuptake inhibitors: a single-blinded, randomized, sham-controlled preliminary clinical study additional value of auricular intradermal acupuncture alongside selective serotonin reuptake in... hong wang, xiao-ru liu, xiao-jing wu, ti-zhen he, dan miao, jin-feng jiang, hui-fen qiao, wing-fai yeung, zhi-ling sun 	 mar - onlinefirst first published: mar 	 	 after trim spaces title : treatment of headache disorders with acupuncture: a -year retrospective study treatment of headache disorders with acupuncture: a -year retrospective study javier mata, pilar sanchís, pedro valentí, beatriz hernández, jose luis aguilar 	 feb - onlinefirst first published: feb 	 	 after trim spaces title : intraoral acupuncture treatment for obstructive sleep apnoea with snoring: a case series intraoral acupuncture treatment for obstructive sleep apnoea with snoring: a case series jungeun ko, jungeui baik, suji lee, sanghoon lee 	 feb - onlinefirst first published: feb 	 view more view less view all onlinefirst articles > view current issue > most read articles in this journal in the last months. 	 after trim spaces title : improvement in inflammation and airway remodelling after acupuncture at bl and st in a mouse model of chronic asthma improvement in inflammation and airway remodelling after acupuncture at bl and st in a mous... ida nurwati, bambang purwanto, ambar mudigdo, koosnadi saputra, diding heri prasetyo, muthmainah muthmainah 	 aug - vol , issue first published: jun views: citations: 	 	 after trim spaces title : the effectiveness and safety of acupuncture for patients with atopic eczema: a systematic review and meta-analysis the effectiveness and safety of acupuncture for patients with atopic eczema: a systematic revie... ruimin jiao, zhongyang yang, yang wang, jing zhou, yuxiao zeng, zhishun liu 	 feb - vol , issue first published: sep views: citations: 	 	 after trim spaces title : evidence of efficacy of acupuncture in the management of low back pain: a systematic review and meta-analysis of randomised placebo- or sham-controlled trials evidence of efficacy of acupuncture in the management of low back pain: a systematic review and... yan xiang, jin-yuan he, huan-huan tian, bing-yan cao, rui li 	 feb - vol , issue first published: sep views: citations: 	 	 after trim spaces title : acupuncture for the treatment of lower limb diabetic peripheral neuropathy: a systematic review acupuncture for the treatment of lower limb diabetic peripheral neuropathy: a systematic review jane nash, mike armour, stefania penkala 	 feb - vol , issue first published: mar views: citations: 	 	 after trim spaces title : acupuncture in sham device controlled trials may not be as effective as acupuncture in the real world: a preliminary network meta-analysis of studies of acupuncture for hot flashes in menopausal women acupuncture in sham device controlled trials may not be as effective as acupuncture in the real... tae-hun kim, myeong soo lee, terje alraek, stephen birch 	 feb - vol , issue first published: sep views: citations: 	 	 after trim spaces title : effects of electroacupuncture on anxiety and depression in unmarried patients with polycystic ovarian syndrome: secondary analysis of a pilot randomised controlled trial effects of electroacupuncture on anxiety and depression in unmarried patients with polycystic o... zhi wang, haoxu dong, qing wang, lina zhang, xiaoke wu, zhongming zhou, li yang, dongmei huang 	 feb - vol , issue first published: mar views: citations: 	 	 after trim spaces title : transcutaneous electrical acupuncture point stimulation improves pregnancy outcomes in patients with recurrent implantation failure undergoing in vitro fertilisation and embryo transfer: a prospective, randomised trial transcutaneous electrical acupuncture point stimulation improves pregnancy outcomes in patients... zhenhong shuai, xuemei li, xuelian tang, fang lian, zhengao sun 	 feb - vol , issue first published: mar views: citations: 	 	 after trim spaces title : effects of manual acupuncture combined with donepezil in a mouse model of alzheimer’s disease effects of manual acupuncture combined with donepezil in a mouse model of alzheimer’s disease jing jiang, gang liu, suhua shi, yujie li, zhigang li 	 feb - vol , issue first published: mar views: citations: 	 	 after trim spaces title : effects of acupuncture on breast cancer-related lymphoedema: a systematic review and meta-analysis of randomised controlled trials effects of acupuncture on breast cancer-related lymphoedema: a systematic review and meta-analy... xinyan zhang, xiuli wang, bingyan zhang, sa yang, dongling liu 	 feb - vol , issue first published: mar views: citations: 	 view more view less view all onlinefirst articles > view current issue > view more most read articles > most cited articles published in this journal in the last years. these statistics are updated weekly using data sourced exclusively from crossref. 	 after trim spaces title : acupuncture for lumbar disc herniation: a systematic review and meta-analysis acupuncture for lumbar disc herniation: a systematic review and meta-analysis shujie tang, zhuomao mo, renwen zhang 	 apr - vol , issue first published: apr citations: views: 	 	 after trim spaces title : effects of dry needling on post-stroke spasticity, motor function and stability limits: a randomised clinical trial effects of dry needling on post-stroke spasticity, motor function and stability limits: a rando... zacarías sánchez-mila, jaime salom-moreno, césar fernández-de-las-peñas 	 dec - vol , issue first published: dec citations: views: 	 	 after trim spaces title : effectiveness of acupuncture in postpartum depression: a systematic review and meta-analysis effectiveness of acupuncture in postpartum depression: a systematic review and meta-analysis shanshan li, weiqiang zhong, wen peng, gaofeng jiang 	 oct - vol , issue first published: oct citations: views: 	 	 after trim spaces title : the impact of stricta and consort on reporting of randomised control trials of acupuncture: a systematic methodological evaluation the impact of stricta and consort on reporting of randomised control trials of acupuncture: a s... simen svenkerud, hugh macpherson 	 dec - vol , issue first published: dec citations: views: 	 	 after trim spaces title : warm needle acupuncture in primary osteoporosis management: a systematic review and meta-analysis warm needle acupuncture in primary osteoporosis management: a systematic review and meta-analysis ding luo, yue liu, yanan wu, rui ma, lin wang, ronghe gu, wenbin fu 	 aug - vol , issue first published: dec citations: views: 	 	 after trim spaces title : clinical effects and safety of electroacupuncture for the treatment of post-stroke depression: a systematic review and meta-analysis of randomised controlled trials clinical effects and safety of electroacupuncture for the treatment of post-stroke depression: ... xue-bin li, jie wang, an-ding xu, jian-min huang, lan-qing meng, rui-ya huang, jing xu 	 oct - vol , issue first published: oct citations: views: 	 	 after trim spaces title : effect of acupuncture on the tlr / -nf-κb signalling pathway in a rat model of traumatic brain injury effect of acupuncture on the tlr / -nf-κb signalling pathway in a rat model of traumatic ... shu-jun lin, lu-xi cao, shao-bing cheng, qiu-fu dai, ji-huan lin, liu pu, wei-hao chen, yu-juan zhang, shu-lian chen, yi-min zhan and more... 	 aug - vol , issue first published: aug citations: views: 	 	 after trim spaces title : regulation of the il- /st pathway contributes to the anti-inflammatory effect of acupuncture in the ovalbumin-induced murine asthma model regulation of the il- /st pathway contributes to the anti-inflammatory effect of acupuncture ... ming dong, cheng ma, wen-qian wang, juan chen, ying wei 	 oct - vol , issue first published: oct citations: views: 	 	 after trim spaces title : effects of scalp electroacupuncture on the pi k/akt signalling pathway and apoptosis of hippocampal neurons in a rat model of cerebral palsy effects of scalp electroacupuncture on the pi k/akt signalling pathway and apoptosis of hippoca... hanhong zhang, jing gao, mengmeng wang, xuefeng yu, xiuhua lv, huan deng, xiangwei fan, kaiyun chen 	 apr - vol , issue first published: apr citations: views: 	 view more view less view all onlinefirst articles > view current issue > view more most cited articles > articles with the highest altmetric score from the last months, indicating influence and impact. loading ... tell us what you think we're continually looking for ways to enhance the site to make sure you're having the best experience. we greatly value your feedback! feedback editorial team editor   	 david coggin-carr university of vermont, usa, and university college london, uk associate editors 	 mike cummings, bmas, uk 	 simon hayhoe, essex county hospital, uk 	 adrian white, university of plymouth, uk   view all publish with us authors will enjoy: 	 rigorous peer review of your research 	 prompt publishing 	 multidisciplinary audience 	 high visibility for global exposure submit now more from this journal connect with us email alerts sign up and receive alerts: 	 with the latest table of contents 	 when new articles are published online sign up add email alerts close add email alerts dialog you are adding the following journals to your email alerts 	 journal	 new content 	 announcements 	acupuncture in medicine	 	 related journals 	 molecular pain 	 cephalalgia 	 clinical rehabilitation 	 british journal of pain 	 journal of evidence-based complementary & alternative medicine 	 journal of holistic nursing 	 integrative cancer therapies 	 journal of feline medicine and surgery view more view fewer also from sage publishing 	 cq library american political resources opens in new tab 	 data planet a universe of data opens in new tab 	 lean library increase the visibility of your library opens in new tab 	 sage business cases real-world cases at your fingertips opens in new tab 	 sage campus online skills and methods courses opens in new tab 	 sage knowledge the ultimate social science library opens in new tab 	 sage research methods the ultimate methods library opens in new tab 	 sage video streaming video collections opens in new tab sage journals about privacy policy terms of use contact us help accessibility browse health sciences life sciences materials science & engineering social sciences & humanities journals a-z discipline hubs resources authors editors reviewers librarians researchers societies opportunities advertising reprints content sponsorships permissions microsites acupuncture in medicine issn: - online issn: - copyright © by british medical acupuncture society cookies notification this site uses cookies. by continuing to browse the site you are agreeing to our use of cookies. find out more. bioenergy plants in indonesia: sorghum for producing bioethanol as an alternative energy substitute of fossil fuels energy procedia ( ) – - © the authors. published by elsevier ltd. selection and peer-review under responsibility of the scientifi c committee of indonesia ebtke conex doi: . /j.egypro. . . sciencedirect conference and exhibition indonesia renewable energy & energy conservation [indonesia ebtke conex ] bioenergy plants in indonesia: sorghum for producing bioethanol as an alternative energy substitute of fossil fuels rahayu suryaningsiha,*, irhasa adepartment of physics engineering, faculty of engineering,gadjah mada university, jl. grafika no. , yogyakarta , indonesia abstract indonesia's energy demand is increasing every year. bioenergy plants are expected to be one of the solutions to fill energy demand in indonesia. sorghum is a bioenergy plant that can be used in indonesia for producing bioethanol. sorghum bioethanol is produced from sorghum biomass waste processing results with fermentation process. ethanol is derived from fermented sorghum which is about - %. sorghum bioethanol can be used as an alternative fuel that is renewable and can be used as a substitute for fossil fuels. © the authors.published by elsevier ltd. selection and peer-review under responsibility of the scientific committee of indonesia ebtke conex . keywords: bioenergy plants; renewable energy; sorghum; bioethanol; biomass waste; fermentation process . introduction currently, the world is started to lack of energy sources from fossil fuels. therefore, it is necessary to attempt to find alternative sources of renewable energy [ ]. in indonesia, the issue of energy crisis also crowded discussed in recent years. energy crisis occurred due to start depletion of fossil fuel reserves. because of excessive human consumption and dependence on fossil fuels is causing fuel reserves become depleted, while the time required for its renewal thousands and even millions of years. vegetable-based fuels are expected to reduce the shortage of fuel, so *corresponding author. tel: + - . e-mail address:rahay @gmail.com available online at www.sciencedirect.com © the authors. published by elsevier ltd. selection and peer-review under responsibility of the scientific committee of indonesia ebtke conex rahayu suryaningsih and irhas / energy procedia ( ) – the fuel needs will be met. vegetable-based fuels can also reduce environmental pollution, making it more environmentally friendly [ ]. as cereals plants (grains), sorghum has a multiuse benefits. in addition, the seeds used as food, stems and leaves for fodder, the sugar contained in the seeds (carbohydrate) or liquid / juice / sap stem (sweet sorghum) can be processed into ethanol (bioethanol). sap is made from sorghum can used for bioethanol industry has developed in many countries such as usa, china, india and belgium. nowadays, the productivity of sorghum bioethanol in the united states totaled litters/ha, india - litters/ha and china litters/ha. as biofuels, sorghum bioethanol used in various purposes, such as blended with gasoline (premium) for motor vehicles or better known as gasohol. in india, beside gasohol, ethanol sorghum is also used as a fuel for lighting lamps (pressurized ethanol lantern) called "noorie" which produces - lumens (about equivalent to a w light bulb). sorghum bioethanol is also used as a cooking stove fuels (ethanol pressurized stove) that produce heat capacity of kw [ ]. this paper explained about the process of making sorghum bioethanol and the advantages of it to fill the energy requirement in indonesia. . material and method the method which is used for write this paper by literature review about: . . renewable energy in indonesia. renewable energy is developed and used in indonesia. it is caused by the energy decrease which is made from fossil fuel, so that we look for another energy which can fuel cell energy demand. there are many kind of renewable energy which can be used in indonesia like wind energy, solar cell, wave energy and bioenergy. bioenergy is one of the potential energy which is made from bioenergy plant. some bioenergy plants in indonesia are red alga, sugar cane and sorghum. . . sorghum plants. sorghum is one of bioenergy plant. it can produce bioethanol who use as a fuel. this bioethanol is produced by fermentation process . . the process of making bioethanol. material that used in the bioethanol production is seed sorghum which is milled (grinding) to get the starch [ ]. grain sorghum is crushed into flour sorghum with size mesh and the characteristic of grain sorghum is shown in table . table . the characteristic of sorghum grain [ ]. substance sorghum grain content (%) starch . - . protein . - . water . - . besides that, it is also used saccharomyces cerevisiae, nutrient (npk and urea) and some reagents for analysis. in general, the process of making bioethanol from sorghum can be seen in fig. . rahayu suryaningsih and irhas / energy procedia ( ) – fig. . process of making bioethanol from sorghum [ ]. in the process of producingsorghum bioethanol, there are some important factors to consider because it may influence the products of bioethanol. the factor which is influenced for the result of bioethanol production are the length of time is fermentation and scarification, the number of additional starter, fermentation temperature, sterilization equipment, and the success of the process of distillation. all these factors can be varied for bioethanol optimization. . result and discussion . . sorghum plants. in indonesia, sorghum has been recognized by farmers, especially in java, ntb, and ntt, but the cultivation and development is still very limited. sorghum is a potential crop to be cultivated and developed in indonesia, particularly in arid regions. the sorghum excellences are in resistance to drought, high production, production costs are relatively inexpensive and more resistant to pests and diseases compared with other crops. the sorghum plant is shown in fig. . fig. . sorghum plants [ ]. in terms of agronomy, crop sorghum growing requirements that do not require a spoiled, has a wide adaptability, low input crop, and more drought resistant sorghum or otherwise can live in stagnant water. in addition, sorghum can be planted with “ratun” systems that require less labor, because the plants can be harvested two to three times for planting only once [ ]. sorghum plant can be used for various things such as food sources, as a source of animal feed, as fuel energy from plants, and industrial raw materials. scarification process dextrin glucose fermentation process glucose bioethanol rahayu suryaningsih and irhas / energy procedia ( ) – . . bioethanol from sorghum plants . . . ethanol ethanol is a liquid which is widely used for various purposes based on its concentration. chemical properties of ethanol are not toxic, can be used as a solvent in the chemical and pharmaceutical industry, a mixture of gasoline, cosmetics and medicines. ethanol also has physical properties: molecular weight is . g / mole; density at ° c is . gr/cm ; boiling point is . ° c; specific gravity . at a temperature of °c. there are two methods used to produce ethanol, the hydration of ethylene and fermentation. however, due to an increase in crude oil prices, the production of ethanol made from raw materials containing starch such as cassava, sweet potatoes, corn, sorghum and corn. as well as materials that contains sugar and cellulose through a process of fermentation and distillation. in the anaerobic conditions, the yeast produces ethanol, based on gay-lussac equation: c h o c h oh + co + atp (energy released: kj per mole) ( ) based on the above fermentation reaction, one molecule of glucose in the fermentation will produce molecules of ethanol and carbon dioxide. based on weight gram glucose will theoretically produce . grams of ethanol. because most of the carbon source used for biomass formation, so that the actual ethanol yields ranged from - % of the theoretical. [ ] . . . the process of making sorghum bioethanol bioethanol is ethanol produced from biomass raw materials such as cassava, maize, potatoes, wheat, sugarcane, beet, and sorghum. bioethanol can be used as an alternative fuel that is renewable and is used as a substitute for fossil fuels [ ]. in indonesia, production of sorghum still dwarfs, the national average only about - tons per year which is expected to produce bioethanol - litters / ha / year. bioethanol from sorghum is also not used optimally by the society. sorghum juice contains glucose levels are quite large because of the quality of sweet sorghum juice is equivalent to sugar juice and not fully utilized to obtain the alcohol from sorghum juice with fermentation process. table . comparison of the composition of sorghum juice with sugar juice [ ]. composition sorghum juice sugar juice brix (%) . - . - sucrose (%) . - . - reduction sugar (%) . - . . - . total sugar (%) . - . - ami lum (ppm) - . - aconite acid(%) . . dust (%) . - . . - . sorghum is produced bioethanol by fermentation and distillation process. in general, the bioethanol production process includes five phases. the first stage is the process of grinding. the second stage is composed of a process pre fermentation include ph reduction process, the sterilization process, and the process of making a starter with add nutrients and saccharomyces cerevisiae. the third stage is the processes of fermentation for hours with add starter inoculum of the manufacturing process and add antifoam. the fourth stage is the distillation process. the fifth stage is sieve molecular dehydration [ ]. sorghum to ethanol conversion obtained cannot reach % (perfect), this is because not all the glucose can be converted into ethanol, but most of the glucose will be converted into co. the theoretical conversion of ethanol formation from glucose was % with the following reaction: rahayu suryaningsih and irhas / energy procedia ( ) – c h o c h oh + co with add the saccharomyces cerevisiae. ( ) conversion obtained under the conversion theory, this is because at the time of fermentation possibility of other microbial contamination. a bad sterilization is also resulted incomplete conversion [ ]. besides that, the conversion also depends on the length of the fermentation process, many starters are added, and the quality of sorghum juice is used. . . . the sorghum bioethanol optimization to obtain bioethanol with good quality, the optimization process should be done by modifying the factors that influence the result of the process of making bioethanol. based on several experiments that have been performed before, there are some values obtained in the optimization of sorghum bioethanol making process. the optimum point is the addition of % volume starter with . % ethanol content. fig. .the optimization of starter volume in % [ ]. the initial sugar concentration results the best sorghum starch liquefaction is . g / l at temperature °c. the best liquefaction temperature is at temperature ° c with ethanol concentration of g / l and time hours of fermentation [ ]. soaking using . % naoh solutions for longer soaking time increased the extractable protein content. with the increase of extractable protein content mean that the protein content in sorghum flour is decreased. table . extractable protein content [ ]. soaking with naoh hours hours extractable protein content (%) , , , , . . the advantages of sorghum bioethanol sorghum that has been processed into ethanol can be used as a substitute for kerosene fuel with ethanol content of - %, for laboratory and pharmacy needs - %, and a - % for premium materials [ ]. with this bioethanol is expected that fossil fuels can be substituted by using bioethanol from sorghum. replacement of fossil fuels with bioethanol can help to reduce the energy crisis that occurred in indonesia. in addition, bio-ethanol is also more environmentally friendly than fossil fuels so that,besides to reducing the energy crisis, bio-ethanol also helps to protect the environmental sustainability. rahayu suryaningsih and irhas / energy procedia ( ) – . conclusion sorghum is a bioenergy plants that can be developed in indonesia to produce bioethanol. ethanol is derived from fermented sorghum which is about - % depending on the quality of sorghum juice, fermentation and sterilization processes. bioethanol can be used as an alternative energy source in indonesia. acknowledgements acknowledgements will be gotten after this paper presentation and judgment in indonesia conex-ebtke . references [ ] jasman. productivity of biomass and sugar from sweet sorghum (sorghum bicolor (l) moench) as material bioethanol fermentation; . p. . [ ] assegaf, clevis f. banana (musa paradiacia) bioethanol production prospects using method of acid and enzymatic hydrolysis; . p. - [ ] humam, soeranto. sorghum as raw material of bioethanol. jakarta: batan national nuclear energy egency; . [ ] zuqni, meldha, chairul, said, amrani z. bioethanol production of sorghum stract wi scrafirication and fermentationn process with variation temperature liquefaction. pekanbaru: bioprocess engineering laboratory, chemical engineering departement, universitas riau; . p. . [ ] silvia. ethanol production from sorghum (sorghum bicolour l. moench) followed by enzymatic hydrolysis through fermentation using the saccharomices cerevisiae. s.l. biochemical technology laboratory; . [ ] ullman's. encylopedia of industrial chemistry. th ed. vol . weinheim: wileyvch verlag gmbh& co fgaa; . [ ] sani, sabrina n, azra y. bioethanol factory from sweet sorghum sap stem with fermentation process. surabaya: sepuluh nopember technology institute library; . [ ] directorate general of plantation indonesia. prospek pengembangan sorghum di indonesia. jakarta: directorate general of plantation indonesia; . [ ] sari rpp. manufacture of ethanol from sorgum sap stem with fermentation process. semarang. s.n.; . [ ] aqil m, marcia bp, muslimah h, balitsereal. sorghum for bioethanol production. vol. . sinar tani agroinovasi; . p. - . international journal of recent technology and engineering (ijrte) international journal of recent technology and engineering (ijrte) issn: - , volume- issue- , may published by: blue eyes intelligence engineering & sciences publication retrieval number: a / ©beiesp doi: . /ijrte.a .  abstract: this paper presents a device that uses the evolving iot technology to design and implement an internet-based energy meter. this meters, being cheap and easy-to-implement solution, enables consumers to monitor the daily usage of electric power easily. this work primarily concerns the energy-monitoring aspect of iot, along with discussing other advantages of this meter, such as its ability to overcome human errors and reducing dependency on manual labor, besides reducing costs in energy consumption. the proposed design in case ,and case which are comprises a low-cost wireless network for smart energy along with an android application capable of automatically reading the unit and then sending the data automatically provides great advantages to users by allowing them to keep a track of their meter reading. this system will help users by allowing them to not only take steps to reduce power wastage but also bring down costs of consumption, along with minimizing the threat of power theft, which is incurs great losses to power companies. experimental results of this study show that the proposed iot meter works efficiently and has proven its potential in practical applications at substantially reduced costs. keywords : sensing systems, smart energy meter, cost saving, data privacy, iot i. introduction electricity, which is the driving force behind the development of any country, is currently a global concern in the form of energy crisis. although an increase in energy production might seem like the answer to this problem, the actual remedy lies in the effective use of available energy. this might be made possible by a system that can effectively control and monitor power usage. one of the ideal approaches to addressing this current energy crisis is through reduced power usage at the household level. efficient energy monitoring is required for achieving this reduction in power usage. even in this digital age, consumers are not aware of their real-time energy consumption until the electricity bills are issued, and even in these technologically advanced times, labor-intensive work still continues. analogue energy meters, which were used decades back, are insensitive to minute power changes, and the values generated by them are not exactly accurate, leading to inaccurate reading and hence to the imprecise generation of bills. although digital watt meters, which revised manuscript received on may , . * correspondence author dakka. obulesu *, associate professor department of eee, cvr college of engineering, hyderabad, india.email: dakkaobulesh@gmail.com. k. s. v phani kumar, assistant professor department of eee, cvr college of engineering, hyderabad, india . email:phani @gmail.com rajab kumar kar, sr.assistant professor department of eee, cvr college of engineering, hyderabad, india.email: rajibkrkar@yahoo.co.in sample the voltage and current thousand times a second, have helped resolve these issues, an employee of the electricity board still has to make a monthly visit to each house to note down the power reading and to accordingly calculate the bill amount. to carry out this procedure, at least one member of the household should be present at home when the person arrives, which is bothersome for consumers because running errands or going about their personal and professional works get affected since one cannot predict the arrival of the electricity board personnel. moreover, an unknown person entering the house for power-reading purposes might also act like an invasion of one’s privacy. in india, electricity bills are generally issued either monthly or bimonthly. even in this digital era, consumers remain generally unaware about their energy consumption and do not take the pain to check the meter reading and compare it with the previous reading to obtain a fair idea about their consumption patterns. moreover, this entire procedure needs to be repeated several times a month to efficiently monitor and control energy usage, which becomes pretty cumbersome. however, if consumers were instead given the means to check their energy consumption using their mobile phones or laptops, it would not only become quick and efficient but also indicate a great advancement in the field of energy management. since most people are usually online almost * nowadays, allowing them to monitor their energy consumption online from anywhere will be quite helpful. ii. motivation and related work b. s. koay [ ] proposed a design of a bluetooth-enabled energy meter that can read energy meters wirelessly. two features were proposed, namely, the automatic meter reading (amr) and the automatic polling mechanism (apm), that will help retrieve the meter reading with little human intervention, and these were implemented in the targeted applications. the design is based on the csr bluetooth module as well as the analog device ade energy meter. brasek c. et al., [ ] proposed a new amr scheme using wifi technology and an arm-based pmwcm scheme. they suggested both economical and effective ways of implementing an amr system, which helped save costs in not just pre-building communication network but also in cable maintenance. this leads to sharing of broadband wireless network resources along with remote real-time management of the user's power data, helping save resource costs. design and implementation of cost-effective iot energy meter to monitor energy flow in smart grids dakka. obulesu, k. s. v phani kumar, rajab kumar kar mailto:rajibkrkar@yahoo.co.in design and implementation of cost-effective iot energy meter to monitor energy flow in smart grids published by: blue eyes intelligence engineering & sciences publication retrieval number: a / ©beiesp doi: . /ijrte.a . qiang fu et al., [ ] discussed microgrids, which are currently receiving quite some attention, due to the ever-increasing need to enable distributed generation, ensure power quality, and provide energy surety with regard to the critical load. hence, they analyzed a high renewable-energy penetrated micro-grid. qazi mamoon ashraf et al., [ ] implemented a prototype capable of acquiring energy-related data after a few seconds that allows the study of energy consumption patterns. the device was termed the elive device. the atmega microcontroller worked in harmony with an esp wifi system-on-chip (soc) module, an ac transformer, as well as current transducers. the esp allowed easy connection to the internet for the microprocessor with the use of an established wifi connection based on serial interfacing requirements. arduino integrated development environment (ide) was used to program the microcontroller that obtained energy measurements using an analog to digital converter (adc). li li, xiaoguan hu, jian huang, and rosario morello, [ - ] proposed a new scheme, which combines wifi and wimax with current various communication forms of amr, based on analyzing the differences of specific environments. this scheme, which aids the development of amr, provides a good solution and a meaningful exploration. dakka. obulesu , k. s. v. phani kumar et al [ ] proposed a wireless communication technology has made the exchange of information fast, secure and accurate. with the help of this technology, many of the industrial aspects of energy management can be automated, which will ultimately lead to the reduced usage of manpower. mismanagement of electrical energy is a prevalent problem in today's world. the only way to overcome this crippling drawback in electricity distribution is to develop an effective monitoring system. this paper proposes an integrated hardware and software solution that enables wireless monitoring of energy consumption to make it more convenient for the end user. this paper provides a way out of these above-mentioned difficulties caused by the previous mechanisms of measuring power.the proposed design considered in two cases, which comprises a low-cost wireless network and protocol for smart energy – along with a web application capable of automatically reading the unit and then sending the data automatically – provides great advantages to users by allowing them to keep a track of their meter reading. this system will help users by allowing them to not only take steps to reduce power wastage but also bring down costs of consumption, along with minimizing the threat of power theft, which has incurred great losses to power companies. the system has three components, namely, the digital energy meter, the esp wifi module, and web application. the esp wifi module is embedded into the meter, and the tcp/ip protocol is employed to allow seamless communication between the meter and the web application. iii. hardware design the block diagram of the hardware design of independent modules is represented in fig. . fig. . block diagram of the iot energy meter. the primary blocks of this hardware are the wifi module (esp ), the opto coupler (mct- e), the single-phase energy meter, an led, an ac to dc converter, a single-phase ac supply, regulated power supply, and load. the esp wifi module is a self-contained soc possessing an integrated tcp/ip protocol stack. the esp , which is a small wifi module built around the esp chip that can wirelessly connect a microcontroller to the internet, can provide any microcontroller access to a wifi network at minimal cost. the rapidly growing popularity of esp , launched in , can be proven from the fact that even though there is only one esp processor, it is found on many different breakout boards, which differ in terms of both which pins are exposed and in the size of the flash memory. over time, these breakout boards have also evolved rapidly, proving themselves ideal in this iot era. the esp – a low-cost wifi module that can be integrated easily into iot devices – features powerful on-board processing and storage capability that allows it to be integrated with the sensors and other application-specific devices by means of its general purpose input/output (gpio) with minimal upfront development and loading during runtime. its high degree of on-chip integration leads to its minimal external circuitry, including the front-end module, which is designed in such a way that it occupies a very small pcb area. the esp supports automatic power save delivery (apsd) for voice over ip (voip) applications along with bluetooth coexistence interfaces. its self-calibrated rf, which allows it to work under all operating conditions, makes it possible to mitigate the need for any external rf parts. international journal of recent technology and engineering (ijrte) issn: - , volume- issue- , may published by: blue eyes intelligence engineering & sciences publication retrieval number: a / ©beiesp doi: . /ijrte.a . the esp module – powered by a . v regulated power supply – has a maximum voltage input rating of . v, and thus voltages greater than . v would damage the module, making it important to be extremely cautions regarding the same. when connecting the esp to the power supply, the vcc and ground pins should be connected to the power supply lines and the power supply’s ground line needs to be connected to the arduino’s ground pin. because the arduino is powered via usb connection to the laptop, a common ground needs to be created for common reference to compare voltages and thereby interpret digital high and low signals. second, it is important to connect the output of a resistor voltage-divider circuit to the receive (rx) line for the esp module so as to transit the serial communication logic level (the highs and lows of the digital signals that make up the serial communications) from a logic high of volts on the arduino to a logic high of . v on the esp module. since the esp has a maximum voltage input rating of . v, connecting the module’s receive line directly to arduino’s transmit line might result in critical damage. however, since the module’s . v logic high is high enough to also register as a logic high on arduino, the esp ’s transmit line levels do not need shifting. after completing all the hardware connections, the program should be uploaded to arduino. the program will copy commands typed into the serial monitor and will send them to esp . the responses from the esp will be displayed in the serial monitor window. iv. results and discussions a. experimental results case-i this paper case –i present an overview of the wireless energy meter, which is very efficient for power measurement because inaccuracy is greatly reduced. the developed energy meter was tested using an electric light bulb of watts and a water heater of watts, driven by a supply voltage of v, which draws a current up to amperes as shown in fig. . the energy consumption was calculated, and the information was uploaded to the web page using it. the wifi helps transmit the energy consumption information to a web page. the energy consumption data are then sent to a web page by uploading the web server code. on a wifi esp serial monitor, the unit and cost of energy consumed are shown in fig. .consumers have the ease of obtaining energy consumption information just by filling in the login details online, anytime and anywhere, made possible by using wifi communication technology called iot. this information could be viewed by both consumers and utility. fig. shows the web information regarding unit and cost of electrical energy consumption. fig. output when supply is given fig. web information regarding unit and cost of electrical energy consumption b. experimental results case-ii in this case-ii the hardware considered for testing the system, shown in figure- consists of three energy meters (single phase pulses/kwh), assumed to be serving three households. each house is equipped with three loads. each energy meter is connected to a microcontroller (atmega p) with a wi-fi module (esp ) connected. there is a separate power supply (smps – v, a) for powering the microcontroller and the wi-fi module. a digital signal oscilloscope (dso) (tbs- b series) is used for capturing the signals going to the controller for analysis shown in figure- . for demonstration, load- in house- is switched on. now, energy meter starts measuring the energy consumed, and displayed as led blinks. since the circuitry and functioning of meter is not to be intruded, led blink samples are collected by means of an optocoupler and amplified. this information is sent to microcontroller and also connected to a dso for analysis. the sample measurement recorded is presented in figure - . the spikes in the graph correspond to the blinking of the led. since the load is constant, the spikes are placed equidistant to each other. the microcontroller also receives this information. design and implementation of cost-effective iot energy meter to monitor energy flow in smart grids published by: blue eyes intelligence engineering & sciences publication retrieval number: a / ©beiesp doi: . /ijrte.a . fig. : energy meters set up .” a counter is updated each time a spike event occurs. this counter value helps in evaluating what is the amount of energy consumed per hour or for an interval of time. the sample calculation can be shownas: i) if kw of load is switched on for hr, then total blinks = . ii) in one hour, if total blinks are , then the load connected is w. iii) in five min, if total blinks are , then the load connected is w. . fig – : led status when load- is switched on fig – : led status when load- is switched on fig – : led status when load- is switched on fig – : led status when the total load value is increased one day’s analysis is shown in the paper. load- is kept in on state for the entire day. the amount of energy consumed, and the cost incurred on the owner of the house is shown in figure and . load- is added in the house, at th hour. hence more energy is being consumed and the frequency of blinks starts to increase. this can be shown in figure – . keeping load and on, after six hours, load- is switched on. the sample led blinks are recorded in dso and shown in figure . and finally at th hour of the day, the capacity of the load is increased and hence the frequency of blinks increases, while the total energy consumption by the house also increases. in figure and it can be observed that the slope of the graph from hours to is less compared to that of slope of the graph from hours to , and so on. international journal of recent technology and engineering (ijrte) issn: - , volume- issue- , may published by: blue eyes intelligence engineering & sciences publication retrieval number: a / ©beiesp doi: . /ijrte.a . as the load is connected to the house, the counter value keeps increasing and hence, the user must pay an amount to the supplier of power proportionately based on the tariff. the tariff considered in this paper is . rs/kwh. fig – : counter value recorded by the microcontroller fig – : billing value estimated by the microcontroller v.conclusion this paper presented an overview of the smart energy meter for iot along with a low-cost implementation process, which is very efficient and accurate in energy measurement. the proposed energy meter set up in case : three energy meters (single phase pulses/kwh each), assumed to be serving three households can overcome challenges associated with the efficient management of energy. our developed meter allows one to read its parameters – load profile, demand value, and the total energy consumption – correctly and reliably. for iot implementation, the wifi module esp works reliably, which sends information to be displayed on the website throughout the existing server. this not only reduces human involvement, but also provides a capable meter reading and mitigates billing mistakes that can arise because of human intervention. the paper aims to propose a possible solution to the issues concerning the sensing and measurement aspects by discussing the potentialities of the proposed three energy meters.in case one single energy meter was also tested using electric appliances such as a light bulbs of watts, watts and watts are driven by a supply voltage of v. the energy consumption was calculated, after which the information was uploaded to the web page using iot. . references . b. s. koay, et al., “design and implementation of bluetooth energy meter”, proceedings of the joint conference of the fourth international conference on information., vol. , no. pp. - , december . . brasek. c et al., “urban utilities warm up to the idea of wireless automatic meter reading”, ieee computing & control engineering journal., vol. , no. pp. – , dec./jan. / . . qiang fu, luis f. montaya et al., “microgrids generation capacity design with renewable and energy storage addressing power quality and surety”,ieee transactions on smart grid., . . qazi mamoon ashraf and mohd izhan et al., “energy monitoring prototype for internet of things: preliminary results”, ieee nd world forum on internet of things (wf-iot), . . li li, xiaoguan hu and jian huang et al., “research on the architecture of automatic meter reading in next generation network”, th ieee international conference of industrail infermatics., july . . rosario morello, claudio de capua and gaetano fulco et al., “a smart power meter to monitor energy flow in smart grids: the role of advanced sensing and iot in the electric grid of the future,” ieee sensors j., vol. , no. , pp. , december , . . dakka. obulesu , k. s. v. phani kumar et al., “design and implementation of iot energy meter to monitor energy flow at the consumer end” asian journal of electrical sciences, vol. , no. , pp. - , . authors profile dr. d. obulesu received his b.e. degree in electrical and electronics engineering from stj institute of technology, karnataka university, karnataka, india, in and his m.tech in power electronics and drives from dr. m.g.r. university in . he received his phd degree in electrical engineering from jntu, hyderabad, india, in . he has teaching experience of nearly years. currently, he is working as associate professor in cvr college of engineering, telangana, india, in the department of electrical & electronics engineering. he has published a number of research papers in various national and international journals and conferences. his areas of interests are neural networks, fuzzy logic, artificial intelligence, power electronics, matlab, facts, and so on. phani kumar k.s.v received his b. tech degree in electrical and electronics engineering from anna university, chennai, india, in and his m.e from s.r.m university chennai, india, in . he is working as asst. professor in cvr college of engineering, telangana, india, in the department of electrical & electronics engineering, simultaneously doing his ph.d (research scholar) in electrical & electronics engineering from jntu, hyderabad. his area of interests is distributed generation, optimization techniques and power quality. rajib kumar kar received his b,tech degree in electrical and electronics from institute of engineers calcutta,india and m.tech degree in power system from punjab university, india in and respectively. at present he is working as senior assistant professor in cvr college of engineering. hyderabad. his area of research interest includes electrical measurements, power system operation and control. https://www.researchgate.net/journal/ - _ieee_transactions_on_smart_grid integrating bim with bms in energy performance assessment: case study of a university building in uk | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /ij dim. corpus id: integrating bim with bms in energy performance assessment: case study of a university building in uk @article{reginald integratingbw, title={integrating bim with bms in energy performance assessment: case study of a university building in uk}, author={ajiero ikenna reginald}, journal={int. j. d inf. model.}, year={ }, volume={ }, pages={ - } } 	ajiero ikenna reginald 	published 	engineering, computer science 	int. j. d inf. model. in recent times, energy performance assessment has gained a legislative imperative in that it constitutes an indispensable criterion for preparing energy performance certificates epcs. accordingly, production of epc which is heralded by energy audits and simulations using bim software programs heavily depends on data accuracy. whereas, there have been several studies on building information modelling bim and building management system bms autonomously, peer reviewed literature on both regimes… expand view via publisher igi-global.com save to library create alert cite launch research feed share this paper citations view all topics from this paper 	bim 	building information modeling 	battery management system 	electronic product code 	bridge management system 	simulation 	information model 	imperative programming 	gfa basic citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency investigating the effectiveness of bim-bms integration on managing existing building facilities: a new zealand educational building case 	tongrui zhang 	engineering 	 	view excerpt save alert research feed building information model for existing buildings for facilities management: retrobim framework 	g. carbonari, s. stravoravdis, christine gausden 	engineering, computer science 	int. j. d inf. model. 	 	 	pdf save alert research feed integration of bim work culture for improving global project collaboration productivity 	m. a. ghafar, r. ibrahim, zalina shari, f. rahimian 	computer science 	 	pdf save alert research feed managing uncertainty in geospatial predictive models 	iftikhar u. sikder 	computer science 	 save alert research feed references showing - of references sort byrelevance most influenced papers recency energy modeling system using building information modeling open standards 	h. kim, k. anderson 	computer science 	 	 save alert research feed building information modelling (bim) implementation and remote construction projects: issues, challenges and critiques 	yusuf arayici, c. egbu, paul coates 	engineering, computer science 	j. inf. technol. constr. 	 	 	pdf save alert research feed bim & the d project cost manager 	p. smith 	engineering 	 	 	pdf save alert research feed building information modelling for tertiary construction education in hong kong 	kam-din andy wong, k. f. wong, abid nadeem 	engineering, computer science 	j. inf. technol. constr. 	 	 	pdf save alert research feed model interoperability in building information modelling 	j. steel, r. drogemuller, b. toth 	computer science, engineering 	software & systems modeling 	 	 	pdf save alert research feed bim handbook: a guide to building information modeling for owners, managers, designers, engineers and contractors 	c. eastman, p. teicholz, r. sacks, k. liston 	engineering 	 	 , save alert research feed an integrated infrastructure for real-time building energy modeling and fault detection and diagnostics 	b. dong, zheng o'neill, + authors trevor bailey 	computer science 	 	 save alert research feed describing the changes in architectural information technology to understand design complexity and free-form architectural expression 	hannu penttilä 	engineering, computer science 	j. inf. technol. constr. 	 	 	pdf save alert research feed handbook of research on geoinformatics 	h. karimi 	geography 	 	 	pdf save alert research feed the good research guide: for small-scale social research projects 	m. denscombe 	political science, sociology 	 	 , save alert research feed ... ... related papers 	abstract 	topics 	 citations 	 references 	related papers stay connected with semantic scholar sign up about semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue mathematical modeling of an absorption chiller system energized by a hybrid thermal system: model validation energy procedia ( ) – - © the authors. published by elsevier b.v. selection and peer-review under responsibility of coe of sustainalble energy system, rajamangala university of technology thanyaburi (rmutt) doi: . /j.egypro. . . th eco-energy and materials science and engineering (emses ) mathematical modeling of an absorption chiller system energized by a hybrid thermal system: model validation boonrit prasartkaew* department of mechanical engineering, faculty of engineering, rajamangala university of technology, moo , klong , thanyaburi, pathumthani, , thailand abstract nowadays, global warming and energy crisis problems become serious issues which affect on all creatures on our earth. one of the best ways to simultaneously address or mitigate these problems is more utilizing the renewable energy sources instead of the fossil fuel. a solar-biomass hybrid cooling system is one of the technologies for the climate change and green-house-gas mitigation. the mathematical model of this system was developed and used in the theoretical prediction of its performance and system design. to assess the accuracy of the developed mathematical model, the obtained experimental data is then compared with the simulation results, with the same operating parameters and weather conditions. this paper presents the validation of the developed model. the validation results show that the simulation results are in good agreement with the experimental results from both qualitative and quantitative points of view. © the authors. published by elsevier b.v. selection and/or peer-review under responsibility of coe of sustainable energy system, rajamangala university of technology thanyaburi (rmutt) keywords: solar-biomass hybrid; cooling system; simulation model; validation . introduction nowadays, the global warming and energy crisis problems become the most serious issues. these problems, mainly attributed to the combustion of fossil fuel [ ], substantially affect on all life on the earth. to address these problems, the renewable energy based should be encouraged. among the energy utilization systems, cooling applications demand higher energy for their functioning [ ]. solar cooling technology is environmentally friendly and contributes to a significant decrease of the co emissions which cause the green house effect [ ]. from this point of view, solar powered cooling systems as a green * corresponding author. tel.: + - - ; fax: + - - e-mail address: prasartkaew@yahoo.com available online at www.sciencedirect.com © the authors. published by elsevier b.v. selection and peer-review under responsibility of coe of sustainalble energy system, rajamangala university of technology thanyaburi (rmutt) open access under cc by-nc-nd license. open access under cc by-nc-nd license. boonrit prasartkaew / energy procedia ( ) – cold production technology are the best alternative [ ]. as a green energy technology for the climate change and green-house-gas mitigation, a solar-biomass hybrid cooling system was proposed by [ ]. nomenclature a area (m ) cp specific heat capacity, (kj/kg.k) fr heat removal factor solar insolation on tilted surface (kw/m ) h specific enthalpy (kj/kg) m mass (kg) mass flow rate (kg/s) energy rate (kw) t temperature (k) u heat transfer coefficient (w/m k) ul overall heat transfer coefficient (w/m k) volumetric flow rate (m /s) v specific volume (m /kg) x mass concentration (%) efficiency transmittance absorptance tank load control function temperature differential control function boiler load control function heat exchanger effectiveness density (kg/m ) initial condition a ambient ab absorber aux auxiliary b boiler boonrit prasartkaew / energy procedia ( ) – bm biomass bl boiler to load c collector co condenser cg combustion gas ev evaporator f liquid state fg liquid-vapor mixture g vapor state ge generator gw gas to water hi high i inlet lo low o outlet pg producer gas set set point value st storage tank tl tank to load u solar useful energy w water we water to environment regarding the use of biomass, which is a co neutral energy source and fruitfully available in all argricultural crountries, gasification of biomass offers advantages over other sources. using solar and biomass can significantly contribute to the reduction of co emission. a theoretical study on the performance of a solar-biomass hybrid air conditioning (sbac) system has been done by [ ]. their results show that the proposed sbac system for tropical locations is feasible, and can replace conventional vapor compression systems, thus reducing the need for fossil fuel based energy systems for cooling purposes. subsequently, [ ] reported the experimental study on the performance of the sbac system. the main advantage of theoretical study via mathematical model is that the model can be used to predict all output parameters at any conditions. compared to the experimental study, the simulation results can be obtained with very low expense and less study time. the accuracy of the simulation results, however, depends on the reliability of the model. to know the reliability of developed model, the results of observed experimental results should be compared with the predicted results from the simulation with the same input parameters. boonrit prasartkaew / energy procedia ( ) – it should be noted that the mathematical model proposed by [ ] had already been validated only for some of system components using the experimental results available from a literature (no available sbac system at that time) and the proposed model has been used for the system design. the complete sbac system was subsequently constructed and test as presented in [ ]. hence, this study aims at presents the model validation, comparison results, between the simulation results predicted from the developed model [ ] and the experimental results obtained from the fabricated experimental system [ ]. section describes the proposed system relevant to the mathematical model and experimental setup. section presents the uncertainty of measurement analysis. the statistical tool for experiment and model comparison is defined in section . section reports the validation results using the comparison between the experimental and experimental results. the conclusion of study is presented in section . . system description developed mathematical model and input data figure shows the schematic of the proposed sbac system relevent to the developed model. the first part (in the left) is a solar water heating (swh) system, which consists of a field of flat plate solar collectors, a hot water storage tank and a circulating pump. the second part (in the middle) is a biomass gasifier-boiler (bgb) which consists of an automatic up-draft gasifier and a gas-fired sensible-heat boiler. the part on the right hand side is an absorption chiller (abc) which consists of an absorption chiller equiped with a fan coil unit, a cooling tower and three aqua-pumps: hot, chilled and cooling water pumps. where the details of assumptions used in the model development was presented in [ ]. solar collector p hot water storage tank controller p controller biomass gasifier- b il mm p evaporator condenser solution heat exchanger absorber p abc system generator fan coil unit cooling tower swh system fig. . schematic diagram of the solar-biomass hybrid absorption cooling system the model was developed using the following assumptions: ) the model considered the energy and mass balances at each component, and of the overall system. ) the system is considered to be at steady state ) the specific heat and density of the working fluids are constant. ) the loss of the water vapor and moisture (at the hot water storage tank and solar collector vents) is not taken into account. boonrit prasartkaew / energy procedia ( ) – ) there is no pressure loss and no heat loss/gain in the lines (pipes) connecting the system components. ) the fluid temperatures increasing due to the friction in plumbing and valves, blowers and pumps are negligible. ) the energy considered are solar and biomass energy, while the power consumed by other equipment (e.g. pumps, blower, fans and controllers) is excluded. solar water heating system the expression (eq. ( )) for collector efficiency given by the hottel-whillier bliss equation was used: ( ) where, ( ) ( ) ( ) the temperature distribution in the hot water storage tank is obtained from the energy balance expressed as: ( ) where, the extracted heat and control functions used for the collector and load energy terms, are defined as: ( ) ( ) ( ) whenever the temperature of hot water supplied to the chiller machine is lower than spt, the auxiliary heat ( aux) is needed and this required heat will be supplied by the biomass gasifier-boiler. this required heat can be determined as follows: ( ) boonrit prasartkaew / energy procedia ( ) – biomass gasifier-rr boiler- the gas-fired boiler is modeled as a heat exchanger, where heat is transferred between combustion products and water. the transient temperature of water inside the boiler can be determined by: ( ) where, the added heat into the water heater boiler and its effectiveness relations for the heat exchangers between combustion gases to water can be calculated from: ( ) ( ) ( ) where, ( ) ( ) heat losses from flue gas and from boiler surface to ambient surrounding have been considered in the overall energy supplied by the gasifier, and is given by ( ) where, the extracted heat from the boiler to meet the load can be calculated from: ( ) the consumption rate of biomass feed stock is obtained from: ( ) absorption chiller the thermodynamic model of absorption chiller was used to simulate its performance with the assumptions presented in [ ]. the effectiveness of generator can be calculated as: ( ) at the generator, knowing the hot water inlet temperature and generator heat flow, the generator temperature can be determined by the following equations: ( ) boonrit prasartkaew / energy procedia ( ) – ( ) where, ( ) ( ) for a defined solution mass fraction (range of <x< %libr) and calculated generator temperature, the saturation pressure, and can be calculated from. ( ) ( ) ( ) ( ) where, all of above cofactors can be calculated as shown in [ ]. at point , the refrigerant is in superheated state and its enthalpy, can be determined from ( ) where, ( ) ( ) . p+ ( ) the mass flow rate of dilute solution in the generator can be determined using the energy and mass balances on the generator, as: ( ) the energy balance on the generator is given by, ( ) p = p , t tt can be calculated from eq. ( ) and can then be obtained by , where and are given by the curve fit equations. the enthalpy at point can be calculated by considering the throttling process, as h = h . ( ) boonrit prasartkaew / energy procedia ( ) – ( ) the heat rejected at condenser, where , can be determined by writing the heat balance at condenser as: ( ) at the evaporator, and can be calculated from the curve fit of eqs. ( ) and ( ). ( ) from the energy balance at the evaporator, the cooling capacity at the evaporator can be calculated from: ( ) the enthalpy at point can be calculated by eq. ( ) with absorber temperature (calculated by eqs. ( ) and ( )) at the same pressure as the evaporator. the solution pump is modeled as an isenthalpic process, then . at the heat exchanger, the enthalpyy can then be calculated as: ( ) at the throttling process, . the enthalpy can be determined at the solution heat exchanger, and the absorber heat rejection can be calculated as: ( ) the minimum pump power can be determined by ( ) ( ) where, ( ) all four heat quantities must be satisfy the chiller energy balance equation, expressed as ( ) boonrit prasartkaew / energy procedia ( ) – experimental setup figure shows the experimental setup of sbac system relevent to the model used in [ ]. the collector field set for the experimental study had collectors with total area about m (the specification of solar collector is given in [ ]) connected in series and parallel (as shown in figure ). fig. . fabricated experimental setup of the solar-biomass hybrid absorption cooling system [ ] fig. . schematic diagram of the collector field set for the experimental study [ ] collector pump storage tank bgb system absorption chiller cooling tower fan coil unit controller unit data logger solar collector boonrit prasartkaew / energy procedia ( ) – . uncertainty of measurement the errors or uncertainties of the measurement are determined and used for assessing the reliability of the experiments. generally, it has two terms: relative uncertainty (reu) and absolute uncertainty (abu). for the direct measurement values, the accuracy of devices used for the measurement can be adopted asff the uncertainty of measurement. for the quantities which cannot be measured directly, their uncertainties have to be calculated based on the measured parameters [ ]. uncertainties of heat rate the uncertainties of all heat rates, e.g.: heat removal rate, depend on the uncertainties of the water flow rate, and the water temperatures at the inlet and outlet of each component. the water flow rates and temperatures are measured using flow cells and thermocouples with the same accuracy of ± . m /hr (or . kg/s) and ± . c, respectively. the relative uncertainties of heat rate at all components should be about the same level which can be calculated from eq. ( ): ( ) uncertainties of cop the cop can be calculated as [ , ]. therefore, the reu of this output variable is then be calculated as eq. ( ): ( ) uncertainties of copsysp the reu of the copsys can be calculated from eq. ( ): ( ) . statistical parameters the statistical indicators are used for the comparison between the values obtained from model and experiments results. two indicators: root mean square error (rmse) and mean bias difference (mbd) are used in the validation. if the values of mbd and rmse are close or lower than its uncertainties, it shown that the model and experimental results are in good agreement with each other. rmse is defined as eq. ( ): ( ) boonrit prasartkaew / energy procedia ( ) – mbd is defined as eq. ( ): ( ) where cic corresponds to the model simulation values, mimm corresponds to the measurements values nn is the number of data values. . validation results all parameters of the experimental system were used as input parameters of the model as shown in table . the measured solar insolation and ambient temperature of this day were also used as weather data input. the between experimental and simulation results were compared. the comparison results of each component are compared as demonstrated in figure to . the temperature profile of water at collector inlet and outlet, and the useful energy rate at the swh from both the experimental observations and model predictions are illustrated in figure . the comparison results show that the rmse of collector inlet/outlet temperatures and useful energy were . , . and . , respectively. with the same trend, the mbd of these values were - . , . and . , respectively. this indicates the predicted values by the model are in agreement with the experimental results. table . the input parameters used in the validation boonrit prasartkaew / energy procedia ( ) – en er gy r at e [k w ] te m pe ra tu re [c ] time [hr] tci tci,ex tco tco,ex qu qu,ex fig. . measured and predicted parameters of swh system figure shows the measured and predicted boiler temperature and its energy rate supplied to the chiller generator. the -data of each parameter during the steady state condition were compared. the comparison results show that the rmse of boiler temperature and energy rate supplied from boiler to load were . and . , respectively. the mbd of these values was . and . , respectively. this indicates the close prediction of developed model with the experimental results provides reliable results. en er gy r at e [k w ] te m pe ra tu re [c ] time [hr] tb tb,ex qbl qbl,ex fig. . measured and predicted parameters of bgb system boonrit prasartkaew / energy procedia ( ) – en er gy r at e [k w ] time [hr] qgen qgen,ex qev qev,ex fig. . measured and predicted parameters of abc system the heat power supplied to its generator and absorbed at evaporator during the steady state condition were compared and shown in figure . the comparison results show that the rmse of generator and evaporator heat rates were . and . , respectively. the mbd of these values was . and - . , respectively. this also indicates that the predicted values by the model are in good agreement with the experimental results . . . . . . co p time [hr] cop cop-exp. copsys copsys-exp. fig. . measured and predicted cop and copsys boonrit prasartkaew / energy procedia ( ) – finally, the measured and predicted values of cop and copsys were compared as presented in figure . the comparison result shows that the rmse of cop and copsys were . and . , respectively. the mbd of these values was - . and - . , respectively. this indicates the close prediction of developed model with the experimental results. . conclusion to know the reliability of developed model, the results of observed experimental results were compared with the predicted results from the simulation with the same input parameters. the calculated statistical parameters, rmse and mbd, of all temperature are very close to the uncertainty of the temperature measurements. the average value of rmse for temperature, energy rate and cop are . , . and . , respectively. the average value of mbd for these parameters are . , . and - . , respectively. the validation results show that the simulation results predicted by the developed model are in good agreement with the experimental results from both qualitative and quantitative points of view. acknowledgment the author wishes to thank rajamangala university of technology thunyaburi (rmutt) for providing financial support for his research. references [ ] saidura, r.; abdelaziza, e.a.; demirbasb, a.; hossaina, m.s.; and mekhilef, s. . a review on biomass as a fuel for boilers, renewable and sustainable energy reviews : . [ ] ramana, a.s.; chidambaram, l.; kamaraj, g.; and velraj, r. . evaluation of renewable energy options for cooling applications, international journal of energy sector management : - . [ ] zhaia, x.q.; qub, m.; li, y.; and wang, r.z. . a review for research and new design options of solar absorption cooling systems, renewable and sustainable energy reviews : . [ ] hassan, h.z.; and mohamad, a.a. . a review on solar cold production through absorption technology, renewable and sustainable energy reviews : . [ ] prasartkaew, b.; and kumar, s. . a low carbon cooling syste using renewable energy resources and technologies, energy and buildings : . [ ] prasartkaew, b., and kumar, s. . the quasi-steady state performance of a solar-biomass hybrid cooling system, in proceedings of the second tsme international conference on mechanical engineering (the nd tsme-icome ), krabi, thailand, - october. [ ] taylor, j. r. . an introduction to error analysis ( nd ed.), sausalito: university science books. predicting the psychological response of the american people to oil depletion and declining energy return on investment (eroi) sustainability , , - ; doi: . /su sustainability issn - www.mdpi.com/journal/sustainability article predicting the psychological response of the american people to oil depletion and declining energy return on investment (eroi) jessica g. lambert* and gail p. lambert next generation energy initiative, inc., first street, marcellus, ny , usa; e-mail: glambert.ngei@gmail.com * author to whom correspondence should be addressed; e-mail: jlambert.ngei@gmail.com; tel.: + - - - ; fax: + - - - . received: june ; in revised form: august / accepted: august / published: november abstract: oil has played a crucial role in the united states’ continued but increasingly tenuous economic prosperity. the continued availability of cheap, high energy return on investment (eroi) oil, however, is increasingly in doubt. if cheap oil is increasingly constrained, how might that impact the american psychological sense of personal and national well-being? we employ general systems theory and certain key paradigms from psychology and sociology to predict the possible societal response to global peak oil and the declining eroi of whatever oil is produced. based on these frameworks, the following three defense mechanisms seem likely to be employed by individuals and groups within society if and when confronted with stresses associated with declining oil availability. these are: denial of one’s passive helpless state, desire to establish a scapegoat, and arousal of affiliative needs and increased subgrouping. a group’s “survival” is a function of its unified sense of direction and the stability of necessary interdependencies and linkages. we suggest that the ability of the u.s. society, taken as a whole, to adapt to the stresses derived from the declining eroi of oil will increase during periods of moderate stress, and then decline after reaching its maximum ability to cope with stress. the integrity of interdependencies and linkages—power, communication, affect, and goals—must be preserved for continued social unity. americans will need to acknowledge the reality of biophysical constraints if they are to adapt to the coming energy crisis. open access sustainability , keywords: energy; eroi; maximum power principle; stress, psychological defense mechanisms . introduction over the course of modern human history, societies have experienced many periods of economic prosperity followed by decline. according to tainter [ ], odum [ ], and cleveland et al. [ ], these economic fluctuations have tended to result, directly or indirectly, from variations in a society’s access to cheap and abundant energy. events within the past few decades appear to be consistent with these patterns. the last four out of five national recessions, which have been punctuated by financial institution collapse and bankruptcy, have coincided with higher oil prices [ ]. the oil industry has historically played and continues to play a crucial role in the u.s. economy, transportation, trade, and in the maintenance of affluence, i.e., “the western way of life”. there has been more than a three-fold increase in energy consumption in the u.s. over the past years [ ]. u.s. economic well-being, national prosperity and stability is inextricably linked to the production and consumption of energy, especially oil [ ]. there is a great deal of evidence that we may be entering a period where energy and energy services are much less available to the us and other oecd (organization for economic co-operation and development) countries. for decades we as a global society have spent an increasingly greater proportion of our global energy on discovering and extracting lower quality, less accessible energy resources [ ]. growth of global oil production has stagnated since [ ]. energy return on investment (eroi), the ratio of energy supplied to society divided by the direct and indirect costs of its production and delivery [ ], provides one means of estimating the cost of oil, one which allows us to measure or estimate how much net oil is available to the economy and might be available in the future [ , ]. while this presumably provides us with more accurate and specific information on future availability than price alone, it does not address the potential effect of changes in oil availability on societal processes. it appears clear that the impending energy crisis will create technological issues and political problems. what is far less clear is the impact on societal processes and more generally on the psychological well being of citizens. there are significant differences of opinion amongst various members of the peak oil community as to how individuals and small groups within society are likely to react to the effects of the declining supplies and eroi of oil. some scientists predict that severe oil scarcity will constrain food production, exacerbate poverty in marginal sub-cultures, limit production and conveyance of essential goods and services, expand rifts among social groups, strain other limited environmental resources, and destabilize the state’s authority and ability to govern [ ]. others believe that very high-energy usage by u.s. society is not required either for prosperity or for american psychological well-being [ ]. nevertheless the most likely scenario is that americans (and others) will not be happy about any reduction in their lifestyle as measured by traditional economic criteria. many researchers believe that western societies will probably experience significant social-psychological disruption and even societal disintegration. although, sociological and psychological assessments performed in the wake of previous energy crises provide crucial components to our understanding of reductions in energy flow, so far they fail to sustainability , provide paradigms for discussing the possibility of an indefinite energy decrease that may influence the essence of western social life. no one knows for sure what the psychological or sociological ramifications of declining oil availability will be, but it is important to begin evaluating and preparing for the social aspects of what might be a very different future. we write this paper not to provide a dogmatic catalog of probable psychological consequences of these far reaching technological, political and societal issues, but rather to open a dialogue on the issues. many of the examples used, and theories stated, in this article are extreme versions of the normal psychological and sociological phenomena that occur routinely in the day-to-day functions of any group or society. this paper discusses a segment of the wide spectrum of psychological and sociological responses to extreme stresses such as those that may accompany an energy crisis of large and continuing magnitude. we propose that the main psychological response to energy-related limitations and constraints will be the production of stress [a psychological term which, as we will develop, is far more complex than the usual use of the term], a feeling that ensues because demands exceed the resources an “individual” is able to mobilize, producing physical and psychological reactions that result in mental [ ]. this mental tension will probably produce, to varying degrees, the psychological and sociological reactions described in this article. historically, a society able to procure and intelligently utilize abundant resources typically experiences economic prosperity. the opposite is also usually true; a society entrenched in an environment with scarce resources, as a rule, experiences economic paucity [ ]. if energy is as important for civilization and our economy as we believe, and if and as traditional liquid fossil fuel energy supplies decrease in quality and quantity while the human population continues to grow, we are forced to ask: “how will individuals and small groups within a population accustomed to an increasing and seemingly unending supply of cheap and abundant oil react when faced with a future of declining oil availability?”. curiously, sociologists and social psychologists have barely entered into this discussion. while limited in their education in, and understanding of, the complex technology of the peak oil and related issues, many sociologists nevertheless are competent to examine the possible social ramifications of stress more generally and the related societal processes. what we wish to do here is to apply this general expertise to the stress conditions that are likely to occur from the extensive changes resulting from depleting and ever lower quality oil reserves. a review of political and social responses to scientific pronouncements of declining oil reserves over the past decades reveals a major disconnect between scientific knowledge of depleting oil assets and societal action. political leaders, traditional economic analysts [ ], and mainstream society have largely ignored or downplayed the implications of diminishing oil reserves. the rather baffling question is: “why have repeated scientific warnings of declining oil reserves and depletion of domestic as well as foreign sources been generally disregarded?”. how are people and society likely to respond to this decline if it continues or accelerates? this is an extremely difficult but potentially important question. we turn to the general psychological literature on the response of humans to stress as a starting place for considering this question. there is substantial literature in the fields of psychology and sociology regarding the responses of people when faced with overwhelming crises resulting from war, pestilence, extended crop failure or resource depletion. we apply this literature to establish an understanding of the probable response of people to stress associated with diminishing oil availability. the objective of this sustainability , paper is to examine the possible societal and individual stress that is likely to be perceived by american society resulting from resource depletion associated with the decline of oil. . general systems theory and stress stress, in the sense the word is used in psychology, occurs when there is a union between a stressor (the cause of the stress) and the “individual” perceiving the stressor; stress cannot exist without exposure to, and perception of, the stressor. throughout this paper we refer to “stress” with the understanding that all stress exists only because it is perceived. hobföll’s conservation of resources stress model links the production of stress directly to the perceived threat of resource depletion, actual resource depletion, and lack of gain in resources following energy investment [ ]. he suggests that people strive to acquire, maintain, and protect resources and that when these resources are threatened, when there is potential or actual loss of these resources, stress is induced. while hobföll speaks of stress caused by various types of resource depletion and references ‘people’ as his level of analysis, we believe that his thinking is applicable to societal as well as individual stress. we suggest that the american public, as a whole, will experience stress as an outcome of perceived and real resource depletion associated with the decline of oil. these possible psychological and social reactions will not be limited to the individual and small group level but will be exhibited on the societal level. boulding’s general systems theory suggests that observations and analyses of behavior and actions of “individuals” (the term boulding uses to describe the unit of analysis) at lower levels may be used to understand and suggest possible behaviors and actions of “individuals” at higher levels. in other words, societies are composed of small groups, small groups are composed of individuals, individuals are composed of organs, organs are composed of cells, etc. [ , ]. while acknowledging differences associated with scale, we believe that an assessment of societal response to oil depletion using research and theory designed for smaller scale analysis may provide insight into patterns of social behavior. according to boulding, although the definition of the “individual” (unit) may vary greatly, every scientific discipline studies some sort of “individual” and each of these “individuals” exhibit “behavior”, action or change that is related in some way to the environment of which that “individual” is a part [ ]. this model, based on the premise of similar typologies among working components at various vertical levels within a society, establishes the theory of scale-free dynamics within social systems. this results in social networks that surpass the specifics of a distinct system and are inherently tied to, and reflective of, the action taken by “individuals” occupying similar roles at higher and lower levels within a network. boulding further suggests that when the individual is a human being, it is not only the person but also the roles of those persons that create the next level, the social system of which they are a part [ , ]. the connectedness between these levels facilitates analysis of behavior, actions and changes at multiple levels. in other words, observations/analyses of behavior occurring at one level can be employed to provide a better understanding of behavior occurring at adjacent levels. we believe that examining relevant individual psychological and small group sociological research, which explores individual and group reactions to experiences perceived as stressful, provides a starting point to facilitate an analysis of possible small group and societal reactions to depleting oil resources. sustainability , . general human response to stress irving janis in his book, psychological stress, developed a paradigm of general human reaction applicable to various severe stressors. janis’ research on general patterns of human response to new stressors concludes that human adjustment and response to threatening or stressful situations varies with the amount of perceived threat. these responses occur as a series of phases independent of the specifics of the stress analyzed. the more immediate an anticipated threat of danger, the greater the motivation to diminish anxiety by minimizing one’s perception of potential danger or by denying the gravity of the situation [ ]. these expressions of denial tend to be manifested by over-optimistic expectations that: ( ) minimize their perception of the probability or magnitude of the potential danger, ( ) maximize the person’s perception of their ability to cope with the danger, or ( ) maximize the person’s perception of their chances of receiving adequate help or gratification from the potentially dangerous situation [ ]. new stimuli tend to be perceived and interpreted within the context of the known and familiar and viewed as non-threatening until such interpretations are no longer sustainable. when assessing future danger, there is a tendency to extrapolate past trends linearly and draw upon previous experiences to define present circumstances [ ]. fear reactions are not extinguished; they are merely subdued temporarily until the threat is past or clear evidence of danger is brought into the narrowed focus of attention. once aware of the reality and magnitude of a significant genuine threat, individuals are forced to reconsider their optimistic assumptions, and they tend to feel and display the fear that they had temporarily managed to inhibit [ ]. as long as americans do not perceive the direct and tangible effect of declining eroi of oil, they can and will likely continue to exhibit minimal response. here the question of the pathology of denial arises. at what point shall denial be deemed pathological? experts in a myriad of fields including ecology, engineering, and economics have been ringing oil resource depletion warning bells since the s american oil crisis [ ]. to many, the arab oil embargo served as an indicator of the impact of future global peak oil, and members of the scientific community have been cautioning the world ever since [ ]. in the face of seemingly unquestionable evidence to the contrary, why have some “individuals” within u.s. society continued to deny the impending energy crisis? denial is deemed pathological if there is an unwavering rejection of a highly undesirable fact about a present situation in the face of evidence that is clearly perceived and generally regarded by others as “unquestionable” [ ]. the resulting impaired judgment appears to be the handiwork of conscious suppression coupled with unconscious repression colluding to create and maintain a “pseudo-optimistic” attitude [ ]. although it appears, at this writing, that the majority of americans have never heard of the term “peak oil” and few are knowledgeable about timelines for possible oil depletion, most have some awareness of the previous ( s) oil crisis and the possibility of repeating that scenario. we ask, “what will happen when reality sets in, when the world's oil production peak is finally conclusively verified and we start the slide back down the energy curve? will we futilely attempt to hold fast to our comforting delusions”? sustainability , . defense mechanisms associated with perceived stress according to janis, once the reality of a crisis situation has filtered through, a variety of potential defensive reactions spring to life. three of these defense mechanisms seem most likely to accompany the perceived stress associated with a possible oil crisis: ( ) denial of one’s passive, submissive state, ( ) use of “scapegoat” mechanisms, and ( ) increased affiliative needs and the formation of closely-knit sub-groups. these defense mechanisms are often accompanied by a temporary gap in memory, with retrospective distortion of pertinent facts surrounding the threatening situation [ ]. this process is a manifestation of a conscious turning away from, and an unconscious curtailing of, thought processes involved in comprehending the threatening situation. . . rejections of the passive submissive state the concepts put forth by janis are not new in psychology. anna freud, sigmund’s daughter, suggested two interrelated, unconscious defense mechanisms related to the rejection of one’s passive submissive state: ( ) identification with the aggressor, the one in control, the one with the power [ ]; and ( ) the fantasy that one can inflict the feared damage upon the aggressor, a denial of one’s actual passive, helpless state. “originally described as a defense used by children to cope with overwhelming fears of a powerful parent, this mechanism has also been observed in adults who are under the realistic threat of severe punishment from powerful authority figures…” [ ]. in these circumstances, powerless persons react to their passive submissive state by expressing the fantasy that they are the aggressor, in the “all-powerful position,” and the authority figure is passively helpless [ ]. we utilize general systems theory to indicate that this shift in perception is applicable to various positions and levels of societies: political and military leaders, politicians and societies as a whole can shift from an initial recognition of impotence to a belief that they possess the necessary power to control or at least influence the desired outcome. according to the laws of physics, power in the physical realm is defined as the ability to perform work [ ]. the ability of developed nations to perform work: to manufacture, to industrialize, to exploit, create, and maintain a strong economy, is intrinsically linked to access to and utilization of petroleum-based energy [ ]. without energy one is unable to perform work and is therefore rendered powerless. henri bérenger in summarized this position, “he who owns the oil will own the world, for he will own the sea by means of heavy oils, the air by means of the ultra-refined oils, and the land by means of the petrol and the illuminating oils. and in addition to these he will rule his fellow men in an economic sense, by reason of the fantastic wealth he will derive from oil—the wonderful substance which is more sought after and more precious than gold itself.” [ ] the intrinsic link between access to and control of petroleum and military power [ ] was clearly demonstrated during world war ii. the allies crippled the german military by targeting fuel supplies that were imperative to german military operations as well as to their industrial sector. allied forces won the infamous battle of the bulge because the germans simply “ran out of gas” [ ]. germany, with no oil and moderate amounts of coal, had insufficient energy to sustain hitler’s military machine. sustainability , the u.s. military also experienced a taste of the impact of insufficient oil on military action when general patton found his third army forces without the necessary fuel to go into battle in germany [ ]. at this time the u.s. was the major global oil supplier, producing approximately % of the petroleum used throughout the world [ ]. ownership of this massive piece of the energy pie greatly facilitated the outcome of this war [ ]. at the end of world war ii, the united states was a world super power and because it owned the oil, it did own the world and did, in an economic sense, rule over its fellow men. today, the middle east has % of the world’s proven oil reserve [ ]. the u.s. no longer commands the oil genie. although americans may continue to feel a sense of economic entitlement, this is possibly an indicator of a collective denial of u.s. economic and perhaps even military vulnerability. the major global energy holders are the middle eastern countries, controlling . % of the world’s demonstrated oil reserves [ ]. saudi arabia, alone, possesses the lion’s share, approximately %, of global oil reserves [ ]. this large and essential energy reserve provides saudi arabia and other middle eastern oil producing countries with the ability to influence production, trade, and the day-to-day activities of western culture [ ]. the u.s. energy/power position is even more untenable, because it uses some % of the world’s oil consumption while owning only . % [ ] of the world’s oil reserves [ ]. if oil does translate into political and economic power then nations in possession of abundant and easily accessed oil are truly in positions of power. the power that the u.s. once wielded as a result of controlling the lion’s share of the world’s oil has shifted. denial of this shift in energy resource power and refusal to accept the accompanying submissive state has required the implementation of a new national definition of power. today, the “american way of life” is dependent upon and is unable (with current technology) to exist without accessing energy, mainly oil, from others [ ]. to sustain this way of life, the u.s. must now rely upon military strength, diplomatic relations, and a large but deteriorating economic situation to maintain the energy flow from other nations. the u.s. military expenditures in exceeded $ billion (usd), which is % of the world’s total military budget, an amount greater than the combined expenditures of the other top nations with the highest military expenditures for [ ]. this large military budget provides a strong overseas military presence, one purpose of which is to insure the constant energy flow necessary for the perpetuation of the day-to-day activities and affluence of western culture. one measure of power is gross domestic product (gdp), the value of all final goods and services produced within a nation in a given year. u.s. gdp, currently over trillion usd, has been the largest in the world economy since the end of wwii [ ]. but here too the production and consumption of the goods and services that comprise the u.s. gdp are fundamentally reliant upon oil supplied from outside the u.s. and increasingly by middle eastern countries [ ]. the fragile diplomatic relations between the u.s. and middle eastern countries, during the post wwii era are fundamentally linked to the maintenance of the world oil trade status quo and u.s. reliance upon a world economic system that requires very large u.s. imports of oil and other basic and also manufactured resources. the arab oil embargo [ ], desert storm [ ], the “ / ” fall of the twin towers [ ], the iraq “war” [ ] and the war on terrorism [ ] are all direct or indirect manifestations of the u.s. need for foreign oil and the complex responses of both the u.s. and those who supply it [ ]. thus as the u.s. has become increasingly dependent upon imported resources, resource-rich “developing nations” increasingly are sustainability , able to impact the destiny of u.s. wealth, prosperity and, perhaps, national security. u.s. economic and military reliance on energy from potentially unfriendly foreign sources [ , ] in conjunction with the jarring reality of u.s. susceptibility to foreign attacks, heightened by the / terrorist attack [ ], has made americans aware of their vulnerability, to an extent that the u.s. populace has hither to not been exposed. in cases such as these, a sense of impotence can shift to a belief, or fantasy, that the necessary power to control or at least influence the desired outcome may be obtainable if sufficient resources are diverted to this endeavor [ ]. the demand by the u.s. to envision itself as in an “all-powerful position” has resulted in an exaggerated global military presence designed to influence oil rich nations’ willingness to abide by established western trade practices favoring u.s. economic prosperity. in conclusion, we argue that the u.s. military presence in the middle east was facilitated by a national sense of loss of international power, economic control, and less effective attempt to control the flow of oil. u.s. foreign oil dependence has grown while u.s. production has declined. thus, the u.s. is, in a sense, replacing its previous world oil prominence with extensive global military prominence. . . scapegoat mechanism janis’ second defense mechanism, scapegoating, appears initially as a latent attitude rather than overt action. according to janis, scapegoating is the wish, fantasy, or desire that “if somebody has to suffer, let it be him rather than me” [ ]. to effectively accomplish this, intolerance, bias, prejudice, and stereotypes are established enabling those impacted to deflect their frustrations to other people through the imposition of discriminatory injustices and, if necessary, death and destruction to be directed toward the “target” without guilt. these de-humanizing processes not only facilitate the establishment of a scapegoat, they justify actions which are then taken against individuals and groups defined as flawed and inadequate [ ]. this egocentric concern for one’s own well being at the expense of others yields a narcissistic disconnect from traditional moral grounding and can be accompanied by guilt and depression, and even fears of retribution, that “next time it will be my turn.” once scapegoating has occurred, these emotions and concerns for “payback” and/or revenge may result in excessive docility, apathy, and other depressive symptoms. use of de-humanizing scapegoating to justify actions taken to bolster one’s own situation is particularly likely among persons exposed to extremely stressful situations where escape is believed to be highly improbable or impossible [ ]. traditionally, conflicts between rich and poor, once played out in the streets of industrial cities, had been subdued by an increase in the wealth of the nation as a whole (i.e., “a rising tide lifts all boats”). throughout the past five decades, however, the ginni coefficient (a measure of the equitability of the distribution of wealth) steadily increased, indicating greater inequality between rich and poor. during this period american workers were relatively quiescent about this because their paychecks, even when corrected for inflation, tended to increase. that general trend has now ceased; take-home income for u.s. working families actually decreased by eight percent during the to period [ ]. this cessation of income growth is almost certainly associated directly or indirectly with a reduction in the growth rate of oil production and the net energy from it. as the growth in oil production diminishes (i.e., the sequence to “peak oil”) and the eroi of oil and other major fuels continues to decline, it seems fairly likely that the economic pie will continue to contract. sustainability , as the eroi of global oil declines, it is likely that larger portions of the “working class” population will become impoverished, fewer manufacturing jobs will be available, and the need for manual labor supporting these manufacturing jobs will continue to decline [ ]. the global manufacturing landscape has already experienced these trends. current movement towards mechanization and automation [ ] has resulted from the managerial goal of low labor cost and high labor productivity. one effect has been the displacement of workers from relatively high-paying industrial jobs [ ]. industry has turned to international competition and modern petroleum-based technology to meet its goals of enhanced productivity, with fewer workers required to accomplish the same task, and lower production costs [ ]. increased productivity has traditionally allowed both labor and management to make a greater profit, and this had played a significant role in the great wealth accrued by america throughout the middle of the last century. the ongoing trend towards computerization and robotics throughout the u.s. economy (i.e., everything from retail store self-scanning checkout stations to automated manufacturing plants) and movement from domestic production to international labor markets has resulted in higher labor productivity. the downside is a decreased need for labor within the u.s. economy, especially for the industrial manufacturing jobs that once provided enormous collective wealth for the american working class [ ]. as labor opportunities dwindle, there is a tendency to seek scapegoats on whom to blame decreased employment prospects. recent government campaigns to limit or halt immigration during periods of economic recession and high domestic unemployment [ , ] and periodic campaigns to buy products “made in america” exemplify societal responses to fears of perceived (and real) employment scarcity. increased apathy and depression manifest during extended periods of increased unemployment and decreased probability of re-employment [ ]. the desire to identify and blame the culprits behind the myriad of social and economic problems (related to the issue of decreasing cheap energy) is not limited to issues surrounding imported products and immigration. the american populace and mass media are accustomed to seeking scapegoats from among the leaders of various sectors of society for what they perceive as the inept handling of the multitude of social issues and economic crises facing the country. failing industry, banking and investment collapse, and government policies and decisions have been subject to government committee investigation, media scrutiny, and become common topics of conversation across the united states [ ]. without regard for the political party currently in power or the decisions currently being made, americans choose to blame those on wall street, the various ceos and cfos of industry, the white house, and the politicians on capital hill for the current “state of distress” rather than recognizing the increasing reality of the end of growth of oil and cheap energy [ ]. . . affiliative needs and sub-grouping janis reports a third response to perceived stress: an arousal of affiliative needs (the desire to associate with others that hold or espouse similar ideologies and commonly perceived needs). this group-level defense mechanism is likely to occur during highly stressful moments, especially when the danger of being injured or killed is imminent [ ]. this is usually expressed as an unusually high need for companionship and affection among individuals within the group [ ] and coincides with a willingness to drop normal psychological barriers. when a large group of people are faced with impending demise or physical damage, these strong affiliative needs tend to result in the formation of sustainability , sub-groups of individuals of like minds within the larger group [ ]. factions of strangers may experience a sudden sense of unity when exposed to perceived danger. for example, the american citizenry’s reaction to the terrorist attack on the united states on september and its aftermath exemplifies this psychological and sociological response. america’s momentary abandonment of conventional social barriers (e.g., strangers on the streets of new york city embracing and consoling one another immediately following the twin tower collapse) and subsequent societal communion reflect strong affiliative needs during a time of perceived stress. acts of increased patriotism in the form of increased flag purchases, flag flying, and bumper stickers espousing nationalistic phrases clearly support the presence of this phenomenon. a simple comparison of u.s. flag sales for wal-mart stores, inc. on september ( flags) and september ( , flags) versus those purchased on the day of the attack, september , ( , flags) and the following day, september , ( , flags) [ ] demonstrates an immense and immediate pro-american communal response to the attack and perceived threat of attack [ ]. this intense single-minded nationalism eventually shifted to the formation of sub-groups espousing varying levels of anti-terrorist/pro-american affection as variations in perceptions became apparent [ ]. currently the u.s. retains access to an abundant although expensive supply of oil. declining oil reserves and production, in both the u.s. and the world, however, will likely lead to a disruption in oil supply and eventual damage to the u.s. social, political, and economic framework [ ]. the current popular call for “fiscal responsibility” is an example of societal reactions to this new perceived scarcity. disruption of the societal framework by interruptions in oil supply, at least in the short-term, is apt to rekindle the intense affiliative needs and subsequent sub-grouping behaviors observed in the aftermath of the / terrorist attack. it is possible that these affiliative needs and resulting re-kindled like-minded groups espousing a “we versus they” mentality may result in the u.s. exercising diplomatic and military measures to secure resources (oil) necessary to ensure the continued “american-western way of life”. . . net-effect of employment of defense mechanism the net effect caused by the employment of these modes of defense is the formation of an illusion of personal invulnerability. survival of one or more dangerous situations tends to reinforce these feelings [ ]. the arab oil embargo first exposed the precariousness of the us-opec oil trade. the resulting severe fuel shortage produced numerous energy saving policies (e.g., reduced speed limits) and technological changes (e.g., installation of residential solar hot water panels and production of smaller automobiles). after oil availability and prices returned to previous levels, energy saving efforts and concerns about oil availability waned. apprehensions were assuaged, american life returned to normal, and speed limits and the size and power of most american automobiles gradually climbed. this reaction is not unlike that of wwii british air-raid victims studied by janis. air-raid victims reported that although they immediately sought shelter upon hearing the first air-raid sirens, they did not continue to do so for subsequent sirens. even though initially they were quite certain that they were going to be killed, when the all-clear signal went off without incident, they felt secure that they were in no danger. having survived a previous strike(s), they continued their routine activity during subsequent sustainability , air-raid attacks; they no longer felt threatened and did not seek shelter even though some were killed [ ]. this is an extreme example of denial of vulnerability and desensitization, a psychological process where repeated exposure to a fearful circumstance significantly alters the subsequence responses. although the threat produced by the arab oil embargo was not life threatening, as was the london air strikes, it was the first oil shortage, controlled by foreign nations, experienced by u.s. citizens. the u.s. experienced domestic peak oil production in the lower states in the early s [ ]. this coincided with the rise of opec, the usurpation of aramco and other subsidiaries of multinational oil companies by saudi arabia and other opec states, and the quadrupling of the price of oil in – [ ]. this brush with peak oil and oil shortage provides a window into the psychological and sociological responses of the american people to the relatively high intensity stresses of declining oil availability. the subsequent reduction in oil availability resulted in short fuel supplies, higher fuel prices, long queues, and consumer supply limits [ ]. what followed were severe recessions, inflation [ ], and a loss of jobs [ ], in other words a very large stress to our society. the acuity of the ’ oil crisis led to an almost ubiquitous realization by the american people of u.s. dependence on oil for the maintenance and support of its economic machine. while some within the u.s. sought a more aggressive solution to the problem of obtaining oil from foreign sources [ , ], the prevailing opinion within the u.s. populace was that government should take a more passive role in international affairs, be cognizant of its limitations, and focus on domestic problems [ ]. denial of one’s passive submissive state does not seem to have played a significant role in the u.s. response to the oil crisis of ’ . while the ’ oil crisis did represent a strong stress event in u.s. history, it is important to distinguish this event from our current circumstances as u.s. oil production at that time accounted for almost percent of domestic oil needs [ ]. additionally, the opec embargo accounted for only a percent reduction in u.s. oil consumption [ ]. unlike our current energy situation, the u.s. was perceived as a powerful energy producer and was largely immune to the whims of foreign states. this decrease in oil availability was generally met with strong opposition. according to belk et al., most american consumers failed to see themselves and the general public as a major cause of the energy crisis [ ]. as president carter indicated, many americans “deeply resented that the greatest nation on earth was being jerked around by a few desert states”. [ ] the u.s. populace sought scapegoats in opec countries, the governments of large oil-importing nations, oil companies, and portions of the public that were perceived as wasting finite energy resources [ ]. the choice of scapegoat depended upon an individual’s perception of “personal responsibility” for the energy crisis. belk et al. found that those individuals that ascribed the collective problem of energy shortages to personal causes were more likely to place the locus of blame on the general public and typically preferred conservation solutions. conversely, individuals that attributed the collective problem of energy shortages to non-personal causes were more likely to blame oil companies and generally favored government actions against these firms [ ]. these stark differences in causal attribution further divided the public along ideological lines and increased sub-grouping phenomena [ ]. as the decade progressed, the u.s. populace continued to express concerns over the u.s. energy situation. throughout the s u.s. majorities indicated that, as a nation, the u.s. was investing “too little” in the development of the country’s energy resources [ ]. the iranian revolution, the subsequent energy crisis, and the events that followed radically influenced u.s. foreign policy. sustainability , strikes, demonstrations, and protests curtailed iranian oil production and export leading to reduced oil availability and higher gas prices [ ]. in addition to issues experienced during the previous energy crisis, the u.s. populace was forced to face its impotence in thwarting the september election of fidel castro as the leader of the non-aligned movement, the november iranian hostage crisis, and the december soviet invasion of afghanistan. the american public’s skepticism of détente and the intensions of its southerly neighbor were strengthened after intelligence uncovered the existence of a soviet combat brigade in cuba [ ]. the following month, castro assumed his role as leader of the non-aligned movement, a position that afforded cuba, a perceived enemy of the u.s., with influence over opec and other critical oil producing nations [ ]. to add insult to injury, castro delivered a statement on april , that permitted the unrestricted exodus of cuban nationals. in the months that followed almost , cubans arrived in southern florida [ ], many of whom were perceived as “social undesirables”. cuba’s benefactor, the then ussr, further threatened u.s. foreign oil interests. a harris poll concluded that a percent majority thought the soviet invasion of afghanistan was a strategy to acquire “more influence over the oil-producing countries of the middle east.” [ ] as yankelovich and kaagan stated, the american people “felt bullied by opec, humiliated by the ayatollah khomeini, tricked by castro, out-traded by japan and out-gunned by the russians” [ ]. the stress from these energy related circumstances increased affiliative needs and unified the american people toward a common purpose. a poll conducted by yankelovich, shelly, and white, found an percent majority believed that the iranian situation had helped to unite the nation [ ]. opec, the ayatollah khomeini, castro, and the ussr presented the u.s. populace with ready scapegoats on whom blame for the ’ energy crisis could be attributed. the disquieting realities of late and early left the american people frustrated, angry, and anxious over america’s novel but pervasively submissive role as an international leader. faced with the perception of a strategically weaker america, loss of prosperity, and a plethora of failed, impeded, or ineffective foreign policy initiatives, the u.s. populace experienced a decided change that historian commonly identify as a watershed event [ ]. president carter’s remarks are a testament to america’s perceived sense of emergency, “let our position be absolutely clear: an attempt by any outside force to gain control of the persian gulf region will be regarded as an assault on the vital interests of the united states of america, and such an assault will be repelled by any means necessary, including military force” [ ]. carter’s inability to act decisively to effect these sentiments in the eyes of the american people ultimately led to the election and ascension of the reagan administration; a decidedly different leader charged with redefining america’s posture of assertiveness [ ]. the american people had grown tired of foreign bullies and wished to reject their passive submissive state by adopting a tougher stance in the international arena. u.s. government dealings with “troublesome” opec nations, during the decades that followed, have been persistently bellicose, determined to avert the loss of control experienced in the wake of the energy crisis [ , ]. conversely, the american people were far quicker to forget the tumult of the late s and early s [ ]. when the embargo ended and oil prices returned to previous levels, life returned to “normal”; the instability and volatility of the oil trade was largely ignored or denied by the american populace. the economic rebound of the late s and s left the people of the u.s. with a false sense of invulnerability and in a state of denial regarding the severity of the sustainability , energy crisis situation and only a vague, lingering, perception that eventually long-term changes would be required to facilitate continuous acquisition of foreign oil [ ]. . impact of intensity and duration of exposure to stressors according to torrance, for groups to survive, they must have, at a minimum, a unified sense of direction or path that, if followed, will assure survival and stable patterns of interdependencies and “linkages”. torrance suggests that clarity in both of these areas is essential to group survival [ ]. the connections and relationships, or linkages that he refers to are the distribution of power within the group, the establishment and maintenance of communication networks, the emotional bonds among members, and the communal goals of the group; these act as the “glue” that bonds group members to one another. torrance further proposes that a group’s success at maintaining this “glue” is mediated by the variables of duration and intensity of stress. according to torrance, groups exposed to unabated stress will eventually experience fatigue, the breakdown of essential linkages and finally collapse. he notes that groups may vary dramatically in the length of time required to reach collapse and that the intensity of stress experienced influences this time frame. before the breaking-point is reached, a variety of positive and negative effects may occur; prior to their demise, groups under stress may initially flourish. the ability to adapt to stressors and flourish is facilitated or thwarted by the effectiveness or ineffectiveness of the previously defined linkages. torrance’s research suggests that bonds among group members will initially increase with increased perceived stress. increased bonding will occur until an apex is reached where, although perceived stress may continue to increase, a decline in the strength of these bonds will begin to occur causing disorganization and eventual disintegration of the group. seyle’s differentiation of two types of stress: eustress and distress [ ] describes similar reactions to that described by torrance. when response to a stressor enhances the functioning of the individual, it is considered a positive coping response: eustress. this positive response to stressors continues until some theoretical apex is reached. at this point, according to torrance, although the intensity of stress may continue to rise, a decline in the strength of integrating bonds is likely to occur, causing disorganization and eventual disintegration [ ]. seyle defines this as distress; when stressors persist, unresolved via coping mechanisms and adaptation, distress results. one’s experiences, expectations, and resources available for coping with the stressor, as well as the duration of exposure to the stressor, influence the outcome [ ]. figure is our visual conceptualization of torrance’s ideas on the impact of duration and intensity of perceived stress on group integration. the x-axis represents the duration of a group’s exposure to stress. the y-axis denotes the intensity or degree of stress to which a group is exposed. a society exposed to moderate degrees of stress for a moderate amount of time has the capacity to exist and perhaps thrive under stressful conditions (area c). area b of this graph illustrates that persistent, unabated stress negatively impacts a group’s ability to perform the necessary integrating maintenance functions that assure survival and stable patterns of interdependencies and linkages. area a illustrates the impact on a group exposed to sufficiently extreme stressors; the group’s ability to perform integrating maintenance functions will suffer. in other words, groups not only experience a breakdown in their integrative functions when exposed to sufficiently intense stress (area a), they also experience a breakdown in these functions if consistently exposed to varying degrees of unabated stress [ ], sustainability , without regard for the intensity of that stress (area b). the graph suggests that in combination these two facets of perceived stress: intensity of the stressor and duration of exposure to a perceived stress, result in group breakdown and eventual collapse. it suggests that not only can a group’s maximum coping capacity be exceeded but also when this is exceeded, the integrative activities that bond segments of the group together no longer adequately function and a breakdown of that group results. examples of societal breakdown or collapse resulting from exposure to extreme stress over a short period or modest exposure over a prolonged period are rare. this dearth of historical examples may be due to the complex inter-group dynamics between large social states. societies exposed to modest degrees of stress for long periods may dissolve completely (e.g., the decline of easter island [ ]) or may be subsumed by another social state (e.g., the fall of rome to the germanic tribes [ ]). societal breakdown resulting from acute traumatic stress usually follows war or natural disasters and may be accompanied by a period of societal decline (e.g., the fall of athens to sparta [ ]). it is important to note that all societal collapses are complex, multifaceted, and result from a variety of causal factors. figure . the interaction of two independent variables: intensity of a stressor and the duration of perceived stress- the impact on group integration. . torrance’s model applied to future decline of oil applying general systems theory, we extrapolate societal response to the perceived stress of declining oil availability from general individual and group level responses to stress. we suggest that when groups are conceptualized or envisioned as the collective ‘individuals’ within a society, torrance’s model of group reaction to intensity and duration of stress can be used to examine societal reactions to stressors that vary in intensity and to which exposure is continuous and unabated. we suggest that torrance’s model can be used to understand the stress introduced to western society sustainability , by declining oil. because oil is a critical non-renewable natural resource, inherently limited and finite, the eventual yet inevitable decline of oil is likely to introduce societal stressors. it will not act as the sole stressor and it may not cause social disintegration or collapse. rather, it is intrinsically linked with economic, political, and social factors (the underpinnings of an industrial society) that could, if the u.s. persists in a business as usual mentality, unite to produce the breakdown of society [ ]. there will undoubtedly be vast differences in the length of time required for various societies, under the stressors associated with the declining eroi of oil, to reach a “breaking-point” or enter a decline in organization and integration. however, if and as this breaking-point is reached, negative effects including confusion, inefficiency, recklessness, apathy, fatigue, hostility, and changes in leadership may be exhibited [ ]. we already see some signs of what we perceive as response to declining eroi as the increasing difficulty of governing in the united states at all levels and increasing political hostility of the different political parties. as we apply torrance’s paradigm to describe possible responses to stressors resulting from declining oil, we recognize that the ability to adapt may be either facilitated or thwarted by the strength of a society’s interdependencies and “linkages”; the glue binding that society together [ ]. the distribution of power, communication networks, emotional bonds, and communal goals within a society normally act as the “glue” bonding members with one another. they unite to form a network of connections that result in a society’s perceived sense of unity and that society’s ability to effectively perform integrating maintenance functions [ ]. according to torrance, as stressors increase, the ability to perform increases until there is a maximum linkage efficiency and effectiveness is reached. if exposure to stressors continues unabated, the linkages binding groups together weaken and the forces “tearing apart” the group exceed the forces maintaining it. we suggest that torrance’s model of the impact of stressors on social interaction, when envisaged as a plotline, resembles an inverted u-shaped curve. figure conceptualizes the effect of varying exposure to stressors on interdependencies and linkages that bond various portions of society to one another. for the purpose of this study we will call this inverted u-shape the ‘bonding force curve’. the bonding force curve applies torrance’s paradigm, describing societal reactions to perceived stress, to an inverted u-shaped curve model of the dynamic relationship between societal bonding forces and perceived stress. the curve’s inflection point represents the level of bonding at which a group’s performance of integrating maintenance functions becomes de-coupled by increased stress resulting in a decline in a group’s bonding forces. a variety of authors have found similar empirical inverted u-shaped curve phenomenon related to stress and performance (e.g., wade’s analysis of the relationship between resource scarcity and cooperation [ ]). even if the conceptualization of the inverted u-shaped curve is highly simplistic and unable to fully account for the complex relations between humans and their environment [ , ], the proposed model should be considered useful in a global context. given this theory, we suggest that societies would derive some cohesive benefits from stressors inherent to the declining eroi of oil. these benefits may occur as a heightened sense of societal bonding derived from effective communication, constructive use of power, optimistic affect, and shared collective goals. these benefits will likely continue until society reaches the maximum theoretical advantage derived from increased perceived stress. once this apex is exceeded, the fabric of society will begin to unravel. sustainability , unfortunately, it is impossible for us to predict or define where the u.s. currently rests on the curve; only in retrospect will we be able to apply a timeline to this trend. figure . according to torrance, as stress increases bonding forces increase until a theoretical apex is reached. a decline in the strength of integrating bonds then occurs even though the intensity of stress continues to rise. . . communication communication, potentially the most readily apparent linkage among group members, is likely to be compromised under high degrees of perceived social stress. according to torrance, the following conditions appear to be the most prominent in weakening communication linkages necessary for survival within the group [ ]: ( ) failure of a group member to inform others of what he/she is doing [ ], ( ) failure to pool information which would provide a basis for diagnosing the seriousness of the danger and reducing resistance to acceptance of its seriousness [ ], ( ) confining communication to dyads or cliques rather than to the entire group [ ], ( ) failure to use group judgments in making decisions, and the use of leadership techniques which interfere with this type of communication [ ], ( ) power differences which interfere with communication of information needed in decision-making [ ], and ( ) unwillingness to disagree in the decision-making process [ ]. torrance suggests that vertical communication, under stress that is perceived as moderate, becomes more frequent with increasing intensity and/or duration of stress. once the degree of perceived stress exceeds the group’s ability to effectively handle that stress, not only will vertical communications become less frequent, they will become muddled, often reaching only a select few within the group [ ]. sustainability , famous examples of the impact of truncated vertical communication include president nixon’s infamous watergate team [ ] and president kennedy’s bay of pigs crisis [ ]. applying general systems theory to torrance’s research, which means assuming that the societal level will be the same as the group level, we suggest that leaders of nations experiencing crisis situations are likely to direct fewer communications to the lower status group: the general populace. those in positions of leadership will instead probably engage in lateral communication within a trusted leadership group while simultaneously reducing vertical communications directed toward mainstream society. the result will be that mainstream society will receive limited and delayed information concerning details of the crisis situation. according to torrance, the opposite is also true at the group level; when lower group members perceive a large power distance between themselves and their leader, those lower group members may not feel accountable or obligated to communicate pertinent decision-making information with those in leadership positions [ ]. to elucidate the severity of consequences to truncated communication within groups, torrance recounts a story of a lieutenant colonel who was observed, by four crew members, to be sitting on his unattached dinghy during an over-water bail-out. the lieutenant colonel perished as none of these crewmembers felt an obligation to communicate his situation to him [ ]. the combined effect of these diminished communication processes at both the group and societal levels is miscommunication, poor judgment, and incorrect decisions, sometimes with large consequences. the establishment of effective communication among intergovernmental groups has, historically, been a common problem in government. historically, this issue has been exacerbated by the propagation of competing objectives and personal agendas [ ]. recent united states environmental protection agency (epa) and pentagon failures to communicate on superfund sites [ ] provide an example. a second example of competing agendas and poor communication is the funding of a -megawatt wind energy production venture between u.s. and chinese energy groups (u.s. renewable energy group, cielo wind power lp, and shenyang power group) in western texas [ ]. designed to bring renewable energy as well as installation and managerial jobs to the area, this project was stalled by negative press and congressional concerns regarding the manufacturing source (china) of component parts for the $ million (usd) grant [ ]. many of these communication and agenda issues have been addressed through the formation of federal government oversight taskforces and workgroups intended to target specific policy and social issues perceived as having overlapping or parallel agency efforts. still, many groups seeking to maximize their own ability to receive “adequate gratification” from and cope with the impending oil crisis continue to exploit existing divisions amongst federal, state, and regional agency efforts. unless these communication and coordination issues are purposefully addressed and a common thread of understanding is reached, communication among groups will continue to be threatened by intra-group and inter-group stress. . . leadership and power according to torrance, during times of perceived crisis, vertical communication tends to decrease and leadership groups typically do not seek decision-making input from lower-status individuals within the group [ ]. there is constriction of control and limited downward informational communication to those in lower levels of the social hierarchy, as this is deemed non-essential and sustainability , perhaps dangerous [ , ]. reduced vertical communication results in perceived social isolation from the leader, loss of confidence, and an aversion to further expansion and structuring of leadership. a breakdown in shared understanding between leaders and members of a group, results in greater horizontal informational communication within the social network/group [ ]. we suggest that deterioration of hierarchical communication between the leaderships and the “rest of society” will compound any existing stress associated with the declining eroi of oil. according to katz, excessive stress may result in conflict within the current leadership group [ ]. this is especially true if blame is attributed to members of the leadership [ ] and typically corresponds with changes in authority and the leadership process [ ]. d.w. conrath’s codicil to torrance’s research further elaborates upon changes in the leadership process; the expansion and structuring of leadership is directly linked to conditions of high perceived stress within the leadership sub-group [ ]. the range of judgments considered by leaders during the decision making process is a function of group members’ willingness to disagree. the correctness of a decision is positively related to the range of judgments considered [ ]. under conditions of extremely structured and consolidated power, low status persons are more reluctant to express their thoughts and opinions for fear of being found in opposition to high status individuals. inability to communicate true opinions frequently leads to miscalculations in policy decisions and often makes the difference between continued societal unity and societal disintegration [ ]. the third reich and german anti-semitic sentiment are eloquently instructive on this point. the anarchy, chaos, and resource scarcity of the post-wwi era lead to changes in the german authority (from kaiser wilhelm ii eventually to hitler [ ]) and leadership process (monarchy to democracy to fascism [ ]). the extreme structure and consolidated power of the nazi regime following the severe stress of the post-wwi era, coalesced to produce a populous that willingly turned a blind eye to atrocities performed on people they previously called their neighbors. this example, while extreme, demonstrates the complete passivity of people under high degrees of stress when faced with the fear of being found in opposition to authority figures. expansion and increased structuring of leadership (i.e., the systematic hierarchical and horizontal organization of leadership to establish, guide, and direct uniform compliance with group policy) during periods of perceived stress, is evidenced in almost every historically prominent government “power grab”, e.g., julius caesar [ ], napoleon [ ], and hitler [ ]. structuring of the government, in these cases, was preceded by widespread societal fears of perceived crisis. individually, group members typically do not desire expanded leadership and/or additional structuring of leadership [ ]. a group’s collective unconscious desire for direction and individual lethargy when faced with the gravity of a crisis situation, colludes to produce a perfect scenario for a political “power grab” and leadership structuring. under these conditions, democratic processes tend to fail, liberties are eroded, and power is centralized under a central power figure or group. history has a way of repeating itself. unless constructive changes to current energy policy are formalized and implemented, the united states may experience continued restructuring of leadership and progressive centralization of political power. sustainability , . . affect and goals positive group affect (the emotional milieu within a group) and group activity focused on the formation and attainment of group goals increase during moderately stressful conditions and are followed by a rapid decline upon reaching an apex of stress. this pattern occurs in situations of high intensity stress and/or when stressors continue unabated over a prolonged period of time [ ]. a group’s capacity to survive is dependent upon its skills in organizing its efforts. as a result, disorganized groups show signs of disintegration more readily than organized groups. the ability of a group to coalesce and maintain clarity of purpose is dependent upon its capacity to perform quick, adequate analyses of novel situations, provide clear and concise uniform communication among all group members and maintain the group goal of survival [ ]. random trial-and-error behavior, resulting from a lack of clarity of purpose and insufficient information, is detrimental to the attainment of group goals [ ]. the u.s. involvement in vietnam provides an example of altered group affect and splintered goals during a period of societal exposure to intense, unabated stress. after a very brief period of unified goals and optimism, the u.s. populace plunged into emotional turmoil and diametrically-opposing objectives [ ]. this was a situation marked by intense as well as unabated stress as u.s. [ ] military troops were exposed to guerrilla warfare on a scale and dimension never previously experienced. as the atrocities of jungle mayhem, news of the day’s carnage, and seemingly astronomical american casualties blared across tv screens, the american populace splintered into factions; those opposing the war demonstrated in washington and rioted on college campuses; those supporting the war effort picketed and campaigned for order at home [ ]. the ability of the u.s. to quickly and adequately analyze its military situation was compromised, factions of society were set in opposition to one another, and the emotional tenor of the country as a whole was one of distress, all of which are recognizable signs of social disintegration. similarly, poorly organized effort and lack of clarity of purpose are currently evident in the unplanned development of renewable energy. there is an abundance of government and privately funded research in a sundry of “green” energy arenas with little coordination of efforts or evaluation of their net energy contribution. experimentation within the transportation industry alone includes everything from ethanol to bio-diesel to hydrogen fuel cells, each of which is highly subsidized, highly subject to hype and rarely analyzed by objective science [ ]. industrial energy research areas include everything from effectively harnessing wind, to capturing solar energy using photovoltaic cells, and from diverting river and tidal currents, to growing algae, corn, and willow biomass. each area initially promises to “solve” the potential u.s. energy crisis resulting from decline in oil reserves, yet each falls short of the necessary eroi to be considered an alternative comparable to oil [ ]. if a nearly comparable solution is not found, disillusionment will likely follow. the uncertainty, engendered by unclear and contradictory communications and goals, will likely result in a breakdown of each individual member’s ability to accurately decipher and predict their current and future circumstances [ ]. this may result in unstable group affect (depression, apathy and ultimately surrender into hopelessness) as we face the real possibility that there may not be an effective and efficient alternative to the energy on which we so completely depend [ ]. sustainability , . integration vs. disintegration hamblin found, “present in every crisis situation is a solution that requires the cooperation of all or most of the members of the groups involved” [ ]. during a crisis situation with no apparent solution, integration does not increase, rather it decreases. as each progressive solution fails, frustration mounts, and individual attempts at survival occur. groups disintegrate when faced with a threatening situation and the solution involves individual competition. this pattern of evoked responses appears to be based in a simple rational model: if the likely solution to a crisis requires cooperative action, group integration increases. group disintegration results when the crisis situation appears to either have no solution or the optimum solution requires individual action. according to hamblin, groups remain together only if there are valid and functional reasons [ ]. society will remain intact only while there is a unified purpose that benefits the society as a whole. if the u.s. continues to dissipate its remaining energy on futile efforts to maintain a “business as usual” mentality, then the american public will squander its remaining opportunities to work together with unified purpose; to prepare for the energy crisis at hand. seyle’s general adaptation syndrome (gas) concurs with hamblin’s research on group disintegration. seyle’s research demonstrates stress reactions where the intensity of stress is so great, it exceeds the organism’s maximum effective coping ability. gas theory suggests that if stress exceeds an individual’s ability to effectively cope (for our purposes, the point of optimum societal bonding/unity) then the reaction appears to follow a three-stage process: recover or resistance, exhaustion, and burnout [ ]. seyle’s period of recovery or resistance is similar to the decreasing efficiency and effectiveness of society (evidenced by the initial declining side of the curve, figure as it clings to traditional energy practices while attempting to remediate the current energy crisis. seyle’s, torrance’s and hamblin’s paradigms all concur that should stress-causing events continue unabated, exhaustion sets in, followed by symptoms of burn-out including diminished responsiveness to the needs of others [ ]. groups disintegrate [ ] and as each progressive solution fails, frustration mounts, and individual attempts at survival occur [ ]. . the power of unified purpose a society with a unified vision for resolving its “real” energy issues has the capacity to alter its projected energy path [ ]. concentrated focus on a crisis situation retards social growth and can exacerbate existing calamities [ ]. a clear vision of a desired outcome leads to clarity of purpose among group members, a unified collective objective, and more coordinated pooled resources to achieve the desired outcome. only through the application of unified purpose will the u.s., as a collective, be able to mediate its voracious use of energy and effectively utilize its remaining resources to wean itself from dependency on oil. abraham lincoln’s comment appears salient; “you cannot escape the responsibility of tomorrow by evading it today” [ ]. the current challenge for the u.s. and other energy intensive, oil driven western cultures is to develop a shared vision for an energy independent future that: ( ) acknowledges the biophysical constraints of reality, ( ) effectively envisions the true collective objective, sustainability , ( ) clearly states goals, and ( ) establishes flexible and evolving methods of implementation [ ]. we suggests that unified purpose and vision would result in a comprehensive, adaptive, integrated, and biophysically-based process based on a collective understanding for reducing current and anticipated u.s. oil consumption. in practical terms, a unified purpose would provide the u.s. with a social process to determine how to best use existing natural resources, employ sustainable practices, and plan for an “energy independent” future. the actions we take today have the potential to exponentially affect the world of tomorrow. if steps are taken to avert the coming energy crisis and develop a low energy intensive society, we may still be able to avert many, and possibly all, of the above outcomes. . summary we have developed a framework for understanding possible western societal reactions to stresses caused by the depleting quality and quantity of oil reserves by applying boulding’s understanding of general systems theory to janis’, torrance’s, and hamblin’s work on individual and small group reactions to stress. we examined past societal responses to perceived stress and possible future adaptive behaviors to energy (oil) scarcity using psychological and sociological frameworks originally designed for behavioral analysis at the individual and small group levels. the u.s. has defined its energy security by extrapolating its current and future energy circumstances from an examination of its history. historically, the u.s. has been capable of producing and procuring, for the last century and a half of rapid economic growth, all of the oil required for the “american way of life”. with few exceptions, it has been able to do so unfettered by the biophysical realities of finite energy resources. as a result, the u.s. populace has generally ignored scientific evidence of depleting oil reserves and remained immersed in the day-to-day minutiae of life. we suggest that, if and when serious oil shortages become a reality, three defense mechanisms: denial, establishment of scapegoats, and an increased need to affiliate are likely to be employed to facilitate the continuance of this american myth of plenty and perception of invincibility. u.s. foreign policies in the middle east are manifestations of the interactive effect of all three defense mechanisms. the first defense mechanism is demonstrated as denial of the severity of u.s. dependence on foreign oil from countries with whom it is on less than friendly terms and the impact of this dependency. continuous and favorable foreign oil trade is necessary for the maintenance of the u.s. and world economic status quo. the sense of and actual vulnerability created by this dependence on favorable foreign oil trade with potentially hostile nations helps establish a second defense mechanism: the sometimes latent, sometimes active, wish to establish scapegoats on whom aggression can be expressed and blame may be placed. this de-humanizing process facilitates discriminatory injustices and is used to justify aggressive actions taken by the u.s. against individuals, groups and nations defined as flawed and inadequate. prejudicial stereotypes and cultural intolerance, once established, permits acts of aggression to be perceived as justified and perpetrated with minimal culpability. individuals holding and espousing similar ideologies and embracing similar stereotypes find themselves drawn to one another. this increased need to affiliate with (the third defense mechanism) and share common opinions, beliefs, and feelings with like-minded people results in the sustainability , formation of sub-groups such as political splinter groups. this shared sense of unity culminates in a “we/they” mentality, perpetuating stereotyping, scapegoating and aggression. these defense mechanisms work in concert to create an exaggerated sense of invulnerability and a willingness to assert power, in the form of military might, in order to ensure the steady flow of oil necessary to maintain the world economic status quo and a sense of entitlement and justification. we suggest that, despite continued scientific evidence of peak oil, oil depletion, and declining eroi, the u.s. populace will continue to exhibit these psychological and sociological defense mechanisms on a broad societal scale until sufficiently clear, irrefutable evidence to the contrary brings about a shift in perception and changes in actions. as the gap between increasing u.s. oil consumption rates, declining eroi of oil, and oil depletion expands, demands for government intervention programs (designed to combat growing unemployment and poverty) will probably increase. at the same time, economic paucity and recession will result in calls for decreased government spending cutting these very programs. as a result, the division between the “haves” and “have-nots” in american society will likely bolster affiliation within sub-groups on different sides of the issue. the influence of intense and unabated individual and societal stress created by the inevitable decreasing quantity and eroi of oil will likely adversely impact the interdependencies and linkages that bind society together. the impact on communication is clear: truncated communication not only separates leaders from their populace, it limits information flow. the result is poor decision-making at a time when quick, adequate analyses of new information and circumstances coupled with clear, concise, uniform communication among all group members is essential. faced with seemingly impossible challenges, a dearth of solutions, and unabated stress, leadership groups, the leaders and political party in power are likely to seek expanded influence and increased structure resulting in larger, more centralized political power. the american populace, driven by fears of economic and social repercussions resulting from oil depletion, will probably experience lethargy and an unconscious desire to be guided by those in positions of power. the gravity of the impending energy crisis, and the possibility that there may not be an adequate alternative to oil, will likely result in discordance between the american populace and those in positions of leadership. it is probable that this discordance will result in disillusionment within the populace and expanded and increasingly mistrusted and maligned centralized leadership. the capacity for the united states to alter its current and projected economic and energy course is dependent upon its leaders’ abilities to formulate and effectively communicate a clear vision and unified purpose in the energy field, establish clear renewable energy goals, commit to a rigorous energy-use reduction plan, prioritize energy research, and implement an energy policy that creates a viable energy future. the american populace will need to acknowledge the reality of biophysical constraints, and embrace a renewable, energy efficient “american way of life”. acknowledgements we are grateful for the valuable assistance and constructive comments received from susan lambert, bess lyon, 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(accessed on november ). © by the authors; licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution license (http://creativecommons.org/licenses/by/ . /). a comparative study on a built sun tracker and fixed converter panels | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /ijeoe. corpus id: a comparative study on a built sun tracker and fixed converter panels @article{shama acs, title={a comparative study on a built sun tracker and fixed converter panels}, author={f. shama and g. h. roshani and s. roshani and a. ahmadi and saber karami}, journal={int. j. energy optim. eng.}, year={ }, volume={ }, pages={ - } } 	f. shama, g. h. roshani, + authors saber karami 	published 	engineering, computer science 	int. j. energy optim. eng. producing non-polluting renewable energy in large scale is essential for sustainability of future developments in industry and human society. among renewable energy resources, solar energy takes a special place because of its free accessibility and affordability. however, the optimization of its production and consumption processes poses important concerns, essentially in the affordability issue. this paper investigates several optimization and performance issues regarding solar panel… expand view via publisher igi-global.com save to library create alert cite launch research feed share this paper citationsbackground citations view all topics from this paper 	mathematical optimization 	graph (discrete mathematics) 	table (database) 	accessibility 	apache axis citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort 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semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue doi: . /s - ( ) - energy policy ( ) – energy subsidies in california’s electricity market deregulation alexander ritschel*, greg p. smestad international environmental policy program, monterey institute of international studies, monterey, ca , usa abstract deregulation and re-regulation of california’s electricity market not only failed in terms of anticipated cost reductions, improved customer service and higher competition, it also led to the introduction of various additional energy subsidies. this paper analyzes california’s electricity market deregulation process from a subsidy viewpoint. under deregulation in california, investor-owned utilities were not allowed to pass their energy procurement costs fully on to their customers, and therefore subsequently, and inevitably, ran into severe financial problems. such retail price regulation is an energy subsidy that is both economically and environmentally unfavorable, because it veils true price signals to electricity consumers and, in this way, discourages energy conservation. other policies implemented in california that represent perverse energy subsidies are the purchase of power by the state of california, the suspension of retail competition, and the potential misuse of money from the recovery of stranded costs. many interventions implemented by the state to smooth out the impacts of the energy crisis insulated electricity consumers from market realities, supported the existing structure of california’s electricity market, which is predominantly based on fossil fuels, and suppressed market incentives to improve energy conservation. r elsevier science ltd. all rights reserved. keywords: energy subsidies; electricity market deregulation; california energy crisis . introduction all over the world, governments are deregulating their electricity markets to increase competition, lower costs and promote innovation. in california, the most important step of deregulation was introduced on march , when all residential customers were allowed to buy competitive retail electric power. expectations about the benefits were high. cost reduc- tions were anticipated due to increased production efficiency as a result of wholesale competition, more efficient retail pricing structures, and enhanced techno- logical development. a study by the us depart- ment of energy estimated that the average national price of electricity would be % lower under competition by (doe, ). besides cost reductions, other benefits were also expected, including improved custo- mer services, increased number of new products avail- able, improved levels of service reliability, and added environmental benefits due to customer-driven prefer- ences for the so-called ‘‘green’’ power such as that from biomass, wind and solar energy. however, wholesale prices in california after dereg- ulation were higher than before, californian businesses and residents have experienced brown-outs and black- outs, and retail electricity prices have been raised for most consumers. in addition, one of the two major investor owned utilities (ious) faced bankruptcy and the governor had to declare a temporary state of emergency. one year after the introduction of competi- tion into the retail electric power market, of the more than companies that initially expressed interest in marketing electricity directly to customers, all but had pulled out. up to now, just . % of residential utility customers and . % of commercial and industrial customers have switched their supplier, representing . % and . % of customer load, respectively, (shioshansi, ). the reasons why deregulation failed so dramatically in california are complex. the most important flaw of california’s deregulated electricity market was that the market was more re-regulated than deregulated. what paul joskow of mit has referred to as ‘‘...the most complicated electricity market ever created...’’ was a *corresponding author. current address: th street no. , sacramento, ca , usa. tel./fax.: - - - . e-mail addresses: alexander ritschel@yahoo.com (a. ritschel), gsmestad@solideas.com (g.p. smestad). current address: sol ideas technology development, p.o. box , pacific grove, ca , usa. - / /$-see front matter r elsevier science ltd. all rights reserved. pii: s - ( ) - mismatched combination of a deregulated wholesale market with price controls in the retail market for up to years (joskow, , p. ). if consumers are insulated from wholesale market prices, they will not adjust their use of energy (e.g. through conservation), and this inevitably results in supply shortages. when demand is very inelastic and supply constrained, wholesale prices soar, giving generators the opportunity to exercise market power by withholding capacity. this is believed to have happened in california (joskow and kahn, a, b; hall, ). another shortcoming of the restructuring process was that the california public utilities commission (cpuc) required california ious to divest a substantial portion of their generation assets, while it did not require them to establish long-term power purchase agreements with the new owners. the ious, still regulated by the cpuc, hesitated to enter into long-term contracts, because they feared the mandatory review and approval process of these contacts by the cpuc. this led to a complete dependence of the utilities on the highly volatile spot market to procure their customer’s unmet electricity needs and drove wholesale prices even higher. to solve the energy crisis in california, the state of california stepped in to purchase electricity on behalf of retail customers in the iou’s service areas. the governor of california also introduced financial in- centives to hasten the building of new power plants, and to decrease demand for electricity. this allowed the ‘‘lights to be kept on’’ while the ious raised their electricity rates less than what was needed to recover their costs. however, the policies to address the crisis veiled true price signals to consumers and are, therefore, not compatible with a fully deregulated and competitive electricity market. ideally, deregulation should produce a smooth transition to a more competitive, market- based economy with less government intervention and regulation. many policies introduced in california influenced the electricity market through governmental intervention and not through market-based price signals, and can thus be considered energy subsidies. this paper analyzes california’s electricity market restructuring process to date, and shows that some elements of this process can be regarded as an introduction of additional subsidies, which are likely to lead to greater economic inefficiencies and environ- mental damage. in the sections that follow, california’s deregulation law will be outlined, energy subsidies will be defined, and the main elements of california’s deregulation and re-regulation will be discussed in light of a subsidy framework. these policies include retail and wholesale price caps, stranded cost recovery, and state power purchases. our analysis provides an example for policy makers who wish to implement a more compe- titive electricity market that benefits the economy and the environment. . california’s deregulation process in , california became one of the first states in the us that restructured its electricity supply industry. it followed the british example of electricity market deregulation, which started in and had already achieved substantial cost reductions a few years after implementation. a cost benefit analysis of the british deregulation experience estimates an overall benefit of d to d : billion, which is equivalent to a permanent reduction of electricity prices of . – . % from levels (newbery and pollitt, ). the framework of california’s restructuring plan was established by the electric utility industry re- structuring act (ab ), which was unanimously enacted in august by the state legislature. before restructuring, each california utility provided its customers with generation, transmission, distribu- tion, metering and billing of electricity. after restructur- ing, customers were allowed to choose their electric power supplier. restricted transmission and distribution facilities were opened to all power generators on a fair and equitable basis and were overseen by a new organization, the independent system operator (iso). electric power was traded at the newly created power exchange (px), where power producers com- peted to sell their electricity generation in response to bids submitted by buyers. besides the establishment of a competitive wholesale and retail market for electricity, the deregulation bill authorized the recovery of stranded costs for utilities. under the old regulatory environment, california’s ious made mandatory in- vestments in utility infrastructure that became uneco- nomic in the new competitive marketplace. assembly bill provided an opportunity for the utilities to recover these ‘‘stranded costs’’ by collecting a manda- tory charge from virtually all customers and by securitization of parts of their stranded costs. the restructuring legislation also established funding for public interest programs, such as conservation, research and development, and renewable energy resource development. . energy subsidies an important economic aspect that is often neglected when formulating energy policy is subsidies to energy production and consumption. historically, the rationale for the introduction of energy subsidies has been to stimulate economic growth and to enhance the security of energy supply (de moore, ). this goal was mainly addressed through reduced electricity retail prices for industrial customers to boost industrial development, or the px ceased functioning in january . a. ritschel, g.p. smestad / energy policy ( ) – through various production incentives for electricity generators. undoubtedly, there can be some benefits for society due to energy subsidization. however, one should not overlook possible negative side effects. in order to evaluate the impact of an energy subsidy one has to balance the positive and negative implications to the welfare of the society. in many cases, the often unintended, negative side effects are higher than the benefits. myers ( ) defines subsidies with an overall adverse effect on the society as ‘‘perverse’’. he estimated annual global energy subsidies to be $ billion, of which $ billion are perverse subsidies (myers, ). energy subsidies have positive impacts if the subsidies correct market failures. for example, they can stimulate the development of energy technologies with environ- mental benefits that would not be adequately supported in fully competitive markets. they can also enhance the reliability of the electricity system, provide affordable energy to low-income groups, or guarantee the security of the energy supply system. some energy subsidies, introduced for environmental reasons, are an obligation to generate a certain amount of electricity using renew- able energy technologies (e.g. renewable portfolio standards), or impose minimum energy efficiency requirements. although clearly environmental benefi- cial, these obligations may not be the most efficient policy instrument. fischer and toman ( ) point out that indirect subsidies, which mandate or protect certain technologies, are almost always a less efficient policy option compared to policies that penalize polluters, e.g. through internalization of external costs. many energy subsidies have been constructive at the time of their introduction, but have later become adverse economically or environmentally. often, energy subsidies were introduced long before the environment was of any real concern to governments. besides, some negative effects of the combustion of fossil fuels, such as global warming, became evident only recently. in general, most energy subsidies are detrimental both to the economy and the environment in the long run. negative effects of energy subsidization are (bruce, ; myers, ): * energy subsidies aggravate governments’ budget deficits and divert government funds from other programs with possibly higher benefits to the society. * subsidies produce economic efficiency costs, because resources are allocated so as to take advantage of subsidies rather than market profitability. * subsidies produce equity costs, because they tend to benefit few at the expense of many. * most energy subsidies are harmful to the environ- ment, because they support polluting energy technol- ogies, or they encourage increased energy consumption. globally, only $ billion are annually spent to subsidize renewable energy technologies and end-use energy efficiency programs, compared to $ billion per year supporting fossil fuels, and $ billion per year for nuclear power (van beers and de moore, ). . . defining and measuring energy subsidies in its service report, the us energy information administration defined an energy subsidy as ‘‘any government action designed to influence energy market outcomes, whether through financial incentives, regula- tion, research and development (r&d) or public enterprise’’ (eia, ). subsidies can be categorized as either production or consumption subsidies. energy production subsidies increase the prices received by producers, while con- sumption subsidies reduce the prices paid by consumers, typically through price controls that set energy prices below their full cost. while both kinds of subsidization take place in most countries, developed countries use energy subsidies primarily to support producers. the above stated subsidy definition is very broad and includes direct cash disbursements to consumers or producers, tax policies (tax credits, tax exemptions, tax deductions), public provision of infrastructure, public r&d expenditures, implicit subsidies (government loan or liability guarantees, debt forgiveness), price regula- tions, special government procurement practices, import and export tariffs, and many other forms of direct and indirect governmental interventions in the market. most subsidies other than direct subsides, which are recorded in the national budgets, are very hard to measure and can only be estimated. one can find several other, much narrower, definitions of energy subsidies in the literature, which cover only those subsidies that can easily be measured and for which data is readily available. basically, there is no single correct subsidy definition, and the decision how broadly or narrowly to define a subsidy should be based on practical criteria (bruce, ). this paper analyzes energy subsidies in california. the analysis will be based on the very broad subsidy definition from the us energy administration informa- tion stated above. the aim of this work is to point out the additional energy subsidies that have been intro- duced in the course of the electricity market deregula- tion process in california. it is beyond the scope of this paper to measure them exactly. however, rough estimates will be given in those cases where data was currently available. a crucial point for the measurement of a subsidy is the choice of the baseline. the baseline is the counter- factual environment in which the subsidy does not exist. this hypothetical situation is often assumed to be a fully competitive, undistorted market. however, in the case a. ritschel, g.p. smestad / energy policy ( ) – of energy subsidies, one has to consider that electricity markets, even if they are liberalized, are never perfectly competitive. the usually low number of generators, the very inelastic price elasticity of demand for electricity, and the high cost of electricity storage make it easy for competitors to manipulate the market. to mitigate potential market manipulation, some form of oversight and regulation by an independent authority, such as the federal energy regulatory commission (ferc) in the us, is necessary. technical issues, such as network constraints, imperfect registration of demand, and the uneven distribution of suppliers with different produc- tion and transmission cost and different ability to adjust the output to the varying demand require the control of the electricity system by an iso. both the ferc and the iso have a regulatory function and, therefore, interfere with the electricity market and make competition imperfect. these considerations suggest that the ‘‘ideal’’ deregulated electricity market requires some regulation, which is an energy subsidy according to our definition, in order to work effectively and produce maximum welfare. in this paper, the reference, against which energy subsidies have to be measured, is an imperfect competitive electricity market with some form of state or governmental regulation. . . benefits of subsidy removal despite the many obvious negative effects of most energy subsidies, in most countries very little progress has yet been achieved in removing them. this is because, in general, many subsidies are hidden and, therefore, unknown or at least very difficult to quantify. on the other hand, once introduced, subsidies create special- interest groups and political lobbies, defending their persistence despite their negative implications for society’s overall interests. a comprehensive analysis of the barriers to subsidy removal and a strategy to overcome them can be found in van beers and de moore ( ). removal of most energy subsidies will have a beneficial environmental impact. two independent studies (dfi, ; dja, ), using slightly different assumptions, estimated that the environmental gains of reducing energy subsidies in the usa range from to million tonnes of carbon dioxide annually avoided. this would lead to a . – . % decrease of total annual us carbon dioxide emissions (eia, ). at a global scale, removal of all coal subsidies would reduce global carbon dioxide emissions by % (anderson and mckibbin, ). a study by the international energy agency (iea, ) found that removing consumer subsidies in eight large non-oecd countries could cut their carbon dioxide emissions by up to %, which would reduce global carbon dioxide emissions by nearly %. subsidy removal is also likely to benefit a nation‘s economy in the long run. burniaux et al. ( ) show that the removal of energy subsidies to consumers in non-oecd countries would increase global welfare by $ billion. removing subsidies will lead to greater fairness, meaning that only people who consume a certain good or service pay for it and its affiliated environmental costs. a clear, undistorted pricing of goods and services improves economic efficiency and national welfare. subsidy removal is also likely to increase flexibility in the energy sector, promote long- term economic growth, benefit employment policies, facilitate international trade, and reduce government spending and help balance the budget (oecd, , , ). to ensure that energy markets facilitate improve- ments in energy efficiency, environmental protection, and investment in supply infrastructure, the energy ministers of the member countries of the asia-pacific economic cooperation adopted in the following non-binding energy policy principle: ‘‘consider reducing energy subsidies progressively and promote implemen- tation of pricing practices which reflect the economic cost of supplying and using energy across the full energy cycle, having regard to environmental costs’’ (apec, ). california’s electricity market restructuring could have been an opportunity to reduce government regulation, reduce energy subsidies and enhance efficient pricing. however, the way california restructured lead in the opposite direction, at least in the short run. in the sections that follow, we will describe and discuss several key aspects of california’s deregulation that involve energy subsidies. these include retail price caps, recovery of stranded costs, and public benefit programs. table summarizes the findings of the present study. . retail price cap california assembly bill mandated a freeze of electricity rates for each class of customer at their levels on june , . the rate freeze period started on january , and was to continue until the date on which utilities’ stranded costs have been fully recovered. residential rates for electricity generation were frozen at a relatively high level of about . cents (us) per kwh (pg&e, ). this provided an opportunity for the ious to recover their stranded costs. in the first years after deregulation when the utility’s costs to purchase energy were lower than the capped retail price, utilities could use the difference to recover their stranded costs. the price difference is called the ‘‘competition transition charge (ctc)’’ and is given by the amount of revenues from the monthly bills paid by consumers minus the utility’s costs to purchase energy at the px, the a. ritschel, g.p. smestad / energy policy ( ) – transmission and distribution costs, the costs of public purpose programs, and nuclear decommissioning. during the first years of the transition period, when px prices were low, utilities could recover significant parts of their stranded costs by collecting a positive ctc charge. from early summer onwards, however, px prices spiked and the utilities’ energy procurement costs became higher than the frozen retail cap. beginning in june , the wholesale price of electric power in california increased to an average cost of . cents per kwh for the period from june to december , compared to an average cost of . cents per kwh for the same period in (pg&e, ). thus, the ctc became negative. as a consequence, the cpuc allowed the utilities on january , to collect a surcharge of cent per kwh, called the ‘‘electric emergency procurement sur- charge’’. since this surcharge turned out to be insuffi- cient to reduce the negative ctc, the cpuc adapted an additional, tiered usage surcharge on march , , called the ‘‘energy procurement surcharge’’, which is on average about . cents per kwh. despite the addition of the two surcharges to the frozen retail rate, the utilities’ costs of energy procure- ment, delivery, transmission, public purpose programs, and nuclear decommissioning remained higher than the revenues from ratepayers, resulting in a continuously negative ctc from may until july . the northern california utility ‘‘pacific gas & electric company’’ reported an under collection of $ . billion as of december , , the southern california utility ‘‘southern california edison’’ reported for the same period an under collection of $ . billion (barrington- wellesley, ; kpmg llp, ). the cost imbalance of one utility is depicted in fig. for illustration purposes. the cpuc allowed the southern california utility ‘‘southern california edison’’ the full recovery of the undercollected power procurement costs including the interest expenses in a resolution in january (cpuc, a). the northern california utility ‘‘pacific gas & electric company’’ filed a plan of reorganization with the bankruptcy court on september , . once the plan is confirmed and becomes effective, the plan is expected to allow the utility to restructure and refinance its business. until then, it is unknown who will finally pay for the past undercollected power procure- ment costs. however, even in the case that also the northern california utility will be able to fully recover its past undercollected power procurement costs through future electricity rates paid by its retail customers, the retail price cap can be regarded as a subsidy to consumers. the price cap deferred parts of the electricity costs to be table summary of subsidies introduced in california’s electricity market deregulation and re-regulation process policy subsidy perverse subsidy comments retail price cap yes yes electricity consumers were insulated from market price signals stranded cost yes yes unclear legislation of recovery california’s deregulation law allowed the potential misuse of the proceedings from the rate reduction bonds by the incumbent utilities public benefit yes no support of energy efficiently, programs r&d, renewables, and low-income customers power purchases yes yes suspension of retail competition increase of supply yes no support program for the accelerated construction of various new power plants reduction of demand yes no around % reduction in energy use achieved due to various energy conservation programs wholesale price cap no no cost-based price cap imposed by ferc as defined by the us energy information administration, an energy subsidy is ‘‘any government action designed to influence energy market outcomes, whether through financial incentives, regulation, research and development (r&d) or public enterprise’’ (eia, ). subsidies with an overall adverse effect on the society are defined as ‘‘perverse’’ (myers, ). a. ritschel, g.p. smestad / energy policy ( ) – paid into the future and, thereby, insulated the customers from market price signals that reflect funda- mental scarcity. as a result, electricity consumers had little incentive to save energy. since the price elasticity of demand for electricity is negative, albeit rather small, one could have expected at least a modest reduction in electricity use, if the price cap had not been in place and prices had risen. the california energy commission (cec, ) estimates the short-run residential electricity demand elasticity between � : and � : ; the commercial short-run elasticity between � : and � : ; and the industrial short-run elasticity between � : and � : : other studies (branch, ; hsing, ) estimate the short- run residential demand elasticity between � : and � : ; well within the range stated above. the price capped electricity service at a rate at, or below, wholesale prices also discourages consumers to switch to alternative retailers and is therefore anti- competitive. in addition, price caps cause producers to look to other markets in the short run, and deters investments in new capacity. the overall effect of retail price caps is therefore that they increase demand and reduce supply. this is exactly the opposite of what a deregulated market is expected to do, and this led to an escalation in the california energy crisis. . recovery of stranded costs one of the main issues in the transition process from a regulated to a competitive electricity market is the recovery of stranded costs. stranded costs are typically defined as costs of historical investments and contrac- tual obligations, which would be recovered by the incumbent utility under the prior regime of cost-of- service regulation, but which will not be recovered under the reduced price level, which is expected to result from competition. a more detailed definition can be found in california assembly bill (california public uti- lities code, , section (f)). the california utilities estimated their stranded costs to amount for $ billion (hirst, ). there are several critics of stranded cost recovery who claim that it is unfair and produces economic ineffi- ciency (penn, ; michaels, , ; navarro, ). however, we believe that the recovery of stranded costs, as long as these costs are properly measured and defined, does not distort competition and should not necessarily be regarded as a subsidy. recovery of stranded costs, if done correctly, relieves incumbent utilities from the legacy of sunk cost of the old regulatory regime and creates, therefore, a ‘‘level playing field’’ in the new, competitive marketplace. a compre- hensive analysis of this aspect can be found in tye and graves ( ), kahn ( ), joskow ( ), and baumol and sidak ( ). stranded cost recovery by itself does not distort competition, if the amount of stranded costs is determined by an appropriate and accurate methodol- ogy, and if it is ensured that the proceeds are used ja n ap r ju l o kt ja n ap r ju l o kt ja n ap r ju l o kt u s d o ll a rs i n m il li o n s total electric revenues total electric costs s fig. . comparison of southern california edison’s electric revenues collected from its customers and the utility’s costs of power purchases, including other costs associated with electric industry restructuring, for the time period between january and december . area s represents a negative competition transition charge of approximately $ . billion (data source: kpmg llp, ). a price elasticity of � : describes the fact that the electricity demand falls by . % due to a price rise of %. a short-run period describes a period of time, in which consumers response to a price increase is limited to adjusting existing equipment (e.g. changing the thermostat setting) rather than replacing existing appliances with more energy efficient ones. a. ritschel, g.p. smestad / energy policy ( ) – without impeding competition or distorting the market. ideally, the legislation should ensure that utilities use the granted compensation to cover losses associated with the sale of stranded assets or the retiring of uneconomic financial obligations. without such provisions, there is the danger that utilities will use the granted funds in an anti-competitive or inefficient way. the california legislature allowed two forms of stranded cost recovery (california public utilities code, sections (s), (w), , (a), (e)). the first option is by collection of a mandatory charge, called the ctc on all customer bills during the transition period. the ctc is equal to the difference between the frozen electricity rate charged to consumers and the utility’s costs of purchasing and delivering power. this ctc was discussed previously. the second option of stranded cost recovery per- mitted by the california ab is called ‘‘securitiza- tion’’ or ‘‘asset-backed financing’’. it requires a ‘‘financing order’’ by the state’s public utilities commis- sion approving parts of a utility’s stranded costs to be recovered. this is accomplished by means of a mandatory charge, called the ‘‘fixed transition amount’’, applied to all residential and small commer- cial customer’s energy bills. the ownership to all revenues arising from the fixed transition amount is defined as ‘‘transition property’’. under securitization, the utility sells this transition property to a special- purpose entity, usually a securitized trust. the special- purpose entity is financed from the issuance of ‘‘rate reduction bonds’’ in the form of notes or certificates to investors. the bonds are amortized and the bondholders are paid by the revenue stream arising from the mandatory charge to the utility’s customers. proceeds from the issuance of the bonds will be transferred back to the utility in form of an up-front ‘‘lump sum’’ payment in return for the transition property. in california, both stranded cost recovery approaches were used (ctc and securitization). the two major california ious issued $ . billion in rate reduction bonds through the state’s infrastructure and develop- ment bank in december (pg&e, ; sce, ). stranded cost recovery by securitization can be regarded as a subsidy to incumbent utilities, if they can use the proceeds of the issuance of the rate reduction bonds in their generation business without restrictions. this is anti-competitive, because it permits the incum- bent utility an undue competitive advantage in the new marketplace. the california legislature defines rate reduction bonds as ‘‘bonds, notes, certificates of participation or beneficial interest’’ ..., ‘‘the proceeds of which are used to provide, recover, finance, or refinance transition costs and to acquire transition property’’ (california public utilities code, section (e)). in the bill’s language ‘‘transition costs’’ basically mean stranded costs, and ‘‘transition property’’ stands for the ownership of the stream of payments that collateralizes the rate reduction bonds. besides this definition, there is no clear restriction on the use of the proceeds of the securitization financing. deregulation laws in other states are much more restrictive. the pennsylvania legislation, for example, provides that the pennsylvania public utilities commission has the over- sight of the disposition of the bond proceeds, which are to be used primarily to reduce stranded costs (pennsyl- vania house bill / , section (b)( )). there are suspicions that some california ious used the proceeds of their issued rate reduction bonds at their holding company level in an anti-competitive manner (turn, ). in , the president of the california utility ‘‘san diego gas and electric’’ noted that cash from stranded cost recovery was opening a billion dollars in new investment opportu- nities for his company (brydolf, ). thus, the unclear definition of the legal use of the proceeds of the issuance of the rate reduction bonds in the california assembly bill can be regarded as a subsidy to incumbent utilities. the advantage of securitization for the utilities and their shareholders is that the recovery of their securitized stranded costs is guaranteed and received immediately. the alternative way of stranded cost recovery through the ctc just provides an opportunity for the utility to retire its stranded costs over the time of the transition period, because the amount of the revenues from the competitive transition charge depends on the utility’s unknown cost of energy procurement. the advantage of stranded cost recovery by secur- itization for ratepayers is questionable. advocates of securitization, which are mainly utilities, argue that it can produce savings for ratepayers. this assumption is based on the usually higher credit ranking for the securitized assets than that of the utility. the credit enhancement is possible because of the character of the ‘‘financing order’’ by the state public utilities commis- sion, which defines a property right by statute to receive the proceeds of the fixed transition amount. the interest imposed on the rate reduction bonds will therefore be lower than the utility might otherwise obtain if it had to recover its stranded costs by the issuance of utility bonds and rely on its own bond rating. some economists, however, point out that securitization does not necessa- rily lead to economic savings for ratepayers (michaels, ; awerbuch and hyman, ). in order to accurately compare the two debt financing options, either by the issuance of utility bonds or by securitiza- tion, one has to consider the risk differential, the different payback periods, and the discount rate. securitization is likely to benefit ratepayers only if capital markets have systematically overestimated the utility’s risk to default on interest payments. a. ritschel, g.p. smestad / energy policy ( ) – . public benefit programs one provision of ab is the creation of various public benefit programs for improvements in energy efficiency, energy-related research and development, support of renewable generation, and support of low- income customers. the public benefit programs are financed through mandatory charges for all retail customers of ious based on their electricity usage. the funding level of the programs is around $ million per year. the public benefit surcharge adds only – % to the price of a kwh, since california’s electricity costs about $ billion per year. the public benefit programs succeed the former demand-side management (dsm) programs that were carried out by california investor owned utilities (ious). the cpuc ordered california ious to imple- ment dsm programs with the aim to shape total customer demand to better match system generating requirements and system costs. this helped utilities to improve system performance, reduce load, and cut down costs. the statewide utility spending on dsm programs varied over time. it started with $ million a year in , grew to $ million a year in , fell below $ million a year in , and rose again to about $ million a year in (cec, ). with the utility restructuring process starting in the mid- s, ious were no longer required to continue their dsm programs and the california assembly bill , therefore, ordered the implementation of the above mentioned public benefit programs. the funding for these programs is currently allocated as follows (cec, ; cpuc, ): * about $ million per year for energy efficiency programs. * $ . million per year for the public interest energy research (pier) program, which supports energy related research, development, and demonstration projects that are not adequately provided by compe- titive markets and aim to advance science or technology. * $ million per year for the renewable energy program, which supports existing, emerging, and new renewable energy technologies. * about $ million per year for support of low- income electricity customers through the reduction of their electricity bills, and through improvements in energy-efficiency. the public benefit programs are direct energy subsidies provided for environmental and social reasons. the programs are in the public interest, because the funded projects are not adequately undertaken in competitive markets due to various impediments and market failures. in the case of energy efficiency improvements, consumers and businesses often lack the information, tools, or correct incentives to identify and implement energy saving choices that would benefit them. another important market failure is that the environmental and social costs attributed to electricity generation are not included in the market price for electric power, resulting in artificially reduced prices. if electricity prices do not reflect their full costs to society, consumers cannot make rational economic investments in energy efficiency. the development of clean energy technologies are impeded by factors that include market, institutional and legislative barriers. market barriers involve unequal subsidies and tax regulations, while institutional barriers result from a small industrial base for emerging technologies that hinders effective bargaining. legisla- tive barriers, for example, include unfavorable legal requirements for renewable energy sources. the public benefit programs are subsidies that are in the best public interest. energy efficiency programs reduce the energy intensity, make businesses more competitive, and allow consumers to live more comfor- tably. by reducing the electric system loads, the programs increase the power system reliability, reduce the need for new capacity, improve the environment, and stimulate the economy. studies show that recent energy efficiency programs in california have been cost- effective and returned at least two dollars in benefits for every program dollar spent (cec, ). in addition, the pier program is very likely to show significant economic benefits for the state of california. a benefit evaluation of the pier program, which was at the time of the writing of this article in its early stages, analyzed out of pier projects that were expected to result in commercially available products or informa- tion in the near future. the analysis estimates the public benefits of the analyzed projects at around $ million (jenkins et al., ). considering that not all projects have yet been evaluated and that the pier program has been in place only years (with a cumulative funding of $ million), one can reasonably expect that the benefits of the whole pier program will significantly exceed its costs as additional products and information emerge from ongoing projects. this is in accordance with other r&d programs in the energy sector. for example, r&d expenditures of the gas research institute in illinois, incurred between and , produced a benefit to cost ratio of . to (bournakis, ). up to august , the renewable energy program supported approximately mw of existing renew- able capacity and about mw of new renewable capacity via production-based competitive auctions. it aims to increase the percentage of california’s electricity generation from renewables from % in to % by (excluding large hydroelectric a. ritschel, g.p. smestad / energy policy ( ) – power). renewable energy technologies show high environmental and economic benefits compared to fossil fuel-based electricity generation. a recent study from the electric power research institute (epri, ) finds that renewable-energy resources could cost-effectively contribute up to % of california’s electrical energy demand (excluding large hydro) by . this would create over , jobs, and reduce electricity genera- tion-related emissions of air pollutants by at least %. it would also lead to a % reduction in co emissions and a % reduction in nox emissions, compared to a scenario where all needs for capacity addition in the next decade will be filled with natural gas. the cumulative value of the avoided emissions would exceed $ . billion by . . actions undertaken to fix the energy crisis the main elements of the plan to manage the crisis in california were (state of california, ): * keep the lights on. the ious could not purchase energy to meet their customer’s needs. that is the rationale behind why the state stepped in and began purchasing one-third of the total electricity needs in the ious’ service areas. * increase supply. the construction schedules of the private sector contractors who were building new power plants were accelerated by providing them with financial incentives to finish the job in time to bring new power on-line for the summer of . that added approximately mw: * decrease demand. through a program of education and demand management programs, the overall demand was reduced about % over the previous year. * discipline the wholesale market. ferc reluctantly placed a temporary price cap on wholesale prices of electricity in the western states. each of these actions can be examined in the light of energy subsidies (see table ). . . power purchases by the state of california due to the poor financial situation of two major ious in california, the state of california stepped in as a power purchaser after january . this allowed the lights to be kept on in california. from january , , until december , , the state is expected to have spent $ . billion through the department of water resources (dwr) for energy on behalf of california’s ious (cpuc, b). however, the state’s general fund will be fully reimbursed according to a decision of the cpuc in february (cpuc, b). the department of water resources will collect its revenue requirements through charges remitted from billings to retail custo- mers of the three major california electric utilities. although, in the end, no taxpayer’s money will have been used to finance the state’s power purchases, the mitigation action by the governor of california can be regarded as an energy subsidy according to the definition stated previously. the power purchases by the state helped to amortize (and smooth) the peaks in the cost of energy during , sparing california’s economy from the shock of trying to absorb all of the added cost at one moment. this intervention prevented a scenario, where widespread disruption in electricity supply would have occurred, due to the illiquidity of california’s ious, which hindered them from purchas- ing power for their customers. on september , , the cpuc suspended the right of customers to acquire direct access electric service from independent power retailers (cpuc, ). the motive for this decision was to provide the three californian ious with a stable customer base in the future, from which to recover the cost of the power the dwr has purchased. with this decision, the cpuc prevented a scenario where customers switch from utility service to independent electric service providers to avoid higher electricity rates due to the charges associated with the repayment of the department of water resources. the most important element of deregulation, namely customer’s choice to select their energy service provider, was thereby removed. this action is a subsidy to the ious, because it essentially abolishes competition in the electric retail market. the decision provides a large advantage to incumbent utilities, since, under ab , state oversight was reduced, and now they can again operate as monopolies. the ious and the newly created california power authority will be able to pass electricity costs to ratepayers, without having to compete against indepen- dent power providers. the decision is also unfavorable from an environmental perspective, because so called ‘‘green’’ service providers, offering renewable energy, are banned from entering the direct market. this prevents customers from choosing cleaner energy products, such as geothermal, wind, biomass, or solar power. of course, they can enter into contracts with the ious. . . wholesale price cap wholesale electricity prices in california have risen more than -fold since the spring of . while the wholesale market price for electricity averaged . (us) cents per kwh in , it skyrocketed to cents per kwh in with peak prices of $ . per kwh (state of california, ). there are suspicions that the whole- sale price increase was not only due to a supply–demand a. ritschel, g.p. smestad / energy policy ( ) – imbalance, but was also caused by the exercising of market power by generators and marketers (joskow and kahn, a, b; hall, ). for this reason, the ferc introduced a price mitigation plan on june , (ferc, ). the mitigation seeks to correct dysfunc- tions in the wholesale power market of california, and the remainder of the western systems coordinating council (wscc) that is responsible for the majority of electric generation in the western us. the price mitigation plan consists of two parts that cover every hour of spot market sales of electricity in california and the wscc. during reserve deficiency hours, i.e. when reserve levels in the iso are below %, the bids of sellers that own generation are limited to the marginal cost to replace gas used for generation plus variable operation and maintenance costs. during all non-reserve defi- ciency hours, spot prices are to be capped at % of the highest iso hourly market-clearing price established during the hours of the last stage alert when reserves were below %. in both cases, sellers are allowed to justify bids above maximum prices. the price mitigation plan of the ferc introduces cost-based price caps. the price cap is based on the marginal cost of the economically least efficient generating unit dispatched, which is very likely to be fired by natural gas. this price mitigation plan reflects prices in a competitive market, where the market-clearing price is also set by the marginal cost of the last unit of energy produced. for a more detailed analysis of the wholesale price mitiga- tion plan see shioshansi ( ). we conclude that such cost-based wholesale price caps should not be considered as subsidy. a price cap will distort the market only if it is set too low, i.e. below the short-run marginal cost of production. in this case the cap will deter production from an existing power generation facility. the maximum price of the ferc price protection plan is, however, based on costs of production of the least efficient generating unit dis- patched. furthermore, justified bids above maximum prices are allowed. thus, the price cap will not deter production, but will deter the exercising of market power from excess generators since they will lose an incentive to restrict output in order to drive the price higher. . . programs to increase supply and reduce demand for electricity one reason for california’s electricity market break- down was the imbalance of power demand and supply. the power reserves dropped several times during summer of to alarmingly low levels, resulting in very steep wholesale price increases. the reason for the constrained capacity situation was not an unexpected increase in demand. california’s electricity consumption has been rising by about % annually during the last decade, and this pattern did not change in . the peak demand in summer of was actually lower than in . the power reserve levels dropped in mainly due to electricity imports that were suddenly reduced. while california has historically been relying on out-of-state generators for about % of its electricity needs, imports fell to % in , because the neighboring states had less excess capacity to export (cec, ). the state of california addressed the supply–demand imbalance by passing new laws to expedite approval of new power plants and introduce aggressive energy conservation programs. the goal was to increase generation capacity by ; mw by july , so that the supply exceeds demand by %. the california state program to increase capacity consisted of a rapid certification and construction of new ‘‘peaking’’ power plants, the accelerated construction of already approved base load power plants, and the raising of power output from existing power plants. it is difficult to assess if the plan to increase capacity should be considered as energy subsidy or not. although the new peaking power plants are typically small simple cycle gas power units, the program also provides for renewable energy systems to be constructed (governor of california, ). however, emergency power plant projects permitted under this program were exempt from requirements of the california environmental quality act. additionally, the review process of environmental documents for these projects was allowed to be shortened to days to expedite local permitting. these regulations favor fossil fuel-based power plants compared to renewable energy. on the other hand, as a part of the plan to boost generation capacity, the state of california introduced several additional financial incentives to support the construction of new renewable energy sources, such as tax credits, commercial loan guarantees, and rebates for small renewable energy systems. in addition, the california air resources board established a state emission reduction credit bank to allow peaking power plants to buy emission reduction credits to compensate for increased emissions of nitrogen oxides and particulate matter. the available emission reduction credits are achieved by cleaning up existing facilities that are more polluting, such as older power plants and diesel machinery. the program to increase power generation may have been balanced between fossil fuel-based and renewable energy sources. nevertheless, it is an energy subsidy according to the definition stated in chapter . apart from the plan to increase capacity, the governor of california initiated a series of integrated conservation programs in the amount of $ million that aimed to reduce the demand by % during summer of (state of california, ). the a. ritschel, g.p. smestad / energy policy ( ) – conservation programs consist of public education and outreach, improving energy efficiency in state buildings, load shifting, interruptible service, time-of- use metering, demand buyback programs, and the ‘‘ / ’’ rebate program. the latter provides a % rebate for electricity customers who cut back their electricity use during the summer of by % over the levels in summer of . these conservation initiatives were very effective, and helped california’s electricity consumers to pass the summer of without any blackouts despite a hotter weather than in summer of . the conservation program influenced the energy market significantly and is therefore an energy subsidy according to the definition given previously. the outcome achieved was beneficial both economically and environmentally. it spared californians expensive electricity outages and it reduced emissions connected with the generation of electric power. a drawback of the initiative was, however, that all taxpayers had to pay for parts of the conservation program, including those who have already been energy efficient and who produced their own electricity by distributed energy sources, such as solar panels. a fairer approach would have been to influence the energy consumption behavior of californians not by publicly sponsored media campaigns, but by allowing the utilities to increase their electricity rates. this would have rewarded energy efficient customers and penalized inefficient ones, contrary to a conservation program funded by all taxpayers. . conclusions california’s faulty deregulation plan lead to an electricity market breakdown not often seen in indus- trialized countries. many elements of the original restructuring process (ab ) were fundamentally flawed and led to additional energy subsidies instead of a more deregulated electricity market. regulated retail prices combined with deregulated wholesale prices were a subsidy to electricity consumers that insulated them from market price signals. this discouraged consumers from saving energy or investing in energy efficiency improvements. the result is related to the ‘‘tragedy of the commons’’, where people take excessive advantage of a supposedly free or very inexpensive good thereby depleting, or degrading, it faster. in the case of the california energy situation, high demand, skyrocketing wholesale prices, and electricity shortages were the result. in addition, since utilities could not recover their energy procurement costs, it led to severe financial problems in california’s investor owned utilities. the state of california stepped in by purchasing power in form of long-term power contracts to prevent temporary rate increases to electricity consumers. this action falls under the category of an energy subsidy. alternatively, by letting retail prices float, electricity consumers would have experienced clear price signals and curtailed their demand accordingly. utilities would not have faced insolvency problems, rendering the state’s interventions superfluous. generators would have been paid by utilities for their delivered energy and would have had an incentive to invest in new capacity. higher retail prices would also have stimulated retail competition by facilitating new energy supplier companies to enter into the market. thus, retail price flexibility would have led to reduced demand and increased supply, solving the energy crisis through market forces and opening up the path for a more competitive electricity market, where investments in energy efficiency and renewable energy are rewarded. however, the state interventions to smooth out the impacts of the energy crisis insulated electricity consumers from market realities, supported the existing structure of california’s electricity market, which is predominantly based on fossil fuels, and prevented incentives to improve energy conserva- tion and a switch to renewable energy systems. the mitigation actions by the state of california can therefore be regarded as energy subsidies with both unfavorable economic and environmental conse- quences. acknowledgements the 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finally turning the corner? energy policy ( ), – . state of california, . meeting the energy challenge, how the state of california is taking charge of its energy future. office of the governor, sacramento, ca, june . turn (the utility reform network), . cooking the books. turn, van ness avenue no. , san francisco, ca . tye, w.b., graves, f.c., . the economics of negative barriers to entry: how to recover stranded costs and achieve competition on equal terms in the electric utility industry. natural resources journal ( ), – . van beers, c., de moore, a., . public subsidies and policy failures : how subsidies distort the natural environment, equity, and trade, and how to reform them. edward elgar publishing ltd., glos, uk. a. ritschel, g.p. smestad / energy policy ( ) – 	energy subsidies in california’s electricity market deregulation 	introduction 	california’s deregulation process 	energy subsidies 	defining and measuring energy subsidies 	benefits of subsidy removal 	retail price cap 	recovery of stranded costs 	public benefit programs 	actions undertaken to fix the energy crisis 	power purchases by the state of california 	wholesale price cap 	programs to increase supply and reduce demand for electricity 	conclusions 	acknowledgements 	references microsoft word - .docx www.impactjournals.com/oncoscience oncoscience www.impactjournals.com/oncoscience/ oncoscience , vol. , no. shrewd akt regulation to survive moez dawood, gordon b. mills, zhiyong ding metabolic stress, such as an insufficient supply of nutrients or oxygen owing to inadequate tumor neovascularization, metastasis, or therapy, is a microenvironmental condition frequently encountered by cancer cells [ ]. the ability to survive metabolic stress is thus a necessity for tumor initiation and progression. the serine/threonine kinase akt (also known as protein kinase b) is a primary mediator of survival of both normal and malignant cells [ ]. our recent studies revealed that akt could be differentially activated by site-specific phosphorylation according to the severity and duration of metabolic stress, enabling cells to shift gears to survive [ ]. during canonical akt activation, growth factors or other stimuli activate transmembrane receptor tyrosine kinases, which in turn activate phosphoinositide -kinase to phosphorylate phosphatidylinositol , -bisphosphate to form phosphatidylinositol , , -trisphosphate on the inner cell membrane. akt and its upstream kinase, phosphoinositide-dependent kinase- (pdk ), are recruited to the cell membrane, which initiates akt phosphorylation at thr by pdk [ ]. mammalian target of rapamycin complex and other potential pdk kinases phosphorylate akt at ser , resulting in optimal akt activation [ ]. the active phosphorylated akt then translocates from the cell membrane to other cell compartments to phosphorylate multiple downstream substrates to fulfill its versatile functions. in contrast with canonical akt activation with coordinate phosphorylation on both thr and ser , we identified a novel akt activation mechanism induced by glucose deprivation by which akt is selectively phosphorylated on thr but not ser , resulting in targeting akt to a specific group of substrates [ ]. in hela cells, short-term glucose deprivation (for up to h) induced a modest increase in akt phosphorylation at both thr and ser . in contrast, prolonged glucose deprivation ( h) induced a marked increase in akt phosphorylation at thr (up to -fold) but only a modest increase at ser (twofold to threefold). phosphorylation at thr continued to increase over a -h glucose deprivation period, whereas ser phosphorylation peaked at about h and subsequently declined (figure). apparently, at least two independent processes are responsible for akt phosphorylation during -h glucose deprivation, with a switch occurring between and h. our data indicated that the first process takes place primarily via the release of feedback inhibition from p s k that results in coordinated phosphorylation of akt at both thr and ser . the second process likely occurs via the formation of a complex including grp , pdk , and akt that promotes selective akt phosphorylation at thr . akt is functionally activated by selective thr phosphorylation during prolonged glucose deprivation editorial material figure: akt phosphorylation on thr and ser induced by glucose deprivation and a proposed in vivo metabolic stress model. curves of akt phosphorylation at thr (pt ) and ser (pt ) were generated from previously published data [ ]. the shaded area (“gears shifting”) indicates a proposed stage at which distinct akt activation mechanisms switch. this proposed in vivo metabolic stress model is adapted from a previous publication with modifications [ ]. www.impactjournals.com/oncoscience oncoscience as indicated by increased phosphorylation of several known akt substrates, including glycogen synthase kinase , mammalian target of rapamycin, and y-box binding protein . strikingly, several well-established akt substrates, including pras and bad, were not targeted by akt under glucose deprivation conditions. thus, with selective thr phosphorylation, akt may have altered substrate selectivity. we also observed coordinate phosphorylation of multiple residues other than thr and ser on single akt molecules in an isoform-specific manner [ ], which may also contribute to substrate selectivity. therefore, akt could be shrewdly activated for the right substrate spectrum under different cellular contexts, enabling cells to specifically survive energy crisis during metabolic stress. shrewd akt activation may occur in vivo. when a tumor grows, some tumor cells located away from blood vessels may be subjected to glucose deprivation (figure). we propose that these cells employ a layered defense against cell death according to the severity and duration of metabolic stress. mild or transient metabolic stress (e.g., transient glucose deprivation) induces modest akt phosphorylation at both thr and ser , which provides the first line of defense against cell death. however, during prolonged glucose deprivation, this line of defense becomes insufficient to protect cells against death and is shut off. the next tier of the survival mechanism is then activated. it selectively and markedly increases akt phosphorylation at thr , providing a second line of defense against cell death caused by severe metabolic stress. therefore, cells are capable of shifting gears to survive specific harsh conditions. akt, with its versatile activation mechanisms, provides a set of important survival gears that cells may use under specific conditions. in summary, glucose deprivation induces site- specific phosphorylation and substrate-specific activation of akt via distinct mechanisms according to the duration of metabolic stress. these mechanisms may explain how cells tolerate metabolic stress in tumors by using akt as a survival tool. our findings revealed a novel akt-mediated survival mechanism under prolonged metabolic stress that is important to the development and implementation of drugs targeting cell metabolism and akt signaling. gordon b. mills: department of systems biology, the university of texas md anderson cancer center, houston, tx zhiyong ding: department of systems biology, the university of texas md anderson cancer center, houston, tx correspondence: gordon b. mills, email gmills@mdander- son.org correspondence: zhiyong ding, email zding@mdanderson. org received: march , ; published: march , ; references . hanahan d et al. cell. ; , - . . hennessy bt et al. nat rev drug discov. ; : - . . gao m et al. oncogene. ; : - . . alessi dr et al. curr biol. ; : - . . sarbassov dd et al. science. ; : - . . guo h et al. oncogene. . doi: . /onc. . print huntingtin binds parp elevated par in hd huntingtin binds poly adp ribose dysregulation of poly adp ribose signaling in hd and its potential as a therapeutic target tamara maiuri , carlos barba , rachel j harding , and ray truant department of biochemistry and biomedical sciences, mcmaster university, hamilton, canada structural genomics consortium, university of toronto, toronto, canada berman/topper hd career development fellowship @tam_maiuri raytruantlab.ca maiurit@mcmaster.ca tamara maiuri figure : huntingtin interacts with parylated proteins a. degree of overlap between huntingtin-interacting proteins puri�ed from sthdh cells and a compiled list of parylated proteins from three independently generated databases (gagne et al, ; zhang et al, ; jungmichel et al, ). b. rpe cells were treated with um h o for min and proteins crosslinked with % pfa. huntingtin was immunoprecipitated with epr and associ- ated proteins separated by sds-page and immunoblotted with the indicated antibodies (mabe : par detection reagent). background • dna repair pathways affect hd age at onset (gem-hd consortium, ) • huntingtin acts as a scaffold for dna repair proteins (maiuri et al, ) • poly adp ribose (par) is a post-translational modi�cation generated in response to dna damage huntingtin interactors parylated proteins a b figure : huntingtin par- binding motifs a. huntingtin se- quence analysis revealed �ve motifs matching the par- binding concensus. b. pbm- , , and map to the surface of the huntingtin struc- ture (guo et al, ), while pbm- is not exposed. pbm- is exposed on the c-terminal domain. c. dot blot par overlay assay with full length puri- �ed huntingtin (harding et al, ) (top), hunting- tin fragment - (middle), and pbm peptides (bottom). puri�ed proteins were dotted onto nitrocellulose then overlaid with . um par (trevigen). after washing, anti-par western was per- formed with par detection reagent mabe . a b c figure : huntingtin co-localizes with par rpe cells were treated with um parg inhibitor for min followed by mm kbro for min. soluble proteins were ex- tracted with . % triton x- for min on ice followed by �xation and staining with the indicated antibodies. cells were imaged by super-resolution microscopy (sr-sim). a. par co-localizes with sc -positive nuclear speckles. b. huntingtin co-localizes with par at speckles and redistributes to sites of par production upon oxidative stress. c. co-localization of nuclear signals measured by pearson correlation. n= , cells per condition. a b c figure : huntingtin interacts with poly adp ribose polymerase a. rpe cells were treated with um h o for min and proteins crosslinked with % pfa. huntingtin was immunoprecipitated with epr (abcam) and associated proteins separated by sds-page and im- munoblotted with anti-parp (bd biosciences) and anti-huntingtin (mab , millipore). b. puri�ed huntingtin (harding et al, ) and parp (trevigen) were incubated in the presence of acti- vated dna and nad+. parp was immunoprecipitated with anti-parp antibody (bd biosciences). reactions were separated by sds-page and immunoblotted as in a. background • levels of dna damage are elevated in hd cells and tissues (maiuri et al, ; askeland et al, ; castaldo et al, ) • unrepaired dna damage leads to prolonged activation of parps and overproduction of par • unrelenting par production causes atp depletion, mitochondrial failure and energy crisis • par acts as a mediator of cell death through parthanatos is parp inhibition a viable therapeutic strategy? figure : elevated par levels in hd patient �broblasts truhd immortalized hd patient and control �broblasts (hung et al, ) were pre-treated with μm parg inhibitor for min followed by mm kbro for min. soluble proteins were ex- tracted with . % triton x- for min on ice, followed by �xation and staining with mabe par detection reagent. nuclei were identified as primary objects in cellprofiler (carpenter et al, ) using hoechst staining, then pixel intensity of the par staining within nuclei was calculated and the mean intensity recorded for each image. ten images per well were captured, representing - cells per experiment. the experiment was repeated times for truhd-q q and truhd-q q cells, and four times for truhd-q q cells. p-values were calculated using tukey’s test (****p< . ). more preclinical data needed • parp inhibition is beneficial in hd mouse model (cardinale et al, ; paldino et al, ) • high par levels in hd patient fibroblasts (fig ) • are par levels high in csf from hd patients? • does parp inhibition rescue phenotypes in clinically relevant models? repurposing parp inhibitor drugs • veliparib, niraparib cross the blood brain barrier • risk of genotoxicity, however parp inhibitors are generally protective in postmitotic cells (berger et al, ) references askeland, g. et al., . increased nuclear dna damage precedes mitochondrial dysfunction in peripheral blood mononuclear cells from huntington’s disease patients. scienti�c reports, ( ), p. . berger, n.a. et al., . opportunities for the repurposing of parp inhibitors for the therapy of non-oncological diseases. british journal of pharmacology, ( ), pp. – . cardinale, a. et al., . parp- inhibition is neuroprotective in the r / mouse model of huntington’s disease. plos one, ( ), p.e . carpenter, a.e. et al., . cellpro�ler: image analysis software for identifying and quantifying cell phenotypes. genome biology, ( ), p.r . castaldo, i. et al., . dna damage signatures in peripheral blood cells as biomarkers in prodromal huntington disease. annals of neurology, ( ), pp. – . gagné, j.-p. et al., . proteome-wide identi�cation of poly(adp-ribose) binding proteins and poly(adp-ribose)-associated protein complexes. nucleic acids research, ( ), pp. – . genetic modi�ers of huntington’s disease (gem-hd) consortium, . identi�cation of genetic factors that modify clinical onset of huntington’s disease. cell, ( ), pp. - . guo, q. et al., . the cryo-electron microscopy structure of huntingtin. nature, ( ), pp. – . harding, r.j. et al., . design and characterisation of mutant and wild-type huntingtin proteins produced from a toolkit of scalable eukaryotic expression systems. biorxiv, p. . hung, c.l.-k. et al., . a patient-derived cellular model for huntington’s disease reveals phenotypes at clinically relevant cag lengths. molecular biology of the cell, p.mbce . jungmichel, s. et al., . proteome-wide identi�cation of poly(adp-ribosyl)ation targets in different genotoxic stress responses. molecular cell, ( ), pp. – . maiuri, t. et al., . huntingtin is a scaffolding protein in the atm oxidative dna damage response complex. human molecular genetics, ( ), pp. – . paldino, e. et al., . selective sparing of striatal interneurons after poly (adp-ribose) polymerase inhibition in the r / mouse model of huntington’s disease. frontiers in neuroanatomy, , p. . pleschke, j.m. et al., . poly (adp-ribose) binds to specific domains in dna damage checkpoint proteins. the journal of biological chemistry, ( ), pp. – . zhang, y. et al., . site-speci�c characterization of the asp- and glu-adp-ribosylated proteome. nature methods, ( ), pp. – . parp binding olaparib wikimedia commons diffusion soldering of pb-doped gete thermoelectric modules with cu electrodes using a thin-film sn interlayer c.l. yang, h.j. lai, j.d. hwang, and t.h. chuang , .—institute of materials science and engineering, national taiwan university, taipei , taiwan. .—material and chemical research laboratories, industrial technology research institute, hsinchu , taiwan. .—e-mail: tunghan@ntu.edu.tw directly coating a gete(pb) thermoelectric device with a ni barrier layer and an ag reaction layer and then diffusion soldering with a cu electrode coated with ag and sn leads to breakage at the gete(pb)/ni interface and low bonding strengths of about mpa. an improved process, precoating with lm sn film and heating at �c for min before electroplating with ni and ag layers, results in satisfactory bonding strengths ranging from . mpa to . mpa. the precoated sn film leads to the formation of a (ni,ge) sn layer between the gete(pb) thermoelectric material and ni barrier layer, reducing the thermal stress at the gete(pb)/ni interface. key words: diffusion soldering, gete(pb) thermoelectric modules, intermetallic compounds, bonding strength introduction thermoelectric (te) materials using the seebeck effect or the peltier effect are being developed in response to the energy crisis. the thermoelectric effect, which involves the transfer of heat and elec- tricity, can be applied in power generators, heat dissipators, thermoelectric coolers, and waste heat recovery. however, the thermoelectric conversion efficiency of a single thermoelectric device is limited, so in general, te modules are produced through a combination of multiple te devices bonded with metallic electrodes for commercial applications. traditionally, soldering or brazing methods are employed for the bonding of thermoelectric materials with electrodes. although soldering at lower tem- perature can reduce thermal stress, the bonding interface may melt during subsequent operation of thermoelectric modules at high temperature. braz- ing, on the other hand, allows operation at high temperature because the filler has a higher melting point. unfortunately, while the bonded thermoelec- tric modules are cooling from the high temperature of the brazing process, high thermal stress may occur at the bonding interface. such stress can damage thermoelectric devices. consequently, since soldering and brazing methods both entail the risk of failure in the manufacture or operation of thermoelectric modules, an improved method should be developed. in the alternative method, the thermoelectric mod- ules should be bonded at a temperature as low as possible, and the melting point of the joints should be higher than the working temperature of thermo- electric devices. a novel bonding technique, called diffusion sol- dering, uses the principle of thin-film solid–liquid interdiffusion. this technique might solve the above problems. it employs a low-melting-point metallic thin-film interlayer (lt) that melts at low temper- ature and reacts rapidly with the sandwiched high- melting-point (ht- and ht- ) layers or with the substrates to form intermetallic compounds. the lt layer must be thinner than the ht- and ht- layers or substrates, and the reactions of the lt layer have to be exhausted entirely. this novel technique is suitable for application in emergent high-temperature electronic devices, which demand a low bonding temperature. it has been applied to the manufacturing of microwave packages, high- power devices, thick-film resistors, gaas/si wafer packages, ceramic multichip modules, and even gold jewelry in past decades. recently, diffusion (received june , ; accepted october , ; published online december , ) journal of electronic materials, vol. , no. , doi: . /s - - - � tms estimation and characterization of gaseous pollutant emissions from agricultural crop residue combustion in industrial and household sectors of pakistan lable at sciencedirect atmospheric environment ( ) e contents lists avai atmospheric environment journal homepage: www.elsevier.com/locate/atmosenv estimation and characterization of gaseous pollutant emissions from agricultural crop residue combustion in industrial and household sectors of pakistan muhammad irfan a, muhammad riaz a, muhammad saleem arif a,*, sher muhammad shahzad b, farhan saleem a, naveed-ur -rahman c, leon van den berg d,e, farhat abbas a a department of environmental sciences, government college university faisalabad, faisalabad , pakistan b department of soil & environmental sciences, university college of agriculture, university of sargodha, pakistan c department of environment, health and safety, interloop ltd., faisalabad, pakistan d department of aquatic ecology & environmental biology, faculty of science, radboud university nijmegen, the netherlands e b-ware research centre, nijmegen, the netherlands h i g h l i g h t s � energy crisis has resulted in increased combustion of crop residues in pakistan. � emission attributes of rice husk, rice straw, corncobs and bagasse were estimated. � rice straw had significantly higher gaseous pollutant emission factors. � bagasse had the highest value of total emission of gaseous pollutants. � rice straw and bagasse had > % share in total gaseous pollutant emissions. a r t i c l e i n f o article history: received july received in revised form november accepted november keywords: biomass fuel gaseous pollutants emission factors emission allocations emission inventory * corresponding author. tel.: þ ( ) ; e-mail addresses: msarif@outlook.com, msarif @ - /$ e see front matter � elsevier ltd. http://dx.doi.org/ . /j.atmosenv. . . a b s t r a c t a long-term energy crisis has resulted in increased combustion of biomass fuel in industrial and household sectors in pakistan. we report results of a study on the emission characteristics of rice husk, rice straw, corncobs and bagasse since they are frequently used as biomass fuel and differed remarkably in physico-chemical and combustion characteristics. emission concentrations and emission factors were determined experimentally by burning the biomass fuel using a burning tower. modified combustion efficiency (mce) of rice husk, rice straw, corncobs and bagasse was > . indicating that combustion was dominated by flaming mode. emission factors of gaseous pollutants co, co , no , no, nox and so for rice straw were calculated to be . � . , . � . , . � . , . � . , . � . and . � . g kg� respectively which were significantly (p < . ) higher compared to those from rice husk ( . � . , . � . , . � . , . � . , . � . and . � . g kg� ), corncobs ( . � . , . � . , . � . , . � . , . � . and . � . g kg� ) and bagasse ( . � . , . � . , . � . , . � . , . � . and . � . g kg� ). total emissions of co, co , no , no, nox and so were estimated to be . , . , . , . , . and . gg for rice husk, . , . , . , . , . and . gg for rice straw, . , . , . , . and . gg for corncobs and . , . , . , . , . and . gg for bagasse respectively. rice straw, however, had significantly (p < . ) higher potential of gaseous pollutant emission factors. bagasse had the highest values of total emissions followed by rice straw, rice husk and corncobs. rice straw and bagasse, on cumulative basis, contributed more than % of total emissions of gaseous pollutants. results reported in this study are important in formulating provincial and regional emission budgets of gaseous pollutants from burning of agricultural residues in pakistan. � elsevier ltd. all rights reserved. fax: þ ( ) . yahoo.com (m.s. arif). all rights reserved. mailto:msarif@outlook.com mailto:msarif @yahoo.com http://crossmark.crossref.org/dialog/?doi= . /j.atmosenv. . . &domain=pdf www.sciencedirect.com/science/journal/ http://www.elsevier.com/locate/atmosenv http://dx.doi.org/ . /j.atmosenv. . . http://dx.doi.org/ . /j.atmosenv. . . http://dx.doi.org/ . /j.atmosenv. . . m. irfan et al. / atmospheric environment ( ) e . introduction pakistan, with an annual population growth rate of . % and projected population of million people, has been witnessing severe energy crisis over the last five years. at present, approxi- mately % of energy requirement is met through fossil fuels such as oil and gas, and rest of the energy is obtained from biomass fuel such as wood and agricultural residues (tahir et al., ). crop residues are value added organic byproducts generated from har- vesting and processing of agricultural crops. due to lack of knowledge regarding the significance of crop residues, they are often burned in the field (samra et al., ). agricultural open field burning is widely practiced in the rural areas and suburbs to dispose of biomass waste (yevich and logan, ). several reasons favor burning of crop residue including cleaning and field preparation, meeting domestic energy requirements, fertilizing the field with ash and offering the pest control (huang et al., ; korontzi et al., ). however, the quantity of the crop residues burned and the fire intensity strongly influence the amount of carbon and nutrients released during the fire (sharma and mishra, ). crop residues and/or agricultural wastes are important domes- tic fuels since ancient times. nearly half of the world population utilizes crop residues for domestic heating and cooking, especially in developing countries (guoliang et al., ). according to esti- mates of andreae and merlet ( ) and bond et al. ( ), burning of crop residues accounts for and tg dry matter combustion per year respectively. therefore, air quality deterioration, in cities located around major agricultural sectors, is perhaps not surprising (cancado et al., ). there also have been extensive evidence of overlooking the emissions of trace gases from crop residue burning to a large extent, because these fires are often short-lived and do not offer significant time to be detected and quantified under natural conditions (smith et al., ; vander-werf et al., ). field and domestic burning of crop residues consist of pyrolysis, smoldering and flaming processes, however, dominance of these processes and resultant gas emissions largely depend on the type of material being burnt (andreae and merlet, ). for example, agricultural residues usually follow flaming mode of burning that results in higher nox concentrations, dung cakes are burnt through smoldering mode and burning fuel wood normally pass through all three stages of combustion (saud et al., ). environmental problems associated with crop residue burning include smoke, trace gases and particulate matter (bijay-singh and yadvinder-singh, ). concentrations of the greenhouse gases have increased over the past years as a result of anthropogenic activities including agriculture, and have accelerated the rise in average global temperature (ipcc, ). in particular, uncontrolled and incomplete open-field burning results in emission of toxic air pollutants and greenhouse gases which affect the atmospheric chemistry (andreae and merlet, ; kanabkaew and oanh, ). agricultural crop residue burning is also the prime source of the micron-sized aerosols which affect the composition of atmosphere (awasthi et al., ; saud et al., ). trace gases emitted during burning, carbon monoxide and nitrogen oxide, are the main pre- cursors of tropospheric ozone (o ), decreasing the concentrations of tropospheric hydroxyl radical (oh) (mauzerall et al., ); the later holds potential threats to environment, ecosystem and human health (cheng et al., ). emission factor is a crucial parameter used to estimate and quantify emission of trace gases and aerosols from biomass burning which describes compounds or substances emitted per amount of dry fuel burned (andreae and merlet, ; yang et al., ). emission factors of gaseous pollutants vary with time and space, and also depend on type, quality and composition of biomass fuel (shah et al., ). emission factors, measured over longer time periods, are helpful in making emission inventories to control air pollution at local, national and regional levels. emission factors, from different biomass burning, are integral components for mak- ing emission inventories and budgets. although studies on emissions from biomass burning are well documented across the globe (e.g. delmas and servant, ; lacaux et al., ) including studies of saud et al. ( ) in india and zhang et al. ( ) in china, the research area is yet to be explored in pakistan. it should be noted that there are limited emission factors available in developing countries, and those re- ported in the literature often varied dramatically due to difference in fuel properties and combustion conditions. in addition, emission factors measured in the laboratory may differ from those obtained in field measurements (roden et al., , ; shen et al., ). therefore, there is need to assess emission characteristics of biomass burning in pakistan since sever energy crisis have forced large population to use firewood, crop residues and animal dung for meeting energy demands, especially in rural and peri-urban areas. keeping in context of the above discussion, a field scale study was performed to evaluate the emission characteristics of commonly burned agricultural biomass wastes in pakistan i.e. rice straw, rice husk, corn cobs and bagasse. furthermore, to our knowledge, this is the first study determining emission concentrations, emission fac- tors and emission inventories of trace gases from burning of crop residues in pakistan. the current study was designed to: � investigate the emissions of different gaseous pollutants (co, co , no , no, nox, so ) from burning of rice straw, rice husk, corncobs and bagasse. � characterize and compare the emission factors of rice straw, rice husk, corncobs and bagasse burning � prepare emission inventories to estimate total emissions of trace gases . materials and methods . . selection, sampling and preparation of crop residue samples rice straw, rice husk, corncobs and bagasse were used in this study because they are burnt in the agricultural fields as waste products and in homes and/or industries for energy in pakistan. samples of crop residues were collected in triplicate from farmers’ fields and agricultural processing industry around faisalabad and kasur in punjab, pakistan (fig. ). rice straw and bagasse were collected from gatwala and corncobs were collected from jarran- wala, suburbs of faisalabad. however, rice husk samples were ob- tained from kasur. samples were air dried under outdoor ambient conditions for several days before the start of experiment. when uniformly air-dried, samples were kept in sealed plastic bags. . . construction and design of burning tower for this experiment, a metallic combustion tower was designed with an aim to facilitate the analysis by channelizing the smoke through one stack (fig. ). the tower consisted of an inverted funnel shaped cylindrical bottom having . m diameter and . m height. a stack with internal diameter of . m and length of . m was attached at the top end of the cylindrical bottom (fig. a). the stack was at . m height from the ground. the cylindrical bottom was supported with iron rods to keep it at . m height from ground level (fig. b). a metallic burning table of . m � . m dimension was also constructed using a coarse iron wire-gauze which has . m long legs at its four corners. the stack had an fig. . sampling locations of rice husk, rice straw, corncobs and bagasse in punjab, pakistan. rice husk, rice straw, bagasse, corncobs. m. irfan et al. / atmospheric environment ( ) e opening at . m height from its bottom for insertion of the instrumental probe and recording of different parameters. keeping the burning material on the perforated metallic stand, at . m height, ensured uniform -d movement of gases and ample supply of oxygen to facilitate uniform burning under ambient conditions. . . emission analysis . . . principle of flu gas analyzer trace gas emissions were measured using a digital flu gas analyzer, testo -s (testo ag, germany) by following a modified protocol of li et al. ( ). the analyzer draws gases from the stack with the help of sampling probe. gases pass through the sensors and sensors, based on the principle of selective ion potentiometery, measure the electrochemical potential differences. the range of the instrument for emission concentrations of co was e vol. % whereas range was e , e , e and e ppm for fig. . experimental set up: (a) schemati co, no, no and so respectively. the accuracy of the instrument for co, no, no and so emission concentrations was � % of the measured value. . . . experimental process before each burning test, the selected crop residue was weighed and placed on metallic perforated burning table designed especially to facilitate residue burning (fig. ). after ignition, sampling probe of the analyzer was inserted into the stack to measure trace gas concentrations from the start to the end of each burning cycle of residue combustion at s interval (jenkins et al., ). experimental conditions and design of the combustion tower allowed natural and uniform ventilation during each burning event. time was noted for each burning event and when burning process was completed, ash was collected and weighed to calculate percent mass loss. each crop residue burning test was repeated three times throughout the experiment; however, where c diagram, (b) actual burning tower. fig. . air dried biomass on metallic stand before burring: (a) rice husk, (b) rice straw, (c) bagasse, (d) corn cobs. m. irfan et al. / atmospheric environment ( ) e appropriate, mass weighted means of the data are presented in tables and figures. . . analytical protocols . . . moisture content and mass loss moisture content was measured gravimetrically by drying crop residue samples at �c for h in a pre-heated oven. samples were cooled in a desiccator before they were reweighed and moisture content was calculated on percent dry mass basis. mass loss was calculated by weighing the fuel samples before and after the combustion process was completed (ash content). mass loss was also presented on percent mass basis. . . . total carbon (c), nitrogen (n) and sulfur (s) contents of biomass oven-dried crop residue samples from moisture content deter- mination were further used for the measurements of total c, n and s contents. for c and n analysis, the oven-dried samples were ground using a ball mill (retsch mm ) to homogenize the sam- ples prior to analysis on a carlo erba na cns analyzer (thermo fisher scientific, waltham, ma). c and n content of the samples were calibrated using the standards atropine and acetanilide and an internal reference sample. for s analysis, mg residue ma- terial was digested under high pressure with nitric acid and hydrogen peroxide in sealed teflon vessels using a milestone destruction microwave oven (mls mega). after digestion, the samples were analyzed for s contents on an inductively-coupled plasma emission spectrophotometer (icp, spectroflame flame vml ). standard reference solutions for s were analyzed for cali- bration on icp. c, n and s contents of residue samples were expressed on percent dry mass basis. . . . stack gas velocity, flu temperature, burning cycle and emission concentrations of gaseous pollutants the stack gas velocity (m s� ), flu temperature (�c), burning cycle (s) and emission concentrations of co, co , no , no, nox and so (ppmv) were measured using the digital flu gas analyzer (testo - s). at the start of the burning cycle, the probe of the analyzer was inserted into the stack through the designed hole to record the said parameters for each fuel burning event every s until the burning cycle was complete. emission concentrations were used to calculate emission factors of the gaseous pollutants (guoliang et al., ). . . calculation of emission factors fuel based emission factors of gaseous pollutants represent mass of the specie released per unit fuel weight (andreae and merlet, ). emission factors of gaseous pollutants were calcu- lated using the mass balance equation described by jenkins et al. ( ) and guoliang et al. ( ) and were expressed on g per kg dry weight of the fuel: ei ¼ � mfd ztf t asuci wi : dt ( ) where ei ¼ emission factor for species i mfd ¼ mass of crop residue used in the each burning test t ¼ initial start time for each burning test tf ¼ finishing time for the test as ¼ stack area ( . m ) u ¼ average stack gas velocity ci ¼ sample concentration of species i, and wi ¼ molecular weight of species i . . quantification of crop residue production and burning in pakistan crop residues production was estimated from crop production data (government of pakistan, e ) and relevant residue m. irfan et al. / atmospheric environment ( ) e generation rate or ratio (singh and gu, ) using following relationship: crop residues ðmtÞ ¼ crop production ðmtÞ � crop to residue ratio ( ) total amount of residue burnt, for each residue, was quantified as under: total residue burnt ðmtÞ ¼ total crop residue ðmtÞ � residue dry matter fraction � crop residue burnt ð%Þ ( ) dry matter fraction for each crop residue was obtained from streets et al. ( ) and crop residue percent being burnt was estimated to be % for each crop residue (iqbal and goheer, ). . . estimation of total annual trace gases emissions total annual emission of each gaseous pollutant from burning of biomass fuel was calculated using following relationship described by kanabkaew and oanh ( ) and yang et al. ( ): total annul emissions ¼ m � ef ( ) where, e ¼ total annual emission (gg) m ¼ quantity of crop residues burnt in a year (mt dry mass of residue) ef ¼ emission factors of gaseous species (g kg� fuel dry mass) table moisture content, mass loss, total carbon, total nitrogen and total sulfur content of rice husk, rice straw, corncobs and bagasse. parameter rice husk rice straw corncobs bagasse moisture content (%) . ( . ) a . ( . ) ab . ( . ) a . ( . ) a mass loss (%) . ( . ) c . ( . ) d . ( . ) a . ( . ) b total carbon (%) . ( . ) b . ( . ) b . ( . ) a . ( . ) a total nitrogen (%) . ( . ) bc . ( . ) ab . ( . ) c . ( . ) a total sulfur (%) . ( . ) b . ( . ) a . ( . ) c . ( . ) b values are means of three replicates. standard errors of means are enclosed in parenthesis. in a row, for specified parameter, means with different letters differ significantly from each other at p < . . . . modified combustion efficiency (mce) ward et al. ( ) described combustion efficiency (ce) as the ratio of carbon released as co to the total mass of carbon in the fuel biomass. ce may be considered helpful in determination of the completeness of the combustion as well as indication of process and/or processes dominant during the combustion. ce is usually measured as under: ce ¼ cco =ctotal where cco is the carbon emitted in co form and ctotal is the total amount of carbon in gaseous and particulate emissions. in the current study, cco and cco were measured but particulate matter contents were not measured; hence, the modified combustion ef- ficiency (mce) was calculated following relationship proposed by zhang et al. ( ): mce ¼ cco = � cco þ cco � ( ) . . statistical analysis data regarding moisture content (%), mass loss (%), c (%), n (%), s (%), flu temperature (�c), stack gas velocity (m s� ), burning cycle (s), gaseous pollutant emission concentration (ppmv) and gaseous emission pollutant factors (g kg� ), measured and/or calculated on replicate samples, were subjected to one way analysis of variance (anova). tukey’s hsd postdoc test was used for multiple means comparisons technique only for those parameters where significant treatment effects were found. however, where appropriate, figures and tables contain means of three replicates. . results and discussion . . biomass characteristics physical and chemical characteristics of rice husk, rice straw, corncobs and bagasse are summarized in table . moisture content ranged from . � . % for rice husk to . � . % for bagasse. mass loss percent values were . � . % for rice husk, . � . % for rice straw, . � . % for corncobs and . � . % for bagasse. mass loss percent of corncobs was significantly (p < . ) higher compared to that from rice husk, rice straw and bagasse. c, n and s contents of crop residues are also shown in table . c contents of corncobs and bagasse were . � . and . � . % respectively which were significantly (p < . ) higher than c content of rice husk ( . � . %) and rice straw ( . � . %). n contents were . � . % for rice husk, . � . % for rice straw, . � . % for corncobs and . � . % for bagasse. s contents of rice straw, . � . %, were the highest among the crop residue used in this study and were significantly (p < . ) different from rice husk, corncobs and bagasse. the moisture content, mass loss, c, n and s contents of biomass fuel have a significant impact on the burning and emission char- acteristics of biomass. in our study, bagasse had the highest mois- ture contents compared to rice husk, rice straw and corncobs. the moisture content of rice straw ( . %) was in accordance with the range of moisture content ( e %) for rice straw previously re- ported by buzarovska et al. ( ). however, the moisture content of the rice husk was higher compared to that . % observed by ileleji and zhou ( ). this higher moisture content of rice husk could be attributed to regional climatic conditions. the results of mass oxidized (mass loss) for bagasse was similar to those reported by sahai et al. ( ). however, mass loss values for rice straw, rice husk and corncobs was found to be . , . and . % which differed slightly from the reported % value of mass loss for these crop residues (sahai et al., ). in this study, we have also re- ported c, n and s contents of crop residues since the chemical composition of the crop residue is an important factor in deter- mining the emission factors of gaseous pollutants as argued by zhang et al. ( ). . . burning characteristics flu temperature, stack gas velocity, burning cycle and modified combustion efficiency (mce) for rice husk, rice straw, corncobs and bagasse are presented in table . flu temperatures of rice straw m. irfan et al. / atmospheric environment ( ) e ( . � . �c) and bagasse ( . � . �c) were significantly higher (p < . ) compared to that for rice husk ( � . �c) and corncobs ( . � . �c). values of stack gas velocity were . � . , . � . , . � . and . � . m s� for rice husk, rice straw, corncobs and bagasse respectively. bagasse had significantly (p < . ) higher stack gas velocity values compared to rice husk, rice straw and corncobs. there were sig- nificant (p < . ) differences in length of burning cycle for rice husk, rice straw, corn cobs and bagasse. mce ranged from . for rice husk and rice straw to . for bagasse. bagasse had signifi- cantly (p < . ) higher mce compared to rice husk, rice straw and corncobs. in this study, stack gas velocity was measured under ambient conditions since it determines speed of gaseous pollutant emis- sions from open burning of residue biomass and depends on the ambient environmental conditions like air flow to ensure optimum oxygen concentrations for complete and efficient burning (wardoyo et al., ). bagasse showed the highest value of stack gas velocity in this study. burning cycle could also serve as important determinant of combustion efficiency of biomass and depends on physical and chemical characteristics of fuel biomass (ward et al., ). mce was measured to distinguish between flaming and smoldering mode of combustion during crop residue burning. mce in our study was . , . , . and . for rice husk, rice straw, corncobs and bagasse respectively which falls in the range of . e . suggested by reid et al. ( ) for fires following flaming as dominant mode of combustions. however, it is also an established fact that smoldering and flaming mode of combustions cannot be separated completely when biomass is burnt under field conditions. nevertheless, mce of crop residues in our study support the well-documented claim that agricultural crop residue burn under flaming mode under field and laboratory conditions (saud et al., ; zhang et al., ). . . emission factors of gaseous pollutants emission factors (efs) of gaseous pollutants, calculated from emission concentrations, of rice husk, rice straw, corncobs and bagasse are shown in fig. . the mean emission factors of co for rice husk, rice straw, corncobs and bagasse were . � . , . � . , . � . and . � . g kg� respectively (fig. a). emission factor of co of rice straw were significantly (p < . ) higher compared to rice husk, corncobs and bagasse. emission factors of co from rice husk ( . � . g kg� ), rice straw ( . � . g kg� ), corncobs ( . � . g kg� ) and bagasse ( . � . g kg� ) followed order similar to that of co emission factors (fig. b). emissions factors of no were . � . , . � . , . � . and . � . g kg� for rice husk, rice straw, corncobs and bagasse respectively (fig. c). emission factors of no from rice straw were significantly (p < . ) higher compared to that from rice husk, rice straw, corncobs and bagasse. emission factors of no from rich husk, rice straw and bagasse were . � . , . � . and table flu temperature, stack gas velocity, burning cycle and modified combustion effic parameter rice husk rice st flu temperature (�c) ( . ) c . stack cas velocity (m s� ) . ( . ) c . burning cycle (s) . ( . ) b modified combustion efficiency (mce) . ( . ) a . values are means of three replicates. standard errors of means are enclosed in par significantly from each other at p < . . . � . g kg� respectively (fig. d); they were significantly (p < . ) higher from no emission factors of corncobs ( . � . g kg� ). emission factors of nox ranged from . � . g kg� for corncobs to . � . g kg� for rice straw (fig. e). emission factors of so were . � . , . � . , . � . and . � . g kg� from burning of rice husk, rice straw, corncobs and bagasse respectively (fig. f). emission factors of so from rice straw were found to be highest and significantly (p < . ) different from rice husk, corncobs and bagasse. emission factor is an important tool to estimate total gaseous pollutant emissions to help making pollution inventories and pol- icy decision to mitigate air pollution (van leeuwen and hermens, ; andreae and merlet, ; yang et al., ). emission fac- tors for different crop residues have been widely reported in liter- ature, especially of rice straw. the rice straw produced the highest emission factors of the trace gases in the current study. the emis- sion factors of co, co , no , no, nox and so from rice straw were calculated to be . � . , . � . , . � . , . � . , . � . and . � . g kg� respectively which showed considerable agreement with data of some previous studies on rice straw e.g. emission factors of co g kg � (smith et al., ), nox . g kg � (guoliang et al., ) and no . g kg � (zhang et al., ). however, emission factors of co and so were found to be different than those reported in literature e.g. jenkins et al. ( ) reported . and . g kg� emission factors of co and so respectively which were higher than those reported in our study. the emission factors of co, co , no , no, nox and so from bagasse were . � . , . � . , . � . , . � . , . � . , and . � . g kg� respectively. emission factors of nox and no for bagasse from this study were comparable to . g kg� nox (dennis et al., ) and . g kg � no (brocard et al., ). however, emission factors of co, co , no and so from bagasse were lower from those previously reported e.g. co . g kg� and co g kg � (kanabkaew and oanh, ), no . g kg� (brocard et al., ), so . g kg � (kato, ) and . g kg� (gadi et al., ). these differences in emission factors could be due to factors like moisture content and local climatic conditions (goldammer et al., ), physical and chemical differ- ences in the crop residue composition of different regions (lobert and warnatz, ) and, especially n contents for the variations in nox emission factors (zhang et al., ). the emission factors from corncobs and rice husk have not widely been reported in the literature and this is perhaps the first attempt in this regard. the emission factors of co, co , no , no, nox and so from burning of corncobs were observed to be . � . , . � . , . � . , . � . , . � . and . � . g kg� respectively. the results of emission factors of so and nox were in reasonable agreement with . g kg � for so by cao et al. ( ) and . g kg� for nox by zhang et al. ( ) which were based on the burning of aggregated maize crop waste. however, the emission factors of co and co from our study for corncobs differed from those reported by andreae and merlet ( ) for co ( g kg� ) and zhang et al. ( ) for co iency (mce) of rice husk, rice straw, corncobs and bagasse. raw corncobs bagasse ( . ) a . ( . ) b . ( . ) a ( . ) b . ( . ) b . ( . ) a ( . ) a . ( . ) d . ( . ) c ( . ) a . ( . ) b . ( . ) c enthesis. in a row, for specified parameter, means with different letters differ rice husk rice straw corncobs bagasse c o ( g k g - ) a b a c d rice husk rice straw corncobs bagasse c o ( g k g - ) b b a b c rice husk rice straw corncobs bagasse n o ( g k g - ) . . . . . . c a b c c rice husk rice straw corncobs bagasse n o ( g k g - ) . . . . . . . . . d a a a b rice husk rice straw corncobs bagasse n o x ( g k g - ) . . . . . . . . e a b c d rice husk rice straw corncobs bagasse s o ( g k g - ) . . . . . . f a b b c fig. . gaseous pollutant emission factors from burning of rice husk, rice straw, corncobs and bagasse: (a) co, (b) co , (c) so , (d) nox, (e) no , (f) no (units: g kg � ). values are average of three replicates. error bars are standard error of means (n ¼ ). bars with different letters differ significantly from each other at p < . . table estimation of production of rice straw, rice husk, bagasse and corncobs in pakistan in e . residue type crop production (mt)a crop to residue ratiob total crop residue production (mt)c rice husk . rice straw . corncobs . bagasse , . , a government of pakistan ( e ). b singh and gu ( ). c metric tons. m. irfan et al. / atmospheric environment ( ) e ( g kg� ). this difference could be due to the reason that they measured emission factors by burning aggregate maize crop res- idue; however, in contrast, we used corncobs which could result in different emission factors through changes in the composition of biomass (lobert and warnatz, ). the emission factors of co, co , no , no, nox and so from burning of rice husk were . � . , . � . , . � . , . � . , . � . and . � . g kg� respectively. the results suggested considerable differences in emission factors of rice straw and rice husk due to the very fact that they were sampled from different locations. . . emission estimates, inventories and allocation of gaseous pollutants rice husk, rice straw, corncobs and bagasse are important res- idue producing crops being used as biomass fuel in pakistan. in order to prepare emission estimates, inventories and allocations, quantity of crop residues was estimated to be , , and mt for rice husk, rice straw, corncobs and bagasse respec- tively (table ). based on the dry matter fraction (streets et al., ) and percent of the crop residues being combusted ( %; iqbal and goheer, ), total crop residue burned for rice husk, rice straw, corncobs and bagasse was found to be , , and mt respectively (table ). bagasse had the highest values for residue production and combustion followed by rice straw, rice husk and corncobs respectively. total emissions (gg) from crop residues for co, co , no , no, nox and so are presented in table . total emissions from bagasse were . , . , . , . , . and . gg for co, co , no , table estimation of residue burnt in pakistan in e . residue type total crop residue (mt) dry matter fractiona crop residue/dry matter burnt (%)b total residue burnt (mt)c rice husk . rice straw . corncobs . bagasse , . a streets et al. ( ). b iqbal and goheer ( ). c metric tonns. m. irfan et al. / atmospheric environment ( ) e no, nox and so respectively. total emissions from bagasse for co, co , no and nox were the highest compared to those from rice straw, rice husk and corncobs. however, total emissions of no ( . gg) and so ( . gg) from the rice straw were found to be highest compare to the other crop residues (table ). total emis- sions for each gaseous pollutant from burning of crop residue were . gg for co, . gg for co , . gg for no , . gg for no, . gg for nox and . gg for so . calculated from table , emission allocations for gaseous pollutants from rice husk and bagasse together accounted for . , . , . , . , . and . % total emission of co, co , no , no, nox and so . our study also showed that the cumulative contribution of rice husk and corncobs to the total emissions of gaseous pollutants was marginal. total emissions of gaseous pollutants from burning of rice husk, rice straw, corncobs and bagasse were many fold lowered compared to those reported in studies from china (zhang et al., ) and india (saud et al., ). however, china and india are the largest countries of the world with remarkably higher agri- cultural crop production and crop residue generation. we esti- mated total emissions of gaseous pollutants considering burning of only % crop residue as is the case in china suggested by gao et al. ( ) and iqbal and goheer ( ); however, recent energy crisis in pakistan has led to far higher utilization of crop residues as biofuel which may mean that actual total emission could be higher. we have observed that bagasse contributed largely to the budgets of gaseous pollutants especially of co, co and nox in pakistan. this could be related to the considerably higher emission factors and the most importantly, larger amounts of bagasse production as compared to rice straw, rice husk and corncobs. the rice straw and the bagasse contributed more than % of total emission of gaseous pollutants. field burning of rice husk, rice straw, corncobs and bagasse is not commonly practiced in pakistan; however, these crop residue are largely consumed in industrial and rural sectors. in addition, household income of large percent of farmers in pakistan is low whereas energy supply and cost is becoming expensive so they usually opt to use crop residues to meet domestic energy re- quirements. the latter claim is supported by studies of cao et al. ( ) and chen ( ) who found that field burning of crop res- idues was related to income level of farmers. table estimation of total gaseous pollutant emissions (gg) from the crop residue burning in pakistan in e . residue type total emissions (gg)a co co no no nox so rice husk . . . . . . rice straw . . . . . . corncobs . . . . . . bagasse . . . . . . total . . . . . . a gg ¼ � g. we have reported emission factors and total emissions from combustion of crop residues which are commonly used in indus- trial and household sectors of pakistan. according to best of our knowledge, this is the first study reporting emission inventories of gaseous pollutants from burning of agricultural residues. results described in the study are assumed to be helpful in making national and provincial estimates of gaseous pollutants from frequently consumed agricultural residue biomass. however, it should be noted that variations in fuel properties and combustion conditions could lead to rather rough estimates of emission factors with high degree of uncertainty. . conclusions and future research recent energy crisis has led to increased dependency on agriculture-based biomass fuel combustion in agro-industrial and household sectors in pakistan. rice husk, rice straw, corncobs and bagasse represent common biomass fuels in pakistan. biomass fuels differed markedly for physical, chemical and combustion charac- teristics. modified combustion efficiency (mce) ranged from . to . indicating flaming as the mode of combustion under ambient conditions. this study reports experimentally measured gaseous pollutant emission concentrations, emission factors and emission inventories of rice husk, rice straw, corncobs and bagasse combusted under ambient outdoor conditions using specially designed burning tower. emission factors of co, co , no , no, nox and so were determined to be . � . , . � . , . � . , . � . , . � . and . � . g kg� for rice husk, . � . , . � . , . � . , . � . , . � . and . � . g kg� for rice straw, . � . , . � . , . � . , . � . , . � . and . � . g kg� for corncobs and . � . , . � . , . � . , . � . , . � . and . � . g kg� for bagasse. results of emission factors of gaseous pollutants from burning of rice husk, rice straw, corncobs and bagasse were in reasonable agreement with those reported elsewhere. total emis- sions of co, co , no , no, nox and so from burning of biomass fuels were estimated to be . , . , . , . , . and . gg respectively. on cumulative basis, rice straw and bagasse contributed more than % of total emissions of gaseous pollutants. results of this study are important in formulating provincial and regional budgets of gaseous pollutants from burning of agricultural residues. however, biomass fuels like cotton sticks and dung cake needs to be assessed for their role in emission of gaseous pollutants in future since they also represent important biofuels in rural sec- tors of pakistan. appendix a. supplementary data supplementary data related to this article can be found at http:// dx.doi.org/ . /j.atmosenv. . . references andreae, m.o., merlet, p., . emission of trace gases and aerosols from biomass burning. glob. biogeochem. cycles , e . awasthi, a., agarwal, r., singh, n., gupta, p.k., mittal, s.k., . study of size and mass distribution of particulate matter due to crop residue burning with sea- sonal variation in rural area of punjab, india. j. environ. monitor. , e . bijay-singh, yadvinder-singh, . environmental implications of nutrient use and crop management in rice-based ecosystems. in: mew, t.w., brar, d.s., peng, s., dawe, d., hardy, b. 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( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref 	estimation and characterization of gaseous pollutant emissions from agricultural crop residue combustion in industrial and ... 	 introduction 	 materials and methods 	 . selection, sampling and preparation of crop residue samples 	 . construction and design of burning tower 	 . emission analysis 	 . . principle of flu gas analyzer 	 . . experimental process 	 . analytical protocols 	 . . moisture content and mass loss 	 . . total carbon (c), nitrogen (n) and sulfur (s) contents of biomass 	 . . stack gas velocity, flu temperature, burning cycle and emission concentrations of gaseous pollutants 	 . calculation of emission factors 	 . quantification of crop residue production and burning in pakistan 	 . estimation of total annual trace gases emissions 	 . modified combustion efficiency (mce) 	 . statistical analysis 	 results and discussion 	 . biomass characteristics 	 . burning characteristics 	 . emission factors of gaseous pollutants 	 . emission estimates, inventories and allocation of gaseous pollutants 	 conclusions and future research 	appendix a supplementary data 	references generation of wind power using helical structured blades by the concept of “wind tree novateur publications international journal of research publications in engineering and technology [ijrpet] issn: - volume , issue , march- | p a g e generation of wind power using helical structured blades by the concept of “wind tree” vivek r. raut department of electrical, dbacer, nagpur, india, vivekrautphw@gmail.com sayli s. dhande department of electrical, dbacer, nagpur, india, sayli.dhande @gmail.com rohit h. jambhulkar department of electrical, dbacer, nagpur, india, rohitjam @gmail.com abstract: power requirements of the world are ever increasing. in order to fulfill these, it is essential to discover new energy sources or rather improvise the existing techniques for extracting maximum energy. the wind tree is a concept that uses a helical blade (vawt) for generation of electric power. the helical blade is omni-directional which means it is capable of rotating irrespective of the wind flow. the project aims at generating electricity by means of small wafts of air that circulate around the buildings and streets. despite of the wind being fluctuating in nature; the turbine is capable of generating electricity, as a small waft of air is sufficient to rotate this turbine. keywords: wind turbine, helical blades, omni- directional, vawt, generation. i. introduction: wind is considered as the fastest growing clean energy source which is readily available. the concept of wind tree is unique in itself the turbines are sculpted in the form of an artificial tree. it aims at utilizing the low winds that circulate around buildings and streets. the artificial aeroleafs serving as microturbines spin on a vertical axis and is capable of harnessing more gentle winds. the turbine being small and light in weight are set in motion by winds as light as . miles/hr. the betz’s law calculates the maximum power that can be extracted from the wind, independent of the design of a wind turbine. according to betz’s law, no turbine can capture more than . % of the kinetic energy in wind. bets law explains that power extracted from wind energy is directly proportional to the cube of wind velocity. figure . global wind data betz’s law: before you begin to format your paper, according to betz's law, no turbine can capture more than / ( . %) of the kinetic energy in wind. the factor / ( . ) is known as betz's coefficient. practical utility-scale wind turbines achieve at peak % to % of the betz limit. the betz limit is based on an open disk actuator. if a diffuser is used to collect additional wind flow and direct it through the turbine, more energy can be extracted, but the limit still applies to the cross-section of the entire structure. the power of the wind is proportional to air density, area of the segment of wind being considered, and the natural wind speed. the relationships between the above variables are provided in equation, pw = ½ρau . figure . betz’s law ii. background study: the idea of creating an electrical power generating system in the form of a tree, with each leaf as an actual mini wind turbine. capturing low wind speeds and turbulence is at the crux of this novel approach which can deliver power and autonomy simply through a proliferation of leaves. it is the first human-scale biomimetic wind turbine capable of recreating a sympathetic bond between the consumer and their means of power generation. mailto:vivekrautphw@gmail.com mailto:sayli.dhande @gmail.com mailto:rohitjam @gmail.com novateur publications international journal of research publications in engineering and technology [ijrpet] issn: - volume , issue , march- | p a g e iii. system block diagram: : iv. helical blades: figure . helical blades views v. dc generator: figure . dc series generator vi. control unit: control unit helps to store electrical energy by charging the battery as well as supplying power to load using the wind energy thus resulting in maximum wind power utilization during charging mode. control unit checks for the main generated voltage and the battery voltage. if generation is on, supply is directed to battery and it is charged. if generation is off, then battery is charged using wind tree in case of no main supply, load is switched on, which uses the voltage from battery. the battery voltage is checked continuously and shown in display. if it goes less than a v battery indication is shown and the load is turned off. the control circuits is a microcontroller kit programmed in embedded c. the control circuit consists of ldr, so that the lighting load will be switched off during day and the ldr is connected to relay to trip the load from battery. figure . control circuit pin diagram vii. system working: the design of wind tree is capable of extracting maximum kinetic energy from the wind owing to the structured blade design. the helical structured blades are used for this purpose wherein the blades are positioned vertically or transverse to the axis of rotation. these turbines are independent of the direction of fluid flow, thus making it possible for them to rotate even at low velocity of air. the helical structured blade is considered the most efficient owing to its unique design and a lighter weight enabling a smooth flow of air throughout. the unique blade design rotates the turbine even by small wafts of air. a gearbox is attached between the blade and generator in order to increase the number of rotations and enables the system to work smoothly. a coreless dc generator having rated output of - v and maximum speed of rpm is used that has good efficiency even at low rotations. a buck boost converter is connected to the dc generator which helps in providing a regulated dc output voltage from either and ac or a dc output voltage. a battery is used to store the generated power. a charge controller is connected to the battery in order to protect it from over charging and to stop the reverse flow of current. a suitable load is attached to the battery in case of overcharging. specifications: type: coreless rated output voltage: v- v dc. maximum speed: rpm. rated torque: . n-m. noiseless. novateur publications international journal of research publications in engineering and technology [ijrpet] issn: - volume , issue , march- | p a g e viii. proposed design of system: ix. system prototype: acknowledgment: we would like to take this opportunity to acknowledge the invaluable guidance, enormous assistance and excellent co-operation extended to us from each and every corner for proceeding smoothly in this project. we express our most sincere gratitude to our guide and project coordinator prof. s. a. kale and co- guide mr. a. v. kakde for being our constant source of help and inspiration throughout the work.. we are grateful to dr. b. s. umre for his suggestions. and all faculties who have helped us throughout. conclusions: hence we have come to the conclusion that there is still a lot of scope of energy production with the help of wind turbines. with better design and increasing the number of turbines along with some advanced technology it is possible to implement this project on a large scale. it would not only solve the problem of energy crisis to a great extent but would also give a landscape view to the city. we highly recommend these wind trees alongside the streets in order to save electricity required for the street load. by further increasing the height and the number of turbines, it is possible to light up an entire building with the help of these wind trees. even though the wind being fluctuating in nature, it is constantly available * which makes it a more reliable option than the solar panels. the test result obtained ranged between - v, and can be improved by précised design of areoleafs. references: ) a simulation study onairfoilsusing vawt design for low wind speed application. ) peter l franenkel: “applications for winds systems in developing countries. ” novateur publications international journal of research publications in engineering and technology [ijrpet] issn: - volume , issue , march- | p a g e ) sathyanarayana, r;muthamizh, s ; giriramprasath, c,; gopinath, k. t. communication software and networks (iccsn), ieee rd international conference on digital object identifier: . / iccsn. . publication year: ) gipe, paul, . “wind power,” chelsea green publishing company, page ) johnson, dr. gary l. (november , ) “wind turbine power – ch . wind turbine power, energy and torque.” retrieved from http:// www.eece. ksu.edu/ ~gjohnson /wind .pdf in october . ) g.r. nagpal, tool engineer & design (khanna publishers) th’ reprint. ) h. g. patil, design data handbook (pooja publications). ) noguchi. t., windmill for wind power generation, us patent , , , . ) renewable energy world, sept-oct , vol- . ) small wind turbine design notes. ) energy management strategy for parallel connected esss in dc micro grids with renewable energy generation. y.c. fong* j. hu k.w.e. cheng power electronics research centre, department of electrical engineering , the hong kong polytechnic university/ hung hom, kowloon, hong kong. http://www.eece/ 	i. introduction: 	ii. background study: 	acknowledgment: 	references: concussion ( ) cnc eissn - . /cnc- - © philip john ainsley dean cnc concussion review there is significant overlap between the neuropathology of mild traumatic brain injury (mtbi) and the cellular role of creatine, as well as evidence of neural creatine alterations after mtbi. creatine supplementation has not been researched in mtbi, but shows some potential as a neuroprotective when administered prior to or after tbi. consistent with creatine’s cellular role, supplementation reduced neuronal damage, protected against the effects of cellular energy crisis and improved cognitive and somatic symptoms. a variety of factors influencing the efficacy of creatine supplementation are highlighted, as well as avenues for future research into the potential of supplementation as an intervention for mtbi. in particular, the slow neural uptake of creatine may mean that greater effects are achieved by pre-emptive supplementation in at-risk groups. first draft submitted: september ; accepted for publication: february ; published online: march keywords:  behavioral symptoms • brain injury • clinical outcome • concussion • creatine  • magnetic resonance spectroscopy • mild tbi • neurobiology • neuroprotection  • postconcussion syndrome • treatment creatine supplementation has been predom- inately used for peripheral enhancement, increasing muscle function and strength in an athletic environment [ ] and in those with impaired movement [ , ]. however, this mol- ecule has also begun to be investigated for its use in cognitive enhancement in nonclinical groups [ ], and as a potential neuroprotective supplement to reduce damage and alleviate symptoms in those with neurological disor- ders [ , , ] and brain injury [ , ]. the interest in both muscular and neural supplementa- tion comes from its predominant role in energy homeostasis in high or fluctuating energy demand tissues such as muscles and brain [ ]. increasing the creatine stores in the brain could therefore aid in neurodevel- opmental, psychiatric and acquired injury- based disorders where there is evidence of dysfunctional energy processing or altered creatine. this review investigates the potential for creatine supplementation following mild trau- matic brain injury (mtbi), as well as potential neuroprotective effects if taken prior to injury. first, the case for a role of creatine in mtbi will be discussed, looking at overlap in biology and symptom report as well as alterations in neural creatine after mtbi. studies investigating the effects of creatine supplementation after trau- matic brain injury (tbi) will then be summa- rized, along with its effect in nonclinical and related clinical groups. finally, the factors to consider for creatine supplementation, such as neural uptake, timing, dosing, i ndividual effects and safety issues, will be presented. the case for a role of creatine in mtbi overlap in biology tbi induces both focal damage, where the brain impacts the skull, and more diffuse dis- potential for use of creatine supplementation following mild traumatic brain injury philip john ainsley dean*, , gozdem arikan , bertram opitz & annette sterr school of psychology, faculty of health  and medical sciences,  university of surrey, guildford, surrey,  gu   xh, uk *author for correspondence:  p.dean@surrey.ac.uk review part of for reprint orders, please contact: reprints@futuremedicine.com . /cnc- - concussion ( ) cnc future science groupfuture science group review dean, arikan, opitz & sterr ruption in neural function. focal injury is associated with vascular damage in cortical gray matter areas, which can lead to secondary damage around the site of impact due to ischemia, glutamate neurotoxicity, breakdown of the blood–brain barrier (bbb), edema and neuroinflammation [ , ]. the role of neuroinflam- mation after tbi may be beneficial as well as damag- ing, depending on the time period and circumstances, and is still an active area of research [ ]. large-scale focal injury is uncommon after mtbi, but there is evidence for vascular changes (reduced cerebral blood flow and capillary number) and similarities in the met- abolic cascade that leads to secondary damage such as edema and neuroinflammation [ , ]. the primary mechanism for damage in mtbi is thought to be the diffuse stretching of axons by inter- nal shear and strain forces (traumatic axonal injury [tai]) [ , ]. these forces are unlikely to cause immediate axonal disconnection or swelling [ ], and instead induce secondary damage via a metabolic cascade [ – ] of neu- rochemical, metabolic and inflammatory changes [ – ]. this cascade may ultimately result in delayed axonal dis- connection and swelling or even cell death, but it is more probable that axons will remain intact but functionally impaired, with altered conduction velocities [ ]. in brief, the metabolic cascade [ – ] starts when the diffuse stretching of axons makes membranes more permeable and allows an ionic flux, whereby there is an increase in intracellular calcium and sodium as well as extracellular potassium. this leads to nonspecific membrane depolarization, which in turn triggers volt- age or ligand-gated ion channels and an indiscriminate release of excitatory neurotransmitters such as glutamate. these neurotransmitters bind to synaptic receptors to instigate further depolarization and cause a feedback loop resulting in a ‘spreading-depression’-like state (see figure a) [ ]. depolarized neurons use atp-dependent ionic pumps to try and regain resting membrane poten- tial, with replenishment of neuronal atp stores requiring increased oxidative respiration and glycolysis. however, cerebral oxidative respiration is compromised by vascular changes during mtbi (reduced blood flow and impaired autoregulation) [ ], and impaired mitochondrial func- tion (due to increased intracellular calcium) [ ]. anaero- bic glycolysis is increased, resulting in raised intracellular lactic acid, but may not be sufficient to provide the extra energy required. this process therefore results in a gener- alized cellular energy crisis (see figure b) [ ], with meta- bolic dysfunction potentially lasting for days or weeks after injury [ , ]. part of the reason for more long-term metabolic alter- ations could be due to the secondary effects of impaired mitochondrial function and increased intracellular cal- cium. mitochondria sequester some of the intracellular calcium, but this impairs their ability to perform oxida- tive respiration efficiently and results in the production of damaging free radicals and reactive oxygen species (ros) [ , , ]. these induce oxidative stress, causing lipid peroxidation, cytoskeleton damage and perhaps even inflammatory changes [ , , , ]. furthermore, the altered metabolic environment within mitochon- dria (increased calcium, oxidative stress, reduced atp) can lead to the formation of mitochondrial permeabil- ity transition pores (mptp), which can in turn release proteins that induce cell death (apoptosis) [ ]. increased intracellular calcium not only impairs mitochondrial function, but also activates enzymes that degrade ion channels to make them more porous (increasing ionic flux), breakdown axonal structures such as the cytoskel- eton and microtubules (impairing axonal transport), and potentially lead to axonal disconnection and even apop- tosis (see figure c) [ , ]. finally, alterations in neuro- transmission have been reported after injury [ , , ], particularly in the cholinergic and catecholaminergic (dopamine/adrenergic) systems. there is also evidence of altered gaba neurotransmission after injury, with reduction perhaps altering the inhibitory-excitatory n eurotransmission balance after injury [ ]. creatine (methylguanidoacetic acid) is a naturally occurring nitrogenous organic acid, stored predomi- nately in skeletal muscles [ , ] but also present in the liver, kidney, testes and brain [ ]. the predominant role of creatine (cr) is to maintain energy homeostasis by keeping cellular atp levels constant in cells with high and fluctuating energy demands, such as those found in muscles and the brain [ , , ]. it is in this role that the overlap with mtbi neuropathology is most apparent, as the cellular energy crisis induced by mtbi places an extremely large demand on atp in an e nvironment of reduced blood flow and hypoxia. creatine kinase (ck) enzymes within the mitochon- dria (umt-ck) transfer the energy stored in atp to cr by transferring the phosphate group to create phospho- creatine (pcr) and adp (see figure b). in times of low energy demand, mitochondria use oxidative respiration to create atp, with some of this energy locked away or ‘stored’ as pcr. in times of high energy demand, a ck in the cytosol (bb-ck) can regenerate atp from these pcr stores as required. as pcr is smaller and less nega- tively charged than atp, it is able to move more freely through the cell [ ], diffusing quickly between the site of atp production (mitochondria) and use (e.g., syn- apse) [ ], where it is able to be stored in large amounts for future use [ ]. this cr/pcr/ck mechanism means that levels of atp can remain constant even when the energy demand increases by several orders of magni- tude (‘the stability paradox’ [ ]), by both regenerating at site of use from local pcr stores (‘temporal energy www.futuremedicine.com . /cnc- - www.futuremedicine.com future science groupfuture science group creatine supplementation following mtbi review future science group buffer’), and quickly shuttling newly created pcr from mitochondria to the site of use (‘spatial energy buf- fer’) [ , , ]. indeed, it is so efficient in this role that atp levels remain stable until quite severe levels of oxygen depletion [ ]. critically for the case of mtbi, the creatine system enables cells to regenerate atp quickly, efficiently and without the need for oxygen. all of these prop- erties would help reduce the generalized energy crisis seen after mtbi, where atp is in high demand for restoration of membrane potentials and ion gradients (e.g., calcium), neurotransmitter release and reuptake, and intracellular transport [ , , ]. in addition, the tight coupling of the creatine system and atp produc- tion in mitochondria has other benefits effects on the energy status of the cell, which are relevant to mtbi neuropathology. as the phosphate from atp is trans- ferred to pcr, this increases adp levels in the mito- chondria, which stimulates respiration and reduces the energy required for atp synthesis [ , , ]. increased use of pcr to generate atp, and increased mitochondrial efficiency reduces the amount of glycolysis required, and thus the amount of lactic acid accumulation [ , ]. in addition to beneficial effects on cell energy status, creatine has a role in the secondary mechanisms related to mitochondrial dysfunction and increased calcium homeostasis observed after mtbi. the tight coupling of creatine and atp in mitochondria may also reduce the likelihood of the formation of ros, thereby hav- ing an antioxidant effect [ , , , ]. it is also thought that creatine may have a more direct antioxidant role as a scavenger of free radicals and reactive species [ , ]. regeneration of atp and reduction of free inorganic phosphate by bb-ck aids in calcium homeostasis [ ] (figure c), decreasing both intracellular and mito- chondrial calcium. furthermore, creatine reduces the figure . the neurometabolic cascade after mtbi, and its overlap with creatine biology (in red). (a) how diffuse injury after mtbi results in large-scale membrane depolarisation (a ‘spreading depression’-like state), reduced blood flow and increased intracellular calcium. (b) the generalised cellular energy crisis, where large amounts of atp are required to repolarise the membranes and counteract the ‘spreading depression’-like state. this occurs in a low oxygen environment, with dysfunctional mitochondria (due to calcium sequestering), resulting in increased glycolysis and lactic acid formation, along with increased oxidative stress and potential formation of mptp. (c) the secondary effects of increased intracellular calcium. red boxes and arrows indicate the role and influence of creatine within mtbi neuropathology. adp: adenosine di-phosphate; atp: adenosine tri-phosphate; bb-ck: braincreatine kinase; cr: creatine; mptp: mitochondrial permeability transition pore; mtbi: mild traumatic brain injury; pcr: phosphocreatine; ros: reactive oxygen species; umt-ck: ubiquitous mitochondrial creatine kinase. focal injury vascular damage neuroinflammation oedema cr mtbi ↓ cerebral blood flow ↓ oxidative respiration ↑calcium ↑glycolysis ↑lactic acid ↑ionic flux hypoxia ↑calcium ↑ros ↑calcium hypoxia diffuse injury ionic flux membrane depolarisation membrane repolarisation spreading depression axon disconnection axon swelling glutamate release atp atp pcr pcr cr cr cell damage inflammation oxidative stress mptp cell death dysfunctional mitochondria protease activation d e cr e a se de cre ase decrease in cr ea se adp atp umt-ck bb-ck more efficient degrade ion channel degrade axon structure axon disconnection cell death atp pump: reduce calcium atp pump: reduce calcium . /cnc- - concussion ( ) cnc future science groupfuture science group review dean, arikan, opitz & sterr likelihood of mptp developing in the mitochondria by protecting against the factors involved in their forma- tion. the cr/pcr/ck system may also help stabilize the mptp, preventing it from opening and releasing proteins into the cytosol to induce apoptosis [ , , ], although this effect may be weak or indirect [ , ]. cre- atine may therefore play a role in the moderation of oxidative stress, intracellular calcium and apoptotic effects in neurons after mtbi. finally, there is tentative evidence that creatine could potentially influence edema, inflammation and altered neurotransmission after mtbi (figure a). creatine is an osmolyte, with supplementation leading to increased water retention [ , , ]. in this way, creatine retention or release can alter water retention and osmolarity of cells exposed to hyper- and hypo-osmotic stress (e.g., in edema or calcium influx) [ , ]. creatine has also been ascribed a putative anti-inflammatory role, reducing the appear- ance of inflammation markers and perhaps dampening immune response [ , , ]. however, the exact mechanism of this effect is unknown, and may be secondary to its effects on energy metabolism and scavenging of free radi- cals (see figure ). lastly, there is evidence that creatine may act like a neurotransmitter, with an agonist effect on gaba receptors, and some evidence of an influence on n-methyl-d-aspartate receptors [ , , , ]. in summary, there is considerable overlap between the role of creatine and the neuropathology of mtbi (figure & table ). creatine’s role in energy homeo- stasis, keeping atp levels constant and increasing the efficiency of mitochondrial oxidative respiration has particular potential value during the generalized energy crisis observed after mtbi. in addition, creatine has a role in calcium homeostasis, reducing oxidative stress and potentially aiding in edema, neuroinflam- mation and altered neurotransmission. evidence for altered creatine after mtbi in general, the most consistent finding in the acute stage after mtbi is reduced n-acetyl aspartate (naa; suggest- table . overlap between mild traumatic brain injury neuropathology, role of creatine and symptom report. mtbi neuropathology† creatine role‡ pcs symptoms† membrane depolarization – ionic flux – spreading depression – maintains/restores membrane potentials [ ] – ‘atp buffer’ [ ] migraine-like symptoms (headache, dizziness, light and sound sensitivity) calcium influx – impair mitochondria – activate proteases – possible apoptosis – axonal transport and structure effected (cytoskeleton/microtubules) – plays a role in calcium homeostasis [ ] – prevents influx of calcium – atp buffer (cell transport) [ ] pcs symptoms, specifically cognition (related to axonal dysfunction/cell death) impaired mitochondrial function – plays a role in calcium homeostasis [ ] – prevents influx of calcium – stimulates respiration [ , ] – prevents formation of mptp and stabilizes mptp, preventing pore opening [ ] increased vulnerability (second impact syndrome) oxidative stress – production of ros & free radicals – reduces ros by aiding mitochondria [ ] – directly scavenges free radicals [ ] increased vulnerability (second impact syndrome) glutamate excitotoxicity – aids neurotransmission and reuptake [ ] – protects against glutamate toxicity lactate accumulation buffers lactate accumulation by reducing glycolysis [ , ] swelling/edema used as osmolyte in brain [ ] inflammation – putative anti-inflammatory role [ , ] – role in reducing glutamate excitotoxicity altered neurotransmission balance – reduced gaba – altered inhib–exit balance putative role as neurotransmitter for gaba and nmda receptors [ , ] pcs symptoms, specifically cognition (related to axonal dysfunction/cell death) †data taken from [ , ]. ‡data taken from [ , ]. inhib–excit: inhibitory-excitatory; mptp: mitochondrial permeability transition pores; mtbi: mild traumatic brain injury; nmda: n-methyl- d -aspartate; pcs: post- concussion syndrome; ros: reactive oxygen species. www.futuremedicine.com . /cnc- - www.futuremedicine.com future science groupfuture science group creatine supplementation following mtbi review future science group ing neuronal loss [ – ]), with some evidence of increased choline (suggesting cell turnover or loss [ ]), lactate (gly- colysis [ ]) and myoinositol (suggesting inflammation and osmotic stress [ ]). furthermore, naa is reduced more in those with greater postconcussion syndrome (pcs) [ ], and correlates with cognitive performance [ ]. however, findings for total creatine are more variable, with both increases [ , ] and decreases [ , ] observed after mtbi. this variability may be due to the areas investigated in these studies, as creatine concentration is highest in gray matter areas (cerebral cortex, hippo- campus, olfactory bulb, brainstem, cerebellum, spinal cord) and lowest in white matter areas and basal gan- glia [ , ]. furthermore, there is differential expression of the creatine transporter (crt; required for creatine uptake) along similar lines [ ]. if split by tissue type, the creatine results become more understandable, with increased creatine observed in white matter areas [ ], and no difference or reduced creatine in gray matter or mixed areas [ , ]. therefore, in areas with high creatine concentration (gray matter), the general finding is either unaltered or reduced creatine [ , ]. the degree of altera- tion may depend on the severity of injury, or the propor- tion of gray and white matter in mixed areas. further- more, the reduced gray matter creatine (usually high) and increased white matter creatine (usually low) could indicate some breakdown in the spatial energy buffer function. overall, these findings suggest that mtbi can directly affect neural creatine stores, and there is evidence of a correlation between creatine and cognitive performance [ ], as well as time since injury [ ]. there is also recent evidence for reduced creatine concentration in gray matter areas (primary motor area and dorsolateral prefrontal cortex) over the course of an american football season, even when no mtbi was recorded [ ]. this reduction in total creatine was related to the number of high force ( +g) subcon- cussive impacts recorded [ ]. these studies demon- strate a relationship between head impact and creatine concentration at a subconcussive level, and suggest a mechanism for the increased vulnerability to injury (second impact syndrome, discussed in the next section [ , , ]). in addition, the use of longitudinal data, with baseline (preseason) concentration measure- ments, allow firmer conclusions to be drawn about the relationship between head impact and creatine. the relative paucity of studies into creatine differences after mtbi could be due to the fact it was thought to be stable within both clinical and nonclinical popula- tions, and so is typically used as an additional reference within magnetic resonance spectroscopy (mrs) analy- ses (e.g., naa/cr). however, creatine concentration is not constant [ ], as it depends on tissue type, amount of activity, degree of vasculature, and varies across clini- cal groups [ ]. there is clearly a need for more research, as current findings indicate that mtbi may affect neu- ral creatine concentration, and that the concentration postinjury is related to cognitive performance. overlap in symptoms after an mtbi, individuals commonly report a number of somatic, cognitive and emotional symptoms, collec- tively known as pcs. there is evidence that these symp- toms may result from aspects of the neurometabolic cascade observed after mtbi. for instance, the initial ionic flux could underlie very acute pcs symptoms. it induces a ‘spreading depression’ very similar to that seen in migraine, with similar symptoms reported (headache, nausea, light sensitivity, sound sensitivity and dizzi- ness) [ ]. some pcs symptoms may also be explained by axonal dysfunction and altered neurotransmission after mtbi. indeed, this relationship has been observed in diffusion tensor imaging ([ – ]) and functional mri ([ – ]) studies, with altered structure (axonal integrity) and function related to slowed cognition and reaction time. in addition, the cellular energy crisis seen after mtbi may last for a considerable time after injury, and may even be present after subconcussive injury [ , ]. this energy crisis not only impacts on somatic and cog- nitive function as mentioned above but also increases vulnerability to a second injury with potentially longer- lasting and more severe deficits (second impact syn- drome [ , , ]). this ‘window’ of vulnerability could also mean that compensation mechanisms develop on a behavioral or physiological level, with perhaps greater effort or altered neural functioning underlying some pcs symptoms such as fatigue and headache [ ]. it is clear that creatine’s role in energy homeostasis is directly associated with the cellular energy crisis, ionic flux, axonal disconnection and altered neurotransmis- sion, which may underlie pcs symptom report after mtbi (see table for summary of biological overlap with symptom report). however, further evidence for the potential role of creatine in pcs symptom report comes from individuals with impairments in creatine metabolism. for instance, impairment in the cr/pcr/ ck system can cause predisposition to migraines [ ], perhaps via a reduced ability to control for ionic flux, developing into ‘spreading depression’, similar to the state observed after mtbi. individuals with extremely low neural creatine concentration, due to genetic alterations in creatine synthesis or transport, exhibit symptoms such as mental retardation, language delay, developmental delay, motor disorders and neurological symptoms (e.g., seizures) [ , , ]. these are much more severe symptoms than those observed in pcs, but dem- onstrate the necessity of creatine for typical cognitive and motor function. large alterations in creatine cause . /cnc- - concussion ( ) cnc future science groupfuture science group review dean, arikan, opitz & sterr drastic symptoms, but this also suggests that less severe symptoms may be caused by the relatively small altera- tions observed after mtbi. furthermore, and of clear relevance to this review, early use of creatine supplemen- tation in individuals with creatine synthesis deficien- cies can alleviate these symptoms, and may reduce the majority of these effects on the brain [ , , ]. creatine supplementation creatine supplementation is predominately used to enhance muscle function in athletes [ ], the military [ ] and in clinical movement disorders [ , ]. however, there is also research into whether supplementation may enhance cognition in general nonclinical [ ] and ageing popula- tions [ ], as well as the possibility of using it as a neu- roprotective in neurodegenerative diseases (e.g., parkin- son’s disease, huntingdon’s disease, alzheimer’s disease, amyotrophic lateral sclerosis, charcot-marie-tooth’s disease, fibromyalgia) [ , , , , ], psychiatric disorders (e.g., schizophrenia, bipolar disorder, major depression, anxiety disorders and psychological stress) [ , ] and brain injury (both tbi [ – , ] and stroke [ , , , ]). the extensive list of applications gives an idea of the scope of research into the neural effects of creatine supplementa- tion. however, underneath each of these applications is the effect of creatine on cerebral energy depletion, oxida- tive stress and mitochondrial dysfunction [ ] or evidence of altered creatine metabolism within the clinical state (e.g., psychiatric diseases [ ]). creatine supplementation in (m)tbi several reviews have suggested the applicability of cre- atine supplementation to tbi [ , ], and there is a strong case for the potential of creatine in mtbi (see previ- ous section). despite this, there are no known studies into the effect of such supplementation on mtbi, and very few studies examining its effect on tbi. however, those studies that exist show promising results, and will be discussed in this section. in animal models, creatine supplementation prior to experimental tbi reduced cortical damage ( – % reduction) by protecting mitochondrial function (mito- chondrial membrane potential increased, lower intra- mitochondrial ros and calcium, atp levels main- tained) [ ] and protected against some of the effects of oxidative stress (but not seizure susceptibility) [ ]. higher levels of supplementation produced a greater degree of neuroprotection, as indicated by lower mark- ers of secondary injury (lactate and free fatty acids) [ ]. however, an in vitro study of rat hippocampal cells sug- gested that creatine supplementation may not have a direct protective effect for oxidative stress, with protec- tive effects perhaps based on reduced glutamate and cal- cium excitotoxicity and increased atp/pcr levels [ ]. in clinical populations, the only studies known to date come from sakellaris and colleagues [ – ]. these studies investigated the effects of creatine supple- mentation ( . g/kg in oral suspension for months) after tbi (glasgow coma scale: – ; within h of time of injury) in children and adolescents (age: – years old) [ – ]. administration of creatine reduced post-traumatic amnesia and improved recovery [ – ], cognitive function [ ], headaches, dizziness and fatigue [ ], as well as language articulation and under- standing [ ]. it should be noted that these studies were conducted in children, after severe to moderate tbi, in open-label trials. overall, these studies demonstrate that creatine supplementation after tbi causes alterations in bio- logical markers related to mtbi neuropathology (in animal models), as well as improved outcome and reduced symptom report (in clinical studies) in areas expected from the overlap between mtbi, creatine and symptom report (see figure & table ). further inves- tigation is therefore warranted for the potential use in mtbi populations, using double-blind interventions. creatine supplementation in other nonclinical & clinical groups there are further indications of the utility of creatine supplementation for mtbi in its effects on nonclinical and clinical populations. in nonclinical populations, creatine supplementation has been shown to increase cognitive performance, in particular working memory and speed of processing, in both young and old partici- pants [ , , ]. along with subjective report of attention and memory problems, objective working memory and speed of processing deficits are also commonly observed after mtbi [ ]. creatine supplementation has also been shown to reduce blood–oxygen level-dependent (bold) response in a functional mri visual process- ing task [ ]. this reduction in bold response may be due to increased pcr stores reducing the immediate need for increased oxygen and glucose from the blood. it also demonstrates the potential for creatine to ameliorate the altered bold response during cognitive tasks observed after mtbi [ ]. of particular interest to mtbi research, the effect on cognition is greatest when creatine is supple- mented prior to an intervention that compromises cell energy status, such as experimental hypoxia [ , , ]. in addition, creatine supplementation prior to experimental ischemia in animal models and in vitro studies resulted in reduced damage, lower lactate and higher atp in supple- mented animals [ ]. this is a similar state to the cellular energy crisis after mtbi, and demonstrates strong poten- tial for neuroprotective effects of creatine administered prior to injury. finally, there is some evidence that cre- atine may improve outcome in mood disorders such as www.futuremedicine.com . /cnc- - www.futuremedicine.com future science groupfuture science group creatine supplementation following mtbi review future science group depression [ ] and post-traumatic stress disorder [ ], both of which are common co-morbid diagnoses after mtbi. creatine supplementation summary the literature on creatine supplementation after tbi is sparse, but those studies that do exist suggest a potentially useful role for this compound in alleviat- ing secondary damage after injury as well as protecting against damage if administered pre-injury. the possi- ble protective role is particularly interesting when con- sidering that two populations with high risk of mtbi are already taking this compound to some degree – athletes [ ] and the military [ ]. this fact would enable longitudinal studies into ability of creatine supplementation to protect against the effects of mtbi and subconcussive injury over a season or deployment. however, it is clear from the literature on creatine supplementation that promising findings in animal models or in vitro have not always been followed by conclusive findings in human participants [ ], particu- larly in clinical populations [ ]. therefore, the use of creatine as a neural supplement still requires research, as there are many unanswered questions and many f actors influencing its potential utility. factors to consider for creatine supplementation the most pressing factor influencing the efficacy of creatine supplementation is its pharmacokinetics [ ]. specifically, how much does supplementation actually increase creatine levels in the brain? dietary creatine reaches the neurons by crossing from the gut into the bloodstream, and must then be transported across the bbb. the increase in neural creatine after supplemen- tation would depend on the mechanisms for creatine transport (and synthesis) in the brain, the timing of administration, dosing regimen, the type and form of creatine administration, and individual factors such as age and gender. in addition, researchers must be aware of the safety considerations for supplementation. creatine synthesis & transport in the brain the majority of individuals get around half of the typi- cal daily requirement for creatine (∼ g/day [ , ]) from a diet that contains meat and dairy products [ , , , , ], with the other half being synthesized within the body [ , , ]. this synthesis is a two-step process occur- ring predominately in the kidneys and liver [ , ], but also in the brain [ , , ]. in brief, in the first step the enzyme agat converts arginine and glycine into gua- nidinoacetatic acid, and in the second step the enzyme gamt converts this guanidinoacetatic acid and s-ade- nosylmethionine into creatine [ , ]. both dietary and endogenously synthesized creatine is taken up into cells using a crt [ , ]. the final stage in the cycle of creatine is its breakdown into creatinine, which is then removed in the urine (∼ . – % or g/day) [ , ]. crts at the bbb are essential for supplementary cre- atine to enter the brain. however, although crt are present within neurons, oligodendrocytes and on the microcapillary endothelial cells that line the bbb, they do not seem to be present in the astrocytic feet which cover around % of the bbb [ , , ]. this leaves only a small amount of surface available for creatine absorp- tion, and may therefore mean that effects of supplemen- tation are at most small and slow-acting. indeed, creatine supplementation does not significantly change neural creatine concentrations, or aid symptoms, in individuals with crt deficiencies [ , , ], highlighting its key role in neural uptake. in contrast, individuals with intact crt, but deficient in creatine synthesis, show marked improvements in neural creatine concentrations, as well as symptom alleviation and reduced neural damage after long-term supplementation [ , , ]. this demon- strates that despite their relatively low expression at the bbb, crts are capable of absorbing creatine from the plasma in sufficient q uantities over time. creatine synthesis is tightly regulated to keep neu- ral levels stable, so increased uptake of dietary cre- atine may result in reduced endogenous synthesis as a homeostatic mechanism [ ]. evidence for the poten- tial power of this homeostatic mechanism comes from studies looking at neural creatine concentration in vegetarians and vegans, who may receive little or no dietary creatine [ ]. if dietary intake is essential, then vegetarians and vegans should have lower muscular and neural creatine. however, it seems that although mus- cle creatine levels are lower in vegetarians [ ], neural levels are similar to omnivores [ ]. it therefore appears that endogenous creatine synthesis may be able to com- pensate for reduced dietary intake, using homeostatic mechanisms to keep neural concentrations similar to those in omnivores. neural increase of creatine after supplementation as creatine supplementation may produce only small and slow acting effects on neural creatine concentrations, it is imperative for future studies to monitor both the neu- ral creatine concentration (using mrs) and the clinical effects of supplementation (e.g., cognition) [ , ]. current studies have predominately examined these factors in iso- lation, precluding direct investigation of the relationship between creatine concentration and clinical outcome [ ]. this is particularly important because creatine supple- mentation may have a greater peripheral (e.g., muscu- lar) effect in comparison to its putative role in cognitive enhancement and neuroprotection. . /cnc- - concussion ( ) cnc future science groupfuture science group review dean, arikan, opitz & sterr ta b le . c re a ti n e s u p p le m e n ta ti o n : d o si n g , n e u ra l cr e a ti n e l e ve l, b e h a vi o ra l e ff e ct s a n d s tu d y sp e ci fi cs . c re a ti n e d o se a n d t ri a l ty p e n e u ra l cr e a ti n e b e h a v io ra l e ff e ct s s tu d y s p e ci fi cs s tu d y ( y e a r) r e f. . g /k g p e r d a y in s o lu ti o n f o r m o n th s ( g /d a y fo r k g p e rs o n ) o p e n -l a b e l, r a n d o m iz e d t o in te rv e n ti o n /c o n tr o l n /a – r e d u ce d p ta – i m p ro ve d r e co ve ry , co g n it iv e f u n ct io n , la n g u a g e – r e d u ce d h e a d a ch e , d iz zi n e ss , fa ti g u e – y e a rs o ld , p o st -t b i sa k e ll a ri s e t a l. ( , , ) [ – ] × g /d a y ( g ; c rm o ) fo r w e e k r a n d o m iz e d , d o u b le b li n d , cr o ss o ve r d e si g n ( w it h p la ce b o , w a sh o u t: w e e k s) to ta l cr e a ti n e i n cr e a se i n : p ri m a ry m o to r a re a ( . % ; . ± . v s . ± . ; – % g m ) – r e d u ce d d e fi ci t in a tt e n ti o n c a p a ci ty – c o rt ic o m o to r e xc it a b il it y in cr e a se d – n o n cl in ic a l – e xp e ri m e n ta l h yp o xi a a ft e r cr e a ti n e o r p la ce b o tu rn e r e t a l. ( ) [ ] × g /d a y ( g ; c rm o ) fo r w e e k , r a n d o m iz e d , d o u b le b li n d , cr o ss o ve r d e si g n ( w it h p la ce b o , w a sh o u t: w e e k s) c r/ n a a i n cr e a se i n : – p ri m a ry m o to r a re a jm r u i: ( . % ; . ± . v s . ± . ) – lc m o d e l: n o t si g n ifi ca n t ( % ; . ± . v s . ± . ) n /a n o n cl in ic a l tu rn e r e t a l. ( ) [ ] a : si n g le d o se g ( c rm o ) b : × g ( g )/ d a y fo r w e e k s lo n g it u d in a l st u d y, n o c o n tr o l g ro u p a : n o s ig n ifi ca n t ch a n g e b : to ta l cr e a ti n e i n cr e a se i n : – p a ri e ta l g m ( . % ) – p a ri e ta lo cc ip it a l w m ( . % ) – c e re b e ll u m ( . % ) – t h a la m u s ( . % ) n /a n o n cl in ic a l d e ch e n t e t a l. ( ) [ ] lo a d in g : × . /k g p e r d a y in so lu ti o n ( c rm o ) fo r w e e k ( × g o r g /d a y fo r k g p e rs o n ) m a in te n a n ce : × . /k g p e r d a y in so lu ti o n f o r w e e k ( × g o r g / d a y fo r k g p e rs o n ) lo n g it u d in a l, c o n tr o l g ro u p ( n = ) to o k s u cr o se c r/ c h o i n cr e a se i n : le ft f ro n ta l lo b e ( . % ; c r/ n a a in cr e a se : . % ; . % g m ) β -a t p r e d u ct io n i n : -c m s li ce a cr o ss o rb it o fr o n ta l/ o cc ip it a l co rt e x ( . % ) n o s ig n ifi ca n t in cr e a se i n p c r ( . % ) in s a m e a re a n /a n o n cl in ic a l ly o o e t a l. ( ) [ ] b o ld :  b lo o d – o xy g e n  l e ve l- d e p e n d e n t  (f u n ct io n a l m r i s ig n a l) ;  c h o :  c h o lin e ;  c r:  c re a ti n e ;  c rm o :  c re a ti n e  m o n o h yd ra te ;  g m :  g ra y  m a tt e r;  j m r u i:  m a g n e ti c  re so n a n ce  u se r  in te rf a ce  f o r  ja va ;  lc m o d e l:  l in e a r  co m b in a ti o n  m o d e l;  n /a :  n o t  a p p lic a b le ;  n a a :  n -a ce ty l a sp a rt a te ;  p c r:  p h o sp h o cr e a ti n e ;  p ta :  p o st -t ra u m a ti c  a m n e si a ;  t b i:  t ra u m a ti c  b ra in  in ju ry ;  w m :  w h it e  m a tt e r. www.futuremedicine.com . /cnc- - www.futuremedicine.com future science groupfuture science group creatine supplementation following mtbi review future science group ta b le . c re a ti n e s u p p le m e n ta ti o n : d o si n g , n e u ra l cr e a ti n e l e ve l, b e h a vi o ra l e ff e ct s a n d s tu d y sp e ci fi cs ( co n t. ). c re a ti n e d o se a n d t ri a l ty p e n e u ra l cr e a ti n e b e h a v io ra l e ff e ct s s tu d y s p e ci fi cs s tu d y ( y e a r) r e f. × g /d a y ( g , c rm o ) in s o lu ti o n fo r w e e k p re – p o st , n o c o n tr o l g ro u p to ta l cr e a ti n e i n cr e a se i n : h ip p o ca m p u s ( . % ) r e d u ce d a t p i n : – m e d ia l te m p o ra l lo b e ( . % ) – st ri a tu m ( . % ) n o s ig n ifi ca n t ch a n g e i n p c r n /a n o n cl in ic a l p a n & t a k a h a sh i ( ) [ ] × g /d a y ( g ) fo r d a ys fo ll o w e d b y : g /d a y fo r d a ys p re -p o st , co n tr o l g ro u p ( n = ) to o k m a lt o d e x tr in n /a – r e d u ce d b o ld r e sp o n se i n vi su a l a re a s – b e tt e r p e rf o rm a n ce o n m e m o ry t a sk n o n cl in ic a l h a m m e tt e t a l. ( ) [ ] × g /d a y ( g , c rm o ) fo r d a ys fo ll o w e d b y : g /d a y fo r w e e k s r a n d o m iz e d , d o u b le b li n d , d e si g n w it h p la ce b o ( d e x tr o se ) n /a n o c h a n g e i n c o g n it io n n o r d e p re ss io n e ld e rl y w o m e n ( – ye a rs o ld ) a lv e s e t a l. ( ) [ ] × g /d a y ( g , c rm o ) a s ta b le ts fo r d a ys p re -p o st , co n tr o l g ro u p ( n = ) to o k g lu co se n /a v e g e ta ri a n /v e g a n : c re a ti n e i m p ro ve d p e rf o rm a n ce o n m e m o ry ta sk ( w o rd r e ca ll ) a ll p a rt ic ip a n ts ( m e a t- e a te r, ve g e ta ri a n /v e g a n ): c re a ti n e r e d u ce d v a ri a b il it y in r e a ct io n t im e t a sk p o st - su p p le m e n ta ti o n v e g e ta ri a n /v e g a n fe m a le s (n = ) co m p a re d t o o m n iv o re s (n = ) b e n to n & d o n o h o e ( ) [ ] b o ld :  b lo o d – o xy g e n  l e ve l- d e p e n d e n t  (f u n ct io n a l m r i s ig n a l) ;  c h o :  c h o lin e ;  c r:  c re a ti n e ;  c rm o :  c re a ti n e  m o n o h yd ra te ;  g m :  g ra y  m a tt e r;  j m r u i:  m a g n e ti c  re so n a n ce  u se r  in te rf a ce  f o r  ja va ;  lc m o d e l:  l in e a r  co m b in a ti o n  m o d e l;  n /a :  n o t  a p p lic a b le ;  n a a :  n -a ce ty l a sp a rt a te ;  p c r:  p h o sp h o cr e a ti n e ;  p ta :  p o st -t ra u m a ti c  a m n e si a ;  t b i:  t ra u m a ti c  b ra in  in ju ry ;  w m :  w h it e  m a tt e r. . /cnc- - concussion ( ) cnc future science groupfuture science group review dean, arikan, opitz & sterr indeed, creatine supplementation has been shown to increase creatine concentration in plasma [ ] and mus- cles [ ]. despite the potentially poor bbb permeabil- ity, a few studies have also demonstrated that creatine supplementation can result in significant increases in neural creatine and pcr [ , – ] (see table ). only one of these studies looked at outcome measures, and found that creatine supplementation increases neural cre- atine in primary motor cortex and protected against a hypoxia-induced reduction in attention [ ]. this study allows direct comparison of neural creatine alteration and behavioral performance and elegantly de monstrates the potential for creatine supplementation. it seems that identification of statistically significant changes in creatine may depend on the neural area stud- ied. the concentration of creatine varies across neural areas [ , ], and greater magnitude increases may be observed in those areas with lower presupplementation concentrations [ , ]. indeed, one study did demonstrate greater increase in white matter ( . %, initially low creatine area) compared with gray matter and cerebel- lum ( . and . %, initially high creatine areas) after supplementation (see table ) [ ]. therefore, the choice of neural area(s) to sample after creatine supplementa- tion is an important methodological issue. the choice of analysis tool also seems to be potentially important, with one study suggesting that the jmrui software uses a technique that is more sensitive to subtle changes in creatine compared with lcmodel [ ]. measurement of creatine concentration changes after supplementation is therefore methodologically possible, but potentially chal- lenging in terms of correct choice of acquisition param- eters and analysis tools. in particular, methods develop- ment is required to enable reliable identification of more subtle concentration changes and to reduce v ariability in p lacement of mrs voxel across acquisitions. timing of supplementation as discussed previously, the results from clinical trials have been variable despite very promising findings from animal and in vitro models. this could be due to the tim- ing of creatine supplementation. in animal models, cre- atine can be given prior to injury, resulting in an imme- diate neuroprotective effect. however, in clinical studies, creatine supplementation can only be started after the clinical condition has been diagnosed. this will at best be in the subacute stage (within hours) after injury, when damage will already have occurred. furthermore, as the putative neural increase in creatine is slow, further sec- ondary damage might occur before an effective concen- tration is reached. post-injury creatine supplementation may therefore be too late to enable some of the protective effects of creatine [ ], resulting in reduced efficacy in comparison to the animal models. the timing of supplementation is therefore likely to be critical for the scale and nature of the effect it exerts. animal models with pre-tbi supplementation show larger neuroprotective effects such as reduced cortical damage, oxidative stress (ros) and improved mitochondrial function [ – ], whereas clinical studies with post-tbi supplementation demonstrate improved symptom report such as cognitive function, headaches and fatigue [ – ]. we would therefore predict that cre- atine supplementation will have much greater efficacy in reducing neural damage and moderating pcs symp- toms if used as a pre-emptive neuroprotective in high- risk populations (e.g., athletes and military [ , ]), rather than a postinjury medication. these high-risk popu- lations for mtbi are already taking creatine to some degree in order to improve muscle strength and stam- ina [ , ], meaning the potential neuroprotective effects of this compound could be relatively easily studied. strength, length & dosing regime in creatine supplementation previous studies use a variety of dosing regimens for creatine supplementation, and no definitive guidelines have been set [ ]. in general, traditional supplemen- tation protocols include a short ( – days) ‘loading phase’ with high-dose creatine ( – g/day) and/or a longer duration ‘maintenance phase’ of – months ( – g/day) [ , , ] (e.g., see table ). as neural uptake of creatine is slow, it seems that prolonged administra- tion (several days) and/or high dose is required [ , , ], with studies using short supplementation or doses lower than g reporting no significant changes in neural creatine [ , ]. it has also been suggested that the difference in outcome between animal models and clinical trials in humans [ ] may be due to the size of the dose given (several times higher in animals) [ ]. however, doses of up to g/day have been trailed in individuals with huntington’s disease with little clini- cal effect [ ], and (biological) effects are observed in animal models with doses comparable to human trials ( . g/kg or g for kg) [ ]. furthermore, there may be a u-shaped dose–response curve, where lower doses are not enough to increase neural creatine, but higher doses may actually slow the absorption of creatine [ , ]. more specifically, higher doses may saturate crts in the intestines causing their downregulation [ ], with the majority of the dose being simply excreted [ ], and may be more likely to trigger other homeostatic mechanisms such as reduction in endogenous creatine synthesis [ ]. high doses of cre- atine may also have issues for safety in short- or long- term supplementation (see the ‘safety of creatine supple- mentation’ section). for this reason, studies usually split creatine supplementation into smaller doses across the www.futuremedicine.com . /cnc- - www.futuremedicine.com future science groupfuture science group creatine supplementation following mtbi review future science group day, with some variability in the number and strength of doses (table ). in general, multiple small doses (e.g., – g across the day, see table ) are preferred, with long-term doses greater than g potentially hav- ing a counter-productive effect [ ]. finally, the form of administration and type of com- pound also influence uptake of creatine. orally admin- istered creatine must be able to survive the highly acidic stomach environment (which may break it down to cre- atinine [ ]) to be transported from the intestines (where bacteria may also break it down) into the bloodstream. the form of administration (solution, powder or cap- sule) influences its ability to negotiate these environ- ments as well as the speed it is absorbed into the plasma. creatine in solution reaches peak plasma concentration first, and all supplemental creatine peaks quicker than dietary creatine [ ]. one final obstacle for creatine to negotiate after supplementation is the bbb, where the limited amount of crt means neural uptake is small and slow-acting. a number of compounds have been trialled for their increased ability to penetrate the bbb, with cyclocreatine and pcr–mg complex acetate both able to enter the brain even when the crt is inactive [ ]. creatine ethyl ester also has increased cell permeability, and is stable at lower ph, increasing its stability in the stomach environment [ ]. these are potentially useful compounds for future research. however, the majority of studies use creatine monohydrate in solution as part of their supplementation protocol (see table ). interindividual variability effects on creatine supplementation individual variation in diet, age and gender has been sug- gested to influence neural creatine levels, which in turn has been suggested to influence the effects of creatine supplementation (greater effects observed in areas with lower presupplementation creatine concentration) [ , ]. as discussed previously, the differences in dietary uptake of creatine between vegetarians and omnivores exhibit no influence on neural creatine concentration [ ]. current research reports both decreased [ ] and increased [ ] neural creatine with increasing age. this discrepancy could be due to marginal changes over age or due to variation in neural area investigated. the effect of healthy ageing on neural creatine has not been sufficiently researched, and longitudinal data are lack- ing [ ]. this is of particular interest as cerebral energy depletion plays a major part in brain injury and is thought to be an underlying factor in some age-related neurodegenerative diseases [ ]. there is also limited evidence for gender-related differ- ences in creatine concentration, with one study reporting lower frontal lobe pcr concentration in healthy women compared with healthy men [ ]. in addition, creatine supplementation showed some benefit in female, but not male, rats in a model of depression [ ]. this does suggest some interaction between gender and creatine efficacy, at least in depression, and may be due to the influence of gender-related hormones and hormone cycles [ ]. as the menstrual cycle also influences pcs symptom report after mtbi [ ], and given the putative neuroprotective role of progesterone [ ], this is particularly relevant to the d evelopment of e ffective creatine applications in mtbi. safety of creatine supplementation side effects such as muscle cramping, diarrhea, nausea, vomiting, dehydration, water retention, mood altera- tion and kidney dysfunction have been reported after creatine supplementation [ , , , , ]. muscle cramps and gastrointestinal distress (diarrhea, nausea, vomit- ing) are likely due to altered osmotic balance and dehy- dration [ ]. as such, it is recommended to drink extra water during supplementation, make sure that the sup- plement is fully dissolved before ingestion, avoid single high doses (perhaps > g) [ , ] and avoid caffeine [ ]. creatine supplementation can cause high creatinine in the urine (due to increased creatine breakdown), which is sometimes used as an indicator of kidney dysfunc- tion and may therefore lead to false positives in these tests [ ]. however, to ensure safe supplementation, it is recommended to spread the dose out evenly through- out the day, or use slow-release creatine to reduce any possible buildup of toxic compounds. in general, creatine supplementation in traditional doses, using pure compound, is deemed safe [ , ]. how- ever, use of creatine with other compounds known to have an adverse effect of kidney function may be unwise [ ]. long-term supplementation at or below g/day is considered safe, with more data required for higher doses, although there is no indication for safety concerns [ ]. regular recording of kidney function dur- ing high-dose creatine supplementation is recommended to help early identification of unintended side effects and provide empirical data for the safety of such a regime [ ]. as discussed above (see the ‘strength, length and dosing regime in creatine supplementation’ section), high-dose creatine may also have effects in regulation of creatine synthesis and uptake, though this should stabilize after supplementation is discontinued. conclusion & future perspective creatine supplementation demonstrates potential as a neuroprotective when administered prior to or after mtbi. there is significant overlap between the neu- ropathology of mtbi, the cellular role of creatine and pcs symptom report, as well as evidence of neural cre- atine alterations after mtbi and subconcussive injury. furthermore, supplementation before experimental . /cnc- - concussion ( ) cnc future science groupfuture science group review dean, arikan, opitz & sterr tbi reduced markers of cellular damage and energy crisis, and supplementation after clinical tbi improved outcome and reduced symptom severity. however, despite this promise, there is no known research l ooking s pecifically at supplementation after mtbi. creatine is a safe, naturally occurring compound, both endogenously synthesized and present in the diet, and is widely used as a supplement to build muscle strength and stamina. the efficacy of creatine supple- mentation for neural effects requires greater scrutiny; its ability to increase neural creatine concentration depends on an effective dose regime as well as differ- ences in presupplementation creatine concentration. the exact mechanism and pharmocokinetics of cre- atine supplementation for neural effects has yet to be fully understood. for this reason, it is essential that supplementation studies monitor neural creatine con- centration as well as behavioral and clinical outcome to allow firm conclusions to be drawn. looking forward, there is a large gap in the litera- ture on creatine supplementation, with future studies required to investigate its potential following mtbi. in particular, creatine supplementation may have much greater efficacy if used as a pre-emptive neuroprotec- tive in populations at high risk of mtbi (athletes and military), rather than a postinjury medication. as these high-risk populations are already taking supplement to some degree for muscle strength and stamina, this may enable longitudinal studies investigating neuroprotec- tion against the effects of mtbi and subconcussive injury over a season or deployment. these future studies should also bear in mind the dosing regimen and safety recommendations detailed in this review. financial & competing interests disclosure the authors have no relevant affiliations or financial involve- ment with any organization or entity with a financial  inter- est in or financial conflict with the subject matter or mate- rials discussed in the manuscript. this includes employment,  consultancies, honoraria, stock ownership or options, expert  testimony, grants or patents received or pending, or royalties. no writing assistance was utilized in the production of this  manuscript. open access this  work  is  licensed  under  the  creative  commons  at- tribution  .   license.  to  view  a  copy  of  this  license,  visit  http://creativecommons.org/licenses/by/ . / executive summary the case for a role of creatine in mild traumatic brain injury •	 there is considerable overlap between the neuropathology of mild traumatic brain injury (mtbi) and the role of creatine in the brain. •	 neural creatine concentrations are altered after mtbi and subconcussive injury, with a reduction (or no change) in gray matter areas and an increase in white matter areas. •	 the post-concussion syndrome symptoms reported after mtbi share some similarity to those reported in individuals with impairments in creatine metabolism, and may both be due to a shared underlying cellular energy deficit. creatine supplementation •	 few studies have looked at creatine supplementation after traumatic brain injury (tbi), with none investigating mtbi. •	 however, these tbi studies demonstrate that creatine supplementation can have both neuroprotective effects in animal models (e.g., protect mitochondrial function, antioxidant effects and increased atp) and in clinical cohorts (e.g., improve recovery, reduce headache, dizziness, fatigue, improved cognition). •	 creatine supplementation also improves cognition in nonclinical populations, outcome in anxiety and depression-related mood disorders, and has a protective effect in situations that impair cell energy status. factors to consider for creatine supplementation •	 the efficacy of creatine supplementation is dependent on its ability to increase neural concentration, this increase may be small and slow due to limited creatine transporter at the blood–brain barrier. •	 other factors that affect efficacy are dosage regime (amount, doses/day, length of supplementation, type of administration, form of compound), prior neural concentration (which varies across areas and may be influenced by diet, age and gender) and tolerance (safety of administration, hydration status). •	 of particular interest, pre-emptive supplementation prior to injury (as in animal models) may have a greater neuroprotective effect than postinjury supplementation. conclusion & future perspective •	 creatine supplementation demonstrates potential as a neuroprotective both before and after tbi, but there is a gap in the literature for research into supplementation following mtbi. •	 in particular, creatine may have potential as a pre-emptive neuroprotective against mtbi and subconcussive injury in high-risk populations such as athletes and military personnel. http://creativecommons.org/licenses/by/ . / www.futuremedicine.com . /cnc- - www.futuremedicine.com future science groupfuture science group creatine supplementation following mtbi review future science group references knapik jj, steelman r a, 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( ), – ( ). dean pj, sterr a. long-term effects of mild traumatic brain injury on cognitive performance. front. hum. neurosci. , ( ). hammett st, wall mb, edwards tc, smith at. dietary supplementation of creatine monohydrate reduces the human f mri bold signal. neurosci. lett. ( ), – ( ). turner ce, byblow wd, gant n. creatine supplementation enhances corticomotor excitability and cognitive performance during oxygen deprivation. j. neurosci. ( ), – ( ). persky am, brazeau ga, hochhaus g. pharmacokinetics of the dietary supplement creatine. clin. pharmacokinet. ( ), – ( ). braissant o. creatine and guanidinoacetate transport at blood-brain and blood-cerebrospinal fluid barriers. j. inherit. metab. dis. ( ), – ( ). yazigi solis m, de salles painelli v, giannini artioli g, roschel h, concepcion otaduy m, gualano b. brain creatine depletion in vegetarians? a cross-sectional ( ) h-magnetic resonance spectroscopy (( )h-mrs) study. br. j. nutr. 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( ), r –r ( ). turner ce, russell br, gant n. comparative quantification of dietary supplemented neural creatine concentrations with ( )h-mrs peak fitting and basis spectrum methods. magn. reson. imaging ( ), – ( ). alves cr, merege filho ca, benatti fb et al. creatine supplementation associated or not with strength training upon emotional and cognitive measures in older women: a randomized double-blind study. plos one ( ), e ( ). benton d, donohoe r. the influence of creatine supplementation on the cognitive functioning of vegetarians and omnivores. br. j. nutr. ( ), – ( ). rawson es, venezia ac. use of creatine in the elderly and evidence for effects on cognitive function in young and old. amino acids ( ), – ( ). wunderle k, hoeger km, wasserman e, bazarian jj. menstrual phase as predictor of outcome after mild traumatic brain injury in women. j. head trauma rehabil. ( ), e –e ( ). sayeed i, stein dg. progesterone as a neuroprotective factor in traumatic and ischemic brain injury. prog. brain res. , – ( ). kim hj, kim ck, carpentier a, poortmans jr. studies on the safety of creatine supplementation. amino acids ( ), – ( ). 亚欧乱色视频 - 豆角电影网 | 飞一般影视速度 畅快影视体验 , 	 首页 	 , 	 连续剧 	 , 	 动漫 	 亚欧,乱,色,视频 , ： , 地区： 未知 年份： 未知 状态： , 主演： , ： 发布时间： - - : : 简介： 手机看片高清国产,二,总裁大人放肆,,范冰,,樱,富二代ap,十分,chinesefree普通话 详细 > , 	 	 	 	 	 	 	 	 , 介绍 	 	 	 手机,二十岁,总裁大人,元气满满的哥,范冰,向日葵,樱花视,,十分,chi 	 	 	 	 	 猜, 	 	 , 禁不禁 	 , 爱情的最后胜地 	 , 韩国美女组合k 	 	 , 韩国美女组合k 	 , 韩国美女组合k 	 , 韩国美女组合k 	 , 韩国美女组合k 	 , 韩国美女组合k 	 , 韩国美女组合k 	 , 韩国美女组合k 	 , 韩国美女组合k 	 , 韩国美女组合k 小丫头，在做什么。 乱温暖柔软的身体扑到我的怀里。 嫩的舌色头含住我的舌尖轻啜着。 如果有人煽动舆论视频，但是我们能够从中疏导，不让百姓亚欧偏听偏信就行了。 这样过了二乱十分钟左右，小色洁开始扭动她的身体，并很主动地猛吻我的脸和嘴视频，双手搂得我很紧，叫声已经不是喃喃细语了，而是放洩般地,,,,大喊叫，她快高潮亚欧的时候要比刘真来得激烈。当我感到她 “让我来照乱顾他们俩吧”尽管陆子剑已经失去了男根，尽管傻色尼姑了痴还像一头被激怒的母兽，绑住她都捆不住视频她的挣扎和咆哮,,,,，但念圭还是向妙深师太申请，为了缩小影响，就将陆子剑和精神失亚欧常的了痴都安排在了柴房里乱，让她来照顾他们，直到他们康复为止妙深师太也色没什么不答应的理由救死扶伤，积德行善嘛，也就同意了视频。 从敞开的大门，化身李妙春的妙深在梁星达兴,,,奋的解说下，亚欧看着那些奇异的风景，虽乱然在不住地点头表示无限惊喜，但内心里，色却在回想，当日赵灵芝和秦寿生也是这样被梁星达给诱惑到坑底的吧视频，当时的秦寿生和赵灵芝，还有赵灵芝肚子里的那个孩子，不,,,,,知道这是在向死亡的深渊下落吧 另一位门卫不赞亚欧同的目光落了过来，“都说了让你不要去评乱价这些住户你怎么就不听呢？色” 兄弟俩蹲了下来，颤抖地伸视频出手来在我妻子丰,,,,,满的ru房上细细的抚摸起来，妻子小巧诱人的||乳|亚欧头在他们 亚欧乱色视频 的抚摸下很快挺立起来，门那边开始传来妻子动情的呻乱吟…… 不愉快的挂色断电话，视频林悦开始自我检讨，难道真的想得妈妈说的那样是她任性了,,,？难道说真亚欧的无法改变现在的情况？ “胀？”我说：“乱我还有一半没放进去呢！” ”程杨千言万语却色不知道嘱咐些什么，只对方冰冰道：“你视频放心。 ,,,可过了不多时亚欧，她明显地感到了贯穿在她体内的巨物更加巨乱大了，那胀胀色的感觉，抽动时视频腔肉摩擦着巨物带起的麻痒感，让她尖叫着，疯狂地,,耸动着，从后亚欧面看去，她白嫩的肥臀如乱打桩机般急速起 	 	 	 		 		 	 		 	 	 	 	 elegantthemes ye authorize wordpress elegantthemes http://www.globalsepri.org/ f / .html 年 月 日 http://www.globalsepri.org/d / .html 年 月 日 http://www.globalsepri.org/ hl/k j e .html 年 月 日 http://www.globalsepri.org/ / m.html 年 月 日 http://www.globalsepri.org/ / h .html 年 月 日 http://www.globalsepri.org/ k e / g .html 年 月 日 http://www.globalsepri.org/ h b/ c a .html 年 月 日 http://www.globalsepri.org/ h d/ e .html 年 月 日 http://www.globalsepri.org/l d/ kf.html 年 月 日 http://www.globalsepri.org/ / .html 年 月 日 http://www.globalsepri.org/ i/ k d .html 年 月 日 http://www.globalsepri.org/ kn / .html 年 月 日 http://www.globalsepri.org/ak / l b.html 年 月 日 	 	 		 	 	 	 	 	 	 	 	 analysis of different solar panel arrangements using pvsyst analysis of different solar panel arrangements using pvsyst jones k. chacko m.tech scholar dept: of electrical and electronics engineering amal jyothi college of engineering kottayam, kerala, india prof. k. j thomas professor dept: of electrical and electronics engineering amal jyothi college of engineering kottayam, kerala, india abstract—to maximize the power generation from a limited area is one of the major concern due to increased land cost and unavailability of lands in urban areas. the solar pv module directly converts the incident solar radiations into useful electrical energy. the variation of temperature and solar irradiance are the major factors which affects the performance of the solar pv module. shading on solar pv modules reduces the life span of the system as well as reduce the performance of the system. here, three different arrangements of solar pv modules are done on a standalone system. in this work, the maximum generation was obtained from a three layer solar pv system with dual axis tracking system. by this arrangement we can reduce the space requirement to % to generate maximum energy. keywords—solar pv module; pvsyst; tracking; shading. i. introduction energy is a vital requirement to sustain and improve the standard of our daily lives. with the exponential growth in population, rapid spread of technology and advancement of globalization, energy consumption in the developing countries like india, is rising at a very fast pace. like many of the developing countries, india is also facing an immense shortage of energy. the electricity sector in india had an installed capacity of . gw as of end june [ ]. peak power deficit in the country fell to . % at , megawatts (mw) in april from . % a year ago due to increased capacity and lower electricity consumption by states. the decline in consumption in certain north indian states was due to a weak intra-state network for dissemination of electricity. according to the latest data by the central electricity authority (cea), the total requirement in the country last month was , , mw, as against the supply of , , mw a peak power deficit of . %[ ]. this shortfall necessitates load shedding. suffering of the common people is nowhere more pronounced than in urban areas where electricity is a necessity in carrying out daily activities. like most other places, solar energy has the promise and potential to solve the energy crisis of india as it is available throughout the country and does not need a broad technological base. it is projected that by the year , the solar pv electricity will also dominate compared to other sources of energy[ ]. from the study growth of photovoltaic, an average about % annual increase is noticed during the years to . from the study of cost economics of a solar photovoltaic power plant, pv modules cost about % and the other % is due to components, like transformers, cables, inverters, and civil works[ , ]. this work aims at solving this problem by introducing novel approach to arrange the solar panels in a way that minimizes the use of floor space. in this paper we compare different types of panel arrangement to get a particular kilowatts of energy and to save the land cost is to adopt a new methodology to get maximum output from the solar power plant in a limited area[ ]. here we were using a single layer panel, a single layer panel with tracking system and a three layer solar pv panel arrangement with solar tracking for comparison. for this purpose, the pvsyst[ ] modeling software has been used, and a design with a new concept for the solar pv module is suggested, and its advantages over conventional design were discussed. the rest of the paper been organized in the following way: chapter ii gives a brief description of the different solar panel structure and its operation. chapter iii deals with the overview different panel arrangements. chapter iv discussion of results of different arrangements with land cost. chapter v deals with conclusion. ii. methodology the basic characteristics of a solar parallel will depends up on type of solar cell, temperature of the cell and the radiations incident on it. the conversion efficiency of pv system is important factor to be determined in the power generation technologies. in this paper we used to analysis the performance with the help of pvsyst software[ ]. a. pvsyst software pvsyst software[ ] is used to design different types of solar application systems like dc grid, grid connected, standalone and dc pumping systems. different solar pv module, battery and converter manufacture database for designing the system as it is included in the software package. location details for the area of the experiment can be added with the help of software like meteonorm, retscreen etc[ ]. this software helps to design the system with respect to the load and available area. it also helps to analyze the annual, monthly and weekly production and performance of the designed system. b. data for designing a standalone system, the geographical data, solar pv module, battery database and monthly meteorological data for global radiation and temperature are international journal of engineering research & technology (ijert) issn: - www.ijert.orgijertv is (this work is licensed under a creative commons attribution . international license.) vol. issue , april- required. the angle of tilt can be adjusted to get maximum irradiance on the solar pv module table shows the location details of thiruvanathapuram for the study. table shows the meteorological data of the site. table location details name of the site thiruvanathapuram latitude in degrees . n longitude in degrees . e altitude m azimuth tilt yearly irradiation yield kwh/m c. standalone system the standalone system consisting of a solar pv module, a charge controller and a battery. in some cases extra diesel generator back up is used and it will be depends upon the type and behavior of the load[ ]. in standalone system, solar pv modules generates the current and it helps to meet the load demand during daytime. at the same time, some generated current is used to charge the battery and it is helpful to meet the load demand during night time. charge controllers are used to control the flow of charging and discharging current into and from the battery[ ]. figure . shows the standalone system of solar pv system. fig. standalone solar pv system d. solar pv module table shows the specification of the solar pv module used for the study. table panel specification name of the manufacturer emmvee photovoltaic power pvt. ltd model es- p g type polycrystalline rated power wp module efficiency at stc . % open circuit voltage voc . v short circuit voltage isc . a rated voltage vmpp . v rated current impp . a dimension (lxbxt) x x mm e. battery table shows the specification of battery used for the study. table panel specification name of the manufacturer exide classic model opzs solar type lead acid, tubular nominal voltage v nominal capacity ah internal resistance . ohm coulombic efficiency . % dimension (lxbxh) x x mm iii. different panel arrangements in order to get maximum performance from the solar pv modules, the panels should be free from partial shading losses. so the arrangement of solar pv modules are a major concern to meet the demand of the consumer. table meteorological data from meteonorm interval global horizontal radiation kwh/m .mth diffused horizontal radiation kwh/m .mth beam horizontal radiation kwh/m .mth beam normal radiation kwh/m .mth global inclination kwh/m .mth ambient temperature c wind velocity m/s january . . . . . . . february . . . . . . . march . . . . . . . april . . . . . . . may . . . . . . . june . . . . . . . july . . . . . . . august . . . . . . . september . . . . . . . october . . . . . . . november . . . . . . . december . . . . . . . year . . . . . . . international journal of engineering research & technology (ijert) issn: - www.ijert.orgijertv is (this work is licensed under a creative commons attribution . international license.) vol. issue , april- a. single layer solar pv system three solar panels are arranged in a single layer with a tilt of . each panels are arranged without affecting the partial shading issues. the panels are facing towards the south pole. fig. shows the d arrangement of solar pv panels and fig. shows the side view of the solar pv panels. fig. d arrangement of solar pv panels fig. side view of solar pv panels b. single layer solar pv system with solar tracking system in this case, the single layer solar pv panels are connected with solar tracking systems. panels are facing towards the south pole direction. for tracking, the area required will be higher in order to avoid the partial shading losses. fig. shows the d arrangement of solar pv panels with solar tracking system. fig. d arrangement of solar pv panels with solar tracker c. three layer solar pv panels with solar tracking system three solar pv panels are arranged in a step like manner. each panels are arranged without causing any partial shading with each other. for obtaining maximum energy, panels are separately connected with solar tracking systems. panels are facing towards the east pole direction. fig. shows the d arrangement of a three layer solar pv panels with solar tracking system. fig. shows the front view of a three layer solar pv panel incorporated with solar tracking system. fig. d arrangement of a three layer solar pv panels with solar tracker fig. front view of a three layer solar pv panels with solar tracker iv. comparison of different solar panel arrangement although the study clearly demonstrate the maximum energy generation for the multi layer solar panel system as compared to single layer, one should be careful about the cost economics involved for such a system. a. single layer solar pv system in the first case we were considered a single layer panel system which have to produce a cumulative energy of . kwh/day. for that w solar panels and placed in the direction facing south with a tilt angle of . here three modules of w solar pv panels are used to produce an energy of . kwh/day. we know that as the number of modules increases, both the cost and area required was also increased. the detailed analysis about the performance and cost implication of the solar panel is shown in table . b. single layer solar pv system with solar tracking system in the case of single layer solar pv system with solar tracking system the same w solar panels are used and international journal of engineering research & technology (ijert) issn: - www.ijert.orgijertv is (this work is licensed under a creative commons attribution . international license.) vol. issue , april- placed in the direction facing south with a tilt angle of which was arranged in single layers. in order to produce an energy of . kwh/day modules of w solar pv panel are used. solar tracking systems are incorporated with each solar modules to extract maximum power available in the atmosphere. the detailed analysis about the performance and cost implication of the solar panel is shown in table . table comparison of different solar pv panel arrangements *cost of cent of land is taken as rs. , /- c. three layer solar pv panels with solar tracking system in the case of three layer solar pv module with solar tracking system, the same w solar pv modules and placed in the direction facing east which was arranged in three layers. in order to produce an energy of . kwh/day modules of w solar pv modules are used. here the panels were arranged one above the other without affecting shading losses. the system gives maximum energy from these modules all the time. this arrangement will not cause any partial shading on the second and third layer solar panels. the detailed analysis about the cost implication of the solar panel is shown in table . v. conclusion electricity generation has now become a major challenge for a country like india with rising fuel price and worsening air pollution. generating electricity using pv panels is a potential solution to the current energy crisis faced by india as it is renewable and climate friendly. in large urban cities there was not enough roof top space for installation of solar pv panels. in this paper, we had compared different panel arrangement that will minimize the floor area and maximize power generation through tracking the sun. in the case of single layer solar pv panel the area required to generate . kwh/day energy was around . m . so the land cost will be higher as compared with the three layer system. in single layer solar pv module with tracking system, the area required will be more as compared to the single layer solar panel and three layer system. from table , the land cost for the installation of a three layer solar panel is found to be low and the production from the system will be higher. the main disadvantage of the system was shading losses. the area required for the system is comparatively low. in order to get maximum output, less shading losses, less land area requirement, we use solar tracking techniques along with the three layer solar panel system. acknowledgment the authors would like to thank management of amal jyothi college of engineering, kanjirappally, kerala, india for providing all facilities to write this paper on solar panel arrangement. references [ ] http://www.indianpowersector.com/about, accessed on september . [ ] raman.p, murali.j, sakthivadivel.d, vigneswaran,v.s, "oppurtunities and challenges in setting up solar photovoltaic based micro grids for electrification in rural areas of india," renew. sustain, energy rev. ( ), - , . [ ] p.sharma, t.harinarayana, “enhancement of energy generation from two layer solar panels,” in international journal of energy and environment engineering, springer, , pp. . . [ ] http://www.pvsyst.com/images/pdf/pvsyst_tutorials.pdf, accessed on march . [ ] ahmed hosne zenan, sanjana ahmed, md. khalilur rhaman and mosaddequr rahman, „a multilevel solar panel system for urban areas', th ieee photovoltaic specialists conf. ( th ieee pvsc), - june tampa, florida, usa. [ ] chetan singh solanki, solar photovoltaics:fundamentals, technologies and applications, phi learning pvt ltd. . [ ] meinel, a. b. and meinel, m. p., applied solar energy, an introduction, addison-wesley, reading, ma, . [ ] roger a messenger and jerry ventre., photovoltaic systems engineering., nd edition. crc press llc, . single layer single layer with solar tracking system three layer with solar tracking system area required (m ) . . . land cost* (rs.) , , , technology si-poly si-poly si-poly panel wattage (w) no. of modules energy generated (kwh/day) . . . investment on system (rs.) , , , system production (kwh/year) total expenditure (rs.) , , , international journal of engineering research & technology (ijert) issn: - www.ijert.orgijertv is (this work is licensed under a creative commons attribution . international license.) vol. issue , april- uncovering pakistan’s environmental risks and remedies under the china-pakistan economic corridor trend editorial uncovering pakistan’s environmental risks and remedies under the china-pakistan economic corridor shahzad kouser & abdul subhan & abedullah received: august /accepted: december /published online: december # springer-verlag gmbh germany, part of springer nature abstract the china-pakistan economic corridor (cpec) is a journey towards economic integration of eurasia. the cpec contains us$ billion investment projects on energy, infrastructure, and other development projects in pakistan. however, cpec could enhance climate change vulnerabilities for the faltering economy of pakistan due to its three possible environmental risks and repercussions. its major environmental concern is related to energy projects as three quarters of the newly planned energy will be generated from traditional coal-fired power plants. traditional coal power plants are the major contributors to co emissions and smog, which ultimately lead to global warming and climate change. its second important environmental concern is linked with massive tree cutting for the construction of various road networks from kashghar, china, to gwadar, pakistan. tree cutting leads to enormous concentration of co emissions along the road networks. vehicle trafficking is its third important environmental threat. karakorum highway is expected to carry up to trucks per day that will release up to . million tons of co . despite all the environmental risks, the cpec enables pakistan to manage energy crisis and upgrade aging infrastructure. however, if appropriate remedial measures are not taken to diminish environmental risks, pakistan will be among major contributors to co emissions, and its rank will be worsen in global climate risk index, after completion of this project. therefore, it is very crucial to assess possible environmental impacts of cpec projects regarding energy, infrastructure, and transportation. furthermore, scientists from both countries should collaborate to manage the environmental repercussions of cpec projects. keywords cpec . environmental risks . energy . infrastructure . china . pakistan dear editor, the china-pakistan economic corridor (cpec) is a frame- work of regional connectivity. one belt one road initiative comprises of two trade connections: silk road economic belt and maritime silk road for the economic integration of eurasia. the cpec is the part of silk road economic belt and was launched in . the cpec contains us$ billion projects on energy, infrastructure, and other development pro- jects in pakistan (cpec ). it is considered a game chang- er for the faltering economy of pakistan as it is predicted to accelerate country’s economic growth at . % during the period of – (mirza et al. ). it is further predicted that cpec will create around , new jobs in pakistan by expediting mineral exploration, agricultural development, it revolution, communication networks, trade, and investment till (the news ). the cpec is also important for china’s economy as it will boost trade of chinese products by providing the shortest route to the markets of middle east, africa, and europe (khursheed et al. ). moreover, china will get the opportunity to develop its north-western territory xinjiang. in addition to economic benefits, the cpec has huge po- tential to address climate risks and environmental problems of pakistan. pakistan ranks seven among top ten climate change- vulnerable countries in the long-term global climate risk index (eckstein et al. ). moreover, the country is facing multidimensional challenges of climate change such as floods, droughts, heat waves, diseases, and increase in poverty and hunger (nabi et al. ). in contrast to put more stringent measures on environmental factors in the implementation of development projects, environmental impact assessment responsible editor: eyup dogan * shahzad kouser drskouser@comsats.edu.pk department of economics, comsats university islamabad, park road, islamabad, pakistan pakistan institute of development economics, islamabad, pakistan environmental science and pollution research ( ) : – https://doi.org/ . /s - - - http://crossmark.crossref.org/dialog/?doi= . /s - - - &domain=pdf http://orcid.org/ - - - mailto:drskouser@comsats.edu.pk (eia) has been ignored in the formulation of cpec projects. recent studies have warned that the cpec investments shall have direct adverse impacts on pakistan’s water, air, and bio- diversity (huang et al. ; zhang et al. ). the possible environmental concerns may drastically reduce the cpec’s potential benefits. one of the major environmental concerns of the cpec is related to energy projects in pakistan. to encounter energy crisis in the country, the cpec’s major investment, us$ billion, is allocated to energy projects, and three quarters of the newly planned energy will be generated from traditional coal-fired power plants in sindh (thar-i and thar-ii coal pow- er plants), punjab (sahiwal and salt range coal power plants), and balochistan (hub and gwadar coal power plants) prov- inces (cpec ). on the fact, traditional coal power plants are the major contributors to co emissions and smog, which ultimately lead to global warming and acid rain (ucsusa ). already seasonal smog has engulfed large areas of punjab and sindh provinces, and it has resulted in many fatal road accidents due to zero visibility and hospital admissions every year. envision, what will happen to the environment of these provinces when coal power plants start their full opera- tion (ali ), as coal fires along with automobile exhausts and burning of agricultural wastes are three major sources of smog (stanley ). further, poor air quality in these areas will result in growing cases of asthma, lung tissue damage, bronchial infection, and heart attack. greenhouse gas (ghg) emissions coming from coal-fired power plants can be re- duced up to – % by adopting ultra-supercritical coal tech- nology that helps to convert ghgs or particulate matter into supercritical fluids before releasing to the atmosphere (myllyvirta ). besides, supercritical fluids can be used to make acids, which are used as a raw material in different industries like pharmaceutical industry (kern ). the up- front cost of this technology is – % higher than traditional coal-fired power plants (power technology ), but its life span is – years more than traditional technology (kumar et al. ). china has also switched to this modern technol- ogy years back, after suffering from huge health burden due to polluted gray skies in six cities (ali ; yu and abler ). under the cpec, % of energy investment is targeted on renewable energy generation alternatives such as hydro, solar, and wind power projects to avoid greenhouse gas emissions in the country (cpec ). however, this is high time either to redirect most of cpec investment in re- newable energy projects to abridge energy gaps as pakistan has huge potential for these environmentally sustainable solu- tions or to at least switch to supercritical coal technology. another major environmental concern of cpec is linked with cutting down trees on large scale for the construction of various road networks in pakistan. the cpec road networks can be divided into northern section and three other align- ments, western, eastern, and central, which start kashghar in the western part of china and end in pakistan through gwadar, balochistan (cpec ). more than , fruit or non-fruit/forest trees have been chopped down in abbottabad, nowshera, lower dir, swabi, mardan, and malakand districts in (sadaqat ; sdpi ). a tree can absorb pounds of co per year and can play important role to mitigate risks of climate change (co measurement specialists ). after massive cutting, million pounds of co were not absorbed by trees in these districts in and are still accumulating in the atmosphere. these districts are already at high risks of climate change that appears in the form of increased temperature, droughts, soil erosion, untimely rains, and glacier melting that ultimately lead to extreme flooding. nowshera, lower dir, swabi, mardan, and malakand are previously the most vulnerable districts to mon- soon flooding (ali ). tourism industry of these districts has also badly affected. afforestation is the only remedy to protect biodiversity and deteriorated natural environment. it is required to plant eight trees as a reparation for an uprooted one (sadaqat ), besides compensating owner of the land with reasonable standing value of each tree. current plantation drive needs to be more rigourous in terms of tree selection and monitoring. vehicle trafficking is also an important environmental threat under cpec in the northern areas of pakistan. after the completion of road networks under cpec, the karakorum highway is expected to carry up to trucks per day that release up to . million tons of co on the way to gwadar (qazibash ). co emissions and particulate matter will change the local climate by deteriorating the air quality. air pollution has both acute and chronic health effects and contributes to increase morbidity and hospital admissions. increased co emission will drastically melt the glaciers and will increase flash floods. in baluchistan, sudden and unexpected flood has affected , people, with the loss in property and livelihood (who ). emissions of co and particulate matter can be combated through adopting the fol- lowing measures such as improving the aerodynamic charac- ter of vehicles; switching to alternative fuels e.g., biodiesel; improving road infrastructure; revising maximum weights and dimension of heavy-duty vehicles under european molecular system (ems), and truck platooning (linking of two or three self-driving trucks in convoy). however, ems has maximum effect to combat co emissions (eama ). these mea- sures have been proved to be successful in all adopted coun- tries such as denmark, finland, the netherlands, and sweden, while successful tests are underway in belgium, germany, and spain (eama ). nonetheless, catalytic converters suggested by earlier studies can change only the ghgs from unstable to stable form (catalytic converts ), despite ex- pensive technology and short life span. another possible rem- edy to reduce co emissions is the employment of electric vehicles to ensure eco-friendly corridor. environ sci pollut res ( ) : – despite all the environmental risks, the cpec enables pakistan to manage energy crisis and upgrade aging infra- structure. however, if appropriate remedial measures are not taken to diminish environmental risks, pakistan will be among major contributors to co emissions, and its rank will be worsen in global climate risk index, after completion of this project. therefore, it is very crucial to assess possible environ- mental impacts of cpec projects regarding energy, infrastruc- ture, and transportation. furthermore, scientists from both countries should collaborate to manage the environmental re- percussions of cpec projects. references ali m ( ) peshawar among districts most vulnerable to monsoon floods. dawn. retrieved from https://www.dawn.com/news/ ali m ( ) pakistan’s quest for coal-based energy under the china- pakistan economic corridor (cpec): implications for the 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http://www.emro.who.int/pak/pakistan-infocus/floods-in-balochistan.html 	uncovering pakistan’s environmental risks and remedies under the china-pakistan economic corridor 	abstract 	references a triboelectric nanogenerator based on cosmetic fixing powder for mechanical energy harvesting xia et al. microsystems & nanoengineering ( ) : microsystems & nanoengineering https://doi.org/ . /s - - - www.nature.com/micronano a r t i c l e op e n a c c e s s a triboelectric nanogenerator based on cosmetic fixing powder for mechanical energy harvesting kequan xia , yue chi , jiangming fu , zhiyuan zhu , hongze zhang , chaolin du and zhiwei xu abstract in this work, we use commercial powder particulates (a cosmetic fixing powder) as triboelectric materials for constructing a triboelectric nanogenerator (cfp-teng). through finger pressing, the cfp-teng generated approximate open-circuit voltage, short-circuit current, and maximum power density values of v, µa, and . μw/cm , respectively. thirty-seven commercial blue leds can be easily lit up by the cfp-teng. moreover, this teng, which was designed as a novel palette structure for harvesting mechanical energy from bicycle motion, serves as a self-powered bicycle speed sensor. in addition, the cosmetic fixing powder can be used as an effective material to enhance the triboelectric property of skin. this study provides an effective method for developing a cost-effective teng without the use of complex surface micro-/nano-texturing. introduction the global energy crisis is becoming increasingly severe with the fast-paced growth of the global economy – . moreover, with the continued acceleration of human civilization, exhaustion of fossil energy in the first half of the twenty-first century is expected , . renewable energy for electricity generation has been considered a means of solving the energy crisis – . solar energy, tidal energy, mechanical motion, and thermal changes are all con- sidered potential forms of energy that are convertible into electrical energy in the environment. among these, mechanical energy is the most extensively distributed type, as it occurs in diverse forms , . daily activities such as walking, running, cycling, and even tiny facial expres- sions (for example, smiling and crying) are accompanied by mechanical distortions, suggesting that the human body constitutes a pivotal means of mechanical power generation , . however, it is difficult to apply traditional electromagnetic induction generators for harvesting mechanical energy from the surrounding environment (human daily activities, etc.). in , prof. zhonglin wang (georgia institute of technology) proposed the first-ever triboelectric nano- generator (teng), which converts mechanical energy from the surrounding environment into electrical energy on the basis of the triboelectric effect – . during the past few years, the teng has received considerable attention and has been widely applied to multidisciplinary fields owing to its outstanding output performance, sus- tainable power output, and ease of integration – . sev- eral materials (for example, pdms, kapton, al, and teflon, each with its own merits and demerits) have been applied to the construction of tengs – . although silica-based powder is also used as one of the triboelectric pair , the output voltage is relatively low (~ v). the triboelectric substances proposed for teng construction should (ideally) be low cost, yield rapidly self-forming films, be processable without the need for cumbersome micro-/nano-processing, and (if possible) be readily available. in this work, we propose a novel concept of a powder teng that uses powder particulates (for example, © the author(s) openaccessthisarticleis licensedunderacreativecommonsattribution . internationallicense,whichpermitsuse,sharing,adaptation,distributionandreproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the creative commons license, and indicate if changes were made. the images or other third party material in this article are included in the article’s creative commons license, unless indicated otherwise in a credit line to the material. if material is not included in the article’s creative commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. to view a copy of this license, visit http://creativecommons.org/licenses/by/ . /. correspondence: zhiyuan zhu (zyzhu@zju.edu.cn) or zhiwei xu (xuzw@zju.edu.cn) ocean college, zhejiang university, zhejiang, china nanjing electronic devices institute, jiangsu, china () :,; () :,; () :,; () :, ; www.nature.com/micronano http://creativecommons.org/licenses/by/ . / mailto:zyzhu@zju.edu.cn mailto:xuzw@zju.edu.cn cosmetic fixing powder) as triboelectric materials for fabricating a triboelectric nanogenerator (cfp-teng). this fabrication, which is realized without the use of surface micro-/nano-texturing techniques that rely on expensive equipment and complex technology, may drive the large-scale application of tengs in multidisciplinary fields. in our work, this powder and teflon tape were used as the triboelectric pair. the cfp-teng can, through finger pressing, produce approximate open-circuit vol- tage, short-circuit current, and power density values of v, µa, and . μw/cm , respectively. thirty- seven commercial blue leds, which were assembled into the word “zju”, could be lit up by the cfp-teng. in addition, this teng, which was designed as a novel pal- ette structure to harvest mechanical energy from bicycle motion, serves as a self-powered speed sensor. in addition, the cosmetic fixing powder can be used as an effective material to enhance the triboelectric property of skin, which is significant for the development of a human- based teng. results the design and fabrication process of the cfp-teng device is schematically presented in fig. . first, a sheet of paper was cut into two pieces of paper substrate (size: cm × cm), as shown in fig. a. a piece of copper tape ( cm × cm) was then pasted onto the paper surface (see fig. b). subsequently, teflon tape was pasted onto the surface of the copper tape, thereby forming the top sec- tion of the teng, as shown in fig. c. another paper substrate was obtained by pasting the double-sided tape onto the paper substrate surface, as shown in fig. d, and then attaching the copper to the surface of the tape. afterward, the cosmetic fixing powder was applied onto the glue side of the copper tape. excess powder was then removed by air blowing, thereby forming the bottom section of the teng (see fig. e, f). a piece of poly- ethylene terephthalate (pet) film served as the supporting structure for assembly of the teng, as illustrated in fig. g. figure a, b shows photographs of the cfp-teng (one unit) and the stacked cfp-teng. representative scan- ning electron microscopy images showing the surface of the teflon tape and cosmetic fixing powder layer are stickinga b c g d e f h sticking assembling gum ptfe copper paper pet double-side tape powder foundation pr es sin g sticking sticking fig. preparation process of the cfp-teng a teng μm μm stacked teng b c d fig. images of the device and triboelectronic surfaces. photographs of the a cfp-teng unit and b stacked cfp-teng. sem image of the c teflon tape surface and d cosmetic fixing powder layer surface xia et al. microsystems & nanoengineering ( ) : page of presented in fig. c, d. a mechanical vibrator was used to activate the cfp-teng. the top and bottom of the teng were affixed to the pressing surface of the vibrator and a flat panel, respectively. the respective electrical output signals were then measured with a digital oscilloscope. the working principle of the cfp-teng is schemati- cally illustrated in fig. . when teflon tape is in contact with cosmetic fixing powder, electron transfer from the powder layer to the tape (fig. a). a latent electrical dif- ference is expected with separation of the tape from the powder. this type of latent difference drives the electron flow via the external loads from the top cu foil to the bottom cu foil. this flow screens the positive triboelectric charges available on the paper, thereby producing an output current signal (fig. b). a new electrical equili- brium is expected at the largest separation in a complete contact–separation cycle (fig. c). subsequent to this equilibrium, contact between the teflon tape and the cosmetic fixing powder layer is re-established, leading to an imbalance between the stimulated charges on the cu electrodes. this imbalance results in electron flow back to the top cu foil, thereby producing a reversed output current signal (fig. d). when full contact between the tape and paper is re-established, the cfp-teng reverts to its initial position, as shown in fig. a. to understand this mechanism, the latent distribution is simulated with comsol multiphysics software. an open-circuit a releasing r r r r i i pressing – – – – – – – – copper teflon tape gum cosmetic fixing powder approaching separating b d e (i) (ii) (iii) c fig. schematic and modeling analysis of the device. a–d working principle of the cfp-teng. e numerical calculations (as assessed with the help of comsol) of the potential distribution across teng electrodes, at each step (i–iii), subjected to open-circuit conditions (the voltage unit is volts) xia et al. microsystems & nanoengineering ( ) : page of scenario is considered for the three positions of the one- unit cfp-teng (see fig. e). an adjustable resistor ( kΩ to gΩ) was used as the external load of the fabricated tengs, and the electronic voltage on the resistor was measured. the output current can be derived from the measured voltage and the total resistance. the voltage (under a gΩ load) and current (under a kΩ load) of the fabricated cfp-teng are v and . μa, respectively (see fig. a, b), when triggered by a mechanical vibrator (amplitude: ∼ cm, frequency: hz). for the reverse connection of the oscilloscope to the cfp-teng, the output voltage and current signals are inverted (as shown in fig. d, e), which indicates that the signals were generated by the cfp- teng. considering the mΩ probe of the oscillo- scope, the total resistance can be calculated by rt = r × mΩ/(r + mΩ), and the corresponding output performance of cfp-teng is further investigated by evaluating the output power associated with the voltage and current occurring at equivalent total resistances ranging from . kΩ to . mΩ (see fig. c). with increasing total resistance, the current amplitude decreases owing to a loss of resistance, whereas the vol- tage increases. in addition, an approximate maximum power density value of . μw/cm corresponding to a total resistance of ∼ mΩ (see fig. f) is obtained. in addition, the output performances with and without cosmetic fixing powder are compared in the supporting information. the electronic output performance of the cfp-teng, based on contact separation, exhibits a high dependence on the contact frequency, separation distance, and device size. figure a, b shows the dependence of the voc and isc values of cfp-teng on contact frequency for a given device size and separation distance of cm × cm and mm, respectively. moreover, the output voltage increases from to v when the contact frequency increases from to hz. nonetheless, the isc increases continuously from . to . μa when the contact frequency increases from to hz. the increase in the isc and voc values is attributed to the rapid induction and charge transfer resulting from the elevated frequency contact. figure c, d shows the voc and the isc values of the ( cm × cm) cfp- teng as a function of the separation distance. further- more, with increasing separation distance, the voc increa- ses slowly and then saturates, while the isc increases continuously. the voc and isc values corresponding to a contact frequency and separation distance of hz and mm, respectively, of tengs with varied sizes are shown in fig. e, f. as the figure shows, voc and isc increase with increasing device size. the substantial enhancement in the output is attributed to the augmented contact region. detailed discussions of the impact of the separation dis- placement and frequency on the electrical performance are provided in the supporting information. furthermore, a stacked cfp-teng is designed and manufactured to improve the output efficiency. the isc values of the stacked cfp-tengs with , , and units are , , and μa, respectively (see fig. g). the results revealed that the output current increases with increasing number of units. similarly, the stability of the cfp-teng is evaluated from the findings presented in a b c d e f v o lta g e ( v ) v o lta g e ( v ) c u rr e n t (μ a ) c u rr e n t (μ a ) c u rr e n t (μ a ) – – – – v o lta g e ( v ) p o w e r (μ w ) r v teng – – – – – – – time (s) time (s) total resistance (mΩ) time (s) time (s) total resistance (mΩ) fig. electrical output of the device. output voltage and current of the cfp-teng calculated using the a, b forward connection and d, e reverse connection. dependence of c the output voltage and current on the total resistance and f the power density on the total resistance xia et al. microsystems & nanoengineering ( ) : page of fig. h. in accordance with the experimental results, a stable output voltage from the cfp-teng is realized even after a -cycle external force test. according to a previous study , the human body pro- duces hundreds of watts through body movements. therefore, harvesting low-frequency power generated by human physical movements is considered a potential means of realizing self-powered wearable electronics. in this work, we demonstrate that a cfp-teng ( cm × cm) can be activated via finger pressing (see fig. f). as a b c d e f g h hz mm mm mm mm mm mm mm mm mm mm mm mm mm mm unit unit unit unit mm mm mm mm hz hz hz hz hz hz hz hz hz hz hz i s c (μ a ) i s c (μ a ) i s c (μ a ) v o c (v ) – – – time (s) time (s) time (s) time (s) time (s) time (s) time (s) time (s)time (s) i s c (a ) – – – – – v o c (v ) v o c (v ) v o c (v ) v o c (v ) – – – – – – cycles – – – – – – – fig. performance and stability of the device. approximate values of voc and isc at various a, b frequencies (cfp-teng size: cm × cm, maximum separation distance: mm), c, d separation distances (mechanical frequency: hz, cfp-teng size: cm × cm), and e, f cfp-teng sizes (working frequency: hz, separation distance of the teng: mm. g output current of the cfp-teng with various unit numbers. h stability verification of the fabricated cfp-teng via cycles of continuous operation xia et al. microsystems & nanoengineering ( ) : page of shown in fig. a, b, isc and voc reach approximate values of μa and v, respectively. when a match load of mΩ (equivalent total resistance: . mΩ) is connected to the cfp-teng, the max- imum output power, corresponding to an output voltage of v and current of . μa, is reached (see fig. c, d). the corresponding maximum output power ( . mw) and power density ( . μw/cm ) are adequate for various low-energy-consumption micro- electronic gadgets. we also performed tests aimed at determining the charging potential of the fabricated cfp-teng connected to a nf capacitor by means of a full-wave rectifier bridge. the results revealed that ∼ nc of charge is transferred in one cycle. discussion to demonstrate the potential of the cfp-teng as an energy source, a cm × cm cfp-teng was linked to commercial blue leds in series (as presented in fig. a–c). the results revealed that the assembly of these leds forming the word “zju” could be easily lit up by the teng. in addition, we propose a novel palette structure for harvesting the mechanical power associated with bicycle movement (see fig. a). moreover, the proposed structure can also monitor the bicycle speed. the corresponding output voltage of the device (under a gΩ load) can reach . , . , and . v for , , and r.p.m., respectively, as shown in fig. b–d. in addition, the a b c d e f v o c (v ) – – – – nc teng v – – – – c u rr e n t (μ a ) – – v o lta g e ( v ) v o lta g e ( v ) – i s c (μ a ) time (s) time (s) time (s) time (s) time (s) finger teng fig. electrical characteristics of the cfp-teng powered by physical movement (finger pressing). approximate a voc and b isc values of the cfp-teng; c output voltage and d current corresponding to a match load of mΩ (equivalent total resistance: . mΩ); e voltage of a nf capacitor linked to the cfp-teng by means of a full-wave rectifier bridge, indicating the quantity of charge transferred in one cycle; and f a cfp-teng triggered by finger pressing xia et al. microsystems & nanoengineering ( ) : page of output voltages subjected to different speeds are shown in fig. e. it is observed that the output voltage is approxi- mately linear to the speed. furthermore, we proposed a new application of a powder- enhanced skin-based teng. in detail, when the skin is made as the triboelectric layer, the output voltage can reach v, as shown in fig. a. when the skin is modified by cosmetic fixing powder, the output voltage can reach v, as shown in fig. b. according to the results, the cosmetic fixing powder can be used as an effective material to enhance the triboelectric property of skin, which is sig- nificant for the development of a human-based teng. a b c fig. driving capability of the device. a a cfp-teng connected in series with commercial blue leds (the inset shows a cm × cm teng); b, c commercial blue leds powered by finger pressing of the cfp-teng copper paper ptfe powder foundation v o lta g e ( v ) speed (r/min) ba e c d r/min r/min r/min v o lta g e ( v ) – – – v o lta g e ( v ) v o lta g e ( v ) – – – – – – time (s) time (s) time (s) fig. harvesting mechanical power associated with bicycle movement. a photograph of a bicycle with a teng (inset shows the palette structure of the teng); b–d output voltage signals corresponding to three movement states ( , , and r.p.m.). e the output voltages subjected to varied speeds xia et al. microsystems & nanoengineering ( ) : page of conclusions a novel concept of powder electronics that use powder particulates (a cosmetic fixing powder) as triboelectric materials for fabricating a teng is proposed in this work. the loose powder and teflon tape are used as the tribo- electric pair. the cfp-teng can generate approximate voc, isc, and maximum power density values of v, µa, and . μw/cm , respectively. stable output voltage from the cfp-teng is realized after a -cycle external force test. in addition, this teng, which was designed as a novel palette structure for harvesting mechanical energy from bicycle motion, serves as a self- powered speed sensor. furthermore, the cosmetic fixing powder can be used as an effective material to enhance the triboelectric property of skin. this work represents a significant step towards the large-scale production of tengs. materials and methods all materials are commercially available and used without further processing. acknowledgements this work was supported by the national natural science foundation of china (grant no. , grant no. , grant no. ) and the aeronautical science foundation of china (grant no. asfc- zc ). the author would also like to thank prof. yufeng jin and prof. min yu from peking university for their previous guidance. authors' contributions k.x. performed the experiment and wrote the paper. z.z. analysed the data and wrote the paper. y.c., j.f., h.z., c.d., and z.x. analysed the data. conflict of interest the authors declare that they have no conflict of interest. supplementary information accompanies this paper at https://doi.org/ . /s - - - . received: january revised: march accepted: march references . ren, x. et al. wind energy harvester based on coaxial rotatory 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mechanical energy harvesting 	introduction 	results 	discussion 	conclusions 	materials and methods 	acknowledgments the analysis of the performance of heating and the economical efficiency of the solar energy and gas heat pump procedia engineering ( ) – - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of ishvac-cobee doi: . /j.proeng. . . sciencedirect available online at www.sciencedirect.com th international symposium on heating, ventilation and air conditioning (ishvac) and the rd international conference on building energy and environment (cobee) the analysis of the performance of heating and the economical efficiency of the solar energy and gas heat pump hong haoa,*, junbin yaoa, guohui fenga, huating wenb a school of municipal and environmental engineering,shenyang jianzhu university, shenyang, china b china northeast architectural design & research institute co.,ltd , shenyang , china abstract the solar and gas heat pump heating system is a system that combines the gas heat pump and the solar heat pump driven by electricity. on the one hand, the system makes full use of the solar, and it is a real high-efficiency, energy-saving system. on the other hand, the system use natural gas as an energy source which can relieve the energy crisis, reduce environmental pollution and relieve the pressure of the grid. during the operation of the system, it will save operating costs due to the cheaper price of gas compared with electricity. therefore, the research of the solar and gas heat pump has a great sense of energy-saving and economical. © the authors. published by elsevier ltd. peer-review under responsibility of the organizing committee of ishvaccobee . keywords: zero energy building; dest; energy saving . introduction the solar and gas heat pump heating system is a system that combines the gas heat pump and the solar heat pump driven by electricity. on the one hand, the system makes full use of the solar, and it is a real high-efficiency, energy-saving system. on the other hand, the system use natural gas as an energy source which can relieve the energy crisis, reduce environmental pollution and relieve the pressure of the grid. during the operation of the system, it will save operating costs due to the cheaper price of gas compared with electricity. therefore, the research of the solar and gas heat pump has a great sense of energy-saving and economical. ` * corresponding author. tel.: + - . e-mail address: @qq.com © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of ishvac-cobee http://crossmark.crossref.org/dialog/?doi= . /j.proeng. . . &domain=pdf hong hao et al. / procedia engineering ( ) – since entering the st century there are more and more researches about the solar heat pump system. v badescu had a further study on the equipments in the solar heat pump heating system. the result shows that in the process of heating, if the volume of the device used to storage thermal increase, then the power of the compressor of the solar heat pump will increase, but the cop of the heat pump will decrease. r•yumrutas and others researched the characteristic of the operation in the solar heat pump with seasonal underground thermal storage device. the result shows that there are two aspects will influence the performance of the whole solar heat pump heating system. one of them is the thermal properties of soil. different soil has different thermal conductivity which will influence the experiment and get different results. another one is the size of the storage device. when the size is so small, it will not present the heating system. when the size is pretty big, the device of the system will be pretty complex. so the size should be controlled in a reasonable range. in the s, our country has built the earliest solar hot water project. tianjin university and beijing institute of architectural design designed the first solar water heater with natural circulation by researching a series of solar water heaters and built a bathroom with this technology which became an example of solar hot water heating. from s, our country started the research about the gas heat pump. the first institution who started the research first in our country is thermal research institute, tianjin university. their research conducted a series of feasibility analysis for the application of the gas heat pump. they also made a series of experimental studies about the gas heat pump which laid a solid foundation for the development of the gas heat pump. . methods this paper builds a system of solar energy heat pump which is driven by the gas engine , calculates and chooses proper equipments for the system,then simulates some specific parameters like the number that the compressor turns,rotate speed of the engine,the cop of the system and the amount of the heat release of the condensation on it by trnsys and simulink. shenyang is located in northeast cold zone in china, the heat load in winter is bigger than the cooling load in summer. so it’s necessary to choose the model of the ground heat pump on the basic of the annual heat load of the building. if we want to meet the heat and cooling require, we can not decrease the capacity of the gas heat pump system in the design condition because of the instability of the solar in the process of heating. what we should do is that we should leave a certain amount of capacity to assure the performance of the heating system. so we should assume one of the most unfavorable conditions first like that there is no solar half a day, then select the type of the gas heat pump. the maximum heat load is kw, the design heat load of the gas heat pump is % of the whole heat load kw. we choose the gas heat pump designed by rand air conditioning company in this paper. the specific parameters of the system are shown in table . table gas heat pump parameters. type gshp-c d heating effect/kw input power of the refrigeration/kw . refrigerating effect/kw input power of the heating/kw . water flow of the evaporator when heating/ m /h pressure loss ≤ water flow of the condenser when refrigerating/ m /h pressure loss ≤ the main equipments of the solar and gas heat pump are solar collector and storage model, gas engine model, waste heat recovery model and heat pump model. we use trnsys to simulate the solar collector and storage model in the system and set the temperature of the water in the buffer tank to - . the other parameters like hong hao et al. / procedia engineering ( ) – the gas engine, waste heat recovery system, heat pump will be simulated by matlab. regarding the change of the temperature of the water in the solar storage tank as the heat source of the evaporator and choosing r a as the cycle working fluid of the heat pump. the relevant physical parameters of the cycle working fluid are shown in reference . the main simulation model of the system is shown in fig. . fig. . a system model in matlab. . results tables and illustrations fig. . relationship between compressor rotation speed and condensation heat release. hong hao et al. / procedia engineering ( ) – figure shows the change of the condensation heat release with the change of the number of the compressor rotation number under the condition that the evaporation temperature of the solar and gas heat pump is , the condensing temperature is . the condensation heat release will increase with the increase of the compressor rotation speed. the compressor rotation speed is one of the factors which will influence the condensation heat release. in order to get more condensation heat release we can increase the compressor rotation speed which means that we should increase the engine speed of the gas engine by control the gas volume which will enter the engine. considering the stability, security, using time and economy of the heating system, we can not increase the gas volume unlimitedly we should control the amount of gas in a certain range. fig. . relationship between compressor rotation number and cop. figure shows the change of the cop of the system with the change of the number of the compressor rotation number under the condition that the evaporation temperature of the solar and gas heat pump is , the condensing temperature is . from the graph of the variation we can draw a conclusion that the cop of the system will decrease with the increase of the compressor rotation number. that is because that when we increase the compressor rotation number, we should increase the use of nature gas which means that the energy consumption of the system will increase at the same time. according to the analysis, we should make the compressor rotation number in a proper range in order to get higher cop. if the compressor rotation number is pretty big, the energy consump tion of the system will increase which will influence the performance of the system. when the compressor rotation number is small enough, we will get a higher cop, but we can find that the condensation heat release will decrease which means that we can not assure the comfort of the heating system. therefore, we can learn that when the compressor rotation number in the range of - rev / min, the performance and the comfort of the solar and gas heat pump heating system are best from the fig and fig . in a word, we should control the compressor rotation number in the range of - rev/min by controlling the use of the natural gas in the operation of the system. hong hao et al. / procedia engineering ( ) – fig. . relationship between engine rotation speed and cop. figure shows the change of the cop of the system with the change of the engine rotation speed under the condition that the evaporation temperature of the solar and gas heat pump is , the condensing temperature is . compared with the figure , the range of the cop is pretty big which is because of the recover of part of the waste heat of engine and the performance of the system is improved. fig. . comparison of three kinds of gas hot economic. the fig. is gained in the condition that the price of the electricity is . yuan/(kw h). we can find that when the using time is short, using the gas boiler for heating is more economical. but when the using time is long and the price of the natural gas is low, the gas cogeneration heating system is more suitable. when the using time is long and the price of the natural gas is high, the gas heat pump is more economical. in shenyang, the heating time is from november to march, means days,or hours.and the price of the natural gas is . yuan/m . we can know that shenyang is in the area that the gas heat pump is more economical, which means that the gas heat pump is more suitable in shenyang. hong hao et al. / procedia engineering ( ) – fig. . three kinds of gas heating economic zone. the fig. gives the economic distribution of the gas heating withe the change of the price of electricity and the natural gas. we assume the hour of heating is . we can see that the gas boiler is more economical the the price of the natural gas and the electricity are low. the gas cogeneration heating system is more economical when the price of the electricity is high and the price of the natural gas is low. when the price of the electricity and the natural gas are all high, the gas heat pump heating system is the most economical. in shenyang, the price of the electricity is . yuan, we can see that the gas heat pump heating system is more economical easily. . equations ( )for gas-fired boiler and gas heat pump, the annual operating costs z of each of the heating capacity is:\ ( ) ( )for the gas cogeneration system, the generating income should be cut from the cost, therefore: ( ) .names and units the system investment of each of the heating capacity, yuan/kw; the depreciation rate which is the reciprocal of the system uses life; b the primary energy rate of the system; the price of the natural gas, yuan/m ec the price of the electricity, yuan/(kw h) hong hao et al. / procedia engineering ( ) – .discussion the solar and gas heat pump heating system is a system that combines the gas heat pump and the solar heat pump driven by electricity. on the one hand, the system makes full use of the solar, and it is a real high-efficiency, energy-saving system. on the other hand, the system use natural gas as an energy source which can relieve the energy crisis, reduce environmental pollution and relieve the pressure of the grid. during the operation of the system, it will save operating costs due to the cheaper price of gas compared with electricity. therefore, the research of the solar and gas heat pump has a great sense of energy-saving and economical. .conclusion ) from the simulation analysis, we can know that the rotate speed of the compressor is in the range of - r/min, the heating performance and the comfort of the solar and gas heat pump heating system are best. the heat release of the system and the rotation number of the compressor are all high at the same time. ) according to the price of the natural gas and electricity in shenyang, we analyze the gas boiler, gas heat pump and the gas cogeneration heating system and draw a conclusion that the gas heat pump heating system is the most economical system in shenyang. ) from the comparison of the three different systems, we can know that when the heating system is short, the gas boiler is economical, even though the consumption of source and the price of the heating source are high. the advantage of the gas heat pump and the gas cogeneration heating system will show when the heating time is long. acknowledgements this research was supported by national twelfth five-year plan for science and technology ( baj b ). references [ ] e.b. penrod, k.v. prasanna, procedure for designing solar-earth heatpumps, j. heating, piping and air conditioning. 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[ ] z.j. xu, independent internal combustion engine heat pump system and control characteristics of the experimental study, ph.d. thesis, tianjin university, china, . jps volume issue cover and front matter volume part april british journal of political lence cambridge university press british journal of political science editor: a n t h o n y k i n o , professor of government, university of essex editorial board brian barky, university of british columbia h u g h b e r r i n g t o n , university of newcastle upon tyne ivor c r e w e , university of essex robert d o w s e , university of exeter f r e d . i. g r e e n s t e i n , princeton university j a c k h a y w a r d , university of hull m a u r i c e k o c a n , brunei university a rend l i j p h a r t , university of leiden samuel c. patterson, university of iowa r o b e r t d. putnam, university of michigan e d i t o r i a l policy the british journal of political science is an independent journal, whose policy is set by its editorial board. it is committed to no methodological orthodoxy over and above the normal canons of scholarship: clear and consistent use of words, logical and mathematical validity, and the use of appropriate evidence to substantiate empirical statements. contributions are invited in all fields of political science, including political philosophy and political sociology. work addressed to problems of general significance to students of politics will be published whatever the period(s) or place(s) drawn upon for evidence. i© cambridge university press p e r m i s s i o n s for permission to reproduce material from british journal / political science, please apply to the london or new york office of cambridge university press. isi tear service, chestnut street, philadelphia, pennsylvania , u.s.a. is authorized to supply single copies of separate articles for private use only. s u b s c r i p t i o n s british journal of political science is published quarterly in january, april, july and october. the subscription price of a volume (which includes postage) is £ . net in uk (us $ . in usa and canada) for institutions; £ . 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(iv) yearly average maps of solar radiation in azerbaijan energy and power , ( ): - doi: . /j.ep . . yearly average maps of solar radiation in azerbaijan fuad mammadov azerbaijan state oil acad emy, d. aliy eva ,baku, az , p hone-fax (+ ) , azerbaijan abstract due to his geographical location, climate condition and economica l in frastructure peculiarit ies azerbaijan is the most perspective region for renewable and a lternative energy sources’ application. today e xhaust fossil fue ls e xhaust stock equal to ~ b illion tone crude oil and , b illion m gas that concedes to middle east on the quantity. on the other hand the predictions show that till - years crude oil consumption in aze rbaijan will consist of - % and gas demand will be - % which can lead appreciable depletion of hydrocarbon stock subject to their e xpo rt. in this aspect it is necessary to notice that in ma jority of the regions of azerbaijan solar energy potentials consist of averagely - kw-hour/m (including some cases till kw-hour/ m in na khchivan autonomous republic). for applicat ion of solar energy objective evidence on solar energy potential is important. to solve practical tasks dealing with solar energy and to include its potential in azerba ijan energy balance long term measure ments should be carried out. development of solar cadastre of azerbaijan permits to estimate technically and economically benefic ial variants of solar energy potentials during solar energy plants building in diffe rent regions of the republic. by this purpose in azerbaijan solar energy potential map was firstly established. therefore during years measurements at weather stations located in the several zones of the republic have been carried out. here average annual amount of sunshine hours, direct, diffuse and albedo solar radiations were determined. on the base of the obtained results solar energy potential maps were prepared. i should notice that maps of azerbaijan solar energy potentials are to be published in this paper in first time. keywords solar radiation, sunshine hours, direct rad iation, diffuse rad iation, albedo rad iation . introduction mainly energy sector causes environmental pollution and formation of ha zardous gases leading green house effect in azerbaijan. gas emission per a person in azerbaijan consists of - ton. according to the pred ictions this showing for - will be - ton. such te mperature increasing happens majorly because of oil ( - % ) and gas ( - %) e xp loitation. prevention of further ecological problems and energy crisis can be rea lized only at the e xpense of alternative and renewab le energy sources. thus replace ment of the current fuel-energy sector into renewable energy sources will cause healthy life, natural safety, protection of flora and fauna. if we take into consideration that population azerba ijan live in absheron and the surrounding regions and already near years oil and gas have been e xtracted here, in this case ecology clean energy application has great importance. for the solution of the practical questions put forward in this field of information on solar energy of the region is very n ecessary . deve lop ment o f th e in forma t ion may induce new energy balance generation of azerbaijan. up t od ay t he we ll-kn o wn re s ea rch e rs e.m .sh ikh lin s ki, * corresponding author: fm_solarpower@yahoo.com (fuad mammadov) published online at http://journal.sapub.org/ep copyright © scientific & academic publishing. all rights reserved a.a.madatzadeh, v.m.madat zadeh, ch.a.shver, a.d.eyyu bov, sh.y. goychayli and other developed and established climate (te mperature of soil and air, prec ipitation, radiation and heat balance, cloudiness, snow cover, relative humidity and so on) of azerbaijan[ , , , , ]. though the deeds mentioned above, potential of renewable energy sources in none of the zones in the republic have been determined. so in the co mmunal build ings, houses, industry enterprises, in oil and power-engineering sector, there is a great dea l of energy consuming processes. that’s why the average annual or average seasonal renewable energy potentials of the republic should be known. sola r energy for the demanded power generation in industry sectors is to be certainly determined. only in the case of determining sunshine, direct, diffuse and albedo solar radiat ions’ average annual marks in those places solar themal and power stations can be built. though azerbaijan has rich solar resources and in this fie ld state progra m was signed in in the republic, none of database on solar energy potential for the country has been estblished. the neighboring countries, turkey, russia, iran[ , , ] have already processed their own solar energy potential maps. the first database on azerbaijan solar energy potential was shown in the resaerches carried out by dr, associate professor f.f.ma mmadov[ ]. at the result of the measurements realized bt the existing metereo logical stations in the republic till years and on the base of measure ments done in the latest years by us energy and power , ( ): - on the republic average annual ma rksof direct, diffuse and albedo solar rad iations have been determined. due to the obtained conclusions solar energy potential maps covering entirely the republic territory were established. . analysis of solar radiation measurements during the measure ments beside data of (e ight) main meteorologica l stations informat ion’s obtained from the mobile meteorologica l stations have been analysed. so the geographical coordinates of the region and relief we re defined. according to the re lie f p roperties azerba ijan is so variegated country. alongside mountains with - , in the country area there are pla ins, lowlands, regions below fro m the sea level. azerbaijan territory is divided into places consisting of the great caucasus and the little caucasus mountains. here a ir flo w enters the republic via the great caucasus, the litt le caucasus mountains and the caspian sea basin. both the south cyclone and the hot air currents formed by semitropica l anticyclone systems causes generation of the air current. th is factor influences on each zone in fa lling solar radiation distribution. in open air in aze rbaijan average annual inde x of direct solar radiat ion fa lling onto the horizontal surface increases fro m the direct ion of the northern to the south beginning fro m the sea level. on the mountainous regions solar radiation a mount is higher than other places. for a zerbaijan region the direct solar rad iation ( / mw ) fa lling onto the horizontal surface in open air and half c loudy weather condition have been given in the following maps. . solar radiation maps . . sunshine hours, non sunny days and direct solar radi ation maps average annual a mount of d iffuse solar rad iation in open air consists of / cmkkal− in the mountains amount of diffuse solar radiat ion decreases due to the diffusing particles. in the foothill regions at - m he ight diffuse solar radiat ion a mount is approximate ly / cmkcal , at - m height that’s / cmkcal . in the mountainous regions during cloudy weather diffuse solar radiation changes enough. for azerbaijan territory in both open air and half c loudy weather condition diffuse solar radiat ion ( / mw ) is changing as at the below. . . diffuse solar radi ati on maps initia lly landscape and surface cover types were determined for defining total and a lbedo solar radiations in azerbaijan territory. these are woodlands, mountains, plains, plateaus, lowlands, snow covers, water basins ( the caspian sea , la kes and water reservoirs, rivers). at the result of the measurements in several c limate zones of the republic correlat ion between average annual amount of total and albedo solar radiations and different height distinctions was determined and their graphics we re established. on the base of these graphics and conclusions total and albedo solar radiations map of the republic was developed. fi gure . amount of annual sunshine hours fuad m ammadov: year ly average m ap s of solar radiation in azerbaijan fi gure . amount of non sunny days a year fi gure . direct solar radiat ion falling on the horizont al surface in fair weat her energy and power , ( ): - fi gure . direct solar radiat ion falling on the horizont al surface in half cloudy weather fi gure . diffuse solar radiat ion in fair weather fuad m ammadov: year ly average m ap s of solar radiation in azerbaijan fi gure . diffuse solar radiat ion in half cloudy weat her . . total and al be do solar radiation maps fi gure . total solar radiat ion in fair weat her energy and power , ( ): - fi gure . total solar radiat ion in half cloudy weather fi gure . albedo solar radiat ion in fair weat her fuad m ammadov: year ly average m ap s of solar radiation in azerbaijan fi gure . albedo solar radiat ion in half cloudy weather . discussion and conclusions all maps were established on : scale in arcgis and arcview progra ms. the developed maps are so important for the energy sector of the republic. according to the decree signed by the president of a zerbaijan republic these maps are to be included to the azerbaijan national atlas within the energy potential sector. references [ ] shikhlinski e.m . atlas of the heat balance of azerbaijan. m oscow. p . [ ] m adatzadeh a.a., shikhlinski e.m . climate of azerbaijan. baku . p . [ ] shver ch.a., m adatzadeh v.m . climate of baku. leningrad . p . [ ] a.d.eyy ubov. climate of health-resort zone of azerbaijan. baku . [ ] goy chay li sh.y. ecolo gical p roblems of azerbaijan. baku . p . [ ] e.taşdemiro glu and r. sev er. m onthly and y early average map s of total and direct solar r adiation in turkey . solar ener gy . vol. . number . . p p . - . [ ] wind and solar climate atlas of russia. publishin g house by name a.i.vo ey kov. . p [ ] m .daneshy ar. solar radiation statistic in iran. solar ener gy . vol. . . . p p . [ ] m ammadov f.f. solar en er gy use in azerbaijan and modern solar ener gy p lant’s. baku, proqres, p . . 	 . introduction 	 . analysis of solar radiation measurements 	condition have been given in the following maps. 	 . solar radiation maps 	 . discussion and conclusions the potential of microwave heating in separating water-in-oil (w/o) emulsions sciencedirect available online at www.sciencedirect.comavailable online at www.sciencedirect.com sciencedirect energy procedia ( ) – www.elsevier.com/locate/procedia - © the authors. published by elsevier ltd. peer-review under responsibility of the scientific committee of the th international symposium on district heating and cooling. the th international symposium on district heating and cooling assessing the feasibility of using the heat demand-outdoor temperature function for a long-term district heat demand forecast i. andrića,b,c*, a. pinaa, p. ferrãoa, j. fournierb., b. lacarrièrec, o. le correc ain+ center for innovation, technology and policy research - instituto superior técnico, av. rovisco pais , - lisbon, portugal bveolia recherche & innovation, avenue dreyfous daniel, limay, france cdépartement systèmes Énergétiques et environnement - imt atlantique, rue alfred kastler, nantes, france abstract district heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. these systems require high investments which are returned through the heat sales. due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. the main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand forecast. the district of alvalade, located in lisbon (portugal), was used as a case study. the district is consisted of buildings that vary in both construction period and typology. three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). to estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. the results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than % for all weather scenarios considered). however, after introducing renovation scenarios, the error value increased up to . % (depending on the weather and renovation scenarios combination considered). the value of slope coefficient increased on average within the range of . % up to % per decade, that corresponds to the decrease in the number of heating hours of - h during the heating season (depending on the combination of weather and renovation scenarios considered). on the other hand, function intercept increased for . - . % per decade (depending on the coupled scenarios). the values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. © the authors. published by elsevier ltd. peer-review under responsibility of the scientific committee of the th international symposium on district heating and cooling. keywords: heat demand; forecast; climate change energy procedia ( ) – - © the authors. published by elsevier ltd. peer-review under responsibility of the scientific committee of the international conference on alternative energy in developing countries and emerging economies. . /j.egypro. . . . /j.egypro. . . - © the authors. published by elsevier ltd. peer-review under responsibility of the scientific committee of the international conference on alternative energy in developing countries and emerging economies. available online at www.sciencedirect.com sciencedirect energy procedia ( ) – www.elsevier.com/locate/procedia - © the authors. published by elsevier ltd. peer-review under responsibility of the organizing committee of aedcee. international conference on alternative energy in developing countries and emerging economies aedcee, ‐ may , bangkok, thailand the potential of microwave heating in separating water-in-oil (w/o) emulsions n.h. abdurahmana ; r.m.yunusa ; n.h. azharib; n.saida and z. hassana afaculty of chemical and natural resources engineering, university malaysia pahang-ump bfaculty of pure and applied sciences international university of africa, khartoum, sudan abstract with the increasing energy crisis and the drive to reduce co emissions, the mechanism of microwave heating is essentially that of dielectric heating. in this study, microwave demulsification method was investigated in a - % and - % water-in-oil emulsions with microwave exposure time varied from seconds to seconds. transient temperature profiles of water-in-oil emulsions inside a cylindrical container were measured. the temperature rise at a given location was almost horizontal (linear). the rate of temperature increase of emulsions decreased at higher temperature due to decreasing dielectric loss of water. results of this work shown that microwave radiation is a dielectric heating technique with the unique characteristic of penetration, fast, volumetric, and selective heating is appropriate and has the potential to be used as an alternative way in the demulsification process. microwave demulsification of water-in-oil emulsions does not require chemical additions. © the authors. published by elsevier ltd. peer-review under responsibility of the organizing committee of aedcee. keywords: demulsification, temperature profile, w/o emulsion. microwave heating, stability corresponding email: nour _ @yahoo.com available online at www.sciencedirect.com sciencedirect energy procedia ( ) – www.elsevier.com/locate/procedia - © the authors. published by elsevier ltd. peer-review under responsibility of the organizing committee of aedcee. international conference on alternative energy in developing countries and emerging economies aedcee, ‐ may , bangkok, thailand the potential of microwave heating in separating water-in-oil (w/o) emulsions n.h. abdurahmana ; r.m.yunusa ; n.h. azharib; n.saida and z. hassana afaculty of chemical and natural resources engineering, university malaysia pahang-ump bfaculty of pure and applied sciences international university of africa, khartoum, sudan abstract with the increasing energy crisis and the drive to reduce co emissions, the mechanism of microwave heating is essentially that of dielectric heating. in this study, microwave demulsification method was investigated in a - % and - % water-in-oil emulsions with microwave exposure time varied from seconds to seconds. transient temperature profiles of water-in-oil emulsions inside a cylindrical container were measured. the temperature rise at a given location was almost horizontal (linear). the rate of temperature increase of emulsions decreased at higher temperature due to decreasing dielectric loss of water. results of this work shown that microwave radiation is a dielectric heating technique with the unique characteristic of penetration, fast, volumetric, and selective heating is appropriate and has the potential to be used as an alternative way in the demulsification process. microwave demulsification of water-in-oil emulsions does not require chemical additions. © the authors. published by elsevier ltd. peer-review under responsibility of the organizing committee of aedcee. keywords: demulsification, temperature profile, w/o emulsion. microwave heating, stability corresponding email: nour _ @yahoo.com http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf n.h. abdurahman et al. / energy procedia ( ) – abdurahman.n.h et.al / energy procedia ( ) – . introduction a problem in mature oil fields is the sizeable amount of water accompanying the produced crude oil. water is also injected into the crude in course of steam treatment of producing wells or during de-salting operations. petroleum emulsions readily form from water/oil mixtures in turbulent flows or due to pressure gradients in reservoir pores, in the chokes at the wellheads and in various valves in piping used for oil production. these emulsions can increase pumping and transportation costs, facilitate the corrosion of producing and processing equipment, and the poisoning of refinery catalysts [ - ]; [ ]. [ ], mentioned that the emulsifying agent separates the dispersed droplets from the continuous phase. many industrial processes of demulsification have been employed in one application or the other including chemical and electromagnetic processes [ ]; [ ]; [ ]; and [ ]. the first application of microwave irradiation as an emulsion separation technique was by the pioneering works of [ ] and [ ]. since then, there have been a significant number of research interests in this technique [ ]; [ ]; [ ]; [ ]; [ ]; and [ ]. the effects of inorganic salts and inorganic acids in microwave demulsification of water-oil emulsions were investigated by [ ]. according to the authors, the separation efficiency as well as the demulsification rate are enhanced with increasing concentration of inorganic acids and also with the inorganic salt (nacl, kcl, nano , and na so ) concentration in dilute range (< . m). using water-n-decane emulsion, [ ] studied the role of asphaltenes and resins on the stability of emulsion during microwave demulsification process. [ ] depicted that the rate of temperature increase decreases the dielectric properties and volumetric heat generated. [ ] showed that emulsion stability was related to surfactant concentration, stirring time, temperature, the water-to-oil phase ratio and agitation speed. [ ], performed comparative analyses of the demulsification of water-oil emulsion using microwave irradiation energy and conventional thermal heating by comparing the percentage of water separated, and droplets size distribution in each crude oil. the objective of the current research was to investigate the potential of microwave heating technology on the separation of - % and - % water-in-oil (w/o) emulsions. . materials and methods in this manuscript, elba domestic microwave oven model: emo ss, its rated power output is watts and its operation frequency is mhz was modified and converted from batch process system into a continuous process and used as shown in figure . figure : continuous microwave processes microwave control panel feed tank pump data loggers thermocouples pc with picolog r software glass coil tube turntable microwave cavity abdurahman.n.h et.al / energy procedia ( ) – three thermocouples type (k-iec- - ) were connected to pico-tc- data loggers, and then the thermocouples connected to the settling tank. the data logger was connected to pc; with pico log rs. . software. the thermocouples were inserted in the settling tank to different locations top, middle, and bottom of the emulsion sample to measure local temperatures. the rate of water separation in sedimentation depends on the settling velocity of water droplets in the emulsion. according to the force balance and stoke’s law, the settling velocity of water droplets through the oil is given by: o ow w dg v µ ρρ *)( − = ( ) where: wv = settling velocity of water; =wρ density of water; =oρ density of oil; =oµ viscosity of oil; g = gravity acceleration; d= diameter of droplets. from above equation ( ), the viscosity of oil ( oµ ), is very sensitive to temperature. as temperature increases due to microwave radiation, viscosity decreases much faster than density difference )( ow ρρ − . therefore, the heating, either by microwave or by conventional heat, increase the velocity of water, ( wv ), and makes the separation of water-in-oil emulsion faster. . sample preparation and procedures a crude oil sample was collected from malaka refinery, malaysia. at the laboratory, samples of - % and - % water-in-oil emulsions were prepared using crude oil and tap water. agent-in-oil method techniques followed for samples preparation. in this method, the emulsifying agent is dissolved in the oil phase. then water has been added directly to the mixture and agitated vigorously with mixture for minutes. the emulsifying agent used in this study is natural surfactant, ns- - which is ump product. the prepared samples were tested for w/o or o/w emulsions. all samples were w/o type. the glass container, containing ml graduated beaker of emulsion sample was placed in the center of emo ss microwave oven, and microwave radiation was applied at the highest power setting ( watt). the radiation time varied from - minutes irradiation of microwave at mhz. after radiation, samples were taken out quickly from the oven and a calibrated glass thermometer was inserted in the sample in order to read the temperature at different locations. table shows experimental results of microwave heating. table : experimental results of microwave heating radiation time t, sec temperature increase, dtco heating rate dt/dt, c/sec volume rate of heat generation mwq cal/sec-cm water: . . . . . . . . . . . . . . . . . . . . . . . . . . . crude oil: . . . . . . . . . . . . . . . . . . . . . . . . . . . n.h. abdurahman et al. / energy procedia ( ) – abdurahman.n.h et.al / energy procedia ( ) – . introduction a problem in mature oil fields is the sizeable amount of water accompanying the produced crude oil. water is also injected into the crude in course of steam treatment of producing wells or during de-salting operations. petroleum emulsions readily form from water/oil mixtures in turbulent flows or due to pressure gradients in reservoir pores, in the chokes at the wellheads and in various valves in piping used for oil production. these emulsions can increase pumping and transportation costs, facilitate the corrosion of producing and processing equipment, and the poisoning of refinery catalysts [ - ]; [ ]. [ ], mentioned that the emulsifying agent separates the dispersed droplets from the continuous phase. many industrial processes of demulsification have been employed in one application or the other including chemical and electromagnetic processes [ ]; [ ]; [ ]; and [ ]. the first application of microwave irradiation as an emulsion separation technique was by the pioneering works of [ ] and [ ]. since then, there have been a significant number of research interests in this technique [ ]; [ ]; [ ]; [ ]; [ ]; and [ ]. the effects of inorganic salts and inorganic acids in microwave demulsification of water-oil emulsions were investigated by [ ]. according to the authors, the separation efficiency as well as the demulsification rate are enhanced with increasing concentration of inorganic acids and also with the inorganic salt (nacl, kcl, nano , and na so ) concentration in dilute range (< . m). using water-n-decane emulsion, [ ] studied the role of asphaltenes and resins on the stability of emulsion during microwave demulsification process. [ ] depicted that the rate of temperature increase decreases the dielectric properties and volumetric heat generated. [ ] showed that emulsion stability was related to surfactant concentration, stirring time, temperature, the water-to-oil phase ratio and agitation speed. [ ], performed comparative analyses of the demulsification of water-oil emulsion using microwave irradiation energy and conventional thermal heating by comparing the percentage of water separated, and droplets size distribution in each crude oil. the objective of the current research was to investigate the potential of microwave heating technology on the separation of - % and - % water-in-oil (w/o) emulsions. . materials and methods in this manuscript, elba domestic microwave oven model: emo ss, its rated power output is watts and its operation frequency is mhz was modified and converted from batch process system into a continuous process and used as shown in figure . figure : continuous microwave processes microwave control panel feed tank pump data loggers thermocouples pc with picolog r software glass coil tube turntable microwave cavity abdurahman.n.h et.al / energy procedia ( ) – three thermocouples type (k-iec- - ) were connected to pico-tc- data loggers, and then the thermocouples connected to the settling tank. the data logger was connected to pc; with pico log rs. . software. the thermocouples were inserted in the settling tank to different locations top, middle, and bottom of the emulsion sample to measure local temperatures. the rate of water separation in sedimentation depends on the settling velocity of water droplets in the emulsion. according to the force balance and stoke’s law, the settling velocity of water droplets through the oil is given by: o ow w dg v µ ρρ *)( − = ( ) where: wv = settling velocity of water; =wρ density of water; =oρ density of oil; =oµ viscosity of oil; g = gravity acceleration; d= diameter of droplets. from above equation ( ), the viscosity of oil ( oµ ), is very sensitive to temperature. as temperature increases due to microwave radiation, viscosity decreases much faster than density difference )( ow ρρ − . therefore, the heating, either by microwave or by conventional heat, increase the velocity of water, ( wv ), and makes the separation of water-in-oil emulsion faster. . sample preparation and procedures a crude oil sample was collected from malaka refinery, malaysia. at the laboratory, samples of - % and - % water-in-oil emulsions were prepared using crude oil and tap water. agent-in-oil method techniques followed for samples preparation. in this method, the emulsifying agent is dissolved in the oil phase. then water has been added directly to the mixture and agitated vigorously with mixture for minutes. the emulsifying agent used in this study is natural surfactant, ns- - which is ump product. the prepared samples were tested for w/o or o/w emulsions. all samples were w/o type. the glass container, containing ml graduated beaker of emulsion sample was placed in the center of emo ss microwave oven, and microwave radiation was applied at the highest power setting ( watt). the radiation time varied from - minutes irradiation of microwave at mhz. after radiation, samples were taken out quickly from the oven and a calibrated glass thermometer was inserted in the sample in order to read the temperature at different locations. table shows experimental results of microwave heating. table : experimental results of microwave heating radiation time t, sec temperature increase, dtco heating rate dt/dt, c/sec volume rate of heat generation mwq cal/sec-cm water: . . . . . . . . . . . . . . . . . . . . . . . . . . . crude oil: . . . . . . . . . . . . . . . . . . . . . . . . . . . n.h. abdurahman et al. / energy procedia ( ) – abdurahman.n.h et.al / energy procedia ( ) – table depicts experimental results of microwave heating. table : experimental results of microwave heating radiation time t, sec temperature increased dt, co heating rate dt/dt, c/sec volume of heat generation mwq cal/sec-cm - % w/o emulsion . . . . . . . . . . . . . . . . . . . . . . . . . . . - % w/o emulsion . . . . . . . . . . . . . . . . . . . . . . . . . . . . results and discussion the average temperature increasing rates for emulsion ratios of - %, and - % of water-in-oil emulsions were . , and . respectively. it is observed that the rates of heating decreases with temperature increases, this might attributed due to decreasing of dielectric loss of water [ ; ; ], figure shows the phenomena, while figure depicted the volume rates of heat generation versus the radiation time, it is clearly that the volume rates of heat generation increases in early stages of the microwave radiation, then it states decreases at microwave exposure time increases [ ]. . . . . . . . . radiation time [t,sec] h ea tin g ra te [d t/ dt , c /s ec ] water crude oil - % w/o - % w/o figure : heating rates vs. radiation time abdurahman.n.h et.al / energy procedia ( ) – . . . . . . . radiation time, [t sec] v ol um e ra te , q [c al /s ec .c m ] - % w/o crude oil water - % w/o figure : volume rate of heat generation vs. radiation time figures and have shown the separation of water from - % and - % water-in-oil emulsions respectively. all experimental tests have shown that microwave radiation is very effective in separation of water-in-oil emulsions, [ ; ]. results of figures and illustrate that microwave radiation can raise the temperature of emulsion, reduce viscosity and make separation is faster, as suggested by equation ( ). figure : separation of water from - % water-in-oil emulsion figure : separation of water from - % water-in-oil emulsion n.h. abdurahman et al. / energy procedia ( ) – abdurahman.n.h et.al / energy procedia ( ) – table depicts experimental results of microwave heating. table : experimental results of microwave heating radiation time t, sec temperature increased dt, co heating rate dt/dt, c/sec volume of heat generation mwq cal/sec-cm - % w/o emulsion . . . . . . . . . . . . . . . . . . . . . . . . . . . - % w/o emulsion . . . . . . . . . . . . . . . . . . . . . . . . . . . . results and discussion the average temperature increasing rates for emulsion ratios of - %, and - % of water-in-oil emulsions were . , and . respectively. it is observed that the rates of heating decreases with temperature increases, this might attributed due to decreasing of dielectric loss of water [ ; ; ], figure shows the phenomena, while figure depicted the volume rates of heat generation versus the radiation time, it is clearly that the volume rates of heat generation increases in early stages of the microwave radiation, then it states decreases at microwave exposure time increases [ ]. . . . . . . . . radiation time [t,sec] h ea tin g ra te [d t/ dt , c /s ec ] water crude oil - % w/o - % w/o figure : heating rates vs. radiation time abdurahman.n.h et.al / energy procedia ( ) – . . . . . . . radiation time, [t sec] v ol um e ra te , q [c al /s ec .c m ] - % w/o crude oil water - % w/o figure : volume rate of heat generation vs. radiation time figures and have shown the separation of water from - % and - % water-in-oil emulsions respectively. all experimental tests have shown that microwave radiation is very effective in separation of water-in-oil emulsions, [ ; ]. results of figures and illustrate that microwave radiation can raise the temperature of emulsion, reduce viscosity and make separation is faster, as suggested by equation ( ). figure : separation of water from - % water-in-oil emulsion figure : separation of water from - % water-in-oil emulsion n.h. abdurahman et al. / energy procedia ( ) – abdurahman.n.h et.al / energy procedia ( ) – conclusions based on results of this manuscript, it can be concluded that microwave heating technology has been successfully applied for demulsification of - % and - % water-in-oil emulsions. microwave radiation is very effective in separation of water-in-oil emulsions, in this regards the average temperature increasing rates for emulsion ratios of - %, and - % of water-in-oil emulsions were . , and . respectively. the results obtained in this study have exposed the capability of microwave heating technology in demulsification of water –in-crude oil emulsion. further works are nevertheless required to provide deeper understanding of the mechanisms involved to facilitate the development of an optimum system applicable to the industry. references [ ] sjoblom, j., ming yuan, l., hoiland, h and johansen, j.e. water-in-crude oil emulsions from the norwegian continental shelf, part iii. a comparative destabilization of model systems. surfaces. , ( ) - . [ ] sjoblom, j., mingyuan, l., christy, a.a and gu, t. water-in-crude oil emulsions stability. colloids and interfaces. ( ), : - . [ ] sjoblom, j., mingyuan, l., christy, a.a and ronningsen, h.p. water-in-crude oil emulsions from the norwegian continental shelf, . ageing of the interfacially active compounds and the influence of the stability. colloid and surf.a, ( ), : - . [ ] schramm, l. l. petroleum emulsion. in.: schramm, l.l. emulsions fundamentals and applications in the petroleum industry, - . american chemical society, washington dc. . [ ] kenneth j. lissant, "emulsification and de-emulsification, a historical overview", colloids and surfaces, , ( ). [ ] chen, g., he, g. separation of water and oil from water-in-oil emulsion by freeze/thaw method. sep. purif. technol. , ( ) - . [ ] rajakovic, v., skala, d. separation of water-in-oil emulsions by freeze/thaw method and microwave radiation. sep. purif. technol. , ( ) - . [ ] selvarajan r., anantha subramaniam s., and robert a. m. "aqueous dispersion of an oil soluble demulsifier for breaking crude oil emulsions", (us patent no. , , ), ( ). [ ] eow, j. s., ghadiri, m., sharif, a. o., williams, t. j. electrostatic enhancement of coalescence of water droplets in oil: a review of the current understanding. chemical engineering journal ( ), ( ) – . [ ] klaila, w. j. method and apparatus for controlling fluency of high viscosity hydrocarbon fluids. us patent , , , january , . [ ] wolf, n. o. use of microwave radiation in separating emulsion and dispersion of hydrocarbons and water. us patent , , , april , . [ ] fang, c. s., lai, p. m. c. microwave heating and separation of water-in-oil emulsion. j. microw. power electromagn. energy, ( ), ( ) - . [ ] fortuny, m., oliveira, c. b. z., melo, r. l. f. v., nele, m., coutinho, r. c. c., santo, a. f. effect of salinity, temperature, water content, and ph on the microwave demulsification of crude oil emulsion. energy & fuels , ( ) - . [ ] anisa, a.n.i., nour, a.h. “emulsion separation rate enhancement via microwave heating tech”., national conference on postgraduate research (ncon-pgr), ump conference hall, malaysia. . [ ] huda, s.n., nour, a.h. microwave separation of water-in-crude oil emulsions, international journal of chemical and environmental engineering, ,( ), ( ) page - . [ ] abdulbari, h.a., abdurahman, n.h., rosli , y.m., mahmood, w.k., azhari, h.n. demulsification of petroleum emulsions using microwave separation method, international journal of the physical sciences vol. ( ), ( ) - . [ ] nour, a.h., anisa, a.n.i., nour, a.h. demulsification of water-in-oil (w/o) emulsion via microwave irradiation: an optimization, scientific research and essays vol. ( ), ( ) - . [ ] chan, c. c., chen, y. c. demulsification of w/o emulsions by microwave radiation. sep. sci. technol. ( ), ( ) - . [ ] xia, l. x., lu, s. w., cao, g. y., . salt-assisted microwave demulsification. chem. eng. commun. , - . untitled biofeedback �association for applied psychophysiology & biofeedback volume , issue , pp. – www.aapb.org doi: . / - - . . special issuespecial issue managing traumatic brain injury: appropriate assessment and a rationale for using neurofeedback and biofeedback to enhance recovery in postconcussion syndrome michael thompson, md, lynda thompson, phd, cpsych, bcn, andrea reid-chung, ma, ccc, bcn, and james thompson, phd, bcn add centre/biofeedback institute of toronto, mississauga, ontario, canada; evoke neuroscience, inc., new york, ny keywords: concussion, traumatic brain injury (tbi), electroencephalogram (eeg), neurofeedback, heart rate variability (hrv) impairments that may result from a mild traumatic brain injury (tbi) or concussion can be both severe and long- lasting. this article will list some of the common persisting symptoms that may occur and give a brief description of the neuropathological processes that can be triggered by tbi, including diffuse axonal injury and its effects on the mitochondrial kreb’s cycle and the production of adenosine triphosphate, the brain’s source of energy. this is followed by a summary of a comprehensive assessment process that includes quantitative electroencephalography, evoked po- tentials, heart rate variability (hrv) measures, neuropsy- chological testing, and blood and urine analysis. details concerning a neurophysiological approach to effective treatment are given. these include conventional single- channel neurofeedback (nfb), also called brain-computer interface training, low-resolution electromagnetic tomog- raphy z-score neurofeedback, hrv training, and counsel- ing on diet, sleep, and exercise. the authors expand the discussion on their treatment approach to include a neuroanatomical explanation of why the practitioner should consider combining the nfb training with hrv training. introduction this article provides an overview of how postconcussion syndrome is assessed and, for the most part, successfully treated even a number of years after injury. it provides a clinical rather than a research perspective and is based primarily on work carried out at the add centre and biofeedback institute of toronto with clients who have suffered traumatic brain injuries (tbi). success is measured in terms of patients having sufficient amelioration of cognitive and emotional symptoms to be able to resume and succeed in their social, academic, and/or employment pursuits. to date, this has been achieved in all cases in which the person did sufficient training ( or more sessions). eventually, we will follow this descriptive article with a case series detailing outcomes. (see also the initial case study by bhandari, thompson, and reid-chung, , in this issue of biofeedback). here we summarize the most common presenting symptoms and the assessment process, including a rationale for the use of -channel quantitative electroencephalogram (qeeg), evoked potentials (also called event-related potentials [erps]), heart rate variability (hrv) measures, biomedical analysis, and neuropsycho- logical testing. also included is a short description of the treatment approach. interventions may include single- channel neurofeedback, low-resolution electromagnetic tomography (loreta) z-score neurofeedback, hrv training, and metacognitive strategies, plus counseling regarding diet and supplements, sleep hygiene, and exercise. symptoms there is nothing mild about the impairments that may result from a mild tbi, which is commonly called a concussion. a lack of objective pathognomonic signs of concussion means that a physician’s diagnosis often rests, for the most part, on the patient’s report of subjective symptoms, such as headache or ‘‘seeing stars.’’ in % of cases in athletes, concussion does not involve loss of loreta is a widely used statistical technique to analyze surface eeg signals and determine which sites deeper in the cortex are the sources of the surface electrical activity. today’s loreta software produces instantaneous displays of cortical processes, usable for neurofeedback training. loreta z-score training involves training cortical processes toward normalcy, based on a comparison to a normative database. w in te r | b io fe e d b a c k consciousness (mccrory et al., ). common presenting symptoms shortly after a concussion include dizziness, nausea, headaches, balance deficits, and blurred vision. the diagnosis of concussion should be made by a physician in the period immediately following the trauma, preferably within a few hours of the injury. a designated health care professional with appropriate training may make the diagnosis in remote areas where there is no physician available (tator, ). the longer-term problems are referred to as postcon- cussion syndrome when symptoms persist for weeks or months, and this is more common after repeated brain injuries. symptoms include fatigue, sleep disturbance, slowed reaction time, plus cognitive and emotional changes that produce difficulties in everyday life. the cognitive problems include slowed processing speed, poor sustained attention, poor concentration, impaired short-term and long-term memory, and learning problems. language problems, including word-finding difficulties as well as poor comprehension, are also frequently observed among patients with tbi. emotional changes may include depres- sion, anxiety, labile mood, irritability, and anger (‘‘a short fuse’’). unfortunately, in some cases, family and friends notice a major personality change to which the patient may be oblivious because self-perception can also be affected. it is not at all uncommon for someone to present years after the injury with all of these difficulties present to varying degrees. pathology of a tbi a variety of neuropathological processes can be triggered by damage caused when brain matter collides with the rough, ridged inside edges of the skull or the tough falx cerebri, which is an infolding of dura mater between the hemispheres. with rapid deceleration, as in an automobile crash or when a football player is running at full speed and is tackled, there is a coup injury, where the brain first hits the skull, and a contrecoup injury, as it rebounds and hits against the opposite wall of the skull (see figure ). the results of this type of injury are usually assessed in the hospital with the more commonly used imaging techniques. these techniques may include positron emission tomogra- phy (pet), single-photon emission computed tomography (spect), magnetic resonance imaging (mri), and func- tional mri (fmri). a pet scan measures glucose metabolism, and pet images provide a visual display of brain activity by detecting where a radioactive form of glucose goes while the brain performs a given task. spect scans, which track perfusion (blood flow), are significantly less expensive than pet scans, in part because they are able to use longer-lived and more easily obtained radioisotopes than pet. both of these measures are invasive in the sense that radioactive isotopes must be used. mri and fmri have the advantage of not requiring any injection or ingestion of radioactive material, but they involve a noisy environment, and they do require the patient to lie very still in the tube while the magnetic imaging is being done. charles tator, a neurosurgeon and concussion expert in toronto, in a review article states that routine computed tomography and mri scans almost always appear normal in concussion (tator, ). even pet, which indicates tissue metabolic activity by virtue of the regional glucose uptake; spect, which measures blood flow in the brain; and fmri, which measures the blood-oxygen level–dependent response that will vary with oxygen uptake, may fail to detect a common type of injury associated with tbi called diffuse axonal injury (dai; thatcher, ; thatcher, walker, gerson, & geisler, ). diffuse axonal injury dai is a primary pathologic feature of brain injury in concussions at all levels of severity (kushner, ; thompson & hagedorn, ). dai occurs both with hitting the head and also when there is rapid acceleration/ deceleration and/or quick rotation of the brain such as may occur with a whiplash or a blast injury. dai is caused by the twisting and stretching of axons or, in severe head injuries, the tearing or shearing of axons (see figure ). an axon is a nerve connection that goes from the cell body of one neuron to the dendrite or cell body of another neuron. it connects to the next neuron at a chemical junction called a synapse. when a neuron fires, the electrical impulse travels down the axon, at times a long distance, to the end of the axon, where it causes the release of a chemical called a neurotransmitter. this neurotransmitter enters the synap- tic space between the end of the axon and the receptor sites on the dendrite of the neuron that is receiving the ‘‘message.’’ one such neurotransmitter is glutamate, which is important in this discussion and is shown in figure . clearly, damage to an axon will interfere with the transmission of messages from one neuron to another. although the biochemical and structural changes caused by dai may not be detectable by mri, eeg is able to detect the electrophysiological results of the disruption in communication between neurons. the rotational forces affecting the brain that result in dai also set off a metabolic cascade that includes a flood of neurotransmitter release, including glutamate. glutamate excess will stimulate neurons to fire incessantly. this results in an increase in neuronal permeability with an thompson et al. b io fe e d b a c k | w in te r influx of sodium and calcium and a release of potassium. both sodium (naþ) and calcium (ca þ) excess can interfere with mitochondrial function. with normal blood flow and nutrition, the mitochondria can produce energy in the form of adenosine triphosphate (atp) by means of the citric acid cycle (krebs cycle). energy is essential to life, and it is required in the cell membrane for the transport of ions against a concentration or electrical gradient. without this figure . example of sites of injury in traumatic brain injury. drawing by maya berenkey from the companion to the neurofeedback book (in press) using figures by amanda reeves in the neurofeedback book. figure . structure of a neuron drawn by maya berenkey. the terminal button is the presynaptic link to the dendrite of the next neuron. this synaptic transmission is disrupted when there is diffuse axonal injury. (note that this figure shows a pyramidal cell. only pyramidal cells produce the extracellular currents that summate to produce the electroencephalogram.) figure from the companion to the neurofeedback book (in press). using neurofeedback and biofeedback in postconcussion syndrome w in te r | b io fe e d b a c k energy source, the cell cannot depolarize and repolarize normally. cell death is the eventual result. with a shut down of the mitochondrial production of atp, there is a reduction of energy production and a resulting energy crisis because, to keep firing, the neurons demand extra energy. in addition to the direct interference with atp formation in the mitochondria due to the influx of sodium and calcium, there is also an additional problem due to the vasoconstriction caused by the excess release of potassium. potassium constricts the blood vessels and decreases blood flow to the compromised area in the brain. the mitochon- drial krebs cycle requires fuel to keep running. in simple terms, this fuel includes glucose, fats, amino acids for coenzymes, and vitamins for the enzymatic processes. however, the constriction of the blood vessels caused by the excessive release of potassium limits the supply of these necessary nutrients and oxygen to the cell. the high-energy demand, restricted blood flow, and oxygen debt together create the aforementioned energy crisis that exhausts the neurons (see figure ). this will inevitably lead to symptoms such as mental confusion and failed memory, symptoms commonly seen in people who have had a concussion. the brain will take varying amounts of time to recover. the time to restore the chemical balance will vary between people and will depend on many variables including age, general health, and many other factors, such as nutrition. children and females, for example, are more vulnerable to the effects of concussion, as mentioned by tator ( ). long-term potentiation is decreased, and long-term depression is increased. the membrane excit- ability is reduced. the diagram in figure , adapted after a figure from the ucla brain research centre, implies that within about week, one may observe neurochemical recovery. however, time lines predicted by different authors do show a wide range. because of changes and subsequent derangements in cerebral glucose metabolism, persons suffering from even minimal tbi may remain vulnerable to second-impact injury for periods of up to a few months (giza & hovda, ). other authors note that hypermetabolism and an figure . schematic diagram of a synaptic junction. the figure shows, at the top, the presynaptic ending of the axon (called a ‘‘button’’ in figure ) and the postsynaptic receptor sites for glutamate: the a-amino- -hydroxy- -methyl- -isoxazolepropionic acid receptor (ampa), which is a glutamate receptor site, and the n-methyl-d-aspartate (nmda) receptor site, which is initially blocked by magnesium ions. this figure is often used to explain long-term potentiation. it is illustrated here to show the synapse. thanks are extended to wikipedia images; bruno dubuc, website of canadian institutes of health research; institute of neurosciences; mental health and addiction (nmha); and to copyleft; the content of the site the brain from top to bottom is under copyleft. � is also from nature reviews, neuroscience, nature publishing, . thompson et al. b io fe e d b a c k | w in te r energy crisis lead to a secondary reaction with increased regional cerebral blood flow (rcbf; occurs after about minute) to meet increased energy demands needed to restore ionic membrane balances (dewitt et al., ; meyer, kondo, szewczykowski, nomura, & teraura, ; nilsson & nordström, ). shaw ( ) notes that this initial increase in rcbf is followed by a subsequent decrease of up to % in rcbf for to weeks depending on the severity of injury. because of factors that include the gradual death of some neurons after dai and the long-term decrease in cbf that means the energy crisis in cells cannot be resolved, it is possible for symptoms to worsen a few weeks after the concussion so that they are more serious than symptoms seen after initial neurochemical recovery during the first week. this may be a factor contributing to the susceptibility of athletes who have experienced one head injury to experience a second concussion in the period after an initial head injury. the results of subsequent head injuries can be more profound, even when the severity is less, and resolution of symptoms will take longer. second- impact syndrome is a term used when the second injury occurs before there has been recovery from the first tbi, and it is a serious condition that involves cerebral swelling that results in death or major neurological deficits. this is why doctors have to be careful when making return-to-play decisions in athletes. assessment general considerations conventional imaging techniques may miss dai in mild- to-moderate tbi. further, conventional neuropsychological testing and symptom checklists, such as those traditionally used with injured athletes, have been found to normalize within a few days to a few weeks. for this reason, a more advanced paradigm is needed to detect this type of injury. figure . steps contributing to neuronal cell death. national institutes of health (nih) government document in public domain. although originally used by the nih to illustrate changes after a stroke, this diagram applies equally well to the energy crisis that ensues after traumatic brain injury. the next figure summarizes some of the factors that contribute to this energy crisis. using neurofeedback and biofeedback in postconcussion syndrome w in te r | b io fe e d b a c k in a half dozen points, the authors summarize research done with athletes who suffered a mild tbi. this research used comparisons of multiple testing domains and involved development of a new metric for assessing the sequelae of concussion and measurement of recovery (thompson, sebastianelli, & slobounov, ): . sr (self-report) is sensitive within hours. . np (neuropsych) testing typically normalizes within week. . postural testing typically normalizes within to days. . eeg measures, when combined with postural tasks, are sensitive beyond the -day period. . combining modalities is more sensitive and reliable than any single method. . loreta is effective to localize cortical areas affected by the head injury. thompson found that no one test was sufficient, and he recommended the use of a testing paradigm that combines the most sensitive tests from each modality. based on this research, and that of others in this field, a multimodal assessment method for the comprehensive measurement of brain functioning was developed. the primary tool for data collection is the brain injury assessment tool (biat), and this is used along with computerized neuropsychological testing and biochemical analysis (www.evokeneuroscience. com). the biat instrument rapidly, with minutes of data collection, measures -channel eeg, qeeg, erps, and hrv. the assessment employs a simultaneous continuous performance test during which erps are measured and also uses a standardized questionnaire. an additional balance assessment using a force plate is also available and can be integrated into this assessment. biochemical testing of blood and urine can be added as deemed necessary. this is the methodology now used at the add centre/biofeedback institute in toronto. this testing is uniformly revealing abnormalities in our clients, even years after the primary injury. role of qeeg in assessment the principle findings in a qeeg, regardless of the time elapsed since the concussion, can include eeg slowing, decreased power, episodic discharges, and changes in figure . chemical and metabolic changes after traumatic brain injury. adapted from david a. hovda, phd, ucla brain injury research center, and from a drawing in giza and hovda ( ). thompson et al. b io fe e d b a c k | w in te r coherence. a slowed peak frequency, also referred to as the dominant frequency, is a common finding after a tbi (angelakis, lubar, stathopoulou, & kounios, ). normal adult peak frequency, measured in the occipital region with eyes closed, is about hz. after a concussion, it may drop into the low alpha range, perhaps hz, or even fall into the theta range. a dominant frequency less than hz in an adult is considered abnormal. another common finding is reduced overall power. the most consistent power findings after a concussion are reduced power in the higher-frequency bands ( – hz) and increased slow waves ( – hz; slobounov, sebastianelli, & simon, ; thatcher, ). there are long-term changes in the - to -hz/ - to -hz ratio (korn, golan, melamed, pascual- marqui, & friedman, ; slobounov, cao, & sebastia- nelli, ). a change (increase) in this - to -hz/ - to - hz ratio activity is negatively correlated with patient outcome months after injury (leon-carrion, martin- rodriguez, damas-lopez, barroso y martin, & domi- nguez-morales, ). thatcher has suggested that power changes in the eeg following concussion result from dysfunctional ionic channels of neuronal membranes (e.g., naþ, kþ, caþþ) and reduced average current flux (thatcher et al., ). decreased and/or increased coherence is a common finding. coherence reflects communication be- tween different sites in the brain and represents the amount of phase-locked activity in a particular frequency band. tbi will disrupt coherence. the most common finding is a decrease in coherence that is colloquially called a ‘‘discon- nect.’’ a less frequent but important finding may be episodic discharges. a dramatic example reported by m. barry sterman (personal communication, march ) was that one of his patients dropped his -month-old infant and was accused of abuse. sterman determined that the probable cause of the accident in this very conscientious parent was a sudden episodic discharge with momentary loss of muscle tone and consciousness. addition of erps to assessment measures information from evoked potentials, also called event- related potentials (erps) because they are time locked to a specific event (sight or sound or even touch), can be used following concussion to determine the intactness of cortical pathways and speed of processing within these pathways (de beaument et al., ; dupuis, johnston, lavoie, lepore, & lassonde, ). erps reflect the neural activities associated with cognitive/behavioral demands and thus provide access to an improved understanding of brain functioning that goes beyond either neuropsychological testing or motor testing (gosselin et al., ). erps have been shown to be resistant to practice effects and are therefore a hearty diagnostic assessment tool (mendez, hurley, lassonde, zhang, & taber, ) that can be repeated as often as necessary. the population of people who have suffered a tbi demonstrate reduced amplitudes for the p components (p a and p b) of their erps. (for a detailed explication of p a, p b, and other erp components, see polich, ). when describing erps, ‘‘p’’ refers to positive-going waves and ‘‘n’’ to negative-going waves. the number, such as (sometimes shortened to just ), refers to the number of milliseconds after the stimulus when you expect the response to occur. this reduced amplitude can indicate diminished attention because the amplitude of the p has been shown to be related to the amount of attention allocated to information processing (bernstein, ; duncan, kosmidis, & mirsky, ). in addition to lower amplitude, the latency of the p response has been found to be greater, and this delay in conscious processing of information is called a slowed p . this increased latency in the p response correlates with slowed cognitive processing (lavoie, dupuis, johnston, leclerc, & lassonde, ). earlier erp responses are observed at less than milliseconds, which is before there is conscious awareness of the stimulus. they reflect early brain sensory processing. in our experience, patients with tbi generally have sensory components (p and n ) that are longer latency and lower amplitude compared with non-tbi patients. p also tends to be longer latency and of lower amplitude (see figure ). p a is an attention-orienting frontal component, whereas p b reflects sustained attention and is more central-parietal, with the largest amplitude being observed at pz. these observations of longer latencies with the p erps may help us understand why there are persistent problems with attention and concentration after concussion. addition of hrv to assessment measures the observation that tbi impairs cardiac function has become increasingly apparent through work done with relatively young athletes and with clients who have had vehicular accidents (car, motorcycle, bicycle). figure contrasts hrv in a healthy adult with that of an athlete who has suffered a concussion. it demonstrates that, after a concussion, even a healthy athlete can show significant hrv changes. the top electrocardiogram shows a -second sample, and below it is a tracing of variations in heart rate over a -second time period, both from the same healthy -year-old male. these demonstrate what one would expect in a healthy person: heart rate variations are even with high amplitude and steady rhythmicity. the using neurofeedback and biofeedback in postconcussion syndrome w in te r | b io fe e d b a c k figure . pre (black) and post (gray) p event-related potential (erp) recordings from the same subject comparing a baseline measurement and a postinjury measure. latency of the p wave is delayed in the postconcussion test, and amplitude of the p wave is reduced following injury. (‘‘big circle’’ refers to the target stimulus in this erp test that is in the program from evoke neuroscience.) figure from thompson & hagedorn in the companion to the neurofeedback book (in press). figure . heart rate variability profile from a healthy adult and from a concussed athlete. from thompson and hagedorn ( ). thompson et al. b io fe e d b a c k | w in te r figure below it shows data from a highly trained male athlete weeks postconcussion. it demonstrates low amplitude and poor rhythmicity of heart rate variations. the amplitude of the variations in heart rate and the standard deviations of the heart rate variations after artifacts have been removed (sdnn) were also both lower than would be expected in a young athlete. these data provide an illustration of how brain injury affects not just the brain but also the heart, specifically that concussion has a negative effect on hrv. similar observations are found postconcussion in clients at the add centre and also have been published by researchers. one example is a study by baguley, heriseanu, felmingham, and cameron ( ). they compared hrv data on tbi age-matched subjects with and without dysautonomia with that of noninjured controls. the mean sdnn (milliseconds) for the control group was . with a standard deviation (sd) of . , whereas the mean sdnn (milliseconds) for the tbi group was . with an sd of . . the total power (ms /hz) of the controls was (sd ¼ , ) and in the tbi group only (sd ¼ , ). the lf power (ms /hz) of the control group was , (sd¼ , ) and in the tbi group only (sd ¼ ). they demonstrated that the tbi group revealed significant differences in hrv parameters compared with controls. neuropsychological testing in a clinical as contrasted to a research setting, testing must be confined to that which can be useful to assist in diagnosis and, more importantly, to design an appropriate treatment program and track the patient’s progress during rehabili- tation. the weschler intelligence scale may be used to obtain a profile of intellectual strengths and deficits with other testing carried out as appropriate for a particular patient. problems with memory and concentration are among the common cognitive sequelae of tbi. in adoles- cents and adults with a tbi presentation, a computerized neuropsychological test battery is used at the add centre. in the interest of brevity, an example from the first page of the report is given in figure . completion of this test battery takes the patient approximately minutes to hour, and the full report is delivered by computer within hour after the testing is competed. the objective testing of aspects of response time and memory involves tests that can be quite difficult, and results, for the most part, do pinpoint the difficulties the patient is experiencing. this computer- ized methodology is simple to administer and can be repeated so the results can be used, in a clinical setting, to follow progress during treatment. the objective test procedures in this computerized neuropsychological test are complemented by subjective self-report questionnaires and validated neuropsychological behavioral and cognitive testing tasks. questionnaires include an alertness rating scale, the zung anxiety and depression self-report scales, an adult adhd self-report scale, a neuropsych ques- tionnaire short form (a series of questions about the patient’s clinical state including mood, attention, sleep, fatigue, aggressiveness, and so on), and a -item medical outcomes survey. this computerized neuropsychological test battery is a cost-effective way to obtain objective and subjective information about the patient and track changes during training. it may be a particularly useful tool for clinicians who do biofeedback but who are not trained in the administration of psychological tests. it is also very helpful in the assessment of patients who could not afford individual testing done by a psychologist. vestibular/balance assessment at the add centre, we are considering adding an assessment tool that uses a force plate to quantify a person’s balance, coordination, and vestibular system following a brain injury. this can be a very sensitive tool that, especially when combined with simultaneous eeg measurements, will pick up functional deficits well after the time that conventional instruments, such as self-report questionnaires and psychometric tesing, have returned to the normal range. the subject has his or her balance tested in various modes (both feet, one foot, eyes open and closed) while standing on a small rectangular force board that sends signals to the computer that evaluates subtle movements. a neurophysiological approach to effective treatment in the acute phase, rest from both physical and cognitive activities is the only treatment that is agreed upon for concussion (mccrory et al., ). basic rehabilitation procedures, as are carried out in hospital settings and in rehabilitation centers, should be adhered to as well. these interventions are necessary but often not sufficient for full cognitive recovery. for later stages of treatment, both neurofeedback/biofeedback practitioners and nutritionists have important complementary techniques to apply. these are now being demonstrated to achieve further results that may be significant and, indeed, often life changing. normalizing the eeg deviations is a first step. this intervention must be designed while keeping in mind that not all deviations from a normative database will corre- spond to symptoms. indeed, we have seen examples of genius correlating with significant deviations from a normal using neurofeedback and biofeedback in postconcussion syndrome w in te r | b io fe e d b a c k figure . the add centre logs in to cns vital signs (www.cnsvs.com) to run a computerized neuropsychological test report (administered through evoke neuroscience). this -year-old client presented months after experiencing a brief loss of consciousness in a fall. this very bright and capable individual has a doctoral degree, yet she was plagued by memory problems and even forgot appointment times, despite e-mail reminders the day before. given past academic and work history, one would expect consistently above-average scores, but testing corroborated self-report of memory problems continuing more than year after the head injury. thompson et al. b io fe e d b a c k | w in te r database. the person with deviations in the auditory cortex who has perfect pitch, for example, does not have the goal of normalizing that aspect of his auditory processing. thus, the cautious practitioner will include only brodmann areas with z-score deviations that correlate with a particular patient’s symptoms of concern and will carefully assess during each session whether the patient’s changes, when meeting the feedback criteria, correlate with symptom relief. normalization should not induce any decrement in cognitive functioning. training that addresses shifting brain functioning toward what is expected for the person’s age is often done using loreta z-score neurofeedback (lnfb). nevertheless, we must note that we have had excellent results using single-channel neurofeedback train- ing with clients who had suffered a tbi in past years. in some cases, we are doing one session of lnfb and one of regular, single-channel neurofeedback each week. lnfb is a logical choice of intervention when working with patients who have had concussions and show multiple deviations involving areas deep in the cortex. single-channel training can affect these due to network properties in the brain’s cortical-subcortical loops, but the loreta training is hypothesized to have a more direct influence on these structures. the initial assessment in the majority of patients who have suffered a tbi typically shows both positive and negative deviations in amplitude (. sd) at multiple sites, often in central midline areas, accompanied by both coherence and phase differences as compared with database norms. lnfb allows the practitioner to address up to parameters, correcting the activity at various sites at the same time for amplitude and/or coherence and/or phase according to the neuroguide database. an example of a summary graph of loreta neurofeedback training is shown in figure . the graph of the learning curve across sessions of loreta neurofeedback training in figure shows a sudden increase at session . this was because the client had to leave the country for several months after six sessions of training. when he came back to canada, some of his symptoms had returned, so he came back to complete his training and achieved good results. neurofeedback training is nearly always combined with hrv training and with monitoring of diet, sleep, and exercise. exercise needs to be appropriate and not jarring to the spine and brain. in the immediate postinjury period, even before nutritional assessment is carried out, an increase in supplementation of omega- essential fatty acids (i.e., fish oil) to several grams per day is usually appropriate. figure . neuroguide program diagram of progress across loreta z-score neurofeedback training sessions. at sessions, this client’s z-scores had moved from . – standard deviations (sd) to , sd at all the brodmann area sites that were chosen to be trained. the cursor has been placed on the highest sd site for the th session and the message that pops up is shown in the figure. this message indicates that this site represents the sd of amplitude (ap) for brodmann area (the insula) on the right side (r) for beta ( – hz in this program). the right insula will have major effects on heart rate variability. it is also involved in affect and executive networks. figure from the companion to the neurofeedback book (in press). using neurofeedback and biofeedback in postconcussion syndrome w in te r | b io fe e d b a c k at the add centre, hrv training is carried out simultaneously with the neurofeedback. as reported in the literature (thompson & hagdorn, ) and in our clinical experience, even healthy athletes can show major cardiac changes postconcussion. instead of heart rate variations that are even, with high amplitude, and steady rhythmicity, the picture becomes one of low amplitude and poor rhythmicity, as illustrated earlier in figure . the standard deviation of rr intervals with artifacts removed (sdnn) has been observed to be unexpectedly low (usually , milliseconds) in concussed athletes before hrv training is done. in one controlled study concerning hrv after a tbi, the tbi group revealed significant differences in hrv parameters compared with controls (baguley et al., ). at the add centre, it is frequently observed that the insulae (right insular cortex as well as left insular cortex) show values that are outside the database norms when analyzed using qeeg and loreta. the insulae are important regulators of autonomic balance, with the right insula affecting the sympathetic and the left the parasym- pathetic nervous system, in part through connections to the nucleus accumbens, which has a role in balancing the sympathetic and parasympathetic systems (nagai, hoshide, & kario, ). there are reciprocal connections between the insula and the anterior cingulate gyrus, amygdala, entorhinal cortex, medialfrontal and orbitofrontal cortex, and the hippocampus. there are reciprocal connections with subcortical autonomic structures, including the lateral hypothalamic area, nucleus tractus solitarius, and the parabrachial nucleus. these areas are also reciprocally connected to each other. the medial prefrontal cortex (mpfc) normally gives a tonic inhibition of the amygdala (thayer, åhs, fredrikson, sollers, & wager, ). dysfunction of the ventral mpfc that results in hypo- figure . figure by maya berenkey after drawings by amanda reeves from the companion to the neurofeedback book (in press). midsagittal representation of selected central midline cortical and subcortical structures (plus the insula, which in reality is not midline but more lateral). thompson et al. b io fe e d b a c k | w in te r activation can result in amygdala excitation of the sympathetic system and results in changes in hrv. figures and illustrate, in a summary format, influences of cortical and subcortical areas that can affect both the patient’s responses to stress and to neurofeedback combined with hrv training. with hrv training, the feedback from the baroreceptors goes directly to the nucleus tractus solitarius. we postulate that it is quite probable that, through these connections, hrv training may directly affect all of the aforementioned cortical and subcortical structures and thus have some influence on affect, stress, and executive networks in the brain. in a clinical setting, it is our responsibility to do all the interventions that may reasonably be expected to help our patients. we therefore combine the hrv training with neurofeedback. for a single-channel feedback session, one sample screen is shown in figure . figure shows conventional single-channel neurofeed- back at fcz combined with hrv training. this screen is often used as an example in teaching because it is a client favorite. it induces a sense of competition between the boats with the client attempting to have a green boat win. to do this they must focus, eliminate all unnecessary thoughts and ruminations, relax, and concentrate. in addition, clients are asked to maintain synchrony between the variations in heart rate (red line) and their breathing (inspiration and expiration shown by the blue line). their sdnn and hrv amplitudes can be immediately calculated for them at the end of the session using the cardiopro program from thought technology. when loreta neurofeedback is being done, the client may do the hrv training as the - channel cap is being put on. clients can also do it during the session by using a second computer with the biofeedback sensors attached to another instrument such as the infiniti from thought technology, as is being used in the foregoing example. from a subjective point of view, our patients have been unanimous in their opinion that one of the most important aspects of their training program has been hrv training followed by using their effortless diaphragmatic breathing when under stress in their everyday life. at the add centre, we also address nutrition. given that nutrition is a complex area requiring an extensive background in biochemistry and physiology, how can the neurofeedback practitioner be of practical assistance to the patient? the simplest route is to have the blood and urine work ordered by their family practitioner and the results forwarded to a nutrition specialist. at the biofeedback institute, we usually do one of the following. figure . schematic representation of structures to highlight the synergistic influences of neurofeedback and biofeedback–heart rate variability. the international – system defines scalp sites for eeg placements, in a grid organized around two axes. fcz is a midline location half way between cz (the center or vertex of the scalp) and fz (the next more frontal midline location). using neurofeedback and biofeedback in postconcussion syndrome w in te r | b io fe e d b a c k . for regular clients (for example, with attention-deficit/ hyperactivity disorder), we recommend ohip (provin- cial health insurance)–covered blood and urine work as recommended by a phd nutritionist/dietitian. this is ordered by the family practitioner, and the results are forwarded to the nutrition specialist. . for complex clients (depression, posttraumatic stress disorder, tbi), we recommend the triad profile from metametrix in the united states, which is then interpreted for us by licensed specialists at evokeneur- oscience. this analysis can go in progressively more advanced stages. it will look at markers for all the relevant nutrients plus toxins and will identify all major imbalances. there is a cost involved for the patient. conclusion in our experiene, postconcussion symptoms may be sufficiently severe and long-lasting as to completely disrupt the academic pursuits or employment of the affected individual. this puts considerable strain on the patient’s social and family life. the emotional and personality changes after a minor traumatic head injury, especially if it is not the first such injury, can be very severe. at the tragic end of the continuum are deaths from accidental overdose, second-impact syndrome in athletes, accidents, or even suicide. traditional assessment procedures do not fully detect the problems, especially not dai. traditional rehabilitation can be helpful but may not fully ameliorate the patient’s cognitive and emotional difficulties. currently, we are able to report that all postconcussion patients who completed a neurofeedback plus biofeedback program at the add centre have been able to return to work and have been successful in the amelioration of most cognition and affect symptoms. clients have included an author who could barely compose a paragraph when first seen years postinjury who subsequently authored three books, a student who had to take a greatly reduced course load all through his undergraduate years after suffering a head injury in first year of university who completed a demanding graduate program in actuarial science with absolutely no accommodations while concurrently doing neurofeedback, and a phd candidate who had been stalled in his thesis work and unable to teach for years after a whiplash injury who returned to his studies and subse- quently completed his doctoral work on artificial intelli- figure . screen from thought technology instruments and programs using the thompson suite, setting up for clinical success (www.bfe.org) for simultaneous neurofeedback and biofeedback training. thompson et al. b io fe e d b a c k | w in te r gence, sending us a copy of his graduation certificate along with a note crediting his recovery to the neurofeedback intervention. these are three examples of what is meant when we say that training can be life changing. a case study of another long-term patient, who had been in a coma and was deemed by insurance to have suffered a catastrophic injury, is described in an accompanying article. the combination of neurofeedback with hrv training and nutritional interventions offers hope for better outcomes because it can result in significant improvements for patients who have suffered a tbi. as was stated at the outset, there is nothing ‘‘mild’’ about the impairments that result from a mild tbi, and individuals who suffer these injuries deserve the opportunity to receive modern treatment methodologies that have the potential to ensure positive outcomes. acknowledgments thanks are extended to tanushree bhandari for assisting with references and maya berenkey for illustrations. competing interests james thompson is the chief science officer at evoke neuroscience inc. michael 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( ). handbook of quantitative electroenceph- alography and eeg biofeedback. st. petersburg, fl: author. thatcher, r. w., biver, c., gomez, j. f., north, d., curtin, r., walker, r. a., & salazar, a. ( ). estimation of the eeg power spectrum using mri t relaxation time in traumatic brain injury. clinical neurophysiology, , – . thatcher, r. w., walker, r. a., gerson, i., & geisler, f. h. ( ). eeg discriminant analyses of mild head trauma. electroen- cephalography and clinical neurophysiology, , – . thayer, j. f., åhs, f., fredrikson, m., sollers, j. j., iii, & wager, t. d. ( ). a meta-analysis of heart rate variability and neuroimaging studies: implications for heart rate variability as a marker of stress and health. neuroscience & biobehavioral reviews, , – . thompson, j., & hagedorn, d. ( ). multimodal analysis: new approaches to the concussion conundrum. journal of clinical sport psychology, , – . thompson, j., sebastianelli, w., & slobounov, s. ( ). eeg and postural correlates of mild traumatic brain injury in athletes. neuroscience letters, , – . michael thompson lynda thompson andrea reid-chung james thompson correspondence: lynda thompson, phd, cpsych, bcn, add centre, village centre place, mississauga, ontario, canada, l z v , e-mail: landmthompson@gmail.com. thompson et al. b io fe e d b a c k | w in te r causal link between employment and renewable energy consumption: evidence from nigeria mukhtar wakil lawan*, matthew oladapo gidigbi school of management and information technology, modibbo adama university of technology, yola, nigeria abstract: the paper examined the causal link between employment and renew- able energy consumption in nigeria for the period of to using annual time series data. the toda-yamamoto granger causal- ity approach was used for causal analysis and johansen cointegration technique to verify the long-run relationship between model variables. the results supported the conservation hypothesis with unidirectional causality from employment to energy consumption, but no evidence of cointegration was established. the study recommends that nigeria should review its energy policy in order to promote private investment in renewable energy projects towards finding a sustainable solution to help solve the energy crisis, create employment opportunities, and minimise environmental pollution peculiar to long-term use of fossil fuel. keywords: renewable, causality, employment, cointegration, energy policy. ejae , ( ): - issn - udk: . : . ( )" / " . . . : . doi: . /ejae - original paper/originalni naučni rad article info: received: november , correction: february , accepted: march , *e-mail: mukhtar.lawan@mautech.edu.ng introduction for more than a decade, the nigerian government has been pushing for the adaptation of renewable energy into its energy generation mix in response to the persistent energy crisis in the power sector. the existing energy policy under the multi-year tariff order (myto) for the power sector and existing energy laws in the petroleum industry has failed to attract the desired level of investment. the existing gas-fired power plants are largely energy inefficient, and face recurrent gas supply shortages from gas supply hubs situated in the gas-rich niger delta region of the country. rising concerns and debates on the importance of environmental conservation and the reduction of air pollution, particularly from gas flaring, have also provided a strong basis for the government to propel investment in renewable energy. the government strongly believes that this strategy will also provide employment opportunities, while helping to address rising environmental concerns associated with global warming. numerous earlier country-specific studies for nigeria analysed the causality pattern between eco- nomic growth and aggregate energy/electricity consumption, and some used the traditional granger causality approach. therefore, this paper will contribute to the existing literature by analysing causal linkages between renewable energy consumption and employment by using the toda-yamamoto ( ) augmented var approach due to its statistical advantages over the order of integration and cointegration properties of time series. literature review renewable energy sources, like solar, wind, and water, are distinct from fossil fuels due to the absence of the carbon dioxide (co ) gas notably identified by a number of studies (nisbet & myers, ; schell- ing, ; warrick & farmer, ) as one of the green gases that contribute to global warming. ariouri et al. ( ) have identified six economic effects that help in the understanding of the dynamic links between energy consumption and employment. the links consisted of price, substitution, democratic, structural, income, and technological effects. according to papapetrou ( ), the price effect relates to the impact of external shocks on the prices of energy sources, like oil, gas, and coal, which can stimulate economic growth in certain economies and improve employment levels. notable examples here are most of the opec member countries, which rely extensively on the export of energy resources for gov- ernment revenue. the substitution effect explains how shortages or constraint in energy supply may be substituted by labour in certain macroeconomic production scenarios and vice versa. the demographic effect explains the impact of a population boom on the short-run domestic demand for energy from households, and long-run aggregate demand for energy due to changes in the level of the work-force within an economy. the structural effect describes an impact in the form of less energy consumption due to transition from manufacturing to a service-driven economy with minimal impact on unemploy- ment. however, jespersen ( ) argues that this might not be attainable in economies that have an energy-intensive private service sector. the income effect relates to the simultaneous growth of employ- ment and energy consumption, which may be at different rates usually preceded by rapid economic expansion. the more income households get through employment, the higher the demand for goods, services, and subsequently energy. in terms of technological effect, Çetin and eğrican ( ) suggest that changes from traditional energy technology to modern energy technology, such as solar energy, can create direct and indirect employment opportunities depending on a nation’s development level. several empirical studies have tested the direction of causality between energy consumption and economic growth/employment since its introduction in granger ( ). these studies established sup- port for at least one of four hypotheses; conservative, growth, feedback, and neutrality hypothesis. bilgili and ozturk ( ) in a study of g countries over - applied panel cointegration, conventional, and dynamic ols to establish the positive effects of biomass energy consumption on economic growth. ocal and aslan ( ) applied the ardl and toda-yamamoto causality approach using time series covering - for turkey and found evidence of causal flow from economic growth to renewable energy consumption. kahia, aïssa and lanouar ( ) analysed panel data covering the period - for mena net oil importing countries using the panel vector error correction model (pvecm). the study found evidence of simultaneous causality between economic growth and both renewable and non-renewable energy use. payne ( ) employed the toda-yamamoto causality test for u.s. data for the period - and found no evidence of a causal link between renewable, non-renewable energy consumption, and real gdp. however, the empirical results of causal studies have mostly been mixed with no dominant prevailing theory both for the case of developed and developing countries. awokuse ( ) and bahmani-oskooee and alse ( ) have suggested that variation in causal pattern is influenced by several factors including theoretical framework, model variables, foreign policy, country specific characteristics, time period, data frequency, and methodology adopted for the causality model. ejae  ( )  - lawan, m. w., gidigbi , m. o.  causal link between employment and renewable energy consumption: evidence from nigeria the conservative, growth, feedback, and neutrality hypothesis are typically used to analyse the direction of causality between energy consumption and economic growth/employment. the growth hypothesis represents unidirectional causality from energy consumption to economic growth/employ- ment. it suggests that increases in energy consumption lead to higher economic growth/employment level. a number of studies (altinay & karagol, ; ighodaro, ; inglesi-lotz, ; ozturk & bil- gili, ) found evidence in support of the growth hypothesis. the conservative hypothesis indicates a one-way link from economic growth/employment to energy consumption. it implies that higher economic growth/employment will lead to more energy consumption. the empirical findings of some studies (lise, ; matthew et al., ; menyah & wolde-rufael, ; ocal & aslan, ; sadorsky, ) supported the conservative hypothesis. the feedback hypothesis indicates a bidirectional causal link between economic growth/employment and energy consumption. numerous studies (apergis & payne, ; chang et al., ; ebohon, ; kahia et al., ; koçak & sarkgünes, ; lin & moubarak, ; osigwe & arawomo, ; sebri & ben-salha, ) established support for the feedback hypothesis. the neutrality hypothesis indicates the absence of causality in either direction between economic growth/employment and energy consumption. some past empirical studies (akpan & akpan, ; esso, ; menegaki & tugcu, , ; payne, ; vaona, ) provided sup- port for the neutrality hypothesis for the countries under study. the use of granger’s ( ) or sim’s ( ) granger causality approach in the early set of studies were particularly criticised due to use of non-stationary and sometimes cointegrated series. in such instances, the wald test statistic under the null does not follow its usual asymptotic chi-square dis- tribution. hence, other techniques, such as the ardl bounds testing, johansen and juselius ( ) cointegration technique, restricted var with imposed cointegration restrictions, instrumental regres- sion, potential outcome framework, and the surplus-lag approach introduced by toda and yamamoto ( ) along with similar alternatives by dolado and lütkepohl ( ) and bauer and maynard ( ), were applied in later studies. the addition of surplus-lag in the causality model is meant to ensure the wald test statistic follows its usual chi-square asymptotic null distribution in a non-stationary process. the approach also helps to minimise the pre-test bias from unit root and cointegration test at the cost of a decrease in model efficiency. nonetheless, clarke and mirsa ( ) argued that the loss of power in the surplus-lag approach is less when compared to alternatives like vecm due to cointegration restrictions. the latter approach could lead to severe over-rejecting of the null hypothesis of granger non-causality from preliminary test of cointegration. this paper focuses on analysing causal pattern, and employs the toda-yamamoto ( ) surplus-lag approach in the causality model. methodology the study used annual time series data for the period to obtained from the world de- velopment indicators (wdi) of the world bank for the model variables of employment (emp) and renewable energy consumption (rec). the emp variable expressed in percentage measures the pro- portion of people aged and above that are employed in nigeria, while the rec variable measures renewable energy consumption as a percentage of total final energy consumption. order of integration and optimal lag selection the preliminary step for the toda-yamamoto (t-y) granger causality approach is to establish the maximum order of integration (dmax) for model variables and the appropriate lag length (k) for the var system. hence, the order of integration for this study was established using the augmented data set available at http://dx.doi.org/ . / pp yf yf. ejae  ( )  - lawan, m. w., gidigbi , m. o.  causal link between employment and renewable energy consumption: evidence from nigeria dicky-fuller (adf) test, while the appropriate lag length (k) for the var system was determined using four lag selection criteria. this consisted of the akaike information criterion (aic), schwarz informa- tion criterion (sc), hannan-quinn information criterion (hq), and the final prediction error (fpe). model diagnostic in order to ensure the var model is well specified, the serial correlation lm test is used to ensure the residuals are serially independent, and model dynamic stability is verified by analysing the inverse roots of the associated characteristic equation. cointegration test although the cointegration test does not affect the end result of the toda-yamamoto granger causality approach, the study will use the johansen and juselius ( ) maximum likelihood cointe- gration technique. this helps to provide information on the potential long-run association between model variables, and serves as a useful check for our causality model, since cointegrated variables will be expected to exhibit at least a unidirectional causal pattern. the johansen method relies on testing the likelihood ratio of the trace test (λtrace) and max eigenvalue test (λmax) to determine the number of cointegrating vectors for the var equation ( ). - - -Δz = μ + z + Пz +Г ε p t i i t i t p t=Σ ∆ where zt is (n x ) vector of i( ) variables, µ is (n x ) vector of constants, Γ and Π are (n x n) matrix of coefficients and parameters, ∆ is difference operator, and εt is (n x ) vector of error terms. ln ( ) n trace i r itλ = += − Σ − where t stands for the number of observations usable, ln is natural log, and  is characteristic root estimated (eigenvalue). the trace test in equation ( ) test the null hypothesis that the rank of Π is less than or equal to r cointegrating vector(s). max ln ( )itλ = − − the max eigenvalue test in equation ( ) test the null hypothesis for the presence of exactly r coin- tegrating vectors in zt in the var equation ( ). granger causality model the granger causality model is based on the toda-yamamoto ( ) approach. the causal test follows a standard asymptotic distribution for the wald statistic regardless of the order of integration and cointegration between model variables (bosupeng, ). the granger non-causality model is expressed in equation ( ) and ( ). ( ) ( ) ( ) ejae  ( )  - lawan, m. w., gidigbi , m. o.  causal link between employment and renewable energy consumption: evidence from nigeria μ k dmax k dmax t i i t i i t temp emp recδ λ + + = − = −= + Σ Ψ + Σ + μ k dmax k dmax t i i t i i t trec rec empδ λ + + = − = −= + Σ Ψ + Σ + in equations ( - ), δ , ψ and λ are model parameters and k is the appropriate lag length while dmax is maximum integration order. the symbol µt is model uncorrelated error term while emp and rec stand for variables of employment and renewable energy consumption respectively. empirical results and discussion unit root test and optimal lag selection results the results of the unit root test for determining the order of integration for variables of employment (emp) and renewable energy consumption (rec) based on the adf test is shown in table . variables level % critical value first difference % critical value remark emp - . - . - . * - . i ( ) rec - . - . - . * - . i ( ) note: * denotes null rejection of non-stationarity at % level table . augmented dickey-fuller (adf) unit root test results the results in table suggest that the variables of renewable energy consumption (rec) and employ- ment (emp) are both stationary after first differencing and thus, maximum order of integration (dmax) is . this also fulfils the condition to check for the presence of cointegration between the two variables. lag fpe aic sc hq . . . . . * . * . * . * . . . . . . . . . . . . . . . . note: * indicates lag order selected by each criterion table . var lag order selection results the appropriate lag length (k) for the var causality model based on the four information criteria is lag as shown in table results. the model is also found to be dynamically stable and the residuals serially independent. hence, the optimal lag for the granger causality model, var (k + dmax) is . ( ) ( ) ejae  ( )  - lawan, m. w., gidigbi , m. o.  causal link between employment and renewable energy consumption: evidence from nigeria model diagnostic test results the result of the serial correlation lm test is shown in table and the inverse roots of the charac- teristic equation is shown in figure . lag lre* stat prob. rao f-stat prob. . . . . . . . . . . . . . . . . . . . . . . . . note: * edgeworth expansion likelihood ratio statistic table . var residual serial correlation lm test the results in table indicates that serial correlation is removed from the model at % level. figure . inverse roots of ar characteristic polynomial the results in figure established that the var model is dynamically stable as all points lie within the unit circle. cointegration test results the results of the johansen cointegration test for the two i( ) model variables are shown in table . ejae  ( )  - lawan, m. w., gidigbi , m. o.  causal link between employment and renewable energy consumption: evidence from nigeria vector trace statistics critical value probability max-eigen statistics critical value probability ho h λtrace % p λmax % p r = r > . . . . . . r <= r > . . . . . . note: r indicates number of cointegrating vector (s) table . johansen cointegration test results the trace and max-eigen statistics in table indicate the absence of cointegration between the two variables of rec and emp. the null hypothesis of no cointegration cannot be rejected at the % sig- nificance level. the absence of cointegration over the study period lend credence to the energy policy in nigeria that has promoted investment in the petroleum sector to sustain the economy through revenue generation and employment. as a result, most studies (akpan & akpan, ; ighodaro, ; matthew et al., ) for nigeria that used electricity as proxy for energy consumption found evidence of long- run relationship with economic growth. a further emphasis on the dominant use of non-renewables (particularly natural gas) in power generating plants for several decades across the country. granger causality test results the results of the granger non-causality model using the set of equations ( - ) in the augmented level var (k + dmax) for the wald test is shown in table . emp rec emp _ . * ( . ) rec . ( . ) _ note: * denotes null rejection of granger non-causality at % level probability reported in parenthesis table . t-y granger non-causality test results the results in table indicate a one-way causality from employment (emp) to renewable energy consumption (rec) as the null hypothesis of granger non-causality is rejected at % level. it implies that renewable energy consumption will continue to rise so long as employment levels continue to grow in nigeria. hence, execution of renewable energy projects towards power generation will help to create both direct and indirect employment which should induce an income effect, technological effect and lead to higher energy consumption in the nigerian economy. direct jobs can be created in the short-term during construction due to building, procurement, and installation of equipment at renewable based power stations. likewise, additional jobs are created during the course of operation and maintenance of power stations in the long-term. indirect jobs can be created during the course of transmission and distribution of electrical power. these employment opportunities will increase the potential for household spending on goods and services, which will have to be compensated by higher energy consumption, especially by firms, in order to meet those demands. the causal pattern observed in this paper differs from the findings of other studies (akpan & akpan, ; ebohon, ; esso, ; ighodaro, ; osigwe & arawomo, ) for nigeria largely due to ejae  ( )  - lawan, m. w., gidigbi , m. o.  causal link between employment and renewable energy consumption: evidence from nigeria variation in methodological approach. the unrestricted test adopted in this paper minimise the pre- filtering bias likely to affect some of those papers. however, this study is limited by the availability of data on renewable energy consumption, thereby limiting the time period for the causal analysis which could also account for variation in outcomes across these set of related studies. conclusion and policy recommendation the study used annual time series data for the period – to analyse the causal pattern between employment and renewable energy consumption in nigeria. the toda-yamamoto granger non-causality technique was employed for the causality model, and the johansen cointegration tech- nique was used to check for the long-run relationship between model variables. the findings support the conservative hypothesis as a one-way causal link was found from employ- ment to renewable energy consumption in nigeria for the period under consideration. as a result, employment can be created during the construction phase and in the long-run during operations and maintenance of renewable energy projects. this will result in higher supply and consumption of energy by residential consumers and firms. due to the large abundance of reserve for conventional energy sources in nigeria, the energy policy has mostly been geared towards promoting investment in infrastructure to harness oil and gas resources. however, rising population figures, oil price volatility, and air pollution, particularly from gas flaring in the oil industry, necessitates finding an economic and environmentally sustainable solution to the energy crisis, and unemployment through the adaptation of renewable energy resources. the energy crisis that has persisted for several decades has led to the col- lapse of many industries and business enterprises, resulting in alarming levels of unemployment figures. the study recommends that policy makers should introduce incentives such as import duty exemp- tion and a tax holiday in order to propel private investment in renewables particularly in the power- generating segment of the economy. longe et al. ( ) established evidence of positive short-run and long-run relationship between carbon dioxide emissions and energy use pattern in nigeria. diversifica- tion into renewables will provide employment opportunities, particularly in the rural areas, and eliminate the health-related costs associated with air pollution notable with the use of carbon-rich fossil fuels. furthermore, small and medium scale local production of alternative vehicle fuels, such as biodiesel, should be supported by energy policy in nigeria. the nigerian electricity regulatory commission (nerc) should seek to introduce and implement a feed-in tariff scheme in order to facilitate the adapta- tion of renewables and reduce the perceived producer economic risk in renewable energy production. it is widely believed that nigeria, like many oil producing countries, has passed its peaked oil production and, as such, it is imperative the country exploit its vast renewable energy resources in order to sustain economic growth going into the future. lastly, policymakers should seek to implement a strategic plan towards ensuring that new and existing hydropower plants are well equipped with modern technology in order to facilitate energy efficiency, and create employment in the combined effort towards promot- ing an eco-friendly environment. although the findings are meant to complement other empirical studies on the causal link between employment and energy consumption for nigeria, there are still ways to expand on the research in further studies. one such way is to disaggregate renewable energy consumption into its different com- ponents leading to a multivariate causality model, which can provide further insight on the source of renewable energy that exacts greater employment effects on the economy. moreover, another meth- odology other than the surplus-lag approach, such as the bootstrapped p-value, could potentially be used to improve the efficiency of the granger non-causality test. ejae  ( )  - lawan, m. w., gidigbi , m. o.  causal link between employment and renewable energy consumption: evidence from nigeria references akpan, g. e., & akpan, u. f. 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( ). the greenhouse effect, climatic change and rising sea level: implications for development. transactions of the institute of british geographers, ( ), - . doi: . / ejae  ( )  - lawan, m. w., gidigbi , m. o.  causal link between employment and renewable energy consumption: evidence from nigeria rezime: rad je ispitao uzročnu vezu između zapošljavanja, s jedne strane i potrošnje energije iz obnovljivih izvora, s druge strane – u nigeriji, za period - . godine, a oslanjajući se na godišnje podatke o vremenskim serijama. pristup toda-yamamoto granger je korišćen za uzročnu analizu, a johansen tehnika kointegracije je upotrebljena da bi se potvrdila dugoročna veza između varijabli modela. rezultati su podržali hipotezu o očuvanju jednosmerne uzročnosti između zapošljavanja i potrošnje energije, ali nije utvrđen nikakav dokaz o kointegraciji. studija preporučuje da nigerija treba da analizira svoju energetsku politiku, kako bi promovisala privatna ulaganja u projekte obnovljivih izvora energije u pronalaženju održivog rešenja u vezi sa energetskom krizom, kao i stvaranju mogućnosti za zapošljavanje i smanjenju zagađenja životne sredine, koji karakterišu dugoročnu upotrebu fosilnih goriva. ključne reči: obnovljiva energija, uzročnost, zaposlenje, kointegracija, energetska politika. uzroČna veza izmeĐu zapoŠljavanja i potroŠnje obnovljive energije: primer nigerije ejae  ( )  - lawan, m. w., gidigbi , m. o.  causal link between employment and renewable energy consumption: evidence from nigeria hdjen_ .. research article the choice of nuclear energy for ghana as a result of development of its energy production kwame gyamfi , , sylvester attakorah birikorang , emmanuel ampomah-amoako , john justice fletcher, and bernard osei ghana atomic energy commission, national nuclear research institute, p. o. box lg , legon, accra, ghana graduate school of nuclear and allied sciences, university of ghana, p. o. box ae , atomic energy, accra, ghana nuclear regulatory authority, p. o. box ae , atomic energy, accra, ghana correspondence should be addressed to kwame gyamfi; kingbascillus@yahoo.co.uk received april ; revised august ; accepted august ; published august academic editor: ciro aprea copyright © kwame gyamfi et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ghana thought of nuclear energy early in the s but has not been able to realize this dream of generating electricity from nuclear power. ghana’s electricity generation dates back to the gold coast era where the main source of electricity supply (isolated diesel generators) was owned by industrial establishments, municipalities, and other institutions. the electricity sector has developed over the years and has diversified its power generation development to take advantage of available and sustainable sources of energy, mainly hydro, natural gas, liquefied petroleum products, and renewables. these sources sought to increase the electricity production capacity in the country, but unfortunately, it has not been able to catch up with the rate of economic growth, urbanization, industrialization, and rural electrification projects. this has led to ghana’s persistent energy crisis, with inadequate and unpredictable power supply coupled with erratic and prolonged cuts of electricity to homes, industries, and businesses which is now colloquially referred to in the local parlance as “dumsor.” the government of ghana and key stakeholders have therefore decided to add nuclear energy to the energy mix of the country to complement the country’s two main energy sources being hydro and thermal electricity. the details of the developments in the electricity sector leading to the choice of nuclear energy as the best solution for ghana have been outlined. . introduction electrical energy is one of the key determining factors of the economic prosperity of any nation. electricity is essential in every aspect of our daily activities such as lighting, food prep- aration, heating, education, quality healthcare delivery, trans- portation, communication, mining, and powering machines. thus, it serves as the foundation on which every sector of a country’s economy grows. this underscores how critical and necessary electricity is for quality of life in this modern time. . the history of power generation in ghana the generation power in ghana dates back to the preinde- pendence era, where the source of power was predominantly from isolated diesel generator plants distributed in the country. most of the power systems at the time belonged to industrial establishments, municipal assemblies, and other organizations. in , the gold coast railway administra- tion built the first public power generation plant for the oper- ations of the railway sector in sekondi [ ]. the supply was in made available to takoradi. meanwhile, the public works department that was initially in charge of electricity extension had started power supply in accra in from a limited direct current (dc). subsequently, in st november , a large alternating current (ac) project followed the dc source. honorable william omsby-gore on st april opened another generating plant consisting of three horizon- tal single-cylinder oil-powered engines installed in koforidua in the previous year. the extension of power to kumasi begun in , and it became fully operational on st october . hindawi journal of energy volume , article id , pages https://doi.org/ . / / https://orcid.org/ - - - https://orcid.org/ - - - https://orcid.org/ - - - https://orcid.org/ - - - https://creativecommons.org/licenses/by/ . / https://creativecommons.org/licenses/by/ . / https://doi.org/ . / / winneba got a dc supply installed in which was later changed to ac by bringing an existing supply from swe- dru. power supply was extended to tamale in the period - , then in , a new ac was installed to increase their supply. in , cape coast became the next place to enjoy the establishment of a power station. the public works department was initially in charge of extending electricity to the major cities, but on st april , this responsibility was taken over by the electricity department which was established under the ministry of works and housing. in , there were installations of power generating sources at swedru, oda, dunkwa, and bolgatanga. the con- struction of an , -volt overhead transmission line from accra made it possible for nsawam to get power supply in . cities like tema, accra, kumasi, nsawam, temale, and bolgatanga received electricity supply by the year . the chief source of power during this time was diesel gener- ator plants. by the time the akosombo dam project was completed in , there was a total installed capacity of mw. the project was mainly to supply power to the aluminium indus- try; however, it assisted with the country’s switch of major electricity consumed from diesel generators to hydroelectric- ity. it was at the time that the volta river authority (vra), managers of the akosombo hydroelectric power station, started selling electricity to countries like togo and benin. the installed generation capacity was increased by mw in when the kpong hydroelectric power station was commissioned. ghana was hit by a severe drought between and . this caused a long-term shortfall of about % in the total inflow into the akosombo dam. ghana at this time, notwithstanding the increase in generation capacity, suffered its first electricity crisis in . ghana’s generation mix saw the introduction of thermal power plants due to the crisis with a mw facility (tapco and tico) at the takoradi thermal plant. by the end of , the total installed capacity of thermal power plants in ghana has increased to , mw [ ]. the peak load of ghana has been on an ever-increasing path. this necessitated the construction of the mw bui hydroelectric power station (commissioned in december ) to support the peak load. . effect of ghana’s economic growth on its power sector in spite of these increases in the installed and generation capacity, the country’s power sector has, over the past decade, been plagued with power supply challenges due to economic growth, urbanization, industrialization, and rural electrifica- tion projects [ – ] resulting in considerable impact on the economic situation of the country. ghana has experienced an increase of . percent in peak load over the last years, increasing from , mw in to , mw in [ , , ]. this translates into an annual increase of . percent in peak load over the period under review. generation capacity on the other hand has more than doubled over the same period, from , mw in to , mw in the year , an average annual increase of . percent. in addition, the installed generation capacity saw a . percent increase in over the figure of , mw and a further . percent increase in , whereas demand decreased by . percent in before increasing by . percent in . in , a total of , gwh of electricity representing % of the national total was generated at the akosombo, kpong, tema, aboadze, and navrongo facilities. this is a decrease of . percent over the , . gwh generated in . the ghana power system recorded a peak demand of , . mw on november , . this is higher than the peak demand of , mw recorded in , by about percent [ ]. figure shows the percentage energy supply by sources for the year . . ghana’s energy crisis the disparity between demand and supply of power is such that the least disruption in the generation setup results in sys- tem imbalance and recurrent interruptions in power supply and total blackout in some cases [ ]. the electricity crisis has become a household phenomenon in ghana leading to the adoption of the local word “dumsor” to describe the blackout situation. ghana has suffered several episodes of energy crisis in the past, in - , - , / , and - . in the last few years, however, the situation became terrible. from to , the country was plunged into a power crisis which was attributed to poor rainfall in the catchment area of the akosombo dam coupled with high consumption rates from the volta aluminum company (valco) plant. in response to the situation, on a short-term basis, government reduced power supply to valco from mw to mw and subsequently reduced power supply to residential, com- mercial, and industrial consumers. in what may be consid- ered long-term measures, a volta river authority- (vra-) commissioned research recommended the rehabilitation of the tema diesel power plant and the construction of a new thermal power plant. the tema diesel thermal plant was import, . % solar, . % ipp thermal, . % vra hydro, . % vra thermal, . % bui, . % figure : energy supply by sources for the year (source: [ ]). journal of energy in operation in . and between and , the aboadze power plant in takoradi began operations as was recommended by the vra research. another attempt to solve the energy crisis permanently resulted in the agreement between ghana, nigeria, togo, and benin to develop the west african gas pipeline (wagp) to be sponsored by the economic community of west african states (ecowas). the project commenced years after the signing of the project agreement [ ]. despite these initiatives and measures, ghana was hit yet again by another energy crisis from to , which was attributed to drought in the subregion due to what is known as the el nino climatic phenomenon. and between and , a third crisis was witnessed as a result of poor rainfall and the breakdown of the aboadze plant. the government responded to these series of crises by introducing load shed- ding, leasing out operation of the transtema power unit, and importing energy saving lamps, among others. in addition, the government also solicited power from la cote d’ivoire and speeded up construction of the tema thermal power plants and (tt pp). the delayed kpone thermal power plant which started in is estimated to be completed in . ghana also paid its share for the construction of pipe- lines of the wagp project in and had its first supply of gas in december . other plants such as the sunon asogi power plant and the osonor power plant (now cenit of ssnit) are now operational [ ]. recently, there was another long episode of dumsor which lasted till . several factors have been attributed to the persistent blackouts: initially, it was ascribed to a faulty pipeline of the west africa gas project (wagp), which subsequently led to a drastic cut in gas supply from nigeria to power the thermal plants. but now, the reason has been linked to poor rainfalls between and , several years of poor maintenance of the thermal plants, and lack of finance to provide fuel for electricity among others [ ]. this situation arguably threatened and keeps threatening the social-economic sectors of the country leading to con- cerns for the socioeconomic stability of ghana often held as the beacon of peace in west africa. the energy crisis caused many businesses and industries to fold up, and there were many energy-related problems that the country experienced. the world bank ranked electricity as the second most important constraint to business activities in the country and estimated that ghana lost about . percent of gdp during the power crisis [ ]. also, the institute of statistical, social and economic research (isser) at the university of ghana estimated in a study that ghana, on average, lost production worth about us $ . million per day (or us $ . million per month) through the power crisis alone [ ]. this means that the country lost about us $ million ( % of gdp) in due to the power crisis [ ]. as the economy expands coupled with rapid urban sprawl and population growth as well as increase in stan- dards of living, so too will the demand for electricity keep increasing. hence, it is necessary that ghana finds new sources of power generation which can help the nation to satisfy this growing demand. ghana is looking at the integration of low carbon energy options including renewable energies as shown in figure . ghana’s energy policy draft is mindful of the intermit- tent nature of renewable energies, mainly solar and wind, but the policy is aimed at the integration of renewable energy resources in a planned manner to promote the development and use of proven and affordable renewable energy technol- ogies. renewable energies like biomass, solar, and wind ener- gies are being used in ghana in small scales. for the energy supply of ghana to be robust, it is important to consider the contribution of different and reliable sources to the energy mix. therefore, it is needful and advantageous to integrate all available energy sources into the energy mix. lignite g h g e m is si on s (t on ne s c o e /g w h) coal oil natural gas solar pv biomass nuclear hydroelectric average emission intensity range between studies wind figure : lifecycle of greenhouse gas emission intensity of electricity generation method (source: [ ]). journal of energy . the choice of nuclear energy mankind will use more energy in the coming years than it has consumed in its entire history. earlier predictions of energy consumption growth and evolution of energy technologies proved to be wrong as consumption is rising much faster than expected while new sources of energy are not likely to become commercially viable until . fossil fuels are meanwhile growing short. opportunities to build new hydro- power capacity remain limited, while greenhouse effect pre- vention measures impose limitations on burning oil, gas, and coal at thermal power stations [ ]. a potential response to these challenges is nuclear energy, one of the youngest and fastest evolving global industries. having realized this, increasingly more countries are embarking on nuclear power. a typical appearance of a nuclear power plant is shown in figure . the generation of electricity through nuclear energy reduces the amount of energy generated from fossil fuels (coal and oil). this reduction of fossil fuel consumption ben- efits the situation of global warming and global climate change. by reducing the consumption of fossil fuels, we also improve the quality of the air affecting the disease and quality of life. currently, fossil fuels are consumed faster than they are produced, so in the future, these resources may be reduced or the price may increase becoming inaccessible for most of the population. nuclear energy is therefore a perfect alternative to fossil fuels, so the consumption of fuels such as coal or oil is reduced [ , ]. another advantage is the required amount of fuel: less fuel offers more energy. one kilogram of %-enriched fuel- grade uranium releases energy equivalent to the combustion of nearly tons of high-grade coal or tons of oil. it rep- resents a significant savings on raw materials but also in transport, handling, and extraction of nuclear fuel. the cost of nuclear fuel (overall uranium) is % of the cost of energy generated. the reusability of the fuel is also an added benefit of nuclear energy technology. uranium- is not fully burnt up in the reactor and can be reused after regeneration (unlike ash and slag remaining after fossil fuel combustion). with future transition to the closed fuel cycle, the technology will generate zero waste [ , ]. the production of electric energy is continuous. a nuclear power plant is generating electricity for almost % of the annual time. it reduces the price volatility of other fuels such as petrol. this continuity benefits the electrical plan- ning. nuclear power does not depend on natural aspects. it is a solution for the main disadvantage of renewable energy, figure : a typical appearance of a nuclear power plant (source: [ ]). journal of energy like solar energy or eolic energy, because the hours of sun or wind do not always coincide with the hours with more energy demand. the construction of a nuclear power plant and the entire nuclear energy industry have considerable opposition glob- ally. however, the environmental and renewable energy groups in ghana do not oppose the construction of nuclear power plant per se due to the contribution of nuclear energy as a low carbon energy source, but there are diverse views or concerns of the safety of a nuclear power plant in relation to waste or spent fuel management. their conclusions are how- ever largely conjecture. the government of ghana and key stakeholders have therefore decided to add nuclear power as part of a wider project of complementing the country’s two main energy sources being hydro and thermal electricity. nuclear energy was thought of as early as the s when dr. kwame nkrumah laid a foundation to develop both the institutional and the technological development of nuclear power as a source of electricity to complement the hydro- power from akosombo. the first president of ghana, dr. kwame nkrumah made the following remarks on november th at the inauguration ceremony the atomic energy project. he said, “we have therefore been compelled to enter the field of atomic energy, because this already promises to yield the most economic source of power since the beginning of man. our success in this field would enable us to solve the many sided problems which face us in all the spheres of our development in ghana and in africa” [ ]. this was not just a farfetched dream but a proper under- standing and expectation of how scientific enquiry was essen- tial to our progress and how exploring alternative sources of energy was essential for our country. ghana is now working vigorously through the ghana atomic energy commission (gaec) and other stakeholder institutions on the introduction of nuclear power for electric- ity generation. a roadmap has been developed for the commissioning of the first nuclear power plant in as is shown in figure . in december , ghana applied for the iaea’s inte- grated nuclear infrastructure review (inir) mission for the assessment of phase of the nuclear programme. the country then developed the phase inir mission self- evaluation report in . the iaea conducted the inir mission in january . according to the press release by the ministry of energy on thursday, july , , upon nuclear power receiving legal backing, ghana would be the second in africa after south africa to produce electricity from nuclear energy, pro- ducing mw of electricity in the first phase and then , mw in subsequent years [ ]. the technology assess- ment strategies have so far dwelt on pressurized water reac- tors (pwrs), mostly on large reactors, namely, vver , hpr , and apr and small modular reactors. out of these reactors, there is a higher probability that one of them will become ghana’s first nuclear power plant. these reactors are operated using uranium as fuel. pursuant to ghana’s nuclear agenda, studies conducted indicated that there are pockets of uranium deposits in some parts of ghana to serve as nuclear fuel. there are ongoing follow-up studies to assess the commercial viability of these uranium deposits [ , ]. ghana’s capacity to extract and enrich uranium is still under development. for ghana to extract and enrich uranium for the first nuclear power plant is not economically viable for now. when ghana operates a fleet of reactors, then the idea of extraction and enrichment will be of enormous advantage. there is also ongoing discus- sion and consultation among energy policy experts to draw niger, a close neighbouring country who has an abundance of uranium, on board. the idea is for niger to supply the ura- nium to ghana in exchange for electricity. a degree of robustness of the grid is important for the reliable operation of a nuclear power plant. however, gha- na’s current grid has a policy not to allow more than % of the current grid capacity at , mw. therefore, there is an agreement for upgrading the grid system that ghana currently has to enable it to transport electricity generated by a nuclear power plant. . conclusion when nuclear power is added to the energy mix, foreign investors will be attracted to invest in ghana due to the stable power supply that will be available to enhance the smooth operation of their businesses, increasing the income base of the nation through taxes. it can also help ghana to realize preparation of program comprehensive studies & report project feasibility & development phase construction of st npp commissioning & operation of st npp ? ??? n at io na l d ec is io n figure : ghana nuclear power programme roadmap. journal of energy its vision of becoming a power net exporter to many african nations. this will then strengthen the lower middle-income economy status of ghana since the energy deficiencies and hindrances would be eradicated. nuclear power is a capital-intensive venture for ghana but seeing what ghana is likely to gain out of it, it is econom- ically rational that ghana has decided and is working assidu- ously on it as an additional source of power. since the building of a nuclear plant requires a lot of time and huge capital, the growing energy demand is being satis- fied in the meantime with optimal short- to medium-term plans that recommend cost-effective energy options while considering long-term plans with the inclusion of nuclear and other baseload but low-carbon energy technologies as shown in figure . data availability the data used to support the findings of this study are refer- enced within the article. conflicts of interest the authors declare that there are no conflicts of interest regarding the publication of this paper. references [ ] institute of statistical, social and economic research (isser), guide to electric power in ghana, resource center for energy economics and regulation, institute of statistical, social and economic research, university of ghana, accra, . 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[ ] world nuclear association, comparison of lifecycle greenhouse gas emissions of various electricity generation sources, world nuclear association report, london, . [ ] rosatom, benefits of nuclear energy, , february , http://www.rosatom.ru/en/investors/benefits-of-nuclear- energy/. [ ] w. parker, nuclear power, , march , https://www.iop .org/activity/groups/subject/env/prize/file_ .pdf. [ ] s. zafar, advantages and disadvantages of nuclear power pub- lished on october , , , february , https://www .linkedin.com/pulse/advantages-disadvantages-nuclear- power-sultan-zafar. [ ] i. k. dadzie, nuclear energy for ghana, centre for consciencist studies and analyses (cencsa), tema, ghana, . [ ] g. k. quaicoo, nuclear power for ghana: a need, a challenge and result - ghana talks business, , february , https://ghanatalksbusiness.com/nuclear-power-for-ghana-a- need-a-challenge-and-result/. [ ] s. b. dampare, t. k. adu, and a. b. asumadu-sakyi, “undis- covered uranium resources in ghana,” i.a.e.a regional work- shop on “aapplication of united nations framework classification – (unfc- ) for uranium resources”, , johannesburg, south africa, november , . [ ] o. c. oppon, t. k. adu, and a. b. asumadu-sakyi, “prelimi- nary studies on uranium content of some rocks at biakpa, volta region of ghana,” elixir nuclear & radiation physics, vol. , pp. – , . journal of energy http://energycom.gov.gh/files/energy_statistics_ .pdf http://energycom.gov.gh/files/energy_statistics_ .pdf http://vraghana.com/resources/facts.php http://vraghana.com/resources/facts.php http://www.vra.com/ http://documents.worldbank.org/curated/en/ /energizing-economic-growth-in-ghana-making-the-power-andpetroleum-sectors-rise-to-the-challenge http://documents.worldbank.org/curated/en/ /energizing-economic-growth-in-ghana-making-the-power-andpetroleum-sectors-rise-to-the-challenge http://documents.worldbank.org/curated/en/ /energizing-economic-growth-in-ghana-making-the-power-andpetroleum-sectors-rise-to-the-challenge http://documents.worldbank.org/curated/en/ /energizing-economic-growth-in-ghana-making-the-power-andpetroleum-sectors-rise-to-the-challenge https://www.cgdev.org/publication/electricity-situation-ghana-challenges-and-opportunities https://www.cgdev.org/publication/electricity-situation-ghana-challenges-and-opportunities https://www.cgdev.org/publication/electricity-situation-ghana-challenges-and-opportunities http://www.rosatom.ru/en/investors/benefits-of-nuclear-energy/ http://www.rosatom.ru/en/investors/benefits-of-nuclear-energy/ https://www.iop.org/activity/groups/subject/env/prize/file_ .pdf https://www.iop.org/activity/groups/subject/env/prize/file_ .pdf https://www.linkedin.com/pulse/advantages-disadvantages-nuclear-power-sultan-zafar https://www.linkedin.com/pulse/advantages-disadvantages-nuclear-power-sultan-zafar https://www.linkedin.com/pulse/advantages-disadvantages-nuclear-power-sultan-zafar https://ghanatalksbusiness.com/nuclear-power-for-ghana-a-need-a-challenge-and-result/ https://ghanatalksbusiness.com/nuclear-power-for-ghana-a-need-a-challenge-and-result/ 	the choice of nuclear energy for ghana as a result of development of its energy production 	 . introduction 	 . the history of power generation in ghana 	 . effect of ghana’s economic growth on its power sector 	 . ghana’s energy crisis 	 . the choice of nuclear energy 	 . conclusion 	data availability 	conflicts of interest how to create and submit a winning prospect: abstract; ecologic niches of radiolarians, planktonic foraminifers, and pteropods inferred from studies on living forms in gulf of mexico and adjacent waters: abstract association round table and northern alabama through data gathered from oil well logs and measured sections. two deltaic de- pocenters, a carbonate-shelf complex, and a shallow- basin carbonaceous shale unit are the primary deposi- tional systems in the area. three genetic intervals have been identified on the basis of thin marine transgressive carbonate units. the lowest (lewis) interval involves a high-constructive lo- bate delta system whose axes of maximum sandstone thickness extend southeastward from lee and itawam- ba counties, mississippi, as far as tuscaloosa county, alabama. maximum net sandstone thicknesses for indi- vidual lobes average ft ( m). the middle interval includes a western high-destructive wave-dominated delta complex (evans) centered in lee and itawamba counties, mississippi and a more easterly high-destruc- tive wave-dominated delta system (hartselle) in north- western alabama. the hartselle system attains net sandstone thicknesses greater than ft ( m) along a northwest-southeast trend that extends almost to bir- mingham. evans delta-lobe maxima average about half that thickness. the upper interval is dominated by the thick, multistoried muldon high-constructive elongate delta system (rea through carter sandstone units), cen- tered in monroe county, mississippi. on the northeast, and laterally equivalent to the muldon delta, is the ban- gor carbonate shelf. the lewis, evans, and muldon units represent rela- tively thin, cratonic deltas whose sandstone provenance is north-northwest of the black warrior basin, in per- haps a southeastern missouri source area. hartselle ter- rigenous clastic rocks were transported from the north- east and southeast and probably have an appalachian burgess, william j., omni-exploration, inc., radnor, pa. how to create and submit a winning prospect the oil and gas energy crisis will last until other sources of energy become available in abundance. for much of its hydrocarbon supply, the united states now relies on countries which may be subject to political instability. therefore, it would appear that the need for good, drillable prospects within the united states will be present for the next to years, so that the crea- tion and marketing of prospects will continue to be of primary importance to the oil and gas industry and to the country. the drilling deal or prospect may be discussed in terms of its elements: reserves, risk, and terms. practical ways of evaluating reserves include simple volumetric analysis and comparison methods. the study of risk in- quires about the chances for commercial success of a drilling prospect, and involves the geology. risk may be studied in terms of the presence or absence of control for the structural and stratigraphic elements of a pros- pect. the terms of a deal involve cost; the buyer wants to know what he will pay for how much working inter- est which will yield how much revenue interest. a "winning" prospect is one that will sell fast and has a high chance of bringing in a producing field. submit- tals should include exhibits which represent clearly the geological reasons for the prospect. unless the exhibits of maps, cross sections, and other representational data are entirely self explanatory a written description of the prospect should also be included. casey, richard, rice univ., houston, tex., lin- da gust, australian national univ., canberra, austraha, ann leavesley, cities service co., houston, tex., damon williams, radian corp., austin, tex., richard reynolds, rice univ., houston, tex., theo duis, texas a&m univ., marine facility, galveston, tex., and joan mussler spaw, rice univ., houston, tex. ecologic niches of radiolarians, planktonic foramini- fers, and pteropods inferred from studies on living forms in gulf of mexico and adjacent waters living radiolarians, planktonic foraminifers, and pteropods have been collected during - from the waters of the gulf of mexico and adjacent seas using nansen closing nets, duca high-speed plankton nets, water bottles, and plankton pumps by micropaleontolo- gists at rice university. these samples included other shelled microplankton (diatoms, dinoflagellates, silico- flagellates, mollusk larvae, etc), nonshelled microplank- ton (blue-green algae, dinoflagellates, etc), and larger plankton (e.g., copepods, chaetognaths). radiolarian, planktonic foraminifer, and pteropod species composi- tions, diversities, and densities were compared with those of other plankton, and were related to physical and chemical oceanographic parameters. our studies suggest that certain radiolarian, planktonic foraminifer, and pteropod species may be nannoherbivores, bacteri- ovores, detritivores, and/or associated with symbiotic algae and may be characteristic of eutrophic, meso- trophic, or oligotrophic conditions. this information can be applied to studies of the fos- sil record for finer resolution of paleoecologic condi- tions (e.g., paleoproductivities) and for inference of the presence and nature (abundance and diversities) of cer- tain nonfossilizable planktonic components. casey, richard, rice univ., houston, tex., ken mcmillen, univ. texas, marine sci. inst., galves- ton, tex., richard reynolds, rice univ., houston, tex., joan mussler spaw, rice univ., houston, tex., rudy schwarzer, texas southern univ., houston, tex., joel gevirtz, tenneco oil co., houston, tex., and mary bauer, carter oil co., houston, tex. relict and expatriate radiolarian fauna in gulf of mexico—implications the presence of living specimens of spongasterpentas and related spongadiscid forms, buccinosphaera invagi- nata, and certain other radiolarians in plankton samples from the gulf of mexico is evidence of a unique radio- larian population that is composed in part of relict and/ or expatriate forms. these populations may have sur- vived in the gulf because: ( ) the closure of the tethys seaway by the uplift of the panamanian block isolated the equatorial and temperate atlantic waters and blocked radiolarian faunas from entering the pacific review on optofluidic microreactors for artificial photosynthesis review on optofluidic microreactors for artificial photosynthesis xiaowen huang , , , jianchun wang , tenghao li , , jianmei wang , min xu , weixing yu , abdel el abed and xuming zhang* , ,§ review open access address: energy research institute, shandong academy of sciences, jinan, shandong , china, department of applied physics, the hong kong polytechnic university, hong kong, china, the hong kong polytechnic university shenzhen research institute, shenzhen , china, key laboratory of spectral imaging technology, xi’an institute of optics and precision mechanics, chinese academy of sciences, xi’an, shaanxi , china, and laboratoire de photonique quantique et moléculaire, umr , ecole normale supérieure de cachan, centralesupélec, cnrs, université paris-saclay, avenue du président wilson, cachan, france email: xuming zhang* - apzhang@polyu.edu.hk * corresponding author § tel.: + - ; fax: + - keywords: artificial photosynthesis; carbon dioxide fixation; coenzyme regeneration; microfluidics; optofluidics; water splitting beilstein j. nanotechnol. , , – . doi: . /bjnano. . received: july accepted: december published: january this article is part of the thematic series "energy conversion, storage and environmental remediation using nanomaterials". guest editor: w.-j. ong © huang et al.; licensee beilstein-institut. license and terms: see end of document. abstract artificial photosynthesis (aps) mimics natural photosynthesis (nps) to store solar energy in chemical compounds for applications such as water splitting, co fixation and coenzyme regeneration. nps is naturally an optofluidic system since the cells (typical size to µm) of green plants, algae, and cyanobacteria enable light capture, biochemical and enzymatic reactions and the related material transport in a microscale, aqueous environment. the long history of evolution has equipped nps with the remarkable merits of a large surface-area-to-volume ratio, fast small molecule diffusion and precise control of mass transfer. aps is expected to share many of the same advantages of nps and could even provide more functionality if optofluidic technology is introduced. recently, many studies have reported on optofluidic aps systems, but there is still a lack of an in-depth review. this article will start with a brief introduction of the physical mechanisms and will then review recent progresses in water splitting, co fixation and coenzyme regeneration in optofluidic aps systems, followed by discussions on pending problems for real applications. http://www.beilstein-journals.org/bjnano/about/openaccess.htm mailto:apzhang@polyu.edu.hk https://doi.org/ . % fbjnano. . beilstein j. nanotechnol. , , – . figure : (a) a typical plant leaf. (b) chloroplasts inside the plant cells. the average size of the chloroplasts is µm (ranging from to µm). (c) plant cell chloroplast structure. adapted from [ ], copyright biomed central ltd. . (d) thylakoid membrane containing photosystem ii reac- tion centers p and photosystem i reaction centers p . adapted from [ ], copyright michelet, zaffagnini, morisse, sparla, pérez-pérez, francia, danon, marchand, fermani, trost, and lemaire. review introduction the emerging energy crisis, the greenhouse effect and food shortage are devastating problems to be solved, and artificial photosynthesis (aps) is considered to be the most promising and viable method [ - ]. as the name implies, aps is the human replication of natural photosynthesis (nps). nps is a very important process in plants and other organisms which utilize sunlight, water and co to synthesize energy-rich carbo- hydrates [ , ]. the chloroplast is the place where nps occurs. to clearly introduce this organelle, progressively smaller structures (plant cell, chloroplast, thylakoid membrane) of a general leaf are shown in figure a–d. each chloroplast (figure c) contains numerous thylakoids. on the thylakoid membrane, the natural light-harvesting antenna complexes, photosystem ii (ps ii, p ) and photosystem i (ps i, p ), capture the photons and regenerate the coenzyme for carbo- hydrates synthesis (figure d). however, in aps, sunlight is used to create not only the carbohydrates but also other high- value chemicals from abundant resources [ - ]. based on the targeted production, three key areas in the field of aps have attracted intense attention including: photocatalytic figure : basic principles and reactions in artificial photosynthesis, in which the processes of water splitting, co reduction and coenzyme regeneration all utilize electrons on the reduction site. water splitting [ , ], light-driven co reduction [ ] and photo-coenzyme regeneration [ ] (see figure ), which are promising solutions to the energy crisis, greenhouse effect and food shortage, respectively [ , , - ]. beilstein j. nanotechnol. , , – . photocatalytic water splitting aims to convert water into hydro- gen and oxygen. some studies have focused on only the half- reaction for water splitting, while ignoring the other half-reac- tion for oxygen production. this is often called photocatalytic hydrogen production (or generation) and can be regarded as a low-configured version of photocatalytic water splitting. as a renewable and nontoxic gas, hydrogen works not only as a clean fuel but also as a feedstock for important chemical pro- duction, such as ammonia and methanol. similarly, light-driven co reduction has great potential as a clean fuel supplier, espe- cially for the production of methanol or methane [ , ]. addi- tionally, with the consumption of co , aps possibly provides a solution to the greenhouse effect and global warming. unlike human beings, plants have no need to use co as a clean fuel or for to reduce the greenhouse effect. they simply “consume” co to produce carbohydrates (e.g., sugar, cellulose). the global demand for food is increasing dramatically with the con- tinuous growth of the world population [ ]. an increase in population requires more land, water and energy, which in turn decreases the ability to produce food. meanwhile, the require- ment for more land results in the destruction of an increased area of forests, further disrupting the climate change and the greenhouse effect. thus, in a global perspective, the energy crisis, climate change, greenhouse effect, air pollution and food shortage are interconnected. food production in the form of crops relies on the famous calvin cycle, in which the coen- zymes – nicotinamide adenine dinucleotide hydride (nadh) and nicotinamide adenine dinucleotide phosphate hydride (nadph) – play an important role since they work as the reducing power for the biosynthetic reactions. despite its advantages, nps still has a very low energy conversion effi- ciency (typically < %) to capture sunlight and co for the pro- duction of carbohydrates, even after billions of years of evolu- tion, and it is far from its theoretical limit of % [ ]. this gives great room to develop an improved scientific solution to produce basic food materials with high energy efficiency while circumventing all the problems. optofluidic technology has recently exploded with new concepts to enable fine control of light and liquids in microscale structures [ - ]. in fact, nps is naturally an optofluidic system as it is carried out in microscale organisms (chloro- plasts) filled with fluids (see figure ), inferring the feasibility to be mimicked by man-made optofluidic structures. optoflu- idics can promote the reaction efficiencies due to its advantages such as large surface-area-to-volume ratio [ ], fast reaction rate, high-precision manipulation [ ], easy flow control and improved mass and photon transfer in the reaction system [ - ]. the small volume of optofluidic systems reduces the diffu- sion time, dramatically increases the reaction rate on the photo- catalyst surface, and reduces the consumption of expensive photocatalysts and enzymes. therefore, this platform is also useful for the rapid screening of various photocatalysts [ - ]. inexpensive, parallel tests are beneficial for the rare or expen- sive chemical reactions, too [ , ]. moreover, for enzymatic reactions, the flow-based reaction has the great advantage of avoiding product inhibition and cross-reaction [ ]. further- more, cascaded reactions can be divided into different areas where each region can be set with their own optimal reaction conditions such as temperature, ph and concentration. the various photocatalytic nanomaterials [ ] can be designed in different forms in the microreactor inside the optofluidic device, such as in the form of immobilized nanoparticles, films, plugs, droplets, etc. fortunately, many works have contributed to the field of aps. the research efforts have mostly focus on aspects such as de- velopment of novel catalytic materials, modification of the existed catalytic materials (e.g., noble-gas doping, co-catalyst impregnation, noble-metal loading, plasmonic sensitization and z-scheme systems), and optofluidics (or microfluidics) based aps. it should be noted that many efforts have been made to develop bio-photoreactors to culture microorganisms to produce microalgae, bioenergy and biomass [ ]. broadly speaking, these bio-photoreactors also belong to optofluidics-based aps, but they are not covered in this article since many of them use large reactors and are thus not related to microstructures. the following review will start with a brief introduction on the mechanisms of photocatalysis-based aps (water splitting, co reduction and coenzyme regeneration). then we will introduce the representative designs of these three areas with an emphasis on how they help solve the existing problems in their respec- tive area. finally, we conclude with a discussion of the tech- nical barriers that hinder their practical application. basic mechanisms of artificial photosynthesis the aps reaction is not a spontaneous reaction, for example, the gibbs free energy in water splitting increases by kj·mol− , and the required energy could be offered by external light. in principle, a semiconductor photocatalyst (e.g., tio , c n ) absorbs the appropriate photon (hν ≥ e , where e is the bandgap of the semiconductor photocatalyst) to excite an electron in the conduction band, leaving a hole in the valence band. the electron moves to the surface-active sites for surface redox reactions [ ]. the activation equations for water split- ting, co photoreduction and coenzyme regeneration are as follows: ( ) beilstein j. nanotechnol. , , – . ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) equation represents the formation of the electron–hole pair. equation and equation describe the water splitting process. equations – present the co reduction processes and equa- tion is the typical nad+ regeneration. for clearly uncov- ering the chemical mechanism from the reactants to products, some intermediate processes are reasonably ignored. all these three items (i.e., water splitting, co reduction and coenzyme regeneration) utilize the electrons on the reduction site, as shown in figure . however, recombination of photoex- cited electrons and holes may occur. even after the electrons are moved to the surface of photocatalysts, some of them would be wasted due to recombination if the electrons are not used imme- diately for the redox reactions [ - ]. the desirable features of a photocatalyst include wide-range absorption, long-term stability, fast electron–hole separation, and strong redox powers. however, it is difficult to have all of these features in a single photocatalyst. thereby, a simple heterojunction of two or more photocatalysts and artificial z-scheme photocatalytic systems have been developed [ ]. figure a shows the charge carrier transfer in a heterojunction- type photocatalytic system, in which the photo-generated elec- trons and holes are separated in space to suppress the undesir- able recombination. however, when the charge carriers are transferred to lower potentials, the redox ability of these elec- trons and holes is weakened. then, another type of photocata- lytic system is explored, as shown in figure b. the electron acceptor/donor (a/d) pair is introduced to form the z-scheme system, known as the ps-a/d-ps system. since the electron acceptor (a) can react with both the photogenerated electron in ps i and ps ii, the electron donor (d) can react with both the photogenerated hole in ps i and ps ii, and backward reactions would occur, leading to a significant waste of photogenerated electrons and holes. in another design, the a/d pair is replaced by the conductor (c) to form the ps-c-ps system, as shown in figure c. the inserted conductor acts as the electron mediator and forms the ohmic contact with low contact resistance be- tween ps ii and ps i. through the ohmic contact, the photogen- erated electrons from ps ii directly recombine with the photo- generated holes from ps i, reducing the electron transfer dis- tance and avoiding the backward reaction in the ps-a/d-ps system. another simpler design using the solid–solid contact (ps-ps system) is illustrated in figure d. on the contact inter- face, many defects are easily aggregated, causing the energy levels to be quasi-continuous for the ohmic contact. besides, the biomimetic or bioinspired strategy showed the most interesting results. zhou et al. reported a light-harvesting antenna-network inspired polymeric semiconductor-based hybrid nano-system in which water and co were catalyzed to form h and co in this integrated system [ ]. jiang et al. showed a thylakoid-inspired multishell g-c n nanocapsule with orderly stacked nanostruc- tures, which exhibited enhanced visible-light harvesting and electron-transfer properties for high-efficiency photocatalysis [ ]. in summary, the basic mechanism of aps is comprised of three processes: ( ) generation of charge carriers (i.e., electrons and holes), ( ) separation and transfer of charge carriers, and ( ) chemical reactions between surface species and charge carriers. based on this mechanism, various materials have been developed to improve the photocatalytic efficiency [ - ]. furthermore, by taking advantage of the properties of optoflu- idics, many studies with interesting improvements have been re- ported. we will now review these in terms of water splitting, co reduction and coenzyme regeneration. microreactors for artificial photosynthesis an optofluidic microreactor is a versatile platform for combin- ing new materials and characterizing their reaction kinetics without expensive bulky setups. recent developments in optofluidics has allowed for the advancement of aps technolo- gy by use of the microreactors. water splitting in the early studies on optofluidic-based water splitting, the optofluidic device often employed sol–gel catalysts on planar channels. for example, erickson et al. demonstrated a planar setup with tio –pt to process the water splitting reaction [ ]. beilstein j. nanotechnol. , , – . figure : schematic diagrams of heterojunction and z-scheme systems. transfer of charge carriers in (a) the heterojunction-type photocatalytic system, (b) the z-scheme ps-a/d-ps system, (c) the z-scheme ps-c-ps system, and (d) the z-scheme electron ps-ps system. adapted from [ ], copyright wiley-vch verlag gmbh & co. kgaa. ps stands for photosystem. the reaction was mediated by i−/io − redox pairs, belonging to the ps-a/d-ps system. after the reaction, the optofluidic device showed ≈ -fold improvement in the reaction rates as compared to the traditional bulk method. nevertheless, this planar design still showed an unsatisfactory performance of hydrogen generation due to a limited active surface area and low mass transfer rate. in another work, wang et al. proposed an optofluidic microreactor with staggered micropillars in the reaction microchamber [ ], as shown in figure . such struc- ture has four favorable features: ( ) enlarged surface area for loading catalysts; ( ) perturbation to the liquid flow for rapid mixing; ( ) shortened transfer length and enhanced mass transfer; and ( ) increased active surface area. with these advantages, the reaction rate could be increased by % as compared to the conventional planar microreactors. however, a new problem emerges: the direct coating methods are unable to load catalysts firmly and uniformly on the pdms substrate. zhang et al. proposed a new casting transfer method for loading catalysts on the pdms substrate [ ], as shown in figure . this method exhibited critically higher durability and better hydrogen production rate than the conventional ones. co reduction optofluidic microreactors have been firstly applied for water purification [ ], water splitting [ ], photocatalytic fuel cells [ ] and then co reduction [ ]. chen et al. combined the optofluidics with the tio /carbon paper composite membrane for the photoreduction of co [ ], as shown in figure . using this device, they studied the factors that affected the methanol yield (such as flow rate, light intensity and catalyst loading) and obtained a high reduction result in comparison to the reported data. other membrane-based reactors were reported as well, for instance, mesoporous cds/tio /sba- @carbon paper com- posite membranes [ ] and copper-decorated tio nanorod thin films [ ]. beilstein j. nanotechnol. , , – . figure : (a) schematic of the high-surface-area optofluidic microreactor with micropillar structure. (b) staggered micropillars in the reaction chamber. (c) fabrication procedure of the optofluidic microreactor with the catalyst-coated micropillars. reprint with the permission from [ ], copy- right elsevier ltd. figure : (a) schematic of the high-surface-area optofluidic microreactor with micro-grooved structure. (b) fabrication procedure of the optofluidic microreactor with the catalysts on the pdms substrate. adapted from [ ], copyright elsevier ltd. in addition to the pdms/pmma-based microchannel reactors, bacterium has been shown to be a good microreactor as well. yang et al. developed a hybrid approach that combined highly efficient light harvesting of inorganic semiconductors with biocatalysts [ ]. as shown in figure , they induced a non- photosynthetic bacterium with biologically precipitated cds nanoparticles, enabling the photosynthesis of acetic acid from co . the cds nanoparticles functioned as the light harvester. this self-augmented biological system selectively produced acetic acid continuously over several days, demonstrating a novel co reduction microreactor. coenzyme regeneration aps-based coenzyme regeneration has attracted less attention as compared to water splitting and co reduction [ ], but sig- nificant progress had already been made before it was combined beilstein j. nanotechnol. , , – . figure : schematic of the optofluidic membrane microreactor for photocatalytic co reduction. adapted from [ ], copyright elsevier ltd. figure : (a) bacterium–cds hybrid system that has cds nanoparticles on the bacterium membrane (yellow particles). (b) pathway diagram for the light harvesting and the photosynthetic conversion of co to acetic acid with the bacterial enzyme system. adapted from [ ], copyright amer- ican association for the advancement of science. with the optofluidics [ ]. park et al. developed cds quantum- dot-sensitized tio nanotube arrays for the photo-regeneration of nicotinamide cofactors [ ]. they also used sio -supported cds quantum dots for sustainable nadh regeneration [ ]. however, the toxicity and photoinduced instability of cds limited the application of this material. liu et al. used carbon nitride (c n ), a stable and environmental friendly material [ ], for nadh regeneration [ - ]. for example, one bioin- spired method utilized the diatom as the c n formation templet, enlarging the specific surface area for enhanced light trapping and scattering and eventually high photocatalytic effi- ciency [ ]. this research is mostly based on the slurry method. optofluidics-based coenzyme regeneration appeared only in recent years. park et al. presented an optofluidic device that incorporated quantum dots and redox enzymes for photo-enzymatic synthe- sis [ ]. as shown in figure , the microchannel was separated into two parts by a valve, the light-dependent reaction zone for nadh regeneration in the upstream of microchannel and the light-independent zone for enzymatic synthesis in the down- stream. our group reported a optofluidic chip-based artificial ps i using a novel one-step fabrication method (see figure ), which outperformed the traditional methods in several aspects in terms of facile synthesis, promotion of the combination of g-c n and electron mediator through π–π stacking, in addition to a significantly enhanced coenzyme regeneration rate [ ]. coenzyme regeneration is also of great importance in co reduction with the help of enzymes. formaldehyde dehydroge- beilstein j. nanotechnol. , , – . figure : microfluidic aps platform that incorporates quantum dots and redox enzymes for photoenzymatic synthesis. (a) concept and (b) besign of microreactor in which the cofactor regeneration takes place in the light-dependent reaction zone and the enzymatic synthesis in the light-independent zone. adapted from [ ], copyright royal society of chemistry. figure : microfluidic chip based artificial photosystem i. (a) schematic illustration of the ps i reaction center. (b) one-step fabrication process of the immobilized artificial ps i (iapsi) in the form of the g-c n -m film. (c) simple procedures to fabricate the iapsi microreactor. (d) photograph of the as-fabricated iapsi microreactor, in which the inset presents the leaf-like shape of g-c n -m. the scale bar is mm. adapted from [ ], copyright the royal society of chemistry. beilstein j. nanotechnol. , , – . nase is a typical one that selectively achieves methanol forma- tion from co with the depletion of nadh to nad + [ ]. the continuous regeneration of nadh enables the continuous reduction of co . conclusion aps is a promising way to utilize solar energy and a prospec- tive solution for the energy crisis, greenhouse effect and coen- zyme utilization. an effective photocatalyst is expected to have wide-range absorption, long-term stability, fast electron–hole separation, and strong redox power. the heterojunction and z-scheme systems are the important most research results to date. based on these systems, various materials have been de- veloped for the improvement of photocatalytic efficiency [ - ]. besides, biomimetic or bioinspired strategies for the syn- thesis of semiconductor materials represents a significant advancement in the development of high-efficiency and cost- effective visible-light photocatalysts for solar energy conver- sion [ - ]. given the advantages of optofluidic systems, more studies with significant improvement are expected. the optofluidic planar microreactor has shown to be a versatile platform for superior performance in water splitting, co reduction and coenzyme regeneration. however, there are still some problems. one problem is the limited production amount caused by the small volume of the microreactor. for high throughput and adequate production, a feasible solution may involve the combination of two approaches: to parallelize the microreactors to form an array and to enlarge the microchannel in the lateral direction into a planar chamber [ , - ]. another problem is the lack of an integrated on-chip detection method. after the reaction, the production products should be collected and then analyzed by the bulky, expensive, traditional off-chip equipment, such as a uv–vis spectrometer or high-per- formance liquid chromatography and gas chromatography mass spectrometer. as demonstrated by our group in a work on microfluidic water purification [ ], on-chip detection would make it convenient to monitor the reaction process in real time, to probe the intermediate reactions/productions and to study the reaction kinetics. in view of the many merits induced by optofluidics, the microreactors may be also introduced to other aps systems such as nitrogen fixation (e.g., nh ) [ ], ch [ - ], co [ - ], formaldehyde [ , ], methanol [ - ], and formic acid [ ]. more profound and meaningful work is ex- pected to appear in the field of optofluidics-based aps since the optofluidic devices are versatile and can be integrated together with other functions, for instance, deoxygenation, temperature control, electricity/magnetic field and pressure [ - ]. acknowledgements this work is supported by shandong province natural science foundation (no. zr bb ), the youth science fund of shandong academy of sciences (no. qn ), national natural science foundation of china (no. , no. ), research grants council of hong kong (n_polyu / , polyu / e, polyu / e, polyu and polyu / e), and hong kong polytechnic university (grants g-yn , g-ybbe, g-ybpr, -bcal, -zvaw, -ze , a-pm , -ze and -zvgh). orcid® ids xuming zhang - https://orcid.org/ - - - references . turek, a. k.; 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hsu, y.-w.; hsieh, h.-y.; chen, s.-y.; fan, s.-k. sci. adv. , , e . doi: . /sciadv. .wang, l.; liu, w.; wang, y.; wang, j.-c.; tu, q.; liu, r.; wang, j. lab chip , , . doi: . /c lc f .dunkel, p.; hayat, z.; barosi, a.; bchellaoui, n.; dhimane, h.; dalko, p. i.; el abed, a. i. lab chip , , . doi: . /c lc j .ngo, h. m.; lai, n. d.; ledoux-rak, i. nanoscale , , . doi: . /c nr h license and terms this is an open access article under the terms of the creative commons attribution license (http://creativecommons.org/licenses/by/ . ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. the license is subject to the beilstein journal of nanotechnology terms and conditions: (http://www.beilstein-journals.org/bjnano) the definitive version of this article is the electronic one which can be found at: doi: . /bjnano. . https://doi.org/ . % fsciadv. https://doi.org/ . % fc lc f https://doi.org/ . % fc lc j https://doi.org/ . % fc nr h http://creativecommons.org/licenses/by/ . http://www.beilstein-journals.org/bjnano https://doi.org/ . % fbjnano. . 	abstract 	review 	introduction 	basic mechanisms of artificial photosynthesis 	microreactors for artificial photosynthesis 	water splitting 	co reduction 	coenzyme regeneration 	conclusion 	acknowledgements 	orcid ids 	references p-graph approach to optimal allocation of electricity to economic sectors in crisis conditions energy procedia ( ) – available online at www.sciencedirect.com sciencedirect - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of icae doi: . /j.egypro. . . the th international conference on applied energy – icae p-graph approach to optimal allocation of electricity to economic sectors in crisis conditions k. b. avisoa*, c. cayamandaa, f. d. solisb, m. a. b. promentillaa , k. d. s. yub, j. r. santosc and r. r. tana a chemical engineering department, de la salle university, taft avenue, malate, manila, , philippines b school of economics, de la salle university, taft avenue, malate, manila, , philippines c department of systems engineering, the george washington university abstract rational allocation of scarce resources in a crisis is an integral part of risk management. in the case of energy systems, for example, the onset of climate change is expected to increase the frequency of extreme weather events which will further affect not only the reliability of electricity transmission and fuel resource delivery but also test the integrity of energy infrastructure systems. electricity supply is essential to all economic sectors and the onset of an energy crisis resulting from a calamity, an accident, an infrastructure failure or a political dispute will affect the productivity of the entire economy. furthermore, the interdependencies between sectors can cause “ripple effects” to occur. input-output models are an established methodology for quantifying such linkages in an economic system. during a power crisis, it is essential to provide a rational basis for allocation of limited energy supply in order to minimize its economic ripple effects. the best allocation for damage control can be determined by representing an input-output system as a p-graph model. the latter is a graph-theoretic approach originally developed for chemical process design applications, and the analogous problem structures allow it to be used for the optimal allocation of electricity to various economic sectors in the event of a power crisis. we demonstrate the methodology using a case study based on philippine input-output data. © published by elsevier ltd. selection and/or peer-review under responsibility of icae keywords:energy crisis; allocation; p-graph; input-output analysis . introduction input-output (i-o) analysis was originally developed for the analysis of highly interconnected economic sectors for purposes of forecasting and policy design [ , ]. such i-o models represent economic systems via a system of linear equations that capture interdependencies. more recently, i-o * corresponding author. tel.: + - - ; fax: + - - . e-mail address: kathleen.aviso@dlsu.edu.ph. © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of icae http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf k.b. aviso et al. / energy procedia ( ) – based optimization models have been proposed for crisis management, such as to determine optimal allocation of scarce resources following a disaster [ - ]. analogous approaches have been proposed for infrastructure systems [ , ]. in this work, we propose an alternative approach towards solving such problems using a graph-theoretic method known as p-graph, which was originally developed for chemical process design applications [ ]. it has since been used for various network optimization problems such as supply chain design; a recent paper reviews the most important developments in the field [ ]. a software implementation of this methodology is also available [ ]. in this paper, we present the first attempt to utilize p-graphs for allocation of scarce energy resources in an economic system. the rest of the paper is organized as follows. section gives the formal problem statement while section gives an overview of p-graph methodology used here. section shows a philippine case study to illustrate the methodology and section gives conclusions and future works. . problem statement the problem statement may be formally stated as follows: given an economic i-o system comprised of n sectors and n commodities, and given a crisis event that creates a sudden shortage of the kth commodity, the problem is to determine the optimal allocation of commodity k in the system so as to minimize total reduction of gross domestic product (gdp). . p-graph methodology another method that can be used besides the leontief’s i-o model is to apply graph-theoretic approach for developing input-output model such as p-graph framework. process graph or p-graph framework is used to determine the optimal solution of a process network system based on graph theory and combinatorial algorithms [ ]. p-graph is used in several applications such as optimization of process systems, reduction of emissions and wastes, identification of reaction pathways, and sustainable energy supply chain [ ]. p-graph is the graphical representation of matrix calculations such as mixed-integer linear and nonlinear programming (milp and minlp) to solve process synthesis problems. with this ability, p-graph can be used to solve i-o models for estimating risk assessment and optimal allocation of resources. . case study this case study is based on the current power crisis in mindanao, the southernmost major island of the republic of the philippines. chronic electricity shortage is experienced in this island during the dry season due to over-dependency on hydroelectric power. this situation is expected to be compounded by climate change. we consider the case of region xi, which comprises the most economically vibrant region of the island. a low-resolution, -sector i-o model of the economy of this region was derived from the most recent official national i-o model [ ] using established regional disaggregation and sector aggregation methods [ ], as shown in table with the total output and final demand rounded off to the nearest thousand pesos. k.b. aviso et al. / energy procedia ( ) – table . technical coefficients, total outputs and final demands for of -sector i-o model (normal state) agriculture industry services electricity generation final demand (‘ php) total output (‘ php) agriculture . . . . , , industry . . . . , , services . . . . , , electricity generation . . . . , , the economic flows of the system in its baseline state are shown in figure a. in the event of a % power shortage with the final demand of all sectors remaining the same, the optimal allocation of electricity to minimize gdp loss in the system can be determined via the accelerated branch-and-boud method (abb) within the p-graph model. this result is shown in figure b, with a corresponding . % reduction in gdp relative to the normal state. table shows the summary of the experienced reduction in final demand and total output resulting from the % power shortage relative to the normal state total output. it can be seen that the % shortage in electricity has resulted in a reduction in total output for all other sectors by virtue of their interdependence. the industry sector experiences the second highest loss of . % next to the electricity sector while the agriculture sector has the least reduction in total output of . %. however, even with the shortage in electricity, the final demands of the agriculture, industry and services sector were still satisfied while the demand of the electricity sector was reduced by . %. (a) (b) figure . economic flows for (a) normal and (b) crisis state, units in , pesos table . reduction in final demand and total output resulting from the % power shortage relative to normal state total output economic sector % reduction in final demand % reduction in total output agriculture . . industry . . services . . electricity . . over-all . . k.b. aviso et al. / energy procedia ( ) – . conclusion a p-graph based approach for the allocation of scarce energy resources under crisis conditions has been presented. the graph-theoretic approach allows for a visual representation of highly interconnected input-output systems, and also enables efficient identification of a globally optimal solution. this technique is demonstrated with a case study on power shortages in the southern philippines. in reality, more complex interactions between system components will have to be considered if a higher degree of resolution is desired in the results. furthermore, since the approach identifies the key sectors which must be prioritized during a crisis, this approach can be utilized for developing strategies for disaster preparedness. future work will focus on the integration of the p-graph approach within a comprehensive decision analysis framework for crisis management. acknowledgements we would like to acknowledge the commission on higher education- philippine higher education research network (ched-phernet) through its sustainability studies program for financial support. references [ ] leontief, w. 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[ ] national statistical coordination board. www.nscb.gov.ph/io/default.asp (accessed may , ). biography krista danielle s. yu, phd is an assistant professor at the school of economics, de la salle university manila, philippines. her research interests include input-output analysis, computable general equilibrium modelling and their applications to disaster risk management. <c a c f dbfb b f e d> j. microelectron. packag. soc., ( ), - ( ) https://doi.org/ . /kmeps. . . . print issn - online issn - recent advances in thermoelectric power generation technology ashutosh sharma , jun hyeong lee , kyung heum kim and jae pil jung ,† dept. of materials science and engineering, university of seoul, , seoulsiripdae-ro, dongdaemun-gu, seoul , korea duksan himetal co. ltd., , muryong -ro, buk-gu, ulsan , korea (received february , : corrected february , : accepted march , ) abstract: thermoelectric power generation (teg) technology with high figure of merit (zt) has become the need of the modern world. teg is a potent technology which can tackle most of the environmental issues such as global warming, change in climatic conditions over the globe, and for burning out of various resources of non-renewable energy like as petroleum deposits and gasolines. although thermoelectric materials generally convert the heat energy from wastes to elec- tricity according to the theories seebeck and peltier effects yet they have not been fully exploited to realize their potential. researchers are focusing mainly on how to improve the current zt value from to or even by various approaches. however, a higher zt value is found to be difficult due to complex thermoelectric properties of materials. hence, there is a need for developing materials with high figure of merit. recently, various nanotechnological approaches have been incorporated to improve the thermoelectric properties of materials. in this review paper, the authors have performed a thorough literature survey of various kinds of teg technology. keywords: thermoelectric, figure of merit (zt), power generation, seebeck effect, nanotechnology, energy . introduction the modern world is facing various energy crisis such as limitation of non-renewable resources, global warming, air and water pollution that are affecting the life of common people. ) according to one report, approximately seventy percent of energy into the planet earth is dissipated as heat due to dangerous gaseous emissions. a major fraction of the energy wastes comes from the fuel in production, trans- port and public sectors. ) the whole world is looking for the clean and sustainable sources of energy. the develop- ment in clean energy sources has various obstacles like abundance, cost, efficiency and climate. though the well- known energy from the sun is a better source clean energy yet it is constrained by the efficiency and availability of the sunlight. the conversion of waste heat using various energy converters and storing the energy for future use can be a possible solution to solve the above problem up to some extent. teg technology can be considered as a powerful alternative to tackle the energy crisis all over the world. ) the tegs are generally the power devices which are used to convert the heat from waste to the useful electricity. these tegs use temperature gradient as input and provide the electrical energy as output based on the thermoelectric principles like seebeck and peltier effects. ) . thermoelectric science and technology the thermoelectric science is based on the principle of energy conversion, from thermal energy to electricity or vice versa by thermoelectric materials based on various principles (seebeck and peltier effects) identified by thomas johann seebeck in and jean charles athanase peltier in . - ) . . seebeck effect the seebeck effect tells us that if a thermal gradient is applied to a thermoelectric material, a voltage can be gen- erated across the material. for example, if we connect two thermocouples or dissimilar metals a and b as shown in fig. (a). , - , - ) if the two junctions, hot and cold junctions have different temperatures (ta>tb), then there will be a voltage gener- ated (v) across junctions due to charge difference in the material. the relationship between the voltage developed and the temperature difference across the hot and cold †corresponding author e-mail: jpjung@uos.ac.kr © , the korean microelectronics and packaging society this is an open-access article distributed under the terms of the creative commons attribution non-commercial license(http://creativecommons.org/ licenses/by-nc/ . ) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 특집: recent advances in thermoelectric ashutosh sharma, jun hyeong lee, kyung heum kim and jae pil jung 마이크로전자 및 패키징학회지 제 권 제 호 ( ) junctions can be expressed as. - ) ⇒ v = s(ta-tb) ( ) ⇒ v = sΔt ( ) where s = seebeck coefficient between the two metals, v = thermoelectric voltage and Δt = ta-tb, temperature difference across the junction (fig. (b)). the sign of see- beck coefficient depends upon the direction of flow of the charge careers from one junction to other. . . peltier effect the peltier effect is just reverse of the seebeck effect. for example, one junction is cooled and other one is heated after a potential difference is set up in a circuit of metals a and b as shown in figure . suppose, in a circuit, two pieces of a metal plate are connected to a semiconducting wire joined by a battery. then the junction gets heated where the current flows from metal to semiconductor, and cooling is noticed at the junction where the current flows from semiconductor to metal. the peltier coefficient is expressed in terms of heating flow at one junction and a rate of cooling at the other junction. in other words, peltier coefficient can be expressed as mathematically, - ) ⇒ П = i/q, ( ) where, q = heat flow, i = electrical current generated. . factors affecting thermoelectricity . . seebeck coefficient the seebeck coefficient can be defined as a property of a material caused by seebeck effect is the amount of voltage generated between the two thermocouples per unit tem- perature difference. - ) seebeck coefficient depends on the electronic band structure of the materials and the density of states (dos) in the range of fermi level. higher dos and moderate carrier concentration will produce a larger see- beck coefficient. the type of the charge careers (holes or electrons) will determine the nature of the sign of seebeck coefficient. ) . . electrical conductivity the electrical conductivity of a material is expressed in the form of equation: σ = neμ, ( ) where, σ is the electrical conductivity, n is the charge carrier concentration per unit volume, e is the electronic charge, and μ is the mobility of the charge careers as deter- mined from the hall experiments. the charge careers and mobility are dependent on the temperature. the conductiv- ity is further affected by various types of impurities in the material which act as a barrier to flow of the electrons and scatter them inside the crystal lattice. metals are good con- ductors of electricity ( mho/m), semiconductors ( - to mho/m) and insulators ( - and - mho/m) and the values may vary along with temperature and impurity amount present in that materials. - ) . . thermal conductivity the ability of a material to conduct heat by lattice vibra- tions or phonons. ) therefore, materials of high thermal conductivity are used for heat sink source whereas low thermal conducting materials are used for insulation. ther- mal conductivity is also a function of temperature and can be expressed as: ( ) where q is the amount of heat flow through the mate- q k dt dx ------ ⎝ ⎠ ⎛ ⎞ –= fig. . (a) schematic diagram of a basic thermocouple, (b) seebeck effect, and (c) peltier effects. , , , ) recent advances in thermoelectric power generation technology j. microelectron. packag. soc. vol. , no. ( ) rial, is the thermal gradient across the material and kl is the coefficient of thermal conductivity of the material. ) the negative sign indicates that heat flows from hot to cold region. the total thermal conductivity of a material is given by the kt = kel + kl ( ) where, kel is the electronic contribution tyo thermal con- ductivity of the material and kl is the due to the lattice vibrations. - ) the weidemann franz law tells us that electronic ther- mal conductivity is related to the lorentz number accord- ing to the relation: kel = lσt, ( ) where σ is the electronic conductivity, t is the absolute temperature and l is the lorenz number. it can be con- cluded that kel is a function of σ and t and therefore, form equation ( ), the kel also depends upon charge career den- sity (n) and their mobility (μ). ) the lattice contribution of thermal conductivity depends upon the phonon vibration characteristics. according to the kinetic theory of gases ( ) where, c is the heat capacity of the metal, v is the veloc- ity of phonon vibrations and l is the mean scattering free path. - ) . . figure of merit the conversion efficiency of the teg device is measured in terms of the figure of merit (zt). from carnot equation, the maximum efficiency of teg is given by: ) ( ) where thot and tcold are the hot and cold junction tem- peratures, ∆t is given by thot − tcold, and tmean is given by (thot + tcold)/ , respectively. the carnot efficiency is given by Δt/thot multiplied by a reduction factor: z = s ρ− κ− , ( ) where s, ρ, and κ are the seebeck coefficient, electrical resistivity, and thermal conductivity, respectively. the dimensionless figure of merit (zt) has been utilized since as a design parameter to achieve highly efficient materials. high zt value (zt ≈ - ) materials convert a greater amount of waste heat to power. ) in the past vari- ous researchers have been discovered that exhibit zt > and still there is a need for increasing this zt value for realizing full potential of this technology. the conventional thermoelectric materials includes pb-te or bi-te based compounds which are expensive, and pose a threat to our environment due to their toxicity. other class of thermoelec- tric materials include mg-based materials which are cheaper but they have a poor figure of merit which makes them unsuitable for electricity conversion in various applications. figure of merit (zt) can be enhanced by controlling various factors like materials electronic structure, charge career con- centration and lattice vibrations characteristics. - ) now a days, nanotechnology have played a major role in enhancing the zt value to a larger extent due to the novel properties of nanoparticles by control of crystallographic texture, modula- tion by doping, creating nanograins, dispersion of nanoparti- cles into the thermoelectric materials. ) . thermoelectric materials there are three categories of thermoelectric materials depending on the temperature range of applications. . low temperature range (< oc): bi based alloys . moderate temperature range ( oc- oc): pb based alloys . high temperature range (> ˚oc): si-ge based alloys etc. . . conversion efficiency commercial thermoelectric materials have zt≈ . on laboratory scale, thermoelectric materials have zt≈ or approach to . only the materials (zt values above or approach to ) have capability to convert into some useful electrical energy from waste heat with sufficient conver- sion efficiency as shown in figure . ) . . material selection semiconductor materials are suitable for thermoelectric generators because of their high charge carrier mobility, moderate charge carrier concentration. a high conductivity of the metals causes lower seebeck coefficient and hence the generated power is low. an increase in electronic ther- mal conductivity of metals when temperature rises due to high electron carrier concentration which may cross a threshold of /cm and may degrade the zt value. - , - ) dt dx ------ ⎝ ⎠ ⎛ ⎞ k ---cvl= n max tΔ t hot --------- zt mean + – zt m + t cold t hot ----------+ -----------------------------------------= ashutosh sharma, jun hyeong lee, kyung heum kim and jae pil jung 마이크로전자 및 패키징학회지 제 권 제 호 ( ) various approaches have been tried to optimize the thermo- power, for example, by alloying, doping, nanostructured thermoelectric, nanocomposites approach, nano thin films, segmented thermoelectric etc. the fabrication route also affects the thermoelectric characteristics. various routes like mechanical alloying (ma), melting and casting process, microwave fabrication routes, hot pressing and spark plasma sintering (sps) tech- niques. . . developments in thermoelectric materials various types of thermoelectric materials have been developed so far and still there is a need to approach ideal thermoelectric material. thermoelectric materials accord- ing to their composition and structure are classified as chalco- genides, clathrates, skutterudites, half-heusler (hh) alloys, silicides, oxides and zintl phase materials etc. - ) some examples of thermoelectric materials are shown in table . most of these are based on bi, sb, and te which are highly expensive, toxic and unstable at high temperature. polymers have also been investigated as cheaper alterna- tive due to their light weight and flexibility and abundance. however, the zt value is rather lower due to their low electrical conductivity and seebeck coefficient and their use is limited. . nanotechnological approach to thermoelectric materials with the emergence of nanotechnology which operates when the size of the material reaches at one or its dimen- sions < nm. for example, the nanomaterials can be produced in the form of nanopowders, or nanotubes/ fig. . conversion efficiency of thermoelectric materials at cold junction temperature of k. ) fig. . figure of merit of a number of thermoelectric materials. - ) recent advances in thermoelectric power generation technology j. microelectron. packag. soc. vol. , no. ( ) nanowires, nano-rods and nanocoatings where the grain size falls in the nano-regime. the nanostructured thermo- electric materials have better figure of merit and conver- sion efficiencies as compared to the bulk counterparts. - ) the reason why the zt value is enhanced is due to the large decrement in the thermal conductivity as a conse- quence of the increased phonon scattering at the grain boundaries and higher power at higher temperatures. - ) various kinds of nanostructured materials have been developed using nanotechnology, such as, nanocomposites, ultrafine grained materials and super lattices. in case of nanocomposites, the selection of the reinforcement and the dispersion process must be optimized before actually used in practice. in nanocomposites, at least one phase should be in the nanorange. the incorporation of nanoparticles can solve the problem due to the formation of new inter- face in the matrix. however, the nanoparticles are very high surface active entities. their selection as a reinforce- ment is critical for avoiding the segregation and hence a depression in thermopower. , , ) . thin film thermoelectric technology due to the miniaturization of the electronic circuits and systems, the amount of heat dissipation is large enough to cause thermal breakdown of the device and eventually fail- ure of entire device. traditional or bulk thermoelectric devices have been used for years to control the temperature of electronics where the cooling of the entire device is an efficient method for thermal management leading to the oversizing of the thermoelectric device. the modern thin film thermoelectric technology targets the heat flux source to provide thermal control. such types of thermoelectric device incorporate nanostructured p and n type materials in the form of a coating, typically to μm thick, over μm for traditional devices. this creates a huge heat flux around times as compared to traditional ones. gary et al synthesized bi te superlattice based thin thermoelectric device using metal organic chemical vapor deposition tech- nique and obtained cooling fluxes of w/cm over com- mercial w/cm - ) however, there are various barriers in thin film technology which need to be sorted out for full potential of this technology. for example, electrical contact resistance between metal electrodes and the semi- conductor layers can be comparable to that of the thermo- electric element itself, thus increasing the overall electric resistance of the thermoelectric device and reducing the cooling flux. ) . magnesium based thermoelectric magnesium based thermoelectric materials have attracted the researchers in the past to overcome the issue of cost, toxicity and light weight compared to the bulk tra- ditional thermoelectric materials (bi te , pbte and cosb ). mg is the light metal having density ( . g/cm ) versus most popular aluminum ( . g/cm ) and iron ( . g/ cm ). mg based alloys are high strength and low weight, moderate melting points and their intermetallic compounds or alloys form zintl phase with a large electronegativity gap. ) zintl phases are the potential candidates for obtain- ing high zt value in thermoelectric materials, e.g. (eu / yb / ) -xcaxmg bi . mg x (x=si, ge, sn, si-sn, si-ge, etc) compounds have shown higher figure of merit as com- pared to the si-ge and β-fesi [ - ]. it is also notewor- thy point that band gap range of mg based thermoelectric materials are close band gaps of semiconductor materials as shown in table . however, the synthesis of these mg (si, sn) single phase is difficult due to the high vapor pressure and chemical table . figures of merit of developed bulk thermoelectric materials , ) materials examples zt at temperature metal oxides bi doped ca co o > at oc chalcogenides ti bite . at oc clathrates ba ga ge . at oc half heuslers hf . zr . nisn . sb . . at oc skutterudites ba . ni . co . sb . at oc polymers polyacetylene polyprrole polyaniline pedot . - . at oc . at oc . at oc . at oc table . band gaps for different mg based thermoelectric materials. , ) material band gap (ev) mg si . mg ge . mg sn . mg si . sn . . mg si -xgex . - . sige . pbte . bi te . ge . si . ashutosh sharma, jun hyeong lee, kyung heum kim and jae pil jung 마이크로전자 및 패키징학회지 제 권 제 호 ( ) activity of mg as well as large gap in melting points of the constituents. ) the stability and performance of mg (si,ge) is better than mg (si, sn) but is highly expensive due to cost of ge. application of nanotechnology has been also found to increase the figure of merit of theses alloys via nanopar- ticles inclusion in the matrix. . conclusion thermoelectric materials are the backbone of energy sec- tor to avoid the energy crisis in the coming years worldwide. materials with high figure of merit categorized as metals, polymers, chalcogenides, clathrates, skutterudites, half-heu- sler alloys, and silicides. the task to develop the mg based thermoelectric is challenging in view of the purity, melting point, 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ro, buk-gu, ulsan, korea • research interests: soldering, thermoelectric module • email: khkim@oneduksan.com • jae pil jung • department of materials science and engineering university of seoul, seoul- , korea • research interests: microjoining, electroplating, brazing fillers, solder-joint reliability, metal matrix nanocomposites, lead free soldering • email: jpjung@uos.ac.kr food production and the energy crisis: a comment the article by pimentel et al. ( ) raises serious questions concerning the energy-intensive path of agricultural development that has been followed by the developed countries of western europe, japan, and the united states and that is now being adopted by a number of developing countries. similar concerns have been expressed by hirst ( ) and by steinhart and steinhart ( ). in addition, the pimentel article has been cited to support more extreme conclusions than the authors themselves might espouse ( ). yet the evidence presented by pimentel and his associates does not support their argument. in- deed, the data they cite indicate, if anything, that u.s. corn producers are using less than the optimum amount of energy input per unit of corn produc- tion. the energy accounting convention adopted by pimentel et al. involves an implicit assumption that a kilocalorie of energy in the form of corn is equal to a kilocalorie of energy embodied in the itemized input. if society were to adopt the assumption that energy rep- resents an appropriate numeraire (or unit of account) for purposes of public policy and for private production and consumption decisions, the optimum (or equilibrium) level of energy input and of commodity and service output would be defined at the point where an in- cremental kilocalorie of energy input would produce an increment of kcal of output in each line of pro- duction (whether in the form of corn or wheat, grain or meat, food or shelter, commodities or services). the general optimization (or equilibrium) principle -that the value of the marginal or incremental input should be equal to the value of the marginal product- holds, regardless of the accounting con- vention adopted by society in placing values on inputs and outputs. the data presented by pimentel et al. show that energy output (in the form of corn) per unit of energy input de- clined sharply from to , and that it may have declined modestly be- tween and . between and corn output rose by . x kcal while energy input rose by . x kcal. if we think in terms of an s-shaped energy input-output or energy response curve, the and observations are apparently near the inflection point. the optimum level of energy input in u.s. corn production would be the point where a line with a ° slope (the price line consistent with the assumption that kcal of input is equal in value to i kcal of output) is tangent to the energy response curve. at that point an increment of kcal of energy input would add kcal of energy output in the form of corn. thus, even if energy accounting is ac- cepted as an appropriate basis for de- cision-making, the implication of the data presented in the article is that u.s. farmers are using less than the optimum level of energy in corn production. energy does not, however, represent a valid numeraire for calculating the optimum level of energy input and of commodity and service production. optimization implies a social rather than a physical evaluation of the utility of the several input components relative to each other and relative to output. society places a higher value on a kilo- calorie of energy in the form of corn (maize) than in the form of tractor fuel. and it places a higher value on a kilocalorie of energy in the form of human labor than in the form of draw- bar horsepower. indeed, energy in the form of human labor is, in the de- veloped world, valued so highly that it is increasingly employed to perform a control function rather than as a source of direct energy input in most produc- tion processes. both the social accounting and en- ergy accounting approaches still lack precision. the estimates constructed by pimentel probably underestimate ener- gy inputs into corn production. the price weights employed in social ac- counting systems are often distorted by institutional rigidities and constraints. regardless of the precision of the mea- sures that are available, however, the effect of using a social accounting mea- sure that aggregates inputs on the basis of value weights is to tip the input- output price line to the right. this is because, when a social accounting sys- tem is used rather than an energy ac- counting system, (i) the value of inputs rises less rapidly as lower cost energy sources are substituted for higher cost energy sources (tractor fuel for labor), and (ii) a higher value is placed on the calories that are available for human consumption than the calories that are embodied in the inputs used in agricul- tliral production. the optimum input level will therefore be to the right of the point where an input-output price line with a slope is tangent to the energy response curve. the optimum level of energy input will be larger if a social accounting approach is em- ployed than when an energy accounting approach is employed. hayami and ruttan ( ) have shown that most of the inputs associated with mechanization have represented substi- tutes for animal power and labor but have contributed very little to the growth of agricultural output. the growth of output over the last several decades has been accounted for primar- ily by inputs associated with ad- vances in biological and chemical tech- nology rather than mechanical tech- nology. it is useful, therefore, to partition the energy inputs employed in corn production into two components-that used primarily to expand the area cul- tivated per worker or material handled per worker (machinery, gasoline, weed killers, electricity, transportation) and that used primarily to increase output per unit area, or to prevent loss of production or product deterioration (nitrogen, phosphorus, potassium, seed, irrigation, insecticides, drying). the ef- fect is to further weaken the implica- tions of the pimentel article. between and an increase of approxi- mately . x kcal of inputs was used to save kcal of labor. the cost of saving an additional unit of labor has clearly become very expen- sive in terms of energy. on the other hand, an increase of . x ; kcal of yield-increasing in- puts was associated with an increase in corn output of . x kcal. the yield-increasing "green revolution" type inputs remain an extremely attractive use of energy even when energy is used as the unit of account. disagreement with the inferences drawn from the data presented by pimentel et al. does not imply disagree- ment with the perspective that less en- ergy intensive technologies should be sought. if the energy response curve can be shifted to the left it would represent a pure gain in efficiency in corn production regardless of whether an energy or a social accounting con- vention is adopted. the high fertilizer prices that have prevailed in national and world markets since mid- are primarily a result of shortages in plant capacity to pro- science, vol. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ duce fertilizer rather than a reflection of a fundamental shift in energy supply- demand relationships ( ). nevertheless, there remains the question, in times of shortage in plant capacity to produce yield-increasing inputs, of how such inputs should be optimally allocated among farms throughout the world. one effect of the "green revolution" has been to provide indian and philip- pine farmers with more efficient re- sponse curves-similar to those avail- able to farmers in the united states, western europe, and japan. because of restricted access to fertilizer, however, indian farmers are operating further down (to the left) on their input re- sponse curves than farmers in developed countries. there can be little doubt that the optimum allocation of fertilizer dur- ing the present period of stress would result in greater use of fertilizer in india and other poor countries, even at the expense of lower use in the united states and other more developed countries. vernon w. ruttan agricultural development council, inc., fifth avenue, new york references . d. pimentel, l. e. hurd, a. c. bellotti, m. j. forster, i. n. oka, . d. sholes, r. j. whitman, science , ( ). . e. hirst, ibid. , ( ). . j. s. steinhart and c. e. steinhart, ibid., p. . . "pointing the way to more rational use of energy," times (london), january . . y. hayami and v. w. ruttan, agricultural development: an international perspective (johns hopkins press, baltimore, ), pp. - . . g. f. donaldson, "issues relating to the fer- tilizer situation: a seminar report," agricul- tural development council-international bank for reconstruction and development fertilizer seminar, princeton, n.j., to may . may ; revised july ruttan appears to read his own con- clusion into our data and then criticizes the conclusion. in his first paragraph, ruttan states that "the evidence pre- sented by pimentel and his associates does not support their argument" (that u.s. corn production is uneco- nomical). this is not our conclusion but ruttan's conclusion. we clearly stated that in spite of a percent decline in corn kilocalorie yield per fuel kilocalorie from to , the . to ratio was economically profit- able for u.s. corn producers. how- ever, we did question whether this return would be economical for less developed nations. furthermore, pimentel et al. ( ), recognizing the rapid use of valuable environmental resource (fuel), sug- gested that fuel prices might rise five- fold over prices. if fuel prices rose this much, then we explicitly stated that a "return of . kcal of corn per kcal of fuel input may then be un- economical." in his comment, ruttan also ques- tions our ( ) using the "implicit as- sumption that a kilocalorie of energy in the form of corn is equal to a kilo- calorie" of fossil fuel. thermodynami- cally and ecologically (energy account- ing) a kilocalorie of corn is equal to a kilocalorie of fuel. economically a kilocalorie of corn has greater price value than a kilocalorie of fuel, but prices are subject to change. the ap- parent difficulty with ruttan's argu- ment is that he desires to equate the laws of thermodynamics and ecology with those of economics. for example, an estimated x "i kcal of solar energy input plus . x kcal of fossil energy input were required to produce . x kcal of corn grain ( ). hence, by eco- logical energy accounting about kcal of fuel and solar energy were necessary to produce kcal of corn product. by economic accounting, the kcal (fuel and light) have a lower price than a corn kilocalorie; therefore, the value of the product (corn) is greater than the input of energy. hence, the operation is economically profit- able. understanding the relation between ecological and economic principles has several important benefits as suggested by georgescu-roegen ( ) and bould- ing ( ). for example, ecological ac- counting of energy inputs and outputs of an agroecosystem provides greater understanding of the interrelations and mechanisms underlying various crop production alternatives. by using this information and assigning current or projected prices for input fuel kilo- calories and output corn kilocalories, sound economic accounting results. hence, combining ecological and economic information significantly strengthens our overall decision-making processes. i agree with ruttan that fossil fuel will have to be used to increase food production for the world popula- tion of billion humans expected in the coming year and billion expected within the next years. with most of the arable land of the earth already in production, the only means of increas- ing production will be to intensify production on the available arable land using fossil fuel inputs. these inputs should be those that primarily increase food production (that is, fertilizer) and not those agricultural inputs that save labor (that is, heavy machinery). finally, the major thrusts of pi- mental et al.'s article were to emphasize that (i) large quantities of fossil energy are used in u.s. agriculture (using corn model), and "green revolu- tion" agriculture requires similar large inputs of fuel; and (ii) fossil fuel energy is a finite environmental re- source, and as it becomes scarce its price value will significantly increase. if the data of our ecological energy accounting are correct and the eco- nomic assumption is sound, then we should anticipate substantial changes in world agriculture and our way of life as fossil fuel shortages intensify. david pimentel new york state college of agriculture and life sciences, cornell university, ithaca references and notes . d. pimentel, l. e. hurd, a. c. bellotti, m. j. forster, i. n. oka, . d. sholes, r. j. whitman, science , ( ). . n. georgescu-roegen, in growth, limits and the quality of life, w. burch and f. h. bormann, eds. (freeman, san francisco, ). . k. e. boulding, in the control of environ- ment, j. d. roslansky, ed. (north-holland, amsterdam, ), pp. - . november february o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ food production and the energy crisis: a comment vernon w. ruttan and david pimentel doi: . /science. . . 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chemistry ; ( ): - http://www.sciencepublishinggroup.com/j/sjc doi: . /j.sjc. . issn: - (print); issn: - x (online) hydrogen fuel cells pem mahmoud mohsen ali ahmad alsayes, khaled hazem hamed ahmed science department, stem high school for boys, oct city, giza, egypt email address: @stemegypt.edu.eg (m. m. a. a. alsayes), @stemegypt.edu.eg (k. h. h. ahmed) to cite this article: mahmoud mohsen ali ahmad alsayes, khaled hazem hamed ahmed. hydrogen fuel cells pem. science journal of chemistry. vol. , no. , , pp. - . doi: . /j.sjc. . received: may , ; accepted: august , ; published: august , abstract: for centuries the energy crisis has been a curse that made egypt and the world suffer in various ways. energy is the backbone of many aspects of life; yet depending on fossil fuel as the main source of energy has numerous drawbacks like the high price, transportation, unavailability and pollution to the environment. this has led us to assign the design requirement of having a cheap, available rather than green fuel for cars. as a result, our pem hydrogen fuel cells are the solution to the problem after making essential changes in order to increase its efficiency while decreasing the price, through using nickel as a catalyst, instead of platinum. finally, the test plan has assured that it meets the design requirements mentioned before, and unquestionably proved that our pem fuel cells are the right and suitable solution for running vehicles. keywords: pem fuel cell, hydrogen, metal hydrides, electric cars . introduction energy is an essential need for our life. it is the essential part of industry, transportation means and domestic uses which connects it to all other grand challenges. however, the energy production worldwide faces many issues, as about % of its production is from fossil fuel. despite its high efficiency, it has many obstacles such as the increasing in prices, the possibility of running out in the near future, polluting the environment and the growing population demand. these problems have a considerable effect on egypt because egypt depends on fossil fuel in producing electricity, and this causes a shortage of , megawatts ( %) resulting in regular blackouts, especially, in summer. egypt also suffer from gas and oil shortage used in domestic uses and vehicles. as a result, egypt seeks to get energy from alternative resources like: hydro power in the high dam, solar energy stations in the western desert and using gasoline instead of oil in cars. admittedly, each of the previous resources couldn’t stand alone for the highly increasing population, so all of them were needed to complete each other and also have a sustainable future. in our research, we have an objective which is achieving less pollutant rather than cheap car fuel by using the pem hydrogen fuel cells. to reach this goal, we have to achieve some requirements such as being affordable by the public, dependable as the main energy source, and non-polluting to the environment. we modified the fuel cell prototype by using stainless-steel and nickel, instead of platinum, as catalyst which reduced the price significantly. and after testing the prototype, we found that it achieves these requirements and leads directly to make hydrogen “the fuel of the future”. . review of literature fuel cells were first invented in the year by william grove which was called by him ‘the gas battery’. its idea of working was based on reversing the process of water electrolysis where the reaction of oxygen and hydrogen together form water and electricity these principles were demonstrated by humphry davy in . in the s the energy crisis arose and fossil fuel was threatened run out at any time. moreover the awareness of how important was it to protect the environment from pollution increased which consequently increased the researches on alternative fuel resources which included the fuel cells. then in s the researchers developed the production of electricity of the fuel cell until it reached mw. in the s attention was given to fuel cells due to its low cost and high production which lead to the developing of its usage in industrial and other fields specially solid oxide fuel cell (sofc) and proton exchange membrane fuel cell (pemfc) which lead into their mahmoud mohsen ali ahmad alsayes and khaled hazem hamed ahmed: hydrogen fuel cells pem use in vehicles (jonathan mathews, ). different types of fuel cells where made like: proton exchange membrane fuel cell (pem), alkaline fuel cell (afc), phosphoric acid fuel cell (pafc), molten carbonate fuel cell (mcfc), solid oxide fuel cells (sofc), regenerative fuel cells (rfcs), zinc air fuel cells (zafcs), and microbial fuel cells (mfcs), but pem fuel cells where the most suitable one for cars and vehicles because it needed low operating temperatures. consequently they were used by honda in to make the first ever fuel cell car. however fuel cells had a significant problem which is the high price due to the use the expensive metal of platinum as a catalyst to separate the hydrogen atoms from each other as well as the oxygen atoms. so several researches where done to develop alternate catalysts these included the use of cobalt-graphene alloy and the use of nickel doped with manganese dioxide and the use of other metal oxides these researches lead us to use nickel presented in stainless alloy. . other solutions already tried the current national energy supply mix in egypt is: � % from fossil fuel (petroleum products and natural gas) � % from renewable resources (mainly hydro and wind, which is increasing gradually) the electricity generation activity utilizes around % of the fossil fuel and natural gas resources in addition to all the hydro and wind energy resources. the industrial activities in egypt consume around % of the overall all energy available. the average annual increase of energy use has been around % over the last decade. producing electricity: its current solution in egypt is hydropower (the high dam), fossil fuel, and wind power, and its tried solution is using coal which didn’t work because, coal produces more pollution than other fossil fuel and transporting it is very expensive relatively. running vehicles: its current solution in egypt is gasoline and natural gas, and its tried solution is vegetable oil, and coal which didn’t work due to some technical problems in the engines. energy transformation: its current solution in egypt is wires (electricity), and pipes and trucks for fluid fuels and its tried solution is trains for coal which didn’t work because, they cause energy lose so we must work on getting with a special way to transport energy to reduce the lose energy. . design requirements cost: is one of the important design requirement in any project because, now egypt suffers from an economic collapse. we have tried to reduce the cost of the hydrogen fuel cell by two major steps: first, we will use nickel in stead of platinum because, platinum is very expensive than gold it also not available in egypt, while nickel is very cheap, and available in egypt. second, we will use gelatin instead of nafion as pem (proton exchange membrane) because, nafion is very expensive that it costs $ for the area of cm^ , and gelatin membrane is made of potassium chloride, distilled water, and gelatin which are all cheap. this design requirement can be tested by calculating the cost of our pem fuel cell, and compering it with the cost of the typical one. it also can be tested by comparing the cost of kw that our pem fuel cell produce, with the cost of amount of gasoline that produce the same amount of energy, or making a ratio between the cost, and the efficiency of our pem fuel cell to compare it with the typical one. safety: we used the hydrogen sensor to make sure that there is no hydrogen leak to make the fuel cell more safety than before. this design requirement can be tested by programing the arduino with the hydrogen sensor to light a red led if there is a hydrogen leak, and putting the sensor in front of the hydrogen tank in different distances to determine the range of danger, and know the number of sensors that can insurance our car from the hydrogen leak . selection of solution. hydrogen fuel cell is way to solve over cars in gasoline stations, because we decided to create it for cars. as a result we won’t use petroleum for cars again because petroleum makes a lot of problems in egypt with high cost for example: pollution, economic problem, and car exhaust. so we used hydrogen fuel cell for cars to solve all of these problems. cars in egypt make a huge problems and there are no solutions until now for them, so we have searched for new researches in many international universities cites like (brown university cite) to know more about hydrogen fuel cell for cars. some basic information about hydrogen: hydrogen is the simplest element. an atom of hydrogen consists of only one proton and one electron. it's also the most plentiful element in the universe. despite its simplicity and abundance, hydrogen doesn't occur naturally as a gas on the earth - it's always combined with other elements. water, for example, is a combination of hydrogen and oxygen (h o). hydrogen is high in energy, yet an engine that burns pure hydrogen produces almost no pollution. nasa has used liquid hydrogen since the s to propel the space shuttle and other rockets into orbit. how does it work: a fuel cell is a device that generates electricity by a chemical reaction. every fuel cell has two electrodes, one positive and one negative, called, respectively, the anode and cathode. the reactions that produce electricity take place at the electrodes. every fuel cell also has an electrolyte, which carries protons particles from one electrode to the other, and a catalyst, which speeds the reactions at the electrodes. hydrogen is the basic fuel, but fuel cells also require oxygen. one great appeal of fuel cells is that they generate electricity with no pollution, because all of the hydrogen and science journal of chemistry ; ( ): - oxygen used in generating electricity ultimately combine to form a harmless byproduct, namely water. how this solution meets our design requirements: the solution which we chose has many characteristic one of them is reducing the cost. we have used nickel instead of platinum because platinum is very expensive than gold, and it will represent a huge economic problem, if we achieve it in real life. also platinum is not saving in egypt. so we have chosen nickel as a solution for this problem, because it is very cheap, and available in egypt, and for safety we used a hydrogen sensor to know if there is gas leaks (hydrogen) from the hydrogen tank to make the fuel cell more safety than before. . test plan the first design requirements we chose to test was the cost of the prototype to make sure that it’s affordable by the public and that we reduced the price of the watt relative to the typical pem hydrogen fuel cell. another design requirement we tested was the safety of the prototype and this test was conducted to make sure that the prototype of the safety system was well operating. i. cost test plan: tools: multimeter – internet to determine costs of some materials objective: this requirement is to compare the price of our fuel cell and its power to those of the pem fuel cell procedures: ). determine the prices and powers of our fuel cell and pem fuel cell with platinum ). set a ratio between fuel cell price to its power, after that we set another ratio between the price of the pem fuel cell to its power success conditions: if the ratio in our fuel cell is less than the ratio in pem fuel cells then it succeeded; otherwise, our fuel cell didn’t meet the requirement. ii. safety test plan tools: balloon filled with hydrogen – arduino–led – hydrogen sensor – jumpers – ruler. objective: this test plan is to test the safety system in the prototype. procedures: ). pass an amount of hydrogen on the sensor from different distances. ). if the led lights then it detected hydrogen as warning to the passenger. ). graph the results of the effect of different distances on the hydrogen sensor. success conditions: if the led lit in the presence of hydrogen this indicates then the safety system is well operating, otherwise it needs some modifications. . methods we have used special materials that we associated together for forming the hydrogen fuel cell prototype. these materials were ( pieces ( x cm ) from nickel used as a catalyst in the fuel cell, ( gm of gelatin, . gm of potassium chloride, ml di water) used for making the proton exchange membrane (pem), pieces ( x cm ) from rubber are put in the prototype to prevent any hydrogen leakage, arduino uno used to program the hydrogen sensor, hydrogen sensor used in the circuit to detect the presence of hydrogen, nuts with their bolts used to fix pieces together, jumpers used to connect different parts of the circuit together, bread board used as construction base for the sensor and other circuits parts, led used in the circuit to light in the presence of hydrogen, and acrylic plastic sheets ( . x cm ) used to make the cover of the pem fuel cell). after the creation of our prototype we used it in two tests one of them was the cost test plan: tools: multimeter – internet to determine costs of some materials. objective: this requirement is to compare the price of our fuel cell and its power to those of the pem fuel cell procedures: determining the prices and powers of our fuel cell and pem fuel cell with platinum, then setting a ratio between fuel cell price to its power, after that we set another ratio between the price of the pem fuel cell to its power. success conditions: if the ratio in our fuel cell is less than the ratio in pem fuel cells then it succeeded; otherwise, our fuel cell didn’t meet the requirement. the other was the safety test plan: tools: balloon filled with hydrogen – arduino–led – hydrogen sensor – jumpers – ruler. objective: this test plan is to test the safety system in the prototype. procedures: passing an amount of hydrogen on the sensor from different distances, and observing the distance that the led don’t light in, then graphing the results of the effect of different distances on the hydrogen sensor. success conditions: if the led lit in the presence of hydrogen this indicates then the safety system is well operating, otherwise it needs some modifications. . results after doing the coast test plan we founded that the total cost of raw material used in prototype= (price of gelatin + price of stainless steel + price of rubber + price of nuts and bolts + price of potassium chloride + price of distilled water + price of acrylic sheets) = pounds and it produces . (± . ) volts and . (± . ) watts. an average fuel cell made of platinum costs about l.e and produces . (± . ) volts and . ( . ) watts cost to power ratio in our fuel cell = � = ���� ���	 = � 
��� = . l.e/watts cost to power ratio in pem fuel cell (using platinum) = ���� ���	 = �

 
.� = . l.e/watts. when we finished the safety test plan we made sure that our prototype is safe, because it can measure the danger of hydrogen leak until cm (± . cm) far from the hydrogen storage as shown in graph so the distance between each sensor and the other will be cm. mahmoud mohsen ali ahmad alsayes and khaled hazem hamed ahmed: hydrogen fuel cells pem recommendations catalysts: doing further researches on alternative catalysts used in the fuel cell as cobalt-graphene, which provide more efficiency because it has more unpaired electrons on its (d) sup-level which help it to make ponds with reactant. however; it is less expansive than platinum, and carbon nano-tubes which increase the efficiency by %. however; it also more cheaper than platinum. hydrogen storage: using metal hydrides in storage of hydrogen which proved in many researches to have high capacity with lower price made of simple material as aluminum and stainless steel. this hydrides hosepipe is covered with nano ceramic which prevents the hydrogen from leaking. electric loss: searching ways to reduce any electric loss by developing the concept of using super-conductors instead of using cupper, because the super-conductors can reach zero resistance. motors: the use of volts electric dc motors which will be suitable to cars running on fuel cells and have lower price as brushless and induction motors. producing hydrogen: preforming further researches on new environmental ways to produce hydrogen used in fuel cells as conversion of biomass and wastes, solar thermal water splitting. references [ ] problem . 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( , may ). retrieved april , . autophagy, metabolism, and cancer autophagy, metabolism, and cancer jessie yanxiang guo , , and eileen white , rutgers cancer institute of new jersey, new brunswick, new jersey department of medicine, rutgers robert wood johnson medical school, new brunswick, new jersey department of chemical biology, rutgers ernest mario school of pharmacy, piscataway, new jersey department of molecular biology and biochemistry, rutgers university, piscataway, new jersey abstract macroautophagy (autophagy hereafter) is a process that collects cytoplasmic components, particularly mitochondria, and degrades them in lysosomes. in mammalian systems, basal autophagy levels are normally low but are profoundly stimulated by starvation and essential for survival. cancer cells up-regulate autophagy and can be more autophagy-dependent than most normal tissues. genetic deficiency in essential autophagy genes in tumors in many autochthonous mouse models for cancer reduces tumor growth. in k-rasg d-driven non–small cell lung cancer (nsclc) and other models, autophagy sustains metabolism and survival. the mechanism by which autophagy promotes tumorigenesis varies in different contexts, but evidence points to a critical role for autophagy in sustaining metabolism, thereby preventing p activation, energy crisis, growth arrest, apoptosis, senescence, and activation of the immune response. autophagy in nsclc preserves mitochondrial quality and regulates their abundance. by degrading macromolecules in lysosomes, autophagy provides mitochondria with substrates to prevent energy crisis and fatal nucleotide pool depletion in starvation. we review here how autophagy supports mammalian survival and how cancer cells usurp this survival mechanism to maintain mitochondrial metabolism for their own benefit. insights from these studies provide the rationale and approach to target the autophagy survival pathway for cancer therapy. autophagy captures and degrades intracellular proteins and organelles in lysosomes (mizushima and komatsu ). the autophagy pathway was first identified by yeast genetic approaches to confer survival to nitrogen starvation. later it became apparent that newborn mice also require autophagy to survive starvation (kuma et al. ; komatsu et al. ). thus, autophagy is an intracellular nutrient scavenging pathway whereby cells eat this article is distributed under the terms of the creative commons attribution-noncommercial license, which permits reuse and redistribution, except for commercial purposes, provided that the original author and source are credited. correspondence: epwhite@cinj.rutgers.edu. disclosure of potential conflicts of interest e.w. is on the scientific advisory board of forma therapeutics. hhs public access author manuscript cold spring harb symp quant biol. author manuscript; available in pmc july . published in final edited form as: cold spring harb symp quant biol. ; : – . doi: . /sqb. . . . a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t parts of themselves and presumably recycle the breakdown products, to sustain survival in starvation. basal levels of autophagy are normally low but are profoundly induced by stress and starvation, indicating that rapid autophagy mobilization is part of the integrated stress response (mizushima et al. ). genetic ablation of autophagy in various settings causes the accumulation of autophagy substrates, particularly damaged proteins and organelles such as abnormal mitochondria (mizushima and komatsu ). thus, autophagy is needed for metabolic homeostasis and for protein and organelle quality and numerical control. without autophagy, survival to stress is compromised, and cells and tissues are subjected to the toxic effects of vast accumulation of autophagy substrates. because the levels of half the cellular proteins are affected by the functional status of autophagy, this pathway represents a major mechanism for protein turnover and homeostasis (mathewet al. , ). unlike normal cells, tumor cells can have high levels of basal autophagy and can be constitutively dependent on autophagy for survival (degenhardt et al. ; guo et al. ; yang et al. ). autophagy is also induced in hypoxic tumor regions and confers a survival advantage (degenhardt et al. ). these findings suggest that autophagy inhibition may compromise tumor survival and may be a new approach ripe to target for cancer therapy (amaravadi et al. , ). indeed, genetically engineered mouse models (gemms) for cancer where essential autophagy genes are ablated show the functional importance of autophagy for various aspects of tumorigenesis (amaravadi et al. ). autophagy in these gemms for cancer promotes the growth, survival, and malignancy of a broad spectrum of cancers that was reviewed in detail recently (amaravadi et al. ). herein we provide an overview and discuss the settings and underlying mechanisms by which autophagy promotes tumorigenesis. autophagy is required for mammalian survival first insight into the role of autophagy in sustaining mammalian survival came from studies where an essential autophagy gene was deleted in mice. these mice are born but fail to survive the neonatal starvation period (kuma et al. ; komatsu et al. ). feeding autophagy-deficient neonatal mice extends survival only briefly indicating that autophagy is essential for mammalian survival to neonatal starvation but also generally. in contrast, adult mice subjected to conditional whole-body deletion of an essential autophagy gene live for – months, indicating that adult mice are less autophagy-dependent than neonates (karsli- uzunbas et al. ). adult mice are physiologically and metabolically different from neonates and possess dedicated nutrient stores that may reduce autophagy dependence. fasting these adult mice without autophagy, however, is lethal (karsli-uzunbas et al. ). thus, the main function of autophagy conserved from yeast to mammals is to confer survival to starvation. how does autophagy promote survival to starvation at the cellular and organismal level? during fasting, normal adult mice activate autophagy at the cellular level to sustain cell survival and they mobilize nutrient stores at the organismal level to sustain circulating nutrients essential for survival (karsli-uzunbas et al. ). for example, glycogen is guo and white page cold spring harb symp quant biol. author manuscript; available in pmc july . a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t degraded to generate circulating glucose (fig. ). lipid in white adipose tissue (wat) is also degraded to produce glycerol and fatty acids that are used as substrates for ketogenesis and gluconeogenesis in the liver (fig. ). with prolonged starvation, muscle protein is degraded to produce amino acids for use by the liver to synthesize ketone bodies and glucose. this prioritized mobilization of circulating nutrients is aimed at maintaining circulating substrates for brain metabolism, the absence of which is fatal (fig. ). in contrast, adult mice without autophagy owing to conditional deletion of the essential autophagy gene atg have a systemic metabolic defect that is fatal during fasting (karsli- uzunbas et al. ). the inability to activate autophagy at the cellular level causes rapid depletion of glycogen and wat lipid stores, and extensive muscle catabolism (cachexia) (fig. ). the accelerated depletion of nutrient stores causes autophagy-deficient mice to fail to maintain circulating glucose levels, resulting in death within h from hypoglycemia (karsli-uzunbas et al. ). autophagy in the liver appears necessary to sustain circulating glucose levels and brain function (ezaki et al. ; karsli-uzunbas et al. ). thus, autophagy in mammals is essential to supply circulating nutrients for systemic metabolism during fasting. the inability of cells to use autophagy may create a systemic metabolic deficit, accelerating catabolism of nutrient stores (karsli-uzunbas et al. ). alternatively, autophagy may be directly involved in the secretion of essential metabolic substrates into the circulation, the absence of which increases dependency on nutrient stores. these findings also raise the interesting possibility that suppression of autophagy may promote cachexia, a significant medical problem for advanced cancer patients (karsli-uzunbas et al. ). as autophagy is essential for glucose homeostasis in fasted adult mice, is there a role also in the fed state? a small fraction of the adult mice conditionally deleted for atg die soon after deletion from streptococcus infection (karsli-uzunbas et al. ). in in vitro experiments autophagy plays a role in host defense by eliminating intracellular bacteria including streptococcus, and this finding indicates that this may also be relevant in vivo. most adult mice conditionally deleted for atg die – months postdeletion (karsli-uzunbas et al. ). this contrasts neonatal mice that fail to tolerate atg deletion (kuma et al. ; komatsu et al. ). neurodegeneration is the main cause of death of atg conditionally ablated adult mice (karsli-uzunbas et al. ), which is not surprising given that autophagy deficiency targeted to the brain also causes neurodegeneration (hara et al. ; komatsu et al. ). what is surprising is that neurodegeneration upon conditional deletion of atg in the whole body is greatly accelerated in comparison to tissue-specific deletion (karsli-uzunbas et al. ). this suggests that autophagy deficiency in non-neuronal tissues also contributes to neurodegeneration, perhaps through defective systemic metabolism. these atg -ablated adult mice have a deficit in circulating arginine levels, and it will be of great interest to explore if this contributes to the neurodegeneration phenotype (karsli-uzunbas et al. ). another important unanswered question is why tissues like the brain are more autophagy-dependent than other tissues, such as lung. in summary, switching off autophagy in adult mice is tolerated for weeks in the fed state. guo and white page cold spring harb symp quant biol. author manuscript; available in pmc july . a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t autophagy promotes tumorigenesis in gemms for cancer the first clue that autophagy is important for the survival of tumor cells came from the observation that, in stark contrast to normal cells, some cancer cells have high levels of basal autophagy (guo et al. ; yang et al. ). up-regulation of autophagy in cancer cells is caused by direct activation of the transcription factors of the microphthalmia-associated transcription factor (mitf)/tfe family that control autophagy and lysosomal biogenesis or by removal of a repressive phosphorylation on the autophagy initiation machinery (perera et al. ; wong et al. ). moreover, deletion of an essential autophagy gene compromises the survival of those tumor cells in vitro and in tumors in vivo (guo et al. ; yang et al. ). this prompted many laboratories to examine the role of autophagy in gemms for cancer where essential autophagy genes are deleted in tumor cells arising spontaneously in the context of a functional immune system. in most of these models, loss of autophagy reduces tumor growth, survival, and proliferation (amaravadi et al. ). in models of k- ras-driven lung and pancreatic cancer, loss of autophagy limits tumor progression to benign disease, which is attributed in part to amplified activation of p . the requirement for autophagy for tumor growth and survival is also apparent with p deletion. in lung cancer gemms, deletion of atg dramatically alters tumor pathology from carcinomas to that of benign oncocytomas, which are human tumors that massively accumulate defective mitochondria (guo et al. ; strohecker et al. ). as defective mitochondria are a major autophagy substrate, this indicates that benign human tumors manifest a phenotype of defective autophagy, perhaps explaining their benign status. indeed, genomic and biological characterization of human renal oncocytomas revealed a metabolic defect stemming from pathogenic mitochondrial genome mutations and defective intracellular trafficking, lysosome, and autophagy function (joshi et al. ). these benign tumors represent a natural setting where tumor progression is halted due to deficient metabolism, which can be caused by loss of mitochondrial energy homeostasis and quality control. tumors are more autophagydependent than most normal tissues these collective findings suggest that autophagy inhibition may be a therapeutic approach for some cancers (amaravadi et al. ). as autophagy is important for some normal tissues, this raised the question as to whether the selective dependency of tumors on autophagy is sufficient to produce a therapeutic window. to address this, the essential autophagy gene atg was deleted conditionally in the whole body of mice with established k-ras-driven lung cancer. conditional, systemic autophagy loss has remarkable antitumor activity, more so than tumor-specific loss (karsli-uzunbas et al. ). this suggests that host autophagy in addition to tumor cell autonomous autophagy contributes to tumor growth. indeed, stromal cell autophagy in models of pancreatic cancer leads to secretion of alanine that is used by tumor cells as metabolic fuel (sousa et al. ). blockade of this tumor metabolism-promoting metabolic cross talk between stroma and tumor is an additional anticancer benefit of autophagy inhibition (amaravadi et al. ). whether systemic autophagy beyond stroma also contributes to tumor growth remains to be explored. guo and white page cold spring harb symp quant biol. author manuscript; available in pmc july . a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t autophagy recycles macromolecules although the experiments above begin to address the role of autophagy in sustaining whole- body mammalian metabolism, what happens at the cellular level is still an open question. how does autophagy promote survival of cells in starvation? is this through recycling of cellular components? do cancer cells do this differently from normal cells and tissues? to begin to address these points we developed an assay to directly measure autophagy-mediated recycling of macromolecules into cancer cell metabolism to find out whether recycling occurs, and if so, what it is used for. cancer cells derived directly from the tumors arising in the gemms for lung cancer are autophagy dependent as isogenic atg -deficient tumor cells are more sensitive to starvation than atg wild-type tumor cells (guo et al. ; strohecker et al. ). to address why autophagy deficiency causes sensitivity to starvation, individual nutrients were added back to determine which were essential for survival. we found that glutamine supplementation in starvation conditions is most effective at rescuing the survival of autophagy-deficient tumor cells (guo et al. ; strohecker et al. ). because glutamine is a major anapleurotic substrate for the tricarboxylic acid (tca) cycle (zong et al. ), this suggests that autophagy may recycle intracellular macromolecules to provide amino acid substrates such as glutamine to maintain mitochondrial function (fig. ). to test this hypothesis, macromolecules of atg wild-type and deficient tumor cells were stably labeled with heavy isotopes of carbon and nitrogen. the label was then briefly chased out of metabolic pathways with cold media, and then the cells were challenged with starvation to force autophagy-mediated recycling specifically in the atg competent cells and not in the atg - deficient cells. reappearance of heavy isotope labeled metabolites into central carbon metabolism was then assessed by liquid chromatography and mass spectrometry (guo et al. ). upon challenge with starvation, labeled metabolites were enriched in the atg competent compared with deficient tumor cells, particularly in tca cycle intermediates and amino acids synthesized in mitochondria (guo et al. ). what surprised us was that labeling of metabolism was also apparent in the atg -deficient tumor cells, although it was significantly less than atg wild-type cells. this indicates that autophagy does recycle macromolecules in starvation, that this is specific to mitochondrial metabolism, but that there also exists autophagy-independent mechanisms for recycling (guo et al. ). what those autophagy- independent mechanisms of recycling are is not known but proteasome-mediated or other forms of lysosome-mediated degradation may be responsible. autophagy-mediated recycling promotes cancer metabolism if autophagy is degrading macromolecules in starvation to supply substrates for mitochondrial metabolism, what are the substrates used for? isotope tracing helped answer this question. carbon flux from glutamine is accelerated in atg -deficient tumor cells in starvation where it flows from the tca cycle to pyruvate and to aspartate (fig. ). using glutamine carbon to synthesize pyruvate can produce nicotinamide adenine dinucleotide phosphate (nadph) via malic enzyme for use in generating reduced glutathione for guo and white page cold spring harb symp quant biol. author manuscript; available in pmc july . a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t antioxidant defense (guo et al. ). aspartate is a major biosynthetic product of oxaloacetate (oaa) from the tca cycle and is a precursor for de novo nucleotide biosynthesis (guo et al. ). finally, the general supply of substrates to mitochondria through autophagy can drive energy production (guo et al. ). these findings pointed to a role for autophagy-supplied mitochondrial substrates in redox homeostasis, nucleotide biosynthesis, and energy homeostasis (fig. ). atg deficiency increases reactive oxygen species (ros), which is extinguished by glutamine supplementation in starvation (guo et al. ). scavenging ros, however, fails to rescue survival of starved atg -deficient tumor cells. thus, autophagy-supplied substrates function in maintaining redox homeostasis, although restoring redox balance alone is insufficient to rescue survival in starvation. starving atg -deficient tumor cells severely depletes nucleotide pools, particularly adenosine nucleotides, consistent with a requirement for autophagy to supply substrates for aspartate and de novo nucleotide synthesis (guo et al. ). supplementation of autophagy- deficient tumor cells with nucleosides during starvation rescues survival, indicating that autophagy prevents fatal nucleotide pool depletion. in starvation, autophagy also prevents loss of mitochondrial respiration, atp loss and amp accumulation, and amp kinase activation (guo et al. ). thus, a major function of autophagy is to supply substrates for mitochondrial metabolism to maintain energy homeostasis. the depletion of nucleotide pools and energy crisis in starved autophagy-deficient tumor cells may be related. in yeast, autophagy loss also causes amp accumulation and energy crisis in starvation, triggering amp degradation to escape energy crisis in the short term (walther et al. ). in tumor cells, as in yeast, the requirement for autophagy to supply substrates for de novo nucleotide synthesis in starvation may also be caused by energy crisis and amp degradation as a means to escape energy crisis (fig. ). indeed, nucleotide degradation products accumulate to high levels in starved atg -deficient but not atg wild- type tumor cells (guo et al. ). autophagy therefore becomes essential to provide metabolic substrates to prevent energy crisis upon nutrient deprivation and thereby the subsequent nucleotide pool depletion. conclusion from the study of genetically engineered mice, it is clear that autophagy is important for systemic adult mammalian metabolism. during fed conditions, autophagy is less critical, conferring loss of wat, select tissue damage, susceptibility to infection, and neurodegeneration after – months. autophagy is, however, critical to prevent fatal hypoglycemia during fasting. we discovered that autophagy is a component of nutrient sharing among tissues, as rapid depletion of wat and glycogen in mice with conditional loss of atg is also associated with excessive muscle catabolism. the metabolic defect at the cellular level creates a systemic metabolic deficit, accelerating exhaustion of nutrient stores and compensatory destruction of muscle, which is ultimately fatal. guo and white page cold spring harb symp quant biol. author manuscript; available in pmc july . a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t many tumors up-regulate autophagy transcriptionally and posttranscriptionally and depend on it for macromolecular recycling and survival, a requirement that is particularly acute in stress in the tumor microenvironment and during starvation. indeed, the antitumor activity of caloric restriction is enhanced by deficiency in autophagy (lashinger et al. ). in k-ras- driven non–small cell lung cancer, macromolecular recycling by autophagy suppresses oxidative stress, but preventing energy crisis and nucleotide pool depletion are essential for survival to stress. as some tumors are more autophagy-dependent than most normal tissues, it will be important to determine the therapeutic utility of autophagy inhibition in cancer therapy (amaravadi et al. ). acknowledgments j.y.g. is supported by the national institutes of health (nih) award k ca . e.w. is supported by the nih under award numbers r ca , r ca , r ca , and r ca , the robert wood johnson foundation, and p ca to the rutgers cancer institute of new jersey. references amaravadi rk, lippincott-schwartz j, yin xm, weiss wa, takebe n, timmer w, dipaola rs, lotze mt, white e. principles and current strategies for targeting autophagy for cancer treatment. clin cancer res. ; 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[pubmed: ] guo and white page cold spring harb symp quant biol. author manuscript; available in pmc july . a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t figure . mechanism by which autophagy promotes the survival of adult mice during fasting. during fasting, healthy adult mice activate autophagy and degrade glycogen to maintain circulating glucose and mobilize lipid stores to produce glycerol and fatty acids for ketogenesis and gluconeogenesis. as a last resort, muscle degradation by atrophy-associated e ligases may supply amino acids for ketogenesis and gluconeogenesis (karsli-uzunbas et al. ). as a result, glucose homeostasis is maintained by autophagy in mice to surviving fasting. however, fasting adult mice with acute autophagy ablation causes excessive depletion of nutrient stores including lipid and glycogen, accelerated muscle catabolism, and liver damage, which causes severe systemic hypoglycemia, brain damage, and mouse death. (modified, with permission, from karsli-uzunbas et al. , © aacr.) guo and white page cold spring harb symp quant biol. author manuscript; available in pmc july . a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t figure . defective autophagy in tumor cells alters metabolic flux from glutamine to aspartate and to de novo nucleotide synthesis. k-ras-driven tumor cells depend on autophagy to supply the substrate glutamine and its derivatives to sustain mitochondria metabolism for starvation survival. to compensate, atg -deficient tumor cells significantly increase glutamine flux to the tricarboxylic acid (tca) cycle, de novo nucleotide synthesis, and nicotinamide adenine dinucleotide phosphate (nadph) generation by up-regulating flux from malate, pyruvate, acetyl-coa, and citrate for antioxidant defense (guo et al. ). oaa, oxaloacetate; α- kg, α-ketogluturate. guo and white page cold spring harb symp quant biol. author manuscript; available in pmc july . a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t figure . autophagy recycles macromolecules to provide mitochondrial substrates for nucleotide synthesis and energy homeostasis. tumor cells rely on mitochondria metabolism for their proliferation and tumorigenesis. in starvation, autophagy is essential to mediate substrate recycling to supply tricarboxylic acid (tca)-associated amino acids, which are further metabolized through the tca cycle for energy production and de novo nucleotide biosynthesis. oaa, oxaloacetate; etc, electron transport chain. guo and white page cold spring harb symp quant biol. author manuscript; available in pmc july . a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t figure . autophagy-supplied substrates prevent energy crisis and fatal nucleotide depletion. substrates derived from autophagy are required to generate atp via tricarboxylic acid (tca) cycle–driven oxidative phosphorylation in starvation. in the absence of autophagy, defective de novo nucleotide synthesis and increased nucleotide degradation cause nucleotide pool depletion and cell death. guo and white page cold spring harb symp quant biol. author manuscript; available in pmc july . a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t a u th o r m a n u scrip t 	abstract 	autophagy is required for mammalian survival 	autophagy promotes tumorigenesis in gemms for cancer 	tumors are more autophagydependent than most normal tissues 	autophagy recycles macromolecules 	autophagy-mediated recycling promotes cancer metabolism 	conclusion 	references 	figure 	figure 	figure 	figure hbot in tbi velho et al. thieme role of hyperbaric oxygen therapy in traumatic brain injury—evidence-based consensus vernon velho hrushikesh kharosekar laxmikant bhople deepak a. palande department of neurosurgery, sir j j group of hospitals and grant medical college, mumbai, maharashtra, india address for correspondence hrushikesh u. kharosekar, mch, department of neurosurgery, th floor, grant medical college and sir j j group of hospitals, byculla e, mumbai , maharashtra, india (e-mail: hkharosekar@gmail.com). traumatic brain injury (tbi) is a major health problem in india and worldwide, resulting in significant morbidity, mortality, and disabilities of young and productive group of society. various treatment modalities in the immediate period following a tbi are focused on altering the acute pathophysiology. secondary injury is precipitated by ischemia resulting from decreased cerebral blood flow leading to hypoxia and is particularly likely to occur in the first hours after injury. hyperbaric oxygen therapy (hbot) targets tbi-induced ischemia by exposing patients to an environment that substantially increases the amount of o inspiration ( % o at > atmosphere absolute), producing an increased o concentration in the plasma and thus increased delivery of o for diffusion to brain tissue. despite the capacity of hbot to protect against secondary ischemic damage, the use of hbot for the treatment of tbi has been controversial. to gain acceptance in routine clinical use, a clinical method of assessing its effectiveness in the individual patient, computed tomography perfusion scan, single-photon emission computed tomography scans, and other intermediate indicators of the effects of hbot should be examined by large and high-quality studies. abstract keywords ► hyperbaric oxygen therapy ► traumatic brain injury doi https://doi.org/ . /s- - issn - . © neurotrauma society of india introduction traumatic brain injury (tbi) is a major health problem in india and worldwide, resulting in significant morbidity, mortality, and disabilities of young and productive group of society. it has enormous social and economic impacts across a large variety of populations. as most of the patients suffer- ing from tbi are young adults, saving their lives and improv- ing the outcome remain the goal. despite the physical and financial impact on individual and society, there has been little advancement in the acute treatment of tbi in past years, and clinical outcomes have not improved much. various treatment modalities in the immediate period following a tbi are focused on altering the acute patho- physiology. the most common pathological mechanism in primary injury is diffuse shearing of axonal pathways and small blood vessels, also known as diffuse axonal injury. however, following the primary mechanical injury to the brain, secondary injury frequently develops. this secondary injury is precipitated by ischemia resulting from decreased cerebral blood flow (cbf) leading to hypoxia and is par- ticularly likely to occur in the first hours after injury. because of decreased oxygen (o ) delivery to brain cells, the brain converts from aerobic to highly inefficient anaerobic metabolism, resulting in inadequate energy production in the brain and eventual cell death. due to the diffuse nature of injury, affecting multiple brain areas, cognitive impair- ments are usually the predominant symptoms. global brain hypoperfusion, and its related tissue ischemia, detected in patients suffering from tbi, serves as a rate-limiting factor for any regenerative process. - hyperbaric oxygen therapy (hbot) targets tbi-induced ischemia by exposing patients to an environment that sub- stantially increases the amount of o inspiration ( % o at > atmosphere absolute [ata]), producing an increased o concentration in the plasma and thus increased delivery of o for diffusion to brain tissue. by increasing the oxygen level in blood and body tissues, hbot can augment the repair indian j neurotrauma: ; : – review article published online june , published online: - - hbot in tbi velho et al. indian journal of neurotrauma vol. no. / mechanisms. various models have strongly suggested that hbot can induce angiogenesis, improve brain plasticity, enhance neurogenesis and synaptogenesis, and foster functional recovery. despite the capacity of hbot to protect against second- ary ischemic damage, the use of hbot for the treatment of tbi has been controversial. one concern regarding the use of hbot for acute tbi arises from apparent conflicts in the literature regarding its efficacy. it is likely that injury heterogeneity, variable injury chronicity, and variability in study design have contributed to this perception. additional concerns relate to o toxicity and the logistics of widespread implementation of this therapy. , history hbot is defined by undersea & hyperbaric medical society as a treatment in which a patient intermittently breathes % oxygen while the treatment chamber is pressurized to a pressure greater than sea level ( ata). the pressure increase must be systemic, and may be applied in monoplace or multiplace chambers. the history of hyperbaric medicine reaches back to the year when drebbel developed a one-atmosphere diving bell, and years later boyle joined forces with gay-lussac to develop the general gas law. moving the sands of time to the near present day, the modern age of hyperbaric medicine began in , when behnke and shaw used a hyperbaric chamber to treat decompression sickness (dcs). however, it was not until that there was major interest in using hyperbaric oxygenation outside of treating dcs. that year, churchill-davidson began to use oxygen therapy in a hyper- baric chamber to treat the damage induced by radiotherapy in cancer patients. but it was until when rockswold (usa) conducted first double-blind randomized controlled trial showing that hbot reduces mortality in acute tbi by %, the largest single reduction in mortality since the invention of the ambulance. in , us army study confirms harch’s hbot repairs white matter damage in children with cerebral palsy (cp) and a canadian group shows hyperbaric air (the original treatment for dcs and mountain sickness) and hbot . effective in treating cp in double-blind randomized controlled trial. many peer-reviewed articles have been published in the last decade that demonstrate hbot is effective at repairing an injured brain even long after that injury took place. one of the most notable was the article published by harch et al using sessions of -minute treatments at . atmospheric pressure. the blast-induced tbi war veterans experienced a -point iq increase (p < . ), % reduction in postcon- cussion symptoms, % reduction in post-traumatic stress disorder symptoms, and % decrease in depression. this is all consistent with past-published reports of hbot in chronic brain injury. the first battle casualty to be treated with hbot ( . ), was of general patt maney (retired) for his blast-induced brain injury in afghanistan. his treatment was ordered after months of therapy at walter reed had shown minimal improvement. as a result of his injuries, he was non- functional and unable to return to his job. after hbot treat- ment, he was discharged from walter reed and returned to his civilian job as a florida state judge. review of literature pubmed search for clinical studies on use of hbot in tbi was done. there are few clinical studies in literature where hbot was used in tbi. though results in these studies were encour- aging and showed significant improvement in patients, absence of standard test to analyze results was limiting factor. our study a prospective study was conducted in our department of neurosurgery, grant medical college & sir j j group of hospitals, mumbai, india, from august till august . a total of , patients with tbi were analyzed in this study. out of these, , patients with moderate to severe brain injuries were subjected to hbot after stabilization or opera- tive intervention and weaning from ventilator. patients with hemodynamic instability and associated chest injuries were excluded and were included in control group (n = ). among the patient analyzed, more than % were male patients in both groups (►table  ). distribution of type of head injury on computed tomography (ct) scan in both groups is shown in ►table  . our results showed that more than % patients showed rapid improvement in glasgow coma scale (gcs) score as compared with only % in control group (►tables  and  , ►fig.  ). also, there was more than % reduction in hospital stay in study group compared with control group when gcs was more than at admission table demographic distribution sex group hbot group tbi (n = ) control group (n = ) male ( . %) ( . %) female ( . %) ( . %) abbreviations: hbot, hyperbaric oxygen therapy; tbi, traumatic brain injury. table types of traumatic brain injury in both groups type of tbi hbot group (n = ) control group (n = ) extra axial hematoma ( . %) ( %) sdh ± contusion ( . %) ( . %) sah ( . %) ( . %) diffuse axonal injury ( . %) ( . %) pure contusion ( . %) ( . %) abbreviations: hbot, hyperbaric oxygen therapy; sah, subarachnoid hemorrhage; sdh, subdural hematoma; tbi, traumatic brain injury. indian journal of neurotrauma vol. no. / hbot in tbi velho et al. (►table  , ►fig.  ). we have analyzed the results using gcs score, functional outcome, and ct perfusion scan, but still tools for analyzing the benefits of hbot are very limited. discussion mechanism of hbot during the acute phase of a severe tbi, the metabolic demands of the brain increase but o delivery to the brain decreases due to a reduction in cbf as well as barriers to o diffusion are caused by capillary endothelial edema, which is exacerbated by the neuroinflammatory response to trauma, capillary collapse, and increased intracranial pressure (icp). this o deficiency forces a conversion to anaerobic metabolism, leading to the depletion of cellular energy (adenosine triphosphate, atp) and eventually to cell death. the cellular energy crisis resulting from inadequate o delivery results in electrolyte imbalances, stemming from the lack of energy for normal na+/k+ atp-ase pump function within neurons and glial cells. this imbalance leads to an increased calcium influx, resulting in an abnormally elevated release of excitatory neurotransmitters and further disrup- tion of mitochondrial metabolism in a positive feed-forward manner that causes excessive free-radical buildup. as the table gcs score in hbot and control group on admission gcs hbot group (traumatic) (n = ) control group (n = ) – ( . %) ( . %) – ( . %) ( . %) ≤ ( . %) ( . %) abbreviations: gcs, glasgow coma scale; hbot, hyperbaric oxygen therapy. table change in gcs at discharge (after cycles hbot) gcs hbot group (traumatic) (n = ) control group (n = ) + ( . %) ( . %) + ( . %) ( . %) + ( . %) ( . %) ( . %) ( . %) abbreviations: gcs, glasgow coma scale; hbot, hyperbaric oxygen therapy. fig. functional outcome chart. hbot, hyperbaric oxygen therapy. table duration of hospital stay gcs hbot group n = control group n = – – d (mean: . ) – d (mean: . ) – – d (mean: . ) – d (mean: . ) < – d (mean: . ) – d (mean: . ) abbreviations: gcs, glasgow coma scale; hbot, hyperbaric oxygen therapy. fig. histographic presentation of duration of hospital stay. hbot in tbi velho et al. indian journal of neurotrauma vol. no. / neuroinflammatory response continues, apoptosis-mediator proteins such as bcl- and bcl-xl initiate the process of cell death. this biochemical cascade resulting in potentially large-scale cell death demonstrates the need for providing an adequate o supply following tbi to limit secondary ischemic injury. the effects of hbot are mediated by increasing the o dis- solved in plasma, as opposed to the o carried by hemoglobin. for example, the dissolved o content (volume %) at room air ( ata) is . . at . ata, it is increased by a factor of . . when additional o becomes available for diffusion across capillary endothelium, anaerobic metabolism converts back to aerobic metabolism, allowing mitochondria to restore depleted cellular energy. this neuroprotective effect can be objectively observed in the traumatized human brain by improved cerebral metabolic rate of oxygen (cmro ) measurements following hbot treatments, as mitochondrial metabolism accounts for > % of o consumption in the brain. this neuroprotec- tive increase in cmro leads to several physiologic benefits. first, returning to aerobic metabolism results in improved energy production and halts the cascade toward cell death described above. second, the averted energy crisis allows for a return of normal autoregulation, which can normalize cbf and icp. third, it decreases the neuroinflammatory response that leads to apoptosis. fourth, as atp becomes available from restored mitochondrial function, the function of na+/k+ atp-ase pumps improves, allowing osmotic effects to alleviate endothe- lial swelling and edema. in turn, this reverse induced barriers to the diffusion of o to the mitochondria. finally, the blood– brain barrier stabilizes and there are increases in stem cell production. hbot has also been proposed as a treatment for the chronic sequelae of tbi, but evidence to support hbot for this purpose is weak. previous review articles have suggested that issues with methodology and statistical analysis may be underlying reasons, but the biochemical mechanism respon- sible for the benefits of hbot in chronic mild tbi is not well documented in either clinical or preclinical work. , controversy surrounding the use of hbot the biochemical mechanisms and physiologic benefits of acutely administered hbot for severe tbi provide objective evidence supporting the use of this treatment in the clinical setting. however, controversy still exists due to safety con- cerns of an increased o dose, how meaningful the benefits in functional outcome are, the feasibility of implementing these treatments, and the apparent inability to consistently replicate data. safety one safety concern related to the therapeutic use of hbot in tbi stems from o toxicity, which is caused by oxidative stress and the formation of reactive o species in the lungs and brain tissue after prolonged exposure to o . oxygen toxicity is com- monly measured in increments of unit pulmonary toxicity dose (uptd). a treatment consisting of minutes of hbot at . ata with compression/decompression at feet/minute generates uptd. at a pressure of . ata, using the same procedure, the o dose is uptd. both paradigms are well below the accepted upper limit. it is important to note that interruptions in o exposure between treatments have been shown to increase o tolerance and improve safety; for example, uptd per day in two treatment sessions was administered for weeks without any evidence of accumula- tive pulmonary toxicity. feasibility questions have been raised regarding the feasibility of hbot, because its use requires hospitals to purchase cham- bers. however, a higher-cost, multiple-occupancy, large compartment chamber requiring sophisticated operation is not necessary for most hospitals. a lower-cost monoplace chamber, which allows for the treatment of a single patient with external support, is entirely adequate and can be incorporated into a critical care area. given the widespread demographic that tbi affects, the widescale implementation of an effective treatment option for these severely injured patients should be seen as an investment rather than a cost. mixed results a major concern of implementing hbot as a clinical treat- ment arises from the perception that the data are not con- sistently replicated in the literature; main factors may contribute to these inconsistencies. the first factor is the heterogeneous pathophysiology of tbi. hbot may not be the best choice for all patients who present with a severe tbi. , conclusion this systematic and comprehensive literature review demonstrates that, despite the controversy surrounding hbot for the treatment of tbi, this therapy has signifi- cant clinical potential. to gain acceptance in routine clin- ical use, a clinical method of assessing its effectiveness in the individual patient, ct perfusion scan, single-photon emission computed tomography scans, and other intermedi- ate indicators of the effects of hbot should be examined by large and high-quality studies. a longitudinal cohort study in which all patients undergo proper diagnostic evaluation as well as standardized follow-up tests is necessary. conflict of interest none. references hadanny a, abbott s, suzin g, bechor y, efrati s. effect of hyperbaric oxygen therapy on chronic neurocognitive deficits of post-traumatic brain injury patients: retro- spective analysis. bmj open ; ( ):e . / bmjopen- – stoller kp. . all the right moves: the need for the timely use of hyperbaric oxygen therapy for treating tbi/cte/ptsd all the right moves: the need for the timely use of hyperbaric oxygen therapy for treating tbi/cte/ptsd. med gas res ; : . /s - - - hu q, manaenko a, xu t, guo z, tang j, zhang jh. hyperbaric oxygen therapy for traumatic brain injury: bench-to-bedside. med gas res ; ( ): – attr_ _ _ .pdf volume • number • september journal of athletic training ; ( ): – � by the national athletic trainers’ association, inc www.journalofathletictraining.org the neurometabolic cascade of concussion christopher c. giza; david a. hovda neurotrauma laboratory, division of neurosurgery, university of california, los angeles school of medicine, los angeles, ca christopher c. giza, md, contributed to conception and design; acquisition and analysis and interpretation of the data; and drafting, critical revision, and final approval of the article. david a. hovda, phd, contributed to acquisition and analysis and interpretation of the data and critical revision and final approval of the article. address correspondence to christopher c. giza, md, division of neurosurgery, mail code , room - npi, university of california, los angeles school of medicine, le conte avenue, los angeles, ca - . address e- mail to cgiza@mednet.ucla.edu. objective: to review the underlying pathophysiologic pro- cesses of concussive brain injury and relate these neurometa- bolic changes to clinical sports-related issues such as injury to the developing brain, overuse injury, and repeated concussion. data sources: over articles from both basic science and clinical medical literature selected for relevance to concussive brain injury, postinjury pathophysiology, and recovery of func- tion. data synthesis: the primary elements of the pathophysio- logic cascade following concussive brain injury include abrupt neuronal depolarization, release of excitatory neurotransmitters, ionic shifts, changes in glucose metabolism, altered cerebral blood flow, and impaired axonal function. these alterations can be correlated with periods of postconcussion vulnerability and with neurobehavioral abnormalities. while the time course of these changes is well understood in experimental animal mod- els, it is only beginning to be characterized following human concussion. conclusions/recommendations: following concussion, cerebral pathophysiology can be adversely affected for days in animals and weeks in humans. significant changes in cerebral glucose metabolism can exist even in head-injured patients with normal glasgow coma scores, underscoring the need for in- depth clinical assessment in an effort to uncover neurocognitive correlates of altered cerebral physiology. improved guidelines for clinical management of concussion may be formulated as the functional significance and duration of these postinjury neu- rometabolic derangements are better delineated. key words: metabolism, physiology, repeated concussion, traumatic brain injury concussion is defined as any transient neurologic dys-function resulting from a biomechanical force. loss ofconsciousness is a clinical hallmark of concussion but is not required to make the diagnosis. other symptoms include confusion, disorientation, unsteadiness, dizziness, headache, and visual disturbances. these postconcussive deficits occur with minimal detectable anatomic pathology and often resolve completely over time, suggesting that they are based on tem- porary neuronal dysfunction rather than cell death. neuronal dysfunction can occur due to ionic shifts, altered metabolism, impaired connectivity, or changes in neurotransmission. thus, a complete understanding of the phenomenon of concussion requires knowledge of the underlying pathophysiology of this injury. in this article, we will review the neurometabolic events following experimental concussive brain injury and then apply this knowledge to specific scenarios pertinent to sport-related concussion. postconcussive pathophysiology an overview of concussion pathophysiology immediately after biomechanical injury to the brain, abrupt, indiscriminant release of neurotransmitters and unchecked ion- ic fluxes occur. the binding of excitatory transmitters, such as glutamate, to the n-methyl-d-aspartate (nmda) receptor leads to further neuronal depolarization with efflux of potas- sium and influx of calcium. these ionic shifts lead to acute and subacute changes in cellular physiology. acutely, in an effort to restore the neuronal membrane po- tential, the sodium-potassium (na�-k�) pump works overtime. the na�-k� pump requires increasing amounts of adenosine triphosphate (atp), triggering a dramatic jump in glucose me- tabolism. this ‘‘hypermetabolism’’ occurs in the setting of di- minished cerebral blood flow, and the disparity between glu- cose supply and demand triggers a cellular energy crisis. the resulting energy crisis is a likely mechanism for postconcus- sive vulnerability, making the brain less able to respond ade- quately to a second injury and potentially leading to longer- lasting deficits. following the initial period of accelerated glucose utiliza- tion, the concussed brain goes into a period of depressed me- tabolism. persistent increases in calcium may impair mito- chondrial oxidative metabolism and worsen the energy crisis. unchecked calcium accumulation can also directly activate pathways leading to cell death. intra-axonal calcium flux has been shown to disrupt neurofilaments and microtubules, im- pairing posttraumatic neural connectivity. this overview represents a simplified framework of the neu- rometabolic cascade (figure ). other important components of posttraumatic cerebral pathophysiology include, but are not limited to, generation of lactic acid, decreased intracellular magnesium, free radical production, inflammatory responses, and altered neurotransmission. we will now discuss some of journal of athletic training figure . neurometabolic cascade following experimental concus- sion. k�, potassium; ca �, calcium; cmrgluc, oxidative glucose metabolism; cbf, cerebral blood flow. (reprinted with permission. giza cc, hovda da. ionic and metabolic consequences of concus- sion. in: cantu rc, cantu ri. neurologic athletic and spine injuries. st louis, mo: wb saunders co; : – .). the pertinent details of postconcussive pathophysiology in both experimental animal models and in humans. acute metabolic and ionic changes immediately after biomechanical injury to the brain, there is disruption of neuronal membranes, axonal stretching, and opening of voltage-dependent k� channels, which leads to a marked increase in extracellular k�. – in addition, nonspe- cific depolarization leads to an early, indiscriminate release of the excitatory amino acid (eaa) glutamate, which exacerbates the k� flux by activating kainate, nmda, and d-amino- - hydroxy- -methyl- -isoxazole-propionic acid (ampa) recep- tors (figure , events and ). in rats, treatment with the eaa inhibitor kynurenic acid greatly diminishes the posttraumatic k� efflux. normally, excessive extracellular k� is taken up by sur- rounding glial cells. – by this mechanism, the brain can main- tain physiologic k� levels after mild perturbations; however, larger insults, such as brain trauma or ischemia, overcome this compensation. – as extracellular k� increases, neuronal de- polarization is triggered, leading to further release of eaas, opening of eaa receptor channels (nmda, ampa, kainate), and still greater k� flux (figure , event ). this massive excitation is then followed by a wave of relative neuronal sup- pression that has been termed spreading depression. – one important distinction between classic spreading depressionand postconcussive k� fluxes is that after trauma, diffuse areas of the brain are affected simultaneously. early loss of conscious- ness, amnesia, or other cognitive dysfunction may be mani- festations of a posttraumatic spreading depression–like state. in an effort to restore ionic homeostasis, energy-requiring membrane pumps are activated – and trigger an increase in glucose use (figure , events and ). – this increase in glucose use occurs almost immediately after fluid percussion injury in rats and persists for up to minutes in the ipsilateral cortex and hippocampus. after more severe injury such as cortical contusion, increased glucose metabolism may last hours in areas distant from the contusion core. because ce- rebral oxidative metabolism typically runs near its maximum, an abrupt increase in energy requirements is best met by an increase in glycolysis. , accelerated glycolysis leads to increased lactate production and is seen after both ischemic – and concussive – brain injury. in addition to hyperglycolysis, oxidative metabolism is also impaired after brain trauma. – this impairment of mi- tochondrial function can lead to reduced atp production, which provides a second stimulus for increased glycolysis. thus, lactate production by glycolysis increases concurrent with a decrease in lactate metabolism, resulting in lactate ac- cumulation (figure , event ). elevated lactate levels can re- sult in neuronal dysfunction by inducing acidosis, membrane damage, altered blood brain barrier permeability, and cerebral edema. – increased levels of lactate after traumatic brain injury (tbi) may leave neurons more vulnerable to a second- ary ischemic injury, but whether this is the case in repeated traumatic injury is not known. an intriguing hypothesis sug- gests that glial lactate production increases posttraumatically and that this excess lactate is actually transported into neurons for use as an alternate fuel. cerebral blood flow–glucose metabolism uncoupling under normal conditions, cerebral blood flow (cbf) is tightly coupled to neuronal activity and cerebral glucose me- tabolism. after experimental fluid percussion injury, however, cbf may be reduced to % of normal. – this posttrau- matic decrease in cbf does not approach the % reduction seen in frank ischemia ; nonetheless, in a setting of increased glucose use (hyperglycolysis), this mismatch in supply and demand results in a potentially damaging energy crisis. calcium influx, mitochondrial dysfunction, and delayed glucose hypometabolism calcium accumulation is seen within hours of experimental concussion and may persist for to days. – the posttrau- matic depolarization and k� efflux triggers the release of eaas that, in turn, activates nmda receptors. activated nmda receptors form a pore through which calcium (ca �) can enter the cell. a potent n-type calcium channel blocker, snx- , significantly reduces postconcussive ca � accu- mulation, presumably by reducing release of glutamate. results of treatment with nmda receptor antagonists have been mixed, however. no reduction in ca � accumulation was seen after weight-drop injury and pre-treatment with the nmda receptor blocker mk- , but treatment with hu- , a synthetic cannabinoid with a pharmacologic profile characteristic of an nmda receptor antagonist, was associated with a reduction in post-tbi ca � accumulation. excess intracellular ca � may also be sequestered in mi- tochondria, , resulting in impaired oxidative metabolism and, ultimately, energy failure (figure , events and ). cytochrome oxidase histochemistry, which is a measure of oxidative metabolism, shows a biphasic reduction after ex- perimental concussion. in the ipsilateral cortex, a relative re- duction on day recovers by day , only to be reinstated on day , to bottom out on day , and to recover by days postinjury. smaller but more lasting changes are seen in the ipsilateral hippocampus, with decreases still evident at days. after the initial period of hyperglycolysis, cerebral glucose volume • number • september figure . neurometabolic cascade following traumatic injury. ( ) nonspecific depolarization and initiation of actionpotentials. ( )release of excitatory neurotransmitters (eaas). ( ) massive efflux of potassium. ( ) increased activity of membrane ionic pumps to restore homeostasis. ( ) hyperglycolysis to generate more adenosine triphosphate (atp). ( ) lactate accumulation. ( ) calcium influx and sequestration in mitochondria leading to impaired oxidative metabolism. ( ) decreased energy (atp) production. ( ) calpain activation and initiation of apoptosis. a, axolemmal disruption and calcium influx. b, neurofilament compaction via phosphorylation or sidearm cleavage. c, microtubule disassembly and accumulation of axonally transported organelles. d, axonal swelling and eventual axotomy. k�, potassium; na�, sodium; glut, glutamate; mg �, magnesium; ca �, calcium; nmda, n-methyl-d-aspartate;ampa,d-amino- -hydroxy- -methyl- -isoxazole-propionic acid. use is diminished by hours postinjury and remains low for to days in experimental animals. positron emission to- mography (pet) in humans shows similar decreases in global cerebral glucose metabolism that may last – weeks post- tbi. in addition, this study found that post-injury hypome- tabolism did not correlate closely with level of consciousness as measured by glasgow coma score (gcs). depressed ce- rebral glucose metabolism was seen in comatose patients as well as in walking, talking patients, suggesting that significant neurometabolic abnormalities may occur in the absence of overt clinical symptoms. what is not yet clear is whether this hypometabolism represents a period when the brain is rel- atively protected from secondary injury or if the brain is more vulnerable because it is unable to respond adequately to further energy demands. it is also unknown whether this depressed glucose metabolism is responsible for more subtle neurocog- nitive deficits seen after tbi. reductions in magnesium intracellular magnesium levels are also immediately reduced after tbi and remain low for up to days. – this reduction in magnesium has been correlated with postinjury neurologic deficits, and pretreatment to restore magnesium levels results in improved motor performance in experimental animals. decreased magnesium levels may lead to neuronal dysfunction journal of athletic training via multiple mechanisms. both glycolytic and oxidative gen- eration of atp are impaired when magnesium levels are low. magnesium is necessary for maintaining the cellular mem- brane potential and initiating protein synthesis. finally, low levels of magnesium may effectively unblock the nmda re- ceptor channel more easily, leading to greater influx of ca � and its potentially deleterious intracellular consequences. diffuse axonal injury mechanical stretching of axons may result in membrane dis- ruption and even depolarization. increased axolemmal per- meability persists for up to hours postinjury , and can lead to influx of ca � (figure , event a) and mitochondrial swelling. , neurofilament compaction occurs from min- utes to hours postinjury (figure , event b), either by phos- phorylation, which alters neurofilament stability, – or by calpain-mediated proteolysis of sidearms, which can lead to neurofilament collapse. increased axonal ca � levels have been shown to lead to microtubule breakdown from to hours after the initial injury (figure , event c). , intra-axonal cytoskeletal abnormalities lead to accumulation of organelles at the site of axonal damage due to continued axonal transport along intact segments. these focal axonal swellings eventually develop constrictions that then lead to secondary axotomy (figure , event d) and formation of ax- onal bulbs. , signs of secondary axonal disconnection may be seen as soon as hours postinjury but have been reported to persist over days and even weeks in brain-injured humans. delayed cell death and persistent calcium accumulation post-tbi increases in ca � do not inevitably lead to cell death. as mentioned previously, elevated intracellular ca � may certainly lead to impaired mitochondrial metabolism, but neurons may still survive. in fact, after moderate experimental concussion, ca � accumulation peaks in days and resolves without obvious morphologic damage by days. animals experiencing more severe injury and demonstrating anatomic damage show persistent ca � elevations at the injury site. in adult animals, a delayed rise ( days postinjury) of ca � is seen in distant structures (thalamus), which corresponds to neuronal death. intracellular ca � may trigger cell death by a variety of mechanisms (figure , event ), including overactivation of phospholipases, plasmalogenase, calpains, , protein kinas- es, nitric oxide synthase, and endonucleases. these alter- ations may then lead to free radical overproduction, cyto- skeletal reorganization, and activation of apoptotic genetic signals. neurotransmitter alterations long-term deficits in memory and cognition in a setting of minimal anatomic change are often seen after concussion. these may result from dysfunctional excitatory neurotrans- mission. postconcussive alterations have been reported in glu- tamatergic (nmda), – adrenergic, , and cholinergic systems. long-term potentiation, an nmda-dependent mea- sure of plasticity, may be persistently impaired in the hippo- campus after concussive brain injury. – concussive brain injury also leads to early changes in choline acetyltransferase activity and later loss of forebrain cholinergic neurons. im- paired cholinergic neurotransmission leads to learning and spa- tial memory deficits in animals. , inhibitory neurotransmission is also altered after tbi. a loss of �-aminobutyric acid-producing (gabaergic) hilarneu- rons can compromise normal inhibition of hippocampal den- tate granule cells. this loss of inhibitory neurons may pre- dispose the traumatized brain to subsequent development of seizures. concerns relevant to athletic concussion concussion in the developing brain with increasing numbers of children and young adults par- ticipating in organized sports and sustaining head injuries, un- derstanding the effects of tbi on the immature brain becomes more and more important. clinical dogma has held that the younger the brain, the more resilient it is after injury. recent studies of moderate fluid percussion in juvenile rats would seem to support this contention, demonstrating no obvious neurologic or pathologic deficits in these young animals. , using a closed head injury weight-drop model, significant def- icits are seen only at injury severities that result in very high mortality ( %). on the other hand, there is also evidence to support the idea of specific developmental periods when the young brain may be more vulnerable to injury. tbi in children results in higher mortality than in adolescents, perhaps due to an increased in- cidence of cerebral edema. – in the experimental model of developmental concussion, the youngest rats became hy- potensive after even mild injuries and tended to have longer apnea times than adult rats. after severe fluid percussion in- jury, mortality in these immature animals approached %. it is reasonable to hypothesize that diffuse mechanical in- jury can have lasting effects on the complex sequence of neu- rochemical and anatomical events occurring during normal de- velopment. indeed, long-term follow-up studies demonstrate persistent neurocognitive deficits after pediatric tbi. , however, it is also difficult to assess developmental deficits in children after mild brain injury, as signs of overt neurologic dysfunction may be lacking, and loss of developmental poten- tial may only be demonstrable at a later time or under specific circumstances. environmental enrichment provides a useful experimental model with which to study developmental plasticity after brain injury. in an enriched environment, rats are reared commu- nally in a large cage with multiple toys, tunnels, and objects that are changed regularly. when compared with animals reared in standard conditions, enriched rats have increases in cortical thickness, larger neurons, more glia, a greater number of synapses, and enhanced dendritic branching. – the en- riched rats are also superior in cognitive testing using the mor- ris water maze. however, when moderately concussed ju- venile rats are reared in an enriched environment, they fail to develop the increased cortical thickness and enhanced cogni- tive performance seen in sham-injured enriched controls. these results demonstrate that developmental brain injury, even without early behavioral deficits or significant later mor- phologic damage, can lead to impaired plasticity. further stud- ies must be done to determine whether this loss of experience- dependent plasticity is permanent or whether it represents a volume • number • september window of impairment after which the capacity for neural re- organization recovers. overuse injury as demonstrated by the recent focus on concussion in foot- ball and hockey, both athletic trainers and athletes feel signif- icant pressure to return athletes to practice and play as soon as possible after injury. although returning to play may be delayed because of concerns about susceptibility to a second brain injury, returning to practice might seem like a reasonable means of maintaining physical conditioning while awaiting full recovery. in animals, the importance of limb use in recovery of func- tion after unilateral cortical lesions has been well demonstrat- ed. in fact, recovery of function was associated with in- creased dendritic growth in the homotopic region of the uninjured cortex, dependent on use of the intact forelimb. however, restraint of the uninjured forelimb, and thus forced overuse of the injured limb, resulted in a failure of dendritic enhancement in the intact cortex, an increase in the lesion size in the injured cortex, and a longer-lasting behavioral deficit. there also appears to be a time window when the deleterious effects of forced overuse are mitigated to some degree. in the same model, when immobilization of the intact arm was de- layed week after the injury, the functional recovery was still delayed, but the increase in lesion size did not occur. the results of these studies suggest that, at least after focal brain injury, it is possible to overstimulate the injured brain and that this excessive activation can lead to longer-lasting deficits. repeated concussion how soon to return to play after a head injury and the con- sequences of repeated concussions are two of the most im- portant health-related issues in sports today. we have earlier reviewed what is known about the neurometabolic cascade of events that occurs after experimental brain injury (figure ). acute abnormalities include ionic fluxes, indiscriminate glu- tamate release, hyperglycolysis, lactate accumulation, and ax- onal injury. later steps in this physiologic cascade involve increased intracellular calcium, mitochondrial dysfunction, im- paired oxidative metabolism, decreased glycolysis, diminished cbf, axonal disconnection, neurotransmitter disturbances, and delayed cell death. it is during this postinjury period, when cellular metabolism is already stretched to its limits, that the cell is more vulnerable to further insults. examining the time course of the post-tbi neurometabolic cascade may help us determine guidelines for vulnerability of the concussed brain to a second injury. several physiologic parameters indicate windows of poten- tial vulnerability in the traumatized brain. first, consider the period of glucose metabolism-cbf uncoupling. this phenom- enon is most dramatic during the hyperglycolytic phase, which, in the rat, begins at the time of injury and lasts for at least minutes. at this time, cerebral metabolism is already at its limit, and any further demand in energy (due to increased ionic flux) or reduction in energy (due to impaired blood flow or reduced atp synthesis) may tip the scale in favor of irre- versible neuronal injury. thus, injured cells may be capable of recovering after an initial injury, but a second concussion during this energy crisis can lead to cell death. after the initial hyperglycolytic period, cerebral glucose metabolism is re- duced, as is cbf, apparently resolving the mismatch in energy supply and demand. however, during this period, cbf may be unable to respond to a stimulus-induced increase in cerebral glucose metabolism, reinstating the metabolic crisis. an in- crease in glycolysis in this period may be due to excessive external stimulation or a second injury (concussion, ischemia, or seizure). a second potential period of vulnerability centers on intra- cellular ca � accumulation. increased ca � levels may impair mitochondrial metabolism at the time when the cell can least tolerate a reduction in atp production. additional ca � influx, again due to increased physiologic stimulation or a second injury, may go on to activate proteases that initiate the march to programmed cell death. in the rat model, this period of acute ca � accumulation is somewhat severity dependent and lasts to days. , another period of risk may be associated with impairedneu- rotransmission. alterations in nmda receptor composition can persist for up to week after injury in developing rats, and a second injury in this period can lead to further impair- ment of excitatory neurotransmission with a greater degree of cognitive dysfunction. long-term potentiation, postulated as a mechanism for learning and memory, is impaired for up to weeks after experimental brain injury and may be another means by which altered excitatory neurotransmission results in neurobehavioral deficits. diminished attention andcognition are particularly important in an athletic setting, when subtle impairments will likely increase the risk of recurrent head in- jury. post-tbi changes in inhibitory neurotransmission seen in rats , can leave neurons more susceptible to massive de- polarization and eaa release after a recurrent concussion. ex- cessive excitation may then more easily lead to seizure activ- ity, increased energy demand, and possibly further cell death. as each of these physiologic parameters has its own time frame, and each head injury can be very different from the next, it is difficult to definitively state the true duration of vulnerability to a second injury. preliminary studies using a double concussion model in rats revealed increased anatomic damage and prolonged hypometabolism when concussions were separated by as much as hours. double concussion also appears to increase immunostaining for glial fibrillary acidic protein (a marker for gliosis and scarring) and lead to greater cell loss when compared with a single injury. inter- estingly, in a recent report, multiple mild concussions preced- ing a more severe concussion by to days actually resulted in a better functional outcome than an isolated severe concus- sion. however, the anatomic injury appeared unchanged. this finding raises the possibility that after tbi, there is a period of increased danger to a second injury, followed by a period when the brain may actually be more capable of re- covering from a repeated injury. of course, translating these experimental time frames into time frames relevant to human concussion can be tricky. post- traumatic derangements in glucose metabolism resolve within to days in rats, whereas in humans, persistent depression of glucose uptake has been reported to weeks later. ev- idence of secondary axotomy is seen as soon as hours post- injury in animals, but evidence of ongoing axonal damage has been reported in human brain tissue even weeks after trauma. in general, the time frame for events in rats is much shorter than for similar periods in humans, and it would not be un- reasonable to assume that these periods of postinjury physio- journal of athletic training logic change are longer lasting in humans. in addition, differ- ences in injury type and severity certainly affect the duration of these neurometabolic changes and must also be considered when determining back-to-play status. summary cerebral concussion is followed by a complex cascade of ionic, metabolic, and physiologic events. the earliest changes are an indiscriminate release of eaas and a massive efflux of k�, triggering a brief period of hyperglycolysis. this is fol- lowed by more persistent ca � influx, mitochondrial dysfunc- tion with decreased oxidative metabolism, diminished cerebral glucose metabolism, reduced cbf, and axonal injury. late events in the cascade include recovery of glucose metabolism and cbf, delayed cell death, chronic alterations in neurotrans- mission, and axonal disconnection. clinical signs and symp- toms of impaired coordination, attention, memory, and cog- nition are manifestations of underlying neuronal dysfunction, most likely due to some of the processes described above. it is difficult to match clinical signs with specific underlying physiologic derangements, and guidelines permiting return to play only after resolution of all motor and cognitive deficits are a minimal precaution. there is recent evidence that even relatively asymptomatic (gcs - ) patients may demon- strate depressed glucose metabolism on pet imaging follow- ing tbi, reinforcing the need for meticulous clinical assess- ment. further study will reveal more details of the time course for this neurometabolic cascade. this will eventually permit improved clinical monitoring of posttraumatic pathophysiolo- gy in actual patients, including variables such as cerebral glu- cose metabolism, blood flow, neuronal activity, and even mo- lecular changes. traumatic injury to the developing brain may lead to long- lasting changes in cognitive potential, perhaps even with little evidence of an initial deficit. children and adolescents who sustain a concussive brain injury should be closely monitored over time for the later appearance of neurobehavioral abnor- malities. repeated injury within a particular time frame can lead to a much larger anatomical or behavioral impairment than iso- lated injuries. the second injury may be obvious, such as a repeated concussion, hypoxia, or seizure, or it may occur in the form of premature activation or overstimulation of the in- jured brain. an awareness and understanding of postconcus- sive pathophysiology will help in 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of the effects of a second insult [abstract]. j neurotrauma. ; : . . allen gv, gerami d, esser mj. conditioning effects of repetitive mild neurotrauma on motor function in an animal model of focal brain injury. neuroscience. ; : – . comprehensive review and future perspectives on the photocatalytic hydrogen production review received: march revised: june accepted article published: june published online in wiley online library: july (wileyonlinelibrary.com) doi . /jctb. comprehensive review and future perspectives on the photocatalytic hydrogen production juan corredor,a maría j rivero,a carmen m rangel,b frederic gloaguenc and inmaculada ortiza* abstract hydrogen represents a renewable energy alternative that may positively contribute to get over the global energy crisis while at the same time reducing its environmental burden. overcoming the challenge of reaching this potential could be helped by careful choice of hydrogen (h ) sources. photocatalytic generation of h , although a minor alternative, appears to be a very good option at the time that liquid wastes are being degraded; therefore, this approach has given rise to an increasing number of interesting studies. here, we aim to provide an integrated overview of the different photocatalytic, heterogeneous, homogeneous and hybrid systems. first, we categorize the units and mechanisms that take part in the photocatalytic process, and secondly we analyze their role and draw comparative conclusions. thus, we analyze the role of (i) the electron source to carry out proton reduction, (ii) the proton source, which can be free protons in the medium or a proton donor compound, (iii) the catalyst nature and concentration, and (iv) the photosensitizer nature and concentration. we also provide an analysis of the influence of the solvent, especially in homogenous systems as well as the influence of ph. we provide a comparison of the photocatalytic performance, highlighting the advantages and disadvantages, of different systems. thus, this review is, on the one hand, an update on the state of the art of photocatalytic generation of h from a full perspective that integrates homogeneous, heterogeneous and hybrid systems, and, on the other, a source of useful information for future research. © society of chemical industry keywords: photocatalytic hydrogen production; homogeneous, heterogeneous and hybrid systems; comparative performance state of the art of photocatalytic generation of hydrogen increased emissions of greenhouse gases to the atmosphere due to fossil fuel combustion pose a serious threat to the environment. hydrogen (h )-based energy comes out as a clean alternative because its direct combustion does not generate pollutants or greenhouse gases. – nowadays, % of h is obtained by steam reforming of fossil fuels, mainly methane. this process operates at high temperatures and pressures, and thus is energy-intensive. – water (h o) electrolysis is one of the most promising h produc- tion alternatives, especially, for storage of surplus electricity; a variety of commercial electrolysers for large-scale applications is available on the market. , however, the energy consumption associated with electrolysis must be significantly reduced before this process becomes competitive at large scales. photocatalytic generation of h from organic solutions or h o, although con- sidered a minor source in terms of produced h volume, appears to be a complementary and renewable way for simultaneous h generation and wastewater remediation. – in , fujishima and honda reported the first heterogeneous photocatalytic h production, hetphp, by water splitting. , het- phps are assisted by a semiconductor that acts as catalyst and light harvester. five years later, lehn et al. ( ) published the first homogeneous photocatalytic h production, homphp, from triethanolamine (teoa). typical homphps involve the use of an organometallic complex as catalyst and a second organic or organometalic compound as photosensitizer. more recently, hybrid photocatalytic h production systems, hybphps, have been developed making use of the system units of both hetphps and homphps, homogeneous catalysts and heterogeneous photosen- sitizer semiconductors. more recently, interesting reviews have addressed separately each of the three system categories – but there is no inte- grated and comparative analysis of the three systems. the present review provides such an integrated overview of the photocat- alytic generation of h , and the influence of the photocatalytic units and process variables on h production rate and stability. this comparison has been made in terms of h production per unit time per gram of catalyst (molh ·gcat− ·time− ) for hetphps, turnover frequency (tof) for homphps and hybphps, and moles of h per mole of catalyst, turnover number (ton), as defined in eqns ( ) and ( ). the stability of the photocatalytic system, and the process effi- ciency are determined through the ‘quantum yield’ (qy) and ‘apparent quantum yield’ (aqy) eqns ( ) and ( ), – as indicators ∗ correspondence to: i ortiz, department of chemical and biomolecular engi- neering, etsiit, university of cantabria, avda. de los castros s/n, , san- tander, spain. e-mail: inmaculada.ortiz@unican.es a department of chemical and biomolecular engineering, etsiit, university of cantabria, santander, spain b laboratório nacional de energia e geologia, lisbon, portugal c umr , cnrs, université de bretagne occidentale, brest, france j chem technol biotechnol ; : – www.soci.org © society of chemical industry https://orcid.org/ - - - mailto:inmaculada.ortiz@unican.es 	a _ortizrangel_jchemtechandbiotech international journal of scientific research in science and technology copyright: © the author(s), publisher and licensee technoscience academy. this is an open-access article distributed under the terms of the creative commons attribution non-commercial license, which permits unrestricted non- commercial use, distribution, and reproduction in any medium, provided the original work is properly cited international journal of scientific research in science and technology print issn: - | online issn: - x (www.ijsrst.com) doi : https://doi.org/ . /ijsrst power generation using piezoelectric material akshaya hatey, vaibhavi koli, priti mishra, devanand bathe department of electronics engineering, kj somaiya institute of engineering and information technology sion, maharashtra, india article info volume , issue page number : - publication issue : july-august- article history accepted : july published : july abstract the energy crisis is the main issue of the world these days. the motto of the research work is to face the crisis. nowadays the demand for electricity is increasing day by day, so the ultimate solution to solve this problem is to use renewable sources of energy. in this project, we are generating electricity using non-conventional techniques. in this project, when human walks surrounding, some force is applied on the surface of the piezo sheet, this force can be used to generate electricity. the piezoelectric crystal has crystalline structure & ability to convert mechanical stress into electrical energy. keywords : piezo plate, battery, arduino, led, inverter, rectifier i. introduction the main principle of this project is the piezoelectric effect shown by metals. when person walks he puts some pressure or weight on the floor. the energy generating floor uses this to generate electricity for bending the piezoelectric material. this project not only provides an efficient source of energy but also a clean and pollution free environment. the main advantage of this project is that it is cheap & easy in installation power generated by the human pressure is stored and used for many applications. in engineering or household application, current is often described as being either direct current or alternating current. this term refers to how the current varies in time. direct current, as produced by example from a battery and require by most electronic devices, is a unidirectional flow from the positive part of the circuit to the negative part. if, as is most common, this flow is carried by electrons, they will be travelling in the opposite direction. ac current is any current that reverses direction repeatedly, almost always this take the form of a sine waves. ii. working principle the key principle behind the energy generating floor is the piezoelectric effect shown by metals. when a person walks he puts some pressure on the floor due to his weight and muscle power. the electricity generating floor uses this force to generate electricity by utilizing this force for bending the piezoelectric material. http://www.ijsrst.com/ https://doi.org/ . /ijsrst international journal of scientific research in science and technology ( www.ijsrst.com) | volume | issue akshaya hatey et al int j sci res sci & technol. july-august- ; ( ) : - iii. working a. system details . piezoelectric crystal: piezoelectricity is the electric charge that accumulates in certain solid material in response to applied mechanical stress. applying mechanical energy to a crystal called a direct piezoelectric effect. a piezoelectric crystal is placed between two metal plates. the metal plates collect these charges which can be used to produce a voltage & send an electrical current through circuit. . voltage divider : in electronics, a voltage divider (also known as a potential divider) is a passive linear circuit that produces an output voltage (vout) that is a fraction of its input voltage (vin). voltage division is the result of distributing the input voltage among the components of the divider. a simple example of a voltage divider is two resistors connected in series, with the input voltage applied across the resistor pair and the output voltage emerging from the connection between them. . rectifier and filter: rectifier and filter circuit is to filter out the output of piezo. bridge rectifier is an alternating current (ac) to direct current (dc) converter that rectifies mains ac input to dc output. they can be constructed with four or more diodes or any other controlled solid-state switches. . battery: the battery is connected to the inverter. this inverter is used to convert the -volt d.c to the volt a.c. this volt a.c voltage is used to activate the loads. . clt sensor : cross-laminated timber (clt) is a wood panel product made from gluing together layers of solid-sawn lumber. regular timber is basically an anisotropic material means that the physical properties change depending on the direction at which the force is applied. but by gluing layers of wood at right angles, the panel is able to achieve better structural rigidity in both directions. it is similar to plywood but with distinctively thicker laminations . lcd screen : a liquid-crystal display (lcd) is a flat panel which uses the light-modulatin properties of liquid crystals combined with polarizers. . lcds are available to display arbitrary or fixed images with low information content, which can be displayed or hidden, such as preset words, digits, and seven-segment displays, as in a digital clock. . led display : a led display is a flat panel display that uses an array of light-emitting diodes as pixels for a video display. led displays can offer higher contrast ratios than a projector and are thus an alternative to traditional projection screens. b. block diagram fig . http://www.ijsrst.com/ https://en.wikipedia.org/wiki/electronics https://en.wikipedia.org/wiki/passive_circuit https://en.wikipedia.org/wiki/linear_circuit https://en.wikipedia.org/wiki/voltage https://en.wikipedia.org/wiki/resistor https://en.wikipedia.org/wiki/series_and_parallel_circuits international journal of scientific research in science and technology ( www.ijsrst.com) | volume | issue akshaya hatey et al int j sci res sci & technol. july-august- ; ( ) : - c. implementation . the aim of this project is to generate electricity using footstep. the output of the piezo is ac in nature. . when a person puts pressure on the piezo sheet floor the output which is produced by the piezo sheet is given to the rectifier and filter connection suing rectifier ic w v . a . . voltage obtained by the rectifier filter connection can be further sent to the voltage divider circuit. it will sample the voltage successfully. . this sample output voltage given to the arduino pin which is connected to the lcd display. . at the output when we put the pressure on the piezo crystal it will generate the voltage upto v. . the sensor is connected to measure the flow of current through dc load. . piezos are connected in series parallel manner. . the arrangement of piezo crystal is placed on a hard wooden plank to protect the sheet from physical damage. fig. fig. fig. iv. expected result when we applied pressure on the piezoelectric sensor the voltage deflection is sensed. i.e when we apply pressure and realesed it then the lcd display shows the deflection. this deflection depends upon the applied pressure and the type of piezoelectric material we used. as we connected piezos in series parallel manner, we expected that it will genenrate the voltage upto v. the voltage generation is totally depends upon how much we applied pressure. v. conclusion here we are introducing a new source or way of generation of electricity. running cost is negligible of the project because here no special fuel is required like other power generating stations. there is no pollution with this technology as compared to other http://www.ijsrst.com/ international journal of scientific research in science and technology ( www.ijsrst.com) | volume | issue akshaya hatey et al int j sci res sci & technol. july-august- ; ( ) : - power generating technologies, hence it is eco- friendly in nature. untapped mechanical energy associated with footsteps is used for generation of electricity. for more generation of electricity, more pressure is required hence the project can be successfully implemented in crowded areas. vi. future scope this project can be successfully implemented in airports, railway stations and the technology can be incorporated to generate power in the following applications • below railway tracks • school/ college • staircases • in car tires • in boxing panel vii. references [ ]. power generation using piezoelectric material vikram rathod , shubhada janotkar, nikhil daundkar,ajay mahajan,anup chaple (feb - ) [ ]. harshal patel, brijesh mistry, a paper on footstep energy production, ijirst international journal for innovative research in science & technology| volume | issue | may , issn (online): - [ ]. marshiana. d, elizabeth sherine. m, sunitha. n, vinothkumar. footstep power production using piezoelectric sensors, research scholar, department of eie, sathyabama university, chennai, india,july- issn - [ ]. kiran boby, aleena paul k, anumol.c.v, josnie ann thomas, nimisha k.kdept of eee, mace, kothamangalam, footstep power generation using piezo electric transducer, international journal of engineering and innovative technology (ijeit)volume , issue , april ,issn: - [ ]. electric power generation using piezoelectric crystal p.balaji naga yashwanth, gautham kumar moka, donepudi jashwanth. (oct - ) [ ]. richard, michael graham, ( - - ). "japan: producing electricity from train station ticket gates". tree hugger. discovery communications, llc. [ ]. ieee standard on piezoelectricity, standards committee of the ieee ultrasonic’s, ferroelectrics and frequency control society, ansi/ieee std - ( ). cite this article as : akshaya hatey, vaibhavi koli, priti mishra, devanand bathe, "power generation using piezoelectric material ", international journal of scientific research in science and technology (ijsrst), online issn : - x, print issn : - , volume issue , pp. - , july-august . available at doi : https://doi.org/ . /ijsrst journal url : http://ijsrst.com/ijsrst http://www.ijsrst.com/ https://doi.org/ . /ijsrst http://ijsrst.com/ijsrst energy storage for energy security and reliability through renewable energy technologies: a new paradigm for energy policies in turkey and pakistan sustainability article energy storage for energy security and reliability through renewable energy technologies: a new paradigm for energy policies in turkey and pakistan riaz uddin ,*, hashim raza khan , asad arfeen , muhammad ayaz shirazi , athar rashid and umar shahbaz khan ���������� ������� citation: uddin, r.; raza khan, h.; arfeen, a.; shirazi, m.a.; rashid, a.; shahbaz khan, u. energy storage for energy security and reliability through renewable energy technologies: a new paradigm for energy policies in turkey and pakistan. sustainability , , . https://doi.org/ . /su academic editor: vincenzo bianco received: january accepted: february published: march publisher’s note: mdpi stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. copyright: © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (https:// creativecommons.org/licenses/by/ . /). haptics, human-robotics and condition monitoring lab (national center of robotics and automation), department of electrical engineering, ned university of engineering & technology, karachi , pakistan; mshirazi@ee.knu.ac.kr neurocomputation lab (national centre of artificial intelligence-ncai), department of electronic engineering, ned university of engineering & technology, karachi , pakistan; hashim@neduet.edu.pk department of computer and information systems engineering, ned university of engineering & technology, karachi , pakistan; arfeen@neduet.edu.pk department of governance and public policy, national university of modern languages, islamabad , pakistan; atharrashid@numl.edu.pk department of mechatronics engineering, college of e&me, national university of sciences and technology, islamabad , pakistan; u.shahbaz@ceme.nust.edu.pk * correspondence: riazuddin@neduet.edu.pk abstract: forecasting the microeconomics of electricity will turn into a challenging process when electricity is produced through renewable energy technologies (ret). these technologies are mainly sunlight-based photovoltaic (pv), wind power, and tidal resources, which vigorously rely upon ecological conditions. for a reliable and livable energy supply to the electricity grid from renewable means, electrical energy storage technologies can play an important role while considering the weather effects in order to provide immaculate, safe, and continuous energy throughout the genera- tion period. energy storage technologies (ests) charge themselves during the low power demand period and discharge when the demand of electricity increases in such a way that they act as a catalyst to provide energy boost to the power grid. in this paper, we presented and discussed the renewable ests for each type with respect to their operational mechanism. in this regard, the renewable energy scenarios of pakistan and turkey are first discussed in detail by analyzing the actual potential of each renewable energy resource in both the countries. then, policy for the est utilization for both the countries is recommended in order to secure sustainable and reliable energy provision. keywords: renewable energy technologies; electricity storage system; sustainable energy; reliable energy; energy policy . introduction for secure, reliable, and sustainable energy production, electricity storage technologies (ests) play a vital role in the implementation of renewable energy technologies [ ]. ests provide several benefits, services, and smooth reliable operation to off-grid systems [ ]. through the services provided by the ests, smooth operations will certainly improve the power quality, reliability, strength, and competitiveness of the deployed renewable energy technologies (ret) [ – ]. various ests [ ] provide an overview and the detailed explanation of each energy storage technology by comparing the battery storage system in-terms of technical and economical features. in this regard, the work [ ] compares the lead acid battery with lithium ion battery in terms of capacity fading and partial charging of batteries. it describes the procedure of battery testing in off-grid renewable energy applications. sustainability , , . https://doi.org/ . /su https://www.mdpi.com/journal/sustainability https://www.mdpi.com/journal/sustainability https://www.mdpi.com https://orcid.org/ - - - https://orcid.org/ - - - https://doi.org/ . /su https://creativecommons.org/ https://creativecommons.org/licenses/by/ . / https://creativecommons.org/licenses/by/ . / https://doi.org/ . /su https://www.mdpi.com/journal/sustainability https://www.mdpi.com/ - / / / ?type=check_update&version= sustainability , , of several approaches were also proposed in the modeling of the battery. the work [ ] developed twelve models of lithium ion batteries. the datasets of each models were collected under three different temperatures of two lithium ion cell by utilizing swarm optimization algorithm. the algorithm derived the optimal model parameters of the two types of lithium ion cell. in research [ ], the techniques to determine the internal resistance of electro-chemical batteries are defined, such as lead acid, lithium ion, nickel metal-hydride, and electrochemical double layer capacitors-based batteries. the study also compares the ohmic resistance and dynamic internal resistance of the electrochemical batteries. similarly, the work [ ] developed the battery model/energy storage system and derived the parameters through a manufacturer’s data sheet by simulating it via the simpowersystems (sps) simulation software tool. the tool integrated the model of battery and performed complete analysis through simulation of hybrid electric vehicles power train. study [ ] reviewed the battery modeling of electric vehicles by changing its dimension from lithium ion battery to lithium sulphur batteries. it also discussed in detail the challenges for the deployment of lithium sulphur batteries on electric vehicle application. work [ ] carried out the modeling and simulation of the battery storage technologies, while deriving the size result of battery energy storage (bes) for residential areas of electricity peak shaving. in addition, the study [ ] used the particle swarm optimization algorithm to find the parameter of the lithium-ion battery in order to define the battery model in healthy or degraded state. study [ ] described each energy storage technology and compared the energy storage technologies in terms of efficiency, energy capacity, energy density, capital cost, response time, self-discharge, and life cycles in order to improve the energy security. analysis [ ] briefly clarifies the storage scheme using batteries and through recreation of the photo- voltaic framework and homer (a computer model developed by national renewable energy lab (nrel)), the real price of solar panel, lead acid, nickel-cadmium, nimh, and li-ion batteries were inferred. research [ ] explained the battery storage technologies in detail and investigated their application in power systems. research [ ] compared the bat- tery, ultra-capacitors, and fuel cell technologies for hybrid and plug-in hybrid vehicles by composing the hybrid electricity storage system through the utilization of ultra-capacitor, battery, and fuel cell technologies. another study [ ] compared and discussed the en- ergy storage technologies and briefly explained the applications of the energy storage technologies by highlighting its maturity level and potential level to connect the storage technologies, whereas the work [ ] did the cost-benefit analysis of electrical storage system by focusing on the capital cost, operation, maintenance, and replacement cost. similarly, work [ ] presents a review on several electricity storage technologies suitable for wind power application. in the research [ ], the literature talks about the life cycle assessment and metrics for calculation of input energy requirement and emission of greenhouse gas. it was developed for energy storage systems and applied to energy storage technologies, such as pump hydro storage (phs), compressed air energy storage (caes), and battery storage systems with vanadium and sodium poly sulphide type as electrolytes. the study also revealed that greenhouse gas emission by these storage systems will be lower when coupled with nuclear or renewable resources as compared to fossil fuel resources. further, phs gives lower greenhouse gas emission when integrated to nuclear or renewable energy resources, whereas caes emits lower greenhouse gas emissions when integrated with fossil fuel resources as compared to phs and battery energy storage (bes). the world desperately needs to de-carbonize the global energy sector in order to limit the effects of climate change by shifting towards renewable energy resources from fossil fuel [ ]. as the contribution of renewable energy technologies in the global power genera- tion increases rapidly, there is a dire need for energy storage systems. for improvement of power quality, proper provision to maintain the voltage level and constant frequency in energy storage technologies is required for the deployment of sustainable renewable energy technologies [ , ]. after reviewing the above-mentioned ests, it is necessary to sustainability , , of identify the optimum electricity storage technology to render the cost effective services and benefits to the power grid. based on this scenario, the energy storage for energy security and reliability through rets is studied for the case of turkey and pakistan. in this connection, we have the following objectives of this research: • the detailed study and comparison of renewable ests for each type with respect to their operational mechanism. • discussion of the renewable energy scenarios of pakistan and turkey to analyze the actual potential of each renewable energy resource. • proposal and recommendation of the policy for the ests application suggested for both nations to secure feasible and trusted power supply arrangement. the remaining part of the paper is organized as: section describes various ests and their deployment in the power sector along with discussion and comparison of different ests. section comprises renewable energy scenarios of pakistan and turkey. section states energy targets and storage policy along with energy storage policy recommendation for both the countries. section draws conclusions of the conducted study with the focus on policy recommendations. . energy storage technologies (est) a power repository system is broadly considered and installed in progressive nations of europe, asia, and australia for the arrangement of smooth, reasonable, and low-cost power supply to the particular local distribution frameworks [ ]. power storage technolo- gies are essentially divided into six categories depending on its development and utilization. therefore, figure portrays the number of ests accessible around the world, which can be utilized for diverse applications of power distribution to the end user depending upon the benefits and draw backs of each technology. figure . electricity storage technologies (ests) [ ]. considering the latest updates, most the developed nations, which are equipped with energy storage technology, have made the best use of a battery storage scheme, a pumped hydro storage scheme, and a thermal storage scheme in their agenda to supply low cost, maintainable, reasonable, and smooth power supply to end users. figure shows the cost summary of electrical energy storage technologies as tcc (total capital cost), while the sustainability , , of global capacity share of each storage technology utilized by different countries (i.e., specific storage/total) in terms of capacity and deployment ratio is depicted in figure [ ]. as shown in figure , the lowest cost is recorded for the case of super-capacitors-based energy storage systems. figure concludes that molten salt thermal storage covers the highest capacity and the deployment ratio, i.e., . gw and %, respectively. figure . cost summary of electrical energy storage technologies [ ]. figure . global operational electricity storage power capacity by technology [ ]. . . different ests with implementation in power sector electricity storage system plays an important role by deploying electricity storage technologies in different locations of power systems in order to provide safe, reliable, and affordable electricity [ ]. charging/discharging of storage technologies plays a significant part in short and long interval of time for energy storage capacity. it also depends on high/low output power to the power grid. ests mainly depend upon its charge and discharge time, which takes seconds to hours to charge and discharge completely [ ]. moreover, each est is best suited for particular application of kw level to gw power of the system requirement. for bulk energy storage, phs and caes are most suitable for this application due to its discharge time for tens of hours economically [ , ]. on the sustainability , , of other hand, flywheel energy storage technology discharges ( kw– kw), high power super-capacitor storage discharges ( kw– mw), and superconducting magnetic energy storage discharge ( mw– mw) in a very short period of time, i.e., few seconds, but with rapid high power rating, which makes it suitable for ups (uninterruptible power supply) application or improves the quality of power [ , ]. similarly, flow batteries like zinc-chlorine flow battery, zinc air flow battery, zinc bromine flow battery, vanadium redox flow battery, and polysulfide bromine flow battery charges and discharges the power rating from kw– mw. it also takes hours to discharge at rated power [ , , ]. in addition, high temperature battery sodium sulphur (nas) takes hours to discharge at rated power from mw to mw. on the other hand, lithium-ion battery discharges at ( kw– mw), lead acid batteries ( kw– mw), high energy super-capacitors storage ( kw– kw), advanced lead acid battery ( kw– mw), nickel cadmium battery ( kw– kw), sodium nickel chloride battery ( kw– mw), and nickel-metal hydride battery ( kw– mw) mainly take minutes to discharge at rated power in order to provide the services to the grid [ , , ]. electricity storage systems can be used in three main segments of the electricity sector named as grid services, behind the meter application, and off-grid applications. below, we briefly describe different ests regarding the suitability of electricity storage technology for different applications in these three main segments of electricity sector: • pumped hydro storage technology is suitable for frequency restoration reserve, energy shifting/load leveling and island grid applications [ ]. • compressed air energy storage technology is best suited for frequency restoration reserve, energy shifting/load leveling and island grid application [ ]. • fly wheel storage technology suits for the application to enhance frequency re- sponse, frequency containment reserve, increased power quality, peak shaving, and island grid. • flooded lead acid storage batteries and valve-regulated lead acid batteries are suitable to enhance frequency response, frequency containment reserve, self-consumption for small residential (community) storage, increased power quality, peak shaving, time of use, nano-off grid, village electrification, and island grid. • lithium-ion storage batteries stand ideal for enhancement of frequency response, frequency containment reserve, self-consumption for small residential (community) storage, increased power quality, peak shaving, time of use, nano-off grid, village electrification, and island grid applications [ ]. • sodium nickel chloride storage battery is best suited for enhancing frequency response, frequency containment reserve, community storage, increased power quality, peak shaving, time of use, village electrification, and island grid applications [ , , ]. • vanadium redox flow battery is ideal application for frequency restoration reserve, energy shifting/load leveling, self-consumption for small residential (community) storage, peak shaving, time of use, village electrification, and island grid applica- tion [ ]. • zinc bromine flow battery is ideal for applications such as self-consumption for small residential areas, community storage, time of use, village electrification, and island grid [ , ]. . . discussion and comparison on different ests pumped hydro storage (phs) technology is usually used in peak demand of electricity to reduce the power generation cost. presently, phs plays an important role in storing the energy worldwide, which constitutes % share of world’s generation ( gw capacity). an additional benefit of phs technology is the low discharging rates at idle scenario and it can also store energy for a longer period of time as compared to electro-mechanical flywheel energy storage technology. the drawback of the flywheel energy storage technology is its high discharge rates at idle scenario. on the other hand, it also provides high power ratings in terms of voltage regulations and frequency within the electricity system [ ]. hydrogen sustainability , , of ammonia storage technology has gained attention in terms of reliable and efficient means available, irrespective of the region, policies, and conditions. this storage technology can be utilized to gain the maximum output for energy storage as well as to store the energy for a longer period of time. in case of bulk power generation, we can store energy by using the hydrogen ammonia technology and utilize it according to demand for a longer period of time. in order to compare ests in different common specifications, table provides a useful analysis of all technical indicators, which details the five different energy storage systems separately according to their features, capacities, and issues [ ]. table . comparison of technical indicators of ests [ ]. storage systems s.no technical indicators pumped hydro storage (phs) compressed air energy storage (caes) flywheel energy storage electrochemical battery energy storage (bes) hydrogen based storage commercially proven yes yes r & d proven initial stage ready to implement power capacity – mw about – mw (with – h discharge time) kw flywheel ees and store kwh for a few seconds capacity of mw with h as the discharging time ready to implement operational cost . €/kw-year no significant reduction of cost . €/kw-year between . and €/kw-year initial stages construction and installation costs average costs €/kw average costs €/kw average costs €/kw average costs €/kw (li-ion batteries) the capital costs of electrolysis itself varies in different applications. efficiency . – . . – . . – . . – . (li-ion batteries) net electrolysis efficiency up to % until now, countries have fully utilized the pumped hydro storage technology in en- ergy transition for secure, affordable, and reliable energy provision to their consumers [ , ]. in this regard, china stands as a leading case with a large capacity of phs technology ( gw) followed by japan ( gw capacity). the data for other countries includes usa ( gw), spain ( gw), italy ( gw), and the lowest capacity of energy storage through phs among countries is reported for denmark, whereas, non-phs storage stands at gwh ( ). thermal storage capacity (tsc) is . gw ( . %) in the recent scenario, electro-chemical battery capacity is . gw ( . %), and electro-mechanical storage battery capacity is . gw ( . %) [ ]. the shared capacity of ests with respect to top coun- tries are as follows: china (electro-chemical capacity . gw, tsc . gw, phs capacity gw), followed by japan (electro-chemical capacity . gw, phs capacity . gw), usa (electro-mechanical . gw, electro-chemical capacity . gw, tsc . gw, phs capacity . gw), spain (tsc . gw, phs capacity . gw), germany (electro-mechanical . gw, electro-chemical capacity . gw, phs capacity . gw), italy (electro-chemical capacity . gw, phs capacity . gw), india (tsc . gw, phs capacity . gw), switzerland (phs capacity . gw), france (phs capacity . gw), republic of korea (electro-chemical capacity . gw, phs capacity . gw). it is estimated that the electricity storage demand for stationary [ ] and mobile applications will increase rapidly from . twh ( ) to . – . twh ( ) [ ] if the contribution of the deployment of renewable energy technologies doubles as compared sustainability , , of to the present scenario. non-phs storage is estimated to rise up to – gwh by depending on the falling cost of the battery. hydrogen ammonia storage technology is estimated to rise to – gwh of energy storage by . it is estimated that battery deployment capacity in stationary application will increase from gwh to – gwh by [ ]. in addition, the utility sector utilized the battery energy storage (bes) system of gwh ( ), which will rise to an estimate of gwh to gwh by [ ]. in the renewable energy map analysis [ ], it is concluded that by , electricity energy storage will reach gw, when the installed capacity of solar and wind plant capacity will soar to gw. the share of storage capacity in , will be gw, which will constitute gw capacity from electric vehicle storage, gw from phs, and gw from stationary battery storage [ ]. . renewable energy scenario of pakistan and turkey . . pakistan scenario the entire land of pakistan is , km with . million people [ ]. up until , electricity generation in pakistan was . twh [ ]. pakistan is facing severe energy crises and the facts [ ] reveal as follows: ( ) the role of fossil fuel remains the highest in form of oil and gas, i.e., . % resource consumption in order to produce electricity in in pakistan; ( ) the share of power production through hydro power plants is . %, nuclear power plants stand at . %, and renewable energy . %. it is a dire need to make a strategy to overcome the prevailing crisis and formulate a clear goal keeping in view the decreasing levels of fossil fuel in the world simultaneously reducing massive expenditures incurred on its import [ ]. pakistan is spending % of its reserves on importing the fossil fuel, which is a great burden on its crumbling economy [ ]. from energy security, sustainable energy resource, climate change, and economic considerations, alternative energy resources can prove to be the best option in hand in the present scenario [ ]. pakistan’s ministry of energy and other responsible departments, such as pakistan water and power development authority (wapda), karachi electric supply company (kesc), and independent power plant (ipps), are planning and executing several renewable energy projects by establishing plants for wind energy, solar power, hydel power, and biogas across the country [ ]. in order to provide low-priced electricity, transformation of the existing resources of energy from thermal plant (fossil fuel) to renewable energy resources is taking place for clean energy production. with this shift of renewable energy technologies, there will be less or no reliance on fossil fuels as the main source for energy. moreover, there will be positive effects on the environment in both the countries. according to study [ ], the demand increases up to % annually. the difference between demand and supply was mw in , but it increased to mw in [ ]. according to the study [ ], pakistan faced an energy deficit of mw in and on a daily basis, there was load-shedding of – h across the country continuing from . according to the pakistani government, the prediction was that the energy crisis in pakistan would completely vanish in and the country would produce surplus energy of mw [ ]. pakistan is still facing the energy crisis with a shortfall of mw due to transmission losses [ ]. according to this report, pakistan was generating . mw of electricity through modern renewable energy technologies in – , which was added to the national grid [ ]. still, the pakistani energy scenario heavily relied on oil to produce electricity, but in – , a shift from oil to gas could be witnessed in the power sector to generate electricity for industrial, household, commercial, and transport sector consumption. as compared to , the fossil fuel cost increased in resulting in . % decrease in the total energy supplies [ ], which badly affected the economy of the country. the contribution of fossil fuels remains the highest in the form of oil and gas, i.e., % to generate electricity. despite all these efforts, pakistan is unable to fulfill the demands of energy requirement. this situation mainly affected the industrial sector resulting in the export minimization and causing adverse effects on the economic growth of the country. the total installed capacity sustainability , , of in terms of fossil fuel, hydro power, and nuclear power plant to generate electricity in pakistan up to july was reported to be , mw with the generation of , gwh [ ]. pakistan deployed several wind power plants, solar photovoltaic plants, and biomass plants in order to cope with the energy crisis. the summary of power capacity installed and electricity generation through the renewable energy technologies is shown in figures – [ ]. the share of the hydro power renewable energy technology is far high as compared to other modern renewable energy technologies. the installation capacity and energy production of each renewable energy technologies are summarized in figures and . similarly, the detailed usage of solar-, wind-, and biomass-based capacity and power generation are shown in figures and , respectively. figure . total installed capacity of renewable energy in pakistan up until [ ]. figure . total electricity generation through renewable energy technologies of pakistan up until [ ]. sustainability , , of figure . total capacity of modern renewable energy technologies of pakistan up until [ ]. figure . total electricity generation through modern renewable energy technologies of pakistan [ ]. . . turkey scenario turkey has , km territorial area [ ] with a population of . million [ ]. total electricity generation for turkey was recorded to be , gwh up until . according to the observation, turkey depends mainly on coal ( %), natural gas ( %), hydropower ( %), and renewable energy ( %) [ ] to generate electricity. turkey imports % of these total primary energy supplies (oil, natural gas, coal), which is certainly an enormous load on the turkish economy [ , ]. in this regard, the research [ ] analyzes the operational performance and investment performance of natural gas-, oil-, and coal- based thermal power plant operated by public and private sectors of turkey. it also derived some useful efficiency scores based relationships between the thermal power plants in terms of operational and investment cost [ ]. with the % increase of energy demands in turkey annually [ ], there is a lurking need to increase energy production. according to the observation, the major share in the rise of demand is due to the industrial sector. the industrial sector energy demand was expected to reach to twh due to the exports of industrial goods and agricultural processed products to the european open market (without custom duty) till [ ]. in order to fulfill the requirement of energy demand and supply, and with a vision [ ] to utilize the % renewable energy technology resources to generate ( , gwh) electricity till , turkey will be less dependent on fossil fuel and can also get rid of the carbon tax [ ]. sustainability , , of turkey lies in a perfect region where it can utilize the maximum resources of modern renewable energy technologies to cope with the upcoming energy demand in the country. by utilizing the renewable energy resources, such as wind power technology, solar power technology, biomass technology, and geothermal energy technology, turkey has the poten- tial to produce twh of energy, which is double the energy generation compared to electricity generated in [ ]. moreover, this renewable energy technology does not emit co as compared to the utilization of the traditional fossil fuel used for electricity generation, which is not only harmful for the environment, but lays heavy costs on the national economy of turkey in terms of conventional fuel (coal, gas, oil) import costs. energy security and sustainable energy supply is paramount for the turkish state as only dependence on fossil fuels would make the state dependent on the stakeholders causing risk to the national security of the turkish state. according to the collected facts in the years – , % of electricity generated in turkey was thermal-based (gas, coal, oil), where renewable-based electricity generation was only . % ( . % hydropower, . % others) [ ]. turkey has a great potential of wind power plant as shown in figures – and as of now, companies have installed wind power plants across the country. figure . total capacity of renewable energy technologies of turkey up until . figure . total generation through renewable energy technology up until . sustainability , , of figure . total capacity of modern renewable energy technologies of turkey up until . figure . total generation capacity of modern renewable energy technologies up until . . energy targets and storage policy policy targets regarding energy are broadly classified into five different sectors, i.e., pri- mary energy supply, final energy consumption, electricity, transport, and heating/cooling system. in pakistan’s case, an energy crisis-based scenario sets a target and recommends a strategic policy to overcome the confronting energy challenge through the deployment of modern renewable energy technologies. several projects of renewable energy technologies are under development to meet the current energy demands and fulfill the requirement by utilizing the available natural resources of energy in power and transport sectors. it is believed that by the middle of june , pakistan will be in a position to produce surplus energy, which will definitely impact its socio-economic growth. pakistan should adopt the electricity storage policy in order to produce affordable, safe, secure, and sustainable energy, whereas, in turkey’s case, the nation aims to fulfill the national energy demands focusing on primary energy supply as well as generating electricity to export it to the other european countries. in this regard, kv akhaltsikhe-borcka of transmission line sustainability , , of is under construction with a dc (direct current) back to back station at georgian side. moreover, turkey-romania kv hvdc (high voltage direct current) submarine cable under the black sea carrying mw is proposed and feasibility studies are in progress. in addition, turkey-iraq kv cizre-musul transmission line is in the planning stage and turkey-iran transmission line of kv khoy-baskale-van is under construction with dc back to back interconnection. . . discussion on energy storage policy energy storage policy has become a significant issue for both developing and de- veloped countries in terms of reliability, security, sustainability, and affordability. many countries have a national energy policy entailing the integration of the various renewable energy technologies with effective energy storage systems in order to make the power sector reliable and sustainable. moreover, this policy will play a significant part in reducing the effect of co emissions. there is an active global movement going on for the adoption of % employment of renewable energy technology in power sectors. energy storage is directly proportional to deployment of modern renewable energy technologies. on a global scale, every country shows interest in investing money in the power sector for energy stor- age systems for the implementation of renewable energy technologies. usa, australia, and china are pioneers in this field, which uses electro-chemical storage, electro-mechanical storage, and thermal storage in its energy infrastructure for reliable operation of the power sector. hydro pumped storage, which is a mature field, has made its place in the power sector and many countries adopted it in their national policy to store the energy. on the other hand, the prices of battery storage system have fallen down and are expected to move down with the passage of time. the lower the price of the battery storage system, the higher the expectation of the deployment of renewable energy technologies. for the active implementation of the energy storage technologies along with the renewable energy technologies in the power sector, the support of the public sector stands as paramount. the second step in this regard is a clear framework of promoting the implementation of renewable energy technologies in the current infrastructure to fulfill the demand of energy and phasing out all subsidies on fossil fuel import and nuclear energy production. in order to achieve the smooth, fast, and cost effective transition to energy storage technologies, government needs to adopt a national legislative act, which ensures to provide the opportunity to private entities to invest money in the deployment of renewable energy technologies as well as energy storage technologies. in this regard, the following are the key recommendations in terms of the deployment of energy storage technology for policy makers for the utilization of the maximum potential of renewable energy resources by integrating it with the latest storage technologies. . . energy storage policy recommendation . . . new channels and mechanisms to attract investors the german renewable power sources act (eeg) is a good and ideal model of policy guideline in which they establish the permanent feed-in-duty for the deployment of re- newable energy systems. this policy guideline gives reduced upfront cost in wind- and solar-based technologies. this policy framework allows preferential award for investment in the renewable energy projects. the german scheme has certain merits and demerits [ ], such as the feed-in tariff mechanism posing higher risks on large installations of solar pv with longer project durations as there are higher uncertainties about remuneration levels at project completion time. feed-in tariffs involve lower costs of equity and cost of debt than tenders. it has been observed from the data and statistics of different countries that by applying the tenders instead of a feed-in-tariff, this strategy will reduce the investment cost to deploy more renewable energy technologies in the power sector as tender becomes costly for consumers. tenders are only applicable for capacities above mw and feed-in-tariff sustainability , , of process should be adopted for capacity below mw to promote the renewable energy technologies as well as integration of storage technologies. since there are some trade-offs using feed-in tariffs and tenders to remunerate different scales of renewable energy projects [ ], hybrid support mechanisms [ ] are becoming popular gradually and a new political mechanism also needs to be implemented in order to invest in renewable energy, storage technology, and their integration to achieve the reliable and affordable electricity. hybrid renewable power plant remuneration (hybrid support mechanism) [ ] was introduced and termed as a reformed version of feed-in-tariff and tenders in energy sector. . . . phasing out subsidies on non-renewable resources it is advised that the governments promote and encourage renewable energy tech- nology by giving subsidies in taxes for the pioneer investors in this sector. it is also recommended to increase taxes on import of fossil fuels discouraging this trend and saving foreign reserves in parallel. this scheme would increase spending of public funding on infrastructure projects and education by the government. the study [ ] concludes that the nuclear energy contributes to environmental pollution in pakistan. this study further suggests certain actions and measures to make nuclear energy a clean source of energy in pakistan: • improvement in the infrastructure for nuclear generation. • establishment of independent regulatory body to achieve the threshold level of nuclear share and enhancing nuclear waste management facilities. • the checks are required for operational performance, efficiency, and monitoring to avoid serious irreversible consequences to humanity and the environment. . . . power storage sector as tax-free zone this sector can be categorized as exempted from tax on acquisition of property, pro- curement of necessary equipment, commercialization, financing, and trading. this will ease the making of relevant business plans by entrepreneurs and they will quickly achieve the break-even point in their financial books. this will minimize the risk of loss and maximize the return on investment in the future. it will also build the trust of businessmen community on the government. . . . introducing carbon and radioactive tax by introducing the carbon and radioactive tax, the trend of power generation from fossil fuel will be declined and most of the countries will switch slowly and gradually to renewable energy and storage technologies. this fact cannot be ignored that fossil fuel reserves will be depleted in the future, so the cost of fossil fuels and imposed taxes will be increased gradually, which will push the world to shift to alternate approaches. . . . research and development for renewable energy research and development is the key factor for success in a particular field. it is rec- ommended to create awareness in the younger generation of the deployment of renewable energy projects and reducing reliance on fossil fuels by taking the ministry of education on board. universities can play a better role by connecting undergraduates, ms students, phd scholars, and young entrepreneurs to do research work in this sector. business and technology incubation centers should encourage business ideas in renewable energy and energy storage sector. similarly, it is necessary to force local research institutes to apply for collaborative research with international researchers and funding agencies. . . . pilot projects and their enhancement the government should adopt a clear policy to take an initiative after feasible study to deploy the most suitable energy storage technology with the renewable energy technologies and introduce it as a pilot project. the pilot projects can be improved using a learning-by- sustainability , , of doing approach, so that energy storage technologies can be utilized to their maximum in the power sector in order to reduce the emissions of co and dependence on fossil fuel imports that lay a heavy cost on the national economy. . . . safe and secure platform to the competitor a subsidy and tax reduction policy should be implemented on renewable energy technology deployment along with energy storage technologies. more competitors will show their interest in energy storage systems and ultimately storage technology will be employed for every renewable energy technology installation. . . . learning from positive case studies it is impossible for the user to learn and deploy most suitable storage technologies. user should consider the best-case result in which battery storage or thermal storage technology has played a vital role and replicate the idea if the condition and environment suits the needs and demands. table provides a brief summary of the policy recommendations. the right mark indicates the suitability and applicability of the policy recommendation in the respective countries. n/a is the abbreviation of “not applicable”. table shows the recommendations for the renewable energy and energy storage development of pakistan and turkey. these recommendations include the adoption of the mechanisms to attract investments, phas- ing out subsidies and incentives on non-renewable energy projects, tax exemption from renewable energy projects, creating more competitors for providing relief to consumers and learning from other countries through positive case studies. table also highlights the other recommendations applicable for pakistan, such as pilot project initiative, r&d in zero emission, and introduction of radioactive tax to promote renewable energy development. in case of turkey, the introduction of a carbon tax may prove to be beneficial for renewable energy development. table . summary of above policy recommendations. s.no recommended policies pakistan turkey enable the direct investment in renewable energy phasing out subsidies tax exemption from ret introducing carbon tax n/a introducing radioactive tax n/a research and development in zero emission and ret n/a pilot projects initiative n/a develop more competition to provide relief to consumers learn from others through positive case studies . conclusions in this paper, we have performed comparative analysis of different energy storage technologies with the emphasis on energy security and reliability based on the renewable energy scenario of pakistan and turkey. we have compared different energy storage technologies in terms of some technical indicators and suitability of applications useful for the deployment of renewable energy projects. we have also reported the statistics of the deployment of energy storage technologies in the globe and its expected increase until based on renewable energy scenario. the presented data and analysis prove that pakistan and turkey have not fully exploited the renewable energy potential in the respective countries. as pakistan and turkey are dependent on the imports of fossil fuels, they may set an example for other developing countries willing to transform their energy sector sustainability , , of towards renewable energy resources by utilizing the maximum potential of renewable energy and its cost effective integration with the energy storage technologies. this change is inevitable due to global environmental and ecological effects pushing the global community to impose certain taxes on the localities releasing co in the environment. the mentioned facts and standpoints encourage both the countries to develop, design, and formulate a very strong storage policy, which is easy to implement and should be bene- ficial in the long run. the policy recommendations include the adoption of the mechanisms to attract direct investments, phasing out subsidies on non-renewable energy resources, tax exemption from renewable energy projects, creating more competitors for providing relief to consumers, imposing carbon tax, and learning from other countries through positive case studies. the policy also suggests cost effective integration of electricity storage technology with the renewable energy technology as the prices of the electricity storage technologies continue to reduce with the passage of time according to irena database. author contributions: conceptualization, r.u.; methodology, r.u.; validation, h.r.k., a.a., m.a.s. and a.r.; formal analysis, h.r.k. and a.a.; investigation, r.u. and h.r.k.; resources, h.r.k., a.a., a.r. and u.s.k.; data curation, m.a.s.; writing—original draft preparation, r.u.; writing—review and editing, m.a.s.; visualization, m.a.s.; supervision, r.u.; project administration, a.r.; funding acquisition, u.s.k. all authors have read and agreed to the published version of the manuscript. funding: this work was supported by the higher education commission of pakistan under grants titled “establishment of national centre of robotic and automation (df- - )”. institutional review board statement: not applicable. informed consent statement: not applicable. data availability statement: not applicable. 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( . ): . legislative and policy in energy efficient designing and renewable energy sources – application in serbia mila pucar, marina nenković-riznić this paper analyses political and legislative frames in the field of energy efficient building and renewable energy sources in planning and implementation in serbia. „development strategy until .“ is reviewed in concise portrait. this strategy maps a way for the application of energy services of much higher quality than ones offered at a present day. it reviews relevant laws concerning the subject, as well as institutions, programs and their implementation. basic principles of energy policy in serbia and their achievement are also given by that strategy. serbia's energy policies are designed to allow new legislative, structural, organizational, institutional, and economic frames and visions of unification of serbian energetics into regional and pan-european integrations. one of the key factors is the inclusion of sustainable development and energy efficient design concerned policies. application of these, almost completely neglected, energy sources, for which there is high potential in serbia, would allow preservation of primary energy sources and local environment. this potential hasn't seen significant research, and therefore, neither the technical improvement. apart from that, one of the goals of wider application of renewable energy sources is lowering the poverty level. this helps avoiding the already used “dirty development” method. keywords: energy policy, legislative, renewable energy sources, energy efficient planning, serbia. introduction energy crisis that was prominent during the 's was an after-effect of disturbances on the oil market. fossil fuel reserves (the one that are in current and presumed future, usage) are limited, and according to different predictions, most of them will be depleted by the middle of this century, when the next energy crisis might occur. energy crisis, followed by an ecological crisis, both on local and global levels, were primary factors in the formation of the general attitude that the current methods and levels of both energy exploitation and means of its consumption are unsustainable. this attitude clearly comes from the range of data considering the water and air pollution, chemical changes in the atmosphere, ozone holes, soil degradation, extinction of many plant and animal species, declination of the forest regions, etc. (kaya, .). energy, ecologic and economical crises led to the definition and wider acceptance of the unsustainability of traditional resources and the environment's limited capacity on local and global scale. sustainable development concept could be transposed into all human activities (baumgartner, zielowski, .). out of the overall energy produced, around % is used on communal buildings, which makes measures that could potentially lead to the reduction of these figures very important in the process (walker, devine-wright, ). the reduction of energy consumption in communal buildings (in heating, cooling, illumination, etc.) is possible through the utilization of the energy efficient urban planning and building design methods and with the application of the bio-climatic planning and design principles with an emphasis on renewable energy sources (further r.e.s.). there is a need for strategic, politically- legislative frames, institutions, programs and instruments for the realization and implementation of the sustainable development concepts. energy eficiency and renewable energy sources (r.e.s.) energy efficient buildings the european directive (directive / / from . . ) on energy consumption in communal buildings, which is an obligation for the member countries to implement in their s p a t i u m national legislatives since january . ensured that building standards for the whole european union are unified. this, while not demanding additional financial burden, allowed a more efficient usage of energy in european communal buildings. at the same time, this directive ensured an increase in the quality of life for the population. this, and similar measures, which are targeted at a broader public of energy consumers, represent basic component of the european union’s strategy towards the facilitation of responsibilities undertaken by the ratification of the kyoto protocol (jager-waldau, ). but, it is not always applied in european union, mainly because all the countries still are in a kind of unsustainable condition, using traditional energy resources, instead of renewable one. entire european union will implement the common methodology for calculation of the communal energy consumption, which will consider climate differences as variables. member countries will define minimum in standards for consumption which will be applied both, in the design of new buildings, and in the significant reconstructions of old ones. for the most part, these standards will be based on contemporary or planned european norms. energy certification system will allow owners, tenants and users to be better informed on the consumption of the energy in the building they buy or rent. establishing the energy efficiency will encompass several different elements, like thermal isolation, heating system, cooling, natural ventilation as well as passive lighting and heating using solar energy. positive factors could include heating using solar energy, electric energy production, distant heating and co-generation of electric energy and heat. local climate limitations, because of its high diversification on the territory of europe, play an important role in the facilitation of the energy efficiency in communal buildings. on the other hand, communal energy consumption in buildings in serbia is near % of the overall consumption. lighting, heating, cooling and hot water in serbian homes, offices and recreational buildings consume more energy than it is used in transport or industry. this trend is growing with the amount of consumed energy, because the growth in life standard leads to a broader application of the air conditioning and heating systems. it means that present conditions in serbia are not so promising, especially because of the fact that serbia has a large potential in renewable energy sources, and not using almost any of it for her basic needs in energy. thinking about the future energy consumption, we must not forget the fact that renewable energy sources such as geothermal energy, solar energy, and energy of hydro power plants could substitute a large amount of traditional energy sources (oil, coal, wood, etc.) which are causing an green house effect. domestic strategies should not base themselves exclusively on the european directives, but they should seek instead a model appropriate to the local environment, political and financial conditions and also local legislative. serbia must adjust european traditional values to our local contextual conditions. renewable energy sources (res) renewable energy sources (res), apart from other energy sources like fossil fuels or nuclear fuel, are being naturally renewed. renewable energy sources are apparently inexhaustible, but only if the current natural conditions are not disrupted. however, res are limited in intensity (hein, ). all of the aforementioned renewable energy sources are of interest for serbia, except the ones related to the energy from the sea. renewable energy sources are clean energy sources, and they remarkably contribute to the decrease of air, water and soil pollution. in the last decade, great importance has been given to the problem of global warming and the greenhouse effect, which is the consequence of an increased content of carbon-dioxide in the upper layers of atmosphere, preventing reflection of solar radiation from the surface of the earth through the atmosphere. the increased use of res will contribute to increasing reliability of energy supply, will help in sustainable development of the energy sector and will increase the standard of living, particularly in rural areas. the reduction of harmful gases emission will improve quality of the environment. serbia is relatively poor in fossil fuels. it is expected that in the near future the share of res will be significantly increased in the energy balance of serbia. serbia with its territory of . km has a natural suitability for use of renewable energy sources. it is estimated that the biomass has the greatest energy potential in serbia. biomass energy sources are distributed at an area of km covered with forests and at an area of . km used for agriculture. some locations are identified as appropriate for small hydro power plants. at more than hundred locations there are geothermal wells with water temperature ranging between and °c. it is a large amount of renewable energy sources which could be used instead of traditional once, not only in their original locations, but also they could be installed on a long distance through appropriate infrastructural equipment. so the large number of cities and villages could be heated from geothermal resources, or bio gas (originally received form bio mass or bio waste). it is possible to expect that in next several years private investors and stake holders will invest in hydro power plants, investigative works for geothermal resources etc. which could provide more clean energy to the whole country. strategy, laws, implementation serbian energetics development strategy till on may th . the national assembly of the republic of serbia ratified the „energetics development strategy until “, developed by the ministry of mining and energy. by appointing the council members of the serbian energy efficiency agency, the regulatory agency has been established. „energetics development strategy until “ represents a vision of local energetics development. it predicts that in the next ten or more years the s p a t i u m aspect of energetics activities will have improved quality, with simultaneous development of subjects included in energetics industry. it proposes new legislative, institutional, structural, organizational and economical frames and visions on integration of local energetics into regional and pan european integrations. the elementary premises of mentioned strategy are based on the assumed trend of socio-economic growth of serbia until year with respect to its current economic abilities. a new category, renewable energy sources, which includes biomass energy, hydropotential of small flows (with objects up to mw), geothermal energy and wind and solar energy, is planned for development and application because of serbia's natural capabilities for their exploitation in the processes of decentralized production of heat and electric energy. through these means it is believed that local users needs could be facilitated in a more qualitative and cost-efficient manner. energy potential of mentioned energy sources is considerable in serbia and is over m t.en per year. around % of the potential comes from the biomass exploitation. although for the most part of serbia's territory, there is a considerably higher number of sunny days (over hours), because of the high costs of solar receivers and auxiliary equipment, intensive usage of these technologies depends mostly on social and economic incentives for facilitation, implementation and exploitation of the national program for the renewable energy sources. serbian energy policy energy law ("official gazette of the rs", n . / ) in energy policy section includes measures and activities taken for achieving long-term objectives in the energy sector, and particularly: creating conditions for stimulating the use of renewable energy sources and combined heat and electrical power generation, and providing conditions for promoting energy efficiency in carrying out energy activities and energy consumption energy sector development strategy in energy law is defining long term development objectives of specific energy activities, development priorities, sources and methods of providing the required energy quantities and incentives for increasing energy efficiency instruments for implementation of energy policy goals in serbia energy policy realization tools are: • legislative instruments – are concerned with the energetics law, and other, following packages of law instruments concerning the regulations of new functioning methodologies. • institutional instruments - which define the role and mission of the energetics agency, which includes innovations into technical work practices, business of energetics subjects and development of the energy sector, and defines a methodology for definition of the justified costs of production, transport and distribution of the electrical and heat energy and natural gas. • structural and organizational instruments - are concerned with methods of reorganization of current vertically integrated eps and nis, into divided, productive and profit units, economically motivated for rational functioning and financially capable to invest into their own development. • economic and financial instruments - are concerned with the rates and price policies of the energy sector. • system instruments - are concerned with facilitation of the energetics statistics system and founding of the national fund for energy efficiency. it is important to know that all of these instruments must be included in global strategy of the res and energy efficiency implementation in serbia. without any of these instruments, the whole strategy could not be implemented in serbian laws and instructions for usage. expected results of these instruments are overall usage of renewable energy sources in serbia and mutual cooperation of all interest group in process (investors, stake holders, population, politicians, local government etc.) laws promotion of energy efficiency and usage of renewable energy sources can be exhilarate through enactment of new laws in the field of energy, environmental protection etc. in serbia, these are: - energy law ("official gazette of the rs ", n . / ) determines long term goals for development and stimulating measures for increasing energy efficiency - law on planning and construction ("official gazette of the rs ", n . / ): this law is not mentioning energy efficient buildings - law on environmental protection ("official gazette of the rs ", n . / ) - law on integrated environmental pollution prevention and control ("official gazette of the rs ", n . / ) - law on environmental impact assessment ("official gazette of the rs ", n . / ) - law on strategic environmental impact assessment ("official gazette of the rs ", n . / ). - laws on international investments, concessions etc. all of these legislative documents are functioning on internal level, without corresponding to each other. one of the main objectives in serbian legislative is the harmonization of laws and politics in order to make an implementation of res and energy efficiency in serbia easier and more operative. institutions there are several competent institutions in serbia in the area of energy efficiency and renewable energy sources: ministry of mining and energy of the republic of serbia; energy efficiency agency of the republic of serbia (seea); ministry of science, ministry of environmental protection – directorate for the environmental protection; ministry of energy and mining, ministry of finance; ministry of infrastructures; ministry of economy and regional development; republic development bureau; republic statistical office; national information technology and internet agency; recycling agency; energetics agency; republic agency for spatial planning; serbian land s p a t i u m http://www.seea.sr.gov.yu/downloads/zakonoenergeticiengleski.pdf http://www.mfin.sr.gov.yu/ http://www.mugrs.sr.gov.yu/ http://www.mpriv.sr.gov.yu/ http://www.mpriv.sr.gov.yu/ http://www.razvoj.sr.gov.yu/english/index.htm http://www.razvoj.sr.gov.yu/english/index.htm http://www.statserb.sr.gov.yu/ http://www.arii.sr.gov.yu/?lang=en http://www.arii.sr.gov.yu/?lang=en development agency; belgrade land development public agency; the european agency for reconstruction, eps, nis etc, innovation centers, technological parks, etc, research institutions qualified for development of energy efficient buildings and settlements, public agencies, public utility companies; local governments and communities, city managers and city architects. main goal is to harmonize working, objectives and strategies of these institutions, because it is the only way to implement „energetics development strategy until “. these are the basic interest groups in process of implementation of renewable energy sources in serbia. energy efficiency agency of the republic of serbia (seea) taking into consideration the current state within energy efficiency issue and renewable energy sources, energy policy objectives, as well as the contemporary practice in european countries, ministry of energy and mining of the republic of serbia recognized the need for national agency. therefore, according to energy law, adopted on august , and with the financial support of the european agency for reconstruction, it has been re- established and thus operating for the period of two years as a separate republic organization. energy efficiency agency of the republic of serbia (seea) was formed by new energy law. energy efficiency agency is formed as a special republic organization meaning separate legal entity. serbian energy efficiency agency executes the tasks envisaged by the energy law, as an integral part of the overall energy policy, led by the ministry of energy and mining of the republic of serbia. the managing of the agency is carried out by director who is appointed by the government of the republic of serbia. internal organization and job description in the agency is approved by the government. agency's mission is to improve the usage of renewable energy sources. agency implements its mission through sector, multi year programs for energy efficiency improvements and promotion of renewable energy sources. all programs are funded by european union's donation, through european agency for reconstruction. agency also organized a number of educational programs for local self governments, professional experts from industry, then energy engineers, energy management and business plans, thus aiding institutional capacity building in serbia. agency for energetics energetics agency is the most important newly formed institution in the field of energetics. it is planned to maintain licenses issuing for the facilitation of energy subjects, define the methodology for the calculation of cost justification, define rate systems for the regulation of energy systems, and approve price policies of energy subjects whose functioning it regulates. by ratifying the „energetics development strategy until “ and foundation of the energetics agency, the ministry of energy and mining rounded the legislative activities in the application of energy sector reforms. energy communities of south-east europe, athens signing the athens memo in . and ., serbia integrated into the regional energy market of the south east europe. the meeting of the european union ministers was held on the december . and the basic principles of the energy community contract were established on that occasion. programs and implementation in serbia programs „energetics development strategy until .“ proposes several specific programs: energy efficiency, new and renewable energy sources, environment protection, scientific, research and technological progress, aimed education and expert education in new and existing activities in the sector, including the implementation of contemporary statistics system, and additional energy regulations for the energy activities in new conditions, both locally and in the region. if this strategy would be properly carried into effect, the results in serbia will be notable in every household, residential and business building. strategic programs of the agency for energy efficiency • coordination of national policies with trends of energy efficiency • energy efficiency in building design • energy efficiency in communal energy • energy efficiency in industrial environments • energy efficiency in transport • renewable energy sources (r.e.s.) • co-generation of heat and electricity program realization of program (a) is, through “energy efficiency in serbia” project, helped by the “world bank”, with $ million. this project consists of three components: (a) clinical center of serbia - reconstruction, (b) school, hospital and other buildings of public interest - reconstruction for the improvement of the energy efficiency, and (c) technical help offered to the agency concerning the realization of this project. national energy efficiency program (neep) ministry of environmental protection – directorate for the environmental protection of the republic of serbia unified the research, development and engineering activities and potentials of serbia under the “national energy efficiency program” (neep). the goal of this action was to raise the efficiency of the production, distribution and usage of all means of energy and energy sources. some building energy efficiency projects and programs it is important to mention when the development of energy efficiency is concerned the “energy revitalization and comfort optimization” for schools and kindergartens in belgrade, the project invested by the education secretary of the belgrade city assembly. for a number of years, serbia’s standard u.j . had been neglected. higher project s p a t i u m http://www.ear.eu.int/ http://www.ear.eu.int/ http://www.seea.sr.gov.yu/downloads/zakonoenergeticiengleski.pdf temperatures are recommended, which would lead to significant increase in efficiency with long distance heating. summer temperatures and humidity are established as parameters relevant to summer climate. data, acquired by the republic hydro-meteorological institution, are based on daily averages. research should be continued, based on the hourly values. conclusion with the application of principles of energy efficiency in planning and design, need for conventional energy sources, which are not renewable, and represent high pollution potential, is lowered. sustainable urban planning, from the aspect of rational energy consumption, is an important task of planers, engineers in energetics and architects. this is why the concept of energy distribution should be based on the integration of urban planning and energy consumption planning. one of the key points is the connection between policies concerning sustainable development and the ones concerning the exploitation of renewable energy sources. application of mainly neglected, renewable energy sources, for which there is a high potential in serbia, but are not researched and technologically improved, is one of the solutions which strives towards the preservation of remaining resources and the environment. apart from that, one of the broader goals of the renewable energy sources is the poverty minimization. the value of r.e.s. lies in its ability to adequately respond to all challenges of the energy sector: energy distribution safety, economic growth, sustainable development and ecological plausibility. insistence on energy as public good with long term effects on the environment must have an appropriate legislative base, as well as actualization instruments, with adequate stimulations through tax and other incentives. all this is to build awareness for the need for rationalization and usage of the renewable energy sources. this is why an additional attention should be paid to education, legislative and regulation systems. these systems should constantly adapt to the technological progress of the public. in order to meet these goals, a joint action of energy suppliers, republic and local government and end users should be developed and maintained. republic of serbia has not yet taken any serious actions in the path of preserving its resources. this is the reason for the assembly through it's ministries to research the options and set the policies concerning the subject in that direction. knowledge on possible effects of climate changes on the application of long term development goals and poverty limitation, as well as the strategic goal of serbia to participate in european integration processes as an active member in solving the problems of mentioned climate changes, were reasons for the creation of the adequate strategy with it’s measures action plan. this facilitates the support on the creation and realization of the national policy and measures concerning climate changes, and compliance to obligations from the un convention on the climate changes and kyoto protocol. based on all that is said, it is safe to assume that cities of serbia are ready for the application of program and implementation of principles of sustainable planning and rational energy consumption. with this, it is possible to significantly lower the amount of traditional energy sources, and their impact on the environment. concerning the fact that the large part of energy and ecology problems represents an issue with global character, overcoming this problem is of great importance for the further integration of serbia into international community. s p a t i u m references achard p, gicquel r ( ) european passive solar handbook, commission of the european communities, brussels. agenda , united nations conference on environment (unced), rio de janeiro, . a "grant night out" for sustainable energy ( ), energy globe awards , renewable energy world, (rew), james & james may-june, , vol , no , pp. - . baumgartner r., zielowski, c. ( ), analyzing zero emission strategies regarding impact on organizational culture and contribution to sustainable development, journal of cleaner production ( ), pp. - ditz a, martin h ( ) energie und stadtplannung, erich schmidt verlag, berlin. ecotech ( ) sustainable architecture today, issuse , london. „energetics development strategy until .“, ratified on may th ., ministry of mining and energy of the republic of serbia egger, c. oehlinger and g. dell, making things happen! regional action plans for renewables, rew, vol. , no. , pp. - . gaudiosi g ( ): energy and environment, renewable energy, , pp. - . group of authors ( ): “development of a framework strategy for serbia and montenegro climatic changes and action plan for addressing the problem of gas emissions accompanied by the greenhouse effect”, regional environmental centre for central and eastern europe (rec), belgrade group of authors ( ): monograph :”investigations of rationalization and substitution of energy by new and renewable energy sources”, project t. , siv, belgrade hanreich, g: sustainable and secure, towards a european strategy for energy supply ( ), rew, may-june, , pp. - . hein, k. ( ), future energy supply in europe – chalenge and chances, fuel ( ), pp. - jager-waldau, a. ( ), photovoltaics and renewable energies in europe, renewable & sustainable energy reviews ( ), pp. - kaya, d. ( ), renewable energy policies in turkey, renewable & sustainable energy reviews ( ), pp. - koch, h.j. ( ) :the value of renewables, rew, nov-dec, pp.. - . los s, pulitzer n ( ): l'architettura del regionalismo, guida alla progettazione bioclimatica nel trentino. trento official web site of serbian energy efficiency agency, www.seea.sr.gov.yu pugliese, m., cameron, j., wilder, m. ( ): from kyoto to bonn, implication and opportunities for renewable energy, rew, sept-oct. , pp. - . pucar, m. pajević, m., m. jovanović ( ): monograph: "the bioclimatic planning and designing – urban design parameters". the monograph, zavet, belgrade pucar, m ( ): "renewable energy sources and the sustainable development". a chapter in the monograph: the use of resources, sustainable development and spatial arrangement. book , published by iaus, pp. - . pucar, m. ( ): "a rational energy consumption and the use of renewable energy sources as a precondition for a sustainable development of settlements in serbia", scientific-professional conference: principles and practice of sustainability in the development of settlements in serbia, society of urban planners of serbia, kosjeric, pp. - . pucar, m. ( ): the use of local energy sources - a precondition of regional development, the national scientific conference, regionalization of serbia and montenegro – a road to european integration processes, uus, kragujevac, pp. - . pucar, m. ( ): international and domestic experiences in planning and application of the renewable energy sources". a chapter in the monograph: a contribution to advancing the theory and practice of planning and implementation, published by iaus, pp. - . pucar, m. ( ): "energy efficiency in urban planning and design”, faculty of civil engineering, belgrade, pp. - . pucar, m. ( ): sustainable city planning and impact of energy consumption in buildings on climatic changes, monograph :sustainable development of cities, iaus, belgrade, pp. - . pugliese, m., cameron, v. and wilder m. ( ): from kyoto to bonn, implication and opportunities for renewable energy, rew, vol. , no. . p. . schittich ch, ed. ( ) solar architecture, edition detail - institute für internationale architektur-dokumentation gmbh & co. kg münchen, birkhäuser – publishers for architecture, basel, boston, berlin sims, r. ( ): united nations - preparing to examine energy and sustainable development, rew, july-august, pp. - . “strategy of local sustainable development”, belgrade, . may . turner, g. ( ): climate change a glance in the rearview mirror, and at the road ahead, rew, nov-dec , vol. , no , pp. - . walker, g., devine-wright, p. ( ), community renewable energy: what should it mean?, energy policy-in press ( ), pp. . wines j. ( ) green architecture, benedikt taschen verlag gmbh, hohenzollernring , d- , keln. word sustainable energy day, wels, austria, march, . s p a t i u m http://www.seea.sr.gov.yu/ southern journal of agricultural economics july, a look at major events impacting productivity and uncertainty in southern agriculture during the 's robert w. rudd in view of the breadth of the topic, coverage the climate shift issue achieved a significant is limited to identifying the events and cor- degree of public awareness in the wake of two menting on the types of impacts on agriculture phenomenally cold winters, and . rather than stating specific empirical esti- the subject of the controversy was the projec- mates of impacts. numerous researchers in tion of long-run dramatic changes in climatic agricultural economics have examined the conditions on a global scale. though climatolo- quantitative dimensions of impact from parti- gical experts disagree on both cause and direc- cular scenarios of future courses of some of the tion of the temperature change, all agree that a events identified here. few degrees' change in average temperatures with only one or two notable exceptions, the worldwide in either direction would portend current commodity output mix of southern total calamity. it is encouraging that a majori- agriculture is similar to that for u.s. agricul- ty of the climatologists recently questioned on ture as a whole. ranking the top eight farm en- this point by the national defense university terprises of the south in dollar value ( ) foresaw only a slight warming trend-not to shows tobacco in the southern region replacing exceed / degree celsius by the end of the cen- wheat in the national ranking; dairy, corn, and tury [ ]. the absence of a clear consensus for hogs are more important nationally and broil- radical change in climate leads to the conclu- ers and eggs are more important in the south- sion that the net effect of the climate issue on ern complex. therefore, if those dimensions of agriculture is a slight increase in uncertainty agriculture associated with geographic loca- for the normal farm planning cycles. tion, such as population, climate, or transport among the events of the s which affect net, are excluded, the major events affecting agriculture, four major changes in the econom- southern agriculture in the s can be dis- ic environment of agriculture are worthy of cussed in terms of u.s. agriculture. comment: ( ) the growth of interdependency in international trade and associated develop- transitory events: food crisis ments, ( ) domestic inflation and its conse- and climate shifts quences, ( ) the energy crisis, and ( ) environ- mental regulation. two events during the s, the food crisis and the climate shift issue, seemed at the time of their occurrence to be major events in terms of their potential impacts on agriculture. the interdependency in later turned out to be transitory. international trade the significance of the food crisis of the early s, with record high prices for u.s. farmers, the shift to a substantially greater involve- ranked substantially higher in middecade than ment and interdependency of agriculture in in- it does today. a similar comment could be ternational trade during the s is perhaps made about the earlier sensing of potential the most far-reaching event of the decade. at world food shortage to be found in administra- the turn of the s, u.s. agricultural exports tion pronouncements of the - period. were valued at about $ . billion annually, and the food crisis of - was not an event had not changed significantly in value since which in itself had lasting effects on producti- the mid- s. imports of farm products at vity, although it may have changed some ele- $ . billion left agriculture's net contribution ments of uncertainty through shifts in price to the balance of payments at just over $ and/or income expectations of producers, and billion, well below the peak contribution for the heightened public awareness of the possibili- s of $ . billion in . dramatic growth ties of recurrence. has occurred during the s in volume and robert w. rudd is professor and chairman, department of agricultural economics, university of kentucky. journal paper no. - - , kentucky agricultural experiment station. the author acknowledges the helpful suggestions and comments of kurt anschel, angelos pagoulatos, eldon smith, alan randall, and larry jones. errors and omissions remaining are those of the author. value of u.s. exports of agricultural products ter food prices from external influence may to an estimated $ . billion in , with a net modify these conclusions somewhat, the insta- contribution of about $ billion to the balance bility suggested may well be a continuing eco- of payments. this growth has exceeded the nomic risk factor for southern as well as u.s. rate of growth of u.s. production of farm pro- agriculture, causing greater price variability in ducts. the share of dependence of u.s. agricul- farm products. ture on international markets has grown from carter and johnston [ ] identified another about percent to more than percent last feature of the interdependence of u.s. agricul- year. ture in the world economy which bears upon all recognize the important benefits of this agriculture's price stability. they observed gain in agricultural trade for the u.s. economy that many of the united states' international because of the substantial and growing nation- trading partners place greater reliance than al dependence on petroleum imports. however, this nation does on some form of government this foreign trade also increases the vulnerabil- intervention or participation in a trading bloc. ity of domestic markets for farm products to thus, u.s. efforts at nondiscriminatory reduc- the variability in international markets. u.s. tion of trade barriers, which are important to market price experience with wheat, corn, and u.s. agriculture, are viewed differently soybeans earlier in the s adequately illu- depending on the individual country's or trad- strates this risk. ing bloc's economic and political goals. as a the impressive growth of u.s. agriculture's consequence, the u.s. may be less successful in export markets occurred during a period when negotiating reductions in trade barriers, the ef- the united states made a change in monetary fects of which are conceded to be destabilizing. policy which carried significant consequences hence, the interdependence which has brought for international trade. after years of retaining the positive benefits of greater trade in farm the policy of fixed exchange rates with the dol- products internationally carries the potential lar tied to gold, the united states moved early for greater price and income instability. in the s to a system of floating exchange rates with other currencies. schuh [ ] analyzed the consequences of this changed role inflation of foreign exchange rates and the increased in- ternational mobility of capital. he finds that the domestic economic environment for agri- these two features cause the consequences of culture during the s featured one easily changes in government fiscal and monetary agreed-upon "major event" - inflation. after policy to be channelled primarily into export the decades of the s and s during sectors, such as agriculture. which inflation averaged less than . percent the application of schuh's analysis shows annually, as measured by the cpi, the rate of agriculture in the early s to have been in increase in the general level of prices climbed an economic squeeze; the over-valued currency to nearly percent in and just over served as an implicit export tax and the gov- percent for . food prices, with a similar ernment resorted to monetary and fiscal poli- history of very modest increases in the s cies to stem gold outflow and raise interest and s, rose an astonishing percent in rates. more recently, the precipitous decline in and equaled the cpi climb for . after the value of the dollar has undoubtedly worked declining to less than percent in , the to u.s. agriculture's short-run advantage in in- rate of inflation resumed its upward climb and ternational trade. today many view the dollar approximates percent as measured by the as undervalued, and consequently functioning cpi for . food prices have followed direc- as an implicit export subsidy, giving rise to tionally and seem likely to have increased by extra strength in agricultural export markets. nearly percent in . record farm prices however, when the dollar recovers its equilibri- achieved during - , though associated um, a substantial adjustment will be forced with reduced agricultural production abroad upon u.s. agriculture, due to a number of climatic aberrations world- schuh concludes that, "in the future we can wide as well as an upheaval in international expect to have an unstable demand for agricul- currency exchanges, created a lasting tural output in marked contrast to the past, impression in the minds of many people in with the source of that instability coming from farming. in effect, a new level of price expecta- the foreign sector, even though those fluctua- tions was established, a level which, regardless tions of foreign demand are an indirect conse- of its original cause, may have played some quence of domestic monetary and fiscal part in the agricultural activism and resur- policy" [ , p. ]. gence of the parity concept in the thinking of though changes in international trade barri- the members of some agricultural groups, such ers and other impediments to trade as well as as the american agricultural movement, in changes in domestic agricultural policy to shel- the late s. the consequences for agriculture of a period the energy crisis of inflation depend on the specific circum- stances. if farm prices keep up with the rate of the event which in some ways provided the inflation, the price impact may be minimal, greatest shock to the u.s. economy in the particularly if agricultural productivity s was the energy crisis-the exposure to growth offsets greater rates of gain in prices of the scarcity of a common consumer good. the production items farmers must buy. the background of the energy crisis is well known: evidence on this point is somewhat mixed. the decline in new discoveries of petroleum and tweeten and griffen [ ], in a study of price natural gas, the increased demand for energy, experience in the years - , conclude that the regulation of air pollution practices, and national inflation does have the effect of re- the opec embargo with its aftermath of rapid- ducing real prices in the farming industry, and ly rising energy prices. reduces the parity ratio. gardner [ ], examin- ing a more recent but shorter time span, - in subte of thes developments, which por- , and using monthly data, found that both tend substantially reduced fuel availability in farm product and farm input prices respond the future, the reaction in terms of changes in quickly to changes in the general price level nput costs was rather modest through . a gardner's analyses also suggest that, on the sharp cl in e mid in fertilizer costs basis of - , both net income and farm as- occurard in te mid- t s in association with set values have grown in real terms during natl gas limitations, but these costs have periods of inflation. such conclusions do not re- since declined. tougy fane fuel costs have spond to the question of effects of inflation risen substantially since thebeginning of thespond to the question of effects of inflation s, the increase in costs of fuels and energy during a period of rising real farm costs due to , the rise in costs of f a resource scarcities; these effects are likely to be e otr s n the ar r tn com- unfavorable to agricultural producers. further, e er e the farm production com- the uncertainty over interest rates and the plex. clearly, the federal government's problems of intergenerational transfer of farm- controls on petroleum and natural gs prices have held this cost increase in check. fuel anding operations, as well as cash flow difficulties he he this ct rese in check. fuel and and risks with low equity land transfers in the energy costs, which represent about percent face of inflated asset values, are readily ap- of the total costs of farm production, will begin parent. as gardner concludes, the overall re- to rse more rapidly in the wake of such de- sult of inflation is an extraordinary element of velopments as the recent opec decision to raise oil prices and the governmental decision risk for agricultural pr . to partially decontrol energy prices domestic- ally. one may speculate also on the effects of in- flation on productivity via the limitations the energy crisis has spawned a variety of which its continuation may create. for studies examining the consequences of alter- example, insofar as inflation continues to fuel nate scenarios with respect to energy avail- the rise in the price of farmland (the perfect in- ability and pricing, ranging from reversion to flation hedge), it may also severely limit the on-farm sources of power to the consequences growth of the family farm size as usually con- of technological breakthrough by development ceived. this point is difficult to deny because of plants as oil sources [ ]. van arsdall and average asset values per farm exceed a quarter devlin [ ] project an increase of percent million dollars today for more than one of the in real energy prices to farmers between states of the region. and with no energy legislation, and a percent increase with the president's national carter and johnston [ , p. ], surveying energy plan (may version). an unpub- the factors which have caused rapidly rising lished study for resources for the future [ ] land values in the s, identified the rising used the nirap model to project energy use commodity price expectations, persistent infla- and impacts on a national basis for the years tion in the general economy, and the conse- , , and . quences of international market interdepen- clearly, for at least the next decade or so the dence as contributing factors. they also note energy situation will be cost-increasing for increased difficulties of entry and the problem american agriculture and may affect capital of intergenerational transfer. their observa- outlay, production practices, and nonpetroleum tions suggest the possibility of increasin risks input availability to the detriment of produc- in farming as the pressures mount for greater tivity levels and with increasing risks. the dependence on capital markets and larger direction of change, as real energy costs rise, farms rather than the family farm as the typi- will be toward substitution of land, labor, and cal unit, a unit which has shown greater capa- capital inputs for energy in the product mix of cities to absorb and adapt to risk. farming. environmental restrictions amounts and constituency of effluent dis- charge. in agriculture, feedlots would be a pri- linked closely to the limitations on avail- mary target depending on the applicable ability and use of energy in agriculture are definitions of size and scope. a second objec- several regulatory restraints related to the en- tive of this act is to control agricultural non- vironment that were enacted during the s point sources of water pollution. the goal is [ ]. each of these enactments embodies, in dif- elimination of pollution in navigable waters by ferent aspects, a broad concern with which . such goals could affect agriculture in everyone can agree, i.e., it is worthwhile to pre- terms of cultivation practices, nitrogen fertiliz- serve and improve the environment and to pro- er restriction, and restrictions on uses of herbi- tect people's health with necessary safety mea- cides. hurt and reinschmiedt [ ] indicate a sures. however, each of these pieces of legis- severe economic impact on southern agricul- lation involves costs to achieve its ends and ture if nonpoint pollution goals are met. under the costs are not uniform in their impact. this act, the primary authority for manage- the national environmental policy act was ment lies with the states, but the epa retains passed into law january , . it established authority to impose more stringent require- the federal government's intent to protect the ments. the real question with this act is how natural environment and to take positive extensive restrictions will be. though it may steps to improve it. it resulted in the creation not be an expression of epa intent, a recent of the environmental protection agency, study under epa sponsorship examined, which consolidated into one agency all the among other things, of such possibilities as ( ) federal programs for air pollution, water pollu- a complete ban on the use of all insecticides, [ ] tion, solid waste disposal, pesticides regula- restriction of fertilizer application to tion, and environmental radiation. pounds per acre, and ( ) elimination of straight among the acts which the epa administers row cultivation [ ]. is the federal environmental pesticides con- the clean air act amendments of are trol act of [ , p. ]. the pesticide also of interest to agriculture. this act, too, is control act basically strengthened the author- administered by epa, and one of its concerns ity of the federal insecticide, fungicide, and is the prevention of crop damage due to high rodenticide act of , and moved from only levels of photo-oxidants in the atmosphere. an regulating the labeling of such products to the indication of the importance of this develop- authority for the restriction of use of the pro- ment is evident in the epa estimates for ducts. the activities of epa in the pesticide of crop losses nationally due to high oxidant area resulted in bans on the use of ddt, aldrin, levels, which are as high as $ billion [ , p. ]. dieldrin, mirex, and others [ , p. ]. though the finally, the occupational safety and health constraints represented by restricting act of , known as osha, has been an irri- pesticide use have undoubtedly created some tant to the commercial farming population. hardships for agriculture, it is difficult to esti- the goal of the act is the elimination of hazards mate the full effect of such withdrawals on to safety and health occurring in a work situa- agricultural productivity. the pattern of build- tion. osha, the agency of the department of up of resistance in insects to these chemicals labor established for the administration of had already been observed and had occasioned this act, has levied numerous requirements, shifts from chemical to chemical in an attempt ranging from requiring roll bars on tractors to find a more effective means of insect control and sanitary facilities for workers to re-entry in the face of growing immune reactions. standards for workers engaged in the applica- on the positive side, these epa efforts at tion of agricultural chemicals. regulation have resulted in the development of most of the provisions of environmental leg- a program known as integrated pest manage- islation are of concern to agriculture because ment [ , p. ] which maximizes the natural of the potential for restrictive regulations [ ]. control of pest populations through knowledge the environmental legislation affecting agri- of each pest, its environment, and its natural culture involves, to an important degree, enemies. indications are that this approach giving a public agency the responsibility of often provides better pest control at a lower preparing specific guidelines for the accomp- cost and with fewer environmental problems lishment of overall worthwhile objectives. than reliance on chemical pesticides alone. many of the improvements that are possible the federal water control act amendment under these acts will be limited very clearly by of aims at strengthening the clean water the tradeoffs between environmental ends and program by regulating both point and non- the competing end of energy use conservation point water pollution [ , pp. - ]. the act [ ]. in summary, these environmental acts is administered by epa and involves the regu- represent sources of irritation and potential for lation of point source discharge of effluents by reduction in efficiency in agriculture as well as requiring permits which specify the allowable some elements of uncertainty as to whether specific practices will be acceptable. they will and has expanded the land base adaptable to add to the feeling of producers in agriculture row crops (for indications of productivity im- that they are over-regulated and over- pacts of some emerging agricultural technolo- constrained in ways that are less than appro- gy, see [ ] ). priate for the ends sought. conclusions other events the major economic events delineated here other events of the s that are signifi- seem to have impact on uncertainty in agricul- cant to agriculture in terms of potential effects ture than on productivity. further, they tend on productivity and uncertainty are the re- to support the conclusion that agriculture's in- sumption of diplomatic and trade relations be- creased uncertainty is predominantly in the tween the u.s. and the people's republic of marketplace, as international developments china, the changed patterns of migration to ru- become ever more important in determining ral nonfarm areas, the modifications of inheri- price for an increasing share of u.s. agricul- tance tax laws affecting family farms, and the tural output. developments and decisions wave of consumer activism which appeared in among the opec nations combined with legis- the s. lative and administrative judgments at home though most estimates of overall productivi- increasingly jeopardize that part of the tech- ty change for agriculture indicate a slowing in nological progress of agriculture which is the rate of growth of productivity [ ], one must based on cheap fossil fuel. inflation threatens not overlook the specific developments in the to disrupt agriculture's structure as well as in- s in the physical and biological sciences af- crease the uncertainty of its cost and price en- fecting agriculture. some examples follow.' vironment. and environmental legislation, on agricultural engineers cite the commercial balance, has tended to increase the uncertainty development of a pasture renovator for inter- of the cost complex of agriculture and the con- seeding legumes into grass with a single ma- tinuance of some production practices which chine operation that will permit the efficient may be barred by environmental restrictions management and utilization of approximately at some future date. one-half of the u.s. farmland which should or these events challenge agricultural must remain in grass. this machine will allow economists to provide useful insights upon an increase in productivity of that land by a which producers can base decisions in this in- factor estimated to be about . animal scien- creasingly uncertain economic environment. tists have identified selenium as an essential with sophisticated analytical methods facili- element in animal nutrition and it has marked- tated by computers, agricultural economists ly reduced disease losses in cattle, hogs, sheep, can simulate potential outcomes from regional turkeys, and poultry. the success of the hog and national models under a range of different cholera eradication program nationally has re- scenarios. as always, success in this effort will duced the cost of pork production significantly depend upon the relevance of the alternatives through reduced death losses and costs of vac- identified and the effectiveness of the informa- cination. agronomists point out that the popu- tion delivery systems. larization in the s of minimum tillage finally, even with the help of agricultural practices originating in the s has material- economists, designers of public policy must ly improved agriculture's ability to cope with call forth their best efforts to solve the prob- reduced fuel availability in the years ahead, lems generated by the events of the s. references [ ] carter, harold o. and warren e. johnston. "some forces affecting the changing structure, organization and control of american agricluture," american journal of agricultural economics, volume , december , pp. - . [ ] council on environmental quality. environmental quality, second annual report of the council on environmental quality, september . [ ] council on environmental quality. environmental quality, fourth annual report of the council on environmental quality, september . [ ] council on environmental quality. environmental quality, sixth annual report of the coun- cil on environmental quality, december . 'the author is indebted to john walker, chairman, department of agricultural engineering, virgil hays, chairman, department of animal sciences, and a. j. hiatt, chairman, department of agronomy, university of kentucky for these examples. [ ] gardner, bruce, "inflation and agriculture," statement presented at national outlook con- ference, washington, d. c., november , . [ ] hurt, verner and lynn l. reinschmiedt. "non-point source of pollution abatement-po- tential impact and research needs," draft of paper to be presented at southern agricul- tural economics association meetings, new orleans, february , . [ ] irwin, george d. and j. b. penn. "energy, government policies and the structure of the food and fiber system," american journal of agricultural economics, volume , de- cember , pp. - . [ ] lu, yao-chi, leroy quance, and chun-lan liu. "projecting agricultural productivity and its economic impact," american journal of agricultural economics, volume , december , pp. - . [ ] national defense university. "climate change to the year ," ft. leslie j. mcnair, washington, d. c., p. xvii-xix. [ ] pagoulatos, angelos and john timmons. "alternative scenarios of energy use in u. s. crop production," southern journal of agricultural economics, volume , december , pp. - . [ ] schuh, g. edward. "income and stability implications of monetary, fiscal, trade and eco- nomic control policies," farm and food policy symposium, great plains agricultural council publication no. , pp. - . [ ] skold, melvin d. and j. b. penn. "production potentials in u. s. agriculture in looking for- ward: research issues facing agriculture and rural america," ers, usda, september , p. . [ ] taylor, c. robert and klaus k. frohberg. "the welfare effects of erosion controls, banning pesticides, and limiting fertilizer application in the corn belt," american journal of agricultural economics, volume , february , pp. - . [ ] tweeten, luther and steve griffen. "general inflation and the farming economy," research report, oklahoma agricultural experiment station, march , p. . [ ] u. s. department of agriculture. food and agriculture, draft report, ers, february . [ ] van arsdall, thomas and patricia j. devlin. "energy policies: price impacts on the u. s. food system," agricultural economics report no. , escs, usda. international journal of management sciences and business research, april- issn ( - ) vol- , issue international journal of management sciences and business research, april- issn ( - ) vol- , issue http://www.ijmsbr.com page an analytical over view of bank loans extended to smes in pakistan author’s details: ( ) dr munawwar kartio-vp & area manager askari bank limited sukkur ( ) prof dr albeena mirza -department of economics university of sindh jamshoro ( ) farhan zeb khaskhelly-lecturer iba university of sindh jamshoro abstract small and medium enterprises are the back bone of economy and are considered to be locomotive for the economic development for the developed as under developed economies. in the present economic scenario no one can ignore the importance and role played by smes in the overall rise of standard of life, reduction in poverty, provision of employment, foreign exchange earnings and gdp growth. economy of pakistan has substantial potential for the growth of this segment but unfortunately desired benefits could not be obtained for variety of reasons including political instability ,continuity in economic priorities and policies ,law and order situation prevailing in the country ,lack of infra-structure ,energy crisis ,most important hurdle is access to bank lending at concessional rates. the central bank of the country with collaboration of smeda is playing an important role to make bank finance available which is as important for smes as oxygen for human body but so far desired results could not be achieved in true sense as banks are shy to allow lending facilities, most importantly due to lack of collateral to cover the risk. sbp reports revealed that cash flow based lending is discouraged instead collateral based lending is focused. bank lending allowed to sme sector comprises around % of total finance allowed to private sector ,out of which major portion is extended within the limit of . million and only % of total sme finance is extended as clean loan. key words: sme, bank loans, sbp, pakistan introduction: definition of sme sme is a term used for business sector which falls in the category of small office –home office size and large enterprise. smes are broadly defined on the basis of number of employees’ engaged, capital invested and business turn over. in developing countries small business means having numbers of employees and medium size business having more than and not more than number of employees. but authorities in pakistan have not a single definition for smes. smeda (small and medium development authority) defines it on the basis of earning (productive) assets and the number of employees engaged in economic activity. according to smeda it is an enterprise which does not engage more than employees and its annual business turnover is not more than million in pkr terms. the central bank of the country in its prudential regulations (prs) defines smes as it is ideally not a public limited company and does not engage more than employees. however it has further divided in sectors as under, parameter /industry trading manufacturing services no of employees total assets total sales turnover assets are earning assets excluding land, building and plant state bank of pakistan has revised its prudential regulations and defined the segment by separating the se (small enterprise) and me (medium enterprise).accordingly se is defined as under small enterprise no of employees annual sales turnover up to (including contract employees) up to m http://www.ijmsbr.com/ international journal of management sciences and business research, april- issn ( - ) vol- , issue http://www.ijmsbr.com page medium enterprise no of employees annual sales turnover - (manufacturing & service mes) - (trading mes) (including contract employees) above rs million and up to rs million (all types of medium enterprises) united states of america (usa) in united states of america small business act defines small business is a concern that is independently owned, operated and is not dominant in its field of operations with fewer than employees. united kingdom (u.k.) in uk small business is an entity having annual business turnover not more than £ . million and have not engaged more than employees and medium sized entity is an enterprise having annual business turnover of not more than £ . million with maximum number of employees and a balance sheet total of not more than £ . million as defined in sections and of the companies act . european union (eu) in european union sme is classified in three different categories; micro, small and medium-size. the category of micro, small and medium-sized enterprises (smes) is made up of enterprises which can engage fewer than employees and have annual business turnover up to million euro, and/or balance sheet total not exceeds million euro. in case of small enterprises enterprise can engage fewer than persons with annual businesses turnover or balance sheet total should not exceed million euro whereas micro unit is one which can employ up to employees with annual business or annual balance sheet total which should be within the limits of million euro” broad industy groups of smes . manufacturing: the enterprises engaged in the manufacture or production of goods eg. textile, chemicals, vehicles, beverages, medical and optical instruments, household and other personal goods, etc . trading (wholesale & retail): the enterprises engaged in the retail and wholesale trading of goods, including their repair and maintenance. . services: the enterprises engaged in providing or rendering of services and include, though not restricted to, transport, communication, hotels, education, health and social work. significance of smes • since overhead cost of employees is lower than the larger firms hence it provides low cost employees with greater employment opportunities • it is a good source of export earnings due to low-cost labor is engaged in producing export goods. hence supports in balance of trade of the country. • it is a linkage between rural industrialization and most planned urban sector hence boost and assists in local and regional development. • it is helpful to achieve equitable and fair distribution of wealth http://www.ijmsbr.com/ international journal of management sciences and business research, april- issn ( - ) vol- , issue http://www.ijmsbr.com page • since smes are engaged to use indigenous/local produced raw material hence have positive impact on balance of trade. • it inculcates an environment of entrepreneurial and self-reliant culture by combining capital and skills together kills through a variety of lending techniques and skill development schemes. challenges faced by smes in pakistan lack of proper infrastructure: poor roads and transportation system, energy crisis, lack of industrial space at concessional rates and unstable prices mechanism badly affects the growth with stability of the economy in general and sme in particular. lack of marketing facilities: smes do not allocate sufficient funds for marketing rather depends on sales through sales staff which is also a barrier in creating brand and enhancing loyal customer base lack of information communication technologies: the importance of information is not realized in true sense by smes which is also a big hurdle in exploring new markets and on line marketing of products at competitive prices lack of access to finance: it is a major issue, entry and growth of new entity is very difficult without external resources. banks are shy to provide loans to sme for establishing new units as well as to existing units with mindset that the smes are not strong enough to bear the cyclical economic shocks and may commit default. poor educational system: smes are basically managed by one person or a group (mostly by family) does not possess a sound knowledge and skills of entrepreneurship hence may not be able to operate in a sophisticated manner. law & order issues: after / pakistan is in the state of war in terror hence it is quite difficult to enter and grow the business at desired pace as uncertainty prevails in the entire country. regulatory complexities: it is unfortunate that country on hand is facing terrorist activities on the other the cancer of corruption which has gripped entire system therefore smes are encountered with several difficulties in registration and compliance of laws which are only complied against out of packet payment. shortage of skilled manpower: the majority of work force is uneducated and unskilled which cannot meet the quality standards of modern era hence smes are compelled to engage unskilled manpower to carry on the operations. problem statement in pakistan major chunk of credit is taken by corporate sector and sme is second largest segment availing the finance. in pakistan there are more than million smes which constitute above percent of private sector enterprises in industrial sector provides around percent employment to non agriculture work force and contributed more than percent to gdp. despite that sme is facing major problem of access towards formal finance from banking industry. in this research study attempt have been made to explore the reasons as to why banking industry is reluctant to take exposure in smes and the issues which hinders bank lending in pakistan. specific objectives of study  an overview of sme sector in pakistan  to analyze the factors hindering the growth of sme  the factors responsible for poor access of bank lending http://www.ijmsbr.com/ international journal of management sciences and business research, april- issn ( - ) vol- , issue http://www.ijmsbr.com page  role of central bank to ensure proper share of loans to smes research methodology: the research is based on secondary data ,data was collected from data was collected from secondary sources; annual reports of commercial banks ,sbp publications ,latest available quarterly report on sme up to march was reviewed minutely. research papers, research journals, economic survey of pakistan, nbp economic bulletin, ibp quarterly journal to analyze and conclude the role of financial institutions played in extending loan facilities to sme sector. an attempt was made to analyze the loan allowed in percentage terms with overall loans extended to private sector and infected portfolio as well. more role of central bank was also reviewed in formulating policy guide loans to help out this most important segment and implementation thereof. review of literature smes play an important role in the development of world economies and are accepted as driving force for economic growth and development (sas aruwa, ). kashif, hamid and abaid ullah in explored that smes have performed as key player in the economic growth of world as they are able enough to manage and control the resources in a well-organized way for the uplift of society (hannah galvin). according to sherazi, iqbal, asif, rehman & shah smes in pakistan, are considered to be the life blood of economy as smes play an important role in economic development and is considered as a source of survival in worst economic circumstances ou & haynes, ; cook, have pin pointed the availability of finance as a key factor for successful operation of sme sector. wu, song, & zeng, has examined that financial needs for smes vary from initial sources such as owners’ equity ,their savings and retained earnings to formal outside funding inter alia include financial support from family and friends, trade credit (abouzeedan, ) ,angel financier , venture capitals (he & baker, ), chittenden, hall, & hutchinson, explored formal external funding sources by financial institutions and securities markets. according to the financial growth cycle paradigm proposed by berger and udell ( ) proposed financial needs of smes vary during the different phases of life cycle of the firm. challenges faced by sme in pakistan an overview of economy of pakistan; pakistan is at number six population wise; its population is around m .pakistan is agri based economy, it contributes more than one-fourth of output and two-fifths of employment. pakistan is producing enough food grain items to feed its population besides is third largest exporter of rice and is in big five major textile producing in the world. agriculture is now more than crops, within agriculture a significant change was witnessed. dairy, livestock, mutton, beef, poultry and other similar products is around % of total agriculture it is at third number in producing milk in the world. pakistan’s gdp growth gradually increased on year basis since . official numbers which do not portray true picture as major portion of economy is informal; unemployment is around to % underemployment remains on very high side. pakistan has somehow succeeded to restore its macroeconomic stability, pak rupee remained quite stable after heavy depreciation in near past. remittance from abroad is more than $ . billion per month which is major source of income. despite poor export performance, inflation remained under control and current account deficit was narrowed down, mostly due to downward trend in oil prices globally. pakistan and china has started implementation of cpec “china-pakistan economic corridor”, both countries agreed to invest $ billion on infrastructure and energy sector. contribution of sme towards economy of pakistan according to ifc , around . m businesses units are participating in economic activities to earn profit out of which around million are smes which means that more than percent share is contributed by sme http://www.ijmsbr.com/ international journal of management sciences and business research, april- issn ( - ) vol- , issue http://www.ijmsbr.com page shaving considerable contribution of percent to gdp and percent towards earnings of the country and providing employment to more than % of work force. in recognition of the contribution made by smes federal authorities and central bank in particular and all stake holders in general have taken bold steps to boost this important sector which include establishment of sme department in sbp ,sme bank ,issuance of separate prudential regulations for se & me and small and medium enterprises development authority (smeda).in spite of continuous efforts initiated by the stakeholders for the growth and development of this important segment desired goals could not be achieved as the sector is encountered with many challenges and problems as under, challenges faced by smes in pakistan lack of proper infrastructure: poor roads and transportation system, energy crisis, lack of industrial space at concessional rates and unstable prices mechanism badly affects the growth with stability of the economy in general and sme in particular. lack of marketing facilities: smes do not allocate sufficient funds for marketing rather depends on sales through sales staff which is also a barrier in creating brand and enhancing loyal customer base lack of information communication technologies: the importance of information is not realized in true sense by smes which is also a big hurdle in exploring new markets and on line marketing of products at competitive prices lack of access to finance: it is a major issue, entry and growth of new entity is very difficult without external resources. banks are shy to provide loans to sme for establishing new units as well as to existing units with mindset that the smes are not strong enough to bear the cyclical economic shocks and may commit default. poor educational system: smes are basically managed by one person or a group (mostly by family) does not possess a sound knowledge and skills of entrepreneurship hence may not be able to operate in a sophisticated manner. law & order issues: after / pakistan is in the state of war in terror hence it is quite difficult to enter and grow the business at desired pace as uncertainty prevails in the entire country. regulatory complexities: it is unfortunate that country on hand is facing terrorist activities on the other the cancer of corruption which has gripped entire system therefore smes are encountered with several difficulties in registration and compliance of laws which are only complied against out of packet payment. shortage of skilled manpower: the majority of work force is uneducated and unskilled which cannot meet the quality standards of modern era hence smes are compelled to engage unskilled manpower to carry on the operations. issues & challenges in sme financing banks are primarily reluctant to accept risk in this segment as according to them ratio of default is high at early as well as growth stage .the another issue is improper record keeping and maintenance of financial records. smes lack skilled staff to prepare their books and resultantly banks feels difficulty while accessing the genuine need of the business. besides the information pertaining to sme is unreliable. as smes cannot afford to offer adequate collateral and the financial institutions are unable to decide whether this sector possesses technical knowhow, marketing and managerial techniques that ensure the generation of desired cash flows for timely repayment of the loan. resultantly the process of financial intermediation breaks down for this important segment. the central issue is therefore lack of collateral though the smes have ideas to do start the business but have no tangible asset to offer for comfort of banks. moreover financial institutions perceive that smes are usually unable to overcome contingency shocks. http://www.ijmsbr.com/ international journal of management sciences and business research, april- issn ( - ) vol- , issue http://www.ijmsbr.com page role of sbp in growth of smes as discussed earlier the significance of smes, their contribution to gdp growth, creation of employment and earning of foreign exchange by boosting exports. keeping in view the same the central bank is actively engaged for growth and development of sme banking. sbp has taken several policy initiatives including issuance of separate set of prs for small & medium enterprise (se & me), implementation of smes supportive financing schemes such as credit guarantee scheme (cgs), refinance schemes for smes, pm youth scheme and capacity building programme. during last few years sme has been remained in focus for policy makers, state bank of pakistan is also paying focused attention for sme financing. the central bank has taken bold steps for the promotion of sme financing, which include,  establishment of separate division for sme  issuance of separate set of prs (prudential regulations) for se & me  establishment of help desk to support sme finance  formation of strategy for sme finance  developed concept paper on sme credit rating agency  concept paper on sme private equity fund. role played by banking sector for sme finance commercial banks of the country both nationalized as well as private are playing an encouraging role in providing financing facilities to the sme sector. despite several hurdles currently over a dozen of banks are actively participating in extending finance to sme, varieties of products have been tailored to boost the sector. the major contribution is made by five big (namely nbp, hbl, ubl, mcb and abl) which is around % share in bank lending and remaining % is allowed by all remaining banks including islamic banks. source: sbp the data analyzed and concluded that around % of private sector lending is allowed to smes, whereas smes constitute % of total business units and the number of smes availing upto june is which are around . % of total smes engaged in economic activities. moreover the share of finance to sme is majorly covered by domestic banks which constitute around . % and . % is contributed by public banks ,specialized banks share is around . %,islamic banks . % and remaining . %by dfi and foreign banks. sector wise composition of sme finance http://www.ijmsbr.com/ international journal of management sciences and business research, april- issn ( - ) vol- , issue http://www.ijmsbr.com page source: sbp the sector wise composition of sme finance depicts that trading sector has been provided % to trading, % manufacturing and % to services on average basis which means maximum focus is on trading activities. loan size-wise review: according to sbp loans up to rs million constitute around % of total sme finance which covers % of total borrowers around , borrowers, a large number of sme borrowers fall in this category with limit of . m .loans over rs. million with maximum limit of rs. million has % share of total sme finance while loans above rs. million with maximum limit of rs. million had a share of % and loans above rs. million had a share of percent. clean lending vs collateral based lending: while going through the various reports on sme finance it has been revealed that maximum % of total finance was allowed as clean loan which portray the mindset of bankers that they are reluctant to allow finance without any tangible assets despite the fact that sbp in their revised version of prs (prudential regulations) has allowed clean facility of million vide pr # (prs issued in may . conclusion: despite considerable contribution of smes in country’s economy and push from sbp bankers are still reluctant to allow cash flow based lending instead of collateral based lending. it is also disappointing that only . % of sme sector is provided lending facilities out of which majority falls in the category of loan amount below . m. maximum loan is allowed to trading sector. major portion of finance is provided by private banks which is around % .the loan amount is around percent of gdp which is quite negligible and it constitutes around % of private sector lending which is also alarming situation. recommendations: federal authorities should focus to provide business environment in the country by addressing highlighted issues in general and financing issues in particular. central bank although is primarily responsible for monetary policy of country, should allocate ceiling of credit limits for smes and inculcate culture of cash flow based lending to overcome the fear of sme loan default. the government of pakistan should make the loans available at concessional rates and defaulted loans should properly be compensated to banks. the challenges are going to be redoubled after cpec and wto hence steps should be taken to ensure uninterrupted supply of raw material to manufacturing sector without any abrupt price variation with control over energy crisis a major hurdle in manufacturing industry. financial institutions are required to expand outreach of sme financing to under privileged areas of the country. staff of banks should not only be well familiar with products meant for smes but also should be willing to serve. references services manufacturing trading sectorwise composition of finanace http://www.ijmsbr.com/ international journal of management sciences and business research, april- issn ( - ) vol- , issue http://www.ijmsbr.com page adb. ( ). private sector development strategy: promoting the private sector for growth and poverty reduction. manila: asian development bank, retrieved from www.adb.org/documents/policies/ private _sector/private. pdf on august . bari, & ali & haque, ( ). sme development in pakistan: analyzing the constraint on growth. pakistan resident mission working paper no . , islamabad: adb. beck, & thorsten, & asli & ross levine. ( .) sme, growth, and poverty: cross-country evidence, world bank policy research working paper , accessed from https://rru.worldbank.org/paperslinks/open.aspx?id= (on october ). . capacity building, nd oecd conference of ministers responsible for small and medium-sized enterprises, istanbul, turkey, ( – june, ) accessed from http://www.oecd.org/dataoecd/ / / .pdf (on september ). cerasela pirvu and laura giurca vasilescu and anca ( ), “banking financing for romanian smes- challenges and opportunities kashif hamid and abaidullah ( ), “financing the small and medium enterprises in faisalabad”. rehana kousar, anum durani, farheen zahra hussain and masood ul hasan ( ), “investigation of banker’s lending criteria to smes and assessment thereoff sas aruwa ( ), “financing options for small and medium scale enterprises in nigeria”.”. syed kamran sherazi, muhammad zubair iqbal, muhammad asif, kashif-ur-rehman and syed saad hussain shah ( ), “obstacles to small and medium enterprises in pakistan, principal component analysis approach”. http://www.ijmsbr.com/ wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ energy demand side management with supply constraints: game theoretic approach sciencedirect available online at www.sciencedirect.comavailable online at www.sciencedirect.com sciencedirect energy procedia ( ) – www.elsevier.com/locate/procedia - © the authors. published by elsevier ltd. peer-review under responsibility of the scientific committee of the th international symposium on district heating and cooling. the th international symposium on district heating and cooling assessing the feasibility of using the heat demand-outdoor temperature function for a long-term district heat demand forecast i. andrića,b,c*, a. pinaa, p. ferrãoa, j. fournierb., b. lacarrièrec, o. le correc ain+ center for innovation, technology and policy research - instituto superior técnico, av. rovisco pais , - lisbon, portugal bveolia recherche & innovation, avenue dreyfous daniel, limay, france cdépartement systèmes Énergétiques et environnement - imt atlantique, rue alfred kastler, nantes, france abstract district heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. these systems require high investments which are returned through the heat sales. due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. the main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand forecast. the district of alvalade, located in lisbon (portugal), was used as a case study. the district is consisted of buildings that vary in both construction period and typology. three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). to estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. the results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than % for all weather scenarios considered). however, after introducing renovation scenarios, the error value increased up to . % (depending on the weather and renovation scenarios combination considered). the value of slope coefficient increased on average within the range of . % up to % per decade, that corresponds to the decrease in the number of heating hours of - h during the heating season (depending on the combination of weather and renovation scenarios considered). on the other hand, function intercept increased for . - . % per decade (depending on the coupled scenarios). the values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. © the authors. published by elsevier ltd. peer-review under responsibility of the scientific committee of the th international symposium on district heating and cooling. keywords: heat demand; forecast; climate change energy procedia ( ) – - copyright © the authors. published by elsevier ltd. selection and peer-review under responsibility of the scientific committee of the applied energy symposium and forum, renewable energy integration with mini/microgrids, rem . /j.egypro. . . . /j.egypro. . . - copyright © the authors. published by elsevier ltd. selection and peer-review under responsibility of the scientific committee of the applied energy symposium and forum, renewable energy integration with mini/microgrids, rem available online at www.sciencedirect.com energy procedia ( ) – www.elsevier.com/locate/procedia - copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the applied energy symposium and forum, renewable energy integration with mini/microgrids, rem . applied energy symposium and forum, renewable energy integration with mini/microgrids, rem , – october , tianjin, china energy demand side management with supply constraints: game theoretic approach sana noora,b, miao guoa, koen h. van dama, nilay shaha, xiaonan wanga,c* acentre for process systems engineering, dept. of chemical engineering, imperial college london, south kensington, london, sw az, uk. benergy futures lab, imperial college london, south kensington, london, sw az, uk. cdepartment of chemical and biomolecular engineering, national university of singapore, singapore abstract the management of energy supply and demand is becoming more challenging in regions where the demand continues to grow rapidly and more intermittent renewable supply sources are added to the energy infrastructure. in this context, demand side management (dsm) can be employed to improve reliability of supply and stretch the capacity limits of the existing grid infrastructure. a game theoretic approach for dsm model incorporating storage components is suggested in this paper for environments with supply constraints. the proposed model is able to not only reduce the peak-to-average ratio to benefit the electric grid, but also smoothen the dips in load profile caused by supply constraints. copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the applied energy symposium and forum, renewable energy integration with mini/microgrids, rem . keywords: demand side management; game theory; storage; supply constraints. . introduction currently, the developing world is facing a major energy crisis. over the recent years, there has been a rapid increase in the demand for electricity, and a similar trend is expected to continue in future with a % increase in demand in next years [ ]. however, access to adequate, reliable and affordable energy remains a major problem. in many cases the growth in demand is much faster than the increase in energy supply due to the time required to build new * corresponding author. tel.: + ; fax: + . e-mail address: chewxia@nus.edu.sg available online at www.sciencedirect.com energy procedia ( ) – www.elsevier.com/locate/procedia - copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the applied energy symposium and forum, renewable energy integration with mini/microgrids, rem . applied energy symposium and forum, renewable energy integration with mini/microgrids, rem , – october , tianjin, china energy demand side management with supply constraints: game theoretic approach sana noora,b, miao guoa, koen h. van dama, nilay shaha, xiaonan wanga,c* acentre for process systems engineering, dept. of chemical engineering, imperial college london, south kensington, london, sw az, uk. benergy futures lab, imperial college london, south kensington, london, sw az, uk. cdepartment of chemical and biomolecular engineering, national university of singapore, singapore abstract the management of energy supply and demand is becoming more challenging in regions where the demand continues to grow rapidly and more intermittent renewable supply sources are added to the energy infrastructure. in this context, demand side management (dsm) can be employed to improve reliability of supply and stretch the capacity limits of the existing grid infrastructure. a game theoretic approach for dsm model incorporating storage components is suggested in this paper for environments with supply constraints. the proposed model is able to not only reduce the peak-to-average ratio to benefit the electric grid, but also smoothen the dips in load profile caused by supply constraints. copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the applied energy symposium and forum, renewable energy integration with mini/microgrids, rem . keywords: demand side management; game theory; storage; supply constraints. . introduction currently, the developing world is facing a major energy crisis. over the recent years, there has been a rapid increase in the demand for electricity, and a similar trend is expected to continue in future with a % increase in demand in next years [ ]. however, access to adequate, reliable and affordable energy remains a major problem. in many cases the growth in demand is much faster than the increase in energy supply due to the time required to build new * corresponding author. tel.: + ; fax: + . e-mail address: chewxia@nus.edu.sg http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf sana noor et al. / energy procedia ( ) – available online at www.sciencedirect.com energy procedia ( ) – www.elsevier.com/locate/procedia - copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the applied energy symposium and forum, renewable energy integration with mini/microgrids, rem . applied energy symposium and forum, renewable energy integration with mini/microgrids, rem , – october , tianjin, china energy demand side management with supply constraints: game theoretic approach sana noora,b, miao guoa, koen h. van dama, nilay shaha, xiaonan wanga,c* acentre for process systems engineering, dept. of chemical engineering, imperial college london, south kensington, london, sw az, uk. benergy futures lab, imperial college london, south kensington, london, sw az, uk. cdepartment of chemical and biomolecular engineering, national university of singapore, singapore abstract the management of energy supply and demand is becoming more challenging in regions where the demand continues to grow rapidly and more intermittent renewable supply sources are added to the energy infrastructure. in this context, demand side management (dsm) can be employed to improve reliability of supply and stretch the capacity limits of the existing grid infrastructure. a game theoretic approach for dsm model incorporating storage components is suggested in this paper for environments with supply constraints. the proposed model is able to not only reduce the peak-to-average ratio to benefit the electric grid, but also smoothen the dips in load profile caused by supply constraints. copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the applied energy symposium and forum, renewable energy integration with mini/microgrids, rem . keywords: demand side management; game theory; storage; supply constraints. . introduction currently, the developing world is facing a major energy crisis. over the recent years, there has been a rapid increase in the demand for electricity, and a similar trend is expected to continue in future with a % increase in demand in next years [ ]. however, access to adequate, reliable and affordable energy remains a major problem. in many cases the growth in demand is much faster than the increase in energy supply due to the time required to build new * corresponding author. tel.: + ; fax: + . e-mail address: chewxia@nus.edu.sg available online at www.sciencedirect.com energy procedia ( ) – www.elsevier.com/locate/procedia - copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the applied energy symposium and forum, renewable energy integration with mini/microgrids, rem . applied energy symposium and forum, renewable energy integration with mini/microgrids, rem , – october , tianjin, china energy demand side management with supply constraints: game theoretic approach sana noora,b, miao guoa, koen h. van dama, nilay shaha, xiaonan wanga,c* acentre for process systems engineering, dept. of chemical engineering, imperial college london, south kensington, london, sw az, uk. benergy futures lab, imperial college london, south kensington, london, sw az, uk. cdepartment of chemical and biomolecular engineering, national university of singapore, singapore abstract the management of energy supply and demand is becoming more challenging in regions where the demand continues to grow rapidly and more intermittent renewable supply sources are added to the energy infrastructure. in this context, demand side management (dsm) can be employed to improve reliability of supply and stretch the capacity limits of the existing grid infrastructure. a game theoretic approach for dsm model incorporating storage components is suggested in this paper for environments with supply constraints. the proposed model is able to not only reduce the peak-to-average ratio to benefit the electric grid, but also smoothen the dips in load profile caused by supply constraints. copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the applied energy symposium and forum, renewable energy integration with mini/microgrids, rem . keywords: demand side management; game theory; storage; supply constraints. . introduction currently, the developing world is facing a major energy crisis. over the recent years, there has been a rapid increase in the demand for electricity, and a similar trend is expected to continue in future with a % increase in demand in next years [ ]. however, access to adequate, reliable and affordable energy remains a major problem. in many cases the growth in demand is much faster than the increase in energy supply due to the time required to build new * corresponding author. tel.: + ; fax: + . e-mail address: chewxia@nus.edu.sg s. noor et al./ energy procedia ( ) – generation capacity, lack of funding and socio-political reasons [ ]. consequently, many developing countries in asia and africa are facing severe supply shortfalls that have resulted in massive rolling black outs, which has caused huge economic loses and devastating influences on citizens’ lifestyles. along with funding constraints the lack of secure and stable energy infrastructure is a result of poor planning, management and maintenance of resources [ ]. distributed renewable energy sources serve as a promising solution to deal with the energy access and scarcity issues. however, when formed as a micro-grid to power demand through renewable resources, it faces many operational challenges to guarantee the reliable and efficient supply, especially in standalone mode not connected to the electrical grid [ ]. demand side management (dsm) techniques are highly relevant and beneficial in the given context. by using dsm demand can be manipulated to match the supply and hence the existing infrastructure can be utilised more efficiently [ ]. the energy system is of heterogeneous nature consisting of multiple consumers each having their own energy usage which makes the system diverse and adds greater flexibility to the system in terms of load scheduling. game theory modelling is ideally applied to describe this problem as it considers the different energy scheduling strategies and payoffs of each player and provides a more holistic approach to analyse the problem [ ]. furthermore, solving the problem in a centralised fashion becomes increasingly challenging due to the wide scope of the problem involving numerous customers and a diverse range of electrical devices. game theory turns the nature of the problem from centralised to distributed, thereby making it computationally easy [ ]. moreover, icts and smart metering technologies have enabled the automation of dsm programs making the process user friendly, and easier to manage. at the same time, it enables data collection that can be used for effective planning and development of the energy sector [ ]. active work is being done in this area. [ ], [ ], and [ ] have introduced frameworks mainly aimed to reduce the peak to average ratio (par) along with the costs for consumers using different pricing incentives. [ ] and [ ] incorporate storage devices into their dsm models. whereas, [ ] and [ ] introduced renewable generation into their analysis of the energy demand management. nevertheless, these models normally assume sufficient energy supply is available from the grid to meet all the demand regardless of costs. this is not applicable in the developing countries where supply is constrained and energy sector is marked by supply shortfalls and load shedding, or in a micro -grid environment where the supply from distributed renewable resources can be frequently interrupted due to the inherent intermittency and uncertainty. the modelling research on the resource-constrained and infrastructure-limiting supply under the developing country context remains a gap; this could be tackled by an extended dsm framework and optimised strategy which help consumers reduce their electricity bills, and provide them with greater flexibility in terms of scheduling load under supply constraints. this study presents a new game theoretic dsm framework to model the supply constrained environments and complexity of individual consumer’s utility and the integrated system performance through demand side management strategies. the model aims to reduce par while trying to lessen the impact of supply constraints and providing cost savings for customers. by reducing the peaks in the system, it will reduce the overall stress on the system and therefore reduce the requirement for building extra generation capacity. the storage units incorporated in the model provide additional energy to drive demand management under load shedding/supply constraints as per consumers’ preferences. thus, it gives consumers more freedom to schedule their loads and lowers their discomfort. the connection of the storage elements to small scale renewables generation such as rooftop solar pv can pave way for a more distributed and efficient energy system. a case study is included in this paper to demonstrate the model functionality, followed by conclusions and future work. . methodology this section discusses a game theory based model suggested for dsm under different supply constraints. it provides detailed mathematical formulation of the model and states the assumptions taken. . . system model the model consists of 𝑛𝑛 consumers, who are connected to the grid, owning two types of load: ) electrical appliances - 𝑎𝑎 and ) storage components - 𝑏𝑏. the model accounts hourly loads for a day, thus the time vector is sana noor et al. / energy procedia ( ) – s. noor et al./ energy procedia ( ) – defined from - hours. furthermore, for each consumer an hourly energy scheduling vector is defined as 𝒍𝒍𝒏𝒏𝒕𝒕 in eq. ( ), which is the sum of energy consumption profile of appliances 𝒙𝒙𝒏𝒏,𝒂𝒂𝒕𝒕 and hourly energy discharge/charge profile for storage component 𝒔𝒔𝒏𝒏,𝒃𝒃𝒕𝒕 . 𝑙𝑙𝑛𝑛𝑡𝑡 = ∑ 𝑥𝑥𝑛𝑛,𝑎𝑎𝑡𝑡 𝐴𝐴𝑛𝑛 𝑎𝑎= + ∑ 𝑠𝑠𝑛𝑛,𝑏𝑏𝑡𝑡 𝐵𝐵𝑛𝑛 𝑏𝑏= ( ) the scheduling vectors have energy constraints given by the power limits and daily energy consumption defined by consumers’ usage of different devices. each appliance will have a time interval for scheduling starting at 𝛼𝛼𝑛𝑛,𝑎𝑎and ending at 𝛽𝛽𝑛𝑛,𝑎𝑎as user-defined parameters. the difference between the two parameters must be equal to or greater than the normal operating hours 𝑂𝑂 to guarantee all tasks fully done. for the non-shiftable appliances, the interval is equal to 𝑂𝑂. outside this interval the devices are off and within this interval the devices can operate at standby power 𝑃𝑃𝑚𝑚𝑚𝑚𝑛𝑛 or maximum power limit 𝑃𝑃𝑚𝑚𝑎𝑎𝑚𝑚 . the daily energy sum of each appliance must be equal to its daily energy consumption level 𝑬𝑬𝑛𝑛,𝑎𝑎 defined by the user. similarly, the storage components are bounded by their maximum energy capacity 𝑬𝑬𝒎𝒎𝒂𝒂𝒙𝒙 𝑛𝑛,𝑏𝑏 , so 𝒔𝒔𝒏𝒏,𝒃𝒃𝒕𝒕 can take any value between - 𝑬𝑬𝒎𝒎𝒂𝒂𝒙𝒙 𝑛𝑛,𝑏𝑏 and + 𝑬𝑬𝒎𝒎𝒂𝒂𝒙𝒙 𝑛𝑛,𝑏𝑏 (negative sign indicates that the storage component is in discharging state). furthermore, the storage components should follow these given bounds, where q represents the initial state-of-charge of battery eq. ( ). ≤ 𝑞𝑞𝑛𝑛,𝑏𝑏 + ∑ 𝑠𝑠𝑛𝑛,𝑏𝑏𝑡𝑡𝑡𝑡 ≤ 𝐸𝐸𝑚𝑚𝑎𝑎𝑚𝑚 𝑛𝑛, 𝑏𝑏 ( ) the sum ∑ 𝒔𝒔𝒏𝒏,𝒃𝒃𝒕𝒕𝐻𝐻𝑡𝑡= = implies that at the end of the day the storage component has the same state as the start of the day. although not necessary in the -hour analysis, this assumption is useful when the spatial and temporal scales of the studied system increase to protect the storage systems. also, at any given point the battery cannot discharge more energy than needed by the devices, as denoted by eq. ( ): ∑ 𝒙𝒙𝑛𝑛,𝑎𝑎𝑡𝑡 𝐴𝐴𝑛𝑛 𝑎𝑎= + ∑ 𝒔𝒔𝑛𝑛,𝑏𝑏𝑡𝑡 𝐵𝐵𝑛𝑛 𝑏𝑏= ≥ ( ) the aggregated load profiles of all consumers can be used to determine the peak-to-average load ratio eq. ( ) on the grid. this represents imbalance in load demand profile. reducing this ratio can help lower the stress on the grid. 𝑃𝑃𝑃𝑃𝑃𝑃 = 𝐿𝐿_𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝/𝐿𝐿_𝑝𝑝𝑎𝑎𝑎𝑎 ( ) . . cost model the costs on consumers can be defined by a sum of the price of electricity 𝑷𝑷𝒕𝒕 (𝐿𝐿𝑡𝑡 ) (eq.( )) and cost of discomfort 𝑫𝑫𝒏𝒏,𝒕𝒕(𝑙𝑙𝑛𝑛𝑡𝑡 ) (eq.( )) that the users face when they shift their loads. the adopted price is an increasing function of the aggregated load in the system, while the discomfort cost depends on the difference between the initial schedule ȴ_𝒔𝒔𝒔𝒔𝒔𝒔𝒏𝒏𝒕𝒕 specified by the consumer and the optimized schedule followed after load shifting. 𝒘𝒘𝒏𝒏,𝒂𝒂 represents the willingness of consumers to shift the load of various appliances, a lower value means higher willingness to shift load. 𝑃𝑃𝑡𝑡 (𝐿𝐿𝑡𝑡 ) = 𝑎𝑎 ∗ 𝐿𝐿𝑡𝑡 ( ) 𝐷𝐷𝑛𝑛,𝑡𝑡,𝑎𝑎 (𝑙𝑙𝑛𝑛𝑡𝑡 ) = ((𝑙𝑙𝑛𝑛𝑡𝑡 − ȴ_𝑠𝑠𝑠𝑠ℎ𝑛𝑛𝑡𝑡 )^ ) ∗ 𝑤𝑤𝑛𝑛,𝑎𝑎 ( ) . . load constraints in an environment with supply constraints due to load shedding, the above energy consumption profiles will bear additional constraints. let 𝒁𝒁𝒕𝒕 ≙ {𝑧𝑧 𝑡𝑡 , . . . , 𝑧𝑧ℎ𝑡𝑡 } define the loading shedding schedule, in which the time slots denote the hours of scheduled power cuts by the utility. during this period, the battery can only operate in two states; discharge or stay idle as depicted by eq. ( ): sana noor et al. / energy procedia ( ) – s. noor et al./ energy procedia ( ) – defined from - hours. furthermore, for each consumer an hourly energy scheduling vector is defined as 𝒍𝒍𝒏𝒏𝒕𝒕 in eq. ( ), which is the sum of energy consumption profile of appliances 𝒙𝒙𝒏𝒏,𝒂𝒂𝒕𝒕 and hourly energy discharge/charge profile for storage component 𝒔𝒔𝒏𝒏,𝒃𝒃𝒕𝒕 . 𝑙𝑙𝑛𝑛𝑡𝑡 = ∑ 𝑥𝑥𝑛𝑛,𝑎𝑎𝑡𝑡 𝐴𝐴𝑛𝑛 𝑎𝑎= + ∑ 𝑠𝑠𝑛𝑛,𝑏𝑏𝑡𝑡 𝐵𝐵𝑛𝑛 𝑏𝑏= ( ) the scheduling vectors have energy constraints given by the power limits and daily energy consumption defined by consumers’ usage of different devices. each appliance will have a time interval for scheduling starting at 𝛼𝛼𝑛𝑛,𝑎𝑎and ending at 𝛽𝛽𝑛𝑛,𝑎𝑎as user-defined parameters. the difference between the two parameters must be equal to or greater than the normal operating hours 𝑂𝑂 to guarantee all tasks fully done. for the non-shiftable appliances, the interval is equal to 𝑂𝑂. outside this interval the devices are off and within this interval the devices can operate at standby power 𝑃𝑃𝑚𝑚𝑚𝑚𝑛𝑛 or maximum power limit 𝑃𝑃𝑚𝑚𝑎𝑎𝑚𝑚 . the daily energy sum of each appliance must be equal to its daily energy consumption level 𝑬𝑬𝑛𝑛,𝑎𝑎 defined by the user. similarly, the storage components are bounded by their maximum energy capacity 𝑬𝑬𝒎𝒎𝒂𝒂𝒙𝒙 𝑛𝑛,𝑏𝑏 , so 𝒔𝒔𝒏𝒏,𝒃𝒃𝒕𝒕 can take any value between - 𝑬𝑬𝒎𝒎𝒂𝒂𝒙𝒙 𝑛𝑛,𝑏𝑏 and + 𝑬𝑬𝒎𝒎𝒂𝒂𝒙𝒙 𝑛𝑛,𝑏𝑏 (negative sign indicates that the storage component is in discharging state). furthermore, the storage components should follow these given bounds, where q represents the initial state-of-charge of battery eq. ( ). ≤ 𝑞𝑞𝑛𝑛,𝑏𝑏 + ∑ 𝑠𝑠𝑛𝑛,𝑏𝑏𝑡𝑡𝑡𝑡 ≤ 𝐸𝐸𝑚𝑚𝑎𝑎𝑚𝑚 𝑛𝑛, 𝑏𝑏 ( ) the sum ∑ 𝒔𝒔𝒏𝒏,𝒃𝒃𝒕𝒕𝐻𝐻𝑡𝑡= = implies that at the end of the day the storage component has the same state as the start of the day. although not necessary in the -hour analysis, this assumption is useful when the spatial and temporal scales of the studied system increase to protect the storage systems. also, at any given point the battery cannot discharge more energy than needed by the devices, as denoted by eq. ( ): ∑ 𝒙𝒙𝑛𝑛,𝑎𝑎𝑡𝑡 𝐴𝐴𝑛𝑛 𝑎𝑎= + ∑ 𝒔𝒔𝑛𝑛,𝑏𝑏𝑡𝑡 𝐵𝐵𝑛𝑛 𝑏𝑏= ≥ ( ) the aggregated load profiles of all consumers can be used to determine the peak-to-average load ratio eq. ( ) on the grid. this represents imbalance in load demand profile. reducing this ratio can help lower the stress on the grid. 𝑃𝑃𝑃𝑃𝑃𝑃 = 𝐿𝐿_𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝/𝐿𝐿_𝑝𝑝𝑎𝑎𝑎𝑎 ( ) . . cost model the costs on consumers can be defined by a sum of the price of electricity 𝑷𝑷𝒕𝒕 (𝐿𝐿𝑡𝑡 ) (eq.( )) and cost of discomfort 𝑫𝑫𝒏𝒏,𝒕𝒕(𝑙𝑙𝑛𝑛𝑡𝑡 ) (eq.( )) that the users face when they shift their loads. the adopted price is an increasing function of the aggregated load in the system, while the discomfort cost depends on the difference between the initial schedule ȴ_𝒔𝒔𝒔𝒔𝒔𝒔𝒏𝒏𝒕𝒕 specified by the consumer and the optimized schedule followed after load shifting. 𝒘𝒘𝒏𝒏,𝒂𝒂 represents the willingness of consumers to shift the load of various appliances, a lower value means higher willingness to shift load. 𝑃𝑃𝑡𝑡 (𝐿𝐿𝑡𝑡 ) = 𝑎𝑎 ∗ 𝐿𝐿𝑡𝑡 ( ) 𝐷𝐷𝑛𝑛,𝑡𝑡,𝑎𝑎 (𝑙𝑙𝑛𝑛𝑡𝑡 ) = ((𝑙𝑙𝑛𝑛𝑡𝑡 − ȴ_𝑠𝑠𝑠𝑠ℎ𝑛𝑛𝑡𝑡 )^ ) ∗ 𝑤𝑤𝑛𝑛,𝑎𝑎 ( ) . . load constraints in an environment with supply constraints due to load shedding, the above energy consumption profiles will bear additional constraints. let 𝒁𝒁𝒕𝒕 ≙ {𝑧𝑧 𝑡𝑡 , . . . , 𝑧𝑧ℎ𝑡𝑡 } define the loading shedding schedule, in which the time slots denote the hours of scheduled power cuts by the utility. during this period, the battery can only operate in two states; discharge or stay idle as depicted by eq. ( ): s. noor et al./ energy procedia ( ) – 𝑠𝑠𝑛𝑛,𝑏𝑏𝑡𝑡 ≤ , 𝑡𝑡 ⋲ 𝑍𝑍𝑡𝑡 ( ) meanwhile, the appliances can just get their energy supply from the storage components as denoted in eq. ( ). ∑ 𝑥𝑥𝑛𝑛,𝑎𝑎𝑡𝑡 𝐴𝐴𝑛𝑛 𝑎𝑎= ≤ ∑ 𝑠𝑠𝑛𝑛,𝑏𝑏𝑡𝑡 𝐵𝐵𝑛𝑛 𝑏𝑏= , 𝑡𝑡 ⋲ 𝑍𝑍𝑡𝑡 ( ) furthermore, the cost functions will change in a supply-constrained environment. the electricity price, 𝑃𝑃𝑡𝑡 (𝐿𝐿𝑡𝑡 ) will take the form of a piece-wise function given in eq. ( ), defined by an increasing quadratic function during electricity provision hours and equal to during the power cut hours. 𝑃𝑃𝑡𝑡 (𝐿𝐿𝑡𝑡 ) = 𝑔𝑔 ∗ 𝐿𝐿𝑡𝑡 𝑡𝑡 ⋶ 𝑍𝑍𝑡𝑡 ; 𝑃𝑃𝑡𝑡 (𝐿𝐿𝑡𝑡 ) = 𝑡𝑡 ⋲ 𝑍𝑍𝑡𝑡 ( ) . . game theory model a game theory model is proposed in this work, which is defined by all involved players, their strategies and the corresponding payoffs. in this model, the consumers act as players and thus 𝑛𝑛 defines the set of players going from , …, n. the strategies are the energy scheduling vectors 𝑥𝑥𝑛𝑛,𝑎𝑎𝑡𝑡 and𝑠𝑠𝑛𝑛,𝑏𝑏𝑡𝑡 that the players desire to optimize in order to increase their payoffs, i.e. reduce their costs. as each player is concerned about their own payoffs, the aggregated load can be broken into load of the nth consumer and load of all other consumers in the system. thus the payoffs for consumer n can be defined as eq. ( ) 𝐶𝐶(𝑙𝑙𝑛𝑛𝑡𝑡 ) = ∑ ((𝑔𝑔 ∗ (𝑙𝑙𝑛𝑛𝑡𝑡 + 𝑙𝑙𝑚𝑚𝑡𝑡 )) + ∑ 𝑤𝑤𝑛𝑛,𝑎𝑎 ∗ (𝑙𝑙𝑛𝑛 𝑡𝑡 − ȴ𝑠𝑠𝑠𝑠ℎ 𝑛𝑛,𝑎𝑎 𝑡𝑡 ) 𝐴𝐴𝑛𝑛𝑎𝑎= )𝑇𝑇𝑡𝑡= 𝑛𝑛 𝑡𝑡 ( ) . . implementation at the start of the day, the utility company will gather the schedules from all consumers and based on that it will forward the aggregated load for each hour to consumers. having this information beforehand, the gaming algorithm will be run at each consumer’s end to optimize their energy scheduling profiles. if they make changes to the schedule, they will submit any variations to the utility. thus, utility will keep forwarding the updated aggregated load to all consumers until no further changes are made and an optimum solution is reached for all. . case study and results discussion in this illustrative case study, a data set for consumers was used, each having appliances, among which are shiftable (e.g., dishwasher, washing machine, refrigerator and boiler) and non-shiftable (e.g., lights, and tv). furthermore, each user owns a battery with a capacity of kwh for energy storage. the model was built and solved in gams . . using ipopt solver. figure . and figure . represent the load profiles from the grid and consumers’ perspectives, respectively. figure . first illustrates the reduction of par for dsm model with respect to the original load profile. when storage is included there is a par reduction of %, compared to % reduction without storage. figure . further highlights the importance of energy storage for consumers. storage load can be scheduled during power cut hours and hence dips in the profile are reduced. sana noor et al. / energy procedia ( ) – s. noor et al./ energy procedia ( ) – figure . load profiles as seen by grid figure . consumers load profile depending on priority of appliances, captured by the willingness parameter and the storage capacity, load is scheduled as per consumer preferences. in figure , it can be seen that the dips are shallower for dsm model with storage. the model gives consumers power to schedule their loads under outage hours using their storage devices and hence their discomfort costs are significantly reduced as they are able to schedule the entire load in outage hours as per demand. this is shown in figure , where the lower bound of demand profile is closely tracked by the model with storage. figure highlights the reduction in bills for the consumers for the same scenario shown above, note this does not show the total payoffs, as payoff is both the bills and discomfort costs combined. figure provides a summary of all the payoffs for three different scenarios namely, , , and -hoursof power cuts respectively. it is demonstrated the peak-to-average ratio and overall bill reductions decrease with increasing power outages, as the overall flexibility to manipulate load reduces. in addition, the third benefit to smoothen the dips is met. figure , shows the extra load scheduled in each scenario. figure . cost comparison figure . payoff gains . conclusion we have presented a game theoretic model for dsm that incorporates storage components and takes into account the supply constraints in the form of power outages. in context of developing world, smart energy control and demand side management can be vital to bridge the continuously increasing supply and demand gaps. not only is dsm a meaningful approach for maintaining the supply and demand balance and reduce stress on grid, it also delivers benefits to customers by reducing their utility bill. the game theoretic approach captures the needs of every individual and helps to exploit the diversity of load profiles of the consumers set. furthermore, the storage elements are used to supply power at load shedding hours. this delivers additional benefits to the consumers by lessening the impact of power cuts through scheduling load via storage devices. the results of the model demonstrate the par reduction along with the decrease in the load dips for consumers, hence making the overall load profile smoother. dsm is proved to be a useful tool to cater for the growing demand meanwhile the new generation capacity is built. sana noor et al. / energy procedia ( ) – s. noor et al./ energy procedia ( ) – figure . load profiles as seen by grid figure . consumers load profile depending on priority of appliances, captured by the willingness parameter and the storage capacity, load is scheduled as per consumer preferences. in figure , it can be seen that the dips are shallower for dsm model with storage. the model gives consumers power to schedule their loads under outage hours using their storage devices and hence their discomfort costs are significantly reduced as they are able to schedule the entire load in outage hours as per demand. this is shown in figure , where the lower bound of demand profile is closely tracked by the model with storage. figure highlights the reduction in bills for the consumers for the same scenario shown above, note this does not show the total payoffs, as payoff is both the bills and discomfort costs combined. figure provides a summary of all the payoffs for three different scenarios namely, , , and -hoursof power cuts respectively. it is demonstrated the peak-to-average ratio and overall bill reductions decrease with increasing power outages, as the overall flexibility to manipulate load reduces. in addition, the third benefit to smoothen the dips is met. figure , shows the extra load scheduled in each scenario. figure . cost comparison figure . payoff gains . conclusion we have presented a game theoretic model for dsm that incorporates storage components and takes into account the supply constraints in the form of power outages. in context of developing world, smart energy control and demand side management can be vital to bridge the continuously increasing supply and demand gaps. not only is dsm a meaningful approach for maintaining the supply and demand balance and reduce stress on grid, it also delivers benefits to customers by reducing their utility bill. the game theoretic approach captures the needs of every individual and helps to exploit the diversity of load profiles of the consumers set. furthermore, the storage elements are used to supply power at load shedding hours. this delivers additional benefits to the consumers by lessening the impact of power cuts through scheduling load via storage devices. the results of the model demonstrate the par reduction along with the decrease in the load dips for consumers, hence making the overall load profile smoother. dsm is proved to be a useful tool to cater for the growing demand meanwhile the new generation capacity is built. s. noor et al./ energy procedia ( ) – the storage components were also modelled in a grid connected mode, and they can be combined with renewable generation sources to help reduce the stress on grid further. in future work, we will adapt the methodology to be combined with our previously studied hybrid renewable energy powered micro-grid to show its wider applicability. we will also scale up the current analysis to a real-world context and obtain a comprehensive costs and benefits analysis for the whole society. acknowledgements s. noor acknowledges the financial support by the commonwealth scholarship commission in the uk. x. wang thanks the moe acrf tier grant in singapore for financial support to the project “pathways to resilient food- energy-water-waste nexus” (r- - - - ). references [ ] international energy outlook -world energy demand and economc outlook. energy information administration; [ ] d. mulongoti, g. mugala, b. kumwenda, h. louie. determining the effects of load-shedding on residential electricity consumption using meter data — a case study of kitwe, zambia. global humanitarian technology conference (ghtc) . [ ] lauren m. maclean, george m. bob-milliar, elizabeth baldwin, elisa dickey. the construction of citizenship and the public provision of electricity during the world cup in ghana. the journal of modern african studies ; : – . [ ] xiaonan wang, ahmet palazoglu, nael h.el-farra. operational optimization and demand response of hybrid renewable energy systems. applied energy ; : - . [ ] amir-hamed mohsenian-rad, vincent w. s. wong, juri jatskevich, robert schober, alberto leon-garcia. autonomous demand-side management based on game-theoretic energy consumption scheduling for the future smart grid. ieee transactions on smart grid ; - . [ ] roger a mccain. game theory: a nontechnical introduction to the analysis of strategy. rd ed. world scientific; . [ ] zubair md. fadlullah,duong minh quan, nei kato, ivan stojmenovic. gtes: an optimized game-theoretic demand-side management scheme for smart grid. ieee systems journal . [ ] ijeoma onyeji-nwogu, morgan bazilian, todd moss.the digital transformation and disruptive technologies: challenges and solutions for the electricity sector in african markets. cgd policy paper ; - . [ ] linqi song, yuanzhangxiao, mihaela van der schaar. demand side management in smart grids using a repeated game framework. ieee journal on selected ares in communications ; - . [ ] hung khanh nguyen, ju bin song, zhu han. distributed demand side management with energy storage in smart grid. ieee transactions on parallel and distributed systems . [ ] hazem msoliman, alberto leon-garcia. game-theoretic demand-side management with storage devices for the future smart grid. ieee transactions on smart grid ; . : - . [ ] chenye wu, hamed mohsenian-rad, jianwei hunag, amy yuexuan wang. demand side management for wind power integration in microgrid using dynamic potential game theory. ieee international workshop on smart grid communications and networks . [ ] xiaonan wang, nael h.el-farra, ahmet palazoglu. optimal scheduling of demand responsive industrial production with hybrid renewable energy systems. renewable energy ; : - . proc. nat. acad. sci. usa vol. , no. , pp. - , augutst initiatives for the future of energy edward e. david, jr. science adviser to the president of the united states contributed to symposium on energy for the future, april , the energy situation is a microcosm of the problems facing the nation. it contains all the elements that deny a straight- forward technical solution. both public and private interests are involved. there is a cost-benefit trade-off between energy supply and environmental quality. burgeoning demand for energy threatens to deplete basic natural re- sources, yet conservation has not been a deliberate policy. tax incentives and import quotas greatly affect the eco- nomics of new technology. the energy industry is highly regulated by state and federal commissions. their rate structures affect virtually every person and enterprise in the nation. the uses of energy permeate all of our high-technology culture. any change in supply or demand has profound impacts on the quality of life. national security is involved in fixing the sources of the nation's energy supply. public argument, not always enlightened, clouds the picture of safety and acceptability of power plants. there is no doubt that energy usage on an increasing scale is vital to economic health. it seems clear enough that a national goal of high priority is an abundant supply of in- expensive, clean energy. we are not hopelessly far from that goal today, but how are we to achieve it despite the com- plexities and uncertainties of the next few decades? what role can science and technology play? as is usual, the answers begin to come with the realization that the options available to us for action today are not acceptable for the future. new options are needed and these must come from science and technology. choosing among the available options at any time also requires science and technology, particularly the social sciences verging into the value system of our society. for example, we need the option to burn the vast supplies of high-sulfur coal available without the high level of sulfur oxide pollution that goes with it today. we need the option to make the most of our natural uranium supplies and to dispose safely of the lethal wastes that are generated. we need the option of using unconventional power sources such as solar energy. we need the option of developing new natural resources such as oil shale and gas supplies in low permeability rock. we need the option of more efficient conversion from fuel to electricity to keep down thermal pollution. we need the option of burying high-voltage power transmission cable. last, but far from least, we need what tv commercials might call "the-unheard-of" option; the one we haven't yet con- ceived. that must come from basic research. from where we are today there are many avenues to be explored. let me in the remainder of this talk try to set the scene and point to a few directions as potentially providing vitally-needed op- tions. some have said that there is an "energy crisis". others have denied it. i wouldn't care to argue the point, for crises are highly personal perceptions. however, during the past year there have been black-outs, brown-outs or voltage reductions, and potential fuel shortages that have given the public valid concern for their energy supply. the sources of these happenings are many-unreliability of equipment is one, political disturbances in the middle east another, and a shortage of investment by industry a third. (by the way, the energy industry is one of the most capital-intensive in the economy. it accounts for about % of all capital investment in new plant and equipment.) however, the strongest factors in today's energy picture are the opposing influences of growth and the environment. energy consumption has grown rapidly during the past years, much more rapidly than earlier, while our concerns for environmental protection have created new, severe demands. after growing at around % per year from the second world war until , total energy growth averaged nearly % per year during the last half of the s. last year, overall energy consumption grew at about %. in the last few years, electric consumption has grown at an average annual rate of % and in and hit %. thus, projecting future energy needs , , or even years is a difficult task. extrapolation from the past is in serious question. recent energy price increases after years of decrease or stability suggest to some economists that there will be a slowing of growth. roughly, over the next years, the cumulative demand is likely to amount to - x btu. perhaps the most difficult question is the effect of environmental and resource limits on energy supply. when one projects the pollution and other environmental problems resulting from today's energy production and consumption technology to or , the prospects become frightening. the vast amounts of sulfur oxides, particulates, waste heat, and radioactivity that are generated, as well as the land and fuels consumed, lead one to wonder how long such growth can continue without irreversible damage. it is this potential divergence in energy demand and supply that has created the so-called "energy crisis" and which calls for new options for the future. there is no dearth of oppor- tunity for creating them. first, consider fossil fuels. coal, oil, and natural gas supply all but % of our current energy needs and will continue to be the dominant source for the remainder of this century at least. at present, the major problems associated with fossil fuels involve air pollution, but the long-term supply picture for oil and gas is worrisome. current and projected reserves are not adequate to meet future demand by anyone's estimate. furthermore, oil and gas must supply not only the energy d o w n lo a d e d a t c a rn e g ie m e llo n u n iv e rs ity o n a p ri l , proc. nat. acad. sci. usa ( ) industry but the chemical industry as well, supplying process inputs, lubricants, and transportation fuel. coal is the most abundant fossil fuel in the united states. there are vast reserves, but coal unfortunately presents the most severe sulfur and particulate problem. a broad range of r&d areas must be pursued to enable coal to provide its share of our energy needs in the decades to come. the most urgent area involves controlling the sulfur oxides and other air pollutants from stationary com- bustion sources. currently, there are no commercially avail- able means of burning high-sulfur coal and oil in accordance with air pollution regulations, as you can read in the april , issue of the new york times business section. stack gas-cleaning systems that remove the pollutants from the gas stream are the closest at hand. there are a wide variety of such processes and several of them are now in the large-scale demonstration phase. these processes generally start by reac- ting the sulfur oxides in the flue gas with another compound in an aqueous scrubber. when limestone is used, the resulting compound, caso , is thrown away, but the other intermediate products are regenerated, producing a marketable sulfur by- product. the results of some of these demonstrations should be available in or years. a good deal of this work is sup- ported by epa through its national air pollution control office. for fiscal year , the program amounts to some $ x . unfortunately, all of these stack gas-cleaning processes will add to the cost and complexity of the combustion system and may reduce its efficiency. we therefore need to look at more fundamental changes. the work here is not so far advanced, but there are several promising approaches involving fluidized bed combustion, combined gas turbine-steam turbine cycles, and magnetohydrodynamics (mhd). fluidized bed combustion is a different way of burning coal at reduced combustion temperature, facilitating the reaction of sulfur with limestone. the result is expected to be a less expensive boiler, with reduced sulfur and nitrogen oxide emissions. the combined gas turbine-steam turbine cycle is intended for use with low-btu gas made from coal at the plant site. the gas is hot-cleaned and burned directly in the gas turbine. studies indicate that in second- or third-generation designs the low-quality gas can be made from coal in a relatively simple gasification step, the sulfur removed primarily as hydrogen sulfide (rather than so ), and the gas used to generate electricity at overall efficiencies approaching %. one of the key elements in this high efficiency, which com- pares with conventional steam cycle efficiencies of about %, is the use of high-temperature aircraft technology in the gas turbine. potential sulfur-removal efficiencies approaching %, as compared to the % removal expected for stack gas- cleaning processes, are also expected. mhd is another topping cycle. it converts the kinetic energy in a stream of hot combustion gas directly to electric power with no mechanical moving parts. the very high temperatures ( - 'f) involved cause materials prob- lems and may result in significantly more nitrogen oxides than conventional units. preliminary estimates suggest that advanced mhd plants may approach efficiencies of %. work on all of these advanced concepts is still at a low level of funding by government and industry. more effort is needed, but here we encounter the problems of government funding of commercially-targeted r&d. r&d in the energy field is particularly vexing in this regard. it is a long and costly road from a theoretical under- standing and a laboratory demonstration to a commercially feasible technology. there are at least three recognizable stages culminating in a full-scale demonstration of feasibility. the last two stages, pilot and demonstration plants, are quite expensive and time-consuming. i need only to point out that some - years passed from the chicago pile experiment to the commercial nuclear reactors of today. this high cost and deferred pay-off, combined with the fragmentation of the industry, is one of the stickiest points in the energy picture. clearly, the federal government has an important role to play and close cooperation with industry is a necessity. moving beyond electric production to other forms of energy consumption, we find that the cleanest fuels, gas and oil, are in the shortest supply from a resource point of view. natural gas in particular is clean with respect to its pro- duction, transportation, and especially consumption, so it is no wonder that demand has been increasing more rapidly than for other fossil fuels. this trend is expected to continue as new air-pollution standards are implemented. coal gasifi- cation offers the best possibility for augmenting our domestic supplies of clean gaseous fuel. a number of processes have been under development by the interior department and industry to convert coal to high-btu pipeline quality gas. this is a more difficult task than making the low-btu producer gas needed for combined-cycle power plants i mentioned pre- viously and requires an extensive r&d effort. the depart- ment of interior is financing a program of coal gasification at $ million/year.* although coal can also be converted to clean liquid fuels, our vast oil shale reserves in the rocky mountain area offer the best potential for augmenting our supplies of liquid fuels. for many years people have realized the value of this resource, but because of a number of legal, economic, and technical problems, oil shale is not yet a commercial reality. there are two basic approaches to recovering the shale oil. one can either mine the rock and produce the oil in large retorts or one can try to recover the oil in place. the second approach is more difficult technically but would reduce environmental problems. nuclear power offers a means of greatly increasing the nation's supply of clean energy. over the past two decades we have made a great deal of progress with the light-water con- verter reactors. these are now on the verge of providing a significant share of electric generation. safety and many environmental protection systems have been designed into these plants from the start. it therefore troubles me to hear the many objections to individual nuclear power plants being raised when the only alternative is to build additional fossil- fuel plants. in the area of pollution control, nuclear power plants stand far ahead of most fossil-fuel plants. the radioactive discharge systems of all nuclear plants are designed to meet well-established standards, and frequently the actual releases are only a small fraction of these standards. on the fossil-fuel side, the effluent control technology is much less satisfactory. of course, current generation nuclear plants are somewhat less efficient than fossil plants, so their waste- heat discharge problem is greater. there are some interesting possibilities here, too; for example, reactors employing closed- * increased by $ million in the presidents' june energy mes- sage. david: initiatives d o w n lo a d e d a t c a rn e g ie m e llo n u n iv e rs ity o n a p ri l , n. a. s. symposium: energy for the future cycle gas turbines could permit the use of much smaller and more esthetically pleasing cooling towers than is possible with the usual steam cycle. the objections to the disposal of high level radioactive wastes from nuclear power plants also show uneven thinking. the atomic energy commission, with the help of the na- tional academy of sciences, conducted extensive studies and tests on the solidification and disposal techniques which are to be used at the salt-mine repository near lyons, kansas. there are always some unanswered questions which must be researched, but those associated with high-level radio- active waste disposal seem to me to be of less significance than those such as subsidence and acid mine drainage asso- ciated with the mining of coal, for example. for the future we need to move beyond the current reactors to breeders which will increase the effective utilization of uranium from or % to or %. this increase means not only that we can make better use of our existing low cost uranium resources, but also that vast quantities of low-grade uranium not economical today would become available to meet the nation's energy needs in the next century and beyond. the united states and many other nations in the world are moving ahead with breeder reactor development programs. generally the highest priority has been given to the liquid metal fast breeder reactor (lmfbr). in this country we al- ready have several test reactors in operation and are building a large fast-flux test facility. the next logical step is the con- struction of a large demonstration plant in cooperation with industry to integrate all of the many components in this system. this program is funded through the aec; in fiscal year a total of $ milliont is allocated. the breeder reactor is so important to the nation's future energy supplies that we should have a significant back-up effort involving alternative concepts. currently we are pursuing a small effort on the fast-gas reactor, which uses essentially the same fuel as the lmfbr but a different, perhaps easier-to-handle coolant. the molten-salt concept being pursued at oak ridge is fundamentally different and therefore has merit as a completely independent approach. hopefully, the nation will be able to make additional funds available to pursue these back-up concepts on an expanded basis. as i mentioned earlier, however, the final stages of development can be exceedingly expensive. while the breeder reactor is expected to become a commer- cially important energy system in the s, nuclear fusion has great promise for the decades beyond. during the past three or four years significant progress has been made toward the demonstration of the scientific feasibility of controlled fusion. we are still several years away from this elusive goal, but many investigators believe it is finally in sight. after this key step is achieved, we still have the lengthy development process before us. as we found out in the fission reactor business, there are many alternative power systems which look attractive on paper, but materials and other engineering problems are an unmerciful sieve. after a series of small-scale t increased by $ million in the presidents' june energy mes- sage. pilot plants, we would then need to move to larger-scale facilities and eventually full-scale demonstration. based on past practice, i would guess that it will take until about the turn of the century before fusion could become a commercially significant source of power. its benefits, however, appear to be worth the long effort. advanced fusion reactors will use the virtually unlimited deuterium found in sea water as fuel, so that fuel supply should not be a problem. fusion reactors are also expected to generate less radioactive wastes, and if direct conversion is achieved, thermal pollution could also be minimized. the promise of advanced new power systems is not limited to nuclear energy. two others of some promise, particularly in certain geographic areas, are solar energy and geothermal steam. we have yet to learn how to convert these to useful electric power on an economical basis, but during the last several years some intriguing possibilities have been sug- gested. these concepts have a long way to go technically and economically. one cannot say with any assurance that they will prove successful, but i think the nation must investigate these new approaches at least to the point of feasibility. less spectacular perhaps than totally new energy systems, but also deserving of attention, are improvements in energy utilization or consumption technology. we should encourage exploitation of the second law of thermodynamics, including improved insulating materials, heat exchangers for recovering energy in exhausts, microwave ovens, thermoelectric refrigera- tion, thermoluminescent lighting panels and so on. the effi- ciency of energy consumption is a significant and relatively unexplored dimension. there are, of course, many other energy technologies which i could have mentioned and which should all be part of a national energy r&d program. currently, however, there is no such balanced program, although various government agencies and industries are working in a number of the more promising areas. a step toward development of a compre- hensive program is the president's proposed reorganization plan which would create a department of natural resources. one of the tasks of this agency would be to formulate a balanced r&d strategy serving both our near and long- term needs for clean energy. it goes without saying, however, that energy r&d defies programming from a single focus. there are, and will continue to be, too many conflicting interests and authorities. this, however, is the shape of the future in many priority fields. difficulties of this sort often yield to cooperation and compromise between the competing parties. even logic can play a role. but by far the greatest influence for progress must come from the new options- particularly the unheard-of-options that i mentioned earlier. for these we need the academic community with its insistence on, and tradition of, understanding as a basis for action. nsf will be calling on the universities for this uncommon effort in energy through its new program, rann. i have great expectations for the coupling so achieved-i'm reminded of h. l. mencken's saying: "some problems are so difficult that they cannot be solved in a million years unless some one thinks about them for five minutes." in any case, progress on the energy front will depend on an extraordinary alliance between governments, industries, and the universities. proc. nat. acad. sci. usa ( ) d o w n lo a d e d a t c a rn e g ie m e llo n u n iv e rs ity o n a p ri l , nutrition as medicine to improve outcomes in adolescents sustaining a sports-related concussion exploratory research and hypothesis in medicine vol. | – copyright: © authors. this is an open access article distributed under the terms of the creative commons attribution-noncommercial . international license (cc by-nc . ), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. review article introduction sports-related concussion (src), like other acute traumatic brain injuries (tbis), involves mechanical forces that shear neuronal, glial and endothelial membranes, inducing a complex pathophysi- ologic process that adversely affects the brain. , collectively, these forces induce a primary response involving neuronal and tissue damage, which is subsequently amplified by a ‘secondary injury’ phase in response to membrane and cellular damage. this encompasses a cascade of biochemical changes that impairs func- tion of the blood–brain barrier, compromises oxygenation and po- tentiates further tissue damage. targeted patient education and improved protective equipment has led to some decrease in primary injury. however, to date, the adverse health effects of secondary injury (e.g., sleep disruption, depression, impulsivity, decline in cognitive function, migraine, impaired vision) have not been met with effective treatment. it is generally considered that decline in neuropsychological function- ing is transient, resolving to pre-injury benchmarks within – days, with the timeline paralleling the acute neurometabolic events triggered by the concussive impact. however, reports link- ing the injury to long-term declines in cognitive functioning, , de- pression and mild cognitive impairment has propagated substantial scrutiny of the “transient nature” of src, – particularly during adolescence. the injured adolescent brain poses a unique complexity to un- derstanding the pathophysiology of concussion from the incident to the recovery process which extend investigation beyond adult trauma, rodent models and cell culture towards longitudinal stud- ies assessing the short- and long-term intricate cognitive, emotion- al, behavioral, neurobiological and neuropathological consequenc- es of concussions that can also identify predictors and modifiers nutrition as medicine to improve outcomes in adolescents sustaining a sports-related concussion krista casazza * and erin swanson university of alabama at birmingham, department of pediatrics, division of adolescent medicine, birmingham, al , usa; university of alabama at birmingham, department of pediatrics, division of rehabilitative medicine, birmingham, al , usa abstract recognition and diagnosis of sports-related concussion (src) among adolescents has significantly increased. in, fact, among high school adolescents, src incidence has more than doubled from to , with recent es- timates at approximately per athletes. src-related research has also increased; recognition of symptoms that may prolong recovery have been examined, potential biomarkers have been scrutinized, return-to-learn and return-to-play protocols have been developed and honed. however, to date, clinicians and researchers have struggled to find effective interventions to mitigate the significant symptoms after src and shorten recovery times. despite the understood role of the brain as the primary regulator of metabolism, and the well-established metabolic impairments evoked after a concussion, nutrition is often ignored as a core complement to the re- covery and rehabilitation process. in this article, we will identify deficiencies and/or inadequacies in nutrients post-concussion and provide support for potential exacerbation of injury and delayed recovery due to inadequate intake of nutrients prior to sustaining an src. additionally, we will discuss the effect of derangement of the metabolic cascade post-concussion, and identify key nutrients, that if supplemented immediately post-injury, could increase neuroprotection, and improve recovery outcomes. animal and cell culture studies have provided substantial evidence for not only the interrelationship of nutrient adequacy and the adaptation in the metabolic cascade post-concussion on neuroprotection, but also key nutrients that if supplemented immediately post-injury could enhance standard of care with minimal risk. keywords: sports-related concussion; adolescent; athlete; nutrition. abbreviations: src, sports-related concussion; tbi, traumatic brain injury; pufa, polyunsaturated fatty acid; dha, decosahexanoic acid; atp, adenosine triphosphate; bcaas, branched chain amino acids; cns, central nervous system; adp, adenosine diphosphate; crp, c-reactive protein; ala, alpha-linoleic acid; vdr, vitamin d re- ceptor; bbb, blood brain barrier; nadph, nicotinamide adenine dinucleotide phos- phate; tca, tricarboxylic acid; parp- , poly-adenosine diphosphate-ribose polymer- ase- ; gh, growth hormone. received: august , ; revised: september , ; accepted: october , *correspondence to: krista casazza, university of alabama at birmingham, depart- ment of pediatrics, division of rehabilitative medicine, th ave s, cppi , birmingham, al , usa. e-mail: kcasazza@peds.uab.edu how to cite this article: casazza k, swanson e. nutrition as medicine to improve outcomes in adolescents sustaining a sports-related concussion. exploratory re- search and hypothesis in medicine ; ( ): – . doi: . /erhm. . . http://creativecommons.org/licenses/by-nc/ . / doi: . /erhm. . | volume issue , december casazza k. et al: nutrition in sports-related concussion explor res hypothesis med of outcomes. clinical studies have focused predominantly on descriptive or observational investigations into qualitative symp- toms and/or semi-quantitative analysis of cognitive impairments. as such, important elements of the underlying pathophysiology of concussion have been delineated through experimental models and reports of the long-term effects of concussion in adult athletes (e.g., the national football league). data collected in adults and animals, however, are unable to ac- count for developmental differences and changes in mental status, respectively. for example, kerr et al. highlighted a difference in return-to-play times in adolescents demonstrating the unique adap- tions and recovery during this critical developmental period and highlighting the need for enhanced management in this popula- tion. given the unique cascade of series of adaptive neurometa- bolic responses that take place in the brain following a head injury, optimizing treatment strategies—particularly during the critical adolescent brain developmental period—are needed. we review research evidence for potential benefits of nutrition as medicine in src and explore the contention of how nutrient in- adequacies affect such. according to this concept, neurometabolic consequences contribute to the development and persistence of post-concussive symptoms after src in some youth. we hypoth- esize that a) nutrition supplementation initiated immediately post- src represents a key component of rehabilitation with particular relevance in adolescents; and b) the poorer outcomes in females can be explained at least in part by greater inadequacies of nutri- ents in females relative to their male counterparts prior to sustain- ing a concussion. addition of nutrition as medicine to guidelines that emphasizes prompt supplementation is encouraged. a key pathophysiological phenomenon after a mechanical trauma to the brain is the complex cascade of neurochemical and neurometabolic events and consequent alterations in cerebral me- tabolism and blood flow, which may result in an energy crisis. , , two major alterations of glucose metabolism have been described: hyperglycolysis (and thus hyperglycemia) and oxidative dysfunc- tion (rampant activation of the inflammatory cascade). particular- ly, glutamate release from damaged cells leads to excitotoxicity, mounting an adverse response including the influx of ca + through glutamate receptors and voltage-gated ca + channels. , this in turn activates calcium-dependent proteases, such as calpains and lipases, which degrade membrane phospholipids, leading to the release of fatty acids. , , fatty acids (primarily arachidonic acid, the precursor of eicosanoids) are released from membranes and transformed into pro-inflammatory eicosanoids which exacerbate tissue injury by inducing vasoconstriction and platelet aggrega- tion, increased inflammation, and production of free radicals. within hours, there is also activation of complex dynamics of local cytokine and chemokine production. concomitantly, synthesis and release of anti-inflammatory factors such as the ω- polyunsatu- rated fatty acid (pufa) docosahexanoic acid (dha) are oxidized as fuel; thus, their role as structural components of membranes needed for cellular repairs is attenuated. the stress response is also known to induce gluconeogenesis and glycogenolysis, as well as the release of cortisol, further exac- erbating hyperglycemia and as a consequence augmenting cellular injury and secondary response. , , increased glutamate release and subsequent increased lactate production (and acidosis) are also associated with hyperglycemia. although a general characteriza- tion of the post-concussion adaptive responses exists, each concus- sion is unique, with developmental stage, sex and race differences observed in addition to brain region that was affected. we contend supplementation-specific dietary components alone and/or in combination have the potential to positively influence and to effectively treat the neuroinflammation associated with src. despite the understood role of the brain as the primary regu- lator of metabolism and the well-established metabolic impair- ments evoked after a concussion, nutrition is often ignored as a core complement to the recovery and rehabilitation process. here- in, we will identify deficiencies and/or inadequacies in nutrients post-concussion and provide support for potential exacerbation of injury and delayed recovery due to inadequate intake of nutrients prior to sustaining an src. specifically, among high school adolescents, src incidence has more than doubled from to , with recent estimates at approximately per athletes. rapid changes in brain or- ganization and development occur in adolescence, with profound reshaping of the prefrontal, parietal temporal-associated, and sen- sorimotor cortex prior to achieving adult-like connections by the mid- s. these areas, which do not fully mature until approxi- mately years of age, play a substantial role in executive func- tions such as problem solving and decision making. paralleling the structural changes are changes in cerebral glucose metabolism and cerebral blood flow. although post-concussed adolescent athletes often display no gross neural pathologies and have no immediate threat to their life, profound biochemical changes induced by injury in immature, highly-sensitive structures (e.g., the prefrontal cortex, hippocam- pus, hypothalamus) during this critical developmental stage can increase risk for several neuropsychiatric conditions, with far- reaching acute and chronic systemic effects. brain injury, of any severity, in the developing brain is complicated by ongoing cer- ebral maturation. of crucial importance in prognosis is the rapid increase in reactive stressors that heighten the metabolic demand on the brain. concussion induces inflammatory sensory stimulus that is preferentially transmitted to brainstem and specific hypothalamic nuclei which have direct connection to the hypothalamic paraven- tricular nucleus. specifically, activation of the inflammatory cas- cade, increased protein catabolism and altered energy metabolism have been well-established as inducing long-term adverse effects on the developing brain via altered neuroendocrine and physiologic processes. increased inflammation markedly affects neurotrans- mission within emotional regulatory brain circuits and can dys- regulate the hypothalamic-pituitary-adrenal axis. consequently, a strategy that enhances the brain’s response against harmful effects of inflammation and protein catabolism may potentiate damaging post-concussive effects in the stress-sensitive brain structures of the adolescent athlete. energy (macronutrient) and micronutrient (vitamin and min- eral) needs during adolescence are relatively high, as compared to in adulthood. while few studies have evaluated the dietary pat- terns of young athletes, particularly those participating in sport at the community/high school level and especially based on sex, race/ethnicity and socioeconomic status, it has been reported that dietary intakes in young athletes are reportedly superior to their non-athletic counterparts. – however, the increased demands of competition in the context of growth and development imply that the potential consequences of a deficiency may be more detrimen- tal in athletes. to get a better understanding of how certain nutrients may aid in the treatment of src, it is important to understand the neuromo- lecular cascade that occurs in the brain after a concussion, which has been best studied in animal tbi models. observational data consistently show that during the initial post-concussed state, ener- gy and protein deficits are apparent and are associated with worse outcomes. insufficient micronutrient intakes in the general popula- tion adolescent population can profoundly impact energy and ma- cronutrient metabolism, particularly for the b vitamins, vitamin d doi: . /erhm. . | volume issue , december casazza k. et al: nutrition in sports-related concussionexplor res hypothesis med and iron. in this review, we will demonstrate specific nutrients can be utilized for post-src supplementation based on their putative roles in the mechanisms of brain injury. energy crisis in an effort to restore cellular homeostasis and membrane potential, hyperactive adaptive responses of adenosine triphosphate (atp)- requiring ion pumps occur, causing hyperglycolysis and concomi- tant low intracellular energy reserves. in the context of reduced cerebral blood flow (due to edema), a mismatch between energy supply and demand ensues. disturbance in intracellular calcium flux, manifests into sequestration of calcium into mitochondria, which can then result in mitochondrial dysfunction, exacerbate oxidative metabolism and worsen the cellular energy crisis. af- ter an initial period of hyperglycolysis and metabolic uncoupling, glucose metabolic rates go into a state of hypoglycolysis. energy crisis is associated with behavioral impairments in spatial learning as well as altered gene expression and enzyme/transporter regula- tion, which may underlie long-term sequelae. glucose the post-injury energy crisis and glucose metabolic disturbance is exacerbated by increased flux of glucose through the pentose phos- phate pathway and inhibition of key glycolytic enzymes. emerg- ing data suggest that under these post-brain injury conditions of impaired glycolytic metabolism, glucose may not be the best fuel for the injured brain. – while the neuroprotective benefit of a ketogenic diet after src has yet to be investigated systematically, some studies in animals have demonstrated improvement in contu- sion volume and behavioral outcomes with a ketogenic diet. protein protein and its amino acid building blocks play critical roles in various metabolic and energetic pathways. as a substantial amino acid pool does not exist, protein homeostasis depends upon a func- tioning system of protein degradation and recycling. the effects of energy crisis trigger protease activation and apoptotic cell death, limiting protein synthesis. further, the profound increases in rest- ing energy expenditure in the injured brain and associated negative nitrogen balance induce transient protein inadequacy. the lack of availability of essential amino acids due to sec- ondary inflammatory cellular damage not only adversely affects cell survival and function in the injured brain but can also induce system-wide detrimental effects. increased protein catabolism is observed within hours of injury, and low levels of branched- chain amino acids (bcaas), histidine and methionine have been shown to persist months after injury. – protein catabolism and subsequent hypoalbuminemia can also disrupt mineral availability (e.g., zinc, iron), further exacerbating oxidative stress. restora- tion of protein and nitrogen balance may reduce oxidative stress secondary to concussive injury and facilitate recovery. beyond protein synthesis, essential amino acids, provided only through the diet, serve as a substrate for key molecules. for exam- ple, bcaas are integral in overall energy metabolism, regulation of gluconeogenesis and protein synthesis, as well as functioning as a major source of nitrogen for glutamine and nitric oxide pro- duction. as such, inadequate protein and bcaa availability in the post-concussed state impacts a number of biological processes, including cytoprotection and gene expression. while it has been suggested that protein inadequacy may be related to a decreased overall intake following a brain injury, a study of healthy fasted volunteers versus individuals with a traumatic brain injury, in which both groups had not eaten for hours demonstrated signifi- cantly greater protein catabolism in tbi. given that the adolescent athlete requires approximately . – . g/protein/day to maintain lean body mass and normal protein synthesis, protein supplemen- tation post-concussion is a reasonable strategy to improve out- comes following a src. bcaas in the brain, bcaas serve as important metabolic precursors for synthesis of proteins and neurotransmitters, including dopamine, serotonin and norepinephrine. following brain injury, bcaas become readily oxidized, potentially contributing to the metabolic crisis post-src. lower bcaas in tbi patients relative to controls has been observed in various studies. – , bcaa supplementa- tion in rodents has been shown to restore net synaptic efficiency and hippocampal function and consequent restoration of cognitive function. – creatine creatine is well-known for its use in athletes for purported benefits regarding muscle hypertrophy. however, as a biochemical effect in the central nervous system (cns) via phosphorylation of adeno- sine diphosphate (adp) to make atp, and theoretically decreasing hyperglycolysis and oxidative damage, creatine has emerged as a potential treatment of concussions. the primary role of creatine in the body involves energy homeostasis via maintenance of con- stant cellular atp levels in tissues with highly fluctuating energy demands (i.e. muscle and brain). , the creatine-atp energy system enables rapid, efficient atp regeneration in the absence of oxygen. the system decreases glycolysis and the consequential synthesis and accumulation of lactic acid. assessment of creatine pre- and post-concussion by magnetic resonance spectroscopy has shown decreased levels in the brain after sustaining a concussion. a potential antioxidant effect has also been hypothesized. in animal models, creatine supplementa- tion pre-tbi has demonstrated a neuroprotective effect on mito- chondrial function and secondary injury. human studies, though limited to severe tbi, have shown increased cognitive function and decreased headache and dizziness. dha pufas, specifically ω- , are essential for the rapid neurogenesis during brain development as well as neuroprotection across the lifespan. dietary depletion has been shown across species to impair structural and neuronal development and function in early life. in addition to the structural role, ω- pufas, particularly dha, are involved in multiple brain functions, including cell membrane fluidity, receptor affinity and modulation of signal transduction molecules. – the mechanisms involved in ω- pufas’ neuroprotection over the life course (including injury) include decreased neuroinflammation and oxidative stress, neuro- trophic support and activation of cell survival pathways. the level of total ω- pufas in plasma is inversely correlated with the level of pro-inflammatory markers (il- , tnfα, il- and c-reactive doi: . /erhm. . | volume issue , december casazza k. et al: nutrition in sports-related concussion explor res hypothesis med protein (crp)) and the ω- /ω- pufa ratio is negatively corre- lated with il- anti-inflammatory marker. ω- pufas are synthesized through desaturation and elongation reactions from their precursor, an -carbon-atom fatty acid, alpha- linolenic acid (ala), which is available in the diet. however, the ω- pufa required by the cns is essential, and not produced de novo in mammals. under pathological conditions, including src, phospholipases rapidly release pufas from membranes. the accumulation of free fatty acids activates inflammatory path- ways through cell-specific receptors and activation of protein kinases. in turn, a large number of lipid mediators augment oxi- dative stress and induce mitochondrial dysfunction. dha, the primary structural ω- pufa present in the brain, preferentially accumulates in the frontal cortex and hippocampus, constituting up to % of the ω- pufas in the brain. it is converted to ox- ylipin intermediates, thus rendering high cns demands for dha unattainable. the unavailability of dha in such instances as tbi, affects physical properties of membranes via alteration of transmembrane enzymes and binder receptor proteins as well as neurotransmitter synthesis and release. substantial evidence for animal studies investigating ω- pufa supplementation before or after tbi supports a protective effect of ω- pufa on the brain by limiting structural damage to the axon and attenuating events inducing neuronal apoptosis. while an adequate supply of dha is recommended, worldwide consumption is low, with most adolescents having an inadequate intake of ω- pufa. dietary sources of dha are limited, with cold-water algae being the primary producers of dha and epa. fish are also rich sources of dha due to a diet consisting of algae. dietary intake of the essential fa and precursor to dha α-linolenic acid (ala; : n- ) is generally much higher. , although ala can be metabolically converted to dha, the conversion rate is low. further, diets higher in ala seem to limit the conversion rate by increasing the rate of ala oxidation, and contemporary food manufacturing has dramatically altered the ω- /ω- pufa ratio in the western diet. there has been an increase in ω- pufa intake and concomitant decrease in ω- pufa intake. in humans, dietary supplementation with dha against acute and chronic inflammation within the cns was first reported as case studies (i.e. lone survivor of the sago mine disaster, tbi after a motor vehicle accident in an adolescent), in which recovery ap- peared to be associated with supplementation of pufas. supple- mentation of dha has been shown to reduce glutamate-induced excitotoxicity and both axonal and neuronal injury through mod- ulation of ion channels. in embryonic hippocampal and cortical neuron cultures, supplementation with dha has been shown to increase neurite number and length. in rodent models, dha sup- plementation post-moderate tbi was shown to decrease number of axon apoptosis and to increase hippocampal neurons as well as decrease pro-inflammatory cytokines and markers of oxidative stress. – rodent models have also been fairly consistent in demonstrat- ing a beneficial effect of dha supplementation through multiple signaling pathways in brain injury, spinal cord injury and cardiac ischemia-reperfusion. specifically in models of head injury, prophylactic supplementation with dha attenuates white matter damage, as evidenced by fewer beta amyloid precursor-positive axons, enhanced preservation of myelin, and protection of neu- rofilament morphology. , – further, dha supplementation has been shown to allay glutamate cytotoxicity, suppress mitochon- drial dysfunction and the eventual development oxidative stress, decrease calcium influx, and down-regulate α-amino- -hydroxy- -methyl- -isoxazolepropionic acid receptor subunits. while the preservation of white matter undoubtedly aids in maintaining neurocognitive function following injury, the blunting of injury- induced reductions in molecular elements important for learning may also play a role. while the precise mechanism by which dha confers a neuro- protective effect is multifaceted and not completely understood, it likely includes a series of mutual mechanisms that enhance the structural integrity of neurons, thereby diminishing the secondary pathological sequelae (i.e. neuroinflammation, impaired energy metabolism, glutamate release) that occurs post-injury. in summa- ry, ω- pufas have been shown to address several of the hallmark pathologic features of brain injury, such as excitotoxicity, oxida- tive stress, and inflammation. a dose-dependent relationship ex- ists, whereby plasma phospholipid dha concentrations increase up to a dosage of approximately g/day, after which any further increase in dose negligibly increases plasma phospholipid concen- tration. however, despite substantial evidence from rodent mod- els of tbi, human-based studies examining the neuroprotective effects of dha have been limited to clinical case studies. vitamin d vitamin d, most notably studied for its role in calcium homeosta- sis, has emerged as a significant contributor to a broad range of physiologic activities, including muscle function, metabolic con- trol and immune modulation. more recently, it has been identified as a substance with substantial involvement in brain development, health and function. the vitamin d receptor (vdr) protein is reportedly expressed broadly in the brain, including the neurons and glial cells. further, , (oh)d appears to influence neuronal cell differentiation and exert neuroprotective actions against cyto- toxicity. vitamin d deficiency exacerbates inflammatory response and cell death. the role of vitamin d supplementation post-tbi and/or inves- tigation of the role of vitamin d deficiency on outcomes following tbi was recently reviewed. a significant reduction in phospho- rylation of nuclear factors, which in turn stimulate downstream genes involved in the inflammatory cascade, were shown to be reduced by vitamin d treatment post-tbi. in separate studies, tang et al. and cekic et al. demonstrated that vitamin d defi- ciency was associated with more adverse pathophysiological out- comes following tbi. of note, an estimated % of adolescents have insufficient vitamin d. further, in a clinical sample, hua et al. observed improved functional outcomes with vitamin d sup- plementation post-tbi. despite its emergence as an integral cofactor in brain health, there have been no clinical trials to assess the efficacy of vitamin d as a treatment for mild tbi. studies conducted in other aspects of neurocognition (i.e. stroke, alzheimer’s, dementia) have es- tablished an association with vitamin d insufficiency and suggest prevention of vitamin d deficiency may serve a valuable role as a neuroprotective therapy. , , thiamin restoration of energy metabolism and membrane homeostasis may reduce oxidative stress secondary to concussive injury and facilitate recovery. “much of the role in neuronal excitability has been derived from the evaluation of effects of alcohol on thiamine diphosphate in the context of the brain and wernike-korsakoff syndrome. the synergistic effects of thiamin deficiency and alco- hol-induced neurotoxicity from excessive glutamate release elicit acute cerebral damage and subsequent irreversible neuronal dam- doi: . /erhm. . | volume issue , december casazza k. et al: nutrition in sports-related concussionexplor res hypothesis med age.” it is biochemically analogous that, in tbi, changes due to inadequate thiamin primarily involve decreased activity of the enzymes, a process that leads to energy deficits as a consequence of impairment of the tricarboxylic acid (tca) cycle which can ultimately lead to neuronal apoptosis. altered energy metabolism, secondary to unavailability of thia- min co-factors, also results in the development of lactic acidosis in response to impaired tca cycle activity. this acidosis can con- tribute to cytotoxic brain edema, a contributor to excitotoxicity, as well as a net increase in free radical production and oxidative stress along with development of inflammatory processes. because thiamin represents an integral cofactor involved in processes asso- ciated with the metabolism of lipids, glucose, amino acids and neu- rotransmitters, inadequate levels can lead to severe complications in the nervous system. diminished availability of thiamin in the brain profoundly limits enzyme activity, leading to alterations in mitochondrial activity, impairment of oxidative metabolism, de- creased energy status, and exacerbation of secondary injury path- ways. accumulating evidence indicates that deficiency in thiamin in- duces mild chronic impairment of oxidative metabolism of micro- glia, astrocytes and endothelial cells, as well as abnormalities of cerebral glucose metabolism. this in turn, increases neuronal apo- ptosis. in animal models, thiamin inadequacy is associated with pathology of brain injury. compromised mitochondrial function, is also apparent and leads to increased free radical production that contributes to neuronal dysfunction and apoptosis. further, inad- equate thiamin dysregulates glucose metabolism, which induces alterations in cerebral blood flow, along with compensatory stimu- lation of lactic acidosis, which contributes to impairments in the blood–brain barrier (bbb) breakdown. bbb disruption then leads to decreased fatty acid synthesis, which itself can lead to demyeli- nation and decreased nucleic acid synthesis. niacin niacin (nicotinamide; vitamin b ) is regarded as a broad-spectrum neuroprotectant. its role is as a precursor for nad+, the coenzyme commonly known for its role in the electron transport chain, al- lowing for the production of atp. activation of microglia in tbi causes up-regulation of nicotinamide adenine dinucleotide phos- phate (nadph) oxidase and activation of the inflammatory cas- cade and consequent cytotoxicity. nicotinamide supplementation has been shown to attenuate secondary damage in tbi. the mechanistic underpinnings of the purported benefits have been linked to increased bioavailability of atp to cells following the neural insult, an inhibition of injury-induced poly-adenosine diphosphate-ribose polymerase- (parp- ) and sirtuin- activa- tion, both of which act to deplete nad+ and reductions in apoptot- ic and necrotic death. the decrease in nad+ is that which is often linked to apoptosis. nad+ theoretically provides cytoprotection through pathways that involve poly(adp-ribose) polymerase, akt, mitochondrial membrane potential and cysteine protease activity, and prevents apoptosis by maintaining dna integrity as well as protects against microglial activation with subsequent phagocytic destruction of cells. niacin is also actively involved in redox re- actions, modulates the mitochondrial permeability transition pore and replenishes nicotinamide adenine dinucleotide phosphate lev- els with resultant increases in glutathione reducing free radicals produced following injury. direct and indirect inhibition of parp- , has also been re- ported to have beneficial effects on tissue and behavior following injury, while activation of the parp- pathway has been shown to be detrimental. in clinical trials, nicotinamide supplementation has been reported to significantly reduce injury volume, decrease glial fibrillary acidic protein activation, reduce the blood brain barrier breach, reduce acute edema, reduce behavioral impair- ments, and improve outcomes. additionally, niacin treatment has been shown to counteract gene expression changes due to tbi via down-regulation of genes activated by injury. iron the increased need for iron in adolescents to support growth, ex- pansion of red blood cell volume and addition of lean body mass have been long appreciated. iron is important to maintain adequate hemoglobin concentrations as well as total iron stores during growth. furthermore, it is well documented that iron deficiency anemia can lead to fatigue, performance, and learning ability. , brain injury is associated with iron deficiency and has been shown to exacerbate symptoms of fatigue and muscle weakness. in turn, iron deficiency impairs erythropoiesis and enhances erypto- sis, resulting in anemia. improper distribution of iron within the body has been suggested to contribute to the iron deficit in the erythropoietic system and iron overload in the substantia nigra in neuroinflammatory conditions, such as parkinson’s disease. moreover, iron modulates dopamine synthesis and re-uptake (as does vitamin c at the level of dopamine β-hydroxylase); tyros- ine hydroxylase, an enzyme responsible for dopamine synthesis, is iron-dependent. iron deficiency has also been shown to impair dopamine re-uptake in rodents. sex differences in concussion outcomes although arguably confounded by across-sport participation num- bers and inconsistencies in baseline measures, sex differences in both the incidence and outcomes of concussions have been re- ported. , collectively, in evaluations of sports played by both sexes (e.g., soccer, baseball/softball, basketball), concussions rep- resented a greater proportion of total injuries in females, with a greater number and severity of symptoms, poorer outcomes, and longer duration to recover. , – the mechanisms underlying this sex difference are unclear, and may in part relate to biological differences that are compounded by cultural distinctions in how concussions are reported and managed. proposed differences in neck strength, movement biomechanics and symptom reporting prevalence in females compared with males have been suggested. however, we contend dietary factors likely play a substantial role. nutrition parameters in adolescent athletes are sparse, with the majority focused at the college level. in female collegiate athletes, sato et al. reported blood thiamin concentration decreased sig- nificantly during training, with a greater magnitude in females. iron balance of the female adolescent athletes, beyond the tradi- tional explanation of dietary intake/iron loss balance, has emerged as a significant concern. a recent study among collegiate athletes observed . % iron deficiency anemia and . % iron deficien- cy without anemia in females, as compared to . % and . %, re- spectively, in males. further, sandstrom and colleagues recently reported lower serum iron and elevated hepcidin in the athlete group relative to that in the non-athlete group. impaired iron balance also influences metabolic fuel availabil- ity and associated growth hormone (gh) function. in addition, inadequate iron suppresses ghrelin concentrations. moreover, iron deficiency coupled with impaired gh function observed in src may reduce free fatty acid availability to further lower serum glu- doi: . /erhm. . | volume issue , december casazza k. et al: nutrition in sports-related concussion explor res hypothesis med cose concentrations and enhance muscle protein degradation. key points ● although impaired glucose metabolism is characteristics of src under post-brain injury conditions of impaired gly- colytic metabolism, glucose may not be the best fuel for the injured brain. ● protein is essential for normal brain energy metabolism. inadequacy leads to a wide-ranging cascade of events, many of which overlap, and may interact, ultimately re- sulting in neuronal apoptosis. ● given the consistent reporting of depressed endogenous levels and absence of adverse outcomes from supplemen- tation of bcaas, supplementing appears feasible. ● a potential synergistic effect of creatine supplementation post-src on muscular and cognitive function warrants in- vestigation. ● animals supplemented with ω- pufas consistently ex- hibit enhanced resilience to tbi, with functional outcomes mirroring those biological indicators of injury, even fol- lowing multiple mild tbis, similar to that which would be observed in repetitive sports-related concussive injuries over a lifetime of play. ● thiamin is essential for normal brain energy metabolism. inadequacy leads to a wide-ranging cascade of events, many of which overlap, and may interact, but ultimately result in neuronal apoptosis. ● evidence for improved outcomes using vitamin d supple- mentation, particularly in those who are deficient, lends credence to the potential for use to limit complications. future directions/prospective/prediction because of the complex and multifactorial nature of the adverse effects of the tbi process, identifying a single strategy that will be sufficient to address the sequelae of physical, behavioral and cognitive manifestations is unlikely. however, capitalizing on the multitude of beneficial effects of dietary components represents a cost- effective strategy for reducing both the cognitive and behav- ioral deficits. further study in humans is needed to demonstrate the utility of post-concussive supplementation for cognitive and behavioral recovery after mild tbi. while nutritional intervention has been shown to change meta- bolic function in cell culture, brain function in animal models of mild tbi as well as other neurological populations, some impor- tant unanswered questions remain. for example, with similar se- verity of injury, why are complications more severe among some individuals? will baseline nutritional status prior to concussion in- fluence response to treatment? we hypothesize that the differences in response to and recovery from concussion include physiologic as well as environmental factors. though improving treatment post-concussion has received recent attention, lack of baseline data describing the underlying processes limits identification of a successful approach to improve long-term outcomes and elucidate differences in complications be- tween sexes as well as emerging differences among racial groups. future studies will require a pre-participation baseline assessment in student athletes. given the intense consequences of lack of fuel availability for recovery of the injured brain, with little informa- tion on the nutritional needs in the still developing adolescent brain, evaluation of baseline nutritional status (i.e. energy metabo- lism, essential nutrient adequacy) is required. conclusions treatment strategies of adolescents sustaining an src often in- clude principles, guidelines and recommendations developed for adults. a number of unique concerns remain with respect to the developing brain, including the greater susceptibility to long-term sequelae. the sudden and profound “neurotoxicity” induced by biochemical changes following src manifest energy crisis, mi- tochondrial dysfunction, activation of the inflammatory cascade, and metabolic vulnerability to nutritional inadequacies. prompt initiation of nutritive therapy represents an integral facets of con- cussion management. concussive outcomes may differ in terms of the precise underlying biochemical anomalies and functional impairments, and by sex. current best-practice guidelines recommend a period of cogni- tive and physical rest, followed by a gradual return to school and activity, with little (if any) focus on restoring metabolic sufficien- cy. the concept of physical and cognitive rest as the cornerstone of concussion management asserts that during the acute ( – days, which are arguable longer in youth) post-injury period of increased metabolic demand and limited atp reserves, non-essential activity draws oxygen and glycogen away from injured neurons. this “shut down” or “dark closet” approach following concussion ignores nu- trition as a key component of therapy. nutrient adequacy is essential for compensatory metabolic reg- ulation, yet is often overlooked as a critical component to metabol- ic recovery after concussion. sufficiency of endogenous substrates is a strong determinant of recovery and rehabilitation; thus, nutri- tion supplementation represents a viable and valuable component of treatment, particularly in adolescents post-src. conflict of interest the authors have no conflict of interest(s) related to this publica- tion. author contributions conception and/or the acquisition of literature reviewed (kc, es), interpretation of the overall concepts (kc, es), drafting of the manuscript (kc, es), revising or questioning its intellectual content (kc, es), and giving approval of the final version of the manuscript for publication (kc, es). references [ ] harmon kg, drezner ja, gammons m, guskiewicz km, halstead m, herring sa, et al. american medical society for sports medicine posi- tion statement: concussion in sport. br j sports med ; ( ): – . doi: . /bjsports- - . 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[ ] tang h, hua f, wang j, yousuf s, atif f, sayeed i, et al. progester- one and vitamin d combination therapy modulates inflammatory response after traumatic brain injury. brain inj : – . doi: . / . . . [ ] tang h, hua f, wang j, et al. progesterone and vitamin d: improve- ment after traumatic brain injury in middle-aged rats. horm behav ; ( ): – . [ ] cekic m, sayeed i, stein dg. combination treatment with progester- one and vitamin d hormone may be more effective than monother- apy for nervous system injury and disease. front neuroendocrinol ; ( ): – . doi: . /j.yfrne. . . . [ ] pfeiffer cm, sternberg mr, schleicher rl, haynes bm, rybak me, pirkle jl. the cdc’s second national report on biochemical indica- tors of diet and nutrition in the u.s. population is a valuable tool for researchers and policy makers. j nutr ; ( ): s– s. doi: . /jn. . . [ ] hua f, reiss ji, tang h, wang j, fowler x, sayeed i, et al. proges- terone and low-dose vitamin d hormone treatment enhances sparing of memory following traumatic brain injury. horm behav ; ( ): – . doi: . /j.yhbeh. . . . [ ] witham md, dove fj, sugden ja, doney as, struthers ad. the ef- fect of vitamin d replacement on markers of vascular health in stroke patients - a randomised controlled trial. nutr metab cardiovasc dis ; ( ): – . doi: . /j.numecd. . . . [ ] berridge mj. vitamin d cell signalling in health and disease. bio- chem biophys res commun ; ( ): – . doi: . /j.bbrc. . . . [ ] thomson ad, guerrini i, marshall ej. the evolution and treatment of korsakoff’s syndrome: out of sight, out of mind? neuropsychol rev ; ( ): – . doi: . /s - - -z. [ ] jhala ss, hazell as. modeling neurodegenerative disease pathophysi- ology in thiamine deficiency: consequences of impaired oxidative me- tabolism. neurochem int ; ( ): – . doi: . /j.neuint. . . . [ ] liu d, ke z, luo j. thiamine deficiency and neurodegeneration: the interplay among oxidative stress, endoplasmic reticulum stress, and autophagy. mol neurobiol ; ( ): – . doi: . / s - - - . [ ] shear da, dixon ce, bramlett hm, mondello s, dietrich wd, deng- bryant y, et al. nicotinamide treatment in traumatic brain injury: operation brain trauma therapy. j neurotrauma ; ( ): – . doi: . /neu. . . [ ] maiese k, chong zz. nicotinamide: necessary nutrient emerges as a novel cytoprotectant for the brain. trends pharmacol sci ; ( ): – . doi: . /s - ( ) - . [ ] kristian t, balan i, schuh r, onken m. mitochondrial dysfunction and nicotinamide dinucleotide catabolism as mechanisms of cell death and promising targets for neuroprotection. j neurosci res ; ( ): – . doi: . /jnr. . [ ] buratti p, gammella e, rybinska i, cairo g, recalcati s. recent ad- vances in iron metabolism: relevance for health, exercise, and perfor- mance. med sci sports exerc ; ( ): – . doi: . / mss. . [ ] scott sp, murray-kolb le. iron status is associated with performance on executive functioning tasks in nonanemic young women. j nutr ; ( ): – . doi: . /jn. . . [ ] winter we, bazydlo la, harris ns. the molecular biology of human iron metabolism. lab med ; ( ): – . doi: . /lmf- s gimxnwhmm. [ ] hong ct, huang yh, liu hy, chiou hy, chan l, chien ln. newly diag- nosed anemia increases risk of parkinson’s disease: a population- based cohort study. sci rep ; : . doi: . /srep . [ ] nelson c, erikson k, pinero dj, beard jl. in vivo dopamine metabolism is altered in iron-deficient anemic rats. j nutr ; ( ): – . [ ] iverson gl, gardner aj, terry dp, ponsford jl, sills ak, broshek dk, et al. predictors of clinical recovery from concussion: a systematic review. br j sports med ; ( ): – . doi: . /bjs- ports- - . [ ] gardner a, iverson gl, levi cr, schofield pw, kay-lambkin f, kohler rm, et al. a systematic review of concussion in rugby league. br j sports med ; ( ): – . doi: . /bjs- ports- - . [ ] black am, sergio le, macpherson ak. the epidemiology of concus- sions: number and nature of concussions and time to recovery among female and male canadian varsity athletes to . clin j sport med ; ( ): – . doi: . /jsm. . [ ] covassin t, elbin rj, bleecker a, lipchik a, kontos ap. are there dif- ferences in neurocognitive function and symptoms between male and female soccer players after concussions? am j sports med ; ( ): – . doi: . / . [ ] eckner jt, oh yk, joshi ms, richardson jk, ashton-miller ja. effect of neck muscle strength and anticipatory cervical muscle activation on the kinematic response of the head to impulsive loads. am j sports med ; ( ): – . doi: . / . [ ] kroshus e, baugh cm, stein cj, austin sb, calzo jp. concussion reporting, sex, and conformity to traditional gender norms in young adults. j adolesc ; : – . doi: . /j.adoles- cence. . . . [ ] ono ke. sex-based differences as a predictor of recovery trajectories in young athletes after a sports-related concussion: response. am j sports med ; ( ):np . doi: . / . [ ] reynolds bb, patrie j, henry ej, goodkin hp, broshek dk, winter- mark m, et al. effects of sex and event type on head impact in col- legiate soccer. orthop j sports med ; ( ): . doi: . / . [ ] zuckerman sl, apple rp, odom mj, lee ym, solomon gs, sills ak. effect of sex on symptoms and return to baseline in sport-related concussion. j neurosurg pediatr ; ( ): – . doi: . / . .peds . [ ] sato a, shimoyama y, ishikawa t, murayama n. dietary thiamin and riboflavin intake and blood thiamin and riboflavin concentrations in college swimmers undergoing intensive training. int j sport nutr ex- erc metab ; ( ): – . doi: . /ijsnem. . . . [ ] parks rb, hetzel sj, brooks ma. iron deficiency and anemia among collegiate athletes: a retrospective chart review. med sci sports ex- erc ; ( ): – . doi: . /mss. . [ ] sandstrom g, rodjer s, jacobsson s, nelson d, borjesson m. in- creased level of serum hepcidin in female adolescent athletes. clin j sport med . doi: . /jsm. . [ ] petkus dl, murray-kolb le, de souza mj. the unexplored crossroads of the female athlete triad and iron deficiency: a narrative review. sports med ; ( ): – . doi: . /s - - - . 	abstract
 	introduction
 	energy crisis
 	glucose
 	protein
 	bcaas
 	creatine
 	dha
 	vitamin d
 	thiamin
 	niacin
 	iron
 	sex differences in concussion outcomes
 	key points
 	future directions/prospective/prediction
 	conclusions
 	conflict of interest
 	author contributions
 	references
 -februlary , --olume l , number american association for the advancement of science science serves its readers as a forum for the pre- sentation and discussion of important issues related to the advancement of science, including the presentation of minority or conflicting points of view, rather than by publishing only material on which a consensus has been reached. accordingly, all articles published in science- including editorials, news and comment, and book re- views-are signed and reflect the individual views of the authors and not official points of view adopted by the aaas or the institutions with which the authors are affil- iated. editorial board ward goodenough donald kennedy clifford grobstein neal e. miller h. s. gutowsky raymond h. thompson n. bruce hannay richard e. balzhiser frank w. putnam james f. crow maxine singer hans landsberg paul e. waggoner edward ney f. carl willenbrock editorial staff editor philip h. abelson publisher business manager william d. carey hans nussbaum managing editor: robert v. ormes assistant editors: ellen e. murphy, john e. ringle assistant to the editors: richard semiklose news and comment: john walsh, editor; philip m. boffey, luther j. carter, barbara j. culliton, constance holden, deborah shapley, nicholas wade. editorial assistant, scherraine mack research news: allen l. hammond, editor; gina bari kolata, jean l. marx, thomas h. maugh ii, william d. metz, arthur l. robinson. editorialas- sistant, fannie groom book reviews: katherine livingston, janet kegg cover editor: grayce finger editorial assistants: john baker, isabella boul- din, eleanore bjtz, mary dorfman, sylvia eber- hart, judith givelber, caitilin gordon, corrine harris, nancy hartnagel, oliver heatwole, christine karlik, ruth kulstad, margaret lloyd, jean rockwood, leah ryan, lois schmitt, ya li swigart, eleanor warner guide to scientific instruments: richard sommer membership recruitment: gwendolyn huddle; subscription records and member records: ann rag- land advertising representatives director production manager earl j. scherago margaret sterling advertising sales manager: richard l. charles sales: new york, n.y. : herbert l. burklund, i w. st. 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( - - ) editorial correspondence: massachu- setts ave., nw, washington, d.c. . phones: (area code ) central office: - ; book re- views: - ; business office: - ; circulation: - ; guide to scientific instruments: - ; news and comment: - ; reprints and per- missions: - ; research news: - ; review- ing: - . cable: advancesci, washington. copies of "instructions for contributors" can beobtained from the editorial office. see also page xi, science, march . advertising correspondence: room , w. st., new york, n.y. . phone: - pe- . scie nce learning about energy the hard way for more than a decade it has been obvious that the united states is destined to face enormous adjustments in its use of energy. the difficulties and costs of finding new oil and natural gas have been climbing rapidly and it is clear that potential discoveries are limited. the embargo of - should have led to vigorous action, but it was quickly ignored. by mid-march the acute stage of the current energy shortage will have passed. because supplies of foreign petroleum are available, a major disaster has been avoided. a huge shortfall has been in part made good by record imports of oil. the united states is fortunate in another aspect. although generating equipment was taxed to the utmost, the electrical utili- ties were able to avoid massive power shutdowns. and so, although domestic sources of oil and gas continue to decline, the united states will luck through another energy crisis. but other crises will come, and will probably be more severe, for even with action now, many years must elapse before the gap between domestic production and con- sumption of energy can be made to decrease substantially. in principle, conservation is the solution, with a goal of reducing energy consumption to half its present level. however, the record of the past years provides little basis for hope that energy consumption can easily be cut. industry has already made most of the simple moves such as fixing steam leaks. those homeowners who are willing to turn down the thermo- stat have already done so. to achieve really substantial economies will require investment of as much as a thousand billion dollars or more. even were major changes to begin now, a decade or more would have to pass before their effects would be largely felt. still a beginning must be made, but that will evidently require more incentives than have hitherto been supplied. the people must come to understand and believe that the various forms of energy-especially those based on oil and natural gas-are going to become steadily more scarce and much more expensive. examples of incentives would be huge taxes on gasoline and heavy autos. conversations with people in industry indicate that new energy-saving installations would be built if funds were available at low interest rates. such construction would employ many workers. much of the energy that is consumed by industry is utilized for process heat. in principle coal rather than oil or natural gas could be used, and this substitution could be the fastest means for freeing supplies of natural gas and oil. however, in general, capital expenditures would be involved, and again financial incentives would speed the process. overall, the amount of energy moved in gas pipelines is about three times that transmitted electrically. for home heating there is no easy domestic substitute for natural gas. to replace methane by electricity in homes alone would require an investment in generating plants and heat pumps amounting to several hundreds of billions of dollars. solar heating would also involve, enormous investment. domestic supplies of both oil and gas could be increased. for example, additional amounts of methane might be obtained from fermentation of biomass, from disposal of organic matter in sanitary landfills, from gases associated with coal, from brown shales of the appalachian basin and elsewhere, from the low-porosity rocks of the uinta and other western basins, from the geopressured zones of the gulf coast, and from alaska. at some time in the future there will be synthetic methane from coal. probably most practical is natural gas to be discovered by conventional drilling. methane from all of these sources will be expensive. the united states apparently learned nothing from the - em- bargo. perhaps a second lesson will be more effective. if not, other lessons will come and they will be more harsh.-philip h. abelson o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ learning about energy the hard way philip h. abelson doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the is a registered trademark of aaas.sciencescience, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for the advancement ofscience by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ oil-wells blocked to prevent war damage environmental conservation may provide a means of testing the theory by molecular biological analysis, he said. 'the peculiarities of these bacteria that we discovered strongly suggest that they may be of great value for tracing early biochemical evolution on the earth,' he added. dr gest and his assistant, jeffrey l. favinger, were about to throw out the contents of a flask—from an undergraduate's classroom experiment on photosyn- thetic bacteria that had failed because of an error in preparation—when they noticed something growing near the bottom of the flask. they isolated the organism, which had been present in soil dug up by the student in front of the biology building, and realized they had discovered 'something different'. they named the new organism heliobacterium chlorum, which translates from the greek as something like 'sun green bacterium'. all green plants must have nitrogen in order to grow. though there is plenty of nitrogen gas in the air, most plants are unable to use it and must obtain combined nitrogen from other sources, such as nitrogen-rich compounds in the soil. this is the principal reason why most crop plants need to be fertilized. but because virtually all photosynthetic bacteria are also able to take nitrogen gas from the air and use it for growth, these bacteria are prominent among biological systems that are being investigated by scientists suported by the nsf as part of a fundamental effort to determine how green plants might make their own fertilizer by taking nitrogen from the air. gest & favinger found that heliobacterium has some odd characteristics. 'this bacterium is extraordinarily sensitive to gaseous oxygen. even minute traces of oxygen completely inhibit its growth,' dr gest said. 'in addition, the bacterium contains a unique form of chlorophyll, the green light-capturing pigment. a chlorophyll molecule essentially consists of four rings of atoms that are fused together, with a magnesium atom at the centre of the structure. one of the rings has a side-branch of two linked carbon atoms. in all other known photosynthetic bacteria, this side-branch also contains one oxygen atom. but there is no oxygen atom in the side-branch of the chlorophyll in the bacterium we discovered.' 'this absence of oxygen, together with the fact that even minute traces of oxygen prevent growth of this bacterium, reinforces the idea that the bacterium evolved long before there was any oxygen gas in the earth's atmosphere—in other words, long before photosynthesis by green plants was "invented",' dr gest explained. the research workers are sending batches of the bacterium to scientists at other institutions who specialize in different areas of biochemistry and molecular biology. 'this will speed up solution of the life-style mysteries of this fascinating organism, whose ancestors were at an important crossroad in evolutionary history,' dr gest said. ralph kazarian national science foundation g street, washington dc , usa. gasifiers—a born-; there is no irony in the technological lead of the philippines and brazil in developing gasifiers; for during world war ii, when europe's oil-starved economies were under military siege, 'gasification' powered more than one million vehicles. london buses could be seen towing stove-like gasifiers on trailers, while many big cars of the s sprouted devices resembling boilers on their rear ends, and sported roof-racks full of charcoal. post-war supplies of cheap oil quickly killed gasifi- cation. after all, the gas is poisonous (mostly carbon monoxide), so dirty that engines need 'constant' cleaning, and not as 'hot' as gasoline—making gasified engines sluggish. then, in the s, rapidly-rising oil prices and falling commodity prices placed oil-importing third world countries under economic, rather than military, siege. the capital cost of a gasifier system is about one us cent higher per kilowatt/hour then that of a diesel engine, again technology and maintenance and running costs are about three cents more. but fuel for the gasified diesel costs ten cents less per kwh. the total cost of power with gasification is about % less than with straight diesel. successes in the philippines and brazil have spurred aid agencies to take a hard look at gasifiers as a means of solving the energy crisis in developing countries. wood gas cannot help all third world countries: in particular, regions without trees—such as sahelian africa or the middle east—lack the fuel to run gasifiers. but many development experts are convinced that wood gas is a commodity whose time has come around again. lloyd timberlake earthscan percy street london w p odr england, uk. oil-wells blocked to prevent war damage iran has blocked all but six of its oil-wells in the offshore nowruz and ardeshir fields with cement, virtually eliminating the possibility that future iraqi missile strikes in the area could result in increased oil pollution of the gulf, according to reports reaching the world wildlife fund international. seventy-five wells in the nowruz field, and an unspecified number that includes all wells in the nearby ardeshir field, have been blocked down to the seabed, according to industry sources. all these wells will eventually have to be re- drilled to be put back into production, these sources said. the last wells were blocked in november . the world wildlife fund and other conservation groups have been alarmed at the prospect of further damage to wells that might drastically increase oil pollution of the gulf. pollution has already virtually exterminated the population of dugongs and sea snakes, and severely affected coral reefs, marine turtles, and other living things in coastal waters. wells on two platforms in the nowruz field were still burning in november after being hit by iraqi missiles in early march. at the former time there had been no recent missile strikes against oil-wells, but there have been continuing attacks on iranian shipping, the oil terminal at kharg island, and onshore pumping and storage facili- ties. offshore oil for these facilities was being produced only in the fereidoon field, which had not been attacked. meanwhile an international conference has been sched- uled in teheran to study the environmental effects in the gulf of oil pollution caused by the war. donald allan, information director world wildlife fund international avenue du mont-blanc gland, switzerland. https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core tdwt .. grid-connected distributed energy generation system planning and scheduling w.s. ho, h.y. chin, k.c. wong, z.a. muis, h. hashim* process systems engineering centre (prospect), faculty of chemical engineering, universiti teknologi malaysia, skudai, johor, malaysia tel. + ; fax: + ; email: haslenda@cheme.utm.my received march ; accepted april a b s t r a c t conservation of fossil fuel energy, energy management (peak shaving), energy economic and pollution of energy sector has been among the recent topics of discussion. this paper examines possibilities of achieving the said topics through an integrated energy system also known as distributed energy system (des) consisting of renewable energy and energy storage devices. with aim to minimise system cost while abiding to carbon footprint reduction target and pollutant emissions limit, a mixed integer linear programming model is developed for optimisation and planning of a des. universiti teknologi malaysia, in planning to become an eco-campus, is taken as a case study for this research work. the model reveals that with a target of % carbon footprint reduction and tonne of total nitrogen oxides emissions (in a year), an annual cost of , , $/y is required, achieving a reduction of . %. keywords: distributed energy system (des); energy storage (es); carbon footprint; nitrogen oxides (nox); renewable energy (re); mixed integer linear programming (milp) . introduction fossil fuels are the main element that drives our economy today. unfortunately, our dependency on the world petroleum and natural gas reserve leads to energy crisis which subsequently causes increasing price of daily groceries, fuels and especially electricity bills, affecting mostly the end users, residential, com- mercial and industrial users alike. in order to be less affected by the fluctuating price of global fossil fuels, users can consider producing power through renew- able energy (re) resources incorporated with load shifting strategy (through energy storage (es) devices) for better efficient energy utilisation and management through a distributed energy generation (deg) system [ – ]. in fact, load shifting can solely be implemented on a grid-connected energy system without local energy production, to reduce the overall cost of electricity although increases in energy consumption may be expected due to compensation of energy losses during current inversion and charging/discharging of energy in and out of es [ ]. as for local re systems, es benefits the system by balancing out and distributes energy produced by intermittent resources such as *corresponding author. presented at the fifth annual international conference on “challenges in environmental science & engineering—cese ” melbourne, australia, – september - / - � balaban desalination publications. all rights reserved. desalination and water treatment www.deswater.com doi: . / . . ( ) – january synchronous failure: the emerging causal architecture of global crisis copyright © by the author(s). published here under license by the resilience alliance. homer-dixon, t., b. walker, r. biggs, a.-s. crépin, c. folke, e. f. lambin, g. d. peterson, j. rockström, m. scheffer, w. steffen, and m. troell. . synchronous failure: the emerging causal architecture of global crisis. ecology and society ( ): . http://dx.doi. org/ . /es- - synthesis synchronous failure: the emerging causal architecture of global crisis thomas homer-dixon , brian walker , reinette biggs , , anne-sophie crépin , , carl folke , , eric f. lambin , , garry d. peterson , johan rockström , marten scheffer , will steffen , and max troell , abstract. recent global crises reveal an emerging pattern of causation that could increasingly characterize the birth and progress of future global crises. a conceptual framework identifies this pattern’s deep causes, intermediate processes, and ultimate outcomes. the framework shows how multiple stresses can interact within a single social-ecological system to cause a shift in that system’s behavior, how simultaneous shifts of this kind in several largely discrete social-ecological systems can interact to cause a far larger intersystemic crisis, and how such a larger crisis can then rapidly propagate across multiple system boundaries to the global scale. case studies of the - financial-energy and food-energy crises illustrate the framework. suggestions are offered for future research to explore further the framework’s propositions. key words: climate change; conventional oil; financial system; global crisis; grain supply; social-ecological system introduction it has recently been proposed that identifiable boundaries mark the safe limits of human alteration of planetary biophysical systems such as nitrogen and carbon cycles (rockström, et al. a, b, steffen et al. ). by this view, exceeding specific levels of key variables in these systems significantly raises the likelihood of a regime shift, which would be a sharp, nonlinear jump or “critical transition” to an alternate state (scheffer , barnosky et al. ). should such a transition occur at an earth-system level, it could affect vital social and economic systems and quickly degrade humanity’s condition. for instance, a critical transition in earth’s climate could cause a sudden drop in world food output that then produces, in the absence of an adequate response, chronic subnational violence, state failure, and broad international conflict. however, this is a grossly simplistic account of how a catastrophic social-ecological crisis of global scope might occur. in the real world, any such crisis will have an intricate causal, spatial, and temporal structure. for example, rather than a single critical transition at the planetary scale, smaller crises originating within particular systems or geographical regions might propagate across system boundaries, connect together, and then expand into a global crisis (lee and preston ). we argue that recent global crises, especially several that occurred simultaneously in - , reveal an emerging pattern or architecture of causation that will increasingly characterize the birth and progress of crises in the future. in a conceptual framework that consists of a set of linked propositions, we identify the deep causes, intermediate processes, and ultimate outcomes of this pattern, which we call “synchronous failure” (homer- dixon , kent ). scholars and commentators have recently begun to highlight how multiple, simultaneous, and interacting global stresses, such as demographic pressure, climate change, resource scarcities, and financial instability, are increasing global systemic risk (beddington , oecd , wef , helbing , pamlin and armstrong ). they often describe the situation that humanity faces now and in coming decades as a “perfect storm” of simultaneous crises (sample , ahmed , ehrlich and ehrlich , morgan ). although evocative, this phrase implies that the crises align solely by chance. we argue rather that their simultaneity is a manifestation of an underlying causal pattern that is becoming more prevalent, and we elaborate a conceptual framework that provisionally describes this pattern. by providing a diagnosis of the emerging landscape of global risk, we hope to deepen scientific inquiry into humanity’s future challenges. the integrated framework proposed here shows how multiple stresses can interact within a single social-ecological system to cause a shift in the system’s behavior, how simultaneous shifts of this kind in several largely discrete social-ecological systems can interact to cause a far larger intersystemic crisis, and how such a larger crisis can then rapidly propagate across multiple system boundaries to the global scale. we believe we are describing a fundamentally new situation with deep ethical as well as practical implications. crises have, of course, regularly punctuated human affairs throughout our species’ history. however, when compared with the emerging pattern of crisis we discuss here, past crises, we argue, were generally less global in scope. those that became truly global, such as the great depression and world war ii, were rare and thus notable partly because of their global character. perhaps more importantly, past crises appear to have been generally less intersystemic in their causes and consequences (biggs et al. ). because past crises were less globally extensive and intersystemic, substantial resources external to the affected societies remained available for repair of these societies.[ ] partly as a result, affected societies could learn, innovate, and then perhaps fundamentally transform themselves and their institutions in the process of balsillie school of international affairs, university of waterloo, canada, csiro land and water, australia, stockholm resilience centre, stockholm university, sweden, centre for studies in complexity, stellenbosch university, south africa, beijer institute of ecological economics, royal swedish academy of sciences, sweden, earth and life institute, university of louvain, belgium, school of earth, energy & environmental sciences and woods institute for the environment, stanford university, united states, environmental sciences, aquatic ecology and water quality management, wageningen agricultural university, netherlands, fenner school of environment and society, australian national university, australia ecology and society ( ): http://www.ecologyandsociety.org/vol /iss /art / rebuilding anew, though sometimes learning was limited and crisis eventually returned. now, we argue, in an era of global change often called the anthropocene (crutzen and stoermer , crutzen , steffen et al. ), such second chances are becoming rarer. the global economy has expanded nearly -fold since the s, as measured by total global gdp, and inputs of resources from natural systems and outputs of waste back into those systems have increased about -fold (krausmann et al. ; j. b. delong, unpublished manuscript, http://holtz.org/library/social% science/ economics/estimating% world% gdp% by% delong/ estimating% world% gdp.htm). many of these natural systems, including forests, fisheries, hydrological cycles, and atmospheric and terrestrial sinks are consequently under enormous strain, and some, such as earth’s climate, are exhibiting a higher frequency of extreme behavior (hansen et al. , ipcc ). during the same period, the revolution in information technologies, the quintupling of global trade, and the homogenization of human institutions, culture, and technologies have produced a sharp increase in the connectivity and the speed of operation of human social and economic systems (chase- dunn et al. , young et al. ). the combined result of these changes has been the emergence for the first time in human history of a single, tightly coupled human social-ecological system of planetary scope. tight coupling means a major crisis is more likely to implicate most if not all of this system, so affected societies will be less likely to have access to largely unaffected societies and regions from which they can draw resources, capital, and knowledge for repair and rebuilding. in a world where external reserves of resources are limited and second chances are thus increasingly rare, humankind must develop the ability to proactively navigate away from this new kind of crisis—globally extensive and intersystemic—that could otherwise irreversibly degrade the biophysical and economic basis for human prosperity. unfortunately, humanity’s existing global institutions are ill-equipped to provide for such navigation (walker et al. ). we conclude, therefore, with recommendations for further research on both emerging patterns of global crisis and on pathways for rapid institutional evolution that could substantially reduce the risk of synchronous failure. conceptual framework in this section, we provide definitions of the core concepts and identify the main components of a conceptual framework that describes synchronous failure. a complex systems ontology informs this framework (for a survey, see mitchell ). definitions we define a “system” as a set of causally connected entities that can be considered as a whole and has sufficiently strong homeostatic mechanisms to persist as an identifiable whole over an extended period of time. the entities making up human social- ecological systems include resources, nonhuman organisms, people (including their cognitive states), organizations, institutions, and technologies (beddoe et al. ). a social-ecological system’s “coping capacity” is its ability to remain within its current stability domain or otherwise shift noncatastrophically to an alternative stability domain in which the system’s essential features and functions are sustained. our concept of coping capacity echoes that of “resilience” (folke et al. , anderies et al. ). our use of coping capacity, however, is intended to emphasize actors’ agency, specifically, the capacity of individuals or groups to choose how, when, and where to respond to systemic stress. a “stress” is a force that, if unopposed, will move a system away from its current state. a “crisis,” in the context of this paper, is a sudden event or a closely connected series of events within or across social-ecological systems that significantly harms, in a relatively short period of time, the well-being of a large number of people. this definition of crisis is substrate-neutral, in the sense that a crisis so-defined can occur in an ecological, economic, political, or technological system, or some combination of the foregoing. the definition thus allows researchers to subsume under a single analysis types of events that are conventionally treated separately. the proposed definition stipulates three necessary conditions for crisis that, taken together, are sufficient for its occurrence: suddenness (sharp nonlinearity), impact on a large population, and significant harm to that population within a relatively short period of time. each of these conditions or properties can be operationalized. in our stipulation that a crisis must actually cause significant harm, we depart from the conventional usage in which an event that could potentially lead to significant harm is sometimes called a crisis. such usage is common in discussions of international affairs, as in the label “cuban missile crisis.” by defining crisis as a phenomenon that actually causes harm, we make its identification and measurement less dependent on assessment of people’s subjective psychological states of, for instance, fear, anxiety, and perception of threat. the definition also assumes that the harm in question is a direct result of the crisis and therefore occurs relatively rapidly. it thus does not preclude the possibility that a crisis can precipitate widely beneficial changes in psychological states, social structures, and general well-being over a longer period of time. finally, we do not stipulate that unexpectedness, or perceived low probability, is a necessary condition for crisis, as do some widely cited definitions.[ ] first, events generally understood as crises are often broadly anticipated. if israel attacks iran to destroy its nuclear facilities in , the event and its immediate consequences will be called a crisis, even though they have been anticipated for years. second, nearly all crises are anticipated by someone, even if only by chance or luck. therefore, unexpectedness is not a binary variable, that is, it is not true that sudden harmful events are either expected or unexpected. because unexpectedness is a continuous variable, stipulating it as a necessary condition would require stipulating what proportion of the population the crisis must truly surprise, a significant and unnecessary complication. researchers could use our definition to generate a list of crises across recent history, say, the last century. they could then examine the list to establish trends regarding crisis frequency, type, and severity and to determine whether new patterns of crisis are emerging. ecology and society ( ): http://www.ecologyandsociety.org/vol /iss /art / deep causes of synchronous failure we argue that compared to past crises, future crises will increasingly arise from the conjunction of three underlying, long- term, and causally linked global trends. the first is the dramatic increase in the scale of human economic activity in relation to earth’s natural resources and systems. human-induced changes in natural systems now often rival or exceed changes arising from nonhuman processes (steffen et al. ). the second trend is the rapidly rising density, capacity, and transmission speed of the connections carrying material, energy, and information among the components of human technological, economic, and social systems (helbing ). this increased connectivity reduces the isolation of these systems’ components from each other and thereby increases the functional size of the overall systems of which they are a part. the third trend is the increasing homogeneity, or declining diversity, of human cultures, institutions, practices, and technologies (boli and thomas , meyer , young et al. ), including technologies that exploit ecosystem services, such as agriculture and aquaculture. although market competition in the global economy can promote diversity, positive network externalities, winner-take-all dynamics, and efforts by firms to achieve efficiencies and economies of scale across enormous markets encourage process homogeneity and a concomitant pruning of redundancy and system slack (levitt , arthur , frank and cook ). the second and third of these trends are reciprocally related, that is, they are both causes and consequences of each other, although not exclusively so. greater connectivity facilitates homogenization, while homogenization encourages greater connectivity. the three global trends contribute both separately and in combination to conditions favoring synchronous failure in three major ways. first, they generate multiple simultaneous stresses affecting human societies. these stresses build their force slowly yet are potentially very powerful over time. for instance, the first of the three above trends, the sharply rising scale of human economic activity in relation to natural resources and systems, is causing greater scarcity of some critical resources such as conventional oil (sorrell et al. , iea , höök et al. ), where this scarcity is gauged by the amount of energy needed to extract and process an additional increment of final output (davidson et al. ). it is also contributing to higher atmospheric concentrations of greenhouse gases, which are boosting the incidence of extreme climate events such as heat waves (hansen et al. , ipcc ). additionally, it is producing severe disruption of many natural systems that are vital to human well-being, including the majority of earth’s fisheries and large tracts of its grasslands and forests. for some of these systems, such as coral reefs, disruption is approaching or even exceeding the systems’ homeostatic capacity to maintain their integrity and identity (bellwood et al. , hughes et al. ). combinations of the three global trends can also produce stress. for example, climate change and the rising energetic cost of oil, both a result of the first trend, are encouraging a transition from energetically dense carbon-based fuels to alternative energy sources that are, on average, energetically costlier and less dense (heinberg ). however, enabling and sustaining the second trend, the rising connectivity and in turn complexity of human societies, requires ever-larger inputs of high-quality energy (odum , tainter et al. ). the fundamental contradiction between the two trends could cause enormous economic and social disruption this century (morgan ). second, the three global trends contribute to conditions favoring synchronous failure by increasing the risk of large and abrupt systemic disruption and by helping such disruptions propagate farther and faster through global networks. for instance, the increasing density, capacity, and transmission speed of connections among system components creates tight coupling among these components, which raises the risk of surprising and harmful interactions among them (perrow ) and of localized failures spreading quickly to other, distant system components (buldyrev et al. , harmon et al. , bashan et al. , helbing ). research on ecological and other complex networks suggests that the combination of rising connectivity and homogeneity makes a system less adaptive and, ultimately, more vulnerable to a critical transition, that is, to a wholesale systemic shift or crash (bodin and norberg , scheffer et al. , lever et al ). however, the same features can also produce benefits. for instance, greater connectivity can aid repair of local failures by facilitating the flow of inputs from nearby components (biggs et al. , scheffer et al. ). also, the combination of greater connectivity and homogeneity in human social systems could set the stage for beneficial critical transitions, such as a planetary shift toward more environmentally sustainable values, institutions, and economic practices. the above development, an increased propensity to large disruptions that propagate farther and faster through global networks, may be evidence of a more generalized trend of direct relevance to our argument here: greater synchronization in global systems. complex systems often exhibit synchronization (strogatz ). this is an “emergent” phenomenon, that is, a novel property of a whole system that arises from the interactions of its component parts. although the underlying causes of synchronization are still not fully understood, it appears likely to arise when a dense network of links among largely homogenous system components carries signals that create positive feedbacks among these components. the three global trends identified above cause today’s global systems to increasingly manifest exactly the features of dense connectivity, long-distance teleconnections, and component homogeneity that seem to encourage synchronization (biggs et al. ). we will highlight the apparent role of the global energy system in synchronizing societal crisis. finally, the three global trends can contribute to conditions favoring synchronous failure by reducing the coping capacity of societies. greater connectivity within and among technological systems and their associated social systems often makes these systems’ internal structures and mechanisms more opaque to system managers, boosts the cognitive and decision-making load borne by those managers (barrett et al. , himss ), and generally makes system prediction and control harder. opaqueness, managerial overload, and low control are increasingly apparent in systems as diverse as electrical grids and the global financial and supply-chain networks (korowicz , lee and preston , tollefson ). processes of synchronous failure the deep causes we identify above manifest themselves in three crisis processes that, together, are core characteristics of ecology and society ( ): http://www.ecologyandsociety.org/vol /iss /art / synchronous failure. each of these processes usually operates in conjunction with at least one of the other two; that is, each is rarely seen in isolation. however, each is archetypal and as such, we believe, deserves a distinct label. long fuse big bang the first process, which we call “long fuse big bang” (or lfbb), arises from the slow accumulation of a stress or stresses in a social- ecological system (the burning of the long fuse) that ultimately produces a rapid and sharply nonlinear shift in the system’s behavior (the big bang), perhaps to a new system configuration. the shift occurs when the level of stress exceeds the system’s coping capacity. in other words, it occurs when the ratio of stress to the system’s coping capacity exceeds one, assuming that valid, reliable, and independent instruments to measure both stress and coping capacity are available. we call this situation “overload.” our conceptualization of the lfbb archetype derives from two distinct yet complementary sources: political science theory on societal crisis and complex systems theory on nonlinear change. political scientists karl deutsch ( ), samuel huntington ( ), and alexander motyl ( ), among others, have proposed overload-breakdown theories of social and political crisis. huntington, for instance, argues that societies are vulnerable to instability when their level of political participation exceeds their level of political institutionalization. such theories, in turn, trace their origin to at least three distinct lines of previous thought (homer-dixon ): the functionalist sociology of Émile durkheim ( ) and talcott parsons ( ), the systems theory and cybernetics pioneered by ludwig von bertalanffy ( ) and norbert wiener ( ), and the information- processing and computational theories of cognitive scientists and organizational theorists such as herbert simon ( ). the other source of our conceptualization of lfbb, complex systems theory, proposes that sharp nonlinear shifts in system behaviour can arise in two distinct ways. in the first, change in the values of one or more state variables causes the system to jump suddenly from one place to another in a multidimensional state space; this system “flip” or critical transition can be modeled as a bifurcation on a catastrophe manifold (scheffer ). in the second type, potential energy that has slowly accumulated within the system is released in an “avalanche” event. in systems that exhibit self-organized criticality, a power law describes the frequency distribution of avalanche size (bak ). very large events, that is, avalanches in the tail of the distribution, are possible. simultaneous stresses the second process of synchronous failure, which we call the “simultaneous stresses” (ss), arises when two or more stresses combine within a single social-ecological system. correctly describing the relationship among these multiple stresses is important, and here two key questions arise. first, are the stresses causally linked or causally independent? second, do the stresses, in their combined effect, have a multiplicative or additive relationship? in regard to the first question, stresses developing within the tightly coupled social-ecological systems that increasingly characterize today’s world will rarely if ever be fully causally independent of each other. however, the causal relations between them can take a variety of forms, from linear unidirectional causation at one extreme to highly nonlinear reciprocal (or feedback) causation at the other extreme. also, causal links between stresses can occur along the full range of temporal stages in the stresses’ development. any adequate account of multiple stresses must provide detail on such complexities. in regard to the second question, a multiplicative relationship among stresses implies that their combined effect, i.e., total stress, is not a straight-forward sum of their individual contributions to that effect; the relationship among the stresses is therefore synergistic. also, a multiplicative relationship among stresses implies a logical “and” relationship among them, which means each stress is posited as necessary for the result to occur. in other words, overload can happen only when stresses x and y occur together in sufficient combined strength to exceed the system’s coping capacity. the outbreak of a vector-borne disease in a population, for example, requires both a pathogen and a vector. each is necessary for the outbreak to occur, so neither can cause the outbreak by itself. an additive relationship, on the other hand, implies a logical “or” relationship, which means any one of the identified stresses by itself could be sufficient for the outcome. in this case, overload happens when x and/or y occurs in sufficient strength to exceed the system’ coping capacity (mahoney , mahoney et al. ).[ ] the actual relationship between stresses in a given situation must be determined through empirical investigation. it is quite possible, indeed, that the best representation will involve a combination of the two types of relationships. for instance, overload may be found to happen when (x or y) and z occur together. also, researchers may determine that the overload outcome is “equifinal,” which means it could arise along multiple discrete causal pathways. in this case, researchers should ideally stipulate each pathway’s sufficient set of causes.[ ] the product of the exercise will resemble the kind of fault-tree model common in risk analysis (lee et al. ). ramifying cascade the third process archetype, which we call the “ramifying cascade „ (rc), arises when a sudden and severe perturbation of one node in a tightly coupled network propagates through the network’s links to adjacent nodes, thereby producing knock-on effects at some distance from the original perturbation. we argued above that steadily greater connectivity within human technological, economic, and social networks and between these human networks and natural systems has increased the frequency and severity of unexpected system interactions and of long-range cascading system failures (adger et al. , galaz et al. , korowicz ). each of our process archetypes highlights a distinct and critical property of the emerging pattern of social-ecological crises we call synchronous failure. the lfbb archetype emphasizes how a stress on a system can cause a sudden nonlinearity, in which the rate of system change shifts abruptly from slow to fast. the ss archetype highlights how multiple stresses operating simultaneously can combine in their total impact, often synergistically. finally, the rc archetype highlights how disruptions or shocks arising from sudden nonlinearities can propagate rapidly through modern tightly coupled social- ecological networks. ecology and society ( ): http://www.ecologyandsociety.org/vol /iss /art / fig. . synchronous failure: a conceptual framework showing the emerging causal architecture of global crisis. ss = simultaneous stresses; lfbb = long fuse big bang; rc = ramifying cascade. outcomes of synchronous failure we argue that the above causes and processes are increasingly producing crises with a distinct character compared to past crises. specifically, synchronous failure, as we call this emerging type of crisis, is more biophysical in origin, more intersystemic in manifestation, more global in scope, and more rapid in development. together, these four properties increase the risk that future crises will involve irreversible system flips on human timescales that have enormous repercussions for humankind. in figure , we bring together the various elements of our conceptual framework. the figure distinguishes between two temporal stages. in stage , which integrates the ss and lfbb process archetypes, slow processes operate within largely discrete systems. multiple slowly developing stresses combine to cause overload in these systems. with the "x" symbols between the converging arrows, we specify that the relationships between the stresses in each system are multiplicative; as discussed above, however, these relationships could also be additive. the operation of proximate triggers marks the transition between stage and stage ; these triggers cause the overload in each system to generate discrete systemic crises. the simultaneity or near- simultaneity of these crises, that is, the synchronization of their crisis behavior, arises from the systems’ causal interaction across their intersystemic boundary. in stage , which integrates the ss and rc archetypes, fast processes operate across multiple systems. here the simultaneous but previously largely discrete systemic crises combine, again synergistically, to produce a single multisystemic crisis that cascades outward through a tightly coupled global network. the ss process archetype appears in both stages. in the stage , it is slow-acting stresses that are multiple; whereas in stage , it is fast-acting crises that are multiple. the rc archetype by definition involves fast processes, whereas lfbb involves both slow and fast processes—at first slow and then fast. our framework implies that the transition between slow and fast system behavior that produces a crisis requires something like a lfbb process. the specific causal mechanisms that produce this nonlinear response will differ from system to system. some might object that the conceptual framework offered here is both too deterministic and too pessimistic. in the past, these critics might argue, multiple stresses and even crises have often spurred innovation, reorganization, and adaptation rather than catastrophic system failure. now humanity’s situation offers even more reason for optimism: scientific and technological progress has combined with the globalization of ideas and communication systems to greatly boost humankind’s ability to anticipate, understand, avoid, and respond constructively to crises. our framework thus underestimates human societies’ longer term coping or adaptive capacity. short-term overload and crisis will lead in time to creativity and adaptation that leave societies better off than they were before (wilkinson , simon ). we acknowledge this objection but argue in response that humanity’s predicament this century is largely novel and is best characterized as a race between the rapidly increasing severity and complexity of its problems and its improving but nonetheless ecology and society ( ): http://www.ecologyandsociety.org/vol /iss /art / fig. . the financial-energy crisis. ss = simultaneous stresses; lfbb = long fuse big bang; rc = ramifying cascade; eroi = energy return on investment. uncertain ability to anticipate, proactively solve, and constructively respond to these problems (homer-dixon ). in , we cannot be sure of this race’s outcome. undoubtedly, crisis can create opportunities for innovation. however, human history offers abundant evidence that these opportunities are often not exploited or that, if they are, the resulting innovation is either insufficient or of the wrong kind to produce a long-term sustainable outcome (homer-dixon ). also, many of the most severe problems that humankind now faces, such as climate change, biodiversity loss, and nutrient pollution involve the provision of global public goods (kaul et al. , barrett ). because property rights for these goods are nonexistent, unclear, or shared, the market institutions that have become the primary mechanisms of human innovation often cannot generate an adequate response (cornes and sandler ). humanity will respond more effectively to its evolving challenges if it better understands these challenges. we propose our conceptual framework with this goal in mind. it consists of a series of interlinked propositions about the emerging properties of global crisis that, we believe, deserve extended close examination. illustrations illustration : the financial-energy crisis all of our framework’s components are visible in the crisis that erupted in financial markets and the global economy in . most people recall that ongoing troubles in the u.s. subprime housing market metastasized into a global financial crisis, precipitated, especially, by the late-september collapse of the investment bank lehman brothers. however, another event of global scope occurred that year too: a rapid run-up and then collapse in oil prices. the price of light crude oil rose from us$ to nearly $ dollars a barrel between january and june and then plummeted to less than $ by the end of the year. although it may seem that the financial crisis and the energy-price shock were causally independent phenomena, we argue the two events were connected in their deep causes, proximate triggers, and intertwined consequences, as illustrated in figure . we therefore label the event a “financial-energy” crisis. it exhibited all four properties that we believe will increasingly distinguish future crises: it was global in scope; it developed extraordinarily rapidly; it was clearly intersystemic, because it emerged from the interaction of humanity’s financial and energy systems; and it was profoundly biophysical, because it was rooted, in significant part, in humanity’s use of natural resources. the global energy system is represented at the bottom of the figure. between the mid- s and , several slowly building stresses combined synergistically within that part of the system involving liquid transportation fuels. global demand for liquid fuels increased one to two percent a year, driven especially by the giant economies of china and india as they continued energy- intensive development and expanded their transportation fleets. at the same time, a rising proportion of the planet’s conventional oil production came from fields that had passed peak output and were exhibiting year-over-year production declines (sorrell et al. , iea , höök et al. ). finally, the energetic cost of ecology and society ( ): http://www.ecologyandsociety.org/vol /iss /art / finding and producing new sources of oil continued to rise steadily, which meant that the energy return on investment (eroi) fell for both conventional and nonconventional sources (guilford et al. , fournier et al. , murphy , hall et al. ).[ ] these stresses combined to sharply reduce slack in the global oil market, making it more tightly coupled and reducing the elasticity of supply for liquids (murray and king ). the global financial system is represented on the top of the figure. in united states in the s, economic policy makers broke with the prevailing keynesian orthodoxy and adopted monetarism, largely in response to the country’s experience with stagflation during the previous decade. federal reserve chairman paul volcker used sharply contractionist interest-rate policies to bring inflation under control. once inflation subsided, economic policy makers around the world responded to chronically insufficient demand, and the labor and capital unemployment it produced, by encouraging growth in the supply of credit in the economies under their direction. an antiregulation economic ideology, which complemented the monetarist shift, took hold in key policy circles, especially in the united states. the result was a two-decades-long torrent of liquidity into the global economy that produced rapid economic growth, especially in asia (reinhart ). however, the flood of liquidity also helped produce a succession of speculative bubbles, in east asia in the s, in the american information technology sector in the late s and early s, in the housing sectors in the u.s. and some parts of europe in the late s (justiniano et al. ), and in natural resource markets in the late s. in this context, a number of economic stresses combined synergistically during the decade prior to . easy credit and deregulation encouraged the practice of securitizing debt and risk, which spread across all sectors of advanced economies and widened the gap between creditors and the underlying assets securing their credit. this widening gap, in turn, eroded the ability of, and the incentive for, creditors and investors to judge asset risk accurately. meanwhile, equity traders used increasingly sophisticated computational and mathematical technologies to generate securitized assets and estimate their risk, along with faster communication technologies to trade these assets globally. the rising complexity of these assets and the increased density and speed of global interconnections between investors, investments, and markets made the behavior of the overall economic system progressively more opaque. finally, changes in the architecture of the global financial network tightened its coupling and reduced modularity, increased the concentration of assets and network connections in a small number of immense financial institutions, and depressed the diversity of liabilities and assets on banks’ balance sheets (haldane and may , forbes ). as a result of these trends in combination, policymakers, regulators, economic commentators, and investors increasingly underestimated systemic risk, that is, risk at the level of the global economy as a whole. the prevailing antiregulation ideology gave key rating agencies such as standard & poor’s and moody’s latitude to assign triple-a ratings to what were in reality extremely low-quality assets. the left side of figure represents the ss and lfbb properties of both the energy and financial systems. these systems were distinct, but they were not fully isolated from each other. indeed, even before the stresses identified above were severe inside both systems, links of two kinds had developed across their shared boundary. first, there were causal connections from the economic system to the energy system. the liquidity-driven economic growth from the late s to the mid- s led directly to surging energy and especially oil consumption. by , speculators with access to cheap credit and advanced trading technologies were multiplying the impact of the underlying absence of slack in the global oil market (juvenal and petrella ). second, there were connections in the reverse direction-from the energy system to the economic system. from the to the early s, the energy available in oil was inexpensive by historical standards. it was cheaper, in real terms, than during the entire period from to . inexpensive energy along with technical advances such as containerization meant inexpensive transportation, and inexpensive transportation encouraged the development of globe-spanning networks of producers and suppliers. the result was a rapid increase in the material connectivity of the global economy that paralleled the soaring information connectivity arising from new information technologies (chase-dunn et al. ). these bidirectional interactions, we propose, helped synchronize the behavior of global economic and energy systems, so that by mid- both simultaneously reached critical junctures and exhibited extreme susceptibility to crisis. within each system, accumulating stresses had overloaded normal coping mechanisms, in particular the usual regulating and stabilizing effects of markets. for instance, in the financial system, u.s. banks could not write off fast enough the rapid accumulation of nonperforming securitized debt tied to subprime mortgages. simultaneously, in the global energy system in the first half of , rising oil prices encouraged heavy speculation in oil futures, driving prices even higher. this was a positive or self-reinforcing feedback. normally, price signals in oil markets stimulate negative-feedback behavior: higher prices bring to market greater oil supply just as they reduce demand by encouraging conservation; both outcomes, in turn, lower prices. researchers have not reached a consensus as to the proximate trigger of the ensuing global crisis. however, the second stage of this episode of synchronous failure may have begun in the vast suburban and exurban tracts of housing in california, nevada, arizona, and florida that were the prime sites of the mid- s u.s. real-estate bubble. development of these tracts made commercial sense only when gasoline was cheap: many residents had precarious finances at the best of times and nearly all had long commutes to work, often two hours or more. as the u.s. price of gasoline passed the psychologically critical threshold of $ a gallon, as it did in early june of , a sharply higher fraction of residents and of potential buyers found houses in these zones unaffordable. defaults on mortgages on the houses soared, which meant that the value of securities backed by the mortgages plummeted.[ ] the months of june through september of thus saw the energy and financial crises, until then largely discrete, combine to spark a global, multisystemic crisis. markets did not expect ecology and society ( ): http://www.ecologyandsociety.org/vol /iss /art / fig. . the food-energy crisis. ss = simultaneous stresses; lfbb = long fuse big bang; rc = ramifying cascade. lehman brothers’ late-september collapse, and they interpreted the event as indicating the u.s. federal reserve could not manage the rising tide of defaults (swedberg ). securitized assets on the balance sheets of banks and corporations around the world suddenly had unknown value. the interdependence of bank, hedge fund, and corporate balance sheets tightened the coupling of global financial markets, so uncertainty propagated rapidly through global markets. banks and firms, not confident of the financial viability of counterparties whose balance sheets they could no longer evaluate, simply stopped doing business with each other. global trade collapsed (levchenko et al. ), and every major economic region in the world began to contract simultaneously. falling demand drove oil prices down nearly one hundred dollars a barrel in three months. only history’s largest coordinated central-bank intervention, involving the injection of trillions of dollars of additional liquidity and outright nationalization of hundreds of failing banks and industries, halted the crisis in late and early . however, many of the underlying stresses that led to the crisis, including the rising energetic costs of transportation fuel and the generally weakly regulation of financial markets, continue to operate today. illustration : the food-energy crisis between and mid- , the average global price of food nearly doubled, and in the first half of the price of grain in particular shot upwards. because poor people usually spend a large portion of household income on food, these sharply higher prices hurt tens of millions of people around the world, causing a temporary surge in malnutrition in poor countries and widespread decline in well-being, particularly in urban zones and among children (ivanic and martin , tiwari and zaman ). researchers generally explain this event as the combined result of various weather-related shocks to agricultural trade, the promotion of biofuels by rich countries, and the surge in the cost of energy inputs to agriculture due to higher oil prices (headey and fan , headey et al. , lagi et al. , wright ). export bans by a number of key food-producing countries then amplified the spike. this research rightly emphasizes that many factors interacted to cause the price surge and that the global energy system played a central role. however, for the most part it does not distinguish between long-term stresses and more temporally proximate causes. nor, generally, does it explain the mechanisms underlying the food system’s sharply nonlinear response. finally, it insufficiently highlights the crisis’s deeply intersystemic character. we capture these properties in figure , which represents the food crisis in terms of our framework. the crisis and more recent high-amplitude swings in food prices suggest that humanity’s food system is under extreme pressure and may experience much larger crises in the future (berry et al. ). ecology and society ( ): http://www.ecologyandsociety.org/vol /iss /art / over thousands of years, humankind extensively transformed earth’s biosphere as agriculture gradually expanded and diversified. in the past century, agriculture’s pace of change became much more rapid and its biospheric impacts even more pronounced. traditional, diverse agricultural systems of shifting cultivation that recycled nutrients through fallow practices or agroforestry gave way to ecologically far simpler systems relying heavily on fossil fuels for mechanized labor, irrigation, and inputs of fertilizer and pesticide. these new systems originated in europe and then spread to the americas, asia, and finally parts of africa. they produce cheap food that has enormously improved human well-being. nonetheless, because of poverty, about billion people remain malnourished today. in recent decades, four simultaneous and sometimes synergistically interacting stresses have been building within this global food system. the first is steadily diminishing availability of new, high-quality agricultural land. agriculture uses about % of the world’s land. further expansion is possible, but only a few countries, such as angola, brazil, congo, mozambique, russia, zambia, and tanzania, have enough unused land of sufficient quality to sustain any substantial increase. there is substantially less potential additional cropland than is generally assumed once ecological and socioeconomic constraints and trade-offs are taken into account (lambin et al. ). the second stress is steadily declining marginal returns to agricultural intensification in many parts of the world, that is, to incremental additions of inputs such as fertilizer, machinery, and irrigation water (fuglie ). in rich countries, intensification’s marginal benefits are already low: it can boost agricultural yields, but sustaining past rates of output growth through intensification alone usually produces external costs, such as greater water pollution and loss of ecosystem services, and these costs can significantly offset any benefits (matson and vitousek , bennett et al. , rist et al. ). in poorer regions where big gains from intensification are more achievable, social, infrastructure, and institutional problems often hinder such a strategy. in the absence of greater investment in inputs themselves —use of more fertilizer and tractors of the same type, for instance —better technologies can raise input productivity. a kilogram of fertilizer will produce much more food if technology can tell farmers which parts of their land need it most. indeed, in the last decade, higher input productivity accounted for three-quarters of growth in the world’s food output (fuglie , fuglie et al. ), but productivity improvements appear to be slackening for some cereals, especially wheat and rice (ray et al. , grassini et al. ). third, climate change has begun to affect food output by increasing, in particular, the frequency and severity of extreme weather events such as drought (lobell and field ); this impact is expected to become much more pronounced in coming decades, requiring ever-larger investments in new agricultural technologies and infrastructure (battisti and naylor , ackerman and stanton , dai ). these first three stresses operate, essentially, on the supply side of the global food system. although they have not halted output growth (fuglie et al. ), they have constrained this growth and in some cases offset its economic and social benefits. meanwhile, world food demand is rising relentlessly, constituting a fourth stress. demand is rising partly because the human population is still growing by about million people a year and partly because this population’s steadily higher average income has increased meat consumption. greater meat consumption, in turn, drives overall food consumption up the trophic hierarchy, requiring greater total food production (bonhommeau et al. ). higher demand for food generates opportunity for profit from investment in agriculture, but the three supply-side stresses described above can decrease the attractiveness of such investment. low investment further constrains future growth in global food output and raises the potential for even larger food-price spikes in coming decades. the upper left half of figure represents the global food system, showing the four above-described simultaneous stresses. together, the stresses exhibited ss and lfbb dynamics. in the years prior to - , several of them, specifically, diminished land availability, declining marginal returns to intensification, and rising food demand, started to overload the global food system’s coping capacity, including its market mechanisms and the international institutions tasked with responding to food shortfalls, such as the world food program (idc , wfp ). these institutions are supposed to act as stabilizing (negative) feedbacks in the global food system, but their effectiveness is doubtful because of their limited capacity and operational scope (walker et al. ). the bottom half of the diagram again portrays the global energy system with the three main stresses as described previously: increasing global demand for conventional oil, the decline of mature oil fields, and rising energetic cost of finding and producing a marginal barrel of oil. over the years prior to the crisis, connections developed in both directions across the shared boundary between the food and energy systems, once again contributing, we propose, to their synchronized crisis behavior. cheap oil in the s and s encouraged farmers to increase energy inputs to food production, through greater mechanization and irrigation and greater use of fertilizer. rising oil prices in the s then directly boosted the cost of food (headey and fan , baffes and dennis ). rising prices also encouraged farmers to use their land to grow biofuels that substitute for petroleum-derived transportation fuel.[ ] because cropland can now grow either food or feedstock for biofuel, human agricultural and energy systems are bidirectionally coupled (hertel and beckman , searchinger and heimlich ). products of the energy system are an input to the agricultural system, and products of the agricultural system are an input into the energy system. although analysts were aware of the above factors prior to the food crisis, the event nevertheless surprised most experts. few anticipated how, in the context of the four stresses on the food system described here, low carryover stocks of grain from amplified the sensitivity of the global food system to various proximate shocks, such as an extended australian drought (wright ). the world’s immediate responses made the problem worse, partly because the dynamics of the crisis were so poorly grasped. in particular, some food-producing countries, including brazil, india, and vietnam, banned exports, further driving up prices (mitra and josling ). also, many countries exhibited little short-run resilience in the face of food shortages and price ecology and society ( ): http://www.ecologyandsociety.org/vol /iss /art / increases, having previously reduced their national stores of grain on the assumption that efficient international food markets made large-scale food crises improbable. the global financial system played a role too, although it is unclear how much speculation in futures markets affected the crisis. some research shows evidence of a strong impact, whereas other research has found little (gilbert , lagi et al. , aulerich et al. ). nevertheless, it is certainly true that financial deregulation and the development of new classes of derivatives encouraged index-based investment in food markets that were previously used almost exclusively to hedge producers’ risk. the food crisis had vast multisystem impacts. we have mentioned its implications for the well-being of families, individuals, and especially children around the world. the surge in food prices also destabilized many political systems: food riots and violence broke out in dozens of poor countries, including bangladesh, burkina faso, cameroon, egypt, indonesia, and yemen. however, the global food system showed resilience over the medium term. farmers responded strongly to higher prices: food production in major wheat and maize exporting countries rose by % to % the following year, and china and india increased their public agricultural spending sharply (headey et al. ). all the same, prices generally remained higher than they had been in the s or s, and they appeared to become more volatile. these conditions set the stage for further food-system instability. in august , russian authorities banned grain exports after russian crops were damaged by severe drought and record heat, a weather phenomenon possibly attributable to climate change. within weeks, key grain prices surged upwards, and in the fourth quarter of world food prices overall shot past levels. by spring , food prices worldwide were averaging % above levels. higher food prices were likely a proximate trigger of the uprisings that began in tunisia in december and convulsed nearly countries in the middle east and north africa through the winter and spring of (johnstone and mazo , werrell and femla ). conclusion: future research in this paper, we have elaborated a conceptual framework that shows the emerging causal architecture of global crisis, which we call synchronous failure. this framework identifies the phenomenon’s deep causes, characteristic processes, and common outcomes. we illustrated our framework with accounts of two recent global crises, the financial-energy crisis and the food-energy crisis. in light of our analysis, it is striking that both of these crises occurred in and that, in both, the global energy system, in particular the global conventional-oil system, played a central role. indeed, because of the energy system’s role, both crises could be considered together as a single three-system instance of synchronous failure. as researchers consider how the form and incidence of major crisis is changing, the causal role of the global energy system deserves special attention. only enormous inputs of inexpensive high-quality energy can create and sustain the unprecedented connectivity and complexity of human civilization, including the connectivity described here among this civilization’s diverse component systems. as a provisional hypothesis, therefore, it seems reasonable to propose that the global energy system helps to synchronize these systems’ behavior and to stimulate simultaneous crises within and across them. other factors such as global trade and transport systems, the internet, and simultaneous scarcity of multiple resources (seppelt et al. ) may also play synchronizing roles, but these factors themselves depend on, and are therefore significantly derivative of, massive flows of energy. global adjustment to worsening energy scarcity is unlikely to be smooth. the rising energetic cost of energy stimulates boom-bust investment cycles and alternating episodes of glut and scarcity (jackson and smith ). in late and early , global oil supply exceeded demand by a relatively small amount, about % to % on a daily basis, yet international oil prices dropped by %. the drop has generated instabilities in the global economy, with key oil-producing economies experiencing a precipitous decline in revenues. despite the fall in prices, global oil markets still exhibit limited slack and therefore remain vulnerable to geopolitical disruption, arising from, for instance, instability in the middle east, that could be the proximate cause of larger intersystemic crisis. more generally, researchers should closely investigate the complex, dense, and evolving causal links among humanity’s energy, food, water, climate, and financial systems, along with the implications of these links for long-term human well-being. although research programs have explored the relationships between specific pairs of these systems, for instance, the water- food, energy-finance, energy-climate, and climate-food relationships, no research program has explicated the joint and coevolving behavior of all five systems together, especially not in light of the biosphere’s capacity to sustain these systems (steffen et al. , galaz et al. ). yet humanity’s fate likely resides at the nexus of these systems.[ ] our proposed framework could guide a systematic analysis of recent global crises. such an analysis would help to refine the framework. it could also identify early-warning indicators and appropriate interventions that enhance societal resilience and adaptive governance and, ultimately, reduce the danger of synchronous failure. __________ [ ] the collapse of the soviet union and its associated empire in the late s and early s is an example of such a geographically and systemically bounded crisis. [ ]for instance, seeger, sellnow, and ulmer define an organizational crisis as “a specific, unexpected, and nonroutine event or series of events that create high levels of uncertainty and threaten or are perceived to threaten an organization’s high- priority goals” (seeger et al. : ). [ ] in an additive relationship, one stress can mask the effect of another. for example, high regional concentrations of sulfate aerosols can mask the generalized warming effect of rising atmospheric concentrations of carbon dioxide. [ ] technically, this would be a representation of inus causation, in which each cause is an insufficient but necessary member of a set of causes that is itself unnecessary but sufficient for the equifinal outcome of system overload (mahoney , mahoney et al. ). ecology and society ( ): http://www.ecologyandsociety.org/vol /iss /art / [ ] the eroi trends mentioned here are well-documented (hall et al. ). new technologies like hydrofracking and steam- assisted gravity drainage (sagd) have brought large quantities of new oil online, especially from unconventional tight-oil and bitumen formations, but this supply is energetically much more expensive than conventional oil (murphy ). meanwhile, around the world mature conventional oil fields are rapidly declining at about % to % a year (iea ). fracking and sagd technologies may partially compensate for this decline, but at greatly increased energetic cost (hughes ). [ ] hamilton ( ) writes: “[there was] an interaction effect between the oil shock and the problems in housing. [in] the los angeles, tampa, pittsburgh, chicago, and portland-vancouver metropolitan statistical areas, house prices in were likely to rise slightly in the zip codes closest to the central urban areas but fall significantly in zip codes with longer average commuting distances. foreclosure rates also rose with distance from the center. and certainly to the extent that the oil shock made a direct contribution to lower income and higher unemployment, that would also depress housing demand.” [ ] in the united states, this substitution was reinforced by the renewable fuel standard, which mandates that producers of transportation fuel blend into their product a specified proportion of biofuels. [ ] the shell corporation has sponsored examination of the links between the global energy, water, and food systems. see: http:// s .static-shell.com/content/dam/shell-new/local/corporate/corporate/ downloads/pdf/powering-progress-together/ppt-rotterdam- - event-report- .pdf. responses to this article can be read online at: http://www.ecologyandsociety.org/issues/responses. php/ acknowledgments: we wish to acknowledge the substantive contributions of nick bostrom, gary bowden, lisa deutsch, jerker lokrantz, eric nævdal, toby ord, and anders sandberg. reinette biggs is supported by a swiss eth society in science fellowship, and a mistra grant to the stockholm resilience centre. this article was initiated at the inconvenient feedbacks in global dynamics workshop, organized in april in stockholm as part of the joint research program on “global dynamics and resilience,” of the beijer institute of ecological economics of the royal swedish academy of sciences and the stockholm resilience centre. economic support from the anna-greta och holger crafoords foundation and the foundation till bröderna jacob och marcus wallenbergs minne is gratefully acknowledged. many thanks to joan hewer for assisting with research and formatting and to jerker lokrantz for preparing the figures. literature cited ackerman, f., and e. stanton. . climate impacts on agriculture: a challenge to complacency. working paper - . global development and environmental institute, tufts university, somerville, massachusetts, usa. 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e-mail address: e.wishanti@ub.ac.id © the authors. published by elsevier b.v this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of sustain society http://crossmark.crossref.org/dialog/?doi= . /j.proenv. . . &domain=pdf http://crossmark.crossref.org/dialog/?doi= . /j.proenv. . . &domain=pdf dewa ayu putu eva wishanti / procedia environmental sciences ( ) – . introduction energy poverty presents as a concept of the lack of access to basic energy source for simple cooking and heating in household level [ ]. many underprivileged indonesians are still using firewood and kerosene for their daily activities. according to the world bank, indonesia stands as the world's largest exporter of coal by weight, and was the eighth largest exporter of natural gas in . by contrast, the country also has approximately million people who rely on wood and biomass cook stoves. indonesia is in a great dependence to fossil-fuel to establish and run its national economic activities. the export of raw oil, coal, and other minerals are the nation's major revenue. indonesia projects itself to become a more industrialized country, meanwhile poverty and lack of renewable energy development are present as obstacles to the goal. the united nations (un) has been campaigning on sustainable energy for all which aimed at three goals: universal access to modern energy services, reducing global energy intensity by per cent, and increasing renewable energy globally to per cent of total primary energy supply. these actions urge collaboration among governments, companies, and civil society [ ]. by , the millennium development goals (mdgs) agenda will reach its end, with less specific targets on increasing the access to basic energy source for the people. indonesia has contributed to upbring the energy issues internationally as a policy input to post-mdgs national development agenda, which contains four more agenda to add to the previous eight; one of them is secure sustainable energy (point ) on the report of the high level panel of eminent persons on the post- development agenda. however, the indonesian blueprint of national energy governance - exposes many obstacles facing the challenge to deliver energy access for the poor. the blueprint does not particularly acknowledge to re-establish and re-manage the role of energy policy stakeholders. the blueprint also views energy sustainability on a more trade-related perspective rather a development-related perspective, which puts human development upon its concern. furthermore, as published on indonesian energy outlook , the country still struggles to distribute energy for transportation and mineral processing industries [ ]. the subsidy policy of basic energy, mainly on petroleum for daily basis utilization, has been conducted by the government of indonesia to shortly reduce political tensions and civil unrests. in the long term, petroleu m subsidy will result in a more critical state of energy poverty, when the energy use is largely allocated to consumptive activities. moreover, the energy export value is lower than the imported refined petroleum and liquid natural gas (lng), as the above blueprint states. upon political field as a ground of decision making process on national interests, energy poverty is conceptually new to indonesian government, apart from its ineffective institutions and regulations, less collaborative business frameworks, and less-organized civil society. therefore, there is an urgent need to re-frame the concept of "energy security" into "energy poverty" focused on the access to small and medium scale energy development as an integral entity to national energy planning and international energy cooperation. the expected result is to transform the underprivileged society to an energy-empowered one, providing them with more power and mobility to enhance the economy and participation in decision-making. . conceptual frameworks . . post- energy poverty paradigm the un advisory group on energy and climate change has acknowledged that there is no particular concern upon energy related to mdgs, but it is considered more significant after several calls on the need for universal access to modern energy by [ ]. the targets would be access to electricity and access to clean cooking facilities. there are several implications on fuel poverty and energy inefficiency, such as housing quality, energy prices, and income level. . . energy development in indonesia government of indonesia has imposed the presidential regulation (peraturan presiden) no. / on national energy policy (kebijakan energi nasional, ken). it aims at a target for the optimal energy mix in . the major key policies and objectives related to energy in indonesia consist of four main themes: (a) diversification; (b) dewa ayu putu eva wishanti / procedia environmental sciences ( ) – rational energy pricing; (c) energy sector reform; and (d) rural electrification. the ken favors the argument that energy pricing policy is the basic term of the concept on "access to energy", while every local and provincial problem greatly varies. on the other side, a thorough need-assessment is needed as a basis for financing to actually scale up the diversification of energy source [ ]. however, on political field, foreign intervention on national energy policy allows the government to reduce its self- determination from foreign transnational corporations (tncs) and foreign investment. in addition, energy policymaking in indonesia is largely based on populist approach, given the political context in post-reformation governance restructuration. the fossil fuel subsidy policy is the most controversial subject when it materializes to the purchasing power markdown of the lower economic class of the society, as it directly affects the poverty rate. . . methodology this article utilizes two methods of gap analysis to measure energy poverty, which are (a) the policy gap between the four kinds of policies above and the implementation during - (starting in the year of the blueprint to recently); (b) the gap and/or trends between energy use on national consumption and industrial activities during - mainly on fuel, electricity, and the rate of household access to modern energy. those two analysis will be assessed to identify the problem, and conceptualize them to reframe the perspectives upon national energy policy inputs. the data were obtained from international energy agency, the indonesian ministry of energy and mineral resources, undp human development index, unido, and other relevant indices. since poverty consists of multidimensional approaches, this article uses a pragmatic point of view in recommending the policy inputs, bringing an open-ended conclusion thereafter. . discussion and findings . . national energy development policy poverty is a concept of social convention that is relatively inconsistent in terms of policy discussions. poverty line in indonesia is often based on the basic expenditure of food consumption and households [ ], meanwhile there is so little account on basic modern energy access. on the other hand, energy sustainability on macroeconomic level is quite instable. the un sustainable energy for all initiative (se all) at the end of mdgs in allows its member countries to proceed in following several steps: (a) country opt-in; (b) stock-taking and gap analysis; (c) strengthening national action plan and program; and (d) implementation and monitoring (iesr, ). this implies that post- energy development agenda is focused on se all targets, and recently indonesia is on the phase of stock-taking and gap analysis, which makes this research is relevant to date. on this stage, the article will focus on the potential of multi-party consultation and potential partnership. the national development agency or bappenas has formulated the national long-term development plan or rencana pembangunan jangka panjang nasional (rpjp) - . the plan focuses mainly on developing renewables, increasing the oil and gas production, optimizing energy infrastructure, maximizing the outreach of electricity sector, and developing science and technology to cope with energy crisis [ ]. the four indicators of ken can be derived into four major policies, which are (a) energy mix plan to be reached by ; (b) rational energy pricing by price subsidy or fuel price rationalization, and green-technology stimulus; (c) energy sector reform and (d) rural electrification. the energy mix program, based on the framework, does not involve the civil society and local stakeholders. the directorate general of new energy, renewable energy, and energy conservation of the energy and mineral resources ministry propose seven programs of energy conservation, relying on macroeconomic approach rather than local approach, namely the incentives, fiscal, etc., and they also plan to conduct public awareness events which only can be accessed in urban areas [ ]. a state on the rise should emphasize more attention on its national stakeholders to achieve the targets, namely on development and planning, public enterprises and national treasuries. these actors should adapt to cross cut issues and local parties like civil society, private sector actors, as well as formal and informal local structures [ ]. business relations usually pay respects toward producers and consumers' interests, and they also imply in state-civilians dewa ayu putu eva wishanti / procedia environmental sciences ( ) – relations, in order to build trust and to channel feedbacks to each parties. upon achieving the goals of mdgs, it is relatively low on risk when involving civil society into education or health issues, or environment. however, it is more complicated to govern energy issues when it comes to embrace society insights on access, affordability, and quality. the energy sector reform has left many agenda to come by. rural area becomes the basis of energy development so that the underprivileged people are covered. on that account, goi established the master plan of acceleration and expansion of indonesian economic development or simply called mp ei as a breakthrough in placing kalimantan island corridor as a frontline of "energy stock", naming it as a center of mining stock production and processing, and national energy shed. nevertheless, this does not abandon the fact that urban areas are also still facing energy poverty, especially in developing world. to date, java and bali island as the most populated area in indonesia are also facing energy crisis, particularly on electricity. the state electricity company or perusahaan listrik negara (pln) states that in , electricity access will be in alarming status as the electricity reserve margin gradually declines when there is no new power plant projects which are operational due to unexplained delay. kalimantan energy megaprojects like mp ei are also vulnerable to reduce energy efficiency and flexibility, so that small scale energy projects, on solar, wind, or other renewables, will increase reliability, security, and also greater flexibility to reduce lifetime costs [ ]. indonesia has gone through energy sector reformation for several decades from the new order era until the reformation era. the country also breaks through the choices to liberalize energy sectors to create national political and social stabilization. the provision of energy and energy price can be a weakness in political maneuvers, so that the development policy also becomes the main ground for the economic technocrats. indonesia became a member on opec at the same time of oil boom and its export earnings from oil taxes, paid by foreign oil companies, grew sharply [ ]. on the other side, the liberalization have increased the energy price and underprivileged citizen has very little purchasing power. indonesia is out from opec and becomes an oil net importer. when energy subsidy in the form of cash subsidy is introduced, it is a sign that indonesia has a serious problem of energy inequity and the country answers the challenge with a rather reactive energy subsidy on fossil fuels. it can be understood to slow down the inflation rate; however, under the oil and gas law, energy sector reform based on price subsidy is proven to be ineffective in reducing poverty. widening the fossil fuel exploration and exploitation projects of oil blocks is also on the verge of political conflicts and authorities overlap among the government energy agencies, namely the skk migas, pt pertamina and ministry of energy and mineral resources. to get rid of the institutional clash of interests and to be able to perform structural change in energy management, government should not be steered by unidentified interests from certain stakeholders, unless states desire to face stagnation in development. this is usually between business communities and civil society, as rapid industrialization often negatively affects the surrounding local communities. local communities as well as ngos are a growing and active population aware of local issues. these groups of civil society cover a wide range of social, political, even environmental issues to be addressed. despite their quite limited magnitude of actions, these groups could perform micro risk and gap analysis between the pattern of local energy use and energy sustainability. macro indicators are limited in measuring access to the poor and their policy flaws toward energy affordability and quality. most of the rural areas and other area with geographical challenges face different circumstances of potential energy sources. this has to be highlighted in governance. the governance would be best performed in multi-actor collaboration, while also acknowledging the role of civil society, beside industry and policymakers. industrialization is often embedded in national economic policy in developing countries as the process contributes directly to economic growth, by assuming that growth will create more growth. the role of energy in bridging the industrial interest and poverty eradication interests is in the term of technology [ ]. energy equity would be more accelerated when government also stimulates to invest in technology. upon assessing rural electrification, government of indonesia (goi) finds it difficult to establish new power plant outside the island of java, namely in bali. there is a strong opposition by locals toward pt. indonesia power to operate the new plant in pesanggahan, which claims that it destroys the balance of the ecosystem and breaches the sacred land. after all, there are two main obstacles in rural electrification in the country, that are (a) the centralized java-bali electrification on policy and financing; and b) the less inclusive electricity policymaking at the provincial and districts level. about . % of the population did not enjoy the electrification by the end of , though the electrification trend was positive each year on increasing the average percentage of . % in - . however, dewa ayu putu eva wishanti / procedia environmental sciences ( ) – the data in show that . % of the population owned access to electricity, which could be assumed as a huge leap (referring to energy sustainability index vol. ). this apparently large gap in data delivery not only presents the methodological gap in researching, but also reflects different perspectives on measuring the electricity access rate. another possibility of data gap on rural data collection and measurements is the lack of involvement of the civil society in policymaking. . . trends and gap on small and medium scale energy access small and medium energy scale is varied in measurements by each energy sector. a benchmark is exampled by wind energy capacity output measurements, where small scale is on minimum kilowatt per installation, and the medium scale is from - megawatt per installation [ ]. the development of small and medium scale energy installation, especially on electricity, is not yet explicitly recommended by national energy policy (ken), as there is no national research on its feasibility and it lacks of need assessments. most developing world countries, like bangladesh, lebanon, and china, identify that suitable energy and methods of power-generating installations are off-grid; shifting to local potentials such as hydropower, solar and wind; and should be decentralized from the main grid. [ ] [ ] the development of solar energy includes the use of solar power plants in the rural and city areas, which support the commercialization of solar power plants by maximizing the private sector role, the development of domestic solar power plants industry, and the creation of an efficient funding system through the involvement of banking sector. human development index (hdi), as calculated by undp, expands on how the goals of mdgs are reflected and measured. in addition, post- goals also include more goals on secure sustainable energy, which could be viewed through the energy development index (edi). edi consists of four indicators that instantly and broadly explain the energy poverty status of a country, which are: (a) per capita commercial energy consumption (tonne of oil equivalent or toe); (b) per capita electricity consumption in residential sector (toe); (c) share of modern fuels in total household sectors energy use (percentage); and (d) share of population with access to electricity (percentage). the indicators combine economic development status and particularly upon medium and to ). as global poverty rate experiences change per year, the benchmarking countries also differ every year. the index is explained by the following formula: indicator = actual value - minimum value maximum value - minimum value fig. . formula of measuring energy poverty (international energy agency, ) table presents the minimum and maximal values used in the calculation of energy development index by using the data from pusatin, ministry of energy and mineral resources year . table . the minimum and maximal values used in the calculation of the energy development index indicator minimum value (country) maximum value (country) share of modern fuels in total residential sectors energy use (%) . (ethiopia) (yemen, lebanon, syria, iran) share of population with access to electricity (%) . (d.r. of congo) (jordan, lebanon) source : international energy agency, dewa ayu putu eva wishanti / procedia environmental sciences ( ) – by assuming the value is stable, the modern energy is defined by the access to lpg, gas, and electricity based on the handbook of energy and economics statistics of indonesia. the calculation of point (c) and (d) is used to measure energy poverty as follows: i. share of modern fuels in total indonesian household sectors energy use ( - data) : year percentage index . . . . . ii. share of indonesian population with access to electricity ( - data) year percentage index . . . . . . numerically, the latest trend shows that energy affordability increases every year, but the challenge of energy quality and productivity remains unassessed. comparing the index directly with hdi would create lack of interconnectedness between indices and could not explain social transformation and policy direction. energy poverty, on the other hand, has fundamental effects on political stability. the ken blueprint views energy in trade perspectives, where oil and gas are considered tradable commodities. although the article's interpretation is widely blurred, energy sector reform and subsidy policy reform are not proven to increase more productivity and competitiveness of civil society as mandated by the constitution. government is not well-informed that off-grid solutions are being discussed and practiced on the grassroot level, e.g. the dayak iban tribe in deep kalimantan forest has begun to develop solar panels with the assistance of local and international ngos. the ken blueprint also addresses energy diversification and rational energy pricing as one of the frameworks to enhance energy access. however, as mentioned above, energy problem across the nation is varied and this sub- framework tends to create high tension politically, as populist approach is still favoured by the government. by , there were million people ( %) in indonesia without access to electricity, and million people ( %) still utilize traditional biomass for cooking activities [ ]. most of people spend a large portion of their income to purchase energy, on the other side people with higher purchasing power have no access to modern energy supply. nevertheless, innovations on small and medium scale energy and electricity plants in isolated areas are ongoing [ ]. researchers have calculated the economic efficiency of renewable energy based village grids (rvg), and it is proven to be less costly in indonesian village as it also reduces diesel content. although goi has provided usd million and collected grants from international donors, private investors are fundamentally needed to add up the gap of financing energy infrastructure, especially for renewables and rural area outreach. one of the most feasible off-grid electricity accesses in indonesian villages is the micro-hydropower and solar battery which are also environmental friendly and reduce co emission by significant amount of . - . tco per year per village, compared to diesel substances. . . analysis government agencies are often missed in relating energy poverty and development plans to each other and stand independently in separate goals and targets. thus making the goals in poverty eradication in general is stalled. institutional adaptation and cooperation are urgently required among the national energy stakeholders. public and private sectors have several essential differences in assessing rural energy needs and how to socialize them on shifting traditional use of energy source to the cleaner sources. moreover, there is also weighted difference on targets of development among government agencies, whether it is social or economic. however, indicators on dewa ayu putu eva wishanti / procedia environmental sciences ( ) – energy development do not automatically reflect its sustainability [ ]. this might be the reason why countries set their own indicators and freely interpret sustainable development, thus create a gap in concept and government structure of knowledge. tackling energy poverty needs rural approach, while goi has allocated its efforts to fulfill the energy necessity in emerging urban areas. however, goi still struggles to maintain its conventional energy policy, which has major dependency on fossil fuels. on grassroots level, the people also experience hard time in converting kerosene and traditional cooking equipment to cleaner source of energy, namely gas and solar panels. on the other hand, most developing world governments simply view "access of energy", that is in principle of “have" or "have not", rather than an energy capacity to stimulate productive activities, living up communities, and ability to serve basic household necessities. overall, fossil fuels dependency still stands as a hindrance to alleviate people from poverty, furthermore, extreme poverty. the role of energy in poverty eradication should be defined from its utilization outcome, rather than a mere static circumstance of provision with any possible access without sustainability. goi needs to improve its strategic and institutional structure, when there is less single perspectives upon economic growth, which is on industrial level, in order to balance the development needs of its society. economic growth could give more tangible political and diplomatic impact on incumbent government's profile, but sacrificing the human development is not an option. foreign investment on oil since the dawn of fossil fuel price rationalization has increased, particularly on the clause to subsidize production process and to lower the retail price of goods. energy financing is also closely related to energy sector reform, particularly on electricity sectors and program of goi to achieve energy mix on . electricity and cleaner cooking facilities become the main priority to achieve a goal in mdgs to eradicate extreme poverty. the expansion of electricity grid is expected to cover % of national demand in ; however, the expansion of access and new power plant development requires large amount of fund. there are also insights on expanding off-grid energy access but they are mostly ignored by policymakers. most of energy development fund comes from foreign aid and assistance. foreign interests indirectly affect the national structure and strategies for energy development. it is safe to assume that foreign investments and aids are aimed to comply with their national interest, which creates market in developing countries. globally, most of bilateral energy development assistance among countries is mainly allocated on fixed capital access and technology transfers in developing world, with less than % of the global assistance funds from to was used to improve the local capacity and energy self-sufficiency [ ]. for comparison purposes, japan as the largest donor of official development assistance (oda) to indonesia also delivers energy assistance. japan's interest in indonesian energy sector is proven through its major allocation in energy sector on - . the oda breakdown is as follows : loan aid for energy dominates other sectors by usd , . million or . % from total usd , , million; while grant aid on energy sector is only usd . million from total usd . million [ ]. larger element of grant is paramount necessity, where national development agenda could be relatively maximized. when it relates to energy mix goals, these financing challenges can slow down the progress in achieving the target for the mix on renewables and non-renewable energy source. energy sector development is a substantial trigger to stimulate the economic growth and human development. however, this sector has more economical risk than other development sectors, which make energy development aid is essential. while indonesia gains it mostly from japan, indonesia has lack of bargaining position to add more portion to technical assistance and lack of grant aid to assist local energy development sectors which can provide more room for improvement. local energy development presents several challenges on geography, native culture, market type, and gap on level of economic development and gap of education level among provinces. mdgs also provides two types of indicators: income-generating and non-income-generating indicators. it is relatively easier to measure targets of universal education, or even more the intensity of cooperation and the increase of wage. however, the non-income indicators on quality of environment, health status of the citizens, energy and women empowerment are not the top priority for the populist government to eradicate poverty and to increase productivity. in president yudhoyono era, several economic approaches were conducted to become the bumper of poverty incline after the petroleum subsidy was lifted gradually. one of them was bantuan langsung tunai or direct cash subsidy for vulnerable families. this controversial policy did not address the decline of productivities and community services, thus brought social unrest among the poor. post- development agenda implementation should emphasize more on balancing energy sectors trapped between trade perspectives and development perspectives. development policies are meant to bring economic dewa ayu putu eva wishanti / procedia environmental sciences ( ) – transformation as well as social transformation. poverty and access to welfare should be more related on the latter without abandoning the economic sectors. economic growth may be increased per year, but the number of poor people remains unmoved in percentage. even the decline of political patronage by the provincial government to central government could not bridge the economic gap among provinces particularly in eastern parts of indonesia. . . conclusion this article is initially designed to produce policy inputs, which lead to the analysis to the outcome of integrating energy access into national development strategies and are supported by integrated financial and technological system at macro-economic level. identifying the opportunities to build small and medium-scale energy development will be the main source for formulating the policy inputs government of indonesia is urged to establish capacity building for the people in maintaining the risk of energy poverty and the potential loss from it. an integrated policy between human development and national energy policy should not be limited to the state-centered cooperation schemes, but it extends the capability and capacity of the people to access and maintain the basic daily energy necessity. . references . bazilian, morgan; et. al., partnerships for access to modern cooking fuels and technologies. environmental sustainability. ; ; - . sovacool, benjamin k; et. al., what moves and works: broadening the consideration of energy poverty. energy policy ; ; – . sugiyono, agus et. al. (eds),. indonesia energy outlook . ; indonesian agency for the assessment and application of technology . iea/oecd. world energy outlook, . blueprint of national energy governance - . government of indonesia . pradhan, meno et. al.,measurements of poverty in indonesia : , , and beyond. ; social monitoring and early response unit (smeru) working paper . bappenas, rencana pembangunan jangka panjang - . . ebtke directorate, ministry of energy and mineral resources.mencapai target energi, energi terbarukan dan konservasi energi di indonesia: tantangan/hambatan dan strategi. public dialogue. . bazilian, morgan; smitha nakhoda, thijs van de graaf. energy governance and poverty. . energy research & social science ( ) – . thaler, jeffrey. fiddling as the world floods and burns: how climate change urgently requires a paradigm shift in the permitting of renew-able energy projects. . environmental law journal ( ) . hossain, akhtar. macroeconomic developments, policies and issues in indonesia, - : a review. malaysian journal of economic studies; jun-dec ; , / ; . moe, espen. energy, industry and politics: energy, vested interests, and long-term economic growth and development. energy : . – . anwar, yunita; and martin surya mulyadi.income tax incentives on renewable energy industry: case of usa, china, and indonesia . the business review cambridge. . : . khodr, hiba and khatarina uherova hasbani. the dynamics of energy policy in lebanon when research, politics, and policy fail to intersect. . energy policy. : – . iea/oecd. world energy outlook, . blum, nicola u.; ratri sryantoro wakeling, tobias s. schmidt. rural electrification through village grids—assessing the cost competitiveness of isolated renewable energy technologies in indonesia. . renewable and sustainable energy reviews : – . international atomic energy agency. energy indicators of sustainable development:guidelines and methodologies. . martinot ,eric; chaurey akanksha, lew debra, moreira jose r,wamukonya njeri. renewable energy markets in developing countries. annual review energy environ ; : – . official development assistance from japan to indonesia. japan's official development assistance white paper - pii: s - ( ) - ��� �����	 ��� ��� �
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(�!!a) k�$, +, !�-���./���� ��) ��� �	��) ��	�	�� &� %''% $$! http://luiscabral.org/iio/ch /gas_natural/ 	the california energy crisis 	what happened? 	what went wrong? 	the wholesale market 	some possible solutions 	conclusion 	references b r u c e b u f f e t t turbulent flow in earth’s liquid­iron core generates the planet’s magnetic field through a process known as the geodynamo. this process is sustained by energy drawn from the core as it slowly cools . thermal convection is thought to be crucial, but revised estimates , of thermal conducti­ vity in liquid iron at high pressure have called into question the adequacy of the commonly cited energy sources . on page  of this issue, o’rourke and stevenson propose a solution to this energy crisis. they argue that if magnesium had dissolved in the liquid iron at high temperature when the core formed, then subsequent precipitation of magnesium­ bearing minerals on cooling would be an important source of energy. the authors’ theory warrants a serious reassessment of magnetic­field generation in other rocky (terrestrial) planets. sustaining a magnetic field is difficult for a terrestrial planet. creeping flow of the planet’s rocky shell (mantle) restricts heat loss from the underlying core. by comparison, the liquid­ iron core is an efficient thermal conductor. thermal convection in the core ceases when heat flow into the mantle falls below the core’s capacity to deliver this heat by conduction alone, so high thermal conductivity may push the threshold for thermal convection beyond reach. in this scenario, turbulent flow in the core is driven mainly by buoyancy effects due to variations in the abundance of core constitu­ ents — as the core cools, some of the iron solid­ ifies and accumulates on the solid inner core, leaving lighter elements in the liquid outer core and thus causing convection . a problem with this conventional view of the geodynamo’s energy sources emerges when we extrapolate back in time. before the inner core formed (possibly less than  billion years ago ), the only energy source was thermal con­ vection. but current estimates of iron’s ther­ mal conductivity suggest that the heat flow required to sustain such convection at that time was extremely high. even if this heat flow was feasible, an implausibly high core tempera­ ture would be needed to sustain it over geologi­ cal time. despite these difficulties, earth has somehow maintained a magnetic field for at least the past . billion years . o’rourke and stevenson address this quan­ dary by proposing a new energy source. they suggest that magnesium can enter the core to form an iron alloy, even though it is normally considered to be nearly insoluble in liquid iron. other alloying elements are more com­ monly proposed to explain why estimates of the core’s density, based on seismic data, are less than that of pure iron. but theoreti­ cal predictions and some experiments (see ref.  , for example) suggest that magnesium can dissolve in liquid iron at sufficiently high temperatures. the authors argue that, because of its insolubility in iron, magnesium would probably become supersaturated as the core cools. the subsequent precipitation of magnesium­bearing minerals would leave behind a residual liquid enriched in iron, pro­ viding a compositional buoyancy that would drive fluid flow (fig.  ). two factors determine whether magne­ sium precipitation is a substantial energy source. first, the amount of magnesium that dissolved in liquid iron during core formation must be sufficient to meet the energy demands of the geodynamo. second, the temperature dependence of magnesium’s solubility must be strong enough to promote supersaturation of magnesium with only a modest temperature decrease of the core (possibly just several hundred kelvin). otherwise, a delay in the onset of magnesium precipitation could shut off the energy source in the past or present. o’rourke and stevenson tackled the first issue using previously reported experimental data that describe the partitioning of elements between liquid iron and silicate melts, a mix­ ture that represents the composition and state of the mantle during core formation. these data allowed them to estimate the concen­ tration of magnesium, oxygen and silicon in liquid iron, as well as the abundance of sidero­ phile elements (those that have an affinity for iron: nickel, cobalt, chromium, vanadium, niobium and tantalum) in the silicate melt, for two models of core formation. they then used a computational technique (a monte carlo method) to assess the average temperature and pressure conditions of core formation in the two models, by sampling many possible outcomes. crucially, the researchers could account for the observed abundances of siderophiles in the mantle by using a model that permits a small fraction of the core to equilibrate with silicate melt at high temperatures (greater than ,  k). many of the monte carlo outcomes for this model are also compatible with seismological constraints on the abun­ dance of light elements in the core . these results include outcomes in which the liquid core contains – % magnesium by weight. in other words, enough magnesium to power the geodynamo could have been dissolved in the early liquid core without violating known constraints on the composition of the core and mantle , . however, uncertainties prevent a defini­ tive assessment of magnesium precipitation. some of the realizations sampled by the monte carlo method delay magnesium precipita­ tion into the distant future, whereas others permit precipitation much earlier; early and e a r t h s c i e n c e another energy source for the geodynamo magnesium is not usually considered to be a constituent of earth’s core, but its presence there has now been proposed to explain an ongoing enigma — the identity of the energy sources that drive our planet’s magnetic field. see letter p. core iron-rich �uid mantle buoyant particle accumulated magnesium minerals figure | possible processes at the boundary between earth’s liquid core and rocky mantle. o’rourke and stevenson propose that magnesium dissolved in liquid iron at high temperature when the core formed. subsequent precipitation of magnesium­containing minerals would produce buoyant solid particles that would rise through the liquid iron and accumulate at the top of the core. the residual liquid would be denser than the surrounding fluid because it is enriched in iron, and would therefore sink. the resulting vigorous convection would stir the core and generate earth’s magnetic field, at modest rates of core cooling. | n a t u r e | v o l | j a n u a r y news & viewsresearch © macmillan publishers limited. all rights reserved j e f f s e t t l e m a n many modern cancer drugs target mutationally activated proteins, but this treatment strategy has limitations. only a relatively small num­ ber of mutations are seen recurrently across human tumours , and drug resistance develops rapidly . targeting the epigenome — the chemically modified form of dna, and of associated histones and other proteins that facilitate the packaging of dna as chroma­ tin, all of which influence gene expression — is one of the alternative approaches being explored. along with two papers , published in nature last year, a paper on page  of this issue provides some insight into the potential of epigenome­targeting drugs called bet inhibitors, and outlines the mechanisms by which tumours might become resistant to these drugs. it has long been recognized that tumour cells have distinct epigenomic features, which can lead to the overproduction of cancer­ promoting transcription factors such as myc. transcription factors are challenging thera­ peutic targets, because they lack structures that can be readily targeted with drugs. but developments in our understanding of the epigenome­regulating factors that influence gene expression, many of which seem to be ‘druggable’, have provided a potential way to sidestep this hurdle. among these factors is the bromodomain protein family, which includes the bet subfamily (brd , , and t). bet proteins contain two bromodomains, each with small pockets. these pockets bind to histones that have been tagged with acetyl groups, enabling bet proteins to recruit the cell’s transcriptional machinery to specific sites in the genome to regulate gene expression. bet subfamily mem­ bers such as brd , which can regulate myc gene transcription, have been implicated in various tumours (particularly in cancers of the blood) and are therefore candidate targets for therapy . a few years ago, the first of several small­ molecule bet inhibitors (jq ) was discovered, and shown to effectively disrupt cancer­cell proliferation. this effect seemed to reflect inhibition of bet­mediated regulation of myc expression. early clinical trials of bet inhibi­ tors in leukaemia and lymphoma have been encouraging. investigators are now seeking other disease contexts in which these inhibitors might work, and predicting the acquired resist­ ance mechanisms that will inevitably arise. the two studies , converge on a potential mechanism of resistance to bet inhibition in acute myelogenous leukaemia (aml). in the first, rathert et al. screened mouse aml cells for chromatin­modifying factors that are required for aml­cell sur­ vival. they confirmed that aml cells need brd , and identified several other factors for which inhibition confers aml­cell resistance to jq . in aml cells that were jq ­resistant, the authors observed changes in specific epi­ genome features in dna enhancer regions, abundant precipitation is required to provide an effective solution to the geodynamo energy crisis. much of the uncertainty derives from the experimental estimates of element parti­ tioning between iron and silicate, particularly at high temperature. for example, the present work used information from a single set of experiments to derive magnesium’s solubility . more work is clearly required to address these uncertainties, but the potential contribution of magnesium precipitation to the geodynamo provides plenty of motivation to improve our current knowledge. magnesium precipitation would produce a buoyant solid that rises to the top of the core . the dense, iron­rich residual fluid would also contribute to vigorous convection, offering ample energy for the geodynamo at relatively modest cooling rates. such low cooling rates would allow warm fluid to accumulate at the top of the core, although convection due to magnesium precipitation might mix this warm fluid back to the core’s interior. further complications are suggested by experimental evidence that the core’s liquid is not saturated with oxygen and silicon, indicating that these elements might transfer into the core from the mantle. the potential for two­way transfer across the core–mantle boundary in the light of o’rourke and stevenson’s theory is likely to send earth scientists back to the drawing board. ■ bruce buffett is in the department of earth and planetary science, university of california, berkeley, berkeley, c a n c e r bet on drug resistance inhibitors of the bet bromodomain proteins are promising cancer therapeutics, but tumour cells are likely to become resistant to these drugs. anticipated mechanisms of resistance have now been described. see letter p. resistance in aml resistance in tnbc histone myc dna bet inhibitor β-catenin k k myc k k myc k k myc k k med ck brd brd brd p figure | circumventing bet inhibition. the bet protein brd can bind to acetyl groups (k) on histone proteins around which dna is packaged as chromatin. brd recruits the cell’s transcriptional machinery, upregulating expression of the cancer­promoting myc gene. treatment with bet inhibitors can prevent brd –chromatin binding, stilting myc transcription, but cancer cells rapidly develop drug resistance. rathert et al. and fong et al. report that, in acute myelogenous leukaemia (aml), drug resistance is conferred by activation of the wnt­signalling pathway, which leads to dna binding and myc activation by the protein β­catenin. by contrast, shu et al. find that resistance in triple­negative breast cancer (tnbc) arises owing to activation of the casein kinase (ck ) enzyme. ck phosphorylates (p) brd , allowing brd to bind to the transcriptional regulator protein med to activate myc. california - , usa. e-mail: bbuffett@berkeley.edu . nimmo, f. in treatise on geophysics nd edn (ed. schubert, g.) – (elsevier, ). . pozzo, m., davies, c., gubbins, d. & alfè, d. nature , – ( ). . gomi, h. & hirose, k. phys. earth planet. inter. , – ( ). . o’rourke, j. g. & stevenson, d. j. nature , – ( ). . tarduno, j. a. et al. science , – ( ). . badro, j., côté, a. s. & brodholt, j. p. proc. natl acad. sci. usa , – ( ). . wahl, s. m. & militzer, b. earth planet. sci. lett. , – ( ). . takafuji, n., hirose, k., mitome, m. & bando, y. geophys. res. lett. , l ( ). . fischer, r. a. et al. geochim. cosmochim. acta , – ( ). . buffett, b. a., garnero, e. j. & jeanloz, r. science , – ( ). j a n u a r y | v o l | n a t u r e | news & views research © macmillan publishers limited. all rights reserved 	another energy source for the geodynamo 	note 	references february , volume , number science .;.- .w> .i.' american association for the advancement of science science serves its readers as a forum for the presentation and discussion of important issues related to the advancement of science, including the presentation of minority or conflicting points of view, rather than by publishing only material on which a consensus has been reached. accord- ingly, all articles published in science-including editorials, news and comment, and book reviews -are signed and reflect the individual views of the authors and not official points of view adopted by the aaas or the institutions with which the authors al e affiliated editorial board alfred brown frank w. putnam 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( -pe- - ); scotch plains, n.j. : c. richard callis. unami lane ( - - ); chicago, ill. : jack ryan, room , n. michigan ave. ( -de- - ); bev- erly hills, calif. : winn nance, ill n. la cienega blvd. ( - - ) editorial correspondence: massa- chusetts ave., nw, washington. d.c. . phones: (area code ) central office: - ; book re- views: - ; business office: - ; circula- tion: - ; guide to scientific instruments: - ; news and comment: - ; reprints and permissions: - ; research news: - ; reviewing: - . cable: advancesci, washington. copies of "instructions for contributors" can be obtained from the editorial office. see also page xv. science, december . advertising cor- respondence: room , w. st., new york, n.y. . phone: -pe- - . out of the energy crunch by at the moment, the chief hope for an amelioration of the energy crisis lies in an easing of the oil embargo, but valves that can be opened can be closed. solemn agreements with the oil producing and exporting countries, ostensibly valid for decades, have been scrapped in weeks. the public and the economy cannot long tolerate the uncertainties of being a yo-yo in the hands of others. prior to the embargo, we were importing percent of our consump- tion. if we were to lower that to percent, consumers would pay less for hydrocarbons, foreign exchange problems would ease, and we would no longer need to obtain oil from the arabs. such a major step to energy independence could and should be taken by . the quickest path toward balancing supply and demand is conservation combined with the replacement of use of hydrocarbons by coal. thus far, the main burden of conservation has been carried by the public, which consumes directly only a minor fraction of the energy. the major potential for quick savings of hydrocarbons lies with industry. it is the largest consumer of energy; it has substantial technical resources; and, with costs soaring, it has incentives to seek economies. like the ptublic, industry generally has governed its behavior on the assumption of cheap energy. thus it has much room for improvement. all of industry has not been asleep. two good examples of organiza- tions with foresight and ingenuity are dupont and dow. both companies have emphasized conservation of energy in their plant designs and operation. during the past decade, dupont increased its volume of products percent, while energy used rose only percent. dupont has advised other large consumers about conservation through a con- sultant service. broad experience has shown that significant conservation at an industrial plant will, on the average, result in a percent reduc- tion in the plant's total energy consumption, and about half the saving can be achieved without new investment.* at dow chemical during , the company achieved a percent reduction in energy used while increasing yield. the company had as its goal a like reduction in .t another way of conserving hydrocarbons is to avoid burning them merely to produce heat. "one of the quickest and most effective ways to reduce short-falls in gas and oil is to substitute coal for them under electric utility and industrial boilers. approximately percent of the natural gas used goes to the electric and industrial sectors. some percent of the oil used goes to the same sectors. ..."t thus far, the administration has not been even-handed in its efforts to meet the energy crisis. the consumer has been the target of ex- hortations, shortages, and higher costs. industry, and especially the utilities, which usually can pass on higher prices, have been largely protected from shortages. by concentrating more attention on industry and the utilities, by in- voking some of the can-do attitudes of world war ii, by setting up a priority system to expedite procurement of scarce items, by unleashing coal as a primary energy source, and by making its use mandatory in some applications, an effective government could get us out of the energy crisis within years. it could free us from any need to use oil from undependable sources, and our example and reduced imports would contribute to loosening the worldwide grip of the oil cartel. -philip h. abelson * d. h. dawson, context , ( ). t j. c. robertson, chem. eng. , ( janu- ary ). t report of the cornell workshops on the major issues of a national energy research and development program (college of engineering, cornell university, ithaca, n.y., rev. ed., ), p. . the report of the corneul workshops provides an excellent summary of many aspects of the energy problem. it was prepared for the atomic energy commission. copies can be obtained from the u.s. atomic energy commission, technical information center, p.o. box , oak ridge, tenn. . o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ out of the energy crunch by philip h. abelson doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the is a registered trademark of aaas.scienceof science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for the advancementscience by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ editorial preface to the special issue on mesoscopic solar cells michael grätzel (✉) laboratoire de photoniques et interfaces, institut des sciences et ingénierie chimiques, École polytechnique fédérale de lausanne, lausanne, switzerland © higher education press and springer-verlag berlin heidelberg energy crisis and environment pollution are the main challenges of human beings in the th century. developing solar cells with high efficiency and stability at low production cost is an effective way to achieve “price parity” with fossil-fuel-based grid power and large-scale use of solar energy. since the breakthrough of dye-sensitized solar cells (dsscs) in , mesoscopic solar cells have been developing fast. especially in the past three years, the power conversion efficiency (pce) of perovskite solar cells based on mesoporous structure increased at an amazing rate. recently, a certificated pce of . % was reached, which is higher than the certificated record pce of polycrystalline silicon solar cells, indicating a competitive advantage. however, as new type of photovoltaics, solar cells based on dyes, quantum dots or perovskite pigments as light harvesters, still have many unknowns to be explored. i am delighted to be invited by frontiers of optoelectronics, as the guest editor of the first issue in , to arrange the special edition on mesoscopic solar cells. this issue contains review and research papers, all invited written by international well known scientists who are active in the field of mesoscopic solar cells. it covers research frontiers from dsscs, quantum-dot-sensitized solar cells to mesoscopic perovskite solar cells, from fabrication, characterization to optimization of different components of mesoscopic solar cells. this special issue offers a general view of the development of mesoscopic solar cells. one of the most important components in dsscs is the sensitizing dye. the donor-π bridge-acceptor (d-π-a) structure is the mainstream in the design of organic sensitizers. hua et al. discussed the donor design and modification strategies of metal-free sensitizers for highly-efficient dsscs, however, some sensitizers that do not follow d-π-a structure also present good efficiency when applied in dssc devices. robertson and hu summarized the atypical dyes in order to inspire more diverse designs towards highly efficient dsscs. the effect of the perovskite morphology on the photovoltaic performance is a critical factor. etgar and cohen reviewed various parameters influence and control the organo-metal halide perovskite crystallization and morphology, such as the annealing process, the precursor solvent, anti-solvent treatment and additives to the perovskite solution. except the comprehensive reviews of organic sensitizers in dssc, some research results of mesoscopic solar cells with novel photoelectrode, sensitizers, and cathode layers were presented as well. zhao et al. proposed a new architecture design, micro-scale hierarchical tio nanowires, for nanowire-based quantum-dot-sensitized solar cells to improve the photovoltaic performance. li et al. designed and synthesized a series of metal-free organic sensitizers with d-a′- π-a configurations, in which quninoxaline or benzoxadiazole moiety was incorporated into the conjugated bridge as the auxiliary electron acceptor (a′) to extend the absorption spectra and broaden the light-harvesting region. yang et al. explored the use of p ht modified carbon nanotubes (cnts@p ht) (p ht = poly( -hexylthiophene)) for the cathodes of hole transporter free, mesoscopic perovskite solar cells, simultaneously achieving high-performance, high stability and low-cost perovskite solar cells. despite of the increasing importance of ch nh pbi based organic- inorganic hybrid perovskites, studies relating to basic structural characterization of these powerful light-harvesting materials remains sparse. padture et al. conducted a systematic ambient raman spectroscopy characterization study of mapbi thin films to elucidate the possible sources of artifacts in the raman spectra, and raised the awareness of the challenges in the ambient raman spectroscopy of mapbi perovskites. i would like to thank the authors for their excellent works, which set a new landmark in this rapidly evolving and received january , e-mail: michael.graetzel@epfl.ch front. optoelectron. , ( ): – doi . /s - - - special issue: mesoscopic solar cells (guest editor: michael grätzel) fascinating field. i am particularly grateful to the strong support from prof. dexiu huang and the assistance from prof. hongwei han for this special issue. prof. michael grätzel michael grätzel, professor at the École polytechnique fédérale de lausanne, he directs there the laboratory of photonics and interfaces. he pioneered the use of mesoscopic materials in energy conversion systems, in particular photovoltaic cells, lithium ion batteries and photo-electrochemical devices for the splitting of water into hydrogen and oxygen by sunlight. he discovered a new type of solar cell based on dye sensitized nanocrystalline oxide films. mass production has started in october . author of over publications, two books and inventor of more than patents, his work has been cited over times (h-index ) making him one of the most highly cited chemists in the world. he has received prestigious awards, including the samson prime minister prize, the balzan prize, the galvani medal, the faraday medal, the harvey prize, the gerischer award, the dutch havinga award and medal, the international prize of the japanese society of coordination chemistry, the eni-italgas energy-prize and the year european grand prix of innovation. his most recent awards include the albert einstein world award of science, gutenberg research award, paul karrer gold medal and the millenium technology grand prize. he was selected by the scientific american as one of the top researchers in the world. he received a doctor's degree in natural science from the technical university berlin and honorary doctors degrees from universities (univ. liege, belgium ( ); rskilde univ., denmark ( ); huazhong univ of sci. & tech., wuhan, china ( ); nangyang tech. univ (ntu), singapore ( ); univ. lund, sweden ( ); univ. nova gorica, slovenia ( ); univ. hasselt, belgium ( ); delft univ. of technology, netherlands ( ); univ. turin (torino), italy ( ) and univ. uppsala, sweden ( )). he has been the mary upton visiting professor at cornell university and a distinguished visiting professor at the national university of singapore. he was an invited professor at the university of berkeley, the ecole nationale de chachan (paris) and delft university of technology. in , he was named distinguished honorary professor by the chinese academy of sciences (changchun) and the huazhong university of science and technology. he is a member of the swiss chemical society as well as of the european academy of science, a fellow of the royal society of chemistry and was elected honorary member of the société vaudoise des sciences naturelles and the bulgarian academy of science. front. optoelectron. , ( ): – special issue: mesoscopic solar cells (guest editor: michael grätzel) ``` pissn - eissn - progress in superconductivity and cryogenics vol. , no. , ( ), pp. ~ http://dx.doi.org/ . /psac. . . . `̀ ̀ . introduction nowadays, around the world is facing through an energy crisis that is seriously affecting the lives of people. the main reason for the energy crisis is rapidly increasing the prices of hydro-carbon resources and lack of planning to foresee the increasing energy demand in the country. fortunately, renewable energy can play an important role to minimize this crisis so most of the countries are interested to penetrate the renewable energy in their power sectors to obtain economic and environmental benefits, including appropriately chosen technology, adequate financing and payment arrangements, supportive national policies [ , ]. the global share of renewable energy in the power sector was . % of the global final energy consumption at the end of year [ ]. not let up with this trend, to cut a deep co emission, the international renewable energy agency (irena) has initiated the development of a roadmap that examines the elements necessary to achieve a double renewable share by , it means the total share of renewable energy in power generation grows from % in to nearly % in [ ]. taking account to this ambitious goal, wind energy is an essential solution because of its advantages – widespread availability around the world, diversification of rural economies by providing new types of income, no need to use fossil fuel, no costs of mining and transportation due to stable and free wind source [ ]. technically, wind energy has a short payback time and construction period [ ], high average efficiency and low environmental impacts (co emission and water consumption, land occupied) for individual energy generation technology among others renewable energy – pv, geothermal [ ]. therefore, wind energy is honored the top rank of renewable energy not only by cleanness but also by sustainability [ ]. furthermore, deployment superconducting generators technologies aim to solve reliability and high mass-problems of existing technologies. it is also a great innovation and strongly consolidates the role of wind energy development [ ]. this paper briefly review a recent status of the technology development of large scale high temperature superconducting generators (htsg) for wind power followed by an explanation of hts coated conductor challenges, cryogenics cooling system reliability, hts magnets field coil stability and others researches of technological concerns as mentioned. it will show the high potential of htsg wind turbine for contributing support the global energy demand in future. for increasing the concrete statement, the latest update of important projects by companies and research institutes which relate to the design and construction of htsg for wind turbine is also mentioned in this article. . future trend of wind energy in the real world, energy is one of the top challenges we are facing in a global society. we know that energy status of the technology development of large scale hts generators for wind turbine t. d. lea, j. h. kima, d. j. kima, c. j. boob, and h. m. kim*, a a department of electrical engineering, jeju national university, jeju, s. korea b department of electrical energy engineering, jeju international university, jeju, s. korea (received june ; revised or reviewed june ; accepted june ) abstract large wind turbine generators with high temperature superconductors (hts) are in incessant development because of their advantages such as weight and volume reduction and the increased efficiency compared with conventional technologies. in addition, nowadays the wind turbine market is growing in a function of time, increasing the capacity and energy production of the wind farms installed and increasing the electrical power for the electrical generators installed. as a consequence, it is raising the wind power energy contribution for the global electricity demand. in this study, a forecast of wind energy development will be firstly emphasized, then it continue presenting a recent status of the technology development of large scale htsg for wind power followed by an explanation of hts wire trend, cryogenics cooling systems concept, hts magnets field coil stability and other technological parts for optimization of hts generator design – operating temperature, design topology, field coil shape and level cost of energy, as well. finally, the most relevant projects and designs of hts generators specifically for offshore wind power systems are also mentioned in this study. keywords: wind energy, hts generator’s wind turbine, coated conductors, cryogenic technology * corresponding author: hmkim@jejunu.ac.kr t. d. le, j. h. kim, s. i. park, d. j. kim, c. j. boo, and h. m. kim demands are deeply tied to the other major challenges which include poverty, and health, and clean water because energy demands are only going to increase. the primary energy demand shown in fig. which is estimated by international energy agency (iea), the total required energy is mtoe (approximately x gwh) by [ ]. therefore, with the dramatic rising of this demand, energy security is no longer only about oil, and industrialized nations are no longer the only major consumers of energy. fortunately, it is estimated that the technical potential wind energy is in a huge range from x to x kwh, and the expected saturation level capacity is gw during - [ ]. archer and jacobson [ ] estimated that just only % of the global total wind power potential could account for as much as pwh ( . × gwh) of electricity annually equal to seven times total current global consumption of electricity (comparable to present global use of energy in all forms). by the end of , the worldwide wind capacity reached gw, there is more than gw of capacity were added during the year . the total worldwide installed wind capacity can now generate closely % of the world’s electricity demand [ ]. for new strategies of wind power, fig. shows the breakdown of power generation according to remap options in the power sector by , with the results of the remap countries scaled to the global level. in total, twh of additional power will be generated from renewable sources in . wind has the largest additional generation of about twh per year worldwide (three-quarters from onshore, a quarter from offhore) representing % of the total potential [ ]. in addition, the expansion of non-hydro renewables depends on subsidies that more than double to ; additions of wind & solar have implications for power market design & costs as shown in fig. [ ]. it is seen that for most developed country (europe, japan, and united states) will majorly focus on wind energy, whereas developing countries (india, latin america, asean and africa) will invest largely in hydropower because the capital cost of wind energy is a little bit higher than hydropower right now. to overcome this challenge, it is shown that the larger the turbine is the greener the electricity becomes. with an increased cumulative production of wind turbines, manufacturers gain experience with the technology, which is commonly reflected in a reduction of the investment costs [ , ]. therefore, there is also a trend showing an increase in the average wind turbine unit rating every year with the prospects of the higher than mw wind turbine project concept designs and installations for the coming decade [ ], it shows the trend of wind turbine getting bigger and bigger by the time. however, for wind turbine electric ratings higher than mw, its geometric dimensions and consequently the total weight of the generator increase exponentially. for this main reason, it is required to search for alternative technologies for offshore wind turbines with powers more than mw to achieve the electrical power with a lower electrical generator volume and a low total weight with reasonable costs. in this case, htsg is a best candidate because of their advantages mentioned above. fig. . energy demand growth by [ ]. fig. . global power generation by technology [ ]. fig. . renewable power up around the world [ ]. status of the technology development of large scale hts generators for wind turbine . an indispensable technology development of htsg wind turbine the hts material can permit higher magnetic flux and a unique higher current-carrying capability than that of low temperature superconductor (lts), so hts rotating machines provide the highest power density when compared with conventional ones. because of the significant increase in both electrical and magnetic loading, they are smaller and lighter in structure [ ] and have less energy consumption, leading to a reduced energy cost [ ]. however, there are three major challenges which must be addressed before a large scale utilization can be obtained. these challenges generally come from hts material challenges, cryogenic cooling system and hts field coil stability. . . hts coated conductor materials challenges first of all, it is the price of the superconducting wires. we can easily see that hts generator have a lower rate of refrigeration investment, refrigeration maintenance, least copper, magnetic field and structure material. the only thing is cost of superconducting material cost. if we can solve this problems, the hts generator will much higher efficiency than lts [ ] as shown in fig. . because of a huge progress has been made worldwide in increasing the length, performances, price trends for hts coated conductors in the last years and the achieved improvements in performance of hts coated conductors produced at an industrial basis, it is assumed that superconducting wire can be manufactured at a cost of less than $ /kam in the future, which means cost-performance (c-p) ratio of superconducting wires. it is estimated that this should occur in the time frame - and that by the price should already come down to $ - /kam [ ]. while sunam gives an achievable estimation to get the price reduce to $ /kam in next two years ( ), and smaller than $ /kam in years later [ ]. besides, between the two recent well-known hts coated conductors, ybco is the better one for design of htsg in cases of both mechanic stress and construction cost of htsg as we can see in fig. [ ]. furthermore, g hts wire at liquid nitrogen (ln ) can transmit with insignificant heat losses electric current density from – times decreasing heat losses compared to conventional copper conductor. in addition, the c-p ratio of g hts wire is $ –$ /kam, while copper wire has $ –$ /kam. c-p ratio of g hts wire is at the threshold of $ /kam being defined by the us doe for the ability for hts wire to compete with traditional copper electric wire. this makes g hts wire very efficient for hts cables and other electric engineering applications [ ]. although, g hts wire technology is still equivocal, we should believe the innovation of new technology based on genius contribution of scientists and researchers around the world. then, g hts technology will be commercial soon to serve as a new role for energy applications. . . reliability of cryogenic cooling system the second challenge is to demonstrate the reliability of the technology seen from a system perspective including the cooling technology. among particular sub-system: hts windings, electromagnetic shield, heat insulation, the cooling system is one of the important components of hts machines, of which function is to take heat away rapidly and maintain the superconducting property. therefore, the robust and reliable cooling system is required for hts machines to operate for a long time. relative to the development and improvement of hts machines, investigations on the cooling system are also enhanced. the recommended cooling methods for hts machines rotor are based on phase change heat transfer [ ]. for motors with low rotate speed, pipe evaporative cooling is strongly recommended as an innovative cooling to avoid low centrifugal acceleration. it has also been successfully applied to [ - ]. fig. . cost comparison of the designed lts and hts wind generator [ ]. fig. . growth trend in weight of conventional generators, and the weight of the mw scsg using ybco and bi wires [ ]. t. d. le, j. h. kim, s. i. park, d. j. kim, c. j. boo, and h. m. kim fig. . the principle operation of a stand-alone cryogenic cooling system using thermal trigger switches [ ]. as shown in fig. , a design of a stand-alone cryogenic cooling system for a -mw class hts rotating machine based on optimizing the thermal design and analyzing characteristics of using different types of solid cryogens. a high performance, reliability, and optimal cooling systems for off-shore wind turbine are characterized in [ ]. the device’s principle application is to eliminate parasitic heat loss from systems’ non-operating cryo-coolers. hence, it will optimize total volume of solid cryogens to remain in the hts field coils, which are kept in a cryostat, and are kept below a certain temperature as long as desired. it can utilize cryo-cooler redundancy and downplay the cryogen usage in dewar systems. because of the significant savings in refrigeration power, cryogen consumption can be achieved with a short investment return time period and at a relatively low cost. . . stability of hts magnets for field coil in cases of hts field coil stability, the hts wind turbine generator for large scale off-shore has two other crucial requirements in order to dominate wind power market compared with conventional large scale generators. those are ( ) improved operational robustness and stability, and ( ) compact and lightweight than conventional generator [ ]. the first one is a reliable and stable hts magnet used for rotating field coil. in general, hts magnets are thermally stable having stability margin times larger than lts magnets. in other words, hts magnets have slow normal zone propagation, if thermal heating at a local hot spot of magnet occurs, it is so difficult to detect quench and protect hts magnets [ ]. and also, hts magnets are operated in electromagnetically vulnerable conditions than conventional stationary hts magnet due to unexpected time-varying magnetic field by change of wind speed in real time [ ]. this means electromagnetically unstable operation of hts magnets for field coil brings out a local thermal heating and immoderate magnetic stress. as a result, quench and burn-out magnet arise. the second issue is a compact and lightweight hts magnet. in order to reduce the construction costs of wind turbine, it is essential to manufacture compact and lightweight generator as enhancing current density of hts magnet. and also compact hts magnets leads to stable operating condition thermally and mechanically. therefore, we should contrive novel design and manufacturing techniques in order to solve above technical issues. no and partial insulation (ni/pi) winding techniques can be considered as a way of hts field coil windings. these winding techniques are developed by mit’s francis bitter magnet laboratory and introduced and studied in [ - ]. the key benefits of ni/pi technique detail as follows: a) thermal stability enhancement, b) self-protecting, c) compactness (enhanced overall current density), and d) mechanical robustness compared with insulated counterpart. however, ni/pi techniques also have some challenges in wind turbine application as follows: a) unproven in a “large” racetrack coil, and b) charging delay. fortunately, pi technique can be possible to mitigate the adverse effect of the ni technique, which is charging delay without sacrificing the stability too much. there has already had a design and performance analysis of a ni-type to practical application for field coil of hts rotating machine [ ]. it shows that by applying ni technique the magnet quenched at a ( % higher than the designed quench current at a). moreover, it also indicates that when the ni-type hts field magnet current approaches its ic, resistance of the hts wire in the magnet increases and a portion of the power supply current starts bypassing through the other hts wire layer, which results in a reduction of the center magnetic field. hts rotating machine with ni-type hts magnets was successfully fabricated and tested in the operation current level of %. . technological issues for optimization hts generator design . . optimal operating temperature selection besides the three critical issues above, one more concern taking into account of a htsg design is the operating temperatures of hts windings. in the study of y. xu [ ], the operating temperature are extended from k to k. then, a preferable operating temperature is studied considering its influence on the basic performance and the cost of wind turbine htsg based on d magnetic flux density simulation, the influence of the operating temperature on field leakage coefficient, maximum field coil operating current, and refrigerator power was clarified. in addition, the basic performance, including the generator weight, the hts material length and the generator efficiency of wind turbine htsg at different operating temperatures was compared with that of wind turbine based on conventional generator. then, the wind turbine htsg cost was estimated and compared with that of wind turbine conventional generator. finally, it is found that the operating temperature of k is preferable in practical htsg application. status of the technology development of large scale hts generators for wind turbine . . . . . . g en er at or e ff ic ie nc y [% ] operating temperature [k] fig. . dependence of generator efficiency on the operating temperature [ ]. fig. . salient-pole iron rotor and magnetic stator teeth with back iron in cases of no load field distribution [ ]. . . generator topology design furthermore, a design topology for htsg is also a significant aspect. therefore, a concept design for an hts direct drive wind turbine generator various to five different topologies is described in [ ] – including ( ) rotor iron yoke and stator air gap winding with back iron, ( ) non-magnetic rotor yoke and stator air gap winding with back iron, ( ) rotor iron yoke and magnetic stator teeth with back iron, ( ) non-magnetic rotor yoke and ( ) magnetic stator teeth with back iron and salient-pole iron rotor and magnetic stator teeth with back iron in fig. . the main focus of this study was to minimize the amount and costs of the hts field coils based on mechanical and thermal design. final selection of the design is a trade-off between various performance metrics – quantity of hts, the lowest weight, structural supports and level cost of energy (lcoe), and option ( ) is a recommended selection. . . structural shape of field coil moreover, existing studies concerning electromagnetic characteristic for large scale htsg have been performed in [ - ]. one of significant research is the effect of field fig. . d magnetic field distribution for different field coil shapes (rectangular shape model) [ ]. fig. . linear trend line for superconducting machines (blue line) [ ]. coil shape. then, designs and simulations of a -mw-class hts generator with various superconducting field coil shape have been performed using d fea according to the structural-shape changes – rectangular shape, pyramidal shape and spreadable shape. from each comparative analysis result, it is confirmed the effects on the hts generator and field coil performance through function of inner radius (ri), thickness (tc), and height (hc) and determine the effects of the air-gap shape change and the spreading dp coil arrangement. it is indicated that the optimal analysis results on the generator induced voltage in rectangular shape design, which has the largest ri and generates the largest induced voltage and lowest magnetic flux density in the superconducting field coil [ ]. table i recent htsg conceptual design [ ]. company model power (mw) status/year azimut concept/ ge concept/ amsc sea titan prototype/ technalia suprapower concept/ superpower react concept/ t. d. le, j. h. kim, s. i. park, d. j. kim, c. j. boo, and h. m. kim . . level cost of energy (lcoe) one more technological issue, according to [ ], it has presented results of generator design optimization using lcoe as a measure of the best design. the results presented here use monte-carlo design space exploration to randomly vary the generator parameter values and the best topology selected. the results showed that there is an optimal hts length such that if the conductor length was increased or decreased, would result in a non-optimal lcoe. lastly, table i shows a huge number of existing projects related to electrical generators applying high temperature superconducting technology. the most relevant projects and designs of hts generators specifically for offshore wind power systems are presented in [ ]. it is also consolidated by the development trend of superconducting machines as shown in fig. . . conclusions with the brief review of g hts material trends, we hope that the prices of production will be reduce. even though, the possibility of g hts we can be believe that the innovation of g hts can solve the biggest problems with htsg design. in addition, based on a great number of simultaneous researches related to large scale of htsg, this paper restates some significant works optimizing not only on the htsg field coil stability various on d simulation of field coil shape, design topologies, different materials, operating temperature but also on correlation between htsg cost and level cost of energy, as well. finally, the latest updates for selected projects will consolidate completely the potential alternative of htsg for their contribution to energy crisis. it also shows that many researches, prototypes, even commercial yield will dramatically increase on this technology in near future. acknowledgment this research was supported by the scientific promotion program funded by jeju national university. references [ ] f. manzano-agugliaro, a. alcayde, f. g. montoya, a. zapata-sierra, and c. gil, “scientific production of renewable energies worldwide: a overview,” renew. sust. energy rev., vol. , pp. - 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[ ] y. nyanteh, n. schneider, d. netter, b. wei, and p. j. masson, “optimization of a mw direct drive hts generator for minimum levelized cost of energy,” ieee trans. appl. supercond., vol. , no. , p. , . wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ microsoft word - mandm- - .doc atomic resolution investigation of metal-assisted hydrogen storage mechanisms in activated carbon fibers c.s. bonifacio,* a.m. thron,* s.j. pennycook,** c.i. contescu,** n.c. gallego,** and k. van benthem* * department for chemical engineering and materials science, university of california, shields ave., davis, ca ** oak ridge national laboratory, materials science and technology division, bethel valley rd., oak ridge, tn hydrogen attracts an interest as alternative future energy carrier to overcome the foreseeable energy crisis. solid state storage media, however, are not yet providing sufficient cyclic gas uptake capabilities. promising candidates for hydrogen storage media are pd-modified activated carbon nanofibers (acf). during synthesis, thermal activation processes introduce micro- and nanoporosity into the acf microstructure. it has been shown that modification of carbon structures with pd nanoparticles enhances the hydrogen storage capabilities [ ]. however, it was found that the hydrogen gas uptake exceeds the expected storage capabilities based alone on pdh formation and physisorption on unsaturated carbons (figure ). high-resolution tem and aberration-corrected stem was used to identify local storage sites and mechanisms in the acf microstructure. hrtem imaging is very sensitive to the atomic structure of the carbon fibers. recorded micrographs show some degree of ordering in the acfs with a large number of quasi-parallel grapheme sheets (figure c). the termination of graphene layers creates small open volumes in the microstructure with diameters of the order of - Å [ ]. such nanoprosity was found to be highly efficient for the physisorption of hydrogen atoms. we have used hrtem to quantitatively identify such re-occurring structures. in addition, selected area diffraction is used to determine the crystal structure and lattice constants of pd particles embedded in the acf microstructure. the simultaneous acquisition of bright field (bf) and high-angle annular dark field (haadf) images using aberration-corrected stem enables the correlation of the carbon microstructure (as recorded in the bf image, figure b) with the location and atomic structure of pd nanoparticles as identified in the haadf image (cf. figure a). especially the atomic and electronic structure of the pd/acf interface is critical for hydrogen storage mechanisms with respect to h dissociation by the pd particle and subsequent storage in the acf microstructure close by (the so-called spill-over effect) [ ]. sub-Ångström imaging conditions enabled the detection of highly dispersed single pd atoms in the volume of the carbon fibers. the presence of single pd atoms stabilized by the acf template might enable the formation of kubas-like complexes [ ] and hence reversible storage of up to six hydrogen atoms per pd atom. we are currently planning to use in-situ hrtem to image potential changes in the carbon microstructure and the pd particles due to exposure to hydrogen gas, which will offer more detailed information about the hydrogen storage mechanisms. microsc microanal (suppl ), copyright microscopy society of america doi: . /s https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s https://www.cambridge.org/core https://www.cambridge.org/core/terms [ ] n.c. gallego et al., extended abstract to carbon ’ international carbon conference, aberdeen, scotland, july - , [ ] r.s. aga et al., phys. rev. b , , . [ ] a.d. lueking et al., appl catal a: general , , - [ ] g.j. kubas et al., j. am. chem. soc. , , - [ ] financial support came from the university of california at davis and from the u.s. department of energy, basic sciences, division of materials science and engineering figure : sem micrograph (a) of activated carbon fibers with added pd catalyst particles (bright contrasts). (b) hydrogen adsorption isotherms for pd-free and pd-modified acf ( . wt% pd). the dashed line represents the amount of hydrogen required to convert the entire pd content to palladium hydride (β- pdh . ). (c) hrtem micrograph of pd-modified activated carbon fibers. some degree of ordering is observable within the carbon microstructure. figure : adf (a) and bf (b) images recorded from an activated carbon fiber with highly dispersed single pd atoms, which are encircled in red. their location was also marked in the bf image (b) microsc microanal (suppl ), https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s https://www.cambridge.org/core https://www.cambridge.org/core/terms << /ascii encodepages false /allowtransparency false /autopositionepsfiles false /autorotatepages /none /binding /left /calgrayprofile (dot gain %) /calrgbprofile (srgb iec - . ) /calcmykprofile (u.s. web coated \ swop\ v ) /srgbprofile (srgb iec - . ) /cannotembedfontpolicy /error /compatibilitylevel . /compressobjects /tags /compresspages true 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cng load shedding on daily routine: a study of pakistan muhammad arslan , *, rashid zaman , r. k. malik bahria university, po box , e- , islamabad, pakistan *tel: head of campus, shaheed zulfiqar ali bhutto, institute of science and technology, islamabad, pakistan *e-mail address: muhammadarslan @gmail.com abstract people of pakistan are facing a number of problems due to cng load shedding. this study investigated the consequences of energy on routines of people and also on social and economic performance of people. primary data has been collected by conducting video recorded interviews and comment based interviews from twin cities i.e. islamabad and rawalpindi of pakistan. the sample of study includes students, housewives, businessmen and professional workers who are affecting by this cng shortage. this study focuses on relationship between cng shortage and its effect on daily routine life and performance of people. it also focuses on psychological issues as well as the economic issues that are caused due to this shortage. this study utilizes in depth semi structured interviews to conduct the qualitative study. n-vivo is used as tool of data analysis. the cng shortage in pakistan caused many critical issues like unemployment, decrease in export contracts and commodities prices are increasing due to this shortage. less working hours, lack of social and family gathering, increase in work load, depression and anxiety are results caused by cng shortage. it is concluded that cng shortage has bad impact on people’s lives and on their overall performance. keywords: pakistan; cng shortage; energy; n-vivo; commodities . introduction . . background of study the price of international trade oil that took place during the last three or four decade gave ascend to prevalent problems of economic and energy adjustments throughout the world. the beneficiaries of this rise in prices of oil are oil exporting countries. the demand of energy also plays crucial role in changing the energy prices. the coupling of economic system and energy system led to increase in inflation and almost every aspect which was related with energy has affected tremendously. energy means ability to do work. shrinkage in existing resources, recent rise in energy prices and energy conservation technologies have brought the importance of energy use and economic growth in focus. the input of energy to the output of industrialized countries is a divisive topic in economic theory. the initial works of some authors left no room for doubt about the importance of the energy factor in productivity (rosenberg, ; schurr, ). international letters of social and humanistic sciences online: - - issn: - , vol. , pp - doi: . /www.scipress.com/ilshs. . cc by . . published by scipress ltd, switzerland, this paper is an open access paper published under the terms and conditions of the creative commons attribution license (cc by) (https://creativecommons.org/licenses/by/ . ) https://doi.org/ . /www.scipress.com/ilshs. . energy is the major and most critical input of any production activity. expansion in energy and its resources can lead to higher growth and shortage of this energy may lead to shrink in growth. over the last three or four decades the overall world economy has bearded many swings in energy prices. these swings have very upshot for under developed countries of asia and also on other countries. many researches showed that, after a decade of oil worries, consumers and their government should also find delight in today’s oil market (gravin, ). in small countries like belgium which are suffering with declining coal industry and denmark with its scarce energy output, have responded to transformation of world energy economy over the last one decade (michael, ). like other countries california has been tormenting scarcity of resources through the nineteenth century (james, ). the resources of coal have proved as lower quality. the wood was depleted due to convenience of urban areas. in early s the economies of western europe had become heavily dependent upon imported oil. the opec induced price rises from two to thirty dollars per barrel between and early s. in bangladesh, about three to fourth of total consumption of primary source of energy is from the firewood and crop residues. if the swiftly growing economies of pakistan, india and china don’t plan then it can face severe energy crisis. few researches also showed that china is in the process of industrialization and electricity is pre-requisite for rapid growth. at the same time, the “coal- based” energy structure in china will not change perennially, which means, the enlargement of power industry will be focus theme to the constraints of resources and environment for a long period of time. therefore, according to the development of electric power industry, energy saving and emission reduction will be an endless theme (kou, ). findings of some researchers showed that there was positive relationship between consumption of energy and exports of country. it has also other effect on other hand because if the exports increased, it increased the level of energy consumption (li, ). eleventh five year report of india showed that india was major consumer of energy. india also has world ranking in energy producing, it has seventh rank. the . % of total annual energy production was from india ("eleventh five year plan," ). some authors employed an integrated assessment in an effort to compare the effectiveness of prospective policy options to tackle a range of energy and an environmental issue which couples a technology-rich bottom-up model of the u.s. electricity sector with a fully dynamic forward-looking general equilibrium model of the u.s. economy. the model provided a distinctive and steady modeling framework for energy and environmental policy analysis. though energy efficiency standards are found to be the least cost-effective at reducing energy usage or mitigating carbon emissions, their appeal is likely to rest on assumptions about specific market failures or on political factors (yuan, ). currently, pakistan has been suffering energy shortage due to inappropriate decision making, incapability of government and deteriorated laws. as a result, whole economy is suffering i.e. industry, commercial exports, domestic life and local businesses of pakistan. the problem has not been addressed yet and it is becoming challenging for any government to fulfill the energy demand in near future. from last one decade people of pakistan were tormenting from electricity shortfall but due to inappropriate policies, people are now besieged for gas shortages as well. amplified use of enhanced energy sources helps people in humanizing the quality of life, saves time and environment. this usage of energy also humanized the delivery of social services. the easy availability of better quality fuel improves the lives of females and children who used traditional method of fuel like gathering of wood. in pakistan, gas is the one of the most important source of energy. pakistan is the world international letters of social and humanistic sciences vol. largest user of gas as fuel in public and private transport with . million vehicles (zaid, ). as compared with prices of other sources of fuel like petrol, the price of gas was half. there was found burgeon growth of cng stations throughout the country especially in punjab region. although the government is now annoying to reduce the gap between gas and petrol prices but government is incapable to meet the demand of gas for industry. countless industries are being shut due to gas shortage. this shortage forced a number of textile units to close down due to delay in fulfillment of their export consignments (jamal, ). some studies showed that lack of integrated planning, non-utilization of local resources and imbalanced energy mix were major causes of energy crisis in pakistan (ahmad, ). now in current situation it has become a serious matter of daily routine life due to unannounced cng load shedding and low pressure of gas. moreover, it has also been reported that in many small cities and towns of pakistan, the commodity continues to disappear for many hours before any prior information of this load shedding. thus the public and private transport is affecting and ultimately domestic users, professionals and students are also. all pakistan cng association (apcnga) on january , staged a protest demonstration and sit in against the prolonged and unannounced gas load shedding in front of parliament. transport unions of twin cities of islamabad and rawalpindi also participated in this sit in. the protesters demanded that government should exempt the cng sector from gas load shedding because most of the transport was running on cng (apa, ). this qualitative investigates the problems and issues that arise from this unannounced close down of cng stations and cng shortage. this study also determines the effect of these energy crises on daily routine life of people. these issues include daily routine life factors which are affecting from this shortage. psychological and social issues are also investigated in this study. due to critical relationship of energy and growth of economy, issues that can affect the economic situation of country are also addressed in this study. . methodology . . research design the research design of this qualitative study was iterative. it means research questions are adjusted to what is learned from respondent. in this research design there is effect of participant responses, how and which question researcher would ask to next (field guide). research design must be responsive with the context (richards, ). . . sample in this study the purposeful convenient sampling technique was used. this technique was useful when data was collected from those respondents which gave you in-depth and relevant data (harms, jack, ssebunnya, & kizza, ). the sample of this study includes daily users of transport that are running on cng. the sample size in this study was respondents. these respondents included students, house wives, businessman and drivers of public transports. ilshs volume . . context the context of this study was the providers of compressed natural gas (cng) located in territory of islamabad. these included the crowded cng stations in the twin cities of pakistan. . . collection of data in this study the video recorded semi- structured interviews were conducted for data collection. this method is optimal when you want to get in depth information about an issue. in-depth interviews are less structured than semi-structured ones and may cover only one or two issues. this type of interview is used to explore in detail the respondent’s own perceptions and accounts. interviews were started by some open questions and then some questions related to topic or issue that was under investigation. the qualitative interviews were scheduled at that time when users of cng were waiting for their turns to fill tank for many hours. each interview lasted from - minutes. . . data analysis the computer software qsr nvivo was used as tool for analysis of data. in nvivo, all data were imported then transcribed data into textual form for analysis. after transcribing data, explored the themes and code them. for the coding of date, auto coding method was used and then converted this data into nodes. after it classification of data, queries were run for generating the word frequency and tree map of data. at the end, model of study was generated by selecting all themes which were coded into nodes. there was used content analysis due to exploring nature of study. after applying the analysis these results were exported to some other destination and saved them. . results . . word frequency of study the figure showed the word frequency of present study in graphical form. in the figure there was shown the weight-age percentage of word that was used frequently. there was also shown the count of repeated words and also the length of the frequently used words, it could be seen that the word cng was repeated about times in this study. the word transportation was repeated times in this study. the word routine, useless, difficulty and earnings were repeated times in this study. this study consisted of respondents but the frequency of words was more than the respondents. it meant that some respondents used these words more than one time. from the above figure it could be interpret that cng shortage had been created a lot of problems and it has affected their routine life tremendously. . . text query figure showed that due to this unannounced and shortage the efficiency and productivity level of employees, students and households are decreasing day by day. due to this energy crisis there were increasing complaints for low level of performance. figure shows the impact of cng shortage and its impact on working and studying life of employees and students. due to this draw back the work load has increased many folds and studying hours of students has been affected immensely. wastage of time has been increased. international letters of social and humanistic sciences vol. in figure , there were many psychological issues which are flourishing due to cng shortage. these factors included tension, stress, depression and anxiety. these factors have been affecting life of and have bad impact on their health. . . tree map of study the figure shows the tree map of cng load shedding and its impact on daily routine life of people. a tree map was that which shows the cause and effect relationship of something. in above tree map there was showed the relationship of cng shortage and the factors which were affecting from this shortage in any aspect. it also showed the problems and issues that have been arisen due to this unannounced shortage. it showed that routine life of people has been effect immensely. the economic as well as social and family life of people has been affected to an extent. it has been badly affecting the working and studying hours and also the career of students. due to this shortage prices of commodities have been increased many folds. cng shortage has impact on many aspects these aspects includes daily routine life of people, their performance at office and at class room. this energy crisis has been affecting the household’s wives and it increased their problems. it has been also affecting economic life of people and economic condition of country. it has lowered the per capita income of the people of pakistan. this shortage has created transportation cost and due to this increase in transportation cost, the earnings were lowered day by day and prices of commodities were increasing day by day. the most of people of twin cities of islamabad and rawalpindi tended to use public transport due to huge difference between cng and fuel prices. as a result of this trend the earnings of the van and taxi has been lowered. . . model of study figure showed the whole model of this qualitative study. this model was created by using nvivo as tool. in this model only those issues and problems were included which was repeated by every respondent and important in nature. in this figure all the problems and issues which were caused due to cng shortage. in this study there were aspects which were affected by this energy crisis. the effect of cng shortage on daily routine life, performance, psychological factors and economic problems were also shown in figure. in the above diagram there were parent and child relation between the nodes. there were four children of cng shortage i.e. effect on daily routine life, economic condition, effect on performance and psychological issues raised from cng shortage. due to cng shortage, working and studying hours were badly affected; social and family were affected immensely. the productivity and efficiency of the businesses, employees and students were decreased due to this cng shortage. economic condition of country was also affected by this shortage because of not fulfillment of export contracts. unemployment rate was also increased because many textile and other industries shut down their businesses due to unannounced close down of cng. because there was big difference between cng and petrol prices, transportation costs increase many times and due to this price of commodities were also increased and economic life of people were going worst day by day. cng shortage increased the issue of people i.e. increase in work load, time wastage and it was also affecting their social and family life. some people said that keeping in line and wait for fuel, borders them. ilshs volume . . matrix representation figure showed the cng shortage and its impact on daily routine life of people. cng shortage was on right side in this picture and all the issues which were generated due to this shortage were at the bottom of diagram. these all issues were numbered from a to t. their names were mentioned on diagram. it meant that about issues were important which were caused due to cng shortage. these were those issues which were repeated and have significant importance on life of people. fig. . graphical representation of word frequency. fig. . text query for relationship of cng and efficiency. international letters of social and humanistic sciences vol. fig. . impact of cng on working and studying hours. fig. . psychological issues due to cng shortage. ilshs volume fig. . tree map of cng load shedding and its impact on daily routine life of people. international letters of social and humanistic sciences vol. fig. . model of the study. ilshs volume fig. . matrix representation of cng shortage and its impact on daily life of people. . discussion the findings of present study were well supported by previous studies. the data was collected from respondents at cng stations. interviews were conducted when people were waiting in line for many hours to fill their car gas tanks. many researchers have conducted empirical studies on energy issues in many countries but few have considered qualitative aspect of these issues (ahmad, ; gravin, ; james, ; rosenberg, ; schurr, ; yuan, ). many researchers found that energy crisis has increased the economic issues in the country which was suffering from crisis (yuan, ). . conclusion it was concluded from the results of this qualitative study that energy played an important role in growth and life style of people of that country. if the country was suffering from energy crisis, it creates severe issues for the life of people of that county. the result of study showed that due to cng shortage the daily routine life of people were affecting immensely, their routine became disturbed, work load was increased and studying and working hours were also decreased. performance and efficiency of industries and employees were decreased day by day. social gathering of people was also affected due to this shortage. people reached late at night and could not spend time with their family. , , , , , , , , , : cng shortage : cng shortage international letters of social and humanistic sciences vol. limitations there are few limitations of this qualitative study. the sample size was small due to time constraint. more analysis methods could be used for analysis of data like e-views and spss. the study could be conducted in other contexts. recommendations it was recommended that the government should focus on this energy crisis. if this issue was not resolved on time it could create more severe results on economic condition and life of people. government should make new policies about energy crisis according to need and demand of people. government should adopt alternative energy resources to fulfill the need of society. references [ ] ahmad m., b. ( ). moving towards energy sufficiency, sustainability, and sovereignty. emr-consult. [ ] apa. ( ), from http://apcnga.org/newsdetail.php?netwire= eleventh five year plan. ( ): planning commission of india. [ ] gravin j., clifton c., journal of business strategy ( ) ( ) - . [ ] harms s., jack s., ssebunnya j., kizza r. ( ). the orphaning experience: descriptions from ugandan youth who have lost parents to hiv/aids. harms et al. child and adolescent psychiatry and mental health, ( ). [ ] jamal j. ( ). gas load shedding hits consumers hard. islamabad. [ ] james c., williams. ( ). fuel at last: oil and gas for california, s- s. california historical society ( ) - . [ ] kou b., et al., international journal of business and management ( ) ( ). [ ] li l., international journal of business management ( ) ( ). [ ] michael s., geography ( ) ( ) - . [ ] richards. ( ). qualitative research design. thinking research. [ ] rosenberg n. ( ). the effects of energy supply characteristics on technology and economic growth. in s. schurr,s. sonenblum and d.o. wood, eds, energy, productivity, and economic growth. cambridge university press. [ ] schurr s. ( ). energy efficiency and economic efficiency: an historical perspective. in s.schurr,s. sonenblum,d.o. wood, eds., energy, productivity, and economic growth. cambridge university press, cambridge, mass. [ ] yuan m., et al. ( ). policy effectiveness in energy conservation and emission reduction. the quarterly journal of the iaee's energy economics education foundation, (special). [ ] zaid k. ( ). an insight to energy crisis. islamabad: insaf research wing. ilshs volume transport of ocean sediments by debris flow: abstract; significance of thin carbonates in interpreting depositional environments of thick clastic sequences: abstract; exploration and development of natural gas, - : abstract association round table photographs taken from orbital altitudes. sufficient rel- atively high-quality space photography is available to permit evaluation of selected areas offering a broad spectrum of structural complexities, rock types, and geographic locations. an important aspect of hyperalti- tude photography is the synoptic overview of large areas without regard to natural and artificial bounda- ries. this type of view will prove quite valuable in re- gional geologic studies and the planning of exploratory programs. many difficult geologic problems in one area may easily be solved by comparison with another area where the critical relations are exposed. certain elec- tronic image enhancement techniques may prove to be a valuable aid in the interpretation process, especially for the erts imagery. the erts program scheduled for will furnish imagery with a ground resolution of - ft. the skylab program in will pro- vide the geologist with excellent color photography with - -ft resolution of large areas between the th parallels. space photography should yield impor- tant data which will result in a much better under- standing of such things as major tectonism, continental drift, nearshore deposition, and comparative geology on a global scale. hampton, m. a., dept. geol., univ. rhode island, kingston, r.i. transport of ocean sediments by debris flow debris flow, a gravity-transport mechanism com- monly observed on land, may be a significant agent of high-density mass transport of sediment in the oceans. debris flow is distinguished from other mass-transport agents by the mechanism of support of granular solids in the flow. support is provided mainly by the strength of the debris, but also by buoyant forces. strength is derived from the fluid phase of the debris (clay miner- als plus water), which acts as a plastico-viscous mate- rial. suspension of granular solids by this mechanism does not depend on flow conditions and occurs if the debris is moving very slowly or even not at all. move- ment of a debris flow depends on a critical thickness of the debris as well as the internal-friction angle. the slope angle required for debris flow typically is less than the - ° required for normal grain flows or avalanching. thus, debris flow may carry large amounts of sediment in suspension while moving slug- gishly down a gentle slope. the amount of clay, rela- tive to granular solids, necessary completely to support sand-size material is on the order of % or less. thus, sandy debris-flow deposits may be texturally similar to current-deposited sands. hanley, j. h., dept. geol., univ. wyoming, lara- mie, wyo., and e. f. pearson, dept. geol., univ. pacific, stockton, calif. significance of t h i n carbonates in interpreting deposmonal environments of thick clastic sequences when interpreting depositional environments of domi- nantly clastic sequences, thin carbonates, if present, of- ten are overlooked or given short shrift. detailed study of the carbonates, however, can be instrumental in en- vironmental interpretations of enclosing elastics. this is particularly true if the clastic units lack fossils or envi- ronmentally significant sedimentary structures. this hy- pothesis is supported by examples from pennsylva- nian and permian strata of southeastern wyoming. the permian goose egg formation consists of thick, red siltstone and mudstone with interbedded thin, widespread carbonates. the clastic units have been interpreted by various workers as deep-water ma- rine, shallow marine, deltaic, specialized marine, or continental deposits. petrographic examination of the carbonates suggests that they were deposited in shallow subtidal, intertidal, and supratidal environments. the facies mosaic exhibited by the carbonates suggests that enclosing siltstone and mudstone were deposited in nonmarine environments. festoon cross-stratified sandstone which character- izes the casper formation (pennsylvanian-permian) in the extreme southern laramie basin has been inter- preted as marine, subaerial, or fluvial in origin. car- bonate beds in the casper formation are thin, lenticu- lar lithosomes of limited geographic extent. petrologic studies of these limestones suggest that they were de- posited in small lakes or ponds which periodically were emergent. the inferred environment of carbonate deposition supports a subaerial dune environment for the festoon cross-stratified elastics. hardin, g. c , jr., ashland exploration co., hous- ton, tex. exploration and development of natural gas, - the energy crisis in the united states has been mak- ing headlines for more than years. most energy mate- rials are expected to be in short supply, but the short- age of natural gas is recognized as being most critical. liquefied natural gas and coal gas wfll supply a part of the demand but most of the new gas required must result from domestic drilling. an all out effort must be made to discover and develop the , trillion cu ft of gas estimated by the potential gas committee to re- main undiscovered in the united states. cost of finding and developing this new gas might well be in the same range as the estimated cost of lng and coal gas. compensation for today's higher risks and higher costs must be provided by incentives in the form of tax credits and higher wellhead prices. a graduated wild- cat-well tax credit, similar to the now repealed invest- ment tax credit, may be the way to encourage the drill- ing of the higher risk new-field wildcats required to discover the gas that the country will require during the next decades harris, w. h., and t. k. guha, dept. geol., brooklyn college, city univ. new york, brooklyn, n.y. coprecipitation of strontium and magnesium with holoceni- cave calcites, barbados, west indies within stalactites from barbados caves, progressively younger calcite conical growth layers and central canal void-filling calcites contain smaller amounts of sr and mg. the observed distribution of sr and mg in the stalactites is in agreement with a solution-reprecipitation model in which calcite-to-calcite transitions within a low-mg calcite vadose zone yield amounts of sr and mg decreasing with time to vadose water seeping into ventilated cavern macropores. within the overall trend of decreasing sr and mg content, vadose seepage and speleothem calcites may become locally enriched in sr and mg when ( ) the groundwater temperature de- creases, thus affecting the temperature dependence of the ealcite-water distribution coefficients for sr ( . ± . at °c) and mg ( . ± . at °c), or ( ) mete- oric waters bypass the upper vadose zone to dissolve low mg calcites of higher sr and mg content in the american journal of electrical and electronic engineering, , vol. , no. , - available online at http://pubs.sciepub.com/ajeee/ / / © science and education publishing doi: . /ajeee- - - energy crisis in nigeria: need for renewable energy mix tunde olaoye , titilayo ajilore , kunle akinluwade ,*, femi omole , adelana adetunji department of manufacturing services, prototype engineering development institute, ilesa, nigeria department of physics and solar energy, bowen university, iwo, nigeria department of research and development, prototype engineering development institute, ilesa, nigeria department of technical services, prototype engineering development institute, ilesa, nigeria department of materials science and engineering, obafemi awolowo university, ile-ife, nigeria *corresponding author: jakinluwade@yahoo.com abstract nigeria is endowed with oil and natural resources but the country cannot be said to have ever had adequate supply of electricity in the history of its electricity generation. this might get worse, as the country’s population increases and economic development is calling for more demand of energy. the gradual diminishing of fossil fuels and the effort to save the eco-system from global warming has seen nations turning to alternative sources to meet their energy demands. it is therefore, imperative that renewable energy solutions be proffered to cater for nigeria impending industrialization and its energy crisis which leaves many industries running at high cost and keeps many private homes in blackout. this paper discusses the potentials of renewable energy as an additional generation source to meet the energy demand of nigerian populace. it focuses on the country’s energy crisis and how its natural resources can be harnessed to meet the nation’s energy demand while reducing global pollution. an analysis of projected energy capacities from the abundant renewable energy resources and how much of these resources are required to be harnessed in the proposed energy mix- to achieve over , mw of power- was presented. keywords: energy crisis, nigeria, renewable energy cite this article: tunde olaoye, titilayo ajilore, kunle akinluwade, femi omole, and adelana adetunji, “energy crisis in nigeria: need for renewable energy mix.” american journal of electrical and electronic engineering, vol. , no. ( ): - . doi: . /ajeee- - - . . energy crisis in nigeria: an overview the first electricity supply company in nigeria was established in , though history has it that electricity generation in nigeria started around . it was in that all isolated electricity generating corporations in nigeria were merged with niger dams authority which was the only hydroelectric power station as at that time. the merger was named; national electric power authority (nepa). in the federal government of nigeria initiated the electric power sector reform act (epsra) after amending the electricity and nepa laws which were the prevailing laws as at . the amendments were to remove nepa’s monopoly and encourage private sector participation, albeit there were no tangible results. the reform for the sector was revived in with the power sector reform roadmap, which is successfully being implemented despite some challenges. the power sector reform has led to the unbundling of the power holding corporation of nigeria (phcn) into different companies - distribution companies, generation companies and transmission company [ ]. the international standard industrial classification [isic] is a united nations system for classifying economic data, according to category e division . the electricity statistic includes generation, collection, transmission and distribution of electric energy for sale to all categories of consumers [ , ]. on the other hand, in nigeria, this information can only be obtained from phcn publication in its annual reports and accounts. nigeria electricity consumption per capita between the and is kwh which is less than half of ghana and incomparable to united states with per capita of , kwh [ ]. energy crisis in nigeria has been a concern for both the nigerian government and the people for the past four decades [ ]. while other countries with similar problems have long overcome the predicament, nigeria still looms in pitch darkness. businesses have relocated from the country due to inability of the national power supply to meet their demand while homes have had to adapt to the epileptic power supply or in some cases total blackout [ ]. the few companies operating in nigeria largely depend on the off-grid supply using diesel/gas/petrol-powered electric generators thereby running at huge overhead costs and contributing to greenhouse gas pollution among other harmful environmental problems. according to the director-general of centre for management development, dr kabir usman, at the launch of the national power training institute of nigeria graduate skills development programme in abuja in , million nigerians spend n . tn on generators annually. american journal of electrical and electronic engineering in the world ranking of environmental pollution, nigeria’s category is low compared to world leaders like usa and great britain [ ]. this could be attributed to low level of industrialization in the country owing to the energy crisis being discussed. the question raised in our minds is how the energy crisis in nigeria can be solved whilst taking into consideration environmental conservation initiatives. if renewable energy is added to the present energy supply, more than sixty thousand megawatts ( , mw) or sixty gigawatts ( gw) of power required to place nigeria in the category of industrialized nation can be achieved without significant increase in environmental pollution. the poor electricity production in nigeria is a major contributor to the poor industrial development in the country who is renowned to have the lowest electrification per capita in africa. in nigeria, electricity generation, transmission and distribution account for less than one percent (< %) of its gdp but fifty-four percent ( %) of the share of utilities (e.g. electricity and water supply) [ ]. the electrification rate in nigeria is estimated at forty one percent ( %) [ ], indicating that the demand far outweighs the supply. the federal government is deeply concerned about this problem and has made several concerted efforts to increase electricity production in nigeria. the government has made it an objective to increase the current electrification rate from forty one percent, %, ( , mw) to fifty percent, %, ( , mw) by . it has a target of increasing electricity production to , mw by the year [ ]. table . power generation companies in nigeria with on-grid license from nerc and their installed capacities [ , ] name site location type installed capacity (mw) available capacity aes nigeria barge limited thermal afam power plc afam rivers state thermal . agbara shoreline power limited agbara ogun thermal alaoji generation company limited (nipp) alaoji abia state thermal anita energy limited agbara lagos state thermal azura power west africa limited ihovbor benin, edo state thermal benin generation company limited ihonvbor edo state thermal calabar generation company limited calabar cross state thermal century power generation limited okija anambra state thermal enersys nigeria limited ado ekiti state thermal delta electric power limited oghareki etiope west lga thermal dil power plc obajana kogi state thermal egbema generation company limited egbema imo state thermal egbin power plc egbin lagos state thermal energy company of nigeria (negris) ikorodu, lagos state thermal enersys nigeria limited ado ekiti ekiti state thermal ethiope energy limited ogorode, sapele delta state thermal farm electric supply limited ota-ogun state thermal first independent power company limited omokun rivers state thermal first independent power company limited trans amadi, rivers state thermal first independent power company limited elewe, rivers state thermal fortune electric power company limited odukpari, cross rivers state thermal gbarain generation company limited gbarain, bayelsa state thermal geometric power limited aba, abia state thermal geregu power plc (bpe) geregu kogi state thermal hudson power ltd. warawa, ogun state thermal ibafo power station ltd. ibafo, ogun state thermal ibom power ltd ikot abasi akwa ibom state thermal ics power ltd alaoji, abia state thermal isolo power generation ltd. isolo, lagos state thermal jbs wind power ltd. maranban pushit, mangu, plateau state wind kainji hydro electric plc (kainji station) kainji, niger state hydro kainji hydro electric plc (kainji station) jebba, niger state hydro knox j&l energy solutions ltd. ajaokuta, kogi state thermal lotus & bresson nigeria ltd. magboro ogun state thermal mbh ltd. ikorodu lagos state thermal minaj holdings ltd. agu-amorji nike enugu east lga, enugu state thermal nigeria agip oil ltd. okpai delta state thermal nigerian electricity supply corporation (nigeria) ltd. (nesco) bukuru, plateau thermal notore power ltd. onne, rivers state thermal ogorode generation company ltd (nipp) ogorode delta state thermal olorunsogo generation company ltd (nipp) olorunsogo, ogun state thermal olorunsogo power plc (bpe) olorunsogo, ogun state thermal omoku generation company ltd. omoku, rivers state thermal omotosho generation company ltd. omotosho ii ondo state thermal omotosho power plc (bpe) omotosho ogun state thermal paras energy & natural resources development ltd ogijo, ogun state thermal sapele power plc sapele, delta state thermal shell petroleum development company ltd. afam vi thermal shiroro hydro electric plc shiroro, niger state hydro supertek electric ltd. ajaokuta, kogi state thermal supertek nigeria ltd. akwete, abia state thermal ughelli power plc. ughelli, delta state thermal western technologies & energy services ltd. sagamu, ogun state thermal zuma energy nigeria ltd. (gas plant) ohaji egbema, owerri, imo thermal zuma energy ltd. (coal plant) itobe, kogi state thermal total , . american journal of electrical and electronic engineering the installed capacities of various power generation companies in nigeria and the summary of a typical national daily operational report are shown in table and figure respectively. figure . summary of national daily operational report of may , [ ] . renewable energy solutions . . solar energy energy from the sun is the primary source of energy for all surface phenomena and life on earth. solar energy is transferred to the earth through radiation and the energy reaching the top of the earth’s atmosphere is estimated at watts/m . it is used directly for a wide range of human life activities including simple domestic use - drying cloths, crop and providing hot water for home use; commercial generation of electricity using photovoltaic equipment; and heating water to drive turbines in thermal electric generators. the history of solar energy being used to generate electricity using photovoltaic cells can be traced back to when william grylls adam and his student richard evans day discovered that solid material – selenium – produced electricity when exposed to light. selenium photovoltaic cells were converting light to electricity at about to percent efficiency. in recent times photovoltaic cells are used to convert sunlight into electricity with percent efficiency. another method of using solar energy to generate electricity also used in recent times is to convert the sun’s energy into heat which is then stored in thermal tanks. the thermal tanks contain molten salts or paraffin wax which can absorb tremendous amount of heat energy without changing state. the heat is then used as a heat source in steam engines to drive electric generators. such thermal tanks usually have capacities of up to . terajoules per m . grid – tie allows excess energy to be sent to the transmission grid, the rest of the electricity can either be stored or used directly with solar inverters for ac loads. solar energy that falls on the earth in one hour can be approximated to the amount of energy that is needed on earth in a year. this energy source therefore holds a very great potential if properly harnessed. . . wind power wind power is the energy derived from wind to produce mechanical energy or electricity. electricity is generated from wind energy using windmills or ship sails. the windmills provide the power for different purposes like pumping water, grinding grains, and so on. the windmills have evolved over the years into wind turbines which are used to convert the kinetic energy in wind into electric power. the effect of wind on the turbine blades produces a rotational force which is transferred to the gear train connected through a shaft arrangement. the output from the gear train is connected to the generator that produces electricity. the use of wind for electricity generation can be traced back to by prof james blyth and since then different improvements have been developed. wind energy is a sustainable energy as the earth can never run out of wind. the quantitative measure of the wind energy available at a location is referred to as wind power density (wpd). it is a calculation of the mean annual power available per square meter of swept area of the turbine. a collection of wind turbines in a particular area is referred to as a wind farm. when it is erected on landed areas it is called on-shore wind energy electricity generation. if it is erected on bodies of water especially in the oceans to leverage on heavy wind generated by ocean currents; it is referred to as off-shore wind energy electricity generation. alta wind energy centre (awec) in tehachapi, california is currently the largest on-shore wind farm with operating capacity of , mw and the largest off-shore wind farm with generation capacity of mw is found in london array wind farm, uk [ ]. therefore, wind power potential cannot be underestimated in energy generation. . . biomass biomass is any organic material that has stored sunlight in the form of chemical energy; these include plants, american journal of electrical and electronic engineering agricultural crops or residues, municipal wastes and algae. it supplied far more renewable electricity than wind and solar power until recently [ ]. biomass resources of nigeria can be identified as wood, forage grasses and shrubs, animal waste and waste arising from forestry, agricultural, municipal and industrial activities, as well as, aquatic biomass [ ]. as state by achakpo, et al. ( ), biomass resources of the nation was estimated to be about x m.j. plant biomass can be utilized as fuel for small-scale industries. it can also be fermented by anaerobic bacteria to produce a very versatile and cheap fuel gas i.e. biogas. if developed properly, biomass can and should supply increasing amounts of “biopower”. the common way to harness biomass to biopower is to burn it to make heat. over the years, the technology for harvesting energy of biomass has developed into a more efficient and cleaner form (sustainable biopower). these technologies are direct combustion- burning the materials to produce steam which turns the turbine that produces electricity; co-firing- mixing it with coal and burn it at a power plant designed for coal or at natural gas-powered plants; repowering- coal plants running entirely on biomass; combined heat and power (chp); biomass gasification- heating biomass in an oxygen-controlled environment and under pressure, converts it into a mixture of hydrogen and carbon monoxide called syngas. this syngas is passed directly through turbine to generate electricity; and anaerobic digestion- micro organism breakdown of the biomass. many versions of efficient wood-burning and charcoal stoves have been developed and are being used in many parts of nigeria today with the overall objective of curtailing the amount of trees that are perennially cut to provide fuel wood and charcoal. biogas digesters, which are capable of producing biogas that could be used for domestic and industrial uses, have been developed in many parts of the country for sustainability. the energy from biomass will go a long way as an alternative source for power generation in nigeria if properly developed. . . geothermal energy geothermal energy is heat energy generated and stored in the earth; it is generated from the radioactivity decay and continual heat loss from the earth’s formation. the temperature difference between the planet and the surface drives a continuous conduction of thermal energy in form of heat from the core to the surface. rocks and water in the crust is sometimes heated up to oc as the temperature at the core – mantle boundary may reach up to oc. this energy can be used for district heating, space heating, industrial processes, desalination, agricultural applications and most importantly to generate electricity. the history of geothermal energy for electricity can be traced to when the world first commercial power plant was built. to generate electricity using geothermal energy, a hole is dug into the ground or rock to depths of about – km and water is allowed to flow into this hole and back to the surface. the water reaching the hotter earth crust is heated up and the steam travelling back up to the surface is used to drive turbines which in turn drive generators that produce electricity. using emerging technology known as enhanced geothermal systems (egs) the heat in the earth’s crust can be harnessed for electricity generation on a large scale. in , geothermal power installed capacity worldwide was up to , mw with united state currently leading with mw installed capacity and mw generating capacity [ ]. geothermal power is reliable and sustainable, as the earth’s internal heat content of joules is billon times current worldwide energy consumption. . . nuclear power nuclear power generation for commercial use started in at obninsk, russia when the first nuclear powered station; aps- was established and connected to the power grid [ ]. a nuclear power station is not much of a difference from fossil fuel-powered or steam-powered plants. the only difference is that the required heat energy to turn water to steam is generated in the nuclear reactor. it was discovered that certain isotopes of some elements can split and when this splitting occurs heat is generated. uranium - is one of such isotopes. during fission, uranium - atoms become unstable and split into two light atoms called fission products. the instability of these atoms causes the atoms to collide with other atoms resulting into chain of reactions. in the process, a lot of heat energy is generated. in nuclear power plants the heat is passed through water and the steam generated from the boiling water turns turbines and generates electricity [ ]. about t eu of uranium reserve has been discovered in two locations in nigeria by the defunct nigerian uranium mining company (numco) [ , , ]. this shows that nigeria has the potential for a self sustaining nuclear power plant. at gw, nuclear power amounts for % of total electrical power generation in the world. . . thermal energy thermal energy is the internal energy of a system due to the movement of particles by virtue of its temperature. thermal power stations make use of this principle to heat water into steam which turns a steam turbine to generate electricity. the steam is thereafter condensed and recycled. heat for steam production can be produced by burning coal, fuel oil or natural gas, nuclear reactors, geothermal and solar thermal. steam engines for electricity generation started in and since then, different power stations has been established using improved technology to generate electricity; an example is the mohave generating station near laughlin in nevada that is fuelled by coal with capacity of mw. . renewable energy potentials table . maximum possible power outcome per unit land or water area of renewable energy sources [ ] energy source power per unit land or water area on shore wind w/m offshore wind w/m solar pv panels - w/m geothermal . w/m rain water {highlands} . w/m hydroelectric facility w/m according to mackay ( ), the estimation of the various renewable energy sources can be carried out with reference to power per unit area of land or water. based on american journal of electrical and electronic engineering the methods and equations used by mackay ( ), the estimated power per unit area of various renewable energy sources is shown in table . . . wind farm for nigeria onshore wind potential: nigeria is one of the largest countries in africa by land mass which is about , square kilometers [ ]. the country only licensed “jbs wind power ltd” which has generation capacity of mw but it has no contribution yet into the national grid. the challenges in setting up a wind farm in nigeria ranges from lack of technical know-how, to government policy on renewable energy to little study on its energy potential among others. since wind is a natural phenomenon related to the movement of air masses caused primarily by the differential solar heating of the earth’s surface, therefore the seasonal variations in the energy received from the sun affects its strength and direction. in sambo ( ) study, wind energy potentials for a number of nigerian cities shows that the annual wind speed ranges from . m/s for port harcourt to a figure of . m/s for sokoto. the maximum extractable power per unit area, for the same two sites was estimated at . and . watts per square metre of blade area, respectively. and when the duration of wind speeds greater than m/s is considered than the energy per unit area works out as . and , . kwh per square metre of blade area for both cities respectively. improved wind turbines now have more generating capacity per square meter of blade. therefore, establishing ten ( ) wind farms each equipped with units of mw capacity wind turbines will give a cumulative of mw of power. considering also that one million homes in nigeria own a w wind turbine suitable for lighting and entertainment electronics, an additional mw of power could be included to the energy mix for the country. such projects can be funded by constituency development funds available to members of the house of representatives and senators in nigeria. offshore wind potential: the nigerian continental shelf is about , km [ ]. establishing two wind farms with units of mw wind turbines will give a cumulative of mw in total capacity with enough space for all marine activities. it should be noted that off shore wind power has higher potentials due to strong ocean currents. . . solar farm for nigeria the wind energy situation of the country has been researched into by the government and individual research bodies over time. the result of one of the studies is shown in figure . from the wind map, it can be concluded that nigeria indeed has the potential for huge wind energy development and will need to invest in this renewable source starting from the north, as wind speed is highest in the region including sokoto, jos, bauchi and kebbi states. mass-produced solar panels have at best efficiencies between – %. the efficiency means the capacity of the photovoltaic cell to convert the sun irradiance into electric power. solar energy resource is available in all parts of the country with an average sunshine hour of . kwh/m /day. the vast expanse of sahel savanna in the northern region of nigeria provides more than enough land space for this kind of project. according to mackay ( ), a yield of – w/m is estimated for solar power. assuming an area of about km and at % solar panel efficiency; ( ) ( ) the power achievable w / m x x m to w / m x x m mw mw is achievable. = = − this land space accounts for only about . % of nigeria’s total land mass. multiplying this land space by a factor of gives a geometric feasibility of up to mw of power. in addition, if one million homes in nigeria own a w solar power system on their rooftops, the cumulative power production will be mw of power which can add notably % to the present electricity consumption per capita. figure . nigeria wind map in m/s determined from year's measurements at m height, obtained from nigeria meteorological department, oshodi, lagos state, nigeria (nimet) [ ] american journal of electrical and electronic engineering . . small hydro power (shp) the jebba and kainji dams have capacities of mw and mw respectively while; the shiroro dam has a capacity of mw. these make the total existing capacity for hydro power in nigeria , mw. to complement the existing capacity, small and mini hydro power schemes with established potentials between kw to mw can be introduced around rivers and run off streams in nigeria [ ]. there are several dams around the country used for portable water supply which can further be exploited with small hydro turbines. given that % of nigeria land space is occupied by water [ ], and at w/m potential of hydro power, nigeria has a potential of generating , , mw of hydro power. i.e % x land mass x w / m . x , km x w / m , , mw. = = if only % of this is harnessed for large, small and mini hydro, a potential of , mw ( % of , , mw) can still be realized from hydropower in nigeria. this will give significant improvement over a survey of old states of the federation carried out in (i.e sokoto, katsina, niger, kaduna, borno, bauchi, gongola, plateau, benue and cross river), which showed that mw of shp can be harnessed from sites and another research by the federal ministry of power and steel in which showed , mw capacity hydro power sites exploitable in nigeria [ ]. . . geothermal power potential the potentials of geothermal power in nigeria are high but the required technology is in the developing stage globally. it requires drilling deep down into rocks and earth’s crust to gain access to the heat under the earth crust. offshore drilling is common in the exploration of crude oil or fossil fuel in nigeria’s oil rich niger delta region. geothermal power was after wide researches found to be cost effective, reliable, sustainable and environmentally friendly, but has historically been limited to areas near tectonic plate boundaries. studies have shown that a geothermal power farm is potentially viable in many cities of the country. from the records of the geothermal gradient, it shows that many sites in nigeria are good for geothermal system which is subject to confirmation with geophysical methods. as reported by avbovbo ( ), the normal geothermal gradient of the earth is between - °c/ m and geothermal gradient above this range is considered to be a good site for geothermal system. the geothermal gradient of niger delta region of nigeria ranges from . to . °c/ m. the geothermal gradient of anambra basin ranges from . to . °c / m [ ]. a similar study of the geothermal gradient of bida basin shows that it ranges from to . °c/ m. the borno basin temperature gradient ranges from . to . °c/ m. the study of sokoto basin has revealed its geothermal gradient to range from . to . °c/ m [ ]. the hot and warn springs is another indicator that shows the possibility of geothermal system in nigeria. the following areas have springs that indicate the leakage of geothermal system from the crust: akiri in benue state with a hot spring at about . °c, wikki in yankari game reserve, bauchi state has a warm spring of about °c and ruwan zafi in adamawa state located in lamurde generate a temperature of °c. these surveys show the feasibility of mw geothermal power in nigeria. . . biomass potential the country can utilize plant biomass as fuel for small- scale industries which could also be fermented by anaerobic bacteria to produce a cheap fuel gas (biogases). it is worth noting that, biogas production from municipal waste, agricultural residues and industrial does not compete for land, water and fertilizers with food crops like is the case with bioethanol and biodiesel production. this will also reduce the danger posed by these wastes. it has been estimated that nigeria produces about , tons of fresh animal waste daily. since kg of fresh animal waste produces about . m biogas, then nigeria can potentially produce about . million m of biogas every day from animal waste only. although biogas technology is not common in nigeria, various research works on the technology and policy aspects of biogas production has been carried by various scientists in the country. some significant research has been done on reactor design that would lead to process optimization in the development of anaerobic digesters [ ]. wood wastes and sawdust are other important biomass resources associated with the lumber industry. biomass utilization as energy resources is currently limited to thermal application as fuel for cooking and crop drying. there has been consensus in nigeria now that renewable energy can play tremendous role in the overall energy development of the nation. the views have been strengthened by the renewable energy master plan (remp) of the country as developed by the energy commission of nigeria (ecn), in conjunction with the united nations development programme (undp) in november [ ]. the objective among many is to accelerate the exploitation of renewable energy and development of the frame works for targets achievement. going by the potential of biomass, the remp has projected biomass to contribute mw of electricity in the medium term set at year and mw by . as reported by sambo ( ), significant research results have been achieved by relevant agencies in the public and private sector in biogas production, among which are the development of improved wood stoves and biomass briquetting technologies. this goes to show, a very high potential of biomass development for electricity generation in nigeria. . . nuclear power potential a mw nuclear power plant is estimated to consume ton of uranium in a year using the once- through type of nuclear reactors which burn up only the . % uranium- and discards the remaining uranium- as waste. recent development in technology now makes use of fast breeder reactors which converts the uranium- into fissionable plutonium and requires about ton of uranium/year to produce mw of nuclear power if well optimized. in the worst case scenario if uranium exploration is not feasible and nigeria needs to import from other countries. the cost of american journal of electrical and electronic engineering installing a fast breeder nuclear is high but the cost benefit ration makes it economical for power generation. considering the capacity of uranium deposits in nigeria , mw capacity nuclear power can be run sustainably in nigeria. . . thermal power potential currently about % of power generation in nigeria is thermal. the potential for thermal power is huge considering the abundance of fossil fuel and gases in nigeria. a , mw thermal plant being proposed will add significantly to the existing installations. in table , out of the power projects are thermal, but thermal power comes with high environmental pollution in the form of carbon footprint. hence this study discourages further construction of thermal stations in nigeria. . results the estimated energy from the renewable energy potentials that are feasible in nigeria is shown in table . going by this estimate, a total of , mw can be conveniently generated in the country which translates to about , kwhr/capita. going by figure , nigeria energy mix perspective will place the country close to the top highest electricity consumption per capita in the world. the analysis shows that small and large hydro power generation has the highest energy potential in nigeria. electrification rate- percentage of households with an electricity connection- in nigeria is estimated to be about % and kwhr/capita [ ], and from the cbn report of , the federal government has a projection of mw in order to achieve % electrification. it therefore means that, , mw energy capacity will achieve % electrification rate in nigeria but it is grossly inadequate to position the country as an industrialized nation. table . estimates of renewable energy potential in nigeria (mw) energy source power (mw) on shore wind offshore wind solar pv panels geothermal biomass small and large hydro , nuclear power , total , figure . pie chart of percentage estimates of renewable energy potential in nigeria figure . top electric power consumption (kwh per capita) in the world . conclusion this study has been used to address the issues of nigeria energy crises and suggested energy mix as solution. although nigeria is blessed with abundant energy resources with great potential for energy generation yet it’s still engrossed with high level of energy deficiency. this has invariably affected development and impinged negatively on the economic growth with some american journal of electrical and electronic engineering parts of the country, especially the rural areas, lacking access to modern resources which come with availability of electric power. there is a great prospect for power generation through the abundant renewable resources as describes in this study if the associated challenges hampering the technological advancement are surmounted. currently, hydro power which contributes about % of power generation in nigeria is the only renewable energy source of power and its potential is yet to be fully exploited. small hydro power can be coupled with several existing potable water supply schemes in the country at low cost in addition to the power supply from large hydro power schemes of the nation. nuclear power plant is another area with great potential for high capacity power generation (about . %) if properly harnessed. the inclination towards gas-fired thermal plants will only create more environmental problems by depleting the ozone layer through the emission of co gases, it is therefore not considered as a prospect. the estimated result put solar energy as the third highest energy harvest potential in nigeria. these analyses clearly show the potentials of managing the country’s natural resources to cater for its growing energy demand and consequently its economic development. the estimates are feasible and the economic involved in executing the projects is highly objective. references [ ] onec department report, . 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(eds.)), pp. - , joja educ. research and pub. ltd. international journal of soft computing and engineering international journal of recent technology and engineering (ijrte) issn: - , volume- issue- s, october published by: blue eyes intelligence engineering & sciences publication retrieval number: c s / ©beiesp doi: . /ijrte.c . s  abstract: southeast asia country are mostly classified as developing country. one of the aspects that asean concern is the energy poverty problem. based on the statistics known, around million people in the sea facing lack of access of electricity. besides that, million people highly depending traditional biomass to fulfil their daily needs. myanmar is one of the sixth poorest country in the sea. the access of electricity in myanmar are low and experience slow improvement over a decade. energy policy had been drafted and implemented by myanmar government. however, the result is no significant. this paper aims to analyze the social economic impact on the energy consumption of myanmar. the aspect of analyze include energy use, foreign direct investment, population growth, industry value added, gdp per capita growth and trade. multivariate analysis method adopts which includes descriptive statistics analysis, unit root test, johannsen cointegration analysis, vector error correction model and granger causality test. the result shows unidirectional granger causality for energy consumption with all the aspects. analyzed data play important role in the future policy planning. policies such as renewable energy policy, reducing energy prices, taxes and subsidies can help in increasing energy consumption which will bring up other social economic. index terms: energy policy; energy poverty; granger causality. i. introduction southeast asia (sea) is the part of asia which covert up . % of the world population. sea country consists of brunei, cambodia, east timor, indonesia, laos, malaysia, myanmar, philippines, singapore, thailand and vietnam [ ]. most of the sea country is developing country whereby an organization has been established to seek for cooperation among member to achieve improvement. association of southeast asian nations (asean) been established since and till now all sea country participating expect east revised manuscript received on august , sim sy yi, faculty of engineering technology, universiti tun hussien onn malaysia, parit raja, batu pahat, johor. goh hui hwang, faculty of electrical & electronic engineering, universiti tun hussien onn malaysia, parit raja, batu pahat, johor. ili najaa aimi binti mohd nordin, faculty of engineering technology, universiti tun hussien onn malaysia, parit raja, batu pahat, johor. ling chin wan, faculty of electrical & electronic engineering, universiti tun hussien onn malaysia, parit raja, batu pahat, johor. goh kai chen, faculty of technology management & business, universiti tun hussein onn malaysia, parit raja, batu pahat, johor, malaysia. sim ga yi, faculty of electrical & electronic engineering, universiti tun hussien onn malaysia, parit raja, batu pahat, johor. timor [ ]. one of the aspects that asean concern is the energy poverty problem [ , ]. based on the statistics known, around million people in the sea facing lack of access of electricity. besides that, million people are still depending traditional biomass to fulfil their daily needs [international energy agency. southeast asia outlook ]. in the year , asean energy market integration (aemi) had been launched to overcome the problem of energy poverty in the region. overall for the aemi key element is enhancing the modern and clean energy accessibility and targeting several main factors which may become the catalyst to achieve the goal [ - ]. energy poverty is not only happening in the sea. the energy poverty also leads to a low living standard where they cannot cope up with other developed countries in all aspect. one of the obvious indicators is social economic. social economic is refer to the relationship of social behavior with economics. hence, both factors can affect one another. improving the social economic enable to achieve a better standard of the living environment [ , ]. however, the improvement had caused a certain degree of negative effect on the environment. apparently, energy plays important role in developing the social economics of certain province or country. in another word, energy consumption is one of the major indicators of the social economic development level [ , ]. one of the supportive evidences for this statement is the energy crisis in the year [ ]. back in , energy crisis resultant of the crucial oil price. the fluctuation of oil price is catastrophic for the people where living expenses increased tremendously especially for the developing country. developing country hardly conclude energy requirement for the nation which resultant deeply affected by the energy crisis. the energy crisis had shown the importance of energy preservation and management process [ , ]. along with the awareness on the environment, renewable energy is widely exploded. among all the renewable sources, biomass and fuelwood are the most promises and consistent resources in any nation. in conjunction on the increase of demand due to population, renewable energy became the most promising solution for resolving energy poverty. renewable energy also part of the electrical planning for a rural area which hardly covers by the existing power grid. examination of social economic impact on the energy consumption of myanmar sim sy yi, goh hui hwang, ili najaa aimi binti mohd nordin, ling chin wan, goh kai chen, sim ga yi examination of social economic impact on the energy consumption of myanmar published by: blue eyes intelligence engineering & sciences publication retrieval number: c s / ©beiesp doi: . /ijrte.c . s ii. energy policy of myanmar myanmar is one of the sixth poorest country in the sea. the access of electricity in myanmar are low and experience slow improvement over a decade. even major citizens are frequently experiencing blackout which shows the urgent on resolving energy poverty problem in myanmar [ , ]. the energy consumption data of myanmar show an increasing trend but seem cannot cope with the increase of population. lack of electricity access reduces the usage of technology in the society which leads to a low developing nation. only % of the population in rural area gain access of electricity [ ]. in local, myanmar citizen utilizes traditional biomass more than electricity [ ]. the use of traditional biomass involving a lot of side effect. combustion of plywood for cooking causing the cooker inhale fine particle that produced [ ]. myanmar government currently putting high effort on investigating the possibilities on the renewable energy to the country development [ ]. the initial plan of attracting foreign investment on increasing coal-fired power plants to increase the energy production. however, the plan seems to be no widely accepted by the community due to the environmental concern. the focus is changing into hydropower [ ]. as the concern toward the rural area, the local facilities are basic and traditionalize. technology improvement had yet benefit to those who stay at rural area. industrial still operate under traditional method due to lack to technologies expose. in long-term, problem such cannot fulfil demand may happen. iii. literature analysis numerous studies upon social economy development had been conducted. an empirical survey for greece for the social economy determinants of energy consumption had been done [ ]. the research uses energy consumption as the dependent variable which concludes the granger causality relation to the other variables. the study outcome shows a long-term relationship between energy consumption with other variables is statically significant. causality test showed bidirectional relationship between energy consumption and economic growth. cointegration study cointegration study on five of the asean country by multivariate cointegration analysis [ ]. the five countries are indonesia, malaysia, philippines, singapore and thailand. the study focusing on the cointegration between energy consumption with the carbon dioxide emission. the cointegration test method adopted by the study is autoregressive distributed lag method. this result shows statically significant for energy consumption and carbon dioxide emission relationship in both short and long run. the author provides clear view on the asean country with different economic level react upon the issue if energy consumption effect on the carbon dioxide emission or in another word means the environment. john asafu-adjaye [ ] investigate cointegration among energy consumption, energy prices and economic growth. the investigated country are india, indonesia, thailand and philippines. johansen cointegration test and granger causality been used to validating causality between energy consumption and income of the four asian developing countries. long run and short run result also been concluded as beneficial to the policy planning and forecasters. for the study, most of the literature adopt time series analysis method to find the cointegration relation between variables. myanmar is one of the countries where least analysis was done which belief due to the lack of raw data. iv. data and methodology the data presented in this paper is adopted form world development indicator ( ). the time series data use ranging from to which is years data. data adopted are energy use, foreign direct investment, gross domestic product per capita growth, industry value added, population growth and trade. the proposed energy consumption function for myanmar is shown as a mathematical model as below. the overall study is to identify the effect of the variables to one another.   , , , , ec f fdi pop indus gdp trd      ( ) ec= energy use (kg of oil equivalent per capita) fdi = foreign direct investment, net (bop, current us$) pop= population growth (annual %) indus = industry, value added (annual % growth) gdp = gdp per capita growth (annual %) trd = trade (% of gdp) this study adopts multivariate analysis method. the method includes univariate, bivariate and multivariate analysis to achieve the objective. the statistical method used is descriptive statistics analysis, unit root test, johannsen cointegration analysis, vector error correction model and granger causality test. analyses form the time series data, unit root test applies to test the stationaries properties. two approaches of unit root test are used that is augmented dickey-fuller test and phillips-peron test. this test is preliminary and crucial where it may affect overall analysis result. johannsen cointegration analysis is used to identify the existing of the cointegration relationship between the variables. the method is to perform an estimation upon the value at risk object in a group to value. form this method, adjustment parameter value can be identified which is the need in preform vector error correction method. this test can proceed in condition at least one cointegration relation was found. vector error correction method applies to identify the effect on each variable involves towards the independent variable. this method enables on to quantify the effect of variables. v. result and discussion table shows the descriptive statistics for myanmar. the understanding of actual value deviation from mean is important analysis data in the findings. for energy consumption and foreign direct investment, the standard deviation is . and . respectively. as for gross domestic product growth rate, industrialization grow rate, population growth rate and trade (gdp%) are . , . , . and . respectively. international journal of recent technology and engineering (ijrte) issn: - , volume- issue- s, october published by: blue eyes intelligence engineering & sciences publication retrieval number: c s / ©beiesp doi: . /ijrte.c . s table i. descriptive statistics for myanmar variables mean median maximum minimum std. dev. skewness kurtosis ec . . . . . . . fdi . . . . . - . . gdp . . . . . - . . indus . . . . . - . . pop - . - . - . - . . - . . trd . - . . - . . . . table shows the correlation test result under pearson correlation method. from the result, energy consumption shows a statistically significant relationship with all variables. for gross domestic product growth and industrialization growth rate, energy consumption shows negative relationship but insignificant. for industrialization grow, significant positive show for gross domestic product grow while other variables are negative insignificant statistically. foreign direct investment has a negative significant relationship with industrialization grow and gross domestic product. even though foreign direct investment has a positive relationship with energy consumption, but the relationship is insignificant. table ii. correlation test (pearson correlation) ec fdi gdp indus pop trd ec fdi . gdp - . - . indus - . - . . pop . . - . - . trd . . - . - . . unit root test is tested to avoid unreliable result or invalid result for the future cointegration analysis. the unit root test adopt for the analysis is augmented dickey-fuller test and phillips-perron test is added to further testify the result. for a tie series data analysis, if the series found to be stationary, it means the series has a unit root. table shows the augmented dickey-fuller (adf) test with the trend and without trend. as for the result, if the t-statistic over then the critical value can conclude that the hypothesis is been rejected. for the test only intercept, all variable has no unit root at the level. however, test for intercept and trend shows all variable stationary at level except trade grow. hence, overall can be concluded that all variable will be stationary at level . table iii. augmented dickey-fuller unit root test variable intercept intercept and trend t-statistic critical t-statistic critical value value ec - . - . . - . fdi - . - . - . - . gdp - . - . - . - . indus - . - . - . - . pop - . - . - . - . trd . - . - . [ ] - . [ ] table shows the johansen cointegration test for the variables. from the result, proving that there is cointegration in between the variables. the result judge by if trace statistic is greater than the critical value, the null hypothesis can be rejected. the result also can be evaluated based on eigenvalue where if the value is more then . , the null hypothesis can be rejected. this test shows the possible on co-relationship between the variables. since at least one cointegration relationship was found, this means that socio-economic factor has an alpha significant long-term impact on energy consumption. table iv. phillips-perron unit root test hypothesize d no. of ce(s) eigenvalu e trace statistic critical value ( . ) prob.* * none * . . . at most * . . . . at most . . . . at most . . . . at most . . . . at most . . . . vector error correction modal (vecm) method use due to the existence of cointegration found in johansen cointegration test. however, the focus of this work is on the energy consumption where the result of vecm of energy consumption will be discussed further. the result shows high r-squared value . which means there is no serial correlation for the selected variables. table shows the energy consumption of vector error correction estimation. energy consumption is the independent variable which is the focus of this work. the result shows statistical significance in the long run causality for both lags except examination of social economic impact on the energy consumption of myanmar published by: blue eyes intelligence engineering & sciences publication retrieval number: c s / ©beiesp doi: . /ijrte.c . s for gdp lag . table shows the granger causality test. this test is to confirm the relationship impact between the variables. from the result, it shows that foreign direct investment, gross domestic product, trade and population have granger cause energy consumption. this means the four variables have only unidirectional relationship with the energy consumption. table v. johansen cointegration test dependent variable: d(ec) method: least squares (gauss-newton / marquardt steps) date: / / time: : sample (adjusted): q q included observations: after adjustments d(ec) = c( )*( ec(- ) + . *fdi(- ) - . *gdp( - ) + . *indus(- ) + . *pop(- ) - . *trd(- ) - . ) + c( )*d(ec(- )) + c( ) *d(ec(- )) + c( )*d(fdi(- )) + c( )*d(fdi(- )) + c( )*d(gdp(- )) + c( )*d(gdp(- )) + c( )*d(indus(- )) + c( )*d(indus(- )) + c( ) *d(pop(- )) + c( )*d(pop(- )) + c( )*d(trd(- )) + c( )*d(trd( - )) + c( ) coefficient std. error t-statistic prob. c( ) - . . - . . c( ) . . . . c( ) . . . . c( ) . . . . c( ) . . . . c( ) . . . . c( ) - . . - . . c( ) . . . . c( ) - . . - . . c( ) - . . - . . c( ) . . . . c( ) - . . - . . c( ) . . . . c( ) . . . . r-squared . mean dependent var . adjusted r-squared . s.d. dependent var . s.e. of regression . akaike info criterion - . sum squared resid . schwarz criterion - . log likelihood . hannan-quinn criter. - . f-statistic . durbin-watson stat . prob(f-statistic) . international journal of recent technology and engineering (ijrte) issn: - , volume- issue- s, october published by: blue eyes intelligence engineering & sciences publication retrieval number: c s / ©beiesp doi: . /ijrte.c . s table vi. vecm of energy consumption null hypothesis: obs f-statistic prob. fdi does not granger cause ec . . ec does not granger cause fdi . . gdp does not granger cause ec . . ec does not granger cause gdp . . indus does not granger cause ec . . ec does not granger cause indus . . pop does not granger cause ec . . ec does not granger cause pop . . trd does not granger cause ec . . ec does not granger cause trd . . gdp does not granger cause fdi . . fdi does not granger cause gdp . . indus does not granger cause fdi . . fdi does not granger cause indus . . pop does not granger cause fdi . . fdi does not granger cause pop . . trd does not granger cause fdi . . fdi does not granger cause trd . . indus does not granger cause gdp . . gdp does not granger cause indus . . pop does not granger cause gdp . . gdp does not granger cause pop . . trd does not granger cause gdp . .e- gdp does not granger cause trd . .e- pop does not granger cause indus . . indus does not granger cause pop . . trd does not granger cause indus . . indus does not granger cause trd . . trd does not granger cause pop . . pop does not granger cause trd . . vi. conclusion the study examines the cointegration between energy consumption with the social economy. social economy variables included is foreign direct investment, gross domestic product per capita growth, industry value added, population growth and trade. besides that, the case study only refers to myanmar. the result showed positive statistically significant on the cointegration analysis. unit root test with adf and pp clearly test the stationary of the variables. the johansen cointegration test show at least one cointegration exist which further the analysis by vecm. lastly, granger causality test concludes the direction of granger causality for each variable towards one another. the study finding shown unidirectional granger causality for energy consumption with foreign direct investment, gross domestic product, trade and population. this information beneficial in contribute idea for policy analysis and forecaster. high energy consumption will lead to the increase of foreign direct investment, gross domestic product, trade and population growth. policy such as renewable energy policy, reducing energy prices, taxes and subsidies can help in increasing energy analysis of social economic impact on the energy consumption of myanmar published by: blue eyes intelligence engineering & sciences publication retrieval number: c s / ©beiesp doi: . /ijrte.c . s consumption which will bring up other social economic. besides that, the finding of single-equation regression provides foundation for forecaster on econometric forecasting. acknowledgment the authors would like to thank the ministry of science, technology and innovation, malaysia (mosti), and the office for research, innovation, commercialization, consultancy management (oricc), universiti tun hussein onn malaysia (uthm) for financially supporting this research under the science fund grant no.s and igsp vot. u . references . worldmeter. available from: http://www.worldometers.info/world-population/south-eastern-asia-popu lation/. . irvine, r., the formative years of asean: – , in understanding asean. , springer. p. - 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( ): p. - . authors profile sim sy yi received the b.eng degree in electrical engineering and ph.d degree in electrical from universiti tun hussein onn malaysia (uthm) in and , respectively. currently, she is a lecturer in universiti tun hussein onn malaysia (uthm). her current research interests include of power electronic, artificial intelligent, renewable energy and power system. goh hui hwang received his b.eng degree in electrical engineering and m.eng degree in electrical from universiti teknology malaysia (utm) in and , respectively. then he received his ph.d degree in universiti teknologi malaysia (utm) in . currently, he is an associate professor in universiti tun hussein onn malaysia (uthm). his current research interests include of power system, artificial intelligent, renewable energy and renewable energy policies. ili najaa aimi binti mohd nordin received his b.sc. in electrical engineering (medical) from universiti teknologi malaysia in and graduated in same university with a phd in electrical engineering in . ling chin wan received the b.eng degree in electrical engineering and m. eng degree in electrical from universiti tun hussein onn malaysia (uthm) in and , respectively. currently, he is pursuing the ph.d. degree at the department of electrical and electronic engineering, universiti tun hussein onn malaysia (uthm). his current research interests include of power electronic, renewable energy, artificial intelligent and renewable energy policies. goh kai chen received the b.eng degree in science and m.eng degree in science (construction management) from universiti teknology malaysia (utm) in and , respectively. then he received his ph.d degree in queensland university of technology in . currently, he is an associate professor in universiti tun hussein onn malaysia (uthm). his current research interests include of environment sustainable construction. sim ga yi received his b.eng. (electrical engineering) from universiti tun hussien onn malaysia (uthm) in . she is currently pursuit master in universiti tun hussien onn malaysia. oil-column calculations in stratigraphic traps: abstract; geothermal power in the southwest: abstract; recent and ancient turbidites and contourites: abstract association round table slope in the alaminos canyon area, gulf of mexico, indicate sand input from the ancestral colorado-brazos and mississippi river systems. the clay minerals in the area were derived from indeterminate sources and were incorporated in coarse samples through resuspension of former sediment. vermiculite, as well as tubular hallaysite, were identified in clay samples. the first mineral is unreported in the northwest gulf and the latter is only known from the mississippi delta in the northwest gulf area. the "hummocky" nature of the bathymetry in the area re- sulted from salt diapirism and scouring by tractive and/or density flow. sand-size sediment was transported to the area from river systems by longshore drift during the holocene transgression or through channels still identifiable on the pres- ent continental shelf the lineation of one of these features, the outer colorado-brazos channel, is probably due to salt tecton- ics and not the result of a barrier spit as previously reported. berg, r. r., dept. geology, texas a&m univ., college station, tex. oil-column calculations in stratigraphic traps oil columns can be calculated for simple stratigraphic traps if the rock and fluid properties are known or can be estimated. because oil migration is prevented by capillary pressure in small pores of the trap fades, direct measurements of capillary pressure allow oil columns to be calculated, but such measure- ments are rare. an alternative is to determine pore size from porosity and permeability data using an empirical equation, and then to compute the capillary pressure by an estimate of fluid properties. an example of oil-column calculation is from the milbur field, burleson county, texas, a lower wilcox stratigraphic trap. using core analysis from a nearby well, an oil column of - ft would be expected for the trap, and this estimate agrees reasonably well with an actual oil column of - ft for the field. the most important part of such calculations is the real- ization that the trapping facies itself can have significant poros- ity and permeability and yet form an effective barrier to oil migration. the result is that the best reservoir may occur down- dip from dry holes with porous water-bearing sandstone and oil shows, rather than updip at the pinchout. birdseye, h. s., consultant, albuquerque, n.m. geothermal power in the southwest in this era of great concern over the environment and the energy crisis, much attention is being directed toward geother- mal power as a partial panacea for both predicaments. of approximately , known geothermal occurrences in the uaited states, most of which are in and west of the rockies, a relatively small percentage are classified as dry steam reservoirs, capable of producing hot unsaturated steam which poses mini- mal efiluent disposal problems. others, such as the salton sea field in southern california, pose critical waste brine difficulties, which will probably be solved only by reinjection. a major geothermal field, e.g., the geysers in northern california, is expected to produce steam adequate to generate from , to , megawatts of electricity, with -year gross revenue from steam sales on the order of $ billion. there are known geothermal occurrences in the southwestern states of texas (less than a dozen). new mexico ( ), arizona ( ), nevada ( ), and southern california (about ). it is likely that additional geothermal prospects will be developed by the use of sophisticated geologic mapping, coupled with such geophysical methods as studies of temperature-gradients, mi- croseisnris and ground noises, resistivity, and remote sensing, and chemical methodology useful in determining maximum water temperature in the system and the age of that water. bouma, a. h., dept. oceanography, texas a&m university, college station, tex. recent and ancient turbidites and contourites fossil turbidites have been recognized and described from many areas all over the world. a turbidite model, comprised of a fixed succession of sedimentary structures, was established a decade ago and seems to be usable, although some changes have been suggested. turbidites are generally assumed to be deposited by turbidity currents, but the presence of these currents in the marine realm has not been definitely established. submarine canyons presum- ably are the major, if not only, important transport route for moving "shallow" water material to "deeper" basins. questions arise about the origin of turbidity currents when studying can- yons in which gradual filling followed by sudden emptying has occurred. the material in the canyon head moves downward slowly, comparable to glaciers. besides this slow sliding, trac- tion currents and debris flow have been suggested. where tur- bidity currents start, and if they absorb the slow moving can- yon fill, are questions that cannot be answered yet. other prob- lems are the relation between fluxoturbidites, or gravities, and turbidites, and the use of the terms "proximal" and "distal" turbidites. in comparing recent turbidites with ancient ones, many dis- crepancies appear, most of which can be euminated by consid- ering the influence of primary consolidation on segmentary structures. studies indicate that the use of electrical logging and seismic records do not allow detailed interpretation of deposits such as turbidites. the resolution of the records is not fine enough, although their application for basin analyses and overall trends is necessary. recently a new genetic term, "contourites," was introduced for sediments redeposited by contour currents. recent and ancient contourites are compared with turbidites and only mi- nor differences exist. a combination of parameters may allow a distinction between the two types and it is possible that both can be found in the same area. brown, l. f., jr., bur. econ. geology, univ. texas at aus- tin, austin, tex. south texas eolian system—model of coastal eolian processes few oil and gas reservoirs have been interpreted as sands deposited within eolian depositional systems. eolian facies may, however, be more common in ancient basins than heretofore recognized. continued documentation of holocene eolian sys- tems, such as the south texas system, provides a model for reevaluating the genesis of numerous unfossihferous, well- sorted blanket sand bodies, many of which are associated with ancient, paralic depositional systems. pleistocene paralic depositional systems along the south texas coast dictate the natiu'e and distribution of facies pat- terns, environments, and processes exhibited by the overlying holocene south texas eolian system. a dominant southeast wind, high summer temperatures, and high rainfall deficiency combine with an abundant supply of pleistocene sand to pro- vide the proper framework widiin which extensive eolian defla- tion and dune migration can occur. eolian lobes are supplied with sand from pleistocene barrier- strandplain facies and fluvial meanderbelt deposits. loess sheets are derived from distant lobes, as well as from deflation of local pleistocene deltaic and fluvial facies. deflation of thick pleistocene fluvial-deltaic sand facies is commonly stabilized when erosion reaches the shallow groundwater table. maximum deflation occurs on the upwind, coastward margin of the sys- tem, especially where only thin pleistocene paralic sands are available to supply dune trains; mud deflated by strong off- microsoft word - whitepaper_final_horowitz.doc a law enforcement perspective of electricity deregulation ira horowitz* warrington college of business, university of florida, gainesville, fl - , usa abstract in april , the california attorney general’s (ag) office issued a white paper that provided a “law enforcement perspective of the california energy crisis.” to complete this special issue's coverage, i summarize three aspects of that paper: notably, the deficiencies in market oversight and enforcement that left the deregulated market prone to potential abuse, the principal modus operandi that some market agents used to exploit those deficiencies without fear of retribution, and the ag’s “recommendations for improving enforcement and protecting consumers in deregulated energy markets.” * tel: + - - - ; fax: + - - - email address: ira.horowitz@cba.ufl.edu . introduction in , the california legislature enacted assembly bill (ab) under which retail electricity rates would remain subject to regulatory review by the california public utilities commission (cpuc), at least for the foreseeable future, with wholesale rates being determined by market forces [ - ]. to that end, california’s three major investor- owned integrated utilities (ious) were encouraged to divest themselves of their fossil fuel generating plants. the ious turned over control of their transmission lines to an independent system operator (iso) that would be subject to regulatory oversight by the united states federal energy regulatory commission (ferc). the iso was charged with managing the grid’s day-to-day operations, which means allocating limited network capacity, and purchasing and selling reserves and real-time energy so as to correct any minor real-time imbalances between loads and resources. separately, ab also created a wholesale spot market in which the ious must transact. established in , the california power exchange (px) served as the central market for some % of the state’s energy transactions, with the market-clearing prices determined by locational demands and supplies. the feel-good presumption behind all of this was that consumers would reap the benefits of partial deregulation and competitive spot markets. the reality of may through june , however, was an energy crisis that manifested itself in soaring wholesale electricity prices far above the capped retail rates, frequent power shortages and consequent rolling blackouts. during november through may , the coincident dramatic price increases in natural gas exacerbated the electricity problems. the px closed its doors on february , , and the responsibility to ensure competitive electricity prices for transactions other than the bilateral power agreements between ldcs and energy suppliers fell to the iso. nevertheless, the soaring wholesale prices and capped retail rates caused financial insolvency of two of the ious: pacific gas and electric company and southern california edison. san diego gas and electric was spared because of the removal of capped retail rates in mid- upon its full stranded- cost recovery. it was apparent that deregulation wasn’t working as the california legislature had intended and that something was seriously amiss. it didn’t take too long before academics and practitioners alike were offering their explanations and solutions, and for enron to become a household word - and not just in the united states. one problem in particular was that the ious could only transact in spot markets, which might tempt both large- capacity generators to withhold power when supply was tight so as to drive up the wholesale price on a virtually inelastic demand curve, and greedy marketers to devise and implement various short-term market-gaming strategies to pad their pocketbooks, to the ultimate detriment of consumers for whom adequate remedies are unavailable. in april , the california attorney general’s office (ag) entered the debate through a “white paper” [ ] that provided a “law enforcement perspective of the california energy crisis” that plagued california’s electricity and natural-gas markets. at the request of this journal's editor-in-chief, i summarize three aspects of that paper: notably, the deficiencies in market oversight and enforcement that left the deregulated market prone to potential abuse, the principal modus operandi that some market agents used to exploit those deficiencies without fear of retribution, and the ag’s “recommendations for improving enforcement and protecting consumers in deregulated energy markets.” . the deficiencies the ag identifies and details what boil down to five major failures and deficiencies in market oversight and enforcement. first, it is left to ferc to determine whether a given generator possesses sufficient market power as to adversely impact price should it choose to do so, say by withholding supply. once ferc has made a determination that a generator does not possess the requisite power, the generator is free to charge whatever prices buyers are willing to pay, and, ferc insists, the generator is immunized from retroactive refunds and antitrust actions. ferc, however, has limited expertise in antitrust and market-power issues, and has not necessarily devoted the time and effort required to make appropriate determinations in those regards. second, although electricity sellers are required to provide ferc with quarterly reports of their business transactions so that it can adequately monitor the energy markets and ensure market-based rates that would approach the competitive norms, the requirement was all too often honored in the breach. by viewing the lapses as “essentially a compliance issue” that an offending generator could rectify by filing an amending report, ferc failed to detect a plethora of instances in which participants manipulated the markets. third, generators and traders believe their pricing practices are not subject to judicial review, under the filed-rate doctrine that prevents legal challenges to filed rates that have been approved by administrative agencies such as ferc. believing that the process of reviewing all rates and terms of sale impeded the competitive process, because it kept sellers from reacting promptly to changing market conditions, ferc in the late s “drastically cut back the filing requirements for sellers transacting at market-based rates.” once a seller demonstrates that it lacks market power or has taken steps to mitigate any power that it might possess, it need only file a “market-based tariff” stating that rates will be determined by agreement of the transacting parties, and it is this tariff to which the filed-rate applies and that earns ferc’s blanket authorization. fourth, the iso, the cpuc, and the electricity oversight board (eob) also failed to exercise adequate market oversight and enforcement of state laws that are themselves of limited enforceability. finally, the security and exchange commission (sec) exempted the ious from full scrutiny under the public utilities holding company act (puhca). pacific gas & electric (pg&e), in particular, took advantage of the situation by diverting $ billion in earnings to its parent company in the face of large losses and impending bankruptcy. . exploiting the deficiencies the ag focuses on two very different ways in which the market-oversight-and- enforcement deficiencies were exploited: ( ) the raw exercise of undetected and/or undisciplined market power by merchant generators that have no franchised service territories and no legal obligation to serve retail customers; and ( ) traders gaming the market through highly complex strategies that are difficult to detect, regulate, or subject to judicial review and consequences.. in the former regard, generators withheld power from california’s markets by both reducing production for those markets and simultaneously exporting power to neighboring states, and then allowing the law of supply and demand to take effect – as it did and with predictable consequences. in the latter regard, enron in particular devised a series of marketing-gaming strategies, four of which take center stage in the ag’s report: falsely scheduling power along a congested transmission line in the expectation of being paid to reduce the load; exporting power to a willing accomplice that would resell that power for import at a much higher price; submitting “paper” offers to the iso in the day-ahead market and covering those offers at the lower capped prices of the real-time market; and scheduling energy in the opposite direction of congestion and then being paid to reduce a load that it had no intention to provide in the first place. . the key recommendations the ag makes four key recommendations, among others, to correct the deficiencies. first and foremost, there should be a codified statement to the effect that the filed- rate doctrine does not apply to market-based rates and that retroactive refunds, if justified, are available to consumers. further, and with specific regard to ferc, there should be established “written criteria for market monitoring, identification of gaming, and steps to be taken when markets fail to function properly” and a mechanism should be created “to encourage direct consumer participation” in proceedings before it. second, provide the iso with a “specific and transparent market monitoring system, with specific and enforceable standards for addressing market anomalies and abuses of market power,” along with the resources and administrative enforcement authority that would allow it to be an effective enforcer and market monitor. third, amend federal law to require ferc to cooperate with state and local investigations of any alleged misconduct in the energy markets, and to promote coordination of federal and state enforcement efforts; and consider creating a multi- jurisdictional interagency energy task force. fourth, eliminate the intrastate exemption of interstate utility holding companies from the puhca, and if the puhca is amended or rescinded, retain the oversight-and- review aspects of the law for such holding companies. . conclusion the notion of deregulated energy markets that are subject only to the discipline of competitive market forces is assuredly appealing, even though the california experience makes evident that it is somewhat naïve. the ag’s white paper argues that because such markets are particularly susceptible to market-power abuses as well as obtuse gaming strategies by unscrupulous agents, a critical aspect of the deregulation process should contain the following components: (a) the concurrent establishment of cooperating oversight bodies that have been provided with well-defined responsibilities; (b) the appropriate criteria and analytic frameworks for gauging market performance; (c) the resources to carry out their missions; and (d) the power to enforce their findings. the ultimate end is that the oversight bodies must protect consumers who are compensated for any losses that they may have suffered as the result of non-competitive acts. it is a well taken argument. reference [ ] jurewitz jl. california electricity debacle: a guided tour. electricity journal ; ( ): - . [ ] woo ck. what went wrong in california’s electricity market? energy ; ( ): - . [ ] woo ck, lloyd d, tishler a. electricity market reform failures: uk, norway, alberta and california. energy policy ; ( ): - . [ ] california attorney general’s office. attorney general’s energy white paper. sacramento, ca, . see also: http://caag.state.ca.us/publications/energywhitepaper.pdf. regional development and oil strategy: the case of algeria econstor make your publications visible. a service of zbw leibniz-informationszentrum wirtschaft leibniz information centre for economics schliephake, konrad article — digitized version regional development and oil strategy: the case of algeria intereconomics suggested citation: schliephake, konrad ( ) : regional development and oil strategy: the case of algeria, intereconomics, issn - , verlag weltarchiv, hamburg, vol. , iss. , pp. - , http://dx.doi.org/ . /bf this version is available at: http://hdl.handle.net/ / standard-nutzungsbedingungen: die dokumente auf econstor dürfen zu eigenen wissenschaftlichen zwecken und zum privatgebrauch gespeichert und kopiert werden. sie dürfen die dokumente nicht für öffentliche oder kommerzielle zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. sofern die verfasser die dokumente unter open-content-lizenzen (insbesondere cc-lizenzen) zur verfügung gestellt haben sollten, gelten abweichend von diesen nutzungsbedingungen die in der dort genannten lizenz gewährten nutzungsrechte. terms of use: documents in econstor may be saved and copied for your personal and scholarly purposes. you are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public. if the documents have been made available under an open content licence (especially creative commons licences), you may exercise further usage rights as specified in the indicated licence. www.econstor.eu forum oil strategies and development the authors of the following articles deal with the special problems facing two groups of oil ex- porting countries and their implications for the domestic and external economic strategy of these countries. a. alkazaz presents the case for the arab states which are encountering difficulties in using their large oil revenues in their own countries owing to personal and material shortcomings of their infrastructure, while k. schliephake shows by the example of algeria what contribution the oil can make to the regional development of countries with large populations and favourable objective conditions for speedy industrialization. regional development and oil strategy" the case of algeria by dr konrad schliephake, hamburg * u ntil the much talked-about "energy crisis" struck the world in the autumn of -- the flare-up of the palestine conflict was only the spark which set it off - analyses of the national and international oil and energy policies focused on the mechanics of the inter- national markets. there had been only a few case studies in which it had been pointed out that the mineral oil industry in its traditional form [ ] lacked integration with the other sectors of the economy; [ ] was by the logic of its system prevented from making a pur- posive contribution to regional economic and social develop- ment; and [ ] under the prevailing systems and economic principles made only a small contribution to the advancement of the oil produc- ing countries: hence there was � german institute for african studies. of. p. m a r t h e l o t , la r~volution du p~trole dans un pays insuffisamment d~ve- iopp~: la libye (the oil revolution in a n underdeveloped country: libya), in: ca- hlers d'outre-mer, bordeaux, no. i , , pp. - . a need for integral planning to use the oil in the interests of the producing countries - otherwise a major crisis was bound to occur at some time or other. a shift in control the oil producing countries have in the meantime gained an increasing measure of control over their raw material and brought about a shift in the centres of economic policy decisions in their favour. as a result of this the political options impinging on the world market through the relatively solid producers' cartel of the opec are attaining growing impor- tance as the basis of new national energy and raw material policies on the part of individual producing countries. what is the basis of these political options and what will be their effects in the future has been examined in field studies for which algeria served as a representative example. with the interrelations be- tween population, crude oil out- put and available infrastructure as the criterion, the oil produc- ing countries may be roughly divided into the following groups: [ ] producing countries with a high per-capita income (saudi arabia, kuwait, qatar, abu dhabi, libya): their financial resources are increasing rapidly, but infrastructural shortcomings of a personal and material nature and lack of a nation-wide market make it difficult to estab- lish industries. [ ] producing countries with average per-capita incomes (algeria, iraq, iran, venezuela, ecuador): they appear to offer the best conditions for quick industrial development. they possess an infrastructure ca- for details see the author's monograph: erdsl und regionale entwicklung - bei- spiete aus algerien und tunesien (mineral oil and regional development -- examples from algeria and tunisia), in: hamburger beitr~ge zur afrikakunde, vol. , hamburg ; a detailed bibliography on petrol a n d petrol economics is gsven in: oil in africa - a selected biography, africa documen- tation service, vol. , hamburg . following: all oil countries want to set up industries, in: petroleum economist, london, / , no. , pp. - . intereconomics, no. , forum pable of sustaining investments and also the requisite capital. [ ] producing countries with low per-capita incomes (indonesia, nigeria): owing to the large size of their populations the high oil revenues of these countries will either give rise to great social disparities and thus to political unrest or, if they are distributed relatively evenly, leave little scope for the accumulation of capital for industrial investments because of excessive demand arrears for consumer goods which are being met chiefly by imports. the evidence found in algeria is of general applicability for all oil producing countries in the second group which have populations and infrastructures capable of sustaining industrial investments. integration with the internal economy the domestic and external policy aims for the algerian economy are closely connected with the strategy which has been evolved for the country's raw materials and energy. ~ the principal aim is the economic, social and cultural advancement of the country which is insepar- able from industrialization. by industrialization alone can the required social standards be attained without creating an artificial prosperity lacking a productive basis and dependent entirely upon imports. as early as in the then president of algeria demanded that the oil industry should no longer be isolated from the other sections of the national economy and that the latter should be developed on the basis of the several contributions by arab and french authors may be quoted, notably a. g h o - z a l i and g. d e s t a n n e s d e b e r - n i s , les hydrocarbures et i'industrialisa- tion de i'alg~rie (the hydrocarbons and the industrialization of algeria), in: revue aig(~rienne des sciences juridiques (~cono- miques et politiques, / , no. , pp. - , and the memorandum presented by al- geria to the conference of opec sovereigns and heads of state, algiers, march . utilization of the hydrocarbon deposits (mineral oil and natural gas). a better way must be found, he said, for spreading the direct and indirect effects of industrialization over producing and consuming countries, and the natural resources must be made the starting point for the industrialization of the country in which they were found. this basic idea has been elaborated in collaboration with prominent economists so that algeria now feels justified to act as one of the spokesmen for the raw material-producing states of the third world. s oil and natural gas can have the following effects on the native economy: [ ] they can lower the cost of energy (motor fuel, gas, elec- tricity) for all demand sectors resulting, amongst others, in the attraction of industries with a high energy input. [ ] oil and natural gas can serve as primary materials for second- ary industries (refining, plastics, fertilizers, etc.). [ ] the local agriculture can be intensified through use of modern materials (fertilizers, chemicals, equipment). oil and natural gas however can produce these effects in the producing countries only if organisational steps are taken to give them a distinctive place in the internal economy in accordance with a plan which reflects the wishes of the producing country. from this follows inevitably a need for national control of the natural resources with a view to the optimum utilization of their direct and indirect potential, i.e., the external economic benefit to be derived by insistence on the highest possible prices for crude oil, and the domestic economic s cf. azzedine m a b r o u k i , l'o.p.e.c. et les tiers-monde - un m~me combat the opec and the third world - the same ruggle)o in: el djeich, algiers, no. , april , pp. - . benefit ensuing from the use of the inflowing capitals and the regional advantages, whether man-made or natural, for in- creased industrialization. the algerian state achieved a first integration objective by forming the soci~t~ nationale pour la recherche, la production, la transformation et la commer- cialisation des hydrocarbures (sonatrach) in december , , and the nationalization measures of february , , which gave the company a monopoly over transportation, oilfields operation and the whole natural gas sector. algeria's economic problems in common with all other de- veloping countries algeria has to cope with a multitude of prob- lems, especially [ ] low productivity in agri- culture and a consequent food deficit (about one-third of all imports consist of foodstuffs); [ ] a large manpower surplus pressing on the labour market (it is estimated that - p.c. of the potential labour force is unemployed or underemployed); [ ] mounting regional disparities between the favoured agricul- tural areas and traditional indus- trial localities on the coast, on the one hand, and the relatively overpopulated mountain and dry grassland regions which are in part still at a subsistence econ- omy level, on the other. these problems and the pros- pect of the exhaustion of the oil reserves in a generation or two create a need for far-reaching industrialization. this "industrial revolution" must go beyond what the industrialized countries are currently offering to the de- veloping countries on their own initiative (e.g. labour-intensive productions based on attrac- tively priced labour). in the algerian view the countries of the third world must be given an adequate share in the inter- intereconomics, no. , forum national amount of wealth pro- duced whereas a disequilibrium in the international division of labour would force them to be mere bystanders in the process- ing of their own raw materials, with the result that the added value produced by them would hardly cover the factor costs. the contribution of the oil industry in this respect is two- fold: [ ] the foreign currency earn- ings from exports of oil (and in future also of natural gas) are considerable. with a present output approximating mn tons a year ( ) p.c. of the whole investment outlay of dm bn under the four year plan for - can be met out of oil revenues. [ ] direct primary effects from the oil industry at the same time stimulate industrial development because it acts as a positive iocational factor. ideal industrial locations if the oil industry is sub-di- vided into its branches con- cerned with [ ] prospecting and production; [ ] transport and storage; and [ ] processing (refineries, petro- chemicals), prospecting and production are seen to provide only ephemeral benefits as is the nature of all mining operations, especially in developing countries . it is true that in the oases vilaya of al- geria, where all algerian oil is produced, the petroleum indus- try is the major industrial em- ployer (in it provided about p.c. of all industrial jobs although only p.c. of the total employment opportunities) and accounts for . p.c. of the total disposable incomes of employed persons (including value added cf., e.g., t. m ( e r , bergbau und regionale entwicklung in ostafrika (mining and regional development in east africa), in: afrika-studien, n o , munich . in agriculture), but the oil pro- duced cannot be processed on the spot because the production centres are too far from the national and international mar- kets and it is cheaper to trans- port crude materials than certain derivatives. the adverse climatic conditions of the sahara also militate against processing op- erations near the oilfietds. the iocational advantages due to the availability of oil and natural gas as energy and raw materials show up atthepipeline terminals and not in the produc- tion centres and along the trans- port routes (as a rule pipelines), the latter being capital-intensive but labour-extensive. terminals with favourable transport con- ditions offer an ideal location for industries based on hydro- carbons as raw materials and cheap energy sources if they enjoy other positive factors (labour, capital, accessibility) as well and receive due attention in national planning. this is brought out clearly by a com- parison of the development of different oil and natural gas pipeline terminals in north africa. the terminal of bejaia in algeria was operated by a for- eign company until ; that at skhira in tunisia is still under foreign management. neither of them had consequential regional effects apart from creating a small demand for labour for pipeline-to-ship transfers. it did not seem advisable to the har- bour undertakings to industri- alize the areas, perhaps by establishment of oil-based sec- ondary industries; the crude oil passed through without leav- ing any economic traces. it was not until the present year that algeria decided on the erection at bejaia of a . mn ton/year export refinery. the two other algerian coast- al terminals, at arzew and skikda, are to be integrated with the national and regional econ- omy. they are the terminals of pipelines for which the state- owned oil-gas monopoly com- pany, sonatrach, drew up the original plans. natural gas lique- faction plants, refineries and fertilizer factories (at arzew) and plants for basic materials for the plastics industry (skikda) and synthetic resins (arzew) have either been erected or are under construction. they already pro- vide direct employment for , and , relatively well-paid and highly-qualified workers - almost all of them algerians - and for even larger numbers indirectly as contractors working for the big state enterprises. attention to regional disparities while plants in coastal towns enjoy the best location for pro- ductions intended for export and home markets, their concen- tration in these towns would aggravate the regional dispar- ities. use is therefore being made of the manpower potential of the highlands and dry grass- lands, in which there has been little industrialization to date, for labour-intensive productions in factories working for the home market which draw on the coastal plants for primary mate- rials derived from oil and gas. projects in setif alone, which involve a total investment of da mn in plastics producing industry, will give direct em- ployment to about , workers by . the output of these plants, some of which have already been completed, will consist largely of consumer goods (household equipment, toys, packaging material, plastic furniture, floor coverings, etc.) and articles for agriculture (plas- tic sheeting, nets, boxes, buckets, etc.). new plants are also to be set up at el asnam. the algerian planners look on the coastal plants for the pro- duction of basic materials as developing poles around which secondary industries are to be intereconomics, no. , f o r u m grouped according to geograph- ical and other considerations. through downstream links (e.g. with the plastics industry) and feed-backs (e.g. to agriculture) they are to induce new industrial activities and in this way set off a kind of industrial chain re- action. price determination in the oil market an essential condition for the proper use of the oil and gas production as a lever or motive force for economic development in general is that [ ] the producing countries should gain control over the crude oil production; [ ] the natural resources should be used for large-scale indus- trialization; [ ] the industrialized countries should provide more financial and technological assistance for the development of the countries which have until now been pro- ducing nothing but raw mate- rials. algeria has been arguing for some considerable time that the prices must not be determined solely by the law of supply and demand as it affects the oil market. the factor costs of pro- duction, it is conceded, are low, but oil is an irreplaceable natu- ral raw material; once extracted, it is irretrievably lost to the pro- ducing country. there is a dif- ference, it is contended, be- tween normal industrial activities and the gifts of nature. the charges for the former are at the discretion of the producer. the benefit from the latter should go primarily to the pro- ducing country because the - foreign - producers and pro- cf. the memorandum presented by alge- ria at the opec conference, ibid., p. . e cf. a. b e n b e i i a , le polittque p(~tro- liars alg~rlenne (the algerian petro eum policy), in: revue alg~rlenne des sciences juridiques ~conomiques et politiques, no , , pp. - g. cessors would otherwise re- ceive an exorbitant return, s following the nationalization of the oil deposits and pro- duction, which has been carried through in one arab state after another since , the next step should be the industriali- zation of these countries on the basis of this raw material. as the opec states recently formu- lated it, "a substantial proportion of the oil processing (petro- chemicals, fertilizers) should be undertaken in the opec coun- tries with the (technological) assistance of the industrialized states to which a large part of the output should be exported. at the same time the industrial countries must do away with the discriminatory measures against industrial products from the developing countries." the translocation of oil-based indus- tries to the oil producing coun- tries may even result in ad- vantages (cost savings) for the industrialized consumer coun- tries. , the energy crisis was the first step to give practical effect to such concepts after the pro- ducing countries had come to realize that their industriali- zation could be based on oil as an energy and raw material. it was a surprise only for those observers who were not ac- quainted with the economic and political reality in the producing and exporting countries of the third world. where such a de- velopment may lead was shown by a remark attributed to the shah of iran: "(in another ten years) not a drop of iranian oil will be sold abroad, but western industrialized countries will be offered the chance to buy aspi- solemn declaration adopted by the first conference of opec sovereigns and heads of state on th march in algiers, in the memorandum presented by algeria at the opec conference, ibid., - . cf. farid a k h t a r e k h e v a r i , dle i~lpreispolitik der opec-lander (the oil price policy of the opec countries), in: probleme der weltwirtschaft, eiskuasions- beitrtige, no. , munich, no year ( ). rin and other chemicals from iran." ~ strategy for the future a process of emancipation and industrialization has been set in motion which will be pro- pelled forward by its momentum although the stagnation of the proceeds from crude oil ship- ments and the partial decline of prices (in algeria from $ a barrel in the first half of to currently $ and less) has shown to the selling countries that they cannot enforce their economic ideas regardless of the world market. it follows from what has been said that the algerian oil strat- egy, and by analogy the energy policies of the other populous oil producing countries will have the following aims in relation to the world energy market: [ ] exploration of all potential oil and natural gas deposits so as to gain a general view of the extent of these resources and the possibility of exercising con- trol over them. [ ] regulation of oil and natural gas production, not only as a function of the demand from the oil importing countries, but with a view to the satisfaction of local requirements. hence conserva- tion of the reserves and stabili- zation of oil earnings. such con- servation is the more important because oil and natural gas are a source of energy and, besides and especially, a raw material for the production of innumer- able important products includ- ing, for instance, the fertilizers which are indispensable to agri- culture. [ ] preservation of the purchas- ing power of the oil revenues. cf. k.-h. s t a n d k e , europe during the energy crisis", in: intereconomics, hamburg , no. , pp. - . t "algeria wants rapid industrialization", in: petroleum economist, london / , no. , pp. - . cf. the memorandum presented by al- geria . . . . lbld., pp. , . intereconomics, no. , forum [ ] preservation of the (external) purchasing power of the accu- mulated currency reserves. the crude oil production is stagnating in algeria as in most other traditional oil producing countries. in the potential annual output was still semi- officially put at mn tons. under the four year plan a pro- duction of mn tons is en- visaged, and this compares with an actual output (in ) of a little under mn tons. algeria is no longer one of the poor countries of the third world. the comparatively high revenues from the oil industry (an estimate for is da . bn) and the other natural, infra- structural and social conditions enable algeria to pursue an independent domestic and for- eign policyand to act as spokes- man in trade controversies be- tween industrial states and raw material producers. the coun- try's whole development strategy is based on a realistic assess- ment of the internal economic situation. directly or indirectly the actual and potential regional effects of the activities con- nected with the algerian oil oc- cupy a prominent place in al- geria's strategy. oil problems seen from the arab point of view by aziz alkazaz, hamburg* t he discussion about the problems involved in deter- mining the price of crude oil as a source of primary energy has been dominated until now by aspects bearing on its reper- cussions on the balances of payment and economic develop- ment of the industrialized coun- tries. this one-sided approach can lead to wrong decisions which would have grave conse- quences for the further develop- ment of the world economy. that the industrial states have come in for "unpleasant sur- prises" in the course of the so- called energy crisis is essentially due to the fact that their energy policies in the past score of years were governed by two basic objectives, namely: [ ] to obtain the oil at the most favourable price, and [ ] to make sure of regular supplies. the interest of the oil produc- ing states and other raw material countries, on the other hand, were neglected. the current problems cannot however be " german orient institute. solved unless the mutual inter- ests of all the parties concerned receive full consideration. in dealing with the problem of price determination it is advisable to make the medium- and long-term availability of the energy materials on a global scale the starting point. in the last two decades the world energy consumption has been increasing at an average rate of p.c. per annum, and the contribution of mineral oils to the total energy supply doubled between and , from to p.c.; the petroleum thus bore the brunt of the rising world demand for energy. the fact that the oil prices had been kept down to a low level for years was relevant to the rapid expan- sion of energy consumption and the simultaneous substitution of mineral oils for solid fuels. the low price of oil enabled the industrial nations to develop their growth industries on the basis of cheap energy, but made it impossible to develop substitute energy sources and energy-consuming technologies in good time. in the last seven years alone the world has been using up bn barrels of crude oil ( barrel = litres) - an amount equal to about one-sixth of the total proven reserves of bn barrels at the end of . in this time the world used more oil than it had done in the preceding years, from to . its total usable reserves would last years at present output rates (compared with years in ). if, as was forecast before the recent price increases, world oil consumption were to increase by . p.c. annually until , no less than bn barrels of oil reserves would have to be found in the ground in the next seven years merely to maintain the same ratio of reserves to consumption. that however is inconceivable. on the assumption that the world oil reserves can be augmented at rates of , or p.c. a year and world oil production increases by p.c. annually, the world output would on technical grounds go into a steep dive in , or years respectively. intereconomics, no. , the advantages and disadvantages of the production of shale gas potential: the case of turkey turgut bayramoĞlu dr. bayburt university, economics department, bayburt tel: + , tbayramoglu@bayburt.edu.tr yilmaz onur arİ (corresponding author) research assistant, bayburt university, economics department, bayburt tel: + , yoari@bayburt.edu.tr abstract:- energy is a main input for economy. because of an increase in other fossil fuels’ prices and it’s accepted as an important resource for energy supply for the countries which don’t have enough oil and natural gas resources, shale gas became a current issue in the world. technically producable shale gas in the world is about . bcm (billion cubic meter). we can say that this amount may be higher if unsought areas are added. turkey is one of the countries which has shale gas potential. according to a report published by eia in , turkey has approximately billion cubic meter shale gas reserves. this shale gas potential can reduce turkey’s energy dependence if we think of the fact that annual natural gas consumption of turkey is bcm. despite all, production of shale gas has not been searched in terms of it’s advantages and disadvantages. the aim of this study is to present the advantages and disadvantages of shales gas for the world and turkey. reducing energy dependence, supporting a more clean energy than coal, balancing the oil prices are some advantages. nevertheless, it’s a fossil fuel, it’s production is expensive and it gets negative social and environmental reactions. key words: shale gas, energy economics, turkey, advantages and disadvantages of shale gas. . introductıon energy is a main input for economic activities. energy is defined as a capacity for doing business and accepted as a power behind every sort of energy and everthing that was changed (stern, : ). in literature, the concept of energy was discussed as an ability of doing business for human and animal until industrial revolution. then industrial revolution caused the usage of steam engine and coal for producing iron. after first world war, oil and natural gas have been used instead of human and animals (bayramoglu, : ). although energy is used in every part of life, it’s economic aspects are discussed under a sub-branch of economy, energy economics in this study. investments and activities to reach natural energy resources provide an increase in accumulation of energy and it’s usage in economic activities. therefore energy is driving force for the development of countries and has importance for countries’ strategic positions (ladanaiandvinterbäck, : ). after energy crisis in s, alternative energy resouces have been sought. because the reasons like advancement of technology, reduction of costs, international pipeline projects, supporting the security of supply and increasing energy demand day by day; shale gas potential has been analyzed and started to produce. shale gas is expected to replace other fossil fuels in , and its production is expected to be higher than coal production in the near future (energyinstitute, access date; . . ). despite all these developments, shale gas is a fossil fuel. therefore, shale gas is a harmful energy resource for human health and environment from production to final consumption periods. the aim of this study to present the shale gas potential in turkey and discuss the advantages and disadvantages according to other energy resources. this article will end with conclusion and suggestions. mailto:tbayramoglu@bayburt.edu.tr mailto:yoari@bayburt.edu.tr . shale gas potentıal in the world and turkey energy demand is increasing day by day both in the whole world and turkey. it’s expected that global natural gas demand will be rapidly increase depending upon its industrial and urban utilization. it’s estimated to reach trillion cubic meter in while natural gas demand was trillion cubic meter in (demirbas, : ).energy crisis in the past compelled the whole world for new energy resources. shale gas is one of them. shale gas has been considering as an alternative energy resource especially in usa after developing new technologies and innovations which reduce the cost of its extraction. shale gas is a type of energy resource which is among the sedimentary rocksthat consist of clay-like minerals with rich organic substance. it can be extracted by horizontal drilling and hydrolic-break method and also it’s among non-conventional energy resources (İea, ). after sharp increases in oil and natural gas prices, shale gas became popular in the worldas a result of alternative energy searching of developed countries and the lack of energy supply in these countries (asche, oglend ve osmnundsen, : ). drilled oil-wells in the world increase every passing day. in usa, there are thousands of drilled oil-wells but there are less than hundred in china (centner, t.j. ve o’connell, l.k., : ). usa managed to produce more shale gas than it’s imported natural gas. these values show that us will soon get out of energy dependence thanks to shale gas. shale gas is not a new subject, especially for some countries. for example; usa, canada and china have been producing for a long time. today usa is the country which produces the most shale gas among the countries which have shale gas potential. shale gas has a power to change the world energy prospect if it’s potential is used efficiently as an energy resource. according to a report by eia, shale gas production in usa is % of total production of natural gas and oil and shale gas has a potential to support the half of gas production until . according to estimates made by eia, the countries that have the most shale gas potential are; after sharp increases in oil and natural gas prices, shale gas became popular in the world as a result of alternative energy searching of developed countries and the lack of energy supply in these countries. when table- analyzed, it is clear to say that total technically recoverable shale gas potential in the world is . bcm and first shale gas producer countries have a potential of . bcm. it’s estimated to reach . bcm today (iea, ). china has . % per cent of recoverable shale gas potential. usa ( %), argentina ( . %) and mexico ( . %) follows china respectively. turkey’s shale gas potential has % . of world total. it’ll absolutely make a positive effect to reduce turkey’s energy dependence although the amount of shale gas potential is not too much. turkey’s energy demand has been increasing in recent years and it’s expected to continue to increase in the future. according to the report published by eia in , turkey’s recoverable shale gas reserve is about bcm (demirbas, : ). as figure- shows, most of this potential is located atsoutheast anatolia (dadas basin) and trakya region (hamitabat and mezardere)as estimative areas. also there are shale gas basins near salt lake and sivas basins but they are non-estimative. with an agreement between tpao and shell, if explorations become successful in mediterranean region, this known potential will be able to be drilled in turkey (tpao, ). despite different estimations about turkey’s shale gas reserves, when it is considered that turkey’s annual energy consumption is about bcm, it is possible that this shale gas potential can support at least - years of turkey’s energy need (kozakoglu, ).on one hand increasing energy demand requires the drilling of shale gas, on the other hand increasing environmental consciousness and negative impact of fossil fuels prevent the production. advantages and disadvantages of producing shale gas are valid not only for turkey, but also for the world. . literature summary in literature studies, shale gas and shale oil’s potential in the world, their roles on supporting the world energy need and finally their economic, politic and environmental effects were discussed with their advantages and disadvantages. there are many studies about shale gas and shale oil. we can give some examples (altun vd., ; hepbaşlı, ; boyer vd., ; selley, ; weijermars, ; ahıshalı, ; eia-ari, ; armor, ; hu ve xu, ; johnson ve boersma, ; centner ve o’connell, ) from the world. boyer et al. ( : ) in their study claimed that shale oil reserve estimations made by eia in are much more than estimations made by roger study in . in the study shale oil were discussed as a global energy resource and shale oil potential was analyzed all over the world, especially in developing countries such as china, india, south africa and argentina. selley ( : - ) analyzed the shale gas and oil potential in england. weijermars ( : ) emphasized the importance of shale gas for europe in terms of its economic potential. accordingly, there are about - bcm technically recoverable shale gas reserves in europe. in addition to shale gas and shale oil’s potential in the world, there are also studies about their potential in turkey in the literature. it’s stated that there are intense shale oil potential in south-east anatolia basin and trakya basin and also there may be shale oil reserves in interior parts of black sea region and toros basin (ahıshalı, : ). also altun et al. ( : - ) claimed in their study that shale oil has the second most fossil fuel potential after lignite in turkey. in the study benefits of shale oil and gas for turkish economy were analyzed. eia-ari ( : ) in the report named ‘’shale gas and shale oil resource assessment’’ points out that there are billion barrel shale oil and . billion barrel risky but technically recoverable shale oil resources in anatolia and trakya basins in turkey. also in the same report it’s added that there are trillion cubic meter shale gas potential and trillion cubic meter recoverable shale gas potential in turkey. there are many studies about advantages and disadvantages about shale gas and shale oil in literature. hepbaşlı ( : - ) mentioned about tarry shale oil fields in turkey and added that fluidized ones can be profited for generating electricity. it was stated that fluidized shale oil was a good tool for igniting various combustibles from wood to hard coal and it has being used since s in industrial area, but it wasn’t preferable because mining cost from shale oil fields were higher than the cost of crude oil. armor ( : - ) emphasized the fact that the usage of shale gas as dynamic and chemical were more environment-friendly than petroleum and coal. altun et al. ( : ) explained that the ash of shale oil was used as a raw material of cement in china today. also it was predicted that a development at the production of shale gas will cause serious environmental disasters and water scarcity in china without taking measures towards environmental pollution, using advanced technology, providing balanced water consumption, preparing a good relationship between industry and local community (hu ve xu, : - ).johnson ve boersma ( : - ) referred the economic, politic and environmental problems which are possible to encounter for poland, which is a country that begins to build its shale gas industry. it’s emphasized that polish people won’t be non-reactive to fast hydrocarbon emission just like north americans. in addition to this, development in shale gas industy may increase the tension between poland and russia. centner ve o’connell ( : ) claimed that an increase in air and water pollution may prompt new technologies, innovations and job opportunities in health and environment protection sectors. . advantages and disadvantages of shale gas although shale gas has been known before, negative or positive results of its production are not still certain. shale gas is a fossil energy resource. it carries all negative effects of a fosil fuel, but also it offers someopportunities as a new energy resource. its positives are: it reduces the energy dependence, it can be used instead of coal which is more contaminant than shale gas, it balances the oil prices, it breaks the monopoly of oil exporting countries, it has the power of providing employment and it has the power of improve the economic indicators. it’s negatives are shortly: it is a resource which quickens the global warming, it may be one of the reasons of earthquake, its production is highly costly, may pollute the water sources, negative environmental and social reactions and continuity of the usage of fossil fuels. the main advantages of producing shale gas: - it reduces the energy dependence: turkey, for example, is a country which import over billion dollars energy every year. china is also dependent to imported energy. china’s technically shale gas production potential is approximately . bcm. turkey’s is around bcm. it is expected that if countries which are dependent to imported energy and have shale gas potential, use these resources for energy, they diminish their energy dependence(ee, ). according to estimations made by ogt, shale gas will reduce europe’s energy dependence about % in (ogt, ). - it can be used instead of coal which is more contaminant than shale gas: shale gas can be stay in diagenesis in good condition for many years. it is drilled by hydrolic breaking method. therefore it’s a new resource to get coal gas and also it can be easily substituted for coal. china gets % of its energy need from coal. if china uses its shale gas potential, it can pollute the environment less and take the heat off the rest of the world (xingang, jiaoli ve bei, : ). - it balances the oil prices: oil prices are expected to decrease in case of using shale oil and gas potential by the countries which have shale reserves. usa beginned to produce shale gas and it has already showed its effect on prices (eİa, , medlock iii, : ,johnson ve boersma, : ). - it breaks the monopoly of oil exporting countries: usa and china are the biggest oil exporting countries. also they have the biggest shale gas potential. this dual structure will cause the income of oil exporting countries decrease. especially arabic countries will be affected badly(medlock iii, : ). - it has the power of providing employment: it is projected that producing shale gas will contribute to grow employment globally. for example in texas state, . people are employed in shale gas sector. it’s estimated that shale gas will create more than . people employed in england. according to ogp, in the long term shale gas will make more than . million people employed in europe (ogp, ). - it has the power of improve the economic indicators: it’s expected that shale gas production will increase competition and reduce the imported energy dependence in the region and also it provides . - . trillion euros for european economy between the years - (ogp, ). the main disadvantages of producing shale gas are: - it is a resource which quickens the global warming: it’s recommended to use renewable energy resources and to stop carbon emission before global warming exceeds the critic line for any living thing. environmentalists and climate change experts mentioned their worries about production of shale gas. as a result of this development, many governments like french government* banned the drilling of shale gas. while drilling shale gas, carbon emission is . %- % more than conventional gas (filoğlu, : ). - it may be one of the reasons of earthquake: drilling the shale gas is made by hydrolic cracking method. this method causes spaces undergound thus it is thought one of the reasons of earthquakes(filoğlu, : ). besides, experts point out shale gas as a responsible for small earthquakes in weeton, england. - its production is highly costly: drilling ofshale gas is two times more expensive than natural gas because the existing technology is still so expensive and there is no other suitable technology for shale gas. - it may pollute the water sources: shale gas is a resource drilled by hydrolic cracking method and some chemicals are used during the application of this method. there are some worries about some chemicals may mix in underground water(hu ve xu, : ). environmentalists, claims that chemicals which occurs after drilling shale gas, may pollute water sources. another problem about water is using too much water while drilling shale gas. tons of water is used while a standard well bore but . tons for shale gas drilling (xingang, jiaoli ve bei, : ). water purification of used water can be provided by new technologies but cost of purification and too much water use are two negative factors for underground water.(yıldız, : ). - continuity of the usage of fossil fuels:oil, natural gas and coal will run short one day, even if these are different dates. the usage of these resources should be lowered to reduce environmental pollution. fossil fuel usage will continue for many years by the help of turning shale gas potential into production(filoğlu, : ). also other disadvantages of using shale gas are: negative environmental and social reactions, infringement of habitat, environment pollution, changes in underground structure, disputes between global companies and local residents etc. (hu ve xu, : , filoğlu, : ). . conclusion and assessment * french constitutional council approved the law in july , which banned shale gas drilling. all countries have to produce in order to increase their income. energy is an indespensable factor for production. energy crisis refers countries to different energy resources. shale gas is one of them. shale gas wasn’t produced until last few years due to the lack of technology, cost of its extraction and its unknown potential. now today shale gas is considered as an important energy resource. shale gas has a big potential to produce energy primarily for china and usa. usa beginned to evaluate this potential and other countries do scientific researches for shale gas production. technically recoverable shale gas potential is . bcm and turkey’s potential is bcm. thanks to countries’ interests in shale gas and abundance of recoverable shale gas potential in the world, its advantages and disadvantages come into prominence. on one hand shale gas gives especially environmental damages because it’s a fossil fuel, on the other hand it has some benefits because it has potential to support energy supply security. in this study its possible advantages and disadvantages were discussed as a result of turning shale gas potential into production. the results show that even if its potential and and its production opportunities are known, its advantages and disadvantages should be considered. references [ ] ahıshalı, m.a. 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[ ] yıldız, d., ( ), “kaya gazı devriminin gücü: su”, rapor no: ,s. . http:/ topraksuenerji.org. table : technically recoverable shale gas potential (billion cubic meter) source: eİa, world shale gas resources: an İnitial assesment of regions outside the united satates, http://www.eia.gov/analysis/studies/worldshalegas/ e.t. . . *turkey’s and lithuania’s potentialat most billion cubic meter.according to estimations by turkish petroleum corporative (tpao) it’s bcm for sought areas. *total per cent may not be % due to rounding off. figure- : map of world shale gas potential number country shale gas potential per cent (%) china , , usa , argentina , mexico , south africa , australia , canada , libya , algeria , brazil , poland , france , turkey * , lithuania * , others , world total , http://www.eia.gov/analysis/studies/worldshalegas/% e.t http://www.google.com.tr/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact= &docid=t_eob_c_wxyq m&tbnid=vzmc- itks unm:&ved= cayqjrw&url=http://www.potaforum.net/ediz-hunla-yesil-sayfa-t p .html&ei=azkwu k cm j awyvydwdw&bvm=bv. ,d.bge&psig=afqjcnfsw gk z _zwk mqycotkv ip qa&ust= source: eİa, http://www.eia.gov/analysis/studies/worldshalegas/, e.t. . . figure- shows where the shale gas potential is in the world. as figure shows, world potential has a power to change energy prospect in the future. figure- : shale gas potential of turkey source: tpao, http://www.tpao.gov.tr/tpfiles/userfiles/files/ -sektor-rapor-mayis-tr.pdf, a.d. . . http://www.eia.gov/analysis/studies/worldshalegas/ http://www.tpao.gov.tr/tpfiles/userfiles/files/ -sektor-rapor-mayis-tr.pdf http://www.google.com.tr/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact= &docid=gkdhaydo c vzm&tbnid=s pm pjfew m:&ved= cauqjrw&url=http://www.shaleexperts.com/plays/turkey-shale/?menu&ei=cj du kpdmpatabi ygiag&bvm=bv. ,d.bgq&psig=afqjcnhei rr rglgiz_mg jgsrwhua&ust= the erythrocytic hypothesis of brain energy crisis in sporadic alzheimer disease: possible consequences and supporting evidence journal of clinical medicine review the erythrocytic hypothesis of brain energy crisis in sporadic alzheimer disease: possible consequences and supporting evidence elena kosenko ,* , lyudmila tikhonova , gubidat alilova , amparo urios and carmina montoliu , institute of theoretical and experimental biophysics of russian academy of sciences, pushchino , russia; ljudasik @rambler.ru (l.t.); hells @yandex.ru (g.a.) hospital clinico research foundation, incliva health research institute, valencia, spain; aurios@cipf.es (a.u.); carmina.montoliu@uv.es (c.m.) pathology department, faculty of medicine, university of valencia, valencia, spain * correspondence: eakos@rambler.ru or gieraki@mail.ru; tel.: + - - - - received: december ; accepted: january ; published: january ���������� ������� abstract: alzheimer’s disease (ad) is a fatal form of dementia of unknown etiology. although amyloid plaque accumulation in the brain has been the subject of intensive research in disease pathogenesis and anti-amyloid drug development; the continued failures of the clinical trials suggest that amyloids are not a key cause of ad and new approaches to ad investigation and treatment are needed. we propose a new hypothesis of ad development based on metabolic abnormalities in circulating red blood cells (rbcs) that slow down oxygen release from rbcs into brain tissue which in turn leads to hypoxia-induced brain energy crisis; loss of neurons; and progressive atrophy preceding cognitive dysfunction. this review summarizes current evidence for the erythrocytic hypothesis of ad development and provides new insights into the causes of neurodegeneration offering an innovative way to diagnose and treat this systemic disease. keywords: alzheimer’s disease; amyloid β peptides; brain energy crisis; erythrocytic hypothesis; red blood cells; restoration of energy metabolism . introduction alzheimer’s disease (ad) is a progressive systemic disorder that develops slowly attacking the brain, brain blood vessels, and peripheral tissues [ ], as well as red blood cells (rbc) [ , ], platelets [ ], and leukocytes [ ], and is characterized by progressive deterioration in cognitive abilities including memory impairment, typically in the elderly. in %– % of cases ad develops sporadically, and according to statistics on this type of dementia, about % of people aged have the disorder [ ]. unless a way is found to halt progression of this disease, and if the population continues to grow, it is believed that by the number of people worldwide with this illness will be close to million people, . million new patients per year, meaning that someone in the world will develop ad every s [ ]. although during recent decades significant progress has been made in presenting different hypotheses of sporadic ad [ – ], the underlying mechanisms of the disease need further scrutinity. the “amyloid cascade hypothesis” [ ] has greatly influenced research over the last twenty years with considerable effort devoted to designing new anti-amyloid drugs, and although there is still no cure for ad [ , ], this hypothesis remains the most prevalent. nevertheless, the key points of the hypothesis suggesting a central role for amyloid plaques in disease development and considering j. clin. med. , , ; doi: . /jcm www.mdpi.com/journal/jcm http://www.mdpi.com/journal/jcm http://www.mdpi.com https://orcid.org/ - - - x https://orcid.org/ - - - https://orcid.org/ - - - http://www.mdpi.com/ - / / / ?type=check_update&version= http://dx.doi.org/ . /jcm http://www.mdpi.com/journal/jcm j. clin. med. , , of the brain and its age-related changes independently of the blood flow are paradoxical rather than convincing. the main reason is that the idea behind the “amyloid cascade hypothesis” is not consistent with the known axiom stating that even a short pause in glucose and oxygen inflow to the brain causes its damage and chronic deficiency in these substrates can ultimately lead to irreversible brain damage affecting cell viability and activity, and further promoting permanent cognitive impairment [ , ]. understanding the mechanisms through which aerobic glucose metabolism is disturbed in the brain is clearly of paramount importance. many mechanisms are involved in impaired glucose oxidation in the brain affected by ad [ ]. it is noteworthy, however, that earlier studies were mostly conducted using autopsy brains from ad patients as the object of examination [ , ], making it difficult to unravel the true mechanisms of the failure in brain energy metabolism, since many factors influence results obtained using postmortem brain tissues, including the agonal stage, brain storage time and temperature protocol, and lactate accumulation [ , ]. therefore, no possible correlation between the ascertained causes of the impaired glucose utilization and clinical symptoms of the disease has been identified [ ]. by contrast, with functional brain imaging techniques for measuring brain metabolic fluxes in vivo [ , ] it is possible not only to identify the brain regions with significant reductions in glucose metabolism but also to predict memory impairment in people with normal cognitive functions long before the clinical symptoms appear [ – ]. thus, there is evidence supporting the view that the reduction in blood-carrying energy substrates, particularly glucose and oxygen observed in vivo in ad, results directly from cerebrovascular pathology [ ]. this ultimately leads to energy collapse followed by the functional brain failure, and as a consequence, cognitive impairment [ , ]. another essential factor contributing to brain oxygenation is the oxygen-carrying capacity of red blood cells. it is known that the role of rbcs in tissue oxygen delivery depends on their intracellular metabolism, primarily via energy metabolism and antioxidant status [ , ], which regulate hemoglobin oxygen affinity [ ] and no-dependent hypoxic vasodilation [ – ]. numerous studies have shown that normal rbc parameters might be significantly affected in ad patients. for instance, in ad patients rbcs have been found to exhibit morphological changes [ , ], leading to decreased deformability [ ], perturbations in the physical state of membrane proteins [ , ], and oxidant/antioxidant equilibrium [ – ]. these changes are in some way due to the destabilization of intracellular metabolism in erythrocytes [ – ]. however, the mechanisms underlying the foregoing alterations in rbc metabolism in ad patients are not fully understood. furthermore, ad is still thought to be exclusively a brain disorder, so a link between disruptions of the endogenous metabolic pathways in circulating erythrocytes that slow down oxygen release, and brain energy crisis manifested as poor brain aerobic glucose oxidation which may precede neurodegeneration is not sufficiently discussed in the literature. in this article, we review current evidence in support of the widely known amyloid cascade hypothesis and seek to uncover new perspectives on the cause of sporadic ad development, considering brain amyloids outside pathology and suggesting a new mechanism by which neurodegeneration may occur. based on our and available published data [ – ] we hypothesize that abnormalities in endogenous glycolytic, antioxidant, and transport pathways in circulating erythrocytes in individuals entering old age [ ] disrupt red blood cell function associated with oxygen supply to the brain. this causes deterioration in the aerobic oxidation of glucose leading to the nerve cell degeneration and impaired cognitive processes observed in ad [ ]. this assumption is not in contrast with the vascular hypothesis predicting neurodegeneration as a result of impaired blood circulation and brain hypoperfusion [ – ]. on the other hand, it clearly indicates the possible existence of another unknown mechanism which restricts oxygen supply to the brain, and therefore participates in the development of hypoxia and neurodegenerative processes specific to ad. j. clin. med. , , of consequently, we believe that changes in endogenous biochemical parameters in erythrocytes can be considered both an indicator of cell state in the central nervous system, and a new target to develop innovative treatment methods for systemic disease such as ad. this suggestion provides a basis for developing individual innovative technologies to restore energy metabolism, the antioxidant system and other impaired endogenous biochemical pathways in erythrocytes [ ]. this will help improve rbc function to provide an adequate oxygen supply to the brain and normalize aerobic glucose utilization. . evidence that contradicts the fundamental principles of the amyloid cascade hypothesis . . brain amyloid plaques and soluble aβ oligomers are unspecific for ad the fact that cerebral amyloidosis is generated during many human diseases has been knоwn for more than a century, when amyloids (aβ) were found in the brain and cerebral vessels of a yоung woman with cognitive dysfunction caused by traumatic injury to the head [ ]. almost simultaneously, researchers discovered that aβ deposits are formed and stored in the brain in patients with other pathologies [ , ]. these facts indicate that cerebral amyloidosis does not depend on age and may occur in people without dementia. the latest research results are consistent with data obtained in previous studies which indicate that aβ peptides are non-specific for ad and accumulate in the brain of children and adults with many acute and chronic central nervous system disorders [ – ], as well as in normal non-demented elderly persons [ , ]. further, in some individuals, aβ levels in the brain are comparable to or even higher than is typical in ad patients [ , ]. moreover, a close correlation between severity of cognitive dysfunction and total amyloid volume in the brain of ad patients is not generally detectable [ – ]. taken together, these results suggest that neither the density of amyloid plaques nor the absolute amount of amyloids can predict cognitive dysfunction impairment or disease onset [ ]. these findings contradict the amyloid cascade hypothesis, which states that “deposition of amyloid β protein, the main component of the plaques, is the causative agent of alzheimer’s pathology and that the formation of neurofibrillary tangles, cell loss, vascular damage, and dementia follow as a direct result of this deposition” [ ]. soluble aβ oligomers, which according to the modified amyloid cascade hypothesis are the initiators of the fatal cascade in ad [ , ], have also been detected in the brains of healthy elderly individuals [ , ]. moreover, the increase in soluble aβ level in ad patients compared with healthy normal subjects is negligible [ ]. at the same time there is evidence indicating that the accumulation of soluble aβ oligomers in the brains of patients with ad is episodic with no direct correlation between this accumulation and the appearance of clinical symptoms of the disease [ ]. in addition, after the discovery of soluble aβ oligomers in brains of patients with down’s syndrome [ ] and traumatic brain injury [ , ] it can be assumed that soluble aβs like aggregated aβ peptides are unspecific fоr ad prompting a search for new pathogenic factors. . . aβ neurotoxicity: which peptide is a therapeutic target the toxicity of amyloid peptides is the main argument supporting the amyloid cascade hypothesis. however, it must be acknowledged that data on toxicity of amyloid peptides are obtained exclusively from in vitro experiments [ – ], while participation of amyloids in neuronal death has not yet been demonstrated in vivo. indeed, numerous studies conducted in vitro have shown that amyloids induce changes in neurons leading to numerous disorders incompatible with cell vitality. as an example, in primary neuronal cultures neurotoxicity is associated with channel formation in the membrane [ , ], increased metal-dependent production of reactive oxygen species, and oxidative stress [ ]. additionally, interaction between amyloids and cells leads to changes in activity of membrane-bound proteins [ ] and receptors [ ], in dynamic properties of lipids [ ], and loss of phospholipid j. clin. med. , , of asymmetry and integrity [ ], that in turn increases membrane fluidity [ ] and permeability [ ]. the damaging effect on the membrane structures causes dysfunction of the ion pumps and a consequent increase in intracellular calcium [ ] triggering a glutamate-dependent pathological cascade that results in further cell death [ ]. interestingly, in vitro both soluble aβ oligomers and aggregated aβ forms induce cell death in virtually any cultured cell type, and cell death occurs within a few minutes of exposure to amyloids. a number of questions arise about the significance of these data. for example, if amyloids are so toxic that even a short-term interaction between the cell and amyloid causes the death of the former, how can these amyloids be “silent” in the brain of ad patients for so long time ( – years) before the appearance of the first clinical symptoms of the disease [ , ]? if amyloids are toxic, how can people with this disease live to a very old age and make up the largest group of total cases people aged over [ ]? and more, if amyloids located in the brain of elderly individuals with normal memory are toxic why do these toxic substances not affect intellectual capacity, work ability and cognitive processes to a ripe old age? it is clear that the in vitro study results do not always provide easy answer to any of the questions raised. the issue of amyloid toxicity was not clarified by findings from studies carried out in vivo either. it has been shown that isolated plaque cores from postmortem ad brains [ ] and synthetic aβ fragments produced ad-like neuropathology in vivo [ , ]. a similar effect was observed for soluble aβs [ ], which according to the reformulated “oligomeric amyloid hypothesis” are the principal neurotoxins [ ]. in addition, both peptides disrupted learned behavior in normal animals [ , ]. these observations again raised the question of which hypotheses is correct and what peptide should be a therapeutic target, to which the answer would appear to be an aggregated one as all transgenic mouse models [ ] as well as transgenic drosophila models [ ], or even transgenic strain of the nematode caenorhabditis elegans [ ], used for screening of anti-amyloid drugs, develop only aβ aggregates [ ], ultimately leading to plaque formation [ ]. the amyloid cascade hypothesis [ ] and the oligomeric amyloid hypothesis [ ] evidently contradict each other [ ], thereby lowering the level of a huge body of data obtained via in vitro and in vivo studies. thus, the question remains open as to the toxicity of amyloids in vivo and the expediency of designing new drugs based on contradictory hypotheses which are associated with a pathogenic factor whose toxicity has not yet been proven [ ]. . . can transgenic rodents be used as a suitable model for sporadic ad returning to the amylоid cascade hypоthesis, which was originally postulated for the genetic form of the disease [ ], it should be kept in mind that detection of app and presenilin gene mutations [ ] in the genetic form of ad was the only strong evidence underlying the amyloid hypothesis [ ]. however, there was no evidence proving that amyloids are the only cause of this disease, especially its sporadic form [ ], in which there are no such gene mutations, but instead increased amyloid synthesis which leads to accumulation, aggregation and amyloid plaque formation, characteristic of genetic disease. interestingly, that by creating an amyloid cascade hypothesis, d. hardy assumed that “the mutations in app so far described are responsible only for a small proportion of cases of alzheimer’s disease. indeed, most cases of alzheimer’s seem to occur in a sporadic fashion, suggesting that there must be other causes of the disease. the cascade hypothesis suggests that other causes of alzheimer’s act by initially triggering app deposition. this deposition could be caused by an induction of the app gene through an interleukin-mediated stress response because app increases in response to a number of neuronal stresses” [ ]. a review of the literature sheds no light on when or by whom the role of genetic mutations was first considered in the pathоgenesis of sporadic form of ad. apparently confusion has arisen concerning the hypothesis: it was proposed only for the genetic form of ad, and all anti-amyloid preparations were tested on transgenic mice, using the so-called genetic mouse models of ad, but clinical trials only recruited patients with sporadic disease [ ], without mutations in the abovementioned genes. further, despite the fact that all types of transgenic models perfectly imitate the amyloid aspect of ad [ ], the relationship j. clin. med. , , of postulated by the amyloid cascade hypothesis between enhanced amyloid formation and accumulation of hyperphosphorylated tau protein, memory impairment, and neuronal death, is not generally confirmed, using transgenic models [ – ]. moreover, the memory impairment and neuron death that occur before the appearance of amyloids in the brains of transgenic animals [ , ] may indicate that artificially introducing alien genetic information into the genome of animals might have unexpected pathological effects on the brain and the body as a whole. this prediction is verified by the hippocampal (and other brain regions) hypometabolism and atrophy observed prior to plaque formation [ ] and premature deaths in transgenic mice [ ], most probably due to the cerebral energy crisis resulting from artificial introduction of alien transgene rather than from accumulated amyloid peptides [ ]. moreover, this fact points to the presence of unrevealed problems that usually arise when creating transgenic models. in fact, overexpression of app in transgenic animals can dramatically disrupt the mitochondrial function [ ] resulting in enhanced oxidative stress [ ], uncontrolled release of neurotransmitters [ ] and cell death via the apoptotic pathway. this indicates a need to identify the pathological changes occurring in the brains of transgenic animals prior to augmented amyloid formation and whether changes in the behavioral responses of transgenic animals result from the accumulation of amyloids, rather than app-inducing brain hypometabolism. the genesis of degenerative processes and memory impairment before the appearance of amyloids in the brain, and the premature death of transgenic animals preclude using these animals as adequate models of sporadic ad [ ]. this view is supported by a large body of clinical trials showing negative effects, and even death in sporadic ad patients who received anti-amyloid preparations [ , – ], despite their therapeutic effect having been confirmed in transgenic mice [ – ]. it is clear that any animal model has its advantages and disadvantages, but patients’ lives depend on a model that meets the main requirement of equivalent action in animal models and patients and development of safety drugs. certainly, the approach in research to the problems of the sporadic form of ad seems poorly planned demonstrating a logical gap in the “hypothesis–objective–test” chain which leads to a focus only on amyloids. in fact, it is clear that if aβ deposition occurs in response to cerebral hypometabolism in even young transgenic animals [ ], and in elderly ad individuals [ , ], a search for factors that trigger pathological processes in murine and human brains, which in turn lead to app overexpression and aβ accumulation, is of crucial importance in current biomedical research. . brain energy crisis and aβ accumulation: cause or consequence glucose is the main brain energy metabolite, the precursor of substrates that are oxidized in the mitochondrial tricarboxylic acid cycle to form atp [ ]. glycogen is the only endogenous source of glucose in the brain, but since its reserves are extremely small and the brain is unable to synthesize glucose de novo quickly enough [ ], brain cell viability and its myriad functions are completely dependent on a continuous supply of glucose via blood flow. in addition to atp, other important energy substrates, for example, lactate produced by glucose metabolism are used by neurons as an additional energy substrate when metabolic activity is high [ , ]. glucose carbon can be included in lipids [ ], proteins [ ], and glycogen [ ] and is also a precursor of some neurotransmitters such as γ-aminobutyric acid, gaba [ ], glutamate [ ], and acetylcholine [ ] as well as nicotinamide adenine dinucleotide phosphate reduced (nadph) essential for maintaining brain antioxidant capacity [ ]. thus, glucose entering the brain from the blood is the main substrate known to regulate numerous brain functions, including brain activity, learning, memory [ ], and nerve cell viability in general [ , ]. glucose oxidation in the brain is suppressed with age [ , ], but in individuals without chronic diseases or silent brain pathology, a decrease in metabolic rate usually comes with almost no symptoms, and elderly people can live long enough in relatively good physical and mental health. by contrast, in sporadic ad aerobic oxidation of glucose and the rate of atp formation in the brain decrease j. clin. med. , , of dramatically [ ] resulting in damage to nerve cells and influencing neuronal function and mental states [ , ]. as is known, neurons in different brain structures are not equally sensitive to glucose shortage. therefore, it is not a surprise that in ad all glucose-dependent neurons, localized in the hippocampus and neocortex [ ], involved in the process of long-term memory storage [ ], are damaged to a large extent in a state of glucose deprivation. interestingly, significant accumulation of amyloid peptides is revealed in these brain regions in ad patients [ ] suggesting that glucose deficiency is related to increased amyloid formation in the brain. it is obvious that the causes of amyloid proliferation in the brain in the sporadic form of ad should differ from those described for the genetic form of the disease, if only because app and presenilin gene mutations are not observed in sporadic ad. assuming there is a relationship between disturbances in glucose metabolism in the brain and amyloid formation, the question then arises as to which process occurs first: the formation of amyloids, which have toxic effects on neurons and disturb all types of metabolism, including energy thus resulting in neurodegeneration; or formation of amyloids in response to chronic glucose hypometabolism which serve as a beacon, signaling disturbances in energy metabolism that trigger neuronal and cognitive dysfunction [ ]. however, based on the assumption that the disruption of glucose utilization in the brain is a primary cause of neurodegeneration, it is expected that app up-regulation and accelerated aβ formation and accumulation should occur irrespective of age or cause of glucose deficiency. taking the predominant amyloid cascade hypothesis into account, this assumption is at least a little controversial, but it is confirmed by a huge body of evidence showing that app overexpression, leading to intensive aβ production, is observed in multiple pathologies associated with the breakdown of energy metabolism in the brains both in humans and animals. thus, enhanced amyloid formation and accumulation occurs in the brains of people of different ages during: hypoxia [ ], human and animal head trauma [ , ], spinal cоrd injury [ , ], neurоinflammatiоn [ , ], middle cerebral artery оcclusion [ ], general anesthesia [ ], influence of bacterial agents [ , ] and other examples [ ]. in fact, analysis of the above pathologies leads directly to the conclusion that there is steady damage of brain cells resulting from a number of different causes. for example, anesthesia can significantly disturb hemodynamics, reducing the brain’s oxygen and glucose absorption rate [ ] thereby leading to severe hypoxia, a sharp inhibition of aerobic oxidation and neuronal activity [ ]. interestingly, increased app processing and amylоid formation occur in the brain a few hours after administering isoflurane as an anesthetic [ ]. attenuated intake of glucose and oxygen to the brain together with the oxidative stress observed in ischemia-reperfusion also initiates app processing and amyloid formation in damaged brain structures [ ]. hypoglycemia-limited brain glucose intake and also promote amyloid accumulation [ ]. taken together, these data confirm that aβ peptides could accumulate in the brain any time when brain cells are destroyed due to a paucity of energy resources [ , ]. some scientists therefore believe that the initial aβ formation can be considered an adaptive reaction [ , ], protecting neurons against further damage [ ]. if this hypothesis is true, we must accept that the formation of amyloid plaques in the ad brain is not the start of a suicide program, but rather a signal indicating a disruption of brain metabolism and maybe even not the beginning, but the continuation of pathological process that may have gone unnoticed for several years at least [ ]. thus, unveiling the mechanisms of glucose metabolism disruption that underlie app up-regulation in the sporadic form of ad is a task of current concern in medicine and biology as a precursor to identifying risk factors for disease development and detecting new, alternative targets (other than amyloids) for therapeutic effect. . the possible role of erythrocytes in neuronal aerobic glucose metabolism crisis in ad: the erythrocytic hypothesis erythrocytes are the only cells able to carry oxygen and maintain aerobic utilization of glucose in tissue. in fact, many people are already well informed about red blood cells in a simplified way, j. clin. med. , , of viewing them only as small bags filled with hemoglobin that binds oxygen reversibly. notably, a remarkable series of studies has previously demonstrated a pivotal relationship between rbc metabolism and binding, transport, and delivery of oxygen to tissues. curiously, the first reports about this relationship were published more than years ago [ ] suggesting that these scientific findings are largely ignored. as a consequence, there is limited information regarding the interactions between metabolism and erythrocyte function. traditionally, red blood cell indices, hemoglobin quantities, hematocrit test, sedimentation rate, average volume, and morphological changes etcetera are used to diagnose different diseases, but it is unknown how changes outside the normal range in the above-measured parameters affect rbcs’ ability to deliver oxygen to tissues. it follows then that there is no tool for diagnosing metabolic illness in rbcs themselves, a disorder that may appear influenced by pathological factors present in circulation [ ]. passing through the lungs, rbcs are exposed to oxidative stress, in the kidneys which are characterized by hypertonic condition, the cells are the target of osmotic shock. to get through tight capillaries, erythrocytes experience significant mechanical compression, having to pass through capillaries with diameters smaller than their own [ ]. it has been proven that cells with impaired intracellular energy metabolism are unable to withstand such exogenous attacks, becoming damaged and lysed directly into the bloodstream as evidenced by the permanent presence of cell-free plasma hemoglobin [ ]. another consequence of erythrocyte “disorder” is an increase in oxygen affinity to hemoglobin, leading to the tissue hypoxia [ ] and, in particular, cerebral hypoxia. in order tоfulfil their function, rbcs should be healthy which depends primarily on their metabolic and antioxidant status contributing to adequate oxygen binding capacity. for this, all metabolic pathways in mature erythrocytes should be strictly regulated and proceed at the rate necessary to maintain their viability and functional activity. one of these processes is anaerobic glycolysis, the only source of atp production. pentose phosphate shunt is necessary for nadph formation, used in combined enzymatic reactions that catalyze glutathione reductase and glutathione peroxidase. these enzymes are antioxidant and responsible for maintaining low levels of hydrogen peroxide and therefore preventing methemoglobin formation. erythrocytes also need sufficiently high activity of other antioxidant enzymes such as superoxide dismutase, which maintains a safe level of superoxide radical (o •−), glutathione transferase, which is involved in xenobiotic detoxification [ ], catalase and peroxiredoxin- -peroxidase, which destroy hydrogen peroxide. red blood cells are not able to synthesize atp de novo, and energy homeostasis is maintained during high energy demand due to salvage pathways by which already existing nucleosides and purine bases can be recycled to produce adenine nucleotide triphosphates [ ]. for the production of , -diphosphoglycerate ( , -dpg), the main metabolite that facilitates the release of oxygen from hemoglobin to tissue [ ], and to maintain its steady state concentration, erythrocytes possess a unique glycolytic bypass called a rapoport–luebering shunt [ ]. the activity of this pathway depends on the rate of glycolysis and a relative deficiency of enzymes catalyzing the initial reactions of glycolysis may cause insufficient synthesis of , -dpg and affect the ability of rbc to release oxygen, leading to tissue hypoxia [ ]. therefore, intact intracellular metabolic pathways of erythrocytes are undoubtedly a major factor responsible for adequate oxygen delivery and release to tissues. we have recently demonstrated differences in the parameters of various metabolic pathways in erythrocytes of patients with alzheimer’s disease (ad group) and patients with non-alzheimer’s dementia (na group). we found that in erythrocytes of elderly control subjects (amc, age-matched controls), glycolysis and cation transport were sharply inhibited, as evidenced by a significant decrease in all glycolytic enzyme activities, a decrease in the rate of glucose consumption, atp concentration, the rate of pyruvate and lactate formation, and a sharp decrease in na+, k+-atp-ase activity compared to young adult controls (yac). in the erythrocytes of ad and na patients, these parameters changed to the same extent and significantly exceeded the parameters not only of amc, but also of the yac group indicating an increase in ion fluxes leading to acceleration of rbc glycolytic pathway [ , ]. j. clin. med. , , of given that the active transport of cations through the erythrocyte membrane is controlled by the rate of atp formation during glycolysis, up-regulation of na+, k+-atp-ase accompanied by a decrease in the concentration of atp in rbcs of ad patients can be attributed to an imbalance between atp formation and ion pumping, caused by increases in na+ input in erythrocytes of ad patients [ ]. despite glycolysis activation, this imbalance ultimately promotes an increase in adenylate catabolism as confirmed by adp and amp accumulation, a decrease in the cellular energy charge and the total content of adenine nucleotides. the enzyme activity of the rapoport–luebering shunt, in particular, diphosphoglycerate phosphatase (dpgp-ase), that regulated the steady state levels of , -dpg, increased simultaneously with a significant decrease in , -dpg concentration in erythrocytes of the ad group compared to both age-matched controls (amc) and young adult controls (yc). clearly, the affinity of hemoglobin for oxygen is influenced not only by , -dpg, but most likely by other factors such as ph level, pco , po , cl−, conformations of hemoglobin and temperature. however, the correlation between the concentration of , -dpg in erythrocytes and the degree of hypoxia in tissues, and particularly in the brain, has been revealed in many pathological states of human beings and animals [ – ]. taken together, the results obtained suggest that chronic intensification in the rate of cationic traffic and plasma membrane permeability observed in the rbcs of ad patients, could trigger a cascade of pathological reactions in erythrocytes. this then leads to accelerated hydrolysis of atp and , -dpg, responsible for regulating the affinity of hemoglobin for oxygen, one possible explanation for inadequate oxygen supply to the brain, glucose hypometabolism, and cognitive abnormalities in ad. we have also found that changes in many metabolic pathways are already present in the erythrocytes of healthy individuals entering old age but without memory problems. thus, the cells of the amc group were marked by disturbed homeostasis of adenine nucleotides, a slight but significant decrease in , -dpg concentration [ ]. similarly, there were no differences in pro-oxidant levels [ ] between amc, ad, and na groups, while antioxidant enzyme activity, considerably reduced in rbcs of the amc subjects, further decreased with dementia [ ]. our findings are largely consistent with data from other researchers who show the same direction of disturbances in erythrocytes of normal elderly people and patients with ad [ ]. they also indicate that the disturbed metabolism and reduced antioxidant capacity in rbcs are not hallmarks of the terminal illness, but are indicative of stable and permanent changes in intracellular metabolism in erythrocytes of the elderly, which under the influence of unknown factors may lead to the pathological lesions encountered in ad patients. one factor very likely to contribute to altered intracellular metabolic pathways and rbc morphology in older people is enhanced entry of na+ into the cells [ ]. it is clear, therefore, that increased activity of na+, k+-atp-ase in the erythrocytes of ad patients can be considered an adaptive reaction to the increased entry of this cation into cells. at the same time, in chronic conditions, constant and multiple activation of the enzyme cannot completely compensate for the increased plasma membrane permeability that leads to pathological consequences which negatively influence rbcs’ energy metabolism and antioxidant defence system, enhancing the hydrolysis of atp, , -dpg, oxidative stress and proteolysis. the combined effect of this damage disrupts the function of erythrocytes associated with oxygen delivery, and also causes changes in the morphological property of erythrocytes, decreasing their ability to deform and thus lowering the threshold for development of neuropathology. our erythrocytic hypothesis is thus based on the obvious link between the state of intracellular metabolism of erythrocytes and its functional ability. we suggest that abnormalities in glycolytic, antioxidant and transport pathways can disrupt the erythrocyte function associated with oxygen delivery to the brain and cause disruption of the aerobic oxidation of glucose, leading to degeneration of the nerve cells and impaired cognitive function as observed in ad. it is obviously necessary to elucidate what factors (endogenous and exogenous) cause the premature decrease in the reserve potential of erythrocytes to withstand stress that they constantly undergo, while circulating from the lungs to the tissues. j. clin. med. , , of . encapsulation of missing enzymes in erythrocytes: a way to reconstruct energy metabolism erythrocytes are known as cells that can be loaded with different kinds of substances (drugs, enzymes, metabolites, cofactors, etc.) through methods based on the hypotonic hemolysis-resealing procedure that allows to design intact and fully viable erythrocytes [ , ]. based on the above methodоlogy we developed a procedure for encapsulating missing enzymes together with the substrates and cofactors involved in the energy metabolism and antioxidant defense system. our findings show that after reinjection into rat blood, enzyme-loaded erythrocytes were able to retain their integrity, normal energy metabolism, and survive in blood circulation for a long time [ ]. this biotechnological approach provides an extraordinary opportunity to develop innovative medications for individual use that will help specifically to treat the endogenous metabolic abnormalities in the red blood cells and restore adequate oxygen supply to the brain. . conclusions more than years have passed since alzheimer’s disease was identified, yet the pathogenesis of the disease remains unknown. taking into account the role of the vascular hypothesis in ad pathogenesis, we assume that among the additional causes of pathological brain hypoperfusion typical in ad are structural and biochemical changes in erythrocytes, leading to inadequate oxygen supply to the brain, which inevitably precedes brain atrophy, developmental disabilities and dementia. therefore, change in biochemical parameters in erythrocytes can be considered both an indicator of the cell state in the central nervous system, and a new target to develop innovative methods to treat this systemic disease. the question of whether cerebral vascular damage or rbc damage is the most important cause of cerebral hypoxia is beyond the scope of this study. it is needless to say that both pathologies are intrinsically closely related to each other. however, since erythrocytes serve as the only oxygen carriers and their ability to bind, transport and deliver oxygen to tissues depends, primarily, on energy metabolism and antioxidant systems, we believe that disturbance of the endogenous processes in these cells most likely has a dramatic destabilizing impact on aerobic glucose metabolism in the brain and promotes dementia development. this assumption does not contradict the known pathological consequences of vascular damage, that leads to impaired blood circulation and brain hypoperfusion. at the same time, it clearly indicates the possible existence of additional unspecified mechanisms, restricting oxygen supply to the brain and therefore participating in the development of hypoxia and neurodegenerative processes specific to ad. we therefore suggest that a combination of revascularization and restoration of metabolism in erythrocytes which maintain glucose/oxygen-dependent normal neuronal function could prevent brain cells from the destructive effects of energy limitation and hypoxia, and avoid dementia development. a thorough and detailed study of erythrocyte metabolism and morphology is needed not only to identify potential risk factors, but also to shed light on the molecular mechanisms that limit oxygen supply to the brain. this knowledge is important to prevent the development of hypoxia-induced neurodegenerative processes typical not only of ad, but also of many other diseases with different etiologies, and characterized by varying degrees of cognitive dysfunctions. author contributions: e.k., l.t., c.m. provided the original conception and designed the study; e.k., l.t., a.u., g.a. analysed data and discussed the results. the manuscript was written by e.k. and approved by all the authors. all authors have read and agreed to the published version of the manuscript. funding: the study reported was funded by rfbr through the research project no - - and ministerio de ciencia e innovación-instituto de salud carlos iii (fis pi / ) co-funded with european regional development funds (erdf) and fundación ramón areces. conflicts of interest: the authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. j. clin. med. , , of references . miklossy, j.; taddei, k.; martins, r.; escher, g.; kraftsik, r.; pillevuit, o.; lepori, d.; campiche, m. alzheimer disease: curly 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[crossref] . deloach, j.r.; sprandel, u.; green, r. carrier erythrocytes: a prospectus for the future. bibl. haematol. , , – . © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . / http://dx.doi.org/ . /ad. . http://dx.doi.org/ . / http://www.ncbi.nlm.nih.gov/pubmed/ http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /s - - - http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /pnas. . . http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /j. - . . .x http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /bf http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	introduction 	evidence that contradicts the fundamental principles of the amyloid cascade hypothesis 	brain amyloid plaques and soluble a oligomers are unspecific for ad 	a neurotoxicity: which peptide is a therapeutic target 	can transgenic rodents be used as a suitable model for sporadic ad 	brain energy crisis and a accumulation: cause or consequence 	the possible role of erythrocytes in neuronal aerobic glucose metabolism crisis in ad: the erythrocytic hypothesis 	encapsulation of missing enzymes in erythrocytes: a way to reconstruct energy metabolism 	conclusions 	references preparation, formation mechanism, photocatalytic, cytotoxicity and antioxidant activity of sodium niobate nanocubes research article preparation, formation mechanism, photocatalytic, cytotoxicity and antioxidant activity of sodium niobate nanocubes muhammad nawazid *, sarah ameen almofty , faiza qureshi , department of nano-medicine research, institute for research and medical consultations (irmc), imam abdulrahman bin faisal university, dammam, saudi arabia, department of stem cell research, institute for research and medical consultations (irmc), imam abdulrahman bin faisal university, dammam, saudi arabia, deanship of scientific research, imam abdulrahman bin faisal university, dammam, saudi arabia * mnnmuhammad@iau.edu.sa, nawwaz@gmail.com abstract a hydrothermal method was employed to prepare the sodium niobate (nanbo ) nano- cubes. we executed time dependent experiments to illustrate the formation mechanism of sodium niobate nanocubes. it was observed that the morphology of nanbo nanocubes was dependent on the reaction time and hr reaction time was found to be suitable. mor- phology, composition, structure and optical properties of sodium niobate nanocubes were evaluated by scanning electron microscope, x-ray energy-dispersive spectrometer, x-ray diffraction and uv-visible diffuse reflectance spectrometer. the photocatalytic activity of sodium niobate was studied for photocatalytic hydrogen production. it was anticipated that the sodium niobate (nanbo ) cubes exhibited good photocatalytic activity under uv light irradiation using lactic acid as sacrificial agent. the cytotoxicity activity of sodium niobate nanocubes was studied as well at different concentrations ( mg/ml, mg/ml, mg/ml, and . mg/ml) against human colon colorectal carcinoma cell line (hct ) by mtt assay and ec was found to be . mg/ml. sodium niobate proved to be a good dpph free radical scavenging material, tested at different concentrations. it was noticed that peak intensity at nm was decreased after minute incubation, further supporting the antioxi- dant activity. this study will be useful for design and engineering of materials that can be used in biomedical applications and in photocatalysis. introduction excess consumption of fossil fuel and increased pollution has make scientists actively looking for solutions in terms of energy and environmental issues. hydrogen is as an eco-friendly fuel and an alternative source of energy. currently, hydrogen is mostly used as energy source via fossil fuels and electrolysis of water, the use of latter, however is economically not feasible as the process consumes high energy. solar energy is the alternatively favored renewable energy source that can satisfy the global energy requirements. in order to resolve energy crisis and environmental problems, photocatalytic hydrogen evolution using photocatalysts of plos one | https://doi.org/ . /journal.pone. september , / a a a a a open access citation: nawaz m, almofty sa, qureshi f ( ) preparation, formation mechanism, photocatalytic, cytotoxicity and antioxidant activity of sodium niobate nanocubes. plos one ( ): e . https://doi.org/ . /journal.pone. editor: yogendra kumar mishra, institute of materials science, germany received: june , accepted: august , published: september , copyright: © nawaz et al. this is an open access article distributed under the terms of the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. data availability statement: all relevant data are within the paper. funding: the authors would like to thank king abdulaziz city for science and technology (kacst) for financial support of this work through project number - - مص . competing interests: the authors have declared that no competing interests exist. http://orcid.org/ - - - https://doi.org/ . /journal.pone. http://crossmark.crossref.org/dialog/?doi= . /journal.pone. &domain=pdf&date_stamp= - - http://crossmark.crossref.org/dialog/?doi= . /journal.pone. &domain=pdf&date_stamp= - - http://crossmark.crossref.org/dialog/?doi= . /journal.pone. &domain=pdf&date_stamp= - - http://crossmark.crossref.org/dialog/?doi= . /journal.pone. &domain=pdf&date_stamp= - - http://crossmark.crossref.org/dialog/?doi= . /journal.pone. &domain=pdf&date_stamp= - - http://crossmark.crossref.org/dialog/?doi= . /journal.pone. &domain=pdf&date_stamp= - - https://doi.org/ . /journal.pone. http://creativecommons.org/licenses/by/ . / semiconductors such as oxides, sulfides and nitrides has been considered as an attractive and clean way, low-cost and eco-friendly production of hydrogen [ – ]. the engineering and design of nanomaterials with controlled morphology has been getting more attention and significance owing to their unique physical and chemical properties. the photocatalytic properties of nanomaterials are vastly dependent on shape, size, crystal facets, size distribution and phases [ – ] which makes it much more challenging for the researchers to prepare the perfectly engineered materials that can be used as biomaterial, photocatalyst, catalyst support and adsorbent [ – ]. sodium niobate (nanbo ) is a fascinating material with pervoskite structure at a low cost. it has high crystallinity and good chemical stability with low environmental impact [ – ], attracts scientists due to its ionic conductivity, photorefractive properties, nonlinear optics and photocatalytic properties [ – ]. different morphologies of nano nanbo , such as nano- plates, nanocubes and nanowires have been studied for photocatalytic activities with the con- clusion that photocatalytic activity improved with controlled morphology of nanbo [ – ]. current research indicates that sodium niobate is an efficient photocatalyst for hydrogen pro- duction [ ], photocatalytic decomposition of organic contaminants [ ] and co reduction [ – ]. several methods had been reported for the preparation of sodium niobate (nanbo ), how- ever, most of them involved complicated polymerized complex methods [ , ], and there- fore, the need to develop simple and economic method for the preparation of sodium niobate (nanbo ) was felt. as we discussed above, to resolve the energy crisis there is need to prepare the low-cost and eco-friendly photocatalyst for hydrogen production. this study involved the preparation of sodium niobate (nanbo ) by hydrothermal method and its application as photocatalyst and biomaterial. furthermore, the formation mechanism and cytotoxicity of sodium niobate has never been explored and studied so far. this study is useful to provide the details of formation mechanism of nanbo and to study the cytotoxicity, antioxidant and photocatalytic activity. materials and methods chemical and materials all chemicals, kits and reagents were purchased from commercial sources and used as it. preparation of sodium niobate cubes a mixture of niobium pentoxide (nb o , . g) and sodium hydroxide ( . g), was stirred in deionized water at room temperature for certain period. the solution was then transferred into teflon-lined autoclave and heated at ˚c for h. after cooling, teflon-lined autoclave at room temperature; the white precipitates obtained were centrifuged and washed several times with deionized water and ethanol. lastly, the product was dried at ˚c for h. characterization x-ray diffraction pattern of nanbo was recorded on a rigaku x-ray diffractometer using cu kα radiation. morphology of the product was observed by field emission scanning electron microscope (fe-sem) and elemental composition was determined by x-ray energy-dispersive (edx). the uv-visible spectrum was obtained on shimadzu uv-vis spectrophotometer using baso as a reference. sodium niobate nanocubes for photocatalytic and biomedical applications plos one | https://doi.org/ . /journal.pone. september , / https://doi.org/ . /journal.pone. photocatalytic activity photocatalytic activity of nanbo was studied in a closed gas circulation system under a w xenon lamp. mg of catalyst was added to aqueous lactic acid solution and dispersed ultrasonically. the solution was evacuated for – minutes to remove the dissolved gases before irradiation and then exposed to irradiation by xe lamp. the hydrogen gas generated was determined in situ by a gas chromatogram (techcomp, gc -ii) equipped with a tcd detector [ ]. cell culture and cytotoxicity activity human colon colorectal carcinoma cell line (hct ) was purchased from attc (american type culture collection, usa) and maintained in dmem medium. cytotoxicity activity of nanbo nanocubes were evaluated against hct cells by mtt assay vybrant mtt cell proliferation kit (thermo fisher scientific). hct cells were seeded in -well plates at ( cells/well) in dmem medium supplied with % fetal bovine serum and % penicillin- streptomycin. different concentrations of nanbo nanocubes ( mg/ml, mg/ml, mg/ml, and . mg/ml) were added to the wells. cells were maintained in humidified atmosphere with % co at ˚c and incubated for h. after incubation, culture medium was removed and fresh medium was added with μl of mtt solution, cells were further incubated for h at ˚c. medium was removed after incubation and sterile dmso ( μl) was added to solu- bilize the formazan blue crystals. synergy neo multi-mode microplate reader (biotek) was employed to record the absorbance at nm. cell viability was then calculated using follow- ing formula: cell viability ð%Þ¼ absorbance of sample=absorbance of control � antioxidant activity the antioxidant activity of nanbo was studied using dpph as free radicals source. to assess the antioxidant activity of nanbo , different concentration such as mg/ml, mg/ml and mg/ml were prepared. ml of dpph solution ( . mm in methanol) was mixed with ml of nanbo different concentrations and incubated in dark for minutes. mixture was centri- fuged and supernatant was analyzed at nm against blank using uv-visible spectrophotom- eter. the % inhibition of dpph scavenging activity was computed as: % dpph radical scavenging activity ¼ðabsblank � abssample=absblankÞ� where abs blank is the absorbance of blank and abs sample absorbance of sample. results & discussion characterization nanbo nanocubes were prepared by hydrothermal method and morphology of the product was observed by sem. fig a shows representative images of nanbo nanocubes at different magnifications. it is clear from sem images that the product has nanocubes morphology with nm in size. the crystal structure of nanbo was probed by x-ray diffraction. fig b shows the xrd pattern of nanbo prepared at ˚c for h. the sharp and strong diffraction peaks suggest a nanocrystalline structure. all the diffraction peaks can be indexed as cubic phase of nanbo sodium niobate nanocubes for photocatalytic and biomedical applications plos one | https://doi.org/ . /journal.pone. september , / https://doi.org/ . /journal.pone. (jcpds card no. – ). no impurities can be detected in this pattern, which implies cubic phase of nanbo can be obtained under the described experimental conditions. energy-dispersive x-ray spectroscopy (edx) was performed to confirm the composition of the as-prepared product. we selected different surface as collection areas and found the same results. fig c shows energy-dispersive x-ray spectroscopy (edx) spectra of nanbo ; con- firming the presence of na, nb and o in the product and also shows there is no impurity in the product. a uv-visible diffuse reflectance (drs) spectrum of nanbo is revealed in fig d. the diffuse reflectance spectra of the product demonstrated an absorption edge at nm in the uv region, corresponding to the band gap energy of . ev. formation mechanism in order to check the effect of different solvents on the morphology and size of nanbo , experiments were conducted in water, methanol and ethanol at ˚c. sem results obtained fig . characterization data of nanbo . (a) fesem images of nanbo . (b) xrd pattern of nanbo . (c) edx pattern of nanbo . (d) dr-uv- visible spectrum of nanbo . https://doi.org/ . /journal.pone. .g sodium niobate nanocubes for photocatalytic and biomedical applications plos one | https://doi.org/ . /journal.pone. september , / https://doi.org/ . /journal.pone. .g https://doi.org/ . /journal.pone. in different solvents are shown in fig a– c. as we can see in the fig a, when reaction was conducted in the water, the product was nanocubes. on the other hand, when reaction was performed in methanol and ethanol, nanocubes were not formed (fig b and c). hence water was selected as a reaction medium for the preparation of nanbo nanocubes. to optimize the reaction temperature and to see the effect of temperature on the morphology and size of nanbo nanocubes, we performed the reaction at different temperatures ( ˚c, ˚c and ˚c). sem images of the products obtained at ˚c, ˚c and ˚c are shown in the fig a– c. it is clear from sem results, the product obtained at ˚c has big block like morphol- ogy with aggregates (fig a). on the other hand, when reaction was performed at ˚c, nanorods and aggregated nanocubes were formed (fig b). furthermore, the product obtained at ˚c was consisted of nanocubes (fig c). these results suggested that reaction tempera- ture ˚c is optimal to get nanbo nanocubes. to further understand the formation mecha- nism of nanbo nanocubes at ˚c, we conducted reactions at different times. as it is evident from fig a, the product obtained after minute of reaction comprises of spheres. after h, nanocubes are formed with the co-existence of small particles (fig b). the sem image in fig c indicates that nanocubes are formed as the reaction proceeded for h. fig d is sem image of nanocubes formed after h reaction time with some aggregates. finally, well- developed nanocubes (having size from – nm) were observed upon increasing further reaction time to h (fig e). fig . effect of solvents on the morphology and size of nanbo . (a) water. (b) methanol. (c) ethanol. https://doi.org/ . /journal.pone. .g fig . effect of temperature on the morphology and size of nanbo . (a) ˚c. (b) ˚c. (c) ˚c. https://doi.org/ . /journal.pone. .g sodium niobate nanocubes for photocatalytic and biomedical applications plos one | https://doi.org/ . /journal.pone. september , / https://doi.org/ . /journal.pone. .g https://doi.org/ . /journal.pone. .g https://doi.org/ . /journal.pone. fig . fesem images of nanbo at different times. (a) min. (b) h. (c) h. (d) h. (e) h at ˚c. https://doi.org/ . /journal.pone. .g sodium niobate nanocubes for photocatalytic and biomedical applications plos one | https://doi.org/ . /journal.pone. september , / https://doi.org/ . /journal.pone. .g https://doi.org/ . /journal.pone. based on the above discussion, it can be deduced that oriented attachment and ostwald rip- ening are involved for the formation of nanbo nanocubes. fig displays proposed formation mechanism for nanbo nanocubes. in the course of reaction, naoh reacts with nb o and it results in the formation of primary nanocrystals. the primary nanocrystals undergo oriented attachment to form small cubes. these primary nanocubes undergo mutual orientation and self-assembled to form nanocubes (fig ). when reaction was preceded further, reaction rate further decreased and at this stage ostwald ripening became more dominant. due to higher surface energy, small particles slowly dissolved to form nanocubes [ ]. stepwise formation mechanism is illustrated in fig . photocatalytic activity the photocatalytic activity of synthesized nanbo nanocubes for hydrogen production was evaluated under uv light and expressed in terms of hydrogen evolution rate (fig ). as it can be seen in fig , the photocatalytic activity of nanbo started increasing with passage of time. however, after certain time the photocatalytic activity was dramatically decreased. it could be possible that with the lapse of time the concentration of sacrificial reagent was decreased which result in the lower rate of hydrogen production. the photocatalytic activity of nanbo could be ascribed to its light harvesting ability and can accelerate the transportation of photo- generated electron hole pairs, making the photocatalytic process more efficient [ ]. further- more, good crystallinity of nanbo also reduces the chance of electron hole recombination and enhances the photocatalytic activity. proposed mechanism for the photocatalytic hydrogen production of nanbo under uv light irradiation is illustrated in fig . cytotoxicity activity the cytotoxicity activity of nanbo nanocubes was studied against human colon colorectal carcinoma cell line (hct ) at different concentrations such as mg/ml, mg/ml and mg/ml and . mg/ml. the cytotoxicity activity of nanbo nanocubes was observed from mg/ml concentration and at the higher concentrations, whereas no detectable effect at the fig . stepwise illustration for the formation mechanism of nanbo nanocubes. https://doi.org/ . /journal.pone. .g sodium niobate nanocubes for photocatalytic and biomedical applications plos one | https://doi.org/ . /journal.pone. september , / https://doi.org/ . /journal.pone. .g https://doi.org/ . /journal.pone. lowest concentration ( . mg/ml) was observed. the effective concentration (ec ) of nanbo was calculated using the equation generated from exponential chart of the cell viabil- ity percentage against concentrations. ec was found . mg/ml. the cell viability % of the nanbo nanocubes treated cells at different concentration is shown in fig . antioxidant activity we considered different concentration of nanbo nanocubes to study the antioxidant activ- ity. during the experiment, a change in color of dpph solution from violet to pale yellow was noticed in the presence of nanbo nanocubes. furthermore, intensity of peak at was decreased after minute (fig ), indicated the free radical scavenging activity of nanbo nanocubes. the free radical scavenging activity of nanbo was perceived between . to . % at different concentrations. the decline in intensity of peak at nm could be attrib- uted due to the transfer of electron density situated at oxygen to the odd electron found at nitrogen atom in dpph. the results of this study were promising; sodium niobate (nanbo ) with controlled mor- phology (nanocubes) was prepared at ˚c. nanbo revealed good photocatalytic activity fig . h evolution rate by nanbo for h irradiation. https://doi.org/ . /journal.pone. .g sodium niobate nanocubes for photocatalytic and biomedical applications plos one | https://doi.org/ . /journal.pone. september , / https://doi.org/ . /journal.pone. .g https://doi.org/ . /journal.pone. for hydrogen production by splitting water indicating that it can be used as photocatalyst. the effective concentration (ec ) of nanbo nanocubes against human colon colorectal carci- noma cell line (hct ) was observed . mg/ml. nanbo also demonstrated good antioxi- dant activity at different concentrations. biological results indicate that nanbo can be used as biomaterial. conclusion nanbo nanocubes were successfully produced via facile hydrothermal method. time depen- dent study was conducted to deduce the formation mechanism of nanbo nanocubes. results revealed development of nuclei that transitioned to segregated nanocubes as the reaction time progressed. band gap of nanbo was observed . ev and it exhibited good photocatalytic activity for hydrogen production under uv light irradiation. ec of nanbo nanocubes against human colon colorectal carcinoma cell line (hct ) was found to be . mg/ml. the antioxidant activity was found to be significant too and coupled with anticancer potential can be a good candidate as an engineered biomaterial. this work provides insights for the fig . proposed mechanism for the photocatalytic hydrogen production of nanbo under uv light irradiation using lactic acid as sacrificial agent. https://doi.org/ . /journal.pone. .g sodium niobate nanocubes for photocatalytic and biomedical applications plos one | https://doi.org/ . /journal.pone. september , / https://doi.org/ . /journal.pone. .g https://doi.org/ . /journal.pone. fig . percentage of cell viability using mtt assay. hct cells were treated with different concentrations of nanbo nanocubes ( mg/ml, mg/ml, mg/ml and . mg/ml) and mtt assay was performed h post incubation to measure the cell viability. the statistical analysis was performed using oneway anova- dunnett’s test, whereas � = p< . . https://doi.org/ . /journal.pone. .g sodium niobate nanocubes for photocatalytic and biomedical applications plos one | https://doi.org/ . /journal.pone. september , / https://doi.org/ . /journal.pone. .g https://doi.org/ . /journal.pone. preparation of nanbo nanocubes with well-regulated morphologies, serving as promising photocatalyst. acknowledgments the authors would like to thank king abdulaziz city for science and technology (kacst) for financial support of this work through project number: - - مص . author contributions conceptualization: muhammad nawaz. investigation: sarah ameen almofty, faiza qureshi. references . sim u, yang t.-y, moon j, an j, hwang j, seo j.-h, et al. 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, volume- , issue- s , september published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s  abstract—this paper deals with the implementation of providing an uninterrupted supply of bldc motor using pv array and utility grid. here we have proposed a system where brushless dc motor (used for water pumping) is driven constantly using solar photovoltaic (pv) and the power grid. the solar panels providing energy is used as the main power source, thus helping reduce the load over the power grid. the grid is used as secondary or backup source to run the motor in case solar panel fails to provide sufficienct energy. the proposed system helps to supply continuous amount of power to the motor which can be used for irrigation. the energy from the solar panel is used to store energy in the battery which in turn is used to run the motor.a simulation of the proposed system is carried out to demonstrate the applicability of the system. keywords: photovoltaic panel, dc-dc converter, simulink, voltage source inverter, pmdc motor i. introduction as the world evolves, we are getting surrounded by numerous new electrical and electronic gadgets, which requires a high amount of power and increases overall load on the power grid. the majority of power in india is generated by non-renewable energy resources, which has increased level of pollution exponentially[ ]. this calls for reducing our usage of such resources and switch to renewable energy sources.[ ] solar backed power system finds its best uses in rural areas since some of these areas are isolated from the power grid. india's % population resides in rural areas. and the majority of them are involved in the agriculture sector. the only major requirement in farming is the constant supply of electricity for irrigation purposes. but some villages either get a limited amount of constant electricity or are isolated from the main power grid. the solar backed power system finds its best use in this type of scenario. in our proposed system we have used the solar panel as our primary source and added a lead-acid battery to store the energy from the panel. a dc-dc boost converter[ - ] is used to level up the voltage of pv panel and charge the battery. we have used power grid[ , ]as a backup supply. a vsi[ ] is used to run the bldc motor. thus providing a continuous supply for irrigation purposes. using bldc motor [ - ] for irrigation revised version manuscript received on , september . d. sattianadan, srm institute of science and technology, kattankulathur, chennai, tamil nadu, india. hemrajsinhparmar, srm institute of science and technology, kattankulathur, chennai, tamil nadu, india. tushar bhatt, srm institute of science and technology, kattankulathur, chennai, tamil nadu, india. vineet kumar, srm institute of science and technology, kattankulathur, chennai, tamil nadu, india. george fernandez.s, ,srm institute of science and technology, kattankulathur, chennai, tamil nadu, india. [ ] and water pumping proposes is more reliable and economically efficient as compared to other motors. solar cell a sunlight based photovoltaic or sun powered cell is a gadget that utilizes the photoelectric impact to changes over light into electric flow. it is made of silicon molecules. as the structure of silicon cell varies, we can utilize its basic property to generate electricity. at the point when a photon with enough energy to break the bond of silicon molecules fall over it, it liberates the electrons as the bonds between them is broken and it leaves their position and now is charged to move and can consume the available space. these free electrons are called free carriers, which can move freely around the crystalline cross section. on adding impurities, for example, phosphorous, boron molecules, it takes the very least amount of energy to knock out one free electron.in this way we can have a lot of free carriers as compared to pure silicon. to make a solar cell we have two types of silicon layer. one which is highly doped with phosphorous (n type) and the other is boron(p type). when these layers come in contact with each other they form a junction. now no electron can cross this junction on its own. when a photon strikes the cell the energy of photon is transferred to the atom, which is sufficient enough to knock of one electron from p layer pass through the barrier and reach n layer. now this electron can flow around the circuit by attaching a metallic wire to both the layers. this is the way how a solar cell works. advantages of solar cell  no noise pollution.  no need for operational maintenance.  does not contains any moving parts. fig. solar cell uninterrupted supply to bldc motor using pv and grid d. sattianadan, hemrajsinh parmar, tushar bhatt, vineet kumar,george fernandez.s uninterrupted supply to bldc motor using pv and grid published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s solar panel a solar module consists of various solar cells electrically connected in series to achieve more voltage or in parallel to get maximum current. a solar panel is a combination of various solar modules. a box is fitted behind the panel to get the output from the panel. it is provided protection against the rough weather conditions such as rain, dust, sandstorm etc. the conductive wires which carry the current out from the panel to the circuit may have highly conductive metals eg. silver, copper. some solar panel set ups have large mirrors/reflectors to divert the sun rays directly to the panels resulting in a efficient operation of extracring the solar power. fig. solar cell to solar array boost– converter a boost converter comes in handy when the required voltage at the load end is not possible to get from the input source. it consist of an inductor, capacitor, switch and a diode. at first when the switch s as shown in the fig. . is closed, the inductor stores the current by forming a magnetic field. now when the switch is opened the charge collapes from the inductor quickely giving rise to voltage (∆v) and in addition to that the input voltage also addes up at the capacitor end, hence the resultant voltage is (∆v+v). this is how the input voltage is steped up. fig. boost power stage brushless dc motor as usual motors, brushless dc motor also has a rotor and stator. rotor of the motor is in the form of a permanent magnet, whereas the stator is similar to that of polyphase stator winding. as the name suggests brushless, no brushes are utilized and the commutation is done electrically, it is achieved by taking feedback of stator windings. the standards for the working of a bldc motor that it takes the position input of the interior shaft which is equivalent to that of the brushed dc motor. in the event of a brushed dc motor, mechanical commutator and brushes are utilized to get the position. though in bldc motor, it is accomplished by utilizing different input sensors. by and large, the hall impact sensor is utilized to get the situation of the rotor posts. at whatever point rotor attractive posts go close to the hall effect sensor, they create a high or low-level flag, through which the situation of the rotor shaft can be resolved. on the off chance that the bearing of the attractive field is turned around, the voltage created will invert as well. advantages of bldc motor  high efficiency  does not cause any noise while running  no fritional loss  can vary speed up to considerable range voltage source inverter the inverter is a device that converts a direct current (dc) into alternating current (ac). as the name suggests vsi converts a dc voltage into an ac voltage by keeping the voltage constant. it consist of one dc source, for switching we use a transistor, diodes connected to anti parallel with a transistor and a large capacitor. for our project we have used -phase vsi. we have used mosfet for switching purposes. fig. vsi pic controller pic (peripheral interface controller) has a place with the group of microcontrollers made by microchip innovation. prior pic microcontrollers used to have rom (read only memory) or field programmable eeprom for program storage. the ongoing models have streak memory for program storage likewise the program memory and information memory are isolated from one another. there are distinctive guidance sets for various models. pic gadgets are extremely mainstream among businesses and research, researchers because of their minimal effort, wide accessibility, sequential programming. international journal of recent technology and engineering (ijrte) issn: - , volume- , issue- s , september published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s for our proposed model we have utilized pic f a port a, port b, port c, port d and it has pins tx and rx for sequential correspondence. rx is for accepting information and tx is for transmitting information. it underpins spi convention also. sticks in port an are simple and port b likewise has sticks yet these pins are computerized pins. port c is additionally an advanced port same as that of port b. sticks in port c pins are utilized for sequential correspondence. port d has pins which are generally computerized pins. port e comprises just of pins. fig. pic f bridge rectifier a device that can give dc output voltage by using ac voltage is termed as a rectifier. bridge rectifier consist of four diodes connected in series in such a way that only two diodes conduct for half ac cycle and the other two for the other half cycle. a capacitor is required to reduce the amount of ripple in the output waveform. the ratio of output dc power to ac input power is defined as rectifier’s efficiency. fig. bridge rectifier battery a battery is a gadget that is comprised of at least two or more than two electrochemical cells which are associated in series or parallel with one another. this could be to give power to electrical appliances, for example, laptops, tv remotes, and e-bikes. it has two terminals positive and negative commonly known as cathode and anode respectively. it is commonly used to store the energy so that we can use it later when required. this is the reason we have taken a battery so as to store the energy generated by panel and can use dit to run motor when required. ii.circuit explanation as shown in the above fig. the main source as pv panel of v, w is taken to charge the battery of v, . ah. to boost the voltage, as the output voltage of the pv panel is low a boost converter is used. to reach the output voltage of v % of the duty cycle is used so as to keep the battery charging. now the voltage is given to vsi to govern the bldc motor as per the requirement. the duty cycle of the vsi inverter is controlled using a pic microcontroller. since the maximum output signal voltage generated by pic microcontroller is v and the voltage required to trigger the mosfet is v we need a gate driver circuit through which we can boost output signal voltage of pic microcontroller. to do so we have used monolithic high and low side gate driver ic (fan n). it can drive high-speed mosfet that operates up to v. in case the amount of radiation is not sufficient enough to provide the required voltage in order to run the motor we have a backup source as a power grid. uninterrupted supply to bldc motor using pv and grid published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s fig. circuit diagram whenever pv-battery system fails to run the motor we switch on to our backup source single phase grid supply. the single phase ac supply i.e. v is being stepped down to v by the step-down transformer. this v of ac supply is now converted into dc voltage using bridge rectifier. now, this v dc supply used to run the motor after passing it through vsi, which converts dc voltage to ac which is now being used to run the bldc motor. iii. simulation of the proposed model fig . shows the mat lab simulation circuit using which various observation and graphs have been studied, through which we can analyze whether or not the proposed system is effective and efficient for rural areas or not. fig. simulation circuit international journal of recent technology and engineering (ijrte) issn: - , volume- , issue- s , september published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s iv simulation results single phase grid voltage graph the input voltage is taken from the grid when solar pv array incapable of running the motor on its own. the voltage is of v which is given to rectifier so as to change the ac voltage into constant dc voltage. fig. single phase grid input voltage after rectifying voltage graph the v ac supply is being fed into the rectifier to convert it into constant dc supply which is used as the input source for the vsi converter. after rectifying the ac voltage the output constant voltage is of v(dc) as shown in fig . . fig. voltage after rectifying pv panel voltage during the day time when there is a sufficient amount of radiation the voltage we get is of v which in the ideal case is in dc. as the radiation is kept constant the output of the pv panel will be constant. fig. pv panel voltage voltage after boosting the pv panel voltage as the input for the vsi converter is around v we have boosted the voltage from the solar pv panel to v using boost converter. the duty cycle for boost converter is % so the output from boost converter is v. fig. output voltage of boost converter rotor speed graph fig. speed of the rotor v. hardware implementation components quantity step down transformer ( - v) capacitor ( µf), ( µf), ( µf) inductor ( µh) resistors ( Ω), ( Ω), ( Ω) mosfet (p nk fp) microcontroller (pic f ) diodes (in ) gate driver ic (fan ) bldc motor ( kv) pwm controller (ka a) uninterrupted supply to bldc motor using pv and grid published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s fig. hardware setup vi. conclusion looking at the current energy crisis, renewable energy resources plays an important role to fill the gap between generation and consumption of power. solar energy has emerged as one promising source of energy. it is predominant among the renewable energy resources. it can be used for irrigation purposes, driving water pumps in rural areas. many papers have reported on this topic and is currently under active area of research. a bldc motor drive fed water pump powered by solar energy is a solution to the energy crisis. the unreliability of pv power due to the weather conditions is resolved by using the power grid as a backup. the proposed system helps the consumer in rural areas to get continuous and reliable motor output required for irrigation irrespective of the weather conditions. references investigation and analysis on the combined operation of solar thermal power and conventional thermal power d. y. liu, j. wang, x. q. feng, s. guo, c. xu application of solar powered automatic water pumping in turkey. mahir dursun and semih ozden.international journal of computer and electrical engineering, vol. , no. , april study of boost type dc-dc converter for single solar cell.atsushi nakajima,shigeo masukawa department of electrical and electronic engineering ,tokyo denki university a photovoltaic panel emulator using a buck-boost dc/dc converter and a low cost micro-controller. dylan d.c. lu , quang ngoc nguyen chool of electrical and information engineering, the university of sydney, nsw , australia buck-boost converter fed bldc motor drive for solar pv array based water pumping. drive rajan kumarl and bhim singh imember, ieee, fellow, ieee , department of electrical engineering, indian institute of technology delhi, hauz khas, new delhi-l , india huang, “photovoltaic water pumping and residual electricity grid connected system,” chinese patent cn u, jan. , . design, simulation and implementation of a grid tied solar power controller integrated with instant power supply technology.masum billah, sanjoy kumar das, md. toriqul islam, md. anamul haque, bishwajit banik pathik. dept. of electrical and electronic engineering american international university-bangladesh (aiub), dhaka, bangladesh p. k. singh, b. singh and v. bist, “brushless dc motor drive with power factor regulation using landsman converter,” iet power electron., vol. , no. , pp. - , apr. . c. l. xia, permanent magnet brushless dc motor drives and controls. beijing, china: wiley, . implementation of a three phase inverter forbldc motor drive adnan mohammad, md. anwarul abedin, and md. ziaur rahman khan department of electrical and electronic engineering,bangladesh university of engineering and technology (buet) dhaka university of engineering and technology (duet) dhaka, bangladesh solar pv-battery based hybrid water pumping system using bldc motor drive rajan kumarl and bhim singh imember, ieee, fellow, ieee , department of electrical engineering, indian institute of technology delhi, hauz khas, new delhi-l , india pv power system based mppt z-source inverter to supply a sensorless bldc motor.s.a.kh. mozafari niapoor, student member ieee , s. danyali, m.b.b. sharifian faculty of electrical & computer engineering, university of tabriz, tabriz, iran. st power electronic & drive systems & technologies conference rajan kumar and bhim singh, "bldc motor-driven water pump fed by solar photovoltaic array using boost converter," annu. ieee india conf. (indicon), new delhi, . wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ renewable energy sector – solving the global problem of climate and environment change the impact on climate and environment change – renewable energy sector elena gurgu, lecturer ph.d. faculty of marketing and international affaires spiru haret university abstract most of the people have an idea of what renewable energy sources are and what they can offer us. the majority of people are also very aware of the impact that non-renewable energy is having on the environment. the adage reduce, reuse, recycle is commonly recited today by adults and children alike. we have started to see an increase in the reduction of waste and consumption of energy and the recycling and reuse of products we use. it is time to see an increase, however, in the use of renewable energy. key-words: environment, climate change, renewable energy, non- renewable energy, recycling, alternative energy sources jel classification: q , q , q , q introduction this article is about to put the accent on solving one of the biggest problems of the mankind – the climate and environment change. human beings require energy – and lots of it – to run our planet. every since the industrial revolution, we have required more and more energy each year to keep our factories, automobiles, air conditioning units, and domestic appliances running. as large nations like china continue to ramp up industrial production at record rates, the global demand for energy has never been greater. traditionally, industrial nations have relied upon fossil fuels like oil, coal and natural gas to power their economies. fossil fuels are an example of this type of energy resources. but the disadvantages of using this type of energy are multiple: a) contributes to the warming of the planet, or global warming; b) causes pollution such as acid rain, which hurts animals and plants around the world; c) potential source of global political unrest, given that many nations are reliant upon other nations for these non-renewable energy resources. the governments are aware of the non-renewable energy problems we are facing. research is being done on how to best use the earth’s energy resources while keeping it cost effective. of course, when the non-renewable energy sources are depleted we will have no choice but to find an alternate energy solution. solving the climate and environment change must be the action of governments in implementing strategies of growing the investments in renewable energy sector. also, this have to be one of the biggest problems of the people, because they must be awared of the near future climate disaster. so, they have to change their actual way of living by consuming only green energy for their needs. the literature in green energy that i studied is about to make people and governments understand the importance of using only renewable energy alternatives in order to satisfy their needs. an important step was made by the governments of the industrialized countries who were making big improvements in investing in the green sector. this fact is proved by the following reports made by the most important authorities regarding green energy sector, such as: clean energy trends , issued by the clean tech market authority in us, global trends in sustainability performance management, issued by the economist intelligence unit in us, renewable energy future for the developing world, issued by isses – international solar system society in us. revised literature in the field there are a lot of people in important key jobs regarding green energy sector and also scientists who believe that only a big investment in renewable energy is the way to solve the climate and environment change. bruce piasecki, the president of the ahc group (a management consulting firm since ), defines new directions in capitalism and reshape the purposes of corporate environmental and energy strategy in his books. jeremy rifkin, the founder and president of the foundation on economic trends and the author of seventeen bestselling books on the impact of scientific and technological changes on the economy, the workforce, society, and the environment, has been one of the most important advisors to the european union for the past decade, on issues related to climate change and energy security. the name of rajendra k. pachauri, director general of teri and chairman of the ipcc, has become synonymous with climate change and the environment, receiving the nobel peace prize on behalf of the ipcc. internationally recognized as a leading global thinker and leader of research, rajendra’s passion lies in disseminating greater knowledge about man-made climate change and helping lay the foundations for the measures that are needed to counter such change. the need to find alternative energy sources as soon as possible as of december , nuclear reactors exist in the world. the united states produces the most nuclear power, providing % of the total electricity it consumes. as of , france produces % of its electrical power from nuclear reactors, which is the highest percentage in the world. this form of energy is risky to produce and many people worry about the long term effects. the chernobyl disaster is probably the most famous nuclear power disaster in history. obviously, people do not want something like that to ever happen again. barring any other awful nuclear reaction accident, radioactive waste is still produced by this energy source. this remains in the environment for thousands of years. people are very worried about the effects of radiation on the body. once the uranium is depleted, nuclear energy is lost to us forever, and we find ourselves even deeper in the energy crisis then we were before. besides the depletion of the non-renewable energy sources, they add to the energy crisis due to their impacts on the environment even just to harvest them. oil fields are becoming scarcer and mining is becoming a profession of the past. the harvesting of these resources damages the earth and permanently depletes some of the natural resources it has to offer us. we must solve this energy crisis while it is still just a crisis and not a full blown disaster. climate change – one of top three concerns globally climate change is one of the top three concerns globally, on par with economic stability and terrorism, according to hsbc’s fourth climate confidence monitor. the online survey lightspeed research was conducted of , consumers in fifteen countries between august and september . on average percent of survey respondents strongly agree that climate change is among their biggest concerns. this ranges from percent in china to percent in the uk. eighteen percent of u.s. respondents say climate change is one of their biggest issues. the survey climate confidence monitor finds that percent of respondents in china claim to be making a significant effort to help reduce climate change, compared to percent in the uk, percent in the u.s. and percent in japan. the report also reveals that one in three people in vietnam, india and china believe climate change can be halted, compared to just one in twenty in france and the uk. survey respondents in hong kong and vietnam also rank climate change as their number one concern. in terms of creating jobs, more than half of respondents in brazil, india and malaysia strongly agreed their country would prosper and create new jobs by responding to climate change. in comparison, one-third of respondents in the uk and the u.s. think economic opportunities and new jobs can be created. the survey also indicates that businesses need to address climate change. nearly percent of respondents in france and percent in germany agreed that greater business investment is needed. ngos and individuals were seen as central to the effort, backed up by effective government intervention such as carbon taxes and emissions trading schemes, say researchers. another hsbc report indicates that annual capital investment in the green economy would grow from an annualized $ billion in to $ . trillion in . http://www.environmentalleader.com/ / / /hsbc-predicts-low-carbon-energy-market-to-triple renewable energy without slow growth – an overview greenpeace outlined a scenario in which percent of energy generation comes from renewable sources by while creating million jobs, for a price tag of around $ trillion in global investment, resulting in an percent decrease in co emissions. according to the greenpeace report, energy [r]evolution: a sustainable world energy outlook, such a drastic revolution in energy production is necessary, since even a percent decrease in co emissions by might not be enough to prevent runaway climate change scenarios. under the greenpeace scenario, co emissions will peak in before dropping by more than percent by . in its first edition of the energy [r]evolution report in , greenpeace had predicted that gw of renewable energy would be produced in . as of the end of , gw were being produced. the report makes several policy recommendations, such as phasing out all subsidies for fossil and nuclear fuel businesses, establishing legally binding targets for renewable energy, and strict efficiency standards. according to the report, conventional fuel sources receives an estimated $ - billion in worldwide subsidies, with coal alone receiving $ billion. the energy [r]evolution scenario outlines a scenario which creates about million jobs, with . million in the renewable sector alone, by . without adopting the policy recommendations of the report, however, only . million renewable jobs will be created. the renewable energy sector already employees two million people worldwide. the policy recommendations also state that the market for renewable technology will increase from $ billion today to more than $ billion by . http://www.greenpeace.org/international/global/international/publications/climate/ /fullreport.pdf http://www.greenpeace.org/international/global/international/publications/climate/ /fullreport.pdf actual energy consumption is expected to increase up to percent by , according to the report. implementing the policy recommendations in the report, including improved insulation and design for buildings, implementing efficiency standards and replacing heating systems with renewable technology, would decrease energy consumption by percent. greenpeace also reported that renewable energy resources alone have the potential to generate up to times current global power demands. the report estimates potential savings in fuel costs of switching to renewable systems at $ billion per year. however, the annual investment necessary between now and is estimated to be $ billion, though without further investment costs beyond that time horizon. under current policies, greenpeace estimates global energy investment of $ . trillion dollars from now until , while under the energy [r]evolution scenario, global investment reaches $ . trillion. renewable energy sector grows despite recession the recent economic slowdown appears to not have impacted the renewable energy sector as many had feared. renewable energy has actually been exhibiting strength in recent years according to a new study. the renewable energy policy network for the st century recently released their study, which was requested by the united nations. the study found that renewable energy installations outpaced fossil fuel installations in in europe and the united states. according to the study, percent of new energy installations in europe were in the form of renewable energy. in the united states, just over percent of new energy installations were from the renewable energy sector. overall, the study concluded that renewable energy instalments should account for a larger percentage of installations than fossil fuels across the world and not just in europe and the united states in . this is in large part due to china’s renewable energy sector growth. in , china installed gigwatts of renewable energy across the country. china also increased their status as a world leader in building renewable energy equipment, such as their percent hold in solar panels and percent hold in wind turbine manufacturing. in , the study found that percent of energy capacity across the globe was in the form of renewable energy. however, only percent of electricity needs were met through renewable energy in . those behind the study believe that will be a major year for the renewable energy sector and will set a precedence for years to come. across the globe, renewable energy policies and investments appeared to also be of importance in . countries now have renewable energy policies compared to only in . also, investment into the united nations’ environment program was $ billion despite the economic recession. however, this was a slight decrease from the $ billion invested in . however, some involved still express concern regarding the state of renewable energy across the globe, especially in terms of the impact on climate change. united nations’ environment program executive director achim steiner stated: “there still remains, however, a serious gap between the ambition and the science in terms of where the world needs to be in to avoid dangerous climate change.” eu nations confident on renewable energy goals most eu member states are confident that they will be able to ramp up the production of renewable energies to meet their production targets, according to national forecast documents submitted to the european commission. the eu’s renewable energy directive set national targets for renewables in order to reach a % share in the eu’s overall energy mix by . to ensure that the goals are reached, the directive set “indicative trajectories” – intermediate targets – for each member state. countries were obliged to draw up national renewable energy action plans by the end of june , setting out measures on how they intend to keep up with their trajectories. the directive also offers member states the option to use “statistical transfers” to sell excess renewable credits to another country to contribute towards their targets. but they can only do this if they meet their own intermediate targets. six months before handing in their national action plans, member states are due to submit to the european commission forecast reports, estimating their potential excess production or demand for renewable sources in addition to domestic sources. so far, twenty countries have submitted production forecasts on delivering the eu’s objective of sourcing % of its energy from renewable sources by . in the country reports, member states estimate whether they expect production to exceed their interim domestic targets or whether they will need help from others to meet them. many member states, including france and the czech republic, said they expect to follow indicative trajectories that set midterm goals up to . this means that they do not expect to need help to meet their own targets, nor to contribute towards others’ goals. a few member states announced that they expect to exceed their goals. these countries expressed an interest in transferring the volumes that exceed their indicative trajectories to other countries to help them achieve their goals. these include sweden and denmark, where renewables penetration is already above average. germany and spain also fall into that category. only a few nations expressed doubt as to whether they would reach their domestic production goals. belgium said it “does not exclude the possibility of using the cooperation mechanisms” to meet its objective, while the netherlands pledged to make “temporary efforts” to step up its energy policy “in the unlikely event” that it does not manage to keep up with its indicative trajectory. potential cooperation projects include a pan-mediterranean solar plan, an idea raised by france and spain, and offshore wind parks in germany. moreover, several other countries stressed the need for further development of interconnections. ireland called for the development of offshore grids to harness wind power, while spain and portugal expressed concern about the lack of electricity links between the iberian peninsula and the rest of europe. one of the most optimistic countries was spain, which estimated that it would cover . % of its energy consumption from renewable sources by , overshooting its % target. moreover, madrid would exceed its % target for renewables in electrical power generation by . %. to accomplish this feat, spain would need to more than double its share of renewables in its energy mix – which currently stands at . % – in the next decade. moreover, spain has a poor track-record in complying with eu renewables legislation. it came second only to italy regarding the number of infringement procedures started against member states by the european commission under the renewable electricity directive. however, the spanish government said achieving the target will be possible with greater energy savings. renewable energy investments in renewable energy investment may rise by percent in as government stimulus funds mainly in the u.s. and europe are spent wind turbines and solar panels. ’’spending may rise to between $ billion and $ billion in from $ billion in ”, said bloomberg new energy finance chief executive officer michael liebreich at the beginning of . governments in the u.s., china, europe and other regions have earmarked $ billion for clean energy projects, with two-thirds of that money expected to be spent through , new energy finance estimates. construction of windmills, solar power and biomass plants will continue even after united nations negotiators failed to reach a binding treaty to limit carbon dioxide emissions from fossil fuel plants. ’’we’re going to be negotiating on the climate for the next years’’, liebreich said. in , china replaced the u.s. as the biggest investor in renewable energy for the first time in at least five years as the asian nation raced to meet rising demand for power and reduce carbon emissions. china vs usa in renewable energy investments china invested $ . billion in wind turbines, solar panels and other low- carbon energy technologies in , said bloomberg new energy finance from london. the u.s. spent about half as much last year, or $ . billion, slipping to second. demand for electricity, fuels and heating has soared in china as millions of farm workers moved to the cities, found jobs and bought appliances. economic growth averaging percent a year the past three decades made the country of . billion people the largest polluter, forcing the government to implement tougher emissions rules and set clean-energy targets. “the rise of china as an investor in clean energy is a striking development that reflects in part beijing’s determination to be at the forefront of manufacturing key technologies such as wind turbines and solar pv modules,” said liebreich. “investment in the u.s. was held back last year by a shortage of long-term private sector finance for projects.” china has pledged to reduce its carbon-dioxide output per unit of gross domestic product by percent to percent of levels by . premier wen jiabao in january called pollution in his nation “grim” and said the government will curb emissions from power plants, cement and steel producers. u.s. investments in clean energy fell percent from a year earlier ( ), reflecting tighter credit conditions amid the worst recession since world war ii and the lack of a federal plan encouraging renewable power. worldwide, only percent of the $ billion of global economic stimulus packages earmarked for clean energy had been spent by the end of , new energy finance estimates. two-thirds of the spending is scheduled for and , which follows ’s $ billion. china, the world’s third-largest economy, boosted the installed capacity of renewable energy projects to . gigwatts, mainly in the form of wind turbines and biomass plants. that’s the equivalent of medium-sized coal plants. low- carbon energy now accounts for percent of the total. the u.s. still leads the world in installed renewable capacity at . gigawatts, or percent of the total. spending in is poised to climb, reversing ’s percent decline, with much of the $ billion of the clean-energy stimulus money being spent, new energy finance said. venture capital spending was the highest in the u.s., accounting for percent of the world total, new energy finance said in a fact book distributed at its annual conference in london this year. the u.k. was the third-largest renewable investor in , accounting for percent of the g- total, followed by spain, brazil, germany and canada. conclusion because non-renewable energy is energy that could become depleted, people have to be thrifty with it. if the nations persist with their present behaviour, oil will be depleted within years, gas will be depleted in years and we will have coal till the year . another minus of non-renewable energy is that it is more pollutant than renewable energy. polar ice is melting, ocean and seawater levels are rising, and air pollution is every day’s reality. because of these facts we are developing techniques to mass-produce renewable energy. no doubt our planet is full of energy resources but it is our duty to exploit only those reserves that cannot cause harm to the environment. the constant consumption of fossil fuels has evolved threats of fuel extinction but we are provided with many alternates. need of the hour is to invent not only cost effective but also environment friendly methods (to limit the hazardous residues) to fulfil the increasing demand of power. i wrote this article to aware the people about the near climate and environment change and make them understand that only an action of big proportion (governments and people) will make a green earth again. i believe that the actions already taken by the important industrialized countries in the sector of renewable energy investments is only a small part of the future ones. we all have to work together for our goal: a better and a safest way of living is good for everyone. we have to learn how to live in a healthier way again. references botkin, b. daniel, perez, diana, , powering the future: a scientist’s guide to energy independence, pearson education, inc., new jersey, p. - . daly, e. herman, , ecological economics. principles and applications, island press, washington, p. - . daly, e. herman, , beyond growth: the economics of sustainable development, beacon press, boston, p. - . database of u.s. state incentives for renewable energy (dsire). ebrd renewable development initiative. ecn energy policy studies. farley, joshua, erickson jon, daly, e. herman, ecological economics: a workbook for problem-based learning, island press, washington, , p. - . global trends in sustainability performance management, , economist intelligence unit, the economist, sponsored by sap. holm, dieter, anch, d., , renewable energy future for the developing world, white paper, ises, international solar energy society. iea global renewable energy policies and measures database. information on renewable energy in central and eastern europe. jackson, tim, , prosperity without growth: economics for a finite planet, earth scan publishing, london, p. - . mckay, david jc, , sustainable energy without the hot air, uit cambridge ltd, england, p. - . meadows, donella h., randers jorgen, meadows, dennis, , limits to growth – the -year global update, chelsea green publishing company, white river junction, vermont, p. - . pernick, ron, wilder, clint, gauntlett, dexter, winnie, trever, , clean energy trends , the clean tech market authority. victor, peter a., , managing without growth. slower by design, not disaster. advances in ecological economics, edward elgar publishing limited, cheltenham, uk, p. - . the resources crisis econstor make your publications visible. a service of zbw leibniz-informationszentrum wirtschaft leibniz information centre for economics stern, louis w.; zahzah, tayeb article — digitized version the resources crisis intereconomics suggested citation: stern, louis w.; zahzah, tayeb ( ) : the resources crisis, intereconomics, issn - , verlag weltarchiv, hamburg, vol. , iss. , pp. - , http://dx.doi.org/ . /bf this version is available at: http://hdl.handle.net/ / standard-nutzungsbedingungen: die dokumente auf econstor dürfen zu eigenen wissenschaftlichen zwecken und zum privatgebrauch gespeichert und kopiert werden. sie dürfen die dokumente nicht für öffentliche oder kommerzielle zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. sofern die verfasser die dokumente unter open-content-lizenzen (insbesondere cc-lizenzen) zur verfügung gestellt haben sollten, gelten abweichend von diesen nutzungsbedingungen die in der dort genannten lizenz gewährten nutzungsrechte. terms of use: documents in econstor may be saved and copied for your personal and scholarly purposes. you are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public. if the documents have been made available under an open content licence (especially creative commons licences), you may exercise further usage rights as specified in the indicated licence. www.econstor.eu r a w m a t e d a ~ the resources crisis by louis w. stern, tayeb zahzah, new york * this arucle utilizes a new concept of supply and demand for raw materials. it emphasizes the need for the use of long run economics rather than short run analysis in the determination of a fair price for raw commodities. t he october war and the oil embargo which followed could have brought us to a new era of military occupation of oil producing countries and possibly to world war ii . will we again ex- perience the same anguish when another raw material is in short supply? the future will pay tribute to the present world leaders for having kept a low tone during the recent energy crisis. conflicts, although serious, were low keyed by both the heads of oil produc- ing countries and those of consuming countries. the growth of japan, germany and the european world was brought to a halt because one raw material, petroleum, lacked. balances of trade shifted from red to black for some countries, from black to red for others and from red to even redder for some less developed countries. sug- gestions ranging from invading the middle east to using the jews as a scapegoat were made in private as well as in public. "artifical or real shortage?", was the topic of much speculation a few months ago. however, questions, suggestions and propositions led to one conclusive warning: the world resources of petroleum are depleting. the price of petroleum moved from approximately $ . /barrel in may to $ . /barrel in november , an aver- age increase of p.c. a year . why did the price of petroleum rise by p.c. in three years, thus allowing oil exporting countries to increase their income per barrel of oil by p.c. ? what has brought the arabs to the * baruch college, city university of new york. i petroleum press service, may , pp. , december , pp. . us congress senate committee on finance ( : ), hearing on profitability of domestic energy company operation. successful use of oil as a weapon? has the law of supply and demand failed to regulate? the answers to these questions go far beyond the present situation in the middle east. they lie in the concept of fair prices for raw materials, rather than the prices imposed only by the pres- ent artificial equilibrium of demand versus supply. the present price of raw materials does not take into consideration future supply and demand but deals instead with present supply and demand. let us examine the two extremes of the continuum of production and process of raw materials, one at the mine or well and the other at the retail outlet. causes of falling raw material prices "instead of following the trend of international prices for other commodities, the prices of oil started to fall in . they continued in their decline until the oil producing countries joined together and formed the organization of petro- leum exporting countries (o.p.e.c.). oil prices stopped declining after august , but they re- mained frozen at the level they reached at that time until the end of . after that, they rose a little to a level that was still lower than their level in ." the explanation of this adverse trend in the price of any raw commodity is found in the concept of supply and demand. in the short run analysis, supply means production which, because of the fantastic technological progress, increases at a higher rate than demand, and therefore generates sheik ahmed zaki y a m a n i , united nations a/pv , april , pp. . intereconomics, no. , raw materials a lower price. but in the long run analysis, supply, meaning totat available known and limited re- sources, is depleting at an increasing rate. at the other extreme of the continuum, the con- sumer side, only the short term effect is reflected. production increases; price decreases. the de- crease in price may not be passed on directly to the consumer but may be reflected in an improv- ed product at the same price. since the average per capita income increases at about $ . a year in industrial countries the consumption of products, steel for example, increases proportionally and is balanced by in- creases in production rather than by increases in price. here the law of supply and demand does not act as a regulator. in short term analysis, re- sources are not scarce. misled consumers it is true that for the present, resources are not scarce but the club of rome in "limits to growth" lists twenty vital minerals which, with the most conservative index of depletion and the most optimistic factor for reserves not yet dis- covered, will be entirely consumed by the year obviously the energy crisis should be called the resources crisis and may in the next decade or two repeat itself for every mineral resource. optimists may hope that by we will have found substitutes for most raw materials. such hope would certainly not be that of scholars who have understood the principle of conservation, i.e. "only nothing comes from nothing", and who have understood that natural resources are the only inputs to our whole life system. any substi- tute for one resource is nothing more than an in- crease in the rate of depletion of another, e.g. in- creases in the use of coal as a substitute for petroleum. the consumer, an economic animal, when he has the purchasing power which he has in the united mohamed a k k a o h e , capitaux etranger et liberation eco- nomique: i'exp~rience aig~rienne, maspero, pp. . s d. l. m e a d o w s etal., the limits to growth. a potomac associates book, , pp. . states, canada and sweden, will try to maximize his welfare. but as abraham maslow has demon- strated, the needs of man are not static and even the concept of the basic needs varies. the type and definition of basic needs change with the in- crease of per capita income. a television and a car, for instance, are necessities in the us (gnp per capita $ in ) , but they are luxuries in algeria ($ gnp per capita in ) long-term determination of prices president haouari boumedienne of algeria advo- cates austerity for the developed countries. speaking to the united nations he stated, "in particular, it is necessary to eliminate the phe- nomena of overconsumption and gadgetization and, more generally, the waste, which runs ram- pant throughout the developed economies" is this realistic? can gadgetization be eliminated? of course not. "gadgetization" is the logical con- sequence of abundance. "gadgetization" and overconsumption cannot be stopped by rules and laws but they can be slowed down by a new def- inition of supply when raw materials are involved. supply, demand, price and their interrelationships are the only tools that developed countries, in the non-socialist and non-communist world, can use to shape consumer's behavior and moderate his needs. but in order to be effective, price must be determined by the long run analysis. when the per capita income increases there is a corresponding increase in the demand for cer- tain products, gasoline for example. in the long- run economics, there are two ways to slow down this change in demand: one way would be to maintain a constant supply of the raw material. however, this is not advisable because of its negative byproduct, namely rationing and black marketing. another method is to increase both a. h. m a s l o w , motivation and personality. second edition, new york, , pp. . us bureau of census, statistical abstract of us . background notes by us department of state, august , pp. . discours du president haouari boumedienne, session extra- ordinaire de i'assembl~e g~n~rale des nations unies, aprit , p. . resource real price computation model no. of years base price incremental of available factor supply (hypothetical) z real price reflecting depletion factor known global reserve aluminium $ /ton . copper $ /ton . iron $ /ton . petroleum $ /bbl . $ . /ton $ . /ton $ . /ton $ . /bbl . x tons x tons x tons x bbls s o u r c e : data taken from meadows et al., the limits to growth, page . intereconomics, no. , raw materials the supply and the price. the increase in price should reflect both changes in demand and a change in the rate of depletion of the raw mate- rial, here petroleum. this increase in the price will serve as feedback to the consumer who will of course reduce his demand. conclusion and recommendations as stated earlier, the present prices of most raw materials do not consider an important factor: the rate of the world resources depletion. the price of raw materials must not be left to a short-sight- ed application of demand and production but must be tied to the "depletion factor". an example of the depletion factor can be seen by considering all known world resources of all minerals that may be depleted within the next one hundred years. we must determine a reason- able base price, either the actual price or a nego- tiated price. then determine the depletion factor which has an inverse relationship to the number of years of available resources. compute the real price which is the minimum price that must be paid for the raw material: p r - phz, where pr = real price, pt, = base price, z = depletion factor. the table on p. is an example of the compu- tation of the real price for four raw materials. of course, more elaborate and dynamic models could be developed by a panel of experts in sta- tistics, economics and management science. an international body such as the world bank with a team of experts representative of producers of raw materials from developed and developing countries is in our opinion the best choice for introducing what is called management of world resources. a realistic and early approach to the mineral re- source problem will avoid some sporadic and possibly fatal crises, will force conservation, stim- ulate efficient use of raw materials, stimulate re- search for new resources, contribute to cooper- ative rather than competitive international rela- tionships, prevent the otherwise inevitable forma- tion of opec-like cartels, and may even help to leave our children, if not a heavenly and peaceful world, at least not an empty one. after all, what is heaven to a hungry man? publications of the hamburg institute for international e c o n o m i c s new publication j~rgen langer subventionierung der deutschen werftindustrie (subsldlsauon of the german shipbuilding industry) the volume of assistance measures in shipbuilding has grown steadily for more than ten years. in the present study the distribution of subsi- dies and their results and expediency is being judged within the scope of an empirical analysis. the perceptions obtained by this analysis of results form the basis of suggestions for a more efficient subsidisation policy for shipbuilding in which a necessary higher integration of sec- toral and regional shipbuilding policy has been hammered out. (in german language.) large octavo, pages, , price paperbound dm .- isbn - - - v e r l a g w e l t a r c h i v g m b h - h a m b u r g intereconomics, no. , cqy volume cover and back matter john ryland university: library -:" studies in comparative communism an international interdisciplinary journal some recent and forthcoming articles of interest: leadership roles in modern china: the kuomintang and communist experiences by robert e. bedeski a comparative study of member payment systems used in collective farms in the soviet union and the people's republic of china by frederick w. crook and elizabeth f. crook power and personality in china: mao tse-tung, liu shao-ch'i and the politics of charismatic succession by lowell dittmer some psychological hypotheses on mao tse-tung's personality by herbert kupper chinese and soviet policies in southeast asia by charles b. mclane the sino-soviet conflict and the marxist-leninist theory of develop- ment by r. judson mitchell chinese politics and the public health issue by michel oksenberg a comparison of the current chinese and soviet central committees by derek j. waller and robert h. donaldson elite conflicts in chinese politics: a comparative note by yung wei textbooks on the soviet union, eastern europe, and china by steven goldstein, erik p. hoffmann, and barbara w. jancar the sino-soviet conflict and the " problem " parties rumania (robert r. king), albania (peter r. prifti), yugo- slavia (a. ross johnson), the pathet lao and the japanese cp (paul langer), north vietnam (victor funnell), north korea, cuba and others. the editors plan special issues devoted to urban and national minorities problems, political succession, civil-military relations, and personality and politics in communist systems. inquiries and manuscripts on these subjects, as well as on comparative analyses of divided countries and across political systems, are invited. graduate student essays: advanced graduate students in the social sciences, are encouraged to submit manuscripts of article and research- note length. published quarterly by the school of international relations, university of southern california, vkc , university park, los angeles, calif. subscriptions: individuals $ a year, institutions $ a year (postage included) use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core science and technology in the development of modern china an annotated bibliography bygenevievec. dean this bibliography indicates the current state of knowledge about chinese science and technology, with concentration on the period since . nearly , entries list books, articles, unpublished papers and dissertations that have appeared in the english, european and japanese languages up to the end of . arranged within five broad categories covering science and technology in relation to growth, policy and activity, the work provides a reference guide to important secondary source materials which range from analyses of visits to china to reviews and other bibliographical aids. one cloth volume isbn o £ . (us $ . ) i bloomsburyplace lon don wc a qa england orbis a quarterly journal of world affairs volume xvii winter number albert wohlstetter nuclear threats and allied responses in an era of negotiation colin s. gray rethinking nuclear strategy william e. griffith the fourth middle east war. the energy crisis and u.s. policy c. g. jacobscn strategic considerations affecting soviet policy toward china and japan robert mcgeehan and europe's foreign policies: economics, politics, steven j. warnecke or both' c gordon bare the north sea triangle rene albrecht-carrie trade policy and atlantic partnership yair evron israel and the atom: the uses and misuses of ambiguity francis russell formulating foreign policy robert g wesson viability of the leninist synthesis robert d. tomasek caribbean exile invasions: a special regional type of conflict u.s -south asian relations in the 's: a conference report review articles on important new books in the field of international relations orbis is published four times yearly, in february, may, august and november. individual copies: $ . . subscriptions: one year, $ . ; two years, $ . ; three years, $ . . address orders to: the foreign policy research institute market street, suite , philadelphia, pa. printed in great britain by the eastern press, ltd . london and reading use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core from a e i . . . the future of the china market: prospects for sino-american trade by edward neilan and charles r. smith the authors, both news reporters who specialize in asian affairs, contend that china provides american businessmen with important opportunities for trade and finance. the study, published jointly by aei and the hoover institution, includes the findings of the authors' poll of leading american government, banking and academic specialists on china trade. they dis- cuss political, social and defense considerations, as well as the short- and long-term prospects for sino-american trade. pages paperback, $ . malaysia, a case study in successful development by wolfgang kasper wolfgang kasper analyzes malaysia as one of the frequently overlooked, relatively successful cases of development. what are the factors behind the relative development success of malaysia? what lessons can be drawn for development policy in other less developed countries? these two ques- tions are the focus for this exhaustive and provocative study. pages paperback, $ . american enterprise institute for public policy research please send me copies of the future of the china market @ $ . per copy copies of malaysia @ $ . per copy quantity discount information available payment must accompany orders of under $ . name. address_ city state zip_ make checks payable to: american enterprise institute, seventeenth street, n.w. washington, d.c. use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core october , volume , number american association for the advancement of science science serves its readers as a forum for the presentation and discussion of important issues related to the advancement of science, including the presentation of minority or conflicting points of view, rather than by publishing only material on which a consensus has been reached. accord- ingly, all articles published in science-including editorials, news and comment, and book reviews -are signed and' reflect the individual views of the authors and not official points of view adopted by the aaas or the instituitions with which the authors ar-e affiliated. editorial board h. s. gutowsky arthur d. hasler rudolf kompfner daniel e. koshland, jr. alfred brown james f. crow seymour s. ke y frank press gardner lindzey raymond h. thompson edward . wilson frank w. putnam maxine singer gordon wolman editorial staff editor philiiw h. abelson publisher business manager william bevan hans nussbaum managing editor: robert v. ormes assistant editors: ellen e. murphy, john e. ringli assistant to the editor: nancy teimourian news andl comment: john walsh, luther j. carier, deborah shapley, robert gillette, nicho- las wade, constance holden, barbara j. culliton, scherraine mack research news: allen l. hammond, william d. metz, thomas h. maugh il, jean l. marx, ar ihur l. robinson book revie,vs: sylvia eberhart, katherine liv- ingso' n, ann seliz-petrash cover editor: grayce fingeit editorial assistants: margare'i' allen, isabella boijldin, blair burns, eleanore buiz, mary dorf- man, judi'rh givelber, corrine harris, nancx' harinagel, oliver heatwole, christine karlik. gina bari kolata, margaret lloyd, jean rock- wood, patricia rowe, leah ryan, john schauer, lois schmitt, michael schwar'rz, richard semi- klose, ya li swigart gui(de to scientific instruments: richard sommer membership recruitmient: g wendolyn huddle; sutbscriptioni recordls and memnber records: ann raglan d advertising staff director production manage, earl j. scherago patty wells admertising sales maniager: richard l. charles sales: new york. n.y. : herbert l. burklund, w. st. ( -pe- - ); scotch plains, n.j. : c. richard callis, unami lane ( - - ); chicago, ill. : john p. cahill, room , n. michigan ave. ( -de- - ); bev- erly hills, calif. : winn nance, n. la cienega blvd. ( - - ) editoriial correspondence: massa- chusetts ave., nw, washington, d.c. . phones: (area code ) central office: - ; book re- views: - ; business office: - ; circula- tion: - ; guide to scientific instruments: - ; news and comment: - ; reprints and permissions: - ; research news: - ; reviewing: - . cable: advancesci, washington. copies of "instructions for contributors" can be obtained fromn the editorial office. see also page xv, science, september . advertising cor- respondence: room , w. st., new york. n.y. . phone: -pe- - . sci:ence the urgent need for energy conservation during the last months, the mass media have devoted considerable attention to the "energy crisis." but obvious trauma has not materialized, and from surface evidence one might conclude that we had been treated to another instance of crying wolf. the sad fact is that we are headed for substantial difficulties, even if the arab countries refrain from boy- cotting us. we avoided gasoline shortages this summer, but at the cost of insufficient production of heating oil for the coming season. by such patchwork measures we may stave off the moment of truth for a short time, but the trends seem inexorable. consumption of petroleum and its products continues to rise and currently is percent above consump- tion last year. domestic production of oil is decreasing slowly, while total imports are running more than percent above what they were a year -ago. three years ago, imports cost $ billion. this year they will amount to about $ billion, but the sum does not fully reflect present realities. this spring, libya received $ . per barrel for its oil. it now gets $ . . other countries have not yet advanced their prices so sharply, but they will increase them. if rising trends in importation and costs continue, the bill next year could exceed $ billion. this year we have been able to pay for imported oil, aided sub- stantially by agricultural exports, but there were unpleasant side effects at the supermarkets. good crops elsewhere next year could cause world food prices to drop and leave the united states with an unsustainable deficit in balance of payments. already libya has talked of refusing to accept dollars in payment for oil. in itself this is not important, for we obtain only a small fraction of our supplies there. however, examples set by libya have recently been proving highly contagious. we would help ourselves and many others if we lessened our de- pendence on foreign petroleum. we could do this in three ways-by increasing domestic production of oil, by substituting coal for oil, and by conservation. by far the most effective action we could take now is conservation. the other steps could be implemented only slowly, and they would create environmental problems. a determined effort at con- servation could have an instantaneous effect. an obvious target is the automobile, which is the largest consumer of liquid hydrocarbons. recently, it has been pointed out that half the consumption of gasoline in autos occurs on trips of miles and less. this winter some citizens are likely to suffer acutely from lack of fuel oil. but if everyone would set his thermostat °c lower, percent less heating oil would be burned, and there would be enough for all. the nixon administration is currently engaged in planning a -year research and development program for energy, with costs targeted at $ billion annually. up to the present, the government has devoted most of its energy funds to items like the breeder reactor, which might make a small energy contribution or years hence. moreover, there is a long road from nuclear energy to large amounts of hydrocarbons. our civilization is based on hydrocarbons, from which we derive percent of energy consumed. of this, most is burned in the form of liquid hydrocarbons. this convenient form of energy is essential to agriculture and transportation and will continue to be for at least years. during that interval, we will not be able to function or even exist without petroleum. it is to be hoped that, in formulating the new program, government planners will give adequate attention to the main chance-hydrocarbons -and to the quick fix-conservation.-philip h. abelson o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ the urgent need for energy conservation philip h. abelson doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the trademark of aaas. is a registeredscienceadvancement of science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for thescience by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ foreword editorial foreword minhua shao • francesco ciucci , • jiazhao wang received: may / accepted: may / published online: may � springer science+business media dordrecht electrochemical energy technologies have been considered as clean and sustainable approaches to mitigating the more and more serious global energy crisis. the widespread adoption of electrochemical energy conversion and storage devices, such as fuel cells, advanced batteries, photovoltaic cells, supercapacitors, and electrolyzers, etc., has been hindered by their high cost, low efficiency, short lifetime, and insufficient energy/power densities. in order to exchange and discuss recent research results, enhance collaboration between research groups/industries, and promote the commercialization of newly developed tech- nologies, we organized an ise satellite meeting on new devices for energy conversion and storage at the hong kong university of science and technology (hkust) during october – , . this conference was co-chaired by profs. guohua chen (hkust), christos comninellis (ecole polytechnique fédérale de lausanne, switzerland) and gerardine botte (ohio university, usa). over participants from different countries attended this conference. three plenary lectures were delivered by profs. nenad markovic (ar- gonne national laboratory, usa), jean-marie tarascon (college de france, france) and hubert girault (ecole polytechnique fédérale de lausanne, switzerland). in addition, keynote lectures, invited talks, oral presentations, and poster presentations were given during the conference. all the presentations were related to one of the following electrochemical energy conversion and storage devices: fuel cells, lithium (sodium)-ion bat- teries, photovoltaic cells, electrolyzers, flow batteries, supercapacitors and metal-air batteries. high quality papers presented in the conference were selected and published in this special issue of journal of applied electrochemistry after undergoing a rigorous peer-review process. we would like to take this opportunity to express our deep appreciation to the organizing committee including profs. guohua chen, christos comninellis, gerardine botte, minhua shao (hkust), kwong yu chan (hku), francesco ciucci (hkust), haitao huang (hk polyu), jang kyo kim (hkust), quan li (cuhk), fude liu (hku), yi-chun lu (cuhk), shihe yang (hkust), denis yu (hk cityu), and limin zhou (hk polyu). we also want to thank prof. gerardine botte and her editorial team for helping organize this special issue. & minhua shao kemshao@ust.hk department of chemical and biomolecular engineering, hong kong university of science and technology, clear water bay, kowloon, hong kong, people’s republic of china department of mechanical and aerospace engineering, hong kong university of science and technology, clear water bay, kowloon, hong kong, people’s republic of china institute for superconducting and electronic materials, university of wollongong, wollongong, nsw , australia j appl electrochem ( ) : doi . /s - - - http://crossmark.crossref.org/dialog/?doi= . /s - - - &amp;domain=pdf http://crossmark.crossref.org/dialog/?doi= . /s - - - &amp;domain=pdf 	foreword distributed model predictive control applied to a vav based hvac system based on sensitivity analysis ifac papersonline - ( ) – sciencedirectsciencedirect available online at www.sciencedirect.com - © , ifac (international federation of automatic control) hosting by elsevier ltd. all rights reserved. peer review under responsibility of international federation of automatic control. . /j.ifacol. . . © , ifac (international federation of automatic control) hosting by elsevier ltd. all rights reserved. . /j.ifacol. . . - distributed model predictive control applied to a vav based hvac system based on sensitivity analysis tejaswinee darure ∗ vicenç puig ∗∗ joseph yamé ∗ frédéric hamelin ∗ ye wang ∗∗ ∗ université de lorraine, centre de recherche en automatique de nancy, cnrs, umr , vandoeuvre les nancy , france ∗∗ institut de robtica i informtica industrial (csic-upc), llorens i artigas - , scientic park of barcelona, barcelona, spain abstract: this paper proposes a distributed model predictive control strategy for a hvac system that relies on its decomposition into subsystems based on the sensitivity analysis. an economic model predictive controller is implemented for every subsystem to optimize the operational cost of the building without compromising the thermal comfort of the occupants. also, this work demonstrates the coordination strategy between the subsystem controllers using the sensitivity analysis approach. a discussion about the coordination strategy with the convergence property is provided. finally, the proposed approach is illustrated using the benchmark building that considers the weather of nancy, france. keywords: vav type hvac system, distributed mode predictive control, energy optimization . introduction since last three decades, the energy crisis has been cer- tainly one of the strong motivation in the changes of the hvac industry towards more energy-efficient buildings without compromising the comfort. as energy require- ment and fuel consumption of heating, ventilation and air-conditioning (hvac) systems have a direct impact on the operational cost of a building as well as an impact on the environment. for this reason, building energy man- agement has become an important issue in many countries (eu, ). more sophisticated technological schemes are now being developed and implemented in the buildings to reduce energy consumption, as e.g., thermal storage, building energy management systems (bems), advanced direct digital control, variable-air-volume (vav) systems, variable frequency drives, etc. in order to improve the performance in hvac various control techniques are de- veloped e.g. gain scheduling in pid controllers, optimal control, adaptive control, nonlinear control, neural and fuzzy control methods. in above all, model predictive con- trol (mpc) is favored control method due to its obvious advantages of handling constraints and disturbances. the detailed analysis of the available hvac control techniques are summarized in afram and janabi-sharifi ( ). in large non-residential and commercial buildings, the hvac system must meet the varying needs of different spaces since different zones of a building may have dif- ferent heating and cooling needs. due to these reasons, � this work is supported by energy in time project funded by the european union within the th framework program fp -nmp, sub- program eeb.nmp. - : integrated control systems and method- ologies to monitor and improve building energy performance. distributed control strategies are becoming very popular (lamoudi, ). these control strategies hold various advantages as multivariable interactions, scalability and isolation in case of occurrence of faults. the class of dmpc methods are based on the type of decomposition of a large scale system into subsystems and the type of coordination between subsystem controllers. in the survey by afram and janabi-sharifi ( ) about dmpc methods applied to hvac systems, various approaches are found in the literature in the context of the type of the decomposition of centralized mpc problem e.g. primal an dual decom- position as in p. pflaum and m. alamir ( ), dantzing wolfe and bender’s decomposition as in petru-daniel mo- rosan ( ). in spite of the developments in the dmpc methods, much work is still needed to be done regarding its application to the hvac systems. in this work, we propose: i) a method to decompose the hvac building system into subsystems based on the sen- sitivity analysis and ii) the coordination strategy between the subsystem controllers considering the sensitivities of the neighboring subsystem controllers and the coupling information. for the illustration of the proposed method, we consider a benchmark hvac building system with vav systems. we consider every zone is provided with a vav box in which a damper manipulates the airflow of supply air with the constant temperature into the zones to maintain the ther- mal comfort. this supply air with constant temperature is provided by an air handling unit (ahu). the complexity of the centralized control increases exponentially as the number of zones increases. hence, we propose the dmpc approach to achieve the same performance as centralized th ifac conference on nonlinear model predictive control madison, wi, usa, august - , copyright © ifac distributed model predictive control applied to a vav based hvac system based on sensitivity analysis tejaswinee darure ∗ vicenç puig ∗∗ joseph yamé ∗ frédéric hamelin ∗ ye wang ∗∗ ∗ université de lorraine, centre de recherche en automatique de nancy, cnrs, umr , vandoeuvre les nancy , france ∗∗ institut de robtica i informtica industrial (csic-upc), llorens i artigas - , scientic park of barcelona, barcelona, spain abstract: this paper proposes a distributed model predictive control strategy for a hvac system that relies on its decomposition into subsystems based on the sensitivity analysis. an economic model predictive controller is implemented for every subsystem to optimize the operational cost of the building without compromising the thermal comfort of the occupants. also, this work demonstrates the coordination strategy between the subsystem controllers using the sensitivity analysis approach. a discussion about the coordination strategy with the convergence property is provided. finally, the proposed approach is illustrated using the benchmark building that considers the weather of nancy, france. keywords: vav type hvac system, distributed mode predictive control, energy optimization . introduction since last three decades, the energy crisis has been cer- tainly one of the strong motivation in the changes of the hvac industry towards more energy-efficient buildings without compromising the comfort. as energy require- ment and fuel consumption of heating, ventilation and air-conditioning (hvac) systems have a direct impact on the operational cost of a building as well as an impact on the environment. for this reason, building energy man- agement has become an important issue in many countries (eu, ). more sophisticated technological schemes are now being developed and implemented in the buildings to reduce energy consumption, as e.g., thermal storage, building energy management systems (bems), advanced direct digital control, variable-air-volume (vav) systems, variable frequency drives, etc. in order to improve the performance in hvac various control techniques are de- veloped e.g. gain scheduling in pid controllers, optimal control, adaptive control, nonlinear control, neural and fuzzy control methods. in above all, model predictive con- trol (mpc) is favored control method due to its obvious advantages of handling constraints and disturbances. the detailed analysis of the available hvac control techniques are summarized in afram and janabi-sharifi ( ). in large non-residential and commercial buildings, the hvac system must meet the varying needs of different spaces since different zones of a building may have dif- ferent heating and cooling needs. due to these reasons, � this work is supported by energy in time project funded by the european union within the th framework program fp -nmp, sub- program eeb.nmp. - : integrated control systems and method- ologies to monitor and improve building energy performance. distributed control strategies are becoming very popular (lamoudi, ). these control strategies hold various advantages as multivariable interactions, scalability and isolation in case of occurrence of faults. the class of dmpc methods are based on the type of decomposition of a large scale system into subsystems and the type of coordination between subsystem controllers. in the survey by afram and janabi-sharifi ( ) about dmpc methods applied to hvac systems, various approaches are found in the literature in the context of the type of the decomposition of centralized mpc problem e.g. primal an dual decom- position as in p. pflaum and m. alamir ( ), dantzing wolfe and bender’s decomposition as in petru-daniel mo- rosan ( ). in spite of the developments in the dmpc methods, much work is still needed to be done regarding its application to the hvac systems. in this work, we propose: i) a method to decompose the hvac building system into subsystems based on the sen- sitivity analysis and ii) the coordination strategy between the subsystem controllers considering the sensitivities of the neighboring subsystem controllers and the coupling information. for the illustration of the proposed method, we consider a benchmark hvac building system with vav systems. we consider every zone is provided with a vav box in which a damper manipulates the airflow of supply air with the constant temperature into the zones to maintain the ther- mal comfort. this supply air with constant temperature is provided by an air handling unit (ahu). the complexity of the centralized control increases exponentially as the number of zones increases. hence, we propose the dmpc approach to achieve the same performance as centralized th ifac conference on nonlinear model predictive control madison, wi, usa, august - , copyright © ifac distributed model predictive control applied to a vav based hvac system based on sensitivity analysis tejaswinee darure ∗ vicenç puig ∗∗ joseph yamé ∗ frédéric hamelin ∗ ye wang ∗∗ ∗ université de lorraine, centre de recherche en automatique de nancy, cnrs, umr , vandoeuvre les nancy , france ∗∗ institut de robtica i informtica industrial (csic-upc), llorens i artigas - , scientic park of barcelona, barcelona, spain abstract: this paper proposes a distributed model predictive control strategy for a hvac system that relies on its decomposition into subsystems based on the sensitivity analysis. an economic model predictive controller is implemented for every subsystem to optimize the operational cost of the building without compromising the thermal comfort of the occupants. also, this work demonstrates the coordination strategy between the subsystem controllers using the sensitivity analysis approach. a discussion about the coordination strategy with the convergence property is provided. finally, the proposed approach is illustrated using the benchmark building that considers the weather of nancy, france. keywords: vav type hvac system, distributed mode predictive control, energy optimization . introduction since last three decades, the energy crisis has been cer- tainly one of the strong motivation in the changes of the hvac industry towards more energy-efficient buildings without compromising the comfort. as energy require- ment and fuel consumption of heating, ventilation and air-conditioning (hvac) systems have a direct impact on the operational cost of a building as well as an impact on the environment. for this reason, building energy man- agement has become an important issue in many countries (eu, ). more sophisticated technological schemes are now being developed and implemented in the buildings to reduce energy consumption, as e.g., thermal storage, building energy management systems (bems), advanced direct digital control, variable-air-volume (vav) systems, variable frequency drives, etc. in order to improve the performance in hvac various control techniques are de- veloped e.g. gain scheduling in pid controllers, optimal control, adaptive control, nonlinear control, neural and fuzzy control methods. in above all, model predictive con- trol (mpc) is favored control method due to its obvious advantages of handling constraints and disturbances. the detailed analysis of the available hvac control techniques are summarized in afram and janabi-sharifi ( ). in large non-residential and commercial buildings, the hvac system must meet the varying needs of different spaces since different zones of a building may have dif- ferent heating and cooling needs. due to these reasons, � this work is supported by energy in time project funded by the european union within the th framework program fp -nmp, sub- program eeb.nmp. - : integrated control systems and method- ologies to monitor and improve building energy performance. distributed control strategies are becoming very popular (lamoudi, ). these control strategies hold various advantages as multivariable interactions, scalability and isolation in case of occurrence of faults. the class of dmpc methods are based on the type of decomposition of a large scale system into subsystems and the type of coordination between subsystem controllers. in the survey by afram and janabi-sharifi ( ) about dmpc methods applied to hvac systems, various approaches are found in the literature in the context of the type of the decomposition of centralized mpc problem e.g. primal an dual decom- position as in p. pflaum and m. alamir ( ), dantzing wolfe and bender’s decomposition as in petru-daniel mo- rosan ( ). in spite of the developments in the dmpc methods, much work is still needed to be done regarding its application to the hvac systems. in this work, we propose: i) a method to decompose the hvac building system into subsystems based on the sen- sitivity analysis and ii) the coordination strategy between the subsystem controllers considering the sensitivities of the neighboring subsystem controllers and the coupling information. for the illustration of the proposed method, we consider a benchmark hvac building system with vav systems. we consider every zone is provided with a vav box in which a damper manipulates the airflow of supply air with the constant temperature into the zones to maintain the ther- mal comfort. this supply air with constant temperature is provided by an air handling unit (ahu). the complexity of the centralized control increases exponentially as the number of zones increases. hence, we propose the dmpc approach to achieve the same performance as centralized th ifac conference on nonlinear model predictive control madison, wi, usa, august - , copyright © ifac distributed model predictive control applied to a vav based hvac system based on sensitivity analysis tejaswinee darure ∗ vicenç puig ∗∗ joseph yamé ∗ frédéric hamelin ∗ ye wang ∗∗ ∗ université de lorraine, centre de recherche en automatique de nancy, cnrs, umr , vandoeuvre les nancy , france ∗∗ institut de robtica i informtica industrial (csic-upc), llorens i artigas - , scientic park of barcelona, barcelona, spain abstract: this paper proposes a distributed model predictive control strategy for a hvac system that relies on its decomposition into subsystems based on the sensitivity analysis. an economic model predictive controller is implemented for every subsystem to optimize the operational cost of the building without compromising the thermal comfort of the occupants. also, this work demonstrates the coordination strategy between the subsystem controllers using the sensitivity analysis approach. a discussion about the coordination strategy with the convergence property is provided. finally, the proposed approach is illustrated using the benchmark building that considers the weather of nancy, france. keywords: vav type hvac system, distributed mode predictive control, energy optimization . introduction since last three decades, the energy crisis has been cer- tainly one of the strong motivation in the changes of the hvac industry towards more energy-efficient buildings without compromising the comfort. as energy require- ment and fuel consumption of heating, ventilation and air-conditioning (hvac) systems have a direct impact on the operational cost of a building as well as an impact on the environment. for this reason, building energy man- agement has become an important issue in many countries (eu, ). more sophisticated technological schemes are now being developed and implemented in the buildings to reduce energy consumption, as e.g., thermal storage, building energy management systems (bems), advanced direct digital control, variable-air-volume (vav) systems, variable frequency drives, etc. in order to improve the performance in hvac various control techniques are de- veloped e.g. gain scheduling in pid controllers, optimal control, adaptive control, nonlinear control, neural and fuzzy control methods. in above all, model predictive con- trol (mpc) is favored control method due to its obvious advantages of handling constraints and disturbances. the detailed analysis of the available hvac control techniques are summarized in afram and janabi-sharifi ( ). in large non-residential and commercial buildings, the hvac system must meet the varying needs of different spaces since different zones of a building may have dif- ferent heating and cooling needs. due to these reasons, � this work is supported by energy in time project funded by the european union within the th framework program fp -nmp, sub- program eeb.nmp. - : integrated control systems and method- ologies to monitor and improve building energy performance. distributed control strategies are becoming very popular (lamoudi, ). these control strategies hold various advantages as multivariable interactions, scalability and isolation in case of occurrence of faults. the class of dmpc methods are based on the type of decomposition of a large scale system into subsystems and the type of coordination between subsystem controllers. in the survey by afram and janabi-sharifi ( ) about dmpc methods applied to hvac systems, various approaches are found in the literature in the context of the type of the decomposition of centralized mpc problem e.g. primal an dual decom- position as in p. pflaum and m. alamir ( ), dantzing wolfe and bender’s decomposition as in petru-daniel mo- rosan ( ). in spite of the developments in the dmpc methods, much work is still needed to be done regarding its application to the hvac systems. in this work, we propose: i) a method to decompose the hvac building system into subsystems based on the sen- sitivity analysis and ii) the coordination strategy between the subsystem controllers considering the sensitivities of the neighboring subsystem controllers and the coupling information. for the illustration of the proposed method, we consider a benchmark hvac building system with vav systems. we consider every zone is provided with a vav box in which a damper manipulates the airflow of supply air with the constant temperature into the zones to maintain the ther- mal comfort. this supply air with constant temperature is provided by an air handling unit (ahu). the complexity of the centralized control increases exponentially as the number of zones increases. hence, we propose the dmpc approach to achieve the same performance as centralized th ifac conference on nonlinear model predictive control madison, wi, usa, august - , copyright © ifac distributed model predictive control applied to a vav based hvac system based on sensitivity analysis tejaswinee darure ∗ vicenç puig ∗∗ joseph yamé ∗ frédéric hamelin ∗ ye wang ∗∗ ∗ université de lorraine, centre de recherche en automatique de nancy, cnrs, umr , vandoeuvre les nancy , france ∗∗ institut de robtica i informtica industrial (csic-upc), llorens i artigas - , scientic park of barcelona, barcelona, spain abstract: this paper proposes a distributed model predictive control strategy for a hvac system that relies on its decomposition into subsystems based on the sensitivity analysis. an economic model predictive controller is implemented for every subsystem to optimize the operational cost of the building without compromising the thermal comfort of the occupants. also, this work demonstrates the coordination strategy between the subsystem controllers using the sensitivity analysis approach. a discussion about the coordination strategy with the convergence property is provided. finally, the proposed approach is illustrated using the benchmark building that considers the weather of nancy, france. keywords: vav type hvac system, distributed mode predictive control, energy optimization . introduction since last three decades, the energy crisis has been cer- tainly one of the strong motivation in the changes of the hvac industry towards more energy-efficient buildings without compromising the comfort. as energy require- ment and fuel consumption of heating, ventilation and air-conditioning (hvac) systems have a direct impact on the operational cost of a building as well as an impact on the environment. for this reason, building energy man- agement has become an important issue in many countries (eu, ). more sophisticated technological schemes are now being developed and implemented in the buildings to reduce energy consumption, as e.g., thermal storage, building energy management systems (bems), advanced direct digital control, variable-air-volume (vav) systems, variable frequency drives, etc. in order to improve the performance in hvac various control techniques are de- veloped e.g. gain scheduling in pid controllers, optimal control, adaptive control, nonlinear control, neural and fuzzy control methods. in above all, model predictive con- trol (mpc) is favored control method due to its obvious advantages of handling constraints and disturbances. the detailed analysis of the available hvac control techniques are summarized in afram and janabi-sharifi ( ). in large non-residential and commercial buildings, the hvac system must meet the varying needs of different spaces since different zones of a building may have dif- ferent heating and cooling needs. due to these reasons, � this work is supported by energy in time project funded by the european union within the th framework program fp -nmp, sub- program eeb.nmp. - : integrated control systems and method- ologies to monitor and improve building energy performance. distributed control strategies are becoming very popular (lamoudi, ). these control strategies hold various advantages as multivariable interactions, scalability and isolation in case of occurrence of faults. the class of dmpc methods are based on the type of decomposition of a large scale system into subsystems and the type of coordination between subsystem controllers. in the survey by afram and janabi-sharifi ( ) about dmpc methods applied to hvac systems, various approaches are found in the literature in the context of the type of the decomposition of centralized mpc problem e.g. primal an dual decom- position as in p. pflaum and m. alamir ( ), dantzing wolfe and bender’s decomposition as in petru-daniel mo- rosan ( ). in spite of the developments in the dmpc methods, much work is still needed to be done regarding its application to the hvac systems. in this work, we propose: i) a method to decompose the hvac building system into subsystems based on the sen- sitivity analysis and ii) the coordination strategy between the subsystem controllers considering the sensitivities of the neighboring subsystem controllers and the coupling information. for the illustration of the proposed method, we consider a benchmark hvac building system with vav systems. we consider every zone is provided with a vav box in which a damper manipulates the airflow of supply air with the constant temperature into the zones to maintain the ther- mal comfort. this supply air with constant temperature is provided by an air handling unit (ahu). the complexity of the centralized control increases exponentially as the number of zones increases. hence, we propose the dmpc approach to achieve the same performance as centralized th ifac conference on nonlinear model predictive control madison, wi, usa, august - , copyright © ifac distributed model predictive control applied to a vav based hvac system based on sensitivity analysis tejaswinee darure ∗ vicenç puig ∗∗ joseph yamé ∗ frédéric hamelin ∗ ye wang ∗∗ ∗ université de lorraine, centre de recherche en automatique de nancy, cnrs, umr , vandoeuvre les nancy , france ∗∗ institut de robtica i informtica industrial (csic-upc), llorens i artigas - , scientic park of barcelona, barcelona, spain abstract: this paper proposes a distributed model predictive control strategy for a hvac system that relies on its decomposition into subsystems based on the sensitivity analysis. an economic model predictive controller is implemented for every subsystem to optimize the operational cost of the building without compromising the thermal comfort of the occupants. also, this work demonstrates the coordination strategy between the subsystem controllers using the sensitivity analysis approach. a discussion about the coordination strategy with the convergence property is provided. finally, the proposed approach is illustrated using the benchmark building that considers the weather of nancy, france. keywords: vav type hvac system, distributed mode predictive control, energy optimization . introduction since last three decades, the energy crisis has been cer- tainly one of the strong motivation in the changes of the hvac industry towards more energy-efficient buildings without compromising the comfort. as energy require- ment and fuel consumption of heating, ventilation and air-conditioning (hvac) systems have a direct impact on the operational cost of a building as well as an impact on the environment. for this reason, building energy man- agement has become an important issue in many countries (eu, ). more sophisticated technological schemes are now being developed and implemented in the buildings to reduce energy consumption, as e.g., thermal storage, building energy management systems (bems), advanced direct digital control, variable-air-volume (vav) systems, variable frequency drives, etc. in order to improve the performance in hvac various control techniques are de- veloped e.g. gain scheduling in pid controllers, optimal control, adaptive control, nonlinear control, neural and fuzzy control methods. in above all, model predictive con- trol (mpc) is favored control method due to its obvious advantages of handling constraints and disturbances. the detailed analysis of the available hvac control techniques are summarized in afram and janabi-sharifi ( ). in large non-residential and commercial buildings, the hvac system must meet the varying needs of different spaces since different zones of a building may have dif- ferent heating and cooling needs. due to these reasons, � this work is supported by energy in time project funded by the european union within the th framework program fp -nmp, sub- program eeb.nmp. - : integrated control systems and method- ologies to monitor and improve building energy performance. distributed control strategies are becoming very popular (lamoudi, ). these control strategies hold various advantages as multivariable interactions, scalability and isolation in case of occurrence of faults. the class of dmpc methods are based on the type of decomposition of a large scale system into subsystems and the type of coordination between subsystem controllers. in the survey by afram and janabi-sharifi ( ) about dmpc methods applied to hvac systems, various approaches are found in the literature in the context of the type of the decomposition of centralized mpc problem e.g. primal an dual decom- position as in p. pflaum and m. alamir ( ), dantzing wolfe and bender’s decomposition as in petru-daniel mo- rosan ( ). in spite of the developments in the dmpc methods, much work is still needed to be done regarding its application to the hvac systems. in this work, we propose: i) a method to decompose the hvac building system into subsystems based on the sen- sitivity analysis and ii) the coordination strategy between the subsystem controllers considering the sensitivities of the neighboring subsystem controllers and the coupling information. for the illustration of the proposed method, we consider a benchmark hvac building system with vav systems. we consider every zone is provided with a vav box in which a damper manipulates the airflow of supply air with the constant temperature into the zones to maintain the ther- mal comfort. this supply air with constant temperature is provided by an air handling unit (ahu). the complexity of the centralized control increases exponentially as the number of zones increases. hence, we propose the dmpc approach to achieve the same performance as centralized th ifac conference on nonlinear model predictive control madison, wi, usa, august - , copyright © ifac tejaswinee darure et al. / ifac papersonline - ( ) – control architecture without compromising the thermal comfort of the occupants. the organization of this paper is as follows. section describes the details of the hvac building system un- der consideration for the demonstration of the proposed dmpc approach. section provides a brief discussion of the decomposition method to partition a system into the subsystems based on the sensitivity analysis. in section , the detailed control objectives are formulated. the proposed sensitivity based dmpc approach is explained in section to achieve the above control objectives. the proposed dmpc method is evaluated using the simulation platform for the benchmark hvac building system in sec- tion including a comparative analysis. finally, section concludes the paper and provides some paths for the future work. . hvac system of the building description in this section, we describe a benchmark school building which is used to demonstrate the proposed sensitivity based dmpc approach. the building has two floors with zones having a total area m . the cross sectional layout for the benchmark building is shown in figure . this fig. . building distribution: two floors with classsrooms each benchmark building is served by the vav based hvac system. each zone has a vav terminal, temperature sensor and a return air plenum. the vav terminal provides supply air flow to each zone in order to maintain the thermal comfort which is recirculated to the ahu. ahu contains heating coil, mixer, and supply fan. supply fan forces the supply air of constant temperature into the zones. the supply airflow rate at each zone is controlled such that the zone temperature is maintained in the thermal zones. then, the supply air is recirculated to the ahu. in ahu, the fraction of recirculated air is combined with fresh air in the mixer. then, the temperature of the air is increased in the heating coil which is an air-water heat exchanger. we consider that the hot water supply for the ahu unit is from production units as the heat pump or the boiler. . thermal zone model for each zone i, (i = , ..., n) where n = denotes the temperature of the zone by ti, ṁi mass flow rate at the output of the i-th vav box and ts is the supply fig. . vav based hvac system air temperature. then, the first law of thermodynamics applied to each zone is ci dti dt = ṁicp (ts − ti) − rexti (ti − toa) − n∑ j= ,j �=i rij (ti − tj) + qi ( ) where ci is the thermal capacitance of zone i, rij = rji is the thermal resistance between zone i and zone j and rexti is the thermal resistance between zone i and the exterior of the building. toa is the outside temperature and qi is the heat flux due to occupancy and electronic devices. linearized model from ( ) is discretized using euler method with a sampling period ts and leads to written in general form as, hi(xi, xj, ui) = aixi + n∑ j= ,j �=i aijxj + biui + giw + qi ( ) where state xi is the zone temperature ti, input ui is the supply air flowrates ṁi and w as the outside temperature. . system decomposition the decomposition of the large scale system into the subsystems is one of the key problem addressed in the distributed control literature. we propose an approach based on the global sensitivity of the system motivated by sobieski sobieszczanski-sobieski ( ). he suggested to obtain the system sensitivity equations to evaluate the internal couplings and system behavior related to variable changes. this approach has been used for distributing the computing task of mathematical model design into various engineering disciplines in the s, especially for the aircraft wing design problems. in this work, this notion is extended to decompose the large scale system into the subsystems. the proposed decomposition approach based on the sensitivity analysis is briefly explained in the following sections. . sensitivity matrix the sensitivity equations are the partial derivatives of the system outputs with respect to the independent inputs. it is clear that if thermal balance for i-th zone as shown in ( ) is simplified, it represents the change in zone temperature with respect to the inputs as supply flow rate, supply air temperature and temperatures of the neighboring zones. for example, the coefficients aij in ( ) represents the sensitivity of the i-th zone temperature with respect to j-th zone temperature. the values of the coefficients bi ifac nmpc madison, wi, usa, august - , represents the sensitivity of i-th temperature zone with respect to the i-th input (ui). note that inputs from the neighboring zones (uj) will affect the the i-th zone temperature through j-th zone temperature (xj). this will be accounted in the coefficient aij. we write the thermal balance equations ( ) for all the zones and represent them in matrix form as follows, sgs =   h h ... hn− hn x ∂h ∂x ∂h ∂x . . . ∂hn− ∂x ∂hn ∂x ... ... ... ... ... ... xn ∂h ∂xn ∂h ∂xn . . . ∂hn− ∂xn ∂hn ∂xn u ∂h ∂u ∂h ∂u . . . ∂hn− ∂u ∂hn ∂u ... ... ... ... ... ... un ∂h ∂un ∂h ∂un . . . ∂hn− ∂un ∂hn ∂un   ( ) where the i-th column represents hi denoting the thermal balance for i-th zone. the rows represent the variables with respect to which the sensitivity is calculated. this sensitivity matrix contains the information about the system couplings with the states and the inputs. the following section explains the methodology to exploit this information in the system decomposition. the off-diagonal coefficients in this block matrix represent the degree of the sensitivity of the state variables x (x , . . . , xn) with respect to other state variables and inputs u (u , . . . , um). the basic idea behind the decomposition is to partition the matrix ( ) into p block diagonal form. every block will represent the group of zones representing a subsystem. the methodology of the matrix partition ensuring the minimal loss of information is explained in detail in the next section. . partitioning based on sensitivity the sensitivity matrix obtained in ( ) is a large scale sparse matrix. there are various methods proposed in the literature to transform a sparse matrix into the block diagonal form (golub and loan, ; pothen and fan, ). in this work, we use the nested � decomposition method (siljak, ). this method is based on the graph theory and is very popular in the matrix decomposition literature. in this method, matrix coefficients that are less than � are replaced by zeros. then, the modified matrix is reordered to obtain a block diagonal form. often, this procedure is carried out iteratively by augmenting � such that (�k < �k+ ) where k represents the iteration till the block diagonal form is achieved. let s�kgs be the matrix after eliminating matrix elements less than �k at k-th interval. this matrix s�kgs is permuted to obtain a diagonal form s �k gs using existing algorithms as e.g. reverse cuthill-mckee algorithms (golub and loan, ). to ensure minimal loss of the information in the modified sensitivity matrix s �k gs, ‖λev(sgs) − λev(s �k gs)‖ ≤ ‖λev(ζ)‖ ( ) where sgs is the sensitivity matrix sgs after applying the same permutation applied to the s �k gs. λev is used as the symbolic representation to denote eigenvalues of the matrix and ζ is the user defined tolerance matrix. the condition ( ) should be verified for each iteration. the detailed procedure of the decomposition of sensitivity matrix into block diagonal form is stated in the algorithm . thus, the sensitivity analysis is extended to obtain p subsystems. note that these subsystems may share the states depending on the selection of the decomposition architecture. overlapping diagonal blocks represent cou- pled subsystems through shared states. contrary, non- overlapping diagonal blocks represent decoupled subsys- tem. to obtain, better results, it is possible to obtain the mixture of overlapping and non overlapping architectures. the proposed approach of dmpc is independent of the architecture of the decomposition due to the formulation discussed in next sections. after applying algorithm , we partition the building system into p groups containing highly coupled zones. let the i-th group h̄i contains ni zones, satisfying ∑p i= ni = n and ∑p i= h̄i = ∑n i= hi. algorithm decomposition of global sensitivity matrix input data: sgs,� , ζ result : sgs iterate : k = ( ) replace sgs(ij) by zero if sgs(ij) < �k ( ) permuting s�kgs system using sparse reverse cm meth- ods into the matrix s �k gs ( ) verify the condition ‖λev(sgs) − λev(s �k gs)‖ ≤ ‖λev(ζ)‖ is satisfied ( ) if matrix is still not close to the diagonal enough augment �k to �k+ and repeat step ( ) otherwise, identify overlapping/nonoverlapping sep- arable blocks from modified s�kgs matrix . cost function formulation the formulation of the cost function for the considered vav based hvac building systems include the following objectives (i) to minimize the economic operational cost, (ii) to maintain the thermal comfort in the zones and (iii) to generate smoother control signals by eliminating fluctuations to increase the actuator life-time. detailed for- mulation to achieve mentioned goals are explained below. . economic cost function economic cost function in the proposed model predictive control refers to the total cost of the energy consumed by the building components, mainly by the supply fan and a heating coils in the ahus. let j be the total cost for a time interval [t , tf ], jie = ∫ tf t (jh + jfan) dt ( ) where jh and jfan are the costs due to energy consumed by the heating coil and the supply fan in the ahu: ( ) energy cost at the heating coil. the power or heat transfer rate (q̇coil) in the ahu required at the ifac nmpc madison, wi, usa, august - , tejaswinee darure et al. / ifac papersonline - ( ) – represents the sensitivity of i-th temperature zone with respect to the i-th input (ui). note that inputs from the neighboring zones (uj) will affect the the i-th zone temperature through j-th zone temperature (xj). this will be accounted in the coefficient aij. we write the thermal balance equations ( ) for all the zones and represent them in matrix form as follows, sgs =   h h ... hn− hn x ∂h ∂x ∂h ∂x . . . ∂hn− ∂x ∂hn ∂x ... ... ... ... ... ... xn ∂h ∂xn ∂h ∂xn . . . ∂hn− ∂xn ∂hn ∂xn u ∂h ∂u ∂h ∂u . . . ∂hn− ∂u ∂hn ∂u ... ... ... ... ... ... un ∂h ∂un ∂h ∂un . . . ∂hn− ∂un ∂hn ∂un   ( ) where the i-th column represents hi denoting the thermal balance for i-th zone. the rows represent the variables with respect to which the sensitivity is calculated. this sensitivity matrix contains the information about the system couplings with the states and the inputs. the following section explains the methodology to exploit this information in the system decomposition. the off-diagonal coefficients in this block matrix represent the degree of the sensitivity of the state variables x (x , . . . , xn) with respect to other state variables and inputs u (u , . . . , um). the basic idea behind the decomposition is to partition the matrix ( ) into p block diagonal form. every block will represent the group of zones representing a subsystem. the methodology of the matrix partition ensuring the minimal loss of information is explained in detail in the next section. . partitioning based on sensitivity the sensitivity matrix obtained in ( ) is a large scale sparse matrix. there are various methods proposed in the literature to transform a sparse matrix into the block diagonal form (golub and loan, ; pothen and fan, ). in this work, we use the nested � decomposition method (siljak, ). this method is based on the graph theory and is very popular in the matrix decomposition literature. in this method, matrix coefficients that are less than � are replaced by zeros. then, the modified matrix is reordered to obtain a block diagonal form. often, this procedure is carried out iteratively by augmenting � such that (�k < �k+ ) where k represents the iteration till the block diagonal form is achieved. let s�kgs be the matrix after eliminating matrix elements less than �k at k-th interval. this matrix s�kgs is permuted to obtain a diagonal form s �k gs using existing algorithms as e.g. reverse cuthill-mckee algorithms (golub and loan, ). to ensure minimal loss of the information in the modified sensitivity matrix s �k gs, ‖λev(sgs) − λev(s �k gs)‖ ≤ ‖λev(ζ)‖ ( ) where sgs is the sensitivity matrix sgs after applying the same permutation applied to the s �k gs. λev is used as the symbolic representation to denote eigenvalues of the matrix and ζ is the user defined tolerance matrix. the condition ( ) should be verified for each iteration. the detailed procedure of the decomposition of sensitivity matrix into block diagonal form is stated in the algorithm . thus, the sensitivity analysis is extended to obtain p subsystems. note that these subsystems may share the states depending on the selection of the decomposition architecture. overlapping diagonal blocks represent cou- pled subsystems through shared states. contrary, non- overlapping diagonal blocks represent decoupled subsys- tem. to obtain, better results, it is possible to obtain the mixture of overlapping and non overlapping architectures. the proposed approach of dmpc is independent of the architecture of the decomposition due to the formulation discussed in next sections. after applying algorithm , we partition the building system into p groups containing highly coupled zones. let the i-th group h̄i contains ni zones, satisfying ∑p i= ni = n and ∑p i= h̄i = ∑n i= hi. algorithm decomposition of global sensitivity matrix input data: sgs,� , ζ result : sgs iterate : k = ( ) replace sgs(ij) by zero if sgs(ij) < �k ( ) permuting s�kgs system using sparse reverse cm meth- ods into the matrix s �k gs ( ) verify the condition ‖λev(sgs) − λev(s �k gs)‖ ≤ ‖λev(ζ)‖ is satisfied ( ) if matrix is still not close to the diagonal enough augment �k to �k+ and repeat step ( ) otherwise, identify overlapping/nonoverlapping sep- arable blocks from modified s�kgs matrix . cost function formulation the formulation of the cost function for the considered vav based hvac building systems include the following objectives (i) to minimize the economic operational cost, (ii) to maintain the thermal comfort in the zones and (iii) to generate smoother control signals by eliminating fluctuations to increase the actuator life-time. detailed for- mulation to achieve mentioned goals are explained below. . economic cost function economic cost function in the proposed model predictive control refers to the total cost of the energy consumed by the building components, mainly by the supply fan and a heating coils in the ahus. let j be the total cost for a time interval [t , tf ], jie = ∫ tf t (jh + jfan) dt ( ) where jh and jfan are the costs due to energy consumed by the heating coil and the supply fan in the ahu: ( ) energy cost at the heating coil. the power or heat transfer rate (q̇coil) in the ahu required at the ifac nmpc madison, wi, usa, august - , tejaswinee darure et al. / ifac papersonline - ( ) – heating coil to deliver an airflow at temperature ts is directly obtained from the energy conservation law q̇coil = n∑ i= ṁicp (ts − tmi) ( ) where tmi is temperature of air at the output of mixer. then, the energy cost due to heating is simply given by jh = c q̇coili ( ) where c represents the related energy cost per kwh. ( ) energy cost delivered for the mass airflow. the vavs require a certain total mass airflow depending on each local (zone) heating load. this mass airflow is discharged by the power fan which is driven by a variable speed drive. the power fan characteristics for the ahu is given by a cubic law, that is, ẇfan = α ( n∑ i= ṁi ) with the above power characteristics, the cost the energy for a supply fan is as follows, jfan = c ẇfani ( ) where c is corresponds to energy cost per kwh. thus, the total power demand from the ahu can be summarized from ( ), ( ) and ( ). note that j is a functional depending on the decision variables u, the state x and the disturbance d on [t , tf ]. in a discrete-time setting, the value of this integral ( ) during sampling interval [tk, tk+ ] for any k = , , ..., n is exactly given by ∫ tk+ tk jedτ = jik. then, we discretize je integral with euler method using sampling time h. hence the total economic cost for the building operation, �ek(u(k)) = c n∑ i= ui(k) + c n∑ i= ui(k) ( ) . thermal comfort to maintain the thermal comfort in the zones, the tem- perature should be controlled in the range of [xmin, xmax]. these bounds are relaxed to allow economic optimization, −ζ + xmin ≤ x(k) ≤ ζ + xmax ( ) where ζ is relaxation parameter with ≤ ζ ≤ . . hence, the magnitude of this relaxation parameter ζ is considered as optimization variable by adding a penalty term in the optimization problem defined by, �tck (ζ) = ζ ( ) . elimination of fluctuations in the control signal the above cost functions ( ) and ( ) considers the energy use and thermal comfort aspects. in addition, we introduce a term which indirectly addresses the maintenance cost. this is achieved by minimizing the variations in the control signal. hence, the smooth control signals reduces the fatigue in the actuators, lowering the system maintenance cost. this term is a regularization term that is formulated as one norm over a variation of control signal shown below, �rek (u(k)) = λ{‖u(k) − u(k − )‖ } ( ) where ui(k − ) is the the control input implemented at previous instant and λ is the regularization parameter with λ > . for more details, readers are refered to gallieri ( ) and darure et al. ( ). now, the total cost for the k-th instant can be expressed as j (u(k), x(k), ζ) = αe� e k(u(k)) + αtc� tc k (ζ) + αre� re k (u(k)) ( ) where αe, αtc and αre are the appropriate weights defined by the user. . sensitivity based cooperation in dmpc in the proposed dmpc, the coordination of the subsystem controllers is based on the sensitivity of the control actions with respect to the neighboring subsystem information. let us consider that optimization problem associated to the centralized mpc can be expressed as follows, minimize uk,xk,ζ jn (uk, xk, ζ) subject to h(xk, uk) = xmin ≤ xk ≤ xmax umin ≤ uk ≤ umax x (k| k) = x(k) ζ ≥ ( ) where uk = {u(k), . . . , u(k + n − )} and xk = {x(k + ), . . . , x(k + n)} are the sequences of predicted control inputs at time k. also, jn (uk, xk, ζ) is the cost function ( ) over the prediction horizon n. the bounds on the input vector u i.e. on the supply airflow rate [umin, umax] represent the damper limits in the vav box. the bounds on states [xmin, xmax] represent the soft bounds on the zone temperature to maintain thermal comfort. for better understanding of the proposed approach let us rewrite ( ) in simplified form as, j = minimize z φ(z) subject to h(z) = ( ) zmin ≤ z ≤ zmax z = [z , . . . , zn+m] where z = (x(k)k, u(k), ζ) and the function φ(z) corre- sponds to (jn) the overall cost over the prediction horizon n. using the decomposition approach presented in the sec- tion , we decompose the large scale system into the p sub- systems by grouping the highly coupled states (ĥn ..., ĥnp). let us formulate the sensitivity based optimization prob- lem for the i-th subsystem, ji = minimize zi φ(zi, z̄j) + { ∂φ ∂zi + p∑ k= k �=i ∂ĥk ∂zi } (zi − z̄i) subject to ĥi(zi) = zmini ≤ zi ≤ z max i ( ) zi = [z , . . . , zni] ifac nmpc madison, wi, usa, august - , where z̄i and z̄j are initial feasible values of the subsys- tems. note, this formulation will be valid irrespective of separability property of the overall cost function φ. as observed from this formulation, the cost function in- cludes the terms representing sensitivity of i-th subsystem with respect to j-th subsystems. from ( ), the lagrange function l is as follows, l(z) = φ(z) + n∑ k= λkhk(z) ( ) where λk are lagrange multipliers. now, the necessary condition of optimality in boyd ( ) for the lagrange function ( ) at initial feasible point (z̄, λ̄) is ∇l|z̄ = ∂φ(z) ∂z ∣∣∣ z̄ + λ ∂h(z) ∂z ∣∣∣ (z̄,λ̄) ( ) the sensitivity based dmpc formulation applied to ( ) allows the cost function for i-th subsystem be rewritten as follows φi(zi, z̄j) = φ(zi, z̄j) + p∑ j= j �=i { ∂φ ∂zi ∣∣∣ z̄j + λ̄j ∂ĥj ∂zi ∣∣∣ z̄j } (zi − z̄i) ( ) let the lagrange function for i-th subsystem be, li(zi) = φi(zi, z̄j) + p∑ j= j �=i λ̄jĥj(z) + λiĥi ( ) the necessary condition of the optimality of the i-th local subsystem mpc is given by, ∂φ(zi, z̄j) ∂zi + p∑ j= j �=i λ̄j ∂hj(zi, z̄j) ∂zi + λi ∂hi(zi, z̄j) ∂zi = i �= j now, necessary condition for optimization for all p sub- problems, p∑ i= p∑ j= j �=i ∂φ(zi, z̄j) ∂zi +λ̄j ∂hj(zi, z̄j) ∂zi +λi ∂hi(zi, z̄j) ∂zi = ( ) note that the necessary condition for the centralized problem ( ) and distributed problem ( ) are equivalent. this indicates that the solution obtained by mean of the centralized architecture and sensitivity based distributed architecture are the same. algorithm summarizes the method based on the problem formulation ( ), . simulation results in the benchmark building introduced in section , the occupants are present in the school in the working time i.e. from : to : . the study is carried out during the winter season at nancy in france. the plots of the heat flux due to occupancy and weather temperature over five workings days are shown in the figure . thermal balance equations ( ) are evaluated for every zone in the benchmark building. the data shown in table ( ) algorithm sensitivity based distributed model predic- tive algorithm initial data: ĥ,x k, u k,u max,umax,xmax,xmax, j ( ) solve the problem ( ) for all the subsystems at local level ( ) implement the solution u∗i (k) to the i-th subsystem ( ) obtain the measurements x(k) from the subsystems ( ) previous implemented control signals and measure- ments of states will be initial condition x k+ , u k+ for (k + )-th instant for each problem ( ) ( ) repeat step days h ea t f lu x (k w ) . heat flux due to occupancy days t em p (◦ c ) - weather temeperature fig. . disturbances ci . kj/s rext w/ ◦c rij w/ ◦c cp . kj/kg ◦c t oa ◦c t s ◦c ṁ i . m /s qi . kw t min ◦c t max ◦c ṁmin . m /s ṁmax . m /s t i ◦c n h table . numerical data values used for bench- mark building simulation is used in simulating the case study school building (tash- tousha et al., ). the sensitivity matrix ( ) is calculated and partitioned to obtain the subsystems as groups of zones. from the building layout presented in figure , we obtain two groups p = as { , , , } and { , , , }. the number of groups or partitions are decided by the user. applying algorithm , sensitivity based dmpc con- troller is simulated considering the obtained subsystems. to represent the performance of the implemented architec- ture, the temperature response and corresponding supply airflow for zone are shown in figure and figure , respectively. note that the thermal range and actuators limits can be different and is convenient to define the proposed distributed architecture. according to the convergence analysis presented in sec- tion , the performance of the sensitivity based dmpc is equivalent to the cmpc framework. this is verified from the temperature and supply airflow behavior of the re- spective control architectures. we also compare the control performance with decentralized mpc architecture (siljak, ). in decentralized mpc, subsystem controllers oper- ate independent of the state of the neighboring subsystems i.e. without any coordination or data exchange between ifac nmpc madison, wi, usa, august - , tejaswinee darure et al. / ifac papersonline - ( ) – where z̄i and z̄j are initial feasible values of the subsys- tems. note, this formulation will be valid irrespective of separability property of the overall cost function φ. as observed from this formulation, the cost function in- cludes the terms representing sensitivity of i-th subsystem with respect to j-th subsystems. from ( ), the lagrange function l is as follows, l(z) = φ(z) + n∑ k= λkhk(z) ( ) where λk are lagrange multipliers. now, the necessary condition of optimality in boyd ( ) for the lagrange function ( ) at initial feasible point (z̄, λ̄) is ∇l|z̄ = ∂φ(z) ∂z ∣∣∣ z̄ + λ ∂h(z) ∂z ∣∣∣ (z̄,λ̄) ( ) the sensitivity based dmpc formulation applied to ( ) allows the cost function for i-th subsystem be rewritten as follows φi(zi, z̄j) = φ(zi, z̄j) + p∑ j= j �=i { ∂φ ∂zi ∣∣∣ z̄j + λ̄j ∂ĥj ∂zi ∣∣∣ z̄j } (zi − z̄i) ( ) let the lagrange function for i-th subsystem be, li(zi) = φi(zi, z̄j) + p∑ j= j �=i λ̄jĥj(z) + λiĥi ( ) the necessary condition of the optimality of the i-th local subsystem mpc is given by, ∂φ(zi, z̄j) ∂zi + p∑ j= j �=i λ̄j ∂hj(zi, z̄j) ∂zi + λi ∂hi(zi, z̄j) ∂zi = i �= j now, necessary condition for optimization for all p sub- problems, p∑ i= p∑ j= j �=i ∂φ(zi, z̄j) ∂zi +λ̄j ∂hj(zi, z̄j) ∂zi +λi ∂hi(zi, z̄j) ∂zi = ( ) note that the necessary condition for the centralized problem ( ) and distributed problem ( ) are equivalent. this indicates that the solution obtained by mean of the centralized architecture and sensitivity based distributed architecture are the same. algorithm summarizes the method based on the problem formulation ( ), . simulation results in the benchmark building introduced in section , the occupants are present in the school in the working time i.e. from : to : . the study is carried out during the winter season at nancy in france. the plots of the heat flux due to occupancy and weather temperature over five workings days are shown in the figure . thermal balance equations ( ) are evaluated for every zone in the benchmark building. the data shown in table ( ) algorithm sensitivity based distributed model predic- tive algorithm initial data: ĥ,x k, u k,u max,umax,xmax,xmax, j ( ) solve the problem ( ) for all the subsystems at local level ( ) implement the solution u∗i (k) to the i-th subsystem ( ) obtain the measurements x(k) from the subsystems ( ) previous implemented control signals and measure- ments of states will be initial condition x k+ , u k+ for (k + )-th instant for each problem ( ) ( ) repeat step days h ea t f lu x (k w ) . heat flux due to occupancy days t em p (◦ c ) - weather temeperature fig. . disturbances ci . kj/s rext w/ ◦c rij w/ ◦c cp . kj/kg ◦c t oa ◦c t s ◦c ṁ i . m /s qi . kw t min ◦c t max ◦c ṁmin . m /s ṁmax . m /s t i ◦c n h table . numerical data values used for bench- mark building simulation is used in simulating the case study school building (tash- tousha et al., ). the sensitivity matrix ( ) is calculated and partitioned to obtain the subsystems as groups of zones. from the building layout presented in figure , we obtain two groups p = as { , , , } and { , , , }. the number of groups or partitions are decided by the user. applying algorithm , sensitivity based dmpc con- troller is simulated considering the obtained subsystems. to represent the performance of the implemented architec- ture, the temperature response and corresponding supply airflow for zone are shown in figure and figure , respectively. note that the thermal range and actuators limits can be different and is convenient to define the proposed distributed architecture. according to the convergence analysis presented in sec- tion , the performance of the sensitivity based dmpc is equivalent to the cmpc framework. this is verified from the temperature and supply airflow behavior of the re- spective control architectures. we also compare the control performance with decentralized mpc architecture (siljak, ). in decentralized mpc, subsystem controllers oper- ate independent of the state of the neighboring subsystems i.e. without any coordination or data exchange between ifac nmpc madison, wi, usa, august - , tejaswinee darure et al. / ifac papersonline - ( ) – days t e m p e ra tu re (° c ) temperature for zone days t e m p e ra tu re (° c ) temperature for zone days t e m p e ra tu re (° c ) temperature for zone days t e m p e ra tu re (° c ) temperature for zone days t e m p e ra tu re (° c ) temperature for zone days t e m p e ra tu re (° c ) temperature for zone days t e m p e ra tu re (° c ) temperature for zone days t e m p e ra tu re (° c ) temperature for zone fig. . temperatures response for all the zones days a ir fl ow (k g / s) . supply air flow rate for zone days a ir fl ow (k g / s) . supply air flow rate for zone days a ir fl ow (k g / s) . supply air flow rate for zone days a ir fl ow (k g / s) . supply air flow rate for zone days a ir fl ow (k g / s) . supply air flow rate for zone days a ir fl ow (k g / s) . supply air flow rate for zone days a ir fl ow (k g / s) . supply air flow rate for zone days a ir fl ow (k g / s) . supply air flow rate for zone fig. . supply airflow rates for all the zones the controllers. also, the dynamics of the subsystems in decentralized control architecture completely ignores the coupling with the neighboring subsystems. figure and the figure compares the performance of the all the control architectures. to support the previous conclusions, we also compare the energy consumed by the benchmark hvac building over the five working days in the figure . as, in the building system, the coupling between the zones are effective and if ignored, it results in consuming more energy and poor control performance. . conclusion in this work, we propose an approach that addresses the two stages of dmpc for the vav based hvac building system as i) the decomposition of the building system into subsystems and ii) the coordination between obtained subsystem controllers. both objectives are based on the basic notion of sensitivity analysis. the proposed criterion in the method of decomposing the system into subsys- tems ensures minimum loss of the information of system dynamics. the method of sensitivity based coordination among the subsystem controllers is discussed in detail. the convergence analysis of the proposed method suggests days . . . . . e n e rg y c o n su m p ti o n (k w ) . . . energy consumtion decentralized centralized distributed fig. . energy consumption that the performance of the sensitivity based dmpc is equivalent to the cmpc performance. the decomposition and coordination strategies are demonstrated on the vav based hvac building. the method can be adapted to different systems regardless of the separability of the cost function and the couplings between the subsystems. future work will be focused for possible extension for the nonlinear systems and other types of hvac buildings applications. references afram, a. and janabi-sharifi, f. ( ). theory and applications of hvac control systems. building and environment, , – . boyd, s. ( ). convex optimization. stanford univer- sity, usa. darure, t., yamé, j.j., and hamelin, f. ( ). total variation regularized eco- nomic model predictive con- trol applied to a multizone building. in th inter- national conference on control, automation, robotics and vision (icarcv). phuket, thailand. eu ( ). eu-energy efficiency for buildings. https://ec.europa.eu/energy/en/topics/energy- efficiency/buildings. gallieri, m. ( ). lasso-mpc predictive control with l -regularised least squares. ph.d. thesis, university of cambridge uk. golub, g. and loan, c. ( ). matrix computation. johnson hopkins university press baltimore. lamoudi, m. ( ). distributed model predictive control for energy management in buildings. ph.d. thesis, university of grenoble france. pothen, a. and fan, c.j. ( ). computing the block triangular form of a sparse matrix. acm transactions on mathematical software, , – . siljak, d.d. ( ). decentralized control of complex systems. new york, academic press. sobieszczanski-sobieski, j. ( ). on the sensitivity of complex and internally coupled systems. technical report, nasa technical memorandum. tashtousha, b., molhim, m., and al-rousan, m. ( ). dynamic model of an hvac system for control analysis. energy, ( ), – . ifac nmpc madison, wi, usa, august - , slavic review matical programming and tolerances in planning," economic computation and economic cybernetics studies and research [bucharest], , no. , pp. - ). this treatise offers an abstract framework to contain the diverse realities of the economic systems around us. the challenge now is to fill the intervening space, work- ing up from empirical detail and down from strict theory, to build a tested body of understanding. contributions to the effort may well appear in the new journal of com- parative economics whose editor, not surprisingly, is john michael montias. holland h u n t e r haverford college t r e n d s in t h e s o v i e t o i l a n d gas i n d u s t r y . by robert w. camp- bell. a resources for the future book. baltimore and london: the johns hop- kins university press, . xvi, pp. tables. figures. $ . . this compact, succinct little book is a useful companion to the author's economics of soviet oil and gas ( ). it admirably fulfills the stated intentions of updating the data base of the earlier work and reviewing the most important developments since . separate chapters deal with soviet energy policy, exploration, drilling, oil pro- duction, oil transport, oil refining, the gas industry, the economic reform in oil and gas, and soviet participation in world energy markets (as buyer and seller). in cogent summaries that bracket the more detailed discussion, professor campbell argues that soviet oil and gas planners now face problems different from those of the s and s, and that their success in dealing with these problems will determine both the level and structure of future soviet energy development. as usual, careful scholarship routs glib generalizations—for example, the undue pessimism about a soviet "energy crisis," and the undue optimism that the u s s r can bail the west out of its own energy crisis with massive energy exports. professor campbell attributes many of the problems soviet energy planners face to difficulties in meeting technological challenges—in drilling, oil refining, pipeline construction and operation, and the production of both oil and gas. this line of argu- ment is backed up by a wealth of technical detail. insightful (if tantalizingly brief) discussions deal with refinery mixes and product quality, the utilization of natural gas, the export of crude oil versus refined products, and planning methods (especially the attempts to apply optimizing models). in view of the apparent space constraints, soviet oil purchases in the middle east receive overmuch attention, with perhaps the least satisfying results. (arms sales and comecon debt instruments are stressed, to the relative neglect of the desire to minimize transport costs, given fixed commitments to communist allies—to the reviewer, the best explanation of those purchases.) unfortu- nate publication delays have left the data series two or three years out of date, in a situation subject to rapid change. not to carp, however—this is a valuable book for serious students of soviet energy policy and more general readers alike. a r t h u r w. w r i g h t purdue university t h e c l i m a t e s o f t h e s o v i e t u n i o n . by paul e. lydolph. world survey of climatology, vol. . amsterdam and new york: elsevier scientific publishing company, . xii, pp. illus. dfl. . $ . . dr. lydolph has performed a valuable and long overdue service in compiling a com- prehensive reference on climatic factors in the soviet union. his stated intent "is to present general climatic information that can be used as a basis for other studies which filling potholes on the path to fusion pores new and notable filling potholes on the path to fusion pores barry r. lentz,* david p. siegel,† and vladimir malinin‡ *molecular and cellular biophysics, department of biochemistry and biophysics, university of north carolina at chapel hill, north carolina, †givaudan inc, cincinnati, ohio, and ‡elan pharmaceuticals, princeton, new jersey usa membrane fusion is at the heart of eukaryotic cell life. carefully regu- lated membrane fusion is required for cell compartmentalization, for the im- port of large molecules into the cell, and for the export both of waste mol- ecules and of signaling molecules that carry information to other cells in a community. the complex cellular ma- chinery that carries out these functions is beginning to come into focus (brunger, ), but a detailed molec- ular view of how these machines work on membrane lipid bilayers to accom- plish a change in topology of cellular compartments is still lacking. the dif- ficulty in dissecting this process lies not just in the complexity of the ma- chines, but also in the task of defining experimentally a dynamic process op- erating in a semi-ordered system such as the lipid bilayer. although experi- mental approaches are available, it has been popular for some time to treat this problem theoretically, in terms of sim- ple models in which complex arrange- ments of lipid molecules are treated in terms of the material properties of ar- rays of lipid molecules as they occur in macroscopic semicrystalline lipid phases. although this is clearly a vast simplification, it is probably, if prop- erly parameterized, a useful zeroth or- der approach to the very difficult prob- lem of estimating the free energies of presumed intermediates on the molec- ular path to fusion. the widely accepted model for this process derives from the original pro- posal that two bilayers brought into close contact can merge their contact- ing (cis) monolayers in a torroidal “stalk” that joins half the lipid compo- nents of the two original bilayers (fig. b from markin and albanesi ( )). the distal (trans) monolayers of this structure are not merged, which pre- vents continuity between the trapped aqueous compartments of the two fus- ing membranes. this has been termed the stalk hypothesis (markin et al., ). later, it was recognized that the stalk may exist in two different forms, an initial stalk and a transmembrane contact (siegel, ). it was univer- sally accepted that such structures must have a free energy substantially larger than that of the lipid bilayers from which it was proposed to arise. a systematic estimate of this energy was first made in terms of two major con- tributions: the energy associated with bending planar monolayers into toroids, and the interstice (“void”) en- ergy associated with the junctions where monolayers are peeled away from one another (siegel, ). the latter was, in the initial level of ap- proximation, estimated as proportional to the surface area of the interface be- tween lamellar structures and a hypo- thetical void that represented the space unfilled by uniformly packed mono- layers distorted to match the hypothe- sized nonlamellar stalk structure (sie- gel, ). the bending energy was estimated in terms of the free energy required to distort a uniform lamellar monolayer from its spontaneous or “in- trinsic” curvature to match the as- sumed stalk shape. the energy of the void was parameterized based on the properties of the phase transition from a lamellar to a nonlamellar phase (hex- agonal phase) that was also viewed as composed of bent lamellar structures and voids. based on this treatment, the free energy of the stalk was estimated to be so large (� kt) that there has been question as to whether such a structure could be part of the fusion process, although these calculations suggested that the stalk was the lowest- energy intermediate of several pro- posed fusion mechanisms (siegel ). thus, the stalk hypothesis was found to face an “energy crisis.” two papers appear in this month’s issue of the biophysical journal (ko- zlovsky and kozlov, ; markin and albanesi, ) that, along with an- other recent paper (kuzmin et al., ), propose solutions to this energy crisis. markin and albanesi ( ) propose that the assumption of circular torroidal geometry for the stalk pro- duced too large a bending energy. these authors show that it is possible to relax this assumption and define, in terms of two geometric parameters, a stress-free stalk that has the same av- erage intrinsic curvature as the lipid mixture of which it is composed. just as for the original stalk hypothesis (markin et al., ; siegel, ), one can question some of the geometric assumptions of this calculation. how- ever, it is a reasonable result that the bending energy of a geometrically re- laxed stalk can be reduced signifi- cantly from the original estimate that was based on a rigid (circular torroid) geometry. even if the bending free en- ergy of the stalk can be reduced to zero, the interstice or void free energy attributable to the intrinsic geometric mismatch between lamellar and nonla- mellar lipid structures must persist. this is variously estimated as several tens of kt, still a formidable energy but much less imposing than the earlier estimates of the stalk energy. the other two articles both ask whether it is appropriate to estimate the interstice energy in terms of the surface of the interface between a void and smoothly bent lamellar structures. submitted december , , and accepted for publication december , . © by the biophysical society - / / / / $ . biophysical journal volume february – although it is unlikely that a true mac- roscopic void exists in intermediate structures leading to fusion, this con- struct was originally used as a self- consistent and convenient way to esti- mate the free energy associated with the inherent nonlamellar nature of the stalk (siegel, ). the question is whether a better method exists for es- timating this free energy. kozlovsky and kozlov ( ) and kuzmin et al. ( ) both argue that this energy is better estimated in terms of the energy needed to bend lamellar structures so sharply that they accommodate the in- herently nonlamellar nature of the pro- posed stalk structure. this requires tilt of individual lipid molecules and must occur at an energy price, as tilting lipid molecules relative to the bilayer nor- mal expose their hydrophobic regions to water and elongate acyl chains. sim- ilar to the void energy, the tilt defor- mation energy can be estimated from experimental data on phase transitions of lipid liquid crystals from lamellar- to-nonlamellar states. kozlovsky and kozlov ( ) use the tilt approach to treat the deforma- tion of monolayers in terms of a com- bination of splay (monolayer bending and/or tilt gradient) and uniform tilt of lipid molecules away from the local monolayer normal. the “tilt” formal- ism provides a means to account for the interstice energy without the as- sumption of a void. figure by mar- kin and albanesi illustrates this ap- proach relative to the traditional void approach. kozlovsky and kozlov de- scribe the stalk in terms of two geo- metric parameters (width of the stalk base, interbilayer distance). this ap- proach yields a minimum free energy for the stalk at an intrinsic curvature of � . nm� of – kt, which is ap- proximately the same as one would estimate for the interstice energy based on the void model, as pointed out by markin and albanesi. curiously, at in- trinsic curvatures of � � . nm� , the stalk of kozlovsky and kozlov be- comes thermodynamically stable rela- tive to planar bilayers. in summary, one essential finding of both teams markin/albanesi and ko- zlovsky/kozlov is that the energy re- quired to deform the monolayers into a stalk is substantially lower than calcu- lated with the approach used previ- ously. basically, the source of the overestimate in previous models was the use of a simplistic geometric model. both sets of authors show that a more realistically shaped stalk is likely to have considerably lower bending energy, which, relative to planar bilay- ers, can even become negative for bi- layers of substantial negative intrinsic curvature. however, it seems that the interstice free energy still dominates the stalk free energy and we may still have to fill the potholes in the pathway to fusion pores. there are tough problems that re- main to model successfully the mech- anism of fusion. in both these manu- scripts, the authors calculate only the lower bound to the true activation en- ergy for formation of fusion interme- diates. present models account only for the energy of intermediates viewed as static structures. experimentally, the process of converting closely contact- ing membranes (initial static structure) to a fusion pore (final static structure) involves at least three kinetic steps and two intermediates (lentz et al., ). the first and last of these steps involve changes in the topology of membranes and trapped compartments and thus de- mand dramatic rearrangements of lipid and water molecules. these are not likely to find description by the sort of continuum, macroscopic theories re- viewed here, although some attempts have been made to do so (kuzmin et al., ; markin and albanesi, ). the second step, interconversion of fu- sion intermediates, probably does not require changes in topology and may be amenable to such an approach. nor have we really addressed the problem of how two membranes become dis- torted and so closely apposed that the initial conversion to a fusion interme- diate can occur. most importantly, ex- perimental tests of these models need to be devised. given the highly local- ized and dynamic nature of membrane fusion events, this will be very diffi- cult. however, the same rules that gov- ern the relative energies of different- geometry intermediates must also apply to the relative free energies of lipid molecules in lamellar and nonla- mellar phases. therefore, it is probably worth some effort to see which of the new proposals best describes the rela- tive stability and formation kinetics of complex lipid assemblies such as in- verted cubic phases. clearly there is much lipid physical chemistry that re- mains to be done! how do these new results help us understand the process of protein-in- duced membrane fusion? first, the res- olution of the energy crisis increases our confidence that structures such as stalks do represent low-energy path- ways to membrane fusion. second, the dominant nature of the void or inter- stice energy suggests that we look to how parts of fusion proteins that reside in or interact with membrane bilayers might lower this free energy. this will require combinations of experimental and theoretical approaches. in doing so, it is appropriate to keep in mind that the stalk hypothesis is an hypoth- esis and that the actual mechanism of biomembrane fusion may be even more complex than suggested by this model. references brunger, a. t. . structural insights into the molecular mechanism of calcium-dependent vesicle-membrane fusion. curr. opin. struct. biol. : – . kozlovsky, y., and m. m. kozlov. . stalk model of membrane fusion: solution of energy crisis. biophys. j. : – . kuzmin, p. i., j. zimmerberg, y. a. chiz- madzhev, and f. s. cohen. . a quantita- tive model for membrane fusion based on low-energy intermediates. proc. natl. acad. sci. u.s.a. : – . lentz, b. r., v. malinin, m. e. haque, and k. evans. . protein machines and lipid assemblies: current views of cell membrane fusion. curr. opin. struct. biol. : – . markin, v. s., and j. p. albanesi. . mem- brane fusion: stalk model revisited. biophys. j. : – . lentz et al. biophysical journal ( ) – markin, v. s., m. m. kozlov, and v. l. borov- jagin. . on the theory of membrane fu- sion. the stalk mechanism. gen. physiol. bio- phys. : – . siegel, d. p. . energetics of intermediates in membrane fusion: comparison of stalk and inverted micellar intermediate mechanisms. biophys. j. : – . siegel, d. p. . the modified stalk mecha- nism of lamellar/inverted phase transitions and its implications for membrane fusion. biophys. j. : – . fusion pores biophysical journal ( ) – global journal of advanced engineering technologies and sciences [okoye et al., ( ): november, ] issn - impact factor . http: // www.gjaets.com/ © global journal of advance engineering technology and sciences [ ] global journal of advanced engineering technologies and sciences a study and analysis of energy generation and consumption in dangote cement plant, ibese, ogun state, nigeria okoye, c. u., bitrus, i, alao, m. j., adelakun, n. o. & abdulhamid, i. g. * department of electrical / electronic engineering the federal polytechnic, ilaro, ogun state, nigeria. corresponding author: okoye, c. u. doi: . /zenodo. abstract energy supply for economic activities has been a major problem in nigeria such that it does appear that solution to stable, reliable power supply is not yet in sight. consequently, consumers (industrial, residential and commercial) have all resorted to self-generation to complement whatever supply (if any) that comes from the very unreliable national grid. for instance, the available power supply to the entire nation fluctuates between mw and mw. a study of monthly energy generation in dangote cement plant for a typical year was carried out. this was compared with the equivalent monthly generation from the entire nigeria’s grid system. the results show that in , at the early stage of commencement of production of operation in the plant), the total energy generated by the dangote power plant was . mwh while the total energy consumed by the company was . mwh. dangote’s total energy generation in represents . % of nigeria’s total generation from grid in the same year. the total distribution loss was . mwh (which is . % of the total energy generated by the company).comparatively, the total generation from national grid in was . this study further shows that dangote cement, ibese produces enough energy for its use and could even sell any excess if encouraged. keywords: national grid, self-generation, consumers, dangote cement, independent power producer. introduction electrical energy is the main component of energy which humankind uses for comfort and to perform other useful economic activities. just as human beings require oxygen to survive, a nation needs sufficient energy if she must have meaningful development. that is why nations of the world today go far enough to exploit nature, tap its resources and convert them to electrical energy (alamau, ). the developed countries such as u.s.a, france, germany and britain (among others) invest massively in energy development and thus are able to bring good things of life to their people. developing countries remains backward in development because they have poor energy infrastructure. consequently, their industries (where they exist) perform very poorly. in nigeria, many industries are known to have closed down. a lot more may be on the verge of closing down; all for lack of electricity / power. according to adinuba ( ) about multi-national industries such as michelin, dunlop, glaxo and pfizer have relocated to ghana and elsewhere. before constructing its own gas-powered power plant. dangote cement, ibese was said to spend n million daily on diesel (ait, ). all this has contributed to the threatening unemployment in nigeria with associated crimes. besides, according to undp ( ), nigeria’s human development index in many aspects of human life has continued to decline. thus, the independent power producer (ipp) like dangote’s, if studied and evaluated could encourage persons interested in energy development to model it towards improving energy availability and reliability in nigeria. literature review according to otenaike ( ) and frn ( ), nigeria has abundant energy resources. for instance, the country has crude oil, natural gas and coal / lignite reserves of . billion barrels, trillion standard cubic feet (scf) and . billion tons respectively. this is in addition to large hydropower ( , mw), and small hydropower ( mw) reserves, and other resources such as solar, wind and biomass. the generating units in nigeria’s power stations consist of thermal and hydro. as at december , (ncc, ) the installed capacity of all thermal units was , mw while that of hydro was . mw. this makes it a ratio of % hydro and % thermal. the nation’s total installed capacity was , . mw. http://www.gjaets.com/ [okoye et al., ( ): november, ] issn - impact factor . http: // www.gjaets.com/ © global journal of advance engineering technology and sciences [ ] table . shows the independent power producers (ipps) connected to national grid as at december, . table . : independent power producers’ contributions to nigeria’s grid as at december, . source: national control centre, osogbo, nigeria. the ipps constituted mw (or . %) of the country’s total installed capacity. dangote cement plant, ibese generates electricity at kv for use in the plant using natural gas. natural gas is abundant, cheap and locally available in nigeria. methodology the required data were collected by undertaking some educational visits to dangote cement plant at ibese, ogun state, nigeria. ibese lies on latitude  ’ ” north and longitude  ’ ” east. the geology of the town and its environs comprises some formation which is marine and of paleocene age. limestone several meters in thickness overlain by a shale unit almost three times as thick as the limestone is found in the area (ayedun et al, ). additional data were also collected from the national control centre, (ncc), osogbo, nigeria and more from relevant literature. key areas covered include:  monthly energy generated and consumed in dangote cement plant, ibese, (jan – dec., ).  energy generation from grid (jan – dec., ).  installed and available capacities of the various independent power producers (ipps) connected to national grid (as at december, ).  daily energy generated and consumed in a typical month in dangote cement, ibese, (june, ). unfortunately, dangote plant ibese could not release data on energy generation and consumption for current years (probably due to company policy). results and discussion table . : energy generated and energy consumed in dangote cement plant, ibese, nigeria. in mwh ( ) month total energy generated (mwh) total energy consumed (mwh) difference between energy generated and consumed (mwh) differences (%) january . february . march . . . . april . . . . may . . . . june . . . . s/n power plant (station) installed capacity (mw) average availability (mw) rivers ipp . . omoku . . asco . . trans - amadi . . okpai . . ibom . . afam vi . . paras . . a.e.s. . . total . . http://www.gjaets.com/ [okoye et al., ( ): november, ] issn - impact factor . http: // www.gjaets.com/ © global journal of advance engineering technology and sciences [ ] july . . . . august . . . september . . . october . . . . november . . . . december . . . . grand total = . . . . source: dangote cement plc. note: differences in % = 𝐷𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒 (𝑀𝑊𝐻) 𝑇𝑜𝑡𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑒𝑑 (𝑀𝑊𝐻) 𝑥 % from table . , the difference between energy generated and energy consumed represents energy loss. the energy loss ranges from . percent to . percent. table . . scenario is illustrated graphically in fig. . , fig . , and fig. . . respectively. table . : energy generated from national grid and dangote cement plant, (jan – dec. ) month energy generated from national grid (mwh) a energy generated by dangote plant b % of energy generated by dangote plant 𝑪 = 𝑩 𝑨⁄ january . . february . . march . . . april . . . may . . . june . . . july . . . august . . . september . . . october . . . november . . . december . . . annual total . . . in table . , energy from nigeria’s national grid is compared with energy generated by dangote, ibese, plant. the relevant percentages by month are shown. this shows an appreciable effort by dangote because, for instance, in june , dangote plant, ibese, produced . % of energy from the grid in the same month. the same deduction could be made for the rest of the months. http://www.gjaets.com/ [okoye et al., ( ): november, ] issn - impact factor . http: // www.gjaets.com/ © global journal of advance engineering technology and sciences [ ] figure . : graphical illustration of total energy generated & energy consumed, (mwh) figure . : bar chart depicting total energy generated & energy consumed, (mwh) e n e rg y g e n e ra te d & e n e rg y c o n su m e d ( m w h ) total energy generated (mwh) total energy consumed (mwh) e n e rg y g e n e ra te d & e n e rg y c o n su m e d ( m w h ) total energy generated (mwh) total energy consumed (mwh) http://www.gjaets.com/ [okoye et al., ( ): november, ] issn - impact factor . http: // www.gjaets.com/ © global journal of advance engineering technology and sciences [ ] table . : total energy generated and total energy consumed in mwh (dangote plant, ibese, ). total energy generated (mwh) by dangote, plant total energy consumed (mwh) in dangote, ibese. . . source: dangote cement plc. figure . : the percentage of total energy generated & energy consumed, (mwh) table . : total energy generated from national grid and energy generated from dangote cement plant, ibese, nigeria in mwh month energy generated from national grid (mwh) in energy generated from dangote plant (mwh) energy from dangote as a percentage of total energy from grid (%) annual total . . . total energy generated (mwh) . % total energy consumed (mwh) . % total energy generated (mwh) total energy consumed (mwh) http://www.gjaets.com/ [okoye et al., ( ): november, ] issn - impact factor . http: // www.gjaets.com/ © global journal of advance engineering technology and sciences [ ] figure . : the percentage of total energy generated from grid & energy generated from dangote plant, in table . : daily energy generated and energy consumed in a typical month. (june, ) in dangote plant, ibese. days total energy generated (mwh) total energy consumed (mwh) -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . energy generated from national grid (mwh) . % energy generated from dangote plant (mwh) . % energy generated from national grid (mwh) energy generated from dangote plant (mwh) http://www.gjaets.com/ [okoye et al., ( ): november, ] issn - impact factor . http: // www.gjaets.com/ © global journal of advance engineering technology and sciences [ ] -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . -jun- . . source: dangote cement plc. figure . : graphical illustration of total energy generated & energy consumed in (mwh) in fig . , observe that losses were minimal and there was a drop in energy generation and consumption in june , . -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - -j u n - t o ta l e n e rg y g e n e ra te d & t o ta l e n e rg y c o n su m e d ( m w h ) days (june) total energy generated (mwh) total energy consumed (mwh) http://www.gjaets.com/ [okoye et al., ( ): november, ] issn - impact factor . http: // www.gjaets.com/ © global journal of advance engineering technology and sciences [ ] figure . : bar chart depicting energy generated & energy consumed by day in june (mwh) at dangote plant, ibese. conclusion energy generation and consumption has been studied and analysed for months of january to december, . also, the daily energy generation and consumption in the factory for a typical month (june, ) was also analysed. the industry was willing to release energy data for the year only. similarly, energy generation data collected from the national control centre (ncc), osogbo, nigeria for were analysed and compared to those from the dangote, ibese, power plant. from the study, it could be said that the power plant at dangote cement, ibese, is performing well. it generated a total energy of . mwh in which when compared with . mwh generated by the grid represents . percent of nigeria’s total energy generation for the year ( ). this is significant in a country facing serious energy crisis. also, dangote can generate surplus energy (more than the industry can use). besides, there was very minimal energy loss ( . %) as there was very little difference between energy generated and consumed. thus, the efficiency of energy transformation was high. recommendation  the exhaust heat from the dangote power plant is wasted. it can rather be used in heating and cooling through chiller, boiler and other industrial processes and operations.  dangote plant has the potential for generating and selling electricity to other consumers via the grid. the industry should therefore be encouraged.  electricity generation in nigeria is largely dependent on natural gas. no electricity is generated from coal, though coal is available in large quantity locally. the coal – fired power station in oji, enugu state, nigeria has been dead for long. coal should be exploited for electricity generation in the face of nigeria’s energy crisis. (okoye, ) references [ ] adinuba, c. d. ( , march ), electricity: how jonathan is punishing igboland, sunday sun, p. . [ ] ait ( ), african independent television, newspaper review, august . [ ] alamau ( ), african energy commission: accelerating africa’s economic growth through efficient energy production. http://www.gjaets.com/ [okoye et al., ( ): november, ] issn - impact factor . http: // www.gjaets.com/ © global journal of advance engineering technology and sciences [ ] [ ] ayedun, h., oyede, r. t., osinfade, b. g., oguntade, b. k., umar, b. f. & abiaziem, c. v. ( ). groundwater quality around new cement factory, ibese, ogun state, african journal of pure and applied chemistry. vol. , no. , [ ] frn ( ), federal republic of nigeria, investment opportunities in the nigerian power sector. [ ] ncc ( ), grid operations: annual technical report, national control centre, osogbo, nigeria. [ ] okoye, c. u. ( ), enhancing electricity generation capacity in africa through revamping coal – fired power plants: a case study of nigeria, paper presented at the th anniversary international conference of commonwealth association of technical universities and polytechnics in africa (capa) held in abuja, august – sept , . [ ] otenaike, s. & onifade, g. ( ), coal as a source of electricity generation in nigeria, the consulting engineer, may – august, vol. , no. . [ ] undp ( ), united nations development programme, human development report. http://www.gjaets.com/ energy-crises in well-aerated and anoxic tissue: does tolerance require the same specific proteins and energy-efficient transport? energy-crises in well-aerated and anoxic tissue: does tolerance require the same specific proteins and energy-efficient transport? hank greenwaya,c and william armstrong a,b aschool of plant biology, faculty of science, the university of western australia, crawley, wa , australia. bbiological science, school of environmental sciences, faculty of science and engineering, university of hull, kingston upon hull, hu rx, uk. ccorresponding author. email: hank.greenway@uwa.edu.au abstract. many of the profound changes in metabolism that are caused by o deficiency also occur in well-aerated tissues when oxidative phosphorylation is partially or wholly inhibited. for these well-aerated tissues, reduction in energy formation occurs during exposure to inhibitors of oxidative phosphorylation, cold/chilling and wounding, so we prefer the term ‘energy crisis’ metabolism over ‘anaerobic’ metabolism. in this review, we note that the overwhelming body of data on energy crises has been obtained by exposure to hypoxia-anoxia, which we will indicate when discussing the particular experiments. we suggest that even transient survival of an energy crisis requires a network of changes common to a large number of conditions, ranging from changes in development to various adverse conditions such as high salinity, drought and nutrient deficiency, all of which reduce growth. during an energy crisis this general network needs to be complemented by energy specific proteins, including the so called ‘anaerobic proteins’ and the group of erfvii transcription factors, which induces the synthesis of these proteins. crucially, the difference between anoxia-intolerant and -tolerant tissues in the event of a severe energy crisis would mainly depend on changes in some ‘key’ energy crisis proteins: we suggest these proteins would include phytoglobin, the v-h+ppiase and pyruvate decarboxylase. a second characteristic of a high tolerance to an energy crisis is engagement of energy efficient transport. this feature includes a sharp reduction in rates of solute transport and use of energy-efficient modifications of transport systems by primary h+ transport and secondary h+-solute transport systems. here we also discuss the best choice of species to study an energy crisis. further, we consider confounding of the acclimative response by responses to injury, be it due to the use of tissues intolerant to an energy crisis, or to faulty techniques. additional keywords: atp, hypoxia, inhibitors of oxidative phosphorylation, phcyt, ‘anaerobic’ enzymes, key proteins. received august , accepted february , published online april this review is arranged in two main parts, the first dealing with physiological aspects of ‘anaerobic metabolism’ induced in well-aerated tissues, the second with genetical aspects covering severe hypoxia-anoxia and the possible reasons for the multitude of changes in transcripts and enzymes in molecular studies. supplementary material provided includes a table of useful definitions. physiology: induction of ‘anaerobic metabolism’ in well-aerated tissues the main themes of this part of the review are: energy crisis metabolism in well-aerated tissues, phcyt during an ‘energy crisis’, reductions in energy charge and atp concentrations, and reductions in trans-membrane transport which embraces the use of energy efficient transporters and the calamitous effect of sugar starvation during an energy crisis. preamble this section presents evidence that so called ‘anaerobic metabolism’ can also be induced in well-aerated tissues by inhibitors of oxidative phosphorylation, cold temperatures, pi deficiency and wounding. all of these treatments do, or are likely to, reduce energy production. the evidence for development of energy deficient metabolism in well-aerated tissues is still not by any means as comprehensive as for o deficiency. once confirmed, the appropriate term for this syndrome would be ‘energy-deficient metabolism’ or ‘energy-crisis metabolism’ rather than ‘anaerobic metabolism’. note also that o at kpa in the boundary layer around a tissue/organ does not guarantee adequate o for all cells within. there may be high resistances in any internal supply pathway leading to steep concentration gradients in o and limited o availability both along and internal to these resistances. a gradient does not increase availability but is a reflection of both resistance and csiro publishing functional plant biology, , , – evans review https://doi.org/ . /fp journal compilation � csiro www.publish.csiro.au/journals/fpb mailto:hank.greenway@uwa.edu.au usage and with o availability reducing progressively down the gradient (armstrong et al. ; armstrong and armstrong ). the shift to an energy deficient metabolism probably originates with a decrease in atp concentrations, with increases in ca + levels in the cytoplasm and/or decreases in phcyt, changing among others activities of many enzymes. whether these three key factors always interact and/or act in concert is not certain. major components of energy crisis metabolism are less negative trans-membrane potentials, with decreases in rates of solute transport, reduced permeability of the plasma membrane and tonoplast, and engagement of energy-efficient transport systems across membranes. we confine ourselves mainly to energy crises caused by inhibition of oxidative phosphorylation. we do comment briefly on carbohydrate starvation during an energy crisis and suggest some characters would be relevant to the two types of energy crises, for example engagement of energy saving devices would be even more important during carbohydrate starvation during an energy crisis than when the carbohydrate supply was ample. this review is mainly confined to metabolism in the cytoplasm and to solute transport during an energy crisis. for other important aspects such as response to anoxia by mitochondria, return to air and h o formation see a recent review by shingaki-wells et al. ( ). in a separate paper (w. armstrong, t. d. colmer, p. m. beckett and h. greenway, unpubl. data) we will discuss formation of anoxic cores and the possible importance of the phytoglobin-nitric oxide cycle in atp formation during an energy crisis. this cycle may occur in shells surrounding anoxic cores, but also in well-aerated tissues when oxidative phosphorylation is inhibited. further aspects will be no and ethylene as possible messengers between different zones, or plant organs. energy crisis metabolism in well-aerated tissues in , dennis and co-workers suggested that the term ‘anaerobic response’ element involved in transcription of several anaerobic genes was a misnomer and was best replaced by: ‘energy deficiency regulatory element’. the hypoxic response element (hre; gibbs et al. ) is presumably the anaerobic response element discussed by dennis et al. and still does not cover energy crisis in fully aerated tissues. by extension, we suggest the term ‘energy-crisis metabolism’ may be better than the usually applied ‘anaerobic metabolism’. dennis et al. ( ) reached their conclusion mainly because transcripts of the ‘anaerobic’ enzyme, alcohol dehydrogenase (adh), could be induced, not only by o deficiency, but also by a range of adverse conditions in well-aerated tissues; listed were cold temperature (< �c) in tropical species, wilting, exposure to aba, , -d and wounding (dennis et al. ). based on this evidence for adh, they suggested that a single promoter element associated with anaerobic genes, initiated their transcription when mitochondrial function was reduced/inhibited. nie and hill ( ) also concluded that the induction of mrna of the ‘anaerobic’ protein phytoglobin is ‘not determined by oxygen availability, but rather by atp, or some consequence of atp action’, with pgb protein (phytoglobin, synonymous with non-symbiotic haemoglobin) increasing at lower atp. they based this crucial suggestion on their finding that mrna of phytoglobin (pgb) in barley aleurone tissue is induced in air by inhibitors of oxidative phosphorylation such as co, antimycin a, cyanide, and oligomycin, usually to the same degree as exposure to low o imposed by n flushing (nie and hill ). also, a combination of n and antimycin did not increase level of pgb transcripts above the level attained by each of these factors applied separately. using co, it was also shown that there was induction in air of adh and ldh transcripts, adh is one of the ‘anaerobic’ proteins listed by sachs et al. ( ). furthermore, there was induction of pgb mrna when atp formation by oxidative phosphorylation was inhibited by exposure to the uncoupler , dnp (nie and hill ). this uncoupler increases o uptake, which is in contrast with the metabolic inhibitors, further emphasising that tissue concentrations or uptake of o are not directly involved in inducing these transcripts. the caveat for the uncoupler is that the high o consumption, resulting from this uncoupler, may have led to development of anoxic cores (armstrong and beckett a), so in this case o concentrations in the tissue should be measured to ensure such anoxic cores had not developed. as early as beevers showed that ‘anaerobic’ metabolism, as evidenced by acetaldehyde and ethanol formation, became engaged during exposure to - dinitrophenol in fully aerated tissues to the same extent as in anoxia (beevers ). consistently, felle ( ) referred to effects of inhibitors on well-aerated tissues as ‘chemical anoxia’; and kato-noguchi ( ) concluded that o itself was not involved directly in accumulation of ethanol, which occurred both during anoxia and in well-aerated tissues in which the etc was inhibited. as well, features of ‘anaerobic metabolism’ in air were found for leaves of red pine and paper bark: treatments were exposure to so , freezing, water deficits and ozone (kimmerer and kozlowski ). the relevance of ethanolic fermentation in air was also emphasised in relation to disease resistance and stress (tadege et al. ). the similar response, irrespective of the cause of the energy crisis, is also shown by a typical decrease in phcyt occurring in cells not only rapidly after the start of anoxia, but also after addition of several inhibitors of oxidative phosphorylation during aeration (reviewed by felle ), as well as, albeit more slowly, during exposure to �c of cultured mung bean cells (yoshida ). so, a substantial case that interference with atp synthesis in the etc chain of mitochondria invokes ‘energy crisis metabolism’ has been made above; most of the tissues used in this work in well-aerated tissues had no reputation of high anoxia tolerance, so it would be advantageous to extend this work using extremely energy crisis-tolerant plant tissues (see ‘species and techniques’ in the second part of this review). apart from inhibitors, ‘anaerobic’ proteins are also induced in well aerated tissues by low temperature, low pi and wounding, which will now be discussed. low temperature: further support for induction of ‘anaerobic’ metabolism in aerobic conditions, comes from exposure of plants to temperatures between �c and somewhat above �c, particularly in tropical species. the v-h+-ppiase transcripts, proteins and enzyme activity at the tonoplast of functional plant biology h. greenway and w. armstrong rice shoots (cultivar ir ; – days after imbibition) were induced by chilling for – days at �c, though less pronounced than during anoxia (carystinos et al. ). in contrast, roots of day old maize had a high constitutive level of the v-h+-ppiase and showed little increase upon exposure to �c (carystinos et al. ). in another study with roots and shoots of a japonica rice variety and roots of maize, there were increases of -fold in adh transcripts, and of -fold in adh proteins after exposure for h to �c (christie et al. ). both christie et al. ( ) and carystinos et al. ( ) emphasised the responses of adh were similar to those during anaerobiosis, in both cases presumably related to energy deficits. they also emphasised there was only partial overlap between cold and anaerobiosis, with differences in the degree and time of change in adh (christie et al. ; carystinos et al. ) and more in general in pattern of proteins changing (christie et al. ). these data complement previous data on tropical and subtropical species, which repeatedly have been shown to produce ethanol and acetaldehyde upon chilling (lyons ). by far the most perceptive insight comes from work by lyons and raison ( ), who showed that chilling of isolated mitochondria of tropical species below � �c resulted in a steep break in the arrhenius plot, i.e. the q of o consumption (where q = (o uptake at t + )/(o uptake at t)) increased from . – . to between . and . (lyons and raison ). this . – -fold increase of the q with drop in temperature in the tropical species, compared with a q of . over the full range of to . �c for mitochondria of chilling tolerant species. these authors speculated from observed changes under phase contrast microscopy that the mitochondrial membrane altered its structure, so reducing the uptake of substrates into the mitochondria, hence slowing oxidative phosphorylation more than rates of glycolysis; the glycolytic enzymes being located in the cytosol would retain the usual q of . – . . the possible similar mechanism of acclimative response to o deficiency and to cold temperatures is also strengthened by the finding that cucumber seedlings had % survival after a h exposure to �c, provided they had been pre-treated at �c for h at kpa o . this survival compared with % for seedlings not pre-treated at kpa o (frenkel and erez ). we speculate that the o deficiency exposure at �c induced energy crisis proteins – enzymes that are also important in tolerance to cold temperature. this would be an alternative to the suggestion by frenkel and erez ( ) that the ethanol produced during o deficiency promotes fluidity of membranes. however lipophilic compounds will reduce atp concentration, so would lead to an energy crisis (see supplement , available as supplementary material to this paper). pi deficiency: another example of induction in aerated tissues of several enzymes involved in response to anoxia has been established during pi deficiency. during pi deficiency, there are increases in a suite of ppi-dependent enzymes including the v-h+-ppiase, sucrose synthase, pfk-ppi and ppdk (plaxton and podesta ). in brassica napus l. suspension cultures, pi deficient cultures exceeded pi sufficient cultures by -fold for the ratio v-h+-ppiase/v-h +-atpase measured as maximum catalytic activity and by . -fold for the v-h+-ppiase/v-h +- atpase protein (palma et al. ). importantly, pi starvation in brassica nigra l. suspension cells, also led to -fold decreases in atp and -fold decreases in adp concentrations (duff et al. ). thus, several of the metabolic changes during pi deficiency in air are similar to those occurring under anoxia (plaxton and tran ; atwell et al. ). the presently known difference between plant tissues during pi deficiency and anoxia is that nadh produced during catabolism is reconverted to nad+ by the alternative oxidase during pi deficiency (plaxton and tran ) and mainly via ethanol formation in anoxia (gibbs and greenway ) and possibly during anoxia also by the pgb-no cycle (igamberdiev and hill ; igamberdiev et al. ). the acclimative value of the ppi dependent enzymes is their use of ppi. this high energy compound is formed mostly during macromolecule synthesis, which includes atp conversion to ppi, with a free energy of hydrolysis for atp of kj mol– and that for ppi of kj mol – (davies et al. ; ph . ). in rapidly growing tissues ppi is hydrolysed to pi via a cytosolic ppiase (plaxton and podesta ). however, in the absence of the ppiase, the high energy bond in ppi can be used as an energy source, quite valuable during an energy crisis. in this review we comment further only on the acclimative- adaptive value of the v-h+-ppiase, which can be attributed to its function in maintaining integrity of the trans-tonoplast h+ gradient during energy shortage (plaxton and tran ; atwell et al. ). activity of the v-h+ ppiase would further be stimulated by the increase in soluble mg +, common under anoxia (igamberdiev and kleczkowski ). this acclimation would greatly increase energy efficiency by ‘saving’ atp (plaxton and tran ). additionally, the v-h+-ppiase may result in preferential energy flow to the tonoplast, which would have high priority in view of the crucial value of maintenance of tonoplast energisation to cell survival (carystinos et al. ). this hypothesis is quite relevant to cells in an energy crisis since defective cellular compartmentation of solutes would be fatal (felle ; atwell et al. ; also see ‘reduction in trans- membrane transport’ later in this review). in this context it is relevant that in rice, the specific activity of a tonoplast fraction became, under anoxia, -fold higher for both the total catalytic activity and the total protein for the v-h+-ppiase than for the v-h+-atpase (carystinos et al. ). we note that h+-ppiases have been reported for plasma membrane fractions of cotyledons of ricinus communis l. (long et al. ) and pisum sativum l. (robinson et al. ). there are some further examples in the review by maeshima ( ). so, there may also be some preferential energy flow to the plasma membrane. this suggestion has the caveat that the fractionation of the microsomal extract runs the risk of contamination of the plasma membrane (pm) fraction with enzymes of the tonoplast and other organelles (long et al. ; robinson et al. ). low levels of markers for other membrane fractions in the pm fraction are reassuring for a reasonable purity (long et al. ; robinson et al. ). even so, long et al. ( ) remained cautious, so did not reach a water tight conclusion. nevertheless, the results of the experiments with cotyledons are very promising. in view of the crucial importance of trans-membrane transport during an energy crisis it will be informative to have experiments on possible h+-ppiases in the plasma membrane of tissues very energy-crises in well-aerated and anoxic tissue functional plant biology tolerant to an energy crisis. if confirmed, these findings would reinforce the notion that part of the scarce energy is directed to trans-membrane transport, while atp requiring reactions would remain reduced. inter alia, these experiments would also provide a much needed test for the occurrence of pm-h+- ppiases, at least in some tissues or conditions. wounding: there is little information available for the link between wounding and energy deficits. cutting primary seminal roots of maize into – cm segments resulted in transient, h lasting, decreases of – % in atp and % in tissue k+ (gronewald and hanson ). as well, the pm membrane potential was depolarised from – mv to – mv (gronewald et al. ). a further link between wounding and an energy deficit is indicated by . – -fold increases in adh activity after crushing leaves of lettuce and maize with forceps (kato-noguchi ). similarly, – min mild agitation of cotton roots increased adh activity -fold, which was as much as during anoxia, and these increases were attributed to mitochondrial damage (dennis et al. ). the notion that oxidative phosphorylation was impeded after wounding is supported by decreases in cn sensitive respiration, concurrently with increases in cn resistant respiration (gronewald et al. ). the difference in degree of response between experiments can be expected since various wounding treatments may well differ in degree of injury. these results with wounding need confirmation since in some of the present experiments the tissues may have suffered a degree of o deficiency, due to destruction of porous structure. whether this confounding occurred can be tested by o microelectrode profiling measurements across the tissues (gibbs et al. ). further, the sugar status of the tissues is usually unknown and could suffer from the excision from the source. is ethylene involved in development of energy crisis metabolism in well-aerated tissues? possible relevance of ethylene to an energy crisis is strongly indicated by experiments in which rumex palustris sm. plants were exposed to ethylene at ml l– in air for h (van veen et al. ; further considered in w. armstrong, t. d. colmer, p. m. beckett and h. greenway (unpubl. data). the data by van veen may have relevance for many adverse conditions: ethylene emanates from tissues during a range of adverse conditions, which include, wounding, high salinity and drought (morgan and drew ), all which may lead to an energy crisis. new set point of phcyt during an ‘energy crisis’ phcyt: felle ( ) hypothesised that energy deficits lead to a new quasi steady state with a lower set point of phcyt . – . than in cells of well-aerated tissues. we review here detailed data obtained under anoxia of hypoxically pre-treated, – mm tips of intact maize roots. during anoxia these tips stabilised for at least h at phcyt . – . compared with . in the aerated tips and this phcyt did not respond to large decreases in energy production caused by exposure to mm fluoride and mm mannose (xia et al. ; phext . ); in other words, there must have been ‘surplus’ energy available in the roots without fluoride or mannose, yet that energy was not used to restore phcyt to the set point in air. of particular importance is the observation that anoxic maize root tips at phext . with a phcyt . , responded to fusicoccin – the stimulator of the pm-h+-atpase – by an increase in the rate of the pm-h+-atpase of as much as mmol g– fw h– (xia and roberts ). yet, this potential for h+ pumping across the pm had not been engaged, before fusicoccin was applied to restore the phcyt to the set point of . in air. in felle’s words, ‘it is pointless to restore the aerobic ph, since that would merely reinstate a high energy requiring regime’ (felle ). during an energy crisis the new set point of phcyt is mainly maintained by a biochemical rather than a biophysical phstat. the new phcyt may last for a few hours and then decline further or last for days (felle ). the transient pattern is found for wheat shoots (menegus et al. ) and also for tips of hypoxically pre-treated mm maize roots at phext . (xia and roberts ) and mm root tips of triticum aestivum l. (kulichikhin et al. ). in the maize root tips, there was a plateau of phcyt near . between and . h after start of anoxia; subsequently phcyt dropped again precipitously to . , whereas tips failed to resume elongation during h of re-aeration (xia and roberts ). so, the changed metabolism in these cells only conferred transient survival. this precipitous decline of phcyt has been used as support for the notion that death would be caused by acidosis of the cytoplasm (greenway and gibbs ). more likely the decline is a consequence of a deterioration of membrane integrity due to failure to renew proteins and liquid constituents of the membranes (felle ). in this scenario one would expect a sudden collapse, as was the case in anoxic slices of storage root of red beet: upon return to air all cells retaining their anthocyanins, which are in the vacuole, restored their plasma membrane potential within a few minutes; furthermore, only those that had lost their anthocyanins remained at a donnan free space potential (zhang et al. ). in contrast, phcyt dropped by only . – . units in two extremely anoxia tolerant tissues, potamogeton stems and rice coleoptiles and the phcyt were maintained for days (dixon et al. ; kulichikhin et al. ; table ). the proposed new set point of phcyt (felle ) may thus be relevant to long-term exposure to anoxia-energy crisis. the question remaining is whether in anoxic rice coleoptiles and potamogeton stems the rather small decreases in phcyt of . – . units can trigger the profound changes in metabolism. reassuringly, similar rather small changes in phcyt triggered profound diurnal changes in crassulacean acid metabolism (hafke et al. ; table ). one exception to the general pattern of a decrease in phcyt during reduced energy production is that phcyt was . in potamogeton stems grown for days since the start of sprouting of the turions in air and anoxia (dixon et al. ). overall, the discussed data on phcyt show that tolerance to anoxia not only varies between tissues, but within the same tissues also depends on environmental conditions. that phcyt may act as a messenger to modify metabolism is supported by an interesting case of regulation of nitrate reductase. no – reductase (nr) activity and protein can be functional plant biology h. greenway and w. armstrong upregulated both during anoxia and during cellular acidification using respiratory inhibitors, weak acids, or when transferring no – deficient tissues to solutions containing no – (kaiser et al. ). in all cases, the activation of nr would be via adecrease in phcyt, but there is no chance that the activation of nr could be due to a decreased atp concentration per se, since even in anoxic tissues these atp levels remain well in excess of the known km of the enzymes involved in regulation of nr (table for atp concentrations in anoxia tolerant tissues; and botrel and kaiser ; kaiser et al. ; for the km of the regulatory enzyme of nr). unfortunately, the phcyt at which nr is activated is not known, so it is uncertain whether the modest decrease in phcyt of the very anoxia tolerant species during anoxia is large enoughto activate nr. if so, this would showthat, at least in some cases, the anaerobic response consists simply of a decrease in phcyt, caused by an energy crisis, and then engaging a system which exists in most plant tissues to modulate a key enzyme like nr.itshouldbenotedsomeofthetechniquesofbrotelandkaiser may have not been optimal (see supplement , some relevant examples of defects in techniques). reductions in energy charge and atp concentrations the induction of energy deficient metabolism in well-aerated tissueshows that inthis environment,at least, the primarycause is likely to be a reduction in atp concentrations (see also next section). the changes in metabolism are large, with changes in enzyme composition (using anoxia, see sachs et al. ; chang et al. ) and a slowing down of trans-membrane transport (felle ). before discussing these changes (in ‘reduction in trans-membrane transport’), we will consider the changes in the adenine nucleotide pool. reductions in oxidative phosphorylation, e.g. by anoxia, rapidly lead to decreases in energy charge and atp concentrations (drew ). for example, transfer of rice embryos to anoxia resulted, within minutes, in a decline of the energy charge from . to . (mocquot et al. ). individual adenine nucleotides were not reported, but in view of the high initial level of the energy charge it is sure there must have been a large drop in atp (see equation for energy charge in list of definitions). subsequently, the energy charge restores to close to values found in tissues with high oxidative phosphorylation. thus, energy charge may participate during the early acclimation to an energy crisis, but is unlikely to have much influence during the long-term survival of at least days of anoxic rice coleoptiles (kulichikhin et al. ; greenway et al. ). instead, atp concentration may be important: in the extremely anoxia tolerant rice coleoptiles the assessed atp levels in anoxia remained % lower than in air at and days after exposure to anoxia (table ; see table . phcyt in air and anoxia in anoxia tolerant species diurnal fluctuation in phcyt during crassulacean acid metabolism are given for comparison species and location phcyt in air phcyt in anoxia detail on timing reference rice coleoptiles . . h anoxia then air kulichikhin et al. ( ) rice shoot . . air then – h anoxia menegus et al. ( ) potamogeton stemsa . . in air and then during h anoxia dixon et al. ( ) leaves of crassulacean acid metabolism plantb phcyt after h in light phcyt after h in light hafke et al. ( ) . . – . ain a second experiment with days anoxia since sprouting, both air and anoxically grown stems were at ~ . , see text for further details. bkalanchoe diagremontiana. the changes are associated with malate synthesis during the night and malate consumption during the day. these data are included since they demonstrate that only small changes in phcyt can have profound consequences for metabolism. table . effects of anoxia on adenine nucleotides in cytosol of two plant tissues km atpasewasmeasured withpatch-clampat tonoplast – mm (hedrich et al. , )of pmatpase – mm(sze ). for crude membrane fragments of vicia faba protoplast, km for atp was mm (shimazaki and konde ). note that the percentage volume of the cytosol can be approximated from soluble protein concentrations, as was done for maize roots (protein soluble in . m k phosphate; spickett et al. ), but such values are much less precise than the atp values in the patch clamp studies plant material exogenous glucose assessed adenosine triphosphate (mm) in cytosol assumed % volume cytosol reference air anoxia mm maize root tips – -day-old plants with large seed reserves at – h anoxia xia et al. ( ) mm tips of rice coleoptiles average value of . and mm glucose at and h huang et al. ( a); also see ishizawa et al. ( ) energy-crises in well-aerated and anoxic tissue functional plant biology also ishizawa et al. ). so, atp requiring reactions, including h+-atpases, may be slowed during an energy crisis and that possibility will be discussed in the next section. a % decrease in atp (per unit fresh weight) after the start of anoxia in stems of potamogeton and sagatira (ishizawa et al. ) is probably not representative for the cytoplasm since after transferring to anoxia there are likely to have been large increases in the fw : protein ratio, which might well explain most, if not all, of the drop in atp level on a fresh weight basis. the only firm indication of a favourable energy status of these tissues is a slightly higher energy charge in anoxia than in air, rather than the usual lower energy charge. are the decreases in atp level large enough to reduce activity of the h+-atpases? to further elucidate whether atp concentrations limit the activity of the h+-atpases, we need their km values for atp and the atp concentration in the cytoplasm. the km values of the plasma membrane and tonoplast h+-atpases are very similar (table ). the km of h +-atpases at the tonoplast were assessed during patch clamp studies of isolated vacuoles; one of the advantages of patch clamp is that the atp concentrations at the tonoplast membrane are precisely known. km values were and mm for sugar beet and barley respectively (hedrich et al. , ). the assessed atp concentrations in the cytosol of anoxic maize root and rice coleoptiles were at, or below, most of the km values for atp on the h +-atpases (table ). so, it is possible that during an energy crisis atp might restrict the rate of the h+-atpases, at least partially, accounting for a reduced trans-membrane transport. clearly more firm evidence is required, including the km of the plasma membrane h+-atpases of the species concerned. particularly, data on species with high tolerance to an energy crisis would be valuable to further test the hypothesis by felle ( ) that, in anoxic tissues, pm-h+-atpases do not become engaged to restore the phcyt to the set point in air. it would also be worth checking whether the km values for atp of the h+-atpases change when the tissues are exposed to an energy crisis. the decrease in energy available for solute transport can be coped with in two ways. reduction in solute transport (see ‘reduction in trans-membrane transport’) and possible modification of transport proteins to achieve an energy efficient form, such as increased coupling ratios, e.g. numbers of protons pumped per atp hydrolysed (see below ‘energy budget during an energy crisis’). reduction in trans-membrane transport one key feature of energy deficient metabolism is that h+-co- transport is drastically reduced in nearly all tissues, so that only a low rate of the pm-h+-atpase is required (reviewed by felle ; atwell et al. ). the best known cases, based on k+ fluxes, are for rice coleoptiles (colmer et al. ) and grapevine roots (mancuso and marras ). recently it was shown for arabidopsis that outward k+ rectifiers channels were downregulated within h of the start of anoxia (wang et al. ). when there is no growth, such as in excised rice coleoptiles (huang et al. a) and aged beet root slices (zhang and greenway ), the residual membrane transport during an energy deficit, can be driven in two ways: by provision of some energy for residual h+ pumping, or by previously accumulated energy coined a ‘battery’ (greenway and gibbs ; felle ; atwell et al. ). these alternatives can be distinguished when net k+ fluxes are known, because a k+ net influx would indicate some residual activity of the pm h+- atpase. in contrast, the ‘battery’ would involve k+ net effluxes (greenway and gibbs ; felle ). the h+, entering the cells during any co-transport, would be neutralised by organic anions rather than be excreted (greenway and gibbs ; felle ). an indication of energy provision associated with residual h+ pumping was found for excised rice coleoptiles. these anoxic rice coleoptiles showed small net k+ influxes over h anoxia (huang et al. a; greenway et al. ) while there was substantial glucose and sucrose uptake (zhang and greenway ). in contrast, the ‘battery’ was presumably engaged in anoxia tolerant aged tissue of red beet: there was a small net rate of k+ efflux over h anoxia, even in the most anoxia tolerant state achieved: being aged tissues, which were hypoxically pre-treated (hpt) and supplied withglucose(zhangetal. ).therateofk+effluxwasroughly similar to the rate of net glucose uptake (zhang and greenway ). confirmation is required by measuring k+ and glucose fluxes in the same experiment (see supplement , available as supplementary material to this paper). further evidence for the action of the ‘battery’ was obtained by transferring excised, anoxic, rice coleoptiles from ph . to ph . , which changed a small net k+ influx at ph . to a continuous net k + efflux, with concurrent decreases in malate and succinate, as is predicted by the ‘battery’ concept (greenway et al. ). in contrast, at ph . there were even some increases in malate and succinate (greenway et al. ). so, these data indicate, at least for anoxic rice coleoptiles, substantial flexibility: with either residual pm h+-atpase activity being engaged to sustain h+- co-transport, or engagement of the ‘battery’ under more adverse conditions (atwell et al. ). eventually this ‘battery’ would, of course, be exhausted, and the substantial k+ loss may have fatal consequences (greenway et al. ); as discussed by demidchik et al. ( ) in terms of programmed cell death (see supplement for cases where the battery is predicted or alternatively, some h+-solute co-transport). of course, when there is rapid growth during anoxia, as for cells of potamogeton stems (koizumi et al. ) quite large k+ influxes would be predicted, but as far as we know these have not yet been measured. energy budget during an energy crisis ion transport is particularly suited for studies on energy budgets, since changes in rate of transport can be relatively easily measured, while rates of solute uptake in air are high and consume as much as % of the energy required for cell maintenance (penning de vries ; de visser et al. ; greenway and gibbs ). the first energy budget in anoxic plant tissues was constructed using coleoptiles of -day-old rice seedlings, anoxic since functional plant biology h. greenway and w. armstrong germination (edwards et al. ) and this information was further discussed by atwell et al. ( ), among others in relation to reductions in ion fluxes. the substantial reduction in the energy requirements for these fluxes must have contributed to survival and growth of the coleoptile over at least days anoxia (greenway et al. ). further insight was gained by exposing, acclimated excised, anoxic coleoptiles to an additional stress of – mm nacl, which in air would greatly increase ion fluxes. this challenge could not be met during anoxia in mm nacl, when the coleoptiles died (kurniasih et al. ). however, the anoxic coleoptiles survived at mm nacl for at least h, allowing comparisons between ion fluxes and energy production and the construction of a preliminary model on energy efficient transport during an energy crisis. we postulated energy efficient transport would be achieved by high coupling ratios of both primary transport systems (moles h+ extruded/moles energy consumed), and secondary transport systems (moles solute transported)/moles h+ influx for symports, or antiports). in addition, membrane permeability to solutes like na+ would be greatly reduced, thus minimising the amount of energy required for na+ transport to the external solution or vacuole (kurniasih et al. ). in general, one would expect leakage of all solutes has to be minimised and less selective transporters have to be de-activated. response during carbohydrate starvation carbohydrate starved tissues-organs have reduced time of survival (see reviews by vartapetian et al. ; gibbs and greenway ). in the present review we discuss the effect of carbohydrate starvation on ion fluxes in excised, anoxic, rice coleoptiles (huang et al. a). the first distinct difference between coleoptiles, with and without exogenous glucose, was between and h after the start of anoxia, when coleoptiles without exogenous glucose showed net losses of k+, p and cl–, but there was still net uptake by the coleoptiles supplied with mm glucose. at this time, return to air still resulted in resumption of rapid net uptake even in the carbohydrate- starved tissues. however, in the coleoptiles without exogenous glucose, longer exposure led to substantial net efflux of ions and after return to air at h after the start of anoxia, the carbohydrate starved tissues had only half to one-third of the net k+ and cl– uptake of the coleoptiles supplied with glucose (huang et al. a). similarly, in carbohydrate starved slices of red beetroot, the only cells which had lost their semi- permeability (see previously ‘new set point of phcyt during an ‘energy crisis’) were detected in sugar-starved slices (zhang et al. ). these results are consistent with felle’s ( ) hypothesis that death during anoxia is caused by collapse of trans-membrane gradients. the collapse of the coleoptiles is associated with a prior long-term reduced ethanol formation, which in the coleoptiles without exogenous glucose was only one-third and one-ninth of that in mm glucose as early as between – and – h after start of anoxia. this drastic reduction in inferred rates of glycolysis, and hence atp formation, could thus be tolerated for another – h, reinforcing the notion that trans-membrane transport is preferentially allocated energy. we note that atp concentration only declined precipitously between and h anoxia, from ~ to mmol g– fw h– (huang et al. a). conclusions this section strongly supports the notion that ‘anaerobic metabolism’ can be induced by several adverse conditions, including o deficiency, but also by inhibition of oxidative phosphorylation in well-aerated tissues. this reinforces the suggestion to use terms like ‘energy-crisis’ metabolism instead of ‘anaerobic’ metabolism, so highlighting that the changes in metabolism are triggered by a decrease in atp level and by inference in atp formation, or one of its consequences, not by the level of o per se (nie and hill ). such a revised definition would clarify understanding and improve efficiency of future investigations. however, such a change in terminology has to be based on a watertight case, since there will inevitably be confusion, particularly when comparing future and past publications. so, more detailed comparisons between responses to energy crises in anoxia and in air are a prerequisite to any change in terminology. further elucidation of the induction of ‘energy-deficient’ metabolism in well-aerated tissues might use either one of the conditions shown to result in aspects of energy crisis metabolism in well-aerated tissues, such as wounding or cold temperatures, or a suitable inhibitor of oxidative phosphorylation, for example antimycin a, which inhibits electron flow (stoimenova et al. ). in contrast to several other metabolic inhibitors, antimycin a does not prevent nitrite-driven atp formation in anoxic mitochondria (stoimenova et al. ) this atp formation is very small relative to oxidative phosphorylation but comparable in magnitude to that achieved in glycolysis linked to ethanol formation (stoimenova et al. ). there are indications that cytoplasmic atp concentrations, rather than energy charge, contribute to the decrease in the rate of proton extrusion by the pm h+-atpase. felle ( ) has presented a reasonably satisfactory scenario of how an energy crisis limits trans-membrane transport (felle ) and we suggested, in addition, that the use of energy efficient transport systems contribute to a favourable energy balance. so, the energy balance, which decreases at first, is rapidly restored till energy consumption is reduced enough to match the decrease in energy production. the second part of this paper will address some possible reasons for the large changes in transcripts and enzymes during anoxia-energy crisis, as well as some aspects of gene regulation when tissues are exposed to an energy crisis. genetic aspects: reasons for the multitude of changes in transcripts and enzymes in molecular studies during severe hypoxia-anoxia this second part of the review has the following main themes: general networks, anaerobic proteins, key anaerobic proteins, ‘o sensitive’branchofn-endrulepathway,messengers,choice of species, and confounding energy crisis and injury. preamble in this section we attempt to integrate physiological and molecular studies. exposure to severe hypoxia-anoxia (energy energy-crises in well-aerated and anoxic tissue functional plant biology crisis) leads to a multitude of changes in transcripts and enzymes, even in anoxia tolerant tissues. we propose that most of these changes are related to common networks, which canparticipateinacclimationtoawiderangeofconditions,which change growth and metabolism. the terms anoxia and anaerobic are used in this section because all the data quoted were collected during hypoxia- anoxia. of course, when the data of an energy crisis for well- aerated tissues are confirmed, and enlarged, the better term would be ‘energy crisis’. these general networks would be complemented with changes in transcripts and enzymes specific for each particular condition, in the present case with anaerobic (energy crisis) transcripts and enzymes. only some of these specific anaerobic enzymes would make the difference between anoxia tolerant and anoxia intolerant species. these enzymes endowing anoxia tolerance are referred to as ‘key anaerobic proteins’, a similar suggestion was made by shingaki-wells et al. ( ). to detect differences between anoxia-tolerant and -intolerant tissues in the key anaerobic proteins, efficient investigation requires a judicious choice between tolerant and/or intolerant tissues, knockout lines, mutants and overexpression lines. there is also a requirement to avoid methodology proven to lead to early injury under anoxia. otherwise, many of the changes in transcripts are likely to be associated with injury and approaching death, i.e. have no meaning for anoxia tolerance. similar suggestions have been given for studies on plant drought resistance, to account for up and downregulation of hundreds, if not thousands, of transcripts (blum ). networks that become engaged in response to many stresses are complemented by ‘anaerobic’ proteins in this review we concentrate on hypoxia-anoxia responses in solution culture. these responses to anoxia-hypoxia in solution culture should be clearly distinguished from responses to flooding, including submergence of plants in soil. the latter, more complex, environments may be high in co and ethylene, and include many changes in soil composition. such complex environments were characterised by shabala et al. ( ) as ‘of a high complex multi-factor stress type’. even in solution culture using anoxia tolerant rice coleoptiles, the anoxia response involves changes in thousands of transcripts and genes (lasanthi-kudahettige et al. ; shingaki-wells et al. ). the rice coleoptiles can survive anoxia for at least days (greenway et al. ), so there is no chance that an appreciable percentage of the changes is associated with severe injury and/or approaching death. to account for the large number of changes during hypoxia- anoxia, we propose that most of these changes are associated with networks common to most plant tissues, such networks would become engaged in many situations when growth slows down and metabolism is drastically altered (fig. ). for each given stress the engagement of these common networks would be complemented by transcripts and proteins specific for any particular stress, in the present case by anaerobic proteins. these anaerobic proteins will be divided into two groups depending on in which species they occur: (i) anaerobic proteins which are induced during anoxia in most plant species, especially in the roots; and (ii) key anaerobic proteins, which are only optimally expressed in anoxia tolerant tissues, such as the very anoxia energy crisis energy crisis, high nacl, drought, reduced growth cacyt increase common networks, les, n-end rule pathway, alternative oxidase decrease (?)atp, atp’adp; aec phcyt decrease key energy crisis proteins; highly expressed only in energy crisis tolerant species energy crisis proteins both anoxia tolerant and intolerant fig. . hypotheses on messengers that lead to induction of proteins during an energy crisis and other changes in metabolism. in particular, there is not much direct evidence that the adenylate pool directly leads to changes in metabolism. other secondary and cellular messengers cannot be excluded. functional plant biology h. greenway and w. armstrong tolerant rice coleoptiles, so accounting for the difference in tolerance between genotypes and tissues. networks common to many stresses one good candidate for this common network is the low energy syndrome (les) present in nearly all plants, including arabidopsis (tomé et al. ), or a similar network. les involves thousands of changes in transcripts, translation factors and proteins and is involved in acclimation to nutrient limitation, high salt, hypoxia, low and high temperature (tomé et al. ). it should be noted we think the term ‘low energy syndrome’ is unfortunate, since several of the adverse conditions, mentioned by tomé et al. ( ), do not necessarily involve a low energy status. the les network among others acts via metabolic reprogramming, repression of biosynthesis, energy preservation and protein breakdown. the alternative pathway (aox) has been coined a ‘survival protein’ (van aken et al. ) and presumably belongs to or supplements the les network. the km of the aox for o is quite high, but it may function in the well-aerated tissues, which are the main theme of the first part of this review. one main function of aox is the oxidation of reduced nucleotides. however, in -day-old anoxic rice embryos there was a decrease in aox in rice (narsai et al. ), consistent with our suggestion that aox might not be required in tissues highly tolerant to an energy crisis (w. armstrong, t. d. colmer, p. m. beckett and h. greenway, unpubl. data). we suggest, that the n-end rule pathway (graciet and wellmer ; see shortly) is part of, or is dovetailing, the les network. the exception is, of course, the ‘o sensitive’ branch of the n-end rule pathway, which will be discussed in the anaerobic protein section (‘the ‘o sensitive’ branchof the n- end rule pathway’ section). the n-end rule pathway has been reviewed by graciet and wellmer ( ), the pathway determines the type of proteins to be degraded during a large range of cellular and developmental stages. of course, deletion of one of the principal components of these general networks would decrease acclimation to many stresses, including anoxia. for a possible example of such a failure of common networks see below ‘hypotheses on messengers and their targets’. anaerobic proteins induced in most genotypes some of the anaerobic proteins are induced in both anoxia intolerant arabidopsis seedlings and anoxia tolerant rice coleoptiles; one of the best known examples is adh (see ismond et al. for arabidopsis; gibbs et al. for rice). consistently, many intolerant tissues have rates of ethanol formation as high as tolerant tissues (drew ; gibbs and greenway ). similarly, several molecular responses to low oxygen, such as induction of glycolysis and fermentation are conserved (shingaki-wells et al. ). further, in arabidopsis there was a . -fold overexpression of adh which did not improve anoxia tolerance of roots and shoots (ismond et al. ). consistently, it has been concluded that several molecular responses to low o , for example overexpression of adh by – -fold in cotton roots and by -fold in -day-old rice did not improve anoxia tolerance, though in this case ethanol formation was stimulated in the overexpressed lines, particularly in cotton (ellis et al. ; rahman et al. respectively). importantly, on a protein basis the adh levels in arabidopsis (ismond et al. ) were similar to those found in root axes of maize (andrews et al. ). the very high maximum catalytic activity of adh reached under anoxia raises the question ‘to what extent this high activity is required to achieve anoxia tolerance’? the adh- mutant of rice, with % of the maximum catalytic activity of adh and half the rate of ethanol synthesis of the wild type, suffered fatal consequences when germinated in stagnant solution (takahashi et al. ). in comparison, in maize root tips tolerance was only compromised when adh was reduced to % of the wild type (roberts et al. ). to what extent other putative ‘anaerobic’ enzymes can be reduced in expression without a fatal result requires further investigation. regarding sucrose synthase, a double mutant lacking this enzyme dies early when exposed to anoxia (ricard et al. ). similarly, participation of sucrose synthase in anaerobic catabolism of arabidopsis was proposed by bieniawska et al. ( ). yet, other work with arabidopsis shows mutants without substantial sucrose synthase, and wild types, had similar low anoxia tolerance, with all plants being dead after h anoxia (santaniello et al. ). it is relevant that maize roots, though only moderately tolerant to anoxia, are more tolerant than arabidopsis. so the different conclusions by ricard et al. ( ) and santaniello et al. ( ) can be interpreted by assuming that deletion of sucrose synthase only matters when the tissues have at least a reasonable degree of tolerance. we also include in this group of anaerobic proteins common to most species: the subgroup vii of ethylene responsive transcription factor (erf vii) of the ‘o sensitive’ branch of the n-end rule pathway (gibbs et al. , ; licausi et al. ). these proteins occur in both mono and dicotyledons (nakano et al. ). so, though it is likely they occur in other plant species, we do not know whether either the erf vii family and/or the ‘o sensitive’ branch are similar or superior in anoxia tolerant tissues than in arabidopsis (see ‘o sensitive’ branch of the n-end rule pathway’ section and supplement ). the key anaerobic proteins which endow anoxia tolerance we define the key anaerobic proteins as those which make the difference between anoxia intolerant and tolerant species tissues. these key ‘anaerobic ‘proteins’ would be expressed only in optimum amounts in tissues highly tolerant to an energy crisis, such as germinating rice seedlings. one crucial point that we make in this section is that there is now evidence that overexpressing of only one of these key anaerobic proteins, the v-h+ppiase, results in substantial improvement in performance during anaerobiosis and during cold exposure, when oxidative phosphorylation is also likely to be inhibited (see the first part of this review). though no proof, these observations augur well for the view that only a relative small number of proteins make the difference between anoxia tolerant and intolerant species. energy-crises in well-aerated and anoxic tissue functional plant biology importantly, the difference between anaerobic proteins and key anaerobic proteins would be in degree rather than in kind. for example, proteins such as pdc and pgb also increase during anoxia exposure in intolerant tissues (for recent reference for arabidopsis see paul et al. ). yet, tolerance can be still further enhanced by overexpressing the particular protein. present evidence indicates pdc, pgb, and the v-h+ppiase are such key anaerobic proteins. in contrast to adh, – -fold increases in expression of pdc, the entry port of pyruvate to ethanolic fermentation, substantially increased anoxia tolerance of arabidopsis (ismond et al. ). similarly, transgenic rice with a range of pdc expressions showed an excellent correlation between maximum catalytic activity of pdc and ethanol formation of the tillers (measured after h anoxia), as well as with % survival after days submergence (quimioetal. ).earlierworkontherateofethanolformation and maximum catalytic activity of pdc also led to the suggestion that anoxia intolerant wheat roots were low in pdc activity (waters et al. ). yet, there are contrary observations; in rice leaves overexpressing pdc resulted in decreased survival, possibly due to acetaldehyde toxicity (rahman et al. ). such negative results indicate that experiments involving modulation of pdc should allow for the possibility that the pdc/adh needs to be maintained within a certain range. pgb levels have as far as we know, not been measured in germinating rice. however the pgb-no cycle in anoxic rice mitochondria produced twice as much atp per unit protein as this cycle did in barley mitochondria (stoimenova et al. ). overexpressing the level of pgb in arabidopsis thaliana (l.) heynh. led to substantial increases in anoxia tolerance, but only for anoxically shocked plants (hunt et al. ). as an example, after h of anoxia both shoot and root tip survival were % for seedlings which were pre-treated at % o for h in both wild type and pgb+, but for anoxically shocked seedlings, shoot survivals were and % and root tip survivals were and % for wild type and pgb+ plants respectively (hunt et al. ). in moderately anoxia-tolerant maize roots, transgenic lines with increased levels of pgb increased atp levels . -fold, whereas deletion of the pgb protein decreased atp to % of the level in the wild type (sowa et al. ). another key anaerobic protein would be the v-h+ppiase (maeshima ; shimaoka et al. ), which does occur in arabidopsis. however, even a modest overexpression of a gene encoding the v-h+-ppiase (avp ) in arabidopsis significantly enhanced survival of shoots and roots after periods of anoxia of up to h (demmer ). similarly, the recovery of leaf growth after transfer to air (and to a lesser extent, root extension) was up to six times faster in avp overexpressers (demmer ). further, during exposure of rice seedlings for days to �c there was higher tolerance for two lines overexpressing the ovp v-h+-ppiase (zhang et al. ); this exposure to �c is likely to lead to an energy crisis (see the first part of this review). the two transgenic lines had and % more v-h+-ppiase and % survival compared with % of the wild type (zhang et al. ). similarly, overexpressing of the v-h+-ppiase resulted in improved tolerance to drought and high salinity (shabala et al. ). these data confirm that during an energy crisis overexpression of a single enzyme may lead to substantial improvement in tolerance. so, the v-h+-ppiase is likely to be one of the key anaerobic proteins, which, when fully expressed, contributes to the difference between tissues tolerant and intolerant to an energy crisis. overall, the data obtained so far with the v-h+- ppiase show that despite the multitude of changes in transcripts and enzymes a single enzyme can substantially enhance tolerance to an energy crisis. the ‘o sensitive’ branch of the n-end rule pathway recent works have made substantial progress with the elucidation of mechanisms of the molecular basis for formation of ‘anaerobic proteins (gibbs et al. ; licausi et al. ; kosmacz et al. ; paul et al. ). these mechanisms involve the group of erfvii transcription factors, including rap . and an ‘o dependent’ branch of the n-end rule proteolytic pathway, which is inactivated by hypoxia, thus inhibiting the breakdown of rap . (gibbs et al. ; licausi et al. ; kosmacz et al. ; paul et al. ). this inactivation presumably leads to an increase in rap . ; as well there might be de novo synthesis during hypoxia (paul et al. ). the large reduction in the rate of degradation of rap . and its transfer to the nucleus leads to formation, ormaintenance,ofasuite of‘anaerobic’ proteins(paul et al. ). these findings provide new insight into the mechanisms of anoxia tolerance of plant tissues. our contribution is confined to the questioning whether the pathway is regulated by o , or by an energy crisis. the authors refer to the branch as ‘o sensitive’ and as an ‘o sensor’ (gibbs et al. ; kosmacz et al. ; paul et al. ; fig. a). earlier, gibbs et al. , gave as an alternative to o sensing, that the ‘o sensing’ branch of the n-end rule pathway might be regulated by a consequence of decrease in energy formation, such as decrease in phcyt, or formation of reactive o species (gibbs et al. ; fig. a). as stated in the ‘networks’ sections above, we suggest that at least part of the induction of anaerobic metabolism is related directly to decreases in atp concentrations. this alternative suggestion would be consistent with our notion that the branch may be an ‘energy crisis’-sensitive rather than an o -sensitive branch of the n-end rule pathway (see fig. for the two alternatives). we suggest this terminology, since several ‘anaerobic’ enzymes also reach high levels in well-aerated tissues (see ‘energy-crisis metabolism in well-aerated tissues’). however, as stated in the conclusions of the first part, more work is needed to establish to what extent the detail of responses to energy crisis in well-aerated tissues is similar to that in hypoxic tissues. can the o sensitive n-end rule pathway be inactivated in air ? the question in the above heading is relevant to our theme, because the answer is a good test for the viability of our notion that the response to o deprivation is merely one example of the more general response to an energy crisis, even in well-aerated tissues. the cysteine-argine n-end rule pathway is regulated in aerated arabidopsis and hordeum vulgare. inactivation occurs in response to multiple stresses including drought and functional plant biology h. greenway and w. armstrong exposure to mm nacl (vicente et al. ). as stated by gibbs et al. ( ) the inactivation of the ‘o sensitive’ branch of the n-end rule pathway in air shows that in these cases o is not the regulator of the inactivation-activation of the o sensitive’ branch of the n-end rule pathway. gibbs et al. ( ) suggested down regulation in air may be achieved either by low no, or by some other types of regulation, such as shielding of the n terminus of the erf’s concerned. the principal message for our theme is that the regulation of the ‘o sensitive’ branch of the n-end rule pathway is very flexible. whether this flexibility extends to our present theme, i.e. whether down regulation of the o sensitive’ branch of the n-end rule pathway occurs in well-aerated tissues during an energy crisis, could be tested by some of the treatments, which result in an energy crisis in air (see also ‘energy-crisis metabolism in well- aerated tissues’). the question of whether low no may inactivate the pathway degrading erf vii’s in our case is worth considering briefly. the no possibility tends to be unlikely in our case, since as will be argued shortly, no production tends to increase in well- aerated tissues with inhibited phosphorylation (see ‘energy- crisis metabolism in well-aerated tissues’); hence based on work by vicente et al. ( ), the branch would remain active, i.e. there would be no accumulation of ‘anaerobic proteins’. first, no is expected to increase when the etc is inhibited (cvetskovska and vanlerberghe ), whereas in optimum conditions no production is close to zero (gupta and igamberdiev ). second, vicente et al. ( ) suggested a major role for nitrate reductase (nr), during the inactivation of cys-arg/n branch of the n-end rule pathway. nr is a major source of no, and nr activity is much reduced in the case of drought, allowing inactivation of the n-end rule pathway. however, as described in the ‘new set point of phcyt during an ‘energy crisis’ section, metabolic inhibitors applied to well- aerated tissues increase nitrate reductase activity. so the present indications are that no would not play a role in any regulation of the ‘o sensitive’ pathway of the n-end rule pathway in well- aerated tissues. therefore, either fig. b is not realistic, or there is another type of regulation than o and no levels. one possibility may be deamination as found for the n-end rule pathway in yeasts (graciet and wellmer ). in conclusion, some of the treatments which result in ‘anaerobic’ metabolism in air (see ‘energy-crisis metabolism in well-aerated’) would be useful to test whether case (b) in fig. is a viable proposition and the mechanism by which it is achieved. of course, even a positive result cannot rule out that the inactivation of the ‘o dependent’ branch of the n-end rule pathway is triggered by two different mechanisms. enzymes that may not be critical for surviving an energy crisis, but which may optimise acclimation, over short or long-terms genes that are responsive to o deficits in micro-arrays cannot be expected to contribute equally to the physiology of survival and growth in tissues such as rice coleoptiles; that is changes in expression in a substantial array of genes may be needed to optimise anoxia tolerance, but only a few may endow a large measure of tolerance. for example, there are many changes during anoxia in intermediates and products linked to the tca cycle (shingaki-wells et al. ). in our view, several of these changes might occur when the tca cycle slows for whatever reason. others might have a useful role during anoxia, i.e. accumulation of succinate might enlarge the capacity of the ‘battery’ (see ‘reduction in trans-membrane transport’ and greenway et al. ). the possible reactions leading to succinate have been most recently reviewed by shingaki-wells et al. ( ). whether any of these changes are critical to long- term survival needs to be investigated. a relevant case may be alanine which accumulates during anoxia (shingaki-wells et al. ) to as high as mm in excised rice coleoptiles (greenway et al. ). however, the difficulty is that alanine- amino transferase in arabidopsis was involved in the decrease, not in the net synthesis of alanine, presumably during re-aeration (miyashita et al. ). a more straightforward case may be gaba, a metabolite considered to play a role during an energy crisis and which is formed by glutamate decarboxylase (shingaki-wells et al. ). one of the effects of the increase in gaba may be reduced k+ efflux, which was found for barley roots at mm nacl (cuin and shabala ). several other amino acids had a similar mitigating effect, but gaba is attractive to explore for anoxia since in -day-old rice seedlings gaba increased after h of anoxia from ~ . to . mmol g– fw in the shoots and . to . mmol g– fw in the roots (aurisano et al. ). in view of the mitigation of k+ loss it would be of interest to investigate whether gaba also plays a role during an energy crisis in highly tolerant rice coleoptiles, which during anoxia showed some k+ net uptake at ph . , but substantial k+ losses during exposure to ph . inhibition of oxidative phosphorylation decrease in phcyt, and/or membrane depolarisation energy crisis increases in erf group of transcription factors including rap . which mediates the formation of the proteins specific to an energy crisis inhibition of ‘energy crisis’-sensitive branch of the n-end rule pathway low o increase in erfvii group transcription factors, including rap . , which mediates the formation of the proteins specific to anoxia (paul et al. ). inhibition of the o sensitive branch of the n- end rule pathway (a) (b) fig. . the two mechanisms of how the ‘o sensitive’ (‘energy crisis’) branch of the n-end rule proteins could be regulated. (a) responses to low oxygen based on gibbs et al. ( ), kosmacz et al. ( ) and paul et al. ( ). (b) suggested responses in well-aerated tissue where anaerobic metabolism detected (see ‘induction of ‘anaerobic metabolism’ in well- aerated tissues’ section). energy-crises in well-aerated and anoxic tissue functional plant biology (greenway et al. ) (see also ‘energy budget during an energy crisis’). transport proteins in contrast to the proteins participating in intermediary metabolism, transport proteins are seldom increased in amounts or composition as shown in an excellent review by shabala et al. ( ). these authors found no substantial evidence for changes in most of the ‘transport proteins’. the exception being the convincing changes in the v-h+ppiase in germinating rice seedlings (carystinos et al. ). the same paper showed a -fold increase in the maximum catalytic activity of the v-h+atpase over days anoxia; even so the protein level and maximum catalytic activity of the v-h+atpase remained -fold lower than that of the v- h+ppiase (q. liu and b. j. atwell, unpubl. data; carystinos etal. ).presumably,mostoftheothertransportproteinswere acclimated via regulation of existing channels and carriers. for example rapid changes in the pm-h+-atpase are attributed to changes in membrane potential, there is no evidence for changes in pm-h+-atpase transcripts and proteins (shabala et al. ). such very rapid changes can be elicited over a few seconds to minutes, as is observed for the pm- h+-atpase (shabala et al. ). clearly, whether this general view holds, or whether there remain unknown changes in transport proteins, still needs to be further tested. at present, we suggest that the many fold changes in enzymes of intermediary metabolism can be attributed to the large changes in metabolism, which may occur in all conditions when environmental conditions change. regarding transport proteins, plant tissues are always challenged by large changes in external ion concentration and other events requiring changes in transport. this general occurrence may therefore account for the predominance of regulation of existing proteins rather than induction of special transporters to cope with an energy crisis. summing up, we suggest that most plant species can acclimate to an energy crisis which is transient and so can survive an energy crisis for hours and sometimes as long as a day. a few very anoxia tolerant species tissues are distinguished by strong expression of some key ‘anaerobic’ proteins. the above information gives clues as to which plant’s tissues and mutants are most likely to be useful to elucidate the characteristics that lead to the vast difference between tissues in tolerance to an energy crisis. aquaporins aquaporins close under anoxia (maurel et al. ) and at reduced ph (frick et al. ). however, we could not find a rationale for this closure in terms of energy saving, an issue that deserves further investigation. hypotheses on messengers and their targets after discussing the various components of anaerobic metabolism, we will now suggest which messengers may mediate the change from aerobic (energy plenty) to anaerobic (energy crisis) metabolism (fig. ). ca +cyt: increases in ca + cyt at the onset of anoxia are well established and change activities of many enzymes (for an excellent review see sachs et al. ). however, such increases in ca +cyt occur during several conditions apart from an energy crisis (hepler and wayne ) so ca is not specific for anaerobic metabolism. instead, we suggest the increase in ca +cyt is a messenger to engage networks common to plant tissues under several adverse conditions (fig. ). ca + as a messenger was also involved in activation of starch hydrolysis in -day-old rice (ho et al. ). both changes in ca + level and activation of amylases are involved in rice under multiple abiotic stresses (ho et al. ). so, we suggest that the response is not specific to anoxia but part of a common network. this suggestion in no way implies that the mechanisms of such common networks are not interesting, but we have concentrated on specific anaerobic proteins and their distinction from proteins of common networks (fig. ). though not specific for anaerobiosis, the common networks would remain important for survival during anoxia. support for this notion was found when increase in ca +cyt was prevented using ruthenium red: during flooding of maize, survival of the maize root tips was as short as h compared with h for tips withincreasedca +cyt(sachsetal. ).thisassertionassumes,as indicated in fig. , that high ca + cyt is a messenger that triggers engagement of common networks, rather than of only specific anaerobic proteins. phcyt: phcyt is often considered as a messenger in several conditions resulting, among others, in activation of genes, protein kinases and changes in membrane transport (felle ). felle in this case prefers the term ‘cellular messenger’. phcyt was ingeniously manipulated by phext changes and applications of butyric acid (a weak acid) and methyl amine (a weak base) (fox et al. ). such treatments showed no artefacts during h exposure to phext between and , giving sufficient time to evaluate the possible role of phcyt as a messenger. among others, it was demonstrated that a change in phcyt in air did not trigger ethanol formation, i.e. as stated by fox et al. ( ), the switch to ethanol formation requires another factor in addition to a decrease in phcyt. changes in adenylate nucleotide pool: we suggest decreases in atp, atp/adp, and/or energy charge might also directly change metabolism (fig. ). a case for atp concentrations affecting the rate of atp-h+ases was made in the in the first part of this review, viz. ‘are the decreases in atp level large enough to reduce activity of the h+-atpases?’. inhibition of starch hydrolysis rice was the only cereal able to develop and activate starch hydrolysis during anoxia (perata et al. ). even several rice varieties are ‘sensitive’ to flooding in the germination stage (ho et al. ), sensitivity due to insufficient starch hydrolysis and failure to emerge in flooded fields. the study by ho et al. ( ) also highlights the importance of making comparisons between treatments at the same stage of development (as advocated by blum ). thus the ability to activate starch hydrolysis during anoxia is only well developed in some rice varieties. detail on these varietal differences was obtained in a study with varieties exhibiting different abilities to develop a coleoptile during anoxia (huang et al. ). in an indica variety (ir ) that developed very slowly during anoxia, glucose in the endosperm was lower in anoxic intolerant than tolerant varieties. for example, at days after the start of anoxia functional plant biology h. greenway and w. armstrong at germination, the endosperm of the most tolerant variety was times higher in sugar than in the intolerant variety (huang et al. ; japonica and indica respectively). no other major process seemed to be defective in the intolerant cultivar; transport from endosperm to embryo was unimpaired as shown by the high ratios of sugar in the embryo/endosperm. further tests with excised coleoptile tips supplied with glucose showed no cultivar differences in the rate of ethanol fermentation and anoxia tolerance as measured by rapid resumption of rates of net k+ and p uptakes (huang et al. ). thus, in general, the main puzzle is why the common network of the sugar cascade often does not become engaged under anoxia and not fully activated in the intolerant rice cultivars. for the wheat, the delay in development due to the inability to activate the sugar cascade may be of advantage by delaying germination till more favourable conditions arise (perata et al. ). we cannot suggest any acclimative advantage for the intermediate response of ir . in conclusion, the response of imbibed seeds to anoxia is an interesting phenomenon which could only be briefly considered in this review and deserves further consideration. choice of species for investigation here we compare the merits of arabidopsis and rice coleoptiles, the most frequent objects of investigation. arabidopsis is a species that is very intolerant to anoxia, and has been successfully used to elucidate many aspects of response of tissues to an anoxia-energy crisis (see ‘networks’ sections above). as is well known, the advantage of arabidopsis is its small and sequenced genome and the ease to get mutants; its main drawback is that so far none of the known genotypes mutants has a really high tolerance to an anoxia- energy crisis. one attractive possibility is to do similar molecular studies with rice. rice is diploid, has a sequenced genome (goff et al. ) and has many useful mutants (hirochika et al. ). further, several genotypes have a very high tolerance to anoxia, so far established for the coleoptiles during germination; the high tolerance excludes the confounding of results relevant to an energy crisis with changes due to injury and approaching death (see ‘deficient experimental techniques’ below). the germination phase has also the advantage of the ease of imposing anoxia on a simple system: consisting only of seeds and coleoptiles. there is an extensive literature on the response to anoxia of these germinating rice seeds (recently reviewed by atwell et al. ). the suggestion to further employ rice seems to contradict the view expressed by shabala et al. ( ), that therehasprobablybeentoomuchemphasisonrice.however,that contradiction is only apparent when considering that these authors were concerned with the multifactor stress of flooding, whereas the present review is focussed on an energy crisis of tissues in solution culture. hence, our emphasis on germinating rice seedlings was deliberate as the most straight forward route to elucidate anoxia tolerance. to elaborate somewhat, we caution against failure to clearly distinguish the phenomenon of germinating rice under an energy crisis and the tolerance to complete submergence of whole rice plants, in the latter case anoxia tolerance has a subsidiary role to elongation (colmer et al. ). whether rice leaves and/or roots ever have a high tolerance to anoxia-energy crisis is still doubtful (roots reviewed by gibbs and greenway ). studies on rice mutants have been quite rewarding to elucidate responses of roots differing in suberin during flooding (shiono et al. ). regarding the use of rice mutants to study metabolism during an energy crisis, the only studies we know are with young seedlings, including mutants lacking adh- (see above: ‘anaerobic proteins induced in most genotypes’ ). summing up, if mutant lines for specific genes involved in an energy crisis could be found in rice, the great advantage wouldbe thattolerant andintolerant tissues from thesame species can be compared, rather than, for example, arabidopsis with rice coleoptiles. confounding responses to an energy-crisis-anoxia- tolerance with responses to injury the possible confounding of features of energy crisis tolerance with responses due to injury needs some further emphasis. felle ( ), considering data obtained with anoxia-intolerant species, comments on the difficulty of distinguishing the period when there is a new set point for phcyt and the subsequent period of fatal decline in phcyt. another example is for hypoxically pre- treated, . -day-old maize roots (carystinos et al. ): after a further days anoxia, both the v-h+atpase and the v-h+ppiase of the mm root tips declined by and % respectively (basis, protein of isolated microsomes). these authors suggested the likely cause for this decline in the maize root tissues was tissue damage. in contrast rice seedlings increased in both these translocases over days anoxia, i.e. the patterns indicated injury in maize and acclimation in rice respectively. there is no problem of confounding changes due to acclimation with changes due to injury when using anoxia tolerant species such as red beet storage root tissue and tolerant genotypes of rice coleoptiles. indeed these tissues need special adverse conditions, such as those leading to carbohydrate starvation; or high temperatures, to trigger a fatal decline. deficient experimental methodology it is important to establish that growth resumes after re-aeration of tissues that have been exposed to an anaerobiosis energy crisis, to demonstrate there has been no permanent injury (thomas et al. ). we would like to sharpen the criterion by thomas et al. ( ) by adding ‘with a time course over the first hours after return to air’, otherwise quite serious injury might have been repaired. unfortunately, even in recent papers there are either no recovery tests, or more frequently, the first data after transfer to aeration are obtained a few days after re- aeration, e.g. days after a prior h of anoxia (paul et al. ) and days after h hypoxia (gibbs et al. ). further, the survival criteria are often photographs and visual scores on chlorosis, e.g. taken at days after return from anoxia to air (gibbs et al. ). none of these tests excludes serious injury during exposure to anoxia, which may have been repaired during the long period of re-aeration. studies need time-courses of observations of sensitive indicators of cell performance starting during the first hours after re-aeration. suitable ones include plasma membrane potential, resumption of extension growth and of energy dependent uptake using cl– at an energy-crises in well-aerated and anoxic tissue functional plant biology external concentration requiring energy dependent transport (e.g. . – . mm cl–). only when such tests show that over the period of observation there was no serious injury does it become worthwhile to do metabolic and molecular studies on anoxia tolerance. for studies on anoxia tolerance several techniques leading to injury were listed by gibbs and greenway ( ) and a few further comments are provided in supplement . another serious deficiency in methodology is the failure to acclimate the tissues before transfer to anoxia; then, as demonstrated first by saglio et al. ( ) with mm tips of roots of intact maize plants, anoxic shock results in early death and/or injury. hypoxic pretreatment is now used by many workers, but unfortunately the pre-treatment with mm o (suitable for maize roots) has been applied to other species. this adoption may be unwarranted, since endogenous o concentrations depend on several factors (w. armstrong, t. d. colmer, p. m. beckett and h. greenway, unpubl. data). a simple o response curve of tissue respiration with a clark electrode and cuvette can establish a likely suitable o concentration for hypoxic pretreatment (see supplement ). a second confounding factor may be deficiency of carbohydrates by limiting substrates for glycolysis. this phenomenon has been known since the s (gibbs and greenway ; vartapetian et al. ). in this review we have mainly considered some experiments with rice seedlings, or coleoptiles (see earlier ‘energy budget during an energy crisis’). sucrose addition also increased anoxia tolerance of arabidopsis (paul et al. ). so, unless the aim is to study the consequences of the interaction between hypoxia and sugar starvation, the standard procedure should be to supply sugars. yet another pitfall is not to cater for different pattern of development during comparisons of genotypes. for example, during studies on drought resistance, samplings of different genotypes, or other treatments, are all taken on the same day, rather than taking tissues of the same level of plant water status. as another example, relative expression of cbl , clpk - and ramy d (the start of the sugar cascade) in coleoptiles was, unexpectedly, much larger in anoxic than aerated -day-old rice seedlings (ho et al. ). however, this difference is presumably due to early senescence of the aerated coleoptiles as indicated by a -fold decrease in atp concentration between the first and third day after the start of germination in air, whereas the atp decrease in anoxia was only . -fold (ishizawa et al. ), with both treatments having around the same atp concentration on day . so, the better comparison would have been between coleoptiles of aerated seedlings on day and anoxic seedlings at day . conclusions the data indicating that ‘anaerobic’ metabolism can occur in well-aerated tissues, when oxidative phosphorylation is inhibited have been discussed in the conclusions to the first part of this review. we have suggested these changes in metabolism are complemented by changes in ion transport such as more energy efficient coupling ratios and reductions in membrane permeabilities to solutes (see ‘reductions in energy charge and atp and reductions in trans-membrane transport’ in the first part of this review). the special case of o deficiency and anoxia remains worth detailed consideration, partly because this case has been intensively investigated and partly because of its relevance to flooding tolerance of plants. the frequently observed numerous changes in transcripts and enzyme levels during anoxia (see ‘networks’ sections) can partly be explained by injury and approaching death associated with use of anoxia intolerant species and/or faulty techniques. however, even in anoxia tolerant germinating rice seedlings investigated in experiments with satisfactory techniques, there are still multitudes of changes in levels of transcripts and proteins (huang et al. b; lasanthi-kudahettige et al. ; shingaki-wells et al. ). we propose that these are mainly related to the large change in metabolism changing from a condition providing plenty of energy to an acute energy crisis. many of these changes may be related to the les network common to a range of adverse conditions where metabolism is drastically altered. the n-end rule pathway (excluding the ‘o sensitive’ branch) would also be relevant to many conditions when metabolism changes. these general networks would need to be complemented by a much smaller array of enzymes associated specifically with an energy crisis, caused by inhibition of oxidative phosphorylation. of these key energy crisis proteins several (adh among others) occur in anoxia intolerant and tolerant tissues. another important aspect relates to the de novo synthesis of the energy crisis enzymes involving erf transcription factors and the ‘o sensitive’ branch of the n- end rule pathway. we suggest there may be another group of anaerobic proteins, which we call ‘key anoxic proteins’, which would occur in sufficient amounts only in tolerant tissues so that these proteins would contribute to the difference in tolerance between species tissues. presently it seems the energy crisis enzymes occurring in both tolerant and intolerant tissues are mainly those involved in glycolysis. the key energy crisis proteins expressed specifically in tolerant tissue include pgb, the v-h+ppiase and pdc. in contrast, changes in proteins of carriers and channels for ion transport have so far not been found, excluding the well-known case of the v-h+ppiase. instead, regulation of existing proteins of ion transporters seems to be the norm. in view of the crucial importance of maintaining trans-membrane gradients we suggest it would be of value to research possible differences in regulation of ion transport between anoxia tolerant and intolerant tissues. carbohydrate starvation leads to irreversible injury of rice coleoptiles, even so this injury occurred only as late as h after ethanolic fermentation had already been drastically curtailed. clearly at least all energy saving devices discussed are particularly relevant to cases where an energy crisis is due to carbohydrate starvation. finally, we suggest there are two main routes for gene manipulation to further the elucidation of mechanisms of tolerance to an energy crisis: ( ) comparisons between very tolerant and intolerant species, and ( ) manipulations within a particular species. for comparisons with tolerant tissues like germinating rice, one choice would be arabidopsis, with the vast information and its huge genetic variation. however, it may be more useful in the future to concentrate on rice, since its genome yields ample genetic variation and can be relatively easily manipulated. the great advantage would be that the anoxia intolerant and tolerant genotypes would be rather functional plant biology h. greenway and w. armstrong similar, except in respect to their difference in tolerance to an energy crisis. conflicts of interest the authors declare no conflicts of interest. acknowledgements the authors thank steve tyerman for many incisive criticisms, mainly on the transport sections, as well as encouragement for completing the review; 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- - dx.doi.org/ . /annurev.pp. . . dx.doi.org/ . /annurev.pp. . . dx.doi.org/ . /s - ( ) - dx.doi.org/ . /aob/mct dx.doi.org/ . /j. - . . .x dx.doi.org/ . /tpc. . dx.doi.org/ . /tpc. . dx.doi.org/ . /aob/mcf dx.doi.org/ . /aob/mcf dx.doi.org/ . /jxb/ . . dx.doi.org/ . /pp. . . dx.doi.org/ . /pp. . . dx.doi.org/ . /pp. . . dx.doi.org/ . /pp dx.doi.org/ . /jxb/ . . dx.doi.org/ . /j.plaphy. . . dx.doi.org/ . /j.plaphy. . . cqy volume cover and front matter the china quarterly april/june richard wich byung-joon ahn arif dirlik patricia griffin frederick teiwes perry link use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core the origins of the cultural revolution volume i: contradictions among the people - roderick macfarquhar in the course of the strange events of the cultural revolution it became clear that chairman mao himself was the progenitor of the movement. the three volumes of this study will seek to explain mao"s apparently inexplicable behaviour by showing how a combination of political, economic, social, and international developments, as well as cultural ones, led him to make his fateful decision. the author presents a history of the tumultuous decade that preceded it, drawing on the revealing documentary materials which appeared during its course and after, as well as on the even more copious material of the pre-cultural revolution period. ths is also the first study to make use of hitherto secret mao speeches which became available in the summer of . the present volume deals with the famous episode of the blooming of the ' hundred flowers '. £ - royal institute of international affairs oxford the china reader iv: people's china social experimentation, politics, entry onto the world scene, through edited by david milton, nancy milton, and franz schumann. the latest volume in the highly praised "china reader" series, this is a documentary history of china from the onset of the cultural revolution to the country's emergence as a major world power. among the political leaders, literary men, scholars, and journalists contributing to the volume are anna touise strong, joan robinson, mao tse-tung, touis kraar, james reston, joseph alsop, and edgar snow. $ hardcover; vintage paperback $ . a history of the chinese cultural revolution by jean daubier. translated by richard seaver, with a preface by han suyin. a french marxist who participated in the revolution presents an eye-witness account of the events, and examines their meaning for other marxist regimes. "the first book on the cultural revolution to take the ideology behind it seriously. . . [oaubier'sl own personal experience of the cultural revolution adds an extra dimension to the records." _ john gittings. a vintage original. $ . vintage books a division of random house use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core the china quarterly an international journal for the study of china april/may number £ . $ . obituaries the tenth party congress: the power structure and the succession question richard wich the cultural revolution and china's search for political order bynog-jooq aim national development and social revolution in early chinese marxist thought arif dirlik prison management in the kiangsi and yenan periods patricia griffin reports from china before and after the cultural revolution frederick c. teiwes li hsi-fan on modern chinese literature perry link note chinese maps: an exhibition at the british library howard nelson review article the uses and limits of elite studies: the chinese case frederick c. teiwes book reviews chine rouge, page blanche. by pierre illiez china's socialist revolution. by john and elsie collier. marianne bastid use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core contents—continued the politics of chinese communism: kiangsi under the soviets. by ilpyong j. kim documents of the chinese communist party, - . ed. hyobom pak. james p. harrison history and will. philosophical perspectives of mao tse-tung's thought. by frederick wakeman. wolfgang bauer economic organization in chinese society. ed. w. e. willmott. marianne bastid general stilwell in china, - ! the full story. by liang chin-tung. steven l levine women in china. ed. marilyn young. emily macfarauhar doing business with the people's republic of china. ed. business inter- national. norman webb god, ghosts, and ancestors: the folk religion of a taiwanese village. by david k. jordan. chung-min chen chinese communism - .' experience in civil government. by trygve lotveit. chi-hsi ha china and the world community. ed. ian wilson. harold c. hinton women and child care in china. by ruth sidel. susan rifkin an introduction to chinese civilization. ed. john meskill with j. mason gentzler. tilman spengler china: an index to european visual and aural materials. ed. k. l. pratt and d. w. s. gray. desmond painter the people's comic book. trans. endymion wilkinson. jonathan mirsky china's population struggle. by h. yuan tien. leo a. orleans philosophy and revolution, from hegel to sartre and from marx to mao. by raya dunayevskaya. phil biuingsley the role of 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foreign policy viability of the leninist synthesis caribbean exile invasions: a special regional type of conflict u.s.-south asian relations in the 's: a conference report review articles on important new books in the field of international relations orbis is published four times yearly, in february, may, august and november. individual copies: $ . . subscriptions: one year, $ . ; two years, $ . ; three years, $ . . address orders to: the foreign policy research institute market street, soite , philadelphia, pa. use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core energy crisis precedes global metabolic failure in a novel caenorhabditis elegans alzheimer disease model research collection journal article energy crisis precedes global metabolic failure in a novel caenorhabditis elegans alzheimer disease model author(s): fong, sheng; teo, emelyne; ng, li f.; chen, ce-belle; lakshmanan, lakshmi n.; tsoi, sau y.; moore, philip k.; inoue, takao; halliwell, barry; gruber, jan publication date: - - permanent link: https://doi.org/ . /ethz-b- originally published in: scientific reports , http://doi.org/ . /srep rights / license: creative commons attribution . international this page was generated automatically upon download from the eth zurich research collection. for more information please consult the terms of use. eth library https://doi.org/ . /ethz-b- http://doi.org/ . /srep http://creativecommons.org/licenses/by/ . / https://www.research-collection.ethz.ch https://www.research-collection.ethz.ch/terms-of-use scientific reports | : | doi: . /srep www.nature.com/scientificreports energy crisis precedes global metabolic failure in a novel caenorhabditis elegans alzheimer disease model sheng fong ,*, emelyne teo ,*, li fang ng , ce-belle chen , lakshmi narayanan lakshmanan , sau yee tsoi , philip keith moore , takao inoue , barry halliwell & jan gruber , alzheimer disease (ad) is a progressive neurological disorder characterized by the deposition of amyloid beta (aβ), predominantly the aβ – form, in the brain. mitochondrial dysfunction and impaired energy metabolism are important components of ad pathogenesis. however, the causal and temporal relationships between them and ad pathology remain unclear. using a novel c. elegans ad strain with constitutive neuronal aβ – expression that displays neuromuscular defects and age-dependent behavioural dysfunction reminiscent of ad, we have shown that mitochondrial bioenergetic deficit is an early event in ad pathogenesis, preceding dysfunction of mitochondrial electron transfer chain (etc) complexes and the onset of global metabolic failure. these results are consistent with an emerging view that ad may be a metabolic neurodegenerative disease, and also confirm that aβ-driven metabolic and mitochondrial effects can be reproduced in organisms separated by large evolutionary distances. alzheimer disease (ad) is a neurological disorder characterized by progressive memory impairment and cog- nitive deficits. the neuropathologic hallmarks of ad are deposition of plaque-forming amyloid beta, predomi- nantly as a -amino acid peptide (aβ – ) , and of tangle-forming tau protein aggregates . mitochondrial dysfunction and defective energy metabolism are features consistently found in human ad. reduced energy production, lower oxygen consumption, and decreased complex i and iv activities have all been observed in ad brains (reviewed by ref. ). similar metabolic alterations have been observed in model organisms, including transgenic mice (reviewed by ref. ) and nematodes overexpressing human aβ . however, exactly how and at what stage of the disease mitochondrial dysfunction occurs remain incompletely understood. the nematode worm caenorhabditis elegans has several unique advantages as a model organism for ageing and neurodegenerative diseases (reviewed by ref. ). due to its genetic tractability, stereotypical nervous system, rapid life cycle, short lifespan ( – weeks) and relatively low cost, c. elegans may be employed in ways that would be time, labour and cost prohibitive in mammalian models. a validated model of mitochondrial aβ toxicity in neurons in c. elegans would therefore be valuable as a screening platform for drug discovery to expedite develop- ment of future ad therapeutics. while numerous transgenic c. elegans strains have been generated to study ad (see supplementary table s ), none of the existing strains has constitutive pan-neuronal aβ – expression or displays an age-related onset of behavioural dysfunction, such as that observed in human ad. we have therefore developed a novel c. elegans strain with constitutive pan-neuronal aβ – expression and aimed to clarify the temporal relationships between energy metabolism, mitochondrial dysfunction and neurodegeneration in ad pathogenesis. to facilitate delinea- tion of the temporal sequence of these events and for screening and intervention testing, we aimed at generating a strain that would exhibit progressive neuronal dysfunction and middle-age-onset behavioural phenotypes. to this end, we first constitutively expressed full-length human aβ – peptide in all nematode neurons at different gene internal medicine residency programme, singhealth group, singapore. nus graduate school for integrative sciences and engineering, national university of singapore, singapore. science division, yale-nus college, singapore. department of biochemistry, national university of singapore, singapore. institute of chemical and bioengineering, eth zurich, switzerland. *these authors contributed equally to this work. correspondence and requests for materials should be addressed to j.g. (email: bchjg@nus.edu.sg) received: january accepted: september published: september open mailto:bchjg@nus.edu.sg www.nature.com/scientificreports/ scientific reports | : | doi: . /srep doses, and selected a line with late onset behavioural phenotypes. after characterizing the behavioural deficits in the aβ -expressing nematodes, we then investigated the temporal relationships between energy metabolism, mitochondrial dysfunction and neurodegeneration. results generation of constitutive pan-neuronal aβ – -expressing nematodes. due to unexpected post-translational n-terminal truncation of full length human aβ – , several of the current c. elegans ad strains have been shown to accumulate truncated aβ – , a form that does not significantly contribute to ad pathology in the human brain . to avoid this issue, we added additional nucleotides (gatgct) to the ′ dna end of the human aβ – minigene sequence. this sequence has been shown by mccoll et al. to be processed to generate full length aβ – in c. elegans (see supplementary fig. s a). in addition, we optimized the codons in the aβ – minigene for optimal aβ – expression level in nematodes (see supplementary fig. s b). following the creation of stabilized transgenic nematodes, we performed reverse transcription polymerase chain reaction (rt-pcr) and western blot to confirm the presence of human aβ – mrna and protein. using a commercialized taqman human aβ gene assay, we first confirmed via real-time pcr that human aβ – mrna is produced in our aβ -expressing nematodes but not in the controls (fig.  a). to verify that the aβ – mrna expressed was indeed the full length sequence, we performed another pcr reaction using primers flanking the full length aβ – sequence and showed that the fragment size obtained from the aβ -expressing nematodes cor- responds to that of the human aβ – minigene (fig.  b). dna sequencing of the fragment further confirmed it to be the codon optimized aβ – sequence (see supplementary fig. s c). immunoblot analysis showed that human aβ – protein was detected only in the insoluble (resolubilised in m urea), but not the soluble protein fraction of aβ -expressing nematodes, suggesting that aβ is found mainly in aggregated proteins in our transgenic nematodes. expression of aggregated aβ protein was only detectable in old nematodes (day ) but not when they were young (day ) or middle-aged (day ; fig.  c,d), which correlates to the age-related deterioration in behavioural and biochemical deficits of the aβ -expressing nematodes. it is important to note that this correlation does not imply any causation. in particular, urea soluble aβ aggregates themselves are not necessarily responsible for the behavioural and metabolic deficits. indeed, the observed early metabolic defects themselves might actually interfere with clearance of aβ and promote accumulation of detectable aggregates. the resultant aβ -expressing nematodes experienced a significantly shortened lifespan (fig.  e, supplementary table s ). we also determined nematode health-span by classifying nematodes into motility classes a, b, or c as defined in ref. . compared to controls, aβ -expressing nematodes showed reduced health-span (fig.  f ), as indicated by a lower percentage of highly motile (class a) from day to . aβ-expressing nematodes displayed neuromuscular defects and middle-aged onset of behavioural dysfunction. we further observed numerous signs of neuromuscular defects in the aβ -expressing nema- todes, including higher incidence of internal hatching (bagging ; fig.  a), defects in defecation that lead to con- stipation (fig.  b), lower rates of pharyngeal pumping (fig.  c), and abnormal head shake behaviour (fig.  d,e). bagging may occur rarely in wildtype nematodes as a result of age-related degeneration in the egg laying system, which requires proper formation and functioning of the vulva, vulval muscles and their innervating neurons . defecation and pharyngeal pumping similarly are neuromuscular events that are tightly regulated and carefully orchestrated by the nervous system , . we also noticed abnormally large oscillatory angle and irregular head shake frequency in the aβ -expressing nematodes (fig.  d). to quantify this behaviour, we calculated the sum of total oscillatory angle as the product between average angle of deflection and head shake frequency. we found a significant difference in this measurement of head shake behaviour in middle-aged aβ -expressing nematodes compared with controls (fig.  e). these abnormal oscillatory head movements, together with the higher inci- dence of bagging, defects in defecation and in pharyngeal pumping, indicate that neuronal aβ expression had broad detrimental effects on nematodes’ neuromuscular function. during routine nematode cohort maintenance a certain percentage of nematodes crawl off the side of culture plates and become lost (cannot to be located by the experimenter or found dried at side of plate) . we observed, during our early work with the aβ -expressing nematodes, that they had a more pronounced tendency to wander off plates than usually seen in controls. to investigate this behaviour further, we quantified nematode loss on fresh food plates and confirmed a significantly higher tendency of aβ -expressing nematodes to crawl out of the plate (fig.  a). to evaluate whether this abnormal wandering behaviour was indicative of a general failure in complex sensorimotor function, we conducted a ‘food race’ assay (fig.  b). during this assay, nematodes are placed on a fresh culture plate mm away from a food spot. nematodes explore the new environment and eventually sense the presence of food and track towards it ref. . aβ -expressing nematodes performed normally in this assay at a young age (day and ), but were significantly less likely to reach the food at middle age (day and , fig.  c). this observation reveals an age-related onset of behavioural phenotypes in aβ -expressing nematodes. atp reduction and etc complexes dysfunctions precede global metabolic failure in aβ-expressing nematodes. upon successful characterization of the age-related behavioural deficiencies in the aβ -expressing nematode, we proceeded to investigate the temporal relationships between the different compo- nents of mitochondrial dysfunction. we measured cellular atp levels, etc complex i and iv activities, and meta- bolic flux as components of mitochondrial functioning. among the different components, large decreases in atp level was the earliest event observed in the aβ -expressing nematodes, even before the onset of behavioural deficit in middle-age. compared to controls, aβ -expressing nematodes experienced significantly lower steady-state atp levels from a young age (fig.  a). on the other hand, deficiencies in etc complex i and iv were observed starting only from middle-age (fig.  b). www.nature.com/scientificreports/ scientific reports | : | doi: . /srep figure . a novel c. elegans ad model constitutively expresses low levels of full-length human aβ – and exhibits significantly shorter lifespan and reduced health-span. (a) relative expression levels of human aβ – mrna in aβ -expressing and control (day ) nematodes, normalized to c. elegans homolog of human actin (act- ) (***p < . ; n = replicates, with nematodes per replicate). (b) dna gel resolving the pcr fragment obtained from amplification of the full length mrna sequence. the expected full length aβ band size is bp. (c) immunoblot comparing human aβ – protein levels between aβ -expressing and control nematodes, in insoluble fractions, at different ages. the expected band size for aβ and α -tubulin is kda and kda respectively. (d) quantification of aβ band intensity obtained from the aβ -expressing nematodes of different ages (n = replicates, with approximately nematodes per replicate). (e) kaplan-meier survival curves of aβ -expressing and control nematodes. aβ -expressing nematodes had a significantly shortened lifespan (log rank test: p < . ; n = aβ -expressing and control nematodes). (f ) aβ -expressing nematodes had normal motility when young, but had a lower percentage of class a nematodes starting from middle age (day ) than controls (overall significance by two-way anova: ***p < . ; n = aβ -expressing and control nematodes). www.nature.com/scientificreports/ scientific reports | : | doi: . /srep we further evaluated metabolic flux in nematodes using a seahorse bioanalyzer, which enables the quantifica- tion of basal respiration rate, as well as maximal respiration rate and spare respiratory capacity, in the presence of carbonyl cyanide -(trifluoromethoxy) phenylhydrazone (fccp), a mitochondrial uncoupler, and sodium azide, an etc complex iv inhibitor (fig.  c) . fccp uncouples oxygen consumption from atp production by dissi- pating the proton gradient across the inner mitochondrial membrane, which in turn causes an increase in fuel utilization and oxygen consumption as cells attempt to re-establish the proton gradient . the difference in oxygen consumption during basal state and after fccp addition thus reveals the spare respiratory capacity of the mito- chondria. sodium azide inhibits most of the cellular respiratory processes and shuts down most oxygen consum- ing processes. azide was used to determine baseline drift due to processes that consume oxygen independently figure . aβ-expressing nematodes show signs of impaired neuromuscular behaviours. (a,b) compared to controls, there was a greater proportion of bagging (unpaired t-test: *p < . ; n = replicates, with – nematodes per replicate) and constipated aβ -expressing nematodes (overall significance by two-way anova: *p < . ; post-test: middle age, *p < . ; n = replicates, with – nematodes per replicate). (c) aβ -expressing nematodes experienced more severe age-dependent decline in pharyngeal pumping relative to control (overall significance by two-way anova: p < . ; post-test: young & middle age, ***p < . ; n = – nematodes). (d) angle of deviation, α , was measured relative to the central axis. illustrative head shake graphs for middle-aged control and aβ -expressing nematodes are shown. (e) middle-aged aβ -expressing nematodes exhibited greater cumulative oscillatory angle (product of angle of deflection and head shake frequency) than controls (overall significance by two-way anova: p < . ; post-test: middle age, **p < . ; n = – nematodes). age classification is as follows: young (day post-hatched), middle-age (day post- hatched), old (day post-hatched). www.nature.com/scientificreports/ scientific reports | : | doi: . /srep of cellular respiration. finally, the difference in oxygen consumption rate in the presence of fccp and azide was used as the maximal oxygen consumption due to cellular respiration. we found that while aβ -expressing nematodes had comparable basal respiration when young, middle aged, but old-aged aβ -expressing nematodes showed significantly suppressed basal respiration relative to controls (fig.  d). similarly, aβ -expressing nem- atodes had relatively normal spare respiratory capacity and maximal respiration at young and middle age, but significantly lower maximal respiration and spare respiratory capacity at old age (fig.  e,f ). given that atp and etc complex deficits were detectable in middle-aged aβ -expressing nematodes, while deficits in mitochondrial maximal respiration and spare respiratory capacity were observable only in old aβ -expressing nematodes, these data thus suggest that an energy crisis preceded the general metabolic failure in the aβ -expressing nematodes. discussion here we report the first c. elegans ad strain designed to constitutively express full-length human aβ – specifi- cally in neurons. the unc- promoter used is well-characterized and highly specific for neurones but we cannot entirely exclude the possibility that some aβ is also expressed in other tissues. however, most of the phenotypes observed are consistent with predominately neuronal expression. this strain suffered from shortened lifespan and reduced health-span, and exhibited neuromuscular and behavioural dysfunction including internal hatching, constipation, defects in pharyngeal pumping, abnormal oscillatory head movements and middle-age-onset sen- sorimotor deficits. the middle-age onset and gradual progression of behavioural deficits exhibited by this strain have allowed us to study the temporal relationships between mitochondrial dysfunction and behavioural deficits. consistent with a study showing early reduction of atp levels in pre-symptomatic transgenic ad mice , we found that atp deficit was an early event experienced by aβ -expressing nematodes, even before the onset of behavioural deficits and aβ aggregation. this sequence of events suggests that bioenergetic deficits in the aβ -expressing nematodes may be independent or causative, rather than as a consequence of aggregation. the large fall in atp level was followed by dysfunctions in etc complexes i and iv, which are well characterized features in human ad pathogenesis that have also been observed in the muscle-specific c. elegans strain overex- pressing human aβ . global metabolic failure, in the form of lower basal and maximal respiration, and decreased spare respiratory capacity, occurred only in old aβ -expressing nematodes. the sequence of events suggests that global metabolic failure in aβ -expressing nematodes is driven by mito- chondrial bioenergetic deficits and progressive complex i and iv dysfunctions. given that % of metabolic figure . middle-aged aβ-expressing nematodes exhibit a pronounced tendency to wander off secondary to deficits in complex sensorimotor function. (a) compared to controls, aβ -expressing nematodes were twice as likely to wander on food plates (unpaired t-test: **p < . ; n = replicates, with – nematodes per replicate). (b) sensorimotor function was tested using the ‘food race’ assay. between and nematodes were placed at a starting spot mm away from a food spot and the percentage of nematodes that successfully reached the food was scored after min. (c) compared to controls, aβ -expressing nematodes were significantly less likely to reach the food, both at day (early middle age) and day (late middle age) (overall significance by two-way anova: p < . ; post-tests: day , **p < . ; day , ***p < . ; n = replicates, with – nematodes per replicate). www.nature.com/scientificreports/ scientific reports | : | doi: . /srep energy is believed to be used to maintain ionic gradients required to sustain healthy neuronal function, at least in mammals , we believe that the large decrease in atp level may have also contributed to the behavioural deficits and neuromuscular dysfunctions observed in aβ -expressing nematodes. remarkably, we have detected significant metabolic effects in whole nematodes despite aβ expression at low levels in the neurons. our findings confirm earlier findings in a related muscle-specific c. elegans strain overex- pressing human aβ , , and support observations previously made in transgenic mice (reviewed by ref. ) and ad brains (reviewed by ref. ). this consistency suggests that aβ -driven metabolic and mitochondrial effects may be a fundamental feature of aβ toxicity that can be reproduced in organisms separated by large evolutionary distances. our findings have provided further evidence to the increasingly popular view that ad may be a metabolic neurodegenerative disease . aβ has been shown to induce hypometabolism (reduced energy metabolism) figure . atp reduction and etc complex deficits preceded global metabolic failure in aβ-expressing nematodes. (a) aβ -expressing nematodes had significantly lower atp levels than controls at middle (**p < . ; n = replicates, with nematodes per replicate) and old age (***p < . ; n = replicates, with nematodes per replicate). (b) complex i and iv enzymatic activities were significantly lower in middle- and old-aged aβ -expressing nematodes than in control (***p < . ; n = replicates, with nematodes per replicate). data were normalized to controls. (c) typical metabolic flux data obtained in c. elegans. (d) aβ -expressing and control nematodes had comparable basal respiration when young, but middle- and old- aged aβ -expressing nematodes showed significantly lower basal respiration relative to control (***p < . ; n = replicates, with nematodes per replicate). (e,f ) aβ -expressing nematodes had relatively normal maximal respiration and spare respiratory capacity at young and middle age, but significantly lower spare respiratory capacity and maximal respiration than control at old age (***p < . ; n = replicates, with nematodes per replicate). www.nature.com/scientificreports/ scientific reports | : | doi: . /srep in vitro , . proteins involved in energy metabolism have also been found specifically oxidized in the muscle-specific c. elegans strain overexpressing human aβ . there is also substantial evidence from transgenic mice , and human ad studies that links hypometabolism to ad – . given that mitochondrial dysfunction plays an important role in the pathogenesis of ad, early intervention with mitochondrial-targeted therapeutics, such as mitoq , , to delay the progression of early ad could prove a promising treatment. work aimed at exploiting our new nematode model for screening of putative ad therapeu- tics, especially early preventative treatment that specifically target mitochondria, is underway. materials and methods nematode strains and general study design. the bristol n (wild-type) strain were obtained from caenorhabditis genetics center. aβ – minigene from ref. was used, and cloned into the pti . plasmid which contains the unc- promoter to drive pan-neuronal aβ – expression. aβ – minigene-containing pti . vec- tor was co-injected with myo- ::yfp pharyngeal-specific fluorescence marker, both at a concentration of ng/μ l into the distal gonads of wild-type young adults. ultraviolet (uv) irradiation was used to facilitate array inte- gration into chromosomes. to exclude the possibility of unwanted mutation we outcrossed the strain four times, and independently created strains with the same construct. those independently created strains showed similar behavioral and biochemical phenotypes. a vector control strain with only myo- ::yfp was generated alongside with the transgenic nematodes, and used as control for subsequent experiments. all strains were grown at °c and maintained as previously described . all experiments used age-synchronized nematode obtained by hypochlorite bleaching. adult age groups were categorized as follows: ‘young’, day post-hatching, ‘middle age’, day post-hatching, ‘old’, day post-hatching. all behavioural studies were conducted under blinded conditions to minimize experimenter’s bias . except for lifespan and health-span studies, all other age-dependent experiments were carried out in the presence of μ m -fluoro- ′ -deoxyuridine (sigma-aldrich, st. louis, usa) to prevent progeny production. unless otherwise indi- cated, all experiments were carried out in at least two independent cohorts, producing consistent results. rna extraction and reverse transcription. nematode pellets ( nematodes) were snap frozen in liquid nitrogen and thawed three times. total rna was extracted using the rneasy micro kit (qiagen, venlo, netherlands), with dnase treatment, as per manufacturer’s instruction. cdna was synthesized using oligo-dt primer, with goscript reverse transcription system (promega, madison, usa), as per manufacturer’s instruction. real time polymerase chain reaction. for pcr using taqman system, taqman universal pcr master mix was used with customized gene assays ajx tp (abeta) and ce _s (act- : β -actin; applied biosystems, foster city, usa) were used with the (applied biosystems, foster city, usa). cycling conditions were °c × min, then °c × min, followed by cycles of °c × sec + °c × min. for pcr using sybr system, quantifast sybr green pcr kit (qiagen, venlo, netherlands) was used with self-design abeta primers (fp: ′ gat gca gaa ttt cga cat gat tca gg; rp: ′ tca agc aat gac aac tcc tcc c). cycling conditions were °c × min, followed by cycles of °c × sec + °c × min. all reactions were performed using a stepone rt-pcr system (life technologies, carlsbad, usa). dna gel electrophoresis and sequencing. dna fragments obtained from pcr were resolved on a . % agarose gel at v for min (bio-rad, hercules, usa). dna bands were visualized using an ecl imager (thermo fisher scientific, waltham, usa). for sequencing, dna samples obtained from pcr were purified using qiaquick pcr purification kit (qiagen, venlo, netherlands). single pass dna sequencing was performed by axil scientific ( st base, singapore, singapore). protein extraction and immunoblot analysis. approximately nematodes were homogenized in x ripa buffer (cell signaling, beverly, usa) containing % protease inhibitor cocktail (roche, basel, switzerland). after centrifugation, the supernatant was collected as the soluble fraction, while the pellet was re-extracted in m urea (sigma-aldrich, st. louis, usa) containing % protease inhibitor cocktail (roche, basel, switzerland). ice sonication followed by centrifugation was performed to obtain the insoluble fraction. protein separation and immunoblotting were performed as described in ref. with modifications. modifications include probing for aβ using anti-aβ antibodies e (covance inc., california, usa) at a : dilution and visualizing immune-positive aβ bands by enhanced chemiluminescence using the supersignal west femto kit (life technologies, carlsbad, usa). the membrane was stripped and reprobed with anti-α -tubulin (sigma-aldrich, st. louis, usa) at a : dilution for normalization. lifespan, health-span and neuromuscular function scoring. lifespan and health-span assays were conducted under blinded condition as described in ref. . nematode motility was used as a marker of health-span, using the abc scoring described in ref. . nematodes with progeny that hatched internally were scored as bagging . nematodes that lost their dark-colored intestinal appearance and showed disorganized intestinal arrangement were scored as constipated . for pharyngeal pumping assay, videos of nematodes were recorded at x magnification using a leica ic hd microscope system. number of pharyngeal pumps over a sec time interval was then counted for each nematode. for head shake measurement, videos of nematodes were recorded at x magnification using a leica ic hd microscope system. the average maximum angle of deviation from the central axis and the frequency of head movement from side-to-side were measured and their product was obtained as the sum of oscillatory angle. www.nature.com/scientificreports/ scientific reports | : | doi: . /srep behavioural assays. for the nematode loss assay, – nematodes were placed on mm agar plates next to their food and incubated for h. the percentage of nematodes that had crawled off the plates and had dried at the edge of plates was scored as lost. food race assay was conducted as described in ref. using mm ngm plate. biochemical assays. atp luminescence assay was performed as described in ref. using firefly lantern extract (sigma-aldrich, st. louis, usa). mitochondrial metabolic flux was measured using xf extracellular flux analyzer (seahorse bioscience, north billerica, usa), as described in ref. . for the measurement of etc complex enzyme activities, isolation of mitochondria and measurement of complex i and iv activities , were performed as described in ref. with approximately nematodes per replicate. this experiment was performed in only one cohort with three replicates, due to the large sample size needed. statistical analyses. all statistical analyses were performed in graphpad prism (san diego, usa). difference between nematode strains was determined using two-way anova analysis with post-tests for all age-related experiments, while an unpaired t-test was performed for non-age-related experiments. values were reported as mean ± standard error or mean (sem). p value of < . was considered significant. references . glenner, g. g. & wong, c. w. alzheimer’s disease: initial report of the purification and characterization of a novel cerebrovascular amyloid protein. biochem biophys res commun , – ( ). . grundke-iqbal, i. et al. microtubule-associated 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( ). . birch-machin, m. a., briggs, h. l., saborido, a. a., bindoff, l. a. & turnbull, d. m. an evaluation of the measurement of the activities of complexes i-iv in the respiratory chain of human skeletal muscle mitochondria. biochem med metab biol , – ( ). acknowledgements we thank the caenorhabditis genetics centre for the provision of worm strains and also the funding provided by ministry of education singapore (grant r- - - - and -t - - ), yale-nus start-up grant and nus graduate school for integrative sciences and engineering. author contributions s.f. and j.g. conceived and designed the experiments; s.f., e.t., l.f.n., c.-b.c., l.n.l. and s.y.t. performed the experiments; s.f., e.t., p.k.m., t.i., b.h. and j.g. analysed the data. s.f., e.t. and j.g. wrote the main manuscript. all authors revised the manuscript. additional information supplementary information accompanies this paper at http://www.nature.com/srep competing financial interests: the authors declare no competing financial interests. how to cite this article: fong, s. et al. energy crisis precedes global metabolic failure in a novel caenorhabditis elegans alzheimer disease model. sci. rep. , ; doi: . /srep ( ). this work is licensed under a creative commons attribution . international license. the images or other third party material in this article are included in the article’s creative commons license, unless indicated otherwise in the credit line; if the material is not included under the creative commons license, users will need to obtain permission from the license holder to reproduce the material. to view a copy of this license, visit http://creativecommons.org/licenses/by/ . / © the author(s) http://www.nature.com/srep http://creativecommons.org/licenses/by/ . / 	energy crisis precedes global metabolic failure in a novel caenorhabditis elegans alzheimer disease model
 	results
 	generation of constitutive pan-neuronal aβ – -expressing nematodes. 	aβ-expressing nematodes displayed neuromuscular defects and middle-aged onset of behavioural dysfunction. 	atp reduction and etc complexes dysfunctions precede global metabolic failure in aβ-expressing nematodes. 	discussion
 	materials and methods
 	nematode strains and general study design. 	rna extraction and reverse transcription. 	real time polymerase chain reaction. 	dna gel electrophoresis and sequencing. 	protein extraction and immunoblot analysis. 	lifespan, health-span and neuromuscular function scoring. 	behavioural assays. 	biochemical assays. 	statistical analyses. 	acknowledgements 	author contributions 	figure .  a novel c. 	figure .  aβ-expressing nematodes show signs of impaired neuromuscular behaviours. 	figure .  middle-aged aβ-expressing nematodes exhibit a pronounced tendency to wander off secondary to deficits in complex sensorimotor function. 	figure .  atp reduction and etc complex deficits preceded global metabolic failure in aβ-expressing nematodes. the roots of lca in switzerland - continuous learning by doing lca history the roots of lca in switzerland lca history: h o w it came about the roots of lca in switzerland - continuous learning by doing paul fink corresponding address: prof. dr. paul fink, tutilostr. b, ch- st. gallen, switzerland (former director of the empa st. gallen, senior professor for technology (emeritus) of the university of st. gallen/hsg) scientists and economists get interested in environmental impacts in the sixties, empa (eidgen ssische materialpri.ifungs- und -forschungsanstalt, d i i b e n d o r f and st. gallen) had its first c o n f r o n t a t i o n s with e n v i r o n m e n t a l p r o b l e m s . the water- pollution by detergents, the emissions in the air by the traf- fic and the packaging litter were the first things to be con- sidered. the economists at hsg (university of st. gallen- g r a d u a t e school of business, economics, law and social sciences) w e r e - also m o t i v a t e d by the p u b l i c a t i o n o f the club of rome - interested in the depletion of raw materi- als and integrated the factor natural resources in their eco- nomic system-model. empa as a research and testing institute had to develop methods of control and evaluation. the b i o d e g r a d a b i l i t y of detergents and control of car exhausts were the first en- vironmental tests implemented. the energy discussions on nuclear and alternative energies (energy scenario switzer- land) and the energy crisis subsequently b r o u g h t new actu- ality to the environmental p r o b l e m s . direct impulses for lca o r ecobalances (as was said at this time) were p r o - vided by the scarcity of oil d u r i n g the energy crisis a n d se- vere criticism against the p a c k a g i n g industry. it was said that m a n y products were o v e r p a c k e d and t h a t the prefer- ence of disposals was responsible for the mountains of waste and the missing capacities for landfill. the ecological challenge had a m o r e technical and scien- tific effect on empa and an economic and social a s p e c t on the hsg. the consequence was t h a t an integrated holistic view of the e n v i r o n m e n t a l s i t u a t i o n and its e v a l u a t i o n ac- cording to a sustainable d e v e l o p m e n t was needed. it was also evident t h a t technical or end of pipe s o l u t i o n s regu- lated by directives had to be c o m p l e t e d by m e a s u r e m e n t s at the sources. also for this postulate, lca seemed to become helpful. two fundamental research projects as r e p o r t e d above, e n v i r o n m e n t a l p r o b l e m s were no longer quite new. in , t w o different research p r o j e c t s were then started at empa. these t w o basic studies for l c a d e v e l o p m e n t had different goals and were therefore even allowed to go different ways and to put the main stresses differently. . the bus-study (bundesamt fiir umweltschutz) " o k o - bilanzen von packstoffen" was initiated by the govern- ment and had to establish a d a t a bank for the most im- p o r t a n t p a c k a g i n g materials: aluminium, glass, plastics, p a p e r and c a r d b o a r d , tin plate. this study ended in with the r e p o r t sru no. (schriftenreihe umwelt- schutz des bus). . the y o g h u r t - s t u d y was initiated by the industry (dairy, packaging, distributers) and had to c o m p a r e different types of y o g h u r t p a c k a g i n g systems in relation to tech- nical p e r f o r m a n c e , costs and c o n s u m e r ' s acceptance as the e n v i r o n m e n t a l impacts. the goals of this study re- quired a m u l t i d i s c i p l i n a r y research, so h s g / f a h (for- schungsstelle fi~r a b s a t z und h a n d e l , the m a r k e t i n g spe- cialists) and empa (natural science and technology) were entrusted. a r e p o r t on this topic was published in . the p r o b l e m s to be treated at this time were n o t quite new for empa, but the k n o w l e d g e was based more on informa- tive contacts t h a n on o u r own research work. empa re- p o r t e d on the e n v i r o n m e n t a l p r o b l e m s with packagings and on possibilities o r m o r e r e c o m m e n d a t i o n s on h o w to m a n - age them. the r e p o r t o f the club o f rome, the p u b l i c a t i o n o f r. moi,ler-we.','k "die kologische buchhaltung (ecologic b o o k k e e p i n g ) " , a study of the swiss a l u m i n u m foil m a n u - facturers on energy a n d p a c k a g i n g , and the energy-ethic p o s t u l a t e of danlel spreng were k n o w n and therefore played some influence on the s t a r t and p r o c e d u r e of these two re- search works. the bus-study on packaging materials the eidgen ssische k o m m i s s i o n fiir a b f a l l w i r t s c h a f t (fed- eral c o m m i s s i o n for refuse and w a s t e disposal) needed m o r e details c o n c e r n i n g the c o n t r i b u t i o n o f packages to the waste p r o b l e m , the d e p l e t i o n o f resources a n d the pollution. the bus was p r o j e c t - l e a d e r and assisted by a w o r k i n g g r o u p which discussed and d i r e c t e d the study, p e r f o r m e d at e m p a by werner that.mann and verena humbel. the goal was int. j. lca ( ) - ( ) � ecomed publishers, d- landsberg, germany the roots of lca in switzerland lca history to get by the g o v e r n m e n t and industry approved data re- lated to the environmental influences o f the main packag- ing materials. empa had to review and check all available d o c u m e n t s and information related to the need of energy and raw materials, the emissions to water, air and soil in connection with the production o f the packaging materials aluminum, glass, plastics, paper, c a r d b o a r d and tin plate. also proposals for an evaluation and weighting of the dif- ferent environmental impacts were required. the goal was reference i n f o r m a t i o n a b o u t the most used packaging ma- terials f r o m a c o m m o n viewpoint which should allow us to attain compatible values suitable for comparisons. the data are given for kg o f finished foils or sheets. such data are specific for materials and not for packaging. as a guideline for the m e t h o d o l o g y and as an important source o f data, bus gave the repa-study (resource and environmental profile analysis) o f the midwest research institute, kansas city. for that reason, the reports are in- fluenced by the situation in the us. further information was received from the swiss manufacturers of aluminum, glass and c a r d b o a r d and from the german plastic and tin- plate producers. all unit-processes beginning with the extraction o f raw materials a n d ending with the production of the packaging materials were recorded exactly as far as allowed the infor- mation o f the industry and in the literature. the input and o u t p u t o f each step was recorded and registered as energy and material flows. it was tiresome work to get compara- ble and c o m p a t i b l e values for all materials. the proposals for the aggregation and the interpretation o f the collected data was a remarkable and courageous step versus impact assessment. they were based on ecological directives on pollution and the scarcity-thesis of moll~.'r- wenk's ecological bookkeeping. the goal to give only one eco-index for each packaging material was too ambitious. n o consensus could be f o u n d for eco-weighting factors con- tributed to the different kind of impacts. the data banks therefore p r o v i d e d the following parameters for each pack- aging material: � total energy-equivalent expressed in a virtual thermal p r i m a r y energy � sum p a r a m e t e r s for the environmental impacts to the c o m p a r t m e n t s water and air, using the legal limits for calculating the so-called critical volumes spoiled by the relevant emissions and summing up all emissions � the total v o l u m e o f waste for landfill. the publication o f this data bank by bus was a milestone in the lca-history. there n o w exists a set of official eco- data o f the m a i n packaging materials a n d also directives o n h o w to evaluate the total impacts on air, water and soil (landfill resources). the critical volumes suggest a real pol- luted v o l u m e while t o d a y ' s impact assessments speak o f impact potentials. in the introduction to the data base, the authors accentu- ated the complexity relative to the use o f ecobalances, so that only experts in packaging should use it. unfortunately, it came just at the beginning of the application of the pack- aging data to some troubles and controversies. a practical example should explain the use of the data and demonstrate the possibility of ranking packages in a com- parison test. five different packages for i liter milk were compared: � a bag made of a plastic tube, polyethylene ( g) � a light plastic bottle, polyethylene ( g) � a brik-pak paper laminated with polyethylene ( g) � a glass bottle, returnable, and cycles ( g) � a plastic bottle, polyethylene ( g). using the eco-data of the relevant packaging material and the measured weights of the containers, the closures and the etiquettes, the energy-equivalents, the critical volumes o f water and air, and the waste volumes were calculated. the conclusion of this tcst seemed very simple: the five con- tainers could be classified in three groups: . the smallest influence on the environnlcnt showed the returnable glass bottles and the plastic bag. . the highest eco-impacts were found for the brik-pak and the plastic bottle. . the light plastic bottle had a position between the two extremes. the surprising fact o f this restllt was that at this time more than % o f the milk distributed in switzerland in liter containers was packed in brik-pak or similar containers. the media reported this sensational piece o f news: the swiss milk distribution was a flop! the producers and users of these discriminated packages protested and pointed to other studies made for sweden and germany which came to quite different conclusions. w h o had nonvaluable data? but it was not only the quality o f data, the reasons were in the system-boundaries and the sources for data as well. the bus values were only material specific while the others tested the whole packaging and distribution system. lca for milk packages done later on explained and confirmed this. the logistic differences are very remarkable between a multiway system with glass containers and a o n e w a y disposable plas- tic container. the bus data were strictly relevant only for the swiss market. thus, the data for glass is based on a highly ecologic-minded production technique. o n the other side, the paper data was compared with data from sweden o r g e r m a n y in an upper range. the publication of this bus data bank had a remarkable response. the ecobalancers were h a p p y to have officially approved values. the record of a m a x i m u m o f details de- scribing the different steps in the related technical proc- esses in the empa reports for each packaging material guar- anteed the needed transparency. the proposed method to int. j. lca ( ) lca history the roots of lca in switzerland evaluate the environmental impacts as sum parameters was estimated by all who are used to calculate in the manner of an engineer or a bookkeeper. in some way, this philosophy was further developed and refined by ahbe, braunschweig and mt ller-wenk in the sru report nr. "methodik fiir okobilanzen auf der basis kologischer optimierung (method for ecobalances on the basis of ecologic optimiza- tion)" edited by buwal (bundesamt ftir umwelt, wald und landschaft, formerly bus). this report proposes the calcu- lation of ecopoints, but not everybody agreed with the sum parameters of the critical volumes of water and air and there- fore neglected to practice this data bank. the yoghurt study toni, an important swiss dairy, was convinced that glass will be the packing material of the future thanks to its g o o d ecological properties. toni therefore propagated y o g h u r t in the glass instead in the polystyrene cup c o m m o n l y used. this marketing idea was sustained by the swiss glass manu- facturers. the glass industry developed successful eco-strat- egies and could convince the consumers that glass containers are the best packaging material for sustainable development. the other yoghurt producers and distributors found the polystyrene cups with an aluminum cover to be an optimal type of container for the distribution of yoghurt. there- fore, they decided to clear up this controversy by a neutral expertise c o m p a r i n g the combiglas (container o f b r o w n glass which could be reused, and voluntarily returncd with no deposit) against the disposable polystyrene cup. representatives of dairies, the glass and plastic industry and the distributors entrusted empa and the fah-institute (forschungsstelle absatz und handel) of the university o f st. gallen with an economic, technical and ecological study on the consequences of a change from the polystyrene cup to the glass container combiglas. in the period of this study, the energy crisis had brought the plastic market at risk. for this reason, alternatives to polystyrene were also tested: a cup of polypropylene and one of paper. the given goals made this study packaging and distribu- tion oriented. the total costs of a change including the en- vironmental consequences of the need for new installations and the acceptance by the consumers were discussed. the goal and scope of the lca, needed for the ecological part of the study, were influenced by the economic consequences and by the technical performance of the evaluated packag- ing variants. here, empa was confronted with quite another situation than it was for the bus data bank. the basic data for the materials, the packaging and logistic processes, and the dis- posal were taken from the literature or were provided by the industry. they were not so detailed by far as in the bus study. at the beginning, the industry was also very reserved in providing p r o d u c t i o n information. however, we suc- ceeded in getting much more information by discussing the literature data with them, so that we could correct older values in the literature, thus mostly reducing them. great discrepancies existed in the literature which were explained by different points of view and the lack of transparency. it was necessary to prove this by plausibility considerations. it was also important to make the literature data compat- ible and realistic. it is to say that these plausibility tests were based on the view and the thinking o f a chemical-en- gineer. the lca items were discussed with the representatives of industry and trade. this intensive contact with the project group was very positive for planning and establishing the lca. the environmental part of the study recorded the energy demand summed up over all steps in form o f thermal pri- mary energy in mj. the emissions were only discussed quali- tatively. since most emissions are linked to the energy in- put, a q u a n t i t a t i v e r e c o r d i n g o f emissions, e.g. in the criterion o f critical volumes, seemed to be more misleading than a purely qualitative record. also the depletion of re- sources was discussed. o f cot, rse, tile energy consumption became the most significant feature in this procedure. taking a retrospective look into this initial .ca-activity, it is evident that the need to debate ecological consequences of different distribution-systems showed many of the lca p~oblems for which we are searching solutions or a way to manage them. the importance o f a holistic approach was evident. only the discussion o f the whole distribution system could give a real picture of the expenditure and the benefit. the hn'mu- lation of the goals, that means the problems to be solved, is extremely decisive for the system boundaries, the data set to be recorded and the evaluation criteria. the packaging performance is influenced by the product, the production pro- cesses, the distribution and the consumption and must be in order before an ecological evaluation can be performed. only this gives a realistic answer to the interesting questions. the yoghurt study had to consider different subsystems: � the packaging materials and the design (form) and weight o f the container used � the problem "returnable versus disposable" � the expenditures for packaging, storing and distributing � the possibilities of waste management. the interlink of the subsystems and the target o f a com- plete record of all material and energy flows from the cra- dle to the grave lead to a high complexity which can only be reduced by adapting the system b o u n d a r i e s and the number of inputs and outputs to be registered. if such an adaptation to the goals is omitted, the task c a n n o t be ful- filled in a realistic time and at an acceptable price. thus, a decision was made to record the following items in the yo- ghurt study: int. j. lca ( ) the roots of lca in switzerland lca history � the energy c o n s u m p t i o n , including the feedstock energy, is related to a virtual thermic primary energy. based on t h e r m o d y n a m i c arguments, this expenditure was taken as the m o s t i m p o r t a n t (energy-ethic postulate o f d. spreng: all h u m a n activities for a given benefit should be linked with a minimal energy flow). at the period o f this study, the swiss energy scene was intensively discussed and an energy concept was elaborated. thus, the view- point o f the value o f the different kinds o f energy was also integrated. � pollution was only discussed qualitatively. the data dis- posable were incomplete. the emissions in the air were very closely linked to the energy forms used and the cho- sen energy scenario. the sum-parameters of the bus- study, the critical volumes, were judged to be too prob- lematic. t h e renunciation of a quantitative record was also given reason by the fact that pollution is widely regu- lated by law. � the availability o f the different raw materials was also discussed. the existing differences between the resources were found to be not so decisive so that one or another material should be substituted. the depletion of oil for the p r o d u c t i o n o f plastics therefore lays in an acceptable range. the evaluation and interpretation o f the results received considered that the calculated energy demands showed a remarkable deviation-range (about % were admitted). that was the reason w h y ranges instead of strong numeric values were c o m p a r e d . in addition, sensitivity tests were made in respect o f changing the design, reduction of weight and return, and reuse quotes o f the glass containers. the two tests mentioned last s h o w e d a distinct effect. glass or plastic, returnables o r disposables? the answer to these questions: both packaging systems lay in the same range in relation t o the technical performance and the envi- ronmental risks. a further severe finding was that even sci- entifically elaborated facts c a n n o t assure an open-minded discussion. the presentation o f the results o f the y o g h u r t study to the press and the consumers could not convince them that polystyrene cups are as g o o d for the environ- ment as glass containers. the glass was unanimously pre- ferred by the participants o f the information meeting. this confirms that a successful marketing for a product leads to bias and that c o m p l e x systems discussed and explained from different view points are hardly o r only in a misleading w a y understood by the b r o a d mass o f the population. the pub- lic reacts only t o eye-catching and simple messages, and such reactions are m o s t l y very general and rashly. a s i t u a t i o n t y p i c a l o f s w i t z e r l a n d the development o f l c a m e t h o d s in switzerland m a y be classified typical for the swiss mentality. swiss people are on one side said t o be extremely exact or even pedantic and seem to bear all details in mind. clear regulations and rules on h o w to do the w o r k are striven for. it is the job of an engineer or bookkeeper to quantify all things as far as pos- sible and to use a formula for calculating the risk. this mentality was the philosophy o f the bus data bank and the proposed sum parameters o f critical volumes and energy equivalents. ahbe, braunschweig and mollfr-wenk per- fected this trend by the creation o f the eco-points. on the other side, the extremely democratic thinking and respecting of minorities forces the swiss to take all differ- ent views and possibilities into consideration, a situation which often leads to compromises or pluralistic solutions. such a kind of lca work which is not only related to the potential environmental effects, but also strives for a tech- nical, economic and social feasibility was the yoghurt study, initiated by industry and trade and carried out by the empa and hsg/fah. this w a y to solve the problem is no more an ecobalance in the stricter sense, but rather a quality management including performance, economy and ecology. a result o f this thinking was the propagation of the opti- mal packaging model. the strong critics against packaging were a motivation to give a paper on "packaging in a gen- eral view" at a meeting o f the swiss packaging institute in may . compliments, but also rebuke made in relation to the packaging, were discussed. as a contrast to this black and white visualisation, a more differentiating and system- atic evaluation method for packaging systems was devel- oped. this optimal packaging model was characterized by three dices " p e r f o r m a n c e " , "expenditure" and "proving by use" the dice was taken as a symbol to express that every thing has more than only one side to look at. lca was therefore one aspect of "expenditure" aside from the costs or the infrastructure. the ecostrategy became one element o f the quality management. both o f these two typical swiss extremes of lca method- ology received a remarkable international response. the swiss data bank for packaging materials and the sum pa- rameters linked to them were used widely, but of course also criticised. for practical balancing work, these official data provided a trusting base. the integration o f lca in the quality management, and the statement that lca is an important and helpful, but n o t the only valuable element for realizing a sustainable development, b r o u g h t contacts and participations in inter- national expert groups. for the further development o f lca-methodology, the re- ported duality had two effects. it complicated the efforts for a b r o a d consensus in l c a - m e t h o d o l o g y and thereby hindered a too detailed standardisation o f ecobalances in a short time. o n the other side, the possibilities and limits of lca were seen clearly as well. the risk o f being blinkered in one's w o r k was banned. thus, the roots o f a scientific research can also influence the shape o f the tree and its fruits as result of the research. lnt. j. lca ( ) proceedings template - word a promising approach to safe, proliferation resistant production of nuclear power terry kammash department of nuclear engineering and radiological sciences, university of michigan, ann arbor, mi , usa, tkammash@umich.edu abstract with the world population reaching about billion by the midcentury, the requirement for carbon-free energy (estimated at terawatts) to meet the global needs will indeed be daunting. a sizable portion of this power is expected to come from nuclear sources fuelled by fission and/or fusion breeding. although a great international effort is currently underway aimed at producing pure fusion power, the fact remains that such reactors will initially be characterized by rather modest gain factors “q” (ratio of fusion power to injected power), putting in question their economic viability and potential impact on the energy crisis. it is well known, nevertheless, that fusion reactions are neutron rich and energy poor while fission reactions are energy rich but neutron poor. as a result, it occurred to many researchers over the past several decades that a fusion hybrid in which fusion neutrons are used to breed fissile material, thereby serving as a “fusion fuel factory” might very well address the impending energy shortage. in this paper, we take a somewhat different approach. we propose a system in which the fusion neutrons from a fusion reactor operating at q-value slightly larger than unity are used to drive an energy- producing blanket in which uranium- fissile material is bred from thorium- and simultaneously burned to produce energy. it will be a steady-state operating system with no criticality invoked, thus providing a measure of safety as well as potential elimination of proliferation hazards. we employ a simple, one-dimensional model to demonstrate that energy enhancement of - can indeed be obtained from such an approach using currently known technology. . introduction much has been written in recent years about the energy crisis that the world might face by midcentury when its population will reach billion and all nations will demand a middle class life style. recent studies (hoffert et al., ) have indicated that the world will need - tw of carbon-free power, while others (hoffert et al., ) have examined the various options for achieving this objective. although the international community is currently vigorously pursuing fusion power development, the fact remains that under the current plan, fusion will be unable to make a significant impact on the crucial midcentury energy requirements (manheimer, ). an estimate (nakiecenovic, grubler, and mcdonald, ) of the various world energy resources in terawatt years is given below. table . an estimate of world energy resources. source energy (tw yrs) fossil coal oil gas mined uranium - clearly, for large amounts of carbon-free power, not only is it likely that nuclear power will play a major role, but also breeding of nuclear fuel will be required (manheimer, ). since the mined uranium estimate is usually expressed in terms of the energy content of u , breeding makes available the energy content of u or th (in the case of the thorium cycle) which, in turn, could multiply the available energy by more than a factor of (van der zwann, ). breeding fissile material, therefore, lies at the heart of the problem, and it can be done via either fission or fusion and, in some instances, by accelerator- produced fast neutrons (carminati et al., ). typically two cycles of breeding are often mentioned, one has to do with breeding pu from u , and the other breeding u from th . in the interest of eliminating proliferation hazards of the raw fuel, i.e. the possibility of chemical separation of weapons material, we focus on the breeding of u . a fission breeder, whose technology is currently available, has the disadvantage of typically supplying only itself and a single other burner. it must also operate for a long time before sufficient fuel is bred, and it is not clear whether this approach can indeed supply enough fuel to satisfy midcentury energy requirements. the fusion breeder, though not available at this time, does have distinct advantages when made to work. its potential was first noted by such notable scientists as sakharov ( ) and bethe ( ) with the latter demonstrating that there is no “doubling time” with a fusion breeder, and that each such breeder can supply fuel to roughly burners. it may be interesting to note in this regard that a thermal reactor produces at most . neutrons per reaction (moir, ). since one is needed to continue the chain reaction, there is . left for other purposes. the reaction energy is mev, and this leads to × - neutrons per mev. a fast neutron reactor, on the other hand, produces at most . neutrons or . × - neutrons per mev. in the accelerator-driven fast neutron case, it yields neutrons, but it takes gev since the accelerator is typically % international symposium on the peaceful applications of nuclear technology in the gcc countries, jeddah strategic planning for introducing nuclear technology in the gcc countries. (session /no ) efficient, so it gives . × - neutrons per mev. a fusion reactor using deuterium (d) and tritium (t) produces . mev neutron and . mev alpha particle for a total energy of . mev. after multiplication in, say, thorium through (n, n) or even (n, n) reactions, each neutron produces at least one other since one is needed to breed tritium in order to keep the dt fusion reaction going. as a result, we note that fusion gives at least . × - neutrons per mev, and by this yardstick, fusion neutrons are in a sense the “cheapest” and could in fact have a great promise (manheimer, ). although the thrust of this paper is not fuel breeding per se, but rather energy production, it is clear that fusion-produced fast neutrons could indeed be utilized for this purpose. . concept description and analysis the proposed system, in its simplest form, consists of a cylindrical fusion plasma-containing chamber, surrounded by a blanket containing a uniformly distributed thorium- isotope. the plasma confinement device suggested for this application is the gasdynamic mirror (gdm) (mirnov and ryutov, ) in which the confining magnetic field is stronger at the ends (mirrors) than at the center, thereby allowing most of the plasma to be confined while being heated to ignition temperatures. the plasma in question will be a %- % mixture of deuterium and tritium ions, and their confinement in this magnetic configuration is based on the principle that the device length is much longer than the ion-ion collision mean free path. under these conditions, the plasma behaves much like a continuous medium – a fluid – and its escape from the ends is analogous to the flow of a gas into a vacuum from a vessel with a hole, hence the name gasdynamic mirror. with the plasma behaving like a fluid, its confinement in gdm is dictated by gasdynamic laws, which yield for the confinement time, τ, the value (kammash and lee, ) th m v lr =τ ( ) where is the mirror ratio (of magnetic field strength at the mirror to that at the center), l the length of the device, and the mean (thermal) velocity of the ions. it has been shown (nagornyj et al., ) that for a high aspect ratio gdm, i.e. one with mr thv >>prl where is the plasma radius, magnetohydrodynamic (mhd) modes have been found to be stable for large due to the presence of plasma in the expansion region of the magnetic mirror (nagornyi et al., ). moreover, it has been found that the magnetic configuration in the gdm is capable of supporting plasma with high pressure as reflected by the quantity β (defined as the ratio of plasma pressure to magnetic field pressure) with experiments (zhitlukhin et al., ) confirming mhd stability for both large and β (~ ). a schematic of the system of interest is displayed in figure , where effectively a section of the cylindrical chamber showing a fusion plasma with radius surrounded by a blanket of radius r is presented. pr mr mr pr as noted earlier, the gdm device considered here will have a large aspect ratio, i.e. >>prl , to ensure plasma stability; as a result, it is reasonable to treat the problem geometrically as one- dimensional, and assume that, on the average, the neutrons flow radially into the blanket. for a %- % dt mixture, the number of fast neutrons ( . mev) produced per unit volume per second is given by kammash ( ) in equation ( ). v n vnnn ptd σσ == ( ) where , are respectively the deuterium and tritium ion densities, the plasma density, and dn tn pn vσ the maxwellian averaged fusion reaction rate. for a dt plasma operating at kev temperature, vσ has a value of . × - cm /sec, and at a plasma density of , the number of neutrons generated per unit volume per second is about . × . as they enter the blanket, these neutrons will interact with the thorium atoms to produce u and also interact with the uranium atoms to cause fission. these processes are represented by the following equations: - cm =pn =−= nn dt dn fϕσϕσ γ ( ) and =+Σ+Σ−∇= sd dt dn fat ϕνϕϕ ( ) equation ( ) gives the steady state production of u atoms, as represented by the density n , where ϕ is the neutron flux emerging from the fusion plasma, n is the th density in the blanket, and γσ and fσ are respectively the thorium microscopic capture cross section and the u fast neutron fission cross section. in a steady-state operating system, the neutron flux is obtained from equation ( ) where it is assumed that the fast neutrons obey the diffusion equation shown, with d denoting the diffusion coefficient, atΣ the total (of th and u ) macroscopic absorption cross section, and fΣ the u macroscopic fast neutron fission cross section. the quantity ν represents the number of neutrons produced per fission (~ . ) and s the neutron source. equation ( ) readily yields nnn f ξ σ σ γ == ( ) where it has been shown (rubbia, ) that . ≈ξ , thereby giving ( ) . nn ≈ and also ; aataa Σ≈ΣΣ≈Σ ( ) international symposium on the peaceful applications of nuclear technology in the gcc countries, jeddah strategic planning for introducing nuclear technology in the gcc countries. (session /no ) blanket r figure . system geometry. equation ( ) can be cast in the familiar form ( ) =+∇ ϕϕ gb with s to be used as a boundary condition, and bg is the geometric buckling. combining eqs. ( ) and ( ), we get ( )[ ] =++Σ−Σ sdb gatf ϕν ( ) and further note that the multiplication factor “ ” can be written as effk gat f eff db k +Σ Σ = ν ( ) for the geometry under consideration, the buckling is given by r b g . ≈ ( ) where we have ignored the axial component due to the large aspect ratio assumption invoked earlier. the solution to eq. ( ) is ( ) ( ) ( )rbcyrbajr gg +=ϕ ( ) where and are the zero-order bessel functions, and a and c are the constants of integration. the boundary conditions of relevance in this case are that the flux is finite at the origin, and that it vanishes at the outer boundary of the blanket. in the first instance, we must set c = since j y ( ) −∞=→ ry thereby reducing the solution to ( ) ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ = r r ajr . ϕ ( ) where we recall that . is the first zero of the bessel function. furthermore, eq. ( ) readily shows that the flux vanishes at r = r as expected. the constant a in the above equation is determined from the condition that the neutron current is continuous at the plasma-blanket boundary, i.e. j ( p r r rsdr d dj p p π ϕ =−= ) ( ) with s being given by eq. ( ). thus, we find that d srr a p π . = ( ) and upon combining with eq. ( ), the final form of the neutron flux in the system can be expressed by ( ) ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ = r r j d rsr r p . . π ϕ ( ) noting that the power density can be expressed by dp ( ) enrp fd σϕ = ( ) where e is the energy per fission, we obtain the power produced per unit length as lp ( ) ( ) ( )∫ ∫≈= r r r ddl p drrpdrrpp ππ r rp blanket neutrons neutrons fusion plasma rp r plasma neutrons (a) upright view (b) side view international symposium on the peaceful applications of nuclear technology in the gcc countries, jeddah strategic planning for introducing nuclear technology in the gcc countries. (session /no ) where the approximation in the limits of integration is invoked as a result of the fact that generally . the above equation yields rrp << ( . . . ejn d srr p f p l σ π = ) ( ) where is the bessel function of the first order. if we assume, as rubia did, namely that as a result of averaging the cross sections over the neutron spectrum of the integrated flux, then the u density, , would be . × cm- assuming that the thorium density, , is that of solid state. moreover, if we let e = mev and consider the following parameters for the system, namely cm, j . nn ≈ n n =pr =r cm, , . ×=s . =fσ barns, ( ) . . =j , we find that gw/cm =lp if, on the other hand, we assume that the density ratio as expressed in eq. ( ) scales as the value of the cross sections evaluated at the fusion neutron energy of . mev, then we get - cm . . ×=×= − nn thereby yielding the more conservative result of gw/cm . =lp it is interesting to note from eq. ( ) that ( ) ~~ pppl nrrsrrp revealing the system parameters that can be readily varied in order to influence the power production in the system. the dependence on the plasma density, , is of special significance since it bears directly on the design and injection power requirements of the fusion component. pn a brief examination of the above results reveals that an energy enhancement of several orders of magnitude is obtained by utilizing the fissile material bred and burned in the blanket by the fusion neutrons. with this result, the system may be viewed as a fusion reactor with a very large q-value which, as noted earlier, is far from attainable from systems likely to be operable by midcentury or even later. this analysis, though simplified, does indicate that we can take a fusion reactor with a q-value of near unity, which may be readily achievable, and turn it into a major power producer by the approach suggested in this study. a preliminary design (kammash and tang, ) of a gdm fusion reactor, with effectively the plasma size and density employed in the above example, is found to be about meters long and supporting a q-value of about . . this length does indeed support the large aspect ratio and one-dimensionality assumptions invoked in this analysis, and if we further maintain that the blanket axial length is comparable, then it is clear that such a hybrid fission-fusion system can indeed produce large amounts of thermal power. at a thermal conversion efficiency of - %, this also means that very large amounts of carbon-free electric power in the tens of terawatts, as needed by midcentury, can be achieved by this approach. . conclusion we have demonstrated in this paper that the fast neutrons produced in a fusion reactor, operating at or near breakeven condition, can be used to generate large amounts of power in a surrounding blanket containing fertile material. uranium- is bred in such a blanket through the thorium- cycle by these neutrons, and also burned by them to produce energy. a simple, one-dimensional model is utilized to represent the steady-state operating system in which safe, proliferation-resistant, sizable energy enhancement can be achieved. it is shown that hundreds of gigawatts or even terawatts of electric power can be generated by this approach with only a small fraction needed to sustain the fusion reactor component of the system. . references [ ] bethe h., ( ), nuclear news, may , p. . [ ] carminati f. et al., ( ), cern/at/ - . [ ] hoffert m. et al., ( ), nature, , . [ ] hoffert m. et al., ( ), science, , . [ ] manheimer w., ( ), j. fusion energy, # , . [ ] manheimer w., ( ), j. fusion energy, , # , . [ ] manheimer w., ( ), j. fusion energy, # / , . [ ] mirnov v.v. and ryutov d.d., ( ), sov. tech. phys. letters, , . [ ] moir r., ( ), fusion, , . [ ] nagornyj v.p. et al., ( ), nuclear fusion, , . [ ] nakiecenovic, grubler, and mcdonald, ( ), global energy perspective, cambridge university press, p. . [ ] sakharov a., ( ), memoirs, vintage books, new york, p. . [ ] kammash t., ( ), fusion reactor physics, principles and technology, ann arbor science publishers, ch. . [ ] kammash t. and lee m.j., ( ), j. propulsion and power, , . [ ] kammash t. and tang r., ( ), am. inst. phys. proc., , staif conference, feb . [ ] rubbia c., ( ), aip conf. proc., , international conference on accelerator-driven transmutation technologies and applications, las vegas, july . [ ] van der zwann b., ( ), technological forecasting and social change, , . [ ] zhitlukhin a.m. et al., ( ), jetp letters, , . international symposium on the peaceful applications of nuclear technology in the gcc countries, jeddah strategic planning for introducing nuclear technology in the gcc countries. (session /no ) 	 . introduction 	 . concept description and analysis 	 . conclusion 	 . references study on relationship of energy consumption and economic growth in china physics procedia ( ) – - © published by elsevier b.v. selection and/or peer-review under responsibility of icapie organization committee. doi: . /j.phpro. . . international conference on applied physics and industrial engineering study on relationship of energy consumption and economic growth in china li zhang-wei,zheng xun-gang college of economic administration sichuan agricultural university ya’an, china abstract energy is one of the most basic materials of the national economy, which plays an important role in national productin and life. the relationship between energy consumption and economic growth has been a fascinating question since energy crisis in s of last century. this paper analyzes the relationship between energy consumption and economic development based on the var model using temporal series of china from to , then uses impulse response function and variance decomposition to portray the correlations between economic growth and energy consumption. the result shows that there exists a unidirectional causality from energy consumption to gross domestic product and energy consumption can observably promote the development of economy. © published by elsevier ltd. selection and/or peer-review under responsibility of [name organizer] keywords:energy consumption; economic growth; var model; impulse response function; variance decomposition . introduction the relationship between energy consumption and economic growth has been a fascinating question since energy crisis in s of last century. as a first priority issue, economic growth lies in a very important position both in developing and developed countries. there is no doubt that energy is one of the most basic material of the national economy, which plays an important role in national productin and life. from an economic point of view, the relationship between energy consumption and economic growth lies in two aspects: the growing dependence of economic growth on energy, and on the other hand, economic growth can promote energy technology advances and large-scale development and utilization of energy. scholars have done a lot of research on the relationship between energy consumption and economic grwoth: in [ ], referred that if economic growth granger causes energy consumption, it is not a energy dependence economy, and the negative impact of energy-saving policy to economic growth may be very small or not exist. in [ ], referred that if energy consumption granger causes economic growth, it is a available online at www.sciencedirect.com © published by elsevier b.v. selection and/or peer-review under responsibility of icapie organization committee. open access under cc by-nc-nd license. open access under cc by-nc-nd license. http://creativecommons.org/licenses/by-nc-nd/ . / http://creativecommons.org/licenses/by-nc-nd/ . / li zhang-wei and zheng xun-gang / physics procedia ( ) – energy dependence economy, and the reduction of energy consumption may affect economic growth. in [ ], referred that if there is no causality between them, and there isn’t a necessary link between energy policy and economic growth. in [ ], referred that if there is bidirectional causality between them, that is to say economic growth and the energy consumption are interdependent. in order to keep the adaptation of the two, the best combination of policy should be used to realize the coordinate development of economic growth and energy consumption. in [ ], referred that there is no causality between energy consumption and economic growth in malaysia, singapore and philippines; there exists a unidirectional causality from energy consumption to gross domestic product in india; there exists a unidirectional causality from economic growth to energy consumption in india; there is bidirectional causality between them in pakistan and taiwan of china. in [ ], comparatively analyzed cointegration of the united states and china's energy consumption and economic growth whose result shows that economic growth is the granger cause of the energy consumption growth both in the two countries. in [ ], looking at both sides of demand and production, investigated the causal relationship between energy consumption and economic growth in china during the period from to , whose result shows there exists long-run equilibrium relationship between gdp and energy consumption and no causality between them in the short run, bidirectional causality in the long run. in [ ], did the adf test and granger causality test, then used elastic analysis method to analyze the ralationship between the two, whose result shows energy consumption growth promotes economic growth of china, and in turn, economic growth is not the main factor that causes the energy consumption growth. in [ ], analyzed cointegration and granger causality between energy consumption and economic growth based on the data of china from to , whose result shows that there is bidirectional causality between them, but doesn’t have long-term cointegration. in [ ], referred that economic growth and energy consumption is long-term equilibrium through cointegration analysis and granger causality test based on the data of china from to , energy consumption is an important impetus of the stably growing economy, and economic growth in the past is energy needed economy, the current data doesn’t show the constraint of energy consumption to economic growth. studies suggest that the relationship between energy consumption and economic growth is different in different countries, and even if in the same country the relationship is different at different times. . the var model using economic theory to describe the relation between the variables couldn’t offer the strict definition for dynamic relation between the variables frequently, besides endogenous variables may also appear on both sides of an equation, which make the estimation and inference complicated. and nonstructural approach of multi-variable modeling is used to solve these problems. and the vector autoregression model is one of nonstructural approach of multi-variable modeling. a vector autoregression(var) is a set of k time series regressions, in which the regressors are lagged values of all k series. a var extends the univariate autogression to a list, or “vector,” of time series variables. when the number of lags in each of the equations is the same and is equal to p , the system of equations is called a var ( p ). in the case of two time series variables, ty and tx , the var( p ) consists of the two equations tptptptptt tptptptptt uxxyyx uxxyyy ( ) where the ’s and the ’s are unknown coefficients and tu and tu are error terms. in practical, we hope that lag p is large enough to reflect dynamic characteristic of model, on the other hand, the longer lag length is, the more unknown coefficients are, and the less degree of freedom is. so, there need to find a balance between lag length and degree of freedom. and lag length can be determined using either f-tests or information criteria, such as akaike information criterion, schwarz criterion. li zhang-wei and zheng xun-gang / physics procedia ( ) – . positive analysis the choosing of indexes and data taking into account availability and reliability of data, this paper selects the gross domestic product (gdp) of china as indicator which measures the total of economic growth, uses total consumption of energy (ec) as indicator which measures the consumption of energy. these two groups of indicator data all comes from the statistical yearbook of china from to , gdp is adjusted at ’s constant price according to the indices of gross domestic product, total consumption of energy (ec) is caculated on the basic of heat value equivalent, and all data are processed by logarithm in order to maintain the stability of data using eviews . . table the data of energy consumption and gdp year ec gdp adjustidgdp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . granger causality to assert a causal relationship between ec and gdp, we could analyze the relationship between lec and lgdp by using granger causality tests. table granger causality test null hypothesis: lag f-statistic probability conclusion lgdp does not granger . . accept li zhang-wei and zheng xun-gang / physics procedia ( ) – cause lec lec does not granger cause lgdp . . *** reject . . accept . . ** reject . . accept . . ** reject . . accept . . * reject . . accept . . *** reject notes:“*”,“**”,”***” indicates significance under %, % , % of the levels respectively. according to table , we can draw the conclusion: lec granger-causes lgdp at the %, % or % significant level, and lgdp does not granger cause lec when lag length is from one to five. this is true according to the status of china: energy is the bridge of other industries in national economy, its consumption will condition production scale of national economy to some extent; national economy can not be sustained growth without consumption of energy. energy consumption stimulates the economic growth of the entire society while economic growth doesn’t stimulate energy consumption. that may be caused by the non-renewable of some energy resourses, imbalance between energy supply and demand and inefficiency of energy consumption. establish of var models ) var lag order selection the results provide var models of value of lr , fpe ,aic, sc and hq from to the rd lags in table and * indicates lag order selected by the criterion which shows that most criterion select the lag order of var models is . table var lag order selection criteria lag logl lr fpe aic sc hq . na . - . - . - . . . . e- - . - . - . . . * . e- * - . - . * - . . . . e- - . * - . - . * notes: “*”: lag order selected by the criterion; lr: sequential modified lr test statistic (each test at % level), fpe: final prediction error; aic: akaike information criterion; sc: schwarz information criterion; sc: schwarz information criterion; hq: hannan-quinn information criterion ) var model . . lg l . . . . lg l . . . . lg l dp ec dp ec dp ec aic=- . sc=- . according to equation, we could conclude that lec has a positive effect on lgdp; and lgdp may have a little negative effect on lec. that means the relationship between them is unidirectional. so the var matrix performs granger causality tests to a certain degree. li zhang-wei and zheng xun-gang / physics procedia ( ) – impulse responses -. -. . . . . . . lec lgdp response of lec to cholesky one s.d. innovations figure . response of lec to one s.d. innovations -. -. . . . . . . lec lgdp response of lgdp to cholesky one s.d. innovations figure . response of lgdp to one s.d. innovations as seen in figure , lec to one s.d. innovations of itself makes an immediate response, the first phase is positive and about . , then the response extent increases till the sixth phase, which reaches the maximum, then decreases but stays positive. that means the consumption of energy is accelerated by itself , and on short term, the promoter action increases. the response of lec to one s.d. innovations of lgdp does not presented immediately, the first period response is , after that, the response extent decreases till minimum of the fifth period, then it increases, and keeps a stable status from the twelfth period but stays negative. that means with the development of economy, the consumption of energy maybe decrease which may be caused by the increasing of energy efficiency, imbalance between energy supply and demand and so on. as seen in figure , lgdp to one s.d. innovations of lec makes an immediate response, at about the sixth period reaches to the maximum, after that, the response extent decreases gradually but keeps positive for a long run. that means consumption of energy has significant positive effects on economic growth in the long term; lgdp to one s.d. innovations of itself makes an immediate response, at the second phase reaches the maximum, then the response extent decreases till the eighth phase, which reaches to the minimum, then increases to constringency. that means the stimulating effect of lgdp to itself decreases and comes to a negative influence, but finally approach to zero. variance decompositions it is defined as variance decomposition to separate the variation in an endogenous variable into the component shocks to the var for finding out information about the relative importance of each random innovation in affecting the variables in the var. and figure , figure are variance decomposition charts of lqczl and lgdp. li zhang-wei and zheng xun-gang / physics procedia ( ) – lec lgdp variance decomposition of lec figure . variance decomposition of lec lec lgdp variance decomposition of lgdp figure . variance decomposition of lgdp as seen in figure , the contribution to lec is mainly from itself, and the contribution from lgdp increases rapidly from the first to sixth period response, then stays a relatively stably status but in general the contribution is small. that means gdp is not the granger cause to energy consumption. as seen in figure , the contribution from lec to lgdp increases observably, and exceeds the contribution of lgdp to itself after the fourth period, and finally comes to a stable status from the twelfth period, which means the economic growth comes from the stimulating effect of itself at first, but as time goes on, the stimulating effect of energy consumption to economic growth is very more significant than that economic to itself. that is to say economic growth is mainly stimulated by the consumption of energy. . conclusions the empirical study of energy consumption and economic growth in china has shown that: the role of energy consumption in promoting economic growth is obvious and as time goes on, the role of energy consumption in promoting economic growth would be enhanced and finally to a stable level. in turn, economic growth is not the factor to promote energy consumption. these may be caused by the raising desire for the energy supply and the limited energy producing with the rapid development of our economy. meanwhile, there is a big gap of energy efficiency between china and the developed countries. so we can not simply increase the total consumption of energy to promote economic growth, but enhance the efficiency of energy consumption and develop the new energy to realize a green, sustainable development of economy. references [ ] abul m, m masih, rumi masih. “energy consumption, real income and temporal causality, results from a multi-country study based on cointegration and error correction modeling techniques,” energy economics, vol. , pp. - , january . [ ] fan xue-hong, zhang yi-xiang. “empirical analysis on the ralationship between energy consumption and economic growth based on econometrics model,” theory monthly, vol. , pp. - , december .(in chinese) [ ] han zhi-yong, wei yi-ming, jiao jian-lin, fan ying, zhang jiu-tian. “on the cointegration and causality between chinese gdp and energy consumption,” systems engineering, vol. , pp. - , june . (in chinese) [ ] huang min, he ying. “the model and empirical analysis of relationship between economic growth and energy consumption,” statistics and decision, vol. , pp. - , november . (in chinese) [ ] jumbe, charlesb l. “cointegration and causality between electricity consumption and gdp: empirical evidence from malawi,” energy economics, vol. , pp. - , january . li zhang-wei and zheng xun-gang / physics procedia ( ) – [ ] li xiao-jia, liu peng. “an empirical analysis for china’s energy consumption and economic growth,” soft science, vol. , pp. - , august . (in chinese) [ ] wu qiao-sheng, chen jin-hua, wang hua. “comparative analysis of the united states and china’s energy consumption and economic growth cointegration,” china industrial economy, vol. , pp. - , april . (in chinese) [ ] yu e sh, jy cho.i. “the causal relationship between energy and gnp: an international comparison,” journal of energy and development, vol. , pp. - , october . [ ] zhou jie-qi, wang tong-san. “energy consumption and economic growth in china-empirical study based on causality test and asymmetric cointegration approach”, journal of north china electric power university (social sciences), vol. , pp. - , october . (in chinese) doi: . /j.bbabio. . . s abstracts / biochimica et biophysica acta ( ) s –s however, under a range of pathological conditions no levels can rise to micromolar levels and disrupt a wide range of cellular processes. between these two extreme concentration ranges no can interact with mitochondria in ways that have been described as physiological or pathophysiological. the highest affinity target is cytochrome c oxidase. this talk will review this interaction and suggest that it has the potential to play a role in both no signalling and detoxification. no has also been shown to interact with lower affinity with mitochondrial cytochrome c in both its reduced and oxidised forms. previous studies have indicated that no can oxidise cytochrome c at physiological ph. we show that most of this oxidation is not caused by direct reactions of no, but instead by a reaction product of no and oxygen, most likely no . in contrast the reaction of no with oxidised cytochrome c is a direct, reversible binding. intriguingly in the presence of cardiolipin no can also bind reduced cytochrome c with high affinity at neutral ph. we will describe these interactions and comment on their biological relevance. doi: . /j.bbabio. . . s / mitochondria and reversible apoptosis guy c. brown department of biochemistry, university of cambridge, uk e-mail: gcb@mole.bio.cam.ac.uk apoptosis has been considered as a form of cell death, to which a cell is irreversibly committed once cytochrome c is released from the mitochondria. however, apoptosis can also be regarded as a means of signalling to phagocytes, which may in principle be reversible up to the point of phagocytosis. we find that mitochondrial cytochrome c release does not inevitably commit a cell to death because if the cell reduces the cytosolic cytochrome c then caspase activation is blocked. similarly caspase activation does not inevitably commit a cell to death, because the caspases can be inactivated by endogenous oxidants. phosphatidylserine flip to the outer leaflet of the plasma membrane is also a reversible process, as long as phagocytes are not present to eat the cell. we find that many aspects of apoptosis are fully reversible in neurons. this leads to the conclusion that apoptosis can (in some circumstances) be reversible and is not always a form of cell death. doi: . /j.bbabio. . . s / ischemic preconditioning invokes multiple mechanisms of nitric oxide and reactive oxygen signaling at the mitochondrial level paul s. brookes department of anesthesiology, university of rochester medical center, rochester, ny, usa e-mail: paul_brookes@urmc.rochester.edu ischemic preconditioning (ipc) is a phenomenon in which short cycles of ischemia and reperfusion (ir) can protect organs such as the heart and brain from prolonged ir injury. mounting evidence suggests that both mitochondria and nitric oxide play critical roles in ipc signaling, although the exact biochemical mechanisms underlying cardioprotection are poorly understood. we have identified novel biochemical events involving reactive oxygen and nitrogen species, which may contribute to the modulation of mitochondrial function in ipc: ( ) s-nitrosation and reversible inhibition of respiratory chain complex i. ( ) activation of mild uncoupling via the generation of no derived electrophilic lipids (nitro-alkenes) and their post-transla- tional modification of mitochondrial carrier family proteins. ( ) endogenous generation of mitochondrial k+atp channel agonists and complex ii inhibitors, via redox reactions involving krebs' cycle intermediates. together, it is thought that these pathways all act to diminish mitochondrial ca + overload and ros generation at reperfu- sion, thereby limiting the opening of the permeability transition pore. a brief outline of the key findings in support of these novel signaling pathways will be discussed. doi: . /j.bbabio. . . (s ) mitochondria and reactive oxygen containing species symposium abstracts (poster and raised abstracts) s . mild uncoupling reduces oxidative stress in intact cells alexander m. wolf, sadamitsu asoh, ikuroh ohsawa, shigeo ohta department of biochemistry and cell biology, institute of development and aging sciences, graduate school of medicine, nippon medical school, japan e-mail: awolf@nms.ac.jp “mild uncoupling”, the introduction of a limited proton conduc- tance into the mitochondrial inner membrane, has been demonstrated to greatly reduce reactive oxygen species (ros) production in isolated mitochondria. on the other hand, it will also increase energy consumption to maintain the mitochondrial membrane potential, and cells need energy in the form of nadh to maintain the cellular protein machinery in the normal, reduced state. for this reason it has been a subject to debate whether mild uncoupling is a viable strategy to reduce oxidative stress in intact cells and ultimately in vivo, or whether the increased energy expenditure might have detrimental effects. using a redox-sensitive green fluorescent protein (rogfp ) targeted to mitochondria of pc cells, we found that mild uncoupling using low concentrations of chemical uncouplers fccp or dnp indeed reduced oxidative stress, whereas strong uncoupling caused oxidation of rogfp , indicating that the beneficial effects of uncoupling are limited to a certain range of membrane potential, and that uncoupling beyond this range will increase oxidative stress probably due to energy crisis. this leads to the conclusion that while mild uncoupling might be beneficial under some circumstances, it is a dangerous strategy since the safe range of uncoupling will probably depend on cell type and metabolic state. doi: . /j.bbabio. . . s . the role of reactive oxygen and nitrogen species in the pathogenesis of acute renal failure egor plotnikova, anastasia chupyrkinaa, alena vasilevaa, aleksandr kazachenkob, vladimir kirpatovskyb, dmitry zorova aa.n. belozersky institute, moscow state university, moscow, russia bresearch institute of urology, moscow, russia e-mail: plotnikov@genebee.msu.ru the aim of this work was to study mechanisms of acute renal failure (arf) development in kidney survived ischemia or mioglobi- nuria (rabdomyolysis). experimental model of those pathologies showed that days after ischemia or induction of rabdomyolysis, the levels of urea, creatinine and cell death markers increase. such kidney malfunctioning can be caused by tubular epithelium destruc- tion. in our experiments, lipid peroxidation products accumulated in kidney and total antioxidant activity of blood are decreased. also the level of nitrite in blood serum was increased indicating the activation of no production. analysis of ros- and no-production in kidney cells revealed amplification of the production of these radicals. we http://dx.doi.org/doi: . /j.bbabio. . . http://dx.doi.org/doi: . /j.bbabio. . . http://dx.doi.org/doi: . /j.bbabio. . . http://dx.doi.org/doi: . /j.bbabio. . . mailto:gcb@mole.bio.cam.ac.uk mailto:paul_brookes@urmc.rochester.edu mailto:awolf@nms.ac.jp mailto:plotnikov@genebee.msu.ru international journal of engineering & advanced technology (ijeat) international journal of engineering and advanced technology (ijeat) issn: – , volume- , issue- s , september published by: blue eyes intelligence engineering & sciences publication retrieval number: f s / ©beiesp doi: . /ijeat.f . s  abstract: the need for interconnected power system is increasing day by day because of continuous growth of electrical energy demand and to transmit electric power to remote places at minimum cost and minimum losses. with the operation of power system in interconnected manner, maintaining the system security is difficult task i.e. whenever a disturbance occurs, the system undergoes stability problems. even though conventional energy sources are available, electrical engineers prefer renewable energy sources integration because of energy crisis and pollution problems related to the former, one such renewable energy source is wind power. wind energy has major share in renewable energy sources because of its abundant availability in the nature. whenever wind generators coupled to the power system, the system exhibits drooping voltage characteristics and this situation becomes worse during faults. this condition can be neutralised with facts (flexible ac transmission system) devices, one such facts device is statcom (static synchronous compensator). statcomsupports reactive and real power exchange and also improves transient stability of the system because of its superior characteristics and quick response. in this paper a bus wind farm integrated test power system is taken and stability studies are done. since, wind farm is integrated with the system whenever a fault occurs, overall system stability is reduced i.e. the conventional synchronous generators can withstand it, whereas the wind generators can’t. so to enhance the transient stability of the system, a statcom is installed and the system behaviour is observed. keywords : statcom, wind generator, transient stability. i. introduction power system dynamics is also called as power system stability. today’s power systems are widely interconnected which results in operating economy and reliability problems. interconnection of power system leads to stability problems which became a challenging task for the engineers to maintain the system security. so, power system stability has become an important study in system security. power system stability is described as the maintenance of synchronism before and after a disturbance in the system. here, the disturbance in the sense a fault or sudden load change or switching operation. the concept of stability was first discovered in .in ’s the analog computers were used to simulate the interconnected power system. the first digital computer program of stability was prepared in . revised manuscript received on september , . * correspondence author mutyala nagababu, pg scholar, department of eee, anucet, acharya nagarjuna university, guntur(dt), andhrapradesh, india r.s. srinivas, assistant professor,department of eee, anucet, acharya nagarjuna university, guntur(dt), andhra pradesh, india polamraju.v.s.sobhan, associate professor, department of eee, vfstr, vadlamudi, guntur, india m.subbarao, assistant professor, department of eee, vfstr, vadlamudi, guntur, india the study of stability problem was concerned with developing the mathematical model of the power system, for this we have to solve the series of non-linear differential and algebraic equations, which doesn’t have a unique solution. so, numerical methods are to be adopted for solving them. in electrical power generating stations many alternators are connected to the bus having same phase sequence and frequency. so to operate the system in stable, we have to synchronize the bus with all the other incoming lines and generators. so, the power system stability is also referred as synchronous stability i.e. the ability of the system to reach its equilibrium point after the system has undergone some transience [ ]. ii. literature survey now a days electrical engineers are operating the interconnected power system with renewable energy sources rather than the conventional energy sources because of pollution and energy crisis of later [ ]. the availability of wind power is abundant in nature making its share huge in renewable energy sources. but wind power integration leads to reactive power and voltage problems in the system i.e. system exhibits drooping voltage characteristics and because of its controlling difficulties leads to stability problems [ ]. whenever a fault occurs in the system, the conventional generators can with stand it but the wind generators cannot sustain it and thereby reducing the relative stability of the system [ ]. with recent developments in semiconductor technology and the invention of facts devices, the problems related to stability, power quality and reactive power can be eliminated [ ]. different facts devices like static synchronous compensator (statcom), fixed capacitors, tcr (thyristor controlled reactor), tsc (thyristor switched capacitor) etc. helps in maintaining voltage stability and improves the power transfer capability. but upon all the shunt facts devices, statcom gives best results, because of its quick response time, ability of reactive and real power exchange and superior characteristics [ ]. this paper presents a power system transient stability analysis on a wind farm integrated power system (modified from ieee bus system) and how its transient stability is improved with statcom.the system is used and simulated on matlab. iii. test and simulations for testing and simulation in matlab two bus wind farm integrated power systems are used. the first system is without statcom (fig. ) and second system is with statcom (fig. ). transient stability improvement of wind farm integrated power system using statcom mutyala nagababu, r.s. srinivas, polamraju.v.s.sobhan, m.subbarao transient stability improvement of wind farm integrated power system using statcom published by: blue eyes intelligence engineering & sciences publication retrieval number: f s / ©beiesp doi: . /ijeat.f . s figure : test system with wind farm the above system is modified by installing a statcom at bus keeping all the parameters same, as shown in the fig. .these models are used to study and compare the behaviour of system with and without statcom under transient condition such as three phase fault. the system consists of loads, transmission lines and generators. the above models are the classical representation of power system which are of second order systems. the wind farm is modelled using squirrel cage induction generator [ ]. figure : test system with statcom and wind farm the following are the data for different elements [ ]. table. . generator data generator rated mva . kv . . xd(pu) . . . xd’(pu) . . . xq(pu) . . . xq’(pu) . . . xl(pu) . . . stored energy at rated speed mw-s mw-s mw-s table. . line data line r(pu) x(pu) b(pu) - . . . - . . . - . . . - . . . - . . . - . . . table. . transformer data transformer kv . / / . / z(pu) . . . table. . load data load a b c kv p(mw) q(mw) table. . data for scig variables values kv . mw generator inertia . stator resistance(pu) . stator inductance(pu) . rotor resistance(pu) . rotor inductance(pu) . table. . statcom data variables values kv mva vref(pu) . dc link voltage kv dc link capacitance . f iv. results and discussions the systems in the fig. and fig. are simulated in the matlab.the results obtained from the system with and without statcom have been compared to identify the transient stability enhancement approached using the statcom. rotor angle deviations of synchronous generators a three phase symmetrical fault is created at bus to study the power system transient behaviour which is of self-clearing type and lasts for . sec. from to . sec. due to which the rotor starts oscillating from sec. the peak value of first swing of relative rotor angle deviation for the machines & without statcom is . ° and with statcom is . ° and for the machines & the peak of first swing has reduced to . ° from . °. international journal of engineering and advanced technology (ijeat) issn: – , volume- , issue- s , september published by: blue eyes intelligence engineering & sciences publication retrieval number: f s / ©beiesp doi: . /ijeat.f . s figure .realative rotor angle deviations of machines & figure . realative rotor angle deviations of machines & speed deviation of wind generator with the installation of statcom the peak of first swing of rotor speed deviation of wind generator has reduced to . rad/sec from . rad/sec. since the statcom is connected at bus which is near to machine , the swing of machines & has reduced more, thereby improving the transient stability of the overall system. figure .rotor speed deviation of wind generator voltage profile since a three phase symmetrical fault occurs in the power system, the voltage magnitude at the bus is reduced. with the introduction of statcom the systems voltage profile became flat, thereby making the system to settle quickly i.e. system recovers from fault quickly with the introduction of statcom at bus . figure .voltage magnitude profile at statcom bus figure .voltage magnitude profile at statcom bus with zoomed y-axis reactive power the reactive power demand at bus without statcom is . pu, whereas with the introduction of statcom the demand has reduced to . pu. figure .reactive power at statcom bus v. conclusions it was noticed that integration of wind generator to the interconnected power system leads to the drooping voltage characteristics because of the high reactive power demand by wind generator and the conventional synchronous generators can with stand the faults without tripping off, but the wind generators can’t with stand the fault, thereby reducing the overall relative transient stability of the system.statcom has the capability of improving the transient stability of system because of its superior characteristics and quick response time. this paper investigated how the transient stability of the wind farm integrated power system can be improved by installing statcom in the system. simulation studies were done in matlab simulink to denoteand compare the transient stability of system integrated with wind farm, with and without statcom. the obtained results show that the system with statcom settles quickly and the reactive power demand of the wind generator was reduced. with the installation of statcom, the first peaks of relative rotor angle oscillations of synchronous generators and wind generator were reduced, thereby enhancing the transient stability of the power system. more over the voltage profile of the power system with statcom is flat when compared to the system without statcom. transient stability improvement of wind farm integrated power system using statcom published by: blue eyes intelligence engineering & sciences publication retrieval number: f s / ©beiesp doi: . /ijeat.f . s references . modern power system analysis by dp kothari & ig nagrath. the mc-graw hill companies. third edition. . karunya, l., p.harini, ., s.iswarya, . & a.jerlin, . ( ) emergency alert security system for humans. international journal of communication and computer technologies, (supplement ), - . doi: . /ijccts/ .sp . . “simulation and analysis of wind farm reactive power and voltage problems based on detailed model.” yuan xiaodong , wu zhi , china international conference on electricity distribution. . “effect of grid-connected dfig wind turbines on power system transient stability.”wei qiao, student member, ieee, and ronald g. harley, fellow, ieee . "optimal power flow by newton method for reduction of operating cost with svc models." . international conference on advances in computing, control, and telecommunication technologies. . ieee, . . “effectiveness of facts devices for power system stability enhancement.” sanjiv kumar, dr. narendra kumar, international journal of advances in engineering sciences vol. , issue , april, . . mv ngo tien hoa,high speed and reliable double edge triggered d- flip-flop for memory applications”,journal of vlsi circuits and systems, ( ), - , . https://www.mathworks.com/help/physmod/sps/examples/initializing-a - -bus-network-with-the-load-flow-tool-of-powergui.html biomass energy utilization in rural areas may contribute to alleviating energy crisis and global warming: a case study in a typical agro-village of shandong, china renewable and sustainable energy reviews ( ) – biomass energy utilization in rural areas may contribute to alleviating energy crisis and global warming: a case study in a typical agro-village of shandong, china y.h. zheng a,*, z.f. li b,c, s.f. feng b, m. lucas d, g.l. wu b, y. li b, c.h. li b, g.m. jiang a,b,* a state key laboratory of quantitative vegetation ecology, institute of botany, the chinese academy of sciences, nanxincun, xiangshan, beijing , china b state key laboratory of crop biology, college of agronomy, shandong agricultural university, taian, shandong , china c taishan academy of science and technology, tai’an, shandong , china d rheinisch-westfalisch technische hochschule, aachen university, aachen , germany contents . introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . energy status in rural china . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . energy policy of the chinese government . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . biomass resource in rural china. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . livestock development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . biogas production and utilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . improved biogas digester and biogas production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . biogas cooking stoves and illuminating lights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . materials and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . natural and socio-economic backgrounds of study area. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . a r t i c l e i n f o article history: received may accepted july keywords: biogas ‘‘bread’’ forage crop residues energy crisis global warming a b s t r a c t a biomass energy exploration experiment was conducted in jiangjiazhuang, a typical agro-village in shandong, china from to . the route of this study was designed as an agricultural circulation as: crops ! crop residues ! ‘‘bread’’ forage ! cattle ! cattle dung ! biogas digester ! biogas/digester residues ! green fertilizers ! crops. about . tons of crop residues are produced in this village each year. in , only two cattle were fed in this village and . % of the crop residues were used as forage. about . % crop residues were used for livelihood energy, . % were discarded and . % were directly burned in the field. not more than three biogas digesters were built and merely m biogas was produced a year relative to saving . tons standard coal and equivalent to reducing . tons co emission. a total of us$ profits were obtained from cattle benefit, reducing fossil energies/chemical fertilizer application and increasing crop yield. after years experiment, cattle capita had raised gradually up to and some . % crop residues were used as forage. the percentages used as livelihood energy, discarded and burned in the field decreased to . %, . % and . %, respectively. biogas digesters increased to and , m biogas was fermented equal to saving . tons standard coal and reducing . tons co emission. in total us$ , profits were obtained in . in addition, about . tons green fertilizers were produced from biogas digesters and applied in croplands. the results suggested that livestock and biogas projects were promising strategies to consume the redundant agricultural residues, offer livelihood energy and increase the villagers’ incomes. biogas production and utilization could effectively alleviate energy crisis and co emission, which might be a great contribution to reach the affirmatory carbon emission goal of the chinese government on climate conference in copenhagen in . � elsevier ltd. all rights reserved. contents lists available at sciencedirect renewable and sustainable energy reviews j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / r s e r * corresponding authors at: state key laboratory of quantitative vegetation ecology, institute of botany, the chinese academy of sciences, nanxincun, xiangshan, beijing , china. tel.: + ; fax: + . e-mail addresses: zhengyanhai @ .com (y.h. zheng), jianggm@ .com (g.m. jiang). - /$ – see front matter � elsevier ltd. all rights reserved. doi: . /j.rser. . . http://dx.doi.org/ . /j.rser. . . mailto:zhengyanhai @ .com mailto:jianggm@ .com http://www.sciencedirect.com/science/journal/ http://dx.doi.org/ . /j.rser. . . y.h. zheng et al. / renewable and sustainable energy reviews ( ) – . . ‘‘bread’’ forage processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . experimental design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . data collection and recalculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . nutrient parameters analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . biogas production and energies transforming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . economic benefit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . statistical analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . crop residues distribution and livestock development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ‘‘bread’’ forage nutrition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . biogas production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . green fertilizer production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . economic benefit and future perspectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . introduction energy crisis and global warming are considered as two severe problems worldwide [ , ]. scientists have been in search of renewable and sustainable energies, at least in part, substituting fossil energies for a long time [ , , ]. some reports indicate that biomass energy remains the primary source of energy for more than half the world’s population, and accounts for % of the total energy consumption in the world [ , , ]. by the contribution of biomass to global energy will fluctuate from to ej y� which is about % of the global primary energy supplication [ , , ]. biomass energy utilization has already been ranked in national energy strategies in china [ ]. . . energy status in rural china china, as the biggest developing country in the world, has about . billion people, and more than % of the nation’s population lives in rural areas, meeting most of their energy requirements (for domestic needs) from traditional biomass fuels over the past decades [ , ]. the major sources of traditional biomass are crop residues and firewood and their share in energy supply is approximately % [ ]. in the past, villagers’ per capita energy consumption was very low, mostly for cooking and water heating. annually primary energy consumption in was , mtce and the percentage of biogas energy in total energy consumption was around . % [ ]. however, in the recent years, biomass fuels were used less and less year after year in rural china. instead, coal, natural gas and electricity consumptions are significantly and rapidly increased in their energy supply with the improvements of their life levels. total primary energy consumption in reached , mtce but only . % was biogas energy [ ]. energy competition has been existing between rural and urban areas of china. energy crisis and greenhouse gas emissions will become more serious in the near future [ ]. . . energy policy of the chinese government energy development is a major constraint for a sustainable development in developing countries including china [ , ]. fossil energy (coal, natural gas, etc.) utilization maintains low energy use efficiency and emits huge amount of greenhouse gases. clean energy (water energy, wind energy, solar energy, etc.) production is considered by the policy makers, for instance by ‘‘china renewable energy law’’ [ ], ‘‘china saving energy law’’ [ ]. however, clean energy projects move very slowly in the past years. the major stumbling block is lack in terms of capital investment since clean energy development programs are highly capital intensive. traditionally these programs have been implemented with support or cooperation with the abroad companies. even then the achievements made in this sector have not been able to cope with the growing demand for energy services, in terms of both quality and quantity. in response to offer renewable and sustainable energies and reach the goal of alleviating greenhouse gases emission, biomass energy produc- tion and utilization (biogas production, bioelectricity generation, etc.) in rural areas has been highly taken into account by the chinese government. . . biomass resource in rural china biomass resources include various natural and derived materials mainly categorized as agricultural residues, wood and wood wastes, animal dung, municipal solid wastes [ , ]. in this study, we mainly focused on agricultural residues. approximate land use for agriculture is . % of the total land area of the country [ ]. agricultural residues contribute significantly to the biomass sector. about % of traditional biomass energy is supplied from major crop residues such as maize and wheat stalks. large amount of residues are produced by soybean, peanut, cotton, etc. liu et al. [ ] reported that china produces about million tons of crop residues each year. half of the crop residues come from east and central south of china, including shandong province. among those crop residues, corn, wheat and rice account for nearly % of the total crop residues. unfortunately, only small parts of crop residues ( %) are used for forage, the large parts ( %) are used by farmers as livelihood energy or discarded or directly burnt in the field. a huge amount of biomass is wasted or used with pretty low efficiency. therefore, a study on high-efficiency utilization of crop residues in rural china is very urgent. . . livestock development traditionally, cattle are important animals to meet humans’ requirements of meat and milk which were mostly pastured in the north steppe of china, such as inner mongolia. some reported that the livestock (cattle and sheep) capita have exceeded the high- points of grassland capacity in those areas, as a result the grasslands have been seriously degraded [ , ]. it is not a sustainable and ecological grassland management if the cattle and sheep livestock is being continuously increased in those pasture areas. by contrast, there is a plenty of nutrient forage (crop residues) being wasted in agricultural areas [ ]. the development potential of livestock will be much larger in agricultural areas than in pasture areas of china [ ]. [(fig._ )td$fig] fig. . biogas light used in farmers’ household corridor. y.h. zheng et al. / renewable and sustainable energy reviews ( ) – . . biogas production and utilization . . . improved biogas digester and biogas production biogas production has been established for three decades in rural china. there have been about million household digesters and biogas stations installed until the end of [ ]. however, in the past, biogas digester output was very low due to improper construction and lack of producing technologies [ , ]. most of the biogas digesters were built aboveground which was to cool for fermentation when the atmospheric temperature was low. some of them could not produce enough biogas for cooking in late fall and winter time. in addition, biogas production was low also due to the fact that agricultural residues have being directly filled in biogas digesters without livestock pre-digestion. improved technologies in building biogas digesters and livestock development were involved in this study. biogas digesters were built underground (dome type), they could effectively maintain high temperature when the atmospheric temperature was low. on the other hand, biogas digesters located behind farmers’ houses and connected with their cattle sheds was another way to keep the digesters warm in winter time. biogas production materials were changed to cattle dung. crop residues were first fed to cattle and cattle dung was used as substrate for biogas production. . . . biogas cooking stoves and illuminating lights biogas cooking stoves have been noted as the key role to efficiently utilize biomass energy. the programs have been undertaken in china and india for almost years [ , ]. the traditional cooking stoves in rural china are usually mud-built cylinder with boilers being set on and used to burn biomass energies (crop residues, firewood, animal dung, etc). the energy efficiency of those type stoves for biomass fuels is between % and %, emitting smoke, including the risk of firing, creating health hazard in kitchen [ ]. improved household biogas stoves are produced on the base of natural gas stoves by some gas-fired companies of china (fig. ). new stoves have biogas purifying systems and automatic fire systems that are convenient and safe. biogas lamps (fig. ), which illuminate by burning biogas, are also used in cattle sheds, corridors, storages, and other places in the villager’s houses. the objective of this study is to investigate how to efficiently utilize abundant biomass energy in rural china, improving the rural environment and the villagers’ incomes by high-efficiency [(fig._ )td$fig] fig. . improved biogas stove used in villagers’ kitchen. biomass energy utilization, contributing to an alleviation of energy crisis and global warming. . materials and methods . . natural and socio-economic backgrounds of study area jiangjiazhuang, which is located in eastern shandong of china, is a typical agronomy village in agricultural areas of china (fig. ). it holds households, total population is , total arable land hm and croplands . hm . about . tons fresh crop residues (mainly wheat and corn stalks) are produced each year. farmers conventionally use parts of the crop residues as their livelihood energy, such as cooking, water heating, etc. in , only two cattle were fed and three biogas digesters were built in this village. the rest of the parts of the crop residues were discarded or directly combusted in the field because of no proper ways for consuming them. the situation became more serious in the recent years, large parts of crop residues were discarded or directly combusted in the field because of more and more fossil energies (coal, natural gas, electricity, etc.) had been devoted in peoples’ life[(fig._ )td$fig] fig. . location of study area—jiangjiazhuang. [(fig._ )td$fig] fig. . experimental route was designed in this study. y.h. zheng et al. / renewable and sustainable energy reviews ( ) – with the improvement of living standard. moreover, energy- hungry appliances such as air-conditioners, refrigerators and microwave ovens had gradually entered their homes. if this situation continues, the total energy and fossil energy consump- tion will boost in the near future and aggravate the energy crisis and global warming. . . ‘‘bread’’ forage processing ‘‘bread’’ forage is in fact made by crop residues following a micro-deposited fresh crop residues (mdfcr) technology. the name of ‘‘bread’’ forage comes from its shape like bread, and high nutrition contents and digestion efficiency. the technique of processing ‘‘bread’’ forages is pretty simple: crop residues are immediately reaped after the crop grains being harvested at crop mature stage. the crushed and kneaded crop residues were pressed and framed in cylinder shape with cm diameter and cm height. then cylinders were wrapped with plastic and stored in open air for natural fermentation (fig. ). the relative water content of the ‘‘bread’’ forages is around %. after at least days, the fermented crop residues can be used to feed the cattle. ‘‘bread’’ forages have a special smell (faint scent smell), and the cattle like to eat them. according to feng et al. (co-author, unpublished data), the cattle fed with ‘‘bread’’ forages grew faster than with traditionally processed crop residues. . . experimental design the biomass energy utilization experiment was designed on the objective of wisely reusing biomass energy (crop residues) to inhibit the increment of fossil energies consumption and reduce greenhouse gas emission in rural areas. crop residues were processed into ‘‘bread’’ forage to feed cattle. cattle dung was filled in biogas digesters and the produced biogas for meeting the villagers’ livelihood energy demand. residues produced from biogas digesters were used as green fertilizers to enrich soils. the route of the project was designed as: crops ! crop residues ! ‘‘- ‘‘bread’’ forage ! cattle ! cattle dung ! biogas diges- ter ! biogas/digester residues ! green fertilizers ! crops (fig. ). . . data collection and recalculation data of total crop grain yields, cattle capita and biogas digesters were collected from the statistic data of the local government. crop residues were recalculated on the base of original crop grain yields data. the crop yields were transformed into crop residue values and recalculated, with the mean universal values being gained. the [(fig._ )td$fig] fig. . ‘‘bread’’ forages were processed with crop residues through micro-deposited fresh crop residues (mdfcr) technology. quantities of crop residue utilization were calculated following the methods described by zeng et al. [ ]. the unit of the energy was showed in forms of standard coal basing on the authoritative transform coefficients. the data of energy consumption, crop residues distribution, investments of cattle and biogas digesters and fertilizers were collected by filling in questionnaires on behalf of each household. the microsoft excel and sigma plot (ver. . , spss, chicago, il, usa) were used in data calculation and figure drawing. . . nutrient parameters analysis the nitrogen content (n) was determined following the kjeldahl nitrogen determination method (aacc approved method - [ ]). the crude protein content (pc) was calculated by using the formula: pc (mg g� dm) = n � . crude fat and crude fiber contents were measured according to the method described by zhao et al. [ ]. . . biogas production and energies transforming biogas digesters were filled with cattle dung and pachyrhizus bine ( : ) in . cattle urine and water were simultaneously added into biogas digesters. the biogas digesters were closed and materials were fermented for about d, while the produced amount of biogas might be enough for villagers’ livelihood energy. biogas production was recorded by a biogas hydrometry meter (zg- , kaitai instrument co. ltd., zhejiang, china), which was installed in each household. different species energies (biogas, natural gas, etc.) transforming to standard coal were based on the coefficients showed in table . . . economic benefit economic benefits were calculated according to the temporal market prices of energies, cattle and fertilizers. the benefits were transformed into us$ following the current exchange rate of rmb ( us$ = . rmb). cattle benefit (us$) = cattle weight � market prices � cost. energy saving (us$) = biogas cubage � . � cost. fertilizer saving (us$) = weight of reduced chemical fertili- zers � market prices. crop yield benefit (us$) = increased grain yield � market prices. table coefficients of raw materials and standard coal. species kj/m kc/m kg standard coal/m natural gas , . cattle dung , . soybean/cotton stalk , . wheat stalk , . maize stalk , . biogas . electricity . raw coal . y.h. zheng et al. / renewable and sustainable energy reviews ( ) – . . statistical analysis nutrient components, water contents and digestion rates of differently processed crop residues were separately analyzed in the lab of shandong agricultural university. there were three replicates for each treatment. data were analyzed using a one-way analysis of variance (anova) of spss package (ver. , spss, chicago, il, usa). differences between different types of crop residues were considered to be significant at p � . . . results and discussion . . crop residues distribution and livestock development crop residues produced each year in jiangjiazhuang were around tons during – (fig. ). cattle capita increased [(fig._ )td$fig] fig. . total crop residues yield, cattle capita, proportions of crop residues for livelihood energy/total crop residues (tcr) and crop residues for forage/tcr in jiangjiazhuang from to . from in to in . proportion of crop residues for livelihood energy/total crop residues significantly decreased, while the proportion of crop residues for forage/total crop residues considerably elevated during – . for crop residues distribution (fig. ), in , . % were used as livelihood energy, . % were directly combusted, . % were discarded and only . % crop residues were used as forage. in contrast, in , the proportion of crop residues for forage/total crop residues increased to . %, the proportion of livelihood energy/total crop residues decreased to . %, . % were directly combusted in the field and . % were discarded. traditionally, villagers treated parts of crop residues as livelihood energy and small percentage was used as animal forage, however, large parts of the crop residues were discarded or directly combusted in the field because there were no proper way of consuming the redundant crop residues [ , , , ]. the reason might be most of the villagers could not afford to buy a cattle depending on themselves. in addition, it was hard for the farmers to loan money from the government. although they loaned some money, they did not want to stick their chin out on feeding cattle due to a lack of technologies, such as feeding techniques or medical treatment. as the project was running, the scientists persuaded the local government to loan some money to the farmers being able to buy cattles. and we trained a couple of animal doctors being able to offer services to cure cattle illnesses. the farmers gradually found that feeding cattle by crop residues really could generate benefits. they begun to like this business and the cattle capita in this village were up to in . consequently, we concluded that the key roles to develop livestock in rural areas are: ( ) train technicians for the farmers on feeding cattle; ( ) financial supports from the chinese government is urgently needed. . . ‘‘bread’’ forage nutrition as shown in table , no significant differences were noted between ‘‘bread’’ forage and fresh maize stalks in water content, crude protein/fat/fiber content. the ph value was considerably lower but the digestion rate was drastically higher in ‘‘bread’’ forage than in fresh maize stalks. water content, crude protein/fat/ fiber content and digestion rate were significantly higher in both ‘‘bread’’ forage and fresh maize stalks than dry maize stalks. while the ph value of ‘‘bread’’ forage and fresh maize stalks was lower (< ) than that of dry maize stalks (> ). this is in agreement with wang [ ], which reported acidic forage was easier for animal digestion. therefore, micro-deposited fresh crop residues (mdfcr) technology (‘‘bread’’ forage processing technology) is a crucial tache in improving the livestock development in rural areas of china. . . biogas production biogas production was initiated three decades ago in china [ ]. however, the amount of biogas was low for the reasons of improperly built biogas digesters and a lack of fermentation technologies. as a result, the biogas projects were moved very slowly in the past decades [ , , ]. however, the total energy consumption in this village increased rapidly from to (fig. ). the total amount of biogas digesters were significantly increased during the experiment runs. only two biogas digesters existed in this village and biogas yield was merely m in . many families disliked to build biogas digesters because of ( ) the capital costs; ( ) the biogas yield was too low. along with the experiment run, biogas digesters building technologies were improved and the substrate was changed to cattle dung. as a result the biogas yield considerably increased. the proportions of biogas [(fig._ )td$fig] fig. . proportions of crop residues for different usage in jiangjiazhuang in and , respectively. table nutrient analysis on different treatments of corn stalks. data are the mean�se (n = ). different letters within a column indicate significant differences (p < . , t test). treatment water content (%) ph value nutrition (%) digestion rate (%) protein fate fibrin dry maize stalks � . b . � . a . � . c . � . b . � . a � . c fresh maize stalks � . a . � . b . � . b . � . a . � . b � . b ‘‘bread’’ forage � . a . � . c . � . a . � . a . � . b � . a [(fig._ )td$fig] fig. . total energy consumption, biogas digesters, proportions of coal energy/total energy and biogas energy/total energy in jiangjiazhuang during – . y.h. zheng et al. / renewable and sustainable energy reviews ( ) – energy/total livelihood energy were drastically increased during the experiment run. in contrast, the proportion of coal energy/total livelihood energy significantly decreased during – . more biogas was consumed in the villagers’ daily life, more fossil energies were saved and less greenhouse gases emitted to the atmosphere. in , biogas yield was up to , m relative to . tons standard coal. cattle dung, which comes from cattle body via digestion, was used as the material for generating biogas. it had a lot anaerobic bacterium and high efficiency in producing biogas. the saved standard coals by biogas utilization could produce about . tons co emission (about . tons co emission per ton standard coal combustion). as a result, about . tons co were reduced. so it is conceivable to believe that biogas utilization in rural areas might be one of the key measures to alleviate energy crisis and global warming. . . green fertilizer production along with the industrial development, more and more young farmers immigrate into cities to obtain higher incomes [ ]. their croplands were left to their parents or other persons who did not have opportunities to immigrate to the cities (older men or women). for a reason of saving manpower, less and less animal manures were produced and used while more and more chemical fertilizers were supplied in the croplands. as a result, the soil organic carbon content significantly decreased and the soil physical and chemical characters declined. the crops grain yields were also considerably decreased year after year because of the decline of soil quality. after this project running, the residues in biogas digesters were used as green fertilizers returning to the croplands. on the other hand, huge amount of green fertilizers application could make the soil color change to ‘‘black’’, and it might indicate that plenty of organic carbons were fixed in soil [ , ]. soil carbon sequestration would contribute to reduce atmospheric carbon content. it should be a huge contribution in alleviating global warming. table variation of economic benefit after years experiment in jiangjiazhuang. unit: us$. years cattle benefit energy saving fertilizer saving crop yield benefit total net benefit . . . . . . . . . . y.h. zheng et al. / renewable and sustainable energy reviews ( ) – . . economic benefit and future perspectives livestock and biogas developments in rural areas of china apparently enhanced the farmers’ incomes and reduced their costs in buying energies and fertilizers (table ). total net benefit in was about folds of the one in . wisely biomass energy utilization in rural areas may considerably elevate villagers’ incomes and their life qualities. livestock development in this eco-agricultural circulation enhanced the biomass energy use efficiency. and it was a promising way to change the crop residues into human high nutritional food by turning biomass into animal meat. it would apparently contribute to solving the food security in china. biogas production and utilization in rural areas also significantly alleviated the energy competition between rural and urban areas. it would be a key role to lessen the energy crisis and greenhouse gas emission. jiangjiazhuang is just one of the . million agro-villages in china [ ]. if the biogas project could demonstrate in all those villages in the future, it would be surprising figures in saving fossil energies and reducing greenhouse gases emission. according to the results of the present study in jiangjiazhuang (about saving . tons standard coal and reducing . tons co in ), . million agro-villages will save some . million standard coal and reduce . million tons co emission. on the other hand, long-term increasing green fertilizers application and decreasing chemical fertilizers supply might elevated the soil carbon content [ ]. soil carbon sequestra- tion is another crucial measurement to reduce the atmospheric carbon concentration [ , ]. a study on soil carbon sequestration should be exposed in the future. in a word, livestock and biogas development in agricultural areas of china have been proved a promising project in improving human life quality. however, it is not so easy to demonstrate this project because the farmers are lack of money and technologies. therefore, in order to make the project going smoothly in the future, financial and technological supports will be needed from the chinese government. . conclusions the results of the present study indicated that proper utilization of biomass energy in rural areas of china through developing livestock and biogas production might effectively improve the biomass use efficiency and reduce fossil energy consumption. biomass energy utilization in rural areas might be a great contribution to alleviate the energy crisis and global warming. acknowledgements financial supports by the eco-village establishment project of the german embassy, the th national five-year plan on scientific and technological support projects ( badb b ) and the national scientific and technological support projects ( bad b ) are gratefully acknowledged. references [ ] aacc. approved methods of american association of cereal chemists. st. 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[ ] zhao sj, li dq, zhang yh. plant physiology experimental method. china agriculture press; . 	biomass energy utilization in rural areas may contribute to alleviating energy crisis and global warming: a case study in a typical agro-village of shandong, china 	introduction 	energy status in rural china 	energy policy of the chinese government 	biomass resource in rural china 	livestock development 	biogas production and utilization 	improved biogas digester and biogas production 	biogas cooking stoves and illuminating lights 	materials and methods 	natural and socio-economic backgrounds of study area 	‘‘bread’’ forage processing 	experimental design 	data collection and recalculation 	nutrient parameters analysis 	biogas production and energies transforming 	economic benefit 	statistical analysis 	results and discussion 	crop residues distribution and livestock development 	‘‘bread’’ forage nutrition 	biogas production 	green fertilizer production 	economic benefit and future perspectives 	conclusions 	acknowledgements 	references a metal nitride interlayer for long life lithium sulfur batteries journal of energy chemistry ( ) – contents lists available at sciencedirect journal of energy chemistry journal homepage: www.elsevier.com/locate/jechem a metal nitride interlayer for long life lithium sulfur batteries jin-lei qin a , b , huiyou zhao a , jia-qi huang b , c , ∗ a department of materials science and engineering, china university of mining and technology (beijing), beijing , china b advanced research institute of multidisciplinary science, beijing institute of technology, beijing , china c cas key laboratory of carbon materials, institute of coal chemistry, chinese academy of sciences, taiyuan , shanxi, china a r t i c l e i n f o article history: received june accepted july available online july keywords: shuttle of polysulfides interlayers layered double hydroxides composite separators lithium sulfur batteries g l h c ( n t s a s a l h a [ d a b t e fig. . sem images of nanoparticle-stacked co n and ni n prepared by nh an- nealing of ldhs on carbon paper [ ] . e s e i t w n n h with the growing concerns on global energy crisis and the reenhouse effect, the exploration on renewable energy and re- ated emerging energy conversion and storage technologies are ighly interested [ ] . lithium sulfur (li–s) battery system re- eives great attention for its high theoretical specific energy wh/kg), which is deemed to be a promising candidate as ext generation high energy density batteries [ ] . yet, the prac- ical application of the li–s batteries is limited by the notorious huttle effect of lithium polysulfides (lipss) between cathode and node [ , ] . among diverse strategies that devoted to suppress the huttle effect, a functional interlayer between the cathode and sep- rator has been proposed to sterically obstruct and chemically bind ipss, kinetically favoring lipss interconversion [ – ] . for instance, e et al. employed an ultrathin interlayer composed of li ti o nd carbon nanofiber to effectively retard shuttle of polysulfides ] . simultaneously, the functional interlayer formed by the re- uced graphene oxide and activated carbon is proposed by zhang nd coworkers can capture and reuse polysulfide species in li–s atteries [ ] . recently, wang and co-workers from hunan university for he first time demonstrated the metal nitrides derived from lay- ∗ corresponding author at: advanced research institute of multidisciplinary sci- nce, beijing institute of technology, beijing , china. e-mail address: jqhuang@bit.edu.cn (j.-q. huang). t p o t r ttps://doi.org/ . /j.jechem. . . - /© science press and dalian institute of chemical physics, chinese academ red double hydroxides (ldhs) as a self-supporting interlayer in- erted independently between sulfur cathode and pp separator, ndowing the cell with long cycling life, excellent cycle stabil- ty, and high coulombic efficiency retention in working li–s bat- eries [ ] . nanoparticle-stacked nitride material (co n and ni n) as prepared by annealing ldhs on carbon paper (cp) under h atmosphere at °c (named as n-ldh- /cp). the formed -ldh- /cp functional interlayer possesses the following attrac- ive attributes: ( ) large specific surface area to effectively absorb olysulfides; ( ) hydrophilic metal-o groups to anchor polysulfides n the polar surface; ( ) good electric conductivity to re-utilize he polysulfides anchored on the interlayer; ( ) the structure to etain electrolyte for excellent electrochemical performance. y of sciences. published by elsevier b.v. and science press. all rights reserved. https://doi.org/ . /j.jechem. . . http://www.sciencedirect.com http://www.elsevier.com/locate/jechem mailto:jqhuang@bit.edu.cn https://doi.org/ . /j.jechem. . . j.-l. qin et al. / journal of energy chemistry ( ) – fig. . (a) schematic diagram of the li-s battery with n-ldh- /cp interlayer; (b) long cycle performance of a li-s battery with n-ldh- /cp interlayer [ ] . a v t r [ specifically, the surface of transition metal nitrides on cp formed an oxide passivation layer with exposing abundant active sites and adsorption sites, which exhibited excellent chemical stability and hindered the diffusion of polysulfides by chemical and physical ad- sorption. additionally, co n and ni n nanoparticles retain large enough inter-particle space to store electrolyte ( fig. ). accord- ingly, the n-ldh- /cp interlayer between the rgo-s cathode and pp (celgard ) ( fig. a) exhibited stable cycle performance. as demonstrated in fig. (b), the discharge capacity was . mah g − at the first cycle and maintained . % after cycles. the metal nitrides derived from ldhs with above advan- tages significantly improved both capacity and cycling stability of li–s cells, demonstrating the importance of the rational design of cell configuration and interfacial properties. furthermore, the em- ployed co n/ni n/cp interlayer derived from ldh is highly inspir- ing, which may arouse great interest in exploring emerging func- tional interlayers by accurately regulating active sites for advanced energy storage devices. cknowledgments this work was supported by the national key research and de- elopment program (no. yfa ) and cas key labora- ory of carbon materials (no. klcmkfjj ). eference [ ] x. zhang , x. cheng , q. zhang , j. energy chem. ( ) – . [ ] j.-q. huang , p.-y. zhai , h.-j. peng , w.-c. zhu , q. zhang , sci. bull. ( ) – . [ ] l.y. li , c.g. chen , a.s. yu , sci. china chem. ( ) – . 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( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref http://refhub.elsevier.com/s - ( ) -x/sbref 	a metal nitride interlayer for long life lithium sulfur batteries 	 acknowledgments 	 reference synergy between auranofin and celecoxib against colon cancer in vitro and in vivo through a novel redox-mediated mechanism cancers article synergy between auranofin and celecoxib against colon cancer in vitro and in vivo through a novel redox-mediated mechanism yi han , , ,† , ping chen , , ,†, yanyu zhang , , , wenhua lu , , , wenwen ding , , , yao luo , , , shijun wen , , , , ruihua xu , , , , panpan liu , , , ,* and peng huang , , , ,* department of experimental therapeutics, sun yat-sen university cancer center, guangzhou , china state key laboratory of oncology in south china, guangzhou , china collaborative innovation center for cancer medicine, guangzhou , china school of pharmaceutical sciences, sun yat-sen university, wai huan east road, guangzhou , china department of medical oncology, sun yat-sen university cancer center, guangzhou , china metabolic innovation cancer, sun yat-sen university, guangzhou , china * correspondence: liupp@sysucc.org.cn (p.l.); huangpeng@sysucc.org.cn (p.h.) † these authors contributed equally to this work. received: may ; accepted: june ; published: july ���������� ������� abstract: recent study suggests that auranofin (af), a us food and drug administration (fda)-approved drug for treatment of rheumatoid arthritis, has selective anticancer activity in various experimental models. its clinical applications in cancer treatment, however, have been hampered due in part to its relatively moderate activity as a single agent. in this study, we performed a high-throughput screening of the fda-approved drug library for clinical compounds that potentiate the anticancer activity auranofin, and unexpectedly identified an anti-inflammatory drug celecoxib (ce) that potently enhanced the therapeutic activity of af in vitro and in vivo. mechanistically, af/ce combination induced severe oxidative stress that caused ros-mediated inhibition of hexokinase (hk) and a disturbance of mitochondrial redox homeostasis, resulting in a significant decrease of atp generation. the ce-induced ros increase together with af-medicated inhibition of thioredoxin reductase cause a shift of trx to an oxidized state, leading to degradation of mtco and dysfunction of the electron transport chain. our study has identified a novel drug combination that effectively eliminates cancer cells in vivo. since af and ce are fda-approved drugs that are currently used in the clinic, it is feasible to translate the findings of this study into clinical applications for cancer treatment. keywords: colorectal cancer; drug repurposing; drug combination; auranofin; celecoxib . introduction colorectal cancer (crc) is the third most common cancer type and the second leading cause of cancer-related mortality worldwide, with about million individuals being diagnosed and more than , dying from the disease, annually, all over the world [ , ]. despite significant advances in early detection and treatment, the long-term overall survival rates of crc patients have not been significantly improved during the past decades [ ]. chemotherapy is an important treatment approach for patients with crc. however, crc patients who progress after receiving two lines of chemotherapy have limited treatment options [ – ]. therefore, there is an unmet need for new drugs that can efficiently eliminate crc cells in vivo. recently, repositioning of the established non-cancer drugs for cancer patients has become an important strategy to develop effective cancer drugs due to relatively lower cancers , , ; doi: . /cancers www.mdpi.com/journal/cancers http://www.mdpi.com/journal/cancers http://www.mdpi.com https://orcid.org/ - - - http://www.mdpi.com/ - / / / ?type=check_update&version= http://dx.doi.org/ . /cancers http://www.mdpi.com/journal/cancers cancers , , of costs and faster drug development, since information on the mechanisms of drug action, formulations, pharmacokinetics, and safety profiles are already available to facilitate their clinical applications [ , ]. auranofin (af) is an oral gold-containing compound approved by the us food and drug administration (fda) for the treatment of rheumatoid arthritis. af is known to inhibit thioredoxin reductase (trxr) and exhibits preferential anticancer activity [ , ]. our previous study showed that af was able to preferentially killed leukemia cells in vitro and reduced leukemia burden in vivo [ ]. we also demonstrated that af could eliminate cancer stem-like side population cells through inducing ros accumulation and inhibition of glycolysis in lung cancer model [ ]. the promising anticancer activity of af observed in various experimental cancer models has led to clinical evaluation of this drug for cancer treatment. currently, af is in clinical trials for several cancer types, including leukemia, lung cancer and ovarian cancer (https://clinicaltrials.gov/ct /show/nct , nct , nct ). however, the clinical outcomes reported from some of the clinical trials are unsatisfactory due to only moderate and transient therapeutic activity [ ]. thus, it is important to develop new strategies that could enhance the therapeutic activity of af in vivo. proper drug combination is an effective strategy to improve anticancer activity, since the use of multiple drugs provides an effective mean to target multiple cellular abnormalities with a potential to achieve synergistic therapeutic effect, to overcome drug resistance, and to possibly reduce toxic side effects due to dosage reduction for each individual drug in the combination [ , ]. with clinical applications in mind, we used a library of fda-approved drugs ( drugs in total) in a cell-based high-throughput screening (hts) assay to identify clinical compounds that could potentiate the therapeutic activity of af in vitro and in vivo, and investigate the underlying mechanisms. . results . . high-throughput screening for drugs that synergize with auranofin against cancer cells in vitro previous studies have shown that the anti-rheumatoid drug auranofin (af) possesses anticancer activity in various types of cancer cells. however, its clinical application in cancer treatment has been hampered due to unsatisfactory in vivo therapeutic activity. to identify clinical drugs that can potentiate the therapeutic effect of af, a cell-based high-throughput assay was performed to screen a drug library of fda-approved clinical compounds. as shown in figure , we first exposed dld- cells (colon cancer) to various concentration of af to establish a dose-dependent inhibition curve (figure a) to select a subtoxic concentration ( µm) of af, which alone did not cause significant cytotoxicity. we then incubated dld- cells with the fda drug library in duplicate and with each drug (designated as compound x in figure b) at a concentration of µm). to one set of the duplicate drug panels, af ( µm) was added to each well to test the combined effect of af and compound x. for the second set of the samples, dld- cells were incubated with each compound without af to evaluate the impact of compound x alone. after h, cell growth inhibition was measured by mts assay. the combined drug (af + x) effect on cell growth was subtracted by the respective x effect to calculate the net potentiation (figure b). any compound that caused a net increase of > % in cell growth inhibition was considered as a hit, as illustrated in figure c. using this criterion, compounds were identified as potential hits. these lead compounds were then selected for further test using multiple concentrations ( . – µm) to evaluate their potential synergistic effect with af. drug combination indexes (ci values) were calculated using the calcusyn software. these processes of selection and validation, led to the identification of celecoxib, an inhibitor of cox- , that consistently potentiated the anticancer activity of af. https://clinicaltrials.gov/ct /show/nct cancers , , of cancers , , x of figure . high-throughput screening of drugs that enhance the anticancer efficiency of auranofin (af). (a) dose–response curves of auranofin treatment for h for dld- cells using mts assay. (b) scheme showing high-throughput screening for fda-approved compounds that enhance the anticancer efficiency of auranofin in dld- cells. (c) in this screening, μm af and μm drug x were used. the inhibition ratio of cell growth increased at least % between combination therapy and drug x was considered as a potential target. high-throughput screening (hts) data of drugs combined with af using dld- cells; the red line indicates the threshold (> inhibition elevated); the red arrow and dot indicate the final candidate, celecoxib. data are presented as the mean ± standard deviation (sd) of a triple assay. . . auranofin and celecoxib synergistically induce colorectal cancer cell death in vitro since celecoxib (ce) is known to have cancer prevention activity and the plasma drug concentrations could be achieved at μm range, we decided to further test whether the apparent synergistic effect of ce in combination with af observed in dld- could be a general phenomenon in colon cancer, we included two additional colorectal cancer cell lines, hct and ht- , in the quantitative evaluation of multiple concentrations of ce in combination with af. as shown in figure , combination of ce and af resulted in a dose-dependent enhancement of inhibition of cell growth in all three colorectal cancer lines (figure a). notably, the combination index values between ce and af in these three cell lines are all less than (figure b), indicating a strong synergy between the two drugs. figure . high-throughput screening of drugs that enhance the anticancer efficiency of auranofin (af). (a) dose–response curves of auranofin treatment for h for dld- cells using mts assay. (b) scheme showing high-throughput screening for fda-approved compounds that enhance the anticancer efficiency of auranofin in dld- cells. (c) in this screening, µm af and µm drug x were used. the inhibition ratio of cell growth increased at least % between combination therapy and drug x was considered as a potential target. high-throughput screening (hts) data of drugs combined with af using dld- cells; the red line indicates the threshold (> inhibition elevated); the red arrow and dot indicate the final candidate, celecoxib. data are presented as the mean ± standard deviation (sd) of a triple assay. . . auranofin and celecoxib synergistically induce colorectal cancer cell death in vitro since celecoxib (ce) is known to have cancer prevention activity and the plasma drug concentrations could be achieved at µm range, we decided to further test whether the apparent synergistic effect of ce in combination with af observed in dld- could be a general phenomenon in colon cancer, we included two additional colorectal cancer cell lines, hct and ht- , in the quantitative evaluation of multiple concentrations of ce in combination with af. as shown in figure , combination of ce and af resulted in a dose-dependent enhancement of inhibition of cell growth in all three colorectal cancer lines (figure a). notably, the combination index values between ce and af in these three cell lines are all less than (figure b), indicating a strong synergy between the two drugs. cancers , , of cancers , , x of figure . auranofin and celecoxib synergistically induce colorectal cancer cell death in vitro. (a) dose–response curves of celecoxib with or without μm auranofin for the indicated cells. data are presented as the mean ± standard deviation (sd) of a triple assay. cells treated with dmso alone were used as controls, and their values were set as . (b) combination index (ci) of celecoxib and auranofin in the indicated three cell line cells as described in a was analyzed by using calcusyn version . software (biosoft). ci > indicates antagonist effect; ci = indicates additive effect; ci < indicates synergistic effect. (c) apoptosis induced by af ( μm) and combination with celecoxib ( μm) for h was detected by annexin v/pi double-staining followed by flow cytometric analysis in the indicated three cell lines. (d) the colony formation assay of three cancer cell lines treated with indicated conditions of af and ce for weeks. we then used two additional assays to further confirm the synergistic drug combination effect. apoptosis assay was performed to test the acute cytotoxic effect of af and ce. dld- , hct , and ht- cells were treated with af ( μm), ce ( μm), or both for h, followed by double-staining with annexin v/pi and analysis by flow cytometry. as shown in figure c, the cell figure . auranofin and celecoxib synergistically induce colorectal cancer cell death in vitro. (a) dose–response curves of celecoxib with or without µm auranofin for the indicated cells. data are presented as the mean ± standard deviation (sd) of a triple assay. cells treated with dmso alone were used as controls, and their values were set as . (b) combination index (ci) of celecoxib and auranofin in the indicated three cell line cells as described in a was analyzed by using calcusyn version . software (biosoft). ci > indicates antagonist effect; ci = indicates additive effect; ci < indicates synergistic effect. (c) apoptosis induced by af ( µm) and combination with celecoxib ( µm) for h was detected by annexin v/pi double-staining followed by flow cytometric analysis in the indicated three cell lines. (d) the colony formation assay of three cancer cell lines treated with indicated conditions of af and ce for weeks. cancers , , of we then used two additional assays to further confirm the synergistic drug combination effect. apoptosis assay was performed to test the acute cytotoxic effect of af and ce. dld- , hct , and ht- cells were treated with af ( µm), ce ( µm), or both for h, followed by double-staining with annexin v/pi and analysis by flow cytometry. as shown in figure c, the cell survival rates in the af-treated, ce-treated, and (af+ce)-treated dld- cells were . %, . %, and . %, respectively, indicating a more than additive cytotoxic effect. similar synergistic cytotoxicity was also observed in hct and ht- cells (figure c and figure s ). to evaluate the long-term impact of ce and af on cell renewal and proliferation, a colony formation assay was performed. as shown in figure d and figure s , there was a synergy between the two drugs in their inhibition of colony formation in all three cell lines. interestingly, the combination of ce and af exerted only a minimal cytotoxic effect on human normal colon epithelial cells (ccd ) and human normal colon fibroblast cells (ccd ), suggesting a preferential killing of cancer cells by the drug combination (figure s ). . . combination of af and ce induced a severe energy crisis in cancer cells to explore the possible mechanisms by which ce potentiated the anticancer activity of af, we first evaluated the potential role of cox- in affecting the cellular sensitivity. short interfering rna (sirna) was used to specifically knockdown the expression of cox- in dld- cancer cells, and their sensitivity to af and ce was then tested. as shown in figure s , the knockdown of cox- expression by two different sirnas (si- and si- ) did not affect the cellular sensitivity to af, ce, or their combination, suggesting that inhibition of cox- by ce might not play a significant role in enhancing cellular sensitivity to af. this negative result prompted us to explore other mechanisms. based on our previous finding that af could inhibit hk activity and reduce cellular atp at a relatively high concentration ( µm) [ ], we decided to test if af and ce combination could synergistically disrupt energy metabolism in colon cancer cells. since mammalian cells produce atp via oxidative phosphorylation in the mitochondria and glycolysis in the cytosol [ , ], and cancer cells are known to rewire their metabolism to meet energetic and anabolic needs [ , ], we thus used seahorse xfe extracellular flux analyzer to measure oxygen consumption rate (ocr) and extra cellular acidification rate (ecar) as key indicators of oxidative phosphorylation and glycolysis, respectively. as shown in figure a, treatment of dld- cells with µm af alone led to a moderate inhibition of ecar and ocr, whereas µm ce alone did not caused any significant inhibition of ecar or ocr. surprisingly, combination of the same concentrations of af ( µm) and ce ( µm) resulted in a severe inhibition of ecar and ocr. this suppression of energy metabolism led to a severe depletion of cellular atp (figure b). similar patterns of metabolic inhibition and atp depletion were also observed in hct cells (figure c,d) and in ht- cells (figure e,f). importantly, the severe atp depletion was detected before the occurrence of cell death. as shown in figure g and figure s , the vast majority of cells remain intact at h after treatment with af + ce, while cellular atp was depleted by more than % at this time point in all three cell lines (figure b,d,f). these results together suggest that induction of energy crisis by the drug combination is the approximal event that occurred before cell death. cancers , , of cancers , , x of figure . af/ce combination induced severe energy crisis. (a,c,e) real-time measurement of ecar and ocr in indicated conditions using the seahorse bioscience extra cellular flux analyzer. for the glycolysis analysis (left panel), cells were sequentially treated with vehicle or drugs (af μm, ce μm, and af μm + ce μm), glucose ( mm), oligomycin (o, μm), -dg ( μm). for the mitochondrial function analysis (left panel), cells were sequentially treated with vehicle or drugs (af μm, ce μm, and af μm + ce μm), oligomycin (o, μm), fccp (f, μm) and rotenone/antimycin a (r/a, . μm). (b,d,f) quantitative bar graph of intracellular atp from three separate experiments after cells treated with af ( μm), ce ( μm) and their combination (af + ce) for h. percent atp was calculated relative to untreated cells (set to %). each bar represents mean ± sd, n = separate experiments; ** p < . (g) dld- , hct and ht- cells were treated with af ( μm), ce ( μm) and their combination for h. cytotoxicity was determined by annexin v/pi assay. figure . af/ce combination induced severe energy crisis. (a,c,e) real-time measurement of ecar and ocr in indicated conditions using the seahorse bioscience extra cellular flux analyzer. for the glycolysis analysis (left panel), cells were sequentially treated with vehicle or drugs (af µm, ce µm, and af µm + ce µm), glucose ( mm), oligomycin (o, µm), -dg ( µm). for the mitochondrial function analysis (left panel), cells were sequentially treated with vehicle or drugs (af µm, ce µm, and af µm + ce µm), oligomycin (o, µm), fccp (f, µm) and rotenone/antimycin a (r/a, . µm). (b,d,f) quantitative bar graph of intracellular atp from three separate experiments after cells treated with af ( µm), ce ( µm) and their combination (af + ce) for h. percent atp was calculated relative to untreated cells (set to %). each bar represents mean ± sd, n = separate experiments; ** p < . (g) dld- , hct and ht- cells were treated with af ( µm), ce ( µm) and their combination for h. cytotoxicity was determined by annexin v/pi assay. cancers , , of . . combination of ce and af caused inhibition of hexokinase enzyme activity based on our previous observation that af could inhibit hexokinase (hk) enzyme activity [ ], we tested if the combination of af and ce could lead to more inhibition of hk as a possible explanation for the observed potent inhibition of glycolysis by the drug combination. colon cancer cell lines were incubated with af ( µm), ce ( µm), or their combination for h, and cellular protein extracts were used for analysis of hexokinase activity. as shown in figure , the relatively low concentrations of af ( µm) or ce ( µm) alone caused only slight/modest inhibition of hk enzyme activity, and their combination potently inhibited hk activity in all three cell lines tested (figure a,c,e). the inhibition of hk was associated with a decrease in glucose uptake and lactate production (figure b,d,f). these results suggested that af/ce combination suppressed glycolysis via inhibition of hexokinase enzyme activity, possibly due to ros-mediated damage to hk protein (see below). cancers , , x of . . combination of ce and af caused inhibition of hexokinase enzyme activity based on our previous observation that af could inhibit hexokinase (hk) enzyme activity [ ], we tested if the combination of af and ce could lead to more inhibition of hk as a possible explanation for the observed potent inhibition of glycolysis by the drug combination. colon cancer cell lines were incubated with af ( μm), ce ( μm), or their combination for h, and cellular protein extracts were used for analysis of hexokinase activity. as shown in figure , the relatively low concentrations of af ( μm) or ce ( μm) alone caused only slight/modest inhibition of hk enzyme activity, and their combination potently inhibited hk activity in all three cell lines tested (figure a,c,e). the inhibition of hk was associated with a decrease in glucose uptake and lactate production (figure b,d,f). these results suggested that af/ce combination suppressed glycolysis via inhibition of hexokinase enzyme activity, possibly due to ros-mediated damage to hk protein (see below). figure . af/ce combination suppressed glycolysis through hexokinase (hk) inhibition. (a,c,e) curves of hexokinase activity in cells treated with indicated conditions. cells were incubated with af μm, ce μm, and af μm + ce μm for h, and protein extracts were used to analysis of hexokinase activity. (b,d,f) inhibition of glucose uptake and lactate production by af μm, ce μm, and af μm + ce μm in indicated cells. three cell lines were treated with the indicated conditions of af and ce in fresh medium for h. the culture media from each sample was then collected for analysis of glucose and lactate. each bar represents mean ± sd of three separate measurements, ** p < . . figure . af/ce combination suppressed glycolysis through hexokinase (hk) inhibition. (a,c,e) curves of hexokinase activity in cells treated with indicated conditions. cells were incubated with af µm, ce µm, and af µm + ce µm for h, and protein extracts were used to analysis of hexokinase activity. (b,d,f) inhibition of glucose uptake and lactate production by af µm, ce µm, and af µm + ce µm in indicated cells. three cell lines were treated with the indicated conditions of af and ce in fresh medium for h. the culture media from each sample was then collected for analysis of glucose and lactate. each bar represents mean ± sd of three separate measurements, ** p < . . cancers , , of . . af and ce combination induced severe ros stress leading to protein oxidation and dysfunction of mitochondrial electron transport chain we next investigated how the combination of af and ce affected mitochondrial oxidative phosphorylation. it is known that mitochondrial proteins could be affected by redox status [ , ]. it is also known that af could inhibit thioredoxin reductase (trxr) and thus affect the conversion of oxidized thioredoxins (trx) to the reduced form which, in turn, impact the redox states of other proteins [ , ]. thus, we first examined the redox status of mitochondrial thioredoxin (trx ) after drug treatment, using “redox western blotting” to distinguish the oxidized trx from its reduced form as illustrated in figure a. the results showed that under the normal cell culture conditions (without drug treatment), trx was mainly kept in the reduced state trx (figure b, upper band). addition of exogenous h o caused an oxidation of trx , which appeared as the lower band. importantly, treatment of cells with a combination of af and ce led to an almost complete oxidation of trx in all three cell lines (dld- , hct , ht- ), whereas either drug alone was insufficient to induce a major shift of trx redox status (figure b). consistently, analysis of cellular ros showed that af or ce alone caused relatively moderate increase of cellular ros, whereas the combination af and ce induced a marked increase of ros accumulation (figure c, in log-scale and figure s ). the mitochondrial tca cycle and the electron transport chain are two main components that determine the mitochondrial energy metabolism. since mitochondrial aconitate hydratase (aco ) is an tca enzyme containing iron–sulfur clusters known to be sensitive to ros stress [ ], we first test the impact of af and ce on this molecule. unexpectedly, all drug treatment conditions including af + ce combination did not cause any significant change in aco protein (figure d). we then evaluated the impact of af and ce on explore the electron transport chain (etc) components. there are five complexes (i–v) in the etc system, and each complex contains various protein subunits. we thus assessed the impact of af and ce treatment on the five commonly used protein components (ci-ndufb , cii-sdhb, ciii-uqcrc , civ-mtco and cv-atp a) of the five etc complexes. interestingly, the mitochondrially encoded cytochrome c oxidase ii (mtco , a protein component of complex iv) decreased significantly in the af+ce combination group (figure e and figure s ), whereas af or ce alone did not induce such change. the selective decrease in mtco was observed in all three cell lines tested (figure e). there was no significant change in other respiratory complexes (figure s ). analysis of mrna expression by rt-pcr showed that there was no significant changes in the mtco mrna level (figure f), suggesting that the change in mtco protein was likely due to alteration in the protein stability. since it has been reported that akt is often activated via phosphorylation as a compensatory mechanism in response to mitochondrial dysfunction [ , ], we then examined the akt phosphorylation status at s when cells were treated with af, ce, or their combination. surprisingly, akt phosphorylation at s decreased significantly in cells treated with af/ce combination (figure e), indicating that the akt compensatory mechanism in response to mitochondrial inhibition in cancer cells was somehow disabled by the drug combination. cancers , , of cancers , , x of figure . af/ce combination disturbed redox homeostasis which resulted in disordered electron transport chain. (a) principle of trx redox western blot assays. dld- , hct , and ht- cells were treated with indicated conditions for h. treatment with mm h o for min was used as a positive control (pc). (b) trx redox state was evaluated by redox immunoblot. (c) three cell lines were treated with the indicated conditions for h, and cellular ros levels were measured by flow cytometry analysis after the cells were stained with dcf-da. (d,e) dld- , hct and ht- cells were treated with indicated conditions for h, and cell extracts were analyzed by western blot for aco , mtco , p-akt (ser ) and total akt protein. (f) mtco mrna level in three cell lines treated with the indicated conditions. figure . af/ce combination disturbed redox homeostasis which resulted in disordered electron transport chain. (a) principle of trx redox western blot assays. dld- , hct , and ht- cells were treated with indicated conditions for h. treatment with mm h o for min was used as a positive control (pc). (b) trx redox state was evaluated by redox immunoblot. (c) three cell lines were treated with the indicated conditions for h, and cellular ros levels were measured by flow cytometry analysis after the cells were stained with dcf-da. (d,e) dld- , hct and ht- cells were treated with indicated conditions for h, and cell extracts were analyzed by western blot for aco , mtco , p-akt (ser ) and total akt protein. (f) mtco mrna level in three cell lines treated with the indicated conditions. . . auranofin and celecoxib exhibit synergistic therapeutic effect in vivo based on the synergistic effect of af and ce in vitro, we further evaluated the potential therapeutic activity of af and ce in vivo, using mice bearing dld- colon cancer xenografts as a tumor model. six groups of mice were treated as follows: ( ) solvent control (olive oil); ( ) af mg/kg; ( ) ce mg/kg; ( ) ce mg/kg; ( ) af mg/kg + ce mg/kg; ( ) af mg/kg + ce mg/kg. all treatments were given via oral administration (p.o.). this treatment protocol was well-tolerated, and the mice appeared normal, physically active, and without significant weight loss (figure a). the mice in group exhibited some moderate decrease in body weights during the first – weeks of treatment, and eventually regained the body weights. as shown in figure b–d, each drug as a cancers , , of single agent exhibited moderate therapeutic activity, whereas the combination of af and ce produced significantly better therapeutic outcome. at the end of the experiment, the mean tumor weight in group was . g, significantly less than that of . g in the vehicle-treated control group (p < . ); the mean tumor weight in af-treated and ce ( mg/kg)-treated groups were . g and . g, respectively. the mean tumor weight in group was . g, significantly less than that of vehicle-treated control group (p < . ). it is interesting to note that ce at the dosage of mg/kg also showed significant therapeutic activity and reduced the tumor weights to . g (p = . ). when the protein extracts of the tumor tissues were analyzed by western blotting, we observed a decrease in mtco level in the drug-treated group, with the drug combination groups showing the most significant reduction of mtco protein (figure e). these data were consistent with that observed in vitro, suggesting similar mechanisms of drug action in vitro and in vivo. cancers , , x of figure . effect of af/ce combinational treatment in vivo. athymic nude mice bearing dld- xenografts were treated with the following drugs via oral injection (p.o.), with olive oil (vehicle), af mg/kg, ce mg/kg, ce mg/kg, af mg/kg + ce mg/kg (a + c ), af mg/kg + ce mg/kg (a + c ). eight days after inoculation, tumor size and body weight of mice from each group ( mice per group) were measured twice every week. (a) body weight; (b) tumor growth. statistical significance of the differences in mean tumor volume between vehicle and indicated groups were analyzed by t-test, and all tests were two-sided. (c) gross images and comparison of excised tumor size. (d) tumor weights of different treatment groups at the end of animal experiment ( days). ** p < . (e) mtco protein levels in tumors excised from mice treated with the indicated conditions. (f) schematic model explaining the af/ce combinational therapy. ce induced ros increase, which in turn causes oxidation of proteins (trxs, hk and mtco ). af inhibits trxr, and thus keeps trxs in oxidized form, which cannot reduce/repair the oxidized proteins (hk, mtco ) leading to inhibition of both glycolysis and mitorespiration, atp depletion, and cell death. figure . effect of af/ce combinational treatment in vivo. athymic nude mice bearing dld- xenografts were treated with the following drugs via oral injection (p.o.), with olive oil (vehicle), af mg/kg, ce mg/kg, ce mg/kg, af mg/kg + ce mg/kg (a + c ), af mg/kg + ce mg/kg (a + c ). eight days after inoculation, tumor size and body weight of mice from each group ( mice per group) were measured twice every week. (a) body weight; (b) tumor growth. statistical significance of the differences in mean tumor volume between vehicle and indicated groups were analyzed by t-test, and all tests were two-sided. (c) gross images and comparison of excised tumor size. (d) tumor weights of different treatment groups at the end of animal experiment ( days). ** p < . (e) mtco protein levels in tumors excised from mice treated with the indicated conditions. (f) schematic model explaining the af/ce combinational therapy. ce induced ros increase, which in turn causes oxidation of proteins (trxs, hk and mtco ). af inhibits trxr, and thus keeps trxs in oxidized form, which cannot reduce/repair the oxidized proteins (hk, mtco ) leading to inhibition of both glycolysis and mitorespiration, atp depletion, and cell death. cancers , , of . discussion repurposing existing drugs for new therapeutic indications may not only have the advantage of saving time and costs, but also provide opportunities to gain new understanding of the mechanisms of drug action and the biology of diseases. auranofin is an antirheumatic drug that has been used in the clinic for many years. this compound has attracted increasing attention in recent years, and is considered as a potential anticancer drug due to its broad anticancer activity as observed in multiple cancer models [ , , ]. however, its applications to clinical treatment of cancer have been hampered due, in part, to only modest therapeutic activity observed in vivo. for instance, in a clinical trial of af in patients with chronic lymphocytic leukemia (cll), although drug-induced oxidative stress and apoptosis were observed, the clinical responses were transient, with limited therapeutic activity [ ]. thus, it is important to identify agents that could be used in clinic to potentiate the therapeutic activity of auranofin for cancer treatment. to this end, we conducted a high throughput screening of a drug library containing fda-approved clinical drugs and identified celecoxib, that could enhance the anticancer activity of af in vitro and in vivo. the discovery that ce potentiated the anticancer activity of af is somewhat surprising, since ce is a nonsteroidal anti-inflammatory drug (nsaid) that selectively inhibits cyclo-oxygenase- (cox- ). although ce could be considered as potential cancer prevention agent due to its anti-inflammatory property, its ability to enhance the killing of cancer cells was not anticipated nor could be reasonably explained by its key mechanism of action (inhibition of cox- ). indeed, we observed that a specific knockdown of cox- expression did not enhance the sensitivity of colon cancer cells to af, suggesting that cox- unlikely plays a significant role in affecting cellular sensitivity to af (figure s ). our study showed that af and ce synergistically induced an energy crisis, which seemed to be a key event leading to cancer cell death. interestingly, there are reports that rheumatoid arthritis patients treated with celecoxib exhibited lower risk for colorectal cancer [ , ], suggesting potential anticancer activity of this drug. however, the clinical effect of celecoxib in combination with auranofin still remains to be evaluated. suppression of glycolysis through inhibition of hexokinase (hk) and abrogation of mitochondrial oxidative phosphorylation via oxidative damage to respiratory chain seem to be two key mechanisms by which af and ce induce energy crisis in cancer cells. this is supported by the data in figures – . however, the key issue is how af and ce could synergistically inhibit hk and disrupt mitochondrial respiration? based on the data we obtained in the current study, together with the published data by other groups, we proposed that af, through its ability to inhibit thioredoxin reductase, could compromise the cellular ability to reduce oxidized thioredoxins. in the absence of additional oxidative stress, cells could still maintain redox homeostasis by utilizing the available cellular antioxidants. however, in the presence of additional oxidative stress, such as ros production induced by ce, the cancer cells could no longer maintain their redox balance, and oxidative damage to the redox-sensitive proteins would then occur. this might explain why the drug combination could impact both the glycolytic enzyme hk and the mitochondrial respiratory chain component mtco . it is known that the reduced form of thioredoxins play a key role in the repair of oxidized proteins, and the fact that the af + ce combination caused a shift of the mitochondrial trx to oxidized form (figure b) supports the hypothesis that af + ce combination would lead to oxidative damage to mitochondrial redox-sensitive proteins and thus cause dysfunction of the mitochondrial respiratory chain. consistently, previous studies also suggest that aberrant ros levels and a change in redox status could affect protein structure and function. damdimopoulos et al. suggest that trx could interact with certain components of the mitochondrial respiratory chain and might play an important role in the regulation of the mitochondrial membrane potential [ ]. interestingly, this study also showed that overexpression of trx could confer resistance to etoposide, consistent with our finding that oxidation of trx led to increased sensitivity to auranofin. likewise, it is possible that hk protein might also be modified by ros and lost it enzyme activity. due to the high molecular weight of hk, it is technically difficult to use redox western blotting to analyze its redox status. although we have shown that trx , cancers , , of hk, and mtco might be involved in the synergistic cytotoxicity of af and ce combination, it would be important to knockdown trx , hk, and mtco to gain further insights into their respective roles and mechanisms in future studies. another important question is how ce could induce ros generation. it has been reported that ce might exert its anticancer activity by inhibiting akt, reducing bcl- , or elevating ros [ – ]. although we were able to show that ce could induce ros accumulation in colon cancer cells (figure c), the underlying mechanisms still remain unclear. a recent study by pritchard et al. suggests that ce could promote ros generation by disrupting mitochondrial respiration chain [ ], although the exact ce target in the mitochondria remained unclear. nevertheless, the ability of ce to induce ros accumulation in cancer cells seems to be a consistent finding. the ros stress induced by ce together with the intrinsic oxidative stress in cancer cells would put tremendous burden on the cellular antioxidant systems. a simultaneous inhibition of thioredoxin reductase by af would likely cause a collapse of the cellular redox system, leading to dysfunction of multiple redox-sensitive enzymes, inhibition of cellular metabolism and, eventually, cancer cell death. in contrast, normal cells are able to better maintain redox homeostasis due to their low level of basal ros generation. such a balanced redox status enables them to better tolerate exogenous ros stress owing to their high reserved antioxidant capacity, which can be mobilized to prevent the ros level from reaching the cytotoxic threshold [ ]. glycolysis and oxidative phosphorylation are the two main metabolic pathways that generate atp for the cells. our previous study has confirmed that af can affect glycolysis by blocking hexokinase activity [ ]. in the present study, we showed that af could decrease ecar in three colorectal cancer cell lines, while its combination with ce severely inhibited glycolysis activity likely through ros-mediated damage to hk. a loss of glycolytic activity would usually lead to a compensatory upregulation of oxidative phosphorylation to generate atp to support various cellular function [ , , ]. however, the combination of af and ce also inhibits mitochondrial respiration (figure ), likely due to severe ros stress. such double hits on the two energy metabolic pathways lead to a severe depletion of cellular atp, which occurred prior to cell death. the diversity in inherent difference in ros levels and redox status between non-cancerous and cancer cells provides a biochemical basis to develop redox-based therapeutic strategies against cancer [ , , ]. indeed, we observed that all three colon cancer cell lines were highly sensitive to af + ce combination treatment, whereas such a drug combination caused minimum cytotoxicity in normal colon epithelial cells (ccd ) and normal colon fibroblast cells (ccd ), confirming that this therapeutic strategy could preferentially kill cancer cells. selective induction of cancer cell death without harming normal cells is key to therapeutic success. we discovered that a combinations af and ce could produce a synergistic and selective anticancer effect on colorectal cancer cells. in particular, µm af in combination with µm ce seemed toxic enough against dld- colon cancer cells but appeared nontoxic to normal cells (figure s ). these results seem clinically relevant since af concentrations of – µm in plasma are achievable without obvious side effects in patients or in volunteer subjects who received the recommended dose of mg/day for rheumatoid arthritis [ , ]. similarly, plasma ce concentrations greater than µm are also achievable in human receiving mg/day, which seem well-tolerated [ , ]. this is also confirmed in mice bearing dld- xenografts, where af/ce combinations showed higher therapeutic efficacy than single drugs. since af and ce are currently used in clinic for other disease indications, it may be feasible to use these two drugs for potential treatment of colon cancer. . materials and methods . . cells and reagents all cell lines were purchased from atcc. dld- was cultured in rpmi medium (gibco, waltham, ma, usa), hct and ht- cell lines were cultured in mccoy’s a (modified) cancers , , of medium and lovo was cultured in ham’s f- k (kaighn’s) medium supplemented with % fetal bovine serum in a humidified conditions with % co at ◦c. auranofin and celecoxib were purchased from medchemexpress (monmouth junction, nj, usa). -acetamido- ′-maleimidylstilbene- , ′-disulfonic acid was obtained from thermo fisher scientific inc. (rockford, il, usa). dtt and h o were purchased from sigma-aldrich (st. louis, mo, usa). . . cell viability assay cell viability was measured using mts assay, as we previously reported [ ]. in brief, cells were seeded in a -well plate and treated with the indicated doses of celecoxib ( – µm), auranofin ( µm), or both for h. the optical density at nm was determined using a multiskan plate reader (thermo scientific, waltham, ma, usa). the combination index values were calculated using calcusyn software (biosoft, cambridge, uk). the ci values indicate a synergistic effect when < , an antagonistic effect when > , and an additive effect when equal to . . . apoptosis assay the number of apoptotic cells was analyzed by an annexin v/fitc (bd, franklin lakes, nj, usa) according to the manufacturer’s protocol. cells were harvested and analyzed on beckman flow cytometer (beckman coulter, miami, fl, usa). . . real-time cell metabolism assay xfe extracellular flux analyzer (seahorse bioscience, north billerica, ma, usa) was used for real-time analysis of extracellular acidification rate (ecar) and oxygen consumption rate (ocr) according to the manufacturer’s user guide. in brief, cells were seeded overnight in a seahorse -well culture microplate at density × per well. for ecar detection, the medium was changed to seahorse base medium supplemented with mm glutamine on the day of the assay and incubated for h in a co -free incubator at ◦c prior to the assay. injections of drugs (dmso, µm af, µm ce or both), glucose ( mm), oligomycin ( µm), and -dg ( mm) were loaded onto ports a, b, c, and d, respectively. for ocr detection, the medium was changed to seahorse base medium supplemented with mm pyruvate, mm glutamine, and mm glucose on the day of the assay and incubated for h in a co -free incubator at ◦c prior to the assay. injections of drugs, oligomycin ( µm), fccp ( µm), and rotenone/antimycin a ( . µm) were loaded onto ports a, b, c, and d respectively. results were normalized to cell number. . . measurement of cellular atp cellular atp concentration was detected using an atp-based celltiter-glo luminescent cell viability kit (promega, madison, wi, usa) according to the manufacturer’s instructions. in brief, × cells were seeded in -well plates and cultured overnight. cells were then treated with af ( µmol/l), ce ( µmol/l), or both for h. after drug treatment, µl celltiter-glo reagents was added to each well and rocked for min to lyse cell. the samples were kept at room temperature for another min. the atp contents were recorded as luminescent signal, using a luminescent plate reader (thermo fisher, varioskan flash, waltham, ma, usa). . . hexokinase enzymatic activity assay hk activity was measured using a hexokinase assay kit (sciencell research laboratories, carlsbad, ca, usa) according to the assay procedures recommended by the manufacturer. briefly, cells were treated with af ( µmol/l), ce ( µmol/l) or both for h, and cell extracts were prepared and performed for assay of hk activity using the reagents provided in the assay kit. cancers , , of . . measurement of cellular glucose uptake and lactate production cells were seeded in -well plates and cultured overnight. the culture medium was replaced with fresh medium containing af ( µmol/l), ce ( µmol/l) or both for h, and the culture medium from each well was collected for analysis of glucose and lactate contents using a biosensor analyzer (biology institute of shandong academy of sciences, jinan, shandong, china). . . thioredoxin- redox analysis redox analysis of trx was carried out as previously described [ ]. in brief, cells after treatment were washed with ice-cold pbs and collected by acid precipitation using ice-cold trichloroacetic acid ( %) for min at ◦c. samples were centrifuged at , × g for min and resuspended in ice-cold acetone ( %) and incubated for min at ◦c. remove acetone from tube by centrifugation at , × g for min and pellet was resuspended in lysis/derivatization buffer ( mm tris-hcl (ph ), . % sds, and mm ams) by sonication and incubated for h at room temperature. nonreducing sds polyacrylamide ( %) gel electrophoresis was performed to separate the oxidized and reduced trx . western blotting was performed using a rabbit anti-trx polyclonal antibody ( : dilution; abcam, cambridge, ma, usa) and goat anti-rabbit secondary antibody ( : , dilution; abcam). . . measurement of cellular ros cells ( × ) were seeded in six-well plates overnight and treated with af ( µmol/l), ce ( µmol/l) or both as indicated. then the cells were incubated with cmh dcf-da ( µmol/l) at ◦c for min. cells were washed twice with pbs, and cellular ros level were measured using a cytomix fc flow cytometer (beckman coulter, fullerton, ca, usa). . . western blotting antibodies for detecting human trx , mtco , atp a, uqcrc , sdhb, ndufb , akt, akt (phospho s ) and beta-actin were obtained from cell signaling technology (danvers, ma, usa) or abcam (cambridge, ma, usa). cells were washed twice with ice-cold pbs and lysed in lysing buffer. the concentration of proteins was normalized using a bca protein assay (thermofisher, rockford, il, usa). protein samples were run on a standard sds-page and transferred to pvdf membranes. subsequently, the membranes were blotted with specific primary antibodies overnight at ◦c. after that, the membranes were incubated with appropriate horseradish peroxidase conjugated secondary antibodies, and the signals were tested by the ecl detection system (thermofisher, rockford, il, usa). . . high-throughput screening assay the fda-approved drug library of drugs ( mm stock solutions in dmso, drugs/ -well plate, plates) was purchased from microsource discovery systems (gaylordsville, ct, usa). a high-throughput screening assay was performed as previously reported but with slight modifications [ ]. briefly, µl dmso was added to each well of drugs using aurora versa workstation to make a µm working solution. furthermore, cells were seeded in new -well plates using aurora versa reagent dispenser and grown overnight at ◦c, followed by µl of dmso, af, drug x, or their combination as indicated, and incubated for h. then, µl mts was added to each well and incubated for h and the optical density at nm was determined using a multiskan plate reader (thermo scientific, waltham, ma, usa). . . mouse experiments mouse experiments were reviewed and approved by the institutional animals care and use committee of sun yat-sen university cancer center (l g). . × dld- cells were injected subcutaneously into the right flanks of -week-old female athymic nude mice. after days, mice with tumors about mm in size were randomly assigned into six groups, each containing cancers , , of six mice. af was freshly prepared at mg/ml in olive oil. ce was freshly prepared at mg/ml and mg/ml respectively. mice were treated once a day by intragastric administration (except saturday and sunday) for days either with olive oil (vehicle), af mg/kg, ce mg/kg, ce mg/kg, or two combinations: af mg/kg + ce mg/kg or af mg/kg + ce mg/kg. tumor sizes were measured with electronic calipers and volumes calculated using the formula: (length × width )/ . body weights of mice were also recorded. at the end of the experiment, mice were sacrificed and their tumors were collected, photographed, and weighed. . . determination of mrna expression rna isolation was performed according to the manufacturer’s protocol (qiagen, hilden, germany). total rna was utilized for cdna synthesis using reverse transcription system kit (promega, madison, wi, usa) as described in the manufacturer’s instructions. cdna was used for quantitative real-time pcr (bio-rad cfx real-time pcr detection system, bio-rad laboratories, richmond, ca, usa) using specific primers in a sybr green reaction to determine mrna levels. the following primers were used to determine mtco mrna level. f: ′-ctgaacctacgagtacaccg- ′, r: ′-ttaattctaggacgatgg gc- ′. . . statistical analysis data were presented as mean ± sd. the statistical significance of differences was determined using the student’s t-test. p value < . was regarded as statistically significant. graphpad prism software (graphpad software, inc, san diego, ca, usa) was used for calculating these statistics. . conclusions a combination of auranofin and celecoxib has been identified as an effective regimen that is synergistically toxic to colorectal cancer cells. mechanistically, auranofin and celecoxib together induce severe oxidative stress and cause redox-mediated inhibition of glycolysis and mitochondrial oxidative phosphorylation, leading to energy crisis in cancer cells. supplementary materials: the following are available online at http://www.mdpi.com/ - / / / /s , figure s : quantitative comparison of cell death induced by af µm, ce µm or af µm + ce µm for h (based on figure c), figure s : quantitative comparison of colony formation in indicated groups (based on figure d), figure s : af/ce combination has minimum cytotoxic effect towards non-cancerous cells, figure s : the anticancer effect of auranofin (af) and celecoxib (ce) combination was independent of cox- expression, figure s : quantitative comparison of cell death induced by af µm, ce µm or af µm + ce µm for h (based on figure g), figure s : quantitative comparison of ros level induced by af µm, ce µm or af µm + ce µm for h (based on figure c), figure s : dld- cells were treated with indicated conditions for h, and cell extracts were analyzed by western blot for ndufb , sdhb, atp a, mtco and uqcrc protein. author contributions: conceptualization, r.x., p.l. and p.h.; funding acquisition, s.w. and p.h.; methodology, p.c., w.l. and w.d.; project administration, y.h., p.c. and y.z.; resources, p.l.; supervision, s.w.; validation, y.h. and y.l.; visualization, y.z.; writing—original draft, y.h.; writing—review & editing, y.h., p.l. and p.h. funding: this work was supported in part by research grants from the national natural science foundation of china (no. , no. , and no. ), and from guangzhou science and technology program ( , ). acknowledgments: we would like to thank ning meng, liyun liang, mingquan zhang, qiao liu and peiting zeng for technical assistance, and xin you for helpful discussions. conflicts of interest: the authors declare no conflict of interest. references . siegel, r.l.; miller, k.d.; fedewa, s.a.; ahnen, d.j.; meester, r.g.s.; barzi, a.; jemal, a. colorectal cancer statistics, . ca cancer j. clin. , , – . 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[crossref] [pubmed] © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . / .tx s http://dx.doi.org/ . /ijo. . http://www.ncbi.nlm.nih.gov/pubmed/ http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	introduction 	results 	high-throughput screening for drugs that synergize with auranofin against cancer cells in vitro 	auranofin and celecoxib synergistically induce colorectal cancer cell death in vitro 	combination of af and ce induced a severe energy crisis in cancer cells 	combination of ce and af caused inhibition of hexokinase enzyme activity 	af and ce combination induced severe ros stress leading to protein oxidation and dysfunction of mitochondrial electron transport chain 	auranofin and celecoxib exhibit synergistic therapeutic effect in vivo 	discussion 	materials and methods 	cells and reagents 	cell viability assay 	apoptosis assay 	real-time cell metabolism assay 	measurement of cellular atp 	hexokinase enzymatic activity assay 	measurement of cellular glucose uptake and lactate production 	thioredoxin- redox analysis 	measurement of cellular ros 	western blotting 	high-throughput screening assay 	mouse experiments 	determination of mrna expression 	statistical analysis 	conclusions 	references in forthcoming issues rimvydas silbajoris, "kristijonas donelaitis: a lithuanian classic" gary marker, "russia and the 'printing revolution': notes and observations" john-paul himka, "young radicals and independent statehood: the idea of a ukrainian nation-state, - " david lowe, "vladimir odoevskii as opera critic" thomas c. owen, "a new approach to the kurbskii- groznyi problem" patricia k. grimsted, "recent publications on archives and manuscript collections in the soviet union — a selected survey" discussion: daniel brower, "labor violence in russia in the late nineteenth century." comments by robert johnson, diane koenker, and ronald grigor suny to those wishing to submit manuscripts manuscripts for consideration should be submitted in four, double- spaced copies. footnotes should be double-spaced and placed at the end of the manuscript. manuscripts are sent to referees anonymously and should be prepared accordingly. library of congress transliteration should be used. in general, articles should not exceed twenty-five pages. manuscripts will not be returned unless postage is provided. the policy of the slavic review is not to consider materials that have been published or that are being considered for publication elsewhere. publication of articles in the slavic review is ordinarily limited to those submitted by members of the a a ass. nonmembers wishing to submit manuscripts are asked to request a membership application. sncew ai\d sigi\ificai\t titles ft&nv. e/meiy, & uiywity, education in the soviet union policies and institutions since stalin mervyn matthews an up-to-date and comprehensive survey of the successes and failures of education and training in the khrushchev and brezhnev years based on an objective assessment of the accessibility of the main types of institutions, content of courses, and soviet attempts to amalgamate their education system to their perceived economic and social needs. cloth-$ . july the end of social inequality? class, status and power under state socialism david lane the best available analysis of the true role of class stratification in state socialist societies and in particular the soviet union. professor lane's discussion ranges over such aspects as income and education differentials, the rise of white-collar occupations, the position of women and ethnic groups, and social mobility. cloth-$ . paper-$ . august soviet risk-taking and crisis behavior a theoretical and empirical analysis hannes adomeit foreword by marshall shulman detailed examination of the two berlin crises forms the empirical background against which com- parisons are made with the role of the soviets in other crises — in cuba, the middle east, in vietnam and in afghanistan — as well as with patterns of soviet intervention in eastern europe. cloth-$ . studies of the russian institute, columbia university russia at the crossroads: the th congress of the cpsu seweryn bialer and thane gustafson, eds. derived from the rand-columbia conference which used the party congress as a focus for scholarly analysis of the severe domestic and international dilemmas confronting the soviet union in the 's and the capacity of an aging soviet leadership to respond to them. cloth-$ . published under the auspices of the rand corporation and the russian institute, columbia university the economics of socialism, th edition principles governing the operation of the centrally planned economies under the new system jozef wilczynski a completely revised concise exposition of theoretical and practical elements of the operation of the planned economies in the ussr, eastern europe, and other socialist countries. special attention is given to economic reforms and recent developments. paper-$ . soldiers, peasants, and bureaucrats civil-military relations in communist and modernizing societies roman kolkowicz and andrzej korbonski, eds. a cross-disciplinary examination of the main theoretical, methodological, and empirical approaches to the study of civil-military relations in the middle east, in the socialist countries of eastern europe, and china. cloth $ . the middle east and the western alliance steven l. spiegel, ed. internationally recognized experts bring together different and distinctive perspectives on the arab israeli dispute, the dynamics of the energy crisis, alliance unity and the role of the soviet union, and the effect of growing middle east instability on the interests of individual allied countries. cloth-$ . center for international and strategic affairs, university of california, los angeles allen & unwin, winchester terrace, winchester, massachusetts ceas_a_ .. ++ full terms & conditions of access and use can be found at https://www.tandfonline.com/action/journalinformation?journalcode=ceas europe-asia studies issn: - (print) - (online) journal homepage: https://www.tandfonline.com/loi/ceas introduction: the european union, russia and the shared neighbourhood jackie gower & graham timmins to cite this article: jackie gower & graham timmins ( ) introduction: the european union, russia and the shared neighbourhood, europe-asia studies, : , - , doi: . / to link to this article: https://doi.org/ . / published online: aug . submit your article to this journal article views: view related articles citing articles: view citing articles https://www.tandfonline.com/action/journalinformation?journalcode=ceas https://www.tandfonline.com/loi/ceas https://www.tandfonline.com/action/showcitformats?doi= . / https://doi.org/ . / https://www.tandfonline.com/action/authorsubmission?journalcode=ceas &show=instructions https://www.tandfonline.com/action/authorsubmission?journalcode=ceas &show=instructions https://www.tandfonline.com/doi/mlt/ . / https://www.tandfonline.com/doi/mlt/ . / https://www.tandfonline.com/doi/citedby/ . / #tabmodule https://www.tandfonline.com/doi/citedby/ . / #tabmodule introduction: the european union, russia and the shared neighbourhood jackie gower & graham timmins the european union (eu) and russia’s ‘shared neighbourhood’ of ukraine, moldova, belarus, armenia, azerbaijan and georgia was, according to löwenhardt, writing in , ‘an economic and diplomatic battlefield’ (löwenhardt , p. ). the period that has followed has seen this agenda develop into a mainstream political debate on the prospects for european security and spill over into the military domain with the conflict in south ossetia in august . this conflict and the ukrainian energy crisis in january have contributed to the generation of a new post-cold war low point in eu–russia relations. apart from the frozen conflicts scattered around the region, it was not until the creation of the eu’s european neighbourhood policy (enp), initially outlined in , that attention began to focus on the states comprising the shared neighbour- hood. the enp was a strategy designed to extend a european zone of peace and stability eastwards, and it came in response to the imminent enlargement of the eu’s membership into central and eastern europe in . the enp was considered an essential step forward in establishing stable relations with its new neighbours, but, as haukkala has argued, russia’s self-exclusion from the enp has had the effect of creating a competitive agenda between the two actors (haukkala , p. ), and has failed to create the positive political dynamics that were intended. the launch of the enp had coincided with the re-election of vladimir putin as russian president and the projection of a more assertive russian foreign policy agenda. russia had failed to prop up the shevardnadze regime and to prevent the saakashvilli government coming to power in georgia’s ‘rose revolution’ in autumn , and had likewise failed to divert the ‘orange revolution’ in ukraine which brought the more pro-western candidate, viktor yushchenko, to power after the original elections in december were declared void. the view from moscow towards the enp and the very concept of a shared neighbourhood was thus increasingly driven by the perception of a threat from western encroachment into what russia considered to be its traditional sphere of influence. where the states in the region are themselves concerned, there is an obvious tension between, on the one hand, the attractions of a pro-western agenda which promises aid, technical assistance and eventual integration into the single european market if not membership, and which would have positive benefits for trade and investment, and europe-asia studies vol. , no. , december , – issn - print; issn - online/ / - ª university of glasgow doi: . / on the other hand, cooperation with moscow given their dependency on russian energy supplies, as well as the cultural and historical affinities that many of the states share with russia. although both the eu and russia have a common interest in regional stability, what we have seen in recent years is the gradual re-emergence of zero-sum calculations and geopolitical competition. it cannot come as any real surprise that both the eu and russia have expressed an interest in the shared neighbourhood given the geographical location of the region, and trenin is correct in his assertion that the tensions we are currently witnessing do not necessarily translate into old-style cold war conflict. what, however, is clearly the case is that the ‘overall state of eu–russia relations will be a key variable in the future development of the countries that lie between them’ (trenin ). the common space on external security created by the eu and russia in has so far failed to produce tangible results, and it remains to be seen whether the eastern partnership, launched in may , will provide a more productive framework for political agreement on regional cooperation and stability, and whether strengthening the eu’s relations with its eastern neighbours will facilitate improve- ments in the eu–russia political relationship. as the polish foreign minister, radosław sikorski, has argued, if we see russia’s future as being in partnership with the european union, we cannot deny the same prospect to the people of the countries that make up the joint neighbourhoods of both. it would be a poor solution for the eu and russia to be separated by a region whose contacts with europe are less substantial than those it has with russia. (sikorski , p. ) the contributions to this collection have emerged out of a series of academic activities convened by the eu–russia joint research network during the – academic session, an initiative which has been joint funded by the british association for slavonic and east european studies (basees) and the university association for contemporary european studies (uaces). derek averre provides the opening contribution with an examination of the competing rationalities of russian and eu foreign policy in the shared neighbour- hood, and argues that there is a deep-rooted incompatibility between the eu’s use of post-modern, normative power and russia’s use of modern, structural power, an incompatibility which sets out a range of complex challenges in developing any tangible meaning to the concept of ‘strategic partnership’ between the two actors. stefan gänzle’s examination of the eu’s security governance strategy towards its eastern neighbours suggests that the european neighbourhood policy (enp) employed by the eu comprises a dynamic which ultimately will bring some neighbouring countries closer to eu membership. martin dangerfield’s evaluation of the internal dynamics of the eu’s eastern policy-making, and the specific contribution made by the ‘visegrad group’, the czech republic, hungary, poland and slovakia, argues that there is mixed evidence regarding the extent to which these states have been able to influence the development and projection of the eu’s eastern policy, and the newly-established eastern partnership in particular. three contributions focus on the development of eu–russia relations. hiski haukkala provides a discussion of why the eu has failed to influence russia’s jackie gower & graham timmins development, and argues that situational characteristics have forced the union into some rather difficult trade-offs between securing its normative agenda and developing a relationship with the at times turbulent and unpredictable russia. rick fawn discusses the human rights dialogue between the eu and russia, and contends that human rights have taken an instrumental dimension in relations between post-soviet states, in particular the russian federation, and several of the post-communist states that achieved membership of the eu and nato. tuomas forsberg and antti seppo consider the eu–russia relationship from the perspective of recent trade disputes and assert that although the lack of unity has been a very common explanation for the failures of the eu foreign policy, the poor success in solving these disputes cannot be explained purely in these terms and requires a broader debate regarding the contextual nature of power resources which highlights the dependence of the eu on russia’s energy resources. finally, mikhail filippov looks at the georgian crisis of , and suggests that moscow’s strategy has been rooted in an attempt to create diversionary conflicts in the region, which are intended to disrupt the perusal of a western agenda by the states concerned. the editors wish to acknowledge and thank basees and uaces for their generous financial support which enabled this collection of essays to be developed, the contributors for their efforts in producing such an impressive collection of academic research essays, the reviewers for their assistance in the editorial process and, in particular, terry cox and sarah lennon for their support and seemingly unlimited patience in guiding this project through to completion. king’s college london university of stirling references haukkala, h. ( ) ‘the russian challenge to eu normative power: the case of the european neighbourhood policy’, the international spectator, , . löwenhardt, j. ( ) stuck in the middle: the shared neighbourhood of the eu and russia, – (the hague, netherlands institute of international relations). sikorski, r. ( ) ‘the eu’s ‘‘eastern partnership’’ is the key to relations with russia’, europe’s world, , summer. trenin, d. ( ) russia, the eu and the common neighbourhood (london, centre for european reform), september, available at: http://www.cer.org.uk/pdf/essay_russia_trenin_sept .pdf, accessed august . introduction http://www.cer.org.uk/pdf/essay_russia_trenin_sept .pdf geophysical surveys in northeast pacific: abstract; geology and potential development of queensland oil shales: abstract; eruption of mount st. helens: abstract; international mapping activities of the world: abstract association round table most of antarctica is ice-covered, and rock exposures com- prise only some to % of the area of the entire continent. an- tarctica is divisible into two regions with different geological characteristics. east antarctica (lying mainly in east longitudes) is the larger region, and west antarctica the smaller. tlie trans- antarctic mountains, which cress the continent and pass near the south pole, mark the inland border of east antarctica. east antarctica is a continental shield that was a central piece of gondwanaland in early mesozoic time, the basement rocks are mainly of precambrian age although lower paleozoic rocks are also present in the transantarctic mountains. archean rocks in the charnockite-enderbite terrane along the indian ocean coast have yielded apparent ages as great as . billion years. the basement complex is unconformably overlain by the subhorizontal gondwana sequence of devonian-jurassic age. west antarctica is a younger region that makes up a segment of the qrcum-pacific mobile belt. definite precambrian rocks are known from only one locality, and the ice sheet-bedrock contact is below sea level throughout much of west antarctica. sedimentary rocks, mainly or entirely of phanerozoic age, crop out extensively in the antarctic peninsula, the ellsworth moun- tains, and western marie byrd land. diverse phanerozoic ig- neous and metamorphic rocks are widely distributed across west antarctica, especially mesozoic (andean) intrusive bodies and cenozoic volcanic rocks. currie, ralph g., and r. p. riddihough, survey canada, sidney, british columbia, canada geophysical surveys in northeast pacific geol. the major tectonic and geological boundaries in the north- east pacific off british columbia have been delineated by muhiparameter geophysical surveys conducted by the pacific geoscience centre. systematic magnetic, gravity, bathymetric, and seismic surveys on mi ( km) lines run perpendicular to the shelf edge to a distance of mi ( km) offshore, sup- plemented by detailed surveys, heat flow, ocean bottom magnetic and seismic measurements, sedimentological and geological studies, have been used to produce an integrated pic- ture of this very complex environment. major components include: the queen charlotte transform boundary, a complex continental slope averaging mi ( km) wide with an associated - mgal free air anomaly centered over the outer part of the slope suggesting that the slope is largely composed of sedimentary material; adjacent ocean floor with characteristic north-south-trending magnetic linears which are complicated by anomalies associated with the kodiak-bowie seamount chain and transform discontinuities, and the northern juan de fuca and explorer plate region, an area of short spreading ridges with a history of plate fragmentation, rotation, and subduction beneath the north american plate. these studies have resulted in a revised model of the evolution of the western canadian continental shelf, which has implica- tions for petroleum exploration and potential. designers of petroleum exploration strategies for all active margins must be cognizant of plate dynamics. recent reports of ridge axis polymetallic sulfide mineralization also illustrate the potential economic importance of regional studies of plate boundaries and behavior. day, r. w., geol. survey cjueensland, brisbane, queensland, australia geology and potential development of queensland oil shales stimulated by recent interest in oil shale as an alternative source of oil, exploration since has revealed that the ter- tiary and cretaceous oil shale deposits of queensland are of considerable size and extent. tertiary deposits contain inferred resources of oil totaling , x ^ m? ( billion bbls), based on average fischer assay yields of to l/t in situ, while cretaceous deposits are perhaps one hundred times larger. however, % of the latter are too deeply buried to be extracted with existing technology. on present information, jurassic, per- mian, and cambrian oil shale deposits do not appear to be of economic significance. cretaceous oil shales occur within the shallow marine toolebuc formation of western queensland. this stratigraphic unit is thin ( to ft, to m) but exceedingly widespread. tertiary oil shales, which range up to , ft ( m) in thickness, formed in freshwater environments in several basins located in the eastern one-third of the state. oil shale deposits most likely to be exploited in the next decade are those of tertiary basins close to the coast, which con- tain multiple seams of high oil yield, amenable to open-cut min- ing and with adequate supplies of water. the condor, rundle, stuart, and yaamba deposits are in this category. mining feasibility studies of these and the cretaceous julia creek deposits envisage open-cut mining and surface retorting on a large scale. experimental retorting investigations are in progress. extraction of oil from oil shales in areas remote from the coast probably awaits development of economic methods of in-situ retorting. decker, robert, u.s. geol. survey, hawaiian volcano observatory, hawaii eruption of mount st. helens (no abstract) delany, frances m., secretary general, cggmw international mapping activities of the world (no abstract) de la paz, wenceslao r., and alfredo c. tron- calbs, bur. energy development, ft. bonifacio, metro manila, philippines, and chester f. budd, union oil co., los angeles, cmifornia philippine geothermal energy resource: an available in- digenous alternative the philippines is indeed fortunate to be located within the west pacific island arc dotted by neogene volcanic centers. the multistage development of volcanic-plutonic events in this western part of the circum-pacific basin has generated regions of high heat flow where known potential geothermal resources are located. with the increasing power demands reflecting a favorable growth of the country's economy, the philippine government embarked on an accelerated program to harness the country's geothermal energy for power utilization at the start of the energy crisis in early te. for a period of years ( - ), the philippines has suc- cessfully launched a systematic and continuing program of assessing, exploring, developing, and exploiting its vast potential geothermal resources. of the several potential areas scattered all over the archipelago, four geothermal fields have already con- tributed some megawatts equivalent to almost % of the total electrical power supply of the philippines. this paper deals with the geothermal resource development of ijsrd - international journal for scientific research & development| vol. , issue , | issn (online): - ijsrd - international journal for scientific research & development| vol. , issue , | issn (online): - all rights reserved by www.ijsrd.com sustainable assessment of solar electromechanical devices jitisha aggarwal student of b.tech department of electronics engineering ymca university of science & technology, faridabad- abstract— during this century, economic development for a better standard of living has been instrumental in deteriorating the environment. indians are now consuming more resources than ever and polluting the earth with waste products. environmental stability is an important issue that receives much attention today.solar photovoltaic cells are an active system in which small panels faced with semiconducting material turn sunlight into electricity. in the present work, solar photovoltaic based low load stepper motor and medium load kwh power supply for home utilities, have been designed and fabricated for various electromechanical applications. its technical and economical viability was tested. it consumed power from sun and hence it is cheaper and environmental friendly. the paper stresses the utility of solar powered motor. key words: light load mechatronics applications, medium load household/industrial applications, solar photovoltaic cells i. introduction the past century has seen an exponential increase in the demand for energy. the increase in energy use is primarily the result of the rapidly growing world population using an increased amount of technology that requires a greater amount of energy to sustain it. the majority of current energy demand is being satisfied by energy sources that are finite, namely, fossil-based fuels. renewable energy technology bridges the gap between mounting global energy demand and supply of finite conventional energy sources. photovoltaic’s is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. photovoltaic power generation employs solar panels composed of a number of solar cells containing a photovoltaic material. mark bridges, et al, ( ), highlighted the small amount of research that has been conducted into the environmental noise impact for coal processing plants. another important reason is provided by the authors for studying the impact of noise in the industrial workplace, this being that the maximum noise exposure allowed for a worker is db equivalent continuous exposures for an eight hour period. noise and vibration from individual equipment items can be further reduced by appropriate design, maintenance and isolation of sound power sources. though a lot of work has been done on solar inverter and solar energy but only limited work has been done for its application in electromechanical devices of various light load and medium load applications. the present research work discusses the fabrication and saving obtained from solar based light load motor and medium load household/industrial applications for cheaper and environmental friendly operation. ii. experimental set- up the specification and size of various equipments are as follows (table i & table ii): s.n. part name specification remarks voltage regulator - v for various motors. solar panel photovoltaic (pv) cells( v output ), charging . - . a/hour battery v ,dc, ah motor rating v dc, v dc and v dc timer with resistances and capacitors for automatic on/off applications. ac adapter input: - v ac, . a- . a output: v dc, . a energy to be supplied by ac adapter if sunlight is not available. table : details of solar electromechanically device for light load s.n . part name specification remarks solar panel photovoltaic (pv) cells, v output pmax= x = w vmp= . v imp = . a battery v dc, ah no. inverter i kwh ,sine wave ac - v solar charge controlle r rated voltage= v rated current= a capacity w sustainable assessment of solar electromechanical devices (ijsrd/vol. /issue / / ) all rights reserved by www.ijsrd.com load type colour tv: v,lcd computer/laptop= w, washig machine = w, lamps= w table : details of solar electromechanically device for medium load iii. results and discussion a. light load mechatronics applications: ) stepper motor specifications: stepper motor getting power from battery: ( v, . a). battery storage capacity= v, . a. charging rate = . ampere/hour battery charging time= hrs energy saving for one hour operation= x . = watt hour energy saving for hour operation/day = x . x = watt hour energy saving for day operation= x = watt energy saving by one motor in a year = . x = . kwh fig. : solar system with lights and battery inside red colour box practically, there may be many such motors and energy saving is much higher. total cost of solar electromechanical device was rs. but there was no running cost. besides d.c.motor, other solar lighting devices such as cfl, led’s and mobile chargers were also operated from the energy stored in battery from solar panel(fig. ). it is established that the solar run motor may find applications in growing utility of mechatronics equipments and provide solution of energy in various household utilities. the above system was designed to give a daily working time of - hours with the fully charged battery. the system provided for buffer storage for - appliances ranging from - volts. in cloudy summer/rainy season/winter season (when there is no sun), we have additional stand-alone system i.e. an electrical charge of specification ( v, . a) is used for light load system. b. medium load household/industrial applications: ) specifications: motor getting power from battery: upto kwh. such motors are used in washing machine, computers, lamps, mobile charger, water lifting pumps, fan, desert cooler, etc. battery storage capacity= v, ah. four solar panel of w were installed on roof top at an inclination. energy saving by ikwh motor for hour operation/day= x = watt hour energy saving for day operation= x = watt hour energy saving by the motor in a year = x = kwh electricity bills comes down by - % just by installing kwh solar system.morever, it gives back up when there is no electricity. total cost of solar soar panel, storage batteries, inverter for converting dc into ac, electromechanical device was rs. , , lakh but there was no running cost. besides motor, other solar lighting devices such as cfl, led’s and mobile chargers were also operated from the energy stored in battery from solar panel. electricity generated from thermal power station is an expensive source of electricity; solar energy has turned it into an economical power source in the long-run. the amount of electricity generated from solar energy depends upon the available sunlight. the biggest advantage of using solar power is that it is an inexhaustible source of energy. once you have installed the system, you don’t have to worry that you would ever be without electricity because the sun is always going to be there. the next advantage of using solar energy is that it doesn’t emit any pollution into the environment. solar panels don’t release any emissions into the atmosphere while generating electricity. in the most remote locations, solar energy is the ideal source of electricity. a big advantage of solar energy systems is that a properly installed system doesn’t require much maintenance. electricity generated from thermal power station is an expensive source of electricity; solar energy has turned it into an economical power source in the long-run. iv. conclusions the paper determined the feasibility of reducing greenhouse gas emissions by the use of connected photovoltaic (pv) power systems, whilst at the same time demonstrating the technical and economic viability of this new power technology to supplement traditional sources of electric power. it was established by testing the system during last months that if charged for - hrs in sun light summer, battery is capable to supply stored energy to a stepper motor of v, . and a set of equipments such as led’s ,cfl( w) , mobile chargers for - hours for light load mechatronics applications. for medium load applications, the solar system is capable of supplying energy upto ikwh and it is going to be economical in long run because there is no running cost. the developed solar system is portable, environmental friendly and free from maintenance. it is established that the solar run motor may find applications in growing utility of mechatronics equipments and provide solution of energy in all household utilities. sustainable assessment of solar electromechanical devices (ijsrd/vol. /issue / / ) all rights reserved by www.ijsrd.com v. references [ ] jitisha aggarwal, and m. l. aggarwal, , " harnessing solar energy for every home: energy saving applications", open access journal: conference papers in science, article id , pages, . doi: . / / . [ ] m. gonzalez, f.j ferrero, j.c. anton and m.a. perez ,”considerations to improve the practical design of universal and full-effective nicd /nimh battery fast-chargers”,applied power electronics conference and exposition, , vol. , pp. – . [ ] ankit gupta, ( ), “safety measures for reduction of failure in belt conveyor for thermal power plant”, international journal of mechanical engineering and robotics research, vol. , no. .pp - . [ ] aaron d. machine design. rd ed. macmillan publishing co.; . [ ] dhull s. and aggarwal m.l. ( ). “automation in material handling system for light load applications”, fourth national conference on recent advances in manufacturing nit surat, pp - . [ ] yadav sonu , aggarwal m.l.,” effect of lifting load on solar powered screw jack design in automotive vehicles”, international journal for scientific research & development , vol. , issue , , pp - . wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ federal barriers to energy resource development: abstract; shallow subsurface dolomitization of subtidally deposited carbonate sediment in hanson creek formation (ordovician-silurian), central nevada--evidence for groundwater mixing: abstract; appli... association round table the crystalline igneous and metamorphic rocks of the precambrian basement, the paleozoic and mesozoic sediments of the beacon group, and the cehozoic and recent volcanic rocks have been examined. localized concentrations of radioactive minerals have been de- tected in precambrian rocks, but only small concentra- tions have been found associated with pegmatites. thus far, the area covered by the radiometric survey has been too limited to provide any detailed assessment of the uranium resource potential of antarctica. in gen- eral, however, it appears that the potential for uranium resources in the ice-free areas is essentially the same as that of the surface area of any other continental land- mass. dresher, william h., univ. arizona, tucson, ariz. federal barriers to energy resource development it has been almost years since the american people suffered the rude awakening to the fact that its energy supply no longer was in united states control. since that time, the american people have witnessed a circus- like performance of institutions, political movements, and individual politicians, both local and national, as they have used the energy issue as a vehicle to achieve their goals to reorder society and to jockey for a redis- tribution of power. the energy "crisis" has been manna from heaven for the common denominator for most of the evils which it seeks to correct in our society. the net result of actions taken to correct the energy problems has been a barrage of recommended and enacted regu- lations which, rather than improve energy supply, act to inhibit it severely. more often than not actions taken by the federal government in the name of correcting the energy problem are more oriented toward increasing the severity of the problem. federal policies and regulations which act to inhibit energy-resources development range from limitations and restrictions to the exploration for energy resources to the development of new technologies to create and use energy. every step in the process of discovering, producing, delivering, and using energy has come under federal control by a myriad of federal agencies. as a technologist and a pragmatist, it is hard for me to accept the "crisis" atmosphere of the energy issue when so many are accepting the proclamation of so few that "up" is "down" and the "moon is made of green cheese." it is time for thinking people to knuckle down and to dispel the energy myths with truth and fact in order that we, the american people, can get on with our business of assuring ourselves a viable future as an in- dustrial society based on the free enterprise system. i fear that if we falter on this mission it will mean the end of the standard of living and the personal freedoms we have worked so hard to establish and to maintain in the united states of america. dunham, john b., union oil research center, brea, calif., and eric r. olson, petrocanada, calgary, alta. shallow subsurface dolomitization of subtidally de- posited carbonate sediment in hanson creek for- mation (ordovician-silurian), central nevada—evi- dence for groundwater mixing stratigraphic sequences of the hanson creek forma- tion are grouped into two categories based on differing paleogeographic settings and diagenetic histories. se- quences in northeastern eureka county record deposi- tion in shallow subtidal to peritidal environments. re- placement dolomitization was the main diagenetic process affecting the original calcium carbonate skeletal grains, ooids, and mud. lack of associated evaporite minerals or their pseudomorphs precludes sabkha dia- genesis. stratigraphic sequences in southwestern eureka county consist of laihinated carbonate and shale of moderately deep-water deposition, succeeded by a shoaling-upward sequence capped by oolitic grainstone. stabilization of original carbonate sediment to low- magnesian calcite was the main diagenetic process af- fecting these rocks. thin sections stained with potassium ferricyanide in- dicate that fe+ + did not have a role in the formation of hanson creek dolomites. sr+"'" concentrations of the dolomites ( to ppm) are much lower than values reported for holocene dolomites. the low values indi- cate reaction with solutions of strontium/calcium ratio lower than that of seawater. for hanson creek dolo- mites, " values range from — . to - . parts per thousand pdb. such distinctly light values reflect the influence of solutions depleted in o'* relative to normal seawater. the data suggest that dolomitization occurred in the shallow subsurface as a result of the mixing of meteoric-derived groundwater and marine pore water. intrusion of fresh water into subtidally deposited sedi- ment took place as a result of lateral extension of fresh- water lenses developed beneath subaerially exposed tracts of the inner carbonate platform. dolomite-to- limestone transitions mark the lateral extent of freshwa- ter lenses in the subsurface. undolomitized deeper wa- ter carbonates of southwestern eureka county, remote from areas of freshwater recharge, were positioned be- yond the greatest lateral extent of freshwater lenses and were not subjected to the early influence of meteoric derived groundwater. dunlap, john b., jr., paleodata inc., new orle- ans, la. applied biostratigraphy, south louisiana and gulf of mexico paleontologic control in south louisiana and the ad- jacent gulf of mexico is among the best in the world. with this control it is possible to construct relatively detailed paleogeographic maps and interval-isopach maps based on biostratigraphic markers. careful study of these maps clearly defines areas having maximum potential for hydrocarbon accumulation. currently ac- cepted biostratigraphic units as defined by foraminif- era range in age from paleocene through pleistocene. dutton, shirley p., bur. econ. geol., austin, tex. facies patterns and depositional models, pennsylva- nian system, palo duro basin, texas panhandle wps volume issue cover and back matter w o r l d ' s p o u l t r y s c i e n c e j o u r n a l volume february - april number editor production manager miym.c.freach, dr. r. f. gordon, cm. ware lane, b.o.c.m. silcock, wyton, poultry development farm, huntingdon pe bz. risborough road, england. stoke moadeville, aylcsbwy, bucks, england. associate edlrors prof. r b. cumming, austra!ia dr. werner hartmann, w. germany dr. w. e. shaklee, u.s.a. dr. j. e. lancaster, canada dr. p. merat, france switzerland mr. c. m. ha", u.k. dr. w. j. mue- u s a . dr. m. -v. u.s.s.r dr. werner t h o m a " , mr. a. thumim, israel dr. y. yamada. japan published quarterly by the world's poultry science association seartary and asst. treasurer: dr. r coles, tmramleon, biddja, malta, . c treasurer and asst. !kcr&uy: dr. r. george jaap, ohio state university, west lane avenue, columbus, ohio, u.s.a. . the world's poultry sdencc journal, oflbciai organ of the world's poultry sdence association, is sent to all members in good standing. owing to rising costs of publication, subscriptions to non-members will be $ (or i u equivalent in other currency) per year as from st january . all items pertaining to production, advertisii and mailing should be addressed to miss m. c. french, world's poultry science association, b.o.c.m. silcock. poultry development farm, risbomagh r% stoke mandeville. ayksbury, bucks, england. manuscripts and items regarding content of the journal should, be addrased to jk. r. f. gordon, c.b.e. , ware lane, wyton. huntingdon, pi bz. england. available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core owicers of the world’s poultry science association president: dr. a. william jasper (usa). hon. part presidents: dr. h. h. alp (usa), prof. j. a. castello llobet (spain), dr. r. cola (england), prof. e. e. penionzhkevich (ussr), mr. alex wiltzer (france). senior vice-president: dr. d. h. shrimpton (uk). vice-presidents: mr. h. kbbell (switzerland), dr. v. i. fisinin (ussr). president of the european federution: prof. s . scholtyssek (germany fed.). representative ofthe xwth world congress: dr. joao de faria burnier (brasil). secretary and assistant treasurer: dr. r. a l e s (malta). treasurer and assistant secretary: dr. r. george jaap (usa). editor: dr. r. f. gordon (uk). journul production manuger: miss m. c . french (uk). members qf council: argentine: ir. m. f. bonino, (two vacancies). australia: prof. r. b. cumming, mr. j. freebairn, dr. a. johnson, dr. m. w. mcdonald, mr. r. h. morris, mr. w. nowland, miss s. peters, mr. g. slcnnett, mr. w. stanhope, mr. s. wilkins. belgium: prof. c. h. van den noortgaete, prof. n. reyntens, dr. f. van wambeke. brasil: dr. b. morais m. de andrade, dr. j. h. da silva bernardo, mr. r. b. costa, dr. s. firace, dr..h. katayama, dr. jose m. lamas, cel. d. marques, dr. r. m. de miranda, dr. f. a. toledo piza, mr. f. tanabe. canada: dr. r. b. buckland, prof. d. r. clandinin, mr. m. s. mitchell, dr. c. riddell, dr. j. d. summers. colombia: (vacancy). czechoslovakia: dr. v. peter, mr. s . studeny. denmurk: prof. j. fris jensen, prof. h. e. marthedal, mr. v. petersen. finland: mr. k. eklund, prof. k. maijala, mr. j. j. tiitola. france: dr. j. aycardi, dr. c. calet, dr. c. meurier, mr. r. pero, (one germuny (ddr) : prof. h. brandsch, mr. e. anders. germany (federal) : prof. a. mehner, prof. h. schlutter, prof. s. scholtyssek, greece: dr. n. p. zervas. hong kong: mr. thomas kae sang yip. hungary: dr. y e r horn, mr. tibor schuller. h&a: dr. l. karachan, dr. c. m. sin&. israel: mr. z. ben-adam, mr. i. doron, mr. d. genten, prof. m. perek, mi. . raviv, mr. y. rosenberg, dr. m. taran, mr.,m. yedlin, dr. a. livschutz, mr. a. thumim. mr. a. . moll (australia), mr. l. von schmidt (brasil). vacancy). prof. r-m. weper. available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core new year’s message from the president hange is constant and time flies! it has been over two years c since the usa branch staged a successful congress in new orleans. our eyes are now focused on the next congress in rio de janeiro. having had the privilege, since new orleans, t o participate in wpsa meetings and conferences and meet many of our members on four continents, i am deeply impressed with the wide variety of wpsa activities around the world and the wide dedication to wpsa objectives. in reflecting on wpsa activities and the objectives of our asso- ciation, it becomes obvious that we must be concerned with the challenge of helping to feed the world. the poultry industry has performed remarkably well in this respect. but, the challenge remains. therefore, as we start the new year, i would like to share some thoughts with you on this vital subject. some commentators say that a long-term shortage of food could make any energy crisis look like a picnic. researchers generally agree that unless there is a reduction in the rate of population growth there will be no solution to the long-range world food problem. it is significant that a t the world population conference in , countries unanimously agreed to two principles: first, that it is the right of all citizens to have knowledge as t o how they might have the number of children they desire.. . and, that it is the responsibility of every government to see that its citizens have this knowledge. today about one-fifth of the people in the world are well fed while about four-fifths are poorly fed. if current birth rates continue, the world’s population is expected to expand from the currently estimated billion t o around . billion in the year , . eighty percent of this increase will occur in africa, asia, and latin america- the areas least able to feed and support such a population. statements such as these lead to pessimistic views of what world food supplies for the future will be for many people. many agri- culturalists believe that a partial solution lies in the expansion of present technology in animal production. the developing countries have about % of the world’s domestic livestock and fowl. yet these same countries produce only about % of the world’s supply of meat, milk and eggs. animal foods can help solve the problem of food shortage in three ways. these foods provide quality nutrients needed for human diets. they can be produced efficiently. and animals (including poultry) grown for food can help improve the environment. available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core editorial e would like to take this opportunitv of wishing all our members w a happy and successful . we would, however, commend our readers to the more solemn comments on the association’s duties in the new year message from our president, and in the items of prof. j . a. castello’s report to the executive committee on p. of this issue. we apologise t o contributors for the delay in publishing their papers but continued inflation dictates the number of papers per issue as a result of increasing postal rates. may we request contributors to supply copies of summaries of their papers? this is essential if translations are to accompany the english summary. we would also draw the attention of branch secretaries to the latest date for inclusion of branch notes and to remember that if notification of “forthcoming meetings” are to reach readers in time t o be meaningful they should appear in the issue prior to the quarter in which the meeting is to be held. our printing schedule for is:- last date for receipt of material. issue . . issue . . issue . . and issue ( ) . . . this does not apply t o scientific articles which are a t present well in hand and can be with the printer immediately the previous issue has been completed and in time for page proofs to be out to the authors for correction and return. please do not let this detract from the sub- mission of papers. our thanks are due to our translators dr. w. hartmann and dr. p. merat for their continued help and indeed to all our contributors and branch federation group secretaries. available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core green energy community with smart society for sustainable living energy procedia ( ) – available online at www.sciencedirect.com sciencedirect - © elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of coe of sustainalble energy system, rajamangala university of technology thanyaburi (rmutt) doi: . /j.egypro. . . th eco-energy and materials science and engineering ( th emses) green energy community with smart society for sustainable living r. rodprasert , t. chandarasupsang , n. chakpitak , and p. p. yupapin f* faculty of knowledge management, college of arts media and technology, chiang mai university, chiang mai , thailand p & a technology center, / supakorn village, sainoi district, nonthaburi , thailand abstract we propose the conceptual model of incorporative energies and technologies, which they are designed for a smart society that can be established under the use of green energy concept for sustainable living. basically, the use of natural resource with green environment and sustainability has become the critical issue of the world society, where the sustainable energy resources such as solar cells, wind energy and wave energy have been the promising target requirements. the smart society with green energy suppliers can give the modern society living facilities, where the sustainable life is the advantage. in this paper, the incorporative appliance between green energy and smart society is designed and the conceptual model discussed. this proposed concept can be planned, implemented and realized in the near future. keywords: information management; green energy community; energy management; sustainable energy; energy policy © the authors. published by elsevier ltd. peer-review under responsibility of coe of sustainalble energy system, rajamangala university of technology thanyaburi (rmutt). * corresponding author e-mail address: panda.yupapin@gmail.com © elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of coe of sustainalble energy system, rajamangala university of technology thanyaburi (rmutt) http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf r. rodprasert et al. / energy procedia ( ) – . introduction energy consumption has been the essential factor for the world society, where the power consumption of the world has been increased and caused the energy crisis since the last few decades (madan, pant, kumar & arora, ; oliveira & fernandes, ; rio & burguillo, ), in which the fossil fuel cost violation was affected to the world economy violation. till date, the economical collapses have been occurred in many countries due to the energy crisis around the world (chard, caton, rana & bubendorfer, ; frid, andonegi, depestele, judd, rihan, rogers & kenchington, ). since, the use of fossil fuel has become the problem of the world economy (cada, ahlgrimm, bahleda, bigford, stavrakas, hall, moursund & sale, ; frid, andonegi, depestele, judd, rihan, rogers & kenchington, ), where the alternative and renewable energy have been the targets for sustainable energy resources. solar cells have shown the promising indication that can be supplied to the world demand, in which the high performance solar cells device has shown the positive response to the world (bochlert, mcmurray, & tortorici, ; lovich, & ennen, ; srithanachai, ueamanapong, niemcharoen & yupapin, ). ). moreover, the use of wind and wave energy has also been increased and reported the convincing applications (frid, andonegi, depestele, judd, rihan, rogers & kenchington, ; smeets, faaij, & lewandowski, ; kahraman, ; zongrui, yuanxiong, dapeng & yuguang, ). the searching for new energy resources and systems that can be used with environmental friendly and sustainable consumption is the interesting task. in this paper, we present the use of green energy concept that the sustainable energy consumption without world environmental damage is the required target, in which solar energy, wind energy and wave energy are proposed incorporating the modern city environments. the hybrid energy system is the key concept for sustainable consumption and environment. by using the solar cells incorporating the alternative resources, for instance, wind and wave energy, all electrical power supplies can be operated for the society demand, where the information technology facility can be coverage, which will be described and discussed in details in the following sections. . sustaiable energy concept merging solar-wind and wave energies green energy such as wind, solar and wave energies have become the sport light for using as the backup power systems because they have shown the unique characters as shown in figures - , the wave energy generation is as shown in figure , where wind generation is described by the weather characteristics as shown in figure , the street lamps supplied by solar cells are as shown in figure . the solar system can produce energy from sun light for street lamps as shown in figure , which is suitable for the area that has long sun light period. limit of solar system is that it cannot generate the energy in the shade areas, for instant, at night time or raining season, in which the other energy resources are required. meanwhile, win energy is suitable for the area such as sea side or cooling zone, so win energy always uses with solar system as an alternative energy system (frid, andonegi, depestele, judd, rihan, rogers & kenchington, ). another energy resource is the wave energy system which uses the benefit form wave in the ocean to create the energy (frid, andonegi, depestele, judd, rihan, rogers & kenchington, ), which can be used both with sea land and island areas. figure : wave energy generator using oyster wave energy system connected to land power system r. rodprasert et al. / energy procedia ( ) – figure : weather characteristics and wind generation figure : street lamps supplied by solar energy (cells) sea-land-island power station based on the characteristics of each energy system, which is shown that most of suitable areas that the sustainable energy systems are sea land or island areas because the sea land has the geographic character for energy system (cada, ahlgrimm, bahleda, bigford, stavrakas, hall, moursund, & sale, ). moreover, the industrial sector near the sea port area is recommended to use for the investment cost reduction, or the island that hard to supply the electricity cable with the main land. therefore, the sustainable electricity turbine system can be used to substitute the limitation of wire electricity system from the main grid. r. rodprasert et al. / energy procedia ( ) – figure : power system which is combined by wave wind and solar energy generators moreover, the characteristic area of sea land and island is suitable for sustainable energy, in which the weather characteristics are suitable for wind generation. the combined power system using wind and solar systems is as shown in figure , which is suitable for sea land and island power supply. figure shows that wind from sea to land is generated by weather circulation cycle, which can be used for wind energy generation (bochlert, mcmurray, & tortorici, ). from the characteristics of sea land and island show that it is suitable to use the sustainable energy for seashore location. figure : pacific marine energy center model . smart home and green community green energy for each society is recommended to use as the power supply which can reduce the energy usage from main grid and the pollution from the main grid and society, respectively. therefore, many technologies have been used and involved for green society power generation, which can offer the green society concept and give as the following details. smart home based solar energy consumption smart home has become the interesting concept which can be used to serve the modern life requirements as shown in figure , where the solar, energy can be used as the electrical power supply and controlled by computing control system, in which the electricity usage quality and energy consumption cost balance can be controlled and managed. moreover, house can be monitored and controlled by using the computing system via internet connection, in which the energy saving and house security can be established by the same system, which is supplied by solar energy. meanwhile, house can be controlled by computer via internet to control on-off timer of every machine and lamp. for example, light and air condition can be switched on fifteen minute before arriving or off air conditioner fifteen minute after sleeping, which can make the most utilization on energy usage. r. rodprasert et al. / energy procedia ( ) – figure : smart home model supplied by solar energy lamp and non-lamp light distribution concept in modern society, electricity lamp is the one of necessary equipment that uses in every place, especially, on the street, where the safety environment is required. in order to reduce the cost with sustainable energy supply, solar energy is suitable for this requirement. the solar energy technology may not reduce the investment cost but it can reduce the maintenance cost and officer to use in the isolated area, which is hard to construct the wiring power system as shown in figure . the concept of new type solar cells can also offer the non-lamp light distribution as shown in figure (srithanachai, ueamanapong, niemcharoen, & yupapin, ), where in this case a thin film device can be operated and supplied by solar cell battery and give power distribution and use in any dark location, which can offer the low power consumption and good looking requirements. figure : street lamp using new type solar cells r. rodprasert et al. / energy procedia ( ) – figure : light distribution using thin film, which is supplied by solar cells for non-lamp light distribution concept wave energy to home wave energy is the absolute clean energy that uses wave power to produce the electricity. it can generate the electricity in both of surface and at the undersea by using the benefit of tidal water to generate the electricity via turbine as shown in figure . the surface wave energy can produce the electricity by construct the turbo-generator under the sea to generate the electricity from under water stream, while the buoyancy is used to keep the energy from wave surface. and all generated electricity will send to sea shore by using the underground electricity cable (bochlert, mcmurray, & tortorici, ; cada, ahlgrimm, bahleda, bigford, stavrakas, hall, moursund, & sale, ; frid, andonegi, depestele, judd, rihan, rogers & kenchington, ). figure : wave energy and cabling system however, both turbo-generator and floating device can give the sea environmental effects and the change in environments, which can give the change in ocean environment and sea life cycle. moreover, the installation instrument may be caused the travelling obstruction and accident. in figure , the other form of wave energy which is constructed near the sea shore by using benefit from tidal water. they can also be constructed in the electrical power dam location, which is located between river and sea or bottleneck places, and then the water from high tidal will move to low tidal by passing the power generator to generate the electricity. therefore, the tidal wave generator can generate the electricity based on rise-ebb tide, so it can produce the electricity all day (hammons, ). r. rodprasert et al. / energy procedia ( ) – figure : tidal wave generator new vehicle for transportation other energy generator is interested the hydrogen-cells engine that uses the hydrogen to generate the power. hydrogen can fine generally on earth, especially in water (h o), which is included two hydrogen molecules combined with an oxygen molecule per molecular structure. the hydrogen engine is as shown in figure . so, the water can be used as fuel for this kind of engine, the hydrogen molecule is separated from oxygen molecule, where the output of this process is oxygen. this idea seem to make benefit for the society because it can reduce the number cars which use fossil fuel, in which carbon monoxide (co) is the penetrated into the air, on the other hand, hydrogen-cell engine give the oxygen (o ) into the air (kahraman, ). in smart society, the business like rental electric vehicle(ev) battery station has been suggested to use because people can rent the battery for ev car and change them in anywhere, and can use power for solar and wind that can construct on every electrical lamp to charge the battery everywhere. figure : hydrogen engine system today, vehicle like car, train or airplane become an important parts of people life because it can help to save the travelling time. however, many organizations in many country have claimed that cued oil and natural gas are the limited resource that people can use for only next fifty years, and it make the air pollution. therefore, they claimed that people need to find other energy to use with any vehicle. they develop new type of energy not only the hybrid system but also the hydrogen-based system and magnetic-based power system (smeets, faaij, & lewandowski, ). the hybrid system is the combination between oil and electrical engine. in figure , the ev car charger is required to construct along the travelling routes. r. rodprasert et al. / energy procedia ( ) – figure : charger station for ev car community networks for information communication technology (ict) side, the cloud computing technology is needed to make the energy saving requirement. people in society can store their information on the server which provides by information technology’s provider. this server is provided the storage size and operating system for user. in figure , the link of communication system is provided by satellite and distributed to an office and a single house, where the solar energy is applied as an energy resource. figure : smart home link with central computing network for low energy consumption, it seem that people in society can gain the benefit by saving their cost to replace their personal computer and save cost to update the software, while they can use small case of computer such as zero desktop computer, which have only computer screen, mouse and keyboard while connect to its operating system (os) on the server via internet, to run the high performance program (madan, pant, kumar & arora, ). therefore, it can support every person in the society in order to reduce an investment cost for their gadget and extended write-off time for each technology. moreover, the research of e-world magazine ( ) claim that by use cloud technology in office can reduce the electricity cost because it provide the small computer which produce less heat to save the air condition power per hours (chard, caton, rana, & bubendorfer, ) . central diy in smart society, green technology needs to maintenance on schedule because it is the main energy system. however, some technologies need carefully maintenance and specially skill staff. so, the idea is constructed the central diy that stores the necessary mechanical tools for repairing purpose, especially, for solar cells or other r. rodprasert et al. / energy procedia ( ) – generators. the central diy is as shown in figure . in this case every household can request the service any time to avoid the bad situation such as solar cells cannot generate the electricity. moreover, the central diy center can reduce the expense cost of each household in the case of storing unnecessary tools, and support the urban people by increasing the repairing ability. figure : central diy at the village central cool room by using the underground location, we can construct the natural cooling power to keep their food cool, if the system is combined with the energy from another system, then it can help any people in community to save the usage power because cool from underground can reduce the energy per hours in order to use for cooling system. the samples of cooling locations are as shown in figures and . moreover, the underground central cooling room can reduce the electricity usage from refrigerator in each household, and improve the freezing time for each food materials, and it can also use as the cool warehouse to keep the agricultural products such as fruit and vegetable to extend the expiring time before transporting to the end users. figure : original cooling system in cold area r. rodprasert et al. / energy procedia ( ) – figure : central cool room self sufficient economy in green society, people can create the green agriculture product like non-season fruits by using benefit from green energy. they can produce green agricultural product in agricultural dome which people can control the temperature and water in that dome as shown in figure . it can help farmer to plant the products in any season. the energy resources such as solar and wind energy systems can give the electricity to agriculture dome by using computing control system. it shows the ability to support the people who live in far land area like snowy area to produce the food ingredient in the dome and uses the electricity from win generation system (oliveira & fernandes, ). therefore, this can expand the opportunity of farmer in order to produce more quality of food, while the risk on lose the food from outside environment such as weather and temperature can be reduced. figure : agriculture dome r. rodprasert et al. / energy procedia ( ) – figure : organic product self sufficient agriculture by using the green energy resources, we can produce the agricultural products in any time by using the agriculture dome, in which light and temperature can be controlled suitably. so, we can produce enough agricultural products to serve society demand and distribute to the other societies. therefore, the agriculture product quality can be improved and served to the society demand. finally, the large products will change the agricultural production cost, where the prize will drop down. so, customer can get required agriculture products as the lower cost to serve their requirements. in figures and , the organic product and green garden are required in city society because they can give fresh air and good health for the society. figure : green community public mind and religion based activities by using the clean energy farm, it can create many things that impact to the society, for instant, good intelligence, good health, good environment, which can be useful for sustainable living. the sustainable life cannot be completed if there is the public mind involved, therefore, the public mind is required to involve in the society. the route that can bring society to reach the public mind thinking is religion ways, which can keep society in peace, where finally, the sustainable living is succeed. the main benefit of clean energy is to reduce the money expense per month for each person or family, and reduce the electricity usage per hours for each household (bochlert, mcmurray, & tortorici, ). r. rodprasert et al. / energy procedia ( ) – . conclusion things in nature have shown the good candidate for world society, particularly, energy resources. green and sustainable energy resources in nature have been the good future energy for the world society, where they can be the permanent energies and have many advantages, especially, for environmental saving and better life. the power resources from solar, wind and wave have been the good things for green and sustainable power energy generators, which can be used to supply the society requirements with sustainable living. in addition, people morality is also important for sustainable living, in which the concept of self-efficient economy and agriculture, and religion based activities are also the good things, which they are required to include for sustainable living within the smart society. . acknowledgment the author would like to give the acknowledgement to king mongkut’s institute of technology ladkrabang (kmitl), bangkok, thailand for the laboratory facilities. . references bochlert, g..w., mcmurray, g.. r., & tortorici, c.e. ( ). ecological effect of wave energy in the pacific northwest. u.s. dept. commerce, united state, p. cada, g.., ahlgrimm, j., bahleda, m., bigford, t., stavrakas, d.s., hall, d., moursund, r., & sale, m. ( ). potential impact of hydrokinetic and wave energy conversion technologies on aquatic environment. fisheries, ( ), - chard, k., caton, s., rana, o., & bubendorfer, k. ( ). social cloud: cloud computing in social network. university of wellington, new zealand, - . dvorak, j.m., corcoran, a.b., ten, h. e.j., mclntyre, g.n., & jacobson, z.m. ( ). us east coast offshore wind energy resources and their relationship to peak-time electricity demand. wind energ, ( ), - frid, c., andonegi, e., depestele, j., judd, a., rihan, d., rogers, i. s., & kenchington, e. ( ). the environmental interaction of tidal and wave energy generation devices. impact assessment review, - hammons, t.j. ( ), tidal energy technologies: currents wave and offshore wind power in the united kingdom, europe and north america. renewable energy, - . kahraman, e. ( ). analysis of hydrogen fueled internal combustion engine. the graduate school of engineering and sciences of izmir institute of technology, ( ), - khunnam, w., yongram, n., sarapat, n., & yupapin, p.p. ( ). quantum matter generated by trapped particles. sciencejet, ( ), - . lovich, e. j., & ennen, r. j. ( ). assessing the state of knowledge of utility-scale wind energy development and operation on non-volant terrestrial and marine wildlife. applied energy, ( ), - madan, d., pant, a., kumar, s., & arora, a. ( ). e-learning based on cloud computing. international journal of advanced research in computer science and software engineering, ( ), - . oliveira, d. s. w., & fernandes, j.a. ( ). renewable energy: impact upon the environment, economy and society. multidisciplinary journals in science and technology, jrse, november edition, ( ), - . rio, d.p., & burguillo, m. ( ). assessing the impact of renewable energy deployment on local sustainability: towards a theoretical framework. renewable and sustainable energy reviews, ( ), - . smeets, e., faaij, a. & lewandowski i. ( ). the impact of sustainability criteria on the cost and potentials of bioenergy production. department of science, technology and society: utrecht university, netherlands, - . srithanachai, i., ueamanapong, s., niemcharoen, s. & yupapin, p.p. ( ). novel design of solar cells efficiency improvement using an embedded electron accelerator on-chip. optics express, ( ), - . zongrui, d., yuanxiong, g.., dapeng, w. & yuguang, f. ( ). market based scheme to integrate distributed wind energy. smart grid. ieee transaction on, ( ), - . characterization of south asian agricultural residues for potential utilization in future ‘energy mix’ - © published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of applied energy innovation institute doi: . /j.egypro. . . energy procedia ( ) – sciencedirect the th international conference on applied energy – icae characterization of south asian agricultural residues for potential utilization in future ‘energy mix’ muhammad danishac*, muhammad naqvib, usman farooqc, salman naqvid aschool of resource and environmental engineering east china university of science and technology, shanghai, china bdepartment of energy, building and environment, mälardalen university, västerås, sweden cdepartment of chemical engineering, faculty of engineering, university of gujrat, pakistan d centre for biofuel and biochemical research, department of chemical engineering, universiti teknologi petronas, malaysia abstract this paper characterizes various locally available agricultural residues in south asian region to evaluate their potential as feedstock for renewable energy production and contributing toward solving energy crisis and environmental issues. the thermo-chemical characterization has been performed in order to determine if the residues have potential to be used in biomass conversion technologies producing combined heat and power. the characterization methods for comparing different agricultural residues include proximate and ultimate analysis, heating value, ash content, thermo gravimetric analysis (tga) and structural composition analysis (sca). widely available agricultural wastes in south asian region were selected for the characterization i.e. bagasse, almond shell, corn cob, cotton stalks, wheat straw, sawdust, corn leaf, rice husk, rice straw, and corn straw. the analysis showed that the corn cob had the highest moisture content that will result in low energy efficiency of the thermal conversion technology due to energy requirement for drying. whereas almond shell had the lowest moisture content. ash and volatile contents were found to be highest in rice straw and almond shell respectively. the thermo gravimetric analysis showed that most of the agricultural residues can be easily decomposed and represent potential feedstock for biomass flexible combined heat and power systems through pyrolysis or gasification. © the authors. published by elsevier ltd. selection and/or peer-review under responsibility of icae keywords: agriculture residue, future energy, characterization, pyrolysis, gasification . introduction . . background south asian region (pakistan, india, bangladesh, and sri lanka) has one of the largest agriculture sector that plays a vital role in the region’s economy. [ , ] according to united nations environment programme (unep), a single district in south asia produces about . million tonnes of agriculture residues as wheat straw, rice straw, rice husk, bagasse, corn leaf, saw dust, cotton stalks etc. [ - ]. currently, the agriculture residues are utilized for domestic heating and as food for domestic cattle [ , ]. however, the energy content from the substantial amount of agriculture waste represents potential for bio-fuel or combined heat and power production [ , ]. in pakistan, about million people lives in remote areas/villages and around , villages are not provided with natural gas and electricity that are major energy requirements [ ]. since the agriculture waste is widely distributed and locally available, each district or village can produce its own electricity together with heat. in addition, the distributed electricity production can contribute towards reducing severe energy crisis in the country [ ]. most of the developed countries are utilizing all waste streams in the energy system as feedstock for renewable energy production [ , ]. however, south asian countries still lagging behind the right methodology and execution of biomass and agricultural residues as alternative renewable energy resource [ , ]. efficient utilization of biomass available online at www.sciencedirect.com © published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of applied energy innovation institute http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf muhammad danish et al. / energy procedia ( ) – and agricultural wastes to bio-energy can also contribute towards solving energy crisis and reducing complete dependency on fossil based resources [ , ]. . . objective of the study a number of thermo-chemical technologies, e.g. pyrolysis, gasification etc., are available to convert various agriculture residues to produce energy products [ , ]. for efficient utilization of the feedstock as renewable energy resource through thermal conversion methods requires detailed understanding of different properties of the locally available feedstock. this study characterizes widely available and distributed agriculture residues such as bagasse, cotton stalks, rice husk, corn cob, corn leaf, fruit shells, rice straw and corn straw that can be introduced in pyrolysis or gasification to produce flexible fuels like char, pyrolysis vapors, bio-oil or synthesis gas. the flexible fuels may then be utilized for combined heat and power production. the thermo-chemical characterization was performed and feedstocks are compared using proximate and ultimate analysis, heating values and thermo gravimetric analysis (tga). based on available residue properties, the efficient thermo-chemical conversion technology is identified for each resource. this research work will provide base for future studies on estimating potential biofuel or combined heat and power production at small scale that may be sufficient to meet local energy requirement of a single district or village. . methodology following sub-sections describes the characterization methods used to compare biomass properties of various available agriculture residues in south asia. . . agriculture residues agricultural residues such as bagasse, corn cob, corn leave, saw dust, almond shell, rice husk, cotton stalks, cotton straw, rice straw and wheat straw were used in the present study. it was estimated that production of these residues in south asia is metric tons [ ]. the residues are the left over products obtained after harvesting. most of the residue such as corn cob, corn leaves, saw dust, cotton straw and wheat straw were obtained from kabirwala district in pakistan. while almond shells and bagasse were collected from faisalabad and jhang districts. rice husk and rice straw were collected from gujranwala district. each residue was analyzed in triplicate for characterization and average results are reported. . . methods used for biomass analysis proximate analysis was performed to determine fixed carbon, ash content, volatile content, and moisture content present in the desired amount of agriculture residue sample [ ]. the standard test method for proximate analysis used i.e. d- astm [ ]. the moisture content was estimated by the weight loss of the biomass sample as a result of heating the sample at oc in a drying oven. to estimate the volatile contents, the weight loss was recorded after placing the sample in muffle furnace at oc for minutes. ash contents were calculated by the residue left after heating the sample at oc until the constant weight was achieved [ ]. the elemental composition of the agriculture residues were determined through ultimate analysis of samples [ ]. leco chn- analyzer was used to estimate the carbon, hydrogen and nitrogen contents of the dried agriculture residue samples. to estimate the sulfur content, leco sulfur analyzer sc was used as per astm standards. it is significantly important to estimate the lignin, cellulose, and hemi-cellulose contents together with extractives for reliable characterization of biomass. different techniques can be used for structural analysis based on qualitative and quantitative methods [ ]. the structural analysis is done by using magnetic resonance techniques, as this technique has been proved to be most efficient analytical tool. more extraction was also done by using an acid detergent solution, containing % sulfuric acid solution. a large number of extraction processes are recommended for the hemicellulose, cellulose and lignin content [ ]. the calorific values of the agriculture residue samples were determined by bomb calorimeters and also using empirical relationship obtained from the literature [ ]. astm d was used as standard analytical method to determine calorific values of biomass samples [ ]. the empirical relation used for the determination of high heating values are extracted from basic analysis data, i.e. ultimate analysis, proximate analysis and structural analysis for the specific sample of the biomass. the formula according to the composition of elements is as follow: muhammad danish et al. / energy procedia ( ) – higher heating value dry (mj/kg) = . c + . h + . s − . o − . n − . ash [ ]. where c, n, s, h and o are the weight percentages of carbon, nitrogen, sulphur, hydrogen and oxygen on dry basis respectively. . . thermo-gravimetric analysis (tga) leco tga- thermo-gravimetric analyzer was used in selectable atmosphere of n . the analyzer determine the weight loss as function of varying temperature in selectable atmosphere. the temperature used for the tga start slowly from oc at an incremental rate of oc/min till the final temperature of oc. . results and discussion the proximate and ultimate analysis of the agriculture residue samples are reported in table and table . each estimated property is discussed in following sub-sections. . . moisture content the moisture content plays a vital role in the selection of efficient thermal conversion technology. the biomass containing high moisture content represents significantly low new energy density by mass due to the mass of water. this results in utilization of energy-intensive drying operation to reduce the moisture content and to be able to operate conversion technology [ ]. for efficient performance of the thermal conversion technology, gasification or pyrolysis, the biomass shall not represent more than - % of moisture content. biomass resources with higher moisture contents can be converted through bio-chemical processes such as anaerobic digestion for biogas production. the estimated moisture content in the obtained agriculture residue samples ranges between about . %wt. (almond shell) and about . %wt. (corn cob). it is important to note that the estimated moisture contents of available agriculture residues showed slightly different results for most of the agriculture residues when compared to values reported in the literature data previously published [ - ]. the marginal differences in reported values are mainly due to agriculture residues obtained from different locations, climate differences. in addition, the handling and storage also contributes towards moisture content. table proximate analysis of selected agricultural residues (% wt. as dry) samples moisture contents volatile matter ash contents fix carbon wheat straw . . . . rice husk . . . . corn cob . . . . corn leaf . . . . saw dust . . . . bagasse . . . . cotton stalks . . . . corn straw . . . . rice straw . . . . almond shell . . . . muhammad danish et al. / energy procedia ( ) – table ultimate analysis of selected agricultural residues (% wt. as dry) sr. no samples carbon hydrogen nitrogen sulphur oxygen hhv(mj/kg) saw dust . . . . . . bagasse . . . . . . corn cob . . . . . . rice husk . . . . . . wheat straw . . . . . . cotton stalks . . . . . . corn leaf . . . . . . corn straw . . . . . . rice straw . . . . . . almond shell . . . . . . . . volatile and ash contents the volatile contents of the agriculture waste samples were determined on dry basis. the lowest volatile content was found in the rice husk i.e. %wt. and the highest volatile content in the almond shell i.e. . %wt. the results regarding the ash contents determined in the study are considerably different from the data of literature due to the agriculture residues available in different regions and climate conditions. the samples of wheat straw, corn leaf, saw dust, almond shell, cotton stalks and corn straws had low ash contents that were less than % wt. the sugarcane bagasse and corn cob had medium ash contents that were less than % wt. among the selected biomass samples, rice straw and rice husk had substantially higher ash content i.e. greater than % wt. soil pollution (decay) is different for every biomass sample taken due to the difference origin of sources of samples. it is beneficial from another perspective that the inorganic compounds present in the agriculture waste resources with higher ash contents have potential to be used as catalysts in the thermal conversion technologies e.g. gasification and pyrolysis [ ]. . . elemental composition and heating values the calorific values of the samples are reported in the ultimate analysis (see table ). the heating/calorific values of the agriculture waste samples determined by bomb calorimeter showed nearly identical values as reported in the literature. cotton stalks and saw dust showed the highest higher heating values (hhv) i.e. about mj/kg. whereas, rice straw showed the lowest hhv among the available sample i.e. about mj/kg. the considerable heating values of the agriculture waste samples showed that these locally available renewable resources can potentially be converted to substantial amount of bio-energy products from effective conversion technologies. from the elemental composition perspective, sulfur and nitrogen were found to be in small amounts in all samples except corn straw that has highest nitrogen and rice straw that has highest sulfur content. . . chemical characterization chemical characterization of the agriculture residues will provide useful information for modeling of thermal conversion processes. hemicellulose and cellulose contents present in agro-waste samples were found to be less than %wt. almond shell samples has highest cellulose content and corn leaf with the lowest cellulose content. the highest hemi-cellulose content was found in the corn cob samples. corn cob and cotton stalk samples represented lower lignin content, i.e. about %wt. and % wt. respectively. since the biomass with low lignin contents are suitable for bio-oil production from pyrolysis, corn cob and cotton stalk will be interesting option to be utilized in pyrolysis as compared to other selected samples. whereas, rice husk and wheat straw samples could be gasified due to higher lignin content, i.e. about % wt. lignin content. muhammad danish et al. / energy procedia ( ) – table : structural analysis of agriculture waste samples (dry and free ash basis) sr. no samples cellulose hemicellulose lignin extractives saw dust . . . . bagasse . . . . corn cob . . . . rice husk . . . . wheat straw . . . . cotton stalks . . . . corn leaf . . . . corn straw . . . . rice straw . . . . almond shell . . . . . . thermal gravimetric analysis (tga) the thermal gravimetric analysis was used to study and analyze the degradation of selected samples. the tga curves are shown in figure . tga combustion and pyrolysis techniques were adopted to found the molecular deterioration characteristics. tga curves from - show that almost - % of the weight of samples has been decomposed before °c. major portion of the weight of the sample was decomposed in between - oc. the tga curves are the best option to determine the optimum temperature for the gasification or pyrolysis reactions [ ]. easy decomposition of all the waste samples during thermal decomposition shows that these samples would be ideal feedstocks in combustion processes [ ]. the tga curves indicates the optimum temperatures of the each of the biomass samples corresponding to their loss in weight .sawdust, cotton stalks, sugarcane bagasse, corn cobs and corn leaf have temperature range, ranging from oc to oc. the least value of the weight loss of the biomass samples is for corn leaf, i.e. %, while bagasse and almond shell indicate highest weight loss, i.e. %, at pyrolysis temperatures. figure thermo-gravimetric analysis curves of selected agriculture wastes muhammad danish et al. / energy procedia ( ) – . conclusions the study were conducted to determine the thermochemical properties of available agriculture residues in south asian region to identify their potential to be used in thermal conversion processes for biofuel, heat or power production. the agriculture residues included bagasse, almond shell, corn cob, cotton stalks, wheat straw, sawdust, corn leaf, rice husk, rice straw, and corn straw. the estimated moisture contents of available agriculture residues showed slightly different results for most of the agriculture residues when compared to values reported in the literature. the marginal difference in reported values is mainly due to agriculture residues obtained from different locations, climate differences, handling and storage. the lowest volatile content was found in the rice husk i.e. %wt. and the highest volatile content in the almond shell i.e. . %wt. rice straw and rice husk had substantially higher ash content i.e. greater than % wt. cotton stalks and saw dust showed the highest higher heating values (hhv) i.e. about mj/kg. based on available biomass in south asia region, calculated amount of energy is , , , mj annually which can at least contribute to the basic needs of the countries. hemicellulose and cellulose contents present in agro-waste samples were found to be less than %wt. from the elemental composition perspective, sulfur and nitrogen were in small amounts in all samples except corn straw that has highest nitrogen and rice straw that has highest sulfur content. tga curves show that almost - % of the weight of samples has been decomposed before °c. major portion of the weight of the sample was decomposed in between - oc acknowledgements this work has been supported by chemical engineering department at uog. one of the authors would like to thank kks-stiftelsen and industrial partners of future energy profile at mdh. references [ ] joshi, pramod k., et al. 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[ ] electricity generation from agricultural residues in five south asian countries: prospects and potential md. mizanur rahman and jukka v. paatero department of energy technology, school of engineering, aalto university, finland. th international conference on sustainable energy and environment (see ): a paradigm shift to low carbon society - february , bangkok, thailand. biography i did my b.sc chemical engg. from university of the punjab, lahore in & m.sc chemical engg. from u.e.t lahore,pakistan in .then i joined as a lecturer in department of chemical engg.university of gujrat.currently i am phd scholar in east china university of science and technology, shanghai, china wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ oxygen sensing and integrative stress signaling in plants [open] update on integrative oxygen sensing and signaling oxygen sensing and integrative stress signaling in plants [open] romy r. schmidt, daan a. weits, claudio f. j. feulner, and joost t. van dongen rwth aachen university, institute of biology i, worringerweg , aachen, germany orcid ids: - - - (r.r.s.); - - - (d.a.w.); - - - (j.t.v.d.). plants grow in a dynamic environment and continu- ously face numerous stress conditions in parallel. this fluctuating environment pushed the evolution of exten- sive metabolic flexibility (sweetlove et al., ; van dongen et al., ). flooding is an example of an envi- ronmental condition that combines many different stress factors simultaneously, including limited gas diffusion (e.g. of oxygen, carbon dioxide, and ethylene), tempera- ture stress, light quality and quantity, and osmotic and oxidative stress. changes in the internal concentration of oxygen, but also e.g. ethylene, are crucial early signals for the initiation of adaptation strategies to flooding (sasidharan and voesenek, ; sasidharan et al., ). initially, a plant cell responds to nearly all these different types of stresses by using the same set of second mes- sengers (such as reactive oxygen species [ros], calcium, nitric oxide [no], and lipid molecules) and by activating signaling cascades through kinases (bjornson et al., ; zhu, ). this raises the question of how cells detect and differentiate between stresses. one fundamental aim in low-oxygen research is to unravel how organisms detect and react to the lack of oxygen and respond to an impairment of their energy metabolism (ratcliffe, ). in both plants (licausi et al., a; gibbs et al., , ; weits et al., ; white et al., ) and animals (loenarz and scho- field, ; ratcliffe, ; bishop and ratcliffe ; hamanaka et al., ), key transcriptional regulators have been identified that regulate the hypoxic re- sponse via the integration of cellular signals that are required for their activation (box ). here, we discuss the nature and origin of these various signals under hypoxia that initiate adaptation responses at the transcriptional and (post-) translational level and their potential integration points. in addition, we postulate that it is the integration of different signal inputs that defines a response specific to oxygen limitation. fur- ther, we will discuss the state of current methods and technologies to measure plant internal oxygen con- centrations. the concept of an integrative oxygen sensing mechanism abiotic stress perception appears not to rely on the de- tection of only one specific effector or ligand. despite all efforts to reveal the primary sensors for diverse abiotic stresses, unequivocal identification remains arduous (zhu, ). in arabidopsis (arabidopsis thaliana), the n-end rule pathway of targeted proteolysis was shown to act as a mechanism that controls protein levels of subgroup vii ethylene-response factor (erfvii) transcription factors by regulating their protein turnover in an oxygen- concentration-dependent manner (gibbs et al., ; licausi et al., a; box ). remarkably, protein abun- dance of related to apetala . (rap . ), an erfvii member in arabidopsis, is also positively regu- lated by hydraulic conductivity of root the research on abiotic stress responses in the van dongen lab- oratory is financed by rwth aachen university and the german science foundation. address correspondence to dongen@bio .rwth-aachen.de. the author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy de- scribed in the instructions for authors (www.plantphysiol.org) is: joost t. van dongen (dongen@bio .rwth-aachen.de). all authors contributed to conceiving and writing the manuscript. [open] articles can be viewed without a subscription. www.plantphysiol.org/cgi/doi/ . /pp. . plant physiology�, february , vol. , pp. – , www.plantphysiol.org � american society of plant biologists. all rights reserved. https://plantphysiol.orgdownloaded on april , . - published by copyright (c) american society of plant biologists. all rights reserved. http://orcid.org/ - - - http://orcid.org/ - - - http://orcid.org/ - - - http://orcid.org/ - - - http://orcid.org/ - - - http://orcid.org/ - - - http://orcid.org/ - - - http://orcid.org/ - - - http://orcid.org/ - - - http://crossmark.crossref.org/dialog/?doi= . /pp. . &domain=pdf&date_stamp= - - mailto:dongen@bio .rwth-aachen.de http://www.plantphysiol.org mailto:dongen@bio .rwth-aachen.de http://www.plantphysiol.org/cgi/doi/ . /pp. . https://plantphysiol.org (hcr ), a raf-like mapkkk, which could phosphorylate rap . in vitro. this n-end rule-independent stabiliza- tion mechanism is proposed to allow the integration of cation (specifically potassium) availability with the oxygen concentration in the soil (shahzad et al., ). low-oxygen stress impairs diverse plant cellular func- tions, including those in the cytosol, nucleus, mitochon- dria, and endoplasmic reticulum (er). actually, molecular oxygen is among the most-utilized molecules in eukary- otic cellular metabolism (raymond and segrè, ) with more than oxygen-dependent reactions. thus, de- creasing oxygen levels might be indirectly sensed due to an impairment of various metabolic pathways when the cellular oxygen concentration changes around or below the michaelis-menten constant km for oxygen of the en- zymes involved. as such, any oxygen-dependent enzyme has the potential to act as a kind of sensor, suggesting si- multaneous oxygen sensing at multiple sites of the cell. then again, it might well be that one or a few oxygen- concentration-dependent enzymes evolved to primarily monitor aerobic metabolism. taken together, three scenarios of cellular oxygen sensing can be discussed: ( ) decentralized sensing at many sites of the cell by e.g. oxygen-consuming en- zymes, ( ) a primary “oxygen sensor” detects a drop in oxygen to initiate all signaling cascades, and ( ) a combination of scenario and . a primary oxygen sensor (scenario ) would detect the cellular oxygen concentration but not the oxygen availability. however, differentiation between “concentration” and “availabil- ity” is important, since a low oxygen concentration can result in a high flux of oxygen into the tissue and does not necessarily lead to low-oxygen stress. the advantage of a decentralized oxygen-sensing mechanism (scenario ) would be that it allows for fine-tuning the response to low-oxygen conditions to a particular situation. by adding up various oxygen-concentration-related signals, such integrative signaling would trigger hypoxic re- sponses only when the actual oxygen concentration does indeed disturb cellular homeostasis. the decentralized oxygen-sensing model further suggests that perturba- tions of processes in various organelles, at the plasma membrane and in the cytosol can initiate low-oxygen- stress signaling and that these various triggers must be integrated to activate appropriate transcriptional reprogramming and cellular adaptation responses. a specific balance between multiple stress-induced sig- nals could provide a mechanism—like a “cellular fin- gerprint”—to discriminate between different stress types. in this review, we summarize signaling pathways from different cellular compartments that are initiated by low-oxygen stress and discuss potential integration points for the multiple signal inputs resulting in hypoxia-specific adaptive responses. n-end rule pathway in arabidopsis, members of the erfvii transcription factor family (box ) contain a conserved n-terminal domain that makes them oxygen- and no-dependent substrates of the n-end rule pathway of targeted pro- teolysis (gibbs et al., ). plant physiol. vol. , schmidt et al. https://plantphysiol.orgdownloaded on april , . - published by copyright (c) american society of plant biologists. all rights reserved. https://plantphysiol.org while the n-end rule is acting as a safeguard mecha- nism to limit erfvii abundance under aerobic condi- tions, several observations suggest that its control is limited to certain met-cys proteins, environmental con- ditions, and developmental phases of the plant. arabi- dopsis n-end rule mutant seedlings show constitutive expression of about half of the core hypoxia-responsive genes (gibbs et al., ), indicating that the other hypoxia genes are not controlled by this pathway. in addition, introduction of a gus reporter driven by the alcohol dehydrogenase (adh ) promoter in arabidopsis wild-type seedlings or a proteolysis (prt ) mutant defec- tive in erfvii turnover revealed constitutive activation of the promoter in certain tissues of the prt mutant, but not in all as compared to the wild-type. interestingly, in both the wild-type and the prt mutant an increased gus signal was observed after h of hypoxia (gibbs et al., ). thus, in n-end rule mutants, the hypoxic response is not entirely saturated, nor do mutations in this pathway affect all plant tissues in a similar manner. while consti- tutive expression of a subset of hypoxic genes is observed in n-end rule mutant seedlings, a recent report revealed that this constitutive expression is less pronounced in adult mutant plants (giuntoli et al., ). as submer- gence of rosette-stage plants just prior to bolting still re- sults in the activation of hypoxic genes, it strongly argues for additional, n-end rule-independent mechanisms that control either erfvii activity or alternative transcrip- tional cascades. in addition, at least one erfvii, sub- mergence a (sub a) from rice (oryza sativa), is not a target of the n-end rule pathway, although it possesses the n-terminal consensus sequence as found in arabi- dopsis erfviis (gibbs et al., ). this further suggests alternative regulatory pathways. mitochondrial dysfunction as trigger for hypoxia signaling limited oxygen availability affects respiration, which impacts on a whole palette of mitochondrial parameters and processes (see box ), including reactive oxygen and nitrogen species (ros/rns) homeostasis, redox status of nad(p)h and antioxidant pools, atp/adp ratio, the proton-motive force, and calcium and metabolite levels, which in principle could all trigger mitochondrial sig- naling (schwarzländer and finkemeier, ). indeed, roles for these diverse signals in mitochondrial retro- grade responses have been established and are discussed by wagner et al. ( ) in this focus issue. the role of mitochondrial retrograde signals in hypoxia has been partly investigated; for example, mitochondrial ros signals were shown to impact on anoxia tolerance (chang et al., ). likewise, in animals, mitochondrial electron transport chain (metc)-derived ros signals appear to provoke adaptation responses upon hypoxia (hamanaka et al., ). interestingly, complex iii inhi- bition under aerobic conditions by antimycin-a treat- ment in part causes induction of hypoxia-responsive genes in arabidopsis (ng et al., a), which could be due to disruption of the atp/adp ratio and/or in- creased mitochondrial ros production. furthermore, metabolic signals derived from mitochondria might be integrated into cellular reprogramming during hypoxia. this is supported by the notion that overexpression of the mitochondrial uncoupling protein (ucp ), which decreases stress-induced ros production, results in a hypoxic metabolic pattern and transcriptomic sig- nature (barreto et al., ). ucp proteins in animals have been linked to the induction of hypoxic responses (dromparis et al., ), suggesting a universal role of this protein family in controlling low-oxygen responses. an important feature of plant mitochondria is that the proton-translocating complexes i, iii, and iv (see box ) are capable of forming so-called supercomplexes (dudkina et al., ). remarkably, mitochondrial supercomplex assembly is oxygen dependent, as in potato tubers, low oxygen promotes dissociation of complex i from the supercomplex, while reassembly is observed under reoxygenation (ramírez-aguilar et al., ). supplying isolated mitochondria with m m m plant physiol. vol. , integrative oxygen sensing and signaling in plants https://plantphysiol.orgdownloaded on april , . - published by copyright (c) american society of plant biologists. all rights reserved. https://plantphysiol.org succinate under a low ph also caused dissociation of complex i as observed for low-oxygen conditions. substrate-dependent supercomplex formation was also found in mouse cells, in which the plasticity of the metc complexes appears to be used to fine-tune res- piration (lapuente-brun et al., ). that said, it still needs to be demonstrated that supercomplex formation also affects respiration rates in plant mitochondria. taken together, the release of complex i from the supercomplex does not appear to be the initial trigger for hypoxic responses in plants but is already part of the adaptation response that is initiated by a drop in ph and a change in substrate availability. when the oxygen concentration is reduced below a certain threshold, respiration is impaired (nikoloski and van dongen ). however, it remains to be deter- mined at what subcellular oxygen concentration mito- chondrial dysfunction is initiated. precise determination of the mitochondrial oxygen concentration is especially important, as the affinity for oxygen of cytochrome c oxidase likely depends on cellular conditions such as ph, redox status, and oxygen concentration (krab et al., ). also, it is to be determined whether this respira- tory impairment is specific to hypoxia or if other abiotic stresses cause similar mitochondrial constraints, too. ucps, type ii nad(p)h dehydrogenases, and alternative oxidase (aox) as part of the mito- chondrial energy dissipation pathways (see box ; maxwell et al., ; geisler et al., ; millar et al., ) have roles in the response to diverse abiotic and biotic stresses, which in general cause an energy crisis (pu et al., ; zhu, ). beyond that, mitochondrial ros production with signaling function can be observed under salt or drought stress (hernandez et al., ; pastore et al., ), indicating that stress signals released upon mitochondrial dysfunction are not hypoxia specific per se. a fundamental biological question that needs further attention is how cells distinguish between hypoxia-induced mitochondrial signals and those in- duced by other stresses. the er as signaling hub protein folding in the er is essential for the stability and functionality of many secreted and membrane- bound proteins. although the er employs different proteins and pathways for this task, it is inevitable that some proteins get misfolded especially during stress (hegde and ploegh, ). er stress results in the acti- vation of the unfolded protein response, which en- hances the function of the protein folding machinery and the protein quality control system, see liu and howell ( ) for a detailed overview. the major pathway for oxidative protein folding is present in the er and relies on protein disulfide isomerase (pdi) and er thiol oxidase (ero) proteins (aller and meyer; ). pdi oxidizes proteins and is regenerated by ero through the transfer of electrons from pdi to molecular oxygen. the km of the ero protein from yeast was found to be – mm for oxygen, which is similar to that of aox in plants (gross et al., ). if plant ero proteins display a similar km as their yeast counterpart for oxygen, then they would be functionally impaired under hypoxia and might act as sensors for low-oxygen conditions. interestingly, only the disulfide bond for- mation during the folding phase in the er involving eros was shown to be oxygen dependent in mamma- lian cells, while subsequent glycosylation, er export, golgi processing, and transit to the extracellular space were not (koritzinsky et al., ). as oxygen-dependent folding is directly impaired upon low-oxygen stress, it has been suggested that the er constitutes a cellular oxygen sensor in animals that contributes to signaling and survival during hypoxic conditions (wouters and koritzinsky, ). future work is required to under- stand if this putative er pathway also plays a role in plants. of note, in mitochondria, oxidative protein folding relies on a flavin adenine dinucleotide (fad)- dependent thiol oxidase that acts in an oxygen- dependent manner (ang et al., ), suggesting that other protein folding pathways might have a role in low- oxygen stress. interestingly, the er also represents an important crossroad for mitochondrial stress signals. disturbance of mitochondrial function results in a signal to the nu- cleus, the so-called mitochondrial retrograde regulation (mrr; rhoads and subbaiah ). mrr relies on both ros and calcium signals, and recently, several of the protein components of the pathway were uncov- ered. transmembrane-domain-containing no apical meristem/arabidopsis transcription ac- tivation factor/cup-shaped cotyledon (nac) transcription factors were found to act as im- portant modulators of the transcriptional response during mrr (de clercq et al., ; ng et al., b). both anac and anac mediate mrr re- sponses but are located at the er, indicating that mi- tochondrial signals are received at the er. in this case, the mitochondrial signal is proposed to activate a yet- unknown protease that releases the nac transcription factors from the er membrane, which subsequently travel to the nucleus to modulate expression. many of the mrr-induced genes are also hypoxia respon- sive, including the erfvii transcription factor gene hypoxia responsive erf , (hre ), encoding a regulator of anaerobic responses in arabidopsis (licausi et al., ). therefore, it would be worthwhile to analyze the contribution of er-mediated mrr to low-oxygen tolerance in plants. energy signaling the harmful character of low-oxygen stress lies in its impact on oxidative phosphorylation in the mitochon- drion, which delivers energy equivalents in the form of atp (millar et al., ). however, a low local oxygen concentration does not necessarily lead to an energy crisis when the flux of oxygen toward the mitochondria can keep pace with respiratory oxygen consumption. plant physiol. vol. , schmidt et al. https://plantphysiol.orgdownloaded on april , . - published by copyright (c) american society of plant biologists. all rights reserved. https://plantphysiol.org therefore, it is of importance that any changes in the atp-producing processes within mitochondria are communicated to other compartments to induce ap- propriate adaptive responses. by doing so, differentia- tion is required between ( ) an energy crisis that is induced by mitochondrial dysfunction due to hypoxia, and ( ) a low-energy status that is caused by high atp consumption due to metabolic activity. only sensing cellular oxygen levels without taking into account the actual energy charge of the cell could provoke cost- intensive adaptation responses in tissues with high respiratory activity. for detailed discussion of mito- chondrial energy signaling, we would like to refer to the update of wagner et al. ( ) in this focus issue. eukaryotic energy sensing is largely conserved and involves the two kinases suc nonfermenting -related kinase (snrk ) and target of rapamycin (tor) in both plants and animals (broeckx et al., ). plant snrk is activated in response to energy-depleting stress condi- tions to promote plant survival. loss of snrk function impairs submergence tolerance in plants (cho et al., ). it is important to note that snrk appears to sense the amp/atp ratio and adp/atp ratio in cells, linking its activation directly to an energy crisis (hardie, ). many different stresses can cause an energy crisis; not surprisingly, most of the core anaer- obic genes are not hypoxia specific (van dongen and licausi, ). stresses that provoke a cellular “energy crisis” evoke translational repression, which has also been observed during hypoxia (branco-price et al., ; mustroph et al., ). in eukaryotic cells, growth in response to energy availability is in part controlled by the tor protein kinase (dobrenel et al., ). tor controls translation initiation and has been shown to be inacti- vated in mammalian cells upon hypoxia (wouters and koritzinsky, ). in plants, a picture has emerged in which tor kinase is active under favorable energy conditions, while snrk is stimulated upon energy limitation (tomé et al., ). moreover, tor and snrk appear to act antagonistically. so far, the func- tion of snrk under low-oxygen conditions in plants is well established; however, a role for tor is still un- explored. ros signaling cellular imbalances as a result of abiotic stress cause a change in ros homeostasis. in addition, during initial stress exposure, a so-called oxidative burst is observed, which acts as a signal to initiate adaptive responses (schippers and schmidt, ). although counterintui- tive, mitochondrial ros function in retrograde signaling during oxygen deprivation to adjust energy management in yeast and animal cells (guzy et al., ; hamanaka et al., ). also in plants, a mitochondrial ros burst is observed upon a drop in oxygen levels (chang et al., ). as application of antimycin-a mimics this burst, it is suggested that superoxide (o ) derived from complex iii might act as a signaling molecule during mitochondrial dysfunction upon oxygen deprivation. in order to prevent the build-up of high levels of superoxide, mitochon- dria actively scavenge it by employing mangenese superoxide dismutase (mnsod). the hydrogen peroxide (h o ) produced during this reaction either oxi- dizes mitochondrial proteins or exits the organelle to induce downstream signaling responses. to exit mitochondria, h o would rely on aquaporins (bienert et al., ). within the cytosol, ros as signaling molecules are rather short lived due to the high cytosolic antioxi- dant capacity. moreover, to provide mitochondrial specificity to the ros signal, sensing and translation of this signal is expected to occur near the mito- chondrial surface. so far, release of h o by mito- chondria during oxygen deprivation into the cytosol has been linked to the activation of mitogen- activated protein kinase (mpk ) and mpk in arabidopsis (chang et al., ). the fact that these mpks are involved in a broad range of bi- otic and abiotic stress pathways (rodriguez et al., ) implies that they are integrated into local sen- sory complexes to maintain ros-source information to activate stress-specific responses. as loss-of- function mutants of either mpk or mpk do not largely affect the activation of anaerobic genes (chang et al., ), additional components in the mitochondrial ros-signaling pathway related to low- oxygen stress await to be uncovered. here, it is of in- terest to note that mitochondria are often in direct contact with the er (mueller and reski, ), which therefore might be involved in relaying or translating the mitochondrial ros signal. next to the transient mitochondrial oxidative burst upon oxygen deprivation, a plasma membrane-localized burst occurs through activation of calcium-dependent nadph oxidases (blokhina et al., ; baxter-burrell, ). as respiratory burst oxidase homo- log (rboh)-dependent ros production occurs during nearly every stress, it remains unclear how such signals can be rendered specific for low-oxygen stress. arabidopsis contains nadph oxidases, called rbohs, of which three—rbohd, rbohf, and rbohi—have been implicated in low-oxygen re- sponses (pucciariello et al., ; liu et al., ; lin et al., ). although fermentative genes including adh have been shown to depend on single rboh activity, the exact mechanism through which each rboh contributes to low-oxygen signaling needs fur- ther investigation. recently, rbohi activity providing submergence tolerance could be linked to auxin sig- naling (lin et al., ). nadph oxidases are activated by rho-like small g-protein of plants (rop) and calcium-dependent kinases (baxter-burrell et al., ; suzuki et al., ). rop promotes the oxidative burst during oxygen deprivation by activating nadph oxidases. the burst is transient, as h o activates rop gtpase activating protein (ropgap ), which deactivates rop signaling (baxter-burrell et al., ). plants lacking ropgap show impaired low-oxygen plant physiol. vol. , integrative oxygen sensing and signaling in plants https://plantphysiol.orgdownloaded on april , . - published by copyright (c) american society of plant biologists. all rights reserved. https://plantphysiol.org tolerance. recently, it was found that the erfvii tran- scription factor rap . activates the expression of hypoxia responsive universal stress pro- tein (hru ), which, like ropgap , acts to dampen nadph oxidase activity (gonzali et al., ). poten- tially, ropgap and hru not only limit the length of the initial apoplastic ros burst but might be involved in protecting the plants from an oxidative burst upon reoxygenation. studies on mammalian cells suggest a feed-forward loop between the mitochondrial ros burst and the activation of nadph oxidases (kröller-schön et al., ). so far, this concept has not been studied in plant cells, but it would be intriguing to be investigated further. calcium signaling nadph oxidase-driven ros production depends on calcium, while ros in turn can modulate calcium up- take into the cytosol (mazars et al., ; suzuki et al., ), which lets both second messengers be part of a tightly linked signaling cross-talk. stress induces an increase in cytoplasmic calcium levels, which activates diverse calcium-binding proteins that decode the cal- cium signal into a cellular and transcriptional response (dodd et al., ). among these calcium-activated proteins are kinases, enzymes, and transcription fac- tors. the increase in cytosolic calcium levels occurs through the release of calcium from the apoplast and/ or cellular organelles (edel et al., ). early anoxia studies revealed a rise in cytosolic cal- cium levels by using an aequorin-based reporter in arabidopsis (sedbrook et al., ). upon oxygen deprivation, a biphasic calcium response was observed, with a first initial short-lived calcium spike occurring within minutes of anoxia, followed by a second, pro- longed calcium response that lasted several hours. in addition, the authors showed that inhibition of calcium fluxes by calcium channel blockers resulted in a partial inhibition of adh expression under anoxia. also in maize, the use of such blockers impairs the expression of adh under low-oxygen stress (subbaiah et al., ). still, the extent to which calcium fluxes and sig- naling events influence anaerobic gene expression is largely unexplored in plants. cytosolic calcium homeostasis is rapidly restored after a calcium spike by active transport mechanisms (sanders et al., ). in plants, energization relies ei- ther on calcium pumps powered by atp hydrolysis or by ca +/h+ antiporters powered by a proton-motive force (dodd et al., ). the energy-consuming trans- port of calcium is essential to obtain the basal levels, against which calcium release channels operate tran- siently to elevate free cytosolic calcium levels upon a stress stimulus. thus, after the cytosolic calcium spike, prestress levels need to be restored to keep the system sensitive toward a follow-up transient increase in calcium (bose et al., ). these properties suggest that calcium signaling might be restricted to the ini- tial phase of low-oxygen stress, as increasing atp constrains and the ph change under prolonged stress conditions might impair calcium homeostasis mechanisms. the origin of calcium released into the cytosol under low-oxygen stress in plants is partly explored. both plasma membrane calcium channel blockers as well as intracellular calcium channel blockers in part block calcium-dependent hypoxic responses (sedbrook et al., ; yemelyanov et al., ). potential intracellular calcium sources for the cytosolic spike during oxygen deprivation might be the vacuole, the er, and mito- chondria. although roles for er and mitochondria in cytosolic calcium release have been described in mammalian cells (rizzuto et al., ; wiel et al., ), it is still unclear to which extent these organelles con- tribute to calcium signaling under abiotic stresses in plants. in rice, calcineurin b-like interacting protein kinase (oscipk ) has been shown to be required for the expression of genes encoding gly- colytic enzymes, including adh (lee et al., ; meyer et al., ). excitingly, oscipk is activated by snrk , linking it to the energy-sensing network. en- ergy saving as an adaptation response to low-oxygen stress can be achieved by controlled selective transla- tion of mrna (sorenson and bailey-serres, ), a process that is regulated in a calcium-dependent man- ner. calmodulin (cml ) from arabidopsis acts as a potential calcium sensor that colocalizes under low-oxygen stress to mrna ribonucleoprotein parti- cles,. including stress granules. the latter are formed under hypoxia to serve as storage of translationally inhibited mrna (lokdarshi et al., ). taken together, despite the unquestionably eminent role of calcium in the initial response to low-oxygen stress, major gaps exist regarding the regulation of calcium fluxes, homeostasis, and the role of specific calcium sensor and signaling proteins in adaptation to hypoxia. measuring oxygen concentrations in plants a major bottleneck for the research on low-oxygen stress is that accurate measurements of in situ oxygen concentrations in plants are difficult. tools and methods to resolve the dynamic variation in oxygen levels with spatial and temporal resolution are needed for a better understanding of low-oxygen signaling at the cellular level. over the years, numerous methods for accurate measurement of oxygen have been developed (box ). invasive oxygen measurements using clark-type oxy- gen electrodes and optical oxygen sensors are commonly used and led to our current understanding on the dy- namics and distribution of oxygen in plants. still, the development of noninvasive oxygen measurement methods in plants is largely lacking behind as compared plant physiol. vol. , schmidt et al. https://plantphysiol.orgdownloaded on april , . - published by copyright (c) american society of plant biologists. all rights reserved. https://plantphysiol.org to the mammalian field, were cancer research has driven the development of a broad range of methods for the detection of hypoxia within animal tissue, such as solu- ble oxygen sensitive fluorescent dyes, genetically enco- ded sensors, positron emission tomography (pet), and f nmr (nmr) (zhang et al., ; dmitriev and papkovsky, ; fleming et al., ). clark-type electrodes are based on the diffusion of oxygen through a membrane to the oxygen-reducing cathode, which generates a current that is proportional to the oxygen concentration (clark et al., ). a dis- advantage is that oxygen is consumed at the cathode. for the measurements of oxygen in tissue, this drawback has been partially overcome by the development of minia- turized microsensors, which consume significantly less oxygen. these sensors, for which commercially available models are available with a tip diameter of to mm, are also significantly less invasive compared to larger models. despite the oxygen consumption and destruc- tiveness of the clark-type electrodes, they have been widely used and have been employed to measure the oxygen concentration in numerous plants such as rice, seagrass, green alga cultures, and in the roots of several wetland plant species (melis et al., ; visser et al., ; binzer et al., ; colmer and pedersen, ). optical oxygen sensors are popular due to their wide possible applications and their lack of oxygen con- sumption during the measurements. the majority of oxygen optodes are based on the quenching of a luminescent probe by oxygen, called phosphorescence quenching, resulting in increased phosphorescence when the oxygen concentration decreases. oxygen-sensitive phosphorescent dyes can be coated on the inside of cul- ture flasks or microplates to measure the oxygen con- centration in a sample over time. another application includes the creation of thin films coated with an oxygen- sensitive fluorescent dye, which was successfully used to map the oxygen concentration in plant roots (rudolph- moor et al., ). micro-optodes, which consist of an optical fiber with a tip coated by an oxygen-sensitive probe can be used to measure the oxygen concentration within plant tissue (licausi et al., b). however, in- sertion of micro-optodes into the tissue is destructive and facilitates oxygen diffusion into the sample, which can lead to faulty measurements. genetically encoded oxygen reporters provide a potential solution to overcome the drawback associated with the in- vasiveness of clark-type electrodes and micro-optode oxy- gen sensors (ast et al., ). several genes have been identified that display specific and strong up-regulation upon low oxygen (mustroph et al., ). the expression of these genes may therefore be used as an indication of un- derlying hypoxic conditions. activation of promoters of hypoxia-inducible genes, including hypoxia response attenuator , plant cys oxidase (pco ), and pco has been clearly demonstrated (chung and ferl, ; giuntoli et al., ; weits et al., ; gasch et al., ). oxygen measurements in nonplant organisms oxygen-sensitive phosphorescence probes are used to measure the intracellular oxygen concentration in different animal tissues (vikram et al., ). the probes are either directly injected into the desired tissue or taken up by the tissue through passive self-loading (dmitriev and papkovsky, ). afterward, the phosphorescence signal is imaged using a fluorescent microscope to map the oxygen concentration. several parameters need to be examined before phos- phorescent probes can be applied in plants, e.g. sensitivity to ph, stability, toxicity, and probe distribution. systemic distribution is another roadblock, as several dyes are in- jected intravenously in animals and rely on transport via the cardiovascular system to the tissue. a red-light- emitting iridium-based probe ir(btp) (acac) (btp) was developed and used to image tumor hypoxia in vivo (zhang et al., ). the phosphorescence of the probe is quenched by oxygen, but when the concentration drops below % v/v o the signal increases. however, cellular uptake of btp appears to be albumin-mediated, and its uptake into plant cells may therefore not occur efficiently. modification of these oxygen probes, such as the addition of hydrophilic groups or domains that interact with transport proteins, may facilitate uptake by the cell. im- portantly, as chlorophyll displays red autofluorescence, phosphorescent oxygen probes for plants should be chosen with distinct emission spectra. plant physiol. vol. , integrative oxygen sensing and signaling in plants https://plantphysiol.orgdownloaded on april , . - published by copyright (c) american society of plant biologists. all rights reserved. https://plantphysiol.org for studying the oxygen concentration in bacteria, a genetically encoded fluorescent protein-based biosen- sor for oxygen was established (potzkei et al., ). this fret-based probe contains an oxygen-sensitive yellow fluorescent protein (yfp) coupled with a hypoxia-insensitive flavin-binding fluorescent protein (fbfp). maturation of the yfp chromophore requires oxygen and therefore fret efficiency from the fbfp donor to the yfp acceptor depends on the oxygen availability. remarkably, the yfp/fbfp emission ratio could be calibrated to the dissolved oxygen concentra- tion in a range from % to %, allowing a precise quantification of the intracellular oxygen concentration. pet has been widely applied to image hypoxia within tumors in mammals. pet-based detection of oxygen is based on the imaging of f-containing im- idazoles, which passively diffuse in to cells and bind strongly to macromolecules of hypoxic cells (fleming et al., ). this can be combined with x-ray computed tomography to provide additional anatomical infor- mation of the tissue, allowing precise mapping of the oxygen concentration within the tissue (krause et al., ). another minimally invasive method to deter- mine oxygen content in mammalian tissues is f (nmr). this spectroscopic technique is based on the measurement of the spin lattice relaxation rate of per- fluorocarbons, which has a linear relation to the tissue oxygen concentration. another minimally invasive method to determine oxygen content in mammalian tissues is fluorine- nuclear magnetic resonance ( f figure . integration of multiple low-oxygen stress-signaling pathways from diverse cellular origins. according to this model, signaling to the nucleus occurs through various pathways. from left to right, low-oxygen stress results in an nadph-oxidase- derived oxidative burst, which eventually leads to posttranslational activation of diverse transcription factors (tfs). the influx of extracellular calcium stimulates a signaling cascade involving calcineurin-b-like proteins (cbls) and cbl-interacting protein kinases (cipks) and the activation of nadph oxidases, called respiratory burst oxidase homologs (rbohs). rbohs are in addition stimulated to produce ros by interacting with rho-like small g-proteins of plants (rop). the resulting ros burst is subsequently dampened through the action of rop gtpase activating protein (rop- gap ), which targets rop, as well as by hypoxia-responsive universal stress protein (hru ), which forms a complex with rop and rboh. furthermore, oxygen limitation might hamper oxidative protein folding in the endoplasmic reticulum (er) through impairing the activity of er thiol oxidase (ero), which subsequently results in an unfolded protein response (upr). in addition, low-oxygen stress causes mitochondrial dysfunction, which is communicated to the er via mito- chondrial retrograde regulation (mrr). dormant nac tfs at the er are proteolytically released to transduce the mrr signal to the nucleus. further, impairment of the mitochondrial electron transport chain (metc) is followed by a mitochondrial oxidative burst and potentially an efflux of stored calcium into the cytosol. the oxidative burst results in the activation of mitogen-activated protein kinase (mpk ) and mpk , which may regulate hypoxic gene expression by phosphorylation of transcriptional regulators. disturbance of the metc further leads to a drop in atp levels, which is sensed by the kinases targetof rapamycin (tor) and suc nonfermenting -related kinase (snrk ), whereby tor is inactivated, while snrk is induced under atp limitation. stabilization of related toapetala . (rap . ) and other subgroup vii erf tfs occurs through inactivation of the n-end rule pathway under hypoxic conditions. under aerobic conditions, this active degradation pathway involves oxygen-dependent oxidation of the tf proteins that is catalyzed by plant cys oxidase (pco). additionally, rap . protein abundance is increased by hydraulic conductivity root (hcr ), a raf-like mapkkk which targets the tf under oxygen-limiting and k+-sufficient conditions. finally, integration of the diverse subcellular signal inputs most likely occurs at the level of tfs, which are potentially regulated by posttranslational modification and induce transcriptional reprogramming resulting in hypoxia adaptation. plant physiol. vol. , schmidt et al. https://plantphysiol.orgdownloaded on april , . - published by copyright (c) american society of plant biologists. all rights reserved. https://plantphysiol.org nmr). f nmr allows imaging of the absolute oxygen concentration in tissue (yu et al., ). imaging of the oxygen concentration using pet or nmr is not limited by the thickness of the issue, and it therefore represents an effective technique to map the oxygen concentration in a noninvasive manner of thick or difficult-to-access tissue. pet and nmr-based oxygen measurements may also prove useful for plants; however, their use in mammals relies on the injection of probes in to the blood stream, and their distribution in plant tissue must therefore be carefully tested. conclusion oxygen deprivation affects diverse organelles, which give rise to unique stress signals that must be processed and integrated to initiate an appropriate adaptive re- sponse of the plant cell. the diverse and widespread consequences of a drop in oxygen for cellular homeo- stasis strongly support a view in which oxygen sensing does not occur through one primary sensor but hap- pens decentralized and simultaneously at multiple sites in the cell (figure ). at the transcriptional level, at least transcription factors are differentially expressed upon low-oxygen stress in arabidopsis (licausi et al., c). still, the roles for most of these transcription factors or the kind of signals they perceive upon low-oxygen stress are unknown. so far, it is unclear which signals activate erfviis upon low-oxygen stress in arabidopsis. the non-n-end rule erfvii target sub a of rice was shown to be a mpk phosphorylation target, (singh and sinha, ), suggesting posttranslational signal inte- gration. interestingly, mpk / activity in arabidopsis is induced by a mitochondrial signal upon oxygen deprivation (chang et al., ). also, transcription factor targets of the snrk kinase might play a crucial role in oxygen signaling (baena-gonzález et al., ). furthermore, mitochondrial- or er-to-nucleus signal- ing was shown to rely on transcription factors that need to be proteolytically activated (iwata et al., ; de clercq et al., ). one of the main challenges in the future is to identify all transcription factors that act as signal integration points during low-oxygen stress, to decipher the signals they perceive and the mechanisms through which they act in a spatial and temporal manner. to date, a number of retrograde signaling molecules have been described, including ros, calcium, and di- verse metabolites (kmiecik et al., ). still, it is hardly known how these signals act during low-oxygen stress. that said, the oxidative burst observed in mitochondria during oxygen deprivation was shown to activate mpks (chang et al., ). potentially, calcium and ros might act in synergy to form an integrative signal, as observed during salt stress (evans et al., ). organellar signaling does not only involve signaling to the nucleus but also between organelles (kleine and leister, ). here, the question raises whether low oxygen-induced signaling of one organelle can be pri- oritized over another. abiotic stresses in general impair energy metabolism and provoke mitochondrial dysfunctioning, which cause the activation of snrk and aox. in addition, signaling molecules like calcium and ros are vital to sense all dif- ferent kinds of stresses. despite this remarkable overlap in stress responses at the cellular and molecular level, cells can differentiate between stresses and respond specifi- cally. to be able to do so, plants might be capable of reading stress signal signatures (i.e. ros waves or cal- cium spikes) and sense the temporal and spatial context. in yeast and human cell systems, it was shown that cel- lular stress sensors act in scaffolds (kang et al., ). in plants, the idea of signaling scaffolds has only recently started to emerge (demir et al., ,). future research (see “outstanding questions”) should place emphasis on the multiple signaling pathways that are activated by oxygen limitation, their downstream integration, and cross-talk to reveal how the adaptation to low-oxygen stress is fine- tuned and adjusted to a particular situation encountered by plants. this will also require the 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botany, university of gujrat, pakistan b department of biochemistry and molecular biology, institute of life sciences, university of gujrat, pakistan a r t i c l e i n f o article history: received october accepted december available online january keywords: biodiesel ricinus communis l. oil product optimization feedstock * corresponding author. tel.: þ e-mail addresses: zahid.anwar @gmail.c peer review under responsibility of the e http://dx.doi.org/ . /j.jrras. . . - /copyright © , the egyptian soc open access article under the cc by-nc-nd li a b s t r a c t at present, biodiesel is gaining tremendous attention due to its eco-friendly nature and is possible substitute for diesel fuel. biodiesel as renewable energy source can be produced from edible and non-edible feedstock. non-edible resources are preferred to circumvent for food competition. in the present study fame was produced from ricinus communis l. oil by transesterification with methanol and ethanol in the presence of potassium hydroxide. the practical optimal condition for the production of biodiesel from castor bean was found to be: methanol/oil molar ratio, : ; temperature, �c; time, min; catalyst concentra- tion . g. quality assessment of biodiesel showed comparable results with astm stan- dards. the values of specific gravity (sg) were . , kinematic viscosity . cst, acid values . mg koh/g, carbon residue . %, flash point �c, fire point �c, cloud point � �c and pour point � �c of ricinus fame, respectively. based on our data, it is sug- gested that to overcome prevailing energy crisis this non-edible plant is useful for pro- duction of biodiesel, which is an alternate to fossil fuel and may be used alone or in blend with hsd in engine combustion. copyright © , the egyptian society of radiation sciences and applications. production and hosting by elsevier b.v. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). . introduction biodiesel is a renewable alternate source of petroleum and can be used in engine. it is eco-friendly, nontoxic and it is thought to be future diesel. petroleum is natural source that is rapidly depleted. biofuel is obtained from vegetable oil, algae, edible and non-edible beans like, helianthus, jatropha, pongamia and ricinus. it is derived from triglycerides and fatty acids by transestrification and esterification, respectively (bari, yu, & lim, ). . om, zahid.anwar@uog.ed gyptian society of radiat iety of radiation sciences cense (http://creativecom fossil based petroleum is not renewable stored in earth with limited reserves. world heavily depends on petroleum for transport vehicles, industrial and agricultural machinery. increase in population, industries and urbanization causes of increase in fuel combustion. it leads to removal of petroleum fuel from earth reservoirs. this higher expenditure will lead to industrial catastrophe. in cities, air contamination increases because diesel engine is a big pollution source by traffic in urban areas. carbon monoxide and carbon dioxide are rapidly increases and many other gasses from smoke are releases. u.pk (z. anwar). ion sciences and applications. and applications. production and hosting by elsevier b.v. this is an mons.org/licenses/by-nc-nd/ . /). http://creativecommons.org/licenses/by-nc-nd/ . / mailto:zahid.anwar @gmail.com mailto:zahid.anwar@uog.edu.pk http://crossmark.crossref.org/dialog/?doi= . /j.jrras. . . &domain=pdf www.sciencedirect.com/science/journal/ http://www.elsevier.com/locate/jrras http://dx.doi.org/ . /j.jrras. . . http://dx.doi.org/ . /j.jrras. . . http://dx.doi.org/ . /j.jrras. . . http://creativecommons.org/licenses/by-nc-nd/ . / j o u r n a l o f r a d i a t i o n r e s e a r c h a n d a p p l i e d s c i e n c e s ( ) e oxides of carbon and nitrogen causes headache, low blood pressure, acute bronchitis, pulmonary diseases and throat problems. because of air contamination many respiratory diseases are causes in animals and also harmful for plants. now societies are aware about air pollution caused by diesel engine, so pressure on researchers to search alternate way of diesel to reduce environmental pollution (atadashi, aroua, &aziz, ). at the present time, the world demand of en- ergy rapidly increasing because of increasing population, industrialization, and over urbanization (vasudevan & briggs, ). as increase in consumption of oil emission of pollutants increases, it will affect human health badly such as respira- tory, skin, and nervous system. increasing population and over urbanization causes energy crisis, because of energy crisis biodiesel from non-edible oil-seeds are highly in concern as alternate source of petroleum. it is non-toxic, biodegradable, renewable source, eco-friendly and cause reduction in use of petroleum. carbon that is released from burning will use by plants, enhances the life of engine, no change in engine by its use enhances rural economics. bio- diesel prepared directly from fat of animal and oil from seeds of plants by transestrification method using alcohol and catalyst (hazell & pachauri, ). . material and methods for the present research, ricinus communis l. seeds were pur- chased from makah traders pasroor, sialkot, punjab, pakistan. determination of oil or fat content from seeds has great importance on industrial scale as it effects price of raw ma- terial. soxhlet apparatus gives oil content extracted from solid source. damirchi, habibi-nodeh, hesari, nemati, & acha- chlouei, protocol of soxhlet apparatus was followed. in order to get massive quantities of oil, electrical oil expeller was used. then, oil was filtered with help of filter paper. after filtration titration was done to measure free fatty acid con- tents in it. . . pre-tests for ricinus oil in pre-tests oil quality was measured such as acid value, gravity, density, saponification and viscosity, refractive index and peroxide value. these tests were used to find out oil quality (patil and deng, ). physical characterization of r. communis was carried out according to the methods given in association of analytical chemistry (aoacs). . . transesterification transesterification is a process in which conversion of fatty acid methyl ester from crude oil occurs (ahmad, khan, zafar, sultana, & gulzar, ). oil from plants is esters of trigly- ceroides. during alcoholysis, triglyceroides is converted into di and then in monoglyceroids. on each step it needed mol of fatty acid but in experiment greater amount of alcohol added because it is a reversible reaction (dennis, wu, & leung, ). alkali alcoholysis is existing method that is frequently using for production of biodiesel, sinha, agarwal, and garg ( ); meher, vidya sagar, and naik ( ); ahmad et al. ( ). ma and hanna ( ) stated that in transesterification butanol, propanol, methanol, amyl alcohol and ethanol any alcohol can be used and used alkali catalyst. methanol is mostly used because it is cheap and it has chemical and physical advan- tages. it can easily react with alkali catalyst. in transesterification, after filtration crude filtered oil was heated in order to breakdown of triglycerides into di and mono-glycerids and to remove free fatty acids from filtered oil. it was heated on hot plate (vwr, velp- scientifica ger- many) at �c for h till oil temperature became �c, and then left it on room temperature to cool until �c. then mixture of methanol and koh and naoh were added to heated oil separately to find out the maximum fame production. then it was stirred at e rpm for min at �c. stirring time and temperature has direct effect on ester yields. it was left to settle down on room temperature for h to overnight. three layers were formed upper layer was thin soap layer, second layer was methyl/ethyl ester, third layer was glycerol. glycerol and soap were by product of trans- esterification. distilled hot water was used to purify crude methyl/ethyl ester. water amount was lowered to maximum of . % according to astm standard of biodiesel (v/v). this step was repeated e times. in order to neutralize soap and residual catalyst, washing was done at ph . , du, xu, liu, zeng, and molcatal ( ). then na so was added to pre- pared biodiesel in order to remove water. . . optimization optimization is a process in which different trail applied with variables of temperature, methanol to oil ratio, time and catalyst to examined variable effects on yield (%) were noted. optimization was done to attain the maximum ester yield. . . fuel properties fuel properties of ricinus fame are presented in table . and results were matched with astm. . results and discussion biodiesel is non-toxic, free of sulfur, renewable and alterna- tive green fuel. commonly it is produced by transesterification reaction of non-edible oil, vegetable oil and waste oil using small amount of alcohol as methanol or ethanol. its demand is rather high to produce as alternative energy sources, because availability of fossil based petroleum is rapidly decreasing. biodiesel is a potential substitute of energy because it is ob- tained from renewable energy sources. in the current study, biodiesel was extracted from castor. oil percentage was in r. communis %. . . characterization of oil oil percentage was from r. communis . for physicochemical characterization oil qualities were measured such as acid http://dx.doi.org/ . /j.jrras. . . http://dx.doi.org/ . /j.jrras. . . table e optimization effects on product yield (biodiesel, glycerol and soap) of ricinus communis. sr.# oil conc. optimization results products yield methanol to oil ratio catalyst concentration reaction time (min) reaction temp. (�c) biodiesel (gm) glycerol (gm) soap (gm) koh (gm) ch oh (gm) : . . . . : . . . . : . . . : . . . . : . . . . : . . . . : . . . . : . . . . : . . . . : . . . . : . . . . : . . . . j o u r n a l o f r a d i a t i o n r e s e a r c h a n d a p p l i e d s c i e n c e s ( ) e value, gravity, saponification, viscosity, refractive index and peroxide value (patil & deng, ). . . acid value the data revealed that . mg koh/g were acid values of crude oil ricinus. fame of castor was having . mg koh/g acid value (table ). these were compared with biodiesel standard astm d and were found in range of standards. according to this standard . was maximum acid value of biodiesel. therefore, our results were closed to patil and deng ( ) results, who reported a.v. value . and . for jatropha. . . peroxide value it is a test used to determine oil oxidative rancidity or fats measured occurrence of lipid peroxides. determined value of oil was . (table ). . . specific gravity specific gravity was . of castor and methyl ester of castor was . . our results were in range of astm d - (table ). patil and deng ( ) reported that values of canola, jatro- pha and karanja methyl ester specific gravity were . , . and . e . in order. table e fuel properties of crude oil and fame of ricinus com fuel properties crude oil astm sample castor refractive index . a saponification (mg koh/g) . e peroxide value . e cloud point e a pour point e a flash point e a fire point e a specific gravity . a ash point e a kinematic viscosity cst a acid value mg koh/g . a . . refractive index (r.i.) refractive index values were . of castor crude oil (table ). our result was much close to . of rapeseed and castor oil order as reported by saqib et al. ( ) and hlaing et al. ( ). . . saponification value saponification value was . mg koh/g of castor and crude oil (table ). wang et al. ( ) reported that saponification value . mg koh/g of jatropha crucas that was in line with our results. . . optimization through transesterification variable applied during transesterification i.e. reversible and successive numbers of reactions (du et al., ). following were our results of transesterification. . . . effect of temperature on biodiesel production ricinus at , and �c were testified and fame yield was % at �c (table ) of castor (fig. ). agarwal et al. ( ), and dorado et al. ( ) reported that using alkaline catalyst in transesterification temperature effected its yield. with increased temperature (�c) from optimum point biodiesel yield decreased. xuan et al. ( ) reported that at �c munis. biodiesel standard hsd biodiesel castor stm d - . e e e e e stm d - . �c � �c stm d - � �c � �c stm d e �c stm d �c stm d - . e . . stm d . % stm d . e . . stm d . max . http://dx.doi.org/ . /j.jrras. . . http://dx.doi.org/ . /j.jrras. . . p ro du ct y ie ld (g m ) temperature oc biodiesel glycerol soap fig. e effect of temperature on product yield (biodiesel, glycerol and soap) of ricinus communis. pr od uc t y ie ld (g m ) reac on me (min) biodiesel glycerol soap fig. e effect of time on product yield (biodiesel, glycerol and soap) of ricinus communis. j o u r n a l o f r a d i a t i o n r e s e a r c h a n d a p p l i e d s c i e n c e s ( ) e temperatures biodiesel yield was maximum from camelina oil. . . . effects of catalyst on biodiesel production variable catalyst trial gave different results on different amount. variable amount were . , . and . g (table ). biodiesel yields % were obtained with . g amount of catalyst of castor as shown in (fig. ). meher et al. ( ) re- ported that alkali catalyst amount effected on biodiesel yield in karanja and jatropha oil. . . . effect of reaction time on biodiesel production experiments were done within different time points ( , and min) to estimate the effect of time on trans- esterification reaction. with increasing time, product yield also increased within min % (fig. ). relatively higher yield of biodiesel was obtained from castor (table ). fukuda et al. ( ); freedman et al. ( ) and metsovitia et al. ( ) reported that for best results of transesterification the stirred time should be constant. however, non-edible oil stirred time was variable from min to min, but further increased in time duration decreased the product yield because of revers- ible reaction. our results were similar to findings of xuan et al. ( ) in which within min, highest biodiesel was obtained from camelina oil. . . . pr od uc t y ie ld (g m ) koh (gm) biodiesel glycerol soap fig. e effect of koh catalyst on product yield (biodiesel, glycerol and soap) of ricinus communis. . . . effects of methanol to oil ratio on biodiesel production transesterification of ricinus oil was carried out on different oil alcohol ratio ( : , : , and : ) (table ). from castor with : (methanol to oil ratio), % yield (fig. ). our results are similar to the findings of sanford et al. ( ) and ahmed et al. ( ), using methanol to oil ratio ( : ) from karanja, castor oil and from other vegetable oils, biodiesel yield was %. . . fuel properties investigation for different fuel properties were carried out e.g. carbon residue, fire point, flash point and cloud point (table ). results showed that flash point was �c of ricinus (sinha et al., ; karmee and chadha, ; demirbas, ) re- sults were similar as flash point �c of biodiesel of vege- table oil. saxena, jawale & joshipura ( ) reported that flash point range of biodiesel from vegetable oil was e �c. fire point is the temperature near but greater than flash point, where oil catches fire. biodiesel fire point was �c of ricinus (table ). raja et al. ( ) reported that fire point was �c of jatropha and �c of biodiesel of jatropha. cloud point of ricinus was � �c and pour point was near cloud point � �c and (table ). sinha et al. ( ); ahmad et al. ( ) reported that cloud point of biodiesel from vegetable oil var- ies from to � �c. kinematic viscosity of r. communis was . cst (table ). our result was much closer to . and . cst of diesel and biodiesel kinematic viscosity from : : : pr od uc t y ie ld (g m ) methanol to oil ratio biodiesel glycerol soap fig. e effect of methanol to oil ratio on product yield (biodiesel, glycerol and soap) of ricinus communis. http://dx.doi.org/ . /j.jrras. . . http://dx.doi.org/ . /j.jrras. . . j o u r n a l o f r a d i a t i o n r e s e a r c h a n d a p p l i e d s c i e n c e s ( ) e vegetable oil, as reported by guido et al. ( ) and yilmaz et al. ( ). saqib et al. ( ) found rapeseed biodiesel k.v. . (mm /sec) that is in line with our results. saxena et al. ( ) reported that kinematic viscosity of biodiesel from vegetable oil was . e . cst. . conclusion based on data it is concluded that high yield obtained from r. communis under optimum conditions. using alkaline catalyst, koh gave best results as compared to naoh catalyst. in alcohol catalyst from ch oh obtained high yield of biodiesel as compared to ch oh under optimum conditions. charac- teristics of biodiesel obtained from r. communis were compa- rable with commercially used diesel in engine for combustion. the biodiesel could be used alone or blend with commercial diesel. this may ensure to be eco-friendly and safe for envi- ronment. results revealed that after conversion of oil into fame it can be used as alternate of fossil based fuel to over- come energy crisis. r e f e r e n c e s ahmad, m., ahmed, s., hassan, f., arshad, m., khan, m. a., zafar, m., et al. ( ). base catalyzed transesterification of sunflower oil biodiesel. african journal of biotechnology, ( ), e . ahmad, m., khan, m. a., zafar, m., sultana, s., & gulzar, s. ( ). indigenous plants based biodiesel resources in pakistan. ethnobotanical leaflets, , e . atadashi, i. m., aroua, m. k., & aziz, a. ( ). biodiesel separation and purification: a review. renewable energy, ( ), e . issn: - b. bari, s., yu, c. v., & lim, h. t. ( ). performance deterioration and durability issues while running a diesel engine with crude palm oil. proceedings of the institution of mechanical engineers part d: journal of automobile engineering, , e . damirchi, s. a., habibi-nodeh, f., hesari, j., nemati, m., & achachlouei, b. f. ( ). effect of pretreatment with microwaves on oxidative stability and nutraceuticals content of oil from rapeseed. food chemistry, , e . demirbas, a. ( ). biodiesel from algae, biofixation of carbon dioxide by microalgae. applied energy, , e . dennis, y. c. l., wu, x., & leung, m. k. h. ( ). a review on biodiesel production using catalyzed transesterification. applied energy, , e . du, w., xu, y. y., liu, d., & zeng, h. ( ). comparative study on lipase-catalyzed transformation of soybean oil for biodiesel production with different acyl acceptors. journal of molecular catalysis b: enzymatic, , e . hazell, p., & pachauri, r. k. ( ). bioenergy and agriculture: promises and challenges. international food policy research institute, focus no. . karmee, k. s., & chadha, a. ( ). preparation of biodiesel from crude oil of pongamia pinnata. bioresource technology, , e . ma, f., & hanna, m. a. ( ). biodiesel production, a review. bioresource technology, , e . meher, l. c., sagar, d. v., & naik, s. n. ( ). technical aspects of biodiesel production by transesterificationda review. renewable & sustainable energy reviews, , e . patil, p. d., & deng, s. ( ). optimization of biodiesel production from edible and non-edible vegetable oils. fuel, , e . saxena, p., jawale, s., & joshipura, m. h. ( ). a review on prediction of properties of biodiesel and blends of biodiesel. procedia engineering, , e . sinha, s., agarwal, a. k., & garg, s. ( ). biodiesel development from rice bran oil: transesterification process optimization and fuel characterization. energy conversion and management, ( ), e . vasudevan, p. t., & briggs, m. ( ). biodiesel production-current state of the art and challenges. journal of industrial microbiology and biotechnology, , e . http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref 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http://refhub.elsevier.com/s - ( ) - /sref http://dx.doi.org/ . /j.jrras. . . http://dx.doi.org/ . /j.jrras. . . 	production, optimization and quality assessment of biodiesel from ricinus communis l. oil 	 . introduction 	 . material and methods 	 . . pre-tests for ricinus oil 	 . . transesterification 	 . . optimization 	 . . fuel properties 	 . results and discussion 	 . . characterization of oil 	 . . acid value 	 . . peroxide value 	 . . specific gravity 	 . . refractive index (r.i.) 	 . . saponification value 	 . . optimization through transesterification 	 . . . effect of temperature on biodiesel production 	 . . . effects of catalyst on biodiesel production 	 . . . effect of reaction time on biodiesel production 	 . . . effects of methanol to oil ratio on biodiesel production 	 . . fuel properties 	 . conclusion 	references c page.indd past president on board mary o’sullivan membership persons interested in joining the business history conference should contact the secretary-treasurer: roger horowitz, hagley museum and library, p.o. box , wilmington, de - ; e-mail: rh@udel.edu; carol ressler lockman, email: clockman@hagley.org or on the bhc website at http://www.thebhc.org/jointhebhc. complete information about the business history conference may be found on the organization’s web pages at https://thebhc.org. business and economic history, the proceedings volume of the business history conference, was published through (volume ). for the annual meeting and thereafter, the presidential address and dissertation summaries will appear in the fourth issue of enterprise & society. visit the web sites: www.journals.cambridge.org/eso and www.thebhc.org/publications/eanshome.html. license it is a condition of publication in the journal that authors grant an exclusive license to the business history conference. this ensures that requests from third parties to reproduce articles are handled efficiently and consistently and will also allow the article to be as widely disseminated as possible. authors may use their own material in other publications provided that the journal is acknowledged as the original place of publication and cambridge university press as the publisher. for full guidelines, please see our web site: https://www.cambridge.org/core/journals/enterprise-and-society/information/instructions-contributors. founded in , the business history conference (bhc) is a non-profit organization devoted to encouraging all aspects of the research, writing, and teaching of business history and of the environment in which business operates. its membership is international and representative of economists, historians, and those in allied fields, such as history of technology, accounting, labor, transportation, and government, who focus on business history as a means of understanding their subjects. bhc officers, – edward balleisen, president neil rollings, president-elect teresa de silva lopes, past-president andrew popp, secretary-treasurer ( – ) bhc trustees christy ford chapin ( – ) peter a. coclanis ( – ) paloma fernandez-perez ( – ) anne fleming ( – ) ai hisano ( – ) eric s. hintz ( – ) susie j. pak ( – ) laura phillips sawyer ( – ) heidi tworek ( – ) benjamin waterhouser ( – ) alexis yates ( – ) madeline zelin ( – ) https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core • • • cambridge core for further information about this journal please go to the journal web site at: cambridge.org/eso i n t r o d u c t i o n introduction andrew popp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . a r t i c l e s energizing finance: the energy crisis, oil futures, and neoliberal narratives caleb wellum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . reorganization of multinational companies in the western european chemical industry: transformations in industrial management and labor, s to s christian marx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . trends in the fashion business: spain and italy in comparison, – veronica binda and elisabetta merlo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . who tells your story: contested history at the nam jennifer delton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . western debates about chinese entrepreneurship in the treaty port period, – miriam kaminishi and andrew david smith . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . black power in the boardroom: corporate america, the sullivan principles, and the anti-apartheid struggle jessica ann levy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . the insurance of mass murder: the development of slave life insurance policies of dutch private slave ships, – karin lurvink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . an incomplete revolution: corporate governance challenges of the london assurance company and the limitations of the joint-stock form, – michael aldous and stefano condorelli . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . r e v i e w s https://www.cambridge.org/core/terms. https://doi.org/ . /eso. . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /eso. . https://www.cambridge.org/core 	eso_c .pdf 	eso_c .pdf << /ascii encodepages false /allowtransparency false /autopositionepsfiles false /autorotatepages /none /binding /left /calgrayprofile (dot gain %) /calrgbprofile (srgb iec - . ) /calcmykprofile (u.s. web coated \ swop\ v ) /srgbprofile (srgb iec - . ) /cannotembedfontpolicy /error /compatibilitylevel . /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves . /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel /emitdscwarnings false /endpage - /imagememory /lockdistillerparams true 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f b d e e b e e e f c c f e c c e e> /ptb <feff c a f e e f f d f d e f f d f e d d f c c e f f d e f f f d f f d f f f f e f f f e> /suo <feff b e e e e e b c b e c f c e e e e e e b e c d c f f e f f d f b d e a e c f d f b d e f e f c c a f e a c c a d d c c e> /sve <feff e e e e e e c c e e e f d c c b f d f b d e f d e c e d c f d b d f b c e b d f b d e b e f e f f f e f e e> /enu (use these settings to create adobe pdf documents best suited for high-quality prepress printing. created pdf documents can be opened with acrobat and adobe reader . and later.) >> /namespace [ (adobe) (common) ( . ) ] /othernamespaces [ << /asreaderspreads false /cropimagestoframes true /errorcontrol /warnandcontinue /flattenerignorespreadoverrides false /includeguidesgrids false /includenonprinting false /includeslug false /namespace [ (adobe) (indesign) ( . ) ] /omitplacedbitmaps false /omitplacedeps false /omitplacedpdf false /simulateoverprint /legacy >> << /addbleedmarks false /addcolorbars false /addcropmarks false /addpageinfo false /addregmarks false /convertcolors /converttocmyk /destinationprofilename () /destinationprofileselector /documentcmyk /downsample bitimages true /flattenerpreset << /presetselector /mediumresolution >> /formelements false /generatestructure false /includebookmarks false /includehyperlinks false /includeinteractive false /includelayers false /includeprofiles false /multimediahandling /useobjectsettings /namespace [ (adobe) (creativesuite) ( . ) ] /pdfxoutputintentprofileselector /documentcmyk /preserveediting true /untaggedcmykhandling /leaveuntagged /untaggedrgbhandling /usedocumentprofile /usedocumentbleed false >> ] >> setdistillerparams << /hwresolution [ ] /pagesize [ . . ] >> setpagedevice special issue on “hydrogen production technologies” processes editorial special issue on “hydrogen production technologies” suttichai assabumrungrat , ,* , suwimol wongsakulphasatch , pattaraporn lohsoontorn kim , and alírio e. rodrigues center of excellence on catalysis and catalytic reaction engineering, department of chemical engineering, faculty of engineering, chulalongkorn university, bangkok , thailand; pattaraporn.k@chula.ac.th bio-circular-green-economy technology & engineering center, bcgetec, department of chemical engineering, faculty of engineering, chulalongkorn university, bangkok , thailand department of chemical engineering, faculty of engineering, king mongkut’s university of technology north bangkok, bangkok , thailand; suwimol.w@eng.kmutnb.ac.th laboratory of separation and reaction engineering–laboratory of catalysis and materials, departamento de engenharia química, faculdade de engenharia da universidade do porto, - porto, portugal; arodrig@fe.up.pt * correspondence: suttichai.a@chula.ac.th received: september ; accepted: october ; published: october ���������� ������� according to energy crisis and environmental concerns, hydrogen has been driven to become one of the most promising alternative energy carriers for power generation and high valued chemical products. to meet the requirements of global energy demand, which continuously increase each year, efficient technologies to produce hydrogen are therefore necessary. this special issue on “hydrogen production technologies” covers outstanding researches and technologies to produce hydrogen of which their objectives are to improve process performances. both theoretical and experimental investigations were conducted for the investigation of parametric effects in terms of technical and/or economical aspects for different routes of hydrogen production technologies, including thermochemical, electrochemical, and biological. in addition, techniques used to storage and utilize hydrogen were also demonstrated. steam electrolysis reaction is a technique used to produce hydrogen through solid oxide electrolysis cells (soecs). visvanichkul et al. [ ] studied the effect of cuo addition into sc . ce . gd . zr . o (scgz) electrolyte as a sintering additive on phase formation, cell densification, and electrical performance at elevated temperature. the results showed significant effect on the sinter ability of scgz. with the addition of . wt% cuo phase transformation and impurity were not observed. however, the sintering ability of the electrolyte achieved % relative density with a large grain size at k. electrochemical performance evaluated at the operating temperature ranging from k to k under steam to hydrogen ratio at : showed activation energy of conduction (ea) of the scgz with cuo of . kj mol− compared to that without cu of . kj mol− . another work presented by gannon et al. [ ] was conducted in improving performance of electrode for water splitting under room temperature. titanium nitride coating grade stainless-steel electrode was found to be able to extend the electrode lifetime to over cycles lasting . days and was observed to outperform the uncoated material by mv. an alternative route for hydrogen production is from the conversion of solar energy. tapia et al. [ ] investigated the use of multi-tubular solar reactors for hydrogen production through thermochemical cycle using cfd modelling and simulations to design the reactor for a pilot plant in the plataforma solar de almería (psa). the developed cfd model showed its validated results with the experimental data having a temperature error ranging from % to around %, depending upon the location inside the reactor. the thermal balance solved by the cfd model revealed a . % thermal efficiency of the reactor, and ca. % of the ferrite domain could achieve the required process temperature of processes , , ; doi: . /pr www.mdpi.com/journal/processes http://www.mdpi.com/journal/processes http://www.mdpi.com https://orcid.org/ - - - https://orcid.org/ - - - http://dx.doi.org/ . /pr http://www.mdpi.com/journal/processes https://www.mdpi.com/ - / / / ?type=check_update&version= processes , , of ◦c. treatment of reactants before producing hydrogen is another technique that helps to enhance process efficiency. zaidi et al. [ ] studied the effect of using microwave (mw) and fe o nanoparticles (nps) to improve biodegradability of green algae, yielded biogas—a source of hydrogen production. their results showed both yields of biogas and hydrogen could be improved when compared to the individual ones. the biogas amount of ml and . % v/v hydrogen were produced by mw pretreatment + fe o nps. integrated techniques to improve hydrogen production performances have also been investigated. ngoenthong et al. [ ] developed a catalyst for hydrogen production from a two-step thermochemical cycle of water-splitting, applied with two different reactor types, packed-bed and micro-channel reactors. ceria-zirconia (ce . zr . o ) was found to offer better catalytic activity than fluorite-structure ceria (ceo ), which was suggested to be due to higher oxygen storage capacity. the micro-channel reactor showed times higher h productivity than the packed-bed reactor at the same operating temperature of ◦c. the better performance of the micro-channel reactor was considered as a result of high surface-to-volume ratio of the reactor, facilitating accessibility of the reactant molecules to react on the catalyst surface. chimpae et al. [ ] evaluated performance of a combined gasification and a sorption-enhanced water–gas shift reaction (sewgs) for synthesis gas production using mangrove-derived biochar as a feedstock. multifunctional material was applied in this integrated process and the effects of biochar gasification temperature, pattern of combined gasification and sewgs, amount of co-fed steam and co as gasifying agent, and sewgs temperature were studied. the studies revealed that the hybrid process could produce greater amount of h with a lower amount of co emissions when compared with separated sorbent/catalyst material. syngas production was found to depend upon the composition of gasifying agent and sewgs temperature. an integrated steam methane reforming-hydrotreating (smr-ht) pyrolytic oil upgrading process enhanced by membrane gas separation system was proposed by chen et al. [ ]. process design and process optimization were developed through simulation framework of commercial software aspen hysis along with the developed self-defined extensions for aspen hysys. the results revealed that the proposed process could provide . % conversion with . wt% hydrogen consumption and % higher net profit could be obtained when compared with the conventional process. khaodee et al. [ ] proposed systems of compact heat integrated reactor system (chirs) of a steam reformer, a water gas shift reactor, and a combustor for stationary hydrogen production from ethanol. their performances were simulated using comsol multiphysics software. as there are a number of different techniques that could be used to produce hydrogen, we therefore need to consider a selection of technologies for its production. one tool that could be used to assist decision making is data analysis. xu et al. [ ] developed a framework includes slack-based data envelopment analysis (dea), with fuzzy analytical hierarchy process (fahp), and fuzzy technique for order of preference by similarity to ideal solution (ftopsis), to prioritize hydrogen production in pakistan. five criteria, including capital cost, feedstock cost, o&m cost, hydrogen production, and co emission were taken into consideration. the results showed that wind electrolysis, pv electrolysis, and biomass gasification offered fully efficient and were recommended as sustainable selections for production of hydrogen in pakistan. high production of hydrogen demand leads also to high demand of efficient hydrogen storage system. kapoor et al. [ ] developed electrochemical hydrogen storage by integrating a solid multi-walled carbon nanotube (mwcnt) electrode in a modified unitized regenerative fuel cell (urfc). a method to fabricate solid electrode from mwcnt powder and egg white as an organic binder was investigated. the results showed that the developed porous mwcnt electrode had electrochemical hydrogen storage capacity of . wt%, comparable with commercially available ab -based hydrogen storage canisters. all the above papers show high-quality research articles on various innovative hydrogen production related technologies. the works and topics address current status and future challenges in unit scale and overall process performances. under the high demand of renewable and sustainable energy at present, we believe that these articles would find beneficial to a wide interest of readers. processes , , of we thank managing editor, ms. jamie li, all processes staff, and all contributors, for enthusiastic and kindly support of this special issue. suttichai assabumrungrat suwimol wongsakulphasatch pattaraporn lohsoontorn kim alírio e. rodrigues guest editors funding: this research received no external funding. conflicts of interest: the authors declare no conflict of interest. references . visvanichkul, r.; peng-ont, s.; ngampuengpis, w.; sirimungkalakul, n.; puengjinda, p.; jiwanuruk, t.; sornchamni, t.; kim-lohsoontorn, p. effect of cuo as sintering additive in scandium cerium and gadolinium-doped zirconia-based solid oxide electrolysis cell for steam electrolysis. processes , , . [crossref] . gannon, w.; jones, d.; dunnill, c. enhanced lifetime cathode for alkaline electrolysis using standard commercial titanium nitride coatings. processes , , . [crossref] . tapia, e.; gonzález-pardo, a.; iranzo, a.; romero, m.; gonzález-aguilar, j.; vidal, a.; martín-betancourt, m.; rosa, f. multi-tubular reactor for hydrogen production: cfd thermal design and experimental testing. processes , , . [crossref] . zaidi, a.; feng, r.; malik, a.; khan, s.; shi, y.; bhutta, a.; shah, a. combining microwave pretreatment with iron oxide nanoparticles enhanced biogas and hydrogen yield from green algae. processes , , . [crossref] . ngoenthong, n.; hartley, m.; sornchamni, t.; siri-nguan, n.; laosiripojana, n.; hartley, u. comparison of packed-bed and micro-channel reactors for hydrogen production via thermochemical cycles of water splitting in the presence of ceria-based catalysts. processes , , . [crossref] . chimpae, s.; wongsakulphasatch, s.; vivanpatarakij, s.; glinrun, t.; wiwatwongwana, f.; maneeprakorn, w.; assabumrungrat, s. syngas production from combined steam gasification of biochar and a sorption- enhanced water–gas shift reaction with the utilization of co . processes , , . [crossref] . chen, b.; yang, t.; xiao, w.; nizamani, a. conceptual design of pyrolytic oil upgrading process enhanced by membrane-integrated hydrogen production system. processes , , . [crossref] . khaodee, w.; jiwanuruk, t.; ountaksinkul, k.; charojrochkul, s.; charoensuk, j.; wongsakulphasatch, s.; assabumrungrat, s. compact heat integrated reactor system of steam reformer, shift reactor and combustor for hydrogen production from ethanol. processes , , . [crossref] . xu, l.; wang, y.; shah, s.; zameer, h.; solangi, y.; walasai, g.; siyal, z. economic viability and environmental efficiency analysis of hydrogen production processes for the decarbonization of energy systems. processes , , . [crossref] . kapoor, d.; oberoi, a.; nijhawan, p. hydrogen production and subsequent adsorption/desorption process within a modified unitized regenerative fuel cell. processes , , . [crossref] publisher’s note: mdpi stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . /pr http://dx.doi.org/ . /pr http://dx.doi.org/ . /pr http://dx.doi.org/ . /pr http://dx.doi.org/ . /pr http://dx.doi.org/ . /pr http://dx.doi.org/ . /pr http://dx.doi.org/ . /pr http://dx.doi.org/ . /pr http://dx.doi.org/ . /pr http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	references pnas .. profile of daniel g. nocera i n a dim-lit laboratory in the chemistry department at the massachusetts in- stitute of technology, a postdoctoral researcher points out the parts of a handmade device that might be our best hope yet for harnessing solar energy. a chip the size of a microscopy slide, the device is an artificial leaf, the first of its kind made of relatively abundant and inexpensive materials that, if further refined, might help make the sun our main source of energy. the brainchild of national academy of sciences member and mit chemistry professor daniel nocera, the leaf’s stainless steel chip is coated with silicon, which can harvest sunlight, and catalysts that can use that light to split water into hydrogen and ox- ygen. when burned in a fuel cell, nocera’s postdoctoratal fellow joep pijpers ex- plains, hydrogen generates electricity and water. the catalysts can help produce enough hydrogen from a liter of water to power an average home in the de- veloping world. someday, nocera hopes, this technology might help person- alize energy in the western world, un- tethering its people from power grids based on energy sources that emit planet- warming gases. although he was born in boston and returned to the city later in life, nocera spent a childhood split between four states, as he moved with his father, who worked in retail sales. that peripatetic childhood came with a price. “when you move that much, you don’t easily make friends. i became afraid to become attached to people,” he says. the anxiety of separation spurred his interest in science as a place of refuge. armed with an amateur micro- scope built from an educational kit, nocera stoked his scientific curiosity, examining creatures unearthed from his back yard. “science seemed like an in- dividual’s pursuit, something i could carry with me no matter where we moved,” he recalls. nocera soaked up the funda- mentals of science at bergenfield high school in new jersey, motivated by phys- ics and chemistry teachers. in , he enrolled for a bachelor’s degree in chem- istry at rutgers university, new jersey, where as a plucky freshman, he vol- unteered to perform experiments with chemist lester morss, who studied lan- thanides and actinides—periodic table residents that include radioactive and rare earth elements. for his under- graduate thesis under the guidance of rutgers chemist joseph potenza, nocera helped illuminate a physical phenomenon called dynamic nuclear polarization, which affects subatomic interactions be- tween electrons and nuclei. analyzing those interactions can help researchers determine high-resolution structures of biologically important molecules through methods such as nmr spectroscopy. in , nocera began doctoral studies in inorganic chemistry in the laboratory of caltech chemist harry gray. there, to- gether with caltech chemist jay winkler, nocerafashionedalaser-basedtechniqueto measure the movement of an individual electronthrough proteins, a pursuit that had preoccupied gray for nearly a decade and that could help unravel natural reactions like photosynthesis. those findings, collec- tively called fixed-distance electron transfer, led to well-regarded reports in the journal of the american chemical society ( , ) and formed the basis of nocera’s then- novel interest in using light to generate energy. but it was his paper, which reported the observation of a chemically reactive intermediate named the delta star in reactions of quadruple-bonded metals, that nocera remembers best. although the report was published in the journal of the american chemical society ( ), the research also found an unlikely outlet; the delta star became a centerpiece of a bestselling work of detective fiction by the american writer joseph wambaugh ( ) in which a band of chemistry professors help solve a mysterious murder. “the writer actually featured the abstract of the paper in the novel,” nocera recalls. trafficking electrons and protons in , just before graduation, nocera accepted an offer of assistant professor- ship from michigan state university in east lansing, michigan. there, he focused on the so-called energy problem, a cause that he has championed for most of his scientific career. nocera brought his electron transfer expertise gained in gray’s laboratory to bear on the thorny problem of multiple electron transfer. at the heart of plants’ ability to use sunlight for photosynthesis is their near-mystical knack for performing chemical reactions that involve the transfer of multiple electrons. sunlight triggers the formation of excited electronic states in plant cells that, through a cascade of steps, lead to the coupling of protons and electrons, ultimately producing hydrogen and oxygen. it is a testament to the fiendish difficulty of replicating this chemical reaction—which plants carry out with casual ease—that a century after italian chemist giacomo ciamician wrote in science that “the photochemical pro- cesses that hitherto have been the guarded secret of the plants . . . will have been mastered by human in- dustry,” researchers are still trying to perfect artificial photosynthesis ( ). long considered a hurdle to harnessing sunlight, the field of multielectron chem- istry presented problems that nocera addressed through kinetic studies using lasers. among the first chemical reactions he addressed was the transfer of two electrons to an atom of hydrogen, a re- action catalyzed by hydrogenase enzymes, which help orchestrate anaerobic metab- olism in organisms like algae. under- standing how algae carry out the reaction, for example, could help researchers gen- erate hydrogen for use as a fuel. more importantly, multielectron chemistry turned out to be a gateway to a more complicated reaction called proton-cou- pled electron transfer (pcet), whose unraveling earned nocera membership in the national academy of sciences years later. pcet pointed to a way to harness sunlight. such limber explorations of subatomic chemistry led to an assistant professorship in at mit, where nocera set about unifying the phenomena of multi- electron chemistry and pcet as a path toward addressing the energy problem. through nifty calculations that accounted for worldwide population, average gross daniel g. nocera. this is a profile of a recently elected member of the na- tional academy of sciences to accompany the member’s inaugural article on page in issue of volume . www.pnas.org/cgi/doi/ . /pnas. pnas | january , | vol. | no. | – p r o f il e d o w n lo a d e d a t c a rn e g ie m e llo n u n iv e rs ity o n a p ri l , domestic product per capita (a measure of productivity), and energy consumed per unit of gross domestic product (a measure of energy conserved while achieving that productivity), nocera estimated in a pnas perspective that, by the turn of the century, the global demand for energy would hover around a staggering trillion watts ( ). although fossil fuels, like coal, oil, and natural gas, can to- gether meet that demand handily, their use is forever pinned with an asterisk: climate change caused by the emission of greenhouse gases. achieving the emis- sions reduction goals set by the in- tergovernmental panel on climate change, then, would call for a reliable source of carbon-neutral energy. high noon for solar energy nocera turned to an unfailing source: a benchmark for reliability, the sun provides more energy in an hour than people typi- cally consume in a year. and there are two main ways to harness that energy, namely producing steam by using turbines or converting sunlight into electricity by using photovoltaic panels. but the challenge in harnessing solar energy lies in the ability to storethecapturedenergyforuseatnightor when the sun is blanketed by clouds. a few ways to store solar energy at night have been developed, like entrapping the excess energy in molten salt or compressed air. but none are cost-effective enough to render solar energy an industrial option. in seeking a practicable solution to this seeming impasse,nocera lookedtonature. his unraveling of multielectron chemistry and pcet led to a quest to mimic pho- tosynthesis. to that end, he sought an in- expensive catalyst that could use sunlight to split water into hydrogen and oxygen. the gases could then be combined in a fuel cell to generate electricity and water, thus creating a potentially bottomless, self- sufficient powerhouse. “photosynthesis is a water-splitting reaction and involves four electrons and four protons. plants store and move four electrons from water and produce an electric current. they also convert the electric current into chemical current conducted by protons, which are moved as atoms. atoms are heavier and tougher to move than electrons. what we needed was a catalyst that could move atoms and assemble them,” nocera explains. by , nocera had developed a rho- dium-based catalyst to generate hydrogen gas from a chemical solution using light energy to make hydrogen atoms from protons and electrons wrested from the solvent. meanwhile, other researchers at the us national renewable energy laboratory in golden, colorado, had uncovered ways to use semiconductors to split water. but rhodium and semi- conductors are too expensive for large- scale use. also, there was still no reasonable means to generate oxygen from water. “reading the book of nature helped us move closer to an inexpensive catalyst for oxygen,” nocera says. a re- vealing chapter in the book came to light when london’s imperial college bio- chemist james barber published the high- resolution crystal structure of the enzy- matic machinery that helps plants carry out photosynthesis. known as the oxygen- evolving complex, this macromolecular structure was found to be the secret behind plants’ photosynthetic prowess. “when we saw what the plant’s catalytic machinery looked like, we set out to design a synthetic catalyst to split water,” he adds. thanks to a national science foundation grant to explore renewable energy sources and a private, philan- thropic gift, nocera set up an energy research program at mit called the solar revolution project, one of whose goals was to develop such a catalyst. bolstered by the influx of research dol- lars, nocera and his then-postdoctoral fellow matthew kanan fashioned a process that could produce hydrogen and oxygen from water. the process involves an elec- trode made of indium tin oxide, which when subjected to a voltage in a catalytic solution of cobalt, potassium phosphate, and water, generates oxygen gas and hydrogen ions. at a different electrode coated with a platinum catalyst, the hy- drogen ions recombine into hydrogen gas. as the reaction proceeds, the cobalt cat- alyst breaks down—but reassembles over time, regenerating itself for prolonged use. published in a science report, nocera’s process was hailed as a break- through ( ). over the course of a day, the catalyst could use electricity generated by a photovoltaic panel to split water and produce energy to power an average american home. the strength of the cat- alyst, nocera explains, was in its ability for near-continuous self-repair, not to men- tion the relative safety, abundance, and affordability of raw materials such as co- balt and phosphate. “the real scientific discovery was its self-healing property, which resembles that of the oxygen- evolving catalyst of photosynthesis,” no- cera says. yet nocera’s catalyst had a number of shortcomings that needed to be addressed. first, the catalyst needed a good deal of electricity to start splitting water, affecting its overall efficiency. complicating the matter further, it could only accept low levels of current. further still, the platinum used to generate hy- drogen was prohibitively expensive for nocera’s purpose. in the next two years, nocera and his team surmounted some of those problems, publishing in a pnas inaugural article, an improved ox- ygen-evolving catalyst based on nickel borate ( ). at a ph of . , thin films of the catalyst, the paper reported, could be electrodeposited from dilute solutions of nickel borate electrolyte, allowing re- searchers to control the thickness of the films and the electric potential at which the catalyst operates. “structurally, the nickel–borate catalyst is similar to the cobalt catalyst, but it runs faster and better in certain ph regimes. it also shows that our original discovery isn’t an isolated curiosity,” nocera says. “our focus is now on this nickel–borate cata- lyst,” he adds. no mere pie in the sky to help commercialize the water-splitting catalyst, nocera cofounded sun catalytix, a massachusetts-based technology firm that hopes to put his basic research advances to work for people. the com- pany’s long term goal is to personalize energy by producing it at its point of use instead of relying on traditional methods of distribution along grids from a central- ized source. in a tidily imagined scenario, nocera envisions turning surplus light energy harvested by rooftop photovoltaic panels into electricity with the help of his water splitter, a pair of underground tanks to store hydrogen and oxygen, and a fuel cell to burn the hydrogen. “thus, an artificial leaf. | www.pnas.org/cgi/doi/ . /pnas. nair d o w n lo a d e d a t c a rn e g ie m e llo n u n iv e rs ity o n a p ri l , your home becomes its own solar power station,” nocera explains with his char- acteristic can-do spirit. in september , national geographic featured a snapshot of nocera cradling little more than a gallon of water in his hands—the amount that he estimates is needed to power an average american home. a vision of pharaonic scope that nocera hopes to someday pull off, personalized energy must first overcome several hur- dles, not least of which are the still- prohibitive cost of fuel cells and the po- litical inertia facing alternative energy. “over the years, we’ve been getting greener in thinking about the future of our energy, but it’s still largely carbon- based. the slow pace of greening is disappointing, mainly because of the lack of policies to implement carbon pricing,” he says. intertwined with this vision to wean the western world from its dependence on fossil fuels is nocera’s goal to make solar energy a predominant resource in de- veloping countries, which remain rela- tively independent from large power grids. but most photovoltaic panels are made of semiconductors like silicon, whose high cost would rapidly scupper plans to commercialize personalized en- ergy in poor countries. which is why nocera developed a workaround by further improving his water-splitting catalyst. “there’s a lot of cost going into the fabrication of the photovoltaic panel. if i could show there was a way to integrate the silicon directly on the catalyst, i wouldn’t need a panel,” he says. that is precisely what he showed to a room full of scientists and engineers at a march meeting of the american chemical soci- ety in anaheim, california. the demon- stration doubled as a preview to a pnas paper describing his version of an artificial leaf ( ). based on the oxygen- evolving complex of leaves, nocera’s de- vice is composed of a slender film the size of a business card that bears crystalline silicon cells covered with a layer of in- dium tin oxide and containing his cata- lysts. as sunlight hits a beaker of water into which the leaf is immersed, oxygen and hydrogen bubble up from separate sides of the leaf. by directly placing his catalysts on the silicon, nocera obviated the need for a photovoltaic panel. “this is really what i started out to do in gray’s lab—to make an unsupported device that could split water with nothing else but sunlight,” nocera says. in laboratory set- tings, nocera showed, the artificial leaf worked continuously for three days. no- cera has struck a partnership with indian businessman ratan tata to help harness solar energy in parts of rural india, and he hopes that a prototype artificial leaf might be ready for use in people’s homes within a few years. nocera’s efforts to harness solar energy earned him a place in time magazine’s list of the most influential people, an honor that he shared with us secretary of energy steven chu. “the recognition was noteworthy, because we were among the few scientists who made the list that year,” nocera recalls. his commitment to solving the energy crisis runs beyond the often-closeted world of academia. to help demystify scientific efforts to use solar energy to solve the energy crisis, nocera has partnered with the mit museum and the boston mu- seum of science, mounting exhibits that have enthralled visitors. “people often think that cool discoveries are made by technocrats. what they don’t get is that they are enabled by basic science,” nocera says. “my goal is to help people see the road between basic science at places like mit and technology in the real world.” prashant nair, science writer . winkler jr, nocera dg, yocom km, bordignon e, gray hb ( ) electron-transfer kinetics of pentaam- mineruthenium(iii)(histidine- )-ferricytochrome c. mea- surement of the rate of intramolecular electron transfer between redox centers separated by Å in a protein. j am chem soc : – . . nocera dg, winkler jr, yocom km, bordignon e, gray hb ( ) kinetics of intermolecular and intramolecular electron transfer from ruthenium (ii) complexes to ferri- cytochrome c. j am chem soc : – . . nocera dg, gray hb ( ) electron transfer chemistry of the luminescent excited state of octachlorodirhenate (iii). j am chem soc : – . . wambaugh j ( ) the delta star (bantam publishers, new york). . ciamician g ( ) the photochemistry of the future. science : – . . lewis ns, nocera dg ( ) powering the planet: chemical challenges in solar energy utilization. proc natl acad sci usa : – . . kanan mw, nocera dg ( ) in situ formation of an oxygen-evolving catalyst in neutral water containing phosphate and co +. science : – . . dincă m, surendranath y, nocera dg ( ) nickel-bo- rate oxygen-evolving catalyst that functions under be- nign conditions. proc natl acad sci usa : – . . pijpers jj, winkler mt, surendranath y, buonassisi t, nocera dg ( ) light-induced water oxidation at silicon electrodes functionalized with a cobalt oxygen-evolving catalyst. proc natl acad sci usa : – . nair pnas | january , | vol. | no. | d o w n lo a d e d a t c a rn e g ie m e llo n u n iv e rs ity o n a p ri l , microsoft word - woo_egy_ _ _final.doc market efficiency, cross hedging and price forecasts: california’s natural-gas markets c.k. wooa,b,*, a. olsona, i. horowitzc,d,e a energy and environmental economics, inc., sacramento street, suite , san francisco, ca usa b hong kong energy studies centre, hong kong baptist university, hong kong c decision and information sciences, warrington college of business administration, university of florida, gainesville, fl - d information and decision systems, college of business administration, san diego state university, san diego, ca - e school of accounting and finance, hong kong polytechnic university, hong kong received september abstract an extensive north american pipeline grid that physically integrates individual natural- gas markets, in conjunction with economic ties binding the california markets to those at henry hub, louisiana and the new york mercantile exchange via an array of financial instruments, suggests that the spot prices at henry hub will impact those in california. we verify the suggestion via a partial-adjustment regression model, thus affirming that california traders can exploit the cross-hedging opportunities made available to them via market integration with henry hub, and that they can accurately forecast the price they will have to pay to meet future demand based solely on the price of futures at henry hub and the price of a california natural- gas basis swaps contract. * corresponding author. tel: + - - - ; fax: + - - - . email address: ck@ethree.com (c.k. woo) . introduction natural-gas market reform and deregulation has been an on-going process for almost two decades, resulting in the emergence of wholesale spot markets that span north america [ ]. previous empirical evidence supports the hypothesis of market integration and price convergence across these markets [ - ]. that evidence notwithstanding, california’s natural-gas price skyrocketed from nearly $ per million british thermal units (mmbtu) to over $ /mmbtu from november to december [ ], a ten-fold increase that far exceeded the contemporaneous rise in spot prices at henry hub in louisiana, the nation’s largest natural-gas spot market. notwithstanding the pipeline explosion in new mexico in august [ ], the california natural-gas price spike has been attributed to dysfunction in the state’s natural-gas markets that “fed off misconduct, including gas transaction misreporting and wash trading.” [ , p. ]. since the end of the california energy crisis in june , however, california’s natural- gas spot markets have once again been relatively calm. this suggests that the california market dysfunction is an isolated event, at odds with the economic ties that directly bind the california markets to those at henry hub, including the futures market operated by the new york mercantile exchange (nymex), comprise a variety of financial instruments, including swaps, basis contracts, and futures contracts. as shown in fig. , the physical ties evolving from the pipeline grid both directly and indirectly link the california markets to those throughout north america, including canada. these economic and physical ties lead us to posit that the california electricity and natural-gas crisis period was an intermediate-term two-pronged aberration from the long-term tendency of those gas markets to behave efficiently, insofar as their spot-price movements are linked to those at henry hub. and if the california natural-gas markets are efficient, this opens up the possibility of traders taking advantage of the aforementioned financial instruments in order to inure themselves from the risks that go along with reliance on potentially volatile natural-gas spot markets. we address these issues simultaneously through a single-equation partial-adjustment regression model that pays due obeisance to a california trader’s ability to cross hedge via the henry hub futures market. admittedly simple, the model parsimoniously characterizes the california natural-gas price behavior. a case in point is the energy-crisis issue. based on the federal energy regulatory commission's (ferc) report [ ] on price manipulation in the western markets and the chronology of events detailed by various researchers [ , - ], the model incorporates dummy variables to account for each of the prongs, notably, the electricity- crisis period from may to june , and the natural-gas crisis period from november to may and estimates the dollar impact of these crises on the daily spot prices in two california gas markets: pg&e citygate and socal gas (topock). with regard to the market-efficiency and cross-hedging issues, the estimated regression coefficients enable us to infer that, except for the aberrant period identified by the ferc [ ] and other researchers [ , - ], california’s natural-gas spot markets have indeed been efficient, with prices in those markets moving in synch with those at henry hub. the inference, in turn, has important implications for traders in two related regards. first, california traders can accurately forecast the price they will have to pay to meet future demand based solely on the futures price at henry hub, or in tandem with the price of a california natural-gas basis swaps one can econometrically identify the crisis periods by solving for the crisis' beginning and ending dates that minimize (maximize) the regression model's sum of squared errors (likelihood function). we did not do so because of (a) the evidence already documented in the extant literature on the california energy crisis; and (b) the unlikely gain in insights from such an econometric exercise. as will be seen in section , our choice of crisis periods yields estimates of the anomalous increases in california natural-gas prices that are close to those found by ferc [ ]. contract when such is traded. second, traders in california’s spot markets can cross hedge via the nymex futures market for henry hub delivery in order to reduce their exposure to the risk entailed in the price volatility common to commodity markets in general. . modeling considerations natural-gas traders are concerned with both the current spot price, p, at which they may have to acquire gas and the price they will pay to meet demand at some future time t, pt. they may, however, have the option of locking in the latter price through the purchase of one or more fixed-price forward contracts. nymex, for example, has been offering monthly natural-gas futures contracts since april , with the future currently extending as far as a -month time horizon. moreover, in addition to being able to purchase natural-gas futures for delivery in an external market such as henry hub at a fixed price of pf per mmbtu, nymex also offers to traders buying gas in local markets such as pg&e citygate or socal gas natural-gas swaps contracts at a price of psf. in this case, the trader has a perfect forecast of the time-t price: pft = psf + pf. ( ) to determine whether the trader will actually be willing to pay that price at time t, consider a spot-price regression that relates the spot price for a local delivery location without forward/futures trading, such as pg&e citygate, and the spot price pet in an external market with forward/futures trading, such as henry hub: pt = α + βpet + εt. ( ) here, α and β are coefficients to be estimated, and εt is a random-error term with the usual normality properties, including zero mean and finite and constant variance σ > . buyers can cross-hedge their costs per mmbtu by going to the external market, buying β mmbtu of forward gas at the fixed price of pf, taking delivery at future time t, and then selling β mmbtu in that external market at the market’s spot price of pet. the buyer thus earns a profit of β(pet – pf). the buyer that pays pt in the local spot market therefore has a net cost per mmbtu of pt - β(pet – pf) = α + βpet + ε – β(pet – pf) = α + βpf + ε. the net-cost variance is the σ > that cannot be reduced by cross hedging. if pft < α + βpf, the buyer’s expected profit per mmbtu is (α - psf) + (β - )pf. the buyer earns that profit by purchasing basis swap contracts at a cost of psf and external-market futures at a price of pf, and selling natural-gas forward to another trader at a price of α + βpf. conversely, if pft > α + βpf, a trader can cross-hedge the local-market spot price and sell both basis swap contracts and henry hub futures contracts so as to earn an expected positive profit of (psf - α) + ( - β)pf per mmbtu. since a positive expected profit cannot persist in a market with active spot and futures trading, in order for eq. ( ) to hold it must be true that α = psf and β = , in which case eq. ( ) provides a perfect natural-gas price forecast. the estimates of α and β, denoted by a and b, are obtained through a partial-adjustment model that is a variation on a theme explicated in detail in [ , ]. using the present notation, that model permits one to infer a and b from the parameter estimates of eq. ( ): pt = θ + γpet + φpt- + μt. ( ) eq.( ) is a linear specification as implied by the law of one price and the economic reality that traders’ cross- hedging strategies are based upon the prices in the separate markets rather than upon the logarithms of those prices. the linear specification thus allows for a straightforward test of the market-efficiency hypothesis of α = and β = under negligible transportation costs. that being said, we acknowledge that others (e.g. [ ]) have explored the market-integration issue through a log-linear specification, albeit not with our hedging perspective. in recognition of that alternative, we also estimated the regression models reported in section in log-linear form. at least in terms of the signs of the parameter estimates and their statistical significance, as well as corresponding tests on the residuals, there was nothing to distinguish the linear and the log-linear specifications. here, θ = α λ, γ = β λ, φ = ( - λ), and μt = λεt; where ≤ λ ≤ measures the extent to which daily prices adjust to an unobservable long-run equilibrium price for that day, with λ = implying a complete lack of adjustment and λ = implying instantaneous adjustment. when μt has the familiar white-noise properties that we would like to ascribe to a random-error term, using ordinary least squares (ols) to estimate eq. ( ) will yield unbiased and precise coefficient estimates so long as the random errors, μt, are not serially correlated. to allow for the possibility of serial correlation in which the random-error term follows a kth-order autoregressive process, ar(k), we set μt = Σjρjμt-j + ωt, where ωt is white noise (with the desired normality properties) and j = ,…, k [ , chapter ]. we then substitute μt = Σjρjμt-j + ωt into eq. ( ) and estimate it using the maximum likelihood (ml) procedure, thus avoiding any potential bias caused by the possible correlation between pt- and μt. . data fig. shows daily natural-gas prices at pg&e citygate and socal gas for the historical period that spans our sample data: namely, some six years in the former and eight years in the latter case. these data span the energy-crisis periods for the western electricity and natural-gas markets. fig. indicates relatively stable gas prices of under $ /mmbtu, except for the natural- gas-crisis period of november to may when daily prices at times exceeded $ /mmbtu. fig. shows electricity prices at south of path (sp ) and north of path (np ), the two major delivery points in california’s wholesale electricity market. this figure shows that the daily peak period ( : - : , monday-saturday) electricity prices were typically below $ /mwh, except during the electricity-crisis period of may to june when the prices at times exceeded $ /mwh. to capture in our model the effects of these two known crises, we introduce into eq. ( ) a pair of binary independent variables: (a) cel = during the electricity-crisis period of may to june , and zero otherwise; and (b) cng = during the natural-gas crisis period of november to may , and zero otherwise. the crisis indicators isolate the price effect of these two unusual events characterized by extreme weather, capacity shortage, market-power abuse, and falsely reported natural-gas prices [ - , ]. thus, we apply ml estimation to the following regression equation: pt = θ + κ cel + κ cng + γpet + φpt- + Σjρjμt-j + ωt. ( ) the estimate of κj is denoted kj and that of ρj is denoted rj. the estimates of θ, γ, φ, and λ are denoted f, g, h, and l, respectively. two sets of data provided by platts comprise our two samples of observations for the dependent variable. the first sample contains , daily pg&e citygate volume-weighted average prices for the period of may to mid-august . the second sample contains , daily socal gas (topock) volume-weighted average prices for the period of july to mid-august . corresponding observations are available for the daily henry hub volume- weighted average spot prices. although “the quality of reporting to price index developers (including platts) improved substantially” after [ , p. ], some of the earlier data, most notably during the energy crisis, reflect trade manipulation and gaming the market by large traders such as enron. insofar as any “epidemic” of false reporting impacts our estimates, one would expect that impact to detract from our ability to draw statistically-significant conclusions that support our model. as will be seen, however, this does not appear to be the case. table reports summary statistics for the prices at pg&e citygate, socal gas and henry hub, for the full sample as well as for sub-samples of the pre-crisis, crisis, and post-crisis periods. the summary statistics reveal that during the full sample period the california spot- market prices tended to be both higher and more volatile than were the henry hub prices, while being moderately correlated ( . ≤ r ≤ . ) with those at henry hub. prior to going forward with the ml estimation of eq. ( ), it is first necessary to assure that the time series for the two economic variables in the equation, pt and pet, are stationary. were they otherwise, this would violate an underlying assumption of regression analysis and lead to what granger and newbold [ ] dubbed a spurious regression whose high coefficient of determination and t statistics belie any true economic meaning. the acknowledged test for stationarity is the augmented dickey-fuller test [ ], the results of which are also reported in table . the critical value of the augmented dickey-fuller (adf) statistic for our sample sizes of n = , and n = , is – . (p = . ) [ , p. , table . ]. an adf test statistic below – . allows us to reject the hypothesis that the time series is not stationary and has a unit root. the adf statistics in table are computed with one lagged difference, a non-zero mean (drift), and no trend. we have also run this model using the phillips-perron test [ ] and the statistical inferences are precisely the same. we have also run alternative versions of both tests, with trend, and with lagged differences of up to ten days, and verified that our results and the inferences are robust, insensitive to the specification of either the dickey-fuller fundamental “testing” equation or the test employed. we therefore conclude that none of the three price series is non-stationary, either before the electricity crisis or over the entire sample period – from mid- for pg&e city gate and from mid- for socal gas, through mid-august . this empirical evidence of stationary price series’ is an exception to the common finding in extant literature [e.g., - ] that energy prices typically follow a random walk. we do not have a ready explanation for this exception, other than the fact that our data series cover a more recent sample period that extends from the mid s to august . we cannot, however, reject the unit-root hypothesis for either the pg&e citygate or socal gas time series after the electricity crisis, or for the henry hub sequence of prices during the crisis. though only present in the sub-periods, non-stationary price series raise the possibility that our regression results may be spurious [ , - ]: the estimated version of eq. ( ) indicates an apparently significant relationship between california and henry hub natural-gas prices when in fact no such relationship exists. hence, our estimation of eq. ( ) will include a cointegration test of the null hypothesis that the regression residuals follow a random walk [ , chapter ], we ran these additional tests in response to the urgings of a referee whom we thank for helping us to solidify our confidence in the results and their implications. our focus on the adf test statistics rather than the phillips-perron test statistics is prompted by green's [ , p. ] observation that "[t]he dickey-fuller procedures have stood the test of time as robust tools that appear to give good results over a wide range of applications. the phillips-perron tests are very general, but appear to have less optimal small-sample properties." assuredly, with our large-sized samples the latter qualification would not apply. causing spurious regression results due to the california and henry hub natural-gas prices drifting apart without limit over time. both before and after the crisis, the differences between the average prices and their standard deviations for the three markets are quite modest, which suggests that the higher overall means and standard deviations for the california markets relative to those at henry hub is an aberration of the crisis period. the lowest correlations, which range from . to . , of the california-market prices with those at henry hub also occur during the crisis period, hinting at a market disconnection during this period, which reduces the correlation coefficients for the entire sample. . the estimated regression coefficients . pg&e citygate table a reports the estimated coefficients for four autoregressive-error forms of the pg&e citygate price regression: ar( ), ar( ), ar ( ), and ar( ). the numbers in parentheses are the respective t-ratios. with almost identical root-mean-squared-errors, all four regressions explain at least % of the pg&e citygate price variance, suggesting that the nymex natural- gas futures is an effective hedge instrument. the likelihood (llh) ratio test results and the akaike information criterion (aic) values indicate that the errors may follow an ar process of the fourth or higher order. with the exceptions of the intercept, the electricity-crisis indicator, and one ar( ) parameter (r = . ), all of the coefficient estimates are statistically significant (p < . ). the estimates for any single regression parameter vary across the four ar specifications. irrespective of the ar specification, however, the values for h are highly significant. since the corresponding values for l are determined from l = – h, when h is significantly different from zero, l is significantly different from one and decisively rejects the instantaneous-adjustment hypothesis. to illustrate the sensitivity of the estimates to ar specification, consider the estimated coefficients for l: namely, l = – . = . under the ar( ) specification, l = . under the ar( ) specification, l = . under the ar( ) specification, and l = . under the ar( ) specification. based on ( / l) which is an estimate of ( / λ), the corresponding numbers of days required for the local market to regain a perturbed equilibrium are . , . , . , and . , respectively. the speed with which the market returns to the local equilibrium price suggests it is feasible to apply the equilibrium-price condition for the purpose of forecasting prices for an extended period of time, say over a year. the combined effect of the electricity crisis and the natural-gas crisis on the daily spot price is the sum of the estimated regression coefficients, k and k . this effect ranges from a high of k + k = . + . = $ . per mmbtu for the ar( ) specification to a low of . + . = $ . per mmbtu for the ar( ) specification. at the market equilibrium, the effect is magnified by a factor of /l. taking the four values of l into account gives estimates of . / . = $ . per mmbtu for the ar( ) specification, . / . = $ . per mmbtu for the ar( ) specification, . / . = $ . for the ar( ) specification, and . / . = $ . per mmbtu for the ar( ) specification. this large effect confirms the earlier hint that during the energy-crisis period, the pg&e citygate market disconnected from the henry hub market. in all four cases, however, k dwarfs k , so that only a minor portion of the rise in natural-gas prices during the energy crisis can be attributed solely to the electricity crisis. further support for our assertion that except for the crisis periods, the pg&e citygate and henry hub prices are cointegrated is provided by the adf statistics on the residuals from the four regressions. these statistics enable us to reject the null hypothesis that the residuals follow a random walk and have a unit root [ , chapter ]. table a suggests that the estimates are sensitive to the ar error specification. if this sensitivity extends to a and b in the market-equilibrium condition, it forces us to question the validity of using cross hedging to develop a natural-gas price forecast. hence, we test the hypothesis that neither α nor β varies by ar error specification. if the data do not reject this hypothesis, we can safely conclude that the equilibrium-price condition is robust and suitable for developing a market-based natural-gas price forecast. table b presents the results of testing two null hypotheses: α = and β = . the former tests the hypothesis that the basis differential is equal to zero. the latter tests the hypothesis that the pg&e citygate and henry hub natural-gas markets are efficient without persistent arbitrage profit; and with β equal to unity being the optimal hedge ratio, which would be the case when the traders’ objective is to use hedging to minimize the price variance [ ]. neither of the null hypotheses can be rejected at even the loosest of possible rejection standards (p = . , say), irrespective of the ar specification. assuredly, on any given day the basis swaps price might deviate from zero. our estimate of a ≈ is the average basis swaps price for the sample period, which fails to reject the hypothesis that α = . fig. , for example, displays the nymex basis swaps prices for pg&e citygate on september , for the -month period of october to october . these prices fall well within the % confidence interval for the basis differential estimate in table b, thus lending statistical and visual support to our conclusion that, except for the crisis periods, the pg&e citygate market is efficient. . . socal gas table a reports the analogous results for the socal gas spot-price regression with ar( ), ar( ), ar( ), or ar( ) error specification. all four regressions have identical root- mean-squared-errors and each regression accounts for % of the spot-price variance. the llh ratio test results and aic values indicate an ar error process that is unlikely to be of the fifth or higher order. with the exception of the intercept, the electricity-crisis indicator and two ar parameters, all coefficient estimates are statistically significant (p < . ). the coefficient estimates vary across the first three ar specifications, but not between the third and the fourth. once again, however, the estimates for φ are highly significant, decisively rejecting the hypothesis of instantaneous adjustment. specifically, the four estimates of λ are l = . under the ar( ) specification, l = . under the ar( ) specification, l = . under the ar( ) specification, and l = . under the ar( ) specification. the corresponding numbers of days required for the local market to regain equilibrium is . , . , . , and . , respectively. this range of required days is smaller than the one for pg&e citygate because as fig. shows, the major supply basins (san juan basin, permian basin, and anadarko basin) serving southern california are better inter-connected with henry hub than those (western canadian sedimentary basin and rocky mountain basin) serving northern california. this narrow range of small values further reinforces the notion that it is feasible to apply the equilibrium-price condition for the purpose of forecasting natural-gas prices for an extended period of time. table a indicates that the spot-price effect of the electricity and natural-gas crises ranges from a high of . + . = $ . per mmbtu for the ar( ) specification to a low of . + . = $ . per mmbtu for the ar( ) specification. at the market equilibrium, the effects are . / . = $ . per mmbtu for the ar( ) specification, . / . = $ . per mmbtu for the ar( ) specification, . / . = $ . for the ar( ) specification, and . / . = $ . per mmbtu for the ar( ) specification. as was true for pg&e citygate, this large effect again confirms the earlier hint that during the energy crisis, the socal gas market disconnected from the henry hub market, although the disparities between the k and k values are not as great as in the earlier case. thus, the electricity crisis played a more important role in the rise in socal gas prices during the energy crisis than was the case for pg&e citygate prices. finally, again as was the case with the pg&e sample, the adf statistics for the unit-root test reject the hypothesis that the residuals for the socal gas regressions have a unit root, which suggests that the coefficient estimates are not susceptible to spurious interpretation. since table a suggests that the coefficient estimates are sensitive to ar error specification, table b tests the sensitivity of a and b to any such error. as was true for pg&e citygate, table b shows that the equilibrium-price condition is robust, and thus suitable for developing a market-based natural-gas price forecast. and once again we cannot reject the null hypothesis α = and β = , which implies that except for the crisis periods, the socal gas and henry hub natural-gas markets are efficient without persistent arbitrage profit, and with an average basis differential of zero and an optimal hedge ratio of unity. fig. shows that the nymex basis swaps prices for socal gas on / / for october to december fall well within the % confidence interval for the basis differential estimate in table b, thus affirming our conclusion that the socal gas market is efficient. . conclusions the integration of natural-gas markets since open access and deregulation in the mid- s suggests that those of california should be efficient and bereft of the potential for persistent arbitrage profit. with the caveat that the energy-crisis period was an important exception, our analysis supports the suggestion. specifically, the average difference between the california and henry hub prices is close to zero. ceteris paribus, a $ per mmbtu change in the henry hub price translates into a $ per mmbtu change in the california price, over all ar error specifications. a key implication of our model is that traders can accurately forecast the natural-gas prices they will have to pay to meet demand. when there is trading for natural-gas futures and basis swaps contracts, this price forecast is the price of a henry hub futures contract and the price of a basis swaps contract. when the only trading is in natural-gas futures, the price forecast is simply the price of a henry hub futures contract, because the estimated basis differential is not significantly different from zero. in light of the short time required for the restoration of a perturbed equilibrium and the current availability of five-year futures contracts, a five-year forecast time horizon seems eminently viable. and an accurate five-year price forecast provides an important input to management in three especially salient decision-making contexts. first, a spot-price forecast is useful to natural-gas suppliers that are involved in pricing a natural-gas forward contract, a usage demonstrated by [ ] for the closely related case of electricity. second, the forecast and its dispersion are critical input data for cost-risk management by such purchasers of natural gas as local distribution companies (ldcs) that resell the gas to their retail end-users and gas-fired generation owners, an application demonstrated by [ , , ] for an electricity ldc. third, evaluating the cost-effectiveness of natural-gas demand management (e.g., boiler efficiency improvement) requires a comparison of the gas- price forecast and the cost of reducing gas demand. finally, during the energy crisis the pg&e citygate spot price is estimated to have been more than $ /mmbtu in excess of the non-crisis price expectation, and the socal gas spot price is estimated to have been almost $ /mmbtu in excess of the non-crisis price expectation. these estimates corroborate the corresponding $ . /mmbtu and $ . /mmbtu figures found by ferc [ ]. under the conservative assumption of a marginal generation unit’s heat rate of , btus per kilowatt hour, the excess above normally expected natural-gas price levels could have contributed $ to $ per megawatt hour to the electricity price spike during the california electricity crisis. this is notwithstanding that it has been shown that other factors, such as capacity shortages and market-power abuses by large electricity suppliers, have contributed to the electricity price spike [ , - , ]. an important policy implication of this finding is that unless the fuel input markets are workably competitive with active spot and futures trading, an electricity market reform may fail to deliver safe and reliable service at stable and reasonable prices [ ]. as a final check, we also estimated the partial-adjustment model with a time-dependent variance specification, garch( , ) [ , chapter ]; and once again we obtained estimates of a ≈ and b ≈ . acknowledgement this paper is based on our analysis of the california natural-gas markets performed in as part of an avoided cost estimation project sponsored by the california public utilities commission (cpuc). we thank the staff of the cpuc, the california energy commission, and the participating ldcs for their input throughout the project, and to three anonymous reviewers for their very helpful suggestions on an 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[ ] woo ck, olson a, horowitz i, luk s. bi-directional causality in california’s electricity and natural-gas markets. energy policy in press. table : summary and adf statistics (“*” = “significant at p = . ”) for the three spot-gas price series supplied by platts, and pair-wise correlations between a california price and the henry hub price. the sample periods are: (a) pg&e citygate - / / - / / with daily observations; (b) socal gas price - / / - / / with , daily observations; and (c) henry hub price – same as (b). pg&e citygate price ($/mmbtu) socal gas price ($/mmbtu) henry hub price ($/mmbtu) period mean ($/mm btu) std. ($/mm btu) adf statistic correl- ation mean ($/mm btu) std. ($/mm btu) adf statistic correl- ation mean ($/mm btu) std. ($/mm btu) adf statistic full sample . . - . * . . . - . * . . . - . * before the electricity crisis . . - . * . . . - . * . . . - . * during the electricity crisis . . - . * . . . - . * . . . - . after the electricity crisis . . - . . . . - . . . . - . * table a. maximum-likelihood estimates under alternative orders of the autoregressive (ar) process for the pg&e citygate daily price regression. the sample period is / / - / / , with daily observations. the t statistics are in parentheses and “*” = “significant at p = . ”. coefficient first order second order third order fourth order f = la . ( . ) . ( . ) . ( . ) . ( . ) k . ( . ) . ( . ) . ( . ) . ( . ) k . ( . )* . ( . ) . ( . )* . ( . )* g = lb . ( . )* . ( . )* . ( . )* . ( . )* h = - l . . )* . ( . )* . ( . )* . ( . )* r . ( . )* . ( . )* . ( . )* . ( . )* r . ( . )* . ( . )* . ( . )* r - . (- . )* . ( . ) r - . (- . )* root-mean-squared error . . . . total r . . . . log-likelihood (llh) at convergence - . - . - - . llr ratio test of h : ar( ) against h : ar(j > ): χ statistic with d.f. = j - * * * akaike information criterion (aic) adf statistics for the unit-root test on the regression residuals - . * - . * - . * - . * table b. testing h : α = and h : β = . the bounds are those of a % confidence interval. basis differential (a in $/mmbtu) optimal hedge ratio (b) order of ar process estimate standard error lower bound upper bound t-stat. to test h : α = estimate standard error lower bound upper bound t-stat. to test h : β = . . - . . . . . . . - . . . - . . . . . . . - . . . - . . . . . . . - . . . - . . . . . . . - . table a. maximum-likelihood estimates under alternative orders of the autoregressive (ar) process for the socal gas daily price regression. the sample period is / / - / / with , daily observations. the t statistics are in parentheses and “*” = “significant at p = . ”. coefficient first order second order third order fourth order f = la - . (- . ) - . (-. ) - . (- . ) - . (- . ) k . ( . )* . ( . )* . ( . )* . ( . )* k . ( . )* . ( . )* . ( . )* . ( . )* g = lb . ( . )* . ( . )* . ( . )* . ( . )* h = - l . ( . )* . ( . )* . ( . )* . ( . )* r . ( . )* . ( . )* . ( . )* . ( . )* r - . (- . ) - . (- . )* - . (- . )* r . ( . )* . ( . )* r - . (- . ) root-mean-squared error . . . . total r . . . . log-likelihood (llh) at convergence - - - - llr ratio test of h : ar( ) against h : ar(j > ): χ statistic with d.f. = j - * * akaike information criterion (aic) adf statistics for the unit-root test on the regression residuals - . * - . * - . * - . * table b. testing h : α = and h : β = . the bounds are those of a % confidence interval. basis differential (a in $/mmbtu) optimal hedge ratio (b) order of ar process estimate standard error lower bound upper bound t-stat. to test h : α = estimate standard error lower bound upper bound t-stat. to test h : β = - . . - . . - . . . . . . - . . - . . - . . . . . . - . . - . . - . . . . . . - . . - . . - . . . . . . fig. . natural-gas pipelines and supply basins in western north america. major supply basins serving california include the western canadian sedimentary basin, serving northern california, the san juan, permian and anadarko basins, serving southern california, and the rocky mountain basin, serving both. source: california energy commission. $ $ $ $ $ $ $ jul- jan- jul- jan- jul- jan- jul- jan- jul- jan- jul- $/ m m b tu henry hub socal gas pg&e citygate fig. . daily spot natural-gas prices for henry hub, socal gas, and pg&e citygate, july to july . source: platts. $ $ $ $ $ $ $ $ $ jan- jul- jan- jul- jan- jul- jan- jul- jan- jul- $/ m w h sp np fig. . daily peak period ( : – : , monday-saturday) bilateral electricity prices for sp (southern california) and np (northern california). source: platts. ($ . ) ($ . ) ($ . ) ($ . ) $ . $ . $ . $ . $ . oct- jan- apr- jul- oct- jan- apr- jul- oct- $ pe r m m b tu socal gas pg&e citygate fig. . settlement prices ($/mmbtu) of nymex basis swaps contracts on / / for pg&e citygate (october to october ) and socal gas (october to december ). source: new york mercantile exchange. e d i t o r i a l special issue: current status of bioenergy research don-hee park • sang yup lee published online: february � springer-verlag berlin heidelberg due to our increasing concerns relating to climate change and limited fossil resources, the bio-based production of chemicals, fuels, and materials has been drawing much attention worldwide. the korean government announced ‘‘low carbon, green growth’’ as the most important national agenda in . it is believed that biotechnology will be playing increasingly important roles in achieving ‘green growth’ or growth with minimal environmental impact, throughout the world. the bioenergy korea conference international symposium was held on – april in gwangju, korea [ ]. this special issue contains selected papers among those presented at the conference. the topics covered include, but are not limited to, biomass cultivation, biomass pretreatment, and biomass conversion in the field of bioenergy. also, several papers on general enzyme technology and bioconversion processes are presented. as the field of bioenergy is rapidly growing from traditional forms of bioethanol and biodiesel production to more advanced biofuel production, it is expected that new bio- technologies will continue to emerge over the coming years. most of the papers in the special issue are contributed by korean biotechnologists, and thus, will provide readers with a glimpse of research activities relating to bioenergy which are current in korea. this year’s symposium had a particular focus on bioprocessing aspects of bioenergy. we currently face a great challenge as we attempt to move toward a sustainable biofuel based society, while not compromising economic stabilities. we, biotechnologists, will be a key player in instigating and overseeing this transition by providing solutions for the cost-effective production of biofuels as well as the realization of sustainable bio-based chemical industries. we would like to end by thanking all contributors to this special issue, as well as the anonymous reviewers who kindly provided their comments toward the improvement of the manuscripts. we expect that a further special issue covering state-of-the art advancements in bioenergy research will be published in the future. we hope that you will enjoy reading the papers presented in this special issue. the international symposium was an international academic conference held simultaneously with new recycled energy exhibition of sweet fair , which was held by the kimdaejung convention center in gwangju, korea. since its inauguration in , this was the fifth international event of the bioenergy conference and we were immensely honored to have the event held within gwangju. in addition, we would also like to offer our great appreciation to the chairman of the advisory committee, professor young je yoo of seoul national university, and to the advisory members, members of organizing committee, professor eunki kim of inha university and members, for their services in the planning section. the success of this conference was undoubtedly due to their dedication and cooperation. d.-h. park (&) department of biotechnology and bioengineering, interdisciplinary program of graduate school for bioenergy and biomaterials, chonnam national university, gwangju, republic of korea e-mail: dhpark@chonnam.ac.kr s. y. lee department of chemical and biomolecular engineering, kaist, daejeon, republic of korea e-mail: leesy@mbelmail.kaist.ac.kr bioprocess biosyst eng ( ) : – doi . /s - - - the international symposium invited high profile speakers with foreign speakers from countries and domestic speakers. we offered our special welcome and appreciation to president joon-hyun lee of korea institute of energy technology evaluation and planning, korea, ceo and president joon han kim of posco research institute, korea, prof. tae hyun kim of iowa state uni- versity, dr. jin-suk lee of korea institute of energy research, korea, dr. sang-soo kwak of korea research institute of bioscience and biotechnology, korea, director kwang geun park of bioenergy crop research center, korea, director hyungjin kim and chief chang-hoo lee of korea energy management corporation, korea, and second day speakers; director soon-chul park of korea institute of energy research, korea, distinguished prof. sang yup lee of kaist, korea, prof. choul-gyun lee of inha university, korea, prof. dehua liu of tsinghua university, china, prof. jin-ho seo of seoul national university, korea, emiritus prof. b.c. pillai of karunya university, india, prof. bambang prasetya, the deputy of life science indonesian institute of science, indonesia, prof. byung gi kim of seoul national university, korea, prof. joseph auresenia of de la salle university, philip- pines, prof. jian-jiang zhong of shanghai jiao tong uni- versity, china. prof. jau-yann wu of i-shou university, taiwan, prof. yoon young lee of auburn university, usa, dr. gilberto silber schmidt of brazilian agricultural research corporation, embrapa, brasil, dr. gi-wook choi of changhae ethanol co., ltd, korea, prof. seung wook kim of korea university, korea, prof. hyung joon cha of pohang university of science and technology, korea, dean tsogbadrakh mishig-ochir of national university of mongolia, mongolia, prof. man bock gu of korea university, korea, prof. sungju ahn of chonnam national university, korea, and dr. siswa setyahadi of pusat tek- nologi bioindustri-bppt, indonesia. in addition, we wish to appreciate for those speakers who made presentation of research results on posters. the posters presented on this international symposium was in the fields of bioenergy, molecular biology, biotechnol- ogy, and white and green biotechnology that it was pub- lished on international journal of springer’s bioprocess and biosystems engineering as special coverage. we thank dr. dirk weuster-bolz as the editor in chief of the journal. this symposium was an academic conference, which focused on alternative academic and technical viewpoints of overcoming the emerging global energy crisis. based on these efforts, we were able to formulate further interna- tional collaboration and to establish a number of creative projects for future endeavors. recently, all countries are becoming more dedicated toward the discovery of green growth opportunities for future economic development. green growth has been shown to be undertaken through all aspects of human lives. great examples were shown alongside their current applications within several fields, including bioenergy, carbon market, environmental indus- try, and industrial biotechnology. reference . park d ( ) proceeding of bioenergy korea conference international symposium. chonnam national university, gwangju bioprocess biosyst eng ( ) : – 	special issue: current status of bioenergy research 	reference neuromancer: the cultural logic of late fossil capital? powering the future: energy resources in science fiction and fantasy how to cite: bellamy, br neuromancer: the cultural logic of late fossil capital? open library of humanities, ( ):  , pp.  – , doi: https:// doi.org/ . /olh. published: september peer review: this article has been peer reviewed through the double-blind process of open library of humanities, which is a journal published by the open library of humanities. copyright: © the author(s). this is an open-access article distributed under the terms of the creative commons attribution . international license (cc-by . ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. see http://creativecommons.org/licenses/by/ . /. open access: open library of humanities is a peer-reviewed open access journal. digital preservation: the open library of humanities and all its journals are digitally preserved in the clockss scholarly archive service. https://doi.org/ . /olh. https://doi.org/ . /olh. http://creativecommons.org/licenses/by/ . / brent ryan bellamy ‘neuromancer: the cultural logic of late fossil capital?’ ( ) ( ): open library of humanities, doi: https://doi.org/ . /olh. powering the future: energy resources in science fiction and fantasy neuromancer: the cultural logic of late fossil capital? brent ryan bellamy trent university, ca bbellamy@trentu.ca this paper develops a take on the cultural moment of the long energy crisis ( – ) through two popular science-fiction texts. it divides the period in two: ‘oil shock’ and ‘oil glut’. further periodizing fredric jameson’s intervention into the discussion of postmodernism and his successive naming of postmodernism as the cultural logic of late capital within this framework of crisis, i ask what might be said about postmodernism in light of this moment of fossil-fuelled turmoil in the global system. my essay has two poles each located in a text from the period: isaac asimov’s essay ‘the nightmare life without fuel’ ( ) and william gibson’s neuromancer ( ). from oil shock to oil glut, this paper uses patricia yaeger’s and graeme macdonald’s work on the concept of an energy unconscious in order to begin elaborating the cultural logical of late fossil capital. https://doi.org/ . /olh. mailto:bbellamy@trentu.ca bellamy: neuromancer fossil capital, in other words, is self-expanding value passing through the metamorphosis of fossil fuels into co . it is a triangular relation between capital, labour, and a certain segment of extra-human nature, in which the exploitation of labour by capital is impelled by the consumption of this particular accessory. but fossil capital is also a process. it is an endless flow of successive valorisations of value, at every stage claiming a larger body of fossil energy to burn. one could think of it as the biophysical shadow of marx’s general formula of capital, coming to the forefront only at unexpected biospheric dusk (malm, : , emphasis in original). if one were to update the opening of fredric jameson’s postmodernism, or, the cultural logic of late capitalism today, one might start by adding to the litany of endings that constitute postmodernism. jameson’s list reads ‘the end of ideology, art, or social class; the “crisis” of leninism, social democracy, or the welfare state, etc. etc.’ ( : ). the inverted millenarianism of this list appears culturally, economically, and politically bound. it seemed, at the time of writing, that one had to insist history had indeed not ended and historical materialism was more pertinent than ever as a method of understanding and addressing social ills. in the current moment, the question of futurity is now characterized by atmosphere, global temperature, and science as well. today, jameson’s list would certainly include the end of the holocene—a real end, to be sure, but one that sees the nature-culture dyad firmly shoved aside after the realization that humanity has fully entered an era of ‘culture all the way down’—climate included—at least on the planet earth. whether dated to the dominance of james watts’ steam engine in mid-nineteenth century, as in andreas malm’s fossil capital: the rise of steam power and the roots of global warming ( ); or to what has become known as ‘the great acceleration’ of the mid-twentieth century (steffen, et al., ), critical thinkers tie the end of the holocene to humanity’s changing energy habits. yet it was not until the s that people began to register the massive change in energy-use patterns of humans, particularly in the first world. in a speech to the pensacola area chamber of commerce, admiral hyman g. rickover described the magnitude of the shift from bellamy: neuromancer renewable energy to nonrenewable energy sources, noting that in , ‘fossil fuels supplied % of the world energy; men and animals %. by the percentages had reversed themselves, % coming from coal, oil, and natural gas, % from water power, and only % from the labour of men and animals’ (qtd. in sobel, : ). however, the aim of this article does not lie in looking too far back into history, for we already find ourselves in a fully industrialized future not of our own making. rather than the origins of fossil capitalism i turn to the early years of the long downturn; to the decades of energy crisis and oil glut that provide the immediate background of jameson’s analysis of the postmodern. if the ends enumerated by jameson hint at the formation of a particular cultural logic, might the dominance of fossil fuels and the end of the holocene accept similar cultural periodisation? how might one begin to describe the cultural logic of late fossil capital? research on energy in the humanities has already sought inspiration from a dialectical approach to cultural forms. recent scholarship has identified, with a certain jamesonian flourish, a vast ‘energy unconscious’. posited by patricia yaeger in an editor’s column of pmla on energy and literature ( ) and elaborated by graeme macdonald ( ), such a concept attempts to name the unarticulated cultural logic whereby fossil fuels permeate human life yet remain unintelligible, though embedded across a whole range of practices. if ideology in marxist parlance names a problem rather than addressing false consciousness, bad thought, or worldview, then the term ‘energy unconscious’ names the very pivot around which materiality, sociality, and culture find common machination. in this passage, yaeger provocatively elaborates an extension and development of jameson’s ‘political unconscious’: following jameson, we might argue that the writer who treats fuel as a cultural code or reality effect makes a symbolic move, asserts his or her class position in a system of mythic abundance not available to the energy worker who lives in carnal exhaustion. but perhaps energy sources also enter texts as fields of force that have causalities outside (or in addition to) class conflicts and commodity wars. the touch-a-switch-and-it’s-light magic of electrical bellamy: neuromancer power, the anxiety engendered by atomic residue, the odor of coal pollution, the viscous animality of whale oil, the technology of chopping wood: each resource instantiates a changing phenomenology that could re-create our ideas about the literary text’s relation to its originating modes of production as quasi-objects. ( : – ) yaeger’s dialectical move here opens up the possibility of a methodological revision of how researchers interested in the intersection of cultural forms, fossil fuels, and socially-just futures periodize historical development. to put it in the form of a question, i would ask, ‘how might a critic go about properly exploring and expressing the relation between energy sources and cultural milieu?’ in light of this question, my essay attempts to demonstrate how such an analysis might operate alongside jameson’s argument about postmodernism. i focus in particular on the difficulty and promise of coming to terms with what can be described as the cultural logic of late fossil capitalism. this aim requires a closer consideration of the world of fossil fuels during the decades surrounding the publication of jameson’s ‘postmodernism’ essay—the s and s—and in particular their relationship to science fiction (sf), a mode of writing which jameson has often elevated as having the ‘representational means’ to designate the ‘unrepresentable totality’ ( : ). graeme macdonald’s sfra pioneer award-winning essay, ‘improbability drives’ takes up yaeger’s concept of an energy unconscious and runs with it. like jameson, macdonald posits sf as a genre ‘best placed to advance our understanding not only of present and future energy crises but also the manner in which we (fail to) envisage and conceive energy as a matter for culture’ ( : ; cf. ghosh, ). macdonald makes quick work of anyone, critics or otherwise, who dismiss sf as a site to understand energy culture: the fact that future fuel or hypothetical power sources are or may be entirely ‘made up’ can in fact provide a useful vision, a starting jolt to think here, the unrepresentable totality jameson refers to is not fossil capital, but financial capital, or what he calls ‘one of the most original dimensions of late capitalism’ ( : ). bellamy: neuromancer of alternatives to the inherent flaws (and impressive prowess) of our carbon- driven system and the hegemonic energy ontologies it reproduces. any cynical response that recognizes the fuel of sf as purely fictive denies the place of impossibilist visions as potential solutions to present and projected ecological crisis. ( : ) macdonald situates his extensive reading of sf vis-à-vis energy in a monumental re-narration of the opening of star wars ( ), which elaborates the dynamics of resource and empire captured in the opening shot of the film where a star destroyer chases down the corellian corvette tantive iv. through this reading, macdonald provides a lucid framing of what is at stake in reading sf for energy: to see the star wars opening scene from a petro-perspective, then, is to perceive its rendition in part realized and contextualized by oil, not only in modern cinema’s production process, from location trucks to special effects labs to film stock, but also as a film conceived and consumed in the volatile climate of a mid- s america that had been shaken by the tectonic shifts that the oil shocks created in the world-system. ( : ) macdonald’s point is that sf provides an opportunity to realize the predicament humanity is in in time to intervene. yet, there have been plenty of warning signs. in postmodernism, jameson uses george lucas’ american graffiti ( ) as the prime example of what he calls ‘nostalgia films’. this argument has the aura of fossil fuels about it—one might posit that this film, a whole swath of b-grade trucker films after it, and star wars too respond to the s shortfall of oil production in the us by looking back longingly to the energy abundance of the s. gerry canavan aptly outlines the impasse of futurity that attends fossil capital. in his essay ‘retrofutures and petrofutures: oil, scarcity, limit’ canavan writes that ‘[i]n the era of oil ontology, i owe this point to caleb wellum who presented a paper on this topic at petrocultures : the offshore titled ‘“keep your eyes on the road and the foot on the pedal”: s american car films and an energy imaginary in crisis.’ bellamy: neuromancer oil becomes synonymous with progress, even with the future itself’ ( : ), but demonstrates this as a retrograde form of futurism, bound up with the concisely formulated truth that ‘[o]il got us here, but oil can’t get us out’ ( : ). yaeger, macdonald, and canavan thus set the stage for a closer examination of fossil capital in specifically jamesonian terms by demonstrating the capacity of critical theory and sf to engage the cultural and environmental dimensions of energy. by its multinational phase globally and the beginning of its financial phase in the us in the s and s, capital accumulation had become a thoroughly fossil- fuelled endeavour. thus, any insights about late capital ought to hold water for an elaboration of late fossil capital. my contribution here will be to insist, alongside macdonald and canavan, that sf is crucial, as both cipher and symptom, to the endeavour of decoding the energy unconscious. i begin with an assessment of the oil crisis through an essay written in by isaac asimov that thinks about fuel explicitly. then i develop a reading of william gibson’s neuromancer ( ), a novel that only registers fuel implicitly. the different approaches required by the overt energy text (asimov) and the covert one (gibson) bear out in part what makes energy analysis a rich and necessary practice for the aim of imagining energy transition. together asimov’s and gibson’s texts speak to the ‘changing phenomenology’ of energy culture described by yaeger. after analysing both texts, i return to a section on technology from postmodernism in order to read it for traces of its own energy unconscious. to reiterate, my abiding aim in this essay is to model a dialectical approach for energy critique as a method for science-fiction studies and a critical tool for mapping the cultural logic of fossil capital. such an approach might just be able to register the way the tools of science fiction studies, and literary analysis i have selected this novel specifically because of jameson’s own claims about it as an ur-text of postmodernism: ‘[postmodern sublime narratives] have only recently crystallized in a new type of science fiction, called cyberpunk, which is fully as much an expression of transnational corporate realities as it is of good paranoia itself: william gibson’s representational innovations, indeed mark his work as an exceptional literary realization within a predominantly visual or aural postmodern production’ ( : ); and ‘[t]his is the place to regret the absence from this book of a chapter on cyberpunk, henceforth, for many of us, the supreme literary expression if not of postmodernism, then of late capitalism itself’ ( : ). bellamy: neuromancer more generally, are profoundly suited to detecting and addressing the entangled relationship of the mode of production, energy regimes, and cultural texts. the s, scarcity, and asimov in the us, an energy shortage preceded the energy crisis (sobel, : ). in the rising levels of energy consumption and stagnating energy production created an energy gap. the gap widened in —nixon described the moment as an incipient ‘energy crisis.’ to make matters worse, catastrophe followed in the wake of the mounting crisis: on february a greek tanker, the delian apollon, spilled nearly , gallons of crude in tampa, florida; on april an oil slick in alaska was reported; and on september th the irving whale sank just off the coast of new brunswick spilling , gallons of oil (sobel, : ). in the shadow cast by rising oil prices and in response to us policy on the middle east, on october , the organization of arab petroleum exporting countries (opec) revised their production and distribution of oil resources in order to influence the us, especially with regard to policy on israel. fuel prices in the us and around the world soared ever higher—the price of oil went from $ /b to $ /b. the us responded by lowering the speed limit and rationing gasoline. in time magazine asked asimov to imagine an ‘energy-poor society’ (asimov, : ) that could plausibly come to exist by the end of the th-century. this task marks a major shift in asimov’s writing. gerry canavan differentiates between his earlier works—with all their atomic-utopian hope—and the piece he would pen for time, ‘the nightmare life without fuel.’ asimov’s i, robot ( ) for example, features an african atomic age utopia that stands out from other world powers for having undeveloped fossil fuel reserves. his foundation novels ( , , and ) project a galaxy that has long since moved past fossil fuels, and his time-travel novel the end of eternity ( ) features characters shocked to learn that they must use automobiles to get around. canavan argues that ‘asimov’s sidelong references to oil and his repeated insistence on oil’s absence as a marker of human progress are ‘the term “energy crisis” did not appear in american political debate until … the summer of ’ (mitchell, : ). bellamy: neuromancer unique to the period only insofar as he bothers to mention the existence of oil at all’ ( : ). perhaps asimov’s reputation as a thinker of energy-plenty futures landed him the time gig. ‘the nightmare life without fuel’ is extrapolative. the essay looks twenty years into the future—to and a world without fossil-fuel reserves. the essay operates through a second person address, interpellating the reader thus: ‘you’ll have to walk to work again’ ( : ). it features the rise of demolition workers—a new common trade for labourers. asimov writes, ‘the fading structures of a decaying city are the great mineral mines and hardware shops of the nation’ ( : ). no longer able to power the machinery required to extract resources from the earth, americans turn to their built structures for necessary components. the life without fuel is one characterized by recycling and scavenging from the high-carbon structures of the past. asimov works through the practical question of what might be kept running. ‘what energy is left cannot be directed into personal comfort … and then of course energy must be conserved for agriculture’ ( : ). in this imagined future, car factories only produce and maintain agricultural machinery, people accept no light in the evening, and can find ways to stay warm on their own in the winters, but they cannot go hungry for long. moreover, asimov convincingly explains why people stopped using cars: ‘any automobile that dared show itself on a city street was overturned and burned … cars just vanished and became part of the metal resource’ ( : ). though this seems a dire bit of catastrophism, the future is not all bad. asimov’s speaker frames the advantages of this world through what the newspapers have to say about them: ‘the air is cleaner and there seem to be fewer colds … the crime rate had dropped … policemen are back on their beats. more important, the streets are full. legs are king in the cities of , and people walk everywhere far into the night … the suburbs were born with the auto, lived with the auto, and are dying with the auto’ ( : – ). to those critical of petroculture’s environmental impacts, clean air and walking for transport seem like desirable future outcomes; while, looking back from the bellamy: neuromancer violently securitized present, the thought of more police on the street is not so attractive. one could surmise that the crime rate has dropped as officers have had to give up their cruisers (without the depersonalizing filter of the automobile, officers on the beat are much more likely to know the people in the community). on a national level, armies are gone as ‘no one can afford to keep those expensive, energy- gobbling monstrosities’ ( : ). equating powering-down with peace, asimov effectively presents a relatively utopian vision of the world. asimov’s essay reads more like notes towards a story than a fully elaborated thought experiment. for instance, a checklist quickly writes off energy options: ‘[c]oal is too difficult to dig up and transport to give us the energy in the amounts we need, nuclear fission is judged to be too dangerous, the technical breakthrough toward nuclear fusion that we hope for never took place, and solar batteries are too expensive to maintain on the earth’s surface in sufficient quantity’ ( : ). the essay is remarkable for its capacity to construct a viable storyworld in such a short format: foreign policy and social reproduction are included in his vision, but they are not as clearly thought through as energy and infrastructure. though, during the actual crisis, americans did not start stripping buildings for materials, the dire affect of this piece—‘[e]nergy continues to decline, and machines must be replaced by human muscle and beasts of burden’ ( : )—seems to capture quite clearly the feeling of the s, which was the first decade in us history when the consumption of energy outpaced its domestic production (sobel, : ). the essay’s form and its subject matter make asimov’s thought experiment about an energy-transitioned future an explicit one. the honed tools of jameson’s symptomatic reading and yaeger’s exposition of unconscious signs of energy are not required here. the explicit-ness of asimov’s writing is built on the basis of not have enough oil; the essay’s storyworld is still oil-ontological, in canavan’s terms. one can clearly make out that asimov posits a set of conditions and then extrapolates two trends. i have already been elaborating the first. its temporality is more immediate. the second takes a longer view of what an energy-poor world might eventually come to look like: bellamy: neuromancer energy continues to decline, and machines must be replaced by human muscle and beasts of burden … where will it end? it must end in a return to the days before , to the days before the fossil fuels powered a vast machine industry and technology. it must end in subsistence farming and in a world population reduced by starvation, disease and violence to less than a billion ( : ). asimov’s conclusion seems forced from the little speculative evidence he provides. it certainly fits with canavan’s assessment of the essay as a whole as a retrofuture—a civilizational regression that imagines the only way forward is to return to a previous historical epoch. yet, ‘the nightmare life without fuel’ does have unintended lessons to offer. sites of extraction are ephemeral, as history has borne witness. so are pipelines. while sites of extraction pop up and close down, leaving ghost towns and depleted reservoirs behind, refineries remain where they are built. for fossil capital in full swing, they just cost too much to demolish. yet, asimov’s time piece suggests a prudent way to approach the hulking infrastructure of fossil capital: with a demolition crew. ‘the nightmare life without fuel’ is easily read in terms of its relation to energy crisis, which informs both its subject and historical context, yet it is crucial to remember that energy scarcity is only scarcity in relation to certain energy demands. now, in an era of technological development and offshoring, of just-in-time production and individuated automobility energy demand has never been higher. when energy runs on oil, oil runs everything. in living oil, stephanie lemenager describes the energy industry’s culture of abandonment, ‘partial removal, or toppling’ of oil and gas pipelines in the vernacular as ‘reefing’ ( : ). refineries, such as those in philadelphia, pa are too expensive to shut down and they have been open since oil was discovered in titusville (hein, ). for offshoring and just-in-time production see harvey, . peter freund and george martin note in their ecology of the automobile ‘[t]he ascendance of the private passenger auto as a dominant mode of transport, along with the fact that this mode is held to be part of a global model for development, represents a major triumph of twentieth century capitalist production’ ( : ). bellamy: neuromancer the s, energy glut, and neuromancer if the s saw a crisis in the world supply of oil, the s saw the inversion of that crisis. in ‘the energy crisis is over … again’, energy policy analyst john p. weyant writes that as of there was already ‘abundant evidence of chronic world oversupply of oil,’ and he ties this to the fact that oil consumption fell from million barrels a day (mbd) in to near mbd in (weyant, : ). the crisis of the s gets murkier when one also considers government policy and manufacturing. the thicket of us energy policy presented a dense problem for those looking to manage the crisis from the government side, because, as joseph s. nye jr. suggests, it is ‘far easier to fund the defence budget than the strategic petroleum reserve and far easier to cooperate in nato than in the international energy agency (iea)’ ( : ). meanwhile, in a paper in energy policy, walter goldstein gets at the heart of a mounting contradiction in production. he claims that ‘more industrial products were manufactured and more energy consumed in than in any previous year’ ( : ). unlike the high fuel costs of energy crisis, the oil glut presents a new set of problems and produces a different set of assumptions. in this moment prices become tied to the market, rather than governments and price-setters, and volatility reigns. moreover, the apparent abundance produces a sense of security in the energy-rich future. rather than providing a moment for energy transition away from fossil fuels, the oil glut of the s ensured an entrenchment of fossil capital, a redoubling of investments in the oil sector, and a tightening of petroleum’s grip on the shape of the future. unlike asimov’s bleak, retrospective outlook, sf authors write from a different set of conditions in the s. to read william gibson’s debut novel neuromancer today one can get the sense that he was largely describing the same present as goldstein, nye, and weyant. in both the novel and the real world energy-washed industries these figures are for the first and third world. weyant has not included second-world consumption figures. matthew huber ties the volatility in the price of oil to the opening of crude-oil futures for trade on the new york mercantile exchange in under ronald reagan ( : ). bellamy: neuromancer pump out commodities, the development of electronics complexifies, and world population climbs. let me describe the situation in gibson’s novel. banished from cyberspace, gibson’s protagonist case begins the novel psychically caught between its two cityscapes, a state of exile that aligns in illuminating ways with jameson’s diagnosis of postmodern alienation in the modern city: a year later and [case] still dreamed of cyber space, hope fading nightly. all the speed he took, all the turns he’d taken and the corners he’d cut in night city, and still he’d see the matrix in his sleep, bright lattices of logic unfolding across that colorless void … the sprawl was a long strange way home over the pacific now, and he was no console man, no cyberspace cowboy. just another hustler, trying to make it through. but the dreams came on in the japanese night like livewire voodoo, and he’d cry for it, cry in his sleep, and wake alone in the dark, curled in his capsule in some coffin hotel, his hands clawed into the bedslab, temperfoam bunched between his fingers, trying to reach the console that wasn’t there. (gibson, : ) on one hand, this passage explores chiba city through a drug addled stupor that stumbles down the twists and turns of the layered forms of so many film-noir depictions of the city, framed by the now classic opening line description, ‘the sky above the port was the color of television, tuned to a dead channel’ (gibson, : ). on the other, the promise of cyberspace—a mappable system of logic, which offers the possibility of finding purchase on the present. case’s eventual return to cyberspace and the challenges he faces there act out a sort of wish fulfilment—with the right techniques and technologies, an individual agent could not only determine where they are, but how to act in the face of that knowledge. gibson’s novel addresses the same historical problematic as jameson’s postmodernism essay: the complexity of history and the unmappable present in late capitalism for the still-modern subject. gibson may very well have invented the term ‘cyberspace’. regardless of its specific origins he certainly did bring the term into the popular imagination as with the genre-term ‘cyberpunk’ (a term first used by bruce bethke for a short story title in ) (higgins and duncan, : ). bellamy: neuromancer gibson’s cyberpunk science fiction encounters the same problematic jameson’s theory identifies, even if it does so with the bleary, red eyes behind a strung-out console jockey’s ambitions. to start thinking about the energy imaginary of neuromancer, one might recall the modes of transport that characters use in the novel. in chiba city, they travel mostly by foot. in the boston-atlanta metropolitan area, otherwise known simply as ‘the sprawl,’ they rely on trains to whip them from boston to new york. then, in istanbul, case and molly ride a self-driving, speaking car. ‘the mercedes’ talks to them, describing their location and the sights ( : , , and ). gibson extrapolates a vision of the future of automobility that, from the vantage of the present, seems like it must rely on extensively mapped terrain with a vast overlay of information— consumer gps in the s. later, they employ a shuttle to launch them into space and the marcus garvey and the babylon rocker to transport them to the space station freeside. throughout the book, they ride planes from continent to continent—japan to the usa, the usa to turkey. the train and even the car could conceivably be electric, but the jets and the spaceships would seem to require some form of fuel. the point in reading a text for its fuel signifiers should not be to determine whether the fiction has given up fossil fuels, rather one might use the survey of transportation to begin an inquiry into how energy gets taken for granted and what this revelation says about their cultural imaginary. indeed, the point here is that the energy unconscious is, indeed, unconscious. what if, following herbert sussman’s argument about gibson and bruce sterling’s the difference engine ( ), one was to read neuromancer not as a science-fiction novel but as a novel of alternative-history? what if, taking a cue from gibson and sterling’s reinvention of charles babbage’s steam-powered analytic engine—with its ‘thousands of clockwork gears and yards of punched paper’ (sussman, : )— one were to locate the point of divergence in neuromancer not in a science-fictional novum of cyberspace but in the invention of an energy regime capable of fuelling such a demanding electronic endeavour? put otherwise, what happens when one considers gibson’s first novel as an alternative history where, in sussman’s words, ‘what we accept as inevitable is only contingent’ ( : )? the reading that accepts bellamy: neuromancer a world of consoles, cyberspace, jacking in, the net, and so on without asking how these components come to be powered misses a crucial development: the fictional world of gibson’s cyberpunk runs, as readers later learn, on hydrogen power and, perhaps, on nuclear power. the more obvious lesson that attends the generic difference between neuromancer and the difference engine is that cyberpunk names a bottom-up narrative set in a techno-cultural milieu, whereas steampunk names one set within a particular energy regime. as a cyberpunk novel, neuromancer reveals its energy regime only in a mediated fashion, only in glimpses of distant power plants, only in the briefest mention of hydrogen fuel cells. neuromancer offers hints that some kind of energy transition has taken place. on the way to istanbul, molly and case both look out the train’s window, ‘“it was like this when we headed to chiba,” molly said, staring out the train window at the blasted industrial moonscape, red beacons on the horizon warning airplanes away from a fusion plant’ ( : ). some technological development has taken place, similar to the one that gerry canavan attributes to the asimov of the s and s who imagined developments in nuclear power would proceed without issue. but the ‘blasted industrial landscape’ they pass by indicates that there is more to the story here than unblemished scientific progress. the narrator says, ‘the landscape of the northern sprawl woke confused nightmares of childhood for case, dead grass tufting the cracks in a canted slab of freeway concrete’ ( : ). here, the past and present overlap. this sentence describes a scene and then implies case saw it played out in his youth—a nightmare vision he sought to repress. the pitch of the shifted highway and the failed reclamation of it by the grass indicate an arrested state. though the scene reveals little more about the nuclear question, it does offer information about transport in the sprawl—the highways are not in use and have either been destroyed or left unmaintained to crumble. the narrator the novel occasionally indicates that some kind of nuclear incidents have taken place. here the narrator describes peter riviera, the illusionist armitage employs to get them into the villa straylight—the tessier-ashpool space-station fortress: ‘he was a product of the rubble rings that fringe the radioactive core of old bonn’ ( : ). like the moment on the train that implies a nuclear event, this brief mention of old bonn’s ‘radioactive core’ leaves me guessing: is the core radioactive because of an atomic bomb, a reactor leak, or is this a way of describing a nuclear energy program used by germany in the novel, which means a different incident created the rubble? the novel is not bellamy: neuromancer passes one final piece of information to the reader: ‘[t]he train began to decelerate ten kilometres from the airport. case watched the sun rise on the landscape of childhood, on the broken slag and the rusting shell of refineries’ ( : ). case and molly pass through a landscape uncannily reminiscent of philadelphia, where since oil and gas refineries have lined the schuylkill and delaware rivers. the ‘broken slag’ and ‘rusting shells of refineries’ evoke a sense that fossil fuels, whether or not they are extracted and refined elsewhere, might not be at the core of us social and economic activity in this story world, which raises the question; what is powering this world? clear on this issue. yet, in an interview, speaking about the anxieties surrounding nuclear war in the s, gibson acknowledges that upward slant of setting neuromancer after an aborted nuclear war: ‘that war was really a conscious act of imaginative optimism. i didn’t quite believe we could be so lucky. but i didn’t want to write one of those science-fiction novels where the united states and the soviet union nuke themselves to death. i wanted to write a novel where multinational capital took over, straightened that shit out, but the world was still problematic’ (wallace-wells, ). these descriptions also resonate with bruce springsteen’s ‘born in the u.s.a.’ which, like gibson’s novel, was also released in . in that song springsteen rhymes ‘shadow of the penitentiary’ with ‘gas fires of the refinery,’ and the song also describes the plight of vietnam veterans in the wake of the conflict, returning home with ‘nowhere to run to nowhere to go’—a point i make because gibson is himself famously a draft dodger, having moved to vancouver, b.c. to escape military service. according to the philadelphia energy solutions website: ‘[i]n , one year after the end of the civil war, atlantic petroleum company established its operations at point breeze along the schuylkill river below passyunk ave. four warehouses were built, and those could store , barrels ( . million gallons) of refined oil product, mostly kerosene used as lamp oil to light the homes and businesses in the growing city….atlantic also built docks and railroad trunk lines to connect with the new refineries in western pennsylvania that were established after oil was discovered in titusville, pa, in . atlantic installed its first petroleum refining units in , changed its name to atlantic refining company and soon became philadelphia’s largest employer. right after the turn of the century, atlantic introduced the first fractionating tower, which would radically alter and improve the way oil would be refined…. in , gulf was bought out by chevron, and the girard point refinery became the chevron usa philadelphia refinery’ (philadelphia energy solutions). here is a list of refineries that case and molly could have seen on their journey: conocophillips refinery in linden, nj cap bpd, or in trainer (closed), pa cap: bpd; chevron usa inc refinery in perth amboy, nj idle cap bpd; hess corporation refinery in port reading, nj cap bpd; nustar asphalt refining refinery in paulsboro, nj idle cap bpd; pbf energy refinery in paulsboro, nj cap bpd, or in delaware city, de cap bpd sunoco inc refinery in marcus hook (closed), pa cap bpd; sunoco inc (r&m) refinery in philadelphia (gerard point), pa cap bpd, or in westville (eagle point) closed, nj: cap. bpd (energy supply logistics). from the panther modern polycarbon suits down to case’s hosaka, this world is still built by oil in the form of plastics. indeed, a key word search reveals the word plastic is used times in the novel. bellamy: neuromancer in an interview, william gibson has indicated that part of the thought experiment of neuromancer was to imagine a future that was not american (wallace- wells, ). the united states is non-existent in the novel, having become little more than a network of corporate entities, while japan is obviously a key hegemonic player on the world stage. it is interesting, then, that case and molly travel to turkey. tony myers argues that in gibson’s novel, ‘turkey occupies the position of other in capitalism’s cultural imaginary’ ( : ). he quotes the novel describing turkey as ‘a sluggish country’ and situates this sluggishness as a part of its use of ‘antiquated technologies’ ( : ). but, what if the novel describes turkey in these terms because it has not yet fully transitioned away from fossil fuels? when case and molly arrive in istanbul, the narrator says, ‘the pavement was uneven and smelled of a century’s dripping gasoline’ ( : ). more to the point compare how the two mentions of hydrogen cells in the novel replay this comparison: first, in turkey, ‘[case] watched a dull black citroen sedan, a primitive hydrogen-cell conversion, as it disgorged five sullen-looking turkish officers…’ ( : ) and then in freeside, ‘condensation dribbled from the hydrogen-cell exhaust as the red fiberglass chassis swayed on chromed shocks’ ( : ). i take myers’s point, yet i would extend it. the disdain that the characters show towards turkey in neuromancer is not unlike the hypocritical attitude of north americans in recent years to the news that major chinese cities have more smoggy days per year than clear ones (even though the province of ontario in canada only stopped burning coal in the last few years). moreover, when molly and case go to catch riviera the description of the alleyway attributes the substance a life of its own: ‘the junk looked like something that had grown there, a fungus of twisted metal and plastic’ (gibson, : ). like babbage’s initial plans for the computer, the idea of the fuel cell comes from the early th century. humphry davy first demonstrated the concept in and william grove proved that breaking a hydrogen atom could produce an electric current in . since then working fuel cells have been used on tractors, in vehicles for use in outer space, and, as early as , in road vehicles. while general electric worked on developing fuel cells, in the s and s they were mostly limited to space applications. today, car manufactures are slowly beginning to sell fuel-cell vehicles commercially. these are some of the effects of smog in ontario from around fifteen years ago: ‘in , for example, the oma detailed, there were , premature deaths, , hospital admissions, , emergency room visits, and over million minor illnesses engendered by increased ontario smog levels’ (scharper, ). bellamy: neuromancer here, i find an iteration of michael ziser’s provocation about fossil capital’s global face recast in the novel to mean something sinister. ziser writes: during the same period that the production of oil was taking on a foreign and primitive cast, its consumption in the united states was becoming the site of an alternately ecstatic and apocalyptic jouissance accelerated in the postwar period by huge national investments in the interstate highway system and by the accompanying white flight to car-dependent suburbs. ( : ) ziser makes petroleum’s double character apparent: in the us oil drives exuberance and ‘apocalyptic jouissance,’ while abroad it generates machinations and cabals. neuromancer deploys a similar logic, although it implies a different, west-justifying reason for its attitude towards the middle east. in the novel, turkey is described as backwards not because of how it uses oil, but because it still uses it at all. the sprawl, though massively energy consuming, is not fossil-fuel powered—recall that ‘power, in case’s world, meant corporate power’ ( : ) even though even the metaphoric slippage that corporate power implies must also be premised on technological breakthroughs in both hydrogen cell manufacture and nuclear fission. neuromancer reflects the fossil relations of its post-opec, oil glut moment in a distorted mirror that works to justify the high-energy life of north americans even as it looks across the pacific to the rise of japan. what is clear is that, with or without fossil fuels, the world of neuromancer is energy-rich and must be dependent on a complex energy generation and distribution system. this becomes apparent when one moves from considering transport to think through the data-transfers on which cyberspace is based in the novel. when case and molly return to the sprawl, the narrator says: program a map to display frequency of data exchange, every thousand megabytes a single pixel on a very large screen. manhattan and atlanta burn gibson’s novel fetishizes japan, the county that giovanni arrighi names as the one that looked most likely to be the inheritor of the usa’s global hegemonic status in the s (see ). bellamy: neuromancer solid white. then they start to pulse, the rate of traffic threatening to overload your stimulation. your map is about to go nova. cool it down. up your scale. each pixel a million megabytes. at a hundred million megabytes per second, you begin to make out certain blocks in midtown manhattan, outlines of hundred-year-old industrial parks ringing the old core of atlanta… ( : ) this description, unlike so much of the novel, does not rely on the metaphoric to convey the intensity of data transfer in the information age. instead, it deploys real figures, telling the reader in imperative second person to map the data spatially across time. here the figurative language, ‘go nova’ and ‘cool it down,’ describes the visceral experience one might have when dialling in a meaningful visualization— something not unfamiliar to those working on data now, either in the tech industry or as researchers. as jameson puts it in a later essay, ‘[t]he distinction of neuromancer thus lies in the form itself, as an instrument which registers current realities normally beyond the capacity of the realistic eye to see, which projects dimensions of daily life we cannot consciously experience’ (jameson : ). yet, this description of data visualization needs to be placed in the technological context of . the very idea that gigabytes of data could be transferred in the blip of a second made for a startling proposition in the early days of computing, before the internet was a part of everyday life. in terms of the sheer quantity of data usage, a vast gulf separates gibson’s science-fictional internet from that of the present day. facebook, the social media giant, provides a good example of the kind of data bandwidth used in current computing. a blog post about facebook’s data warehouse claims, ‘at facebook, we have unique storage scalability challenges when it comes to our data warehouse. our warehouse stores upwards of pb of hive data, with an incoming daily rate of about tb’ (vagata and wilfong). wait. i know what a terabyte (tb) is, but i had to look up petabyte (pb). a good ol’ gigabyte (gb) is one-thousand megabytes; a tb is roughly one-million megabytes; and a pb is one- billion megabytes. to illustrate: netflix, the video streaming service, set to display in hd uses . gb per hour (‘netflix’) which is equivalent to mb per second for a single netflix user. if million people were watching netflix at a given time bellamy: neuromancer (about ten percent of total subscribers) the data transfer from netflix servers to all these users would be at a rate of about pb per second. in gibson’s terms, that is . billion megabytes, which does not even account for other social media websites, streaming services, standard browsing of the internet, cat gifs, auto-tuned political debates, or the nyse which has its own mega-high-bandwidth infrastructure. today, a visualization of the same region would involve a scale closer to pb per megapixel (a million pixels). but the point here is not to adjust gibson’s vision to our own reality; instead it is to realize that data requires and is today’s dominant form of electricity usage. to make this seem a little more manageable, i can reduce the scale. the average google search involves a comparable amount of energy as boiling a kettle of water (around kj). so, if the kind of data transfers gibson imagines in the above paragraph would require vast amounts of real-world energy, then the capacity of a novel, let alone an infographic, to figure the energy levels currently consumed by cloud computing remains unfathomable. neuromancer projects a future where cybernetics, in matteo pasquinelli’s words, ‘transforms the economy into an ecology of feedback loops,’ controlling social unrest through a marriage of ‘the turing machine with the thermodynamic engine’ ( : , cf. ). the discrepancy in data storage and energy use between gibson’s novel and the present can be read as the result of a more elegant relation between computation and social referred to as secure financial transaction infrastructure (sfto) the nyse and other exchanges, have their own communications infrastructure. ‘in a special report to the new york times entitled ‘power, pollution, and the internet’, tech reporter james glanz made public what was until then a bit of an industry secret: digital farms or warehouses require the energy output of thirty nuclear power plants because, whether in use or not, the information housed in these warehouses remains online (glanz, ). according to pierre delforge of the natural resources defence council, ‘data center electricity consumption is projected to increase to roughly billion kilowatt-hours annually by , the equivalent annual output of power plants, costing american businesses $ billion annually in electricity bills and emitting nearly million metric tons of carbon pollution per year.’ and because most electricity comes from coal, diesel, and petroleum products, the so-called immaterial economy is not only premised on, but actively motivates, the rapid expansion of an energy infrastructure now indisputably responsible for significant contributions to climate change’ (diamanti, ). ‘google said that searches are equal to a -watt light bulb burning for minutes. “specifically, we currently use about . kwh of energy to answer the average search query,” google said. “this translates into roughly . g of carbon dioxide”’ (albanesius, ). bellamy: neuromancer relations there. for in the real world, as pasquinelli argues, capitalism has instead expanded its fossil-fuel use and generates rapidly-accreting databases, ‘feeding itself on the industrial and energetic surplus that it was supposed to measure and control’ ( ). what neuromancer so nimbly yet unconsciously grasps is that fossil capital and cybernetics are two parts of a larger whole, though with information ascendant and consistent in its siphoning increasing substantial amounts of energy. here the retrograde character of asimov’s essay becomes abundantly clear: it can process what might happen in a future without fuel, but cannot imagine, in the way that neuromancer does, a cyberfossil capital future. because it cannot project that science-fictional image, it is thus unable to ask what the nightmare life without computers might look like. for instance, without climate data and weather models, how might humans know a typical storm from an atypical one? the impasse that neuromancer so vividly anticipates is one in which the tools of ecological destruction may also be the ones that make humans capable of imagining (and enacting) an energy transition. the cultural logic of late fossil capital in the first chapter of postmodernism, jameson uses technology as a placeholder for the mode of production. he describes the fetish character attendant on capitalist development as ‘an alienated power … which turns back on and against us in unrecognizable forms and seems to constitute the massive dystopian horizon of our collective as well as our individual praxis’ ( : ). jameson means human labour here, that which seems to vanish in the neon glow of the postmodern moment, but what if one were to reread this passage in terms of the vanishing of energy from the equation? one could read jameson’s words as a description of path dependency, a term that identifies techno-scientific advances with an exponentially growing dependency on the technologies developed and the amount of energy required to sustain them. this conceptual connection, from human labour to abstract energy, bridges both imagined futures discussed above. in asimov’s nightmare, fossilized urban remains and infrastructural skeletons provide resources for a desperate humanity. in gibson’s the wealth of fossil fuels in the real world contributes to the mirage of an energy-rich vision of the future, still bound to the technological dependencies and energy suck bellamy: neuromancer of late fossil capital. asimov writes explicitly about oil and futurity, gibson does so circumstantially—neuromancer cannot help but think energy in an imagined world that uses so much of it. so, in the face of my separation of them as explicitly and implicitly energy-focused, both texts bear traces of yaeger and macdonald’s energy unconscious and both constitute the ‘massive dystopian horizon’ for collective social life and ecological flourishing or dying of the earth. even alongside asimov’s and gibson’s texts, jameson’s pronouncements only hint at the formative role energy regimes play in relation to the mode of production. the possibility of detecting, and it is only a possibility, the massive electrical currents of late fossil capital lies in a dialectical reading of science fiction’s energy unconscious. for marx, the development of machines occurs as the result of the development of capital—a development considered in stages by ernst mandel in late capitalism: the fundamental revolutions in power technology—the technology of the production of motive machines by machines—thus appears as the determinate moment in revolutions of technology as a whole. machine production of steam-driven motors since ; machine production of electric and combustion motors since the s of the th century; machine production of electronic and nuclear-powered apparatuses since the s of the th century—these are the three general revolutions in technology engendered by the capitalist mode of production since the ‘original’ industrial revolution of the later th century. (mandel, : ) mandel and jameson both figure the role of fossil fuels in the development of capital. jameson goes so far as to say that his tripartite schema—realism, modernism, postmodernism—maps on to mandel’s three stages. yet postmodernism, as a distinct moment in capital’s dominant cultural logic, comes before the recognition of the energy-ecology deadlock in late fossil capital. andreas malm characterizes mandel’s long waves of capital’s development, following his later, five-part schema from long waves of capitalist development: a marxist interpretation (mandel, ): first water-powered industry ( – ), then steam-powered industry and transport ( – ), and then the electrification bellamy: neuromancer of industry, transport, and households ( – ). the fourth and fifth waves are of particular interest here. the fourth wave ( – ) is characterized by the motorization of transport and other parts of the economy with automobiles, aircraft, refineries, petrochemicals, oil, and gas; and the fifth wave ( –?) is characterized by the computerization of the economy with computers, software, telecom equipment, and microprocessors (malm, ). gibson’s novel fits between the fourth and fifth waves, and i would argue that it is precisely because of its absolute contemporaneity that it can be seen as a novel of late fossil capital. however: i am not only interested in correctly locating the real ground of neuromancer’s energy unconscious; and have sought to illuminate the deadlock of the world that fossil capital builds and the impression the latter has on how sf can imagine the future. fossil capital’s long waves rise with the charged boom of development and fall with the resounding crash of crisis. from on oil is increasingly the source of economic, social, and environmental volatility, but it also shores up capital and provides a means for continued profitability. for a time, the exponential rise in the use of fossil fuels could actually explain the delay in the fall of the rate of profit, but today it cannot. to be sure, fossil fuels are still culturally and economically dominant, not to mention environmentally catastrophic, but with the twin recognition that the holocene is over and that fossil capital is the driver of that end, humanity sits on the cusp of a different condition of ends than the one opened up in the s and that jameson and gibson so attentively tracked. i am not trying to argue that cyberpunk, or gibson’s novel for that matter, provide the form capable of grasping the cultural logic of a new global formation, but that at this ‘unexpected biospheric dusk’ (malm, fossil capital ) neuromancer provides dialectical thinking with something worth considering: the future imagined from within fossil capital pushes at the limits of what kind of energy transition is truly possible. acknowledgements i would like to acknowledge the support of the social sciences and humanities research council of canada and to thank jeff diamanti for offering comments on a draft of this paper. bellamy: neuromancer competing interests the author has no competing interests to declare. references albanesius, c how much electricity does google consume each year?, pc mag, online at: https://www.pcmag.com/article / , , , .asp [last accessed th august ]. arrighi, g the long twentieth century: money, power and the origins of our times. london: verso. asimov, i the nightmare life without fuel. in: allen, d (ed.), science fiction: the future, second edition, pp. – . new york: harcourt brace jovanovich. canavan, g retrofutures and petrofutures: oil, scarcity, limit. in: barrett, r and worden, d (eds.), oil culture, pp. – . minneapolis: university of minnesota press. doi: https://doi.org/ . /minnesota/ . . diamanti, j energyscapes, architecture, and the expanded field of postindustrial philosophy. postmodern culture, ( ). doi: https://doi. org/ . /pmc. . energy supply logistics n.d. refineries map, online at: http://www. energysupplylogistics.com/map/ [last 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/ . . https://doi.org/ . /pmla. . . . https://doi.org/ . /pmla. . . . https://doi.org/ . /pmla. . . . bellamy: neuromancer how to cite this article: bellamy, b r neuromancer: the cultural logic of late fossil capital? open library of humanities, ( ): , pp.  – , doi: https://doi. org/ . /olh. published: september copyright: © the author(s). this is an open-access article distributed under the terms of the creative commons attribution . international license (cc-by . ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. see http://creativecommons.org/licenses/by/ . /. open access open library of humanities is a peer-reviewed open access journal published by open library of humanities. https://doi.org/ . /olh. https://doi.org/ . /olh. http://creativecommons.org/licenses/by/ . / 	the s, scarcity, and asimov 	the s, energy glut, and neuromancer 	the cultural logic of late fossil capital 	acknowledgements 	competing interests 	references microsoft word - whitepaper_final_horowitz.doc a law enforcement perspective of electricity deregulation ira horowitz* warrington college of business, university of florida, gainesville, fl - , usa abstract in april , the california attorney general’s (ag) office issued a white paper that provided a “law enforcement perspective of the california energy crisis.” to complete this special issue's coverage, i summarize three aspects of that paper: notably, the deficiencies in market oversight and enforcement that left the deregulated market prone to potential abuse, the principal modus operandi that some market agents used to exploit those deficiencies without fear of retribution, and the ag’s “recommendations for improving enforcement and protecting consumers in deregulated energy markets.” * tel: + - - - ; fax: + - - - email address: ira.horowitz@cba.ufl.edu . introduction in , the california legislature enacted assembly bill (ab) under which retail electricity rates would remain subject to regulatory review by the california public utilities commission (cpuc), at least for the foreseeable future, with wholesale rates being determined by market forces [ - ]. to that end, california’s three major investor- owned integrated utilities (ious) were encouraged to divest themselves of their fossil fuel generating plants. the ious turned over control of their transmission lines to an independent system operator (iso) that would be subject to regulatory oversight by the united states federal energy regulatory commission (ferc). the iso was charged with managing the grid’s day-to-day operations, which means allocating limited network capacity, and purchasing and selling reserves and real-time energy so as to correct any minor real-time imbalances between loads and resources. separately, ab also created a wholesale spot market in which the ious must transact. established in , the california power exchange (px) served as the central market for some % of the state’s energy transactions, with the market-clearing prices determined by locational demands and supplies. the feel-good presumption behind all of this was that consumers would reap the benefits of partial deregulation and competitive spot markets. the reality of may through june , however, was an energy crisis that manifested itself in soaring wholesale electricity prices far above the capped retail rates, frequent power shortages and consequent rolling blackouts. during november through may , the coincident dramatic price increases in natural gas exacerbated the electricity problems. the px closed its doors on february , , and the responsibility to ensure competitive electricity prices for transactions other than the bilateral power agreements between ldcs and energy suppliers fell to the iso. nevertheless, the soaring wholesale prices and capped retail rates caused financial insolvency of two of the ious: pacific gas and electric company and southern california edison. san diego gas and electric was spared because of the removal of capped retail rates in mid- upon its full stranded- cost recovery. it was apparent that deregulation wasn’t working as the california legislature had intended and that something was seriously amiss. it didn’t take too long before academics and practitioners alike were offering their explanations and solutions, and for enron to become a household word - and not just in the united states. one problem in particular was that the ious could only transact in spot markets, which might tempt both large- capacity generators to withhold power when supply was tight so as to drive up the wholesale price on a virtually inelastic demand curve, and greedy marketers to devise and implement various short-term market-gaming strategies to pad their pocketbooks, to the ultimate detriment of consumers for whom adequate remedies are unavailable. in april , the california attorney general’s office (ag) entered the debate through a “white paper” [ ] that provided a “law enforcement perspective of the california energy crisis” that plagued california’s electricity and natural-gas markets. at the request of this journal's editor-in-chief, i summarize three aspects of that paper: notably, the deficiencies in market oversight and enforcement that left the deregulated market prone to potential abuse, the principal modus operandi that some market agents used to exploit those deficiencies without fear of retribution, and the ag’s “recommendations for improving enforcement and protecting consumers in deregulated energy markets.” . the deficiencies the ag identifies and details what boil down to five major failures and deficiencies in market oversight and enforcement. first, it is left to ferc to determine whether a given generator possesses sufficient market power as to adversely impact price should it choose to do so, say by withholding supply. once ferc has made a determination that a generator does not possess the requisite power, the generator is free to charge whatever prices buyers are willing to pay, and, ferc insists, the generator is immunized from retroactive refunds and antitrust actions. ferc, however, has limited expertise in antitrust and market-power issues, and has not necessarily devoted the time and effort required to make appropriate determinations in those regards. second, although electricity sellers are required to provide ferc with quarterly reports of their business transactions so that it can adequately monitor the energy markets and ensure market-based rates that would approach the competitive norms, the requirement was all too often honored in the breach. by viewing the lapses as “essentially a compliance issue” that an offending generator could rectify by filing an amending report, ferc failed to detect a plethora of instances in which participants manipulated the markets. third, generators and traders believe their pricing practices are not subject to judicial review, under the filed-rate doctrine that prevents legal challenges to filed rates that have been approved by administrative agencies such as ferc. believing that the process of reviewing all rates and terms of sale impeded the competitive process, because it kept sellers from reacting promptly to changing market conditions, ferc in the late s “drastically cut back the filing requirements for sellers transacting at market-based rates.” once a seller demonstrates that it lacks market power or has taken steps to mitigate any power that it might possess, it need only file a “market-based tariff” stating that rates will be determined by agreement of the transacting parties, and it is this tariff to which the filed-rate applies and that earns ferc’s blanket authorization. fourth, the iso, the cpuc, and the electricity oversight board (eob) also failed to exercise adequate market oversight and enforcement of state laws that are themselves of limited enforceability. finally, the security and exchange commission (sec) exempted the ious from full scrutiny under the public utilities holding company act (puhca). pacific gas & electric (pg&e), in particular, took advantage of the situation by diverting $ billion in earnings to its parent company in the face of large losses and impending bankruptcy. . exploiting the deficiencies the ag focuses on two very different ways in which the market-oversight-and- enforcement deficiencies were exploited: ( ) the raw exercise of undetected and/or undisciplined market power by merchant generators that have no franchised service territories and no legal obligation to serve retail customers; and ( ) traders gaming the market through highly complex strategies that are difficult to detect, regulate, or subject to judicial review and consequences.. in the former regard, generators withheld power from california’s markets by both reducing production for those markets and simultaneously exporting power to neighboring states, and then allowing the law of supply and demand to take effect – as it did and with predictable consequences. in the latter regard, enron in particular devised a series of marketing-gaming strategies, four of which take center stage in the ag’s report: falsely scheduling power along a congested transmission line in the expectation of being paid to reduce the load; exporting power to a willing accomplice that would resell that power for import at a much higher price; submitting “paper” offers to the iso in the day-ahead market and covering those offers at the lower capped prices of the real-time market; and scheduling energy in the opposite direction of congestion and then being paid to reduce a load that it had no intention to provide in the first place. . the key recommendations the ag makes four key recommendations, among others, to correct the deficiencies. first and foremost, there should be a codified statement to the effect that the filed- rate doctrine does not apply to market-based rates and that retroactive refunds, if justified, are available to consumers. further, and with specific regard to ferc, there should be established “written criteria for market monitoring, identification of gaming, and steps to be taken when markets fail to function properly” and a mechanism should be created “to encourage direct consumer participation” in proceedings before it. second, provide the iso with a “specific and transparent market monitoring system, with specific and enforceable standards for addressing market anomalies and abuses of market power,” along with the resources and administrative enforcement authority that would allow it to be an effective enforcer and market monitor. third, amend federal law to require ferc to cooperate with state and local investigations of any alleged misconduct in the energy markets, and to promote coordination of federal and state enforcement efforts; and consider creating a multi- jurisdictional interagency energy task force. fourth, eliminate the intrastate exemption of interstate utility holding companies from the puhca, and if the puhca is amended or rescinded, retain the oversight-and- review aspects of the law for such holding companies. . conclusion the notion of deregulated energy markets that are subject only to the discipline of competitive market forces is assuredly appealing, even though the california experience makes evident that it is somewhat naïve. the ag’s white paper argues that because such markets are particularly susceptible to market-power abuses as well as obtuse gaming strategies by unscrupulous agents, a critical aspect of the deregulation process should contain the following components: (a) the concurrent establishment of cooperating oversight bodies that have been provided with well-defined responsibilities; (b) the appropriate criteria and analytic frameworks for gauging market performance; (c) the resources to carry out their missions; and (d) the power to enforce their findings. the ultimate end is that the oversight bodies must protect consumers who are compensated for any losses that they may have suffered as the result of non-competitive acts. it is a well taken argument. reference [ ] jurewitz jl. california electricity debacle: a guided tour. electricity journal ; ( ): - . [ ] woo ck. what went wrong in california’s electricity market? energy ; ( ): - . [ ] woo ck, lloyd d, tishler a. electricity market reform failures: uk, norway, alberta and california. energy policy ; ( ): - . [ ] california attorney general’s office. attorney general’s energy white paper. sacramento, ca, . see also: http://caag.state.ca.us/publications/energywhitepaper.pdf. - .indd © nature publishing group the belief that canada is .rich in nat- ural resources is generally accepted by canadians as well as others, and is cer- tainly widely held by their neighbours south of the border. i<t is, in fact, one basis of <the usa's wish for joint con- trol of north american resources. it ·is thus interesting .to hear from a professor of geology at carleton uni- versity, f. kenneth north, that this idea is largely illusory. "canada," dr north told a ·recent conference on technology and canadian foreign re- lations at this university in ottawa, "is the only energy-deficient nation in the world which believes itself to be energy- abundant and behaves accordingly." dr north has a habit of making flat, uncompromising statements, and he has been making quite a few of them regarding canada's energy supplies in recent months. the kind of thing he told ·the carleton conference was just what he has been telling federal authorities, although there is not much evidence· that they have been listening. pe·rhaps this as because they do not want to believe him. his message is that energy supplies-particula·rly oil- have been vastly overestimated and that, regardless of what action is taken, canada faces a severe energy crisis before the end of the s. "no matter how carefully we estab- l.ish our priorities, no matter how expeditiously that conversion to other energy forms can be brought about, no matter how successful our conserva- tion measures may become, social and economic disruptions on a vast scale are inev·itable", he says. 'the united states will be a much .jess affluent and comfortable place than it has been . canadians should be wondering whether large parts of t·hei·r country might not have to be evacuated." that is pre·tty strong stuff, and the recourse of some who hea•r it is simply to recoil into their natural optimism . phi·lip h. tresize, another delegate to the carle•ton conference (organised by the norman paterson school of inte·r- national affairs), did just that. now a senior fellow at the brookings insti- tute and a former us ambassador to the oecd, mr tresize replied: "i am not impressed with the idea we're run- ning out of resources .. . i can't chal- lenge dr north, but the world is made uo of little else than raw materials, and our history has been that we've consistently found new resources. and i have no reason to believe this will not continue to the end of time ." dr nort·h had more facts than that at his disoosal. canada has always been regarded bv her american neighbours as "some kind of resource cornucopia." he said. "but canada is not remarkably rich in primary •resources in proportion to hs size. the number of really large mines .jn canada can be counted on the is canada an energy- deficient nation ? from david spurgeon, ollawa fingers of one hand, and we have no very large oil or gas fields. there are individual copper mines in chile and africa capable of producing more new copper than all canadian mines put together. many of the richest gold and silver camps are jn the western cordil- lera of the ameri·cas. "though we have % of ·the earth's land area, and more than % of its area of continental crust, we have less than % of .its conventional oi·l," said dr north . "even our vast reservoks of ~resh water are easily misrepresented. far too much of it lies on the surface jn easi.jy polluted lakes; for a land of canada's size, we are short of good subsurface aquifers because so much of our tehitory is either precambrian shield or ·impermeable igneous rock. "canada owes her outstanding mineral production to her geographic and economic relationship to the united states. we have allowed them to establish our country as their re- source hinterland. canada's gross mineml production constitutes % of our gross national product. ninety per cent of it is exported . of ah canadian exports, of all materials to all trading pa.rtners, nearly one-sixth is of minerals and fossil fuels to the united states." canada's total known remaining oil reserves represent less than months of present north american consump- tion, dr north said. the proven tar sands reserves represent for north america an extension of four years in the life of its reserves-not hundreds as many imagine. canada's total known natural gas reserves, including those j.n t·he arctic, which may never be made avai•lable , consti•tute a supply of about months at present north american rates of consumption. and the reserves of gas so far known in the mackenzie delta, after nine years of drilling, would keep the proposed -inch pipe- line filled for f years. north's pessimism extends beyond canada, howeve·r. outside the com- munist world, the rate of finding oil has shown a perceptible decli·ne since , he says, and outside the persian gulf, the heyday of which is now past, the 'free-world' has found only four basins having recoverable reserves of oil large enough to satisfy a single year's global demand . the only new basins capable of yielding prolifically are in remote or umeliable regions, chiefly offshore, and statistical probabili-ty studies show that the earth's crust is "very unlikely to possess more than a handful of pro- lific basins still to be discovered. even nature vol. june if each of these is presumed to be as rich as the alberta basin, or the north sea, we are look.ing at a quantity of new oi·l, from new regions, very much smaller than !!he quantity we have al- ready produced and consumed." this leads dr north to predict that the level of world oh production will start •to decline in about , not halfway through the st century, as many authorities maintain . similarly, he says it is statistically unlikely that north america can pos- sess more than one or two potentially proiific basins •that are still undiscov- ered . canada's rate of production must start to decline in a year or less, be- cause reserves have already been de- clining for five years and the rate of addition to reserves has be·en declining for years. "starting next year, our capa'ci.ty to provide domestic oil will decline at an average rate of , barrels a day per year. unless all demand growth can be curbed, therefore, even a new ta-r-sand plant eve·ry year would be incapable of maintaining canadian self- sufficiency in oil. by , our deficit will reach million baorrels a day . .. it is unlikely-almost inconceivable, in fact-that tar-sand production will reach even half that amount by then." such doom-saying did not impress mr tresize. if we run out of one re- source, he said, human experience teaches us that we can have confidence we will find substitutes that will do just as well. o a hundred years ago dr forel, of lausanne. has for several years been investigating what are known as the seiches of the lake of geneva . seich e is applied locally to certain oscillatory movements which are occasionally seen to occur on the surface of the lake . the phenomenon had been investigated by previous observers, among others by saussure and vaucher, who attributed the pheno- menon to variations in atmospheric pressure ; in this. fore!, who has most minutely investigated the phenomenon. a grees with them. the phenomenon is found to occur on other swiss lakes. and fore! believes it will be found in all large bodies of wa ter. indeed. he re :ognises in the seiche probabl y the most considerable and the grandest oscillatory movement which can be studied on the surfa ce of the globe. f rom nature, , ; june , 	is canada an energy deficient nation ? cerebral microdialysis: going deep into brain biochemistry for a better understanding of pathomechanisms of acute brain injury deepak kumar gupta anna teresa mazzeo department of neurosurgery, all india institute of medical sciences, new delhi, india department of surgical sciences, university of torino, torino, italy indian j neurosurg ; : – . address for correspondence deepak kumar gupta, md, department of neurosurgery, all india institute of medical sciences, new delhi , india (e-mail: drdeepakgupta@gmail.com). introduction patients with traumatic brain injury (tbi) have variable outcomes subject to intracranial hypertension, ischemia, hypotension, and various biochemical alterations. intracranial pressure (icp) monitoring is indicated in all severe head injury cases with detectable lesions by computed tomography (ct) scan of the head as it has been shown that patients with icp > mm hg have poor outcome if not subjected to medical/surgical management for intractable intracranial hypertension. despite adequate decompression for raised icp, a subset of patients remain who continue to deteriorate and have poor neurologic outcome at long-term follow-up. this is being attributed to ongoing biochemical changes in brain tissue (secondary insult/ongoing insults) even after decompressive craniectomy (dc), and this calls for the need for monitoring of brain biochemistry for understanding these changes. multimodality neurointensive monitoring is standard of care for decision making in all severe tbi cases at present in most neurotrauma units. neuromonitoring tools, such as cerebral microdialysis, may contribute to understanding the pathomechanisms of acute brain injury, provide an early warning of secondary cerebral deterioration (therapeutic window of opportunity), and help in selecting the patients most suitable to benefit from this very invasive surgical rescue therapy (►fig. ). furthermore, cerebral microdialysis can be used as a measure of the effect of dc on neurochemistry derangement and brain energy crisis jeopardizing the injured brain. cerebral microdialysis is a means to monitor cerebral biochemistry and has been in use globally in human studies for various conditions since the past two decades. the various compounds measured by cerebral microdialysis include the glucose, pyruvate, lactate, glycerol, glutamate, and urea. keywords ► cerebral microdialysis ► severe traumatic brain injury ► decompressive craniectomy ► ischemia ► mitochondrial dysfunction abstract patients with traumatic brain injury (tbi) have variable outcomes subject to intracranial hypertension, ischemia, hypotension, and various biochemical alterations. multimodality neurointensive monitoring is standard of care for decision making in all severe tbi cases at present in most neurotrauma units. neuromonitoring tools, such as cerebral microdialysis, may contribute to understanding the pathomechanisms of acute brain injury, provide an early warning of secondary cerebral deterioration (therapeutic window of opportunity), and help in selecting the patients most suitable to benefit from this very invasive surgical rescue therapy. cerebral microdialysis can be used as a measure of the effect of decompressive craniectomy on neurochemistry derangement and brain energy crisis jeopardizing the injured brain. present review discusses the cerebral microdialysis, its usefulness, and role in prognostication of severe tbis, especially in patients post- decompressive craniectomy. the authors also discuss the current consensus guidelines on usage of cerebral microdialysis in tbi patients. received june , accepted july , published online august , doi https://doi.org/ . /s- - . issn - x. © neurological surgeons’ society of india review article thieme mailto:drdeepakgupta@gmail.com https://doi.org/ . /s- - https://doi.org/ . /s- - studies on tbi patients using microdialysis have shown that injured parts of the brain contain high lactate levels corresponding to significant acidosis. cerebral microdialysis can monitor brain tissue biochemical changes bedside, continuously ( hourly) by means of a thin catheter inserted in the brain parenchyma, and dialysate thus obtained can be analyzed allowing real-time diagnosis of ongoing ischemia at bedside. insertion of microdialysis catheters has been shown to be safe in many studies available and is being used for neuromonitoring already globally in advanced neurointensive units where this facility is available. rise in lactate (acidosis) and in lactate/pyruvate ratio (lpr) has been noted in ischemic brains especially in penumbra zone in such cases, and these biochemical changes can get altered further with worsening of ischemia/hypoxia, thereby suggesting if interventions to reduce ischemia (increase of cerebral perfusion/cerebral blood flow or decreasing icp by medical or surgical means) are implemented well in time, outcome in such cases could be improved by improving local cerebral blood flow and decreasing ischemia. there is likely to be a therapeutic window of biochemical alterations preceding rise in icp/fall in cerebral perfusion pressure (cpp) in these cases, and there exists probably a time period during which early timely interventions can be beneficial. principle of microdialysis microdialysis is a minimally invasive technique in which a thin probe, with a semipermeable dialysis membrane at its tip, is inserted into the brain for continuous sampling of the brain interstitial fluid. the microdialysis catheter takes up substances delivered by the blood, for example glucose and drugs, but also substances released from the cells, for example markers of cellular metabolism. the interstitial fluid is the “cross road” of all substances passing between cells and blood capillaries. the dialysis membrane at the distal end of a microdialysis catheter functions like a blood capillary. molecules at high concentration in the extracellular fluid equilibrate across the semipermeable membrane. the enriched perfusate (i.e., the dialysate) is collected via an outlet tube and can be analyzed. chemical substances from the interstitial fluid diffuse across the membrane into the perfusion fluid inside the catheter. monitoring this compartment in the brain allows the clinician to have critical information about the biochemistry of neurons and glia and how seriously brain cells are affected by, for example ischemia, hyperemia, trauma, vasospasm, as well as various physiologic and pharmacologic interventions (►fig. a–d). depending on the availability of an appropriate analytical assay, virtually any soluble molecule in the interstitial fluid can be measured by microdialysis. most commonly, microdialysis catheter probes (molecular weight cutoff of kda, -mm membrane length, and an external diameter of . mm) are placed in the perilesional tissue. the catheter can also be placed via burr hole in patients being managed conservatively/ on contralateral side for normal control sample assays. the probes are perfused through a precision microdialysis pump with cns perfusion fluid at . to µl/min and samples collected for bedside analysis. the “recovery” of a particular substance is defined as the concentration in the dialysate expressed as a percent of the concentration in the interstitial fluid. factor affecting recovery of an analytes include perfusion flow rate, molecular weight cutoff of the dialysis membrane, surface area of the dialysis membrane (length and diameter of the probe), diffusion rate in dialysis membrane, blood flow rate, metabolism rate, and extent of tissue vascularization. in particular, measured values for interstitial products vary with perfusion rates; the lower the rate ( . µl/min), the higher the relative recovery of the molecule. concentrations of glucose, lactate, pyruvate, glutamate, and glycerol in the microdialysate are analyzed using the microdialysis analyzer. by the use of advanced neuromonitor tools, such as cerebral microdialysis, in the injured brain, the clinician is provided with a very early warning of secondary cerebral deterioration that offers the opportunity to deliver targeted therapy before irreversible neuronal damage occurs. biochemical data are more informative, if integrated with other neurophysiologic parameters commonly monitored after an acute brain injury, such as icp, cpp, mean arterial pressure (map), and plasma glucose. microdialysis as a measure of brain energy metabolism alterations, brain tissue ischemia, excitotoxicity, and neuroinflammation after tbi tbi is responsible for a complex dysfunction in brain energy metabolism. oxygen is needed for oxidative phosphorylation in the mitochondria. under normal aerobic conditions, glucose is converted to pyruvate by glycolysis and pyruvate is then metabolized in the citric acid cycle and the mitochondrial respiratory chain. intbi, shear forces and the release of free radicals and intracellular calcium lead to inactivation of mitochondrial respiration and fig. cerebral microdialysis and neuromonitoring tools offer therapeutic window of few hours before new-onset clinical symptoms. indian journal of neurosurgery vol. no. / cerebral microdialysis gupta, mazzeo the stages of the krebs cycle, leading to mitochondrial dysfunction and brain energy crisis. in fact, with insufficient oxygen delivery, neurons must rely on anaerobic metabolism of glucose for energy. during ischemia, there is a shift from aerobic to anaerobic metabolism, and pyruvate, unable to enter the citric acid cycle, is reduced to lactate, accepting electrons from nadh and so providing the nad necessary for glycolysis to continue. the extracellular reflection of these intracellular events is: reduction in glucose and pyruvate and increase in lactate and lpr. the use of microdialysis allows the manifestation of this “energy crisis” (►fig. ) to be detected and monitored over time and the effect of therapeutic intervention to be evaluated. glutamate is another small molecule measured by microdialysis that may be used as a marker of excitotoxicity, which is a proposed mechanism of secondary brain injury, mediated by massive calcium influx into brain cells via glutamate-mediated opening of neuronal calcium channels. , glutamate has been seen to be elevated - to -fold in severe primary human tbi, and in very severe secondary insults, it is correlated with herniation, hypoxia/ischemia, and poor outcome. – glycerol is a less widely reported but well-validated marker of free radical generation, bimolecular leaflet cell membrane damage, phospholipid breakdown, and consequent free-fatty acid release. this results from hypoxic/ischemic events, as well as calcium release into neurons and astrocytes, via the inactivation of protective enzymes such as peroxidase and superoxide dismutase, among others. , , cerebral microdialysis is a well-established research tool that has enormously contributed to the authors’ understanding of the derangements occurring in the acutely injured brain, as demonstrated by a rich literature after acute brain injury in humans. in a population of comatose-operated patients with secondary brain ischemia following aneurysmal subarachnoid hemorrhage (sah) and severe tbi, dizdarevic et al conducted a fig. (a) cerebral microdialysis catheter and microvial used for cerebral microdialysis. (b) microdialysis catheter as universal biosensor/blood capillary. (c) cerebral microdialysis analyzer used to monitor the values of dialysate bedside. (d) schematic picture showing principle of microdialysis with microdialysis in center collecting products of cellular metabolism from cell and interstitial fluid components from capillary by diffusion. fig. schematic representation of citric acid cycle showing energy metabolism in brain tissue. adp, adenosine diphosphate; atp, adenosine triphosphate; tca, tricarboxylic acid. indian journal of neurosurgery vol. no. / cerebral microdialysis gupta, mazzeo prospective, randomized controlled study comparing relative effectiveness of the two popular management strategies for head injury such as icp-targeted therapy with cerebral microdialysis monitoring according to the modified lund’s concept or cpp-targeted therapy. the authors found that patients treated with icp-targeted therapy with microdialysis monitoring had significantly lower mortality rate as compared with those treated with cpp-targeted therapy. patients monitored with microdialysis who had poor outcome had lower mean values of glucose and higher mean values of glycerol and lpr as compared with those who had good outcome. there was no difference in the mortality outcome between aneurysmal sahand severe tbi in thetwo groups. the authors concluded that the modified lund’s concept, directed at bedside real-time monitoring of brain biochemistry by microdialysis, showed better results compared with cpp- targeted therapy in this patient population. omerhodzić et al performed an observational prospective clinical study on the treatment and outcome of patients with sah and traumatic intracranial hemorrhage. positive correlation was found between brain interstitial glucose level and outcome at -year follow-up (when glucose level was lower, the patient glasgow outcome scale [gos] score was worse), suggesting that early initiation of appropriate therapeutic strategies to overcome cerebral ischemia and secondary brain damage eventually leads to better patient outcome. karathanou et al investigated the usefulness of cerebral microdialysis in predicting the outcomes of tbi patients and concluded that biochemical parameters analyzed using microdialysis could serve as predictor indexes of clinical outcome several months after the injury. rostami and bellander investigated the correlation of glucose levels in peripheral blood, subcutaneous (sc) fat, and extracellular intracerebral tissue in patients with severe tbi during neurointensive care. they found a significant positive correlation between levels of glucose in peripheral blood, sc fat, and noninjured brain during the initial hours but not in injured brain. they concluded that there is a good correlation between blood and adipose tissue glucose levels during initial and later time points in the neurointensive care unit whereas the correlation between blood and brain glucose levels seems to be more individualized among patients. this emphasizes the importance of using intracerebral microdialysis to ensure adequate intracerebral levels of glucose in patients suffering from severe tbi and to detect hypoglycemia in the brain despite normal levels of blood glucose. in a study to determine the relationship between the fundamental biochemical markers and neurologic outcome in a large cohort of patients with tbi, it was suggested that extracellular metabolic markers as measured by microdialysis are independently associated with outcome following tbi. furthermore, in a large population of tbi patients, bullock and coworkers demonstrated that the results of microdialysis- based neurochemical monitoring correlate with quantitation of ischemic events, as measured by a simple five-item scoring system, taking into account the occurrence of specific potentially brain-damaging events (hypoxemia, hypotension, low cerebral blood flow, herniation, and low cpp). recently, in a population of tbi patients undergoing spreading depolarization (sd) monitoring, with electrocorticography, the association of sd and neurochemical markers as measured by microdialysis were studied. the authors showed that extracellular glutamate ( µmol/l) and lactate ( . mmol/l) were significantly elevated on day in patients with sd. furthermore, glutamate and lpr progressively increased with the number of sds, exceeding the pathologic threshold for excitotoxicity (glut > ) and metabolic crisis (lpr > ). the same group also demonstrated a strong association between sd and the occurrence of secondary insults after tbi (low cpp, low map, high temperature). these results suggest sd as an important pathomechanism of secondary brain damage after tbi and confirm the role of microdialysis in the study of pathomechanism of brain injury. the role of neuroinflammation as a key pathomechanism of damage after acute brain injury has also been investigated with cerebral microdialysis. posttraumatic neuroinflammation is characterized by glial activation, leukocyte recruitment, and upregulation and secretion of mediators such as cytokines and chemokines. in particular, helmy et al demonstrated the different pattern of response in brain and peripheral blood of cytokines production and the difference in cytokines profile after recombinant human il- ra administration in a phase ii randomized control trial. , the use of microdialysis monitoring to evaluate putative neuroprotective drugs after severe tbi has been also documented in clinical trials, demonstrating the utility of this monitoring tool, not only to measure the effect of a treatment on brain biochemistry but also to detect the brain interstitial level of intravenous administered neuroprotective drugs. this can help for safer dose optimization to achieve target concentrations of putative neuroprotectant drugs for neuroprotection in future tbi studies. cerebral microdialysis usefulness in neuromonitoring after decompressive craniectomy neuromonitoring can be a measure of the effect of treatment (i.e., dc) on cerebral ischemia and hypoxia, as it relates to neurologic outcomes. the results of neuromonitoring can offer clinicians a perspective on the appropriate time window for the investigated rescue treatment – (►figs. , ). placement of catheter is desired in penumbra zone peripheral to contused brain tissue or on the same side in noneloquent area after evacuation of subdural hematoma (►fig. ). guidance of critical care management after dc, especially in those cases characterized by occurrence of a hyperemic response after the procedure, may be an important next step. in fact, postoperative derangement in cerebrovascular pressure reactivity may be present after dc and could cause malignant cerebral hyperemia, as may be seen in the operating room in the case of very high cpp. failure of restoration of brain energy metabolism resulting from a persistent energy metabolic crisis may occur, indian journal of neurosurgery vol. no. / cerebral microdialysis gupta, mazzeo demonstrated by mitochondrial dysfunction or signs of cerebral ischemia, and it clearly needs further evaluation. overall, the evaluation of the effects of dc on neurochemistry and brain oxygen delivery may contribute to a better understanding of the role of this procedure in the treatment of intracranial hypertension. gupta et al , studied a cohort of adult patients with severe tbi undergoing dc. twenty-six ( . %) patients had a favorable outcome (gos score or ) and patients ( . %) had an unfavorable outcome (gos scores – ) at months’ follow-up. all patients were managed in the neurointensive care unit with multimodality monitoring over a course of days following dc. total , hours of monitoring values of various microdialysis variables were obtained. there were no episodes of catheter insertion–induced hematoma or meningitis. in these studies, the authors demonstrated significant cerebral biochemical alterations, as detected by cerebral microdialysis. glucose there was no significant difference in mean random blood sugar (rbs) ( . vs. . mmol/l; p ¼ . ) and mean cerebral glucose ( . vs. . mmol/l; p ¼ . ) values among the good or bad outcome groups, respectively. a poor correlation between plasma and cerebral glucose for the entire cohort was noted (p ¼ . ). this suggests that brain interstitial microdialysate glucose values are not always reflective of changes in systemic glucose. a significant difference was noted in the incidence of hyperglycemia (rbs > mmol/l) and hypoglycemia (rbs < mmol/l) between the two outcome groups (p < . ). the microdialysis glucose values during the episodes of hyperglycemia or hypoglycemia did not show a significant difference between the two groups. however, the authors noticed that microdialysis glucose values showed a rising trend over the course of days of monitoring in the good outcome group. similarly, the good outcome group showed rising microdialysis glucose to blood glucose ratios. this indicates a recovering metabolic state in the brain tissue that may indicate a good outcome , (►fig. ). fig. collection of dialysate bedside for neurobiochemistry of microdialysis sample. fig. noncontrast ct showing focal hemorrhagic left frontal contusion (panel a). after removal of contusion, placement of microdialysis catheters in penumbra zone and normal contralateral (panel b). fig. microdialysis catheter being inserted after decompressive craniectomy. indian journal of neurosurgery vol. no. / cerebral microdialysis gupta, mazzeo difference between the two groups, comparing episodes of cerebral hypoglycemia during systemic hypoglycemic episodes (rbs < mmol/l), was significant (p ¼ . ). this probably reflects increased susceptibility of brain tissue to hypoglycemia, related to impaired autoregulation, in the poorer outcome group. the previous assumption that cerebral extracellular glucose concentration would change in parallel with blood glucose values may be an oversimplification. an increased metabolism of intracerebral glucose may lead to lower microdialysis glucose values following head injury. similarly, poor correlation has been also reported between blood and extracellular brain glucose in patient with sah. abate and colleagues attributed poor control of microdialysis glucose based on blood glucose values secondary to the metabolic heterogeneity that may be expected in tbi patients. nagel et al noted weak correlation between cerebral and serum glucose; however, the trend of values for cerebral hypoglycemia, lpr, and cpp correlated well with outcomes in their series. lactate/pyruvate ratio after dc, gupta et al showed that mean lpr was significantly higher in the poor outcome group than the good outcome group (mean . [sd . ] vs. . [sd . ]; p < . ). cpp had an inverse correlation to the lpr for the whole cohort as would be expected with increased perfusion (p ¼ . ). an inverse correlation was also seen in the unfavorable outcome group (p < . ). , nikaina et al previously showed that cpp and lpr have significant effects on the long-term outcome prognosis after a spontaneous cerebral hematoma. they proposed a cutoff cpp of � mm hg and lpr � . parafarou et al suggested a cpp cutoff > mm hg, lpr < , and glycerol < µmoles/l as markers of good outcome. this study shows somewhat similar results (lpr < and cpp � mm hg). in the event of tbi, ischemia and decreased cerebral blood flow can occur even with cpp � to mm hg. , therefore, cpp alone is not a reliable indicator to assess adequacy of the cerebral blood flow in such patients. there is, however, no consensus for the ideal cpp values in severe tbi. some authors have warned about a higher risk of acute respiratory distress syndrome with a cpp > mm hg, with no additional benefit to outcome. a lower cpp goal of mm hg has been endorsed by the american association of neurological surgeons, and recently the brain trauma foundation suggested a general threshold in the area of to mm hg. an elevated lpr can have various causes such as ischemia, hyperglycolysis, and mitochondrial dysfunction. – the key to finding the appropriate cutoff for cpp may depend on keeping a favorable metabolic profile, as indicated by low lprs. glutamate increased levels of extracellular glutamate have been reported in human tbi, with persistent glutamate elevation seen in the postinjury period. in ischemic models, levels have been seen to rise from to > µmol/l. in the studies by gupta et al, levels of glutamate were significantly higher in the bad outcome group than the good outcome group: . µmol/l (sd . ) versus . µmol/l (sd . ), p < . . – recovering trends of glutamate values were seen in the good outcome group over a period of days, consistent with previous studies. this confirms that glutamate could be a useful prognostic marker in tbi. mitochondrial dysfunction and ischemia as mentioned earlier, the lpr elevation has been seen to occur in conditions of ischemia (with a fall in pyruvate) and also in mitochondrial dysfunction (with a near normal pyruvate level). gupta et al noted that the unfavorable outcome group showed significantly higher episodes of both mitochondrial dysfunction and ischemia than the favorable gos group: . % versus . % (p < . ); . % versus . % (p < . ), respectively. , these changes were more pronounced with pericontusional catheter placement. the authors compared the results for the time spent in each category, post-resuscitation gcs and age to the gos score at last follow-up. for most patients being monitored for a period of to days, this meant that even a % increase in ischemia ( – hours), as shown by microdialysis, doubled their odds of progressing to a worse outcome group. similarly, for mitochondrial dysfunction, the odds ratio was . ( % confidence interval [ci]: . – . ) (p ¼ . ). during episodes of ischemia, the icp was significantly higher and the cpp significantly lower. in view of the odds of worsening outcome with each episode of ischemia, close control of cpp should be maintained. ischemia and mitochondrial dysfunction require different therapies. if a condition is characterized as fig. over days of intracerebral microdialysis (md) monitoring, the good glasgow outcome scale (gos) showed a rising cerebral md glucose and cerebral/blood glucose ratios. md glucose is expressed in mmol/l and random blood glucose (rbg) in mmol/l. rbs, random blood sugar. indian journal of neurosurgery vol. no. / cerebral microdialysis gupta, mazzeo ischemic based on microdialysis values of the lpr and pyruvate levels, therapy is indicated to increase cpp or to pharmacologically improve microcirculation. on the other hand, bedside detection of nonischemic mitochondrial dysfunction should lead to consideration of novel therapies targeting mitochondrial function, such as hyperbaric oxygen (►fig. ). it is important to notice that in tbi shifting of energy metabolism from aerobic to anaerobic glycolysis may occur not only because of lack of oxygen delivery but also because of failure of effective utilization of the delivered oxygen due to mitochondrial dysfunction. this leads to a nonischemic lpr elevation, which has been designated type elevation. this is what vespa and colleagues have demonstrated in fig. low pyruvate levels in ischemia and high pyruvate levels in mitochondrial dysfunction patients as detected by cerebral microdialysis. lactate/ pyruvate (lp) ratio is raised in both groups. gluc, cerebral glucose, la, cerebral lactate levels; lpr, lactate/pyruvate ratio pbto , brain tissue oxygenation; pyr, cerebral pyruvate levels. table summary of the consensus statements and recommendations regarding cerebral microdialysis consensus statement recommendation evidence methodology of microdialysis -kda catheters for small molecules and -kda for large molecules flow rate of . µl/min with hourly sampling recommended reference values glucose (tier intervention) < . mmol/l < . mmol/l low glucose associated with poor outcome l/p ratio (tier intervention) > > high l/p ratio associated with poor outcome lactate > mmol/l l/p ratio better than lactate glutamate (tier ) raised in ischemia may be useful in prognostication glycerol (tier ) limited specificity no definitive evidence management guidelines glucose raise rbs if low treat perfusion, if low cpp l/p ratio if ischemia, raise cpp if low pbto , improve oxygenation catheter placement focal injury a) ipsilateral b) in normal brain multiple catheters may be used diffuse injury right frontal lobe monitoring trend is more important than absolute point values abbreviations: cpp, cerebral perfusion pressure; l/p ratio, lactate/pyruvate ratio; pbto , brain tissue oxygenation; rbs, random blood sugar. indian journal of neurosurgery vol. no. / cerebral microdialysis gupta, mazzeo their combined md and positron emission tomography (pet) study, in which md data revealed a % incidence of lpr > but only a . % incidence rate of ischemia, as indicated by lpr > and glucose < µmol/l or pet- oxygen extraction fraction > . . in addition, lpr elevations correlated with reduced cerebral metabolic rate for oxygen, which is a measure of mitochondrial oxidative metabolism, suggesting that lpr is an indicator of mitochondrial dysfunction. this observation suggests the importance of using other markers of cell damage (glycerol and/or glutamate) in addition to lpr for a correct interpretation of this variable. consensus guidelines on use of cerebral microdialysis a recently held consensus meeting by the international microdialysis forum, led by p. j. hutchinson, combined literature review with expert opinion to produce practical guidance for the use of cerebral microdialysis (►table ). conclusion among the several neuromonitoring tools available nowadays, cerebral microdialysis seems to accomplish most of the queries that researchers and clinicians ask to these devices in the care of patients with acute brain injury: to detect secondary insults in real time, at the time in which they can still be corrected; to clarify pathomechanisms of injury; to understand alterations in cerebral energy metabolism; to evaluate the effect of medical or surgical interventions on brain metabolism; to evaluate the effect of invasive rescue therapies such as dc in patients with intractable intracranial hypertension; to provide markers of effectiveness of therapeutic intervention; and to help in designing of clinical studies. therefore, monitoring neurochemistry by microdialysis can possibly provide clinicians with additional information in several related aspects of management. robust neurochemical changes have been detected in response to clinical pathophysiologic events after an acute brain injury, so that the specific effect of dc on the different pathomechanisms of injury can be difficult to isolate from primary injury and other therapies using these neuromonitoring tools. although cerebral microdialysis and other types of multimodality monitoring have been in use for almost two decades, their potential is huge for the future. limits of this monitoring tool are represented especially by its high cost, its local aspect, and by the need to experienced personnel, so that its use is not widely diffused across the globe. therefore, even if no doubt exists on its usefulness as research tool, as demonstrated by two decades of literature in human tbi, the real impact of this monitoring in dictating specific changes in management during daily clinical practice remains to be demonstrated in larger studies. conflict of interest none. acknowledgments the authors wish to thank dr. raghav singla (resident neurosurgery) and staff nurse jyoti sohal (jpnatc) for their assistance during neurobiochemistry monitoring by cerebral microdialysis in tbi patients. references reinstrup p, ståhl n, mellergård p, uski t, ungerstedt u, nordström ch. intracerebral microdialysis in clinical practice: baseline values for chemical markers during wakefulness, anesthesia, and neurosurgery. neurosurgery ; 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( ) acta physica polonica a no. special issue of the nd international conference on computational and experimental science and engineering (iccesen ) importance of corporate governance for energy in sustainable development and evaluation with quantitative swot analysis b. tugrula,∗ and s. cimenb aistanbul technical university, nuclear researches division, istanbul, turkey bministry of energy and natural resources, ankara, turkey human development goals should be meeting with sustaining the ability of natural systems to continue to provide the natural resources and ecosystem services upon which the economy and society that is “sustainable development”. for this aim, corporate governance and related activities are important that broadly refers to the mechanisms, processes and relations by which corporations are controlled and directed. swot analysis is a method that considers strengths and weaknesses along with the opportunities and threats that exist in the incorporated body environment. internal and external factors generate ideas about how their incorporated body might become more successful by using swot analysis. for logic comparison of these ideas, analytic hierarchy process was applied for swot analysis and important values of them were determined and evaluated rationally. doi: . /aphyspola. . pacs/topics: . .mn, . .–j . introduction energy growth is directly linked to welfare and pros- perity of the countries in all over the world. therefore, energy has a pivotal role in every society, touching upon all aspects of life and creating the welfare of people and consolidates the country’s standing among the others. usage and management of energy is an important mea- suring criterion for the countries in the view of evaluation for developing statute in the world, but in many case it is not appropriate to sustainable development. energy management is important and it has govern- mental and private factors in complexity. therefore, reaching out the energy resources or producing of it is an important target for all over the world. access to the energy and/or energy resources, in particular providing energy sources in large scale, has become an indispens- able requirement for the countries and it is affected on global warming [ – ]. environmental sustainability is the process of making sure current processes of interaction with the environ- ment. therefore, environmental sustainability demands that society designs activities to meet human needs while indefinitely preserving the life support systems of the planet. on the other hand, positive momentum creating for elevating climate change can be realized by the corpo- rate governance priority [ ]. especially, including power, oil and gas, coal, air transportation and food products should be driven by this concept. it requires that leaders of corporate governance deliver short-term financial re- turns for the challenges that climate change presents in the long term. ∗corresponding author; e-mail: beril@itu.edu.tr sustainability is important for the liveable earth. as known that: “sustainable development is development that meets the needs of the present without compromis- ing the ability of future generations to meet their own needs.” [ ]. sustainable energy is a concept for applica- tion of energy systems. sustainable energy is important for the welfare of the countries. therefore sustainable en- ergy related to economic growth, environment and social equity simultaneously is vital for our earth [ ]. figure represents energy sustainability in the total sustainability concept [ ]. fig. . energy sustainability in the total sustainability concept. . importance of governance and corporate governance global knowledge can be realized on the basis of differ- ent institutional and organizational arrangements such as public institutes, the private association of firms or private-public partnerships. the relationship between lo- cal industrial and global value chains can be structured into different institutional frameworks and regulated on the basis of different corporate governance models. be- ing linked to global value chains represents a learning opportunity that enterprises in developing countries can exploit to upgrade their capabilities. the possibility for realizing specific macro policy goals hinges on their capacity affected by corporate governance ( ) http://dx.doi.org/ . /aphyspola. . mailto:beril@itu.edu.tr b. tugrul, s. cimen in the information age. this procedure is very important for all countries in the name of sustainable development. it can be said that capacity and readiness influence coun- tries’ structural trajectories and underlying production and technological capabilities directly connecting with corporate governance [ ]. comparison of governance and corporate governance can be seen in fig. . fig. . comparison of governance and corporate governance. energy needs stimulate new developments. it should be applied by organizational and systematic activities, but it has feedback effects which can be harmful for the sustainability concepts. therefore, the corporate gover- nance is also important for energy applications and af- fected by global warming. . swot analysis swot analysis is a tool in order to appraise the strengths, weaknesses, opportunities and threats in a project or decision making with a strategic approach. it includes determining the goal of the project or de- cision making with diagnosing the internal and external factors which are supportive and unsupportive to suc- ceeding that goal [ ]. to achieve an effective swot analysis and get competitive benefits of each category (strengths, weaknesses, opportunities and threats) users have to ask and answer meaning questions [ ]. consid- ering the facts of corporate governance for energy swot analysis table can be seen in table i. table i swot analysis table of corporate governance for energy. strengths weaknesses supporting by community (s ) energy lack no permit to orga- nize the corporate governance (w ) international applicability (s ) political preferences (w ) support the sustainability (s ) hardness for adjustability (w ) opportunities threats increasing the conscious for sustainability (o ) regional energy crises and con- flicts (t ) international agreement re- lated with sustainability & global warming (o ) risks for energy supply secu- rity (t ) high comprehension(o ) rising trend of energy prices (t ) main key information can be taken from internal and external analysis. strengths or weaknesses of the corporate governance for energy depending upon their effect can be determined by own objectives that is inter- nal analysis. similarly, opportunities and threats eval- uation represents as external analysis for the corporate governance for energy via swot matrix in table i. use of conventional swot analysis bases on qualita- tive analysis and has no means of determining the im- portance of each swot factors. for this reason, an advance application was applied in the swot analy- sis that has been proposed weighting and rating indi- vidual swot factors using the pairwise comparison ma- trices [ ]. therefore, analytic hierarchy process (ahp) was applied for the quantitative swot analysis. table ii weight values of swot analysis factors. swot arguments s s s w w w o o o t t t weights . . . . . . . . . . . . analytic hierarchy process is a multi-criteria decision making technique which decomposes the problem into a system of hierarchies, whereas the statistical assess- ment — linear alignment technique sorts the compared arguments by their scores and yields the best result by choosing the argument with the highest score. ahp is a structured technique for organizing and analyzing com- plex decisions based on mathematics that was applied in the study. it provides a comprehensive and rational framework for structuring a decision problem, for repre- senting and quantifying its elements, for relating those elements to overall goals, and for evaluating alternative solutions. the ahp converts these evaluations to nu- merical values that can be processed and compared over the entire range of the problem. a numerical weight or priority is derived for each element of the hierarchy [ ]. the weight values of swot analysis factors in table i are given in table ii. the priority value is given to those characteristics and is applied of swot analytical method. ahp matrix was created with the ahp application. this matrix is normalized and ultimately reached a preference matrix. these numbers represent the alternatives’ relative ability to achieve the decision goal. . results and discussion firstly, evaluation of swot analysis is realized by in- ternal and external analysis for the corporate governance. as the internal analysis via swot matrix it is deter- mined that: • energy lack does not permit to organize the corporate governance in spite of supporting by community; • political preferences are important factors for in- ternational applicability; importance of corporate governance for energy. . . • hardness for adjustability should be solving via supporting sustainability for corporate governance. as the external analysis via swot matrix it is deter- mined that: • regional energy crisis and conflicts should be solved by increase of consciousness for sustainability; • risks for energy supply security drive international agreement for sustainability and climate change; • rising trend of energy prices should be evaluated with high comprehensive for corporate governance. for the “quantitative swot analysis”, “ahp matrix” was established according to weight values in table i and normalized and determined the “priority matrix” for each element of the hierarchy. priority values can be seen in table iii. table iii priority values of swot analysis factors. swot arguments s s s w w w o o o t t t priority values [%] . . . . . . . . . . . . after the quantitative swot analysis, it is understood that the factors on • international applicability, • increasing the consciousness for sustainability, • international agreement for sustainability, • high comprehension have the strategic importance for the corporate gover- nance for energy. . conclusion corporate governance and related activities are impor- tant that broadly refers to the mechanisms, processes and relations by which corporations are controlled and di- rected especially for energy and energy supply security. important factors for corporate governance energy man- agement with the incorporated body environment can be evaluated by swot analysis and also quantitative swot analysis via applying ahp. with the study, the main strategic objectives can be determined clearly by internal and external analysis with swot analysis. in the results of quantitative swot analysis, rising trend of energy prices with high com- prehension causes the risks for energy supply and also causes the regional energy crisis and conflicts, but they can be solved by increasing consciousness and drive inter- national agreement with the sustainability concept and related with global warming. references [ ] a.b. tugrul, j. en. power eng. , ( ). 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[ ] t.l. saaty, k. peniwati, groupdecision making: drawing out and reconciling differences, rws publ., pittsburgh, pennsylvania . http://dx.doi.org/ . / - - - - _ http://dx.doi.org/ . / - - - - _ http://dx.doi.org/ . / - - - - _ http://dx.doi.org/ . /s - ( ) - http://dx.doi.org/ . / http://dx.doi.org/ . / - - - - .ch http://dx.doi.org/ . / - - - - .ch strike out the plan of developing chinese pattern wind power generation available online at www.sciencedirect.com energy procedia ( ) – – © published by elsevier ltd. doi: . /j.egypro. . . iaceed strike out the plan of developing chinese pattern wind power generation wang hepinga, luo weib*, wun yunnaa, a,b north china electricity power university, no. , beinong road, huilongguan, changping district, beijing and , china abstract top ics on energy crises, environment p rotection have app eared in international confer ence time and again , usage of renewable ener gy is a p op ular subject , and wind p ower gen eration is the industry with relatively low cost and mature technology , which is dev elop ed by many governments as an imp ortant industry . the article first introduces current situation of china’s wind p ower generation briefly , and then describes its own features and p roblems differing from other countries in the world in detail. finally , we p ut forward a p rop osal to develop wind p ower gen eration in chinese p attern way , and meanwhile we give some advices and methods. keywords: wind power generat ion; china pattern; renewable energy; advice; specific condit ions . introduction with the rapid develop ment of world economy , industrialization level is higher and higher, meanwh ile global environment degradation and non -renewab le energy c risis have beco me worldwide prob le ms. in recent years, the subject on developing new energy has drawn attention of many govern ments. in , our country promised to the international society that the ratio of non-fossil fue ls to prima ry energy consumption would reach % in , and per unit of gdp carbon e missions of would decrease by %~ % compared to that of . china still takes coal as ma in consumer of energy because of historica l and environmental factors, and this consume structure could speak for itself about how large pressure it makes on environ ment. it’s to optimize energy structure, improve energy effic iency, and to develop renewab le energy that becomes * corresponding aut hor. tel.: + - - - - . e-m ail address: st efanie.d @yahoo.com.cn open access under cc by-nc-nd license. © published by elsevier ltd. selection and peer-review under responsibility of riuds open access under cc by-nc-nd license. http://creativecommons.org/licenses/by-nc-nd/ . / http://creativecommons.org/licenses/by-nc-nd/ . / wang heping et al. / energy procedia ( ) – important and indispensable components of sustainable development strategy. as bulk of energy consumption, electric ity industry plays an important role in new energy development . w ind power fie ld has a relatively mature technology and low cost and has the highest researching and developing value. . current situation of wind power in china china has rich wind resource. according to a detailed survey, . billion kwh wind power fac ility can be installed on land in china, and the total nu mber of resources can reach b illion kw h in cons ideration of the maritime part. wind power develop ment is like a blue streak in china [ ]. the early s of last century was the promotion stage when the wind turbines and installed capacity continuously increase d. recently, the development is surprisingly quick with installed capacity growing by the rate of more than % . in , we installed mw in total and surpassed denma rk to be the fifth largest one in the world, and the number of is mw which surpass ed india, and the number reached . mw before the end of . as the promise we have made to the global society mentioned above, our government positively encourages and supports the development of wind powe r industry, with the ride wind progra m the state planning co mmission brought forward a symbolic marker, besides, the government has made a lot of preferential policy, for e xa mp le, the wind powe r ta x has shifted fro m a production value added ta x(vat) to a consumption vat, import tariff and value-added ta x on co mponents and materia ls and others related to high-power wind power generation machine would carry out a refund after collection. furthermore, there are many enterprises and individuals in society which have seen the profitable and policy supportive future of wind powe r development, and driven by potential great benefits ; they want to take a share of the substantial profits . then, they step into the field fro m time to time and invest various kinds of technologies and capital; the great number of private investments speed up the development of wind turbine and in the other way round, the correlative equip ments and materials manufactories would activate the localization process of wind turbine. . the characteristic and existed problem of wind power in china in view of our particu lar geographical conditions and fundamental rea lities, we have our own special characteristics different fro m international society in developing wind power, and there ’re some proble ms appealing with installed capacity growing rapidly. ( ) non-equilibriu m of national economy and wind resource. even china is rich in wind resource, the distribution is unbalanced. wind resources are concentrated mainly in the three northern regions and the eastern coastal areas , while only some inland areas have wind resources because of their special terra in or lakes . the distribution of total installed capacity of each province in china is shown in figure , fro m which we can recognize the different richness of wind resources. wang heping et al. / energy procedia ( ) – figure t ot al inst alled capacity of each province in china in besides, ch ina seeks for priority develop ment of some a reas; economic development is imba lance and so is affordability of electricity price. so me territories rich in wind resource are in the places with weak grid, especially the three northern regions. as natural resource, wind energy has inherent properties. the wind is a lways intermittent and has great randomness, leading to randomness and instability of wind power generation wh ich shall increase difficulty in balancing the load [ ]. thus, a high stability of grid network is necessary. grid network not stable enough would cause serious stability and security threat. ( ) a particu lar e lectricity ma rket background. co mpared to economy relat ively developed europe and the usa, our e lectricity cons truction started later. even we have entered the world's leading ranks after years ’ electric ity reform in many ways ; we are not perfect in power technology, regulation system, or ma rket mechanis m. ch ina is still in wind power systems’ e xplorat ion and trial stage. as an energy industry, electricity power industry is closely related to industrial development, technological progress and other social aspects of living and large-scale state-owned enterprises are always being the leader of monopoly [ ]. on national level, there is much to be desired in competition of market mechanism. the overall e lectricity mechanism is not perfect, so the develop ment of china ’s wind powe r is accompanied simu ltaneously with e lectricity reform, which increase the difficulty o f wind power development and the relevant departments are not able to make co mprehensive and global development program, and as a result, we can not ma ke overall plan in conjunction with other fie lds ’ evolution and technical updates fro m the perspective of long-term develop ment of wind power. with the rap id development of wind power, establishing a reasonable wind power market mechanis m is necessary. moreover, as a part of e lectric ity construction, grid building -up needs a further pro motion and perfect ion. in general, ch ina’s current coverage of grid construction is not broad enough, and we have to get confronted with existed problems wh ich have become constraints, like the lac k of adequate stability and security and the difficulty in dealing with unexpected accidents. ( ) a diffe rent prima ry target and e xpansion path in developing wind power. as we a ll know, eu is earliest to develop wind power and has the h ighest utilization. throughout the history of the european union’s wind powe r develop ment, its technological progress is taking the first road before the scale e xpansion. after continuous technical innovation and improvement, its wind power technology has been a world leader, although mangy countries (including the un ited states, china) have rapid developmen t of wind power industries, eu re ma ins the world’s ma jor equip ments suppliers. in , the european enterprises ’ share of relevant products accounts for % [ ]. it is the high costs of wind power that ma inly restrict its further develop ment and spread. recently, world wind energy council research questions about how to ma ke a further improve ment in cutting wang heping et al. / energy procedia ( ) – down the cost showing that scale e xpansion contributes to decline of wind powe r cost by % , and the re main % part re ly on technical progress. since eu had developed its technology, the next effort would be scale e xpansion, standardization and serialization to reduce costs. recently, eu continually ra ises its installed capacity, and updates its capacity plan and target again and again to lo wer costs through scale e xpansion on a large scale because of usual achievement of capacity goal in advance. it can be expected that wind power would be an important alternative energy source in eu before long. as for a merica, it a lso tries to replace the oil fossil resources with wind resources on the pre mise that domestic electric ity supply is enough for the demand or even e xceeding the de mand. it has two objectives to develop wind power; one is to solve the pollution proble m and improve the environ ment quality and the other is to deal with the energy crisis and develop renewable resources. china diffe rs largely fro m them. in peak season, our electric ity supply is still insuffic ient to meet the demand of users and we o ften cope with electricity c risis with spasmodic powe r supply by load shedding . so, we develop wind power aiming at solving the electricity supply insufficiency at first and then the sustainable development and environmental protection [ ]. thus, china makes its developing path with scale expansion going in paralle l with technology development, or even with the scale expanding earlier than technological progress. therefore, in current, wind power industry evolution is like a raging fire and we have achieved a great- leap-forward development, with the supportive policy. for e xa mple , installed capacity racks up wh ile the program updates again and again. however, such an overheating evolution leads to unplanned and disorderly development at the same . there are many prob le ms like the investment in wind powe r rus hing headlong into action and repeated importation, which cost a lot of financia l and human resources. besides, technological progress can not catch up with wind power e xpansion. good and bad quality of production of domestic wind turbines and related equipments manufactories mixed together. all these factors mentioned are causing huge potential dangers to the future wind power. before , mo re than % of our wind power equip ments were imported or manufactured with foreign proprietary technology. in order to decrease the cost of wind power and develop domestic wind power equipments manufactories, taking view of technologies development, the government requires a growth in the localization rate of parts and components in wind turbine. in , national develop ment and reform co mmission introduced the provisions named the notice about requests related to wind power construction and management stipulating that localization rate of parts and components of wind power equip ments should reach % and those wind farms that can not meet the de mands are not allo wed to build. with the policy, as of , ho me made wind turbines have taken over % the market and so the government cancels the rule at the beginning of this year. with such a rapid development, we cannot help asking how much development is made by real technological and what about the remaining part? even today, ch ina has not establish ed quality standard system of wind power equip ments, under which condition those machines enter the market if only they pass an unprofessional quality exa mination wh ich is usually unilateral. as a result, we can imagine what a big potential risk we are taking. . advices -wind power of chinese pattern here are several advices about making chinese pattern way to develop wind power. in general, the wind power of china has a rosy prospect and coexists with some problems. ( ) continue the policy support. fro m the evolution history of world wind power, no progress would be made in any country or territory without the supporting policy of the government. in addition to e xisted incentives, the famous carbon tax we p lan to promu lgate will stimulate the wind power development to a large degree. wang heping et al. / energy procedia ( ) – ( ) establish regulation systems. though government canceled the require ment that localization rate of components should reach % is sure to bring about foreign manufacturers grabbing chinese market, we must strive to develop homemade wind turbine s and make great efforts to realize a b ig boost of localization rate in wind powe r industry chain with rea l ly mature technology. during the stage, wind power equip ments manufacturing industry rules must be established and market mechanis m should be built. moreover, we need to regulate unplanned development and actively prevent the quality and cost problems caus ed by repeated introduction of foreign equipments or technology. ( ) never regard installed capacity as target simply. currently, the proble m that electric ity can be generated but not be transmitted is very grim. after build ing many wind farms with high e xpense, isn’t it worth the candle if the electric ity is useless ? developing wind power is to meet de mands rather than to build up lofty wind power image. w ith so fast an evolution, a professional progra mming depart ment is needed to ma ke overa ll plans and pro mote utilizat ion of wind power instead of seeking the capacity number blindly; meanwhile we need to perfect grid quality and improve stability and reliability. ( ) achieve the plura lism of utilization patterns. at present, some do mestic scholars put forw ard the wind powe r non-grid-connection theory, and the non -grid wind power being used directly in high powe r- consuming industries is proved available with broad prospects [ ]. as to the utilizat ion patterns, we could choose the most economic and feasible method according to circumstances. ( ) set up wind power information center collecting data about wind turbines . even if we want to ma ke search, the related data is insuffic ient. so it is necessary and urgent to build an information center. besides, whether the wind farms run we ll or not, they can make profits because of supportive policy, so an information center is required for the society to get acquainted with the operation status . . conclusion chinese special economica l, environ mental and technological characteristics lead to its particular wind power background, which is different fro m international world. to develop the wind power in long time, china needs to strike out its own developing plan, which is the chinese pattern wind power road. references [ ] liu chunge, chen ge. current sit uat ion and view about development of the wind power in our country[j]. agricultural engineering technology (new energy industry), ( ): - (in chinese) [ ] huang yi, zhang yibing, sun qiang et al. some suggest ions on the measures for high-speed wind power development in china [j]. energy technology and economics, , ( ): - (in chinese) [ ] shen xiaoyang, yang junbao, jiang xiaohua. p reliminary st udy on t he present condit ions and reform t rends of elect ric power const ruction market [j]. journal of shanghai university of electric power, , ( ): - (in chinese) [ ] bureau of energy, nat ional development and reform commission [j]. china econom ic&trade herald, ( ): - (in chinese) [ ] gu weidong, the influence of t he wind power non -grid-connect ion theory to wind power indust ry in china and it s prospect analysis [j]. shanghai electric power, ( ): - (in chinese). managing editor: roberto raga email: roberto.raga@unipd.it detritus / volume - / pages iii-iv https://doi.org/ . / - / . © cisa publisher books review waste biorefinery: potentials and per- spectives by thallada bhaskar, ashok pandey, s.venkata mo- han, duu-jong, and leesamir kumar khanal the major drivers of bioenergy of this century include the improvement of energy security, addressing the issue of finite amounts of fossil fuels and natural resources and mitigation of the effects of climate change. consequently, due to the currently ongoing energy cri- sis, focus on the production of biofuels and bio-products has increased worldwide. biofuels and bio-products can be produced from biomass by means of a conversion process known as biorefinery. however, the key questions we should attempt to pro- vide an answer to are: ‘are biofuels and bio-products fully sustainable?’ and ‘how might we solve the biofuel/bio-prod- uct vs food and tank or table debates?’. indeed, at times pre- cious plant-based resources, obtained using fertile land and water, are shifted from the production of food and feed to the generation of bio-energy or bio-materials, thus resulting in the development of a sensitive social issue. this may only be solved by eliciting a change in mentality: indeed, wastes (b) should no longer be regarded as residues to be treated and disposed of, but rather as a valuable resource that can be exploited as renewable feedstock for use in the production of bio-energy and chemicals. this is precisely the strategy adopted by the so-called “waste biorefinery” approach which is investigated in detail in the book “waste biorefinery: po- tentials and perspectives”. the latter incisively shows how true sustainability can be achieved by valorising what has until now been considered a useless residue, whilst at the same time helping to identify cost-effective strategies. the book is divided into chapters grouped into broad sections. section a relates to an analysis of the waste feedstocks suitable for use in biorefinery and the most re- cent technologies that contribute towards enhancing the sustainability and efficiency of the conversion process. in particular, it is highlighted how the waste biorefinery fits perfectly within the circular economy regenerative system. section b provides a detailed insight into the advanced and innovative methods for biomass conversion, namely thermochemical and combined gasification-fermentation. likewise, sections c, d, and e focus on the wide range of possibilities related to the valorisation of food waste, mu- nicipal solid waste, and lignocellulosic waste, respectively. food waste is preferentially used as a substrate in anaerobic digestion and acidogenic fermentation processes in order to gain biogas and biological monomers, respectively. pyroly- sis is the method investigated for use in the conversion of municipal solid waste into bio-energy products. lignocellu- losic resources are efficiently valorised in a number of ways, including hydrothermal treatment, pyrolysis, microwaves, and ultrasounds. since lignin cell walls are particularly diffi- cult to break down, specific pre-treatments, such as the use of ionic liquids, are also illustrated in the book. furthermore, section f explores the innovative field of water-based biore- finery relating to both the recovery of resources through bioelectrochemical systems and the potential of exploiting microalgae biomass. in the first part, nutrients, metals, en- ergy, and chemical products are investigated and a series of case studies commented on. in the second part, in ad- dition to considering microalgae cultivation for use in the production of bio-fuels, closing the loop of the microalgae biomass is the main goal, demonstrating an expanding mar- ket for food and feed additive production, and for high-value chemicals. section g deals with biorefinery projects on the cutting edge of scientific research. at the beginning of the section, three types of biomass residues generated in arid/ semiarid regions (palm tree residues, seawater biomass residues, and organic fraction of municipal solid waste) are reviewed. subsequently, castor biorefinery is carefully ex- plained with a special focus on castor oil and the different ivbooks review / detritus / volume - / pages iii-iv extraction methods applied. insect-based bioconversion is another hot topic addressed in this section. indeed, insects are capable of stabilizing organic waste while enabling the recovery of bio-fuels, fertilisers, food, and polymers. the last chapter describes how advanced thermochemical tech- nologies, with particular focus on pyrolysis, are capable of converting low-value materials such as deinking residues from the paper industry into value-added products. finally, section h provides a discussion on integrated technologies and approaches associated with lignocellulosic biomass, in- cluding pre-treatments required, and describes a case study of a woody biomass biorefinery in japan. to conclude, through a balanced combination of differ- ent branches of science: chemistry, biology, engineering, and biotechnology, this book provides data-based information on the state of the art of biogenic waste utilisation within the field of biorefinery in which waste and resources are in- terchangeable. francesca girotto university of padova, italy email: francesca.girotto. @hotmail.it about the editors thallada bhaskar dr thallada bhaskar, senior scientist, is currently heading the thermo-catalytic processes area, bio-fuels division (bfd) at csir-indian institute of petroleum, india. his years of research experience cover various fields of science revolving around his expertise in heterogeneous catalysis thermo-chemi- cal conversion of biomass, waste plastics and e-waste plastics into value added hydrocarbons. he has carried out several re- search projects with great success with national and interna- tional collaborators. ashok pandey professor ashok pandey is currently distinguished scientist at csir-indian institute for toxicology research, lucknow, india and honorary executive director at the centre for energy and environmental sustainability- india; he was the former deputy director for csir’s national institute for interdisciplinary sci- ence and technology at trivandrum, where he head the centre for biofuels and biotechnology division. professor pandey’s re- search interests are on bio-based economy for the production of fuels and chemicals. he has over publications and com- munications, which include patents and design copyright, books, book chapters, and original and review papers. s.venkata mohan dr.s.venkata mohan is working as principal scientist in csir-indian institute of chemical technology, hyderabad since . he was a visiting professor at kyoto university ( ) and alexander von humboldt (avh) fellow at technical univer- sity of munich, germany ( - ). his main research interests are in the domain of environmental bioengineering specifically in the areas of advance waste remediation, aciodogenesis, mi- crobial electrogenesis, photosynthesis and waste biorefinery. he has authored more than research articles, chapters for books, edited books and has patents. his publication has more than , citations with an h-index of (google scholar). he has guided phds., m.phils and more than m.tech./b.tech./m.sc. students. recently, dr mohan recently successfully demonstrated a pilot plant for biohydrogen pro- duction from waste for mnre and waste fed biorefinery plat- form for csir. duu-jong lee duu-jong lee is currently a life-time specially appointed professor of national taiwan university (ntu) and chair pro- fessor and dean of college of engineering of national taiwan university of science and technology (ntust). during the past years of his career, he has completed several projects successfully and developed various processes with full-scale applications. the research carried out till-date has credited him with more than publications/communi- cations. the citations in scopus on dr lee’s work has exceed- ed with h= . professor lee is the recipient of many na- tional and international awards and fellowships. samir kumar khanal dr. samir kumar khanal is an associate professor of bio- logical engineering at the university of hawai‘i at mānoa. previ- ously, he was a post-doctoral research associate and research assistant professor at iowa state university for years. dr. khanal is also an editorial board member of the highly prestigious international journal, bioresource technology and korean journal of environmental engineering. he is also a recipient of ctahr dean’s award for excellence in research ( ), university of hawaii at manoa. dr. khanal is a professional engineer (environmental engineering) in the state of iowa. book info: editors: thallada bhaskar / ashok pandey / s.venkata mohan / duu-jong lee / samir kumar khanal imprint: elsevier published date: th january page count: ebook isbn: paperback isbn: thearwh.org -&nbspthis website is for sale! -&nbspthearwh resources and information. thearwh.org buy this domain the owner of thearwh.org is offering it for sale for an asking price of  usd! this webpage was generated by the domain owner using sedo domain parking. disclaimer: sedo maintains no relationship with third party advertisers. reference to any specific service or trade mark is not controlled by sedo nor does it constitute or imply its association, endorsement or recommendation. privacy policy an energetic programme econstor make your publications visible. a service of zbw leibniz-informationszentrum wirtschaft leibniz information centre for economics mayer, otto g. article — digitized version an energetic programme intereconomics suggested citation: mayer, otto g. ( ) : an energetic programme, intereconomics, issn - , verlag weltarchiv, hamburg, vol. , iss. , pp. - , http://dx.doi.org/ . /bf this version is available at: http://hdl.handle.net/ / standard-nutzungsbedingungen: die dokumente auf econstor dürfen zu eigenen wissenschaftlichen zwecken und zum privatgebrauch gespeichert und kopiert werden. sie dürfen die dokumente nicht für öffentliche oder kommerzielle zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. sofern die verfasser die dokumente unter open-content-lizenzen (insbesondere cc-lizenzen) zur verfügung gestellt haben sollten, gelten abweichend von diesen nutzungsbedingungen die in der dort genannten lizenz gewährten nutzungsrechte. terms of use: documents in econstor may be saved and copied for your personal and scholarly purposes. you are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public. if the documents have been made available under an open content licence (especially creative commons licences), you may exercise further usage rights as specified in the indicated licence. www.econstor.eu e d i t o r i a l an energetic programme n owhere is the impact of the decline of the u.s. power - and the crisis of american leadership - more evident than in the crucial area of energy - so business week last march. recently president carter attempted to refute this judgement by taking several dramaturgically attuned initiatives - a phase of contemplation and discussion in historic camp david, a memorable speech to the americans and a shake-up among the leading people of his administration. the crucial point of his address was the appeal to his fellow- countrymen to acknowledge the securing of energy supplies as a historic task and to recollect the traditional virtues that made the united states what it is now. doubtlessly the energy problem represents an epochal challenge to the usa as well as to other countries. in the case of the usa perhaps not only because it is the world's major consumer of energy but even more so because the solution of the energy problem is affecting some of the traditional and deeply rooted values of the american society. greatest possible freedom and scope for the individual as well as the ideal of a highly mobile society are certainly to be valued differently in times of relative abundance than in a situation of relative shortage. it remains to be seen whether or not the european scale of values will prove to be more lasting in view of the energy crisis as recently a californian professor supposed. certainly, however, it can, somewhat simplified, be established that the european countries in their history never disposed of such an abundance of energy at such low prices as the united states did during the more than years since their foundation. in a retrospective view this applies to the affluence in timber and coal as well as to oil - after all, the industrial oil- age started in the sixties of the th century in western pennsylvania and not in riyad. this affluence of energy in the past has shaped the american way of life in almost all its aspects. for this reason it is so difficult for the individual american to perform the necessary turnabout toward a policy founding on a comparative shortage. it is this difficulty that characterises carter's by now fifth start to make his fellow- countrymen understand the seriousness of the energy crisis. if he actually succeeded - what his appeals and saving programmes of the past years did not achieve - his address would have served its purpose - independent of possible shortcomings of the enery concept linked with this speech. with this concept difficulties will be found when it comes to details, but not only then. carter's promise that the usa will never again import more oil than in is no particularly convincing answer to the present problems; after all, in the usa achieved the highest imports in its history with a daily average of . mn barrels. since then imports have been slightly declining. and his suggestion in his cansas city speech to aim at daily imports of only . mn barrels already for this year almost borders on deception. true, this would be , barrels less than carter had promised this summer at the tokio-summit as the highest limit. however since the beginning of this year no more than . mn barrels per day have been imported on average in consequence of the slack business trend, i.e. the intereconomics, july/august already existing development is aimed at, not a single barrel less. if the recession has indeed already started in the usa - as most recent data let us suspect - demand should hardly grow during the next five months, so that this year's oil imports might remain even below the mentioned aim without any specific counter measure. but in view of the existing demand pattern and the production-technical relations this need not mean that the problem of queuing-up at america's gas-stations will be solved soon and permanently. these queues can certainly not be dissolved by means of the stand-by rationing authority as demanded by the president although this is likely to be approved by the congress. rationing can be regarded as a synonym for queues. the only effective means against them and for developing the necessary saving mentality of every individual citizen would be the decontrol of the gasoline price. this however is obviously politically inopportune, in spite of the declaration of war on the energy crisis. but what will happen if the queues at the gas-stations threaten to grow too long and the fuel oil supply in new england becomes a little more strained with the approaching winter? will - instead of reducing imports as a results of an economic downturn - the oil companies be allowed to import additional distillates as long as the total does not exceed the level of ? if so, who saves then in the strict sense of the word? in order to reduce the usa's dependence on foreign oil, according to carter during the next decade - financed by a tax on windfall profits and by loans - the enormous total sum of $ bn is to be invested, of which $ bn are to be used to produce . mn barrels a day of substitutes for imported oil by from coal, oil shale, the sun, plant products to produce gasohol and unconventional gas. by conservation an additional . mn barrels per day shall reduce the import requirements by the end of the next decade. however these magnitudes have to be seen against the background of a recent projection by the energy department that, even on reasonably optimistic forecasts of supplies of domestic oil, natural gas, coal and nuclear energy (not mentioned by carter in his first speech), oil imports are likely to rise from . mn barrels a day in to around mn barrels by the late s. although the gap between the import limit of . barrels and the forecast demand for mn barrels a day is narrower than the planned saving of foreign oil, the question must be asked if this planning it not a little too optimistic. for instance, it takes about ten years until a new coal mine reaches its full output and the energy department's projection supposes already a considerable increase of the contribution of coal to the energy supply - from the equivalent of to mn barrels a day. even if the planned energy mobilisation board can remove some environmental obstructions (although it cannot modify the environment protection laws) it is difficult to apprehend that the energy department's figures on the domestic energy supply until can be revised upwards to a decisive extent. the currently running pilot projects notwithstanding, an economically efficient technology is still missing for the planned exploitation of oilshale deposits and it will probably take more than ten years until solar energy can be utilised on a large scale. no wonder therefore that many observers missed a somewhat more unambiguous statement on the role of nuclear energy. even if this view should be too pessimistic and the mentioned targets should be more or less reached by the end of the next decade, it is striking that the proclaimed actions (in spite of their altogether right tendency) are too much directed towards a medium-term opening- up of alternative energy resources through an enormous effort. neglected is the somewhat safer, but also more hurting path of a quick saving of energy by the decontrol of the energy prices which for a long time have artificially been kept at a low level. both measures together would represet~ta wele-balanced programme. but the technological effort as well as the aversion to appreciable constraints for the abstention from the waste of energy are in line with traditional american values. unfortunately this is more than can be said of the idea of the necessary turnabout in an affluent society. otto g. mayer intereconomics, july/august energy crisis and new international equilibrium econstor make your publications visible. a service of zbw leibniz-informationszentrum wirtschaft leibniz information centre for economics schachter, gustav article — digitized version energy crisis and new international equilibrium intereconomics suggested citation: schachter, gustav ( ) : energy crisis and new international equilibrium, intereconomics, issn - , verlag weltarchiv, hamburg, vol. , iss. , pp. - , http://dx.doi.org/ . /bf this version is available at: http://hdl.handle.net/ / standard-nutzungsbedingungen: die dokumente auf econstor dürfen zu eigenen wissenschaftlichen zwecken und zum privatgebrauch gespeichert und kopiert werden. sie dürfen die dokumente nicht für öffentliche oder kommerzielle zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. sofern die verfasser die dokumente unter open-content-lizenzen (insbesondere cc-lizenzen) zur verfügung gestellt haben sollten, gelten abweichend von diesen nutzungsbedingungen die in der dort genannten lizenz gewährten nutzungsrechte. terms of use: documents in econstor may be saved and copied for your personal and scholarly purposes. you are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public. if the documents have been made available under an open content licence (especially creative commons licences), you may exercise further usage rights as specified in the indicated licence. www.econstor.eu articles oil problems energy crisis and new international equilibrium by gustav schachter* the author discusses the short-term and long-term aspects of the present energy crisis. he describes the various scenarios for the immediate future and the long run that could be given place by the emerging hold of opec over the oil consuming countries. t he energy crisis has subsided. oil is in abun- dant supply, but at four-fold prices. a short- run disequilibrium was created between produc- ers of primary goods and producers of inter- mediate and final goods. in the long-run, how- ever, the expectations are that a new international equilibrium will be established, which will con- tinue to be favourable to the nations producing the industrial goods, because these nations con- trol the productive aparatus of the world. for the short-run the energy crisis really has been a petroleum crisis, created by disequilibrium be- tween demand and supply. world demand of energy over the last decade increased faster than the capacity to produce energy. while the united states consumes one-third of the world's energy, the growth rate of energy demand has been much smaller in the united states ( . p.c.) in compari- son with japan ( p.c.) and the ec ( . p.c.). this growth rate has meant doubling the ec's energy demand every five or six years, and japan's every four years. there is a great difference also in the final use of petroleum. while in the united states about half of it is used for moving cars, in the ec and japan between - p.c. of all petroleum is used for industry and households. this adds dif- ferent dimensions to the problems faced by the united states vs. the ec-japan group. the united states cannot check the consumption of petro- leum with it's combination of large gas guzzling cars and no public transportation (an electric train carries a thousand people consuming energy equivalent of fifty cars). europe has less of a problem of petroleum consumption by cars since it has a wide spread and well developed railroad system. therefore, the ec-japan group is affected where it hurts most: industrial production. the deliberate shift from coal to petroleum and the accelerated growth rate of energy use has put all western countries (and for that matter the o rest of the world as well) in an awkward position because there is no possibility of substitution. the united states cannot very well stop the cars since no efficient substitute means of transporta- tion exists and europe cannot stop its industries though they run on petroleum energy. therefore, in the short-run, european and japanese indus- tries are much more vulnerable than american industries. of course, the industrial composition of each area is also important because some in- dustries such as asphalt, aluminum, and chemi- cals have a high input of energy (petroleum or indirectly electricity), while the manufacturing of household equipment and apparel have very little need of energy. there is a mitigating factor in all this because industries with high energy con- sumptions are also capital intensive. due to the very little use of labor, employment is not directly affected. but these industries may in turn affect the secondary industries that receive supplies, parts, and intermediate products from these pri- mary industries. as one would have expected, the industry hardest hit has been the automobile industry. this indus- try is based on , components i and has link- ages that directly or indirectly affect the entire economic system. in the united states, the short- age and the high price of gasoline have induced the american consumer to be more willing to drive a small car. but, the american car industry was unprepared for this change. this shift in con- sumer demand is providing a positive factor for the economy as a whole. the automobile industry is now investing hundreds of millions of dollars for conversion from manufacturing of large cars to small cars. this has a multiplier effect on the durable goods industries with shifts in the dis- tribution of employment but still not sufficient to trigger a depression. * professor of economics, northeastern university, boston, mass. and research associate, svimez, rome, italy. t major inputs, composition by weight: steel p.o.; iron p.c.; plastic and rubber . p.c. each; glass p.c.; aluminum and zinc . p.c. each; copper and lead p.c. each. intereconomics no. , o i l problems directly price-affected sectors europeans are more conscious of gasoline prices than americans. even in the past, european prices were always about double the prices of gasoline in the united states. therefore, cars tend generally to be smaller. but with the gaso- line shortage last winter the market demand for cars all but collapsed. some european econo- mists claim that car manufacturing can easily be switched to produce mass transit equipment. re- cently, agnelli of fiat stated that he is not going to switch to the manufacturing of mass transit transport equipment because there is no demand for such equipment. this is a sticky problem both in the united states and in europe. corporations produce those goods that will maximize profits, hence for which there is the most demand. de- mand for mass transit equipment is voiced through public sector, in general governments pay lip service to the need of conserving energy by using mass transportation, but do not allocate enough funds for accomplishing this, claiming depleted government resources and fear of fur- ther inflation. in the united states, for the last twenty years private enterprise with the government's tacit and sometimes overt approval managed to completely destroy most inter-city mass ground transporta- tion. to reconstruct even to the level of the 's would require billions of dollars. also, develop- ment of adequate mass transit would require other billions of dollars. for a while, as long as gas was difficult to obtain, policy makers and private economists forecasted a big development in mass transit, but minimum funds were made available by the government. the switch towards mass transit has diminished considerably now that gasoline seems plentiful again even at double the price of a few years back. it seems that mass transit will not be a national priority in america for a long while. in this respect, europeans and japanese are in much better position, even though recently, both france and italy increased their passenger railway rates considerably thus dimin- ishing somewhat the energy saving incentive to use inter-city mass transportation. another sector greatly affected by the shortage of petroleum is electricity. it is well known that besides households, most industries depend on electricity. the prospects of nuclear energy are still far off; the hopes we had during the 's have not yet materialized, because of high costs and not absolutely fail-safe conditions. shortages of petroleum should not be an impediment for producing electricity because modern plants are constructed to be able to switch from consump- tion of petroleum to consumption of coal almost instantaneously. this sort of conversion is mainly beneficial to the united states because it has high coal reserves. it is estimated that the united states has ample coal for about to one thou- sand years. japan is more affected than the us since it has neither coal nor oil resources. the mitigating factor for europe is that there are large deposits of coal in west-germany and england. the environment problems still remain. however, it was calculated that one barrel of petroleum equivalent of coal energy costs about six dollars when completely cleaned of pollutants. with pe- troleum selling at ten to thirteen dollars per barrel, coal has again become a competitor. but, the coal industry was not prepared. coal mines are in great part owned by the same petroleum companies that are at least partly to blame for the petroleum shortages. the coal producers claim that for the next ten years the demand for coal will not be sufficient enough in the us nor in europe to replace petroleum for electricity and industrial uses. international cost problems in the long run, the main problem is the problem of cost. we have evidence already of world-wide runaway inflationary trends. inflation in the united states is over p.c., the worst inflation since world war ii. between and only for a very few years did inflation in the united states ever exceed p.c. of course, in europe, inflation has been ranging from to p.c. or more throughout the 's. since last year, inflation in some ec-countdes and in japan is over p.c. the world-wide inflation experienced for the last year or so will continue to grow endangering world trade and finances. the growing restiveness of the third world will bring the cost of raw materials (including petro- leum) to levels not accessible especially to the third world. in addition, by a rachet process, prices of industrial products will accelerate at even a faster rate. a bushel of wheat increased four times over the last few years. we have to realize that the major producers of wheat, corn, and soybeans are the industrial countries and less so the third world. poor countries will have to pay higher prices for raw materials, for agri- cultural products and for industrial products. thus, the terms of trade will again favor the in- dustrial countries. countries such as italy and the uk, who import both raw materials and food products are experiencing more problems than the united states, a net exporter of primary and secondary products. this, however, is a short run problem because in the international market a new equilibrium will be reached in prices. in the process, a change in the industrial structure of many countries will occur and also in the eco- nomic relationship among various countries. most intereconomics no. , oil problems serious is that petroleum shortages may propel world hunger because as fertilizers and feed be- come more expensive, less food is available. the third world lacking mineral wealth is rapidly be- coming the starving fourth world. us - european relations at inflated prices, world trade has increased by about p.c. between - . world prices in- creased more than p.c. with prices of petro- leum and wheat increasing fourfold. grains and energy account for about half of the world trade. for the short run, terms of trade between europe and the united states are favorable to the latter. for example, last december it was thought that europeans would corner the us market for small cars. this did not happen because of the high prices of volkswagen type cars as compared with small us cars. europe and japan have been losing the competitive edge through the us de- valuation of and , and faster growing european inflation rates. the united states has also been gaining because of lesser problems of energy supplies. with a higher rate of interest in the united states than ever before, the short-term capital markets could attract european investors. it was expected that most europeans and oil producing countries would also be more evident in the united states stock market but the high interest rate does not favor equity portfolios. in addition, there are opportunities for direct investment in the united states. europeans and japanese could and did in fact purchase us farms to assure a ready supply of agricultural products. foreign purchases in us coal mines have taken place for a number of years. france, the netherlands, italy, and japan have already invested many millions of dollars in the us coal industry. the emerging hold of opec (organization of pe- troleum exporting countries) over the oil con- suming countries could give place to various scenarios for the immediate future and for the long run. for the short term (through ): [ ] funds (about $ bn) accumulated by the opec countries will be used in short term invest- ment on the eurodollar market. international liquidity will increase high inflationary pressures. this will not be as burdensome as some might fear because oil producing nations' new ready cash is still a small share of international equity. the equity of new york stock market exchange alone at the depressed prices of is worth $ trillion. [ ] the international energy demand that has been increasing at an annual rate of p.c. over the last decade will stabilize at levels or decline. the decline might stem from problems of balance of payments of some european coun- tries (uk, france, and italy) and japan, and an economic slow down. since the largest share of oil products in these nations are intended for in- dustrial use, any industrial decline will result in lower demand for petroleum. even at this writing (july ) the supply of petroleum products ex- ceeds demand by over a million barrels a day. [ ] prices of industrial products will increase fur- ther (on top of the p.c. over the last year) but this will still not allow the industrial oil consuming countries to recover some of their losses caused by skyrocketing oil prices. most industrial trade is among these developed economies. it would be different if the buyers of industrial goods were the oil producing countries. but, total demand for industrial goods from opec countries does not and could not amount for much in the near future. with prices skyrocketing, domestic demand in developed countries will slow down and therefore imports will, too. this will put strong pressure on oil prices. (saudi arabia may break away and lower prices by about $ or $ per barrel). since revenues are high enough for most oil producers, they might just slow down production. long-term perspectives for the long term (within a decade) the opec countries could strive for rapid industrial growth, speculate on world financial markets and squan- der their riches. under the best conditions and policies, given a proper political climate (no renewed fighting in the middle east and no internal upheaveis), the industrialization of arab oil countries (saudi arabia outproduces or can outproduce all other opec countries together) will be capital intensive such as investment in infrastructure, refineries, aluminum, steel, and petrochemicals. this would not upset the international market equilibrium. these products are not employment creating; therefore it does not matter if production is at abu dhabi or at rotterdam. indeed, to build up these basic industries, oil producing countries need purchase machinery, equipment, and tech- nology from oil consuming countries. these aqui- sitions will boost european and japanese export of durable goods and therefore strengthen the oil consumer economies. changes in international industrial structure will follow next. this can only happen if the inter- national demand of goods produced by basic in- dustries (steel, petrochemicals, etc.) is maintained and expanded. saudi arabia and kuwait can hardly consume the production of one integrated steel mill complex or aluminum plant. the non- intereconomics no. , oil problems oil producing less developed countries do not enter the picture because they are worse off than before october because of increased oil prices. the demand of basic industries' products essentially remains with developed economies for at least the next decade. thus, the well-being of opec countries depends directly on the well- being of the us, western europe, and japan. under the worst conditions, the scenario of spain's conquest of america in the th century can repeat itself. at that time spain accumulated huge quantities of gold that it used to buy goods and services from other western european coun- tries. this way the industrial revolution just by- passed spain leaving stagnation for another years. if the "black gold" is used today in the same manner, opec countries will never again get this opportunity. consumer countries will push ahead with oil sub- stitutes. even present technology allows this. at this time an oil barrel equivalent of "clean" coal cost between $ - and gas extracted from coal is quoted at even lower prices. success in re- search and development in low price substitutes will dictate the future price of oil. the interna- tional market will bear a price per barrel lower than its substitute, and it appears that it will be lower than today's posted price. on the demand side, a rapid shift to mass transportation, smaller cars and changes in the method of electricity production will relax the pressure on oil and might in the process scramble the opec coun- tries in competition to prices far below the prices of substitutes. at that time, to protect substitutes, governments of both consumer and producing countries will draw up a commodity agreement (such as for cocoa and coffee) to keep interna- tional prices above what the market would other- wise be. the neo-mercan.tilistic approach being adopted by some industrial countries can be self-defeat- ing. italy's new trade regulations may boomerang. the limitation in imports might hit exports. if japan, france, and the united kingdom follow suit - a probable alternative - international trade could decline to the dangerous levels that pro- pelled the world depression of the s. under these circumstances, the new international equi- librium will be reached when incomes will be lowered, prices will be high, and demand for manufactured goods will decline. a more hope- ful scenario is possible only through cooperation and planning among consumer countries to counterbalance the temporary powers gained by opec. journal of development studies volume eleven october number one rationalised mixed cropping under indigenous conditions: the example of northern nigeria david w. norman seasonal factors affecting nutrition in different age groups and especially preschool children s . m . schofield education and the development of farming in two areas of zambia n.r. vanzetti and j. e. bessell adjustments for trade distortion in project analysis deepak lal country size and trade concentration nadim khalaf stability of export earnings of developing nations hossein askari and gordon well a model of household saving behaviour with an application to the indian economy k.l. gupta discussion book reviews frank cass & co. ltd. great russell street, london wc b bt intereconomigs no. , doi: . /j.bbabio. . . s abstracts / biochimica et biophysica acta ( ) s –s core metadata, citation and similar papers at core.ac.uk provided by elsevier - publisher connector however, under a range of pathological conditions no levels can rise to micromolar levels and disrupt a wide range of cellular processes. between these two extreme concentration ranges no can interact with mitochondria in ways that have been described as physiological or pathophysiological. the highest affinity target is cytochrome c oxidase. this talk will review this interaction and suggest that it has the potential to play a role in both no signalling and detoxification. no has also been shown to interact with lower affinity with mitochondrial cytochrome c in both its reduced and oxidised forms. previous studies have indicated that no can oxidise cytochrome c at physiological ph. we show that most of this oxidation is not caused by direct reactions of no, but instead by a reaction product of no and oxygen, most likely no . in contrast the reaction of no with oxidised cytochrome c is a direct, reversible binding. intriguingly in the presence of cardiolipin no can also bind reduced cytochrome c with high affinity at neutral ph. we will describe these interactions and comment on their biological relevance. doi: . /j.bbabio. . . s / mitochondria and reversible apoptosis guy c. brown department of biochemistry, university of cambridge, uk e-mail: gcb@mole.bio.cam.ac.uk apoptosis has been considered as a form of cell death, to which a cell is irreversibly committed once cytochrome c is released from the mitochondria. however, apoptosis can also be regarded as a means of signalling to phagocytes, which may in principle be reversible up to the point of phagocytosis. we find that mitochondrial cytochrome c release does not inevitably commit a cell to death because if the cell reduces the cytosolic cytochrome c then caspase activation is blocked. similarly caspase activation does not inevitably commit a cell to death, because the caspases can be inactivated by endogenous oxidants. phosphatidylserine flip to the outer leaflet of the plasma membrane is also a reversible process, as long as phagocytes are not present to eat the cell. we find that many aspects of apoptosis are fully reversible in neurons. this leads to the conclusion that apoptosis can (in some circumstances) be reversible and is not always a form of cell death. doi: . /j.bbabio. . . s / ischemic preconditioning invokes multiple mechanisms of nitric oxide and reactive oxygen signaling at the mitochondrial level paul s. brookes department of anesthesiology, university of rochester medical center, rochester, ny, usa e-mail: paul_brookes@urmc.rochester.edu ischemic preconditioning (ipc) is a phenomenon in which short cycles of ischemia and reperfusion (ir) can protect organs such as the heart and brain from prolonged ir injury. mounting evidence suggests that both mitochondria and nitric oxide play critical roles in ipc signaling, although the exact biochemical mechanisms underlying cardioprotection are poorly understood. we have identified novel biochemical events involving reactive oxygen and nitrogen species, which may contribute to the modulation of mitochondrial function in ipc: ( ) s-nitrosation and reversible inhibition of respiratory chain complex i. ( ) activation of mild uncoupling via the generation of no derived electrophilic lipids (nitro-alkenes) and their post-transla- tional modification of mitochondrial carrier family proteins. ( ) endogenous generation of mitochondrial k+atp channel agonists and complex ii inhibitors, via redox reactions involving krebs' cycle intermediates. together, it is thought that these pathways all act to diminish mitochondrial ca + overload and ros generation at reperfu- sion, thereby limiting the opening of the permeability transition pore. a brief outline of the key findings in support of these novel signaling pathways will be discussed. doi: . /j.bbabio. . . (s ) mitochondria and reactive oxygen containing species symposium abstracts (poster and raised abstracts) s . mild uncoupling reduces oxidative stress in intact cells alexander m. wolf, sadamitsu asoh, ikuroh ohsawa, shigeo ohta department of biochemistry and cell biology, institute of development and aging sciences, graduate school of medicine, nippon medical school, japan e-mail: awolf@nms.ac.jp “mild uncoupling”, the introduction of a limited proton conduc- tance into the mitochondrial inner membrane, has been demonstrated to greatly reduce reactive oxygen species (ros) production in isolated mitochondria. on the other hand, it will also increase energy consumption to maintain the mitochondrial membrane potential, and cells need energy in the form of nadh to maintain the cellular protein machinery in the normal, reduced state. for this reason it has been a subject to debate whether mild uncoupling is a viable strategy to reduce oxidative stress in intact cells and ultimately in vivo, or whether the increased energy expenditure might have detrimental effects. using a redox-sensitive green fluorescent protein (rogfp ) targeted to mitochondria of pc cells, we found that mild uncoupling using low concentrations of chemical uncouplers fccp or dnp indeed reduced oxidative stress, whereas strong uncoupling caused oxidation of rogfp , indicating that the beneficial effects of uncoupling are limited to a certain range of membrane potential, and that uncoupling beyond this range will increase oxidative stress probably due to energy crisis. this leads to the conclusion that while mild uncoupling might be beneficial under some circumstances, it is a dangerous strategy since the safe range of uncoupling will probably depend on cell type and metabolic state. doi: . /j.bbabio. . . s . the role of reactive oxygen and nitrogen species in the pathogenesis of acute renal failure egor plotnikova, anastasia chupyrkinaa, alena vasilevaa, aleksandr kazachenkob, vladimir kirpatovskyb, dmitry zorova aa.n. belozersky institute, moscow state university, moscow, russia bresearch institute of urology, moscow, russia e-mail: plotnikov@genebee.msu.ru the aim of this work was to study mechanisms of acute renal failure (arf) development in kidney survived ischemia or mioglobi- nuria (rabdomyolysis). experimental model of those pathologies showed that days after ischemia or induction of rabdomyolysis, the levels of urea, creatinine and cell death markers increase. such kidney malfunctioning can be caused by tubular epithelium destruc- tion. in our experiments, lipid peroxidation products accumulated in kidney and total antioxidant activity of blood are decreased. also the level of nitrite in blood serum was increased indicating the activation of no production. analysis of ros- and no-production in kidney cells revealed amplification of the production of these radicals. we https://core.ac.uk/display/ ?utm_source=pdf&utm_medium=banner&utm_campaign=pdf-decoration-v http://dx.doi.org/doi: . /j.bbabio. . . http://dx.doi.org/doi: . /j.bbabio. . . http://dx.doi.org/doi: . /j.bbabio. . . http://dx.doi.org/doi: . /j.bbabio. . . mailto:gcb@mole.bio.cam.ac.uk mailto:paul_brookes@urmc.rochester.edu mailto:awolf@nms.ac.jp mailto:plotnikov@genebee.msu.ru book reviews alan hodgkin, chance and design: reminiscences of science in peace and war, cambridge university press, , pp. xi, , illus., £ . , $ . (hardback - - - ). just over forty years ago a revolution in biology was heralded by a series of papers in the journal of physiology in which alan hodgkin and andrew huxley described the membrane currents across the squid giant axon, analysed the underlying ionic mechanisms and derived a mathematical hypothesis of the nerve action potential that depended upon the external concentration of sodium ions. for their work they were awarded nobel prizes in and both subsequently achieved a parallel array of distinctions and honours: knighthood, the order of merit; mastership of trinity college, cambridge, presidency of the royal society. sir alan hodgkin's autobiography, an extension of a brief chapter written for the centenary of the physiological society in , now describes some of the scientific and personal background to that work. particularly poignant is the successful experiment, in plymouth in august , when he and huxley first recorded the potential difference across the axon membrane. within three weeks of that achievement, hitler invaded poland, and the technique was abandoned for eight years whilst the young physiologists were seconded to other duties. those intervening years provide a substantial component of this volume, as reflected in its subtitle. despite a strong quaker upbringing, a visit to nazi germany in the early s had stripped hodgkin of his pacifist beliefs, and he was eager to enter war service, not least because a demanding job would alleviate the frustration at having to abandon his nerve experiments. after a short spell in aviation medicine, hodgkin spent much of the war, like many other natural scientists, in radar research. his account supplements and illuminates several recent publications including radar days by e. g. bowen, whom hodgkin thought inspiring, incisive, but shabbily treated by the authorities; and echoes of war by sir bernard lovell, from whom hodgkin learned, amongst other valuable skills, the mysterious art of filling in air ministry requisition forms effectively. after the war hodgkin returned to cambridge, teaching and tutoring students on accelerated two-year courses, slowly re-building equipment and beginning experiments on crab nerves, behaving, as his wife wrote, like a dolphin suddenly released into the open sea. with huxley, recently demobbed from the navy, he worked on a hypothesis about the role of sodium ions in the generation of the action potential, work terminated by the energy crisis of the winter of which made laboratory conditions impossible for the experiments. in the spring of he managed his first post war trip to the marine laboratory, plymouth. here, in a badly damaged building, with squid in short supply and unsure of his rusty experimental technique, he started testing the hypothesis more rigorously, and by july hodgkin and huxley were able to give a short paper to the international physiological congress, announcing the sodium theory of nerve excitation, the first solid step towards stockholm. as the author suggests, a fictional account might finish with the successful conclusion of the scientific project begun so many years earlier. fortunately, sir alan provides a postscript: the nobel ceremony itself, after a curious false alarm two years earlier; the trip to stockholm three years later when his father-in-law, peyton rous, also won a nobel prize; the years as president of the royal society, especially the foreign visits to japan and china, the latter still in the throes of the cultural revolution; and the period as master of trinity, are all engagingly described. in both detail and generality this book gives a fascinating picture of an important facet of twentieth-century biomedical science, through the eyes of one of its most notable practitioners. the development of a nature-loving schoolboy into a mature professional scientist; the practical difficulties of experimental physiology, and the importance of finding the right question, the right collaborator and the right biological preparation are all emphasized, as are the responsibilities of science and scientists in wartime. e. m. tansey, wellcome institute available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core logan research group 	 	navigation 	 		 logan research group 	 	 	 	 		home 	main menu 	home 	research 	funded research 	mfcs and mets 	salinity gradient energy (sge) and thermal batteries 	x-mbrs 	trickling filters 	hbod 	particles 	bioadhesion 	perchlorate 	fungi 	teaching 	publications 	other publications 	books 	lab group 	former- students 	former postdocs 	former visiting scholars 	past group photos 	other photos 	presentations 	contact information 	 		 	 	return to content 	 	 	 			 	 	 researching technologies for an energy sustainable water infrastructure 	logan bioenergy lab, sackett room 	 	a cube microbial fuel cell (mfc) 	an array of mfcs 	a two-chamber, thermal regenerative ammonia battery 	battery electrode deionization 	graduation of mim rahimi and yaoli ye 	logan group spring 	logan labgroup 	on the basketball court (summer ) 	ismet conference at cornell 	ismet conference logan group 	ncec conference logan group ( in hangzhou) the main focus of the logan lab is the development of new renewable energy technologies, such as microbial fuel cells, for achieving an energy sustainable water infrastructure.  penn state news. additional work is underway to better understand the daily energy use in our lives, and how energy is captured and processed. the goal of this work is to develop pathways for energy consumption, and more importantly to shift our energy sources to renewable technologies. visit the daily energy unit d website. also, see some new presentations on daily energy use and water electrolyzers.   current research topics 	bioelectricity using microbial fuel cells (mfcs) and other applications. [summary] [mfc website]	biohydrogen production using microbial electrolysis cells. [summary] [website] 	 h production by water electrolysis using seawater (new! stay tuned). psu news story. psu news story. see also tv newstory 	 thermally regenerated batteries (trbs) to generate electricity using low-grade waste heat. [website] 	desalination or ammonia recovery using battery electrode deionization	 reducing fouling of reverse osmosis (ro) desalination membranes current funding: link to all funded projects in the logan lab.  other recent research topics membrane bioreactors:  for low-strength wastewaters (<~ mg/l of cod) hollow fiber membrane bioreactors that contain a high concentration of granular activated carbon (gac) can be used to effectively treat and filter wastewater. we have worked primarily with anaerobic membrane bioreactors, where the gac is kept suspended using recirculation, but also with micro-aerobic bioreactors where the gac is suspended by both air bubbles and recirculation. you can visit the xmbr page for information on these reactors, or more generally on membrane research at penn state. electricity from salinity gradients: the same technologies used for desalination can be modified and used for energy production. we are looking at using a new desalination technology developed in our lab called bdi with solutions of different salinities, such as freshwater and seawater, to produce electricity. there are many different types of salinity gradient energy technologies (sge), but the ones that are being researched in our laboratory include: bdi, reverse electrodialysis (red), capacitive mixing cells (capmix) to extract energy based on electrode capacitance, and concentration flow cell-based (cfc) batteries that use pseudo-capactive electrode reactions to extract energy as electricity. past research topics other research topics in the logan lab have included: particle dynamics, such as marine snow formation in the ocean, coagulation processes that produce fractal particles, and bioadhesion/bacterial transport in groundwater and filters; modeling of trickling filters; the development of a simplified measurement of biochemical oxygen demand call the hbod test; perchlorate remediation; the degradation of pollutants using white rot fungi; and molecular-scale techniques to study particle dynamics and microbial adhesion in engineered and natural systems. about bruce logan bruce logan is a member of the us national academy of engineering (nae), a foreign member of the chinese academy of engineering (cae), and a fellow of: the american association for the advancement of science (aaas), international water association (iwa), the water environment foundation (wef), and the association of environmental science and engineering professors (aeesp). he is a collaborator with kaust (saudi arabia), a former franqui international chair at ghent university ( , belgium); and a visiting professor at newcastle university (uk), tsinghua university, harbin institute of technology, and dalian university of technology (china). logan cv- - - . for citation information: logan google scholar- citations. 	 	 		 		 	 	 		 		 			© logan research group. all rights reserved. 		 		 			powered by wordpress. designed by 		 	 	 	 	 		 							skip to toolbar 						 					sites at penn state 	log in 	search 			 					 		 science for non-science majors ac - : science for non-science majors dr. robert m. brooks, temple university robert brooks is an associate professor of civil engineering at temple university. he is a fellow of asce. his research interests are engineering education, civil engineering materials, and transportation engineering. jyothsna k. s., jyothsna k. s., department of english, st.joseph’s college, bangalore, eecured a gold medal for the high- est aggregate marks in the post graduate english literature course at st.joseph’s college (autonomous). k. s. has been working for the department of english, st.joseph’s college for almost two years now, teaching both undergraduate and postgraduate courses in english. k. s. has published papers in intramu- ral and extramural publications and presented papers at several conventions, conferences, and seminars. mehmet cetin, temple university mehmet cetin is a doctorate candidate of civil engineering at temple university. he has master’s degree. his research interests are engineering education, civil engineering materials, and transportation engineer- ing. c©american society for engineering education, p a g e . . science for non-science majors abstract a certain level of scientific knowledge is needed for non-engineering and non-science majors because their success often demands effective use of and making informed decisions about scientific issues. this paper focuses on developing a strategy for providing non-science majors with a basic level of scientific knowledge for successfully dealing with real world technological issues. “the environment” course was taught in fall to non-science majors as a science core requirement using the traditional lecture method. this was the control group. an experimental group was taught in spring using four indices: ( ) learning from three hands on and minds on labs, ( ) using closer looks, ( ) case studies, and ( ) development of critical thinking abilities. the method of selecting these indices is explained in the paper. the average grade of the control group was % and that of the experimental group was %, a % improvement over the control group. the groups were significantly different with a calculated t value of . . the t-test confirmed statistical improvement at significant confidence level with an alpha value of . . the students ranked learning from three hands on and minds on labs. introduction scientific literacy can be defined as a broad range of knowledge about science and how humans develop, use and are affected by science. a certain level of scientific knowledge is needed for non-science majors because their success often demands effective use of and making informed decisions about scientific issues. non-major classes draw students from the arts, humanities, journalism, law, social sciences, and other disciplines. students are enrolled for two reasons: ) they're deeply interested in the subject or ) general education requirements force them to attend. the courses usually do not have prerequisites therefore while some students have extensive science backgrounds, others have none. it is a challenge for teachers of these courses to take into account the wide range of scientific knowledge of their students. non-science majors are faced with numerous forces that pull them in different directions— socialization, career, and scientific literacy. they are not well equipped to lead the nation, through its diversified and challenging problems by making informed decisions about issues such as industrial globalization, sustainability or alternative energy - . objective this paper focuses on developing a strategy for providing non-science majors with a basic level of scientific knowledge for successfully dealing with real world technological issues. p a g e . . motivation a certain level of scientific knowledge is needed for non-engineering and non-science majors because their success usually demands effective use of and making informed decisions about scientific issues. the authors believe it is important to help their students gain the knowledge and expertise necessary to make informed decisions about scientific issues. what is new in this paper? even though several universities and institutions have been working on these or similar issues, this study presents two new aspects: ( ) exact quantification of the improvements of the four performance indices supported by statistical data, and ( ) the way the four indices were integrated in teaching. methodology while learning about science, non-science majors need to gain expertise in the following four areas: ) science literacy, ) critical thinking ) problem solving, and ) understanding the role of science in society . . science literacy: students are taught how to read science newspaper articles by becoming familiarize with scientific jargon, data collection and interpretation through qualitative and quantitative reasoning. . critical thinking: students are taught how to ) distinguish between science, pseudo science, art, religion, and ) identify high, medium and low quality sources. . problem solving: students are taught different avenues of knowing the world by understanding that real world problems often are open ended. for example, students examine the impact time lag, non-linearity and irreversible consequences have on problem solving. . understanding the role of science in society: students are taught how to ) understand the connection between science and global issues such as global warming, energy sustainability, clean water, hunger, and disease and ) appreciate the necessity of funding scientific studies and education . “the environment” course was taught in fall to non-science majors as a science core requirement using the traditional lecture method. an experimental group was taught the above four areas in spring using four indices: ( ) learning from three hands on and minds on labs, ( ) using closer looks, ( ) case studies, and ( ) development of critical thinking ability. the four areas were properly balanced and applied in the four indices. the performance of the students was evaluated using a series of special assignments reflecting the four indices. the assignments accounted for % of the course grade. the grading formula for the control and experimental groups are shown in table . appendices , , and show examples of assignments that addressed critical thinking, case study, and closer look respectively . p a g e . . integration of four indices in teaching students were encouraged to refer to professional engineering and science journals and news papers when collecting data. they were discouraged from using hearsay and yellow journalism sources in their works. students were given ten exercises for each index. the following paragraphs give an example for each index. in the first and second steps index and are worked out. in the third step the knowledge gained in the first two steps is used. in the fourth step the first steps are used as feedback. step is fed into first two steps again. thus a continuous do-loop system is developed while each exercise is completed using all four indices. learning from a hands on and minds on lab the three hands on and minds on labs were: ) measuring ph, ) measuring sound, and ) measuring energy. measuring ph is considered in this example. the students are asked to become familiar with technical jargon such as aqueous solution, logarithm, molar concentration, hydronium ions, activating factor by reading newspaper articles. the technique for measuring ph is taught using hands-on experimental equipment and qualitative and quantitative reasoning. the students begin by using familiar liquids such as coca cola, sugar solution and drinking water. the instructor then explains the importance of ph in the formation of acid rain. students are taught that ) several decades of valuable time has been lost (time lag) in finding solutions for reducing acid rain; ) industrial air pollution (consisting of acid rain precursors such as sulfur dioxide, nitric oxide, and nitrous oxide) have caused irreversible damage; ) acid rain has reached increased disproportionately by following no-liner trend. students then learn how to use buffers to mitigate acid rain problems in bodies of water. they are provided with strategies to reduce air pollution, which contains acid precursors, thus reducing the acid rain problem. the goal is to increase students’ awareness of the necessity for funding strategies that mitigate air pollution with acid precursors. using closer looks this section deals with a closer look at the topic, “what does history tell us about global warming’s potential consequences for people?” the students are asked to familiarize themselves with the technical jargon (e.g. climatic systems, green house gases, climate models, anthropogenic climate change, ice-albedo feedback, intergovernmental panel on climate change) through extensive reading of science newspaper articles. projected carbon dioxide levels for the next two decades are worked out in the class using qualitative and quantitative reasoning. students are taught that ) several decades of valuable time has already been lost (time lag) in acting on solutions on global warming; ) fossil fuel burning has caused irreversible consequence of global warming; ) the global warming problem has reached a disproportionately larger size by following non-linear trends; ) strategies planned and implemented at personal, local national and world level can mitigate global warming. an appreciation of the necessity to fund strategies to reduce global warming is created. p a g e . . using case studies this section dealt with a case study on the topic, “measurement of carbon stored in vegetation. the students are asked to familiarize with technical jargon (e.g. carbon sequestration, long term carbon storage, kyoto protocol, carbon credits, terrestrial ecosystems, carbon sinks) by reading science newspaper articles. measurements of the amount of carbon stored in vegetation are worked out in class using qualitative and quantitative reasoning. students are taught that ) several decades of valuable time has already been lost (time lag) in acting for solutions on environmental problems such as global warming; ) capturing of long-term storage of carbon in forests, for the build-up of carbon dioxide (one of the principal greenhouse gases) in the atmosphere will reduce or slow by buying valuable time to address the ultimate challenge of reducing greenhouse gas emissions; ) deforestation has contributed to the irreversible consequence of global warming; ) the deforestation problem has reached disproportionately larger size by following non-linear trend; ) growing trees can throw a couple of cents in producing clean atmosphere. appreciation of the necessity for funding reforestation is created. development of critical thinking ability the issue is, “should wind turbines be installed in nantucket sound?”. the students are asked to become familiar with technical jargon (e.g. kinetic energy, mechanical energy, angular momentum, wind charger, auxiliary power, commercial electric power, wind power density, and renewable energy source) through extensive reading of scientific newspaper articles. students calculate electrical power from various real life scenarios using qualitative and quantitative reasoning. students are taught that ) several decades of valuable time was already lost (time lag) in acting on solutions for the world’s energy crisis; ) fossil fuel burning has irreversible consequences such as global warming; ) the energy crisis has reached a disproportionately large size by following non-linear trend; ) wind turbines can throw a couple of cents in producing clean and sustainable energy. appreciation of the necessity for funding wind turbines is created. method of selecting the indices at the beginning of the experimental group a list of common teaching tools were supplied to the students. they were asked to rank the tools. the top four were selected to teach the class. table shows the relative rankings of the teaching tools. results and discussion the average grade of the control group was % and that of the experimental group was %, a % improvement over the control group. the groups were significantly different with a calculated t value of . . the t-test confirmed statistical improvement at significant confidence level with an alpha value of . - . the students ranked “learning from three hands on and minds on labs” the highest as shown in table . in a written survey the students stated that they spent most of their time, interest and energy on this category. the students ranked “using closer looks” as the least important. this is probably due to the closer looks’ abstract nature of this index. table shows the statistical p a g e . . analysis of the four indices. % of the students’ written comments indicated that the integration of the four indices helped them learn the subject effectively. both the (experimental and control) groups were populated by % non-science majors. in both the groups, no student has taken any science course earlier. the prime author verified this fact. therefore, it is established that the improvement is due to teaching methods and not due to the composition of the background of the students. conclusions . the experimental group showed % improvement over the control group in obtaining scientific knowledge. . among the four indices the students ranked learning from labs the highest . these practices can be used in other science and engineering courses. the authors plan to use the strategy in two other courses over the next three years. the practices can be used in other courses or schools with appropriate modifications in order to help our students acquire the knowledge they need to make informed decisions about technology. bibliography . heywood, j ( ) learning adaptability and change. the challenge for education and industry. paul chapman/sage, london. . mina, m.; gerdes, r. m. “work in progress - a class called “how things work?” and its role intechnological literacy programs” fie’ frontiers in education, , th ieee - oct. pp. – . . department of labor ( ). learning a living. a blue print for high performance. the scans report) department of labor, washington, dc. . mentkowski, m. ( ). learning that lasts. jossey bass, san fransisco. alverno colle publishes ahandbook for students that is regularly reised called assessment at alverno. . green, s. ( ). analysis of personal transferable skills requested by employers in graduate recruitment advertisements in june , personal skills unit. the university of sheffield, sheffield. includes commentary on methods of teaching likely to achieve the objectives derived from the survey. see ref ch for a summary. . plummer j. and howard l. "engaging science, advancing learning" conference, november - , . aac&u's. . botkin, d., and keller, e. ( ) “environmental science,” th edition. john wiley & sons, pp , - , - . . haldar, a., and mahadevan, s. ( ). “probability, reliability and statistical methods in engineering design”, john wiley and sons, new york. . k uebler, r. and smith ( ). “statistics”, john wiley and sons, new york. . lipsey, m. w. ( ). “design sensitivity: statistical power for experimental research”. newbury park, ca, sage. p a g e . . table . grading formulas control group experimental group . regular assignments . special assignments . attendance and class participation . mid-term examination . final examination the indices component total p a g e . . table teaching tools and their relative ranks teaching tool relative rank learning from hands on and minds on labs, using closer looks, using case studies development of critical thinking ability. connection of educational objectives of the course to each lecture conducting in-class exercises conducting group discussions on various topics conducting debates for arguing pros and cons on selected topics assigning assignments for increasing analytical ability assigning assignments for increasing number crunching capability assigning assignments for increasing equation solving ability development of creativity p a g e . . table . improvement of the experimental group over the control group performance index control group (%) experimental group (%) improvement (%) rank ( ) learning from three hands on and minds on labs . ( ) using closer looks, . ( ) case studies, . ( ) development of critical thinking ability. . p a g e . . table . statistical analysis of performance indices performance index standard deviation t value control group experimental group ( ) learning from three hands on and minds on labs . ( ) using closer looks, . ( ) case studies, . ( ) development of critical thinking ability. . p a g e . . appendix critical thinking-wind turbines, yes or no? the critical thinking focuses on your recommendation whether wind turbines should be installed in nantucket sound? the wind turbines can supply electricity to approximately half a million of homes. however it has some adverse affects on fish habitats. ) give an example of cultural justification and utilitarian justification against the cape wind project ) list the reasons for and against the cape wind project. explain each reason. p a g e . . appendix critical thinking – what are the adverse results of global warning on people in the known history? . focus on medieval warm period and answer the consequences on viking explorers. . focus on medieval warm period and answer the consequences on people of the mayan civilization in the yucatan of mexico and central america, mono lake in california, and chaco canyon in new mexico. . focus on the little ice age period and answer the consequences on the people of western europe and north america. . explain how black plague is connected to the answer of question ? . what is the single most factor that is different between the answers of the four questions above and the consequences of global warming of toady and future? p a g e . . appendix critical thinking- how much carbon can be stored in trees? . comment on a massive worldwide program of tree planting for reducing global warming. . what is the role of estimate of error in predicting how much carbon is stored in a tree? your answer should focus on reduction of error by replacing guesses. . suppose you have old data with an estimate of error and new data without an estimate of error which one do you prefer to predict how much carbon can be stored in trees? p a g e . . the systemic risk of energy markets diane pierret université catholique de louvain & new york university th phd day, louvain-la-neuve systemic risk systemic risk: the risk of the financial sector as a whole being in distress and its spillover to the economy at large systemic risk is related to dependence, causality, externality, interconnectedness, spillover effects market integration, contagion, commonality shocks, crises, extreme events does this exist in energy markets? how to measure it? how does this affect the rest of the economy? / energy systemic risk energy systemic risk: the risk of an energy crisis raising the prices of all energy commodities with negative consequences for the real economy. increased dependence of the economy on energy increased energy market integration extreme energy market shock from the supply side negative consequences for the energy sector and the rest of the economy energy security: ”the uninterrupted availability of energy sources at an affordable price.” (iea) / related literature this project relates to the literature on past energy crises and the impact of energy prices on the economy (hamilton, ) systemic risk network (nier et al. ( ), battiston et al. ( ), billio et al. ( ), hautsch et al. ( ), diebold and yilmaz ( )) co-movements (billio et al. ( ), kritzman et al. ( ), acharya et al. ( ), brownlees and engle ( )) energy prices co-movements cointegration and causality in the mean (bunn and fezzi ( )) multivariate volatility (chevallier ( ), bauwens et al. ( )) copulae (benth and kettler ( ), boerger et al. ( ), gronwald et al. ( )) / outline the energy systemic risk measure: ensysrisk econometric methodology and application causility in means and variances factor model and tail expectations ensysrisk and the impact on the economy / outline the energy systemic risk measure: ensysrisk econometric methodology and application causility in means and variances factor model and tail expectations ensysrisk and the impact on the economy / ensysrisk the conditional mes of an energy asset (acharya et al. ( ), brownlees and engle ( )) is given by mesit = et− (rit |energy crisis) corresponding systemic prices are derived from past price levels syspriceit = pit− ∗exp(mesit ) ensysrisk: the total cost of an energy asset to the non-energy sector during an energy crisis ensysriskit = max( , syspriceit ∗wit ), where wit is the quantity exposure of the economy to asset i at time t. for an energy contract with maturity and delivery period ν, the exposure at time t is wit (ν) = ςi et− (fincons τ − inv τ ) for τ ∈ [t + ν; t + ν − ] / the mes of energy markets ( / ) energy crisis: an extreme positive energy market shock from the supply side mesit (c ) = et− (rit |renm,t > c , rm,t < ) , where renm,t is the energy market return, rm,t is the return of the non-energy sector, and c represents the var of the energy market at ( −α)%. an extreme increase in energy prices... not only oil prices: “while the security of oil supplies remains important, contemporary energy security policies must address all energy sources” (iea ) integration dimensions: underlying energy (oil, coal, natural gas, electricity, carbon), maturity/delivery, region futures prices / the mes of energy markets ( / ) methodology: the conditional mes as a function of mean, volatility and tail expectation mesit (c ) = et− (µit + σit uit |renmt > c , rmt < ) = µit + σit et− (uit |renmt > c , rmt < ) where µit and σ it are the conditional mean and variance of asset return i and uit = (rit − µit )/σit are the standardized residuals. separate causality from common factor exposure: causality in µit and σit heteroskedasticity and causality are removed to concentrate on the ’pure’ commonality or contagion phenomenon (forbes and rigobon ( ), billio and caporin ( )) common factors in standardized residuals: uit = f (yt , ζit ) / outline the energy systemic risk measure: ensysrisk econometric methodology and application causility in means and variances factor model and tail expectations ensysrisk and the impact on the economy / eex futures, energy spot and dax industrial indices eex futures electricity: phelix financial futures (m, q, y maturity) natural gas: gaspool physical futures (m, q, y maturity) coal: ara financial futures (m, q, y maturity) eu emission allowances: eua financial futures (y maturity) energy spot indices highly correlated to eex futures returns brent crude oil european coal eua dax industrial index (energy consumers) = non-energy index market areas netconnect germany (ncg): · open grid europe gmbh · bayernets gmbh · eni gas transport deutschland · grtgaz deutschland gmbh · gvs netz gmbh · thyssengas gmbh (planned in nd quarter ) gaspool: · gasunie deutschland · ontras – vng gastransport gmbh · wingas transport gmbh & co. kg title transfer facility (ttf): (planned in st quarter ) · gas transport services b. v. active trading participants on the eex natural gas market c o n n e c t i n g m a r k e t s natur al ga s m ar ke t a r ea s eex offers trading in natural gas on the spot market for the netconnect germany, gaspool and ttf (planned for st quarter ) market areas. on the derivatives market gas trading transactions can be concluded in the ncg and gaspool market areas. spot market derivatives market tr a din g p ar t ic ip ant s eex has been recording a continued positive trend as regards the number of trading participants: at the end of the year the number of trading participants in gas trading had increased to a total of comparing with companies at the beginning of the year. thus, eex is the gas exchange in continental europe with the highest number of trading participants. / / / / source: eex / outline the energy systemic risk measure: ensysrisk econometric methodology and application causility in means and variances factor model and tail expectations ensysrisk and the impact on the economy / cointegration and granger-causality in the mean augmented vector error correction model (vecm) for the joint mean of the (n ×t ) matrix of returns rt capturing cointegration, autocorrelation, causality, and seasonality rit = πi η�ln(pt− ) + k ∑ k= δ �ik rt−k + m ∑ m= θ �imxt−m + ϕ � i qt + εit where η are the cointegrating vectors, πi are error-correction parameters, δik is a (n × ) vector of autocorrelation and granger-causal parameters of order k, xt−m are exogenous variables lagged by m days and qt are deterministic (seasonal) factors. similar to bunn and fezzi ( ), except that all energy products are here considered to be endogenous variables (as part of the ’system’). / multiplicative causality garch model multiplicative causality garch model for the variance with a garch component and an interaction component εit = σit uit = � φit git uit where git = ( −αii −βi − γii ) + αii � ε it− φit− � + βi git− + γii � ε it− φit− � i{εit− < }, φit = f (u t− , ..., ui− ,t− , ui+ ,t− , ..., unt− ) li (t), i{εit− < } is a dummy variable equal to one when the past shock of asset i is negative, and li (t) is a deterministic function of time. in this application: φit = ci exp � n ∑ j= ,j �=i (ϑij ujt− + αij |ujt− |) + κ�i dt � where dt are deterministic terms including seasonal dummies. / networks of causal relationships causal relationships reflect physical relationships in the energy market (subsitution, merit-order) and spillover effects mean network variance network / outline the energy systemic risk measure: ensysrisk econometric methodology and application causility in means and variances factor model and tail expectations ensysrisk and the impact on the economy / factor model: dynamic pca dynamic pca based on the daily correlation matrices estimated with the dynamic conditional correlation (dcc) model ht = dt rt dt = dt � at Λt a � t + rζt � dt where dt = diag(σ t , ..., σnt ), at is a matrix of s eigenvectors associated with the s largest eigenvalues that are contained in the diagonal matrix Λt = diag(λ t , λ t , ..., λst ) with λ t ≥ λ t ≥ ... ≥ λst , s ≤ n and rζt is the correlation matrix of idiosyncratic terms ζt . standardized residuals uit = (rit − µit )/σit becomes a function of the first s dynamic principal components and idiosyncratic terms uit = s ∑ j= aijt yjt + ζit where aijt is the element of the eigenvector associated with asset i and principal component yjt extracted from rt , and ζit = uit −∑sj= aijt yjt . / restrictions on the dynamic pca the energy crisis condition is defined by factors: et− (uit |energy crisis) := et− (uit |renmt > c , rmt < ) the return on the non-energy sector: rmt � ymt = y t = a� t ut the energy market return: renmt � yenmt = y t = a� t ut restricted pca (ng et al. ( )): the st component is restricted to be the non-energy return (dax industrial index) maxa t a � t rt a t s.t. a � t a t = , ai t = ∀t,∀i �= dax industrial the other dynamic components are mutually orthogonal and orthogonal to the industrial component maxajt a � jt rt ajt s.t. a � jt ajt = , a � jt alt = ∀t,∀l �= j / tail expectations the non-energy market return: rmt � ymt = y t = a� t ut the energy market return: renmt � yenmt = y t = a� t ut the tail expectation et− (uit |energy crisis) is approximated by s ∑ j= [aijt et− (yjt |yenmt > c , ymt < )] + et− (ζit |yenmt > c , ymt < ) a nonparametric estimator of tail expectations is ê (yjt |yenmt > c , ymt < ) = ∑tτ= yjτ Φ �� yenmτ√ λenmτ − c√ λenmt � h − � i (ymτ < ) ∑tτ= Φ �� yenmτ√ λenmτ − c√ λenmt � h− � i (ymτ < ) where Φ(·) is the gaussian cummulative distribution function. the same estimation procedure applies to e (ζit |yenmt > c , ymt < ). / outline the energy systemic risk measure: ensysrisk econometric methodology and application causility in means and variances factor model and tail expectations ensysrisk and the impact on the economy / the conditional mes of energy assets mesit (c ) = µit + σit et− � s ∑ j= aijt yjt + ζit |yenmt > c , ymt < � . . . mes electricity . . mes natural gas . . . mes coal . . . mes carbon . . . mes brent / ensysrisk ensysrisk = the total cost in million euros of each energy commodity class to the german non-energy sector during a potential energy crisis ensysrisk electricity ensysrisk natural gas ensysrisk coal ensysrisk carbon ensysrisk brent / ’net’ impact on the economy mesmt (c ) = µmt + σmt et− � ∑sj= amjt yjt + ζmt |yenmt > c , ymt < � ’net’ impact of the energy crisis: ∆mesmt (c ) = mesmt (c )−mesmt (var(renmt ) . ) mes dax . mes dax . - - mes dax . mes dax . deltames dax - . - . - . . deltames dax / summary energy systemic risk: the risk of an energy crisis raising the prices of all energy commodities with negative consequences for the real economy ensysrisk: the total cost of an energy commodity to the rest of the economy during an energy crisis ensysrisk increases with high mes high prices high dependence of the economy on the energy source the mes captures co-movements in energy assets causal relationships in means and variances reflect possible spillover effects from one product to another tail exposure to common factors: the mes is conditional on extreme energy market shocks from the supply side (restricted dynamic pca) contact: diane.pierret@uclouvain.be / 	the energy systemic risk measure: ensysrisk 	econometric methodology and application 	causility in means and variances 	factor model and tail expectations 	ensysrisk and the impact on the economy the centre for science and environment in india notes, news & comments study programmes on organization of assistance in the event of major disasters. the task of establishing and standardizing the termino- logy relating to major disasters has been entrusted to the spanish delegation, which will present this proposal at the next meeting, to be held on and december in istanbul, at the invitation of the turkish government. the fifth informal meeting of the ministers might be held in greece, at the invitation of the greek government, which will be setting up a european pilot centre for forecasting earthquakes. the parliamentary assembly of the council of europe is following with especial interest the work done in the fields of forecasting and prevention of disasters, and also on cooperation between the states of southern europe—not only to forecast disasters, but also to protect and safeguard the cultural heritage. directorate of press and information council of europe b.p. r f- strasbourg cedex france. the centre for science and environment in india the centre for science & environment (cse) was set up in in new delhi as a non-profit, non-governmental, quasi-academic, research organization. its aim is to pro- mote public awareness of the role of science and technology in indian national development. more specifically, it ex- plores issues concerning environment and development in india. it was founded by anil agarwal, an indian institute of technology graduate who had worked as a journalist on 'the hindustan times' and the 'indian express' in delhi and as the assistant editor of the earthscan feature agency in london. most of the research and writing staff of the cse are science graduates or journalists. one of the first activities for the cse was to run a feature service for newspapers. in , it published the state of india's environment—a citizens' report, which for the first time examined not only different facets of the deter- ioration of the country's environment in painstaking detail but also established the interconnection between those dif- ferent facets. the report, published as a hardback volume of nearly pages, won acclaim in india and abroad, and has become the biggest single source of information on the country's environment. * being reviewed for our journal by dr m.s. swaminathan, frs, fna, director-general of the international rice research institute and president of iucn.-ed. note : we would like to commend this initiative most warmly and express the ardent hope that it will be emulated in more and more countries having similarly enlightened heads of government who are disposed to seek independent expert advice on pressing or foreseeable environmental problems.—ed. three years later, the cse followed up with a second report*, which covered new ground and dealt with new problems, and which included a long section on the causes and consequences of the bhopal gas-leak tragedy. it has already sold some , copies and is exactly twice as voluminous as the first book. like the first report, it has been widely extracted and reviewed in the indian and for- eign press. prime minister rajiv gandhi has recently asked the cse, on the basis of the second report, to brief the entire indian cabinet of ministers and all the members of parliament on the threat to india's environment. yet another publication of cse is temples or tombs? by the undersigned, which deals with three industrial projects that triggered off environmental controversies in the country. one of the remarkable features of cse's activities is that it has until recently been able to support itself almost entirely by the sales of its books. it is now working on others, two of which are to be entitled 'india's cooking energy crisis' and the 'state of india's urban environ- ment'. the cse also does networking on environmental issues with ngos in india and abroad. darryl d'monte, cse fellow centre for science and environment vishal bhawan nehru place new delhi india. energy from a fishpond falling oil prices make little difference to poor farmers in the third world whose resources cannot be stretched to buy power at any price and who, all too frequently, are remote from principal sources of supply. hence the interest of a unesco enterprise in paraguay, to develop a device for on-farm supplies of energy from biogas. the biogas is produced by the breakdown of aquatic plants from a fishpond. microorganisms work on the aquatic plants (which can be supplemented with animal manure) to decompose them in a biodigester {see caption to fig. ) in which organic matter is further decomposed. it is based on a chinese model, and yields around nine cubic metres of gas a day. integrating the installation with a fishpond has several advantages: it helps the farmer to raise his energy capacity with the biogas, and it also increases his foodstocks with fish from the pond, as well as supplying fertilizers and animal fodder from the aquatic plants. unesco's regional office for science and technology (rostlac) in montevideo helped to develop the system, which was designed by research workers at the institute of basic sciences in the national university at asuncion, led by dr r. fitzpatrick, a former unesco official. the installation has been set up at the enrique de osso college for the promotion of rural women in asuncion. the students, who come from inland regions of the coun- try, will spread the idea in their own villages. a training course for peasants together with instruction manuals are foreseen. https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core science american associwon for th advancement of scence science serves its readers as a forum for the presentation and discussion of important issues related to the advance- ment of science, including the presentation of minority or con- flicting points of view, rather than by publishing only material on which a consensus has been reached. accordingly, all ar- ticles published in science-including editorials, news and comment, and book reviews-are signed and reflect the indi- vidual views of the authors and not official points of view adopted by the aaas or the institutions with which the au- thors are affiliated. publishr: richard s. nicholson editor: daniel e. koshland, jr. new editor: ellis rubinstein mwnaging editor: patricia a. morgan deputy editors: philip h. abelson (engineering and applied sciences); john . brauman (physical sciences) editorial staff assistnt managing editor: nancy j. hartnagel senior editor: eleanore butz associat edtors: keith w. brocklehurst, martha coleman, r. brooks hanson, barbara jasny, katrina l. kelner, edith meyers, linda j. miller, phillip d. szuromi, david f. voss lettes editor: christine gilbert book review: katherine livingston, editor this week in science: ruth levy guyer contributing editor: lawrence . grossman chief production editor: ellen e. murphy editing department: lois schmitt, head; mary mcdaniel, patricia l. moe, barbara e. patterson copy desk: joi s. granger, 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( - - ); san jose, ca : bob brindley, s. th st. ( - - ); dorset, vt : fred w. dieffenbach, kent hill rd. ( - - ); damascus, md : rick sommer, kings valley dr. ( - - ); u.k., europe: nick jones, + ( ) ; telex ; fax ( ) . in maion for contributors appears on page xl of the march issue. editorial correspondence, including requests for permission to reprint and reprint orders, should be sent to h street, nw, washington, dc . tele- phone: - - . advwrtising crpondence should be sent to tenth floor, broadway, new york, ny . telephone - - or wu telex scherago, or fax - - . i april i volume number progress in energy r&d o ur present pattem of energy utilization will someday be substantially altered. impetus for change will arise from our inability to sustain continued increases in oil imports, or to mounting concerns about the greenhouse effect, acid rain, or urban pollution. four articles in this issue of science describe progress in developing technologies that may be helpful in responding to the next energy crisis. hubbard describes dramatic improvements in photovoltaic (pv) technology. scores of new pv materials and many new designs have been explored. as a result, the cost of pv electricity has dropped from $ per kilowatt-hour to about $ . per kilowatt-hour. to be competitive with future electric generations options, pv modules must exhibit solar energy efficiencies in excess of % at costs somewhere between $ . and $ . per kilowatt- hour. recent striking improvements in efficiency of conversion of solar energy to electricity and continued improvements in methods of manufacture indicate that this goal may be attained by the mid- s. a competitive solar cell industry has emerged, and substantial research is being conducted in a number of countries. burnett and ban describe ways in which prospects for natural gas have improved. the energy content of natural gas production in the lower states is already substantially greater than that of oil, and research and development have shown that methane occurs and is recoverable in many places in which oil is not present. examples include coal seams, shales, and deep formations. a recent u.s. department ofenergy reassessment ofthe resource base concluded that technically recoverable natural gas in the lower states is trillion cubic feet-a greater than -year supply at today's usage. natural gas is a clean fuel that gives rise to much less pollution than either coal or oil. in applications for cogeneration of electricity and heat, thermal efficiencies of % to % are achieved. the authors describe other new applications that guarantee an increasing role for natural gas in the u.s. energy mix. for example, the use of small amounts ofgas in coal-fired and waste-burning furnaces can lead to substantially decreased emission of pollutants. improvements in furnaces for home heating have made gas highly competitive with oil or electricity. ross discusses energy efficiency in industry. he points out that largely in response to the energy shocks of the s, u.s. manufacturers reduced their real fossil fuel intensity ratio of energy use to production by %. in the past decade there have been only sporadic improvements, and ross states that the cost-effective opportunity now available is very large. in addition to potential financial advantages, the technology of efficient energy use is improving rapidly. manufacturing is being revolutionized by introduction of new sensors coupled with electronic processing of information, followed by automatic control of processes. for example, equipment being installed in steel mills increases yields by controlling thicknesses during the rolling process. another development in industry is use of electricity in new applications where special advantages are achieved. that is, electric heating processes can achieve extremely high energy densities. in arc plasmas temperatures of , °c are routine. in almost every sector of industry pioneering methods of obtaining increased efficiency and energy savings are being implemented. if an energy crunch comes, these demonstrations will find energy-saving replications. the history of nuclear energy in the united states is a striking illustration of how a great nation can flub a major technological development. taylor states that the average capacity factor in the united states is about % as compared to % to % in some countries. in addition, u.s. operations and maintenance costs are averaging roughly twice what other countries spend. the u.s. utilities have now set goals to bring their average performance and cost effectiveness to a world competitive level while devoting top priority to safety. designs of three different reactor systems are moving ahead with five goals in mind: (i) assured safety with features that minimize consequences of human error, (ii) a significantly simpler design, (iii) high reliability throughout a lifetime of on the order of years, (iv) reduction in capital and other costs and a construction time of to years, and (v) a standard design that is predictably licensable.-philip h. abelson editorial i april i o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ progress in energy r&d philip h. abelson doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the is a registered trademark of aaas.sciencescience, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for the advancement ofscience by the american association for the advancement of science. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ influence of eustatic sea-level changes in oil and gas accumulations in appalachian basin: abstract; geothermal energy--viable energy resource: abstract association round table by important transcurrent components, but evidence for such components in the western united states is much less pro- nounced than in canadian and alaskan parts of the orogen. paleozoic, mesozoic, and early tertiary thrust faults in the southwestern united states display a distinct pattern of bilateral symmetry. in western parts of the orogen, thrust plates are char- acterized by a westward displacement relative to lower plate rocks and a westward decrease in age. thrust plates in central and eastern parts of the orogen are, with few exceptions, east- directed and show an eastward decrease in age. cordilleran thrust faults fall into three geographic and temporal groups, each of which can be characterized by a particular mode of plate interaction. east-directed thrust plates can be divided into two distinct groups—those in central parts of the orogen formed during the antler (devonian-mississippian) and sonoma (permian-trias- sic) orogenies, and those of younger age, generally in areas to the east. the antler and sonoma orogenies represent progressive stages in the closure of a marginal basin located between the continent and an offshore klamath-sierran island arc which developed in ordovician time. episodic closure of the basin oc- curred during times of accelerated plate convergence in the arc region. antler and sonoma allochthons consist of sedimentary and volcanic rocks from the marginal basin and slices of their oceanic basement displaced eastward across the continental shelf. closure of the marginal sea was accompanied by subduc- tion, probably eastward, of the bulk of the oceanic crust on which the basin fill had been deposited. complete closure result- ed in accretion of the island arc to the western margin of the continent. east-directed thrust plates of post-sonoma age are intraconti- nental, having developed within the north american plate, east of the andean-type mesozoic-early tertiary igneous complex. subduction-related magmatism produced a thermally controlled zone of high-crustal ductility along the western leading edge of the american plate. eastward intraplate yielding by thrust fault- ing was localized largely across the eastern boundary of this ductile zone as cooler, more rigid parts of the plate moved west- ward into and beneath it. the geometry of yielding also was influenced by stratigraphic anisotropy in thick sedimentary ac- cumulations (belt supergroup and cordilleran miogeosyncline). eastward migration of thrusting occurred in response to an east- ward shifting of plutonism and the zone of high-ductility con- trast. thrust faults in the western part of the orogen are products of eastward subduction of oceanic lithosphere, initially beneath the paleozoic klamath-sierran arc but also beneath the continental margin after triassic accretion of the arc to the continent. the westward shifting of these thrust faults from devonian through early tertiary time reflects westward shifting of subductive activ- ity by growtfi of melange wedges and accretion of oceanic and island arc rock assemblages to the continental margin. dennison, j o h n m., dept. of geology, univ. north caroli- na, chapel hill, n.c. influence of eustatic sea-level changes in oil and gas accu- mulations in appalachian basin regional stratigraphic studies indicate a minimum of eus- tatic sea-level fluctuations in the appalachian region from new york to alabama. a eustatic fluctuation is interpreted if the stratigraphic and sedimentologic records on two or more sides of the appalachian basin show evidence of a similar simultaneous shift in relative sea level within the limits of temporal resolution by fossils, intertonguing facies, or bentonite chronology. simul- taneous sea-level shifts affecting different lobes of ancient delta complexes built into the appalachian basin from eastern sources also are considered eustatic. for analysis of a hypothetical single basin, a eustatic sea-level change is one which affects the entire basin. the cause may be large-scale tectonics of the continental area containing the basin, or a true sea-level shift related to glaciation or rate of sea-floor spreading. timing on the sea-level variation curve is related closely to ages of strata with hydrocarbon production in the appalachian basin. changes in sea level result in shifting of sand deposition along shorelines, solution porosity in carbonate rocks exposed along basin margins, or modifications of reef growth. the clear- est relations to hydrocarbon production are in the well-explored oil and gas fields in the devonian and silurian, where the sea- level shifts can be used to explain permeability distribution. su- perposing sea-level shifts onto sedimentary tectonics in a basin of known shape allows prediction of exploration trends. the largest fluctuations of sea level are at the base of the sauk sequence (cambrian transgression), the owl creek discontinuity (base of the middle ordovician), the wallbridge discontinuity (end of the early devonian), and the discontinuity at the base of the absaroka sequence (beginning of pennsylvanian). fluctu- ations associated with the wallbridge discontinuity are related to deposition of the oriskany sandstone, which is the largest appa- lachian gas producer. lesser sea-level changes are related to other production, notably oil and gas from the upper devonian fields which were the birthplace of the american petroleum in- dustry, and gas from the silurian newburg sandstones. the eustatic sea-level curve from one basin such as the appa- lachian area should be compared with other basins to identify worldwide patterns and to help to focus petroleum exploration in distant basins. the major level drops at the end of the early ordovician, end of the early devonian, and the beginning of the pennsylvanian seem established. the sea-level drop in the appa- lachians at the end of the ordovician appears related to conti- nental glaciation centered in the african sahara. the rise in sea level at the end of the precambrian is possibly a result of an increase in rate of sea-floor spreading as the proto-atlantic ocean opened. recognition of true global changes should permit more precise intercontinental correlations because eustatic sea- level change is not related to distribution of faunal provinces or local tectonic processes. meidav, tsvi, geonomics, inc., hempstead, n.y. geothermal energy—viable energy resource interest in geothermal energy is increasing. in all countries which have been affected by the energy crisis, the quest for indigenous sources of energy which would reduce dependence upon importation of fuel has taken a tremendous surge. geother- mal energy is abundantly available along plate boundaries, as shown through examples from the united states, ethiopia, ken- ya, nicaragua, and indonesia. geothermal power plants are in operation in about half a dozen countries at a cost which is economically competitive with other forms of energy. the environmental impact of geothermal energy is especially low when it is used directly for heating or cooling. at the same time, geothermal heat is most attractive economically when used for nonpower uses. desalination and mineral extraction are other uses that may be made of geother- mal power. the total stored heal to a depth of . km is equivalent to million billion barrels of oil. this is equivalent to , mega- watt-years or miuion tons of oil per square kilometer of the earth's surface. even if only a very small fraction of the total resource base is ever utilized, it could provide energy equal to, or greater than, all currently known fossil-fuel reserves. examples of geothermal energy utilization from a number of countries are shown and discussed. meidav, tsvi, geonomics. inc., hempstead, n.y. emerging geothermal resources exploration technology exploration for geothermal energy requires reevaluation of existing exploration techniques and development of new ones. comparison research on different injection control strategy of ci free piston linear generator in one-time starting process energy procedia ( ) – available online at www.sciencedirect.com sciencedirect - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of icae doi: . /j.egypro. . . the th international conference on applied energy – icae comparison research on different injection control strategy of ci free piston linear generator in one-time starting process yu songa, huihua fenga*, zhengxing zuoa, mengqiu wanga, chendong guoa aschool of mechanical engineering, beijing institute of technology, beijing , china abstract in one-time starting process of ci free piston linear generator, the starting energy in one cylinder always influence the combustion process in the other cylinder. and the ignition delay has a great influence on the performance of the system running in the process. based on this influence, two strategies of injection controlling are proposed, which are triggered by displacement signal and velocity signal, respectively. with the strategy of injection triggered by displacement signal, the influence of injection position to mep, compression radio and other performance parameters of two cylinders are discussed. the velocity injection strategy utilizes the same model and the kinetic energy of piston assembly in different key position is considered as the impact indicator. this parameter and the injection time are interacted with each other, and they can influence the combustion performance of two cylinders. finally, this paper describes the applicability of two strategies and concludes that the strategy of injection triggered by velocity is more suitable for ci free piston linear generator in process of starting. © the authors. published by elsevier ltd. selection and/or peer-review under responsibility of icae keywords: free piston linear generator, injection strategy, starting process, ci . introduction after the industry revolution[ ], energy crisis were becoming increasingly prominent. at the same time many institutes were searching for a low emission and high efficiency system. free piston linear generator emerged in this situation. conventional internal combustion engine couples crank-link mechanism and flywheel inertial mechanism. complex structure contains lots of friction pair and energy storage device, which result in the high friction loss and low efficiency. compare to the conventional internal combustion engine, free piston linear generator has the advantages of high efficiency, low consumption, simple mechanism, good fuel adaptability and so on. in absence of flywheel or other inertia mechanism, this new type prototype has many unknown characters. the characters contain many potential advantages and * corresponding author. tel/fax: + - - . e-mail address: fenghh@bit.edu.cn. © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of icae http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf yu song et al. / energy procedia ( ) – uncertainties. especially the compression ignition (ci) prototype has less controlled parameters. only the injection time can be controlled, the top dead centre (tdc) of the piston is more difficult to predict. nomenclature abbreviation lc left cylinder rc right cylinder ldc left dead centre rdc right dead centre symbols x displacement of piston assembly[m] m mass of piston assembly [kg] fe electromagnetic force [n] ff friction [n] fl,r resultant of left or right engine [n] vl,r volume of left or right cylinder [m ] specific heat ratio qlc,rc heat transfer in left or right cylinder [j] . simulation methodology fig ci free piston linear generator dynamical model the model contains two diesel engines and a linear motor, it is shown in fig. . when the fplg system works, the fuel is injected into the compression cylinder of the prototype. in the state of high temperature and high pressure, the gas-oil mixture can burn and release heat. fuel gas expands to push the piston to work. according to first law of newton, dynamical equation of piston assembly is shown as: d d e f l r x m f f f f t in the starting process, substitution and mathematical manipulation yield the following equation which is used to calculate the in-cylinder pressure at each time step[ ]. d d d d d d lc lc l l l l p p v q t v t v t , d d d d d d rc rc r r r r p p v q t v t v t according to the working state in cylinders, the process of starting can be divided into stages. these stages contains starting processes and combustion processes as table shows. yu song et al. / energy procedia ( ) – table . the stages of the full process stage state in left cylinder state in cylinder starting compression adiabatic compression adiabatic expansion adiabatic compression exhaust adiabatic compression scavenge ignition delay scavenge ignition process combustion and compression scavenge combustion and expansion scavenge expansion without combustion exhaust expansion without combustion adiabatic compression exhaust adiabatic compression scavenge adiabatic compression scavenge ignition delay scavenge combustion and compression scavenge combustion and expansion . simulation results . . injection triggered by displacement signal this injection controlling strategy means the injection signal is triggered by displacement of the piston assembly. when the piston assembly moves to the default position, the displacement sensor can recognize the position and the signal can be transferred to trigger the injector of the compression cylinder. fig. . (a) motion characteristic in different right injection position; (b) motion characteristic in different left injection position the injection position on the right side is set various, and the motion and pressure characteristic profile is shown in fig. . (a). the key position of the piston assembly on the left side increases as the injection position changes from mm to mm, as a result, the maximum pressure in left cylinder increases from mpa to mpa. but when the piston moves to the right side, there is little variation of the key position because of the same injection position on this side. obviously, the hysteresis of the position can be seen. yu song et al. / energy procedia ( ) – as a contrast, the injection position on the left side is set various and the results are shown in fig. . (b), the variation trend of motion characteristic after position of rdc is opposite to the fig. . (a). . . injection triggered by velocity signal comparing to the displacement feedback, this injection controlling strategy means the injection signal is triggered by velocity of the piston assembly. in fig. . (a), the displacement and pressure of the key point are shown. with the velocity of injection time decreases, the hysteresis of position of ldc and rdc is not obvious. but the maximum pressure in cylinder in position of ldc rises remarkably. driven by the gas pressure, the maximum pressure in right cylinder reduces. this indicates that we can adjust the injection velocity of the two sides to control the combustion performance in cylinders. then the different injection velocity values are set in the simulation model, and the imep map of the lc and rc is shown in fig. . (b). the overall trend of the imep in lc is that it increases follow the increasing of the injection velocity of lc, but the imep of rc increases with the decrease of the injection velocity of the right side. the injection velocity of one side also influences the imep in another cylinder, but not the dominant factor. fig. . (a) motion characteristic and cylinder pressure in same injection velocity; (b) imep map in different injection velocity . conclusion this paper establishes the numerical simulation model based on the first law of newton, the second law of thermodynamics, and the law of conservation of energy. aimed at the starting process of ci free piston linear generator, two injection controlling strategy are provided and analysed. yu song et al. / energy procedia ( ) – with the increase of the lc injection position, the position of key points on right side postpones and decreases. but the rc injection position has the opposite influence. when injection is triggered by velocity, the maximum pressure in lc (starting cylinder) decrease with the enlargement of injection velocity of piston assembly. but the maximum pressure in rc (driven cylinder) increase. the imep of lc increases with the injection velocity of left side. but the imep of rc increases with the decrease of the injection velocity of right side. acknowledgements this research is funded by the national science foundation for young scholars of china (grant no. ). the research outcome is the result of a joint china-uk research program ‘ ’; and a uk- china research program funded by the engineering and physical sciences research council of the uk, global secure; and lh cogen funded by epsrc. references [ ] casba t n. linear engine development for series hybrid electric vehicles[d]. west virginia: west virginia university, [ ] shoukry e f. numerical simulation for parametric study of a two-stroke compression ignition direction linear engine[d]. west virginia: west virginial university, [ ] goertz m, peng l x. free piston engine its application and optimization[c]. sae paper, , - - [ ] mao j, zuo z, li w, et al. multi-dimensional scavenging analysis of a free-piston linear alternator based on numerical simulation[j]. applied energy, , ( ): - . [ ] mao j, zuo z, liu d. numerical simulation of a spark ignited two-stroke free-piston engine generator[j]. journal of beijing institute of technology, , ( ): - . [ ] mikalsen r, roskilly a p. a computational study of free-piston diesel engine combustion[j]. applied energy, , ( - ): - . [ ] mikalsen r, roskilly a p. the control of a free-piston engine generator. part : fundamental analyses[j]. applied energy, , ( ): - . [ ] mikalsen r, roskilly a p. the control of a free-piston engine generator. part : engine dynamics and piston motion control[j]. applied energy, , ( ): - . [ ] mikalsen r, jones e, roskilly a p. predictive piston motion control in a free-piston internal combustion engine[j]. applied energy, , ( ): - . impact factor . case studies journal issn ( - x) – volume , issue impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page non-performing loan and their effect on the economy author’s details: ( ) syed abdul sattar shah, asst. prof. iba university of sindh, jamshoro, ( ) tania mushtaque-phd student department of environmental,social and spatial change (enspac) roskilde university, , denmark. ( ) mushtaque jareeko-student of phd-institute for learning & philosophy / department of learning and philosophy aalborg universitet københavn / aalborg university copenhagen ac meyers vænge , .sal københavn sv ( ) faiz muhammad shaikh-assistant professor-szabac-dokri -muhammad shaoiab operation manager-ubl-jacobabad abstract this research paper deals with the basic concept of loans and non-performing loans (npls). the causes and consequences of non-performing loans, how these loans affect the economy of country and how these loans affect the liquidity of institutes? as we know that pakistan witnessed the bankruptcies in past, institutes like idbp, ndfc, picic went bankrupt. furthermore, the state bank of pakistan (sbp) maintains a comprehensive databank on ‘financial soundness indicators’ of all banks under its jurisdiction. in , non-performing loans to loans stood at . percent. by september , the same had increased to . percent. over the same period, non-performing loans have gone up from rs billion to a colossal rs billion, an increase of over percent in three years (saleem f, ). therefore, this research paper addresses the solutions and remedies for the institute that how to overcome the problem of npls. key words: npls, causes of npls, effect on economy . introduction no one can deny the importance of financial institutions in any developed or developing economy these financial institutions not only ease the credit flow in the economy but also enhance the productivity by revitalizing the investment (richard, ). investment is requirement for achieving economic growth. from a country’s prospective capital formation positively supports this investment function once a satisfactory level is achieved. the option of sound investment means flow additional capital in the future. the banking sector of an economy generally performs the core function which includes facilitation of payment system. mobilization of savings and allocation of funds to shareholders i.e. government, investor, consumer and business community, who may utilize them for the generation of economic activities. the banking sector can exert its positive influence by various segment of economy. the banking industry has been significantly affected by some crisis. one of the crisis that is faced by national and commercial banks and the dfis are non-performing loans(npls) as a result most of the financial institutions capital base was affected by increased losses from loans, defaults requiring them to seek recapitalization. economic growth in any country is not possible without a sound financial sector (rajaraman and visishtha, ). good performance of these financial institutions is the symbol of prosperity and economic growth in any country or region and poor performance of these institutions not only hamper the economic growth and structure of the particular region but also affects the whole world (khan and senhadji, ). in the last few decades we can see many banking failures all over the world (brownbridge and harvey, ), and due to these banking failures many banks have been closed by regulatory authorities (brownbridge, ). these banking failures negatively affect the economy in many ways, firstly these banking failures caused banking crisis by harming the banking sector, secondly it also reduces the credit flow in the country which ultimately affects the efficiency and productivity of the business units (chijoriga, ; brownbridge and harvey, ). according to brownbridge, ( ) many empirical researches have shown that most of the time banking failures or banking crisis are caused by non- performing loans. non-performing loans (npls) have gained world’s intention in the last three to four decades as these increasing non- performing loans are causing banking crisis which are turning into banking failures (barr and siems, ). non- performing loans are one of the main reasons that cause insolvency of the financial institutions and ultimately hurt the whole economy (hou, ). by considering these facts it is necessary to control non-performing loans for the economic growth in the country, otherwise the resources can be jammed in unprofitable projects and sectors which not only impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page damages the financial stability but also the economic growth. in order to control the non-performing loans it is necessary to understand the root causes of these non-performing loans in the particular financial sector (rajaraman and visishtha, ). it is important to understand the phenomena and nature of non-performing loans; it has many implications, as fewer loan losses is indicator of comparatively more firm financial system, on the other hand high level of non-performing loans is an indicator of unsecure financial system and a worrying signal for bank management and regulatory authorities, if we look into the causes of great recession - which damaged not only economy of usa but also economies of many countries of the world we find that non-performing loans were one of the main causes of great recession (adebola, wan yusoff, & dahalan, ). as high risk loans were granted to the unqualified borrowers and these loans were secured against overestimated resources or against nothing, and when this economic boom “went bust” those high risk loans turned into non-performing loans and as loans were given to unqualified borrowers those turned into non-performing loans, as a whole this collection of non-performing loans irrespective of its causes was one of the main factor of great recession which not only hampered the american financial sector but also economy of the whole world (clugston, ) as far as the banking system of pakistan is concerned it is facing a lot of problem like the banking sectors of other underdeveloped economies and the most destructive problem faced by the pakistani banking sector is the enormous amount of non-performing loans which not only harming the pakistani banking sector but also hampering country’s economy. objective of research following are the objectives of this research: to present the notion of non-performing loans to find the key determents of non-performing loans to find the effect of non-performing loans on economy to find the reason behind the merger of financial institutes with other institutions impact of amalgamations on country’s economy remedies to reduce the excess amount of non-performing loans . non-performing loans the deterioration in the quality of the loan portfolio of banks was the main cause of problems in the banking system and in financial crises in developed economies. indeed, the increase in loan defaults. the theme of "non-performing loans" (npl) has attracted more attention in recent decades. . therefore, the large amount of bad loans in the banking system generally results in a bank failure. most developing economies that undergo the process of financial liberalisation have banking systems that are burdened by a large proportion of bad loans and risky credits. the most common cause of bad loans is directed lending to preferred individuals or favoured sectors of the economy. these loans have created several problems for financial sectors and have seriously hindered the growth of developing economies. state-owned banks (sobs) rely on government interventions to protect them against their large risk exposures to the enterprises to which they have lent. that weakens their bargaining power and ability to control borrower. . non performing loans with respect to other conutries non performingloans of other countries are given below unitd kingdom has npls ratio of . in and in and germoney has . in and in .austerila has npl rati in was . and in . canada . and maximam in . .and npl ratio of pakistan in was . and in itsnpls ratio is . impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page if we through fully analayze the economic struture of pakistan right from separation today we can see obivious shiffling efforts, it also expands from extrem of nationalization to massive effort of privatization .the seed of privatization is not new to the policy makers of the country .history prolong more that year ago in pakistan industerial devlopment corporation was establish to boost up their managerial and production effort of more than industerial undertakings ,when it did not nourish . .goverment decided to sale these industries to private sector.second phase of privatization was when banker equity limited was privatized.and in year to oo are consider as rd phacse of privatization in this the commerical bank and national devlpment finance corporation ndfc were merge to national bank of pakistan .picic were held by other financial instituations. these hard decisions were taken by the state because of large proporatio of these non performing loans on their balance sheets. world bank provides data for pakistan from to . the average value for pakistan during that period was . percent with a minumum of . percent in and a maximum of . percent in . percent non-performing loans in pakistan reflects the health of the banking system. impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page the volume of non-performing loan is rising every year as we can see that non-performing loans of pakistani banking sector were rs. . billion and having infection ratio of . percent and these have risen to rs. . billion in march having infection ratio of . percent (state bank of pakistan, ). in order to reduce non-performing loans it is necessary to find the root causes of these loan a non-performing loan is a loan that is in default or close to being in default. many loans become non-performing after being in default for days, but this can depend on the contract terms. impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page “a loan is nonperforming when payments of interest and principal are past due by days or more, or at least days of interest payments have been capitalized, refinanced or delayed by agreement, or payments are less than days overdue, but there are other good reasons to doubt that payments will be made in full” (international monetary fund). it is typily bcy product of financial crisis because of non performing loans npls an investor may bring down his confidence in banking sector. in pakistan, non-performing loans are common in the agricultural sector where the farmers can't pay back the loan or the interest amount mainly as a result of losses due to floods or drought., during the year and pakistan witness the very high non-performing loans .the flood in pakistan has archanged the trend of non-performing loans (npls) as most of the npls are being reported from agriculture sector which may hurt the government’s as well as state bank’s move to persuade banks for greater participation for the recovery of agriculture sector the state bank estimates that food has displaced million people, devastated districts across the country, destroyed crops, livestock, roads, infrastructure while the direct losses to major crops was in the tune of rs unlike previous quarters, the increase in credit off-take was widely shared by different sectors of the economy. . . non-performing loans and their classification according to obamuyi ( ) a loan is considered to be as non-performing loan (npl) if its principal and markup is not being paid by the borrower in accordance with the agreed terms and conditions of loan payment. as far as pakistan is concerned non-performing loans are divided into three main categories by state bank of pakistan (sbp). according to the bsd circular no. dated rd june regarding the prudential regulations of state bank of pakistan, excluding agriculture loans, a loan whose principal or markup repayment is overdue for days is classified as “substandard”, the loan is classified as “doubtful” if being overdue for days and a loan is classified as “loss” if it is overdue for year. . a higher percent of such loans shows that banks have difficulty collecting interest and principal on their credits. that may lead to less profits for the banks in pakistan and, possibly, bank closures. the npl are among the main causes of the problems of economic stagnation. each impaired loan in the financial sector increases the possibility to lead company to difficulty and unprofitabilty the minimization of npl is a necessary condition for improving economic growth. when npl retained permanently, these will have an impact on the resources that are enclosed in unprofitable areas. thus, npl are likely to hamper economic growth and reduce the economic efficiency. causes and economic determinants of non-performing loans . energy crises energy is one of the most important components of development in any economy, irrespective of any sector of economy cheap and constant flow of energy is necessary for the development of economy of any country, because energy is an essential and complementary part of production (sahir and qurashi, , lee, ). as far as relationship of energy crisis and economic development is concerned there is a lot of empirical work has been done in the world and studies have found positive relationship (wolde-rufael, , lee, ). keeton and morris ( ) conducted a research in america to identify the factors which are causing non-performing loans in the banking sector of this country by taking the data from - and according to them bad performance of agriculture and energy sectors along with poor economic settings/conditions are the main factors causing non-performing loans, according to the authors energy crisis leads to bad loans in the economy. as far as pakistan is concerned it is facing energy crisis since as the production and distribution of energy (gas and electricity) has decreased rapidly and giving birth to long lasting energy crisis in the country (esp – , esp – ). these energy crisis have damaged the economy in many ways, energy crisis leads to reduction in production of firms and affects the revenues which ultimately leads to bad loans. energy crisis is one of the biggest problem faced by pakistan, due to this energy crisis (load shedding of electricity and impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page gas, high cost of energy and high cost of replacement resources of energy) has destroyed many industries of pakistan, these crisis have caused a huge amount of bad loans in the pakistani banking sector as these sick/closed business units are unable to pay their loan obligations. one objective of this research paper is to highlight this important determinant of non- performing loans in the pakistani banking sector . interest rate lending rates/ interest rates are one of the primary economic determinant of non-performing loans/bad loans. : lending rate is the bank rate that usually meets the short- and medium-term financing needs of the private sector. this rate is normally differentiated according to creditworthiness of borrowers and objectives of financing. the terms and conditions attached to these rates differ by country, however, limiting their comparability. the intrest rate of pakistan in was %. in it was at the peak point of %, and in it was %. is an empirical evidence of positive correlation between the interest rate and non-performing loans (nkusu ; adebola, yusoff, & dahalan, ; louzis, vouldis and metaxas, ; berge and boye, ). an increase in interest rate weakens loan payment capacity of the borrower therefor non-performing loans and bad loans are positively corelated with the interest rates (nkusu, ). as far as interest rate policy is concerned it plays very important role in npls growth rate in a country/economy, hoque and hossain ( ) examined this issue and according to them non-performing loans are highly correlated with the high interest rates which enhances the debt burden of the borrowers and causes loan defaults. espinoza and prasad ( ) examined the macroeconomic determinants of non-performing loans in the gcc banking system according to them high interest rates increases loan defaults but they did not find statistically significant relationship. bloem and gorter ( ) studied causes and treatment of npls, according to them frequent changes in the interest rate policy causes an increase in the bad loans. asari, et al. ( ) also found significant relationship between loan defaults and interest rates they also found that an increase in loan defaults also causes asset corrosion of banks and subsequently capital erosion. according to dash and kabra ( ) the banks with aggressive lending policies charging high interest rates from the borrowers incur greater non-performing loans. collins and wanjau ( ) also found interest rate as a primary factor boosting non-performing loans. impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page . economic conditions world bank definition: annual percentage growth rate of gdp at market prices based on constant local currency. aggregates are based on constant u.s. dollars. gdp is the sum of gross value added by all resident producers in the economy plus any product taxes and minus any subsidies not included in the value of the products. it is calculated without making deductions for depreciation of fabricated assets or for depletion and degradation of natural resources. growth in gross domestic product (gdp) there is a significant empirical evidence of negative association between growth in gross domestic product and non- performing loans (louzis, vouldis and metaxas , khemraj and pasha ( ), salas and suarina, ; rajan & dhal, ; fofack, ; and jimenez and saurina, ). if we look into the explanation of this negative relationship provided by the literature we find that growth in the gross domestic product usually increases the income which ultimately enhances the loan payment capacity of the borrower which in turn contributes to lower bad loan and vice versa (khemraj and pasha, ). . inflation world bank definition: inflation as measured by the consumer price index reflects the annual percentage change in the cost to the average consumer of acquiring a basket of goods and services that may be fixed or changed at specified intervals, such as yearly. generally there is an empirical evidence of positive relationship between the inflation in the economy and non-performing loans (khemraj and pasha, , fofack ). while nkusu, ( ) has explained that this relationship can be positive or negative according to the author inflation affects loan payment capacity of borrowers positively or negatively, higher inflation can enhance the loan payment capacity of borrower by reducing the real value of outstanding debt; moreover increased inflation can also weaken the loan payment capacity of the borrowers by reducing the real income when salaries/wages are sticky, moreover by highlighting the role of inflation in the presence of variable interest rate nkusu impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page further explains that in this scenario inflation reduces the debt servicing capacity of the loan holders as lenders adjust the lending interest rates to adjust their real return. in the inflation rate in pakistan was . . and in it was . , which was its maximum rate, and in the inflation rate reached at . . so according to literature relationship between inflation and non-performing loans can be positive or negative depending on the economy of operations. . unemployment there is an empirical evidence of positive relationship between unemployment in the economy and non-performing loans (nkusu, , vogiazas & nikolaidou , ; bofondi and ropele, ; berge and boye, ; rinaldi and sanchis- arellano, ; gambera, ). as far as theoretical explanation of this relationship is concerned an increase in the unemployment in the country negatively affects the incomes of the individuals which increases their debt burden, it is obvious when a person losses his source of income how he can return his loan, similarly an increased unemployment in the economy also negatively affects the demand of the products of firms which ultimately affects the production/sales of the firms, this ultimately leads to decline in revenues of the firms and a fragile debt conditions ( louzis, vouldis and metaxas, ). . exchange rate as far as relationship of the exchange rate is concerned literature provides mixed reviews. according to khemraj and pasha ( ) there is a positive relationship between real effective exchange rate and non-performing loans. an appreciation in exchange rates may have different implications i.e. it can adversely affect the loan payment capacity of export oriented firms (fofack, ) on the other hand it can positively affect the loan payment capacity of those borrowers who borrow in foreign currency, the relationship between nominal effective exchange rate (includes inflation) and non-performing loans is indeterminate. . developmental financial institution (dfis) and their role in economy of country the development financial institutions (dfis) were created in asian and other developing countries mostly after being the post- world war era. the dfis in the asian countries had greatly been supported by the international agencies such as the world bank and the asian development bank who not only extended lines of credit but also helped in the development of institutional framework and criteria for viable project appraisal. state bank of pakistan has also played a pioneering role to structure these financial institutions and was in the past responsible for providing rupee lines of credit. some of the dfis established in the country are listed impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page dfis are different from commercial banks by definition and scope of operations, the former assume the role of stimulating the development with emphasis on industrialization and growth of the economy or social objectives. most of the industries, small , medium, and large, in developing countries were financed by dfis. historically dfis in pakistan have common features; most of them were started with seed money from the government of pakistan and support from the international financial institutions. . . industrial development bank of pakistan: it was set up in . it was an important source which supplied the funds for development. it provided medium term and long term credit facilities. the loans were granted for the establishment of new industrial units and for the replacement needs of the old units. the major objective of this bank was to spread the benefit of industrialization in all the classes of the people. it issued the loans on behalf of the government and provided finance in the form of equity. it also encouraged the establishment of industries in the less developed areas of the country. it paid due regard to the export oriented industries and those industries which were based on domestic raw materials. it was also acting as a monitoring agency of world bank and asian development mostly after being the post- world war era. . . pakistan industrial credit and investment corporation (picic): the pakistan industrial credit and investment corporation were established in with the help of government of pakistan and world bank. the private domestic investors held % shares and the remaining % was taken by foreign investors from japan, uk, west germany and . . investment corporation of pakistan: it was set up in . its major objective was to develop the capital market in the country. the corporation had floated mutual funds and a state enterprise mutual fund with a view to offer opportunities of pooled investment to investors. the corporation's market transactions for its own portfolio, investors' portfolio and mutual funds' portfolios contributed towards strengthening activity on the stock markets. impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page . . national investment trust (nit): the nit was set up in as a trust. it has acted as an open end mutual fund it was established to mobilise the savings to invest in stock exchanges. . . equity participation fund (epf): it was established in . its major objective was to improve the growth of small and medium size industry in the private sector. it had given priority to the less developed area. . . banker's equity limited: it started functioning in . its objective was to improve the private sector investment and capital market. . . small business finance corporation: it was set up in . its main aim was to provide financial aid to the small business to increase the rate of production and employment in the country to those people who had some technical know-how but they were financially poor. . . house building finance corporation: the house building finance corporation now known as house building finance company limited) was established in to promote mortgage finance in the country. . . pakistan industrial development corporation of pakistan (pidc): this was established in with the sole objective to promote industrialisation of the country .it was created to establish various industries and then resale these to the private sector. . . agricultural development bank of pakistan (zarai tarqiati bank): the zarai taraqiati bank limited (ztbl) (formerly known as agricultural development bank of pakistan) is the largest public sector financial development institution. this was established in . . role of devlopment financial instituation in economic devlopment of conutry these dfis were major channels for routing development funds to the private manufacturing sector and achieving the desired socio-economic objectives, such as encouraging new entrepreneurs, promoting industries in less developed areas and wider diffusion of industrial ownership. the dfis were also assisting the government in screening new development projects, framing economic development plans or policies, rehabilitating sick or problem projects, administering or supervising special loans provided by the government or foreign institutions and participating in the promotion of other dfis for achieving related socio-economic objectives. besides promoting establishment of import-substitution industries, the dfis encouraged capital formation by directly investing or underwriting shares and debentures issued by the local companies. they also assisted pakistani entrepreneurs in obtaining suitable foreign investment, attracting foreign investors in formation of joint ventures with local partners and assisting in obtaining technical / managerial advice for businesses and industries. many industries were made operational, enormous jobs were created both in the operational and service sectors and the country was on the road to economic and social progress. however many dfis ran into problems stemming basically from poor management and excessive loans without proper due diligence. unlike the cases of certain commercial banks, neither there were efforts to inject fresh equity or soft loans into problem dfis, nor there was a serious attempt to restructure them. the problem dfis, were merged into other dfis/commercial banks or were liquidated. impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page pakistan, still a low income, developing country, badly needs the services and facilities offered by the dfis for achieving socio-economic objectives and well-being of the people, particularly in the underdeveloped areas. in pakistan, idb pand pcici were two premier dfis at a time when we in pakistan had dfis like picic and ndfc. unlike pakistan, the role of these two institutions has been substantially enlarged over the period. in order to further enforce their role, to supplement their low cost funding sources and enhance their profitability they were granted licenses for commercial banking business. both the institutions were restructured to keep them in line with changing market conditions. idbi bank and icici bank are profitably financing infrastructure and other development projects in india whereas we have allowed picic and ndfc to whither away. the financial sector in pakistan comprises of commercial banks, development finance institutions (dfis), m currently following dfis are being regulated by state bank of pakistan. - pak burnicompany limited -- pak china investment company limited -- pak iran (pair) investment company limited -- pakistan kuwait investment company limited -- pal libya holding company limite - pak oman investment company limited -- saudi pak industrial and investment company limited the above development finance institutions (dfis) operating in pakistan are all joint ventures between the government of pakistan with governments of saudi arabia, iran, brunei, kuwait, libya, china and oman. both pak- china investment company and pak-iran investment company are relatively newer dfis, having started their operations as recently as . these dfis operate under the broad objective of facilitating investment in the country and improving bi-lateral relations. key financial indicators of dfis are presented in the table given below. in , despite the slow economic activities in the country, aggregate assets of dfis grew by . percent to rs . billion, as against negative growths in the previous two years. this growth was largely broad based where almost all dfis showed significant improvement in their assets (average growth percent) in . impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page sector wise contibution of npl of dfis impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page . . national development finance corporation national development finance corporation (ndfc) is based karachi, sindh, pakistan was founded by zulfikar ali bhutto. national development finance corporation is the largest development finance institutio of pakistan performing diversified ait was set up as a joint venture of national development finance corporation (ndfc), international finance corporation (ifc), asian development bank (adb) and the private sector.ctivities in the field of industrial financing and investment banking. national development finance corporation in pakistan in its merchant banking and project finance divisions. national development finance corporation is the largest development finance institution of pakistan performing diversified activities in the field of industrial financing and investment banking. it was established through an act of parliament in to finance public sector industrial enterprises but, later on, its charter was modified to provide finance to the private sector as well. the corporation's resources consist of funds generated through its own deposit schemes, lines of credit from the state bank of pakistan and multilateral credit agencies. besides providing term finances, it also provides diversified banking services, including lease financing, consultancy services, underwriting of public issues and impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page equity support as well as working capital finance (wcf). during the last five years, - , ndfc credit volume increased from rs. , million to rs. , million which gives an annual compound growth rate of . per cent. profit before provisions during enhanced to rs. . million showing an increase of rs. . million over the preceding year. . . contribution to national development economic import of ndfc-financed projects:- *$projects assisted by the corporation have continued to make a significant contribution to the country's economic development in terms of value-added,foreign exchange earnings/savings and additional employment opportunities. in aggregate terms, projects financed by ndfc have contributed rs. , million to pakistan's gdp and generated rs. . million after-tax profits and , jobs. * ndfc is actively engaged in the identification and promotion of new indigenous, and transfer of, technology and in this respect it has organised conferences in association with international agencies and has also conducted a number of studies on engineering, plastics, electronics, paper, sugar, leather textiles etc. . . . promoting local technology currently major parts of sugar and cement plants are being manufactured in pakistan and they have provided financial assistance for the export of sugar plants to bangladesh and indonesia. similarly, ndfc has provided assistance to export engineering goods against credit provided by the multilateral institutions. . . . private sector energy development fund * ndfc on behalf of government of pakistan is administering the private sector energy development fund (psedf) since - a pool of resources amounting to us $ million. additional funding of us $ million is expected to be available during . the co-financiers of the fund, besides the world bank, the export import bank of japan and usaid/usex bank, includes the governments of france and italy, the nordic investment bank, the overseas development agency of uk etc. * substantial progress has been made on the execution of hub power project, the largest thermal power project in the private sector with a capacity to produce , mw power per year. the world bank in february, cleared the ndfc appraisal report for the project and in april a loan agreement of us $ million was signed between ndfc and hub power company (hubco) and approval given for us $ million as mobilisation payment. in addition to the foreign currency loan ndfc has sanctioned advance out of its own resources and is arranging a syndication of rs. . billion from the local market. . . . domestic resource mobilisation ndfc mobilises its own local currency resources. the funds generated through its various deposit schemes, constituting ndfc's single largest local currency resource, have increased to rs. . billion. this service was a great innovation and has been copied by a large number of institutions all over the world. . . . development of capital marketing pakistan ndfc has made a significant contribution in the development of capital market in pakistan. the corporation as a consultant/agent of water and power development authority (wapda), successfully floated long-term bonds of over rs. . billion from the local market during and . moreover, in order to develop a secondary market for the bonds, ndfc has established the first credit and discount corporation (fcdc) to provide discounting facilities for the wapda bonds. ndfc is the first pakistani financial institution to have floated a privately-subscribed bond in a foreign capital market and raised japanese yen . billion in (us $ . million). impact factor . case studies journal issn ( - x) – volume , issue http://www.casestudiesjournal.com page during eighties ndfc has promoted a number of financial institutions. among others. the regional development finance corporation (rdfc), the national development leasing corporation (ndlc) and capital modaraba and the youth investment promotion society (yips) are good names which have created a lot of impact on the pakistan economy. in pursuance of the prime minister's programme for the promotion of computer literacy in the country, ndfc has established a most modern computer training institute at nawabshah, which was inaugurated by the prime minister benazir bhutto on july , . this institution has been established with the most modern software tools, using state- of-the-art hardware computer training. the institute will be a centre of high excellence where highly educated and experienced professionals are imparting training. ndfc has a number of competitive advantages - range of product line, extent of reach through its branch network, correspondent relationships, consultancy services etc. all the available resources will be effectively leveraged to bring in more and better business in the coming years. however, with the changed economic environments emerging from de- regulation of the financial market, there is, a need for innovation in the services being provided and developing new lending instruments. the ndfc is currently the largest development finance institution of pakistan performing diversified activities in the field of industrial financing and investment banking. projects financed by ndfc have contributed rs. , million to pakistan's gdp and generated rs. million after-tax profits and , jobs.by the mid- s ndfc had a pool of resources amounting to us $ million the bhutto government increased the level of investment, private and public, in the economy from less than rs. , million in – to more than rs. , million in role of ion channels in ionizing radiation-induced cell death biochimica et biophysica acta ( ) – contents lists available at sciencedirect biochimica et biophysica acta journal homepage: www.elsevier.com/locate/bbamem review role of ion channels in ionizing radiation-induced cell death☆ stephan m. huber a,⁎, lena butz a,b, benjamin stegen a, lukas klumpp a, dominik klumpp a, franziska eckert a a department of radiation oncology, university of tübingen, germany b department of pharmacology, toxicology and clinical pharmacy, institute of pharmacy, university of tübingen, germany ☆ this article is part of a special issue entitled: membra cancers. ⁎ corresponding author at: department of radiation on hoppe-seyler-str. , tübingen, germany. tel.: + e-mail address: stephan.huber@uni-tuebingen.de (s.m http://dx.doi.org/ . /j.bbamem. . . - /© elsevier b.v. all rights reserved. a b s t r a c t a r t i c l e i n f o article history: received july received in revised form october accepted november available online november keywords: ion transport radiation cancer cell death therapy resistance ca +-activated k+ channels neoadjuvant, adjuvant or definitive fractionated radiation therapy are implemented in first line anti-cancer treatment regimens of many tumor entities. ionizing radiation kills the tumor cells mainly by causing double strand breaks of their dna through formation of intermediate radicals. survival of the tumor cells depends on both, their capacity of oxidative defense and their efficacy of dna repair. by damaging the targeted cells, ionizing radiation triggers a plethora of stress responses. among those is the modulation of ion channels such as ca +- activated k+ channels or ca +-permeable nonselective cation channels belonging to the super-family of tran- sient receptor potential channels. radiogenic activation of these channels may contribute to radiogenic cell death as well as to dna repair, glucose fueling, radiogenic hypermigration or lowering of the oxidative stress bur- den. the present review article introduces these channels and summarizes our current knowledge on the mech- anisms underlying radiogenic ion channel modulation. this article is part of a special issue entitled: membrane channels and transporters in cancers. © elsevier b.v. all rights reserved. contents . introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . radiotherapy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . radiosensitizing ion channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ion channels conferring intrinsic radioresistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ion channels in acquired radioresistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . concluding remarks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . introduction ionizing radiation kills or inactivates cells mostly by damaging the nuclear dna and cell survival critically depends on successful repair of the dna damage [ ]. ionizing radiation may lead to necrotic as well as apoptotic cell death depending on cell type, dose and fractionation pro- tocols [ ]. the major death pathway in this scenario in normal tissue cells is apoptosis. however, cancer cells which often have developed strategies to evade apoptosis [ ] may either undergo (regulated) necro- sis or reenter the cell cycle with accumulated dna damages. during the ne channels and transporters in cology, university of tübingen, . . huber). subsequent cell divisions those cells will not be able to segregate the chromosomes and end up as multinucleated giant cells in mitotic catas- trophe. mitotic catastrophe again leads either to apoptotic or necrotic cell death. another possible mechanism of radiation-induced death in cells with disturbed apoptosis machinery is excess autophagy. while autophagy is a survival strategy [ ] excess autophagy overdigests the cytoplasm and cell organelles forcing the cell into apoptosis or necrosis [ ]. meanwhile, the evidence is overwhelming that ion channels fulfill pivotal functions in cell death mechanisms such as apoptosis (for review see the article by annarosa arcangeli in this special issue on “membrane channels and transporters in cancers”) as well as in stress response and survival strategies. notably, tumor cells have been dem- onstrated to express a set of ion channels which is different to that of the parental normal cells. these channels may fulfill specific oncogenic functions in neoplastic transformation, malignant progression or tissue http://crossmark.crossref.org/dialog/?doi= . /j.bbamem. . . &domain=pdf http://dx.doi.org/ . /j.bbamem. . . mailto:stephan.huber@uni-tuebingen.de http://dx.doi.org/ . /j.bbamem. . . http://www.sciencedirect.com/science/journal/ www.elsevier.com/locate/bbamem s.m. huber et al. / biochimica et biophysica acta ( ) – invasion and metastasis (for review see [ ]). in addition, they may con- tribute to the cellular stress response for instance during fractionated radiation therapy and may confer radioresistance. the present review intends to sum up data on ion channel function in the stress response to ionizing radiation. in particular, ion channels that may induce cell death in tumor cells and facilitate radiogenic cell killing are introduced. in addition, data on ion channels which, in con- trast to the before mentioned, confer radioresistance are reviewed. finally, ion channels of tumor cells that might contribute to acquired radioresistance, e.g. by promoting radiogenic hypermigration or transi- tion into relatively radioresistant cancer stem (cell)-like cells (cscs) are described. prior to that, a brief introduction into radiotherapy and its radiobiological principles is given in the next paragraphs. . radiotherapy radiation therapy together with surgery and systemic chemothera- py is the main pillar of anti-cancer treatment. about half of all cancer patients receive radiation therapy, half of all cures from cancer include radiotherapy [ ]. despite modern radiation techniques and advanced multimodal treatments, local failures and distant metastases often limit the prognosis of the patients, especially due to limited salvage treatments [ ]. ionizing radiation impairs the clonogenic survival of tumor cells mainly by causing double strand breaks in the dna backbone. the num- ber of double strand breaks increases linearly with the absorbed radia- tion dose. the intrinsic capacity to detoxify radicals formed during transfer of radiation energy to cellular molecules such as h o (giving rise to hydroxyl radicals, ˙oh) and the ability to efficiently repair dna double strand breaks by non-homologous end joining or homologous recombination determines the radiosensitivity of a given tumor cell. irradiated tumor cells which leave residual dna double strand breaks un-repaired lose their clonogenicity meaning that these cells can not restore tumor mass (for review see [ ]). in addition to these intrinsic resistance factors, the microenviron- ment may lower the radiosensitivity of tumor cells. hypoxic areas are frequent in solid tumors reaching a certain mass. tumor hypoxia, how- ever, decreases the efficacy of radiation therapy [ ]. ionizing radiation directly or indirectly generates radicals in the deoxyribose moiety of the dna backbone. in a hypoxic atmosphere, cellular thiols can react with those dna radicals resulting in chemical dna repair. at higher oxygen partial pressure, in sharp contrast, radicals of the deoxyribose moiety are chemically transformed to strand break precursors [ ]. by this mechanism, hypoxia increases radioresistance by a factor of two to three (oxygen enhancement ratio) [ ]. fractionated treatment regimens which improve recovery of the normal tissue after irradiation but not of the tumor have been established in radiotherapy [ ]. in addition to limit normal tissue tox- icity, killing of tumor mass by initial radiation fractions has been dem- onstrated to reoxygenate and thereby radiosensitize solid tumors during further fractionated radiotherapy. beyond that, fractionated radiation regimens aim to redistribute tumor cells in a more vulnerable phase of the cell cycle in the time intervals between two fractions [ ]. accelerated repopulation of the tumor after irradiation is a frequently reported phenomenon. possible mechanisms of accelerated repopula- tion include induction of cscs: it has been proposed that radiation ther- apy induces cscs to switch from an asymmetrical into a symmetrical mode of cell division; i.e., a csc which is thought to normally divide into a daughter csc and a lineage-committed progenitor cells is induced by the radiotherapy to divide symmetrically into two proliferative csc daughter cells. this is thought to accelerate repopulation of the tumor after end of radiotherapy. importantly, cscs are thought be relatively radioresistant possibly due to i) high oxidative defense and, therefore, low radiation-induced insults, ii) activated dna checkpoints resulting in fast dna repair, and iii) an attenuated radiation-induced cell cycle redistribution [ ]. finally, fractionated radiation therapy, which applies fractions of sublethal radiation doses (usually gy per fraction), has been demon- strated in a variety of tumor entities in vitro and in animal models to stimulate hypermigration and hypermetastasis of tumor cells as well as infiltration of the tumor by cd b-positive myeloid cells and subse- quent vasculogenesis. it is tempting to speculate that radiogenic hypermigration boosts cellular interaction of tumor cells with non- tumor cells, e.g. endothelial cells. it has been proposed that cscs lodge within perivascular niches where a complex regulatory network supports csc survival [ ]. as a matter of fact, cscs but not non-cscs gain radioresistance when transplanted orthotopically in mice [ ] supporting the idea of a tumor microenvironment-dependent acquired radioresistance. ion channels contribute to both, intrinsic and acquired radioresistance of tumor cells as discussed in the next paragraphs . radiosensitizing ion channels member of the melastatin family of transient receptor potential channel (trpm ) is a ca +-permeable nonselective cation channel. heterologous expression of trpm in human embryonic kidney cells [ ] or a human glioblastoma cells [ ] facilitates oxidative stress- induced cell death. reactive oxygen species (ros) have been demon- strated to trigger trpm activation [ , ]. the principal activator, however, of trpm is adp-ribose (adpr) that binds to a special domain located at the c-terminus of the channel [ , ]. sources of adpr are the mitochondria [ ] or adpr polymers. the latter are formed, e.g., during dna repair by poly (adp-ribose) polymerases (parps). adpr is released from the adpr polymers by glycohydrolases [ , ]. expression of trpm has been demonstrated in several tumor enti- ties such as insulinoma [ ], hepatocellular carcinoma [ ], prostate cancer [ ], lymphoma [ ], leukemia [ ] and lung cancer cell lines [ ]. trpm activity increases the susceptibility to cell death [ ] prob- ably by overloading cells with ca + (fig. a). remarkably, cancer cells may evade trpm -mediated cell death. in lung cancer cells, de-methylation of a gpc island within the trpm gene gives rise to new promoters that regulate transcription of a non- functional truncated trpm channel [ ] and to a trpm specific anti- sense rna. this antisense rna inhibits trpm translation. moreover, the truncated channel is non-functional and acts dominant negative, thus switching off the tumor-suppressing function of the full-length trpm protein [ ] (fig. b). the initially described member of the vanilloid family of trp chan- nels, the nociceptive and heat receptor trpv , is reportedly expressed in several tumor entities such as uveal melanoma [ ], pancreatic [ ] and prostatic neuroendocrine tumors [ ], glioblastoma [ ] and urothelial cancer of human bladder [ ]. at least in the latter two tumor entities, trpv exerts anti-oncogenic effects [ , ]. trpv expression inversely correlates with glioma grading [ ]. remarkably, neural precursor cells have been demonstrated to induce er stress- mediated cell death of glioblastoma cells by activating glioblastoma trpv channels through secretion of endogenous vanilloids [ ]. along those lines is the observation that a trpv antagonist promotes tumorigenesis in mouse skin [ ]. notably, targeting of trpm and trpv by rna interference has been demonstrated to decrease gamma irradiation-induced formation of nuclear γh ax foci and further dna damage response in a lung adenocarcinoma cells [ ]. since γh ax foci are used as a surrogate for dna double strand breaks, one might speculate that trpm or trpv may amplify ionizing radiation-induced insults (fig. ). another interpretation which has been favored by the author of the study [ ] would be that activity of trpm and trpv is required for the formation of dna repair complexes. in combination, the data hint to the possibility of radiosensitizing cancer cells by pharmacologically activating trpm or trpv channels. whether this might become a promising new strat- egy of tumor radiosensitization has to await animal studies. trpm trpm trpm adp-ribose cell death dsb radiation ca + ca +overload er nucleus mito. oxidative stress trpm trpm -te trpm trpm -te trpm te as cpg island adp-ribose trpm -as dsb radiation ca + survival ca + er nucleus mito. survival ba fig. . speculative mechanism of a putative trpm -mediated radiosensitization (a) and reported strategy [ ] of lung cancer cells to avoid trpm -mediated susceptibility to cell death (b), for details see text. trpm -te (te): truncated trpm , trpm -as (as): trpm antisense rna, mito.: mitochondrion). s.m. huber et al. / biochimica et biophysica acta ( ) – . ion channels conferring intrinsic radioresistance dna repair involves cell cycle arrest, chromatin relaxation and for- mation of repair complexes at the site of dna damage. moreover, radiation-induced formation of radicals requires activated radical detoxification pathways and increased oxidative defense to constrain the radiation-induced insults. all these processes of stress response lead to elevated atp consumption which requires intensified energy supply. recent in vitro observations suggest that these processes depend at least partially on radiation-induced ion channel activation. studies of our laboratory indicate that survival of irradiated human leukemia cells critically depends on ca + signaling involving radiogenic activation of trpv / -like nonselective cation and kv . voltage-gated k+ channels [ , ]. the nonselective cation channels in concert with kv . generate radiogenic ca + signals that contribute to g /m cell cycle arrest by camkii-mediated inhibition of the phosphatase cdc b. activity of the latter is required in these cells for release from radiation-induced g /m arrest via dephosphorylation and thereby activation of cdc , a component of the mitosis promoting factor. exper- imental interference with the radiogenic ca + signals, e.g. by pharma- cological inhibition or knock-down of kv . overrides cell cycle arrest resulting in increased apoptosis and decreased clonogenic survival of irradiated leukemia cells [ , ]. this radiosensitization by kv . targeting demonstrates the pivotal role of radiogenic kv . channel activation for cell cycle arrest and dna repair. similar to leukemia cells, a lung adenocarcinoma cells reported- ly respond to ionizing radiation with activation of kv k + channels [ ] and transient hyperpolarization of the plasma membrane. later on, the membrane potential of the irradiated a cells strongly depolar- izes. this depolarization is dependent on external glucose and inhibited by phlorizin, a sodium glucose cotransporter (sglt) blocker. in parallel, irradiation induces phlorizin-sensitive h-glucose uptake within few minutes after irradiation [ ]. combined, these data suggest that radio- genic activation of sglt transporters and kv k + channels cooperate in glucose fuelling of the irradiated a cells, the former by generating the glucose entry routes, the latter by increasing and maintaining the driving force for na+-coupled glucose entry. glucose uptake by sglts is mainly driven by the inwardly directed electrochemical driving force for na+ which in turn is highly dependent on the k+ channel- regulated membrane potential. sglts allow efficient glucose uptake even from a glucose-depleted microenvironment which is typical for malperfused solid tumors [ ]. it is therefore not surprising that several tumor entities such as colorectal, pancreatic, lung, head and neck, pros- tate, kidney, cervical, breast, bladder and prostate cancer as well as chondrosarcomas and leukemia upregulate sglts [ – ]. sglt has been shown to be in complex with the egfr [ , ] and radiogenic sglt activation depends on egfr tyrosine kinase activi- ty [ ]. importantly, radiogenic increase in glucose fuelling seems to be required for cell survival since the sglt inhibitor phlorizin radiosensitizes a lung adenocarcinoma and fadu head and neck squamous carcinoma cells [ ]. intracellular atp concentration has been reported to drop in irra- diated a cells indicative of an irradiation-caused energy crisis. notably, recovery from radiation-induced atp decline is egfr/sglt- dependent and associated with improved dna-repair leading to increased clonogenic cell survival. this is evident from the fact that egfr or sglt blockade delays recovery of intracellular atp concentra- tion and histone modifications necessary for chromatin remodeling during dna repair. vice versa, inhibition of the histone h modification prevents chromatin remodeling as well as energy crisis [ ]. together, these data suggest that irradiation-associated interactions between sglt and egfr result in increased glucose uptake, which counteracts the energy crisis in tumor cells caused by chromatin remodeling required for dna repair (fig. ) [ , ]. besides plasma membrane ion channels, mitochondrial transport pathways have been shown to contribute to cellular stress response. stress-induced upregulation of uncoupling proteins (ucps) conveys hyperpolarization of the membrane potential across the inner mito- chondrial membrane (ΔΨm,) and thereby formation of reactive oxygen species [ ]. ucps are reportedly upregulated in a number of aggressive human tumors (leukemia, breast, colorectal, ovarian, bladder, esopha- gus, testicular, kidney, pancreatic, lung, and prostate cancer) in which they are proposed to contribute to malignant progression (for review see [ ]). in addition to malignant progression, ucps may alter the therapy sensitivity of tumor cells. ucp- expression has been associated with paclitaxel resistance of p wildtype lung cancer, cpt- resistance of colon cancer and gemcitabine resistance of pancreatic adenocarcinoma, lung adenocarcinoma, or bladder carcinoma. accordingly, experimental targeting of ucps has been demonstrated to sensitize tumor cells to chemotherapy in vitro (for review see [ ]). notably, ionizing radiation induces up-regulation of ucp- expres- sion in colon carcinoma cells [ ] and in a radiosensitive subclone of b cell lymphoma [ ], as well as ucp- expression in rat retina [ ]. radioprotection might result from lowering the radiation-induced bur- den of reactive oxygen species. as a matter of fact, multi-resistant subclones of leukemia cells reportedly show higher ucp- protein expression, lower ΔΨm, lower radiation induced formation of reactive oxygen species, and decreased dna damage as compared to their parental sensitive cells [ ]. radiation dsb histone phosphorylation (γ recruitment of repair enzymes oxidative insults na+ glucose sglt energy crisis ↓ phlorizin oxidative defense ↑ egfr p k+ driving force erlotinibcell death radiation radiation dsb histone phosphorylation histone acetylation ba survival dna decondensation energy crisis histone acetylation (γh ax foci) h ax foci) fig. . radiation-caused energy crisis (a) and functional significance of sglt -mediated glucose fueling for dna repair and cell survival (b) of irradiated a lung adenocarcinoma cells (dsb: double strand breaks). s.m. huber et al. / biochimica et biophysica acta ( ) – in summary, these data indicate that ion transports through chan- nels may regulate processes that mediate intrinsic radioresistance. only few laboratories worldwide including ours are working on the radiophysiology of tumor cells. the investigation of ion transports in irradiated cells therefore is at its very beginning and the few data available are mostly phenomenological in nature. the molecular mech- anisms that underlie e.g. radiogenic channel activation are still ill- defined. nevertheless, the data prove functional significance of ion transports and electrosignaling for the survival of irradiated tumor cells and might have translational implications for radiotherapy in the future. . ion channels in acquired radioresistance microenvironmental stress such as hypoxia, interstitial nutrient depletion or low ph has been proposed to switch tumor cells from a “grow” into a “go” phenotype. by migration and tissue invasion “go” tumor cells may evade the locally confined stress burden and resettle in distant and less hostile regions. once resettled, tumor cells may readapt the “grow” phenotype by reentering cell cycling and may establish tumor satellites in more or less close vicinity of the primary focus (for review see [ ]). in accordance with this hypothesis, sublethal ionizing irradiation as applied in single fractions of fractionated radiotherapy has been bk cxcr sdf- k+ camkii volume d h o macrophag vascular da ca + s-nitrosylation hif- α fig. . hypothetical signaling underlying radiogenic hypermigration of glioblastoma cells. sdf- damage of the tumor vasculature and resultant tumor hypoxia has been proposed to induce sdf no in tumor-associated macrophages leading to hif- α stabilization by s-nitrosylation [ ]. f unpublished results). sdf- induces ca + signals through cxcr chemokine receptor that in t possibly invasion, e.g., via calpain-dependent [ ] activation of matrix metalloproteinases [ demonstrated in vitro and/or in rodent tumor models to induce migra- tion, invasion and metastasis or spreading of cervix carcinoma [ ], head and neck squamous cell carcinoma [ ], lung adenocarinoma [ , ], colorectal carcinoma [ ], breast cancer [ – ], meningioma [ ], medulloblastoma [ ] and glioblastoma. in particular, in glioblas- toma the experimental evidence for such radiogenic hypermigration is meanwhile overwhelming [ – ]. glioblastoma cells show a highly migrative phenotype that may “travel” large distances through the brain [ ]. at least in theory, radiogenic hypermigration might, there- fore, contribute to locoregional treatment failure by promoting emigra- tion of tumor cells from the target volume during fractionated radiation therapy. migration and radiogenic hypermigration are well documented in glioma cells. they invade the surrounding brain parenchyma primarily by moving along axon bundles and the vasculature. during brain inva- sion along those tracks cells have to squeeze between very narrow interstitial spaces which requires effective local cell volume decrease and reincrease. glioblastoma cells are capable of losing all unbound cell water [ ]. the electrochemical driving force for this tremendous cell volume decrease is provided by an unusually high cytosolic cl− concentration ( mm) [ , ] which is utilized as an osmolyte. dur- ing local regulatory volume decrease, extrusion of cl− and k+ along their electrochemical gradients involves clc- cl−- channels [ , ], ca +-activated high conductance bk- [ , , ] and intermediate invasion clc- cl- ynamics ionizing radiation es, endothelial cells, no mage, hypoxia, ros matrix metalloproteinases migration actin dynamics is a hif- α target gene and hypoxia is a strong inductor of sdf- expression. ir-caused - expression [ ]. beyond that, ionizing radiation reportedly stimulates the generation of inally, radiation may directly stabilize hif- α as deduced from in vitro experiments (own urn contribute to the programming and mechanics of migration (for details see text) and , ]. cxcr sdf- tgfbr cd + k+ mmp- sdf- “homing“ endothelial cell pericyte v nutrition vegf vegf cd + tgf-ß transition cd - ik cxcr sdf- tgfbr cd +k+ radiation sdf- radiation k+ “niche“perivascular mmp- cxcr ik/bk transition signaling network a b c cd + vegf β α α β fig. . synopsis of the signaling network in glioblastoma conferring radioresistance and speculative role of ionizing radiation herein. a. irradiation induces secretion of sdf- [ , – ] and transition of cd − “differentiated” glioblastoma cells to cd + gscs with up-regulated cxcr [ ], β /α integrins [ ], tgfb receptor [ ], tgf-β responsiveness [ ], and ik ca +-activated k+ channel-dependent highly migratory and invasive phenotype [ ] b. irradiation promotes “homing” of gscs to perivascular niches by stimulating cell migration. c. the reciprocal interaction between glioblastoma and endothelial cells strongly depends on matrix metalloproteinase- (mmp- ) expres- sion by glioblastoma [ ] and sdf- signaling of endothelial cells [ ]. importantly, irradiation induces upregulation of mmp- in glioblastoma cells (b) which is required for tissue invasion [ , , , , ] and vegf secretion (b) [ , ] which reportedly may promote angiogenesis [ ]. in addition, transition of glioblastoma cells into endo- thelial cells [ ] and pericytes [ ] reconstruct the glioblastoma vasculature which sup- ports both, vessel function and tumor growth. s.m. huber et al. / biochimica et biophysica acta ( ) – conductance ik k+ channels [ , ]. inhibition of either of these chan- nels attenuates glioblastoma cell migration or invasion [ , – ] confirming their pivotal function in these processes. ionizing radiation has been demonstrated in our laboratory to acti- vate bk k+ channels in glioblastoma cells in vitro [ ]. radiogenic bk channel activity, in turn, is required for ca +/calmodulin kinase ii (camkii)- [ ] and consecutive camkii-dependent clc- channel acti- vation (own unpublished observation and [ ]). inhibition of bk or camkii abolishes radiogenic hypermigration [ ] indicating bk channel activation as key event of radiogenic hypermigration of glioblastoma cells. radiogenic hypermigration is paralleled by radiogenic expression of the chemokine sdf- (stromal cell-derived factor- , cxcl ) in different tumor entities including glioblastoma [ , – ]. glioblasto- ma cells reportedly express cxcr chemokine receptors and sdf- stimulates glioblastoma cell migration via cxcr -mediated ca + sig- naling [ ]. cxcr receptors reportedly signal through phospholipase c and bk channels have been shown to be functionally coupled with ip receptors in the er [ ] suggesting (and confirmed by own unpub- lished observations) that radiogenic sdf /cxcr signaling is upstream of bk channel activation. sdf- , in turn, is a target gene of the transcrip- tion factor hif- α which reportedly becomes stabilized, e.g. by s- nitrosylation, upon irradiation [ , – ] (fig. ). together, this gives a good example of radiogenic signaling which integrates biochem- ical signaling, electrosignaling (i.e., bk-dependent regulation of mem- brane potential) and ca + signaling modules (more details are given in the legend to fig. ). ionizing radiation has been demonstrated to select stem (cell)-like glioblastoma cells (gscs) or even induce transition of “differentiated” cancer cells to gscs/cscs in glioblastoma [ – ] and other tumor entities [ ]. notably, “stemness” is associated with sdf- secretion [ ] and markedly increased cxcr chemokine expression [ ]. im- portantly, cxcr upregulation is required to maintain “stemness” of non-small cell lung cancer [ ] and glioblastoma cells [ ]. in accor- dance to cxcr upregulation, gscs show a highly migratory/invasive phenotype [ , ]. most importantly, this phenotype is highly dependent on the ca +-activated ik k+ channel [ , ]. furthermore, ik channels have been demonstrated to be overexpressed in about one third of the glioma patients with ik protein expression correlating with poor patient survival [ ]. unexpectedly, a previous report demonstrated that xenografted cd + stem-like subpopulations of glioblastoma exhibit a higher radioresistance than xenografted cd − cells while radiosensitivity of both subpopulations does not differ in vitro [ ]. this clearly indicates a function of the brain microenvironment for radioresistance. in partic- ular, endothelial cells have been postulated to promote glioblastoma therapy resistance [ ]. part of the reported reciprocal interaction between glioblastoma cells and endothelial cells as well as of the com- plex signaling network in perivascular “niches” is schematically sum- marized in fig. . albeit merely speculative, the idea that radiogenic hypermigration might promote “homing” of (cxcr -highly-expressing stem-like) glio- blastoma cells to perivascular niches is highly attractive. the subse- quent reciprocal modifications of glioblastoma and endothelial cells might eventually induce radioresistance of glioblastoma cells. together, these data suggest that radiogenic hypermigration might contribute to the apparently high radioresistance of glioblastoma cells either by pro- moting evasion from the radiation target volume or by stimulating the chemotaxis of glioblastoma cells to “radioprotective” perivascular niches. . concluding remarks the radiation physiology of cancer cells is yet a neglected research field. while the number of reports on ion channel function in neoplastic transformation, malignant progression or metastasis of cancer cells in- creases constantly only little is known about the role of ion channels in radiotherapy. the few data available strongly suggest that ionizing radiation-induced ion channel modifications are a common phenome- non. importantly, these modifications impact on the stress response and survival of irradiated tumor cells. by modulating intracellular ca + signals radiosensitive ion channels may directly crosstalk with the biochemical signaling of the dna damage response. by driving local cell volume changes radiogenic ion channel modifications may promote cell migration and stress evasion of irradiated tumor cells. by stabilizing the membrane potential ionizing radiation-induced k+ channel activity might facilitate na+-coupled glucose uptake providing the energy for dna-repair. finally, mitochondrial channels upregulated s.m. huber et al. / biochimica et biophysica acta ( ) – by ionizing radiation might lower the oxidative insults associated with ionizing radiation. given the aberrant and partly specific ion channel expression of tumor cells, a more profound understanding of the mechanisms underlying radiogenic ion channel modifications might be harnessed in the future to develop new strategies for the radiosensitization of tumors. acknowledgment this work was supported by a grant from the wilhelm-sander- stiftung awarded to sh ( . . ). bs and dk were supported by the dfg international graduate school (tp t sh). references [ ] s.m. huber, oncochannels, cell calcium ( ) – . 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( ) – . http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://www.krebshilfe.de/fileadmin/inhalte/downloads/pdfs/blaue_ratgeber/ _strahlen.pdf http://www.krebshilfe.de/fileadmin/inhalte/downloads/pdfs/blaue_ratgeber/ _strahlen.pdf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://dx.doi.org/ . /j.radonc. . . http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - 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[ ] r. wang, k. chadalavada, j. wilshire, u. kowalik, k.e. hovinga, a. geber, b. fligelman, m. leversha, c. brennan, v. tabar, glioblastoma stem-like cells give rise to tumour endothelium, nature ( ) – . http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf 	role of ion channels in ionizing radiation-�induced cell death 	 . introduction 	 . radiotherapy 	 . radiosensitizing ion channels 	 . ion channels conferring intrinsic radioresistance 	 . ion channels in acquired radioresistance 	 . concluding remarks 	acknowledgment 	references international journal of recent technology and engineering (ijrte) issn: - , volume- , issue- s , july published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi : . /ijrte.b . s abstract--- massive industrialization and population growth have led to a surge in the global demand for energy in recent years. electricity is the new currency and developing countries are in desperate need of insatiable units of electricity. there is so much potential in hydropower which when harnessed efficiently can show a phenomenal way in addressing the energy crisis. the conventional methods of harnessing the hydropower like generating electricity by damming, etc. have many limitations concerning environmental concerns, aquatic ecological imbalance and other issues. the paper is on vortex induced vibrations aquatic clean energy (vivace). it focuses on clean energy, making use of vortex induced vibrations (viv) to generate electricity. this paper describes the design and fabrication process related to energy harvester to harness vivace. cfd simulations done to obtain the feasible values of some important parameters involved in vivace are also discussed. keywords — hydropower, vortex shedding ,vortex induced vibrations (viv), vortex induced vibrations aquatic clean energy (vivace), energy harvester, cfd simulations. i. introduction india, being a growth engine, plays a crucial role in the world energy trends. there has been a unremitting growth in the electricity production in india from financial year (fy) to (figure ). . billion units (bu) of electricity has been produced in fy in india [ ] . the focus of government of india has shifted to clean energy after it ratified the paris agreement [ ] . the government is all set for boosting investment in renewable energy. in an annual ranking of top renewable energy markets conducted by ey, a uk accountancy firm, indian renewable energy sector is the second most attractive renewable energy market in the world. according to india brand equity foundation (ibef), india looks to meet its energy demand on its own, which is revised manuscript received on july , . dr. ashok b c, visvesvaraya technological university department of mechanical engineering vidyavardhaka college of engineering, mysuru, karnataka india. (e-mail: bcashok@vvce.ac.in) akshay b l, visvesvaraya technological university department of mechanical engineering vidyavardhaka college of engineering, mysuru, karnataka india. (e-mail: akshaybl @gmail.com) akshatha h, visvesvaraya technological university department of mechanical engineering, vidyavardhaka college of engineering, mysuru, karnataka india. (e-mail: akshuakshatha @gmail.com) akash d l, visvesvaraya technological university department of mechanical engineering, vidyavardhaka college of engineering, mysuru, karnataka india. (e-mail: akashdlbenakanahalli@gmail.com) bharath yogendra, visvesvaraya technological university department of mechanical engineering, vidyavardhaka college of engineering, mysuru, karnataka india. (e-mail: yogibharath @gmail.com) expected to reach , twh (terawatt hour) by . so renewable energy is set to play an important role. the ramifications of conventional hydropower generation due to damming of water, change in flow of water, construction of roads and setting up of power lines are disastrous to aquatic ecosystem. how can engineers develop an energy harvester without unbalancing the aquatic ecosystem? billions of units of power incessantly flow down rivers and streams, or wash up on shores, just to dissipate. it is also immensely challenging to harness: how can engineers tap this vast, restless resource to create sustainable energy that emulate fossil fuels and is compatible with existing power grids? the answer to above three questions is vortex induced vibrations aquatic clean energy (vivace). energy crisis can be mitigated by utilizing the unused flow energy of water and producing electricity even in small scales. using the principle of vivace, we can produce clean and renewable energy. during this era of depleting energy, we can obtain considerable amount of electricity. by incorporating vivace, areas having flowing water like streams, rivulets, rivers, etc. can extract energy and generate electricity. this paper focuses on design and fabrication of energy harvester using viv, familiarization with the concept of flow around the cylindrical structure and understanding the vibration phenomena of the cylindrical structure. lift force v/s flow time simulation in transient flow is done using cfd. figure : electricity production in india in each financial year (fy) from to . [ ] ii. design methodology ● background study ● principle ● principle parts ● working principle design and fabrication of energy harvester using vivace (vortex induced vibrations aquatic clean energy) ashok b c. akshay b l, akshatha h, akash d l, bharath yogendra  design and fabrication of energy harvester using vivace (vortex induced vibrations aquatic clean energy) published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi : . /ijrte.b . s the design of our project goes as follows: a. background study . regime of flow one of the non-dimensionless numbers that is utilized to illustrate the flow around a smooth circular cylinder is the reynolds number (re). the reynolds number is the ratio of the inertia forces to viscous forces. flow regimes are obtained as the consequence of immense changes of the reynolds number. the changes of the reynolds number necessitate separation flows in the wake region of the cylinder, which are called vortices. separation does not occur at meagre values of re (re < ). when the re is further increased, the separation starts to occur, becomes unstable, and initiates the phenomenon called vortex shedding at certain frequency. [ ] . vortex shedding the phenomenon of vortex shedding (fig . ) occurs when pairs of stable vortices are susceptible to small disturbances and become unstable at re greater than . for these values of re, the boundary layer over the cylinder surface will separate due to the pressure gradient forced by the divergent profile of the flow territory at the backside of the cylinder. vortex shedding manifests at a particular frequency called as vortex shedding frequency (fv). this frequency normalized with the flow velocity (u) and the cylinder diameter (d), can be seen as a function of the reynolds number [ ] . moreover, the normalized vortex- shedding frequency is called strouhal number (st).the relationship between re in x- axis and st in y-axis is seen in figure . . figure . : vortex shedding figure . : graph of reynolds number v/s strouhal number for smooth circular cylinder . drag and lift forces the pressure distribution of the cylinder due to the flow will change periodically due to cyclical change of the vortex shedding, as a result generating a cyclical variation in the force components on the cylinder. cross- flow and in-line directions are the force components. the lift force (fl) is in the cross-flow direction and the drag force (fd) is in the inline direction. the lift force develops when the vortex shedding begins and it varies at the vortex shedding frequency. correspondingly, the drag force also has the oscillating part due to the vortex shedding, additionally as a result of friction and pressure difference, it also has a small force; this part is called the mean drag [ ] . . cross-flow and in-line vibrations of cylindrical structure vibrations of bluff body materialise as the result of cyclical variations in the force components due to the vortex shedding. the vibrations can be divided as cross flow vibrations (fig. . (a)) and in-line vibrations (fig. . (b))). the lift force causes the cross-flow vibration while the drag force causes the in-line. both vibrations are often called the vortex- induced vibrations. figure . (a): sketch of inline vortex induced vibrations [ ] figure . (b): sketch of cross-flow vortex induced vibrations [ ] . vortex induced vibrations (viv) viv result from vortices forming and shedding on the downstream side of a bluff body in a current. vortex shedding alternates from one side to the other, thereby creating an oscillation / a vibration. the viv phenomenon is non-linear. this property of viv has huge implication as it can produce beneficial energy at high efficiency over a wide range of current speeds. . lock-in frequency the vortex shedding frequency (fv) will be trailing the stationary-cylinder strouhal frequency (f) till the reduced velocity (vr) arrives at some value. when the flow speed increases, vortex shedding frequency (fv) does not follow the strouhal frequency (f) and begins to follow the natural international journal of recent technology and engineering (ijrte) issn: - , volume- , issue- s , july published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi : . /ijrte.b . s frequency (fn) of the system. this phenomenon takes place at a range. in this range, the vortex shedding frequency is locked into the natural frequency of the system. this phenomenon is known as the “lock-in’’ phenomenon. at this range, fv, fn and f have the same values, therefore, the lift force oscillates with the cylinder motion resulting in large vibration amplitudes. b. principle: vortex induced vibrations aquatic clean energy (vivace) vortex induced vibration aquatic clean energy (vivace) replicates the features of fish movements. fish curve their bodies to glide between the vortices shed by their bodies in front of them. their muscle power alone cannot propel them forward through the water at the speed they go, so they ride in each other's wake. [ ][ ] vortex induced vibrations are undulations that a rounded or cylinder-shaped object make in a flow of fluid, which can be air or water. the presence of the object puts twirls in the current's speed as it glides by. this causes eddies or vortices which generate a pattern on either sides of the object. the vortices push and pull the object up and down or left and right, perpendicular to the current. vivace works due to the presence of the bluff body in the current causing alternating vortices to form above and below the body. the vortices push and pull the passive body up and down creating mechanical energy i.e. vibrational energy. later, this energy is converted into electricity. because the oscillations of vivace would be slow, it is theorized that the system would not harm marine life like dams and water turbines can. [ ][ ] c. principle parts ● bluff body (cylinder) ● rack ● pinion ● gear ● gear coupled with dc generator d. working principle the figure below shows the working principle of our project. figure . : cad model of experimental set-up figure . : enlarged view of gear coupled with generator the main principle behind this project is the conversion of linear oscillation of cylinder to rotational motion of the pinion. as the cylinder (bluff body) is subjected to hydro- energy, it tends to oscillate due to the vortices formed around the structure of the cylinder, which can be converted to rotational energy to generate electricity. in this configuration, the cylinder is fixed axially and cross flow vortex induced vibrations takes place. a rack and pinion arrangement is used for converting linear motion to rotational motion. as the cylinder reciprocates, the rack’s movement rotates the pinion attached to it. the pinion drives the shaft which in turn rotates the alternator to generate power. thus, electrical energy is obtained by continuous oscillation of the cylinder and dc output voltage is obtained. iii. design specifications a. formulae . reynolds number one of the non-dimensionless hydrodynamic numbers that is used to describe the flow around a smooth circular cylinder is the reynolds number (re). by the definition, the reynolds number is the ratio of the inertia forces to viscous forces and formulated as: = ⁄ in which d is the diameter of the cylinder, u is the flow velocity and v is the kinematic of the fluid. . vortex shedding vortex shedding occurs at a certain frequency, which is called as vortex shedding frequency (fv). this frequency normalized with the flow velocity u and the cylinder diameter d, can be seen as a function of the reynolds number: = ⁄ furthermore, the normalized vortex- shedding frequency is called strouhal number (st) and the empirical formulae is: design and fabrication of energy harvester using vivace (vortex induced vibrations aquatic clean energy) published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi : . /ijrte.b . s = . ( − . ) . lift force lift force is formulated as follows: = sin( + ∅ ) . is the amplitude of the oscillation lift. the vortex shedding is represented by = ⁄f and ∅ is the phase angle between oscillating force and vortex shedding. cl are the dimensionless parameters for lift force and can be calculated using: = . × × where l, d and u are the cylinder length, cylinder diameter and flow velocity respectively. [ ] . apparent mass m = m + m app pipe dis where mpipe= ( × ) + mdis= ρfluid× = ( × ) where vol is volume of the cylinder, mdis is mass of fluid displaced by the cylinder, ρfluid is water density, mass madd represents additional mass added to the pipe, which will initially be set as . the pipe mass mpipe was determined based on unit length density (ρ cyl) of . kg/m. . spring stiffness stiffness is a measure of the resistance offered by an elastic body to deformation. spring stiffness (k) is the force required to cause unit deflection. it is given by: = ( ) × mapp where is vortex shedding frequency and mapp is apparent mass. iv. analytical calculations & results these are the known values: property parameter values cylinder material m pvc cylinder diameter d . mm cylinder length l mm water density kg/m linear cylinder density . kg/m fluid temperature t ⁰ c water kinematic density . − m /s maximum flow speed u m/s calculations: . reynolds number (re): = ⁄ = . × − × ⁄ . − = . . strouhal number (st): = . ( − . )= . ( − . ) . p = . . vortex shedding frequency (fv): = ⁄ = . × ⁄ − . × = . . lift force ( ): = . × × = . × × − × . − × × . = . n coefficient of lift cl is assumed . as a conservative estimate based on background research. realistically, cl varies with displacement of the cylinder, so this value is an average . apparent mass (mapp): = ( × ) = (( . × − ) × ( × − )) = . × − mdis= ρfluid× = × . × − = . kg madd= kg mpipe= ( × ) + mpipe= ( . × × − )+ = . kg mapp = mpipe+ mdis = . kg . spring stiffness (k): k= ( ) × mapp = ( × × . ) × . = . kg/m = . × . k = . n/m v. cfd simulation figure . : cfd simulation of lift v/s flow-time the turbulent analysis is used in the cfd simulation as the reynolds number is in turbulent region. k-omega (due international journal of recent technology and engineering (ijrte) issn: - , volume- , issue- s , july published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi : . /ijrte.b . s to transient flow) type of turbulence model is chosen. in figure . , the displacement history of the freely vibrating cylinder at re = is shown. the simulation is conducted for second flow time. the vertical axis indicate the lift force in newton and the horizontal axis is the flow duration in second. from the figure, it can be seen that the cylinder response rises after a second. between the time value of second to . seconds, the lift force is constantly rising. after . seconds, the lift force is constant and measures around n. vi. conclusion in this paper the viv experiment on the energy harvesting device with a cylinder, rack and pinion and generator was done. through mathematical calculations, cfd modelling and small-scale experiments, the potential for vortex- induced vibrations as an energy source was studied. initial research was conducted on viv theory and existing aquatic energy technologies, including vivace. based on the background research, mathematical calculations were done in order to predict the relationship between experimental parameters and cylinder response. based on the mathematical calculations, cfd modelling was done to obtain few key parameters involved to establish feasibility of small scale viv testing and to create estimates for experimental results. overall, this project demonstrated the power generation at small scale. the output dc voltage obtained lights up the led in our case. therefore, there is a potential for vortex- induced vibrations as a source of energy generation. vii. scope for future work the tests were conducted at low velocity. these speeds are significantly lower than those found in ocean currents and river flow. increasing the reynolds number by increasing fluid velocity and increasing cylinder diameter by a few inches would allow for results that could more accurately predict the potential for the technology under realistic conditions. because of the low velocity for the fluid in the experiment, the lift force of the fluid acting on the cylinders was also small. this lift force could only overcome small amounts of damping and so damping was limited to the damping caused by the fluid. the vibrations of the cylinders subjected to fluid flow can only perform useful work if a system exists to extract the energy. for large scale, where flow speeds are significantly high, piezoelectric material can be used for mast. as load increases on mast, stress will be induced in piezoelectric material thereby producing electricity more efficiently. ac generators can be used in case of high flow speeds. at low flow speeds, ac generators are not feasible as some energy generated will be wasted for the conversion of direct current to alternating current. but when velocity increases, load on mast also increases and use of ac generator is feasible. acknowledgment the authors wish to acknowledge the management of vidyavardhaka college of engineering (vvce) for their consistent encouragement and support for the research activities. the authors are grateful for the support and guidance given by dr. b sadashive gowda, principal, vvce, dr. g.b krishnappa, dean of research and development, vvce and dr. g.v naveen prakash, head of mechanical engineering department, vvce references . “international energy outlook ”, a energy information administration (eia), department of energy, usa. . “renewables ”, international energy agency (iea). . “bp statistical review”, ministry of power, aranca research. . raghavan k et.al "effect of reynolds number on vortex induced vibrations", proceedings of iutam symposium, hamburg, germany, july . . lee j.h et.al “integrated power take off and virtual oscillator system for the vivace converter: vck system identification”, proceedings of the asme international engineering congress and exposition, paper #, imece - , lake buena vista, fl, nov. - , . . foulhoux l et.al "forces and moments on a small body moving in a -d unsteady flow", journal of offshore mechanics and arctic engineering ( ). . kai l et.al “two tandem cylinders with passive turbulence control in fiv: relation of oscillation patterns to frequency response”, proceedings of the th omae conf., paper # , trondheim, norway, june - , . . bernitsas m.m et.al “vivace (vortex induced vibration aquatic clean energy): a new concept in generation of clean and renewable energy from fluid flow”, omae . . bernitsas m.m et.al “the vivace converter: model tests at high damping and reynolds numbers around ”, omae . . raghavan k et.al "effect of bottom boundary on viv for energy harnessing at × < re < . × ”, omae . . john d. anderson jr., “computational fluid dynamics: the basic with applications”, international edition , isbn - - - . . b. mutlu sumer et.al “hydrodynamics around cylindrical structures: advanced series of ocean engineering- volume (revised edition)”, isbn - - - . the kinesio taping method for myofascial pain control review article the kinesio taping method for myofascial pain control wei-ting wu, chang-zern hong, and li-wei chou , , department of physical medicine and rehabilitation, china medical university hospital, taichung , taiwan department of physical therapy, hungkuang university, taichung , taiwan school of chinese medicine, college of chinese medicine, china medical university, taichung , taiwan research center for chinese medicine & acupuncture, china medical university, taichung , taiwan correspondence should be addressed to li-wei chou; chouliwe@gmail.com received march ; revised april ; accepted april academic editor: alan needle copyright © wei-ting wu et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. many people continue suffering from myofascial pain syndrome (mps) defined as a regional pain syndrome characterized by muscle pain caused by myofascial trigger points (mtrps) clinically. muscle spasm and block of blood circulation can be noticed in the taut bands. in the mtrp region, nociceptors can be sensitized by the peripheral inflammatory factors and contracture of fascia can also be induced. traditional treatments of mps include stretching therapy, thermal treatment, electrical stimulation, massage, manipulation, trigger points injection, acupuncture, and medicine. however, the pain syndrome may not be relieved even under multiple therapies. recently, the kinesio taping (kt) method is popularly used in sports injuries, postoperative complications, and various pain problems, but little research is focused on mps with kt method. in this paper, we review the research studies on the application to kt in treating mps and other related issues. it appears that the kt application can elevate the subcutaneous space and then increase the blood circulation and lymph fluid drainage to reduce the chemical factors around the mtrp region. therefore, it is suggested that kt method can be used as a regular treatment or added to the previous treatment for myofascial pain. . introduction . . myofascial pain syndrome (mps). myofascial pain syn- drome, defined as muscle pain due to myofascial trigger points (mtrps) [ ], has been considered to be related to poor postures, neuromusculoskeletal disorders, or systemic diseases [ ]. besides, chronic repetitive minor muscle strain, bursitis, enthesopathy, arthritis, or disc lesion can also induce mps [ ]. clinically, patients with myofascial pain complain about local pain in the muscle, often with referred pain. if the associated pathologic reasons are not well treated, the pain often recurs later [ ]. when performing physical examination, the mtrp in a taut band of skeletal muscle can be palpated and local twitch response can be elicited by snapping of the mtrp [ ]. other symptoms of myofascial pain include range of motion (rom) limitation, sooner exhausting, and referred spasm. . . myofascial trigger point (mtrp). for the diagnosis of mtrp, “spot tenderness,” “taut band,” and “pain recognition” are suggested as the three basic criteria, and “referred pain” and “local twitch responses” are the “signs” for it [ ]. in patients suffering from mps, both latent and active mtrps may be noted, with characters of spontaneous pain sensation or pain in response to the muscle movement in active mtrps and tender without spontaneous pain sensation in latent mtrps. patient with mps begins with one active mtrp, called primary mtrp, in the affected muscle due to reasons mentioned above. when under inappropriate treatment, expanding of pain region and additional active mtrps, called secondary or satellite mtrps, will develop [ ]. . hypothetical mechanism of myofascial pain syndrome . . etiology of myofascial trigger point. acute muscle over- load can activate mtrps. if the lesion is not well controlled, progressive scar tissue will be formed and become a chronic lesion. it may be the major cause of degeneration and activation of mtrp in later life [ ]. hindawi publishing corporation evidence-based complementary and alternative medicine volume , article id , pages http://dx.doi.org/ . / / http://dx.doi.org/ . / / evidence-based complementary and alternative medicine . . integrated hypothesis of mtrp. in the hypothesis of mtrp as energy crisis postulated by simons and travell [ ], they have considered “excessive acetylcholine releasing,” “sarcomere shortening,” and “increasing of sensitizing sub- stances” as the three essential characters for the formation of mtrp [ ]. an mtrp is composed of multiple contraction knots with sarcomeres overcontracture and increased diame- ter of that muscle [ , ]. an mtrp contains multiple sensitive loci suspected as nociceptors and active loci in neuromuscu- lar junctions activated with excessive acetylcholine leakage even under relaxation in the nonendplate zone [ ]. in this condition, the sarcomeres in the endplate zone will contract continually and form the contraction knot in the endplate zone and the taut band in the whole muscle fiber, the pain threshold of nociceptors will be decreased, and the symptoms become severe. when energy crisis occurs, ischemic tissues lack adenosine triphosphate to promote calcium pump in the sarcoplasmic reticulum. it will make the muscle contract continually with regional sarcomere shortening and then blocks the supplements of nutrition and oxygen moreover [ , ]. local ischemia and hypoxia can induce secretion of sensitizing substances to cause pain and release abnormal acetylcholine resulting in a vicious cycle [ ]. . . clinical researches of mtrp. to investigate the pain, research of macdonald [ ] showed that muscles with active mtrps have restricted passive rom. since the tension of involved muscle fibers has been increased even at rest, stretching the muscle beyond limitation can produce severe pain. painful contraction can be also noted when performing test of fixed resistance [ ]. after treating the mtrps and releasing the taut band, the rom can be returned to original status. in surface electromyographic (emg) studies performed by headley [ , ], it was found that muscles with active mtrps beginning fatigue, exhausting sooner, and recovering later than normal muscles. another research using surface emg for endurance test on myofascial pain demonstrated that amplitudes of emg activity increased and mean power frequency decreased with time. and on the more painful side, accelerated fatigability was noted with shorter duration of endurance comparing to the normal side [ ]. in a research with surface emg, it was shown that the muscle containing active mtrps was under status of fatigue, and exhausting the energy earlier than the normal one [ ]. besides, after injection of % lidocaine solution on trigger points of upper trapezius muscle, significant reduction in pain intensity (𝑃< . ) and emg activity (𝑃 < . ) in ipsilateral masseter muscle was noted with confirmation of referred spasm due to myofascial pain [ ]. in consideration of image finding, sikdar et al. apply ultrasound on taut band in the upper trapezius [ ]. they found mtrps as focal, hypoechoic regions and reduced vibration amplitude under vibration sonoelastography. it indicated local changes in tissue echogenicity and appeared with elliptic nodules of size about . ± . cm . chen et al. [ ], through mri study, noted that stiffness of the taut band in patients with myofascial pain was about . kpa and % greater than surrounding tissue. to confirm the theory of energy crisis, shah and his colleagues used micropipettes to determine the ph value and the electrolyte concentration in both active and latent trigger points and also in control points [ , ]. they found significant higher concentration of inflammatory mediators (like bradykinin, substance p, tumor necrosis factor-alpha, interleukin- beta, serotonin, and norepinephrine) and lower ph value in the active or latent mtrps regions than those in the normal points. these inflammatory mediators can induce peripheral sensitization of nociceptors in muscle or central sensitization in central nervous system. when the message was transferred to spinal cord through nociceptors, it can induce neural circuits of mtrp in central nervous system and can form latent mtrps in muscle [ , , ]. when increasing the stimulation to this neural circuit due to acute or chronic injury, latent mtrps can be activated into painful active mtrps. researches conducted by mense [ , ] for central sensitization reported that persistent stimulation of sensory afference from muscles would lead to neuroplastic changes in the posterior horn of the spinal cord and allodynia often associated with active mtrps. releasing of substance p, glutamate, and calcitonin gene-related peptide from the primary afferent fibers can sensitize the nociceptors either at receptive or spinal ends. these neuropeptides will also enter into other synaptic associations with other posterior horn neurons with consequence of hyperalgesia. besides, nociceptors near the site of pathology can transmit messages to neural connections of associated mtrps and then induced the latent mtrps to active mtrps. . treatment of myofascial trigger point due to multiple factors of mps, single management or therapy may not overcome the problem effectively. treat- ments of mtrp include manual therapies [ ], physical therapy modalities [ ], needling therapy (including mtrp injection [ ], dry needling [ – ], acupuncture [ – ], percuta- neous soft tissue release [ ], and subcutaneous needling [ ]), or oral medicine. eliminating any perpetuating factors and introducing adequate education and home programs to patients are also important [ , ]. the earliest effective therapy suggested for treatment is spraying ethyl chloride on skin combined with stretch [ ]. travell suggested applying two or three sweeps of spray before or concurrently while gently stretching the muscle to its full length [ ]. but due to the side effects, such as respiratory tract injury, freezing, and environmental destruction, the spray was displaced with ice rubbing. in exercise therapy, lewit and simons [ ] introduced postisometric relaxation (pir) exercise as a treatment. patients perform isometric contraction on those muscles with – % of full strength. then they make the patient relax the muscle three to ten seconds later, following mild stretch of the same muscle by clinician, and relax again. the circle shall be performed for several times. when combining pir evidence-based complementary and alternative medicine exercise with reflex augmentation of relaxation including respiration and eye movement, the effectiveness will be highly enhanced [ ]. cyriax [ ] developed a deep fraction massage requiring that the finger runs across the long axis of muscle fibers or taut bands at level of mtrps, and it is specific for those located at middle of muscle belly. rolfing method introduced focuses on viscoelasticity of the fascia [ ]. by this manual treatment, firm type of colloid fascia due to mechanical perturbation can be transduced to a more liquid form. the fascia con- tains abundant innervation with mechanoreceptors. fascia releasing technique with stimulation of golgi receptors can lead to changes in the underlying tension of the skeletal muscle. at least, by increasing local proprioception, status of dysfunction will be reduced. recently, few studies researched the therapeutic effect of kinesio taping (kt) method as a new therapy of mps and with hope of self-application for this condition. . kinesio taping (kt) method for myofascial pain syndrome . . background of kt method. the concept of kt originated from the tradition athletic taping. traditional athletic taping, with thick, sticky, and firm material, has been developed since . by restricting the rom through immobilizing and stabilizing joints or muscle, the tape can prevent secondary injury effectively, reduce edema and pain, and completely immobilize the treatment area. kt method was developed from to by dr. kenzo kase, in an intension to provide support for musculoskeletal structure without overimmobilization and the side effect from it. kase commercially introduced the tape for kt in , with elastic, cohesive, lightweight, and ventilation characters. the original purpose was for edema control, soft tissue support, joint protection, and relieving heat produced from active inflammation. advanced purpose was continuing the effect of manual therapy from clinic to home care and activity of daily living. after the application of kt for japanese athletics at the seoul olympics in , this method achieved worldwide concerns and then was introduced to the united states to become popular rapidly. . . characters of kt. the name kinesio for this woven- cotton and elastic tape is originated from the word “kinesi- ology,” since the tape applies over and around muscles for movement control and functional goals. this tape, which is with elastic core wrapped within cotton and capable of stretching up to – %, applies heat-sensitive acrylic adhesive to avoid risk of latex allergy especially used in children. the tape without medicinal properties is water- resistant and can remain on the skin for to days. special design with waved structure can alternate the inputs of proprioception and somatosense. this elastic tape can be performed or cut into special pattern for any alignment of the human body easily. . kt method for pain from mtrps: clinical trials and basic research . . clinical researches of fascia. fascia can be separated into superficial and deep layers under traditional concepts. the superficial layer, composed of loose connective and fat tissue, locates between skin and muscle layer. blood vessels, lymph nodes, nerves, fluid, and gel-like matrix are intersecting in this layer. the superficial layer must be soft enough, and cells like mast or white blood cells can cross over for reason of defense, nutrition, support, hot, and metabolite exhausting. the deep layer, with functions of protection and stabilization, is composed of firm and intimate collagen fiber to separate different muscles, nerves, and organs. multiple myofibroblasts locate near the capillary vessels in fascia and are capable of offering enough contractile force [ ]. these cells will not be affected by norepinephrine, acetylcholine, or angiotensin, while sustained tension going through the tissue, nitric oxide, histamine, and oxytocin will induce longer duration but lower energy contraction [ ]. lower ph level in matrix tends to increase contractility of myofibroblasts and then induces a general stiffness of the fascia [ ]. regarding the new concept of the structure of fascia in recent years, guimberteau et al. [ ] developed the multimi- crovacuolar collagen dynamic absorbing system (mcdas). this is quite different from the traditional concepts of fascia with firm, sticky, dehydrated structure obtained from the anatomy sample. microvascular tube are filled with hydrophilic jelly made of proteoglycoaminoglycans. they are limited but crossing over in hollow fibrils made of collagen and elastin. in order to keep being in balance, structures of microvacuolar can separate, blend, reform, and roll over each other in response to all forces from osmotic pressure, surface tension, weight, and gravity. for this reason, the structure of fascia in the whole body is continual and allows multiple sliding directions to correlate the construction of skin, nerve, vessels, and muscles. because capillaries cross over in fascia, circulation will be involved if the fascia becomes retardant, degenerated, and stiff. since previous researches [ , ] reported higher concentration of inflammatory mediators and lower ph value in the active or latent mtrps regions, recirculation through realignment and decompression of the fascia will help relieve the symptoms. . . basic researches of kt method. main purpose of kt method as in figure is elevating the space under skin and soft tissue, so that the space for movement can be enlarged, the circulation of blood and lymph fluid can be facilitated, and healing rate of tissue can be increased [ ]. to confirm this hypothesis, shim and his colleagues [ ] reported a study with rabbits about wrinkles not only compressing the skin, but also elevating the space. they announced positive effect on opening microvalves due to dynamic pressure variation. since periodic compression and decompression to superficial and deep lymphatics, through expansion and contractile properties of the tape during active movement, the flow and circulation were improved. evidence-based complementary and alternative medicine kinesio tape epidermis dermis blood and lymph vessels muscle lymph fluid bleeding, pressure, and pain before taping after taping figure : these two pictures showed the mechanism of kt application on soft tissue. before taping, the lesion site, such as a taut band or bruise, may contain bleeding, pressure, and lymph fluid accumulation and then cause pain. after taping as shown with blue curve, the space- lifting mechanism will help the drainage of fluid. then the inflammation factors and pressure can be reduced, and the movement of muscle can be improved. to confirm this effect, kase [ ] once researched the influence of taping on blood circulation. the participants were randomly tested through ultrasound under doppler view for radial, superficial temporal, and dorsalis pedis artery before and after taping. it was found that the flow rate was increased immediately after kt. bialoszewski and his colleagues [ ] studied patients treated with ilizarov method for lower limb lengthening and complicated with thigh edema. they were divided into two groups. both groups received days of standard physio- therapy, and additional application of kt was performed in the experimental group. they reported statistically significant decrease in the circumference of thigh and leg in both groups (𝑃 = . , 𝑃 = . , resp.), with more significance in the experimental group than the control group with only standard lymphatic massage. however, they did not provide statistical data for intergroup comparison research. aguilar-ferrándiz and his colleagues [ ] reported an article of treating patients with chronic venous insufficiency for weeks. participants were randomly assigned into an experimental group for standardized kt application or a control group for sham kt treatment. only experimental group showed improvements compared to pretreatment val- ues in swelling (𝑃 < . ), muscle cramps (𝑃 < . ), and pain distribution (𝑃 < . ). intragroup comparisons for the improvement of pain score between baseline and posttreatment were significantly greater in the experimental group than the sham group. but placebo effect should also be taken into consideration because of mild reducing of pain score in control group. kalichman et al. [ ] reported a case suffering from mer- algia paresthetica with symptoms of numbness, paresthesias, and pain in the anterolateral thigh. after using kt method for weeks, symptoms and quality of life were significantly improved. . . mechanism of kt method on lymphatic system. in investigation of lymphatic system, a one-way system below the surface of skin, it depends on negative-pressure pumping to guide the fluid flow from superficial to deep layer. this negative-pressure effect is facilitated by the alternative muscle contraction and relaxation. if interstitial pressure around the lymphatic system is much increasing due to edema, intercellular junction doors will be closed [ ]. by muscle contraction, relaxation, and therapies such as massage or compression garment, pressure in each segment can be changed. the lymph and interstitial fluid can recirculate and decrease the swelling and pain sensation [ , ]. besides, due to the drainage effect of lymph edema, the circulation of lesions can be improved and then accelerates the healing of the tissue. ristow et al. [ ] once researched the application of kinesio tex tape after surgery for mandibular fracture. they announced statistically significant decreasing the incidence of swelling when applying kt during the first days after operation. . . other probable mechanisms of kt method for propri- oception and pain. many articles have reported different conclusions of effects on taping, such as proprioception, placebo effect, warning message, or biomechanics. for exam- ple, treatment with additional kt method over exercise for patellofemoral pain syndrome could provide significantly better hamstring flexibility than the control group (𝑃< . ) [ ]. on the other hand, a research of athletic tapes also showed that increasing cutaneous sensory feedback would improve ankle joint position perception (𝑃 < . ) under non-weight bearing condition [ ]. besides, some researchers reported that kt method would improve the rom of neck [ ] and lower trunk [ ]. for example, osterhues [ ] researched the effect of taping on those who suffered from acute whiplash injury. evidence-based complementary and alternative medicine the study group showed a significantly greater decrease in pain immediately (𝑃 < . ) and also significant increase in rom in all directions. osterhues [ ] treated patients of patella bony dislocation with kt based on the concept of stimulation to mechanical receptors of skin from taping and found that the balance and motor control were better than previous status. when performing the kneeling down or eccentric contraction of leg under-weight bearing, visual analogue scale (vas) was decreased. effect of pain control of kt method may associate with gate control theory [ ]. a𝛽-fiber, afferent fiber from sensory neurons of touch, is bigger in diameter and conduction velocity than those for pain including a𝛿-fiber and c-fiber. by stimulating the afferent receptors with light touch in the skin can activate glial cells in the spinal cord. then transmission of pain will be inhibited at the spinal cord level from transmitting to the cortex. until now, no research can confirm that kt can provide effectiveness via this theory but can depend on literatures of other physical modalities used for reduction of pain [ , ]. other issues such as balance of agonist and antagonist, tendon and ligament protection, decreasing muscle activity of protective contracture, and sensing of movement still require further studies. . . clinical taping for facilitation and inhibition. in researching of facilitation for muscle, rood facilitation including fast brushing, light moving touch, and icing on fascia is reported as a useful method [ ]. on the other hand, the inhibitory pattern is correlated with the golgi tendon organ (gto) located at muscle-tendon junction in the insertion end. these methods include lightly compressing the joints, compressing the muscle-tendon junctions, and keeping tendon in stretched condition [ ]. gto, sensitive to changes in muscle tension, connects to muscle fibers and communicates the muscle spindle status. when in action, gto inhibits its own muscle and excites the antagonist [ ]. the input of stimulation for facilitation and inhibition mentioned above can be achieved through taping. by chang- ing proprioception, biofeedback from correct movement pattern, and training or rehabilitation in high intensity, the target muscle groups and coordination can be improved. then let the patient perform similar suitable movement after removing the tape. kaya et al. [ ] applied kt combined with home exercise program on patients who suffered from shoulder pain due to impingement syndrome. the tapes were applied with “insertion to origin technique” over the supraspinatus, teres minor, and deltoid muscles. significant improvement in pain and disability was noted in the taping group one to two weeks later. in şimşek’s research [ ], for outcomes in subacromial impingement syndrome with kt in addition to exercise therapy comparing to the sham taping, pain during movement in the therapeutic group was significantly lower at the th day (𝑃 < . ) in intergroup comparisons. and night pain, pain with movement, shoulder external rotation muscle strength, and pain-free shoulder abduction rom in the therapeutic group at the th day were significantly improved (𝑃< . ). . . probable mechanism of kt method for mtrps. the concepts mentioned above can be compatible with the hypothesis proposed by kase about the space, movement, and cooling effect of taping. increasing the space of fascia to improve the circulation can remove the heat produced from inflammation. pain sensation can be diminished due to reduction of the pressure on nociceptors. the theory is similar to that of treatment for mps [ , , ]; therefore we hypothesize that kt method can block the vicious circle of energy crisis. figure showed the possible kt mechanism for the relief of myofascial pain. . . researches of kt method for myofascial pain. wang and her colleagues [ ] investigated the effect of kt method for the relief of mps. taping with “insertion to origin technique” was performed on the upper trapezius muscle and statistically significant pain relief was found immediately after the treatment. they considered the effects due to taut band stretching and stimulation of skin receptors. no improvement was reported by the patients in the control group. the improvement of vas in the experimental group remained statistically significant hours later. garćıa-muro et al. [ ] reported a patient with shoulder pain of myofascial origin under intervention of kt method. they found that this patient had significant improvement in the vas, algometry, functional tests, and active rom, resolving the problem in the following days. therefore, they announced that kt methods were appropriate for treating mtrps. . clinical application of kt method: prescription and contraindication kt method combined with other therapeutic interventions may reduce pain, regulate (facilitate or inhibit) muscle func- tion, provide proprioceptive feedback, and stabilize joint. before prescribing kt, the practitioner shall understand the past history, posture at daily living, type of work or exercise, biomechanics and duration of injury, and previous treatments and the effects. detailed physical examination includes inspection, palpation, active and passive rom, resistant test, and identification of the mtrps and taut bands. it is also important to consider the “upper and lower crossed syndrome” announced by janda [ ], such as tightness of upper trapezius and pectoralis combined with weakness of rhomboid and anterior serratus. after history taking, exami- nation, and locating the mtrps, manual therapy or needling (dry needling or injection to mtrps) can be performed as necessary. for relieving the swelling and tenderness after injection, taping can be used following the guidance for the desired direction of drainage. the basic principle of prescription of kt for myofascial pain focuses on the patterns of facilitation and inhibition. when the tape applies on the muscle from its origin to the insertion site, it can provide the effect of facilitation to the muscle contraction [ ]. on the other hand, when taping from insertion to origin, inhibition and relaxation of muscle spasm will be the effect [ ] which is most useful for myofascial pain and muscle spasm. evidence-based complementary and alternative medicine placebo effectimprovement of motor control prevention of further injury or reinjury biofeedbackproprioceptive stimulation ( ) removal of inflammatory substance ( ) removal of inflammatory heat ( ) decrease of pressure on nociceptors immobilization somatosensory stimulation gate control increase of space in soft tissue facilitation of circulation golgi tendon organ stimulation due to mtrps relief of pain figure : the possible mechanism of kinesio taping for the relief of myofascial pain. the contraindication of kt method includes taping on sites of acute infection, open wounds, deep vein thrombosis, malignancy, and severe allergy. djordjevic et al. [ ] sug- gested checking skin for allergy to the tape by applying a small ( × cm ) patch of tape on the volar side of forearm. the positive finding of this allergy test was redness or other skin changes noted in minutes. if patient suffered from diabetes mellitus, taping shall be carefully used due to possible sensory defect. . limitation of researches on kt method researches for the effect of kt method often show different results. hsu and his colleagues [ ] applied taping on baseball players with shoulder impingement and then measured the emg activities of the upper and lower trapezius. they found significant increase of the lower trapezius muscle activity in the arm-lowering phase ( – ∘, 𝑃 < . ) in comparison to the placebo taping. similar research with increasing bio- electrical activity of vastus medialis muscle was reported by słupik et al. [ ]. other researchers such as firth et al. [ ] used the hoffman reflex amplitudes to assess the effect of taping on people with achilles tendinopathy. they reported that the h reflex remained unchanged in the soleus and gastrocnemius in study group. therefore, more research studies are necessary to clarity of the effectiveness of kt method. many limitations in researches shall be overcome, and it is very difficult in building random or double blind trials. furthermore, the taping techniques were variable in previous studies. although all procedures of kt for a similar disorder were performed according to kase’s original concept, different practitioners might perform different technique based on their previous experience and manner and could induce the bias [ ]. another limitation for research is the placebo effect. some research announced that visual input of different color and the sensation stuck on skin may make the positive expectancy [ ] and may make the patients feel confidence, stability, and reassurance [ ]. besides, no suitable machine or image data can confirm the effect of taping at anytime and anywhere. with the functional improvement of ultrasound, certain landmark could be tracked more easily. by using sonography, we can exactly define the depth, certain muscle, and surrounding tissue and note the twitch response during injection. we can not only avoid injury from treatment but also increase the specificity of the target tissue for taping. for example, in cases with epicondylalgia after kt method application, liu and his colleagues [ ] reported improvement of epicondylar muscles sliding in ultrasonic image when wrist was moving. since the flexibility of tissue correlates with the pathologic status, sonoelastography can be used for identifying the location and may be considered for researching of outcomes after taping. . conclusion in clinical practices, kt method was applied in sports injuries, postoperative complications, various pain problems, and many other conditions. the tape is simple to carry out, economic, and less traumatic. in treatment of patient with mps who cannot be rehabilitated regularly, some researchers suggested taping through self-application as a new therapy [ ]. however, self-application of tape may be difficult in some aspects including the limited knowledge in anatomy or biomechanics, the inadequate knowledge in trigger point examination, the lack of experience of taping method, the requirement of using both hands, and the location of evidence-based complementary and alternative medicine the mtrp (such as rhomboid muscle). therefore, most people cannot tape by themselves. in order to obtain a better effect, it is also necessary to combine therapeutic exercise, postural changing, and adjustment of daily living. finally, we considered that kt method could be applied as another choice of mtrp therapy but could need more researches to confirm the effectiveness. conflict of interests financial disclosure statements have been obtained, and no conflict of interests has been reported by the authors or by any individuals in control of the content of this paper. authors’ contribution chang-zern hong had made the same effort as wei-ting wu. acknowledgments this study was supported in part by taiwan ministry of health and welfare clinical trial and research center of excellence (mohw -tdu-b- - ) and by china medical university (cmu) under the aim for top university plan of the ministry of education, taiwan. references [ ] j. g. travell and d. g. simons, myofascial pain and dysfunction: the trigger point manual, vol. , lippincott williams & wilkins, baltimore, md, usa, . 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[ ] y. h. liu, s. m. chen, c. y. lin, c. i. huang, and y. n. sun, “motion tracking on elbow tissue from ultrasonic image sequence for patients with lateral epicondylitis,” in proceedings of the annual international conference of the ieee engineering in medicine and biology society (embc ’ ), vol. , pp. – , ieee service center, august . journal of cancer , vol. http://www.jcancer.org jjoouurrnnaall ooff ccaanncceerr ; ( ): - . doi: . /jca. research paper oxidized vitamin c (dha) overcomes resistance to egfr-targeted therapy of lung cancer through disturbing energy homeostasis mingtong ye #, nengzhi pang #, ting wan , yuanling huang , tianyi wei , xuye jiang , yujia zhou , yufeng huang , hainan yang , zhenfeng zhang , lili yang  . department of nutrition, guangdong provincial key laboratory of food, nutrition and health, school of public health, sun yat-sen university, guangzhou, guangdong, pr china. . department of radiology, the second affiliated hospital of guangzhou medical university, guangzhou, guangdong, pr china. . the first women and children’s hospital of huizhou, huizhou, guangdong, pr china. . huizhou first people’s hospital, huizhou, guangdong, pr china. #these authors contribute equally to this work.  corresponding authors: zhenfeng zhang, changgang rd east, guangzhou, , china; e-mail: zhangzhf@gzhmu.edu.cn; and lili yang, zhongshan road , guangzhou, guangdong, pr china; e-mail: yangll @mail.sysu.edu.cn. © ivyspring international publisher. this is an open access article distributed under the terms of the creative commons attribution (cc by-nc) license (https://creativecommons.org/licenses/by-nc/ . /). see http://ivyspring.com/terms for full terms and conditions. received: . . ; accepted: . . ; published: . . abstract switching aerobic respiration to anaerobic glycolysis of cancer cells plays an important role in development and progression of acquired resistance. since vitamin c enabled the inhibition of glycolysis of cancer cells, and erlotinib-resistant sub-line of hcc (er cells) switched its metabolic features to higher glycolysis for survival, we hypothesize that vitamin c is able to inhibit glycolysis of er cells. in this study, we found that both reduced vitamin c and oxidized vitamin c (dha) could selectively suppress the viability of er cells. dha was efficient in inhibiting glycolysis and leading to energy crisis, which could be one mechanism for overcoming drug resistance to erlotinib of er cells. our data suggest that applying dha could be a novel treatment strategy for nsclc with acquired resistance to targeted therapy. key words: drug resistance; oxidized vitamin c (dha); energy homeostasis; glycolysis. . introduction it has been well established that the first-line tyrosine kinase inhibitors (tkis) which target epidermal growth factor receptor (egfr) mutations in advanced non-small cell lung cancer (nsclc) patients show better response than those patients treated with general chemotherapy [ - ]. nevertheless, acquired resistance often occurs after months tkis treatment on average [ , ]. a major acquired resistant mechanism of nsclc is molecular abnormalities, including egfr-t m mutation, axl or met over-expressions [ - ]. metabolism adaption of cancer, for example, the warburg effect, has appealed great attention in drug resistance during tumor therapy [ ]. reprogramming of glycolytic activity and its corresponding changes of metabolites had been found in drug resistant cells and tissues of breast cancer, breast cancer-associated fibroblasts, human glioblastoma, pancreatic adenocarcinoma, gastric cancer, myeloid leukemia and non-small cell lung cancer [ - ]. targeting metabolite changes and its corresponding metabolic pathways has been novel ways to overcome drug resistance [ ]. data had proven that inhibition of glut activity and expression can sensitize head and neck cancer cells (cal cells) to cisplatin treatment in both normoxic and hypoxic conditions [ ]. another data had shown that development of tamoxifen resistance may be driven by hif- α hyper-activation via modulation of akt/mtor and/or ampk signaling pathways, and that inhibition of aerobic glycolysis and repression of ivyspring international publisher journal of cancer , vol. http://www.jcancer.org this signaling pathway enable the restoration of tamoxifen sensitivity in antiestrogen-resistant breast cancer cells [ ]. similar outcomes that inhibiting glycolysis with -deoxyglucose and -bromopyruvate propylester is able to reverse the drug resistance were also reported in oxaliplatin-resistant colon cancer cells, sorafenib-resistant hcc cells and leukemia cells [ - ]. vitamin c or ascorbic acid had been proposed as an anticancer agent that enables to reduce cancer incidence and cancer treatment-related side effects [ ]. data showed that vitamin c selectively kills kras and braf mutant colorectal cancer cells by targeting gapdh due to increased uptake of oxidized vitamin c, dehydroascorbate (dha), via the glucose transporter-glut , which induces oxidative stress and suppresses gapdh [ ]. other data also showed that vitamin c treatment generates reactive oxygen species (ros) resulting in cell death in multiple myeloma tumor cells, cholangiocarcinoma cells, breast cancer cells and malignant melanoma cells [ - ]. moreover, vitamin c treatment was dose-independent and transporter-independent, such as sodium-dependent vitamin c transporter (svct- ) [ , , ]. in vivo xenograft experiment and case-control study had proven that vitamin c treatment is able to inhibit tumor growth and dietary intake of vitamin c protects against cancer [ , , ]. a recent report found that vitamin c treatment mimics tet restoration to block leukemia progression and vitamin c treatment in leukemia cells enhances their sensitivity to parp inhibition [ ]. we have successfully established a series of erlotinib-resistant subclonal cells (er - ) originated from hcc cells through de-sensitizing the hcc cells in gradually increasing erlotinib concentrations until μm in the culture media and reported axl kinase as a novel resistance molecule in er - cells [ , ]. we also found that er cells switch their metabolic features to higher glycolysis for survival and combining inhibitions of glycolysis and akt/autophagy could overcome drug resistance in er cells [ ]. in this study, we explored the effects of reduced vitamin c and dha on er cells comparing to hcc cells, investigated the underlying mechanism of vitamin c to er cells and hcc cells, and evaluated the potential application of reduced or oxidized vitamin c for a potential adjuvant treatment of nsclc with egfr mutations. . materials and methods . reagents & materials reduced vitamin c (a - g), nevirapine (n ), glucose, nad+, atp, adp and amp were purchased from aladdin chemicals (shanghai, china). oxidized vitamin c ( - mg), pms (p ) were purchased from sigma-aldrich (shanghai, china). mts reagent powder (g ) was purchased from promega corportion (wi, usa). the antibody of gapdh was purchased from abcam (shanghai, china). the antibody of goat anti-rabbit was purchased from santa cruz biotechnology (santa cruz, ca, usa). the antibodies of phosphorlation-ampk and ampk were purchased from cell signaling technologies (beverly, ma, usa). the antibodies of hk- , pk-m and pfk were purchased from proteintech (wuhan, china). rpmi- ( ) was purchased from gibco thermo fisher scientific (guangzhou, china). gsh/gssg test kit was purchased from beyotime biotechnology (shanghai, china). hplc acetonitrile and hplc methanol were purchased from oceanpak (goteborg, sweden). deionized water was purchased from watsons (guangzhou, china). seahorse xf cell culture microplate, xf extracellular flux assay kit, base medium, calibrate medium were purchased from seahorse agilent technologies (beijing, china). . cell culture all cell lines were maintained in rpmi- medium supplemented with % fetal bovine serum and % penicillin & streptomycin in incubator under ℃, % carbon dioxide condition. . cell viability assay cells were transformed to a -well plate in microliter full medium. when cells reached % confluence, flash medium or medium supplemented with reduced vitamin c or dha replaced original medium. mts-pms mixed solution was added and incubated in incubator under ℃, % carbon dioxide condition. absorbance was measured following the instructions of the assay kit (ye, m., et al. ). . protein expression assays protein was isolated from cells using ripa with μm pmsf. lysates were standardized for protein content. the following procedure followed by the guideline of manufacturer. the immune-reactive proteins were visualized using ecl (thermo fisher scientific). . extracellular flux analysis (ocr and ecar) cells were transferred into xf assay well then pretreated with or without dha in normal medium. finally, replacing and washing the normal medium with seahorse assay medium without glucose. ocr and ecar analysis followed the instructions of seahorse analyzer as reported previously (ye, m., et al. ). journal of cancer , vol. http://www.jcancer.org . gsh and gssg measurement cells were cultured in -well plate. when % confluence was reached, cells were treated with dha. then cells were washed for three times with pbs and collected cells after trypsinization. the following procedure followed by the guideline of manufacturer. . metabolites measurement applied by uplc-tof cells were cultured in -well plate. when cells had reached % confluence, adding dha into medium and collecting metabolites after hours. the whole metabolites test procedure was reported previously (ye, m., et al. ). . statistical analysis. mean values and sd were calculated by graphpad prism software. the analysis of variance (anova) was used to identify statistical differences between experimental factors using spss . . p< . was considered as statistically significant. . results . reduced vitamin c decreases viability of er cells in both normal and glucose free condition er cells have higher glycolysis than their parental cells hcc [ ]. we wondered whether some key kinases of glycolysis such as hk- , pk-m are overexpressed. unfortunately, the expression of both hk- and pk-m did not increase in er cells compared to hcc cells (figure a). the expression of pfk , another key kinase of glycolysis was not detected in both er cells and hcc cells (data not shown). when treated with reduced vitamin c for hours, cell viability of er cells and hcc cells was not impacted in the normal glucose medium (figure b). when treated with reduced vitamin c for hours, cell viability of er cells was depressed in mm dosage, while this same treatment was not able to inhibit viability of hcc cells (figure c). we had reported that er cells are more addicted to glucose previously [ ]. when treated with reduced vitamin c after glucose deprivation for and hours, the viability of er cells was suppressed in mm dosage treatment, while this same dosage treatment was not able to affect the viability of hcc cells (figure d, e). this indicates that reduced vitamin c enables to suppress er cells selectively in both normal and glucose free medium. . dha decreases viability of er cells more effectively than reduced vitamin c in normal glucose medium, and dha decreases viability of both er cells and hcc cells in glucose free condition when treated with mm dha for and hours, the viability of er cells was depressed, while the viability of hcc cells was not inhibited in the normal glucose medium (figure a, b). figure . reduced vitamin c decreases viability of er cells in both normal and glucose free condition. a. protein expressions of hk- and pk-m of er and hcc cells analyzed by western blot; b&c. viability analysis of er and hcc cells with supplement of reduced vitamin c for hrs (b) and hrs (c) in normal glucose medium. ** represents p< . comparing to er control group; d&e. viability analysis of er and hcc cells with reduced vitamin c and glucose starvation for hrs (d) and hrs (e). ** represents p< . comparing to er control group. journal of cancer , vol. http://www.jcancer.org figure . dha decreases viability of er cells more effectively than reduced vitamin c in normal glucose medium, and dha decreases viability of both er cells and hcc cells in glucose free condition. a&b. viability analysis of er and hcc cells with supplement of dha for hrs (a) and hrs (b) in normal glucose medium. ** represents p< . comparing to er control group; c. viability analysis of er and hcc cells with dha and glucose starvation for hrs. ** represents p< . comparing to control group; d. western blot analysis of protein levels of p-ampk and t-ampk after hrs treatment with glucose deprivation and/or dha in both er and hcc cells. when cells were treated with mm dha in glucose free medium for hours, the viabilities of both er cells and hcc cells were suppressed (figure c). previously, we had reported that glucose deprivation is able to increase the phosphorylation of ampk [ ]. we wondered whether dha treatment could affect the activation of ampk. we found that dha treatment was able to depress the activation of ampk, especially after glucose deprivation in er cells, while the depression of ampk phosphorylation was only significant in glucose deprivation groups in hcc cells (figure d). these data revealed that at the dosage of mm dha decreased the viability of er cells selectively in normal glucose condition, while decreased the viability of both er and hcc cells in glucose free medium. this phenomenon is closely related to the decrease of ampk phosphorylation under both conditions, which might imply inhibition of further self-protection mechanisms by dha, such as energy balance or autophagy etc. clinically, it is difficult to deprive cells of glucose, so the selective depression of cell viability of er cells by dha with the presence of glucose is more valuable, which is a key focus of our following mechanism study. . dha treatment interrupts the intracellular energy balance of er cells and hcc cells when treated with mm dha for hours, the abundance of nad+ was decreased both in er cells and hcc cells comparing with control group (figure a). importantly, we found the dramatically decreased atp abundance in er cells in mm dha treatment group, while relatively higher abundance of amp and adp levels compared to hcc cells under the same treatment (figure b-d). when the ratio of amp/atp was calculated, we found significant increase of the ratio of amp/atp in er cells compared to hcc cells in mm dha treatment group (figure e). in addition, the ratio of amp/atp was also much higher in mm dha treatment group compared to control group in er cells. this data showed the significant energy disturbance in er cells when mm dha was applied. . dha treatment does not affect oxidative stress status in er cells and hcc cells intracellular dha was not able to be detected in control group without dha addition into the culture medium, while mm dha supplement indeed enabled to increase intracellular dha abundance. the concentration of intracellular dha was higher in er cells than that in hcc cells (figure a). oxidative stress status in er cells and hcc cells was not capable to be disturbed when they were treated with dha in mm or mm dosage for hours (figure b, c). this indicates that dha treatment might not affect intracellular redox status in er and hcc cells. journal of cancer , vol. http://www.jcancer.org figure . dha treatment interrupts the intracellular energy balance of er cells and hcc cells. intracellular abundance of nad+ (a), atp (b), amp (c), amp (d) and amp/atp (e) in er and hcc cells supplemented with mm dha for hrs. ** represents p< . comparing to corresponding control group; && represents p< . comparing to corresponding er group. figure . dha treatment does not affect oxidative stress status in er cells and hcc cells. a. intracellular dha abundance supplemented with dha for hrs, ** represents p< . comparing to corresponding hcc group; && represents dha was non-detected in control group; b. total of intracellular gsh and gssg, control group was set as % in both er cells and hcc cells; c. intracellular gssg abundance, control group was set as % in both er cells and hcc cells. . dha treatment depresses glycolysis of er cells and hcc cells when pretreated with mm dha for hours then replaced it with medium without glucose and dha, glycolysis of er cells and hcc cells was depressed after adding mm glucose (figure a, b). then, we expected to see whether supplement of dha can affect glycolysis of er cells and hcc cells with mm glucose. fortunately, glycolysis of er cells and hcc cells was also depressed immediately by mm dha in mm glucose medium (figure c). after that, we further explored whether pretreatment of cells with dha for hours and then supplement of dha after adding mm glucose could depress glycolysis of er cells and hcc cells. unfortunately, reinforcement effect did not exist (figure d). it indicates that dha depresses glycolysis of both er cells and hcc cells. journal of cancer , vol. http://www.jcancer.org figure . dha treatment depresses glycolysis of er cells and hcc cells. a-d. er and hcc cells were plated on seahorse plate, and cultured for hrs. extracellular acidification rate analysis (ecar) was performed according to the instructions of the manufacturer; a. extracellular acidification rate analysis (ecar) of hcc cells pretreated with mm dha for hrs, ** represents p< . comparing to corresponding base group; ## represents p< . comparing to corresponding glucose group; base group (glucose-free); glucose group ( mm glucose); b. ecar of er cells pretreated with mm dha for hrs, ** represents p< . comparing to corresponding glucose group, ns represents p＞ . comparing to corresponding base group; c. ecar of er and hcc cells supplemented with mm dha in mm glucose; ** represents p< . comparing to corresponding er glucose group; ## represents p< . comparing to corresponding hcc glucose group; d. ecar of er and hcc cells pretreated with mm dha for hrs, then extra mm dha was added in mm glucose, ** represents p< . comparing to corresponding er dha glucose group; ## represents p< . comparing to corresponding hcc dha glucose group. . discussion the fact that cancer cells increase glycolysis rather than oxidative phosphorylation to meet energy requirements under physiological oxygen conditions had been reported to have strong correlation with drug resistance [ ]. recently, we reported that er cells have higher glycolysis potential and overexpress glut and mct , which are more sensitive to glucose deprivation. deficiency of energy under glucose deprivation is one cause of decreased viability of er cells [ ]. however, clinical deprivation of glucose only to cancer cells is not practical, other intervention methods have to be considered. one study indicated that reduced vitamin c selectively kills kras and braf mutant colorectal cancer cells by targeting gapdh, which is due to increased uptake of the oxidized vitamin c via glut [ ]. a recent article showed that pharmacologically-dosed vitamin c enables to selectively kill multiple myeloma tumor cells [ ]. high level vitamin c was reported to be able to be autoxidized, which provides an electron to oxygen to generate h o , thus excessive intracellular h o leads to death of breast cancer cells [ ]. to have better understanding of the effects of vitamin c on er cells and hcc cells, we applied reduced vitamin c on er cells and hcc cells and found that treating cells with mm reduced vitamin c for hours was able to decrease the viability of er cells in the presence of g/l glucose. since er cells are more sensitive to glucose deprivation, as mentioned above, lower concentration ( mm) and shorter incubation time ( hrs) of reduced vitamin c could selectively decrease viability of er cells under glucose starvation condition. it is consistent to the report that high-dose vitamin c treatment selectively induces death of glycolysis-addicted kras and braf driven cancer cells [ ]. other article showed that doxycycline combined with vitamin c is a way to eradicate doxycycline-resistant cancer stem cells (cscs) population [ ]. vitamin c uptake is mediated by two families of transport proteins, including sodium-dependent vitamin c transporters (svcts) and , and the glucose transporters (gluts). gluts, mainly glut and glut , transport the dha, into cells and svcts transport reduced vitamin c directly into the cell [ , ]. considering that er cells overexpress glut , we wondered whether dha treatment would be more efficient to suppress er cells than hcc cells. we found that treatment with mm dha for and hours selectively decreased the viability of er cells in normal glucose level, and mm dha combined with glucose deprivation treatment for hours enabled to suppress both er cells and hcc cells. consistent to the reports that overexpression of glut enables to transport dha more efficiently into cells [ , ], we did find that er cells have higher intracellular dha concentration after dha journal of cancer , vol. http://www.jcancer.org treatment than hcc cells. it indicates that overexpression of glut in er cells facilitates er cells to transport more dha than hcc cells, which is the underlying mechanism of the selective suppression of reduced vitamin c and dha on er cells. studies had shown that vitamin c treatment kills cancer cells is ascribed to the cause of energy crisis due to glycolysis inhibition [ , , , ]. we have recently proven that glucose deprivation enables to cause energy crisis and selectively depress the viability of er cells [ ]. hence we hypothesized that dha treatment is able to reduce energy production. we found that treatment with mm dha for hours enabled to decrease intracellular abundance of nad+ in both er cells and hcc cells. and we also found the dramatically decreased atp abundance in er cells in mm dha treatment, while relatively higher abundance of amp and adp levels compared to hcc cells under the same treatment. it is consistent to the results of these metabolite levels under glucose deprivation treatment as we reported before [ ]. we also found that dha treatment suppressed ampk both in normal glucose and glucose deprivation, which is in accordance with the previous finding [ , ]. we have found that glucose deprivation stimulates ampk and increases autophagy [ ]. ampk protects tumor cells from metabolic crisis through different mechanisms: autophagy induction, maintaining proper atp levels [ , ]. hence, it suggests that dha might depress the viability of er cells through disturbing intracellular energy equilibrium and inhibiting ampk phosphorylation. studies had shown that metformin targets cancer stem cells in breast cancer, pancreatic cancer, glioblastoma and colon cancer by inhibiting oxidative phosphorylation and by reducing mitochondrial atp production resulting in energy crisis [ ]. another research showed that neoalbaconol, a novel small-molecular compound isolated from the fungus, induces energy depletion by reducing the consumption of glucose and atp generation [ ]. it indicates that disturbance of energy balance by suppressing atp production of er cells is the underlying mechanism of viability depression of er cells by dha. to better understand the underlying suppression mechanism of dha to er cells, we applied xf extracellular flux analyzer (seahorse biosciences agilent technologies) to measure real time glycolysis ability, and found that dha pretreatment, dha supplement and combined dha pretreatment with dha supplement were able to suppress glycolysis in er cells and hcc cells. what we found is consistent with previous reports [ , , , ]. studies had shown that increased dha uptake causes oxidative stress as intracellular dha is reduced to vitamin c, which depletes glutathione [ - ]. unfortunately, we did not find dha treatment impacted redox state of er cells and hcc cells. we had previously reported that the antioxidation ability of er cells is destroyed and produces more ros than hcc cells without any treatments ascribed to mitochondria dysfunction [ ]. a paper showed that treatment of cells with vitamin c and quercetin did not modulate cellular reduced glutamine levels in breast cancer cells [ ]. it suggests that dha treatment disrupts energy production of er cells by inhibiting glycolysis directly rather than promoting oxidative stress in the way of consuming reduced glutathione. in conclusion, dha is more efficient than reduced vitamin c in depressing the viability of er cells in the presence of glucose. inhibiting glycolysis which results in energy crisis might be a mechanism of the suppression of the viability of er cells by dha. dha supplement could be a potential strategy against acquired resistance to tkis in nsclcs’ targeted therapies. acknowledgements this work was supported by the national natural science foundation of china (no. and to lili yang; no. and to zhenfeng zhang, to hainan yang); guangzhou science and technology program ( ) to zhenfeng zhang. abbreviations tkis: tyrosine kinase inhibitors; nsclcs: non–small cell lung cancers; dha: oxidized vitamin c or dehydroascorbate; glut: glucose transporter; ecar: extracellular acidification rate; ocr: oxygen consumption rate; gsh: glutathione; gssg: oxidized glutathione; ampk: adenosine ’-monophosphate (amp)-activated protein kinase; p-ampk: phosphorylated ampk; hk- : hexokinase ; pk-m : pyruvate kinase m ; pfk : pyrophosphate- dependent phosphofructokinase ; nad+: nicotinamide adenine dinucleotide. competing interests the authors have declared that no competing interest exists. references [ ] mok ts, wu y-l, thongprasert s, yang c-h, chu d-t, saijo n, et al. gefitinib or carboplatin–paclitaxel in pulmonary adenocarcinoma. n engl j med ; : – . 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[ ] mostafavi-pour z, ramezani f, keshavarzi f, samadi n. the role of quercetin and vitamin c in nrf -dependent oxidative stress production in breast cancer cells. oncol lett ; : – . microsoft word - characterization of solar cell v .docx     nanocrystalline solar cell materials characterization o. e. dyck,* g. perkins,** j. curnes,* p.e. russell,* d. n. leonard* *dept. of physics & astronomy, appalachian state university, boone, nc **dept. of chemistry, appalachian state university, boone, nc with today’s escalating energy crisis there is an increasing demand for renewable resources like solar power. an alternative to the silicon solar cell, that is cheap to make and requires less exotic materials (e.g. raspberry juice and tio nanoparticles), has been reported in the literature[ , ]. we have constructed nanocrystalline solar cells[ ], as pictured in fig. , as part of a nsf step undergraduate science academy project and begun to study the materials that are required for construction in an attempt to improve efficiency of the device. the nanocrystalline solar cell being studied produces current after incoming photons knock electrons off the photo-sensitive dye molecules, which in this study was raspberry juice. this generates a slight electron flow onto the tin oxide coated glass, which is the electrode that carries the electric current produced by the device. current is boosted by increasing the surface area where light interacts with the photosensitive dye. this increase in surface area was achieved by applying a thin coating of titanium dioxide nanoparticles to the tin oxide surface. we investigated the tio particle size and electrode surfaces to determine if improvements in construction methods or materials could be made to gain device performance. characterization of tin oxide coated glass, tio , and conductive carbon layer used in the solar cell was performed by scanning electron microscopy (sem) and atomic force microscopy (afm). this initial analysis was used to establish a better understanding of rms roughness of the electrode surfaces and tio nanoparticle size distribution. a veeco dimension nanomanv afm, operated in tapping mode, was used to acquire several micro-scale scan areas of the solar cell electrode surfaces. as shown in the d rendering of the afm height image of figure , the tin oxide electrode surface was found to have an average rms roughness of ~ nm before a conductive carbon coating was applied. to document the tio nanoparticle size distribution and morphology a hitachi s field emission sem (fesem), operated at kv, was employed to acquire secondary electron (se) micrographs of the tio powder. figures a and b show a low and high magnification micrograph of representative tio nanoparticles morphologies. the micrographs revealed the nanoparticles were agglomerated into larger micron sized particles which may contribute to a reduction in the solar cell performance. the materials characterization data was used to determine which materials in the construction of the nanocrystalline solar cell needed to be modified to produce a more efficient device. from the data acquired to date we have chosen to experiment further with different conductive carbon deposition techniques (e.g. evaporation) and to further process the tio powder for a finer final particle size. references [ ] b. o’regan and m. grätzel, nature, ( ) . [ ] m. grätzel, prog. photovolt. res. appl., ( ) . [ ] http://mrsec.wisc.edu/edetc/nanolab/tio /index.html microsc microanal (suppl ), copyright microscopy society of america doi: . /s https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s https://www.cambridge.org/core https://www.cambridge.org/core/terms     fig. . as constructed nanocrystalline solar cell attached to leads for testing. fig. . d rendering of afm height data acquired from a tin oxide electrode surface. fig. . a. the lower magnification micrograph of the tio nanoparticles shows a large distribution of micron scale agglomerates. b. at higher magnifications individual tio nanoparticles were observed in the larger agglomerates. to improve output of the nanocrystalline solar cell further processing of the tio powder will be needed to reduce particle sizes. a b microsc microanal (suppl ), https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s https://www.cambridge.org/core https://www.cambridge.org/core/terms microsoft word - p _final.doc proceedings: building simulation - - methodology for optimizing the operation of heating/cooling plants with multi-heat source equipments using simulation fulin wang *, harunori yoshida , eikichi ono and hirotake shingu department of urban and environmental engineering, kyoto university, kyoto - , japan * fuwang@archi.kyoto-u.ac.jp, + - - - abstract a methodology for optimizing the operation of heating/cooling plants with multi-heat source equipments is proposed. the methodology decides the optimal combination of the running of multiple heat source equipments to minimize the energy consumption of a heating/cooling plant. the optimal running combination is decided automatically using matlab® stateflow® tool corresponding to cooling and heating loads. the energy consumption at different running combination is simulated using matlab® simulink® tool. a case study is introduced to demonstrate the methodology. an actual district heating/cooling plant located in osaka japan, which consist of two absorption chiller/heaters, one centrifugal chiller, one ice chiller, and two air-source heat pumps, is studied to find the optimal operation combination of the heat source equipments,. the optimal running combination found by this method can reduce primary energy consumption by . %, running cost by . %, and carbon dioxide emission by . %, compared to present operation. keywords optimization, energy consumption, running cost, heating/cooling plant, running combination introduction energy and environment are the most important issues in this new century. the comprehensive study on energy efficiency started since the energy crisis caused by the middle east war in to . the urgent need for oil security management and energy policy co-operation led to the establishment of international energy agency (iea) (scott ). in the field of building energy conservation, the idea that commissioning is a viable method to help ensure good performance of buildings and their energy conservation measures (ecm) was gradually conceived since , because some analyses on the data from the buildings participating in the energy conservation program revealed that many of the installed energy efficiency measures were not performing as expected (bonneville power administration, ). building commissioning is the process of ensuring that systems are designed, installed, functionally tested, and capable of being operated and maintained to perform in conformity with the design intent (ashrae, ). the concept of commissioning is being gradually refined since its birth. now commissioning is not only to verify whether building systems are in conformity with design intent, but also to verify and improve the design itself. especially during operational phase, one of the main commissioning jobs is to optimize the operation of building systems. the optimization of heating/cooling plant, which is the heart and main energy consuming part, is considered to be so important that many researches have been conducted on the operation of heating/cooling plants. celuch ( ) analyzed the issues of energy efficiency, cost, and operation on upgrading an actual central chiller water plant. modeling of an actual cooling plant is also studied and the model is used for simulation and fault detection during the commissioning for a heating/cooling plant (georges and lebrun ). a program for power generation optimization is developed by sega (anon). zhang et al. ( ) used sega’s energy optimization program (eop) to analyze the operation of a cogeneration power plant and found the optimal operation can save total costs by . % compared to the original operation. however, research on the method for optimizing the operational combination of heat source equipments in central heating/cooling plants for buildings can seldom be found. corresponding to a requirement of heating/cooling, many different heating cooling source combinations can satisfy the requirement. it is necessary to select an optimal combination for the purpose of ensuring energy efficiency. however there are so many different combinations of multiple heating/cooling source equipments that it is difficult, even impossible, to check the performance of all the possible combinations experimentally on an actual plant. therefore it is necessary to find a method to automatically check the performance of all possible combinations and determine the optimal combination. simulation is considered to be a powerful tool to automatically check the performance of a building and its systems (wang and yoshida, ). this paper focuses on developing a method for determining optimal running combination of multiple heating/cooling equipments using simulation. for the purpose of validating the method proposed, then the method is applied to an actual district heating/cooling plant located in osaka japan, which consist of two absorption chiller/heaters, one centrifugal chiller, one synthesis and structural characterization of sno electron transport layer in perovskite solar cells synthesis and structural characterization of sno electron transport layer in perovskite solar cells hongzhou dong , chenglin gao , xichang bao , liyan yu , lifeng dong , . college of materials science and engineering, qingdao university of science and technology, qingdao , china . cas key laboratory of bio-based materials, qingdao institute of bioenergy and bioprocess technology, chinese academy of sciences, qingdao , china . department of physics, hamline university, st. paul, mn , usa energy crisis and environmental pollution become the problems that more and more researchers focus on, and perovskite solar cells have attracted most interesting due to their high-power conversion efficiency (pce) of over % [ ]. tio is usually utilized as electron transporting layer for perovskite solar cells, but its high synthesis temperature of °c has limited its applications in flexible electronics. in comparison to tio , sno can be synthesized through low temperature solution process and exhibit similar or even better electrical and optical properties. in this study, we synthesize sno by spin-coating followed by thermal treatment at °c and study its structural and photoelectrical properties. figures a-b demonstrate schematic structure and energy band diagram of a perovskite solar cell, respectively. for the fabrication of a solar cell, fluorine doped tin oxide (fto) glass substrate was firstly cleaned and treated with o plasma to improve wettability. sno was then synthesized on the surface of the fto substrate by spin-coating sncl · h o precursor at rpm for s, followed by thermal treatment at °c for min. then, perovskite ch nh pbi and thiophene copolymer p as hole transporting layer [ ] were formed on top of sno layer by spin-coating successively. at the end, the sample was taken into a thermal evaporation chamber, where ag electrode was deposited. surface morphology of the films was characterized by scanning electron microscopy (sem, hitachi s- ). current-voltage (j-v) curves of solar cells were tested under mw/cm illumination of am . g with a newport solar simulator through a keithley source measurement unit [ ]. as shown in figure a, a compact sno nanocrystalline film is formed on the fto substrate with a thickness of circa nm (figure c). figure b shows high quality perovskite ch nh pbi film with relatively large grains and excellent surface coverage is coated on the top of the sno layer. as given in figure d, short-circuit current density (jsc), open-circuit voltage (voc), fill factor (ff) and pce of the perovskite solar cells are . ma/cm , . v, . %, and . %, respectively. this indicates that sno film can be successfully synthesized by low temperature solution process to replace tio or organic pedot/pss as electron transporting layer for perovskite solar cells, and the pce can be improved by optimizing parameters of solution process [ ]. references: [ ] qianqian zhu et al, acs appl. mater. interfaces ( ), p. . doi: . /s x microsc. microanal. (suppl ), © microscopy society of america https://doi.org/ . /s x downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s x https://www.cambridge.org/core https://www.cambridge.org/core/terms [ ] hugo bronstein et al, j. am. chem. soc. ( ), p. . [ ] chenglin gao et al, j. mater. chem. c ( ), p. . [ ] this research was supported by the national natural science foundation of china ( & ), the international science & technology cooperation program of china ( dfa ), the department of science and technology of shandong province ( ggx ), and shandong province higher educational science and technology program (j la ). figure . schematic structure of a perovskite solar cell (a) and corresponding energy band diagram (b). figure . top-view sem images of sno film coated on fto substrate (a) and perovskite ch nh pbi film coated on the sno film (b). cross sectional sem image (c) and j-v curve (d) of the perovskite solar cell. microsc. microanal. (suppl ), https://doi.org/ . /s x downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s x https://www.cambridge.org/core https://www.cambridge.org/core/terms regional environmental governance in europe: old and new challenges yet to take up available online at www.sciencedirect.com - © published by elsevier ltd. doi: . /j.sbspro. . . procedia social and behavioral sciences ( ) – regional environmental governance: interdisciplinary perspectives, theoretical issues, comparative designs (regov) regional environmental governance in europe: old and new challenges yet to take up ronan uhel* european environment agency, kongens nytorv , copenhagen k, denmark abstract this contribution is based on a set of reflections presented at the regov workshop. these reflections were offered as part of a panel discussion around the topic “what is a region?” additional presentations provided in the context of this panel discussion include those of anssi paasi, university of oulu (this volume), anthony lehmann, university of geneva, and john allen, open university (uk). webcasts of all presentations are available at http://www.reg-observatory.org/outputs.html. © published by elsevier ltd. keywords: european union; european environment agency; territorial cohesion; administrative regions. what i would like to share with you is what my daily reality is really. i am a civil servant of the european union but i am neither a policy maker nor a scientist. i am an analyst with one foot in politics and one in science, and my job is to help policy making with the most up-to-date and relevant knowledge. when you have to do that in the field of environmental policies, today you are talking about what is really at the heart of society: you are talking about growth, development, economic and financial crises, and the energy crisis. you are not just talking about the birds in the forest. you are very much at the heart of what is the fabric of society. when you are in this situation, particularly at the european union scale, the difficulty is to understand who is doing what in this politics of scale, for eu politics is very much a politics of interacting levels. these levels of politics reflect in turn the interests of particular communities, which you will find either in a region or in interest groups. since these interest groups extend across business, science, and government, defining what can be an entity that might correspond to the most adequate stewardship of a particular set of assets gets very complicated at the european scale. why is this so? one of the reasons relates to the complexity of defining increasingly recognized mutual interdependence across government levels against the background of europe’s so-called internal market. today you can have local markets for fish in, say, the netherlands, yet the conditioning of a species may have been done in the south of spain, the fish was caught next to the harbor in the netherlands, and in between you have eu subsidies * corresponding author. e-mail address: ronan.uhel@eea.europa.eu. open access under cc by-nc-nd license. open access under cc by-nc-nd license. http://creativecommons.org/licenses/by-nc-nd/ . / http://creativecommons.org/licenses/by-nc-nd/ . / ronan uhel. / procedia social and behavioral sciences ( ) – supporting the transport from the dutch fishing grounds to the spanish conditioning factory and back to the consumption market in the netherlands. this is called a trans-european network. when you look at the realities, you have around million euro per year for the next six years earmarked for these so-called trans-european networks. what does it boil down to? when we look at the dynamics at work in europe, they are profoundly business-oriented, but they are also rooted in european territorial dependencies. the irony of it is that for the first years of eu politics, these territorial dynamics were nowhere to be found in eu government structures, not even the eu treaty. socio-economic cohesion was at the heart of the previous eu treaty. since the adoption of the new treaty the notion of territorial cohesion has been brought in and put on an equal footing. i am calling on the scientific community today to come and study the realities of this territorial cohesion principle in the european union. because this is the principle that is going to help us bring the currently virtual understanding of european dynamics into governance reality in the context of what we can call socio-ecological systems. of course, the boundaries of these socio-ecological systems are extremely complicated to delineate. but it is imperative, since when you consider the realities of europe from a policy science standpoint, you will notice that percent of the eu budget is used for some form of territorial development, be it through regional policies or agricultural policies. this is an absolutely enormous share, and yet the irony is that the only policy that is not under the competence of the eu is physical planning. what you find are realities that are amazingly contrasting when you try to bring them into the context of managing all these dynamics. the european union finances but does not control; it subsidizes but does not hold people accountable. these are the realities i confront on a daily basis, because as an analyst of the european environmental agency, i am not spending most of my time in dialogue with non-governmental organizations in charge of nature conservation. on the contrary, i spend most of my time trying to work together with colleagues in the european commission and member states, who are dealing with regional policies and interregional projects, trying to define eu cohesion policy and finding ways to translate all these dynamics. the only mechanism we have at our disposal for the time being is to take units of administrative regions, the so- called nuts. yet this is far from optimal since it is only an administrative representation, not a political reality, of how we need to manage all these developments and dynamics at the european scale. there are currently more than highly administrative nuts regions in europe. these regions themselves are coming to realize that their dependency on european dynamics is so high that they need to be involved in the political structures and policy- making processes at the european level. indeed, a look at some statistics of the past - years shows that in terms of lobbying structures, brussels is approaching washington d.c. this is not lobbying by business. instead, the highest rate in terms of lobbying comes from regional authorities. bavaria, the province of milan, all of them are investing in staff in brussels to lobby eu politics. and this reality is very important because this is where you realize that something is changing. regions are coming to the fore. so much so that today you have the committee of regions in the eu governing system. what does this committee do? its role is largely consultative and advisory, hence much smaller than that of the european parliament, the european council, and national governments. however, you come to realize as well that the committee’s voice is being heard more and more. i have spent over the recent years more and more time with the committee of regions, trying to understand really what is its main motivation. is it really an issue of this politics of scale, of regions saying we want our share of the cake; we want to be in control? of course there is this aspect, but there is also a huge demand for understanding what is happening to entities that are purely administrative, that are facing many new developments, and that recognize that they are in a difficult situation. let me give you the example of climate change adaptation. many local and regional authorities in europe today are affected by some impacts of climate change such as flooding, heat waves, droughts, or coastal erosion. the cost of damages is much beyond what they can afford. climate change adaptation relates to what politics hates: the long- ronan uhel. / procedia social and behavioral sciences ( ) – term and uncertainty. yet local and regional authorities are not only asking for better knowledge, they are asking for solidarity. in this context, the research project espace examined local-regional realities of organizing regional responses to climate change adaptation. the first conclusion of that project, after a survey, many consultations, and participatory processes with many stakeholders at the regional level, was that our current government structures are completely obsolete and inadequate to tackle the issue of adaptation. i conclude by suggesting that this is not only a great topic for research studies, it also serves as a perfect example of what we are confronted with in the context of regional environmental governance. arxiv:astro-ph/ v jan ar x iv :a st ro -p h/ v j an energy crisis in the superbubble dem l (n d) randall l. cooper , , mart́ın a. guerrero , , you-hua chu , c.-h. rosie chen , bryan c. dunne astronomy department, university of illinois, west green street, urbana, il abstract superbubbles surrounding ob associations provide ideal laboratories to study the stellar energy feedback problem because the stellar energy input can be es- timated from the observed stellar content of the ob associations and the inter- stellar thermal and kinetic energies of superbubbles are well-defined and easy to observe. we have used dem l , also known as n d, to carry out a detailed case study of the energy budget in a superbubble, and we find that the expected amount of stellar mechanical energy injected into the ism, ( ± ) × ergs, exceeds the amount of thermal and kinetic energies stored in the superbubble, ( ± ) × ergs. clearly, a significant fraction of the stellar mechanical energy must have been converted to other forms of energy. the x-ray spectrum of the diffuse emission from dem l requires a power-law component to explain the featureless emission at . – . kev. the origin of this power-law component is unclear, but it may be responsible for the discrepancy between the stellar energy input and the observed interstellar energy in dem l . subject headings: ism: bubbles — ism: individual (dem l ) – stars: winds, outflows – supernovae: general – x-ray: ism . introduction massive stars inject large amounts of mechanical energy into the ambient interstellar medium (ism) via fast stellar winds and supernova explosions. the stellar energy feedback astronomy department, university of illinois, w. green street, urbana, il ; rcooper @astro.uiuc.edu, mar@astro.uiuc.edu, chu@astro.uiuc.edu c-chen@astro.uiuc.edu, car- olan@astro.uiuc.edu now at department of astronomy, harvard university, rcooper@cfa.harvard.edu now at instituto de astrof́ısica de andalućıa (csic), spain. – – alters the physical conditions of the ism and consequently may regulate the formation of future-generation stars. to gain a better understanding of the physical structure and evolu- tion of the ism in a galaxy, it is necessary to investigate empirically the conversion efficiency of stellar mechanical energies into interstellar kinetic and thermal energies. massive stars usually form in groups such as ob associations, and their fast stellar winds and supernova ejecta collectively sweep up the ambient ism to form superbubbles (mac low & mccray ). superbubbles provide excellent laboratories to study the effects of stellar energy feedback on the ism because the kinetic and thermal energies in a superbubble are well-defined and can be measured with little ambiguity. superbubbles in the large magellanic cloud (lmc) at kpc are particularly well suited for such studies, as their stellar content and ism can be observed in great detail with little foreground extinction. we have chosen the superbubble dem l (davies, elliott, & meaburn ) in the lmc for a detailed study of the interaction between its stars and the ambient ism. dem l , also known as n d (henize ), hosts two ob associations, lh and lh (lucke & hodge ). the stellar content of these two ob associations and the dy- namics of the superbubble have been analyzed in detail by oey ( a) and oey & smedley ( ). they conclude that lh and lh are both young, ∼ × yr old. the diffuse x-ray emission from the hot interior of dem l was detected by einstein and rosat observations (chu & mac low ; dunne, points, & chu ), but high-quality spectra of the x-ray emission have been provided only by xmm-newton observations. the emission line features in the x-ray spectra suggest an overabundance in oxygen and neon which is used to argue for the occurrence of supernova explosions (bomans et al. ). this paper reports our investigation of the energetics of the superbubble dem l . in § we analyze archival xmm-newton observations of dem l to determine the physical properties of the hot gas in the superbubble interior. in § we determine the thermal energy of the hot superbubble interior and the kinetic energies of the ionized and neutral gas in the superbubble shell. in § we compute the stellar wind energy and supernova explosion energy expected from the known stellar content of lh and lh . finally, a discussion of the overall energy budget of the dem l superbubble and our conclusions are given in § . . xmm-newton observations of hot gas in dem l dem l was observed with the xmm-newton observatory on october and november using the epic/mos , epic/mos , and epic/pn ccd cameras (obs. id: ). the two epic/mos cameras were operated in the prime full-window mode for a – – useful exposure time of . ks, and the epic/pn camera was operated in the extended prime full-window mode for a useful exposure time of . ks. the thin filter was used for all observations. we retrieved the xmm-newton pipeline products from the xmm-newton science archive (xsa) and further processed the data using the xmm-newton science analysis software (sas ver. . . ) and the calibration files from the calibration access layer available on december . the event files were screened to eliminate bad events (e.g., events due to charged particles) so that only events with ccd patterns - (similar to asca grades - ) were selected for the epic/mos observations, and events with ccd pattern (single pixel events) were selected for the epic/pn observation. we also screened the event files to remove periods of high background. to assess the background rate, we binned the counts over s time intervals for each instrument in the - kev energy range which is domi- nated by the background. only for a short period of time did the high background, with count rates ≥ . counts s− for the epic/mos or ≥ . counts s− for the epic/pn, affect the observations; events from this high-background period were discarded. the resulting net exposure times are . ks and . ks for the epic/mos and epic/pn observations, respectively. . . spatial analysis we extracted images from the epic/pn and epic/mos observations in the . – . kev energy band, which includes most of the diffuse x-ray emission from dem l . these images were then combined to obtain a higher s/n ratio image and to reduce the null exposure in the gaps between ccds (the satellite was not dithered during the observations). the resulting raw epic image is presented in fig. a. this image was further adaptively smoothed using gaussian profiles with fwhm ranging from ′′ to ′′ and divided by a normalized exposure map to remove the vignetting of the telescope and sensitivity variations of the instruments. a grey-scale presentation of this adaptively smoothed epic image is shown in fig. b. for comparisons, an hα image of the same region is displayed in fig. c, and the x-ray contours extracted from the smoothed epic image are overplotted on the hα image in fig. d. diffuse x-ray emission from the interior of dem l is clearly detected. the brightest x-ray emission region is coincident with the ob association lh , peaking particularly at the xmm-newton science archive is supported by esa and can be accessed at http://xmm.vilspa.esa.es/xsa. – – the bright wolf-rayet star hd . the x-ray peaks coincident with bright stars may be dominated by stellar emission; therefore, emission from these peaks is excluded from our analysis of diffuse x-rays. the diffuse x-ray emission shows a rough limb-brightened morphology in the main body of the superbubble, with the brightest diffuse x-ray emission projected interior to the brightest hα emission regions of the shell. faint diffuse x-ray emis- sion is detected to the north and southwest of the main body; however, these faint x-ray extensions do not necessarily imply blowouts, as they are bounded by faint hα filaments ex- ternally. the superbubble dem l must be in an inhomogeneous ism, and the variations in the hα surface brightness reflect the density variations in the ambient ism. the rough correspondence between the diffuse x-ray surface brightness and the nebular hα surface brightness suggests that a mixing of the dense, cooler, superbubble shell gas into the hot interior has occurred. . . spectral analysis the x-ray spectrum of dem l is extracted from only the event file of the epic/pn camera because its sensitivity is greater than that of the epic/mos cameras. the source aperture, marked in fig. a, includes a large elliptical region that covers the main body of dem l and the north extension and a smaller square region that covers the southwest extension; these two regions together encompass all diffuse x-ray emission within the super- bubble. the background contribution was assessed using an aperture exterior to dem l with similar area to the source aperture. all point sources were excised from the source and background apertures. a circular region that includes most stars in lh is also excluded from the source aperture to minimize the stellar contribution to diffuse emission. after the background subtraction, a total of ∼ , counts are detected in the source aperture. some residuals of the background subtraction are noticeable at the energy of the al kα fluoresce line at ∼ . kev. the energy range . - . kev, thus, has been omitted in the subsequent spectral analysis. the background-subtracted epic/pn spectrum of dem l , shown in fig. , peaks at . – . kev, with a bright shoulder at ∼ . kev and a weaker peak at . – . kev. above . kev, the spectrum is featureless with emission detected up to . kev. the overall spectral shape indicates thermal plasma emission, with spectral features corresponding to the he-like triplet of o vii at ∼ . kev, the h-like o viii line at ∼ . kev, and the he-like triplet of ne ix at ∼ . kev. therefore, we have adopted the mekal optically- thin plasma emission model (kaastra & mewe ; liedahl, osterheld, & goldstein ) with / z⊙ abundances as appropriate for the lmc and the absorption cross-sections from – – balucińska-church & mccammon ( ). the spectral fits are carried out using xspec ver. . . by folding the model spectrum through the epic/pn response matrices and comparing the modeled spectrum to the observed spectrum in the . – . kev energy range. the χ statistics are used to determine the best-fit model. the best-fit mekal model with / z⊙ abundances is very unsatisfactory (reduced χ = . ), failing to fit the spectrum at – kev and showing large residuals at the ne ix lines at ∼ . kev. adding a second thermal component at a higher temperature can improve the spectral fits significantly (reduced χ = . ), but the temperature of the second component is pegged at the upper limit allowed by xspec, i.e., kt = kev. a thermal component at such a high temperature is not expected in the ism; furthermore, it is dominated by bremsstrahlung emission of which the spectral shape is featureless and similar to that of a power law. therefore, we have added a power-law component, instead of a second thermal component, and the reduced χ is lowered to . for the best-fit model. the large residuals at the ne ix lines remain, and they can be minimized only if the ne abundance is allowed to vary. by increasing the ne abundance by a factor of (i.e., solar ne abundance and / solar for the other elements), we are able to obtain a best-fit model with a reduced χ of . , as shown in fig. . this confirms the enhanced ne abundance suggested by bomans et al. ( ); however, we do not find compelling evidence for an enhanced o abundance, which has also been suggested by bomans et al. ( ). in our best-fit model for the diffuse x-rays from dem l , the thermal component dominates the emission below kev with a temperature kt of . ± . kev, an absorption column density of ( . ± . )× h-atom cm− , and a normalization factor a = ( . ± . )× − cm− . the power law component dominates the emission from to kev and has a photon index Γ of . ± . . the observed flux of diffuse x-ray emission from dem l is . × − ergs cm− s− and the x-ray luminosity is ∼ × ergs s− in the . – . kev band. the thermal emission accounts for ∼ % of the observed luminosity (but ∼ % of the total number of detected photons). . energy content of dem l for a superbubble like dem l , we expect the stellar mechanical energy injected into the ism to be stored in the thermal energy of its hot interior and the kinetic energy of the dense, swept-up shell. as the ionization front might be trapped in the swept-up shell, both the normalization factor a is defined to be a= × − ∫ n e dv / πd , where d is the distance, ne is the electron number density, and v is the volume. – – ionized and neutral gas in the superbubble shell must be considered. below we examine separately the thermal energy of the hot interior and the kinetic energies of the ionized shell gas and associated h i gas. . . thermal energy of the superbubble interior the thermal energy of the hot gas in a superbubble is eth = ( / )kt nǫ v , where t is the plasma temperature, n is the total particle number density, ǫ is the volume filling factor of the hot gas, and v is the volume interior to the superbubble. assuming a canonical helium to hydrogen number density ratio of nhe/nh = . , the total particle number density, approximated by the sum of electron density, hydrogen density, and helium density, is n ∼ ne + nh + nhe ∼ . ne. for a given volume filling factor ǫ , the rms ne can be derived from the normalization factor a of the best-fit model: ne = × d(πa/ǫ v ) / . for a distance of d = kpc, a normalization factor of a = ( . ± . ) × − cm− , and a volume v = . × cm (approximated by a × × pc ellipsoid), we find ne = ( . ± . ) ǫ − / cm − . the total mass of the hot gas in the superbubble is . × ǫ / m⊙, and the total thermal energy of the hot gas is eth = ( . ± . ) × ǫ / ergs. the filling factor ǫ is most likely between . and . . for ǫ = . , ne = . ± . cm− , the hot gas mass is m⊙, and eth = ( ± ) × ergs. the cooling timescale of the hot gas tcool is ∼ ( / )nkt /Λ(t ), where Λ(t ) is the cooling function for gas at temperature t in units of ergs cm− s− . for a plasma temperature of a few × k, Λ(t )/n h = × − ergs cm s− for / z⊙ abundances (dalgarno & mccray ). with nh ∼ . ne, n ∼ . ne, and kt = . ± . kev, the cooling timescale tcool is ∼ myr. since the cooling timescale is much larger than the age of the ob associations lh and lh , ∼ myr, only a negligible amount of thermal energy has been radiated away. . . kinetic energy of the ionized superbubble shell the mass of the ionized superbubble shell can be derived from the hα luminosity, lhα. the hα flux from dem l is fhα = ( ± ) × − ergs s− cm− (kennicutt & hodge ). for a distance of d = kpc, lhα = πd fhα = ( . ± . )× ergs s− . in addition, for ionized gas at temperatures of ∼ k, lhα = . × − nenpv ǫ ergs s − , where ne and np are the particle number densities of electrons and protons in units of cm − , respectively, v is the volume of the region in units of cm , and ǫ is the volume filling factor. again, we – – approximate the superbubble volume by a × × pc ellipsoid, and the volume is v = . × cm . helium is most likely singly ionized, thus ne = . np = ( . ± . ) ǫ − / cm− . the total mass of the superbubble shell is m = . nev ǫ mh, where mh is the mass of a hydrogen atom. using the rms ne derived from lhα, we find the superbubble shell mass to be m = ( . ± . ) × ǫ / g = ( . ± . ) × ǫ / m⊙. the expansion velocity of the dem l superbubble has been measured in the hα line to be vexp ∼ km s − (meaburn & terrett ). thus, the kinetic energy in the ionized superbubble shell is ekin = mv exp = ( . ± . ) × ǫ / ergs. if the thickness of the ionized superbubble shell is / of the radius, then the filling factor of shell gas is ǫ = . , the ionized shell mass is m ∼ × m⊙, and the ionized shell kinetic energy is ekin ∼ × ergs. . . kinetic energy of associated h i gas the kinetic energy of the neutral gas in the swept-up shell can be derived from obser- vations of the -cm line emission from the h i gas. such observations of dem l have been extracted from h i surveys of the lmc made with the australia telescope compact array (atca) and the parkes observatory -m telescope, where single-dish observations from the parkes telescope have been combined with the atca data to “fill-in” low spatial frequencies not observed by the interferometer. the atca and parkes observations are detailed in kim et al. ( ) and kim et al. ( ), respectively. the kinematics of the h i gas can be determined from the position-velocity plots in fig. . the h i gas shows a broad velocity profile centered at the systemic velocity of vhel ∼ km s − and with a width of ∼ km s− , corresponding to twice the expansion velocity measured in hα emission, but no clear expanding shell structure can be identified. the h i channel maps (dunne, chu, & staveley-smith ) and interstellar absorption observations of stars in dem l (wakker et al. ) indicate that the h i velocity structure is rather complex and some velocity components may not be physically associated with the superbubble. a total -cm line flux density of jy is measured from the combined radio observa- tions within the dotted polygon outlined in the h i column density map in fig. . given the lmc distance of kpc, we estimate a total h i mass of × m⊙ from this flux density. the total kinetic energy of the h i gas can be approximated by / of the second moment of the integrated velocity profile, assuming that the motion is isotropic. this estimated kinetic energy is ∼ × ergs. we can also determine the h i kinetic energy using the total h i mass and the expansion velocity of the superbubble shell; the resulting kinetic energy is . × ergs, compatible with the h i kinetic energy estimated from the second moment – – of the velocity profile. note that these h i mass and kinetic energy estimates should be considered as upper limits, as some of the h i gas may not be physically associated with the superbubble. . stellar energy injected into dem l stellar mechanical energy is injected into the ambient ism via fast stellar winds and supernova explosions. below we determine the contributions of these two types of stellar energy feedback. . . stellar wind energy to determine the stellar wind energy injected into dem l , we consider the most luminous stars in the ob associations lh and lh given by oey & smedley ( ). the spectroscopically determined spectral types of these stars are matched with the theoretical models of schaerer & de koter ( ) to assess the stellar mass m, mass loss rate ṁ , and stellar wind terminal velocity v∞. since zlmc ∼ / z⊙, we apply the necessary corrections to the listed theoretical values of ṁ and v∞ for low metallicity stars as described in schaerer & de koter ( ). from these data, we estimate the stellar wind luminosity by lw = ( / )ṁv ∞ . the metallicity-corrected parameters and mechanical luminosities of the stars are listed in table in the same order as given in table of oey & smedley ( ). we calculate the total mass loss rate to be . × − m⊙ yr − and the total stellar wind luminosity to be . × ergs s− . thus, for an age of ∼ myr (oey & smedley ), the total stellar mass loss is ∼ m⊙, and the total wind energy input is about ( ± ) × ergs. . . supernova energy to estimate the number of stars that have already exploded as supernovae, we use the combined mass function of lh and lh . ubv photometry of stars in lh and lh is available from oey ( a). the mass of each main sequence star is determined by comparing its location on a color-magnitude diagram (cmd) to the evolutionary tracks of stars with different masses. as the reddening is not known for individual stars, we use the extinction-free magnitude w = v − dm − (b − v )av /e(b − v ) and reddening-free color q = (u −b)−(b −v )e(u −b)/e(b −v ), where dm = . is the distance modulus of the – – lmc, e(u − b)/e(b − v ) = . , and av /e(b − v ) = . . fig. shows the reddening- free cmd of lh and lh , where the evolutionary tracks of main sequence stars with z = . z⊙ provided by lejeune & schaerer ( ) are plotted for initial masses of , , , , , , , , and m⊙. stars in each mass bin are counted. we assume a salpeter initial mass function for lh and lh : f (m) = km− . , where k is a constant that can be determined from the star counts. the number of stars with masses between mmin and mmax is n = ∫ mmax mmin f (m) dm. for a mmin of – m⊙ and a mmax of – m⊙, we find k = ± . this constant is insensitive to the choice of mmax but rather sensitive to the choice of mmin; the error bar reflects the uncertainty caused by different mmin. the number of stars with masses greater than m⊙ is ∫ m⊙ m⊙ f (m) dm = ± . from table , we find stars with masses greater than m⊙, so the number of stars that have exploded in supernovae is ( ± ) − = ± . we have chosen to count main-sequence stars in the – m⊙ range because the evolutionary tracks of such stars are well constrained by the empirically derived relationship between stellar masses and spectral types and are not subject to the uncertainties for the most massive stars (e.g., aloisi, tosi, & greggio ). we have compared the evolutionary tracks of stars in the – m⊙ range between the geneva models (schaerer, meynet, maeder, & schaller ) and the padua models (fagotto et al. ), and find that they are indeed similar. assuming that each supernova releases about ergs of explosion energy, the total supernova energy input is approximately ( . ± . ) × ergs. . energy budget of the superbubble dem l the energies stored in the superbubble dem l and the stellar energy input are summarized in table . the values and error bars of the thermal and kinetic energies take into account the most probable range of filling factors. the stellar energy input includes contributions from fast stellar winds and supernovae. the superbubble energy includes the thermal energy of its hot interior and the kinetic energy of the superbubble shell. it is immediately clear that the expected amount of stellar energy injected into the ism is ∼ times as large as that observed in the superbubble. previously, observed dynamics of bubbles blown by single stars or superbubbles have been compared with pressure-driven bubble models by weaver et al. ( ) or variations of the thermal energy of the ionized superbubble shell is not included in the energy budget discussion because the superbubble shell is photoionized and the thermal energy is provided by the uv radiation of the ob associations. – – such models, and it has been commonly concluded that the observed stellar wind strength is too high for the observed bubble dynamics or that the bubble/superbubble shell expands too slowly for the given stellar wind strengths (e.g., garćıa-segura, langer, & mac low ; oey b; nazé et al. ). these results are equivalent to what we have found in dem l , i.e., the stellar mechanical energy injected into the ism exceeds the energies storied in the superbubble. more specifically, according to the weaver et al. ( ) model, the km s− expansion velocity and pc radius of dem l indicate a dynamic age of myr, which is shorter than the age of the ob associations lh and lh . the mass of the ionized superbubble shell consists of the material swept up from the superbubble interior, thus the volume and mass of the h ii gas given in § . imply an ambient density of ∼ h-atom cm− . the wind mechanical luminosity required by weaver et al. ( ) for dem l is . × ergs s− , and the total energy required during the myr dynamic time is ∼ × ergs, which is much smaller than the total stellar energy expected from lh and lh . evidently there is an energy crisis: the observed interstellar energies cannot account for all the stellar energy injected into the ism. several mechanisms may drain energies from a superbubble. the most obvious mechanism is a superbubble blowout or breakout, in which the interior hot gas spews out, directly reducing the thermal energy and pressure of the superbubble interior. however, no blowouts are obvious in dem l . as shown in fig. , the extended diffuse x-ray emission from dem l is completely bounded by outer, curved hα filaments, in sharp contrast to the blowout of the superbubble dem l , also known as n , in which the diffuse x-ray emission extends beyond open, streamer-like hα filaments (chu et al. ). another mechanism that may drain the internal energy of a superbubble is the evapo- ration of dense cooler gas into the hot interior. in addition to the dense ionized superbubble shell, dem l contains dense cloudlets with ionized surface layers, as revealed in high- resolution hst wfpc hα images (chen et al. ). the main energy loss would occur at the interface layer between the k hot gas and the k cool gas because the cooling rate is the highest for temperatures of a few × k. we may estimate the energy loss due to cooling from interface layers. assuming that the interface layers are in pressure equilibrium with the hot interior gas, their electron number density would be . – . cm− . the total volume of the interface layers is nevertheless unknown because no interface layer has ever been spatially resolved observationally and even the existence of heat conduction and mass evaporation may be questionable (shelton ). the spatial extent of an interface layer can be estimated from the relative locations of diffuse x-ray emission and the optical shell of a bubble or superbubble. the highest-quality x-ray observations of wind-blown bubbles are the chandra observation of ngc and the xmm-newton observations of s (gruendl, – – guerrero, & chu ; chu et al. ). while ngc shows no appreciable separation between the outer edge of the diffuse x-ray emission and the outer edge of the optical shell, s shows a gap of – ′′ (or . to . pc), which contains the dense ionized gas shell and the interface layer. the interface layer must be less than . pc in thickness. adopt- ing this upper limit of the interface layer thickness for dem l , the volume occupied by the interface layer is no more than . % of the total volume. using a cooling function Λ( k)/n h ∼ × − ergs cm s− appropriate for the lmc metallicity (dalgarno & mccray ), the current cooling rate would be × ergs s− . if the superbubble has been evolving with the radius ∝ tη, where t is the age and η is a constant (e.g., η = . for the weaver et al. model), then the volume has been growing ∝ t η, and the total energy radiated away in myr by the interface layer would be × ( η + )− ergs. if η = . , the total radiative loss is ∼ . × ergs. this generous upper limit for radiative loss is non-negligible but not sufficiently significant in the energy budget. therefore, radiative loss in the interface layer between dense cold gas and the hot superbubble interior cannot be the cause of the energy discrepancy. where did the stellar energy go if it is not converted into the thermal and kinetic energies of the ism? the interaction between a fast moving plasma, being it tenuous stellar winds or dense supernova ejecta, and the ambient ism is a complex magnetohydrodynamic problem (spitzer ). it is perhaps an oversimplification to assume that supernova ejecta and fast stellar winds are thermalized in the hot interior of a superbubble. in fact, the xmm-newton x-ray observations of dem l reveal a possible mechanism that may play an important role in the energy budget. our analysis of the x-ray spectrum of the diffuse emission from dem l indicates that not all emission originates from a thermal plasma; a power-law component is needed to explain the emission in the . – . kev range. this power-law component cannot originate from unresolved point sources, as the smoothed x-ray image in the . – . kev band displayed in fig. shows that this hard x-ray emission is diffuse. it is possible that this power-law component originates from the interactions of supernova ejecta and fast stellar winds with the hot interior of the superbubble, but the exact origin is unclear. it is unlikely that this power-law component represents a synchrotron x-ray emission similar to those seen in young supernova remnants such as sn (koyama et al. ) and cas a (vink & laming ) and the superbubble dor c (bamba et al. ) for two reasons. first, the x-ray photon index of dem l , Γ = . ± . , is lower than those observed in the other objects, Γ ∼ . second, the synchrotron x-ray emissions from young supernova remnants and dor c show limb-brightened morphologies because the relativistic particles are accelerated in the shocks, but the power-law x-ray emission from dem l does not show enhancement along the edge (see fig. ). observations of more superbubbles are needed to determine whether a power-law component is commonly needed to model the spectra of – – their diffuse x-ray emission. future theoretical models of superbubbles need to solve the plasma interaction problem realistically instead of making simplifying assumptions about shocks and converting mechanical energy into only kinetic and thermal energies, so that true progress in the understanding of bubbles and superbubbles can be made. yhc acknowledges the support of nasa grant nag - . we thank the referee for prompt reading and providing useful suggestions to improve this paper. we also thank yaël nazé for her critical reading of the paper. – – references aloisi, a., tosi, m., & greggio, l. , aj, , balucińska-church, m., & mccammon, d. , apj, , bamba, a., ueno, m., nakajima, h., koyama, k. , apj, in press (astro-ph/ ) bomans, d. j., rossa, j., weis, k., & dennerl, k. , in iau symposium, no. , ed. k. a. van der hucht, a. herrero, & c. esteban (san francisco: asp), chen, c.-h. r., chu, y.-h., gruendl, r. a., & points, s. d. , aj, , chu, y.-h., guerrero, m. a., gruendl, r. a., garćıa-segura, g., & wendker, h. j. , apj, , chu, y.-h., & mac low, m.-m. , apj, , chu, y.-h., mac low, m. m., garćıa-segura, g., wakker, b., & kennicutt, r. c. , apj, , dalgarno, a., & mccray, r. a. , ara&a, , davies, r. d., elliott, k. h., & meaburn, j. , mmras, , dunne, b. c., chu, y.-h., & staveley-smith, l. , in preparation dunne, b. c., points, s. d., & chu, y. , apjs, , fagotto, f., bressan, a., bertelli, g., & chiosi, c. , a&as, , garćıa-segura, g., langer, n., & mac low, m.-m. , a&a, , gruendl, r. a., guerrero, m. a., & chu, y.-h. , in preparation henize, k. g. , apjs, , kaastra, j. s., & mewe, r. , legacy, , , heasarc, nasa kennicutt, r. c., jr., & hodge, p. w. , apj, , kim, s., staveley-smith, l., dopita, m.a., freeman, k.c., sault, r.j., kesteven, m.j., & mcconnell, d. , apj, , kim, s., et al. , apjs, , – – koyama, k., petre, r., gotthelf, e. v., hwang, u., matsuura, m., ozaki, m., & holt, s. s. , nature, , lejeune, t., & schaerer, d. , a&a, , liedahl, d. a., osterheld, a. l., & goldstein, w. h. , apj, , l lucke, p. b., & hodge, p. w. , aj, , mac low, m., & mccray, r. , apj, , meaburn, j., & terrett, d. l. , a&a, , nazé, y., chu, y.-h., points, s. d., danforth, c. w., rosado, m., & chen, c.-h. r. , aj, , oey, m. s. a, apjs, , oey, m. s. b, apj, , oey, m. s., & smedley, s. a. , aj, , salpeter, e. e. , apj, , schaerer, d., & de koter, a. , a&a, , schaerer, d., meynet, g., maeder, a., & schaller, g. , a&as, , shelton, r. l. , apj, , spitzer, l., jr. , physical processes in the interstellar medium, (wiley-interscience) vink, j. & laming, j. m. , apj, , wakker, b. p., et al. , in preparation weaver, r., mccray, r., castor, j., shapiro, p., & moore, r. , apj, , this preprint was prepared with the aas latex macros v . . – – fig. .— (a) xmm-newton epic image of dem l . the spectrum of the diffuse x-ray emission is extracted from the source aperture consisting of elliptical and square regions marked. the point sources, marked by small circles, and stellar emission from the ob association lh , marked by a larger circle, are excluded from the source aperture. (b) adaptively smoothed and vignetting-corrected x-ray image. the contour levels are at , , . , and σ above the background. (c) hα image of dem l . (d) hα image overplotted with x-ray contours. – – fig. .— xmm-newton epic/pn spectrum of the diffuse x-ray emission from dem l . the best-fit model is overplotted in the solid curve. the thermal plasma component and the power-law component are individually plotted in dashed curves. the bottom panel plots the residuals of the fit. – – fig. .— hα image (left) and h i -cm line map (right) of dem l . both images are overlaid with h i -cm line emission contours at levels of %, %, %, %, and % of the peak. the dotted polygon plotted over the h i map represents the extent of the superbubble and the region over which the h i mass is extracted. we have produced position- velocity plots for two ′-wide slices through the superbubble along the right ascension and declination axes. these slices are shown above and to the right, respectively, of the h i image accompanied with greyscale wedges in arbitrary units. the velocities are heliocentric. the area covered by each slice is indicated by the dashed lines on the hα image. – – fig. .— reddening-free color-magnitude diagram of stars in lh and lh . the photo- metric data of these stars are from oey ( a). see the text for the definition of the reddening-free magnitude w and color q. the evolutionary tracks of stars are from lejeune & schaerer ( ). – – fig. .— xmm-newton pn image of dem l in the . – . kev energy band. the image has been adaptively smoothed with gaussians of fwhm of ′′ to ′′. the emission in the . – . kev range is dominated by the power-law component. the contours are at σ and σ above the background. it is evident that the diffuse emission in this energy range is widespread. the source regions are marked for comparison with fig. a. – – table . stellar data m log ṁ v∞ log lw star id spectral type (m⊙) (m⊙ yr − ) (km s− ) (ergs s− ) l sa- b o iaf - . . l sa- o iii((f)) - . . l s- o ib(f) - . . l n- o . iii((f)) - . . l s- a o : iii(f) - . . l s- o iii(f*) - . . l s- o iii((f)) - . . l s- a o . : v - . . l s- b b : ii: - . . l s- b b . : iii: - . . l n- o . v - . . l n- b iiie - . . l n- o v - . . l s- b . ib - . . l n- o v - . . l s- b iii - . . l n- o v - . . l s- early b:: +neb - . . l n- b . :: v +neb - . . l s- o v((f))e - . . l sa- b . iii - . . l s- b v # - . . l s- b . ve - . . l s- o . v - . . l s- o ve - . . l s- o . v # - . . l s- o v - . . l s- b . v - . . l s- o v - . . l s- b . : v # - . . – – table —continued m log ṁ v∞ log lw star id spectral type (m⊙) (m⊙ yr − ) (km s− ) (ergs s− ) l s- b . v - . . l n- b : v +neb - . . l n- b v - . . l s- o . v - . . l sa- b :: v +neb - . . l s- o . v - . . l sa- a wc · · · · · · · · · · · · l n- b . v +neb - . . l s- o . -b v - . . l s- o . v +neb - . . l n- o . v - . . l s- b . iii +neb - . . l n- o . v - . . l s- b :: v +neb - . . l n- o : ve - . . l s- b :: v - . . l sa- b . v - . . l n- o . v - . . l n- b . v - . . l s- b . :: ve - . . l n- b :: v +neb - . . l n- o . -early be - . . l s- b :: v - . . l n- b :: v - . . note. — # indicates spectral binary candidate. see table of oey & smedley ( ) – – table . energy budget of the superbubble dem l energies amount (× ergs) eth of the hot gas in superbubble interior . ± . ekin of the ionized (h ii) superbubble shell . ± . ekin of the neutral (h i) superbubble shell . ± . total energy observed in the superbubble ± stellar wind energy input in myr ± supernova energy input ± total stellar energy input ± sustainable development — time to act editorial sustainable developmentÐ time to act sustainable development has been adopted as a central environmental strategy for the uk (see, for example, richard grif® ths’ editorial in last november’ s psep, (b ): ). the environment agencyÐ as well as several government departments and non-departmental public bodiesÐ has a speci® c remit to have a regard to sustainable development in discharging its duties. the department of the environment, transport and the regions (detr) has issued a wide-ranging consultation paper asking for comments on everything from measures of sustainability to resource management, transport, tourism, wildlife, research and education. professional bodies and industry also recognize the importance of the concept, and statements of goodwill abound. it appears that the bandwagon is rolling and, given our con® dence in human ability to solve problems, a brighter future should be just round the corner. however, there are three signi® cant questions to be addressed: · what is sustainable development? · what do individuals, organizations and countries need to do to deliver itÐ and if we can work out what to do, will those involved (that is, everybody) have the will to do anything about it? · even if the will exists, can we move to a sustainable situation given the explicit and implicit constraints on the solutions? it would be easy to suggest that since we don’ t know where we’ re going, or who’ s coming with us on the journey, or whether the route to our destination is open, that we’ re unlikely to arrive. on the ® rst question we can make some progress. we can envisage some distant future where human needs are met by solar energy, our population is in balance with the carrying capacity of the planet, everybody is con- tented and wars have been abolished. sustainable development must just be a path between where we are now and where we want to be. simple. except that we don’ t yet appear to have the technology, organization, social skills or scienti® c knowledge to do it, and we may run out of resources trying. in other words, even if we could de® ne sustainable development, making it happen could be beyond us. to the questions above i’ d like to add one moreÐ how should we set about solving the problems? this is more than idle musing. to date, we have in general solved problems of balancing resource use, bene® t and harm by setting limits at the boundaries of activities. a process can be operated provided it doesn’ t release more than a ® xed amount to the environment. implicit in sustainable development is co-ordination and collaboration. for example, it would be logical to move from the current paradigm of once-through materials use (obtain±use±dispose) to the more sustain- able idea of using resources to drive a cycle of use and reuse. this involves taking a systems view of activities that may span several processes, organizations and possibly countries. it also involves the ability to co-ordinate the application of several different technologies. despite the need for co-ordination, there is an inherent fragmentation in the way the problem is being addressed. fragmentation arises naturally from the divisions in the way we organize societyÐ into companies, regulators, univer- sities, regions, countries, chemists, engineers, social scien- tists, etc. there is also a problem of time-scale. long-term thinking in politics is ® ve years, in industry it is the length of a director’ s rolling contract and in the currency exchange markets it is a few weeks (at most). swings of leadership, market sentiment and public opinion mitigate against a clear long-term strategy. a microcosm of these issues exists in the research/ technical community in the ukÐ discipline-based research councils, the tension between fundamental and applied research, the lack of a coherent vision for the research community, the search for well-de® ned value for money in industrial research and so on. initiatives searching for direction (for example, foresight) produce a mixture of clear, sensible consensus and wild dreamsÐ diluting their credibility by not wishing to upset any of the contributors. rapid change is dif® cult because of the substantial inertia of existing systems. new initiatives, philosophies and directions come and go, typically on a ± year time- scaleÐ often without seeming to deliver anything particu- lar. if the research community is to contribute effectively to delivering sustainable development then it will need more than isolated, small-scale initiatives. research must be fostered that crosses disciplines and is not constrained to sit in the traditional academic subject pigeon-holes. to do that, the in¯ uence of numerous interest groups must be loosenedÐ a substantial challenge. yet if we cannot ® nd ways to change the attitudes and work practises of a small, well-educated community, what hope is there with sustainability? not only do we seem to be ill-organized to meet the challenges of sustainable development, but recent history doesn’ t lend any particular weight to the view that we are capable of solving such problems. the energy `crisis’ of the s and s, when exhaustion of fossil fuel reserves was anticipated, led to little more than some energy-ef® ciency measures and a search for more oil. we have so far proved unable to deliver fusion energy, cost-effective solar energy, etc. clearly the time-scale to solve these technical problems is tens or possibly hundreds of years. this is much longer than the attention span of almost all governments. yet, the problems we now face are much more dif® cult than those of years ago. indeed the time required to develop solutions is increasing while, under the weight of growing world population and living standards, the time available to solve them is decreasing. trans icheme, vol , part b, may open access under cc by-nc-nd license. http://creativecommons.org/licenses/by-nc-nd/ . / so what, if anything, does the chemical engineer have to offer? the contents of psep, both in this issue and past issues, can all be seen as being relevant to sustainable development. we can credibly claim core skills that span processing, technology, economic evaluation, human behaviour, risk assessment, systems and control. we are experienced in dealing with complex, many-variable problems. we are brought up to live with uncertainty. however, in the context of sustainable development perhaps our greatest asset is the ability to co-ordinate. with such a cv it would be natural to be at the centre of the debate. despite this, it seems likely that the issue will be driven by social scientists, ecologists, lawyers and economists. so why not do your discipline (and perhaps the planet) a favour? if you have time before the deadline ( may ) you could read and respond to the detr consultation. it doesn’ t matter if you’ re not from the ukÐ a signi® cant issue raised by the consultation is international co-operation and development. the document can be found on the detr web site (http://www.environment.detr.gov.uk/sustainable/ consult /index.htm) or obtained from the detr. if you can’ t respond in time, do watch the site for reports and developments. moreover, further consultation on this dif® cult issue is more than likely. not only can you help to raise the pro® le of chemical engineering, but you may well help the consultation to come to appropriate and realistic conclusions. paul sharratt editorial trans icheme, vol , part b, may hindawi publishing corporation biomed research international volume , article id , pages http://dx.doi.org/ . / / editorial microbial enzymes and their applications in industries and medicine periasamy anbu, subash c. b. gopinath, arzu coleri cihan, and bidur prasad chaulagain department of biological engineering, inha university, incheon - , republic of korea nanoelectronics research institute, national institute of advanced industrial science and technology, - higashi, tsukuba, ibaraki - , japan department of biology, faculty of science, ankara university, tandogan, ankara , turkey department of plant biology and biotechnology, university of copenhagen, copenhagen, denmark correspondence should be addressed to periasamy anbu; anbu @yahoo.com received october ; accepted october copyright © periasamy anbu et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. enzymes are considered as a potential biocatalyst for a large number of reactions. particularly, the microbial enzymes have widespread uses in industries and medicine. the microbial enzymes are also more active and stable than plant and animal enzymes. in addition, the microorganisms represent an alternative source of enzymes because they can be cultured in large quantities in a short time by fermentation and owing to their biochemical diversity and susceptibility to gene manipulation. industries are looking for new microbial strains in order to produce different enzymes to fulfil the current enzyme requirements. this special issue covers ten articles including three review articles, mainly highlighting the importance and applications of biotechnologically and industrially valuable microbial enzymes. m. dinarvand et al. in their paper optimized the condi- tions for overproduction of intraextracellular inulinase and invertase from the fungus aspergillus niger atcc . optimization is one of the most important criteria in devel- oping any new microbial process. response surface analysis is one of the vital tools to determine the optimal process conditions. this kind of design of a limited set of variables is advantageous compared to the conventional method. the response surface methodology was used for this optimization and achieved the increment until times. this study would be highly useful for the potential application in fermentation industries. in this review, n. gurung et al. have made an attempt to highlight the importance of different enzymes with a special focus on amylase and lipase. enzymes generally increase the reaction rates by several million times than normal chemical reactions. lipases play an important role in the food, detergent, chemical, and pharmaceutical industries. in the past, microbial lipases gained significant attention in the industries due to their substrate specificity and stability under varied conditions. amylase is an enzyme that catalyses the breakdown of starch into sugars, abundant in the process of animal and human digestion. the major advantage of microbial amylases is being economical and easy to manip- ulate. currently, much attention is paid to rapid development of microbial enzyme technology, and these enzymes are relatively more stable than the enzymes derived from plants and animals. p. mukherjee and p. roy in their paper have purified and characterized the enzyme hydrocarbon dioxygenase from stenotrophomonas maltophilia pm , which has a broad substrate specificity. they found that the presence of copper induces the enzyme activity to be . -fold higher, and nadh induces the increment to be . -fold. proposed copper enhanced monooxygenase activity and fourier transform- infrared (ft-ir) characterization of biotransformation prod- ucts from trichloroethylene satisfy the production of indus- trially and medically important chemicals and make biore- mediation more attractive by improving the development of this technology. c. huynen et al. in their review paper discuss the importance of protein scaffold to develop hybrid enzymes. biomed research international the paper discusses the use of class a betalactamase as versatile scaffolds to design hybrid enzymes mentioned as betalactamase hybrid proteins (bhps), in which an external polypeptide, peptide, protein, or their fragment is inserted at various suitable positions. the paper highlights further how bhps can be specifically designed to develop as bifunctional proteins to produce and characterize the proteins otherwise difficult to express, to determine the epitope of specific anti- bodies, to generate antibodies against nonimmunogenic epi- topes, and to understand the structure/function relationship of proteins. the hybrid proteins can be applied to produce difficult-to-express peptides/proteins/protein fragments, to map epitopes, to display antigens, and to study protein structure/function relationships. among other applications, bhps could be an important player in biosensors and in affinity chromatography, drug screening, and drug targeting. p. manivasagan et al. in their paper focus on purification and characterization of the protease from streptomyces sp. mab . the authors have optimized the conditions for over- production of protease using response surface methodology. they have also determined the molecular mass of purified enzyme and great activity and stability of enzyme in different ph and temperatures. furthermore, the authors confirmed that the protease has an antioxidant ability. in industries, the poultry waste derived protease will be useful as a protein or as an antioxidant. the paper titled “𝛽-glucosidases from the fungus tricho- derma: an effeicient cellulose machinery in biotechnological applications” is a detailed review on 𝛽-glucosidases which are members of the cellulose enzyme complex described by p. tiwari et al. the authors especially focus on 𝛽- glucosidases from the fungus trichoderma, mostly used for the saccharification of cellulosic biomass for biofuel produc- tion. they describe the enzyme family, their classification, structural parameters, properties, and studies at the genomics and proteomics levels. in addition, by bypassing the low enzyme production with hypersecretory strains, they give an insight on using these strains for renewable energy sources like bioethanol production. they imply the importance of fungal𝛽-glucosidases which might be successful for biofuel production in order to meet the need in energy crisis. a. khoramnia et al. in their paper discuss yeast enzyme application for medium chain fatty acids (mcfas) modifi- cation for industrial purpose and antibacterial applications. the paper focuses on the conceptualization, design, and assay of the enzyme produced from a malaysian strain of geotrichum candidum. with the modification on fatty acid processing using a naturally derived enzyme, a free lauric acid rich mcfas can be obtained which can become a source of antibacterial use for both gram-positive (staphylococcus aureus) and gram-negative (e. coli) bacteria which are difficult microbes due to some of their strains becoming drug resistant. they also describe that the higher lipolysis by the strain specific enzyme is associated with the increased moisture content in the reaction environment on coconut oil hydrolysis. m. a. hassan et al. in their paper discuss isolation of bacillus amyloliquefaciencs and b. subtilis from soil and production and characterization of keratinolytic protease. these bacteria were able to degrade the wool completely within days and also produced the highest enzyme activity. the characterization studies confirmed that the enzyme is stable in a broad range of ph and temperatures. furthermore, they confirmed that the keratinolytic proteases from isolated bacteria are stable in various organic solvents. in this review article, s. c. b. gopinath et al. put different strategies to characterize fungal lipases for their role in industry and medicine. the advantage of fungal lipases is bestowed with their extracellular nature of production thus reducing the complexities and high operation cost comparing to other bacterial enzymes. the authors provide several illustrations to show how lipolysis can be utilized and put strategies for the characterization of fungal lipases that are capable of degrading fatty substances from different sources, with an effort to highlight further applications. this review would contribute to the isolation and characterization of lipase from various fungal sources and application of lipase for medical and dairy industry and degradation of fatty substance from oil spillages. a. knob et al. in their paper focus on xylanses and discuss the purification and characterization of a xylanase produced by penicillium glabrum using brewer’s spent grain as a substrate in their paper. this study is the first report as the characterization of xylanase was carried out by using such an agroindustrial waste. furthermore, the researchers also determined the molecular mass of the purified xylanase, the enzyme activity and stability on various ph and temperature ranges, the optimal enzyme production conditions, and the effect of some metal ions and inhibitors on xylanase activity. the authors concluded that the use of substrate brewer’s spent grain for xylanase production not only decreased the amount of this waste but also reduced the xylanase production cost as desired in biotechnological processes. periasamy anbu subash c. b. gopinath arzu coleri cihan bidur prasad chaulagain submit your manuscripts at http://www.hindawi.com hindawi publishing corporation http://www.hindawi.com volume anatomy research international peptides international journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com international journal of volume zoology hindawi publishing corporation http://www.hindawi.com 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www.econstor.eu energypolicy the energy crisis and the third world by rainer offergeld, bonn* the economic implications of the latest upsurge of the oil prices for the whole world - and for the developing countries in particular - are such as to make a strategy of common responsibility of industrialized and developing countries more urgent than ever, rainer offergeld, federal minister for economic cooperation, elucidates his ideas about such a strategy. n owhere are the common interests, the need for common solutions and the acceptance of a common responsibility by the industrialized and the developing countries more clearly evident than in the sphere of energy. the oil crisis is leading to forfeiture of growth, boosting inflation and causing unemployment in industrialized and developing countries. the enormously increased oil bill of the developing countries - in it will probably be far in excess of $ bn - is the principal cause of the anticipated drastic rise of their current account deficits to about $ bn in . a grievous impairment of their economic development must be apprehended. if not given effective aid, the poorer developing countries in particular will face ruin. preference for private finance some may say that, since the first oil crisis was satisfactorily dealt with, this was too gloomy a picture. but is the situation now really similar to what it was then? when the first oil shock was over the oil monies of the opec states flowed back to the industrialized countries in the form of demand. the current account surplus of the opec states contracted between and from $ bn to $ bn - i. e., the same amount as in , before the first oil price explosion. the industrialized countries adapted themselves quickly to the expanded demand from opec states. this safeguarded the employment situation in many industrialized countries. * federal minister for economic cooperation. - slightly abridged version of a speech, in german language, to the staff of schweizerisches institut fur auslandsforschung. a part of the oil monies flowing back after went into a few developing countries but most developing countries financed their current account deficits mainly by borrowing from private-sector banks. soft credits by way of public development aid, direct investments by the industrialized countries, export credits and balance of payments assistance by the international monetary fund played a smaller role. the imf could only make a minor contribution to the financing of the balances of payments of the developing countries even though it extended its range of instruments after . it was a task to which primarily the big us and european banks applied themselves. the result was that the indebtedness of the developing countries to these banks increased from $ bn in to $ bn in . to give an example, the developing countries owe to us banks a sum of $ bn - i. e., % of the combined equity capital of these banks. the share of the private-sector banks in the financing of deficits of developing countries rose from % in to % in . the reason for the small role of the imf is probably to be found in its attempt to help to bring order into the economic policies of the recipient countries when it provided finance. whether it always set about such attempts with the necessary discretion is not to be discussed here. it is however undeniable that the private deficit financing has not conduced to the ultimately indispensable structural readjustments i n the developing countries by means of which the causes of the imbalances would have been removed. this is one of the objectionable aspects of the preference for private finance. the large-scale recourse to commercial credits had besides, owing to intereconomics, july/august e n e r g y p o l i c y , their stringent terms, an aggravating effect on the indebtedness of the developing countries. the repercussions of the oil price explosion of have been carried forward by many developing countries until now as debit balances in their accounts. it is clear therefore that the starting position for the recent new oil price explosion cannot be compared with that in . a dangerous situation the new situation is fraught with danger. problems do not arise from the debts of the developing countries as such: in an expanding economy these are a correlate of development. but the higher oil prices and the inflation in the industrialized countries will impede the growth process significantly. the developing countries have to spend one-quarter of their export earnings on imports of oil, a good many of them have much more: turkey about ~ %, brazil % , the philippines % and india %. these payments are additional to those for interest on and redemption of old debts. it can no longer be taken for granted that new loans will everywhere be duly serviced and repaid. it will therefore no longer be possible to increase the private bank lendings to any substantial extent. in january-march developing countries borrowed $ . bn from private-sector banks; in the corresponding period of the preceding year the sum had still been $ . bn. the developing countries are on the horns of a dilemma which the former indian minister of finance has expressed in these words: "india can neither afford to pay for her oil imports at the new prices nor do without them." readjustment of economic structures what then is to be done? the time has come to take cognizance of an inexorable fact: the price of oil may seem to us to be high. seen in the light of the tenfold nominal increase in the course of a few years it is "too high". specific problems have ensued from the abrupt oil price hoists in und with price reductions - in real terms - in between. the high prices are however a prerequisite for the tremendous efforts and investments required to search out new sources of oil and develop alternative energy resources. if the estimates about the quantities of oil which will be available in the next two decades and about the energy requirements of our planet are more or less accurate, the time schedule for the transition to other forms of energy would without price increases be even tighter. intereconomics, july/august geared as they are to cheap oil, the consumption patterns and economic structures of the industrialized and developing countries need a prolonged period of adjustment. without the price increases which have now been effected the time scale would probably have become too tight. we shall have to cope with onerous economic and technological tasks. cheap oil in the eighties would probably have rendered these tasks insoluble. this does not mean - it may be added in parenthesis - that all adjustment problems can be solved by market-economic price mechanisms alone. an efficaceous price mechanism presupposes that supply and demand respond to price signals. this is not the case if higher prices induce the suppliers to curtail their supplies - a tendency which has become obvious in regard to the oil market. a second truth calls for plain speaking: the opec oil price policy - which is commonly regarded as the root of all evil - presents such a threat to the world economy because the boosts to inflation from this side worsen the unresolved inflation problems of most industrialized states. internal distribution clashes in the industrialized states and the redistribution in favour of the oil producers are causing an aggravation of the inflation problems which are presenting an unprecedented threat to the world economy today. the vicious circle is in full view: the home-made inflation of the industrialized states compels the opec to raise its prices steeply as this is the only means of increasing the exchange value of the oil relative to industrial products. this is in turn the cause of new price hoists in the industrialized countries. put differently: stable prices in the industrialized states are capable of curbing the rise of the oil prices. a relentless policy of stability is more necessary than ever in the industrialized countries of the west. the main victims of the international inflationary spiral are the oil-importing developing countries. the consequence of the second oil price explosion for them will be a further worsening of their terms of trade in general. the prospects for easing the plight of the million people living in absolute poverty are being impaired. the non-oil developing countries' ability to finance imports - and imports are in most cases indispensable for economic and social progress - is in jeopardy. repercussions on the industrialized states are foreseeable. this being the situation, an adjustment of the economic structures to the changed parameters is the most important task - in the industrialized as well as in energypolicy the developing countries. the causes of the balance of payments crises have to be removed. it has to be assumed in this context that the oil prices will continue to rise in real terms. hence a need to embark on three lines of approach: f i r s t : saving energy wherever possible, especially in the industrialized countries, but also in the developing countries. s e c o n d i y : opening up new sources of energy - everywhere and especially in developing countries. t h i r d i y : creating prerequisites for investment of the surplus capital resources of many opec states. new avenues have to be found for recycling the petrodollars. saving energy by investing per-capita energy consumption is in the industrialized countries a hundred times as high as in the poorest countries - which shows where energy savings will produce results. an american uses twice as much energy as a german and three times as much as a swiss or japanese although the incomes in these countries do not differ much. the industrial structure of a country has certainly a major bearing on its consumption of energy. a comparison of consumption figures therefore does not always serve a useful purpose. but the fact that in the years of maximum growth in the federal republic of germany - between and - the energy input of industry per unit of production declined by % demonstrates the feasibility of economies. in the future savings will be possible in private households and in transport in particular. saving energy means first of all investing. the industrialized countries must use the impetus of the energy crisis for a new thrust forward in the field of innovation. saving energy is one side of the coin. the other side is the opening-up of new sources of energy. the developing countries are offering special opportunities for finding additional traditional and novel sources of energy. the existing potentialities in this field open favourable prospects for the long term. the oil-importing developing countries possess % of the so far proven oil deposits. the world bank estimates however that they possess up to % of all exploitable reserves. the difference is explained by arrears of exploration as is shown by the fact that the well-drilling density in potentially oil-bearing areas in the industrialized countries is times higher than in the oil-importing developing countries. inadequate use is also made of the wealth of hydraulic power in the third world. of the technical hydro-electric power potential only about % is being utilized in africa, % in latin america and % in asia. installations for the use of solar energy, the force of the wind, terrestrial heat and biomass are also no technical gimcracks. too little use is made of coal and lignite deposits. such deposits could be opened up in developing countries where they are known to exist. nuclear energy is indispensable. even if many developing countries do not yet offer the requisite technical and safety conditions to consider its use in the foreseeable future in every country, it will lessen the world-wide pressure of the demand for oil wherever it is put to use. the energy generation in developing countries will be assisted this year with some four billion dollars of public bilateral and multilateral funds. the federal republic of germany alone is supporting energy projects in with about dm mn of public development aid commitments. this is more than twice as much as three years ago. the energy resources of the earth are immense. but to open up new sources of energy takes time and requires a considerable amount of finance. faced with a rapidly widening gap between oil prices and their own payments potential, many developing countries no longer possess the necessary means for using their opportunities and bridging a period of scarcity with their own resources. new avenues for recycling needed a few opec countries will accumulate annual current account surpluses greatly in excess of $ bn. if the world economy could be regarded as one entity, this would represent a high world savings ratio, and if this were matched by corresponding investments, it would open up more opportunities than risks. as however no extra demand will be generated by the opec surpluses which have been taken out of the circular flow in the industrialized and oil-importing developing countries, the oil price problem has not only a much-discussed inflationary aspect but a deflationary aspect to which so far little attention has been paid. the world is not short of capital or technical know- how, of raw materials or energy resources or labour. what causes so much trouble is the problem of the intereconomics, july/august energypolicy productive investment of the oil funds, their combination with the other production factors in such a way as to facilitate the required structural adjustments which seem almost unattainable, especially in the developing countries. nevertheless the recycling problem has never yet been put on the agenda of any of the big international conferences. the surpluses of the oil countries must be turned to use by being lent to borrowers whose urgent problems they would help to solve. but the oil countries must at the same time be given an incentive to go on selling oil instead of leaving it in the ground because they expect its value to rise further. it is only reasonable to spread the oil extraction in the oil countries over a longer period. the alternative however is not between either leaving the oil in the ground or bringing it up at an extra-fast rate. neither we nor future generations wish to sit in the dark. what is wanted is a sensible middle course and the evolvement of forms of investment which safeguard and enhance the value of the oil monies. opportunities for profitable investment of the surpluses exist in the form of loans and other capital investments in industrialized countries. but these are not sufficient. it is important that the developing countries are brought into the recycling process. as has been explained earlier, this will be significantly more difficult in the future. the role of the imf more use has to be made of the international monetary fund and other multilateral financing institutions as recycling intermediaries. in the future the developing countries will have to cover a larger part of their additional borrowing requirements with the imf and, as far as can be foreseen, also with the world bank than they have done hitherto. the monetary fund is on the right road. it is already much more involved in the financing process than in the last two years. but the monetary fund must be recognized by the developing countries as not only a source of finance but a helpmate in ineluctable adjustment processes. this is also the object of the structural adjustment loans which the world bank is to accord to the developing countries in the future. all the parties concerned will have to strive for a better combination of what is economically desirable and politically practicable than was achieved in the past. this means amongst other things that more consideration will have to be given to the social and political repercussions of intereconomics, july/august adjustment measures without impairing the fundamental aim of achieving a better balance between balance of payments financing and economic policies which eliminate the causes of the deficits. the bilateral development aid will also have to be directed towards this aim in the next few years. increased resource transfer there is a greater need than ever before for increased resource transfers to the developing countries even though many industrialized countries are facing problems of their own which render such transfers also more difficult than ever. the federal republic has markedly increased its funds for bilateral and multilateral development aid despite a difficult financial situation. in the german development aid reached a record level of over dm bn, i. e., about twice as much as two years earlier. its share of the gross national product rose from . % in to . % in . the federal republic is contributing a larger share to the capital increase for the world bank and the sixth replenishment of the international development association (ida) which is of special importance for the poorest developing countries. in the coming years the german aid will increase at least twice as fast as the expenditure of the federal government as a whole. the eastern bloc does little in the third world that is not intrinsic to its military engagement there, and there is unfortunately little reason to expect it to adopt a different attitude in the future. public development aid will however continue to be of limited proportions. the high oil prices - which are after all also transfers to the third world, albeit mostly to its more prosperous part - do not make it easier to increase the development aid in favour of the poorer countries. with the current account deficits of third world countries - overwhelmingly due to oil imports - estimated for at $ b n , all the public development aid contributions of the industrialized countries of the west, which together amount to about $ bn, are not nearly enough even to maintain the status quo in the third world, to say nothing of advancing it. greater commitments by opec states development aid by the industrialized countries and increased support by the imf and the world bank are needed but do not suffice for a solution of the external economic problems of the developing countries. a much stronger direct commitment in the developing energypolicy countries on the part of the opec states is indispensable. this applies to the public development aid of the surplus states which at about $ bn already accounts for more than one-fifth of the development aid contributions of all the donor countries but has hitherto been concentrated on a few islamic developing countries. above all however it applies to private capital investments in the third world. why should not, for instance, a german company undertake an investment in the third world together with a saudi-arabian financier? why should joint german-arab ventures not be launched in the third world? bureaucratic obstructions keep many investors from engagements in developing countries which also often lack the requisite infrastructure. many of the obstacles in developing countries are home-made. in many developing countries the incalculable hazards from state regulations and red-tape weigh much more heavily than the actual commercial risks. this situation is not conducive to franc, petrodollar, mark or riyal investments by profit-motivated investors. it is the concern of the developing countries to determine the overall conditions for private business activities by foreign enterprises in their country. in doing so they must respect the interests of their partners in private commercial cooperation if investments are to be facilitated. this entails adherence to the principles of international law in regard to expropriation, nationalization and compensation for such acts. they must guarantee the free transfer of capital and set out their economic, monetary and social policies in such unequivocal terms that foreign firms can comply with these policies. agreements between transnational enterprises and the developing countries must be fair. they last longer if they are. the federal republic is therefore cooperating actively in the efforts under united nations auspices to lay down clear rules of conduct for the transnationals as well as for their home and host countries. such rules of conduct are certainly also in the long-term interest of private business. improved conditions for private investments cannot eliminate the risks inherent in civil wars or political upheavals. thought should therefore be given to ways and means by which the international community can lessen or exclude the risk to capital investors. proposals pointing in this direction have been made in the discussion by economists: an international institution could for instance offer to the oil countries securities with a nominal rate of interest which would have to be above the annual rate of price increase of industrial products. the oil countries would be enabled to invest their surpluses at a guaranteed real rate of interest. a part of thus deposited oil monies could be used for credits on favourable terms to oil-importing developing countries. such a guarantee policy might prove advantageous even if involving manifest losses because the industrialized countries could in return obtain regular oil supplies at by and large predictable prices. when hundreds of billions of dollars have to be recycled it may in any case be asked whether an international risk-bearing community of industrialized countries would not ultimately prove more worthwhile, even if it incurs losses, than the alternative open to some opec states: they can leave their oil in the ground instead of piling up more investment-seeking surpluses. being the interested parties, the industrialized and the developing countries must ask themselves whether a useful purpose would be served by submitting an offer of this kind to the oil countries. the rich oil countries have various options open to them. they can wait. the others have to act. the situation brooks no delay. the ecological situation has also been aggravated by excessive use of wood and manure as energy sources in the third world. the catchword of "the other energy crisis" offers an accurate description. a time-bomb with a highly-explosive mixture of famine and population growth is ticking away alongside the energy crisis. a common responsibility how to supply mankind with energy is not yet a question of limited resources. it is a question posed by our limited ability to make sensible orderly arrangements and to harmonize divergent interests. a great deal has already been said about the eighties and their tasks - more than we can possibly know but less than we ought to know. it is evident however that we live in an interdependent world economy with increasing mutual dependences. the peace of the world and the security and progress of the western democracies are as vulnerable to economic and monetary upheavals in the world as to military challenges. our world-political system is a pluralist one in which the influence even of the two superpowers is limited. the only sensible solution is international cooperation, peaceful harmonization of interests between east and west and between south and north. intereconomics, july/august the antimalarial amodiaquine causes autophagic-lysosomal and proliferative blockade sensitizing huma full terms & conditions of access and use can be found at https://www.tandfonline.com/action/journalinformation?journalcode=kaup autophagy issn: - (print) - (online) journal homepage: https://www.tandfonline.com/loi/kaup the antimalarial amodiaquine causes autophagic- lysosomal and proliferative blockade sensitizing human melanoma cells to starvation- and chemotherapy-induced cell death shuxi qiao, shasha tao, montserrat rojo de la vega, sophia l park, amanda a vonderfecht, suesan l jacobs, donna d zhang & georg t wondrak to cite this article: shuxi qiao, shasha tao, montserrat rojo de la vega, sophia l park, amanda a vonderfecht, suesan l jacobs, donna d zhang & georg t wondrak ( ) the antimalarial amodiaquine causes autophagic-lysosomal and proliferative blockade sensitizing human melanoma cells to starvation- and chemotherapy-induced cell death, autophagy, : , - , doi: . /auto. to link to this article: https://doi.org/ . /auto. published online: oct . submit your article to this journal article views: view related articles citing articles: view citing articles https://www.tandfonline.com/action/journalinformation?journalcode=kaup https://www.tandfonline.com/loi/kaup https://www.tandfonline.com/action/showcitformats?doi= . /auto. https://doi.org/ . /auto. https://www.tandfonline.com/action/authorsubmission?journalcode=kaup &show=instructions https://www.tandfonline.com/action/authorsubmission?journalcode=kaup &show=instructions https://www.tandfonline.com/doi/mlt/ . /auto. https://www.tandfonline.com/doi/mlt/ . /auto. https://www.tandfonline.com/doi/citedby/ . /auto. #tabmodule https://www.tandfonline.com/doi/citedby/ . /auto. #tabmodule © l an de s b io sc ie nc e. d o no t d is tr ib ut e. basic research paper www.landesbioscience.com autophagy autophagy : , – ; december ; © landes bioscience basic research paper introduction autophagy is an evolutionarily conserved, intracellular cata- bolic pathway that serves survival functions by maintaining cellular homeostasis under adverse conditions such as nutrient deprivation and accumulation of misfolded proteins or damaged organelles. - dysregulation of autophagy has been implicated in a broad range of human pathologies including neurodegeneration and cancer, , and pathological alterations of autophagic-lyso- somal function can also occur in response to exposure to environ- mental toxicants such as arsenic and solar uv radiation. - recent evidence suggests that cancer cells may harness autophagic path- ways as an adaptation to conditions associated with the tumor microenvironment including increased levels of oxidative and *correspondence to: georg t wondrak; email: wondrak@pharmacy.arizona.edu submitted: / / ; revised: / / ; accepted: / / http://dx.doi.org/ . /auto. the antimalarial amodiaquine causes autophagic- lysosomal and proliferative blockade sensitizing human melanoma cells to starvation- and chemotherapy-induced cell death shuxi qiao, shasha tao, montserrat rojo de la vega, sophia l park, amanda a vonderfecht, suesan l jacobs, donna d zhang, and georg t wondrak* department of pharmacology and toxicology; college of pharmacy and arizona cancer center; university of arizona; tucson, az usa keywords: malignant melanoma, amodiaquine, chloroquine, autophagy, lysosome, cathepsin, e f , cdkn a abbreviations: actb, actin, beta; aq, amodiaquine; anx a , annexin av; bafa, bafilomycin a ; becn , beclin , autophagy related; ccnd , cyclin d ; cdkn a, cyclin-dependent kinase inhibitor a (p , cip ); cddp, cis- dichloro-diamine-platinum (ii); cq, chloroquine; ctsb, cathepsin b; ctsd, cathepsin d, ctsl, cathepsin l; ddit , dna-damage-inducible transcript ; doxo, doxorubicin; e f , e f transcription factor ; egr , early growth response ; gfp, green fluorescent protein; hbss, hank’s balanced salt solution; hspa a, heat shock kda pro- tein a; jc- , , ́ , , ́ -tetrachloro- , ́ , , -́tetraethylbenzimidazolyl-carbocyanine iodide; lamp , lysosomal-asso- ciated membrane protein ; pi, propidium iodide; rb , retinoblastoma ; rfp, red fluorescent protein; sds-page, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; snca, synuclein, alpha (non a component of amyloid precursor); sqstm , sequestosome /p ; tem, transmission electron microscopy; tp , tumor protein pharmacological inhibition of autophagic-lysosomal function has recently emerged as a promising strategy for che- motherapeutic intervention targeting cancer cells. repurposing approved and abandoned non-oncological drugs is an alternative approach to the identification and development of anticancer therapeutics, and antimalarials that target autophagic-lysosomal functions have recently attracted considerable attention as candidates for oncological repurpos- ing. since cumulative research suggests that dependence on autophagy represents a specific vulnerability of malignant melanoma cells, we screened a focused compound library of antimalarials for antimelanoma activity. here we report for the first time that amodiaquine (aq), a clinical -aminoquinoline antimalarial with unexplored cancer-directed chemo- therapeutic potential, causes autophagic-lysosomal and proliferative blockade in melanoma cells that surpasses that of its parent compound chloroquine. monitoring an established set of protein markers (lamp , lc -ii, sqstm ) and cell ultrastructural changes detected by electron microscopy, we observed that aq treatment caused autophagic-lysosomal blockade in malignant a melanoma cells, a finding substantiated by detection of rapid inactivation of lysosomal cathepsins (ctsb, ctsl, ctsd). aq-treatment was associated with early induction of energy crisis (atp depletion) and sensitized melanoma cells to either starvation- or chemotherapeutic agent-induced cell death. aq displayed potent anti- proliferative effects, and gene expression array analysis revealed changes at the mrna (cdkn a, e f ) and protein level (tp , cdkn a, ccnd , phospho-rb [ser ]/[ser / ], e f ) consistent with the observed proliferative blockade in s-phase. taken together, our data suggest that the clinical antimalarial aq is a promising candidate for repurposing efforts that aim at targeting autophagic-lysosomal function and proliferative control in malignant melanoma cells. © l an de s b io sc ie nc e. d o no t d is tr ib ut e. autophagy volume issue proteotoxic stress, hypoxia, and energy crisis. , , autophagy also occurs in response to exposure to major classes of chemo- therapeutic agents (e.g., cisplatin and doxorubicin [doxo]), a process thought to contribute to cancer cell chemoresistance. , , therefore, pharmacological inhibition of autophagic-lysosomal function has recently emerged as a promising strategy for thera- peutic intervention that may preferentially target cancer cells without compromising viability of normal cells. , , , - repurposing approved and abandoned non-oncological drugs is an alternative developmental strategy for the identification of anticancer therapeutics, and antimalarials that potentially under- mine autophagic-lysosomal functions have recently attracted considerable attention as promising candidates for oncologi- cal repurposing. , , since all autophagic pathways (including macroautophagy, microphagy, and chaperone-mediated auto- phagy) converge on lysosomal fusion followed by enzymatic degradation irrespective of the specific mechanism employed for cargo selection and trafficking, members of the lysosomotropic -aminoquinoline (e.g., primaquine, pamaquine), -amino- quinoline (e.g., chloroquine [cq], hydroxychloroquine), and quinoline (e.g., mefloquine) classes of antimalarials that disrupt lysosomal ph control and function have been examined as exper- imental (preclinical) and investigational (clinical) cancer thera- peutics. , , - indeed, cq and hydroxychloroquine are currently undergoing evaluation in numerous oncological clinical trials that examine potentiation of therapeutic efficacy by combining cytotoxic chemotherapeutics with autophagic-lysosomal antago- nists. however, limited efficacy and systemic toxicity associated with these prototype agents create an urgent need for the iden- tification and development of improved therapeutics that target autophagic-lysosomal function in cancer cells. , , melanoma is a malignant melanocyte-derived tumor caus- ing the majority of deaths attributed to skin cancer. , despite recent progress in the design of targeted therapies such as the v e-mutation directed br af-inhibitor vemurafenib, efficacy of chemotherapeutic intervention directed against the meta- static stage of the disease remains limited, and identification and development of improved molecular agents targeting malignant melanoma cells remain important goals of current research. cumulative evidence suggests the involvement of autophagic dysregulation in melanomagenesis, and the emerging role of autophagy as a prognostic factor and therapeutic target in mela- noma has been substantiated recently. , - consistent with this hypothesis, the efficacy of cisplatin chemotherapeutic interven- tion targeting melanoma can be potentiated by inhibitors of auto- phagy, and leucine deprivation combined with pharmacological suppression of autophagy shows therapeutic efficacy in a murine xenograft model of the human disease. , recently, we have screened a compound library of clinical antimalarials for antimelanoma activity, identifying the endo- peroxide-based redox antimalarial dihydroartemisinin and other members of the artemisinin-class as potent inducers of melanoma cell apoptosis. , as part of our screening efforts we also focused on amodiaquine (aq; -[( -chloroquinolin- -yl)amino]- - [(diethylamino)methyl]phenol cas#: - - ; chemical struc- ture: fig. a), a member of the lysosomotropic -aminoquinoline class of antimalarials used worldwide in combination with arte- misinin-drugs. , aq displays potent plasmodium-directed activity that may surpass that of its parent compound cq, but its potential cancer cell-directed activities have remained unexplored. here we report for the first time that aq targets malignant mela- noma cells with pronounced induction of autophagic-lysosomal and proliferative blockade causing sensitization to starvation- and chemotherapeutic-induced cell death. results amodiaquine causes morphological alterations in human malignant a melanoma cells consistent with lysosomal impairment first, aq-induced morphological changes were examined in human a melanoma cells using light microscopy (fig. b) and transmission electron microscopy (tem; fig. c and d). visualization by light microscopy revealed a distinct accumula- tion of vacuole structures with predominantly perinuclear local- ization within h aq exposure, not observed in untreated control cells (fig. b). subsequent tem analysis (magnifica- tion , and , fold) (fig. c and d) of aq-exposed melanoma cells indicated the pronounced formation of large ( . – µm diameter), multivesicular single membrane-enclosed structures containing electron-dense osmiophilic inclusions, an observation indicative of lysosomal expansion and lipofuscin accumulation, not observed in untreated control cells. , , in contrast, no accumulation of double-membrane-enclosed small vesicles that would be indicative of increased autophagosome formation was observed in response to aq treatment. time- course analysis demonstrated that formation of osmiophilic, multivesicular structures in aq-treated melanoma cells could be observed within h, reaching a plateau at - to h exposure time (fig. d). amodiaquine causes autophagic-lysosomal blockade in human malignant a melanoma cells next, immunoblot analysis demonstrated aq-induced accu- mulation of lysosomal-associated membrane protein (lamp ) indicative of lysosomal expansion as already suggested by tem visualization (fig. a). , in parallel, massive accumulation of lc -ii occurred in response to aq exposure in a dose-depen- dent manner and could be observed at concentrations as low as µm. lc , the mammalian homolog of yeast atg , is an essential factor for autophagosome formation that relocalizes to and par- ticipates in the formation of the autophagosomal membrane after c-terminal proteolytic processing and posttranslational phos- pholipid-conjugation. therefore, after relocalization of lc -i to newly formed vesicles a more rapidly migrating lipidated form (lc -ii) is detectable by sds-page (fig. a). strikingly, pronounced accumulation of sqstm /p (sequestosome ), an autophagic cargo receptor and substrate that undergoes depletion upon autophagy induction, occurred at the protein level. , - similar accumulation occurred with snca (α-synuclein), another autophagic substrate protein that accumulates as a consequence of blocked autophagic-lysosomal flux. , , in contrast, becn (beclin ), a critical component of © l an de s b io sc ie nc e. d o no t d is tr ib ut e. www.landesbioscience.com autophagy the class iii ptdins -kinase complex involved in autophagosome formation, remained unchanged at the protein (fig. a) and mrna (data not shown) levels. since it has been shown ear- lier that the aminophenol-moiety contained in aq (but not cq ) can cause protein modification (haptenization) we also explored the possibility that aq may cause covalent protein adduction in malignant melanoma cells. , using a monoclonal antibody ( d ) employed for the immunodetection of aq-adducted plasma protein in malaria patients, we detected the accumula- tion of aq-modified proteins ( - to -kda molecular mass range) in melanoma cells exposed to aq ( µm, h; fig. a). however, identity of adducted target proteins and causative involvement of protein adduction in aq-induced autophagic- lysosomal impairment remain undefined at this point. consistent with tem-visualization of osmiophilic vesicles (fig. c and d), a cells displayed increased lipofuscin accumulation as evidenced by flow cytometric detection of autofluorescent intracellular material that formed upon pro- longed aq exposure ( – h; fig. b), changes indicative of impaired autophagic-lysosomal function as described before. , , importantly, similar changes affecting lamp , lc -ii, and sqstm were observed in human g metastatic melanoma cells exposed to low micromolar concentrations of aq (fig. c). after demonstrating accumulation of autophagy substrates and lysosomal marker proteins (lc -ii, sqstm , snca, lamp ) we gathered further mechanistic evidence in support of aq-induced autophagic-lysosomal blockade by monitoring lc puncta formation in a melanoma cells. to this end, cells transfected with a tandem reporter construct (rfp-gfp-lc ) were exposed to aq ( µm, h) followed by assessment of gfp-lc and rfp-lc puncta colocalization (fig. d). , gfp-fluorescence is quenched in acidic environments (such as that encountered in the autolysosome), whereas rfp is more stable under acidic conditions. therefore, colocalization of both gfp and rfp fluorescence (yellow puncta in a merged image) indicates either autophagosomal localization (upstream of fusion with the acidic lysosome) or autolysosomal localization (i.e., in autolysosomes with disrupted acidification). indeed, exposure to figure  . amodiaquine-induced morphological changes in human malignant a melanoma cells. (a) chemical structure of aq. (b) cells were exposed to aq ( µm, h) or remained untreated (control). visualization by light microscopy (upper panel: control; bottom panel: aq). (c) transmission elec- tron microscopy. left: control; middle: aq ( µm, h; , -fold direct magnification); right: aq ( µm, h; , -fold direct magnification). (d) transmission electron microscopy; time-course analysis (aq, µm, – h; , -fold direct magnification); right panel: aq ( µm, h; , -fold direct magnification); m, mitochondrion; n, nucleus; v, single membrane-enclosed osmiophilic multivesicles. © l an de s b io sc ie nc e. d o no t d is tr ib ut e. autophagy volume issue aq caused pronounced formation of lc puncta that displayed both green and red fluorescence intensity producing a yellow overlay, consistent with accumulation of autolysosomes that dis- play impaired acidification. furthermore, control cells exposed to bafilomycin a (bafa, a standard inhibitor of lysosomal acidi- fication and substrate degradation that impairs autophagosome- lysosome fusion ) displayed an lc -fluorescence pattern (puncta formation with yellow overlay) that mimicked that induced by aq treatment. moreover, consistent with the published litera- ture on lysosomotropic agents, fluorescence imaging using the ph sensitive lysosomal probe lysosensor™ green dnd- revealed a similar pattern of impaired lysosomal acidification resulting in rapid loss of ph control in response to treatment with either bafa or aq (data not shown). in order to gain further insight into the mecha- nism of aq-induced autophagic-lysosomal alterations, an lc turnover assay employing bafa cotreatment was performed (fig. a). in this assay, we assessed aq-induced lc -ii accumulation in the pres- ence or absence of the lysosomal inhibitor bafa. as observed above (fig. a), aq treatment caused an increase of lc -ii levels within – h exposure time. importantly, if aq exposure occurred in the presence of bafa, aq-induced upregulation of lc -ii levels was not potentiated, an observation most consistent with an autophagic-lysosomal blockade of lc -ii deg- radation at the autolysosomal level. in support of a direct impairment of lysosomal function by aq treatment, pronounced inhibition of cathepsin enzymatic activity was detected in a cells that occurred in a dose- and time-dependent manner ( – μm, – h; fig. b). aq treatment caused pronounced enzyme inactivation of both cys- teine- (ctsb [cathepsin b] and ctsl [cathepsin l]) and aspartate-dependent (ctsd [cathepsin d]) cathepsins, consistent with a global impairment of lysosomal function by this lysosomotropic -ami- noquinoline-derivative. remarkably, within only h aq exposure time, ctsb enzymatic activity was already reduced by almost % diminishing further over the next h, with only approximately % residual activity detectable. this inhibitory effect is in accordance with the documented activity of lyso- somotropic antimalarials (including cq and aq ) that disrupt the acidic food vacuole of the plasmo- dium parasite and also compromise mammalian cell lysosomal function through alkalinization and membrane destabilization. , interestingly, recent evidence indicates that lysosomal cathepsins includ- ing ctsb and ctsd are involved in lc -ii proteo- lytic turnover and that pharmacological inhibition of ctsb causes accumulation of lc -ii, support- ing the hypothesis that cathepsin inactivation is the causative factor underlying massive accumulation of lc -ii as observed in aq-exposed a melanoma cells (fig. a). , importantly, inhibition of ctsb and ctsl activity by aq treatment was also observable in other melanoma cell lines including g (fig. c). however, ctsd activity remained undiminished in g cells exposed to aq, indicating a differ- ential sensitivity of cysteine-dependent (ctsb/l) vs. aspartate- dependent (ctsd) cathepsins in g cells, a phenomenon that remains poorly understood at this time. aq induces energy crisis and sensitizes malignant mela- noma cells to starvation- and chemotherapeutic-induced death next, we examined aq modulation of melanoma cell vul- nerability to starvation and chemotherapeutic intervention (fig. ). in untreated control cells exposed to hank’s balanced figure  . amodiaquine-induced autophagic-lysosomal alterations in human malig- nant melanoma cells. (a) after exposure of a cells to aq ( – μm; h), modu- lation of autophagic-lysosomal proteins (lc -i/-ii, sqstm , becn , lamp , snca) was detected by immunoblot analysis (loading control: actb). protein adduction of unidentified target proteins was detected using an aq-directed monoclonal antibody. (b) cellular autofluorescence as detected by flow cytometric analysis. after exposure to aq ( μm, – h), autofluorescence intensity of a cells was quantified by flow cytometry (left panel: histogram representative of three similar repeats; right panel: bar graph summarizing data from three independent repeats [n = , mean ± s.d.; p < . ]). (c) aq-induced changes as examined in g metastatic melanoma cells ( – μm, h) detected as in (a). (d) autophagic flux analysis using the rfp-gfp-lc puncta formation assay. after transfection using a tandem reporter construct (rfp-gfp-lc ) cells were exposed to aq ( µm, h), and colocalization of gfp-lc and rfp-lc puncta was examined using fluorescence microscopy. dual fluorophore-labeled lc transfectants appear yellow upon colocalization. a similar fluorescence pattern (accumulation of yellow fluorescent puncta) was observed in response to the lysosomal proton pump inhibitor bafa ( nm, ≤ h). © l an de s b io sc ie nc e. d o no t d is tr ib ut e. www.landesbioscience.com autophagy salt solution (hbss, causing serum and amino acid starvation) for up to h, pronounced depletion of the autophagy substrate sqstm was observed, an observation in accordance with the established stimulatory effect of starvation on autophagic activ- ity (fig. a, upper panel). this starvation-induced depletion of sqstm was completely suppressed by aq co-treatment suggesting that aq-blockade of autophagic-lysosomal function interferes with star- vation-induced degradation of autophagy substrates (fig. a, bottom panel). we also observed that aq-exposed melanoma cells displayed early energy crisis as evident from sig- nificant depletion of cellular total atp levels that occurred as early as within h treatment (fig. b), consistent with earlier reports indicating that ami- noquinoline-antimalarials may compromise mito- chondrial function and transmembrane potential. , consistent with an induction of energy crisis due to impairment of mitochondrial function, - flow cyto- metric analysis using the sensor dye jc- revealed a moderate yet significant decrease in mitochondrial transmembrane potential (Δψm) observable at early time points ( µm, h; fig. c: top panels: bivari- ate analysis), where aq treatment diminished jc- red fluorescence intensity (indicative of fully polar- ized mitochondria) by approximately . % (con- trol: . ± . ; aq: . ± . ; n = ; fig. c; bottom panel). importantly, even upon lon- ger exposure to aq no further reduction in Δψm was observed (data not shown), and cells maintained full viability ( µm aq, h; fig. d). even though neither starvation nor extended exposure to aq ( µm, h) diminished cellular viability if adminis- tered separately (fig. d), pronounced induction of cell death occurred in response to combination treatment (starvation plus aq exposure). these data strongly suggest that aq compromises mitochondrial function and blocks starvation-induced autophagic- lysosomal adaptations thereby sensitizing melanoma cells to the cytotoxic metabolic stress imposed by pro- longed starvation. cumulative evidence suggests a role of autophagic dysregulation in cancer cell resistance to chemotherapeutic agents. , , based on our observation that aq is a potent inhibi- tor of autophagic-lysosomal function we therefore tested the hypothesis that aq may sensitize melanoma cells to the cytotoxic action of standard chemotherapeutics. indeed, we observed that cytotoxicity of specific chemotherapeutics (cddp, doxo) was strongly potentiated upon co-exposure with aq employed at con- centrations that do not impair viability of a melanoma cells if used as single treatment (fig. e and f). specifically, when cells were exposed to the combined action of cddp and aq, the frac- tion of dead cells increased from approximately . % (cddp only) to over . % (cddp plus aq; fig. e). moreover, when cells were exposed to the combined action of doxo and aq, the figure  . amodiaquine-induced loss of cathepsin enzymatic activity in human malig- nant melanoma cells. (a) immunoblot detection of lc -ii in a cells left untreated (lane ), exposed to bafa only ( nm; or h; lanes , ), or exposed to aq ( µm) in the absence (lanes and ) or presence of bafa (lanes and ). (b and c) loss of cathepsin-specific enzymatic activity in a (b) and g cells (c) exposed to aq ( – μm, ≤ h) was detected using a fluorimetric assay. top panels: ctsb, dose response ( h); middle panels: ctsb, time course ( µm); bottom panels: ctsd and ctsl, dose response ( h). treatment with the ctsb/l inhibitor ca me ( μm) served as a positive control (n = , mean ± s.d.; p < . ). fraction of dead cells increased from approximately . % (doxo only) to over . % (doxo plus aq; fig. f). gene expression array analysis reveals an aq-induced pro- liferative blockade in a melanoma cells to gain further mechanistic insight into the molecular events underlying antimelanoma activity of aq, we performed gene expression array analysis. to this end, modulation of gene expres- sion in response to aq exposure ( µm, h), vs. control was assessed using a pcr-based expression array system. out of cell stress and autophagy-related genes contained on the com- bined array, genes displayed aq-induced expression changes at the mrna level by at least -fold over untreated control cells (fig. a and b). strikingly, aq treatment caused pronounced © l an de s b io sc ie nc e. d o no t d is tr ib ut e. autophagy volume issue modulation of gene expression antagonizing cell cycle progres- sion. e f , the gene encoding the transcription factor and master regulator of g /s cell cycle transition, e f , displayed the highest negative expression differential ( . -fold downregulation) elicited by aq. conversely, expression of cdkn a, the tp -controlled gene encoding cdkn a (cyclin-dependent kinase inhibitor a [p , cip ]), a negative regulator of cell cycle progression caus- ing g , g , or s-phase arrest, was upregulated significantly ( . -fold). subsequent immunoblot analysis confirmed e f and cdkn a expression changes at the protein level (e f , cdkn a; fig. a and b), and a dose response relationship of cdkn a mrna upregulation was established (fig. c). aq treatment also caused negative modulation of a broad array of genes encoding heat shock response proteins (hspa , hspa a, hsp aa , hspca, hspa , hspa l, dnaja , cryab), and a dose response relationship of hspa a mrna downregulation was established (fig. c). aq-induced suppres- sion of heat shock response-encoding genes was also observed at the protein level (hspa a, hsp aa ; fig. a and b). pharmacological downregulation of heat shock response gene expression is expected to increase proteotoxic stress, particularly in cancer cells constitutively exposed to a high unfolded protein burden. , indeed, consistent with the suppression of heat shock response gene expression by aq, array analysis indicated tran- scriptional upregulation of the er stress response gene ddit ( . fold) encoding a transcription factor (also known as chop/ gadd ), a common marker of proteotoxic stress. in addition, upregulation of other genes responsive to vari- ous types of cytotoxic stress was observed in aq-treated a cells including gadd a (encoding growth arrest and dna- damage-inducible, α, a tp -regulated dna damage induc- ible stress sensor), egr (encoding early growth response , an oxidative stress-sensitive transcription factor), and tp (encoding tumor protein p , a genotoxic stress- and general stress-responsive tumor suppressor and transcription factor). importantly, pronounced tp upregulation was also observed at the protein level (tp ; fig. a), and upregulation of the tp target gene gdf (encoding growth differentiation factor figure  . amodiaquine causes rapid atp depletion and sensitization to starvation- and chemotherapeutic-induced cell death. (a) aq modulation of starvation-induced sqstm depletion. a melanoma cells were cultured in hbss in the presence or absence of aq ( μm, – h). protein levels of sqstm were determined by immunoblot analysis using actb as a loading control. (b) early cellular atp depletion induced by aq exposure ( and µm, ≤ h). data are expressed as % of untreated controls (mean ± s.d.; n = ). (c) alteration of mitochondrial transmembrane potential (Δψm) in response to aq ( µm, h) as assessed by bivariate flow cytometric analysis of jc- -stained cells. the upper two panels display one representative experiment of three similar repeats, and numbers indicate cells with impaired Δψm (in percent of total gated cells) detected outside the circle (mean ± sd, n = ). lower panel displays aq-induced alteration of jc- red fluorescence (polarized mitochondria, detector fl- ; representative experiment of similar repeats). (d) cell viability as determined by flow cytometric analysis of anxa -fitc/pi staining in cells cultured in hbss or standard medium in the presence or absence of aq ( µm, h). the numbers indicate viable (anxa -/pi-) in percent of total gated cells (mean ± s.d.; n = ). (e and f) chemosensitization by aq was examined in a cells exposed to the combined action of cisplatin (cppd, µm; h [d]) or doxorubicin (doxo, nm; h; [e]) with or without aq ( µm, h). cell viability was analyzed by flow cytometry. the bar graph summarizes data from three repeats (n = , mean ± s.d.). data were analyzed employing one-way analysis of variance (anova) with tukey’s post hoc test. means without a common letter differ from each other (p < . ). © l an de s b io sc ie nc e. d o no t d is tr ib ut e. www.landesbioscience.com autophagy figure  . gene expression array analysis performed in a melanoma cells exposed to amodiaquine. gene expression in response to aq ( µm, h) was analyzed using the human autophagy rt profilertm and the human stress and toxicity rt profilertm pcr expression arrays. (a) the scatter blot depicts differential gene expression (aq vs. untreated control). upper and lower lines: cut-off indicating -fold up- or downregulated expression, respectively. arrays were performed in independent repeats and analyzed using the two-sided student t test. (b) the table summarizes expression changes by at least -fold (p < . ). © l an de s b io sc ie nc e. d o no t d is tr ib ut e. autophagy volume issue , a member of the transforming growth factor β superfamily) was observed. finally, aq treatment also caused expression changes affecting genes involved in inflammatory signaling (il encoding interleukin , [interferon β ]; csf encoding colony stimulating factor [granulocyte-macrophage]) and autophagic regulation (autophagy-related genes atg a, atg b, atg d; gabarapl , bnip ), but none of these changes were substan- tiated at the protein level. antiproliferative activity of aq is associated with s phase cell cycle arrest and modulation of g /s cell cycle regulators flow cytometric analysis revealed that aq exposure imposed pronounced alterations in cell cycle distribution. specifically, continuous exposure of a cells to aq ( μm, h) caused a statistically significant increase in s-phase fraction that was accompanied by a decrease of cells in g and g /m phase (fig. d). specifically, the fraction of cells in s phase increased from approximately % to % upon treatment with aq ( µm, h), accompanied by pronounced depletion of cells in g and g /m. further experiments employing a panel of cul- tured human melanoma cell lines (a , g , lox) con- firmed that aq caused pronounced antiproliferative activity at figure  . amodiaquine treatment modulates cell cycle regulators (cdkn a, rb [ser ; ser / ], ccnd , e f ) causing inhibition of proliferation and s phase cell cycle arrest. (a) immunoblot detection of aq-induced (≤ µm; h) expression changes affecting heat shock proteins and major cell cycle regulators in a cells (loading control: actb). (b) immunoblot analysis of aq-induced expression changes in g melanoma cells treated as in (a). (c) cdkn a and hspa a mrna levels in a cells exposed to aq ( , , µm; h) were determined by real time rt-pcr analysis (mean ± s.d., n = ). (d) representative histogram depicting cell cycle distribution after treatment with aq ( µm, ≤ h). after treatment for the indicated time periods, cells were stained with pi and analyzed by flow cytometry. the data indicate the percentage of cells in each phase of the cell cycle. the table summarizes results from independent repeat experiments (mean ± sd [n = ]; *p < . ; **p < . ; ***p < . ). (e) dose-response relationship of aq or cq-induced inhibition of proliferation in malignant melanoma cell lines (a , g , lox). after h exposure to increasing concentrations of aq or cq, number of adherent cells on the dish was determined by cell counting and expressed as % of untreated control (means ± s.d.; n = ) © l an de s b io sc ie nc e. d o no t d is tr ib ut e. www.landesbioscience.com autophagy submicromolar concentrations (a : ic = . ± . µm; g : ic = . ± . µm; lox: ic = . ± . µm; mean ± sd, n = ; fig. e). in order to substantiate the molecular changes underlying antiproliferative effects of aq we exam- ined modulation of protein regulators determin- ing g /s transition focusing on those that displayed major aq-induced expression changes as detected by array analysis including tp , cdkn a, and e f (fig. a and b). we also examined ccnd (cyclin d ), phosphorylation status of rb (retinoblastoma ), and myc. immunoblot analysis revealed pronounced upregu- lation of cdkn a protein levels, a potent cyclin-dependent kinase inhibitor that directly inhibits the activity of ccne (cyclin e)-cdk and ccnd-cdk / complexes involved in g /s phase transition and progression. , consistent with the observed dose-dependent upregulation of cdkn a mrna and cdkn a protein levels (fig. ; fig. a and c), upregulation of tp , the transcriptional regulator of cdkn a, was observed at the transcriptional (tp [fig. b]) and protein levels (fig. a). moreover, moderate suppression of ccnd protein levels occurred in response to aq treatment (fig. a). next, we focused on e f , the gene that displayed the most pronounced downregulation at the transcriptional level (fig. a and b). remarkably, aq-suppression of e f expression was con- firmed at the protein level (fig. a). e f is a transcription factor and master regulator of cell proliferation, expressed mainly at late g and g /s transition in all actively proliferating tissues. - we also examined aq modulation of rb , the upstream regulator of e f function. aq treatment caused pronounced reactivation of rb tumor suppressor function by removal of inhibitory phos- phorylations at ser and ser / that interfere with e f sequestration, established sites of posttranslational rb regula- tion at the g /s checkpoint. , since aq modulated a number of major cell cycle regulators (tp , cdkn a, ccnd , e f , rb ) that are involved in functional crosstalk with myc we also examined expression of this master regulator of cell proliferation. however, only moderate downregulation at the protein level was observed (fig. a). importantly, key expression changes induced by aq in a malignant melanoma cells were also observed in metastatic melanoma cells including g cells, where immu- noblot detection confirmed downregulation of heat shock pro- teins (hspa a, hsp aa ) and pronounced upregulation of cdkn a, consistent with the antiproliferative activity of aq (fig. b). in the context of our expression array-guided exploration of aq-induced antimelanoma effects, it should be mentioned that immunoblot detection did not always confirm changes observed at the mrna level. for example, significant downregulation of rpl a mrna (- . fold; encoding s ribosomal protein l a; fig. a and b) was detected by expression array analy- sis but could not be substantiated at the protein level (rpl a; fig. a). therefore, other significant aq-induced changes observed at the mrna level as summarized in figure b await further validation and functional exploration. inhibitory activity of aq on lysosomal function and prolif- eration of melanoma cells surpasses that of cq figure  . comparative analysis of chloroquine- vs. amodia- quine-induced antiproliferative effects. cells were exposed to cq ( µm, h) or remained untreated (control). (a) visualization by transmission electron microscopy [control; cq, ( , -fold direct magnification); cq ( , -fold direct magnification)]; m, mitochondrion; n, nucleus; v, single mem- brane-enclosed osmiophilic multivesicles). (b) autophagic flux analysis using the rfp-gfp-lc puncta formation assay. after transfection using a tandem reporter construct (rfp- gfp-lc ) cells were exposed to aq ( µm, h), and colo- calization of gfp-lc and rfp-lc puncta was examined using fluorescence microscopy. dual fluorophore-labeled lc transfectants appear yellow originating from overlapping green and red fluorescence, consistent with accumulation of autolysosomes displaying impaired acidification. (c) loss of cathepsin enzymatic activity (ctsb, ctsl, ctsd) in a cells exposed to aq (≤ μm, h) detected as described above. (d) comparative potency of aq vs. cq ( µm, h) inhibiting ctsb, ctsl, and ctsd enzymatic activity. (e) aq- vs. cq-induced (≤ µm, h) expression changes at the mrna level in a melanoma cells. (f) immunoblot detection of cq- and aq-induced (≤ µm, h) expression changes of tp protein. (g) immunoblot detection of cq-induced expression changes at the protein level in a melanoma cells. © l an de s b io sc ie nc e. d o no t d is tr ib ut e. autophagy volume issue after investigating the antimelanoma activity of aq, we com- pared chemotherapeutic efficacy between the -aminoquinoline antimalarials aq and its parent compound cq (fig. e; fig. ). first, we compared the potency of anti-proliferative activity displayed by cq vs. aq (fig. e). a comparative dose response relationship analysis performed in a (aq: ic = . ± . µm; cq: ic = . ± . µm), g (aq: ic = . ± . µm; cq: ic = . ± . µm), and lox (aq: ic = . ± . ; cq: ic = . ± . µm; mean ± sd, n = ) melanoma cells identified aq as the superior inhibitor of melanoma cell proliferation among the tested -aminoquinoline antimalarials. next, we examined the induction of autophagic-lysosomal impairment in cq-treated a melanoma cells. we observed that cq-induced morphological changes examined by trans- mission electron microscopy were similar to those induced by aq, including formation of multivesicular, single membrane- enclosed structures containing electron-dense osmiophilic inclu- sions (fig. a). however, morphological changes elicited by cq seemed less pronounced (number and size of multivesicular struc- tures) compared with those induced by aq exposure (fig. c and d vs. fig. a). further analysis revealed cq-induced effects on autophagic-lysosomal function similar to those observed with aq monitoring rfp-gfp-lc puncta formation (fig. b). as observed earlier with aq (fig. d), exposure to cq caused formation of lc puncta that displayed both green and red fluorescence producing a yellow overlay, a finding consistent with the established ability of the lysosomotropic agent cq to induce autophagic-lysosomal blockade through impairment of lysosomal ph-control and function thereby inducing accumu- lation of dysfunctional autolysosomes with colocalization of gfp- and rrp-labeled lc . immunoblot analysis demonstrated cq-induced accumulation of lamp , lc -ii, and sqstm (fig. g), changes similar to aq-induced alterations (fig. a and c). moreover, consistent with prior reports, cq treatment caused a significant inhibition of lysosomal cathepsin activity (ctsb, ctsl, ctsd; fig. c and d). importantly, when cathepsin-directed inhibitory effects were compared between cq and aq ( µm, each), it was observed that aq caused a more pronounced reduction of ctsl and ctsd enzymatic activity, whereas cq and aq were equally effective antagoniz- ing ctsb enzymatic activity (fig. d). differential suppres- sion of lysosomal cathepsin activity by aq vs. cq correlates well with the occurrence of more pronounced morphological changes at the lysosomal level observed in aq-exposed melanoma cells (fig. c and d vs. fig. a). after identifying aq as the superior inhibitor of melanoma cell proliferation among the two tested -aminoquinoline antimalarials (fig. e), we also performed comparative gene expression analysis indicating that cq-induced changes at the mrna level did not match those detected in response to aq (fig. e). specifically, cq treatment failed to change expres- sion of aq-responsive key genes including ddit , cdkn a, gadd a, egr , and e f . consistent with the inferior anti- proliferative potency of cq as compared with aq, subsequent immunoblot analysis demonstrated that even though cq treat- ment caused moderate upregulation of cdkn a protein levels, cq failed to alter protein levels of tp , e f , ccnd , and hspa a, changes observed earlier in response to aq treatment (fig. f and g). indeed, further analysis indicated that cq treat- ment was not associated with the induction of cell cycle arrest (fig. ), an observation strikingly different from aq-induced melanoma cell cycle blockade in s phase (fig. d). discussion pharmacological inhibition of autophagic-lysosomal function has recently emerged as a promising strategy for chemothera- peutic intervention targeting cancer cells. , , , - even though numerous ongoing clinical trials aim at substantiating favorable therapeutic effects of chloroquine and hydroxychloroquine, the limited therapeutic performance of these lysosomotropic -ami- noquinoline derivatives prompted us to explore other promising drug candidates that target autophagic-lysosomal function in cancer cells. in this study we have examined the antimelanoma activity of the antimalarial aq and have observed that in cultured malig- nant melanoma cells aq causes pronounced autophagic-lyso- somal and proliferative blockade that surpasses that of its parent compound cq. aq-induced autophagic-lysosomal antagonism was associated with early inhibition of cathepsin enzymatic activ- ity (ctsb, ctsl, ctsd; fig. b and c) and atp depletion, figure  . analysis of cq-induced alterations of cell cycle distribution. (a) representative histogram depicting cell cycle distribution after treat- ment with cq ( µm, ≤ h). after treatment for the indicated time peri- ods, cells were stained with pi and analyzed by flow cytometry. (b) the data indicate the percentage of cells in each phase of the cell cycle; the table summarizes results from independent repeat experiments (mean ± sd [n = ]). © l an de s b io sc ie nc e. d o no t d is tr ib ut e. www.landesbioscience.com autophagy both detectable within h exposure time (fig. b). aq-imposed impairment of autophagic-lysosomal function was further sub- stantiated by ultrastructural changes observed by electron microscopy (fig. ), gfp-rfp-lc fluorescence imaging (fig. d), and immunoblot detection of specific protein markers (lamp , lc -ii) and autophagy substrates (sqstm , snca; fig. a and c). concerning the mechanism of aq-induced autophagic- lysosomal alterations observed in human melanoma cells, our data are most consistent with a functional blockade imposed by aq at the lysosomal level. , aminoquinoline-antimalarials (including cq and aq ) are established lysosomotropic agents that cause lysosomal disruption with impairment of ph control and inactivation of lysosomal proteases (including cathepsins), a mechanism of action underlying antimalarial activity through disruption of the acidic food vacuole of the parasite. we observed that lysosomal cathepsin activity was impaired rapidly (fig. b and c), and a similar pattern of puncta formation was imposed by the lysosomally-targeted agent bafa or aq as evidenced by rfp-gfp-lc fluorescence (fig. d). moreover, the lc turn- over assay employing bafa did not indicate an upregulation of autophagic flux in response to aq (fig. a), and no accumu- lation of double-membrane structures that would be indicative of increased autophagosome formation was observed by electron microscopy. in contrast, we only detected accumulation of large single membrane-enclosed, multivesicular structures displaying pronounced osmiophilicity, consistent with autolysosomal aggre- gation and accumulation of undigested cargo and lipofuscin in response to aq. in addition to the causation of autophagic-lysosomal altera- tions, we also observed that aq treatment blocked melanoma cell cycle progression in s-phase (fig. d). it is important to note that induction of mitotic arrest in response to lysosomotropic agents has been observed before and was attributed to impaired macroautophagy and tp -mediated effects, , molecular changes that also occur in response to aq treatment (figs. , , and ). our own array analysis revealed modulation of gene expression antagonizing cell cycle progression (cdkn a upreg- ulation, e f downregulation), and immunoblot detection dem- onstrated aq-modulation of tp , cdkn a, e f , ccnd , and phosphorylated rb (ser and / ). indeed, aq dis- played potent antiproliferative effects causing s-phase arrest at submicromolar concentrations (fig. d and e). downregulation of e f expression, the gene displaying the highest aq-induced expression differential at the mrna level (fig. ), is of particu- lar interest since pharmacological e f antagonism has recently emerged as a promising antiproliferative strategy targeting mela- noma. indeed, we observed aq-induced downregulation of e f protein levels at concentrations as low as µm (fig. a). however, the specific mechanisms and upstream events underly- ing aq-induced proliferative blockade as shown here for the first time in human melanoma cells remain to be elucidated. in the context of aq-induced cell cycle arrest that occurs in s-phase rather than in g -phase, it should be mentioned that earlier research has demonstrated that overexpression or pharmacologi- cal upregulation of cdkn a expression, the cell cycle regulator displaying the most pronounced expression changes in response to aq treatment at both the mrna and protein levels (fig. b; fig. a and c), may indeed cause s-phase arrest, , , and phar- macological downregulation of ccnd as well as dephosphory- lation of rb , as observed by us in response to aq treatment, have also been documented in association with s-phase arrest. , our experiments document for the first time that aq treat- ment causes the rapid induction of energy crisis (fig. b), impair- ment of mitochondrial transmembrane potential (fig. c), and the blockade of starvation-induced autophagic-lysosomal adap- tations in malignant melanoma cells (fig. a). this activity may sensitize melanoma cells to the cytotoxic metabolic stress imposed by prolonged starvation, a hypothesis substantiated by our observation that the combined exposure to aq and starva- tion by culture in hbss causes massive melanoma cell death (fig. d). likewise, the observation that aq causes chemosen- sitization to standard chemotherapeutic agents (cddp, doxo; fig. e and f) suggests that combination therapy employing chemotherapeutics together with this clinical antimalarial may provide improved therapeutic efficacy, a hypothesis to be tested in the future. however, the specific mechanism underlying aq-dependent chemosensitization and increased vulnerability to starvation-induced cell death remains undefined and may involve causative factors beyond autophagic-lysosomal modu- lation such as impairment of mitochondrial transmembrane potential, , known to occur in response to treatment with other -aminoquinoline antimalarials and observed here for the first time with aq. , interestingly, it has recently been observed that cq sensitizes breast cancer cells to chemotherapy independent of autophagy, and similar mechanisms may apply to aq-induced sensitization. moreover, massive downregulation of heat shock response gene expression as observed by us at the mrna (e.g., hspa , hspa a, hsp aa ; fig. ; fig. c) and protein level (hspa a, hsp aa ; fig. a and b) may also contrib- ute to aq-induced sensitization to cytotoxic stress, a hypothesis consistent with the established cytoprotective and antiapoptotic role of these heat shock proteins in melanoma and other cancer cells. , , currently, the molecular basis underlying the more potent antimelanoma activity of aq vs. cq remains undefined. it is noteworthy that aq also displays more potent antimalaria activ- ity, a property attributed before to its increased tropism targeting the acidic food vacuole of the plasmodium parasite, - but addi- tional structural features may contribute to increased potency of the drug. as with its parent compound cq, aq is a lysoso- motropic -aminoquinoline-based tertiary amine, but only aq contains a , -aminophenol-substituent that forms an electro- philic quinoneimine-metabolite upon intracellular oxidation, a reactive intermediate that may be involved in covalent protein adduction. , indeed, other drugs containing aminophenol- pharmacophores cause inhibitory adduction at cysteine-residues of specific target proteins such as ctsb. it is therefore tempt- ing to speculate that in addition to disruption of lysosomal ph control, a physicochemical effect commonly associated with the class of -aminoquinoline antimalarials, covalent adduction of specific protein targets by aq my contribute to its higher © l an de s b io sc ie nc e. d o no t d is tr ib ut e. autophagy volume issue antimelanoma activity, a hypothesis to be tested by future experi- ments. consistent with this hypothesis, using a monoclonal anti- body employed clinically for elisa-detection of aq-adducted plasma protein, we detected the accumulation of aq-modified proteins ( - to -kda molecular mass range) in melanoma cells (fig. a). currently, we are employing proteomic tools in order to elucidate identity and functional implications of specific aq-adducted target proteins in melanoma cells. the concept of repurposing clinical antimalarials (including cq, hydroxychloroquine, primaquine, and artemisinin-deriv- atives) for cancer chemotherapy has recently gained consider- able attention. , , - , , , , aq is in clinical use worldwide (yet not in the united states) as an antimalarial equivalent to cq, and recent studies have shown that aq is superior to cq in the treatment of resistant strains of plasmodium falciparum. remarkably, safety and efficacy of aq-based antimalarial ther- apy are well established, and pharmacogenetic profiling of an aq-metabolizing enzyme (cytochrome p , family , subfam- ily c, polypeptide ; encoded by cyp c ) in malaria patients may improve the safe use of this drug. , taken together, our data suggest that aq is a promising candidate for drug repurpos- ing efforts aimed at undermining autophagic-lysosomal function and proliferative control in malignant melanoma cells. our cur- rent research efforts aim at the identification of specific molecu- lar targets involved in aq-based inactivation of cancer cells, and studies that aim at demonstrating feasibility of aq-based adju- vant chemotherapeutic intervention in preclinical murine models of human melanoma have been initiated. materials and methods chemicals all chemicals were purchased from sigma chemical co. (bafilomycin a , b ; chloroquine, c ; cis-dichloro- diamine-platinum [ii], p ; doxorubicin, d ) except amo- diaquine (fluka, a ). cell culture human malignant a melanoma cells (atcc, crl- ) were cultured in rpmi medium (atcc, - ) containing % bovine calf serum (hyclone, sh . ). lox-imvi human metastatic melanoma cells (a gift from g. paine-murrieta, university of arizona) were cultured exactly as a cells, and g (atcc, crl- ) human metastatic melanoma cells were cultured in mccoy’s a medium (atcc, - ) containing % bovine calf serum. cells were main- tained at °c in % co , % air in a humidified incubator. dulbecco’s phosphate-buffered saline (pbs) and hbss contain- ing . mm d-glucose were from life technologies ( - and - ). transmission electron microscopy cells were fixed in situ with . % glutaraldehyde in . m cacodylate buffer (ph . ), post-fixed in % osmium tetroxide in cacodylate buffer, washed, scraped and pelleted as described recently. , cells were then stained in % aqueous uranyl ace- tate, dehydrated through a graded series ( , , , and %) of ethanol and infiltrated with spurr’s resin (sigma, em ), then allowed to polymerize overnight at °c. sections ( nm) were cut, mounted onto uncoated -mesh copper grids, and stained with % lead citrate. sections were examined in a cm transmission electron microscope (fei) operated at kv with digital image collection. flow cytometric quantification of cellular autofluorescence after aq treatment, cells were harvested, washed and resus- pended in μl pbs, and immediately analyzed by flow cytom- etry (λ ex nm, λ em ± nm) as published recently. rfp-gfp-lc puncta formation assay a cells were grown on -mm glass bottom dishes (mattek, p g- - -c) for live-cell imaging. cells were transfected with an mrfp-egfp-lc construct (addgene, :ptf lc ) fol- lowing a published procedure. twenty-four hours after transfec- tion followed by aq treatment ( μm, up to h), cells were gently washed once with pbs, and phenol red-free dmem sup- plemented with % fbs was added. all images were taken with the zeiss observer z microscope using the slidebook . . . computer program (intelligent imaging innovations, inc.). cell proliferation assay cells were seeded at , cells/dish on -mm dishes. after h, cells were exposed to a test compound (cq vs. aq, . – µm; h continuous exposure). numbers of adherent cells at the time of compound addition and h later were determined using a z analyzer (beckman coulter, inc.). proliferation was compared with cells that received mock treatment. the same methodology was used to establish ic values (drug concen- tration that induces % inhibition of proliferation) indicating antiproliferative potency. flow cytometric analysis of cell viability viability and induction of cell death (early and late apop- tosis/necrosis) were examined by anx a /annexin av-fitc/ propidium iodide (pi) dual staining of cells followed by flow cytometric analysis as published previously. , cells ( , ) were seeded on -mm dishes and received drug treatment h later. cells were harvested at various time points after treatment and cell staining was performed using an apoptosis detection kit according to the manufacturer’s specifications (sigma, apoaf- tst). viable cells are located in the bottom left quadrant (anx a −, pi−), whereas early apoptotic and late apoptotic/ necrotic cells are located in the bottom right (anx a +, pi−) and top right quadrant (anx a +, pi+), respectively. cell cycle analysis cells were seeded at , per -mm dish and left over- night to attach. the next day, cells received treatment with test compounds and vehicle controls. after and h continu- ous drug exposure, cells were processed as published before. cellular dna content was determined by flow cytometry and analyzed using the modfitlt software, version . (verity, vmfltmac ). cellular atp determination cells were seeded at , cells/dish on -mm dishes. after h, cells were treated with test compound (aq ≤ μm). at various time points (≤ h) cells were counted, and atp content per , cells was determined using the celltiter-glo lumines- cent assay (promega, g ) according to the manufacturer’s © l an de s b io sc ie nc e. d o no t d is tr ib ut e. www.landesbioscience.com autophagy instructions as published earlier. , , data are normalized to atp content in untreated cells. mitochondrial transmembrane potential mitochondrial transmembrane potential (Δψm) was assessed using the potentiometric dye , ́ , , ́ -tetrachloro- , ́ , , -́ tetraethylbenzimidazolyl-carbocyanine iodide (jc- ; sigma, t ) following our published procedure. , in brief, cells were trypsinized, washed in pbs, resuspended in µl pbs containing µg/ml jc- for min at °c and % co in the dark, then washed twice in pbs and resuspended in µl pbs. bivariate analysis was performed by flow cytometry with excitation at nm, and mitochondrial function was assessed as jc- green (depolarized mitochondria, detector fl- ) or red (polarized mitochondria, detector fl- ) fluorescence. enzymatic activity of ctsb, l, and d ctsb activity was measured using a fluorimetric ctsb activ- ity assay kit (biovision, k - ), according to the manufac- turer’s instructions as published recently. , cells ( × ) were lysed in . ml of chilled lysis buffer. after min incubation on ice, lysates were centrifuged at , g at °c for min and the supernatant fraction was retained for analysis. μl of cell lysate was incubated with μl of reaction buffer. ctsb substrate (ac-rr-afc; μm final concentration) was then added and the mixture was incubated for h at °c. as a negative control, analysis was performed in the presence of the ctsb/l inhibitor z-phe-phe-fmk (sigma, c ; μm final concentration). the release of free amino- -trifluoromethylcoumarin (afc) was measured using a fluorescence plate reader (λex nm; λem nm; spectramax gemini, molecular devices). protein con- centration of cell lysates was determined using a bca protein assay kit (pierce, ), and cathepsin activity was normalized to protein concentrations. ctsd and ctsl activities were determined using fluorimet- ric assay kits (biovision, k - and k - ) according to the manufacturer’s instructions as published recently. processing of samples and the protocol were identical to the ctsb activ- ity assay as described above with the following modifications: ctsl determination: after lysis, μl lysate were incubated with μl of reaction buffer containing ca (sigma, c ; µm, min) to irreversibly inhibit ctsb, thereby eliminating interference from ctsb-dependent cleavage of the substrate. , ctsl substrate (ac-phe-arg-afc, abcam, ab ; μm final concentration) was then added and the mixture was incu- bated for h at °c followed by afc detection (λex nm, λem nm). as a negative control, analysis was performed in the presence of z-phe-phe-fmk ( μm final concentra- tion). ctsd determination: using ctsd substrate (mca- gkpilffrlk[dnp]-dr-nh , abcam, ab ; µm final concentration) the release of free -methoxycoumarin- -yl acetyl was measured using a fluorescence plate reader (λex nm; λem nm). human stress and toxicity rt profilertm pcr expression array analysis after pharmacological exposure, total cellular rna ( × a cells) was prepared according to a standard procedure using the rneasy kit (qiagen, ). reverse transcription was performed using the rt first strand kit (superarray, ) and µg total rna as described previously. , the human autophagy rt profilertm pcr expression array (qiagen, pahs- za- ) and the human stress and toxicity rt profilertm pcr expression array (qiagen, pahs- a- ), each profil- ing the expression of genes, was run using the following pcr conditions: °c for min, followed by cycles of °c for s alternating with °c for min (applied biosystems, sds). gene-specific product was normalized to gapdh and quantified using the comparative (ΔΔc t ) ct method as described in the abi prism sequence detection system user guide as published earlier. , expression values were averaged across independent array experiments, and standard deviation was cal- culated for graphing. gene expression analysis by real time rt-pcr after aq exposure ( – μm, h), total cellular rna ( × cells) was prepared using the rneasy kit (qiagen, ). reverse transcription was performed using tagman reverse transcription reagents and ng of total rna in a -μl reaction. reverse transcription was primed with ran- dom hexamers and incubated at °c for min followed by °c for min, °c for min, and a chill at °c. each pcr reaction consisted of . μl of cdna added to . μl of taqman universal pcr master mix (roche molecular systems), . μl of gene specific primer/probe mix (assay-by- design; applied biosystems: cdkn a [assay id hs _ m ], ddit [assay id hs _g ], gadd a [assay id hs _m ], hspa a [assay id hs _s ], egr [assay id hs _m ], e f [assay id hs _m ], and gapdh [assay id hs _m ]) and . μl of pcr water. pcr conditions were: °c for min, followed by cycles of °c for s alternating with °c for min (applied biosystems sds). gene-specific product was normalized to gapdh and quantified using the comparative (ΔΔc t ) ct method as described in the abi prism sequence detection system user guide as published earlier. , immunoblot detection cells were lysed in × sds-page sample buffer and heated for min at °c. samples were separated by % sds-page fol- lowed by transfer to protran nitrocellulose membranes (whatman, ba ). membranes were incubated with primary antibodies in % milk-tbst overnight at °c as follows: rabbit anti-phos- pho-rb (ser ) polyclonal (cell signaling technology, ); rabbit anti-phospho-rb (ser / ) polyclonal (cell signaling technology, ); mouse anti-rb monoclonal (cell signaling technology, ); mouse anti-cdkn a monoclonal (cell signaling technology, ); rabbit anti-lamp monoclonal (cell signaling technology, ); rabbit anti-snca poly- clonal (cell signaling technology, ); rabbit anti-rpl a polyclonal (cell signaling technology, ); rabbit anti-myc monoclonal (cell signaling technology, p); mouse anti- tp monoclonal (santa cruz biotechnology, sc- ); mouse anti-e f monoclonal (santa cruz biotechnology, sc- ); mouse anti-becn monoclonal (santa cruz biotechnology, sc- ); anti-ccnd polyclonal (santa cruz biotechnology, sc- ); mouse anti-sqstm /p monoclonal (santa cruz © l an de s b io sc ie nc e. d o no t d is tr ib ut e. autophagy volume issue biotechnology, sc- ); rabbit anti-lc polyclonal (novus biologics, - ); mouse anti-hspa a/hsp monoclo- nal (enzo life sciences, spa- -f); anti-hsp aa /hsp monoclonal (enzo life sciences, spa- -d); mouse anti- amodiaquine monoclonal (thermo scientific, - - ). use of hrp-conjugated goat anti-rabbit (jackson immunological research, - - ) or goat anti-mouse secondary antibody (jackson immunological research, - - ) was followed by visualization using enhanced chemiluminescence detection reagents. equal protein loading was examined using a mouse anti-actb monoclonal antibody (sigma, a ). statistical analysis the results are presented as means (± s.d.) of at least three independent experiments. data were analyzed employing the two-sided student t test; differences were considered signifi- cant at p < . 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( ) - http://dx.doi.org/ . / - ( ) - http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids= &dopt=abstract http://dx.doi.org/ . /journal.pone. http://dx.doi.org/ . /journal.pone. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids= &dopt=abstract http://dx.doi.org/ . /sj.clpt. http://dx.doi.org/ . /sj.clpt. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids= &dopt=abstract http://dx.doi.org/ . /blt. . http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids= &dopt=abstract http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids= &dopt=abstract http://dx.doi.org/ . /s - - - http://dx.doi.org/ . /s - - - http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids= &dopt=abstract http://dx.doi.org/ . /bchm . . . . http://dx.doi.org/ . /bchm . . . . http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids= &dopt=abstract http://dx.doi.org/ . /sj.cgt. http://dx.doi.org/ . /sj.cgt. de:utsches elektronen-synchrotron de sy desy / june dual light-cone model predictions for total and inclusive e+ e annihilation by g~ schierholz ii. institut far theoretisahe physik der universitat hambu.~ and m. g. schmidt :rnstitut filr theoretisahe physik der universitat heidelberg hamburg • notkestieg dual light-cone model predictions for total and inclusive + e e annihilation by g. schierholz ii. institut flir theoretische physik der universitat hamburg, germany and m.g. schmidt institut flir theoretische physik der universitat heidelberg, germany abstract predictions of a recently proposed dual scaling model for the total and inclu-sive e+e- cross section are discussed taking particular interest in preasympto-tic corrections. good agreement with available data is found. recently, we have presented a dual light-cone model for deep inelast ic electroproduction and annihilation! which led to an explicit ansatz for the structure functions f (x) and f (x). in particular, we found a generalized gribov-lipatov reciprocity relation which connects f (x) and f (x) in their physical regions so that the continuation to the deep inelastic anni hilation reg>on becomes exceedingly simple. once our model has been tested in the scat- tering region, we thus can predict the annihilation structure functio n f (x) on firm grounds of the electroproduction data. preliminary spear results show that, at present energies (q ~ gev ), the inclusive cross section does not scale in the annihilation reg ion except 'c near x "' i which is in sharp contrast to the experimental finding of early scaling in deep inelastic electroproduction and raises the question, whether scaling has not yet been reached or even is broken in the timelike re gion. in order to decide this question and before one draws any conclusions again st . k " f . . h bjor en sea >ng or pos>tlve q , one as to examine closely what cur rent seal- ing models predict in the annihilation region and to look for preasy mptotic corrections which we have good reasons to believe play an important role at spear energies. this may reveal that the spear results do not contra dict asymp- totic scaling though (contrary to many augurs), perhaps, they are no t the ex- perimentum crucis for probing parton structures. in this paper we shall discuss the predictions of our model for total and inclusive e+e- annihilation taking particular interest in nonleading (scale breaking) contributions. we shall see that the preliminary spear dat a can be well described in terms of this (scaling) model. the (scattering) structure function f (x) was given by • (x = = n x-a(o)+i f (x) +i c i ( •i i db' : j -i -c +c'+a( )- i i ( (l+x) -~ -x) ' l -q / v) ( i ) where c and cj are determined by netic) target form factor and the the asymptotic behavior of the (electromag- + - ( ) + (i ) transition form factor respecti- "'''""''"'' ., .. , ... , ... "'" '' .. , .. ,.., .•.. '"'"'""'"'"" "'"" '''"''' '''""'~'" '"''""""''"'"''""" ,.,,.,,, . ''"'' '"""'''''"''' ',, ,, ''"'"'"'"''" ''"'""' vely. the normalization of the structure function (i.e.,n) is provided by the adler sum rule (a(o) < i) i f dx f (x) = x ( ) being a consequences of the current algebra constraints with actually led to scaling. the (annihilation) structure function f (x) could most simply be ex- pressed in terms of f (x) by means of the reciprocity relation (which holds for arbitrary c ) =x c '-i i in the following we shall set cj ( ) in accordance with other models ' . we furthermore take c = for mesons (monopole form factor) and c = i for nucle- ons (dipole form factor) respectively. assuming su( ) (exchange degeneracy), nonexoticity in all channels and the photon being a u-spin scalar, we obtain for the nondiffractive part of the pseudoscalar meson octet the (physical) scaling functions t) = - f (x) = - f (x) ( ) and similarly for the annihilation structure functions. !n the case of the baryon (antibaryon) octet we have to allow for a ( ) representation in the baryonic channels. if we assume that the decuplet does not contribute in the scaling region, we would get the analogue of eq. ( ). this might be justified "' for x"' since the ~( ) + n transition form factor shows a slightly faster decrease than the nucleon form factor which suggests a suppression near x = yia the drell-yan relation. but, in general, there is no doubt that the decuplet contributes to the scaling functions. another solution (which treats n and & on the same footing) would be the su( )/quark model results + f p,~ (x) = f ~ > ~ (x) f (x) , ( ) a detailed analysis of the various symmetry aspects allowing for a different threshold behavior of the decuplet contribution which also explains the rather small f n(x)/f p(x) ratio will be given in a forthcoming paper. the pomeron contribution cannot be integrated in the duality scheme so far developed, but has to be added by hand. it is tempting to assume the same ansatz (eq.(l)) for the diffractive term as for the nondiffractive part (here ~( ) = i of course). this can be motivated in our model (having nonlinear tra- jectories) by replacing the s-channel trajectory by some background trajectory without resonances being dual to the porneron ~n accordance with the harari- freund conjecture. here, the threshold behavior (i.e., c ) is, however, no longer determined by the asymptotic behavior of any form factor as in the nondiffrac- tive case. but following the general belief that the background corresponds ) . . d (at least to a four and f ve quark ass gnment we conclude c = an c = for mesons and baryons respectively. hence, the pomeron contribution is strongly suppressed near threshold compared to the nondiffractive part which seems to . . d d . . ii be supported by compar son of neutr no an e ectropro uctljn exper ments. in the following we take the su( ) solution for the nucleon octet. we further- more assume that the pomeron be a su( ) singlet. then, the normalization of the pomeron contribution is the only free parameter. the intercept of the regge trajectory is taken to be a(o) = . would rise linearly up to the a , f we have drawn f p(x) taking n pomeron (what would come out if the trajectory resonance with a'(o) = i gev- ). in fig. i = . which gives a good fit to the data. also indicated is the pomeron contribution. this is significant only at small x as is to be expected. in the case of the meson octet there is no ambiguity as far as the su( ) structure is concerned. here the pomeron coupling is via factorization deter- mined by the ratio anp /opp = / (note that the x ~ limit of the scaling tot tot functions does not depend on c ). the resulting scaling function is shown in fig. . due to the different threshold factor, f t i(x) increases much faster near threshold than the proton scaling function. the pomeron contribution again is negligible for x ~ but is considerably larger for medium x (x ~ . ) than in the case of the proton. the annihilation structure functions can be deduced from for large x we have f (x ) "' fig. employing xa( )+ for the the reciprocity relation ( ). nondiffractive term and f (x) ~ x for the pomeron contribution. so far we have concentrated on the p on and nucleon (octet) structure func- tions only. but any other particle h which gives rise to scaling in the deep inelastic scattering region, will contribute a portion to the large-q total + - inclusive e e cross section as well. if we had exact su( ), e.g., we would get / times as many signals as if there were only pions. in the case that the particle h is unstable (broken su( )) this gives of course, a contribu- tion to the inclusive spectrum of its decay products as shown in fig. a. in the imaginary part of the (annihilation) compton amplitude this process (fig. a) corresponds to the double h exchange diagram as drawn in fig. b for p decaying into two pions. as is well known, this diagram (q > ) gives rise to anomalous singularities which certainly are not included in the pion structure function f ti(x) so far considered. the reason being that our model only accounts for normal threshold singularities. hence, it is plausible to add these anomalous singularity contributions to the pion (annihilation) structure - ti function f (x), whereas the normal threshold part can be thought of being al- ready included in our model. in the scaling limit (q + oo) the p production diagram gives, in the zero width approximation, rise to the (anomalous) cut contribution (supplementary to the normal threshold pion scaling function f ti(x)): x m i (m p dn n :f o (.!) + m _n_ ) ( ) p n p 'it i-n pcm and similarly for any other resonance (if. say the p would decay into a pion and a different particle of mass m, formula ( ) had to be devided by and the function be replaced by (m~-m~n+; n/i-n)). in this approximation the p is forced to be on the mass shell so that the (spin averaged) p structure function appears under the integral. for fi(x) (as well as for the other su( ) partners) we make the same ansatz as for the pion structure function (apart from a possibly different c ) which leads to the analogue of eq.( ). it is tempting to assume c = also (for the nondiffractive part) as one would expect from su( ). other resonances like, e.g., the a which prominently decay into three and more particles can be handled in a similar way. in case of the a , e.g., we would have another pion rung in fig. b due to the cascade a + pti + ti. for finite q preasymptotic corrections resulting from kinematical factors become very important in expression ( ), especially for large x, even at the highest spear energy (q = gev ). this happens because the dominant contri- - p but ion f/ (x) to the integral ( ) a( )+ ~ x ), whereas comes from large arguments of f (x) (remember the somewhat higher resonance mass gives rise to threshold factors which sensitively cut off this region. thus, in order to make substantial predictions at spear energies, we definitely have to include these effects. in the following we shall quote the results only, but will g~ve a de- tailed analysis of these corrections in a more extensive paper. we shall now assume the validity of the callan-gress relation in order to define the scaling function f (x) (in ref. i we have argued that the callan- gress relation should hold irrespective of the spin of the constituents). in the scaling limit (q ~ oo) the callan-gress relation also is maintained for the . . ( . . . . f cut contr~but~ons ) wh~ch then leads to the ~nclus~ve cross sect~on or + - e e ~ h + x: doh q dx = (i - - h ) f (x) where x if ( ) = gev ), how-= p/v q~ and sh = - ~ x /q . for finite q (even q ever, the callan-gress relation no longer holds for the resonance terms but threshold factors become involved which have a considerable effect on eq.( ). in fig. we have drawn our prediction for the (total) charged inclusive + - e e ~ ti + x cross section taking into account (besides the pion contribution) the lowest lying resonances , commonly assuming c = which p, a and b and their octet may be justified upon symmetry partners and arguments. in the small x region (large x) the resonance terms provide by far the dominant contribution, whereas they are negligible for~~ . . hence, we are not sur- f - < prised that scaling breaks down at spear energies or x ~ . . in fact, the shape and order of magnitude of the predicted inclusive agreement with the preliminary spear data. • a precise cross section is in . predict~on depends, however, on the effect of the higher (excited) resonances like a , f, etc. although we believe that their contribution is small at spear energies due to the increasing mass and a likely more suppressing dtell-yan threshold factor. we also have looked at the angular stantial deviation from the asymptotic distribution is absolutely flat in the distribution of the form ~ !+cos . at pion q and find a sub- gev the pion - < region x ~ . (which accounts for most of the events) and beyond that region gradually turns over into the asymptotic form. for increasing (decreasing) q the boundary between these two regions is shifted towards lower (higher) ~ being consistent with the asymptotic distri- bution. the total cross section is given by the energy conservation sum rule r + - cr(e e + hadrons) " . i dx ( ) =-i h x where the sum s over all participating hadrons. we now assume that all the available energy is carried away by pions and kaons and ealculate the total cross section from the inclusive spectrum of these particles (note that in our model the neutrals are produced with the same strength as charged particles). the kaons are found to contribute roughly % to the total cross section. the results is shown in fig. and compared with the world's data. at higher q the predicted cross section is substantially smaller than the experimental cross section which is somewhat surprising. we would have expected that both roughly agree since the predicted inclusive cross section is consistent with the pre- liminary spear data. • in order. to explain this (energy crisis ) a large fraction of the energy has to be carried away by neutrals or by particles other than pions and kaons (perhaps baryons). the general feature that the ratio r increases with energy, however, is well reproduced. so far we have assumed perfect scaling for the structure functions. neglect- ing curvature of the regge trajectories, we obtain that the preasymptotic cor- rections to our scaling functions can, in first order, be accomodated by rescaling of the variable x: x+ x = x a l+ _ bx q a= (a(o)+ ) i a'(o), ( ) b = < + c - a(o)) i a'(o) where a is meant to be the trajectory in the photon channel (note that a and b do not depend on the external masses). the variable x' by bloom and gilman (here a = ) and by rittenberg and has long been r b • . u nste n advocated and for electroproduction allows the concept of scaling to be extended down to very low , .. ,, '"" ,,.,, ,,,,.,,,, ''"""''"'"''' ....... , ,,,, '''""' ·~··~·"'' '' values of q . for proton targets we would predict (a(o) = . ) a= . gev and . .. b = . gev being in not too bad agreement with exper ment. in the annlhlla- tion region the substitution ( ) leads to higher effective x values and, hence, to higher cross sections because of the singular behavior of the scaling func- tions at x + oo. the resonance contributions which account for most of the cross section will, however, not very much be effected by these corrections since they are confined to smaller x in the resonance structure functions. in our model (s,u) terms do not contribute to the current algebra fixed pole and, hence, do not survive in the scaling limit. however, they may give r~se to nonnegligible contributions at finite q , especially in the very large x region as has been emphasized by satz. from su( ) and nonexoticity we derive the general relation -n vw (s,u) = - (i ) we see that neutral particles contribute with a sign opposite to charged par- ticles. this sets, of course, an upper limit to the (s,u) terms because the total structure function has to be positive definite. hence, we cannot expect that the (s,u) terms contribute much to the total cross section since most of the contributions cancel out. but they might have a substantial effect on the neutral to charged ratio and lead a way out of the energy crisis. the most challenging question now s that of the asymptotic value of r. in order to draw any conclusions from our model we have to include the higher mesons and the baryons which might give a sensible contribution at very high energies. for a finite number of resonances (being in the spirit of our model with nonlinear trajectories) r will tend to a constant what we would expect if qed continues to hold at very small distances. references !. g. schierholz and m.g. schmidt, phys.lett. b, ( ); slac report no. slac-pub ( ), to be published in phys. rev. . v.n. gribov and l.n. lipatov, phys.lett. b, ( ); yad.fiz. • ( ) [sov.j.nucl.phys. • ( )) ; for scaling models and further literature see: g. schierholz, phys.lett. b, ( ). . b. richter, talk presented at the conference on lepton induced reac- tions, university of california, irvine ( ); g. goldhaber, talk presented at the frlihjahrstagung der deutschen physikalischen gesell- schaft, desy, hamburg ( ). . we shall not take into account corrections on the daughter level which were necessary to obtain a selfconsistent fixed pole residue (for details see ref. ). we have convinced ourselves in the case of nucleon compton scattering that these corrections are indeed negligible. on the other hand, the model should not be taken too seriously on this level. . g. benfatto, g. preparata and g.c. rossi, rome report no. infn ( ). . j. gayler, proceedings of the daresbury study weekend, - june, . . e.d. bloom and f.j. gilman, phys.rev.lett. , ( ). . m. chaichian, h. satz and s. kitakado, nuevo cim. a, ( ). . g. schierholz and m.g. schmidt, to be published. . s.j, brodsky and g.r. farrar, phys.rev.lett. ]l, ( ); c. alabiso and g. schierholz, slac report no. slac-pub ( ), to be published in phys.rev. . d.h. perkins, oxford report no. - ( ). . for a(o) = . we would have to allow a higher normalization of the scaling function to obtain a fit of comparable quality. . for a thorough discussion of this diagram in respect to the scaling functions see: r. gatto, p. menotti and i. vendramin, ann. phys. • i ( ). . - h the scaling function f (x) s always understood spin averaged. if the sp n of particle h is not detected, eq.( ) has to be multiplied by j + i. . particle data group, rev.mod.phys. ~. part ii, i ( ). . had we included kaons also, we would have obtained an energy splitting up to larger values of x. . note that the kaons account for % of the data, whereas the nucleon contribution is found to be very small. . there is also the possibility that the normalization of the scaling functions deviates from that prescribed by the adler sum rule due to su( ) and exchange degeneracy breaking effects. . c.h. llewellyn smith. cern report no. th. ( ). . v. rittenberg and h.r. rubinstein, phys.lett. b, ( ]). . f. brasse et al., nucl.phys. b, ( ). . h. satz, nuovo cim. a, ( ). our (s,u) terms are, however, bounded for large x. but they depend very much on the imaginary part of the trajectories. figure captions fig. i fig. fig. fig. the nucleon and pion scaling functions. the shaded area corre- sponds·to the slag electroproduction data. the resonance production diagrams. prediction of the charged pion inclusive cross section. predicted total cross section compared to the world's data. x z z ::: w ::: ~ w i.c'! ~ .... - .... ;:) ..c ..c - -::: i i \ i \ r-i ol \ n i,c \ \ \ \ \ \ - \ z \ \ \ z \ \ \ :::: q_ \ q_ \ u") u") n - -.:r -x c) ......... (',i u. i . i -. - -·ru - n - . ' i.i: •' '. . . r-o "vcj = gev n > ' ~ <:) . . . :: . ~ - c o . ·'fcj = gev a. "' ~ cl .... ro - . - bll>< 'fc = gev uu n ct . . . . . . x : p fc fig. i +'i . b'i -. vi ; c e u . ro .t::. t ". i +t:.) . t:.) - b . ii n:: . o cea o frasca tl y y. a frascati j.l rt n slac (preliminary) u physics today mar.' t. . . i fig.t. . ". . vcj [gev] applications and perspectives of multi-parameter flow cytometry to microbial biofuels production processes applications and perspectives of multi-parameter flow cytometry to microbial biofuels production processes teresa lopes da silva, josé carlos roseiro and alberto reis laborató rio nacional de energia e geologia, i.p., unidade de bioenergia, estrada do paço do lumiar , - lisboa, portugal review conventional microbiology methods used to monitor microbial biofuels production are based on off-line analy- ses. the analyses are, unfortunately, insufficient for bioprocess optimization. real time process control strat- egies, such as flow cytometry (fc), can be used to monitor bioprocess development (at-line) by providing single cell information that improves process model formulation and validation. this paper reviews the current uses and potential applications of fc in biodiesel, bioethanol, biomethane, biohydrogen and fuel cell processes. by highlighting the inherent accuracy and robustness of the technique for a range of biofuel processing param- eters, more robust monitoring and control may be imple- mented to enhance process efficiency. biofuel processing in the midst of the energy crisis, second-generation bio- fuels (derived from lignocellulosic agriculture and forest residues and from non-food crop feedstocks) and third generation biofuels (derived from microbes and microal- gae) are considered to be viable fuel alternatives. in order for these fuels to be sustainable, appropriate conversion and process management technologies need to be opti- mized [ – ]. until recently, biofuel process monitoring has been done by conventional analyses such as dry cell weight or serial dilution methods. these data are usually only available a considerable time after the sample is taken. other methods such as optical density or capaci- tance monitoring, though faster, only provide average data for the microbial population [ – ]. an alternative analytical technique, fc, is used to both qualitatively and quantitatively assess biological and physical characteristics of individual cells almost in real time. fc can be used in bioprocess monitoring to obtain information from heterogeneous and complex microbial samples faster and more accurately than with convention- al microbiological methods. complex bioprocesses require almost real time insight to develop dynamic process control strategies for improved performance, quality, productivity and process yield [ ]. this review explores the current shortcomings in biofuel processing and introduces fc as corresponding author: silva, t.l.d. (teresa.lopesilva@lneg.pt). keywords: biodiesel; bioethanol; biomethane; biohydrogen; microbial fuel cells; bioprocess monitoring. - /$ – see front matter � elsevier ltd. all rights reserved. doi: . /j.tibtech. a potential tool to optimize production and conversion processing. current biofuel processing shortcomings biodiesel processing oils and fats are the main raw material for biodiesel (box ) production. thus, identification of high lipid-pro- ducing microbial strains is a prerequisite for sustainable and economically-viable fuel production from microorgan- isms [ , ]. growth conditions strongly influence cellular lipid content in microorganisms [ ] so that cellular lipid content should be monitored throughout bioprocess devel- opment to optimize control strategies and enhance yields. at present, most of the available literature discussing biodiesel production from microorganisms has used con- ventional microbiology techniques to monitor microbial lipid content [ – ]. these are time-consuming methods that generate high amounts of waste (organic solvent) that are harmful to the environment if not recycled by distilla- tion. in addition, these methods require large amounts of biomass for sufficient subsequent lipid extraction [ ]. for example, at least mg of lipid per sample should be extracted and gravimetrically evaluated. thus, assuming an average % (w/w) lipid content, at least – mg dry weight biomass is required. oleaginous microorganisms, which normally contain more than % oil (w/w), are of interest in biotechnology as an alternative source of biodiesel [ ]. unfortunately, independent of the organism used, lipid content data is usually only available a considerable time after the sample is taken during the microbial lipid production, too late to alter process controls. therefore, quick and accurate esti- mates of oil content are needed to optimize oil production or to expand biofuel production bioprocesses. bioethanol processing bioethanol (box ) production is similar to brewing and wine production. in yeast (saccharomyces cerevisiae) fer- mentation, yeast cells are subjected to adverse conditions: limited nutrients, high temperature, ethanol toxicity and osmotic stress from substrate sugars [ ]. these nutrient deficiencies are intensified by the microenvironments formed in large scale fermentors as a result of inefficient mixing. as cells circulate within the bulk of a large-scale . . trends in biotechnology, april , vol. , no. mailto:teresa.lopesilva@lneg.pt http://dx.doi.org/ . /j.tibtech. . . 	lopes da silva et al 	applications and perspectives of �multi-parameter flow cytometry �to microbial biofuels production processes 	biofuel processing 	current biofuel processing shortcomings 	biodiesel processing 	bioethanol processing 	gaseous biofuels 	microbial fuel cells (mfcs) 	fc: an overview 	fc for bioprocess optimization 	lipid content 	cell size 	membrane potential and membrane integrity 	enzyme activity 	different microbial consortia 	reactive oxygen species (ros) 	inhibitory compounds 	concluding remarks 	references volume , number causes and valuation of fatalities saved under the energy crises: a case study of california betty yei-chou chu and geoffrey e. nunn* during the first six months of , california experienced a significant reduc tion in traffic fatalities compared to the same period of . there are numerous reasons that account for the reduction. some can be identified and some cannot. a major factor of course is the serious fuel shortage that occurred during the period. six months data now have become available, and it is possible to analyse the reasons underlying the reduction. this paper focuses on two questions. first, what impact did each of the various factors have; and second, what is the eco nomic value associated with the reduction in fatalities. in order to calculate the reduction in fatalities it is necessary to estimate the number of fatalities that would have occurred under normal non-energy crises conditions. this is the objective in section i. section ii analyses specific factors contributing to the reduction in fatalities and attempts to estimate the fatalities saved that can be attributed to each factor. section iii estimates the douar value of the total reduction and the value of each of the contributing factors. finally, in section iv the major findings are summarized. i. the reduction in fatalities historically, according to studies done by the california highway patrol, the number of fatalities has been determined by two major factors.^ the first is the risk in driving as measured by fatalities per million vehicle miles. the trend in the fatality rate has been decreasing at a decreasing rate. the second is the degree of exposure to risk and is determined by the amount of driving done by california drivers. in order to find the fatality rate per million vehicle miles, it is con venient to use motor vehicle gallonage, which is one of the basic indicators of the total volume of driving. motor vehicle gallonage is defined by the california highway patrol as follows v mvg = total taxable gallonage -f total diesel gallonage — total aviation gallonage — total refund gallonage the figures for mvg are presented in column ( ) of table . total actual state wide mileage can be obtained by multiplying mvg by the miles-per-gallon indices compiled by the california highway patrol and which appear in column ( ). *san jose state university, san jose, california. the review of regional studies the fatality rate per million vehicle miles is the ratio of the total number of fatalities, column ( ), to statewide mileage. this ratio is shown in column ( ). a graphical expression of the result is presented in figure . the trend in the fatality rate can be estimated by fitting a regression line of the form y = a - b/x, where y is the fatality rate per million vehicle miles, a and b are constants, and x is the year. the number is assigned to , to , ..., to . the application of ordinary least squares yields the trend line y = . + x therefore, the expected fatality rate for is: y = . = . . the expected number of fatalities for the first half of can be found by multiplying the expected statewide vehicle miles by the expected fatality rate. the former has not been calculated here. however, based on normal growth trends, statewide vehicle miles were expected to grow . % for the first half of according to the california highway patrol.® it follows that expected statewide vehicle miles is . billion miles x ( -|- . ) = . billion miles. thus, the expected number of fatalities for the first half of under normal conditions is victims. the actual n imber is , which is % below the expectation. ii. factors accounting for the reduction in fatalities according to the california highway patrol and other safety agencies,^ the factors accounting for the reduction which can be identified are: ( ) reduced travel, ( ) the lowering of the speed limit to miles per hour, ( ) a reduction is speed dispersion, and ( ) the conversion to daylight saving time. other factors are not easy to identify but may include such things as increased seat belt usage, greater emphasis on drunk driver enforcement and increased driver awareness of fuel conservation techniques. . reduced travel the reduction in fatalities attributable to reduced travel can be gauged by calculating the percentage drop in vehicle miles. total statewide vehicle miles of travel for the first half of was . billion miles. the corresponding table january through june fatalities per milhon vehicle miles number of persons motor vehicle killed gallonage" mpg index statewide vehicle fatality rate** mileage* . . . . . . . . . * unit: billions **per million vehicle miles source: calculated from the data provided by the department of california highway patrol, letter dated december , , file number .a .a . volume , number figure is . billion miles, which is % below . in addition, based on normal growth patterns, vehicle miles were expected to grow at . % for the first half of .'' it follows that the volume of travel was . % below normal. since miles driven is an indication of accident probability, traffic fatalities should have fallen . % below expectation. the projected fatality rate for jan uary through june is . per million miles. multiplying this fatality rate by the expected . billion miles gives expected victims. since travel is estimated to have been down by . %, the expected rate times actual vehicle miles yields victims ( . billion miles x . ). reduced travel accounts for the difference . . permanent daylight saving time when permanent dayhght saving time was introduced on january , , it was believed that traffic accident levels might be favorably affected. perma nent daylight saving time only affects january, february, march and april; may and june are not affected. accident rates are a function of visibility. the better the lighting conditions in late afternoon hours, when accidents occur most fre quently, the more likely the chance of fewer accidents. the detrimental effects of reduced visibility in the morning hours were expected to be more than offset by the beneficial effects of increased visibility in the late afternoon and early evening hours. a crude estimate of the effect of daylight saving time can be derived from the data in table . the calculation has to be based on january, february, and march, the only months for which data are available at this writing. historically, . percent of the fatalities in the first quarter have occurred during the extreme hours, - a.m. and - p.m. if we assume that the percent of fatalities in occuring during these hours would also have been . % had daylight saving time not been imposed, a calculation for the number of fatalities saved can be made from the following equation: ( + x) = ( + x) . . solving for x gives , which is the number of fatalities saved. presumably, this figure would be larger if april is included. however, the figure as it stands is probably an overestimate. the shift in the hourly frequency distribution of fa talities occuring during early cannot be attributed entirely to daylight saving time. night-time closing of gasoline stations doubtlessly increased the percent age of driving done during the day. in addition, it can be assumed that some drivers purposely avoided driving during the extreme periods because of longer waiting lines at gasohne stations. nevertheless, the statistics in table dramati cally bear out the effect that daylight saving was predicted to have — a sharply higher fatality rate during morning rush hour and a sharply lower rate in the afternoon hour — and thus it should be fairly reasonable to assume that our estimate of fatahties saved is in the right ballpark. table percent of total fatalities in california occurring between - a.m. and - p.m. (jan.-march ) - avg - a.m. - p.m. totals the number of fatalities in california that occurred between - a.m. and - p.m. (jan.-march ) is . the total number of fatalities that occurred in this period is . source; "a study on accident changes under energy crisis," california highway patrol, california highway patrol, sacramento, july . volume , number . reduction in driving speed there was a large reduction in high speed driving during the energy crisis. one factor was increased driver attention to gasoline efficiency. in ad dition, on january , the mph speed limit was imposed. the speed hmit on most california highways previously had heen mph. the adverse effect of speed is undeniable. higher speeds reduce vehicle stopping and maneuvering abihty, and magnify existing tire and headlight limi tations, road design inadequacies, driver skill deficiences, and the effects of alcohol. data from the bureau of public roads," the cornell aeronautical lab,' the state of virginia," and the state of california" support increasing fatality probability with increased speed at crash impact, and especially at the upper speed ranges. another factor associated with speed is speed dispersion." drivers travelling either well above or well below the average speed of traffic will be involved in a disproportionate number of accidents. thus, it is also dangerous to drive too slow in relation to the flow of traffic. since curtailment of high speed driving during the first half of implies a smaller speed dispersion, this factor would additionally account for fewer fatalities. to date, there have heen no studies that have successfully estimated the relationship between speed and the totality of accidents. attempts in this regard, according to the chp, have been consistently discouraging.^^ thus, any direct estimate of the number of fatalities deterred attributable to speed reduction seems to be ruled out. a rough approximation, however, can he obtained indirectly. we have cal culated that the number of fatalities saved is , and that reduced travel ac counts for and daylight saving time accounts for . the remaining would be attributable to reduced driving speed and to other factors both known and unknown. among the "known" factors are those identified in table . the percentages reported in the table indicate the reduction in fatalities attributable to each factor, as assessed by the national safety council. since the net impact is % of the reduction in total fatalities, this would account for fatahties saved. thus, assuming that other factors are small enough to ignore, fatalities can he attributed to reduced driving speed. table factors contributing to the reduction of motor vehicle traffic fatahties, jan uary— april vs january — april . reduction in average occupancy change in day-night travel change in type of road used increased use of safety belts motorcycles, pedalcycles, small cars, age of driver source: statistics division of national safety council, october . — % - % - % - % + % total — % the review of regional studies iii. the average value of each life saved it is hard to place a dollar value on a life. if asked to value one's own life, one would say it is priceless. however, as an income producer an individual is human capital, the value of which can be determined by looking at his age and his earnings stream. we shall employ this reasoning to place an estimate on the value of the fatalities saved. one problem associated with the estimation is that would-be victims are un known. we, therefore, have no way to know would-be victims' ages and potential incomes. to cope with this we shall use averages, the average age of the popula tion of california in , and the per capita income in california in the first six months of . total income in california in the first half was $ , million^- and the population in the same period was , , ." thus, the estimated average in come per capita is $ . . the present value of an income stream is pv = ( +i) ( +i)' rn ( -fi)" where pv stands for present value; r ̂ ,r , ... r n represent income in the st, nd, ... nth year; i is the interest rate; and n is the total number of years one will earn income. the interest rate we are adopting is the yield to maturity on long-term u.s. government bonds, which in was about . % between jan uary and june." the average age of the population of california, calculated from census data, is . for and . for .^'' thus, it is reasonable to believe that in the average age in california is still close to . according to studies undertaken by the social security administration, half of female workers and one-third of male workers claim benefits at the age of .^" twenty percent of the women and thirty-seven percent of the men claim postponed benefits. the rest, % of the women and % of the men, retire at the age of . if we consider as the "normal" age for retirement, early re tirement and postponed retirement to some extent offset each other. therefore, we reach the following adjusted percents in retirement ages: percent retiring at after since % of the california population are women and % are men," the adjusted percent of retirement age for the overall population of california be comes . %, . %, and . % that retire respectively at , at , and after . by using the same method to adjust early retirement and late retirement, the percent working until age becomes . % and the percent working until volume , number becomes . %. thus the estimated n, the total number of years income would he earned is: . ( - + . ) + . ( - + . ) = . = n. according to actuarial estimates, the life expectancy for a male of years is . and for a female is . years.^*' thus the average person living in california in could expect to live beyond the age of , and it should not affect our results too adversely to assume that all would-he fatalities will live to retirement age. if incomes remain constant from now on, the average value of a life saved is: pv = $ . ( h h • • • • '( + . ) ( + . ) ^ = $ , . in dollars. ( + . )^ however, it is unrealistic to assume that per capita income will remain constant. therefore, we will calculate two alternative figures that assume that average income grows over time. table shows figures for per capita income in the past years in california. per capita income has grown at an average rate of %. if we assume that for the next years, per capita income grows at the same rate, the present value of a life saved becomes: pv = . ( + . ( + . ) = $ , . in dollars. ....+ ( + - )^ ( + . )^ alternatively, if we consider that the bond rate is the return to non-human capital, that average income is the return to human capital, and that in equili brium they would grow at the same rate, then we have the following estimate: - ) pv ̂ . ( —^ ! ^ . ( . ) = $ , . in dollars. ....+ ( . ) ( . ) a case can he made that this calculation is the most realistic one. bond yields today are high hy historical standards, probably because of inflation expectations. if these expectations are borne out, that is, if the rate of inflation is higher in the future than it has been historically, then per capita income in california should grow at a higher rate than the historical figure of %. estimates for the total value of lives saved are presented in table . the table gives estimates of the aggregate value, and the value that can he assigned to each of the factors responsible for the fatality reduction. table personal income, population, per capita income and percent change of per capita income in california, - personal income (million $) population (thousand) per capita income ($) . . . . - . . . . . . . . . . . . . . . . . . . . . percent change of per capita income . . . . — . . . . — . . . . . — . . . . — . . . . . . . . table (continued) personal income (miuion $) population per capita income percent change of (thousand) ($) per capita income . . . . . . . . . . . . . . . . . source; compiled from the california statistical abstract, , , , , and , sacramento, california. table factors responsible for reduction in fatalities and dollar value of lives saved under energy crisis in cali fornia, january through june ( dollars) value of lives saved no. of lives percent of i ^ ; factors responsible saved total decrease constant income increases income mcrease income at % a year at % a year no. of lives percent of saved total decrease constant income reduced travel permanent daylight saving time slower driving speed , , . , , . , , . , , . , , . , , . , , . , , . , , . , , . , , . , , . , , . , , . , , . volume , number iv. conclusions the reduction of fatalities in california in the first half of was due mainly to the energy crisis. the factors largely responsible were reduced travel, permanent daylight saving time, and slower driving speed. reduced travel ac counted for . %, permanent daylight saving time accounted for . %, and slower driving speed accounted for . % of the reduction in traffic fatalities. the number of fatalities saved is estimated to be . by using various as sumptions, a dollar value can be assigned. if nominal income remains constant from now on, the estimated value is $ , , . . based on historical long-run data, income has grown at % per year in california. assuming that this trend con tinues, the estimated value is $ , , . . alternatively, if per capita income grows at the same rate as the yield to maturity on long-term bonds, the esti mate becomes $ , , . . these figures, of course focus on only one aspect of value saved which is human capital. no attempt is made to estimate other costs that were deterred such as legal expenses, police costs, and medical and funeral expenses. footnotes . see "a study on accident changes under energy crises," california highway patrol, sacramento, cali fornia, july , p. . . letter from robert a. bieber, commander of analysis section, california highway patrol, december , . file no. .a .a . . "a study on accident changes under energy crises," op. cif., p. . . such as, ibid.; "statement regarding january — june accident experience in california," california highway patrol, july , ; "council tells factors behind traffic death drop," national safety council, sept. , ; "factors contributing to the reduction of moton^vehicle traffic fatalities, jan uary— april vs. january — april ," national safety council; letter from cordell smith, co ordinator of highway safety, to governor john d. vanderhoof, state of colorado, june , . . "a study on accident changes under energy crises," op. cif., p. . . david solomon, "accidents on main rural highways related to speed, driver, and vehicle," bureau of roads, u.s. department of commerce, gpo, washington, d.c., july . . "preliminary tabulation on traveling speed and injury producing rural automo^e accidents acir data," cornell aeronautical laboratory inc., july . . "virginia traffic crash facts, ," department of state police, richmond, virginia. . "report of fatal and injury motor vehicle traffic accidents, ," state of california, sacramento, california. . "a study on accident changes under energy crisis," op. cit., pp. - . . ibid., p. . . compiled from business week, april , ; may , ; june , ; july , ; august , ; and september , . . california statistical abstract, , table b- , p. . . sampling by random (sample size — ) from the wall street journal, january — june . . calculated from general population characteristics of california, u.s. department of commerce, bureau of the census, october , pp. - . . social security bulletin, march , p. . . general population characteristics of california, op. cit. . obtained from farmers' insurance group and atena insurance company. references bieber, robert a., commander of analysis section, california highway patrol, letter, december , , file no. .a .a . business week, new york, mcgraw-hill, april , ; may , ; june , ; july , ; august , ; and sept. , . the review of regional studies california highway patrol, "a study on accident changes under energy crisis," sacramento, california, july . california highway patrol, "statement regarding january — june accident experience in califoriiia," july , . california statistical abstract, sacramento, california, - . cornell aeronautical laboratory, inc., "preliminary tabulation on travelling speed and injury producing rural automobile accidents acir data," july . general population characteristics of california, bureau of the census, u.s. department of commerce, october . national safety council, "council tells factors behind traffic death drop," chicago, illinois, sept. , . national safety council, "factors contributing to the reduction of motor vehicle traffic fatalities, jan uary— april vs. january — april ," chicago, ., oct. . smith, cordell, coordinator of highway safety, letter to governor john d. vanderhoof, state of colorado, june , . social security bulletin, vol. , no. , u.s. department of health, education and welfare, march . solomon, david, "accidents on main rural highways related to speed, driver, and vehicle," bureau of public roads, u.s. department of commerce, gpo, washington, d.c. july . state of california, "report of fatal and injury motor vehicle traffic accidents, ," sacramento, cali fornia. virginia department of state police, "virginia traffic crash facts, ," richmond, virginia. wall street journal, january — june . immobilizing [fefe]-hydrogenase mimics to metal–organic frameworks for enhanced hydrogen production science bulletin ( ) – contents lists available at sciencedirect science bulletin journal homepage: www.elsevier.com/locate/scib research highlight immobilizing [fefe]-hydrogenase mimics to metal–organic frameworks for enhanced hydrogen production https://doi.org/ . /j.scib. . . - /� science china press. published by elsevier b.v. and science china press. all rights reserved. e-mail address: dfsun@upc.edu.cn daofeng sun school of materials science and engineering, college of science, china university of petroleum (east china), qingdao , china production of hydrogen from water by solar-energy conversion has long been considered a promising way to solve the climate change and energy crisis [ ]. however, some critical issues at this stage, such as catalysts for hydrogen evolution with high efficiency and low cost, definitely hinder the practical application of photo- catalytic hydrogen production from water. [fefe]-hydrogenase, an excellent natural biological enzyme catalyst bearing unique organometallic clusters with noble-metal-free element, is most efficient in reducing protons to hydrogen and demonstrates remarkable turnover frequencies (tof – s� per active site) [ ]. with the crystal structural elucidation of [fefe]-hydroge- nase, numerous [fefe]-hydrogenase mimics have been synthesized to develop photocatalytic systems for hydrogen generation [ – ]. to date however, there are still no artificial [fefe]-hydrogenase mimics that can reproduce the high reactivity of natural [fefe]- hydrogenase, largely because of the low stability of [fefe]-hydro- genase in photocatalytic process. therefore, considering the fact that a natural [fefe]-hydrogenase is deeply embedded within the protein matrix, it is important to explore the external matrix of the [fefe]-hydrogenase mimics. emerging as an intriguing class of porous crystalline materials, metal–organic frameworks (mofs) can be easily functionalized at the molecular level [ ]. pioneering works on the incorporation of [fefe]-hydrogenase mimics into mofs to create heterogeneous catalysts has been demonstrated improved photocatalytic activity and stability for hydrogen production [ – ]. among these previously reported studies, [fefe]-hydrogenase mimics were incorporated into a photosensitizing zirconium-porphyrin mof by direct coordination or into a non-photosensitizing mof by post-synthetic exchange/covalent bond with [ru(bpy) ] + as a pho- tosensitizer. although some achievements have been made in combination of [fefe] catalyst and mofs, immobilizing [fefe] catalyst to photosensitizing mof by covalent bonds is still a challenging task. recently, yuan’s group [ ] reported the incorporation of an [fefe]-hydrogenase mimics into an [ru(bpy) ] +-derived photo- sensitizing uio-type mof by a facile click reaction to generate a new hydrogen evolution catalyst uio-mof-fe s (fig. ) [ ]. in this work, the construction of photosensitizer and [fefe] catalytic active site in the same framework could enhance the electron transfer process in a local microenvironment by comparison to [ru(bpy) ] + as a photosensitizer. besides, the incorporation of [fefe] catalytic active site via click reaction is more efficient com- pared with ligand exchange or weakly coordination strategy. after h of photocatalytic reaction, the uio-mof-fe s produced a total of lmol h with ascorbic acid as a proton source and a sac- rificial electron donor. the good performance of uio-mof-fe s can be ascribed to greatly improved stability by the protection from the framework, as well as the efficient electron transfer between the photosensitizer and the [fefe] catalytic site. in summary, this work may provide a new solution for incorpo- ration of the [fefe] catalytic center into a photosensitizing mof by judicious design of the ligands. meanwhile, the good performance of this artificial [fefe]-hydrogenase mimics system demonstrates that this approach is a promising strategy to stabilize the [fefe] catalyst and improve the photocatalytic efficiency of hydrogen evolution in water. conflict of interest the author declares that he has no conflict of interest. https://doi.org/ . /j.scib. . . mailto:dfsun@upc.edu.cn https://doi.org/ . /j.scib. . . http://www.sciencedirect.com/science/journal/ http://www.elsevier.com/locate/scib fig. . modification of uio-mof via a click reaction for incorporating [fefe] catalytic sites to form new catalysts uio-mof-fe s . reprouduced with permission from ref. [ ]. copyright elsevier. d. sun / science bulletin ( ) – references [ ] gray hb. powering the planet with solar fuel. nat chem ; : . [ ] frey m. hydrogenases: hydrogen-activating enzymes. chembiochem ; : – . [ ] adams mw, stiefel ei. biological hydrogen production: not so elementary. science ; : – . [ ] cammack r. hydrogenase sophistication. nature ; : – . [ ] tard c, pickett cj. structural and functional analogues of the active sites of the [fe]-, [nife]-, and [fefe]-hydrogenases. chem rev ; : – . [ ] cohen sm. postsynthetic methods for the functionalization of metal�organic frameworks. chem rev ; : – . [ ] pullen s, fei h, orthaber a, et al. enhanced photochemical hydrogen production by a molecular diiron catalyst incorporated into a metal�organic framework. j am chem soc ; : – . [ ] sasan k, lin q, mao c, et al. incorporation of iron hydrogenase active sites into a highly stable metal�organic framework for photocatalytic hydrogen generation. chem commun ; : – . [ ] roy s, pascanu v, pullen s, et al. catalyst accessibility to chemical reductants in metal�organic frameworks. chem commun ; : – . [ ] wang w, song xw, hong z, et al. incorporation of iron hydrogenase active sites into a stable photosensitizing metal-organic framework for enhanced hydrogen production. appl catal b environ ; : . daofeng sun obtained his m.s. degree from liaocheng normal university, china in , and graduated from fujian institute of research on the structure of matter, chinese academy of sciences with a ph.d. degree under the supervision of rong cao and maochun hong in . after finishing three-year postdoctoral fellowship at miami university, he joined shandong university as a full professor in january , then moved to china university of petroleum (east china) in january . his current research interest focuses on the design and synthesis of porous materials for clean-energy, catalysis and environmental-related applications. http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h http://refhub.elsevier.com/s - ( ) - /h 	immobilizing [fefe]-hydrogenase mimics to metal–organic frameworks for enhanced hydrogen production 	conflict of interest 	references introduction the lahore journal of economics : (summer ): pp. – electricity consumption patterns: comparative evidence from pakistan’s public and private sectors karim khan,* anwar shah** and jaffar khan*** abstract this study examines the behavioral aspect of pakistan’s energy crisis by comparing electricity consumption in the public and private sectors. specifically, we compare consumption patterns of electricity across a sample of student hostels at two public sector universities and privately run student hostels. in addition, we collect household data for a sample of students at quaid-i-azam university (qau) in islamabad and compare their average electricity consumption with that of the public sector university hostels. we find that the latter’s average consumption of electricity is significantly higher than among private hostels and households. in assessing the moral hazard problem of the public sector in this context, we test the energy conservation behavior of qau students and the university administration. the results show that students are largely indifferent to conserving electricity, while the administration pays little attention to the use of energy-efficient lights and equipment. keywords: electricity consumption, public sector, private sector, moral hazard, conservation of electricity, organizational inefficiency. jel classification: h , d , d , d , d . . introduction pakistan’s severe energy crisis has prevented the economy from reaching its potential in recent years. at the same time, the demand for energy is increasing continuously. for instance, from to , the demand rose by almost percent per annum (kessides, ). this surge in demand has led to continuous growth in the gap between demand and supply over the last years. in may , the shortfall was estimated at , mw (national electric power regulatory authority, a, b). * assistant professor, pakistan institute of development economics, islamabad ** assistant professor, department of economics, quaid-i-azam university, islamabad. *** mphil student, department of economics, quaid-i-azam university, islamabad. see also http://tribune.com.pk/story/ /countrywide-energy-shortage-as-pepco-increases- loadshedding/ and http://www.theguardian.com/global-development/ /may/ /pakistan-energy- shortfall-coal-power-plants. karim khan, anwar shah and jaffar khan this declined slightly to , mw in june with the demand for power at , mw and power generation (supply) at , mw. however, the gap is still alarming. predictions for the near future indicate that the gap between demand and supply is likely to increase to , mw by and to , mw by (shahbaz, ). the energy crisis can be studied from two perspectives: the supply side and the demand side. the supply side incorporates issues related to the production and distribution of electricity. the demand side relates to the inefficient use of electricity, which in pakistan, is the dominant problem. according to ullah, khan and akhtar ( ), percent of the increase in energy intensity since was caused by the inefficient use of energy. this evidence is supplemented by the fact that pakistan lags far behind most developed and many developing countries in terms of efficiency. for instance, for each dollar of gdp, pakistan consumes percent more energy than india and percent more than the philippines. in addition, pakistan’s energy consumption per unit of gdp is fivefold that of the average for developed countries and twice that of the world average. the potential saving from the efficient use of energy in pakistan is estimated at percent or . million tons of oil- equivalent (mtoe), which would result in a percent reduction in net oil imports (pakistan energy sector taskforce, ). all these trends imply that pakistan has the potential to save electricity through demand- side measures, but has failed to do so thus far. at the global level, researchers and policymakers have paid special attention to the trends and dimensions of the energy crisis, including higher energy prices, the instability in the supply of different components, rapid energy depletion and global warming. while there is substantial research on energy problems in the context of pakistan, most studies have looked at changes in energy prices and their relation to economic growth, inflation and other macroeconomic indicators (see, for instance, jamil & ahmad, ; javid, javid & awan, ; shahbaz & feridun, ). to our knowledge, no original work has been carried out from a micro- perspective in pakistan. this study endeavors to initiate this angle by discussing the behavioral aspect of the demand for energy in pakistan. in particular, we are interested in examining whether electricity consumption behavior differs between the public and private sectors and, if so, why. in , the shortfall reached , mw for the first time. the pakistan ministry of planning, development and reform ( ) reported a peak shortfall of , mw on average as of july . the pakistan energy sector taskforce ( ) estimates that . mtoe (or . percent of the total energy consumed in the country) could potentially have been saved in the fiscal year alone. electricity consumption patterns in pakistan’s public and private sectors in order to support our hypothesis, we have collected data on the electricity consumption of two public sector universities and a sample of private hostels and households in islamabad. specifically, we compare the average consumption of electricity per capita between the university hostels and the private sector hostels and households. we find a significant difference in the consumption of electricity between the two sectors. the average consumption across the public sector hostels, however, is not significantly different. our findings support the hypothesis that public sector universities are characterized by inefficient energy use. we examine the behavioral aspect of this inefficiency based on a survey conducted at the quaid-i-azam university (qau) hostels, which documents the number of rooms left locked with electrical appliances still running. the results show that a significant number of students leave their rooms locked without having switched off the electrical appliances inside. this implies that, as consumers, students in the public sector are indifferent to the conservation of electricity. we have also collected data on the types of electrical lights used, which shows that little attention is paid to switching to energy-efficient devices at public sector universities. section describes the literature. sections and provide a theoretical background and methodology. section describes the data collected. section analyzes the results and section concludes the study. . a review of the literature the literature on the behavioral aspect of energy consumption focuses on three strands: users’ behavior at the institutional level, household behavior and the use of electricity-efficient appliances. the first strand includes considerable research asserting that the provision of free electricity in institutions makes people less likely to conserve electricity (see siero, bakker, dekker & van den burg, ; scherbaum, popovich & finlinson, ; zhang, wang & zhou, a, b, ). different factors shape such behavior. scherbaum et al. ( ) focus on individual-level factors, but find that the public environmental consciousness is an important predictor of personal environmental norms. these, in turn, affect self-reported energy-saving behavior at the workplace. in contrast, zhang et al. ( b, ) gauge the role of variables such as social and individual benefits, and the organization’s scherbaum et al. ( ) do not find any direct effect of the environmental worldview on self- reported energy-saving behavior. karim khan, anwar shah and jaffar khan own energy-saving norms. they suggest that environmental, personal and organizational benefits as well as the organization’s energy conservation patterns induce employees to conserve electricity. the second strand of the literature examines households’ energy- saving behavior. abrahamse, steg, vlek and rothengatter ( ) look at the effect of tailored information, tailored feedback and goal setting on energy consumption and saving behavior. they show that households that have been exposed to interventions save . percent in energy consumption compared to households in the control group, which saved only . percent. ek and söderholm ( ) argue that, in sweden, providing specific information on energy saving plays an important role in energy conservation. moreover, the willingness to save electricity differs by age group – retired people appear more willing to save than the average individual. in a similar study, brounen, kok and quigley ( ) examine the role of awareness and energy literacy in the behavior of dutch households. they find that households that are more aware of their energy consumption are also more efficient because they conserve and organize their energy consumption better. gyberg and palm ( ) show that information in the residential sector can help achieve sustainable energy systems and control excess demand for energy in people’s daily lives. other studies analyze the role of socio-demographic and economic variables. abrahamse and steg ( ) assert that family size and income have a significant effect on households’ direct and indirect energy consumption. wang, zhang, yin and zhang ( ) find that smaller expenditures, subsidized energy conservation, social norms and the experience of energy shortfalls enhance electricity-saving behavior among chinese households. however, the discomfort caused by energy- saving activities still has a negative effect on conservation behavior. see: barr, gilg and ford ( ); lindén, carlsson-kanyama and eriksson ( ); sardianou ( ); abrahamse, steg, gifford and vlek ( ); thøgersen and grønhøj ( ); martinsson, lundqvist and sundström ( ). feng, sovacool and vu ( ) argue that economic benefits and awareness play an important role in energy conservation. abrahamse and steg ( ) find that, among dutch households, socio-demographic variables are more important than psychological variables in determining energy consumption. the other control they use – similar to the level of education, income and gender – has no impact on people’s willingness to reduce electricity consumption. electricity consumption patterns in pakistan’s public and private sectors the third strand of the literature focuses on the use of electricity- efficient appliances (including lights, air conditioners, washing machines, refrigerators, tv sets, etc.). guan, mills and zhang ( ) examine the problems and prospects of energy-efficient lighting in china. they find that lack of awareness, the cost-effectiveness of power efficiency projects, primitive manufacturing processes and strong incentives to export energy-efficient products constrain the local use of efficient lighting. government policies also have an impact on the adoption of energy-efficient appliances. ma, andrews-speed and zhang ( ) find that energy-efficient appliances and the government’s energy efficiency polices have positive implications for energy conservation in china. accordingly, they suggest that energy conservation can be enhanced by subsidizing and promoting the use of energy-efficient appliances. ma, andrews-speed and zhang ( ) find that households prefer comfort and convenience over energy conservation, but that this behavior can be changed through economic incentives such as charging higher prices for electricity or offering discounts on the use of energy-efficient appliances. . theoretical framework our starting point is the standard classification of goods shown in table , which divides goods in a society into four categories. private goods are competed for, that is, individuals can be excluded from their use. common property resources are defined by two characteristics: it is difficult to exclude users and the use of the good by one user diminishes the benefits available to other users. nonrival goods from which users can be readily excluded (the opposite of common property resources) are called “spite goods” because this exclusion does not enhance welfare. common property resources are similar to public goods in that user exclusion is difficult, but they are also similar to private goods in that users must compete for them. by contrast, public goods can neither exclude users nor are users compelled to compete for them. table : a taxonomy of goods rival nonrival excludable private goods spite goods nonexcludable common property public goods source: bowles ( ). examples include collecting a toll on a little-used highway or charging for admission to an uncrowded museum. karim khan, anwar shah and jaffar khan in most pakistani public sector universities, the consumption of electricity is divided into three categories of use: (i) the electricity that is used in common areas such as classrooms, libraries, laboratories and public access routes, (ii) the consumption of electricity specifically by employees in offices, and (iii) the electricity used by students in residence. in the first category, the consumption is paid for by the university as public university fees are subsidized, that is, electricity is a “public” good. this means that employees and students do not pay for the electricity they consume during working or class hours. hence, it is likely that, in the absence of moral responsibility and the positive marginal cost of an extra unit of electricity, students and employees will be indifferent to whether their electricity consumption is efficient. similarly, in the third case, there is the probability of moral hazard with regard to electricity consumption. in contrast, private hostels are run for profit and, as a consequence, resident students are fully liable for the costs they incur. as profit-maximizing agents, hostel owners will do their best to reduce their running costs, for instance, by monitoring the unnecessary or overuse of electricity. moreover, the profit motive may induce them to use electricity-efficient appliances to reduce costs. all these factors will ensure the optimal consumption of electricity in private hostels. in the same way, households are fully liable for the cost of the electricity they consume. as neoclassical economic agents, they will equate their marginal cost of electricity with the marginal benefit of consumption. this is their incentive to avoid overuse and to use electricity-efficient appliances in their homes. based on this discussion, we hypothesize that the consumption of electricity is inefficient in the public sector compared to the private sector. there are three justifications for this hypothesis. first, in the public sector, the marginal cost of using an additional unit of electricity is while the marginal benefit is positive. this implies a higher level of average consumption in public sector university hostels than in private hostels and households. second, the cost of electricity to individuals in the public sector is hidden and, therefore, we expect they will not bother to avoid using extra electricity. third, in the public sector in pakistan, there is no formal or informal punishment mechanism for the misuse of electricity, which significantly reduces the transaction cost associated with any misuse. universities are financed mainly by the federal government through the higher education commission. in particular, this payment must ensure that hostel owners have profit rates as an incentive. for a detailed discussion, see stern and gardner ( ); stern ( ); howard ( ). electricity consumption patterns in pakistan’s public and private sectors . methodology we carry out a comparative analysis of the public and private sectors by using two public sector universities – qau in islamabad and the university of baluchistan in quetta – as case studies. we have collected electricity consumption data for the university hostels, private hostels in islamabad and the households of a sample of qau students. in comparing the data for the public sector and the private sector, we expect a significant difference in consumption patterns. next, we investigate the behavioral causes for this difference. in particular, we are interested in showing that users in the public sector are indifferent to the conservation of electricity. for this purpose, we conduct two types of behavioral observations. first, we survey the qau hostels to determine how many rooms are left locked but with the lights inside switched on. we expect this to be the case for a significant number of rooms. second, we compare the types of electrical appliances used in both sectors. again, we expect private sector users to be more concerned about electricity-efficient appliances than public sector users. . collection and characteristics of data the data for the two universities’ electricity consumption was obtained from their monthly bills, to access which we submitted a formal application to the relevant department at each university. we also asked for information on the number of students and staff and the types of lighting used in each block. next, we noted down the -digit reference number on the bill (see table a in the appendix for details) and used it to download the user’s annual billing data for and from the district electrical supply company’s website. for a comparative analysis, we calculated the per capita electricity consumed in units (the total number of consumed units divided by the number of actual users). as table a in the appendix shows, qau has nine hostels, five annexes and six student residences. collectively, these comprise , rooms, including accommodation for both men and women. qau has we needed the number of students and staff that actually consumed electricity in each block in order to find the per capita consumption of electricity. the enumerator also counted the number of each type of light in each block. per capita consumption of electricity can also be measured in monetary terms. however, electricity companies in pakistan charge progressively higher rates for different units of electricity consumed, which makes the monetary measure impractical for analytical comparison. alternatively, our measure of the per capita consumption of electricity is independent of pricing policies. karim khan, anwar shah and jaffar khan approximately , students, around percent of who live in its hostels. the university of baluchistan has around , students and hostels, one of which is for women. around , students live in these hostels, which comes to almost percent of the total student population. the second sample comprises privately run hostels in islamabad. the data collected included the -digit reference number obtained from each hostel owner’s electricity bill, the total number of resident students, and the types and number of lights used in each case. informal discussions revealed that these hostels are administered primarily by the owners, which implies that it is in their interest to monitor the use of electricity. finally, the household data on electricity consumption was collected through a questionnaire distributed among a random sample of qau students living at the university hostels (see appendix). among other information, they were asked to record their -digit electricity bill reference number and the total number of energy savers, tube-lights, bulbs, air conditioners, etc., used in their homes. based on this information, we used the reference numbers to download each user’s billing data and recorded the total number of units consumed by each household. the data represents households across districts in pakistan. of almost questionnaires distributed, only were completed and returned. after accounting for those with missing information, the net number of usable questionnaires dropped to . . empirical evidence the empirical findings are based on a comparison of electricity consumption across the public and private sectors, and a behavioral explanation for the differences observed. . . comparative analysis of public and private sector consumption table summarizes the electricity consumption data collected from the two universities and the private sector hostels and households. the average monthly consumption per student ranges from . to . units in the qau hostels (or . and if we remove the outlier). in contrast, the average monthly consumption per student ranges from . to . units in the private hostels. the level of energy consumed at the data was collected from a sample of undergraduate, graduate and doctoral students. although the questionnaire was also distributed among the women’s hostels, the response rate there was low. electricity consumption patterns in pakistan’s public and private sectors the qau hostels is significantly higher than that consumed at the private sector hostels (p < . ). both types of hostels offer a similar level of services, which implies that the public sector hostels use energy less efficiently because they consume more while providing the same services. this characterizes the problem of moral hazard, where the findings indicate that students misuse or overuse electricity in the public sector. table : comparative electricity consumption a. public sector hostel name average consumption per month in units total number of students average monthly consumption per student in units qau hostel # , . hostel # , . hostel # , . hostel # , . hostel # , . hostel # , . hostel # , . hostel # , . hostel # , . three annexes , . c- . c- . c- . c- . c- . c- . university of baluchistan hostel blocks – , , . hostel block , . girls’ hostel , . continued… this p-value is the corresponding value of the t-statistic of unequal means while using the monthly consumption per student as the observation. see the simple regression for statistical inference in table , in which the dummy for the public sector is highly significant. in islamabad, most private hostels offer services such as hot water in winter, cold water in summer, a fan in the room, a regular water supply and ironing facilities, etc. qau offers the same services. karim khan, anwar shah and jaffar khan table : comparative electricity consumption (continued...) b. private sector hostel name average consumption per month in units total number of students average monthly consumption per student in units ali . bilal . chughtai . danish , . ehsan . fasal . ghazi . haris . idrees . jamsheed . kurram , . liaqat . moeen . nashaad . owais . perooz . c. household data category sum of average monthly consumption total number of individuals in household average monthly consumption per person lowest % , . . second lowest % , . . second highest % , . . highest % , . . notes: average monthly consumption = total annual consumption in a typical year / . average monthly consumption per student = average monthly consumption of hostel / number of resident students. total number of households = , divided into four quartiles based on average monthly consumption of electricity. average monthly consumption per person for each quartile = sum of average monthly consumption by all households in that quartile / total number of household members in that quartile. source: authors’ calculations. in order to check the robustness of this result, we analyze the data for another public sector university, the university of baluchistan, and the sample of private households. table shows that the average monthly consumption of electricity per student in the university’s hostels the household data survey was conducted at qau (see the questionnaire in the appendix for details). electricity consumption patterns in pakistan’s public and private sectors is not very different from that of the qau hostels. this indicates that students’ energy use behavior is similar across the two public sector universities. a comparison with the household sample shows that average consumption in the public sector is greater. to check for the effects of outliers, we compare the average monthly consumption per person across all four types of consumers for a typical year. as figure shows, in most months (except august and september), the consumption per student at qau is greater than that of the private hostels. however, given that universities are closed in the summer, it is not suitable to compare the average consumption in these months. in spite of this effect, the t-test of unequal variances shows a significant difference in the electricity consumption of the two types of hostels (p < . ). this anomaly is not robust with regard to the university of baluchistan, where the average monthly consumption is larger than that of the private hostels all year round. figure : comparative electricity use per student in public sector and private sector hostels similarly, if we compare the average consumption of electricity at qau with the average consumption of the household sample, we find that the university consumes more energy than the households in all months except august and september. however, the households consume more electricity in the summer when the use of electrical this, in turn, allows us to counter any billing errors on the part of the electricity company or the effect of an individual hostel that may be an outlier. the regulations for running private hostels are not well enforced in pakistan. it is possible that they are used for other purposes during the summer holidays, but we have no data to confirm this. units months qau hostels private hostels ub hostels households karim khan, anwar shah and jaffar khan appliances such as exhaust fans, air conditioners and refrigerators increases. in comparison, the qau hostels are usually closed during the summer. again, this result is not robust with respect to the university of baluchistan, which consumes more electricity per student than the households all year round. the highest level of average consumption at qau falls in january, possibly because students use nontraditional means of heating during the peak of winter. however, if this is the case, it has an important behavioral policy implication: permitting students to use individual heaters or providing a centralized heating system might address the moral hazard problem of electricity consumption. the relatively low consumption per student during july, august and september reflects that the qau hostels are closed, although this pattern does not emerge for the university of baluchistan hostels. we apply the mann–whitney u test for a paired comparison of per person consumption across all types of consumers. as table shows, qau’s average monthly consumption of electricity is significantly different from that of the private hostels and households; the same holds for average consumption at the university of baluchistan. the average consumption of the two universities, however, is similar. table : results of mann–whitney u test comparison p-value qau hostels vs. private hostels . *** qau hostels vs. households . ** university of baluchistan hostels vs. private hostels . *** university of baluchistan hostels vs. households . *** qau hostels vs. university of baluchistan hostels . note: *** p < . and ** p < . . source: authors’ calculations. the results imply that (i) electricity user behavior in the public sector is different from that of the private sector, and (ii) public sector organizations do not show any significant difference in their electricity use behavior. table confirms this finding, using a dummy variable for the public sector in a simple regression. university hostels in pakistan tend not to be heated in the winters and the use of individual heaters is not allowed. however, in the absence of administrative monitoring, students often use individual heaters. electricity consumption patterns in pakistan’s public and private sectors table : simple regression results dependent variable = per person electricity consumption intercept . *** public sector dummy . *** r . note: *** p < . . source: authors’ calculations. . . behavioral explanation for differences in public and private sectors this section analyzes the misuse of electricity by end-users and explains in part organizational inefficiency as far as the use of electricity- efficient appliances is concerned. . . . misuse of electricity in qau hostels table gives the results of the survey documenting the misuse of electricity in the qau hostels. one indicator of students’ conservation behavior is whether or not they switch off the lights in their room when leaving. this is measured by the number of rooms left locked with the lights inside switched on. the survey was carried out at three different times: from to , from to , and from to hours. the three survey rounds were conducted on three different days. karim khan, anwar shah and jaffar khan t a b le : m is u se o f e le ct ri ci ty i n q a u h o st e ls h o st e l n a m e n o . o f ro o m s f ir st s u rv e y t o s e co n d s u rv e y t o t h ir d s u rv e y t o m is u se % a cr o ss t h re e su rv e y s l o ck e d ro o m s l ig h ts o n m is u se % l o ck e d ro o m s l ig h ts o n m is u se % l o ck e d ro o m s l ig h ts o n m is u se % h o st e l # . . . . h o st e l # . . . . h o st e l # . . . . h o st e l # . . . . h o st e l # . . . . h o st e l # . . . . h o st e l # . . . . h o st e l # . . . . h o st e l # . . . . f iv e a n n e x e s . . . . s ix c -t y p e h o st e ls . . . . a v e ra g e o f a ll h o st e ls . . . . s o u rc e: a u th o rs ’ ca lc u la ti o n s. electricity consumption patterns in pakistan’s public and private sectors in the first two survey periods, almost percent of the hostel rooms were left locked with the lights inside switched on. this decreases to around percent in the third survey round, which may be because most students remain in their rooms in the evening. hostels , and and the c- type hostels are women’s hostels. we find no difference in the misuse of electricity where gender is concerned. most students also tended to leave their fans switched on, but we did not collect data on this. thus, students’ indifference to saving electricity might partly explain the higher average consumption at qau relative to the private hostels and households. . . . organizational inefficiency in the selection of electrical equipment in addition to consumer inefficiency, there is also organizational inefficiency in the public sector to consider. table compares the use of electricity-efficient lights across the public and private sectors. table : comparative use of efficient lighting appliances in public and private sectors lighting appliance qau hostels private hostels households no. as % of total no. as % of total no. as % of total tube-lights , . . . bulbs . . . energy savers . . , . total , . . , . source: authors’ calculations. clearly, there is a considerable difference in the use of energy- efficient appliances in the two sectors. the private sector uses relatively more energy-efficient appliances than the public sector. out of a total of , large and small lights installed at qau, the number of tube-lights is , ( . percent), the number of bulbs is ( . percent) and the number of energy savers is merely ( . percent). in comparison, the percentage of energy savers installed in the private hostels and households is and . percent, respectively. this shows that using energy-efficient appliances is still a low priority in the public sector compared to the private sector; it also reflects qau’s organizational inefficiency in this context. karim khan, anwar shah and jaffar khan . conclusion this study was motivated by the literature on the moral hazard and “free rider” problems associated with public goods. based on this argument, we compare the consumption patterns of electricity across the public and private sectors, using a sample of public sector university hostels and privately run hostels to represent the two sectors. we also conduct a short survey to compare the average energy consumption of public sector hostels and households. finally, we analyze the behavioral causes of the inefficiency that emerges – both on the part of users and the university administration – in the public sector. there are three main findings of this study. first, the average consumption of electricity per capita in the public sector is significantly higher than in the private sector, including both the private hostels and households. this result is robust with respect to different organizations in the public sector (qau and the university of baluchistan). this has an important policy implication, given pakistan’s energy crisis. in order to offset the rising demand for electricity through conservation, policymakers must focus on the public sector. a twofold strategy is needed to enhance organizational efficiency in terms of monitoring the use of electricity, and addressing consumer behavior by developing norms that discourage the misuse of electricity. employing both formal and informal institutional structures can help control the moral hazard associated with the misuse of electricity in the public sector. second, the survey finding that almost percent of hostel rooms at qau are left locked with the lights inside switched on implies considerable indifference to energy conservation among students. we recommend devising an efficient monitoring and punishment mechanism to discourage this consumption behavior at public sector institutions. finally, we find that the use of energy-efficient lighting in the public sector is a negligible . percent relative to percent in private hostels and over percent in the households sampled. this implies that the organizational structure at public sector institutions is significantly inefficient with regard to the use of energy savers. expanding the scale at which energy-efficient appliances are used in this sector would help conserve electricity. however, future research is needed in this area to provide clear guidelines for overcoming the energy crisis. electricity consumption patterns in pakistan’s public and private sectors references abrahamse, w., & steg, l. 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( ). determinants of employee electricity saving: the role of social benefits, personal benefits and organizational electricity saving climate. journal of cleaner production, , – . electricity consumption patterns in pakistan’s public and private sectors appendix table a : hostel reference numbers and addresses public sector hostels reference no. qau hostel # - - hostel # - - hostel # - - hostel # - - hostel # - - hostel # - - hostel # - - hostel # - - hostel # - - women’s annex - - men’s annex - - women’s annex h- - - c- (women’s hostel) - - c- (women’s hostel) - - c- (women’s hostel) - - c- (women’s hostel) - - c- (women’s hostel) - - c- (women’s hostel) - - university of baluchistan hostel blocks – hostel block women’s hostel karim khan, anwar shah and jaffar khan private sector hostels reference no. main murree road, barakho, islamabad ali - - bilal - - chughtai - - danish - - ehsan - - fasal - - ghazi - - haris - - idrees - - sector f- , islamabad jamsheed - - chatta bakhtawar, chak shahzad, islamabad kurram - - liaqat - - moeen - - nashaad - - owais - - perooz - - electricity consumption patterns in pakistan’s public and private sectors survey questionnaire dear respondent, assalam-o-alaikum, this questionnaire aims to collect information on the electricity consumption of households. you are requested to spare the time to answer all the questions below to the best of your knowledge. your cooperation will enable us to explore various dimensions of the current electricity crisis. the data will be used for research at the mphil level at the school of economics at quaid-i-azam university, islamabad. thank you in advance for your cooperation. mphil scholar personal information age: level of education: mphil/phd/msc/ba/fsc/matric/below matric gender: male/female district: household information family structure: joint/nuclear where do you live? official house/own house/rented/other total number of family members: below years: between and years: above years: total number of males: total number of females: karim khan, anwar shah and jaffar khan house constructed: year ago/ years ago/ years ago/ years ago/more than years ago total number of rooms: total number of energy savers: total number of tube-lights: total number of bulbs: total number of air-conditioners (if any): does your family receive an electricity bill regularly? yes/no please write down the -digit reference number of the electricity bill: please tick the relevant answer to the following questions: my family is aware of energy-saving appliances. yes/no/don’t know my family members turn off the lights when there is bright sunlight. yes/no/don’t know all my family members know that conserving electricity decreases expenditure. yes/no/don’t know the elders in my family encourage electricity saving. yes/no/don’t know do you think students conserve electricity at qau in the same way they would at home? yes/no/don’t know this may be the author’s version of a work that was submitted/accepted for publication in the following source: motta, nunzio ( ) nanostructures for sensors, electronics, energy and environment ii. beilstein journal of nanotechnology, , pp. - . this file was downloaded from: https://eprints.qut.edu.au/ / c© consult author(s) regarding copyright matters this work is covered by copyright. unless the document is being made available under a creative commons licence, you must assume that re-use is limited to personal use and that permission from the copyright owner must be obtained for all other uses. if the docu- ment is available under a creative commons license (or other specified license) then refer to the licence for details of permitted re-use. it is a condition of access that users recog- nise and abide by the legal requirements associated with these rights. if you believe that this work infringes copyright please provide details by email to qut.copyright@qut.edu.au license: creative commons: attribution . notice: please note that this document may not 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series "nanostructures for sensors, electronics, energy and environment ii". guest editor: n. motta © motta; licensee beilstein-institut. license and terms: see end of document. this thematic series, “nanostructures for sensors, electronics, energy and environment ii”, is a continuation of the series re- leased three years ago and again presents articles in this highly dynamic field. the fields of nanoscale science and technology are rapidly emerging, with a focus on the design, fabrication, and characterization of functional objects. the existing energy crisis could be mediated not only by new and more efficient methods of collecting sunlight, but also by saving resources by applying developments in storage, electronics and sensors. conventional energy sources are limited and most of them generate greenhouse gases that pollute the environment. photo- voltaic technology is a potentially viable solution to produce clean energy; however, its production costs are still too high due to the materials and process techniques involved. moreover, because the sun is an intermittent energy source, the further development of energy storage systems is necessary in order to allow photovoltaic-based power generation to be independent from the grid. carbon, one of the most abundant materials found on earth, is the key atomic species in the compounds responsible for green- house gas emission and pollution. however, it can also be used to offset these effects, acting as a valuable material for energy generation, storage, carbon sequestration [ ] and sensing [ , ]. carbon can be employed in one or more of its allotrope forms (e.g., graphene, carbon nanotubes, fullerene) in devices such as organic and inorganic solar cells and supercapacitors [ ]. these devices can be produced in large quantities with inexpensive synthesis and process methods based on printing and roll-to-roll techniques, establishing the basis of a new green technology. currently, most of the research effort in the field is focused on the synthesis of large quantities of high quality carbon nanoma- terials in order to use them for industrial scale production of energy generation and storage devices. however, other interest- ing advances are appearing and are covered in this series. graphene and graphene oxide exhibit interesting properties that can be exploited in room temperature gas sensing devices. the plasmonic effect, generated by the inclusion of metallic nanoparticles, can be used to overcome certain limitations of the carbon materials, especially in organic solar cells [ ]. http://www.beilstein-journals.org/bjnano/about/openaccess.htm mailto:n.motta@qut.edu.au http://dx.doi.org/ . % fbjnano. . beilstein j. nanotechnol. , , – . the optical properties of nanomaterials can also be exploited to produce new, powerful devices such as nanolasers, light emit- ting devices [ ] and optical nanosensors. nanomaterials continue to intrigue researchers with new prop- erties discovered every year in such low dimensional structures, generating an incredible field of basic and applied research with the expectation of achieving a better, cleaner and more sustain- able world. nunzio motta brisbane, september references . de silva, s. w.; du, a.; senadeera, w.; gu, y. beilstein j. nanotechnol. , , – . doi: . /bjnano. . . piloto, c.; notarianni, m.; shafiei, m.; taran, e.; galpaya, d.; yan, c.; motta, n. beilstein j. nanotechnol. , , – . doi: . /bjnano. . . li, d.; pang, z.; chen, x.; luo, l.; cai, y.; wei, q. beilstein j. nanotechnol. , , – . doi: . /bjnano. . . liu, j.; mirri, f.; notarianni, m.; pasquali, m.; motta, n. j. power sources , , – . doi: . /j.jpowsour. . . . notarianni, m.; vernon, k.; chou, a.; liu, j.; motta, n. adv. device mater. , , – . doi: . / y. . liu, j.; notarianni, m.; rintoul, l.; motta, n. beilstein j. nanotechnol. , , – . doi: . /bjnano. . license and terms this is an open access article under the terms of the creative commons attribution license (http://creativecommons.org/licenses/by/ . ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. the license is subject to the beilstein journal of nanotechnology terms and conditions: (http://www.beilstein-journals.org/bjnano) the definitive version of this article is the electronic one which can be found at: doi: . /bjnano. . http://dx.doi.org/ . % fbjnano. . http://dx.doi.org/ . % fbjnano. . http://dx.doi.org/ . % fbjnano. . http://dx.doi.org/ . % fj.jpowsour. . . http://dx.doi.org/ . % f y. http://dx.doi.org/ . % fbjnano. . http://creativecommons.org/licenses/by/ . http://www.beilstein-journals.org/bjnano http://dx.doi.org/ . % fbjnano. . 	references . .j.ijrse. . international journal of renewable and sustainable energy ; ( ): - published online november , (http://www.sciencepublishinggroup.com/j/ijrse) doi: . /j.ijrse. . energy demand & prospect of geothermal energy as the solution of energy crisis of bangladesh – an approach to green energy solution a. s. m. monjurul hasan ,* , md habibullah , khaza newaz muhammad , mohammad walid bin siraj , md ahsan kabir , a. s. m. muhaiminul hasan department of electrical & electronic engineering, iut, dhaka, bangladesh department of computer science & engineering, iut, dhaka, bangladesh department of electrical & electronic engineering, fatih university, turkey department of electrical & electronic engineering, aust, dhaka, bangladesh email address: a.s.m.monjurul.hasan@hotmail.com(a. s. m. m. hasan) to cite this article: a. s. m. monjurul hasan, md habibullah, khaza newaz muhammad, mohammad walid bin siraj, md ahsan kabir, a. s. m. muhaiminul hasan. energy demand & prospect of geothermal energy as the solution of energy crisis of bangladesh – an approach to green energy solution. international journal of renewable and sustainable energy. vol. , no. , , pp. - . doi: . /j.ijrse. . abstract: bangladesh has among the lowest per capita energy ( kg oil equivalents) consumption in the world and is severely dependent on additional environmentally friendly renewable energy resources in the future. among the possible energy resources that could be explored is the potential geothermal energy in regions of higher geothermal gradients with favorable geo-tectonic setting and ideal petro-physical properties. a preliminary examination of bottom hole temperatures of a large number of on-shore wells spread over a vast area in the eastern part of the country, especially in thakurgaon-mymensingh-sunamgonj-sylhet through in the bengal fore deep, strongly suggests that several other areas are of great interest for further studies in order to determine their geothermal energy potential. bangladesh has witnessed a high demand for uninterrupted electricity due to rapid civilization in the last few years. bangladesh needs now a reliable green energy sources as its power sector beset by many infrastructural problems (inefficient transmission system, very old power stations and cumbersome decision making process). bangladesh has taken initiative to generate mw electricity within . in this regard, geothermal energy can be a viable and useful alternative and this paper proposes the prospects of its introduction to the power sector of bangladesh. in this paper, a study is presented that shows the suitable locations in bangladesh where geothermal power plants can be set up easily. recently, the ministry of power, energy and mineral resources has approved the establishment of the first ever geothermal power plant ( mw) in the country. a total of approximately mw can be added into the energy grid of bangladesh through geothermal power systems. the geothermal energy is green, indigenous, locally occurring and continuously available independent of climatic changes. it will help to reduce the huge oil bill that the country is facing now, provided the national planners give adequate attention and support for the development of geothermal energy at a rapid pace to reduce the severe electricity crisis in bangladesh as other energy resources like peat, hydropower, nuclear, wind, tidal / waves are not significant at present. keywords: geothermal power system, surface temperature, tectonic-structural region, renewable energy . introduction bangladesh has the eighth largest world population of about million in a small territory of , sq. km having the highest demographic density in this planet. about % of the rural population has very limited access to conventional energy sources like gas, coal and electricity. they are mainly dependent on kerosene oil for lighting and biomass for cooking and for meeting other needs. the national energy policy is aimed at providing electricity to majority of rural people by . presently, electricity is mainly generated by natural gas, the principal nonrenewable energy resource of the country. the daily production of gas is . mmscfd per day of which presently % is consumed for power generation and % is used for a. s. m. monjurul hasan et al.: energy demand & prospect of geothermal energy as the solution of energy crisis of bangladesh – an approach to green energy solution production of fertilizer. besides, domestic, commercial and industrial consumers use %. the eastern half of the country has gas network and is the principal beneficiary. there are two distinct patterns of use of energy resources for power generation in the eastern and western zones-gas and hydropower resources in the eastern zone and oil (naphtha and diesel) and gas in the western zone while coal is yet to become a resource in near future. among the renewable energy resources - wind power is almost non-existent. waves, currents and tidal sources have little promise here. only geothermal energy can emerge as the single largest and sustainable energy resources of bangladesh especially in rural areas provided the abandoned dry on-shore wells drilled for petroleum exploration are utilized for the purpose. . geographical information bangladesh, a tropical to subtropical country, is located in the northeast part of south asia between ° ′ and ° ′ north latitude and ° ′ and ° ′ east longitude. bangladesh, with its million people in a land mass of , km , is one of the most densely populated countries in the world with % of its population living in rural areas. india surrounds the country on three sides (west, north and east), sharing . km of a common border; myanmar shares a mountainous border in the southeast; altogether this constitutes % of the borderline. figure . location map of bangladesh and surroundings the bay of bengal is open to the south. the coastal zone of bangladesh consists of about km coastline, the largest patch of a natural mangrove forest shared with india and a long sea beach along the southeast coast. three major types of landscapes are found in bangladesh: floodplains ( %), terraces ( %), and hills ( %). excepting the eastern hilly region, almost all of the country lies in the active delta of three of the world’s major rivers: the ganges, the brahmaputra, and the meghna (gbm). the water ecosystem of the country comprises the tributaries and distributaries of these major rivers and numerous perennial and seasonal wetlands like haors, baors and beels. huge amounts of rainfall runoff occur in the entire gbm catchments during the monsoon season (june-october), while in the dry period the country suffers from severe moisture. . energy scenario of bangladesh bangladesh, considered a developing economy with a recorded gdp growth of above % during the last few years, is one of the energy starved countries of the world. by some estimates, a gdp growth rate of - % is forgone annually because of a shortage of energy and lower power generation. a major portion of energy is consumed for subsistence (e.g. cooking, lighting, heating, etc.) and only a small portion is used for economic growth (e.g. agriculture, industry, transport, commerce, etc.). table . power generation of bangladesh responsible department generation capacity (mw) sub total percentage total generati on bpdb mw % of total generation mw apscl egcb rpcl ipps mw % of total generation sipps(bpdb) years rental / years rental quick rental sipps(reb) figure . fuel type generation capacity according to bangladesh power development board (july, ) from figure we can see the fuel type generation of electricity. natural gas plays the main role in bangladesh for generating electricity. recently furnace oil are been used massively in quick rental power plants. international journal of renewable and sustainable energy ; ( ): - . renewable energy scenario of bangladesh efficient utilization of renewable energy resources in bangladesh has yet to obtain commercial dimensions and cannot serve as an alternative to conventional energy resources. however, they can serve to supplement the long term energy needs of bangladesh to a significant level. harnessing these resources appears to be a promising solution for improving the quality of life of rural villagers. categories of renewable energy that are being used in limited ways in the country are hydro-, solar and wind power, bio-gas, and biomass such as wood, rice husks, etc. the present share of renewable energy is around %. at present, the national capacity of renewable energy based power, excepting hydro-power, is approx. mw as shown in table . micro-hydro and mini-hydro, however, have limited potential in bangladesh. considering the fuel crisis, and exploring new, safe, and sustainable energy resources, the government has taken various steps to promote energy conservation and the use of renewable sources. government of bangladesh declared the renewable energy policy, in effect since (memr, ). according to this policy, the government is committed to facilitating both public and private sector investment in renewable energy projects to scale up contributions of existing renewable energy based electricity production. table . renewable energy scenario of bangladesh category generation shs mw mw other solar pv applications mw wind energy mw biomass based electricity < mw biogas based electricity mw total mw . tectonic & geological settings the neogene (figure ) sedimentary sequence penetrated in the bangladesh part of the bengal basin (figure ) are represented by alternating beds of sandstones, siltstone, shales and claystones with occasional conglomerate bands of varying thickness. here, the arenaceous sediments with porosity ranging from to percent of sufficient permeability are the reservoir rocks, while the argillaceous beds will act as cap rock for preventing the loss of geothermal heat from the sandy reservoir beds. the sedimentary column in the platform flank as well as the eastern folded belt of bengal foredeep attain colossal thickness of about km as revealed in the aero-magnetic and deep seismic surveys as well as very deep drilling data, (guha and bakhtine ) as evident in the regional tectonic setting of bangladesh (figure ). figure . geological map of bangladesh figure . regional geo tectonic setting of bangladesh on the other hand in the shelf area rangpur saddle forms the apex of the garo-rajmahal gap where the pre- cambriam basement is represented by diorite, granodiorite, granite and pegmatite along with gneisses and schists, which are blanketed by only ca m of pliocene dupi tila sandstone, followed by about m pliestocene madhuput clays and to m holocene deposits (guha ). permian gondwana coal deposits (sub-bituminous) occur in the shallow faulted basement grabens at a number of places like barapukuria, khalashpir, phulbari, dighirpar etc. as evident from local small negative gravity anomalies (petrobangla ). the first two underground mines at barapukuria (coal) and madhyapara (hard rock) are facing with unforeseen problems of water flooding specially barapukuria, which upset the target by many years. the fate of the mw thermal power plant at barapukuria mine head has become uncertain although the infrastructure has already been developed. from rangpur saddle (figure ) the basement dips gently first towards north-west along the dinajpur slope and then a. s. m. monjurul hasan et al.: energy demand & prospect of geothermal energy as the solution of energy crisis of bangladesh – an approach to green energy solution steeply towards the sub - himalayan foredeep and the basement attains the depth of m at shalbonhat well located on the north-western most tip of bangladesh (tetulia). the basement dips very gently ( to degrees) towards southeast along the bogra slope, as evident in sequence stratigraphy on the surface of the eocene sylhet / bogra limestone until the hinge zone, where dips gets steeper, to degrees (guha ). the cretaceous rajmahal trap formed by upwelling of plastic basalt flow along the fissures at rajmahal, bihar (india), is only about km west of rajshahi border, which was encountered in deep wells to the east as far as singra and kutchma located about km east of rajmahal. this basalt trap is known as sylhet trap that occurs also in meghalaya (india). further east and to the north of sylhet (guha ), trap occurs which also can be a cap-rock to prevent escape of geothermal energy from the potential reservoir beds. in the hinge zone the ecocene limestone attains the depth of - km as can be seen in the seismic profiles. figure . tectonic framework of bangladesh with fold axes . geothermal energy geothermal energy is the energy contained in the heated rocks and fluid that fills the fractures and pores within the earth's crust. it originates from radioactive decay deep within the earth and can exist as hot water, steam, or hot dry rocks. geothermal (meaning “earth heat”) energy involves using the high temperatures produced beneath the earth to generate electricity from heated water, as well as for various direct uses (such as hot springs spas, lumber drying or aquaculture). the term geothermal is also applied to the temperatures of the earth near the surface which are used as a source of consistent temperatures for heating and cooling of buildings. geothermal applications that involve water heated within the earth are also called hydrothermal processes. bangladesh occupies the central part of the bengal basin, the largest sedimentary basin of the world with thickness of the sedimentary column above the pre-cambrian basement of about km at the axis of the trough the sedimentary column east of the hinge zone consists of alternation of porous and permeable sandstones of reasonable thickness with argillaceous clays and shales. the sandstone will be the reservoir for geothermal fluids with sufficient in flow while shales and clays will acts as impervious layers for retaining the geothermal heat within the reservoir for effective use. the rajmahal / sylhet traps of cretaceous basaltic flows encountered in wells in the rajshahi division west of the hinge zone will also be a good cap rock for retaining the geothermal energy resources there, as evident elsewhere. a study of bottom hole temperature (bht) of deep wells drilled for petroleum exploration in northeastern part of bangladesh show very encouraging results (khandoker and haque ). the isothermic contours generally follow the bouguer anomaly map pattern (petrobangla ). the isothermal pattern represents an oval shaped basin with nne-ssw trend with temperature decreasing from the rim towards the center of the trough. a local high and a low could be seen within the broad trough in the northeast, the high represented by an anticlinal high (sylhet – dupi tila) and low formed by goyine-kushiara syncline. the bouguer anomaly contours vary from - mgal in the marginal part to more than - mgal in the central part of the trough. it is evident from the bht that the geothermal temperature is sufficiently high, to oc, to generate electricity at depth from to . km when the geothermal water is taken to the surface through drill holes. table . geothermal gradients as noted in some deep wells of bangladesh well name depth (km) gradient (k/km) hazipur , , bakhrabad , , titas , , habigonj , , rashidpur , , biani bazar , , kailas tila , , sylhet , , chhatak , , semutang , , begamganj , , . area of prime interest recently, the ministry of power, energy and mineral resources has approved the establishment of the first ever geothermal power plant ( mw) in the country. a dhaka based private company named anglo mgh energy has initiated this project at saland of thakurgaon district. the rangpur saddle, bogra shelf potentially offers good international journal of renewable and sustainable energy ; ( ): - conditions for geothermal power projects. although the cost of setting up a geothermal power plant is high due to the high cost of drill-ing wells, it can be reduced by using the abandoned on-shore dry wells which have sufficient high temperature gradient (like over k/km). figure . geotectonic map of northwest bangladesh . conclusion with the demand for electricity in bangladesh increasing every day, potential energy sources need to be sought out in order to alleviate the ensuing energy crisis. as bangladesh is also a developing country, it has to be borne in mind that these energy sources have to be inexpensive, preferably local and can be quickly setup for power generation. although solar, wind and hydropower offer interesting alternatives they require huge funding, which would strain the economy. this paper looks into the prospect of geothermal energy in bangladesh and where in the country, there is suitable infrastructure for its implementation. geothermal power satisfies the criteria for a suitable energy system for bangladesh, and if our government deploys this energy source, it would be a giant leap forward in solving the present energy crisis of the nation. acknowledgements authors are grateful to prof. dr. a. k. m. sadrul islam, department of mechanical & chemical engineering, & assistant professor syeed shihav, department of electrical & electronic engineering, iut for helping us in different aspect. references [ ] the climate institute, “renewable energy: geothermal,” http://www.climate.org/ /topicsgreen/geo.shtml.(last visited march , .) [ ] debendra k. guha , herbert henkel, badrul imam “geothermal potential in bangladesh - results from investigations of abandoned deep wells” published in world geothermal congress bali, indonesia, page( - ) april . [ ] khandoker, r.a., and haque, m. “temperature distribution and its relation to hydrocarbon accumulation in sylhet trough, bangladesh”, bangladesh journal of geology, ( ). [ ] http://www.bgfcl.org.bd/daily_production% reports/dail y% prod% rep_opsx% . . .pdf [ ] bogmc, : petroleum exploration opportunities in bangladesh. bangladesh oil, gas and mineral corporation (petrobangla), dhaka. [ ] hossain, i., tsunogae, t., rajesh, h.m., chen, b., and arakawa, y., : ‘palaeoproterozoic u–pb shrimp zircon age from basement rocks in bangladesh: a possible remnant of columbia supercontinent. comptes rendus geosciences, , - . [ ] rahman, m., : geothermal potential resources in thakurgaon district, northern bangladesh. bangladesh j. geology, , - . h e p -p h - ba- - june , axion dissipation through the mixing of goldstone bosons k.s. babu, s.m. barr and d. seckel bartol research institute university of delaware, newark, de abstract by coupling axions strongly to a hidden sector, the energy density in coherent axions may be converted to radiative degrees of freedom, alleviating the \axion energy crisis". the strong coupling is achieved by mixing the axion and some other goldstone boson through their kinetic energy terms, in a manner reminiscent of paraphoton models. even with the strong coupling it proves di�cult to relax the axion energy density through particle absorption, due to the derivative na- ture of goldstone boson couplings and the e�ect of back reactions on the evolution of the axion number density. however, the distri- bution of other particle species in the hidden sector will be driven from equilibrium by the axion �eld oscillations. restoration of ther- mal equilibrium results in energy being transferred from the axions to massless particles, where it can redshift harmlessly without causing any cosmological problems. introduction goldstone and pseudo{goldstone bosons play a large role in the speculations of particle physicists and cosmologists. some oft{discussed examples are axions, majorons, familons, and the non{abelian goldstone �elds of texture models. the salient feature of the dynamics of goldstone bosons is that they couple derivatively. if the associated global continuous symmetryis broken at a scale f, then the coupling always involves powers of f� @�b, where b is the goldstone boson. the consequence of this is that if f is very large compared to the relevant masses and momenta, the goldstone boson decouples. this fact is exploited in invisible axion models, where for fa >� gev the axion's couplings are small enough for it to have evaded detection and avoided con
ict with astrophysical observations. this fact also lies behind the well{ known \axion energy problem", which is that if fa >� gev the energy in coherent oscillations of the axion �eld after the qcd phase transition in the early universe is unable to dissipate due to the axion's weak coupling and eventually overcloses the universe. in this letter we show that di�erent goldstone �elds can mix with each other through kinetic terms in the lagrangian in a way reminiscentof photon{ paraphoton mixing, and that a goldstone boson can thus acquire e�ective couplings at low energy to certain �elds which are much larger than the typical p=f. after demonstrating this point we show how it makes possi- ble scenarios in which the energy in coherent oscillations of the cosmological axion �eld can be dissipated and the upper limit on fa removed. mixing of goldstone bosons consider a theory with a global symmetry u( )a � u( )b. let and � be two scalar �elds with charges ( , ) and ( , ) under this symmetry. suppose that jh ij � fa and jh�ij � fb, where fb is assumed to be much smaller than fa, and call the resulting goldstone modes of and �, `a' and `b' respectively. then it is clear that couplings of a will be suppressed by p=fa and those of b by p=fb. it can happen that by integrating out some �elds of mass m an e�ective higher dimension operator will result of the u( )a � u( )b{invariant form lmix = c m y@� � y @ �� + h:c: ( ) if = (fa+~ )e ia=fa and � = (fb+~�)e ib=fb are substituted into this expression, the result contains the term la;b = �(@�a@�b) ( ) with � � � c fafb m : ( ) through this mixing of a and b, the `axion' a can couple to particles which have u( )b charges with e�ective strength �p=fb, which can be much greater than p=fa (see fig. ). for example, a term such as in eq. ( ) could arise from integrating out a �eld �, with charges (� = ;� = ), mass m, and coupling [�( �� ) + h:c:]. for simplicity let � have positive mass-squared and no vev. then the loop shown in fig. will produce the following e�ective term (among others) for momenta less than m: � � m ( y@� � y @ �� + h:c:) ( ) and therefore, from eq. ( ), � = � � � fafb m : ( ) now, given that the term �( �� ) exists, it would require an arti�cial can- cellation for m to be much less than �fafb, and hence for � to be much larger than �=( � ) � � . there is also an absolute limit that � < , since the kinetic terms of a and b have the form ( @�a @�b) � � � �� @�a @�b � and a wrong{sign metric would otherwise result. there is no reason, however, why � cannot be of order, though less than, unity. if the higher dimension term in eq. ( ) were a \hard" term all the way up to momenta of order fa, then the theory would become strongly coupled and physics uncalculable unless m were � f a and hence � were less than about fb=fa. the e�ective coupling of a to particles with u( )b charges through mixing then would be of order �p=fb � p=fa. in other words, the coupling of a would not be enhanced by this mixing. if, on the other hand, the term in eq. ( ) arises through a loop such as that shown in fig. where the intermediate particles have mass m � fafb, then it softens for momenta above m and no problem arises in higher order. alleviating the axion energy crisis we wish to make use of the mixing of goldstone bosons to let axions couple strongly to some other particles and thus, somehow, allow the primordial energy density in axions to be dissipated. let the �eld a be the axion that solves the strong cp problem. then u( )a has a qcd anomaly and a gets a mass of order � qcd=fa from instan- ton e�ects. several astrophysical arguments suggest that fa >� gev , otherwise the evolution of stars or their remnants would be drastically di�er- ent than observed. thus the coupling of the axion to ordinary matter, which is proportional to =fa, is highly suppressed. the axion energy crisis arises as a result of the small coupling and the small mass of the axion. at temperatures above the qcd phase transition the axion mass is small enough that _a � . as the universe cools, ma increases until the axion �eld becomes dynamic, i.e. ma > h, where h is the expansion rate. barring a coincidence of alignment for the peccei-quinn angle, the initial value of the axion �eld is a � fa. the axion number density is then na � f ah. after that point the number of axions in a comoving volume is constant, while the axion mass increases from h to its zero temperature value ma . if the energy density of axions after the qcd phase transition exceeds a critical value, �a;cr � � � qcd, then the the universe would become matter dominated too early, i.e. at temperatures >� ev . the energy density in axions at t � �qcd is roughly �a(�qcd) � � qcdfa=mpl, which results in the constraint fa < gev . in non-in
ationary models there are bound to be axionic strings - whose decay may or may not increase the axion abundance -fold, lowering the cosmological bound to fa <� gev . there have been several approaches to solving the axion energy crisis. for example, entropy production may dilute the energy density in axions relative to ordinary matter, or in
ation may �x the initial value of the peccei- quinn angle to a suitably small value . however, attempts to dissipate the axion energy typically fail. direct axion absorption presents several chal- lenges. first, the goldstone boson nature of axions demands a factor of =fa at each vertex. second, since the axions to be absorbed are non-relativistic the derivative couplings demand an additional factor of ma at each vertex. third, any process for single axion absorption must admit axion emission in the time reversed channel. this leads to a reduction in the dissipation rate by a factor of ma=t from a naive approach that would ignore the back reac- tions. flynn and randall considered the non-derivative coupling of axions to mesons , but the �rst and third arguments above were su�cient to leave axions undamped by several orders of magnitude. in the present case, the mixing of axions with some other goldstone boson allows the possibility of coupling axions strongly to some other non-standard matter. however, without some explicit symmetry breaking of the u( )b, the axions must couple derivatively. the combination of powers of ma from the couplings and from consideration of back reactions has caused all our attempts at axion absorption to fail. nonetheless, there is a mechanism whereby axion oscillations can be damped, allowing for fa of order the grand uni�ed scale mgut , or even the planck scale mpl. let the axion be mixed, as described above, with strength � with a goldstone boson b arising from the breaking of u( )b. the axion coupling to `b{matter', as we will call it, will be vastly stronger than its coupling to ordinary matter. our basic idea is then that the oscillating axion �eld causes the energies of b-particles to change in energy. if a thermal bath of such b-particles were present in the early universe when the axion �eld started to oscillate, then those oscillations would drive the b-distribution out of thermal equilibrium. by adjusting the interaction rates of the b-particles to a suitable value the axion energy can be dissipated into thermal energy of b particles. the �nal step is to note that the b goldstone boson is massless, so that all b energy can in principle redshift away as radiation. the axion energy is thus put into a harmless form which never dominates the universe. an explicit model to illustrate how this may happen let us calculate in a simple model in which the `b{matter' consists of the �eld � whose vacuum expectation value breaks u( )b and whose phase is b, and a scalar �eld � which has no vev. let the u( )b charges of � and � both be + and let them have a coupling ( g�� � + h:c:). the terms of the lagrangian that will be relevant for our analysis are l = (@�a) � m aa + (@�b) + �(@�a@ � b) + j@��j � m j�j � � � e� ib=fb� + h:c: � : ( ) the last term arises from expanding � as (fb + ~�)e ib=fb in the �� � coupling and de�ning � � gf b . at this point we are free to choose the parameters of l. for purposes of illustration it is convenient to choose fb � m � �qcd and to choose � somewhat less than m. these values are not absolutely necessary, but they clearly show the damping mechanism to work. the �rst task is to resolve the mixing of a and b. to bring the kinetic terms of a and b to canonical form we perform a non{orthogonal transformation a = a p � � b = b + �a : ( ) this gives l = (@�a ) � m a( � � )� a + (@�b ) + j@��j � m j�j � � e i=fb(�b + �a p �� ) � + h:c: ! : ( ) at this point it is convenient to drop the primes and work with the canon- ically normalized �elds. for further convenience we represent the coherent oscillation of the axion �eld by a(t) = a p � � sin(mat) : ( ) then the e�ective lagrangian for � in the presence of axion oscillations becomes leff = j@��j � m j�j � � � e i�(t)� + h:c: � ( ) with �(t) � (�a =fb)sin(mat). it is important to note that even though a(t) is slowly varying (with frequency ma), �(t) is rapidly varying: q � _�(t) = �a mafb cos(mat). since a ma = � = axion � � qcd(fa=mpl) = (initially), q � ��qcd. for time scales short compared to m� a we may treat q as being constant and write l as leff = j@��j � m j�j � � h e iqt� + h:c i : ( ) the problem now is to �nd the evolution of the � �eld, a non-trivial task because of the explicit time dependence. this is done in the appendix, but we give a simpli�ed version here. first, if � = then for each momentum ~k there would be two degenerate eigenstates. one could choose to work in a basis with linearly polarized or with circularly polarized states. with degenerate states it is easy to show that the hamiltonian is constant for any linear combination. next, consider the case � = , but q = . then the two eigenstates have masses (m � � ) = , and correspond to the linearly polarized states along the real and imaginary components of �; i.e. they are a(x�) and b(x�), where �(x�) = a(x�) + ib(x�). now, there is no explicit time dependence so the hamiltonian is still constant. this can be seen explicitly by writing the hamiltonian in terms of the linearly polarized states and observing that there is no mixing of di�erent frequency states in the hamiltonian. finally, for non{zero q, the hamiltonian is time dependent and the energy of the � �eld varies with time. for � small the evolution is well approximated by the � = eigenstates, but there is a qualitative di�erence between the linearly polarized and circularly polarized solutions. for the linearly polarized case, the potential in the a (or b) direction has a curvature that varies sinusoidally in time: m eff = m � � cos( qt). since we will assume q � m, the variation in m eff is adiabatic. in that case one expects each quantum to have energy q m + ~k + � cos( qt) ' ! + � ! cos( qt), where ! � q m + ~k . the number of quanta of oscillation is an adiabatic invariant. on the other hand, for the circularly polarized case, the state samples the potential at all phases of �. since m � q, this averaging takes place in a time small compared to the evolution of the potential and there is little time dependence in the energy. in the appendix we show that, in fact, the true eigenmodes are approximately circularly polarized. there is no time dependence for pure states; however, in a thermal bath we do not expect pure states unless there is some conserved quantum number. the corresponding symmetry in our case is the b symmetry, which is broken, so that b charge is not conserved. we therefore expect all polarizations to play a role, and having identi�ed the linearly polarized states as having an energy dependence driven by the axion �eld we look for dissipation of the axion energy through those modes. time variation of the energy levels of the � �eld can lead to dissipation. suppose the rate at which a linearly polarized � particle of momentum ~k scatters is given by 
(~k). then the occupation number f~k, of that state will obey the di�erential equation _f~k = 
( ~k) f @e(~k;t) t a � f~k(t) ( ) where e(~k;t) = ! + � ! cos( qt) and f is the equilibriumoccupation number (bose{einstein). treating �e t = � t! as small, this has solution f~k(t) = f � ! t � + f � ! t � 
p 
 + q � t! cos( qt + �) ( ) where f � @f =@x and tan� = �( q)=
. the occupation numbers thus `lag' by a phase � behind the equilibrium value as that oscillates in time. as 
 ! , this lag goes to zero and f~k(t) ! f � e(~k;t) t � ; the system remains in equilibrium. as 
 ! , the interactions turn o� and there is no time variation of f~k(t). maximum dissipation occurs for 
 = q. the average power dissipated over a period ( q)� by the mode with momentum~k is given by p = �( q) z ( q)� dt _f~k(t)e( ~k;t) = f � ! t � 
( q) q 
 + ( q) � ! t � z ( q)� dt sin( qt + �)cos( qt) ( ) or p = �f � ! t � 
( q) 
 + ( q) � ! t : ( ) the total power dissipated per unit volume is then given by p = � z d ~k ( �) f � ! t �" 
( q) 
 + ( q) # � ! t : ( ) the factor = comes from averaging over all possible polarizations of the � particles. equating the dissipation power with the change in axion energy density, p = _�a, and using hq i = d (�� = a =fbcos(mat)) e = � f b �a, the energy in coherent axion oscillations evolves as _�a ' � c(m;t) � �a
� 
 f b + � �a ; ( ) where c(m;t) = r dx x c +x f ( p c + x ), with c � m=t and x � k=t . let us now make the approximation that whatever dissipation occurs takes place in less than an expansion period - so that the functions 
 and c(m;t) may be approximated as constant. then, taking the integral r dt � : mpl=t , the �nal axion energy density is �a;fe � �a;f f b 
 = �a;ie � �a;i f b 
 e � � � � mpl f b 
t ( ) this solution embodies a number of special cases, but we are mostly in- terested in the cases where we can treat ( � �a)=(f b 
 ) as small. then, the axion density decreases exponentially during one expansion time. given that the maximum initial value of �a is approximately � qcd, as long as ( � � � mpl)=(f b 
t ) > , the axion density will be reduced to accept- able levels. we take the temperature to be about �qcd. dissipation is fastest if fb is small. on the other hand, if fb < t , the u( )b symmetry will be unbroken and the axion will have no goldstone boson, b, to mix with, and this dissipation mechanism will not operate. so the greatest dissipation should exist for fb � t � �qcd, and � � �qcd ! 
 �qcd !� � � : ( ) on the other hand, the dissipation cuts o� for q � � =m. so the energy in the axion �eld cannot be reduced below �f;min � � f b � m ( ) by this mechanism. demanding that this be less than � � � qcd in order to comfortably solve the axion energy problem gives (�=�qcd) � � � , and from eq. ( ), � (
=�qcd) � � � . these two constraints can easily be satis�ed, for example by � � � , 
 < � �qcd, and � � � � qcd. discussion we have established that it is possible to dissipate the primordial energy density in axions through their interactions with other particles. a key fea- ture of the process we envision is to mix the axion with some other goldstone boson b, whose decay constant fb is much smaller than fa. the mixing may be large, and this allow axions to couple strongly to `b matter'. by adjusting the matter content of the b-sector we can arrange for the axion oscillations to drive oscillations in the energy of b matter. this pushes the b matter out of thermal equilibrium, and ultimately allows the axion energy density to dissipate in the b-sector. although, we have constructed a model whereby the axions dissipate, the addition of new particles may have other troublesome consequences, chief of which is that b matter may itself come to dominate the universe. the easiest way to avoid this is to adjust the masses and couplings of the b-sector so the real part of the � �eld is the lightest b-particle other than the b goldstone boson itself. then as the universe cools, �rst all b matter will end up as �b's which will then decay with a rate of order fb into b goldstone bosons. we argued earlier that it is di�cult to dissipate axion energy through the process of single axion absorption, yet, in the present scenario axion energy is indeed absorbed. it is natural to ask if there is a \feynman diagram" explanation of our process. the answer is yes. imagine a process whereby a single axion is absorbed from the coherent state, as in fig. ( a) and a second process whereby two axions are absorbed, as in fig. ( b). the ratio of the rates for these two processes is r = � =� � na � m a f b ; ( ) where na is the occupation number for the state. as stated earlier the e�ec- tive single axion absorption rate is reduced by a factor of ma=t when back reactions are included. however, this is also true of the two axion absorption rate, and so the ratio in eq. ( ) is correct even in the presence of backre- actions. now, for the coherent state, na is approximated by na � f a=h , so the ratio becomes r � � m pl=� qcd, which is quite large. this leads to the situtation that two axion absorption formally exceeds one axion absorption. the three axion rate would be even larger... in this situation what one must do is sum over diagrams with any number of axions attached to the particles participating in the scattering process. this is equivalent to solving for the propagator of these particles in the presence of the coherent oscillating axion �eld, as we have done in this paper. along these lines, even in a normal axion model with no mixing each additional axion brings a factor of mpl=fa to the amplitude, so here also one should not calculate individual absorption rates. rather, one should calculate the propagators for the other particles, including the time dependent axion �eld, to arrive at the axion dissipation rate. we are presently considering the question of what dissipation may result from the non-derivative couplings to mesons, and plan to present results in a separate paper. although derivative couplings may seem important too, one must remember that such couplings are less e�ective at damping the non-relativistic coherent axion oscillations due to the factor of ma in the coupling. besides damping the coherent oscillations in the early universe, the kind of mixing of axions with other goldstone bosons we have been discussing could lead to other interesting e�ects. in particular, it is possible now to contemplate that even invisible axions with fa � mgut or mpl can have sizable couplings to some kinds of matter, perhaps even to particles that carry standard model gauge charges. this would mean that the \invisible axion" may not be quite as invisible as was thought. also worth further investigation is whether similar mixing in familiar majoron, familon or texture models could lead to interesting phenomena. appendix the easiest way to �nd the eigenstates of the lagrangian in eq. ( ) is to make the �eld rede�nition = eiqt�, after which the lagrangian becomes l = � j@� j � (m � q ) j j + iq( _ � � _ � � � ( + � ) � : (a ) the equations of motion for l are � � + (m � q ) � iq _ + � � = � � � � + (m � q ) � + iq _ � + � = : (a ) the solutions to these equations are i = �i � ei(!+t�k�x) + �+e �i(!+t�k�x) � or = �i � e�i(!�t�k�x) + ��e i(! � t�k�x) � ; (a ) where the index i denotes one of four solutions for a given wave vector ~k. due to the mixing of and �, to simultaneously solve both equations of motion requires that �i be either pure real or pure imaginary, but otherwise the normalization amplitude is arbitrary. the positive eigenfrequencies are given by !� � � ! + q � h ! q + � i = � = : (a ) negative frequency solutions for momentum ~k are equivalent to positive fre- quency solutions with momentum �~k, and so are not distinct. for the case when �i is real, the mixings are given by �� = �� ! � (!� � q) : (a ) for the case where �i is imaginary, the sign of � is changed. counting !�, and the real and imaginary �i, there are eight eigenfunc- tions combining the wavenumbers k and �k, which is the right number to determine the �eld and its �rst time derivative at each point; so this is a complete set of states for the �eld. for the � �eld, the states are given by �i = e �iqt i. we can choose any four of the eight eigenstates to characterize the momentumk (using the other four for �k). it seems natural to chose a set where ! � q ! ! as � ! , since in that limit we must get back the free �eld theory for �. with this in mind, the general solution that we will associate with momentum k is � = x s=� (�s+�s+ + i�s��s�) (a ) where the �ss are real numbers and where �ss � n � = ss h ( � �ss ) ei(!s�q)t�ik�x + �ss e�i(!s+q)t+ik�x i : (a ) here nss � ( � �ss ) + (�ss ) !s � s � ! + q + s h ! q + � i = � = �ss � ! + s � � (q � !s) q!s : (a ) for � < mq, which is the limit taken in the text, eqs. (a ) reduce to !s ' sm + q (a ) and �ss ' ss � q(m + sq) � � q (m + sq) : (a ) the energy density computed by just substituting eq. (a ) into the hamil- tonian density is � = � + re � � qe iqt � + ::: (a ) where the ellipses represent more rapidly varying terms (eg. terms varying with frequency !+ � !� or !s) and � = x s;s (�ss ) ! ; � q = � (�++ + i�+�)(��+ + i���) : (a ) the approximately `linearly polarized' modes with arg(�) ' �= correspond to (��+ + i���)=(�++ + i�+�) = e i�, whereas the approximately `circularly polarized' modes correspond to the cases (�++ + i�+�) = and (��+ + i���) = . for linearly polarized modes � / � ! + � cos( qt) � (a ) and the energy per quantum is e = ! + � ! cos( qt) (a ) as given in the text. references . r.d. peccei and h. quinn, phys. rev. lett. , ( ); s. weinberg, phys. rev. lett. , ( ); f. wilczek, phys. rev. lett. , ( ). . y. chikashige, r.n. mohapatra and r. peccei, phys. lett. b, ( ); g. gelmini and m. roncadelli, phys. lett. b, ( ); h. georgi, s. glashow, and s. nussinov, nucl. phys. b , ( ). . f. wilczek, phys. rev. lett. , ( ); d.b. reiss, phys. lett. b, ( ); g. gelmini, s. nussinov and t. yanagida, nucl. phys. b , ( ). . n. turok, phys. rev. lett. , ( ); n. turok and d. spergel, phys. rev. lett. , ( ). . j.e. kim, phys. rev. lett. , ( ); m.a. shifman, a.i. vainshtein and v.i. zakharov, nucl. phys. b , ( ); m. dine, w. fischler and m. srednicki, phys. lett. b, ( ); a.p. zhitniskii, sov. j. nucl phys. , ( ). . for reviews, see, j.e. kim, phys. rept. , ( ); m.s. turner, phys. rept. , ( ); g.g. ra�elt, phys. rept. , ( ). . j. preskill, m. wise and f. wilczek, phys. lett. b, ( ); l.f. abbott and p. sikivie, phys. lett. b, ( ); m. dine and w. fischler, phys. lett. b, ( ). . b. holdom, phys. lett. b, ( ). . r.l. davis, phys. rev. d , ( ); r.l. davis and e.p.s. shellard, nucl. phys. b , ( ). . d. harari and p. sikivie, phys. lett. b, ( ). . p. steinhardt and m.s. turner, phys. lett. b, ( ); g. lazarides, et al., nucl. phys. b , ( ). . s.-y. pi, phys. rev. d , ( ); a. linde, phys. lett. b, ( ). . j. flynn and l. randall, lbl preprint, lbl- ( ). . h. georgi, d. kaplan, and l. randall, phys. lett. b, ( ). figure captions figure . e�ective coupling to `b-matter' through goldstone boson mixing. figure . mixing of the � and scalars through a loop. the � particle carries both a and b charges. figure . similar processes involving the absorption of a) a single axion and b) two axions. if the axions come from the coherent state describing the classical �eld oscillation, then the rate for b) exceeds that for a). s cience scinc publisher: richard s. nicholson editor: daniel e. koshland, jr. deputy editor: ellis rubinstein managing editor: monica m. bradford deputy editors: philip h. abelson (engineering and appliedsciences;john . brauman (physical sciences); 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wendy k. shank, manager; catherine s. siskos, assistant manager; scherraine mack, associate; linda c. owens, macin- tosh operator art: amy decker henry, director; c. faber smith, associate director, diana defrancesco, technical il- lustrator; holly bishop, graphics assistant administrative support: leslie blizard a associate publisher: beth rosner circulation director: michael spinella see letters page for additional advertising and circulation staff charles j. arntzen elizabeth e. bailey david baltimore william f. brinkman e. margaret burbidge pierre-gilles de gennes joseph l. goldstein mary l. good harry b. gray john j. hopfield f. clark howell paul a. marks yasutomi nishizuka helen m. ranney robert m. solow edward c. stone james d. watson editorial president clinton's science adviser in the selection of his future science and technology adviser, president bill clinton chose quickly and well. jack gibbons was in the spotlight in little rock on december, along with major cabinet designees. gibbons brings to the president a unique mixture of knowledge and experience. the quality of his judgment and managerial skills in directing the office of technology assessment (ota) has won admiration on capitol hill and among observers elsewhere. in many instances ota assessments have been influential in the drafting of legislation. during gibbons's -year leadership at ota, more than assessments were issued. they dealt with such matters as renewable resources, energy, materials, agriculture, health, environment, computers, and education. the ota is an analytical support agency of the u.s. congress. governed by a - member bipartisan board (six senators and six representatives), ota works directly with and for congressional committees. the basic function of ota is to provide early indications of the probable beneficial and adverse impacts of technology. thus its director and staff are challenged to be future-oriented and aware of scientific developments that may affect society. the lengths of assessment reports vary; the median is approximately pages. they contain a rich body of factual material, some of it provided by experts at universities and elsewhere. in part because of the use of such temporary help, ota, with a staff of only about persons, has been able to produce drafts of reports in an unusually timely fashion. the drafts are subjected to numerous reviews by inside and outside experts to guarantee objective analyses. the reputation of ota owes much to gibbons's fostering of political nonparti- sanship and his refusal to allow the analytical quality of ota documents to be influenced by political expediency. for gibbons and the ota staff, the past years have been a stimulating set of learning experiences. in addition to good rapport with congress and a broad spectrum of knowledge gained during his years at ota, gibbons brings useful special expertise in areas that are likely to concern president clinton. no future u.s. president can escape dealing with nuclear-related issues or with the need to foster orderly evolution of the nation's supply and utilization of energy. before directing ota, gibbons was active in both nuclear and other energy matters. after receiving the ph.d. degree in at duke university, gibbons spent years in nuclear research at oak ridge national laboratory that included interdisciplinary work. his studies of mechanisms of nuclear synthesis of the heavy elements involved measuring nuclear cross sections for capture of neutrons having energies of the order of , electron volts. it was necessary to develop techniques for determining the velocity of neutrons traveling at million kilometers per hour over a flight path of as little as centimeters.* the techniques and results were important to nuclear theory and engineering. the results were relevant to understanding processes in stars and nuclear reactors. as early as the late s, gibbons began studies of u.s. energy efficiency and conser- vation. in , during the energy crisis of that year, he was named the first director of the u.s. office of energy conservation. the office began a major research and development program on energy efficiency leading toward a drop in the nation's energy consumption per unit of gross national product. going to knoxville in , he established the energy, environment, and resources center at the university of tennessee. from to , he served on many advisory committees and chaired the panel on conservation of the national academy of sciences-national research council committee on nuclear and alternative energy sys- tems. a paper based on a report of that panelt demonstrated a deep understanding of the problems and time constraints involved in modifying a nation's energy system. to maintain his usefulness with congress, gibbons wisely kept a low media profile. his style is nonconfrontational and quietly factual. he is a good listener. he possesses an enor- mous fund of stories and sayings, which he offers at the appropriate moment. he is capable of managing well in the new situation. if his knowledge and judgment are utilized appropri- ately, the nation, the president, and science will be well served. philip h. abelson *j. h. gibbons and r. l. macklin, science , ( ). tdemand and conservation panel of the com- mittee on nuclear and alternative energy systems, science , ( ). science * vol. * january science editorial board , o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ president clinton's science adviser philip h. abelson doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / references http://science.sciencemag.org/content/ / / #bibl this article cites articles, of which you can access for free permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the is a registered trademark of aaas.sciencescience, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for the advancement ofscience by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / http://science.sciencemag.org/content/ / / #bibl http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ international journal of recent technology and engineering (ijrte) international journal of recent technology and engineering (ijrte) issn: - , volume- issue- s , december published by: blue eyes intelligence engineering & sciences publication retrieval number: d s / ©beiesp doi: . /ijrte.d . s abstract: microgrids are handy units for a utility since their units such as distributed energy resources (der) and loads can able to control the power ingestion or production. moreover, it is used to assimilate renewable energy resources (res) to small distribution systems. battery energy storage systems (besss) are employed to recompense the sporadic output of res. similarly, dc microgrid for a home can be excellently controlled by an energy management system (ems) using fuzzy logic controller (flc) of -rules alone to control the power flow. the system has photovoltaic (pv), fuel cell (fc) and battery energy storage (bes). this study aims to introduce firefly algorithm (fa) to optimize flc in order to increase the system energy saving efficiency and to reduce the cost. keywords : bes, microgrid, ems, flc, fa i. introduction over dependence on fossil fuels would led to energy crisis. so, it is essential to identify eco-friendly and non- exhausted energy source and it is vital to initiate apt energy- saving methodologies to decelerate the energy consumption and to mitigate the environment impacts. energy monitor and control have more attention for research [ ], but a multi- function ems is still inattentive. hence, in this study, a cohesive ems with the tasks of energy monitor and control has been presented. previously, advanced metering infrastructure (ami) [ ], smart sensor [ ], smart home machines [ ], home area network (han) [ ] and home energy storage system (hess) [ ] have been introduced. smart home energy ems at a home can avoid redundant power consumption, enhance safety. energy conservation and emission minimization are the ultimate objectives of ems. revised manuscript received on december , . ms.nisha.v, electrical and electronics engineering, kalasalingam academy of research and education, anand nagar krishnankoil, virudhunagar, india, nisha.vaasudevan@gmail.com dr.v.vasudevan, information technology, kalasalingam academy of research and education, anand nagar, krishnannkoil, virudhunagar, india vasudevan_klu@yahoo.co.in dr.a.ramkumar,electrical and electronics engineering, kalasalingam academy of research and education, anand nagar, krishnannkoil, virudhunagar, india ramkumar.manonmani@gmail.com management (shem) deals with the utilization of supervisory control and data acquisition system (scada) with ems, comprising the generation, transmission and distribution systems under the idea of smart grid. shem is employed to visualize home res because of the emerging anxieties on energy safety and pollutant emissions. along with smart schemes shem can be installed at home and so as to improve efficiency [ ]. moreover, shem intends to perform demand side management (dsm) to deliver lenience to the utility and the consumers [ ]. this study aims to design and develop of a residential microgrid with flc. the system consists of pv, fc and bes. fuzzy rules have been augmented by fa to improve efficiency with the aim of energy conservation. fa attains the best values of scaling factors and membership functions of flc ii. mathematical model of the microgrid the modules of a microgrid have been illustrated in figure . the power electronic components buck/boost converters, mppt and inverters are assembled to build the microgrid system . fig. . structure diagram of a microgrid a. modeling of pv system the equivalent circuit of pv system has been shown in figure . it has a current source, a diode, series and shunt resistances. the intensity produced current of the solar cell is denoted as current, the nonlinear impedance is denoted by a diode, internal electrical losses are denoted by series resistance and shunt resistance represents the leakage current. when the intensity from sun falls on cell, dc power generated that differs gradually with the intensity of sun. modeling and simulation of a control algorithm for home energy management system nisha.v, v.vasudevan, a.ramkumar mailto:% % nisha.vaasudevan@gmail.com mailto:% vasudevan_klu@yahoo.co.in mailto:ramkumar.manonmani@gmail.com modeling and simulation of a control algorithm for home energy management system retrieval number: d s / ©beiesp doi: . /ijrte.d . s published by: blue eyes intelligence engineering & sciences publication fig. . equivalent circuit of pv system using kirchhoff's current law i  i ph  id  ish ( ) the photovoltaic current that alters with the intensity and temperature of sun have been provided as follow   sh s s s sph r irv aktn qirv iii           exp ( ) r sc rph i i ii  ( ) exp          t oc sc s av v i i ( ) exp           t s s d av irv i i ( ) sh s sh r irv i   ( ) q ktn v s t  ( )                 q idt soc t ( ) where i battery current q maximum capacity fig. . equivalent circuit of bes iii ems of the microgrid the power electronics components of microgrid have been modeled in matlab. the simulation diagram of proposed ems has been illustrated in figure . flc has been modeled with least fuzzy rules to minimize the intricacy. fig . simulink diagram of proposed ems a. description of the microgrid a kw of pv system has been interlinked with power electronic components namely dc/dc boost converter, mppt, etc. kwh capacity of li-ion bes has been utilized. the flc modeled for ems has been shown in figure . soc and the power difference have been set as the two input variables. fig . structure of flc modeled for ems ∆p signifies the power difference between produced power from pv power and load during hours. loadnewable ppp  re ( ) where prenewable solar power international journal of recent technology and engineering (ijrte) issn: - , volume- issue- s , december published by: blue eyes intelligence engineering & sciences publication retrieval number: d s / ©beiesp doi: . /ijrte.d . s pload power of the residential load flc tends to compensate the intermittency of res and to keep soc as least as possible. the operational range of bes is – % of its soc. table provides the fuzzy rules of flc. vl, l, m, h, vh signify very low, low, medium, high and very high respectively and the bn, sn, ze, sp, bp signify big negative, small negative, zero, small positive and big positive respectively. the optimization of flc has been performed to enhance the performance and energy saving. controlling bes according with altering loads with least number of fuzzy rules is a difficult task. hence, the optimization of flc need to be performed using intelligent technique. fa, a recent and successive optimization technique has been utilized. the steps involved in the implementation of fa has been directly adopted from [ ]. the error between present and actual power need to be minimized. soc fc power ∆p bn sn ze sp bp vl vh h l l vl l h m vl vl vl m vl vl vl vl vl h vl vl vl vl vl vh vl vl vl vl vl table i. fuzzy rules of flc   t dtef min ( ) where t execution time ∆e error between fc produced power and reference power fcf ppp  re ( ) where pfc fc power pref reference power otherwise ppppp p newableloadbesnewableload f rere re ,       ( ) where pbes is the power availed in bes. iv results and discussion the rated power generated by solar pv under idyllic weather; w/m of irradiation, and ◦ c of temperature. during the unavailability of solar pv and the lowest fc capacity level the bes tends to meet the demand. the load for the considered residence for a day has been illustrated in figure . the data of solar irradiation and temperature for producing power to meet the load has been shown in figure . the soc characteristics of bes has been exposed in figure . the details of energy investigations and the energy saving potentials of the proposed system have been presented in table . fig load of the residence for hours fig . data of solar irradiation and temperature for hours fig .soc characteristics of bes table ii. details of energy investigations and energy saving potentials factor energy load . kwh solar power . fuel cell (with normal flc) . fuel cell (with optimal flc) . without optimization . % with fa optimization . % v conclusion an enhanced flc-ems has been introduced for a microgrid involves solar pv, fc and bes to satisfy the demand of a home. a simple flc has been modeled only with fuzzy rules. the system has been modeled mathematically and optimized using fa to provide better results in control strategy and energy saving potential. modeling and simulation of a control algorithm for home energy management system retrieval number: d s / ©beiesp doi: . /ijrte.d . s published by: blue eyes intelligence engineering & sciences publication the simulations have been carried out in matlab. from the outcomes, it has been experienced that the energy saving potential has been enhanced by . %. the proposed approach can be easily implemented for any real-time system. references . g. song, f. ding, w. zhang, and a. song, "a wireless power outlet system for smart homes," ieee transactions on consumer electronics, vol. , no. , pp. - , . . a. ikpehai, b. adebisi, and m. k. rabie, "broadband plc for clustered advanced metering infrastructure (ami) architecture," energies, vol. , no. , . . a. m. ahmed, c. y. kang, and y.-c. kim, "communication network architectures for smart-house with renewable energy resources," energies, vol. , no. , . . z. bradac, v. kaczmarczyk, and p. fiedler, "optimal scheduling of domestic appliances via milp," energies, vol. , no. , . . m. collotta and g. pau, "a novel energy management approach for smart homes using bluetooth low energy," ieee journal on selected areas in communications, vol. , no. , pp. - , . . j. pascual, p. sanchis, and l. marroyo, "implementation and control of a residential electrothermal microgrid based on renewable energies, a hybrid storage system and demand side management," energies, vol. , no. , . . r. subbiah, a. pal, e. k. nordberg, a. marathe, and m. v. marathe, "energy demand model for residential sector: a first principles approach," ieee transactions on sustainable energy, vol. , no. , pp. - , . . n. javaid et al., "a hybrid genetic wind driven heuristic optimization algorithm for demand side management in smart grid," energies, vol. , no. , . . s. s. khan, h. shareef, a. wahyudie, and s. n. khalid, "novel dynamic semiempirical proton exchange membrane fuel cell model incorporating component voltages," international journal of energy research, vol. , no. , pp. - , / / . . k. c. udaiyakumar and m. chandrasekaran, "application of firefly algorithm in job shop scheduling problem for minimization of makespan," procedia engineering, vol. , pp. - , / / / . authors profile ms. v. nisha was born in chennai, tamil nadu, india. she received her ug degree in electrical and electronics engineering from sathyabama university, chennai and m.e. degree in power electronics and drives from anna university, chennai, tamil nadu, india, in . since september , she has been working as an assistant professor in the department of electrical & electronics engineering, kalasalingam university, krishnankoil, virudhunagar district, tamil nadu and india. she has attended several international conferences and he has been actively involving herself in research since . she has actively participated in various faculty development programs, symposiums, orientation programs, workshops and national seminars. dr.v. vasudevan received ph.d. degree in . he is currently serving as registrar and senior professor with the school of computing and information sciences, kalasalingam university, india. he has published papers in international journals and international conferences. his current research interests include distributed computing, grid computing, cloud computing and image processing. he has large volume of publications in refereed journals. he is a life time member of indian society of technical education (iste). dr. a. ramkumar received the ph.d degree from kalasalingam academy of research andeducation in the year of . he received the m.e (power systems) degree from faculty of engineering and technology, annamalai university, chidambaram, tamil nadu, india, in and received the b.e (electrical and electronics engineering) from thiagarajar collegeof engineering, m.k. university, madurai, tamil nadu, india in the year of . he hasbeen working as a associate professor in the department of electrical and electronicsengineering, kalasalingam academy of research and education, srivilliputhur, tamil nadu,since . he is having more than years’ experience in the field of teaching. his researchinterests include renewable energy, power system planning, power system analysis, highvoltage dc transmission systems, reactive power compensation, flexible actransmissions systems, electrical machines and power system automation. he is a lifemember of iste and member of ie(i). investigating the energy crisis in alzheimer disease using transcriptome study scientific reports | ( ) : | https://doi.org/ . /s - - -y www.nature.com/scientificreports investigating the energy crisis in alzheimer disease using transcriptome study s. akila parvathy dharshini , y.-h. taguchi & m. michael gromiha * alzheimer disease (ad) is a devastating neurological disorder, which initiates from hippocampus and proliferates to cortical regions. the neurons of hippocampus require higher energy to preserve the firing pattern. in ad, aberrant energy metabolism is the critical factor for neurodegeneration. however, the reason for the energy crisis in hippocampus neurons is still unresolved. transcriptome analysis enables us in understanding the underlying mechanism of energy crisis. in this study, we identified variants/ differential gene/transcript expression profiles from hippocampus rna-seq data. we predicted the effect of variants in transcription factor (tf) binding using in silico tools. further, a hippocampus-specific co-expression and functional interaction network were designed to decipher the relationships between tf and differentially expressed genes (dg). identified variants predominantly influence tf binding, which subsequently regulates the dg. from the results, we hypothesize that the loss of vascular integrity is the fundamental attribute for the energy crisis, which leads to neurodegeneration. alzheimer disease (ad) is one of the most common neurodegenerative disorders, which impacts more than million people globally with a steady increasing mortality rate . this disease is initiated in the hippocampus neu- rons located in the medial temporal lobe and spreads to the cortical regions of the brain . the selective vulnera- bility of the specific neuronal subset is a common factor for most neurodegenerative disorders and this selectively vulnerable neuron requires high energy to preserve the functional property, such as firing rate, ion homeostasis and synaptic transmission . therefore, disruption in energy metabolism leads to energy demand that eventually results in functional abnormality and cellular stress. metabolic stress is reported to be the dominant factor for selective vulnerability with a reduction in glyc- olytic and oxidative phosphorylation enzymes in ad , . based on genomic and transcriptomic studies, wang et al. , showed that hippocampus neurons are significantly susceptible to oxidative stress due to upregulation of reactive oxygen species (ros) and downregulation of antioxidant enzymes. this metabolic stress and ros affects the mitochondrial dna that further impairs mitochondrial morphology and stimulates the formation of inner mitochondrial transition pore (mtp), which leads to apoptosis and aberration in the electron transport chain enzymes, resulting in the defective metabolic process , . aberration in calcium dynamics disrupts the mito- chondrial morphology that induces energy demand . the gene expression studies illustrate that upregulation of n-methyl-d-aspartate receptors (nmda) promotes excitotoxicity and disrupts calcium dynamics and energy metabolism in hippocampus neuron . microarray data and large-scale co-expression network studies demonstrate an imbalance in the energy metabolism associated with neurodegeneration – . transcriptome-wide association studies of ad revealed that noncoding variants associated with ad-susceptible genes disrupt splicing and gene expression patterns which cause tau protein aggregation . even though the availability of experimental and computational studies mainly refer the defects in energy metabolism and protein degradation which leads to neurodegeneration – , the reason for the energy crisis in neurodegeneration has not yet been explored. it is also essential to identify the under- lying mechanism of the disease to determine a therapeutic strategy. analyzing high-throughput hippocampus rna-seq data may shed light to understand the disease mechanisms and provide profound insights into the cellular pathway, which helps in recognizing a potential drug target. rna-seq data plays an important role in identifying differential expressions, variants and fusion gene detec- tion. in this study, we retrieved hippocampus rna-seq data from sequence retrieval archive (sra) database . department of biotechnology, bhupat and jyoti mehta school of biosciences, indian institute of technology madras, chennai, , tamilnadu, india. department of physics, chuo university, kasuga, bunkyo-ku, tokyo, - , japan. *email: gromiha@iitm.ac.in open https://doi.org/ . /s - - -y http://orcid.org/ - - - mailto:gromiha@iitm.ac.in scientific reports | ( ) : | https://doi.org/ . /s - - -y www.nature.com/scientificreportswww.nature.com/scientificreports/ we identified variants from rna-seq data using genome analysis tool kit (gatk) and compared the predicted variants with expression quantitative trait loci (eqtl), genome-wide association study (gwas) for various neurological disorders – . gwas study reports the abundance of variants in the disease population, but it does not show the effect of variants. using in silico tools, we predicted the effect of variants on the transcription factor (tf) binding and epitranscriptomic modifications. thus, we have identified reported gwas variants and novel variants, where most of the identified variants disrupt tf binding. we performed differential expression analysis in three different levels: (i) gene expression (ii) transcript expression (iii) transcript proportions. we identified genes, which are differentially expressed at gene and transcript levels. to understand the relationship between predicted variants associate genes (vg), differentially expressed genes (dg) and tf, we built hippocampus-specific co-expression and functional module networks. from large-scale network studies, we found that most of the disrupted tfs are impacting the gene expression of differentially expressed genes. further, enrichment studies illustrate the dysregulation of novel dg is responsible for the blood vessel mor- phogenesis, blood circulation, gliogenesis, mitochondria biogenesis, ros response, lipid metabolism, endothelial and smooth muscle cells dysfunction. this study depicts the loss of vascular structural and functional integrity, which is the primary factor for the energy crisis in hippocampus neuron. we propose that restoring vascular dynamics and the blood-brain barrier (bbb) may save the surviving neuronal population against energy crisis. results variant calling-hippocampus rna-seq data. we have obtained the variants from stage of alzheimer patients using gatk tools by employing star spliced aligner and hg genomic assembly. we identified significant gwas and novel variants (supplementary table s , fig. s ). these variants are unique and not reported in any of the neurological disorders (termed as “novel”). among them, gwas variant associated genes (vg) and novel vg are differentially expressed (dg) in ad (supplementary table s ). effect of variants in methylation, histone acetylation and transcription factor binding. the variants located in conserved transcription binding sites or cis-regulatory elements can potentially interrupt tf binding. in addition, the epigenetic modifications such as methylation and histone acetylation play an essential role in controlling the gene expression profile . we evaluated the impact of variants in tf binding and epitran- scriptomic modifications and the number of variants altering gene expression, methylation, histone acetylation and tf binding are presented in supplementary table s . most of the variants ( ) interrupt tf binding and variants affect methylation and tf binding.the vari- ants identified in our studies are predominantly located in non-coding regulatory regions, and the disrupted tfs has been matched with the ad expression profiles from the literature study . supplementary table s represents the effect of gwas and novel variants. we analyzed the impact of epigenetic modification on non-coding vari- ants and the results are presented in table  . timm gene regulates the translocation of anti-oxidant enzymes and reduces the ros response. variants associated with this gene disrupt methylation, gene expression and as well, interrupt the binding of tfs (nanog, gli , tal , ccnt , tcf , yy , xzf, esr ). the upregulated tfs nanog and gli , involved in hedgehog signaling are essential for regeneration during tissue injury . the downregulated tfs such as tcf , tal , yy and zfx participate in neural and oligodendrocyte differentia- tion. esr helps to maintain hippocampal memory function by regulating apolipoprotein. psmc ip gene modulates the proteasomal activity and the variant, g/c (rs ) associated with this gene interrupts tf six , which is essential for retinal function and is involved in ad and amd. we identified a novel variant, c/t (rs ) in gene man b , which is involved in quality control and degradation process and it is downregulated in ad. man b also interrupts the tf involved in axon degradation signaling cascade (rreb ) and regulation of immune response (zbtb ) . category variant associated gene name differential gene expression study in ad chr position ref/alt genomic location snp id dysregulated regulatory elements in ad gwas/eqtl study methylation, gene expression and tf binding timm down a/g intronic rs nanog (up), tcf , tal (down) ad a/c utr rs esr , yy , zfx, ccnt (down) ad g/a intronic rs gli (up) ad ogfod down a/c utr rs jun (down) als rps down c/a intronic rs jun (down) ad psmc ip down g/c intronic rs six (down) ad, amd acp down c/t intronic rs irf (down), mef a (up) ad fam a up g/a intronic rs zbtb a (up) ad rps down c/g intronic rs nf (down) ad man b down c/t intronic rs rreb (down), zbtb (up) novel histone acetylation, gene expression and tf binding rbfox up g/a intronic rs rfx (down), dnmt (up) ad cdc down g/a intergenic rs nanog (up), tcf , mllt (down) ad hbs l up g/a intronic rs gfi b (down), hey (up) ad table . effect of predicted variants on epigenetic modifications and tf binding. https://doi.org/ . /s - - -y scientific reports | ( ) : | https://doi.org/ . /s - - -y www.nature.com/scientificreportswww.nature.com/scientificreports/ we have analyzed the number of tfs interrupted by variants and the number of variants influencing tf bind- ing, and the data are presented in fig.  . figure  a shows that the ftx gene (associated novel variants) disrupts the binding of different tfs (supplementary table s ). ftx belongs to the class of noncoding rna and it controls dna methylation and mirna regulation. variants in this gene may impact heterochromatin organi- zation . rbfox variants reported in ad disrupt the binding of tfs (supplementary table s ) and a few of them influence methylation and histone acetylation. further, this gene is upregulated in ad and involved in synaptic migration. the knockdown of this gene resulted in the aberrant structural integrity of the hippocampus neuron , . tmem variants reported in ad, als and amd also influence tfs. this gene is involved in cognitive function and regulates the axonal transport. figure  b represents the top tfs disrupted by large number of variants, such as nr c , rest and dnmt . nr c plays a significant role in stress response and is upregulated in ad . rest is essential for neuroprotection and neurogenesis and is downregulated in ad . dnmt is involved in epigenetic regulation that helps preserve methylation patterns and upregulated in ad. our gene expression studies also showed that nr c and dnmt are -fold upregulated (supplementary fig. s ).the variants present in ftx and rbfox disrupt the tfs binding of nr c , rest and dnmt . we have explored the variants affecting the tfs which are not reported in ad gene expression profile (termed as “novel tfs”) such as cux , dido and rora, which are found to be differentially expressed from our study (supplementary fig. s ). cux acts as a repressor of dendrite morphology regulation and inhibition of cux promotes dendritic arborization. dido gene participates in apoptosis. rora is involved in blood vessel mor- phogenesis, glucose metabolism, immune response, glutamate signaling, cholesterol metabolism and neuronal survival . in ad, we observed -fold upregulation of cux , dido and -fold upregulation of rora. differential gene/transcript expression analysis of hippocampus rna-seq. we computed dg obtained from transcriptome-based on salmon quantification method. supplementary fig. s represents the number of genes implicated in the differential expression, transcript and transcript usage. in this study, we clas- sified the differential expressed genes in three categories, which include ( ) changes in the transcript expres- sion (dte, differential transcript expression), ( ) changes in the gene expression (deg, differential expression gene) and ( ) changes in the transcript proportion between ad and control. the comparison of dg with existing gene expression profiles of ad showed that some genes are differentially expressed either in the gene, transcript and transcript proportions or combination of them (supplementary fig. s ). we compared the dg with various ad expression profile studies and identified some dgs are not reported in this profile (termed as “novel dg”). the differential expressed genes that influence gene/transcript expression and its proportions are presented in fig.  . figure  a illustrates the transcript proportions and expression of novel dg genes such as cmc , dvl and dnajc . cmc gene is widely expressed in brain tissue and plays a vital role in mitochondrial protein import . this gene is involved in the regulation of cytochrome c oxidation and downregulation of this gene may play a role in disrupting energy metabolism. dvl is implicated in wnt signaling and upregulation of this gene impacts the downstream signaling cascade. dnajc gene participates in mitochondrial biogenesis, protein transport inside and outside of mitochondria . upregulation of this gene may influence mitochondrial transport. figure  b represents the transcript proportions and their expression of known ad-associated genes such as optn, mum and ppp r c. optn gene participates in autophagy, vesicle transport, regulation of mitophagy and vasoconstriction (constriction of blood vessels, reducing blood flow) . however, upregulation of this gene may interfere with blood supply to neuron. ppp r c gene is involved in immune response, calcium signaling and regulates atp binding transporter activity. upregulation of this gene resulted in aberrant calcium signaling and immune response. this study illustrates the genes responsible for mitochondrial morphology, transport, energy metabolism, vasoconstriction and calcium regulation are impacted in ad. supplementary table s con- tains detailed information about the differential expression. figure . (a) the number of tfs affected by vg (b) the number of variants disrupting tfs. https://doi.org/ . /s - - -y scientific reports | ( ) : | https://doi.org/ . /s - - -y www.nature.com/scientificreportswww.nature.com/scientificreports/ the differential gene and transcript expression of few novel genes (flot , postn, dab ip, ccar , hla-dqa and hnrnpl) and known ad-associated genes (mdm , vps , tac , hdlbp, cct and camkk ) are shown in fig.  . novel genes. flot participates in vesicle-mediated transport, cholesterol metabolism and insulin signaling . downregulation of this gene may influence neurotransmitter transport and potassium channel activity. postn gene is associated with cell adhesion, regulation of blood circulation, axonogenesis and enhances neuroprotection . the downregulation of this gene may inhibit its neuroprotective role. dab ip gene acts as a negative regulator of vascular figure . differential transcript proportion and transcript expression for (a) novel and (b) known ad- associated genes (+upregulation, −downregulation, (+/− number in brackets refer to fold change)). https://doi.org/ . /s - - -y scientific reports | ( ) : | https://doi.org/ . /s - - -y www.nature.com/scientificreportswww.nature.com/scientificreports/ endothelial growth factor signaling and angiogenesis . further, it inhibits endothelial migration. upregulation of this gene may negatively regulate endothelial cell migration during tissue injury. ccar is involved in apoptosis, auto- phagy, and expressed in mitochondria. in the oxidative stress condition, this gene maintains mitochondrial integrity by inducing apoptosis . upregulation of this gene illustrates that this neuronal populationare subjected to tremendous oxidative stress, which in turn induces apoptotic signals. hla-dqa is associated with immune response and is abun- dantly present in microglia . overexpression of this gene may result in reactive microglia, which in turn produces neurotoxic cytokines that may cause neuronal death. this depicts that novel dgs are involved in microglial, oxidative stress, immune response, ion channel activity and endothelial functionality dysfunction. figure . differential gene and transcript expression for (a) novel and (b) known ad-associated genes (+upregulation, −downregulation, (+/− number in brackets refer to fold change)). https://doi.org/ . /s - - -y scientific reports | ( ) : | https://doi.org/ . /s - - -y www.nature.com/scientificreportswww.nature.com/scientificreports/ known ad-associated genes. mdm gene codes for ubiquitin ligase, which is involved in ubiquitin-mediated protein degradation, angiogenesis and the regulation of vascular endothelial growth factor . therefore, down- regulation of this gene may interrupt endothelial and blood vessel morphology. vps is involved in trafficking misfolded proteins for lysosomal degradation. this gene is downregulated in ad and shows impairment in the protein degradation process. tac gene acts as a potential vasodilator and may dilate blood vessels and increase the blood flow based on neuronal signals. downregulation of this gene may result in reduced blood supply to neuron.camkk participates in mitochondrial biogenesis and metabolic homeostasis. camkk excites ampa receptors and induces excitotoxicity. studies show that inhibiting camkk protects the hippocampus neurons from toxicity . upregulation of this gene may induce excitotoxicity through nmda receptor. functional enrichment studies of tf and differentially expressed genes. the functional enrich- ment analysis helps to identify the important biological function in the specified gene set. in this study, we per- formed enrichment studies of tf, differentially expressed genes as depicted in fig.  . figure  a represents the number of associated tf/dgs involved in biological functions. we observed that dysregulation of genes are asso- ciated with biological functions such as transport, metabolism, oxidative stress, lipid metabolism, ros response, mitochondrial function, gliogenesis, vascular endothelial pathways, smooth muscle cell regulation, blood vessel morphogenesis, immune response,apoptosis, autophagy and protein degradation. further, hippocampus-specific functional module analyses from humanbase revealed that dysregulation of genes are involved in angiogenesis, lipid transport, glucose transport, mitochondrial function and proteolysis (supplementary table s ). on the other hand, the identified tfs/dgs are involved in multiple biological functions (fig.  b). the tfs such as stat , bcl , rora (novel tf), jun, myc, srf and gata are involved in many biological functions. however, most of the tfs are downregulated in ad and these tfs are associated with immune response, home- ostasis, apoptosis, blood vessel morphogenesis and mitochondrial function. figure  c illustrates known-ad associated genes such as psen , pdcd ip, prkaca, sirt , apex, atf , optn, cd , fgf and mdm , linked in different biological functions. most of the genes are involved in figure . (a) functional enrichment study based on biological functions. the number of enriched biological functions corresponds to (b) tfs, (c) known ad-associated gene dg and (d) novel dg (tf-transcription factor, dg- differentially expressed genes). https://doi.org/ . /s - - -y scientific reports | ( ) : | https://doi.org/ . /s - - -y www.nature.com/scientificreportswww.nature.com/scientificreports/ immune response, apoptosis, lipid metabolism and blood vessel morphogenesis. figure  d depicts novel dg such as dab ip, zbtb c and sftap , which participate in multiple biological functions including apoptosis, immune response, defense response, lipid metabolism and vesicle transport. in summary, most of the dysreg- ulated genes in ad manipulates immune response, apoptosis, defense response, homeostasis and blood vessel morphogenesis. the detailed information about the functional enrichment analysis is depicted in supplementary table s . tissue-specific co-expression and functional interaction networks. we have built a hippocampus- specific co-expression network using differentially expressed genes, vgs, and tfs. from this network, we identified hub genes (degree > nodes) and the results are summarized in table  . nf is a tf involved in various biological functions and is abundantly expressed in oligodendrocytes, which insulate the neuron via myelin sheath. nf gene regulates the ras signaling pathway, which is essential for cellular growth and survival. downregulating this gene may disrupt neuronal survival. tsc is a novel dg and negatively regulates mtorc signaling, essential for lipid synthesis and inhibits autophagy. tsc is upregulated in ad and may inhibit mtorc functioning. ifnar is a novel dg involved in cell sur- vival akt signaling. downregulation of this gene may further impair neuronal survival. camkk gene plays an essential role in synapse formation and regulates downstream ampk signaling cascade. upregulation of this gene may disrupt the signaling pathways and induce excitotoxicity. grik and kcnma genes regulate the mem- brane potential using calcium signals. upregulation of these genes may impair the firing pattern of the neuron. we constructed the functional interaction network between the dgs, vgs, tf which assists in understanding how the tfs functionally associated to differentially expressed genes. the functional interaction details between the dg and tf genes including the hippocampus co-expression information are presented in fig.  . transcription factors. figure a showed that the ncor tf represses the novel tf, rora. we found that ncor downregulates and rora upregulates the gene expression in ad. these genes are co-expressed in the hippocampus and play an essential role in energy and lipid metabolism. ncor tf binding is influenced by novel (rs ) and known (rs ) variants in ftx and phc genes, respectively. rora tf binding is affected by stk (rs ) and slc f (rs ) variants. we also found that cux , a novel tf is acti- vated by rab b. cux and rar b are upregulated and co-expressed in the hippocampus, and are involved in the phagocytic activity and immune response. cux tf binding is interrupted by another ftx novel vari- ant (rs ) and a tmem (rs ) variant. further, we observed that, psmc (dg) activates nf (tf) and these genes are downregulated and co-expressed in the hippocampus. nf tf binding is disrupted by mettl (rs ), srebf (rs ) and snrnp (rs ) variants. also our study reveals that hbp (tf) which represses dnmt (tf) is downregulated in ad whereas dnmt is upregulated in ad. these genes are involved in chromatin remodeling . hbp tf binding is interrupted by slc a variant (rs ) and dnmt tf binding is affected by gwas variants and one novel znf (rs ) variant. novel dgs. figure b depicts jun (tf) activates the novel dgs postn and sftap . these genes are co-expressed in the hippocampus. jun tf binding is influenced by different variants. postn regulates the blood pressure and circulates through endothelial cells. sftap gene is involved in ros response and lipid metabolism. furthermore, the novel dg lepr is activated by tfs jun and tal which are affected by gwas variants. we found that, the novel dg ccar is activated by rest (tf) and it is affected by gwas variants and one ftx novel variant (rs ). ccar activates sirt , and sirt represses ccar . these genes are upregulated in ad and are implicated in apoptosis and ros response. in addition, we found that the novel dg sod is activated by tfs, foxa and nfkb , and these genes are co-expressed in the hippocampus. these tfs are affected by rbfox variants (rs , rs ). sod plays an important role in vascular integ- rity and mitochondrial function. we observed that nf (tf) activates the novel dg, dab ip and these genes are also co-expressed in hippocampus. dab ip and nf are involved in blood vessel morphogenesis, immune gene name type gene expression degree neighborhood connectivity closeness centrality biological function nf tf down . . apoptosis, immune response, blood vessel morphogenesis, gliogenesis, homeostasis, learning, neurogenesis, vascular endothelial pathway, chemical transmission tsc novel dg up . . akt/wnt signaling, autophagy, apoptosis, vesicle transport, mitochondrial regulation ifnar novel dg down . . akt signaling, immune response ddx b novel dg up . . regulation of vascular smooth muscle cells dvl novel dg up . . neurogenesis, wnt signaling camkk reported dg up . . autophagy, mitochondrial biogenesis, ros response tcf reported dg up . . immune response kcnma variant up . . homeostasis, membrane potential grik variant up . . apoptosis, defense response, energy metabolism, exocytosis, membrane potential table . hub genes identified from hippocampus specific co-expression network. https://doi.org/ . /s - - -y scientific reports | ( ) : | https://doi.org/ . /s - - -y www.nature.com/scientificreportswww.nature.com/scientificreports/ response, gliogenesis and apoptosis. in addition, the novel dg ifnar and stat (tf) activate each other and are downregulated in ad. stat tf binding is interrupted by amacr (rs ) variant. these genes participate in defense response. known ad associated dgs. tfs nfkb , bcl a, activates optn (dg) and these genes are co-expressed in hippocampus and are involved in neurogenesis and defense response. nfkb and bcl a tfs binding is interrupted by gwas variants (figure c). we observed that the camkk (dg) is activated by e f (tf) and lepr (dg) and co-expressed in hippocampus. e f tf binding is disrupted by mkx(rs ), znf (rs ) and elav (rs ). furthermore, we identified that tac (dg) is repressed by rest (tf) and is involved in lipid metabolism. based on this analysis, the predicted differentially expressed genes are con- nected with tfs either by functional interaction or by co-expression. however, changes in tf binding or expres- sion may affect the target gene regulation and biological function. hypothesis for the energy crisis in hippocampus neuron. the hippocampus neuron needs relatively more energy than other neurons to maintain its structural and functional integrity. these neurons exhibit an increased ros (reactive oxygen species) response to oxidative stress and have higher energy demands . in nor- mal condition (supplementary fig. s ) the mechanism involves the following steps: (i) the bbb (blood brain bar- rier) helps to preserve vascular structure by maintaining endothelial cell functional integrity. this saves the brain from toxic substances (ii) the microglia plays a crucial role in the immune response and releases neurotrophic factors that can improve neuronal survival (iii) the vascular smooth muscles regulate the blood pressure based on the neuronal demand, which is communicated through glial cells (iv) the glial cells communicate with neuron as well as vascular smooth muscles and act as a key regulator that controls the cerebral blood flow based on the figure . the functional interactions between important differentially expressed genes and tfs. https://doi.org/ . /s - - -y scientific reports | ( ) : | https://doi.org/ . /s - - -y www.nature.com/scientificreportswww.nature.com/scientificreports/ neuronal activity by regulating vasodilators and vasoconstrictors (v) after an actionpotential, the increased amount of potassium ions (k+) in the extracellular region is taken up by glia (astrocytes) through gap junction and acts as a potential vasodilator, dilating the blood vessels and increasing blood supply. based on glutamate and k+ concentration, glial cells sense neuronal activity and regulate calcium dynamics, which in turn regulates the vasodilator and constrictor (vi) further, insulin receptors regulate glucose transporters (glut) which in turn help to increase the concentration of intracellular glucose (vii) in the glial cells, glucose is converted to lactate through glycolysis. lactate is transported to the neurons, where it undergoes oxidative phosphorylation. (viii) the neurons mainly depend on oxidative phosphorylation for meeting their energy needs. the neurons utilize this energy to maintain their functional integrity (protein degradation, ion homeostasis, vesicle transport and firing pattern). hence, the energy supply improves neuronal survival , . based on the current study and available literature, we have outlined the reason for the energy crisis in the hippocampus in fig.  . ( ) in the disease condition, leaky endothelial cells may allow the transport of toxic invaders into the neuron, thus interrupting the vascular dynamics and cerebral blood flow . ( ) if tissue injury occurs, the microglia will release neurotoxic substances and inflammatory cytokines, which indirectly affect the vascular structure. ( ) aberrations in smooth muscle cells and imbalance in the vasoregulatory substances affect blood pressure and reduce cerebral blood flow. ( ) the insulin resistance influences glut and leads to lower intracellular glucose concentration. ( ) disruption in vascular and glial functionality leads to reduced cerebral blood flow, which in turn reduces insulin and glucose metabolism and leads to a deficiency in the lactate supply to the neurons. ( ) the reduced supply of lactate and glucose results in diminished oxidative phosphorylation. ( ) aberration in glutamate uptake leads to higher concentration of glutamate in the synapse which upregu- lates nmda/ampa receptor and induces excitotoxicity. ( ) this type of excitotoxicity allows increased calcium flux in the er (endoplasmic reticulum), which in turn increases calcium influx in the mitochondria, leading to mtp formation, swelling and apoptosis. ( ) disruption in mitochondrial morphology and diminished oxidative phosphorylation leads to enormous energy demands in the neurons, resulting in an energy crisis. ( ) in order to maintain the firing pattern and ion homeostasis, neurons require higher energy. this type of energy demand may disturb the firing pattern in the neuron. along with this energy crisis, additional cytotoxic agents (such as protein aggregates) and calcium load further increase the energy demand and subsequently, neuronal vulnerability is higher compared to other neurons. in the current study, we have deciphered the dysregulation of the novel and reported expressed genes involved in the functional aspects and are listed in supplementary table s . from this, we propose that aberration in vascular structural integrity, gliogenesis are the primary factors responsible for high energy demands, resulting in dysfunctional glucose metabolism, energy imbalance and neuronal vulnerability. this study shows that pre- serving the vascular integrity and bbb homeostasis may help to shield the hippocampus neuron from the energy crisis and associated energy-related functions. fluctuation in the cerebral blood flow may be a nearly indicator for energy crisis and cell loss. discussion the variant analysis for stage of ad showed that the predicted variants are influencing tf binding and epi- transcriptomic modifications. the comparison of these variants with gwas and eqtl studies of ad and other neurological disorders revealed the mechanism behind the energy crisis of ad. the ftx novel variants disrupt different tfs, which are involved in crucial biological functions,including blood vessel morphogenesis, apoptosis, immune response and neurogenesis. from the literature, we noticed that these tfs are differentially expressed in ad. the tfs identified in our study agree with experimentally known observations , . further, tfs nr c , dnmt impacted by the higher number of variants and are differentially expressed. man b associated novel variant (rs ) disrupts methylation, gene expression and tf binding. the predicted gwas variants inter- rupt the binding of novel tfs such as rora, cux and irf . we identified dysregulation of this novel tfs in our differential expression study. from our differential expression study we have captured literature reported genes, novel differentially expressed genes with isoform resolution. among them, genes were observed with the changes in both tran- script expression and transcript proportions. in some of the cases, we observed the changes in the transcript pro- portion level, but there is no change in the gene expression level. this may be due to differential transcript usage. functional enrichment analysis revealed that novel differentially expressed genes are related to blood vessel morphogenesis (dab ip, lepr, sod , sema a, rora), blood pressure regulation (cacna c, cacna d, postn, sod , zbtb c), vascular endothelial pathways (dab ip, pik r , map k ), vascular smooth cell regulation (sod , zbtb c), and gliogenesis (rora, dab ip, fpr ), insulin secretion (cacna c, capn ), mitochondria biogenesis and regulation (minos , sod , ccar , dnajc , lepr, timmdc ), ros response (cyp e , eif a, prkra, sftpa , sod , zbtb c), lipid metabolism (rora, dab ip, pik r , sftpa , slc a , zbtb c, ntsr ) and energy metabolism (ntsr , rora, zbtb c, men , lepr) are dysregulated in ad. tissue-specific co-expression network between tf, dg and vg showed that dvl , nf , kcnma , ifnar and grik genes are highly connected with other genes and act as potential hubs. from the functional interac- tion network, we identified differentially expressed genes regulated by tfs and showed there is an intrinsic func- tional relationship between them. e.g., novel dg’s (sod , postn, rora, sftap and lepr) are involved in energy metabolism and vascular function. sod gene regulated by nfkb and foxa tfs. these tfs binding https://doi.org/ . /s - - -y scientific reports | ( ) : | https://doi.org/ . /s - - -y www.nature.com/scientificreportswww.nature.com/scientificreports/ are influenced by rbfox variant. novel tf rora influenced by ncor tf and novel variant ftx disrupts the binding of ncor . postn and sftap activated by jun tf and this tf binding affected by kcnma variant. lepr activated by jun and tal , both of these tfs are influenced by rbfox variant. in summary, we identified the variants from rna-seq data that may affect the binding of tf. from the functional network, we deciphered the relationship between the predicted tfs and dg. hence, this study decodes how the variants may disrupt the tf binding which in turn dysregulates the downstream gene expression. the gene expression and network study from hippocampus neuron provide deep insights to understand the underlying mechanism for the energy crisis in the specific neuronal populations. from this study, we propose that restoration of the bbb, vascular integrity and glial function may rescue the surviving hippocampus neuron from the energy crisis and cell death. examining the cerebral blood flow in control and disease samples may provide additional information to energy crisis before damaging the energy demanding neuron. extending this study to single cell rna level may shed further light on the energy crisis in neurodegenerative disorders. conclusion the hippocampus neurons need huge energy for its functionality and these neurons are selectively vulnerable in ad pathogenesis. however, the underlying cause for metabolic stress is still unknown. in this study, we per- formed variant and differential expression profile analysis from hippocampus rna-seq data. the variant analysis showed that most of the gwas and novel variants disrupt the tf binding. we identified differentially expressed genes with transcript level resolution. the functional interaction network depicts that there is an intrinsic rela- tionship between tf and differentially expressed genes. the large scale network and functional enrichment figure . proposed mechanism for the energy crisis in hippocampus neuron in ad. https://doi.org/ . /s - - -y scientific reports | ( ) : | https://doi.org/ . /s - - -y www.nature.com/scientificreportswww.nature.com/scientificreports/ studies reveals that during hypoxic condition, these neurons release the inflammatory cytokines, which can be assessed by astrocytes and microglia. the increased cytokine and ros response may affect the structural integ- rity of endothelial and vascular smooth muscle cells, which eventually increase the permeability of the bbb that allows toxic invaders inside the brain. these events further enhance the inflammatory response and it impairs the cerebral blood pressure that leads to reduction of regional cerebral blood flow. the communication loss between glia and vasculature influences insulin resistance that additionally induces inflammation and reduces the glucose uptake that leads to glucose hypo metabolism. however, the reduced levels of glucose influence the lactate shuttle, which in turn resulted in diminished oxidative phosphorylation. all these above events impose a greater meta- bolic stress on this neural population. along with this energy crisis, an additional stress such as protein aggrega- tion, genetic risk factors and calcium load expands the vulnerability of this neuron in a higher rate compared to others. this shows imbalance between energy supply and demand, which drastically hampers the energy craving neuron and leads to selective neurodegeneration. this study suggests that constant monitoring and restoration of vasculature may secure these neurons before the energy crisis. methods variant analysis. the rna-seq samples were retrieved from the sra database and reads were preproc- essed to remove the adapter, hexamer contamination, and low phred quality reads (q < ) using trim galore . the preprocessed fastq files are subjected to spliced alignment with known hg genomic annotation using star . . details on samples and processed reads are tabulated in supplementary table s . the duplicates from the aligned files were discarded using picard tools and the aligned files were subjected to variant calling using the gatk . for evaluating the variants, we used stringent filtering criteria such as minimum read depth > , phred score > , ts/tv > . and padj value < . in order to avoid false positive variant call . we compared the predicted variants with gwas and eqtl studies from various neurological disorders listed in supplementary table s . the vgs are compared with differential expression profiles of alzheimer disease, which are obtained from various literature sources, gene expression omnibus (geo) and the humanmine database . this comparison also assists in confirming the variants already reported in gwas and any novel variants identified from the current analysis. gwas provide information on the variants predominantly present in the disease population but not on the effect of variants. in this work, we predict the effects of variants in transcription binding and epi-transcriptomic modifications using haploreg , snp tfbs , gwas d and rmbase data- bases as well as gene expression using deep learning networks and xqtl analysis – . the xqtl study comprises control samples from frontal cortex area procured from old aged people, which provides the effect of variants in methylation, histone acetylation and gene expression. differential gene/transcript expression and differential transcript usage analysis. the preproc- essed rna-seq sample reads are subjected to alignment-free transcriptome based lightweight mapping using salmon . this procedure maps the preprocessed reads with ensembl mrna hg transcriptome sequences and counts the overlapping reads with the given transcripts. we imported the transcript abundance using tximport in order to identify gene-level expression. we used negative binomial generalized linear and dispersion model from deseq to identify the differentially expressed genes. we analyzed the variance within and between the biological replicates. using statistical parameters (false discovery rate < . , minimum fold change |log fc| > ) we filtered the differential expression genes/transcripts. further, using salmon count data, we performed differen- tial transcript usage using drimseq and stager which helps to identify the transcript proportions between two different conditions. this study aids in understanding the differential expression profiles of the gene, transcript and transcript proportions. the overall workflow for variant and differential expression analysis is depicted in supplementary fig. s . network and enrichment analysis. the large-scale network analysis helps to decipher the functional interaction between the given gene set. the functional enrichment, pathway analysis of tfs, dgs and predicted vgs are carried out by intermine, kegg, reactome and cluego cytoscape app , . we have built hippocam- pus specific co-expression network, which is obtained from predicted tf, dg and vg using humanbase . this assists in identifying the potential gene hubs based on various network measures. we constructed a functional interaction network for identifying interactions between dg, vg and tf using reactomefi cytoscape app and trrust v database , . trrust provides regulatory information that includes tf target genes and their functional association. this type of study helps in understanding the interaction between tf and dg. received: april ; accepted: november ; published: xx xx xxxx references . martin prince, a. et al. world alzheimer report the global impact of dementia an analysis of prevalence, incidence, cost and trends. 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- -y. correspondence and requests for materials should be addressed to m.m.g. reprints and permissions information is available at www.nature.com/reprints. publisher’s note springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. open access this article is licensed under a creative commons attribution . international license, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the cre- ative commons license, and indicate if changes were made. the images or other third party material in this article are included in the article’s creative commons license, unless indicated otherwise in a credit line to the material. if material is not included in the article’s creative commons license and your intended use is not per- mitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. to view a copy of this license, visit http://creativecommons.org/licenses/by/ . /. © the author(s) https://doi.org/ . /s - - -y https://doi.org/ . /s - - -y http://www.nature.com/reprints http://creativecommons.org/licenses/by/ . / 	investigating the energy crisis in alzheimer disease using transcriptome study
 	results
 	variant calling-hippocampus rna-seq data. 	effect of variants in methylation, histone acetylation and transcription factor binding. 	differential gene/transcript expression analysis of hippocampus rna-seq. 	novel genes. 	known ad-associated genes. 	functional enrichment studies of tf and differentially expressed genes. 	tissue-specific co-expression and functional interaction networks. 	transcription factors. 	novel dgs. 	known ad associated dgs. 	hypothesis for the energy crisis in hippocampus neuron. 	discussion
 	conclusion
 	methods
 	variant analysis. 	differential gene/transcript expression and differential transcript usage analysis. 	network and enrichment analysis. 	acknowledgements
 	figure (a) the number of tfs affected by vg (b) the number of variants disrupting tfs. 	figure differential transcript proportion and transcript expression for (a) novel and (b) known ad-associated genes (+upregulation, −downregulation, (+/− number in brackets refer to fold change)). 	figure differential gene and transcript expression for (a) novel and (b) known ad-associated genes (+upregulation, −downregulation, (+/− number in brackets refer to fold change)). 	figure (a) functional enrichment study based on biological functions. 	figure the functional interactions between important differentially expressed genes and tfs. 	figure proposed mechanism for the energy crisis in hippocampus neuron in ad. 	table effect of predicted variants on epigenetic modifications and tf binding. 	table hub genes identified from hippocampus specific co-expression network. ��social capitalism�� in renewable energy generation: china and california comparisons aalborg universitet "social capitalism" in renewable energy generation: china and california comparisons clark, woodrow w; li, xing published in: utilities policy doi (link to publication from publisher): . /j.jup. . . publication date: document version early version, also known as pre-print link to publication from aalborg university citation for published version (apa): clark, w. w., & li, x. ( ). "social capitalism" in renewable energy generation: china and california comparisons. utilities policy, ( ), - . https://doi.org/ . /j.jup. . . general rights copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. ? users may download and print one copy of any publication from the public portal for the purpose of private study or research. ? you may not further distribute the material or use it for any profit-making activity or commercial gain ? you may freely distribute the url identifying the publication in the public portal ? take down policy if you believe that this document breaches copyright please contact us at vbn@aub.aau.dk providing details, and we will remove access to the work immediately and investigate your claim. downloaded from vbn.aau.dk on: april , https://doi.org/ . /j.jup. . . https://vbn.aau.dk/en/publications/ d a -d c- de-bb - ea e b https://doi.org/ . /j.jup. . . lable at sciencedirect utilities policy ( ) – contents lists avai utilities policy j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / j u p ‘‘social capitalism’’ in renewable energy generation: china and california comparisonsq woodrow w. clark ii , xing li*, clark strategic partners, po box , beverly hills, ca , united states. a r t i c l e i n f o article history: received august received in revised form november accepted may keywords: economics energy infrastructures renewable energy social capitalism q clark gave this paper given at the western econo annual meeting in san diego, ca in july about one imar. basic concepts apply now and for the fut comparisons and perspectives are needed for the eu significance of energy and the global economic crises * corresponding author. e-mail address: wwclark @gmail.com (w.w. clar dr. clark was the senior foreign energy advisor mous region, prc. he is a qualitative economist who strategic partners in los angeles, ca. his most communities due in oct from springer press. professor li xing teaches development policy and denmark. his work in china has resulted in a china and most recent publication is, globalization & tran opportunities and alternatives. - /$ – see front matter � published by doi: . /j.jup. . . a b s t r a c t with a population of over . billion people, demand for renewable energy is expected to grow to a usd $ billion market in the near term. under renewable energy law (rel) in february in the people’s republic of china (prc) passed by the national congress, renewable energy projects will be able to receive a range of financial incentives starting in , which will more than double the prc current renewable energy generation from % to % by . most of the increase will be in hydroelectric generated power. nonetheless, the nation and especially the provinces are moving rapidly to develop a wide range of renewable energy generation including solar, wind, geothermal and run of the river. because china practices ‘‘social capitalism’’ as expressed in it’s recurrent five year national plans since , the national government and all the provinces have programs, unlike many western and indus- trialized nations, to ‘‘plan’’ and provide for infrastructures. this paper concerns only the energy infra- structure sector and renewable energy generation in particular. the planning process includes financial incentives and investments which are a major part of the chinese law focused on ‘‘encouraging foreign investment industries’’. the key part of the law is to guarantee long-term power purchase agreements with state owned and controlled ‘‘utilities’’. in short, china may have gotten the economics of the energy sector correct in its concern for planning and finance. the paper develops these energy infrastructure ideas along with the legal and financial requirements as ‘‘lessons’’ learned from the usa and especially california. these lessons now apply to china and allow it to learn from the american mistakes. empirical data will be drawn from work done in china that examine the renewable energy generation and infrastructures and hence allow the rpc and its provinces to ‘‘leap frog ’’the mistakes of other developed nations. further lessons will be learned from provinces and related infrastructures in china, such as water, transportation, environment, waste and telecom- munications. more significantly, the usa and western industrialized nations may now learn from the chinese. � published by elsevier ltd. mic international association year into the abd project on ure of the imar and prc. , japan and usa due to the continuing in . k ii). for inner mongolia autono- is managing director of clark recent book is sustainable theory at aalborg university, center at aalborg university snational capitalism: crises, elsevier ltd. . background china has established itself as ‘‘social capitalist’’ nation over the last decade as it moves away from a strict communist nation into one that combines western capitalism with socialist principles (clark and li, ). meanwhile meeting the challenges of an economic annual growth rate reported at % annually for two decades, the nation confronts serious structural reform. energy is a significant and core sector. the prc has the second largest elec- tricity supply system in the world. since implementation of reform and opening-up policy in the early and mid- s, the power industry has grown over % per year in terms of installation capacity and generation. the country has gw in installed capacity (at the end of ) and a total length of , km of above kv transmission lines (at the end of ). the hydro, the mailto:wwclark @gmail.com www.sciencedirect.com/science/journal/ http://www.elsevier.com/locate/jup coal-based thermal generating capacity in will reach – gw. natural gas generating capacity will rise up to – gw. the size of nuclear capacity and other sources of energy are expected to increase as well during this period. in china, energy resources for electric generation are mainly scattered in the west, while electricity consumption is concentrated in the center, east, and south. so china needs transmitting power from west to east, exchanging power between south and north, and enhancing nationwide interconnection. as coal is expected to play an important role, promotion of clean coal technologies (including high effi- cient decoking and dust eliminating equipment and sealed equipment for coal transmission) for new power plants is essential from environmental perspectives. large-scale power construction and hydroelectric construction without damaging the local environment is also an area of concern (han et al., , see appendix a). w.w. clark ii, x. li / utilities policy ( ) – thermal, and the nuclear power capacity amounted to . gw ( %), . gw ( %), and . gw ( %) respectively (han et al., ). ‘‘china faces a challenge similar to that it did two decades ago – it aims to quadruple gdp before while only doubling energy use to meet energy security, social welfare, and environ- mental imperatives’’ (sinton et al., ). the prc’s electricity generation in amounted to . twh and electricity consumption was . twh. industry is the largest consumer of electricity with a share of %. the shares of agriculture, resi- dential, and other consumers are estimated at . %, . % and . % respectively. currently, china’s electric power industry has entered a new development phase with large grid, large genera- tion plants, high-voltage transmission, and advanced automatic control systems (han et al., , see appendix a). ‘‘in order to solve the energy problem, chinese government works out two solutions. one is to promote the energy conserva- tion, speed up the construction of a thrifty type economic system and society, largely improve the efficiency of energy utilization, lead the social production and consumption to a sustainable pattern, thus to bridge the gap of the energy resource. the other is to enhance the exploration and development of domestic energy resource, accelerate the generation of coal, electricity, oil, natural gas, as well as the construction of renewable energy strive to adjust and optimize the energy structure. at the same time, china should proactively participate international energy development and collaboration, take advantage of foreign energy resource as to ensure the civil energy supply.’’ (han et al., , see appendix a). under social capitalism, the prc seeks to open up targeted sectors, like energy, to private capital, foreign investment and entrepreneurial economic development. however, lessons from developed nations are important. in denmark and other nordic countries who have similar social-economic overall policies about ‘‘social capitalism’’ like the prc. for example, in order for private and public sectors to collaborate successfully in what clark and lund ( ) call ‘‘civic-markets’’, the central government must set up finance programs that have certain requirements. the key was that the government remains at least a controlling equity partner in the newly established venture for an established period to time (clark and jensen, ). the same concept applies well to devel- oping nations and new members to the european union, such as hungary who were ‘‘privatizing’’ their energy sector in the mid and late s with ‘‘difficult results’’ (clark, a,b). in the case of california’s ‘‘de-regulated’’ (similar to privatization and liberalization elsewhere) energy sector that took effect in , publicly controlled power plants were % sold to private companies outright from to resulting in disastrous consequences including state-wide rolling black outs, state government budget deficits and the state going bankrupt. none- theless, there were both good results or new opportunities found (clark and bradshaw, ) and bad lessons learned (clark and demirag, ; clark, , a,b) and that have helped change public policies in california and america in general. reform is top on the prc agenda as well. sinton et al. ( ) among others have analyzed the energy sector and made recom- mendations. in china, the national transmission lines belong to two state-owned grid companies founded in december in compli- ance with the state council’s power system reform strategy and program. the country’s power generation capacity belongs to five state-owned power generation group companies founded in december and other generation companies. despite significant growth in installed capacity and generation, the country continued to face shortages of electricity supply in (han et al. ). consequently, some provinces, autonomous regions, and municipalities had to cut off electricity at peak times. in order to guarantee more power supply, china is accelerating construction of new electricity plants and power grids. one of the core issues is, are these new plants environmentally friendly? that is will they help or hinter environmental protection for the regions and cities that are demanding more energy generation, but hopefully not at a long-term atmospheric cost. at the same time, the government has adopted a series of incentive and punitive measures encouraging balanced electricity consumption. according to the forecast of the china electricity industry asso- ciation, china’s power generation capacity will grow by % in , while the consumption of electricity will increase by % (xinhua news, ). china’s electricity consumption per capita is very low compared to most other developed nations. however, the forecasted demand increase for electricity will be huge in the future. according to the forecasts of energy research institute, the demand for electricity will increase with annual growth rate over % in the next years and could be even about %. based on that, national demand, china would need energy generation between and twh in and between and twh by (han et al., ). to meet this demand, the required installed capacity is from to gw in . the eri study suggests that the hydro elec- tricity capacity has to be increased to gw in from the present size of . gw (han et al., ). the prc has abundant natural coal resources (see atwood et al., for clean coal options) and the ‘‘nuclear power’’ option as well to consider in meeting its energy demands. nonetheless, increased capacities from other renewable energy sources are also top on the national policy agenda. as han et al. ( ) note, ‘‘the new reform plan approved on april, , a regulatory committee would be set up to encourage competition and issue licenses to environmentally qualified oper- ators.’’ while sinton et al. ( ) argued for a ministry of energy (moe) where all energy issues would be coordinated, much like the usa department of energy, the prc created the state electricity regulatory commission (serc), which was officially established with the following missions: � developing operating rules for the electric market; regulating operation of the electric market and ensuring fair competition � providing reference of electricity adjustment for national development and reform commission (ndrc) which is in charge of electricity price � regulating and monitoring production quality of power industry � issuing license of and managing production of power industry � managing disputes of power industry � regulating implementation of social public benefit policies (han et al., ). as han et al. ( ) discuss, the ‘‘serc is also the first regulatory commission in the public utilities sector in china. in late , the w.w. clark ii, x. li / utilities policy ( ) – serc set up two regional electricity trade centers on trial basis in northeast china and east china. this is for paving the way towards a competitive national market by forcing energy companies to reduce production costs. in the serc has set up six branches in northern, northeastern, northwestern, eastern, central, and southern regions to supervise power production and marketing activities and carry out relevant administrative jobs. the six offices are located in beijing, the national capital, and five regional centers, shenyang, xi’an, shanghai, wuhan, and guangzhou. these branches are under direct control of the serc. in the past, power prices were distorted because a state monopoly, which controlled half of the nation’s power plants and almost all its grids, tended to buy power off its own plants rather than cheaper alternatives. from the later half of , china also began the work on power price reform, but the work is ongoing. nonetheless, the serc and its offices represent a serious issue for china’s reform of the energy sector. as california experienced during the energy crisis from to , there is a vast difference between the needs of a state, such as california or provinces, cities and autonomous regions in the prc, and the national government in washington dc and beijing respectively (clark and bradshaw, ). there are both inherent conflicts and specific finance, policy and program strategies that can be both conflictual and destructive to both political regions (clark and morris, ). the approach that the prc appears to be taking is far more regionally sensitive, unlike the usa model of a central department or ministry. nonetheless, there are several critical issues confronting the new prc reform structures that need to be highlighted and considered, especially when overall central government energy policy according to a variety of sources (delaguil et al., ; sinton et al., ; han et al., ) includes the need for energy security and independence (china needs to use its own natural resources so as not to be dependent on foreign and unstable supplies), envi- ronmental protection (china wants to reverse pollution and environmental degradation that is causing climate change) and support sustainable development (china advocates environmental protection while encouraging economic development which need to be both balanced and strategic). critical to reform is maintaining these overall policy goals and objectives while implementing and monitoring them at the local and regional levels. in short, the central government needs to maintain a firm and constant oversight position while allowing and encouraging local demands and needs. this is one of the key points of conflict and disagreement in the current asian development bank (adb, ) supported project for energy analysis of inner mongolia autonomous region (imar). the results are not in but a key issue is the debate over local regional autonomy and central government policies. there are global lessons learned from other developed countries in energy (and other) infrastructures due to power crises such as those in california during – and in europe the next year ( ) which all point to reform needed that is neither the status quo (state control of energy) nor de-regulation – privatization – liber- alization (that is, private sector control of energy). . renewable energy finance into agile systems during the past two decades, the chinese power sector has undergone significant structural and regulatory changes. the state- owned single monopoly power company has been unbundled into a number of activity-specific entities. a regulatory body has been established and the reform targets and strategies for the future have been identified and approved by the government. the power sector faces tremendous challenges in terms of capacity expansion to ensure adequate supply of power to the consumers. the possi- bility of power shortage looms large in view of high rate of demand growth, which can be a major threat to the sectoral reform. moreover, the reform has not yet addressed the essential issues of tariffs, ownership of assets and customer choice. while the power sector reform has entered a new phase in china, it has a long way to go before a sustainable industry develops (han et al., ). in february , the national people’s congress, which is the central chinese government, passed the renewable energy law (rel) calling for more ‘‘renewable energy’’ throughout the country. the law would take effect on january . the country has an inadequate supply of electricity with current estimates of billion kilowatts annual shortfall. the demand now but rising is for billion kilowatts. from % to % of all electricity in china is generated by coal and other fossil fuels. implementing regulations will be developed and issued in the fall of . appendix b shows the renewable energy situation in china today (china, ). chadbourne and parke ( ) note that the law creates enor- mous investment opportunities for renewable energy in china. industries in general are divided into three categories by the government depending on priorities: ) encouraged foreign investment industries, ) restricted foreign investment industries, and ) prohibited foreign investment industries. renewable energy is considered the number one area of focus and hence, the central government strongly encourages foreign investment industries. according to the rel, renewable energy is defined as wind, solar, water (most likely to not be hydroelectric or large dams, but instead hydropower mw or less), biomass, geothermal, ocean energy, ‘‘etcetera’’ which was purposely left vague. currently china has established renewable sources in hydropower of , mw, wind of ms and mw of solar power. as a percent of china’s total, renewable energy accounts for only %, which is the lowest among all other asian nations. the annual current rate of renewable consumption is % annually. the target for a national renewable energy goal is to have % of total consumption by , most of which will be from hydropower with a three fold increase. many provinces have set more aggressive goals. article # of rel provides a new ‘‘renewable energy develop- ment fund’’ which will make grants to pay for feasibility studies into projects for rural areas as islands. article # directs chinese banks and other financial institutions to provide low-interest loans from a pre-approved list of ‘‘national renewable energy develop- ment guidance catalog.’’ some projects have already received loans under a ‘‘circular regarding issues on further supporting the development of renewable energy’’ published by the national reform and development commission and the ministry of science (chadbourne and parke, ). at a conference in china (acore, ), an agreement was made between the prc central government and the renewable energy companies in china to seek a renewable energy portfolio standard of % by . one key goal for the government is ‘‘to ensure that renewables projects have an outlet for their output at prices that will make it possible to finance the projects.’’ (chadbourne and parke, : ). the law basically requires a long-term power purchase agreement. the concept is similar to another legal requirement know as a ‘‘mandatory purchase regime for gas and heat (combined heat and power or distributed energy) which can be produced from biological resources. under the new law, the state utilities that control access to the grid will be required to sign interconnection agreements with any renewable projects in their service territories that have received all the government approvals required to start construction (chadbourne and parke, , p. ). w.w. clark ii, x. li / utilities policy ( ) – . lessons learned from california, usa and developed nations the california energy crisis produced many lessons that were learned (clark, a,b, ). these lesson need to be passed on to other developed and developing nations (clark and bradshaw, ) above three critical lessons were noted. first is the need for reform to be clearly defined. and as other nations and states such as california discovered, there needs to be a continuing role that is reflected in the concept of civic market between the public and private sectors. be that role one of creating regulatory schemes, programs or governance, it must be legally defined and in opera- tion. neither market forces alone nor government in-actions can be tolerated in a globally competitive work for key sectors like energy. market manipulation of supply as well as illegal financial actions have stopped most de-regulatory and privatization actions in developed nations (clark and demirag, ). second, there are inherent differences and serious conflicts between the national government and almost all regional, city and states with a nation. california is an excellent example of this. for example, it established a renewable energy standard (rps) of % by . eighteen other states did so as well. but the national government in washington did not and even if it did, the percentage of renewables would be lower for the nation as politi- cians tend to negotiate to ‘‘lower’’, rather than higher regulations and percentages. moreover, california under a new governor even expedited the time frame moving it to . the issue of areas is also regionalism, which goes beyond states versus nations. in the usa, california is part of the western states versus south, middle and eastern regions. each is different. more- over cities, communities and counties are sub-sets of states and provinces have established their own ‘‘green cities’’ alliances and even more aggressive rpss. in southern california, santa monica has declared itself ‘‘green’’ while los angeles has a rps of % by and santa monica will be ‘‘fossil free by ’’. finally, there is the issue of long-term commitment be it in public policy or finance or simply regulations. government and business alike need to know if there will be policies in place along with funding so that they can plan. without long-term financial commitments, neither the public nor private sectors can plan and implement. this key reason why the ‘‘civic market’’ approach to policy making and planning is important as demonstrated by a variety of decisions to get california through its energy crisis (clark and morris, ; clark and bradshaw, ). when clark and lund ( ) first articulated the concept, much theory on public-private partnerships existed. however, few prac- tical examples were explored and rarely put into practice. the california energy crisis provided that need and application. there was no way that the state would get through the crisis without such collaborations and mechanisms. there needed to be consensus through constructive debate, confrontation and dialogue to construct public policies and implement them. . economic themes, strategies as opportunities for renewable energy when lessons learned in developed nation-states are compared, applied and implemented in the prc for example, a number of themes appear. one of the most critical themes is definition of terms and numbers (clark and fast, , ). this is not just a matter of language translation, but even deeper in understanding basic ideas. for example, one of the most often used terms in renewable energy today is ‘‘market’’. the term means different things to different people who are even native speakers of the same language. english speakers from the uk and usa often have different meanings attached to the word, which can be confusing to native language speakers in china and other countries. however, even among native english speakers, the concept has different meanings. for example, many economists see markets as open and free business arenas in which to compete without government inter- ference and regulation. while this is a particular neo-classical economic argument, it does not exist in reality anywhere. the uk and usa are prime examples of promoting this definition of market but practicing something very different. for americans particularly, there are market forces or business that have both economic and political domination in sectors. but more importantly, developed countries like germany, france, the nordic countries and others, have ‘‘government driven markets’’ where goods and services are funded, procured and demonstrated well before the ‘‘mass market.’’ in fact, this ‘‘market’’ model is also true of the usa governments massive debt mechanism used to purchase goods and services, many of which are not and perhaps should not (for military purposes) be on the mass market are clearly a different definition of market than what most economics would expose. clear basic definition of renewable energy generation, technol- ogies, policies and programs are what is needed in any nation-state for providing guidelines in finances, and public policies. the government market provides structure and certainty in its ability to stipulate market rules, regulations and standards in order for the business to respond through procurement, demonstrations and finally mass-market business opportunities. moreover, as noted above, public policies and economic mechanisms of nation-states will differ from one another and within their own regions, cities and communities. nonetheless, ate one level there must be clear and basic definitions. for the prc, there are seven themes that emerge in its efforts to achieve national energy goals. . . social capitalism social capitalism itself is the key theme for the prc and in a different manner by most developed nations (clark and li, ). the exception is that the prc and nordic nations share the same theme in terms of both definitions and policies. in short, social capitalism is conceptualised as a hybrid or combination of the private market mechanisms characterised by the ownership of common industries for the good of all citizens. the three forms of global industrialisation do not reflect this new economic paradigm. when the state considers what it must ‘control’ for the good of all citizens, social capitalism becomes very apparent: water, waste, environment and energy. some social capitalist countries might also argue that medicine and education must be guaranteed to all citizens as well. for example, the current debate in most countries over the telecommunications or digital infrastructure focuses on a similar economic debate: can any country have a ‘digital divide’ between its citizens – the haves and have-nots d dependent on whether someone can afford the technology? the energy crisis in california can be viewed in the same manner: can some citizens (or even businesses and other infrastructure sectors) afford power while others cannot? social capitalism would agree that denying its citizen’s power, for example, based on market or other forces should not exist. definitions of social capitalism are critical for china and other nations. that is why social capitalism in itself represents a para- digm shift: what the social capitalism paradigm argues is, that states or governments cannot be ‘invisible’ or leave certain societal areas w.w. clark ii, x. li / utilities policy ( ) – and sectors open to ‘market forces.’ government must be active and even protective in certain areas that impact on all citizens, including businesses and new enterprises. government’s role is to provide guidance through some regulation, oversight and investment stimulation policies and programs (clark and li, ). basic definitions are one reason why the third theme in renewable energy financing is focused on ‘‘sustainable develop- ment’’ (sd) itself. the concept is often expressed as a key theme but for usa it means a focus on environmental concerns whereas in other nations, it often means economic development. the two concepts and definitions can be totally opposite in practice and a cause of considerable concern. while not reviewing all the defi- nitions of sd, there does appear to be more and more consensus globally (clark and lund, ). . . sustainable development second, sustainable development is very much a comprehensive theme in that like its original usage in the brundtland report ( ); it retains the more general meaning of: ‘the objective of sustainable development and the integrated nature of the global environmental/development challenges pose problems for institutions, national and international, that were established on the basis of narrow preoccupations and compartmentalized concerns.. the challenges are both inter- dependent and integrated, requiring comprehensive approaches and popular participation.’. ‘the concept of sustainable development provides a framework for the integration of environment policies and development strategiesdthe term ‘development’ being used here in its broadest sense. the word is often taken to refer to the processes of economic and social change in the third world. but the integration of environment and development is required in all countries, rich and poor. the pursuit of sustainable development requires changes in the domestic and international policies of every nation.’ ‘as a minimum, sustainable development must not endanger the natural systems that support life on earth: the atmosphere, the waters, the soils, and the living beings.’ . . agile systems a third theme that has arisen in the energy literature is ‘‘agile systems’’ (clark, ). the reform of the energy sector has numerous results. sinton et al. ( ) argue for one model while others propose others for china. if there are lessons learned from the developed nations about reform as being the extreme of de- regulation, privatization or liberalization, for the prc, there are very distinctive results that have already begun to form its own unique energy infrastructure model. for one thing, the prc model is based on its philosophical approach to everything: social capi- talism. that is the concern of every citizen’s social welfare, rather than leaving energy or any sector wide open to private individual or businesses. while this basic approach to energy or any other infrastructure does not follow the developed nation’s, it certainly benefits from their mistakes. the adb ( ) study of imar addresses this issue as did the aba ( ). martinot ( ) makes this point in his analysis of renewable energy in china while lewis ( ) confirms the issues looking at imar specifically. the goal of energy independence or security applies to regions, communities as well as nations. the conflicts and wars today over now increasingly scare natural resources caused by ‘‘peak oil and gas’’ for example are bound to get worse. these costs, let alone those for reversing global warming and climate change (if that is possible) will take an entirely new ‘‘paradigm’’ from that of the developed nations thus far. indicators are that the prc may indeed be the embodiment of that new paradigm to which the developed nations will now follow suit. . . infrastructures infrastructures are a fourth theme that needs to include renewable energy generation in their calculations and systems. models and software need to be used in such calculations. delaquil et al. ( ) used the markal model specifically to look at china’s energy needs. they were able to analyze china for a fifty-five year period of time in terms of energy demands and alternative future scenarios compared to a ‘‘business as usual strategy that relied on coal combustion technologies (no matter how advanced) [which} would not enable china to meet all of its environmental and energy security needs’’ (delaquil, : ). what is interesting about this model and others (see isherwood et al., for the meta net economic model or berry, ; berry et al., ) is that they provide base line data from which to plan. in particular, they look at the variations of needs for infrastructures that include energy along with other structures like water, waste, transportation. the california commission for the st century did that in in order to set goals and strategies for the needs of the entire state (commission, ). more recently, the state did the same thing focused on a hydrogen highway roadmap (california, ). when looking at the financing of infrastructures, the civic market approach is a key organizing and implementation element. from that analytical framework, policy makers can begin to define ideas and strategies which can become part of the planning and implementation process (clark and yago, ). . . renewable energy the fifth theme is renewable energy itself. once defined as solar, wind, geothermal, biomass or whatever, renewables today are created from a variety of sources. more often than not, however, each of these areas is seen as separate technologies (clark, , a,b). wind farms stand alone in large numbers remotely located from the communities that need their power. rarely are renewable technologies combined, linked or operated as hybrid technologies, much like the hybrid cars today: electric combined with gasoline motors. the problem is that the costs of these isolated systems become extremely high. solar and wind, for example are ‘‘intermittent resources’’ requiring storage technologies to make them dependable for base load financial or other monetary calcu- lations (clark and morris, ). a far more economic approach, for example, would be to combine wind and solar power with storage devices or other technology in order to create a base load and hence a constant source of funds (clark and paolucci, ). wind when generated in local commu- nities and combined with other technologies (biomass or storage) becomes economically dependable and financially competitive with fossil fuels (lund and clark, ). a number of studies had analyzed this approach to renewables for financial and environmental protection purposes (aba, ). in remote communities, villages, island nations, or defined urban communities, such distributed systems are cost effective, efficient and environmentally friendly (isherwood et al., ). more recently, some experts and scholars have advocated ‘‘green hydrogen’’ as a hybrid solution that focus on energy storage w.w. clark ii, x. li / utilities policy ( ) – for local power needs today (clark et al., ) while the hydrogen fuel cell car comes to market in as several auto manufacturers have announced. throughout california, green (and others including natural gas reforming) hydrogen stations are coming online and operating. the city of santa monica opened one in mid- june as part of its declaration to be a ‘‘green city’’. . . finance finance is the sixth theme. the place to start with finance is again definitions. while this paper is not intended to review all of literature in economics to define terms, a few critical comments need to be addressed. for one, sustainable development must be defined including its economic component as above. however there are significant other issues that relate specially to finance. consider the strategic planning concepts of short and long-term goals when related to finance. more often than not, few studies define short and long terms as costs and time. this is a serious mistake for many reasons. but the primary one is that the concepts mean different things to different people which will lead to misunderstandings and ultimately to inaction. furthermore, short and long-term need to be defined in order to consider the costs for energy today for the long term. that is a power plant costs today need to be repaid over a long period of time. such finance, either through debt or equity capital means that a region or nation will make a commitment to certain energy generation power plants over others. hence, an energy policy that promotes coal power generation means costs are sunk for decades in this energy source and its technological enhancements (atwood et al., ). this short-term demand, for example, is clear in the increasing worldwide demand for natural gas. the short-term solution (defined as – years) for natural gas is liquefy (liquefied natural gas or lng) it and ship around the world. lng terminals are being proposed and build in almost every area of the world. but that strategy means for regions and nations enormous stranded costs (in the tens of billions) over the long term ( – years) before the facilities are paid for. moreover the communities are now ‘‘energy dependent’’ on fuel supplies that are often not secure and due to increasing demand likely to be volatile and costly. other strategies are far more appropriate for both short and long-term energy generation which do not strand or lock regions and nations into a single and hence costly energy generation infrastructure. renewables are one solution for many reasons. as indicated, the prc appears to be moving in that direction. as a new paradigm, rather than continuing to be dependent on the fossil fuel and conventional central plant paradigm is a significant approach to achieving the national and local prc energy goals and objectives. the use of hybrid technologies for infrastructures (such as green hydrogen stations) as noted above enhances, ensures and makes that short and long-term viable and cost effective. . . knowledge capital the last theme is knowledge capital and concerns the future commercialization of technologies. research and development (r&d) must continue, but become more applied as well through the commercialized and demonstration of technologies for a govern- ment driven market. what that means is that the prc has an opportunity to create new businesses through technologies that are beyond the conceptual and patent period of r&d and ready to be demonstrated in the public sector market. once that is done, and then commercial mass markets will result. this approach to innovation and economic development is exactly what the japa- nese, british, french, germans and americans do but in different ways and to different strategies. for example, due to the bayh–doyle act in the late s, the usa government permitted and encouraged the commercializa- tion of knowledge capital (patents, inventions, publications) from usa tax generated funds for national laboratories, academic researchers and others into the private sector (clark, ). the model had various degrees of success and failure (clark and paolucci, a,b). one of the critical conclusions and lessons learned then was that the government had to be a ‘‘market force’’ and play a role in taking innovation to the mass market (clark and jensen, ). for example, when the american idea of converting public funds to private sector commercialization, the problem was that the government needed to continue to play a ‘‘supportive role’’ (e.g. ‘‘social capitalism’’). some european nations and the japanese in particular had figured that strategy out and been implementing it for decades. what they did was look a government as the ‘‘market driver’’ for innovation. hence, financial structures and mechanisms were put into place including purchase of goods and services from companies demonstrating and commercializing new technologies. after the framework convention on climate change was formed, for example, clark became director of a six-nation study on the transfer of ‘‘environmentally sound technologies’’ from developed to developing nations (clark, , a,b). the focus was entirely on renewable energy technologies and documented the government as the market driver. the finance mechanism for the usa research community was likewise documented as to how intellectual property becomes commercialized. there are many examples over the last ten years about how this social capitalism approach to innovation and technologies can work. but the critical strategy was to link innovation and education. clark and feinberg ( ) produced a ‘‘white paper’’ for the governor of california, titled ‘‘california’s next economy’’ that both identified the upcoming economic development areas and the needs for education and training with specific universities and programs. that paper identified critical areas or ‘‘waves’’ for economic growth in california, of which sustainable development, as new environmental and energy technologies are significant. the other waves are significantly related, such as infrastructures, nanotech- nology, telecommunications, and digital and computing sciences among others. in order for any area to grow, education and training are of prime importance. without an educated workforce as all levels, the new technologies cannot become ingrained in the state and cost effective to civic-markets. . conclusions as opportunities under the social capitalism paradigm, china is able to develop reforms in the energy sector that impact the short and long-term development of its infrastructures. a specific focus on renewable energy in the energy sector means through the rel a sizable financial commitment over many years. this strategy re-enforces the national and local goals of the nation so that renewable energy becomes a significant element in the prc energy infrastructure as well as providing environmental mitigation and reversing global warming and climate change. the paper discussed the need for definitions of concepts, terms and numbers as they mean different things to different people. and it identified seven themes that enable the prc to implement renewable energy projects which meet and even exceed the national energy and environment goals and objectives. appendix b: renewable energy projections w.w. clark ii, x. li / utilities policy ( ) – social capitalism was discussed as the overall theme for the prc but with specific importance to achieving the environmental and energy goals of the nation and its regions. sustainable development is clearly one of the key areas and when defined, it must consider both specific sectors but also be agile and flexible in how energy systems can be financed and implemented. clearly the fourth theme of infrastructures allows renewable energy (theme five) technologies and plans to be hybrids or combined in order to be financed, operated and main- tained more efficiently. the last two areas of finance and knowledge capital are perhaps the ‘‘bottom line’’ in terms of making renewable energy a driving force in the prc. debt and equity funding have now become viable in the prc as long as the government maintains oversight and even considerable ownership in the enterprises. in order for the nation to achieve and exceed its goals, it must provide long-term lead- ership from a government perspective for the private sector to have both confidence and stability. this ‘‘investment’’ from the prc is for the long term (defined as from to years) in which finance and education (knowledge capital) are the most critical themes. appendix a: china’s energy needs appendix c. appendix d. w.w. clark ii, x. li / utilities policy ( ) – references american council on renewable energy (acore). october – , . great wall renewable energy finance conference (gwref), beijing, prc. american bar association (aba), april . renewable energy resources committee and the international energy & resources transaction 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facing the market and competition. international journal of global energy issues ( / ). isherwood, william, smith, j.ray, aceves, salvador, berry, gene, clark ii, woodrow w., johnson, ronald, das, deben, goering, douglas, seifert, richard, january http://www.bth.ca.gov/invest ca/fullreport.pdf http://www.bth.ca.gov/invest ca/fullreport.pdf http://www.governor.ca.gov/hydrogen http://www.governor.ca.gov/hydrogen http://www.lgc.org w.w. clark ii, x. li / utilities policy ( ) – . economic impact on remote village energy systems of advanced technologies. university of calif., lawrence livermore national laboratory [ucrl-id- , published in energy policy, fall, ]. lewis, joanna, april . renewable energy in china, american bar association energy resource subcommittee international teleconference. lund, henrik, clark ii, woodrow w., nov. . management of fluctuations in wind power and chp: comparing two possible danish strategies. energy policy ( ), – [elsevier press]. martinot, eric, april . global renewable energy markets and policies, based on renewables global status report, ren renewable energy policy network (<www.ren .net>), american bar association energy resource subcommittee international teleconference. sinton, jonathan, stern, rachel, aden, nathaniel, levine, mark, may . evaluation of china’s energy strategy options. china sustainable energy program. xinhuanews, . china still in dire need of electricity power in . accessed from: <http://news.xinhuanet.com/english/ - / /content_ .htm> (accessed . . ) [see martinot, eric, renewables: global status report; update. ren , paris, fr, : p. – , focused data on china data and implemented plans, p. – and , – ]. http://www.ren .net http://news.xinhuanet.com/english/ - / /content_ .htm 	‘‘social capitalism’’ in renewable energy generation: china and california comparisons 	background 	renewable energy finance into agile systems 	lessons learned from california, usa and developed nations 	economic themes, strategies as opportunities for renewable energy 	social capitalism 	sustainable development 	agile systems 	infrastructures 	renewable energy 	finance 	knowledge capital 	conclusions as opportunities 	appendix b: renewable energy projections 	references applied physics letters , � � water-soluble multiwall-carbon-nanotube-polythiophene composite for bilayer photovoltaics anthony j. miller,a� ross a. hatton, and s. ravi p. silva nano-electronics centre, advanced technology institute, university of surrey, guildford, surrey gu xh, united kingdom �received june ; accepted july ; published online september � a water-soluble acid oxidized multiwall carbon nanotube �o-mwcnts�-polythiophene composite for bilayer photovoltaics is reported. discrete heterojunction photovoltaic cells utilizing this nanocomposite material as the donor layer exhibit a � % increase in fill factor and commensurate increase in power conversion efficiency as compared to cells without o-mwcnts. crucially o-mwcnts are incorporated into the cell structure using an environmentally compatible solvent without complicating the process of device fabrication. © american institute of physics. �doi: . / . � in recent years a great deal of research effort has focused on the development of organic and hybrid organic/inorganic photovoltaics. the principal motivation is to produce a low cost, renewable energy source which will help to solve the world’s looming energy crisis. progress towards achieving the power conversion efficiencies required for commercial viability has been rapid. however, today’s most efficient devices—which are invariably processed from solution— require the use of environmentally damaging solvents in the fabrication process. , in this letter we report a nanocomposite comprising a homogeneous blend of acid oxidized multiwall carbon nanotubes �o-mwcnts� and the water-soluble polythiophene, sodium poly� -� -thienyl�-ethoxy- - butylsulfonate� �ptebs�. the utility of this material as the donor layer in discrete heterojunction photovoltaic cells em- ploying a c acceptor is also reported. in this context, o-mwcnts facilitate the extraction of positive charge carri- ers, reducing cell series resistance and increasing cell fill factor, resulting in a significant increase in power conversion efficiency as compared to cells without o-mwcnts. impor- tantly, water is used as the solvent to process the nanocom- posite which greatly increases the environmental compatibil- ity of the fabrication process. furthermore, o-mwcnts are integrated into the cell structure without complicating the process of cell fabrication. water-soluble thiophene was purchased from american dye source inc. multiwall carbon nanotubes �� % nano- tube purity� grown by chemical vapor deposition were ob- tained commercially �nanocyl� and used as received. stable dispersions of o-mwcnts in deionized water were prepared by ultrasonically dispersing carbon nanotubes in a : mix- ture of concentrated sulfuric and nitric acids and refluxing at ° c for min before diluting with hplc grade deion- ized water. the resulting dispersion was centrifuged and the acid supernatant decanted off. the remaining solid was re- peatedly washed with hplc grade water over a nm poly- carbonate filter until the washings were ph – . to deter- mine the o-mwcnts loading, a known volume of the stock solution was completely dried and weighed. the typical di- ameter and length of the o-mwcnts after acid treatment a� electronic mail: anthony.miller@surrey.ac.uk - / / � �/ / /$ . , downloaded mar to . . . . redistribution subject to were confirmed using transmission electron microscopy �tem� to be nm and several microns, respectively. all devices were fabricated on indium tin oxide �ito� coated glass �merck� with a nominal sheet resistance of � sq− . ito substrates were cleaned by sonicating in toluene, an aqueous solution of decon- , acetone, and fi- nally refluxing acetone vapor. substrates were microwave oxygen plasma treated before film deposition. o-mwcnts were mixed in %, . %, and . % by weight �wt. %� with ptebs in . m ammonia solution to aid solubility. the ptebs concentration used was . mg ml− and was mixed with the appropriate wt. % of o-mwcnts. the solution was spin coated onto the ito substrates at rpm and then heated in air at ° c for min to expel residual water and ammonia. c � . %� was deposited in a vacuum sys- tem to a thickness of nm. without breaking the vacuum a nm aluminum layer was evaporated through a shadow mask to form the top electrode. film thickness was moni- tored using a quartz crystal microbalance and the photoactive device area was typically . – mm . devices were tested using an oriel solar simulator under am . d spectral illu- mination of mw cm− � sun�. the output power of the simulator was measured using a calibrated thermopile. all measurements were made in air immediately after device fabrication. atomic force microscope �afm� measurements were made under ambient conditions. achieving stable concentrated dispersions of mwcnts in solution requires that they are chemically functionalized. o-mwcnts readily form concentrated aqueous dispersions with ptebs which can be spin cast onto ito glass to form thin films of uniform thickness �as determined by atomic force microscopy�. since o-mwcnts are electrically con- ducting, it is essential that they are confined within the donor layer to avoid short circuiting the device. afm studies of spin coated films of the nanocomposite confirm that the o-mwcnts do not significantly protrude from the film sur- face �fig. �a��. furthermore, the roughness of ptebs and ptebs/o-mwcnts composite films is comparable for all o-mwcnts loadings investigated, evidence that o-mwcnts are uniformly distributed and of the compatibil- ity between ptebs and o-mwcnts. scanning electron mi- croscopy �sem� images acquired using an electron beam en- ergy sufficient to probe the entire film thickness �fig. �b�� © american institute of physics - aip license or copyright; see http://apl.aip.org/apl/copyright.jsp http://dx.doi.org/ . / . http://dx.doi.org/ . / . http://dx.doi.org/ . / . - miller, hatton, and silva appl. phys. lett. , � � confirm that the o-mwcnts are uniformly distributed with the ptebs layer. the absorption spectra of ptebs, o-mwcnts, and ptebs/o-mwcnts composite between – nm are shown in fig. . the absorption spectra of ptebs can be modified by changing the ph of the solution. when the polymer is dissolved in water, absorption is confined to the region below nm having a maximum at nm which corresponds to the �-�* electronic transition. upon reducing the ph an additional peak appears at nm and the solution changes from orange to dark green. the o-mwcnts absorb throughout the measured energy range with a peak maximum at � nm assigned to the �-�* optical transition from the density of states previously identified by ago et al. the composite spectra are the superposition of the o-mwcnts and ptebs spectra, indicating the absence of significant ground state electronic or charge transfer interactions be- fig. . representative afm � � �m � �a� and sem �b� images of ptebs/o-mwcnts � . wt. % � composite films. fig. . absorption spectra between and nm of ptebs, o-mwcnts, and ptebs/o-mwcnts in water. downloaded mar to . . . . redistribution subject to tween the two materials under low white light intensities. the absence of a new peak at nm also indicates that the ptebs is not, to any significant extent, doped by protons associated with the acid functionality on o-mwcnts. table i summarizes values for open circuit voltage �voc�, short circuit current density �jsc�, fill factor �ff�, and power conversion efficiency �pce� for cells with and without o-mwcnts dispersed within the ptebs donor layer. inclu- sion of o-mwcnts within the device structure improves cell fill factor by � % resulting in a commensurate increase in pce. notably the increase in cell ff remains constant over the full range of o-mwcnts loadings investigated herein. both jsc and voc are almost unchanged upon incorporation of o-mwcnts. the large increase in ff upon incorporation of o-mwcnts results from a reduction in cell series resistance, which is evident as an increase in the gradient of the photo- response where it intersects the x axis �fig. �. the cell series resistance is the sum of contributions from bulk transport within the organic layers, carrier extraction at the electrodes, and transport through the electrodes to the external circuit. since the highest occupied molecular orbital �homo� of ptebs � . – . ev� �ref. � and the fermi level of o-mwcnts � . – . ev, ref. and this work� are well aligned, it is likely that the highly conductive o-mwcnts facilitate hole transport through the ptebs layer to the ito electrode. afm measurements of ptebs and ptebs/o-mwcnts films �fig. �a�� show that the roughness is not significantly changed upon incorporation of o-mwcnts into the ptebs layer for all of the loadings investigated. consequently, the small increase in jsc �table i� cannot be attributed to an table i. summary of device characteristics under sun simulated solar illumination. o-mwcnts �wt. %� voc ± . jsc �ma cm− � ff pce . . . . . . . . . . . . . . . . . . fig. . typical current-voltage characteristics of cells with . wt. % o-mwcnts �stars� and without o-mwcnts �squares� dispersed within the ptebs layer. inset: schematic energy level diagram of device structure incorporating o-mwcnts. aip license or copyright; see http://apl.aip.org/apl/copyright.jsp - miller, hatton, and silva appl. phys. lett. , � � increase in the ptebs/c interfacial area. mwcnts are known to quench photoluminescence in conjugated poly- mers, which would be expected to reduce jsc. however, jsc in cells incorporating o-mwcnts is actually slightly increased. one possible explanation is that o-mwcnts do not reduce the photocurrent by quenching excitons formed in the ptebs prior to dissociation, since the homo of ptebs and the fermi level of o-mwcnts are well aligned. alter- natively it may indicate that each o-mwcnts is coated with a ptebs thickness greater than twice the singlet state exci- ton diffusion length, which is typically less than nm in semiconducting polymers. there are two possible explanations for the very small reduction in voc. it has recently been shown that voc in bi- layer organic solar cells is virtually independent of the work function of the hole-extracting electrode. in this case the work functions of the microwave oxygen plasma treated ito electrode and o-mwcnts were measured using ultraviolet photoelectron spectroscopy �ups� to be � . and � . ev, respectively. such a small change in voc would be consistent with this idea. an alternative and more likely explanation is that the o-mwcnts are completely coated with ptebs pre- venting direct contact with the underlying ito electrode. however, since the fermi level of o-mwcnts and the homo of ptebs are well aligned, o-mwcnts facilitate conduction, rather than trapping, holes on their path to the ito electrode. figure shows the typical current-voltage characteristics under sun simulated solar illumination of cells with and without the maximum o-mwcnts loading of . wt. % within the ptebs layer, from which it is clear that the cell shunt resistance is virtually unchanged upon incorporation of o-mwcnts. this is further evidence that o-mwcnts do not contribute to leakage currents across the device. figure �inset� illustrates the proposed energy level diagram for a ptebs:o-mwcnt/c photovoltaic device based on ups measurements of the microwave oxygen plasma treated ito glass and o-mwcnts work functions— . and . ev, respectively—and the previously reported homo and low- downloaded mar to . . . . redistribution subject to est unoccupied molecular orbital energies of ptebs �ref. � and c . in addition to the excellent potential o-mwcnts have to increase the power conversion efficiency of organic solar cells, we anticipate that they may also enhance the mechani- cal strength of these devices, particularly for relatively high o-mwcnts loadings such as those used herein. this is an increasingly relevant property with the growing tendency to- wards fully conformable devices on flexible substrates. in summary we have fabricated discrete heterojunction solar cells using an o-mwcnts:ptebs nanocomposite do- nor layer and c acceptor layer. inclusion of o-mwcnts within the ptebs donor increases cell ff by � % result- ing in a commensurate increase in pce. this improvement in performance is attributed to a reduction in cell series resis- tance resulting from improved hole transport within the ptebs layer. crucially, this composite material is processed from an aqueous solution making it environmentally compat- ible with low cost fabrication for large area devices. the authors would like to acknowledge nicholas p. blanchard for the ups measurements and vlad stolojan for the tem measurements. we would also like to thank the epsrc for funding via a portfolio partnership award. s. shaheen, d. ginley, and g. jabbour, mrs bull. , � �. l. gang, v. shrotriya, j. huang, y. yao, t. moriarty, k. emery, and y. yang, nat. mater. , � �. m. wanli, y. cuiying, g. xiong, l. kwanghee, and a. heeger, adv. funct. mater. , � �. american dye source, http://www.adsdyes.com/products/pdf/ polythiophene/ads p.pdf s. sinnott, j. nanosci. nanotechnol. , � �. f. tran-van, m. carrier, and c. chevrot, synth. met. , � �. h. ago, t. kugler, f. cacialli, w. salaneck, m. shaffer, a. windle, and r. friend, j. phys. chem. b , � �. q. qiao, l. su, j. beck, and j. mcleskey, j. appl. phys. , � �. p. peumans, a. yakimov, and s. forrest, j. appl. phys. , � �. s. khodabakhsh, b. sanderson, j. nelson, and t. jones, adv. funct. mater. , � �. organic photovoltaics concepts and realization, edited by c. brabec, v. dyakonov, j. parisi, and n. s. sariciftci �springer, berlin, �, p. . aip license or copyright; see http://apl.aip.org/apl/copyright.jsp smart window coating based on f-tio -kxwo nanocomposites with heat shielding, ultraviolet isolating, hydrophilic and photocatalytic performance scientific reports | : | doi: . /srep www.nature.com/scientificreports smart window coating based on f-tio -kxwo nanocomposites with heat shielding, ultraviolet isolating, hydrophilic and photocatalytic performance tongyao liu , bin liu , jing wang , linfen yang , xinlong ma , hao li , yihong zhang , shu yin , tsugio sato , tohru sekino & yuhua wang a series of smart window coated multifunctional nir shielding-photocatalytic films were fabricated successfully through kxwo and f-tio in a low-cost and environmentally friendly process. based on the synergistic effect of kxwo and f-tio , the optimal proportion of kxwo to f-tio was investigated and the ft/ kwo nanocomposite film exhibited strong near-infrared, ultraviolet light shielding ability, good visible light transmittance, high photocatalytic activity and excellent hydrophilic capacity. this film exhibited better thermal insulation capacity than ito and higher photocatalytic activity than p . meanwhile, the excellent stability of this film was examined by the cycle photocatalytic degradation and thermal insulation experiments. overall, this work is expected to provide a possibility in integrating kxwo with f-tio , so as to obtain a multifunctional nir shielding-photocatalytic nanocomposite film in helping solve the energy crisis and deteriorating environmental issues. today, energy crisis and deteriorating environmental issues are posing serious threats to the sustainable develop- ment of human society. thus, an increasing number of researches have focused on utilizing green techniques to deal with these aforementioned concerns in the past years – . as a critical component of buildings, windows can lose energy easily. therefore, energy-efficient window coatings are considered to be the important step for reduc- ing heat transfer between the indoor and outside environments. as a novel near-infrared (nir) shielding mate- rial, the tungsten bronze (mxwo ), which is wo doped with monovalent ions such as k+, na, nh + and others, has attracted great attention in recent years , . compared with some transparent thermal insulation coatings like noble metals (ag, au) , black compounds (ruthenium dioxides, rhenium trioxides) , rare-earth hexaborides (lanthanum hexaborides) , , and semiconductor oxides (ito, ato, azo, etc.) – , the nir shielding ability and visible (vis) transmittance of tungsten oxides can be remarkably superior due to the high free electron density, which can be utilized to produce localized surface plasma resonance , . lately, our group have reported that cesium tungsten oxides (csxwo ) powders could be prepared by a water controlled-release solvothermal process with csoh and wcl as raw materials, and it could exhibit excellent visible transparency and broad waveband absorption of to , nm , . however, these raw materials are not environmentally friendly because of the easy hydrolysis of wcl and the volatilization of hcl . to overcome this drawback, the one-dimensional potassium-doped tungsten bronze (kxwo ) powders were successfully synthesized with k wo and k so through the hydrothermal process. the products could shield the nir light with wavelength λ > nm, and this excellent heat shielding property implies that the kxwo might be the potential candidate for the smart window coated materials . if a smart window coating could be developed to not only shield the nir but also degrade harmful pol- lutants, it would have a huge impact on deteriorating environmental issues and present self-cleaning effect department of materials science, school of physical science and technology, lanzhou university, lanzhou, , china. institute of multidisciplinary research for advanced materials, tohoku university, - - katahira, aoba-ku, sendai, japan. the institute of scientific and industrial research, osaka university, japan. correspondence and requests for materials should be addressed to b.l. (email: liubin@lzu.edu.cn) or y.w. (email: wyh@lzu.edu.cn) received: february accepted: may published: june open mailto: liubin@lzu.edu.cn mailto:wyh@lzu.edu.cn www.nature.com/scientificreports/ scientific reports | : | doi: . /srep simultaneously. owing to photocatalytic and hydrophilic properties, semiconductor photocatalysts are widely and frequently employed to purify air and water contaminants , . among various semiconductor photocatalysts, titanium dioxide (tio ) is the most suitable photocatalyst for widespread environmental applications because of its long-term stability against photocorrosion, excellent photocatalytic activity and strong absorption of harmful ultraviolet (uv) light – . due to the fact that a photocatalytic reaction occurs at the interface between catalyst surfaces and organic pollutants, it is highly feasible that the photocatalytic activity of tio is strongly dependent on its surface properties , . based on this speculation, surface-fluorinated tio (f-tio ) has been extensively investigated for its wonderful photocatalytic activity, which could be attributed to the enhanced generation of mobile free • oh radicals on the surface of f-tio . thus, f-tio might be a promising photocatalyst to solve the environmental pollution concerns by relying on its highly efficient solar-light-driven photocatalytic activity . in our recent research, csxwo /zno nanocomposite was prepared as a smart coating for photocatalytic environmental cleanup and heat insulation . despite numerous advantages of this film, the less environmental friendliness of the preparation process and the instability of zno are in urgent need to be solved , . in this work, a series of multifunctional nir shielding-photocatalytic nanocomposite films were fabricated successfully through f-tio and kxwo . in these smart coatings, kxwo plays a part in shielding most of nir light and holding high vis light transparency, while f-tio acts as both a photocatalyst to degrade harmful organic pollut- ants and a barrier to shield harmful ultraviolet light, which makes up the shortage of kxwo in the uv region. it’s worth mentioning that the kxwo nanorods were synthesized with na wo as tungsten source instead of k wo , which is considered as a lower-cost way than previously reported method of preparing tungsten bronze powders , . furthermore, the heat-shielding and photocatalytic property of f-tio -kxwo nanocomposite films were evaluated and compared with that of ito or p film to find out the optimal ratio of kxwo to f-tio with a synergistic effect. results and discussion as shown in fig.  , xrd analysis has been employed for analyzing the crystalline phase of samples. the reflection in fig.  a matches best with the single anatase tio (jcpds - ) phase, while the main peaks at θ values of . o, . o and . o can be indexed respectively to ( ), ( ) and ( ) crystal planes, which are readily indexed to the pure potassium tungsten bronze (k . wo ; jcpds - ), as displayed in fig.  b. furthermore, with the increasing content of f-tio , the intensities of the tio peaks are increased obviously (fig.  c–g), reveal- ing that ft-kwo nanocomposites are obtained successfully during the hydrothermal process. meanwhile, peaks related to other phases are not observed in the synthesized samples, indicating that the f-tio have not reacted with the kxwo . the morphology of the as-prepared samples was characterized by sem, which is shown in fig.  . as shown in fig.  a,b, the pure f-tio is nanoparticles with relatively uniform size and the as-prepared kxwo powders exhibit smooth surface, regular nanorods with size of about – nm, which are corresponding to that of products synthesized with k wo and k so . figure  c shows the sem image of kxwo samples after the introduction of the f-tio , and it could be clearly seen that f-tio particles are attached to the surface of kxwo nanorods, indicating the intimate contact between f-tio and kxwo . the inset in fig.  c shows the sem image of ft/ kwo film at o, and the thickness of the film can be calculated to be about . μ m, according to the equation: t = t’ × sin θ . where t’ is the thickness shown in sem image (t’ = . μ m) and θ is the view angle (θ = o). in addition, edx analysis confirms the distribution of ti, o, f elements in f-tio samples and k, w, o elements in kxwo samples as shown in fig.  d,e, respectively. as for ft/ kwo nanocomposites (fig.  f ), it reveals the coexistence of ti, o, f, k, and w elements as expected, which also indicates the existence of f-tio and kxwo in ft/ kwo nanocomposites. furthermore, according to edx quantification (insert fig.  f ), the atom percentages of ti and w for the as-synthesized ft/ kwo nanocomposites are . % and . %, and the atom ratio of ti to w is approximately . , which is very close to the nominal value (ti: w = . ). in addition, figure . xrd patterns of pure (a) f-tio , (b) kxwo and different ft-kwo nanocomposites: (c) ft/kwo, (d) ft/kwo, (e) ft/kwo, (f) ft/ kwo, (g) ft/ kwo. www.nature.com/scientificreports/ scientific reports | : | doi: . /srep the ti: w ratios are corresponding with the nominal ratios in all ft-kwo nanocomposites as displayed in fig. s , indicating that the elementary composition is well controlled by the experimental conditions. to further obtain the microscopic morphology and structure information, the tem and hrtem analysis of as-synthesized ft/ kwo nanocomposites have been performed, as shown in fig.  . the tem images of ft/ kwo nanocomposites (fig.  a,b) show the specific rod-like morphology with some nanoparticles attached, which is in accordance with sem results. moreover, the hrtem image of the magnified view is given in fig.  c. the distance of . nm and . nm between the adjacent lattice fringes can be assigned to the ( ) plane of hexagonal kxwo and the ( ) plane of anatase tio nanocrystals, respectively. obviously, the ft/ kwo nano- composites are formed with favourable nanosizd interfacial contact so as to exhibit multifunctional properties of nir shielding and photocatalytic degradation. the chemical composition of the ft/ kwo nanocomposite particles was also examined by xps. the full range xps spectra are presented in fig. s a. peaks at binding energies corresponding to ti, o, f, k, and w are clearly distinguished and no extra elements except carbon can be found in the spectra. the w f core-level xps spectra of the as-prepared ft/ kwo samples exhibit detailed information on the chemical state of core level tungsten, as shown in fig. s b. there are two spin-orbit doublets in this spectrum, which is attributed to w f / and w f / : the peaks at . ev and . ev are attributed to w +, while the peaks at . ev and . ev are assigned to w +, which reaches a good agreement with the reported results. meanwhile, the atomic contents of ti and w in ft/ kwo were calculated from xps and found to be . at. % and . at. %, corresponding to the nominal value (ti: w = . ). it is suggested that the non-stoichiometric potassium tungsten bronzes are reduced compounds, and the co-existence of w + and w + is the necessary condition for the nir shielding performance . to study optical properties of the samples, the transmittance spectra of the as-prepared films are shown in fig.  . for the pure kxwo film (fig.  g), a great nir shielding performance at the range of to nm was observed, which could be closely related to the plasmon resonance of free electrons, interband transition and small polarons . however, the visible light transparency and absorption of ultraviolet region (see inset in fig.  ) are defective. on the contrary, these phenomena above are absent in the case of the film of pure tio displayed in fig.  a, which exhibits no nir shielding ability but excellent ultrviolet light absorption (see inset in fig.  ) and high visible light transparency capability as a result of the narrow band gap of tio . as expected, all of the figure . sem images of (a) f-tio , (b) kxwo , (c) ft/ kwo nanocomposites; edx spectra of (d) f-tio , (e) kxwo , (f) ft/ kwo nanocomposites. the insets in (c) shows sem image of ft/ kwo films (at o angle view). www.nature.com/scientificreports/ scientific reports | : | doi: . /srep ft-kwo nanocomposite films retain all advantages of tio and kxwo films in the range of uv, vis and nir. the inheritance of nir absorption capability of composite could be attributed to the use of soft chemical method in synthesizing ft-kwo nanocomposite films in which the reduced w + ion was preserved. specifically, with an increase in the kxwo content, the nir shielding property becomes more pronounced while the visible light transmittance and uv shielding capability decreased. even so, there will be a ft-kwo nanocomposite film with an appropriate mass ratio of f-tio to kxwo , exhibiting a great synergistic effect on blocking nir and uv light as well as transmitting most of visible light. on the basis of the aforementioned optical properties of ft-kwo nanocomposite films, it is reasonable to suggest that these films show great potential for application as nir shielding films. a thermal insulation experi- ment has been carried out in a sealed box. figure  exhibits the inner temperature variation upon irradiation time and cooling time, and the temperature variations between the initial and final temperature are listed in table s . as shown in fig.  a, it’s obvious that the temperature increases significantly with irradiation time when the box is covered with blank or f-tio coated glass, which proves that the f-tio film has no nir shielding capacity as displayed in fig.  a. notably, the heating rates of glasses coated with ft-kwo nanocomposites are much lower than those of box covered with the blank or f-tio coated glass, and the heating rate inside the box decreased dis- tinctly with an increase in the kxwo content. for example, within min irradiation, the temperature variation of box covered with ft/kwo nanoparticle film coated glass is . °c, while that of box covered with ft/ kwo film coated glass is depressed to . °c. in addition, the temperature variation curves with cooling time (fig.  b) show similar tendency as discussed above, that is to say, all of the ft-kwo nanocomposite films show good ther- mal insulation performance. moreover, the temperature variation between the initial and final temperature slows figure . (a) low-, (b) high-magnification tem images and (c) hrtem images of as-synthesized ft/ kwo nanocomposites. figure . transmittance spectra of (a) pure f-tio , different ft-kwo nanocomposites: (b) ft/kwo, (c) ft/kwo, (d) ft/kwo, (e) ft/ kwo, (f) ft/ kwo and (g) pure kxwo films. the inset shows the absorption spectra of different powders with the wavelength from nm to nm. www.nature.com/scientificreports/ scientific reports | : | doi: . /srep down with the increasing content of kxwo , as displayed in table s . the relatively slow heating rates during the heating and cooling time indicate the ft-kwo nanocomposite films have great thermal insulation capacity. the ito glasses are widely used and well-known as effective nir shielding material, as a control, the simulated exper- iment was carried out by irradiating the sealed box covered by ito, ft + kwo (mechanically mix f-tio and kxwo ), ft@ kwo (f-tio film coating on the top of kxwo film) and kwo@ft (kxwo film coating on the top of f-tio film) coated glass, respectively, and the temperature changes inside the boxes are plotted in fig. s a. by comparison, the box covered with the ft/ kwo film coated glass exhibited a slight lower temperature gradient than the box covered with other coated glasses both during the period of heating (fig. s a) and cooling (fig. s b). this phenomenon is corresponding to the transmittance spectra inserted in fig. s a. the results indicate superior thermal insulation capacity and potential practical application of the ft-kwo nanocomposite film. in order to confirm the photocatalytic activities of ft-kwo nanocomposite films, the degradation of mo by various films was carried out under the irradiation of uv light. as shown in fig.  a, f-tio film exhibited high photocatalytic activity and % of the initial mo decreased after min, whereas the kxwo film shows almost no effect on the degradation. fortunately, these nanocomposite films are highly efficient for photocatalytic degradation of organic pollutant and the photocatalytic activity will be enhanced with the increase of f-tio content in ft-kwo nanocomposites. for example, about % of the initial mo molecules are decomposed by the ft/kwo nanocomposite film, while in comparison, only % by the ft/ kwo film within min. based on previous studies, the degradation of dyes can be ascribed to a pseudo-first order reaction with a langmuir– hinshelwood model when the initial concentration of dye solution is small: ln (c /c) = kt . where c is the con- centration of mo after t min degradation, c is the initial concentration of mo, and k is the first-order reaction rate constant. figure  b exhibits the plots of ln (c /c) versus irradiation time. unusually, the ft/ kwo film exhibits similar photocatalytic activity to ft/kwo film where the k of ft/kwo is only about . times than that of ft/ kwo. meanwhile, considering the temperature variation curves displayed in fig.  , the thermal insula- tion capacity of ft/ kwo film has gained a noticeable improvement than that of ft/kwo film. in other words, the ft-kwo film shows the best multifunctional properties when the mass ratio of f-tio to kxwo is : . to further investigate the advantages of ft-kwo nanocomposite film, as a comparison, the photocatalytic activities of p , ft + kwo, ft@ kwo, kwo@ft and f-tio ’ (where the f-tio content in this film is equal to that of ft/ kwo film) films were measured under the same condition. as displayed in fig. s , the photocatalytic figure . the inner temperature dependence on (a) irradiation time and (b) cooling time curves of sealed box covered with different films coated glass. figure . (a) variation of mo concentration against irradiation time using f-tio film, ft-kwo nanocomposite films with various kxwo contents and pure kxwo film under ultraviolet light irradiation and (b) plots of ln (c /c) versus irradiation time for mo representing the fit using a pseudo-first-order reaction rate. www.nature.com/scientificreports/ scientific reports | : | doi: . /srep activity sequence of these films is ft/ kwo ~ p > ft + kwo > f-tio ’ ~ ft@ kwo > kwo@ft and the enhancement of the photocatalytic activity could be attributed to the close interfacial contact and strong interaction between f-tio and kxwo in ft/ kwo film. besides, the introduction of kxwo with excellent electronic conductivity can promote the photogenerated electron transport to the surface of the composite more easily, thus inhibiting the recombination between photogenerated electrons and holes , , . however, when it comes to ft + kwo film and others, the f-tio and kxwo are independent (see sem image inset fig. s ) to generate nearly no synergistic effect. it is abnormal that only % of the initial mo molecules are decomposed by kwo@ft nanocomposite film within min, which might be attributed to the covered surface of f-tio limits the photocatalytic reaction to some extent . in conclusion, these results mentioned above further confirm that the ft/ kwo nanocomposite film is effective for photocatalytic degradation of organic pollutant and very promising for practical application in smart window. in consideration of the practical application of these nanocomposite films, the photocatalytic stability of the as-prepared ft/ kwo nanocomposite film was further investigated by the cycle experiment. as shown in fig. s a, the photocatalytic activity of the ft/ kwo nanocomposite film remains still unreduced after four con- secutive cycles, thus indicating the good stability of the film during the photocatalytic experiment. furthermore, the thermal insulation capacity of the ft/ kwo film after the fourth photocatalytic experiment was investigated and exhibited in fig. s b. it is clear that the temperature variation of box is about . °c (fig. s b- ) when it was covered with the ft/ kwo film coated glass after the fourth photocatalytic experiment, which is slightly higher than that of new ft/ kwo film coated glass (fig. s b- ), but much lower than that of blank glass (fig. s b- ). it thus indicates the great reusability of the ft-kwo nanocomposite films. to identify the surface hydrophilic properties of the nanocomposite films, the contact angle (ca) value of the as-prepared ft/ kwo film was measured and compared with that of pure tio , kxwo film, as shown in fig.  . notably, the ca value of kxwo film (ca = . ) is significantly higher than that of f-tio film (ca = . ), which indicates the f-tio film has good hydrophilic property. meanwhile, the ca value of ft/ kwo film (ca = . ) has not been affected by the introduction of kxwo and the similar ca values between f-tio film and ft/ kwo film reveal the hydrophilic nature of prepared ft/ kwo film. interestingly, the ca value of ft/ kwo film decreased to . ° after the fourth photocatalytic experiment, as displayed in fig.  d. this phe- nomenon could be attributed to the photoinduced hydrophilicity caused by reconstruction of surface hydroxyl groups , . the above results confirm the ft/ kwo film is advantageous for applications in antifogging and self-cleaning coatings. a working model illustrating the multifunctionality of the ft-kwo and f-tio coated window is summa- rized in fig.  . obviously, this smart window plays different roles in various conditions. in summer days, the ft-kwo film side towards the outside; with the irradiation of the solar light, the smart window can not only block most of the nir lights for heat preservation and keep cool indoor, but also isolate harmful uv light and transmit vis light. in winter days, this window should be rotated ° to make the ft-kwo film side towards the inside. in this case, the smart window not only reduces heat loss from inside to outside, but also blocks uv light and transmits vis light effectively. meanwhile, the high hydrophilic capacity can control the production of water vapour on the window and enhance the visibility availably. to sum up, this smart window will minimize the usage of air conditioning and heaters to control the redundant electricity consumption and promote the solution of energy crisis. in addition, both sides will absorb uv light to motivate photocatalytic reaction owing to the exist- ence of f-tio , so as to degrade the harmful organic air pollutants and help solve the environmental issues subtly. in summary, the f-tio -kxwo multifunctional nanocomposites have been fabricated successfully through a low-cost and eco-friendly method. moreover, the ft-kwo films exhibited excellent multifunctional perfor- mance of nir, uv light insulation, vis transparency and photocatalytic activity. a competitive relation was observed between f-tio and kxwo : the photocatalytic activity will be decreased while the thermal insulation figure . contact angle of a water drop in air on new (a) f-tio , (b) kxwo , (c) ft/ kwo films and (d) ft/ kwo film after the fourth photocatalytic experiment. www.nature.com/scientificreports/ scientific reports | : | doi: . /srep performance improved with the increase of kxwo content in ft-kwo nanocomposite films. as the optimal proportion of kxwo to f-tio , the ft/ kwo nanocomposite film shows a significant multifunctional property of outstanding nir, uv light shielding performance, high photocatalytic activity on degradation of harmful organic pollutants and excellent hydrophilic capacity. it is worth mentioning that its thermal insulation capacity is better than that of ito, while the photocatalytic activity is surpassing p . therefore, ft-kwo nanocomposite film could have great potential applications as smart windows coating material, so as to help solve the energy crisis and deteriorating environmental issues in a convenient way. methods preparation of kxwo nanorods. kxwo nanorods were synthesized on the basis of a procedure reported previously. all reagents were of analytical grade and used without further retreatment. specifically, . g na wo · h o and . g k so were dissolved in ml deionized water under magnetic stirring followed by adding mol/l hcl to adjust ph to . . after that, the resultant solution was transferred into a dried teflon-lined autoclave with ml internal volume and kept it at °c for h. after natural cooling to room temperature, the intermediate products were obtained after being washed with water and ethanol for three times respectively and dried at °c overnight. finally, a certain amount of as-prepared samples was reduced in h ( vol %)/n atmosphere at °c for h to obtain the potassium tungsten bronze. preparation of ft-kwo nanocomposites. the as-prepared kxwo nanorods were redispersed via the assist of ultrasonication in ml deionized water to obtain the homogeneous suspension. then, . g nh hf and . ml absolute ethyl alcohol with . ml tetrabutyl titanate (tbot) were added dropwise to the suspen- sions under vigorous stirring for min. finally, the above suspensions were transferred into ml teflon-lined autoclaves and maintained at °c for h. after this hydrothermal reaction, the suspensions were centrifuged at rpm followed by washing with distilled water and ethanol twice, and then dried in an oven at °c for h. the nominal contents of kxwo additives were wt.%, wt.%, wt.%, wt.% and wt.%, respec- tively for the ft-kwo nanocomposites. these samples are labelled as ft (f-tio )/kwo (kxwo ), ft/kwo, ft/kwo, ft/ kwo, and ft/ kwo, respectively. for comparison, pure f-tio and kxwo were synthesized under the same condition. preparation of ft-kwo nanocomposite films. the nir shielding and photocatalysis properties of f-tio -kxwo nanocomposites were evaluated by coating them onto quartz glass substrates ( cm* cm* mm). in a typical film synthesis process, . g samples were dispersed into a mixed solution with . g collodion and . g absolute ethyl alcohol under magnetically stirring, thus forming homogeneous colloidal dispersions. subsequently, the above slurries were spin-coated on the quartz glass substrates at rpm for s, rinsed with absolute ethyl alcohol and dried at °c for min. for comparison, the p , ito and blank films were prepared under the identical conditions. in addition, the synthesis process of other films was presented in the supporting information. characterization. the phase purity of samples was analyzed by x-ray powder diffraction (xrd) using a bruker d phaser x-ray diffractometer with graphite monochromator using cu kα radiation (λ = . Å) at room temperature. the morphology of the sample and the energy dispersive x-ray spectroscopy (eds) spec- trum were detected by field emission scanning electron microscopy (fesem, hitachi, s- ). moreover, the transmittance of films was measured with a perkin elmer spectrometer. besides, transmission electron microscopy (tem) and high-resolution transmission electron microscopy (hrtem) images were collected on an f s-twin electron microscope (tecnai g , fei company). x-ray photoelectron spectroscopy (xps, phi- , physical electronics) was performed using a monochromated al ka irradiation. the chamber pressure was ~ × − torr under testing conditions. the surface hydrophilic properties of the as-prepared films were figure . the working model of the ft-kwo and f-tio coated window applied to different conditions. www.nature.com/scientificreports/ scientific reports | : | doi: . /srep characterized by detecting the water contact angle measured by a contact angle meter (jc c) with μ l water droplet under ambient conditions. evaluation of nir shielding property. to evaluate the thermal insulation properties of ft-kwo nano- composite films, a simulated room was built with a sealed plastic box ( cm* cm* cm) covered with different films coated glasses under the irradiation of a w infrared lamp. the experiments were carried out at the room temperature of °c and temperature variation was monitored by a thermodetector with four thermocouples every ten minutes. meanwhile, the heat preservation performance of these films was evaluated in the same plastic box without the irradiation of infrared lamp, but the glasses were rotated ° to make the ft-kwo film side toward the inside with the initial temperature being °c. evaluation of photocatalytic activity. the photocatalytic activities of the ft-kwo nanocomposite films were evaluated by measuring the degradation ratio of methyl orange (mo). the initial concentration of mo solution was mg/l− , and the quartz glass substrate coated with ft-kwo nanocomposite film was immersed in ml mo solution. a w high pressure hg lamp was employed for the ultraviolet irradiation source and positioned cm away from the reactor to trigger the photocatalytic reaction. in addition, a certain volume of mo solution was withdrawn at selected times and analysed by measuring the light absorption of the clear solution at nm (λ max for mo solution) using a spectrophotometer (lg- sp). references . ong, w.-j., tan, l.-l., chai, s.-p., yong, s.-t. & mohamed, a. r. facet-dependent photocatalytic properties of tio -based composites for energy conversion and environmental remediation. chem sus chem , – ( ). . yue, d., you, f. & darling, s. b. domestic and overseas manufacturing scenarios of silicon-based photovoltaics: life cycle energy and environmental comparative analysis. solar energy , – ( ). . wang, w. et al. monoclinic dibismuth tetraoxide: a new visible-light-driven photocatalyst for environmental remediation. applied catalysis b: 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nanocomposite. journal of nanoscience and nanotechnology , – ( ). . yu, h., tian, j., chen, f., wang, p. & wang, x. synergistic effect of dual electron-cocatalysts for enhanced photocatalytic activity: rgo as electron-transfer mediator and fe(iii) as oxygen-reduction active site. sci rep , ( ). . tang, j., quan, h. & ye, j. photocatalytic properties and photoinduced hydrophilicity of surface-fluorinated tio . chemistry of materials , – ( ). . sakai, n., fujishima, a., watanabe, t. & hashimoto, k. quantitative evaluation of the photoinduced hydrophilic conversion properties of tio thin film surfaces by the reciprocal of contact angle. the journal of physical chemistry b , – ( ). . sakai, n., fujishima, a., watanabe, t. & hashimoto, k. enhancement of the photoinduced hydrophilic conversion rate of tio film electrode surfaces by anodic polarization. the journal of physical chemistry b , – ( ). acknowledgements this research was supported by the international sci. & tech. cooperation foundation of gansu provincial, china (grant nos wkca and wcga ), the national science foundation for fostering talents in basic research of national natural science foundation of china (nos and ), the national natural science funds of china (grant no. ) and the network joint research center for materials and devices, the grant-in-aid for science research (no. ). author contributions t.l. and b.l. conducted the most of investigation for the samples. t.l. wrote the main paper. b.l. designed the concept and the experiment method of the research. b.l. and y.w. supervised the project, had given valuable advices on the proceeding of this work and revised the manuscript. s.y., t.s. and t.s. had provided precious suggestions on the selection of tungsten bronze as nir shielding materials. j.w., y.z. and l.y. supported the characterization of the samples. h.l. and x.m. revised the manuscript. all authors discussed the results and commented on the manuscript at all stages. additional information supplementary information accompanies this paper at http://www.nature.com/srep competing financial interests: the authors declare no competing financial interests. how to cite this article: liu, t. et al. smart window coating based on f-tio -k xwo nanocomposites with heat shielding, ultraviolet isolating, hydrophilic and photocatalytic performance. sci. rep. , ; doi: . / srep ( ). this work is licensed under a creative commons attribution . international license. the images or other third party material in this article are included in the article’s creative commons license, unless indicated otherwise in the credit line; if the material is not included under the creative commons license, users will need to obtain permission from the license holder to reproduce the material. to view a copy of this license, visit http://creativecommons.org/licenses/by/ . / http://www.nature.com/srep http://creativecommons.org/licenses/by/ . / 	smart window coating based on f-tio -kxwo nanocomposites with heat shielding, ultraviolet isolating, hydrophilic and photocatalytic performance 	introduction 	results and discussion 	methods 	preparation of kxwo nanorods 	preparation of ft-kwo nanocomposites 	preparation of ft-kwo nanocomposite films 	characterization 	evaluation of nir shielding property 	evaluation of photocatalytic activity 	additional information 	acknowledgements 	references application/pdf smart window coating based on f-tio -kxwo nanocomposites with heat shielding, ultraviolet isolating, hydrophilic and photocatalytic performance srep , ( ). doi: . /srep tongyao liu bin liu jing wang linfen yang xinlong ma hao li yihong zhang shu yin tsugio sato tohru sekino yuhua wang doi: . /srep nature publishing group © nature publishing group © macmillan publishers limited . /srep - nature publishing group permissions@nature.com http://dx.doi.org/ . /srep doi: . /srep srep , ( ). doi: . /srep true microsoft word - urban component of the energy crisis . .docx munich personal repec archive the urban component of the energy crisis pareto, vittorio emmanuel and pareto, marcos pompeu online at https://mpra.ub.uni-muenchen.de/ / mpra paper no. , posted mar : utc electronic copy available at: http://ssrn.com/abstract= electronic copy available at: http://ssrn.com/abstract= the urban component of the energy crisis vittorio e. pareto, ph.d. marcos p. pareto august electronic copy available at: http://ssrn.com/abstract= electronic copy available at: http://ssrn.com/abstract= abstract the spiral of higher oil prices that is occurring currently is mostly caused not by the lack of reserves, but by increasing demand on the existing supply. however, increase of supply would only temporarily attenuate the issue, as demand is expected to continue to soar and eventually outstrip the reserves of fossil fuels, which combined account of almost all our present energy sources. it is not that fossil fuels will disappear, but rather the certainty that they will become progressively scarcer and definitely more expensive as time goes by, has become an irreversible and well established trend. the cost increase of a critical resource – energy - will force unforeseen changes in production and in distribution of goods, affecting the whole productive matrix – including employment. not only new products and distribution systems based on higher energy costs will need to be conceived and implemented but especially the current reliance on fossil fuels - oil, gas and coal - will need to be replaced almost entirely by sustainable sources - an extraordinarily complex enterprise that should consume our efforts in the next years. energy consumption will be further aggravated by the expected . billion population increase from now to , which is expected to be almost entirely concentrated in the urban centres of asia, latin america and africa. since these additional urban spaces are still to be developed, urban development strategies that consider higher energy costs could effectively alleviate the transition period from fossil fuels to sustainable sources. rather than providing a recipe for urban planning, this paper stresses the need for further research to incorporate the energy cost component with the urban development context and the dissemination of information on this matter. . introduction among the current financial and economic crisis, and sometimes thought to be derived from it, a fundamental change is taking place, caused by the unsustainability of the current production and transportation systems, which were developed based on the easy availability of cheap fossil fuels. the current abrupt increase of fuel prices is not a result of a conjunctural event but a dramatic symptom of a failing supply of energy. cheap energy was one of the main factors that allowed the explosive economic development that occurred during the last century, especially since the end of the wwii. unfortunately, that phase seems to be over. to maintain the world development process, a new balance has to be found between the new production and distribution profiles, taking into account the energy factor. this is a normal event in the development process yet in this case will affect almost all the productive system simultaneously and our consumption habits at an extremely fast pace. it is the speed of change the real issue we have to cope with. this paper intends to discuss the main factors of the energy crisis, why it is happening now and how urban development planning can contribute to alleviate the transition period. rather than being conclusive, it proposes some lines of research that should be explored in the near future to support urban planning and development, adding the energy aspect to the conventional physical, economic and social components of urban planning. . the energy supply issue the world reserves of raw materials are the total amount of these materials that are physically, technically and economically available under present conditions, i.e. that can be placed in the market at the current price structure. under these criteria, the total world reserves of fossil fuels are assumed to be around billion tce of natural gas, billion tce of mineral oil, shale and liquid gas, and billion tce of coal (all forms), adding up to the impressive amount of , billion tce. on the other side is the world’s consumption rate, which is currently around billion tce (rwe - world energy report ). in other words, if consumption remains at the same level (no economic development - no population growth scenario), the present reserves would be enough to last almost until the end of this century at the current prices. tce – tonne of coal equivalent. energy generated by burning metric ton of coal, equivalent to the energy obtained by burning . barrels of oil ( kg), m³ of natural gas ( . million btu) or . mwh. oil, gas and coal – which together provide % of the world’s energy – are convenient, powerful and, until now, still cheap to obtain. all other forms of generating energy – from nuclear to hydro, solar, wind and others do not weight much on global terms. more precisely, oil accounts for %, gas % and coal % of the world energy consumption. nuclear and hydro provide only % each, while all other sources combined provide less than %. liquid fuel alternatives such as shale oil, extra-heavy oil, bio-fuels (mainly ethanol and bio-diesel), liquefied coal or gas are expected to become increasingly competitive in the near future, as conventional fuels reach higher price levels. their supply is expected to grow from . to . million barrels per day from to . yet all these alternative sources combined are not expected to account for more than % of the liquid fuel demand in . the availability of fossil fuels as our main source of energy is limited by technical and economical factors. in principle neither oil, nor gas and coal will ever be physically totally exhausted. yet as the easier and cheaper options to find and explore are used, extraction costs increase while the amount produced tends to be relatively smaller. for those reasons, reserves of fossil fuels are measured in terms of their economic availability under present conditions (rwe , eia ). it should mentioned that there are also enormous quantities of “resources”, a term given to fossil fuel deposits that are not considered reserves, because they are not feasible to explore under the current price structure. it is clear that some of these resources may eventually become reserves as prices go up and new exploration techniques are developed. yet one should also consider that deposits with low yield and difficult extraction consume an increasing amount of energy to be transformed into fuel, effectively reducing their net energy content (rwe ). as energy prices increase, lower yield resources are upgraded to economically feasible reserves, even if no new findings are made. the critical point is when the demand equals the production capacity – the “peak”. when this happens, higher prices constrain the demand, and simultaneously allow a boost in reserves, inducing an increase in supply until in due course a new peak is attained. as global reserves are used, the inter-peak periods tend to shorten and, if no alternative sources are ready take over, a supply collapse is possible. such scenario could bring a worldwide fuel shortage of unpredictable consequences. therefore the critical issue is not when the existing reserves of fossil fuels would end – in principle they will continue to be available as prices increase – but the peak. according to some experts, oil has already started to peak (hubbert, ; deffleyes, ). gas and coal reserves are bigger than oil, so the latter will tend to be progressively replaced by the former, which should attenuate a price explosion. nevertheless this process will push energy prices higher, until sustainable sources replace our dependency on fossil fuels as major source of energy. higher energy prices will make alternative sources of energy economically feasible. yet two additional issues still have to be considered: first of all, the time lag and the resources needed to tap these alternative sources and bring up production to balance the reduction in supply of fossil fuels. secondly, the fact that industrial production and transportation costs will by definition be higher, bringing in a possible recessive trend with a consequent drop in living standards until higher performance and efficiency and technological improvements can outweigh the higher production and distribution costs. secondly, the fact that industrial production and transportation costs will increase as energy costs rise, bringing in a possible recessive trend with a consequent drop in living standards. such situation may prevail until higher efficiency and technological improvements can outweigh the higher production and distribution costs. various apocalyptic scenarios have been built under the assumption of massive shortages of essential resources such as food or energy, ranging from malthus’ population study to the seminal limits to growth (meadows, and ). while significant advances in technology and production efficiency have prevented catastrophic scenarios from happening, their warnings are sobering and cannot be dismissed. what are the alternatives? uranium reserves, based on production prices of up to $ /kg, are only about billion tce. yet, contrariwise to fossil fuels, the cost of uranium ore is an insignificant part in the cost of energy produced – only about . cent/kwh, about - % of the production cost. it has been estimated that if the price of extraction and concentration reached higher levels – even to the extreme of $ , /kg - the availability of uranium as fuel would become virtually endless while the fuel cost would still remain a minor component of nuclear energy. the use of more advanced reactors and breeder technology can further contribute to lower costs and limit fuel demand (hopf ). the energy issue is neither the technology nor the potential availability – the critical issues are the logistic factors required to replace fossil fuels by other sustainable sources within a -year period. such effort – necessary to avoid a major energy crisis - requires a serious commitment of capital, human resources, industrial organization and last but not least, political will. estimates indicate that to supply two thirds of the foreseen demand for energy would require the construction of about two hundred nuclear power plants per year, each taking over five years of construction before becoming productive , although adoption of standard design and equipment could probably shorten the development period and reduce costs. (murkeheide ). renewable sources, such as solar, wind power or geo-thermal should become increasingly competitive as energy costs rise and have an endless availability. yet not only is the current production insignificant, but any massive worldwide conversion to such ecological sustainable sources seems implausible within the available time frame for replacement. furthermore, the energy from these sources is complementary to energy from conventional plants (uranium, hydro), requires specific conditions to work and is more expensive to implement. hydroelectric production is expected to increase and share with nuclear and gas-driven plants most of the sources for electric energy in the near future (rwe ). it seems clear that high oil prices will reduce oil consumption and at the same time constrain development, which is one of the main forces pushing higher consumption. at the same time, high oil prices will stimulate the use of alternative and renewable sources. yet it should be clear that not only is cheap energy from oil gone, but that the time lag until sustainable sources can become significantly productive - such as producing bio-fuels, building hydro-electric dams and nuclear plants - will constrain energy availability for some time, regardless of the scenario considered. replacing two-thirds of energy production from fossil fuels to other sources by would require building about , . mw power plants, at a cost of about . billion each – regardless of using nuclear, hydro, wind or other sustainable energy source. it is assumed that by both gas and oil will be too costly to supply the energy demand and the only remaining fossil fuel available would be coal. although using bio-fuels is possible, their demand for fertile land – required to feed billion people - and the huge quantities involved may limit their use as a major source of energy. . energy demand pattern compounding to supply constraints, the increase in demand aggravates the problem and turns what could be a smooth transition to a more dramatic situation. demand for energy is driven by two main factors – population growth and economic development. the world’s population is estimated to grow from the current . to . billion by , adding . billion people to the planet in just years. this increase is not evenly distributed. the industrialized nations have already stabilized their population at a little over . billion and all the expected population growth should happen in the developing nations (un ). similarly, during this same period the rate of economic development is expected to remain low at less than % in the industrialized countries, while the developing nations should maintain a high - % rate of economic development. the increase in energy demand is expected to remain almost stable in the developed nations, due to a slower economic development balanced by the use of more efficient equipment. contrariwise, consumption should increase at an exponential rate in the developing countries. in spite of an increasing price pattern, the world demand for energy is expected to grow by % from - , with the non-oecd countries accounting for about % of the additional demand. the total energy consumption of the non-oecd countries should surpass the consumption of the oecd countries as early as (eia/ieo ). in the cities of asia, latin america and africa, new businesses are continuously being created, generating employment, and millions of people are swapping their bicycles for cars and acquiring more fridges, tvs, air conditioners and all kinds of home appliances, as personal prosperity rises in line with national economic growth (exxonmobil ). the use of energy is overwhelmingly concentrated in urban areas, where % of the energy consumption takes place, and the urbanization trend remains firm (bp ). until the world’s urban expected to increase dramatically, from . to . billion people. within this context, the cities of the developing nations are expected to double, absorbing . billion new dwellers , and bringing a correspondingly higher demand for housing, infrastructure, jobs and energy (un ). as such, it seems clear that while one focus of attention should be on shifting energy production from fossil fuels to sustainable sources, an equally important one is where the increase in demand will take place: in the rapidly expanding urban centres of the developing nations. the urban population of the less developed regions is expected to increase from , million ( ) to , ( ) – un urbanization prospects, revision database. . urban development alternatives in the developed nations both the urban network and city sizes are almost entirely static. the regional and urban infrastructure is fully developed, limiting the possibility of a significant increase in energy efficiency. because the possibility of physical change is negligible, improvements are limited to increasing the operational efficiency of the transportation network (both inter and intra-urban) and introducing energy conservation strategies. contrariwise, the cities in the developing countries of asia, latin america and africa will double in size in the next forty years to cater for . billion more people. such urban places – equalling in size all the currently existing cities put together - present a unique opportunity to consider the energy factor when planning and building the urban spaces. there are four main areas where urban and regional development planning can contribute to improve energy efficiency and avoid waste: the location of cities, the urban size and land use, and building design. cities are focal points of economic activities - and this is the main single reason why urban centres develop and grow. the basic reasons for development of urban centres are to be found in the economic activities they perform in the economy and the people directly or indirectly employed by these activities. urban location theory is based on the distribution of economic activities throughout the geographic space and in the distribution system (christaller , lösch , alonso , johnson ), taking into account the cost of transportation from the production areas to the consumers. yet the flow of goods that justified the concept of a “central place” hierarchy of urban centres disintegrated in the twentieth century, mostly due to the availability of extremely cheap fuels and the development of modern and efficient means of transportation. rather than based on the typology of the urban economic profile, urban centres with higher product developed faster. economies of scale reinforced the development of primary cities and eventually of mega-cities, with tens of millions inhabitants and attaining economic self-sufficiency regardless of their geographical location. larger cities and metropolises mostly arise because of economies of scale, especially when the availability of human resources and of essential supporting services is essential to compete in the world market. as investments increase, more resources flow in and the more attractive is the city for further investments, which in turn generates employment and attracts migrants. this cycle is especially visible in the developing countries, where such resources are scarce and are frequently limited to a few centres, reinforcing the primacy paradigm. yet the continuous expansion of city sizes does not come without a price – diseconomies of scale such as congestion, failing urban transportation, poor quality of life, pollution, higher land prices and lack of infrastructure – not to mention higher social dysfunctions such as criminality and loss of social order - can erode some of the advantages of the larger centres in favour of alternative locations (royuela & suriñach, ). furthermore, the relative loss of importance of geographic location in urban development may need to be reconsidered as transportation costs increase, restoring some of the original assumptions of the location theory. another issue of larger cities is that their higher affluence level acts as a magnet, generating strong migration flows from smaller centres and urban areas, where employment if limited, income levels are lower and opportunities are scarcer (harris & todaro, ). indeed, the development of urban economic activities often benefits from the labour of migrants. yet while providing mutual economic advantages, excessively fast migration flows tend to overburden urban services and to generate widespread informal settlements and squatters. most local government policies try to alleviate such problems by improving urban conditions: expanding the infrastructure and services networks and incorporating more space to cater for future urban growth. yet such measures may eventually aggravate the problem of excessive urban size and continuous growth. urban energy consumption profiles can vary widely. taking four large asian cities - tokyo, seoul, beijing and shanghai – the amount of energy consumed by industrial activities can range from % in shanghai to only % in tokyo, while residential consumption can vary from % in seoul) to only % in shanghai). beijing consumes only % of its energy in transportation, in contrast with % in tokyo; and while shanghai commercial activities consume % of its energy, tokyo consumes %, ten times as much (doi ). it becomes clear that a range of other factors can influence the energy consumption profile, such as the prevailing economic system and urban affluence, in addition to the level of development and typology of economic activities performed. urban transport is one of the major components in the consumption of energy. it is evident that on average distances increase as the area of the city expands - and longer distances will necessarily consume more energy. furthermore, a road system designed when the city was much smaller and transportation needs more limited cannot cope with the traffic generated when it grows to a size several times larger. enlarging main roads or building elevated highways is sometimes possible, yet at the cost of poorer urban quality. furthermore, as the number of vehicles increases it becomes virtually impossible to expand road sizes at surface level – not mentioning the issue of providing parking spaces. if roads could keep increasing in size according to traffic demands, eventually all the city centre would have to be demolished to make a giant roundabout. to cope with increasing demand for personal transportation, especially the critical home-to-work peak, the favoured solution has been to promote the use of public transport and adopt mass transit solutions, like underground rail systems. yet those systems are expensive to build and operate, and do not provide more than a temporary relief from congestion. eventually there is a point of utter collapse, as some megalopolises have already reached. there is a vast demand for energy ready to explode in the cities of the developing countries. increasing the efficiency of land use design to reduce the demand to travel long distances and stimulating neighbourhood activities and non-motorized traffic (walkways, bicycles, etc) can result in massive savings in energy use. it has been demonstrated that it is possible to have pedestrian cities that can support more than , people without incurring excessive densities, limiting green areas or lowering the quality of live. such settlements do not need to eradicate personal vehicles - the car is also a cherished symbol of freedom besides providing personal comfort. the point is that by making the personal car an option rather than a necessity, it is feasible to have better cities without sacrificing quality of life or the freedom of movement. larger cities could be designed combining such “urban modules”, without significantly changing the concept. cities much larger than one million could be avoided altogether - there are very few economic activities that need a supporting population of over a million people. yet even larger urban conglomerations can be conceived by establishing an urban network, much like the swiss or dutch model. such type of urban structure could provide a concentration of urban dwellers spread throughout a relatively small geographic space, thus providing the benefits of a large concentration of economic activities and resources – taking full advantage of economies of scale without incurring in excessive congestion, pollution, long commuting periods or high transportation costs. such urban development strategy could be adopted in the developing countries, providing not only significant savings in intra-urban transport but also in inter-urban transportation, focusing on a more energy efficient mode such as rail instead of the current tir-based inter-urban transportation network. finally, the building structure can play a significant part in avoiding energy wastage by stimulating environmentally efficient design. except in a few places that have a year-round fair climate – such as brasilia or nairobi – in most cities there is need for heating in the winter or cooling in the summer, and sometimes both. by using the proper building materials, insulation and orientation of openings significant energy savings can be attained without sacrificing comfort. . conclusions it seems clear that we are already facing a major crisis in the supply of energy and that the economic production model based on cheap energy needs to be revised. whatever alternative and sustainable source of energy is preferred, and most probably all means feasibly available will need to be considered, the world economy may have to go through a scarce energy period, in which not only energy will be increasingly expensive, but also difficult to get. to reduce this pressure, not only alternative fuels and other energy sources need to replace current fossil fuels as main sources of energy, but attention should also focus on reducing the growth of demand, by applying technological improvements aiming at higher energy efficiency and through urban development approaches considering the expensive energy situation. urban areas – and particularly those that will be built in the developing countries – will account for most of the additional demand for energy in the next years, absorbing . billion people and almost doubling the demand for energy. those urban centres present a unique opportunity to apply alternative planning approaches considering location, size and land use decisions under a more expensive energy context. similarly, the need to build half a billion new housing units, not including replacements, industrial and commercial buildings - a sizable investment in any count - will also present a major opportunity to implement energy-saving design concepts and building techniques to provide environmental comfort and reduce operational costs. these are unique opportunities because the size of urban population is bound to peak in this century and thus the intensity of urban development expected in this first half of the century is not expected to ever repeat itself. within this context, accessibility should play a decisive role in location decisions: possibly stimulating more concentrated and economically integrated settlements, or avoiding mega cities in favour of more comprehensive system of urban centres. such shift in focus could change dramatically the urban sprawl model, bringing striking repercussions in the real estate market (wsj ). while the market mechanisms will quickly change energy consumption habits and support a shift toward more energy efficient buildings, a massive effort still needs to be made in disseminating such design methods and building techniques, to ensure that the opportunity will not be missed by ignorance. the revision of building codes is a necessary step in this direction although insufficient by itself. on the other hand, urban development decisions on expanding existing cities, building new urban centres and setting up urban infrastructure and services according to a preferred land use pattern – are made by the local, regional or central authorities, who still are not fully aware of their responsibility in participating in the energy management effort. to be sure, there is no new urban development approach – an urban development “recipe” considering the energy issue - that is readily available and just needs to be disseminated. a significant effort in research and development should be made to review the theoretical base of urban development, combining the traditional social, cultural, economic and environmental aspects with the increasing importance of dealing with energy demand issue – a task that should be undertaken primarily by universities, research centres and practitioners in the field. sources and references: alonso, w. location and land use. harvard university press, . british petroleum. “imperial college urban energy project, .” http://www.bp.com christaller, w. central places in southern germany. prentice hall, . deffeyes, kenneth. hubbert’s peak. princeton university press, princeton, nj, . doi, naoko. “urban development and transportation energy demand.” asia pacific research centre, . energy information administration. “international energy outlook – ”. http://www.eia.doe.gov/eia energy information administration. “international energy annual – ”. exxonmobil. “energy outlook”, . http://www.exxonmobil.com harris j. and m. todaro. migration, unemployment & development: a two-sector analysis. american economic review, march . forrester, j. world dynamics. wright allen press, . hopf, james. “world uranium reserves – ”. http://www.americanergyindependence.com hubbert, m. king. “nuclear energy and the fossil fuels.” shell publication # . june . johnson, e.a. the organization of space in developing countries. harvard university press. . karp. j. “cities lure some us residents from afar.” wall street journal, june , pg . lahart, j. “have us drivers reached filling point of no return?” wall street journal, june , pg . lösch, a. the economics of location, yale university press, . meadows et al. the limits of growth, a report to the club of rome. universe books, ; and the limits of growth: the -year update. chelsea green publishing, . muckerheide, j. “how to build , nuclear plants by ”. executive intelligence review, june . http://www.larouchepub.com/other/ / build_ _nukes.html royuela, v. and suriñach. j. “quality of life and urban size”. european regional science association conference papers, . rwe ag – “world energy report – .” http://www.rwe.com safirova, e. et al. “spatial development and energy consumption” (discussion paper). resources for the future, dec . un population division, “world population prospects: the revision and world urbanization prospects”. http://esa.un.org/unpp and http://esa.un.org/unup pnas .. evaluation of intramitochondrial atp levels identifies g /g switch gene as a positive regulator of oxidative phosphorylation hidetaka kiokaa,b, , hisakazu katoa, , makoto fujikawac, osamu tsukamotoa, toshiharu suzukid,e, hiromi imamuraf, atsushi nakanoa,g, shuichiro higoa,b, satoru yamazakih, takashi matsuzakib, kazuaki takafujii, hiroshi asanumaj, masanori asakurag, tetsuo minaminob, yasunori shintania, masasuke yoshidae, hiroyuki nojik, masafumi kitakazeg, issei komurob,l, yoshihiro asanoa,b, , and seiji takashimaa, departments of amedical biochemistry and bcardiovascular medicine and icenter for research education, osaka university graduate school of medicine, osaka - , japan; cdepartment of biochemistry, faculty of pharmaceutical science, tokyo university of science, chiba - , japan; dchemical resources laboratory, tokyo institute of technology, yokohama - , japan; edepartment of molecular bioscience, kyoto sangyo university, kyoto - , japan; fthe hakubi center for advanced research and graduate school of biostudies, kyoto university, kyoto - , japan; departments of gclinical research and development and hcell biology, national cerebral and cardiovascular center research institute, osaka - , japan; jdepartment of cardiovascular science and technology, kyoto prefectural university school of medicine, kyoto - , japan; and kdepartment of applied chemistry, school of engineering and ldepartment of cardiovascular medicine, graduate school of medicine, university of tokyo, tokyo - , japan edited by gottfried schatz, university of basel, reinach, switzerland, and approved november , (received for review october , ) the oxidative phosphorylation (oxphos) system generates most of the atp in respiring cells. atp-depleting conditions, such as hypoxia, trigger responses that promote atp production. how- ever, how oxphos is regulated during hypoxia has yet to be elucidated. in this study, selective measurement of intramitochon- drial atp levels identified the hypoxia-inducible protein g /g switch gene (g s ) as a positive regulator of oxphos. a mitochondria-targeted, fret-based atp biosensor enabled us to assess oxphos activity in living cells. mitochondria-targeted, fret-based atp biosensor and atp production assay in a semi- intact cell system revealed that g s increases mitochondrial atp production. the expression of g s was rapidly and transiently induced by hypoxic stimuli, and g s interacts with oxphos complex v (fof -atp synthase). furthermore, physiological en- hancement of g s expression prevented cells from atp depletion and induced a cellular tolerance for hypoxic stress. these results show that g s positively regulates oxphos activity by interact- ing with fof -atp synthase, which causes an increase in atp pro- duction in response to hypoxic stress and protects cells from a critical energy crisis. these findings contribute to the understand- ing of a unique stress response to energy depletion. additionally, this study shows the importance of assessing intramitochondrial atp levels to evaluate oxphos activity in living cells. energy metabolism | live-cell imaging maintaining cellular homeostasis and activities requires astable energy supply. most eukaryotic cells generate atp as their energy currency mainly through the mitochondrial oxi- dative phosphorylation (oxphos) system. the oxphos sys- tem consists of five large protein complex units (i.e., complexes i–v), comprising more than proteins. in this system, oxygen (o ) is essential as the terminal electron acceptor for complex iv to finally produce the proton-motive force that drives the atp- generating molecular motor complex v (fof -atp synthase). hypoxia causes the depletion of intracellular atp and triggers adaptive cellular responses to help maintain intracellular atp levels and minimize any deleterious effects of energy depletion. although the metabolic switch from mitochondrial respiration to anaerobic glycolysis is widely recognized ( – ), several recent reports have shown that hypoxic stimuli unexpectedly increase oxphos efficiency as well ( – ). in other words, cells have adaptive mechanisms to maintain intracellular atp levels by enhancing oxphos, particularly in the early phase of hypoxia, in which the o supply is limited but still remains. however, the mechanism by which oxphos is regulated during this early hypoxic phase is still not fully understood. revealing the mechanism of this fine-tuned regulation of oxphos requires accurate and noninvasive measurements of oxphos activity. although researchers have established methods to measure oxphos activity, precise measurement, especially in living cells, is still difficult. measuring the intracellular atp concentration is one of the most commonly used methods for evaluating oxphos activity. however, there are two major problems with this method. first, the intracellular atp concen- tration does not always accurately reflect oxphos activity, be- cause it can also be affected by glycolytic atp production, cytosolic atpases, and atp buffering enzymes, such as creatine kinase and adenylate kinase ( ). second, because measurements of the atp concentration by chromatography ( ), ms ( ), nmr ( ), or luciferase assays ( ) are based on cell extract analysis, these methods cannot be used to measure the serial atp concentration changes in living cells in real time. in this study, we overcame these problems by the selective measurement of the intramitochondrial matrix atp concentra- tion ([atp]mito) in living cells. in the final step of oxphos, atp is produced not in the cytosol but in the mitochondrial matrix. therefore, we hypothesized that a selectively measuring [atp]mito is suitable for the highly sensitive evaluation of cellular atp production by oxphos. in fact, real-time evaluation of both [atp]mito and the cytosolic atp concentration ([atp]cyto) in living cells revealed that [atp]mito reflected oxphos activity with far more sensitivity than [atp]cyto. using this fine method, we found that g /g switch gene (g s ), a hypoxia-induced significance we developed a sensitive method to assess the activity of ox- idative phosphorylation in living cells using a fret-based atp biosensor. we then revealed that g /g switch gene , a pro- tein rapidly induced by hypoxia, increases mitochondrial atp production by interacting with fof -atp synthase and protects cells from a critical energy crisis. author contributions: y.a. and s.t. designed research; h. kioka, h. kato, o.t., and a.n. performed research; m.f., t.s., h.i., s.h., s.y., t. matsuzaki, k.t., h.a., m.a., t. minamino, y.s., m.y., h.n., m.k., and i.k. contributed new reagents/analytic tools; h. kioka and h. kato analyzed data; and y.a. and s.t. wrote the paper. the authors declare no conflict of interest. this article is a pnas direct submission. h. kioka and h. kato contributed equally to this work. to whom correspondence may be addressed. e-mail: asano@cardiology.med.osaka-u.ac.jp or takasima@cardiology.med.osaka-u.ac.jp. this article contains supporting information online at www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental. www.pnas.org/cgi/doi/ . /pnas. pnas | january , | vol. | no. | – c el l b io lo g y d o w n lo a d e d a t c a rn e g ie m e llo n u n iv e rs ity o n a p ri l , mailto:asano@cardiology.med.osaka-u.ac.jp mailto:takasima@cardiology.med.osaka-u.ac.jp http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental www.pnas.org/cgi/doi/ . /pnas. protein in cardiomyocytes, increases oxphos activity. g s interacted with fof -atp synthase and increased the atp production rate. our results suggest that hypoxia-induced pro- tein g s is a positive regulator of oxphos and protects cells by preserving atp production, even under hypoxic conditions. results establishment of a sensitive method to assess oxphos activity in living cells. to elucidate the mechanism by which oxphos is regulated under hypoxia, it is essential to establish a sensitive method for assessing oxphos activity in living cells. for this purpose, we used an atp indicator based on e-subunit for an- alytical measurements (ateam), which is an atp-sensing fret-based indicator ( ). we introduced this atp biosensor into cardiomyocytes that possess an abundance of mitochondria and produce the highest levels of atp among all primary cells ( , ). the ateam assay can measure both [atp]cyto (i.e., the cyto-ateam assay) and [atp]mito when a duplex of the mito- chondrial targeting signal of cytochrome c oxidase subunit viii is attached to the indicator (i.e., the mit-ateam assay). in this case, the yfp/cfp emission ratio of the ateam fluorescence represents the atp concentration in each compartment. in- terestingly, the mit-ateam assay was a far more sensitive method than the cyto-ateam assay in determining oxphos activity in living cells. for example, a very low dose of oligomycin a ( . μg/ml), a specific oxphos complex v (fof -atp synthase) inhibitor, greatly reduced the yfp/cfp emission ratio of the mit-ateam fluorescence that represents [atp]mito within min (fig. a, upper and b and movie s ). in contrast, the same dose of oligomycin a resulted in a slight and slow decline of the yfp/cfp emission ratio of cyto-ateam fluorescence (fig. a, lower and b and movie s ). the same phenomenon was observed when the cells were exposed to hypoxia, which suppresses the activity of oxphos complex iv (cytochrome c oxidase). again, [atp]mito decreased more markedly than [atp]cyto during . h of hypoxia (fig. c and d and movie s ). these results indicate that the mit-ateam assay is far more sensitive for measuring the activity of oxphos than the cyto-ateam assay. in addition, oxphos inhibition decreased the yfp/cfp emission ratio of the mit-ateam fluorescence of hela cells as well as cardiomyocytes (fig. s ), suggesting the broad applica- bility of this assay. therefore, we used mit-ateam for the as- sessment of the oxphos activity in living cells. hypoxia-induced gene g s affects the intramitochondrial atp concentration. the expression of genes involved in oxphos regulation is considered to be up-regulated in the early phase of hypoxia. thus, to find unique oxphos regulators, we focused on the rapidly induced genes in response to hypoxic stimulation. we compared the gene expression profiles of cultured rat car- diomyocytes at three different time points during hypoxic con- ditions ( , , and h) (fig. s a). the expression of well-known hypoxia-induced genes, such as vegf-α and hexokinase mrna ( , ), was slightly up-regulated at h and further enhanced at h of hypoxia. in contrast, three other genes (adamts , cdkn , and g s ) underwent rapid increases in expression at h but declined at h of sustained hypoxia (fig. s b and c). this rapid and transient time course of expression implies that these three genes may play distinct regulatory roles, especially in the early hypoxic phase, in which oxygen is limited but still available. to examine whether these genes are involved in the regulation of oxphos activity, we knocked down these genes by shrna (see fig. s a) and examined [atp]mito using the mit-ateam assay. in this experiment, [atp]mito in cardiomyocytes treated with shrna for g s clearly declined within h compared with the control cardiomyocytes (fig. a and movie s ). in addition, the time course of atp decline was in agreement with the time course of g s depletion (fig. a and fig. s a). importantly, the over- expression of g s restored normal atp levels (fig. b and c), and again, the cyto-ateam assay could not detect a significant effect of g s knockdown within this time frame (fig. s b and movie s ). these findings imply that mitochondrial atp pro- duction through oxphos was inhibited by g s ablation. we confirmed that the mrna and protein levels of g s both increased after – h of hypoxia and then declined after h of hypoxia (fig. d and e). g s was first reported as a gene with fig. . establishment of a sensitive method to assess oxphos activity in living cells. (a) yfp/cfp emission ratio plots of (upper) mit-ateam and (lower) cyto- ateam fluorescence in cardiomyocytes. various concentrations ( . , . , . , , and μg/ml) of oligomycin a or dmso (control) were added at min (arrowhead; n = ). (b) representative sequential yfp/cfp ratiometric pseudocolored images of (upper) mit-ateam and (lower) cyto-ateam in car- diomyocytes. oligomycin a ( . μg/ml) was added at min. (scale bars: μm.) (c) yfp/cfp emission ratio plots of mit-ateam and cyto-ateam fluorescence in cardiomyocytes (n = ). (d) representative sequential yfp/cfp ratiometric pseudocolored images of (upper) mit-ateam and (lower) cyto-ateam in cardiomyocytes. cells were exposed to % hypoxia from the time point min. all of the measurements were normalized to the yfp/cfp emission ratio at min. data are represented as the means ± sems. (scale bars: μm.) | www.pnas.org/cgi/doi/ . /pnas. kioka et al. d o w n lo a d e d a t c a rn e g ie m e llo n u n iv e rs ity o n a p ri l , http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/sm .mov http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/sm .mov http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/sm .mov http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/sm .mov http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/sm .mov www.pnas.org/cgi/doi/ . /pnas. expression that was induced during the cell cycle switch from g to g phase ( ). g s is expressed in many tissues and espe- cially abundant in heart, skeletal muscle, liver, kidney, brain, and adipose tissue ( ). although g s may play a role in cell cycle progression ( ), the function of g s in the hypoxic response remains unknown. g s rescues the decline of atp production during hypoxia. we next tested whether the overexpression of the g s before hypoxic stress could prevent hypoxia-induced atp depletion. we prepared cardiomyocytes overexpressing g s and control cardiomyocytes. during sustained hypoxia, [atp]mito gradually declined in control cardiomyocytes as measured by the mit-ateam assay. notably, the overexpression of g s before the onset of hypoxia reduced this decline in [atp]mito, which allowed the cardiomyocytes to promptly recover to baseline levels of [atp]mito after reoxyge- nation (fig. a and b and movie s ). in addition, the prehypoxia overexpression of g s preserved cell viability during sustained hypoxia (fig. c). these results suggest that g s can preserve mitochondrial atp production even under hypoxia and protect cells from the energy crisis under hypoxia. g s binds to fof -atp synthase but not other oxphos protein complexes. to reveal the mechanism by which g s affects [atp]mito, we sought to identify the biochemical targets of g s . we screened for g s binding proteins by immunoaffinity purification of cell lysates from cardiomyocytes expressing c-terminally flag-tagged g s (g s -flag). g s -flag is expressed in cardiomyocytes localized to the mitochondria (fig. s a). ms analysis revealed that multiple fof -atp synthase subunits, but no other mitochondrial respiratory chain complex subunits, were coimmunoprecipitated with g s -flag (fig. s b and table s ). fof -atp synthase is a well-known atp-producing enzyme composed of a protein complex that contains an extramembra- nous f and an intramembranous fo domain linked by a periph- eral and a central stalk ( – ). the binding of fof -atp synthase to g s -flag was confirmed by immunoblotting with anti- bodies against several subunits of fof -atp synthase (fig. a). fig. . g s , a hypoxia-inducible protein, affects intramitochondrial atp concentration in cardiomyo- cytes. (a) sequential yfp/cfp ratiometric pseu- docolored images of mit-ateam fluorescence in cardiomyocytes expressing (upper) shrnas for lacz (shlacz) or (lower) g s (shg s ). oligomycin a ( μg/ml) was added at the end of the time-lapse imaging to completely inhibit atp synthesis. the indicated time represents the period after adenovi- rus infection. (b) representative yfp/cfp ratiometric pseudocolored images of mit-ateam fluorescence in cardiomyocytes expressing the indicated adenovirus for h. (scale bar: a and b, μm.) (c) the bar graph shows the mean yfp/cfp emission ratio of mit-ateam fluorescence in cardiomyocytes express- ing shlacz (n = ), shg s # (n = ), shg s # (n = ), and shg s # + g s wt (n = ) for h. all of the measurements were normalized to the average of the control cells (shlacz). ***p < . . (d) gene expression value plots of g s (red line) and vegf-α (vegfa; black line) levels in cardiomyo- cytes under hypoxic conditions ( % o ). each value was compared with the level of actb expression (n = ). values represent the means ± sems. (e) immu- noblotting of the g s expression in cardiomyocytes under hypoxic conditions ( % o ). fig. . overexpression of g s before hypoxia rescues the decline of mitochondrial atp production during hypoxia. (a) sequential yfp/cfp ratiometric pseudocolored images of mit-ateam fluorescence in cardiomyocytes expressing (upper) g s wt or (lower) lacz during hypoxia and reoxygenation. (scale bar: μm.) (b) yfp/cfp emission ratio plots of mit-ateam fluorescence in cardiomyocytes expressing g s wt (n = ) or lacz (n = ) during hypoxia and reoxygenation. all of the measurements were normalized to the ratio at time and compared between cardiomyocytes with g s wt and lacz at each time point. (c) the bar graph shows the cell viability of cardiomyocytes overexpressing g s under hypoxic conditions. cardiomyocytes expressing either lacz or g s wt were cultured under normoxic or hypoxic conditions for h (n = ). the asterisks denote statistical significance comparing g s with lacz. data are represented as the means ± sems. n.s., not significant. *p < . ; **p < . ; ***p < . . kioka et al. pnas | january , | vol. | no. | c el l b io lo g y d o w n lo a d e d a t c a rn e g ie m e llo n u n iv e rs ity o n a p ri l , http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/sm .mov http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=st conversely, g s -flag was coimmunoprecipitated with fof - atp synthase (fig. s c). g s -flag was also found to be asso- ciated with the fof -atp synthase in t and hela cells (fig. s c). both coimmunoprecipitation using an anti-g s antibody and a reciprocal immunoprecipitation revealed that endogenous g s interacts with fof -atp synthase, whereas none of the proteins in complexes i–iv or adenine nucleotide translocase (ant ; also referred to as adp/atp carrier) were coimmuno- precipitated with g s (fig. b and c). given that the g s protein contains an evolutionarily conserved amino terminus and one hydrophobic domain (hd) ( ), we cre- ated three g s partial deletion mutants to identify the domain in g s that is important for binding to fof -atp synthase (fig. s d). among these mutants, g s Δc and g s Δn but not g s Δhd bound to the fof -atp synthase complex (fig. d and fig. s e and f). furthermore, we confirmed that g s directly inter- acts with fof -atp synthase in an in vitro pull-down assay using a recombinant maltose-binding protein–fused g s protein and purified fof -atp synthase from bovine heart mitochondria (fig. s ). immunocytochemical analysis revealed that endogenous g s colocalized with the β-subunit of fof -atp synthase (fig. e). the knockdown of g s expression by shrna abolished g s staining (figs. s and s a), indicating that both antibodies used for immunostaining specifically recognize g s . these data suggest that g s interacts with the fof -atp synthase complex through its hd in mitochondria and regulates oxphos activity. g s increases mitochondrial atp production rate. [atp]mito is mainly determined by the rate of atp synthesis by fof -atp synthase and atp/adp exchange by the atp/adp translocase ant . this theory means that the increased [atp]mito observed in the g s -overexpressing cells may result from the increased atp synthesis and/or decreased atp/adp exchange, although g s did not interact with ant (fig. b). to resolve this issue and directly measure the rate of atp production in mitochon- dria, we used a semiintact cell system called the mitochondrial activity of streptolysin o permeabilized cells (masc) assay ( ). in this assay, we permeabilized the plasma membrane to wash out any cytosolic components, such as creatine and glycolytic substrates, but left the mitochondria intact. furthermore, we treated the cells with p , p -di(adenosine- ′) pentaphosphate to inhibit the activity of adenylate kinase. these steps allowed us to measure the atp production rate mostly from oxphos, with a minimal contribution of atp buffering systems in the cytosol. the masc assay was suitable for accurate measurement of mi- tochondrial atp production rate, because mitochondria in this semiintact cell system suffered much smaller damage than the isolated mitochondria in the conventional method. surprisingly, in the masc assay, the atp production rate markedly increased when g s was expressed in hela cells that lacked endogenous g s (fig. a). in cardiomyocytes, shrna-mediated g s knockdown decreased the atp production rate in mitochondria, and the expression of g s wt but not g s Δhd could restore the atp production rate (fig. b and fig. s a). in both cells, complete inhibition of atp production by oligomycin a indicated that the observed atp synthesis was catalyzed by oxphos but not other metabolism (fig. a and b). next, to evaluate the physiological role of g s , we examined whether endogenous g s induced by hypoxia could enhance the atp production rate. cardiomyocytes were pretreated with hyp- oxia for h, during which g s expression was largely induced. we then evaluated the atp production rate of both hypoxia- pretreated and nontreated cardiomyocytes under room air con- ditions. even under these equivalent normoxic conditions, hyp- oxia-pretreated cardiomyocytes produced atp faster than nontreated control cardiomyocytes (fig. c and fig. s b). g s knockdown attenuated this increase in the rate of atp produc- tion, indicating that the enhanced atp production rate resulting from hypoxia pretreatment primarily depends on endogenous g s induction. this increased g s expression was essential for cell survival, because g s -depleted cells died earlier than control cells under conditions of hypoxic stress (fig. d) furthermore, to assess the effect of g s on cellular respiration, we continuously measured the oxygen consumption rate (ocr) using an xf extracellular flux analyzer. g s knockdown de- creased the basal ocr of cardiomyocytes, most likely because of the decreased activity of atp synthesis (fig. e and f). in con- trast, the proton leakage of the mitochondrial inner membrane and the maximum respiratory capacity of oxphos complexes i–iv were unaffected by g s ablation (fig. e and f). these data show that g s knockdown reduced respiration caused by atp synthesis without affecting respiration caused by proton leakage, nonmitochondrial respiration, or the maximal respira- tion capacity. all these findings indicate that g s enhances the mitochondrial atp production rate by increasing the activity of fof -atp synthase. discussion in this study, we showed that g s kinetically increased oxphos activity through direct binding to fof -atp synthase. our previous fig. . g s interacts with the fof -atp synthase in mitochondria. (a) im- munoprecipitation (ip) of g s -flag in cardiomyocytes. cell lysates from cardiomyocytes expressing g s -flag or lacz were immunoprecipitated with an anti-flag antibody. (b) ip of endogenous g s in cardiomyocytes. en- dogenous g s was induced by hypoxia and immunoprecipitated using an anti-g s antibody. c, oxphos complex; fof , fof -atp synthase. *igg light chain. (c) ip of fof -atp synthase in cardiomyocytes under normoxic or hypoxic conditions. cell lysates from cardiomyocytes cultured under nor- moxia or hypoxia for h were immunoprecipitated with an antibody against the whole fof -atp synthase complex or a control igg. *nonspecific band. (d) ip of g s mutants expressed in cardiomyocytes. cell lysates were immu- noprecipitated with an anti-flag antibody. (e) immunostained images of hypoxia-stimulated ( h) cardiomyocytes with anti-g s (green) and anti–fof - atp synthase β-subunit (red) antibodies. (scale bars: μm.) | www.pnas.org/cgi/doi/ . /pnas. kioka et al. d o w n lo a d e d a t c a rn e g ie m e llo n u n iv e rs ity o n a p ri l , http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf www.pnas.org/cgi/doi/ . /pnas. studies of fof -atp synthase have revealed that this enzyme has a specific structure that connects two molecular nanomotors that synchronize with each other to produce atp ( – ). these physically distinct structures suggest that a specific activating fac- tor for fof -atp synthase must exist. combined with the find- ings from this study, we hypothesize that g s may lower the activation barrier of the fof -atp synthase nanomotor and enhance the atp production rate with the equivalent proton motive driving force (pmf; i.e., the sum of the membrane po- tential and the ph gradient). activation barriers might be gen- erated by various factors, such as friction between the stator and rotor of fof -atp synthase, physical and electrical resistance to proton transport through the channel, and the existence of ro- tary blockers such as the bacterial e-subunit and cyclophilin d ( ). the increased atp production rate caused by g s over- expression observed in the masc assay supports this hypothesis, because the pmf in the initial phase of this assay should be the same. if this hypothesis is true, even with reduced pmf, cells that express g s should produce atp faster than cells that express little or no g s . in fact, g s overexpression attenuated the de- cline of [atp]mito under hypoxic conditions that reduced the pmf. precise real-time measurement of the pmf is currently difficult, but these hypotheses might be proven in future studies. kinetically faster atp production should accompany greater consumption of both o and pmf; however, our results suggest that preserving atp production is more beneficial than preserving pmf for cell viability, particularly when the o supply is restricted but still exists. the transience of endogenous g s expression induced by hypoxia might serve to protect tissues in the early phase of energy crisis. there may be specific mechanisms to decrease g s expression under prolonged ischemia that have yet to be identified. another possible mechanism by which g s could increase the atp pro- duction rate is that g s increases the fo-f coupling efficiency of fof -atp synthase. however, this hypothesis is less likely, because g s altered the oxygen consumption rate to increase the atp production rate. although this uncoupling phenomenon has rarely been reported for mammalian mitochondrial fof -atp synthase, we cannot completely eliminate the possibility that intrinsically fig. . g s enhances the mitochondrial atp production rate. (a and b) masc assay of (a) permeabilized hela cells expressing the indicated plasmids or (b) car- diomyocytes expressing the indicated adenovirus in the presence (dotted lines) or absence (solid lines) of μg/ml oligomycin a (oli a). upper shows the atp pro- duction plots, and lower shows the mean atp production rates between and min. (a) n = . (b) solid lines, n = ; dotted lines, n = . (c) masc assay of permeabilized cardiomyocytes pretreated with hypoxia. cells expressing the indicated adenovirus were pretreated with or without hypoxia for h. after the pre- treatment, the cells were permeabilized under room air conditions followed by masc assay in the presence (dotted lines; n = ) or absence (solid lines; n = ) of μg/ ml oli a. upper shows the atp production plot, and lower shows the mean atp production rate between and min. (d) the bar graph represents the cell viability of g s -depleted cardiomyocytes under hypoxic conditions. cardiomyocytes expressing shlacz or shg s (# ) were cultured under normoxic or hypoxic conditions for h. (e and f) the ocr in cardiomyocytes expressing shlacz and shg s (# ) under basal conditions and in response to the indicated mitochondrial inhibitors (n = ). fccp, carbonyl cyanide- -(trifluoromethoxy)-phenylhydrazone. data are represented as the means ± sems. n.s., not significant. **p < . ; ***p < . . kioka et al. pnas | january , | vol. | no. | c el l b io lo g y d o w n lo a d e d a t c a rn e g ie m e llo n u n iv e rs ity o n a p ri l , uncoupled fof -atp synthase exists, because we could not ac- curately measure the amount of uncoupled fof -atp synthase in intact cells. g s was first identified in cultured monocytes during the drug-induced cell cycle transition from g to g phase ( , ). a limited number of studies have implied that g s is involved in cell proliferation ( ), differentiation ( ), apoptosis ( ), inflammation ( ), and lipid metabolism ( ) in various cellular settings. moreover, g s was reported to localize to the cytosol ( ), endoplasmic reticulum ( ), mitochondria ( ), or the surface of lipid droplets ( ). how g s distinguishes these multiple functions is still not clear. in our hands, g s is always localized to mitochondria, which was shown by immunostaining with two antibodies against different epitopes of g s (fig. s ). complete depletion of mitochondrial staining by g s knockdown strongly suggests the specific localization of g s to mitochondria. we also showed that g s specifically bound to mitochondrial fof -atp synthase but not other oxphos protein complexes and functionally regulated oxphos activity. together, these data suggest that g s acts in the mitochondria. however, different cellular conditions may change the localiza- tion and role of g s . additionally, g s -mediated changes in atp metabolism may possibly affect the lipid metabolism or cellular proliferation. additional studies will reveal the functional mechanisms by which g s exerts these multiple functions in different cellular conditions. in this study, we evaluated [atp]mito and [atp]cyto separately using fret-based atp biosensors in living cells. this dual evaluation revealed that [atp]mito reflected mitochondrial atp production with much greater sensitivity than [atp]cyto (fig. and movies s and s ). because [atp]cyto is strongly influenced by the activity of various cytosolic atp hydrolytic enzymes and atp buffering enzymes, [atp]cyto does not always reflect the atp availability that determines cellular function. taken together, our results indicate that g s is a positive regulator of oxphos that works to increase the mitochondrial atp production rate even under hypoxic conditions. therefore, enhancing the level and function of g s could be beneficial for hypoxia- and mitochondria-related disorders, such as ischemic diseases, metabolic diseases, and cancer. materials and methods cells were infected with adenovirus encoding fret-based atp indicators at . or mit-at . to measure changes in cytosolic or mitochondrial atp concen- trations, respectively. image acquisitions and fret analyses were performed as described previously with some modifications ( ). for the control of oxygen concentration during time-lapse imaging, digital gas mixer for stage-top in- cubator gm (tokai hit) was used to create hypoxic ( % o ) or normoxic ( % o ) condition. additional methods are found in si materials and methods. acknowledgments. we thank m. murata for helpful discussions and advice, h. miyagi (olympus co. ltd.) for technical advice regarding mi- croscopy, t. miyazaki (cyclex co. ltd.) for making antibodies, s. ikezawa and a. ogai for technical assistance, k. tanaka for help with the purification of bovine fof -atp synthase, and y. okada and h. fujii for secretarial support. this research was supported by the japan society for the promotion of science through the funding program for next generation world-leading researchers (next program) initiated by the council for science and technology policy; grants-in-aid from the ministry of health, labor, and welfare–japan; and grants-in-aid from the ministry of education, culture, sports, science, and technology–japan. this research was also supported by grants from takeda science foundation, japan heart foundation, japan cardiovascular research foundation, japan intractable diseases research foundation, japan founda- tion of applied enzymology, japan medical association, uehara memorial foundation, mochida memorial foundation, banyu foundation, naito foun- dation, inoue foundation for science, osaka medical research foundation for intractable diseases, ichiro kanehara foundation, and showa houkoukai. . kim jw, tchernyshyov i, semenza gl, dang cv ( ) hif- -mediated expression of pyruvate dehydrogenase kinase: a metabolic switch required for cellular adaptation to hypoxia. cell metab ( ): – . . papandreou i, cairns ra, fontana l, lim al, denko nc ( ) hif- mediates adaptation to hypoxia by actively downregulating mitochondrial oxygen consumption. cell metab ( ): – . . semenza gl ( ) hypoxia-inducible factors in physiology and medicine. cell ( ): – . . semenza gl, et al. 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( ) the g( )/g( ) switch gene regulates adipose lipolysis through association with adipose triglyceride lipase. cell metab ( ): – . | www.pnas.org/cgi/doi/ . /pnas. kioka et al. d o w n lo a d e d a t c a rn e g ie m e llo n u n iv e rs ity o n a p ri l , http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=sf http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/sm .mov http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/sm .mov http://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental/pnas. si.pdf?targetid=nameddest=stxt www.pnas.org/cgi/doi/ . /pnas. microsoft word - cst - - revised - accepted - final © applied science innovations pvt. ltd., india carbon – sci. tech. / ( ) - research article received: / / , accepted: / / ------------------------------------------------------------------------------------------------------------------------- estimation of the monthly average global and diffuse solar radiation for the city bareilly, uttar pradesh, india akanksha varshney, k. namrata, and bhushan mahajan department of electrical engineering, national institute of technology, jamshedpur, india. abstract: this paper presents a process to develop the monthly global and diffused solar radiation data for the city bareilly, uttar pradesh in order to exploit the solar energy available at the location throughout the year. it is located in the northern zone of uttar pradesh at . °n latitude and . °e longitude at an elevation of meters. the values of monthly average global solar radiation are calculated using the regression constants in the model provided by gopinathan. kreith and gupta model has been used for estimating the values of monthly average diffuse solar radiation. the calculated data has been analyzed and the result has been simulated through matlab. keywords: solar constant, solar day length, bareilly, uttar pradesh ------------------------------------------------------------------------------------------------------------------------------------- . introduction: solar energy is a very large, inexhaustible and environmentally clean source of energy. it is sufficient to meet all the present and future energy demands of the world [ ]. a number of technologies have been developed to harness its potential. solar radiation data provides information of how much the sun's energy strikes the surface at a place on earth during a particular period [ ]. such data is available for most of the developed countries of the world. india, being a tropical country receives adequate amount of sunshine for most of the time of the year but the parameters are measured only in a few meteorological stations. hence to recognize its true potential, data should be available for each and every corner of the country. for places where it is not directly measured, solar radiation data can be estimated by using models and empirical correlation [ ]. presently, global solar radiation in india is measured at four work stations namely delhi, kolkata, mumbai and chennai [ - ].bareilly is the eighth largest metropolis in uttar pradesh and the thlargest city in india. it occupies an area of sq km and receives good amount of sunshine throughout the year [ - ]. solar radiation estimation can unlock the potential of solar energy making it a viable option for developing energy for this place. . methodology: the angstrom correlation has served as a basic approach to estimate global radiation for a long time. he was the first to relate the amount of sunshine received at a place, by a linear relation given as [ - ] – = 𝑎 + 𝑏 ̅ ̅ ( ) where 𝐻 is the monthly average daily global solar radiation received on a horizontal surface (mjm- day- ), 𝐻 is the monthly average daily extraterrestrial radiation on a horizontal surface (mjm- day- ), a and b are regression constants, s is the monthly average daily number of hours of bright sunshine, 𝑆̅ is the monthly average daily maximum number of hours of possible sunshine. the value of 𝐻 is calculated as: 𝐻 = 𝐼 ( + . 𝑐𝑜𝑠 )(⍵ 𝑠𝑖𝑛𝜑 𝑠𝑖𝑛𝛿 + 𝑐𝑜𝑠𝜑 𝑐𝑜𝑠𝛿 𝑠𝑖𝑛𝜔 ) ( ) asi carbon – science and technology issn – http://www.applied-science-innovations.com © applied science innovations pvt. ltd., india carbon – sci. tech. / ( ) - where isc is the solar constant having value of w/m , n is the average number of days in a month, φ is the latitude of the location, δ is the declination angle calculatedas: 𝛿 = . sin ( ) ( ) and ωs is the sunset hour angle given as: 𝜔 = cos (−𝑡𝑎𝑛𝛿 𝑡𝑎𝑛𝜑) ( ) considering the value of ωs in degree, the value of 𝑆 is calculated as 𝑆̅ = ( ) gopinathan considered the effects of latitude, elevation and established the following equation to calculate regression coefficients a and b of the angstrom type correlation for global radiation [ ] 𝑎 = − . + . cos 𝜑 − . ℎ + . ̅ ̅ ( ) 𝑏 = . − . cos 𝜑 + . ℎ − . ( ̅ ̅ ) ( ) where h is the elevation of the place. usually (a+b) has values in the range of . for a moist and turbid atmosphere and . for a dry and dust free atmosphere [ - ]. the diffuse radiation 𝐻 can be estimated by an empirical formula illustrated in equation ( ) which correlates the diffuse solar radiation component 𝐻 to the global solar radiation 𝐻 . this linear expression was obtained when the available indian data was analyzed [ ]. = . − . [ ] ( ) the ratio 𝐻 𝐻⁄ is denoted by 𝐾 and is called the monthly average clearness index [ ]. this parameter indicates the degree of clearness of the atmosphere. . results and discussion: the monthly average global solar radiation for the city bareilly has been calculated by the above provided gopinathan model while kreith and gupta model has been used for estimation of diffuse radiation. table shows the calculated values of input parameters for estimation of both global and diffuse radiation. table ( ): calculated values of input parameters for the city bareilly. month n (starting from st anuary) δ (in degrees) ωs (in radians) january - . . february - . . march - . . april . . may . . june . . july . . august . . september . . october - . . november - . . december - . . © applied science innovations pvt. ltd., india carbon – sci. tech. / ( ) - table ( ) depicts the values of monthly average daily number of hours of bright sunshine (𝑆̅), monthly average daily maximum number of hours of possible sunshine (𝑆̅ .) and monthly average daily extraterrestrial radiation (𝐻 ). the regression constant values vary all over the year due to the variation in possible sunshine hour ratio. the approximate values ofa andb for bareilly can be obtained as . and . respectively. table ( ): values of regression coefficient and clearness index for bareilly, uttar pradesh. month (in hour) (in hour) (mj/m -day) january . . . february . . . march . . . april . . . may . . . june . . . july . . . august . . . september . . . october . . . november . . . december . . . in table ( ), the values calculated for monthly global solar radiation ( ), diffuse solar radiation ( ) and clearness index ( ) have been shown. table ( ): complete solar radiation data for bareilly, uttar pradesh, india month (mj/m -day) (mj/m -day) january . . . february . . . march . . . april . . . may . . . june . . . july . . . august . . . september . . . october . . . november . . . december . . . in figure ( , and ), the values calculated for , and , have been plotted respectively, after simulation through matlab. © applied science innovations pvt. ltd., india carbon – sci. tech. / ( ) - figure ( ): monthly variation of global solar radiation for bareilly. figure ( ): monthly variation of diffuse solar radiation for bareilly. © applied science innovations pvt. ltd., india carbon – sci. tech. / ( ) - figure ( ): monthly variation of clearness index for bareilly. . conclusions: results have shown that the maximum and minimum values of global solar radiation are obtained in the month of may and december respectively. the maximum and minimum values of diffuse solar radiation are obtained in the month of july and november respectively. the sky over bareilly is clear for most of the months except for july and august, when the clearness index is less than %. hence, may is the most appropriate month for using solar energy in bareilly city as it receives the maximum amount of solar radiation in this month. the data that has been calculated through this work may play vital role in solving the energy crisis problem in bareilly by the solar energy conversion process. references: . s. p. sukhatme, energy principles of thermal collection and storage, nd edition, , tata mcgraw-hill, new delhi, india. . b. y. h. liu&r. c. jordan, ‘the interrelationship and characteristic distribution of direct diffuse and total solar radiation’, solar energy / ( ) - . . k. namrata, s. p. sharma,s. b. saksena, ‘comparison of different models for estimation of global solar radiation in jharkhand (india) region’, smart grid and renewable energy ( ) - . . a. k. rajput, r. k. tiwari,a. sharma, ‘utility based estimated solar radiation at destination pune in maharashtra (india)’, int. j. pure appl. sci. technol. ( ) - . . a. k. rajput, d. v. avasthi,d. kumar, ‘variation of estimated insolation from east to west in uttar pradesh (india)’, cipeh( ) - . . http://www.censusindia.gov.in/ census/dchb/ _part_b_dchb_bareilly . https://www.weather visit.com/asia/india/bareilly-december.htm . a. angstrom,‘solar and terrestrial radiation’, quarter jourtnal of royal meteorological society ( ) - . . j. a. duffieand w. a. beckman, solar engineering of thermal processes, nd edition, , new york: john wiley & sons inc. © applied science innovations pvt. ltd., india carbon – sci. tech. / ( ) - . k. k. gopinathan, ‘a new model for estimating total solar radiation’, solar and wind technology ( ) - . . a. mani and s. rangarajan, solar radiation over india, , allied publishers, new delhi, india. . s. s.chandel, r. k. aggarwal, anda. n. pandey, ‘new correlation to estimate global solar radiation on horizontal surfaces using sunshine hour and temperature data for indian sites’, asme ( ) - . . v. modiands. p. sukhatme,‘estimation of daily, total and diffuse insolation in india from weather data’, solar energy ( ) . . f. kreith and j. f. kreider, principles of solar engineering, , mcgraw-hill, new york. author’s biography: akanksha varshney has graduated in electrical engineering from rajkiya engineering college, banda in uttar pradesh in the year . currently she is pursuing her master's degree in power system engineering from national institute of technology, jamshedpur in jharkhand. her research interests are in the field of power system and renewable energy systems. k. namrata holds a degree in renewable energy technologies in which her research topic was based on solar radiation and its effect solar power generation technology. currently she is an assistant professor in the department of electrical and electronics engineering at n.i.t. jamshedpur, india. bhushan mahajan received b. tech (electrical engineering) degree from dr. babasaheb ambedkar technological university, maharashtra, india in . currently, he is pursuing his m. tech (power electronics and drives) from nit jamshedpur, india. his main research interests are power electronics, renewable energy systems and smart grids. ***** microsoft word - -p -no. editorial j. cent. south univ. ( ) : − doi: https://doi.org/ . /s - - - preface to the special issue on energy utilization and conservation liao sheng-ming(廖胜明) , sun zhi-qiang(孙志强) , zhou chenn(周谦) . school of energy science and engineering, central south university, changsha , china; . center for innovation through visualization and simulation, purdue university northwest, hammond, in , usa © central south university press and springer-verlag gmbh germany, part of springer nature energy utilization and conservation are seen as important solutions to energy crisis and environmental pollution. new technologies, such as renewable energy utilization, high-efficiency conversion, energy management, and energy saving, are playing important roles in industry. however, improving performance and reducing costs in their implementation are still big challenges and therefore going to be hot topics. in recent years, significant research progresses on these topics have been made from fundamental studies to application- oriented prototypes around the world. we organize this special issue “energy utilization and conservation” in journal of central south university to show the latest advances. this special issue includes twenty-three original contributions. the topics cover theoretical study and application of multiphase flow. flow characteristics at low reynolds number around two in-line circular cylinders with slits was investigated by sun zhi-qiang and his group; song yan-po et al reconstructed bubble profiles from gas−liquid two-phase flow data. moreover, a propagation based thermal conductivity measurement method was developed by zhou tian et al. we also thank to the authors’ contributions in entropy analysis of flow statement in porous medium, and natural convection horizontal annular finned tube. six articles about energy system engineering and renewable energy are also included in this special issue. liao sheng-ming and his group built an energy prediction model for urban energy consumption. ma wei-wu et al evaluated and compared working fluids for organic rankine cycles (orcs) by developing group-contribution methods and second-law-based models. also, liu li et al numerically studied the geothermal heat extracted by fluid flowing in buried tube and yin et al experimentally studied the repair characteristics of damaged rock salt of underground gas storage. two articles focusing on combustion are also included. fan ai-wu and his group examined the effects of wall thickness and materials on flame stability in a planar micro-combustor. as well, catalytic combustion characteristic of hydrogen/air in the micro turbine engine was analyzed by e jia-qiang et al. in addition, several articles on heat and mass transfer in smelting, electrolysis and welding are also presented. in summary, these contributions present the cutting-edge researches in the field of energy utilization and conservation. we would like to sincerely thank all the authors for their great efforts in preparing high-quality manuscripts. we also thank the professional editorial office of journal of central south university for their hard-works to make this issue such a great success. guest editors liao sheng-ming prof. liao obtained his b.s. and m.s. from tsinghua university in and , respectively, and phd from hong kong university of science and technology in . since , he has been a professor in the school of energy science and engineering, central south university (csu), china. his current research interests are focused on j. cent. south univ. ( ) : − energy system engineering, new energy, energy saving technologies, and basic problems of thermal physics and energy utilization in engineering. as one of the earliest scholars to study trans-critical co refrigeration and heat pump cycles in china, he has published over refereed papers with him as the first or corresponding author, including energy, energy conversion and management applied thermal engineering, international journal of heat and mass transfer, asme journal of heat transfer, progress in computational fluid dynamics, and the relevant research papers in these international academic journals have been widely cited and reviewed by international peers. sun zhi-qiang prof. sun is with school of energy science and engineering, central south university, china, and currently he is the dean of the school. prof. sun obtained his b.s. and m.s. from central south university in and , respectively, and he earned his phd from zhejiang university in . during − he worked as a visiting scholar at duke university, usa. his major research areas include theory and measurement techniques for multiphase flow, thermal design and heat transfer optimization, and new energy technologies. he is the author or co-author of four books and has published more than peer-reviewed papers. prof. sun is granted the new century talents and young talents of hunan province, china. zhou chenn prof. zhou obtained her b.s. and m.s. from nanjing university of aeronautics and astronautics in and , respectively, and phd from carnegie mellon university in . she jointed purdue university northwest in and became full professor in . since , she has been a professor by courtesy in the school of mechanical engineering, purdue university west lafayette, usa. her current research interests are focusing on innovation through visualization and simulation. in recent years, she has published copyrighted software, patents and more than papers on technical journals, magazines, and conference proceedings. she had been an asme fellow since . liao sheng-ming (phd, professor; tel: + - - ; e-mail: smliao@csu.edu.cn) sun zhi-qiang (phd, professor; tel: + - - ; e-mail: zqsun@csu. edu.cn; web of science researcher id: s- - ) zhou chenn (phd, professor; tel: + - - - ; e-mail: czhou@pnw. edu) energies article a stochastic approach to energy policy and management: a case study of the pakistan energy crisis zaman sajid ,* and asma javaid department of process engineering, faculty of engineering and applied science, memorial university of newfoundland, st. john’s, nl a b x , canada department of computer science, memorial university of newfoundland, st. john’s, nl a b x , canada; ajavaid@mun.ca * correspondence: zaman.sajid@mun.ca; tel.: + - - - received: august ; accepted: september ; published: september ���������� ������� abstract: the energy policy of a country dictates its ability to better manage and deal with an energy crisis. a sustainable energy policy deals with not only energy production but also with energy consumption. in the past, the government of pakistan has lacked such an approach. this study aims to develop a policy-making framework to improve the energy management of pakistan through a probabilistic approach. stochastic analysis is performed in this study and the uncertainty in energy data is used to propose a holistic energy policy. energy-utilization data from different sources are used to compare the accuracy of energy-consumption data from to . the analysis reveals that there exists an uncertainty in energy-consumption data and the major cause of this uncertainty is energy theft. the analysis shows that the industry has the highest uncertainty in its energy-data utilization, followed by the transport and the domestic sectors of pakistan. based on stochastic analysis, seven recommended energy-policy guidelines are presented to manage the energy crisis in the country. the analysis proposes that pakistan needs to take measures to control energy theft. keywords: energy; policy; theft; uncertainty; loss; guidelines . introduction pakistan, being the world’s sixth largest populated country, has quite obvious energy demands [ ]. an analysis of pakistan’s historical energy consumption and supply data, as represented in the literature [ ], shows an increasing trend in both variables. such trends are quite obvious as pakistan’s population has increased tremendously over time; its growth rate has been . percent per annum [ ]. this increase in population positions pakistan as an overpopulated country with respect to its energy resources being explored or used. to meet its energy demands, pakistan is largely dependent on conventional energy sources such as coal, natural gas, and petroleum. to fulfil energy demands, % of the total energy in pakistan is fulfilled through conventional energy sources [ ]. electricity in pakistan is produced mainly through these energy sources. in , nearly , gwh of electricity was produced in pakistan. in the energy mix of the country, the contributions of thermal, hydel, and nuclear power are . %, . %, and . %, respectively [ ]. in thermal power, petroleum oil makes the highest contributions with . %, while natural gas and coal make up . % and . %, respectively [ ]. pakistan, located at an excellent topological location and blessed with natural hydrological conditions, has huge potential for hydropower, which can add huge amounts of energy in pakistan’s energy portfolio. there is a potential for nearly , mw of energy that can be produced from hydropower in the country, most of which lie in khyber pakhtunkhwa, azad jammu and kashmir, punjab, and gilgit-baltistan [ ]. the distribution of hydropower generation for each province is shown in figure . energies , , ; doi: . /en www.mdpi.com/journal/energies http://www.mdpi.com/journal/energies http://www.mdpi.com https://orcid.org/ - - - http://dx.doi.org/ . /en http://www.mdpi.com/journal/energies http://www.mdpi.com/ - / / / ?type=check_update&version= energies , , of energies , , x for peer review of and kashmir, punjab, and gilgit-baltistan [ ]. the distribution of hydropower generation for each province is shown in figure . figure . pakistan’s hydropower potential (pakistan’s map courtesy of ontheworldmap.com). hydropower resources are mainly located in the northern region of pakistan. as shown in figure , these resources can be divided into six regions, namely, punjab, khyber pakhtunkhwa, gilgit-baltistan, sindh, azad jammu and kashmir, and balochistan. in the khyber pakhtunkhwa region, there are nearly hydropower project sites and these projects have a total hydropower potential of , mw. out of this, projects producing mw of energy are in operation and projects producing mw and mw are in the implementation phase by the public and private sector, respectively. while feasibility studies of mw projects have been completed and mw of hydropower projects are raw sites (sites identified but no technical feasibility conducted) in khyber pakhtunkhwa—all totaling to , mw. in gilgit-baltistan, there is total potential of , mw of hydropower energy, out of which mw of projects are raw sites while feasibility studies of mw of hydropower projects have been completed. both the public sector and private sector are implementing hydropower projects worth , mw and mw in gilgit-baltistan, while operational projects are producing mw of energy. the punjab province of pakistan has potential to produce mw of hydropower, out of which operational projects are producing mw of energy, while projects in pipelines can produce mw and mw of hydropower through public- and private-sector investments, respectively. in punjab, a feasibility study has been completed for projects worth mw of energy and raw-site projects have potential to produce mw of hydropower energy in the province. hydropower resources in azad jammu and kashmir play an important role and have an energy potential of mw, in which operational projects are producing mw of hydropower, while the projects under the implementation phase would produce mw and mw of power through the public and private sectors, respectively. in azad jammu and kashmir, there are mw of hydropower projects with raw sites, while mw project feasibility has been completed. there are no hydropower projects, either operational or implemented, in sindh and balochistan. in sindh and balochistan, a feasibility study has been completed for projects to figure . pakistan’s hydropower potential (pakistan’s map courtesy of ontheworldmap.com). hydropower resources are mainly located in the northern region of pakistan. as shown in figure , these resources can be divided into six regions, namely, punjab, khyber pakhtunkhwa, gilgit-baltistan, sindh, azad jammu and kashmir, and balochistan. in the khyber pakhtunkhwa region, there are nearly hydropower project sites and these projects have a total hydropower potential of , mw. out of this, projects producing mw of energy are in operation and projects producing mw and mw are in the implementation phase by the public and private sector, respectively. while feasibility studies of mw projects have been completed and mw of hydropower projects are raw sites (sites identified but no technical feasibility conducted) in khyber pakhtunkhwa—all totaling to , mw. in gilgit-baltistan, there is total potential of , mw of hydropower energy, out of which mw of projects are raw sites while feasibility studies of mw of hydropower projects have been completed. both the public sector and private sector are implementing hydropower projects worth , mw and mw in gilgit-baltistan, while operational projects are producing mw of energy. the punjab province of pakistan has potential to produce mw of hydropower, out of which operational projects are producing mw of energy, while projects in pipelines can produce mw and mw of hydropower through public- and private-sector investments, respectively. in punjab, a feasibility study has been completed for projects worth mw of energy and raw-site projects have potential to produce mw of hydropower energy in the province. hydropower resources in azad jammu and kashmir play an important role and have an energy potential of mw, in which operational projects are producing mw of hydropower, while the projects under the implementation phase would produce mw and mw of power through the public and private sectors, respectively. in azad jammu and kashmir, there are mw of hydropower projects with raw sites, while mw project feasibility has been completed. there are no hydropower projects, either operational or implemented, in sindh and balochistan. in sindh and balochistan, a feasibility study has been completed for projects to produce mw and mw of hydropower, respectively. sindh province has identified raw sites that can produce hydropower of mw, but there has been no raw site identified in balochistan [ ]. energies , , of despite all these and various other potential energy resources, today pakistan is facing a huge energy crisis. there are many factors which precipitated this severe energy crisis. these is a rapid increase in demand for energy in the manufacturing sector [ , ], the transportation sector, which includes transportation by road vehicles, rail, aviation, and shipping [ ], industrial-sector growth [ ], a slow uptake in adopting new renewable-energy technologies and ineffective energy policies [ ], and the sluggishness in exploring more natural energy resources like coal, natural gas, and crude oil [ ]. moreover, hikes in energy prices and the poor development of energy-management policies have played a vital role in darkening the streets of pakistan [ ]. in the electricity sector alone, there is approximately a gap of – mw between the demand and production of electricity, which is increasing at a steady rate of %– % on an annual basis [ ]. though such facts are either presented by government of pakistan [ ] or by researchers, there exists an uncertainty within these data that has misled policy makers in the past. uncertainty in data is defined as the deviation of the data from their original values or the lack of true data [ ]. analytically speaking, due to the presence of uncertainty in data, a mathematical model may not be an accurate representation of the system, but only an approximate one. uncertainty in data is related to the level of precision of the data. in probabilistic terms, it would be the probability of the correctness of the value of the data and these data characteristics need to be estimated and reported along with the data presented. there are two methods to quantify uncertainties in a system: deterministic and stochastic. in the deterministic method, all properties of a system are well-known and there is no randomness present in any system variable. the outcomes of deterministic mathematical models can be precisely determined. in these models, the same output will always be produced every time a given input is used. on the other hand, the stochastic method includes randomness in the model, which means that, with the assumptions of initial conditions (range of values), there are different outcomes or ranges of values. these assumptions and outcomes are represented in terms of probability distributions. one type of stochastic method is the monte carlo method. the monte carlo method repeatedly simulates the behavior of a physical system. the process is known as a monte carlo simulation (mcs). the basic principle behind mcs is that of stochastic uncertainty propagation [ ]. in an uncertainty analysis, a monte carlo simulation produces outputs in terms of probability distributions while considering the randomly varying uncertainties in the inputs, which are based on defined probability distributions [ ]. uncertainty is determined by analyzing the distribution of the simulated outputs. this characteristic allows the accommodation of nonlinear relationships among different uncertainties, since summing various uncertainties does not result in the final uncertainty [ ]. in mcs, the input quantities are assigned with known probability density functions (pdfs). such assigned distributions are propagated through the model, which represents the mathematical relationship among input and output quantities, to develop a pdf of the output. the knowledge of pdfs for input parameters is the key to evaluate the behavior of unknown random outputs [ ]. a pdf of a quantity is its probabilistic profile by which the quantity is observed in a random measurement process [ ]. the stochastic model, which represents the inputs and outputs, is: y = f(x , x , x , . . . xn) ( ) where y is the output quantity, also known as “measurand”, and x , x , x . . . xn are sets of n number of input quantities. the f in equation ( ) shows the measurement formula through which inputs are passed along to produce outputs. there are various types of pdfs that could be assigned to the input variables, the details of which are presented in the literature [ ]. since the objective is to perform the simulations many times to replicate the actual system, a computer-based mcs allows many simulations ( , trials or more). the use of random inputs turns the deterministic model into a stochastic one. previously, many researchers have studied uncertainty in various aspects. an uncertainty present in data influences the quality of decision-making processes; therefore, such ambiguities cannot be ignored. previously, there have been many studies performed on data uncertainties for a wide range of subjects. a study was conducted to accurately model the market operator based energies , , of on transactive energy by considering uncertainty in network interaction and inputs [ ]. in this study, the taguchi orthogonal array test (toat) unit was used to generate uncertainty scenarios with occurrence probability. researchers also modeled uncertainties in load and wind turbines using normal distributions and weibull distributions, respectively. the study provided optimal control of energy-system resources and demand-side management [ ]. in another study, a smart transactive energy framework was presented that studied energy-demand fluctuations management. the study developed demand-side management based on total profit considering the uncertainty [ ]. stochastic modeling has been a powerful tool in the past to study uncertainty in data. for example, stochastic modeling was utilized to study uncertainty in energy-management schemes by incorporating conditional value at risk (cvar) [ ]. in another study, stochastic approach was used to study economic performance of renewable energy systems [ ]. uncertainty present in cost data accounts for the risk of exceeding estimated cost values [ ]. the authors performed uncertainty analysis on the cost of producing biodiesel. uncertainty in their data was due to process design simulations and cost data, which were adopted either from the literature or internet-based price data. their results were helpful to identify key economic risk factors for biodiesel production plants. uncertainty present in a process design simulation may lead to underestimated design and subsequent underestimated plant economics [ ]. the source of uncertainty data in the study was due to ambiguities in the thermodynamic model performing the process simulation. these uncertainties in the thermodynamic model caused design changes in the process equipment as well as a change in the process economics. the results were helpful to identify key elements of uncertainties in a process design simulation for a process industry. uncertainty present in a wind-energy production system can influence the economic viability of the system [ ]. the study estimated uncertainties in annual energy production for a wind farm. the results helped to mitigate errors and increased the wind farm’s reliability. often, uncertainty is represented in terms of probability distribution, which indicates the likelihood of each possible outcome [ ]. the current study performs uncertainty analysis on pakistan’s energy data and provides policy guidelines based on the outcomes. the advantage of the methodology proposed in this study lies in the fact that the model can be utilized to develop an energy-policy framework considering the vagueness in energy data of a country. moreover, the methodology can help to identify core energy consumers that contribute in a substantial and least extent in energy-data uncertainty. the applications of the proposed methodology can be found in power systems, energy planning and development, and in the development of energy-policy guidelines. as highlighted through the presented literature, stochastic modeling has been a powerful tool to study uncertainty. however, to the best of the authors’ knowledge, there has been no study performed so far that could develop energy-policy guidelines based on stochastic analysis of pakistan’s energy data. this paper lists some key issues regarding energy-data management and the need for more reliable data for policy making in pakistan. inadequate energy-data management has been a known issue in many developing countries, as it is in pakistan. this paper attempts to quantify the variation in consumption statistics of different end-use sectors across different data sources. this study contributes in the existing literature by proposing a methodological framework to study uncertainty in pakistan’s energy-consumption data and presenting energy-policy guidelines in the light of the results obtained. problem statement energy-consumption data of pakistan have been reported in various literatures and through various sources. pakistan’s water and power development authority (wapda) provides annual data on the generation, consumption, distribution, and transmission of power in the country [ ]. wapda mostly deals with power data related to water and hydropower projects in the country. energy-consumption data are also published by the ministry of finance, government of pakistan [ ], under the pakistan economic survey that is issued in each fiscal year by the respective ministry [ ]. energies , , of the hydrocarbon development institute of pakistan (hdip), working under pakistan’s ministry of petroleum and natural resources, also publishes energy data in pakistan energy yearbooks on a yearly basis [ ]. electrical-energy data are also provided by the national transmission and despatch company (ntdc) pakistan. for electrical-energy projects and their data, ntdc co-ordinates with various distribution networks in the country. these networks collect energy data through their own sources. these networks include the lahore electric supply company (lesco), karachi electric supply corporation limited (kesc), faisalabad electric supply company (fesco), multan electric power company (mepco), islamabad electric supply company limited (iesco), gujranwala electric supply company (gepco), hyderabad electric supply company limited (hesco), quetta electric supply corporation (qesco), peshawar electric supply company (pesco), and the tribal area electric supply company (tesco) [ ]. energy data published by these organizations can be accessed on the ntdc webpage [ ]. the ministry of finance also publishes energy data and their associated costs and profits on an annual basis. pakistan’s energy data are also published by global economy [ ], which develop their data through various surveys. the unites states energy information administration [ ] publishes pakistan’s energy data in the international energy statistics database [ ]. having detailed studies of energy data in these many resources, it is revealed that none of the resources has reported the same energy data. for example, electricity consumption as reported by global economy in was . billion kilowatt-hours; however, for the same year, the pakistan energy yearbook reported a value of , , toe. a unit equivalency shows that the value reported by the pakistan energy yearbook was . billion kilowatt-hours, which is different than what was reported by global economy. this introduces uncertainty into the energy data and could be misleading to energy policy makers. hence the objective of the current study is to perform uncertainty analysis on pakistan’s energy data and put forward energy-policy guidelines based on the findings of the analysis. the scope of this study includes performing uncertainty analysis on energy-consumption data only. this is based on the fact that, as opposed to energy supply, energy-consumption data have more chance of being reported vaguely, as highlighted in various research works [ , ]. the energy variables in this study are the consumers, which include industry, domestic, and commercial use, agriculture, transportation, and other government businesses. energy-consumption data for each energy variable are reported separately, which indicates their non-interdependence. uncertainty analysis here does not represent the uncertainties in energy-production processes, as has been reported by some researchers [ , ]. this research does not study their interdependencies. however, there are methodologies available to study such interdependencies [ ]. to curb its energy crisis, pakistan is also focusing on renewable energy sources; however, their environmental impact is yet to be examined [ ]. . methodology stochastic analysis was performed on energy data produced from conventional energy sources, which included resources from fossil fuels (oil, gas, coal, lpg, and electricity). since some other resources, such as sustainable energy options and nuclear energy, are relatively new in pakistan, i.e., they have only been introduced in the last few decades, their data lack reliability and hence are ignored in calculating total energy consumption. for methodology demonstration purposes, analysis was performed on energy data for each fiscal year from to . the methodology presented in [ ] was extended to implement in this research. the methodological framework of this research is shown in figure . oracle® crystal ball software was used as a tool to perform a monte carlo simulation on total energy-consumption data. the following steps were followed to perform energy-uncertainty analysis followed by energy-policy recommendations: step : define the set of random inputs of the model generated in step (xi’s, i = ). in this step, six energy variables (xi), namely, domestic, commercial, industrial, agriculture, transport, and other government businesses, were assigned pdfs for each fiscal year from to . since this study deals with characterization and analysis of a large sample size of continuous variables, the probability trend of individual data quantities, also known as the pdf, was critical energies , , of to define. the central limit theorem states that a large dataset that contains various distributions, poisson, triangle, or binomial (characterized by respective pdfs), tends to show a bell curve as sample scattering goes to infinity. pdfs were defined based on the historical nature of each individual dataset. the data for consumption by domestic, agriculture, transportation, and other government businesses were characterized by normal (gaussian) distribution; as the time period and dataset were large enough, these variables converged to a normal distribution [ ]. normal distribution has the statistical parameters of standard deviation and mean. mean was the value of data around which uncertainty was being measured. commercial and industrial energy-consumption data were assigned a triangular and gamma distribution, respectively. triangular distribution was chosen for commercial energy variables as three different true values of it were observed; hence, a triangular distribution could best describe it [ ], while gamma distribution allowed to accommodate large uncertainties in energy-consumption data of the industry [ ]. table shows the details for each energy variable and their characteristics used for – data. step : generation of a parametric model. to represent the system under study, a model consisting of total energy consumption and individual variables was developed. total energy consumption is defined as the sum of energy consumed by various domestic, commercial, industrial, agricultural, transport, and other government businesses. energy-consumption data reported for each variable are the total energy data for that variable. the measurement model, a mathematical relation defined between input and output data, provided the probabilistic profile of total energy consumption as an output. energies , , x for peer review of in this step, six energy variables (xi), namely, domestic, commercial, industrial, agriculture, transport, and other government businesses, were assigned pdfs for each fiscal year from to . since this study deals with characterization and analysis of a large sample size of continuous variables, the probability trend of individual data quantities, also known as the pdf, was critical to define. the central limit theorem states that a large dataset that contains various distributions, poisson, triangle, or binomial (characterized by respective pdfs), tends to show a bell curve as sample scattering goes to infinity. pdfs were defined based on the historical nature of each individual dataset. the data for consumption by domestic, agriculture, transportation, and other government businesses were characterized by normal (gaussian) distribution; as the time period and dataset were large enough, these variables converged to a normal distribution [ ]. normal distribution has the statistical parameters of standard deviation and mean. mean was the value of data around which uncertainty was being measured. commercial and industrial energy-consumption data were assigned a triangular and gamma distribution, respectively. triangular distribution was chosen for commercial energy variables as three different true values of it were observed; hence, a triangular distribution could best describe it [ ], while gamma distribution allowed to accommodate large uncertainties in energy-consumption data of the industry [ ]. table shows the details for each energy variable and their characteristics used for – data. model f(x) define energy policy planning and implementation monitoring & checking energy audit sustainable energy policy fail pass co rr ec ti ve a ct io ns x , pr ob ab ili st ic pr of ile s x x y x m od el d is tr ib ut io n of ou tp ut q ua nt ity (y ) d ev el op m en t of e ne rg y po lic y g ui de lin es energy policy management figure . methodology for development of energy policy guidelines. figure . methodology for development of energy policy guidelines. energies , , of table . energy variables and characteristics of their probability density functions (pdfs). energy variable nature of the variable pdf *—f [ ] pdf input year – input characteristics domestic normal distribution √ πσ exp{− σ (x − u) } x = . mtoe mean = . , sd = . commercial triangular   for x < a ( |b − a ) for x = c for b > x x = c = . a = . b = . maximum value = . minimum value = . industrial gamma distribution xk− e −x θ Γ(k)θk x is location = . k is shape parameter = θ is a scale parameter = . agriculture normal distribution √ πσ exp{− σ (x − u) } x = . mtoe mean = . , sd = . transport normal distribution √ πσ exp{− σ (x − u) } x = . mtoe mean = . , sd = . other government businesses normal distribution √ πσ exp{− σ (x − u) } x = . mtoe mean = . , sd = . * pdfs adopted from [ ]. step : repeat step and n number of times. steps and were performed for individual energy-consumption data from to . in order to develop stability in the results, , iterations were performed. the simulation developed pdfs of total energy for each respective year. the pdf profile for each year was analyzed to study uncertainty in respective years. step : energy-policy recommendations and energy management. the resulting profiles of total energy consumption for each year were used to put forth future energy-policy recommendations. once the proposed energy policy passed the planning and implementation phases, the proposed energy-policy guidelines were subjected to an energy audit. . results and discussion to demonstrate the results of this work, the energy data for – are illustrated here. the results of the forecasted chart for – are shown in figure . the energy data available in the literature for – revealed that total energy consumption of that year was . mtoe. in figure , it can be seen that the base case of . remains there but is just one “number” among many others. rather than reporting a single number, analysis provides a profile instead with a full range of data. with % certainty, the value lies between . mtoe and . mtoe. as shown in figure , for the total energy of . mtoe, certainty is only . %, which shows that there is an uncertainty of . % present in the data of total energy consumption for the year – . this shows that the energy-consumption data reported have ambiguities, reducing the confidence that energy-consumption data reflect true energy consumption. there are many possible sources of uncertainty in energy-consumption data. it may be due to errors in human data collection. for example, the same instrument used by more than one person may produce different measurements, or the energy-consumption measurement device may be inaccurate or imprecise. in the next section, various reasons are reported in detail. this uncertainty in energy data could impose the risk of having ineffective energy policy. the statistical results of total energy consumption pdf are shown in table . energies , , of energies , , x for peer review of reasons are reported in detail. this uncertainty in energy data could impose the risk of having ineffective energy policy. figure . frequency chart for total energy consumption year – . figure . certainty of . mtoe for energy consumption for – . figure . frequency chart for total energy consumption year – . energies , , x for peer review of reasons are reported in detail. this uncertainty in energy data could impose the risk of having ineffective energy policy. figure . frequency chart for total energy consumption year – . figure . certainty of . mtoe for energy consumption for – . figure . certainty of . mtoe for energy consumption for – . table . statistical parameters of total energy consumption – . statistical parameter forecast values trials , base case . mean . median . mode - standard deviation . variance . skewness . kurtosis . coefficient of variation . minimum . maximum . mean std. error . energies , , of energies , , x for peer review of figure . yearly uncertainty in energy data. . . . . . . . . . . . . . . . . . . . . . . . . % time (year) figure . yearly uncertainty in energy data. energies , , of the results show that, from to , the highest uncertainty in energy-consumption data was in the fiscal year – . this indicates that there has been the least confidence in energy-consumption data in the years – for the past years’ data. the next highest uncertainty is present in the fiscal year – . the least uncertainty is present in the year – , which shows the highest certainty in energy data with the least variability. the least variability in energy data around – shows either that the energy data in this year were cross-verified among different resources or that the loss of energy was controlled through governmental measurements. this means there seems to be consistency in energy-data measurement among gop statistical measurement and international energy-reporting agencies. the results also show a steady increase in the level of uncertainty in energy data from to . since pakistan is tackling ways to curb its energy crisis, it is crucial that such high energy-data uncertainty be reduced to better plan and execute energy projects in the country. a closer examination of pakistan’s energy policies shows that pakistan started to face severe electricity shortage in ; then, it worsened with high energy demand. energy demand is much higher in summers, when the ambient temperature in some parts of the country reaches c and consumers turn on air-conditioning or cooling fans, which consume high amounts of energy. the results of the present study show an increase in uncertainty in energy data from – to – . this could be linked to an increase in electricity demand and its shortage that started in and kept on increasing. pakistan’s energy policies are based on energy demand and, as the analysis shows that there was a high level of uncertainty in energy data, the effectiveness and correctness of pakistan’s energy policy is questionable. this justifies the need to develop an effective, comprehensive, practical, and long-term energy policy based on true forecasts of energy demand and supply in the country. among many other factors, the forecasted energy is dependent on the historical use of energy. however, as this research shows, there was uncertainty present in historical energy-consumption data, so the forecasted energy values would have an associated uncertainty. this could potentially lead to mismanagement and poorly planned energy policy for pakistan. pakistan can develop much more effective energy policy by considering the uncertainty in its energy data and by eliminating potential sources of uncertainties in energy-data collection. there are various ways to eliminate such uncertainties. pakistan needs to eliminate energy theft in the country, both in the form of electricity theft and gas theft. domestic, industrial, as well as commercial energy consumption are measured by energy meters. to measure the consumption of electricity and gas, electricity meters and gas meters are installed at the location of the respective energy consumers. a fuel dispenser measures the consumption of fuel oil utilized by the consumer. this device measures the oil consumed using a numerical display/electrical pulses. though these energy meters are efficient in measuring energy consumption, due to energy theft, such devices are bypassed illegally by consumers and the government is unable to record accurate energy-consumption data. such energy theft is quite common in pakistan and is the root cause of uncertainty in energy data of the country. energy theft could be due to fraud (meter tampering), unpaid bills, billing irregularities, or theft (illegal connections) [ ]. this is because of a failure to plan and implement energy polices in the country [ ]. in particular, electricity theft is a major issue in the country. electricity is stolen by illegally connecting an electric wire to the main power source line, which bypasses the electric meter. the system is called the ‘kunda’ (hook) system in pakistan [ ]. since consumers are bypassing their electric meter and still using electricity, consumption data collected either by the government or nongovernment institutions do not reflect true consumption. hence, such consumer behavior introduces uncertainty into energy-consumption data. electricity-consumption data also have uncertainty due to poor line networks. some actual pictures are shown in figure . planning and policy making of energy generation is based on the amount of energy consumed or needed. since there is ambiguity in energy-consumption data, a true forecast of energy generation becomes vague. hence, the application of methodology in this paper can help curb the uncertainty analysis in reporting energy-consumption data and by proposing energy policy-making based on such analysis. energies , , of energies , , x for peer review of pakistan can develop much more effective energy policy by considering the uncertainty in its energy data and by eliminating potential sources of uncertainties in energy-data collection. there are various ways to eliminate such uncertainties. pakistan needs to eliminate energy theft in the country, both in the form of electricity theft and gas theft. domestic, industrial, as well as commercial energy consumption are measured by energy meters. to measure the consumption of electricity and gas, electricity meters and gas meters are installed at the location of the respective energy consumers. a fuel dispenser measures the consumption of fuel oil utilized by the consumer. this device measures the oil consumed using a numerical display/electrical pulses. though these energy meters are efficient in measuring energy consumption, due to energy theft, such devices are bypassed illegally by consumers and the government is unable to record accurate energy-consumption data. such energy theft is quite common in pakistan and is the root cause of uncertainty in energy data of the country. energy theft could be due to fraud (meter tampering), unpaid bills, billing irregularities, or theft (illegal connections [ ]. this is because of a failure to plan and implement energy polices in the country [ ]. in particular, electricity theft is a major issue in the country. electricity is stolen by illegally connecting an electric wire to the main power source line, which bypasses the electric meter. the system is called the ‘kunda’ (hook) system in pakistan [ ]. since consumers are bypassing their electric meter and still using electricity, consumption data collected either by the government or nongovernment institutions do not reflect true consumption. hence, such consumer behavior introduces uncertainty into energy-consumption data. electricity-consumption data also have uncertainty due to poor line networks. some actual pictures are shown in figure . (a) (b) (c) figure . (a) illegal electricity connections—the use of hook (kundas) on main electricity supply lines in karachi, pakistan, bypassing electric meters [ ]; (b) illegal gas connections in lahore, pakistan, bypassing gas meters [ ]; (c) conditions of electricity meters on electric poles (impossible to isolate energy consumption by consumer). photo credit: unknown. figure . (a) illegal electricity connections—the use of hook (kundas) on main electricity supply lines in karachi, pakistan, bypassing electric meters [ ]; (b) illegal gas connections in lahore, pakistan, bypassing gas meters [ ]; (c) conditions of electricity meters on electric poles (impossible to isolate energy consumption by consumer). photo credit: unknown. sensitivity analysis sensitivity analysis was performed using oracle® crystal ball software as a tool. the inputs of sensitivity analysis were energy-consumption data from to . energy consumption variables studied were the consumption of energy in industry, transportation, domestic, agriculture, commercial, and other government businesses. sensitivity analysis identified the energy variables that are contributing the most and least in introducing variability to the energy data. the results of sensitivity analysis for – are shown in figure . analysis shows the contributions of variance towards total energy consumption for – . the result shows that industrial energy-consumption data have the highest ( . %) contribution towards variability in total energy data for the year – . this indicates that the gop should adopt a rigorous policy to measure energy-consumption data for the industrial sector of the country. the results show that there is high inconsistency in the energy data of the industrial sector, which shows potential energy theft by this sector. the second- and third-highest contributions are made by the transportation ( . %) and domestic ( . %) sectors, respectively. analysis reveals that energy data for agriculture have the least contribution ( . %) towards uncertainty in total energy data for – , while commercial and other government sectors have significantly low contributions ( . % and . %, respectively). the results of the analysis extended to the remaining years are shown in figure . energies , , of energies , , x for peer review of planning and policy making of energy generation is based on the amount of energy consumed or needed. since there is ambiguity in energy-consumption data, a true forecast of energy generation becomes vague. hence, the application of methodology in this paper can help curb the uncertainty analysis in reporting energy-consumption data and by proposing energy policy-making based on such analysis. sensitivity analysis sensitivity analysis was performed using oracle® crystal ball software as a tool. the inputs of sensitivity analysis were energy-consumption data from to . energy consumption variables studied were the consumption of energy in industry, transportation, domestic, agriculture, commercial, and other government businesses. sensitivity analysis identified the energy variables that are contributing the most and least in introducing variability to the energy data. the results of sensitivity analysis for – are shown in figure . figure . sensitivity analysis of total energy consumption for year – . analysis shows the contributions of variance towards total energy consumption for – . the result shows that industrial energy-consumption data have the highest ( . %) contribution towards variability in total energy data for the year – . this indicates that the gop should adopt a rigorous policy to measure energy-consumption data for the industrial sector of the country. the results show that there is high inconsistency in the energy data of the industrial sector, which shows potential energy theft by this sector. the second- and third-highest contributions are made by the transportation ( . %) and domestic ( . %) sectors, respectively. analysis reveals that energy data for agriculture have the least contribution ( . %) towards uncertainty in total energy data for – , while commercial and other government sectors have significantly low contributions ( . % and . %, respectively). the results of the analysis extended to the remaining years are shown in figure . . . . . . . industrial transport domestic agriculture commercial other contributions to variance (%): sensitivity analysis figure . sensitivity analysis of total energy consumption for year – . energies , , x for peer review of figure . percentage contributions in data uncertainty from to . the analysis shows that from to , energy data of the industrial sector have been the highest source of uncertainty in this period. the second-highest variability in total energy data comes from the transport sector of the country and the domestic sector is the third-highest contributor towards uncertainty in energy data from to . policy guidelines a critical review of pakistan’s past energy policies reveals that their focus has been varied and has never included complexities and uncertainties in its energy systems [ ]. moreover, after the birth of the country in , the very first energy policy was formally announced after years ( ). since then, gop started to focus formally on energy-policy formulation for the country. various % % % % % % % % % % % - - - - - - - - - - -… - - - - - - - - - - - - - industrial transport domestic agriculture commercial other percentage contibutions (%) figure . percentage contributions in data uncertainty from to . energies , , of the analysis shows that from to , energy data of the industrial sector have been the highest source of uncertainty in this period. the second-highest variability in total energy data comes from the transport sector of the country and the domestic sector is the third-highest contributor towards uncertainty in energy data from to . policy guidelines a critical review of pakistan’s past energy policies reveals that their focus has been varied and has never included complexities and uncertainties in its energy systems [ ]. moreover, after the birth of the country in , the very first energy policy was formally announced after years ( ). since then, gop started to focus formally on energy-policy formulation for the country. various energy policies of pakistan, along with their respective timelines, are shown in figure . it is worth mentioning here that except for the national power policy , none of these energy policies focused on electricity theft/loss—a root cause of uncertainty in energy-consumption data. pakistan should reshape its future energy policies based on uncertainty in its energy data. this means pakistan should include vigorous guidelines to minimize and mitigate energy theft or loss. the planning and implementation of such rigorous monitoring policy would ensure robust energy-policy guidelines. it is also inferred that an energy audit should be performed to determine the viability and the variability of the developed energy policy under the umbrella of uncertain energy data. a successful energy audit would guarantee sustainable energy policy for the country. based on the preceding analysis, the following are recommended guidelines to be included in the development of energy policy for pakistan. ( ) technical and nontechnical control of energy-line losses. in an energy transmission and distribution system, energy-line losses occur due to conversion of energy or electricity into heat, which can never be recovered or utilized. energy losses also occur due to the transformation of energy into electromagnetic energy, which is essentially wasted. though such losses cannot be eliminated completely even in the most efficient energy system, they can be reduced to their minimal. as presented in this study, the pakistan energy sector is facing huge energy-line losses and such losses need to be controlled. in light of the above analysis, this objective can be achieved by either considering nontechnical or technical solutions, or a combination of both. nontechnical solutions may include legal and regulatory accountability of energy consumers in pakistan, providing financial rewards for reporting energy theft, random checks on energy consumers belonging to different sections of society, and the enforcement of the law; this should include fair implementations of fines and imprisonment for stealing national energy resources. technical solutions include advanced and sophisticated devices to monitor energy consumption, the details of which are presented in section of the policy guidelines presented in this paper. rolling blackouts in pakistan have not only paralyzed pakistan industries but have also significantly influenced the gdp of the country. ( ) national- and regional-level energy audit system. considering the results of the uncertainty analysis, it is quite pertinent that pakistan’s industrial sector has the highest uncertainty associated with energy consumption. based on this result, it is suggested that pakistan energy-policy makers should include regional and local energy audit systems while developing energy polices for pakistan’s industries. there is a need to develop a new energy-audit department (or increase the effectiveness of existing audit departments) that can audit the energy consumption of pakistan’s industries. currently, there are various energy-audit departments in the country; these are the national productivity organization [ ]; the national energy efficiency and conservation authority [ ], created due to the introduction of the national energy efficiency and conservation act by the national assembly and the senate of pakistan [ ]; and the national cleaner production centre [ ]. these government departments either do not effectively perform energy audits or do not have energy audits on a regular basis. energies , , of ( ) faulty energy meters. as revealed through uncertainty analysis, faulty or sluggish energy-measurement meters introduce uncertainty in energy data. the energy policy of pakistan should include the replacement or repair of sluggish and/or faulty energy-measurement meters. such an addition to energy policy would facilitate the control of unmetered energy consumption that results in energy as well as financial loss. to reduce uncertainty in energy data, there is a need to test energy-consumption meters at regular intervals. the use of smart meters could help to achieve practical implementation of this proposed energy policy. other than smart meters, the use of meter boxes and their proper sealing can also ensure no tampering is done. the impact of energy or power theft not only limits government revenue but also affects power availability and low voltage quality causing voltage dips, adding additional load to the energy system. ( ) development of a single hub for collecting energy data. as highlighted in the research problem statement, various government and/or nongovernment departments collect energy-consumption data. gop should establish one department that can monitor and collect energy-consumption data. this department should be able to collect energy data from streets to big cities to the whole country. the usual system of collecting power-consumption data is by meter reader. as shown in figure c, the poorly managed and unorganized conditions make it hard for a reader to note the correct data. therefore, it is proposed that pakistan should switch to prepayment meters that work only when the consumer adds credit to the meter. this not only eliminates the need to record power utilization by consumers but would also ensure no power theft. other methods include the use of electronic tampering-detection meters, which automatically detect meter bypasses, meter tampering, and meter disconnection (as what takes place in western countries). another remedy is the use of antitheft cables and plastic meter encasements, which are meter seals made of hard plastic encasements. ( ) vigilance programs for industrial, transport, and domestic sectors. the uncertainty analysis showed that there are three major energy-consuming sectors with highest variations in their energy-data reporting. these are the industrial, transport, and domestic sectors. pakistan energy policy should include an industrial, transport, and domestic vigilance program to reduce energy losses and uncertainties in energy data. such measures should include separate feeders for industrial, transportation, and domestic use. this would introduce transparent accountability for these energy sectors. considering agriculture consumers, there is a need for a one-consumer one-transformer policy. the agricultural sector of pakistan should be made accountable for the use of poor quality equipment for water pumping in rural areas. ( ) superconductive transmission. all power plants, either based on natural gas, coal, or petroleum, work on the same principle. fuel is burned to release heat, which is used to convert water into steam, and steam spins turbines that finally generate electricity. the long-distance transmission of generated electricity is performed through high-voltage lines. losses in high-voltage-carrying lines could be due to the conversion of electricity into heat; subsequently, heat is lost to the environment. this loss could also be due to sagging of high-transmission power lines. similar to other countries, power plants in pakistan are remote, away from populated areas, and power losses due to line-sagging problems can be seen with electric-power transmission. another study also confirms that pakistan has higher transmission and distribution losses than countries in europe, africa, and the middle east [ ]. hence, it is proposed that pakistan energy policy should ensure that superconducting materials are used in transmission lines to control losses in electricity transmission and distribution. ( ) detailed distribution system. considering the high level of energy data uncertainty, pakistan needs to revise its energy-distribution system. the energy policy of pakistan should include studying the existing energy-distributing system and developing guidelines for a new and improved distribution system. this improved system should be based on expected load development considering the energy-data uncertainties presented in this paper. energies , , of energies , , x for peer review of figure . timeline of pakistan’s energy policies showing various accomplishments. power hydropower private projects power generation renewable energy industry collaborative national energy national power power generation figure . timeline of pakistan’s energy policies showing various accomplishments. energies , , of in order to implement these policies, there is a need for good governance, implementation of laws pertaining to energy, transparency in the government and private energy sectors, competence, and engagement with the public over energy theft. it is pertinent to mention here that uncertainty in energy-consumption data is also a common issue even in many developed countries due to the complexity of consumption data itself and the variation in survey designs. . conclusions and policy implications pakistan is facing a severe energy crisis, and with population growth, this energy crisis is becoming overwhelming. this calamity is not only darkening the streets of pakistan but also affecting the economy of the country. hence, there is a need to define new or re-evaluate the existing energy policy of pakistan on a regular or annual basis. effective energy management is only possible when all variabilities in energy data are considered. energy policies of pakistan are based on past energy data to predict future growth. in this study, a stochastic analysis was performed on pakistan’s historical energy-consumption data ( – ) using a monte carlo simulation. energy-consumption variables were assigned respective pdfs based on the historical nature of individual datasets. total energy consumption was defined as the sum of energy consumed by commercial, domestic, agriculture, industrial, transportation, and other government business sectors. a simulation model was set up to find total energy consumption for the respective years. the simulation was performed for , iterations to develop probabilistic profiles of total consumption for each year. the developed profiles were analzsed and the energy-policy guidelines were presented in the light of the results obtained. the study reveals that there has been uncertainty in the past energy data of pakistan. this not only leads pakistan to underestimate its energy consumption, but also causes ambiguity in previously defined energy policies of the country. the current study performed stochastic modeling and found uncertainty in energy data for pakistan from to . none of pakistan’s energy policies has been effective due to the fact that these policies ignored the ambiguities in energy data. except for the national power policy of , none of the energy policies of pakistan considered tackling energy theft in the country. energy theft introduces uncertainties in energy-consumption-data recording. the findings of stochastic modeling are used to recommend energy-policy guidelines based on the uncertainty principle. the analysis concluded by providing seven new recommended guidelines that should be part of new energy policy of the country. all these guidelines involve tackling uncertainty in energy data and making consumers more accountable for their energy consumption. this study suggested implementing national- and regional-level energy-audit systems to achieve a sustainable energy policy for the country. author contributions: conceptualization, z.s.; methodology, z.s., a.j.; software, z.s.; validation, z.s., a.j.; formal analysis, z.s., a.j.; investigation, z.s.; resources, z.s., a.j.; data curation, z.s., a.j.; writing-original draft preparation, z.s.; writing-review & editing, a.j.; visualization, z.s., a.j. funding: this research received no external funding. acknowledgments: authors would also like to thank queen elizabeth ii library, memorial university of newfoundland, st. john’s, canada, to fund apc for this publication. conflicts of interest: the authors declare no conflict of interest. references . u.s. census bureau. world population clock. available online: http://www.census.gov/popclock/ (accessed on august ). . sheikh, m.a. energy and renewable energy scenario of pakistan. renew. sustain. energy rev. , , – . 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http://www.enercon.gov.pk/home.html http://www.ncpc.com.pk/services_energy.html http://www.ncpc.com.pk/services_energy.html http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	introduction 	methodology 	results and discussion 	conclusions and policy implications 	references wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, 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incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ ichai et al. critical care , : http://ccforum.com/content/ / / commentary sodium lactate for fluid resuscitation: the preferred solution for the coming decades? carole ichai , , , *, jean-christophe orban , , , and eric fontaine see related research by nalos et al., http://ccforum.com/content/ / /r abstract in a recent issue of critical care, . m sodium lactate infusion for hours was reported to increase cardiac output in patients with acute heart failure. this effect was associated with a concomitant metabolic alkalosis and a negative water balance. growing data strongly support the role of lactate as a preferential oxidizable substrate to supply energy metabolism leading to improved organ function (heart and brain especially) in ischemic conditions. due to its sodium/chloride imbalance, this solution prevents hyperchloremic acidosis and limits fluid overload despite the obligatory high sodium load. sodium lactate solution therefore shows many advantages and appears a very promising means for resuscitation of critically ill patients. further studies are needed to establish the most appropriate dose and indications for sodium lactate infusion in order to prevent the occurrence of severe hypernatremia and metabolic alkalosis. lactate infusion was responsible for an improved myocar- in a recent issue of critical care, nalos and colleagues evaluated the effect of . m sodium lactate (sl) solution on cardiac function in patients presenting acute heart failure [ ]. the key result was that -hour infusion of sl resulted in increased cardiac output, whereas it did not change in the control group receiving ringer lactate. this difference could be accounted for, in large part, by an augmentation in stroke volume. further, patients receiving sl developed metabolic alkalosis, hypokalemia and hypernatremia, while their water balance was strongly negative. these findings highlight the complexity of the beneficial effects induced by sl infusion. * correspondence: ichai@unice.fr medicosurgical intensive care unit, saint roch university hospital, rue pierre dévoluy, nice, france inserm, u , institute for research on cancer and aging of nice (ircan), ‘aging and diabetes’ team, nice, france full list of author information is available at the end of the article © ichai et al.; licensee biomed central lt months following its publication. after this attribution license (http://creativecommons.o reproduction in any medium, provided the or dedication waiver (http://creativecommons.or unless otherwise stated. first, hyperlactatemia is a good marker of poor outcome in critically ill patients. tissue hypoxia is responsible for an increased lactate production resulting from glycolysis [ , ]. proponents of intensive intervention therefore strongly believed that lactate was, to say the least, a useless waste end product, if not a toxic one. however, the cause– effect relationship is not clearly demonstrated. indeed, growing data support the notion that lactate production is not deleterious, but rather is an adaptative response allow- ing one to maintain an appropriate energetic metabolism in the case of shock or organ failure [ - ]. nevertheless, the effect of solutions containing high lactate concentra- tion in these situations is still a matter of debate. evidence is now accumulating that lactate is a preferred substrate readily oxidizable in energy crisis conditions [ - ]. in physiological basal situations, the myocardium functions using energy from beta-oxidation of fatty acids. when oxygen availability is limited, myocardial energy metabolism switches from lipid oxidation to carbohydrate oxidation [ ]. previous studies have already shown that dial function in patients with septic shock or after cardiac surgery [ , , ]. the current study reproduces these results in patients with acute heart failure [ ]. levy and colleagues demonstrated that lactate deprivation worsened myocar- dial metabolism and performance in rats with septic shock [ ]. this effect is believed to be due to, for the greater part, the preferential lactate metabolism supplying sufficient energy to the myocardium. however, this hypothesis should be confirmed using direct measurements of lactate oxidation in the heart. similar results have been reported in normal and injured brain, and confirmed the role of lactate as an important source of energy [ , , ]. allaman and colleagues described the essential impact of lactate metabolism in the astrocyte–neuron coupling function [ ]. in traumatic brain injury, sl infusion was more effi- cient than mannitol to decrease raised intracranial pressure [ ]. in a later study, a systematic sl infusion over hours d. the licensee has exclusive rights to distribute this article, in any medium, for time, the article is available under the terms of the creative commons rg/licenses/by/ . ), which permits unrestricted use, distribution, and iginal work is properly credited. the creative commons public domain g/publicdomain/zero/ . /) applies to the data made available in this article, mailto:ichai@unice.fr http://creativecommons.org/licenses/by/ . http://creativecommons.org/publicdomain/zero/ . / http://ccforum.com/content/ / / ichai et al. critical care page of , : http://ccforum.com/content/ / / decreased by % the incidence of elevated intracranial pressure episodes [ ]. the second point raised by nalos and colleagues is the induction of metabolic alkalosis by sl infusion [ ], which reflects the probable lactate oxidation. according to the stewart concept, the exogenous lactate enters into the cells (metabolized anion) while exogenous sodium remains in the plasma (nonmetabolized cation). these modifications in turn induce an increase in the strong ion difference and in the plasma bicarbonate concentra- tion [ ]. in agreement with other studies, sl infusion induced metabolic alkalosis and hypokalemia and pre- vented hyperchloremic acidosis. the authors emphasized that metabolic alkalosis could improve cardiac function [ ]. however, it is known that metabolic alkalosis de- creases coronary artery blood flow and worsens cardiac arrhythmias, hypokalemia and cardiac contractility. on the other hand, prevention of hyperchloremic acidosis by the balanced sl solution could lead to an improve- ment in organ function [ , ]. the global consequences of such multiple and intricate metabolic modifications on cardiac function remain questioned. third, the infusion of a large amount of sodium in patients with acute heart failure represents a clear danger as sodium restriction is the classic treatment for this condi- tion. surprisingly, the authors showed that the -hour and -hour water balances were strongly negative in patients receiving sl compared with the control group. this finding is in agreement with previous studies performed in cardiac surgery and traumatic brain-injured patients [ , ]. the mechanism by which sl influences water balance is not clear. a lower required volume of infusion and/or a higher urine output have been previously reported as a conse- quence of the sodium/chloride imbalance of this solution [ , ]. unfortunately, these data are lacking in the study by nalos and colleagues. independently of the underlying mechanism, the resulting effect provides a substantial ad- vantage in favor of sl infusion because fluid overload is as- sociated with an increased morbi-mortality in various critical conditions, especially cardiac failure [ ]. in conclusion, the study by nalos and colleagues pro- vides additional arguments to strongly consider sl as a valuable means for resuscitation. thanks to its high lactate and low chloride concentrations, sl offers substantial clin- ical improvement in organ functions, especially for the heart and brain. abbreviation sl: sodium lactate. competing interests the authors declare that they have no competing interests. author details medicosurgical intensive care unit, saint roch university hospital, rue pierre dévoluy, nice, france. inserm, u , institute for research on cancer and aging of nice (ircan), ‘aging and diabetes’ team, nice, france. cnrs, umr , ircan, nice, france. university of nice – sophia antipolis, nice, france. lbfa – inserm , university joseph fourier, grenoble, france. published: references . nalos m, leverve xm, huang sj, weisbrodt l, parkin r, seppelt im, ting i, mclean as: half-molar sodium lactate infusion improves cardiac performance in acute heart failure: a pilot randomized controlled clinical trial. crit care , :r . . bakker j, nijsten mwn, jansen tc: clinical use of lactate monitoring in critically ill patients. ann intensive care , : . . garcia-alvarez m, marik p, bellomo r: stress hyperlactataemia: present understanding and controversy. lancet diabetes endocrinol , : – . . levy b, mansart a, montenmont c, gibot s, mallie jp, lacolley p: myocardial lactate deprivation is associated with decreased cardiovascular performance, decreased myocardial energetics and early death in endotoxic shock. intensive care med , : – . . van hall g: lactate kinetics in human tissues at rest and during exercise. acta physiol , : – . . wyss mt, jolivet r, buck a, magistratti pj, weber b: in vivo evidence for lactate as a neuronal energy source. j neurosci , : – . . stanley wc, recchia fa, lopaschuk gd: myocardial substrate metabolism in the normal and failing heart. physiol rev , : – . . mustafa i, leverve xm: metabolic and hemodynamic effects of hypertonic solutions: sodium-lactate versus sodium chloride infusion in postopera- tive patients. shock , : – . . leverve xc, boon c, hakim t, anwar m, siregar e, mustafa i: half-molar sodium-lactate solution has beneficial effect in patients after coronary artery bypass grafting. intensive care med , : – . . bouzat p, sala n, suys t, zerlauth jb, marques-vidal p, feihl f, bloch j, mes- serer m, levivier m, meuli r, magistretti pj, oddo m: cerebral metabolic ef- fects of exogenous lactate supplementation on the injured human brain. intensive care med , : – . . ichai c, armando g, orban jc, berthier f, rami l, samat-long c, grimaud d, leverve x: sodium-lactate vs mannitol in the treatment of intracranial hypertensive episodes in severe traumatic brain-injured patients. inten- sive care med , : – . . allaman i, bélanger m, magistretti pj: astrocyte–neuron metabolism relationships: for better and for worse. trends neurosci , : – . . ichai c, payen jf, orban jc, quintard h, roth h, legrand r, francony g, leverve x: half-molar sodium lactate to prevent intracranial hypertensive episodes in severe traumatic brain-injured patients: a randomized con- trolled trial. intensive care med , : – . . stewart pa: independent and dependent variables of acid–base control. resp physiol , : – . . yunos lm, bellomo r, hegarty c, story d, ho l, bailey m: association between a chloride-liberal vs chloride-restrictive intravenous fluid. jama , : – . . mccluskey sa, karkouti k, wijeysundera d, minkovich l, tait g, beattie ws: hyperchloremia after noncardiac surgery is independently associated with increased morbidity and mortality: a propensity-matched cohort study. anesth analg , : – . . vincent jl, sakr y, sprung cl, ranieri vm, reinhart k, gerlach h, moreno r, carlet j, le gall jr, payen d, sepsis occurrence in acute ill patients investigators: sepsis in european intensive care units: results of the soap study. crit care med , : – . cite this article as: ichai et al.: sodium lactate for fluid resuscitation: the preferred solution for the coming decades? critical care jul . /cc , : http://ccforum.com/content/ / / 	abstract 	abbreviation 	competing interests 	author details 	references scientia iranica a ( ) ( ), { sharif university of technology scientia iranica transactions a: civil engineering www.scientiairanica.com review article upcoming challenges of future electric power systems: sustainability and resiliency m. fotuhi-firuzabad�, a. safdarian, m. moeini-aghtaie, r. ghorani, m. rastegar and h. farzin center of excellence in power system control and management, school of electrical engineering, sharif university of technology, tehran, iran. received march ; accepted july keywords power industry challenges; power industry solutions; future power systems; resilient power systems; sustainable power systems. abstract. going back and taking a quick glance at the history of developed countries prove that prosperity of any society is tightly intertwined with resiliency and sustainability of its preliminary infrastructures. surely, in modern societies, electricity is among the most important infrastructures whose resiliency and sustainability are a key driving force toward development of the society. this is veri�ed by the fact that since the industrial revolution, per capita electricity consumption has been taken as a key index showing the level of economic development and standard of living in a country. this paper focuses on the concept of resiliency and sustainability of electric power systems. the paper, initially, introduces the concept and evaluation procedure of power systems resiliency. then, it strives to introduce the most challenging issues faced by resilient and sustainable power grids. the challenging issues are electricity load growth, energy crisis, environmental emissions and climate changes, unexpected events, aging infrastructures, and cyber challenges. then, the most e�ective solutions proposed by power industry scientists and engineers are discussed. the solutions are asset management, renewable energy resources, demand response, controlled islanding and micro-grids, automation, self- healing, and monitoring systems. finally, a typical sustainable and resilient power system is described. © sharif university of technology. all rights reserved. . introduction the concept of resiliency, which was stimulated by environmentalism, focuses upon the requirements to counter the occurrence and impact of catastrophic events on urban areas. in particular, the concept of resiliency is used to describe the ability of cities and regions in moving toward more `safe' and `sustainable' *. corresponding author. tel.: + e-mail addresses: fotuhi@shairf.edu (m. fotuhi-firuzabad); safdarian@sharif.edu (a. safdarian); moeini@sharif.edu (m. moeini-aghtaie); ghorani rahim@ee.sharif.edu (r. ghorani); mohammadrastegar@shirazu.ac.ir (m. rastegar); farzin@ee.sharif.edu (h. farzin) communities [ ]. as electric power infrastructures have contributed a lot to the safety and sustainability of communities, upgrading the current infrastructure to a resilient one is one of the major goals which portray the future resilient urban areas. electric power system, with its humble beginning in the s, has been matured into a large-scale industry. taking the role of a basic necessity for modern societies, electricity consumption around the world experiences a fast growing trend. in response, the worldwide electricity production nowadays has reached near billion kilowatt-hours per year (see figure ) [ ]. as new gears and machines have been made based on electricity, human life quality has been m. fotuhi-firuzabad et al./scientia iranica, transactions a: civil engineering ( ) { figure . electricity production around the world (twh). intertwined more and more with continuity and quality of electricity services. the proliferation of electric devices in human life has obliged the power industry to pay a greater attention to the service reliability. on the other hand, electricity industry encoun- ters a large number of challenging issues in meeting reliability requirements of the society. electric power systems are among the most complicated man-made structures through the history with a large number of components scattered in vast areas. this, beside aging infrastructures, growing loads, natural disasters, energy crisis, and proliferation of renewable energies, makes meeting the reliability requirements a very di�- cult task. on the other hand, huge and almost always growing needs for intensive capital reinforcements in power systems are in an obvious contradiction with tightly limited budgets in this industry. these all force the industry to explore some innovative ideas useful for utilizing existing electricity infrastructures in a more e�ective manner thereby guaranteeing a sustainable and resilient system. asset management, self-healing systems, precise monitoring and visualization systems, prompt automation systems, controlled islanding and micro-grids, demand response, and renewable energy sources are among the most e�ective ideas which were proposed by power system engineers to propel the industry toward a more sustainable and resilient power system. a sustainable power system should be able to tolerate unexpected events, such as equipment outages, severe weather conditions, natural disasters, and fuel shortages, to name just a few. synonymously, in a sustainable system, customer service continuity and reliability should be preserved during such events. a resilient power system is able to e�ectively and quickly recover the likely load interruptions following an unexpected event such as equipment outages and natural disasters. the concept of asset management is a cost-e�ective way to e�ciently manage asset related procedures, i.e. procurement, operation, maintenance, and disposal of assets, and to help system owners to satisfy their �nancial goals while meeting benchmarked reliability and resiliency standpoints. advanced mon- itoring infrastructures provide system operators with more precise situational awareness and allow them take more e�ective remedial actions. automated power systems provide system operators with remote control actions, which in turn result in prompt remedial actions. the controlled islanding and micro-grids by isolating autonomous areas of the system intend to serve electricity needs of end users which are located in healthy areas. demand response is an e�ective load shaping tool which can be utilized to alleviate operational limits such as network overloads and under- voltages. finally, renewable energy sources by declin- ing the share of fossil fuel-�red generating units in load procurement can be an e�ective solution for energy crisis. therefore, moving toward a sustainable power system calls for changes not only in the way electrical energy is supplied, but also in the way it is consumed. based on the above discussions, one can come to this point that power industry is faced with several challenging issues that should be properly addressed to promise a bright future for the system. in addition, as mentioned heretofore, a large number of e�cient as well as economical solutions have been found to counter the critical issues. as a complementary to the published works in this area, this paper describes the major challenges encountered by the industry to move toward a resilient and sustainable power system. in addition, this paper reviews the most e�ective ways available to enhance the system resiliency and sustainability following unpredicted events including both endogenous and exogenous failures. a brief explanation on how the ways cover concerns about resiliency and sustainability of power systems is the other goal of this paper. discussing the challenges and solutions, an envisioned power system, which is equipped with e�ective tools to reach an appropriate level of resiliency and sustainability, is also introduced. . resiliency concept and evaluation in power systems as mentioned in the previous section, over the past decades, the international society and speci�cally power utility managers have paid a great attention to preventing catastrophic losses and managing disruptive impacts of both man-made and naturally happening threats and hazards. to this end, there exist several di�erent de�nitions for a resilient system which is immune to both man-made and naturally occurring threats. in the following, a few of the most relevant de�nitions for \resilience" are given [ ]: � resilience is \a measure of the persistence of systems and of their ability to absorb change and disturbance and still maintain the same relationships between populations or state variables" [ ]; m. fotuhi-firuzabad et al./scientia iranica, transactions a: civil engineering ( ) { � resilience is \the capacity to cope with unantic- ipated dangers after they have become manifest, learning to bounce back" [ ]; � resilience is \the capacity to adapt existing re- sources and skills to new situations and operating conditions" [ ]; � resilience is the \ability to resist, absorb, recover from, or successfully adapt to adversity or a change in conditions" [ ]. resiliency is a system concept which is related to some other system concepts such as reliability or survivability. actually, in the literature on electrical engineering, resiliency and reliability have almost the same meaning. the term reliability is the probability that a device or system performs its purpose adequately for the period of time intended under the operating conditions encountered. when it comes to the power grid, reliability can be de�ned as the ability of the grid to perform its intended function, which is serving electricity needs of consumers and other preliminary infrastructures in a continuous and of course eco- nomic manner. in the electric utility industry, system reliability has two fundamental aspects of adequacy and security. adequacy refers to the existence of su�cient generation, transmission, and distribution facilities to produce and transport electric energy to end users taking speci�ed outage events into account. security, however, refers to the ability of a system to withstand any disturbances arising within the system. these include local and widespread disturbances as well as unexpected sudden loss of generators, network components, or loads resulting in system instability and cascading outages. needless to mention, a reliable power system refers to a system which is both adequate and secure. in order to recognize adequacy and security, power system conditions can be described by several operating states in terms of the degree to which ade- quacy and security considerations are satis�ed. these operating states are designated as normal, alert, emer- gency, extreme emergency, and restorative as shown in figure [ ]. these states are determined in terms of the degree to which security margins are satis�ed. in the normal state, the system is capable to serve the existing total load. in this state, su�cient margin is available such that any likely disturbance, speci�ed by some criteria, can be tolerated. a criterion such as the loss of any single component depends on the planning and operating philosophy of the service provider. the system is in the alert state if all the constraints are within limits but there exist some disturbances which cannot be tolerated by the system and following which electricity service interruption is not avoidable. in the emergency state, some of the system operational constraints are violated. in this state, the system is figure . system operating states diagram. figure . three steps of reliability assessment procedure for a power system. still intact but appropriate remedial actions must be taken into account to restore the system to at least the alert state; otherwise, the system will transfer from the emergency state to the extreme emergency state. in the extreme emergency state, system operational con- straints are violated and some load points experience electricity service interruption. according to the above model, for a system, probability of being in the �vefold operating states illustrates the degree of system well-being. in order to estimate probabilities of the states, a three-step proce- dure, which is shown in figure , must be performed. as can be seen, in the �rst step, likely events, including both man-made and naturally happening disturbances and hazards, are selected. in the next step, the selected events are analyzed and their circumstances are obtained. clearly, some of the selected events lead to violations of operational constraints, which can be mitigated by appropriate remedial actions, and some result in service interruptions. the achieved consequences associated with the selected events are combined with their occurrence probability to form state probabilities as reliability indices in the third step. the reliability evaluation procedure, although seems to be straight, is a very challenging process mainly due to the required data and the huge number of m. fotuhi-firuzabad et al./scientia iranica, transactions a: civil engineering ( ) { likely events. the former origin of di�culty goes back to the fact that almost all of man-made and naturally happening disturbances are stochastic in nature and their occurrence highly depends on several a�ecting pa- rameters such as weather condition. for example, the failure rate associated with power system components usually increases during severe weather conditions. in order for an analysis to lead to reasonable and accurate results, likely events and their occurrence probabilities must be determined through comprehensive analyses of historical recorded data of the system during dif- ferent conditions (e.g., di�erent weather conditions). the latter origin of di�culty in reliability assessment procedures goes back to the enormous number of power system components which are scattered in vast areas with di�erent weather conditions. this substantially increases the number of likely events which can occur in the system. note that analyzing a huge number of events is exhaustive and computationally expensive. for these reasons, there have been developed sorts of commercially available software packages for both data collection and reliability analyses. the iran grid management company (igmc), which is in charge of the iranian power system, under the umbrella of a project with sharif university of technology (sut), studied almost all of the available worldwide power system reliability assessment software packages, and based on their pros and cons, it is going to develop a comprehensive software package for the national grid. it can be concluded from the above discussion that the system must be able to resist likely distur- bances as well as to recover to its normal condition following any disturbances. even though resiliency is a more comprehensive concept, both resiliency and reliability include some aspects of resistance against disturbances and recovering from them. both aspects become more meaningful when dealing with very large- scale and complex systems such as power grid. . challenges this section describes the major challenging issues which may be encountered while the power industry intends to move toward a resilient and sustainable system. the issues are load growth, energy crisis, emissions and climate changes, unexpected events, aging infrastructure, and cyber challenges. . . load growth electricity load growth is a challenging issue which should be considered by the power industry. the system load increases as new customers are added to the grid or existing customers add new appliances or re- place their existing equipment with devices that require more power. load growth is in
uenced by many factors figure . annual peak load variation in iran from to . including the national economy, income per capita, power management, prices, policies, and conservation. the annual energy outlook (aeo ) [ ], prepared by the energy information administration (eia), presents long-term projections of energy supply, demand, and prices to . according to this report, the mean incremental growth rate of annual electricity consumption will be . % due to new uses of electric- ity. it may vary in di�erent countries. for instance, figure [ ] shows the load demand variation in iran from to , where the load growth on average is %. besides the mentioned load growth, proliferation of electric vehicles, which is triggered by environmental concerns, will add a signi�cant load to the power industry. a typical plug-in electric vehicle requires . - . kwh of charging power for a mile of driv- ing. assuming average daily trip with - miles of length, electric vehicles need - kwh of electrical energy daily. these load growth, if it is not man- aged e�ectively, may degrade power systems reliability. in addition, unbalanced load growth, resulting from unequal single-phase and double-phase loads such as plug-in vehicles, could result in degradation of power quality, increased harmonics and voltage problems, and increasing line losses. . . energy crisis secure and price-consistent sources of primary energies are among critical prerequisites for modern societies. primary energy is referred to as an original energy form which can be found in the nature and has not been subjected to any transformation process. the major sources of primary energies are fossil fuels (coal, oil and natural gas), biofuels-wood, wooden wastes, agricultural wastes, etc. figure [ ] demonstrates the share of di�erent primary energy forms in worldwide energy consumption. as can be seen, oil, coal, and natural gas has made up almost % of primary energy production. as mentioned earlier, fossil fuels have the largest share in the sources to produce electricity worldwide. m. fotuhi-firuzabad et al./scientia iranica, transactions a: civil engineering ( ) { figure . worldwide consumption of primary energy sources. table . world reserves of natural gas. proved reserves (trillion cubic meters) % of world reserve remaining years of extraction world iran russian federation qatar turkmenistan us saudi arabia united arab emirates venezuela nigeria algeria however, fossil fuel reserves are not uniformly dis- tributed over the earth. tables to [ ] respectively show the share of di�erent countries from the remaining resources of natural gas, coal, and crude oil. as can be seen, a large number of the primary energy reserves are owned by a few countries. therefore, countries with inadequate reserves of fossil fuels face serious concerns about primary energy availability since functionality of their power systems is highly dependent on others. besides, according to the most optimistic forecasts done, the reserves of fossil fuels last for years for coal, years for natural gas, and years for crude oil. based on the above discussions, power industries, whose main sources of primary energy depend on fossil fuels, will encounter the challenging issue of energy crisis. table . world reserves of coal. proved reserves (trillion cubic meters) % of world reserve remaining years of extraction world us russian federation china australia india germany ukraine kazakhstan south africa colombia table . world reserves of crude oil. proved reserves (trillion cubic meters) % of world reserve remaining years of extraction world venezuela saudi arabia canada iran iraq kuwait united arab emirates russian federation libya nigeria . . emissions and climate changes a power system must be environmentally friendly to support a sustainable society. therefore, alleviating climate changes and environmental concerns are among challenging issues which are encountered by the power industry. moreover, since greenhouse gases generated by electric power plants are much easier to monitor and control than emissions from other sources such as vehi- cles, the electricity sector has always been considered as a primary target in emission control programs. fossil fuels burnt to supply the global electricity demand account for releasing annually over million tons m. fotuhi-firuzabad et al./scientia iranica, transactions a: civil engineering ( ) { of carbon dioxide (co ), which is equivalent to . % of total co emissions. it is predicted that the annual co emission will surpass million tons by [ ]. nowadays, in worldwide electricity production, coal continues to have the largest share by %, which provides electricity with high greenhouse gases and emissions. . . unexpected events unexpected events are the major contributor in jeop- ardizing power systems resiliency and sustainability. as mentioned heretofore, power systems have been designed and operated to withstand a great major- ity of disturbances while being able to supply to customers. however, despite the arduous e�orts to build a resilient and sustainable system, unexpected disturbances always threaten security and functionality of the system. in addition, interconnected nature of the system increases the probability of fault propagation, which can interrupt the service to a large number of customers. in the next paragraph, main roots of system events are initially categorized followed by a brief discussion on the expected consequences of outages and blackouts. in the electrical engineering context, faults are categorized based on their electrical nature and du- ration. accordingly, faults are generally divided into two major groups of open and short-circuit faults, which can be further classi�ed based on the number of involved electrical phases [ ]. following an event, repair/replacement expenses, likely losses of the service provider, and likely damage costs to customers are the three main contributors to the overall damage cost. it is clear that damaged components must be re- paired/replaced to fully restore the system functional- ity. this procedure incurs maintenance or replacement costs to the service provider. besides, since the system, whose electricity service is interrupted, is unable to supply to customers, the revenue from selling electricity to the customers is lost as well. at last, monetary damages and loss of comforts are imposed on customers who experience service interruptions. among the three terms, since prosperity of customers' activities is highly intertwined with electric energy, any interruption in the services paralyzes customers; as a consequence, interruption costs to customers are much more than the losses of maintenance and service providers [ ]. in fact, the type of customers and outage duration are the two important factors that determine the damage to customers. to delineate the subject, table lists the estimated customer interruption costs for di�erent outage durations and customer types [ ]. blackouts or large outage events are the most catastrophic events that can happen in a power sys- tem. these catastrophic events usually originate in either natural disasters such as 
oods and earthquakes or propagation of component outages through power systems. cascading outages, which are de�ned as a sequence of dependent failures, lead to power system weakness and may spread through the system and cause blackouts. a propagation sequence can be due to the fact that power systems are weakened following an outage as well as due to protection system malfunctions or system operator errors. in such catastrophic events, extensive interrupted areas along with usually long restoration time worsen the situation and exacerbate their monetary losses and social consequences com- pared to events with limited a�ected areas and short durations. to demonstrate both the vulnerability of modern power systems and the catastrophic conse- table . estimated average electric customer interruption costs in , in us dollars. interruption cost interruption duration < min min hr hr hr medium and large c&i cost per event , , , , , cost per average kw . . . . . cost per un-served kwh . . . . . small c&i cost per event , , cost per average kw . . . , , cost per un-served kwh , . . . . residential cost per event . . . . . cost per average kw . . . . . cost per un-served kwh . . . . . m. fotuhi-firuzabad et al./scientia iranica, transactions a: civil engineering ( ) { table . the ten most severe blackouts. country year a�ected population duration new zealand , weeks brazil , , ( % of the territory) hours india , , hours u.s.a. & canada , , days italy , , hours spain , , blackouts within days indonesia , , hours south west europe , , hours brazil + paraguay , , mins to hours brazil , , hours quences of service disruption, table lists the ten most severe blackouts considering a�ected population and duration [ ]. cascading outages have been reported as the most important cause of recent major blackouts. . . aging infrastructures a large number of components in the existing power systems have been designed and installed decades ago. as a matter of fact, by passing the time, failure rates of these components have increased signi�cantly, which degrade ability of the grid to handle unexpected events. this is due to the fact that failure frequency of an old component is much more than that of a similar but new component. aging power system components, in order to properly perform their functionality with reasonable failure rates, need regular costly mainte- nance and even replacement actions. these actions, however, seem very di�cult considering number and geographical disparity of the components and also tightly limited budgets of the industry. therefore, power industry is faced with the key challenging issue of aging infrastructures, which must be overwhelmed to achieve a resilient and sustainable power system. . . cyber challenges while modern communication, control, and computing technologies o�er tremendous opportunities to improve electric power system response and resilience to failure, they also render the grid vulnerable to intentional attacks from internal or external parties. this in fact increases the risk of compromising reliable and secure power system operation. in general, security attacks to the electricity infrastructure can be classi�ed into physical and cyber threats. in case of physical threats, although the attacks may be troublesome and incur extra cost to the local grid owner, they are likely to a�ect only a small portion of the overall grid. on the other hand, the number of documented cyber-attacks and intrusions worldwide has been rising very rapidly in recent years. due to the increasingly sophisticated nature and speed of malicious code, intrusions, and attacks, human responses may be inadequate. in addition, adversaries often have the potential to initiate attacks from nearly any location in the world. while the direct physical destruction may be the most obvious strategy for causing blackouts, cyber-attacks could also disrupt the system, cause blackouts, and in some cases, result in physical damage to key system components. as a result, cyber security is just as important as physical security and according to the abovementioned facts, special attention should be paid to this subject. . solutions the previous section provides a brief description of the most challenging issues which are faced by the electricity industry intending to achieve a resilient and sustainable system. this section gives the most e�ective solutions which have been proposed by power industry scientists and engineers. the solutions are asset management, renewable energy resources, de- mand response, controlled islanding and micro-grids, advanced automation systems, self-healing systems, and monitoring systems. . . asset management power systems are constituted by a large number of components which are subjected to di�erent types of tensions ranging from corrosion, fatigue, and severe weather conditions to natural disasters and terrorist attacks. the resistance of the components against the tensions and their capacity to endure extreme conditions directly a�ect overall resiliency and sustain- ability of the power systems. therefore, enhancing components ability to tolerate harsh conditions is a way to move toward a more resilient and sustainable power system. however, managing a large number of highly scattered components that have di�erent types, m. fotuhi-firuzabad et al./scientia iranica, transactions a: civil engineering ( ) { ages, manufacturers, priorities, physical conditions, and required maintenance procedures is a challenging task. asset management is the knowledge that strives to propel capabilities of the physical assets toward desired goals while observing technical and �nancial restrictions [ ]. recent practices of asset management in di�erent industries and also in power systems have proved that asset management techniques are e�ective approaches that can greatly in
uence the system re- siliency and sustainability while coping with limited budget and resources [ ]. in asset management, service provider system- atically looks to �nd the best strategies to acquire, upgrade, operate, maintain, and also dispose assets. it is worthwhile to mention that the best strategies have the ability to satisfy benchmarked resiliency and sustainability indices while meeting budget restrictions. the �rst step of asset management is to develop a few strategic plans for the service provider consider- ing consumer needs, legislations, investors, and the business environment. then, the risk associated with the developed strategic plans is assessed by taking available assets and scheduled asset-related procedures into account. thereafter, �nal decision making is done based on the risks, organizational objectives, and available resources to determine physical asset-related strategies (i.e., acquisition, operation, maintenance, and disposal). . . renewable energy resources as discussed earlier, energy crisis and environmental issues, nowadays, have been considered among the major concerns of humankind around the world. the �rst oil crisis in the early s was a wake-up call for human societies about the limited sources of fossil fuels and as a consequence, the need for sustainable sources of energy. to handle the issue, a few ideas have been proposed, among which were applying new technologies with higher e�ciencies as well as moving toward the so-called `clean energies' as promising alternatives for fossil fuels. development and presence of renewable energies in energy markets can bring diversity to energy consumption and play a role in supplying energy services in a more sustainable manner. on the other hand, all the traditional energy sources pollute the environment while renewable energies are pollution-free and without negative e�ect. the most popular and accepted technologies of renewable energies are wind energy, solar energy (di- rect, photovoltaic, and thermal), hydraulic (employing potential and kinetic energy of water), geothermal, bio-energy, etc. [ ]. based on the data published around the world, it is estimated that renewable energies supplied . % of the total primary energy ( ej) in [ ]. in addition, the contribution of renewable energies was almost % of global electricity supply in . although the share of the energies is still relatively small, their capacities are growing rapidly. in , total installed renewable power capacity worldwide exceeded , gw. this means, in , renewable energies comprised more than % of global generating capacity and supplied an estimated . % of global electricity demand [ ]. renewable energy sources are usually available everywhere in the world. furthermore, technologies which can harness these energies are also available and are improving rapidly. therefore, they can play an important role in stepping toward a sustainable and resilient power system from the following aspects: � social and economic development: the economic development of a society is mainly correlated with per capita energy use. therefore, one can come to this conclusion that electricity services with a higher quality are prerequisites of development. in this re- gard, renewable energies, taking their decentralized nature into account, can improve electricity service sustainability and resiliency in far and especially rural areas and as a consequence, play an important role in fostering rural developments; � energy access: in , more than . billion people had no access to electricity. in addition, it has been forecasted that almost . billion people will request for electricity by . as renewable energies are dispersed around the world, they can be a proper candidate for supplying the upcoming demand of energy. in particular, in rural regions, reliance on renewable energies will allow to attain univer- sal access to modern energy services. the small size of renewable-based units such as photovoltaic, hydropower, and bio-energy can often meet the energy needs of rural regions more cheaply than conventional distributed generation technologies; � climate change mitigation and environmental con- cerns: as a key driving force, climate change mitigation can be achieved by growing the usage of renewable energies. in addition to decreasing greenhouse gas emissions, renewable energies also o�er bene�ts with respect to air pollutions; � energy crisis concerns: proliferation of renewable energy sources in power systems can alleviate de- pendence of the power industry on foreign fossil fuel markets, thereby mitigating energy crisis concerns. . . demand response in the past, power system planners were responsible to predict future electricity consumption and make optimal reinforcement plans in order to serve the load. in such a way, the system was equipped with no driving force to motivate/force consumers to react in response to what was happening in the power industry. having no active role in the power industry, consumers were m. fotuhi-firuzabad et al./scientia iranica, transactions a: civil engineering ( ) { passive players who plugged in their electric devices, consume electricity, and pay bills. however, in recent decades, power industry researchers have understood the value of demand response programs and the signif- icant opportunity they o�er to enhance sustainability and resiliency of the system while decreasing costs. they have found out that even a small portion of demand, which is 
exible, can be an e�ective remedy to mitigate/alleviate the negative impact of several tech- nical and �nancial issues. demand response is referred to any voluntary e�ort to change normal consumption pattern with the objective of individual and/or social bene�ts. demand response can be invoked when either power system resiliency and sustainability is jeopar- dized or electricity procurement cost is substantially raised. as found by engineers, a great portion of power industry issues can be mitigated by demand response potentials. for instance, a faint increment in electricity demand during peak periods might be translated into a signi�cant increase in electricity procurement costs. demand response can be used to decrease the peak load and thus, the procurement cost. moreover, due to severe peak loads, a signi�cant portion of power system facilities are installed to be utilized in a limited number of hours a year. this surely imposes signi�cant monetary losses on the power industry. demand response can be used to 
atten the system load pro�le, therefore postponing a large number of power system reinforcements. also, any unexpected outage in key generation or transmission system components during peak periods may impose signi�cant risks on power sys- tem resiliency and sustainability. in such a situation, demand response, by reducing load, can increase safety margins of the system, thereby propelling it toward a more resilient and sustainable system. in order to realize demand response potentials in a power system, there exist some approaches which can be grouped into two categories. these two categories are price based and incentive based programs. in a price based program, electricity service provider releases time-varying electricity prices, by which con- sumers are motivated to alter their normal consump- tion pattern such that some savings in electricity bills are obtained and power system sustainability is enhanced. in an incentive based program, however, a contract is signed between consumers and the service provider. the contract obliges the consumers to modify their consumption pattern upon receiving a signal from the service provider in exchange for some prede�ned monetary incentives. . . controlled islanding and micro-grid as mentioned heretofore, power systems have been faced with catastrophic events such as the aug. , blackout [ ]. the power industry, in order to pre- vent such events, needs to develop new infrastructures figure . an extra-large power system constituting four sub-systems. and operational concepts. a recently developed oper- ational concept is controlled islanding. the main idea behind the concept of controlled islanding goes back to preventing propagation of faults through the whole system. in controlled islanding, the power system is divided into a few sub-systems which are able to be operated autonomously. the sub-systems are capable to be operated autonomously if they are connected to each other via weak boundary lines and active and reactive power balance conditions are met within each of the sub-systems. according to the concept, following a severe fault in a sub-system, boundary lines are mandatorily opened and healthy sub-systems will be operated autonomously. figure [ ] shows an example of an extra-large power system which consists of four sub-systems. as can be seen, the sub-systems are connected to each other via three tie-lines. besides the concept of controlled islanding, which focuses on sub-systems in the transmission level, the concept of microgrid is another recently proposed idea, which focuses on sub-systems in the distribution level. microgrid refers to a group of interconnected loads and generation units constituting a subsystem [ ]. in fact, a microgrid can be considered as a very small vertically integrated electric utility in which there is no transmission component. in other words, genera- tion and distribution components are the fundamental elements of a microgrid. a microgrid can operate in both grid-connected and islanding modes, since it has the ability to independently serve its loads with the power generated by its generation units. thanks to this capability, following an event in the main grid, a microgrid can disconnect its loads and generation units from the grid and continue to serve its loads with the m. fotuhi-firuzabad et al./scientia iranica, transactions a: civil engineering ( ) { power generated by local generation. consequently, microgrids, by serving loads even when the main grid is de-energized, have the potential to e�ectively improve resiliency and sustainability of power systems. besides, they are equipped by additional control facilities which allow more distributed energy units to be connected to distribution networks, thereby alleviating environmen- tal concerns and energy crisis issues. . . advanced automation power system automation is an e�ective tool by which system operators can promptly react in response to any unexpected event. in [ ], advanced distribution au- tomation is described as the \heart of the smart power delivery system". automation will play a central role in providing enhanced levels of security, quality, reliability, and availability that are characteristics of a resilient and sustainable power system. advanced automation systems are concerned with complete au- tomation of all the controllable equipment and func- tions in the distribution level to improve distribution system strategic operation. the growing and changing role of electricity in our society, availability and need to use distributed generation resources, and the growing importance of service resiliency and sustainability are all drivers of advanced automation systems. the potential bene�ts of an advanced automation system include: � improved reliability and performance of distribution systems; � reduced operating costs; � enhanced contingency responses; � improved power quality; � increased customer service options; � prevention and mitigation of outages; � aid in outage recovery operations; � supporting integration of distributed energy re- sources into distribution operations; � making customer systems a part of the system performance equation. . . advanced monitoring systems monitoring systems provide power system control cen- ters with an insight into current status of the system. based on the system status, the online security analysis of power systems is performed in power system control centers to help system operators in operating power systems in a more resilient and sustainable manner. in recent decades, great e�orts have been devoted to increasing accuracy of monitoring systems. advanced monitoring systems are the result of the e�orts. in the past, monitoring systems updated status of the system every - seconds while advanced monitoring systems update the system status several times a second. measurements of conventional monitoring systems were asynchronous, which resulted in inaccuracies. however, measurements of advanced monitoring systems are equipped with an accurate time tagging system (which is based on the global positioning system) and as a result, their resulted system insight is much more accurate. the more accurate the insight into the system status, which can be obtained using advanced mon- itoring systems, the more the bene�ts to resiliency and sustainability of power systems. accurate sys- tem insight enables operators to more e�ectively take both preventive and corrective actions in the case of likely unexpected events. as noted earlier, e�cient and secure communications are the prerequisites of an e�cient monitoring infrastructure. cyber-attacks may block or delay the delivery of the associated messages or even modify or falsify their contents. in this regard, strict authentication and authorization procedures should be implemented in the monitoring systems to ensure their security and dependability. . . self-healing traditionally, following an event, power system op- erators were informed about service interruptions by calls from a�ected consumers complaining about the curtailed supply. upon receiving an interruption call, system operators by looking at the network topology and protection system settings approximately deter- mined the interrupted area. then, after the rough detection and localization of the interruption causes, a repair crew team was sent to patrol the area and manually �x the problem. however, this manual problem diagnosing and repairing process might take a long time, which could be translated into much more signi�cant monetary losses and dissatisfaction of customers. in order to solve the issue, the idea of self- healing systems was proposed by power industry re- searchers. a self-healing system is expected to respond to threats, material failures, and other destabilizing in
uences by preventing or containing the spread of disturbances [ ]. in a self-healing system, thanks to monitoring and control technologies, system operators are informed about unexpected events by monitoring of network switches status. any sudden change in status of network switches can be a signal of an event. then, following the event detection, available remedial activities are utilized to restore electricity services to the interrupted customers. a self-healing system has to provide non-stop services in terms of: � providing situational awareness throughout the sys- tem; � predicting, preventing, and containing problems; � enforcing operational plans and required margins; m. fotuhi-firuzabad et al./scientia iranica, transactions a: civil engineering ( ) { � supporting system restoration. in order to realize a self-healing system, a high- performance it infrastructure is needed to address gaps in the geographical and temporal coordination of power system monitoring and control. it is also essential to address a comprehensive set of operating concerns (in normal and abnormal conditions) that are associated with performance enhancement, adequacy of resources, and equipment and system operating limits, as well as primary and back-up protection of systems and components. in a self-healing system, not only the existing online analytical capabilities are envisioned to continue playing their role, but also the current o�ine capabilities must be integrated into the online environment. all these surely require the use of online decision support tools with intensive computational and communication requirements. . summary this paper focused on the topic of resiliency and sustainability in the electricity industry. in this regard, the most challenging issues encountered by the power industry as well as the most e�ective solutions proposed by the �eld researchers were thoroughly discussed. the challenges are load growth, energy crisis, emissions and climate changes, unexpected events, aging infrastruc- ture, and cyber challenges. the set of solutions in- cludes asset management, renewable energy resources, demand response, controlled islanding and micro-grids, advanced automation systems, self-healing systems, and monitoring systems. it is worthwhile to mention that the solutions are based on the degree of smartness in the system and can generally be categorized into two major groups. the �rst group contains those solutions which are on the basis of new advanced technologies such as monitoring and automation systems. on the other hand, the second group is devoted to solutions which are based on the existing procedures but with more systematic routines and in a more e�ective man- ner. asset management is an example for the second group of solutions. according to the existing literature, an electricity system in which the pointed solutions are realized is referred to a smart grid or grid of the future. this coincidence goes back to the fact that resiliency and sustainability of electricity services were constituted as the main criteria in developing a roadmap for electricity systems in the future. a typical smart grid is shown in figure [ ]. in the following, e�ectiveness of the solutions in the electricity system is brie
y described: � asset management: the system has a large number of elements including wind turbines, photo- voltaic panels, circuit elements, and switches, each of which has a failure rate. as mentioned earlier in this paper, failure rate of a typical component usually increases substantially through the time. in the considered system, the operator addresses the issue using e�ective asset management strategies, by which optimal candidate elements for maintenance or replacement actions are identi�ed. this is a positive step toward achieving a sustainable and resilient system in a cost-e�ective manner; � renewable energy resources: as can be ob- served in figure , the system contains a large number of renewable-based generating units (wind turbines and photovoltaic panels). the green power produced by the units not only alleviates environ- figure . a typical resilient and sustainable electric power system. m. fotuhi-firuzabad et al./scientia iranica, transactions a: civil engineering ( ) { mental concerns, but also reduces dependency of the system on diminishing sources of fossil fuels. these sustainable energy resources can propel the system toward more resiliency and sustainability as well; � demand response: as can be observed in fig- ure , demand response potential of some 
exible loads is activated in the system. operation of the 
exible loads can be postponed to a later time, whenever any violation in operating conditions is experienced. doing so, service interruptions, which were conventionally invoked to alleviate the violations, are avoided and thus, resiliency and sustainability of the system are enhanced; � controlled islanding and micro-grids: the system contains central power plants as the conven- tional way of energy procurement as well as some smaller generating units dispersed almost all over the territory. in three cases (pointed by smaller network loops), a group of loads and generating units have established micro-grids. the micro-grids, although connected to the main grid during the nor- mal condition, can serve their loads autonomously in an isolated manner. this can be counted as a step toward a more sustainable and resilient system since the loads connected to the micro-grids can be supplied even when the main grid experiences supply interruptions; � advanced automation: as can be seen in fig- ure , the system is equipped with a few remote controlled switches embedded in the shown detec- tors. these switches, following an unexpected event, can be used to isolate the faulted area and restore energy supply to likely interrupted loads. owing to the fast switching actions, which are possible thanks to the automatic remote switches, load restoration can be done promptly, thereby improving the system resiliency and sustainability and thus, convenience of customers; � advanced monitoring system: the at-hand smart system is equipped with an advanced mon- itoring system, by which the operators sitting in the control center can trace the current state of the system and predict occurrence probability of any likely event. therefore, the operators can decide about the most appropriate remedial actions, which should be invoked to minimize possible unpleasant e�ects of the events. besides, the system can be operated under lower security margins, which in turn can be translated into a more resilient and sustainable situation even with lower operating costs; � self-healing: as can be seen in figure , a few detectors and switches are embedded in the system. moreover, the system is designed such that loads can be supplied by at least two independent parallel routes. accordingly, once an unexpected event occurs, the faulted area can be detected based on the status of the detectors. then, appropriate switching actions can be performed to isolate the detected area and serve loads from an alternative route. in this system, fault detection and isolation as well as service restoration to a�ected loads can be done automatically in a very short time. self-healing systems with automatic and prompt responses to events can result in a more resilient and sustainable electricity system. references . coa�ee, j. \risk, resilience, and environmentally sus- tainable cities", energy policy, ( ), pp. - ( ). . available from: https://www.iea.org/publications/f- reepublications/publicatio n/keyworld .pdf. . gopalakrishnan, k. and peeta, s., sustainable and resilient critical infrastructure systems, verlag berlin heidelberg, springer ( ). . holling, c.s. \resilience and stability of ecological systems", annu. rev. ecol. syst., , pp. - ( ). . wildavsky, a., searching for safety, transaction pub- lishers, new jersey ( ). . comfort, l.k., shared risk: complex systems in seismic response, pergamon, new york ( ). . analysis center (nisac) report to the u.s. depart- ment of homeland security (september , ). . billinton, r. and fotuhi-firuzabad, m. \a basic framework for generating system operating health analysis", ieee t power syst., ( ), pp. - ( ). . energy information administration \annual energy outlook with projections to ", u.s. de- partment of energy, feb. [online]. available: ftp://tonto.eia.doe.gov/forecasting/ ( ).pdf. . available from: http://www.tavanir.org.ir. . available from: https://www.iea.org/publications /freepublications/publication/keyworld .pdf. . available from: https://www.bp.com/statisticalre- view. . kothari, d.p. and nagrath, i.j. ,modern power system analysis, tata mcgraw-hill education ( ). . kirschen, d. and strbac, g., fundamentals of power system economics, wiley, new york ( ). . contolella, p., farber-deanda, m., greening, l.a. and kim, t., estimates of the value of uninter- rupted service for the mid-west independent system operator paul centolella saic, midwest independent transmission system operator ( ). m. fotuhi-firuzabad et al./scientia iranica, transactions a: civil engineering ( ) { . bruch, m. m�unch, v. alchinger, m. kuhn, m. wey- mann, m. and schmid g. power blackout risks: risk management options emerging risk initiative - position paper, cro forum (nov. ). . waeyenbergh, g. and pintelon, l. \maintenance con- cept development: a case study", int. jour. product. economics, , pp. - ( ). . setr eus, j., identifying critical components for sys- tem reliability in power transmission systems, doc- toral dissertation, sch. elect. eng., kth, stockholm, sweden ( ). . bostan, v., sobor, i., bostan, i., dulgheru, v., sochirean, a. and gheorghe, a.v., resilient energy systems - renewables: wind, solar, hydro, st., ed., springer ( ). . available from: https://www.ren .net/. . ye, z., walling, r., miller, n., du, p. and nelson, k., facility microgrids, national renewable energy laboratory, new york ( ). . vittal v. and heydt, g.t. \the problem of initiating controlled islanding of a large interconnected power system solved as a pareto optimization", ieee pes power system conference and exposition, seatlle wa ( ). . mader, e.d. and king, j. \microgrids in new england technical challenges & opportunities", connecticut light & power ( ). . \investigation of the technical and economic feasibility of micro-grid based power systems", epri technical report , interim report ( ). . amin, m.s. and wollenberg, b. \toward a smart grid", ieee power energy m, ( ), pp. - ( ). . amin, m.s. and wollenberg, b. \toward a smart grid", ieee power energy m, ( ), pp. - ( ). biographies mahmud fotuhi-firuzabad (f' ) received the bs degree from sharif university of technology, tehran, iran, in , the ms degree from tehran univer- sity, tehran, in , and the ms and phd degrees from the university of saskatchewan, saskatoon, sk, canada, in and , respectively, all in electrical engineering. currently, he is a professor in the department of electrical engineering, and president of sharif university of technology. he is a member of the center of excellence in power system management and control. dr. fotuhi-firuzabad serves as an editor of the ieee transactions on smart grid. amir safdarian (s' -m' ) received the bsc degree from tehran university, tehran, iran, in , and the msc and phd degrees from sharif university of technology, tehran, in and , respectively, where he is currently an assistant professor. he is also collaborating with the power systems and high voltage engineering research group, department of electrical engineering and automation, aalto university, espoo, finland. he was a recipient of the ieee power system operation transactions prize paper award. his research interests include power system reliabil- ity and resilience, distribution network operation and planning, and smart grid issues. moein moeini-aghtaie received the msc and phd degrees from sharif university of technology, tehran, iran, in and , respectively, in electrical engineering. he is currently an assistant profes- sor in sharif energy research institute, department of energy, sharif university of technology, tehran, iran. his current research interests include reliability and resilience studies of modern distribution systems, especially in the multi-carrier energy environment, and charging management of plug-in hybrid electric- vehicles (phevs). rahim ghorani received the bsc degree from isfahan university of technology, isfahan, iran, and the msc degree from sharif university of technology in all in electrical engineering. he is currently pursuing the phd degree and is a member of power system reliability laboratory, sharif university of technology. his research interests include power system resiliency and reliability, asset management, and maintenance scheduling. mohammad rastegar received the bsc, msc, and phd degrees from the sharif university of technology, tehran, iran, in , , and , respectively, all in electrical engineering. he joined the school of elec- trical and computer engineering, shiraz university, shiraz, iran, in . his current research interests include modeling home energy management systems, plug-in hybrid electric vehicle operation, and power system reliability and resiliency studies. hossein farzin received the bsc degree (with distinc- tion) in electrical engineering from sharif university of technology, tehran, iran, in , where he is currently pursuing his phd studies. his research interests include smart grid, integration of electric vehicles and renewable energy in distribution systems, microgrids analysis and optimization, cyber security, and power system reliability and resilience. wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ praxis medica - , .cdr ; ( , ) - // original articlesdoi: . /pramed m relationship between acr and other determinants of microalbuminuria in t dm patients correspondent dijana j. miric institute of biochemistry, faculty of medicine pristina (kosovska mitrovica) anri dinan street, bb kosovska mitrovica, serbia snezana.lestarevic@med.pr.ac.rs dijana j. miric , bojana m kisic , dragana puhalo-sladoje , bratislav m. miric , dragisa rasic , ilija m. dragojevic , dragana pavlovic institute of biochemistry, faculty of medicine pristina, kosovska mitrovica, serbia biochemical laboratory, faculty of medicine, university of east sarajevo, foca, bosnia and herzegovina department of informatics, state university of novi pazar, novi pazar, serbia clinics for internal diseases, faculty of medicine pristina, kosovska mitrovica, serbia saŽetak Увод: Код пацијената са типом шећерне болести (Т ДМ) појава микроалбуминурије се сматра раним клничким зна- ком наступајућег обољења бубрега. Микроалбуминурија се најчешће одређује као однос албумина и креатинина у ури- ну (АЦР). Циљ: Циљ ове студије је да уоптребом преломних вредности АЦР-а истражи детерминанте микроалбуминурије код па- цијената са Т ДМ код којих дијагноза дијабетичне нефропатије још увек није постављена. Материјал и методе: Код пацијената са Т ДМ је три пута у току два месеца одређиван АЦР, као и рутинске биохе- мијске анализе, укључујући ту концентрацију гликационог хемоглобина (hba c), мокраћне киселине (СУА), и атеро- гени индекс плазме (АИП). Преломне вредности за АЦР су биле ≤ . mg/mmol за мушкарце, и ≤ . mg/mmol за жене. Као предикторске варијабле за микроалбуминурију узети су: дужина трајања Т ДМ, податак о хипертензији, hba c, брзина гломеруларне филтрације (egfr), АИП и СУА. Резултати: На основу преломних вредности АЦР-а пацијената није имало микроалбуминурију, док је имало миро- албуминурију. У поређењу са групом без микроалбуминурије, група са микроалбуминуријом је имала већу концентра- цију креатинина у урину, албумина у урину, hba c, триглицерида и СУА, а нижу концентрацију ХДЛ-холестерола. Иако је генерално већи број испитаника имао ниже вредности egfr, корелација између logacr и egfr није била authors summary srpski introduction: the occurrence of microalbuminuria in type diabetes mellitus (t dm) patients is regarded as an early clinical sign of incipient kidney damage. microalbuminuria is often evaluated as urinary albumin to urinary creatinine ratio (acr). aim: to assess determinants of microalbuminuria in t dm patients without prior diagnosis of nephropathy using acr cut-off values. materials and methods: acr was measured in a total of t dm patients, during two months in three non-consecutive days, and routine biochemical analyses were performed, including glycated hemoglobin (hba c), serum uric acid (sua), and atherogenic index of plasma (aip). the cut-off values of acr were ≤ . mg/mmol in males, and ≤ . mg/mmol in females. duration of t dm, history of hypertension, hba c, estimated glomerular filtration rate (egfr), aip, and sua were investigated for association with microalbuminuria. results: according to acr patients were considered as non-albuminuric (n= ) and microalbuminuric (n = ). compared to non-albuminuric group, microalbuminuric group had increased urinary creatinine, urinary albumin, hba c, triglycerides and sua, whilst decreased hdl-cholesterol levels. although egfr was generally reduced, the correlation between logacr and egfr was not significant (p > . ). however, the correlation between logacr and loghba c was significant. the multiple logistic regression analysis revealed hba c (t = . ; p = . ) and sua (t = . ; p = . ) as independent predictors of microalbuminuria in t dm patients. conclusion: at acr cut-off values, concentrations of hba c and sua were independent predictors of microalbuminuria in t dm patients not yet diagnosed with nephropathy. keywords: microalbuminuria, t dm, acr, determinants miric.dijana@gmail.com ; ( , ) - // diabetic nephropathy (dn) is a relatively frequent microvascular complication of chronic hyperglycemia in type diabetes mellitus (t dm) patients, characterized by pro- gressive fall of glomerular filtration rate (gfr), hypertension and persistent proteinuria, mainly albuminuria [ , ]. in clinical practice, even a minimally increased urinary albumin excretion is regarded as an early sign of incipient kidney damage, with potential to progress to overt renal disease. given that dn is highly prevalent in both developed and developing countries and is still rising among end-stage renal disease patients [ , ], assessment of urinary albumin excre- tion rate and recognition of associated risk factors of diabe- tic kidney damage are of great importance. microalbuminuria is defined as urinary albumin excre- tion rate within the range of - mg per day, found in two non-consecutive urine samples during three months period [ ]. as urinary albumin excretion rate may be influenced by diurnal variations and other collection issues, urinary albu- min to urinary creatinine concentration ratio (acr) has been introduced for better accuracy [ – ]. on the other hand, the most clinicians prefer to assess kidney function as esti- mated gfr (egfr), a mathematical approximation usually calulated by modification of diet in renal disease (mdrd) study group formula, which includes data regarding age, sex, ethnicity, and serum creatinine. however, serum creatinine levels can be unchanged untill even % of kidney function is lost, thus egfr may not always reliably reflect the degree of kidney damage [ ]. microalbuminuria is also considered as a risk factor for progressive renal impairment. evidences suggest that poor glycemic control, high blood pressure, obesity, and atherogenic dyslipidemia, are the most important risk fac- tors for the development of dn [ , , ]. these risk factors are highly prevalent in adult serbian population [ , ], where . % population is currently diagnosed with diabetes, predominantly with t dm [ ]. even with regular use of anti- diabetic, anti-hypertensive and lipid-lowering drugs, dn would eventually develop in a number of t dm patients. gi- ven that determinants of microalbuminuria may help iden- tifying risk factors for diabetic kidney disease, this study has investigated the relationship between acr and several de- mographical, biochemical and clinical parameters in patie- nts witht dm. study design and participants enrolled were total of patients both sexes previously diagnosed with t dm but with no diagnosis of dn, who attended university health center at foca for diabetes control. patients were on regular anti-diabetic medication for at least years. not included were diabetics with macroalbuminuria (urinary albumin excretion ≥ mg/ day), as well as those previously diagnosed with dn, renal calculosis, recent stroke or myocardial infarction, and with known hepatic, autoimmune or malignant diseases. this stu- dy was conducted in accordance with the declaration of hel- sinki. informed consent was provided from all participants included after careful explanation of the study goals. the institutional review board of faculty of medicine foca has approved this study. data collection data regarding age, duration of diabetes, medication, history of hypertension, smoking habits, and clinically confir- med complications were recorded from patients' files. hy- pertension was defined as having systolic blood pressure ≥ mmhg, or diastolic blood pressure ≥ mmhg, or on antihypertensive medication. body mass index (bmi) was cal- culated at the middle of the study as the ratio of body weight (kg) and square body height (m ), and considered normal if ≤ . kg/m . biochemical measurements for determination of acr, patients provided the first morning urine sample in sterile urine sample containers. samples were provided during two months in three non- consecutive days. venous blood was collected on the occa- sion of urine testing, after an overnight fasting, and taken into tubes with or without anticoagulant. the average values of all three measurements were taken for statistical ana- lyses. concentration of urinary albumin was determined on biochemical analyzer (cobas integra , roche diagnostics) by immunoturbidmetric end-point method using tinaquant albumin gen. assay kit (roche diagnostics gmbh, mannheim, germany). the results were expressed as milli- grams albumin per liter urine (mg/l). concentration of crea- tinine in samples was determined kinetically, according to the method of jaffe. the acr value was calculated for each patient as urinary albumin (mg/l) to urinary creatinine (mmol/l) ratio. the criterion for normal urinary albumin excretion was acr ≤ . mg/mmol in males, and acr ≤ . mg/mmol in females [ ]. estimated glomerular filtration rate (egfr) was calculated according to mdrd formula [ ]. the other biochemical parameters, including serum to- tal proteins, albumin, triglycerides, total cholesterol, hdl- cholesterol, and uric acid (sua) were measured using stan- dard protocols. concentration of glycated hemoglobin a c (hba c) was assessed from anticoagulated blood samples by turbidimetric inhibition immunoassay method. atherogenic index of plasma (aip) was calculated according to dobiasova [ ], as the logarithm of triglycerides to hdl-cholesterol ratio [log (tg/hdl-cholesterol)]. statistical analysis statistical analysis was performed using statistica . software package (statsoft, tulsa, ok, usa). frequency статистички значајна (p > . ), док је коралација између logacr и loghba c била значајна. Мултипла логистичка регресиона анализа је показала да су hba c (t = . ; p = . ) и sua (t = . ; p = . ) независни предиктори микроалбуминурије код пацијената са Т ДМ. Закључак: Код пацијената са Т ДМ код којих дијагноза нефропатије још увек није постављена су концентрације hba c и sua независни предиктори микроалбуминурије. Кључне речи: Микроалбуминурија, Т ДМ, АЦР, детерминанте introduction material and methods // original articles ; ( , ) - distribution and homogeneity of variance was tested by kol- mogorv-smirnov test. data were presented either as ari- thmetic mean ±sd, geometric mean and % confidence in- terval of the mean, or frequencies (n). differences between groups were tested by student's independent samples t-test or chi-square test, where appropriate. for comparisons, geo- metric means were back-transformed. the correlation ana- lysis was accomplished by calculation of spearman's rank coefficient. the relationship between possible determinants and acr was investigated by performing binary logistic re- gression analysis and by means of general regression models. statistically significant finding was considered if p < . . acr values were measured in a total of patients with t dm without previous diagnosis of dn. all were caucasians, males and females, aged . ± . years, with dia- betes duration from to years. the majority of parti- cipants were overweight (bmi: . ± . kg/m ), with slightly reduced egfr ( . ± . ml/min/ . m ), and with average glycemic control of hba c= . mmol/mol ( . – . mmol /mol). complications were previously recorded in pati- ents (chi-square= . ; p= . ), as having one or more of the following: neuropathy (n= ), retinopathy (n= ), angio- pathy (n= ), and maculopathy (n= ). according to accepted criterion for acr reference va- lues [ ], patients were assigned to non-albuminuric (n= ) or microalbuminuric group (n= ). basic demographical, clini- cal and biochemical findings in these groups are presented in table . as expected, concentrations of urinary albumin and acr were significantly higher in microalbuminuric than in non-albuminuric group, irrespective of whether egfr was within the normal range (≥ ml/min/ . m ) or decreased (table ). urinary creatinine excretion was higher in micro- albuminuric group, while serum creatinine levels and egfr did not differ between groups (table ). indices of nutritional status and glycemic control are presented in table . compared to non-albuminuric group, patients with microalbuminuria had lower concentrations of hdl-cholesterol, and higher concentrations of sua, triglyce- results rides and blood hba c. also, aip was higher in microalbumi- nuric than in non-albuminuric group, but the difference did not reach statistical significance (p= . ). the correlation analysis revealed no statistically signi- ficant relationship between egfr and either acr (rho=– . ; p> . ), or urinary albumin concentration (rho= . ; p> . ), while logacr was significantly corre- lated to loghba c (figure ). table . general characteristics of type diabetes mellitus patients according to albuminuria status table . nutritive status and glycemic control in patients with t dm according to albuminuria status figure . relationship between hba c and acr levels in t dm patients. data were logarithmically transformed and presented as linear regression line with % prediction interval table . multivariable logistic regression analysis for association between microalbuminuria and risk factors for incipient kidney damage in t dm patients data are presented either as arithmetic mean ±sd, frequencies (n), or geometric mean and % confidence interval of the mean (in parenthesis). differences between groups were tested by student's independent samples t-test or chi-square test. * p< . vs. normoalbuminuric group data are presented as arithmetic mean ± sd, or geometric mean and % confidence interval of the mean (in parenthesis). differences between groups were tested by student's independent samples t-test. * p < . vs. non-albuminuric group by performing logistic regression analysis we further investigated relationships between microalbuminuria (yes vs. no), defined according to accepted acr cut-off values [ ], and some possible risk factors for diabetic kidney injury. the duration of diabetes, egfr, a history of hypertension (yes vs. no), aip, sua and blood hba c concentrations were considered as predictor variables. the multivariate logistic regression analysis revealed hba c (t= . ; p= . ) and sua (t= . ; p= . ) as stati- stically significant independent predictors of microalbumi- nuria in t dm patients (table ). ; ( , ) - // discussion in the current study, the occurrence of microalbuminu- ria was independently associated with both high blood hba c and sua levels, confirming that diabetic kidney injury is prin- cipally due to chronically poor glycemic control [ , , ]. gi- ven that sua is also considered as a biomarker of endothelial dysfunction [ ], these results suggest involvement of hyperglycemia-associated endothelial dysfunction in the de- velopment of diabetic renal complications. however, acr va- lues were poorly correlated to egfr, which is the most pre- ferable clinical tool for assessment of kidney function. glycemic control is usually assessed by measuring hba c level, although many other proteins, such as serum albumin, more readily undergo glycation process. it has been shown that, compared to hemoglobin molecule, glucose binds to serum albumin with times greater affinity, resulting that in chronic hyperglycemia up to % albumin molecules are at glycated form [ ]. indeed, concentration of glycated serum albumin highly corresponds to hba c levels in the absence of anemia [ ]. serum proteins are usually present in tissues, where can play important roles by maintaining cell viability, but can also induce serious tissue damage. serum albumin, for example, if present at low concentrations, supports the survival of proximal epithelial tubular cells and macrophages [ ]. however, at higher concentrations albumin can induce pro-inflammatory and profibrotic response, either acting as an inhibitor of podocyte insulin-dependent antiinflammatory angiotensin-converting enzyme- , or by sensitizing tubular cells to potentially toxic compounds transported by albumin [ , ]. glycated albumin was shown to be even more nephrotoxic since it induces interstitial fibrosis at very low concentration [ ]. in established microalbuminuria both gly- cated and unmodified albumin molecules are expected to be present in ultrafiltrate at supraphysiological levels. since these molecules are nephrotoxic per se and are present at hi- gh levels in ultrafiltrate, they can further exaggerate tissue injury leading to overt kidney damage. still, microalbuminu- ria may not always progress to macroalbuminuria but may re- gress, instead, [ ], pointing that multiple factors can be im- plicated in the development and progression of diabetic kidney injury. in previous studies sua levels above the normal range were linked to vascular complications of t dm [ , ]. in the current study, sua was independently associated with microalbuminuria. however, in the current study sua con- centrations were within the normal range in the most parti- cipants, although in microalbuminuric group tended to di- stribute mostly within the upper reference limits of the me- thod. recently, these high-normal values of sua were sugge- sted to predict the annual decline of egfr and the develo- pment of chronic kidney disease among t dm patients with relatively preserved kidney function [ ]. uric acid is a de- gradation product of purine catabolism, extensively formed in cells under hypoxic conditions. it is now accepted that beside of being a marker of cellular energy crisis, sua can be both a mediator and a biomarker of generalized endothelial dysfunction, inflammation and vascular disease [ ]. although atherosclerosis and hypertension exacerbate cellular energy crisis, we observed only a weak association between microalbuminuria and the history of hypertension (table , figure ). it has to be noted that data regarding hypertension were collected as qualitative, from medical records, and therefore must be cautiously interpreted. it was reported that microalbuminuria was associated with systolic rather than diastolic blood pressure or pulse pre- ssure, representing an indicator of hemodynamic distur- bances [ ]. hypertension is highly prevalent among serbian population and in republic of srpska [ ], which is the pro- bable reason why the proportion of patients with history of hypertension was similar in both non-albuminuric and albu- minuric groups in the study. also, the most of hypertensive patients were treated with ace inhibitors (data not presen- ted), previously reported to postpone the onset of micro- albuminuria in hypertensive t dm patients [ ]. ace inhi- bitors were also demonstrated to restore megalin expression in proximal tubular cells, and normalize albumin tubular rea- bsorption, thereby reversing microalbuminuria in sterpto- zotocin diabetic rats [ ]. association between microalbuminuria and aip, as a su- rrogate marker of atherogenic dyslipidemia [ ], was also weak in our study. atherogenic dyslipidemia, characterized by increased plasma triglycerides, decreased hdl-chole- sterol and altered composition of ldl-cholesterol, is a well- known risk factor for the development and progression of diabetic nephropathy [ , ]. recently, one meta-analysis study reported that aip can predict the risk of t dm in gene- ral population [ ], and there was a significant association between aip and microalbuminuria in non-diabetic patients with essential hypertension [ ]. also, acr and hdl-chole- sterol were poorly correlated (rho = – . ; p = . ), and in accordance to one previous report [ ]. the results of the current study indicate that major de- terminants of microalbuminuria in t dm patients were increased blood hba c and sua levels. it has to be noted that we assessed microalbuminuria as acr values. still, recent studies suggest that reliability of acr for assessment of kidney function can be sometimes questionable [ – ]. na- mely, acr may underestimate cases with slightly increased urinary albumin excretion and concomitantly increased uri- nary creatinine excretion, such as in male diabetics with gre- ater muscle mass [ ], and in diabetics with preserved renal compensatory mechanisms [ ]. to corroborate, we observed that serum creatinine levels were within the normal range whilst urinary creatinine levels were higher in microal- buminuria (table ), suggesting that renal adaptive mecha- nisms were still operational in a number of patients with in- creased acr. also, there was a relatively weak correlation between acr and egfr, despite the fact that the majority of participants with microalbuminuria ( . %) were with mildly or moderately reduced egfr. this is in accordance to some previous studies who found that approximately one third t dm patients with mild and % with moderate renal impa- irment may have normal acr values [ , ], and that acr levels do parallel egfr mostly in macroalbuminuria [ ]. to conclude, blood hba c and serum ua levels were significant determinants of microalbuminuria, suggesting that a long-lasting hyperglycemia and endothelial dysfun- ction synergistically contribute to diabetic kidney compli- cations in t dm patients. given that increased urinary albu- min excretion rate can be considered not only as a marker but also as a mediator of kidney damage, and that the occu- rrence and the degree of albuminuria may not always para- llel the reduction of kidney function, we suggest that the surveillance of kidney damage in t dm should be based on both acr and egfr determinations. conflict of ineterst the authors declare no financial or other conflict of interest regarding this manuscript. ; ( , ) - // original articles . toyama t, furuichi k, ninomiya t, shimizu m, hara a, iwata y, et al. the impacts of albuminuria and low egfr on the risk of cardiovascular death, all-cause mortality, and renal events in diabetic patients: meta-analysis. plosone ; ( ): e . 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(https://doi.org/ . /srep ) critical care december vol no leverve abstract lactate, indispensable substrate of mammalian intermediary metabolism, allows shuttling of carbons and reducing power between cells and organs at a high turnover rate. lactate is, therefore, not deleterious, although an increase in its concentration is often a sensitive sign of alteration in energy homeostasis, a rise in it being frequently related to poor prognosis. such an increase, however, actually signifies an attempt by the body to cope with a new energy status. hyperlactatemia, therefore, most often represents an adaptive response to an acute energy disorder. investigation of lactate metabolism at the bedside is limited to the determination of its concentration. lactate metabolism and acid- base homeostasis are both closely linked to cellular energy metabolism, acidosis being potentially a cause or a consequence of cellular energy deficit. lactate is certainly not a pyromaniac: it is not toxic and possesses no harmful effect per se. it is probably a trustworthy sentinel because it sensitively indicates that fire is potentially in the house and numerous works have already shown a good relationship between lactate level and outcome [ ]. above all, it is an indispensable soldier that actively acts as a major intermediate involved in the vast cellular and organ energy interplay, allowing the body to cope with a wide range of metabolic disorders (for example, exercise, hypoxia, ischemia, severe sepsis, shock) [ ]. based on their broad experience in the management of the profound metabolic derangements observed in critical illnesses, associated with some experimental data, valenza et al. [ ] propose, in a review-hypothesis paper in this issue of critical care, to regard lactate increase in the intensive care unit as a marker of a metabolic adaptation requiring a therapeutic aid (“possibly indicating that ‘there is still room’ to boost fast intervention”) rather than a sign of irreversible end- stage energy failure. in this context, these authors propose to take the decrease in blood lactate following a therapeutic challenge as a major indicator of the efficacy of such treatment. this proposal seems absolutely correct and very close to what has been already proposed regarding oxygen consumption (vo ), but with a simple bedside parameter of metabolic integration. indeed, whatever the cause of derangement and the metabolic environment, any rise in blood lactate indicates an attempt by the body to adapt to an unusual energetic situation, which may affect redox state, phosphate potential or ph [ ]. moreover, as indicated by the authors, lactate production requires a complete glycolytic pathway, that is, an intact cell with sufficient glucose supply or glycogen storage. therefore, in ischemic tissues, which don’t have a sustained supply of blood glucose, a substantial amount of lactate can be released as long as glucose is present in the interstitial fluid or in the cells (glycogen). thus, it should be noted that a decrease in lactate might imply ‘a correction’ of the initial disorder but also an exhaustion of the precursor (glucose) or a destruction of tissues. in fact, as for any metabolite, lactate concentration depends on the ratio between production and consumption. because these two parameters are not routinely assessed at the bedside, however, the pathophysiological view is mostly based on lactate concentration only, which may represent a sometimes hazardous shortcut. lactate metabolism is intimately linked to the three major potentials of living systems, all strictly related to energy metabolism: redox potential ((nadh, h+)/nad+); phosphate potential (atp/ (adp × pi)); and hydrogen potential or ph ( . + log(hco -/ . × paco )). the first indicates a potential deficit in oxidation (oxygen or oxidative capacity), the second shortage in energy and the third, which is closely linked to these parameters, could be viewed as a metabolic tool allowing the exact matching between them. atp turnover is controlled by ph [ - ]: acidosis decreases atp turnover and oxygen demand, representing an adapted or deleterious event depending on how deep, how long and how reversible. commentary lactate in the intensive care unit: pyromaniac, sentinel or fireman? xavier m leverve professor and director of the research unit, inserm-e ‘bioénergétique fondamentale et appliquée’, université j fourier, grenoble, france corresponding author: xavier leverve, xavier.leverve@ujf-grenoble.fr published online: november critical care , : - (doi . /cc ) this article is online at http://ccforum.com/content/ / / © biomed central ltd see related review by valenza et al. in this issue, page [http://ccforum.com/content/ / / ] available online http://ccforum.com/content/ / / although there is no doubt about the fact that a change in lactate metabolism is linked to energy imbalance, the complete picture of the mechanisms involved in lactate regulation, which represents just a piece of a very complex puzzle, triggering or inducing an adaptive response is not completely clear as yet. however, anaerobic atp supply from a glycolytic anaerobic source is limited in terms of its sustained rate of atp production, except for a very acute and short muscle contraction. as a matter of fact, ml/minute oxygen consumption (vo = . mmol o ) represents an atp turnover of approximately mmol/minute, which costs about . mmol/minute ( . g) of glucose when oxidized and mmol/minute ( . g) when metabolized anaerobically. hence, the entirety of liver glycogen would be consumed in about minutes as there is no glucose release from glycogen in muscle cells because of the lack of glucose- phosphatase. with the exception of initial muscle contraction, increased anaerobic glycolytic atp production is adaptive for a fall in mitochondrial (aerobic) atp supply only when associated with a decrease in atp consumption, imposing a new hierarchical setting on the different atp consuming pathways. in other words, lactate-associated (anaerobic) atp production is an appropriate response to ischemia, anoxia or any kind of energy crisis only when the body can simultaneously save energy. the consequences of these changes in cell priorities represent a major aspect of understanding metabolic derangement in acute organ failure. acidosis is linked to energy metabolism and lactate homeostasis is related to both ph and energy status. when metabolic or respiratory acidosis is the initial event, it depresses energy expenditure and lactate might rise, but only modestly. correction of acidosis improves the energetic derangement. in contrast, when the primary defect concerns energy homeostasis, ph decrease is adaptive: lowering energy expenditure allows matching a decrease in oxidative atp synthesis capacity and the rise in lactate concentration and turnover is part of this adaptation. it should also be considered that rises in lactate also occur frequently in the absence of acidosis, or even simultaneously with alkalosis. indeed, several causes of hyperlactatemia encountered in intensive care unit patients appear to be independent of any defect in cellular energy status [ , ]. in these situations, the significance and prognostic value of such hyperlactatemia are very different from those associated with acidosis. in conclusion, the significance of hyperlactatemia depends on the concomitant acid-base status because of a common link with energy metabolism. when acidosis is the primary cause of the metabolic abnormalities, cellular energy deficit is a consequence, lactate rise is modest and correction of ph improves the metabolic disorder. when the cellular energy defect is the primum movens, hyperlactatemia and acidosis are its consequences and ph correction without simultaneous improvement of the energy defect impairs the adaptive response to energy failure, as represented by acidosis. when lactate increases in the absence of acidosis, it probably indicates a lack of a relationship with energy deficit. competing interests the author(s) declare that they have no competing interests. references . bakker j, coffernils m, leon m, gris p, vincent jl: blood lactate levels are superior to oxygen-derived variables in predicting outcome in human septic shock. chest , : - . . leverve xm, mustafa i: lactate: a key metabolite in the inter- cellular metabolic interplay. crit care , : - . . valenza f, aletti g, fossali t, chevallard g, sacconi f, irace m, gattinoni l: lactate as a marker of energy failure in critically ill patients: hypothesis. crit care , : - . . leverve xm: energy metabolism in critically ill patients: lactate is a major oxidizable substrate. curr opin clin nutr metab care , : - . . sutton jr, jones nl, toews cj: effect of ph on muscle glycoly- sis during exercise. clin sci (lond) , : - . . ehrsam re, heigenhauser gj, jones nl: effect of respiratory acidosis on metabolism in exercise. j appl physiol , : - . . bulbulian r, girandola rn, wiswell ra: the effect of nh cl induced chronic metabolic acidosis on work capacity in man. eur j appl physiol occup physiol , : - . . kowalchuk jm, heigenhauser gj, jones nl: effect of ph on metabolic and cardiorespiratory responses during progres- sive exercise. j appl physiol , : - . . barclay jk, graham te, wolfe br, van dijk j, wilson ba: effect of acidosis on skeletal muscle metabolism with and without propranolol. can j physiol pharmacol , : - . . bharma s, milsom wk: acidosis and metabolic rate in golden mantled ground squirrels (spermophilus lateralis). respir physiol , : - . . hotchkiss rs, karl ie: reevaluation of the role of cellular hypoxia and bioenergetic failure in sepsis. j am med assoc , : - . . levy b, gibot s, franck p, cravoisy a, bollaert pe: relation between muscle na+k+ atpase activity and raised lactate concentrations in septic shock: a prospective study. lancet , : - . 	abstract 	competing interests 	references --------------- --------------------- - - -- appreciation the life and work of bill heronemus, wind engineering pioneer by woody stoddard reprinted from wind engineering volume , no. , multi-science publishing company wares way · brentwood · essex cm tb · uk tel: + ( ) · fax: + ( ) e-mail: mscience@globalnet.co.uk . web site: www,multi-science.co.uk mailto:mscience@globalnet.co.uk wind engineering volume , no. , pp - the life and work of bill heronemus, wind engineering pioneer woody stoddard ocean wind energy systems, po box ,amherst ma usa. email <woodystodd@aol.com> abstract william edward. heronemus, captain,. usn (ret.), professor eme~ihls, university of massachusetts at amherst, born april , , died november , : this is a memorial record and obituary of a remarkable wind power engineer, bili heronemusof the university of massachusetts and, previously, of the us navy. the author, a previous student and close colleague, writes personally, with much input .and support from other colleagues and previous students. the aim is not only to record research, development and commitment at the early stages of modern wind power, but also to honour an admirable pioneer. bill heronemus is credited with foreseeing the oil crisis and thereafter wind power developments that have since been realised, including offshore wind farms. he is also credited with teaching and motivating many students who later became professional of modern wind power development and commerce. the obituary note has been written from personal knowledge and from many written and verbal communications from colleagues and friends of bill heronemus who worked with him at different stages of his life. details are referenced, with other records kept with the author. i. introduction bill heronemus is known the world over as the "father of modern windpower" and the inventor of the wind turbine array, windship, wind furnace and offshore hydrogen flotilla ideas. he is generally credited with the invention of the terms "windfarm", "windshaft" and "windsmith" in wide use today. all the present researchers in wind turbines owe the grasp of the fundamentals to bill heronemus' work of the s, when he and his cadre published many, many reports on windpower, along with the earlier pioneers forming the backbone of all the engineering, which was yet to come. wind turbine engineers the world over know of bill's work, and quietly credit him with the original plan and vision, because most of us knew that he steadfastly avoided any public adulation or praise for his work, which he considered just to be "plain old common sense". bill heronemus was an engineer's engineer. he was humble, and would have been horrified and embarrassed to see his life in print like this. but he gave us a vision and a legacy for our own dreams, and changed many lives. . a summary of the work of bill heron emus the exert below was written in by bill heronemus as professor of civil engineering at the university of massachusetts in amherst [ ]: "in the immediate future, we can expect the 'energy gap' to result in a series of crises as peak loads are not met. the east coast will be dependent on foreign sources for most of its oil and gas. the environment will continue to deteriorate in spite of ever-increasing severity of controls. air pollution, oil spills and the life and work of bill heronemus, wind engineering pioneer thermal pollution are likely to be worse, not better in . in the face of the continuing dilemma: power us. pollution: a third alternative [to nuclear and fossil energy} must be sought. it may be found in the many and varied non­ polluting energy sources known to exist in the us or its offshore aggregate. these energy sources, tied together in a national network, could satisfy a significant fraction of our total power needs in the year ': thus bill heronemus not only predicted the worldwide energy difficulties which were to come, including nuclear power plant failures, but saw the grand scale of future of renewable energy development [ ]. this included solar thermal, land-based and offshore wind [ ], and ocean thermal energy. he had encyclopaedic knowledge of power plants, oceanography and engineering, and he was able to present his arguments in a practical and convincing way. originally from a dairy farming family in lancaster, wisconsin, bill heronemus attended the us naval academy at annapolis, and was commissioned ensign, usn, on december , . he was immediately assigned as gunnery officer on the destroyer uss woodworth, and fought in the campaigns in the solomon sea and western pacific, where he was awarded the bronze star with combat 'v' for his actions under fire. later in the war and being an engineer, l . heronemus was reassigned to the famous battleship uss north carolina in february as the engineering auxiliary officer. after the war, he attended mit to complete his ms in naval architecture & marine engineering; his chief interest was the propulsion of warships and submarines. at the portsmouth naval yard in , he became a submarine engineering duty officer, and he spent the next years in the us navy working on the design and construction of the us nuclear submarine fleet. he was a central figure in the unprecedented cold war effort to establish a formidable us nuclear submarine fleet under three presidents, which was pivotal in maintaining detente. in , bill heronemus became the assistant naval attache to the court of s . james in london, england. bill retired from active duty at the rank of captain in , and went to united aircraft corporation as the engineering manager, still pursuing power systems. in , bill took the job of starting an ocean engineering department at the university of massachusetts. the oe work included oceanography, marine biology and geology as well as naval architecture, which bill taught personally in a very difficult two-semester course. we were lucky to have had him for a teacher and mentor. in the late s bill heronemus correctly predicted a coming energy crisis, and began a national debate on energy policy, advancing the use of "grand scale renewables" to replace gradually fossil fuel and nuclear energy. bill was already an expert on structures, power systems and the oceans, and quickly learned ocean thermal and wind energy by using the literature available in the s, the work of the other pioneers: juul, champly, hutter, betz, percy thomas, golding, shefter, lacroix, helge petersen, sabinin, vadot, stodhart, putnam, lecours, honnef, claude, chilcott, and many others. to their work, he added support structures for multiple arrays (fig ), wind ships, flotillas and a hydrogen storage system to firm the power. he enlisted practically the entire engineering faculty of umass, and presented a landmark proposal urging the national science foundation in to accelerate renewables research and development [ ]. the proposal was audacious, including putting many wind turbines on a space array, on wind ships out at sea in flotillas, to harvest the wind energy there producing hydrogen fuel and anhydrous ammonia fertilizer via electrolysis. the grand scale offshore wind power system was showcased in the december issue of national geographic magazine. it depicted a -turbine array wind ship moored at sea in a flotilla, converting seawater to hydrogen fuel. this concept was widely circulated in the technical wind engineering volume , no. , and popular press, but no funding came to umass because the competing interests were too strong. the offshore windpower concept was eagerly adopted by the energy research and development administration (later the us department of energy), who funded ge and westinghouse, using bill's ideas. their results were mediocre, and seemed to discredit offshore windpower, but our technological culture is very close to realizing that vision now. bill's energy debate grew, with his appearances before congress and many government agencies and utilities, each time presenting feasible plans for renewable energy [ , , , , , , , is, , ]. this culminated in the carter administration recognizing the wisdom of the plan, and in with umass getting a contract with nsf to design and construct the wind furnace and solar habitat, a m wind turbine heating a single-family solar home via large hot water storage tanks (northeast utilities would not permit us to produce grid electricity). the wf-i was commissioned on nov. , . the installation, though idle, still stands on the umass campus, and is a well-known landmark to all of us who studied wind energy then. -' {~. ~ #" ...,;'-­ if figure 	 design for a multiple-array wind turbine structure, produced by bill heronemus and his colleagues at the university of massachusetts in the early s. the concept predicted offshore windfarms. the turbines on this array were based on the russian yalta machine of the s, as described in the classic book by golding (reprinted ) the life and work of bill heronemus, wind engineering pioneer in , bill founded the wind power group in the umass engineering department. bill personally enlisted other professors from mechanical, electrical, and civil engineering to lend their leadership and expertise to the program, notably, jon mcgowan, dick monopoli, duane cromack, bob kirchhoff, frank kaminsky, al russell and merit white. this team of professors generated a group of undergraduate and graduate students to work in renewable energy under bill. the major efforts were offshore windpower and ocean thermal energy. since we were all eagerly learning about wind turbines, bill and the author gave the first course in windpower engineering to the students in . under jim manwell's leadership this course has continued as an official umass engineering course of study, unbroken ever since then, culminating with a conlprehensive textbook [ ] this umass renewable energy project was long-lived, due to bill's consistent lobbying and pushing the doe to implement solar, wind, and ocean thermal energy. the graduates from the windpower course numbered in . these were the students who designed and built the wind furnace. in subsequent years, the number of students grew, and this cadre of graduates formed the core of the us wind industry, both in founding wind energy companies and staffing the national agencies, principally nrel (national renewable energy laboratory). dozens of bill's students still work in the wind industry and doe, and the "umass mafia", as it is fondly known, is still the strongest core of close professionals in the field in the world. these umass graduates were, and still are, eagerly sought by the now-large wind turbine companies. during the s, bill worked on ocean thermal energy conversion (otec) [ ]. he proposed large otec plants abroad and in the us, along with wind turbines in appropriate locations, at a yearly cost starting with two billion dollars and increasing over the years. he took leave from the university to start his own company, ocean wind energy systems. co­ operating with the alfa-laval company, the plan was to build a prototype otec. the estimate was that such energy systems should cost no more than current generating plant, but would produce no pollution, no fuel shortages, no price increases and a simple, labour-intensive technology offering more ample and more balanced employment. us windpower was founded by stanley charren and russell wolfe in ; the company became the first major us wind turbine manufacturer. this company undertook to build "windfarms" based on bill's ideas and the original wind furnace design. us windpower (later kenetech) became the largest wind energy firm in the world, and succeeded in erecting thousands of windmills. charren and wolfe credit bill with the vision and plan which "created the entire windpower community", and then "staffing it with his own students and graduates". bill lived to see windpower grow into a major industry and way of life in the world. he particularly enjoyed the offshore windfarms. he pursued his own research and designs through the ' s and ' s, with help from his previous students. in , bill and the author founded ocean wind energy systems, inc. to implement the wind turbine array, windship, wind furnace and hydrogen flotilla and codify bill's vision and designs in patents. bill heronemus was a member of the society of naval architects and marine engineers, asme, american society of naval engineers, international solar energy society (ises), marine technology society, sigma xi, phi eta sigma and the american wind energy association. he was the recipient of the chancellor's medal at umass in , an nsf grantee, - , and awarded the lifetime achievement award by the american wind energy association in : "in recognition of the inspiration that he provided to an entire generation of wind energy engineers and of a vision for the wind industry that is only now starting to be realized". ,in his awea acceptance speech, bill said: wind engineering volume , no. , "there is an absolute requirement for the earth to remain in thermal balance within our solar system. there is only one ultimate solution to the global warming problem: total reliance upon solar energy. and the most productive of all solar energy processes is the wind energy process." he continued, saying, "wind power needs to be developed at a steady and appropriate pace, but the free market capitalistic system that we hold so dear will not do the job. there is need for massive governmental interference. if we wait for the private sector to reduce the greenhouse gases linked to our fossil fuel use, it will be too late." he remained active until the last days of his life, writing in [ ]: "renewable energy is mandatory for the future of mankind. wind energy is one of the best sources, and the technology already exists to tap it. europeans are moving quickly in this direction, while americans are dragging their feet': in conclusion, the following paragraph is taken from a published obituary [ ]: "heronemus' crusade to expand energy sources makes sense to us and is more relevant than ever today, when many people believe the quest for oil is a destabilizing factor in world politics. but ideas such as his found little favour in the us, where "black gold" has always been king. wind power, being less tangible than other energy sources, just doesn't excite the imagination of the energy industry the way a gushing oil well does. the industry's fears of competition also played a part in its rejection of heronemus' ideas. a source of power that is easily obtained, renewable and doesn't require extensive supporting industries - in short, one that upsets the established order and could compromise profits - is viewed as a threat rather than a possible solution to a problem... we don't want to give the impression that william heronemus' struggle to promote alternative energy sources was in vain. far from it; his vision is becoming a reality in denmark, which hopes by to supply % of its electricity through renewable energy sources - a large portion of it from offshore wind turbines. william heronemus is gone, but his ideas live on. they are needed now more than ever, and we'd like to see them given more consideration, especially in the united states. there is little to lose and much to gain". references heronemus we. (april ) a national network of pollution-free energy sources, proposal submitted to the national science foundation, research applied to national needs (rann) directorate, washington dc. heronemus w.e. ( ) the us energy crisis: some proposed gentle solutions, the congressional record, vol. , no. , feb. ; also presented at joint meeting of american society of mechanical engineers and institute of electrical and electronics engineers, springfield ma, jan. , . heronemus we. (april ) a proposed program for the development of wind power in the united states, presented before congressional hearings, washington dc. heronemus we. ( ) power from the offshore winds, proceedings of the th annual conference of the marine technology society, washington, dc. s heronemus w.e. ( ) alternatives to nuclear engineering, catalyst, vol. ii, no. . heronemus we. (jan. ) a proposed two-increment wind power system for the production ofelectricity for long island, prepared for the lloyd harbor study group as testimony for lilco proposed shoreham nuclear power station, aec docket no. - , long island ny 	 the life and work of bill heronemus, wind engineering pioneer 	 heronemus w.e. ( ) energy: windpower in the s, presented at american geophysical union meeting, washington dc, april . 	 heronemus w.e. (june ) the possible role of unconventional energy sources in the - u.s. energy market, testimony presented at hearings before the subcommittee on science, research and development of the committee on science and astronautics, u.s. house of representatives, nd congress, washington dc. 	 heronemus w.e. ( ) a proposal to investigate windpower as a natural, clean, solar­ driven energy resource with potential for significant impact on the united states' energy market, proposal submitted to the national science foundation, washington dc. 	 heronemus w.e. ( ) a preliminary study of a large windpower electricity system sited in the lake ontario region, university of massachusetts report prepared for the oswego ecology action group, oswego ny heronemus we. (sept. , ) windpower: near-term partial solution to the energy crisis, presented at the eascon of the ieee, washington dc. heronemus w.e. (sept. ) the feasibility of windpower utilization in the wisconsin energy market, presented at wisconsin state senate hearings, madison wi. heronemus w.e. ( ) energy alternatives: the need and the possibilities, lecture delivered at many forums, including hampshire college, amherst ma, nov. , . 	 heronemus w.e. ( ) windpower: look backward, then move forward confidently, paper c - , presented at ieee power engineering society meeting, ieee publication -ch - -pwr, new york ny 	 heronemus we. ( ) testimony prepared for the hearings before the energy subcommittee of the senate finance committee on s. energy revenue and development act of , washington dc. 	 heronemus w.e. ( ) alternate energy sources from the ocean, journal of the marine technology society, vol. , no. . 	 heronemus w.e. ( ) pollution-free energy from the oceans, testimony offered to congressman m. mccormick's energy subcommittee of the house of representatives committee on science and astronautics, washington dc. 	 heronemus w.e. ( ) using two renewables, oceanus, vol. xvii, woods hole oceanographic institution, woods hole ma, summer. 	 heronemus w.e. ( ) a survey of the possible use of windpower in thailand and the philippines, prepared for the us department of state, aid/ta/ost, contract no. aid/ta-c- , washington dc. 	 heronemus w.e. ( ) windpower: a significant solar energy resource, aware, june , presented at american chemical society conference, philadelphia pa. 	 heronemus w.e. ( ) an assessment of the wind energy resource available to long island, new york, with fs stoddard, gr whicher, and rf pryblo, report prepared for dubin, mindeli & bloome associates, county of suffolk planning commission, new york ny 	 heronemus we., j. m. mcgowan and g, darkazalli ( ) wind and solar thermal combinations for space heating, proc th intersociety energy conversion engineering conference, newark nj. wind engineering volume , no. , 	 heronemus w.e. ( ), oceanic windpower, presented at "energy from the oceans" conference, north carolina state university, raleigh nc, jan. 	 heronemus we. ( ) wind generated electricity: its application and future, presented at th annual meeting of the american society of heating, refrigeration and air conditioning engineers, los angeles ca, march. 	 heronemus we. ( ) investigation of the feasibility of using windpower for space heating in colder climates, university of massachusetts energy alternative program, prepared for national science foundation grant aer - , report nsfi rann i aer- - ipr/ ii, amherst ma. 	 heronemus w.e.,( ) wind power space heating, with d cromack, proceedings of third biennial wind energy conference, erda, washington dc, sept. . 	 heronemus we.,( ) design and operational aspects of a kw wind turbine generator for residential heating applications, with d.e. cromack and j.g. mcgowan, presented at th intersociety energy conversion engineering conference, washington dc, sept. gipe, paul in ( ) reaping the wind, editor peter asmus, island press. weisbrich a.l. and rainey d. l. warp technology for low cost marine based wind power plants, proceedings bwea conference, cardiff university of wales, meb london. baring-gould, i. ( ) personal communication, national renewable energy laboratory. 	 bearse, bryn ( ) every willing hand 	 heronemus we. ( ) earth connection workshop, university of massachusetts extension. 	 manwell, mcgowan, and rogers ( ) wind energy explained: theory, design, and application, wiley. 	 foudy, jim ( ) pioneer in the valley, daily hampshire gazette, northampton ma, nov. , . 	 golding e.w. ( ) the generation of electricity by the wind, reprinted with additional material by e. & e n. span, london. r esearch a rticle in d o o r/o u td o o r a irflow an d a ir q u ality e-mail: wangxinke@mail.xjtu.edu.cn a method to identify the point source of indoor gaseous contaminant based on limited on-site steady concentration measurements xinke wang (), wei tao, yuanyuan lu, fenghao wang school of human settlements and civil engineering, xi’an jiaotong university, xi’an , china abstract identification of potential contaminant sources in buildings is a n important iss ue for indoor pollutant source control. in this paper, a method based on the characteristics matrix derived from the transport governing equation is proposed, an d the procedur e to identify the contaminant source is presented. compared with the metho ds in the literat ure, the new method is more suitable for the identification of steady point contaminant sources because it only requires limited on-site concentration measurement data without historical information. as a demonstration case, a d room with a known flow field validated by the e xperiment in the literature is selected. a steady point sou rce is presumed at a certain po int and the co ncentration field is calcu lated by computational fluid dynamics (cfd). then the concentration data at the specified sampling points are used to iden tify the source position. with out the measurement error, the method can wor k well when the concentration measurement data at only two sampling points are given. however, when concentration measurement errors are considered, sampling points need to be increased to improve the identification accuracy. for the simulated d case, nine sampling points are sufficient for acceptable accuracy when the relative measurement error is %. effects of po sitions of the source and the sampling points, and the uncertainty of the flow field simulation on the identification results, as well as the limitation of the method are also discussed. keywords source identification, indoor air quality (iaq), steady concentration, computational fluid dynamics (cfd) article history received: november revised: february accepted: february © tsinghua university press and springer-verlag berlin heidelberg introduction people spend more than % of their time indoors (kim et al. ). however, since the energy crisis in s, le ss outdoor fresh air is suppl ied into buildings and more air-tight measure is made in buildings for building energy saving. at the same time, more chemical products emitting lots of chemical contaminants are applied indoors. consequently, indoor air quality (iaq) be comes worse in the urban buildings and some significant adverse symptoms on occupants’ comfort, heal th, productivity arise such a s headaches; eye, nose, or throat irritations; heart disease and even cancer (yang et al. ). source control is a primary and the most effective way to improve indoor air qu ality. however, for source control it is often difficult to identify the locations of t he contaminant sources. an imaginary effective solution to find contaminant source is to measure the concentrations of indoor con- taminants in as many positio ns as possible to identify the point with maximum concentration value as the position of the contaminant source. but in reality, the expense will limit the method. therefore, some modeling methods together with limited sensors are developed. sreedharan ( , ) successfully employed bayesian probability theory to identify the gaseous pollutant source by interpreting real-time monitoring information from the concentration sensor network. recent years, so-called inverse modeling methods were developed rapidly for the more accurate identification of indoor con taminant sources. these inv erse modeling methods were classified as forward meth ods, backward methods and probability methods (liu and zhai ). the forward methods employed a trial-error simulation process to find a contaminant source that can promise the best fitting between the predicted concentration and the measured build simul ( ) : – doi . /s - - - an artificial biomimetic catalysis converting co to green fuels nano news & views open access an artificial biomimetic catalysis converting co to green fuels caihong li and zhiming wang* abstract researchers devote to design catalytic systems with higher activity, selectivity, and stability ideally based on cheap and earth-abundant elements to reduce co to value-added hydrocarbon fuels under mild conditions driven by visible light. this may offer profound inspirations on that. a bi-functional molecular iron catalyst designed could not only catalyze two-electron reduction from co to co but also further convert co to ch with a high selectivity of % stably over several days. keywords: molecular iron catalyst, co , co, ch , visible light background social development and the energy crisis have increased the demand on chemical fuels. furthermore, the increas- ing concentrations of co in the atmosphere owing to human activities such as excessive combustion of fossil fuel, exhaust gas emission and respiration have had a series of terrible impacts including global warming, desertification, and sea level rise. one of the greatest innovations in mitigation of energy crisis and green- house effect was converting greenhouse gases co into fuel chemical feedstock compounds such as ch , co, and other small molecules with visible light (it is called photoreduction, in scientific jargon) [ ]. the most re- markable superiority of photoreduction is that it can be driven by visible light compared to electroreduction which is activated by applied voltage or thermal reduc- tion with high temperature. in addition, approximately half of solar light is located in the visible range. how- ever, the low production rate and selectivity because of multiple reaction pathways and a variety of products se- verely limit large-scale practical application of co reduction. the challenges in catalytic reduction of co to value- added fuels ideally based on cheap and earth-abundant elements rather than on precious metals are efficiency, stability, and selectivity [ ]. so far, the main methods ad- dressing these challenges have fallen into three categories: screening transition metals [ ] with high catalytic activity as active sites such as fe, co, and ni; formation of organic macrocyclic structures to enhance long-term stability [ ]; and ligand modification [ ] to strengthen the desired prod- uct selectivity. in each approach, the selected metal element and the structural design both contribute to the final cata- lytic performance and product selectivity. organic macrocyclic structures (oms) chaining transi- tion metal elements are very popular catalysts used in co reduction, where the metal elements act as catalytic active sites to adsorb and bind the co molecules [ ]. microporous oms can offer larger specific surface area, i.e., more active sites to support catalytic reactions. nevertheless, the original oms may not possess the optimized catalytic performance. structure optimization such as ligand modification would improve the catalytic activity especially product selectivity by inducing internal interactions like h bonds which can stabilize the specific intermediates in favor of gaining desired products. experimental inspired from the photosynthesis of plants, rao et al. [ ] creatively designed a biomimetic photocatalytic system based on a molecular iron catalyst which miraculously produced ch from co at ambient temperature and pressure. such a frontier and significant discovery was published in nature. rao and co-workers judiciously designed an iron (transition metal element) tetraphenylporphyrin (organic macrocyclic structure) complex functionalized with trimethylammonio * correspondence: zhmwang@gmail.com the institute of fundamental and frontier science, university of electronic science and technology of china, chengdu , china © the author(s). open access this article is distributed under the terms of the creative commons attribution . international license (http://creativecommons.org/licenses/by/ . /), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the creative commons license, and indicate if changes were made. li and wang nanoscale research letters ( ) : doi . /s - - - http://crossmark.crossref.org/dialog/?doi= . /s - - - &domain=pdf mailto:zhmwang@gmail.com http://creativecommons.org/licenses/by/ . / groups (ligand modification) as the catalyst to reduce co . this catalytic system was operated in a co -saturated aceto- nitrile (ch cn) solution containing a visible-light photosensi- tizer aiming to capture photons from light irradiation and afford energy (hυ) for the redox reactions as well as a sacrificial electron donor used to provide electrons on photo-induced command by photosensitizer to reduce co . the whole sys- tem was significantly stable and driven by visible light (λ > nm) at atm and room temperature. discussion furthermore, rao et al. first reported that the above catalytic system whose catalyst was known as the most efficient and selective molecular electro-catalyst for re- ducing co to co in two-electron process, could also be applied for the eight-electron reduction [ ] from co to ch . they found an entirely new function of this mo- lecular iron catalyst under moderate conditions. mean- while the authors analyzed and verified the reaction mechanism of two-step procedure that first reduced co to co and then converted co to ch with % of the ch selectivity by isotope labeling experiments and blank experiments for the first time. besides, they also found that a meta-acid condition could play a role of proton donor as well as h bond donor towards stabi- lized intermediates [ , ] but unwished by-product hydrogen selectivity would increase either. greenhouse gas co molecules were adsorbed on the surface of catalyst or more precisely on the metal fe active sites and distorted from the linear structure to a certain angle; thus co molecules were activated [ ] and formed fe–co adduct. in addition, this adduct was further protonated reacting with h+ from solution and formed fe–co adduct dehydrating a h o molecule. the intermediates of co could be obtained through hy- drogenation at this time. then, co molecules were bound to the metal active sites again through subse- quent multistep protonation and electron transfer process and proceeded to yield ch gas eventually deso- rbing from the catalyst surface. later, this catalyst reused to next catalytic cycle of co molecules (fig. ). conclusions the catalytic system they designed was bi-functional, for catalyzing not only relatively simple two-electron reduc- tion to co but also eight-electron reduction to ch util- izing only one catalyst at very easily satisfied conditions. this was a profound progress because a catalyst can catalyze efficiently a certain reaction generally. the uplifting discovery of rao et al. aroused great interest on photoreduction of co to value-added ch and has inspired future efforts in this field. a drawback of this report is that the authors have not deciphered the reduc- tion mechanism in greater detail yet; otherwise, it will help to develop more efficient catalytic system improved from mechanism aspects. cheaper gas fuel may be pro- duced when the productive rate is improved via optimization of structure and conditions. the catalytic system designed by rao et al. has other promising properties besides these described here. for example, it can convert toxic gas co to green fuel ch just by light irradiation. such a simple but significant conversion might guide a new craze to turn waste into wealth environmentally and efficiently. the application and development of their discovery might form the basis of a new branch of co photoreduction or toxic gas conversion. acknowledgements the authors greatly acknowledge the financial support from the national basic research program ( ) of china ( cb ) and national natural science foundation of china . authors’ contributions cl investigated and reviewed relevant papers and then finished this article. zhw has guided and corrected this work. all authors read and approved the final manuscript. competing interests the authors declare that they have no competing interests. publisher’s note springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. received: august accepted: august references . aresta m, dibenedetto a, angelini a ( ) catalysis for the valorization of exhaust carbon: from co to chemicals, materials, and fuels. technological use of co . chem rev : – fig. a sketch map of photoreduction from co to ch li and wang nanoscale research letters ( ) : page of . kornienko n, zhao y, kiley cs, zhu c, kim d, lin s, chang cj, yaghi om, yang p ( ) metal-organic frameworks for electrocatalytic reduction of carbon dioxide. j am chem soc : – . cokoja m, bruckmeier c, rieger b, herrmann wa, kühn fe ( ) transformation of carbon dioxide with homogeneous transition-metal catalysts: a molecular solution to a global challenge? angew chem int edit : – . rao h, bonin j, robert m ( ) non-sensitized selective photochemical reduction of co to co under visible light with an iron molecular catalyst. chem commun : – . morris aj, meyer gj, fujita e ( ) molecular approaches to the photocatalytic reduction of carbon dioxide for solar fuels. accounts of chem res : – . chang x, wang t, gong j ( ) co photo-reduction: insights into co activation and reaction on surfaces of photocatalysts. energy environ sci : – . rao h, schmidt lc, bonin j, robert m ( ) visible-light-driven methane formation from co with a molecular iron catalyst. nature : – . xie s, wang y, zhang q, deng w, wang y ( ) mgo- and pt-promoted tio as an efficient photocatalyst for the preferential reduction of carbon dioxide in the presence of water. acs catal : – . costentin c, passard g, robert m, saveant j-m ( ) pendant acid-base groups in molecular catalysts: h-bond promoters or proton relays? mechanisms of the conversion of co to co by electrogenerated iron( )porphyrins bearing prepositioned phenol functionalities. j am chem soc : - . . neatu s, antonio macia-agullo j, concepcion p, garcia h ( ) gold- copper nanoalloys supported on tio as photocatalysts for co reduction by water. j am chem soc : - . li and wang nanoscale research letters ( ) : page of 	abstract 	background 	experimental 	discussion 	conclusions 	authors’ contributions 	competing interests 	publisher’s note 	references photocatalytic hydrogen evolution catalysts editorial photocatalytic hydrogen evolution vignesh kumaravel ,* and misook kang ,* department of environmental science, institute of technology sligo, ash lane, co., sligo f yw , ireland department of chemistry, college of natural sciences, yeungnam university, gyeongsan, gyeongbuk , korea * correspondence: kumaravel.vignesh@itsligo.ie (v.k.); mskang@ynu.ac.kr (m.k.) received: april ; accepted: april ; published: may ���������� ������� solar energy conversion is one of the sustainable technologies that tackles the global warming and energy crisis. photocatalytic hydrogen (h ) production is a clean technology to produce eco-friendly fuel with the help of semiconductor nanoparticles and abundant sunlight irradiation. titanium oxide (tio ), graphitic-carbon nitride (g-c n ) and cadmium sulfide (cds) are the most widely explored photocatalysts in recent decades for water splitting. as the guest editors, we have comprehensively investigated the role of sacrificial agents on the h production efficiency of tio , g-c n and cds photocatalysts [ ]. the activity of the catalysts was evaluated without any noble metal co-catalysts. the effects of the most widely reported sacrificial agents were evaluated in this work. the activity of the catalysts was influenced by the number of hydroxyl groups, alpha hydrogen and carbon chain length of the sacrificial agent. we found that glucose and glycerol are the most suitable sacrificial agents to produce h with minimum toxicity to the solution. the findings of this study would be highly favorable for the selection of a suitable sacrificial agent for photocatalytic h production. hong et al. demonstrated the photoelectrochemical (pec) efficiency of mose /si nanostructures for h production and carbon dioxide (co ) reduction [ ]. pec deposition coupled with the rapid thermal annealing method was applied to fabricate the electrodes on the si substrate. pec h evolution and co conversion efficiencies of the mose /si electrode were higher in visible light irradiation as compared to dark conditions. kim et al. synthesised monodispersed spherical tio particles with a disordered rutile surface for photocatalytic h production [ ]. the photocatalyst was synthesised through sol-gel and a chemical reduction technique using li/ethylenediamine (li/eda) solution. the samples were calcined at various temperatures to tune the anatase to the rutile phase ratio. the disordered rutile surface and mixed crystalline phase of tio significantly increased the h production under solar light irradiation. idrees et al. reported the photocatalytic activity of nb o /g-c n heterostructures for molecular h production under simulated solar light irradiation [ ]. a hydrothermal technique was utilised to develop the three dimensional nb o /g-c n heterostructure with a high surface area. h production efficiency of nb o /g-c n ( wt. %) was higher than that of pure nb o and g-c n . the photogenerated electron hole pairs were successfully separated through a direct z-scheme mechanism at the heterojunction. kim and woodward described the band gap modulation of tantalum (v) perovskite by anion control [ ]. perovskites such as batao n, srtao n, catao n, ktao , natao and tao f were studied in this work. pt-loaded catao n was utilised as a visible-light-driven photocatalyst for h production using ch oh as the sacrificial agent. son et al. reported the impact of sulfur defects on the h production efficiency of a cus@cugas heterojunction under visible light irradiation [ ]. the activity of the cus@cugas heterojunction was higher as compared to pure cus. this was ascribed to the introduction of structural defects to promote the photo-generated electron hole separation. catalysts , , ; doi: . /catal www.mdpi.com/journal/catalysts http://www.mdpi.com/journal/catalysts http://www.mdpi.com https://orcid.org/ - - - x https://orcid.org/ - - - http://www.mdpi.com/ - / / / ?type=check_update&version= http://dx.doi.org/ . /catal http://www.mdpi.com/journal/catalysts catalysts , , of the recent accomplishments in the synthesis and application of various photocatalysts for h production are briefly reviewed by zhang et al. [ ] tremendous efforts should be taken in the future to commercialise this photocatalytic technology at the industry level. the studies should also be performed with cheap materials, industrial wastewater and seawater for h production. finally, we would like to convey our sincere thanks to all the authors for their significant contributions in this special issue. author contributions: conceptualization, v.k. and m.k.; review and editing, v.k and m.k. all authors have read and agreed to the published version of the manuscript. conflicts of interest: the authors declare no conflict of interest references . kumaravel, v.; imam, m.d.; badreldin, a.; chava, r.k.; do, j.y.; kang, m.; abdel-wahab, a. photocatalytic hydrogen production: role of sacrificial reagents on the activity of oxide, carbon, and sulfide catalysts. catalysts , , . [crossref] . hong, s.; rhee, c.k.; sohn, y. photoelectrochemical hydrogen evolution and co reduction over mos /si and mose /si nanostructures by combined photoelectrochemical deposition and rapid-thermal annealing process. catalysts , , . [crossref] . kim, n.y.; lee, h.k.; moon, j.t.; joo, j.b. synthesis of spherical tio particles with disordered rutile surface for photocatalytic hydrogen production. catalysts , , . [crossref] . idrees, f.; dillert, r.; bahnemann, d.; butt, f.k.; tahir, m. in-situ synthesis of nb o /g-c n heterostructures as highly efficient photocatalysts for molecular h evolution under solar illumination. catalysts , , . [crossref] . kim, y.-i.; woodward, p.m. band gap modulation of tantalum (v) perovskite semiconductors by anion control. catalysts , , . [crossref] . son, n.; heo, j.n.; youn, y.-s.; kim, y.; do, j.y.; kang, m. enhancement of hydrogen productions by accelerating electron-transfers of sulfur defects in the cus@ cugas heterojunction photocatalysts. catalysts , , . [crossref] . zhang, y.; heo, y.-j.; lee, j.-w.; lee, j.-h.; bajgai, j.; lee, k.-j.; park, s.-j. photocatalytic hydrogen evolution via water splitting: a short review. catalysts , , . [crossref] © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . /catal http://dx.doi.org/ . /catal http://dx.doi.org/ . /catal http://dx.doi.org/ . /catal http://dx.doi.org/ . /catal http://dx.doi.org/ . /catal http://dx.doi.org/ . /catal http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	references energy for sustainable development in malaysia: energy policy and alternative energy energy policy ( ) – energy for sustainable development in malaysia: energy policy and alternative energy abdul rahman mohamed, keat teong lee � school of chemical engineering, engineering campus, universiti sains malaysia, seri ampangan, nibong tebal, seberang perai selatan, pulau pinang, malaysia available online may abstract energy is often known as the catalyst for development. globally, the per capita consumption of energy is often used as a barometer to measure the level of economic development in a particular country. realizing the importance of energy as a vital component in economic and social development, the government of malaysia has been continuously reviewing its energy policy to ensure long-term reliability and security of energy supply. concentrated efforts are being undertaken to ensure the sustainability of energy resources, both depletable and renewable. the aim of this paper is to describe the various energy policies adopted in malaysia to ensure long-term reliability and security of energy supply. the role of both, non-renewable and renewable sources of energy in the current five-fuel diversification strategy energy mix will also be discussed. apart from that, this paper will also describe the various alternative energy and the implementation of energy efficiency program in malaysia. r elsevier ltd. all rights reserved. keywords: alternative energy; energy policy; sustainable development . introduction life is a continuous process of energy conversion and transformation. the accomplishment of civilization has largely been accomplished due to the increasing efficient and extensive harnessing of various forms of energy to extend human capabilities and ingenuity. energy is thus one of the indispensable factors for continuous devel- opment and economic growth (rogner and popescu, ). however, at the same time, energy production can contribute to local environment degradation, such as air pollution and global environmental problems, principally climate change. lately, the demand for energy is expected to increase worldwide over the next years (international energy outlook, ), both in the industrial countries and particularly in the develop- ing countries like malaysia where rapid economic growth is expected. fig. shows the energy demand for malaysia in the year , and estimated values for , (thaddeus, ; uk trade & invest- ment, ). it can be seen that the energy demand in malaysia increases rapidly as the energy demand increase almost % within the last years (from to ). the energy demand is further expected to increase to , mw by the year . in order to meet the increasing demand of energy in malaysia, a major challenge facing the power industry will be having an effective and sustainable energy policy. an effective and sustainable energy policy has two main considera- tions. the first consideration is to increase access to affordable, modern energy services in countries that is lacking and secondly, to find the mix of energy resources and technologies (efficiencies) that will reduce the adverse environmental impacts of providing necessary energy services (spalding-fecher et al., ). since all the urban areas and % of the rural areas in malaysia have access to electricity (world employment report, ), the crucial challenge facing the power sector in malaysia currently is the issue of sustainability that is to article in press www.elsevier.com/locate/enpol - /$ - see front matter r elsevier ltd. all rights reserved. doi: . /j.enpol. . . � corresponding author. tel.: + ; fax: + . e-mail address: chktlee@eng.usm.my (k.t. lee). www.elsevier.com/locate/enpol dx.doi.org/ . /j.enpol. . . mailto:chktlee@eng.usm.my ensure the security and reliability of energy supply and the diversification of the various energy resources. the question of security and reliability of supply is critical, to ensure smooth implementation of development projects to spur economic growth in malaysia while diversification of energy resources is critical to ensure that the country is not dependent only on a single source of energy (leo-moggie, ). at the same time, these challenges must be met without having adverse effect on the environment to ensure sustainability. therefore, the aim of this paper is to describe the various energy policies adopted in malaysia to ensure long-term reliability, sustainability and security of energy supply. the role of both, non-renewable and renewable sources of energy in the current five-fuel diversification strategy energy mix will also be discussed. apart from that, this paper will also describe the various alternative energy and the implementation of energy efficiency program in malaysia. . energy policies in malaysia throughout the years, the government of malaysia has formulated numerous energy-related policies in order to ensure the long-term reliability and security of energy supply for sustainable social-economic devel- opment in the country. the various energy policies included the national energy policy ( ), national depletion policy ( ) and fuel diversification policy ( , ). the national energy policy has three primary objectives; supply, utilization and environmen- tal. the first primary objective is to ensure the provision of adequate, secure and cost-effective energy supply by developing indigenous energy resources (both non- renewable and renewable) using least cost options and to diversify supply sources (both from within and outside the country). the second objective is to promote the efficient utilization of energy and discou- rage wasteful and non-productive patterns of energy consumption within the socio-cultural and economic parameters. the final objective is to ensure that factors pertaining to environmental protection are not neglected in the pursuit of the supply and utilization objectives. environmental challenges facing the energy sector cover climatic change, air and water pollution as well as solid waste, which are mainly caused by the increasing use of fossil fuels (hitam, ). on the other hand, the national depletion policy is aimed to conserve the country’s energy resources, particularly oil and gas, as these resources are finite and non-renewable. in this respect, the production of crude oil was limited to an average of , barrels per day (bpd) while the consumption of gas in peninsular malaysia is limited to about , million standard cubic feet per day (mariyappan, ). the fuel diversification policy in malaysia was continuously reviewed to ensure that the country is not too dependent on a single source of energy. table shows the energy mix in malaysia for the year , , and (abdul-rahman, ; biogen, ). since , the malaysian government has implemented the four-fuel diversification strategy in the energy mix. this strategy was implemented after the occurrence of two international oil crisis and quantum leaps in prices in the year and , in which during that time, the malaysian energy sector had been highly dependent on a single source of energy, oil. faced with the possibility of prolonged energy crisis, the government called for the diversification of energy resources away from oil. other options of energy resources available at that time were hydropower, natural gas and coal as there were large untapped indigenous hydropower and natural gas reserves, while coal was considered an abundant worldwide resource with a very low and stable price (thaddeus, ). as a direct consequence of this strategy, the contribution of oil to the energy mix has dropped drastically from a high % dependence in to less than % in as shown in table . on the other hand, natural gas, coal, hydro and biomass contributed . %, . %, . % and . %, respectively to the energy mix. however, using conventional non-renewable energy such as fossil fuels (oil and coal) and natural gas in the energy mix has article in press year e n e rg y d e m a n d ( ' m w ) fig. . energy demand in malaysia. sources: thaddeus ( ) and uk trade & investment ( ). table energy mix in malaysia source (%) (%) (%) (%) oil . . . . natural gas . . . . hydro . . . coal . . . . biomass — — — . sources: abdul-rahman ( ); biogen ( ). a. rahman mohamed, k.t. lee / energy policy ( ) – https://isiarticles.com/article/ development and utilization of integral thin film capacitors procedia environmental sciences ( ) – - © the authors. published by elsevier b.v. open access under cc by-nc-nd license. selection and peer-review under responsibility of beijing institute of technology. doi: . /j.proenv. . . available online at www.sciencedirect.com international symposium on environmental science and technology ( isest) development and utilization of integral thin film capacitors fangfang wang, yajun wang* state key laboratory of explosion science and technology, beijing institute of technology, beijing , china abstract since the deficiency of petrol, electric vehicles have great potential in the future transportation. the paper discusses some batteries used in the electric vehicle. since the unique characteristics, integral thin film capacitors become the research focus. the properties and categories of the materials in the capacitors are introduced, as well as the methods to improve the energy density. © the authors. published by elsevier b.v. selection and/or peer-review under responsibility of beijing institute of technology. keywords: capacitors; electric vehicles; dielectric constant; energy density . introduction energy is the driving force of social development and all the human activities are based on energy, so energy consumption is the premise for social development. life level is directly related to the energy consumption, and the increasing of comfortable life will need consume much energy. energy is always insufficiency for people. how to make a good use of the limited energy has been subject discussed by people and attracted wide attention around the world recently. according to studies, the energy utilization rate is not high, as well as the capacity of energy storage materials is low. so it is necessary for human to find a way to improve energy utilization as far as possible. to develop high performance energy storage capacitor is one significant aspect of new energy resource exploiting. the function of capacitors is storing energy when the energy is sufficient and releasing the stored energy to use when energy is insufficient. at present, the batteries are the main equipment to store electric power, but due to the inherent deficiency of electrochemical cell, such as slow charging and discharging speed, high energy consummation, potential safety problem and so on restrict the application of batteries in high power machinery such as electric vehicles. the capacitors with special physical storage mechanism has great advantage over the batteries for following advantages: not * corresponding author. tel.: + - - . e-mail address: yajunwang@bit.edu.cn. available online at www.sciencedirect.com © the authors. published by elsevier b.v. open access under cc by-nc-nd license. selection and peer-review under responsibility of beijing institute of technology. http://creativecommons.org/licenses/by-nc-nd/ . / http://creativecommons.org/licenses/by-nc-nd/ . / fangfang wang and yajun wang / procedia environmental sciences ( ) – containing harmful metals (such as lead, etc.) will do not cause secondary pollution to the environment, much more charge and discharge cycle times, rapid charge and discharge speed, no change of form of energy during the charge and discharge process, being independent on the ambient temperature [ ]. . energy-storage theory for integral thin film capacitors the energy storage of integral thin film capacitors is influenced by the voltage and capacity, which can be shown in equation ( ) [ ]: e cv ( ) where e refers to the stored electric energy of the capacitors, v refers to the broken-down voltage, c refers to the capacity of the capacitor. from equation ( ), there are two ways to acquire high e, one is to elevate the capacity (c), and the other is to increase the broken-down voltage (v). while in practice, there has been some specific ways to enhance the energy. some are to increase the film number of the integral capacitors, such as mlcc, and others are to use the high dielectric constants materials as the film material, such as bt, ccto or composite. . high permittivity dielectrics dielectrics offering great potential for high energy density and high charge speed can be used in the integral thin film capacitors to replace the discrete surface mount capacitors for bypassing, decoupling, termination and frequency determining functions. so far, there are three kinds of dielectrics used in the capacitors, ceramic dielectrics, polymer dielectrics, and ceramic-polymer composite dielectrics. . . ceramic dielectrics ceramic dielectrics mainly contain two categories, ferroelectric ceramic and semi-conductor. such ceramic has very high dielectric constant ranging from to more than . for example, pb(mg / nb / )o has as high as at room temperature [ ]. though ceramic has considerably colossal permittivity, their flexibility and mechanism are not good. ceramic is hard to be made into films, which restricts its use in thin film capacitors. . . polymer dielectric since s chemists have conducted much research for the dielectric properties of polymers. they found that some polymers have relatively high dielectric constant. the dielectric constant of pvdf is . , higher than that of sio ( . ). they also found that the dielectric constant is related to the polarity of polymer molecule. and most polymers whose dielectric constant is high have large polarity. compared with ceramic dielectric, the dielectric constant of polymer is low, but it has good flexibility and mechanism, which is the advantage over the ceramic in the application of thin film capacitors. . . ceramic/polymer composite since the ceramic and the polymer have intrinsic defaults, and can not meet the demands of the thin film capacitor, scientists try to prepare a composite made of ceramic particles as fillers and polymer as fangfang wang and yajun wang / procedia environmental sciences ( ) – matrix so as to make full use of the advantages of the two dielectrics. the results show that the composite has both high dielectric constant and good mechanism and flexibility. according to the size of the ceramic particles, the composite can be divided into nanocompostie and microcomposite. as the nano-particles have special chemical and physical characteristics, when it is added into the polymer, the composite could has some effects in the interfaces, and such composites have better integrated characteristics, which can be widely used in the thin films capacitors. table shows the dielectric properties of some typical dielectrics. table . the dielectric properties of some typical dielectrics. dielectrics measured conditions dielectric constant ref bt (batio ) , khz ≈ [ ] ccto (cacu ti o ) , khz [ ] pvdf , khz . [ ] bt/pvdf , khz ≈ [ ] . integral thin film capacitors used as the electric vehicles battery since the deficiency of the petrol energy, almost every country and community is dedicated to develop electric vehicles to deal with the energy crisis. electric vehicles use batteries as the power rather than the gas, so it not only can be a good solution to the energy crisis but also release minor pollution such as carbon dioxide to the environment [ ]. as electric vehicle batteries require high energies density, there are several kinds of batteries now which could be used, such as lithium battery, nickel-hydrogen battery, fuel cells. for the considerably high energy density and rapid charge and discharge speed of the integral thin film capacitors, it can be a good choice to the electric vehicles batteries [ ]. lithium ion battery is a conventional battery which has high energy density, being environment friendly and cheap, has attracted great attention of car and batteries manufacturers, but its stability, security and high cost restrict its future application. though nickel-hydrogen battery has rapid charge and discharge speed, its low energy density cannot meet the demands. fuel cells have high energy density, but it is so expensive that manufacturers would not like to use it. while with the unique characteristics, integral thin film capacitors can fully meet the demands of the electric vehicles batteries, and such capacitors have become the focus of research now. table shows the performance of the electric vehicle batteries. table . the performances of electric vehicle batteries [ ]. batteries energy per weight/(wh kg- ) cycling times charging time lithium battery . times . h nickel-hydrogen battery . times . h fuel cells . years don’t need charging thin film capacitors . times - minutes from table , it can be concluded that the thin film capacitors have larger advantage over other batteries in the aspects of energy density, cycling times and charge time. such capacitors can basically improve the role the electric vehicles in the future transportation. nowadays, many countries are dedicated to applying the capacitors to electric vehicles. for example, fangfang wang and yajun wang / procedia environmental sciences ( ) – the fuel cells-super capacitor hybrid vehicle of honda’s fcx is the earliest vehicle which is commercialized. moreover, the capacitors developed by maxwell company have been widely used in variety of electrical vehicles and bicycles [ - ]. . conclusion thin film capacitors have drawn more and more attention for its unique power characteristics and high energy density. it can be the only power source for electrical vehicles as well as hydride power source mixed with other batteries to enhance the power. it is much promising in the field of electrical vehicle by optimizing every technologies. references [ ] yu lf. thin-film capacitor and flat mini thin-film capacitor overview. markets & trends ; : – . [ ] ramaj l. effect of silane as coupling agent on the dieleetrie properties of batio -epoxy composites. composit ; : – . [ ] homes cc, volt t, shapiro sm. optical response of high-dielectric-constant perovskite-related oxide. science ; : – . [ ] subramanian ma, sleight aw. acu ti o and acu ru o perovskites: high dielectric constants and valence degeneracy. solid state sciences ; : – . [ ] dietze m, souni m. structural and functional properties of screen-printed pzt pvdf-trfe composites. sensors and actuators a-physical ; : – . [ ] market t, simpson a. energy storage consideration for grid-charged hybrid electric vehicles. ieee vehicular technologies conference, chicago, ; p. – . [ ] wang hy, zhang jh, yang cr, chen hw. research progress of super ceramic capacitors. electronic components and materials ; : – . [ ] cao bg, cao jb, li jw, xu h, xu p. ultracapacitor with applications to electric vehicle. journal of xi’an jiaotong university ; ( ): – . [ ] xu jh, wang r, chen jk, wang y. research progress on application of supercapacitor in electric vehicles. chinese batteries industry ; ( ): – . [ ] zhang dj, ouyang h, hu h. application of supercapacitor on electric vehicles. auto engineer ; : – . untitled george dura is a research assistant at the centre for european policy studies in brussels. ceps policy briefs present concise, policy-oriented analyses of topical issues in european affairs, with the aim of interjecting the views of ceps researchers and associates into the policy-making process in a timely fashion. unless otherwise indicated, the views expressed are attributable only to the author in a personal capacity and not to any institution with which he is associated. available for free downloading from the ceps website (http://www.ceps.eu) © ceps no. february introduction relations between the european union and belarus have seen little change since president alexander lukashenko came to power in . belarus has languished in a state of self- imposed political isolation despite the subsequent waves of enlargement – most notably, the enlargement which made belarus a direct neighbour of the eu – and the formulation in of the european union’s neighbourhood policy (enp). the eu’s dual-track approach of imposing sanctions and trade restrictions whilst promoting democratisation in belarus have so far yielded minimal results. the eu renewed its offer in december “to the people of belarus” of closer cooperation, in return for a series of democratisation measures, put forward in the form of an unofficial document. today, however, there still exists no framework for political dialogue at the highest level between the eu and belarus. the energy crisis between belarus and russia in december -january created the impression that belarus wished to move closer to the eu. however, one year later, belarus appears to have mended its fences with russia and has toned down its pro-eu rhetoric. the aim of this paper, therefore, is to analyse whether the dynamics of eu-belarus relations have changed at all one year after the oil and gas crisis, and if so, whether the eu has succeeded in increasing its leverage over the country. a first section briefly reviews the eu’s policy towards belarus since the coming to power of lukashenko. next, the paper looks into the oil and gas crisis and examines if russia has radically changed its policy towards belarus, by effectively ending the subsidies. thirdly, we analyse lukashenko’s efforts to offset the effects of the oil and gas crisis and the seriousness of his pro-european rhetoric. the fourth part attempts to verify whether there are any fundamental changes in the dynamics of eu-belarus relations following the oil and gas crisis and speculates on how the eu can engage with the people of belarus more effectively. finally, the paper puts forward a series of short-term and longer- term measures that the eu might consider, on the condition that belarus commits to addressing the most basic requirements in the field of human rights and democratisation. . eu policy towards belarus so far relations between the eu and belarus swiftly cooled down after alexander lukashenko swept to power in . relations further worsened after lukashenko held a referendum in , thereby changing the constitution to extend his presidential mandate until . throughout - , president lukashenko increasingly adopted an authoritarian style of government. as a result, the partnership and cooperation agreement (pca) negotiated in with the eu never entered into force, and neither did the interim trade agreement. at the time, the eu grew concerned with the lack of separation of powers in belarus, the absence of a dialogue between the authorities and the opposition, the worsening human rights conditions and the increasing restrictions on the freedom of the media and press. the eu refused to back belarus’ candidacy for membership to the council of europe and until today, belarus has not yet been accepted as a full member. at the time when the eu was formulating its neighbourhood policy in - , which paved the see european commission, “neighbourhood: a new framework for relations with our eastern and southern neighbours”, march (http://ec.europa.eu/world/ the eu’s limited response to belarus’ pseudo ‘new foreign policy’ george dura | george dura way for closer cooperation with the eu’s eastern and southern neighbours, lukashenko yet again modified the constitution through a grotesquely flawed referendum in , which ensured his possible re-election ad vitam. the lack of democratic reforms and the violation of the most basic human rights in belarus meant that belarus was a priori excluded from the european neighbourhood policy. this has left the eu without a well-defined political and economic framework for conducting its relations with belarus. for well over a decade, the eu has consistently issued declarations and resolutions on belarus, calling for urgent democratic reform, free elections, respect for fundamental human rights and freedom of the media and press. trade, though steadily growing in recent years, has remained below the its potential and eu financial assistance in the period - has totalled a mere € million. the eu has re-directed aid predominantly to projects promoting democratisation, projects with a social vocation or projects linked to the legacy of the chernobyl disaster. the eu also took a number of negative measures and sanctions against belarus, whilst trying to avoid direct harm to the population. these started with the decision to freeze the pca and the interim trade agreement in and to put an end to high-level political contacts with belarus. the european parliament also decided to withhold its assent on any bilateral agreement with belarus. after the flawed presidential election in in belarus, the eu slapped a visa ban on belarus’ leadership. this ban has been renewed on a yearly basis until today and currently comprises persons, including judges and prosecutors involved in the harsh sentencing of opposition activists. the subsequent flawed presidential election in provoked the eu to impose a freeze on the assets of the blacklisted people. in june , the eu also withdrew belarus’ trade preferences under the generalised system of preferences (gsp), after the international labour organisation voiced concern over the curtailing of the rights of trade unions in the country. belarus also faces one of the most restrictive trade regimes with the eu in the textiles sector. other eu partners such as the us and enp/pdf/com _ _en.pdf) and european commission, strategy paper on the european neighbourhood policy, may (http://ec.europa.eu/world/enp/pdf/strategy/ strategy_paper_en.pdf). according to eurostat data, bilateral trade has been picking up since , when the total trade volume stood at € . billion. in , the total trade volume reached € . billion. see the website of the eu tacis branch office in minsk (http://www.delblr.ec.europa.eu/page .html). canada have followed the eu in its visa ban and also frozen the assets of the belarusian leadership. the eu renewed its calls for the democratisation of belarus in december , when the european commission published a non-paper addressed to the people of belarus (in an obvious snub to the leaders of belarus) in which it promises easier travel, increased trade and investment, cooperation in a number of sectoral policies (environment, transport and energy), cultural and educational exchanges, etc., in return for a series of democratisation measures to be carried out by the belarus authorities (see box ). in this document, the eu explains to belarus’ population that their country cannot be included in the enp and benefit from closer ties with the eu if their government does not end its self-isolation by proceeding with democratic reforms. the eu also pledges continued support for the broadcasting of independent tv and radio programmes to belarus and support for belarusian students studying in the eu. the commission’s non-paper has meant significant moral support for the belarusian opposition, adding an element of external legitimacy to their stance against lukashenko’s regime. despite the fact that opposition activists have promoted the document in rallies and marches, so far the non-paper seems to have passed largely unnoticed by the wider belarusian population. in addition, the belarusian leadership did not attach any importance to it, as attested to by the local elections several weeks after the release of the eu’s non-paper, in january , which fell short of democratic standards and where excessive repressive measures were taken against the opposition. for more than a decade, the eu’s dual-track approach of imposing sanctions and trade restrictions whilst focusing its aid efforts predominantly on democratisation has not been able to influence the political situation in belarus: lukashenko remains in power with high rates of popular approval. the eu’s leverage (political and economic) with regard to belarus remains limited, in the absence of overwhelming popular support for the eu membership in belarus (support hovers around %). although the eu’s non-paper puts the ball in the court of the belarusian leadership, belarus has never shown any sign of interest in joining the eu or indeed even its neighbourhood policy. on top of lacking an official framework through which to engage belarus, the eu’s task was further complicated by russia’s overbearing european commission non-paper, “what the european union could bring to belarus”, december (http://ec.europa.eu/external_relations/belarus/intro/ non_paper_ .pdf). the eu’s limited response to belarus’ pseudo ‘new foreign policy’ | presence, whose exclusivist approach with regard to belarus holds no room for a ménage à trois with the eu. however, russia made some changes in its policy at the end of . box . democratisation measures demanded by the eu • respect the right of the people of belarus to elect their leaders democratically – their right to hear all views and see all election candidates; the right of opposition candidates and supporters to campaign without harassment, prosecution or imprisonment; independent observation of the elections, including by belarusian nongovernmental organisations; their freedom to express their will and have their vote fairly counted. • respect the right of the people of belarus to independent information, and to express themselves freely e.g. by allowing journalists to work without harassment or prosecution, not shutting down newspapers or preventing their distribution. • respect the rights of non-governmental organisations as a vital part of a healthy democracy – by no longer hindering their legal existence, harassing and prosecuting members of ngos, and allowing them to receive international assistance. • release all political prisoners – members of democratic opposition parties, members of ngos and ordinary citizens arrested at peaceful demonstrations or meetings. • properly and independently investigate or review the cases of disappeared persons. • ensure the right of the people of belarus to an independent and impartial judicial system – with judges who are not subject to political pressure, and without arbitrary and unfounded criminal prosecution or politically-motivated judgements such as locking-up citizens who peacefully express their views. • end arbitrary arrest and detention, and ill-treatment. • respect the rights and freedoms of those belarusian citizens who belong to national minorities. • respect the rights of the people of belarus as workers – their right to join a trade union and the right of trade unions to work to defend the people’s rights. • respect the rights of the people of belarus as entrepreneurs to operate without excessive intervention by the authorities. • join the other nations of europe in abolishing the death penalty. • make use of the support which the osce, the eu and other organisations offer to belarus to help it respect the rights of its people. source: european commission non-paper, “what the european union could bring to belarus”, december . . shifts in russia’s policy towards belarus for several years, putin had been calling for an end to russian subsidies to the belarusian economy, granted mainly in the form of gas and oil deliveries at preferential price rates. eventually, the belarusian authorities gave in to russian/gazprom pressure and agreed on december to a last- minute protocol (signed on may ) on the supply of oil and gas. the agreement stipulates the acquisition by gazprom of % of beltransgaz – the national belarusian pipeline network which supplies europe and domestic consumers – for $ . billion. it also set down a gradual increase of the gas price paid by belarus to gazprom over the coming years, reaching the ‘european price’ by . as of january , the gas price jumped from $ . to $ per cubic meters, which nonetheless remains very low compared to the average price on the european market of $ . in the first quarter of , the gas price jumped to $ per cubic meters , and is expected to rise to $ in the latter part of . in addition, russian oil companies need to pay a customs fee of $ per tonne for exporting crude oil to belarus, whereas previously this was duty-free. finally, belarus needs to transfer % of the tax revenues from refined oil products to russia. furthermore, russia scrapped plans to build a yamal-europe ii pipeline, connecting russia to europe, through belarus, despite lukashenko’s offer of a five-year transit fee waiver if russia abandoned the idea of the trans-baltic nord stream pipeline. finally, gazprom, which supplies annually billion cubic meters of natural gas to belarus, threatened once again in august to cut gas supplies to belarus by % due to an unpaid belarus news and analysis, “putin orders end to subsidies for belarus”, december (http://www.data.minsk.by/ belarusnews/ / .html). yakov minkov, “can the stronghold withstand an economic attack? the challenges and prospects of the belarusian economy in the near future”, research paper / , office for a democratic belarus and association for international affairs, prague, , p. . belarus news and analysis, “belarus to buy russian gas at $ per cu m in q ”, january (http://www.data.minsk.by/belarusnews/ / .html). interfax, “russian gas could cost from usd to usd per cubic meters for belarus in ’ ”, november (http://www.interfax.com/ / / news.aspx). radio free europe, “russian ambassador dismisses need for second line of pipeline via belarus”, november (http://www.rferl.org/newsline/ / / -cee/ cee- .asp). | george dura gas bill of $ million for gas deliveries in the first half of . the impasse in belarus-russian relations went much deeper than the energy dispute, and must also be sought in the fundamentally opposed visions held by lukashenko and putin about the russia-belarus state union. putin has openly favoured an integration process by the absorption of belarus into a union that russia would dominate, essentially turning belarus into a russian province, whilst lukashenko envisages nothing more than a loose confederation. russia’s earlier gas and oil subsidies allowed the belarusian economy to thrive and to show growth rates averaging % in the three years - , thereby bolstering domestic support for lukashenko. estimates show that preferential prices for gas and the absence of export duties towards russia on refined oil products represented about $ billion in additional revenues for belarus, or about . % of the country’s annual gdp. under the new conditions dictated by moscow, however, lukashenko’s ‘economic miracle’ may become more difficult to sustain. calculations indicate that in , the deficit in the balance of payments caused by the gas and oil shock will be equal to $ . billion. belarus may in the short run continue to rely on adjustment loans granted (increasingly be grudgingly) by the russian federation to cover its budget deficit, but it may become more inclined to consider certain economic reforms, a diversification of its energy supplies and the attraction of foreign capital and trade partners from the eu. on a recent visit to slovakia, valery voronetsky, deputy foreign affairs ministers, was reported to have said that the belarusian government attaches close attention to the development of a favourable investment climate through liberalisation and economic cooperation. if belarus has thus far been able to ignore the eu’s admittedly weak trade pressures, sanctions and declarations about human rights violations and the according to the imf and belarus official statistics, the growth rates were . % in , . % in and % in . yakov minkov, op. cit., pp. - . the figures are for only. belarusian institute for strategic studies, “bleeding belarus: economic outlook after the energy conflict with russia”, january (http://www.belinstitute.eu/ images/stories/documents/bleeding% belarus_economic% outlook.pdf). the national centre of legal information of the republic of belarus, “belarus, slovakia need to intensify cooperation”, valery voronetsky says, december (http://law.by/work/englportal.nsf/newsbelforint/ f dd f c b ?opendocument). need for democratisation, its worsening relations with russia at the end of and for the better part of certainly created the impression that belarus may look now to improve its relations with the eu. the row with russia over gas and oil prices in december -january prompted lukashenko to tone down his anti-european rhetoric. from its side, the eu seemed more inclined than ever to start a dialogue on energy with belarus as brussels became increasingly wary of a possible disruption of russian energy supplies transiting through belarus to europe. . lukashenko’s ‘new foreign policy’ it was not unusual before the gas and oil crisis to hear in minsk that, strategically, the eu cannot offer belarus what its eastern vector can offer in terms of oil and gas prices, markets, loans, etc. since january , the discourse has become a little more nuanced. it is still too early to clearly evaluate the scale of the social and economic impact of russia’s new policy towards belarus, but the country started taking measures early on to offset the effects of the energy crisis as much as possible. belarus introduced the concept of a ‘new foreign policy’ as a way to mark its independence from russia, which was essentially based on two dimensions: diversifying its foreign energy supplies by fostering closer ties with energy-rich countries and adopting a clear pro-eu discourse in official declarations asking for closer cooperation with the eu in several mutually beneficial fields, namely energy. belarus is intent on decreasing its energy dependence on russia. its high-level contacts throughout with venezuela, iran, azerbaijan, nigeria but also norway (all major oil or gas producers) can be seen as an attempted rebuff to russia’s high-handed energy policies and as a wish to reduce belarus’ total dependency on russian energy imports. as part of its energy diversification efforts, belarus is also looking into the possibility of building a nuclear power plant, despite the fact that a large part of its population is still suffering from the consequences of the chernobyl disaster. as regards trade, the belarusian economy has been traditionally geared towards producing manufactured goods for the former soviet market. russia is the second largest trading partner of belarus, after germany, with bilateral trade reaching $ billion. belarusian products are not as competitive on the eu market as they are on russia’s and other cis markets. the customs union between russia and belarus further precludes a free trade agreement with the eu, but the eu- surpasses russia as the leading destination for belarusian exports (in . % for the eu the eu’s limited response to belarus’ pseudo ‘new foreign policy’ | against . % for russia). despite the eu’s trade sanctions and the removal of belarus from the gsp (generalised system of preferences), which represents a loss of roughly € million per year for belarus, trade between belarus and the eu is growing steadily. as part of its declared ‘new foreign policy’, the belarusian leadership has also been making overtures to the eu. in january , lukashenko extravagantly claimed that he would rather adopt the euro and seek eu membership than adopt the russian ruble and join a union with russia under the terms dictated by the kremlin. more seriously, he expressed his wish to see the eu open up its internal market for belarusian products. advocating an open and honest dialogue with the west, he considered that the present moment was favourable for mending ties and has proposed to start cooperating with the eu in mutually beneficial areas, such as energy, transport, illegal migration, etc. belarusian officials have also announced plans to liberalise belarus’ visa regime for eu citizens and express hope that bilateral relations may advance from a simple free trade relationship to more advanced forms of economic cooperation. in addition, belarus is keen to receive investments from the eu. many state-run companies and assets may be privatised in the near future, state assets being estimated at $ billion. attracting foreign, in particular eu investment, thereby, also serves as a safeguard towards future aggressive tactics from russia. lukashenko himself claimed in the aftermath of the energy crisis with russia that “if western energy companies had had stakes in the belarusian energy transport networks, russia would never have acted so brutally” adding that “eyes in european commission, eu-belarus trade in (http://trade.ec.europa.eu/doclib/docs/ /september/ tradoc_ .pdf). charter , “eu decides to impose mini-trade sanctions on belarus”, december (http://www.charter .org/ eng/news/ / / /rada). trade in stood at € . billion, growing by almost % compared to . see (http://trade.ec.europa.eu/ doclib/docs/ /september/tradoc_ .pdf). belarus news and analysis, “lukashenko sets out rare pitch to western investors”, january (http://www.data.minsk.by/belarusnews/ / .html). belarusian ministry of foreign affairs, statement by deputy minister of foreign affairs of the republic of belarus mr. valery voronetsky at the eu conference “working together – strengthening the european neighbourhood policy”, brussels, september (http://www.mfa.gov.by/en/press/official-releases/ fa aad b f cdf.html). charter , “abramovich plans to buy belarusian oil and chemistry industry”, october (http://www.charter . org/index.php?c=ar&i= &c =&i = &p= &lngu=en). russia are sparkling when speaking of future privatisation of belarusian industry”. however, lukashenko’s ‘new foreign policy’ failed to seduce the eu and it did not result in any democratisation at home. instead, the pro-european rhetoric is perceived as being used as an irritant towards moscow. the fears of an economic and social backlash following harsher terms of trade for energy imports from russia have not materialised and lukashenko’s grip on power has not diminished. he is still widely popular and can count on rates of support between and %, while the anti-lukashenko electorate represents slightly over % of the population. the russia-factor remains the key to belarusian foreign policy one way or the other. despite the economic costs resulting from the increased prices for russian energy, relations with russia seem actually to be on the mend, as attested to by a two- day visit by putin to minsk in mid-december . during that visit lukashenko wished to show a relatively united russia-belarus front to the outside world and underlined that “belarus and russia are making an immense contribution to the european continent's economic and socio-political stability” and that “reciprocal steps are expected from the eu” in this regard. however, speculation about speeding up the establishment of a russia-belarus union may not materialise very soon. currently, the bruised bilateral relations need a lot of patching-up. belarus will continue to pay higher prices for gas and oil (this was reconfirmed during the meeting). in return the belarusian government is raising the transit tariff of russian oil headed westward through the druzhba pipeline by % on february , presenting an additional income to the state budget of $ million. this goes against the logic of building a so-called ‘state-union’ in which oil and interview with alexander lukashenko, by alexander rahr in die welt, january (http://www.welt.de/print- welt/article /die_opposition_ist_in_weissrussland_k eineswegs_verboten.html). results are taken from an iiseps opinion poll of may , “trends of change in belarusian public opinion about some social-economic and political problems” (http://www.iiseps.org/etrends.html). official website of the president of belarus, “alexander lukashenko meets with president of the russian federation vladimir putin”, december (http://www.president.gov.by/en/press .html#doc). interfax, “minsk expects reciprocal steps from europe in response to stable energy supply”, december (http://www.interfax.com/ / /news.aspx). belarus news and analysis, “belarus to raise oil transit tariff % on feb ”, january (http://www.data.minsk.by/belarusnews/ / .html). | george dura gas would be as cheap in belarus as in russia. lukashenko’s trust in putin seems to have been shaken by the energy crisis, and he has in any case a record of stalling and restarting the process of building a state-union with russia. since no consensus has been found as to the final shape of the state-union, despite the existence of a draft constitution since . nothing in the latest visit of putin to minsk, where the issue of the state-union was put again on the table after the energy crisis, indicates that lukashenko will act differently this time. lukashenko received a $ . billion loan, which looks almost tailored to cover the $ . billion in losses incurred to the belarusian budget in following the energy crisis. in return, russia received assurances of lukashenko’s willingness to host russian tactical nuclear weapons on his country’s territory in a response to the deployment of a us missile defence shield in eastern europe. despite the impressions created during putin’s visit, there appears to have been no major breakthrough on the state-union. instead, relations with russia almost seem to have gone back to ‘business as usual’. . eu engagement in belarus after the energy crisis over the past four years, eu foreign policy towards its neighbours has evolved substantially, through the formulation of the enp and through the eu’s enlargement to belarus’ neighbours in central and eastern europe. this has created new opportunities for eu-belarus relations. has the russo-belarus energy crisis altered the dynamics of eu-belarus relations? presently, the eu prefers to stick to its previous point that the eu will open up the enp offer to belarus if minsk will start implementing the commission’s non-paper of december , with its list of democratisation measures. however, some member states seem willing to engage even further with belarus. in addition, the european commission has shown signs that it might consider certain forms of dialogue at a more technical level. as things stand at present, belarus is not interested in the enp offer, because the price to be paid by the political elite for strengthening ties with the eu is too high. in terms of aid, the enp might in the best of circumstances offer something between what moldova and ukraine are now set to receive: moldova will receive over € million in the period - , whereas ukraine will receive european commission non-paper, op. cit. bbc romanian news, “voronin-barroso meeting in brussels”, january (http://www.bbc.co.uk/ € million for the same period. in addition to direct financial aid, belarus could also benefit from loans from the european investment bank and european bank for reconstruction and development. the increased bilateral trade through access to the eu’s market would also be beneficial for the belarusian economy. however, the economic benefits of increased cooperation with the eu are dwarfed by the subsidies and economic cooperation with russia, even in the post-‘oil and gas crisis’ setting. in addition, lukashenko would have to democratise belarusian politics and society, thereby seriously jeopardising his future as belarus’ president. he would also have to open up the state- run economy which has been providing so generously for his power base, supporters and closest allies for over a decade. instead, belarus has expressed an interest in developing pragmatic relations with the eu centred on cooperation in certain mutually beneficial areas and based on non-interference in its domestic affairs. in september , the deputy minister of foreign affairs of belarus, valery voronetsky, renewed calls for cooperation at the eu’s conference on “working together – strengthening the european neighbourhood policy” by stating that “we [belarus] offer to carry out serious joint european projects to secure the protection of transit, including the physical security of oil and gas pipelines”. indeed, belarus’ role as a crucial transit country for russian oil and gas cannot easily be overlooked in brussels, especially in view of the eu’s growing dependence on russian energy. a total of . billion cubic meters of russian gas will have transited to the eu via belarus in , . billion of which will have passed through the beltransgaz pipeline and the rest (around billion cubic meters) through the russian-owned belarusian romanian/moldova/story/ / / _voronin_bruxelles .shtml). radio free europe, “eu announces € million in aid for ukraine”, march (http://www.rferl.org/ featuresarticle/ / /f a -f f- bd - a - d d .html). belarusian ministry of foreign affairs, statement by deputy minister of foreign affairs of the republic of belarus mr. valery voronetsky at the eu conference “working together – strengthening the european neighbourhood policy”, brussels, september . see eurostat press release, “russia third trade partner of the eu ”, october (http://epp.eurostat.ec.europa. eu/pls/portal/docs/page/pgp_prd_cat_prerel/pge_ cat_prerel_year_ /pge_cat_prerel_year _ _month_ / - -en-bp.pdf). the eu’s limited response to belarus’ pseudo ‘new foreign policy’ | stretch of the yamal-europe pipeline. around % of the eu’s gas imports from russia transit through belarus, having as their main destination poland, germany and lithuania. gazprom’s take-over of % of beltransgaz, under strong russian pressure, is viewed warily in the eu. the move comes in the midst of european union efforts to formulate a coherent external energy policy. on september , the commission also tabled a proposal for a third energy liberalisation package which “proposes a requirement that third country individuals and countries cannot acquire control over a community transmission system […] unless this is permitted by an agreement between the eu and the third country.” not surprisingly, therefore, energy is one of the areas where the eu and belarus face fairly similar concerns and have decided to take certain preliminary steps towards cooperation. a bilateral delegation of experts on energy met last june, but a follow-up meeting was delayed indefinitely by the eu after the series of arrests of opposition youth activists in august. nonetheless, in the field of energy, the eu is expecting to launch a serious energy cooperation dialogue with belarus and set up an early warning mechanism. without being able to engage official belarus within the framework of the enp, the eu has to explore other foreign policy tools. the eu is intent on continuing and reinforcing its policy towards the belarusian grass-roots and society at large. despite all the anti-european propaganda in the belarusian state-controlled media, opinion polls show that more than % of belarusians support closer cooperation with the eu and that % would vote in favour of vladimir socor, “gazprom taking over the pipelines in belarus”, eurasia daily monitor, the jamestown foundation, may (http://www.jamestown.org/edm/ article.php?article_id= ). european commission, “the gas coordination group evaluates the recent russian-belarus gas dispute”, january , press release ip/ / . see for instance the conclusions of the european council of - march , and the european council’s action plan ( - ) for an energy policy for europe (http://www.consilium.europa.eu/uedocs/cms_data/docs/pre ssdata/en/ec/ .pdf). european commission, proposal for a regulation of the european parliament and of the council amending regulation (ec) no / , p. , september (http://ec.europa.eu/energy/electricity/package_ /doc/ _ _regulation_amending_en.pdf). andris piebalgs, eu energy commissioner, “eu’s response to the global energy challenges”, speech at the vilnius energy security conference, october . grzegorz gromadzki, vitali silitski and lubos vesely, “effective policy towards belarus – a challenge for the their country’s accession to the eu in a referendum. these levels of domestic support for the eu are clearly more than sufficient therefore to justify greater eu involvement in belarus. in the area of democratisation and support for a free and democratic civil society, the eu encounters legal difficulties to provide financial support to civil society organisations, due to the fact that many ngos are not allowed to legally register or are closed down after they register. the eu’s support for opposition movements also remains declaratory and symbolic. the eu will continue to focus its efforts on providing grants to ngos for mainly apolitical and socially-oriented projects. in addition the eu will continue to provide scholarships for students. the eu, for instance, also offers generous financial assistance to the belarusian european humanistic university in exile just across the border, in lithuania’s capital vilnius. however, the eu’s impact remains limited, as long as the belarusian authorities continue to harass ngos and are responsible for individually approving the eu student scholarships. in the field of support to the independent media, the eu seems to have a freer hand. at present, the european commission is supporting through a € million project the production of independent tv and radio programmes that are aired in belarus, by the international satellite tv station rtvi and by the “european radio for belarus” radio station broadcasting from poland. the commission’s aim is to provide objective information about the eu and its policies and about world affairs and belarusian politics. it also intends to launch a project in the coming months that would see the development of electronic content covering the european union and events in belarus. belarus will also benefit from an overall eu media-support project addressed to all enp partners. however, the impact of the eu’s media campaign remains limited. a recent poll has shown that only a small fraction of the belarusian population has watched the rtvi ( . %) or listened to radio stations broadcasting from eu countries. enlarged eu”, european choice for belarus series, stefan batory foundation, warsaw, april , p. . independent institute of socio-economic and political studies (iiseps) national poll: “trends of change in belarusian public opinion about some social-economic and political problems” (http://www.iiseps.org/etrend.html), numbers are for may . media consulta press release (http://www.media- consulta.com/ .htm). belarus news and analysis, “eu to launch two projects for independent media in belarus”, september (http://www.data.minsk.by/belarusnews/ / .html). independent institute of socio-economic and political studies (iiseps) national poll: “trends of change in | george dura furthermore, almost two-thirds ( . %) of belarusians do not have access to the internet. finally, the eu has been unable to provide substantial support to the independent press in belarus. there exist fewer and fewer independent newspapers, which in any case do not have assured access to the state-run distribution service. in addition, journalists who refuse self-censorship are too often prosecuted for libel against political figures. eu policy towards belarus has become more contested in debate between the member states since the enlargement, with neighbouring new member states advocating the opening of a political dialogue and the strengthening of trade relations. despite the publication of its non-paper reflecting a principled, non-compromising approach, the commission has also invited second-tier belarusian officials (i.e. the deputy minister of foreign affairs) to brussels and has also organised talks on energy cooperation, after the energy crisis. in addition, now that belarusian neighbours such as poland, lithuania and latvia have joined the eu and articulate their interests with regard to belarus at eu level, there appears to be a certain lack of coordination. for instance, the eu initially failed to find an agreement in december on the removal of belarus from the gsp due to polish and lithuanian opposition for fears that this would hurt their respective economies. a consensus was finally reached six months later, in june . there is also the question how the eu’s policy towards belarus is perceived by eastern enp states. enp states tend to perceive their relations with the eu as purely bilateral and do not place it in the wider regional context covered by the enp. as a result, enp states do not always support the eu’s policies towards belarus. for understandable cultural and historical ties and above all trade relations, ukraine, moldova and georgia do not always align with eu cfsp statements on belarus, they have not aligned on the visa ban imposed by the eu, and certainly do not intend to introduce trade sanctions. if eu-ukraine relations turn into an enp ‘success story’, this might have some influence on lukashenko. most visibly during the summer of , ukraine and the eu reached an agreement on easing schengen visa restrictions for ukrainians, which entered into force in january . at the belarusian public opinion about some social-economic and political problems” (http://www.iiseps.org/etrend.html). independent institute of socio-economic and political studies (iiseps) national poll: “trends of change in belarusian public opinion about some social-economic and political problems” (http://www.iiseps.org/etrend.html). same time, however, belarusians are faced with the rising cost of schengen visas (up to € ). this is all the more problematic for the people of belarus, given their border with three new eu member states, poland, lithuania and latvia, all of which became part of the schengen area on december . similarly, the eu and ukraine are preparing to negotiate a deep free trade agreement, which would substantially open up bilateral market access, whereas belarus is facing trade sanctions. . conclusion and recommendations the eu retains little effective leverage on the belarusian regime. its engagement in the field of democratisation has to date remained rather modest, since there is little that the eu can do without the cooperation of the belarusian authorities. however, the belarusian authorities are willing to start cooperating on several sectoral issues with the eu. in addition, minsk does not seem to oppose establishing some kind of a political dialogue with the eu, as it may also produce the side-effect of temporarily silencing the opposition. the eu has also made efforts in to define a strategy on central asia, with countries sharing political similarities with belarus. the eu could, therefore, consider a number of additional measures with regard to belarus, such as: • propose the opening of a dialogue on human rights (notably on the imposition of a moratorium on the death penalty, which is used less frequently in recent years, the release of political prisoners, and a halt to the continuous harassment of ngos and political activists). • propose the opening of a dialogue on the disbursement of eu aid to belarusian civil society organisations and students (in order to remove obstacles that prevent eu assistance from effectively reaching ngos and students). • offere direct assistance – as opposed to only financing broadcasts from abroad – to the free press and media within belarus for coverage of eu affairs, through language courses, training roman olearchyk, “eu offers ukraine closer ties to brussels”, financial times, october (http://www.ft.com/cms/s/ / ec b - c - dc-b ad- fd ac.html). eu council, “the eu and central asia: strategy for a new partnership”, may (http://register.consilium.europa.eu/pdf/en/ /st /st .e n .pdf). eu external relations council conclusions on uzbekistan, october (http://register.consilium.europa.eu/pdf/en/ /st /st - re .en .pdf). the eu’s limited response to belarus’ pseudo ‘new foreign policy’ | programmes and visits in brussels. such direct support could consist of financing a number of belarusian ‘eu correspondents’ in brussels, who can report back on the eu in their local newspapers. • reduce the eu visa fee from € to € for various categories of people (without going so far as to offer visa-facilitated travel), such as students, academics, businessmen, human rights activists, civil society representatives, journalists, etc. • continue the technical consultations on energy cooperation and stating the eu’s readiness to invest in belarusian energy infrastructure. other measures that could be considered in a longer- term perspective, provided that the above measures are being implemented with some degree of success, are: • unilaterally draw up an eu-belarus action plan, which would complement the european commission non-paper of december and make the enp offer more concrete. • include belarus in relevant regional cooperation initiatives such as the northern dimension (where belarus is encouraged to participate in expert level cooperation). also perhaps the black sea synergy, which will encompass the eastern dimension of the enp, and will complement sectoral eu programmes in areas like migration, border management, fighting organised crime, security, energy, transport and environment, so as to prepare for an eventual inclusion of belarus into the enp. pledge support for the inclusion of belarus as a member with full rights in the council of europe, provided the human rights issues are addressed. finnish presidency of the eu, “northern dimension policy framework document”, adopted at the helsinki summit on november , p. (http://ec.europa.eu/ external_relations/north_dim/doc/frame_pol_ .pdf). pledge support for the integration of belarus into the wto. additionally, the belarusian authorities could start taking a small number of symbolic steps with a low political price from the list of eu democratisation measures, such as: • release all political prisoners. this would be a highly symbolic gesture for the eu and the belarusian opposition, which would not seem so politically risky for lukashenko, whose popularity remains high. • apply a moratorium on the death penalty. • refrain from obstructing the registration process and the effective campaigning by opposition candidates in the upcoming parliamentary elections in . • allow the registration of belarusian ngos, which would provide the authorities with more transparency regarding the activities of civil society organisations and would allow ngos to freely and openly carry out their activities. • improve the conditions of the labour unions so as to work towards removing the eu’s trade sanctions (the belarusian government has been considering steps in this direction). the january energy crisis between russia and belarus may have made the lukashenko regime more wary of russia and perhaps more inclined to reason with the eu. energy security preoccupies both belarus and the eu. if technical cooperation in this field were successful, it could become a stepping stone towards cooperation in other sectors. the basic limitation for eu-belarus relations is that, strategically, belarus has not so far set itself the ambition of joining the eu, unlike ukraine, moldova and georgia. the belarusian authorities have released a small number of political prisoners in early , under pressure from the west. certain high-level political prisoners (such as alexander kozulin, former presidential candidate, andrei klimau, former deputy and alexander zdzvishku, a journalist) remain in jail. in fact, the european commission has just announced ( january ) that further technical meetings will take place on energy, transport and the environment following the release by belarus of three political prisoners. | george dura references european commission ( ), communication: “neighbourhood: a new framework for relations with our eastern and southern neighbours” (http://ec.europa.eu/world/enp/pdf/com _ _en.pdf). european commission ( ), strategy paper on the european neighbourhood policy (http://ec.europa.eu/world/enp/pdf/strategy/strategy_paper_en.pdf). european commission ( ), non-paper: “what the european union could bring to belarus” (http://ec.europa.eu/external_relations/belarus/intro/non_paper_ .pdf). european commission ( ), proposal for a regulation of the european parliament and of the council amending regulation (ec) no / , p. , september (http://ec.europa.eu/energy/electricity/package_ /doc/ _ _regulation_amending_en.pdf). eu council ( ), “the eu and central asia: strategy for a new partnership” (http://register.consilium.europa.eu/pdf/en/ /st /st .en .pdf). chavusaum, y. ( ), “one year after the european message: reaction of the official minsk to the eu twelve demands”, biss blitz n. / , belarusian institute for strategic studies, brussels. gromadzki, g., v. silitski and l. vesely ( ), “effective policy towards belarus – a challenge for the enlarged eu”, european choice for belarus series, stefan batory foundation, warsaw. guillet, j. ( ), “gazprom as predictable partner. another reading of the russian-ukrainian and russian- belarusian energy crises”, russia/nis visions n. , institut français des relations internationales, paris. haukkala, h. and a. moshes ( ), “staying the course – the options of the west in the face of belarus”, briefing paper , finnish institute for international affairs, helsinki. jarabik, b. and a. rabagliati ( ), “buffer rus: new challenges for eu policy towards belarus”, working paper , fundación para las relaciones internacionales y el diálogo exterior (fride), madrid. lynch, d. ( ), “time for new thinking on belarus”, analysis, eu institute for security studies, paris (http://www.iss.europa.eu/new/analysis/analy .pdf). minkov, y. ( ), “can the stronghold withstand an economic attack? the challenges and prospects of the belarusian economy in the near future”, research paper / , office for a democratic belarus and association for international affairs, prague. socor, v. ( ), “gazprom taking over the pipelines in belarus”, eurasia daily monitor, the jamestown foundation, may (http://www.jamestown.org/edm/article.php?article_id= ). vesely, l. ( ), “between east and west – foreign policy prospects of belarus”, research paper / , association for international affairs, prague. s jra .. edith wharton’s resource aesthetics and the dawn of the american energy crisis alan ackerman situating edith wharton in the context of america’s accelerating petro-culture, this essay argues that her novels critique a society that takes for granted high-volume, nonrenewable energy, and specifically revolutionary new kinds of energy: petroleum, natural gas, and the fossil-fueled power stations necessary for the large-scale, continuous production of electricity. attention to the idiom of energy in the house of mirth and its mirror text, the custom of the country, along with ida tarbell’s history of standard oil and theodore roosevelt’s conservationism, sheds new light on assumptions about moral agency, personal freedom, changing modes of thought, and the environment between  and world war i. the essay shows how wharton’s allegorical treatment of lily bart and undine spragg anticipates the notion of exter- nalities or consequences of industrial activities that affect outside parties but are not reflected in the cost of production. we have become great because of the lavish use of our resources. but the time has come to inquire seriously what will happen when our forests are gone, when the coal, the iron, the oil, and the gas are exhausted, when the soils have still further impo- verished and washed into the streams, polluting the rivers, denuding the fields and obstructing navigation. theodore roosevelt, speech at conference on the conservation of natural resources,  may  the aesthetic is at once … the very secret prototype of human subjectivity in early capitalist society, and a vision of human energies as radical ends in themselves. terry eagleton, the ideology of the aesthetic lily bart, the doomed protagonist of edith wharton’s  novel the house of mirth, discovers too late that she has wrongly “been accustomed to take herself … as a person of energy and resource.” i read this line, which seems a commonplace for personal wherewithal, as an allegory for america’s bur- geoning energy use at the dawn of the twentieth century. in doing so, i aim to advance the work of others in the field of energy humanities who have english department, university of toronto. email: alan.ackerman@utoronto.ca.  edith wharton, the house of mirth (new york: penguin, ; first published ), . journal of american studies,  (), , – © cambridge university press and british association for american studies  doi:./s first published online  june  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core mailto:alan.ackerman@utoronto.ca https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core urged us to consider how specific ways of using energy shape culture and vice versa. patricia yeager, for example, asked in a  editor’s column for pmla what happens if we “make energy sources a matter of urgency to literary criti- cism?” we have only to look at recent postapocalyptic fiction and film to see what has been largely taken for granted, that human societies are organized around specific energy resources and technologies, that we are not only part of a dynamic ecosystem but also capable of depleting it and, in the process, harming ourselves. yeager wonders whether thinking about energy’s “visibility or invisibility” might change the way we read, what we read for, and whether there might be an “energy unconscious” like frederic jameson’s “political unconscious.” in her short column, these questions remain rhetorical, a prompt to the kind of analysis i aim to provide in the pages below. attention to the idiom of energy – including energy anxiety – in the house of mirth and the custom of the country () will shed new light on assump- tions about moral agency, personal freedom, changing modes of thought, and the environmental imagination between  and world war i. thinking about energy involves anxiety because people think about it almost exclusively in the context of limitation. the exponential growth of an industrial economy after , with developments in electricity, the networking of homes, central heating, and more reliable internal combustion engines (among other things), required substantial new inputs and forms of energy on a constant basis. in consequence, as wharton’s exceptionally anxious friend henry adams wrote in the education of henry adams, theirs was a moment of radical tran- sition in which “mechanical energy had … converted itself into thought.” edith wharton charts the tragedy of lily bart in terms of resource depletion within a wasteful, energy-intensive economy that was transforming the land- scape as well as the human experience of time and space. many read lily alle- gorically, as a poetic construct signifying broader sociopolitical themes. in the eyes of her love interest lawrence selden, lily is “the victim of the civilization which had produced her,” and, he imagines, she “must have cost a great deal to make.” that civilization may be defined narrowly as the turn-of-the-century new york leisure class, more broadly as american, or as a new world of indus- try, commerce, and materialism. criticism follows wharton’s own oft-quoted explanation of lily’s symbolic importance in her memoir, a backward glance: “a frivolous society can acquire dramatic significance only through what its  patricia yaeger, editor’s column, “literature in the ages of wood, tallow, coal, whale oil, gasoline, atomic power, and other energy sources,” pmla, ,  (march ), –.  henry adams, the education of henry adams (boston: houghton mifflin company, ; first published ), .  wharton, house of mirth, , .  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core frivolity destroys.” yet, to most, the stakes seem more than frivolous. “change the word ‘frivolous’ to ‘materialistic,’” wrote one critic in , and the story of lily bart assumes a larger significance. edith wharton was one of the first american novelists to adopt the possibilities of a theme which since the turn of the century has permeated our fiction: the waste of human and spiritual resources which in america went hand in hand with the exploitation of the land and the forests. it is not necessary to change wharton’s words to understand what this society destroys as the human, spiritual, or “natural” resources consumed by a heedless petro-culture. the scrapping of the protagonist is foreshadowed from the opening pages, as the “american craving for novelty” frames the observation that there is “nothing new about lily bart.” america’s is not a culture of conservation. “the energy question is, at its core, a human question,” writes imre szeman, “that concerns accounting for the quality of human experience under the fossil fuel economy, reckoning with the increasing precarity of life under fossil fuels … the energy question centres on the values that frame our lives.” active selves shape their world through concrete representations, performances, and objectifications. wharton’s work not only resists the abstraction of early mod- ernism but also highlights the danger of abstraction in human terms, exploring sources of value as such: economic, moral, and aesthetic. she takes an anthropological interest in diverse cultures’ modes of valuing, from modern capitalist to feudal aristocratic societies, a project in fiction that exposes idealist impulses to materialist realities. influenced by extensive reading in ethnog- raphy, sociology, philosophy, and evolutionary science, wharton recognized that value is contingent, not absolute or static, and commented in her journal that it was “salutary now and then to be made to realise ‘die unwerthung aller werthe’ [‘the re-evaluation of all values’].” alone at the end, lily finds that “her standard of values had changed.” but it would be more accurate to say that her earlier idealist “theory of values,” of which she becomes conscious only when altered circumstances cause her to compare herself to a friend, failed to account for concrete particularity, including the material processes of which she herself is a product.  edith wharton, a backward glance (new york: d. appleton-century company, ), .  blake nevius, edith wharton: a study of her fiction (berkeley: university of california press, ), .  wharton, house of mirth, , .  imre szeman, after oil (edmonton: petrocultures research group, ), .  quoted in r. w. b. lewis, edith wharton: a biography (new york: harper & row, ), .  wharton, house of mirth, . edith wharton’s resource aesthetics  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core lily’s “story,” as she calls it (it’s also called a “tragedy” in the novel), cor- responds historically to increased press coverage of the standard oil trust, spurred by ida tarbell’s muckraking series in mcclure’s between  and , as well as the coal strike of , and america’s painful negotiations with its energy industries in these years are a crucial subtext. the society of the house of mirth and of the custom of the country, in which people “were always coming and going” and “buildings are demolished before they’re dry,” takes high-volume, nonrenewable energy for granted and, specifi- cally, revolutionary new kinds of energy: petroleum, natural gas, and the fossil- fueled power stations necessary for the large-scale, continuous production of electricity. “i apprehend,” henry adams wrote to his brother brooks in , for the next hundred years an ultimate, colossal, cosmic collapse; but not on any of our old lines. my belief is that science is to wreck us, and that we are like monkeys mon- keying with a loaded shell; we don’t in the least know or care where our practically infinite energies come from or will bring us to … it is mathematically certain to me that another thirty years of energy-development at the rate of the last century, must reach an impasse. wharton is never so pessimistic and, in fact, often delighted in the techno- logical innovations of her age. nonetheless, reading her novels in this context can help us to reevaluate the energy crisis that defines a historical period, beginning with the second industrial revolution in the s. wharton, like adams, saw her own life within the contours of radical technological and economic change. she was born in , three years after the drake oil well in western pennsylvania launched the american oil industry and twenty before thomas edison established his first coal-fired power station in manhattan. her husband, teddy, bought his first car in . the house of mirth opens with a sighting of lily in grand central station, then undergoing a renovation that would replace steam engine service with a terminal for cleaner and faster electric trains – indicating some awareness of spillover costs associated with fossil fuels – and make it the biggest in the world. the primary motivation of the developers, however, was economic, not environ- mental or health-related, transforming the station, in the words of the chief engineer, “from a nonproductive agency of transportation to a self-contained producer of revenue – a gold mine, so to speak.” the decade-long project to  edith wharton, the custom of the country (), in wharton, novels (new york: the library of america, ), –, , .  henry adams, the letters of henry adams,  vols., ed. j. c. levenson, ernest samuels, charles vandersee, and viola hopkins winner (cambridge, ma: harvard university press, ), volume v, .  chief engineer william j. wilgus quoted in sam roberts, grand central: how a train station transformed america (new york: grand central publishing, ), .  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core enlarge grand central was approved by a board that included cornelius and william vanderbilt, william rockefeller, and j. p. morgan – all prominent members of wharton’s milieu. the reader sights lily there for the first time “in the act of transition.” she stands out from rush-hour traffic as a refreshing vision, yet is less incongruous than she may appear. she is always in transition. lily starts the novel waiting for a train and ends lifeless in a boarding house. a radiant twenty-nine years old in the first chapter, her story dramatizes the destructive capacity of a culture involved in a structural transformation to an unsustainable high-energy system that had been picking up steam from roughly the time of her birth in the s. the adjective “radiant,” a familiar term for transmitting light or heat, appears five times in book one of the novel, always in reference to lily, starting on the first page – “selden had never seen her more radiant.” – and not once in book two. lily’s proves to be a dark or at least deeply paradoxical radiance, anticipating horkheimer and adorno’s remark that “the wholly enlightened earth is radiant [strahlt] with triumphant calamity.” moreover, wharton links lily’s own abstraction of the earth, having “grown up without any one spot of earth being dearer to her than another,” to her ultimate loss of strength – not just “material poverty” but a “deeper empoverishment [sic]” and “inner destitution.” in this respect, lily, like her doppelgänger undine spragg in the custom of the country, who marries, in turn, old-money new york, a french aristocrat, and an american capitalist, represents an emblematic break from old world particu- larism to new world freedom, for better and mostly for worse. undine, whose initials are u. s., takes a similar allegorical journey, though hers is char- acterized by “success” and lily’s by “failure” – terms that wharton is at great pains to interrogate. failure has connotations of ugliness and impoverishment, but success can seem equally “squalid.” whereas lily fails to marry a rich man or to secure her economic future – yet arguably preserves her “real self” – the “conspicuous beauty” of apex city weds a series of men, each wealthier than the last, culminating with the billionaire “railroad king” elmer moffatt (to whom she had been briefly married in poorer days before the novel began). yet she remains perpetually restless and dissatisfied, measur- ing success by “her power of making people do as she pleased.” she is an unvaryingly “radiant creature,” who reads about herself in the new york radiator (the title is wharton’s invention, but it is worth mention that the  max horkheimer and theodor w. adorno. dialectic of enlightenment: philosophical fragments, ed. gunzelin schmid noerr., tr. edmund jephcott (palo alto: stanford university press, ), .  wharton, house of mirth, .  ibid., .  wharton, custom of the country, . edith wharton’s resource aesthetics  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core american radiator company was established in ). her beauty is as vivid as “the brightness suffusing it.” one lover feels the “tempestuous heat of her beauty.” for undine, no lights are too bright, no fire too hot, and “no radiance was too strong.” at the beginning of the house of mirth, selden’s gaze registers lily as a nonhuman resource. at first she refreshes his eyes like a cool stream. then, he imagines her aesthetically as a ceramic doll; “a fine glaze of beauty … had been applied to vulgar clay.” but he checks himself: “a coarse texture will not take a high finish.” in lily, he feels certain, “the material was fine.” selden’s quasi-marxian meditation on the refining of lily’s “material” (“ugly people must … have been sacrificed to produce her”), and how it is “brightened by art,” draws attention to the work of culture and the resources that fuel it, suggesting an analogy, developed later, that associates lily with a cultivated landscape. the reification of lily under the gaze of the male specu- lator (with connotations of romance and finance), the questions of value and costs of production, indicate the much-discussed theme of “conspicuous con- sumption” and wharton’s debt to thorstein veblen’s  theory of the leisure class, which details the “ancillary” role of women as both consumers and consumed in modern society. but questions of cost and value also point beyond the marriage market of high-society new york to a critique of instru- mental reason in a techno-utopian culture and a problem inherent in what recent ecocritics have called “resource aesthetics.” this curious coinage sounds like an oxymoron and points to contradictions in our ways of thinking about both resources and aesthetics. in a  special issue of the journal postmodern culture on resource aesthetics, the editors acknowledge the difficulty of defining their terms inde- pendently, let alone together. the juxtaposition generates immediate tensions: resources are functional, a reserve of materials or money, which can be con- verted into energy to perform work. people use resources to do things. aesthetic experience, on the other hand, is often supposed to be disinterested, impractical, and irrational (there’s no accounting for taste). at least according to kant, aesthetic pleasure does not involve the desire to do anything. so what do these words mean together? the editors’ introduction, “toward a theory of resource aesthetics,” is more suggestive than definitive: resource aesthetics can be said to provoke the contradictions between the instrumen- tal and the beautiful, the literal and figurative, extraction and its representation, in a way that might return the question of visibility to a consideration of the material requirements of aesthetic production, while at the same time insisting on the aesthetics of resource extraction and the recognition of infrastructure as form. or, to put that  ibid., .  wharton, house of mirth, .  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core another way, by thinking the figural iterations of resources and the literal face of aes- thetics, the aesthetics of resources alongside the aesthetic as resource. this passage is gestural, not programmatic. yet, despite its vagueness and con- tradictions, the phrase “resource aesthetics” may help both to shed light on key problems in wharton’s work (e.g. how to read her protagonists’ beauty as a resource to be used or cashed in) and to critique unexamined assumptions that have governed human relations to the material world, particularly in a new world, american context since the second half of the nineteenth century. it also points to an understanding of allegory not as a transparently coded system of signs but as a contentious negotiation between things and ideas. allegory is not a simplistic illustrative technique or “figural iteration” but a mode of critique and site of tension between immanence and transcend- ence. wharton’s economic–environmental allegory supplements her naturalis- tic plots; the psychosocial narrative level of lily’s and undine’s “stories” both signifies other levels of meaning and mixes with them. to treat a human being as a means, rather than an end in herself, is to render “a person of energy and resource” allegorical. aesthetic objects, like lily, who stands out from the “afternoon rush,” appear detached from the dense flux of quotidian material experience. lily is a “figure” of the ideal, of “purity,” abstracted from the welter of the real: “her vivid head, relieved against the dull tints of the crowd.” but, of course, lily is part and product of her material reality, and selden’s way of seeing her designates her as a site of inquiry into contradictions between the instrumental and the beautiful, concreteness and abstraction, resources and capital. i read the custom of the country as a mirror text of the house of mirth. undine spragg’s socioeconomic ascent, powered by her remarkable energy, presents an inverted image of lily’s depletion and decline. reflecting on each other, the two novels suggest an ambivalent commentary on the culture of fossil fuels. undine’s beauty is a mirror image of lily’s; putting it to use, she is determined not to be dominated but to dominate. early in the custom of the country she sees “at a glance that she did not know how to use her beauty” and sets about to rectify her lack of imagination. as she grows older undine gives herself up “to the scientific cultivation of her beauty,” which she uses ultimately to arouse the “aesthetic emotions” of a bil- lionaire industrialist. so does their beauty offer, as terry eagleton suggests, “a vision of human energies as radical ends in themselves which is the implacable  brent ryan bellamy, michael o’driscoll, and mark simpson, “introduction: toward a theory of resource aesthetics,” postmodern culture, ,  (jan. ), at https://muse. jhu.edu/article/, accessed  feb. . edith wharton’s resource aesthetics  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://muse.jhu.edu/article/ https://muse.jhu.edu/article/ https://muse.jhu.edu/article/ https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core enemy of all dominative and instrumentalist thought,” or, as he also suggests, does it inscribe the body “with a subtly oppressive law”? the aesthete selden both speaks of freedom and epitomizes oppression. he takes an impersonal yet “luxurious pleasure” in “the modelling of [lily’s] little ear, the crisp upward wave of her hair – was it ever so slightly brightened by art?” lily is drawn to him by her similar aesthetic education, her “instinctive resistances, of taste, of training” in dry formalism. is selden’s aesthetic detachment morally superior to the sexual desire lily’s beauty excites in others? what is the best way to value beauty, and to what degree can it be termed a possession? these questions point to core themes in wharton’s representation of a wasteful culture. even to speak of aesthetics presumes a culture with a capacity for material waste. “if beauty or comfort is achieved,” veblen wrote, “they must be achieved by means and methods that commend themselves to the great economic law of wasted effort.” beauty, he suggests, is the product of “surplus energy.” acknowledging his pleasure in “the decora- tive side of life,” selden echoes veblen and anticipates eagleton’s assertion that the aesthetic is “a vision of human energies as radical ends in themselves,” lamenting “that so much human nature is used up in the process” of cultivat- ing beauty rather than used as a means toward social or personal betterment. explaining his view that human beings are part of nature’s resources, he expresses conflicted impulses between instrumentalism and formalism: “if we’re all the raw stuff of the cosmic effects, one would rather be the fire that tempers a sword than the fish that dyes a purple cloak. and a society like ours wastes such good material in producing its little patch of purple!” waste is a central trope in many of wharton’s works. in the house of mirth, lily’s fate hinges on what she does with a letter taken from a “brimming” wastepaper basket, the detritus of a rival’s affair. she burns it. more important, she herself becomes a form of waste, “stranded in a great waste of disoccupation.” lily’s beauty inspires diverse responses, from idealiza- tion to lust, that also characterize attitudes toward natural resources. without balancing the conflicting impulses, appreciation and desire, formalism and instrumentalism, the rational pursuit of pleasure and actual sensuous enjoy- ment prove equally destructive forms of objectification. starting with selden catching sight of lily, wharton’s resource aesthetics center on acts of seeing, of being seen, and of occlusion. the optical and deeply gendered vocabulary that has shaped industrial america’s attitudes  terry eagleton, the ideology of the aesthetic (oxford: blackwell, ), .  wharton, house of mirth, .  ibid., .  thorstein veblen, the theory of the leisure class (new york: oxford university press, ), .  ibid., , .  wharton, house of mirth, .  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core toward natural resources was largely formulated by ralph waldo emerson in the decades prior to and including wharton’s birth. as emerson put it in his late lecture “resources” (), “we like to see the inexhaustible riches of nature, and the access of every soul to her magazines.” wharton admired emerson, but, in terms of resource aesthetics, emerson provides an anatomy of masculine love and exploitation, of “husbanding” resources, to which she offers a corrective. for emerson, there is an intrinsic delight in the “plastic power of the human eye.” art, he explains, is the mixture of man’s will with the materials of nature. to regard nature as an artist is para- doxically to compel nature “to emancipate us.” with its aesthetic treatment of natural resources – from fire and wind to steam and coal – nature theorizes a relationship between man and the creative energy of the earth that is purposive and harmonious but also forceful. nature is “fluid, it is volatile, it is obedient.” nature can be put to a variety of human uses; those of a lower order fall under the rubric “commodity,” those of a higher order, “beauty,” but the line between the two is fine and even permeable. “the influence of the forms and actions in nature,” according to emerson, “seems to lie on the confines of commodity and beauty.” the value of natural resources depends on the male gaze and on distinction (“the difference between the observer and the spectacle, – between man and nature”), anticipating a key theme in the house of mirth (e.g. selden calls lily “a wonderful spectacle”), and emerson frames the relationship as a romance in an extended metaphor in the chapter “beauty”: nature stretcheth out her arms to embrace man, only let his thoughts be of equal greatness. willingly does she follow his steps with the rose and the violet, and bend her lines of grandeur and grace … a virtuous man is in unison with her works, and makes the central figure of the visible sphere. in selden, to whom lily has “a kind of wild-wood grace … as though she were a captured dryad subdued to the conventions of the drawing-room,” wharton critiques the exploitative, male-centered ideology implicit in emerson’s commodity–beauty pairing, situating both uses of nature within the context of industrial capitalist accumulation. ideally, for emerson, “all the parts incessantly work into each other’s hands for the profit of man.  ralph waldo emerson, “resources,” in the later lectures of ralph waldo emerson,  vols., ed. ronald a. bosco and joel myerson (athens: university of georgia press, ), volume ii, –, .  the letters of ralph waldo emerson,  vols., ed. ralph l. rusk and eleanor tilton (new york: columbia university press, , –), volume iv, .  ralph waldo emerson, nature (), in emerson, essays and lectures (new york: the library of america, ), –.  ibid., .  ibid., .  ibid., .  wharton, house of mirth, . edith wharton’s resource aesthetics  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core the wind sows the seed; the sun evaporates the sea,” and so on; but the lan- guage of “profit” undoes idealism and harmony. the pleasures of the “trans- parent eyeball” tip easily into the opacity confronting a detached perspective, as the house of mirth vividly illustrates. selden’s thoughts fall far short of “greatness,” and his appreciation of lily is only marginally more “virtuous” than that of her predatory admirers. an attitude of pleasurable speculation has characterized representations of new world resources from columbus’s time to our own. to emerson, the globe is a “great factory,” and, as few will deny, “this world belongs to the energetic.” dominion of nature is inex- tricable from aesthetic appreciation. “toward a resource aesthetic,” its authors suggest, designates “a matter of critical method, of interpretation.” we might describe such a methodology as a form of materialism that takes idealism as its subject. it aims to deconstruct the opposition between inner and outer nature and to critique technological activity that objectifies nature, whether in a formalist or an instrumentalist attitude of domination. most important, it acknowledges an objective reality that is both outside human cognition and historically contingent. as horkheimer and adorno argue in dialectic of enlightenment, instrumental rationality is premised on a domination of nature and turning subjectivity to objective uses, which inev- itably leads to the destruction of humanity and the assimilation of all forms of culture into an industrial model: “anyone who resists can survive only by being incorporated.” this is precisely what lily refuses to do and what undine does in spades when she marries the president of the apex consolidation company. whether undine, who is “fiercely independent and yet passionately imitative,” is beyond good and evil or has most fully internalized conventional morality, with its colonizing approach to material resources, remains open to question. deeply versed in aesthetic theory, wharton herself represents the aesthetic as a contradictory socioeconomic construction, one that is associated both with the highest form of subjectivity, an end in itself, and with a project that can challenge a prevailing capitalist ideology. hermione lee comments, for example, that wharton’s early nonfiction – the decoration of houses () and italian villas and their gardens () – takes up “a complex cul- tural argument about america at the turn of the century. one of the key topics in this argument was the morality of taste, something that interested her very much.” lily and undine literally embody this complexity, as subjects and objects, as both creators of beauty and objets d’art themselves. often described  emerson, nature, .  emerson, “resources,” .  horkheimer and adorno, dialectic of enlightenment, .  wharton, custom of the country, .  hermione lee, edith wharton (london: vintage, ), .  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core by her friends as “the beautiful miss bart,” lily herself is an aesthete (“how she loved beauty!”), with “an artistic sensibility which made her feel herself their superior.” resources are extracted, abstracted, and ultimately, in their highest – or least instrumental – form, aestheticized. the beautiful lily, who seems to epitomize the freedom and autonomy of the bourgeois subject, ends the novel in “the rubbish heap.” far from being a marxist, selden is an enabler of, and parasite on, the capitalist order that produces and consumes her. yet his reflections in the book’s opening pages raise questions about resources that, in stephanie lemenager’s terms, are often “hidden … in plain sight.” a “glaze of beauty” requires a kiln’s high heat, and it takes for granted a set of material forces and social relations. in short, wharton’s figura- tive language of “resources” raises questions about the cost of “aesthetics.” early in the house of mirth, we are told that lily’s “last asset” and only “raw material” is her beauty. her friend gerty farish regards her loveliness as “a natural force,” while recognizing that lily’s heedless use of her “power” must “despoil” others. here too, the moral value of energy has a gendered dimension. invariably positive when associated with men, the rhet- oric of “energy” is equivocal in describing women. numerous female charac- ters in the book are intensely energetic. lily sighs, for instance, “to think what her mother’s fierce energies would have accomplished” in advancing her marriage prospects, “had they been coupled with mrs. peniston’s resources.” yet her horrible, resentment-driven mother is also characterized by her “crude passion for money,” while her aunt simply drains her: “there was a static force in mrs. peniston against which her niece’s efforts spent them- selves in vain.” lily, we are told, “had abundant energy of her own, but it was restricted by the necessity of adapting herself to her aunt’s habits.” edith wharton herself was widely regarded by both contemporaries and later biogra- phers as a person of extraordinary energy, though the former were apt to regard energetic women, less sympathetically, as bossy and headstrong. in a letter to henry james, henry adams referred to her “feminine energy,” and james himself was – or at least played at being – taken aback by her intensity. he called her an “angel of devastation” and, as if wharton herself were a high-powered motor, spoke semi-humorously of the “iridescent track of her devastation.” r. w. b. lewis comments on wharton’s “almost unbelievable  wharton, house of mirth, . others have discussed lily as commodity; cf. lois tyson, “beyond morality: lily bart, lawrence selden and the aesthetic commodity in the house of mirth,” edith wharton review, ,  (fall ), –.  stephanie lemenager, living oil: petroleum culture in the american century (new york: oxford university press, ), .  wharton, house of mirth, .  ibid., .  adams, letters, volume vi, ; henry james, the letters of henry james,  vols., ed. leon edel (cambridge, ma: harvard university press, ), volume iv, . edith wharton’s resource aesthetics  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core energy.” however, a late chapter of the letters of edith wharton, which lewis coedited, is entitled “the costs of energy,” a theme more deeply explored in lee’s biography. the narrative arcs of numerous wharton works chart a course from energy to depletion. at the end of the age of innocence, which is set in the s but concludes close to the date of publi- cation in , newland archer’s wife may waits for him, “radiating the fac- titious energy of one who has passed beyond fatigue.” wharton herself continually oscillated between energy and exhaustion. “for a woman who was so often ill,” writes lee, wharton “showed phenomenal energy.” no one’s energy is limitless, though many in the house of mirth suffer from this illusion. the word “energy” derives from the greek energeia, which means activity or potentiality. for aristotle, energy meant being awake. ancient philosophers adapted aristotle’s word energeia to describe energy in matter, as a kind of élan vital, and to denote vital qualities in individuals and societies. energy as such is invisible; what we see are its effects in matter, from which we deduce a common definition of energy as capacity for work. wharton uses the term this way, and for her there is always an economy of energy. in the custom of the country, the word appears mostly in relation to undine’s old-new york husband, the weak and financially strapped ralph marvell, whose “partners were quick to profit by his sudden spurt of energy,” but who, worn down by “mechanical drudgery” and lacking the resources of (or demanded by) his ex-wife, kills himself. lily’s limited resources are applied to the aesthetic work of cultivating her beauty (her key resource), but her cre- ativity is also constrained by concrete, local factors of which she often seems unaware. lily’s tragedy is to incur a terrible debt for which she pays with her life, overdosing on a drug with which she hopes to still the “supernatural lucidity of her brain,” and going to sleep forever. the greater the expenditure of mechanical energy around her, the less her own internal resources. one of the problems in the house of mirth, as in the broader culture, is that women seem a resource for use. lily’s own, often unconscious, assumptions about life in the fast lane are material and moral. in the second chapter, on the train from new york to a country estate, she encounters the first of her über-rich suitors, percy gryce. the speeding train flings her into his arms, signifying the impact of modern, mechanized transportation on human relationships, including  lewis, edith wharton, xii.  “the costs of energy: –,” in the letters of edith wharton, ed. r. w. b. lewis and nancy lewis (new york: charles scribner’s sons, ), –.  edith wharton, the age of innocence () in wharton, novels (new york: the library of america, ), –, .  lee, .  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core courtship. linking herself to the commodification of american ideals, she aims (unsuccessfully) to become “what his americana had hitherto been: the one possession in which he took sufficient pride to spend money on it.” after struggling to generate conversation with the dull-witted young man – in wharton’s words, “to set his simple machinery in motion” – lily touches on this “last resource,” the topic of his americana and the aestheticizing, or fetishizing, of america. gryce reads reviews of american history solely in the hope of finding his own name, a form of narcissism that indicates a para- doxical liberation from particularity along with an oppressive logic of simplifi- cation and abstraction. the gryce collection, of which he is excessively proud, is the largest, most valuable in the world, and it is the direct product of a mech- anical invention that wharton deftly disparages for its hostility to the natural environment. gryce’s father, jefferson gryce, had made a fortune “out of a patent device for excluding fresh air from hotels.” the first modern electrical air conditioning unit had actually been invented in . as wharton com- ments in a backward glance, that i was born into a world in which telephones, motors, electric light, central heating (except by hot-air furnaces), x-rays, cinemas, radium, aeroplanes and wireless telegraphy were not only unknown but still mostly unforeseen, may seem the most striking difference between then and now; but the really vital change is that, in my youth, the americans of the original states, who in moments of crisis still shaped the national point of view, were the heirs of an old tradition of european culture which the country has now totally rejected. however debatable wharton’s assessment of european tradition vis-à-vis american novelty, the house of mirth shows that these categories of change – the technological and the moral – are inextricable. the age was also that of the most energetic politician in american history. republican president theodore roosevelt, whom wharton remembers as “a friend” in a backward glance, was, in her words, “so alive at all points, and so gifted with the rare faculty of living intensely and entirely in every moment as it passed, that each of those encounters glows in me like a tiny morsel of radium.” henry james described him as “a wonderful little machine: des- tined to be overstrained.” the nature writer john boroughs compared him to an electric battery. one senator called roosevelt a “steam engine in trousers”; to another observer he was “a volcano of electricity.” in ,  wharton, house of mirth, .  wharton, a backward glance, –.  ibid., .  henry james, selected letters, ed. leon edel (cambridge, ma: harvard university press, ),  jan. , .  francis e. leupp, the man roosevelt: a portrait sketch (new york: d. appleton & company, ), . edith wharton’s resource aesthetics  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core less than two weeks after his second inauguration, wharton had dinner at the white house, seated at the president’s right hand. the energetic roosevelt was not only the iconic but also the pivotal figure of america’s ramped up petro-culture. hardly an enemy of big business, despite his trust-busting, roosevelt began his presidency by resolving a labor dispute in the coal industry – then the primary source of energy in america, heating nearly every building in the urban northeast – but he also contested prevailing assumptions about america’s unlimited resources, setting the terms for future debates. in his first address to congress in december , he preached the conservation of resources, which became a major theme of his administration. at a meeting of the society of american foresters in march , he insisted that the primary object of his forest policy was not to preserve forests because they are beautiful though that is good in itself; not to preserve them because they are refuges for the wild creatures of the wilderness though that too is good in itself but the primary object of the forest policy as of the land policy of the united states, is the making of prosperous homes. he returned often in  to “home-making” as the principal justification of his policy for preserving “a steady and continuous supply of timber, grass, and above all water.” he spoke from “the standpoint … of the far-seeing citizen, who wishes to preserve and not to exhaust the resources of the country, who wishes to see those resources come into the hands not of a few men of great wealth, least of all into the hands of a few men who will speculate in them; but be distributed among many men.” distinguishing between the beautiful and the sustainable, roosevelt emphasized economy, touching on one of wharton’s central themes, home-making, and acknowledging diverse interests that the idealistic selden elides. roosevelt attempted to balance energy and economy on the fulcrum of aesthetics in a conservation address at stanford university in : “there is nothing more practical in the end than the pres- ervation of beauty, than the preservation of anything that appeals to the higher emotions in mankind.” deploying aesthetics to promote resource conserva- tion, deconstructing the instrumentalist–formalist opposition, roosevelt’s speech illustrates how aestheticizing resources could shape national policy. the proliferation of new technologies in wharton’s world, as in her novel, functions metonymically, illuminating (figuratively and literally) characters’ successes and failures. when she reaches her friends’ estate at bellomont,  see william r. nester, the war for america’s natural resources, –, and  speeches, at www.theodore-roosevelt.com/images/research/txtspeeches/.txt; www.theodore-roose- velt.com/images/research/txtspeeches/.txt.  theodore roosevelt, “remarks at leland stanford jr. university,”  may , at www. presidency.ucsb.edu/ws/?pid=, accessed  july .  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core http://www.theodore-roosevelt.com/images/research/txtspeeches/ .txt http://www.theodore-roosevelt.com/images/research/txtspeeches/ .txt http://www.theodore-roosevelt.com/images/research/txtspeeches/ .txt http://www.presidency.ucsb.edu/ws/?pid= http://www.presidency.ucsb.edu/ws/?pid= https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core lily finds that electric light makes her appear “hollow and pale,” so she turns out the wall lights and peers at herself between candle flames instead, obliquely implicating the newer, mass-powered technology in her ill appearance. late in the book, nearing her lowest point, lily sinks down on a bench “in the glare of an electric street-lamp. the warmth of the fire had passed out of her veins … but her will-power seemed to have spent itself in a last great effort, and she was lost in the blank reaction which follows on an unwonted expenditure of energy.” the over-brightness of the inefficient incandescent bulbs, first installed along broadway between fourteenth and twenty-sixth streets in , and lit after  by edison’s power station, is inversely related to lily’s depletion. according to edison, a reporter for the new york times remarked in , the lights “will go on forever unless stopped by an earth- quake.” lily has no such luck. one hundred years later, concerns about vast power grids prompted the us energy policy act of . however, by , even edison had begun to recognize the excessive power demands of built environments and to seek ways to supplement fossil fuels with renewables such as wind. edison and ford also developed an electric car, and the story of how gas- oline-powered motors ultimately – but not inevitably – pushed electric vehi- cles out of the market is a crucial subtext of wharton’s work, in which both gasoline and electric-powered cars appear. a  new york times article on the national automobile show at madison square garden claims that women in particular went to examine the four makes of electric vehicles on display. “small electric runabouts” were popular with women, according to the times, because “early gasoline cars required more strength to crank than most women possessed. another great advantage of the electric in years gone by was their quiet operation, in comparison with gasoline cars, and this fact alone was responsible for their widespread use by women.” wharton, who loved “motors,” might have disputed the assumption about women’s strength, but she appreciated the capacity of cars, whether electric- or gasoline-powered, to play a role in women’s liberation – at least for those of means. the freedom, in time and space, that cars enabled, however, also involved acceptance of and submission to a socioeconomic regime that not only takes infinite energy for granted but also ignores hidden costs. the dust alone from cars, not to mention the exhaust, had a major impact on  wharton, house of mirth, .  “electric cars attract attention,” new york times,  jan. , accessed  june , at http:// query.nytimes.com/mem/archive-free/pdf? res=edaeacacdcf; https://energy.gov/articles/history- electric-car. edith wharton’s resource aesthetics  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core http://query.nytimes.com/mem/archive-free/pdf?res= e da e a c a c d cf http://query.nytimes.com/mem/archive-free/pdf?res= e da e a c a c d cf http://query.nytimes.com/mem/archive-free/pdf?res= e da e a c a c d cf http://query.nytimes.com/mem/archive-free/pdf?res= e da e a c a c d cf https://energy.gov/articles/history-electric-car https://energy.gov/articles/history-electric-car https://energy.gov/articles/history-electric-car https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core rural roads in particular; in stephen kern’s words, they “engulfed pedestrians and cyclists and ruined the crop of lettuce farmers.” electric cars quickly became popular with both sexes, not only for running more easily and quietly but also because they did not spew exhaust. in  ferdinand porsche invented the world’s first hybrid electric car. electric cars made up roughly a third of the auto market at the turn of the century, and a fleet of electric taxis served new york city. wharton’s story “the touchstone” refers offhandedly to the ubiquity and reliability of electric taxis. in , a group of wealthy investors, led by august belmont (a model for gus trenor, the owner of bellomont in the house of mirth), execu- tives from standard oil, and edison’s personal secretary samuel insull, founded the woods motor vehicle company to produce electric cars. charging stations also evolved in the first decade of the twentieth century to meet demand, and readers can find a model in mrs. norma hatch’s electric victoria in the house of mirth. by the s, however, electric cars had been driven off the road by ford’s introduction of mass production of the model t in , which made gasoline-powered cars more affordable and quicker to market. another determinant was the exponential increase of texas crude oil production in the decades following discovery of the “spindletop gusher” and development of america’s first major oil field in . the profit-maximizing logic of private enterprise and the lack of public awareness, let alone laws, to restrict pollution or set limits on the exploitation of natural resources simply deferred clear thinking about an energy crisis that some, such as edison and roosevelt, already anticipated. economics rather than environmentalism largely shaped early conversation about conservation of resources. in , industrialist and railroad man james j. hill gave a speech at the white house entitled “the natural wealth of the land and its conservation” at the first conference on the conservation of national resources. following roosevelt’s lead, hill framed it as a problem of economic waste: “for the first time there is a national protest, under seal of highest authority, against economic waste.” without directly critiquing the fossil-fuel economy, wharton’s allegorical treatment of lily bart nonethe- less anticipates the notion of externalities or consequences of industrial activ- ities that affect outside parties but are not reflected in the cost of production.  stephen kern, the culture of time and space: – (cambridge, ma: harvard university press, ), .  heather rogers, “current thinking,” new york times magazine,  june , at www. nytimes.com////magazine/wwln-essay-t.html, accessed  feb. .  “the natural wealth of the land and its conservation,” address delivered by mr. james j. hill, white house, washington, at the conference on the conservation of national resources, – may , at https://archive.org/details/naturalwealthoflhilluoft.  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core http://www.nytimes.com/ / / /magazine/ wwln-essay-t.html http://www.nytimes.com/ / / /magazine/ wwln-essay-t.html https://archive.org/details/naturalwealthofl hilluoft https://archive.org/details/naturalwealthofl hilluoft https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core lily cannot survive a techno-modernity that whizzes like an express train “with a deafening rattle and roar,” and in which, as british welfare economist arthur pigou wrote, “costs are thrown upon people not directly concerned, through, say, uncompensated damage done to surrounding woods by sparks from railway engines.” the irony is that lily has ignored those sacrificed “in some mysterious way” for her benefit, yet she becomes the emblematic victim of an economy from which she unconsciously profits. lily personifies the concept of externalities or nonmonetary “spillover” effects – costs not taken into account or paid for by those who cause the damage. this concept has become central to environmental economics, and lily’s demise instantiates her society’s nonmonetary impacts. for instance, her feeling of moral defilement is figured as nature polluted: “everything in the past seemed simple, natural, full of daylight – and she was alone in a place of dark- ness and pollution.” as gryce’s narcissism is emblematic of the anthropo- centric “machinery” of the broader culture, ford could truly find his name anywhere, thanks to his abstraction of america’s resources, linking the assem- bly line (abstraction of labor) to the fossil-fueled economy’s preeminent symbol of abstraction: the model t. lily bart’s final, failed attempt to make a living for herself happens on an assembly line in a millinery establishment. new forms of energy use, from gas ovens to electric lights, define key moments of lily’s decline. excessive energy consumption metaphorically initi- ates her death scene: “it was as though a great blaze of electric light had been turned on in her head, and her poor little anguished self shrank and cowered in it.” yet the scene in which lily is most explicitly identified with an american landscape (despite her lack of “real intimacy with nature”) occurs with selden on the hilly estate of bellomont in the hudson valley. there she seems part of the “harmony of things.” she projects herself onto the landscape, or abstracts it to fit her mood: “the landscape outspread below her seemed an enlargement of her present mood, and she found something of herself in its calmness, its breadth, its long free reaches.” the romantic pair has a momentary experi- ence of freedom and expanded horizons that leads to a philosophical dialogue. how would selden define “success,” she asks? success means “personal freedom,” he explains, “from everything – from money, from poverty, from ease and anxiety, from all the material accidents. to keep a kind of republic of the spirit.” wharton punctuates this famous “republic-of-the-spirit” con- versation with the appearance of a machine in the garden, a motor, “like the  wharton, house of mirth, ; arthur cecil pigou, the economics of welfare (london: macmillan and company, ), .  wharton, house of mirth, .  ibid., .  ibid., .  ibid., . edith wharton’s resource aesthetics  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core hum of a gigantic insect.” the appearance of the motor does not simply intro- duce the counterforce of history and materialism into a pastoral idyll. in  the car, unlike the train that lily takes to get to bellomont, represents a radi- cally new technology untethered to schedule or track. the motor is a metaphor for “material accident,” which ironizes the ineffectual selden’s theorizing of absolute freedom with, in lily’s view, an unwonted “energy of affirmation.” however, selden is not merely ineffectual and blind to the irony of his ideal- ism; he also represents a profoundly destructive attitude. as jonathan joseph wlasiuk shows in his  dissertation “refining nature: standard oil and the limits of efficiency, –,” american republican ideology was reim- agined in the gilded age to equate political freedom with laissez-faire econom- ics, with significant ramifications for americans’ relationship with the material world. the standard oil company, he convincingly argues, owed its success to this altered republican ideology and the legal regime that enabled the rise of the corporation and despoliation of the environment. the lawyer, selden, epito- mizes this attitude in his republic-of-the-spirit speech, a republic lily insight- fully critiques as a “closed corporation.” as alan trachtenberg points out in the incorporation of america, “the rhetoric of success continued to hail the self-made man as the paragon of free labor, even as the virtues of that fictive character grew less and less relevant. thus, incorporation engendered a cultural paradox.” rockefeller, who incorporated standard oil in , brooked no competition. he recognized the duplicity of the rhetoric selden uses, saying, “the day of combination is here to stay. individualism has gone never to return.” nonetheless, like selden, rockefeller nominally embraced the republican rhetoric of self-discipline and positive thinking. success, a magazine founded by orison swett marsden in , promulgated a will-to-success phil- osophy that represented success in the acquisition of wealth and power as a virtue in itself. when mcclure’s began exposing standard oil’s unfair business practices, success published “an impartial study of john d. rockefeller” ( july ). the principal goal of rockefeller’s ruthless drive toward organization and efficiency was the elimination of what selden calls “material accident.” contemporaneous with the house of mirth, ida tarbell’s best-selling history of standard oil, which had been serialized in mcclure’s magazine from  to , while ignoring the corporation’s massive and devastating impact on the environment, established it as the model of twentieth-century corporate practice, vertical integration, and apparent elimination of produc- tion costs, through actual disguising or downloading of those costs to the  ibid., .  alan trachtenberg, the incorporation of america: culture and society in the gilded age (new york: hill and wang, ), .  ibid., .  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core public. it also inspired roosevelt to bust rockefeller’s trust following passage of the hepburn act (), which asserted the federal government’s right to regulate interstate commerce. defining “success” in a way that reflects ironic- ally on selden’s republican idealism, tarbell cites an  report of the cleveland board of trade: “each year has seen greater consolidation of capital, greater energy and success in prosecuting the business, and, notwith- standing some disastrous fires, a stronger determination to establish an immov- able reputation for the quantity and quality of this most important product.” yet tarbell’s downplaying of environmental costs, such as “disastrous forest fires,” also highlights the problem of ignoring such externalities. many clevelanders complained of extremely damaging impacts to their health and environment of standard oil’s practices (well beyond “some disastrous fires”). one composed a poem entitled “song of the sick water-nymph,” which indicates hidden costs of corporate success: faugh! what a smell! how can i be well? stinking again, small pipe and main, even large reservoir yields to its power! … petroleum, slaughter-house gore, to say nothing of acid sulphuric, and how many more in our waters placid … in the house of mirth, nymphs cavort across a flower-strewn sward in tableaux vivants funded by the stock-market killings of the wellington brys. lily herself appears, in a coup de théâtre, as the neoclassical title figure in joshua reynolds’s  painting mrs. lloyd carving her husband’s name on the trunk of a tree. it is a moment of triumph. in that pose she inflames the hardly disinter- ested male gaze of lovers and lechers alike; she seems “the real lily bart, divested of the trivialities of her little world, and catching for a moment a note of that eternal harmony of which her beauty was a part.” spectators, including selden, are stunned by her performance of decorative, idealized womanhood. no one can tell where nature ends and artifice begins, for the “real lily” seamlessly combines “flesh and blood” with “artistic intelligence.” she appears to be in “harmony” with a pastoral landscape, staged in a marble  ida tarbell, the history of standard oil (new york: mcclure, phillips, and co. ), .  quoted in jonathan joseph wlasiuk, “refining nature: standard oil and the limits of efficiency, –,” dissertation, case western reserve, , .  wharton, house of mirth, . edith wharton’s resource aesthetics  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core mansion on fifth avenue. but lily has commodified herself, trading her sup- posedly natural resources too cheaply on the sexual market of new york’s beau monde (to the extent that gus trenor treats her like a high-priced courtesan). in the end, more like the sick water nymphs of cleveland than the most famous instance of idealized womanhood in new york, the statue of liberty, floral lily will be crushed by a hidden debt she unwittingly incurs. her own resources prove nonrenewable. the rise of john d. rockefeller’s standard oil, edison’s power grid, and the energy required to power them, haunt the novel and shape lily’s demise. one critic has gone so far as to suggest that floral imagery in the novel was planted in wharton’s mind by john d. rockefeller jr.’s notorious  speech, “the american beauty rose,” in which he asserted, the american beauty rose can be produced in the splendor and fragrance which bring cheer to its beholder only by sacrificing the early buds which grow up around it. this is not an evil tendency in business. it is merely the working out of a law of nature and a law of god. whether or not she had read rockefeller’s well-known speech or the extensive commentary it engendered, wharton deploys a similar darwinian logic and imagery in her novel with a far less salubrious outcome. lily “had been fash- ioned to adorn and delight; to what other end does nature round the rose-leaf and paint the humming-bird’s breast?” it will surprise no one that late nine- teenth-century republican ideology privileged material wealth over environ- mental health, yet wharton exposes the hypocrisy – or at least the blind spot – behind selden’s idealistic rhetoric of emancipation. lily is not free, but selden is also far more circumscribed than he imagines. the goal of cor- porate leaders such as john d. rockefeller sr. was to free not individuals but corporations not only from government regulation but also from the limits of nature. as the chief counsel of standard oil, s. c. t. dodd, said in , capital would make “all nature subservient to the human race” corporations such as standard oil convert nature into commodities. selden regards lily with a similarly reifying gaze, but lily herself understands nature only in terms of use-value, as, for instance, “a scene which was the fitting back- ground of her own sensations.” tarbell, whose father had been an independ- ent oil producer and refiner in titusville, pennsylvania, driven out of business and into debt by standard oil, exposed the unfairness of rockefeller’s highly efficient, monopolistic business practices. tarbell hated privilege and loved nature (and originally planned to become a biologist), yet she discovered, as  robert mcilvaine, “edith wharton’s american beauty rose,” journal of american studies, ,  (aug. ), –, .  wharton, house of mirth, .  quoted in wlasiuk, “refining nature,” .  wharton, house of mirth, .  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core she put it, that there was “a science of society as well as of botany.” though concerned about the exploitation of the earth’s resources, she saw it as a socio- economic, rather than an environmental, problem, concluding that “a trilogy of wrongs” had produced gross inequities: “discriminatory transportation rates, tariffs save for revenue only, and private ownership of natural resources.” as wlasiuk comments, however, “standard oil’s ‘structural power’ issued not only from the corporation’s influence in the political and economic context, but also from its dominion over nature, the source of all wealth.” lily bart dramatizes the externalities or hidden costs of such domin- ion. another wealthy suitor tells lily, in making his marriage proposal, “i should want my wife to be able to take the earth for granted if she wanted to.” such is the attitude of standard oil, which idealized the earth as avail- able for what appeared the most efficient human use, without accounting for environmental costs. property lines are not visible in the “pastoral distances.” but the republic-of-the-spirit chapter implies that to take the earth for granted is a problem. it takes the war against matter into the idealized landscape; “freedom” comes from the rational subjugation of nature, or aesthetic sublim- ation of the sensual. analogously, there must be a steep cost for lily to give herself away. the difference between pastoral heights, where lovers fantasize like children, and the “actual world” where motors appear, suggests ways in which mechanical energy converts itself into thought, or can seem at odds with serious thinking. later, after falling from grace, lily attaches herself to the nouveaux riches, “as carelessly as a passenger is gathered in by an express train.” wharton frames lily’s demise explicitly as a tragedy, with frequent references to the greeks, but lily does not have a moment of anagnorisis. she is simply “exhausted” in the end, and, most telling, she yearns “for that other luxurious world, whose machinery is so carefully concealed that one scene flows into another without perceptible agency.” lily’s failure, however, is the author’s opportunity. wharton’s subject is precisely the difficulty of making agency perceptible. where does energy come from? what effects does it produce? if, according to the first principle of thermodynamics, energy can be neither created nor destroyed, where does it go when work is performed or action completed? energy can change forms, and, as the metaphors of hidden machinery and imperceptible agency imply, it can flow from one place to another. wharton does not pretend to be a physicist or to intervene in questions of  robert c. kochersberger jr., ed., more than a muckraker: ida tarbell’s lifetime journalism (knoxville: university of tennessee press, ), xlvi.  wharton, house of mirth, .  ibid., . edith wharton’s resource aesthetics  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core science and engineering, but her narrative reflects a new, modern reality shaped by massive, invisible forces. she does not offer the technical or formal innova- tions of modernism – her fiction retains a sequential structure and omniscient narrator – but the house of mirth highlights what is occluded in the total visi- bility to which the conventional nineteenth-century novel aspired. from its opening in grand central station, with selden’s “surprise” at the sight of lily, to its conclusion at her deathbed, when the bewildered selden “felt that the real lily was still there, close to him, yet invisible and inaccessible,” the novel focusses on the limitations of individual points of view. the term “energy” signifies change, but it is often associated with metaphysics. as canadian scientist vaclav smil puts it, “energy is not a single, easily definable entity, but rather an abstract collective concept, adopted by nine- teenth-century physicists to cover a variety of natural and anthropogenic … phenomena.” we recognize energy in heat, motion, and light, but we also use energy in simply thinking about it. wharton extrapolates from the work of mechanics, applying it to any process that produces a change within an affected system. concealment of power sources – the invisibility of energy, yet its vital importance – indicates a central problem for characters in a novel, a genre pre- mised on novelty and on realism. the house of mirth turns on a duality of high and occluded visibility. “brilliant young ladies, a little blinded by their own effulgence,” the omniscient narrator remarks, “are apt to forget that the modest satellite drowned in their light is still performing its own revolutions and generating heat at its own rate.” the social blindness of young ladies, refracted here through metaphors of light and heat, and the resources that gen- erate these effects, speak to a broader set of assumptions. henry adams also recognized in new electric generators a kind of numinous, mysterious power analogous to the cult of the virgin in medieval europe, a theory he develops in “the dynamo and the virgin,” the most famous chapter of the education of henry adams. awestruck at the paris exposition of , adams found in the dynamo a symbol of infinity. as he grew accustomed to the great gallery of machines, the historian “began to feel the forty-foot dynamos as a moral force, much as the early christians felt the cross.” one might experience the chill produced by an air conditioner or the heat produced by an electric furnace, but energy, the cause of the effect, was “imperceptible to the senses.” for adams, new forms of energy posed a problem for the historian or any teller of stories, akin to the one wharton describes when “machinery is so carefully concealed that one scene flows into another without perceptible agency.” thus, adams  vaclav smil, energy: a beginner’s guide (london: oneworld, ), .  wharton, house of mirth, .  adams, education, .  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core “found himself lying in the gallery of machines at the great exposition of , his historical neck broken by the sudden irruption of forces totally new.” wharton relates “forces totally new” to social change and an evolving worldview. take the social significance of natural gas in her novels. for much of the nineteenth century, natural gas was used as a source of light (the first well was dug in ), but it was difficult to transport without pipelines, which only began to be constructed in a major way in the s, when gas was already giving way to electric lighting. so, here too paying atten- tion to an energy resource in the novel can illuminate aspects of ideology. for instance, at the turn of the century the mansion of mrs. peniston is still lit by gas rather than electricity, one sign of her unproductive conservatism. the domestication and aestheticizing of electricity had been promoted among wealthy new yorkers since the s. alice gordon’s  book decorative electricity, for instance, “showed well-to-do ladies how to transform their homes into elegant apotheoses of indirect and romantically installed illumin- ation.” the first explicit reference to miss peniston’s gaslight appears in a scene that literally sheds light on a worker to whom lily has been all but blind, the charwoman, mrs. hansen, who comes to bribe her with a letter found in selden’s garbage: “the glare of the unshaded gas shone familiarly on her pock-marked face.” lily purchases the letter and returns to her room, where she “immediately turned up the gas-jet and glanced toward the grate.” she had planned to burn the letter, thinking of selden’s reputation, but she does not, regarding it too as a potential resource of her own rehabili- tation. the point is not that turning on the gas is a problem or wasteful but that attention must be paid to both the literal and figurative “machinery” that has been so carefully concealed. forms of energy, like personal resources, may not be perceptible, but the reader and characters can extrapolate from their effects. when, in the end, lily is beyond hope, alone beneath the white glare of an electric streetlamp, she is discovered by a young woman her charity had helped, a survivor now married to a “motor-man.” lily allows herself to be taken to the young woman’s apartment, which proves a momentary refuge. there, natural gas proves a comfort, an escape from the harsh electric lighting of the urban jungle. as historian of science graeme gooday comments, “much of the early cultural anxiety about electricity centered on the female body, specifically threats to its physical safety and aesthetic appearance.” this single gas jet  ibid., .  graeme gooday, domesticating electricity: technology, uncertainty and gender, – (london: pickering & chatto, ), .  ibid., . edith wharton’s resource aesthetics  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core implies nostalgia for the home lily has lost, along with the “making of pros- perous homes” central to roosevelt’s logic of prudent resource use. “nettie struther’s match” makes “a flame leap from the gas-jet above the table,” revealing the kitchen to lily “as extraordinarily small and almost miraculously clean.” nettie’s domestication of energy, channeling in the home the product of forces that had left henry adams in awe, reflects her own socioeconomic progress and that of american culture, even as it signals the homeless lily’s demise. between  and , global energy use exploded, driven by demand for fossil fuels. in these years consumption of coal, petroleum and natural gas in america more than doubled. in , the supreme court ruled that standard oil was an illegal monopoly and ordered it to be broken into many smaller companies (the biggest of which became exxon), which fueled competition and, with production of the model t, accelerated use. this indus- trial history is immediate background for the custom of the country, which is full of the language of monopoly in business and in love (e.g. “there was nothing of the monopolist about mabel, and she lost no time in making undine free of the stentorian group and its affiliated branches”). wharton’s novel of comparative customs, economies, and cultural norms centers on undine spragg’s energy and her insatiable appetite for resources. her father’s fortune is built on the exploitation of natural resources (and on the invention of a hair-waver for which undine, whose name means “wave,” was named). the spraggs’ first two children died from contaminated water, which prompted her father to develop a “pure water” reservoir, along with a power station at the apex water-works; this development in turn enabled him to capitalize on real estate in apex (a fully capitalized city upon a hill) before moving to new york to enhance his daughter’s social chances, as mining interests and railroads take over apex, leading to the mon- opolistic apex consolidation company. unlike her father, who grows increas- ingly weary, undine never stops moving; she is the embodiment of the new fossil-fuel economy. “custom” is organized around particular energy resources, and her desires illuminate the society’s energy unconscious. for example, she is disappointed at her first dinner party among old-money new york by the way in which it is lit and heated: “instead of a gas-log, or a polished grate with elec- tric bulbs behind ruby glass, there was an old-fashioned wood-fire.” undine’s beauty is the mirror image of lily’s, but her career is the inverse. unlike lily,  independent statistical analysis, us energy information administration, at www.eia.gov/ totalenergy/data/annual/showtext.php?t=ptb; world energy consumption since  in charts, https://ourfiniteworld.com////world-energy-consumption- since--in-charts, accessed  july .  wharton, custom of the country, .  ibid., .  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core http://www.eia.gov/totalenergy/data/annual/showtext.php?t=ptb http://www.eia.gov/totalenergy/data/annual/showtext.php?t=ptb https://ourfiniteworld.com/ / / /world-energy-consumption-since- -in-charts https://ourfiniteworld.com/ / / /world-energy-consumption-since- -in-charts https://ourfiniteworld.com/ / / /world-energy-consumption-since- -in-charts https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core who can seem at harmony within a pastoral landscape, undine, sitting under the wisteria in central park, is conscious of “blazing out from it inconveni- ently.” if lily is the virgin, undine is the dynamo. undine is as inexhaustible as an energizer bunny, consuming anyone and anything that lies in her path, starting with the “desultory” ralph marvell, who was raised for a life of “cultivated inaction.” unfit for the modern world, he is (more like lily) an object of conspicuous consumption for the par- venue. in ralph’s family, “material resources were limited on both sides of the house, but there would always be enough for his frugal wants.” ralph is like a run-down motor, and “when he came home at night the tank was empty” the application of the empty-tank metaphor to a human being indicates the degree to which fossil fuels alter the very conception of humanity. using up one husband, his wife, whose parents wonder “whence undine derived her overflowing activity,” simply turns to another. undine is the resourceful character par excellence; a “monstrously perfect result of the system.” like lily, her beauty is her principal power source, and she capita- lizes on it with a vengeance, cashing in for marriage after marriage after mar- riage – a pursuit of happiness that privileges pursuit over happiness and promises to go on after the novel’s final line, which gestures at “something that neither beauty nor influence nor millions could ever buy for her.” after the divorce, ralph recalls her beauty “no longer as an element of his being but as a power dispassionately estimated.” at the thought of their mar- riage, one friend recognizes that “poor ralph was a survival” of the pre- industrial age, “and destined, as such, to go down in any conflict with the rising forces.” while lily bart had the idealistic slogan “beyond” printed on her stationery, the custom of the country shows that nothing is beyond undine. incapable of economy, undine moves to paris, back to new york, to paris again, to reno (for a divorce), and so on. she bears ralph’s son, is distracted by every novelty, spends a fortune (largely her father’s), and turns to other men. undine refuses to be bothered by what selden called “material accident,” but she is hardly what he had in mind as a success. for her, freedom (such as it is) requires the massive unleashing of the productive powers of capitalism, not an aesthetic transfiguration of material life but an occlusion of its unregeneracy: “her senses luxuriated in all its material details: the thronging motors, the bril- liant shops … the noise, the crowd, the promiscuity beneath her eyes symbo- lized the glare and movement of her life.” mechanical energy has been converted to thought. the proliferation of technology has altered the life of  ibid., .  ibid., .  ibid., .  ibid., .  ibid., .  ibid., .  ibid., .  ibid., . edith wharton’s resource aesthetics  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core the spirit. ubiquitous motors are among its vehicles: “as the motor flew on through the icy twilight, her present cares flew with it.” nothing raises undine’s spirits better than a daily drive in a motor, which is literally what the doctor orders when material cares assail her. after ralph commits suicide, undine marries the marquis raymond de chelles, but finds herself unhappily torn between the city of light, specifically the nouveau luxe fre- quented by international high flyers, and his rural estate, pointedly named saint désert, to which undine finds herself largely confined. she chafes under “considerations of economy,” as her aristocratic husband applies scien- tific principles of forestry and agriculture in the hope of turning a profit, while his feckless younger brother, to undine’s dismay, gets to renovate the piping, heating, and illumination of their parisian hôtel. at the chateau undine per- sonifies gratuitous energy consumption that refuses to be checked, finding sat- isfaction in “having fires lit in both monumental chimneys” solely to provoke the elderly marquise: “never before in the history of saint désert had the con- sumption of fire-wood exceeded a certain carefully-calculated measure; but since undine had been in authority this allowance had been doubled.” refusing to be constrained, undine epitomizes many “customs” that wharton loathed, but the recently divorced author also clearly admires her energy and even identifies with her, giving undine her own nickname, “puss.” finally, undine marries the “railroad king,” and her divorce is “rail- roaded” through the courts, literally and figuratively, as judge and happy couple hastily board moffatt’s special together. that undine leaves chelles and weds moffatt, who with the success of the apex consolidation scheme now owns all of apex, allegorizes not only the incorporation of america but also the marriage of resources and aesthetics. moffatt is an aesthete as well as industrialist, and undine’s beauty satisfies his sensuality. she yields to his will, as (in emerson) the earth does to the plastic eye, and “her energies revived like plants in water.” wharton was not a critic of the new fossil-fuel economy, though elements of critique appear in her work. ambivalent, she gave voice to the fascination and pleasures of energy innovations and alarm at their consequences. in a  letter she expressed wonder at getting out of her “motor” in paris and looking up into the air to see an aeroplane, high up against the sky … and it was the comte de lambert in a wright bi-plane, who had just flown across from juvisy – and it was the first time that an aero- plane has ever crossed this great city!! think “what soul was mine” – and what a setting in which to see one’s first aeroplane flight!  ibid., .  ibid., .  ibid., .  letters of edith wharton, .  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core wharton shared in the exhilaration of the petro-culture of speed and power, and her nostalgia for the slower, horse-drawn new york of her youth is shaped by the realization that it is irretrievable. in her autobiography, however, she speaks of the “growing sense of the waste and loss” during world war i con- nected to new uses of aeroplanes in battle, which explained, in part, why she turned to the world of her childhood (the s) in the age of innocence. to sara norton, the recipient of the letter enthusing about the wright biplane, she writes of the “turmoil and mediocrity of today.” yet her ambivalence about new forms of energy and the social changes they cause shapes her work’s form and themes. above – or beneath – all, wharton recognized what to others had been hidden in plain sight, that energy is the inescapable condition and context for all forms of culture. the transatlantic steamer in custom is the semantic, suggesting a relationship between modern transportation technology and the construction of meaning. wharton and henry james playfully named her cars after authors (george sand and alfred de musset). from its opening, when the sight of lily in grand central station refreshes selden’s eyes, to the moment lily blows out her final candle, the house of mirth reflects on the human and natural resources fueling culture. the same is true of the luminous, throbbing, motorized world that charges undine spragg’s adventures and of her refusal to be limited by “considerations of economy.” appearing almost precisely between publication of the house of mirth and the custom of the country, f. t. marinetti’s “manifesto of futurism” opened with an exhort- ation to sing “l’abitudine all’energia” (the habit of energy), to exalt “l’insonnia febbrile” (feverish insomnia, which is what dooms lily), and “violente lune elettriche” (violent electric moons); he urged artists to celebrate the man at the wheel, the obliteration of time and space, to glorify smoking factories, the speed of automobiles, locomotives, and aeroplanes. “young and strong” futurists, he declared, wanted no part of the past, and in this respect they sound like earlier americans, from franklin to emerson and whitman. though she loved emerson and, especially, whitman, wharton was not of marinetti’s vanguard; she was a conservative, at least in manners and literary style. like henry adams, her feet were planted in an earlier century. yet, like adams too (who called himself a “conservative anarchist”), wharton’s dismay at the rapidity of change made her a careful student of it, and there is no escap- ing – in both adams and wharton – an appreciation of what it took to succeed in the high-energy culture. and wharton did succeed. after ,  wharton, a backward glance, –.  quoted in lewis, edith wharton, .  f. t. marinetti, “fondazione e manifesto del futurismo,” at www.gutenberg.org/files/ /-h/-h.htm, accessed  july . edith wharton’s resource aesthetics  terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core http://www.gutenberg.org/files/ / -h/ -h.htm http://www.gutenberg.org/files/ / -h/ -h.htm https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core thanks in part to royalties from the book, wharton purchased increasingly elaborate vehicles for “motor-flights” in new england and france. her  travelogue, a motor-flight through france, opens complacently, “the motor-car has restored the romance of travel.” henry james, who loved these rides, gushed to his brother william, “i greatly enjoyed the whole lenox countryside, seeing it as i did by the aid of the whartons’ strong com- modious new motor, which has fairly converted me to the sense of all the thing may do for one and one may get from it.” to wharton, he wrote of the house of mirth, “i wish we could talk of it in a motor-car.” author biography alan ackerman is a professor of english at the university of toronto. his books include just words: lillian hellman, mary mccarthy, and the failure of public conversation in america (), seeing things, from shakespeare to pixar (), and the portable theater: american literature and the nineteenth-century stage ().  edith wharton, a motor-flight through france (new york: charles scribner’s sons, ; first published ), .  james, letters of henry james, volume iv, .  alan ackerman terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core 	edith wharton's resource aesthetics and the dawn of the american energy crisis microsoft word - paper_ v _kalirasu.doc the annals of “dunarea de jos” university of galati fascicle iii, , vol. , no. , issn - x electrotechnics, electronics, automatic control, informatics this paper was recommended for publication by emil ro u practical implementation of embedded controlled boost converter for solar installation system a. kalirasu, s. s. dash research scholar, satyabhama university, chennai, india professor,srm university,chennai, india. email: akalirasu@yahoo.co.in abstract: the solar photovoltaic power has received great attention and experienced impressive progress in the countries all over the world in recent years because of more and more serious energy crisis and environmental pollution. this paper proposes a embedded controlled boost converter for solar installation system. boost converter system is simulated using matlab and it is implemented using embedded controller. the simulation and experimental results of this system are presented and compared. this converter has advantages like improved power factor, fast response and reduced hardware. keywords: embedded controller, boost converter, solar cells, pv cells. . introduction with the rapid depletion of the conventional fossil fuels, energy crisis and environment pollution become more and more serious. in recent years, much effort has been made to find renewable clean energies, and solar energy has become a promising alternative source because it has many advantages such as abundance, pollution free and renew ability. the solar photovoltaic (pv) power will play an important role in alleviating the energy crisis and reducing the environmental pollution and has a bright prospect of applications. the output voltage generated by the photovoltaic arrays, the fuel stacks, the super capacitors or the battery sources is relatively low, it should be boosted to a high voltage. how to realize high step-up dc/dc converters with high performance is one of the main issues in the renewable energy applications. the limitations of the conventional boost converters are analyzed and the conceptual solution for high step-up conversion is proposed in this paper. then the state-of-the-art topologies are covered and classified based on the circuit performance. the challenges in high step-up renewable energy applications are summarized to generate the next generation high step-up dc/dc converters. dc-dc converters are used in renewable energy systems to step up the low battery or electric storage devices voltage to high voltage levels required by the loads. some of the main factors to look for while designing dc converters for solar energy systems are the gain, output power and the ease of design. the conventional step up converters are not provide the required gains even with maximum duty cycles [ ]. other topologies such as flyback converters also suggested. however they cannot be used in energy systems as they have low power ratings below watt [ ] as a result, modified boost designs such as the half and full bridge converters can be used. by looking at the disadvantages of these converters, one can see that they lack the ease of design factor and have lower efficiencies due to the use of transformers [ ]. the annals of “dunarea de jos” university of galati fascicle iii, , vol. , no. , issn - x as a result, new super-lift techniques are applied in the converters design. the advantage of these techniques is the increases in the stage-by-stage voltage transfer gain in geometric progression [ ]. modeling and control of a cascaded boost converter with a single switch is discussed [ ]. the above literatures does not deal with the embedded implementation of boost converter system for solar installation. the limitations of the conventional boost converters are analyzed and the conceptual solution for high step-up conversion is proposed in this paper. this work makes an attempt to implement the boost converter using c controller. . solar cell system the density of power radiated from the sun (referred to as the “solar energy constant”) at the outer atmosphere is . kw/m .the final incident sun light on the earth surface has the peak density of kw/m at noon in the tropics. the technology of photovoltaic (pv) is essentially concerned with the conversion of this energy into usable electric form. the basic element of the pv system is the solar cell. solar cell can convert the energy of sunlight into electricity directly. a simplified equivalent circuit of a solar cell consists of a current source in parallel with a diode variable resistor connected to the solar cell generator as a load. the relationship between the current and voltage may be determined from the diode characteristics equation: i = iph – io (e qv/kt - ) = iph – id ( ) where q is the electron charge, k is the boltzmann constant, iph is the photocurrent, io is the reverse saturation current, id is the diode current and t is the solar cell operating temperature (k). the stand-alone photo-voltaic energy system requires storage to meet the energy demand during period of low solar radiation and night time. the battery storage in a solar system should be properly controlled to avoid catastrophic operating condition like over charging or frequent deep discharging. storage batteries account for the most pv system failures and contribute significantly to both initial and the eventual replacement cost. charge controllers regulate the charge transfer and prevent the battery from being excessively charged and discharged. switch mode dc to dc converters are used to match the output of a pv generator to a variable load. the dc to dc converters allow the charge current to be reduced continuously in such a way that the resulting battery voltage is maintained at a specified value. a practical photovoltaic energy conversion system block diagram is shown in fig. . the equations of boost converter are as follows: the average output voltage is given as, vo(avg) = vs / ( -d) ( ) the ripple in output voltage is given as, vo(ripple) = io(avg) d / fc ( ) and the ripple in output current is given as, io(ripple) = vsd / fl ( ) where vs is the input voltage, d is the duty cycle ratio l is the inductance and f is the frequency of the boost converter. boost inductor and capacitor are calculated using the formula l = vod / fio ( ) c = d / fr ( ) fig. . block diagram of pv installation system . simulation results simulation is done using matlab and the results are presented. boost converter for solar installation system is shown in fig a. pv array is represented as a dc source. the dc input voltage is shown in fig b. the driving pulses of the mosfet are shown in fig c. the voltage across the mosfet is shown in fig d. the voltage across the mosfet is complement of the input. the output current is shown in fig e. the ripple can be reduced by using a large value capacitor. the dc output voltage is shown in fig f. dc output takes long time to settle due to the presence of filter capacitor. the output voltage reaches v. the closed loop system is shown in fig a. output voltage is sensed and it is compared with a reference voltage. the error is processed by a pi controller. the output of pi controller adjusts the pulse width to maintain the output voltage constant. input voltage and output voltage of closed loop system is shown in fig b. the output voltage reduces and reaches the set value. the annals of “dunarea de jos” university of galati fascicle iii, , vol. , no. , issn - x data used for simulation studies are as follows: input voltage v output voltage v lf μh cf μf rl ton . ms toff . ms fig. a. simulink circuit of solar installation system fig. b. input voltage fig. c.driving pulses fig. d. voltage across the switch fig. e. output current fig. f. dc output voltage fig. a. simulink circuit of closed loop solar installation system the annals of “dunarea de jos” university of galati fascicle iii, , vol. , no. , issn - x fig. b. input and output voltages . experimental results in order to verify the circuit operation and confirm the simulation results a prototype is built and lab tested. the embedded controller based driver circuit is shown in fig b. the output pulse from the controller are amplified using the driver chip ir . the hardware implementation is shown fig. a. the driving pulses applied to the mosfet are shown in fig c. the input voltage applied to the converter is shown in fig d. the input voltage is . v. the output voltage of the boost converter is . v.the oscillogram of input voltage is shown in fig e. display of output voltage is shown in fig f. the oscillogram of input voltage is shown in fig g. the output is free from ripple. from the figures c and c, it can be seen that the experimental results are almost similar to the simulation results. fig. a.hardware circuit u ir lo hohin shdn lin vss com vb vcc vdd vs e- d n u l /to vin vout e e y z tb m r k e m d n d n u l /to vin vout d n e sw sw pushbutton e- m e r k u ir lo hohin shdn lin vss com vb vcc vdd vs v f req = hz vampl = v e c e- e- c e- e- u at c rst/vpp vcc xtal xtal p . /ain p . /ain p . p . p . p . p . p . p . /rxd p . /txd p . /int p . /int p . /t p . /t p . v m d led c e- c e- v tx fig. b.control circuit fig. c.driving pulses fig. d.display of the input voltage fig. e. input voltage the annals of “dunarea de jos” university of galati fascicle iii, , vol. , no. , issn - x fig. f. display of the output voltage fig. g. output voltage . conclusion the limitations of the conventional boost converter in high step-up renewable energy applications are analyzed and a lot of topologies, which are published in previous papers, are summarized. from the above analysis, the major challenges in high step-up dc/dc converters are the following: :) how to extend the voltage gain and avoid the extreme duty cycle to reduce the current ripple and the conduction losses; :) how to reduce the switch voltage to make low voltage mosfet’s available; :) how to alleviate the output diode reverse-recovery problem; :) how to increase the power level easily and reduce the passive component size. this paper presents simulation and experimentation of embedded controlled boost converter system for solar installation system. matlab model for boost converter system is developed by using matlab / simulink. this converter has advantages like simple hardware and good output voltage regulation. the embedded controlled boost converter is capable of improving the voltage level from v to v. the experimental results closely agree with the simulation results references o. abutbul, a. gherlitz, y. berkovich, and a. ioinovici. ( ). step-up switching-mode converter with high voltage gain using a switched capacitor circuit. in: ieee trans. circuits syst.i, fundam. theory appl., vol. , no. , pp. – , aug. . i. barbi and r. gules. ( ). isolated dc–dc converters with high-output voltage for twta telecommunication satellite applications. in: ieee trans.power electron., vol. , no. , pp. – , jul. . f.l. luo and h. ye, ( ). positive output cascade boost converters. in: ieee proc.-electr. power appl., vol. , no. , september . morales-saldana, j.a., galarza-quirino, r., leyva- ramos, j., carbajal-gutierrez, e.e.;ortiz-lopez, m.g. ( ). modeling and control of a cascaded boost converter with a single switch. in: iecon - nd annual conference on ieee industrial electronics, pp. – , nov rashid m. ( ). power electronics: circuits, devices and applications. pearson education international, . rong-jong wai, wen-hung wang, and chung- you lin ( ), high- performance stand-alone photovoltaic generation system. in: ieee transactions on industrial electronics, vol. , no. , pp. - , january . a.kalirasu has received b.e. degree in electrical and electronics engineering from madurai kamaraj university, madurai, india in the year of . he has received m.e. degree in power electronics and industrial drives engineering from sathyabama university, chennai, india in the year of . he is a research scholar in sathyabama university, chennai, india. he has years of teaching experience his current research interest is on solar systems. dr.s.s dash is working as a professor in srm university, chennai, india. he has years of teaching and research experience. he has received m.e. degree in power system engineering from university college of engineering, burla, india in the year of . he obtained phd in electrical engineering from anna university, chennai, india in the year . his current research interest includes facts, drives, ai techniques and power electronic converters. fep- -editorial .. editorial ya-ling he, ruzhu wang, anthony paul roskilly, peiwen li efficient use of waste heat and solar energy: technologies of cooling, heating, power generation and heat transfer © higher education press and springer-verlag gmbh germany as a research focus, energy conservation has attracted a great deal of attention in recent years due to the energy crisis and environmental pollution concerns. many countries made great efforts on both research and implementing energy conservation technologies. cur- rently more than % of the total world’s delivered energy is consumed by industry and about one sixth of the total energy consumed is wasted as low-grade heat, for example through radiation loss, exhaust gas flows, and cooling fluid circuits. therefore, the recovery and reuse of waste heat is an effective way to significantly improve energy utilization. in addition, solar energy can provide low grade heat and is a clean and renewable form of energy. the efficient use of low grade heat from these sources can play an important role for a large number of applications. thermal driven cooling, heating and power generation technology provides a means to practically and effi- ciently use low grade heat. performance improvement, flexible operation of hybrid systems, and low capital and operating costs are necessary to ensure low grade heat recovery and reuse technologies are attractive to end users. in this thematic special issue, seven invited papers contribute new research and knowledge on optimized cycles of heating, cooling and power genera- tion, as well as the feasibility for waste heat reuse. four papers focus on the development of solar systems. a high temperature heat pump is an efficient technology to upgrade waste heat or reuse by the industrial processes. z.y. xu and his coworkers produce a comprehensive review of thermally driven absorption heat pumps for different applications, including heat amplification and temperature lift cycles, working pairs and current projects. they conclude that large tempera- ture lift heat pumps and open-cycle absorption heat transformers, with direct contact with exhaust gas, should be further studied and developed. organic working pairs with good stability, no corrosion and good thermophysical properties are necessary to be studied. h.s. bao and her coworkers propose a hybrid absorption-compression, high temperature heat pump for the recovery of industrial waste heat of °c– °c. the cycle allows a flexible operation with energy input from waste heat and electrical power. the study gives a numerical analysis and several features such as recirculation flow ratio are presented. b. hu and his colleagues present an exergy analysis for a multi-stage compression heat pump used for high temperature heating applications with r ze(z) as the refrigerant, which has a low gwp value. the analysis is conducted on the basis of producing pressurized water at °c under different waste heat conditions. single, double and three stage compression heat pumps are compared and this indicates a multi-stage compression heat pump has less power consumption. a three-stage compres- sion heat pump system has obvious advantage of higher exergy efficiency. in addition to absorption and com- pression heat pumps, a chemical heat pump provides another way of upgrading heat with a large temperature lift. m. xu and his coworkers carry out an exergy received nov. , ; online dec. , ya-ling he (✉) school of energy and power engineering, xi’an jiaotong university, xi’an , china e-mail: yalinghe@mail.xjtu.edu.cn ruzhu wang (✉) school of mechanical engineering, shanghai jiao tong university, shanghai , china e-mail: rzwang@sjtu.edu.cn anthony paul roskilly (✉) sir joseph swan centre for energy research, newcastle university, newcastle upon tyne ne ru, uk e-mail: tony.roskilly@ncl.ac.uk peiwen li department of aerospace and mechanical engineering, the university of arizona,tucson az , usa front. energy , ( ): – https://doi.org/ . /s - - -z analysis on an isopropanol-acetone-hydrogen chemi- cal heat pump which can upgrade waste heat of °c– °c to °c. the highest irreversibility is in the distillation column and reactive distillation is an effective alternative. the operating conditions could be optimized to obtain greater thermodynamic performance. besides using heat pump technology, waste heat can be converted to produce cooling and electrical power. y. lu and his coworkers present a simulation study for a kw organic rankine cycle using a scroll expander to recover waste heat from the cooling system and exhaust gas of an engine. they pointed out a potential solution to fully recover engine coolant energy with the penalty of reduced orc thermal efficiency. the proposed solution has the advantages of higher power output and less rejected heat from the engine radiator compared with that of the engine orc system only using the coolant energy as preheat source. a recuperator is suggested to be added to the orc system when the working fluids are isentropic or dry types. when the engine is operated under rated power condition, the integrated waste heat recovery system can potentially improve the overall system performance by . %. j. cho and his coworkers develop a small-scale, multi- purpose experimental s-co system using a high- speed radial-type turbo-generator. a preliminary experi- ment test is conducted using r a as a working fluid to determine the operational characteristics of the closed rankine cycle. a turbine power of w is successfully generated. p. gao and his colleagues propose a solid sorption combined cooling and power system using the waste heat from the exhaust gas of a vehicle. the cogeneration system uses mncl /cacl -nh working pairs and its feasibility is demonstrated experimentally. for solar systems, heat collection and heat transfer issues are important to improve system performance and to make system operation reasonable and stable. s. tang and his colleagues review different approaches for solar fuel production from spectrum-selective photo- thermal synergetic catalysis. the meaning of synergetic effects, the mechanisms of spectrum-selectivity and photo-thermal catalysis are introduced and a number of experimental or theoretical works are sorted by the chemical reactions and the sacrificial reagents applied. the studies are summarized based on the operating conditions, spectrum-selectivity, materials and produc- tivity. they suggest that the optimizations on materials and structure of catalysts and deeper understanding of the reaction mechanism, especially the photo-thermal synergy effects are necessary to be given more academic attentions. on the performance of direct steam generation solar power tower plant, y. luo and his coworkers study the impacts of solar multiple and thermal storage capacity, which are two key design parameters for the sensitivity analysis of the annual plant performance and the economic assessment. the analysis gives the effects of site, solar field equivalent electricity size and investment costs on the minimum levelized cost of electricity, optimal solar multiple and thermal storage capacity, which is based on the reference cases. t.j. wang and his colleagues present an experimental study on a quartz tube falling particle receiver. silicon carbide particles are proposed to be the heat transfer fluid when the temperature is higher than °c in which case molten nitrate salt becomes chemically unstable. particle receivers have the poten- tial to increase the maximum temperature of the heat- transfer media to over °c. experiments are carried out to test the dynamic thermal performance of the receiver. the experimental study focuses on the effect of particle diameter, particle inlet temperature, particle flow rate and type of the quartz tube on outlet particle temperature. it provides a novel strategy for the development of a high temperature heat transfer fluid. b.j. lougou and his coworkers conduct a numerical analysis of radiation heat transfer and temperature distributions for a solar thermochemical reactor used for syngas production. finite volume discrete ordinate method and p approximation for radiation heat transfer are employed. the study reveals that the temperature drop due to the boundary radiation heat loss could not be neglected for the thermal performance analysis of the solar thermochemical reactor. we hope these papers will provide you with a good overview of the technologies which can be utilized for the efficient use of waste heat and solar energy. the coverage is limited but we hope that it inspires more research exploration in this extremely important field. editor’s bio sketches: dr. ya-ling he is a chair professor at xi’an jiaotong university and the aca- demician of chinese academy of sciences. currently, she is the vice president of chinese association of refrigeration and the chairman of aca- demic committee of xi’an jiaotong university. in , she was rewarded the science and technology awards of the ho leung ho lee foundation. she is also a chief scientist for the national basic research program ( project) of china, an associate editor of applied thermal engineering and a member of the scientific council of ichmt. she was also the vice president of commission b - international institute of refrigeration. she has published about sci journal papers with a total citations more than times. her major interests are in the following fields: energy-saving theories and new methods in efficient utilization of energy, development and utilization of new energy, new energy storage technologies, advanced refrigeration and cryogenic techniques in high-tech fields, capture, control and utilization of front. energy , ( ): – co in energy and power system, fluid flow and heat transfer in micro systems, numerical principle and its applications in fluid flow and heat transfer processes, and thermal science problems in aeronautical and aerospace engineering. e-mail: yalinghe@mail.xjtu.edu.cn dr. ruzhu wang is chair professor and director of the institute of refrig- eration and cryogenics at shanghai jiao tong university. he graduated from shanghai jiao tong university in and with bachelor and master degrees. he received a ph.d from shanghai jiao tong university in . he had been appointed as the director of institute of refrigeration and cryogenics, shanghai jiao tong university since . currently he is also the director of engineering research center of solar energy, moe china. he has published over sci journal papers, with more than citations. he has written books on refrigeration technologies and solar energy. his major research contributions are in adsorption refrigeration, heat pumps, cchps and solar energy systems, heat transfer to superfluid helium, and green building energy systems. due to his most noteworthy contributions to refrigeration globally, he was honored to receive the j & e international gold medal from the institute of refrigeration in . e-mail: rzwang@sjtu.edu. cn professor (dr) a.p. roskilly is direc- tor of the sir joseph swan centre for energy research at newcastle univer- sity, uk. he is an associate director of the uk centre for energy systems integration, an associate member of the interdisciplinary centre for storage, transformation and upgrading of ther- mal energy (i-stute), a member of the science board of the energy storage supergen hub, and the national contact for the european energy research alliance joint programmes on energy efficiency in industrial pro- cesses (eeip) and energy systems integration (esi). profes- sor roskilly has published over sci journal articles in the past years and has received almost citations for his research papers over this period. he has performed a number of academic journal editorial roles and is currently an associate editor of applied energy. professor roskilly has years’ experience in the design, control, and operational optimisation of energy systems. his personal research group undertakes fundamental and applied research into various aspects of power generation and thermal energy systems including technology development and environmental impact assess- ment of alternative fuels for thermal power plants; combined heat and power systems; tri-generation; thermal power system configurations, chemisorption and pcm storage system development. e-mail: tony.roskilly@ncl.ac.uk dr. peiwen li is a full professor in department of aerospace and mechan- ical engineering at the university of arizona, usa. he obtained his ph.d. focused on thermo-science for energy and power engineering from xi’an jiao- tong university , china. he is asme member since . his recent research work focuses on thermal energy storage technologies, property measurement and evaluation of high temperature heat transfer fluids for solar thermal energy application, electrochemical and heat/mass transfer processes in fuel cells and electrolysis cells, fuel processing and reforming for hydrogen production, and heat transfer and fluid flow in industrial processes. his team has developed high temperature (up to °c) thermal storage and heat transfer fluids for concentrated solar thermal power systems. he has authored/co-authored one book, book chapters, peer reviewed journal articles and peer- reviewed conference articles. he is an active associate editor of journal solar energy and aims journal of energy. ya-ling he et al. efficient use of waste heat and solar energy << /ascii encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (none) /calrgbprofile (srgb iec - . ) /calcmykprofile (iso coated v % \ eci\ ) /srgbprofile (srgb iec - . ) /cannotembedfontpolicy /error /compatibilitylevel . 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d > /deu <feff a f f f e f f c c e d f c f f e c e e d e d c d d d c f e e f e c f a f f f f e e e e f d d f e c f e c e f f c f f f f e c e f f c e f c f a f d f e e> >> >> setdistillerparams << /hwresolution [ ] /pagesize [ . . ] >> setpagedevice low-oxygen response is triggered by an atp-dependent shift in oleoyl-coa in arabidopsis low-oxygen response is triggered by an atp- dependent shift in oleoyl-coa in arabidopsis romy r. schmidta, , martin fuldab, melanie v. paulc, max andersa, frederic pluma, daniel a. weitsa, monika kosmaczd, tony r. larsone, ian a. grahame, gerrit t. s. beemsterf, francesco licausig,h, peter geigenbergerc, jos h. schippersa, and joost t. van dongena, ainstitute of biology i, rheinisch-westfälische technische hochschule aachen university, aachen, germany; balbrecht von haller institute of plant sciences, goettingen university, goettingen, germany; cdepartment biology i, ludwig maximilian university of munich, planegg-martinsried, germany; dmax planck institute of molecular plant physiology, potsdam, germany; edepartment of biology, university of york, heslington, yo dd york, united kingdom; fintegrated molecular plant physiology research group, university of antwerp, g.u. , antwerpen, belgium; gplantlab, institute of life sciences, scuola superiore sant’anna, pisa, italy; and hdipartimento di biologia,università di pisa, pisa, italy edited by julia bailey-serres, university of california, riverside, ca, and approved november , (received for review june , ) plant response to environmental stimuli involves integration of multiple signals. upon low-oxygen stress, plants initiate a set of adaptive responses to circumvent an energy crisis. here, we reveal how these stress responses are induced by combining (i) energy- dependent changes in the composition of the acyl-coa pool and (ii) the cellular oxygen concentration. a hypoxia-induced decline of cellular atp levels reduces long-chain acyl-coa synthetase activity, which leads to a shift in the composition of the acyl-coa pool. subsequently, we show that different acyl-coas induce unique molecular responses. altogether, our data disclose a role for acyl-coas acting in a cellular signaling pathway in plants. upon hypoxia, high oleoyl-coa levels provide the initial trigger to release the transcription factor rap . from its interaction partner acyl-coa binding protein at the plasma membrane. subsequently, according to the n-end rule for proteasomal degradation, oxygen concentration- dependent stabilization of the subgroup vii ethylene-response factor transcription factor rap . determines the level of hypoxia-specific gene expression. this research unveils a specific mechanism activating low-oxygen stress responses only when a de- crease in the oxygen concentration coincides with a drop in energy. low-oxygen stress | integrative signaling | acyl-coa | erfvii | acbp flooding contributes almost % to the worldwide cost anddamage to crops provoked by natural disasters ( ). due to heavy precipitation and concomitant waterlogging or flooding events in large areas of the world, climate change will cause plants to be even more frequently exposed to oxygen-limiting conditions (hypoxia) in the near future ( ). in plants, subgroup vii ethylene-response factor (erfvii) transcription factors act as key regulators of hypoxic gene expression ( – ). during nonstress conditions, the erfvii protein related to apetala . (rap . ) is seques- tered to the plasma membrane via direct interaction with acyl- coa binding protein (acbp) ( , – ). upon hypoxia, rap . is released from the plasma membrane and subsequently accumulates in the nucleus ( , , ). further, the stability of erfvii proteins is tightly controlled in an oxygen-dependent manner employing the cys branch of the n-end rule ( , ). that is, erfvii protein degradation is prevented under hypoxic conditions when n end rule-assisted degradation is impaired due to oxygen limitation ( ). although the homeostatic regulation of adaptive responses to low-oxygen stress in plants is well in- vestigated ( , , ), the identity of the initial trigger to release rap . from its membrane docking protein acbp remains unknown and the existence of multiple signal queues that are integrated into low-oxygen specific responses is likely ( ). acbps represent an evolutionarily conserved protein family found in escherichia coli, yeast, animals, and plants ( , ) and participate in the regulation of unbound acyl-coa levels by seques- tration and transportation of acyl-coas ( , ). the interaction between members of a protein family capable of reversibly binding acyl-coas with the erfvii proteins rap . ( , ) and rap . ( , ) provided a first indication that acyl-coas can be involved in the release of erfvii transcription factor protein during hypoxia. we elaborated this mode of action with experiments on rap . as a representative member of erfvii transcription factors. acyl-coas are intermediates in both lipid catabolism and anabolism. in the catabolic pathway, fatty acids are activated in the cytosol by acyl-coa synthetases before their trans- port into mitochondria or peroxisomes where β-oxidation occurs. in plants, lipid anabolism occurs through two pathways: de novo fatty acid synthesis takes place in plastids and the generated fatty acids can be incorporated into complex lipids within the plastid by the so-called prokaryotic pathway. alternatively, the fatty acid may be exported from the plastid to the cytosol to become substrate for the eukaryotic lipid biosynthesis pathway in the endoplasmic reticulum (er). transport of fatty acids from the plastid, through the cytosol into the er is mainly mediated via palmitoyl-coa (c : -coa) and oleoyl-coa (c : -coa) that are produced from palmitic and oleic acid by the enzyme long- chain acyl-coa synthetases (lacs) at the outer plastid membrane in root and shoot tissues ( – ). in addition significance to control adaptive responses to the ever-changing environ- ment that plants are continuously exposed to, plant cells must integrate a multitude of information to make optimal deci- sions. here, we reveal how plants can link information about the cellular energy status with the actual oxygen concentration of the cell to trigger a response reaction to low-oxygen stress. we reveal that oleoyl-coa has a moonlighting function in an energy (atp)-dependent signal transduction pathway in plants, and we provide a model that explains how diminishing oxygen availability can initiate adaptive responses when it coincides with a decreased energy status of the cell. author contributions: r.r.s., m.f., t.r.l., i.a.g., f.l., p.g., j.h.s., and j.t.v.d. designed research; r.r.s. coordinated the experiments; r.r.s., m.f., m.v.p., m.a., f.p., d.a.w., m.k., t.r.l., g.t.s.b., f.l., and j.h.s. performed research; r.r.s., m.f., m.v.p., t.r.l., i.a.g., g.t.s.b., p.g., j.h.s., and j.t.v.d. analyzed data; and r.r.s., j.h.s., and j.t.v.d. wrote the paper. the authors declare no conflict of interest. this article is a pnas direct submission. this open access article is distributed under creative commons attribution-noncommercial- noderivatives license . (cc by-nc-nd). data deposition: the data reported in this paper have been deposited in the gene ex- pression omnibus (geo) database, www.ncbi.nlm.nih.gov/geo (accession no. gse ). to whom correspondence may be addressed. email: roschmidt@bio .rwth-aachen.de or dongen@bio .rwth-aachen.de. this article contains supporting information online at www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental. published online december , . www.pnas.org/cgi/doi/ . /pnas. pnas | vol. | no. | e –e p la n t b io lo g y http://crossmark.crossref.org/dialog/?doi= . /pnas. &domain=pdf https://creativecommons.org/licenses/by-nc-nd/ . / https://creativecommons.org/licenses/by-nc-nd/ . / http://www.ncbi.nlm.nih.gov/geo http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=gse mailto:roschmidt@bio .rwth-aachen.de mailto:dongen@bio .rwth-aachen.de https://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental https://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental https://www.pnas.org/cgi/doi/ . /pnas. to their involvement in lipid metabolism, acyl-coas are also known to modulate the activity of numerous enzymes, ion channels, and transcription factors in animals and microorgan- isms ( ). examples of acyl-coas directly affecting transcription factor activity by functioning as ligands have been reported for humans (hnf- α) ( ) and e. coli (fadr) ( ). for plants, di- rect involvement of acyl-coas controlling transcription factor activity was not demonstrated yet, although an indirect regula- tory role has been suggested ( ). hypoxia has detrimental effects on the plant’s cellular ho- meostasis, in the first place, because oxidative phosphorylation in mitochondria is reduced, which ultimately leads to a decrease of the cellular energy charge. this results in atp-consuming met- abolic processes being attenuated, including fatty acid synthesis and processing ( ). consequently, the export of newly synthe- sized fatty acids from the plastid into the cytosol is affected, since the activation to acyl-coas is atp dependent ( , ). there- fore, an energy-related impact of hypoxia on acyl-coa levels in the cytosol is expected and investigated here. in this study, we reveal a combinatory signaling network by which the reduced energy level under low-oxygen stress is in- tegrated into the erfvii-dependent hypoxic signaling cascade. we show that dynamic responses of c : -coa and c : -coa levels to hypoxia constitute an early molecular trigger, leading to dissociation of the acbp:rap . complex thereby activating the molecular low-oxygen response cascade. we describe an in- tegrative signaling mechanism in which adaptive gene expression upon low-oxygen stress results from the specific combination of (i) low-energy triggered release of the transcription factor rap . from acbp as mediated by an acyl-coa signal; and (ii) low-oxygen dependent stabilization of the rap . protein according to the n-end rule of protein degradation. results c : -coa promotes dissociation of the acbp:rap . complex in vitro and in vivo. in arabidopsis, the erfvii transcription fac- tor rap . is constitutively expressed but sequestered at the plasma membrane by binding to acbp during normoxic con- ditions, while it accumulates in the nucleus under oxygen con- centrations below % (vol/vol) ( , ). the interaction domains of acbp and rap . were previously identified in arabi- dopsis ( , , ) and appear to be well conserved among plant species (fig. a and b), indicating that complex formation of both proteins is a general feature in plants. importantly, changing the expression of acbp affects tolerance to low oxygen ( ) (fig. c and d) similar to what was shown previously for rap . ( ). during hypoxia gfp-tagged acbp remains at the plasma membrane (fig. e), while gfp-tagged rap . was shown to accumulate in the nucleus upon hypoxia ( , ). this indicates that rap . dissociates from acbp before its relocation to the nucleus. consequently, the release of rap . from acbp is considered as a trigger that activates adaptive gene expression in response to hypoxia. to investigate if acyl-coas interfere with the interaction be- tween acbp and rap . , we performed an in vitro affinity assay (si appendix, fig. s ) in the presence of either oleoyl-coa (c : -coa), which is a preferred substrate for acbp , or palmitoyl-coa (c : -coa) that is not a strongly interacting agent ( , ). in vitro exposure of an acbp :rap . protein complex to c : -coa, but not c : -coa, significantly de- creased the binding affinity between the two proteins as indicated by the reduced ratio of flag-tagged acbp and cfp-tagged rap . protein (fig. a and b). apparently, interaction be- tween acbp and c : -coa reduces the binding capacity of acbp for the transcription factor rap . . to confirm that c : -coa–induced dissociation of rap . from acbp also occurs in vivo, we exposed detached leaves of plants expressing s:rap . -gfp to various acyl-coas under aerobic conditions. application of c : -coa, but not c : -coa or c : -coa, significantly induced nuclear accumulation of rap . -gfp, in- dicating that rap . was released from acbp in vivo after the application of c : -coa, but not of c : -coa (fig. c and d). translocation of rap . to the nucleus was previously described to occur during hypoxic conditions ( , ). therefore, we tested if application of acyl-coa to leaves might have induced hypoxia due to increased beta-oxidation or mitochondrial respiration. how- ever, no increase of the oxygen consumption rate by leaf tissue after treatment with acyl-coas was observed, indicating that our experimental treatment did not affect the oxygen concentration of the tissue in this experiment (si appendix, fig. s ). we concluded, remobilization of the transcription factor rap . from the plasma membrane into the nucleus can be triggered in vivo by increasing the level of c : -coa. acyl-coas provoke distinct transcript responses. to determine if specific transcriptional responses are provoked by the applica- tion of different acyl-coas, rna-seq transcriptome analysis was performed on wild-type seedlings exposed to either mm c : - coa, c : -coa, or c : -coa. uptake of these externally applied acyl-coas is mediated by abcd transporters that first cleave the coa group from the acyl chain, allowing the resulting fatty acid to cross lipid membranes. once inside the cell, coa is immediately reattached, which traps the acyl-coa in the cellular compartment in which it has been imported ( ). this analysis revealed that each of these acyl-coas modulates distinct sets of genes (fig. a and dataset s ). the high specificity of induced changes in gene expression underlines the eligibility of acyl-coas as signaling molecules in plants. to investigate the biological function of the differentially regulated genes, a gene ontology (go) enrichment analysis ( ) was carried out. while applica- tion of c : -coa or c : -coa mainly affected the expression of genes related to reproductive development and hormone signaling, c : -coa mainly modulated the expression of genes associated with hypoxia and low-oxygen responses (fig. b and dataset s ). this result was confirmed by qpcr-assisted ex- pression profiling executed on wild-type plants incubated with c : -coa. indeed, rap . -regulated hypoxia-response genes were induced by c : -coa treatment, while c : -coa and c : -coa had only minor effects on the expression of these genes (fig. c and si appendix, table s ). this observation is readily explained by our earlier observation that rap . reloc- alizes to the nucleus upon c : -coa application (fig. c and d). therefore, it is concluded that c : -coa provides a specific cellular signal that is substantially involved in the control of gene expression by releasing rap . from acbp . increase of c : -coa to c : -coa ratio induces hypoxic gene expression in vivo. in a physiological context, c : -coa–mediated dissociation of rap . from acbp only makes sense when the endogenous acyl-coa pool responds to hypoxia. indeed, hplc- assisted quantification of acyl-coas revealed a shift to elevated c : -coa (fig. d) and c : -coa (si appendix, fig. s ) levels with less c : -coa (fig. e) after h of hypoxia, while no sig- nificant changes of the total pool of acyl-coas included in our analyses were observed (si appendix, fig. s ). these dynamic re- sponses of specific acyl-coas to changing environmental conditions as exemplified here for hypoxia are in line with the suggestion that acyl-coas in plants can play a role in stress signaling. a similar shift of the acyl-coa pool as observed during low- oxygen conditions was observed in transgenic plants in which two lacs genes, lacs and - , were knocked out ( ) (fig. f and g and si appendix, fig. s ). under aerobic conditions, lacs lacs double knockout plants have elevated c : -coa and reduced c : -coa levels. to provide further proof that endogenous changes of the c : -coa or c : -coa level can have an effect on low-oxygen responses of plants, we tested the induction of hypoxic e | www.pnas.org/cgi/doi/ . /pnas. schmidt et al. https://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental https://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental https://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental https://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental https://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental https://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental https://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental https://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental https://www.pnas.org/cgi/doi/ . /pnas. gene expression in lacs lacs plants in air. indeed, many rap . - dependent hypoxia-response genes were activated under aerobic conditions in lacs lacs (fig. h and si appendix, table s ). in addition, also tolerance to hypoxia was altered. performance of lacs lacs was impaired under both anoxia and submergence con- ditions compared with wild-type plants (fig. ). similar observations were described for plants with constitutive activation of the hypoxia- stress response pathway ( ), although it should be mentioned that the impact of constitutive activation of the erfvii signaling pathway on plant performance under stress conditions also appears to depend on the experimental growth conditions and the recovery treatment ( , ). altogether, our data give rise to a model de- scribing that the control of endogenous acyl-coa levels through lacs activity is a prerequisite to properly induce hypoxia-tolerance responses in plants. lacs activity is reduced by depletion of atp. to explain the mech- anism by which lacs activity in plants is affected by hypoxic fig. . acbp is an important element of the low-oxygen stress response pathway in plants. (a) multiple sequence alignment of class ii acbp ankyrin domain compared with acbp and acbp ankyrin domains in a. thaliana ( ). (b) multiple sequence alignment of erfvii dna-binding domain compared with rap . and rap . in a. thaliana ( ). sequences of homologous proteins were obtained from phytozome v . and aligned with clustal x. (c) eleven-day- old seedlings of wild type and acbp after h of anoxia and -d recovery. (scale bar: . cm.) (d) survival scores for wild type and acbp after -h anoxia and -d recovery. data are mean values ± sd; *p < . , n = ( seedlings per replicate). (e) effect of h of hypoxia treatment ( % o ) on the localization of gfp- tagged acbp in epidermal cells. representative pictures are shown. (scale bar: μm.) schmidt et al. pnas | vol. | no. | e p la n t b io lo g y https://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental conditions, we analyzed lacs activity in dependence of its sub- strate atp. first, we monitored the cellular energy status in wild- type plants grown under hypoxia. already after h, the atp level as well as the atp-to-adp ratio were significantly reduced compared with the air-treated control (fig. a–c). to examine at which atp concentration lacs activity becomes substrate lim- ited, an in vitro lacs activity assay was performed. this experi- ment showed that the activity of lacs was atp dependent at atp concentrations below . mm (fig. d), which is close to the estimated cytosolic atp concentration under aerobic conditions in planta ( – ). since atp concentrations in plant cells de- crease during hypoxia ( ), lacs activity is expected to diminish concomitantly. however, it should be mentioned that variations of the atp concentration between tissues or even within a cell (between organelles) might lead to different local atp-limiting conditions for lacs during hypoxic stress. moreover, the hypoxia-induced low-energy status will also influence other pro- cesses that are not covered by the analyses that we describe here. to verify that a drop in atp can trigger hypoxia responses of plants in air, we chemically inhibited mitochondrial respiration using antimycin-a. indeed, after h of μm antimycin-a treatment of rosettes in air, several hypoxia-responsive genes were significantly induced (fig. e and si appendix, table s ), while atp levels and the atp-to-adp ratio were reduced (fig. f–h). since application of antimycin-a strongly reduced the oxygen consumption rate of the tissue (fig. i), it is unlikely that fig. . application of c : -coa induces rap . relocalization into the nucleus. (a) representative western blot showing in vitro acbp :rap . complex stability after treatment with c : -coa or c : -coa. pluronic f treatment served as control. (b) quantification of acbp -to-rap . -ratio as shown in a. data are mean values ± sd *p < . , n = . (c) percentage of epidermal cells with nuclear localization of rap . -gfp after treatment with different acyl- coas. data are mean values ± sd; *p < . . (d) localization of rap . -gfp in detached leaves incubated with . % c : -coa, c : -coa or c : -coa dissolved in . % pluronic f under normoxic conditions for h. treatment with pluronic f only served as negative control. dapi staining was used to identify nuclei. arrows indicate nuclei with gfp signal. (scale bar: μm.) e | www.pnas.org/cgi/doi/ . /pnas. schmidt et al. https://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental https://www.pnas.org/cgi/doi/ . /pnas. the induction of hypoxia-responsive genes is the consequence of low-oxygen concentrations here. also an antimycin-a–induced ros burst appeared unlikely to be responsible for the gene in- duction, since the induced genes responded similarly when in addition to antimycin-a also mm of the hydrogen peroxide scavenger dimethylthiourea (dmtu) ( , ) was supplied (fig. e). although it cannot be concluded that reduced atp levels are exclusively responsible for triggering hypoxia responses in plants without performing dose–response analyses of individual and combined compounds, the data provide evidence that the cellular energy status is involved in the regulation of hypoxic gene expression. discussion in this study, we demonstrate that acyl-coas provoke distinct transcriptional responses in plants, suggesting that they are involved in different signaling pathways. specifically, binding of c : -coa to acbp triggers dissociation of the acbp:rap . complex upon an hypoxia-induced energy crisis, resulting in mobilization of the transcription factor rap . into the nucleus. consequently, rap . -mediated gene expression is induced. therewith we reveal fig. . changing oleoyl-coa levels induces low-oxygen responsive gene expression. (a) number of significantly differentially expressed genes in leaves after . -h treatment with different acyl-coas as determined by rna-seq (fdr-adjusted p value < . ). (b) number of go classes in which differentially expressed genes are significantly overrepresented under acyl-coa treatments as shown in a. (c) qpcr analysis of differential expression of hypoxia-responsive genes after acyl-coa treatment in air (reference: f only). data are presented as mean values *p < . , n = . (d) c : -coa levels increase upon hypoxia in wild type. data are mean values ± sd; *p < . , n = . (e) c : -coa levels decrease upon hypoxia in wild type. data are mean values ± sd; *p < . , n = . (f) c : -coa levels are increased in lacs lacs double mutants grown in air. data are mean values ± sd; *p < . , n = . (g) c : -coa levels are lowered in lacs lacs double mutants. data are mean values ± sd; *p < . , n = . (h) expression data for hypoxia-responsive genes comparing wild type and lacs - lacs - in air or hypoxia ( h % o ; mean values, *p < . , n = ). schmidt et al. pnas | vol. | no. | e p la n t b io lo g y the trigger of the erfvii-mediated signaling cascade to activate cellular hypoxia-tolerance responses in plants (fig. ). when the oxygen availability to cells diminishes, mitochondria produce less atp due to a reduced activity of oxidative phos- phorylation ( ). indeed, our plants showed a rapid decrease of their energy status upon hypoxia. already within h, the atp- to-adp ratio dropped significantly and remained decreasing throughout the rest of the experiment (fig. c). consequently, the activity of atp-mediated reactions within the cell is expected to reduce too ( ). here, we show that atp concentration- dependent lacs activity reaches its maximum at an atp con- centration of mm (fig. d) which resembles the concentration in a nonstressed plant cell ( – ). this means that any decrease of the cellular energy status is translated into a reduction of lacs activity. the enzyme lacs is among others located in the plastidial outer envelope where it is provided with c : and c : fatty acids from the stroma by thioesterases that are lo- cated in the inner envelope ( , ). using coa and atp as cosubstrates, lacs activates fatty acids and releases them as c : -coa and c : -coa into the cytosol ( ). when the level of atp drops and lacs activity decreases, the export rate of fatty acids will be reduced. as the elongation and rapid desatu- ration reactions in the plastidial stroma from c : to c : commence, the ratio c : compared with c : that is provided to lacs from the stroma is likely to increase through time under these conditions. as a consequence, the ratio of c : -coa to c : -coa that is released by lacs into the cytosol will in- crease and would readily explain why we observe an increased level of c : -coa compared with c : -coa in plants that were exposed to low oxygen (fig. d and e) as well as in lac- s lacs double knockout lines in air (fig. f and g). acyl-coa fatty acid esters bind to acbp proteins. here, we show that specifically the interaction between c : -coa with acbp results in release of rap . from the acbp : rap . complex while c : -coa does not affect the in- teraction between rap . and acbp (fig. ). a shift of the ratio between c : -coa and c : -coa as described above, will therefore lead to the release of rap . from acbp . in- deed, application of c : -coa, but not c : -coa, increased the number of nuclei in which gfp-tagged rap . accumu- lated (fig. c and d). consequently, also up-regulation of hypoxia-responsive marker genes was observed (fig. a–c). similar to this external application of acyl-coas, also an en- dogenous shift of the c : -coa to c : -coa ratio as observed in lacs lacs mutant lines resulted in the up-regulation of hypoxia-responsive genes already during aerobic conditions (fig. h). altogether, these data describe how the ultimate trigger for release of rap . from acbp is constituted by an energy crisis-provoked response of the acyl-coa pool under hypoxia (fig. ). changes of the cellular energy status happen all of the time as most biotic and abiotic stress conditions affect energy metabolism fig. . decreased tolerance of lacs lacs knockout lines to anoxia and submergence. (a) eleven-day-old seedlings of wild type and lacs - lacs - after h of anoxia and -d recovery. (scale bar: . cm.) (b) survival scores for wild type and lacs - lacs - after -h anoxia and -d recovery. data are mean values ± sd; *p < . , n = ( seedlings per replicate). (c) phenotype of wild type and lacs lacs mutant grown in air (control), or after - or -d submergence-induced hypoxic treatment. (scale bar: cm.) photographs were taken d after the submergence treatment. (d) absolute dry weight of wild-type and lacs - lacs - plants grown in air. data represent mean ± sd (three replicate experiments with every plants per genotype). asterisk indicates significant differences after one-way anova (p < . ). (e) absolute fresh weight of wild-type and lacs - lacs - plants grown in air. data represent mean ± sd (three replicate ex- periments with every plants per genotype). asterisk indicates significant differences after one-way anova (p < . ). (f) relative fresh weight of wild-type and lacs - lacs - plants grown in air, or after or d of submergence followed by d of recovery. data represent mean ± sd (three replicate experiments with every plants per genotype). asterisk indicates significant differences after one-way anova (p < . ). (g) percentage of plants that survived the or d of flooding-induced hypoxia, respectively (mean values ± sd, three replicate experiments with every plants per genotype). *p < . according to one- way anova. e | www.pnas.org/cgi/doi/ . /pnas. schmidt et al. https://www.pnas.org/cgi/doi/ . /pnas. in one way or another ( ). it would be most detrimental for plant fitness, when each fluctuation of the atp level immediately led to the activation of hypoxic gene expression ( ). therefore, the lifetime of erfvii proteins depends on the actual cellular oxygen concentration via the cys branch of the n-end rule for proteaso- mal protein degradation ( , , ). only when an energy crisis is provoked by low-oxygen conditions, the stabilization of rap . enables the protein to accumulate in the nucleus in a sufficient amount to activate hypoxic gene expression. however, when rap . is released from acbp due to an energy deficit that is not related to low-oxygen stress, the protein will be rapidly degraded due to proteasomal activity. therefore, we propose that the acbp :rap . complex forms the initial hub capable of integrating signal inputs related to the cellular energy charge with oxygen concentration-dependent determination of the lifetime of rap . protein (fig. ). subsequently, rap . protein that is newly synthesized after the onset of hypoxia does still undergo n- end rule-assisted stabilization but may not be linked directly to the energy status of the cell. constitutive activation of the molecular stress response to low oxygen in the lacs lacs mutant background led to reduced tol- erance to low oxygen as well as to flooding stress (fig. ). this fig. . decreasing the cellular atp level constitutes limiting conditions for lacs activity and induces the expression of low-oxygen responsive genes. (a) atp levels under hypoxia (mean ± sd, *p < . , n = ). (b) concentration of adp in wild-type seedlings grown under long-day conditions and exposed to hypoxia. data shown are given in nanomoles per gram fresh weight and represent the mean ± sd of independent replicates (n = ). (c) atp-to-adp-ratio under hypoxia (mean ± sd, *p < . , n = ). (d) in vitro lacs activity depends on atp concentration (mean ± sd, *p < . , n = ). the gray area marks the atp- concentration range usually determined in plant cells. (e) differential expression of hypoxia-responsive genes after h of mm dmtu and/or μm antimycin-a (aa) treatment under aerobic conditions (reference: mock-treated control). data are presented as mean ± sd, *p < . , n = . (f) atp levels after h of μm aa treatment (mean ± sd, *p < . , n = ). (g) concentration of adp in wild-type seedlings exposed to h of μm aa treatment. data represent mean ± sd (n = ). asterisk indicates significant differences after one-way anova (p < . ). (h) atp-to-adp-ratio after h of μm aa treatment (mean ± sd, *p < . , n = ). (i) oxygen consumption rate in wild-type leaves upon h of μm aa treatment. data represent mean ± sd (n = ). asterisk indicates significant difference after student’s t test (p < . ). schmidt et al. pnas | vol. | no. | e p la n t b io lo g y observation is congruent with earlier observations that consti- tutive activation of the hypoxia-stress response in plants via overexpression of a stable version of rap . protein reduced tolerance to hypoxia ( ), although other studies indicate that the latter phenotype is likely conditional to growth conditions and recovery treatment too ( , ). this underlines the impor- tance of a timely control of stress responses that are optimally adjusted to the actual environmental conditions. the integration of (i) energy-dependent changes in c : -coa levels as cellular trigger signal with (ii) the homeostatic control of the lifetime of rap . in an oxygen concentration-dependent manner pro- vides a highly specific control mechanism to initiate hypoxic re- sponses. the mechanism guarantees that a full low-oxygen response is activated only when hypoxia is detrimental for the plant’s energy status. the atp dependence of oleoyl-coa synthesis by lacs in combination with the impact of oleoyl-coa on the interaction between rap . and acbp exposes mitochondrial activity as an early trigger for hypoxia signaling. consistently, manipulating mitochondrial atp synthesis using inhibitors of specific re- spiratory complexes like antimycin-a induced rap . -controlled hypoxic gene expression even under aerobic conditions ( ) (fig. e). it is striking that the induction of hypoxic gene expression in air by acyl-coas (fig. c and h) or antimycin-a (fig. e) was lower compared with the induction of these genes by hypoxic conditions (fig. h). this observation stresses the impact of ad- ditional oxygen-dependent regulatory mechanisms, such as the n- end rule-mediated reduction of rap . lifetime in air. in this context, it is worth mentioning that the control of low-oxygen stress responses is not only linked to the oxygen and energy sta- tus of the cell, but it is also known to be influenced by other cellular factors such as nitric oxide ( , ), hydrogen peroxide ( ), calcium ( , ), and potassium ( ). in the near future, it will be intriguing to expand the mechanistic explanation of how the energy and oxygen status of a cell is integrated upon low- oxygen stress with these additional signaling components ( ). acbps are found in all kingdoms of life, while erfviis are highly conserved among higher plants. moreover, the interaction domains of both protein families are highly conserved in plants (fig. ). therefore, the acbp:erfvii signaling hub as pre- sented here may represent a universal mechanism in plants to initiate hypoxia-induced stress responses via the integration of multiple cellular signals. moreover, the specific interaction of acbps with various acyl-coas on the one hand (fig. ) and the distinct cellular responses provoked by individual acyl-coas on the other hand (fig. a and b) suggest that many additional possibilities may exist of how acyl-coas can modulate cellular signaling pathways in plants. materials and methods plant materials. arabidopsis thaliana ecotype col- was used as wild type for all analyses. the s:rap . -gfp line and lacs - lacs - and lacs - lacs - double knockout lines were described previously ( , ). the acbp knockout line (sail_ _c ) was obtained from the nottingham arabidopsis stock center (si appendix, fig. s ). growth conditions and analysis of oxygen deprivation response. for testing anoxia tolerance of seedlings, seeds were sown on half-strength ms medium containing . % (wt/vol) sucrose, stratified for h at °c, and germinated at °c day/ °c night with a photoperiod of h light ( μmol·m− ·s− ) and h dark. at day , seedlings were exposed to full anoxia, by placing the culture plates in an environment containing % nitrogen, for h in the dark to avoid photosynthetic oxygen production. after d of recovery, the survival score was determined as previously described ( ). for submergence assays, seeds were sown in moist soil, stratified at °c in the dark for h, and germinated at °c day/ °c night with a photoperiod of h light and h darkness. the -wk-old plants were submerged in water in -cm high plastic containers and kept in the dark to avoid photosynthetic oxygen production. leaves stayed cm under the water surface. after or d, water was re- moved from the boxes and plants were placed back under photoperiodic conditions ( h/ h, light/dark). submergence tolerance was assayed after d of recovery. for acyl-coa pool measurements, plants were grown on horizontal agar plates containing . % agar in / ms medium (ph . ) with mm sucrose for wk under long-day conditions ( h in μmol photons·m− ·s− at °c and h in μmol photons·m− ·s− at °c). after . h in light, they were subjected to hypoxia in the dark by exposition to a stream of air containing % (vol/vol) oxygen, supplemented with nitrogen and ppm carbon di- oxide. plants were harvested by freezing in liquid nitrogen after h, h, and h of hypoxia. for normoxic control, untreated plants were harvested si- multaneously with the start of hypoxic treatment. for expression analysis after acyl-coa treatment, wild-type seeds were sown in -well plates containing half-strength liquid ms medium, stratified for h at °c, and germinated at °c day/ °c night with a photoperiod of h light ( μmol·m− ·s− ) and h dark. at day , seedlings were treated with different acyl-coas at a final concentration of . % in . % pluronic f . pluronic is a nonfatty acid-based detergent which means that the detergent properties of pluronic in solubilizing fatty acyls are not con- founded by fatty acyls derived from the detergent itself ( ). cloning of constructs. coding sequences (cdss) were amplified from a cdna template using phusion high fidelity dna polymerase (thermo fisher sci- entific). the acbp cds was cloned into pentr-d and recombined into pk fwg ( ) to fuse it with gfp. for in vitro expression, the cds of acbp was fused n terminally with a flag tag by pcr and cloned into pf a wg bydv (promega), while the cds of rap . was fused c terminally to fig. . triggering low-oxygen responses in plants integrates the cellular energy and oxygen status via modulation of oleoyl-coa levels. oxygen limitation reduces cellular atp levels, which results in increased c : -coa levels. dissociation of erfvii protein (as shown here for rap . ) bound to acbp at the plasma membrane is promoted by c : -coa. free erfvii protein is stable under low-oxygen conditions and relocalizes into the nucleus to activate hypoxic responses. e | www.pnas.org/cgi/doi/ . /pnas. schmidt et al. https://www.pnas.org/lookup/suppl/doi: . /pnas. /-/dcsupplemental https://www.pnas.org/cgi/doi/ . /pnas. cfp by pcr and cloned into pf a wg bydv (promega). a complete list of all primers used is provided in si appendix, table s . plant transformation. transgenic acbp -gfp plants were generated by trans- forming wild-type plants with the vector pk fwg ( ) containing the acbp cds fused in frame to gfp at its c terminus. t seeds were screened for kanamycin resistance and the presence of gfp signals by confocal microscopy. qrt-pcr. rna extraction, digestion of genomic dna, cdna synthesis, and qrt-pcr analysis were performed as described previously ( ). for all experi- ments, four to five independent biological replicates were used, as indicated in the figure and table legends. for normalization, ubiquitin expression was used according to ref. . primers for hypoxia core genes, lacs genes, and ubi are given in si appendix, table s . rna-seq analysis. illumina hiseq sequencing was performed according to standardized protocols as described in detail in si appendix. transcriptome analysis was performed by means of clc genomics workbench v. using the a. thaliana reference sequence (tair ). expression values were normalized using quantile normalization and pairwise statistical analyses comparing the treatments performed using false discovery rate (fdr)-corrected p values based on baggerly’s test ( ). confocal imaging. for protein localization studies, gfp signals were imaged and analyzed with a leica dm tcs sp confocal microscope (leica microsystems). nuclear staining was performed by using dapi (molecular probes) according to the manufacturer’s instructions. for quantification of nuclear translocation of rap . after acyl-coa treatment, dapi-stained nuclei per plant (five plants in total) were analyzed per treatment. leaves of -wk-old soil-grown s:rap . -gfp plants were incubated for h with different acyl-coas at a final concentration of . % in . % pluronic f in a -well plate under continuous shaking in the light. the experiments were repeated three times. in vitro binding assay. the method to determine whether acyl-coas affect the interaction between acbp and rap . is explained in detail in si appendix, supplementary information text and fig. s . in brief, both proteins were synthesized using wheat germ extract ( ). the full cds of rap . was fused c terminally with the cds of cfp, and the cds of acbp was n- terminally fused with a flag tag. rap . -cfp protein was bound to gfp– trap-a beads (chromotek) and incubated with acbp protein overnight. subsequently, beads were resuspended in wash buffer containing different acyl-coas at a final concentration of . % in . % pluronic f , or as a mock control of only . % f . after one night of incubation, the buffer was replaced and the composition of the protein complex retained to the beads was analyzed on a western blot. analysis of acyl-coa esters. acyl-coas were extracted, derivatized, and an- alyzed using hplc as described earlier ( ). detailed information about the method is provided in si appendix. lacs in vitro enzyme assay. the in vitro lacs enzyme assay was carried out as described previously ( ) using protein that was heterologously expressed in escherichia coli ( ). details of the method are explained in si appendix. atp and adp quantification. atp and adp were extracted with % tri- chloroacetic acid ( ) and analyzed after derivatization by hplc as described previously ( ). details of the procedure are described in si appendix. analysis of oxygen consumption rates. for the determination of oxygen consumption rates, -wk-old plants grown on soil under short-day conditions ( h in μmol photons m− ·s− at °c and h in μmol photons m− ·s− at °c) were used. starting h before measurement, the plants were sprayed every hour either with mm mes buffer (ph . ) containing μm antimycin-a ( ) or with mm mes buffer for control. this treatment was done in the last hour of dark phase and h into the light phase, and then measurement of oxygen consumption rates at normoxic conditions was performed as described before ( ) using the respective spraying solution. in a similar setup, the effect of different acyl-coas on the oxygen consumption rate was tested by incubating leaf disks in acyl-coas at a final concentration of . % in . % pluronic f . statistical analysis. statistical evaluation of significant variation between treatments or genotypes was done by performing student’s t test or one-way anova where appropriate. data availability. the rna-seq gene expression data are available in ncbi’s gene expression omnibus (geo) through geo series accession no. gse . acknowledgments. we thank sandro parlanti and frauke augstein for valuable support. this work was supported by grants (to j.t.v.d.) 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( ) the membrane-bound nac transcription factor anac functions in mitochondrial retrograde regulation of the oxidative stress response in arabidopsis. plant cell : – . e | www.pnas.org/cgi/doi/ . /pnas. schmidt et al. https://www.pnas.org/cgi/doi/ . /pnas. international journal of sustainable energy planning and management vol. corresponding author - e-mail: .ahmad@dr.sharda.ac.in international journal of sustainable energy planning and management vol. – abstract the relevance of energy in the growth and development process necessitates giving serious attention to the planning, production and consumption of energy. energy modelling carried out in recent years using sophisticated and computerized models has become an important tool in planning and analysis of energy systems. these models rely heavily on future assumptions regarding the expected economic conditions in consideration to the current and unfolding situations of the economies in question. however, due to uncertainty of the future economic conditions, informality of especially developing economies and too much reliance on technical expertise of development/collaboration partners, these assumptions are mostly not well formed, hence found untenable to adequately capture the evolving events. this is more evident if one looks at the alternative energy projections made by different organizations using different understandings and assumptions. this study compares the best energy demand and supply projections of necal as the best and most recent energy model in nigeria with other alternatives projections and previous energy commission of nigeria - ecn’s model to showcase the discrepancies and their economic consequences. it is found that in most cases of energy planning collaboration, modeling assumptions do not well capture the current and future economic realities of the assisted nations, resulting in misleading projections. policy implications and recommendations are discussed at the end. . introduction/background the transition to sustainable energy system at city, state, region, country and the world at large is crucial to achieving the goals of the global development agenda and paris climate agreement [ , , , & ]. effective transition to renewable energy system will directly depend on the comprehensiveness of energy planning [ , & ] including the analysis and projec- tions of energy demand and supply as well as the targeted level of economic activities being envisaged for a given nations [ ]. several methods and approaches to energy planning have been evolving over the years and computer-based energy modelling [ ] has become the order of the day in modern energy planning [ , , , & ]. energy modelling relies heavily on huge amount of economic data and some economic assumptions regarding the future expected conditions of the economy whose energy demand and supply is being modelled. on the other hand, the economic data are mostly unreliable in developing countries, the future assumptions are not always perfect in the continuously dynamic world with a lot of unforeseen changes [ & ]. estimations with accuracy that stand the test of time are very difficult to arrive at leading to poor energy energy modelling as a tool for curbing energy crisis and enhancing transition to sustainable energy system in nigeria ahmad garba khaleel ,a, prof. milindo chakrabartib,c a department of economics & international business, school of business studies, sharda university, plot , knowledge park iii, greater noida, uttar pradesh, india. b jindal school of government and public policy, o.p. jindal global university, sonipat, haryana- , ncr of delhi, india. c research and information system for developing countries, ihc, institutional area, new-delhi, india. keywords: energy modelling; necal ; maed; message; projections; electricity url: http://dx.doi.org/ . /ijsepm. . . mailto: .ahmad@dr.sharda.ac.in http://dx.doi.org/ . /ijsepm. . . international journal of sustainable energy planning and management vol. energy modelling as a tool for curbing energy crisis and enhancing transition to sustainable energy system in nigeria projections of necal , carries out a small comparative analysis of the electricity demand and supply from the model and other alternative projections estimated using similar or different assumptions for nigeria. policy implications and recommendations are discussed at the end, before which an overview of energy planning (modelling), nigeria’s modelling experience and brief review of necal ’s features and weaknesses is given. . understanding energy modelling before dwelling on energy modelling, it will be good to take a look at the concept of modelling generally, its nature and associated terminologies. modelling is a method of studying or solving problems through a simplified systemic representation that enables system analysis and prediction from the observed and recorded behavior in a simulation of the original system. it involves evaluating and understanding the interaction of the components of a real or theoretical system by designing its representation (model) and executing it in real time. a model in this case is defined by singh and singh [ ] as a simplified representation of a real or theoretical system at some particular point in time or space intended to provide understanding of the system. energy model is then a simplified representation of a real or theoretical energy system designed and run at a particular point in time or space with the aim of getting as much information and understanding as possible regarding the present or future energy variables of the replicated system [ ]. energy modelling is the method of evaluating and understanding the interaction between the different components of a real or theoretical energy system through designing its simplified representation and executing it. modelling is important in that it enables one to choose and invest wisely by testing every aspect of the proposed changes or additions without committing resources [ & ]. it allows for compression and expansion of time, provides team training as it gives clear understand- ing of system behaviors or an aspect of it by allowing problem diagnoses, enables exploration of possibilities, identification of constraints, allows visualization of plans and systems as well as its requirement specifica- tion. on the other hand, it should be understood that, modelling is difficult and requires special and continu- ous training as the real life systems being modelled are constantly dynamic especially in the area of energy and related dynamic economic variables that serve as inputs planning that results in energy (electricity) crisis in most of the developing world particularly africa [ , & ]. this fault is not limited to african developing countries as noted in a report by oxfam international on the eve of nd conference of the parties to the kyoto protocol at morocco in . the report claimed that “a year after the paris climate deal, most vulnerable are still not getting financial support they need” and also the “amount of net financial assistance going to help developing countries fight climate change has been miscounted by tens of billions of dollars” [ ]. these errors, as recently studied and confirmed by [ ], whether by developing countries or their advanced development partners have a dimension in creating serious economic imbalances. one such imbalance this paper intends to study is in the area of the persistence of energy crisis in nigeria despite the presence of modern energy modelling tools and their continuous upgradation. the failures of these models to adequately capture the local and changing conditions of the economies [ ] they are intended for has been understood to be the root of the problems [ , , , ]. nigeria is not only the largest economy in africa, it is also the most populous and having amongst the largest growth in populations and energy demand. in the estimates of the economist in , nigeria will have the third largest population in the world by the year after india and china [ ]. the combined effects of rapid population growth and urbanization in the developing world, particularly africa [ ], on the growth of energy demand are unimaginably undermining climate action. this is even more important in africa with high energy intensity in gdp [ , ] and low access to clean energy, that the share of people without access to is growing [ ]. this is true because, the current energy crisis in africa – being either the result of poor energy planning or wrong estimates and assumptions – is a testimony to the fact that, unless something is done, the same result will be recorded for climate action in the continent, despite their long standing advanced development partners. one possible area of intervention is in improving energy planning by improving the relationship between energy projections and actual energy production and consumption as well as their effects on the economies [ ]. this paper intends to use the case of nigeria energy calculator – necal to showcase the evidence of these gaps by comparing its best projections with other projections from the local and some renowned international energy organizations for the same economy (nigeria). the paper, after highlighting the best energy international journal of sustainable energy planning and management vol. ahmad garba khaleel, & prof. milindo chakrabarti simulation evaluation model for india as the two national specific models developed based on the besom model [ ]. other country level models developed in france are modele d’evolution de la demande d’energe (medee)/model for energy analysis and energy flow optimization model (efom). the econometric approach of linking growth to inter-industry models with endogenously determined inter-industry input-output coefficients was pioneered by [ ] in the united states. in wien automatic system planning (wasp) was developed by international atomic energy agency as a response to calls for and attention given to integrated planning and coordinated modelling efforts, which was extensively used and mod- ified over the years. in the s focus shifted to ener- gy-environment linkages to cater for environmental concerns, while in the s other climate change related issues were further added to the modelling efforts. this new change required very long-term ( years or more) understanding, making efforts looking beyond (normal - ) to years to cause the validity of assump- tions to be complex due to high risks and uncertainty. the incorporation of the probabilistic risk analysis made the development of very long-term energy environment model initiative of the european union possible. along with these are models like asian-pacific model (aim), second generation model (sgm), regional air pollution information and simulation (rains)-asia model, global , dynamic integrated model of climate and the economy, poles etc. existing models like markal are also expanded, while long-range energy alternative planning – leap system became national communica- tions standard for unfccc reporting. these developments also witnessed the divergence of views between bottom-up (focusing on energy sector’s technical characteristics) and top-bottom (stressed on the price and markets) model builders that failed to be settled. [ , ] further reviewed the categorization of energy models in the works of [ ] based on modelling approach, [ ] based on paradigm, space, sector and time, while [ ] uses modelling approach and meta-net approach. within all the categorizations, models are found based on linear programming-based method, input-output approach, econometric method, process models, system dynamics and game theory, (top-down and bottom-up) methodology, partial equilibrium, general equilibrium or hybrid, modelling technology (optimization, econometric or accounting) and the spatial dimension (national, regional and global), sectoral coverage, time horizon and spatial focus. into the models. it is difficult for energy planners in developing countries with little to no training/experience to keep up with the changing situations. and so, the gen- erated results mostly appear random, not in agreement with the current changing realities. as such, sometimes the process becomes time consuming, as is modelling generally, but even more without the right inputs and outputs. it is therefore expensive and the results are used inappropriately in generating energy policies that will not serve their own purposes. . . historical evolution of energy modelling bhattacharyya and timilsina [ ] observed that, the world dynamics of jay forrester and its application in meadows et al. ( )’s limit to growth, despite their infamous and limited representation, was traced as the pioneering efforts towards global large-scale energy modelling as well as most of the national modelling initiatives. other key factors in this list are the collective effort of the us eia and international institute for applied system analysis in the workshop on alternative energy sources and the high prices of oil in the s. one of the earliest approaches to energy analysis and modelling is the energy accounting framework that is used in generating energy balance as the most simplified energy system representations [ ]. its comprehensive and consistent nature has been enjoyed as early as the s in the usa [ ] and is still popular in st century modelling practices and models [ , ]. reference energy system framework, by hoffman, is an expansion of the accounting/energy balance approach that focuses on the actions involved in the entire supply chain. this is done by taking the technological characteristics as well as all possibilities of future technological improvements of the system into account thereby facilitating analysis of different energy scenarios, hence setting a new line of energy system modelling tradition. with the complexities brought by pictorial presen- tations and the associated optimization techniques benefits, linear programming has been an integral part of reference energy system leading to several models being developed for many purposes and with different capabilities over the years including most electricity related models and the brookhaven energy system optimization (besom). other methods that followed it include the more generic and dynamic or multi-period market allocation (markal) model as the best of its days, the mexico’s energeticos and the energy research institute – teri energy economy environment international journal of sustainable energy planning and management vol. energy modelling as a tool for curbing energy crisis and enhancing transition to sustainable energy system in nigeria nigeria stands to benefit from these tools, as energy supply mechanism for any country has to look for the ways to provide for all categories of energy demand in the economy. the process of doing begins with energy modelling, but as iterated by numerous modelling and development studies, the needed skills & expertise are lacking or inadequate in the developing countries, hence the need for technical assistance. the business of international technical assistance is at the center of most interactions between developed and the developing countries and also mostly shapes the nature and conditions of bilateral, multilateral and international private, public as well as private public partnership-ppp collaborations. under normal conditions, the nature of these collaborations needs to take into account the mutual interests of both collaborators or partners to produce a win-win situation that promotes both partners, an ideal hardly met [ , , , ]. this is because, solutions built while depending on the assistance of developed nations are mostly based partly on the realities and experiences of the developed nation helping to set it up. the usual issues faced are: down the road there will be mismatch between the solutions offered by the model and the realities on ground and the trained staff may not be able to effectively use it or address problems it may develop. at the end its overall purpose may be defeated in the sense that it may further complicate issues for the developing nation and the locally trained staff on what way to go about it. the model, despite its high level of capabilities compared to the previous models may just be there without achieving its target as is mostly the case. one typical example of such a recent collaboration is in the development of the newest and the best among the nigeria’s suite of energy modelling tools. the nigeria however with this long history, developments and all these differences, it will be interesting to know where nigeria stands as far as energy modelling is concerned. this is covered in the next section. . energy planning (modelling) in nigeria energy modelling in nigeria is part of the mandate of the ecn as the government’s strategic planner and coordinator of national policies in the field of energy and all its ramifications [ ]. in fulfilling this mandate, the commission has over the years been utilizing many computer based tools of energy modelling, planning and analysis including; • model for analysis of energy demand – maed, • energy and power evaluation program – enpep, • wien automatic system planning – wasp for electricity, • model for energy supply strategy alternative and the general environmental impacts – messege for strategizing energy supplies, • simplified approach for estimating environ- mental impacts of electricity – simpacts for projects and plants financial viability assessment • energy forecasting framework and emission consensus tools – effect the recent development of necal is another milestone in this journey and addition to the suite of tools of energy analysis at its disposal as according to [ ], it is still keenly utilizing message and maed. thus necal is currently the best and most advanced energy modelling tools at the disposal of ecn because it has all the features of the two and even more as captured in table as adopted from ecn’s necal documentation. table : comparing necal , message and maed, source: [ ] s/no. maed message necal . excel-based energy demand modelling framework or modelling tool. energy supply modelling framework based on dynamic linear programming. integrated energy demand and supply mode; excel and web-based. . simulation modelling framework. optimization model. both demand supply are simulation models . maed does not calculate emissions. calculates up to maximum five user defined emission types on the supply side based on input demand. calculates the emissions on the demand side for fuels (e.g. gas, petrol, fuelwood, etc.); calculates emissions from electricity at the supply side on the supply. . takes a very long time to run a single scenario. takes a very long time to run a single scenario. can run several scenarios within a very short time. international journal of sustainable energy planning and management vol. ahmad garba khaleel, & prof. milindo chakrabarti transition to a low carbon economy, as well as the choices available for clean modern energy access for all. the calculator is helpful in exploring a range of available pathways. however, it misses to point out the optimal one, which would instead be needed to allow policy makers to take the right decision promptly. this is of vital importance for an economy in a serious energy crisis that coincided with lack or inadequacy of energy modelling expertise, hence having an optimal option will reduce delays that would be caused by debates as to which of the available pathways to follow. iv. the model has been developed by focusing exclusively on nigeria and its options for ghg emissions reduction and energy security. v. the analysis under the model looks at what might be possible to deliver in the coming years up to , but does not propose or identify the required policy decisions to ensure this future. in other words, the nigeria energy calculator does not provide a detailed policy framework and the trajectories should not be considered as projections based on policy decisions. vi. the necals platform does not ‘recommend’ or ‘prefer’ any one scenario or pathways over the others. it merely provides the user a way to understand the realm of possible scenarios and their implications and post their preferences and choices as a contribution to the debate on sustainable energy development for nigeria. necal is the best energy modelling tool nigeria has gotten till date, it is by far the most up-to-date equipped with energy and emission analysis tools. however, the weaknesses do not stop at those clearly stated in the model documentation as other key issues are neglected in its global economic assumptions on nigeria. key amongst which are: i. a major issue of consideration that was missed by necal developers is the future role of agriculture not only in nigeria but in the whole region as contained in the agenda of the african union. the place of agriculture in the necal was not explicit despite the fact that agriculture provides almost % of nigeria’s gdp and over % of employment as at , energy calculator (necal ) model is typical of the story line above in the sense that it did quite try to capture the urban sector of the economy, but as far as the nigeria’s rural sector is concerned, the model has not done its job well. one may not be right to this claim, given that, the developers of necal were so honest and open to some of its fundamental weaknesses, all of which are discussed in the next section. . overview of necal necal is an integrated model of energy, emissions and land use in nigeria and aims to identify energy secure pathways for supply and demand of energy between now and [ ]. it was developed by the nigeria energy commission with the assistance of united kingdom department of energy and climate change (based on the uk calculator) through the british high commission, abuja and launched in the year with the following three key objectives; i. to offer a platform to facilitate academic and policy debate about the possible future pathways for the nigeria’s energy sector and enable prioritizing some policy interventions for deeper analysis. ii. to help users (individuals, businesses and govern- ment) understand the wide range of possible energy pathways available to the country from highly pessimistic to highly optimistic scenarios. iii. to provide indicative numbers for demand and supply, for each scenario in the range of possibilities, and potential implications on issues such as import dependence, cost and land requirement. as stated earlier, it would do justice to the developers of necal to hail their honesty and openness in terms of some of its weaknesses they mentioned, which are summarized as follows: i. the model does not capture potential positive and negative feedback impacts on the economy from the levels of effort implied by the pathways. ii. it focuses on identifying the least-cost pathway to meet nigeria’s energy demand in a reduced emission manner up to year , but in some cases questionable assumptions are used (e.g., unrealistically low cost of coal at some stage of the considered timeframe). iii. the necal demonstrates the scales that are likely to be required for nigeria to make international journal of sustainable energy planning and management vol. energy modelling as a tool for curbing energy crisis and enhancing transition to sustainable energy system in nigeria . best necal energy scenario/projection it is interesting to know that there are four levels of tra- jectories built-in on the model namely; least, determined, aggressive and heroic efforts scenarios that users can select from in using the model. these trajectories have different levels of potential implementation in energy technology improvement, behavioral, structural, lifestyle as well as fuel choices that affect the overall volume of energy demand and supply in the economy. among these levels of efforts, level four ( ), which is termed as the ‘heroic effort’ scenario attempts the most highly laud- able, elaborate and ambitious alteration of the energy system towards the highest physical and technical limits possible within the prevailing economic conditions. the results from this scenario are graphically portrayed in figure showing the level of energy demand and supply possible as far as the models’ understanding and assump- tions about the economy of nigeria including gdp, pop- ulation and their growth rates, speed of urbanization etc. the graphical results of necal (web version) best (heroic effort) scenario show selection of best possible options in all variables and assumptions as well as the final energy demand, primary energy supply and green- house gas emissions. tables and give similar best scenario results from the excel version of necal that clearly and categorically shows the volume of the energy demand and supply on the five year intervals from to . the tables also show the volume of energy demand and supply from various renewable and non-renewable energy sources and the totals of each of the five ( ) year intervals. the percentages of the same are also given in the lower segment of each of the tables to show the relative significance of each source or vector of energy. nigeria’s energy projections from the best (heroic effort) scenario are presented in table where it is clear that there is a steady overall increase in energy demand from twh in to twh in (equivalent to . % increase in total energy demand). it is interesting to see that this energy demand increase trend is not shared by all vectors in nigeria as transport, cooling, lighting and appliances recorded increase while decline is registered by industry and cooling vectors. the highest increase is recorded by lighting and appliances vector from twh to twh equivalent to almost . % change in the share of the country’s energy demand. while the least increase is by transport the year the model was launched. the sector is being transformed by commercialization at the small, medium and large-scale enterprise levels that is evident by a significant simultaneous expansion and mechanization. the key role of agricultural energy demand in the largest african economy’s energy model cannot be overemphasized and the omission of which would be an unforgivable miscalculation. ii. undermining the nigeria’s capacity in the use renewable energies by including and capitalizing on a scenario where the current trend of refine petroleum products importation is extended to include electricity from sources out of the country. this is despite the estimations of the renewable potentials of before and recently after the model like [ ]. iii. the recent developments in the international market for renewables was neither anticipated nor provided for while developing the necal , which would give us better scenarios than those projected in the model. iv. cooling energy demand especially in the household sector is overemphasized as the number of household that actually have cooling system and as such need energy for cooling is not that significant from the perspective of the overall population with majority below poverty line. these are important issues to the economy particu- larly with regards to sources and extent of energy demand and the renewable energy capability as well as potentials. wrong energy projections may result from such omissions further leading to underestimating the capabilities of existing infrastructure and some possibil- ities of technological improvements. the effect may also undermine the role of the available energy reserves and potentials of resources, existing and changing energy policy and regulatory environment and energy investment. this is also true for their combined effects on the production and consumption of energy and its market conditions as well as ultimately growth and development of the economy. it is observable in most future energy projections in both developed and devel- oping countries, that while highlighting the current challenges and the unwanted results of inaction or right kind of action, they are explicit as to the highest positive outcomes that may follow the best course of action [ , , , , & ]. international journal of sustainable energy planning and management vol. ahmad garba khaleel, & prof. milindo chakrabarti from the energy supply side as shown in table , up till the bioenergy will be the dominant source of energy in nigeria with over % and over % shares of nigeria’s energy supply in and respectively. the relevance of oil, over % in will be reduced to a little over % in , while coal currently relying on imports will become the second dominant source of energy in nigeria to the tune of over % in , the year at which the world is ironically targeting carbon neutrality. gas share will be increased from . % to % between and while nuclear fission will start from twh to twh corresponding to . % change in the share of energy demand. it is ironic – though it may comply with the then nigeria’s economic conditions – that, the industrial demand for energy showed the highest and steady decline from twh to twh (a . % decrease in the share of the total nigeria’s energy demand) over the period of the projections. this is contrary to the recent developments in the country in terms of industrialization and agricultural transformation that stand to be a major source of energy demand. final energy demand primary energy supply greenhouse gas emissions % percentage change compared to pj/yr domestic transport behaviour shift to low carbon emission transport technology fuel switch for internal combustion engine domestic freight cooling demand efficiency of cooling system residential lighting, appliances & cooking technology pathway (cooking) growth in industry with gdp energyintensity of industry service sector demand tor cooling efficiency of cooling system service sector lighting, appliances & cooking technology pathway (cooking) total cooking lighting & appliances industry pj/yr mtco e/yr - oil total coal bioenergy total fuel combustion bioenergy credit natural gas power stations biomass power coal power stations nuclear power stations wind hydroelectric power stations small hydroelectric power stations grid connected solar pv concentrated solar power stand alone solar photo voltaic electricity imports land dedicated to bioenergy livestock and their management volume of waste and recycling bioenergy imports type of fuels from biomass lndigerous fossil-fuel: coal lndigerous fossil-fuel: oil lndigerous fossil-fuel production: gas question marks take you to one page descriptions of each choice. the least effort possible on this choice. viewed as ambitious, but reasonable by most experts. viewed as unlikely without significant change from the current system and/or significant technological breakthroughs. the upper end of what is thought to be physically plausible by the most optimistic observer. notes figure : best necal energy scenario/projection using web version necal model table : best necal energy demand scenario final energy demand twh vector transport industry cooling lighting & appliances cooking total final energy demand% twh% vector transport . . . . . . . . . industry . . . . . . . . . cooling . . . . . . . . . lighting & appliances . . . . . . . . . cooking . . . . . . . . . international journal of sustainable energy planning and management vol. energy modelling as a tool for curbing energy crisis and enhancing transition to sustainable energy system in nigeria of the model. demand for electricity in lighting and appliances ( . % of total energy demand) have the highest and dominant share of the country’s energy demand. hence the focus of our analysis here will be narrowed down to electricity demand and supply projections, where a comparison will be made between necal and other three alternative projections to see the level of agreement or otherwise. this analysis is carried out in the next section. . alternative electricity projections for nigeria the closeness of the necal projections to the realities in nigeria can be gauged by looking at other projections that focus on the same issues and used similar or different assumptions. this analysis will be useful in such a way that, where there is an agreement of focus or assumptions the two projections will be compared to see first, which is the best reflection of changing conditions in nigeria and second, which is better for nigeria’s future energy system. the scope of the analysis here is narrowed down to electricity as one of the energy vectors that regarded to have the least development in nigeria leading it to rely on imports to the tune of % of the total energy supply. three from at twh to reach twh by repre- senting . % and over % respectively. hydro, solar and wind combine currently supplying less than % of nigeria’s energy are expected to supply %, almost % and . % respectively by . the shortage of power supply in nigeria according to the projections is expected to continue and even increase to heavily rely on electric- ity imports from other countries to the tune of over twh by corresponding to over % of the total energy demand in the country. the overall energy supply will grow from twh in to twh in , almost % increase over the period of the projections. key observation from tables and generally is the excess of energy supply over demand and simultaneously excess electricity demand over local supply due to low envisaged generation even in the most heroic effort of the necal ’s scenarios leaving no option but the importation of electricity into nigeria. this is despite the fact that there exists a huge excess of energy supply twh over demand twh in coupled with massive renewable energy potentials and growing fossil energy reserves that are slowly being developed. one may not be wrong to argue that, from the projections of necal , electricity is one of the most important energy issues in nigeria and as reflected in the estimations table : best necal energy supply scenario primary energy supply twh vector nuclear fission solar wind hydro electricity oversupply (imports) – – – – – – – – – bioenergy coal – – oil gas total primary energy supply% twh% vector nuclear fission . . . . . . . . . solar . . . . . . . . . wind . . . . . . . . . hydro . . . . . . . . . electricity oversupply (imports) . . . – . – . – . – . – . – . bioenergy . . . . . . . . . coal – . – . . . . . . . . oil . . . . . . . . . gas . . . . . . . . . total international journal of sustainable energy planning and management vol. ahmad garba khaleel, & prof. milindo chakrabarti different from those in necal , however, the basic observations is that there is a symmetry of pattern in the growth of demand over the period that the two estimations cover equally. that is from to , the growth of cooling, lighting and appliances energy demand, which is usually provided using electricity, in necal is about % and power demand growth is a little above % for [ ]. the difference can be attributed to time, methods and economic assumptions of estimations, but overall they both indicated an ever growing demand for energy and the need for increased generation. however, while [ ] projections were silent about the way and manner the excess demand over supply of electricity can be met, necal predicted the import of electricity into nigeria. . . comparison of electricity supply projections from the supply side, this study considered the work of pwc on the future of electricity in nigeria. the pwc’s projection targets increasing the generation capacity to projections were analyzed in comparison to the necal best electricity demand and supply projections, one from demand side, the second from supply side and another from demand and supply sides. . . comparison of electricity demand projections with the aim of determining the nature of electricity load demand for the purpose of planning future expansions of current network and also determine load distribution on the existing generating plants, [ ] analyzed past load demand and estimated the future load till . this was done using the forecasting method of stochastic/ probabilistic extrapolation based on time series analysis of past load demand curve and straight line graph/curve to make decisions for improving the power system balance to ensure more quality and reliability of power supply and its network. the nigeria’s demand load data for the years between and was used as the basis for the estimations to project load demand up-to . the figures as shown in table appear quite table : electricity demand projections based on real load demand data, source: [ ] year predicted load demand (mw) , , , , , , . gw . gw % % % % gw gw gw gw capacity utilisation (% of installed capacity) transmission loss (% of generated) % % distribution loss (% of generated) gw gw kwh kwh scenario ( ) base case ( ) installed capacity generated transmitted distributed per capita annual power consumption leap | accelerating growth in power generation capacity and improving utilisation leap | expanding the power transmission network and driving better efficiencies leap | establishing and scaling up efficient power distribution capabilities government and regulatory driven industry driven levers a. attracting investments through favourable policies b. implementing efficient power generation technologies c. faster execution of power projects d. maintenance and overhauling of failing infrastructure a. attracting investments via public private partnership b. rapidly scaling up transmission infrastructure c. improving efficiencies through adoption of new technology a. blocking revenue leakage through automation b. scaling up distribution infrastructure in alignment with transmission expansion c. reducing losses by improving distribution infrastructure figure : pwc’s future electricity roadmap to (scenario ) source: [ ] international journal of sustainable energy planning and management vol. energy modelling as a tool for curbing energy crisis and enhancing transition to sustainable energy system in nigeria with all other projections. the fact that, [ ] showcased a better power projection for nigeria in demand, supply and sustainability or environmental concerns is a clear testimony to this. . combined energy supply and demand from other models (maed/message) to have a clearer view of the electricity projections from necal , the projections from previous models used by ecn were analyzed and compared with them. these models were secured through the international atomic energy agency’s sustainable energy development for sub-saharan africa as suite of energy analysis and planning tools. model for the analysis of energy demand (maed) and model for the energy supply strategy alternatives and their general environmental impact (message) are specific to the role they play in energy planning. maed is for energy demand while message is for energy supply and the associated alternative strategies and environmental issues. the two models were used in combination by [ ] to generate the electricity demand and supply projections for nigeria till the year . four scenarios used to generate the projections are discussed in details in [ ] in addition to other energy analysis related . gw with % capacity utilization, % transmis- sion and distribution (t&d) losses and about kwh annual per capita of electricity by . their projec- tions are divided into scenarios in leaps strategy based on transformation levers to be driven by indus- try, government and its regulatory bodies. the best scenario (no. ) is considered here for comparison with the electricity supply side of the best energy projections of necal , but limited to to figures as in the case of demand side comparison. unlike necal , the pwc projections saw the possibility of expanding of generation capacity, reducing t&d losses as the way of achieving higher energy access and consumption per capita. while necal is not explicit about per capita kwh consumption in the coun- try, the pwc projections factored that in relation to population growth to the year . therefore, contrary to the case of electricity demand, the best necal electricity supply and by implication all other energy projections may not be regarded as the true representa- tion of the best future energy system of nigeria. the claim made in the necal documentation that, the model tries to show the “scales of what are possible” by “exploring a range of available pathways” is not ade- quately achieved in the model’s best, and possibly true table : electricity projections from maed and message source: [ ] demand mw scenario reference ( %) , , , , , , high growth ( %) , , , , , , optimistic i ( . %) , , , , , , optimistic ii ( %) , , , , , , supply mw scenario reference ( %) high growth ( %) optimistic i ( . %) fuel type (%) coal . . . . . gas . . . . . hydro . . . . . nuclear . . . . . solar . . . . . wind . . . . . international journal of sustainable energy planning and management vol. ahmad garba khaleel, & prof. milindo chakrabarti tool of energy analysis in nigeria, some of the economic assumptions its best projections derived from are not in the best sustainability interest of the nigerian economy. the following table summarized the differences between the three projections and that of necal . it is obvious that the units in the tables ( , , & ) of the projections are quite different, specifically necal ’s values are in energy units while others are in power. however, the focus of our analysis is on elec- tricity projections in the models and their assumptions of the potential capacity of the energy system to adequately supply the needed power with considerable share of renewables. quantitative summary is attempted though may appear superficial as far as necal is con- cerned because similar analysis is needed for other energy vectors to fully cover the model. necal projections report over % growth of energy demand between and and % within similar period with other projections ( - ). power demand growth is % for sambo- , % for ezennaya- . on the other hand growth of energy supply for necal is above % ( – ) and about % ( - ), while power supply growth is about % for sambo- & little above % for pwc– . the shares of renewables (hydro, solar and wind) in the supply side are also different specifically in the projections of sambo- showing a decline from . % to . % between and . this can mainly be due to the focus of then government in developing gas power plants as reflected by the projected rapid growth of the gas share of electricity supply from . % to % within the same period. on the necal ’s projections, there is also a steady projected growth of the same renewables’ share from . % to % of the primary energy to be consumed within the same period, which is incomparable with that of sambo- (that is on electricity generation only). information specific to nigeria and the models. the focus here is on the projected numbers generated using these models and how they compare with the figures in necal , as superficial observation showed the symmetric pattern of the trends in nigeria’s electricity demand from both projections. however, when attention is turned to the energy balance of the [ ] projections, it is obvious that in all the scenarios, except optimistic i, there is excess of electricity demand over supply till around . optimistic i achieved excess supply in while the supply side did not feature the optimistic ii scenario thereby making the analysis incomplete. however, while we will not be computing and comparing the exact volume of electricity between the two projections, the shares of different vectors or fuels will give insight to another more important dimension of the analysis – sustainability of the energy system. it is obvious that the share of coal in the primary energy supply by will be only % less in the necal compared to its almost a decade old predecessors’ share in electricity supply. over all, the general concern raised in necal of relying on electricity imports in nigeria is not there as far as the previous models are concerned. above that, the models are even showing that the excess of demand over supply will disappear by in the optimistic i scenario and in the high growth and reference scenarios. it will be misleading to pass judgements on the level of sustainability of the electricity systems between the two projections, but if we take all figures on pro-rata basis, the message projections are more sustainable for nigeria than the necal . this is because, putting aside bioenergy, the shares of modern renewables of solar, wind and hydro by are higher in message with . %, . % and . % than in necal with . %, % and . % respectively. on this considerations, while necal is the most modern and advanced table : comparison of the four models differences in necal ezennaya- pwc- sambo- timing ( years) ( years) ( years) ( years) objectives integrated energy demand and supply projections with detailed fuel sources and emissions power demand projection based predicted load power supply projection with a targeted per capita kwh consumption combined power demand and supply projections with fuels sources. results steady growth of power demand, under capacity electricity generation and relying on power imports. steady growth of power demand. steady growth of power demand with ways to meet and improve upon the current situation. steady growth of power demand and supply, and the needed investment in generation without recourse to imports. international journal of sustainable energy planning and management vol. energy modelling as a tool for curbing energy crisis and enhancing transition to sustainable energy system in nigeria necal . that is to say, the problem is more with the modelling assumptions as the same model will produce far better projections than the current ones if the current and future conditions are well captured. similar projections are carried out for developed and developing countries alike in both medium and long term ranges with somewhat good results as can be seen in [ , , , , & ] with even more complex systemic challenges than simple electricity generation. it should however be in mind that, this work of ensuring the right assumptions are used rest more with the developing countries being helped than those assisting them. therefore the need for a better understanding as well as inclusion of these local conditions is the best way to go about, not only for energy modelling for developing countries but also for all other works that involve interactions between developed and developing countries. one way of doing that is introducing into the model the reflection of the local, regional, national and international policies, programmes and initiatives. another issue is increasing the role of renewable energy in the nigeria’s energy mix, particularly with the recent development of renewables in the global market that is forcing the parity of the renewables in an unprecedented manner. with these considerations, a more comprehensive modelling nature of necal which includes growth, development and environmental concerns, will be much more appreciated in the energy modelling journey of developing countries, not only nigeria. the real impact of these suggestions will be much clearer in the new energy projections that result when they are applied to the model and run. this is however not achieved in this work; perhaps it provides an avenue for further studies that will be of special interest to researchers in the energy future of developing countries, particularly those in africa. references [ ] oniemola, peter kayode. “powering nigeria through renewable electricity investments: legal framework for progressive realization.” journal of sustainable development law and policy (the) , no. ( ): - . https://www.ajol.info/ index.php/jsdlp/article/view/ / [ ] un general assembly. transforming our world: the agenda for sustainable development, a/res/ / , october , [accessed january ] at: https://sustainabledevel- opment.un.org/content/documents/ % agenda% for% sustainable% development% web.pdf. however, this would be highly appreciated, from sustainability viewpoint, if not for the presence of concurrent projected growth of coal’s share in the primary energy supply from – . to . % (surpassing the renewables) despite the global campaigns on climate action. though the units are different between the projections, the level of optimism shown in the supply potentials of the nigeria’s energy system is higher in other projections than those of necal . therefore, from these findings one may conclude that necal projections as considered in this study may bring higher energy access to nigerians but not in a sustainable manner as compared to its previous as well as subsequent counterpart projections. hence, there is the need for improving some of its basic assumptions, particularly those regarding the changing local economic realities in building its scenarios, so that they will reflect the sustainable and self-reliant direction of the global and local development efforts. . conclusion: policy implications & recommendations the paper aimed at reviewing the conceptual and historical evolution of energy modelling and the nigeria’s modelling experience over the years with most important models in nigeria currently being maed, message and the latest necal . it is established in both literature and experience that most energy models do not capture the features and issues of developing countries. the study further analyzed the best energy projections of necal with the view to finding out whether the model fully reflects the realities of the nigeria’s economy and that of similar developing economies in facilitating the transition to intensive renewable energy use in their development journey. based on the analysis carried out in this paper, it can be concluded that often at times, while trying to solve problems, more are created with even more complexities that further compound the situation. in this case, while trying to help countries solve their energy issues, more problems are created and compounded by developing models that do not pit their circumstances. the necal is a good model that failed to cover some of the most important requirements of the nigerian economy. undermining the electricity generation capability of nigeria as well as the role of renewable energy in the energy system at the best scenario of the model are the pronounced flaws identified in the https://www.ajol.info/index.php/jsdlp/article/view/ / https://www.ajol.info/index.php/jsdlp/article/view/ / http://https://sustainabledevelopment.un.org/content/documents/ % agenda% for% sustainable% development% web.pdf international journal of sustainable energy planning and management vol. ahmad garba khaleel, & prof. milindo chakrabarti planning and management ( ): - . dx.doi.org/ / ijsepm. . . 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[ ] korfiati, athina, charalampos gkonos, fabio veronesi, ariadni gaki, stefano grassi, roland schenkel, stephan volkwein, http://dx.doi.org/ . /ijsepm. . . http://dx.doi.org/ . /ijsepm. . . http://dx.doi.org/ . /ijsepm. . . http://dx.doi.org/ . /ijsepm. . . http://dx.doi.org/ . /ijsepm. . . https://doi.org/ . /ijsepm. . . http://dx.doi.org/ . /ijsepm . . http://dx.doi.org/ . /ijsepm . . http://dx.doi.org/ . /ijsepm . . http://dx.doi.org/ . /ijsepm . . http://www.ijstr.org/final-print/mar /analysis-of-nigerias-national-electricity-demand-forecast- - .pdf http://www.ijstr.org/final-print/mar /analysis-of-nigerias-national-electricity-demand-forecast- - .pdf http://www.ijstr.org/final-print/mar /analysis-of-nigerias-national-electricity-demand-forecast- - .pdf https://www.pwc.com/gx/en/growth-markets-centre/assets/pdf/powering-nigeria-future.pdf https://www.pwc.com/gx/en/growth-markets-centre/assets/pdf/powering-nigeria-future.pdf https://www.iaee.org/documents/newsletter-articles/ sambo.pdf https://www.iaee.org/documents/newsletter-articles/ sambo.pdf http://dx.doi.org/ . /ijsepm. . . http://dx.doi.org/ . /ijsepm. . . https://www.economist.com/the-economist-explains/ / / /why-nobody-knows-how-many-nigerians-there-are https://www.economist.com/the-economist-explains/ / / /why-nobody-knows-how-many-nigerians-there-are https://www.icafrica.org/fileadmin/documents/publications/africa_energy_atlas.pdf https://www.icafrica.org/fileadmin/documents/publications/africa_energy_atlas.pdf https://www.icafrica.org/fileadmin/documents/publications/africa_energy_atlas.pdf http://www.africaprogresspanel.org/publications/policy-papers/ africa-progress-report/ http://www.africaprogresspanel.org/publications/policy-papers/ africa-progress-report/ http:// . /en https://doi.org/ . /annurev.eg. . . https://doi.org/ . /annurev.eg. . . https://doi.org/ . /j.pecs. . . https://doi.org/ . /j.pecs. . . http://www.energy.gov.ng http://www.nigeria-energy-calculator.org http://www.nigeria-energy-calculator.org http://dx.doi.org/ . /ijsepm. . . http://dx.doi.org/ . /ijsepm. . . international journal of sustainable energy planning and management vol. ahmad garba khaleel, & prof. milindo chakrabarti and management ( ): - . http://dx.doi.org/ . / ijsepm. . . 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[ ] ebhota, williams s. “power accessibility, fossil fuel and the exploitation of small hydropower technology in sub-saharan africa.” international journal of sustainable energy planning http://dx.doi.org/ . /ijsepm. . . http://dx.doi.org/ . /ijsepm. . . http://dx.doi.org/ . /ijsepm. . . http://dx.doi.org/ . /ijsepm. . . http://dx.doi.org/ . /ijsepm. . . http://dx.doi.org/ . /ijsepm. . . https://doi.org/ . /ijsepm. . . https://doi.org/ . /ijsepm. . . https://doi.org/ . /j.erss. . . india’s impending energy crisis? full terms & conditions of access and use can be found at https://www.tandfonline.com/action/journalinformation?journalcode=taen international journal of ambient energy issn: - (print) - (online) journal homepage: https://www.tandfonline.com/loi/taen india’s impending energy crisis? neil j. hewitt to cite this article: neil j. hewitt ( ) india’s impending energy crisis?, international journal of ambient energy, : , - , doi: . / . . to link to this article: https://doi.org/ . / . . published online: jan . submit your article to this journal article views: view related articles view crossmark data https://www.tandfonline.com/action/journalinformation?journalcode=taen https://www.tandfonline.com/loi/taen https://www.tandfonline.com/action/showcitformats?doi= . / . . https://doi.org/ . / . . https://www.tandfonline.com/action/authorsubmission?journalcode=taen &show=instructions https://www.tandfonline.com/action/authorsubmission?journalcode=taen &show=instructions https://www.tandfonline.com/doi/mlt/ . / . . https://www.tandfonline.com/doi/mlt/ . / . . http://crossmark.crossref.org/dialog/?doi= . / . . &domain=pdf&date_stamp= - - http://crossmark.crossref.org/dialog/?doi= . / . . &domain=pdf&date_stamp= - - international journal of ambient energy, vol. , no. , http://dx.doi.org/ . / . . editorial india’s impending energy crisis? sustainable infrastructure development is a global challenge. as emerging nations strive to improve the quality of life for their citizens coupled with an emergence of greater personal wealth in both urban and rural communities, the desire for increased thermal comfort is a growing and yet understated challenge for electricity infrastructure that is already undergoing consid- erable expansion. a case in point that of india. an iea world energy outlook special report stated that ‘india’s power sys- tem needs to almost quadruple in size by to catch up and keep pace with electricity demand that – boosted by rising incomes and new connections to the grid – increases at almost % per year’. the role of air-conditioning is and will be signif- icant in both rural and urban areas with the potential to lack sufficient electricity supply capacity to meet expected demands. this is in spite of policies such as ‘ × power for all’, the ‘make in india’ campaign and proposed stronger building codes to reduce demands. in india, more people are in a position to afford air condi- tioners, which with current technologies can consume five times as much electricity as an evaporative air cooler. the market for air conditioners is already growing rapidly: sales of around million units in – rose to more than million units in – and very strong further growth is expected, with one estimate putting annual sales as high as million units by . therefore air conditioning is a major problem and it is coupled with an increasing need for electricity for appliances, domestic hot water usages and increases in space heating where appropriate. alternate approaches to providing space cooling, heating and hot water include solar water heating and/or biomass heat- ing coupled with absorption or adsorption chillers. however, there is not the possibility of supporting electric appliance usage growth without the incorporation of some form of heat driven electricity generator or significant photovoltaic capacity. thus, a complex system of heat sources and additional generators are required and such systems suffer from inappropriate costs. the complexity of such a system can be greatly simplified by the deployment of advanced solar collectors, hot and cold thermal storage and a rankine cycle capable of either electricity gener- ation and/or heating/cooling capacity or domestic hot water as required. thermal storage allows for time management and sup- ports flexibility of system use. furthermore, if such systems once developed can be adapted to regional solar energy resources, manufacturing, installation and maintenance capabilities, it will also serve regional economic growth in development, installa- tion and maintenance. in addition to the importance to india, within the uk, the abil- ity to provide demand side management with electrical heating and cooling systems via heat pumps and thermal energy stor- age has been noted. some scenarios imply a peak demand of gwfromair-sourceheatpumpswhichinturnsuggestsapprox- imately . million heat pumps at current performance rates. if such units become organic rankine cycles and generate power as well, a portion of the proposed uk market in batteries could also be utilised up to . gw. finally, the iea technology roadmap – energy storage noted that in order to support electricity sector decarbonisation, an estimated gw of additional grid-connected electricity stor- age capacity would be needed in the united states, europe, china and india. the report states that heat pumps, in particu- lar in high concentration urban areas, will allow them to provide thermal energy storage demand response services, for exam- ple, peak reduction and flexibility. thus, solutions (with modi- fications) can make a global impact with mass energy storage supporting demand side management through heat pumps and heat driven cycles. neil j. hewitt ulster university, uk nj.hewitt@ulster.ac.uk © neil j. hewitt http://www.tandfonline.com mailto:nj.hewitt@ulster.ac.uk << /ascii encodepages false /allowtransparency false /autopositionepsfiles false /autorotatepages /pagebypage /binding /left /calgrayprofile () /calrgbprofile (adobe rgb \ \ ) /calcmykprofile (u.s. web coated \ swop\ v ) /srgbprofile (srgb iec - 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/monoimagedownsamplethreshold . /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k - >> /allowpsxobjects true /checkcompliance [ /none ] /pdfx acheck false /pdfx check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ . . . . ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ . . . . ] /pdfxoutputintentprofile (none) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname () /pdfxtrapped /false /description << /enu () >> >> setdistillerparams << /hwresolution [ ] /pagesize [ . . ] >> setpagedevice inotropes in goal-directed therapy: do we need 'goals'? | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /cc corpus id: inotropes in goal-directed therapy: do we need 'goals'? @article{futier inotropesig, title={inotropes in goal-directed therapy: do we need 'goals'?}, author={e. futier and b. vallet}, journal={critical care}, year={ }, volume={ }, pages={ - } } 	e. futier, b. vallet 	published 	medicine 	critical care there is substantial evidence to demonstrate the benefits of goal-directed hemodynamic optimization using fluid loading or inotropic support or both to improve outcome during major surgery. however, until now, only limited pathophysiological data have been available to explain this benefit. the maintenance of adequate tissue perfusion and global oxygen delivery is an essential goal for therapy. in an interesting study, jhanji and colleagues provided additional data that emphasize the roles of… expand view on springer ccforum.biomedcentral.com save to library create alert cite launch research feed share this paper citations view all topics from this paper 	oxygen 	cell respiration paper mentions interventional clinical trial supernormal oxygen delivery for elderly surgical patients elderly patients with poor cardiopulmonary reserve tend to suffer higher risk and develop more complications following major surgery. quite a few researches have shown the benefits of… expand 	conditions	femoral fractures 	intervention	procedure guangzhou first people's hospital december - march citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency randomized controlled trial of intraoperative goal-directed fluid therapy in aerobically fit and unfit patients having major colorectal surgery. 	c. challand, r. struthers, + authors g. minto 	medicine 	british journal of anaesthesia 	 	 	 save alert research feed clinical review: management of weaning from cardiopulmonary bypass after cardiac surgery. 	m. licker, j. diaper, + authors k. bendjelid 	medicine 	annals of cardiac anaesthesia 	 	 	pdf save alert research feed intradialytic central venous oxygen saturation is associated with clinical outcomes in hemodialysis patients 	l. chan, h. zhang, + authors p. kotanko 	medicine 	scientific reports 	 	 	pdf save alert research feed volumentherapie bei hämorrhagie 	m. rössler, k. bode, m. bauer 	medicine 	der anaesthesist 	 	 save alert research feed arterial-jugular bulb differences in pco , lactate, serum sodium and c-reactive protein in neurocritical patients 	m. canitrot, s. ugarte 	medicine 	critical care 	 	 	 save alert research feed references showing - 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from 		 . . . on 		april , : : utc 	 rainy-season duration estimated from olr versus rain gauge data and the drought in southeast brazil sergio h. franchito and v. brahmananda rao centro de previsão de tempo e estudos climáticos, instituto nacional de pesquisas espaciais, são josé dos campos, brazil paulo r. b. barbieri fundação cearense de meteorologia (funceme), fortaleza, brazil clovis m. e. santo centro de previsão de tempo e estudos climáticos, instituto nacional de pesquisas espaciais, são josé dos campos, brazil (manuscript received february , in final form september ) abstract large precipitation deficits observed during the austral summer over the southeast region of brazil contributed to the worsening of the energy crisis that was occurring in the country, with unprecedented social and economic consequences. reliable information on the beginning of the rainy season was essential for the brazilian government to manage the energy crisis. the purpose of this study is to determine the rainy season in this region and to point out the risk of using outgoing longwave radiation (olr) data to estimate the beginning of it. the results show that when olr data are used the beginning and the end dates of the rainy season are wrongly anticipated and delayed, respectively. the present study aims to provide useful information for the management of the impact of adverse climate conditions such as the one in by basing the analysis on rainfall data instead of on olr. . introduction the southeast region of brazil (seb) is the most populous and plays an important role in the economy of the country, being characterized by high industrial ac- tivity, agricultural productivity, and hydroelectric gen- eration. although ramage ( ) did not consider south america (sa) as having a true monsoon regime, some studies revealed that a large part of subtropical sa experiences typical monsoon circulation (zhou and lau ; gan et al. ). particularly, seb shows characteristics of a monsoon system, where the rainy season is the austral summer and the dry season is the austral winter. during the austral summer the total rainfall was much lower than the normal values in southeastern, northeastern, and central brazil. large precipitation deficits observed over these regions contributed to the worsening of the energy crisis that was occurring in the country. to control the crisis, the brazilian government imposed rationing on the consumption of power in the beginning of the dry season (june ), which contin- ued until march . this led to an approximately % reduction in brazilian consumption of energy, af- fecting even other regions where there was no rationing (bardelin ). this energy crisis provoked significant social and economic consequences. to help the brazilian government to manage the en- ergy crisis, the minister of science and technology cre- ated a working group at center of weather prediction and climate studies (cptec) that was entrusted with the task of analyzing the situation of the water level in the power-plant reservoir and predicting the beginning of the rainy season. to this working group was given the responsibility of issuing bulletins in real time. many efforts were made to provide accurate information on the beginning of rainy season, which was essential for the brazilian government to manage the energy crisis. corresponding author address: s. franchito, centro de previsão de tempo e estudos climáticos, instituto nacional de pesquisas espaciais (inpe), cp , são josé dos campos, sp - , brazil. e-mail: fran@cptec.inpe.br may f r a n c h i t o e t a l . doi: . / jamc . © american meteorological society jamc several criteria were used to estimate the beginning of the rainy season. some studies used satellite-based out- going longwave radiation (olr) data to infer the pre- cipitation. although most of the studies that have been based on olr anomalies are on the subject of intrasea- sonal variability of precipitation in sa (nogues-paegle and mo ; paegle et al. ; carvalho et al. ; gonzalez et al. ; and many others), there are a few investigations using olr to identify and predict the onset of the rainy season in sa, mainly the onset in the amazon basin (kousky ; horel et al. ; marengo et al. b). other criteria to determine the beginning of the rainy season are based on winds (gan et al. , ) and rainfall data from rain gauge sta- tions (rao and hada ; cavalcanti et al. ). for the particular case of the severe drought of , marengo et al. ( a) used olr data to suggest that the rainy season over the basins generating electric en- ergy in seb begins between the end of september and beginning of october. cavalcanti et al. ( ), using daily data of precipitation, showed that there is large variability in the beginning of the rainy season in seb. however, on average it begins between the end of oc- tober and the beginning of november. so the two meth- ods used to determine the onset of the rainy season showed different results. since olr is a measure of high cloud, the criterion commonly used to determine the rainy season with olr data—values of olr lower than w m —indicates the presence of deep clouds that only indicate the probability of precipitation. how- ever, nonprecipitating high clouds like cirrus also show olr values lower than w m� , and consequently the method may lead to wrong estimations of rainfall. thus, a method to determine the rainy season based on rain gauges seems to be a more reliable indicator of precipitation characteristics. the purpose of the present study is to determine the beginning of the rainy season in seb based on rainfall data and to point out the risk of using olr data to estimate it. this study aims to provide information for the management of the impact of adverse climate con- ditions such as the severe drought of , which is a long-range objective of cptec. . data and methodology rainfall data of rain gauge stations for the period – were obtained from agencia nacional de en- ergia eletrica (aneel) and sistema integrado de gerenciamento de recursos hidricos do estado de sao paulo (sigrh). figure shows the location of these stations. olr data for the same period were obtained from ncep–ncar reanalysis (kalnay et al. ). pentad ( -day averaged) rainfall and olr data were calculated. to determine the rainy season using precipitation data for each rain gauge station (i ) for each pentad ( j ) for each year (k), the value of the accumulated precipi- tation at each days [ p(i, j, k)] was compared with [p (i)], which represents the -day accumulated precipi- tation if the annual rainfall was uniformly distributed during the whole year. starting from january, a ratio r(i, j, k) � p(i, j, k)/p (i) was calculated, where p (i) � p(i)/ , and p(i) is the mean annual rainfall. as a cri- terion for the beginning (end) of the rainy season, it was assumed that at least % of the values of r (i, j, k) are higher (lower) than (threshold value) at four consecu- tive pentads. although this criterion might seem arbi- trary, it was based on some important characteristics of the premonsoon and monsoon precipitation regimes. in the premonsoon period, rainfall may occur during some consecutive days (less than days). these episodes of intermittent rainfall are not related to the beginning of the rainy season. the monsoon period (rainy season) is characterized by regular (not intermittent) rainfall, which occurs during at least days continuously. how- ever, after around rainy days, periods with lack of precipitation may be related to the – day oscilla- tion (jones and carvalho ). after these breaks, rainy days are again observed. thus to characterize the rainy season we considered that the rainfall must occur continuously for a period of at least days but less than days. so we assumed that a criterion of the beginning of the rainy season is that at least one-half of fig. . station location map. the schematic map of the entire country of brazil including the location of the area of study is shown in the upper left of the figure. the letters sp, mg, rj, and es correspond respectively to the states of são paulo, minas gerais, rio de janeiro, and espirito santo. j o u r n a l o f a p p l i e d m e t e o r o l o g y a n d c l i m a t o l o g y volume the rain gauge stations ( %) in the region show rain- fall higher than the threshold value at four consecutive pentads ( days). to determine the rainy season using olr data, the method used by kousky ( ) was adopted. the cri- teria for the beginning (end) of rainy season were: (i) a pentad with olr mean value lower (higher) than w m� , (ii) at least of the earlier pentads with mean values of olr higher (lower) than w m� , and (iii) at least of the subsequent pentads with mean values lower (higher) than w m� . the number of the pentads and the respective calen- dar days relate as follows: pentad corresponds to – january, pentad to – january, . . . , pentad to – december. . results the prediction of the onset, intensity, and withdrawal of the monsoon constitutes a set of complex problems on which many researchers are working (see sperber and yasunari ). while the prediction of the arrival of the monsoon is a long-range goal, the present study has a more modest and reasonable goal of determining when the monsoon arrives, that is, to nowcast rather than to forecast. so we use two different methods to determine the onset of the monsoon and then compare the results. to evaluate which of the two methods bet- ter represents the onset and end dates of the rainy sea- son, we must first identify these dates. in this paper we use the definition of the rainy season given by gan et al. ( ). they determined the rainy season by consider- ing that the onset (end) is defined when the precipita- tion is more (less) than mm day� for at least six of the subsequent eight pentads. gan et al. ( ) used this definition to analyze the interannual variability of the rainy season associated with the monsoon over sa for an -yr period of precipitation time series ( / – / ). their results indicated that the earliest and latest onset dates occurred in – september and – november, respectively. the mean onset and the standard deviation for the onset were – october and days, respectively (see the two first columns of their table ). first, the results using precipitation data from aneel and sigrh are presented. as seen in fig. a, the seb shows distinct rainy and dry seasons. starting from pentad ( – september) the rainfall begins to increase. the change from the dry to the wet season occurs during pentad ( – october). according to the criteria described in section , the beginning of the rainy season occurs during pentad ( – october) and the end during pentad ( – march). the change from the wet to the dry season occurs around midautumn (pentad , – april). the period with highest number of meteorological stations with r � occurs from the beginning of december (pentad , – december) to the end of january (pentad , – january; fig. b). during the rainy season, the percent- age of meteorological stations with r � is higher than % in all of the pentads. the results shown above indicate that the onset date of the rainy season obtained using the method based on rainfall is in agreement with the mean onset date and the variability of the onset dates for the monsoon in sa obtained by gan et al. ( ). however, the end of the rainy season occurs pentads ( days) earlier than the mean demise date given in that study. figure shows the distribution of olr for the be- ginning and end of the rainy season in seb. by mid- september (pentad , – september), a deep con- vection band, which develops over amazonia (fig. a), advances southeastward, arriving in seb by the end of september and beginning of october (pentad , september– october; fig. b). by mid-october (pen- tad , – october), a large cloudiness band with olr values of w m� is found over the entire seb (fig. c). by mid-april (pentad , – april) the cloudiness band starts to move toward the equator, and fig. . (a) values of r(i, j, k) at each pentad, and (b) the per- centage of meteorological stations with r(i, j, k) � at each pen- tad. the dates correspond to the center of the pentads. may f r a n c h i t o e t a l . in the beginning of may (pentad , – may) the end of the rainy season in seb occurs (figs. d–f). these results are in general agreement with earlier studies using olr data, such as kousky ( ) and marengo et al. ( a), who found that the beginning of the rainy season occurred in the beginning of october and be- tween the end of september and beginning of october, respectively. the results presented above show that when olr data are used the beginning (end) of the rainy season occurs four (seven) pentads earlier (later) than when rainfall data are used. the lag is larger for the end of rainy season. this may be due to the movement of deep convection toward the equator that is slower than its progress southeastward (kousky ; marengo et al. b). gan et al. ( ) suggest that the slower move- fig. . distribution of olr values for: (a) pentad ( – sep), (b) pentad ( sep– oct, the beginning of the rainy season), (c) pentad ( – oct), (d) pentad ( – apr), (e) pentad ( – may, the end of the rainy season), and (f) pentad ( – may). j o u r n a l o f a p p l i e d m e t e o r o l o g y a n d c l i m a t o l o g y volume fig live /c ment of deep convection equatorward is perhaps due to the storage of soil moisture during the rainy season. in any case, results of the present study show that there is a substantial difference in the determination of the rainy season depending on whether olr or rainfall data are used. this discrepancy must be taken into ac- count whenever an accurate determination of rainy sea- son is crucial to establish strategies to deal with adverse climate changes such as the severe drought. the discussion above considered the mean start and end of the rainy season when precipitation and olr data are used. the same criteria (section ) were ap- plied to years of el niño and la niña events. during the period – , eight el niño and four la niña episodes occurred (additional information is available online at http://www.nws.noaa.gov). the el niño and la niña episodes and the pentad numbers correspond- ing to the beginning and end of the rainy season are given in fig. . during el niño events, the maximum delay of the beginning of the rainy season (pentad , – december) occurred in the / and / episodes, while in the / episode the rainy season extended up to the end of april (pentad , – april). the shortest ( pentads) and longest ( pen- tads) rainy seasons occurred respectively in the / and / episodes. in the case of the la niña events, the earlier end of the rainy season occurred in the / episode (pentad , – january). when the determination of the beginning, end, and duration of the rainy season using olr data is com- pared with the values obtained using precipitation data, large differences can be noted, as seen in fig. . for example, in the longest rainy season observed during el niño events, which occurred in / , the olr method delays the end of the rainy season by pen- tads. this wrongly overestimates by pentads the du- ration of the rainy season. the beginning and the end of the shortest rainy season observed in the / el niño event were respectively anticipated and delayed by pentads, thereby causing an erroneous increase of pentads in the duration of the rainy season with the use of olr data. during years of la niña events, large differences between the two methods are also seen. in particular, in the / episode there was an erro- neous delay of the end of the rainy season (pentad , – may) with olr data when compared with the result when precipitation data were used (pentad , – january). this discrepancy caused an apparent in- crease of pentads in the duration of the rainy season. one should, however, be careful in analyzing the results of the differences between el niño and la niña events because of the fact that the number of events is not large in the time series used in the present study. the conclusions should be reconsidered with further studies using a longer time series. the results of the present work show that there is an overestimation of the rainy season using olr data. the anticipation of the onset of rainy season using olr data is in agreement with the results of other studies on the energy crisis in seb (see marengo et al. a and cavalcanti et al. ). we tested the same criteria based on rainfall (as described in section ) for the meteorological stations located in the region of the basins responsible for the generation of electric energy in seb and found that the beginning of the rainy season in seb occurs at the end of november. the definition we used to determine the onset of the rainy season is a rigorous criterion in which the rainfall amount was enough for raising the low water levels in the reservoirs fig. . beginning, ending, and duration of rainy season during el niño and la niña events using precipitation (p) and olr data. also shown are the mean climatological data (mean). an asterisk indicates the shortest rainy season and the earlier beginning or end of rainy season; a double asterisk corresponds to the longest rainy season and the maximum delay in the beginning or end of rainy season. may f r a n c h i t o e t a l . during adverse climate conditions such as the drought of . another test of the method based on rainfall data was made, this time considering all the available meteorological stations of são paulo state (sp in fig. ). based on the same considerations about the pre- monsoon and monsoon precipitation regimes men- tioned in section , it was assumed as a criterion for the beginning of the rainy season that r(i, j, k) was higher than for at least three consecutive pentads or for two pentads followed by three pentads among four consecu- tive pentads. this criterion allowed an earlier onset of the rainy season when compared with that assumed in section , namely, r(i, j, k) higher than for four con- secutive pentads. this new definition is sensitive to the necessities of many sectors of society, such as agricul- ture, human activities, and even the electric sector (in situations different from that in the severe drought of , when a heavy precipitation in the rainy season was needed to raise the low levels of water in the res- ervoirs). despite this relaxation of the criterion, the onset of the rainy season still occurred between the end of october and beginning of november. thus, even when the onset of the rainy season is defined less strin- gently, the onset as measured by rainfall data occurs later than it does when measured by olr data. the overestimation of the rainy season using olr data may be attributed to fact that olr is a measure of high cloud, but not necessarily of rainfall. the criterion described in section —values of olr lower than w m� —indicates the presence of deep clouds that show only the probability of precipitation. since non- precipitating high clouds like cirrus also show olr val- ues lower than w m� , the method may overesti- mate the precipitation. although in the present study the validity of the rain gauge network data for estimation of precipitation is taken as granted, the method based on pentad rainfall data, described in section , contains some limitations. since the method is based on precipitation time series data, the estimation of the rainy season assumes that the rainfall behavior is similar to that of the past. de- spite this limitation, the onset date of the rainy season obtained using this method is in agreement with the mean onset date and the variability of the onset dates for the monsoon in sa (gan et al. ). another method to determine the onset of the rainy season, which uses climate model’s predictions, is based on winds. since the skill of climatic models to predict the wind components is better than to predict precipitation, monsoon indices based on wind changes may be used to estimate the rainy season in the future. this method has been applied with some success to the west-central re- gion of brazil (gan et al. , ). however, there is a need for similar tests for the various regions of the country. . conclusions in this study, the rainy season in seb was determined and the risk of using olr data for this purpose was demonstrated. in addition, the changes in the beginning and end of the rainy season during el niño–la niña events as derived from olr data were also examined. the study aimed to provide information for the man- agement of the impact of adverse climatic conditions such as the severe drought in . pentad rainfall data from rain gauge stations and olr data from ncep–ncar reanalysis were used. the results showed that when precipitation data were used, the beginning and the end of the rainy season in seb oc- curred respectively during pentad ( – october) and pentad ( – march). when olr data were used, the beginning and the end of the rainy season were wrongly anticipated (four pentads earlier) and de- layed (seven pentads later), respectively. when olr data were used for the determination of the rainy sea- son during el niño and la niña events, large differ- ences in relation to the precipitation data were also noted. in the case of el niño episodes, the beginning and the end of the rainy season were wrongly delayed and anticipated, respectively, up to pentads while in the case of la niña episodes, the duration of the rainy season was erroneously increased up to pentads. thus, the wrong inference of the extent of rainy sea- son with olr leads to the conclusion that these data should be used carefully, especially in the case of ad- verse climatic conditions such as the severe drought of , when accurate information about the beginning of the rainy season was essential for the brazilian gov- ernment to manage the energy crisis. since the date of the onset of the rainy season obtained with precipita- tion data showed a good agreement with that obtained for the monsoon in south america, the criterion used here may be useful to determine the rainy season in seb. the present study has attempted to provide meaningful and reliable information for decision mak- ers. note that in regions where surface rain gauge sta- tions are not available, the only available precipitation data may be those inferred from satellite data (by olr and other means). however, in view of our results, great care should be exercised in inferring quantitative rainfall. acknowledgments. thanks are given to dr. carlos a. nobre for the efficient organization of the energy crisis j o u r n a l o f a p p l i e d m e t e o r o l o g y a n d c l i m a t o l o g y volume group at cptec. thanks are also given to the anony- mous reviewers for useful suggestions. references bardelin, c. e. a., : the effects of rationing electric power in brazil in and with emphasis on the electric energy consumption (in portuguese). m.s. dissertation, polytechnic school, university of são paulo, pp. carvalho, l. m. v., c. jones, and b. liebmann, : the south atlantic convergence zone: intensity, form, persistence, and relationships with intraseasonal to interannual activity and extreme rainfall. j. climate, , – . cavalcanti, i. f. a., c. a. souza, v. e. kousky, and e. b. m. barbosa, cited : precipitation anomalies in the southeast region of brazil (in portuguese). [available online at http:// www.cptec.inpe.br/energia/saiba/portalpop .shtml.] gan, m. a., v. e. kousky, and c. f. ropelewski, : the south america monsoon circulation and its relationships to rainfall of over west-central brazil. j. climate, , – . ——, v. b. rao, and m. c. l. moscati, : south american monsoon indices. atmos. sci. lett., , – . gonzalez, p. l. m., c. s. vera, and b. liebmann, : charac- teristics of the intraseasonal variability of precipitation over eastern argentina. proc. eighth int. conf. on southern hemi- sphere meteorology and oceanography (icshmo), foz do iguacu, brazil, instituto nacional de pesquisas espaciais, – . horel, j., a. hahmann, and j. geisler, : an investigation of the annual cycle of convective activity over the tropical americas. j. climate, , – . jones, c., and l. m. v. carvalho, : active and break phases in the south american monsoon system. j. climate, , – . kalnay, e., and coauthors, : the ncep/ncar -year re- analysis project. bull. amer. meteor. soc., , – . kousky, v. e., : pentad outgoing longwave radiation clima- tology for the south american sector. rev. bras. meteor., , – . marengo, j. a., l. m. alves, c. a. c. castro, and d. mendes, cited a: information on the beginning of the rainy season in the southeast, west-central and south of northeast regions, which are affected by the energy crisis (in portuguese). [available online at http://www.cptec.inpe.br/energia/saiba/ iniciochuvas.shtml.] ——, b. liebmann, v. e. kousky, n. filizola, and i. wainer, b: onset and end of the rainy season in the brazilian amazon basin. j. climate, , – . nogues-paegle, j., and k. c. mo, : alternating wet and dry conditions over south america during summer. mon. wea. rev., , – . ——, l. a. byerle, and k. c. mo, : intraseasonal modulation of south american summer precipitation. mon. wea. rev., , – . ramage, c. s., : monsoon meteorology. academic press, pp. rao, v. b., and k. hada, : characteristics of rainfall over brazil: annual variations and connections with southern os- cillation. theor. appl. climatol., , – . sperber, k. r., and t. yasunari, : workshop on monsoon climate systems: toward better prediction of the monsoon. bull. amer. meteor. soc., , – . zhou, j., and k.-m. lau, : does a monsoon climate exist over south america? j. climate, , – . may f r a n c h i t o e t a l . focus issue: the global energy crisis: opportunities and challenges for mountain areas dear readers, at the beginning of , the fukushima nuclear disaster and the challenge of meeting ever-increasing energy needs worldwide led greater sustainability of the energy sector to become a dominant theme in political debates, the media, and civil society around the world. today, the international financial crisis has replaced energy concerns in the headlines. but the energy challenge remains as acute as before. the stakeholder forum of the earth summit rio + confirmed the urgency of the issue and placed the ‘‘energy crisis’’ on its agenda, also pointing out that it is a key issue in a ‘‘green economy’’. this issue of mrd is the third in years that is devoted to sustainable production and use of energy in mountain areas (see also mrd vol no and mrd vol no ). it aims at contributing to the debate about how mountains are affected by the global energy crisis and whether the crisis might offer opportunities for mountain communities. the papers devoted to the energy theme in this issue— mountaindevelopment, mountainresearch, and mountainnotes papers—cover a broad range of topics, thus reflecting the multidimensional challenge that mountain communities face today in light of the global energy crisis. the papers also highlight the need for a comprehensive understanding of the human–energy–environment nexus and for approaches that take into account the increasing connectedness between energy situations at the local, national, and global levels. in his mountaindevelopment paper, katsoulakos illustrates how energy saving and more efficient use of regional fuelwood could reduce dependency on external, non-renewable energy sources and thus contribute to overcoming energy poverty in a mountain area in greece. in the mountainresearch section, the paper by erlewein and nüsser focuses on the challenges and opportunities of the clean development mechanism (cdm). the authors investigate the effectiveness of large cdm hydropower projects in the indian state of himachal pradesh and show that the cdm is a highly ambivalent strategy. in a paper on local energy resources and consumption patterns in the pamir-alai mountains, förster and co-authors use an innovative research approach to depict relations between energy resources, land use, and livelihood assets. kaburi and medley’s paper provides insights into a totally different energy context in africa: applying a cultural- political ecological viewpoint and an experiential learning process, the study assesses the fuelwood situation, the diversity of fuelwood resources, and local people’s perceptions in the buffer zone of mount kenya forest reserve. two energy-related articles in the mountainnotes section take up policy issues: abegg shows that mountain regions have the power to shape their own energy future. he presents the vision of ‘‘energy self-sufficiency’’ currently promoted by the international commission for the protection of the alps (cipra) and applied in a few european alpine regions already. plets and co-authors describe how mountain regions—here the altai region—can be affected by large international energy projects when planning and implementation are not guided by transparent and integrative strategies. gazprom intends to construct a pipeline through the altai region that endangers the rich cultural heritage of this area; the authors suggest a strategy to integrate heritage conservation in the construction plan. this paper is complemented by yuri badenkov’s perspective on the planned pipeline in the mountainviews section. apart from these papers on the ‘‘global energy crisis,’’ the mountainresearch section contains additional informative papers. katel and schmidt discuss how local residents use forest resources in a national park in bhutan and how restricted access and inadequate incentive schemes shape their perceptions about the protected area. yang and co-authors examine how recent developments in china are influencing indigenous dongba papermaking in the naxi highlands and what role the montane forest plays in maintaining this traditional handicraft. tang and co-authors investigate the habitat fragmentation and degradation of a highly endangered endemic tree, michelia coriacea, in southeastern yunnan, china. onta and resurreccion focus on the often neglected gender and cultural dynamics of climate change adaptation processes; they examine whether such processes exacerbate or alter gender inequalities and inter-caste dependencies in the humla district, nepal. finally, pütz and co-authors investigate tourists’ attitudes towards artificial snow-making in swiss destinations. the results show that snow reliability is only one criterion for choosing a destination: the alpine landscape and a wide choice of activities are even more important factors. this paper is a sequel to the paper by rixen et al in mrd vol no . in a third paper in the mountainnotes section, a group of international researchers (mcdougall et al), present management practices in mountain regions around the world with the aim of drawing key lessons about how to prevent plant invasion in mountain areas. we hope that you will find this focus issue on the global energy crisis and other sustainable mountain development themes useful and interesting. hans hurni, editor-in-chief susanne wymann von dach, and anne zimmermann, associate editors mrd editorial office, centre for development and environment, university of bern, switzerland mrd-journal@cde.unibe.ch open access article: please credit the authors and the full source. editorialmountain research and development (mrd) an international, peer-reviewed open access journal published by the international mountain society (ims) www.mrd-journal.org mountain research and development vol no nov : http://dx.doi.org/ . /mrd. � by the authors opening the indonesian bio-fuel box: how scientists modulate the social | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /jantti. corpus id: opening the indonesian bio-fuel box: how scientists modulate the social @article{fatimah openingti, title={opening the indonesian bio-fuel box: how scientists modulate the social}, author={y. fatimah and s. yuliar}, journal={innovaint. j. actor netw. theory technol. innov.}, year={ }, volume={ }, pages={ - } } 	y. fatimah, s. yuliar 	published 	engineering, computer science 	innovaint. j. actor netw. theory technol. innov. abstract this article employs the notion of translation introduced in ant literature to study the current bio-fuel development in indonesia. despite the presence of some activities by scientists, businessmen, policy makers, and farmers, diffusion of bio-fuel innovation seems to remain very limited. the article aims at understanding the bio-fuel development trajectory by seeking to disclose a variety of elements that shape the trajectory. we also make use of the notion of 'qualculation', to… expand view via publisher igi-global.com save to library create alert cite launch research feed share this paper citationsbackground citations view all topics from this paper 	british informatics olympiad citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency engineering the jatropha hype in indonesia 	s. afiff 	engineering 	 	 	pdf 	view excerpt, cites background save alert research feed riding the hype: the role of state-owned enterprise elite actors in the promotion of jatropha in indonesia 	d. simandjuntak 	economics 	 	 	pdf save alert research feed trading in discursive commodities: biofuel brokers’ roles in perpetuating the jatropha hype in indonesia 	j. vel 	economics 	 	 	pdf 	view 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outlined in our privacy policy, terms of service, and dataset license accept & continue the review of regional studies on the economics of energy allocation merlin m. hackbart, charles w. hultman, and james r. ramsey* the arab petroleum embargo in late , the gasoline shortage and rising fuel prices experienced by consumers in the last few years, and the difficulties encountered by some sectors in securing certain indus trial materials focused attention in recent years on the possibility of a serious energy shortage and consequent dislocations in the u.s. econ omy. furthermore, the "energy crisis" revealed the lack of coordinated state and federal policies for dealing with shortages and energy alloca tions. market restrictions, such as the opec cartel which brought on the energy crisis, are possible in the future. hence, policies and pro cedures for allocating fuel during energy cut-offs and shortfalls must be developed by national and state governments if impacts are to be minimized. during the petroleum shortfall, the federal government allocated a quantity of fuel to state energy offices for further distribu tion to industries within each state. in general, states did not have analytical procedures or formal policies for allocating the additional fuel. purpose a difficulty in analyzing the impact of a fuel shortage on the state economy and establishing allocative procedures is the large amount of data which must he reduced to management proportions. one approach to this data management problem is the use of an input-output model. such a model can he used to provide a substantial amount of informa tion about the economic impacts, both direct and indirect, of a fuel shortage on a state economy. in this study, the impact of a petroleum shortage on state industrial output and employment are estimated using such a model. xhis paper includes a discussion of: ( ) the procedures employed, and ( ) the empirical results obtained from the application of the ken tucky input-output model in combination with linear programming techniques to establish a petroleum allcication system which would minimize the impact of petroleum cutbacks for kentucky. the pro cedures employed in the kentucky study could be applied in other states and for other energy shortages, such as natural gas, if a suffi ciently disaggregated input-output model existed. *associate professor and professor of economics, university of kentucky; and assistant pro fessor of economics, middle tennesee state university, respectively. volume , number nature of the modeh the kentucky input-output table displays an array of interindustry flows of goods and services among sectors in the kentucky economy. the flows depict industry or sector sales to all other industries or to final users (i.e., government, consumption, investment, and inventories). consequently, all sector outputs are accounted for hy the i-o table. for this study, the kentucky - table was converted to a model via the behavioral assumptions of production function stability, constant re turns to scale, and no substitution of production factors to carry out the petroleum supply cutback and allocation analysis.^ the -sector kentucky model was aggregated to a model of sectors for this analysis. the aggregation wa& necessitated due to the smallness of cer tain sectors and the lack of sector specific wage data required for certain calculations described in this paper. formally, the aggregated dtsector kentucky mode? can he defined as follows: xi = total production in industry i aij = ratio of dollar of input used hy industry j and produced hy industry i yi = final demand in industry i production in each kentucky industry is either sold to final con sumers or bought hy other industries. given this, an expression for industry i relating final demand to production is: x, - aijxi =y,. ( ) j = l collecting the xis to form a vector x and yis to give a vector y and aijs to form a coefficient matrix a allows ( ) to he written: x - ax = y, ( ) which can he further simplified to: (i - a)x = y. ( ) this expression gives all final demands y, and the production necessary to deliver these ys can be expressed: x = (i — a)-^y. ( ) methodology the year was selected as a base year for analyzing the impact of a cutback in petroleum supphes on the kentucky economy. by project- the review of regional studies ing an array of state final demands (y) for , total production (x) was computed by substitution into ( ) above. similarly, given (x), intersectoral flows were estimated by pre-multiplying the x vector times the coefficient matrix, a. the resulting meitrix represented kentucky economy final demand and production transactions for . in the sec tions which follow, the respective methodologies utihzed for estimating the employment and output impacts of a petroleum cutback as a guide for petroleum allocation policy utilizing linear programming techniques in combination with i-o are reviewed. output impact. in the kentucky input-output model, row of the a matrix represents the petroleum sector. (consequently, each element of this vector represents a petroleum utilization coefficient as it repre sents the direct petroleum input per dollar output by sector. multiplying these coefficients, aijs, times the respective sector output levels, the xjs, yielded a value c which can be represented as in ( ): a ,ixi -|- , x -|- ... , x = c. ( ) c, then, represents the total amount of petroleum (in dollars) directly required to produce the sector output totals. by changing the equality sign of ( ) to a less-than-or-equal-to sign, the sum of oil usage was constrained to a level no greater than the total amount available. for analyzing the impact of a petroleum availability cutback on output, c was then assumed to be reduced to reflect the petroleum cutback. notationally, the reduced petroleum availability can be represented as c and ( ) becomes ( ) reflecting the petroleum cutback. , x -j- , x -|- ... , x = c' ( ) a constraint was then imposed on each se<;tor independently so that constraint ( ) was expanded into a series of one-element relations written as follows: , x = ci' , x = c ' , x = c ' from ( ) it can be shown that given a final demand y there is only one x which would solve the system. the hnear programming problem was initially written as fouows: volume , number maximize z = s xi i = subject ̂to: (i — a) x = y (i) bx = c (ii) and x = , (iii) ( ) where b is row of a as described in ( ). here total production in the state (sum of the xi) is maximized subject to the constraint of the input-output relations and the added constraint on oil supplies. in order to achieve a linear programming solution, it was also necessary to specify an upper limit on projected final demands. fdu represented the vector of sectoral final demands. the new problem was to: maximize z — xi i -= subject to: (i — a)x — y = (i) y = fd„ (ii) bx c (iii) x (iv) ( ) where y = the amount of final demand actually delivered. solving the linear programming system ( ), total production for the state, for each industry, and final demand delivered could have been estimated. however, a possible consequence of the absence of an alloca tion scheme for distributing oil, given a petroleum cutback and that total state production was to he maximized, was that entire industries could have been eliminated in the solution as far as supplying final demand. this situation was economically untenable hut was possible with the final demand constraint stated simply as: y = fda ( ) therefore, an alternative was to place a lower limit on the above con straint, such as: the review of regional studies fdl = y = fdo ( ) where fdl was an assumed lower limit on final demands and fd„ repre sents the previously specified upper limits. the final step for estimating output impacts involved the development of dual activity variables or shadow prices. a dual variable shows the amount by which the objective function will change for a unit change in the appropriate resource constraint. the original solution variables were production figures, x, and final demand figures, y. these numbers generally refer to the "columns" of the linear programming arrangement whereas the dual variables indicate the importance of the rows or con straints. in the construction of: maximize z = xi i = subject to: (i — a)x — y = y ̂ fdu (ii) bx ̂ c and x, y ̂ (iv) ( ) the dual variables are associated with the rows of line i, rows of > line ii, and row of line hi of ( ). specifying x, y = simply states that only zero or positive values are allowed in the solution. the concern of this study was with impacts of changes in oil supplies, therefore, of concern was the dual variables of line iii. it is important to note the difference between the system ( ) with a constraint such as that in line iii and a similar system with the follow ing constraints: a ,ixi = ci' , x = c ' , x = c '. volume , number each component of the summation of line iii in ( ) is now a separate constraint. given the values for ch, cz', ... cis', a modified system using all rows of ( ) was simultaneously solved. if the ci's are binding then the dual variables define the expected change in each sector's output attributable to a marginal increase in the quantity of oil allocated to each sector (i.e., the marginal value of an additional unit of oil to each sector). more specifically, each element of the resulting vector of dual variables, , represents the expected change in each sector's output given a $ . reduction in the petroleum available to that sector or in dustry. vector is of dimensions x . the dual variables were used in the empirical results which are summarized in a following section. employment impact. in addition to output impacts as indicated by the dual variables, the input-output model was used to estimate the em ployment impacts of reductions in petroleum supplies. using the pre viously defined notation, now let v = a value-added coefficient vector for kentucky industries v' = a labor coefficient row vector v" = residual value-added coefficient matrix. the value-added coefficients in the v vector represented the total value added (labor, capital, land, and entrepreneurship) by industry per $ . output. the vector was disaggregated into a (labor) vector and a v" (residual) vector. to disaggregate v, it was necessary to determine labor's share of value added.^ to find the appropriate labor share of value added in kentucky, average factor shares for each aggregate sector (manufacturing, non- manufacturing, and utilities) were utilized.' factor shares for these major sectors had been estimated in an earlier study and are summarized in table . in disaggregating the v vector into vh the appropriate labor share presented in table was multiplied by the v vector of value-added coefficients. the columns of the (i — a) ' matrix contain coefficients showing the direct and indirect requirements by industry for an expansion of final demand by $ . for each sector. table allocation of factor shares by industry capital manufacturing non-manufacturing utilities source: harold k. charlesworth and william g. herzel, kentucky gross state product, , (lexington, kentucky: office of business development and government services, ), p. . the review of regional studies pre-multiplying (i — a)-^ by the vectoi- will yield a row vector of labor value-added multipliers; or (i - a)-^ where: l = direct and indirect labor requiremeiits per dollar of output by sector finally, the multiplication of each element in , the expected changes in each sector's output, given a reduction in petroleum supplies, times the corresponding sector element in the vector l, the direct and indirect labor requirements, will yield the change in each sector's output resulting from an oil cutback which can he attributed to labor. that is. ©jlj = q (j = . ■ • n) where: j = jth elements of vector ij = jth elements of the l vector q = change in each sector's labor requirement resulting from a petroleum cutback q can he transformed into an employment impact estimate in terms of numbers of workers by division by the mean wages for each sector for the given period or time. or, n =- where: w = average wages for each sector n = employment impact results the above-outlined procedures, equations through , were used to estimate both the output and employment impacts of a given p^roleum cutback. to derive these estimates, an array of final demands (y) were projected for the state for . the projected final demand was $ , billion and total production was computed (by [ ]) to be $ , billion. as previously indicated, these figures describe the situation in the state economy given no constraints. it should also be noted that the original cutback in oil supplies was arbitrarily assum(jd to be percent. given this constraint, total state production declines to $ , billion and final demand declines to $ , billion. finally, note that the calculated volume , number dual variables show the cost to the state in terms of output of a $ . reduction in petroleum to each industry. to avoid infinitesimal employ ment impact figures, the dual variable was arbitrarily converted to show the impacts of $ , . reduction in petroleum supplies. the estimated output and employment impacts are presented in tables and , respectively. for example, as seen in table , if the petroleum available to the cigarette and cigar industry (sics and ) is re duced by $ , . then the total output for the state will be reduced by $ , , . a rational allocative technique could be developed based upon the im pact the reduction in petroleum has on industrial output. hence, given a reduction in petroleum supplies allocative efforts should be made to guarantee fuel supplies for those industries near and at the top of table . it is these industries for which the loss in state output is the greatest for fuel cutbacks. at the same time, however, it must be remembered that the figures in table provide only a first general guide to the cost in terms of output of reducing the availability of petroleum to each of the state's industries. the possibility of other offsetting factors must be recognized. for ex ample, some industries might be able to absorb a small reduction in petroleum availability by using existing supplies more efficiently. second, some industries initially affected adversely by the indirect impact of petroleum shortages might be able to secure essential input from outside the state. as shown in table , the reduction in state employment resulting from a $ , . cutback in petroleum supplies to the cigarette and cigar in dustry would be . workers. it can be concluded that the industry rankings presented in table offer a logical distribution procedure for allocating oil cutbacks. it would follow that an effort should be made to guarantee fuel supplies for those industries near or at the top of table since it is for these industries that the loss in emplojnnent is greatest if petroleum supplies are reduced. conclusions the industry rankings presented in tables and are, as would be expected, very close. in fact, the computation of a rank-order correlation coefficient shows a + . relationship between the two different rank ings of impacts from the reduction in petroleum supplies.® a perfect correlation between the rankings would be indicated by + . . the results presented in tables and must be considered tentative and interpreted with caution. first, the findings are subject to the data limitations of input-output analysis.^ second, due to the openness of a state economy, it must be assumed that the interregional trade coeffi cients are stable.® any change in trade patterns to supplement energy resources would, of course, mitigate projected impacts. the review of regional studies changes in state output given a ) , change in petroleum to each industry output change per yearindustry cigarette and cigar manufacturing tobacco stemming and redrying amusements communications medical and educational services business services insurance lumber and wood printing and publishing apparel finance retail trade primary metals real estate hotels and lodging textile mill products government enterprises electric, gas, water, and sanitation fabricated metals personal services wholesale trade stone, clay, glass coal mining other transportation equipment mining, other electrical machinery construction paper and allied products machinery except electrical automotive repairs tobacco motor vehicle and equipment agriculture, other food and kindred products professional and scientific instruments motor freight transportation paints and allied products miscellaneous manufacturing plastics furniture and fixtures chemicals petroleum products leather products $ , , . , , . , , . , , . , , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , . , , - - - , - , , - , charles hultman, tom patrick, and james watts, "energy in the ken tucky economy: a preliminary report," , (an unpublished paper), p. . source: volume , number table change in state employment resulting from a $ , change in petroleum to each industry industry change in employment per year , - - , - , ^ , , - - cirgarette and cigar manufacturing tobacco stemming and redrying amusements real estate business services finance retail trade medical and educational services communications insurance hotels and lodging government enterprises lumber and wood apparel and other printing and publishing wholesale textile mill products personal services fabricated metals electric, gas, water, and sanitation agriculture, other tobacco primary metals auto repairs coal mining electrical machinery stone, clay, glass mining, other motor freight and warehousing construction professional and scientific instruments paper and allied products machinery except electrical paints and allied products food and kindred products other transportation equipment furniture and fixtures plastics miscellaneous manufacturing motor vehicle and equipment chemicals petroleum products leather products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . given these cautions, the results presented offer two strategies for the allocation of petroleum: ( ) allocation so as to maximize state industrial the review of regional studies output, and ( ) allocation so as to maximize state employment. alloca tion based on either strategy has much meirit. yet while it may seem initially that theire could be no objections to allocations based on maximizing either employment or output, in fact, other priorities could be established. for example, an allocative priority system might be based on the nature of the output of the respective in dustries. thus, it could probably be argued that a higher priority should be given to medical and educational services (sic and ) than to the amusement industry (sic ) regardhjss of the impact on employ ment or output. the allocative scheme described, then, does not offer value judgments regarding which objective should be achie\'ed in coping with an energy shcmtage. it simply provides a rational pidority system to achieve an objective which has already been specified. in the end, the planning agencies must combine their perception of social needs and desires with such tools of analysis as input-output tables and linear programming in order to implement an acceptable allocative scheme. footnotes isince the cost of constructing an input-out- put table employing primary data is generally prohibitive for a state, the present model is based on secondary data. the u.s. input- output table is the source of the basic data. the data have been modified by use of survey and interviews to reflect the methods of pro duction for kentucky industries which vary considerably from those used in the u.s. input- output model. =slee w. leontief, input-output economics new york: oxford university press, ); and william h. miernyk, the elements of input-output analysis (new york: random house, ), for further discussion of these behavioral assumptions of input-output model ling. the kentucky model uses data for gross outlays (obtained from state corporate income tax returns, the internal revenue ser vice, and the u.s. bureau of census). for the non-manufacturing sectors, two assumptions were made: ( ) production data are not sig nificantly affected by inventory variation ex cept in the trade sectors, and ( ) receipts were considered to be production. finally, it is noted that»the model has been adjusted to account for jdrice changes from to . ■i.previously, economic research has estab lished different weights for labor's share of value added in the production process. for example, kendrick and nelson in separate works assign . as the weight for capital's share and . as the weight for labor's share. however, solow's research reveals a weight of . for capital and . for labor. see john kendrick, productivity trends in the united states (princeton: princeton university press, ); richard r. nelson, "aggregate func tions and medium-range growth projections," america n economic review, liv, no. , (sep tember ), p. ; and robert solow, "tech nical change and the aggregate production function," review of economics and statistics, xxxix., no. , (august ), pp. - . (the solow figures of . and . are taken from the cheneny, hollis, arrow, minhas, and solow jirticle in same journal, august . however, this figure is based upon solow's work wliich we are citing.) ■■•harcld k. charlesworth and william g. herzel, kentucky gross state product, (lexington, kentucky: office of business de velopment and government services, ), pp. - . "let, h!o: there is no relationship between the ranking of results presented in tables and . h!j: reject the null hypothesis. > for this test of significance (n = ), the rank correlation coefficient can be tested using the t distribution. for a percent level of sig nificance, the critical t is approximately . and the computed t is . ; hence, the null hypothesis is rejected. "see note above. "for a more detailed discussion of the stability of trade coefficients, see m. jarvin emerson, f. charles lamphear, and leonard d. atencio, "toward a dynamic regional ex port model," the annals of regional science (deceml)er ), pp. - . challenges for future energy usage eckhard rebhan heinrich-heine-university düsseldorf institute for theoretical physics survey . glance into the history of energy usage . present situation population growth shortage of resources environmental damages and hazards . identification of the biggest energy spenders . boom of renewable energies . promising options . challenges . glance into history of energy usage energy sources in past times: renewable (plants, animals, wood, charcoal, water, wind) power and heat from fire and muscles → slavery unusually benign climate for the last thousand years → cultural evolution population thousand years ago: a few million in ad: million start of industrialization about years ago start of coal era coal fired steam engine of thomas newcomen ( . % efficiency) steam engine of james watt ( % efficiency) advent of electricity dynamo of werner von siemens → breakthrough of electr. motor light bulb of thomas alva edison first electric power station (new york) first electrically driven subway (london) start of oil era first drilling for oil (edwin l. drake) foundation of standard oil company (john rockefeller) advent of the automobile otto engine (nikolaus a. otto) first automobile with combustion engine (call benz) advent of natural gas first working gas lamp (johannes p. minckeleers) first gas company (london, friedrich a. winzer) first public gas illumination (london) broader use of gas started about years ago advent of nuclear energy first nuclear power station in obninsk (russia) nuclear power station in calder hall (england) chernobyl catastrophe population year time difference . billion . billion billion billion billion growth of world population year world population e/ej p/w . billion . . billion . billion worldwide energy consumption grew even faster e = total energy consumption per year p = energy consumption per capita per second ej = exajoule = j, w = watt . present situation evolution of world population about billion, maximum – billion nuclear coal oil gas water non-commercial population energy consumption energy consumption grew faster than population daily energy requirement of one person: kcal corresponding to w permanent power supply ( w radiated away) regional differences in power usage per capita region usa brd china africa [w] ( without south africa) running short of energy resources % of energy consumption from fossil combustion peak oil problem and oil supply today . billion automobiles, fuel essentially from oil . billion automobiles expected regional differences in annual per capita oil consumption region usa brd china india barrels . . . annual oil production and oil discoveries reversal point gb = gigabarrel g hubbert curve depletion-mid-point peak oil in germany in usa worldwide with opec and former su excluded not yet in iraq, kuwait and saudi arabia worldwide peak oil expected between and expected consequences: sharp rise in price and energy crisis peak oil of nations xpresent price per capita oil production rate per capita peak oil per consumer oil peak even before oil reserves in : gigabarrels (bp statist. rev. of world energy) annual production rate: gigabarrels projected reserve life time : years ( years taking account of rising demand) crude oil consists of about chemical constituents → pharmaceuticals, solvents, fertilizers, pesticides, paints and coatings, detergents, plastics, ..... what a shame to just burn it! supply of coal, gas and uranium energy carrier peak of production in reserve life span oil - y natural gas - y coal – y uranium ? – y environmental problems caused by conventional energy usage ● pollution, erosion, contamination and flooding of soils ● pollution and contamination of waters ● local and global pollution + contamination of atmosphere with consequential damage to fauna and flora ● environmental burdens through the release of heat ● local and global climate changes, especially through man made enhancement of greenhouse effect since in atmosphere concentration of methane doubled, of co increased by % temperature and co concentration correlated co in ppm temperature variations in °c years before today today e increase of temperature sea level last years . °c . cm next years – °c – cm percentage of the different forms of energy (germany in ) mechanical energy industrial heat room heating light, information + communication % % % % percentage of end energy consumed by different users (germany in ) traffic homes small-scale consumers industry % . % % . % . identification of the biggest energy spenders percentage of the different kinds of primary energy (worldwide) oil gas coal hydroelectric nuclear renewables % . % . % . % . % . % . / energy losses from source to final usage → energy saving! . energy saving especially important in traffic and heating traffic: biggest spender, only % end energy finally used ( % of primary energy) (other fields: about %) more than % of end energy → heat . boom of renewable energies hydroelectric power ● water storage power plants ● damless hydraulic power stations worldwide %, germany % electricity production water powered worldwide big enhancement possible (not in germany) wind power worldwide %, germany %, denmark % electricity prod. wind powered up to mw per turbine within years wind energy price reduction by factor . , but still subsidized financial break even expected in – first offshore wind farm in denmark → high potential expected solar power ● heating of air in homes and greenhouses ● heating of water in solar thermal collectors ● cooking ● water distillation, desalination and disinfection ● solar chemical processes solarthermal applications (non-electric) solar electricity ● photovoltaic electricity ● solar thermal power plants photovoltaic electricity no direct sunlight needed, very flexible --> from pocket calculator to multi-mw pv-station cell efficiency %, durability – years energetic amortisation after . – years --> pv not completely co free cost reduction by factor > since , still too expensive (high subsidy) new materials (organic polymers, metal alloys) --> higher efficiency, lower costs concentrator cells --> large power from small systems solar thermal power plants direct sunlight needed --> southern countries high efficiency, energetic amortization after few months medium subventions, higher manufactoring numbers --> steep reduction in costs photovoltaic electricity generation in germany bioenergy energy in tons biomass = energy in ton petroleum biomass --> production of heat, electricity, liquid fuels and biogas first generation biofuels : not sufficient and sustainable (shugar cane, corn etc.) --> food versus fuel debate second generation biofuels: sustainable, (non-food crops, waste biomass) financially not yet competitive (subsidy) --> biogas and liquid fuel (sundiesel) third generation biofuels: algae geothermal heat (widely neglected) close to earth´s surface heat from sun → heat pumps in deeper layers heat from radioactivity → electric power + industrial process heat concentrated to areas of geothermal anomaly appropriate for base load power plants high drilling costs → high financial risks contribution to worldwide power supply < % high potential: supply of whole mankind for years . promising options co sequestration role of coal will increase, but highest co emissions, exceeding those of oil by factor . and of gas by factor . enhancing efficiency not sufficient: same emissions as gas fired plant of % efficiency requires efficiency of % → co sequestration energy penalty of sequestration: efficiency reduction by about % co deposition + enhancement of oil recovery → cost reduction successful example: sleipner platform (norway) nuclear fusion fuels: lithium + deuterium from stones and water first fusion power plant in years → too late for present problems june decision: iter will be built in cadarache (france) further options ● pebble bed reactor ● transmutation ● combined heat and power production in homes ● hydropowered fuel cells: for cars? stationary fuel cells for small scale heat and power production (more promising) . challenges ● highest priority: reduction of greenhouse gases hard to achieve → example of germany ● limitation of temperature rise to < °c in one century only for cut down of co emissions worldwide by % , in industrialized countries by % until (ipcc) ● immediate action required, waiting for climatic damage raises cost by factor up to (stern report) ● decoupling of energy consumption from economic growth ● energy saving by raising efficiency streamlined energy usage → energy management substitution of energy sources and energy consuming devices sacrificing energy use wherever possible ● global dimension of energy shortage and environmental hazards → avoid wars! 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie 	folie energy, ecology and environment: a nexus perspective e d i t o r i a l energy, ecology and environment: a nexus perspective bin chen state key joint laboratory of environmental simulation and pollution control, school of environment, beijing normal university, beijing , people’s republic of china published online: february � joint center on global change and earth system science of the university of maryland and beijing normal university and springer-verlag berlin heidelberg the rising concern about a potential global energy crisis and its impact on the economy and environment calls for a transition from the current development paradigms to a sustainable one. such transition poses a significant chal- lenge for scientists, industries and governments requiring innovative policies to save energy and reduce environ- mental and social impacts considerably. moreover, the transition towards a low-carbon future needs to be cog- nizant of the social, cultural and institutional as well as the biophysical and geographical context within which it takes place and also in synergies provided by ecosystem services and technological regimes developing nature-inspired production and consumption systems. there is already plenty of literature on these problems, along with an abundance of journals with disciplinary territories and sharp boundaries on the intellectual landscape. however, we need a problem-oriented forum, transcending disci- plinary boundaries, for putting the pieces together for promoting informed discussions of an integrated vision of a sustainable world. the energy, ecology and environment (e ) issues, which are highly interwoven in the networks of human and natural systems, have been mostly disassembled into three separate aspects from a reductionist way of thinking, despite the trans-disciplinarity inherent in fundamental and applied research (dincer and rosen ; jørgensen and fath ; sciubba and zullo ; chen ; jørgensen et al. ). efforts in one discipline without considering wider links and consequences often prove to be invalid when promoting sustainability. for example, the increased use of energy may lead to potential environmental pollu- tion and ecosystem degradation. such trade-offs need linkage analyses and balanced solutions in an integrated way. also, since national, regional and local systems are deeply embedded in globalized networks, distributed pro- duction activities have become key drivers behind global change imposing stress on ecosystems across spatial scale due to spatial linkages between local activities and remote impacts (hubacek et al. ). different from the previous integrated thinking, nexus is a useful metaphor to investi- gate mutual dependency of multiple elements in terms of coupled mechanism being interlinked and conversion pro- cesses embedded in intertwined disciplinary chains at multiple scales. as shown in fig. , the e nexus, re- assembling both the interwoven connections and telecon- nections, is thus recommended as a new paradigm for tackling and resolving ‘‘wicked problems’’ (chen ; fig. nexus of energy, ecology and environment & bin chen chenb@bnu.edu.cn energ. ecol. environ. ( ) ( ): – doi . /s - - - http://crossmark.crossref.org/dialog/?doi= . /s - - - &amp;domain=pdf http://crossmark.crossref.org/dialog/?doi= . /s - - - &amp;domain=pdf chen and chen ). actually, the nexus approach has gained momentum over the past decade and is expected to uncover more information on the broadening issues of climate change, energy and food security, socio-economic growth and resource management and avoid unintended and indirect consequences (chen and lu ; costanza and kubiszewski ; yang and chen ). the list of problems that mankind is facing is very long, and all the problems are interrelated and cannot be solved separately and by one approach, but require an integrated approach based on the application of intra- and cross-dis- ciplinary solutions. no single discipline has the capacity to cope with these kinds of complex issues that require the implications of different aspects of the sustainable devel- opment of the world. a surge of interests has thus led us to integrate the main disciplines as our development strategy in order to adapt our future to the irreversible changes inherent in the human civilization. the newly launched journal, energy, ecology & environment (e ), focuses on approaches that integrate considerations of energy, ecology and environment and uses this cross-disciplinary integra- tion to be an important counterbalance towards the very dominating economic approach. despite the growing con- cern on e nexus, there are still many obstacles to devel- oping the tools and approaches at different scales. this journal may provide a cross-discipline forum to establish close links among these interrelated areas of investigation, set up systems science based on knowledge from other sciences and promote multidisciplinary solutions to tackle complex socio-economic and environmental problems. references chen b ( ) integration of energy, ecology and environment. front earth sci ( ): – chen b ( ) integrated ecological modeling for sustainable urban metabolism and management. ecol model : – chen b, chen sq ( ) urban metabolism and nexus. ecol inf : – chen b, lu y ( ) urban nexus: a new paradigm for urban studies. ecol model : – costanza r, kubiszewski i ( ) a nexus approach to urban and regional planning using the four capital model of ecological economics. in: position paper for united nations university, institute for integrated management of material fluxes and of resources (unu-flores) dincer i, rosen ma ( ) exergy-energy, environment, and sustainable development. elsevier, oxford hubacek k, feng k, minx j, pfister s, zhou nj ( ) telecon- necting consumption to environmental impacts at multiple spatial scales—research frontiers in environmental footprinting. j ind ecol ( ): – jørgensen se, fath b ( ) a new ecology—systems perspective. elsevier, oxford jørgensen se, marques jc, nielsen sn ( ) integrated environ- mental management: a transdisciplinary approach. crc press, boca raton sciubba e, zullo f ( ) is sustainability a thermodynamic concept? int j exergy ( ): – yang j, chen b ( ) energy-water nexus of wind power generation systems. appl energy : – b. chen 	energy, ecology and environment: a nexus perspective 	references . memo from president truman stating that israel’s government had been finally recog- nized, may , : [Електронний ресурс]. — Режим доступу : www.trumanlibrary.org/whis- tlestop/study_collections/israel/large/documents/newpdf/ .pdf#zoom= . public papers of the presidents of the united states: harry truman, – . — was- hington : u.s. g.p.o, – . . radosh r. a safe haven: harry s. truman and the founding of israel / a. radosh; r. radosh. — n. y. : harper, . — p. . spiegel s. the other arab-israeli conflict. making america’s middle east policy, from truman to reagan / spiegel s. — chicago : university of chicago press, . — p. . the consequences of the partition of palestine, ore , november , . central intelligence agency : [Електронний ресурс]. — Режим доступу : http://www.foia.cia.gov / sites/default/files/document_conversions/ /doc_ .pdf . the israel-arab reader: a documentary history of the middle east conflict / edited by walter laqueur; barry rubin. — n.y. : penguin books, . — p. . truman h. the memoirs by harry s. truman / truman h. — vol. , years of trial and hope: – . — n.y. : doubleday, . — p. А. Л. Хрипунова УДК: . ( ) ПЕРЕДУМОВИ РОЗВИТКУ НАЗЕМНОЇ ФОТОЕЛЕКТРИКИ у -Х рр. ХХ ст. У статті розглянуто історичні передумови, які призвели до світової енер- гетичної кризи у -х рр. ХХ ст. Ключові слова: екстенсивний розвиток економіки; деколонізація видо- бутку нафти; енергетична криза; фотоелектрика. В статье рассмотрены исторические предпосылки, которые привели к мировому энергетическому кризису в -х гг. ХХ в.: экстенсивное разви- тие экономики, деколонизация добычи нефти, отказ администрации США от золотого обеспечения американского доллара, эмбарго на постав- ку нефти. Ключевые слова: экстенсивное развитие экономики; деколонизация до- бычи нефти; энергетический кризис. the article researches the historical background that led to the global ener- gy crisis in years of the th ct.: extensive economic development, decoloniza- tion oil extraction, failure by the united states gold backing from the us dollar, the embargo on the oil supply. in the united states and european countries were initiated different projects to ensure energy independence. in the us in was funded by the nation’s largest program in the field of photovoltaics. the positive experience of the program has shown that using solar energy can solve energy problems. based on the positive experience of the united states in five years in germany begins a state program for the development of photovoltaics. the pres- ence of german industrial companies that produce solar cells based on monocrystalline silicon for space applications and scientific schools in the field of photovoltaics, allowed to develop evidence-based national programs. devel- opment of the photovoltaic contributed to the diversification of research that fo- cused not only on the development of structural and technological solutions of crystalline silicon solar cells, but also on optimization the technology of thin-film solar cells based on cadmium sulfide and amorphous silicon. keywords: extensive economic development; decolonization oil; the ener- gy crisis; photovoltaics. Загальновідомо, що суттєвою економічною проблемою України є об- меженість власних енергоресурсів. Останні події також показали, що ім- портна залежність у забезпеченні енергоносіями дає змогу політично тис- нути на нашу країну. Таким чином стратегічним завданням розвитку Ук- раїни є максимальне збільшення в її енергетичному балансі частки енер- гії, виробленої за рахунок власних енергетичних ресурсів. Тому форму- ється інноваційна структура енергетичного балансу України, яка перед- бачає використання нових джерел енергії. Перехід на них — найважли- віший етап у розвитку суспільства. Перший бурхливий перехід відбувся з по рр., коли каретно-кінну тягу було замінено на автомобілі, а газові світильники — на електричні. Слід зазначити, що це призвело до промислової революції в більшості розвинутих країн світу. Нині людство переживає етап переходу на відновлювані джерела енергії, який почався р. та за прогнозами вчених триватиме до р. Особливість цього етапу полягає в екологічній спрямованості. Внаслідок географічного по- ложення та кліматичних умов України, одним з перспективних видів від- новлюваних джерел енергії для нашої країни є сонячна. Отже, метою статті є визначити передумови швидкого розвитку назем- ної фотоелектрики в розвинутих країнах світу, що надзвичайно актуаль- но для визначення стратегії й тактики розвитку України. Для реалізації ме- ти слід визначити вплив економічних та політичних процесів у -х рр. ХХ ст. на розвиток наземної фотоелектрики, а також дослідити досвід ор- ганізації та реалізації перших наукових проектів у цій галузі. Індустріальний період часто називають періодом екстенсивного роз- витку економіки або добою дешевого палива. Протягом – рр. річ- не зростання світового споживання енергії в , раза перевищило темпи приросту населення планети [ , с. ]. Швидкий промисловий розвиток підтримувався низькими цінами на нафту, основний енергоносій у розви- нутих країнах світу. Проте на початку -х рр. ХХ ст. темпи споживання нафти почали випереджати темпи зростання її видобутку [ , с. ]. Це ство- рило об’єктивні передумови для подорожчання нафти і, як наслідок, ін- ших енергоносіїв. Підвищенню цін на енергоносії також сприяла також націоналізація нафтовидобутку в Алжирі та Іраку на початку -х рр. за підтримки СРСР [ , с. ]. Серед нафтових компаній Європи та США, які видобували нафту в районі Перської затоки, виникло цілком обґрун- товане побоювання, що націоналізація відбудеться і в інших країнах Близь- кого Сходу. Тому в жовтні р. дев’ять західних нафтових компаній да- ли згоду віддати % своїх акцій урядам цих країн [ , с. ]. Окрім цьо- го, компанії обіцяли підняти частку участі державного сектору в капіта- лах компаній до % р. р. середня виплата за видобуту нафту країнам-виробникам цього регіону збільшилася на % [ , с. ]. Однак це не зупинило деколонізації нафтовидобутку. Тому в березні р. іран- ський уряд посилив контроль держави над нафтовидобувною промисло- вістю. При цьому було гарантовано постачання нафти до США та євро- пейських країн майже в колишньому обсязі. р. до зростання ціни на енергоносії призвела одностороння від- мова адміністрації президента США Р. Ніксона від золотого забезпечення американського долара — основної резервної світової валюти [ , с. ]. Цей крок спричинив значні економічні втрати в усьому світі, а особливо в арабських країнах Перської затоки. У червні р. міжнародні нафто- ві компанії погодилися задовольнити вимоги шести арабських країн — чле- нів Організації виробників та експортерів нафти (ОПЕК) — Іраку, Лівії, Кувейту, Саудівської Аравії, Об’єднаних Арабських Еміратів і Катару — та компенсували втрати, завдані девальвацією долара [ , с. ]. Відпо- відно до підписаної в Женеві липня р. угоди, ці країни домоглися нового підвищення цін на свою нафту [ , с. ]. Окрім того, міжнарод- ні нафтовидобувні компанії гарантували, що враховуватимуть інтереси кра- їн-експортерів нафти у разі подальшого загострення валютної кризи. За- гальний приріст прибутків нафтовидобувних країн р. досяг млрд. доларів, у той час як р. він не перевищував млрд. доларів. Звернемося до подій, коли в -х рр. арабські країни почали вико- ристовувати нафту як важіль тиску на США та європейські країни, щоб домогтися зручного для них врегулювання конфлікту з Ізраїлем [ , с. ]. Ізраїльтяни пропонували прямі переговори між Ізраїлем та арабськими краї- нами, які мали сприяти мирному договору. Згодом було заплановано від- вести ізраїльські війська до визначених на переговорах кордонів. Єгипет і Йорданія пропонували свої етапи. Спочатку Ізраїль відводить війська до кордонів р. Після починаються переговори через представників ООН, результатом яких буде мирна угода. При цьому жоден з опонентів не по- годжувався на компроміси. Все це призвело до війни Судного дня, в якій проти Ізраїлю виступили Сирія та Єгипет, що отримали від СРСР вели- чезну кількість зброї. Підтримка СРСР була зумовлена глобальним зма- ганням з США, які підтримували Ізраїль. З по рр. Радянський Союз поставив до Єгипту й Сирії озброєння на – , млрд. доларів [ , с. ]. Уже в травні р., за півроку до війни, арабські країни опублікували рі- шення «включити нафтову війну в конфронтацію з Ізраїлем». Таким чи- ном, травня р. Ірак, Кувейт та Лівія тимчасово призупинили по- стачання нафти західним клієнтам. жовтня р. на нараді в Кувей- ті було ухвалено скоротити видобуток нафти в країнах ОПЕК на – %. Через кілька днів арабські нафтовидобувні країни оголосили, що повніс- тю припиняють постачати нафту до США та Голландії. Незабаром ембар- го було поширено на нафтопереробні заводи в Греції, Франції, Італії, Ка- наді, Тринідаді, на Багамських островах, у Сінгапурі та Бахрейні. Обме- жувальні заходи також призвели до зростання ціни на нафту. жовтня р. ціна за барель нафти протягом год. зросла з , долара до , долара [ , с. ]. Ще до підписання перемир’я листопада р. десять арабських країн — членів ОПЕК ухвалили скоротити видобуток нафти в грудні на %. Тому з січня р. ціна за барель нафти дійшла до , долара [ , с. ]. Через припинення поставок нафти Голландії довелося заборонити меш- канцям усі поїздки на приватних автомобілях у неділю. В цей час попит на велосипеди в Італії породив чорний ринок. Французька автомобільна промисловість була змушена на декілька днів зупинити виробництво. Уря- дам Європи довелося скоротити кількість рейсів на авіалініях, урізати час телепередач, обмежити швидкість на дорогах [ , с. ]. Відзначимо ко- ротко, що за період кризи в Німеччині промислове виробництво скоротилось на %, у Великій Британії — на %, у Франції — на %, в Італії — на %. Курси акцій тільки за рік, з грудня по грудень р., впали у Німеччині на %, у Великій Британії — на %, у Франції — на %, в Італії — на % [ , с. ]. Банкрутств р., порівняно з р., по- більшало в Німеччині на %, у Великій Британії — на %, у Франції — на % [ , с. ]. Нафтова криза ініціювала прогресивні структурні зміни в усій світо- вій економіці. Вона вдарила по традиційних енергоємних галузях промис- ловості та зробила ефективнішим вкладення коштів у розвиток нових, менш матеріало- та енергоємних [ , с. ]. У традиційних галузях економічна криза стимулювала впровадження енергозберігальних технологій у неба- чених до цього масштабах [ , с. ]. Уряди європейських країн почали запроваджувати жорстку програму заощадження електроенергії. Зверне- мося до події, коли у Франції інспектори робили раптові рейди по офісах, магазинах і виробництвах, щоб виміряти температуру приміщення. Якщо вона перевищувала встановлені °С, то на власників або орендаторів при- міщень накладали великі штрафи. Також було введено заборону на будь- яку рекламу, яка заохочувала споживання електроенергії [ , с. ]. Ще одним наслідком нафтової кризи -х рр. стало поступове зменшення імпорту рідкого палива за рахунок розвитку власного нафто- видобутку. Так, нафтові ресурси шельфу Північного моря здебільшого бу- ло розвідано ще до кризи, проте промислова їх експлуатація стала доціль- ною лише в нових економічних умовах. Цим уміло скористалися нафто- ві компанії Англії та Норвегії, які забезпечили своїм країнам енергетич- ну незалежність, завдяки промисловому видобутку нафти з шельфу Пів- нічного моря. В інших розвинених країнах Європи паливна криза викликала реструк- туризацію енергетичних балансів [ , с. ]. Так, у Данії та Голландії швид- ко розширювалося споживання природного газу, який видобувався на при- бережному шельфі [ ]. У виробництві електрики в цих країнах почала зрос- тати частка вітроенергетичних потужностей. Франція нарощувала зусил- ля в ядерній електроенергетиці, довівши майже до % її частку в енер- гобалансі країни [ , арк. – ]. Так Франція практично відмовилася від ви- користання мазуту у виробництві електрики за рахунок повернення до ви- користання власного вугілля та обмеження енерговикористання. Німеччи- на разом з енергозбереженням почала активно імпортувати російський газ з відкритих родовищ Західного Сибіру [ , с. ]. При цьому, враховую- чи можливість політичного шантажу з боку СРСР, стала європейським лі- дером у розробці та використанні відновлюваних джерел енергії, насам- перед сонячної. Звернемось до історичних подій, коли р. в «bell telephone com- pany research laboratories» у Нью-Джерсі (США) було розроблено крем- нієві елементи, в яких під дією сонця генерується електрична енергія. Со- нячні елементи спочатку застосовувались для електропостачання косміч- них апаратів [ , с. ]. р. було запущено перший супутник «van- guard» з енергетичною системою зі окремих сонячних елементів [ , с. ]. р. запущено супутник «explorer vi» з енергетичною системою потужністю Вт, яка включала сонячних елементів [ , с. ]. У цей час світова фотоелектрична індустрія складалася лише з кількох вузько - спеціалізованих компаній, які випускали сонячні елементи тільки для кос- мічного застосування. Критична ситуація з постачанням нафти позитивно вплинула на обіз- наність громадськості в нестабільності енергетичної ситуації. Тому в сус- пільстві з’явилася думка про те, що всі уряди розвинутих країн світу ма- ють ужити рішучих заходів щодо забезпечення енергопостачання. Щоб вирішити проблему енергозабезпечення, Міністерство енергети- ки США р. запросило групу експертів на легендарну конференцію «cherry hill» [ . с. ]. Ця конференція є відправним пунктом у розвит- ку наземної фотоелектрики. Під час неї експерти висловили думку, що са- ме фотоелектрична генерація може відігравати суттєву роль у забезпечен- ні США електроенергією. Як наслідок, уряди США, а потім — розвину- тих країн Європи прийняли закони, спрямовані на підтримку широкомас- штабного наземного впровадження фотоенергетики. Окрім того, р. у США та р. в Німеччині та Японії було запроваджено безпрецедент - ні за обсягами фінансування програми досліджень і розвитку (r&d) фо- тоелектрики. Таким чином, у США з р. протягом років було ви- ділено , млрд. доларів [ , с. ]. Піком фінансування проекту був р. Такий обсяг коштів перевершено тільки через років. Термін реалізації цих програм відповідає першому етапу розвитку наземної фотоелектри- ки. Це був час ейфорійної піонерської фази, яка підтримувалася величез- ним бюджетним фінансуванням наукових досліджень та економічними за- охоченнями промисловості для створення національної фотоелектричної системи. В реалізації програм брало участь лише кілька великих компа- ній. Цей період характеризувався нереальними очікуваннями швидкого ство- рення сонячних елементів, що виробляють електроенергію, конкурентос- проможну порівняно з традиційними джерелами енергії. Тонкоплівкова тех- нологія виробництва сонячних елементів, при реалізації якої кристаліч- ний кремній замінювався на дешеві плівки сульфіду кадмію та міді або аморфного кремнію, вважалась найперспективнішим шляхом розвитку на- земної фотоенергетики. Затягування на чотири роки початку фінансуван- ня фотоенергетики в Німеччині, порівняно зі США, пов’язано з тим, що в німецьку програму енергетичних досліджень у – рр. відновлю- вані джерела енергії включено не було. Основна увага приділялася ядер- ним реакторам високої температури, зріджуванню вугілля та ядерному син- тезу. Відповідно до програми, енергетичний баланс Німеччини р. мав містити % ядерного палива, % вугілля, % нафти і % природного газу [ , арк. ]. Проте до програми «Перша програма енергетичних до- сліджень та енергетичних технологій – рр.» було включено роз- робку відновлюваних джерел енергії, які тоді називалися неядерними енер- гетичними джерелами [ , с. ]. Розвитку фотоелектрики було присвя- чено «Програму технологій для використання сонячної енергії у – рр.», яку розробило Німецьке федеральне міністерство дослід- жень та технологій [ , арк. – ]. У -х рр. німецькі компанії «aeg-telefunken», «azur» та «intel- sat » почали виробляти кремнієві сонячні елементи для космічного засто- сування. З середини -х рр. ХХ ст. ці компанії виробили перші наземні сонячні елементи. В той самий час відома німецька фірма «wacker», яка виробляла напівпровідниковий кремній для мікроелектроніки, спрямува- ла зусилля технологів на розробку недорогого кремнію, придатного для застосування в сонячних елементах. Так було розроблено інноваційну крис- талізацію полікристалічного кремнію для наземних сонячних елементів. Ця технологія обходилась набагато дешевше за традиційне вирощування монокристалічного кремнію шляхом витягування монокристалів з розпла- ву. Отримані кремнієві пластини успішно використала фірма «aeg-tele- funken» для створення ефективних наземних сонячних елементів. Це бу- ло революційним кроком у розвитку фотоелектрики для наземного вико- ристання. Нині такі кремнієві сонячні елементи займають найбільший сег- мент світового ринку фотоелектрики. Таким чином, усі наукові проекти, що стосувалися виробництва кремнію для наземного застосування, фір- ма «wacker» передала дочірній компанії «heliotronic gmbh», яка вирощу- вала полікристалічний кремній та виробляла з нього пластини — основу сонячних елементів. Такий полікристалічний кремній став широковідо- мий під маркою «silso». Компанії «aeg-telefunken» та «wacker» роз- робили восьмирічну програму, яку фінансувало Німецьке федеральне мі- ністерство досліджень та технології. Ця програма розпочалася р. [ , с. ]. Трохи пізніше фірма «siemens» також розпочала велику наукову програму, яка містила весь технологічний цикл створення кремнієвих со- нячних елементів: від підготовки чистого кремнію до створення сонячних модулів [ , с. ]. В цей період починаються наукові проекти плівкових сонячних елемен- тів, які, за рахунок матеріало- та енергоощадних технологій виготовлен- ня, вважаються найперспективнішими для наземного застосування. Пер- ша програма «nukem» мала провести трансфер лабораторної технології тонкоплівкових сонячних елементів на основі cu s/cds, розробленої в Штутгартському університеті під керівництвом проф. В. Блосса, у промис- лову технологію. Однак у ході роботи було виявлено наявність деграда- ційних структурних процесів в означених сонячних елементах. Таким чи- ном, р. розвиток тонкоплівкової фотоелектрики зупинився. Програ- му «nukem» було зосереджено на комерціалізації сонячних елементів на основі структур метал-діелектрик-напівпровідник з інвертованим гетеро- переходом, конструкцію яких розробили в університеті Ерланген під ке- рівництвом проф. П. Хезеля [ , с. ]. р. в Німеччині під керівниц- твом проф. Г. Вінтерлінга розпочався дослідницький проект, метою яко- го було визначити промисловий потенціал плівкових сонячних елементів на основі аморфного кремнію [ , с. ]. Аналогічні проекти під керів- ництвом професорів С. Овшинського та Л. Козмерського реалізовувались у США [ , с. ]. Розвиток наземної фотоелектрики набирав обертів. Отже, можемо констатувати, що через екстенсивний розвиток еконо- міки темпи споживання нафти почали випереджати її видобуток. Деколо- нізація добування нафти дала арабським країнам змогу контролювати сві- тові ціни на цей ресурс. А використання нафти як зброї політичного шан- тажу призвело до запровадження ембарго на її постачання в США та єв- ропейські країни. Наслідком подорожчання нафти та ембарго на її поста- чання до Європи та США став розвиток матеріало- і енергозберігальних технологій та створення умов для забезпечення енергонезалежності цих країн. Позитивний досвід запроваджених у США національних програм з розвитку фотоелектрики показав перспективність цього напрямку від- новлюваних екологічно чистих джерел енергії. Внаслідок цього в Німеч- чині також було започатковано величезні за обсягами фінансування дер- жавні програми для підтримки розвитку фотоелектрики. Наявність про- мислових німецьких фірм, які виробляли сонячні елементи на основі мо- нокристалічного кремнію для космічного застосування, та наукових шкіл у фотоелектриці дала змогу розробити науково обґрунтовані національ- ні програми з наземної фотоенергетики, що мали прикладну спрямованість. Практичній спрямованості досліджень сприяла розробка технології при- датного для використання в сонячних елементах полікристалічного крем- нію, що суттєво зменшувало собівартість виробленої електричної енергії. Розвитку фотоенергетики сприяла диверсифікація наукових досліджень, спрямованих не тільки на розробку конструктивно-технологічних рішень кристалічних кремнієвих сонячних елементів, а й на оптимізацію техно- логії виготовлення тонкоплівкових сонячних елементів на основі сульфі- ду кадмію та аморфного кремнію, які принципово давали можливість ви- робляти електроенергію, конкурентоспроможну порівняно з традиційни- ми джерелами енергії. Міжнародні договори та високий рівень економіки не можуть захис- тити країни від економічного та політичного шантажу з боку експортерів енергоносіїв. Тому забезпечення власними енергоносіями є не тільки еко- номічним, а й політичним завданням незалежної країни. Досвід розвину- тих держав світу переконливо показує, що за умови широкої фінансової державної підтримки однією зі складових у вирішенні енергетичних та еко- логічних проблем є використання сонячної енергії. При цьому успішно- му розвитку наземної фотоенергетики сприяють наявність промислових підприємств електронного профілю, високий рівень наукових шкіл фото - електрики та диверсифікація напрямів наукових досліджень. . Бард М. Мифы и факты. Путеводитель по арабо-израильскому конфликту / Бард М. — М. : Еврейское слово, . — с. . Енергоефективність та відновлювані джерела енергії / Під заг. ред. А. К. Шидловського. — К. : Українські енциклопедичні знання, . — с. . Лаффин Д. Израильская армия в конфликтах на Ближнем Востоке – / Лаффин Д. — М. : Астрель, . — С. . . Максимов В. А. Исследование рынков основных энергоносителей / Максимов В. А. — Уфа : Издание Башкирского университета, . — с. . Максимов В. А. Эволюция мировой экономики и нефтяной рынок / Максимов В. 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Б. — Л. : Химия, . — с. . annual reports for the programme energy research and technology (in german on- ly): jahresberichte zum programm energieforschung und energietechnologie, herausgegeben vom projektträger beo, fz jülich. . chapin d. a new silicon p-n junction photocell for converting solar radiation into elec- trical power / d. chapin, С. fuller and g. pearson // journal of applied physics. — . — vol. . — p. – . . coetzberger a. photovoltaic materials, history, status and outlook / a. coetzberger, С. heb- ling, h.-w. shock // materials science and engineering: r: reports. — . — vol. . — № . — p. – . david f. how we got here: the ’ s / david f. — new york : basic books, . — p. . german status reports pv r&d (in german only): statusreports photovoltaik und , herausgegeben vom projektträger beo, fz julich. . german research plans energy research (in german only): forschungsplan energie- forschung und energietechnologien ( ) und ( ) des bmft bzw bmbf. . inglehart r. modernization and postmodernization: cultural, economic and political change in society / inglehart r. — prinston : prinston university press, . — p. . key world energy statistics. — paris : international energy agency, . — р. . krieder j. f. solar energy handbook. photovoltaic solar energy conversion systems, history / j. f. krieder, e. i. chief. — chapter . — p. – . . loferski j. j. the first forty years: a brief history of the modern photovoltaic age / j. j. lo- ferski // progress in photovoltaic. — . — vol. . — № . — p. – . . perlin j. from space to earth : the story of solar electricity / perlin j. — cambrid- ge : first harvard university press edition, . — p. . rauber a. strategies in photovoltaic research and development — r&d and history / a. rauber // photovoltaics. guidebook for decision makers / a. bubenzer, j. luther (eds.). — berlin : springer verlag. — . — p. – . . staiß f. strategies in photovoltaic research and development — market introduction programs // f. staiß , a. rauber // photovoltaics guidebook for decision makers / a. bubenzer, j. luther (eds.). — berlin : springer verlag. — . — p. – . . yergin d. the prize: the epic quest for oil, money, and power / yergin d. — usa : simon & schuster, . — p. О. В. Махно УДК: ( ) ДО ПИТАННЯ ПРО ОСОБЛИВОСТІ РАДЯНСЬКОЇ ІНФОРМАЦІЙНОЇ ПОЛІТИКИ ЩОДО АВАРІЇ НА ЧОРНОБИЛЬСЬКІЙ АЕС р. У статті проаналізовано специфіку радянської інформаційної політи- ки р. стосовно аварії на Чорнобильській АЕС. Ключові слова: СРСР; УРСР; Чорнобильська катастрофа; радянська ін- формаційна політика. В статье проанализирована специфика советской информационной по- литики относительно аварии на Чернобыльской АЭС, которая проводилась на протяжении всего г. Обоснован вывод о том, что эта политика определялась, с одной стороны, замалчиванием сведений об аварии, а с дру- гой — активизацией контрпропагандистских мероприятий, направленных на обвинение «капиталистического мира» в распространении неправдивой и политически заангажированной информации. Ключевые слова: СССР; УССР; Чернобыльская катастрофа; советская информационная политика. this article is devoted to the specific of soviet informative politics in relation to an accident on chornobyl nuclear power plant that was conducted during . a conclusion that this politics was determined, from one side, by suppressing of information about an accident, and, from other side, by activation of the coun- terpropaganda events sent to accusing of the «capitalist world» of distribution of untruthful and politically accented information is well-proven. keywords: the ussr; ukrainian ssr; chornobyl catastrophe; soviet infor- mative politics. oil-column calculations in stratigraphic traps: abstract; geothermal power in the southwest: abstract; recent and ancient turbidites and contourites: abstract association round table slope in the alaminos canyon area, gulf of mexico, indicate sand input from the ancestral colorado-brazos and mississippi river systems. the clay minerals in the area were derived from indeterminate sources and were incorporated in coarse samples through resuspension of former sediment. vermiculite, as well as tubular hallaysite, were identified in clay samples. the first mineral is unreported in the northwest gulf and the latter is only known from the mississippi delta in the northwest gulf area. the "hummocky" nature of the bathymetry in the area re- sulted from salt diapirism and scouring by tractive and/or density flow. sand-size sediment was transported to the area from river systems by longshore drift during the holocene transgression or through channels still identifiable on the pres- ent continental shelf the lineation of one of these features, the outer colorado-brazos channel, is probably due to salt tecton- ics and not the result of a barrier spit as previously reported. berg, r. r., dept. geology, texas a&m univ., college station, tex. oil-column calculations in stratigraphic traps oil columns can be calculated for simple stratigraphic traps if the rock and fluid properties are known or can be estimated. because oil migration is prevented by capillary pressure in small pores of the trap fades, direct measurements of capillary pressure allow oil columns to be calculated, but such measure- ments are rare. an alternative is to determine pore size from porosity and permeability data using an empirical equation, and then to compute the capillary pressure by an estimate of fluid properties. an example of oil-column calculation is from the milbur field, burleson county, texas, a lower wilcox stratigraphic trap. using core analysis from a nearby well, an oil column of - ft would be expected for the trap, and this estimate agrees reasonably well with an actual oil column of - ft for the field. the most important part of such calculations is the real- ization that the trapping facies itself can have significant poros- ity and permeability and yet form an effective barrier to oil migration. the result is that the best reservoir may occur down- dip from dry holes with porous water-bearing sandstone and oil shows, rather than updip at the pinchout. birdseye, h. s., consultant, albuquerque, n.m. geothermal power in the southwest in this era of great concern over the environment and the energy crisis, much attention is being directed toward geother- mal power as a partial panacea for both predicaments. of approximately , known geothermal occurrences in the uaited states, most of which are in and west of the rockies, a relatively small percentage are classified as dry steam reservoirs, capable of producing hot unsaturated steam which poses mini- mal efiluent disposal problems. others, such as the salton sea field in southern california, pose critical waste brine difficulties, which will probably be solved only by reinjection. a major geothermal field, e.g., the geysers in northern california, is expected to produce steam adequate to generate from , to , megawatts of electricity, with -year gross revenue from steam sales on the order of $ billion. there are known geothermal occurrences in the southwestern states of texas (less than a dozen). new mexico ( ), arizona ( ), nevada ( ), and southern california (about ). it is likely that additional geothermal prospects will be developed by the use of sophisticated geologic mapping, coupled with such geophysical methods as studies of temperature-gradients, mi- croseisnris and ground noises, resistivity, and remote sensing, and chemical methodology useful in determining maximum water temperature in the system and the age of that water. bouma, a. h., dept. oceanography, texas a&m university, college station, tex. recent and ancient turbidites and contourites fossil turbidites have been recognized and described from many areas all over the world. a turbidite model, comprised of a fixed succession of sedimentary structures, was established a decade ago and seems to be usable, although some changes have been suggested. turbidites are generally assumed to be deposited by turbidity currents, but the presence of these currents in the marine realm has not been definitely established. submarine canyons presum- ably are the major, if not only, important transport route for moving "shallow" water material to "deeper" basins. questions arise about the origin of turbidity currents when studying can- yons in which gradual filling followed by sudden emptying has occurred. the material in the canyon head moves downward slowly, comparable to glaciers. besides this slow sliding, trac- tion currents and debris flow have been suggested. where tur- bidity currents start, and if they absorb the slow moving can- yon fill, are questions that cannot be answered yet. other prob- lems are the relation between fluxoturbidites, or gravities, and turbidites, and the use of the terms "proximal" and "distal" turbidites. in comparing recent turbidites with ancient ones, many dis- crepancies appear, most of which can be euminated by consid- ering the influence of primary consolidation on segmentary structures. studies indicate that the use of electrical logging and seismic records do not allow detailed interpretation of deposits such as turbidites. the resolution of the records is not fine enough, although their application for basin analyses and overall trends is necessary. recently a new genetic term, "contourites," was introduced for sediments redeposited by contour currents. recent and ancient contourites are compared with turbidites and only mi- nor differences exist. a combination of parameters may allow a distinction between the two types and it is possible that both can be found in the same area. brown, l. f., jr., bur. econ. geology, univ. texas at aus- tin, austin, tex. south texas eolian system—model of coastal eolian processes few oil and gas reservoirs have been interpreted as sands deposited within eolian depositional systems. eolian facies may, however, be more common in ancient basins than heretofore recognized. continued documentation of holocene eolian sys- tems, such as the south texas system, provides a model for reevaluating the genesis of numerous unfossihferous, well- sorted blanket sand bodies, many of which are associated with ancient, paralic depositional systems. pleistocene paralic depositional systems along the south texas coast dictate the natiu'e and distribution of facies pat- terns, environments, and processes exhibited by the overlying holocene south texas eolian system. a dominant southeast wind, high summer temperatures, and high rainfall deficiency combine with an abundant supply of pleistocene sand to pro- vide the proper framework widiin which extensive eolian defla- tion and dune migration can occur. eolian lobes are supplied with sand from pleistocene barrier- strandplain facies and fluvial meanderbelt deposits. loess sheets are derived from distant lobes, as well as from deflation of local pleistocene deltaic and fluvial facies. deflation of thick pleistocene fluvial-deltaic sand facies is commonly stabilized when erosion reaches the shallow groundwater table. maximum deflation occurs on the upwind, coastward margin of the sys- tem, especially where only thin pleistocene paralic sands are available to supply dune trains; mud deflated by strong off- pii: - ( ) - volume , number febs letters april bioenergetics of tomorrow introduction to round-table discussion on bioenergetics of tomorrow e. c. slater laboratory of biochemistry, b. c. p. jansen institute, university of amsterdam plantage muidergracht , amsterdam, the netherlands shortly after the appearance of the second announcement of the febs meeting, i received a letter pointing out that a method introduced by the writer of the letter would play a big r le in future research in bioenergetics and that it would be very appropriate to include it in a round table discussion on bioenergetics of tomorrow. i am sure that he is right, and his letter made me realize that the title that we had given to this round-table discussion was at least misleading, if not pretentious. for this, i apologize. i hope, in any case, that since the publication of the list of speakers everyone now understands the purpose of this discussion, and that the chance of misleading bioenergetics can no longer be levelled at the organizers, even if the other reproach can still be made. the intention was, in any case, to discuss the r le that bioenergeticists can play and i believe must play in solving the energy crisis. this is not the greatest problem facing us. that is the population growth, and unless we can solve that one we are headed for disaster anyhow. however, even if we do succeed in stabilizing the population at a level not too much larger than the thousand millions that at present inhabit the earth, we shall still have to find enough energy for them to survive more than a few hundred years or so. since virtually all the energy that we use is derived from the sun by a bioenergetic conversion it is not too pretentious for the bioenergeticist to claim that he has something to say about the problem. its magnitude is clearly expressed in the following figures. to stay alive the average man (including babies and children in the average) needs about kcal per day in the form of food. this is equivalent to about j per second, that is a continuous input of about w or the same as a fairly large electric light. this amount of energy is sufficient to make about . mmol atp per second. considering what man can do, w energy expenditure does not seem much. he is, in fact, a very efficient machine. however, since there are . x lo of us, the world population already needs the continuous production of . x ” w in the form of food. this energy is derived from solar radiation which has been absorbed by the chlorophyll in the chloroplasts and used to synthesize carbohydrates and other food- stuffs from carbon dioxide, water and nitrogen. we eat these plants or animals that have eaten plants. the agricultural production in the world is just about sufficient to supply this . x ” w continuous energy, and it could be geared to produce a little more, but not very much. it is painfully obvious that it will not be able to support the exponentially growing population much longer. this amount of w is, however, only sufficient to keep a naked man alive and reproducing. he needs a lot more energy to be clothed, stay warm in winter or cool in summer, live in houses, enjoy himself and to travel other than by foot. the total energy con- sumption over the whole world is about times as much, in prosperous countries like the united states times. it may seem paradoxical that man is reaching the limits of the possibilities of growing sufficient food, but at the same time is consuming times ( times in advanced countries) as much energy for non-vital purposes. this is especially so when we consider that the non-food energy that he is consuming was also laid down as a result of the ability of chlorophyll- containing energy-transducing membranes to convert solar energy into combustible fuel. the coal, oil and natural gas that we now burn is derived from the carbohydrate of forests growing millions of years ago. volume , number febs letters april cumulative energy consumption, based on % annual actress .:.. ::;..‘..,. z’.., .i.:: ‘.‘>..,., ., . / :;;,,: ..: .:. . . . . . . . . . . . ‘. . . . . . . . . ,.,_ ”ale o,l ::i”::‘:‘..: :i.>; .:...:.i. fig. . cumulative energy consumption, based on the estimated present consumption and a % annual increase, expressed as a percentage of the estimated reserve of fossil sun energy present on the earth. the cross-hatched and stippled areas indicate the percentage of these reserves in the form of oil and natural gas, and shale oil, respectively. the remainder is coal. this fossil sun energy is our energy capital and we are using it up now at a rate times faster than our solar-energy income derived from our present agri- culture. our total reserves of fossil sun energy are about times our present yearly use. this seems, at first sight, a reassuringly large amount. however, the simple graph in fig. shows that it is alarmingly small. in the first place, only % of these reserves are in the form of oil and natural gas, another % is in the form of shale oil and the remaining % in the form of coal, much of it difficult to mine. secondly, the world consumption of energy is (or was until very recently) increasing at the rate of about % per year, and it is difficult to see how this can be reduced much in the next decades, given the increase in the world popula- tion and the desire for increasing living standards among the poorer populations. even a relatively small annual accretion of % has frightening effects over quite a short period, measured by the lifetime of man. unless we do something about it, already by , reserves equivalent to all our oil and gas,would be gone, the reserves of shale oil would follow a few years later and in years, within the lifetime of some of our grandchildren, everything would be gone. of course, we must do something about it. the first requirement, if an enormous catastrophe is to be prevented, is to stop the population increase. if we cannot do this, we are finished anyway. even if we are successful, however, we have to find new forms of energy and, if we would like man to continue to enjoy this planet for a few hundred years more, new sources of energy income will have to be sought. in the short term, we might use up some other energy capital to give us time to work out ways of increasing our energy income. theoretically, geothermic energy, revealed to us in hot springs and volcanos, might be used. it has been estimated that these stores amount to about % of the fossil sun energy (see fig. ). however, we do not know yet how x ~ p a x c earth’s energy reserves fig. . an estimate of the earth’s energy reserves. two calcula- tions have been made of the reserves of fissionable material (uranium and thorium), both on the assumption that it is economically and politically feasible to build breeding reactors. the higher estimate makes the additional assumption that it will also be possible to extract uranium from the sea, the lower (shown by the dotted line) that it will not. volume , number febs letters april to tap this source. we do know how to use the energy made available by splitting heavy atoms, and, despite the political dangers, it seems inevitable that we must introduce nuclear reactors on a large scale. however, the amount of thorium and uranium is limited and, with the reactors now in use, only sufficient to supply the world with energy at the rate for about years, unless uranium can be obtained from the sea. this becomes financially feasible only if the energy yield of the reactors is increased, by the use of breeding reactors. in that case, the total reserves of uranium and thorium are equivalent to about times our fossil sun energy. if it is not possible to extract uranium from the sea, it is only one fifth the amount of fossil sun energy. theoretically, it is possible to obtain energy by the fusion of light atoms, e.g. deuterium with tritium. however, tritium has to be made from lithium, and this is also present in restricted amounts, sufficient to yield energy equivalent to about % of our fossil sun reserves. the fusion of deuterium and deuterium would give virtually unlimited reserves of energy and if the physicists ever succeed in this they will have made a sun on earth, and the energy crisis will be over. in case they do not, however, and until they do, we have to make use of the sun we have. this is our energy income. (it is true that we can harness the wind and the tides, but these can at best make a very small contribution to our total needs.) the earth receives . x lo’? w radiant energy from the sun, times our present total consumption. and it sends out this energy whether we use it or not, so we are not robbing future generations by using it now. we can harness directly the heat of the sun, not only for heating houses, but also to drive electrical turbines or to split water into hydrogen and oxygen. but this is rather costly and the bioenergeticist would like to copy the way nature does it. it is indeed perfectly feasible to allow a chloroplast suspension to reduce a low-potential dyestuff with reducing equivalents derived from the photolysis of water (the oxidizing equivalents are evolved as oxygen) and to feed these reducing equivalents to hydrogenase which converts them to molecular hydrogen. the system chloroplasts t dyestuff + hydrogenase can bring about the photolysis of water to hydrogen and oxygen. hydrogen is, in many ways, the ideal fuel since the product of its combustion is water. more research on the efficiency of the energy conversion and on means to stabilize the catalysts, either extracted from living material or made in the chemical factory, is required before the technological feasibility, in particular the cost, can be assessed. the first three speakers this afternoon will direct themselves to this aspect. the next two will deal with the observation that, in sunlight, certain bacteria (growing normally where the concentration of salt is high) can produce an electrical potential across the cell membrane. this also deserves exploration as a possible method of utilizing solar energy. i hope that the speakers, and those contributing to the general discussion, will give attention to the gaps in our knowledge of bioenergetics that will have to be filled before the bioenergeticist can talk to the engineer, so that these theoretical possibilities can be tested in practice. man does not have much choice. either we trust the physicist to make us a sun without blowing us up, or we let the bioenergeticists use our present one. otherwise, we won’t last more than a hundred years or so. this is an exciting challenge for the bioenergetics of tomorrow. modified tio photocatalyst for co photocatalytic reduction_ an overview contents lists available at sciencedirect journal of co utilization journal homepage: www.elsevier.com/locate/jcou review article modified tio photocatalyst for co photocatalytic reduction: an overview hamidah abdullaha,b, md. maksudur rahman khanb, huei ruey ongb, zahira yaakoba,⁎ a department of chemical and process engineering, faculty of engineering and built environment, universiti kebangsaan malaysia, bangi, selangor, , malaysia b faculty of chemical and natural resources engineering, universiti malaysia pahang, gambang, kuantan, pahang, , malaysia a r t i c l e i n f o keywords: carbon dioxide (co ) photocatalyst titanium dioxide (tio ) a b s t r a c t the photocatalytic pathway to reduce carbon dioxide (co ) to fuel, an artificial photosynthesis process, is a futuristic and ultimate way to combat the energy crisis and co emission issues. the most widely used catalyst for photocatalytic reactions is titanium dioxide (tio ) due to its availability, chemical stability, low cost and resistant to corrosion. although tio photocatalyst suffers due to its wide band gap (only can be activated under ultraviolet light irradiation) and high electron-hole recombination rate, it remained as a precursor for the de- velopment of visible light responsive materials for co reduction through different modifications, such as doping of metal, nonmetal, semiconductors etc. there is a significant improvement in co conversion using the visible light responsive tio based catalysts. the product distribution due to the photocatalytic reduction of co highly depends on the band gap and band edges of the catalyst. the understanding in the mechanistic pathway of co reduction is very important to design the catalyst for the production of desired product. this present paper provides an overview of research and development of tio based photo-catalysts for co reduction and focuses on the improvement of the photocatalyst based on the band gap engineering, charge transfer and co adsorp- tion. moreover, the challenges and future prospect in the developing modified tio for photocatalytic reduction of co has also been discussed. . introduction photocatalysis can be defined as the acceleration of a photo-reaction by the presence of a catalyst [ ]. the catalyst in photo-reaction is able to absorb a photon from light and generate electron-hole pairs. this photo-generated electron and hole at the conduction band (cb) and at the valence band (vb) of the catalyst are used for reduction and oxi- dation reaction, respectively. photocatalytic reactions are widely used in water splitting to produce hydrogen and oxygen [ ], dye degradation [ , ] and co reduction [ , ]. the most widely used photocatalyst for the photocatalytic reactions is titanium dioxide (tio ) due to its availability, chemical stability, low cost and resistance to corrosion [ ]. however, using tio comes with its own limitations. it is only active when irradiated by uv light, due to its wide band, which makes it not as effective under sunlight, since the solar spectrum only consists of about % of uv light. adding to that, tio has a high electron/hole pair re- combination rate compared to the rate of chemical interaction with the adsorbed species for redox reactions [ ]. all of these traits, makes the development of a visible light driven photocatalyst with a lower re- combination rate of photo-generated electron-hole pairs highly desir- able. when it comes to the development of tio catalyst, a lot of sig- nificant studies has been made. various techniques have been employed to make the catalyst be able to absorb a photon when in visible light region and have a low electron-hole recombination rate. to name a few, all of the following techniques, such as doping [ ], non-metals doping [ ], coupling with others semiconductor [ , ], co-doping [ , ] and surface modification via organic materials [ , ] have been at- tempted. water splitting [ ], dye degradation [ ] and co reduction [ ] have been reported to benefit from using modified tio photo- catalyst compared to tio due to its higher photocatalytic activity. and since the reduction of co to hydrocarbon has great potential of pro- viding the world with an alternative fuel and solve our woes in regards to co emission, which incidentally, is one of the principal culprits in causing global warming, methods for photocatalytic reductions of said co merits more attention. however, the modifications to the tio photocatalyst that makes it successfull in water splitting and dye de- gradations under visible light irradiation fails to achieve the same success in co reduction. this is mostly due to the catalyst require- ments, in terms of cb and vb edge, being vastly different for co re- duction than for water splitting or dye degradation. the position of cb and the vb of the semiconductor can be a tool in determining the re- duction and oxidation capabilities of the photoelectrons. the photo- generated electrons and holes are efficiently utilized if the reduction potential and oxidation potential of the reaction is less negative and less http://dx.doi.org/ . /j.jcou. . . received march ; received in revised form july ; accepted august ⁎ corresponding author. e-mail address: zahirayaakob @gmail.com (z. yaakob). journal of co₂ utilization ( ) – - / © elsevier ltd. all rights reserved. mark http://www.sciencedirect.com/science/journal/ http://www.elsevier.com/locate/jcou http://dx.doi.org/ . /j.jcou. . . http://dx.doi.org/ . /j.jcou. . . mailto:zahirayaakob @gmail.com http://dx.doi.org/ . /j.jcou. . . http://crossmark.crossref.org/dialog/?doi= . /j.jcou. . . &domain=pdf 	modified tio photocatalyst for co photocatalytic reduction: an overview 	introduction 	reaction involved in photocatalytic reduction of co 	tio catalyst for photocatalytic reduction of co 	modified tio catalyst for photocatalytic reduction of co 	effect of dopants on band gap modification 	cation doped-tio 	anion doped-tio 	anion-anion doped-tio 	effect of dopant on charge carrier mobility 	cation doped-tio 	anion doped-tio 	cation-cation doped-tio 	effect of cation-anion co-doping on tio 	effect of other semiconductor on tio 	enhancement of co adsorption by surface modification 	photocatalytic reduction of co by modified tio 	mechanism of co photoreduction 	conclusions, challenges and future prospects in developing modified tio photocatalyst for photocatalytic reduction of co 	acknowledgements 	references stan cox: the green new deal and beyond: ending the climate emergency while we still can vol.:( ) agriculture and human values ( ) : – https://doi.org/ . /s - - - stan cox: the green new deal and beyond: ending the climate emergency while we still can jacob a. miller accepted: june / published online: june © springer nature b.v. stan cox’s the green new deal and beyond argues that the realities of our climate crisis require the elimination of fossil fuels from the u.s. economy and a realignment of the unjust system that allows for their exploitation. cox’s thesis is that the green new deal legislation (gnd) is a good first step, but we in the u.s. must also acknowledge and adhere to the limits of economic growth and material consumption. his evidence-driven analysis builds from the ipcc report’s finding that we need to achieve net-zero carbon emissions by if we are to limit global warming to .  °c. cox supports his argument in three major ways. first, he walks through the history of growth and limits from to the present, with special emphasis on – . second, he explains why limits are inescapable and how to achieve them through a plan called “cap-and-adapt.” finally, cox argues that any realignment must correct the social inequali- ties endured by lower- and middle- classes and the global south. initially, to ground the history of limits, cox discusses the new deal, resulting labor movement, and wwii rationing—examples where the federal government stepped in to stimulate the economy and impose limits. cox then reminds us of the book, the limits to growth, high- lighting its relevance for today. for instance, the books says “when we introduce technological developments that suc- cessfully lift some restraint to growth or avoid some col- lapse, the system simply grows to another limit, temporarily surpasses it, and falls back” (p. ) and “if you follow those ascending business-as-usual curves to which the world is still adhering out to the year , they show industrial and food production peaking out and then collapsing” (p. ). what was true fifty years ago is true today: technology must adhere to limits, entropy will always prevail, and industrial food production is unsustainable in the long run. cox goes on to explain the political pinball that ensued in response to the energy crisis of the s and s, including president carter’s attempt to decrease reliance on foreign oil and president reagan’s national energy plan and initiation of federal subsidies for fossil fuel expansion. as cox ventures into the s and s, he lays out major environmental and political milestones, and concludes each with the u.s. gross domestic product and co ppm emis- sions at that point in time (e.g. rio earth summit: $ . trillion (t),  ppm; kyoto protocol: $ .  t, u.n. green new deal: $ .  t,  ppm; paris agreement: $ .  t,  ppm). cox’s parallelism and juxta- position make the point that no matter the political or social milestone, a rise in gdp, buttressed by unrestrained energy and material consumption (sans unrealistic decoupling), directly correlates with a rise in global emissions. this historical overview leads cox into his second main point, that u.s. climate policies must work within limits. he begins by examining popular fixes—including carbon capture and storage, nuclear energy, and claims of per- cent renewables—and performing a reality check by citing leading research that counters these fixes. in many cases, we do not see their purported benefits because we gloss over key assumptions, such as the embodied energy and extrac- tion required by the steps leading up to the fix. for instance, consider electric car batteries, direct-air capture, and wind machines. simple calculations reveal the required energy that goes into growing, transporting, and processing cancels out a majority of gained benefits. cox’s demystification sup- ports his book’s hard-to-swallow maxim: we must adhere to ecological limits if we are to achieve net zero emissions by . achieving this begins with asking the right questions, cox asserts. not about what works best in economic models, or what is politically viable, but what ecology requires of us. once we ask that question we can go on an “energy diet” (p. * jacob a. miller tree @ksu.edu department of sociology, anthropology, and social work, kansas state university, waters hall, old claflin place, manhattan, ks  , usa http://orcid.org/ - - - http://crossmark.crossref.org/dialog/?doi= . /s - - - &domain=pdf j. a. miller ). similar to weight loss, there are no quick fixes besides healthy diet and exercise. cox provides individual actions we should take. these include eating local, eating less meat, and traveling and commuting less. less. as cox acknowl- edges, we have long known these will alleviate emissions, but most still avoid them because we “don’t want to think or talk about using less energy” (p. ). alongside individual change must come systemic change. after once again debunking unrealistic proposals, à la “eco- modernism” and “climate keynesianism,” cox introduces a “cap-and-adapt” proposal (p. ). called a policy “sugges- tion,” it would place annual, mandatory reductions on fossil fuels themselves, not just carbon or carbon equivalent emit- ted, thereby capping extraction. to enforce, the government would issue permits, and all imports and exports would be banned. for this suggestion to become policy, a “coxian” cohort would need to develop a more detailed framework, write the bill, model the legislation’s effects, and collect support statements from influential climate change leaders, economists, and politicians. as cox has written elsewhere, “cap-and-adapt” aims to turn the “green new deal” into the “new green deal” (ngd). the switch is not simply semantic. gnd relies on “malignant” “green growth” (cox ) that could promul- gate technological dependence (e.g. “slapping solar panels on top of walmart”) and allow the rich to profit from new “green” technologies. in contrast, ngd would ensure that any regulation put green first. here is where cox’s third point resides. any proposal must address the growing economic inequality, domesti- cally and abroad: “if we manage to achieve a fair, effec- tive climate-emergency policy, the percent of american households with highest incomes [> $ , annually] will most likely bear the greatest economic burden” (p. ). the poorest parts of the world in the global south are responsi- ble for only percent of global greenhouse emissions, yet they are subjected to climate change’s worst impacts. as evidenced by covid- and climate change, we live in a material world. cox reminds us that no frame, optimism, or flashy proposal will change that fact, and that no technol- ogy, market-based policy, or economic growth will save us from the burden of limits. driving each of cox’s paragraphs is a wide-eyed urgency, best summarized by the book’s sub- title. we do not have much time left to take the “off ramp” (p. ), and while most people ho-hum around, cox is busy laying out what it will take to ward off climate catastrophe, “while we still can.” reference cox, stan. . “that green growth at the heart of the green new deal? it’s malignant. counterpunch. of https ://www.count erpun ch.org/ / / /that-green -growt h-at-the-heart -of-the- green -new-deal-its-malig nant/. accessed may . publisher’s note springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. jacob a. miller is a research assistant for sociology, anthropology, and social work program at kansas state university. in the fall of , he enters the program as a ph.d. student. https://www.counterpunch.org/ / / /that-green-growth-at-the-heart-of-the-green-new-deal-its-malignant/ https://www.counterpunch.org/ / / /that-green-growth-at-the-heart-of-the-green-new-deal-its-malignant/ https://www.counterpunch.org/ / / /that-green-growth-at-the-heart-of-the-green-new-deal-its-malignant/ 	stan cox: the green new deal and beyond: ending the climate emergency while we still can 	references forecasting optimal solar energy supply in jiangsu province (china): a systematic approach using hybrid of weather and energy forecast models research article forecasting optimal solar energy supply in jiangsu province (china): a systematic approach using hybrid of weather and energy forecast models xiuli zhao, henry asante antwi, and ethel yiranbon school of management, jiangsu university, xuefu road, zhenjiang, jiangsu , china correspondence should be addressed to xiuli zhao; asanteantwi @gmail.com received october ; accepted november ; published january academic editors: r. pedicini and p. pei copyright © xiuli zhao et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. the idea of aggregating information is clearly recognizable in the daily lives of all entities whether as individuals or as a group, since time immemorial corporate organizations, governments, and individuals as economic agents aggregate information to formulate decisions. energy planning represents an investment-decision problem where information needs to be aggregated from credible sources to predict both demand and supply of energy. to do this there are varying methods ranging from the use of portfolio theory to managing risk and maximizing portfolio performance under a variety of unpredictable economic outcomes. the future demand for energy and need to use solar energy in order to avoid future energy crisis in jiangsu province in china require energy planners in the province to abandon their reliance on traditional, “least-cost,” and stand-alone technology cost estimates and instead evaluate conventional and renewable energy supply on the basis of a hybrid of optimization models in order to ensure effective and reliable supply. our task in this research is to propose measures towards addressing optimal solar energy forecasting by employing a systematic optimization approach based on a hybrid of weather and energy forecast models. after giving an overview of the sustainable energy issues in china, we have reviewed and classified the various models that existing studies have used to predict the influences of the weather influences and the output of solar energy production units. further, we evaluate the performance of an exemplary ensemble model which combines the forecast output of two popular statistical prediction methods using a dynamic weighting factor. . introduction china as a growing economy has high demand for electricity and nonrenewable sources of energy have been documented to have low capacity for supporting future social and eco- nomic development of china [ ]. there is high future demand for energy and a need to explore sustainable alternatives such as the use solar energy in order to avoid future chinese energy crisis. according to yang [ ] the conceptualization of renewable energy and its sustainability form the foundation of emerging agendas on the future sources and use of energy and energy planning in china as a whole. solar power, wind power, thermal power, hydropower, and nuclear power are categorized as renewable energy. from sustainability perspective, different sources of power have different life cycle costs, which further contribute to the differences in prioritization of the different renewable power sources [ ], although life cycle costs of nuclear power may be lower compared to life cycle costs of solar power and wind power, for example, nuclear plants are exposed to risks of nuclear and radiation emissions that have negative long term impacts on the plants and animals. solar power has advantage of lower maintenance costs over a long period of time [ ]. in china, the alignment of sustainability goals and contri- bution to socioeconomic development recognize solar power to have the lowest forms of environmental pollution and the lowest level of carbon footprint. for this reason solar power is perceived to be more competitive in china and more research and development have been targeted at improving innovation of solar power in china (at least with the last half of the century) [ ]. apart from its superiority in environmental sustainability goals, solar energy has a higher capacity to hindawi publishing corporation e scientific world journal volume , article id , pages http://dx.doi.org/ . / / http://dx.doi.org/ . / / the scientific world journal satisfy different industrial and domestic needs based on per- formance measures for achieving energy efficiency, energy saving capabilities, and capacity for reduction of emission technologies. in addition, solar power has higher advantages as a clean energy technology. as huang et al. [ ] have noted planning for energy use within a region or province is a huge investment-decision problem. currently most of the research works in solar energy issues in china are devoted to issues of demand and investments. usually demand issues are analyzed by investors using portfolio theory in order to manage risk and maximize portfolio performance under a variety of unpredictable economic outcomes. there is also a modicum of studies in china which encourages those responsible for energy policy formulation and planning to do away with the continuous reliance on traditional, “least-cost” stand-alone technology cost estimates. instead they should evaluate conventional and renewable energy sources based on the portfolio cost, the cost/risk versus contribution [ ]. while the demand for solar energy appears to be relatively high, its supply is not for several reasons in china. apart from variations, there is also a challenge in the sense that solar energy supply is given attention only in a few provinces in china compared to other forms of energy. for this reason there is the need to develop efficient and dedicated methods of forecasting solar energy as a basis for supporting energy planners and grid operators to efficiently and effectively manage the balance of power between demand and supply of solar energy to overcome any possible instability in and even possible collapses of the sector in the not too distant future [ ]. in respect of effective forecasting of solar energy supply, a number of studies exist in the extant literature both at indi- vidual and community levels to help cope with the situation. even though there is a large deposit of studies which interrogates both practical and scientific optimization ideas, it is still to be determined a straightforward and easy-to-use approach to standardized energy forecasting especially when it comes to solar energy. if the results of different experi- mental projects are compared, this makes it more difficult to arrive at a simplified and standardized energy forecasting approach because most of these studies analyzed cases that are region specific. further, there is no constant form of result evaluation across all publications, as different error metrics are applied to measure output quality [ ]. our task in this research is to propose measures towards addressing optimal solar energy forecasting by employing a systematic optimization approach based on a hybrid of weather and energy forecast models. after giving an overview of the sustainable energy issues in china, we have reviewed and classified the various models that existing studies have used to predict the influences of the weather influences and the output of solar energy production units. further, we describe the process of solar energy forecasting and establish the relevant parameters, settings, and other exogenous influences for selecting the appropriate model against that background. next, we evaluate the performance of an exemplary ensemble model which combines the forecast output of two popular statistical prediction methods using a dynamic weighting factor [ ]. figure : provincial map of china showing the location of jiangsu province, adopted from [ ]. following proposal for further studies in existing litera- ture, this study describes essential forecasting ideas in respect of energy planning and discusses their application in the jiangsu province which is one of the areas in china where solar energy is gaining significant attention (figure shows the map of china indicating the location of jiangsu province). finally we outline the additional research directions for our future work. thus, a study on criteria for forecasting methods of solar power could help to determine its sustainability in the long term and capacity to support grid power supply [ ]. further this study is important as it seeks to act as benchmarks for rationale power policy development in global and local contexts and determination of rationale power information systems could be managed [ ]. . renewable energy investment in jiangsu currently the chinese energy demand is largely dependent on coal and crude oil and hydro based energy sources. recent studies have documented the possibility of increase in demand of power from current – tonne watt per hour to – tonne watt per hour. the increase in energy demand against decreasing coal-reserves presents possible future challenges and risks of energy crisis or possible economic crisis in china that may arise from energy crisis, aspects that may have more negative economic and financial impacts than was experienced during s global financial crisis that was linked to oil crises; [ ] explains that the prospect of exploiting full capacity of solar power cannot be done in haste due to high level of planning and quan- tification measures that ought to be done and long period that is needed to implement solar power (china national committee for the implementation of the un convention to combat desertification) [ ]. this means that the economic and social developments in china may continue to rely on the scientific world journal coal and crude oil driven machines due to inability to produce enough alternative sources such as solar energy, wind energy. prabhu [ ] proposed possibilities of continuity in the use of coal or nonrenewable sources of energy to power national grid system due to high losses that are associated with solar power supply at the point of generation. however this system thinking approach, where high power losses occur at point of generation, could result in nonuse of solar power in large scale or in commercial purposes. but this has been negated by peidong et al. [ ] who proposed that future development of solar power and other renewable sources of energy is important due to lack of sustainability of non-renewable sources of energy from social, economic, and environmental perspectives. this implies that, in china, as emerging higher consumer of electric power, there is, a need for development and innovation of solar power. again, according to qu et al. [ ], high energy losses occur at the point of production of solar power which implies that the net energy output (neo) that is eventually supplied to the national grid system is lower. further, as later studies by fan et al. [ ] found, the sellable electricity output from solar farms is very low. the costing of sellable solar power is calculated as a difference between loss of energy output (leo) and gross energy output (geo) to give net energy output (neo) which is documented din literature to be a range between % and %, from sellable energy percentage of % and %. for all practical purposes, [ ] indicates that solar firms or solar power generators cannot achieve gross energy output (geo) that is dependent on onsite measurement data and variability of local solar resources. reference [ ] indicate that that differences in geo arise because different factors are not taken into account when calculating geo. some of these factors include (i) wake effect of solar turbine generator system, (ii) electric equipment which also consumes part of generated power, (iii) line losses due to type of wires used and distance that the power is transmitted from production site to consumption point, (iv) presence of the wake effect of solar-turbine generator systems, (v) stability or instability of solar speed for turning turbiness, (vi) changes in the directions of solar leading to variation in the quantity of solar power that is generated, (vii) changes and variation in weather and climate for instance low or high temperatures and their impacts on air density, (viii) on-site air density and variation of air density, (ix) solar farm electricity needs and consumption in the solar farms, (x) guarantee of power curve of wake effect of solar turbine generator system. there are fears that solar power may fail to support economic developments the way coal or crude oil power has figure : map of chinese power grid, adopted from [ ]. supported economic developments. however, the high rate of economic development from coal has resulted in increased environmental and resources pressures. for instance, in , in china, acidic rain is documented to have affected over % of chinese land mass. this implies that crude oil and coal as power sources are more pollutant compared to solar power. in addition, solar power does not preclude development of global energy and global power solution. reference [ ] has indicated that the current amount of money that will cost jiangsu to produce renewable energy is among the highest compared to other options but this cost is actually the initial set-up cost but largely lower when it is spread over its useful life and the consideration is given to other associated social costs. in other words, if renewable energy is compared with other forms of energy such as coals and hydro, on the basis of environmental impact, then using renewable energy is far cheaper in the long term as it helps to bring significant improvement in environment and reduces the susceptibility to other forms of diseases that could have been incurred compared to the high social cost of the rest which are still struggling to get improved technology to make their processing better. it is the estimation of zhong [ ] that by the end of the year the prices of domestic renewable energy technology will decline by averagely less than , rmb/kw. since the renewable energy industry all over the world and in china in particular is gradually developing, the trend in prices will continue to decline by about % in and even till about a decade afterwards and will reduce by % per decade [ ]. it is the confident estimation of [ ] that by the year , the prices of renewable energy technology may hit as low as , rmb/kw or even lower at , rmb/kw due to the expectation of the emergence of the new efficiency technologies that will make it cheaper to produce and operate the renewable energy technology. on the other hand it is also the case that the unit cost of operating the solar power turbine was going to . rmb/kwh [ ]. figure shows the map of chinese power grid. it has also been estimated by zhipeng [ ] that by the end of the year , the total investment in the solar power if it is looked at from a high scenario perspective will reach the scientific world journal energy forecast models physical statistical hybrid naïve prediction similar days stochastic time series machine learning multivariateunivariate figure : classification of energy forecasting models, adopted from [ ]. about . trillion rmb, but with an intermediate scenarios the expectation will be that the total investment cost will be . trillion rmb. on the other hand the low scenario will lead to a total investment cost of approximately . trillion rmb. from the above analysis and in comparison with other approaches to power generation, xiaoliang [ ] presented evidence to support the claim that not only is renewable energy generation environmentally friendly, thereby having the possibility of reducing the cost of operations in one country as it is in the case of china, but also it has lower operating cost based on all sensitive analyses to the point that even the worst case scenario of costing appears to be more favourable than other methods such as the coal fired energy sources [ ]. that notwithstanding it is important for china to target the best case scenario of achieving the lowest cost production and investment since it is within the reach of achievement. again a recent study [ ] categorizes the superiority of solar power energy into three main areas and these are explained below. . energy supply forecasting approaches within the existing literature there are several approaches to energy supply prediction; however, the time series remains a common and classical tool for applied energy prediction analysis. according to alfares and nazeeruddin [ ], the extant literature is inundated with a long and rich history of forecasting electricity load or demand using a range of very sophisticated but high-quality models. however, the necessity for having specialized energy supply forecasting approaches remains a fairly new topic and hence has limited number of studies. the recent interest in energy supply fore- casting is largely because of the challenges of grid-connected res penetrating the distribution systems. notwithstanding, both energy demand and supply forecasting approaches make use of similar or related techniques. generally, there are generally two main approaches to energy supply forecasting and these are the weather forecast models and the energy forecast models. figure shows the classification of weather forecasting models. according to chen et al. [ ] the weather forecasting models are computed based on the assumption that energy supply predictions must be done rationally if one wants to get a good forecast. they further explain that a good prediction of the solar energy output is will depend on a good forecast of the solar irradiation. consequently, using a precise weather forecast model is a functional prerequisite for obtaining or generating a reliable energy output model. this view is shared by dorvlo et al. [ ] who also argue that even though determining the quality of the solar irradiation is orthogonal to the core activities of a grid operator (this is the core work of the meteorological services), having a basic understanding of the underlying principles helps in choosing a specific energy output model. wu and chan [ ] present series of approaches under the weather forecasting models some of which include the numerical weather prediction, the cloud imagery and statistical models. each of these models has different submodels used in enhancing effective prediction. for example, under the numerical weather prediction researchers have used approaches such as the european center for medium-range weather-forecasts model (ecmwf), the global forecast system (gfs) from national centers for environmental prediction , or the north american mesoscale model (nam). while the numerical weather prediction models above are modern and common method to predict a number of variables by describing the physics and dynamic of the atmosphere, which are then used to derive the relevant weather influences at a specific point of interest, the cloud imagery approaches are relatively different [ ]. using either the satellite data approach or the total sky imagers approach, cloud imagery hinges on the influences of local cloudiness where it is considered to be the most critical factor for the estimation of solar irradiation, especially on days with partial cloudiness where abrupt changes may occur. with the statistical models the treatment of solar radiation forecasting is based on data on historical observation through the use of simple and common time series regression models like arima, artificial neural networks (ann) or fuzzy-logic models (fl) [ ]. according to reikard [ ] after comparing various regression models, arima in logs with time-varying coef- ficients performs best, due to its ability to capture the diurnal cycle more effectively than other methods [ ]. it is further the contention of wu and chan [ ] that combining arma and a time delay neural network (tdnn) is the best while [ ] also posit that a hybrid of multilayer perceptron (mlp) the scientific world journal weather forecast models numerical weather prediction ecmwf gfs (ncef) name (ncdc) cloud imagery satellite based total sky imager statistical models arma/tdnn arima anfis rbfnn mlp figure : classification of weather forecasting models, adopted from [ ]. and radial basis functions (rbf) which are both ann- models simpler and precise. on the other hand mu et al. [ ] compares the performance of adaptative network based fuzzy inference system (anfis) against autoregressive mod- els (ar) and ann. for this reason [ ] think that using a statistical model as those above is considered being domain- neutral. on the other hand it is the contention of cai et al. [ ] that when the outputs have been generated from any of the weather models described above, they must equally be converted into energy forecast models. currently the main energy forecast models or methods include categories of physical, statistical, and hybrid methods as shown in figure . according to cai et al. [ ] the physical models embraces all the energy supply forecasting approaches that rely on a renewable power plant’s technical ability to convert the meteorological resources collected into electrical power. it considers the external influences derived from nwp, local topography, and atmospheric conditions. they are fitted to become an accurate set which has no need of historical output curves. with the local topography, this becomes suitable for the estimation of future output of planned or recently installed res units. while some levels of solar energy supply predictions have been made by applying physical models, the most frequent and suitable area for their use is in predicting wind energy supply [ ]. when it comes to the statistical models for predicting energy, the work of [ ] has explained series of them which are used under different conditions. the first of these is the naive prediction model. in this approach considered as the most straightforward of the statistical models naive guess is made by assuming that next periods’ expected energy output will be equal to the observations of the current period 𝑃𝑝. the next statistical approach to energy prediction is the similar-days model which is based on the concept of diurnal persistence, improved forecasts. this is computed by selecting related historical days with appropriate similarity of time series measures [ ]. these models are the most popular for forecasts loads under situations where the weather awareness plays an insignificant role in relation to how consumption cycle derived from historical data influences forecast load. in case of solar energy forecasts, similar-days models are used in instances where there is no nwp available at all or the prediction error included naturally in the nwp is estimated as too high to provide reliable energy output forecasts (bolinger et al. [ ]). with the stochastic time series models for energy supply forecasting, it is the contention of [ ] that this depends on the total number of parameters that influences the models. there are two groups of main approaches to energy supply forecasting in the model and these are univariate and mul- tivariate models. while the univariate employs exponential smoothing for effective one-period ahead, the multivariate model allows for the integration of exogenous parameters. finally there is the machine learning model to energy supply forecasting. this approach is the most common approach to forecasting a time series’ future values. this is because it appears to be the best alternative to conventional linear forecasting methods. in the existing literature, the ann has been applied more successfully in forecasting the rate of energy supply fluctuation. ann learns to recognize patterns in data using training data sets. for example, the use of neural networks is proposed by frank et al. [ ] due to their examination of the feed-forward (ffnn), the radial basis function (rbfnn) and the recurrent neural network (rnn) for solar power fore- casting based on nwp input and historical observation data. a similar approach is described by [ ] where a rbfnn is combined with a weather type classification model obtained by a self-organizing map (som). in contrast, tao et al. compute hourly energy forecasts using an adaptive narx network combined with a clear-sky radiation model, which allows for forecasts without including nwp data and still outperforms nonadapting regression based methods. . argument for hybrid method according to kleindorfer et al. [ ] the challenge with adopt- ing a single approach top prediction is often the uncertainty that comes with it. the process of planning and predicting is generally an attempt to make a good guess of an uncertain future based on what is happening today. for this reason the ability to get different predictive tools to validate results is essential in effective planning that reduces the risk exposure. in essence the hybrid models refer to the combination of any the scientific world journal two or more of the above methods that have been described. according to jensen [ ] using hybrid approaches to predict energy supply pattern has become a very popular approach because of the fact that it gives the opportunity to take advantage of the strongest points of different stand-alone forecasting techniques [ ]. the basic idea of combining models is to use each method’s unique features in capturing different patterns in the data. theoretical and empirical findings from other domains suggest that combining linear and nonlinear models can be an efficient way to improve the forecast accuracy [ ] so hybrid models seem to be a promising approach that can potentially outperform nonhy- brid models individually. awerbuch [ ] provides a successful example of how hybrid approaches can be applied thus setting a context as to the extent to which this can be applied within the context of chinese jiangsu province where solar energy is gaining some level of appreciation over the last couple of years. specifically in this study we provide an analysis of the impact of the parameters for the selection of energy models for forecasting solar energy supply including the model combination task. from them we compare the total supply quantity forecasted using two stochastic models belonging to the multivariate class: (a) a simple linear model based on principal component analysis and multivariate regression from the mirabel project and (b) a commercial library using the more complex non-linear mars algorithm. the forecasts are compared both individually and in com- bination against a naive, weather-unaware reference model (ref) based on the similar-days method. similar models have been used within the context of germany by [ ]. it is however uncertain as to whether differences in geographical location identified as an important factor in solar energy prediction will affect the level of success of the application of this model in jiangsu province in china. . materials and methods . . data and setting for experiment. recent studies into prediction market have led to the introduction of model selection criteria of spatial aggregation. in order to cope with this challenge the study included three different observations of solar energy output curves into our adopted scenario. firstly a single, disaggregated pv-installation located in central jiangsu town of nanjing which is incidentally the provincial capital was chosen and is denoted in our model or scenario as da. secondly the scenario also considers the aggregate of all pv-installations available that is measured in the same local distribution system and this has been denoted as ds. thirdly our model equally has an aggregation of all pv- installations attached to the superior transmission system. this however is denoted as ts. the ability to obtain this information requires some level of cooperation; hence, da and ds data were provided by a cooperating distribution system operator, while data category ts was obtained from a public website. all-time series have a resolution of minutes and cover june to june . the study picked data on weather which included mea- surements of solar irradiation, air temperature, and wind speed with a resolution of hour from a nearby weather sta- tion operated by the meteorological services in the province. this was an appropriate source because it is located within the range of the distribution networks. the reason why only the observed weather data was used is because of the ability to eliminate the nwp prediction error. this further allows the energy model performance itself to be evaluated with a high degree of accuracy. from our source time series, we made use of the historical data for the first eleven months for the purposes of training and the last month for forecast evaluation. in order for our scenario to account for day-ahead and intraday terms, forecast horizons of two, twelve, and twenty-four hours ahead were defined in consistency with earlier works of [ , – ]. the time thus started each day at : . the model building horizon was adopted following the computation of the forecast. to do this we added the forecast horizon length to the model horizon. this was to extend the length of the available history in accordance with each of the iterations completed. the effect of this was to simulate the integration of newly arriving observations in the forecasting process, which can then be compared with the forecasted values and used to qualify the forecast model. therefore, the number of forecasting models required to cover the whole month was three hundred seventy-two for a horizon of two hours, sixty-two (twelve hours) and thirty one (twenty-four hours), respectively. in order to derive the optimal combination ratio between two analyzed algorithms 𝐴 and 𝐵, the variable perceptual weighting factor 𝜆 was introduced. the final energy forecast𝑃𝐼 𝑡 is then computed by 𝑃 󸀠 𝑡 =𝜆𝑃 󸀠 𝐴𝑡 +( −𝜆)𝑃 󸀠 𝐵𝑡 . ( ) in this equation, 𝑃𝑡 𝐴𝑡 represents the forecasted value of algorithm𝐴 and𝑃𝐼 𝐵𝑡 is the forecasted value from algorithm 𝐵 for a timestamp of 𝑡. . output evaluation a number of different statistical metrics available were used to evaluate the extent to which the values that have been forecasted are of good and realistic quality. according to [ ] it is often the case that the root mean square error (rmse) is desirable when one is measuring or evaluating the criterion for intraday forecasts. the reason is that it is able to address the likelihood of extreme values better than others. with the rmse returning absolute values, we used a normalized form to enable the comparison of the performance of the models on output curves of different aggregation scales. the normalized root mean square error (nrmse) is achieved by nrmse= rmse 𝑃max ∗ . ( ) in this model the 𝑃max represents the maximum observed power output. it was noted that using the percentage dif- ference between observed and predicted power outputs to forecast with day-ahead horizons or above is more inter- esting. this is expressed by the mean absolute percentage the scientific world journal table : quality of forecast results using nrmse evaluation metric. ref 𝜆a 𝜆b da da da ds ds ds ts ts ts % — — , , , , , , , , , % % , , , , , , , , , % % , , , , , , , , , % % , , , , , , , , , % % , , , , , , , , , % % , , , , , , , , , error (mape). following [ ], nondaylight hours (values with timestamps before am and after pm) and all resting sero observation values were excluded from error calculation. this also means that the effects of snow coverage or measurement failures were removed completely from the results. . results of experiment in table , the results of both the linear (a) and non-linear (b) models have been presented. the table shows that both the linear and nonlinear models clearly outperform the similar- days reference model (ref) individually in most of the analyzed cases in terms of nrmse. again the information also shows that generally the nonlinear model gives better results than the linear model and this is an indication of the fact that including the historical values improves the quality of output. notwithstanding, some constellations can be found where model combinations perform slightly better than individual models. with regard to the impact of the chosen forecast horizon, it is observed that the quality of algorithm b decreases with longer horizons and is almost identical to model a for day-ahead periods while model a provides constant values. this can also be explained by the exponential influence of historical values, which has no effect on model a. it is our suspicion that model a can outperform model b on short-term, and midterm forecasts, which have not been covered by the presented scenario. it appears rather surprising that all models show the lowest preciseness on the ds aggregate where a better per- formance was expected than that on the disaggregation da. the possibly included share of self-consumption units (prosumers) may explain the reduction of correlation values, as those measurements are hidden within the observed output curve, thus requiring an individual treatment (e.g., using combined energy demand and supply models) which needs to be further investigated. it is also noted that all models perform best on the highest aggregate. even though the observed correlation of weather information at only one location is not a representative influence on that supra- regional level, the effect of weather-awareness seems to be completely neutralized by the impact of high aggregation. . conclusion our task in this research was to propose measures towards addressing optimal solar energy forecasting by employing a systematic optimization approach based on a hybrid of weather and energy forecast models. after giving an overview of the sustainable energy issues in china, we have reviewed and classified the various models that existing studies have used to predict the influences of the weather influences and the output of solar energy production units. further, we have established the relevant parameters, settings, and other exogenous influences for selecting the appropriate model against that background. finally we have evaluated the performance of an exem- plary hybrid model that combines the forecast output of two popular statistical prediction methods using a dynamic weighting factor. the study has shown that effective fore- casting of solar energy output requires a two-step approach. firstly it requires weather, and energy forecast models. it has been observed that with respect to energy forecast, there are possible choices that can be selected amongst statistical, phys- ical, and hybrid models. the research has further established that selecting an appropriate model is dependent on various conditions, hence, the forecasting step can be considered as an iterative process. from the effectiveness of the hybrid approach as has been found in the analysis of data, it is evident that a hybrid model that combines both weather and energy forecasting models appears to offer additional optimization option. this is especially in the case where there is no model found to individually outperform in all given situations. this has been demonstrated in the analysis against the parameters of forecast horizon and spatial aggregation. notwithstanding we propose that future studies must focus on examining the extent to which complex hybrid forms of energy and weather forecasting models can lead to more efficient predictions. in effect combining many weather forecasting approaches against single energy forecasting approach and vice versa is good enough to start future enquiry into finding the most efficient way of predicting energy supply. the dynamics of solar energy supply in jiangsu province in china still makes it an interesting field to explore any future complex application of hybrid solar energy prediction models. this may provide some opportunities to develop global standards for forecasting solar energy with more efficient and reliable outcomes. conflict of interests the authors declare that there is no conflict of interests regarding the publication of this paper. the scientific world journal acknowledgment the authors wish to express their profound appreciation to china natural science fund (grant nos. and ) for supporting this project. references [ ] j. asafu-adjaye, “the relationship between energy consump- tion, energy prices and economic growth: time series evidence from asian developing countries,” energy economics, vol. , no. , pp. – , . 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( ) : commodities: flight in precious metals, intereconomics, issn - , verlag weltarchiv, hamburg, vol. , iss. , pp. , http://dx.doi.org/ . /bf this version is available at: http://hdl.handle.net/ / standard-nutzungsbedingungen: die dokumente auf econstor dürfen zu eigenen wissenschaftlichen zwecken und zum privatgebrauch gespeichert und kopiert werden. sie dürfen die dokumente nicht für öffentliche oder kommerzielle zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. sofern die verfasser die dokumente unter open-content-lizenzen (insbesondere cc-lizenzen) zur verfügung gestellt haben sollten, gelten abweichend von diesen nutzungsbedingungen die in der dort genannten lizenz gewährten nutzungsrechte. terms of use: documents in econstor may be saved and copied for your personal and scholarly purposes. you are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public. if the documents have been made available under an open content licence (especially creative commons licences), you may exercise further usage rights as specified in the indicated licence. www.econstor.eu comment france supports the proposal of the ec com- mission for a stabilisation fund to prevent the commodity prices from falling below a certain minimum level - a rare instance of agreement, albeit at the expense of all the community's tax- payers, between the bureaucratic perfectionism of the commission and the aims of the french africa policy. this automation however is rejected by the other ec states, italy excepted: evidently taking warning from the similar design of the common agricultural policy, they favour special decisions in each case subject to an overall ceil- ing, and they want to make sure that resources of the stabilisation fund are only used to improve production structures. italy wants long-term sup- ply and purchase contracts instead of a stabilisa- tion fund, with both sides giving guarantees on quantities and on prices or earnings. with such a display of discord in the ec it is difficult to be- lieve in successful conclusion of the association talks by next autumn, kw. mineral resources new measures in germany in west germany, as in all industrialised coun- tries, the energy crisis has given rise to second thoughts on energy and raw material policy. the dependence on imported raw materials is felt to create a critical situation. it is to be lessened in future: a secure raw material basis is the aim. in line with the concept for safe raw material sup- plies it is intended to further international cooper- ation and set up more production plants with german participation in raw material producing countries. the exploration promotion programme is also to be extended to improve the supply of mineral raw materials. selective research, pros- pecting and exploration are to be covered by guarantees and tax incentives. in its raw material policy, and more particularly in its oil policy, the federal republic's approach has on occasion been somewhat unfortunate. one often hears of the disadvantageous division of the seabed of the north sea: the german sector seems to be rather barren. but why should so much weight be attached to this fact when the north sea - with p.c. of the world's oil and p.c. of its gas reserves - counts for so very little on a world scale. more subtlety could have been shown when deminex went for a participa- tion in abu dhabi: given a proper structure, this joint enterprise of german mineral oil firms which was formed in could yet become a suitable instrument for securing oil for the federal re- public. the government took a new step to carry out its energy programme when it took over the majority of the share capital of gelsenberg for the state intereconomics, no. , and merged the company with veba, another enterprise under state influence. the intention is presumably to create a mineral oil group under state influence. such a group could certainly be more easily guided in international negotiations. whether it constitutes a commendable solution for the dilemma created by germany's dearth of mineral raw materials, however, is another question, iwe. commodities flight in precious metals venerated by some as the ultimate standard for valuing all means of payments, disqualified by others as a barbaric metal and relic of a feudal age - gold is experiencing an undreamt-of renas- cence in its function as a means of hoarding capital. huge turnovers amidst scenes of panic and speculative boom in precious metals were a feature of the worldwide flight away from paper money and into commodities. the market price of gold which had already broken through the record mark of $ per ounce during the boom went up by about p.c. in the first two months of this year. the prices of the "white" metals, silver and platinum, doubled at the same time. that they soared so much higher is attributed to the impact of speculation: metal market facil- ities for speculation are available in these metals - in contrast to gold - and they are not subject to any restrictions. the flight into the precious metals is degenerat- ing into an international mass movement. terrified by the galloping money depreciation and frequent monetary crises or else emboldened by the hope of profits from lucrative speculation, versed big investors and small savers alike are turning their backs on paper money and putting their trust in precious commodities. the traditional forms of investment in the stock, bond and property mar- kets ceased long ago to offer a credible alterna- tive to those who, for reasons of safety or specu- lation, want to put their money in real assets. the higher prices of precious metals are, besides, backed by sound calculations based on stagnat- ing production, rising operational costs and grow- ing demands from industry. a threat is, however, emerging for the silver mar- ket through the easing of the indian export regu- lations for silver and the lifting of the us embargo on the holding of gold. the price of gold, on the other hand, would be hit severely if the official price were raised and the monetary authorities were to sell gold in the market. the central banks, which hold about half of all gold stocks, could try this way of countering balance of payments diffi- culties and foreign currency stringencies result- ing from the massive oil price increases, zz. europe during the energy crisis econstor make your publications visible. a service of zbw leibniz-informationszentrum wirtschaft leibniz information centre for economics standke, klaus-heinrich article — digitized version europe during the energy crisis intereconomics suggested citation: standke, klaus-heinrich ( ) : europe during the energy crisis, intereconomics, issn - , verlag weltarchiv, hamburg, vol. , iss. , pp. - , http://dx.doi.org/ . /bf this version is available at: http://hdl.handle.net/ / standard-nutzungsbedingungen: die dokumente auf econstor dürfen zu eigenen wissenschaftlichen zwecken und zum privatgebrauch gespeichert und kopiert werden. sie dürfen die dokumente nicht für öffentliche oder kommerzielle zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. sofern die verfasser die dokumente unter open-content-lizenzen (insbesondere cc-lizenzen) zur verfügung gestellt haben sollten, gelten abweichend von diesen nutzungsbedingungen die in der dort genannten lizenz gewährten nutzungsrechte. terms of use: documents in econstor may be saved and copied for your personal and scholarly purposes. you are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public. if the documents have been made available under an open content licence (especially creative commons licences), you may exercise further usage rights as specified in the indicated licence. www.econstor.eu energy" problems europe during the energy crisis by dr klaus-heinrich standke, paris* shortages of fuels and raw materials had been predicted for the world not before the turn of the century, and even experts were surprised that a situation of general undersupply arrived so soon. as there is little scope for substitution, and the currency system of the world is in peril, industrialised nations have only a narrow field for remedial action. in the long term, there may be some hope, however, for breaking out of the dilemma with the aid of a new technology. w ith a view to the energy crisis and its incipient worldwide effects, the us news magazine, time, stated that was the last year of the past whilst would be the first year of the future. that this new historical era had to begin now, and not in the 'eighties or 'nineties of the present cen- tun/, was a shocking surprise even for the most pessimistic futurologists. both these futurologists and experts on energy, almost without exception, had restricted their predictions to simple extrapo- lation of present trends of energy consumption for painting the immediate and the longer-term future, and to comparing the hypothetical demand for energy with the anticipated supplies of energy. unexpected arab actions pointing especially to the possibilities of nuclear energy developments, many believed that world energy supplies were unlimited and virtually se- cure. it is only a few months ago, the well-known basle economist, bombach, opined: "the spectre of a general energy bottleneck has been well and truly laid." in its place, he warned of a much more terrible danger that was rife: that of thermal pollu- tion. energy experts, including professor schaefer of munich, also saw in thermal overheating of con- urbations the decisive obstacle in the way of growing energy consumption which would prob- ably define the outer limits of this growth. even the highly meritorious "club of rome", which has probably contributed, with its publications, more to waking up humanity to the problem of limited growth than all the herman kahns of this world, has either neglected or attributed too little impor- tance to the political forces that might restrict the availability of the world's resources. practically nobody had thought it possible that the oil sheikhs could ever join in a united front, and * counsellor in the oecd secretariat in paris, has been seconded, since , as secretary-general, to the oecd-sponsored eirma (european industrial research on management association) paris. dr standke is also assistant professor at the ecole des hautes etudes commerciales (hec), d~partement affalres intematlonales, st jouy-en..josas. that they were able to do so has painfully reminded the powerful and mighty in industrialised countries' politics and economies how dependent these coun- tries are on some of the less-developed nations - though this dependence had been discernible for a long time past and was felt as more and more depressing. from now onwards - and this will probably be the watershed from which we descend into the "new age" - western industrialised so- ciety has to get used to the fact that the two sets of problems connected with the physical limits of the world's resources, and with environ- mental factors, are being supplemented with a third one which is of a significance superior to the ear- lier ones: political limitation of available supplies. oil not the only problem the question arises not only with regard to oil, though present disputes about the energy supply crisis might make us believe this. nor is it - as some western politicians seem to believe - simply a changeover from the difficulty of obtaining suffi- cient quantities to the question of whether we can afford the prices charged for supplies. we have instead become eyewitnesses of a total reshuffling of the cards with which the game is played. it is often forgotten that the rules of the game have remained unchanged: they are the same that were formerly used by the industrialised countries for engineering their own economic growth. they are nothing but the rules of supply and demand and their interdependence. after world war ii, the western democratic coun- tries stood in the forefront of the powers that built the united nations organisation. uno was organis- ed in a democratic way. it was an important experi- ence for the self-respect of the younger nations of the so-called third world (of which the uno major- ity consists) to see that, when a vote was taken, their votes had the same weight as those of the "older" industrialised nations and those of the socialist camp. that both west and east tried to intereconomics, no. , energy problems curry favour with ldcs has put this self-respect on an even firmer basis. but even without the recent war between arabs and israelis and its political and economic after- effects, the end of industrial affluent society with its perpetual surplus production and its laissez- fairs policies could be foreseen. in his last christ- mas address, the president of the federal republic of germany, dr heinemann, quoted the former eec president, sicco mansholt, who had stated during the summer of : only a full-scale disaster could force our industrialised society to change course, and such a disaster would then help us to evade an even worse catastrophe. based on similar thoughts, the financial times wrote in november, , that we should really be grateful to the arabs for having forced us, against our own will, to rethink and revise our aims and the future possibilities of our development. during the discussion about the limits of growth, it had become obvious that our present world could barely maintain in the american style of life no more than perhaps , million people but never the present living population of the world of about , million. yet it had been the professed aim of all the other industrialised countries including the socialist camp to emulate the american stand- ard of living. the miscalculations grow even clearer by reflecting that at the turn to the next millenium - which, historically speaking, is only a few years distant from our age - the world's popu- lation will have almost doubled, and that this kind of growth will affect mainly the countries of the third world. it is also known to us that energy consumption has become the clearest indicator of any nation's prosperity. the usa has a population that repre- sents p.c. of the world's total population, but this population consumes nearly p.c. of the world's energy supplies. similar relations hold good for all important raw materials. these few figures alone reveal how perilous is the continued squandering of the raw material resources of the world, which the club of rome foresees, already in the short term. nobody seems to have foreseen the chance for commodity-producing countries to profit from the rising dependence of commodity-consuming coun- tries, through political means. through the cen- turies of colonial dependence, coloured people have accumulated so much ill-will against their "white masters", who were able to do everything and, in the end, owned everything, that it had even- tually to find an outlet. only on this background will it be possible to understand the emotions which flow into to-day's haggling about quantities and prices of oil and of other raw materials. in this situation, it is a weak consolation for western in- dustrialised countries that, from the viewpoint of ldcs, bot they and the socialist countries of the soviet bloc are in the dock together, though the communist countries are less dependent on com- modity supplies from the third world, because they themselves are less developed, and because the soviet union owns vast mineral deposits. but what would be a practicable way out from this inexorable dilemma for both governments and the economies of western industrialised countries? of the three major difficulties - the supply of energy, raw materials, and food, the present article will deal only with the former two, without wanting to minimise the danger that is most threatening to the human race, the predictable insufficiency of food supplies. at the present time, it is the oil crisis that seems most acute, and it has turned already into a gener- al energy crisis. three ways to overcome it are conceivable: political, economic, and research and technological efforts. all the more optimistic and more pessimistic views of experts agree that both in the short and in the medium term, the present energy gap could not be bridged without oil. politi- cal or military reprisals against the opec front of countries are out of the question. gunboat policies, in this field as in all others, are a tool of the past. western consumer countries, becoming gradually more aware of their impotence, restrict themselves to moralising appeals to the opec governments to act rationally, and they cherish the hope that the cartel of oil producing countries would, one fine day, break up. western remonstrances that sales prices for oil had been pushed up to unacceptable heights are being countered by the oil countries through the pointer that final consumer prices still contain a very much higher share of consumer countries' fiscal imposts than the producer's revenues. besides, they use the classical argument of the monopolist that nobody is compelled to buy their crude. the world currency system in peril the exhortations of western economists and politi- cians thrown into the debate that the immense deficits on international trading account, on the one hand, and the correspondingly vast surpluses of producer countries, on the other hand, cannot but destroy the equilibrium of any conceivable world currency system, must be taken as seriously as possible. western industrialised countries will have to carry, through the next few years, annual net outgoings of the order of us $ to bn. the accumulation of such surpluses in the producing countries' coffers would create funds of such im- mensity that they would be far bigger than the cur- rency reserves of all the western industrialised countries taken together, within a small number of years. intereconomics, no. , energy problems the general situation is being aggravated by the fact that sparsely-populated countries, including saudi arabia, kuwait, libya, etc., can hardly cope with the problem of exchanging their billions and billions of future revenue against investment and consumption goods. on the other hand, they have only limited chances to invest these funds fully in oil consuming countries or in other investment chances offered by the relevant centres of western finance. on the other hand, the crude-exporting countries are fully aware of the fact that their crude reserves, at the rate at which they are now being exploited, cannot but be almost depleted within the measur- able future - current estimates quote the next years as the outer limit. who can seriously grudge them in this situation that they "require their own with usury" (luke, chap. ), as far as they are able to do so? visualising these facts as they are, it appears unrealistic to believe in the frequently- heard assertion that the oil crisis is not a problem of available quantities but one of fair prices. limited chances for substitution the suggestion, on the contrary, that opec coun- tries might decide to gear their crude production mainly to serving their own economic requirements and not, as in the past, the needs of consumer countries, seems more likely. even if oil would cease to remain a source of energy - which is higly improbable - it would still remain, for ever, a raw material for the chemical industry, for which no substitution is possible. for this purpose, about p.c. (but with a rising trend) of available sup- plies are being used at present. whether the western nations could be forged into a more united front by the oil crisis is, unfortunate- ly, no longer a question that requires an answer. the trend goes in the opposite direction: the crisis has revealed how brittle the atlantic alliance is, and how the members of the european community are driven into different directions by their national interests. in exploring the prospects of the energy conference called by president nixon to washing- ton in february, james reston of the new york times expressed himself with much scepticism, mainly because all important western countries, at the time, were headed by weak governments. looking over their shoulders for the reaction of their electors, all these governments would there- fore attempt to reap the maximum advantage from bilateral negotiations with the oil-producing states. the slogan: sauve qui peut was also the guideline for the governments of the most important indus- trialised countries, when they drew up their in- dividual programmes for energy research. for the time being, nobody thinks of coordinating these programmes, let alone of pooling available re- sources. the only country that is relatively inde- pendent of arab oil shipments is the usa. already in november , president nixon proclaimed his "project independence", which will be funded by amounts which are inconceivable under west euro- pean conditions, in order to make the usa self- sufficient in energy by . as the published plans go, it is even intended to make the usa again a net exporter of energy. oil as an industrial raw material after having reviewed the discouraging prospects of tackling the energy crisis by political efforts, its purely economic effects have to be surveyed briefly. in doing so, it must be stressed that dif- ferent branches of industry are dependent on oil supplies to a varying extent. industry in the federal republic of germany covers about one third of its energy requirements by oil. in reference to turnovers the share of fuel oil is largest in cement- and brick-works as well as in paper processing. counted in absolute figures, by far the leading oil consumers are the industries quarrying and pro- cessing stone and constituents of the soil, the chemical and the iron and steel industries, and generally, mineral processing. however, counting oil consumption in per cent of a given industry's harburger oelwerke brinckman & mergell ll 'llla u u hamburg-harburg manufactures of edible oils and raw materials for margarine in top quality loadin e i m the i n d w t r y f e r yearj intereconomics, no. , energy problems total energy needs, it will be found that - apart from iron and steel making, chemistry, and non- iron metallurgy - practically all industries draw more than , and a good number of them more than , p.c. of their total energy requirements from oil. it has to be specially underlined that oil is an indispensable raw material for the chemical indus- try and for other industries dependent on it in- cluding the textile industry and plastics processing, and that, naturally, also the automotive industry, with its thousands of sub-contractors and sup- pliers, is firmly tied to the price and the volume of oil supplies. all these industries are subject to perpetual changes of their structure, and this proc- ess will be accelerated by the energy crisis. in the past, market shifts, problems of location, an adverse cost structure (especially in the field of labour costs) were the prime movers of such struc- tural changes, but from now on, costs and avail- ability of energy and of raw materials will be the additional and decisive force which determines the course of further developments. inevitable geographical shifts more shifts in industrial locations than in the past are to be expected. it is to be foreseen that the combination of costs, including wage levels, raw materials and energy prices, will enforce novel forms of the international division of labour. entire branches of industry will lose their competitiveness in their countries of origin and will have to emigrate to ldcs. other industries may be compelled to leave their original domiciles under the pressure of conditions imposed on them by the governments of raw material and oil exporting states. reflecting a closely related trend, the classical home coun- tries of industry will aid and abet ldcs in building up their own industries. ldcs are averse to limiting their industrial activity to the extraction of their mineral resources and wish to develop processing industries up to a high degree of sophistication, and to share in marketing their products. the shah of iran seems to be typical for this atti- tude, provided that it is true that he recently stated that, after another ten years, "not a drop of iranian crude will be sold abroad, but western industrialised countries will be offered the chance to buy aspirin and other chemicals from iran." it remains to be seen whether these and other ambi- tious plans will ever come to fruition, but we should become accustomed in good time to industrial power being redistributed worldwide soon. oil exporting countries, obviously, had underesti- mated for a long time the power potential of their monopoly position, but now that it is being ex- ploited, it provides a strong spur for other raw material suppliers to profit from the dependence of industrial countries on their commodity exports in a similar way as opec members have done. vital raw materials for european industry can be supplied only fractionally from national resources: the percentages in the case of copper are about . p.c., of tin . p.c., of lead . p.c., of zinc . p.c. a p.c. dependence on overseas sup- pliers is inevitable in the cases of all tropical and sub-tropical products, e.g. coffee, cocoa and tea, phosphates, cotton, etc. the hectical rise of the prices for the most important commodities traded in the world commodity exchanges is frightening. the countries of the soviet bloc, which are often important suppliers of raw materials and semi- finished products to western industries, have joined this drive for higher prices unhesitatingly. incentives for technological innovations for many people's thinking the oil crisis has sud- denly strengthened the incentives for the indus- trialised countries to use their ingeniousness and imagination for inventing new technologies and methods for economising in the use of energy that has now become so precious and of all raw materials whose prices are inexorably rising, be- cause they have become scarce. the two classical indicators for economic operations, the capital requirements and the manpower requirements, will be supplemented by a third one of equal im- portance: the fuel and raw materials requirements. since a large part - experts are even of the opinion: the major part - of energy consumption is sheer waste, energy-saving methods in industry and domestic heating and lighting could help to close the energy gap without any undue tightening of the belts. energy-saving appliances are bound to become a large market for industry. high capital costs, which, to a large part, will remain inflationary for a long time because of the oil price policy of the producers, set up a strong incentive for industry to apply its research and development efforts to finding new, capital-saving methods and techniques. the same incentive operates in the use of raw materials and in en- couraging their recycling. coal will see a revival, both as a source of energy and as raw material. however, the most important source of energy for the future is, according to the unanimous judg- ment of all experts, nuclear energy. during the period of transition, nonetheless, until sufficient atomic energy becomes available, especially eu- ropeans will have to heed the advice of the pres- ident-designate of the american industrial re- search institute, a forum of research-oriented big us industry, dr a. bueche of general electric, who said in his winding-up speech at the autumn congress of iri in chicago: "be nice to the arabs." intereconomics, no. , sustainability article foreign direct investment in the power and energy sector, energy consumption, and economic growth: empirical evidence from pakistan rashid latief * and lin lefen * college of finance, nanjing agricultural university, nanjing , china * correspondence: @njau.edu.cn (r.l.); lefenlinna@njau.edu.cn (l.l.) received: november ; accepted: december ; published: january ���������� ������� abstract: pakistan significantly contributes to the overall economy of south asia, but, for many years, it has been facing a severe energy crisis. despite the robust economic growth and a sharp increase in energy demand, no deliberate efforts have been made to meet the energy demand of the country. similar to other developing countries, foreign direct investment (fdi) plays a key role in the economic development of this country. pakistan receives fdi from many countries in various sectors of the economy. this paper aims to highlight the present situation of the power and energy sector of pakistan (pesp), and empirically analyze the causality among the fdi in the power and energy sector, the energy consumption, and the economic growth of pakistan for the period – . the johansen co-integration and granger causality tests were employed to find the causal relationships among the variables of interest in the short-run and the long-run. the sector-wise flow of fdi reveals that the power and energy sector of pakistan (pesp) has comparatively received a higher amount of fdi than other sectors of the economy in recent years. furthermore, trends of energy production and energy usage reveal a substantial gap in previous years. the results confirm a positive bi-directional short-run causal relationship between economic growth and energy consumption. the results also reveal the presence of long-run causality in the equation of energy consumption. considering the current situation of pesp, policy-makers should formulate policies to attain the minimum debt level and discourage loan-based investment. such policies would be helpful to control the severe energy crisis and increase economic growth. keywords: fdi; energy consumption; economic growth; power and energy sector . introduction at present, investment appears to be a significant factor in the economic development of any country. specifically, foreign direct investment (fdi) constitutes the main source of economic growth in developing countries. over the past few decades, globalization has helped to promote strong economic integration between countries. the developing countries have changed their economic policies by pulling down hurdles in the way of foreign trade and investment. consequently, severe competition exists among developing countries to attract fdi. fdi is helpful for developing countries, such as pakistan, in many ways. first, it offers capital to generate positive externalities, such as employment generation, the transfer of technology, managerial skills, productivity gains, research and development, and new ways of production, in the country. second, it encourages domestic investors to invest in the country [ ]. currently, pakistan lies on the radar of foreign investors globally despite different political and economic challenges. indeed, pakistan has adopted investment-oriented policies to create opportunities for foreign investors. sustainability , , ; doi: . /su www.mdpi.com/journal/sustainability http://www.mdpi.com/journal/sustainability http://www.mdpi.com https://orcid.org/ - - - http://dx.doi.org/ . /su http://www.mdpi.com/journal/sustainability http://www.mdpi.com/ - / / / ?type=check_update&version= sustainability , , of pakistan receives fdi from different countries around the world, such as china, the united states, japan, norway, the united kingdom, hong kong, saudi arabia, and switzerland. the target sectors for fdi include the power and energy sector, financial business, trade, construction, transport, textiles, and trade. the power and energy sector of pakistan (pesp) is one of the major sectors that receives a higher amount of fdi. recently, the government of pakistan (gop) has announced a new power policy and offered different incentives for encouraging domestic and foreign investors to invest in the power and energy sector [ ]. energy is an essential input to economic productivity. moreover, production growth helps to increase the energy demand as a result of an increase in energy consumption [ ]. the level of energy consumption is directly linked to the overall progress of a country. therefore, per capita energy consumption is used as a proxy to measure the socioeconomic development of a country [ ]. similar to other developing countries, the energy demand and consumption of pakistan have consistently increased with the increase in its population. pakistan is facing a severe energy crisis due to its intense reliance on oil and gas, de-rated capacity, circular debt, energy security and threats, and bad governance. to control the energy crisis, policies should be formulated to attain the minimum debt level and discourage loan-based investment. to take an impartial view of fdi in the power and energy sector, it is necessary to analyze the government’s policies to bring a sufficient amount of fdi into the sector and its contribution to the overall economy of the country. to the best of our knowledge, no empirical study has been conducted in the context of pakistan to examine the flow of fdi specifically in the power and energy sector and its impact on economic growth. the aim of this paper is to analyze the causality among the fdi in the power and energy sector, the energy consumption, and the economic growth in the context of pakistan. this paper also highlights the overall structure of the power and energy sector of pakistan (pesp), and major constraints in the progress of this sector. finally, this paper suggests policy implications for the progress of this sector. the rest of the paper is organized as follows. section provides an overview of the power and energy sector of pakistan (pesp), major constraints on this sector, and the contribution of fdi to the development of this sector. section reviews the research work completed by other researchers on the relationship between fdi, energy consumption, and economic growth. section details the data collection, empirical models, and the empirical approaches adopted. section demonstrates the empirical results of this paper. section concludes the study and sketches the policy implications. . overview of pakistan’s power and energy sector . . the structure of pakistan’s power and energy sector the overall structure of pakistan’s power and energy sector consists of different players from the production stage to the final usage as depicted in figure . the following are the major players that are involved in the sector. . . . suppliers of primary energy the major suppliers of primary energy in pakistan, such as oil and gas development company limited (ogdl), pakistan petroleum limited (ppl), and pakistan oilfields limited (pol), supply crude oil to the refineries. the refineries refine the crude oil and supply it to the end consumers through oil distributors. pakistan is heavily dependent upon oil and gas resources to meet its energy demand. domestic oil resources are not enough to fulfill the country’s energy requirement. therefore, pakistan imports crude oil, which satisfies about one-third of its total oil demand, from different countries, such as saudi arabia and middle eastern countries, to fulfill its energy demand [ ]. sustainability , , of . . . power generators and power distributors there are three major power generators operating in pakistan: generation companies (gencos), karachi electric supply corporation (kesc), and independent power producers (ipps). the power is transmitted from these power generators and other projects (hydel and nuclear) to the power distributors. the power distributors supply power to the end consumers. . . . end consumers the end consumers, which consume the energy to fulfill their demand, comprise individual households, different industries, government institutes, and transporters. end consumers pay tariffs that are often subsidized by the government in the form of power and fuel subsidies. these tariffs are utilized to make payments at different phases of the energy supply chain [ ]. sustainability , , x for peer review of end consumers the end consumers, which consume the energy to fulfill their demand, comprise individual households, different industries, government institutes, and transporters. end consumers pay tariffs that are often subsidized by the government in the form of power and fuel subsidies. these tariffs are utilized to make payments at different phases of the energy supply chain [ ]. figure . the structure of pakistan’s power and energy sector [ ]. . . major constraints on pakistan’s power and energy sector pakistan has been facing a severe energy crisis for a long time. despite the robust economic growth and a sharp increase in energy demand, no solemn efforts have been made to satisfy the energy demand in the past few decades. the following are the major constraints behind the energy crisis in the country. intense reliance on oil/gas pakistan is highly dependent upon the import of fossil fuel from foreign countries. fuel import is connected with the volatile price structure of oil in the international oil market. in highly volatile circumstances, pakistan pays a higher cost for importing fossil fuel to meet its domestic requirement for producing energy. pakistan spends about % of its foreign exchange reserves on importing fossil fuel from the international oil market. for instance, the oil prices were increased recently in the international market. the higher oil prices and the shortage of funds adversely affected the quantity demand of pakistan for importing oil. as a result, the gap between energy demand and supply was increased [ ]. pakistan has different choices for improving the current situation of the power and energy sector. it can change its power policy by focusing on alternative energy sources, such as hydro projects, wind projects, and solar projects. pakistan requires new dams to fulfill the energy requirement of the country. although pakistan already has a few dams, namely the tarbela dam, the mangla dam, the mirani dam, the warsak dam, and the sabakzai dam, these dams do not produce enough energy to fulfill the energy requirement of the country. figure . the structure of pakistan’s power and energy sector [ ]. . . major constraints on pakistan’s power and energy sector pakistan has been facing a severe energy crisis for a long time. despite the robust economic growth and a sharp increase in energy demand, no solemn efforts have been made to satisfy the energy demand in the past few decades. the following are the major constraints behind the energy crisis in the country. . . . intense reliance on oil/gas pakistan is highly dependent upon the import of fossil fuel from foreign countries. fuel import is connected with the volatile price structure of oil in the international oil market. in highly volatile circumstances, pakistan pays a higher cost for importing fossil fuel to meet its domestic requirement for producing energy. pakistan spends about % of its foreign exchange reserves on importing fossil fuel from the international oil market. for instance, the oil prices were increased recently in the international market. the higher oil prices and the shortage of funds adversely affected the quantity demand of pakistan for importing oil. as a result, the gap between energy demand and supply was increased [ ]. pakistan has different choices for improving the current situation of the power and energy sector. it can change its power policy by focusing on alternative energy sources, such as hydro projects, wind sustainability , , of projects, and solar projects. pakistan requires new dams to fulfill the energy requirement of the country. although pakistan already has a few dams, namely the tarbela dam, the mangla dam, the mirani dam, the warsak dam, and the sabakzai dam, these dams do not produce enough energy to fulfill the energy requirement of the country. . . . de-rated capacity many energy production units are installed at different places in pakistan, but their energy producing capacity has been de-rated with the passage of time. there are different factors behind this situation, such as mismanagement, a shortage of funds, the availability of oil, and a lack of proper maintenance. for instance, the total installed capacity of pesp was , mw for generating electricity until june . although the power producers were capable of producing more electricity, as a result, pakistan suffered severe load shedding in the subsequent years [ ]. . . . circular debt circular debt is one of the major constraints that pakistan’s power and energy sector has faced for many years. the problem of circular debt arises as the operating energy units face the issue of cash flows with their creditors and suppliers. ss ali and s badar [ ] highlighted different reasons for the circular debt: ( ) the failure of distribution companies to collect due payments from their receivables (mainly government-owned organizations); ( ) the default of distribution companies on making payments to energy producers; ( ) the default of energy producers on making payments to oil companies for purchasing fuel; and ( ) late payments of oil companies to oil refineries. for instance, the figure of pakistan’s circular debt approached billion rupees at the beginning of , and it is the highest figure of circular debt that the pesp has yet faced. out of the total figure of circular debt, . billion rupees were payables, while billion rupees were pending in the form of loans borrowed by power holding private limited (phpl). looking at the receivables, billions of rupees are pending to be received by the central power purchase agency (cppa) from different government and private organizations. this overall situation of circular debt has made the power and energy sector of pakistan more stagnant [ ]. . . . energy security and threats pakistan’s domestic oil and gas resources are very limited. the domestic oil reserves could be depleted within the next years, while the gas reserves are available for the next years. therefore, pakistan imports oil from different countries to fulfill its domestic oil demand. this situation creates grave concerns about energy security. the main threat to energy security is from foreign routes for importing oil, because these might be disrupted at any time due to global conflicts. moreover, the seaports might also be dysfunctional in the case of war between countries. as a result, pakistan’s entire thermal electricity production system could be adversely affected [ ]. the main gas resources of pakistan exist in the provinces of baluchistan and sindh. the political and security situation of these provinces could significantly affect the energy sector. in , pakistan formally inaugurated the iran–pakistan gas pipeline project to import gas from iran. however, this project has not yet been completed, although it was expected to be complete in december . the main reason behind it was the economic sanctions imposed by the united states on iran. moreover, the government of pakistan (gop) has recently negotiated with qatar and started to import lng for fulfilling the energy requirement of the country. conversely, the opponents of this project have filed cases in courts of law. the court decisions are still pending, and could affect the import of lng in the country. sustainability , , of . . . bad governance the power and energy sector of pakistan (pesp) has faced bad governance for a long time. the main reason is the political influence on energy entities from the public sector. the main political parties, which govern the country, have badly damaged the administrative structure of these entities by hiring incompetent employees on a political basis. as a result of bad governance, the pesp has faced non-technical losses and the theft of gas and electricity in highly politically influenced and insecure areas of pakistan. the problem of circular debt is also interlinked with this constraint. . . energy production, import, and consumption the primary energy production and energy usage have deteriorated with the passage of time in pakistan as depicted in figure . there are different factors involved in it. examples are: the intense reliance on oil and gas, a curtailing of the demand for oil in terms of quantity, ignoring hydro projects, circular debt, insufficient funds, bad governance, and political influences. figure highlights that the net energy imports have been increasing gradually, while the commercial usage of energy has increased sharply in recent years. pakistan, like other developing countries, imports crude oil from arabian countries, and lng from qatar, to fulfill its energy requirement. pakistan has also planned to import electricity from kyrgyzstan and tajikistan, and develop many energy projects under the china pakistan economic corridor (cpec) project. sustainability , , x for peer review of . . energy production, import, and consumption the primary energy production and energy usage have deteriorated with the passage of time in pakistan as depicted in figure . there are different factors involved in it. examples are: the intense reliance on oil and gas, a curtailing of the demand for oil in terms of quantity, ignoring hydro projects, circular debt, insufficient funds, bad governance, and political influences. figure highlights that the net energy imports have been increasing gradually, while the commercial usage of energy has increased sharply in recent years. pakistan, like other developing countries, imports crude oil from arabian countries, and lng from qatar, to fulfill its energy requirement. pakistan has also planned to import electricity from kyrgyzstan and tajikistan, and develop many energy projects under the china pakistan economic corridor (cpec) project. figure . trends of primary energy production and energy usage. figure . trends of net energy import, net energy usage, and commercial energy usage. . . the role of fdi in pakistan’s power and energy sector the energy requirements of pakistan are inflating quickly as the population of the country has been following an increasing trend for many years. the gop has taken steps to make sure that there is sufficient energy security to go along with the expansion in natural resources. pakistan has hydro and coal resources, which, if exploited, could be helpful to fulfill the energy requirements of the country in the future. the latest power production policy was announced in by the government of pakistan (gop), in which it offered different incentives to attract domestic and foreign investors figure . trends of primary energy production and energy usage. sustainability , , x for peer review of . . energy production, import, and consumption the primary energy production and energy usage have deteriorated with the passage of time in pakistan as depicted in figure . there are different factors involved in it. examples are: the intense reliance on oil and gas, a curtailing of the demand for oil in terms of quantity, ignoring hydro projects, circular debt, insufficient funds, bad governance, and political influences. figure highlights that the net energy imports have been increasing gradually, while the commercial usage of energy has increased sharply in recent years. pakistan, like other developing countries, imports crude oil from arabian countries, and lng from qatar, to fulfill its energy requirement. pakistan has also planned to import electricity from kyrgyzstan and tajikistan, and develop many energy projects under the china pakistan economic corridor (cpec) project. figure . trends of primary energy production and energy usage. figure . trends of net energy import, net energy usage, and commercial energy usage. . . the role of fdi in pakistan’s power and energy sector the energy requirements of pakistan are inflating quickly as the population of the country has been following an increasing trend for many years. the gop has taken steps to make sure that there is sufficient energy security to go along with the expansion in natural resources. pakistan has hydro and coal resources, which, if exploited, could be helpful to fulfill the energy requirements of the country in the future. the latest power production policy was announced in by the government of pakistan (gop), in which it offered different incentives to attract domestic and foreign investors figure . trends of net energy import, net energy usage, and commercial energy usage. sustainability , , of . . the role of fdi in pakistan’s power and energy sector the energy requirements of pakistan are inflating quickly as the population of the country has been following an increasing trend for many years. the gop has taken steps to make sure that there is sufficient energy security to go along with the expansion in natural resources. pakistan has hydro and coal resources, which, if exploited, could be helpful to fulfill the energy requirements of the country in the future. the latest power production policy was announced in by the government of pakistan (gop), in which it offered different incentives to attract domestic and foreign investors to invest in power projects. the major aims of this policy are the following: (a) to supply an adequate power production capacity with the minimum cost; (b) to boost up, and make sure of, the exploitation of domestic resources; (c) to provide a win–win situation to all key players and obtain their confidence in the process; and (d) be accustomed to a secure environment [ ]. the comparison of fdi in different sectors of pakistan is shown in figure . it highlights that the power and energy sector of pakistan (pesp) has received a comparatively higher amount of fdi (about . percent), followed by the communication and financial business sectors ( . percent and . percent, respectively) in previous years. fdi in pesp has contributed significantly to the overall economic growth of the country over this period. the flows of fdi in the pesp and economic growth are shown in figure . both economic growth and fdi showed upward trends at the beginning of the period, while fdi continued in an upward trend until the year . in the year , pakistan tested its nuclear missiles to attain atomic power at the international level. as a result, pakistan faced different economic sanctions internationally and was confronted with the consequences in the form of a downward trend in fdi. sustainability , , x for peer review of to invest in power projects. the major aims of this policy are the following: a) to supply an adequate power production capacity with the minimum cost; b) to boost up, and make sure of, the exploitation of domestic resources; c) to provide a win–win situation to all key players and obtain their confidence in the process; and d) be accustomed to a secure environment [ ]. the comparison of fdi in different sectors of pakistan is shown in figure . it highlights that the power and energy sector of pakistan (pesp) has received a comparatively higher amount of fdi (about . percent), followed by the communication and financial business sectors ( . percent and . percent, respectively) in previous years. fdi in pesp has contributed significantly to the overall economic growth of the country over this period. the flows of fdi in the pesp and economic growth are shown in figure . both economic growth and fdi showed upward trends at the beginning of the period, while fdi continued in an upward trend until the year . in the year , pakistan tested its nuclear missiles to attain atomic power at the international level. as a result, pakistan faced different economic sanctions internationally and was confronted with the consequences in the form of a downward trend in fdi. the other major possible reasons for the downward trend in fdi were the political turmoil and the security situation in pakistan. in the year , pakistan faced a severe political crisis; consequently, the military took over the civilian government based on allegations of bad governance and other political issues. after the / terrorist attacks in the united states, pakistan participated in the war against terrorism. as a result, the security situation in pakistan became paralyzed, and investors avoided investing in pakistan. after a certain number of years, the relationship of pakistan with other countries, and its political and security situation, became better. thereafter, fdi showed an upward trend from to . from the year , fdi showed a mixed trend for the subsequent period. however, the economic growth of pakistan has followed an upward trend since the year . in recent years, pakistan has quietly succeeded in attracting foreign investors by offering tax incentives and providing a secure environment in the country. in the last five years, a number of new power projects were installed with the help of foreign investment [ ]. the major projects, which were installed during the period – , include genco-ii, guddu cc, quaid-e-azam (a solar plant), nandipur (a thermal plant), crest energy, chasnupp c- (nuclear), chasnupp c- (nuclear), united energy (wind), patrind (hydel), neelum jehlum (hydel), port qasim (coal), balloki (rlng), and tarbela t- unit- (hydel) [ ]. pakistan receives fdi from different countries, such as china, the united kingdom, and the united states. after starting the cpec project, the amount of chinese investment in pakistan has been significantly increased as compared to other countries [ ]. figure . sector-wise foreign direct investment for the period – figure . sector-wise foreign direct investment for the period – . sustainability , , x for peer review of figure . trends of foreign direct investment (fdi) (current u.s.$) in the power and energy sector of pakistan (pesp) and the gdp growth per capita (%). . theoretical and literature framework . . foreign direct investment (fdi) and economic growth the economic literature revolves around two main theories—modernization and dependency theories—to elaborate the linkage between fdi and economic growth [ ]. according to modernization theory, fdi helps to increase economic growth based on the significance of capital investment for achieving growth. fdi is the main source of technology transfer from developed countries to developing countries, which provides assistance to promote the domestic industry. usually, developing countries suffer from less developed infrastructure, political and economic instability due to insufficient resources. it is generally claimed that fdi could be helpful for the transfer of knowledge, marketing expertise, managerial skills, and different opportunities to access the market [ , ]. on the other side, according to the dependency school theory advocated by d o'hearn [ ], v bornschier [ ], and c stoneman [ ], fdi inflows can show a negative relationship with economic growth in the long-run. the basic reason was that the first world countries after world war ii became wealthier by mining different resources from third world countries. the developing countries were inadequately rewarded for their natural resources, which led to continuous poverty in those countries. the theorists found that capitalism is a basic cause for labor division at a global level. as a result, fdi can create hurdles for growth and increase the income inequality, which can negatively affect economic growth in the long-run. there could also be some other reasons for the negative linkage between fdi and economic growth. the most important reason is that foreign investment can reduce the production level of domestic firms through competition in the market. usually, foreign firms face lower marginal costs because of a firm-specific advantage, which provides them with the opportunity to captivate demand away from domestic firms. as a result, their cost is increased and production level decreased. there is also another reason that foreign firms may not be willing to spread firm-specific knowledge to domestic firms. as a result, the production of domestic firms could lead to an adverse situation due to backward technology and less-skilled workers [ ]. the debate about the relationship of fdi to economic growth has been extensively studied in the literature. however, the empirical results are varied across countries based on domestic human capital, infrastructure, and domestic policies to promote foreign investment and trade. some studies revealed the direct linkage of fdi with economic growth, while there are also many studies in the literature that have highlighted the inverse linkage of fdi with economic growth. studies that have specifically focused on fdi in the power and energy sector and its effect on economic growth are figure . trends of foreign direct investment (fdi) (current u.s.$) in the power and energy sector of pakistan (pesp) and the gdp growth per capita (%). sustainability , , of the other major possible reasons for the downward trend in fdi were the political turmoil and the security situation in pakistan. in the year , pakistan faced a severe political crisis; consequently, the military took over the civilian government based on allegations of bad governance and other political issues. after the / terrorist attacks in the united states, pakistan participated in the war against terrorism. as a result, the security situation in pakistan became paralyzed, and investors avoided investing in pakistan. after a certain number of years, the relationship of pakistan with other countries, and its political and security situation, became better. thereafter, fdi showed an upward trend from to . from the year , fdi showed a mixed trend for the subsequent period. however, the economic growth of pakistan has followed an upward trend since the year . in recent years, pakistan has quietly succeeded in attracting foreign investors by offering tax incentives and providing a secure environment in the country. in the last five years, a number of new power projects were installed with the help of foreign investment [ ]. the major projects, which were installed during the period – , include genco-ii, guddu cc, quaid-e-azam (a solar plant), nandipur (a thermal plant), crest energy, chasnupp c- (nuclear), chasnupp c- (nuclear), united energy (wind), patrind (hydel), neelum jehlum (hydel), port qasim (coal), balloki (rlng), and tarbela t- unit- (hydel) [ ]. pakistan receives fdi from different countries, such as china, the united kingdom, and the united states. after starting the cpec project, the amount of chinese investment in pakistan has been significantly increased as compared to other countries [ ]. . theoretical and literature framework . . foreign direct investment (fdi) and economic growth the economic literature revolves around two main theories—modernization and dependency theories—to elaborate the linkage between fdi and economic growth [ ]. according to modernization theory, fdi helps to increase economic growth based on the significance of capital investment for achieving growth. fdi is the main source of technology transfer from developed countries to developing countries, which provides assistance to promote the domestic industry. usually, developing countries suffer from less developed infrastructure, political and economic instability due to insufficient resources. it is generally claimed that fdi could be helpful for the transfer of knowledge, marketing expertise, managerial skills, and different opportunities to access the market [ , ]. on the other side, according to the dependency school theory advocated by d o’hearn [ ], v bornschier [ ], and c stoneman [ ], fdi inflows can show a negative relationship with economic growth in the long-run. the basic reason was that the first world countries after world war ii became wealthier by mining different resources from third world countries. the developing countries were inadequately rewarded for their natural resources, which led to continuous poverty in those countries. the theorists found that capitalism is a basic cause for labor division at a global level. as a result, fdi can create hurdles for growth and increase the income inequality, which can negatively affect economic growth in the long-run. there could also be some other reasons for the negative linkage between fdi and economic growth. the most important reason is that foreign investment can reduce the production level of domestic firms through competition in the market. usually, foreign firms face lower marginal costs because of a firm-specific advantage, which provides them with the opportunity to captivate demand away from domestic firms. as a result, their cost is increased and production level decreased. there is also another reason that foreign firms may not be willing to spread firm-specific knowledge to domestic firms. as a result, the production of domestic firms could lead to an adverse situation due to backward technology and less-skilled workers [ ]. the debate about the relationship of fdi to economic growth has been extensively studied in the literature. however, the empirical results are varied across countries based on domestic human capital, infrastructure, and domestic policies to promote foreign investment and trade. some studies revealed the direct linkage of fdi with economic growth, while there are also many studies in the literature sustainability , , of that have highlighted the inverse linkage of fdi with economic growth. studies that have specifically focused on fdi in the power and energy sector and its effect on economic growth are rarely available in the empirical literature. most of the prior studies have focused on the analysis of overall fdi and its relationship to economic growth along with different exogenous variables. the studies that focused on a single country to explore the nexus of fdi–economic growth include ma almfraji, mk almsafir, and y liu [ ]; c zhao and j du [ ]; m belloumi [ ]; f khatun and m ahamad [ ]; y hao, l zhu and m ye [ ]; js mah [ ]; ma fadhil and mk almsafir [ ]; c chakraborty and p nunnenkamp [ ]; s anwar and s sun [ ]; and cf tang and bw tan [ ]. the studies that selected multiple countries to analyze the nexus of fdi–economic growth include p gupta and a singh [ ]; s iamsiraroj [ ]; a omri and b kahouli [ ]; g agrawal [ ]; d herzer [ ]; s adams [ ]; p srinivasan, m kalaivani, and p ibrahim [ ]; m al-iriani [ ]; and sl gui-diby [ ]. for example, in the case of a single country to examine the nexus of fdi–economic growth, ma almfraji, mk almsafir, and y liu [ ] used time-series data for the period – by focusing on qatar as a sample. using vector auto-regression (var) and granger causality tests, the results of the study showed a significant effect of fdi inflows on economic growth in the long-run. c zhao and j du [ ] used a unit root test, the vector error correction model (vecm), the augmented-dickey–fuller (adf) test, and a co-integration test, and found a non-significant causal relationship between fdi and economic growth in the context of china for the period – . moreover, m belloumi [ ] applied the ardl bounds testing technique to study the relationship among trade openness, economic growth, and fdi by using data on tunisia for the period – . the findings of the study highlighted that there is no significant causality between economic growth and fdi. more specifically, f khatun and m ahamad [ ] could not find causality between fdi in the energy sector and economic growth in both the long-run and the short-run by using granger causality tests in case of bangladesh. in the case of multiple countries to analyze the nexus of fdi–economic growth, p gupta and a singh [ ] used a panel of data on brics countries for the period from to . using the ordinary least square (ols) technique, the johansen co-integration technique, and vecm, the results showed a causal relationship between fdi and economic growth in the context of china, brazil, and india. furthermore, the results also showed a short-run causal relationship between fdi and economic growth in the case of china. s iamsiraroj [ ] applied the fixed effect model and the generalized method of moments (gmm) model to a sample of countries for the time span – . the findings established the direct linkage of fdi with economic growth, while economic freedom, trade openness, and labor force, as the major determinants of fdi, were found to directly increase the income growth. moreover, a omri and b kahouli [ ] observed the relationship between fdi, energy consumption, and economic growth by constructing a panel dataset of countries for the period – . they divided the panel dataset more into three sub-panel datasets based on various income levels. using simultaneous equations with gmm, the results revealed bi-directional causality between fdi and economic growth in some countries. g agrawal [ ] employed vec granger causality and panel co-integration, and confirmed causality between fdi and economic growth by using a panel dataset on brics countries for the period – . table shows a summary of the main empirical studies about the fdi–economic growth nexus. sustainability , , of table . a summary of empirical studies on the foreign direct investment (fdi)–economic growth nexus. author (s) country sample period analysis technique findings single country studies y hao, l zhu and m ye [ ] china – the vector error correction model (vecm), fully modified ordinary least squares (fmols) bi-directional causality exists in the long-run js mah [ ] china – johansen co-integration test; granger causality test mixed results ma fadhil and mk almsafir [ ] malaysia – unit root tests, johansen co-integration test, hierarchical multiple regressions (hmr) significant positive relationship. c chakraborty and p nunnenkamp [ ] india – granger causality tests, johansen co-integration. bi-directional causality in the manufacturing sector. s anwar and s sun [ ] malaysia – generalized method of moments (gmm) significant positive relationship. cf tang and bw tan [ ] malaysia – unit root tests, johansen–juselius co-integration test, granger causality tests, ecm bi-directional causality multi-country studies d herzer [ ] developing countries – heterogeneous panel co-integration techniques on average: a negative effect in most of the countries s adams [ ] sub-saharan african countries – ordinary least square (ols) model, fixed effect model mixed results, positive results in case of ols p srinivasan, m kalaivani and p ibrahim [ ] saarc countries – johansen co-integration test, vecm, the impulse response function bi-directional causality exists in all selected countries except india m al-iriani [ ] bahrain, kuwait, oman, saudi arabia, and united arab emirates – granger causality test, panel co-integration test bi-directional causality sl gui-diby [ ] african countries – system generalized method of moment (sys-gmm) mixed results, – negative, – positive sustainability , , of . . energy consumption and economic growth in the economics literature, the debate about the nexus of energy consumption and economic growth was initiated by j kraft and a kraft [ ], and found the strongest evidence of a relationship between these variables by using data on the united states for the period – . afterward, many researchers examined causal relationships by using granger causality and tested four hypotheses: (a) the conservation hypothesis, (b) the neutrality hypothesis, (c) the feedback hypothesis, and (d) the growth hypothesis [ ]. neoclassical economists, such as er berndt [ ] and ef denison [ ], argued that energy is not the significant factor that causes economic growth based on the assumption that energy affects economic growth only in definite ways. on the contrary, ecological economists, such as ru ayres and i nair [ ], proposed a model in which they highlighted energy as the main factor of production based on the laws of thermodynamics. afterward, other researchers, such as cj cleveland, r costanza, ca hall, and r kaufmann [ ], also endorsed their model by finding significant evidence about the relationship between economic production and energy. furthermore, di stern [ ] also considered energy to be a vital factor in production. a fairly considerable number of studies have focused on the linkage of energy consumption with economic growth in many countries. the studies that focused on a single country to analyze the relationship between these variables include i ozturk and a acaravci [ ]; x-p zhang and x-m cheng [ ]; n bowden and je payne [ ]; m shahbaz, m zeshan, and t afza [ ]; as alshehry and m belloumi [ ]; w oh and k lee [ ]; m belloumi [ ]; g erdal, h erdal, and k esengün [ ]; f karanfil [ ]; w lise and k van montfort [ ]; k bakhsh, s rose, mf ali, n ahmad, and m shahbaz [ ]; and f khatun and m ahamad [ ]. the studies that concentrated on multiple countries to examine the energy consumption–economic growth nexus include vc govindaraju and cf tang [ ]; e lau, x-h chye, and c-k choong [ ]; rpp pradhan [ ]; n apergis and je payne [ ]; j asafu-adjaye [ ]; am masih and r masih [ ]; s noor and m siddiqi [ ]; c-c lee, c-p chang, and p-f chen [ ]; and b-n huang, mj hwang, and cw yang [ ]. for example, in the case of a single country to analyze the nexus of energy consumption and economic growth, i ozturk and a acaravci [ ] used the ardl technique and granger causality tests, and revealed a relationship among economic growth, employment rate, and energy consumption; however, while carbon emissions and energy consumption did not show causality with economic growth, the employment rate showed a causal relationship with economic growth in turkey for the sample period – . in addition, x-p zhang and x-m cheng [ ] used a multivariate model to analyze the relationship among carbon emissions, urban population, economic growth, and energy usage by selecting china as a sample for the period – . using co-integration and granger causality tests, the results highlighted the unidirectional causality between energy consumption and economic growth in the long-run. with the same view, m shahbaz, m zeshan, and t afza [ ] analyzed the relationship between renewable and non-renewable energies and economic growth by selecting pakistan as a sample for the period – . using ardl and granger causality tests, the results established a long-run causal relationship between energy consumption and economic growth. as alshehry and m belloumi [ ] examined the inter-relationship between economic activity, energy consumption, and energy price for saudi arabia by using data for the period – . using johansen multivariate co-integration tests and vecm, the results indicated that there is unidirectional causality running from energy consumption to economic growth in the long-run. in the case of multiple countries to examine the nexus of energy consumption and economic growth, vc govindaraju and cf tang [ ] employed the co-integration technique and vecm to analyze the relationship among co emissions, economic growth, and coal consumption in india and china. the results highlighted the causality among coal consumption, economic growth, and co emissions in the case of china, but not in india. the results confirmed a unidirectional causal relationship between co emissions and economic growth. e lau, x-h chye, and c-k choong [ ] sustainability , , of studied the causality between energy consumption and economic growth in the context of asian countries by using a panel of data for the time duration from to . the results of the study revealed that there is a long-run equilibrium in the selected countries. furthermore, energy consumption showed direct causality with economic growth both in the long-run and in the short-run. in addition, rpp pradhan [ ] explored the relationship of energy consumption, electricity consumption, and oil consumption with economic growth by selecting saarc countries as a sample for the time duration – . using the johansen co-integration technique and vecm, the results of the study highlighted unidirectional and bidirectional causality among the variables across the selected countries based on the type of energy consumption. n apergis and je payne [ ] applied the pedroni co-integration technique and vecm, and revealed unidirectional causality between economic growth and energy consumption by using data on six central american states for the period – . a summary of important empirical studies on the energy consumption–economic growth nexus is shown in table . sustainability , , of table . a summary of empirical studies on the energy consumption (ec)–economic growth nexus author (s) country sample period analysis technique findings single country studies w oh and k lee [ ] korea – granger causality and vecm unidirectional causality from ec to gdp m belloumi [ ] tunisia – granger causality and vecm bi-directional causality in the long-run; unidirectional causality in the short-run n bowden and je payne [ ] usa – toda–yamamoto unidirectional causality from ec to gdp g erdal, h erdal, and k esengün [ ] turkey – granger causality test, johansen co-integration test bi-directional causality f karanfil [ ] turkey – granger causality test, co-integration test unidirectional causality from gdp to ec w lise and k van montfort [ ] turkey – co-integration test unidirectional causality from gdp to ec multi-country studies j asafu-adjaye [ ] the philippines, thailand, india, indonesia – ; – granger causality test, co-integration test bi-directional causality in case of the philippines and thailand; unidirectional causality in case of india and indonesia am masih and r masih [ ] asian countries – granger causality test, co-integration test-ecm mixed results s noor and m siddiqi [ ] south asian countries – granger causality test, co-integration test-ecm mixed results c-c lee, c-p chang, and p-f chen [ ] oecd countries – panel co-integration-panel vec overall, bidirectional causality b-n huang, mj hwang, and cw yang [ ] countries with different income levels – gmm, vector auto-regression (var) model mixed results; unilateral causality in middle and high-income countries sustainability , , of . materials and methods this section contains the empirical models and techniques to find causality among the fdi in the power and energy sector, the energy consumption, and the economic growth of pakistan in both the long-run and the short-run. . . empirical approach and data collection the vector error correction model (vecm) and vector auto-regression (var) are the two prominent empirical models that are usually employed to identify granger causality among variables in such studies. var can be employed if the variables show integration at first order i( ) with no co-integration; otherwise, vecm can be applied in the case of co-integration with the same order of integration [ ]. hence, there is the prerequisite to detecting the order of integration of each variable before selecting vecm or var. we employed two unit roots tests, the augmented-dickey–fuller (adf) and philips–perron (pp) tests, to check the stationarity of each variable of the model. after identifying it, we employed the johansen co-integration test to analyze the long-run relationship among variables of the model. we employed vecm to detect causality among variables of the model in the long-run and short-run by following the approach adopted by the prior studies of m belloumi [ ], and g erdal, h erdal, and k esengün [ ]. furthermore, we employed the variance decomposition (vdc) test to have more consistent results by following the prior study conducted by s-d park [ ]. we used annual time-series data on fdi in the power and energy sector of pakistan, energy consumption, and gross domestic product (gdp) for the period – . the data were obtained from the state bank of pakistan (sbp) and world development indicators (wdi). . . empirical models to find the co-integration and causality among fdi in the power and energy sector, energy consumption, and gdp by using the johansen co-integration test and vecm, in line with a prior study [ ], this study ponders the following equations: ∆lnfd it = k ∑ i= α i ∆lnfd it−i + k ∑ j= α j ∆lngdpt−j + k ∑ l= α l ∆lnect−l + α ectt− + ∈ t + α ( ) ∆lnect = k ∑ i= α i ∆lnect−i + k ∑ j= α j ∆lnfd it−j + k ∑ l= α l ∆lngdpt−l + α ectt− + ∈ t + α ( ) ∆lngdpt = k ∑ i= α i ∆lngdpt−i + k ∑ j= α j ∆lnect−j + k ∑ l= α l ∆lnfd it−l + α ectt− + ∈ t + α ( ) in equations ( ) to ( ), fdi, ec, and gdp represent foreign direct investment, energy consumption, and gross domestic product, respectively, as a proxy for economic growth. all variables are set into their natural logarithmic form before the empirical analysis. it is helpful to interpret the series in growth terms after considering the first difference. ect stands for error correction term, which highlights the long-run effect in these variables; κs shows the lag count; and ∆s are the difference operators to detect short-run disturbances in these variables. furthermore, ∈ t, ∈ t, and ∈ t are the error terms. the causation of all endogenous variables of the model is interlinked with their lag values and the disequilibrium value of the preceding period. ects are usually used to capture the long-run effect in the model. if all of the variables of the model are out of equilibrium, then there is a requirement to adjust the dependent variable to minimize the error. this is generally known as the adjustment of equilibrium error [ ]. for the time-series data, it is required to check the stationarity for each series by using unit root tests. if the linear combinations of non-stationary series convert into their stationary form with the sustainability , , of same order of integration, the co-integration approach is applied [ ]. if the variables are co-integrated, vecm can be employed to find the granger causality among the variables. we adopted the same approach to find the causality among fdi in the pesp, energy consumption, and economic growth as depicted in figure . in this procedure, in equation ( ), gdp (ec) shows granger causality to fdi if the coefficients of lagged gdp (ec) or the coefficient of the lagged error correction term ectt− shows statistical significance. similarly, in equation ( ), fdi (gdp) shows granger causality to ec if the coefficients of lagged fdi (gdp) or the coefficient of the lagged error correction term ectt− shows statistical significance. likewise, in equation ( ), ec (fdi) shows granger causality to gdp if the coefficients of lagged ec (fdi) or the coefficient of the lagged error correction term ectt− shows statistical significance. sustainability , , x for peer review of integrated, vecm can be employed to find the granger causality among the variables. we adopted the same approach to find the causality among fdi in the pesp, energy consumption, and economic growth as depicted in figure . in this procedure, in equation ( ), gdp (ec) shows granger causality to fdi if the coefficients of lagged gdp (ec) or the coefficient of the lagged error correction term 𝐸𝐶𝑇𝑡− shows statistical significance. similarly, in equation ( ), fdi (gdp) shows granger causality to ec if the coefficients of lagged fdi (gdp) or the coefficient of the lagged error correction term 𝐸𝐶𝑇𝑡− shows statistical significance. likewise, in equation ( ), ec (fdi) shows granger causality to gdp if the coefficients of lagged ec (fdi) or the coefficient of the lagged error correction term 𝐸𝐶𝑇𝑡− shows statistical significance. figure . the nexus of fdi in the power and energy sector of pakistan (pesp), energy consumption, and economic growth. . empirical results . . descriptive statistics table highlights the descriptive statistics for each variable of the model. the average value of fdi is . with a standard deviation of . , which shows the higher variations among the values of fdi. the minimum value for fdi is with the maximum value of . . the average value of energy consumption is . with a standard deviation of . , which shows less variations among the values. the minimum value for energy consumption is . with a maximum value of . . the mean value of gdp is . with a standard deviation of . , which highlights the higher variations among the values of gdp. the minimum value of gdp is . with a maximum value of . . table . the descriptive statistics. . . unit root tests we checked the stationarity of each variable, including fdi, energy consumption, and gdp, by using the augmented-dickey–fuller (adf) and philips–perron (pp) unit root tests; the results are shown in tables and , respectively. the criteria to decide on a stationary or non-stationary series is dependent on the test statistics and probability values of the variables. the results of both tests— variables units mean median minimum maximum std. dev. foreign direct investment current usd in millions . . . . . energy consumption kg of oil equivalent (per capita) . . . . . gdp current usd in millions (per capita) . . . . . figure . the nexus of fdi in the power and energy sector of pakistan (pesp), energy consumption, and economic growth. . empirical results . . descriptive statistics table highlights the descriptive statistics for each variable of the model. the average value of fdi is . with a standard deviation of . , which shows the higher variations among the values of fdi. the minimum value for fdi is with the maximum value of . . the average value of energy consumption is . with a standard deviation of . , which shows less variations among the values. the minimum value for energy consumption is . with a maximum value of . . the mean value of gdp is . with a standard deviation of . , which highlights the higher variations among the values of gdp. the minimum value of gdp is . with a maximum value of . . table . the descriptive statistics. variables units mean median minimum maximum std. dev. foreign direct investment current usd in millions . . . . . energy consumption kg of oil equivalent (per capita) . . . . . gdp current usd in millions (per capita) . . . . . . . unit root tests we checked the stationarity of each variable, including fdi, energy consumption, and gdp, by using the augmented-dickey–fuller (adf) and philips–perron (pp) unit root tests; the results are shown in tables and , respectively. the criteria to decide on a stationary or non-stationary series is dependent on the test statistics and probability values of the variables. the results of both tests—adf and pp—highlight that all of the variables of the models are non-stationary at the level; however, these variables are converted to be stationary at the first difference with a i( ) order of integration. sustainability , , of table . the results of augmented-dickey–fuller (adf) unit root tests. variables augmented-dickey–fuller (adf) test order of integration constant constant and trend at level at st difference at level at st difference ∆lnfdi − . ( . ) − . ( . ) − . ( . ) − . ( . ) i( ) ∆lnec − . ( . ) − . ( . ) − . ( . ) − . ( . ) i( ) ∆lngdp . ( . ) − . ( . ) − . ( . ) − . ( . ) i( ) note: the corresponding probability values are given in parenthesis. table . the results of the philips–perron (pp) unit root tests. variables philips–perron (pp) test order of integration constant constant and trend at level at st difference at level at st difference ∆lnfdi − . ( . ) − . ( . ) − . ( . ) − . ( . ) i( ) ∆lnec − . ( . ) − . ( . ) − . ( . ) − . ( . ) i( ) ∆lngdp . ( . ) − . ( . ) − . ( . ) − . ( . ) i( ) note: the corresponding probability values are given in parenthesis. . . johansen co-integration and granger causality tests before applying the granger causality tests, the johansen co-integration technique was applied to analyze the co-integration among the variables of the model. the results of this approach are displayed in table . the number of lags is determined by following the akaike information criterion (aic). on the basis of trace and maximum eigenvalue tests, the hypothesis of ‘none’ co-integrating equations in the model is rejected at the % significance level. hence, it can be extracted that fdi, energy consumption, and gdp have at least one co-integration equation, which highlights the long-run integration among the variables of the model. table . the results of the johansen co-integration test. number of co-integration equations eigenvalue trace test max. eigenvalue test λtrace % critical value prob. λmax % critical value prob. none ** . . . . . . . at most . . . . . . . note: ** specifies % significance level to reject the hypothesis. after finding the co-integration among the variables, the vecm was applied to ascertain the sources and specify the directions of causality among fdi in the pesp, energy consumption, and gdp in the long-run and the short-run. the results are shown in table . the decision criteria are dependent on the test statistics, which comprise the values of t-tests and wald tests. the wald tests were employed to analyze the causality among variables in the form of a group. the results of wald test- do not show mutual granger causality of energy consumption and fdi to gdp, χ = . sustainability , , of ( . ). furthermore, the results of wald test- confirm the mutual granger causality of gdp and fdi to energy consumption, χ = . ( . ). moreover, the results of wald test- do not highlight the mutual granger causality of gdp and energy consumption to fdi, χ = . ( . ). table . the results of the granger causality test (vecm). dependent variables sources of causation short-run relationship long-run relationship short-run granger causal relationship long-run ∆lnfdi ∆lnec ∆lngdp ectt−i ∆lnfdi - . ( . ) . ( . ) . ( . ) no causality no ∆lnec . ( . ) - . ** ( . ) − . * ( . ) gdp causes ec yes ∆lngdp . ( . ) . *** ( . ) - . ( . ) ec causes gdp no note: *, **, and *** represent the %, %, and % significance levels, respectively. the corresponding probability values are given in parenthesis. the results highlight that both gdp and energy consumption do not have a causal relationship with fdi in both the short-run and the long-run. in contrast, positive bi-directional causality is found to run from gdp to energy consumption and from energy consumption to gdp in the short-run at the % and % significance levels, respectively. this predicts that an increase in gdp leads to an increase in energy consumption and vice versa. it can be extracted that the economic growth of pakistan is dependent on energy consumption, as it plays a vital role in creating economic activity in the country. our results are consistent with the findings of the previous studies conducted by g erdal, h erdal, and k esengün [ ], j asafu-adjaye [ ], c-c lee, c-p chang, and p-f chen [ ], c-c lee and c-p chang [ ], s paul and rn bhattacharya [ ], s-h yoo [ ], and j asafu-adjaye [ ] to find the causality between economic growth and energy consumption in the context of different countries. bi-directional causality between gdp and energy consumption is inevitable for pakistan, which is a rapidly growing developing country. bi-directional causality has also been found in the case of many emerging countries, such as turkey and india. indeed, the economic growth helps to accelerate the energy consumption at the beginning. on the other side, technological development caused by economic growth helps to bring energy sources to the country, which stimulate the economic growth. because pakistan is highly dependent on external energy sources, any hurdle in the way of energy supply could disrupt the energy consumption. as a result, the overall economic development of the country could be adversely affected. furthermore, the coefficient of ectt− is found to be insignificant, which indicates that a long-run equilibrium relationship does not exist from gdp and energy consumption to fdi in equation ( ). the coefficient of ectt− is found to be significant at the % level of significance in equation ( ); so, it confirms the presence of a negative long-run equilibrium relationship from fdi and gdp to energy consumption. this result is similar to the findings of the previous study conducted by f khatun and m ahamad [ ], which found a negative long-run equilibrium relationship from fdi and gdp to energy consumption in the context of bangladesh. as we have mentioned earlier, pakistan is facing the problem of circular debt and receiving a large amount of fdi, which consists mainly of loans. if pakistan could not pay back these loans in the future, then the economy of pakistan is likely to be negatively affected by yet more accumulated debt. eventually, the energy consumption could be adversely affected in the long-run. the coefficient of ectt− is found to be insignificant, which highlights that a long-run equilibrium relationship does not exist from fdi and energy consumption to gdp in equation ( ). in addition, table highlights the results of the variance decomposition test. the results demonstrate that gdp shows a strong self-explanatory power in the short-run, while it is decreased to sustainability , , of % in the long-run. the other two variables, fdi and energy consumption, do not show shocks to the gdp in the short-run. moreover, % of fdi is explained by shocks to the fdi in the short-run. this self-explanatory power of fdi is decreased to % in the long-run. in the short-run, gdp accounts for % of fdi, while fdi is affected by the energy consumption in the long-run. furthermore, energy consumption shows a self-explanatory power of % and % in the short-run and long-run, respectively. in the short-run, . % of fdi is explained by shocks to energy consumption and increases over time, followed by gdp. these findings suggest that energy consumption is highly affected by economic growth in the short-run. table . the results of the variance decomposition test. variance decomposition of lngdp variance decomposition of lnfdi variance decomposition of lnec period lngdp lnfdi lnec period lngdp lnfdi lnec period lngdp lnfdi lnec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . conclusions and policy implications this study highlighted the present situation of the pesp and empirically analyzed the causality among the fdi in the power and energy sector, the energy consumption, and the economic growth of pakistan for the period – . we employed adf and pp unit root tests to check the stationarity of each variable. the results of these tests highlight that all of the variables of the models are non-stationary at the level; however, these variables are converted to be stationary at the first difference with a i( ) order of integration. after converting the variables into their stationary form, we employed the johansen co-integration technique and a granger causality test (vecm) to find the causality among variables in the long-run and short-run. moreover, we employed the variance decomposition (vdc) test to yield more consistent results. the sector-wise comparison of fdi reveals that the pesp has received a relatively higher amount of fdi than other sectors of the economy in recent years. furthermore, the trends in energy production and energy usage reveal a substantial gap in previous years. the empirical results of the study confirmed the presence of a positive bi-directional causal relationship between energy consumption and economic growth. it refutes the assumption of neoclassical theory that energy is unbiased to growth. it also indicates that the declining trend in energy consumption could be harmful to economic growth and vice versa. therefore, policy-makers should formulate policies to ensure the availability of energy and efficient energy usage for the production of goods and services. furthermore, the results of the study highlight that there is a negative long-run equilibrium relationship between fdi and gdp with energy consumption. presently, the power and energy sector of pakistan (pesp) is facing a severe problem of circular debt while also receiving loan-based investments to meet its needs. if pakistan could not pay back its loans in the future, the economy of pakistan is likely to be negatively affected by yet more accumulated debt. ultimately, the energy consumption could be adversely affected. we suggest that the gop should attain the minimum debt level and discourage loan-based investments. they should find alternative investment sources (without loans) and also formulate policies to increase the tax collection and export level. moreover, the gop should make serious efforts to deal with the major constraints on the power and energy sector, such as intense reliance on oil and gas, de-rated capacity, circular debt, energy security and threats, and bad governance. it should adopt alternative, and less costly, energy sources sustainability , , of to decrease the intense reliance on oil and gas. the de-rated capacity of energy units could be better by investing more funds to overhaul the energy units. the problem of circular debt could be fixed by real investment (without loans), effective management, and control over the cash flows. it is necessary to take effective security measures in remote areas to exercise control over energy security problems. better governance, by hiring productive staff and controlling the corruption factor, could be beneficial to improve the performance of pakistan’s power and energy sector. author contributions: conceptualized, drafted methodology, data collected & analyzed, and wrote-original manuscript, r.l.; reviewed and supervised this study, l.l. funding: the apc was funded by nanjing agricultural university, china. acknowledgments: the authors would like to acknowledge the financial support provided by nanjing agricultural university, china. furthermore, we acknowledge the comments and suggestions given by anonymous reviewers that have significantly improved the quality of our work, and the overall support of nadeem khan from nanjing agricultural university, china to complete this study. conflicts of interest: the authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. abbreviations adf augmented-dickey fuller aic akaike information criterion ardl autoregressive distributed lag cpec china pakistan economic corridor cppa central power purchase agency discos distribution companies ect error correction term fdi foreign direct investment gdp gross domestic product gencos generation companies gmm generalized method of moments gop government of pakistan ipps independent power producers kesc karachi electric supply corporation lng liquefied natural gas ntdc national transmission & dispatch company ogdcl oil and gas development company limited paec pakistan atomic energy commission parco pak arab refinery limited pesp power and energy sector of pakistan phpl power holding private limited pol pakistan oilfields limited pp philips-perron ppl pakistan petroleum limited prl pakistan refinery limited pso pakistan state oil saarc south asian association for regional cooperation sngpl sui northern gas pipelines limited ssgcl sui southern gas company limited var vector auto regression vecm vector error correction model wapda pakistan water and power development authority sustainability , , of references . latief, r.; 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[crossref] © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . /j.apenergy. . . http://dx.doi.org/ . /mas.v n p http://dx.doi.org/ . /j.eneco. . . http://dx.doi.org/ . /s - ( ) - http://dx.doi.org/ . / - ( ) - http://dx.doi.org/ . /j.eneco. . . http://dx.doi.org/ . /j.ecolecon. . . http://dx.doi.org/ . /j. - . .mp .x http://dx.doi.org/ . /j.eneco. . . http://dx.doi.org/ . /j.eneco. . . http://dx.doi.org/ . /j.enpol. . . http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	introduction 	overview of pakistan’s power and energy sector 	the structure of pakistan’s power and energy sector 	suppliers of primary energy 	power generators and power distributors 	end consumers 	major constraints on pakistan’s power and energy sector 	intense reliance on oil/gas 	de-rated capacity 	circular debt 	energy security and threats 	bad governance 	energy production, import, and consumption 	the role of fdi in pakistan’s power and energy sector 	theoretical and literature framework 	foreign direct investment (fdi) and economic growth 	energy consumption and economic growth 	materials and methods 	empirical approach and data collection 	empirical models 	empirical results 	descriptive statistics 	unit root tests 	johansen co-integration and granger causality tests 	conclusions and policy implications 	references .ijact_표지 international journal of advanced culture technology vol. no. - ( ) http://dx.doi.org/ . /ijact. . . . potential of agricultural residues for small biomass power generation in thailand thakrit panklib siam technology college, bangkok, thailand abstract the demand for energy in thailand has been continually increasing as the economic and social country grows. approximately % of thailand’s primary energy is imported, mostly petroleum products. in thailand’s total energy consumption was , ktoe and the net price of energy imported was up to , billion baht which is equivalent to . % of gdp at the current price. the energy consumption or energy demand has been growing at an annual compounded growth rate of . % and the peak electric power demand and electricity consumption was recorded at , mw and , gwh and grew at a rate of . % and . % per annum during the period from to . the gross agriculture production in was recorded at . mt which represents agriculture residue for energy at . mt, which is equivalent to energy potential of about . pj or , ktoe an increase in average of . % and . % per year respectively. the agricultural residues can converted to , gwh/year or , mw of power capacity. so, if government sector plan to install small biomass gasification for electricity generation kw for community. the residue agricultural is available for , plants nationwide. the small biomass power generation for electricity generation not only to reduce the energy imports, it also makes the job and income for people in rural areas as well. this paper’s aim is to report the energy situation in thailand and has studied main agricultural products with high residue energy potential namely sugarcane, paddy, oil palm, cassava, and maize appropriate for small electricity production. these agricultural products can be found planted in many rural areas throughout thailand. finally, discuss the situation, methods and policies which the government uses to promote small private power producers supplying electricity into the grid. keywords: biomass, agricultural residues, energy potential, gasification . introduction the total energy consumption in thailand has been continually increasing. most of the energy thailand uses is imported such as petroleum products. although thailand can provide some of its own energy ijact - - manuscript received: dec. , / revised: dec. , / accepted: jan. , corresponding author: drthakrit@gmail.com tel, + - - - fax: + - - - siam technology college, bangkok, thailand international journal of advanced culture technology vol. no. - ( ) recourses such as natural gas and crude oil, the domestic energy recourses are not sufficient because of the increasing demand and the limitation of these energy resources. over % of the total energy consumption of the country was absorbed by three main economic sectors namely the power, transport, and manufacturing sectors. electric power is one of the major input factors in economic development. the process requires a lot of energy. when fuel prices increase the power price is increased accordingly. use of alternative energy or renewable energy in the country is essential. thailand is an agricultural country. agriculture is a nationwide distribution. at present, biomass can be used to generate electricity from small electricity generation facilities. it is an effective way of eliminating agricultural waste and another way to reduce fossil fuel use. now there are many supports from the government for small electricity producers such as the small power producer and very small power producer programs (spp and vspp) that allows selling the power to the grid under long term contracts, providing an “adder” on top of the normal tariff, soft loans, investment subsidies, etc. currently the demand for electricity is increasing continuously but large power plants are difficult to build because of the local people’s opposition. while a small biomass power plant uses less space for installation, the life cycle of the biomass is relatively short and the process is not complicated, the local people can manage them by themselves. small biomass power plants are another way to solve the energy crisis in future. is important to reduce energy imports and reduce greenhouse gas emissions to the atmosphere as well. this paper’s aim is describing the energy situation in thailand, the potential of biomass energy from agricultural residue appropriate for small electricity production, and the current policies of the government for promotion of power production for small power producers, which use biomass and renewable energy as the fuel to produce the electricity. . energy and electricity situation in thailand approximately % of thailand’s primary energy is imported, mostly petroleum products. thailand can provide some of its own energy resources, such as natural gas, crude oil from the gulf of thailand and lignite from the northern part of country, but these domestic energy resources are not sufficient because of the demand for energy has been continually increasing and the limitation of its energy resources. in thailand’s total primary energy consumption was , ktoe [ ]. energy consumption is one of the major input factors in economic development. to support economic growth and meet energy requirements in the future, alternative energy resources are needed. year e n e rg y c o n s u m p ti o n ( k to e ) x x x x x energy production energy import figure . energy consumption in thailand potential of agricultural residues for small biomass power generation in thailand figure shows the energy consumption in thailand during the period from to . the energy consumption or energy demand has been growing at an annual compounded growth rate of . %. the energy consumption is the sum of energy import and energy production which has been growing at an annual compounded growth rate of . % and . % per annum respectively from to . over % of the total energy consumption of the country was absorbed by three main economic sectors namely the power, transport, and manufacturing sectors. the economic condition and the world oil prices have pushed thailand’s net energy import to , billion baht in equivalent to . % of gdp at current price [ ] as shown in figure . year v a lu e o f e n e rg y i m p o rt ( b il li o n b a h t) e n e rg y i m p o ry / g d p ( % ) value of energy import % energy impory / gdp figure . value of energy import and percent of energy import/gdp year e le c tr ic it y c o n s u m p ti o n ( g w h ) x x x x x x x x x p e a k d e m a n d ( m w ) gwh mw figure . peak electric demand and consumption electric power is one of the major input factors in economic development. figure shows the electricity consumption and peak electric power demand in thailand from to . in the peak electric power demand and electricity consumption was recorded at , mw and , gwh and peak electric power demand and electric consumption grew at a rate of . % and . % per annum from to respectively. electric consumption will be continued increasing occurring in the power demand. it was observed that the electricity consumption and peak electric power demand decreased sharply because of the economic crisis during and . electricity forecasting has become one of the most important aspects international journal of advanced culture technology vol. no. - ( ) of electricity utility planning and it’s very important today that we are planning to use alternative energy or renewable energy for the country’s future. . potential of biomass energy from agricutural residual thailand is one of the world leaders in agricultural production. biomass resources, especially agricultural residues, are abundant in the country. sajjakulnukit et al. [ ] studied biomass residues from main agricultural residues which possess energy potential. in the country’s total agricultural waste was million tons. the study further estimated an amount of million tons of biomass residues, which is equivalent to about x mj of energy, was unused. another independent study by ec-asean cogen program estimated that energy potential from main agricultural residues, namely bagasse, rice husk, palm oil wastes, and wood residues, was , gwh/yr or mw of power capacity [ ]. there are several other agricultural residues in the country that can also be used for energy. this paper has studied main agricultural products with high residue energy potential namely sugarcane, paddy, oil palm, cassava, and maize, planted in rural areas, and appropriate for small electricity producer. the energy potential estimation was performed based on residue product ratio (rpr) and as received calorific values as shown in table i. table . rpr, calorific values and factor of agricultural residues product residue rpr surplus lhv (mj/kg) residue energy availability factor (as received) weight factor potential factor sugarcane bagasse . . . . . top & trash . . . paddy husk . . . . . straw (top) . . . oil palm empty bunches . . . . . fiber . . . shell . . . frond . . . male bunches . . . cassava stalk . . . . . maize corn cob . . . . . *sources: bhattachaya et al. ( ); dedp ( , , ); black and veatch ( ). residue production ratio is the ratio of the amount of residue generated to the total amount of agricultural product produce and surplus availability factor is the ratio of surplus (presently wasted) amount to the amount of residue generated. most calorific values or low heating value (lhv) were obtained from the tests conducted in the laboratories of the department of energy development and promotion (dedp) of thailand. the residue weight factor and energy potential factor are used to convert gross weight of agricultural products to residue weight and energy potential, the example in case of sugarcane, residue weight factor = (rprbagasse x surplus availability factorbagasse) + (rprtop & trash x surplus availability factortop & trash) and energy potential factor = (rprbagasse x surplus availability factorbagasse x lhvbagasse ) + (rprtop & trash x surplus availability factortop & trash x lhvtop & trash). in the gross agriculture production namely paddy, maize, cassava, sugarcane and oil palm was recorded at . mt. the residues available for energy and energy potential of agricultural residues are potential of agricultural residues for small biomass power generation in thailand . mt and . pj or , ktoe respectively. figure shows the trend of each product in thailand. the agricultural production of paddy, maize, cassava, sugarcane and oil palm increases in average of . %, . %, . %, . %, . % and . % per year respectively and the total of production increases in average of % per year. table ii shows each type of agricultural production, table iii shows a residue available for energy, table iv shows energy potential and table v shows the summary of estimate agricultural residues and energy potential from to . the total of agricultural residues available for energy and energy potential are increases in average of . % and . % per year as shows in figure . the information from status of biomass potential in [ ], there are many types of biomass with more than % non-exploited. so, there are main agricultural residues about . mt. the non-exploited residue available for energy and energy potential are . mt and . pj. in case of small electricity generation, it is assumed that the average lhv is mj/kg. at full generation rate use in a gasifier/gas engine generator, giving an overall efficiency of conversion to electricity of about %, this takes no account of the potentially useful heat available from the gasifier/gas engine [ ]. the agricultural residues can converted to , gwh/year or , mw of power capacity. so, if the thailand government is having planned to install small biomass gasification for electricity generation kw for sub-district administrative organization (sao). the residue agricultural is available for , plants nationwide. year p ro d u c ti o n ( m t) paddy maize cassava sugarcane oil palm figure . the trend of each agricultural product in thailand in to year e n e rg y p o te n tia l (p j) r e si d u e a va ila b le fo r e n e rg y (m t) pj mt figure . thailand agricultural residues and energy potential in to international journal of advanced culture technology vol. no. - ( ) table . production of agriculture in to year production (mt) total paddy maize cassava sugarcane oil palm (mt) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . table . residues available for energy in to year residue available for energy (mt) total paddy maize cassava sugarcane oil palm (mt) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . potential of agricultural residues for small biomass power generation in thailand table . energy potential in to year energy potential (pj) total paddy maize cassava sugarcane oil palm (pj) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . table . summary of agricultural residues and energy potential in to year residue available energy potential for energy (mt) (pj) (ktoe) . . , . . . , . . . , . . . , . . . , . . . , . . . , . . . , . . . , . . . , . . . , . . . , . . . , . . . , . . . , . . . , . . . , . . . , . . . , . . . , . international journal of advanced culture technology vol. no. - ( ) . conclusions due to the current energy crisis, energy electricity demand and fuel prices continually increasing every year and the government’s issuance of policies to promote energy efficiency and renewable energy, it can be seen that biomass-based power generation seems to be quite possible in both the technological aspects and the potential of biomass. however, for sustainable achievement, the thai government does not only create confident mechanisms but also continually encourages the ipps and spps with power purchase agreements, incentive investments, as well as research for new pilot plants. small electricity production from biomass agricultural residue is one solution to solve the domestic demand for the electricity in the future. it is feasible because small biomass power plants can be installed throughout the country, the local people can manage them by themselves and agricultural residues are plentiful in rural areas. in addition it would considerably decrease the burning of our forests and the disposal of agricultural residue saving the environment from so and nox emissions emitted into the atmosphere. although energy policies adopted by the government are in the right direction, the pace of implementation is slow. it is very important for the government to disseminate information through public campaign to educate the public about alternative energy. . references [ ] bhattachaya, s. c., shrestha, r. m., and ngamkajurnvivat, s. . potential of biomass residue availability: the case of thailand. energy sources : – . [ ] black & veatch. . thailand biomass-based power generation and cogeneration: small rural industries (progress report). bangkok, thailand: black & veatch. [ ] center for agricultural information (cai). . agricultural statistics of thailand crop year . bangkok, thailand: center for agricultural information. [ ] department of energy development and promotion (dedp). . the study of behavior and patterns of energy use in plantation: summary report. bangkok, thailand: department of energy development and promotion. [ ] department of energy development and promotion (dedp). . report on coconut residue investigation. bangkok, thailand: department of energy development and promotion. [ ] department of energy development and promotion (dedp). . report on the investigation of residues from palm oil industry. bangkok, thailand: department of energy development and promotion. [ ] department of energy development and promotion (dedp). . thailand alternative energy situation . bangkok, thailand: department of energy development and promotion. [ ] ec-asean cogen program of asian institute of technology. . evaluation of conditions for electricity production based on biomass. bangkok, thailand. [ ] energy policy and planning office (eppo). . energy for environment foundation, biomass resources management for alternative energy in macro level. bangkok, thailand: the energy policy and planning office. [ ] energy policy and planning office (eppo). . thailand energy statistics . bangkok, thailand: energy policy and planning office, ministry of energy. potential of agricultural residues for small biomass power generation in thailand [ ] mckendry, p. . energy production from biomass (part ): overview of biomass. bioresour. technol. : – . [ ] ministry of energy. . thailand’s energy conservation and renewable energy development program – . bangkok, thailand: ministry of energy. [ ] ministry of energy. . alternative energy, cogeneration and distributed generation: crucial strategy for sustainability of thailand’s energy sector, october –february . bangkok, thailand: ministry of energy. [ ] sajjakulnukit, b., yingyuad, r., maneekhao, v., and pongnarintasut, v. . assessment of sustainable national biomass resource potential for thailand. bangkok, thailand: department of energy development and promotion (dedp). asian journal of applied science and engineering issn - x(p); - (e) asian business consortium | ajase ● dec ● vol ● issue page evaluation of wind energy potential alongside motorways of pakistan abid a. khan , , zahid mehmood , asim shahzad , khalid a. chughtai , awais javed institute of space technology, pakistan national university of science and technology, pakistan article info abstract volume number / issue doi: . /ajase/ received: oct , accepted: dec , revised: dec , published: jan , e-mail for correspondence: khanabid @hotmail.com presently world in general and pakistan in particular is facing energy crisis despite the fact that pakistan is blessed with natural resources required for its generation. there is a need to resolve the crises as they are directly affecting all spheres of life. the government is trying to explore economical renewable energy resources. one such renewable energy resource available in abundance is wind. different potential sites for harnessing wind energy in pakistan have already been identified by researchers. this paper aims at identifying the additional wind energy generation sites alongside the motorways due to natural wind and vehicular generated vortices due to heavy traffic. it aims at experimentally measuring the wind data and then calculating the available power potential at selected sites utilizing measured data. the most suitable sites for installation of the wind farm have also been identified and proposed with the estimate of total power potential. key words: renewable energy, wind energy, experimental measurements, vehicular vortices, natural energy resource source of support: nil, conflict of interest: declared how to cite: khan aa, mehmood z, shahzad a, chughtai ka and javed a. . evaluation of wind energy potential alongside motorways of pakistan asian journal of applied science and engineering, , - . this article is is licensed under a creative commons attribution-noncommercial . international license. attribution-noncommercial (cc by-nc) license lets others remix, tweak, and build upon work non-commercially, and although the new works must also acknowledge & be non-commercial. introduction resently pakistan is facing severe electricity crisis of its history. recent statistics show a shortfall of above mw between energy supply and demand. if the situation is not addressed, the energy supply and demand gap would even widen in the future. kessides analyzed the current energy demand and supply gap for pakistan and also forecasted the future energy state under do nothing scenario(kessides ). the study is depicted in figure . currently, conventional means of power generation in pakistan are p http://creativecommons.org/licenses/by-nc/ . / asian journal of applied science and engineering issn - x(p); - (e) asian business consortium | ajase ● dec ● vol ● issue page being utilized which is mainly oil based generation. total generation of electricity by different sector in pakistan is presented in figure (shah and bhatti ). power generation through conventional means has many disadvantages associated, out of which the most important is cost of power generation. since, pakistan does not have sufficient oil reserves, therefore, to meet oil requirement for power generation, pakistan imports much of its oil from other countries. the fossil fuels being the highest contributor of world’s primary energy; its reserves are diminishing rapidly(muneer and asif ). the increasing prices of the oil mad this option difficult and in turn increased the power generation cost. pakistan meets about . % of its annual primary commercial energy needs from imported fuel by spending about us$ billion (harijan et al. ). another disadvantage associated with oil based power generation is air pollution. renewable energy power generation sources instead reduce the carbon emissions considerably. islam et al. has studied the reductions in carbon emissions by various energy sources as shown in figure (islam, mekhilef, and saidur ). the trend of energy generation and its potential world over presented by different researchers (Şahin ; kaldellis and zafirakis ; sun, huang, and wu ) shows that there is a need for an earlier move over from conventional to renewable energies that are naturally available in abundance and are capable to meet the current and projected global energy needs. pakistan is fortunate to have a significant potential of such renewable energies. farooq et al. studied the available and expected installed potential of renewable energies in pakistan and same has been shown in table (farooq and kumar ). amer et al. has also studied the renewable energy generation options from perspectives of technical, economic, social, environmental and political aspects for pakistan(amer and daim ). amongst the renewable energy resources, pakistan has a potential of wind energy harvesting. past, present and future utilization of wind energy has been elaborated by bhutto et al. (bhutto, bazmi, and zahedi ). they also discussed the efforts needed in this sector to effectively use this economical source. isolated efforts are being made for utilization of wind energy both at govt and commercial level. mirza et al. summarized the wind energy development activities being pursued in pakistan(mirza et al. ), while researchers (mirza, khan, and memon ; ullah, chaudhry, and chipperfield ; sheikh , ; aman et al. ; nasir, raza, and abidi ) have identified potential sites in pakistan for wind energy generations. the researchers in their work only focused on potential of sindh and baluchistan and did not consider the wind potential in locations at other provinces of the countries. moreover, the wind potentials along the motorways were also neglected altogether. importance of wind energy potential to convert it into other forms of energies has also been recognized at global level. the installed capacity of wind energy in the top countries around the world is shown in figure (ilkılıç, aydın, and behçet ; erdogdu ; yaniktepe, savrun, and koroglu ; lew ; li, hubacek, and siu ). wind energy due to its environmental friendly nature and competitive cost is making its way globally, and various countries have defined their wind energy policies (saidur et al. ; dincer ). it is estimated that coal-fired power stations typically emit around – g of co for every unit (kwh) of electricity they produce. therefore, each unit of electricity produced by wind energy avoids polluting the environment by an equivalent amount of emissions (Şahin ). while talking in terms of cost, it is observed that the energy generated by a wind mill could be twice as efficient as that obtained from a diesel generator (bhutto, bazmi, and zahedi ). wind phenomena along highways and motorways has been studied at global level (rao et al. ; kalthoff et al. ; alonso- asian journal of applied science and engineering issn - x(p); - (e) asian business consortium | ajase ● dec ● vol ● issue page estébanez et al. ; musa, osman, and hamat ) but same has neither been studied nor its potential was evaluated to enhance energy sector in pakistan. the focus of this study is to evaluate the wind energy potential along motorways. advantages due to use of such technology along motorways are not only limited to traffic noise suppression, but it also includes cost and environmental benefits. pedersen et al. has shown that road traffic noise can provide a significant masking of wind farm noise(pedersen et al. ). wind potential along motorways currently, there are two major motorway sectors in pakistan i.e., m- and m- . m- ; starts from peshawar and ends at islamabad, while m- ; starts from islamabad and ends at lahore. wind map of pakistan shown in figure was utilized to identify the potential sites for wind speed measurements on motorways. based upon the wind map, four potential sites, burhan interchange, katti hills corridor, ghazi barotha and chakri corridors were selected for measurements and evaluation of the wind potential. wind speeds were measured at these sites using anemometer with capability to measure from . - m/s. around measurements were taken at each selected location over a period of twelve months to calculate average wind speed over the year. chakri corridor had the highest wind potential with an average wind speed of . m/s, while ghazi barotha canal corridor had the lowest wind potential with an average wind speed of . m/s. the wind speed at katti hill corridor and burhan interchange were measured as m/s and . m/s respectively. the recorded readings are tabulated in table . in addition to natural wind potential, vehicular induced wind turbulence and increase in the wind speed due to vehicular turbulence were also measured. the vehicle passing rate on m- was vehicles per minute and that on m- was vehicles per minute with heavier vehicles using outer lanes on both sides. the effect of traffic disturbance on the natural wind speed was also observed which was significant with heavier traffic movement in the external lanes. the vehicular movement had a positive effect of . to . m/s for light traffic vehicles and from . to . m/s for heavy traffic vehicles. based upon the data collected through measurements at different sites on motorway, theoretical power potential of these sites was calculated using analytical equations. the result of this analysis is the basis for selection of sites suitable for installation of windmills along the motorways. the reference turbine used for these calculations has m diameter. following equation was used for theoretical power calculations: ( ) the procedure followed for calculation of power is illustrated as follows: (a) the distance in meters from the center of the central shaft to one of the blades was measured and then the rotor swept area was calculated. (b) the wind speed of the site was measured using a wind anemometer, and the altitude of that site was measured using altimeter. (c) the air density of the site was determined using atmospheric tables. the power potential with a single wind turbine of the type specified earlier at selected sites is tabulated in table . chakri corridor had a highest potential of watts per turbine, while ghazi barotha corridor had a lowest potential of . watts per turbine. the power potential at katti hill corridor and burhan interchange were . and . watts per turbine respectively. p= / cp a v asian journal of applied science and engineering issn - x(p); - (e) asian business consortium | ajase ● dec ● vol ● issue page conclusion electricity production through wind is one of the economical sources of electricity, and if seriously explored, it can be useful in improving the energy crisis in pakistan. based on the calculated and measured data, it is relatively safe to say that chakri wind corridor is one of the suitable sites along the motorway for generation of electricity through wind mills. chakri wind corridor is spread over an area of kilometers. keeping the safe distance between the two turbines to avoid flow disturbance, wind turbines can be installed on each side. so a total of wind turbines on both sides of the road at a safer distance of km corridor can be installed. these wind turbines can produce an average of . mw of electricity that can subsequently be added to the national grid or used for localized purposes. these wind turbines can generate substantial revenue annually. references alonso-estébanez, a., p. pascual-muñoz, c. yagüe, r. laina, and d. castro-fresno. . field experimental study of traffic-induced turbulence on highways. atmospheric environment ( ): - . aman, m. m., g. b. jasmon, a. ghufran, a. h. a. bakar, and h. mokhlis. . investigating possible wind energy potential to meet the power shortage in karachi. renewable and sustainable energy reviews ( ): - . amer, muhammad, and tugrul u. daim. . selection of renewable energy technologies for a developing county: a case of pakistan. energy for sustainable development ( ): - . bhutto, abdul waheed, aqeel ahmed bazmi, and gholamreza zahedi. . greener energy: issues and challenges for pakistan—wind power prospective. renewable and sustainable energy reviews ( ): - . dincer, furkan. . the analysis on wind energy electricity generation status, potential and policies in the world. renewable and sustainable energy reviews ( ): - . erdogdu, erkan. . on the wind energy in turkey. renewable and sustainable energy reviews ( – ): - . farooq, muhammad khalid, and s. kumar. . an assessment of renewable energy potential for electricity generation in pakistan. renewable and sustainable energy reviews ( ): - . harijan, khanji, mohammad a. uqaili, mujeebuddin memon, and umar k. mirza. . assessment of centralized grid connected wind power cost in coastal area of pakistan. renewable energy ( ): - . ilkılıç, cumali, hüseyin aydın, and rasim behçet. . the current status of wind energy in turkey and in the world. energy policy ( ): - . islam, m. r., s. mekhilef, and r. saidur. . progress and recent trends of wind energy technology. renewable and sustainable energy reviews ( ): - . kaldellis, j. k., and d. p. zafirakis. . . - trends, prospects, and r&amp;d directions in wind turbine technology. in comprehensive renewable energy, edited by s. editor-in-chief: ali. oxford: elsevier. kalthoff, n., d. bäumer, u. corsmeier, m. kohler, and b. vogel. . vehicle-induced turbulence near a motorway. atmospheric environment ( ): - . kessides, ioannis n. . chaos in power: pakistan's electricity crisis. energy policy ( ): - . lew, debra j. . alternatives to coal and candles: wind power in china. energy policy ( ): - . li, x., k. hubacek, and y. l. siu. . wind power in china – dream or reality? energy ( ): - . mirza, irfan afzal, nasim a. khan, and naeem memon. . development of benchmark wind speed for gharo and jhimpir, pakistan. renewable energy ( ): - . mirza, umar k., nasir ahmad, tariq majeed, and khanji harijan. . wind energy development in pakistan. renewable and sustainable energy reviews ( ): - . muneer, t., and m. asif. . prospects for secure and sustainable electricity supply for pakistan. renewable and sustainable energy reviews ( ): - . asian journal of applied science and engineering issn - x(p); - (e) asian business consortium | ajase ● dec ● vol ● issue page musa, nor, kahar osman, and ab malik a. hamat. . renewable energy from induced airflow generated by cruising ground vehicles in tandem using rans. energy procedia ( ): - . nasir, s. m., s. m. raza, and s. b. h. abidi. . wind energy in balochistan (pakistan). renewable energy ( – ): - . pedersen, eja, frits van den berg, roel bakker, and jelte bouma. . can road traffic mask sound from wind turbines? response to wind turbine sound at different levels of road traffic sound. energy policy ( ): - . rao, k. s., r. l. gunter, j. r. white, and r. p. hosker. . turbulence and dispersion modeling near highways. atmospheric environment ( ): - . Şahin, ahmet duran. . progress and recent trends in wind energy. progress in energy and combustion science ( ): - . saidur, r., m. r. islam, n. a. rahim, and k. h. solangi. . a review on global wind energy policy. renewable and sustainable energy reviews ( ): - . shah, sifat, and m k l bhatti. . crisis of electrical energy in pakistan and future guidelines for policy makers. international journal of basic and applied sciences ( ). sheikh, munawar a. . renewable energy resource potential in pakistan. renewable and sustainable energy reviews ( ): - . repeated author. . energy and renewable energy scenario of pakistan. renewable and sustainable energy reviews ( ): - . sun, xiaojing, diangui huang, and guoqing wu. . the current state of offshore wind energy technology development. energy ( ): - . ullah, irfan, qamar-uz-zaman chaudhry, and andrew j. chipperfield. . an evaluation of wind energy potential at kati bandar, pakistan. renewable and sustainable energy reviews ( ): - . yaniktepe, b., m. m. savrun, and t. koroglu. . current status of wind energy and wind energy policy in turkey. energy conversion and management ( ). figure : energy supply and demand gap pakistan [ ] figure : power generation in pakistan by different sectors [ ] asian journal of applied science and engineering issn - x(p); - (e) asian business consortium | ajase ● dec ● vol ● issue page figure : contribution of co emissions reductions in various power sectors [ ] figure : country wise installed capacity of wind energy [ ] figure : wind map of pakistan [ ] asian journal of applied science and engineering issn - x(p); - (e) asian business consortium | ajase ● dec ● vol ● issue page figure : power potential of various sites along motorway table : available and expected renewable installed potential till (mw) [ ] table : recorded wind speeds along motorways table : calculated wind potential along motorways -- – ajase!!! “speedy publication service, online archives, paperless, web-based peer review 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crisis due to lapse of conventional sources and expected to meet the large demand in power all over the world especially in developing country like india. among the renewable resources, wind & solar are the most popular ones because of their abundance, ease of accessibility and which can be easily converted to the electricity. this paper presents the design and analysis of a hybrid solar-wind system for domestic purpose in the remote areas of the country where continuous power supply from central grid is a problem index terms: boost converter, hybrid system, off-grid region photo voltaic, sepic converter, wind energy i. introduction energy is one of the most important factors for the economic welfare of any nation. in case of developing countries, the increasing energy demand needs huge amount of investments to be met, which is of critical importance now. the continuous increase in human population in the world has created several problems regarding the need of power and increase in toxic gases. one of them is global warming, occurring due to the abundance of co available in the atmosphere, which is a toxic gas. to reduce this emission into the atmosphere, alternative sources of energy must be used. for the last twenty years, solar energy and wind energy are the alternate and renewable resources that are available in plenty. in hybrid system, wind turbine and photovoltaic cells, offer greater reliability than using them separately because the demand is not entirely based on one resource. for example, on a stormy day when solar energy is low there is likely enough wind energy available to compensate the lack of solar energy. even in the absence of one source the other source can compensate without uninterrupted power supply. in remote areas, where the grid connected power system does not exist, the standalone system can be used to satisfy the power demand. ii. proposed hybrid system fig shows the block diagram of solar wind hybrid system which is very useful in remote places and residential complexes which are far away from power plants and which need long transmission lines.the pv module is connected to revised manuscript received on july , . rohini govindaraju,professor, department of electrical and electronics engineering, jerusalem college of engineering, chennai, india saritha natesandepartment of electrical and electronics engineering, jerusalem college of engineering, chennai, india lavanya, ganesh, abishagcynthiadepartment of electrical and electronics engineering, jerusalem college of engineering, chennai, india the dc-dc converter unit to step-up or step down the voltage levels to match the common dc link provided in the system. fig. . block diagram of hybrid power system the wind turbine is followed by a pmsg generator, which generates an ac voltage which is further rectified to dc voltage through a rectifier unit. this dc voltage is now fed to the dc-dc converter circuit in order to regulate the output dc voltage obtained from the turbine and generator setup in accordance with the common dc link. the input for the inverter unit is taken from the dc link and the output obtained (ac voltage through inverter) and is given as supply to the load. iii. modelling of system components the standalone hybrid generation system includes a wind generation module and a solar module feeding power to a common dc bus through necessary power electronic converters. although a hybrid wind-solar electric system demands a higher technology, but the hybrid systems are the best option for a significant improvement in terms of production and efficiency. a. pv module solar panels are the types to convert solar power into the electrical power. solar panels can convert the energy by two ways directly or heat the water from the induced energy. pv (photo-voltaic) cells are semiconductor structures as in the computer technologies. fig. . shows the simulation diagram of pv panel. sun light is absorbed with this material and electrons are emitting from this materials. solar power is converted into the electric power. hybrid standalone system for rural electrification rohini govindaraju, saritha natesan, lavanya, ganesh, abishag cynthia hybrid standalone system for rural electrification published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s fig. . simulation diagram of pv panel the output power of a solar cell is given by: ppv =vpv *ipv ( ) where, ipv - output current of solar cell (a) vpv - solar cell operating voltage (v) ppv - output power of solar cell (w). b. wind genration module the wind power generation module basically consists of a wind turbine with the consideration that the blades are rigidly fixed to the turbine. as a result, the pitch angle of the blades also remain fixed. the wind energy which strikes these blades, produces a mechanical torque which further drives a permanent magnet synchronous generator (pmsg) to produce an electrical output and can be modeled as follows. the wind turbine output power relating to wind velocity can be represented as: pm = . ρ ar cp ( λ, β) vω ( ) where vω - wind velocity, β - blade pitch angle. cp - power coefficient, ar - swept area of rotor blades, λ - tip speed ratio ρ - air density fig . . simulation diagram of wind turbine the coefficient of power cp can be expressed as a function of tip-speed ratio λ and pitch angle of turbine blade β, where the tip-speed ratio (tsr) λ is expressed by the equation λ = r ωr/ vω ( ) where ωr- rotational speed of the rotor r - the radius of the rotor blades c. pmsg model the equivalent circuit of the pmsg in the d-q synchronous rotating reference frame is used for dynamic modeling of the pmsg.the d-q synchronous rotating reference frame voltages are referred with vd,vq, rs is the resistance on stator side, ld, lq are the inductances of the generator on the d and q axis, is the electrical rotating speed of the generator. the electromagnetic torque of pmsg is defined by the following model equation, te = . p (lds-lis) idiq + iqψf ( ) where p is the number of generator pole pairs. d. three phase rectifier the ac output from the pmsg is converted to dc using a three-phase uncontrolled rectifier whose output voltage vrec is given by vrec = . vm ( ) ignoring the diode losses in the diode rectifier, the output power from the converter remains unchanged and is utilized only for rectification process. e. dc-dc boost converter the dc-dc boost converter controls the variable input voltage from pmsg-rectifier unit to a fixed dc output voltage. this converter controls the magnitude of output such that it satisfies the requirement of the inverter unit. the equation relating the input and output voltage of this dcdc converter is given by, vdc = vin( -d) ( ) where d is the duty ratio. fig. . simulation diagram of boost converter f. dc-dc sepic converter the sepic (single-ended-primary-inductor converter) is a type of dc to dc converter that allows the electrical potentialat its output to be greater thanor less than at its input. the equation relating the input and output voltage of this dc-dc converter is given by, vout = d*vin/( -d) ( ) where d is the duty ratio. international journal of recent technology and engineering (ijrte) issn: – , volume- , issue- s , july published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s fig. . simulation diagram of sepic converter g. p-i controller p-i controller is mainly used to eliminate the steady state error resulting from p controller. however, in terms of the speed of the response and overall stability of the system, it has a negative impact. this controller is mostly used in areas where speed of the system is not an issue. since p-i controller has no ability to predict the future errors of the system it cannot decrease the rise time and eliminate the oscillations. if applied, any amount of i guarantees set point overshoot. fig. . block diagram of pi controller h. inverter the dc voltage at the dc bus is then converted to ac with the help of a sinusoidal pulse width modulated (spwm) inverter. if ton is the turn-on time of the switch, the rms output voltage can be determined by: vo = vs [ ∑ ( ton/t) ]^( / ) ( ) the pulses are produced by amplitude modulation and the modulation index is defined as: ma = vcon/vc ( ) where, vcon - peak magnitude of control signal (modulating sine wave) vc - peak magnitude of carrier signal (triangular signal) fig. . simulation diagram of three phase inverter iv. simulation results . wind turbine module the wind turbine is simulated in simulink using the above modelling equations; where the inputs to the model are wind speed m/s; pitch angle , rotor diameter, air density and turbine speed. fig. . output of wind turbine fig. . output of wind turbine with rectifier . pv module the pv module produces v.the i-v characteristics for different solar irradiation values are given by. the output voltage of pv array is given by fig. . output of solar panel d. boost and sepic with pi controller p-i controller is mainly used to eliminate the steady state error resulting from p controller. however, in terms of the speed of the response and overall stability of the system, it has a negative impact. the output of boost converter with pi controller is given by fig. . output of boost converter with pi controller the output of the boost hybrid standalone system for rural electrification published by: blue eyes intelligence engineering & sciences publication retrieval number: b s / ©beiesp doi: . /ijrte.b . s converter v is given as the input for sepic converter and the output of the sepic converter with pi controller is given fig. . output of sepic converter with pi controller e. load with three phase inverter the inverter converts dc to ac source , which is connected to the three phase r load. the r load which is connected may be incandescent lamp , electrical heaters etc. in resistive load the current is in phase with the voltage, the current rises immediately to its steady-state value , without first rising to a higher value. it can have a little inrush current. fig. shows the simulation diagram of inverter with r load fig. simulation diagram of inverter with r load vi. hybrid system a hybrid arrangement of combining the power harnessed from both the wind and the sun can be a much more reliable and realistic power source. fig. simulation diagram of hybrid system hybrid systems are usually built for design of systems with lowest possible cost and also with maximum reliability. fig. . output of hybrid system vii. conclusion in this paper, the modelled hybrid power generation system is devised to achieve the task of increasing the power extraction over a wide range of wind velocities and solar intensities and provide an uninterruptable power to meet the demand. also, standalone renewable energy production can be a better alternative to conventional energy production particularly in rural areas and remote locations, where access to electricity is difficult. pv array and wind turbine are simulated with its associated converters are designed and simulated using matlab. references [ ] p. thounthong and s. rael, “the benefits of hybridization,” ieee ind. electron. mag., vol. , no. , pp. – , sep. . [ ] s. m. muyeen, r. takahashi, t. murata, and j. tamura, “integration of an energy capacitor system with a variable-speed wind generator,” ieee trans. energy convers., vol. , no. , pp. – , sep. . [ ] l. wang and d. j. lee and w. j. lee and z. chen, ’’analysis of a novel autonomous marine hybrid power generation/energy storage system with a high-voltage direct current link”, journal of power source, volume , issue , pages – , december . [ ] x.yingcheng and t. nengling, “review of contribution to frequency control through variable speed wind turbine”, renewable energy, volume , issue , pages - , june [ ] d. j. lee and l. wang, ‘’small-signal stability analysis of an autonomous hybrid renewable energy power generation/energy storage system part i: time-domain simulations”, ieee transaction on energy conversion, vol. , no. , march . [ ] h. m. k. al-masri and m. ehsani, "impact of wind turbine modeling on a hybrid renewable energy system," ieee industry applications society annual meeting, portland, or, , pp. - . [ ] j. plaza castillo, c. dazamafiolis, e. coral escobar, a. garcia barrientos and r. villafuerte segura, "design, construction and implementation of a low cost solar-wind hybrid energy system," in ieee latin america transactions, vol. , no. , pp. - , oct. . [ ] f. guérin, d. lefebvre, a. b. mboup, j. y. parédé, e. lemains and p. a. s. ndiaye, "hybrid modeling for performance evaluation of multisource renewable energy systems," in ieee transactions on automation science and engineering, vol. , no. , pp. - , july . [ ] g. rohini and v. jamuna, “pll based energy efficient pv system with fuzzy logic based power tracker for smart grid applications,” the scientific world journal, vol. , article id , pages, [ ]a. jenifer., n. r. newlin, g. rohini. and v. jamuna., "development of matlab simulink model for photovoltaic arrays," international conference on computing, electronics and electrical technologies (icceet), kumaracoil, , pp. - acute respiratory infection unveiling cpt ii deficiency international journal of molecular sciences case report acute respiratory infection unveiling cpt ii deficiency nicolas blah , , bénédicte sudrié-arnaud , stéphanie torre , stéphane marret , , soumeya bekri , and abdellah tebani ,* department of metabolic biochemistry, rouen university hospital, rouen, france; nicolas.blah@etu.univ-rouen.fr (n.b.); b.sudrie-arnaud@chu-rouen.fr (b.s.-a.); soumeya.bekri@chu-rouen.fr (s.b.) department of internal medicine, rouen university hospital, rouen, france department of neonatal pediatrics, intensive care and neuropediatrics, rouen university hospital, rouen, france; stephanie.torre@chu-rouen.fr (s.t.); stephane.marret@chu-rouen.fr (s.m.) normandie université, unirouen, chu rouen, inserm u , rouen, france * correspondence: abdellah.tebani@chu-rouen.fr; tel.: + - - - - - received: august ; accepted: september ; published: september ���������� ������� abstract: carnitine palmitoyl transferase (cpt ii) is involved in long-chain fatty-acid mitochondrial transport. three clinical phenotypes of cpt ii deficiency have been described: lethal neonatal onset, infantile severe form, and the late onset more common muscular form. the muscular form of cpt ii deficiency is characterized by pain crises and rhabdomyolysis triggered by energy-dependent factors. this form has been described as a benign condition; however, the acute crises are insidious and thus, pose a risk of death. we report a -year-old female child with an acute pulmonary infection and a concomitant rhabdomyolysis. the acylcarnitine profile was consistent with cpt ii deficiency and a molecular study allowed the identification of the common missense variant (nm_ . : c. c>t – p. ser leu) at the homozygous state. the striking difference between the initial cause and the decompensation severity prompted us to consider other diagnoses. deciphering the symptoms linked to cpt ii deficiency among those of the initial decompensation results in initiating a timely a targeted therapy. keywords: carnitine palmitoyl transferase; cpt ii; rhabdomyolysis; acute infection; energy failure; beta oxidation . introduction carnitine palmitoyl transferase (cpt ii) deficiency belongs to the mitochondrial beta-oxidation disorder family. this autosomal recessive disease is due to a defective transport of long-chain fatty acids from the inter-membrane space to the mitochondrial matrix where beta oxidation occurs (figure ). the clinical manifestations are related to a decreased beta-oxidation rate and the subsequent decrease in atp concentration in the cells which rely on fatty acid oxidation for their energy production (muscle, heart) [ ]. three clinical phenotypes have been described: lethal neonatal onset with multisystemic alterations [ ], infantile severe form which affects mainly the central nervous system (cns), liver, heart and muscles [ ], and the late-onset mild muscular form [ ]. patients with the muscular form present with recurrent muscular pain episodes with rhabdomyolysis that can possibly lead to renal failure, respiratory insufficiency, and arrhythmia. several mechanisms underlie the subsequent cell damages (i) the absence of ketone body production and (ii) the inhibition of krebs-cycle enzymes by non-metabolized long chain fatty acids with a consecutive myocardial toxicity. rhabdomyolysis results from skeletal muscle damage and the alteration of plasma membrane integrity with a subsequent release of the intracellular biomolecules into the bloodstream (cpk, myoglobin). the main int. j. mol. sci. , , ; doi: . /ijms www.mdpi.com/journal/ijms http://www.mdpi.com/journal/ijms http://www.mdpi.com https://orcid.org/ - - - http://www.mdpi.com/ - / / / ?type=check_update&version= http://dx.doi.org/ . /ijms http://www.mdpi.com/journal/ijms int. j. mol. sci. , , of pathophysiological mechanism underlying rhabdomyolysis is related to calcium homeostasis. indeed, a decrease in atp production and fragilization of the plasma membrane lead to an increased level of cellular free ionized calcium. this increase alters cellular functions, such as skeletal muscle cell contractility and mitochondrial metabolism and, ultimately, leads to cell death [ , ]. muscular cpt ii deficiency may remain asymptomatic and an acute crisis may be triggered upon an energy crisis, excessive energy expenditure, or a shortage of energy supply such as infection, prolonged exercise, or fasting. muscular cpt ii deficiency is often misdiagnosed and specific preventive and treatment managements are postponed. the diagnosis is delayed due to the unspecific clinical features, which may be masked by the clinical effects of the triggering factor such as infection. besides, the biological diagnosis is tricky; an acylcarnitine profile is analyzed in routine practice and a cpt ii deficiency acylcarnitine profile is informative with elevated concentrations of long-chain acylcarnitines, c , c , c : . however, this profile is often normal between the acute crises. cpt ii enzyme activity assessment is reliable but a molecular study is usually conducted directly [ , , ]. in this study, the case of a child with a cpt ii deficiency is reported to emphasize that raising the awareness of intermittent presentations of cpt ii deficiency is challenging. int. j. mol. sci. , , x for peer review of (cpk, myoglobin). the main pathophysiological mechanism underlying rhabdomyolysis is related to calcium homeostasis. indeed, a decrease in atp production and fragilization of the plasma membrane lead to an increased level of cellular free ionized calcium. this increase alters cellular functions, such as skeletal muscle cell contractility and mitochondrial metabolism and, ultimately, leads to cell death [ , ]. muscular cpt ii deficiency may remain asymptomatic and an acute crisis may be triggered upon an energy crisis, excessive energy expenditure, or a shortage of energy supply such as infection, prolonged exercise, or fasting. muscular cpt ii deficiency is often misdiagnosed and specific preventive and treatment managements are postponed. the diagnosis is delayed due to the unspecific clinical features, which may be masked by the clinical effects of the triggering factor such as infection. besides, the biological diagnosis is tricky; an acylcarnitine profile is analyzed in routine practice and a cpt ii deficiency acylcarnitine profile is informative with elevated concentrations of long-chain acylcarnitines, c , c , c : . however, this profile is often normal between the acute crises. cpt ii enzyme activity assessment is reliable but a molecular study is usually conducted directly [ , , ]. in this study, the case of a child with a cpt ii deficiency is reported to emphasize that raising the awareness of intermittent presentations of cpt ii deficiency is challenging. figure . mitochondrial transport of long-chain fatty acids. while medium- and short-chain fatty acids enter the mitochondria freely, long-chain fatty acids require carnitine-dependent transport to cross the mitochondrial membranes. in the cytosol, long chain fatty acids are converted to acyl-coa by the acyl-coa synthase. the carnitine palmitoyltransferase i (cpt i) located in the outer mitochondrial membrane catalyzes the conversion of acyl-coa into acylcarnitines. the latter crosses the outer membrane and goes through the inner membrane via a transporter named translocase. carnitine palmitoyltransferase ii (cpt ii), which is located in the inner mitochondrial membrane, allows for the conversion of acylcarnitines into acyl-coas and free carnitine. carnitine exits the mitochondria via the translocase and thus, is recycled to form other acylcarnitines. acyl-coas are directed toward the beta-oxidation process. . clinical history and background a -year-old female child was hospitalized in the pediatric department for dyspnea and fever ( . °c). she had a normal psychomotor development with no particular medical history. a week figure . mitochondrial transport of long-chain fatty acids. while medium- and short-chain fatty acids enter the mitochondria freely, long-chain fatty acids require carnitine-dependent transport to cross the mitochondrial membranes. in the cytosol, long chain fatty acids are converted to acyl-coa by the acyl-coa synthase. the carnitine palmitoyltransferase i (cpt i) located in the outer mitochondrial membrane catalyzes the conversion of acyl-coa into acylcarnitines. the latter crosses the outer membrane and goes through the inner membrane via a transporter named translocase. carnitine palmitoyltransferase ii (cpt ii), which is located in the inner mitochondrial membrane, allows for the conversion of acylcarnitines into acyl-coas and free carnitine. carnitine exits the mitochondria via the translocase and thus, is recycled to form other acylcarnitines. acyl-coas are directed toward the beta-oxidation process. . clinical history and background a -year-old female child was hospitalized in the pediatric department for dyspnea and fever ( . ◦c). she had a normal psychomotor development with no particular medical history. a week before, she was seen by a general practitioner for fever, bronchial congestion, odynophagia, cough and rhinitis. a chest x-ray showed a pulmonary right basal opacity and the patient was referred to pediatric int. j. mol. sci. , , of emergency service. at presentation, she was polypneic and suffered from muscular pain with a fast worsening of the general state. rsv (respiratory syncitial virus) type b has been identified as the cause of the respiratory infection. besides, biological investigations showed a major inflammatory syndrome (c-reactive protein: mg/l—n < ) an elevation of transaminases (asat: ui/l, alat: ui/l—n: – ) with a major increase of creatine phosphokinase ( , ui/l n: – ) and were consistent with an acute rhabdomyolysis. further metabolic evaluations included urinary organic acid chromatography, a blood acylcarnitine profile, ketone bodies and lactate/pyruvate assessments. the increased long-chain acylcarnitine concentrations (c : . µmol/l—n < . ; c : . µmol/l—n < . ; c : : . µmol/l—n < . ), the elevation of the calculated (c : + c : )/c ratio . (n: . – . ) and the decrease in the free carnitine concentration ( µmol/l—n > ) on the acylcarnitine profile (figure ) were suggestive of cpt ii deficiency. the other metabolic investigations were normal. raising the hypothesis of cptii deficiency helped to manage the acute phase by considering lipid avoidance and glucose infusion. the hospitalization was marked by the progressive regression of dyspnea, muscular pain and partial regression of rhabdomyolysis biological features. int. j. mol. sci. , , x for peer review of figure . acylcarnitine profile using an lc-ms/ms method. (a) control; (b) patient. peaks represent butylated esters of acylcarnitines acquired by precursor ion scanning of m/z in positive ion mode. derivatized samples were injected into a sciex qtrap mass spectrometer (sciex, framingham, ma, usa) using an autosampler. peaks corresponding to isotopically labeled internal standards are denoted by an asterisk. . discussion cpt ii deficiency has been described as a benign condition. however, the acute crises are insidious and may occur during or after several hours of the at-risk situation and may pose a risk of death [ , ]. the disease severity may be due to (i) the associated rhabdomyolysis and its potential consequences; the nature of the infectious agent is not of importance, the energy expenditure due to this infection triggers the decompensation and the energetic imbalance leading to rhabdomyolysis (ii) the toxicity of the long chain fatty-acids and acylcarnitines on mitochondrial metabolisms [ ] (iii) the decrease of free carnitine, which is necessary for long-chain fatty acid beta-oxidation notably in cardiac cells (iv) the consequences of the infectious episode. the striking difference between the initial cause and the decompensation severity should prompt us to consider other diagnoses such as energy failure. deciphering the symptoms linked to cpt ii deficiency among those of the initial decompensation results in initiating a timely and targeted therapy. during the acute crisis, the treatment consists of glucose infusion and lipid avoidance. long- term treatment is mainly based on an adapted diet: avoidance of fasting, high-carbohydrate and low- fat diet, supplemented with medium chain triglycerides and carnitine. besides, some prevention rules should be observed: protection from infections, stress, prolonged exercise, fever, and prohibition of figure . acylcarnitine profile using an lc-ms/ms method. (a) control; (b) patient. peaks represent butylated esters of acylcarnitines acquired by precursor ion scanning of m/z in positive ion mode. derivatized samples were injected into a sciex qtrap mass spectrometer (sciex, framingham, ma, usa) using an autosampler. peaks corresponding to isotopically labeled internal standards are denoted by an asterisk. int. j. mol. sci. , , of secondarily, a molecular study of the cpt ii gene allowed for the identification of the common missense variant (nm_ . : c. c>t – p. ser leu) in the homozygous state, which is reported as a frequent variant in the muscular form of cpt ii deficiency. this variant was found in a heterozygous state in both the unaffected parents and in a homozygous state in her younger sister. . discussion cpt ii deficiency has been described as a benign condition. however, the acute crises are insidious and may occur during or after several hours of the at-risk situation and may pose a risk of death [ , ]. the disease severity may be due to (i) the associated rhabdomyolysis and its potential consequences; the nature of the infectious agent is not of importance, the energy expenditure due to this infection triggers the decompensation and the energetic imbalance leading to rhabdomyolysis (ii) the toxicity of the long chain fatty-acids and acylcarnitines on mitochondrial metabolisms [ ] (iii) the decrease of free carnitine, which is necessary for long-chain fatty acid beta-oxidation notably in cardiac cells (iv) the consequences of the infectious episode. the striking difference between the initial cause and the decompensation severity should prompt us to consider other diagnoses such as energy failure. deciphering the symptoms linked to cpt ii deficiency among those of the initial decompensation results in initiating a timely and targeted therapy. during the acute crisis, the treatment consists of glucose infusion and lipid avoidance. long-term treatment is mainly based on an adapted diet: avoidance of fasting, high-carbohydrate and low-fat diet, supplemented with medium chain triglycerides and carnitine. besides, some prevention rules should be observed: protection from infections, stress, prolonged exercise, fever, and prohibition of some medications (e.g., valproic acid). the medium-chain fatty acid triheptanoin has been described to be effective in the late-onset cpt ii deficiency [ , ]. for our patient and her younger sister, medium chain triglycerides and carnitine supplementation have been initiated and to date the evolution is favorable. during the acute phase, characteristic acylcarnitine profile and clinical features guided the diagnosis and enabled the early implementation of a specific treatment. therefore, recognition of cpt ii deficiency through appropriate investigations, despite confounding factors, could be helpful to prevent dramatic consequences and subsequent triggering situations. author contributions: n.b. drafted the manuscript and drew the figures. b.s.-a. collected the clinical data. s.t. and s.m. followed-up with the patient and collected the clinical data. s.b. critically edited and revised the manuscript. a.t. supervised the study and edited and revised the manuscript. all the authors approved the final version of the manuscript. funding: this research received no external funding. acknowledgments: the authors are grateful to carine tardivel-pilon and thomas plichet (rouen university hospital) for their technical assistance. conflicts of interest: the authors declare no conflicts of interest. abbreviations cpt carnitine palmitoyl transferase cpt ii carnitine palmitoyl transferase lc-ms/ms liquid chromatography coupled to tandem mass spectrometry references . joshi, p.r.; deschauer, m.; zierz, s. carnitine palmitoyltransferase ii (cpt ii) deficiency: genotype-phenotype analysis of patients. j. neurol. sci. , , – . [crossref] [pubmed] . du, s.h.; zhang, f.; yu, y.g.; chen, c.x.; wang, h.j.; li, d.r. sudden infant death from neonate carnitine palmitoyl transferase ii deficiency. forensic sci. int. , , e –e . [crossref] [pubmed] http://dx.doi.org/ . /j.jns. . . http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /j.forsciint. . . http://www.ncbi.nlm.nih.gov/pubmed/ int. j. mol. sci. , , of . meir, k.; fellig, y.; meiner, v.; korman, s.h.; shaag, a.; nadjari, m.; soffer, d.; ariel, i. severe infantile carnitine palmitoyltransferase ii deficiency in -week fetal sibs. pediatr. dev. pathol. , , – . [crossref] [pubmed] . lehmann, d.; motlagh, l.; robaa, d.; zierz, s. muscle carnitine palmitoyltransferase ii deficiency: a review of enzymatic controversy and clinical features. int. j. mol. sci. , , . [crossref] [pubmed] . giannoglou, g.d.; chatzizisis, y.s.; misirli, g. the syndrome of rhabdomyolysis: pathophysiology and diagnosis. eur. j. intern. med. , , – . [crossref] [pubmed] . zutt, r.; van der kooi, a.j.; linthorst, g.e.; wanders, r.j.; de visser, m. rhabdomyolysis: review of the literature. neuromuscul. disord. nmd , , – . [crossref] [pubmed] . deschauer, m.; wieser, t.; zierz, s. muscle carnitine palmitoyltransferase ii deficiency: clinical and molecular genetic features and diagnostic aspects. arch. neurol. , , – . [crossref] [pubmed] . fanin, m.; anichini, a.; cassandrini, d.; fiorillo, c.; scapolan, s.; minetti, c.; cassanello, m.; donati, m.a.; siciliano, g.; d’amico, a.; et al. allelic and phenotypic heterogeneity in italian patients with the muscle form of cpt-ii deficiency. clin. genet. , , – . [crossref] [pubmed] . labarthe, f.; gelinas, r.; des rosiers, c. medium-chain fatty acids as metabolic therapy in cardiac disease. cardiovasc. drugs ther. , , – . [crossref] [pubmed] . gillingham, m.b.; heitner, s.b.; martin, j.; rose, s.; goldstein, a.; el-gharbawy, a.h.; deward, s.; lasarev, m.r.; pollaro, j.; delany, j.p.; et al. triheptanoin versus trioctanoin for long-chain fatty acid oxidation disorders: a double blinded, randomized controlled trial. j. inherit. metab. dis. , , – . [crossref] [pubmed] © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . / - - . http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /ijms http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /j.ejim. . . http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /j.nmd. . . http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /archneur. . . http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /j. - . . .x http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /s - - - http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /s - - - http://www.ncbi.nlm.nih.gov/pubmed/ http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	introduction 	clinical history and background 	discussion 	references microsoft word - biores_ _ _ _hubbe_toovaluabletoburn_edito .doc editorial ncsu.edu/bioresources hubbe ( ). “editorial: too valuable to burn?” bioresources ( ), - . are lignocellulosic resources too valuable to burn? martin a. hubbe lignocellulosic matter often can be counted as a renewable resource, since it is produced by photosynthesis. but there are limits to how much biomass our society can use in a sustainable manner. people can debate whether or not it makes sense to use a substantial portion of lignocellulosic materials as a source of liquid fuel. this essay gives a qualified affirmative answer to the question in its title. however, combustion of lignocellulosic resources can be considered as wasteful and uneconomical, in the long run, if it is inefficient, if it fails to displace the combustion of fossil fuels, or if it displaces a higher-end use, for which there are available customers. in particular, it seems unlikely that combustion of fuels derived from lignocellulosic biomass can, by itself, solve problems that stem from society’s excessive thirst for motor fuels. keywords: biofuels; lignocellulosic resources; alternative uses contact information: department of forest biomaterials science and engineering; college of natural resources; north carolina state university; campus box ; raleigh, nc - ; hubbe@ncsu.edu high-value uses of lignocellulosic resources the pages of this journal, bioresources, include many research articles that describe how lignocellulosic resources can become converted to relatively high-value products and structures. other articles describe ways to extract the energy content from lignocellulosic biomass – for instance in the form of liquid fuels for powering motor vehicles. at some point, these latter uses tend to compete for a limited, though renewable set of resources. in this context the question is worth asking, whether lignocellulosic resources, in general or specifically, may be too valuable to burn. to be specific, some higher-value uses of lignocellulosic resources discussed in these pages have included the following: biores. ( ): paper products, oriented strand board: biores. ( ): particle-board, composites, dialysis membranes; biores. ( ): textile fibers, adsorption of toxic heavy metals; biores. ( ): activated carbon, nanofibers, solid wood properties, component of an adhesive; biores. ( ): plant growth enhancement, nanocomposite; biores. ( ): sorption of heavy metal ions, treated solid wood, etc., etc. “dumping” of low-valued lignocellulosic resources presently a large proportion of the available cellulosic resources are “dumped.” either they are landfilled, burned on site, or thrown into piles not suitable for composting. editorial ncsu.edu/bioresources hubbe ( ). “editorial: too valuable to burn?” bioresources ( ), - . examples include the landfilling of paper products, piles of brush cast aside in the forest (by-products of timber harvesting), excess agricultural wastes (when they aren’t used for composting), and rubble from tearing down or renovating buildings. moghtaderi et al. (biores. ( ), - ) discussed various underutilized classes of cellulosic biomass. reasons to consider motor fuel as a premium product as was noted in a review article (biores. ( ), - ), one can consider motor fuels to be highly engineered, premium products. they are designed to meet exacting specifications, delivering dependable power, lubrication, and clean running over a wide range of temperature and operating conditions. recent upward excursions in price are a continual reminder to us of how dependent upon motor fuels we have become. the word “burn,” as used in the title of this essay, can suggest a careless oxidation of biomass, as in the case of a campfire. in contrast to the inefficiency of a campfire, in technical terms, one might argue that motor fuels do their “job” of turning engines in an extremely effective and dependable way. on the other hand, it is easy to believe that much higher miles-per-gallon could be achieved either through legislation or higher prices. too valuable to burn, when there are other uses in light of these thoughts, the answer to the title question (are lignocellulosic resources too valuable to burn?) should be a qualified “yes.” yes, these resources are indeed “too valuable to burn” if they are combusted in an inefficient way, especially if such burning does not displace an equivalent amount of fossil fuel. the answer also is yes if there are customers and processes available for many alternative uses, such as those outlined by many authors of articles in this journal. also, the answer probably should be “yes” if the questioner has pinned hopes of solving the energy crisis by sole reliance on biofuels. there simply is not enough excess cellulosic biomass to meet the projected needs for fuel in the long term. the book energy for the st century by roy nersesian (sharpe, ) explains the sustainable limits of biomass production. maybe the best answer is to think of motor fuels as a possible “default” bi-product, the kind of bi-product that can fill out the portfolio of products from a well designed and optimized biorefinery. another way to answer the question is to examine some of the other most likely ways to meet the increasing demands for motor fuels and other forms of energy. some of the most promising approaches include direct solar, passive solar (especially for heating), wind, hydroelectric, and geothermal. perhaps even more important, in terms of solving short-term problems, will be improvements in efficiency, including increased use of public transportation, electric vehicles, and low-energy housing. maybe it is better that those houses be made with wood, representing high-end uses, rather than that either they or the vehicles parked in the driveways be fueled mainly with lignocellulosic byproducts. if too much of the lignocellulosic biomass is used as fuel, then not enough of the resource may remain for various higher-value applications. . .j.ijepe. . international journal of energy and power engineering ; ( ): - http://www.sciencepublishinggroup.com/j/ijepe doi: . /j.ijepe. . issn: - x (print); issn: - x (online) methodology article potentials for sustainable power supply in nigeria: an overview of energy resources in western nigeria israel dunmade earth and environmental sciences department, mount royal university, calgary, canada email address: idunmade@mtroyal.ca to cite this article: israel dunmade. potentials for sustainable power supply in nigeria: an overview of energy resources in western nigeria. international journal of energy and power engineering. vol. , no. , , pp. - . doi: . /j.ijepe. . received: march , ; accepted: april , ; published: june , abstract: availability of affordable energy is essential for the improvement of living standard and economic growth in any country. this study examined available energy resources in western nigeria and analyzed how they can be harnessed for sustainable energy supply. the study approach used involved literature survey, observation tour of some locations across the region and analysis of the observed scenario. the development of the proposed sustainable solution is based the study of countries in similar situation and how they were able to surmount their energy supply problems as well as personal understanding of the necessary adjustments for differences in locational factors and culture. the framework recommends integration of small number of abundantly available renewable energy sources at a scale manageable by locally available hands and in collaboration with all the stakeholders. it is believed that the proposed sustainable energy technology would ameliorate the persistent energy problems in the region. the proposed energy supply system is also expected to be economically affordable, environmentally friendly and culturally compatible. keywords: affordable energy, energy management, hybrid energy, western nigeria . introduction energy is required for virtually anything we do in our daily lives. energy is needed for preparing the food that we eat, for various types of self-propelled transport devices, for water treatment and distribution, for wastewater treatment, for manufacturing, for communication and various entertainment and leisure activities. most energy needs are required in the form of electricity. however, a number of developing countries like nigeria and businesses operating in their domain have been suffering from epileptic supply of electric energy over a very long period of time. the situation has badly impacted potable water supply, waste management, and health care delivery. it has also weakened industrialization in the country. furthermore, unstable electric power supply has significantly undermined various efforts aimed at achieving sustained economic growth, increased competitiveness of indigenous industries in domestic, regional and global markets as well as employment generation. this study is aimed at reviewing the current state of energy production and supply in nigeria, examining the root causes of the problems and propose sustainable solution to them [ - ]. . current state and approach to electric energy supply in nigeria according to kpmg [ ], there are currently grid-connected generating plants in operation in the nigerian electricity supply industry (nesi) with a total installed capacity of , . mw and available capacity of , mw. most generation is thermal based, with an installed capacity of , . mw ( % of the total) and an available capacity of , mw ( % of the total). hydropower from three major plants accounts for , . mw of total installed capacity (and an available capacity of , mw). there are also alternative electric energy supply by corporate organisations and private individuals. majority of them are from petrol or diesel powered generating sets. in addition, there are also some solar power and small hydro based electric power systems, especially in the rural areas. a israel dunmade: potentials for sustainable power supply in nigeria: an overview of energy resources in western nigeria number of individuals and government agencies are also making some effort in developing other alternative sources of electric energy. the federal government is also pursuing embedded power supply avenue whereby private and corporate generators sell power directly to specific distribution company. but most of these energy facilities are designed for large scale power supply. . causes of energy production and supply problems in nigeria majority of the current energy supply facilities in nigeria require steady supply of fossil fuel that does not only pollute our environment but are also not available at crucial times due to infrastructure breakdown from vandalism and inadequate maintenance. history of electric power development in nigeria showed that it started small, but it later evolved to regional power supply facilities. the regional energy facilities were later merged to become a monopoly. meanwhile the ever increasing population growth and expanding economy resulted in increased energy demand. however, the demand outgrew the supply to the point where the demand progression outpaced the increase in energy investment and supply. for instance, it has been estimated nigeria’s immediate electricity requirement stands at , mw for it to achieve a near regular power supply to domestic and industrial users in the country, but the country currently generates a meagre mw on average, out of which about mw is distributed to the approximately per cent of her population that has access to grid electricity [ , - ]. similarly, the increased responsibility of the energy monopoly seems to be beyond the capability of its managers in surmounting the daily emerging new problems. in addition, the energy organization was largely managed like government bureaucracy which further compounded its problem of being able to meet the needs of its clients. furthermore, government attitude, bad top management attitude, contractors’ attitude, poor maintenance planning, spare parts’ availability problem, lack of continuity in policy resulting from changes in government and lack of competitiveness exacerbated the problems. moreover, incessant equipment vandalization and theft, lack of manpower proactiveness, inadequate manpower training/education, equipment vandalization, drought, inadequate gas supply, wrong location, lack of policy continuity, limited automation, lack of energy mix technology, and competitiveness crippled the activities of the energy supply organization. efforts have been made by various levels of government and private organizations at solving the problems. dismemberment of the monopoly in recent past and a number of policy changes are among the efforts but unfortunately they are yet to yield any positive result [ , , ]. in view of the undertaken study, the author believed that sustainable solution to the problem would require a shift from the current approach to regional or district based energy generation and supply system that focuses on harnessing locally abundantly available renewable energy resources at a manageable scale and in an integrative manner. this belief informed the focus of this study on the western region of nigeria. . western nigeria’s renewable energy resources endowment nigeria as an entity is blessed with abundant varieties of energy resources both renewable and non-renewable. the abundance of each of these energy resources varies from one location to another. in view of the ongoing global trend, this study is focused on locally available energy resources in western region of nigeria. among the abundantly available energy resources in the region include solar, hydro, biomass, and wind (offshore). . . solar energy resource the location of nigeria just above the equator placed it in a vantage position for abundant sunshine all year round and thus endowed it with enormous solar energy potential. nigeria receives approximately hours of non-stop intensive sunshine throughout the year. according to iwayemi [ ], nigeria receives about . - . kw/m per day of solar radiation. although the solar intensity in the western nigeria is not the same as the northern part, an estimated mw of energy can be generated in western nigeria from solar sources. however, the region is yet to tap this abundantly available resource for its energy supply. . . water resources according to usaid [ ], nigeria has potential for , mw in large hydro power plants as well as up to mw in small hydro-power projects. western region is particularly blessed with many fast flowing rivers and large streams that run across the region. among such rivers and big streams with many municipalities near them are oshun, owena, oshin, erinle (otan), ogun (yelwa), oyi, ogunpa, oba, ogbesse, shasha, ominta, tesi, wuru, asa, ase, osiomo, mim, and atakpo (figures and ). many of these rivers and streams have sites along their courses where the head (fall) of water is two or more metres. thus, micro-, mini- and small hydro categories of electric energy (i.e. kw to mw power output) can be generated from those sites (table ). exploring such small scale renewable energy source that has little or no ecological footprint would go a long way in helping to solve the energy deficit in the region [ , - ]. . . biomass resources quoting simonyan and fasina [ ], “biomass consists of organic materials that are plant or animal based, including but not limited to dedicated energy crops, agricultural crops and trees, food and fiber crop residues, aquatic plants, forestry and wood residues, agricultural wastes, biobased segments of industrial and municipal wastes, processing by-products and international journal of energy and power engineering ; ( ): - other non-fossil organic materials.” western nigeria’s regional vegetation range from being swampy forest in the south to guinea savanna vegetation in the north. an estimate of about % of the region is in the mangrove forest zone, % is under forest vegetation while the rest % is under guinea savanna vegetation. iwayemi [ ] also reported that nigerian biomass endowment stands at million tonnes per year. about . million tonnes of woody biomass could be harnessed for energy energy supply from the region. in addition to woody biomass, there are other significant sources of bioenergy. there are many big municipalities like lagos, ibadan, benin city, akure, ilorin, oshogbo, abeokuta, oyo, benin, asaba, and sapele where large quantity of municipal solid wastes are produced daily. electric energy can also be generated from these solid wastes. energy can also be generated from human and livestocks poops in this region. utilizing the huge quantities of agricultural residues and other wastes for energy production would increase available energy supply and reduce air pollution from burning fossil fuel. it will also prevent surface and groundwater contamination from dumping. in addition, it will increase the energy mix and balance in nigeria’s western region. [source: http://scialert.net/fulltext/?doi=rjp. . . &org= ] figure . map of south western nigeria showing the study area and the three states the river traversed. [source: http://www.fao.org/docrep/ /ad b/ad b .htm] figure . major rivers in nigeria. israel dunmade: potentials for sustainable power supply in nigeria: an overview of energy resources in western nigeria table . categories of hydro energy. hydro category power range no. of homes powered pico kw – kw – micro kw – kw – mini kw – mw – , small mw – mw , – , medium mw – mw , – , large mw+ , + [source: renewables first ( )] . a sustainable approach to solving electricity supply problem in western nigeria from a lifecycle perspective although western region of nigeria have abundant sources of energy resources, they are yet to be adequately harnessed for public utilization. in view of the protracted and seemingly unsurmountable problems of large electric energy supply in nigeria, this research is proposing a new approach to solving the energy supply problem. the proposed approach is a municipal (or a group of small number of municipalities) scale integrated energy supply system that is based on collaborative lifecycle sustainability design and management (figure ). . . principles of collaborative lifecycle sustainability energy supply system design and management a reliable electric energy supply system that is suitable for western nigeria would need to be an integrated sustainable energy system developed and managed at local level in a collaborative manner and from a lifecycle perspective. integration of various energy sources is necessary because it has been recognized that no single energy source can provide all the energy required by any country or region. a mix of technologies and sources of energy, especially renewable sources, that are abundantly available and/or well suited for a municipality or a region would have to be employed. such a “sustainable energy paradigm would need to establish and maintain multiple linkages among energy production, energy consumption, human well-being, and environmental quality” [ - ]. establishment and maintenance of the multiple linkages would require involvement of all the stakeholders throughout the entire spectrum in a collaborative manner. this is necessary because genuine collaboration triggers a sense of responsibility for and ownership of what is created. although collaboration takes time and require commitment, however when stakeholders are involved from the beginning of a project on an equal status footing, it engenders rapport and reduces the tendency of a party to jeopardize its success. moreover, it is a win-win approach that enables the stakeholders to table their interests and how they could be accommodated. in addition, collaboration enables the team to identify potential sources of problems in the project and thereby provide opportunities to prevent them or make adequate preparation on how to minimize the risk. figure . steps for establishing a hybrid energy plant that is collaboratively designed for lifecycle sustainability. international journal of energy and power engineering ; ( ): - approaching energy supply from a lifecycle perspective facilitates identifying and quantifying various issues that could affect the system at each stage of its lifecycle from cradle to grave. so, the lifecycle sustainability concept evaluates the economic, ecological, social and institutional impacts of the system in addition to the technical aspects at each stage of the system’s lifecycle [ , ]. locality factor in terms of abundance of available resources and in the system management is crucial for a number of reasons. one of the problems of electric energy supply problems in nigeria is lack of adequate regular supply of gas needed to power the generating systems. capital cost installation and the cost of monitoring pipeline network for transferring gas from a far distance source to the power generating plant that is far away are huge and may be unaffordable. the long distance between the gas source and the plant using the gas makes the pipeline susceptible to vandalism and sabotage which is one of the current problems. locating an electric energy generating plant where the resources needed for operating such plant is abundantly available will eliminate those costs and improve the power availability. moreover, depending on acquiring resources needed for operating a plant from another jurisdiction increases power availability risk because political changes or relationship can lead to disruption of supply and many other restrictions that may arise in the future. furthermore, locally managing the system in a collaborative manner does not only create a sense of ownership and responsibility, it also foster easier physical monitoring of the facility and timely intervention whenever any situation that may negatively impact smooth operation of the system may be about to arise. in addition, involvement of the local people is beneficial because of their knowledge of the terrain and history of the location, inhabitants and culture which may affect the system at one point or the other. . . the proposed framework the process starts with the development of the project chatter and the appointment of a project champion who will facilitate the whole process. this is then followed up with identification of stakeholders, consulting them and requesting them to appoint a representative. a search conference is then organized for visioning exercise. this could be a one or two day meeting or series of meeting where every participant has the opportunity of providing insight to their perceptions on the proposed projects. it is at this meeting that ground rules for discussion and decision making are established. another expected outcome of the conference is a pathway to follow for the design, development and management of the proposed energy supply facility. an advisory committee and working groups may also be formed at this meeting or a procedure for their formation may be developed at the meeting. the search conference will be followed by a design charrette consisting of planners, engineers, architects, community leaders, public officials and citizens working together to envision and evaluate various alternatives in terms of established criteria for long term economic, social and ecological sustainability of the project. the group is expected to come up with a decision on the hybrid (i.e. mix) of technologies and sources of energy that would be developed as energy supply system for the municipality or the region. the design charrette is usually a two or three day workshop. an implementation committee with various working groups as sub-committees then takes over the results establish a management structure, performance standards, and timeline for implementation of various phases of the project. there are several merits in this proposed approach. these include that fact that it is modular, flexibly deployable, and promotes renewable energy technologies. it can also reduce poverty by providing highly rewarding employment opportunities for the local population. in addition, this approach would foster community harmony, minimise financial risk and lead to a smaller ecological footprint than the current centralised large scale energy supply system approach. . . effectiveness of the proposed solution in addressing the nigerian energy crisis there were reported cases of effective utilization of hybrid energy systems all over the world. many of them are deployed in developing countries like nigeria and significant number of them is being utilized in rural and remote locations [ ]. there are reported development and utilization of hybrid solar-wind systems in india and indonesia. moreover, several scholars have advocated bottom-up evolution of technology adoption and development. the prescriptions were based on the fact that adopting such approach in solving any important problem promote sense of belong, ownership and foster unity. it will also spur the community members to protect the infrastructure from vandalism and ensure effective 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( ). enabling environment and technology innovation ecosystem for affordable sustainable energy options. accessed online online on march at http://www.unescap.org/sites/default/files/indonesia% natio nal% sustainable% energy% strategy% report.pdf a novel, cost-effective design to harness ocean energy in the developing countries abstract—the world's population continues to grow at a quarter of a million people per day, increasing the consumption of energy. this has made the world to face the problem of energy crisis now days. in response to the energy crisis, the principles of renewable energy gained popularity. there are much advancement made in developing the wind and solar energy farms across the world. these energy farms are not enough to meet the energy requirement of world. this has attracted investors to procure new sources of energy to be substituted. among these sources, extraction of energy from the waves is considered as best option. the world oceans contain enough energy to meet the requirement of world. significant advancements in design and technology are being made to make waves as a continuous source of energy. one major hurdle in launching wave energy devices in a developing country like pakistan is the initial cost. a simple, reliable and cost effective wave energy converter (wec) is required to meet the nation’s energy need. this paper will present a novel design proposed by team sas for harnessing wave energy. this paper has three major sections. the first section will give a brief and concise view of ocean wave creation, propagation and the energy carried by them. the second section will explain the designing of sas- . a gear chain mechanism is used for transferring the energy from the buoy to a rotary generator. the third section will explain the manufacturing of scaled down model for sas- .many modifications are made in the trouble shooting stage. the design of sas- is simple and very less maintenance is required. sas- is producing electricity at clifton. the initial cost of sas- is very low. this has proved sas- as one of the cost effective and reliable source of harnessing wave energy for developing countries. keywords—clean energy, wave energy i. i. introduction espite technological advancement in the petroleum extraction, discovery rates of new oil reserves are falling every day. the world is using its remaining oil reserves at a prodigious rate. one reason for the increased demand of oil is the gradual increase in world population. the huge burning of fossil fuels has introduced the world with a new problem of global warming as well. the need for clean and continuous source of energy has emerged the need to explore new methods for harnessing energy around the world. there are many wind and solar energy farms built across the world but the problem is still persisting. oceans cover almost % of the earth surface and they contain a tremendous amount of energy. a rough estimate concludes that there is , - , twh/yr or - tw of wave energy in the entire ocean [ ]. this enormous amount of energy is enough to alleviate the problem of energy from the world. in the last two centuries, inventors have proposed many ideas for utilizing wave energy. the research in this field gained popularity after the oil crisis of . in the same decade stefan salter made the most efficient wave energy device. the idea of wave energy lost its strength in early s, when petroleum prices declined. the idea of harnessing wave energy has centralized the world again because now oil crisis came with a threat call of extreme global warming as well. although developed countries have induced a heavy amount for the development of new projects but the developing countries are still dealing with their economic crisis. now days, pakistan is also facing the problem of energy crisis. the energy crisis in pakistan results in heavy load shedding. pakistan has about km long coastline [ ]. the presence of strong waves along the makran coast predicts the future of wave energy utilization in pakistan [ ]. a rough estimate shows that the wave energy density in some region near the pakistan coastline is kw/m . although this energy density is very low comparable to other locations in world but still it can solve the problem of power shortage of a big city like karachi. this paper intends to provide a brief introduction about wave energy, its importance and in the end a new wave energy device named as sas- is also presented. sas- patent (patent# / ) has been filed in the intellectual property organization (ipo) of pakistan. it is basically a continuation of work carried out at pakistan navy engineering college, nust. sas- is also a successful device and it contains a linear generator. sas- was a successful device but the results obtained from it were not good because of an inefficient linear generator. sas- is made to operate in shallow water. it contains a rotary generator. the results obtained from sas- are very good and also the money invested on it is very low. sas- has proved itself as a successful cost-effective wave energy converter. sas- is in its early development stages. it is expected that further research on sas- will lead this device as one of the successful wave energy conversion device. ii. ii. ocean wave physics like other waves, ocean waves are caused by the disturbance in medium. this disturbance is due to the wind blowing over the surface of ocean which transfers energy. this energy transfer could be seen as a hump in the medium. in an ocean instead of water energy is travelling at the speed of wave. in deep sea a resting object moves in a perfect circle. the diameter of the circle is equal to the wave height [ ]. fig. illustrates the wave particle motion in deep water. the circular motion of the particles diminishes near the bottom of sea bed. s. ayub, s.n. danish, s.r. qureshi d a novel, cost-effective design to harness ocean energy in the developing countries world academy of science, engineering and technology international journal of economics and management engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e co no m ic s an d m an ag em en t e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/a-novel,-cost-effective-design-to-harness-ocean-energy-in-the-developing-countries/ http://waset.org/publication/a-novel,-cost-effective-design-to-harness-ocean-energy-in-the-developing-countries/ http://scholar.waset.org/ - / fig. wave particle motion in deep water [ ] wave length determines the size of the orbits of molecules with in a wave and the water depth determines the shape of orbits. in deep sea, wave particles move without the loss of any energy. in shallow water the water particles loses its energy due to the frictional effect with bottom. in this region wave particles move in elliptical form. just near shore the effect of bottom friction increases so much that the crest starts moving faster than its supporting base and a wave break. iii. iii. wave energy the calculation of wave energy is very important in designing a particular wave energy converter. this factor helps us in determining the size of wave energy converter. one important parameter involve in wave energy calculation is wave velocity. a. wave velocity there are two measures for wave velocity. the phase velocity and group velocity. phase velocity is the velocity of an individual wave [ ], [ ]. for deep water ( ) where ( ) so ( ) where g is the acceleration due to gravity, λ is the wavelength and t is the time period of wave. the group velocity is the velocity of the packet of waves. in deep water the group velocity is half of the phase velocity. ( ) in deep water the velocity of the waves remains constant. as the wave reached in shallow water the velocity of wave start decreasing. in shallow water, the frictional force acting on the wave decreases the wave velocity. b. energy density and power density the energy density of the wave is the mean energy crossing a vertical plane. [ ],[ ] ( ) the power density can be found by dividing the energy density by the time period. ( ) c. power per meter of wave front power per meter of wave front is determined by multiplying the group velocity with the energy density [ ],[ ]. ( ) in terms of phase velocity it can be written as: ( ) by using the relation of phase velocity ( ) reduces to ( ) in term of significant wave height ( ) d. power intensity (iz) power flow intensity shows the variation shows the variation in power for the different value of depth for a single wave [ ]. ( ) where ( ) z is the vertical downward distance from mean surface water level. i( ) is the intensity of wind at surface of sea. in deep sea % of energy is stored within a range of -λ/ <z < . hence a wec should be placed inside that range of depth. iv. iv. wave energy converters there are many ways to classify wave energy converters (wec). this classification is very important for the basic understanding of wec. wec’s can be classified according to their horizontal extension and orientation. a. point absorbers if the extension is very small as compared to typical wavelength then it is called as point absorber. fig. illustrates world academy of science, engineering and technology international journal of economics and management engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e co no m ic s an d m an ag em en t e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/a-novel,-cost-effective-design-to-harness-ocean-energy-in-the-developing-countries/ http://waset.org/publication/a-novel,-cost-effective-design-to-harness-ocean-energy-in-the-developing-countries/ http://scholar.waset.org/ - / the working principle of point absorber. the buoy moves up and down as the wave passes. this motion could be used to generate electricity by the use of linear generator. as they absorb energy at a point from wave so they are named as point absorbers. fig. concept of point absorber devices [ ] a typical example of point absorber type devices is archimedes wave swing (aws) as shown in fig. the aws is fully submerged. it consists of two cylinders. the lower cylinder (silo) is fixed to the seabed while the upper cylinder (floater) moves up and down under the influence of waves .the interior of aws is filled with air. this tends to move the floater into its original position when a wave passes. the relative motion between the two cylinders is used to drive a linear generator. fig. aws concept [ ] b. line absorbers if the horizontal extension is comparable or larger than the wavelength it is called as line absorber [ ]. they are further classified into attenuators and terminator type devices. if a line absorber wec is placed parallel to the direction of the propagation of wave then it is called as attenuator. the world most successful commercially launched wec pelamis is an example of attenuator type device as shown in fig. the pelamis is a semi-submerged, articulated structure composed of sections linked by hinged joints. the motion of these joints is resisted by hydraulic rams, which pump high-pressure oil through hydraulic motors. the motors drive generators to produce electricity. fig. pelamis wec if a line absorber type wec is placed normal to the direction of propagation of wave then it is called as terminator type device. an early example of terminator type device is proposed by salter duck as shown in fig. and it is considered to be the most efficient device. v. sas- depending upon the need and importance of energy in our daily life, a new wec named as sas- is made. the aim of sas is to generate electricity. further aim of sas- is to set a foundation for the wec’s in pakistan which will further lead us to make a successful wec for pakistan. a. important features of sas- following are the important features of sas i. it converts both the kinetic and potential energy of waves. ii. it can convert energy in deep water and shallow water iii. highly robust structure iv. simple v. sas is best across the manora, gaddani, clifton, hawks bay b. concept of sas- sas is what is sometimes referred to as a ‘terminator’. the device is aligned parallel to the wave fronts, at right angles to the principal wave direction, thus ‘terminating’ the waves as shown in fig. fig. concept of salter duck wec [ ] world academy of science, engineering and technology international journal of economics and management engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e co no m ic s an d m an ag em en t e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/a-novel,-cost-effective-design-to-harness-ocean-energy-in-the-developing-countries/ http://waset.org/publication/a-novel,-cost-effective-design-to-harness-ocean-energy-in-the-developing-countries/ http://scholar.waset.org/ - / the device comprises of a float which is slightly submerged in sea water. this float is aligned to the principle wave direction so that it engages with the maximum number of waves. this float will heave with the water particles around it as the wave passes under it. energy is extracted by in effect damping this motion. this mechanical energy is transferred by a chain drive to the fly wheel. the fly wheel stores the wave energy. a shaft is connected with the fly wheel which is further connected with a rotary generator to produce electricity. c. design of sas- the process of energy conversion from the waves till the generation of electricity in sas- is comprises of three steps . front end conversion the front end conversion converts the wave into mechanical energy. it is the most important part in designing a wec. an enormous amount of energy is present in waves and if the front end conversion is perfect then it can cover easily the deficiencies in the later conversion mechanism. for front end conversion a float is designed that interacts with the incoming waves. the rear side of the float is connected with an arm which is further pinned at a shaft. this mechanism tends to oscillate the float as the wave interacts. the weight of the float is decided in way that, within suitable area of application the buoy should be submerged up to λ/ of depth so that maximum energy is transferred to the float [ ]. λ is the mean wavelength of the waves passing through this region. figs. and show the shape of the floats decided at initial stage for comparison. if we consider parallel stream line flow of water coming towards float- then they will try to cancel each other effect after collision. in case of float- they will become parallel after collision. hence float- is used for the wec. it is designed as a terminator type device for getting maximum efficiency. so its length is comparable to wavelength. the final form of the front end conversion mechanism is shown in fig. fig. float- for sas- fig. float- for sas- . intermediate conversion the power transmitted by the wave to the float is further converted into rotary motion by a set of chain drives. if mechanical losses are neglected then the power transmission in the sprockets is governed by eq. . there are three chain drives used in sas- to obtain the required rpm and torque for the generator. ( ) here τ , τ is the torque and ω , ω is the angular velocity of drive and driven sprocket gears respectively. a flywheel is used to store energy. this stored energy is used to drive the generator continuously at constant rpm. eq. shows the energy stored in a flywheel .a kg flywheel is used in sas- .flywheel designing parameters are adjusted after monitoring the time between two wave crest. ( ) if is the polar moment of inertia of flywheel and ωf is the angular velocity of flywheel. . electromechanical conversion for the electromechanical conversion in sas- , a dc geared generator is used. it has an in built gearbox so that less rpm is required for the generator. the generator shaft is driven by a chain drive. this chain drive connects the generator shaft with the flywheel so that the generator runs with a smooth and continuous rpm. d. structure of sas- a simple robust structure is used to hold sas- . the base of the structure is fixed in sea bed. the fixed structure provides a rigid support for the float to stand against waves. hence maximum energy is transferred to the float as there is no relative motion in between the structure and float. e. complete assembly of sas- the complete assembly of sas- is shown in fig. the direction of propagation of waves is normal to the float motion. all the assembly is mounted on a fixed standing structure. this complete assembly is placed in sea at a depth where the float and the mean surface level of water (swl) become parallel. vi. v. results of sas- the testing of sas is done at various stages. at first float was fabricated and tested individually to check it response fig. float of sas- connected with arm world academy of science, engineering and technology international journal of economics and management engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e co no m ic s an d m an ag em en t e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/a-novel,-cost-effective-design-to-harness-ocean-energy-in-the-developing-countries/ http://waset.org/publication/a-novel,-cost-effective-design-to-harness-ocean-energy-in-the-developing-countries/ http://scholar.waset.org/ - / against the incoming waves. then the complete assembly was tested. the results obtained at every stage are further used in making some modifications. these results are compared with the help of energy stored in flywheel. table relates the results obtained at different stages of test. table i results of sas- st test nd test rd test average rpm of flywheel energy stored in the flywheel j . . j vii. vi. conclusion this paper gave an overview of the work done by team sas in designing a successful wec. its success on such a small scale has proved it as a successful wec. the design of sas- is in its early stages. it is expected that small modifications and further research will lead sas- on commercial level. viii. nomenclature wec wave energy converter owc oscillating water column aws archimedes wave swing sas sas is the name of our group swl mean seawater level (surface) e density wave energy density e wave front energy per meter wave front p density wave power density p wave front power per meter wave front h sea depth Ω wave frequency λ or l wavelength ρ water sea water density g gravitational constant a wave amplitude h wave height t wave period v phase velocity cg group velocity hm significant wave height fig. complete assembly of sas- world academy of science, engineering and technology international journal of economics and management engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e co no m ic s an d m an ag em en t e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/a-novel,-cost-effective-design-to-harness-ocean-energy-in-the-developing-countries/ http://waset.org/publication/a-novel,-cost-effective-design-to-harness-ocean-energy-in-the-developing-countries/ http://scholar.waset.org/ - / references [ ] richard boud, “status and research and development priorities, wave and marine accessed energy,” uk dept. of trade and industry (dti), dti report # fes-r- , aeat report # aeat/env/ , united kingdom, . [ ] n. a. zaigham, z. a. nayyar, “prospects of renewable energy sources in pakistan”, proceedings of comsats conference on renewable energy technologies & sustainable development, . [ ] t. garrison, “oceanography, an invitation to marine sciences”, brooks/col cengage learning, . [ ] j. falnes “a review of wave-energy extraction”, p.p. – , marine structures, vol. , pp - , elsevier, . [ ] m. e. mccormick, “ocean wave energy conversion”, dover, [ ] a. muetze, j. g. vining, “ocean wave energy conversion–a survey”, electrical and computer engineering department, ieee, . [ ] t. k.a. brekken, a. v. jouanne, h. y. han, “ocean wave energy overview and research at oregon state university”, unpublished. [ ] http://earthsci.org/mineral/energy/wavpwr/wavepwr.html [ ] s. ayub, s.n danish, s.r. qureshi, s.r. rehman , a. ahmed, “a novel approach to harness ocean energy”, proceedings of the th international conference on applied sciences and technology, islamabad, pakistan, - january, . [ ] http://news.bbc.co.uk/ /hi/uk_news/scotland/highlands_and_islands/ .stm [ ] http://commons.wikimedia.org/wiki/file:point_absorber.jpg [ ] http://scubageek.com/articles/wwwparticle.html [ ] s.ayub, s.n danish “patent # / , a wave energy converter”, intellectual property organization, pakistan. world academy of science, engineering and technology international journal of economics and management engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e co no m ic s an d m an ag em en t e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/a-novel,-cost-effective-design-to-harness-ocean-energy-in-the-developing-countries/ http://waset.org/publication/a-novel,-cost-effective-design-to-harness-ocean-energy-in-the-developing-countries/ http://scholar.waset.org/ - / ductions in power use might be effected or which could be implemented should a scarcity of power develop. barry commoner will consider the ecological importance and social implications of reducing reliance on power-intensive production technologies. john todd will discuss biotechnic decentralization as an alternative to the energy crisis; herman daly will consider the eco- nomic implications of a scarcity of en- ergy; and richard stein will review the implications of energy use and need from the standpoint of the architect. dean e. abrahamson university of minnesota medical school, minneapolis december geological implications of solid waste landfill * d; d~~~~~~~~ f x dfff'ff ffe d xf l i- x - -- (left). well-managed sanitary landfill opel ready for new development. trees were reta domestic and industrial solid wastes are being produced at an ever-increas- ing rate. every method for disposal of this by-product of our highly produc- tive society is encountering objections with the gradual awakening of an en- vironmental conscience in the public mind. with a concern for air pollution, incineration in major metropolitan areas is under attack; even incineration at its best leaves a residue which re- quires disposal. open dumping and burning, common methods for handling solid waste disposal, are under attack for health and esthetic reasons. in response to the recognized short- comings of other methods of solid waste disposal, the utilization of solid wastes for sanitary landfill has been the fastest growing technique in the (right). restored landfill area last decade. a landfill is a man-made geologic deposit with rather unique physical and chemical properties. its composition is strikingly inhomogene- ous, as is its particle size. the rate of compaction-settling is extremely high in comparison with natural geological sediments. the porosity and permeabil- ity of solid waste landfills vary within wide limits and the leachate which seeps forth is frequently a biological and chemical contaminant. the scheduled symposium on "geo- logical implications of solid waste landfill" is dedicated to the principle that "out of sight, out of mind" is no longer an acceptable basis for getting rid of solid wastes in the ground. geologists, hydrologists, planners, and landscape architects will address them- selves to the definition and recognition of the extent to which various geologic and hydrologic conditions in the ground favor or limit the selection of solid landfill waste disposal sites. there has also been developing a new expertise in the physical and chemical effects of the landfill waste materials upon thc sites themselves. the symposium will highlight many of the findings and parameters developed by leading re- searchers in this contemporary field. speakers and topics d. a. stephenson, what to do before the garbage truck a rrives. s. jackson hubbard, designt of a sanii- tary landfill. norbert b. schomaker, collstruction techniques for sanitary landfills. george m. hughes, hydrogeologic conz- trols on the movement of leaclhates from refuse. richard r. parizek and donald lang- muir, mantagement of leachates from sanzitary lazdfill. grover h. emrich, managemenzt of hazardous geologic conzditionis foor safe solid waste disposal. gary l. merritt and william c. buccia- relli, the geologic aspects in the plani- ning and implementtation of the penin- sylvania solid waste management act . edwin g. otton, solid waste disposal in the geohydrologic enviroiinment of marylanid. w. l. fisher and l. f. brown, jr., ge- ologic evaluation of santitary landfill sites, texas coastal zonie. arthur a. socolow state geologist and director, pennsylvania topographic and geological survey, harrisburg - december living systems: synthesis, assembly, origins several approaches to the artificial production of living systems will be re- viewed in this symposium. attention will be focused on systems and on the supporting levels of cellular construc- tion, especially the relevant macro- molecules. principal topics to be covered first are the chemical synthesis of contem- porary proteins (k. hofmann, uni- versity of pittsburgh) and nucleic acids (m. caruthers, m.i.t.). the assembly of such macromolecules into systems is emphasized through reports on ex- periments with polymers from living systems. many biomacromolecular preparations have been reassembled into organelles (d. j. kushner, univer- sity of ottawa); nuclei and cytoplasms of amoebas have been transferred from one membrane to another (j. f. danielli, state university of new york at buffalo); and models of primitive macromolecules (r. lohrmann and r. sanchez, salk institute; and d. l. rohlfing, university of south carolina) and of primordial cells and organelles (s. w. fox, university of miami) science, vol. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ december geological implications of solid waste landfill arthur a. socolow doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / . .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the trademark of aaas. is a registeredscienceadvancement of science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for thescience © by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / . .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ energy from a fishpond notes, news & comments study programmes on organization of assistance in the event of major disasters. the task of establishing and standardizing the termino- logy relating to major disasters has been entrusted to the spanish delegation, which will present this proposal at the next meeting, to be held on and december in istanbul, at the invitation of the turkish government. the fifth informal meeting of the ministers might be held in greece, at the invitation of the greek government, which will be setting up a european pilot centre for forecasting earthquakes. the parliamentary assembly of the council of europe is following with especial interest the work done in the fields of forecasting and prevention of disasters, and also on cooperation between the states of southern europe—not only to forecast disasters, but also to protect and safeguard the cultural heritage. directorate of press and information council of europe b.p. r f- strasbourg cedex france. the centre for science and environment in india the centre for science & environment (cse) was set up in in new delhi as a non-profit, non-governmental, quasi-academic, research organization. its aim is to pro- mote public awareness of the role of science and technology in indian national development. more specifically, it ex- plores issues concerning environment and development in india. it was founded by anil agarwal, an indian institute of technology graduate who had worked as a journalist on 'the hindustan times' and the 'indian express' in delhi and as the assistant editor of the earthscan feature agency in london. most of the research and writing staff of the cse are science graduates or journalists. one of the first activities for the cse was to run a feature service for newspapers. in , it published the state of india's environment—a citizens' report, which for the first time examined not only different facets of the deter- ioration of the country's environment in painstaking detail but also established the interconnection between those dif- ferent facets. the report, published as a hardback volume of nearly pages, won acclaim in india and abroad, and has become the biggest single source of information on the country's environment. * being reviewed for our journal by dr m.s. swaminathan, frs, fna, director-general of the international rice research institute and president of iucn.-ed. note : we would like to commend this initiative most warmly and express the ardent hope that it will be emulated in more and more countries having similarly enlightened heads of government who are disposed to seek independent expert advice on pressing or foreseeable environmental problems.—ed. three years later, the cse followed up with a second report*, which covered new ground and dealt with new problems, and which included a long section on the causes and consequences of the bhopal gas-leak tragedy. it has already sold some , copies and is exactly twice as voluminous as the first book. like the first report, it has been widely extracted and reviewed in the indian and for- eign press. prime minister rajiv gandhi has recently asked the cse, on the basis of the second report, to brief the entire indian cabinet of ministers and all the members of parliament on the threat to india's environment. yet another publication of cse is temples or tombs? by the undersigned, which deals with three industrial projects that triggered off environmental controversies in the country. one of the remarkable features of cse's activities is that it has until recently been able to support itself almost entirely by the sales of its books. it is now working on others, two of which are to be entitled 'india's cooking energy crisis' and the 'state of india's urban environ- ment'. the cse also does networking on environmental issues with ngos in india and abroad. darryl d'monte, cse fellow centre for science and environment vishal bhawan nehru place new delhi india. energy from a fishpond falling oil prices make little difference to poor farmers in the third world whose resources cannot be stretched to buy power at any price and who, all too frequently, are remote from principal sources of supply. hence the interest of a unesco enterprise in paraguay, to develop a device for on-farm supplies of energy from biogas. the biogas is produced by the breakdown of aquatic plants from a fishpond. microorganisms work on the aquatic plants (which can be supplemented with animal manure) to decompose them in a biodigester {see caption to fig. ) in which organic matter is further decomposed. it is based on a chinese model, and yields around nine cubic metres of gas a day. integrating the installation with a fishpond has several advantages: it helps the farmer to raise his energy capacity with the biogas, and it also increases his foodstocks with fish from the pond, as well as supplying fertilizers and animal fodder from the aquatic plants. unesco's regional office for science and technology (rostlac) in montevideo helped to develop the system, which was designed by research workers at the institute of basic sciences in the national university at asuncion, led by dr r. fitzpatrick, a former unesco official. the installation has been set up at the enrique de osso college for the promotion of rural women in asuncion. the students, who come from inland regions of the coun- try, will spread the idea in their own villages. a training course for peasants together with instruction manuals are foreseen. https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core environmental conservation hu. . energy from a fishpond—see text and fig. . photo • unesco features. the university research team plans to build up a com- plex large enough to cover the needs of a small rural farm. aquatic plants common to the area thrive under cultiva- tion, and several local species of fishes are easily bred. apart from the fact that it uses local materials and spe- cies in an ecologically closed cycle, the system has another considerable advantage: its low cost. an integrated system for an average rural family should cost under $ , so that the farmer should get back his outlay in under three years from gas production alone. martin viaene office of public information unesco place de fontenoy paris france. fig. . biodigester (below), and reservoir at the 'enrique de osso' college for the promotion of rural women, in paraguay. such a biodigester is commonly called a 'digester' and is a recipient in which organic matter is decomposed by microorganisms with pro- duction of gas that is burned to yield energy. photo: unesco features. https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core ~ ~ journal of pharmacognosy and phytochemistry ; sp : - e-issn: - p-issn: - jpp ; sp : - manjri asstt. prof. school of agriculture, itm university, gwalior, m.p., india ak singh asstt. prof. department of crop physiology, ndua&t, kumarganj, faizabad, u.p., india akanksha singh asstt. prof. school of agriculture, itm university, gwalior, m.p., india sarita devi gupta phd scholar department of biochemistry, ndua&t, kumarganj, faizabad, u.p., india girish pandey professor & dean, school of agriculture, itm university, gwalior, m.p., india correspondence manjri asstt. prof. school of agriculture, itm university, gwalior, m.p., india national conference on conservation agriculture (itm university, gwalior on - february, ) submergence tolerance in rice genotypes with reference to peroxidase activity manjri, ak singh, akanksha singh, sarita devi gupta and girish pandey abstract this study was conducted to evaluate the submergence tolerance, response of peroxidase activity among rice genotypes. rice genotypes viz., bad dhana, khawjii, sambha, lalkadhan, ndr , ir- , katy, ndr - , khaiyan, ndr , ir - - - , ndr , ndr , and swarna sub- were evaluated for their peroxidase activity on fifteen days of submergence. peroxidase activity was also recorded in normal as well as in submergence stress condition and maximum peroxidase activity under normal condition was noted in bad dhana and the minimum was noted in sambha at all the stages of observation whereas, under stress condition maximum peroxidase activity was shown by bad dhana at rd day and minimum peroxidase activity was noted in sambha at st day at all the stages of observation. in short peroxidase activities increased upto rd day their after declined trend were obtained. the results indicated that the submergence tolerance genotypes have higher peroxidase activity. keywords: peroxidase, submergence, tolerance, rice, genotypes introduction waterlogging is a serious problem that affects crop gas exchange in low-lying rain-fed areas. approximately % of the world’s rice (oryza sativa) farmlands are at a low elevation and irrigated by rain (bailey-serres et al. ) [ ]. under limited oxygen availability, photosynthesis and respiration are restricted, leading to an energy crisis, toxic products from anaerobic respiration and the accumulation of reactive oxygen species (ros) in plant cells (licausi and perata ; pucciariello et al. a; yang and hong ) [ , ]. several studies have focused on the important role of ros during hypoxia signaling under full submergence conditions (baxter et al. ; fukao et al. ; liu et al. ; yang and hong ) [ , , , ]. plants have evolved defense mechanisms naturally to scavenge aos by enzymatic and non-enzymatic antioxidant mechanisms. several antioxidant enzymes have been evolved in detoxifying aos. among them, superoxide dismustase (sod) is a major scavenger of o , which dismutises o into h o (bowler et al. ) [ ]. h o is scavenged by ascorbate peroxidase (apx), glutathione reductase (gr), catalase (cat), and some peroxidases (pox) (asada ) [ ]. ‘escape’ or ‘quiescence’ are two major types of adaptive response to submergence, seen in a wide range of species and based on the vigor of upward shoot elongation initiated by submergence (ram et al. ) [ ]. in most rice lines, the escape strategy takes the form of accelerated underwater elongation and is most marked in deep water lowland rice where vigorous stem extension prevents total submergence as floodwater gradually rises. however, leaves, stems and coleoptiles of almost all rice types elongate faster in response to submergence provided some oxygen is present. when fast shoot extension is insufficient to allow the plant to re-surface, the expenditure in energy and respirable substrates needed to support the faster underwater growth may threaten survival. the rice line ‘fr a’ is an exception to this general rule. in contrast to most other rice lines ‘fr a’ does not elongate faster underwater and thus conserves accumulated respirable biomass thereby adopting the so- called quiescence strategy (singh et al. ) [ ]. continuous anaerobic metabolism can result in the accumulation of phytotoxic end-products. when floodwaters subside, submerged plants encounter the rapid entry of oxygen, causing oxidative damage through overproduction of reactive oxygen species (ros) and toxic oxidative products (crawford, and fukao et al. ) [ , , ]. ~ ~ journal of pharmacognosy and phytochemistry materials and methods the experiment was conducted in earthen pots and submerged into cemented pond at the experimental site of the department of crop physiology n.d.u.a.&t., kumarganj, faizabad (u.p.). bold and healthy seeds of rice genotypes (bad dhana, khawjii, sambha, lalkadhan, ndr , ir- , katy, ndr - , khaiyan, ndr , ir - - - , ndr , ndr , and swarna sub- ) were sown in the pot. submergence was given to days old seedlings at vegetative stage in pot culture for days. at the time of submergence, water level was maintained at cm. the leaves were submerged in pond water. the level of pond water was maintained through water pipe. control was kept without any submergence. peroxidase activity was recorded at control and ( st day to th day) after days of de-submergence. peroxidase activity the activity of peroxidase was determined by the method at curne and galston ( ) [ ]. reagents: (i) phosphate buffer . m (ph . ), (ii) pyrogallol ( . n) (iii) h o ( . %) procedure: mg fresh leaf material was homogenized in ml of . m phosphate buffer (ph . ) and centrifuged at , rpm for minutes at low temperature. ml enzyme extract was taken in a test tube to which ml phosphate buffer (ph . ), . ml pyrogallol and . ml h o was added. the intensity of colour was measured at nm on spectronic . express result as enzyme unit g - fresh weight. result and discussion peroxidase activity was also recorded in normal as well as in submergence stress condition and presented in graph and maximum peroxidase activity under normal condition was noted in bad dhana ( . ) followed by khawjii ( . ) and the minimum was noted in sambha ( . ) at all the stages of observation whereas, under stress condition maximum peroxidase activity was shown by bad dhana ( . ). followed by khawjii ( . ) at rd day and minimum peroxidase activity was noted in sambha ( . ) st day at all the stages of observation. ushimaru et al. ( ) [ ] reported that the increased activity of these enzymes under submergence might be due to possible absorption of molecular oxygen from the surrounding water. the combined action of enzymes is important for detoxifying toxicity. sod merely acts on the superoxide anion, converting it to another reactive intermediate (h o ), and cat acts on h o , converting it to water and oxygen (mates ) [ ]. flood- tolerant genotypes under submergence can thrive by effective energy maintenance through lower leaf expansion, minimum elongation, less chlorosis (setter and laureles ), high dmp, high carbohydrate reserve, and a strong antioxidant enzyme system (sarkar et al. ) [ ]. similarly, a. anandana and p. arunachalamb ( ) [ ] reported that the activities of all antioxidant enzymes were significantly greater in tolerant/avoidance genotypes than in the susceptible (c ) genotypes under both submergence and desubmergence. seedlings of tolerant genotypes had higher survival, and the roots were more viable with greater capacity to elongate. moreover, they had higher peroxidase activity and lesser increases in both electrolyte leakage and malondialdehyde production during submergence. there were strong positive correlations between survival and some parameters measured during submergence such as root elongation (r = . **) and peroxidase activity (r = . **, at day of submergence) (ella et al. ). conclusion findings of this study indicate that the peroxidase activity was higher in submergence tolerant genotypes and lower in susceptible genotypes in all days ( st to th day) but at rd day after desubmergence highest activity was found in all tolerant genotypes. submergence treatment has enhanced the level of peroxidase activity. this indicated that the peroxidase activity could be utilized as the selection criteria for evaluating submergence tolerance in rice. acknowledgements the authors acknowledge the support rendered by narendra deva university of agriculture ant technology for providing the necessary facilities and dst-inspire fellowship for financial support. reference . anandana, arunachalamb p. relative proportion of antioxidative enzyme activity in locally grown indian rice cultivars (oryza sativa l.) under submergence condition. journal of plant interactions. ; ( ): - . . asada k. the role of ascorbate peroxidase and monodehydroascorbate reductase in h o scavenging in plants. in: scandalios jg, editor. oxidative stress and the molecular biology of antioxidant defenses. new york: cold spring harbor laboratory press, , . . bailey-serres j, voesenek la. life in the balance: a signaling network controlling survival of flooding. curr ~ ~ journal of pharmacognosy and phytochemistry opin plant biol. ; ( ): - . . baxter a, mittler r, suzuki n. ros as key players in plant stress signalling. j exp bot. ; ( ): - . . bowler c, montagu mv, inze` d. superoxide dismutase and stress tolerance. annu rev plant physiol plant mol biol. ; : . . crawford rmm. oxygen availability as an ecological limit to plant distribution. adv. ecol. res. ; : - . . curne mc, galston aw. inverse of gibberellins on peroxidase activity during growth in dwarf strain of pea and corn. plant physiol. ; : - . . fukao t, yeung e, bailey-serres j. the submergence tolerance regulator sub a mediates crosstalk between submergence and drought tolerance in rice. plant cell. ; ( ): - . . fukao t, yeung e, bailey-serres j. the submergence tolerance regulator sub a mediates crosstalk between submergence and drought tolerance in rice. plant. cell ; : - . . licausi f, perata p. low oxygen signaling and tolerance in plants. adv bot res. ; : - . . licausi f, weits da, pant bd, scheible wr, geigenberger p, van dongen jt. hypoxia responsive gene expression is mediated by various subsets of transcription factors and mirnas that are determined by the actual oxygen availability. new phytologist, b. . liu b, rennenberg h, kreuzwieser j. hypoxia induces stem and leaf nitric oxide (no) emission from poplar seedlings. planta. ; ( ): - . . mates jm. effects of antioxidant enzymes in the molecular control of reactive oxygen species. toxicology, ; : . . pucciariello chiara, pierdomenico perata. new insights into reactive oxygen species and nitric oxide signalling under low oxygen in plants. plant, cell and environment, . https://doi.org/ . /pce. . . ram pc, singh bb, singh ak, ram p, singh pn, singh hp et al. submergence tolerance in rainfed lowland rice: physiological basis and prospects for cultivar improvement through marker-aided breeding. field crop res. ; : - . . ruban av. evolution under the sun: optimizing light harvesting in photosynthesis. j exp. bot. ; : - . . sarkar rk, das s, ravi i. changes in certain antioxidative enzymes and growth parameters as a result of complete submergence and subsequent reaeration of rice cultivars differing in submergence tolerance. j agron crop sci. ; : . . singh s, mackill dj, ismail am. physiological basis of tolerance to complete submergence in rice involves genetic factors in addition to the sub gene. aob plants : plu , . . ushimaru t, shibasaka m, tsuji h. changes in levels of heme a, protoheme and protochlorophyllide in submerged rice seedlings after exposure to air. plant cell physiol. ; : - . . yang cy, hong cp. the nadph oxidase rboh d is involved in primary hypoxia signalling and modulates expression of hypoxia-inducible genes under hypoxic stress. environ exp bot. ; : - . international journal of recent technology and engineering (ijrte) international journal of recent technology and engineering (ijrte) issn: - , volume- issue- , january published by: blue eyes intelligence engineering & sciences publication retrieval number: e / ©beiesp doi: . /ijrte.e .  abstract: many people are using non renewable energy sources in high amount of their needs. some minerals are exhausting with the high usage, so it is obvious to depend on the renewable sources like solar & wind etc. in this paper a solar energy based water pump system with different time slots are proposed. the solar energy is converted into electrical energy by photovoltaic cells and it charges the battery. during day time battery stores the energy. in this project at s microcontroller are used. for this microcontroller the program is written for giving different time slots. one * lcd display is using to see the status of system. for adjusting contract display one variable resistor called ‘preset’ is used. one sensor is used to observe the water level and to send data back to the microcontroller. the manual on/off control of the system can be avoided with this sensor. this is a new method to operate motor / machine for a small duration. buzzer gives a beep sound. a transistor is used to drive the relay during on time period; relay is used to control the pump. a switching diode is used to control the reverse emf. the proposed system has the advantage of automatic switch off for the given time. this will be the one of best solutions for smart solar irrigation for farmers. in addition, this solar system controls the flow of water across the field. keywords: solar panel, at s microcontroller, water pump, * lcd display, battery charger i. introduction in every country irrigation plays main role in this paper we develop the automatic solar water pumping system at low cost for irrigation developing country. we arrange the one programmed senor module detect the temperature and soil moisture level and send this data to microcontroller. water level sensors also observe the water level and send the data to the microcontroller unit [ - ]. based on the sensor alerts microcontroller unit decide whether motor is on or off. this paper also describes the detailed working function of the microcontroller in soil. if the server is connected to the microcontroller system then the motor on and off can be controlled by using mobile phone. now a day’s most of the people are using solar energy [ - ]. the purposed system has the additional features to know the temperature and water flow of the system. in this paper a micro controller based mater pumping system using stand alone solar system is proposed. solar energy is used in this method for feeding the irrigation loads. revised manuscript received on january , . * correspondence author m. pratyusha*, asst. prof, eee dept, gitam school of technology, bangalore, india. email: pratyugitas @gmail.com b. nagi reddy, asst. prof, eee dept, vignana bharathi institute of technology, hyderabad, india. email: nagireddy @gmail.com c. v. vijay kumar, asst. prof, eee dept, vignana bharathi institute of technology, hyderabad, india. to make this system economical and effective, a battery system is adopted for this application. so the main aim of this paper is to cut down the cost and make the efficient water pumping system for a field irrigation system [ , ]. in private houses water is a playing major role. for pure water we are using purifiers. by using renewable energy we can reduce this electric water purification so automatically usage of electricity is also reduced [ ]. this solar energy converted into electrical to run the ac submersible pump. photovoltaic (pv) technique is created by solar energy. for irrigation purpose we are using microcontroller based water pumping system. basically agriculturist who have cultivated in india they are so far away from water source [ ]. these farmer needs to install water pumping system to irrigate their farm area. there is required electrical power by supplying from governments it's so expensive for maintaining. now a day’s solar water pump system is one of system is applied photovoltaic panel. in day it's observe the heat from sun and it's convert to power and it's operate [ ]. in this process reduce the cost compare to diesel and electrical energy cost. free from the pollution. in this process we store the energy in battery and run at night time. therefore this paper aim is design the development of solar water pump with charge controller for battery. now a day’s water heating purpose we use different machines. in this paper the overview water heater use the solar energy for domestic water heating purpose. its expensive compare remaining machines that's the reason we develop solar energy system include green energy source. thermal collector presents in the equipment its collect the heat. for control purpose we the sensors and plc's actuators finally we control heat and use for domestic purpose [ ]. for solar applications we can use dc motors also. this dc motor is controller for solar water pump. by using three phase induction motor we will get good efficiency. photovoltaic cells usually generated different types of variable power. if dc voltage obtained from pv system it's increased by the help of buck boost converters this energy is used in different applications. in this paper we develop the dc- dc converter double the buck-boost operation [ , , ]. this converter used in low power application like solar water purifier system. in this process we used the conversational converter instead of two controlled switch only one switch is arranged it's made up of mosfet. for good quality and efficiency purpose two inductors and two capacitors are used as energy transferring elements in the circuit design like dbb converter is analyzed with closed loop control using pi controller. this dbb converter we give the power supply to the unit of and electrical water purifier and water get purified. implementation of microcontroller to control solar water pump at different time slots m. pratyusha, nagi reddy. b, c. v. vijay kumar implementation of microcontroller to control solar water pump at different time slots published by: blue eyes intelligence engineering & sciences publication retrieval number: e / ©beiesp doi: . /ijrte.e . global system is very high demand for electrical energy and water. for electrical energy we have renewable energy sources like solar, wind, tidal etc. an automated solar power agriculture pumping system will give good results for electricity and water. ii. methodology a. at s microcontroller fig . at s microcontroller now days in embedded system we are using these microprocessors and microcontrollers. these are programmable device. microcontroller contains a single metal oxide semiconductor (mos) integrated circuit chip, and also contains one or more cpus along with memory and input /output terminals. these are used in automatic controlled devices like remote controls, toys, automobile engine control systems. the at s obtained from atmel microcontrollers. it is low power and high performance -bit cmos microcontroller with k as flash memory and bytes of ram. this controller having different ports, each one of them having i/o ports, so total i/o ports. most of the ports used for two different functions. one is for input /output operation and other is one for counting external pulses, serial data transfer. some microcontrollers use bit word and operate at khz. b. bridge rectifier fig . bridge rectifier rectifier converts ac signal in to dc signal, which flows in one direction. this process is known as rectification .in this rectifier we can use either full wave, half wave, single phase ac, three phase ac. these are used in different devices like dc power supplies, radio signals, home appliances for providing dc voltage. the main advantage of this bridge rectifier is polarity of the output is same as polarity at the input. another advantage of this rectifier is if we use centre tapped transformer we can get output voltage is double. here capacitor will store the energy. in this rectifier we are using step down transformer to change the amplitude of input voltage. for particular diode rectifier needs some considerations like peak inverse voltage (piv), forward current, voltage rating, why because for producing dc current at the load side by conducting every half cycle of the input signal. fig . output waveforms during first half cycle diode d and d are forward biased and d and d will be off state. then current flowing through the diodes and it enters into load resistance rl. during negative half cycle diode d , d comes to forward biased and d , d will be in off state. the rectifier output waveforms are shown in fig. . international journal of recent technology and engineering (ijrte) issn: - , volume- issue- , january published by: blue eyes intelligence engineering & sciences publication retrieval number: e / ©beiesp doi: . /ijrte.e . c. lead acid battery fig . lead acid battery this battery made up of electrodes and electrolyte. for connecting electrolyte which operates the electrochemical reaction that provides electricity .in electrodes anode is negative terminal made up of solid lead and cathode is positive terminal made up of lead dioxide. in between cathode and anode one insulator / separator for avoiding short circuiting. the electrolyte is combination of water and sulphuric acid. it is one type of rechargeable battery and it stores energy in the form of chemical energy. when electrical energy is required this batter y converts chemical energy into electrical energy. the material required for this battery is lead peroxide (pbo ), sponge lead (pb), dilute sulfuric acid (h so ). iii. filter circuit fig . filter circuit this filter circuit is used for removing ac content in the output. this ac component completely removed and to get exact dc output. a filter circuit which removes the ac element in rectified circuit and allows dc element to reach the load .it is constructed by using two elements, i.e. inductor and capacitor. fig. shows the circuit of the filter configuration. inductor allows dc and blocks ac, and capacitor allows ac and blocks dc. here we are using capacitor filter so it allows ac and it blocks dc, it is known as shunt capacitor filter. the ac components are in grounded through the capacitor and remaining dc components collected at output side. fig. shows the complete block diagram representation of the proposed system. iv. results the battery of the proposed system is charged by solar energy and microcontroller is used to manage the smart water pump at different time slots which is automatic on / off control. in the manual irrigation based water system, the wastage of water is so high, so by using the proposed method the water wastage can be saved. in addition, the electricity is also saved because of the solar panels and battery regulatory system. the sequence of instructions has been given to the microcontroller which executes the program for different time slots to operate the water pump. the sensor is used to detect the water level and also sent this information back to the microcontroller. the program for the microcontroller is given below. fig . block diagram source code: #include<reg .h> #define ldata p sbit rs=p ^ ; sbit rw=p ^ ; sbit en=p ^ ; sbit relay=p ^ ; sbit sw =p ^ ; sbit sw =p ^ ; sbit sw =p ^ ; sbit sw =p ^ ; sbit b =p ^ ; void lcdcmd(unsigned char); void lcd_int(void ); void lcddata(unsigned char); void msg(unsigned char *d ); void msdelay(unsigned char); void delay (unsigned char); void main() { unsigned char i= ; relay= ; b = ; lcd_int(); lcdcmd( x ); implementation of microcontroller to control solar water pump at different time slots published by: blue eyes intelligence engineering & sciences publication retrieval number: e / ©beiesp doi: . /ijrte.e . lcdcmd( x ); msg("motor control.."); lcdcmd( xc ); msg("with time slots"); delay ( ); while( ) { if(sw == ) { lcdcmd( x ); b = ; while(sw == ); b = ; relay= ; lcdcmd( x ); msg(" motor on "); lcdcmd( xc ); msg(" slot "); for(j= ;j<= ;j++) { for(i= ;i<= ;i++) { delay ( ); } } relay= ; } else if(sw == ) { lcdcmd( x ); b = ; while(sw == ); b = ; relay= ; lcdcmd( x ); msg(" motor on "); lcdcmd( xc ); msg(" slot "); for(j= ;j<= ;j++) { for(i= ;i<= ;i++) { delay ( ); } } relay= ; } else if(sw == ) { lcdcmd( x ); b = ; while(sw == ); b = ; relay= ; lcdcmd( x ); msg(" motor on "); lcdcmd( xc ); msg(" slot "); for(j= ;j<= ;j++) { for(i= ;i<= ;i++) { delay ( ); } } relay= ; } else if(sw == ) { lcdcmd( x ); b = ; while(sw == ); b = ; relay= ; lcdcmd( x ); msg(" motor on "); lcdcmd( xc ); msg(" slot "); for(j= ;j<= ;j++) { for(i= ;i<= ;i++) { delay ( ); } } relay= ; } else { relay= ; lcdcmd( x ); lcdcmd( x ); msg(" motor off "); } } } void lcd_int(void) { lcdcmd( x ); lcdcmd( x ); lcdcmd( x e); lcdcmd( x ); lcdcmd( x ); lcdcmd( x c); } void msg(unsigned char *d ) { unsigned char j; for(j= ;d[j]!='\ ';j++) lcddata(d[j]); } void lcdcmd(unsigned char value) { ldata=value; rs= ; rw= ; en= ; msdelay( ); en= ; return; } void lcddata(unsigned char value) { ldata=value; rs= ; rw= ; en= ; msdelay( ); international journal of recent technology and engineering (ijrte) issn: - , volume- issue- , january published by: blue eyes intelligence engineering & sciences publication retrieval number: e / ©beiesp doi: . /ijrte.e . en= ; return; } void msdelay(unsigned char value) { unsigned char i,j; for(i= ;i<=value;i++); for(j= ;j<= ;j++); } void delay (unsigned char value) { unsigned char i,j; for(i= ;i<=value;i++); for(j= ;j<= ;j++); } battery solar panel display controller input panel charge controller load fig . hardware diagram of the proposed system fig . output image of proposed system at pump on condition fig . output image of proposed system at pump off condition fig. solar pv and iv curves for different irradiance levels figure shows the turn on condition of the proposed solar irrigation system. the different time slots have been given for the microcontroller to control the pump system automatically. according to the instructions at time : the system has to turn on and at time : it has to be turn off. from fig. it is clearly observe that at : time the water pump is turned on (see the motor is rotating). on the other hand, the fig. represents the pump turn off condition. as already said, at time : automatically the water pump got turned off can be seen in fig. . fig. shows the solar pv and iv curves at various irradiance conditions. implementation of microcontroller to control solar water pump at different time slots published by: blue eyes intelligence engineering & sciences publication retrieval number: e / ©beiesp doi: . /ijrte.e . v. conclusion this paper gives a result to supply water for irrigation, where electricity is a problem. advantages of this proposed system is that, no need of maintenance, no fuel requirement, gives long life, and easy installation. this project describes about automatic on/off of the pump at different time slots. the proposed system is very useful for farmers in difficult situations for energy crisis problem. a sensor is used which indicates when the soil needs water. automatic irrigation system is used to reduce the usage of water and reduces human work. solar panels gives energy needed to the water pump. by using solar panels, the energy crisis problem can be avoided. it requires less maintenance and just small attention for self starting. installation cost is more but it resolves more irrigation problems and gives long life. references . shatadru bipasha biswas , m. tariq iqbal “solar water pumping control using a low cost esp microcontroller” in , ieee canadian conference on electrical &computer engineering. . washima tasnin, pradyumna kumar choudhury “ deisgn and development of an automatic solar water heater controller” in , ieee . xiaoming cui, zhiweikou, yanjun qiao “water level control system for solar water heating engineering based on plc” in , ieee rd information technology , networking , electronic and automation control conference . prisma megantoro, fransisco danang wijaya “deisgn of solar water pumping system in urban residential building” in , international conference on control , electronic, renewable energy and communications . . nagi reddy. b, a. pandian, o. chandra sekhar, m. rammoorty, “design of non-isolated integrated type ac-dc converter with extended voltage gain and high power factor for class-c&d applications”. international journal of recent technology and engineering (ijrte), vol. , no. , jan , pp - . . prakhar kumar singh, omveer singh, smieee, shivam pandey “micro controller based water pumping system using solar energy” in th ieee uttar pradesh section international conference on electrical ,electronics and computer engineering. . b. sreewirote , m. leelajindakrairek “ deisgn and development of solar water pump” in ieee . nagi reddy. b, o. chandra sekhar, m. ramamoorty, “analysis and implementation of single-stage buck-boost buck converter for battery charging applications”; journal of advanced research in dynamical and control systems (jardcs), vol. , no. , april , pp - . . norlida buniyamin, k.n.y. salah, a.mohamed , zaimuddin mohammad “low cost solar water heater” in , international conference on electronic device, systems and applications . . nasifa binte yousuf, khosru m .salim , rafid haider, md. rajin alam, fatima binte zia “development of a three phase induction motor controller for solar powered water pump” in ieee. . l. sri sivani, nagi reddy b, k. subba rao, a. pandian, “a new single switch ac/dc converter with extended voltage conversion ratio for smps applications”. international journal of innovative technology and exploring engineering (ijitee), vol. , no. , jan , pp - . . g.ezhilarasan, p.balamurugan, anilkumar k , apoorva .y suvarchaka k “development of two stage buck –boost converter for solar pv based rural domestic water purifier” in ,international conference on power , control, signals and instrumentation engineering. . prasham shah , vineeta s.chauhan “ automatic solar submersible pump control for irrigation” in , international journal of advanced scientific research and management”. . nagi reddy. b, a. pandian, o. chandra sekhar, m. ramamoorty, “performance and dynamic analysis of single switch ac-dc buck-boost buck converter”. international journal of innovative technology and exploring engineering (ijitee), vol. , no. , feb , pp - . authors profile ms. m .pratyusha received her b. tech degree in electrical and electronics engineering from gokul institute of technology ,bobbili under jawaharlal nehru technological university kakinada in , m.tech degree in power electronics from pydah college of engineering under jawaharlal nehru technological university , kakinada in . she is currently working as assistant professor in electrical and electronics engineering department in gitam school of technology, bangalore campus. her area of interest are power electronics and drives. mr. b . nagi reddy received her b. tech degree in electrical and electronics engineering from mother teresa institute of science & technology, sathupalli under jawaharlal nehru technological university hyderabad , m.tech degree in power electronics from adam’s engineering college under jawaharlal nehru technological university , hyderabad in jan’ . he has done his phd fulltime from k l university and submitted phd thesis in june . he is currently working as assistant professor in electrical and electronics engineering department in vignana bharathi institute of technology, hyderabad. his area of interests are design & control of dc-dc, ac-dc & dc-ac converters, renewable energy sources, power electronic drives etc. mr. c .v. vijay kumar received his b.tech degree in electrical and electronics engineering from shaaz college of engineering and technology , moinabad, hyderabad from jntuh in , m.tech degree in power electronics and electrical drives from cvsr college of engineering , hyderabad from jntuh in . he is currently working as assistant professor in electrical and electronics engineering department in vignana bharathi institute of technology, hyderabad. his area of interests are power electronics & drives. myths_dec _bofst&s.pdf - - electric utility deregulation and the myths of the energy crisis by tyson slocum, research director public citizen’s critical mass energy & environment program www.citizen.org/cmep from the december “energy controversy” issue of bulletin of science, technology & society, vol. , no. , edited by steven m. hoffman. if the purpose of electricity deregulation is really to improve the quality of people’s lives by lowering the cost of a critical commodity, it has obviously failed, as demonstrated in every state which has chosen to deregulate. power companies, free from the oversight of state regulators, have quadrupled prices for montana industrial consumers, doubled prices in many northeast and new england states, and driven one of california’s utilities to bankruptcy. whereas consumers have been left to pay higher prices, energy corporations in deregulated markets have made record profits. it is clear that deregulation=s design was intended to benefit the energy industry far more than consumers. characteristics inherent to the electric utility industry effectively prohibit competition from occurring. these attributes, well-known to engineers and economists for decades, were glossed over by the energy industry as they orchestrated a national push to deregulate markets. their intention was to break free of the cost- based regulations which restricted their profits but guaranteed low prices and reliable service to consumers. in deregulation’s wake, blame has been foisted upon everyone from environmentalists to nimbyism (not in my backyard). but, it is clear that these and other myths are promoted to obscure the fact that fault lies with deregulation and its inability to provide electricity affordably or reliably. to fully understand how deregulation failed so miserably, we must examine the past. federal role prior to deregulation, electricity was supplied by regional monopolies that owned both the power plants and the transmission lines for the distribution of power. the california assembly, like their legislative counterparts in every other state, set the rate of return of profit for the utilities, and the state public utilities commission, like their peers across the country, planned for future power needs and helped ensure that rates were fair and based on the acost of service.@ although this system was often abused because of the enormous political power of the electric utilities and their ability to influence policymakers, it did keep in check the profiteering tendencies recently displayed in the deregulated markets of california and montana. whereas states controlled electricity, the federal government played an early, unintended role in encouraging deregulation. in response to the energy crisis of the s, congress passed the public utility regulatory policy act (purpa) in . purpa=s purpose was to wean america off foreign oil by encouraging - - alternative fuels for generating electricity. purpa requires utilities to buy power from independent power producers (mostly small generators, or ones using renewable energy sources) at a price approved by regulators. to achieve purpa=s objective of encouraging alternative energy supplies, regulators in many states approved high prices for long-term purpa contracts, which were passed on to consumers in the form of higher rates. at the same time, many utilities were building or just bringing on-line nuclear power plants. these reactors experienced tremendous cost overruns due to significant construction costs, expensive compliance with safety regulations, and significant waste disposal costs. the energy policy act of (epact) started to chip away at utilities= monopolies by expanding the federal energy regulatory commission=s (ferc) authority to order utilities to allow independent power producers equal access to the utilities= transmission grid. together, purpa and epact provided the first cracks in the utilities= monopoly. by the mid- s, large industrial consumers sought to escape the high costs of power in some parts of the country, such as california, that came as a result of building expensive nuclear power plants. at the same time, independent power producers such as enron were actively lobbying to be able to sell power to these big consumers. political pressure for deregulation mounted because the breakup of the $ billion dollar utility industry meant huge amounts of money could be made. no doubt, too, the meteoric rise of the dot.com industry in the early- and mid- s put pressure on the energy industry to increase their rates of return. enron, an important campaign contributor to the republican party and to president bush, lobbied for deregulation not only in california but at state legislatures across the nation and in congress. despite warnings from public citizen and other consumer groups, deregulation was heartily embraced by both political parties. under the clinton administration, the u.s. department of energy (doe) even wrote its own federal deregulation bill that it promoted unsuccessfully. the federal government got more involved in . seeking to further compromise the utilities= monopoly, ferc issued order , which was even more aggressive in its requirement that utilities open their transmission to independent producers. ferc's intent was to introduce competition at the wholesale level and to keep utilities from using their control of the transmission system to limit the entry of lower priced generation. but the primary result was to force states to deregulate, or else their regulated monopolies would get priced out by utilities operating in other states who had access to the transmission lines. order led to increased independent power generators, which overwhelmed most state=s ability to manage supply. this inability to plan for and manage supply prompted many states, including california, to fully deregulate their wholesale markets. in december , ferc issued order calling for the creation of regional transmission organizations (rtos), independent entities to replace state control and operation of the transmission grid. if the establishment of rtos is allowed to proceed, states will lose the ability to control electricity prices and - - reliability for their citizens, and corporations will have more free reign over the nation=s energy markets. the california debacle california=s utilities were initially skeptical of deregulation because of the high cost of power from their nuclear plants. but, the rise of technology stocks placed enormous pressure on the energy industry to achieve higher rates of return, as wall street threatened to move its capital elsewhere unless energy companies found a way around their tightly controlled profit margins. utilities ended up lobbing heavily for deregulation because they knew that their enormous political clout in the state legislature could shape deregulation=s outcome. in response to federal policies and industry pressure, states and the district of columbia passed legislation and regulations to deregulate their electricity markets between and (at the end of , had passed deregulation legislation). california was one of the first to jump in. the state=s extremely complex legislation, written primarily by california=s utilities, created a vast program for a vast market. it was wrangled over in a series of rapid-fire hearings, and rammed through the legislature in a process that took only weeks. it was unanimously passed and signed into law by governor pete wilson in the fall of . the legislation, written and supported by utilities, privatized their profit and socialized their risks. the most glaring example of this was the $ billion dollar consumer-funded bailout for the utilities= so-called stranded costs. stranded costs are essentially mortgage payments that the utilities make to cover their purchase of expensive boondoggle nuclear power plants. the utilities argued that the bailout was necessary because they would now be assuming marketplace risk, and the uncertainty of their future profits made the paying off of debts they incurred under regulation too burdensome. to accomplish this bailout, rates were artificially frozen for years, at what was then % above the national average cost of electricity. to date, ratepayers paid approximately $ billion through added costs to their electric bills to bail out the utilities. in , a coalition of consumer groups called californians against utility taxes sponsored a ballot initiative, proposition , which would have invalidated portions of the deregulation bill and prevented the utility bailout. the proposition would have required the utilities and their shareholders, not ratepayers, to bear the burden of the $ billion bailout. according to energy analysts at the california energy commission, if proposition had passed, residential power customers would have seen their energy costs fall between to percent. californiaís utilities spent more than $ million defeating proposition , compared to the $ million spent by consumer advocates (a similar grassroots ballot effort in massachusetts met an equivalent fate). the state=s deregulation legislation not only provided utilities with a bailout, but financed an international spending spree by the utilities using non-california subsidiaries. they purchased power plants and propped up the value of their stock through share buybacks. the stranded cost bailout provided them with capital, which they used to invest in other industries that they had been prohibited from entering under the regulated - - monopoly system. california=s utilities invested in telecommunications and other types of high-growth services that they planned to sell in conjunction with their sale of electricity. edison international=s largest unregulated subsidiary is mission energy, created in . mission=s revenues and profits did not take off until , when edison international transferred billions in consumer-funded stranded cost funds out of california. a public citizen analysis shows that mission energy, along with a few other smaller edison international subsidiaries, spent more than $ billion on non-california investments since december . in addition, edison international spent $ . billion on stock buyback programs since deregulation began. pg&e=s high-growth subsidiary, national energy group, has not been as forthcoming, electing not to disclose the purchase price of many of its recent acquisitions. information gleaned from several news reports reveals that since , pg&e=s purchases outside california and the pacific northwest total at least $ billion. pg&e spent over $ billion on its own stock buyback plans since the onset of deregulation. the consumer-funded bailout and the forays into new industries increased the utilities= earning potential and were strongly applauded by wall street. deregulation provided incentives for california=s utilities to sell their power plants to unregulated companies. they sold most of their fossil fuel plants at above the book value, making a significant profit. they retained their nuclear and hydro-power generation due to the extraordinary regulatory demands on these two generation sources. the deregulation legislation also transferred control over pricing of electricity generation to ferc. ferc ended cost-based pricing, and certified that each of the participants was now allowed to charge market prices—whatever price the market would bear. most of the corporations that bought the california utilities= power plants were from out of state and included virginia-based aes, north carolina-based duke, minneapolis-based xcel, and houston-based dynegy and reliant. eleven major companies, some of which simply buy and sell power without actually owning a single power plant, were selling electricity into the state=s auction, where electricity is bought and sold several times (in paper transactions) before it is actually delivered to consumers. why deregulation failed america has painfully learned what happens when deregulation is applied to an industry with inelastic supply and demand, high capital costs and prohibitively expensive transaction costs. with state government regulators no longer officiating wholesale electricity markets, the inherent characteristics of electric generation leads to excessive market power concentrated in a handful of energy companies. unlike other industries in the american economy, it is very difficult to foster competition in the electricity industry. electricity=s high overhead costs limit the number of players, since it requires hundreds of millions - - to build or buy a power plant. and building one is not easy, as construction can take years. constraints on siting power plants also inhibit competition because plants must be near power lines and meet minimum public health standards, since those using natural gas, oil or coal (as % of u.s. plants do ) produce harmful emissions. these constraints on power plant construction not only limit competition, but also the flexibility of supply to respond to changes in demand. unlike other products, electricity cannot be stored after it is produced; it must be immediately consumed. the capital constraints that restrict the entry of new generators into the market, therefore, limit the ability of supply to match demand. unless orderly advance planning is conducted to match supply with demand, shortages occur that drive up the price of electricity. and when the few corporations who control the power plants are left unregulated, there is tremendous incentive to withhold supply to create artificial shortages to drive up prices and profits. high transaction costs spent on household consumers for billing, repair and other customer services force electricity providers to operate on very narrow profit margins for each household consumer. large industrial customers, with their economies of scale, have lower transaction costs and pay far lower rates. in , for example, the average american household paid . cents per kilowatt hour for electricity, % higher than what the average industrial consumer paid ( . cents). households also paid % more than the average commercial consumer ( . cents) . although price discrimination exists under a regulated scenario, it becomes more severe under deregulation, forcing household consumers to incur higher costs by subsidizing commercial and industrial consumers even more. although these structural impediments to competition in electricity markets have been well known to economists for decades, policy makers at ferc and state lawmakers naïvely assumed that competition would magically appear once the wand of deregulation was waved. but they forgot, or ignored, the fact that the energy corporations who spent millions lobbying for deregulation were intent on exploiting these well- known problems. problems in california arose almost immediately once the state deregulated the wholesale market because the energy companies were now unaccountable to consumers. no longer forced to sell electricity for a set price to a geographically defined consumer base, energy companies used the inherent limitations in the electricity industry to leverage their market power to manipulate prices and supply. and, state regulators were powerless to stop them. the problem was that as soon as utilities break up their monopolies by selling their power plants, states cede regulatory authority over the electricity produced by those plants. under standard interpretations of the federal power act, states can regulate only the retail sale of electricity to end consumers (courts have ruled that wholesale sales of power are too fluid for individual states to handle, therefore classifying it as interstate sales subject to federal jurisdiction). under regulation, the utilities generated electricity at their own plants, delivered that electricity over their own wires, and sold the product to end consumers. regulating the retail price meant that states were, by extension, regulating the wholesale market, too, - - because the same company controlled both the wholesale and retail markets. the fact that utilities in deregulated states routinely sold their power plants for two or three times their book value should have been an indication that the purchasers of these plants clearly expected huge rates of return from their new investments. as prices in california=s wholesale market skyrocketed, the profits enjoyed by the unregulated power companies followed suit. price caps problem? deregulation proponents attempt to justify these failings by arguing that full deregulation removing all retail price controls to force consumers to pay the full wholesale price is the solution to america=s ills. they argue that price controls discourage adequate investment because power companies had no incentive to build new plants, as their rate of return was limited by the retail price caps. every state which has pursued deregulation has included retail price caps as part of their plan, to account for the utilities= so-called stranded costs, or debts the utilities accumulated building expensive nuclear power plants in the s and s. utilities in deregulated states argued that unless they were relieved of these debt burdens, they would be unable to compete in a deregulated market. state lawmakers agreed to a compromise, where consumers paid off the utilities= stranded costs in exchange for a rate freeze on consumers electric bills. once consumers were finished paying off the stranded costs, the rate freeze would end. if retail price caps are removed at a time of very high wholesale prices, the aconservation by force@ would prove to be not only politically unacceptable but would incorrectly assume that high prices are the result of a competitive market and should rightfully be passed on. prices in a deregulated wholesale market are high because the inelasticity of supply has led to excessive scarcity rents, deregulation=s price gougers: profits by the eight major energy corporations in california=s wholesale electricity market company (hq location) > profit ($ mil) > profit, $ mil (year dereg failed) % change profit st half > ($ mil) profit st half > ($ mil) % change west coast power (joint-venture between minneapolis-based xcel and houston-based dynegy) $ $ + % $ * $ * + % dynegy (houston) $ $ + % $ $ + % aes (virginia) $ $ + % $ $ - % williams (oklahoma) $ $ + % $ $ + % - - deregulation=s price gougers: profits by the eight major energy corporations in california=s wholesale electricity market duke (north carolina) $ $ , + % $ $ + % reliant (houston) $ $ + % $ $ + % enron (houston) $ $ + % $ $ + % mirant (subsidiary of atlanta-based southern co.) $ $ - % $ $ + % total $ , $ , + % $ , $ , + % * st half and figures are for nrg, parent company of west coast power, and a subsidiary of xcel. source: data compiled by public citizen from company -k and -q reports filed with the sec. helping energy companies dictate prices. for example, west coast power, the nrg subsidiary that owns california power plants for the parent company xcel, had after-tax profits of over $ million in the year prices for california electricity skyrocketed— percent higher than a year earlier in . a public citizen analysis of the eight major power companies controlling california=s market show that from to —the latter being the year that california=s deregulation scheme collapsed —their after tax profit jumped by $ . billion, from $ . billion in to $ . billion in . the trend continued in , with profits of nearly $ . billion in just the first six months, an increase of % over the record profits of the first six months of the year. these income figures, however, significantly underestimate the actual profits these companies made from their california operations. other than west coast power, which only owns power plants in california, the balance sheets of the other companies include results from all of their activities. because these corporations are not required to reveal the income they made in california, their profit numbers are dragged down by other sectors which lost money. state investigators, sifting through confidential wholesale price information, have calculated that these top energy corporations overcharged california=s utilities and ratepayers more than $ billion. ferc has acknowledged that billions in refunds are to be collected from these profiteers, and is overseeing ongoing settlement talks between the state and the corporations. as is the norm for the slow-footed ferc, a decision on the refund order is not expected until at least march . although it was clear that prices in california and the entire western market were wildly out of control in , president bush remained firm in his opposition to temporary price controls. the federal government had lone jurisdiction over california=s dysfunctional wholesale market. in a tense meeting with california governor gray davis in los angeles on may , bush failed to grasp the irony of his proclamation that electricity price controls would lead to amore serious shortages and even higher prices” made while sitting - - in a building wired to one of the only regions in the state immune from the power crisis: the socialistic, city- owned power of los angeles. while bush and ferc continued to play their “free market” ideological fiddle while california burned, the state=s utilities mounted huge losses as prices for the electricity they had to purchase on the wholesale market vastly exceeded the amount the state permitted them to charge consumers. the utilities= recent out- of-state shopping splurge had left them with insufficient cash on hand to cover their bills. and wall street was unwilling to provide reasonable bond financing for companies with few prospects for recovery. as a result, the taxpayers of california used the state=s impeccable credit to assume responsibility for purchasing electricity on behalf of the beleaguered utilities. the failure of the federal government to control wholesale prices forced california to spend $ million per day to purchase overpriced electricity from a handful of greedy companies. in light of the state spending tens of billions of dollars on electricity, even fellow republicans hopped on board the price control train. eight western state governors b half of whom are republicans b called on bush to enact price controls, and two gop members of the house of representatives with ratings at mid- percent from the american conservative union sponsored federal legislation to force bush to enact price controls. faced with the reality that their inflexible free-market ideology was a failure, bush and the federal government relented. since the federal government imposed round-the-clock wholesale price controls for the entire western electricity market in june , prices have dropped significantly, and california has experienced not one single rolling blackout. spot prices fell more than percent immediately after the price controls took effect. rising demand, environmentalists and nimbyism to blame? deregulation proponents have argued that california=s commitment to strong air quality standards prevented the development of adequate power plant construction. environmentalists blocked or slowed the construction of power plants, the argument goes, and nimbyism ensured that people’s unwillingness to live next to a power plant prevailed over the energy needs of the greater good. deregulation defenders claim that not a single power plant was constructed in california in the s. this claim, however, is false. california energy commission data clearly shows that new power plants, with the capability to generate , megawatts of electricity, or enough power for more than a million homes, came on line during the s. california has installed generation capacity of , megawatts - percent more than the summer peak demand of around , megawatts. the state=s problem was that about , megawatts of that capacity cannot be regulated by the state, thanks to deregulation. so the owners of the unregulated - - plants have incentive to intentionally shut down plants in order to artificially constrict supply to drive the price of electricity higher at their other, operational, plants. at the height of california’s electricity crisis, as much as , megawatts was offline for undisclosed reasons. according to the wall street journal, % more capacity was offline for undisclosed reasons in august compared to a year earlier. in deregulated markets, aundisclosed@ power plant shutdowns are a new phenomena: under state-regulated markets, power plant owners must continually disclose any problems which force a plant shutdown. williams, an oklahoma power marketing firm with a significant presence in california, was fined tens of millions of dollars by ferc for intentionally shutting down some of its power plants. the federal investigation found that williams intentionally withheld output at one of its plants so it could charge rates times higher at its neighboring power plant. the lack of accountability in deregulated wholesale markets allows corporations to manipulate critical commodities like electricity. these facts, that the state indeed had adequate capacity that was poorly managed by unaccountable corporations, forced the nation=s leading libertarian think tank, the cato institute, to draw the same conclusion in a july report: awe find little evidence to support the argument that environmentalists are primarily to blame for the [california deregulation] crisis.@ of course, increased investments in energy efficiency and renewable energy technologies would have liberated california from the current centralized, integrated energy system that is based on polluting gas and dangerous nuclear energy. whether a state deregulates or not, expediting the transition to a least-cost, environmentally sustainable energy system based on full exploitation of decentralized energy efficiency and renewable energy sources is the only path for a sustainable energy future. shared misery: montana and the looming crisis in other states a growing number of the other states which passed some form of deregulation legislation have taken heed of the powers of re-regulation. arizona, nevada, new mexico, oklahoma and west virginia have essentially repealed deregulation, others (arkansas, montana, new hampshire, oregon) are busy scaling it back, and most of those states that were on the fence are running away as fast as they can. of these, montana is the only state outside california that fully deregulated. in april , the governor signed montana=s deregulation law, which allowed the state=s industrial consumers the right to negotiate long-term contracts with alternative electricity providers beginning july . residential and small business consumers were not scheduled to deregulate until july . it was unclear what advantage montana lawmakers saw when they chose to deregulate. after all, montana had the seventh cheapest residential electric rates in the nation—owing to the state’s heavy reliance on the two cheapest forms of electricity generation, coal ( % reliance) and hydroelectric ( % reliance). access - - to abundant coal seams and rivers, combined with very low population density, allows for montana to export between % and % of the electricity it produces—providing residents with ample surpluses of electricity. regardless, montana resources, a copper smelting firm which requires large amounts of electricity to run its operations, was one of many industrial consumers which sought alternative suppliers to the state=s traditional monopoly, montana power. the mining company=s president, greg stricker, was an early and eager advocate for deregulation. he had argued that if montana failed to deregulate, companies like his would simply buy their electricity from power providers operating out of state. montana’s deregulation law left stricker’s company, along with other large industrials, free to negotiate long-term contracts with the provider of their choice. whereas the st year and a half was uneventful, in december montana power sold % of their generation assets to one company, pennsylvania-based ppl. just like in california, ppl operated as an unregulated monopoly as soon as the generation was split from the utility. ppl spun off a montana subsidiary which operated the plants, and in the year and a half since they have presided over montana=s deregulated electricity market, they have enjoyed after-tax profits of $ . million. these profits have been fed from wholesale prices which jumped as high as % in a matter of weeks. many industrial customers, forced to renegotiate their contracts during a time of high prices, could not afford to continue operating. unable to afford their electric bill, dozens of industrial plants closed their doors, laying off more than , montanans in the last year. meanwhile, stricker’s copper smelting operation was also forced to close, laying off employees. in march , stricker—one of the architects of montana=s deregulation law—announced to the montana legislature that aan immediate return to full regulation of montana=s electricity market is the only way to ensure that all montanans receive reasonably priced electricity now and in the future.@ in response, the legislature in june passed legislation delaying residential deregulation for years, and allowed industrial consumers who were stuck with expensive ppl contracts to nullify them. but in order to appease ppl, the state of montana has guaranteed the contract for five years at $ million, necessitating a minimum % rate increase for the state’s consumers. agitated by the size of this bailout—after all, ppl enjoyed tremendous profits in the state=s deregulated market—two state representatives spearheaded a successful grassroots ballot initiative to overturn this bailout. reps. michelle lee and chris harris have qualified their referendum to repeal montana’s deregulation bailout for the november election. while other states’ experiences are not nearly as dramatic as california’s and montana’s, serious problems lurk just around the corner if the states continue pursuing deregulation. sharing a border and high wholesale prices with california, nevada repealed its deregulation law in april , forbidding the completion of the sale of the state utilities’ generation assets in the process. arkansas pushed back their deregulation state - - date by a year in response to the california crisis. in arizona, a judge ruled that deregulation violated the state’s constitution, placing that state’s restructioning on hold. in april , new hampshire’s state government delayed the start of deregulation for several years. new mexico, bowing to the fears that they could end up like california, delayed the start of their deregulation for five years. in may , oklahoma placed their deregulation laws on hold indefinitely. oregon voted in june to delay deregulation for five months. in west virginia, the legislature has so far failed to implement the necessary bills to enable the state’s public service commission to proceed with deregulating the state’s electricity market. of those states that are left, there are no deregulation successes. of the states that passed deregulation legislation, only a handful (like connecticut) actually changed their energy supply systems. and since these few are participants in a broader power pool with both wholesale and retail price controls, their system does not resemble a deregulated marketplace. some places, such as washington, dc, negotiated low-priced long-term contracts as a condition of the sale of the utility’s power plants. but when the contract expires in , dc will have no leverage to negotiate another favorable contract. other “success” stories like pennsylvania, retain strict retail price caps. in addition, all but one of the state’s utilities still retain their generation assets, meaning the state continues to have a regulated monopoly. but the retail price caps are set to be removed beginning in , at which point the state’s consumers will be subject to an unregulated monopoly (it is significant to note that the one pennsylvania utility which divested its generation assets has petition state regulators for a rate increase, as it can no longer afford to purchase overpriced electricity in the wholesale market). britain=s deregulated electricity market, often touted in america as a successful attempt, has been rife with similar problems. the office of electricity and gas markets found last year that collusion and price manipulation of britain=s power pool was the norm. this uncompetitive behavior has translated into british consumers paying, on average, % more for their electricity than their american counterparts. should we be so surprised? deregulation’s failures are strikingly similar to other recently-deregulated industries with features comparable to the electricity industry. the telecommunications act of was supposed to usher in an era of competition and choice. instead, the american economy is saddled with a dozen telecom multi-billion dollar bankruptcies, not to mention contracting revenues, highlighted by the $ . billion fiscal year loss reported by jds uniphase in july . meanwhile, . % of phone lines continue to be controlled by the old monopolies. since congress relaxed regulations for the cable tv industry in , consumers are paying percent more for the price of basic cable, and consolidations have resulted in six corporations presiding over % of the market. in a series of incremental deregulation orders, residential natural gas customers are reeling under high - - prices. the federal government once enforced tight price controls on interstate natural gas pipelines. but with market pricing now firmly in control, the handful of pipeline and wholesale market traders dictate the price to residential consumers. since the wellhead decontrol act, natural gas wholesale prices have actually fallen. but the price at which natural gas is sold to residential consumers has skyrocketed, while prices sold to industrial and commercial consumers has fallen substantially. for most economists, such overt price discrimination clearly indicates the existence of a noncompetitive market. just like these capital-intensive and transmission-constrained phone, cable and natural gas industries, true competition in deregulated electricity markets has not materialized. solutions to protect consumers the flaws in the cost-based rate system pale in comparison to the damage wrought by price gouging and unreliability under market-based rates. most states with looming deregulation deadlines have made the prudent move to re-regulate. but for millions of american household and business consumers in states exposed to deregulation, the damage has been done. for those states, re-establishing regulatory authority over deregulated wholesale markets will be an expensive, but crucial step. it is important to note that those states that have experienced severe market power abuses in their wholesale deregulated markets— california, new york and montana—have established state power authorities which have the ability to buy or build power plants. this solution—leveraging public control over generation—is crucial in order to return accountability to electricity markets. encouraging municipally owned and controlled power is the key. across america, the , communities with publicly owned power pay far less than those customers served by corporations. los angeles and the other california public power communities were completely immune from the state’s energy crisis because the city power companies had no incentive to price gouge their owners, who also happen to be their customers. a federal role also exists. increased transparency and swift enforcement of market rules, not less as is the trend under deregulation, is the only guarantee of producing markets accountable to consumers. lawmakers, rushing to correct deregulation=s failures, must exercise diligence not to make matters worse. a prime example is illustrated in the calls for a afederalization@ of america=s transmission grid. the failure to expand transmission capacity from a system designed to handle small loads between regional regulated monopolies to one capable of handling deregulation=s frenzied pace of trading is one valid explanation for supply constraints. but, prescribing both broad regulatory (through rtos) and eminent domain authority for the federal government without addressing the utilities= monopoly control over transmission is a misdiagnosis. nondiscriminatory, reliable access to the transmission grid at affordable prices can only be provided by consumer-owned, non-profit transcos. can electric utility restructuring meet the challenges it has created?, by richard a. rosen. the tellus institute, november , page - . - - rosen, page - . rosen, page . u.s. department of energy, energy information administration this figure was widely reported in the press after the california deregulation bill’s passage, for instance, in financial times , july , . public citizen verified the amount for the bailout for the october report, california dreaming: the bailout of california’s nuclear industry. to do so, we used information provided by the nuclear regulatory commission monthly operating reports: december and data from the california public utilities commission (cpuc), including cpuc decisions n. - - , n. - - , - - , and - - . the cpuc’s office of ratepayer advocate also provided assistance. herbert chao gunther and joe therrien, “an overview of ab , the california utility deregulation bill,” public media center, summer . the san francisco examiner , tuesday, july , , “war of words escalates over prop. ”. ben arikawa, ruben tavares, “preliminary analysis of the utility rate reduction & reform act,” california energy commission, electricity analysis office, july , . wall street journal, “california backs into the future,” editorial, november , . public citizen analysis of data from edison international filings with the securities and exchange commission. public citizen analysis of data from pg&e filings with the securities and exchange commission. u.s. department of energy, energy information administration, electric power annual. u.s. department of energy, energy information administration, annual electric utility report. scott hempling, electricity law: current topics . exhibit . , financial statements of west coast power , to nrg energy’s -k filed with the u.s. securities & exchange commission on march , . los angeles times , “regulators plan energy rebate settlement” by ricardo alonso-zaldivar, july , . houston chronicle, “northwest electric refunds denied”, september , . los angeles times , “bush blunders into equal footing with davis,” by george skelton, may , . san diego union-tribune, “gov. davis loses balance while straddling sides in energy crisis,” by bill ainsworth, april , . rebecca smith, “governors seek caps on prices for electricity,” the wall street journal, feb. , . mark golden, “electricity prices in west fall on ferc controls,” the wall street journal, june , . california energy commission, "power plant projects before the california energy commission since ," january , . california independent system operator. chip commins and rebecca smith, “for power suppliers, the california market loses its golden glow,” the wall street journal, jan. , . rebecca smith, “california seeks curbs on power firms,” the wall street journal, june , . jerry taylor and peter vandoren, “california’s electricity crisis: what’s going on, who’s to blame, and what to do,” july , . pam silberstein, “july retail wheeling report”, national rural electrical cooperative association. jan falstad, “butte exec seeks return to electricity regulation”, billings gazette, march , . u.s. department of energy, energy information administration. falstad. associated press, “democratic legislative leaders defend lawsuit,” july , . u.s. department of energy, energy information administration. steve rosenbush and peter elstrom, “ lessons from the telecom mess,” businessweek, august , . bruce orwall, deborah solomon and sally beatty, “the bigger picture: why the possible sale of at&t broadband spooks 'content' firms,” the wall street journal, august , . public citizen analysis of energy information administration data. microsoft word - lady marianne e. polinga abstract—this study was an investigation on the suitability of lahar/hdpe composite as a primary material for low-cost small- scale biogas digesters. while sources of raw materials for biogas are abundant in the philippines, cost of the technology has made the widespread utilization of this resource an indefinite proposition. aside from capital economics, another problem arises with space requirements of current digester designs. these problems may be simultaneously addressed by fabricating digesters on a smaller, household scale to reach a wider market, and to use materials that may accommodate optimization of overall design and fabrication cost without sacrificing operational efficiency. this study involved actual fabrication of the lahar/hdpe composite at varying composition and geometry, subsequent mechanical and thermal characterization, and implementation of statistical analysis to find intrinsic relationships between variables. from the results, lahar/hdpe composite was found to be feasible for use as digester material from both mechanical and economic standpoints. keywords—biogas digester, composite, high density polyethylene, lahar. i. introduction ne of the current thrusts in worldwide research is the use of renewable energy. the role of materials engineering here is to provide the means for optimum utilization of resource through the development of advanced materials in equipment designs. the limiting factor remains as to the widespread acceptance of the technology, which hinges primarily on both financial and logistical economics. there are two pressing problems that pose challenges to our country’s stability: energy crisis and pollution. clearly, the natural resources for conventional energy have been depleted and its continuous supply in the future remains uncertain. pollution can be generally attributed to the increasing number of people living in the metropolis, the declining capacities of landfills, and the extreme difficulty of finding new location for dumpsites. approximately metric tons of garbage is generated everyday with only % out of this volume being collected [ ]. l. m. e. polinga is with the department of mining, metallurgical and materials engineering, university of the philippines (phone: - - loc ; e-mail: matls.engr@gmail.com or lepolinga@up.edu.ph). c. c. mercado was with the department of mining, metallurgical and materials engineering, university of the philippines . c. a. polinga is with cavite state university, philippines . (e-mail: capolinga@yahoo.com). biogas technology is the only alternative technology that allows us to address these problems. the biogas technological process was developed as a means of obtaining fuel gases (ch , co, h s) from the fermentation of organic materials. these reactions occur by the actions of microorganisms under anaerobic conditions, as promoted by a device called the biogas digester [ ]. an agricultural country such as the philippines has abundance on sources for organic materials, in piggeries, farms, etc., but the technology cannot penetrate a wider market due to economic constraints. also, current studies on the engineering of the digester design required either reinforced concrete or pvc as construction materials, which have proven rather costly for extensive application. a biogas digester (fig. ) is a device that provides the anaerobic condition in the biogas technological process. present biogas digesters use reinforced concrete, cement, and coco lumber as construction materials. it should have excellent mechanical properties and a thermal capacity of - o c. it should be lightweight and resistant to wear and corrosion. it should be chemically stable to ensure that it will not interfere with the anaerobic digestion [ ], [ ]. it should be environment-friendly and have minimal cost. fig. fixed-dome biogas digester design [ ] lahar is a pyroclastic deposit that is mainly composed of silicon dioxide (sio ). although it is associated with disaster, studies reveal its good quality in terms of compressive strength per unit weight. it has a . to . ratio of al o to sio that indicates suitability for element addition. about % to % of cao is also present in lahar that implies its capability as a binding material [ ]. however, its principal drawback is its disposition to a catastrophic fracture in a brittle manner with very little energy absorption. fortunately, creating a composite material can significantly improve the material’s fracture toughness. high density polyethylene has greater stiffness, rigidity, improved heat resistance, and formation and evaluation of lahar/hdpe hybrid composite as a structural material for household biogas digester lady marianne e. polinga, candy c. mercado, and camilo a. polinga o world academy of science, engineering and technology international journal of materials and metallurgical engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , m at er ia ls a nd m et al lu rg ic al e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/formation-and-evaluation-of-lahar/hdpe-hybrid-composite-as-a-structural-material-for-household-biogas-digester/ http://scholar.waset.org/ - / increased resistance to permeability as compared to other polymers. this study, in effect, focuses on developing a potential for the wider acceptance of household biogas digesters through the optimization of both technology and economics by applying inexpensive, readily available, and easily fabricated materials for construction. fabrication of a prototype model of the lahar-hdpe based biogas digester was not covered in the study. ii. methodology the experimentation design employed in this study considered lahar: hdpe mass ratio and sample thickness as the working variables. a. preliminary investigation preliminary investigation of the raw materials was done to provide elementary information on the state and quality of lahar samples and virgin hdpe. the lahar samples were processed with metallographic sieves to achieve a reported particle size of % passing microns. hdpe pellets were supplied by jg summit petrochemicals, inc. b. sample fabrication the manufacturing technique used was the compressive melt method [ ]. in this method, the raw materials were mixed in a two-roll mill for minutes at o c. the molten mixture was molded at o c using a shinto compression molding machine with a pressure at the cylinder side of kg/cm . fig. presents the schematic diagram for the processing of samples. c. characterization and evaluation characterization of the experimental products applied four ( ) analytical techniques: ( ) sem was used to reveal the microstructure; ( ) utm (astm e ) measured the tensile strength; ( ) three-point bend flexure test (astm d - ) measured the flexural strength; and ( ) sdt-tga measured weight changes as a function of temperature, and consequently determined the thermal stability of the composite. fig. diagram of the compressive melt method used to fabricate lahar/hdpe composite since the study offered a technology that will help mitigate pollution and solve our energy crisis, the production cost and environmental implication of the over-all process were also evaluated. statistical analysis was done to determine if there was significant interaction between the effective variables and the physical, mechanical, and thermal properties of the composite. from the results obtained after analysis and evaluation of the experimental product, the effectiveness of lahar-hdpe composite was determined by comparing the properties exhibited by the fabricated material to the requirements of the structural design. iii. results and discussion result of the study showed that the lahar-hdpe composite could be effectively utilized as structural material in constructing a small-scale biogas digester. lahar-hdpe composite passed the required specifications of the digester design. a. physical properties the composites were generally black in color with a porous surface. fig. presents a summary of the physical properties for the mm thick samples. treatments with higher amount of lahar component show a more intense dark color. warping occurred due to localized couple of tensile and compressive stresses. it is especially displayed by mm thick samples and is mostly negligible for mm thick samples. world academy of science, engineering and technology international journal of materials and metallurgical engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , m at er ia ls a nd m et al lu rg ic al e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/formation-and-evaluation-of-lahar/hdpe-hybrid-composite-as-a-structural-material-for-household-biogas-digester/ http://scholar.waset.org/ - / fig. effect of mass ratio to the surface porosity, warping, and color intensity of the lahar/hdpe composite b. microstructure and mechanical properties the morphology of the composite in question, which is the interaction between lahar and hdpe, was examined under the sem. the micrograph revealed a weak adhesion for samples in which there is a large difference in the relative constituency (fig. ). fig. fractured surface of the lahar/hdpe composite (arrows indicate lahar crystals) samples with larger relative amount of hdpe exhibit higher tensile strength. the composite gave a mean uts of . mpa. mass ratio however is not statisically significant at % confidence level. fig. effect of sample thickness to tensile strength fig. effect of sample thickness to flexure strength fig. sem micrograph of lahar/hdpe composite that failed due to brittle fracture ( x) flexure and tensile tests revealed that mm composite have notable mechanical strength as compared to its mm counterpart (figs. and ). this performance was explained by the fact that smaller samples consequently had smaller number of defects. treatments with thickness of mm gave a mean of . mpa while cm thick samples gave a mean of . mpa. analysis of variance reveals that sample thickness is a significant factor of tensile and flexure strength at % confidence level. c. thermal properties the melting and degradation temperature of the different samples were extracted from the differential thermal diagram. from the thermal analysis curve, the thermal stability against composition of the composite was deduced. the melting and degradation temperature of the different samples were extracted from the differential thermal diagram. the composite was found out to be thermally stable with a capacity of up to o c ± o c. world academy of science, engineering and technology international journal of materials and metallurgical engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , m at er ia ls a nd m et al lu rg ic al e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/formation-and-evaluation-of-lahar/hdpe-hybrid-composite-as-a-structural-material-for-household-biogas-digester/ http://scholar.waset.org/ - / (a) (b) fig. effect of (a) mass ratio and (b) sample thickness to the thermal properties of the composite d. engineering analysis the experimental results were compared to the material specifications required by the household biogas digester design, and are presented in table i. economic analysis has shown that a lahar-hdpe digester would cost around php . /m , as opposed to a concrete-based unit which required php /m to construct. table i design specifications of a small-scale digester and properties of lahar-hdpe composite parameters requirement lahar/hdpe composite strength, mpa ksi or . mpa . mpa (mean) thermal capacity o c to o c up to o c ± o c weight relatively lightweight kgs chemical resistance excellent excellent corrosion resistance excellent excellent environment friendly yes yes low cost yes yes iv. conclusion it can be concluded that good quality lahar-hdpe composite can be fabricated using the compressive melt method. the lahar-hdpe composite exhibited good mechanical properties and thermal stability. the tensile and flexure strength of the composite is significantly affected by the sample thickness. lahar-hdpe composite-based biogas digester is more cost-effective and has a lower production cost compared to the presently available concrete-based biogas digesters. the process and the product do not pose any threats to our environment. the fabricated lahar-hdpe can therefore be used as structural material for household biogas digester. based on the inferences of this investigation, the author recommended lahar-hdpe composite be utilized in constructing household biogas digester. seeing the potential of this technology, it is also recommended that this innovation be promoted to help alleviate our economy and mitigate our problems on environment degradation. acknowledgment the author wishes to thank the department of science and technology, jg summit petrochemical, and the university of the philippines for supporting this research endeavor. references [ ] polinga,c.a. optimization of physical parameters of contained rapid composting system university of the philippines, los baños. . [ ] yeong, hee joo. anaerobic digestion of solid wastes. . [ ] polinga,c.a. et. al. how to construct a dsac model biogas plant. pamphlet series on appropriate technologies. cavite state university. . [ ] celzo. m.s.i. study of the compressive strength and unit weight of specimens made from lahar sand and lahar sand-derived materials. university of the philippines, diliman. . [ ] basilia. b. a., hybrid formation and properties of polymer layered silicate nanocomposites. university of the philippines, diliman, quezon city. world academy of science, engineering and technology international journal of materials and metallurgical engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , m at er ia ls a nd m et al lu rg ic al e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/formation-and-evaluation-of-lahar/hdpe-hybrid-composite-as-a-structural-material-for-household-biogas-digester/ http://scholar.waset.org/ - / wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ sociology and anthropology ( ): - , http://www.hrpub.org doi: . /sa. . urbanisation and energy crisis: the case of lagos state lai olurode , wakeel isola ,*, demola adebisi department of sociology, faculty of social science, university of lagos, lagos state, nigeria department of economics, faculty of social science, university of lagos, lagos state, nigeria copyright© by authors, all rights reserved. authors agree that this article remains permanently open access under the terms of the creative commons attribution license . international license abstract the study employed in-depth interviews to collect information from households living in the upper class areas of magodo, lagos and those living in the slum areas of iwaya. the locations were chosen purposively. the responses from the interviewees indicate that both high and lower neighbourhoods in lagos experience epileptic power supply and that resident have learnt to cope with the power situation using diverse strategies of coping. the various responding mechanisms adopted by those consumers, however, are based on financial capabilities. from the interviews conducted, it was apparent that both high income and low income families tend towards the use of generators. however, they also make use of lamps and solar energy in few cases. also, both classes of families use gas stoves as an alternative to electric stoves for cooking. and occasionally they use kerosene stoves. planning ahead was a recurring feature among the households, which indicated how they prepared for the eventualities of power outages. the study concludes that the way out of the problem is to fully implement the power sector reforms. in addition, there is the urgent need to diversify the sources of generating electricity in nigeria and mitigate the problem of corruption, which has been the bane of the sector over the years. keywords urbanization, megacity, epileptic power supply, lagos state . introduction a visit to a typical urban scene in most of the third world countries will bear an eloquent testimony to a breakdown of municipal governance. it is a common experience that frequent power outage, poor road network, slums and mountains of refuse and other signs of urban decay have become the hallmarks of many of these urban cities. in spite of this, migrants have continued to flow in without regard for the huge pressure on infrastructure and social services. that urbanization poses a threat to social services in third world cities is therefore not in doubt. perhaps, it is not a mere coincidence that a high rate of urbanization has spurred the development of some megacities across the globe. according to the united nations [ ], there were megacities globally and this number is projected to rise to by . of the world’s megacities in , are located in the less developed regions. china alone according to this study had six megacities in , while india had five. africa can only boast of three countries that have attained the status of a megacity namely kinshasa, cairo and lagos. the growth and development of the megacities are expectedly, not without some challenges such as access to electricity, which has been a source of concern in less developed countries. legros et al, [ ] admit that about . billion people lack access to electricity in the less developed countries (ldcs). in relation to other regions of the world, the study state that million and million people are without access to modern fuels and electricity in sub-saharan africa. it further stated that less than million people in east asia and the pacific lack access to electricity. about % of the people are without electricity access in developing countries. % of them are in sub-saharan africa, compared to the % in ldcs. this means that even though access to energy varies widely across ldcs, energy access is far lower in poorer developing countries than in richer ones legros et al, [ ]. the implication of this is also that a large percentage of the population is without access to modern fuels. according to usaee [ ] in , out of the . billion people who lack access to electricity, over million are in sub-saharan africa, while over million come from india alone. however, the world economic outlook weo, [ ] maintains that about % of the world population (i.e. . billion people) lack access to electricity in . in nigeria, while electricity access has grown from . % in to . % in world bank, [ ], the problem of urbanization has continued to play down the impact of such growth over time. currently, out of the million of nigeria’s population, about million are without access to electricity. the national electrification rate in nigeria as at the end of was %, out of which urban urbanisation and energy crisis: the case of lagos state electrification rate was %, while rural electrification rate was %. similarly, in terms of biomass for cooking, the population relying on biomass in nigeria is million; % of this relied on the traditional use of biomass in weo [ ]. it means that generally in nigeria, access to modern energy is very low and the energy crisis is very high. the low rate of rural electrification in nigeria and inaccessibility to modern energy has made the rural-urban migration a necessity and an irresistible trend. this has further exacerbated the problem of urbanization and deepened the energy crisis in the urban areas, especially in lagos state. expectedly, the fact that urbanization has occurred arbitrarily in lagos has exerted a severe strain on existing infrastructure and contributed immensely to energy crisis in the state. resolving this urban growth problems vis-à-vis those of the energy crisis should be of paramount interest to nigeria; especially lagos state. this would help to fast-track the goal of achieving sustainable development in the state and improve the living conditions of the citizenry. against this background, this study seeks to evaluate the pushing effects of urbanization and unstable electric power supply on the growth of the lagos state economy. the motivation for the study stems primarily in the realization that poor electricity supply in the face of a rising urbanization demand could pose a devastating problem on growth. hence, the need to offer suggestions that can ameliorate the challenges. the relevant questions this study addresses include: is there any gap between the secondary energy supply such as, electricity and the requirements of the city? what are the strategies employed to cope with the problem of the electricity gap on the households? these questions will be analyzed within the context of power sector reforms in nigeria for necessary policy options. the rest of the study is organized as follows: section presents the stylized facts on the population of lagos state and electricity sector in nigeria, with special reference to lagos. review of relevant literature is presented in section . sections and focus on the methodology and results of the study. stylized facts on the population and electricity infrastructure in lagos state lagos state population and trend lagos, the th largest city in africa, has continued to experience an unprecedented growth in its population since . the national bureau of statistics (nbs) [ ] and national population commission [ ] put the population of lagos at , and , , in and , respectively. however, lagos achieved the status of a mega city in , with a population of , , . it has been projected that by the population will be about , , . this is trend is shown in figure . electricity in nigeria the electricity industry began in nigeria towards the end of the th century. the first generating plant was installed in lagos in by the colonial government and was managed by the public works department (pwd). in , the government passed the electricity corporation of nigeria ordinance no. . thereafter, several other legislations were enacted. these include the niger dam authority (nda) act of parliament of and the decree of june , by which the national electric power authority (nepa) was established. nepa was mandated to maintain an efficient, coordinated and economic system of electricity supply to all parts of nigeria. the law made nepa a monopoly by making it the sole body responsible for the generation, transmission, distribution and marketing of electricity. figure . trend of population of lagos state sociology and anthropology ( ): - , as a state-owned establishment, nepa was inefficient in service delivery, innovation and management. in an effort to reverse the poor electricity tale, the government decided in to embark on a comprehensive review of the sector, in terms of policy and institutional reforms. nepa and its successor company, the power holding company was corporatized and commercialized and this enabled the organization to review its tariffs upward without an appreciable increase in quantum of electricity generation. the most radical change came with the passage of the electric power sector reform act (epsra) in which made nigeria to effectively join the global restructuring and deregulation trend. under the reform, nepa/phc was broken into companies, comprising generators, distributors and one transmission company. in addition, the deregulation of the sector again opened up the market for the independent power producers and other private initiatives by other stakeholders including state governments, such as lagos state. current situation with lagos state electricity lagos state is the only nigerian state with a very aggressive ministry of energy and mineral resources. the establishment of this ministry was borne out of the fact that the lagos state government has in recent times embarked on several energy-related projects which range from independent power plants to solar energy projects and to public lighting largely inspired by the power sector reform. it also covers household energy and emissions calculators lagos state electricity board [ ]. the independent power plants (ipps) set up by the state are designed to improve electricity access by taking the state off the national grid. the state previously operated ipps at akute, lagos island and alausa. it has so far installed . mw, connected to more than load centers and supplied over km of public lighting. according to the lagos state electricity board, the ipps have helped to drastically improve the electricity supply reliability from % to about % on the average, making them more effective in providing better service to the populace. the state also currently has two additional ipps: the mainland power and the peninsula integrated power project. the two ipps have a combined capacity . mw. to ensure that the state sustains and improves on its present energy supply condition, it embarks on a state-wide energy audit with the aim of collating a comprehensive database of the real-time power demand of lagosians and that of the installed capacity from the grid. consequently, over , residential, industrial and commercial locations were audited at the end of and the exercise revealed that only a little above % of electricity demand by the state was met by the national grid. the state discovered over , generators in the audited locations, meaning that each location has at least generator. this translated to the consumption of about , litres of diesel per day and resulted in about lbs carbon emission per day. in order to curb the volume of emissions arising from electricity consumption in the metropolis, the lagos state electricity board (lseb) recently took a stand in favor of renewable energy. the office of the lseb in ikeja currently generates about % of its energy from a kwp solar farm installed within its premises lseb, [ ]. nigeria only generates less than mw for a population of million. incidentally, lagos state accounts for % of the total electric supply for industrial, commercial and domestic demands as characterized by the power supply companies, thus highlighting the picture of the problem. for example, in , the demand for electricity was approximately mw in the eko disco zone alone eko disco [ ]. in , the distribution capacity of both ikeja and eko discos was put at mw and mw respectively, giving a combined total of mw. also, the customer population of each of the discos was put at , and , respectively the nigeria energy support programme (nesp) [ ]. a summary of this picture is depicted in table . table . electricity supply gap in lagos state in megawatts (mw) source: nigeria energy support programme ( ) and own computation. dc (distribution capacity). mw (megawatts). urbanisation and energy crisis: the case of lagos state . literature review the relationship between urbanization and energy related crisis has received a scholarly attention in the literature. parikh and shukla [ ] examined the role of urbanization, energy consumption and green-house emissions in economic development. the study employed a multiple regression framework using a cross section of data to analyze the indicators of urbanization and other economic indicators. it was observed that aggregate energy consumption increases with urbanization. by the same token, shahbaz and lean [ ] analyzed the relationship among urbanization, industrialization and energy consumption in tunisia between and . it employed the autoregressive distributed lag (ardl) bounds testing approach as well as the granger causality tests to analyze the secondary data which cover the variables of interest. findings from the study suggest that a bidirectional causality exists between industrialization and energy consumption. additionally, it was observed that urbanization intensified the volume of energy consumption in tunisia over the period studied. the study, thus, called for the examination of the nexus between industrialization and urbanization to fast-track the development process. similarly, shen et al [ ] investigated the relationship among urbanization, sustainability and energy utilization in china. in the study, the trend among the variables was analyzed and it was observed that a positive relationship between growth, urbanization and energy demand in china existed. the study therefore concluded that if urbanization grows faster than predicted, china might face a long term resource shortage. in the same vein, wang [ ] analyzed the impact of urbanization on china’s energy consumption. the study defined two types of energy use in the urbanization process as residential energy consumption (rec) and production energy consumption (pec), observing however that growth enhanced by urbanization increased rec while pec was consistently reduced between and in china. certain other studies have also focused on the correlation between urbanization and energy consumption, where it was observed that a positive relationship exists between urbanization and energy use. for instance, jones [ ] conducted a cross-sectional study on ldcs and observed that urbanization significantly increased energy use. imai [ ] empirically observed that urbanization contributed to energy crisis in china. zhou et al [ ] identified and analyzed three energy-consuming sectors that are strongly linked with urbanization as residential, industry and transportation. the study fundamentally observed a negative relationship between energy demand and urbanization. ewing and rong [ ] observed that more urban areas had very reduced energy consumption per-capita in canada. similarly, other studies have focused on the causal link between urbanization and energy consumption. a study by liu [ ] revealed that urbanization has a positive causal effect on energy consumption in china. fan and xia [ ] found out the same results in china. mishra et al [ ] observed that short term causality exists between energy consumption and urbanization in the pacific island countries. in another study by halicioglu [ ], it was observed that causality runs from prices, urbanization and gdp to energy consumption in turkey between and . world bank [ ] report on african urbanization revealed that african countries lag behind their peers in developing countries in terms of infrastructure provision. access to electricity reaches only percent of african citizens, when compared with the percent in other developing countries. average power consumption is kilowatts per capita, or percent of that in the rest of the developing world. african firms report losing percent of their sales because of frequent outages. this figure jumps to percent for informal firms. while private firms are eager to explore the potential of african growing markets, lack of infrastructure constitute major obstacles to private investment. according to arnulf and jayant [ ], rapid migration and natural population growth in cities can overwhelm the provision of basic urban services, particularly for the poor urban dwellers. several hundred million urbanites in low and middle income nations lack access to electricity and are unable to afford cleaner, safer fuels, which result in-significant adverse consequences for human health and local air quality. supporting sub-saharan african municipalities with sustainable energy transitions samset [ ] showed that total population in south africa is growing at percent per annum. the population is predominantly urban, and currently percent of the approximately million total population live in towns or cities, of which percent are located in the large metros. this is expected to increase to percent by . cities and towns produce percent of south africa’s gross value added (gva), and home to around two-thirds of the population. with the predominantly urban growth, south africa has not been able to address the challenges of poverty levels substantially. the main energy dimensions of this include thermally uncomfortable housing and lack of access to modern affordable energy sources. poor households spend percent, on average, of their income on basic energy needs, as opposed to or percent for wealthier households. in south africa, the modern energy focus has been on electricity provision. the report also showed that national electrification rate levels are percent when compared to percent in . however, a significant number of households remain without electricity connection. the current electrification backlog is . million for the informal and . million formal households. simon and innocent [ ], in their review of literature of the nexus between urbanization and energy demand in ghana revealed that energy for lighting in urban ghana is sociology and anthropology ( ): - , predominantly electricity. though available to all urban dwellers, it is inaccessible to urban poor who still depend on candles for lighting or get connected illegally from their neighbours. the supply of electric power is also very unreliable, marked by persistent power fluctuations and blackouts. as a result of this, many people have resorted to the use of diesel generators, with high pollution levels, to satisfy their energy electricity needs. in terms of studies in nigeria, babanyara and saleh [ ] focused on urbanization and fuel wood usage as a source of energy in nigeria between and . fuel price hikes, rural-urban migration and urbanization were identified as the major factors causing fuel wood energy demand in nigeria. it was also confirmed that the country lost an annual average of , hectares of forest to urbanization. it then recommended the harnessing of renewable energy sources as a panacea for reducing the consumption rate of fuel wood in nigeria. jiboye [ ] examined the issues and challenges involved in effective urban governance in nigeria. three major issues of sustainable development and governance, urbanization challenges and the necessity for effectively managing sustainable urbanization were addressed in the study. it was observed that the pervasiveness of urban growth in nigeria has a strong link to globalization, population explosion and industrialization. it therefore called for a participatory and collaborative effort in addressing urbanization crisis. the economic commission for africa (eca) [ ], in its report on urbanization across cities in the world showed that lagos is nigeria’s richest state, producing about $ billion a year in goods and services, making its economy bigger than that of most african countries, including ghana and kenya. in terms of population, it adds , people annually to nigeria’s population. the report concluded that a fastest growing state like lagos without commensurate improvements in social services has pushed lagos to its cliff edge. according to a report on the energy sector in lagos conducted by department for international development (dfid) [ ], lagos was identified as a megacity of over million people and as the economic capital of nigeria. its rapid growth places pressure on resources and the ecosystem to the extent that these services could not support the needs of its citizens. the report also presented a stylized fact about the energy situation in lagos state. the report showed that; ( ) power deficit in lagos equal , - , mw and low utilization of generating capacity; ( ) % of the population has no access to the electricity grid and inadequate transmission capacity; ( ) kwh/yr. average annual consumption; ( ) % of the population relying on diesel generators; ( ) governance challenges federal-state ownership of management of assets; ( ) minimal renewable energy in lagos energy mix and; ( ) fossil fuel subsidies in place. the risk factors facing the lagos energy- electricity sector are highlighted in the report. the report showed that: ( ) million people will be residing in lagos in ; ( ) , engineers will be required for the energy sector over the next years; ( ) $ to $ billion is required to fund investment in energy-electricity generation by depending on technology; ( ) mw new generation capacity will be required for planned mass transit infrastructure and; ( ) , to , mw of new generation capacity will be required in . the potential interventions as shown in the report included: ( ) development of offshore gas; ( ) embedded generation-independent power plant (conventional and renewable); ( ) municipal energy fund to finance rural and urban solar projects; ( ) community biogas project; ( ) offshore wind; ( ) compressed natural gas transportation; ( ) promotion of energy efficient appliances and; ( ) building regulation. from the stylized facts on the lagos energy sector, this study aims to carry out a pilot study of the nexus between urbanization and electricity crisis in lagos, with a view to revealing and understanding the severity of the electricity crisis in the state. the benefit of this pilot study is that it gives a glimpse of what the bigger picture might look like. . methods to arrive an in-depth understanding of the coping strategies of lagos residents to the epileptic power supply, two households with differing social status were interviewed. the first household was chosen from the upper class areas of magodo, lagos. the household include a family of five who live in a duplex while the other household was selected from the slum areas of iwaya, yaba, lagos, which is a family of seven living in a single room apartment in choosing the representative sample, a random sampling method was adopted. the following processes were involved in the final section procedure for the household in magodo area. (i) certain criteria were laid out, which include that the housing must be a duplex, with fence all rounds. also there was a security by the gate side. ( ) the addresses of the duplex were taken. ( ) the chairman of the landlord association was contacted first. ( ) the purpose of the exercise was well communicated to each and every landlord after a formal letter soliciting for their cooperation were served to each of them. ( ) the purpose of the exercise was communicated to each participant before the day. ( ) a piece of paper which carried a “yes” or “no” of addresses of the participants was shuffled and whichever option came up would serve as a representative for the assignment. the same procedure was carried out in iwaya, yaba corridor/axis except that the assumption of being a duplex with fence and security gate was ruled out. the sample, to a very large extent, appeared as a true reflection of the urbanisation and energy crisis: the case of lagos state population of households in nigeria, thus exhibiting the rich and poor dichotomy. in addition, a case study illustrating a typical day in the life of an average lagos state resident was discussed. the locations were chosen purposively. the intention was to select two households with differing social class and status, in order to understand their experiences and coping strategies with the power situation in lagos. magodo is known to be a highbrow area in lagos while iwaya is one of the lower class neighbourhoods in lagos. in the course of this discussion the household from magodo will be referred to as household a (hha) and the household from iwaya will be referred to as household b (hhb). the research methodology employed in this work has been extensively used in the analysis of other related social economic issues (see for example, olurode, [ ], [ ] and tade [ ] among others. in spite of the differing social class and status of the two households focused in this study, the interview revealed that the coping strategies adopted by them were similar but different in terms of intensity and amount. this will be discussed accordingly in the subsequent headings. . results and discussion of findings regularity of power supply in discussing the frequency, duration and stability of power supply in lagos, the two households though in opposite ends of the city, claimed that power supply has been much better of late. they stated that unlike previous experiences when there could be no power supply for two to three days consecutively (and in extreme cases for weeks) electricity supply has become much better because they now enjoy better power supply. upon further probing, the interviewer noted that the ‘better power supply’ the consumers alluded to could be for a period of hours in a day. in their words: “if i had probably had this interview a month ago, i would have said power supply is really bad however, of recent we’ve been enjoying better power supply, we have light at night and during the day, at night from like till the following morning and then maybe they’ll now bring light at around like till , then again till again the next morning…” (idi, hha) “for now the power supply is very stable unlike before, because whenever i get home, i find out that there’s light, there’s light, so most of the things we are able to do it with electricity” (idi, hhb) even though the above account suggests that the power situation might have somewhat improved in lagos, respondents also noted the problems in the quality and distribution of power. “…but about a month ago, we hardly use to have power from disco…and now that there is light, sometimes it is not usually enough to power all the appliances in the house, i don’t understand but its like the power is not distributed evenly. downstairs light is full while upstairs is not at all, while all the sockets downstairs are working, all the lights are working , those upstairs will not and because we can’t put on the generator when there’s light we make use of torches and lamps…” (idi, hha) alternative source of power many residents of lagos are unable to rely solely on the national grid power supply from the discos. this is as a result of previous experiences of unsteady public power supply. many, therefore, resort to using an alternative source for themselves. in the two households interviewed, alternative source of power ranged from the use of industrial generators, to the smaller sized generators (popularly known as ‘i pass my neighbour’) and even to the use of electric charged lamps, solar charged lamps, electric charged torches and kerosene lanterns. in the words of one of the respondents: “we rely on generators at night, and if there is no diesel for the generator, we have charged torchlights that we use, and in the mornings we rarely put on the generator, we make use of the charged lamps and torchlights and at night, we put on the generator from till pm max” (idi, hha) it is also important to mention that although none of the households make use of inverters or solar energy as alternative sources of power, they mentioned having knowledge of neighbours and friends who have such experiences. this point to the fact that inverters and solar energy are also popular means of generating power among the residents in lagos. “i even know people who solely rely on solar energy, they don’t bother with discos anymore” (idi, hha) and although kerosene lanterns are not as common as it was before, it is still commonly used among the lower income families. the respondents from iwaya mentioned that kerosene lanterns are among their major source of light. ‘we have a kerosene lamp in the kitchen, which we use while cooking (idi, hhb) not too surprising, the respondent from magodo felt it was archaic and outdated to use kerosene lamps. in their opinion: “kerosene lamps? no, not at all, that’s like from the th century” (idi, hha) sociology and anthropology ( ): - , dealing with cooking and other domestic tasks owing to the high rate of urbanization in lagos, many residents have abandoned the traditional ways of cooking, carrying out house chores using more modern methods. instead of the use of charcoals and firewood (which are still very common in rural areas) residents of lagos prefer the use electric appliances such as electric cookers, electric irons and so on. this might partly be due to the fact that electrical appliances are better suited to an urban area as they are more space efficient. however, the epileptic power a supply has resulted in residents seeking alternative ways of executing their domestic chores. it is often common experience that residents experience electricity power disruption, in the middle of their cooking which makes looking for alternative sources of power imperative for them. from the interview, it was gathered that the most common alternatives sought after were gas cookers and kerosene stoves for cooking, and for other domestic chores such as ironing. these alternatives have been used as rescues whenever there was power supply disruption. in the words of the respondents: “we iron our clothes beforehand, then for washing, we make use of the dry cleaner. we have washing machine, but we rarely use it because of the power situation, so what we do is we pile up the clothes until there is light, although we kind of make our plans separate from the possibility of power supply from disco, we really don’t rely on disco” (idi, hha) “we don’t store foods as much, because of the unstable power supply, because we might not have light for like two three days, we hardly use the mikano, it’s the small gen we use often and that one cannot carry the freezer, so we hardly buy food in bulk to store. so what we do is buy what we can eat within a short period of time”. (idi, hha) “to generate water, we often have to use the pumping machine to pump water, and for that we need to put on the mikano gen…but if there’s no diesel we either use meruwa (water sellers) or go fetch water from a neighbouring house” (idi, hha) “to grind pepper i have to use local grinder, the stone grinder which makes it very difficult unlike if there’s electricity, i can use the electric blender which makes it easier” (idi, hhb) “to straighten our clothes when there is no light, we fold and put under the pillow or sometimes we can take it to somewhere there is light to iron, we also take chargeable things like phone, torch to charge and pay a token sum to get them charged” (idi, hhb) a day in the life of an average lagos state resident an average resident lives far away from the place of work, thus he has to wake up at . a.m. or thereabout. his/her travels time to work would be some two hours to his/her place of residence. however, while he/she is planning to get his/her clothes ready, public power supply goes off. upon waking up, he rushes his prayers, quickly gets hold of the pressing iron to complete the exercise. his plan to leave the house by . a.m. has to be given up. public power went off before he could complete the ironing. attempts to put his power generator (popularly called i pass my neighbour) is frustrated. there is not enough fuel in the generator and the plug looks bad. having given up on ironing, he rushes out to the bus stop to meet a long queue. of course, he makes it late to work but much before his boss could arrive. but the line has been drawn. upon getting inside his office, he quickly charges his phone which had run out of power. he also has enough time to boil water to make tea as he could not make breakfast before leaving the house. a day or two before he had thrown away all the fruits and food in his freezer. they had gone bad because of epileptic power supply. but our average resident is having a sigh of relief as additional hours are being added to public power supply. he now spends less diesel and petrol. but still, he is unable to plan as constant public power supply cannot be guaranteed. for the most part, he has to contend with ‘never expect power always’ – a sad commentary on the acronym of the old agency saddled with public power supply – nepa. at his backyard, the lagos resident would have some disused generators – a junk backyard of a sort. not a small percentage of his monthly income is spent on diesel or petrol purchase. he has to sleep most night without public power supply. whenever the weather is unfriendly, he is forced to sleep in the open, not minding severe mosquito bite, which makes many vulnerable to malaria – a killer disease. . conclusions an assessment of the reliability of power supply in lagos state shows that all the respondents agreed to the relative stability of electricity, which has made them to enjoy their electricity-powered appliances. this is a pointer to the fact that time dimension is an important factor when assessing the reliability of electricity supply in nigeria. in fact, electricity is more stable during the rainy season in nigeria. during this period, hydro power stations generate optimally, with attendant positive effects on the quantum of electricity supply in nigeria. in other words, the various efforts of the lagos state government to boost power supply in lagos has been complemented by the climatic factor. the implication of this is that there is a need to ensure an appropriate energy mix in the generation urbanisation and energy crisis: the case of lagos state of electricity in nigeria. this argument has been extensively discussed elsewhere; see for example isola [ ] and [ ]. there is no doubt that the quantum of electricity generated in nigeria is still very low. a comparative analysis of nigeria with her supposed counterparts the united energy information agency data is able to show that in the install generating capacity in brazil was , megawatts; similarly, south africa generated , mw; while egypt generated , mw. nigeria’s installed capacity is , mw, but highest daily output in october, was about , mw. this is considered too dismal for an economy which experts say needs a minimum of , mw. perhaps it has become necessary to take a cue from other countries such as peru, argentina and chile where the privatization of power infrastructure has been effective. in argentina for instance, power generation post-privatization rose from about , mw in to about , mw in . the reverse is the case in nigeria, which explains the high electricity supply gap in lagos state. this also explains the need to revisit the privatization process of the discos and the gencos. this will be to ensure and appreciate the beauty of transferring of government companies to the private sector as it was done to the telecommunication industry. finally, the responses from the interviewees indicate that both high and lower neighbourhoods in lagos experience unstable epileptic power supply and that resident have learnt to cope and adapt with the power situation using diverse strategies of coping. the coping mechanisms, however, are based on financial capabilities. from the interviews, it was apparent that both high income and low income families tend towards the use of generators. however, they also make use of lamps and solar energy in few cases. both classes of families also use gas stoves as an alternative to electric stoves for cooking and occasionally they use kerosene stoves. planning ahead was also a recurring feature among the households and families, which indicated how they prepared for the possibility of power outage. planning ahead is thus part of the respondents’ coping mechanisms. the way out of the problem is to fully implement the power sector reform. this is capable of providing an efficient supply of power in the urban cities and rural areas. more importantly, this can be achieved through the rural electrification initiatives. references [ ] arnulf, g., & jayant s. 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( ). urbanization, energy use and greenhouse effects in economic development: results from a cross-national study of developing countries. global environmental change, ( ), - . [ ] salau, t. ( ) urbanisation and the state of infrastructure in the developing world” in kadiri w. a. (ed.) our cities, our future: dialogue on urban planning challenges and management. abeokuta: gbenga gbesan associates. [ ] shahbaz, m., & lean, h. h. ( ). does financial development increase energy consumption? the role of industrialization and urbanization in tunisia. energy policy, , - . [ ] shen, l., cheng, s., gunson, a. j., & wan, h. ( ). urbanization, sustainability and the utilization of energy and mineral resources in china. cities, ( ), - . [ ] simon b, & innocent s.k.a. ( ). the nexus between urbanization and energy in ghana: a literature review. isser, university of ghana. 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[ ] world bank ( ). access to electricity (% of population). world development indicators http://data.worldbank.org/i ndicator/eg.elc.accs.zs [ ] world economic outlook ( ). energy access database. http://www.worldenergyoutlook.org/resources/energydevel opment/energyaccessdatabase/ [ ] zhou, w., zhu, b., chen, d., griffy-brown, c., ma, y., & fei, w. ( ). energy consumption patterns in the process of china’s urbanization. population and environment, ( - ), - https://www.washingtonpost.com/graphics/world/world-without-power/ https://www.washingtonpost.com/graphics/world/world-without-power/ http://data.worldbank.org/indicator/eg.elc.accs.zs http://data.worldbank.org/indicator/eg.elc.accs.zs http://data.worldbank.org/indicator/eg.elc.accs.zs http://www.worldenergyoutlook.org/resources/energydevelopment/energyaccessdatabase/ http://www.worldenergyoutlook.org/resources/energydevelopment/energyaccessdatabase/ 	 . introduction 	 . literature review 	 . methods 	 . results and discussion of findings 	 . conclusions 	references february book review kissinger and brazil thiago galvão gehre i n kissinger and brazil matias spektor addresses an important episode in brazil and the united states’ relations. he tells how henry kissinger became a focal point for brazilian diplomacy in its quest for great power status. spektor, one of the new generation of brazilian historians of international relations, heads the center for the study of international relations of the getulio vargas foundation and is an expert on archival research. the book’s main thesis is that brazil has worked its way into the international system, seeking recognition from other countries for its own national goals. with the u.s., brazil sought to avoid either submission or rivalr y, establish itself as one of the building blocks of global order, and not follow without serious thought the precepts of the northern giant. the book describes the evolution of the rapprochement during the s between u.s. and brazil under the skillful diplomatic command of henry kissinger and antonio francisco azeredo da silveira, the brazilian foreign minister. spektor covers kissinger’s experiment in bringing brazil to the center of u.s. foreign policy; the efforts of matias spektor, kissinger e o brasil (rio de janeiro: jorge zahar ed, ). p. thiago galvão gehre is professor of the history of international relations in the department of international relations at the federal university of roraima – ufrr. he holds a ph.d. in international relations from the university of brasilia – unb. thiago.gehre@gmail.com. february book review kissinger and da silveira to build up a partnership; the estrangement with president jimmy carter; and the dismantling of the partnership by ronald reagan in the s. kissinger’s experiment was an effort to modify the static landscape of brazil-us relations. a controlling concept was “delegation” — the transfer of responsibilities to major regional players. spek tor explains that, in seeking to make u. s. foreign p olic y conceptually and philosophically more consistent, kissinger opened the way for countries like brazil, china, indonesia, and south africa to carry more weight in their relations with the u.s. the aim was to rid the u.s. of the stigma of imperialism and create a sense of partnership to legitimize u.s. actions around the globe. the partnership started with the visit of brazilian president ernesto geisel to the u.s. capital on december , . preparation for the trip was turbulent. there was unresolved tension between activism and withdrawal in brazil’s foreign policy because of a rift between the president and the foreign ministry. there was also a divergence between how brazil and the u.s. conceived of the partnership. spektor points out that “from the american point of view, approaching brazil would be consciously elusive” (p. ). in any event, after the first step, both countries benefitted from improved relations based more on the personal relations of policy makers than on any formal institutional framework. president geisel and da silveira developed a new strategic model that advocated searching for new partnerships and revising relations with argentina and the u.s. da silveira’s foreign affairs management is regarded as highly activist; during his term “the international ambitions of brazil grew more than [in] any previous period” (p. ). da silveira searched for “small spaces of ‘autonomy’ on the margins of the liberal west” to support brazil’s national development project. he tried to conceptually advance foreign policy to address brazil’s economic growth and growing international influence. spektor points out that the problem was not in the international system: “at home brazil’s strategic concepts had become archaic” (p. ). the book celebrates the compatibility between da silveira and kissinger and their efforts to build a more constructive engagement between their countries, a “special non-aligned relationship.” the world in was witnessing the rise of peripheral powers and the crisis of traditional powers that according to spektor would move “the tectonic plates of international politics” ( p. ) . the bilateral agenda covered trade issues, the global energy crisis, nuclear proliferation, activity in post- independence africa, and the cuban presence in south america. brazil struggled against distrust, anxiety, and a lack of willingness in the u.s. to recognize it as a great power. but the u.s. kept the dialogue open even as it contained brazil’s ambitions. the intensit y of the brazil-us par tnership contrasts with the brevity of the dialogue between kissinger and da silveira. the partnership moved ahead amid the s energy crisis, president geisel’s decision to support the arabs against israel, and the involvement of brazil in angola’s independence movement. these three events tested the resilience of the american relationship with brazil at a point where the partnership could well be formalized. consequently, brazil did not choose sides in the oil issue, assuming a pragmatic detachment; with regard to israel, brazil first chose the book’s main thesis is that brazil has worked its way into the international system, seeking recognition from other countries for its own national goals. february book review to abstain and then condemned the vote on the un resolution that declared zionism to be a form of racism. and it flinched when the cultural ties that justified a brazilian presence in angola clashed with the u.s. grand strategy to combat communism. da silveira took advantage of small crises to catalyze a more consistent foreign policy. spektor tells of kissinger’s second trip to brazil and its implications for brazil-u.s. relations. the brazilian challenge was to bring about a flexible partnership that would promote understanding between the two countries but that would not tie brazil to joint commitments and would guarantee president geisel control over the process of political opening in brazil. the memorandum of understanding between the two countries was ingeniously “simple and vague,” allowing “maximum freedom of maneuver for each side” (p. ). the resilience of the partnership would later be tested by a diplomatic imbroglio over the independence of east timor, an alleged brazilian plan to invade guyana, and the tense relationship between the u.s. and chile. in all these situations, the memorandum guaranteed open channels to treat them in the light of common interests. progress was stymied by brazilian fears of generating and later frustrating u.s. expectations, according to spektor (p. ); and the election of jimmy carter brought about an upheaval in u.s. and brazil relations. the discomfort caused by systematic human rights abuses and the fear generated by the nuclear agreement between brazil and germany stirred up discussion. the memorandum was the only defense available, a shield against carter administration revisionism. when ronald reagan came to power, kissinger lef t the scene and da silveira moved to the brazilian embassy in washington. the brazilian strategy then became a conscious distancing from washington in view of the impossibility of dialogue and the neoliberal advance. even so, spek tor concludes, brazil catapulted its position in the international hierarchy from an anti-communist agent to an international power, ensuring the country’s autonomy in the context of overwhelming asymmetry with washington. matias spektor writes in a clear and objective way that makes reading enjoyable even for those who are not specialists in international relations. he uses international relations theory parsimoniously — almost imperceptibly for the general reader. he has uncovered striking events deep within the records and has had access to unpublished national and foreign sources, contributing notably to research on the history of brazil’s international relations. however, spektor seems to give too much value to statesmen’s capacity to promote change in the world. he is of the view that “international politics is not predestined. with ideas and leaders willing to take risks, existing views may be adjusted or replaced with better ones”(p. ). this raises questions: did kissinger make brazil his laboratory for experiments with regional powers? or was it da silveira who discovered in kissinger the cure for brazil’s “invisible power” syndrome? in either case, the situation of brazil and south america at the time must have certainly weighed on the decisions of policy makers. kissinger opened the way for countries like brazil, china, indonesia, and south africa to carry more weight in their relations with the u.s.. progress [in brazil-u.s. relations] was stymied by brazilian fears of generating and later frustrating u.s. expectations. february book review effect of exhaust gases temperature on the performance of a hybrid heat recovery system hal id: hal- https://hal.univ-angers.fr/hal- submitted on apr hal is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. the documents may come from teaching and research institutions in france or abroad, or from public or private research centers. l’archive ouverte pluridisciplinaire hal, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. effect of exhaust gases temperature on the performance of a hybrid heat recovery system hassan jaber, mahmoud khaled, thierry lemenand, jallal faraj, hasan bazzi, mohamad ramadan to cite this version: hassan jaber, mahmoud khaled, thierry lemenand, jallal faraj, hasan bazzi, et al.. effect of exhaust gases temperature on the performance of a hybrid heat recovery system. tmrees international conference on technologies and materials for renewable energy, environment and sustainability, apr , beyrouth, lebanon. pp. - , � . /j.egypro. . . �. �hal- � https://hal.univ-angers.fr/hal- https://hal.archives-ouvertes.fr sciencedirect available online at www.sciencedirect.comavailable online at www.sciencedirect.com sciencedirect energy procedia ( ) – www.elsevier.com/locate/procedia - © the authors. published by elsevier ltd. peer-review under responsibility of the scientific committee of the th international symposium on district heating and cooling. the th international symposium on district heating and cooling assessing the feasibility of using the heat demand-outdoor temperature function for a long-term district heat demand forecast i. andrića,b,c*, a. pinaa, p. ferrãoa, j. fournierb., b. lacarrièrec, o. le correc ain+ center for innovation, technology and policy research - instituto superior técnico, av. rovisco pais , - lisbon, portugal bveolia recherche & innovation, avenue dreyfous daniel, limay, france cdépartement systèmes Énergétiques et environnement - imt atlantique, rue alfred kastler, nantes, france abstract district heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. these systems require high investments which are returned through the heat sales. due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. the main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand forecast. the district of alvalade, located in lisbon (portugal), was used as a case study. the district is consisted of buildings that vary in both construction period and typology. three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). to estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. the results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than % for all weather scenarios considered). however, after introducing renovation scenarios, the error value increased up to . % (depending on the weather and renovation scenarios combination considered). the value of slope coefficient increased on average within the range of . % up to % per decade, that corresponds to the decrease in the number of heating hours of - h during the heating season (depending on the combination of weather and renovation scenarios considered). on the other hand, function intercept increased for . - . % per decade (depending on the coupled scenarios). the values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. © the authors. published by elsevier ltd. peer-review under responsibility of the scientific committee of the th international symposium on district heating and cooling. keywords: heat demand; forecast; climate change energy procedia ( ) – - © the authors. published by elsevier ltd. peer-review under responsibility of the euro-mediterranean institute for sustainable development (eumisd). . /j.egypro. . . . /j.egypro. . . - available online at www.sciencedirect.com sciencedirect	 energy procedia ( ) – www.elsevier.com/locate/procedia - © the authors. published by elsevier ltd. peer-review under responsibility of the euro-mediterranean institute for sustainable development (eumisd). international conference on technologies and materials for renewable energy, environment and sustainability, tmrees , - april , beirut lebanon effect of exhaust gases temperature on the performance of a hybrid heat recovery system hassan jaber a,c, mahmoud khaled a,b,*, thierry lemenand c , jallal faraj a, hasan bazzi a and mohamad ramadana,d a school of engineering, lebanese international university liu, po box beirut, lebanon. b univ paris diderot, sorbonne paris cité, interdisciplinary energy research institute (pieri), paris, france c laris ea , university of angers  istia, angers, france dassociate member at fclab, cnrs, univ. bourgogne franche-comte , belfort cedex, france. abstract the reuse or reduction of wasted heat supplies an excellent opportunity for cost saving in industrial and residential application. this paper deals with a hybrid heat recovery system that reuses the thermal energy captured by exhaust gases to produce domestic hot water and generate electric power using thermoelectric generators (teg). the heat recovery process is mainly affected by the temperature of exhaust gases. the effect of gases temperature on the performance of the system  water temperature and power generated  is studied including different residential applications. it shows that as the exhaust gases temperature increase the heat rate, water temperature, and power generated increases. © the authors. published by elsevier ltd. peer-review under responsibility of the euro-mediterranean institute for sustainable development (eumisd). keywords: heat recovery; thermoelectric generators; cogeneration; thermal modeling; domestic hot water; * corresponding author. tel.; e-mail address: mahmoud.khaled@liu.edu.lb . introduction due to the rapid increase in demand and consumption of energy, scientists are forced to find solutions of what is called “energy crisis”. fossil fuel remains still the main energy resource that feeds most industrial and residential applications. renewable energy and energy management are certainly the most effective solutions of energy crisis available online at www.sciencedirect.com sciencedirect	 energy procedia ( ) – www.elsevier.com/locate/procedia - © the authors. published by elsevier ltd. peer-review under responsibility of the euro-mediterranean institute for sustainable development (eumisd). international conference on technologies and materials for renewable energy, environment and sustainability, tmrees , - april , beirut lebanon effect of exhaust gases temperature on the performance of a hybrid heat recovery system hassan jaber a,c, mahmoud khaled a,b,*, thierry lemenand c , jallal faraj a, hasan bazzi a and mohamad ramadana,d a school of engineering, lebanese international university liu, po box beirut, lebanon. b univ paris diderot, sorbonne paris cité, interdisciplinary energy research institute (pieri), paris, france c laris ea , university of angers  istia, angers, france dassociate member at fclab, cnrs, univ. bourgogne franche-comte , belfort cedex, france. abstract the reuse or reduction of wasted heat supplies an excellent opportunity for cost saving in industrial and residential application. this paper deals with a hybrid heat recovery system that reuses the thermal energy captured by exhaust gases to produce domestic hot water and generate electric power using thermoelectric generators (teg). the heat recovery process is mainly affected by the temperature of exhaust gases. the effect of gases temperature on the performance of the system  water temperature and power generated  is studied including different residential applications. it shows that as the exhaust gases temperature increase the heat rate, water temperature, and power generated increases. © the authors. published by elsevier ltd. peer-review under responsibility of the euro-mediterranean institute for sustainable development (eumisd). keywords: heat recovery; thermoelectric generators; cogeneration; thermal modeling; domestic hot water; * corresponding author. tel.; e-mail address: mahmoud.khaled@liu.edu.lb . introduction due to the rapid increase in demand and consumption of energy, scientists are forced to find solutions of what is called “energy crisis”. fossil fuel remains still the main energy resource that feeds most industrial and residential applications. renewable energy and energy management are certainly the most effective solutions of energy crisis © the authors. published by elsevier ltd. peer-review under responsibility of the euro-mediterranean institute for sustainable development (eumisd). http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf hassan jaber et al. / energy procedia ( ) – author name / energy procedia ( ) – [ ]. renewable energy which is an alternative source of energy is mainly generated from solar, wind, biomass, geothermal, and hydropower [ - ]. energy recovery consists in the reuse of energy dumped to the environment without taking advantage of it [ - ]. because of the high dependence of fossil fuel which is burned to generate thermal energy, high amount of exhaust gases are generated which could be the highest energy loss in the system. recovering heat from exhaust gases can be done directly or indirectly by a mean of heat exchanger or any energy transformation process. jaber et al. [ ] did a short review on heat recovery, classifying it into different configurations. the authors classified exhaust gas heat recovery systems within three classifications that are exhaust gas temperature, utilized equipment and proposed a new classification according to recovery purposes. this paper deals with heat recovery from exhaust gases. a hybrid heat recovery system proposed is utilized to recover exhaust gases to produce simultaneously domestic hot water and generate electricity using thermoelectric generators (teg). the concept of study is discussed in section . section presents the thermal modeling of the system, and section studies the effect of changing exhaust gases temperature on the performance of the system. finally a conclusion about the whole study is carried. nomenclature a area [m ] h convection heat transfer coefficient [w/m .k] hhrs hybrid heat recovery system q heat transfer rate [w] l length of the tank [m] n number of items p power produced [w] r radius [m] ta temperature [°c] k thermal conductivity [w/m.k] r thermal resistance [k/w] e thickness of the teg [m] . heat recovery concept the relatively high amount of thermal energy lost through exhaust gases forced scientists to investigate how to get benefit of this energy. variety of studies were made in the field of heat recovery including single or hybrid heat recovery systems. this paper proposes a hybrid heat recovery system in which hot water is produced and electric power is generated. the system is composed of water tank with a pipe passing through it. at the inner wall of the pipe a thermoelectric generators layer is attached allowing a direct contact of exhaust gases with tegs. part of the thermal energy hold by exhaust gases transfer through the tegs layer in which this teg layer dissipate heat to the water at the tank. the tegs layer is sandwiched between the exhaust gases (heat source) and the inner wall of the tube (heat sink) [ ]. as the tegs are subjected to a temperature difference an electric power is generated. figure shows a schematic of the proposed hybrid heat recovery system. it shows a pipe crosses the tank in which exhaust gases passes through the pipe with a direct contact with the teg layer (red layer). teg in its turn convert part of the absorbed thermal energy to electrical energy and dissipate the other part to water. the quantity and quality of exhaust gases plays a crucial role in the recovery process. the effect of exhaust gases temperature on water temperature and power generated is examined in this paper. to proceed, a thermal modelling of the system will be carried in order to obtain the behaviour of the hybrid heat recovery system while changing the temperature of author name / energy procedia ( ) – exhaust gases fig. . hybrid heat recovery system. . thermal modeling in order to estimate the water temperature and the power generated by water a thermal modelling of the system is carried out. some assumptions are used to simplify the calculation: the study is done at steady state, one dimensional heat flow and constant gases temperature along the tank length. figure shows the steps required to obtain the water temperature and the power generated. fig. . thermal modelling steps. as shown in figure , in order to obtain the heat flow rate the total resistance of the hhrs should be calculated. knowing the gases temperature and ambient air temperature, the temperature at each layer could be calculated in which the heat flow rate (q) is constant over the system. to obtain the total power, the power generated by one teg should be estimated and multiplied by the number of tegs available. the power generated by one teg is estimated by a direct relation with the temperature difference at the teg. figure shows the thermal resistance diagram of the system. the thermal energy captured by exhaust gases hassan jaber et al. / energy procedia ( ) – author name / energy procedia ( ) – [ ]. renewable energy which is an alternative source of energy is mainly generated from solar, wind, biomass, geothermal, and hydropower [ - ]. energy recovery consists in the reuse of energy dumped to the environment without taking advantage of it [ - ]. because of the high dependence of fossil fuel which is burned to generate thermal energy, high amount of exhaust gases are generated which could be the highest energy loss in the system. recovering heat from exhaust gases can be done directly or indirectly by a mean of heat exchanger or any energy transformation process. jaber et al. [ ] did a short review on heat recovery, classifying it into different configurations. the authors classified exhaust gas heat recovery systems within three classifications that are exhaust gas temperature, utilized equipment and proposed a new classification according to recovery purposes. this paper deals with heat recovery from exhaust gases. a hybrid heat recovery system proposed is utilized to recover exhaust gases to produce simultaneously domestic hot water and generate electricity using thermoelectric generators (teg). the concept of study is discussed in section . section presents the thermal modeling of the system, and section studies the effect of changing exhaust gases temperature on the performance of the system. finally a conclusion about the whole study is carried. nomenclature a area [m ] h convection heat transfer coefficient [w/m .k] hhrs hybrid heat recovery system q heat transfer rate [w] l length of the tank [m] n number of items p power produced [w] r radius [m] ta temperature [°c] k thermal conductivity [w/m.k] r thermal resistance [k/w] e thickness of the teg [m] . heat recovery concept the relatively high amount of thermal energy lost through exhaust gases forced scientists to investigate how to get benefit of this energy. variety of studies were made in the field of heat recovery including single or hybrid heat recovery systems. this paper proposes a hybrid heat recovery system in which hot water is produced and electric power is generated. the system is composed of water tank with a pipe passing through it. at the inner wall of the pipe a thermoelectric generators layer is attached allowing a direct contact of exhaust gases with tegs. part of the thermal energy hold by exhaust gases transfer through the tegs layer in which this teg layer dissipate heat to the water at the tank. the tegs layer is sandwiched between the exhaust gases (heat source) and the inner wall of the tube (heat sink) [ ]. as the tegs are subjected to a temperature difference an electric power is generated. figure shows a schematic of the proposed hybrid heat recovery system. it shows a pipe crosses the tank in which exhaust gases passes through the pipe with a direct contact with the teg layer (red layer). teg in its turn convert part of the absorbed thermal energy to electrical energy and dissipate the other part to water. the quantity and quality of exhaust gases plays a crucial role in the recovery process. the effect of exhaust gases temperature on water temperature and power generated is examined in this paper. to proceed, a thermal modelling of the system will be carried in order to obtain the behaviour of the hybrid heat recovery system while changing the temperature of author name / energy procedia ( ) – exhaust gases fig. . hybrid heat recovery system. . thermal modeling in order to estimate the water temperature and the power generated by water a thermal modelling of the system is carried out. some assumptions are used to simplify the calculation: the study is done at steady state, one dimensional heat flow and constant gases temperature along the tank length. figure shows the steps required to obtain the water temperature and the power generated. fig. . thermal modelling steps. as shown in figure , in order to obtain the heat flow rate the total resistance of the hhrs should be calculated. knowing the gases temperature and ambient air temperature, the temperature at each layer could be calculated in which the heat flow rate (q) is constant over the system. to obtain the total power, the power generated by one teg should be estimated and multiplied by the number of tegs available. the power generated by one teg is estimated by a direct relation with the temperature difference at the teg. figure shows the thermal resistance diagram of the system. the thermal energy captured by exhaust gases hassan jaber et al. / energy procedia ( ) – author name / energy procedia ( ) – undergoes convection heat transfer with the surface of the teg (rg). at the teg the energy transfer by conduction through the layers of teg and pipe to water (rteg , rp). due to the change in density of water, water will undergoes natural convection with the walls of the pipe and the tank (r conv,w-p , r conv,w-w). at the tanks’ wall energy transfer through the wall by conduction (r wall) and with the air through convection heat transfer (r air). fig. . thermal resistance of the system. where tg,i, th, tc, tp,o, tw, twall,i, twall,o and ta are the temperature of exhaust gases, hot, cold, outer pipe wall, water, inner tank wall, outer tank wall, and ambient air temperature respectively. and rg, rteg, rp, rconv,w-p, rconv,w-w, rwall, and rair, are the thermal resistance of internal convection of gases in pipe, conduction in thermoelectric generator, conduction in the pipe wall, convection between water and pipe , convection between water and cylindrical tank wall, conduction in the cylindrical tank wall and convection of tank with air respectively. the thermal resistances are calculated using the following equations [ ]:   lerhr i,tgg      ( ) lk er r ln r teg i,t i,t teg            ( ) lk r r ln r t i,t o,t p           ( )  lrhr o,twpw,conv     ( )  lrhr i,wwww,conv     ( ) lk r r ln r w i,w o,w wall           ( )  lrhr o,waair     ( ) where hg, hw and ha are the convection heat coefficient of exhaust gases, water and air respectively. kteg, kt and kw are the conduction coefficient of the teg, tube wall and tank wall respectively. and rt,i, rt,o, rw,i, rw,o and l are the inner, outer radius of the tube and inner, outer radius of the water tank, and length of the tank respectively. e is the thickness of the thermoelectric generator. knowing that heat flow rate is constant over the system then the temperature at each point can be estimated by the author name / energy procedia ( ) – following equation: )n()n()n( r.qtt     ( ) where q is the heat flow rate in “w” and n is an increment of the layers of the hhrs starting from exhaust gases to air. by calculating the hot and cold temperature at the teg surface the power produced by one teg is calculated as follows: tt p p ref teg            ( ) where p teg is the output power of one teg, is the temperature difference between the hot and cold sides of teg, and is given by the manufacturer of the teg. then the total power produced by tegs ptotal is estimated by equation below knowing that nteg is the number of tegs available on the system: tegtegtotal pnp     ( ) . results one of the main parameters that affects the performance of heat recovery process is the gases temperature. variety of applications that can be utilized as exhaust gases source of the system can be found. for a residential level: generators, chimney, boilers and furnaces are the main applications found. table shows the dimensions of the system used and the main parameters required for the thermal modeling. in order to simplify the study the heat convection coefficient of the exhaust gases is set as constant. it should be noted that a specific type of teg is utilized and its main parameters are listed in table [ ]. table . heat recovery system main parameters. parameter value unit rt,,i . m rt,o . m l m rw,i . m rw,o . m hw w/m k ha w/m k hg w/m k kt w/mk kwall w/mk kteg . w/mk nteg piece ta °c e . m p/∆t . w/k ateg . m using the table and equations above the effect of changing exhaust gases temperature on the heat rate, temperature variation, temperature difference at the teg and power produced by tegs is studied. figure shows the variation of heat flow by varying the exhaust gases temperature. hassan jaber et al. / energy procedia ( ) – author name / energy procedia ( ) – undergoes convection heat transfer with the surface of the teg (rg). at the teg the energy transfer by conduction through the layers of teg and pipe to water (rteg , rp). due to the change in density of water, water will undergoes natural convection with the walls of the pipe and the tank (r conv,w-p , r conv,w-w). at the tanks’ wall energy transfer through the wall by conduction (r wall) and with the air through convection heat transfer (r air). fig. . thermal resistance of the system. where tg,i, th, tc, tp,o, tw, twall,i, twall,o and ta are the temperature of exhaust gases, hot, cold, outer pipe wall, water, inner tank wall, outer tank wall, and ambient air temperature respectively. and rg, rteg, rp, rconv,w-p, rconv,w-w, rwall, and rair, are the thermal resistance of internal convection of gases in pipe, conduction in thermoelectric generator, conduction in the pipe wall, convection between water and pipe , convection between water and cylindrical tank wall, conduction in the cylindrical tank wall and convection of tank with air respectively. the thermal resistances are calculated using the following equations [ ]:   lerhr i,tgg      ( ) lk er r ln r teg i,t i,t teg            ( ) lk r r ln r t i,t o,t p           ( )  lrhr o,twpw,conv     ( )  lrhr i,wwww,conv     ( ) lk r r ln r w i,w o,w wall           ( )  lrhr o,waair     ( ) where hg, hw and ha are the convection heat coefficient of exhaust gases, water and air respectively. kteg, kt and kw are the conduction coefficient of the teg, tube wall and tank wall respectively. and rt,i, rt,o, rw,i, rw,o and l are the inner, outer radius of the tube and inner, outer radius of the water tank, and length of the tank respectively. e is the thickness of the thermoelectric generator. knowing that heat flow rate is constant over the system then the temperature at each point can be estimated by the author name / energy procedia ( ) – following equation: )n()n()n( r.qtt     ( ) where q is the heat flow rate in “w” and n is an increment of the layers of the hhrs starting from exhaust gases to air. by calculating the hot and cold temperature at the teg surface the power produced by one teg is calculated as follows: tt p p ref teg            ( ) where p teg is the output power of one teg, is the temperature difference between the hot and cold sides of teg, and is given by the manufacturer of the teg. then the total power produced by tegs ptotal is estimated by equation below knowing that nteg is the number of tegs available on the system: tegtegtotal pnp     ( ) . results one of the main parameters that affects the performance of heat recovery process is the gases temperature. variety of applications that can be utilized as exhaust gases source of the system can be found. for a residential level: generators, chimney, boilers and furnaces are the main applications found. table shows the dimensions of the system used and the main parameters required for the thermal modeling. in order to simplify the study the heat convection coefficient of the exhaust gases is set as constant. it should be noted that a specific type of teg is utilized and its main parameters are listed in table [ ]. table . heat recovery system main parameters. parameter value unit rt,,i . m rt,o . m l m rw,i . m rw,o . m hw w/m k ha w/m k hg w/m k kt w/mk kwall w/mk kteg . w/mk nteg piece ta °c e . m p/∆t . w/k ateg . m using the table and equations above the effect of changing exhaust gases temperature on the heat rate, temperature variation, temperature difference at the teg and power produced by tegs is studied. figure shows the variation of heat flow by varying the exhaust gases temperature. hassan jaber et al. / energy procedia ( ) – author name / energy procedia ( ) – figure . effect of exhaust gases temperature on heat rate. the heat transfer rate increases linearly with the increase in exhaust gases temperature. this is directly reflected by the following equation: total a g total g r t t r tq  )(   ( ) figure shows the temperature distribution on different layers on the system. figure . variation in temperature distribution of the system. h ea t f lo w (w ) gases temperature (°c) te m pe ra tu re (° c ) gases temperature (°c) th tc t po tw twall,i twall, o author name / energy procedia ( ) – the temperature at any layer in the system increased linearly with the increase in exhaust gases temperature. it should be noted that cold side temperature of the teg tc and the outer tube wall have a relatively equal temperature which is due to the small tube thickness and high thermal conductivity which reflect the invisibility of tc on the graph.. also twall,i and t wall,o are approximately equal due to the low thickness of the tanks’ wall. figure shows the power generated by one teg and the corresponding temperature difference at the two sides of the teg. figure . temperature difference and power generated by one teg. it shows that the power generated by one teg is continuously increasing with the increase in exhaust gases temperature. for a °c exhaust gases, . w of electricity is being produced at a . °c temperature difference between the hot and cold sides of the teg. while for °c, . w electric power is produced at a °c temperature difference. figure shows the effect of changing the exhaust gases temperature on the total power produced by the tegs layer. figure . total power produced by tegs. . . . . . . . . te m pe ra tu re d iff er en ce (° c ) po w er p ro du ce d by t e g (w ) gases temperature (°c) p teg ∆t to ta l p ow er (w ) gases temperature (°c) hassan jaber et al. / energy procedia ( ) – author name / energy procedia ( ) – figure . effect of exhaust gases temperature on heat rate. the heat transfer rate increases linearly with the increase in exhaust gases temperature. this is directly reflected by the following equation: total a g total g r t t r tq  )(   ( ) figure shows the temperature distribution on different layers on the system. figure . variation in temperature distribution of the system. h ea t f lo w (w ) gases temperature (°c) te m pe ra tu re (° c ) gases temperature (°c) th tc t po tw twall,i twall, o author name / energy procedia ( ) – the temperature at any layer in the system increased linearly with the increase in exhaust gases temperature. it should be noted that cold side temperature of the teg tc and the outer tube wall have a relatively equal temperature which is due to the small tube thickness and high thermal conductivity which reflect the invisibility of tc on the graph.. also twall,i and t wall,o are approximately equal due to the low thickness of the tanks’ wall. figure shows the power generated by one teg and the corresponding temperature difference at the two sides of the teg. figure . temperature difference and power generated by one teg. it shows that the power generated by one teg is continuously increasing with the increase in exhaust gases temperature. for a °c exhaust gases, . w of electricity is being produced at a . °c temperature difference between the hot and cold sides of the teg. while for °c, . w electric power is produced at a °c temperature difference. figure shows the effect of changing the exhaust gases temperature on the total power produced by the tegs layer. figure . total power produced by tegs. . . . . . . . . te m pe ra tu re d iff er en ce (° c ) po w er p ro du ce d by t e g (w ) gases temperature (°c) p teg ∆t to ta l p ow er (w ) gases temperature (°c) hassan jaber et al. / energy procedia ( ) – author name / energy procedia ( ) – when the temperature of exhaust gases was °c the total power is total power produced is w, when the exhaust gases temperature is doubled ( °c) the total power is w. this indicates that the relation between power and exhaust gases is not linear and when the temperature of gases doubled the power increased times from what it was. . conclusion heat recovery offers an excellent opportunity for cost and energy saving in industrial and residential applications. the heat recovery process is mainly affected by the quality and quantity of thermal energy lost. in other words, heat recovery from exhaust gases is affected by the exhaust gases temperature and flow rate. the effect of exhaust gases on a proposed hybrid heat recovery system is studied. a domestic thermoelectric cogeneration heat recovery system is utilized in this study. the results shows that by increasing the gases temperature, the heat rate and temperatures at each layer increase linearly. the power generated by teg progressively increases with the increase on exhaust gases temperature. also it was shown that for the utilized configuration of hhrs, when doubling the gases temperature the power produced increases about times more. references [ ] williams a., kennedy s., philipp f., whiteman g. systems thinking: a review of sustainability management research. journal of cleaner production, ; : - . 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[ ] tecteg, manufacturer of thermoelectric modules, . available from: www.tecteg.com original article summary objective: the authors show the clinical evaluation and follow-up results in pa- tients diagnosed with a failed back surgery pain syndrome. methods: descriptive and prospective study conducted over a one-year period. in this study, patients with a failed back surgery pain syndrome were assessed in our facility. the age ranged from to years (mean, .  ±  . years). the pain was assessed through a visual analog scale (vas). results: postoperative pain was more severe (mean vas score . ) than preoperative pain ( . ). myofascial pain syndromes (mps) were diagnosed in . % of patients; neuropathic abnormalities associated or not with mps were found in . %. drug therapy associated with physical medicine treatment provided ≥  % pain im- provement in . % of cases; trigger point injection in . %, and epidural infusion of morphine with lidocaína in . % of refractory cases. conclusion: in patients with a post-laminectomy syndrome, postoperative pain was more severe than preoperative pain from a herniated disk. a miofascial component was found in most patients. keywords: low back pain; intervertebral disk displacement; post-laminectomy syn- drome. study conducted at the pain center, department of neurology, clinical hospital of usp school of medicine, são paulo, sp, brazil submitted on: / / approved on: / / correspondence to: wellingson silva paiva divisão de neurocirurgia funcional e centro de dor hospital das clínicas da faculdade de medicina da usp r. dr. eneas aguiar, º andar – cerqueira césar são paulo – sp cep: - wellingsonpaiva@yahoo.com.br conflicts of interest: none. failed back surgery pain syndrome: therapeutic approach descriptive study in patients manoel jacobsen teixeira , lin tchia yeng , oliver garcia garcia , erich talamoni fonoff , wellingson silva paiva , joaci o araujo lecturer; chair professor in neurosurgery, school of medicine, universidade de são paulo (usp), são paulo, sp, brazil ph.d. in science; pain center coordinator, division of physical medicine, clinical hospital of the school of medicine, usp, são paulo, sp, brazil m.d.; residence in neurosurgery; medical trainee, pain center, clinical hospital of the school of medicine, usp, são paulo, sp, brazil ph.d. in neurology; pain center coordinator, department of neurology, clinical hospital of the school of medicine, usp, são paulo, sp, brazil ph.d. student in neurology; attending physician, pain center and functional neurosurgery, clinical hospital of the school of medicine, usp, são paulo, sp, brazil m.d.; residence in orthopedics; musculoskeletal outpatient clinic coordinator, pain center, clinical hospital of the school of medicine, usp, são paulo, sp, brazil failed back surgery pain syndrome: therapeutic approach descriptive study in patients rev assoc med bras ; ( ): - introduction according to the international association for the study of pain (iasp), the post-laminectomy syndrome is defined as a “low back pain of unknown origin, persisting at the same location as the original pain despite operative interven- tions or with a post-surgery onset. the low back pain may be associated with a referred or radiating pain” . this defi- nition applies to all surgeries designed to treat pain arising from the low back spine, including those aiming to treat a herniated disk. surgical management applied to herniated disks is a hemilaminectomy with a flavectomy, nerve root dislocation and a hernia excision. the many clinical mani- festations of the post-laminectomy pain often overlap and have a low back pain as a common expression. the term “unknown origin” in the definition should not be strictly used, as although the post-laminectomy syndrome is com- plex and the pain can arise from various nosological enti- ties affecting varied anatomical elements in the spine or away from the spine or even being a result from systemic conditions, its origin can be found in many cases . low back pain causes are varied and differential diag- nosis is wide. the structure causing the pain is identified in less than % of cases . the herniated disks are the most common indication for laminectomy to treat low back pain. over thousand laminectomies are estimated to be carried out in the united states, with a failure rate high- er than % . misinterpretation of pain origin as resulting from a herniated disk seen in imaging studies , misidenti- fication of spine instability and other mechanical causes, including incomplete removal of the herniated disk , and operative complications are blamed for the poor surgical results . pain can also result from articular facet instabil- ity or from reduced intervertebral space due to structure abnormalities or intervertebral disk removal, with conse- quent change in the articular facet angle . among non-me- chanical causes for the failed back surgery pain syndrome, disk infection, peridural “fibrosis”, arachnoiditis and psy- chosocial factors should be mentioned . in this study, we aimed to assess the clinical features and the non-surgical management outcome in patients with a failed back sur- gery pain syndrome seen in a pain center. methods fifty-six patients diagnosed with a failed low back surgery pain syndrome were prospectively followed over one year at the neurological clinic pain center of the clinical hos- pital of universidade de são paulo in a descriptive study. the design was approved by the institutional ethics board ( / ). every patient signed an informed consent form. patients with a persisting low back pain or an early relapse within less than three months of a surgical herniated disk procedure were selected. the patients were admitted into a specific postoperative low back pain outpatient clinic according to a spontaneous demand in the unit. patients with evidence of metabolic, inflammatory, and oncologi- cal diseases or a radiological segmental instability picture were excluded. no patients experienced a cognitive im- pairment. out of patients admitted into our unit, were excluded by exclusion criteria and the follow-up was lost in three cases. we obtained data from history, general physical exam, neurological and physiatric evaluation in addition to pre- and postoperative imaging studies. lab- oratory tests to rule out rheumatic or metabolic diseases (ana, rf, esr, crp, blood cell count) were performed. the pain magnitude, characteristic, nature and location, as well as the radiating course in pre- (retrospectively) and postoperative periods. the pain intensity was assessed according to a visual analog scale (vas) before and after treatment. the physiatric exam aimed specially to assess low back spine and paravertebral, low back, gluteal and lower limb muscle groups, consisting of muscle power as- sessment, miofascial trigger point presence, spasms, sen- sitivity, cutaneous changes, and trophism. data collection was performed by using a standard protocol. the statistical analysis used sigmastat software. for all patients, a drug therapy with a rehabilitation program using kinesiotherapy and muscle stretching was adopted and if a rehabilitation refractory myofascial com- ponent (mps) was associated, these patients underwent needling with a % lidocaine injection. mps was identified in ( . %) patients. drug therapy consisted of amitrip- tyline to  mg/day (mean,  mg/day), chlorproma- zine to  mg/day (mean,  mg/day), naproxen to   mg/day (mean  =    mg/day), acetaminophen to   g/day (mean  =  . g/day) and codeine phosphate to  mg/day (mean =   mg/day) according to the requirements and tolerability in each case. all patients un- derwent physiatric follow-up. in case there was not ≥  % original pain improvement (vas) all over the follow-up, the patients were considered frankly refractory, undergoing a  ml infusion containing morphine   mg/ml and % lidocaine by catheter place- ment into the low back peridural compartment bid over two weeks. results overall, ( . %) patients were male and their ages ranged from to years (mean, . years ±  . years). the patients’ mean age at the original pain onset ranged from to years (mean =  . years). the patients had undergone from one up to four low back laminectomies (mean =  . ) to treat low back pain or lumbosciatic pain. the mean symptomatology length was months. the length of the low back pain or lumbosciatic pain complaints ranged from to months (mean  =  months). regarding the pain intensity, the patients with a radiculopathy persisting postoperatively were found with a higher pain score by the pain analog scale. those manoel jacobsen teixeira et al. rev assoc med bras ; ( ): - muscle n % lumbar quadrate gluteus medius gluteus minimum piriform total n, absolute numbers; %, percentage. table – patient disposition according to muscles affected more severely by the myofascial pain syndrome muscle n % gluteus medius gluteus minimum lumbar quadrate , piriform , vastus lateralis vastus medialis gastrocnemius levator ani mps, myofascial pain syndrome table – affected muscle distribution by mps satellite or secondary trigger points with a postoperative root pain diagnosed had a mean score of . , compared with . for those with no radiculopathy (p =  . ). in ( . %) patients, the preoperative pain history was consistent with a root origin, in ( . %) with re- ferred pain in musculoskeletal conditions in both lower limbs, in ( , %) with referred pain in one lower limb, in ( . %), the pain location was only the lower back re- gion and in ( . %) the pain had polyneuropathy char- acteristics. three ( . %) patients who did not experience pain with root characteristics preoperatively had under- gone a diskectomy and spinal fixation. x-ray studies disclose a one- or two-lumbar-segment hemilaminectomy unilaterally (l or l ) in ( . %) pa- tients and bilateral lumbar laminectomy in ( . %). the lumbar spine dynamic study did not show instability in any patient. the computed tomography (ct) scan or mag- netic resonance (mr) imaging did reveal a periradicular scar at the operative site in ( . %) cases. the pain intensity before the operations ranged from moderate to severe, according to the vas, scoring from to (mean =  . ); the pain intensity at the first attendance to the pain center, clinical hospital, universidade de são paulo was severe, scoring from to (mean =  . ). thirty-six patients ( . %) had undergone physical therapy, ( . %) had been on nonsteroidal anti-in- flammatory drugs (nsaids), and ( . %) had been on corticosteroids alone or in combination with b complex vitamins, four ( . %) had been on opiates, and five ( . %) had been on tricyclic antidepressive agents before and af- ter the surgery. all of the patients had stayed at rest and those exerting an occupational activity had been put away from work. in ( . %) patients, uniradicular ( . %) or mul- tiradicular ( . %) syndromes were shown. ten ( . %) patients had muscle pain and myofascial painful points in several body regions, sleep disturbances and depression, suggesting the fibromyalgia syndrome. trigger points characteristic of mpss were identified in ( . %) patients. out of ( . %) patients with preoperative nerve root pain, ( . %) had lumbar or gluteal mpss (table  ). satellite or secondary trigger points were found in ( . %) patients (table  ). the treatment outcome was rated as excellent (>  % improvement over the original pain according to the vas), good ( % to % improvement), fair ( % to <  % im- provement) and poor (<  %). drug therapy combined with physical rehabilitation measures provided an excellent outcome in ( . %) pa- tients, a good outcome in ( . %), a fair outcome in ( . %) and a poor outcome in ( . %). in patients, mps was found and trigger point in- jections were performed by using % lidocaine .   ml. by comparing the pain improvement scores, patients with mps had worse outcomes over post-laminectomy syn- drome without mps. the immediate results were excellent in ( . %), good in ( . %), fair in ( . %) and poor in ( . %). the results were satisfactory for . % of patients with mps versus % in patients without mps, but the difference was not statistically significant (p =  . ). at the end of treatment, significant improvement (ex- cellent and good outcomes) occurred in ( . %) pa- tients, while ( . %) had a fair outcome. however, the outcome was considered poor in ( . %) patients. re- garding the pain intensity at the final follow-up, we found a reduced general mean in the visual analog scale from . to . (p =  . ). a peridural catheter for spinal infusion of a morphine and lidocaine solution was placed in thirteen patients; all of them had a mps, being considered refractory after a re- habilitative treatment attempt. the outcome was excellent in ( . %) patients, good in ( . %), and poor in ( . %), meaning the outcome was excellent or good in ( . %) patients treated with a peridural infusion. discussion low back pain is present at some point in life and con- stitutes a serious public health problem in % to % of individuals . treatment cost, compensation, and lost pro- ductivity are high. the patients’ mean age at pain onset was . years, with the individuals within this age group usu- ally exercising their occupational activity to a very great extent. failed back surgery pain syndrome: therapeutic approach descriptive study in patients rev assoc med bras ; ( ): - in most cases, the course is favorable, even when no care measures are taken. however, low back pain becomes chronic in % to % of individuals . in . % of patients studied by frymoyer , the pain lasted more than two weeks and in % it was severe. in . % of deyo and tsiu’s patients , the pain was mild; in . %, it was moderate and in %, severe; in % of cases, the low back pain irradi- ated to lower limbs and in only % a true sciatic pain could be found. in our series, preoperative pain was severe, with a . score according to the vas; . % had a low back pain and referred pain to lower limbs history before the surgery. in only . %, the history suggested a true sciatic pain, and these findings indicate selection criteria for the surgery were likely inappropriate in most cases. according to hanley et al. , the operative treatment outcome of herniated disks is poor in % of cases. the numbers of spine surgeries to relieve pain have steadily grown in the united states, with thousand operations in , , in reaching , in , with thousand cases of failed back surgery pain syndrome per year . according to deyo and tsiu , the main reason for an increasing number of laminectomies is the growing number of surgeons operating the spine in each country. in different countries and different regions, the frequency of operation indications is variable, and this is not ex- plained only by the different prevalence of low back pain or lumbosciatic pain; in % or % of individuals, herniated disk surgeries are indicated in the usa, but only in % of individuals in sweden and denmark. poor outcome of operative treatment might result from an incorrect diagnosis. among the identified causes for low back pain, the following could be highlighted: rheu- matic conditions, primary or secondary spine tumors, vascular conditions, hematological abnormalities, en- docrine conditions, pelvic or abdominal viscus diseases (endometriosis, ovarian cyst torsion, pelvic inflammatory disease, prostatitis, cystitis,  pancreatopathy, nefropathy, kidney disease, peptic ulcer, urinary tract, biliary or duo- denal conditions), mechanical abnormalities (herniated in- tervertebral disk, articular facet injury, segmental instability or sacroiliac joint instability), systemic conditions (fibromy- algia, myositis, autoimmune or immune-allergic diseases), psychiatric diseases and other conditions (hip joint disease, trochanteric bursa injury, polyradiculoneuritis, meningeal irritation signs) . because of the great number of possibili- ties, the high surgical therapeutic failure rate is justifiable in care provided to these patients, but it also indicates there must be a more judicious semiologic evaluation. surgeries that do not meet the indication criteria to treat a herniated disk can result in maintenance or wors- ening of pain and preoperative deficits. a herniated disk misinterpreted as a cause for low back pain is the most common reason for indicating spine surgeries that prog- ress to a post-laminectomy chronic pain syndrome with an early onset postoperatively. this is partly due to over- valuing the anatomical findings not related to the low back pain that are shown in imaging studies, but those usually do not warrant the pain and the surgical intervention . in % of asymptomatic individuals studied by hitselberg and wihen , the x-ray imaging revealed abnormalities suggesting a herniated disk. in % of asymptomatic in- dividuals studied by wiesel et al. , a spine ct scan found abnormalities; in . % of cases, there was a herniated disk evidence. boden et al. observed % of asymptomatic in- dividuals had a herniated disk on magnetic resonance im- aging. therefore imaging studies can confirm a herniated disk clinical diagnosis, but they are not the main determi- nants for indicating a surgery, since asymptomatic herni- ated disks are so commonly seen . even in symptomatic conditions, there is a progressive absorption of the herniated disk fragment, a phenomenon accompanied by symptom improvement in most cases . hakelius observed % of patients with a herniated disk not undergoing a surgery, but having been on medical treatment, were clinically improved within a month, % within two months, and % within three months. saal and sall conducted a retrospective study involving patients with a radiculopathy resulting from a herniated disk; underwent a conservative treatment, resulting in improvement in over % of cases; only in three cases surgical ablation of extruded fragments was required. this means the indication criteria for diskectomy, represented by a cauda equina syndrome, marked acute or progressive motor deficit or lumbosciatic pain occurrence and evident radiculopathy, characterized by sensory, motor and deep tendon reflexes deficits over one or more nerve root ter- ritory, nerve root irritation evidence, translated as a posi- tive straight leg raising maneuver and consistent imaging study findings in patients achieving no improvement after symptomatic drug therapy with physical medicine measures during a period of over to weeks , , are not always met. only . % of patients included in the current casuistry had undergone physical medicine treatment and only . % had undergone a tricyclic antidepressant thera- py before the operations, suggesting medical methods had not been adopted in most cases. mechanical causes are responsible for % of post-lam- inectomy pain cases . among them, residual or relapsed herniations, spinal instability, post-vertebral fixation pseud- arthrosis, articular facet abnormalities, spinal canal stenosis, meningocele and pseudomeningocele are highlighted . in no patient of ours a spinal instability or residual herniation was found. in addition to the diskectomy, a spinal fixation and fusion was proposed . however, there is little evidence the spinal fusion is useful in patients with no actual spinal instability . this occurred in . % of study subjects. postop- erative imaging of a residual disk herniation does not imply this is necessarily the cause for a persisting pain, as postop- manoel jacobsen teixeira et al. rev assoc med bras ; ( ): - erative imaging studies often show similar abnormalities in individuals whether they are symptomatic or not . peridu- ral scar occurring after a laminectomy is a frequent post- operative finding. newly formed tissue can involve, distort and/or compress the nerve root. however, epidural fibrosis is often shown on ct scan or mri postoperatively in cases there is no pain . in . % of patients in this study, a perira- dicular scar was found. the patients included in our study had undergone up to surgical lumbar spine surgical procedures with no im- provement; the mean was . operations per patient. many patients undergoing further operations to treat persisting or residual pain get frustrated. the improvement rate in reoperations is low, around % after the second surgery, % after the third surgery and % after a fourth proce- dure with up to % of worsening . out of patients analyzed in the present study, , % had mps not found previously on physical exam. there is evidence that mps is involved in low back pain genesis or maintenance . however, mps diagnosis is frequently dis- regarded . many lumbar muscles affected by mps and the operative injury would result in pain worsening. although physiatrically speaking lumbar and gluteal muscle mps is considered the most important cause for low back pain, bone, tendinous, nerve, disk and bursa conditions are still valued as symptom causes . the muscle fiber injury is not necessarily a cause for pain, since in patients with primary degenerative conditions, as in duchenne muscular dystro- phy, there is a disruption in a large amount of myofibrils and the sarcoplasmic reticulum, but there is no pain, sug- gesting mps symptoms result from nonstructural muscle fiber changes or dysfunctions . the main electrophysio- logical abnormality seems to be a neuromuscular dysfunc- tion in the motor endplate. the energy crisis theory postulates there is an increased calcium concentration in the sarcoplasm due to a sarco- plasmic reticulum, sarcolemma and or muscle cell mem- brane disruption. the sarcoplasmic reticulum function is storing and releasing ionized calcium, which activates contractile elements and causes sarcomere shortening. sustained sarcomere contraction results in increased me- tabolism, causes localized ischemia and generates a local- ized energy crisis. the combination of electrophysiological and histopathological theories generated the neuromus- cular endplate multiple dysfunction concept. the poten- tials recorded as spontaneous activity or spikes in trigger points would result in abnormal acetylcholine release by the nervous ending. acetylcholine release would accentu- ate depolarization and calcium release from the sarcoplas- mic reticulum, causing sarcomere contraction and small- caliber vessel compression. increased depolarization due to acetylcholine release and sarcomere contraction would cause increased energy demand, which, if associated with hypoxia resulting from reduced muscle blood flow, would then cause the energy crisis. this energy crisis generates metabolites which sensitize nociceptores and referred pain from trigger points . the abnormalities in nerve fibers re- sponsible for supplying the muscle could cause localized muscle contraction and mps . the referred pain from the trigger point is due to a sensory neuron sensitization in the spine cord posterior horn and may have a distribution similar to that in the radiculopathic pain. this referred pain associates with tingling and numbness . in . % of patients with preoperative nerve root pain history, lum- bar and gluteal mps was identified. the ages of patients included in the study when firstly seen at the pain center ranged from to years (mean age, . years). the mean symptom length was months and the mean pain intensity was . , showing the magni- tude and the extended distress the patients went through. the postoperative pain was also shown more severe than the preoperative pain. the chronic pain treatment should involve a multi- disciplinary team and pharmacological, physiatric, psy- chotherapeutic, and neuroanesthesic procedures; func- tional neurosurgical procedures should be performed if required . the treatment with analgesic drugs, whether they are anti-inflammatory drugs or not, psychotropic drugs and physical medicine provided >  % original pain improvement in . % of patients evaluated in this study. myofascial trigger point treatment consists of using analgesic drugs, psychotherapeutic agents, muscle relax- ant drugs, refrigerant vapor, dry needling, local anesthetic injection and stretching, as well as correction of causal or perpetuating factors . in . % of patients undergoing administration of a morphine and lidocaine solution via peridural route in our study, the original pain had >  % improvement. the pain in patients with failed back surgery pain syn- drome is severe, affects individuals in the fullness of their activities, is often found as a lumbar and/or gluteal mps and, less frequently, has a neuropathic pattern alone or as- sociated with mpss . conclusion the failed back surgery pain syndrome evaluation and management is challenging for the medical team. analgesic drugs and physical medicine provide major improvement in most cases. the pain intensity in post-laminectomy syn- drome is worse than the herniated disk preoperative pain. the injection of myofascial trigger points and opiate infu- sion into the lumbar spine compartment can be required in refractory pain cases. references . merskey nb. classification of chronic pain: descriptions of chronic pain syndromes and definitions of pain terms prepared by the in- ternational association for the study of pain. nd ed. seattle: iasp press; . failed back surgery pain syndrome: therapeutic approach descriptive study in patients rev assoc med bras ; ( ): - . follett, ka, dirks ba. etiology and evaluation of the failed back sur- gery outcome. neurosurg q. ; : - . . saal js, franson rc, dobrow r, saal ja, white 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via special section contributions, i.e. horizon papers, switch monitor, stockholm water perspectives, science career, technology career, project updates, symposium watch and web alerts. the public is usually somewhat informed about environmental problems. however, people do not fully understand the basis of these problems or how to deal with them in a sustainable way. sustainable development is a pattern of resource use that aims to meet human needs while preserving the environment so that these needs can be met not only for the present, but also for the future generations. resb presents researchers, practitioners and senior manag- ers with science, technology and engineering to support and enable sustainable development. resb started in , at the time environmental science and technology focused on pollution of organic and inorganic compounds as threats to the environment and our natural heritage. the contribu- tions mainly dealt with the human impact on the environment and scientific solutions for sustainable development. contributions related to the human impact on the environment covered many aspects of interaction between humans, natural resources, eco- systems, special climates or unique geographic zones, and the earth. manuscripts have covered water, air and soil pollution, soil deterioration, pesticides pol- lution, water resources, global warming, energy crisis, sea level rise, tropical deforestation and coral reef whitening. resb also published on a spectrum of scientific solutions for sustainable development, such as pollution prevention, waste minimization, reuse and recycling, green chemistry, new energy and p. n. l. lens (&) pollution prevention and control core, unesco-ihe, po box , da delft, the netherlands e-mail: p.lens@unesco-ihe.org rev environ sci biotechnol ( ) : – doi . /s - - -x resource sources, energy and resource conservation, sustainable ecosystems and environmental biotechnology. over the years of publishing resb, pollution prevention and control is still very high on the agenda, especially in developing countries where there still a huge need for cheap effective technol- ogies. however, several shifts in focus have been observed and new themes have emerged: climate change, energy, biomaterials and nanotechnology. the keywords people, planet and profit that were launched to enable environmental sustainability are tempered by a new pressure of our society onto the natural environment: the depletion of natural resources. our environment and much of our natural heritage is now under threat from unprecedented population growth and economic development. in contrast to economic growth, our environment suffers to sustain these developments. proper resource man- agement is the central issue and a challenge for mankind, not only technological but also sociologi- cal. indeed, there is growing understanding that the environmental challenges facing mankind cannot be solved solely by means of technological or societal sciences. a complex approach is needed, an approach that combines the strengths of novel developments in clean technologies and political implementation of the societal demands for sustainable development and clean environment. environmental problems such as pollution or green house gas emissions are just symptoms of a much deeper issue: our inability to live sustainable. the scale of these problems should, however, not paralyze us into inaction. it should raise our awareness and encourage us to develop new, more sustainable patterns of living, growing, produc- ing and consuming. ultimately, we are talking about revaluing the fundamental elements of life. at times where money markets are looking for direction, the environment can show the way. resb thus contributes to communicating and disseminating the necessary answers to the questions mankind faces. we are convinced that providing broader access to the research findings and informa- tion about environmental pollution and sustainable development will be beneficial for a wide audience in academia, industry and authorities. we are therefore grateful that in its years of publication, resb has developed into a worldwide journal. both its author- ship and readership are spread all over the globe. almost as many authors from asian countries contribute to the journal as compared to those from europe and us. we look forward to the work on resb in the coming years and are confident that resb will continue to help in providing the neces- sary answers to the questions we face in our time. we would like to thank all former and current members of the editorial board for their support and efforts in the development of resb. especially the special feature editors have played a crucial role in the diversification of resb and took resb a step further towards a premier league environmental science and technology journal. we are also grateful to the guest editors that have edited a special issue, these have also significantly contributed to the development of resb. finally, we wish to thank all staff of springer verlag, formerly kluwer aca- demic publishers, for their enthusiastic and stimulat- ing support, first with the establishment of the journal and later with the consolidation of this journal as a key journal in the environmental science and (bio)technology field. delft, february th piet lens editor-in-chief on behalf of the editorial board open access this article is distributed under the terms of the creative commons attribution noncommercial license which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. rev environ sci biotechnol ( ) : – 	 th anniversary of resb 	open access << /ascii encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (gray gamma . ) /calrgbprofile (srgb iec - . ) /calcmykprofile (iso coated v % \ eci\ ) /srgbprofile (srgb iec - . ) 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pass solar air heater with thermal energy storage journal of king saud university – engineering sciences ( ) , – king saud university journal of king saud university – engineering sciences www.ksu.edu.sa www.sciencedirect.com original article experimental study on double pass solar air heater with thermal energy storage s.s. krishnananth, k. kalidasa murugavel * centre for energy studies, national engineering college, k.r. nagar , tamil nadu, india received january ; accepted may available online may * e pe ht keywords solar air heater; thermal storage; paraffin wax; experimental analysis corresponding author. . -mail address: kali_vel@red er review under responsibilit production an - ª king saud u tp://dx.doi.org/ . /j.jksu tel.: + iffmail.co y of king d hostin niversity es. . abstract a double pass solar air heater was fabricated and integrated with thermal storage system. paraffin wax is used as a thermal storage medium. the performance of this heater was studied for different configurations. the solar heater integrated with thermal storage delivered comparatively high temperature. the efficiency of the air heater integrated with thermal storage was also higher than the air heater without thermal storage system. the study concluded that the presence of the thermal storage medium at the absorber plate is the best configuration. ª king saud university. production and hosting by elsevier b.v. all rights reserved. . introduction energy crisis and global warming lead to find an alternative way to overcome the above worsening situation. renewable energy plays a major solution and thereby meets our energy de- mand and reduces the co emission which reduces the green- house effect. in the renewable energy side, sun is the mother for all sources and harnessing the solar energy in proper ways can eliminate the energy crisis of the world. to harness the solar energy, collectors are used and for low temperature application side flat plate collectors are used. in solar air heater, solar en- ergy is collected by means of an absorbing plate and the col- ; fax: + m (k. kalidasa murugavel). saud university. g by elsevier . production and hosting by elsev . lected heat energy is transferred to heat transferring medium such as air. number of researches is going on to improve the perfor- mance of the air heater by integrating flat plate collector with packed bed and energy storage systems. the packed bed with iron turnings (cheema and mannan, ), crushed glass (collier, ), slit and expanded aluminium foils (el-wakil et al., ; shoemaker, ), wire mesh screens (ahmad et al., ; prasad and saini, ; sharma etal., ), hollow spheres (swartman and ogunlade, ), iron chips, alumin- ium chips and pebbles (mishra and sharma, ), and rings made of hard plastic (demirel and kunc, ) were used to in- crease the performance of the air heaters. mittal and varshney ( ) investigated the performance of the heater with wire mesh as packed bed and found that the thermal gain was rela- tively higher as compared to smooth collectors. el-sebaii et al. ( ) investigated the double pass solar collector with iron packed bed and found that the efficiency of the system was – % higher than that of the system without packed bed. the heat transfer and friction characteristics of packed bed so- lar air heater were investigated by prasad et al. ( ) using wire mesh as packing material and found that the lowest value ier b.v. all rights reserved. mailto:kali_vel@rediffmail.com http://dx.doi.org/ . /j.jksues. . . http://www.sciencedirect.com/science/journal/ http://dx.doi.org/ . /j.jksues. . . nomenclature m mass flow rate, kg/s cp specific heat capacity of air, j/kg.k t temperature, k i solar radiation intensity, w/m a area, m subscript o outlet i inlet table physical parameters of solar air heating systems. s. no. design materials/ parameters specifications collector . tilt angle � ’ (south facing) . glass area . m . collector glazing window glass with mm thickness . absorber plate width: mm, length: mm s.s. krishnananth, k. kalidasa murugavel of porosity leads to better performance and heat transfer coef- ficient increases with a decrease in porosity. aldabbagh et al. ( ) investigated that the single and double pass solar air heaters with wire mesh as packed bed achieved . % efficiency for single pass solar air heater and . % for double pass solar air heater. omojaro and aldabbagh ( ) investi- gated the single and double pass solar air heaters with wire mesh as packed bed and observed that efficiency increases with an increasing air mass flow rate. for the same flow rate, the effi- ciency of the double pass was – . % higher than that of the single pass. enibe ( ) analysed the natural circulated solar air heater with phase change material energy storage system and pre- dicted the performance. jain and jain ( ) analysed the in- clined multi pass solar air heater with in-built thermal storage on deep-bed for drying application and found that the bed moisture content decreases with the time of the day and also the drying rate increases with the increase in the depth of drying bed. mahmud et al. ( ) studied the solar air col- lectors with thermal storage units and found that the pcm with high latent heat were required for optimum thermal per- formance of solar air heater. in this work, a double pass solar air heater was fabricated and tested with energy storage system. paraffin wax in cylindri- cal capsules is used as phase change energy storing material. experiments were conducted and performances were com- pared for different configurations. in each configuration, the paraffin capsules were placed in different locations. . bottom plate width: mm, length: mm . bottom insulation mm thickness of glass wool . side insulation mm thickness of glass wool storage material . pipe, inner diameter cm . pipe, outer diameter . cm . pipe length cm . total no. of pipes . weight paraffin per capsule . kg. . experimental setup a double pass solar air heater of mm length, mm width and mm height was fabricated using mild steel plate as shown in the fig . to reduce the heat losses to the atmo- sphere, the collector bottom and lateral sides were insulated with mm thick glass wool and to reduce convective losses, the collector top side was covered with a mm glass plate. figure schematic diagram for to maintain a uniform distributed flow inside the collector, a conical inlet and exit sections were provided. using a blower, the air was forced through the upper channel in the double pass collector between the top glass cover and the absorber plate and then recirculated in opposite direction through the lower channel between the absorber plate and back plate. the heater was tilted with an angle of � ’ (local latitude angle) with respect to the horizontal position facing south direction to receive the maximum solar radiation. the detailed technical specification of the collector and the pipes used for thermal storage are listed in the table . to improve the system performance, the thermal storage system i.e. phase change material was integrated with double pass solar air heater. paraffin waxes in the six aluminium capsules (each cm diameter and cm length) were used to store the excess thermal energy. the absorber plate and alu- minium capsules are painted with black colour to absorb max- double pass solar air heater. figure position of thermocouples. table accuracies and errors for various measuring instruments. s. no. instrument accuracy range % error thermometer ± �c – �c thermocouple ± . �c – �c . pv type sun meter ± w/m – w/m . u-tube mano meter scale ± mm – figure photograph of double pass solar collector. experimental study on double pass solar air heater with thermal energy storage imum solar radiation. the capsules are arranged in different configurations on the absorber plate and on the back plate. blower is connected to the inlet of the air heater through a gate valve, orifice meter and u-tube manometer. gate valve is used to control the mass flow rate of air and u-tube manom- eter is used to find out the mass flow rate by measuring the head difference across the orifice. to measure the inlet and exit air temperatures, absorber plate temperature and back plate figure configuration , capsu temperature, k type thermocouples were placed at different locations as shown in the fig. and connected to the digital indicator. sun meter is used to measure the solar radiation intensity (table ). the photograph for the double pass solar air heater exper- imentation setup integrated with thermal storage medium was shown in the fig . . experimental procedure experiments were conducted with solar air heater for four dif- ferent configurations. in configuration , no thermal energy storage system was used, where as in other configurations the capsules were placed in different places in line with flow direction. in configuration (fig. ), the capsules are placed above the absorber plate, in configuration (fig. ), the cap- sules are attached below the absorber plate and in configura- tion (fig. ), the capsules are placed above the back plate. experiments were conducted on different configurations of double pass solar air heater from am till evening pm dur- ing march–may at energy park of the national engi- neering college, k.r. nagar ( o ’n, o ’e), india. the solar radiation, temperature and manometer readings were les above the absorber plate. figure configuration , capsules below the absorber plate. figure configuration , capsules above the back plate. t em pe ra tu re ( c ) timeof the day (hr) outlet below glass plate below absorber inlet above glass above absorber figure variations of different temperatures for configuration on th may . s.s. krishnananth, k. kalidasa murugavel observed and recorded for every one hour. for each configura- tion, the readings were taken for two or three days. the obser- vations on these days of similar radiation conditions were considered for analysis. . results and discussion the average solar radiation intensity and atmospheric temper- ature variations during the experimental period were as shown in fig. . the maximum solar radiation intensity recorded was w/m at : pm. from the morning till the evening, the ambient temperature was between and �c and the mass flow rate was estimated by using u-tube manometer as . kg/s. the typical variation of different temperatures of solar air heater with configuration was as given in fig. . the varia- tion pattern was similar for all configurations. all the temper- atures were varying with radiation intensity. the absorber plate is the hottest part in the air heater and it reached �c around noon. the glass also reached the maximum tempera- ture with absorber plate during noon. the exit air temperature closely varied with capsule surface temperature. the exit air temperatures reached a maximum value of �c around noon. s ol ar r ad ia ti on i nt en si ty ( w /m ) time of t solar radiaiton intens ambient temperature figure solar radiation intensity and atmosph only after am, there was an appreciable rise in all temper- atures and after pm all temperatures reached the low value. fig. compares the exit air temperature for different config- urations. when there is no energy storing material, the maxi- mum temperature reached by the air is comparatively less and during the evening there was a high fall rate in the temperature. a m bi en t te m pe ra tu re ( o c ) he day (hr) ity in w/m eric temperature variation on th may . t em pe ra tu re ( o c ) time of the day (hr) figure exit air temperature for various configurations. experimental study on double pass solar air heater with thermal energy storage for configuration , better performance was observed. the air was maintained maximum from am to pm. thermal efficiency of solar air heater is determined from the following equations: g ¼ mcpðto�tiÞ ia the efficiency of the solar air heater was calculated using the radiation received by the heater and the enthalpy rise of the air. the variation in efficiency for different configurations is gi- ven in fig. . when no energy storage system was used, the efficiency was proportional to the radiation received. when en- ergy storage material was used, the excess energy stored in the morning was released during evening. hence the efficiency of the air heater with energy storage materials is higher and effi- ciency increased during evening hours. the solar air heater e ff ic ie nc y ( % ) time of the day (hr) figure efficiency variation. (prasad et al. ) (omojaro et al. ) e ff ic ie nc y (% ) time of the day (hr) configuration previous work with steel wire mesh as absorber previous work with steel wire mesh as packed bed figure comparison with previous work. with configuration , with capsules on the absorber plate was having better performance over others. fig. compares the efficiency of this air heater with con- figuration with some of the previous works carried out by prasad and saini ( ) and omojaro and aldabbagh ( ). it is observed that, the efficiency of the air heater with energy storage and packed bed was better during evening hours. . conclusions a detailed experimental study was conducted to evaluate the performance of the double pass solar air heater with various configurations under the metrological conditions of k.r. nagar ( o ’n, o ’e), tamil nadu, india. paraffin wax with alu- minium capsules was used as phase changing energy storing material. experiments were conducted to study the performance of the air heater with and without energy storage materials. from the experimental results, it was observed that, the so- lar air heater with paraffin wax as energy storage material delivers comparatively high temperature air throughout the day. the efficiency is also higher during evening hours. the double pass solar air heater with capsules placed on the absor- ber plate is the efficient one. references ahmad, a., saini, j.s., varma, h.k., . thermo hydraulic performance of packed bed solar air heaters. energy convers. manag. , – . aldabbagh, l.b.y., egelioglu, f., ilkan, m., . single and double pass solar air heaters with wire mesh as packing bed. energy , – . cheema, l.s, mannan k.d, . performance of parallel flow packed bed air heaters. in: proceedings of ises silver jubilee congress, atlanta, ga, pp. – . collier, r.k, .the characterization of crushed glass as a transpired air heating solar collector material. in: proceedings of ises silver jubilee congress, atlanta, ga, pp. – . demirel, kunc, . thermal performance study of a solar air heater with packed flow passage. energy convers. manage. , – . jain, dilip., jain, rajeev.kumar., . performance evaluation of an inclined multi pass solar air heater with in-built thermal storage on deep-bed drying application. j. food eng. , – . el-sebaii, a.a., aboul-enein, s., ramadan, m.r.i., el-bialy, e., . year round performance of double pass solar air heater with packed bed. energy convers. manage. , – . el-wakil, m.m., duffie, j.a., chiou, j.p., . a slit and expanded aluminium foil matrix solar collector. sol. energy , – . enibe, s.o., . thermal analysis of a natural circulation solar air heater with phase change material energy storage. renewable energy , – . mahmud, m., alkilani, sopian, k., alghoul, m.a., sohif, m., ruslan, m.h., . review of solar air collectors with thermal storage units. renewable sustainable energy rev. , . mishra, c.b., sharma, s.p., . performance study of air heater packed-bed solar energy collector. energy , – . mittal, m.k., varshney, l., . optimal thermohydraulic perfor- mance of a wire mesh packed solar air heater. sol. energy , – . omojaro, a.p., aldabbagh, l.b.y., . experimental performance of single and double pass solar air heater with fins and steel wire mesh as absorber. appl. energy , – . s.s. krishnananth, k. kalidasa murugavel prasad, r.k, saini, j.s, . comparitive performance study of packed bed solar air heaters. in: proceedings of the eighth isme conference, iit, delhi, india, pp. – . prasad, s.b., saini, j.s., singh, k.m., . investigation of heat transfer and friction characteristics of packed bed solar air heater using wire mesh as packing material. sol. energy , – . sharma, s.p., saini, j.s., varma, h.k., . thermal performance of packed bed solar air heaters. sol. energy , – . shoemaker, m.j., . notes on solar collector with unique air permeable media. sol. energy , – . swartman, r.k., ogunlade, o., . an investigation on packed bed collectors. sol. energy , – . 	experimental study on double pass solar air heater with thermal energy storage 	 introduction 	 experimental setup 	 experimental procedure 	 results and discussion 	 conclusions 	references medium-chain fatty acids as biomarkers of mitochondrial dysfunction in traumatic brain injury ebiomedicine ( ) – contents lists available at sciencedirect ebiomedicine journal homepage: www.ebiomedicine.com commentary medium-chain fatty acids as biomarkers of mitochondrial dysfunction in traumatic brain injury raúl gonzález-domínguez department of chemistry, faculty of experimental sciences, university of huelva, , spain international campus of excellence ceia , university of huelva, , spain doi of original article: http://dx.doi.org/ . /j.ebio e-mail address: raul.gonzalez@dqcm.uhu.es. http://dx.doi.org/ . /j.ebiom. . . - /© the author. published by elsevier b.v a r t i c l e i n f o article history: received september accepted september available online september keywords: dative stress, membrane disruption, failures in energy metabolism and neuronal injury, among other pathological processes. in the current issue of ebiomedicine, orešič et al. ( ) describe the application of a metabolomic platform based on bi-dimensional gas chromatography coupled to high-resolution mass spectrometry (gc × gc-tof-ms) to identify biomarkers in serum samples that could associ- medium chain fatty acids metabolomics traumatic brain injury traumatic brain injury (tbi) is a complex disorder with variable eti- ology and severity that nowadays stands as a major cause of death and disability worldwide, principally among children and young people. de- spite the implementation of intensive care strategies at early stages fol- lowing the injury, long-term morbidity of severe tbi still remains high, and many patients may show significant neurologic sequelae even after recovery, which usually persist for years. for this reason, there is a crit- ical need to get a deeper insight into pathological mechanisms occurring in brain after trauma and discover potential biomarkers that could help in diagnosis, staging disease severity, monitoring disease progression, the identification of complications, as well as the development of better strategies for treatment and rehabilitation after injury. tbi pathology begins with a mechanical brain damage, which is followed by complex and dynamic perturbations in multiple molecular pathways in glia and neurons. thus, holistic approaches such as metabolomics stand out as suitable tools for characterizing these metabolic alterations. metabolo- mics can be defined as the comprehensive study of the entire set of me- tabolites from a cell, tissue, organ, body fluid or organism at a specific time, as well as of the metabolic changes observed in response to a ge- netic or environmental perturbation. however, only a few authors have previously reported the application of metabolomic techniques for investigating tbi pathogenesis, usually by employing nuclear mag- netic resonance ( h-nmr) to study the brain and blood metabolome from different animal models (viant et al., ; bahado-singh et al., a; bahado-singh et al., b). thereby, it was demonstrated that m. . . . . this is an open access article under numerous significant disturbances in tbi might be associated with oxi- ate with disease severity and predict the outcomes of tbi patients. for this purpose, two independent cohorts were enrolled with the aim to validate results obtained in the discovery phase, comprising mild, mod- erate and severe tbi patients as well as orthopedic controls. various metabolomic alterations were detected in serum samples, following the same pattern in all patients but with a proportional degree of change depending on the disease severity, thus suggesting that tbi is character- ized by a specific metabotype. moreover, some of these metabolites could be also associated with patient clinical outcomes, which were then employed to build a predictive model with good accuracy. signifi- cant changes were observed in serum levels of different hydroxyl-acids, sugar-derived metabolites as well as amino acids and related com- pounds. furthermore, many of these metabolites were highly correlated with their content in brain microdialysates, thus evidencing a possible disruption of the blood brain barrier. however, the most relevant find- ing was the increase of two medium chain fatty acids (mcfa), including octanoic and decanoid acids, whose levels remain high in most patients during the first week following the injury, and could be associated with poor outcomes in tbi patients. the accumulation of mcfas, together with their corresponding acyl-carnitines, is the typical feature of medi- um-chain acyl-coenzyme a dehydrogenase deficiency, the most fre- quent fatty acid oxidation disorder, and one of the most recognizable inborn errors of metabolism (rinaldo and matern, ). nevertheless, recent studies have also associated this metabolic signature with other heterogeneous diseases, such as alzheimer's disease (gonzález- domínguez et al., ), schizophrenia (liu et al., ) and different types of cancer (hori et al., ; crotti et al., ), all of them charac- terized by impaired mitochondrial function. furthermore, it has been demonstrated that these fatty acids can provoke significant failures in various pathways related to energy metabolism, including the oxidative phosphorylation and the creatine kinase system, and may elicit lipid and protein oxidative damage (schuck et al., ). thereby, there is considerable evidence that suggests the potential of these circulating mcfas as biomarkers of mitochondrial dysfunction. the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). http://crossmark.crossref.org/dialog/?doi= . /j.ebiom. . . &domain=pdf http://dx.doi.org/ . /j.ebiom. . . http://dx.doi.org/ . /j.ebiom. . . mailto:raul.gonzalez@dqcm.uhu.es http://dx.doi.org/ . /j.ebiom. . . http://creativecommons.org/licenses/by-nc-nd/ . / http://www.sciencedirect.com/science/journal/ www.ebiomedicine.com r. gonzález-domínguez / ebiomedicine ( ) – therefore, it is noteworthy that octanoic and decanoic acids could play a major role in energy crisis associated with mitochondrial failures occurring in traumatic brain injury. however, it remains unclear if these metabolic changes are causative performers of the pathophysiology ob- served or, on the contrary, they are a consequence of these impairments. thus, a better understanding of pathological mechanisms underlying to these perturbations is necessary to obtain a deeper knowledge about the relationships between tbi and medium-chain fatty acids. to this end, future studies should be undertaken with complementary metabolomic approaches such as reversed phase liquid chromatogra- phy-mass spectrometry in order to elucidate the relevance of lipid me- tabolism and fatty acid β-oxidation in pathogenesis of traumatic brain injury. disclosure the author declares no conflicts of interest. references bahado-singh, r.o., graham, s.f., turkoglu, o., beauchamp, k., bjorndahl, t.c., han, b., mandal, r., pantane, j., kowalenko, t., wishart, d.s., stahel, p.f., a. identification of candidate biomarkers of brain damage in a mouse model of closed head injury: a metabolomic pilot study. metabolomics , . bahado-singh, r.o., graham, s.f., han, b., turkoglu, o., ziadeh, j., mandal, r., er, a., wishart, d.s., stahel, p.f., b. serum metabolomic markers for traumatic brain in- jury: a mouse model. metabolomics , . crotti, s., agnoletto, e., cancemi, g., di marco, v., traldi, p., pucciarelli, s., nitti, d., agostini, m., . altered plasma levels of decanoic acid in colorectal cancer as a new diagnostic biomarker. anal. bioanal. chem. http://dx.doi.org/ . /s - - - . gonzález-domínguez, r., garcía-barrera, t., gómez-ariza, j.l., . using direct infusion mass spectrometry for serum metabolomics in alzheimer's disease. anal. bioanal. chem. , – . hori, s., nishiumi, s., kobayashi, k., shinohara, m., hatakeyama, y., kotani, y., hatano, n., maniwa, y., nishio, w., bamba, t., fukusaki, e., azuma, t., takenawa, t., nishimura, y., yoshida, m., . a metabolomic approach to lung cancer. lung cancer , – . liu, m.l., zheng, p., liu, z., xu, y., mu, j., guo, j., huang, t., meng, h.q., xie, p., . gc-ms based metabolomics identification of possible novel biomarkers for schizophrenia in peripheral blood mononuclear cells. mol. biosyst. , – . orešič, m., posti, j.p., kamstrup-nielsen, m.h., takala, r.s.k., lingsma, h.f., mattila, i., jäntti, s., katila, a.j., carpenter, k.l.h., ala-seppälä, h., kyllönen, a., maanpää, h.r., tallus, j., coles, j.p., heino, i., frantzén, j., hutchinson, p.j., menonemail, d.k., tenovuoemail, o., hyötyläinen, t., . human serum metabolites associate with severity and patient outcomes in traumatic brain injury. ebiomedicine , – . rinaldo, p., matern, d., . fatty acid oxidation disorders. annu. rev. physiol. , – . schuck, p.f., ferreira, g.c., moura, a.p., busanello, e.n., tonin, a.m., dutra-filho, c.s., wajner, m., . medium-chain fatty acids accumulating in mcad deficiency elicit lipid and protein oxidative damage and decrease non-enzymatic antioxidant de- fenses in rat brain. neurochem. int. , – . viant, m.r., lyeth, b.g., miller, m.g., berman, r.f., . an nmr metabolomic investiga- tion of early metabolic disturbances following traumatic brain injury in a mammalian model. nmr biomed. , – . http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://dx.doi.org/ . /s - - - http://dx.doi.org/ . /s - - - http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf http://refhub.elsevier.com/s - ( ) - /rf 	medium-�chain fatty acids as biomarkers of mitochondrial dysfunction in traumatic brain injury 	disclosure 	references . .j.jeece. . journal of energy, environmental & chemical engineering ; ( ): - http://www.sciencepublishinggroup.com/j/jeece doi: . /j.jeece. . synthesis and characterization of doped nano heat transfer fluid for concentrated solar power plant huma naveed , , asima siddiqa , * , shahid naseer , , rohama gill , humaira razzaq department of environmental sciences, fatima jinnah women university, rawalpindi, pakistan national centre for physics, nanoscience and technology division, quaid-i-azam university campus, islamabad, pakistan institute of space and technology, islamabad, pakistan email address: a.sam.malik@gmail.com (a. siddiqa) * corresponding author to cite this article: huma naveed, asima siddiqa, shahid naseer, rohama gill, humaira razzaq. synthesis and characterization of doped nano heat transfer fluid for concentrated solar power plant. journal of energy, environmental & chemical engineering. vol. , no. , , pp. - . doi: . /j.jeece. . received: october , ; accepted: january , ; published: february , abstract: with the view to minimize the energy crisis due to the ever depleting non-renewable energy resources, this research aimed to apply nanotechnology to enhance the efficacy of solar energy power plant – a renewable energy resource. according to literature concentrated solar power plant system requires heat transfer fluid (htf) for proficient working. this research reports the synthesis of novel, efficient heat transfer fluid doped with nano sized particle including carbon nanotubes and metal oxide i-e copper oxide. this nano heat transfer fluid (nhtf) has very low melting point in comparison to conventionally prepared molten salt mixture for heat transfer purpose which typically have high melting point characteristically °c or higher. most prominently this nhtf has enhanced thermo-physical properties including high thermal stability and high specific heat capacity. these properties ensures effective increase in thermal energy storage (tes) which is a key factor in solar thermal power plant and make it broad range operating heat transfer fluid. keywords: eutectic, nano heat transfer fluid, specific heat capacity, concentrated solar power . introduction energy is an ultimate irreducible essence of the universe without which life cannot be imagined but today world is facing an acute energy crunch. global energy demand is continuously escalating manifolds due to the fast pace of technological advancements and unequal demographic distributions. the world’s total electricity consumption in the year was , twh which is predicted to rise to , twh by [ ]. this serious energy crisis is mainly attributed to the continuous dependence on fossil fuels which results in the exhaustion of natural non-renewable resources. in addition, the burning of fossils fallout in high carbon dioxide emissions adding to the ever increasing green house gases which ultimately results in global warming. presently top priority of developed countries is exploiting the use of clean renewable energies so as to seek sustainable development because these resources cause less environmental impact. modern nanotechnology provides new opportunities and is expected to play considerable role in reviving the traditional energy industries and invigorating the rising renewable energy industries [ , ]. apart from other innumerable applications of nano- technology, in the field of energy conservation its use in increasing the efficiency of solar power plants by enhancing the heat transfer properties is now gaining momentum. with the aid of nanotechnology, such fluids can be synthesized which proper heat transfer within a system. solvents doped with nanoparticles at minute concentration are termed as nanofluid, a term proposed [ , ]. nanofluids are exemplified as next generation heat transfer fluids as they proffer new exciting possibilities to embellish heat transfer performance in comparison to pure base fluid. these fluids are required to have remarkable and finer thermo-physical properties than conventionally used heat transfer fluid and also the slurries containing milli and micro sized particles the dispersion of milli and micrometer sized particles is prone to sedimentation and clogging in micro-channels. due huma naveed et al.: synthesis and characterization of doped nano heat transfer fluid for concentrated solar power plant to settling problems there is lack of stability of suspensions, which tempt additional flow resistance and possible erosion [ , ]. properly engineered thermal nanofluids possess number of benefits such as nanometric particles have fairly large surface area which not only aids in improving heat transfer capabilities but also significantly improve stability of suspension. small size of nanoparticles perks up the abrasion-related properties. successful employment of nanofluids will result in reduced particle clogging and promoting system miniaturization. so using nanofluids for heat transfer application with enhanced thermo-physical properties allows its effective use in concentrated solar power plant [ ]. preparation of nanofluids is the first key step in experimental studies of nanofluids. nanofluids are not simply liquid-solid mixtures, however special requirements are essential to prepare it, for example, stable and sturdy suspension, negligible agglomeration and clogging etc. so principally they are prepared by using two different methods commonly called as one-step method and two-step method [ , ]. enhancement in different thermo-physical properties is the basic mean to make potent and well operative heat transfer fluid. a lot of work has been done on the thermal conductivity of nanofluids. nevertheless very little research has been done on specific heat capacity but enhancment in specific heat capacity can make heat transfer fluid more effective [ ]. as nanoparticles contribute significantly to the total heat capacity of the nanofluid while they go through a phase transition, during a first order phase transition heat capacity of substance enhances manifold and due to the very large surface area of nanoparticles, the effect of surface charge can be significantly increased and as a result it results in over all stability of the resulting nanoparticle/liquid mixture [ ]. shin and banerjee generated nanofluid by making suspension of silica in alkali chloride eutectic salt as basefluid and reported . % enhancement in specific heat capacity for % concentration by weight [ ]. opposingly, zhou et al found that the specific heat capacity of al o nanoparticles in water decreased by – % at . % volume concentration of al o . most obvious reason for such behavior might be agglomeration of particles [ ]. the aim of this research work was to synthesize nhtf for the application of concentrated solar power plant and to study the effect of nanopaticles on the properties of nhtf. . materials and method all the chemicals were purchased from sigma-aldrich, germany except the multi walled carbon nanotubes (mwcnts) which were manufactured through chemical vapor deposition (cvd) method by patented method [ ]. step : synthesisof eutectic mixture eutectic salt mixture of nano : kno : lino : kcl ( : : : ) was prepared by thoroughly mixing finely ground salts. mixed salts were initially dried at °c to remove moisture. step : synthesis of functionalized cnts raw cnts were purified in order to remove impurities before further processing. mwcnts were heated up to °c for minutes and then sonicated at °c for three hours in sonicator and diluted by water. filtration of solution was carried out using membrane filter paper of pore s . µ using a suction filter apparatus and washed up to neutral ph, then dried at °c for hours. the purified mwcnts were treated with a mixture of sulfuric acid and nitric acid ( : ) and sonicated for hours at °c. the acid treated mwcnts were again diluted and followed by filteration and drying. step : synthesis of copper oxide nanoparticles sol-gel process was used for cuo nanoparticles production, gm of cu(no ) .h o is dissolved into ml of ethanol. it was stirred for hour to obtain the homogeneous solution. and kept for hours so that to allow it to form gel, it was dried at °c and pulverized and calcinated at °c for one hour. step : preparation of nanofluid . and . wt % of each mwcnts and cuo nanoparticles were added in . % sodium dodecyl sulphonate (sds) surfactant solution. gram of eutectic mixture is added to each of mwcnts and cuo solution. these solutions were strongly stirred for at least one hour followed by sonication of mwcnts and cuo sample for half an hour and minutes, respectively. it was observed that on increasing the time of sonication nanoparticles start to segregate. obtained homogenous dispersion was subjected to drying on hotplate at °c. samples were again dried in an oven at low temperature to ensure complete removal of moisture. . characterization melting point was measured by using melting point apparatus (r bibby scientific limited). crystal modality is vital for nano materials. xrd pattern of sample was analyzed with x-ray diffractometer (philips x’pert pro / ) employing cu-kα radiation. scanning electron microscopy (sem) analysis was carried out for morphological studies and was performed using leo feg-semeds. the specific heat capacities of all the materials have been calculated by using dsc results. dsc/tga analysis was carried out using instrument (sdt q. ta instruments, inc.) equipped with computer for control and data handling. the temperature was ramped from to °c at °c/min. . results and discussion the present study was carried out to synthesize nano heat transfer fluid with enhanced thermo-physical properties i.e low melting point, high thermal stability and high specific heat capacity for effective use in concentrated solar power plant system as solar light absorber. journal of energy, environmental & chemical engineering ; ( ): - . . melting point analysis ideally the material used for heat transfer purpose must be liquid at room temperature and conventionally liquid material such as water, mineral oil etc are used but they have low boiling points which make it unsuitable for csp functioning. in this research heat transfer fluid was developed as a result of material screening process, in order to achieve low melting point (so minimum amount of energy is used to convert it into fluid form), eutectic salt mixture was prepared and tested for melting point measurement. it is found that addition of nanoparticles do not alter the melting point of eutectic salt mixture. melting point of prepared sample was very low i.e °c in comparison to literature. the mechanism of lowering melting point by making different eutectic mixture can be attributed to the fact that this mixture tend to disrupt intermolecular forces i-e reducing the variation in enthalpy or to increase the disorder generated upon melting, this lead to melting point reduction [ , ]. . . xrd studies to be ensure about proper synthesis of nanomaterial, xrd of carbon nanotubes and cuo was carried out to look at its crystal structure. the diffraction peak could be attributed to existence of amorphous mwcnts as depicted by figure a. an xrd spectrum for cuo is shown in figure b which exhibit braggs reflection at about °, °, °, ° °, °, °, °, °, ° and ° degrees corresponding to , , , , , , , , , , confirming the crystal planes of cuo nanoparticles [ ]. the average crystalline size of copper oxide was estimated by using scherrer formula which is equal to . nm. figure . x-ray diffraction pattern of (a) functionalized mwcnts (b) cuo nanoparticles. . . sem analysis the micrographs of functionalized mwcnts, cuo, mwcnt doped nano heat transfer fluid, cuo doped nano heat transfer fluid as shown in figure (a-d). it is clearly depicted by the sem micrographs for functionalized mwcnt that mwcnts have a diameter in the range of - nm and also they are de-agglomerated having a clean surface which confirms an effective purification and oxidation treatment [ ] and cuo particles are spherical in nature and also not agglomerated. sem micrographs show its particle size is between the range - nm. huma naveed et al.: synthesis and characterization of doped nano heat transfer fluid for concentrated solar power plant figure . sem micrographs for (a) mwcnts (b) cuo (c) mwcnts doped nano heat transfer fluid (d) cuo doped nano heat transfer fluid. . . thermal stability high thermal stability of heat transfer fluid is the basic requirement and one of most important parameter to make it operative at high temperature in csp system. the tga curve clearly proves the thermal stability of the material at higher temperature. the material does not suffer any significant weight loss till the temperature as high as °c as shown in figure . the minimal weight loss that appears may be because of the moisture [ , ]. however beyond °c thermal degradation of material starts rapidly till °c. thermal stability analysis of eutectic mixture shows that nitrates of alkali metals are quiet stable at elevated temperatures as high as °c [ , ]. the mechanism behind its stability was that as temperature gradually increases nitrate decomposes at high temperature at first and then the decomposition rate of nitrates was slower than the oxidation of nitrites [ ]. therefore thermal stability of nanofluids is mainly because of proper composition of eutectic mixture. figure . tga curve showing thermal stability of nano heat transfer fluid. . . specific heat capacity analysis in order to calculate heat capacity following formula is used: [ , ] cp � � �∆� ( ) where; cp = specific heat, q = heat flow, m = mass, ∆t = change in temperature the enhancement in specific heat capacities of nhtf (containing different percentages i.e. . %, and . % of both multi walled carbon nanotubes and cuo nanoparticles has been observed as shown in figure (a-b). it clearly shows that nanofluids have higher specific heat capacity than undoped material. the anomalous increase the specific heat capacity of nanofluid can be justified as follows; as nanoparticles have a greater surface area per unit volume than larger particles i-e within nano dimension the amount of atom exposed at surface is tremendously high than that of bulk material [ ]. this high surface area results in high rate of reaction in the form of absorption of heat, leading to over all higher surface energy (kinetic energy). moreover; larger surface area cause increase in thermal resistance between the solid nanoparticles journal of energy, environmental & chemical engineering ; ( ): - and fluid particles of molten salt mixture [ , ]. this thermal resistance provides the additional thermal energy storage in the form of increased specific heat capacity [ ]. moreover, the surface energy of whole system increases resulting in effective enhancement in specific heat capacity [ ]. figure . variation of specific heat capacity of pure eutectic and nano heat transfer fluid (a) carbon nanotubes (b) copper oxide nanopartilces with temperature. . conclusion � the research succeeded in achieving enhanced thermo- physical properties by synthesizing an efficient nano heat transfer fluid by doping base fluid with nano sized particle. � designed nanofluid has low melting point, high thermal stability and high specific heat capacity. cnt and cuo are proved to be promising nanomaterial for enhancing these properties. � it is evident from tga results that nanofluid is stable till °c. it has low melting point i.e °c. � from dsc results it is concluded that enhancement in specific heat capacity is due to addition of selected nano materials. doping molten salt with cnt and cuo nanoparticles results in enhanced specific heat capacity. � in conclusion, these results are noteworthy for csp technology. the increment in these thermo-physical properties can enable to the reduce cost of solar thermal power due to be operative at higher temperatures, hence higher thermodynamic efficiency, lesser material required with higher efficiency, therefore low material cost. refrences [ ] s. h. tajammul, m. s. adnan, m. siddiq, curr. nanosci., , , . 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[ ] x. zhang, h. gu, m. fujii, int. j. thermophy., , , . apr _iumrs:mrs.qxd international union of materials research societies mrs bulletin • volume • april • www.mrs.org/bulletin many exciting materials conferences are being planned in and beyond by the international union of materials research societies or its adhering bodies. and many of these conferences are collaborative efforts across the various adhering bodies. the european materials research society (e-mrs) will hold its spring meeting in strasbourg, france, on june – . the conference chairs are a. jaeger-waldau (european commission), h. meixner (max planck institute), j.r. morante (university of barcelona), and m. stuke (max planck institute). the meeting includes technical sessions on materials for energy, materials issues for oxide electronics, semiconductor materials, biomaterials, advanced func- tional materials, and diagnostics. work - shops will feature carbon dioxide as a new material for energy storage; the challenges for materials research in photovoltaic technologies, which is seen as a euro- pean strength; and the strand in the european commission’s program known as com plexeit [european institutes of tech nology] that focuses on nanotechnol- ogy for energy applications. to register for the meeting, e-mail to emrs@ emrs-strasbourg.com. the e-mrs fall meeting will be held in warsaw, poland on september – . the abstract deadline is may , . details on symposium topics and abstract submission can be accessed at web site e-mrs.org/meetings/fall . e-mrs is also accepting symposium topic proposals for the e-mrs iumrs inter - national conference on advanced mate - rials which will be held in ; the deadline is november , . see the e-mrs web site for details at www. emrs-strasbourg.com. mrs-singapore is the host this year of the iumrs international conference in asia (ica). ica is being combined with mrs-singapore’s international conference on materials for advanced technologies (icmat) on june 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these meetings have been organized annually and will provide an interactive forum for discussing numerous topics including advances in synthesis, characterization, properties, processing, applications, basic research trends, and corrosion prevention, all related to the area of materials science and engineering. the program includes a women in science luncheon. the efforts of several societies, colleagues, sponsors, and exhibitors allow a multidisciplinary forum that provides a valuable opportunity for research scientists to learn about new directions in materials research and tech- nology, as well as to share and exchange ideas with some of the best experts in the field. this is the first year that the materials research society is holding joint symposia with mrs-mexico, including topics on energy, water purification, and ion beams and nanomaterials. mrs and mrs-mexico are also holding an energy forum. registration at reduced rates is available until july . more information can be accessed at www.mrs-mexico.org. mx/webimrc . the iumrs th international con - ference on advanced materials (icam) will be held on september – , , in rio de janeiro, brazil. the conference is hosted by mrs-brazil, and chaired by guillermo solórzano (pontifícia univer - sidade católica do rio de janeiro). sym - posium topics include nanoscience and nanotechnology, health and biological materials, energy and environment, func- tional and electronic materials, structural materials, theory and phenomena, mate - rials education, and advances in engineer- ing mate rials. an e-mrs innovation workshop will be held, as well as a work- shop on the global nanotechnology workshop. the conference will also feature an iumrs energy forum. registration at reduced rates is available until july . more information can be accessed at www.icam .com. the second world materials summit on advanced materials for energy appli - cations and sustainable world develop - ment, a collaborative effort by the chinese 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co-chairs are boyun huang, president of c-mrs, and paul siffert, general secretary of e-mrs. more information can be obtained from the iumrs web site. the first announcement has also been issued on the first international con fer - ence on materials for energy to be held on july – , in karlsruhe, germany. this is a separate energy conference from the summit being held this year in china. co-sponsors of the karlsruhe’s conference include e-mrs and mrs. the program will cover current topics and recent progress in the science and technology of energy and new materials, including the nanoscale origin of macroscopic proper- ties. in detail, all aspects of materials for energy production and conversion, energy storage, energy transport, and energy sav- ing will be addressed. further information can be obtained from web site http: //events.dechema.de or by e-mailing to tagungen@dechema.de. upcoming conferences sponsored by iumrs or adhering bodies involve intersocietal collaborations www.iumrs.org https://www.cambridge.org/core/terms. https://doi.org/ . /mrs . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /mrs . https://www.cambridge.org/core journal of law, policy and globalization www.iiste.org issn - (paper) issn - (online) vol. , implications of global financial crisis on textile industry of pakistan sumra latif mughal shaheed zulfikar ali bhutto institute of science and technology (szabist mehrunissa chaudhary ms scholar at uet lahore abstract the global financial crisis of , had very little or no impact on our textile sector performance, the main cause of downward trend of pakistan textile industry is the reason of energy shortages, law and order situation, lack of active marketing strategies, and the behavior or small, medium and large manufacturers of textile products are more profit oriented, ignoring their responsibility towards social and economic development of pakistan. the author purpose was to explore the phenomenon of financial crisis and the performance of pakistan industry how they are linked and what factors were linked with both the crisis. the phenomenon studied includes the era of financial crisis and simultaneously the crisis of textile industry of pakistan and to identify the weak links. this study also aims to analyze the potential of productivity and investment of textile sector and its contribution in the earnings for the government of pakistan. the research participants were from the area of field research on textile sector of pakistan, working on it since last to years. data analysis was done by using colaizzi’s ( ) phenomenological methods; was used for data analysis, validation and verification. out of various statements themes emerged which represents the whole story how the textile sector crisis took place and the factors behind them. key words: financial crisis, textile sector, raw cotton, phenomenological study introduction: the global financial crisis started on october , which created two perceptions on its likely impact on the developing asian countries; on one hand it was perceived that developing asia, particularly china and some other countries, are now decoupled with the developed countries and would emerge as an alternative growth poles. the other school of thought believed that because of globalization, this region has more dependence on trade and investment and mainly on exports; it was likely that this region would be highly affected by the crisis. however a mix outcome has been witnessed by the world, it does not resulted in decline of gdp but the growth of these countries have slowed (chhibber j, ghosh j, palanivel t ). the impact of financial crisis is not similar in all countries around the world, depending upon the level of difference between reliance on exports and positions within globalization. the ‘inner critical core’ (green d, king r, dawkins m ) countries namely china, vietnam and indonesia – has consolidated its production of textiles and garments into a pool of strategic suppliers’. the customers mainly rely for the most important share of their production, during ‘bad times’ their orders may fall but their market share remain intact, in contrast to second line suppliers e.g. india, pakistan, and sri lanka nad marginal suppliers like caribbean basin and cambodia, which experience drops in both order and market share (green d, king r, dawkins m ). the textile and garments industry is one of the most globalized sectors of the world providing employment opportunities to more than million people around the world (forstater m ). textile industry of pakistan contributes almost % (usd . billion) to the countries total exports and % to the total output i.e. . % to the country’s gdp. among asian countries pakistan is the th largest producer of textile products and contributing % to the total employment of the country, but its contribution in the international textile market is very marginal as compare to the neighboring countries. china, india, bangladesh, vietnam and indonesia are highly mechanized and equipped with technology to produce high quality, low priced textile products and increased supply in international market (tahir m, mughal k ). the global financial crisis affected these countries minimally but its impact on pakistan is more severe, contributing to the decline of textile industry other factors included law and order situation, electricity and gas shortages, inflation, political instability and stock exchange volatility etc. all resulted in movement of our industry to bangladesh and other countries. the main aim of this study is to identify how factors associated with financial crisis impacting the textile industry of pakistan, mainly from the point of view of experts who are religiously following the pre and post crisis period. the purpose of this study is to discover and know the situation of textile sector of pakistan through obtaining the information from key participants in their respective area of knowledge and understanding of the phenomena under study. what they had experienced during the crisis and how they reacted to the situation, what steps they have been taking in order to improve the textile sectors performance. the experiences of people from the textile sector during the crucial period will allow us to have insights of the actual situation which prevailed at that point of time. journal of law, policy and globalization www.iiste.org issn - (paper) issn - (online) vol. , the main aim of this study is to identify how factors associated with global financial crisis of had an impact on the textile sector of pakistan. the phenomena that will be studied will include the era of financial crisis and simultaneously the crisis of textile industry of pakistan and to identify the weak links. this study also aims to analyze the potential of productivity and investment of textile sector and its contribution in the earnings for the government of pakistan. literature review: pakistan is the th largest producer of textile products and th largest producer of cotton in asia, competing with china, india and bangladesh as major rivals in the international market. the financial crisis of has also affected the developing asia (green d, king r, dawkins m ), the inner circle including countries like china, vietnam and indonesia which were directly exporting value added products to united states and eu were more severely affected than those of outer circle countries namely, pakistan, india and bangladesh. pakistan is the major exporter of raw material to the regional textile producing countries namely china, india and bangladesh, therefore the impact of financial crisis is not severe in pakistan as compare to those countries who are direct exporters of finished goods to the countries where the bubble burst. textile sector of pakistan is assumed to be the backbone of the economy, its contribution in the gdp is . %, employing almost % of the country’s population of around million people. $ trillion is the annual volume of total world textile trade, which is growing at the rate of . % per year, but contribution of pakistan is less than % which is usd . billion a major source of foreign exchange earnings for the country. the empirical research plays a very important role in this area of study bhalhotra ( , cited in alam ) was the first who investigated the impact of ’s world financial crisis. bhalhotra ( ) empirically determined the significant positive effects of capital stock, previous period’s employment and output change, and negative effects of man-hours and previous period wages on the employment. alam ( ), in his research paper concluded that the financial crisis along with many other factors gave rise to the decline of textile industry of pakistan including; energy crisis, disclosure by textile mills owner, secrecy of information due to tax avoidance all led to the crisis of textile industry. pimple ( ) in his study on global financial crisis concluded that, “we must be bold than ever in these times of crisis, when we are tempted to look inward, it is precisely the time when we must move pursuit of the common good to the top of the agenda. while recently we have heard much in the us about how problems on wall street are affecting innocent people on main street, we need to think more about those people around the world with no streets”. gec in its study identified two major factors that were hardly hit by the financial crisis; first the developing countries which were having most globally integrated financial sectors next came the impact on trade, as volumes and prices of commodities and manufactures collapsed across the globe. the report also concluded that, “the financial crisis of has had terrible results in rural areas, firstly unemployment has risen higher and higher as compare to previous crisis, secondly, salaries of people have either dropped or remained same and thirdly, salaries are not available on time to employees as companies are also facing hard time to release cash to employees and they cannot even afford to pay them. the impact of this crisis has been witnessed in healthcare sector as well: for example, one community member who is in need of surgery has had to postpone it because last month her husband’s salary didn’t arrive. and it is usually the women who are postponing treatment because of the impact of the crisis on household finances. many women in our community healthcare scheme who have recently undergone mammography screening and been recommended to have surgery now cannot afford to pay for it – this is mostly because of the crisis.” the research on this topic has been very limited and this creates a scarce of literature available on this topic. other than financial turmoil the political and socio-economic condition of the country is also not favorable this resulted in the continuous bad performance of textile sector although the government subsidies are more as compare to other sectors. latif et al ( ) in their study showed that the financial crisis is negatively impacting on the trade growth; the exports fell mainly because of a drop in world trade prices. this has also resulted in import of vegetables by the government and now they are working on policy level to smooth out the effect of crisis. pakistan textile sector and its performance: pakistan’s textile industry comprises of large scale organized and highly fragmented cottage/medium and small units including; raw cotton, ginning, spinning, knitting, printing and dyeing & apparels and made ups, these all small industries contribute to make up the overall textile sector. the macro-economic indicators of pakistan economy shows downward trend since , the pattern as followed by decline in foreign aid, foreign direct investments, and diminishing growth in exports, although there was upward trend of remittances to pakistan but solely this factor could not contribute for the losses generated by other macro-economic factors. journal of law, policy and globalization www.iiste.org issn - (paper) issn - (online) vol. , the economic survey of reported that the gdp growth of the country reported declining trend since , exports to gdp ratio also declined, foreign official aid and foreign direct investment also showed negative growth whereas remittances improved and increased. as alam discussed in his report that the macro- economic variables of pakistan economy are not much hit by the crisis due to low integration of our economy in financial sector. the other factors that were identified in his report included; power deficit in pakistan, lack of foreign investors, risk awareness together with global financial crisis led to the fall in foreign direct investments. it is therefore concluded in his research that the global financial crisis along with other factors were responsible for the downward trend of textile sector. now the textile sectors has started performing well and the movement of industries to bangladesh has led the investor to produce textile products with low cost of production. research methodology: sample: purposive sampling techniques is used for the research study, only relevant personnel from the research area on textile sector are contacted and interviewed in order to get the rich information snowball sampling technique is also used to reach the research participants they were contacted with reference of other people. for this research study interviews were planned to be conducted but due to short of time and unavailability of the participant in pakistan i was restricted to conduct only interviews. as this is a phenomenology study interviews were done to get the maximum information for our study from the personnel who are working as a research analyst on textile sector of pakistan as they are aware of the trends and impact of financial crisis on the textile industry. research design: the research design that is most suited for this research is phenomenological research design, as the researcher’s main objective is to provide the readers with lived experiences of the experts from the textile industry of pakistan during the difficult phase of global financial crisis. in a phenomenology study the researcher transcends or suspects the past knowledge and experience to understand a phenomenon at a deeper level merleau ponty, ( ).exploring the researchers view on textile sector how they look at the crisis and what structural changes they pose in reflection of their work that they were doing during the last – years. phenomenological methods are particularly effective at bringing to the fore the experiences and perceptions of individuals from their own perspectives, and therefore at challenging structural or normative assumptions lester, ( ). procedure: after the approval and availability from the interviewees the interviews were conducted one person was from the state bank of pakistan working in economic policy review department as assistant director since last years, he was working on external sector and had a good knowledge about the textile sector of pakistan and the global financial crisis. the other interview was conducted online because of unavailability of the interviewer in karachi; he is mr. rao muhammad tariq jahangir, business relations officer at iqbal silk mills, his views were also taken for the data collection purpose. one interview was tape recorded and the other was online both were transcribed verbatim. participants are established persons in their field and were having useful and rich information on the topic which were posed to them. they cooperated with us even after the interview so that i journal of law, policy and globalization www.iiste.org issn - (paper) issn - (online) vol. , may go back to them and check if the interviews were transcribed properly or not. whatever i have written was in accordance with what they meant or should i need to make some changes in analysis part. after informed consent taken from participants they were asked to respond on what they knew about the global financial crisis and the textile sector of pakistan, how they see the whole phenomenon and what measure they pose for improvement of performance of our textile industry. background information of participants was obtained through the references with the help of whom we reached to our actual research participants. data analysis: data collection and analysis in qualitative research are done simultaneously, for this research study researcher i have used colaizzi’s phenomenological method, to analyze the phenomena and exclude researchers’ biases from the research (groenewald, t ). after reading the transcripts various times to have the gist of the whole idea, from each transcript, important phrases and sentences are extracted that most nearly explains the phenomena of crisis in textile sector of pakistan. the formulated meanings are then divided into themes allowing for the emergence of actual factors that were discussed by both the interviewers. the results are then combined together to develop an in depth and exhaustive description of the phenomenon. once the data is clustered in themes the research went back to the actual participants to validate the findings, if the data emerged is relevant it is included in the final description and other irrelevant data was excluded from our final report. a mix of data analysis tools are used including ipa and narrative analysis in order to provide the readers with complete description in the form of narrations of the interviewers and how they make sense out of their experiences are captured and recorded. reliability and validity: methodological severity was attained through the application of verification, validation and validity meadows & morse, ( ). data reliability and validity in qualitative research is very difficult to identify, for this research study i have used triangulation technique to validate the data collected and analyzed, another way to validate the data is to get back to the participant and discuss again whatever i have analyzed whether the results generated are the same as the participant narrated during the interview or he meant something else and the researcher understood something else. in order to maintain the credibility and trustworthiness of the research the sources from where the data has been collected and the persons interviewed their complete details are provided in the appendices and the transcription of the interviews are also shared. various sources of data collection have been used to triangulate and validate the results and the findings are in line with the research objective. results: for the data analysis we have used the transcription following noteworthy statements were extracted, significant statements with their formulated meanings are written in table , while arranging these meanings into clusters themes emerged from data. table contains the theme clusters that emerged from their associated meanings in connection with the research questions and objectives of the research. table : some examples of important statements and their meanings in context of global financial crisis and textile sector os pakistan statements formulated meanings as in pakistan, main hub of textile industry is in faisalabad, which was badly effected during last winter season because of shortage of gas. as a buyer we have to pay full payment in advance for the delivery and the quantity we order wouldn’t be fulfilled, quality is sacrificed and time also. some of them shifted to abroad because of bribe demand, one more thing is, some business man shifted to rural areas of karachi the financial crisis did impact the textile sector but the impact was not very severe if we compare it with other countries, the point is that pakistan exports low value added products like raw cotton, cotton yarn and cotton fiber these are low value added products. whatever the demand is these kind of products raw cotton, cotton yarn there demand will always be there, the point is that textile exports did slow down but not very significant as large scale manufacturers have there own powerplants to electricity generation. energy shortage is one of the main cause of crisis of textile sector in pakistan, mill owners are unable to complete the project on time and could not deliver the finished goods on time as well small and medium manufacturers move to bangladesh for low cost of production facility and high profit margins as pakistan is low value products making company therefore the financial crisis impact on it is very low as compare to high value products making countries the demand for low value products i.e. raw cotton, cotton yarn and cotton fiber will always remain there as high value products making countries will require them. the manufacturers e.g., gul ahmed, al karam and nishat they have their own power plants therefore they faced little or no disturbance from energy crisis. it was difficult for small and medium manufacturers to survive in energy shortages so they decided to move as they were producing gloves sox etc so their market journal of law, policy and globalization www.iiste.org issn - (paper) issn - (online) vol. , the medium and small size manufacturers who are operating in two rooms’ factory producing gloves sox etc export they have their markets and faced an impact on main exports. so the decided to switch to bangladesh took their unit their and collaborated with local manufactures. two aspects are there first the shortage of electricity and cost of production in bangladesh is very low and nd is that bangladesh enjoys additional benefits from eu generalized store preference, also available to pakistan but bangladesh can export in extra quantum, so if an investor wants to exports finished goods he can export more from bangladesh and in good rates gloves from gloves can be exported the other major reason is that india does not want to export directly in pakistan, so they could invest in bangladesh company and avoid political pressure as well. the third aspect is that china, india and bangladesh is our major competitors in raw cotton, but production of raw cotton is better than these countries, this is our competitive advantages as well and we export raw cotton to china and bangladesh so our mill owners decided that if we are exporting raw cotton to bangladesh it is much better we should move there and export high value product to worldwide. was getting disturbed. one major reason for shifting of factories to bangladesh is that cost of production is low there and the mill owners does not have to setup an additional plant their and maintain the facility but they work in partnership with ocal manufacturers and share their factory premises for their production of finished goods and are earning ample profits. bangladesh enjoys additional benefits from us and eu in terms of exports they are allowed to export in more quantities as compare to other companies so our investors are enjoying that benefit also indian investors are not allowed to make their investments directly in pakistan, so by moving to bangladesh indian investors can also invest in our companies and help us in earning foreign exchange in ample quantities one major benefit that we enjoy is that the production of cotton is more than our requirements so we can export raw cotton in more quantity to bangladesh and increased our production of finished goods and enter the international market via bangladesh. table : example of cluster themes with their formulated meanings: manufacturer or low value products: • exporter of raw cotton, cotton yarn and cotton fiber • exporting raw cotton to our competitor countries • low cost benefit in bangladesh • lack of technical facilities domestic issues: • energy crisis • law and order situation of the country • internal instability • reluctance of foreign investors • small and medium investors movement to bangladesh • unable to complete assignments on time theme : manufacturer of low value products: journal of law, policy and globalization www.iiste.org issn - (paper) issn - (online) vol. , the financial crisis of did impact the pakistan textile sector but its impact was very low as compare with other countries, pakistan’s major exports are from low value added products like raw cotton, cotton yarn and cotton fiber. the high value products are readymade garments, bed ware, towels which we do not export to usa and eu in high quantity. when the global financial crisis was on its peak pakistan exports bit slow down but its impact was not severe, as whatever the demand is these kind of products raw cotton, cotton yarn and cotton fiber there demand will always remain same, our textile did slow down but not very significantly. as compare with china, india and bangladesh because they export high value products like readymade garments, jackets, denim etc. products, so this was the main thing that it did impact and our exports went down. but financial crisis was an important factor which led to the overall slowdown but this was not the only factor domestic factors are also there. if we start producing high value products and export them directly to us and eu then our market will be expanded but currently we are supplying raw cotton to our competitors only. theme : movement of small and medium manufacturers: small and medium manufacturers are the one which were most affected by the textile sector bad performance, small manufacturers operate in a two room factory, manufacturing gloves and sox etc they have their own market for exports, they were highly affected when the financial crisis took place and simultaneously the energy crisis. energy shortages were the main cause that they decided to move to bangladesh as they were unable to complete consignments on time and lost their potential customers. the investors also preferred to give projects to a country where internal stability and energy crisis are not there and they expect the consignment to reach them on time. therefore the small and medium manufacturers shifted their setup to bangladesh so that they may have low cost of production and complete their work on time. these manufacturers in collaboration with local textile investors signed deal to use their premises for work and share the profit. theme : increased profits: the movement of small and medium manufacturers led them to work efficiently and have higher returns on their investment abroad. bangladesh is a good place to work for these investors they face less legal proceedings there and have benefit of producing at low cost without heavy investment of installation of plant and machinery and its maintenance, they simply share the factory of local manufacturer and export them raw cotton and earn huge margins of profit and sent them back to pakistan. another aspect of this is that the indian investors were not allowed to make their investments directly in pakistan so they also have the benefit to make their investment in pakistani company while staying in bangladesh without any political pressure. the other major benefit of working in bangladesh is that they enjoy additional benefits from us and eu generalized store preference, also available to pakistan but bangladesh can export in extra quantum, so if an investor wants to exports finished goods he can export more from bangladesh and in good rates gloves from gloves can be exported. in this way more exports of finished goods are possible for the manufacturers of pakistan as well. theme : ample production of raw cotton: pakistan’s fertile land is very favorable for the production of cotton, our yearly production is more than our requirement therefore it becomes easy for us to export raw cotton. before the textile industry crisis, if the production of cotton was bales we used to export bales and the remaining bales were used internally for the production of high value products and the demand of local citizens were met. but now if the production is bales we export bales and use bales to cater internal demand currently we are not exporting any high value products in international market. other dynamics for china, india, bangladesh and pakistan are same but one additional benefit we ought is the excess production of raw cotton. pakistan is now exporting raw cotton to regional countries who are our close competitor also and they purchase cotton in low prices from us and refine them and produce high value products and export to us and eu. theme : energy crisis: the major reason for the textile industry crisis is the energy shortages throughout the country our entire textile mills are closed in faisalabad due to no electricity. there are two issues in this, first that large scale textile mills does not faced any problem in energy crisis but the impact was on low scale manufacturers as large scale manufacturers have there own powerplants for electricity generation. the medium and small size manufacturers who are operating in two rooms’ factory producing gloves and sox etc. export they have their markets and faced an impact on main exports. so the decided to switch to bangladesh took their unit their and collaborated with local manufactures. the problem of energy crisis started in when global financial crisis was at its peak and now when the financial crisis in us and eu has slow down the energy crisis in pakistan is at its peak, therefore we cannot say that the major reason for the downward trend of our textile industry is due to the global financial crisis. theme : internal instability: pakistan is facing internal instability during the last few years, terrorist activities are all time high, law and order situation is also not good, call for strike and lockout may take place anytime. uncertainty is everywhere no one is sure of their life, in such a turmoil situation foreign investors are also reluctant to come to pakistan and make journal of law, policy and globalization www.iiste.org issn - (paper) issn - (online) vol. , their investments here because they believe if they come here and before reaching to faisalabad, to see their production status, they will be killed in a bomb blast or something will happen to them. the other problems include unemployment increased, in faisalabad where the workers earlier work in double shifts are now working in single shift because there is no electricity available for them to work. shortage of energy is one of the most significant problems which everyone in our country is facing. first we need to improve our internal problems and show to world a soft image of pakistan so that new investors may come in and make their investments in pakistan. theme : activities of large manufacturers: the large manufactures are producing their own electricity from power plants they have installed at their premises they would not allow small and medium investors to share their electricity. either the geographical boundaries will come in between i.e. a factories at chenab will not be able to share electricity with a power plant in sind. small investor will not be allowed to work in the factory premises of the large manufacturers as they will copy their prints, design and technology. therefore small and medium manufacturers are moving to bangladesh because they are having low cost of production and cheap labor. the large manufacturers for example gul ahmed, nishat mills, al-karam has shifted their concentration from exporting finished products to serving needs of local market, as designers lawn prints are more in fashion these days so they are earning good profits from their domestic market only. a small share of unstitched suits are exported to india informally through participating in trade exhibitions, seminars and fashion shows, whereas they are not involved in direct exports to india and other countries. the revenue earned from this activity is not part of exports of our country but are included in services industry revenue. scope and marketing activities are very active for these companies but for the time being their primary focus is domestic market however there is immense demand for our lawn products in international market. the prices of the local manufacturers are high due to competition, the consciousness among customers about fashion trends, even fashion models have started to launch their own lawn prints. the market to which they are catering is very limited and high class, so they can afford to pay for such high prices; these companies are getting good profits from their domestic market only. the focus of this trend is in urban areas only their market is very limited and the people are ready to purchase these products at high prices as well. theme : movement of labor: unemployment has increased in pakistan, as our labor is unemployed, earlier they were working in double shifts now single shift is hardly available. this is the reason why our labor is moving to middle east and bangladesh, for the work. as they believe that there are work opportunities for them and they can earn good and sent money back to their families. in order to retain our skilled labor we need to improve the performance of our textile sector by creating a conducive environment for work, improved law and order situation, reduced energy shortages etc. theme : outsourcing textile segment: outsource activities which us and eu used to do in recent times was very limited in our market, and now that segment is also facing energy shortages this is why their work is disturbed and this segment is highly affected by the financial crisis, overall in our textile sector the contribution of this segment is very low i.e. to % only therefore the disturbance in this segment does not contribute much in the crisis of our textile sector. simultaneously the cotton prices went up and the export proceeds from raw cotton led us to cover the loss which we suffered in outsource activities segment. theme : reluctance of foreign investors: one of the major drawback of our country is that the perception of pakistan is not good in the eyes of the world, foreign investors believe that if they will come to pakistan they will be killed in a terrorist activity, therefore they also prefer moving to bangladesh, india and china because they found economic, political and social stability in these countries. the world economic forum report states that pakistan is the nd worst country in terms of stability, after reading such reports who will come to pakistan for investment. we need to improve our image by marketing soft image of pakistan to the world. theme : marketing strategies of our textile companies: in order to improve our textile sector performance we need to focus on marketing strategies for the textile i.e. participation in trade exhibitions, seminars, fashion shows etc. all around the world so that a soft image of pakistan may appear in front of them as our competitor countries are doing. textile sector must focus on introducing their brands in international market and increase marketing activities. explore new markets like south africa, middle east and other countries where we find potential customers so that our export of finished goods may increase and help us in gaining more profits and export receipts. theme : other domestic issues: other than energy crisis there are various other domestic issues which we must cater to improve our performance of textile sector i.e. law and order situation of the country, political stability, corporate governance practices of textile sector companies and the regulatory bodies, accountability of manufacturers and investors journal of law, policy and globalization www.iiste.org issn - (paper) issn - (online) vol. , and the improvements in the structural flaws of the textile sector. if we cater the domestic issues first then ultimately our performance would improve in front of the whole world and our textile industry would be recognized among them. discussion: in this study, implications of global financial crisis on textile sector of pakistan, the reasons which were identified other than financial crisis are energy shortages, law and order situation of the country, internal instability, interests of small and medium manufacturers, all these factor led to the development of crisis of our textile sector. the practice of exporting raw cotton to our competitor countries has allowed pakistan to reduce its production of finished goods to cater the demand of domestic customers only where as if we export raw cotton in less quantity we can increase the production of finished goods and earn export proceeds from us, eu and other african and middle east countries. this is one of the major structural flaws in the textile industry of pakistan. the bodies which are working for the textile companies include; pakistan textile exporters association (ptea), all pakistan textile mills association (aptma), and ministry of textile all together needs to make some structural changes in textile sector in order to improve its efficiency and effectiveness. the one major drawback of pakistan textile industry is that we export low value products to our competitor countries in good rates and they refine the cotton and produce high value products and earn far more income from exports, this structural flaw can be mitigated by reducing the exports of raw cotton and increased export of high value or finished goods. along with this marketing strategy should also be improved so that we can market soft image of pakistan by sharing our culture and attitude in the international market and once again we’ll be able to increase our exports in international market. all this can be done once energy crisis problem is resolved the major concern for manufacturers today is the shortage of energy, textile mills rather than moving to bangladesh, they together with the help of government of pakistan, can make a one time investment of power plant which can produce electricity for the mills only in this way our industry will remain in our country and the production efficiency would improve. in order to attract foreign investors to pakistan, the government should stabilize the law and order situation so that the life of every citizen is secured and the foreign investors would come to pakistan with confidence. if fdi will come to pakistan we will be able to export directly to us, eu and other parts of the world and earn more revenue from exports rather than from remittances or in any other form. the textile sector of pakistan has every potential to work efficiently but this short term energy crisis has disturbed our performance. the investors who have already moved to bangladesh are not likely to return in to years because they have made their investments there and even they have not yet achieved their break even, so they must continue working there and simultaneously earning from there they must invest in pakistan so that one source of investment in textile sector will be from there contribution it will help us in stabilizing and improving the overall performance of the textile industry of pakistan. the link of crisis of pakistan textile industry and global financial crisis is very thin, beacsue when the financial crisis was at its peak in the textile sector performance was hardly affcetd and now when the financial crisis has been slow down our textile sector performance has worsen. therefore we conclude that there is not direct link between textile sector of pakistan and the global financial crisis however unlike other countries of the world in some sectors we have also faced some recursions of crisis but there is no direct link found in the financial crisis and textile sector crisis of pakistan. references: abbas et al , “impact of financial crisis on textile industry in pakistan”, information management and business review, vol. , no. , pp. - ahmed a, , “growth trends of pakistan textile industry”, < http://www.rcci.org.pk/wp- content/uploads/ / /gtopti.pdf> ahmed, y, , “textile industry of pakistan”, horizon securities alam i, , impact of financial crisis on textile industry of pakistan: evidence from faisalabad, south asia network of economic research institutes, no. - chhibber, j, ghosh, j, palanivel, t , “the global financial crisis and the asia-pacific region, a synthesis study incorporating evidence from country case studies” forstater, m , “implications of the global financial and economic crisis on the textile and clothing sector”, international labour organization, sectoral activities programme green, d, king, r, dawkins, m , “the global economic crisis and developing countries: impact and response”, oxfam research report groenewald, t , “a phenomenological research design illustrated’, international journal of qualitative methods, vol. no. . article viewed february , from <http://www.ualberta.ca/~iiqm/backissues/ _ /pdf/groenewald.pdf> iqbal et al, , “development of textile industrial clusters in pakistan”, asian social science, vol. , no. journal of law, policy and globalization www.iiste.org issn - (paper) issn - (online) vol. , memon, a , “pakistan ranks as one of the major woven fabrics suppliers”, viewed february , : <http://www.ptj.com.pk/web- / - /weaving-drnoor-ahmed.htm> pacra , “textile sector study”, the pakistan credit rating agency limited, < http://www.pacra.com.pk/pages/research/archive/sector_study/textile/study/textile_ss_dec_ .pdf> tahir, m, mughal, k , “pakistan textile industry and the neighbouring countries (a globalization effect)”, far east journal of psychology and business, vol. , no. , pp - usmani f, , “textile industry of pakistan”, viewed february , http://www.utrade.co/magazine/utrade-magazine.aspx?key= &title=textile+industry+of+pakistan pakistan textile export association, viewed on april , , < http://www.ptea.org.pk/> ministry of textile, viewed on april , < http://www.textile.gov.pk/gop/index.php?q=ahr cdovlze mi xnjgunzaumtm l vdgkv> all pakistan textile mill association, viewd on march , , < http://www.aptpma.com/> pakistan textile journal, viewed on march , <http://www.ptj.com.pk/> the iiste is a pioneer in the open-access hosting service and academic event management. the aim of the firm is accelerating global knowledge sharing. more information about the firm can be found on the homepage: http://www.iiste.org call for journal papers there are more than peer-reviewed academic journals hosted under the hosting platform. prospective authors of journals can find the submission instruction on the following page: http://www.iiste.org/journals/ all the journals articles are available online to the readers all over the world without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself. paper version of the journals is also available upon request of readers and authors. more resources book publication information: http://www.iiste.org/book/ iiste knowledge sharing partners ebsco, index copernicus, ulrich's periodicals directory, journaltocs, pkp open archives harvester, bielefeld academic search engine, elektronische zeitschriftenbibliothek ezb, open j-gate, oclc worldcat, universe digtial library , newjour, google scholar http://www.iiste.org/ http://www.iiste.org/journals/ http://www.iiste.org/book/ silicon photonics for telecommunications and biomedicine samia a. suliman silicon photonics for telecommunications and biomedicine samia a. suliman silicon photonics for telecommunications and biomedicine samia a. suliman silicon photonics for telecommunications and biomedicine samia a. suliman silicon photonics for telecommunications and biomedicine samia a. suliman silicon photonics for telecommunications and biomedicine samia a. suliman downloaded from: https://www.spiedigitallibrary.org/journals/journal-of-nanophotonics on apr terms of use: https://www.spiedigitallibrary.org/terms-of-use silicon photonics for telecommunications and biomedicine sasan fathpour and sasan fathpour, eds., xiii+ pages, isbn - - - - , crc press, boca raton, florida ( ), us $ . , hardcover. reviewed by samia a. suliman, pennsylvania state university, department of engineering science and mechanics, university park, pennsylvania the silicon metal-oxide-semiconductor field-effect transistor (mosfet) is the basic unit of digital technology that has altered the shape, form, pace, and the very nature of human interactions on planet earth. silicon is one of the most studied materials in the history of man, the other two being steel and cement. the study of silicon is unique and today % of photo- voltaic cells are silicon-based. in addition to its excellent electronic semiconducting properties, silicon’s mechanical pro- perties render it a basic element for micro-electro-mechanical systems (mems). the silicon mosfet’s successful and continuous miniatur- ization in the last six decades is today confronted with numer- ous challenges that can be summarized into three facets: the quantum-mechanical limits imposed on the principle of device operation, power dissipation, and the exponentially increasing cost of setting up new semiconductor fabrication plants. the last of the three is affectionately termed moore’s second law. industry focus is now shifting from the vertical pursuit of further miniaturization to the hor- izontal enhancement of functionality of the technology in other arenas. for example, a field of application that has benefited from this aggressive lateral shift of industry is power electronics. twenty percent of the global electricity consumption is in lighting, while % of the energy is consumed worldwide in handheld electronics. the recent focus on silicon photonics and its applications promises tremendous possibilities for the solution of the impending energy crisis. in their comprehensive compilation of research activities in utilizing silicon in a new arena, sasan fathpour and bahram jalali have opened my eyes to silicon-photonics applications in telecommunications. the conjunction of solid-state physics, electrical engineering, and material science has given birth to spectacular digital technology and taught humanity a valuable lesson of the tremendous value of multidisciplinary work. it astonished me that the microelectronically rudimentary structure of intrinsic silicon coupled with a metal can be utilized as a basic unit of silicon plasmonics, namely, a waveguide. in line with bandgap engineering we now have density-of-carriers engineering. the advantage of integrating silicon photonics with electronics is the low cost associated with complex optics functionality. optical pathways consume less energy in comparison to metallic interconnects. as a result, photonics provides a solution to the power dissipation issue while performing inter- and intrachip information transfer at the speed of light. the milestones for the potential of silicon-photonics integration are the realization of micrometer-scale waveguides, modulation of the free-carrier density, strained germanium on silicon layers for infrared detectors, and commercial emergence of silicon-on-insulator as a - / /$ . © spie book review journal of nanophotonics - vol. , downloaded from: https://www.spiedigitallibrary.org/journals/journal-of-nanophotonics on apr terms of use: https://www.spiedigitallibrary.org/terms-of-use platform for optical confinement layers, coupled with inherent advantages of silicon as an element. the first chapter of the book deals with the evolution of silicon photonics since its inception in the mid- s. during the s the focus was on the waveguides. silicon optical modulators as transceivers rely on carrier injection, accumulation, and depletion for changing the refractive index in a waveguide as the basic telecommunication component. the research trends are for smaller waveguides to reduce power consumption and real estate. in addition, the chapter dis- cusses key technological challenges: light sources, power consumption, couplers, packaging, and fiber alignments, not to mention size differences in photonics and electronics relevant to plasmonic waveguides. silicon plasmonics as the newcomer to plasmonic literature is the subject of the second chap- ter. silicon-plasmonic waveguides have been built and tested. the structure is simple consisting of layers of conductors and dielectrics. the possibility of integrating plasmonics with electronics and with photonics for potential plasma-opto-electronic integrated circuits (poeic) is discussed. the importance of stress engineering in altering the linear and nonlinear optical properties of silicon is discussed in chap. . in particular, dynamic tuning of a silicon waveguide’s bire- fringence is achieved by integrating a piezoelectic transducer (pzt). the second case of stress engineering studied is the periodically poled silicon (pepsi) photonic device. chapter covers the physics of the nonlinear optical effect of two-photon absorption (tpa), which is particularly strong in semiconductors. tpa and tpa-induced free-carrier absorption (fca) and their roles in pulse-shaping mechanisms are discussed. fca is reduced either by ion implantation or by using the p-i-n structure to reduce carrier lifetime. the theory of silicon raman amplifiers and lasers is the topic of chap. coupled with an extensive list of references. chapter is focused on the biomedical applications of silicon photonics. the role of silicon as a photonic material in the technologically important midinfrared regime and its interaction with biological materials is discussed in chap. . the growth of iii–v material on silicon is covered in chap. . chapter discusses the hybrid silicon group iii–v lasing applications. the -d integration of cmos with photonics is the subject of chap. . the subject of nonlinear photonics and energy harvesting is tackled in chap. . the book concludes with chap. on computer-aided designs for cmos photonics. with the amalgamation of the state of the art in silicon photonics work and its concise pre- sentation coupled with the provision of an extensive list of references, i highly recommend the book for all those embarking on graduate studies in the field and its related areas; in addition i highly recommend it for all r&d groups in the semiconductor industry. book review journal of nanophotonics - vol. , downloaded from: https://www.spiedigitallibrary.org/journals/journal-of-nanophotonics on apr terms of use: https://www.spiedigitallibrary.org/terms-of-use damage‐associated molecular patterns: their impact on the liver and beyond during acetaminophen overdose damage-associated molecular patterns: their impact on the liver and beyond during acetaminophen overdose see article on page a cetaminophen (apap) is one of the most commonly used drugs for treating pain and fever. although it is safe at therapeutic dosage levels, overdose of apap causes severe liver injury (apap- induced liver injury; aili), with the potential to progress to liver failure. up to % of patients who suffer from liver failure will die (or undergo liver transplant). data combined from specialty medical centers in the united states revealed that aili accounts for approxi- mately half of acute liver failure cases and results in more than , emergency room visits, , hospitaliza- tions, and an estimated deaths each year. apap hepatotoxicity is initiated by the generation of a chemically reactive metabolite (n-acetyl-p-benzo- quinone imine; napqi). napqi depletes liver gluta- thione and covalently binds to cellular proteins, thereby causing mitochondrial dysfunction. - studies using rodent models in the last four decades have demonstrated that mitochondrial disruption is the key underlying mechanism of aili (fig. fig )). cova- lent binding to mitrochondrial proteins by napqi causes oxidative stress and mitochondrial membrane permeability transition pore opening, which triggers the collapse of membrane potential, cessation of aden- osine triphosphate (atp) production, and the release of apoptosis-inducing factor and endonuclease g. - together, the mitochondrial dysfunction, energy crisis, and nuclear dna damage result in hepatocyte necrosis. in recent years, there has been a growing interest to investigate whether downstream events of early hepato- cyte necrosis contribute to the aggravation and pro- gression of aili. necrotic cells release a number of damage-associated molecular pattern (damp) mole- cules, such as high-mobility group box- , heat-shock proteins, hyaluronan, fibronectin, cardiolipin, and dna fragments. upon activation by damp mole- cules, innate immune cells infiltrate the damaged area and release cytokines and cheomokines, thereby caus- ing tissue sterile inflammation. - the soluble prod- ucts of innate immune cells can exacerbate tissue dam- age, as well as promote wound healing (fig. ). perhaps as a result of this dichotomy, the overall con- tribution of innate immune cells, such as neutrophils, to aili remains unclear. in this issue of hepatology, marques et al. report on a study demonstrating that damp molecules released from necrotic hepatocytes recruit and activate neutrophils in the liver, which, in turn, amplify aili. three experimental approaches were employed to elu- cidate the pathological role of neutrophils in aili. consistent with published reports, , the present study shows that neutrophil depletion by an anti-gr- antibody significantly attenuates aili. furthermore, the combined use of a cxc chemokine receptor an- tagonist and a formyl peptide receptor (fpr ) an- tagonist also blocks hepatic recruitment of neutrophils and mitigates aili. this approach is based on the investigators’ previous finding that an intravascular gra- dient of chemokines and mitochondria-derived formyl peptides collaboratively guide neutrophils to sites of liver necrosis. these two separate in vivo studies demonstrate that liver injury initiated by apap chal- lenge is amplified by infiltrating neutrophils. the investigators further examined the cytotoxic potential of neutrophils against hepatocytes. neutrophils isolated from healthy individuals were cocultured with apap- treated hepg cells. data show that the cytotoxicity of hepg cells is enhanced by neutrophils in a cell- contact–dependent manner, and that necrotic hepg cells significantly increase reactive oxygen species pro- duction by netrophils. collectively, these findings pro- vide evidence to support a pathological role of neutro- phils during aili. traumatic injury is known to cause ‘‘septic-like’’ sys- temic inflammatory response in the absence of infec- tion. the underlying mechanism is recently abbreviations: aili, apap-induced liver injury; apap, acetaminophen; atp, adenosine triphosphate; damp, damage-associated molecular pattern; fpr , formyl peptide receptor ; il, interleukin; mtdna, mitrochondrial dna; napqi, n-acetyl-p-benzoquinone imine; tlr- , toll-like receptor . address reprint requests to: cynthia ju, ph.d., school of pharmacy, university of colorado health sciences center, east th avenue, c , denver, co . e-mail: cynthia.ju@uchsc.edu; fax: - - . copyright vc by the american association for the study of liver diseases. view this article online at wileyonlinelibrary.com. doi . /hep. potential conflict of interest: nothing to report. elucidated by the detection of mitrochondrial dna (mtdna) and formyl peptides released in the serum of trauma patients. circulating mitochondrial damps activate neutrophils through toll-like receptor (tlr- ) and fpr , respectively, thereby eliciting neutrophil-mediated organ injury. because apap causes mitochrondria damage, it is likely that mito- chondrial contents are released into the circulation. evidence supporting this hypothesis is provided by a recent study detecting circulating mitochondrial bio- markers, including mtdna and glutamate dehydro- genase, in the serum of patients with aili. similarly, the present study shows a significant increase in serum mtdna levels in acute liver failure patients, compared to healthy volunteers. the elevation of circulating mtdna is also observed in apap-treated mice. the effect of mtdna release on aili is revealed by a sig- nificant decrease of liver injury in tlr- �/� mice, compared to wild-type mice. this finding is consistent with a published report of protection against aili by tlr- antagonists and in tlr- �/� mice. apap-induced liver failure is accompanied by other tissue complications, such as encephalopathy, coagul- opathy, renal failure, metabolic derangements, cardio- vascular compromises, and severe lung injury. , toxic effects on remote tissues may be the result of the original insult of apap, but, in many cases, are conse- quences of severe liver injury. a novel finding of the present study is the observation of marked lung injury in mice treated with apap. data suggest that lung injury is the result of the systemic release of mitochon- drial damps, because blockade of fpr or deletion of tlr- significantly reduced lung injury. from their results, the investigators summarize a mechanistic model for apap-induced liver damage and lung inflammation. apap-initiated hepatocyte necrosis causes the release of mitochondrial damps and che- mokines, which lead to hepatic recruitment of neutro- phils that amplify liver damage. the release of mito- chondrial damps also triggers systemic inflammation and causes organ injury at remote sites. many studies clearly support that neutrophils are recruited into the liver after cellular damage initiated by apap challenge. however, the key unresolved ques- tion is whether or not the infiltrated neutrophils are activated and aggravate aili. data from some studies, including the present one, provide evidence for a path- ological role of neutrophils in aili. however, other studies have demonstrated that ( ) neutrophils recruited into the liver are not activated, ( ) blocking neutro- phil recruitment does not affect aili, , and ( ) even activating neutrophils by endotoxin or interleukin (il)- b does not worsen aili. , aside from the dichot- omy of tissue-damaging and -repair functions of neu- trophils, these discrepancies can be, at least in part, explained by different experimental protocols employed by various research groups. for example, two critical experimental conditions that can significantly affect the severity and kinetics of aili include the mouse strains, as well as the dose and route of administration of apap. therefore, direct comparisons can only be made when the experimental approaches are unified. cynthia ju, ph.d. school of pharmacy university of colorado health sciences center denver, co references . larson am, polson j, fontana rj, davern tj, lalani e, hynan ls, 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interleu- kin- beta in acetaminophen-induced hepatic inflammation and liver injury. toxicol appl pharmacol ; : - . hepatology, vol. , no. , ju modeling of a heater load in residential buildings for demand response modeling of a heater load in residential buildings for demand response amrutha maria mathew pg scholar saintgits college of engineering, kerala, india rishi menon assistant professor saintgits college of engineering, kerala, india abstract—intermittent renewable energy resources such as, wind and photovoltaic (pv) plays a considerable role in today’s power generation. in order to compensate this highly variable generation demand response is employed as a part of demand side management instead of costlier generation side spinning reserves. this capability can be achieved through responsive electric devices such as electric water heaters. simulation model of the dr loads (heater) is mainly focused in a building considering the indoor and outdoor conditions. this paper presents a new approach for modeling flexible loads and aims to create further knowledge on the potentials of residential demand response concepts. the simulations are performed in matlab software. keywords—demand response(dr),dsm,matlab i. introduction future grid requires greater penetration of renewable capacity integrated in to the system. in the power system, the system load keeps changing from time to time according to the needs of the consumers. the electricity system must continuously be balanced to maintain a secure operation. today, mainly generation is used to achieve the balance, while electricity demand has a passive role. the electricity demands can be used as a new measure for fast reserves. grid friendly appliances, such as refrigerators, water or space heaters ventilation systems and air conditioners help to manage energy imbalance. potential for demand response is vast and there are many loads which can be used with this technique. the participating loads can self adjust their use of electricity i.e. they can be turned off for a short duration without any inconvenience to the customers. regulating the use of energy has recently become critical due to the concerns of the energy crisis. demand response enables customers to adjust their electricity usage to balance supply and demand. demand response is a dsm solution that targets residential, commercial, and industrial customers, and is developed for demand reduction or demand shifting at a specific time for a specific duration. in the absence of on-site generation or the possibility of demand shifting, the consumption level needs to be lowered to comply with a dr event. the non-criticality of loads at the residential and commercial levels allows for demand reduction with relative ease. combined with their cyclic on/off switching behavior, they present ideal solution for frequency controlled reserve and flexible implementation of the dr technique. ii. lumped thermal model of a building assumption in the lumped model is that indoor air temperature and the temperature of all internal layers are the same.i.e, lumped thermal capacity of the building = sum of the internal capacities of all internal layers temperature change in a building due to transmittive and ventilation heat losses, 𝐶 𝑑𝑇𝑖𝑛 (𝑡) 𝑑𝑡 = 𝑈𝐴[𝑇𝑜𝑢𝑡 − 𝑇𝑖𝑛 (𝑡)] + 𝑛(𝜌𝑐𝑝)𝑉 [𝑇𝑣𝑒𝑛𝑡 − 𝑇𝑖𝑛 (𝑡)     fig. . thermal model of a building. international journal of engineering research & technology (ijert) issn: - www.ijert.orgijertv is (this work is licensed under a creative commons attribution . international license.) vol. issue , july- fig. . indoor and outdoor temperature variations. iii.heater with p controller the control logic behind the heater is given below. { 𝑄 = 𝑖𝑓 𝑇𝑖𝑛 > = 𝑖𝑓 𝑇𝑖𝑛 < } ( ) fig. . heater load in a building with p controller. fig. shows the thermal model of a building with a heater load. outdoor temperature is periodically varying in nature. heater load is included in the category of thermostatically controlled loads. they can be switched off for a short period of time without any disturbance to the consumers. the set temperature value is compared with indoor temperature of the building and the resulting error signal is given as a feedback to the heater load in the building and the necessary control action is performed. when the indoor temperature is greater than the set temperature point there is no heat flow, otherwise heat exchange takes place. fig. shows the indoor and outdoor temperature variations and gain with the heater load. table building parameters fig. . indoor and outdoor temperature variations and gain with controller. iv.conclusion this paper develops thermal model of a building with a heater load to accurately capture their behavior for demand response. the simulation results show that heater loads are best suitable for demand response programs. this is tested under both steady state and dynamically varying conditions caused by temperature set point changes. it also accounts for the dynamics of the solid mass of the buildings. references [ ] z. xu, j. stergaard, and m. togeby,“demand as frequency controlled reserve,” ieee trans. power syst., vol. . [ ] j. a. short, d. g. infield, and l. l. freris, “stabilization of grid frequency through dynamic demand control,” ieee trans.power syst., vol. , no. , . [ ] mohammad r. vedady moghadam, richard t. b.ma, andrui zhang, “distributed frequency control in smart grids via randomized demand response,” ieee transactions on smart grid vol. , no. . [ ] he hao, borhan m. sanandaji, kameshwar poolla, and tyrone l. vincent, “aggregate flexibility of thermostatically controlled loads,”ieee transactions on power electronics,vol , no. , january. . [ ] s. z. althaher and j. mutale, “management and control of residential energy through implementation of real time pricing and demand response,” ieee transactions on power systems . [ ] a. molina-garca, f. bouffard, and d. s. kirsche “decentralized demand-side contribution to primary frequency control,” ieee trans. power syst., vol , no. , . [ ] wei liu,wei gu,wanxing sheng and xiaoli meng,“decentralize multi-agent system-based cooperative frequency control for autonomous microgrids with communication constraints,” ieee transactions on sustainable energy, april . tout tvent u a v n . international journal of engineering research & technology (ijert) issn: - www.ijert.orgijertv is (this work is licensed under a creative commons attribution . international license.) vol. issue , july- wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ june , volume , number american association for fool the advancement of science as f science serves its readers as a forum for the presenta- tion and discussion of important issues related to the ad- relatec vancement of science, including the presentation of mi- tinues nority or conflicting points of view, rather than by pub- lishing only material on which a consensus has been lem of reached. accordingly, all articles published in science- including editorials, news and comment, and book re- comes views-are signed and reflect the individual views of the a more authors and not official points of view adopted by the aaas or the institutions with which the authors are af- hun filiated. malnul editorial board among : richard e. balzhiser, wallace s. broeck- chroni er, clement l. markert, frank w. putnam, bry- ant w. rossiter, vera c. rubin, maxine f. singer, the po paul e. waggoner, f. karl willenbrock : peter bell, bryce crawford, jr., e. peter est ma geiduschek, emil w. haury, sally gregory nouris kohlstedt, mancur olson, peter h. raven, wil- billion liam p. slichter, frederic g. worden publisher are ch william d. carey hun itor the pr philip h. abelson and ac editorial staff er wer managing editor business manager hungei robert v. ormes hans nussbaum assistant managing editor production editor must john e. ringle ellen e. murphy the de news editor: barbara j. culliton sents i news and comment: william j. broad, luther j. carter, constance holden, eliot marshall, fully u deborah shapley, r. jeffrey smith, nicholas be abl wade, john walsh. editorial assistant, scherraine mack jected research news: beverly karplus hartline, le richard a. kerr, gina bari kolata, jean l. proble marx, thomas h. maugh ii, arthur l. robinson. ders; 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( - - ). chanc advertising correspondence: tenth floor, broadway, new york, n.y. . phone: - *the fin - . rial is ep science d, the hidden crisis familiar as the energy crisis is to all of us, there is another, energy- d crisis that has been recurring since the beginning of history and con- to plague us today. that is the international food supply and the prob- f world hunger. in many ways, world hunger is a hidden crisis, for it to our attention only in a sporadic fashion. yet it probably represents e explosive threat to world peace than does nuclear proliferation. iger comes in several varieties. one is literal starvation. another is itrition (nutritional imbalance), which is far from uncommon, even g the affluent. today, however, the major variety of world hunger is ic undernutrition, a problem preponderantly though not exclusively of sorer nations. the united nations food and agriculture organization ltes that as of around million people were chronically under- ,hed. calculating differently, the world bank put the figure at above i l-one-quarter of the population of the earth. more than half of them iildren, and more of them are women than men. nger is not an inevitable part of the human condition. in our report*, ,esidential commission on world hunger declares that "if decisions :tions well within the capability ofnations and people working togeth- re implemented, it would be possible to eliminate the worst aspects of 'rand malnutrition by the year ." to accomplish this goal, we increase our efforts to redress the imbalance of food supplies between bveloped nations and the less-developed nations, where hunger pre- its starkest face. unfortunately, most projections show that even if we inleashed our total agripower, the united states alone still would not le to meet the levels of food demand in the developing countries pro- lfor the year . obviously, the solution to the food and hunger xm in the countries of the developing world lies within their own bor- they must build a self-reliant system of food production and distribu- of the major obstacles to achieving such self-reliance is energy- d. much of the highly vaunted agricultural productivity in the d states is due to agricultural research based on energy-intensive alogy. until recently, this same approach was carried over into ransmission of our research and technology to the developing thus, the developing countries have been holding their own in the w years largely because of strategies and techniques developed as part so-called green revolution. because of their higher rates of popu- growth, these countries have had to achieve food production growth that are higher than those of the developed nations just to stay where ire on a per capita basis. this the green revolution has helped them to 'he elements of the green revolution, however, are primarily im- d plant varieties, chemical fertilizers, irrigation, and mechanization- sil fuel-intensive. earch efforts are now shifting away from energy-intensive technology. ew focus is on greater photosynthetic efficiency, more efficient nutri- id water uptake, improved biological nitrogen fixation, and breeding ic resistance to pests and environmental stress. these highly sophisti- promising areas of research will require marshaling of the best scien- llent in both the united states and the developing world. whether it res germ plasm banks or somatic hybridization, the effort will entail a )orative approach by u.s. agricultural experiment stations, inter- ial agricultural research centers, and scientific institutes in the less- )ped nations. -he long run, we must recognize that knowledge itself-theory, inven- discovery, technology-and human skills must be shared globally if orld hunger problem is to be solved.-clifton r. wharton, jr., 'ellor, state university of new york, albany al report of the commission was submitted to president carter in march . this edito- xcerpted from the author's address to the economic club of detroit on march. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ food, the hidden crisis cr wharton jr doi: . /science. ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the trademark of aaas. is a registeredscienceadvancement of science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for thescience science. no claim to original u.s. government works. copyright © the authors, some rights reserved; exclusive licensee american association for the advancement of o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ [pdf] overcoming an energy crisis?: an adaptive role of glycogen synthase kinase- inhibition in ischemia/reperfusion. | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . / .res. . .b corpus id: overcoming an energy crisis?: an adaptive role of glycogen synthase kinase- inhibition in ischemia/reperfusion. @article{zhai overcomingae, title={overcoming an energy crisis?: an adaptive role of glycogen synthase kinase- inhibition in ischemia/reperfusion.}, author={p. zhai and j. sadoshima}, journal={circulation research}, year={ }, volume={ }, pages={ - } } 	p. zhai, j. sadoshima 	published 	medicine, biology 	circulation research a prolonged period of ischemia leads to death of cardiac myocyte (myocardial infarction). in theory, quicker restoration of blood supply to the ischemic myocardium should reduce the extent of myocardial injury. however, reperfusion itself has the potential to exacerbate myocardial damage, a phenomenon known as reperfusion injury. mitochondrial dysfunction plays a central role in mediating myocardial cell death by ischemia/reperfusion (ir). in particular, opening of the mitochondria permeability… expand view on pubmed ahajournals.org save to library create alert cite launch research feed share this paper citationshighly influential citations background citations view all topics from this paper 	adenosine triphosphate 	glycogen synthase kinase 	glycogen synthase kinases 	hypoxia 	ischemia 	adenine nucleotides 	creatine 	glycolysis 	glycogen (starch) synthase 	reperfusion injury 	glucose 	myocytes, cardiac 	cardiomyopathies 	reperfusion therapy 	mitochondrial membranes 	myocardial infarction 	cessation of life 	benzodiazepines 	threonine 	mitochondrial diseases 	voltage-dependent anion channels 	cell death 	 -phosphatidylinositol -kinase 	reactive oxygen species 	oxidative stress citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency inhibition of glycogen synthase kinase β prevents nsaid-induced acute kidney injury 	h. bao, y. ge, s. zhuang, l. dworkin, z. liu, r. gong 	biology, medicine 	kidney international 	 	 	 save alert research feed gsk β and vdac involvement in er stress and apoptosis modulation during orthotopic liver transplantation 	m. zaoualí, a. panisello, + authors j. roselló-catafau 	medicine 	international journal of molecular sciences 	 	 	pdf 	view excerpts, cites background save alert research feed signal transduction pathways involved in drug-induced liver injury. 	d. han, m. shinohara, m. ybanez, b. saberi, n. kaplowitz 	biology, medicine 	handbook of experimental pharmacology 	 	 save alert research feed glycogen synthase kinase ‐mediated voltage‐dependent anion channel phosphorylation controls outer mitochondrial membrane permeability during lipid accumulation 	c. martel, maya allouche, + authors c. brenner 	biology, medicine 	hepatology 	 	 	pdf 	view excerpt, cites background save alert research feed protective potential effects of fucoidan in hepatic cold ischemia-rerfusion injury in rats. 	chérifa slim, m. zaoualí, + authors h. abdennebi 	chemistry, medicine 	international journal of biological macromolecules 	 	 save alert research feed the role of the l-type ca + channel in altered metabolic activity in a murine model of hypertrophic cardiomyopathy 	h. viola, victoria p. a. johnstone, + authors l. hool 	biology, medicine 	jacc. basic to translational science 	 	 	highly influenced 	 	view excerpts, cites background save alert research feed role of the cytoskeleton in communication between l‐type ca + channels and mitochondria 	h. viola, l. hool 	biology, medicine 	clinical and experimental pharmacology & physiology 	 	 	pdf save alert research feed how does calcium regulate mitochondrial energetics in the heart? - new insights. 	h. viola, l. hool 	medicine 	heart, lung & circulation 	 	 	pdf 	view excerpt, cites background save alert research feed role of b-type natriuretic peptide in epoxyeicosatrienoic acid-mediated improved post-ischaemic recovery of heart contractile function. 	k. chaudhary, s. n. batchu, + authors j. seubert 	biology, medicine 	cardiovascular research 	 	 	pdf save alert research feed the l‐type ca + channel facilitates abnormal metabolic activity in the ctni‐g s mouse model of hypertrophic cardiomyopathy 	h. viola, v. johnstone, + authors l. hool 	biology, medicine 	the journal of physiology 	 	 	highly influenced 	 	view excerpts, cites background save alert research feed ... ... references showing - of references sort byrelevance most influenced papers recency isoflurane postconditioning prevents opening of the mitochondrial permeability transition pore through inhibition of glycogen synthase kinase β 	jianhua feng, e. lucchinetti, p. ahuja, t. pasch, j. perriard, m. zaugg 	medicine 	anesthesiology 	 	 	pdf save alert research feed modulation of the mitochondrial permeability transition pore complex in gsk- beta-mediated myocardial protection. 	m. nishihara, t. miura, + authors k. shimamoto 	biology, medicine 	journal of molecular and cellular cardiology 	 	 save alert research feed inhibition of glycogen synthase kinase- beta improves tolerance to ischemia in hypertrophied hearts. 	rodrigo barillas, i. friehs, h. cao-danh, j. f. martinez, p. d. del nido 	medicine 	the annals of thoracic surgery 	 	 	 save alert research feed the role of mitochondria in protection of the heart by preconditioning 	a. halestrap, s. clarke, i. khaliulin 	biology, medicine 	biochimica et biophysica acta 	 	 	 save alert research feed myocardial ischemia/reperfusion causes vdac phosphorylation which is reduced by cardioprotection with a p map kinase inhibitor 	h. schwertz, j. carter, + authors m. buerke 	chemistry, medicine 	proteomics 	 	 save alert research feed glycogen synthase kinase- β mediates convergence of protection signaling to inhibit the mitochondrial permeability transition pore 	m. juhaszova, d. zorov, + authors s. sollott 	biology 	 	 	pdf save alert research feed bradykinin prevents reperfusion injury by targeting mitochondrial permeability transition pore through glycogen synthase kinase beta. 	sung-sik park, h. zhao, r. mueller, zhelong xu 	chemistry, medicine 	journal of molecular and cellular cardiology 	 	 save alert research feed glycogen synthase kinase- inactivation is not required for ischemic preconditioning or postconditioning in the mouse 	y. nishino, i. webb, + authors m. marber 	medicine 	circulation research 	 	 	 save alert research feed mitochondrial permeability transition pore opening as an endpoint to initiate cell death and as a putative target for cardioprotection 	s. javadov, m. karmazyn 	biology, medicine 	cellular physiology and biochemistry 	 	 	 save alert research feed transgenic expression of bcl- modulates energy metabolism, prevents cytosolic acidification during ischemia, and reduces ischemia/reperfusion injury 	kenichi imahashi, m. schneider, c. steenbergen, e. murphy 	biology, medicine 	circulation research 	 	 	pdf save alert research feed ... ... related papers 	abstract 	topics 	 citations 	 references 	related papers stay connected with semantic scholar sign up about semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue a triboelectric nanogenerator based on cosmetic fixing powder for mechanical energy harvesting xia et al. microsystems & nanoengineering ( ) : microsystems & nanoengineering https://doi.org/ . /s - - - www.nature.com/micronano a r t i c l e op e n a c c e s s a triboelectric nanogenerator based on cosmetic fixing powder for mechanical energy harvesting kequan xia , yue chi , jiangming fu , zhiyuan zhu , hongze zhang , chaolin du and zhiwei xu abstract in this work, we use commercial powder particulates (a cosmetic fixing powder) as triboelectric materials for constructing a triboelectric nanogenerator (cfp-teng). through finger pressing, the cfp-teng generated approximate open-circuit voltage, short-circuit current, and maximum power density values of v, µa, and . μw/cm , respectively. thirty-seven commercial blue leds can be easily lit up by the cfp-teng. moreover, this teng, which was designed as a novel palette structure for harvesting mechanical energy from bicycle motion, serves as a self-powered bicycle speed sensor. in addition, the cosmetic fixing powder can be used as an effective material to enhance the triboelectric property of skin. this study provides an effective method for developing a cost-effective teng without the use of complex surface micro-/nano-texturing. introduction the global energy crisis is becoming increasingly severe with the fast-paced growth of the global economy – . moreover, with the continued acceleration of human civilization, exhaustion of fossil energy in the first half of the twenty-first century is expected , . renewable energy for electricity generation has been considered a means of solving the energy crisis – . solar energy, tidal energy, mechanical motion, and thermal changes are all con- sidered potential forms of energy that are convertible into electrical energy in the environment. among these, mechanical energy is the most extensively distributed type, as it occurs in diverse forms , . daily activities such as walking, running, cycling, and even tiny facial expres- sions (for example, smiling and crying) are accompanied by mechanical distortions, suggesting that the human body constitutes a pivotal means of mechanical power generation , . however, it is difficult to apply traditional electromagnetic induction generators for harvesting mechanical energy from the surrounding environment (human daily activities, etc.). in , prof. zhonglin wang (georgia institute of technology) proposed the first-ever triboelectric nano- generator (teng), which converts mechanical energy from the surrounding environment into electrical energy on the basis of the triboelectric effect – . during the past few years, the teng has received considerable attention and has been widely applied to multidisciplinary fields owing to its outstanding output performance, sus- tainable power output, and ease of integration – . sev- eral materials (for example, pdms, kapton, al, and teflon, each with its own merits and demerits) have been applied to the construction of tengs – . although silica-based powder is also used as one of the triboelectric pair , the output voltage is relatively low (~ v). the triboelectric substances proposed for teng construction should (ideally) be low cost, yield rapidly self-forming films, be processable without the need for cumbersome micro-/nano-processing, and (if possible) be readily available. in this work, we propose a novel concept of a powder teng that uses powder particulates (for example, © the author(s) openaccessthisarticleis licensedunderacreativecommonsattribution . internationallicense,whichpermitsuse,sharing,adaptation,distributionandreproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the creative commons license, and indicate if changes were made. the images or other third party material in this article are included in the article’s creative commons license, unless indicated otherwise in a credit line to the material. if material is not included in the article’s creative commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. to view a copy of this license, visit http://creativecommons.org/licenses/by/ . /. correspondence: zhiyuan zhu (zyzhu@zju.edu.cn) or zhiwei xu (xuzw@zju.edu.cn) ocean college, zhejiang university, zhejiang, china nanjing electronic devices institute, jiangsu, china () :,; () :,; () :,; () :, ; www.nature.com/micronano http://creativecommons.org/licenses/by/ . / mailto:zyzhu@zju.edu.cn mailto:xuzw@zju.edu.cn cosmetic fixing powder) as triboelectric materials for fabricating a triboelectric nanogenerator (cfp-teng). this fabrication, which is realized without the use of surface micro-/nano-texturing techniques that rely on expensive equipment and complex technology, may drive the large-scale application of tengs in multidisciplinary fields. in our work, this powder and teflon tape were used as the triboelectric pair. the cfp-teng can, through finger pressing, produce approximate open-circuit vol- tage, short-circuit current, and power density values of v, µa, and . μw/cm , respectively. thirty- seven commercial blue leds, which were assembled into the word “zju”, could be lit up by the cfp-teng. in addition, this teng, which was designed as a novel pal- ette structure to harvest mechanical energy from bicycle motion, serves as a self-powered speed sensor. in addition, the cosmetic fixing powder can be used as an effective material to enhance the triboelectric property of skin, which is significant for the development of a human- based teng. results the design and fabrication process of the cfp-teng device is schematically presented in fig. . first, a sheet of paper was cut into two pieces of paper substrate (size: cm × cm), as shown in fig. a. a piece of copper tape ( cm × cm) was then pasted onto the paper surface (see fig. b). subsequently, teflon tape was pasted onto the surface of the copper tape, thereby forming the top sec- tion of the teng, as shown in fig. c. another paper substrate was obtained by pasting the double-sided tape onto the paper substrate surface, as shown in fig. d, and then attaching the copper to the surface of the tape. afterward, the cosmetic fixing powder was applied onto the glue side of the copper tape. excess powder was then removed by air blowing, thereby forming the bottom section of the teng (see fig. e, f). a piece of poly- ethylene terephthalate (pet) film served as the supporting structure for assembly of the teng, as illustrated in fig. g. figure a, b shows photographs of the cfp-teng (one unit) and the stacked cfp-teng. representative scan- ning electron microscopy images showing the surface of the teflon tape and cosmetic fixing powder layer are stickinga b c g d e f h sticking assembling gum ptfe copper paper pet double-side tape powder foundation pr es sin g sticking sticking fig. preparation process of the cfp-teng a teng μm μm stacked teng b c d fig. images of the device and triboelectronic surfaces. photographs of the a cfp-teng unit and b stacked cfp-teng. sem image of the c teflon tape surface and d cosmetic fixing powder layer surface xia et al. microsystems & nanoengineering ( ) : page of presented in fig. c, d. a mechanical vibrator was used to activate the cfp-teng. the top and bottom of the teng were affixed to the pressing surface of the vibrator and a flat panel, respectively. the respective electrical output signals were then measured with a digital oscilloscope. the working principle of the cfp-teng is schemati- cally illustrated in fig. . when teflon tape is in contact with cosmetic fixing powder, electron transfer from the powder layer to the tape (fig. a). a latent electrical dif- ference is expected with separation of the tape from the powder. this type of latent difference drives the electron flow via the external loads from the top cu foil to the bottom cu foil. this flow screens the positive triboelectric charges available on the paper, thereby producing an output current signal (fig. b). a new electrical equili- brium is expected at the largest separation in a complete contact–separation cycle (fig. c). subsequent to this equilibrium, contact between the teflon tape and the cosmetic fixing powder layer is re-established, leading to an imbalance between the stimulated charges on the cu electrodes. this imbalance results in electron flow back to the top cu foil, thereby producing a reversed output current signal (fig. d). when full contact between the tape and paper is re-established, the cfp-teng reverts to its initial position, as shown in fig. a. to understand this mechanism, the latent distribution is simulated with comsol multiphysics software. an open-circuit a releasing r r r r i i pressing – – – – – – – – copper teflon tape gum cosmetic fixing powder approaching separating b d e (i) (ii) (iii) c fig. schematic and modeling analysis of the device. a–d working principle of the cfp-teng. e numerical calculations (as assessed with the help of comsol) of the potential distribution across teng electrodes, at each step (i–iii), subjected to open-circuit conditions (the voltage unit is volts) xia et al. microsystems & nanoengineering ( ) : page of scenario is considered for the three positions of the one- unit cfp-teng (see fig. e). an adjustable resistor ( kΩ to gΩ) was used as the external load of the fabricated tengs, and the electronic voltage on the resistor was measured. the output current can be derived from the measured voltage and the total resistance. the voltage (under a gΩ load) and current (under a kΩ load) of the fabricated cfp-teng are v and . μa, respectively (see fig. a, b), when triggered by a mechanical vibrator (amplitude: ∼ cm, frequency: hz). for the reverse connection of the oscilloscope to the cfp-teng, the output voltage and current signals are inverted (as shown in fig. d, e), which indicates that the signals were generated by the cfp- teng. considering the mΩ probe of the oscillo- scope, the total resistance can be calculated by rt = r × mΩ/(r + mΩ), and the corresponding output performance of cfp-teng is further investigated by evaluating the output power associated with the voltage and current occurring at equivalent total resistances ranging from . kΩ to . mΩ (see fig. c). with increasing total resistance, the current amplitude decreases owing to a loss of resistance, whereas the vol- tage increases. in addition, an approximate maximum power density value of . μw/cm corresponding to a total resistance of ∼ mΩ (see fig. f) is obtained. in addition, the output performances with and without cosmetic fixing powder are compared in the supporting information. the electronic output performance of the cfp-teng, based on contact separation, exhibits a high dependence on the contact frequency, separation distance, and device size. figure a, b shows the dependence of the voc and isc values of cfp-teng on contact frequency for a given device size and separation distance of cm × cm and mm, respectively. moreover, the output voltage increases from to v when the contact frequency increases from to hz. nonetheless, the isc increases continuously from . to . μa when the contact frequency increases from to hz. the increase in the isc and voc values is attributed to the rapid induction and charge transfer resulting from the elevated frequency contact. figure c, d shows the voc and the isc values of the ( cm × cm) cfp- teng as a function of the separation distance. further- more, with increasing separation distance, the voc increa- ses slowly and then saturates, while the isc increases continuously. the voc and isc values corresponding to a contact frequency and separation distance of hz and mm, respectively, of tengs with varied sizes are shown in fig. e, f. as the figure shows, voc and isc increase with increasing device size. the substantial enhancement in the output is attributed to the augmented contact region. detailed discussions of the impact of the separation dis- placement and frequency on the electrical performance are provided in the supporting information. furthermore, a stacked cfp-teng is designed and manufactured to improve the output efficiency. the isc values of the stacked cfp-tengs with , , and units are , , and μa, respectively (see fig. g). the results revealed that the output current increases with increasing number of units. similarly, the stability of the cfp-teng is evaluated from the findings presented in a b c d e f v o lta g e ( v ) v o lta g e ( v ) c u rr e n t (μ a ) c u rr e n t (μ a ) c u rr e n t (μ a ) – – – – v o lta g e ( v ) p o w e r (μ w ) r v teng – – – – – – – time (s) time (s) total resistance (mΩ) time (s) time (s) total resistance (mΩ) fig. electrical output of the device. output voltage and current of the cfp-teng calculated using the a, b forward connection and d, e reverse connection. dependence of c the output voltage and current on the total resistance and f the power density on the total resistance xia et al. microsystems & nanoengineering ( ) : page of fig. h. in accordance with the experimental results, a stable output voltage from the cfp-teng is realized even after a -cycle external force test. according to a previous study , the human body pro- duces hundreds of watts through body movements. therefore, harvesting low-frequency power generated by human physical movements is considered a potential means of realizing self-powered wearable electronics. in this work, we demonstrate that a cfp-teng ( cm × cm) can be activated via finger pressing (see fig. f). as a b c d e f g h hz mm mm mm mm mm mm mm mm mm mm mm mm mm mm unit unit unit unit mm mm mm mm hz hz hz hz hz hz hz hz hz hz hz i s c (μ a ) i s c (μ a ) i s c (μ a ) v o c (v ) – – – time (s) time (s) time (s) time (s) time (s) time (s) time (s) time (s)time (s) i s c (a ) – – – – – v o c (v ) v o c (v ) v o c (v ) v o c (v ) – – – – – – cycles – – – – – – – fig. performance and stability of the device. approximate values of voc and isc at various a, b frequencies (cfp-teng size: cm × cm, maximum separation distance: mm), c, d separation distances (mechanical frequency: hz, cfp-teng size: cm × cm), and e, f cfp-teng sizes (working frequency: hz, separation distance of the teng: mm. g output current of the cfp-teng with various unit numbers. h stability verification of the fabricated cfp-teng via cycles of continuous operation xia et al. microsystems & nanoengineering ( ) : page of shown in fig. a, b, isc and voc reach approximate values of μa and v, respectively. when a match load of mΩ (equivalent total resistance: . mΩ) is connected to the cfp-teng, the max- imum output power, corresponding to an output voltage of v and current of . μa, is reached (see fig. c, d). the corresponding maximum output power ( . mw) and power density ( . μw/cm ) are adequate for various low-energy-consumption micro- electronic gadgets. we also performed tests aimed at determining the charging potential of the fabricated cfp-teng connected to a nf capacitor by means of a full-wave rectifier bridge. the results revealed that ∼ nc of charge is transferred in one cycle. discussion to demonstrate the potential of the cfp-teng as an energy source, a cm × cm cfp-teng was linked to commercial blue leds in series (as presented in fig. a–c). the results revealed that the assembly of these leds forming the word “zju” could be easily lit up by the teng. in addition, we propose a novel palette structure for harvesting the mechanical power associated with bicycle movement (see fig. a). moreover, the proposed structure can also monitor the bicycle speed. the corresponding output voltage of the device (under a gΩ load) can reach . , . , and . v for , , and r.p.m., respectively, as shown in fig. b–d. in addition, the a b c d e f v o c (v ) – – – – nc teng v – – – – c u rr e n t (μ a ) – – v o lta g e ( v ) v o lta g e ( v ) – i s c (μ a ) time (s) time (s) time (s) time (s) time (s) finger teng fig. electrical characteristics of the cfp-teng powered by physical movement (finger pressing). approximate a voc and b isc values of the cfp-teng; c output voltage and d current corresponding to a match load of mΩ (equivalent total resistance: . mΩ); e voltage of a nf capacitor linked to the cfp-teng by means of a full-wave rectifier bridge, indicating the quantity of charge transferred in one cycle; and f a cfp-teng triggered by finger pressing xia et al. microsystems & nanoengineering ( ) : page of output voltages subjected to different speeds are shown in fig. e. it is observed that the output voltage is approxi- mately linear to the speed. furthermore, we proposed a new application of a powder- enhanced skin-based teng. in detail, when the skin is made as the triboelectric layer, the output voltage can reach v, as shown in fig. a. when the skin is modified by cosmetic fixing powder, the output voltage can reach v, as shown in fig. b. according to the results, the cosmetic fixing powder can be used as an effective material to enhance the triboelectric property of skin, which is sig- nificant for the development of a human-based teng. a b c fig. driving capability of the device. a a cfp-teng connected in series with commercial blue leds (the inset shows a cm × cm teng); b, c commercial blue leds powered by finger pressing of the cfp-teng copper paper ptfe powder foundation v o lta g e ( v ) speed (r/min) ba e c d r/min r/min r/min v o lta g e ( v ) – – – v o lta g e ( v ) v o lta g e ( v ) – – – – – – time (s) time (s) time (s) fig. harvesting mechanical power associated with bicycle movement. a photograph of a bicycle with a teng (inset shows the palette structure of the teng); b–d output voltage signals corresponding to three movement states ( , , and r.p.m.). e the output voltages subjected to varied speeds xia et al. microsystems & nanoengineering ( ) : page of conclusions a novel concept of powder electronics that use powder particulates (a cosmetic fixing powder) as triboelectric materials for fabricating a teng is proposed in this work. the loose powder and teflon tape are used as the tribo- electric pair. the cfp-teng can generate approximate voc, isc, and maximum power density values of v, µa, and . μw/cm , respectively. stable output voltage from the cfp-teng is realized after a -cycle external force test. in addition, this teng, which was designed as a novel palette structure for harvesting mechanical energy from bicycle motion, serves as a self- powered speed sensor. furthermore, the cosmetic fixing powder can be used as an effective material to enhance the triboelectric property of skin. this work represents a significant step towards the large-scale production of tengs. materials and methods all materials are commercially available and used without further processing. acknowledgements this work was supported by the national natural science foundation of china (grant no. , grant no. , grant no. ) and the aeronautical science foundation of china (grant no. asfc- zc ). the author would also like to thank prof. yufeng jin and prof. min yu from peking university for their previous guidance. authors' contributions k.x. performed the experiment and wrote the paper. z.z. analysed the data and wrote the paper. y.c., j.f., h.z., c.d., and z.x. analysed the data. conflict of interest the authors declare that they have no conflict of interest. supplementary information accompanies this paper at https://doi.org/ . /s - - - . received: january revised: march accepted: march references . ren, x. et al. wind energy harvester based on coaxial rotatory freestanding triboelectric nanogenerators for self-powered water splitting. nano energy , – ( ). . cao, x. et al. inductor-free wireless energy delivery via maxwell’s displacement current from an electrodeless triboelectric nanogenerator. adv. mater. , ( ). . qian, y., du, j. & kang, d. j. enhanced electrochemical performance of porous co-doped tio nanomaterials prepared by a 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nano energy , – ( ). . qian, y. & kang, d. j. large-area high-quality ab-stacked bilayer graphene on h-bn/pt foil by chemical vapor deposition. acs appl. mater. interfaces , – ( ). . kim, i. et al. a triboelectric nanogenerator using silica-based powder for appropriate technology. sens. actuators a phys. , – ( ). . zhang, x. s. et al. all-in-one self-powered flexible microsystems based on triboelectric nanogenerators. nano energy , – ( ). xia et al. microsystems & nanoengineering ( ) : page of https://doi.org/ . /acsnano. b https://doi.org/ . /acsnano. b 	a triboelectric nanogenerator based on cosmetic fixing powder for mechanical energy harvesting 	introduction 	results 	discussion 	conclusions 	materials and methods 	acknowledgments wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . 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interdependence within and between human communities. primitive or primordial interdependence concerns reciprocal reli- ance among kith and kin or within face-to-face societies. feudo-imperial interdependence includes both feudal relations in single societies and imperial relations between societies. these are based on exploitation and hierarchy. mature interdependence comes with egalitarianism and a rational division of labor based on equity under modern conditions. while technology helped to demoralize individual western societies, it also consoli- dated western control of other societies. the internal democratization of the west coin- cided with the stratification of the world under western dominion. how can the third world escape this dominion? one approach is that of disengage- ment ; another is that of counterpenetration. the west’s achilles’ heel is its need of energy from the third world. this need could make the west at least responsive to third world demands for greater equity. successful energy conservation in the west would, on the other hand, be detrimental to third world interests in the short run. the oil-rich third world countries may have beencast by history as temporary leaders of the oppressed in the global system. inequality within the third world could be a neces- sary precondition for the liberation of the third world. the problem of stratification in history has always been linked to the tensions of interdependence. the degree to which people need each other is always at the core of their interrelationships. theories about the consequences of the division of labor, and about the origins of caste, class, and hierarchy have all been at once concerned with issues of stratification and of interdepend- ence. it is clear both from the history of social institutions and of social ideas that interdependence can either create or destroy equality. the critical factor concerns the precise nature of that interdependence. the oil crisis precipitated a reappraisal of the nature of interdependence among nations. discussions have gone on be- tween the european economic community and the arab oil pro- ducers concerning the possibility of exchanging european tech- nology for arab oil in a bid for mutually induced economic devel- opment. the american government has explored ways of strength- ening relations between western europe and the united states in search of a new economic basis for the atlantic partnership. the united nations has discussed the problem of raw materials in relation to international trade, and one eminent speaker after another has called for a new definition of international inter- dependence. but central to all these discussions and debates has been the ancient moral problem-the problem of equality. in this article we distinguish three stages of interdependence: primitive, feudo-imperial, and mature. we define primitive inter- dependence to be the cooperative relationship which exists in conditions of rudimentary technology and limited social hori- zons. the second type of interdependence is the feudo-imperial, which combines some of the characteristics of feudalism with some of the attributes of imperialism. a central characteristic of this kind of interdependence is hierarchy, and hierarchy is of course founded on the premise of inequality. the third, or mature, stage of interdependence is one which combines sophistication with symmetry. the sophistication comes from enhanced technological capabilities and expanded social and intellectual awareness; the symmetry emerges out of a new egalitarian morality combined with a more balanced capacity for mutual harm. the different parties must not only need each other but their different needs ought to be on a scale which makes possible serious mutual dislocations in case of con- flict. the combination of an egalitarian ethic and reciprocal vul- nerability, within the framework of wider technological and intel- lectual frontiers, provides the essence of mature interdependence. we propose to demonstrate in this article that relations among nations in the first three-quarters of this century have been primarily feudo-imperial, deprived of both the kinship solidarity of primitive interdependence and the sophisticated symmetry of mature interdependence. one of the most important questions confronting us is whether or not we are at last about to evolve a genuine pattern of mature interdependence before this century comes to a close. behind this issue is the all-powerful variable of technological change. we propose to illustrate that technological change within individual societies influenced the transition first from primitive to feudo-imperial interdependence, and then, more recently, from feudo-imperial to the beginnings of mature interdependence. the question also arises as to whether or not technological change on the international scale could in turn facilitate in the last quarter of the twentieth century the transformation from feudo- imperial relationships between the developed northern hemi- sphere and the underdeveloped southern hemisphere to inter- action on a mature plane. the energy crisis may have opened up new possibilities as it revealed the inner vulnerability of feudo- imperial relationships as they have hitherto existed in inter- national affairs. technological change and social imbalance the principal factor behind europe’s rise to imperial pre- eminence was its technological revolution which set the stage for european expansion and colonization. the industrial revolution created disparities between the western world on the one hand and much of the rest of the world on the other. technology within england and america from the eighteenth century onwards helped to lay the foundations of a more egalitarian england and even a more egalitarian america; yet that same technology, by increasing the inventive and produc- tive capabilities of these societies far beyond those attained by others, initiated a process of massive disparities of income and power among the nations of the world. technology in the west served domestically as an equalizing process partly by destroying the traditional legitimation of hierarchy. the industrial revolution in england produced new challenges from the middle classes against the ancient privileges of the landed aristocracy. pressures began to mount for social and political reform as trade, commerce, and expanded manufactur- ing capabilities produced new levels of work among the bour- geoisie. the previous revolution of the seventeenth century in england had decided the issue between king and parliament in favor of parliamentary preeminence. but, by the eighteenth and nineteenth centuries, the issue was: who controlled parliament itself? the great reform bill put forward a new basis of parliamentary composition, and therefore legislative power. as the nineteenth century entered its second half, pressures mounted for the expansion of the franchise to include the new urban proletariat. this group’s enfranchisement was followed by that of rural workers as the century came to a close. the industrial revolution itself was at the heart of these elec- toral and political reforms. the massive migration of people from the countryside to the cities, the growing restlessness of the newly urbanized, the pressures and social ills of new concentrations of populations, and the rise of political consciousness among the masses, all prepared the way for the process of social equalization in industrial societies. workers began to sense the need for organization, the principle of collective bargaining entered the economic arena. the full consolidation of trade unions in the west was not complete until the twentieth century. for a while legislation was used to discourage organization among workers. nevertheless, the momentum of proletarian self-consciousness was under way. both trade unions and rudimentary socialist parties began to take shape in the second half of the twentieth century in much of the western world. the late nineteenth century was, of course, also the period which saw the emergence of egalitarian thinkers such as karl marx and friedrich engels. new sensibilities concerning the plight of the impoverished, increased awareness of the possi- bilities of income distribution, and growing reluctance to see rank and status as immutable were all part of this process of techno- logical equalization. but the industrial revolution was at the same time pushing western europe and, later, north america further and further ahead in global terms. the western world was increasing its social and economic distance from the rest of mankind, while at the same time narrowing rank and status within itself. three types of technology were particularly important in the rise of the west to global preeminence: that of production, of communications, and of violence. the first is what gave rise to the industrial revolution to begin with and what indeed defined its boundaries. the technology of communication, such as advances in seafaring, enhanced later by the invention of the steam engine, went far toward strengthening the west’s capability to penetrate the rest of the world and provided the necessary preconditions for empire building. as for the technology of violence, this gave the western world the edge in military sophistication, resulting in the colonization of asia and africa. western europe, triumphant, created empires larger than any known in history. its superiority in the technology of violence reinforced by the technologies of communication and production, ensured the global preeminence of the western world in the generations which followed. the same technology which was a force for gradual equalization within the western world itself also served to strengthen the west’s domination of the rest of mankind. meanwhile, economic growth in the united states was laying the foundations for new levels of affluence and power. the american experience came to demonstrate even more sharply the fact that technological change was a force both for domestic equalization and international disequilibrium. at least in rhetoric, the united states was one of the earliest modern experiments in the doctrines of both interdependence and egalitarianism. federalism as a system of government is dominantly a doctrine of interdependence among coordinating elements. the american federal experiment brought into the arena of modern political institutions an innovative exercise in institutionalized interdependence. the original thirteen colonies later recruited additional constituent elements into this partner- ship to create an enduring if sometimes convulsed pluralistic polity. but the united states was also born on a wave of egalitarian rhetoric. the american declaration of independence asserted the conviction that all men were created equal, and proceeded to draw an elaborate social contract theory from that premise. a major theme of inequality has persisted in the american political system from its inception to the present day. this theme touches the issue of race relations. at the time of the declaration of independence, the united states already had an elaborate system of plantations and domestic slavery. this situation con- tinued for several decades despite the american affirmation of human equality. yet once again it was neither america’s political rhetoric nor even a wider and older christian morality which created condi- tions for the termination of slavery. it was, in fact, technological change. as the industrial revolution got under way, new tech- niques of production were perfected, and new methods of trade and exchange evolved between the united states and western europe. the latter was finding that the old triangle of trade, involving slaves from west africa to the americas and other merchandise between the americas and europe, was no longer efficient. the rise of humanitarian concern in europe was sub- stantially stimulated by the emergence of new methods of produc- tion and general technological improvements. it was the teach- ings of neither john locke nor jesus christ that ultimately created a responsive constituency for the abolitionists in europe and the americas. it was the discovery that prosperity no longer needed slavery in the old sense. thus, it was the new technology, assisted to some extent by the new science, that helped the process of equalization. the same technology which effectively ended the slave trade nonetheless also helped to expand imperialism. the status of blacks within the americas was slightly improved after abolition, but within the african continent it was exposed to new levels of penetration and subjugation as a result of the western world’s mastery of the new technology. the various powers of europe carved out large chunks of the african continent, and human history entered its most elaborate state of feudo-imperial rela- tionships. the united states itself did not venture far into the game of outright annexation of territory. there was territorial expansion within the north american continent itself, and there was also the occupation of the philippines. in general, however, the united states preferred economic imperialism without territorial annexation. latin america provides an example: having acquired formal independence from spain and portugal, it subsequently became increasingly vulnerable to penetration and manipulation by the united states. the monroe doctrine, which ostensibly intended to keep european powers from meddling in the affairs of the american hemisphere, became in effect a doctrine to legitimize intervention instead by the united states, creating a relationship certainly akin both to feudalism and to imperialism. at the global level, the united states grew to become the richest and most industrially developed country in the world. the dis- tance between the united states and a country like niger, mali, or tanzania in terms of affluence and technological sophistication illustrates that powerful tendency of modern technology to widen disparities beyond anything conceived a few generations earlier. the northern hemisphere as a whole consumed a staggeringly disproportionate share of the scarce resources of the world, con- ducted the bulk of international trade, consumed a vast amount of raw materials, controlled much of the world’s finance, and enjoyed the highest standards of living ever attained in human history. the third world was overshadowed in both living stand- ards and outright power. to some extent the relationships between the &dquo;have&dquo; and the &dquo;have-not&dquo; nations was a form of interdependence. primary producers, contributing raw materials and oil and other sources of energy to the manufacturing and industrial plants of the north- ern hemisphere, received in return processed goods and products of highly sophisticated technology. it was indeed a system of interdependence, but the interdependence was once again feudo- imperial. the rich countries continued to get richer; the poor remained indigent. the northern hemisphere under the impetus of technological success was widening more than ever the gap existing between itself and the less fortunate sectors of the human race. the strategy of counterpenetration the third world’s response to this stratification requires not only a new relationship among third world countries but also a new relationship between the third world and the dominant northern hemisphere if this economic and political dependence is to be broken. an important school of thought in the third world has opted for the strategy of disengagement. under this strategy the countries of the third world should seek to become self-reliant. when capital is scarce, they should investigate how best to use their own surplus of labor. when advanced skills are scarce, they should use intermediate technology to further develop traditional expertise. there should also be exchange of information and con- sultation among third world countries on these modest techno- logical approaches toward solving their problems. it may some- times make sense to move from the hoe to the plough before one attempts to use the tractor. both the people’s republic of china and the republic of tanzania have been among the countries that have explored the possibilities of self-reliance both by substi- tuting labor-intensive for capital-intensive techniques, and by substituting intermediate technology for the more alluring ad- vanced technology of the western world. the doctrine of disengagement as defined and elaborated in the third world has also put special emphasis on the need for at least partial disengagement from the international capitalist system because the international system of trade and investment is so structured that the full integration of a third world country can only lead to exploitation. for instance, the movement from the developed world to the developing countries of foreign invest- ment and the encouragement of economic development leads to the enforced purchasing of advanced equipment from the donor countries. there is in fact an alternative strategy which, though rich in potential, has yet to command the attention of theoreticians and economic and political analysts. this alternative strategy is what we call the strategy of counterpenetration. it involves not a with- drawal from the international capitalist system but an infiltration of that system to make it more vulnerable to third world pres- sures. if saudi arabia had disengaged itself from the inter- national capitalist system, it would not today be enjoying an amount of economic influence at the international level out of all proportion to its size or level of technological skills. by being substantially integrated through its own resources in the inter- national capitalist system, however, saudi arabia has gradually built within that system an immense economic leverage. until the energy crisis of it was too readily assumed that a country had to be economically developed to be economically powerful. countries measured their international leverage sub- stantially in terms of their technological and demographic size, and seldom in terms of their primary economic products. it was equally assumed that, while the workers in individual industrial countries had acquired domestic power through collective bar- gaining, the poor countries at the international level could not similarly threaten economic action against the northern hemi- sphere. the growth of trade unionism in industrial countries was substantially the growth of a system of collective economic &dquo;blackmail.&dquo; at the international level, however, it continued to seem im- possible that pure primary producers could ever acquire a capacity to threaten &dquo;economic blackmail&dquo; against the northern hemi- sphere. the energy crisis, or more specifically, the readiness of the arabs to use that crisis as a means of exerting international pressure, upset this state of affairs. all of a sudden it looked as if oil as energy could indeed be comparable at the international leyel to labor as energy at the domestic level. new possibilities of inter- national collective bargaining were now on the horizon. in reality, third world leverage against the northern hemi- sphere has varied enormously from country to country. saudi arabia and iran have become substantial actors on the inter- national economic scene, but countries like chad, malawi, and haiti remain on the periphery. similarly, producers of oil might indeed be among the new economic giants of the globe, but this does not make producers of cotton or cocoa equally influential. despite immense variations in power, the fact nevertheless remains that a new mood of political international effectiveness has emerged for third world countries. different subsections are exploring possibilities of establishing cartels of their own in a bid for improved economic justice. the strategy of counterpenetra- tion, therefore, requires not a withdrawal from links with the economies of the northern hemisphere, but an exploration of the possibilities of making that hemisphere reciprocally dependent in a new way. other possibilities of potential counterpenetration exist. the most directly human resource are the pockets of third world populations within the industrial countries themselves. until , west germany imported into its industries large numbers of southern europeans. while southern europeans are not members of the third world proper, their relative underprivi- leged status makes them potential allies of other immigrant workers from outside europe itself. france has significant popu- lations of algerians and other north africans, as well as black africans, involved in its economic life. the number of these people is still relatively modest, and the energy crisis has inter- rupted the flow of such migration into the heartlands of industri- alized europe. but the phenomenon itself could be the beginning of human counterpenetration, since the employment of migrant workers has created conditions at once exploitative in the short run and potentially revolutionary in the years ahead. the most important pocket of the third world within the heartland of the northern hemisphere is, in fact, the black ameri- can population. black americans can be regarded as the second largest black nation in the world, but a black nation which is at the same time part of the most powerful country in the world. the political consciousness of black americans has increasingly included a sensitivity to third world status, and an expanding empathy with the peoples of africa, asia, and latin america. the impact of black americans on the foreign policy of the united states is still very modest. but its potentialities emerge as considerable once we consider the immense, albeit declining, influence of american jews. in october , during the middle eastern crisis, the united states ordered a nuclear alert, implying a readiness to initiate a nuclear war rather than risk the defeat of israel. similarly, the united states senate continues to link the issue of jewish emigration from the soviet union with the issue of what type of economic relationship america should have with russia. the proposal to extend the most favored nation treatment to soviet union has foundered repeatedly in the united states senate against the rock of jewish emigration from russia. the american senators were correctly asserting that the jews in russia were denied the right to emigrate without paying a tax. but these are not american citizens being victimized by the soviet union, nor are they israelis endangered by the arabs. they are citizens of russia by birth and descent. the american senate is under no obligation to take them into account. the blacks of south africa are often denied not only the right to emigrate to other lands, but even the right of movement from one part of the same country to another, or one section of the same city to another. elaborate pass laws within south africa have been in operation for generations. movements across racial boundaries, either in terms of marriage or even in terms of visits among relatives and friends, have been drastically curtailed with- in south africa. but, just as there is an enormous difference between an ameri- can readiness to commit economic and military resources in defense of the rights of israelis as against a conspicuous lack of similar commitment in defense of black south africans or black &dquo;rhodesians,&dquo; so, too, it is as yet inconceivable that an american senate would threaten strong economic sanctions against south africa on the issue of the right of black people to move around within their own country, let alone emigrate to a distant land. the rights denied to many blacks in south africa are far greater in number and substance than the simple right to emigrate withheld from soviet jews. when american blacks finally attain a level of influence such as that enjoyed today by american jews, the value of that black american enclave for the third world will rise dramatically. this black enclave in the mightiest nation in the world would indeed become a powerful instrument of counterpenetration, valuable not only for black africa but for the third world at large. the imperative of inequality within the third world what emerges from these considerations is the simple proposi- tion that counterpenetration might well be an indispensable mechanism for the ultimate transition from feudo-imperial rela- tionships to mature interdependence. the contradictions of tech- nological imbalance will continue, but the technological and economic superiority enjoyed by the north could still be out- weighed by other strategies pursued by the third world and its enclaves. the contradictions of technological change also continue. saudi arabia is still technologically a backwater in terms of skills, even if it is in the forefront of the production of energy for use in other countries. a mature interdependence would entail a better rela- tionship, based in part on effective mutual vulnerability, between the technologically superior northern hemisphere and the primary producers in the southern hemisphere. if opec collapsed, or were at any rate seriously weakened, what effect would this have on the struggle by the third world for a new international economic order of some kind? is the dis- array within opec the beginning of a much more serious dis- array in the third world as a whole? at least in the short run, and in spite of the new &dquo;price war&dquo; within opec, the dramatic rise in the power of opec since ~ has had a positive impact on the solidarity of the third world. indeed, one of the striking factors on the world scene since then has been the strange paradox of greater economic disparities among third world countries than ever, combined with greater political solidarity among them. until the terms &dquo;developing countries&dquo; and &dquo;poor coun- tries&dquo; were interchangeable. subsequently, however, the concept of &dquo;wealthy underdeveloped countries&dquo; is no longer a contradic- tion. some analysts have even drawn the conclusion that the term &dquo;third world&dquo; is no longer meaningful because of the great dis- parities among its members. this widening economic gap among the members of the group of notwithstanding, there is a sur- prisingly resilient sense of solidarity. it is conceivable that some degree of inequality is a necessary precondition for certain forms of solidarity, however fragile they may be. in discussing the north atlantic treaty organization, altiero spinelli,’ the distinguished italian europeanist, once demonstrated the importance of inequality in a political alliance or a &dquo;military confederation&dquo; (spinelli, : ): nato is not a classical alliance but rather a true military con- federation-an association of states that have decided on a com- mon defense of particular territories, for which purpose they have created representative bodies, as well as various common military services and a common strategy. as with all other confederations which have meant something in history, this one is viable only because it contains one member &dquo;more equal than others&dquo;- indeed, a super-power. spinelli also examined the momentum of the european com- munity in similar terms after world war ii. europe required a central authority which would distribute aid in a way which would promote a balanced recovery of the various countries, ensure that the reconstruction of germany took place in such a way as not to generate mistrust and disagreement between victors and vanquished, and ensure further that military defense and related foreign policies were harmonized. but, argued spinelli ( : - ): europe, founded on the principle of national sovereignties, was originally incapable of undertaking such tasks alone. the ameri- can hegemony, willingly accepted by the european states in the dramatic period after the war, supplied the supranational power which western europe needed but did not possess. spinelli’s thesis is therefore that the relative cohesion of the western world has rested on the simple fact that the united states was &dquo;more equal&dquo; than the others. inequality within the western world was, in his view, a precondition for viable solidarity. the question which arises now is whether or not inequality within the third world as a result of the dramatic rise of affluence among the oil exporters has created at least a temporary founda- tion of solidarity. the leadership of the third world has passed for the time being into the hands of the arab states. in the s and early s the third world was led by india and jawaharlal nehru. there, too, the massive size of india and the stature of nehru implied both inequality between india and the rest of the states that were in existence at the time and the possibility of effec- tive leadership by india. but the absence of adequate resources in india great enough to sustain international influence, combined with the death of nehru, gradually eroded india’s capacity in the face of the dramatic multiplication of third world states in the united nations in the s. for a while, the third world was bereft of leadership-until the arab world captured it in the s. major initiatives toward changing the world economy have in the last few years disproportionately originated in the arab states. the united states, which initially refused to link, for instance, the discussion of oil with a discussion of other raw materials, has more recently retreated from that position. it would have been easy for the oil producers to limit them- selves to a discussion of their own interests with the oil con- sumers. yet countries such as algeria and iraq have been very aware that third world producers of cotton, cocoa, or even copper could not exercise the same leverage on the world economy as could the oil producers. the latter thus saw it as their duty not only to improve their own lot but also to help create a new international economic order at a global level. the effective- ness of the oil weapon is bound to be temporary. oil may get cheaper again as new supplies are discovered or entirely new forms of energy enter the scene. the oil producers have, thus, only a few years in which to consolidate their power. at present the arab states are rising to the challenge. it remains to be seen whether they will maintain their loyalty and commitment to the more disadvantaged members of the third world. iraq and venezuela have actively tried to create a system of collective aid for distribution by opec to the poorer developing countries. to be sure, many of the arab states have continued to prefer bilateral aid. at the meeting of the opec finance ministers in a decision was reached to establish a development fund for the poorer third world countries. it was understood that this collective aid would supplement any bilateral efforts between individual donors and their friends rather than replace them. the proportion of aid from opec countries within the total aid flows of the world is almost bound to increase substantially in the coming years. what all this means is that a dual strategy is evolving, led pri- marily though not exclusively by the muslim members of opec. this dual strategy, first, puts pressure on the industrial countries to redirect the world economic system so as to give greater equity to the poorer southern hemisphere. the second aspect of the opec strategy is to increase its own performance in aiding and facilitating economic development in poorer countries of the third world. the struggle to create a more equitable world economy may well take a long time. but by the end of the twen- tieth century, historians may be able to say that, among the factors which helped democratize the world economy, was the emergence of oil power for a brief period in the last quarter of the century. mature interdependence and the decline of the west the debate in the united states about energy conservation is being followed in the third world with both curiosity and con- cern. this is because there may be a direct clash between resource conservation by the industrialized countries and prospects for social justice for the third world. a sustained attempt by the northern hemisphere (especially north america, western eu- rope, and japan) to reduce its consumption of oil is bound at the same time to mean reduced leverage and influence for the oil producers over the oil consumers. the economic slowdown in the industrialized countries and the strategies of conservation dis- cussed in the west have already resulted in reappraisal by some members of the organization of petroleum exporting countries about future pricing policy. iran’s ambitious developmental plans have also had to be considerably revised as a result of the short- fall in energy production since the revolution. the tone of decision-making within opec has become more circumspect, a little more cautious. yet the opec countries probably have little more than a decade to exert leverage on the industrialized countries in the direction of a more equitable international economic order. a policy of further restraint in consumption by the northern hemisphere would weaken opec leverage even further. the northern hemisphere’s readiness to respond to arguments is often in direct proportion to its own sense of vulnerability. industrial giants that are still hungry for energy and raw materials from less developed countries are more vulnerable than those that have acquired the discipline of restraint and economy. thus, it is important that for at least another generation the northern hemisphere’s appetite for energy and raw materials should remain relatively unabated and that its dependence on the countries which produce those resources will increase. after all, interdependence means mutual need of each other. as the united states continues to increase the proportion of imported oil for domestic consumption, america’s responsiveness to some pressures from her external sources of energy should grow, and the old pattern of relationships between the dominant north and the underdeveloped south might at last be transformed. indeed the world may already be on the verge of that ultimate transition from feudo-imperial interdependence to more mature balance. within the southern hemisphere itself primitive inter- dependence is still struggling to maintain at once a sense of solidarity and a sense of equality among the constitutent parts. as the century moves through its last quarter, primitive inter- dependence within the third world might indeed remain to serve the functions of creating mature interdependence between the third world and the developed states. and with the arrival of that maturity, that fulfillment in human interaction, the link between the problem of equality and tensions of interdependence might at last enter an era of compatibility. note . spinelli was at the time delegate general of the congress of the european people and secretary general of the italian branch of the movement of european federation. reference spinelli, a. ( ) "atlantic pact or european unity." foreign affairs (july): - . ali a. mazrui, d. phil. (oxon), is director of the center for afroamerican and african studies and professor of political science, university of michigan, ann arbor. he is a former vice-president of ipsa, past president of the african studies association of the united states, and vice-president of the international congress of african studies. among his numerous writings, the following are most relevant to this article: a world federation of cultures: an african perspective, ; africa’s international relations, ; the african condition (b.b.c. reith lectures), . his address is center for afroamerican and african studies, university of michigan, monroe, ann arbor, michigan , u.s.a. september , volume , number american association for apli the advancement of science pp science serves its readers as a forum for the presenta- in the tion and discussion of important issues related to the advancement of science, including the presentation of countrles minority or conflicting points of view, rather than by countriespublishing only material on which a consensus has been reached. accordingly, all articles published in sci- need thai ence-including editorials, news and comment, and diseases book reviews-are signed and reflect the individual views of the authors and not official points of view comed e adopted by the aaas or the institutions with which the authors are affiliated. even moi editorial board most of t : william estes, clement l. markert, john increasin r. pierce, bryant w. rossiter, vera c. rubin, advances maxine f. singer, paul e. waggoner, alexander zucker accompa : frederick r. blattner, bernard f. burke, charles l. drake, arthur f. findeis, e. peter prohibitir geiduschek, glynn isaac, milton russell, wil world, n liam p. slichter, john wood interest. publisher william d. carey countrie associate publisher: robert v. ormes philippin editor ology har philip h. abelson fermenta editorial staff insectaassistant managing editor: john e. ringle insecticic production editor: ellen e. murphy photosyn business manager: hans nussbaum news editor: barbara j. culliton and imm news and comment: colin norman (deputy editor), in the william j. broad, luther j. carter, constance holden, eliot marshall, r. jeffrey smith, mar- republic jorie sun, john walsh govemo] european correspondent: david dickson research news: roger lewin (deputy editor), rich- tion. in ard a. kerr, gina kolata, jean l. marx, thomas atath. maugh ii, arthur l. robinson, m. mitchell plantatio waldrop natural gi administrative assistant, news: scherraine mack; editorial assistants, news: fannie groom, cassan- as a sour dra watts power p .senior editors: eleanore butz, mary dorfman, no g ruth kulstad nitrog associate editors: sylvia eberhart, caitilin gor- in the u don, lois schmitt assistant editors: martha collins, stephen fixing ger kepple, edith meyers book reviews: katherine livingston, editor; lin- systems, da heiserman, janet kegg is likely letters: christine gilbert copy editor: isabella bouldin centunes production: nancy hartnagel, john baker; rose leading tvlowery; holly bishop, eleanor warner; bever- ly durham, jean rockwood, leah ryan, sharon the rice a ryanalaarcovers, reprints, and permissions: grayce finger, algae are editor; geraldine crump, corrine harris with rice guide to scientific instruments: richard g. sommer either selassistants to the editors: susan elliott, diane holland rice ir membership recruitment: gwendolyn huddle member and subscription records: ann ragland populatic editorial correspondence: massachu- institute setts ave., nw, washington, d.c. . area code . general editorial office, - ; book reviews, importan - ; guide to scientific instruments, - ; have bee news and comment, - ; reprints and permis- sions, - ; research news, - . cable: ad- salinity e vancesci, washington. for "information for contribu- swamin tors," write to the editorial office or see page xi, a science, june . in yield c business correspondence: area code . membership and subscriptions: - . new reco advertising representatives if and' director: earl j. scherago world neo production manager: gina reilly advertising sales manager: richard l. charles remarkat marketing manager: herbert l. burklund agenc fsales: new york, n.y. : steve hamburger, g y broadway ( - - ); scotch plains, n.j. : green re c. richard callis, unami lane ( - - ); chi- cago, ill. : jack ryan, room , n. yields an michigan ave. 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( - - ). for it atadvertising correspondence: tenth floor, for internat broadway, new york, n.y. . phone: - . t - . science ed biology in developing countries near future, advances in biology will be important to the developed s. however, the impact of advances on some of the less developed s will be even greater. in the developed countries the big unmet ,t will be supplied is for pharmaceuticals effective in combating viral in humans and animals. improvements in medicine will be wel- verywhere, but the people of the less developed countries have ire urgent needs-food, cooking fuel, and other forms of energy. in the world, outside of africa, per capita production offood has been g, but to maintain this trend will require continued efforts and new s. in many countries supplies of firewood are being depleted, nied by soil erosion. costs of oil and fertilizer have become nearly ive and long-term prospects are even worse. thus, around the ews of advances in applied biology has been noted with great research has been discussed, planned, or initiated in many s. priorities differ according to local needs. for example, in the ies,* the national institute of biotechnology and applied microbi- ls accorded priority to research in biofuels; nitrogen fixation; food ition; plant hydrocarbons; antibiotics, vaccines, and microbial des; and biomass production. india has chosen genetic engineering, ithesis, tissue culture, enzyme engineering, alcohol fermentation, unotechnology as priority areas. philippines, imelda romualdez marcos, who is first lady of the minister of human settlements, member of parliament, and or of metropolitan manila, has been active in pushing for reforesta- a book which she edited,t she has written of the potentials of on forestry. she points out that managed forests can outproduce ;rowth by factors of to . she also notes the potentials of biomass rce of glucose for fermentation or as a fuel for small rural electric [ants. ,en fixation by plants is universally regarded as a high-priority goal. jnited states there has been much talk of incorporating nitrogen nes in corn. but at least genes are involved in the nitrogen fixing and success in reaching the goal may be elusive. practical success to come sooner in the rice paddies of southeast asia. indeed, for s the chinese and vietnamese have maintained agronomic practices :o natural fixation of nitrogen. a number of mechanisms exist. in paddy, conditions are favorable to fixation of nitrogen. blue-green one type of nitrogen fixer. another is bacterial flora associated roots. improvements in the capabilities of such organisms through lection or genetic engineering may be feasible. s the principal cereal grain consumed by most of the world's :n. development of new strains at the international rice research (irri) in the philippines during the past two decades has been an it factor in meeting increased needs for food. recently, new strains bn developed that grow well under such adverse soil conditions as and alkalinity. their adoption will increase production. m. s. ithan, the director of irri, suggests that additional improvements can be obtained at his institute by applying both conventional and mbinant dna methods. when advances in biotechnology are achieved that are applicable to eds, mechanisms will exist for their transfer around the world. a ble international framework is in place, financed in part by the for international development. as a result of the stimulus of the evolution, governments are aware of potentials for improving crop id are maintaining indigenous agricultural stations capable of acting rs for technology transfer.-philip h. abelson minathan, paper presented at the workshop on priorities in biotechnology research tional development, national academy of sciences, washington, d.c., to july the energy crisis and the philippine experience, office of media affairs, manila, o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ applied biology in developing countries ph abelson doi: . /science. ( ), . science article tools http://science.sciencemag.org/content/ / / permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the trademark of aaas. is a registeredscienceadvancement of science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for thescience science. no claim to original u.s. government works. copyright © the authors, some rights reserved; exclusive licensee american association for the advancement of o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ rubidium and potassium levels are altered in alzheimer’s disease brain and blood but not in cerebrospinal fluid roberts et al. acta neuropathologica communications ( ) : doi . /s - - - research open access rubidium and potassium levels are altered in alzheimer’s disease brain and blood but not in cerebrospinal fluid blaine r. roberts , *, james d. doecke , , , alan rembach ˆ, l. fernanda yévenes , christopher j. fowler , catriona a. mclean , , , monica lind , irene volitakis , colin l. masters , , ashley i. bush , , dominic j. hare , and the aibl research group abstract loss of intracellular compartmentalization of potassium is a biochemical feature of alzheimer’s disease indicating a loss of membrane integrity and mitochondrial dysfunction. we examined potassium and rubidium (a biological proxy for potassium) in brain tissue, blood fractions and cerebrospinal fluid from alzheimer’s disease and healthy control subjects to investigate the diagnostic potential of these two metal ions. we found that both potassium and rubidium levels were significantly decreased across all intracellular compartments in the alzheimer’s disease brain. serum from over participants in the australian imaging, biomarkers and lifestyle flagship study of ageing (aibl), showed minor changes according to disease state. potassium and rubidium levels in erythrocytes and cerebrospinal fluid were not significantly different according to disease state, and rubidium was slightly decreased in alzheimer’s disease patients compared to healthy controls. our data provides evidence that contrasts the hypothesized disruption of the blood-brain barrier in alzheimer’s disease, with the systemic decrease in cortical potassium and rubidium levels suggesting influx of ions from the blood is minimal and that the observed changes are more likely indicative of an internal energy crisis within the brain. these findings may be the basis for potential diagnostic imaging studies using radioactive potassium and rubidium tracers. introduction mitochondrial dysfunction and impaired energy metabo- lism are features that immediately precede neuronal loss in alzheimer’s disease (ad) [ ]. oxidative stress arising from neurotoxic β-amyloid (aβ) accumulation and oligomerization causes a loss in membrane integrity in the synapse [ ], which is heavily dependent on sufficient atp production to regulate ion transport in and out of the cell [ ]. oligomeric aβ species adversely affect cellular function through a range of hypothesized mechanisms, a number of which directly compromise both energy production and membrane potential [ , ]. impaired energy production related to ad pathology has been of research interest. positron emission tomography * correspondence: blaine.roberts@florey.edu.au ˆdeceased the florey institute of neuroscience, the university of melbourne, parkville, vic, australia cooperative research centre for mental health, parkville, vic, australia full list of author information is available at the end of the article © the author(s). open access this artic international license (http://creativecommons reproduction in any medium, provided you g the creative commons license, and indicate if (http://creativecommons.org/publicdomain/ze (pet) has identified a metabolic decrease in glucose consumption in the ad brain [ ], which is indicative of reduced neural activity [ ] and direct impairment of na+/k+-atpase-regulated intramembrane ion trans- port [ ]. thus, there is potential that markers of modified k+ handling may be indicative of ad, and could be a useful preclinical marker of increased ad risk. as a group alkali metal, rubidium (rb+) has simi- lar biochemical characteristics to k+ [ ]. though it has no known biological function, rb+ is present in almost all biological systems due to its ability to readily exchange with k+ [ ]. assessment of rb+ is a useful proxy for k+, so much so that turnover of radioactive rb+ has been successfully used as a measure of basal metabolic rate [ ]. rubidium assays are also less prone to environmental contamination, and the ion is present in biological matrices at concentrations well suited to contemporary analytical techniques [ ]. le is distributed under the terms of the creative commons attribution . .org/licenses/by/ . /), which permits unrestricted use, distribution, and ive appropriate credit to the original author(s) and the source, provide a link to changes were made. the creative commons public domain dedication waiver ro/ . /) applies to the data made available in this article, unless otherwise stated. http://crossmark.crossref.org/dialog/?doi= . /s - - - &domain=pdf mailto:blaine.roberts@florey.edu.au http://creativecommons.org/licenses/by/ . / http://creativecommons.org/publicdomain/zero/ . / roberts et al. acta neuropathologica communications ( ) : page of as is the case with many other biometals, there are numerous conflicting reports of either changes to [ , ] or stability of [ – ] rb and k levels in ad, most likely due to low statistical power. here, we used post mortem brain tissue from the victorian brain bank network along with blood samples from the australian imaging, biomarkers and lifestyle flagship study of ageing [ ], which is one of the world’s largest longitudinal studies of ad, to investigate changes in the regulation of k+ and rb+ from a system-wide perspective. we aimed to categorically determine if levels of these metals are altered in ad. methods and materials human brain samples all brain tissues were obtained from the victorian brain bank network, and all experiments were approved by the university of melbourne health sciences, human ethics subcommittee (id ). tissue was collected at autopsy, frozen at − °c, then thawed to − °c and sectioned into cm slices. from these, c.a. g samples of frontal cortex were collected and . g aliquots of grey matter dissected and stored at − °c until analysis. neurological control tissues were defined as free from ad lesions with the number of plaque and tangles were well below the cut-off values for the neuropathological diagnosis of ad (nia reagan criteria). no other neuro- logical disease was present. preparation of tissue homogenate fractions sample preparation steps for tissue samples were adapted our previously reported methods [ , ]. aliquots ( . – . g) of dissected grey matter from the frontal cortex were thawed on ice and homogenized in single- use biomasher (omni international) vials. after centri- fugation at , g a : tissue-to-buffer (w/v) ratio of tris buffered saline (tbs; mm tris, ph . , mm nacl) with edta-free protease inhibitors (roche) was added to each homogenate. samples were transferred to ultracentrifuge vials, spun at , g for min at °c, and then had the supernatant removed (the ‘soluble’ frac- tion). the remaining pellet was isolated and resuspended with : (w/v) mm naco (ph . ), then centrifuged again at , g for min at °c to retrieve the ‘vesicular’ fraction. remaining material was then subjected to extraction of membrane-bound proteins and metals (the ‘membrane’ fraction) by addition of : (w/v) m urea, m thiourea, % -[( -cholamidopropyl) dimethylammo- nio]- -propanesulfonate (chaps) and mm bicine (ph . ) and further centrifugation at , g for min at °c. any remaining ‘insoluble’ material was then digested in % formic acid for c.a. h before centrifuga- tion as performed for all other extractions. no material remained at the conclusion of fractionation experiments. preparation of blood samples protocols for the preparation of serum and erythrocytes was followed according to our previously reported method [ ]. whole blood was drawn from aibl subjects after overnight fasting. for serum collection, blood was drawn into serum-gel . ml tubes (sarstedt) and left standing at room temperature for min before centrifugation at g for min. serum was split into μl aliquots and stored in liquid nitrogen until analysis. after thawing, serum samples were spun briefly at g and diluted : in % hno for analysis. platelets were recovered by centrifuging a plasma fraction (collected from whole blood in a lithium-heparin tube) at g for min and re- moving the plasma supernatant. erythrocytes were collected from blood samples taken after an overnight fast into standard lithium-heparin . ml tubes (sarstedt). samples were spun at g to remove plasma and platelets, leaving erythrocytes that were washed three times in . % (w/v) nacl. erythro- cytes were distributed by inverting the tube and then centrifuged at g for min, after which the super- natant was removed and samples were spun again at g for min at room temperature. erythrocytes were then resuspended in ml of . m pbs and stored in liquid nitrogen until analysis. a μl of thawed eryth- rocytes were transferred to . ml polypropylene tubes and digested in equal volumes of % hno and ≥ % h o on a hotplate at °c. after cooling, samples were diluted : with % hno . platelets were prepared for analysis using the same digestion procedure as described for erythrocytes. preparation of csf samples cerebrospinal fluid was collected using the gravity drip method described by rembach et al. [ ]. patients underwent a lumbar puncture procedure following an overnight fast, and up to ml of csf was collected directly into a ml polypropylene tube. samples were centrifuged at g at °c and then divided into μl aliquots and stored on liquid nitrogen. after thawing, μl aliquots were diluted : with % hno for analysis. rubidium and potassium analysis all metal analyses were performed on an agilent × series inductively coupled plasma-mass spectrometer (icp-ms) using a teflon miramist nebulizer (burgener research inc.) and scott-type double-pass spray chamber (glass expansion). helium was used as a collision gas to remove potential polyatomic interferences. the instru- ment was calibrated using multi-element standards (accustandard, icp-ms- - , icp-ms- - , icp-ms- - ; total of elements) containing k and rb at , , , , and μg l− with y introduced online roberts et al. acta neuropathologica communications ( ) : page of through a t-piece as the internal standard. k and rb were monitored. seronorm™ l and l (sero) were reconstituted in : , % hno prior to analysis for use as quality control standards. statistical analysis all statistical testing was performed in graphpad prism v . h using unpaired t-tests, one-way anova and pearson correlation analysis as appropriate. significance was defined as p < . after bonferroni post-hoc testing. results k and rb levels are consistently decreased in fractionated brain homogenates we analyzed post mortem ad and healthy control (hc) frontal cortical tissue (n = per group, matched for age and sex; see table for demographics) by subjecting homogenates of frontal cortex to a stepwise fractionation process that extracted material into ‘soluble’, vesicular- peripheral membrane (‘vesicular’), membrane-bound (‘membrane’) and ‘insoluble’ classifications [ ]. these solutions were then assayed for total k and rb content using inductively coupled plasma-mass spectrometry (icp-ms; see materials and methods). in ad frontal cortex significant decreases in both k and rb levels were apparent (fig. a-b). the degree of change increased in magnitude from the ‘soluble’ to ‘insoluble’ fractions. as expected, a high degree of correlation between tissue k and rb levels were observed regardless of diagnosis (r = . (hc); r = . (ad); both p < . ; fig. c-d). however, the slope measured by linear regression was significantly decreased in the ad brains ( . % of hc; f = . , p < . ). a receiver operating characteristic (roc) curve of both k and rb levels in the total homogenate (which showed the largest difference between clinical classifications) found that rb performed better at predicting ad, with an area under the curve of . versus . for k (both p < . ; fig. e-f). serum levels of k and rb are altered in alzheimer’s disease to investigate whether the observed changes in k and rb levels within brain homogenates are reflected in the table subject demographics for post mortem brain samples healthy controls (n = ) alzheimer’s disease (n = ) p value age (years) . ( . ) . ( . ) . females (%) . . . % apoe ε carriers . . < . post mortem interval (hours) . ( . ) . ( . ) . mean (standard deviation); p-value calculated using a two-tailed student’s t-test periphery, we examined serum k and rb concentrations in the entire baseline aibl cohort, including the mildly cognitively impaired group (ntotal = ; nhc = ; nmci = ; nad = ; table ; see ellis et al. [ ] for cohort full demographics). significant differences were observed for both analytes between hc and ad groups, but these shifts did not reflect the magnitude or direc- tion of those observed in the brain. there was a . % increase in serum k levels in the ad subjects (fig. a), with a small ( . %) decrease in serum rb (fig. b). there was a highly significant (p < . ) decrease in the ratio of rb to k in the ad group (fig. c), though roc analysis revealed changes in all three measures were less robust (though still statistically significant) indicators of ad than total rb and k in brain homogenates (auck = . ; aucrb = . ; aucrb:k = . ; additional file : figure s ). k and rb levels correlated in both groups, although again to a much lesser extent than in brain homogenates, and the slopes of both lines did not differ (f = . ; p = . ; fig. d). rb levels are decreased in platelets, but not erythrocytes or csf we analyzed a subset of ad and hc erythrocytes for rb and k concentrations (n = per classification) and found no significant difference between groups (p = . ; fig. e, f). k levels in a subset of hc, ad and mci platelets (nhc = , nad = , nmci = ; table ) were not different between groups (fig. a). rb levels in ad plate- lets were significantly decreased compared to the hc group (one-way anova; p < . ; fig. b; table ). this decrease in rb levels in platelets showed limited diag- nostic potential when examined using an roc curve (additional file : figure s ). in cerebrospinal fluid (csf; nhc = , nad = , nmci = ; table ) k and rb levels were unaltered according to clinical classification (fig. c, d). discussion our results expand upon a previous smaller study that reported decreased rb levels in the ad brain [ ]; we found here that rb levels are decreased in interstitial/ cytosolic, vesicular, membrane-bound and otherwise insoluble fractions, and that these changes correlate with and reflect decreased k levels in the same isolates. both k and rb levels have been shown to be decreased in homogenates from a range of brain regions that show progressive neurodegeneration in ad [ ]. we found no compelling evidence that k and rb levels external to the brain (i.e., blood products and csf) have diagnostic potential in ad research. our data suggests that the observed effects of impaired alkali metal metabolism in the ad brain, such as altered na+/k+-atpase activity manifest as a decrease in fig. a, b k and rb levels in fractionated brain homogenates were consistently decreased in ad brains (n = per group; one-way anova; ** p < . ; *** p < . ; percentage decrease in ad group compared to healthy controls shown). error bars represent the standard error of the mean. c both metals showed significant correlation regardless of clinical classification (p < . ), though the slope of the line of best fit was significantly decreased in the ad group (p < . ). d, e both metals performed well at predicting ad via roc curve analysis, with rb slightly superior performance roberts et al. acta neuropathologica communications ( ) : page of total brain rb and k levels, as opposed to being restricted to a specific fraction. we found that the decrease was of a higher magnitude (c.a. %) within cellular membranes (i.e., the ‘membrane’ and ‘insoluble’ fractions). it is unclear as to whether a reduction in k (and, by nature of its ability to exchange, rb) is a cause or effect of the disease process, though a number of genes associated with k transport and flux have been identified as showing decreased table subject demographics of the baseline aibl cohort used for serum k and rb analysis healthy controls (n = ) mild cognitive impairment (n = ) alzheimer’s disease (n = ) p-value age (years) . ( ) . ( . ) . ( . ) < . females (%) . . . . % apoe ε carriers . . . < . cdr sob . ( . ) . ( . ) . ( . ) < . mmse . ( . ) . ( . ) . ( . ) < . cdr sob is the clinical dementia rating scale sum of boxes score used to stage dementia. mmse is the mini-mental state examination questionnaire score. p-value calculated using a one-way anova or chi-squared test for percentages transcription levels in the ad brain [ ]. in vitro studies of mixed cortical cultures have shown that aβ induces k+ efflux via enhancing the delayed rectifier k+ current ik [ ], potentially through the formation of transient ion channels in bilayer membranes [ ]. importantly, this disruption of cellular metabolism in ad likely commences well before the appearance of histopathological features and the onset of clinical symp- toms. genome-wide transcriptomic analysis of ad brains identified as many as % of genes encoding subunits of the mitochondrial electron transport chain were expressed at lower levels in regions of the brain most affected by ad when compared to controls [ ]. neural network analysis of ‘seed genes’ (the principal genes from which regulatory pathways are grown [ ]) identified those encoding the master energy regulator amp-activated protein kinase as being dysregulated in ad [ ]. the effects of impaired energy metabolism appear to primarily result in a loss of membrane integrity through its negative impact on active transport mechanisms that regulate resting membrane potential. as the major consumer of energy in the cell—maintaining resting potential and action potentials accounts for – % of energy use in neurons in the cortex [ ]—the action of fig. k levels were significantly increased in ad serum (a; one-way anova; * p < . ), whilst rb levels were conversely decreased in ad (b; * p < . ); the latter mirroring our observation in brain homogenates. the ratio of rb to k was significantly (*** p < . ) decreased in ad (c), though rb and k levels were less well correlated in serum (d). in a subset (n = per group) of erythrocytes from hc and ad groups, there was no significance difference in metal concentration (e, f). boxes depict th and th percentiles and mean; error bars represent minimum to maximum values roberts et al. acta neuropathologica communications ( ) : page of na+/k+-atpase is easily compromised by energy deficits. in the ad brain, na+/k+-atpase activity is depressed [ ], with a reduction in α subunit mrna observed, a process that occurs prior to the formation of aβ plaques and is rapidly accelerated in the disease [ ], further supporting the hypothesis that an energy table subject demographics for erythrocytes healthy controls (n = ) alzheimer’s disease (n = ) p-value age (years) . ( . ) . ( . ) . females (%) . . . % apoe ε carriers . . . p-value calculated using a two-tailed student’s t-test crisis is inexorably linked to the molecular basis of the disease. these findings may have diagnostic potential in the clinical setting. rubidium- has been extensively used in positron emission tomography (pet) as a diagnostic marker for brain tumors [ ], with increased uptake of the rb- tracer indicative of a loss of blood-brain barrier (bbb) integrity. permeability of the bbb is thought to be a feature of both normal aging and ad [ ], though both in- creased serum k concentrations in ad and a failure to identify a change in csf k or rb levels tends to suggest that bbb permeability is not directly responsible for the decrease in akali metal levels in the ad brain. further, a recent study using animal models of ad, including the lipopolysaccharide (lps) model of induced inflammation, table subject demographics for platelets healthy controls (n = ) mild cognitive impairment (n = ) alzheimer’s disease (n = ) p-value age (years) . ( . ) . ( . ) . ( . ) < . females (%) . . < . % apoe ε carriers . . < . p-value calculated using a one-way anova or chi-squared test for percentages table subject demographics for csf healthy controls (n = ) mild cognitive impairment (n = ) alzheimer’s disease (n = ) p-value age (years) . ( . ) . ( . ) . ( . ) . females (%) . . . . % apoe ε carriers . . p-value calculated using a one-way anova or chi squared test for percentages fig. k and rb levels in platelets and csf. a, b in platelets no significant changes were observed for k, though rb was significantly decreased (p < . ; one-way anova) in ad subjects compared to controls. c, d k and rb levels in csf remained unchanged. boxes depict th and th percentiles and mean; error bars represent minimum to maximum values roberts et al. acta neuropathologica communications ( ) : page of ps -app and human tau expressing transgenic mice lines, apoe knockout and apoe knock-in mice showed no evidence of bbb permeability compared to both wild type and a positive multiple sclerosis model control using multiple assays, including rb- radiotracer experiments [ ], questioning the long-held belief that bbb disruption is characteristic of ad. receiver-operating characteristic curve analysis of brain rb levels (fig. f) shows that changes in levels of this metal is a strong predictor of ad, therefore rubidium- / pet imaging could be used to identify early-stage ad. considering that alkali metal homeostasis is disrupted via decreased na+/k+-atpase activity prior to aβ plaque for- mation, this approach may have greater preclinical value than the contemporary method employing pittsburgh compound-b to assess brain amyloid burden by pet [ ]. however, if the bbb integrity is maintained in ad, delivery of the imaging agent presents a challenge to use as a preclinical diagnostic tool. an intact bbb still demon- strates a small degree ( . %) of rb uptake, though this is ten-fold less than typically observed in cases of brain tu- mors and associated bbb disruption [ ]. hyperosmolar bbb disruption via injection of % mannitol to the carotid artery has been shown to induce a temporary window for rb loading into the baboon brain [ ], though the safety of this approach in humans remains untested beyond patients with pre-existing brain tumors. a non-invasive scanning ultrasound approach to tempor- arily open the bbb in the app transgenic ad mouse model was shown to be effective in clearing accumulated aβ [ ], and a number of clinical trials testing the safety and efficacy of this approach, predominantly for drug delivery, are currently ongoing [ ]. development of a suitable bbb-permeable vehicle that releases rb into the brain is an intriguing line of enquiry. an alternative means to monitor brain rb levels without the need to deliver an exogenous tracer uses the paramagnetic properties of the naturally occurring rb radioisotope, which accounts for approximately % of rb in the natural environment. t and t relaxation times are well suited to magnetic resonance imaging using specialized coils, and this approach has been used to quantitatively assess k (using rb as a proxy) in the brains of ischemic rats [ , ]. this approach uses roberts et al. acta neuropathologica communications ( ) : page of chronic rb loading via drinking water in the weeks preceding mri scanning, which could be employed in a diagnostic workflow for ad, though the use of high field strength (e.g., t) mri systems may have the capacity to assess endogenous rb with sufficient sensitivity. conclusions we have shown that rb and k levels are consistently de- creased across all cellular components in the ad frontal cortex, and altered to a lesser extent in the periphery. as rb is readily exchangeable with k, we hypothesize that this decrease is indicative of dysfunctional na+/k+-atpase activity, a pathological feature of ad that is representative of an internal energy crisis and precedes the formation of proteinaceous inclusions and neuron loss in the disease. rubidium levels in the brain performed well in predicating ad, and may represent a new avenue of early diagnosis using existing in vivo imaging techniques, including pet and mri. additional file additional file : roc analysis of rb & k levels in plasma (figure s ) and platelets (figure s ). (docx kb) acknowledgements we wish to acknowledge the support of the cooperative research centre (crc) for mental health. the crc programme is an australian government initiative. tissues were received from the victorian brain bank network, supported by the university of melbourne, alfred hospital, the victorian forensic institute of medicine, the national health and medical research council. we acknowledge funding from the victorian government’s operational infrastructure support program and the australian research council linkage projects scheme (with agilent technologies). partial support from the national health and medical research council and the alzheimer’s drug discovery research foundation. authors’ contributions br conceived of the study, and participated in its design and coordination. dh, br, ab wrote the paper. ir, dh, lyf, br carried out metal measurements. clm, ab, cf, ar participated in the collection of aibl samples. cam participated in the collection and diagnosis of brain tissue. br, dh, jd, lyf, cf participated in the study design and statistical analysis. ml, dh, br, lyf, ir carried out sample preparation. all authors read and approved the final manuscript. competing interests the authors declare that they have no competing interests. author details the florey institute of neuroscience, the university of melbourne, parkville, vic, australia. cooperative research centre for mental health, parkville, vic, australia. the australian e-health research centre, herston, qld, australia. csiro preventative health flagship, molecular science and engineering, parkville, vic, australia. department of anatomical pathology, the alfred hospital, melbourne, vic, australia. department of medicine, central clinical school, monash university, clayton, vic, australia. elemental bio-imaging facility, university of technology, broadway, sydney, nsw, australia. https:// aibl.csiro.au/about/aibl-research-team. received: september accepted: october references . mattson mp. pathways towards and away from alzheimer’s disease. nature. ; 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doecke, jd; rembach, a; yevenes, lf; fowler, cj; mclean, ca; lind, m; volitakis, i; masters, cl; bush, ai; hare, dj title: rubidium and potassium levels are altered in alzheimer's disease brain and blood but not in cerebrospinal fluid date: - - citation: roberts, b. r., doecke, j. d., rembach, a., yevenes, l. f., fowler, c. j., mclean, c. a., lind, m., volitakis, i., masters, c. l., bush, a. i. & hare, d. j. ( ). rubidium and potassium levels are altered in alzheimer's disease brain and blood but not in cerebrospinal fluid. acta neuropathologica communications, ( ), https://doi.org/ . /s - - - . persistent link: http://hdl.handle.net/ / file description: published version license: cc by 	abstract 	introduction 	methods and materials 	human brain samples 	preparation of tissue homogenate fractions 	preparation of blood samples 	preparation of csf samples 	rubidium and potassium analysis 	statistical analysis 	results 	k and rb levels are consistently decreased in fractionated brain homogenates 	serum levels of k and rb are altered in �alzheimer’s disease 	rb levels are decreased in platelets, but not erythrocytes or csf 	discussion 	conclusions 	additional file 	acknowledgements 	authors’ contributions 	competing interests 	author details 	references parp- and cytokine-mediated β-cell damage: a nick in the okamoto model? parp- and cytokine-mediated �-cell damage: a nick in the okamoto model? nadia cobo-vuilleumier and benoit r. gauthier pancreatic islet development and regeneration unit, department of stem cells, cabimer-andalusian center for molecular biology and regenerative medicine, seville, spain submitted may ; accepted in final form may type diabetes mellitus (t dm), a complex genetic disease characterized by the destruction of pancreatic islet �-cells, leads to insulin deficiency and, ultimately, hyperglycemia in inflicted individuals. the etiology stems from a progressive autoimmune assault, in which macrophages and t cells secrete proinflammatory cytokines, such as il- �, ifn-�, and tnf-�, as well as nitric oxide (no), which provoke �-cell death. the latter situation is further aggravated, as remaining �-cells produce chemokines, thereby attracting more immune cells and, thus, escalating the inflammatory process. cytokine-me- diated cell death proceeds through necrosis or apoptosis and implicates the activation of the jak/stat and nf-�b signaling pathways ( ). a common downstream target gene of these pathways is inducible no synthase (inos), which generates no, a major effector of �-cell death along with reactive oxygen species. historically, t dm has been recapitulated in rodents with use of diabetogenic agents, such as streptozotocin (stz) and alloxan, to destroy the �-cell mass. in particular, stz is distinctly taken up by �-cells, inducing dna alkylation and leading to impaired �-cell function and death. in addition, stz was also found to generate no species, further deteriorating �-cell survival ( ). more than years ago, okamoto and colleagues ( ) demonstrated that stz and alloxan cause cell death by inducing dna strand breaks and the activation of poly(adp)-ribose synthase. this enzyme, also known as poly- (adp)-ribose polymerase- (parp- ), is activated by dna breaks and uses nad� to covalently link units of adp ribose, thereby forming long polymers on nuclear acceptor proteins such as histones. this has been suggested to diminish their affinity for dna, opening the site of dna damage and allowing access to the base excision repair machinery ( ). despite this important role in signaling and facilitating dna repair, the split functional personality of parp- as mr. hyde and dr. jeckyll is revealed when parp- is hyperactivated. indeed, in an attempt to replenish the nad� pool that is being drained by the parp- , the cellular atp stores are rapidly exhausted, resulting in energy crisis-induced necrosis. the latter forms the basis of the “okamoto model,” which provides a unifying hypothesis on how hyperactivation of parp- leads to impaired �-cell function (insulin biosynthesis and secretion) and, ultimately, death in response to chemical insults ( , ). in agreement with this model, several independent studies have shown that mice lacking parp- were resistant to stz- mediated �-cell death and to development of hyperglycemia ( , , ). in parallel, parp- -deficient mice were found to be extremely resistant to lps-induced endotoxic shock as a con- sequence of a blunted nf-�b-dependent transcription, leading to inhibition of inos, as well as tnf-� and ifn-�, expression in macrophages ( ). thus, parp- not only mediates the cytotoxic effect of no, but it also appears to stimulate inflam- mation by regulating the nf-�b signal transduction pathway. these compelling data led to a large randomized double- blind, placebo-controlled trial in which pre-t dm participants recruited from european countries, as well as the united states and canada, were given the parp- inhibitor nicotin- amide or a placebo. after five years of treatment, the incidence of developing t dm was identical in both groups ( ). these studies highlight the complexity of t dm and the pitfalls in translating lessons learned in animal models of diabetes to human physiology. indeed, one critical question arises: how well does the stz-induced �-cell death model mimic t dm? in fact, hyperactivation of parp- by stz results in �-cell death through necrosis, while �-cell destruction in t dm predominantly proceeds through a cytokine-mediated apopto- sis process. interestingly, parp- is cleaved and inactivated by caspase- and - in the early phase of apoptosis, suggesting that parp- does not participate in this mode of cell death ( ). furthermore, heller et al. ( ), as early as , demonstrated that islets isolated from parp- -deficient mice were as sensi- tive as control islets to cell lysis by high concentrations of no and reactive oxygen species. these data clearly raise serious doubts about the importance of parp- as a key actor in �-cell destruction in a setting of t dm. thus, although the role of parp- in �-cell destruction via necrosis has been irrefutably associated with stz and in establishing the validity of the okamoto model, its role in cytokine-mediated cell death re- mains to be fully explored. in this issue of the journal, andreone et al. ( ) address this gap and challenge the okamoto model by demonstrating that parp- does not participate in the deleterious effect of cyto- kines on islet function and, potentially, survival. indeed, an- dreone et al. demonstrate that, similar to control islets, parp- -deficient islet cells exposed to the proinflammatory cytokines il- and ifn-� exhibit normal activation of the nf-�b sig- naling pathway, which leads to induction of inos expression and production of no. furthermore, deletion of parp- did not alter il- /ifn-�-mediated phosphorylation of stat- , indi- cating that the jak/stat signaling pathway implicated in apo- ptosis is activated by cytokines in parp- -deficient islets ( ). using a biochemical assay that measures uptake of a neutral red dye within acidic lysosomes, andreone et al. show that islets lacking parp- are resistant to cytokine-mediated cyto- toxicity, whereas they remain sensitive to the general apoptotic agent staurosporine. as lysosome acidification is an atp- dependent process, which may be preserved in parp- -defi- cient islets due to sustained levels of atp, andreone et al. astutely used the terminal deoxynucleotidyl transferase-medi- address for reprint requests and other correspondence: b. r. gauthier, pancreatic islet development and regeneration unit, dept. of stem cells, cabimer-andalusian center for molecular biology and regenerative med- icine, avda américo vespucio, parque científico y tecnológico cartuja , seville, spain (e-mail: benoit.gauthier@cabimer.es). am j physiol endocrinol metab : e –e , ; doi: . /ajpendo. . .editorial focus - / copyright © the american physiological society http://www.ajpendo.orge downloaded from journals.physiology.org/journal/ajpendo at carnegie mellon univ ( . . . ) on april , . ated dutp nick-end labeling (tunel) assay as an alternative approach to evaluate cell death. the tunel assay is particu- larly useful, as it reveals dna strand breaks, which are a hallmark of no-mediated cell death. consistent with preserved no production, parp- -deficient islets exhibited increased tunel-positive cells in the presence of cytokines to levels similar to those of treated control islets. consequently, glu- cose-induced insulin secretion was also impaired in parp- - lacking islets treated with cytokine. as development of t dm results from an intricate cross talk between immune cells and islets, andreone et al. also assessed whether inflammatory cell signaling was impaired in macrophages derived from parp- deficient mice, as previously reported by others ( ). surpris- ingly, the nf-�b signaling pathway, as well as downstream inos activation and no production, were unaltered in mac- rophages derived from parp- knockout mice that were ex- posed to cytokines or lps. a potential explanation for discrep- ancies in results may stem from the fact that previous studies were performed with macrophages exposed in vivo to lps ( ), while andreone et al. studied naïve macrophages treated in vitro with the endotoxin. the work by andreone et al. ( ) demonstrates that, in contrast to stz-mediated cell death and the okamoto model, parp- does not contribute to cytokine-induced �-cell dam- age. furthermore, parp- does not appear to be implicated in the signaling of the inflammatory response by macrophages. these results are consistent with the clinical trial demonstrat- ing that nicotinamide does not improve onset of t dm, caus- ing a serious “nick” in the okamoto model. nonetheless, one question remains to be clearly resolved from the study of andreone et al.: does parp- deficiency prevent, beyond doubt, islet cell death? indeed, dna damage was increased in islets from stz-treated parp- -deficient mice, yet these ani- mals did not develop hyperglycemia, and islet integrity and function were preserved ( ). it is tempting to speculate that parp- , which accounts for � % of all parp activity in mammalian cells ( ), may provide sufficient residual activity to repair stz-mediated dna damage in parp- knockout mice, thereby avoiding �-cell death and development of hyperglyce- mia. in this context, it is interesting to note that parp- was recently shown to be essential for �-cell function and expan- sion in response to a high-fat diet ( ). unfortunately, the long-term effect of cytokines on �-cell dna damage and insulin secretion was not addressed by andreone et al., as all experiments were performed within h of treatment. a key study that could resolve whether parp- deficiency is an asset in protecting �-cells against a continuous exposure to proin- flammatory cytokines would involve breeding of parp- - deficient mice to animal models of experimental autoimmune diabetes. this approach could also offer a valuable tool to highlight and resolve potential pitfalls associated with the failure of parp- inhibitors to delay or prevent onset of t dm in human subjects. nonetheless, recent findings dem- onstrating the importance of parp- in �-cell function, com- bined with the apparent redundancy of parp- in cytokine- mediated �-cell dysfunction, strongly argue against the use of new and more specific parp inhibitors such as olaparib as novel therapies for the treatment of t dm. acknowledgments we thank dr. felipe cortés ledesma for critical reading of the manuscript. grants financial support for this study was provided by the consejeria de salud, junta de andalucia, the spanish ministry of science and innovation, instituto de salud carlos iii, and cofunded by fondos feder and the fundacion publica andaluza progreso y salud. disclosures no conflicts of interest, financial or otherwise, are declared by the authors. author contributions n.c.-v. and b.r.g. drafted the manuscript; n.c.-v. and b.r.g. edited and revised the manuscript; n.c.-v. and b.r.g. approved the final version of the manuscript. references . andreone t, meares gp, hughes kj, hansen pa, corbett ja. cytokine-mediated �-cell damage in parp- -deficient islets. am j physiol endocrinol metab (first published april ). doi: . /ajpendo. . . . bai p, canto c, brunyanszki a, huber a, szanto m, cen y, yamamoto h, houten sm, kiss b, oudart h, gergely p, menissier-de murcia j, schreiber v, sauve aa, auwerx j. parp- regulates sirt expression and whole-body energy expenditure. cell metab : – , . . burkart v, wang zq, radons j, heller b, herceg z, stingl l, wagner ef, kolb h. mice lacking the poly(adp-ribose) polymerase gene are resistant to pancreatic beta-cell destruction and diabetes development induced by streptozocin. nat med : – , . . eizirik dl, mandrup-poulsen t. a choice of death—the signal-trans- duction of immune-mediated beta-cell apoptosis. diabetologia : – , . . gale ea, bingley pj, emmett cl, collier t. european nicotinamide diabetes intervention trial (endit): a randomised controlled trial of intervention before the onset of type diabetes. lancet : – , . . heller b, wang zq, wagner ef, radons j, burkle a, fehsel k, burkart v, kolb h. inactivation of the poly(adp-ribose) polymerase gene affects oxygen radical and nitric oxide toxicity in islet cells. j biol chem : – , . . lenzen s. the mechanisms of alloxan- and streptozotocin-induced dia- betes. diabetologia : – , . . luo x, kraus wl. on par with parp: cellular stress signaling through poly(adp-ribose) and parp- . genes dev : – , . . masutani m, suzuki h, kamada n, watanabe m, ueda o, nozaki t, jishage k, watanabe t, sugimoto t, nakagama h, ochiya t, sug- imura t. poly(adp-ribose) polymerase gene disruption conferred mice resistant to streptozotocin-induced diabetes. proc natl acad sci usa : – , . . oliver fj, menissier-de murcia j, nacci c, decker p, andriantsito- haina r, muller s, de la rubia g, stoclet jc, de murcia g. resistance to endotoxic shock as a consequence of defective nf-�b activation in poly(adp-ribose) polymerase- deficient mice. embo j : – , . . pieper aa, brat dj, krug dk, watkins cc, gupta a, blackshaw s, verma a, wang zq, snyder sh. poly(adp-ribose) polymerase-defi- cient mice are protected from streptozotocin-induced diabetes. proc natl acad sci usa : – , . . yamamoto h, uchigata y, okamoto h. dna strand breaks in pancre- atic islets by in vivo administration of alloxan or streptozotocin. biochem biophys res commun : – , . . yamamoto h, uchigata y, okamoto h. streptozotocin and alloxan induce dna strand breaks and poly(adp-ribose) synthetase in pancreatic islets. nature : – , . editorial focus e parp- and cytokine-mediated �-cell death ajp-endocrinol metab • doi: . /ajpendo. . • www.ajpendo.org downloaded from journals.physiology.org/journal/ajpendo at carnegie mellon univ ( . . . ) on april , . http://dx.doi.org/ . /ajpendo. . experimental study of single screw expander used in low-medium temperature geothermal power system energy procedia ( ) – available online at www.sciencedirect.com sciencedirect - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of icae doi: . /j.egypro. . . the th international conference on applied energy – icae experimental study of single screw expander used in low- medium temperature geothermal power system jingfu wanga,b,*, xinxin zhanga,b, yongzhi zhanga,b, yong zhanga,b, wei wanga,b akey laboratory of enhanced heat transfer and energy conservation, ministry of education, college of environmental and energy engineering,beijing university of technology, beijing , pr china bkey laboratory of heat transfer and energy conversion, beijing municipality, college of environmental and energy engineering,beijing university of technology, beijing , pr china abstract research and development of renewable energy is one solution to energy crisis and its related environmental problem. among all kinds of renewable energy, geothermal energy has good development feasibility due to its low investment and operation costs, independence to weather and climate change, and stable power generation. in china, high- temperature geothermal resource is rare; however, low-medium temperature geothermal resource is widely distributed. therefore, small and medium sized geothermal power system based on low-medium temperature organic rankine cycle(orc) is a good choice for geothermal exploitation. expander is the key device in such system. single screw expander has proper size and good output performance. therefore, in order to test the application of single screw expander in geothermal exploitation, compressed air was used as working fluid to conduct experimental study at different temperature. the results show that at the same rotational speed, the single screw expander at a higher air temperature has a bigger output power, a smaller gas consumption rate, a bigger expansion ratio, a bigger temperature drop, a higher thermal efficiency, and a smaller irreversible loss. moreover, if a lubricant circle is added in the experimental system, the single screw expander with lubricant at a lower air temperature will have the same performance as the expander without lubricant at a higher air temperature. therefore, the performance of single screw expander can be improved by adding a lubricant circle and raising compressed air temperature. © the authors. published by elsevier ltd. selection and/or peer-review under responsibility of icae keywords: single screw expander; geothermal power generation; organic rankine cycle; compressed air; lubricant circle * corresponding author. tel.: + - - - ; fax: + - - - . e-mail address: jfwang@bjut.edu.cn . © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of icae http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf jingfu wang et al. / energy procedia ( ) – . introduction with industrial development in recent years, a lot of problems caused by energy consumption are become more and more serious. therefore, development and utilization of new energy and renewable energy is great significance. among all kinds of renewable energy, geothermal energy has an average capacity factor of % and capacity factors up to % are considered possible[ ]. moreover, geothermal energy has good development feasibility due to its low investment and operation costs, independence to weather and climate change, and stable power generation. in china, high-temperature geothermal resource is rare; however, low-medium temperature geothermal resource is widely distributed. therefore, small and medium sized geothermal power system based on low-medium temperature organic rankine cycle(orc) is a good choice for geothermal exploitation. expander is the key device in such system. the rapid development of compressor technology makes a possible breakthrough in the manufacture of small size expander. single screw technology has many advantages such as a good force balance, a long life, a high pressure ratio, a high volumetric efficiency, a high efficiency at part load, a simple structure, a low noise, and so on. therefore, single screw expander becomes a promising technology in small size expander. in this paper in order to test the application of single screw expander in geothermal exploitation, compressed air was used as working fluid to conduct experimental study at different temperature. . establishment of experimental system the single screw expander used in experimental system was developed and manufactured by the lab where the authors work. some previous research work has been conducted on single screw expander by the members in author’s research team[ - ]. in this study, expander inlet flow is . nm /min and power output is kw. fig depicts the single screw expander experimental system with heated compressed air as the working fluid. the main device consists of a single screw expander, a compressed air heating system, a lubricant system, a data acquisition system, and a dynamometer machine. fig. . single screw expander experimental system . experimental result and discussion due to the length limitation of paper, only the performances of single screw expander with and without lubricant when inlet temperature is are reported. fig to fig depict the relation between the jingfu wang et al. / energy procedia ( ) – performances of single screw expander and its rotational speed. theses performances includes power, gas consumption rate, expansion ratio, temperature drop, thermal efficiency, and irreversible loss. fig. . relation between power and rotational speed fig. . relation between gas consumption rate and rotational speed fig. . relation between expansion ratio and rotational speed fig. . relation between temperature drop and rotational speed fig. . relation between thermal efficiency and rotational speed fig. . relation between irreversible loss and rotational speed jingfu wang et al. / energy procedia ( ) – from the above figures, it can be seen that because of the sealing and lubricating of lubricant, at the same rotational speed, the single screw expander with lubricant has a bigger power output. at the same rotational speed, the single screw expander with lubricant has a smaller gas consumption rate. the expansion ratio of expander decreases with the increase of rotational speed. the expander with lubricant has a bigger expansion ratio at the same rotational speed. at the same rotational speed, the expander with lubricant has a bigger temperature drop. at the same rotational speed, the expander with lubricant has a bigger thermal efficiency, but the efficiency increase is not very significant. at the same rotational speed, the expander with lubricant has a smaller irreversible loss. . conclusion in order to test the application of single screw expander in geothermal exploitation, compressed air was used as working fluid to conduct experimental study at different temperature. the results show that at the same rotational speed, the single screw expander at a higher air temperature has a bigger output power, a smaller gas consumption rate, a bigger expansion ratio, a bigger temperature drop, a higher thermal efficiency, and a smaller irreversible loss. moreover, if a lubricant circle is added in the experimental system, the single screw expander with lubricant at a lower air temperature will have the same performance as the expander without lubricant at a higher air temperature. therefore, the performance of single screw expander can be improved by adding a lubricant circle and raising compressed air temperature. acknowledgements this work was supported by the national key basic research program of china ( program, no. cb ). the authors gratefully acknowledge them for financial support of this work. references [ ] lenzen m. current state of development of electricity generating technologies: a literature review. energies , : - . [ ] lu yw, he w, wu yt, ji wn, ma cf, guo h. performance study on compressed air refrigeration system based on single screw expander. energy , : - . [ ] wang w, wu yt, ma cf, xia gd, wang jf. experimental study on the performance of single screw expanders by gap adjustment. energy , : - . biography prof. jingfu wang got this doctor degree from tohoku university, japan. now he works in beijing university of technology and his research interest is utilization technology of renewable energy and basic theory of combustion and pollution control mechanism. microsoft word - -p -editorial editorial j. cent. south univ. ( ) : − doi: https://doi.org/ . /s - - - preface to the special issue on energy storage and conversion wang hai-yan(王海燕) , lu zhou-guang(卢周广) . school of chemistry and chemical engineering, central south university, changsha , china; . department of materials science and engineering, southern university of science and technology, shenzhen , china © central south university press and springer-verlag gmbh germany, part of springer nature energy crisis and environmental pollution owing to the rapid consume of fossil fuel have become the two major challenges faced by human beings. using the new energy, such as solar and wind energy to replace the fossil fuel, is a promising strategy to address the above issues. however, how to implement such new energy is still a big challenge. developing chemical energy storage and conversion devices with high performance, low cost, long lifespan and high safety for wide applications has attracted tremendous attentions. the energy storage devices candidates include li-ion batteries, li-s batteries, na-ion batteries, fuel cell, redox flow batteries and etc. in recent years, significant progresses have been made spanning from the fundamental studies to application-oriented prototypes in the field of energy storage and conversion. for this reason, we organize this special issue on “energy storage and conversion” in journal of central south university to show the latest advances in this field. this special issue collects contributions, including review and articles. the topics cover different aspects in li-ion batteries, na-ion batteries, fuel cells, all-vanadium redox battery, li-s battery and so on. among these contributions, there are papers focusing on the cathode materials (sodium vanadate nanowire, na fepo f/c, li fesio /c/ag, anthraquinone) and anode materials (ce sn o nanocubes, sb@sb o /reduced graphene oxide composite, manganese oxides, spherical tremella- like sb o , anatase tio ) for li-ion batteries. some emerging works on post li-ion batteries are also covered. a na . mno nanorods/graphene composite was synthesized by liu li et al as a high performance cathode material for na-ion batteries. liu yan-yan et al reported a bio-derived n-doped porous carbon as sulfur hosts for high performance lithium sulfur batteries. three papers on electrochemical catalysis are also involved. in the review, zhuang shu-xin reviewed the recent advances of the preparation and applications of perovskite-type oxides for electrocatalysis in oxygen/air electrodes. tang you-gen and coworkers reported a red-blood-cell- like nitrogen-doped porous carbon as a highly efficient metal-free catalyst for oxygen reduction reaction. liu min and coworkers developed hierarchical tio nanorods with a highly active surface for photocatalytic co reduction. in addition, chen yun-gui et al provided an anodic oxidation method to improve the electrochemical properties of carbon paper as negative electrode for vanadium redox battery. and liu fang et al proposed a soc estimation strategy based on data driven ekf algorithm for power battery of ev and phev. in summary, these contributions present the cutting-edge researches in the field of energy storage and conversion. we would like to sincerely thank all the authors for their great efforts in preparing high-quality manuscripts. we also thank the professional editorial office of journal of central south university for their hard-works to make this issue such a great success. guest editors wang hai-yan dr. wang hai-yan earned his b.s ( ), m.s ( ) and ph.d. ( ) degrees in chemistry j. cent. south univ. ( ) : − at central south university. in , he once joined prof. peter g bruce's group in university of st. andrews (uk) as a visiting ph.d. student. starting at , he joined prof. minhua shao's group at hong kong university of science and technology as a hong kong scholar. now he is an associate professor in school of chemistry and chemical engineering at central south university. his current research interests are focused mainly on the new energy materials and devices, including aqueous/non-aqueous li (na) ion batteries and metal-air batteries. he has published over refereed papers with him as the first or corresponding author, including energy & environmental science, advanced materials, advanced energy materials, nano energy, applied catalysis b: environmental, energy storage materials, j. mater chem a (over citation times, h-index , so far). he is a principal inventor of chinese patents. he is the vice director of hunan provincial key laboratory of chemical power sources. lu zhou-guang dr. lu zhou-guang is currently professor in the department of materials science and engineering, southern university of science and technology (sustech), china. he obtained his b.s. and m.s. from the central south university in and , respectively, and phd from the city university of hong kong in . he is the recipient of fellow of royal society of chemistry (frsc), fulbright scholarship of usa government of ― and the overseas high-caliber personnel (level b) of shenzhen government in . his research mainly covers the design and synthesis of nanostructures and their application in lithium/sodium ion batteries, and metal-air batteries. he has authored for more than peer-review journal papers with total citations of more than and h-index of . lu zhou-guang (phd, professor; tel: + - - ; e-mail: luzg@sustc.edu.cn; orcid: - - - ) wang hai-yan (phd, associate professor; tel: + - - ; e-mail: wanghy @ .com; orcid: - - - ; qq: ; wechat: ) correspondence response: re: dry needling in the management of musculoskeletal pain simon vulfsons, md, and leonid kalichman, pt, phd to the editor: we congratulate dr. kent for having worked with dr. chan gunn for years. in the study published by ceccherelli et al, the comparison was made between superficial and deep dry needling for patients suffering from low back pain (lbp) of myofascial origin. in the methods section of their article, the authors state that the needles used were “( ) . needles (useful length of the needle, mm) for superficial insertion; ( ) . (useful length of the needle, mm) for deep insertion when the subcutaneous area is up to . cm thick; and ( ) . (useful length of the needle, mm) for deep insertion when the subcutaneous area is at least cm thick.” this will give to mm of effectual intramuscular needle length. in fact, the authors claim that the actual intramuscular stimulation length of the needles was approximately . cm, which is perfectly plausible. although this article was specifically focused on dry needling for myofascial pain in the whole body and not just the low back, we agree with dr. kent that classifi- cation of lbp has become one of a “waste basket” issue. unfortunately some authors classify according to specific and nonspecific causes of lbp, where by definition the nonspecific causes are nondiagnosable. , this approach invalidates myofascial physical examination, which is, ac- cording to some authors, not reliable. to our dismay, we even find soft tissue palpation being dumped as “worth- less.” it would be worth anyone’s time to read the excel- lent chapters about diagnosis in dummerholt’s and hui- jbregts’s book myofascial trigger points to realize the reliability of soft tissue palpation after appropriate train- ing. the treatment of myofascial trigger point (mtrp) pain is dependent on the release of the point, the reduc- tion of pain, and the restoration of normal function. on this there is agreement. where there is disagreement is on the etiology of mtrp generation. the central premise of travell and simons has been that an “adenosine triphosphate energy crisis” has caused the development of mtrps. simons implicated the motor endplate as the central etiology of these points. al- though motor endplate dysfunction is clearly at the heart of myofascial pain, gunn proposes that the reason that the endplates are dysfunctional is because of neuropathic nervous dysfunction causing target or- gan (in this case, muscle) supersensitivity. is it only the endplate or is it supersensitivity? this discussion is beyond the scope of this response, but should be ad- dressed in further detail in future studies. simon vulfsons, md pain relief unit, rambam health care campus rappaport school of medicine technion, haifa, israel leonid kalichman, pt, phd department of physical therapy, recanati school for community health professions, faculty of health sciences, ben-gurion university of the negev beer sheva, israel. kalichman@hotmail.com. references . ceccherelli f, rigoni mt, gagliardi g, ruzzante l. com- parison of superficial and deep acupuncture in the treatment of lumbar myofascial pain: a double-blind randomized con- trolled study. clin j pain ; : – . . deyo ra, weinstein jn. low back pain. n engl j med ; : – . . koes bw, van tulder mw, thomas s. diagnosis and treatment of low back pain. bmj ; : – . . dommerholt j, huijberts p. myofascial trigger points: pathophysiology and evidence-informed diagnosis and man- agement. sudbury, ma: jones and bartlett; . . simons dg, travell jg, simons ls. travell and simons’ myofascial pain and dysfunction: the trigger point manual. volume , nd ed. baltimore, md: williams & wilkins; . . simons dg. clinical and etiological update of myofascial pain from trigger points. j musculoskel pain ; : – . . gunn cc. radiculopathic pain: diagnosis, treatment of seg- mental irritation or sensitization. j musculoskel pain ; : – . doi: . /jabfm. . . jabfm january–february vol. no. http://www.jabfm.org o n a p ril b y g u e st. p ro te cte d b y co p yrig h t. h ttp ://w w w .ja b fm .o rg / j a m b o a rd f a m m e d : first p u b lish e d a s . /ja b fm . . . o n ja n u a ry . d o w n lo a d e d fro m http://www.jabfm.org/ untitled- © nature publishing group billion dollar mistake". not to be outdone, however, the sierra club res- ponded with an advertisement urging ruckelshaus to hold fast on the deadline. as for the manufacturers' first point, ruckelshaus stated last week that "the technological information available to me indicates that few catalysts will be required to meet this standard". but the manufacturers chorused that their infor- mation leads them to a different conclu- sion, and they hinted that they may take their case either to the courts or to congress. but as far as the standards relating to oxides of nitrogen are concerned, they may be on firmer ground and in any case they are likely to have the backing of the epa. in short, the epa has set a limit of micrograms of nitric oxide per cubic metre of air as the maximum level to protect health and it originally estimated that the limit is exceeded in regions throughout the united states. but it has since re- evaluated the concentrations using more precise techniques and will soon disclose that the level is exceeded in only two regions-los angeles and chicago. ruckelshaus in fact said last week that "our assessment of the health risk asso- ciated with (oxides of nitrogen) no longer supports the per cent reduc- tion standard and this should be reviewed quickly and, if our analysis is correct, the standard should be changed". the automobile companies would be delighted if congress accepts the need to change the standards because they have not yet found a reliable method for reducing emission of oxides of nitro- gen. so far, us companies are concen· trating on a dual catalyst approach but the nas committee said in its report that no system has yet been found to be reliable and that the dual catalyst has a huge fuel penalty, increasing gaso- line consumption by up to about per cent. the stratified charge engine developed by honda seems capable of meeting the standard for oxides of nitro- gen as well as those for hydrocarbons and carbon monoxide, however. the reason why the epa is anxious to protect the clean air act from being butchered is that it involves regulation of many sources of pollution in addition to automobiles and that changes in one area will affect others. the act requires the epa to set ambient air quality stan- dards nationwide and the states are empowered to meet the standards according to a specified timetable based on the emissions standards now estab- lished. but if the car makers are given more time to control exhaust emissions, many of the states' plans for meeting the air quality standards could be thrown badly out of kilter. in the final analysis, however, the us car makers have only themselves to blame if they end up using inferior technology to curb exhaust emissions. they began to work seriously towards pollution control only when the clean air act put a pistol to their heads and, unless they can now bully congress into giving them a second chance, they may have to pay for their mistakes on the market place when they compete with the japanese companies. energy research rumblings from congress by our washington correspondent although statements, reports and recommendations on the so-called energy crisis are by now two a penny, a report published last week by a special con- gressional task force merits careful reading. it suggests that spending by government and industry on research and development on new sources of energy has been unbalanced and insuffi- cient, and calls for at least an additional $ , million a year. the report is important because the task force which produced it has recently been promoted into a full subcommittee of the house committee on science and astronautics, and as such will have a strong voice in shaping legislation dealing with energy research. it is also a useful yardstick by which to measure president nixon's long overdue and eagerly awaited state- ment on energy policy, originally pro- mised for february and now expected to be unveiled this week. in short, the task force, which met under the chairmanship of mike mccormack, an energetic young con- gressman from washington, took a care- ful look at a report prepared for presi- dent kennedy in by an inter- agency committee, and concluded that most of its recommendations "are still valid today-valid because so little action has been taken to implement them". the task force also recommends that an energy policy group should be established in the white house and that all the energy programmes of the federal government should be central- ized in a single agency. the task force does not say exactly how the extra $ , million should be spent, or how it should be divided be- tween the federal government and industry. but it does suggest that past spending has been biased towards nuclear energy, and singles out seven priority areas which hold great promise and deserve more money. they are basic research-for example, the national science foundation's rann programme-materials science, solar energy, geothermal energy, breeder re- actors, coal gasification and liquefaction and controlled thermonuclear fusion. of these, only the breeder reactor has been given high priority by the admini- nature vol. april strati on, and then the money has been put into the liquid metal fast breeder almost to the exclusion of other designs. the suggestion that an extra $ , million should be spent on energy re- search and development is based on the task force's belief that per cent of the total national research and development effort should be devoted to energy. given the technologically intensive nature of the energy industries, such an expenditure is not unreasonable, the task force states, since total outlays on re- search and development in the united states are running at a little under $ , million. such a commitment would require about $ , million to be spent on energy research. but only some $ , million is expected to be spent next year, and of that about $ million will come from the government. viewed in conjunction with the energy research and development pro- gramme proposed by senator henry jackson and several of his colleagues (see nature, , ; ), the task force's proposals indicate which way the wind is blowing on capital hill. jackson's bill calls for expenditures by the federal government of $ , million a year over the next ten years on non-nuclear energy research. meanwhile, president nixon's budget for next year calls for only $ million to be spent on energy research and development, and in view of the admini- stration's present cost-conscious mood, the forthcoming energy message is not expected to add much more money to the budget request. funding for energy research is thus likely to be yet another bone of contention between the white house and congress. erratum the photograph that inadvertently appeared on page of this volume of nature was, of course, of britain's goonhilly , a £ . mil- lion satellite communication station which was opened last july. the s-inch mayall telescope that should have appeared is pictured above. 	erratum market quality and price discovery: introduction of the e-mini energy futures market quality and price discovery: introduction of the e-mini energy futures yiuman tse *, ju xiang department of finance, college of business, west durango blvd., university of texas at san antonio, san antonio, tx , united states received april ; received in revised form november ; accepted april available online september abstract in mid-june , the new york mercantile exchange (nymex) introduced e-mini futures contracts on natural gas and crude oil, a natural response to information technology developments and investor interest. the transition data allow examination of the effects of the new contracts on market quality and price discovery. bid–ask spreads on the regular futures have been reduced significantly since introduction of the e-mini futures, showing improved market quality from competition effects. the e-mini market contributes more than % to the price discovery process, although it represents less than % of the volume of the regular futures with the same underlying. e-mini futures have several advantageous characteristics over regular futures, which should explain these significant results. d elsevier inc. all rights reserved. jel classification: g keywords: e-mini futures; price discovery . introduction energy products and energy markets have played essential roles in the u.s. economy since the industrial revolution. energy markets have been much more volatile than the stock markets in recent years. during the -year period of through , the variances of daily returns of natural gas and cruel oil were . and . , while that of the stock index was only . (source: commodity systems inc. (csi) daily market files). gas and oil prices since - /$ - see front matter d elsevier inc. all rights reserved. doi: . /j.gfj. . . * corresponding author. tel.: + ; fax: + . e-mail address: yiuman.tse@utsa.edu (y. tse). global finance journal ( ) – deregulation in the s have been considerably more volatile than other commodity prices at most times. gas and oil prices are volatile because they are affected by many supply and demand factors, such as compacts among the organization of petroleum exporting countries (opec) and other oil-producing countries, the general economic environment, season of the year, storage circumstances, regulatory changes and so on. susmel and thompson ( ) find that broad regulatory changes from the s through the s had great impacts in the natural gas spot market, including increased volatility of prices and risks of market participation. in the s, opec cut oil production significantly, which led to the so-called energy crisis or oil crisis. more recently, investors have worried about labor strife and subsequent supply disruptions in venezuela and nigeria. the possibility of terrorist attacks targeting energy facilities, natural incidents such as hurricane lily in , and middle east conditions in have also greatly affected production and storage. economic entities such as energy producers, distributors, and financial institutions depend on efficient spot and futures markets for risk management and price discovery. energy futures contracts were introduced at the new york mercantile exchange (nymex) after the s mainly to hedge increasing energy risks. futures exchanges constantly introduce new financial products in response to developments in information technology and to meet the various needs of investors. a recent innovation is the use of e-mini futures, including equity index futures like e-mini sp , nasdaq and dow as well as commodity futures. an e-mini futures contract is smaller than a regular futures contract with exactly the same underlying pool of assets, and is usually traded electronically. on june , , nymex and the chicago mercantile exchange (cme) introduced two smaller sized energy futures, natural gas e-mini and light sweet crude oil e-mini futures [called e-miny energy futures(sm)]. e-mini natural gas and crude oil futures contracts are % of the size of the regular futures contracts; that is, . e-mini futures contracts equal one regular futures contract. they are traded through cme’s electronic trading platform (globex), and not on the open outcry market where regular futures are traded. according to nymex, the smaller sized e-mini futures were designed to appeal to individual speculators–not nymex’s typical customer–in the energy markets. the margin requirements of e-mini futures are smaller than those for the regular contracts. therefore, e-mini futures are more affordable to individual investors who were previously unable to trade at nymex. unlike their regular counterparts, the e-mini contracts are cash-settled. some commercial entitles may use the e-mini futures for hedging odd lots. the appendix provides detailed specifications of the two futures contracts and two news articles by securities week ( a, b) describe the benefits of e-mini futures to individual investors. we examine the impact of introduction of e-mini futures on the regular futures. e-mini products might have multiple effects on the regular products since e-minis are both electronically traded and smaller in size. whether market quality will be improved through competing trading systems depends on two opposite effects: competition and fragmentation during the same -year period, the variances of gold, live cattle, and soybean daily returns are . , . , and . , respectively. the gas markets are also more volatile than other commodities and the s&p index during the longer period of through . results are available upon request. members of the nymex and cme have access to one another’s electronic system for e-mini trading. cme members are granted access to nymex accessr to trade nymex division products. those trades receive discounts and are guaranteed by a nymex clearing firm. similarly, nymex members receive trade access, discounts, and clearing guarantees for products listed on cme’s globex. y. tse, j. xiang / global finance journal ( ) – https://isiarticles.com/article/ * corresponding author, tel: + – – – current status and outlook of renewable energy development in nigeria m. f. akorede , o. ibrahim ,*, s. a. amuda , a. o. otuoze , b. j. olufeagba advanced power and green energy research group, , , , dept. of electrical & electronics engineering, univ. of ilorin, ilorin, kwara state. nigeria. department of computer engineering, university of ilorin, ilorin, kwara state. nigeria. e-mail addresses: akorede@unilorin.edu.ng, ibrahim.o@unilorin.edu.ng, amudasulyman@gmail.com, otuoze.ao@unilorin.edu.ng, olufeagba.bj@unilorin.edu.ng abstract over % of the current nigerian primary energy consumption is met by petroleum. this overdependence on fossil fuels derived from petroleum for local consumption requirements should be a serious source of concern for the country in two ways – depletion of the resources and negative impact on the environment. this paper presents a critical review of the available renewable energy resources in nigeria, namely; biomass, hydropower, solar and wind energy. it examines the current energy situation in the country and equally discusses the various energy policy documents developed by the government. using the scenario-based international atomic energy agency models, the projected energy demand and supply structure of the country through are presented and analysed. overall, this study shows that nigeria will overcome her present energy crisis if she explores the abundant renewable energy resources in the country. the data presented in this paper is a crucial eye-opener for relevant government agencies towards developing these energy resources in tackling the present energy crisis in nigeria. keywords: renewable energy, per capita energy, nigeria, biomass, fossil fuels, growth scenario . introduction energy is a vital ingredient for development and a powerful engine of social and economic change in any country or region. it is at the heart of everybody’s quality of life and a critical factor for economic development. the need for energy can never be over-emphasised in the contemporary world; it is indeed fundamental to the fulfilment of basic individual and community needs in our modern society. lighting and heating a house, running a factory, lighting a street, keeping a hospital open and operational, provision of potable water, etc, all require energy. since the aforementioned services are the indices by which a nation’s progress and level of development are measured, it follows that the amount of energy consumed by a country at a particular instant of time largely determines the country’s economic and social development [ , ]. renewable energy is energy generated from natural resources such as sunlight, wind, rain, tides, and geothermal heat. it is derived from natural processes that are constantly replenished. each of these renewable sources has unique characteristics which influence how and where they are used. globally in , about % of total energy consumption came from renewables, with % coming from traditional biomass like fuelwood, and % from modern renewables such as biomass for heat production and vehicle fuel , geothermal, biofuel, solar, wind and hydropower [ ]. the share of renewables in electricity generation at the end of is around . % with . % coming from hydropower, . % from wind and . % from other new renewables [ ]. to date, fossil fuels, majorly coal, oil and natural gas have been the principal sources of energy worldwide. for instance, more than three-quarters amounting to . % of total world energy demands in was fulfilled by fossils [ ]. still, report shows that the demand for these fuels grows in absolute terms through [ ]. however, burning of fossil fuels has been identified to create two adverse effects on our environment; (i) it produces greenhouse gas (ghg) emissions that cause global warming, and (ii) the by-products of burning, such as sulphur dioxide, soot, and ash that are responsible for global dimming by changing the properties of the clouds [ ]. therefore, the need to conserve our environment nigerian journal of technology (nijotech) vol. , no. , january , pp. – copyright© faculty of engineering, university of nigeria, nsukka, print issn: - , electronic issn: - www.nijotech.com http://dx.doi.org/ . /njt.v i . http://www.nijotech.com/ http://dx.doi.org/ . /njt.v i . current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january from these pollutants led to a global search for alternative clean energy sources. another driver responsible for the interest in the renewable energy is the rising concerns about the security of energy supplies. sustainability is a key factor influencing the long-term viability of any energy resource, and it comes as no surprise that it is at the forefront of the global campaign to abandon the use of dwindling fossil fuels reserves. though blessed with abundant renewable energy resources, nigeria is yet to fully harness them to play a significant role in energy production. however, the nigerian government has taken some steps towards encouraging the use of renewable and alternative energy resources in different sectors of the economy. for example, the long term renewable energy masterplan developed by the energy commission of nigeria (ecn) is to address the challenges of moving towards clean, reliable, secure and competitive energy supply in nigeria. the main goal of this document is to reduce projected energy use by % by and meet % of the nation’s electricity needs with class renewable energy sources like solar energy, wind energy and fuel cell by year . similarly, the federal executive council approved in the biofuel policy framework presented by the nigerian national petroleum corporation (nnpc). the policy was targeted at supplying the internal market with % ethanol blend with gasoline (e ) to drive engines and vehicles [ , ]. this mandated nnpc to set up a renewable energy division (red) to develop private sector driven investments in ethanol production as alternatives to fossil fuels [ , ]. the biodiesel projects initiated includes the biodiesel nigeria limited’s biodiesel initiative in lagos state, aura bio-corporation’s tolao biodiesel project in cross river state and the shashwat jatrophal biodiesel limited’s biodiesel project in kebbi state [ , ].in the same vein, the federal government established six energy centres for research across the geopolitical zones, affiliated to the ecn saddle with the responsibility of developmental research on renewable energy application in the nation [ ]. the prime aim of this paper is to review the electric energy demand and supply in nigeria, and examine the current status of renewable energy resources and their potentials towards contributing to the socio-economic growth of the country. the quantitative data on the available renewable resources such as biomass, hydropower, solar and wind energy with their current usage are presented. the novelty of this work over the existing studies [ - ] on this subject is that data are not just presented in their raw form but the amount of energy that could be generated are estimated from technical point of view using the approach of the authors’ previous study. the distribution across the country as well as the estimated amount of these resources is analysed. the information presented in this article will serve as an essential tool to sensitise relevant government agencies and non-governmental organizations towards fully tapping these abundant energy resources to practically contribute to the energy production in nigeria. . current energy scenario in nigeria nigeria is a rich country blessed with both fossil fuels such as crude oil, natural gas, coal, etc, and renewable energy resources like solar, wind, hydro and biomass. details of this are shown in table constructed with data obtained from the nigerian national petroleum corporation, renewable energy masterplan and ministry of mines and steel development [ ]. it is seen from the table that nigeria has a reserve of . billion barrels of crude oil, trillion standard cubic foot (scf) of natural gas at standard temperature and pressure ( degrees f and sea level), and . billion tonnes of coal and lignite of which virtually nothing has been tapped. the nigeria’s reserve for large hydropower is estimated at , mw and , mw for small hydropower. nigeria has a reserve of million hectares of forest and woodland and million hectares of agricultural land waste land. based on the available statistics, nigeria produces about , tonnes of fresh animal wastes daily. if fully utilised, this quantity is equivalent to . million m of biogas production every day [ ]. despite this abundance of energy resources in nigeria, the country is currently facing energy crisis due to the country’s grossly inadequate energy supply that is incapable to meet the ever-growing demand. essentially, the major energy-consuming activities in nigerian households are cooking, lighting and use of electrical appliances. based on estimates carried out in [ ], cooking accounts for about % of household energy consumption, lighting uses up % and the remaining % goes to the use of basic electrical appliances such as television and pressing iron. to date, the national energy supply in nigeria is entirely dominated by fossil fuels. renewable energy resources are grossly underutilised in the country despite their availability in reasonable quantities. table , obtained from central bank of nigeria (cbn) report, shows the primary energy consumption by type. it is apparent from the table that while coal has over a long period been neglected, petroleum has constituted over % of the commercial primary energy consumed in the country. however, it is paradoxical to say that in spite of nigeria’s rich oil and gas sector, % of the population do not have access to electricity which is a secondary form of energy fuelled by the petroleum with which nigeria is richly endowed [ ]. current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january table : energy resources in nigeria resource reserves (natural units) production level (natural units) utilisation (natural units) crude oil . billion barrels . million bpd , bpd natural gas trillion scf . billion scf/day . billion scf/day coal and lignite . billion tonnes insignificant insignificant tar sands billion barrels of oil equivalent large hydropower , mw , mw ( . million mwh/day) . million mwh/day small hydropower , mw mw ( . million mwh/day) . million mwh/day solar radiation . – . kwh/m /day excess of kwp of solar pv or . million mwh/day excess of . million mwh/day solar pv wind – m/s at m height - - biomass fuelwood million hectres of forest and woodland . million tonnes/day . million tonnes/day animal waste million assorted animals in . million tonnes of waste/day in not available energy crops and agric. residues million hectares of agric. land and all waste lands excess of . million tonnes of assorted crops residues/ day in not available * scf – standard cubic feet * bpd – barrel per day table : primary energy consumption by type. type percentage of total average coal . . . . . . . hydropower . . . . . . . natural gas . . . . . . . petroleum products . . . . . . . source: cbn annual report ( , ) the per capita energy consumption in nigeria is one of the very lowest in the world – about one-sixth of the energy consumed in developed countries. this is directly linked to the level of poverty in the country. figure is presented to illustrate the per capita energy consumption in nigeria for – . the falling trend of energy consumption from . toe/capita in to . toe/capita in before stabilising at . toe/capita in could be observed. these values may be compared with a value of . toe/capita obtained in gabon, . toe/capita in libya and . toe/capita in south africa for the year . the scenario in the chart could be linked to a steady increase in population without a corresponding increase in energy production and consumption. it is a fact that no country can develop or witness any significant growth without proportional growth in its primary energy exploration for secondary energy production like electricity as mostly required by the industries and consumers. figure : per capita energy consumption in nigeria for – . evidently, nigeria provides a classic example. the per capita electricity consumption per annum in nigeria is plotted and shown in figure along with a few other current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january african countries [ ] . as shown in the figure, the per capita electric energy consumption in nigeria for an average household of five people was kilowatt-hours (kwh) per annum for the year . this value is among the lowest ten in the world. incidentally, studies have shown that there is a strong correlation between energy consumption and economic growth; access to modern electric energy directly contributes to economic growth and poverty reduction of a country through creation of wealth [ ]. the abysmal low annual per capita electricity consumption in nigeria obviously constitutes a major roadblock to economic progress and social well- being of the citizenry. figure : per capita electricity consumption of a few african countries. . energy demand and supply projections for nigeria in a bid to aggressively address the lingering energy crisis faced in the country, the international atomic energy agency (iaea) scenario-based model was used to model the demand structure of nigerian energy sector in four scenarios. the developed model is for the analysis of energy demand tagged “model for analysis of energy demand” (maed). it evaluates future energy demands based on medium to long term scenarios of socioeconomic, technological and demographic development. these are combined to give an overall picture of future energy demand growth. similarly, another model called message i.e. the model for energy supply strategy alternative and general environmental impacts, also developed by iaea was used to estimate the supply strategy for meeting the energy demand in nigeria. message combines technologies and fuels to map energy flows from supply to demand. the four scenarios used were reference growth, high growth, optimistic i and optimistic ii with average gdp growth of %, %, . % and % per annum respectively [ ] . the projected energy demand and corresponding electricity demand for the country from through , using the previously mentioned maed model, are depicted in figures and respectively. similarly, table presents the projected electricity supply by fuel mix for nigeria for the reference growth scenario. from the table, a total of , mw was targeted for the year . it is however, unfortunate that even as at th october ; nigeria’s peak electricity generation was less than , mw [ ] . this value is approximately equal to % of the target. judging by this development, it would be very difficult to achieve a total of , mw of electricity projected for in the country. figure . the energy demand projections for the four economic growth scenarios. figure : the electricity demand projections for the four economic growth scenarios. table : projected electricity supply by fuel mix for % growth. scenario (mw) (mw) (mw) (mw) (mw) coal , , , , gas , , , , , hydro , , , , , small hydro nuclear , , , solar wind , , , total supply , , , , , source: energy commission of nigeria ( ) the contribution of renewable energy resources for the targeted electricity generation is shown in table . the main renewable energy resources expected in the reference growth scenario are large and small current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january hydropower, solar and wind energy. overall, the aforementioned renewable energy resources were to constitute about % of the total energy resources in year . thin contribution is targeted to increase to % of the total energy production by . table : target for renewable energy contribution to electricity generation in nigeria. resource (mw) (mw) (mw) large hydro , , , small hydro , solar pv solar thermal biomass wind total re , , , total energy resources , , , percentage of re (%) source: renewable energy master plan for nigeria, ecn . . overview of draft energy plans in nigeria the energy commission of nigeria is the government body saddled with the responsibility to coordinate activities within the energy sector as well as overseeing the implementation of the objectives spelt out by the energy policy. the commission has developed a number of draft policy documents for the energy sector of the country. quite a number of these documents have provisions that are relevant to the development of the policy guideline. the constitution of the federal republic of nigeria, the national economic empowerment and development strategy (needs) in , the national electric power policy ( ), electric power sector reform act and the national energy policy of [ , ] are all examples, to mention but a few. the constitution places electricity generation, transmission and distribution on the concurrent legislative list. the intent is to involve all tiers of government in most aspects of the electricity supply industry. the following are the set of targets proposed by needs to be met by the power sector by , some of which include highlights of the federal government’s mandate to the former public utility national electric power authority (nepa):  expeditiously implement the electric power sector reform program  increase generation capacity from the existing plants from , mw to , mw  increase transmission capacity from , mva to , mva  increase distribution capacity from , mva to , mva  reduce transmission and distribution losses from % to %  explore alternative energy sources, such as coal, solar power, wind power, and hydropower  deregulate the power sector to allow increased private sector participation the electric power sector reform (epsr) act of of which most of the significant provisions of national electric power policy (nepp) of are contained, was passed to liberalise the power sector and remove government’s monopoly on generation and distribution. consequently, the nigerian electricity regulatory commission (nerc) was established to create a level playing field for all stakeholders and licence players in the sub-sector. the epsr act emphasises the role of renewable electricity in the overall energy mix, especially for expanding access to rural and remote areas. the national energy policy (nep) was developed by ecn and approved by the government in . the document launched in is the origin of the various master plans, such as renewable energy master plan (remp), and national energy master plan (nemp) in drafted thereafter. the overall thrust of the energy policy stated in it is “optimal utilization of the nation’s energy resources for sustainable development”. the draft remp articulates nigeria's vision and sets out a road map for increasing the role of renewable energy in achieving sustainable development. the nemp contains action plans that guide its implementation to ensure the development of nation’s energy resources with diversified energy resources option for enhanced achievement of national energy security [ ]. however it is worth stating here that most of the draft policy documents are yet to become legal documents as they are awaiting government approval. before they can attain the final implementation stage, the following three levels are crucial [ ]:  approval by the federal government  legislation into law by the national assembly  strict adherence to implementation by concerned ministries, departments and agencies (mdas) . renewable energy potential in nigeria renewable energy sources have contributed to nigeria’s energy mix in the last few centuries, notwithstanding in a largely primitive way. for example, fuelwood is the longest standing primary energy source for rural dwellers in nigeria, just as for several other african countries. similarly, large hydropower has contributed in no small measures as an energy source, providing about % of nigeria’s national electric grid supply [ ]. current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january adoption of ‘new’ renewable energy sources such as solar photovoltaics, solar thermal, wind, small hydropower and efficient biomass in the country is relatively recent. nigeria is endowed with abundant quantities of each of these resources. this section of the paper looks into the available and potential of renewable energy resources in the country. . biomass energy biomass is any organic material from plants and animals that store sunlight in the form of chemical energy. it is foreseen as one of the most important energy sources among the renewable energies in the near future. generally, sources of biomass as shown in figure include virgin wood, energy crops and agricultural residues, industrial wastes, sawmill residues, etc. biomass fuels are overwhelmingly the most important energy source for rural households, agricultural production and rural industries particularly in developing countries [ ]. modern biomass energy recycles organic waste from forestry and agriculture, like corn stovers, rice husks, wood waste and pressed sugarcane, or uses special, fast-growing ‘‘energy crops’’ such as willow and switchgrass, as fuel. based on the us international energy agency (iea) report, % of the world’s energy, both heat and power, is currently derived from biomass [ ]. the potential of biomass to help meet the global energy demand has been widely recognised in the literature [ - ]. depending on the type, when combusted, the chemical energy in biomass is released as heat that is used to produce steam which could in turn be used to either drive a turbine for electricity production or provide heat to industries and homes. to combust biomass involves burning it in air at a flow rate of – kg of air per kg of biomass [ ]. biogas and biofuel technologies are now widely used to convert organic biomass matters to gaseous and liquid states respectively. figure : forms of biomass and products there exists a huge potential for the successful deployment of biomass energy in nigeria, most especially in the rural agricultural areas. majorly, the three forms of biomass available in nigeria as shown in table are fuelwood, animal wastes and energy crops and agricultural residues. according to a report, nigeria has a reserve of million hectares of forest and woodland, million assorted animals in and . million hectares of arable land, which is approximately equal to % of the total land. all these produce in excess of . million tonnes of biomass per day [ ] . in , a total estimate of . pj of biomass, consisting of animal and agricultural wastes, and wood residues, was made for nigeria. furthermore, research revealed in that bio-energy reserves/potential of nigeria stood at million hectares of fuelwood, million tonnes per year of animal waste, and million tonnes of crop residues [ ] . . . fuelwood nigeria is naturally rich in fuelwood and is the most dominant biomass resource used in the country. it accounts for % of the biomass used in the country with agricultural residues accounting for most of the remaining %. annually, nigeria consumes over million metric tonnes of fuelwood [ ] . the annual production of agricultural biomass is enormous due to the fact that about % and % of nigerian households are engaged in crop farming and livestock farming respectively. currently, over % of the population, most especially the rural dwellers, take wood as the main source of fuel. the reason behind this is that these people cannot afford to pay for commercial cooking fuels such as kerosene and gas. even those that can afford the price are often forced to resort to using wood and charcoal in larger cities whenever there is acute shortage of the cooking fuels in the country. however, excessive wood- gathering activity, without replacement, has caused critical depletion of this resource. the expected implication of this act on the environment is that woodlands run the risk of deforestation, which in turn increases the risk of other hazards such as erosion and flood particularly in the south-eastern part of the country. vigorous research efforts have globally been made to develop more efficient woodstoves to replace the inefficient traditional three-stone open fires commonly used for cooking in rural areas, as shown in figure . these research efforts have started to yield positive results, one of which is the save . the save , shown in figure , is a high-quality energy efficiency metal cookstove that saves up to % of the required firewood compared to the traditional open fires where only – % of the wood is converted into heat energy. it current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january is developed specifically for use in areas with low fuelwood availability as well as in a number of refugee camps throughout africa. the “efficient wood fuel stoves for nigeria” programme is a joint initiative of the german ngos, and a nigerian counterpart, developmental association for renewable energies (dare) to promote dissemination of more efficient cooking stoves to households in nigeria. figure : the traditional three-stone cooking stove figure : highly efficient wood saving stove it is the third registered clean development mechanism (cdm) project in nigeria tagged cdm project . so far over , save stoves have been sold to customers at reduced price [ ] . during the lifespan of the project, it aims to distribute about , save stoves to improve women’s welfare and livelihoods in the project area of the guinea savannah zone of nigeria. . . animal waste the process involved in the conversion of animal waste to biogas to electric energy include the following: mixing of waste to homogenise it; digestion of waste in an anaerobic digester; separation of sludge; biogas collection from digester; and power generation from biogas. estimates made in gave the total number of cattle, sheep, goats, horses and pigs as well as poultry in nigeria as million. these all together produce . million tonnes of animal waste daily which is equal to . x mj with the calorific value of animal dung assumed as , mj/tonne [ ]. table shows the biogas production rates for a number of feedstock materials, majorly animal wastes [ ]. table : biogas production rates for a variety of feedstock materials resource gas production (m /kg) methane content (%) retention time (days) cattle manure . – . n/a n/a poultry manure . – o. – – pig manure . – . – – sheep manure . – . msw . – . – – according to a study reported by odeyemi [ ], nigeria has a potential of about . million m of biogas production every day from animal waste only. the referenced feedstock materials for biogas production in the study include poultry manure in homes and commercial poultry farms. . . energy crops and agricultural residues agricultural residues are classified into crop or field residues and processing residues. while crop residues are the materials left on the farm after harvesting the target crops, processing residues are produced mainly after crop processing [ ]. crop residues produced in nigeria include straw leaves and stalks of cereal, cassava peelings and cocoa pods. on the other hand, processing residues include cocoa husk, coconut shell and husk, rice husk, etc. the major agricultural crops grown in nigeria are millet, yam, cassava, sorghum, rice, groundnut, oil palm, jatropha, soyabeans, and maize. among all, the crops that have sustainable potential as biomass feedstock for biofuel production include sugarcane, sorghum, cassava, rice, and maize, while oil palm, groundnut, jatropha, soyabeans, sunflower, castor oil, and sesame are famous for biodiesel production [ ]. table shows the estimated production data and biofuel type of major nigerian agricultural crops for the year [ ]. using the residue to production ratio (rpr) approach, iye and bilsborrow [ ] estimated the energy potential from major agricultural crop residues in nigeria from – under three different scenarios. according to the study, scenario , which is a more realistic one, yielded a total sum of . tg of feedstock, which is equivalent to . pj potential energy. on the other hand, processing residues produced a total of . tg feedstock, equal to . pj of energy. this gives a grand total of . tg and pj annual feedstock and potential energy respectively as illustrated in table . it could be observed from the table that cassava and yam current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january peelings form about % of the total processing residues. table : estimated crop output and biofuel type in for nigeria. resource crop production (million metric tonnes) crop residue production (million metric tonnes) derivable biofuel type cassava , , , , bioethanol yam , , , , bioethanol millet , , , , bioethanol maize , , , , bioethanol rice , , , , bioethanol potato , , , bioethanol cowpea , , , , biodiesel groundnut , , , , biodiesel oil palm , , , biodiesel sugar cane , , bioethanol sweet potato , , , , bioethanol cocoyam , , , , bioethanol coffee , , biodiesel cashew , , biodiesel plantain , , , bioethanol sorghum , , , , bioethanol table . average annual agricultural crops residues for bioenergy production in nigeria ( - ). crop residue type residue amount (gg) energy (pj) maize stalks , . . cob , . . cassava stalks , . . peelings , . . rice straw , . . husk . . groundnut straw , . . husk , . . yam peelings , . . sorghum straw , . . millet straw , . . groundnut straw , . . total , . . * gg – gigagrams (equal to g) * pj –petajoules (equal to j) the results of a study of the availability and productivity of grasses, weeds and leaves as energy resource, conducted by osadolor [ ] in six selected sites across nigeria is shown in figure . the objective of this study was to ascertain that the resources will be available for use as energy raw material in the country. it should, however, be noted that the results shown in the figure is the calculated average values for three years – to . it is glaringly evident in the figure that buruku-jos has the highest biomass production of , g/m per year, followed by ekpoma. the study revealed an annual incremental yield of the resources which varied from g to g. . . municipal solid wastes another source of biomass in nigeria is municipal solid wastes (msw). these are materials generated from the daily activities of humans. essentially, msw contains two basic components – biodegradable and non- biodegradable matter [ ] the biodegradable fraction is usually treated by anaerobic digestion for production of biogas, which could in turn be used for cooking or power generation depending on the scale of production. municipal solid wastes management in nigeria includes both open dump in unmanaged sites and controlled sanitary landfills. organised sanitary landfills are limited to major urban cities such as abuja, lagos, ibadan, akure and other state capitals. the average msw produced per capita per day significantly varies from place to place in nigeria. however, kg of msw per capita has been estimated to be produced in the country annually [ ]. going by the census figure of million inhabitants, the total generated msw will be at least . million tonnes per year. with increasing urbanisation and industrialisation, the annual msw generated will continue to increase. therefore, biogas production from these wastes will be a profitable and viable means of reducing the menace and nuisance of urban wastes in many cities. figure : average annual biomass production across selected areas in nigeria. figure : monthly msw generated in nine major cities in nigeria. current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january figure is presented to illustrate the monthly amount of msw generated in a few major cities in nigeria [ ] . it follows from the results that a total of . million metric tonnes of msw will be generated per annum from these nine cities. . hydroelectric power hydroelectric power (hep) is one of the few sources of energy that has assumed great significance since the beginning of the twentieth century. it produced about a quarter of the world's electricity and supply more than one billion people with power. hep plants are continuously gaining importance as a renewable and non-polluting source of electricity generation [ ]. statistically, it is the most common form of renewable energy and plays a very important role in the global energy production [ ] . according to the international energy agency (iea), the global generation of electricity from hydropower in was , . twh, accounting for almost % of total global energy production. the global technical potential is estimated at more than , twh/year. figure shows the values of installed capacity as percentage of the total of , twh by region in , where oecd is the organisation for economic co-operation and development. currently about % of world’s hydropower potential is used effectively [ ] . figure : hydropower installed capacity by region as at nigeria has three main hydropower plants. these plants are located at kainji, jebba, and shiroro power stations with installed capacities of mw, mw and mw respectively; totalling , mw [ ]. these three hydropower plants contribute about . % power to the national grid [ ], thus making hydropower the country's largest renewable energy source. the fourth hydropower station, owned by a private utility service company, the nigerian electricity supply corporation (nesco) limited, is located at six different sites in plateau state but has a total potential of just mw [ ]. shiroro power plant was commissioned in with an installed capacity of mw. kainji and jebba power stations operate as two hydro generation plants, each being from the river niger. kainji began operation as nigeria's first hydro power plant in while the jebba plant was commissioned in [ ]. the installed capacity of the hydropower plants in nigeria has remained stagnant for many years while the output power produced has continued to decline due to lack of proper maintenance leading to loss of generating units and seasonal fluctuations in the volume of water flowing into the reservoirs [ ] . hydro-energy has the most potential for development in rural areas of nigeria due to its abundance and generally available well-known technology. its projects create favourable conditions for new productive activities related to the supply of materials and equipment which usually generates employment during construction. since the main obstacle to these projects is lack of finance, it is advisable to concentrate on small hydropower stations that can complement rural electrification programmes in addition to the advantage of water supply and irrigation systems from the dams [ ] . however, there was a shift in attention to fossil fuels due to the vast deposits in the country, at the expense of the hydropower sector. the result was that the three existing hydro plants (kainji, jebba and shiroro) were neglected to the extent that they now perform well below installed capacity [ ]. nigeria has considerable hydro potential sources exemplified by her large rivers, small rivers and streams. nigerian rivers are distributed all over the country with potential sites for hydropower scheme which can serve the urban, rural and isolated communities. an estimation of rivers kaduna, benue and cross river at shiroro, makurdi and ikom indicates that a total capacity of about , mw is available, while the estimate for the river mambillla plateau is put at , mw. a large number of untapped hydropower potential of about , mw has been identified in various locations across the country, as shown in table [ ] . recently, the federal government of nigeria signed $ . bn contract with a chinese company for the development of zungeru power plant aimed to generate about mw. table : nigeria’s hydropower potentially identified locations and their capacities. location river state potential capacity (mw) mambilla danga taraba , lokoja niger kogi , makurdi benue benue , onitsha niger anambra , ikom cross cross river zungeru i kaduna niger current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january location river state potential capacity (mw) zungeru i kaduna niger yola benue adamawa gurara gurara niger katsina ala katsina ala benue beli se taraba kano donka niger adamawa afikpo cross ebonyi afikpo cross ebonyi garin dali taraba taraba gembu dongo taraba karamti kam taraba sarkin-danko suntai taraba kiri gongola adamawa oudi mada benue richa i mosari nassarawa gwaram jama’are adamawa ifon osse ondo kashimbila katsina ala benue korubo gongola adama/taraba kura ii sanga kano richa ii dafo kano mistakuku kurra plateau kura i sanga kano kafanchan kongum kaduna total , small hydropower (shp) has been in existence in nigeria since . however, shp technology is still at its infancy in nigeria with the scheme operated in only three states of the country [ ]. if properly deployed, shp can be the most affordable and accessible option to provide off-grid electricity services especially in rural communities. based on nigeria’s level of hydropower development, small hydropower station is defined to be of capacity between mw and mw, though, there is no internationally precisely agreed range or limit, and most countries use this limit to define shp. pre-feasibility studies and reports had already been prepared for twelve ( ) identified sites and four ( ) river basins, over unexploited shp sites with total potentials of . mw were identified and are awaiting investments, however, shp potential sites exist in virtually all parts of nigeria with an estimated capacity of , mw [ ]. so far about nine ( ) small hydropower stations with aggregate capacity of mw has been installed in nigeria by private companies and the government as shown in table , with the power stations in bakalori, tiga and oyan requiring rehabilitation [ ]. in contrast to the developed countries where shp plants find broad adoption in electricity production and other applications, little attention is given to its significance in nigeria despite its vast potential and the high energy demand. however, a estimation indicated a total capacity representing % of the nation’s hydropower potential if the remaining states were surveyed [ ] . table : existing shp schemes in nigeria river state installed capacity (mw) bagel i plateau . bagel ii plateau . ouree plateau . kurra plateau . lerre i plateau . lere ii plateau . bakalori sokoto . tiga kano . oyan ogun . total . the small and large hydropower potential of nigeria stand at , mw and , mw respectively [ ] . the federal government put in place a framework towards exploring available potentials for shp, thus requiring the efforts of every sector. however, private sector participation has increased only in fossil-based sources rather than in hydropower and other renewable sources. figure shows some shp surveyed in some selected states of nigeria [ ]. figure : small hydro potential surveyed in some selected states of nigeria. for small and medium hydropower, the hydropower projects are located in nine states (gombe, kaduna, kano, katsina, ondo, ogun, oyo, sokoto, and zamfara). the total capacity of the hydropower projects is given as mw [ , ] . although planned renewable energy accounts for about % and % of the additional , and , mw to be added to the grid by and , respectively, the majority of that is large-scale hydropower plants aimed at addressing irrigation and water supply problems in addition to power supply [ ]. . solar energy nigeria is richly endowed with solar energy with an annual average daily sunshine of . hours, ranging from hours at the coastal areas to hours at the far northern boundary. studies have shown that nigeria receives an current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january average solar radiation of . kwh/m a day at coastal latitude and kwh/m a day at the far north [ , , ]. if the right technology is put in place, solar radiation in almost every locations in nigeria is viable for electricity generation [ , ]. figure shows the yearly average daily sum of global horizontal irradiation for cities across nigeria between period of – as obtained from geosun africa, stellenbosch south africa, a subsidiary to solargis weather data provider [ ]. figure : nigeria solar radiation map. despite the availability of solar power resources in the nigeria, solar pv installation is limited and disperse in country with majority in remote areas for standalone applications like solar water pump. though solar pv installation is said to have been on gradual increase, it was reported by sambo in year to have reached about mw [ ]. more than % of the installations belong to government agencies for water pumping, street lighting, vaccine refrigerators, and community lighting. its domestic application is not yet pronounced because people are yet to be convince that it’s viable alternative to small size generators due to high capital cost. nigeria is also far behind in research on solar cell development and manufacturing. however, the national agency for science and engineering infrastructure (naseni) took a giant step towards having nigerian branded solar pv by establishing a solar assembly plant in karshi, abuja in the year . the solar assembly plant commenced operation in the same year, even though none of the component parts is been manufactured in nigeria yet. effort like this should be supported by the government and private sector to ensure sustainability. the researchers in the country should also embark on relevant research that will take the country to a level of locally producing accessories components soonest with expectation of attain production of solar cells. local manufacturing of solar pv will drastically bring down the cost of installation and promote availability and accessibility thereby promotes adoption of solar energy as viable alternative source of energy in the country. . . solar irradiance data collection the solar irradiance and the sunlight day hours determines the potential solar energy that can be generated at any specific location. estimating potential electricity generation from solar radiation can be tasking because of associated incessant variation and changing dynamics of weather conditions [ ]. these factors are hindering reaching the full potential of solar energy for electrical energy generation. despite this variation, it has been established that the minimum solar radiation in any part of nigeria is viable for electricity which can fulfil the daily energy needs for lighting, heating, and powering appliances like computer system, television, and refrigerators [ ]. in nigeria, the major source of weather data is nigerian meteorological agency (nimet) which has sparse data gathering centre at airports around the country. most of the airports have limited facilities to capture accurate solar radiation data because there primary interest lies in other weather data such as temperature, relative humidity, rainfall for their smooth operation. institutional research centre is another source of solar radiation data in the country but apart from been site specific, data measured are usually on short term basis in a period of one year or two years. the pvgis- africa solar irradiance data was used for assessment of potential solar electricity generation by pv modules mounted at horizontal and optimal inclination for selected nigeria cities covering a period of - [ , ]. the sites were randomly picked across the six geopolitical zones of the country from the far north of sokoto (nw), maiduguri (ne), through the central abuja (nc), ilorin (nc), down till south, ibadan (sw), enugu (se) to portharcourt (ss). table shows the monthly average global irradiation at horizontal and optimal inclined surface (kwh/m /day) of some selected nigeria cities. . . estimation of solar energy potential in nigeria there are two numerical approaches to estimate the annual energy production from solar irradiance. the first method involves estimation based on solar pv module area as stated in equation. ( ) [ ]. ( ) hi r e arg p kwh ( ) current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january table : monthly averaged daily global irradiation (kwh/m /day) in nigeria ( – ). month sokoto hh hopt maiduguri hh hopt abuja hh hopt ilorin hh hopt ibadan hh hopt enugu hh hopt p. harcourt hh hopt jan . . . . . . . . . . . . . . feb . . . . . . . . . . . . . . mar . . . . . . . . . . . . . . apr . . . . . . . . . . . . . . may . . . . . . . . . . . . . . jun . . . . . . . . . . . . . . jul . . . . . . . . . . . . . . aug . . . . . . . . . . . . . . sep . . . . . . . . . . . . . . oct . . . . . . . . . . . . . . nov . . . . . . . . . . . . . . dec . . . . . . . . . . . . . . average . . . . . . . . . . . . . . *hhis irradiation on horizontal plane; *hopt is irradiation on optimally inclined plane source: pvgis © european communities, - table : estimated electricity generation from kwp pv module in selected nigerian cities. city latitude (north) longitude (east) optimal inclination angle (º) yearly averaged daily radiation (kwh/m /day) annual electricity generation (kwh) sokoto ° ' " ° ' " . , . , maiduguri ° ' " ° ' " . , . , abuja ° ' " ° ' " . , . , ilorin ° ' " ° ' " . , . , ibadan ° ' " ° ' " . , . , enugu ° ' " ° ' " . , . , port-harcourt ° ' " ° ' " . , . , total . , in ( ), e is estimated annual energy in kwh , a is total solar panel area in m², r is solar panel yield (%), ghi is yearly average daily irradiation on pv module at horizontal/inclination, and pr is system performance ratio, coefficient for (typical value for roof mounted system with modules from mono-crystalline or polycrystalline silicon is . ) to assess the potential electricity generation for the selected location with average global irradiance for horizontal or optimal inclined ( hi g ), the performance ratio ( r p ) is taken as . and a unit peak power ( k p ) of kwp pv module is assumed. the total annual estimated energy output (e) of a photovoltaic system is calculated from equation ( ) [ - ]. rhik pgpe  )(kwh ( ) table presents the estimated solar energy that can be generated in different cities across nigeria for both horizontal and optimal inclined solar pv modules. the yearly sum of estimated electricity that can be generated from kwp pv module at horizontal solar irradiance ranges from , kwh in the far north to , kwh at the southern part of the country. the northern part demonstrates strongest potential for solar electricity as maiduguri has the highest yearly average daily global irradiance of . kwh/m per day at horizontal and . kwh/m at optimal inclined angle of º.the solar radiation reduces towards the central part of the country. for example, ilorin the fourth city on the table has daily horizontal irradiance of . kwh/m and . kwh/m at optimal inclined angle of º. the lowest solar irradiance was recorded at the far south in port current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january harcourt with . kwh/m a day at horizontal and . kwh/m a day at optimal inclined angle of º with corresponding generation of , kwh and , kwh respectively. considering the worst scenario when the generating capacity was minimum, solar pv modules with % conversion efficiency in hectare ( , m ) surface area will generate a total annual energy of . gwh. . wind energy wind energy exploration in nigeria has not been significant as most of the existing wind energy systems are abandoned due to inappropriate evaluation of its potentials, operations and management [ ]. given the inadequate and epileptic power supply being experienced in the country, using wind energy conversion system to supplement the energy obtained from the serving hydropower and thermal power plants will be a wonderful initiative. however, given the huge initial investment capital, the government could encourage many individual users to adopt it by giving adequate incentives, such as feed-in tariff. with the current deregulation of the power industry in nigeria, the council for renewable energy in nigeria (cren), whose responsibility, among others, is to coordinate renewable energy development and implementation plan for the country, was created by the government [ ]. . . wind data collection and analysis lots of research works [ - ] have been carried out on assessment of wind energy potentials spread across the six geo-political zones in nigeria. these works were studied and the wind data used in the present study were obtained from [ - , , , ], most of which originated from the nigeria meteorological services (nimets) oshodi, lagos, spanning a period of years. it was observed that there is a wide disparity in the values of wind speed of certain sites as presented in different literature. however, the disparity may be due to year difference and height of wind data collection. while some authors standardised their data to m above the sea level, some presented theirs at different heights. to this end, the sources of the data used in this work are as indicated in table to pre-empt any unnecessary confusion. the entire country is divided into six geo-political zones. generally, the northern parts of the country are windier than the southern parts. based on the available data from literature, the north-west has the highest wind speeds which range from . m/s to . m/s at yelwa and kano respectively. this is followed by north-east zone having jos leading the zone with a wind speed of . m/s. in the south-east of nigeria, we have wind speed data for only two sites: enugu and ogoja having . m/s and . m/s respectively. for the south-western part of the country, the least obtainable annual mean wind speed is . m/s at ondo and the highest of above . m/s in cities like lagos island, lagos mainland and shaki. in the north-central geo-political zone, minna is found to have the highest with a wind speed of . m/s while bida has the least of . m/s. lastly, the south-south zone records the highest wind speed of . m/s at calabar while port-harcourt has the least wind speed in the zone with a value of . m/s. generally speaking, with most parts of nigeria having an average wind speed of . m/s shows that wind energy is viable in the country. . . estimation of wind power potential to estimate the potential of wind energy at a particular site, three parameters are usually required: the cross- sectional area of the turbine blade (a), the site air density (ρ) and the wind speed (v). thus the power available in the wind can be obtained through the expression in equation ( ). ⁄ ( ) in ( ), ρ is the air density at sea level normally given as . kg/m with variation of - % due to changes in atmospheric temperatures and pressure. a is the area swept by the windmill rotor obtained in sq-m using the expression a πd where d is the diameter of the circular edge of the windmill blades and v is the wind speed in m/s. however, when little knowledge of the site data is known, estimation of the wind energy could be obtained using the capacity factor approach formulated in [ ]. capacity factor (cf) could be defined as the ratio of the actual power produced over a given period of time to the hypothetical maximum capacity of the wind turbine or any generating facility running full time at rated power [ ]. the expression for cf of the earlier mentioned method which is entirely based on rayleigh distribution is presented in equation ( ). . d p vcf r ( ) where pr is the rated power of the turbine the goal here is to find a simple way to estimate the cf when very little is known about a site and wind turbine. adopting this method, a commercially available wind turbine, neg micron turbine [ ], with rated power (pr) of kw, rated speed of m/s, cut in speed of m/s and rotor diameter, d, of m was used in this study. the annual energy estimation for each zone in kwh/y is presented in equation ( ). cfpawe r  ( ) current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january table : capacity factor and estimated annual energy output for the selected cities. zone city annual mean wind speed (m/s) at m height annual wind speed (m/s) at m height capacity factor estimated annual energy (mwh) south-west shaki . [ , ] . . , iseyin . [ , ] . . , lagos mainland . [ ] . . , lagos island . [ ] . . , ibadan . [ , ] . . , ijebu-ode . [ ] . . , oshogbo . [ ] . . ondo* . [ ] . . benin . [ ] . . south-south port-harcourt . [ ] . . calabar . [ ] . . , ogoja . [ ] . . , south-east enugu . [ , ] . . , oweri . [ ] . . north-west yelwa . [ ] . . , sokoto . [ , ] . . , gusau . [ , , , ] . . , kaduna . [ , , , ] . . , kastina . [ , , ] . . , zaria . [ ] . . , kano . [ , , , ] . . , north-central ilorin . [ , ] . . , bida* . [ ] . . mina . [ , ] . . , abuja . [ ] . . , lokoja . [ ] . . north-east bauchi . [ - ] . . , potiskum . [ , , ] . . , maiduguri . [ , , ] . . , jos . [ , ] . . , yola . [ ] . . , total , *cities where the annual wind speed is less than the cut-in speed of the chosen wind turbine table shows the potential cf for the selected cities of each zone together with their potential wind energy output. the result shows that all the selected cities having the cf of between . and . have good potential for electricity production. on the other hand, cities exhibiting above . cf are considered to have very good potential for electric energy production. it is observed that those cities in the south are mostly coastal areas that are directly influenced by the wind from the atlantic ocean. in this study, cities with cf of . to less than . are considered to be unsuitable for electricity generation. however, the wind speed in these areas is good for water pumping. also shown in table is the annual wind energy realised from each city reviewed in this study. overall, a total of , mwh wind energy is estimated per annum from the selected sites, which is quite appreciable. notwithstanding, it is pertinent to add that this figure is just a rough estimate as the approach adopted in this study is not one hundred percent accurate. . conclusion and recommendations . conclusion this paper has presented a critical review of the status of renewable energy resources currently available in nigeria, and the potential to utilise them in meeting the current energy crisis facing the country. the renewable energy resources examined in the study include biomass, hydropower, solar energy and wind energy and estimates on their potential energy production capacity were provided. traditionally, the fossil fuels that have been the major sources of energy in nigeria are oil and natural gas. the need to address the challenges of moving towards clean, reliable, secure and competitive energy supply prompted nigeria to develop a long term renewable energy masterplan for the country in . the main goal of the draft document among others is to reduce the projected energy use by % by and equally meet % of the country’s electricity needs with renewable energy sources by . current status and outlook of renewable energy development in nigeria, m. f. akorede, et al nigerian journal of technology, vol. , no. , january the review showed that the per capita energy consumption in nigeria is very low and grossly inadequate for sustainable economic development, and this is correlated with the high poverty level obtainable in the country. to aggressively address this lingering energy problem, two international atomic energy agency models were used to project the energy demand and supply structure of the country based on four scenarios. conclusively, with the vast renewable energy resources reviewed in this study, the national energy policy as well as the national renewable energy masterplan, nigeria is well positioned to up-scale the use of renewable energy to meet the current energy crisis and at the same time reduce her dependence on fossil fuels. however, it is pertinent to add that the energy plans drafted must be given the required urgent approval by the federal executive council to become a legal document, and must be properly and sincerely implemented. . recommendations despite their availability in reasonable quantities, renewable energy resources are grossly underutilised in nigeria. in the light of this scenario, the following recommendations are proposed: (i) even though the government via the nigerian electricity regulatory commission (nerc) has formulated a policy on feed-in tariff as it applies to renewable energy resources, you only read this on newspapers. it is imperative that nerc carries along and enlightens the major stakeholders and members of the public as well, on this policy to accelerate investment in renewable energy technologies. (ii) one of the major factors militating against the deployment of renewable energy in nigeria is lack of clear government policies. the government should provide adequate legal instrument for renewable energy development. (iii) though nigerian government has already established research and development centres in the six geo-political zones in the country, these centres should be adequately strengthened financially to support the shift towards an increased use of renewable energy. it is also pertinent to add that the energy commission of nigeria (ecn) should continuously monitor and evaluate the performance of these centres in terms of quality research outputs from them. (iv) efficient energy use and conservation of energy through energy saving bulbs, improved fuelwood stoves, efficient electrical appliances, etc, should be promoted by relevant government agencies and non-governmental organisations, to reduce the energy demand. 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[ ] m. f. akorede, m. i. mohd rashid, m. h. sulaiman, n. mohamed, and s. ab ghani, "appraising the viability of wind energy conversion system in the peninsular malaysia," energy conversion and management, vol. , pp. - , . http://geosun.co.za/wp-content/uploads/ / /solargis-solar-map-nigeria-en.png http://geosun.co.za/wp-content/uploads/ / /solargis-solar-map-nigeria-en.png http://geosun.co.za/wp-content/uploads/ / /solargis-solar-map-nigeria-en.png http://re.jrc.ec.europa.eu/pvgis/apps /pvest.php?lang=en&map=africa http://re.jrc.ec.europa.eu/pvgis/apps /pvest.php?lang=en&map=africa http://www.mesor.org/ http://photovoltaic-software.com/pv-solar-energy-calculation.php http://photovoltaic-software.com/pv-solar-energy-calculation.php http://www.renewablenigeria.org/ anti-cancer effects of vitamin c revisited research highlight anti-cancer effects of vitamin c revisited cell research ( ) : - . doi: . /cr. . ; published online january cell research ( ) : - . © ibcb, sibs, cas all rights reserved - / $ . www.nature.com/cr npg vitamin c was first suggested to have cancer-fighting properties in the s and has been the subject of controversy ever since. despite re- peated reports of selective cancer cell toxicity induced by high-dose vitamin c treatment in vitro and in mouse models, the mechanism of action has remained elusive. yun et al. [ ] have recently shed light on what was until now the elusive mechanism by which vitamin c (aka ascorbate) induces toxicity in selected oncogene-driven cancers. they reported that in cells with mutations of kras or braf, death is not caused by vitamin c itself, but rather by its oxidized form dehydroascorbate (dha). whereas vitamin c enters cells through sodium cotransporters, dha competes with glucose for uptake through glucose transporters (particularly glut and glut ) and then is reduced back to vitamin c in cells [ ] (figure ). it was previously observed that while mela- noma cell lines take up dha at much higher rates than vitamin c, normal melanocytes do not, demonstrating that transformation-driven upregulation of gluts leads to increased uptake of dha [ ]. more recently, using mag- netic resonance spectroscopy imaging, it was demonstrated that hyperpolarized c-labeled dha is rapidly taken up by cancer cells and converted to vitamin c, illustrating the tumors’ reducing state [ ]. yun et al. [ ] now show that the reduction of dha back to vitamin c is at the crux of the vitamin c-induced cell death observed in these cancer cells. mutations in kras or braf are found in approximately half of the cases of colorectal cancer (crc) and their expression correlates with an increase in glut expression, glucose uptake and reliance on glycolysis. yun et al. [ ] observed that vitamin c is oxidized to dha in tissue culture media and that kras or braf mutated crc cell lines take up more dha compared to their wild-type counterparts. more impor- tantly, they found that dha induces death in the mutant lines, but not in wild-type counterparts overexpressing glut , suggesting that additional oncogenic reprogramming is necessary for dha-induced toxicity. the authors then profiled metabolic changes after treatment with vitamin c. in cells with kras or braf mutations, they found an accumulation of the glycolytic inter- mediates upstream of glyceraldehyde -phosphate dehydrogenase (gapdh) whereas those downstream of gapdh were depleted. this indicated a decrease in gapdh activity and a concomitant diversion of glucose into the oxida- tive phase of the pentose phosphate pathway (ppp), a metabolic shift that, upon oxidative stress, helps restore nadph levels and cellular reducing potential (figure ). indeed, yun and co-workers found that the intracellular reduction of dha back to vitamin c depleted the cellular stores of reduced glutathione (gsh, the major antioxidant in cells), leading to an increase in reac- tive oxygen species (ros). further- more, they found that, upon exposure to dha, gapdh itself was oxidized (on cys ), and consequently inhibited. inhibition of gapdh caused energy stress in the highly glycolytic mutant cell lines, leading to cell death. in mice harboring tumor xenografts with either kras or braf mutations, treatment with high doses of vitamin c reduced tumor size. treatment also reduced the number and size of polyps in an apc-driven transgenic mouse model of intestinal cancer, but again, only in tumors expressing mutant kras. more- over, in addition to showing the direct inhibition of gapdh by oxidation, the authors demonstrated that its activity is further hindered by dha-induced nad+ depletion, since gapdh activ- ity relies on the availability of nad+ as a co-substrate. the major nad+ consumer, the dna repairing enzyme poly adp-ribose polymerase (parp) was then investigated. it was found that the increase in ros after high-dose vitamin c treatment also induced dna damage and parp activation in kras or braf transformed cells. providing the cells with a parp inhibitor or an nad+ precursor partially rescued their viability. thus, ros cause the inhibi- tion of gapdh activity in cells on two fronts: first, via inducing its direct oxidation and second, by causing nad+ depletion (figure ). yun et al. [ ] thus demonstrated an intricate mechanism by which oncogenic reprogramming, which causes glycolysis addiction, in- duces a metabolic vulnerability which can be exploited with high doses of dha that elevate intracellular ros as it is converted back to vitamin c. despite numerous clinical studies, the anti-cancer property of vitamin c has remained controversial. potential translation of the mechanism presented by yun et al. [ ] to therapeutic applica- tion raises concerns regarding toxici- ties of high-dose vitamin c treatment. though the authors do not report side effects in their mice (treated daily with - g/kg body weight ip), the upper dose equates to over half a kilogram for the average person. high-dose cell research | vol no | march npg oral supplementation of vitamin c is associated with increased kidney stone incidence, and clinical studies demonstrated significant renal, cardiac, and metabolic toxicity upon vitamin c administration. still, overall reports of toxicity are variable, poorly graded, and therefore inconclusive [ , ]. affinity studies of dha for glut may help establish a lower effective dose, though unwanted side effects in tissues that highly express glut need to be con- sidered. the brain obtains vitamin c by uptake of dha through glut at the blood-brain barrier and its subsequent reduction [ ]. erythrocytes express high levels of glut and are crucial for ascorbate recycling, keeping dha levels low [ ]. importantly, erythrocytes rely solely on glycolysis for energy production. thus, high dha levels may induce brain toxicity and haemolysis via mechanisms similar to those described by yun et al. [ ]. though vitamin c oxidizes rapidly in tissue culture media, it acts mainly as an antioxidant in vivo. it remains unclear how and where circulating vitamin c is oxidized in vivo, an issue not addressed by yun et al. [ ]. oxidation of vitamin c to dha by tumor stroma has been suggested [ ], complicating the abil- ity to predict tumor responsiveness to the treatment. as such, without being able to control the extent of vitamin c oxidation to dha, effectiveness and toxicity of vitamin c treatment cannot be predicted. finally, the authors report that, fol- lowing dha uptake, nad+ depletion by parp activation contributes to the inhibition of glycolysis (and potentially to the stimulation of oxidative ppp flux). the observation that parp inhibition partly rescues vitamin c-treated cells may suggest that the toxic effect of dha uptake is not caused by ros alone, since restoring nad+ levels and glycolysis with the parp inhibitor may actually decrease ppp flux and nadph produc- tion, and aggravate the redox stress. it remains to be demonstrated that parp inhibition indeed restores nad+ levels in vitamin c-treated cells, and how this affects the balance between energy and redox metabolism. this also raises the question whether parp activity in brca / -deficient tumors produces a similar metabolic phenotype via nad+ depletion and whether the use of a parp inhibitor (e.g., olaparib) to treat these tumors [ ] might restore nad+ levels and counterbalance gapdh inhibition by other oxidative agents. in summary, yun et al. [ ] show that, in glycolysis-addicted kras and braf driven cancer cells, high-dose vitamin c treatment induces cell death via the up- take and reduction of its oxidized form dha back to vitamin c. dha reduc- tion, through scavenging gsh, induces oxidative stress, leading to gapdh inactivation, inhibition of glycolysis and the subsequent energy crisis and cell death. this study further elucidates the mechanism by which ros can in- duce cell death, and neatly shows how vitamin c, an antioxidant, can work as a double edged sword. however, further work is necessary to determine whether there is a therapeutic potential for vita- min c in cancer patients. jiska van der reest , eyal gottlieb cancer metabolism research unit, cancer re- search uk, beatson institute, glasgow, uk correspondence: eyal gottlieb e-mail: e.gottlieb@beatson.gla.ac.uk references yun j, mullarky e, lu c, et al. science ; : - . vera jc, rivas ci, fischbarg j, et al. nature ; : - . spielholz c, golde dw, houghton an, et al. cancer res ; : - . bohndiek se, kettunen mi, hu de, et al. j am chem soc ; : - . thomas ld, elinder cg, tiselius hg, et al. jama intern med ; : - . jacobs c, hutton b, ng t, et al. oncologist ; : - . agus db, gambhir ss, pardridge wm, et al. j clin invest ; : - . may jm. front biosci ; :d -d . agus db, vera jc, golde dw. cancer res ; : - . o’connor mj. mol cell ; : - . figure mechanistic overview of proposed vitamin c toxicity in crcs driven by kras and braf mutations. kras and braf mutations induce metabolic repro- gramming by upregulating glut , glucose uptake, and glycolytic flux. upon vitamin c treatment and its extracellular oxidation, dha (the oxidized form of vitamin c) is taken up through glut and is reduced back to vitamin c in the cells, depleting gsh and nadph. consequently, an increase in ros leads to gapdh oxidation, and with it, to a decrease in glycolytic flux. in parallel, ros-mediated oxidative dna damage induces parp activation and subsequently, nad+ levels fall and cause ad- ditional inhibition of gapdh and glycolysis, resulting in energy crisis and cell death. tdwt .. new combination of solar chimney for power generation and seawater desalination nayereh niroomand, majid amidpour* faculty of mechanical engineering, department of energy system engineering, k.n. toosi university of technology, tehran, iran tel. + ; fax: + ; email: amidpour@kntu.ac.ir received november ; accepted february a b s t r a c t in this article, a new combination of solar chimney and humidification–dehumidification desalination process is introduced. in this system, the air is humidified by injection of water drops into the air flow. then, the partial of vapors contained in the air is condensed on the outer surface of the cold water tubes. two mathematical models have been developed for a one-dimensional flow in the solo solar chimney and the integrated system. the performance of the integrated system including power and potable water production is estimated and the results are discussed. furthermore, it has been demonstrated that increasing in the tempera- ture and mass flow rate of humidifier inlet water would improve the performance of the integrated system. it is found that the increase in water production would cause the decrease in power output. also, to produce more fresh water, the number of dehumidifier tubes should be increased. keywords: solar chimney; power production; seawater desalination; humidifier; dehumidifier . introduction energy crisis and fresh water shortage are two issues which humans confront especially in deserted regions. fossil fuels are the most common fuels which are used to produce electricity and fresh water. as the usage of fossil energies has induced negative effects on the environment and nearly exhausted, a great interest has been devoted to use of the renewable energies to produce both power and fresh water. making use of solar energy as a clean energy, espe- cially in a sunny region, and setting up a combined model of solar chimney and desalination system can be a good choice to overcome the aforementioned problems to some extent. over % of the earth is covered by water but only % of all these sources are fresh water, and just less than % of fresh water is accessible for human direct use, so there is a great pressure on the fresh water resources [ ]. in recent years, human solved this problem by desalinating of brackish water. there are many methods for desalting salt water. in seawater desalination systems, both fossil fuels and renewable energies can be used [ ]. various studies have been done on the utilization of the solar energy among the renewable energies. solar desalination by humidifica- tion and dehumidification (hd) of air has been received considerable attention lately. several pilots of*corresponding author. - / - � balaban desalination publications. all rights reserved. desalination and water treatment www.deswater.com doi: . / . . ( ) – december design of energy-efficient buildings and benefits of enhancing reliance on natural lighting through maximizing the external reflected component journal of al azhar university engineering sector vol. , no. , october, , - design of energy-efficient buildings and benefits of enhancing reliance on natural lighting through maximizing the external reflected component a. m. saleh professional engineer (private sector) ملخص البحث يركز البحث على الفوائد العملية و الصحية للمستخدم نتيجة اإلعتماد على اإلضاءة الطبيعية داخل تصميم المساحات و يقدم البحث عدد من البيانات التخطيطية التى تمكن المصمم من تقدير . (erc)الداخلية بالمبانى بإستخدام معامل . اإلضاءة الطبيعية إعتمادا بشكل رئيسى على معامل اإلنعكاس الخارجى و ذلك لجميع الواجهات و عند كل األدوار abstract daylight can be provided via windows and glazed doors, as well as via skylights and other forms of top lighting. these glazed openings are collectively referred to as "fenestration." the placement, design, and selection of materials for fenestration are extremely important and can tip the balance between a high performance and low performance building. fenestration impacts building energy efficiency by affecting cooling loads, heating loads, and lighting loads. visual comfort is strongly affected by the window location, shading, and glazing materials. well-designed windows can be a visual delight. but poorly designed windows can create a major source of glare. thermal comfort can also be compromised by poor fenestration design. poorly insulated windows add to a winter chill or summer sweat, while windows with low u-values keep glass surface temperatures closer to the interior air temperature, improving thermal comfort. in addition, east-west windows and unshaded south windows can cause excessive cooling loads. and although windows and skylights provide opportunities for natural ventilation, they must be designed to ensure a safe, secure, and easily maintained facility. the table below specifies the recommended minimum illumination levels. any shortage in meeting these levels should therefore be supplemented via artificial means. according to hofman in his textbook handbook of lighting design, the table below (table ) provides a summary of the minimum illumination levels measured in lux. the lx value indicated for each building use is the required illumination level needed to perform the specific task. the table also provides codes that should later be used by the designer in another table(s) to aid in the final selection of an efficient lighting source. the above steps should be carried out after completion of the daylighting analysis and design. in order to establish a complete, energy efficient, and sustainable lighting design, the designer must implement an integrated approach for the entire facility. this dictates consideration of both natural and artificial design elements withing the egyptian building code of lighting. . building performance a high performance, cost-effective, comfortably daylighted building requires the design team to practice integration as per the following points:  adopt a holistic design approach, where the building is viewed as a whole and not just a collection of parts. common practice often fails to address the critical interactions design of energy-efficient buildings and benefits of enhancing reliance on natural lighting through maximizing the external reflected component between the building façade (which admits heat and light) and the electric lighting system, resulting in an uncomfortable and inefficient building that is expensive and difficult to maintain.  share appropriate decisions across disciplines.  regularly evaluate decisions for any building wide ramifications. table - guide values for illuminance e for various areas of activity in accordance international standards . occupant performance studies indicate that well-designed daylighting is associated with enhanced student performance, evidenced by % to % higher scores on standardized tests, while poor natural + artificial design of energy-efficient buildings and benefits of enhancing reliance on natural lighting through maximizing the external reflected component daylighting design has been shown to correlate with reduced student performance. the study confirms that it makes sense that students and teachers perform better in stimulating, well-lit environments. it provides evidence that daylighting can provide high quality light, stimulating views, and an important communication link between the classroom and adjacent spaces. fig. - gentle, diffuse daylight permeates a classroom with both sidelight and toplight. note that all surfaces are painted white to distribute light more efficiently and reduce contrast glare . energy savings daylighting can save energy and reduce peak electricity demand if electric lights are turned off or dimmed when daylight is abundant. according to a study conducted in the united states, k- schools spend more than $ billion a year on energy ( ) . daylighting, however, saves no energy unless the electric lighting system is appropriately controlled. to be effective, daylighting must be thoughtfully designed, avoiding glare and overheating, and must include dimming or switching of the electric lighting system, preferably with automatic photocell control. daylighting is the use of light from the sun and sky to complement or replace electric light. appropriate fenestration and lighting controls are used to modulate daylight admittance and to reduce electric lighting, while meeting the occupants' lighting quality and quantity requirements. daylighting is a beneficial design strategy for several reasons, until recent years most workspaces were lit by tungsten or fluorescent lamps, with high- pressure discharge lamps sometimes being used for sports-related and industrial buildings that require additional lighting. but newer compact metal halide and high-pressure sodium lamps with good colour rendering characteristics are now being used in offices and shops, particularly for decorative or display lighting. the development of „energy-efficient‟ lamps, in addition to the availability of a wider range of luminaire designs, has made possible very significant energy savings in general purpose lighting and has brought extreme lighting effects within reach of relatively modest budgets. the table below provides examples of some of today‟s lighting sources available in the market: . egan, m. david and olgay, victor w.; "architectural lighting", mcgraw-hill, nd edition, design of energy-efficient buildings and benefits of enhancing reliance on natural lighting through maximizing the external reflected component the table above provides basic general data of different lamp illumination levels and corresponding life spans. this was an effort which was later analyzed further by dr. philips in the following page in order to assess each type of lamp efficiency measured in (lm/w), in addition to general data such as rated average life, and colour temperature (k). table - list of artificial light sources lamp w tungsten lumens/w hours w mm fluorescent w mm fluorescent w compact fluorescent w low pressure sodium w high pressure sodium w led bulb table – lighting sources and corresponding lifespans and energy dissipation design of energy-efficient buildings and benefits of enhancing reliance on natural lighting through maximizing the external reflected component in order to realize considerable cost/energy savings, the designer must carefully select a combination of artificial lighting sources from the list above, to cover the deficit from natural lighting. one of the problems has been in the „cheap energy policy‟ of governments; there may be other good reasons for this, but it has led in the past to excessive use of cheap energy, and it is only recently, with a looming energy crisis, that governments have woken up to the vital need for savings to be made. the first line of defence must be in avoidance of waste; particularly a situation when a building with every light burning in the middle of the day when daylight is quite adequate, or after dark when the building is largely unoccupied. dr. philips argues that the total amount of energy wasted on a daily basis may not have been calculated, but it is considerable and equals the amount of savings which can be made in other ways ( ) . he provided the example of a transport building where artificial light is used all day irrespective of the level of daylight. there is no doubt a need for the level of daylight never to drop below the statutory design level, but this can be solved by adopting a system of control which links artificial light to the available daylight to ensure that the design level is maintained, whilst allowing significant reductions in the use of artificial light, which can be off for most of the day. references . mardaljevic, john and kevin lomas, ``creating the right image,'' building services / the cibse journal, vol , no. , july , pp. - . . philips, derek, with gardner, carl. “daylighting, natural light in architecture”, architectural press, oxford, . . hofmann, harald, “handbook of lighting design”, erco leuchten, berlin, . . egan, m. david and olgay, victor w.; "architectural lighting", mcgraw-hill, nd edition, . risk and ruin: enron and the culture of american capitalism. by gavin benke. university of pennsylvania press. . pp. £ . /$ . . reviews and short notices medieval citadel of the saxons: the rise of early london. by rory naismith. i. b. tauris. . xx + pp. £ . . in this comprehensive, learned and above all engaging book, rory naismith traces the story of london from its birth under the romans to the end of the eleventh century and the brink of its apotheosis as england’s capital. from the outset, london has always been an odd man out among english towns; londinium was neither the capital of a civitas, nor a colonia of roman citizens, nor even a municipium, but ‘a civilian mercantile centre’ (p. ), linking the commercial network of the north sea with the heartland of the roman province of britannia. but just as londinium’s rise was fuelled by commerce, so its decline and eventual collapse was related to the contraction of the trading network on which it depended; by the mid-fifth century it was ‘still surrounded by sturdy walls . . . containing a deserted, overgrown and at times boggy expanse punctuated by crumbling ruins’ (p. ). when, in the seventh century, a new commercial network was established, london was resurrected as lundenwic, outside the roman walls to the west, on the site still called ‘the old wic’ (aldwych). although by this time the town lay within the kingdom of essex (which at the time included surrey, parts of what would become hertfordshire, and all of what became middlesex), its regeneration is as likely to lie in the entrepreneurial skills of the merchants who frequented it as in the actions of any king. london, of course, was never just a trading centre. the wealth it generated attracted the attention of the rulers of britain, and before the end of the first century, londinium was ‘the preferred seat for the governor and his administration’ (p. ). the same was true of lundenwic, which (unlike other incipient urban centres in southern england) lay in ‘everyone’s border-zone’ (p. ), and was thus both exploited and patronised by the kings of kent, wessex and mercia as well as of essex. under these competing interests, lundenwic flourished throughout the eighth and into the ninth century. the old walled city, however, had not been entirely forgotten, at least in what remained of the western empire; gregory the great had intended it to be the site of the metropolitan bishopric. the politics of the early seventh century meant that that honour went to canterbury, but in london became an episcopal see, and though nothing remains of the first cathedral of st paul’s, it is assumed to lie beneath its successor, on ludgate hill. apart from this, resettlement within the walls began only in the ninth century, and has been attributed to king alfred ( – ), though in fact it c© the author(s). history c© the historical association and john wiley & sons ltd http://crossmark.crossref.org/dialog/?doi= . % f - x. &domain=pdf&date_stamp= - - reviews and short notices may have begun before his time, and was still ‘a work in progress’ when he died (pp. – ). on alfred’s death, only the area between cheapside and the north bank of the thames had been resettled, but the tenth century saw the city expand northwards towards its walls, while on the south bank, southwark was flourishing in the reign of alfred’s successor edward the elder. the city was also developing its own character and institutions. the peace-guild of london, which enforced the legislation of king Æthelstan as well as its own local customs, and the cnihtengild, which perhaps had military functions, both appear in the tenth century, and the court of husting in the early eleventh. the city also became increasingly involved in royal government, not only as a meeting-place for royal councils, but also as the centre for production of the coinage for which the west saxon kings are justly famous. london not only had more moneyers than any other english town, but by the early eleventh century was also producing the regularly issued dies which every moneyer had to use. its prominence is clear in the contemporary chronicle for the reign of Æthelred unræd ( – ); indeed Æthelred, who was crowned at kingston-upon-thames, and buried in st paul’s, has almost as much right as alfred to be regarded as london’s founding father. from his time onwards, the history of london and the history of the kingdom are inextricably intertwined; to tell one is to tell the other. the wealth and the self-confidence of london’s citizens enabled them to survive both the danish and the norman conquests; immigration has always been london’s life blood, and it was able to accommodate danes, norwegians, normans, frenchmen and flemings, while remaining essentially an english city. the surviving physical witnesses to london’s past are listed in an appendix, and their number is quickly enumerated. this is not surprising to elderly londoners like myself, who can scarcely recognise among the ever-taller buildings shooting up from the graves of their predecessors the town we knew as children. for this reason rory naismith’s ability to conjure up london’s earlier incarnations is not the least remarkable achievement of this remarkable book. to achieve this feat he narrowly interrogates all the available sources, archaeological, historical and numismatic, which (as he says at the outset) are ‘only useful if they are put together in the right way’ (p. ). his skills are amply demonstrated on every page, for instance in his discussion of the composite text known as iv Æthelred, an amalgam of monetary legislation of (probably) the tenth century and a list of market dues updated at some time in the late eleventh (pp. – ), or his exposition of the ‘two emperors’ coinage issued in the names of alfred of wessex and ceolwulf of mercia (pp. – ). equally striking is his evocation not only of london as a place, but of london’s people, such as imma, the northumbrian thegn ransomed from lundenwic’s slave-market (pp. – ), bishop waldhere, caught between a rock and a hard place, and desperately seeking advice from his archbishop (pp. – ), Ælfheah stybba and brihtnoth odda’s son relaying the decrees of king Æthelstan to the london peace-guild (p. ), and ansgar the staller rallying the forces of london against the advancing army of duke william of normandy (p. ). it is the combination of attention to detail, clear and concise exposition, and narrative force which makes this book not only an original and illuminating work, but also a pleasure to read. independent scholar ann williams c© the author(s). history c© the historical association and john wiley & sons ltd medieval silver, butter, cloth: monetary and social economies in the viking age. edited by jane kershaw and gareth williams. oxford university press, . xvi + pp. £ . . this book is a collection of essays based upon a series of symposia on the viking age economy. it builds upon the two earlier publications by james graham-campbell and gareth williams, silver economy in the viking age ( ), and james graham-campbell, søren sindbæk and gareth williams, silver economies, monetisation and society in scandinavia, ad – ( ). in this monograph, the social and ritual roles of silver in practices such as hoarding, fragmentation and the conversion of coins into jewellery are discussed. other economies are also explored, such as the commodity-currencies of butter and cloth. there are four main themes running through this volume, two exploring the function of silver in different economies within the viking diaspora, and two examining the non-monetary functions of precious metals and commodity economies. within this book, there are two chapters that examine the use of silver in viking age ireland. andrew woods paints the coinage of ireland in a new light, demonstrating that the debasement of hiberno-scandinavian coinage was not connected to failures at the mints. he discusses the lack of correlation between the kings of dublin and ireland and the renewal of the hiberno-scandinavian coinage. re-coinage appears to have been economically driven rather than coinciding with the accession of a new king. this leads him to conclude that the ‘perception of inferiority’ (p. ) of coinage in ireland has coloured the way in which it has previously been interpreted. it is interesting that political events, such as kingly succession or conquests in ireland, did not affect the coinage of dublin. in his chapter john sheehan reflects on the role of silver in ireland and how it was used by the kings in relation to the church. sheehan uses hoard evidence to demonstrate that the period in which the kings of clann cholmáin were the wealthiest coincided with high levels of church patronage. two chapters focus upon the fragmentation of silver objects and coins. in a re-examination of hoard evidence from scandinavia and the western baltic area, marek jankowiak concluded that there are many regional variations in the fragmentation of silver. in general, however, fragmentation occurred in conjunction with long-distance trade transactions. the patterns discernible from dirham fragmentation indicate that the scandinavians consciously selected heavier coins. mateusz bogucki explores the reasons for silver fragmentation as an economic activity. using the early eleventh-century mózgowo hoard from poland as a case study, he examines whether the available hoard evidence is representative of all viking age silver. scientific methods of analysing the silver content of viking age artefacts are constantly developing. guillaume sarah and stephen merkel discuss the latest methods of fingerprinting and ‘provenancing’ early medieval silver. while both sarah and merkel discuss numerous different non-destructive techniques available for analysing silver, the varying results lead merkel to conclude that the taking of ‘samples destructively is almost essential for provenance studies’ (p. ). sarah concludes that meaningful provenance studies stem from interdisciplinarity. in order to assess the provenance of a silver artefact, accurate metallurgical data needs to be gathered, but this information can only c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices be deciphered if enough historical, archaeological, geological and geochemical evidence is identified. florent audy provides a fascinating overview of the use of coins as pendants in viking age scandinavia. he discusses the multifaceted reasons why a coin might be worn as an item of jewellery, from functioning as a display of christianity, to demonstrating international connections and wealth. coins were socially and culturally significant, not just their precious metal content. gitte tarnow ingvardson provides a re-evaluation of the six mixed silver hoards from bornholm in denmark. she discusses how motives for the deposition of silver hoards were dependent on the individual, but can be used to understand better the economic, social and political organisation of bornholm. her methodological approach could be applied more generally to the study of other viking age hoards to demonstrate regional variations of hoarding practices. jacek gruszczynski also presents a new methodology for assessing the motive for hoard deposition. using case studies from gotland and pomerania, gruszczynski suggests that if a hoard was buried within a container then it was intended to be recovered. it is important, however, to note that he acknowledges that his theory is still evolving and the ‘deposition and non-retrieval of viking age hoards cannot be explained by a single grand theory’ (p. ). jane kershaw discusses gold as a means of exchange in scandinavian- controlled areas of england. she uses archaeological, numismatic and historical evidence to conclude that gold was used more widely as a form of payment than previously suggested by scholars. the number of hack-gold and gold ingot finds in england, as well as evidence for the testing of the gold, suggests that it was used as a transactional medium in parts of england. ester oras, ivar leimus and lauri joosau also focus on gold as a medium of exchange in the viking age. the discussion on the late ninth- to early tenth-century hoard from essau in estonia brings this unique and fascinating hoard of gold pendants to a wider audience, previously only published by local researchers in estonian magazines and journals (tuna and the estonian journal of archaeology). this hoard provides invaluable evidence for swedish vikings travelling in the old rus regions. svein gullbekk provides an overview of how the church in scandinavia collected money through offerings, tithes, taxes and dues, donations and fines in the late viking age and in the early medieval period. the church created a ‘spiritual economy’, whereby money could be used to expunge sin. gullbekk concludes that coins had moved from a means of payment to a means of salvation in the period of christianisation in scandinavia. the final two chapters of this volume discuss commodity-economies in iceland and the orkneys. michèle hayeur smith examines the use of cloth currency in iceland, and in particular focuses on the physical properties of vaðmál. smith argues that cultural and economic norwegian traditions arrived in iceland with the norse settlers and commodity-money came into use in early viking age iceland. the decline in access to silver is likely to have resulted in cloth being used as a basic unit of measure and value. aaron j. critch, jennifer f. harland and james h. barrett examine archaeological evidence from quoygrew, orkney, to discern if there is any evidence of a butter economy in the late viking age and the medieval period. zooarchaeological evidence suggests that cattle and sheep c© the author(s). history c© the historical association and john wiley & sons ltd medieval were more common in the region than other forms of livestock. additionally, the high number of calf bones indicates that dairy farming was important and butter production highly likely. historical sources specify the importance of butter as an export commodity as well as detailing ‘butter skat’ as a form of mandatory tax. silver, butter, cloth: monetary and social economies in the viking age explores the character of the viking age economies from archaeological and numismatic perspectives, and is accessible to any scholar with an interest in the viking age (c. ad – ). the main focus of the book, however, is the viking age silver economy. while other non-monetary commodities such as butter and cloth are discussed, it remains difficult to trace these eleventh- and twelfth-century practices back into the late viking age without further documentary evidence. nevertheless, this book is a fine collection of thought-provoking essays that challenge the idea that only silver was used as a means of exchange in this period. additionally, the breadth of geographical locations covered by the articles in this book is to its credit. this collection of essays provides a survey of new thinking about commodity-money and an informative overview of the viking age silver economy. university of east anglia johanne porter inauguration and liturgical kingship in the long twelfth century: male and female accession rituals in england, france and the empire. by johanna dale. york medieval press. . xvi + pp. £ . . british historians working on england in the central middle ages sometimes tend to assume that england is inherently different from a homogeneous mass labelled ‘the continent’. at best, normandy had been so deeply absorbed into the insular political orbit that it became an honorary part of england. elsewhere in europe, historians lacked the wealth of administrative sources associated with the island kingdom, and instead had to deal with ephemeral topics like ritual and symbolism, which were of no relevance to their more level-headed insular counterparts. worse still, french and german scholars possessed the temerity to write in languages other than english. johanna dale provides a magisterial corrective to this anglocentric approach. her book heralds a new generation of scholars, who, building on the work of david bates, tim reuter, nicholas vincent and others, seek to place the english experience firmly in a broader european context. her approach is both facilitated and complicated by the materials at her disposal. drawing on coronation ordines, narrative sources, judicial statements, letters, charters and seals, dale inevitably has to deal with fundamental methodological challenges. ordines, for instance, purported accounts of a coronation, were not only the result of closely entwined textual traditions, but are also almost impossible to link to any particular inauguration ceremony. likewise, as dale points out, almost four times as many charters survive for the reign of henry ii of england (r. – ) as for his contemporary frederick barbarossa (r. – ), and they follow a rather different structure and design from that of their french and german counterparts. and then there was, of course, the problem that, in the german c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices case, inaugurations related not only to the enthronement of kings and queens, but also to the papal ceremonial of an imperial coronation. it is testimony to dale’s considerable abilities as a historian that she not only recognises these differences, but instead uses them to make the case for comparison. as she puts it, the same instrument can be used to play very different tunes. the result is an eminently readable, rich and subtle book to which it is impossible to do justice in a short review. there is just so much to recommend: how dale traces the subtle variations and shifts over time between coronation ordines; her accounts of the saints invoked and the liturgical emphases placed; her masterful discussion of the importance of dates and their liturgical connotations not only for the inauguration festivities themselves, but also for the dating of charters; how skilfully she disposes of assorted historiographical shibboleths; the assured handling of a rich body of scholarship in english, french and german; and the sheer wealth of insightful and astute observations, as well as the vast range of materials consulted. dale successfully tackles the myth that the hildebrandine schism (or investiture contest) had a profound impact on the development of royal sacrality; shows how different liturgical elements and prayer formulae could nonetheless be used to express subtle shifts over time or between occasions; and perceptively discusses the role of tradition in picking coronation dates, while simultaneously taking to task a sometimes overly simplistic modern emphasis on coronation regalia. the decision to complement the liturgical materials with a discussion of charters and seals was inspired. both amplified and reiterated the liturgical dimension of kingship, though to degrees that could vary considerably between the component realms. the relevant chapters reinforce another central argument of dale’s: that the significance of the inauguration was not limited to the event itself, but was continuously referred back to and invoked in the practice of royal lordship. the overall image that emerges is one where the sacrality of kingship inevitably manifests itself differently in each of the realms studied, but where these variations were ones of degree, not evidence of fundamentally different political cultures. in the english case, for instance, liturgical kingship was amplified by, rather than standing in opposition to, the bureaucratic tools at the disposal of kings, while, for much of the period, capetians kings were followers of fashion rather than its originators, and german rulers carved out a distinct ceremonial emphasis depending on who was crowned and who did the crowning. the genre of a book review requires that at least some criticisms be voiced. more could, for instance, have been done with the english practice of making the actual inauguration dependent on the candidate promising to abide by basic norms of royal lordship. as dale points out, there was no equivalent to the english coronation oath in france and germany. with the emphasis on the twelfth century, there is a danger to assume a formalised selection of inauguration sites, for instance, that only really emerged in the second half of that century. and there is, of course, the problem that england, france and germany were among the few realms for much of the twelfth century where coronation and unction were both practised. they were still the exception, not yet the norm. even so, these are also relatively minor quibbles. some are simply a matter of different historians placing different emphases, and others would have required dale to write a very different book from the rather splendid one she has. suffice it therefore to conclude by stressing just how important, innovative and insightful c© the author(s). history c© the historical association and john wiley & sons ltd medieval a study this is. dale has made a major contribution to our understanding of kingship, political culture, and the interplay between the sacral and the secular in medieval europe. hers is, in fact, one of the most important books on the subject to be published in the last thirty years. it heralds the arrival of a major new voice in medieval studies. university of aberystwyth björn weiler justice and mercy: moral theology and the exercise of law in twelfth-century england. by philippa byrne. manchester university press. . xviii + pp. £ . . felony and the guilty mind in medieval england. by elizabeth papp kamali. cambridge university press. . xv + pp. £ . . once again illustrating the london bus principle of academic publishing, after a long wait along come not one but a brace of monographs both devoted to the same basic phenomenon. in this instance the pairing is serendipitous rather than repetitive. the bus’s route was first mapped long ago, by thomas green’s verdict according to conscience ( ), then by james q. whitman’s the origins of reasonable doubt ( ). green and whitman traced the influence over jury trial by a theology that emphasised the twin perils of uncertainty and false judgment. as byrne and kamali now demonstrate, in an age in which doubt was the natural correlative of faith, not only was truth hard to establish, but a failure properly to do so might result in injustice; itself an encouragement to criminal behaviour, threatening the eternal damnation not only of the criminal but of judge and jurors. byrne approaches her subject from a theological standpoint, kamali via the routine of judges and juries. byrne’s chief authorities are seneca, abelard, peter the chanter and all those others, including the english chroniclers, seeking means both to define moral responsibility and to ensure that justice might be tempered by mercy. this was a task rendered all the more urgent after when the abolition of ordeal by fire or water in criminal trials obliged english courts to turn decision-making over to juries previously used in such cases merely to present the court with evidence or suspicion of criminal behaviour. kamali, tracing this pre- evolution more briefly, is chiefly concerned by what happened next. using an impressive range of sources – administrative, jurisprudential and literary – she supplies a definitive survey of the means and devices by which juries struggled to dispense justice in criminal cases, over the century after . arguably her greatest achievement is to obtain certainty where even maitland was inclined to fudge. thus she demonstrates that ‘felony’, a term maitland assumed to be undefinable save by the severity with which it was punished, was itself derived from what was ‘fell’ or ‘bitter’ (from the latin ‘fel’ for gall, as first suggested by sir edward coke). via a path winding through literary pastures, besides the not so still waters of medicine and humoral theory, kamali proves that ‘felony’ implied felonious intent and therefore deliberate or premeditated wrongdoing: in legal terms ‘mens rea’, or guiltiness of mind. both authors are commendably keen to define words. thus byrne shows that mercy (‘misericordia’) was a concept enriched by and to some extent superseded by the roman-law term ‘aequitas’, or equity, long before . in both books, c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices ‘tutus’ (adjective) and ‘tutamen’ (noun), in the sense of security for defendants, justices and jurors, prove significant. so too does ‘discretio’: the obligation or justification to dispense from strict adherence to the law. yet discretion opened the way to injustice, especially in cases of felony where there was no real spectrum of punishments between death and acquittal. byrne begins with the age-old question ‘what is justice?’, i.e. is ‘justicia’ retributive, or a more abstract concept of righteousness, punishment for the body or medicine for the soul? as this in turn implies, both books are clearly written, using technical but jargon-free language, accessible to specialists and non-specialists alike. byrne’s authorities in theory, and kamali’s justices and jurors in practice, resolved various dilemmas by opting for acquittal rather than conviction in cases where it was difficult to sift lies from truth. in this, as byrne shows, they followed the best classical authorities from sallust to ambrose. here, although we are offered a conspectus of stories from scripture, notably the contrasted cases of phinehas, susannah and pilate, we might have heard rather more about the devil as the ‘father of lies’ (cf. john : ), as about doubt itself (‘dubium’) as a concept present in scripture and hence in later scriptural commentary. the gospel of luke ( : ) refers to those ‘tardi corde ad credendum’, as elsewhere the story of doubting thomas exalts those who believe without demanding firm or physical proof. all of this in a world where physical proofs were hard to come by, yet firm decision- making (then as now) remained essential for the common good. there will one day be a more accurate statistical analysis of the rates of acquittal in felony cases, over time, over type of offence and over geographical range. we may also question the composition of crown-court juries (freemen all, but of what relative status?) and the extent to which judicial intimidation of jurors is hidden from us before the age of independent court-reporting. what is certain here is that both writers challenge various comfortable assumptions, rewriting english law as a history not simply of writs but of complicated ethical choices. they suggest that medieval law did not, as various modernists might suppose, strive after brutally simplistic or mechanistic outcomes but allowed free and often troubling range to human conscience. despite the long-held belief in english exceptionalism, and the assumption that england was a land spared torture or inquisition, both byrne and kamali reveal the strong parallels to be drawn between inquisitorial and english procedures, especially in the english coroner’s court, in the interest shown in accomplices (in heresy trials ‘fautores’), and in the emphasis upon backsliding or habitual wrongdoing as a swift and certain route to gallows or pyre. in all such cases ‘fama’, or reputation, remained crucially significant, as in a ‘confessing society’ did the compulsion to probe motive and intent. english law did indeed diverge from its continental archetypes, but that divergence was both slower and more subtle than some are inclined to admit. behaviours, human impulses, perhaps even judicial procedures, alter rather less over time than the terminologies used to describe them. these are both fine books, brim-full with learning. they promise a bright future not only for their authors but for the ongoing study of medieval law. university of east anglia nicholas vincent c© the author(s). history c© the historical association and john wiley & sons ltd medieval the figure of minerva in medieval literature. by william f. hodapp. brewer. . xiii + pp. £ . . in the introduction to his new book william f. hodapp supplies a quotation from the twelfth-century poet, scholar and commentator bernard silvestris that underpins the author’s own response to the multiple different representations of the goddess minerva in medieval literature: ‘one must indeed remember in ... allegorical works, that there are equivocations and multiple significations and that one considers poetic fictions in diverse ways ... [t]he diverse aspects and multiple interpretations of poetic fictions must be observed in all allegorical matters if in fact the truth will not be able to stand in a single interpretation’ (p. ). in this rich, wide-ranging study hodapp demonstrates just how complex and multivalent the figure of minerva was in medieval english and scots literature. the roman goddess of strategic warfare, intellectual activity and practical arts, minerva was used by medieval poets both as a figure for wisdom and as a figure for wisdom applied to a particular craft or practice. thus, in her manifestation as a martial deity, for example, she was often distinguished from the more unruly or bloodthirsty prosecution of warfare characteristic of mars (ares in greek mythology). after providing a comprehensive introduction to the classical sources for representations of minerva, and her connections back to the greek pallas athena, whose origin myth saw her spring forth armed from the head of zeus, hodapp provides valuable intellectual context for the chapters that follow by carefully placing the goddess within traditions of medieval classicism and fifteenth-century personifications of christian wisdom. hodapp’s methodology in this book is to propose a fivefold paradigm for anatomising minerva’s imagery as it was used in fifteenth- and early sixteenth- century allegorical and dream-vision poetry. his focus is upon minerva as redemptress; mistress of the liberal arts; patroness of princes; idol; and as venus’s ally. in each case (with a chapter devoted to each tradition), hodapp introduces the particular aspect of wisdom under consideration, outlines the fundamental late classical and early medieval sources for each tradition, and then provides a series of case studies demonstrating how selected poetic texts take up and explore this facet of minerva and her representation. chapter examines the ‘sapiential’ tradition which cast minerva as a figure representing the redemptive wisdom that one finds through contemplation of god and the universe. literary exemplars of this tradition see minerva incorporated into versions of the judgement of paris story, as in john lydgate’s early fifteenth- century reson and sensuallyte, only for her (too) to be rejected in favour of venus. such a selection/rejection was employed in such cases as an instructive negative example, against which minerva – representing the correct decision, virtuous wisdom and the contemplative life – was contrasted. hodapp follows the sapiential tradition with discussion of the ‘martianus’ tradition in which minerva was the mistress and benefactor of learning and skill. rooted in the presentation of minerva as magistra artium liberalium in martianus capella’s fifth-century de nuptiis philologiae et mercurii, hodapp’s exposition of this tradition begins by considering moments where minerva’s patronage and the life of study contrasted with that devoted to mars and the ways of war. minerva appears as mistress of the seven liberal arts in the anonymous dream-vision the court of sapience and in john skelton’s garland of laurel. in the latter example, c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices minerva (as pallas) advocates for skelton’s dreamer when fame attempts to exclude him from her court. chapter examines minerva as a political figure: as a patroness of a city- state or prince. such protection operates on the individual level in the classical sources homer and statius, where the goddess watches over achilles and theseus (respectively) and assumes an armed presence. it is in this tradition that we see minerva represent the application of wisdom to the martial sphere, both in supplying strategic wisdom to those engaged in war, and when exercising judgement as to when not to fight and applying wisdom to the brokering of peace. hodapp traces minerva’s role as patrona principis in medieval reworkings of the troy story by joseph of exeter, guido delle colonne and john lydgate. attention then turns to christine de pizan’s l’epistre d’othea (c. ), in which the author invents the titular minerva-like wisdom figure as a means of advancing the case for the application of learning and good order to chivalric conduct. othea represents knowledge and prudence applied to the practice of arms; one manifestation of this hybridity is the euhemeristic reading of minerva as the mythical inventor of armour (p. ). hodapp concludes this chapter with stephen hawes’s early tudor dream-vision, the pastime of pleasure, which sees its hero, graunde amoure, educated in both the liberal and chivalric arts. the final two chapters move away somewhat from consideration of minerva as a representative of divine or practical wisdom. here the focus is, by turns, upon the goddess as an idol and as the ally of venus. in the former ‘patristic’ tradition, she is cast as a demon or as the application of intellectual powers towards wholly worldly concerns, as is found in the anonymous poem assembly of gods and william dunbar’s the golden targe. chapter takes a more positive approach and explores – despite the two goddesses being opposed in many different classical sources – the presentation of minerva as venus’s ally, here drawing on a subtle reading of one aspect of ovid’s metamorphoses and the conception of minerva as embodying the perfection of a craft or practice, in this case love. hodapp carefully traces instances of this facet of minerva in chaucer’s troilus and criseyde, james i’s kingis quair and charles d’orleans’s fortunes stabilnes. hodapp’s book provides a thorough introduction to the multivalent nature of minerva in both earlier and later medieval thought and literature. it is to be welcomed by scholars of medieval classicism, mythography and literature for offering the first book-length study of this figure and her multiple facets. grounded in extensive research, this book at each stage provides the reader with useful, not quite excursory expositions of concepts pertinent to the ongoing discussion. witness, for example, the sections on medieval wisdom literature (pp. – ), the origins of the liberal arts (pp. – ), idolatry (pp. – ) and the reception of ovid (pp. – ). on occasions when reading this book, one would have liked to have learned more about points of overlap or indeed conflict between the five traditions identified by hodapp. since his focus in this study is predominantly on literary examples drawn from allegorical and dream poetry, one can easily envisage subsequent scholars taking up hodapp’s lead and examining some of the different facets of minerva as she appears in other literary genres of this period, perhaps in relation to her representation in the contemporary visual arts or to her manifestation in sources from the later sixteenth century and after. university of east anglia matthew woodcock c© the author(s). history c© the historical association and john wiley & sons ltd medieval the anglo-latin gesta romanorum. edited and translated by philippa bright. oxford medieval texts. . cvii + pp. £ . . there can be few types of sources that provide a clearer window into a society’s mentality than fictional stories shared among contemporaries, both to entertain and to lay down ethical and theological guidelines. such is the anglo-latin gesta romanorum, a collection of moral tales (with a further eighteen in the appendix) gathered together in the fourteenth century, including some which were new, many which had been in circulation for centuries (i recognised a few which are included in william of malmesbury’s gesta regum anglorum) and some that date back to the classical period. this was an enormously popular source surviving in manuscripts. it was used initially by the clergy for preaching but subsequently came to be employed in a far wider range of contexts, later versions of the gesta remaining in popular circulation well into the eighteenth century. the gesta’s stories represent a fascinating assortment of myths, fables, theological lessons and quasi-sermons. in structure, each of the tales follows a standard pattern. they open by supplying the name of the emperor in power in rome at the time when the story was set. some of these emperors are recognisably from the historical record (e.g. tale is set at the time of the emperor titus), but in many cases the named ‘emperors’ are fictional or include either more recent individuals or those famous for other reasons. consequently, tale takes place at the time of the emperor ‘anselm’, tale at the time of fulgentius, and perhaps most remarkably tale is situated at the time of the emperor averroes (the famous twelfth-century islamic writer and theologian); a thought-provoking point for those interested in christian–islamic relations. after this introductory passage, a story then unfolds almost ubiquitously set in the contemporary present, following which there is a later section where the author explains the story’s moral and/or theological message. in content, the stories contain a vast array of insights on a wide range of matters. their basic purpose is nearly always theological or moral, but what makes them so interesting is that they are often set in unglamorous locations. so where the main ‘historical’ chronicles of this period focus their attention on mighty battles, treaties and church councils, the gesta romanorum is more interested in domestic affairs, relations within families, friendships, or conversations in taverns. consequently, there is a lot of coincidental detail about everyday matters that in other sources rarely receive much coverage. scholars interested in issues of gender especially will find a great deal to interest them given the sustained attention paid to marital relations and courtship. from a theological perspective, these tales are a gift to those interested in biblical exegesis and, more specifically, the way in which contemporaries were encouraged to live out their faith. these tales are earthly in their focus and they seek to show how specific christian teachings should influence an individual’s daily life. in this way, the gesta’s stories set out to provide contemporaries with an interpretative bridge connecting biblical scripture and lived experience. at times, the moral message is obvious after reading the first few lines, at times it is more obscure. for example, tale concerns a knight who saw a toad and a serpent doing battle. the knight struck down the toad, saving the serpent, but then later that night, the toad came into the knight’s bed and attached itself to his chest. the knight then suffered for a long time from the toad’s presence until he was saved by the serpent, who drew out all the toad’s poison. the moral of the tale c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices is that the knight – representing the human race – has a duty to fight the devil (the toad) and suffer his onslaught, but can have the firm expectation of healing and salvation from jesus christ (the serpent). the employment of animals as proxies for spiritual figures, ideas or vices/virtues is likewise common throughout this collection, providing a great deal of material for those concerned with the symbolism attached to different animal species. on a broader level, many of the stories are redolent of their broader fourteenth- century background, containing themes connected to social hierarchy, heresy, intellectual life and spirituality that will be of interest to anyone working on this period. for example, historians of the crusades and pilgrimage to the holy land will find it notable that several of these stories include journeys to the east, often in order to provide a narrative structure and purpose (i.e. character a goes away to the holy land and the story concerns characters b and c and what they get up to while the pilgrims are gone). likewise, several stories make brief reference to the ongoing wars between western christendom and egypt, reflecting the sustained struggle with mamluk egypt. there are only a few stories that discuss muslims (‘saracens’) directly, but tale (‘shooting at father’s corpse’) sets out the author’s view of the spiritual differences between christians, bad christians, jews and muslims. overall, this critical edition and translation of the gesta romanorum is truly a magnum opus. the translation of such a huge number of different tales – each containing a broad array of quite specific and technical terms – from the latin into highly readable english is a great achievement. the stories themselves provide illuminating windows into the structures of morality, the realities of existence and the rhythms of life that represent the beating heart of christendom’s collective consciousness. the fact that the stories were so popular only adds credibility to the idea that they can be taken as indicators of mainstream attitudes, rather than reflecting liminal or counter-cultural perspectives. nottingham trent university nicholas morton military society and the court of chivalry in the age of the hundred years war. by philip j. caudrey. boydell. . xii + pp. £ . . detailed records have survived for three of the armorial cases heard before the court of chivalry in late medieval england: richard, lord scrope v. sir robert grosvenor ( – ), john, lord lovel v. thomas, lord morley ( – ), and reginald, lord grey v. sir edward hastings ( – ). the testimony of about lay and ecclesiastical witnesses has proved a rich quarry for historians, but philip j. caudrey is the first to devote a book to exploring what this material, enriched by biographical and prosopographical research, reveals about patterns of military service, the web of social and political ties connecting the protagonists in these cases to their witnesses (and the witnesses to each other), and, more broadly, ‘the role of war-making and chivalric culture . . . in shaping the outlook and governing the daily concerns of england’s gentry’. building on and extending the research agendas of other scholars, caudrey develops three interconnected lines of investigation from which emerge new approaches to exploiting this corpus of evidence. the first considers the military careers of c© the author(s). history c© the historical association and john wiley & sons ltd medieval the witnesses, as revealed by their supplemented and enriched testimony. the author does not set out to supplant earlier work in this area; indeed, there is comparatively little ‘retracing of old ground’, particularly with regard to the pre- period. focusing on service undertaken from onwards, particularly by witnesses supporting grosvenor and hastings, he highlights areas of difference and contrast, such as the distinctiveness of the grosvenor witnesses’ service: their versatility and focus on garrison service. he also reveals what these two groups of witnesses, and indeed those supporting scrope and morley, had in common, perhaps most notably the frequency of family-level continuities of service into the reign of henry v. at least men in the agincourt army were descendants of militarily active court of chivalry witnesses: family traditions of military service, established under the edwardian kings, ‘remained alive and well in ’. fresh approaches to the court of chivalry witnesses and their testimony are to be welcomed (though the deployment of biographical case studies, intended to add nuance to our understanding of circumstance and motivation, adds little to the existing literature), but in this case the impact would have been greater had more careful and explicit attention been given to underlying contextual developments: that is, to the militarisation of the gentry from the s onwards, together with subsequent changes in recruitment patterns and the social profile of soldiers. a military careerist in the s inhabited a very different world from one operating in the s and s. the author’s handling of the detail of military affairs is also not free of error, the most persistent being the conflation of two campaigns in : men who served with john of gaunt in picardy and the pays de caux are assigned to the smaller-scale operations in gascony. and here and there, expressive exuberance leads to loss of control. the guy, lord brian who, we are told, ‘missed most of the picture book chevauchées of the high edwardian age’, actually accompanied the king to war, as a member of his household, on every available occasion from to – , being knighted at crécy along the way. second, and more substantially, caudrey explores the overlapping and complex roles played by lordship and regional ‘inter-gentry solidarities’ in the selection of witnesses and, thus, the shaping of testimony in these armorial cases. the deployment of the lancastrian affinity in support of scrope has long been recognised. here we learn how, for scrope, that support was amplified by genteel social networks, while for others the influence of lordship could be indirect. thus, hastings was reliant on those who had served with his father under john of gaunt, while scrope and morley benefited from the testimony of men who had been associated with the bohuns, the uffords and the prince of wales. caudrey’s absorbing analysis of the composition of the various groups of witnesses illuminates the armorial protagonists’ recruitment strategies, while demonstrating how, for scrope and morley, personal standing and their families’ distinguished war records enabled them to find witnesses beyond their principal regional support bases. this promising line of investigation could be taken further. first, there are the men who testified for lovel against morley. caudrey draws upon their distinctive testimony, but omits them as a group from his prosopographical enquiries because only sixty-two, out of well over two hundred, can be identified. but given that the testimony is complete for several of lovel’s hearings in march and april it is possible to examine the backgrounds and connections of coherent groups of witnesses. armorial identity could also be brought to bear on the matter. an exploration of our witnesses’ c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices own armorial identities, set within an ever more densely populated heraldic landscape that was animated by family-to-family armorial dissemination, often as a consequence of service connections, would offer an additional means of probing and substantiating vertical and horizontal social relationships within military society. caudrey’s third line of investigation explores the cultural context within which patterns of military service and the testimony of court of chivalry witnesses should be interpreted. he shows how chivalric memory – at once a complex fabric of many interwoven threads and a source of cohesion within regional military communities – was ‘expressed [in court testimony] through an intricate and interlocking combination of war recollections, family and regional history, and popular hearsay, augmented by a combination of written and iconographic material’. two themes stand out. one concerns the ‘battle of memory’ that resulted when deep-rooted traditions within regional military communities collided in the court of chivalry. vibrant oral tradition concerning a region’s great families, reinforced by material evidence, ensured that beliefs about ancient heraldic right formed a living part of regional, as well as family, identity, adhered to even in the face of overwhelming evidence to the contrary. second, it is argued that comparison of the testimony of the s with that of the s reveals how attitudes to military events had shifted over time. to witnesses in the mid- s, the – phase of the french war, which was fought attritionally and eventually to a standstill, lacked the lustre of success associated with the period prior to . by – , however, the campaigns of the stalemate years, now a distant memory infused with nostalgia, were viewed more positively. ‘these shifting attitudes’, notes caudrey, ‘may partly explain the enthusiasm with which the gentry . . . returned to arms in ’. caudrey brings subtlety and insight to the interpretation of the witnesses’ testimony, and yet more allowance could be made for the impact of interventions by court clerks and copyists on the texts that have come down to us. in scrope v. grosvenor, for example, the imprecise, formulaic character of the depositions taken down at plymouth, when compared with the records of other sessions, raises the suspicion that at best they provide a heavily abbreviated record of what was said. while affecting our understanding of patterns of military service in general, this has some bearing on whether hastings’s witnesses were actually more ‘celebratory’ about the campaigns of the – period than scope’s had been in the s. it is unfortunate that a number of pertinent and important publications appeared too late to be noticed or exploited fully by the author, for they can only have added weight to what is the most substantial and stimulating exploration of its subject to date. caudrey’s book demonstrates how taking a comparative approach to the witnesses and testimony of the three armorial cases serves to expand investigative possibilities within both the immediate locality of its subject and the broader research landscapes of military communities and noble–gentry relations. keele university andrew ayton c© the author(s). history c© the historical association and john wiley & sons ltd medieval constructing a civic community in late medieval london: the common profit, charity and commemoration. by david harry. boydell. . xi + pp. £ . . late fourteenth-century london was a turbulent place, epitomised by the anarchy and violence of the peasants’ revolt in . harry sketches this backdrop competently, then proposes that over the next century the response of london’s governing elite was to address the underlying dissent within the capital by controlling political language and its underlying ideology to legitimise their authority. this small elite possessed no hereditary rights to rule, so they established and communicated their authority through tighter control of political language and by convincing their fellow londoners that their rule was divinely ordained and in everyone’s best interests. they appropriated and sharpened the malleable concept of the ‘common profit’ to mean the pursuit of prosperity through participation in charitable activities, the exercise of spiritual authority and the preservation of harmonious relations. harry’s intention is to explore the mental world of the ruling elite of aldermen, mayors and their professional civil service, not their modes of governance, by analysing the administrative documents they generated. the governance of london is known to have become increasingly bureaucratic and interventionist during this period, and harry argues that this development corresponded with a reshaping of political ideology, in which civic office was sacralised: the elite received ‘homage and worship’ (p. ) from other citizens and in return it offered lavish charitable acts. foremost among the latter was the memorialisation of those leading londoners whose activities had swelled the common profit of the city, including the epitaphs of the exemplary dead. during the course of the fifteenth century, the elite adapted the notion of charity to include the production of religious literature and the growth of a textual culture through expanding access to manuscript and written books. hence the tiny elite who governed london nourished the city socially, economically and spiritually, and became very good at ensuring that everyone else knew it. the book focuses primarily upon the vernacular literature of fifteenth-century london, concluding with caxton’s printed works of the s. it is well informed by the existing scholarship in a range of disciplines, from political ideology (medieval and modern), literacy, religion and the economic history of london. the writing is fluent and accessible, and the argument is sustained and coherent. harry retains a salutary awareness of the typicality of the extant sources, reminding us regularly that these are mere remnants of a once significant london archive destroyed by the great fire. the result is an engaging, interesting and accessible scholarly monograph. st paul’s school, london, and the university of east anglia mark bailey inquisition in the fourteenth century: the manuals of bernard gui and nicholas eymerich. by derek hill. x + pp. boydell for the york medieval press. . £ . . to what extent was the inquisition against heresy institutionalised over the course of the fourteenth century? such is the principal question posed by derek hill. comparing and contrasting the two great procedural treatises written by c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices dominican inquisitors – bernard gui’s practica (a product of the southern french inquisition c. ) and nicholas eymerich’s directorium (emerging from the inquisition in aragon, but written in exile at avignon in , by a paris- trained professional who had twice clashed with the aragonese crown) – hill is obliged to enter a kafkaesque world in which orthodoxy was enforced by those determined to prove the existence of a prevailing heterodoxy. gui’s practica was last edited in and, despite six known manuscripts, failed to exert any discernible influence over later inquisitorial procedures save at second or third hand. as hill demonstrates, the edition itself obscured gui’s intentions by deliberately detaching gui’s list of contents from the materials that followed. by contrast, eymerich’s directorium circulated in at least thirty- five manuscripts and more than a dozen early modern editions, being widely taken up by later inquisitors, not least by the malleus maleficarum in which eymerich’s mostly masculine suspects are reclothed in the prevailing feminine terminology of witchcraft. the irony here is that the popular eymerich, himself last fully published in , drew very heavily on the (relatively unpopular) practica of gui. gui worked in close cooperation with the royal authorities in languedoc, not least in an effort to avoid the ‘carcassonne madness’ of in which the franciscan bernard délicieux had stirred up local revolt both against inquisition and against the authority of the french king, philip iv. by contrast, eymerich operated at best with the grudging support, at worst against the express interests of the aragonese king, pedro iv. in languedoc, where the kings of france drew profits from the confiscation of the property of heretics, there was a degree of cooperation between inquisition and local power structures lacking in aragon, where costs could not so easily be recouped from the inquisition’s victims and where eymerich’s campaign against sorcery created tensions with a royal court that was itself a major centre for astrology. eymerich’s belief in the immanence of demonic powers, derived in part from aquinas, in part from rhetoric first deployed by pope john xxii, contrasts with gui’s more single- minded pursuit of dualist heresy, which was by the s close to extinction in languedoc. where gui was reluctant to use torture (or at least to admit to its use), eymerich embraced it as an essential means of dispelling doubt. at the same time, by acknowledging that, through their demonic powers, the tortured might continue to deny or muddy the truth, eymerich applied a further turn to the screw by which suspicion was twisted into full-blown paranoia. troubled by the inquisition’s tendency towards autonomy, as early as , pope clement v had attempted to introduce a degree of episcopal oversight. gui’s reasoned response here (itself still unpublished, although surely deserving edition) can be contrasted with eymerich’s more strident emphasis upon the majesty of inquisition. this, as hill demonstrates, was rendered more rather than less autonomous by an appeals process that would have been inconceivable to gui. such appeals, under eymerich frequent and regularised, were themselves incorporated within an inquisitorial ‘system’ that, as a result, now slipped even further beyond ordinary episcopal control. where gui had employed his sermones generales (medieval forerunners of the later autos-da-fé) as public displays of the reconciliation of the repentant and the punishment of the incorrigible, focusing upon essential points of faith and the particular circumstances of languedoc, eymerich’s vision of heresy extended from the local and particular to pretty much any deviation from what he was prepared to define as orthodox. in the process, he reached c© the author(s). history c© the historical association and john wiley & sons ltd early modern far beyond essential points of doctrine to denounce blasphemy, magic and what was now perceived as a constant demonic assault upon christian values. thus did the enforcement of a collective conscience shift from the temporary and extraordinary to the permanent, universal and routine. handling these materials with quiet confidence, hill offers a thoughtful albeit slow-moving contribution to the debate both on heresy and on the bureaucratisation of late medieval power. not everything here is perfect. liber extra (p. ) was most definitely not ‘the next volume of canon law after gratian’. the decision to accompany every single word of latin with an english equivalent renders this an even slower read, where latin might have been most conveniently supplied in footnotes. nor are the translations (or the latin texts) invariably accurate. for a particularly egregious example, see text and translation at page , where inquisitor and constitutes should both be ablative, religiosi have become ‘friars’, questiones ‘torture’ and quinque ‘fifteen’. english exceptionalism perhaps explains the unwillingness to incorporate the debate on wycliffe or the lollards within the wider european discussion of heresy, creating an artificial and regrettable segregation in which english and european experts remain mutually deaf to one another’s attempts at analysis. as an introduction to two of the foundational texts of inquisition, nonetheless, this serves as both a perceptive and an intelligent guide. university of east anglia nicholas vincent early modern the norwich chamberlains’ accounts – to – . edited by carole rawcliffe. norfolk record society. . xii + pp. £ . /£ . . the chamberlains’ accounts of any early modern town or city serve the historian much as a thorough annual blood test serves the physician: each offers a succinct but deeply probing snapshot of nearly all bodily functions, whether that body be civic or human, at a particular point in time. yet the editing and transcription involved in producing such accounts for a modern readership is much more arduous, painstaking and downright ‘fiddly’ than the computer printout generated from the medical laboratory. as the raw but enormously detailed record of england’s second largest city, the financial accounts of norwich’s chamberlains between the years – and – have a lot to tell us about that particular body and provincial urban governance and society in general. carole rawcliffe has listened and transcribed with exemplary and patient care and edited her text with consummate clarity and judgement. what these accounts tell us, in minute detail, is that the health of norwich in these years was more parlous than uniformly robust, the product of wider contextual realities of the day as well as the past infirmities of the city itself. but they also tell us, in equally minute detail, how the city strove creatively and energetically to deal with the issues before it. beginning with a prolonged slump in the international textile trade, and thus a serious drop in local levels of employment and consumer spending, norwich’s troubles of the s were compounded by myriad additional concerns. the two devastating fires of , still vivid in the memory of older inhabitants, placed a continuing burden on c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices the city’s housing stock. when population growth made that loss of building fabric critically problematic, the city’s leadership had its mps enter a bill in parliament requesting relief. the response came in the statute enumerated as henry viii, c. , ‘an acte for the reedifying of voyde groundes in the citie of norwich’, which granted the civic authorities the authority to require landlords to repair decayed housing or face fines or forfeiture for failing to do so. that augmentation of civic control over the local building stock came just on the eve of the dissolution of the monasteries, which brought properties like the huge and lucrative blackfriars complex to the city by the end of that decade. along with the large addition to the east end of the guildhall, and supported by the robust contributions of several wealthy townsmen, these events spurred the local construction industry to new levels of activity and expenditure. the brick-by- brick details are among the most copiously recorded expenditures of the ensuing years. when the devastating plague of / , followed by severe dearth, brought myriad poverty-stricken survivors to the city in search of relief, that burden accrued to the food supply as well. along with the assistance of several individual wealthy benefactors, the city itself took extraordinary steps to manage the profusion of beggars and to regulate the food supply. when these same years brought sharply increased taxation to support henry viii’s military campaigns, the debasement of coinage and the fallout from the last monastic dissolutions, the city’s authorities cut back expenses wherever they could. they cancelled the traditional but expensive annual guild pageant in , cut back on the annual dredging of the river wensum, and dragged their heels on paving and cleaning of the streets. overall, these accounts offer a first-hand primer in the intricacies of civic governance at a time of rapid and unsettling change. they are particularly insightful on matters of civic finance, building and maintenance, and the economic, political and social issues of the day. in addition to rawcliffe’s scrupulous editing and transcription of the six annual accounts between / and / and her scholarly introduction to the whole, the volume offers four colour plates, a general glossary, a list of important local dates and days, and three appendices to support the text: an indenture describing the chamberlain’s duties, one chamberlain’s expenses during kett’s rebellion of , and an inventory of the city’s moveable goods in . as a measure of the health of england’s second largest city of the day, the volume as a whole provides an essential primer for understanding early modern english civic governance outside the familiar – but also unique – london metropolis. concordia university, montreal robert tittler dynastic politics and the british reformations, – . by michael questier. oxford university press. . xviii + pp. £ . . the central conundrum of post-reformation politics, this important work argues, was how to square the traditional dynastic strategies of early modern monarchs with the hardening religious positions of their subjects. michael questier revisits the great controversies of late sixteenth- and early seventeenth- c© the author(s). history c© the historical association and john wiley & sons ltd early modern century dynastic politics: elizabeth i’s marriage; the status of mary, queen of scots; the english succession, before and after mary’s execution; the matching of james vi and i’s children; and the bohemian revolt that sparked the thirty years war. he takes seriously contemporaries’ awareness about their possible implications for britain’s religious orientation: contingency is his watchword. professor questier emphasises catholic perspectives: crucially, the hope that dynastic union with catholic royal families would lead to toleration, maybe even to the restoration of the true church. this possibility ensured that catholic expectations outlived mary, queen of scots. questier’s book also explains why britain’s protestant monarchs valued (up to a point) their catholic subjects. relative lenity or harshness towards recusants sent signals to foreign powers (sometimes to raise their offers, sometimes to offset other unfulfilled commitments) and also defused domestic criticism (a feint one way to counterbalance a concession the other). for james vi, scotland’s catholic constituency offered leverage: it prevented him from being dependent on the elizabethan regime and encouraged other powers to imagine that, deep down, james was more sympathetic to the old religion than he could let on and thus might accede to the english throne unchallenged. with some chutzpah, british and irish catholics maintained that, unlike ‘the godly’, their loyalty was not conditional on the monarch’s religion. this position resonated because, for many committed protestants, the crown had indeed become instrumentalised as the agent of godliness, not only at home but also abroad. thus, the work concludes, charles i’s personal rule was rooted in what was in large part a catholic-inspired reading of forward protestantism as dangerously popular and antimonarchical. dynastic politics and the british reformations is an impressive volume: through an astute and intricate account of events and their contemporary interpretations, it powerfully vindicates the vital historical principle that ‘the future was not certain’. the author is being self-deprecating when he states that his book mostly retells other people’s scholarship. linking together such a detailed story requires a great command of a convoluted period. this mastery enables questier to demonstrate the interconnections between the british kingdoms, as separate states and then as part of a composite monarchy. he also shows how closely britons tracked the affairs of other european states, where they saw resemblances and lessons for their own polity. for instance, people remembered that the st bartholomew’s day massacre had been provoked by a cross-confessional mésalliance of the kind that james vi and i was now proposing. this is avowedly a ‘political narrative’ of the period: although his introduction mentions socio-cultural approaches to catholicism, questier does not draw on such scholarship thereafter and avoids the concept itself. the work’s underlying note is cynicism. gripping like a thriller, the narrative recounts disasters, pratfalls and embarrassments; hubris is reliably followed by nemesis. a sense of pervasive duplicity well accords with some contemporary perspectives. it will not surprise that ambassadors’ reports – the last word in speculation – are prominent sources, or that politic kinds of reading loom large. this approach may raise a paradox. such double-dealing occurred because questier’s cast (at least, most of them, we can only assume) really did care about religion: it was not a cloak for politics – if anything, the reverse. of course, this point is implicit in everything that the book addresses; it needs to be remembered lest, to coin a c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices phrase, this rather sardonic work be misread as history with the religion left out. university of cambridge paul cavill a protestant lord in james vi’s scotland: george keith, fifth earl marischal ( – ). by miles kerr-peterson. boydell. . xvi + pp. £ . . george keith, fifth earl marischal, has long been renowned for his wealth, his protestantism and his foundation of marischal college, aberdeen. miles kerr- peterson re-evaluates that reputation and, through examining some key aspects of marischal’s lordship, significantly modifies what we thought we knew about the man. in doing so, he makes an important contribution to how the scottish nobility during the reign of james vi is understood, building on the foundations laid down by jenny wormald and keith brown over recent decades. the book merits attention not because it is ground-breaking but because it ‘add[s] greater definition and detail to the picture’ (p. ). yet marischal seems an odd choice for such a study, given that the family’s papers were scattered and largely lost after forfeiture for choosing the wrong side in the jacobite rising. the first three chapters are the most detailed and sure-footed part of the book, given the breadth of the source-base for high politics and court intrigue. they chart marischal’s upbringing, and his involvement in government, politics and noble feuds. as a young man, he cultivated influence at court, involving himself in the factionalism of the s and early s, and his career as a courtier peaked in leading the embassy to denmark in – , standing as proxy for james vi in his marriage to princess anna. after , however, he withdrew from court and rarely attended the privy council. he did, however, make a brief return between and , perhaps due to unease at the prospect of the king’s quest for closer anglo-scottish union, which is also suggested by his refusal in to serve on the union commission. the latter half of the book approaches the last quarter-century of marischal’s life thematically. it is here that the loss of the family’s papers is most keenly felt, with frequent acknowledgement of the fact that there is much we cannot recover with regard to how he conducted his own affairs. there are tantalising glimpses of his management and development of his estates, and his exercise of ecclesiastical patronage, but the evidence does not allow a clear picture of his inclinations, goals and motivations to emerge. we do see that he invested heavily in developing peterhead and stonehaven. although barred from international trade because they were not royal burghs, peterhead provided an ideal setting- off point and first landfall for shipping to and from the baltic and scandinavia, and both ports lay between aberdeen and the next coastal royal burgh, so were able to act as safe-havens and staging posts. they were also well placed to profit from coastal trade and serve as outlets for the produce of the earl’s estates: a rare surviving account reveals a profit of £ , scots (£ , sterling) on shipments of his grain between and alone. marischal’s commitment to protestantism is traditionally seen in his upbringing, his rivalry with the catholic earl of huntly, and his foundation of marischal college as a rival to the conservative king’s college in old aberdeen. c© the authors. history published by the historical association and john wiley & sons ltd early modern yet he was no champion of the faith: kerr-peterson astutely points out that presbyterian writers like james melville and david calderwood, always eager to find noble champions, barely give him a mention. religion played only a minor role in his rivalry with huntly, nor did it stand in the way of his marriage to margaret home or cooperation with his catholic cousin, the earl of errol. as for king’s college, it was purged of catholicism long before marischal college was founded. the initiative was really a reaction to the laird of philorth’s attempts to found a college and royal burgh at fraserburgh. aberdeen did not want another royal burgh that close, so joined marischal to thwart the mutual threat. yet kerr- peterson also suggests that, in founding ‘a collegiate church for a protestant age’ (p. ), marischal was following a much older pattern. its staff never said masses for his soul but it guaranteed his reputation for centuries. marischal is thus reframed as a traditional nobleman, which explains his behaviour towards the churches under his patronage: he favoured kinsmen in parochial appointments and sought to appropriate benefices to support his children’s education. it is pithily observed that, in their dealings with the reformed church, ‘the earls marischal were protestant nobles, not noble protestants’ (p. ). we also learn that he rarely engaged in violence, preferring dispute resolution through litigation and negotiation, although he found himself on the receiving end of threats and overt use of force, even from his own family, which was not a happy one. his first marriage, to margaret home, nearly ended in divorce and the second followed less than a year after her death in to margaret ogilvie, who was no more than when they married (he was ). their first child, james, rebelled against his father in , in league with his mother’s lover. they raided marischal’s house of fetteresso, stripping it of its contents. in george died a rich man, but he was not surrounded by a loving family. his estranged wife did not attend the funeral and married her lover the following year. the book’s central message is that george keith’s career exhibits continuity rather than a shift in the role of the nobility in this period, reminding us that there was more to being an effective nobleman than political prominence. marischal’s energies were directed towards the maintenance, consolidation and aggrandisement of his estates, the enhancement of his regional power and the securing of his legacy. his overriding motivation was to cement the family’s hold on its estates through exploiting legal rights, careful management of resources, and investment with an eye to the long term. that he left the earldom in such robust health means that his career can be judged a success. university of dundee alan r. macdonald priest of nature: the religious worlds of isaac newton. by rob iliffe. oxford university press. . xii + pp. £ . . priest of nature presents a thorough, original and convincing analysis of newton’s religious thought up to the late seventeenth century. this book is largely based on rob iliffe’s three-decade research on newton’s manuscripts, now available online thanks to the newton project edited by iliffe. the book also draws on archival materials concerning newton’s early years, his scholarly activities at cambridge and his involvement in academic politics. furthermore, c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices iliffe’s attention to manuscript sources is matched by his solid knowledge of newton’s public writings together with the theories and authors that influenced newton’s context and intellectual growth. the first two chapters concentrate on newton’s family background, childhood and youth. examining newton’s years as a student at trinity college in the mid-seventeenth century, iliffe provides an enlightening description of life at cambridge in a period of profound religious and political crisis for the university. he pays attention to the impact that various events and people, such as cambridge scholars benjamin pulleyn and isaac barrow, had on newton’s education, piety and character. newton’s complex and problematic personality is a recurrent theme in this intellectual biography. this book, however, is not a traditional biography, in that the remaining ten chapters cover newton’s life up to the s by discretely analysing different elements of his religious thinking. the key topics addressed in this book include the relationship between newton’s scientific and religious ideas, his researches on early christianity, his anti-trinitarianism, his consideration of pre-christian religions and his apocalyptic studies. iliffe highlights the interconnections between newton’s scientific and hermeneutical methods, making a parallel between newton’s abhorrence of ‘imagination’ in religious thinking and his rejection of ‘hypotheses’ in scientific investigation: ‘the triumph of the imagination drew the godly man away from righteousness, just as the introduction of hypotheses into natural philosophy corrupted the pursuit of truth. the use of a proper method would terminate premature and uncorroborated speculation and produce undeniable philosophical truths’ (p. ). according to newton, the meticulous study of both scripture and the ‘book of nature’ inspired authentic piety and facilitated the search for truth. newton’s biblicism also informed his consideration of early christianity in his private writings, which show his anti-catholicism and anti-trinitarianism. newton concurred with other heterodox protestant intellectuals, such as his friend john locke, that catholic hierarchies, dogmas and traditions, as well as trinitarian doctrine, resulted from the degeneration of early christianity. according to newton, ‘the great athanasian conspiracy’ (p. ) played a primary role in the distortion of christianity and promoted the corruption of scripture with trinitarian interpolations like the johannine comma ( john : - ) and timothy : – two passages to which he devoted ‘an historical account of two notable corruptions in scripture’. iliffe provides a detailed analysis of newton’s manuscripts concerning athanasius and other ‘villains’ – mainly athanasius’s fellow-trinitarians and the monks who, according to newton, intentionally modified the biblical text. newton did not limit himself to denouncing the process of perversion of the christian religion since at least the council of nicaea. he formulated an anti-trinitarian, essentially arian christology, which, as iliffe observes, was indebted not only to his deep and extensive knowledge of scripture and early christian sources, but also to modern arian, socinian and unitarian texts. newton’s christian primitivism was also influenced by his conviction of the existence of prisca sapientia among ancient cultures. like various other seventeenth-century writers, such as gerard vossius, samuel bochart, and deists like herbert of cherbury and charles blount, to name but a few, newton thought that several ancient religious and philosophical systems presented c© the author(s). history c© the historical association and john wiley & sons ltd early modern notions consonant with proper morality and true piety. he valued the noachian law, egyptian wisdom, orphic and pythagorean philosophies, ancient atomism, the religion of stonehenge and biblical judaism, all of which, however, had deteriorated into idolatry and superstition. newton developed a naturalistic history of the corruption of ancient religions, which was caused by ‘the perverted adoration of heavenly bodies’ eventually leading to ‘the worship of dead men and statues’ (p. ). while arguing that priestcraft had a role in the growth and spread of idolatry, he claimed that ‘this was aided by the inveterately superstitious character of human beings’ (p. ). concerning ancient wisdom, iliffe has correctly noted that, despite the sincerity of newton’s christianity, his writings on prisca theologia, which describe christ as simply the restorer of the noachian religion, ‘implied that nothing much more was required of the true religion than to recognise the divine origins of the cosmos, to believe that christ was the messiah who was resurrected on the third day after his death, and to observe the moral obligations of christianity’ (p. ). thus, although in other writings newton attributed more prerogatives to christ, ‘the general thrust of his writings on the ancient religion is of a piece with his tendency to downgrade the role of the son in respect to that of the father’ (p. ). the internal coherence of newton’s religious thought is further demonstrated by his reflections on biblical prophecies and the apocalypse. in contextualising newton’s apocalyptic studies, iliffe calls attention to newton’s debt to other seventeenth-century authors – especially henry more and joseph mede – and thus shows that newton’s apocalyptic interests originated in religious concerns that were deep-rooted and widespread in seventeenth-century english culture. iliffe also highlights newton’s and other writers’ consideration of historical and contemporary events – from the early corruption of christianity to the conflicts and revolutions of the seventeenth century – as manifestations of a historical process predicted by scripture and heading towards the apocalypse. in this respect, iliffe’s analysis sheds new light on the reasons and factors behind newton’s involvement, as a representative of his university, in several political events – especially to oppose james ii’s interferences in academic life and, later, to support william and mary. moreover, newton was persuaded that ‘god had given his people prophesies so that they might be understood in the latter times’, particularly ‘at the end of time’, when ‘the wise, and not the wicked, would understand’ (p. ). newton’s scriptural references to the human understanding in his apocalyptic writings and his insistence on the constant study of scripture demonstrate his belief that ‘the perfection of the understanding involved the relentless study of sacred texts and the rational examination of the cosmos’ (p. ). the portrait of newton that emerges from this book is indeed that of a deeply religious man, who struggled with theological questions throughout his life. as iliffe points out in the concluding pages, newton’s life was actually ‘suffused with an overriding religious purpose. convinced that he had been created in the image of god, his scholarly life was in part an exercise in examining how he measured up to his maker. as such, it focussed both on perfecting himself and on understanding the works of god’ (p. ). in conclusion, iliffe’s extremely erudite, finely structured and intelligently written book offers an invaluable contribution to scholars and students willing to acquire a better understanding of newton’s life and work. it is hoped that iliffe c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices will continue his investigation of this subject and complement priest of nature with a second volume concerning newton’s last three decades, thus producing the defining work on newton’s religion for many years to come. american university in bulgaria diego lucci william penn: a life. by andrew r. murphy. oxford university press. . xiv + pp. $ . . andrew murphy paints a compelling portrait of william penn, proprietor of the english colony of pennsylvania from until his death in . a man of complex motivations and zealous prosecution of his affairs, penn was driven to protect his lands at all costs, to the detriment of his family and ultimately his own freedom and health. by the time he died, penn had saddled his widow and children with considerable debts, though provisions were made for them by the sale of his lands and the debts were eventually cleared through the good offices of his friends. his legacy to posterity, however, is far more precious. religious toleration, which he prized so highly, has left its residue upon the conscience of humanity. it was not always so. murphy begins his life of penn with him incarcerated in london’s fleet prison in , placed there after a public court battle with bridget ford, the widow of a former associate to whom penn owed a substantial sum. the sentence created a bleak outlook. for such a high-minded and principled figure, attempting to govern from across the ocean was both demoralising and expensive. a reprieve was given through the aid of friends. twenty years before, penn had made his way to america, with royal promises and charters in hand, to claim the colony for himself and begin the long and arduous process of surveying. ‘despite recruiting hundreds of investors into the enterprise and undertaking an impressive promotional and sales campaign,’ writes murphy, ‘he never realized the financial promise that american colonization dangled before his eyes’ (p. ). as an attempt to provide a full-length study, readers will find this a judicious and fair biography. without over-psychologising his subject, murphy portrays a young penn trying to earn the love of his father, admiral sir william penn of wiltshire, whose hopes for the boy’s future were never fulfilled. this was a problem exacerbated by the admiral’s absence due to his command or his later imprisonment by oliver cromwell in . the young penn began to have divine visitations shortly thereafter. at university, he did not get on well. by the time he was , penn had dropped out of oxford and renounced his affiliation with anglicanism. though he proved himself a worthy emissary to his father’s estates in ireland, young william’s prowess as a businessman was not enough to secure paternal sanction for his conversion, in , when he joined the society of friends. as a newly minted quaker, penn argued boldly for the right of religious toleration and grew in favour among the dissenters. by the age of he had printed the great case of liberty of conscience, which laid out the principles that would guide him for the rest of his life. murphy is especially adept at parsing the numerous and often complicated relations and negotiations penn made as the proprietor of pennsylvania. his c© the author(s). history c© the historical association and john wiley & sons ltd early modern protracted feud with lord baltimore over the lower counties (today, delaware), exchanges with members of the lords of trade and foreign plantations, secretaries and collectors who fell short of his expectations, pesky anglicans, and periodic flights from the law formed the crucible of his worries. though personally affable, penn was a firm and insistent proprietor: his correspondence with james logan, his secretary and agent in philadelphia, provides ample evidence of this. penn’s final illness saw his friends rally around him, but also saw him estranged from his eldest son. murphy keeps a respectable distance from assessing penn’s parenting, choosing instead to capture what can be gleaned from the sources, which suggest a warm and empathetic figure. however, murphy is not afraid of going into controversial areas, such as the awkward historical legacy brought about by penn’s ownership of at least five slaves. in all, this is a particularly welcome corrective, as penn has been poorly served by his biographers, who have veered between two extremes, portraying him as either a withering failure or someone who could nearly walk on water. redemptorist archives, philadelphia patrick j. hayes african kings and black slaves: sovereignty and dispossession in the early modern atlantic. by herman l. bennett. university of pennsylvania press. . pp. £ . . this is a slightly frustrating book. on the one hand it contributes significantly to our understanding of the very earliest years of european encounters with sub- saharan africans, but on the other it is sometimes not especially reader-friendly. bennett rightly contends that far too much of our understanding of european– african interactions is dominated by slavery and the slave trade. this dominant discourse of the seventeenth to the nineteenth centuries can easily be read backwards, shaping the analysis of the early encounters as well. bennett paints a different and entirely plausible picture. he notes that the portuguese merchants and explorers, who started to venture down the african coast from the s onwards, were acutely aware of the need to tread carefully. they were not conquistadors, instead they entered lands that had some powerful states exercising their own sovereignty. far from ignoring local power structures, the portuguese paid them all due deference, asking permission to go ashore, build settlements, and commence and then continue trade. bennett also contends that too much emphasis has been placed on various papal edicts that could be read as justifying european (i.e. christian) oppression of non-christian peoples. these, he points out, were largely intended to be used against islamic people in north africa and the middle east, where the ottomans were resurgent – taking constantinople in . although they would later be used against native americans, there is little evidence of these edicts being used against africans. the portuguese purchased slaves from the outset of their encounter with africans, but they were also aware that not all africans were potential slaves, only those who had already been designated as such by local rulers. by pointing out the medieval, rather than early modern, background of these encounters, bennett has certainly done a service to the academy. ideas about c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices power, sovereignty and law were different in the fifteenth century, compared to the later sixteenth or seventeenth centuries, and as such the interaction with africans was founded on a different basis. there is less engagement with ideas about race, and there has been some relevant writing on this topic (see the special issue of the william mary quarterly ‘constructing race’ january for instance) that could have been mentioned. also relevant, but overlooked, is the issue of disease. philip curtin has written about this extensively (but less so for the very early period), noting that whites were often forced to engage productively with local rulers because they were unable to sustain white settlements due to tropical diseases. i felt this was a missed opportunity. the frustrations i had with this book were due to structure and style. bennett spends a lot of time introducing the topic, justifying the need for this particular book, and analyses the historiography at length. while all this is perhaps necessary, i felt it went on too long and came at the expense of actual evidence. pretty much the first fifty pages are spent this way, one third of the book, and the historiographic discussions recur throughout. i did not find the style of writing very accessible. the sentences are complex, overly so, and my concern is that if this book was assigned to undergraduate students, they would need to sit there with a dictionary to hand to look up words. i confess i had to look up a couple myself. bennett also feels the need constantly to reframe and repeat points by using ‘asked differently’ or ‘stated differently’, which grates on the reader after a while. if the point could be made clearer there should not be a need to rephrase it all the time. given the variety of locations discussed, a map would have been helpful. bennett’s book is useful for academic specialists with a research interest in the early atlantic or the origins of the slave trade as i think he has made a genuine contribution to the field. sadly, i would find it hard to recommend it for classroom use. university of warwick tim lockley modern revisiting the polite and commercial people: essays in georgian politics, society, and culture in honour of paul langford. edited by elaine chalus and perry gauci. oxford university press. . xvii + pp. £ . . written by his students and close colleagues, this collection of essays celebrates paul langford’s hugely influential survey of english society and politics in the eighteenth century, a polite and commercial people: england – ( ). repudiating the view that this was an age of social and political stasis, langford’s book explored the ways in which the growth of commerce and trade, in tandem with the expansion of empire, ruptured the remnants of feudal society. in a bold move, he put the emergent middle class centre stage, arguing that it was their economic, cultural and political dynamism that transformed the country. a code of morals and manners, entwined with standards of taste and style, politeness was a way of fostering gentility among this dynamic group and generally civilising c© the author(s). history c© the historical association and john wiley & sons ltd modern them, so they could be integrated on some level into the class of gentlemen, and thus kept on side with the ‘plutocratic’ regime. under the headings of ‘politics’, ‘society and culture’ and ‘england, britain and the world’, these essays all engage with the core themes of langford’s work. but, as the editors observe, they also present an excellent opportunity to ponder ‘how the field has moved on since ’, at least as regards the study of political life. while none of the essays substantially challenge the ‘polite and commercial’ paradigm (in the manner, say, of e. p. thompson), there is much to be pleased about, all told. for whereas langford’s book was justly celebrated for broadening the canvas of political history beyond the confines of party and faction, the essays in this volume stretch it further still, encompassing a wider spectrum of the social and cultural forces shaping political life. a sample of the offerings will suffice to illustrate. examining the complex entanglements between high and low politics, as well as the increasing intertwinement of both with the world of commerce, the essays in section one set the tone nicely. accommodating competing interests was the order of the day for the political broker john paterson, according to perry gauci’s piece, as he advanced a programme of social regeneration for london. the secret of his success was his ability to mediate between the polite and the commercial worlds of london as represented by westminster and the city respectively, and to win support for his projects at a national level. with his elaborate web of influence, paterson typified the middle-class movers and shakers who drove historical change, according to langford. but ‘his exclusion from the highest political circles’ reminds us of the glass ceiling that still remained in national politics for non-aristocrats. shifting the focus to the nineteenth century, cindy mccreery’s essay traces the construction and reconstruction of william iv’s public persona in visual representations over the course of his reign. championing the contextual study of such images, she charts the remarkable shift in public attitude ‘from admiration to scorn and anger, and finally nostalgia, across a wide range of printed material’. in section two, hannah barker expands the field of vision to include the humbler echelons of the middle class, traders. drawing extensively on personal diaries, she argues convincingly that it was piety rather than gentility that the tradesmen and women of manchester strove to cultivate. if this was true of the lower middle classes generally, it would represent an important amendment to langford’s portrayal. section three widens the purview geographically to examine england’s global connections in the polite and commercial age. in the most ambitious essay of the volume, andrew jackson o’shaughnessy insists that british imperial policy towards america needs to be understood in the ‘the broader imperial context’. whereas the policies that culminated in the american revolution have previously been viewed as ad hoc reactions to problems of administration, when viewed in this broader light it becomes clear that they represented a newly developing attitude towards the empire, involving increasing centralisation. p. j. marshall follows the fortunes of the west indian planter and wheeler-dealer sir william young as he tried and ultimately failed to raise sufficient funds to cut a figure in polite british circles. the vignette of a family of slave owners who are celebrated for their humanity, even, it seems, by the slaves themselves, is deeply discomfiting. c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices with our stocktaking in mind, it is helpful to identify some of the roads apparently not taken. as one critic observed, there was less ‘straight political content’ in langford’s volume than there had been in its predecessor in the ‘oxford history of england’ series, basil williams’s the whig supremacy. there is less still in this volume. undoubtedly, the giant strides that have been made in broadening our conception of eighteenth-century political life are a cause for celebration. but it is vital that we follow langford’s example of interweaving the analysis of the broad political culture and lower-level structures of governance with the history of politics as conducted by crown and parliament, not least because it is on this level that the vast majority of people continue to engage with national affairs. it is evident, furthermore, that the field would benefit from a closer dialogue between social and intellectual historians. it is no accident that langford borrowed the title of his book from the great legal scholar william blackstone, or that he refers to no less than nine leading thinkers in his seven-page introduction. for not only were the men and women of letters the most perspicacious analysists of social developments in their age, but they were also instrumental in shaping the culture of the educated classes, not least by defining the terms of the discussion about what it meant to be living in a polite and commercial age. such voices are conspicuously quiet in this volume. for their part, intellectual historians, and particularly historians of political thought, need to come to grips with the more expansive understanding of political life that social historians have revealed. there is another important way, however, in which this volume enriches scholarship, and that is as a contribution to historiography. by carefully situating langford’s work in its intellectual context, chalus and gauci’s crisply written introduction succeeds in pinning down its significance for new generations of students. joanna innes’s meticulous precis of polite and commercial’s less famous twin public life and the propertied englishman – ( ) may help to rescue what, as she persuasively argues, was langford’s most original contribution to historical research from scholarly oblivion. she sifts coherent arguments from the circuitous thematic chapters and even translates them into a chronological narrative. what emerges is a sophisticated and penetrating account of how propertied society reshaped the political culture in response to the challenges of radical social and economic change. revisiting the polite and commercial people is beautifully presented. in their thematic diversity, the essays are a fitting tribute to a scholar so dedicated to broadening our approach to hanoverian politics and a testament to the rude health of eighteenth-century studies. king’s college london niall o’flaherty converting britannia: evangelicals and british public life, – . by gareth atkins. boydell. . xiv + pp. £ . . converting britannia: evangelicals and british public life, – is the first monograph from an already prolific writer on religion in eighteenth- and nineteenth-century britain. it is less concerned with the theological and intellectual issues atkins has tackled elsewhere, than with the question of c© the author(s). history c© the historical association and john wiley & sons ltd modern how a particular body of co-religionists managed to achieve disproportionate influence within the british establishment: or, in the author’s words, with how ‘evangelicalism . . . operated at the political and cultural “centre”’ (p. ). the book intervenes primarily in debates about evangelicalism, asking us to rethink the nature and chronology of the phenomenon. it also makes a series of arguments about the longer-term impacts of the evangelicals’ temporary institutional influence, connecting it with the fragmentation of religious authority in public life during the mid-nineteenth century, and with the dissemination of powerful discourses about the character of the british nation. the book’s main point is that the evangelicals were neither a tightly defined sect, nor (just) skilled marshals of political pressure from without. they need to be understood additionally, atkins argues, as a sprawling network of (mostly) men, concerned with the pursuit of hard institutional power, and relatively successful in securing it. evangelicals spread their tendrils through numerous repositories of public authority at home, and were similarly preoccupied with projecting their influence into the wider world. the two parts of the book fall on either side of this divide. chapters – deal respectively with the training and expansion of the evangelical clergy; with evangelical penetration of the city of london, business and bible societies; and with the place of the evangelicals as a party within the church of england. chapters – look in turn at the foundation of the free labour colony of sierra leone, and evangelical influence elsewhere in the colonial empire; at evangelicalism and the navy; and finally at evangelicals in the east india company. the book is completed by a notably elegant conclusion, which illuminatingly reflects on the volume’s implications for victorian history. converting britannia backs up its main claims far beyond the point of reasonable doubt. the scholarly labour behind the volume is imposing: visiting thirty separate archives is some undertaking, especially when much of the book is based on an even more intrepid mustering of very various printed sources. what it must have cost to compile the prosopographical database of , evangelical clergymen which underpins chapter hardly bears thinking about. throughout the book, evidence of all kinds is piled up hand over fist, until the reader is carried away by the tide. sometimes the lists – mainly of personal names, most of which only appear once (with dates), but also of parishes, societies, publications, subscriptions, appointments, etc. – border on the overwhelming. but a book about a large network and its societal reach must necessarily present a lot of data. in the light of atkins’s research, it will be impossible for future scholars to treat the close-knit ‘clapham sect’ as identical with political evangelicalism. the writing is uniformly precise, and readers who are not religious historians will find the book easy to follow, once they manage to recall the meanings of a few pieces of more recondite terminology dropped into the introduction. there are a few questions we might ask about the bigger picture. focusing on areas in which evangelicals were relatively successful means that the full scope of their ambitions, and the reasons behind their failures, become slightly obscured. did evangelicals seek power in other important arenas of public life (e.g. the judiciary, the army)? if not, why not, and if yes, why were they rebuffed? we might also wonder about just how self-conscious the evangelical assault on ‘the institutional high ground’ (p. ) was. atkins demonstrates that certain major figures who exercised moral leadership, like william wilberforce, or who commanded significant stores of patronage, like sir charles middleton at the c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices navy board, possessed a definite sense of duty to promote evangelical interests in public life. it is not quite so clear how far the co-religionist rank-and-file they manoeuvred into place shared the same goal of a specifically evangelical nation and empire. there is at least room to wonder about the levels of sympathy between the generals and the foot soldiers, even if this is a problem which is probably impossible to solve given the available sources. finally, on a similar note, atkins’s suggestion that evangelicals ‘were some of the best exponents of the languages and methods’ of the early nineteenth-century ‘“age of reform”’ (p. ) is also difficult to credit completely. this is simply because the book does not dwell on rhetoric or argumentation to the degree that would be necessary to draw persuasive conclusions about evangelical languages. the point may well be right, and it would be interesting to see further work around this issue. converting britannia vindicates its central theses with complete conviction, and presents a vision of how evangelicalism operated which must be taken into account in all future work on the subject. probably the book’s most important conceptual innovation, however, is that it draws attention to dynamic connections between spheres of late hanoverian public life which had previously been studied mainly in isolation: not just between the domestic political and imperial worlds, but also between seemingly distinct constituent elements of each. that it wraps all this up in a rigorous religious prosopography will make the volume a useful work of reference, as well as a significant revisionist analysis. it will be fascinating to see what students of both the eighteenth and nineteenth centuries ultimately do with atkins’s insights. christ church, university of oxford alex middleton the game of love in georgian england: courtship, emotions, and material culture. by sally holloway. oxford university press. . xiii + pp. £ . . according to sally holloway, ‘love, understood as a verb, is something that we do’ (p. ). in this book, holloway marshals an impressive array of evidence, including love letters, novels, medical treatises, lawsuits and material objects (from gloves to watch-papers), to investigate how courting couples in georgian england understood and practised romantic love. holloway first examines the language used in love letters, influenced by religious texts, medical theories and novels, and the role of the love letter in creating and furthering a romantic relationship. the second section turns to objects: the importance of a ritual and sensory interaction with objects for sustaining attachment, and the growing commercialisation of romantic objects by the late eighteenth century. finally, holloway turns to the romantic suffering expressed in letters, objects and breach of promise suits, arguing primarily that suffering in love was figured as a feminine experience. her emphasis on courtship and separation as emotional processes which were significant stages in their own right is a welcome addition to a historiography which has generally subsumed them within marriage. the book’s central argument is that the practice of romantic love changed between and , influenced by developments in medicine, philosophy, religion and consumer culture. c© the author(s). history c© the historical association and john wiley & sons ltd modern this book is primarily a history of emotions and material culture. holloway clearly explains the multiple and complex theoretical frameworks relevant to her analysis, making the book an accessible and useful introduction for students or readers new to these disciplines. the strength of the book is in its interdisciplinarity, as holloway seeks to analyse the practice of love from all angles and using multiple source types. one particularly effective and interesting theme is the embodied nature of love, understood through medical theories of love and heartbreak as well as through the sensory interaction of gazing at, touching and smelling objects exchanged in courtship. throughout, holloway excels at showing the relationship between culture and practice, providing detailed and precise evidence for the replication of cultural ‘scripts’ in individual relationships. holloway takes care to draw on a range of relationships, according to social status, gender and religion, although in the latter case it would have been interesting to include some non-protestant examples. gender was clearly significant to the experience and perception of romantic love, but holloway concludes that social status was less so: ‘in practice the language used by men and women across social classes was remarkably uniform’ (p. ). however, most of holloway’s examples are broadly middling, and perhaps more could have been done to uncover the experience of the poor. the book deals unevenly with socio- economic difference, and given the emphasis on material culture, i would have liked more on how the purchase and consumption of love objects was limited by economic status. nonetheless, the book is a fascinating addition to the histories of marriage and courtship, and a significant work within a growing scholarship on emotions and material culture. university of manchester kate gibson orphans of empire: the fate of london’s foundlings. by helen berry. oxford university press. . xv + pp. £ . . ‘the voices of orphaned and abandoned children are very difficult to hear: recovering them from almost years ago is almost but not quite impossible.’ so helen berry begins this brave and audacious book. in her acknowledgements, she is candid about her feelings in writing the book. ‘when i started my research on the london foundling hospital’s archive, i had no idea it would affect me so personally or engage my emotions so directly, and frankly i did not like it ... i didn’t anticipate i would find myself caring so passionately about the foundlings ... i was afraid i would not be able to complete the project.’ she could not disengage from the foundlings: ‘their voices kept crowding in, countless stories demanding to be told’. between the first baby’s arrival and , a total of , infants were carried through the gates in coram fields and received into the hospital’s care. this is the scale of berry’s project. she explains how they were quickly processed and sent on their way to different wet nurses, who were expected to care for them for their first year, across the home counties. what gives this book immense resonance is berry’s controlled objectivity in handling a huge subject which has many dimensions. we can empathise with the foundlings’ plight, she says. but what can we do with the story of foundling c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices hospital children, ‘to make sense of what happened to them and to think about the lasting issues which their experiences still address today?’ this british story was a different kind of one from the rescue of abandoned newborns elsewhere: in venice abandoned babies were left in a little boat down a discreet and narrow alley. in florence, where brunelleschi’s hospital of the innocents draws our eyes by its architectural magnificence even today, a basin for depositing babies was placed in an arcade beyond the orphanage walls. dublin’s foundling hospital placed a revolving basket at the gate. berry answers her own question, by simply telling the story of the first hundred years of thomas coram’s experiment, in the context of the general history of treatment of children in britain and the wider world from the georgian period until the present. so who was thomas coram? berry paints an engaging portrait of him, ‘a plain speaking and passionate advocate for social reform’. he did not seek popularity; in fact he was good at alienating people, because he dedicated his life, she asserts, ‘to being a good patriot’. she sees him as ‘wedded to the creation of a fiscal- military state’, which would expand the colonial empire. if coram wanted to save souls, he wanted quite as much to increase national prosperity. hence berry’s title orphans of empire. yet we learn that most of coram’s children did not in fact go abroad. helen berry nevertheless found a hero for her book in one orphan who did go abroad by joining the navy. he was george king. his story, from infancy to his death in , runs like a golden thread through this book. in fact, it redeems its whole tragic story of brutality towards and exploitation of orphan children, by bringing her account to a thrilling and unexpected climax. king was present at and wrote his own account of the battle of trafalgar in . he then ended up in retirement as a greenwich pensioner. she restrains herself from overplaying this hero waiting in the wings. she tells his story carefully: having left him as an apprentice in a london sweet shop many pages back, in a mere twenty-three pages at the end of the book comes the dénouement. what a magnificent story it is to be sure! it is the subtitle which really explains the content of much of berry’s book. moreover, there is much to celebrate in orphans of empire, besides its brilliantly conceived structure, its pace and its tantalising hero. for berry has anatomised this whole extraordinary georgian social experiment, peopled it with those who managed it across england and made sense of how coram, struggling at first, caught the social consciences of many, who did actually care for some of the children who were received at his hospital. coram showed superb organisation and commitment to his cause. ‘what mattered to coram’, berry notes, ‘was that aristocratic women were highly influential, well connected and of impeccable reputation, married to powerful and wealthy men with direct access to political power both at court and in parliament.’ she explains how he ‘took advantage of the new mechanisms that existed in the city of london to centralize fundraising’. petitioning george ii in , he was unequivocal about the project for which he had lobbied for so long: ‘using powerful rhetoric, he played upon the elite’s worst fears about the widespread moral and social degradation among the urban poor’. it was when he was , in , that the royal charter for the foundation of the hospital was finally granted. coram had sent the king a list of potential governors, about half of whom had agreed to be active not just honorary c© the author(s). history c© the historical association and john wiley & sons ltd modern signatories. this was, as he told a clergyman friend in boston, new england in , ‘my darling project’. foundlings were admitted in batches of twenty. a ballot, in the form of a bag containing white and black balls, was soon needed on each admission day. when a mother stepped forward, if she chose a white ball at random her child was admitted and she would not see her child again. at the poignant moment of separation, it was usual for mothers to leave tokens with the child – a key, a charm or a button – so they could identify their offspring again should they ever be in a position to reclaim them. from the late s, very movingly, it became customary for mothers to leave their clothes with the child. john styles has described how this explains the most significant surviving textile collection from the eighteenth century, documenting the everyday clothing of pauper women. the ‘billet book’ describes the clothing worn by the child on admission and it had samples attached; each child received a number and the foundlings were then placed in identical clothing to the others admitted that day. in chapter on ‘a fashionable cause’, berry gives attention to jonas hanway, a governor of the foundling hospital and a lobbyist who ‘did more than any single person to calculate the economic and human costs of poverty in the eighteenth century’. his ‘christian mercantilism’ was a popular ideology which advocated free trade. here were the underpinnings of the hospital’s raison d’être. in four central chapters of the book, berry discusses ‘foundling education’ and finding work for the hospital orphans. with sections on ‘industry and idleness’ and ‘cruelty and kindness’, the book becomes a hard read. we understand what, as its author, berry went through. her footnotes, by then, are dotted with foundlings’ individual numbers, ready for future researchers, who will have available the digitised entries soon to be created for the billet books. chapter brings release, when, under the title ‘outrageous fortune’, berry finally tells george king’s whole moving and arresting personal story. keeping this to the end, which anyway chronologically made sense, was permissible author’s privilege. this makes orphans of empire, masterly and relaxed, a triumph of storytelling. it is also, of course, a first-rate scholarly study. independent scholar anthony fletcher reform catholicism and the international suppression of the jesuits in enlightenment europe. by dale k. van kley. yale university press. . xii + pp. $ . . dale van kley made his scholarly name in with a brilliant analysis of the expulsion of the society of jesus from france in the s. he conclusively demonstrated that it was largely the work of jansenist magistrates rather than the anticlerical tirades of the philosophes. but the jesuits were not only expelled from france. between and they were also expelled from the iberian kingdoms and their overseas empires, and from the bourbon states of italy. finally in the entire society was dissolved by the pope himself. the destruction of these leading agents of the post-reformation catholic church was the most traumatic event in its history before the shocks of french revolution. after half a century of further research during which he established unrivalled c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices authority in the history of eighteenth century catholicism, van kley has now widened his purview to take in the whole international story of the dissolution. it is a formidable achievement, demanding wide linguistic skills, extensive archival explorations, and mastery of a vast range of doctrinal writings and secondary scholarship. of the argument’s three parts, the first seeks to define the concept of reform catholicism, and separate it from what has often been called enlightenment catholicism. indeed it is something of a surprise that van kley even allows the word ‘enlightenment’ into his title. certainly there were ways in which principles identifiable as ‘enlightened’ were taken on board by elements in the church, and by none more than the flexibly minded jesuits; but these were often among trends which reform catholicism sought to combat. the latter was more a blend of traditions in augustinian theology and anti-papal or ‘gallican’ principles of church organisation. it is true that its dominant elements were jansenist, and largely reflected french conflicts stemming from the bull unigenitus, but the term also embraces wider tendencies within the church and the growing ambitions of other catholic states. what drew it all together was hostility to the jesuits and all they stood for or symbolised. how this hostility played out is the subject of part , a dense analysis of the ecclesiastical politics of each anti-jesuit state, and their relationship with successive popes. one of the charges directed at the society was that it was a sort of conspiracy against secular monarchical power; but if there was a conspiracy in all this, it was directed against the jesuits. its epicentre was in rome itself, among members of the so-called archetto group around the indefatigable giovanni gaetano bottari, the vatican librarian no less, but a jansenist with contacts all over europe. its influence was hortatory rather than organisational, but it kept reformers everywhere apprised of developments in rome, and how they might be managed. even so, much depended at every stage on unmanageable contingencies. would the french jesuits ever have been so vulnerable without the bankruptcy of their caribbean trading house, which brought their case before the parlement of paris? would charles iii of spain have become so obsessive about the jesuits if he had not been looking for scapegoats for the terrifying riots of ? what if the vehemently pro-jesuit clement xiii had not died suddenly in , allowing the bourbon monarchs to promote the election of a more pliable successor? more might have been said, incidentally, on the quiescence of the most elevated of all the catholic monarchies, that of the habsburgs. after all, both joseph ii and his brother, soon to be reform catholic rulers, were actually in rome at the time of the conclave. even clement xiv, who decreed the dissolution, seems to have been appalled by what he knew he had to do. he delayed and prevaricated as long as he could, and when the deed was done, it was by a brief, rather than a bull, suggesting that it might not be irrevocable. his successor pius vi, although he promised on election not to restore the society, clearly dreamed that one day it might be possible. a sign of his true sentiment was the bull auctorem fidei of , in effect a new unigenitus, condemning all the main tenets of those who had been the jesuits’ enemies, after the french revolution had posed even more fundamental threats. a third part of van kley’s text examines this era of guilty regret after , and the emergence of an ‘ultramontanist international’ bent on refurbishing papal authority across the church. many former jesuits were involved, and by the early s popular support for the roman reaction had become widespread. it was of little avail to a pope destined to die in french captivity in , but the price c© the author(s). history c© the historical association and john wiley & sons ltd modern paid by napoleon for peace with his successor was to recognise a scale of roman authority that none of the kings who brought the jesuits’ downfall to fruition would have accepted. and this was the pontiff who, as soon as napoleon fell, finally restored the jesuits. in his view, the rot which culminated in the french revolution’s war against the church had begun with the capitulation of . van kley’s labours have traced the high politics of the jesuit suppression, in all the major states involved, in definitive detail. he is far less interested in events at ground level. the clashes in paraguay, which began the jesuits’ agony, are quickly skimmed over, as are the tribulations of all the fathers expelled from portuguese, spanish and neapolitan jurisdiction in the years before the final suppression. and although he outlines the sheer range and scale of jesuit establishments throughout the catholic world, he tells us nothing about how colleges and other properties were wound up or disposed of, or what most of the , former fathers did after their lives were turned upside down. he does not even mention the challenge to catholic elite education posed by the sudden removal of its most successful practitioners. it was doubtless no part of the author’s intention to open up yet another vast field such as this. but somebody ought to, if we are ever to get an idea of the full significance and ramifications of the high-level decisions so carefully and convincingly analysed here. university of bristol william doyle dark matter credit: the development of peer-to-peer lending and banking in france. by philip t. hoffman, gilles postel-vinay, jean-laurent rosenthal. princeton university press. . pp. £ . . dark matter credit deals with an important and interesting subject in an unnecessarily hyperbolic way. ‘until now’, its authors announce on page , ‘virtually no-one’ had noticed the scale of non-bank sources of credit in the eighteenth- and nineteenth-century french economy. ‘our discovery’, they continue, ‘not only overturns the standard argument about banks and economic growth’, but also raises questions about the mechanisms involved in the allocation of credit before the rise of the banks. quite apart from the fact that the authors of this monograph have been publishing books and articles on the subject for the best part of two decades, it is hard to reconcile their claim that until now ‘virtually no-one’ noticed the scale and scope of non-bank credit, either with the many, often acute, observations on the relationship between credit, capital, and economic growth in france made, among others, by montesquieu in the eighteenth century, or with the equally widespread claims about the significance of non-bank sources of credit and capital in more recent studies of both the french economy and the broader process of industrialisation. the ‘standard argument’ about the relationship between banks and economic growth in france turns out, on inspection, to be an admirable, but no longer authoritative, book published in by rondo cameron, while anyone wanting to find out, for example, how it was possible to claim that roman law and its civil code offshoots ‘are thought to hobble financial development’, particularly when so many nineteenth-century commentators on roman law said something like the opposite, will look in vain in the book’s bibliography for the ‘seminal’ article c© the authors. history published by the historical association and john wiley & sons ltd reviews and short notices referred to in the text as ‘lopez-de-silanes, shleifer, vishny ( )’ until they discover the name of the article’s fourth author (rafael la porta) under the letter p. the work of stanley chapman on the part played by attorneys in providing non-bank sources of credit in the early modern british economy is given much the same type of treatment as, more saliently, is the work of amalia kessler on the eighteenth-century paris merchant court and the range of commercial and credit-related disputes with which it dealt. that said, this book covers an impressive amount of ground, in both time and space. while it goes with the grain of many other more specialised studies of aspects of the french economy in the eighteenth and nineteenth centuries, from brandy production to the silk industry, printed textiles or merchant shipping, its broader aim, as its subtitle is intended to suggest, is to show how economic history can be used to reinforce the current interest in the relationship between economic growth and non-bank sources of credit. peer-to-peer lending, its authors claim, reached the parts of the french economy that banks were not yet able, or available, to do. here, the emphasis falls on notaries as analogous to banks, but with the further advantage that notaries were locally decentralised, sometimes worked with other notaries and, most importantly, had access to information that could facilitate both the supply and demand side of credit relationships. in france, from , the deeds that notaries drew up and kept were subject to a royal tax called the contrôle des actes, a duty levied on notarised transactions that was collected by an extensive network of administrative officials whose records still largely survive. the content of this book is based on a sample of some , of these notarised transactions carried out in approximately localities over a series of six sample years spread between and . the result is an analytically sophisticated overview of the scale and scope of non-bank sources of credit set out as a sequence of images of the many, more or less extensive, networks of information and credit that accompanied the growth and fluctuations of the french economy in the eighteenth and nineteenth centuries. king’s college, cambridge michael sonenscher imagining britain’s economic future, c. – : trade, consumerism, and global markets. edited by david thackeray, andrew thompson and richard toye. palgrave macmillan. . xv + pp. £ . . no topic is seemingly so ripe for historical analysis than the study of past visions of britain’s economic future, and this volume offers a rich variety of insights into this theme from the first ‘opium war’ to entry to the common market. the book is divided into three sections ‘markets of the future’, ‘imagining global trade’, ‘rethinking decolonisation’, but the majority of chapters address the central theme of trade in the ‘british world’, especially the british dominions, in the century after . disappointingly, at a time when britain’s return to its mid-nineteenth-century ‘global’, supposedly buccaneering past is being widely touted, britain’s emergence as a global economic power is treated only in respect to the debate over the opium trade in the s, with no coverage of the wider early nineteenth-century debates over the future direction of the first industrial nation. even so, if political economy is missing, there is c© the author(s). history c© the historical association and john wiley & sons ltd modern a fascinating and original study by paul young of geographical board games, whose extent and popularity in itself illustrates the burgeoning global sense of the british public. similarly when we are presented daily with a possible future based on an anglo-american trade axis, only one chapter touches on anglo-american relations, in which stephen tuffnell, in an elegant essay, complicates the picture of britain’s late nineteenth-century imperial project by dissecting the importance of american business within it in the case of south africa. marc-william palen engagingly but briefly takes up the theme of britain’s global free trade vision but confines his analysis to the extent to which this inspired internationalist feminist voices in the century after . the theme therefore which unites the greatest number of chapters is that of the rise and fall of the interwar emphasis on imperial trade, and the organised form this took after the ottawa economic conference of . this imperial trading system was in part the legacy of the greater britain projects of the late nineteenth century, but the ‘british world’ economic bloc was to fade in importance in the light of rising american economic power, sealed by the second world war, and it was finally eroded by the swing to europe in the s. two of the editors, thackeray and toye, besides their lucid introduction with thompson, combine to dissect the aspirations, rarely achieved, of those who sought to promote patriotic trade in these years. dilley, in a clearly focused chapter, analyses, through the example of the federation of commonwealth chambers of commerce, the waning of visions of commonwealth trade as europe by the s became the cynosure of those wishing to revive britain’s economic future. o’hara neatly illustrates the wider theme in showing the growing detachment of new zealand from earlier commonwealth dreams, while clayton reveals the divided visions of capitalism in hong kong before it became the great example of free market capitalism beloved by thatcherites such as sir keith joseph. finally, ludlow authoritatively explains why the commercial case for europe made compelling sense to business, most conservatives and the nation as a whole in the s as the public prioritised economic welfare and consumer choice over fading imperial dreams, residual commonwealth loyalties and labour ‘siege economy’ aspirations. these chapters cohere well together but others, on the rise of self-service shopping, capital investment in west africa and british overseas representation in francophone africa, whatever their inherent scholarly interest, seem somewhat out of place in a collection dealing primarily with the direction of britain’s overseas trade in goods. most of the chapters engage effectively with the themes of the book’s subtitle, ‘trade, consumerism, and global markets’, with pertinent material on the marketplace, business, the state, consumers and their associations, chambers of commerce and advertising, but, perhaps oddly, economists’ visions of the future rarely appear. given the topicality of the book’s theme, which has perhaps gained in importance during its genesis, this collection, however valuable for its parts, seems a missed opportunity for a tightly focused and comprehensive analysis of britain’s past economic futures, made all the more urgent by the reimagining of a previously ‘global britain’ as a foremost contemporary political dream. university of east anglia anthony howe c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices the second seminole war and the limits of american aggression. by c. s. monaco. johns hopkins university press. . xiv + pp. $ . . divided into four parts, c. s. monaco’s study of the second seminole war posits that this conflict provides a clear example of settler-colonialism. part focuses on explaining the origins of the war. part provides a lively narrative of the war’s progress and conclusion. part examines the effect of environmental forces on the war’s participants. finally, part speaks to the war’s influence on american political culture through the symbolism of osceola and the connection of abolitionism to contemporary discussion of the war effort. monaco clearly articulates his argument that the war ‘was the boldest and most enduring armed struggle by eastern indians against the forces of the united states’ (p. ). in contrast to previous studies of the war, his narrative is sympathetic to the seminole and their allies, in part because he does not simply take white american or american government sources at face value. monaco is at his strongest when narrating the development of the war. he provides fascinating details that are sure to engage readers, as they did me. for example, monaco describes winfield scott’s ‘personal hubris’, which ‘resembled the manner of a rather haughty european aristocrat’. ‘in addition to his own retinue, which included choice musicians outfitted in full regalia,’ monaco continues, ‘three wagons were required to transport the general’s personal collection of fine furniture and accoutrements, imported wines, fresh fruit, and myriad other comforts’ (p. ). not only do these details grab the reader’s attention, they also help explain why an arrogant united states army struggled to defeat an enemy it considered inferior. two authorial decisions make this book less effective than it might otherwise have been. first is monaco’s frequent reference in the main text to other historians and their arguments. this interruption of the narrative seems likely to limit the reach of the book, since most readers will, as i did, find it distracting. it probably would have been better to relegate the scholarly fisticuffs to the endnotes or to omit them entirely. second is the book’s organisation. on their own, parts and are fascinating and informative. but because they are separate from, and not interwoven with, the first two parts of the book, they feel disconnected from the main narrative. chapter , which introduces part and which focuses on disease, particularly suffers from this detachment. overall, monaco’s work is a valuable addition to the often-neglected study of the second seminole war. while overshadowed by the atrocities suffered by the cherokee on the trail of tears, the seminoles’ struggle to maintain their sovereignty in florida was important in several ways. as monaco points out, the war harmed an already weak economy, ‘delivered a severe setback to andrew jackson’s mission of indian removal, conjured visions of a pan-indian rebellion, and contradicted the deep-rooted national conviction that the military would forever triumph over native people’ (pp. , ). for these reasons, which monaco clearly spells out, i hope that historians of the jacksonian period begin to give the war the attention that it deserves. cumberland university mark r. cheathem c© the author(s). history c© the historical association and john wiley & sons ltd modern the russian nobility in the age of alexander i. by patrick o’meara. bloomsbury academic. . xvi + pp. £ . . russia boasts a rich tradition of history writing and a massive historiography (pre-revolutionary, soviet and post-soviet) which must be incorporated into any scholarly discussion of critical themes and questions. the relationship of emperor alexander i to the russian nobility is just such a topic. patrick o’meara has done a masterful job of synthesising the available scholarship, russian and foreign, while also presenting original research based on provincial and personal archives, memoirs and diaries, and private correspondence. in today’s world of seemingly infinite access to information, this is precisely the sort of book that seasoned scholars and advanced students need (and want) to read. indeed, for anyone beginning a project on the russian nobility or the age of alexander i, o’meara’s study is a productive place to start. the biography of alexander i looms large in the historiography of early nineteenth-century russia. but o’meara takes a different tack, and in the process, he suggests compelling answers to persistent questions, including questions about the character and intentions of the monarch. for example, what did alexander think about constitutional reform and the abolition of serfdom? did he really intend or hope to transform russia? how did his goals and policies change in the context of ongoing revolutionary activity and consolidation of the holy alliance in europe? o’meara illuminates these and other issues by examining the broader relationship between alexander i and the russian nobility, both the nobility writ large and the individual elite nobles who produced projects for reform and in some cases joined the secret societies that eventually organised the decembrist uprising. one general conclusion reached by o’meara is that a key reason for alexander’s failure to pursue fundamental reform, whether socio-economic or political, was opposition from the majority of nobles, who preferred to leave intact the tsar’s power over the empire and their own authority over the peasants. another significant theme explored in o’meara’s book concerns what historians call ‘the parting of ways’ between the elite nobility (or the educated service classes more broadly) and the russian state and monarchy. here o’meara draws upon his extensive experience in researching the decembrist rebellion, russia’s first modern political opposition which sought to overthrow established social and political arrangements. o’meara is fully aware of, and clearly conveys, the complexity of decembrist historiography, including recent debates about how to define the ‘decembrist phenomenon’ and who exactly should be called a decembrist. given that the subject of his book is alexander i’s relationship with the nobility, o’meara focuses attention on how the monarch’s ongoing interest in reform and avowal of ‘liberal’ principles contributed to disillusionment and radicalism among the military officers who eventually crossed the line from enlightened reformism to open insurrection. the decembrists failed to connect both with the soldiers under their command and with the mass of provincial nobles. they likewise proved unable to convince many educated russians who shared their progressive goals that revolutionary violence represented the only way forward. the decembrists’ isolation resulted in defeat and severe suppression, but their actions still produced a shift in the trajectory of the nobility’s relationship with the crown. as o’meara notes in the afterword, although most nobles continued to believe in the need for a single powerful ruler, the decembrist phenomenon severed the compact to reform russian institutions c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices which in the eighteenth century had defined the relationship between the elite nobility and the throne. in addition to addressing big questions that have persisted in russian historiography, o’meara also provides up-to-date information about a variety of topics that influenced the development of the nobility. these include legal and economic status(es), the development of education, service obligations and opportunities, attitudes to serfdom, and most originally the nobility’s corporate institutions and participation in provincial government. o’meara’s discussion of noble assemblies, judicial institutions and local administration is based primarily on archival documents from nizhnii novgorod province. in this material the reader again finds potential answers to difficult questions of interpretation, as well as illuminating facts about a seriously understudied subject. the author connects the nobles’ lack of interest in their corporate institutions and efforts to avoid service in local government to the larger problem of ineffective provincial administration. although there are pre-revolutionary studies (discussed by o’meara) that examine this very important dynamic, subjects such as the activities of noble assemblies and the nobility’s willingness to entrust local government to state officials remain in need of comprehensive scholarly treatment. o’meara’s discussion of how and why the russian nobility abdicated responsibility for local government is a topic that historians will continue to debate. did the mass of nobles in fact prefer autocratic rule? what role did serfdom and service play in their apparent desire to retreat into the consumption of culture and the routines of the family nest? put simply and unequivocally, o’meara’s book is a delight to read. for anglophone historians especially, it will be a go-to study of the russian nobility – not only for the reign of alexander i but also for the entire imperial period. california state polytechnic university elise kimerling wirtschafter demos assembled: democracy and the international origins of the modern state, – . by stephen w. sawyer. university of chicago press. . ix + pp. $ . . there are numerous books about the origins of the state from the early renaissance to the seventeenth century. there are also countless books about democracy, focusing on aspects such as its ancient form, democratic sovereignty and modern representative government, with the two latter categories concentrating in particular on the seventeenth and eighteenth centuries. what stephen w. sawyer investigates in this book is the genesis of a later and less understood phenomenon: the ‘democratic state’. his story focuses on mid-nineteenth-century france, with the emphasis on , the second french empire and the early years of the third republic. in this period, the understanding of the state was transformed from the minimalist night-watchman eighteenth-century ideal into its modern, activist character. [correction added on march , after first online publication: date of paris commune from “ ” to “ ”] c© the author(s). history c© the historical association and john wiley & sons ltd modern sawyer argues that french republicanism fostered a new interventionist state which influenced other political cultures usually considered as more laissez-faire, including nineteenth-century britain. this can be seen in the affinity between the liberal john stuart mill and the socialist louis blanc, which is discussed in the final chapter of the book. as the latter succinctly put it, ‘yes, the state and liberty!’ (p. ). by the time of the third republic in france, ‘jacobin’ radicals, mainstream republicans and liberals could all agree that the republic needed to be the final arbiter and had the right to employ emergency powers in situations of crisis. on this basis, blanc defended the thiers government’s violent suppression of the paris commune in . as we shall see below, even some of those who disagreed in that case were not against strong state power as such. demos assembled is structured as six chapters, each dealing with one french nineteenth-century thinker and a specific theme: alexis de tocqueville and inequality; lucien-anatole prévost-paradol and equality; edouard laboulaye and emergency; adolphe thiers and necessity; jenny d’héricourt and exclusion; and, finally, blanc and terror. this rather strict concentration on french thinkers makes the ‘international’ in the subtitle seem rather odd. to be sure, sawyer puts a great deal of emphasis on the influence of the british and american constitutional models on french political thinking. the energy of the american presidency in general and abraham lincoln in particular was attractive for many french thinkers in the nineteenth century. the french empire in algeria is a recurrent theme. and in the final chapter, sawyer discusses blanc in the context of british thinkers such as mill, thomas carlyle and a. v. dicey. yet, in any case, ‘french’ would probably have been more suitable in the subtitle than ‘international’. what brings many of the political writers in sawyer’s study together is the preoccupation with democracy beyond the vote, something for which tocqueville is of course especially well known. democracy had to be social in addition to political. the ‘democratic despotism’ of napoleon iii showed in practice that the vote could be a problem as well as a solution. one of the authors who wrote both during and after napoleon iii’s reign was the feminist d’héricourt, who argued that france needed to make use of all the tools for social improvement by including women in politics. at the same time, she challenged the ‘throne of suffrage’. in order for the vote to be meaningful, the state should play an active role and ‘provide the conditions for each to develop fully his or her individual capacities within society’ (p. ). as part of the process of equal participation, d’héricourt stressed the importance of adversarial debate, and distinguished carefully between adversaries, who could disagree and argue, and enemies, for whom force would be the mediator. deeply critical of napoleon iii’s illiberal democracy, she desired cultivation and expression of difference rather than unified popular will. d’héricourt was, like thiers and laboulaye, influenced by the american state, and she lived in chicago between and , where she was active in the feminist movement. in the united states, government respected rights and especially the right to debate, which ‘established an appropriate relationship between the government and the governed because it was constantly subject to public opinion’ (p. ). in this way, the freedom and ability to form opinions and debate was more important than voting. rather than being distinctive, civil society and the state permeated one another in the united states. d’héricourt also wanted french citizens to have the right to bear arms like their american c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices counterparts, as she had followed from a distance the bloody suppression of the paris commune. sawyer’s book is both historically and theoretically refined, and although it may make a slightly narrower contribution than its subtitle suggests (although by no means a narrow one as such), it will be important for anyone interested in the origins of the modern state and democracy. university of liverpool max skjönsberg lloyd george: statesman or scoundrel. by richard wilkinson. i. b. tauris. . xvii + pp. £ . . lloyd george has not been short of biographers and the stream of writings on his life shows little sign of drying up – this book is the second biography of lloyd george published by i. b. tauris in four years, following travis crosby’s, the unknown lloyd george ( ). these writers all face the same difficulty, though, of how to deal with the length and variety of lloyd george’s career: elected an mp in , he only left the commons in , having played a key role in british politics for at least thirty years, from the early s onwards. this book takes the route trodden by many predecessors, such as martin pugh’s lloyd george ( ) and chris wrigley’s lloyd george ( ), of attempting to summarise the achievements and significance of the ‘welsh wizard’ in a short, accessible form. where it differs, though, is in the attention it pays to analysing, and passing judgements on, lloyd george’s character. this is the most entertaining and successful part of the book; indeed, some sections (such as pp. – ) are extremely well written and perceptive on lloyd george’s many failings and unrivalled charm, and are enlivened by a sure-footed choice of anecdotes and quotations to illustrate the author’s points. wilkinson’s work may well be the best introduction yet for those seeking to gain an initial idea of what lloyd george was like as a person and the extraordinary spell his personality could cast. however, the book also has some serious shortcomings. it lacks any sustained use of primary sources and this makes it difficult for it to say anything about lloyd george’s career that is really new. moreover, while its grasp of the political background to lloyd george’s career is strong in some areas, for example in its sections on the prime minister’s quarrels with his generals in the first world war, it is noticeably shaky in others. the treatment of subjects as varied as free trade, women’s suffrage before , the irish conflict of – and the strategic background to the versailles conference in lacks a firm grasp of key issues and the extensive historiography on these matters. at points the book just summarises the views of other scholars, or is over-dependent on one source, as in the description of lloyd george’s trip to the usa in , taken from a. j. sylvester’s diary (pp. – ). wilkinson’s work also displays a rather uneven treatment of the different sections of lloyd george’s life, with little time devoted to events after . there are also some factual errors that could easily have been avoided. to give two examples: on page the judgment in the taff vale case of becomes the c© the author(s). history c© the historical association and john wiley & sons ltd modern ‘tory taff vale act’ and the memberships of the two rail unions, the nur (which did not exist until ) and aslef, are confused; and the ‘geddes axe’ of – is attributed to auckland geddes (misspelled as ‘aukland’), rather than his brother, eric geddes. the book would have benefited from much more rigorous proofreading throughout and it is surprising to see an academic publisher such as i. b. tauris allow a book to proceed to press with so many mistakes, including missing and unfinished endnotes, and some repeated material (for example the same clemenceau anecdote appears on pp. and ). the book also contains asides in which the author interpolates his own views on a variety of topics in a rather puzzling fashion, as at page on contemporary ireland. these errors rather undermine any claim the book might have to be a rigorous treatment of lloyd george’s career and achievements. university of lincoln ian packer the zinoviev letter: the conspiracy that never dies. by gill bennett. oxford university press. . xv + pp. £ . . gill bennett will be familiar to historians of modern british intelligence history and foreign policy. her career was spent at the foreign and commonwealth office (fco), mostly in the its historical section, which she led for ten years. since then she has written about british foreign policy and intelligence history. during her time as chief historian, the fco, under robin cook, adopted a more transparent approach towards public records as well as the activities of the intelligence services. in , cook invited the fco historians to investigate the circumstances surrounding the zinoviev letter. the letter, allegedly sent by the head of the comintern, grigori zinoviev, to the communist party of great britain, sought to incite insurrection. together with a note of protest, written in the foreign office, but not sanctioned by prime minister and foreign secretary ramsay macdonald, the letter was leaked to and published in the daily mail just prior to the october general election. as bennett suggests, the letter damaged support for labour but did not lose them the election (p. ). cook’s instruction led bennett, and tony bishop, a russian-speaking fco colleague, to various archives in moscow, where the authorities were cooperative. when writing her report, which was published in , she also had unfettered access to material held by britain’s intelligence agencies. that was not the case with this volume and bennett admits that, since the report’s publication, she has not substantively altered her conclusions about the genesis of the letter. however, the book is welcome because it distils a huge amount of research along with much mature reflection on the letter, the context in which it was written, and its periodic recurrence in british politics ever since. the book is a tour de force, forensic in style, and very well written. bennett is particularly good at contextualising discussion of the letter from the troubled aftermath of the first world war until recent times. concerning the letter’s conception, she does so with regard to post-war concerns about imperial security, oversight and perceptions of the intelligence agencies (as well as overlap between these agencies), and contacts between these bodies and white émigré russians. a key aspect of the story concerns the networks within and beyond c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices whitehall, some of whose members were receptive to circulating a document which might embarrass the labour government. bennett examines the long list of possible suspects, among them the foreign office’s sir eyre crowe. his slippery subaltern, ‘don’ gregory, is scrutinised more closely: the francs scandal, which ended his career, was intertwined with the letter. however, bennett’s painstaking study leads her to reject as ‘inherently unlikely’ (p. ) institutional conspiracy either at the foreign office or, though with less certainty, because of the ‘private enterprise’ of sis people in riga (p. ), within the intelligence services. one legacy of the letter was to tarnish those agencies’ reputations, particularly in the eyes of labour, and to raise fears within it of being hobbled by further intelligence leaks. this is an authoritative and judicious study of a conspiracy which, as bennett concludes, is dormant but not deceased. university of the west of england john fisher the prohibition era and policing: a legacy of misregulation. by wesley oliver. vanderbilt university press. . x + pp. £ . . prohibition has often been romanticised in us history as a ‘noble experiment’ designed to clamp down on crime, corruption and alcoholism. wesley oliver’s the prohibition era and policing questions this narrative with a fresh and insightful perspective focused on how american courts responded to the excessive policing that symbolised this period. oliver’s niche comes in his criticism of the growing invocation of the ‘exclusionary rule’ by judges, which prevented the use of evidence in courts when police officers were found to have cut constitutional corners in the search of property. this, he explains, prompted an obsessive focus on the legality of police searches to the extent that it became the subsequent default legal solution for addressing police misconduct. nearly years on, this legacy remains, which, oliver argues, has deflected attention away from today’s more pressing concerns, such as the reliability of evidence and police brutality. the book consists of nine chapters, divided into four sections. to contextualise his arguments, oliver’s first section traces the nature of policing in the early republic up to the prohibition era. with the deep-rooted scepticism of enforcement officials still pervading from revolutionary-era collective memory, he frames the conduct of police officers through their limitations rather than their powers. describing it as a ‘victim-initiated criminal justice system’ (p. ), he reveals how judges placed the burden upon the victim of a crime to provide the probable cause necessary to gain a search warrant against the person they were accusing. however, as rapid urbanisation followed, the public was convinced by progressive reformers that a professionalised force was necessary. thus, oliver reveals a rapid transformation from a ‘petty’ police force to an organisation emboldened, self-regulated and nearly unfettered in its powers. for historians intrigued with this era, part is where the book is most stimulating. the new image of a strong and intimidating police force quickly lost support after congress passed the eighteenth amendment to the us constitution to prohibit alcohol in the country. violent police methods suddenly c© the author(s). history c© the historical association and john wiley & sons ltd modern magnified in the public eye, as they now posed a more frequent and visible presence. oliver details examples of such methods using the findings of the wickersham commission, set up in . the commission investigated nearly every aspect of the criminal justice system, but the greatest attention was given to its ‘scathing report detailing incidents of physical torture by police interrogators’ (p. ). in one example, oliver describes how a suspect in washington dc was detained by police in a hotel room for eight days of interrogation despite being so ill with spanish influenza that a physician was frequently called to check on him (p. ). oliver convincingly argues that the discord between police and citizenry had become a nationwide problem, a view that is reinforced by his extensive research, which covers examples of police misconduct from coast to coast, spanning the states of washington to new york. oliver’s most striking argument is that the judicial responses to police misconduct proved the most destructive legacy of prohibition. judges throughout the country began excluding coerced confessions and illegally obtained evidence in an attempt to deter further misconduct. however, the exclusionary rule’s scope was limited by its strong focus on police searches. this left lingering effects when the nature of police issues grew in the decades that followed, but courts failed to adapt. in parts and , oliver reveals these effects, connecting his historical era of focus to the current day. long after prohibition, courts continued to adopt the exclusionary rule as the answer to all questions regarding police conduct. the most damaging consequence was further heavy regulation of police searches and seizures at the expense of addressing forced confessions. oliver’s best example is the famous supreme court case of miranda v. arizona, which set out the requirement of excluding incriminating evidence where law officers failed to advise suspects of their rights to remain silent and have access to an attorney. in essence, he argues that the court placed the burden on the suspects to protect themselves. it was their responsibility to have the agency and composure to ‘determine . . . whether they are willing to submit to police questioning while in custody’ (p. ). this, however, did not guarantee the reliability of the confession, nor regulate the means with which that confession was obtained once individuals unwittingly waived their rights. thus, oliver notes, as long as suspects’ rights were read out, there was ‘little protection’ from the coercive nature of the interrogation (ibid.). this legacy, the book argues, continues to plague policing practices in the united states today, where the court is still unable to present successful ways of tempering police misconduct. oliver gives particular attention to contemporary issues of police brutality and the recent contentious deaths of african-american males, such as michael brown and eric garner. under this pressing issue, the court continues to present vague instructions concerning the correct manner of force used by an officer, arguing separately that officers do not have a right to use lethal force on a fleeing suspect connected to a non-violent crime, but acknowledging that officers can and should use split-second decisions regarding the use of lethal or non-lethal force. those seeking information on the prohibition era will be surprised about how little there is on the period itself. nonetheless, the book presents an insightful link from past to present. even if prohibition is not the full focus, the consequences of this period leave their presence felt throughout the book and make it a must-read for those interested in how this period has shaped issues with which americans c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices continue to grapple. in turn, oliver leaves the reader with a suggestion for more critical introspection about how courts can reshape the conduct of those officers currently serving on the front line. university of kent jak allen macarthur’s spies: the soldier, the singer and the spymaster who defied the japanese in world war ii. by peter eisner. penguin. . xv + pp. $ . . justifying general macarthur’s refusal to cooperate with the office of strategic services (oss), general willoughby, his assistant chief of staff for intelligence, wrote that macarthur ‘had to improvise his intelligence from scratch with the japanese breathing down his neck. he could not sit back and ransack libraries, even assuming data were there’ (clayton d. laurie, ‘an exclusionary position: general macarthur and the oss, – ’, studies in intelligence [https://www.cia.gov/library/readingroom/docs/doc_ .pdf], p. ). the oss was excluded from the pacific theatre for most of the war. macarthur’s sceptical approach towards espionage, as well as his bitter personal and bureaucratic rivalry with william donovan, head of the oss, are well known. peter eisner’s book aims to tell a different story. the book is mostly set during the japanese invasion and occupation of the philippines. it follows the lives of three main characters: us army corporal john boone (the soldier), chuck parsons (the spymaster) and claire phillips (the singer). boone is separated from his own unit during the retreat to the bataan peninsula and the island of corregidor. moving to the hills, boone starts developing an embryonic resistance movement against the japanese. parsons (the spymaster) – a us naval reserve intelligence officer – initially poses as a businessman. he is first interned, and later arrested and tortured by the japanese. sent back to the united states he is interrogated by fbi agents who assume he is a spy. finally cleared of any suspicion, he is sent back to australia, this time to work officially as an intelligence officer in the allied intelligence bureau. the ‘singer’, however, is the real star of the book. having moved to the hills to meet her husband, who was serving at the time in the us army, claire phillips finds herself alone. she has to confront both the hardship of life in the hills and the locals’ suspicious attitude towards her and her adopted filipino daughter, dian. finances are tight and prevent her from supporting pows and other us military personnel. for this reason, she decides to establish a nightclub, the ‘tsubaki nightclub’, taking the name of ‘madame tsubaki’. the nightclub is a success with japanese officers, businessmen and filipino collaborationists (p. ). through the nightclub, the money collected and the intelligence gathered, claire strengthens her collaboration with boone. initially, macarthur’s orders for boone’s guerrillas are to stand back and to avoid confrontation with the japanese (p. ). the group, however, start launching ‘hit-and-run’ sabotage operations (p. ). in early , after macarthur’s landing in the philippines, boone reports for duty at the us army base. only then do the guerrillas start a more frontal attack against the japanese. in an interesting note, eisner highlights a letter from boone in which he complains that the only aspect that had not improved was his guerrillas’ relations with the huks, the maoist communist c© the author(s). history c© the historical association and john wiley & sons ltd https://www.cia.gov/library/readingroom/docs/doc_ .pdf modern fighters (p. ). the huks would become the object of a large us counter- insurgency effort led by edward lansdale at the end of the war. the final part of the book follows claire’s life back in the united states, her book and movie deals, as well as her lawsuit in the us claims court. the lawsuit aimed at receiving compensation for the funds she had expended in supporting us forces and the guerrillas. the discovery of the documents from this lawsuit contributed to eisner’s decision to write the book. this section, while colourful, is perhaps less interesting for historians of either intelligence or the second world war. more generally, while claiming to tell the tale of macarthur’s spies, the book says very little about the general up until very late in the war. until then, the soldier and the spymaster have almost no contact with the general. as boone finally joins macarthur’s forces, claire is already back in the united states. the book overlooks the fact that macarthur was sceptical of both the early efforts made by the guerrillas and of what could be achieved through the type of intelligence those units could provide. as laurie wrote, had macarthur been less sceptical, ‘the creation of guerrilla groups ... and the establishment of an efficient intelligence and psychological warfare network ... may have taken place months, if not years, before it actually did in and ’ (laurie, ‘an exclusionary position’, p. ). had that been the case, the singer, the soldier and the spymaster could have been better placed to work with macarthur from the start. ultimately, while a pleasing read, the book works better as a biography of claire phillips than as a history of intelligence and guerrilla efforts in the philippines. swansea university luca trenta how it happened: documenting the tragedy of hungarian jewry. by ernő munkácsi. edited by nina munk. mcgill-queen’s university press. . iv + pp. can$ . . of the many controversies surrounding the history of the holocaust, one of the most persistent revolves around the complicity of non-nazi german individuals, organisations and states in the mass persecution and murder of europe’s jews. the activities of german-allied and german-occupied countries, the comportment of non-jewish ‘bystanders’, and even the conduct of the jewish communities themselves – epitomised by enduring debates on the role of the judenräte (jewish councils) – all continue to capture historiographical imaginaries, spurring reflections on the holocaust’s lasting significance for european societies today. placed at the confluence of such critical debates, ernő munkácsi’s how it happened: documenting the tragedy of hungarian jewry, offers a fascinating and highly significant account of the fate of hungary’s jews between germany’s invasion of hungary on march and the hungarian fascist arrow cross party’s seizure of power on october . written in from the perspective of the former secretary of the chief hungarian judenrat – and expertly translated, edited and commented in this edition by mcgill-queen’s university press – munkácsi’s book further represents a critical, multilayered historiographical attempt to grapple with some of the holocaust’s key questions of culpability, responsibility and agency. c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices as the historian ferenc laczó states in his eloquent contextualising chapter, munkácsi’s book ‘belongs to a somewhat unusual, mixed genre’ (p. xxxiii). writing in his native hungarian language in the aftermath of the second world war, munkácsi aimed to ‘commit to paper certain episodes’ of those critical months in that ultimately saw the deportation of over , jews from hungary, most of whom perished in auschwitz. as munkácsi explains in his introduction, he felt ‘a need – indeed an obligation’ to offer the ‘truth’ and ‘open the eyes of the public to allow a glimpse of historic reality’ (pp. – ). drawing both on first-hand experiences, often presented in a ‘neutral’ third- person narrative, and documents he had salvaged from the archives of the national office of hungarian israelites, munkácsi’s account focuses on the activities of the budapest-based hungarian central jewish council, from its forced inception under adolf eichmann’s authority in march until regent miklós horthy’s abdication in october . munkácsi’s privileged perspective on wartime events, as the jewish council’s former secretary general, constitutes a double-edged sword, as laczó convincingly argues in his opening chapter. on the one hand, munkácsi’s intricate knowledge of the jewish council’s perceptions and actions grants readers profound insight into the distressing balancing act played by europe’s judenräte between complying with and challenging national socialist authority, all in the hope of saving as many jews as possible. on the other hand, munkácsi’s account is steeped in a desire for exoneration. faced both by hungary’s post-war people’s courts, which questioned munkácsi’s wartime conduct (p. lxix), and by mounting criticism among the jewish community, who claimed that he could have done more to save the jews (pp. x, xxxi), munkácsi’s narrative must be read with prudence. how much the council knew of unfolding holocaust atrocities – and ipso facto what should have been done based on this knowledge – lies at the heart of munkácsi’s book, and of larger ongoing debates on the role of the judenräte. as in the accounts of other jewish council officials, munkácsi’s book powerfully illustrates the ‘choiceless choices’ (lawrence l. langer, cited on p. x) faced by europe’s judenräte. installed by order of the sondereinsatzkommando eichmann as ‘the sole organ through which the ss would communicate with the jews’ (p. ), hungary’s jewish council quickly became charged with organising the country’s jewish communities at the behest of the german and, eventually, the hungarian authorities. as such, the council was made responsible, even in the earliest days of the german occupation, for organising forced labour crews (p. ), ‘requisitioning’ jewish apartments (p. ), and providing goods, food and other resources to the gestapo (p. ). the council’s compliance, munkácsi highlights, had diverse origins. on the one hand, many nursed a ‘culpable optimism’ (p. ): particularly ‘the jewish community elders . . . entertained the illusion that hungary would be the exception, a tiny foothold of an island in a sea of jewish devastation’ (p. ), leading to a ‘ruinous’ and ‘infinite naїveté’ (p. ). on the other hand, the council was directly threatened with ‘fatal consequences for the entire jewish community of hungary’ (p. ) should they not comply. working with ‘the germans’, many reasoned, would help stave off the worst (p. ). as munkácsi reveals, attitudes among hungary’s jewish community varied considerably, leading to numerous responses. hungary’s zionists, epitomised by rezső kasztner, drew on international contacts to attempt alijah and emigration c© the author(s). history c© the historical association and john wiley & sons ltd modern (pp. , – ). others, hoping to save their own lives, converted to christianity (p. ). faced by ever more gruesome reports of the deportation of jews from the hungarian countryside and the leaking of the auschwitz protocols (pp. – ), a subsection of the council, including munkácsi, even circulated an underground pamphlet appealing for aid from hungary’s christian citizens (pp. – ). for the most part, however, the council restricted itself to pleading and petitioning for help from the hungarian government, the christian churches and the diplomatic missions of the neutral countries. in some cases – as with the issuing of protective papers through raoul wallenberg’s swedish diplomatic mission (pp. – ) or the deportations’ temporary halt due to horthy’s protest in july (pp. , – ) – such measures seemed to have had an effect. ultimately, however, the jewish council’s actions remained in vain. as munkácsi’s book shows, and as current historical scholarship underlines, the activities and decisions of jewish councils ‘tended to make hardly any difference with respect to the devastating outcomes’ (p. xxx). regardless of the council’s activities, hungary’s jews lay at the mercy of the nazi german and hungarian authorities, the holocaust’s countless henchmen and profiteers, and the large-scale indifference of the christian majority society. how it happened is crucial reading for scholars of the holocaust. as one of the first works on the holocaust in hungary, munkácsi’s text helps dispel the myth that the immediate post-war period was a moment of testimonial and historiographical silence. to some extent both primary and secondary source, the book probes key controversies in holocaust studies, while opening perspectives on the development of the field as such. this english-language edition, furthermore, skilfully contextualises munkácsi’s work by providing a preface by the editor, nina munk, an introductory chapter by ferenc laczó, a biographical essay on ernő munkácsi by susan m. papp, twenty-six telling and carefully commented photographs, a range of expertly drafted historical maps, and a glossary and incisive textual annotations by ferenc laczó and lászló csősz. as such, the book will not only serve as an important reference work on the holocaust in hungary, but will also inspire critical debates on the legacy and historiography of the holocaust more broadly. institut für zeitgeschichte münchen – berlin caroline mezger blue-collar conservatism: frank rizzo’s philadelphia and populist politics. by timothy j. lombardo. university of pennsylvania press. . pp. $ . / £ . . the role of the city, or often the decline of the city, is critical in the transformations of modern political history. the suburbanisation, white flight, ‘busing’, and the fiscal crises of the cities have all received attention in recent scholarship – all contributing to the understanding of the shift from liberalism to conservatism over the decades following the s. despite the modern role of cities as liberal fortresses on electoral maps, the rise of anti-liberalism and later the success of conservatism was forged in the politics of the cities. with blue- collar conservatism, timothy j. lombardo challenges assumptions of modern conservatism as a phenomenon of the south, the sunbelt or the suburbs. the c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices white ethnic anti-liberalism jonathan rieder captured in the classic canarsie: the jews and italians of brooklyn against liberalism ( ) was not restricted to working-class neighbourhoods of brooklyn, but was also central to the modern history of philadelphia. lombardo positions his study of the politics of philadelphia in the decades following the end of the second world war through the character of police commissioner and later mayor frank rizzo, the epitome of blue- collar conservatism. by analysing political, and sometimes physical, battles over education, employment and housing, lombardo is able to provide a comprehensive account of the rise of rizzo as a representative of white ethnic identity politics and populist appeals. the book is divided into two parts, the first covering the transformation ‘from liberalism to law and order’, and the latter focused on ‘the rise of blue-collar conservatism’. the structure, both chronological and thematic, works well. the first half constitutes a fascinating account of how the liberal reform coalition and institutions in philadelphia weakened in the face of widespread opposition to the civil rights movement as their own representatives, such as mayor james tate, came to recognise the emerging electoral clout of anti-liberalism sentiment. frank rizzo, the titular character of the book, is, however, himself largely absent from the first part, or rather looming in the shadows as deputy commissioner. in the second half of the book, rizzo moves into focus as the outspoken police commissioner and later, trading his law-and-order credentials for political success, mayor. still, the book is about philadelphia, not rizzo. the struggles over education, employment and housing are intertwined and reinforce each other as blue-collar conservatism under rizzo’s tenure. following the election of rizzo, the white, blue-collar neighbourhoods behind his success felt in control with a standard-bearer as mayor. at the same time, however, the political influence of the white ethnic identity politics rizzo championed was inexorably waning. the career of rizzo illustrates the potential, and limits, of the white ethnic populism and widespread anti-liberalism of the s and s. when rizzo in campaigned for a change in the city charter to run for a third term, the appeals took on an explicit character. ‘vote white’, rizzo told an audience of supporters and was rewarded with applause (p. ). his s attempt at a political comeback further signals the developments of philadelphia, and national, politics as he abandoned the racial discourses and disavowed his reputation as racist in an unsuccessful effort to appeal to the democratic primary electorate. by , the ‘new rizzo’ and any mea culpas were nowhere to be found in his run as a republican. despite the new party label, rizzo still swept the white, blue-collar neighbourhoods he had built his career on, but could not best the democratic coalition. blue-collar conservatism is an engaging read. lombardo is attentive to the role of racial resentment, even when the archives offer a discourse often deliberately void of explicit mentions of race. ‘[b]lue-collar pride was never a solely innocent expression of pride in place’, lombardo contends, ‘[i]t also functioned as a means of reinforcing racial and spatial segregation’ (p. ). similarly, the author is able to highlight the role of women in the anti-liberalism of modern political history, an aspect of the history of conservatism emphasised by the recent scholarship c© the author(s). history c© the historical association and john wiley & sons ltd modern of elizabeth gillespie mcrae and stacie taranto. lombardo explores how the activism of women, in the roles of mothers in regard to education and housing struggles and the roles of wives in relation to employment, garnered sympathy and media attention. illustrating the importance of the urban north in the rise of populist conservatism, the book is an important addition to our understanding of the decline of the new deal coalition, the strength of urban anti-liberalism, and the influence of white identity politics. ‘liberalism did not just fail in the s,’ lombardo posits, ‘it was actively defeated by blue-collar philadelphians that protested every liberal policy they viewed as an attempt to destroy their cherished institutions’ (p. ). as such, blue-collar conservatism is a necessary supplement to the scholarship on modern american political history, urban history, and the history of both the carceral state and conservatism. åbo akademi university oscar winberg most of th street is gone: the washington, dc riots of . by j. samuel walker. oxford university press. . x + pp. £ . . j. samuel walker examines the rioting in washington dc following martin luther king, jr.’s assassination in april . he explores various issues surrounding the riots, including the economic, social and political conditions, preceding government responses to urban violence in , the costs, victims of the violence, and who were the rioters. this short, but informative, volume draws from official government records, oral histories and archival documents. walker’s preface briefly lays out his five-decade history in the washington dc suburbs, and how he knew little about the city’s history until he began researching the book. the introduction has a short overview of the riots in response to freddie gray’s death in baltimore, maryland, tying it to broader race relations and urban disorder history. walker also highlights the uniqueness of the rioting in washington dc where the military helped to restore order and how it took ten years before large-scale rebuilding of destroyed blocks began. walker begins with an overview of washington dc’s infrastructure, race relations and demographic history until the second world war. in particular, he notes the influx of african americans who fled slave owners during the civil war as well as washington dc becoming the first african american- majority city in the country by . however, employment ‘opportunities were limited’ and housing was ‘inadequate in both quantity and quality’ (p. ). turning to increasing urban unrest in the s around the country, walker describes the violence and government reaction as well as how the news and debates fanned concern about similar violence in washington dc. he also details president lyndon b. johnson’s role in selecting african american leaders of the city and how those leaders, taking office in the autumn of , were dealing with problems ranging from substandard living to the highest per capita infant mortality in the country. c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices king was assassinated in tennessee on april and the reaction in washington dc was immediate with johnson making a televised statement within hours that praised king and called for calm. walker describes the escalation of crowds that gathered at th street and u street into two days of rioting and looting that resulted in destroyed businesses and homes, and showed ‘that black animosity was directed not only at police and firefighters but also at white shop owners, who became the principal targets of the rioters’ (p. ). following the deployment of federal troops in a show of force, order was mostly restored after two days and the imposed curfew was later ended a week after the rioting began. walker notes that in the aftermath of the destruction, the government tried to provide people with needed food, shelter and medicine while thousands of detained rioters ‘flooded’ the justice system with many unable to pay the high bail. turning to media and government analysis on questions about the causes, victims and rioters, walker categorises the explanations for the violence into two groupings. the first argues that a group of agitators or militants ‘incited’ the violence for their own ends, and the second mirrored analysis of earlier urban disorder, which focused on issues such as poverty, inequality and despair. walker provides some examples of perpetuators and victims that do not fit stereotypes and explores how the city ‘learned and successfully applied important lessons’ just months later by preventing large-scale unrest following the end of the poor people’s campaign encampment in june (p. ). closing the book, walker discusses the lack of sustained commitment to reconstruction and revitalisation despite apparent federal and local government interest. one factor, walker notes, was investors’ reluctance to build businesses in the area, which meant that the land remained abandoned and undeveloped. this slowly began to change in the s and s with a new washington metro line and city government building, but the negative aspect of the increased land value was that it raised property taxes for poor residents. as for why the city has not seen any further large-scale violence since , walker cites gains in african american economic and political power as well as greater racial integration in neighbourhoods. yet he cautions that experts ‘all seem to agree on one point – that riots or no riots, the essential ingredient behind the large-scale disorders of the s still exists undiminished in black communities – deprivation and resentment’ (p. ). most of th street is gone is an impressive and concise history of the rioting and its aftermath. nicely incorporating a wide range of primary sources – oral history, official federal and local records and press – walker sheds light on a significant case of domestic unrest in the united states’ capital. in addition, the essay on sources at the end of the book is also particularly strong and could have been included in the introduction as it nicely lays out the historiography and situates the book in the scholarship. there were so many people affected by the riots, including shop owners, soldiers and residents, that more of their voices about their experiences would have added another dimension to the study. if the author had been able to track down these people, not only for their experiences about the events of the week walker analysed in the bulk of the book, the interviews would have also added to the last chapter about how race relations, neighbourhood diversity and african american political power in the city evolved. specifically, these voices would have strengthened his arguments about c© the author(s). history c© the historical association and john wiley & sons ltd modern the changes and continuity of issues impacting the african american community since king’s assassination. nevertheless, this book is highly recommended for scholars interested in urban history, african american history and the history of washington dc. independent scholar ryan shaffer the contest: the election and the war for america’s soul. by michael schumacher. university of minnesota press. . xix + pp. $ . . the tumultuous year still elicits such a range of reaction over fifty years on. for many who lived through it, it was an annus horribilis of violence, tragedy and mayhem. for those more nostalgic for , the year embodied ‘the movement’s’ best and last hope to bring down ‘the establishment’. for those horrified and disgusted with the violence of the s, the year represented an electoral triumph of ‘law and order’ politics over what they interpreted as opportunistic lawlessness on the part of urban black youth and spoiled college kids who had little respect for the authority of their elders. the events of that year are remembered in simple proper nouns – tet, lbj, orangeburg, columbia, mlk, rfk, chicago, and others. the images – saigon police chief general nguyễn ngo.c loan executing viet cong prisoner nguyễn văn lém on a street in saigon; ralph abernathy, jesse jackson and andrew young standing over the slain body of martin luther king, jr., on the balcony of the lorraine hotel in memphis, pointing to the building across the street; robert f. kennedy, lying mortally wounded on the floor of the ambassador hotel’s kitchen in los angeles, tended to so symbolically by juan romero, a seventeen-year-old busboy who had immigrated from mexico as a young boy; jack-booted police beating youthful protesters outside the conrad hilton hotel in chicago – remain seared in the collective american psyche. the presidential election that astonishing year was, as michael schumacher writes, a ‘war for america’s soul’ (p. xi). schumacher, a prolific author, brings an exhaustive yet fresh examination of the presidential election in the contest. organising his narrative in four books – ‘the candidates’, ‘the primaries’, ‘the conventions’ and ‘the election’ – schumacher dissects the election with an engaging style, insightful context and poignant narrative that tells the story from the viewpoint of the participants, as they lived it. he does not allow the now-known future to overshadow the drama of the moment. this approach enables schumacher to capture the human element of these complex events and conflicted personalities. an accomplished biographer (see schumacher’s excellent biographies of allen ginsberg, phil ochs, eric clapton and graphic artist will eisner, for example), schumacher brings his skills to bear on his subjects, namely hubert humphrey, eugene mccarthy, richard nixon, george wallace and robert f. kennedy. schumacher challenges some assumptions about the major players of , allowing some instances for empathy, if only briefly. consider humphrey’s reluctance to step into johnson’s shoes despite preparing his entire political life for the ‘top rung’ of the ladder (p. ); mccarthy’s aloofness hiding deep ambivalence about his decision to run for president; nixon’s tremendous shoulder-chipped ambition juxtaposed to his desire for solitude and family; c© the author(s). history c© the historical association and john wiley & sons ltd https://orcid.org/ - - - reviews and short notices wallace’s racist nationalism against his love and affection for his dying wife, lurleen; and bobby kennedy’s political opportunism against the impact of witnessing poverty in west virginia, meeting with farmers in nebraska and, of course, the murder of martin luther king. schumacher adds humanity to the drama. these were people, admittedly remarkable if not controversial, but people nonetheless, caught in a whirlwind. along the way, schumacher gives a fresh telling to well-known stories, such as that of mark rudd and columbia university president grayson kirk, and david dellinger, abbie hoffman and the yippies in chicago, and johnson’s march speech in which he announced to the nation that he would not seek re-election in . the author also provides an equally fresh look at perhaps lesser-known players, such as michigan governor george romney, mccarthy and kennedy campaign speech-writer richard goodwin, and head of the ‘dump johnson’ movement allard lowenstein. schumacher’s accounts of ‘clean for gene’ volunteers sleeping on cold floors and living on stale peanut butter and jelly sandwiches in new hampshire, of the chaos on the floor of the democratic national convention, and of humphrey and nixon on election day are superbly told. graduate history students should take note – schumacher shows how to weave primary and secondary sources together in a compelling narrative. often lost in academic histories, letting the story tell itself is an art, one that schumacher clearly embraces. this is a well-researched and wonderfully written book. the contest captures the drama and emotion of so many moments as lived by the participants in this incredible election in this pivotal year. did we need another book on the election? apparently yes. and who won the war for america’s soul? the election of revealed that american’s soul is still up for grabs. the contest is an essential read for specialists and generalists alike. georgia southern university william thomas allison risk and ruin: enron and the culture of american capitalism. by gavin benke. university of pennsylvania press. . pp. £ . /$ . . in march the wall street journal reported that jeffrey skilling, the former ceo of enron, had begun to formulate plans for his return to the energy market. this news may well have raised eyebrows, coming as it did after skilling had served over twelve years in a federal prison following his conviction in on nineteen counts of conspiracy, securities fraud, insider trading and lying to auditors. the article suggested that one of skilling’s backers was none other than lou pai, the former head of enron energy services who had made millions of dollars from selling his stock in the company just months before its spectacular collapse. it went on to note that skilling had made over $ million at enron, but it remained unclear exactly how much of his wealth remained after he had paid out at least $ million in restitution and legal costs. as gavin benke points out in his book on enron, popular and media accounts of corporate fraud often rely on the drama provided by the vanity and greed of such flawed personalities. however, the thorny moral issue of individual accountability and white-collar crime aside, readers might also have wondered what skilling’s return to ‘business c© the authors. history published by the historical association and john wiley & sons ltd modern as usual’ might suggest about the meaning and longer-term significance of the enron scandal. how much have the underlying conditions that facilitated enron’s rise and fall really changed? benke attempts to address this question by setting the story of enron within the context of the evolution of american capitalism in the late twentieth century. risk and ruin charts the houston origins of enron and the development of its natural gas business in impressive detail. he describes how the end of the cold war, the rise of what michael goldman has called ‘green neoliberalism’ and the accelerated financialisation of the economy in the late s powerfully shaped the direction and fortunes of the company. benke is a teacher in the writing program at boston university, and his tight focus on the culture of american capitalism is the principal strength of the book. he pays close attention to how the neoliberal lexicon (innovation, creativity, flexibility) created the illusion of infinite growth and fostered positive market perceptions of enron’s stock price. he also uses the company’s marketing literature to illustrate how management theories that were developed in the s and s shaped business culture within the organisation. benke argues that enron chairman kenneth lay’s sunbelt boosterism, his advocacy of deregulation, and perhaps even his close relationship with the bush family, were all manifestations of a broader ideological vision. if neoliberalism is, as timothy mitchell has submitted, ‘a triumph of the political imagination’, then benke demonstrates how business elites can easily be seduced by their own conceit. the most fateful decisions taken by enron’s managers – the adoption of mark-to-market accounting and the proliferation of so-called special purpose entities – are best understood within this cultural framework. the book is therefore primarily concerned with the fashioning of business narratives and how these contribute to our understanding of the enron scandal. benke does dedicate some space to describing the role of enron in california’s energy crisis in and . he also reports the failure of rebecca mark’s grand development projects in india and elsewhere. however, he is overall less concerned with addressing the political and material effects of enron’s global business. scholars interested in these aspects might choose to read benke’s book in conjunction with derrick hindery’s work on the cuiabá pipeline in bolivia. as for the long-term effects of the enron scandal, benke suggests that it offered an unheeded warning to america’s political elite. not all readers will be fully persuaded by benke’s thesis that enron’s troubles were symptomatic of wider systemic failures. some may even consider that the sarbanes-oxley act was a sufficient regulatory corrective to an isolated episode of corporate fraud, one that was ultimately caused by ‘a few bad apples’. benke, however, argues that the fiasco presaged the much larger crisis that engulfed the global financial system in . he points out that following the enron bankruptcy alan greenspan declared that it was the proliferation of financial innovations such as credit default swaps and other complex derivatives that had blunted the impact on the wider economy (p. ). an opportunity to question the prevailing wisdom of the day, the supposed perfection of the market, was overlooked. risk and ruin is a clear and concise account of the enron story, and will be useful to business historians and those interested in corporate governance, financial regulation and the energy industry. however, it also attempts to situate the particularities of enron’s corporate culture in relation to the wider political and economic dimensions of the ‘new economy’. as such, it is a welcome and c© the authors. history published by the historical association and john wiley & sons ltd reviews and short notices valuable addition to the rapidly growing literature on the history of american capitalism. university of cambridge richard saich general suffering and happiness in england – : narratives and representations. a collection to honour paul slack. edited by michael j. braddick and joanna innes. oxford university press. . xii + pp. £ . . there are eleven contributors to this volume presented to paul slack, including three of his doctoral students. the title invites considerable expectations. all those writing here come from the generation of oxford undergraduates when slack’s influence was strong there. his well-known authority on plague and his more recent account of ‘the invention of improvement’ in made the theme chosen one with obvious appeal to many who have applauded his long mastery in this field. in his ford lectures in , slack drew our attention to ‘the ways in which people who sought to change society expressed their intentions’. in a article, he wrote about happiness in the later seventeenth century, showing himself as one of the first to engage historically with this crucial aspect of all our lives. the book begins with ‘grand narratives’. alexandra walsham is at her most scintillating in discussing suffering, in terms of ‘adversity, providence and agency in early modern england’. as we would expect, she has all the material at her fingertips. the editors suggest this section of the book concerns ‘worlds, discourses and theories’ over time, looking at how each ‘was associated in more or less indirect ways with emotions’. phil withington considers the evolution of usage of the words ‘happiness’ and ‘felicity’ between and on eebo, showing how ‘happiness’ was the one that triumphed from around the s or s. the invention of happiness, in his reading, had a prolonged history, though one confined within the period of this book. picking up walsham’s and withington’s themes, craig muldrew provides a cogent history of the development of self-consciously philosophical thought and argument in work on the self in late seventeenth-century england. joanna innes, exploring ‘happiness contested’, argues that happiness denoted ‘an individual feeling or a social experience, a spiritual state or political imperative’. in the eighteenth and early nineteenth centuries happiness ‘remained pre-eminently a name for a desirable condition, naturally productive of positive feelings’. an international conversation about government and society emerged ‘framed in terms of happiness’. david hume and hannah more among others came into the question; then malthus’s arguments ‘threw various established schemes of analysis into disarray’. when the book turns to suffering in detail, it becomes more problematic. michael braddick’s account of john lilburne’s sufferings and their representation is acceptably a straightforward essay in a careful source-based analysis. faramez dabhoiwala’s treatment of petitioning, in its content perfectly respectable, misses the conception of the book. so does tim hitchcock’s study of ‘death, burial and belonging in georgian st giles in the fields’. lilburne’s story apart, these three c© the author(s). history c© the historical association and john wiley & sons ltd https://orcid.org/ - - - general chapters do not, as was intended, explicate ‘mobilising suffering and happiness’. if the book seems about to lose its way, mark knights’s biographical study of james bovey from to hardly allows us to put aside the danger of its doing so. but sarah lloyd’s chapter on poverty and happiness in the eighteenth century shows her as a new star in the making, in her sympathetic grasp of the field of charity and poor relief. her new angle on happiness, she convinces us, repays much fuller investigation. this leaves us with two more chapters on ‘experiencing suffering and happiness’. sarah pennell asks about the potential for ‘happiness in things’. she plunges boldly into emotional engagement and the process of consuming, hailing recent work by peter king, craig muldrew and adrian green. but she concludes that historians have found ‘knowledge of domestic material environments . . . especially sparse or terse’. take the issue of security, ‘fundamental to intellectual, moral and legal explanations . . . of the origins and development of all rights in property’. pennell is disappointed by amanda vickery’s discourse on locks, keys and window shutters in her behind closed doors. yet we might expect this volume to celebrate the work of a historian who, more than most, has tackled possessions in terms of the history of emotions. pennell hopes to illuminate the book’s themes by taking us back to the relationship between security and stability. thus she provides a learned and thoughtful review of chattel distraint, declaring that this ‘framed a georgian conception of indebtedness . . . as a providential state of being to be pitied and exemplified’. perhaps alexandra shepard is one of the few contributors here who seems fully on top of the task the editors have set. hers is a closely argued analysis of the ‘pleasures and pains’ of breastfeeding. this, she believes, was an area where ‘emotional finesse trumped good health and experience’. the ‘fine lady’ should perform her maternal role, because it was beneath her substitutes, who were claiming to perform it for her. the editors confess in the introduction that they found the book ‘challenging as well as stimulating’. they found themselves faced with a diversity of contributions. they see the history of emotions as a ‘crossroads or market place in which many historians’ paths may fruitfully cross . . . rather than any kind of bounded community’. they regard this book as a ‘point of encounter’, for historians with ‘diverse knowledge, interests and skills’. this looks like a degree of special pleading. congratulations to the editors on preserving paul slack with these preliminary ‘narratives and representations’ that bear upon suffering and happiness in this exciting field of burgeoning historical effort. moreton-in-marsh anthony fletcher a thirst for empire: how tea shaped the modern world. by erika rappaport. princeton university press. . xiv + pp. £ . . as karl marx memorably observed in the first volume of das kapital, the commodity is a very mysterious thing. nevertheless, ever since sidney mintz published his seminal work on the history of sugar, sweetness and power, more than three decades ago, historians have rendered many commodities considerably less mysterious, producing detailed studies of their multiple histories and forms c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices of representation. erika rappaport’s authoritative and multi-layered history of tea, which combines a sure grasp of existing work in the field with an immense amount of meticulous archival research across different countries and continents, is the best account by far we have of this key commodity. the general story that rappaport tells is familiar enough. it has after all been told many times before, not least by growers, manufacturers and retailers themselves, who have been keen to promulgate romanticised narratives to help boost sales. the historical reality of course involved the political intrigue and violence that invariably accompanied capitalist development in the modern world. the dutch, french and portuguese introduced the british to the delights of chinese tea in the seventeenth century, but the british soon came to dominate the global trade, especially after the british east india company entered the scene in the s. promoted as a cure-all, tea drinking became a defining feature of genteel sociability during the second half of the eighteenth century, though plebeian consumers also enjoyed a brew as prices fell. british traders exchanged opium for chinese tea and kept markets open with the help of british naval and military power, but they also sought alternative sources of supply. therefore, from the s, planters bloodily appropriated land and grew tea in assam, although it took over half a century to alter consumers’ taste in the metropole, only achieved after advertisers had spread messages about the adulterated, foreign nature of green chinese tea and the superiority of the patriotic black ‘british’ variety. from the fin de siècle, an international group of planters protected and furthered their interests through powerful trade bodies such as the indian tea association, founded in , which advertised globally and lobbied governments. tea thereafter lodged itself firmly in the national psyche, helping to keep spirits up during the great depression and the second world war. decolonisation forced a rebranding of tea, shifting it away from its imperial and patriotic roots towards affluent young consumers who from the late s were being increasingly seduced by the allure of the espresso. tea consumption fell inexorably thereafter, a decline that even the tea bag and advertising chimpanzees failed to arrest. despite such vicissitudes, tea has remained a quintessential signifier of ‘englishness’, as the jamaican-born british sociologist stuart hall pointed out: ‘i mean what does anyone in the world know about an english person except that they can’t get through the day without a cup of tea? where does it come from? ceylon-sri lanka, india. that is the outside history that is inside the history of the english.’ by skilfully interweaving the broader history of the tea trade with a number of fascinating, apposite case studies, rappaport throws considerable light on the ‘outside history’ inside, demonstrating in rich detail how processes of capitalist consumerism and imperial expansion were inextricably intertwined. she also shows how tea was freighted with multiple meanings from the beginning: eighteenth-century pamphleteers like john waldron bemoaned its supposedly feminising effects; temperate middle-class and working-class victorians thought the tea party pointed the way towards a higher moral and economic order; critics of adulteration stoked racial fears in their campaign against chinese green tea; while merchants like john horniman attempted to quell anxieties by advertising the purity of packeted, branded goods. one of the most engaging chapters in the book shows how, in the late nineteenth century, planters and retailers transformed the preference of consumers – for whom black tea had been initially too c© the author(s). history c© the historical association and john wiley & sons ltd general bitter – by means of extensive advertising and publicity stunts such as exhibitions. drinking empire-grown tea soon became a private and public craze; london alone had around , teashops in . by the interwar period, british planters enjoyed a near monopoly of the global tea trade, although they were threatened in some markets by rivals including the chinese and dutch east indian teas. again, they responded with patriotism, employing the agency head sir charles higham to lead the fightback, although he failed to turn america into a nation of tea drinkers, a market survey of remarking that tea was still regarded in that country as ‘a woman’s drink, unfit for and unworthy of a man unless he is a sissy’. again, the continuing metonymic resonance of the humble cuppa is striking. in this fine-grained work, rappaport demonstrates what can be achieved by studying a single commodity in great depth, tracking it through circuits of production, distribution, exchange and consumption, carefully reconstructing the ways in which it has been represented and the different meanings that have been assigned to it across time. inevitably, perhaps, there are limitations. the work tells us a great deal about how the mobile planter raj, their trade associations and advertisers saw the world, but it tells us relatively little about those who were forced to labour in the euphemistically named tea ‘gardens’, which were more like slave plantations. however, this should not detract from the value of a work that brings to life so vividly a commodity whose singular history played such an important role in constituting global capitalism. university of essex peter gurney american naval history: a very short introduction. by craig l. symonds. oxford university press. . xx + pp. £ . . this work is one of the latest in oxford university press’s ‘very short introductions’ series, which now runs to over volumes. the work comes in at pages plus another pages of references, further reading and index. the series states that it is for anyone ‘wanting a stimulating and accessible way into a new subject’; when the preface (p. xix) refers to ‘the quotidian activities of a constabulary navy’ one briefly has doubts, at least about the accessibility, but thankfully this rather dense bit of language is a solitary instance. beyond its historical narrative, the work has two underlying themes: firstly, the argument between the navalists (who wanted a large fleet) and the fiscalist sceptics and secondly, the changing culture of the navy and how this has reflected america’s changing society more generally. the first of these themes is referred to until the navalists prevailed, symonds dating their victory to precisely and attributing it to three developments. the first of these is the congressional decision to build three new battleships, which importantly were constructed primarily to defeat other battleships. a further development cited by symonds is the publication of the us census report indicating that the western frontier had disappeared. he argues that this suggested that ‘america’s future growth might extend beyond the boundaries of her continental limits’ (p. ). the other development flagged by symonds is the publication of alfred thayer mahan’s seminal work the influence of sea power upon history – . c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices this was an analysis of how the small country of great britain had built a global empire, through the command of the seas achieved by its battleship fleet, from which then flowed trade, wealth, power and military dominance. symonds says that mahan ‘presented this remarkable achievement as a kind of blueprint, appending a general introduction to the book that itemized the preconditions of naval dominance implying (at least) that nations possessing these characteristics could duplicate britain’s rise to power’ (p. ). the exact influence of mahan’s work upon the development of the american navy is perhaps yet to be fully explored but its influence on european powers such as great britain and germany is well known and was indeed recognized very quickly. sir william laird clowes stated in (in the general preface of his seven-volume work the royal navy: a history from the earliest times to ) that mahan had ‘applied the teachings of the past to the possibilities of the present and the future’. it does seem likely that mahan’s book had a similar impact in the united states. the navy’s reflection of america’s changing society is shown throughout the work, symonds tracing its evolution from largely illiterate international crews to an educated, enlisted force representative of the heterogeneous character of the american population and an officer corps populated by men and women of every race and religion. in an avowedly short work such as this, a significant issue is what to omit, but this reviewer has no argument with any of the major decisions made by the author. there are, however, a few places where a little extra detail would have helped. on page , we are told that stephen decatur sailed into tripoli harbour and burnt the captured frigate philadelphia, without the fact or the circumstances of her capture having previously been mentioned (in fact she ran aground on an uncharted reef two miles outside the harbour while chasing a pirate ship). nelson apparently hailed decatur’s feat as ‘the most bold and daring act of the age’, praise that would surely have been worth including in the book. on page , decatur then appears off algiers to demand the dey’s acceptance of a new treaty, but we are not informed of the outcome. in the civil war chapter, a map would have helped, to illustrate both what came to be known as the anaconda plan to strangle the confederacy with a naval blockade and then subsequent actions in the war. lastly, on page , dealing with the cuban missile crisis, the ‘naval quarantine’ is mentioned and then that the soviets eventually agreed to remove their missiles from cuba. the impression could thus be gained that the quarantine had achieved this outcome, whereas in all probability it was the imminent prospect of american invasion and the consequent possible escalation to nuclear war that focused minds on the eventual diplomatic solution. a sentence or two on the navy’s preparations for the invasion might have been useful here. there is only one quibble with what is actually in the text, napoleon being stated (p. ) as having been defeated at the battle of the nations (leipzig) in whereas that battle was, in fact, in . in conclusion, this work does exactly what it says on the tin, being indeed very short but at the same time stimulating and accessible, even for those who already have some knowledge of the subject. independent scholar richard dowling c© the author(s). history c© the historical association and john wiley & sons ltd general before the refrigerator: how we used to get ice. by jonathan rees. john hopkins university press. . x + pp. $ . . rees’s short, entertaining book is part of the johns hopkins university press ‘how things worked’ series and will be of interest to those working on late nineteenth- and early twentieth-century united states history. although it focuses on one industry in depth, this is an industry often neglected by scholars of economic history in favour of examinations of steel, coal, cotton and other prolific outputs of the united states during the gilded age. rees shows how the changes in technology, transportation and business practices in this one sector reveal important aspects of economic and social history. this book takes as its fascinating focus the ice industry, tracing its low-tech origins in early nineteenth-century boston, when expansion and innovation were triggered by demand for the product in bars and taverns and for preservative uses in meatpacking. rees argues that, over the subsequent century, this neglected industry changed diets by ending seasonal and regional variability and driving food prices down for the lower and middle classes. technological change transformed the industry over the century prior to the first world war, as, once artificial ice had replaced the natural form, the size of the first commercial ice-producing machines reduced significantly. this was a fast-moving industry, as both merchants and consumers were willing to accept change, and without a dominant player, the industry was decentralised and favourable to entrepreneurship. the first business in the ice industry was run by frederic tudor who, in , shipped ice from boston to martinique, losing money but learning about new methods in the process. but it was during the third quarter of the nineteenth century that ice shipments expanded most significantly with , tons leaving boston in compared to million tons per year by the s. while natural ice still dominated, during the s an ice rush in maine saw renewed interest in the commodity. further west, wisconsin ice was valued by brewers such as pabst, as well as the chicago meatpackers. but by the s the first ice machines had appeared and, although initially their ice was of poor quality, the decline of natural ice was inevitable. by the turn of the century there were large ice plants in many southern cities. an attempt to establish an ice trust to protect the natural industry produced only a short-term revival, and from onwards the market shrank. after the first world war, ice producers’ imperative was ‘shortening the cold chain’ (p. ), meaning that the ice was manufactured much closer to where it was required. the men who sold this new artificial ice had an unwarranted reputation in popular culture for dishonesty and lack of cleanliness. these changes in the ice industry revolutionised food cost and availability. beef, fish and fruit became national commodities and thus ended poor health caused by winter diets short in vitamins. milk also became a safer product to consume because it could be kept fresh for longer. this period of ice manufacture, warehousing and distribution itself lasted only a short time as personal refrigeration devices became popular, but it took until the middle of the century before they finally changed the ice market irrevocably. the first electric fridge was produced in and, despite ice companies emphasising the fridge’s lack of reliability, many in the industry saw change coming and entered the ice box or air conditioning markets. following the activities of the new deal towards c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices electrification of rural areas, by the end of the second world war, per cent of american homes had a fridge and few still relied on ice deliveries. in the twenty- first century, the size and ice-producing capacity of one’s fridge is an important status symbol. rees’s work is eminently entertaining and accessible. i recommend it as a case study for students of the history of the modern united states, and to anyone interested in aspects of social and economic history told from the perspective of the unusual and unique. loughborough university catherine armstrong debating genocide. by lisa pine. bloomsbury. . xiv + pp. £ . . ever since genocide studies emerged as an independent field in the s, scholars have worked to systematise the knowledge about this particular international crime. about ten years ago the field itself came under scrutiny. the present book is yet another attempt to provide a comprehensive introduction suitable for the classroom. the result is rather mixed, and the fault to a large extent lies with the framework within which genocide studies operate. the way pine goes about discussing the rapidly evolving field of genocide studies and its intended outcome suggests quite the opposite. the book prompts more questions than it answers. the book begins with the concept of genocide and continues with selected case studies. among the many aspects of genocide, pine chose to focus on gender, prevention, justice and memorialisation. she also briefly touches on environmental degradation. pine demonstrates a solid grasp of the literature when outlining particular instances of genocide. to what is a standard selection of cases, pine adds colonial genocides and premeditated mass violence in sudan’s darfur region. the former chapter, which looks comparatively at north america, the congo free state, german south west africa and australia, is also the most judiciously argued. pine insists that, in spite of an inbuilt element of racialised violence, colonialism should not be automatically associated with genocide. instead, she considers coordinated attacks against specific tribes, which did indeed on occasion amount to genocide. the chapter on darfur is quite comprehensive, too, except that it does not account for the long-lasting civil war in south sudan and has little to say about the present situation. understandably, pine had a difficult choice deciding which cases to include in the book. thus, she opted to introduce a separate chapter on the nazi genocide of the roma – which she sees in isolation from the holocaust, despite a critical mass of empirical evidence to the contrary – but to exclude the soviet terror. the latter decision strikes one as odd, especially since pine goes on to examine communist cambodia. furthermore, one of her questions to the prospective student is to compare and contrast mass violence in pol pot’s cambodia and stalin’s russia. all in all, pine does not link individual cases of genocide effectively. whenever pine emphasises commonalities between different instances of genocide, she does it at a rather superficial level (p. ). c© the author(s). history c© the historical association and john wiley & sons ltd general in her discussion, pine adopts the deterministic approach common to genocide literature. throughout the book she uses constructs such as ‘genocidal possibilities’, ‘genocidal measures’, ‘genocidal violence’, ‘genocidal campaign’, ‘genocidal cause’ and ‘génocidaire’. perceiving genocide as a normative act, pine keeps referring to certain instances of genocide as ‘classic’ or ‘paradigmatic’. that ties up with her assertion that genocide is a historical process (p. ) but goes against the grain of her earlier discussion on ‘competitive hierarchies’ (p. ). when pine refers to ‘scholars in the field’, she invariably means genocide studies, to the exclusion of those academics who do not deal with genocide per se. to give just one example, historian david chandler, a recognised expert on cambodia cited at length by pine, has resisted being drawn into the debate on whether or not the khmer rouge committed genocide. the organisation of the book leaves a lot to be desired. the centrepiece of the book – current debates in genocide studies – sometimes is rendered as a single quote from a certain author or the juxtaposition of one scholar arguing one thing and others disagreeing. on occasion, the thesis encapsulated in a book title stands for an entire argument (as with karl schleunes and the twisted road to auschwitz). this is just one of many discursive fallacies in the book. far too often, pine picks an earlier hypothesis on the cause of mass violence (typically advanced by journalists as the conflict flares up, for example, the thesis of perpetual ethnic hatred) and expertly dismantles it in reference to subsequent scholarship. it also happens that pine takes a particular historical interpretation as an affirmation of fact (pp. – ). another rhetorical device pine is unwittingly using is to present recent trends in scholarship as the ultimate truth in what might not even constitute an informed debate. for instance, there are several books that attempt to link the german extermination of herero in africa and jews in europe (p. ). however, no credible evidence has emerged so far that the nazis fell back on this particular instance of colonial violence when conceiving of the final solution of the jewish question. sometimes pine presents the issue of genocide as central to the whole complex of mass atrocities committed, for example, in the former yugoslavia (p. ). at other times pine makes a debate that has since long been superseded (for example, the relationship between the notion of holocaust and genocide) sound current. at the same time, what pine on occasion dubs ‘neglected’ or ‘forgotten’ genocides (targeting such minorities as the armenians or the roma) became public knowledge decades ago. perhaps most crucially, pine fails to convince why the study of genocide versus other forms of mass violence is so important. her argument features a good deal of tautology. debates about genocide are important, says pine, because genocide stalks human history. it is incomprehensible why genocide but not, say, war crimes or crimes against humanity should raise ‘our concern for humanity and our sense of justice and morality’ (pp. , ). pine’s discussion on gender and genocide is quite refreshing, though not entirely unproblematic. as pine admits, empirical evidence is inconclusive as to the chain of command or specific intent to use mass rape as a means of genocide. the discussion of prevention underlines the innate contradiction within genocide studies. while genocide prevention remains the field’s unspoken raison d’être, pine concedes that implementing it in practice has proved next to impossible. c© the author(s). history c© the historical association and john wiley & sons ltd reviews and short notices here she specifically refers to the original promise and ultimate failure of the un responsibility to protect initiative. and if prevention should apply to all atrocity crimes and not exclusively genocide – as pine concurs with one of the scholars – what is the point of having genocide studies as a distinct field? the field of comparative studies may indeed be fast growing, as pine says, except that it does not have a sense of direction. by insisting that the debates on the definition of genocide are crucial for the understanding of genocide (p. ), pine is back at square one with her entire discussion. i would argue that we have tried that for almost thirty years now, without anything much to show for it. the norwegian center for holocaust and minority studies anton weiss-wendt c© the author(s). history c© the historical association and john wiley & sons ltd august , volume , number american association for the the advancement of science science serves-its readers as a forum for the presenta- some tion and discussion of important issues related to the ad- decade vancement of science, including the presentation of mi- nority or conflicting points of view, rather than by pub- populat lishing only material on which a consensus has been food prreached. accordingly, all articles published in 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( - - ). advertising correspondence: tenth floor, culties broadway, new york, n.y. . phone: - inaccurn - . science ?llobal report e parts of the world will probably reach limits to growth in the next or two. the reasons are well known-a percent annual increase in tion leads to a doubling in about years. such a rate of increase in roduction cannot be sustained indefinitely. the problem has been many times, including studies by the club of rome. on july the government got into the act with a report of about pages entitled obal report to the president. may president carter called for "a one year study of the le changes in the world's population, natural resources and environ- rough the end of the century." the council on environmental qual- the department of state were designated as lead agencies and were ized to call on other appropriate federal agencies for assistance. a of portions of the report produced after years reveals more about ctioning of the federal government than it conveys new reliable infor- about the future of the world. e of the agencies responded quickly while others were slow. thus, the material is outdated. the energy projections were made in ing of before the iran crisis. at that time oil prices seemed stable it $ a barrel. accordingly, the department of energy (doe) made ions of energy use on the basis that, in constant dollars, the price remain $ a barrel until . the drastic change that occurred in )es largely unrecognized, as does the current sharp decline in u.s. iption of oil. in the common view was that oil production would e to increase until it peaked in about . but experts are now that the peak probably occurred in . the material also contains two other significant errors. the oil in place at athabasca and other ions in the region is now estimated at to billion barrels (the- xoe figure was billion barrels). that in venezuela is placed at to billion barrels (the doe estimate was billion barrels). apter on environmental projections has a section on "the use of als in the development of societies" in which one of the state de- nt employees provided this gem: "it was not until the end of the th that the use of chemicals in society began to become wide- .... this development coincided with the discovery that crude could also be used as a new source of supply of chemicals. a new .ic discipline emerged, to expand the utility of crude oil: organic try." in point of fact, organic chemistry began in with wohler. 's the german chemical industry was a billion-dollar-a-year en- (in dollars). it was producing a great variety of organic chem- ncluding dyestuffs from coal tar. use of petroleum as a feedstock important only in the 's. restation is very serious in parts of the world. however, the author hapter on forestry has made questionable statements about the ama- lley. he quotes an estimate that the area is being deforested at the percent a year, with half the forest to be removed by . my lnt at the brazilian embassy scoffed, "has the man flown over the in?" he went on to state that road-building there has almost i-the energy crisis has caused a shift in priorities. report has other deficiencies of analysis and consistency. it projects led fast growth in gross national product in less-developed countries ) without adequate discussion of the impact of sharp increases in the f oil. it projects virtually unchecked population growth in ldc's and onding increases in food production while emphasizing losses in id due to desertification, deforestation, water logging, urbanization, ilerosion. report is correct in emphasizing that the world faces decades of diffi- and some of its sections are well done. but outdated material and, acies detract from its value.-philip h. abelson o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ the global report philip h. abelson doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the trademark of aaas. is a registeredscienceadvancement of science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for thescience science. no claim to original u.s. government works. copyright © the authors, some rights reserved; exclusive licensee american association for the advancement of o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ new gen controlling variable using dragonfly algorithm in pv panel energies article new gen controlling variable using dragonfly algorithm in pv panel shabana urooj , fadwa alrowais , ramya kuppusamy , yuvaraja teekaraman ,* and hariprasath manoharan ���������� ������� citation: urooj, s.; alrowais, f.; kuppusamy, r.; teekaraman, y.; manoharan, h. new gen controlling variable using dragonfly algorithm in pv panel. energies , , . https://doi.org/ . /en received: december accepted: january published: february publisher’s note: mdpi stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. copyright: © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (https:// creativecommons.org/licenses/by/ . /). department of electrical engineering, college of engineering, princess nourah bint abdulrahman university, riyadh , saudi arabia; smurooj@pnu.edu.sa department of computer sciences, college of computer and information sciences, princess nourah bint abdulrahman university, riyadh , saudi arabia; fmalrowais@pnu.edu.sa department of electrical and electronics engineering, sri sairam college of engineering, bangalore city, bengaluru , india; ramyapks @ieee.org mobi- mobility, logistics and automotive technology research centre, evergi, vrije universiteit brussels, ixelles, belgium department of electronics and communication engineering, audisankara college of engineering and technology, gudur , india; hari prasath@gmail.com * correspondence: yuvarajastr@ieee.org abstract: in the present scenario the depletion of conventional sources causes an energy crisis. the energy crisis causes load demand with respect to electricity. the use of renewable energy sources plays a vital role in reducing the energy crisis and in reduction of co emission. the use of solar energy is the major source of power in generation as this is the root cause for the development of wind, tides, etc. however, due to climatic condition the availability of pv sources varies from time to time. hence it is essential to track the maximum source of energy by implementing different types of mppt algorithms. however, use of mppt algorithms has the limitation of using the same during partial shadow conditions. the issue of tracking power under partial shadow conditions can be resolved by implementing an intelligent optimization tracking algorithm which involves a computation process. though many of nature’s inspired algorithms were present to address real world problems, mirjalili developed the dragonfly algorithm to provide a better optimization solution to the issues faced in real-time applications. the proposed concept focuses on the implementation of the dragonfly optimization algorithm to track the maximum power from solar and involves the concept of machine learning, image processing, and data computation. keywords: dragonfly optimization algorithm; maximum power tracker; pv panel . introduction in the present situation the upcoming problems in the real-time environment is in- creased compared to the past situation. this led the present researchers to develop more effective solutions by means of optimization technique. the extensive search of these optimization techniques led the researcher to develop sustained solution by understanding the natural characteristics of swarms in nature. many algorithms were developed by many of the researchers by understanding the characteristics, behaviors, reactions, and properties of swarms in nature. the upcoming research in the real world applications is the use of methodologies inspired by nature. the use of methodologies needs intel- ligence in computational techniques to solve complex problems. the ict (intelligence in computational techniques) involves ann (artificial neural network), fls (fuzzy logic system), and mla (multi-layer algorithm). the ict addresses the real-time application issues that involve discrete or continuous time problems or combination of both. the recent trend in computational process is the use of si (swarm intelligence) and the algo- rithms developed using si attracted many researchers to develop solutions for complex energies , , . https://doi.org/ . /en https://www.mdpi.com/journal/energies https://www.mdpi.com/journal/energies https://www.mdpi.com https://orcid.org/ - - - https://orcid.org/ - - - x https://orcid.org/ - - - https://orcid.org/ - - - https://doi.org/ . /en https://doi.org/ . /en https://creativecommons.org/ https://creativecommons.org/licenses/by/ . / https://creativecommons.org/licenses/by/ . / https://doi.org/ . /en https://www.mdpi.com/journal/energies https://www.mdpi.com/ - / / / ?type=check_update&version= energies , , of engineering real-time problems. the methodology is used to ensure the solutions in sia are fast, robust, and flexible [ ]. the biological sensing network and the concept of neural system is the great motivation in developing the si based algorithm and each of these types of algorithm, resembles the natural behavior of animals and swarms. among different types algorithm framed by si (swarm intelligence), pso (particle swarm optimization) proposed by kennedy and eberhart is the most popular type. in this, many agents together form a population and each agent in the population interacts with the naturally-framed systems and the environment [ , ]. marco dorigo developed a thesis and examined the optimization process using aco (ant colony optimization) a nature-inspired algorithm [ ]. the multi-objective optimization has many issues and the set of issues framed in moo is a pos (pareto optimal set), and these sets have better trades in between the objectives. the moo algorithm is developed and carry forward to obtain the complete solution under the worst and best conditions of the current pos. the solution to pos is obtained by means of iteration and the probability of each set of iteration is utilized for process selection [ ]. power can be generated either by using conventional/non-conventional sources. the use of conventional sources for generation increases co emission and the depletion of conventional sources causes an energy crisis. to avoid the energy crisis and to reduce the effect of co emission nces (non- conventional energy sources) is utilized for power generation. solar is the main source of nces as it is the main root source for the development of wind and tides. the use of solar for power generation varies from time to time due to the variation in ecological conditions. therefore, maximum power has to be absorbed from the available source. this is done by using a smart tracking technique. among the available different tracking techniques the p and o mppt (maximum power point tracker) tracker is highly efficient. for varying irradiance variable p and o mppt is discussed in [ ] to track maximum energy. the variable p and o comprises of an amalgamation of current and adaptive perturbation control techniques. the adaptive technique implied in mppt fix the operating point in terms of pv source operating current and irradiance to validate the performance and stability under dynamic conditions. the genetic technique is implied in the mpp-p and o algorithm to trace the power under different ecological conditions and partial shadow conditions [ ]. hadeed ahmed sher proposed the tracking technique, which implies the combination of a short circuit method and a conventional p and o technology, named as fractional mpp with p and o and short-circuit current algorithm. in this the pv source short circuit current is taken as a reference to fix the operating point and, later, it is followed by the conventional p and o mpp [ ]. the v-i and p-v characteristics of pv is non-monotonic. during the complete h in a day there are many local points to trace the maximum power. a novel technique is proposed to search the point of maximum energy in the overall distribution of power. pso is one such technique to develop this novel overall distribution algorithm [ ]. the peak point of power available in a day has a multi-objective function. among these multiple peak-point pso with p and o is proposed to fix one operating point among the global power points [ ]. the recent computational technology implemented in control action involves swarm intelligence. the system performance and its efficiency are affected with the discrete behavior of the swarm particles. in [ ] the pso with swarm particle algorithm is proposed to improve the transformation and crossover operation of the system. the proposed concept in this paper focuses both on single- and multi-objective problems. the pso algorithm comprises of ‘n’ dimensional membership variables and each variable has been assigned with its own weight depending on the velocity. in [ ] during the process of evolution of each of the individual flies, the solution to the optimization issue is resolved by frequently updating the weight based on the velocity and position. the best optimization solution is obtained in [ ] with a uniformly-distributed random vector, and . in [ ] the non-linearity and the complexity of the problem is addressed with the recent approach of involving the characteristics of swarm particles. this algorithm is proposed as it is flexible and simple to implement. the challenging problems are addressed in this manuscript. energies , , of the da (dragonfly algorithm) is a unique solution for better optimization. the recent technologically-advanced empirical optimization procedure is the dragonfly by mirjalili. the proposed algorithmic procedure in [ ] has exposed its ability to address various real-world issues. the algorithm in [ ] is proposed with the natural flying behavior of dragonflies and it implies the concept of lfm—levy flight mechanism. the use of lfm has cons, such as the swarming of the search area and disruption of nonsystematic flights. this paper proposes the da algorithm study known as brownian motion, which improves the randomization stage of the da. in the work proposed earlier, for any variation in the geographical condition and any variation in atmospheric situation, the output from a solar pv system varies abruptly. this causes fluctuations at its output and the dynamic response and the system efficiency is going to get affected very badly in [ – ]. hence, to track the maximum amount of power many methods and algorithm have been proposed. however, swarm optimization is one of the best methodologies to be implemented in solar pv systems to trace the maximum amount of power. though we have many more swarm optimization technologies, like pso and firefly, the proposed dragonfly in mppt produces the best result in terms of tracking the maximum power under all conditions. this includes partial shading conditions, as well. the proposed work identifies and incorporates a new controlling variable along with the dragonfly algorithm in mppt to track the maximum amount of power under all conditions. the concept of randomization is considered to be an important factor in optimization to solve the issues effectively. the random movement of the particle ensures that there are many ways to solve the problem. the solution obtained in optimization can be even more accurate by increasing the number of iterations. if the concept of randomization is not considered then the optimization is analyzed only in the confined region. to improve capacity of the concept at each and every point in space, the concept of randomization is important. the lfm is the new method that provides solution to hybrid optimization algorithm. in [ ] the author proposed the lfm technique to analyze and validate the concept of a stochastic algorithm theoretically to obtain the global optimization. the algo- rithm examined in [ ] proposed the concept of optimization towards the transmission of light. the author in [ ] implements the concept of lfm in a cuckoo search technique that depends on the parasitic behavior of certain cuckoo classes in combination with the behav- ior of lfm. in [ ] the firefly algorithm is adapted in lfm, and proved that the proposed one is superior in system performance when compared with the existing algorithm. for estimating the parameter in non-linear dynamics the bat algorithm technique is proposed along with lfm in [ ]. the dragonfly algorithm concept is proposed by [ ] to improve the result of optimization from its initial random population and converge towards global optimization. . dragonfly algorithm in pv system the dragonfly algorithm developed by [ ] is one of the best optimization techniques that involves nature-inspired algorithms. the da (dragonfly algorithm) originated from the swarming behavior of flies under static and dynamic conditions. exploration and ex- ploitation are the two basic behaviors of swarming particles. the movement of dragonflies are isotropic in nature and it is modeled using lfm. the movements of the flies are random in nature and the distance it moved can be small or large. if the flying behavior overflows, and if any distance gets interrupted due to the movement of the flies to a larger distance, the use of lfm causes disadvantages due to larger searching steps. the concept of the dragonfly is implemented in the mppt algorithm. the general concept of da is shown in figure . the pivotal behavioral characteristics of the dragonfly are (i) separation, (ii) alignment, and (iii) cohesion. the genetic property of dragonfly neurons is utilized to trace and traject the highest range of temperature from a solar panel. the trajectory path is computed as an objective function for all values of the traced parameter until the required temperature is captured and is amaximum. the energies , , of cohesion property of dragon implemented in the algorithm helps and focused to collect similar range of temperature at all points in the solar panel. energies , , x for peer review of amaximum. the cohesion property of dragon implemented in the algorithm helps and focused to collect similar range of temperature at all points in the solar panel. as the temperature of the solar system varies from time to time and pixel to pixel, the iridescence property implemented in da helps to discover and catch the highest temperature range and remove the unwanted low temperature levels. all of the above said processes takes place in da as the nature of similar flies has to be segregated. the populations of similar flies are grouped together and form as agents. each of these agents interacts with the naturally-framed system and the environment. (a) separation (b) orientation of similar range of temperature (c) cohesion (collection of various ranges of similar levels of temperature) (d) modified form of objective function towards highest range of temperature figure . general concept of the da algorithm in a pv system. the general concept of the da algorithm implemented in the solar system is shown in figure . as an initial step different ranges of irradiation is sensed and considered as a primary input as shown in figure a. the light sensitive characteristic of the dragonfly separates the different ranges of irradiation factor as shown in figure b. later similar ranges of temperature are grouped together as shown in figure c,d with the notation thigh, tlow, tmedium. the parameter x and xi represent the current position and neighboring position of the ith individual. the objective function describing the concept for the figure is given in equation ( ): iiii dv p ptcsfffff ,,,,....,, , ∂∂∂∂=∂ ( ) figure . general concept of the da algorithm in a pv system. as the temperature of the solar system varies from time to time and pixel to pixel, the iridescence property implemented in da helps to discover and catch the highest temperature range and remove the unwanted low temperature levels. all of the above said processes takes place in da as the nature of similar flies has to be segregated. the populations of similar flies are grouped together and form as agents. each of these agents interacts with the naturally-framed system and the environment. the general concept of the da algorithm implemented in the solar system is shown in figure . as an initial step different ranges of irradiation is sensed and considered as a primary input as shown in figure a. the light sensitive characteristic of the dragonfly separates the different ranges of irradiation factor as shown in figure b. later similar ranges of temperature are grouped together as shown in figure c,d with the notation thigh, tlow, tmedium. the parameter x and xi represent the current position and neighboring position of the ith individual. the objective function describing the concept for the figure is given in equation ( ): ∂ f = ∂ f , ∂ f , ∂ f , . . . ∂ f dv p , si, ci, ti, pi ( ) equation ( ) shows the different levels of the objective function as ∂ f , ∂ f , ∂ f , . . . ∂ f dv p , where ∂ f is the objective function at various stages of temperatures like t , t , t , . . . tp tp is the temperature under partial shading conditions, si represents the segregation of temperature levels like low, medium, and high, ci is the collection of similar range of irradiation factor, pi is the partial radiation constant in the incident i-th radiation and ti is the orientation of levels of temperature. before starting the iteration process, the different levels of temperature are considered as population members and its minimum energies , , of and maximum level is initialized. the population members are initialized as shown in equation ( ): ∂ f ji = ∂ f i , ∂ f i , ∂ f i , . . . ∂ f dv i ( ) where ∂ f ji is the j-th range of temperature in i-th level iteration of the da and dv is the problem verdict term. the objective function is iterated continuously at any time ti+ = ti + dt (ti is a current moment, ti+ is a next moment and dt is a time step) until the maximum temperature is tracked. the temperature is traced as a function of velocity and position that helps in maintaining synchronization and the same is responsible for sharing the information as change in temperature level. msi(tt+ ) = msi(ti) + rand ∗ ( rand − msi(tt) ) ( ) the equation ( ) depicts the modified form of da msi(ti+ ) by brownian motion and it shows the transformation that captures the actual range of temperature as population formations, and making sure that the captured values are nearly having the same number of iteration function and this is genetically related to the dragon flies and, furthermore, the analysis is extended by using rand(). the movement of the dragonfly is random. this is related to the concept of irradiance that was spread over the specified time with the normal distribution. the sudden variation in temperature of the solar panel is considered as a random variable while calculating the modified form of the da msi(ti+ ). . da-based mppt algorithm with a novel controlling variable in all the previous research analysis mppt is mainly utilized to track maximum power in the solar pv systems. among different types of mppt algorithm the mppt—p and o algorithm is the most common method used to track maximum power. however, this seems to be ineffective in tracing the maximum power under partial shading condition. to improve the power tracking in an effective way at all environmental condition this manuscript proposes the dragonfly concept in mppt. the characteristics of the dragonfly can be utilized to track the effective sun’s energy. the solar energy varies from time to time and also the temperature of the solar system varies frequently. this variation is tracked effectively by means of implementing the dragonfly characteristics. the reason for choosing this algorithm in tracking the sun is the dragonfly flies fast both forward and backward. likewise for any variation in temperature from solar energy, the dragonfly algorithm is capable of tracing the highest level of temperature by moving forward and backward. additionally, the implementation of this algorithm understands the present climatic condition and adapts itself to the present environment to self-realize and track the highest temperature to produce the highest power at its output. the abrupt change in the weather, geographical change and shadow causes sudden change in the i-v and p-v system characteristics. this sudden change in the characteristics causes system in- stability. adjusting only the pi controller gain alone will not stabilize the entire system. therefore, a new controlling variable ‘r’ is introduced as shown in equation ( ) by taking the instantaneous value of pv system voltage vpv and current ipv as a reference. r = c + c ipv − c vpv ( ) where c , c &c are constants. the selection of c , c &c causes rre f to be in the range of specified range of operation for any amount of variation in the input parameter like irradiance and temperature. the inclusion of new controlling variable rre f causes the system to maintain stability. in vi characteristics the v and i vary inversely and, hence, rmin&rmax are calculated as a function of r as given in equation ( ): f (x(r) = { c − c voc(pv), r < c + c isc(pv), r ≥ ( ) energies , , of the vi and vr characteristics’ different ranges of illumination and pv temperature are shown in figures and . after including the controlling parameter r the solar v-i characteristics are compared with the v-r characteristics. for different ranges of illumination the maximum power point is represented as a dotted line. this holds well under all ranges of illumination and even under partial shading conditions. the proposed method tracks the maximum amount of power in all conditions with the inclusion of the novel controlling term r with the minimum and maximum worst conditions in the mppt- da algorithm. the dreadful condition is obtained at an extreme point of c − c voc(pv) and a minimum of c + c isc(pv) c − c voc(pv) is the maximum at a minimum value of voc(pv) and c + c isc(pv) is the minimum at the zero value of isc(pv) as given in equation ( ). f (x(r) =   max ( c − c voc(pv) ) @vmin −oc(pv) min ( c + c isc(pv) ) , @isc(pv) = ( ) energies , , x for peer review of pvpv vciccr −+= ( ) where &, ccc are constants. the selection of &, ccc causes refr to be in the range of specified range of operation for any amount of variation in the input pa- rameter like irradiance and temperature. the inclusion of new controlling variable refr causes the system to maintain stability. in vi characteristics the v and i vary inversely and, hence, maxmin & rr are calculated as a function of r as given in equation ( ):    ≥+ <− = , ,)(( )( )( ricc rvcc rxf pvsc pvoc ( ) the vi and vr characteristics’ different ranges of illumination and pv temperature are shown in figures and . after including the controlling parameter r the solar v-i characteristics are compared with the v-r characteristics. for different ranges of illumi- nation the maximum power point is represented as a dotted line. this holds well under all ranges of illumination and even under partial shading conditions. the proposed method tracks the maximum amount of power in all conditions with the inclusion of the novel controlling term r with the minimum and maximum worst conditions in the mppt-da algorithm. the dreadful condition is obtained at an extreme point of )( pvocvcc − and a minimum of )( pvscicc + )( pvocvcc − is the maximum at a minimum value of )(pvocv and )( pvscicc + is the minimum at the zero value of )(pvsci as given in equation ( ). energies , , x for peer review of figure . v-i and v-r characteristics for different illuminations. figure . v-i and v-r characteristics for different pv temperature. figure . v-i and v-r characteristics for different illuminations. the proportional values of the constants c , c &c are generated from the schematic shown in figure . it is the simple voltage divider circuit designed to identify the new controlling variable ‘r’ as given in equation ( ). r = r r r r + r r + r r vconst − r r kvg r r + r r + r r vpv + r r kig r r + r r + r r ipv ( ) energies , , of on comparing equation ( ) with equation ( ), the constants c , c &c can be identi- fied as given in equation ( ): c = r r r r +r r +r r vconst c = r r kig r r +r r +r r c = r r kvg r r +r r +r r ( ) for different ranges of irradiance and temperature variation the value of vpv&ipv varies abruptly. this abrupt variation causes the constants in the controlling variable r to vary. in the third term in equation ( ) kig is the current gain ( iout /ipv ) . therefore, the third term in equation ( ), kig is replaced with ( iout /ipv ) and if it is substituted in the third term of equation ( ), we obtain (r r io /r r + r r + r r ). here, r io gives the units of voltage. based on this variation the population membership functions are initialized as given in equation ( ). then the objective function, as shown in equation ( ), is iterated continuously until the maximum amount of power is tracked irrespective of temperature variation, irradiance, and partial shading condition. the simulation test results showing the variation of r with an increase or decrease in the value of constants. energies , , x for peer review of figure . v-i and v-r characteristics for different illuminations. figure . v-i and v-r characteristics for different pv temperature. figure . v-i and v-r characteristics for different pv temperature. with the continuous iteration of the objective function framed by using equation ( ), the range of operation of controlling variable r is identified. within this range of operation energies , , of the complete system is simulated to trace maximum amount of power even under partial shading condition. these characteristics of dragonfly are taken into account along with the mppt algo- rithm to develop a new dragonfly mppt forward and reverse algorithm. the flowchart shown in figures and represents the implementation of the concept of dragonfly concept in mppt forward-reverse algorithm. the evaluation of da in mppt is done in matlab r to obtain the solution of single and multi-objective problems. the hunting and relocation strategies of dragon flies are implemented in pv technology to track maximum source of power. the hunting strategy is implicated for static flies and it can be flied and traced within the limited distance. energies , , x for peer review of    =+ − = − @),min( @)max()(( )()( )(min)( pvscpvsc pvocpvoc iicc vvcc rxf ( ) the proportional values of the constants &, ccc are generated from the schematic shown in figure . it is the simple voltage divider circuit designed to identify the new controlling variable ‘r’ as given in equation ( ). figure . circuit to generate the controlling variable r. pv ig pv vg const i rrrrrr krr v rrrrrr krr v rrrrrr rr r ++ + ++ − ++ = ( ) on comparing equation ( ) with equation ( ), the constants &, ccc can be identified as given in equation ( ): constv rrrrrr rr c ++ = ( ) rrrrrr krr c ig ++ = rrrrrr krr c vg ++ = for different ranges of irradiance and temperature variation the value of pvpv iv & varies abruptly. this abrupt variation causes the constants in the controlling variable r to vary. in the third term in equation ( ) kig is the current gain ( )pvout ii . therefore, the third term in equation ( ), kig is replaced with ( )pvout ii and if it is substituted in the third term of equation ( ), we obtain ( ) rrrrrrirr o ++ . here, oir gives the units of voltage. based on this variation the population membership functions are ini- tialized as given in equation ( ). then the objective function, as shown in equation ( ), is iterated continuously until the maximum amount of power is tracked irrespective of temperature variation, irradiance, and partial shading condition. the simulation test re- sults showing the variation of r with an increase or decrease in the value of constants. with the continuous iteration of the objective function framed by using equation ( ), the range of operation of controlling variable r is identified. within this range of opera- tion the complete system is simulated to trace maximum amount of power even under partial shading condition. figure . circuit to generate the controlling variable r. energies , , x for peer review of these characteristics of dragonfly are taken into account along with the mppt algo- rithm to develop a new dragonfly mppt forward and reverse algorithm. the flowchart shown in figures and represents the implementation of the concept of dragonfly concept in mppt forward-reverse algorithm. the evaluation of da in mppt is done in matlab r to obtain the solution of single and multi-objective problems. the hunting and relocation strategies of dragon flies are implemented in pv technology to track maximum source of power. the hunting strategy is implicated for static flies and it can be flied and traced within the limited distance. figure . flowchart of the dragonfly mppt forward and reverse algorithm. the flowchart shown in figure shows two division. first part comprises of drag- onfly algorithm and the second part comprises of forward and reverse algorithm to track figure . flowchart of the dragonfly mppt forward and reverse algorithm. energies , , of energies , , x for peer review of the maximum power. the parameters of v and i from solar pv system is takes as refer- ence from dragonfly algorithm part and it is fed as a reference to the tracking algorithm part. the variation in temperature causes the reference current and voltage to change, which causes the entire system to work in forward and reverse paths towards the max- imum power tracking strategy. the relocating strategy is implicated for dynamic flies and it can be traced for longer distance. the source of power has different ranges of temperature and the range of temperature at different points varies depending upon different rays spread by nature. the similar value of temperature range is grouped to- gether as agent and categorized as low-level, mid-level, and high-level temperature. the categorized levels of agent are made to interact with the other levels and surrounding environment. for each level of the temperature range an objective function is computed to update the weights. figure . flowchart of the dragonfly algorithm. . pseudo code of the dragonfly mppt-fr algorithm the proposed algorithm shown in figure , and the temperature tracing strategy using da is shown in figure . it states that the dragonfly characteristics are limited to shorter distances. within the short span of distance the different ranges of temperature are traced at a faster rate and collected as a membership functional population. the dif- ferent range of distances is shown as small geometric hexagonal shapes. a sample of space is taken as references and the temperature is measured at different positions and is simulated in matlab. the dragonfly algorithm is implemented along with mppt-forward and reverse algorithm for tracking and routing the various ranges of temperature as shown in figure . this output is shown for the sampled distance of m. figure . flowchart of the dragonfly algorithm. . pseudo code of the dragonfly mppt-fr algorithm the proposed algorithm shown in figure , and the temperature tracing strategy using da is shown in figure . it states that the dragonfly characteristics are limited to shorter distances. within the short span of distance the different ranges of temperature are traced at a faster rate and collected as a membership functional population. the different range of distances is shown as small geometric hexagonal shapes. a sample of space is taken as references and the temperature is measured at different positions and is simulated in matlab. the dragonfly algorithm is implemented along with mppt-forward and reverse algorithm for tracking and routing the various ranges of temperature as shown in figure . this output is shown for the sampled distance of m. figure . dragonfly mppt-fr algorithm. energies , , of energies , , x for peer review of figure . dragonfly mppt-fr algorithm. figure . temperature tracing strategy using da. figure . temperature tracing strategy using da. energies , , x for peer review of figure . dragonfly algorithm used for routing different ranges of temperature. after the measurement of temperature at different location, new objective function is computed for various levels of temperature gradients as shown in figure . the new objective function is computed by using an equations ( )–( ) at different iiii ptcs ,,, and the respective voltage, current, and power values are updated to the traced maxi- mum level of temperature and are shown in figure . the proposed system is tested in matlab (matlab a) with lower number of sampled agents. in the above measured data—temperature, % of the dragonflies’ data are utilized to train other samples, while % of data is utilized for testing purposes to trace the maximum power. figure . temperature gradient for different objective functions. figure . dragonfly algorithm used for routing different ranges of temperature. after the measurement of temperature at different location, new objective function is computed for various levels of temperature gradients as shown in figure . the new objective function is computed by using an equations ( )–( ) at different si, ci, ti, pi and the respective voltage, current, and power values are updated to the traced maximum level of temperature and are shown in figure . the proposed system is tested in matlab (matlab a) with lower number of sampled agents. in the above measured data— temperature, % of the dragonflies’ data are utilized to train other samples, while % of data is utilized for testing purposes to trace the maximum power. the simulated output is recorded as shown in table and its output graph is as shown in figures and . from the recorded output it is observed that the power drawn from the solar pv system is the maximum to a value of around watts at t = ◦c. for a continuous variation in temperature from solar insolation, the implemented dragonfly forward-reverse algorithm tracks the maximum amount of power. the characteristic of the dragonfly algorithm allows the designed system to trace the highest temperature with a minimum of processing time. additionally, implementation of this algorithm understands the present climatic condition and adapts itself to the present environment to self-realize and track the highest temperature to produce the highest power at its output. performance analysis of proposed algorithm in general performance analysis of proposed algorithm can be verified using two different characteristics, which include (i) convergence and (ii) robustness. the purpose energies , , of of choosing convergence characteristics is to check how fast the algorithm yields local optimum solutions. figure shows the convergence characteristics of proposed method where, solar power that is particular for projected method reaches the optimum solution within the th iteration. this is not conceivable for other existing algorithms as the amount of solar power is much higher and with such a large amount of power it is difficult to attain optimal solutions. once the convergence characteristic of proposed algorithm is suitable for implantation unit then the quality of implantation should be checked. figure shows the robustness characteristics of proposed algorithm where, the quality is greatly improved when compared to existing methods. even with smaller trial run the projected algorithm yields best quality and it is best for implementing even at larger run. energies , , x for peer review of figure . dragonfly algorithm used for routing different ranges of temperature. after the measurement of temperature at different location, new objective function is computed for various levels of temperature gradients as shown in figure . the new objective function is computed by using an equations ( )–( ) at different iiii ptcs ,,, and the respective voltage, current, and power values are updated to the traced maxi- mum level of temperature and are shown in figure . the proposed system is tested in matlab (matlab a) with lower number of sampled agents. in the above measured data—temperature, % of the dragonflies’ data are utilized to train other samples, while % of data is utilized for testing purposes to trace the maximum power. figure . temperature gradient for different objective functions. figure . temperature gradient for different objective functions. energies , , x for peer review of figure . d view of the piv characteristics of the solar pv source. the simulated output is recorded as shown in table and its output graph is as shown in figures and . from the recorded output it is observed that the power drawn from the solar pv system is the maximum to a value of around watts at t = °c. for a continuous variation in temperature from solar insolation, the implemented dragonfly forward-reverse algorithm tracks the maximum amount of power. the char- acteristic of the dragonfly algorithm allows the designed system to trace the highest temperature with a minimum of processing time. additionally, implementation of this algorithm understands the present climatic condition and adapts itself to the present en- vironment to self-realize and track the highest temperature to produce the highest power at its output. table . processing time of mppt and da—mppt. objective function iteration temperature range of the objective function processing time (sec) power drawn from solar (watts) mppt da with mppt—fr mppt da with mppt—fr °c . . . . °c . . . . °c . . . . °c . . . . °c . . . . °c . . . . °c . . . . figure . d view of the piv characteristics of the solar pv source. table . processing time of mppt and da—mppt. objective function iteration temperature range of the objective function processing time (sec) power drawn from solar (watts) mppt da with mppt—fr mppt da with mppt—fr f ◦c . . . . f ◦c . . . . f ◦c . . . . f ◦c . . . . f ◦c . . . . f ◦c . . . . f ◦c . . . . energies , , of energies , , x for peer review of figure . temperature vs. processing time of mppt and da with the mppt-fr algorithm. figure . power drawn from pv system as a function of temperature of mppt and da with mppt-fr algorithm. performance analysis of proposed algorithm in general performance analysis of proposed algorithm can be verified using two different characteristics, which include (i) convergence and (ii) robustness. the purpose of choosing convergence characteristics is to check how fast the algorithm yields local optimum solutions. figure shows the convergence characteristics of proposed method where, solar power that is particular for projected method reaches the optimum solution within the th iteration. this is not conceivable for other existing algorithms as the amount of solar power is much higher and with such a large amount of power it is difficult to attain op- timal solutions. once the convergence characteristic of proposed algorithm is suitable for implantation unit then the quality of implantation should be checked. figure shows the robustness characteristics of proposed algorithm where, the quality is greatly im- proved when compared to existing methods. even with smaller trial run the projected algorithm yields best quality and it is best for implementing even at larger run. figure . temperature vs. processing time of mppt and da with the mppt-fr algorithm. energies , , x for peer review of figure . temperature vs. processing time of mppt and da with the mppt-fr algorithm. figure . power drawn from pv system as a function of temperature of mppt and da with mppt-fr algorithm. performance analysis of proposed algorithm in general performance analysis of proposed algorithm can be verified using two different characteristics, which include (i) convergence and (ii) robustness. the purpose of choosing convergence characteristics is to check how fast the algorithm yields local optimum solutions. figure shows the convergence characteristics of proposed method where, solar power that is particular for projected method reaches the optimum solution within the th iteration. this is not conceivable for other existing algorithms as the amount of solar power is much higher and with such a large amount of power it is difficult to attain op- timal solutions. once the convergence characteristic of proposed algorithm is suitable for implantation unit then the quality of implantation should be checked. figure shows the robustness characteristics of proposed algorithm where, the quality is greatly im- proved when compared to existing methods. even with smaller trial run the projected algorithm yields best quality and it is best for implementing even at larger run. figure . power drawn from pv system as a function of temperature of mppt and da with mppt-fr algorithm. energies , , x for peer review of figure . convergence characteristics. figure . robustness characteristics. . conclusions this manuscript is proposed with novel mppt-forward and reverse flow technique with the dragonfly concept. by using this algorithm the maximum amount of energy is drawn from solar with a minimum of processing time. the multi-objective problem is focused in the analysis. the analysis is focused and simulated to trace maximum tem- figure . convergence characteristics. energies , , of energies , , x for peer review of figure . convergence characteristics. figure . robustness characteristics. . conclusions this manuscript is proposed with novel mppt-forward and reverse flow technique with the dragonfly concept. by using this algorithm the maximum amount of energy is drawn from solar with a minimum of processing time. the multi-objective problem is focused in the analysis. the analysis is focused and simulated to trace maximum tem- figure . robustness characteristics. . conclusions this manuscript is proposed with novel mppt-forward and reverse flow technique with the dragonfly concept. by using this algorithm the maximum amount of energy is drawn from solar with a minimum of processing time. the multi-objective problem is focused in the analysis. the analysis is focused and simulated to trace maximum temperature with less processing time. randomization based on si played an important role in exploration and exploitation. the randomization of da in mppt-forward and reverse flow is effectively utilized in pv source to track maximum power. the different objective function f , f , f , . . . f is calculated using equation ( ). the objective function calculated the temperature as membership population and for each range of temperature level, processing time, and power tracking from solar pv system is tabulated. the proposed algorithm is tested solar pv system to track maximum power. the tracking time of da based mppt-fr algorithm is less than conventional mppt technique as tabulated in table . additionally, the power drawn using the da-based mppt-fr algorithm is more than a conventional tracking system. the implementation of a new controlling variable r makes the complete pv system track the maximum amount of power even under partial shading conditions. additionally, the use of da-based mppt has the sharp edges in tracking the maximum power at all times during the day as it is based on memory-based techniques. with the implementation of da based mppt-fr algorithm the tracking power is maximum at all times with less tracking and processing time. author contributions: conceptualization: s.u., f.a., h.m., y.t., and r.k.; methodology: s.u., h.m., y.t., and r.k.; software: s.u., f.a., h.m., y.t., and r.k.; validation: s.u., f.a., h.m., y.t., and r.k.; formal analysis: s.u., h.m., y.t., and r.k.; investigation: s.u., h.m., y.t., and r.k.; resources: s.u., h.m., y.t., and r.k.; data curation: s.u., f.a., h.m., y.t., and r.k.; writing—original draft preparation: s.u., h.m., y.t., and r.k.; writing—review and editing, s.u., h.m., y.t., and r.k.; visualization: s.u., f.a., h.m., y.t., and r.k.; supervision: s.u., f.a., h.m., y.t., and r.k.; project administration: s.u.; funding acquisition: h.m., f.a. all authors have read and agreed to the published version of the manuscript. energies , , of funding: the apc was funded by the princess nourah bint abdulrahman university, riyadh, saudi arabia, through the fast-track research funding program. acknowledgments: this research was funded by the deanship of scientific research at princess nourah bint abdulrahman university through the fast-track research funding program. conflicts of interest: the authors declare no conflict of interest. references . yang, x.-s.; he, x. swarm intelligence and evolutionary computation: overview and analysis, in studies in computational intelligence; springer: cham, switzerland, ; pp. – . . kothari, v.; anuradha, j.; shah, s.; mittal, p. a survey on particle swarm optimization in feature selection, in communications in computer and information science; springer: berlin, germany, ; pp. – . . kennedy, j.; eberhart, r. particle swarm optimization. in proceedings of the icnn’ nternational conference on neural networks, perth, wa, australia, november– december ; volume , pp. – . 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[crossref] http://doi.org/ . /icnn. . http://doi.org/ . /cec. . .c http://doi.org/ . /s - - - http://doi.org/ . /tste. . http://doi.org/ . /icmic. . http://doi.org/ . /tie. . http://doi.org/ . /tie. . http://doi.org/ . / / http://doi.org/ . /tevc. . http://doi.org/ . / / http://www.ncbi.nlm.nih.gov/pubmed/ http://doi.org/ . / / http://www.ncbi.nlm.nih.gov/pubmed/ http://doi.org/ . /j.jcp. . . http://doi.org/ . /nature http://www.ncbi.nlm.nih.gov/pubmed/ http://doi.org/ . /s - - - 	introduction 	dragonfly algorithm in pv system 	da-based mppt algorithm with a novel controlling variable 	pseudo code of the dragonfly mppt-fr algorithm 	conclusions 	references paper .dvi munich personal repec archive oil crisis, energy-saving technological change and the stock market crash of - alpanda, sami and peralta-alva, adrian amherst college, university of miami august online at https://mpra.ub.uni-muenchen.de/ / mpra paper no. , posted nov : utc oil crisis, energy-saving technological change and the stock market crash of - ∗ sami alpanda department of economics amherst college adrian peralta-alva department of economics university of miami august, . abstract the market value of u.s. corporations was nearly halved following the oil crisis of october . real energy prices more than doubled by the end of the decade, increasing energy costs and spurring innovation in energy-saving technologies by corporations. this paper uses a neo-classical growth model to quantify the impact of the increase in energy prices on the market value of u.s. corporations. in the model, corporations adopt energy-saving technologies as a response to the energy price shock and the price of installed capital falls due to investment irreversibility. the model calibrated to match the subsequent decline in energy consumption in the u.s. generates a % decline in market valuation - accounting for nearly half of what is observed in the data. introduction the market value of u.s. corporations, relative to the replacement cost of their tangible assets, was nearly halved during - (see figure ). this ratio, also known as the tobin’s (average) q, was around . over the - period, fell sharply during - , and stagnated for the following decade. over - , tobin’s q for u.s. corporations averaged only . , % less relative to the decade prior to . tobin’s q did not recover until the late s. ∗we thank michele boldrin, ellen mcgrattan, edward c. prescott and manuel santos for their continuous support and advice. we have also benefited from discussions with luca bossi, v.v. chari, pere gomis-porqueras, larry jones, david kelly, walter nicholson, salvador ortigueira, steven rivkin, geoffrey woglom and beth yarborough. all remaining errors are ours. adrian peralta-alva acknowledges the support of the james w. mclamore summer award in business and social sciences at the university of miami. see the data appendix for data sources and calculations underlying all figures. . . . . . . . . . . figure : tobin’s average q: market value relative to replacement value of tangible assets of u.s. corporations this abrupt decline in corporate market valuations coincides exactly with the oil crisis initiated by the opec embargo announced in early october of . the largest drop in market values occurred in the th quarter of and throughout (see figure ). . . . . . . . . . . . e n d o f q figure : market value of u.s. corporations relative to gdp the oil crisis translated into a % percent increase in real energy prices over - . energy prices continued to rise for the rest of the decade, especially during - due to the events in iran (see figure ). by , real energy prices were . times higher than what they were in . energy prices declined after ; however, they had yet to come back to their pre- levels after years. . . . . . . . . . . energy price deflator / gdp deflator figure : energy prices relative to gdp deflator ( = ) the main objective of this paper is to determine how much of the decline in the market value of non-energy producing corporations can be accounted for by the observed changes in energy prices. to do so, we employ a dynamic general equilibrium model with technology-specific capital and investment irreversibility. these assumptions are standard in the literature (cf. sargent [ ], dixit and pyndick [ ]), and allow for tobin’s q to fall below as in the data. in the model economy firms develop and adopt energy-saving technologies as a response to the energy price shock and the price of installed capital falls due to investment irreversibility. firms do not introduce these energy-saving technologies prior to the energy shock because it is costly for them to do so. the two costs involved in the process of developing and adopting a new type of capital are, first, a minimum size investment requirement similar to boldrin and levine [ ] and, second, a learning curve associated with the use of the new technology. with low energy prices, firms forego these costs. with sharp increases in energy prices, however, it pays for corporations to incur them. we calibrate the parameters of the model to match certain features of the u.s. economy; in particular we set the energy-efficiency of the new technologies to match the decline in real energy-output ratios. our model suggests energy prices can account for almost half of the drop in tobin’s q, and partially for its stagnation throughout the s and s. the links between the increase in energy prices and the fall in the market value of non-energy producing corporations, which are the focus of our analysis, are straightforward: first, the sharp and persistent increase in energy costs squeezed both current and expected future dividends causing a fall in market value. second, as the increase in energy costs was highly persistent, corporations started adopting and investing in new technologies that were more energy-efficient. this spur in energy-saving technologies resulted in capital obsolescence for the old energy-inefficient technologies bahk and gort [ ] gives empirical support to the existence of learning by doing in the context of a production function similar to the one in our model. the inclusion of learning by doing in aggregate quantitative studies like ours is common place in the literature. recent contributions include klenow [ ] in the area of productivity analysis, young [ ] and parente [ ] in development, and chang, et. al. [ ] in business cycles. driving their value down (cf. baily [ ]). although these links are intuitive and the timing of the two events is suggestive, the energy explanation has had difficulties both empirically and theoretically and has led many authors to entertain other explanations for the stock market crash of - . there are mainly two empirical criticisms regarding the energy explanation. the first is that there is not a high enough correlation between the drop in market values and the pre- cost share of energy for corporations (cf. wei [ ], and greenwood and jovanovic [ ]). we have computed the correlation between the percentage decline in market value from to and the ratio of energy expenditure to value added for all manufacturing industries (non-energy producing) at the -digit sic code and found that this coefficient is actually negative. thus, we confirm previous results that energy-intensive industries did not suffer the largest drops in market value. the second empirical criticism is the absence of a stock market crash during the energy price shocks of - . on the theoretical side, it has been difficult to construct models where energy prices have a quantitatively significant impact on corporate market values primarily because the share of energy in total costs is small. in particular, wei [ ] uses a putty-clay model that encompasses endogenous obsolescence of capital to find that energy price increases can account for only % of the decline in market valuation. the aforementioned empirical criticisms would be especially strong if rising energy costs were the only channel through which energy affected market values and tobin’s q. however, this is not necessarily the case. in fact, there is no reason to expect a drop in tobin’s q due to an increase in energy prices as long as the price of installed capital does not deviate from potential replacements. in section , we show that as long as investment in the old technologies does not stop, tobin’s q will remain constant regardless of the cost share of energy. in this respect, the introduction of new energy-efficient technologies and the obsolescence of old technologies appears to be a better explanation for the drop in tobin’s q. the latter transmission mechanism has the implication that the drop in tobin’s q should be correlated with the drop in the energy consumption to corporate gdp ratio (rather than the pre-crisis level of energy cost share). this implication of our model is largely supported by the data as the industries that suffered larger drops in market value also experienced large declines in their cost share of energy. using energy expenditure data (at the - digit sic level) from the annual survey of manufactures, together with market value trends by sic from standard and poor’s compustat, we found that the correlation between the drop in energy cost share between and and the percent decline in market values in - is . . another implication of the transmission mechanism we propose is that further price shocks would not necessarily impact tobin’s q, as long as newly introduced capital after the initial price shock does not become obsolete after further price shocks; as for instance the absence of a fall in market market value by sic is taken from the standard and poor’s compustat quarterly data base. we only consider the market value of firms listed in compustat before , which controls for the effects of entry. energy expenditure and value added by sic is taken from the annual survey of manufactures. we only considered manufacturing industries as comprehensive data on energy expenditure at -digit sic do not exist for all sectors. notice also that we used energy expenditure as a proxy for energy consumption given that no data on energy consumption at -digit sic sector is available for our sample period. value during - . on the theoretical side, the putty-clay model can deliver only a small decline in market values as a result of the energy crisis. the energy crisis translates, through a general equilibrium effect, into a decline of wages that almost completely counteracts the negative impact on dividends of higher energy costs. thus, in a putty-clay framework the energy crisis translates into a small decline in the present value of dividends (cf. wei [ ]). the drop in the wage rate required for the labor market to clear after the energy shock is relatively smaller in our model because labor can be freely adjusted in both the new and the old technology unlike the putty-clay model where the only adjustment takes place for the new technologies. this is translated into a bigger drop in market values in our model relative to the putty-clay model. moreover, the standard putty-clay model delivers predictions for energy consumption that are not consistent with the u.s. data. in particular, under perfect foresight for energy prices, a putty-clay model would predict an increasing real energy to value added ratio during the s and s, a period where energy prices substantially declined. this prediction is at odds with what is observed in the data. as figure below illustrates, real energy use (as a share of business gdp) declined monotonically after - . the monotone decline in energy is, however, consistent with the introduction of a new technology characterized by a lower energy requirement per unit of production (i.e. energy-saving technological change), which is one of the main features of our model. % % % % % % % % nominal real figure : energy expenditure (nominal) and energy use (real) of the business sector as a share of business gdp our paper focuses on the - period which hall [ ] refers to as the “single hardest [equity market] episode to understand”; a period where the market value of u.s. corporations was much lower than the replacement cost of their tangible assets. other explanations put forward for the stock market crash of - are the it revolution (cf. greenwood & jovanovic [ ], and a more detailed discussion of these issues are provided in sections and . we do not try to account for the boom and subsequent crash in equity prices during - . laitner and stolyarov [ ]) and investment subsidies provided by the government to businesses in this period (cf. mcgrattan & prescott [ ]). the it explanation is similar to ours in spirit, whereby the innovation of information technologies drives down the price of installed capital. peralta-alva [ ] uses a neoclassical growth model with capital accumulation to test this idea and finds that the quality of new technologies that will generate the observed drop in tobin’s q would also generate a two-fold increase in investment, sharply in contrast with the data. mcgrattan & prescott [ ] argue that the investment subsidies drive a wedge between the price of installed capital and replacement capital and can account for one third of the decline in market valuations observed in the s. our model is not inconsistent with this explanation, since investment subsidies were given partly to encourage firms to adopt energy-efficient technologies. we, nevertheless, abstract from subsidies in our model, and study the effects of the oil crisis and energy-saving technological change in isolation from the government response. the rest of our paper is structured as follows: section provides some empirical evidence in support of the price induced innovation hypothesis. section lays out the model. calibration of model parameters are given in section and findings are discussed in section . section concludes. energy-saving technological change after our model connects the decline in the energy requirements per unit of output observed in the u.s. aggregate data to the endogenous introduction of energy-saving technologies. a fundamental as- sumption in our analysis is that capital embodies a particular technology as in solow [ ]. our hypothesis is that the observed increase in energy prices provided the right incentives for firms to develop and adopt a new type of capital. the introduction of this new type of capital, in turn, resulted in a new aggregate production function characterized by its energy-saving properties. in what follows, we elaborate on the existing empirical support for our key hypotheses and assumptions. first, we evaluate the main alternative explanation for the observed decline in the u.s. aggregate energy consumed per unit of output, which attributes this decline to changes in the sectoral com- position of the u.s. gdp. we find that this alternative explanation falls short of accounting for the data. secondly, we give some key examples of energy-saving technologies introduced during the mid- s as a result of the energy crisis of - . the observed decline in the energy to gdp ratio might have been caused by changes in the level and structure of sectoral activity. as it is well known, the sectoral composition of the u.s. gdp has changed quite dramatically over the last years. in particular, the value added of the manufacturing sector (which is energy intensive) has declined relative to gdp. at the same time, the value added of service sectors, which are less energy intensive, have increased relative to gdp. to test whether changes in sectoral composition can account for the observed decline in the energy to gdp ratio, we performed the following experiment: first, we obtain from jorgenson’s klem data set the average - real energy to value added ratio for each economic sector at the digit sic classification level. then we compute, from the sectoral gdp-by-industry accounts of the bea, the change in the fraction of the gdp produced by each of these sectors. finally, we assume that the energy to value added ratio of all sectors remained constant across time and compute the implied energy output ratio at the aggregate level. we find that sectoral activity can account for less than a fifth of the total decline of the energy output ratio (a drop of % in the overall energy to output ratio). this result is consistent with the findings of schiper [ ] and with those of the international energy agency [ ], which document that most of the decline in energy intensity of the u.s. economy can be attributed to improved energy efficiency and not to the change in sectoral composition. examples for the introduction of energy-saving technologies during the mid- ’s abound. one of the most important changes in the manufacturing sector during the - period was the in- creased use of advanced manufacturing technologies (amts). amts include computer aided design and manufacturing, numerically-controlled machines, and information networks. these improve- ments constitute a form of embodied technological change. doms and dunne [ ] use establishment- level data to determine changes in energy intensity arising from differences in plant characteristics and energy prices. the first of their two main findings is that plants that utilize higher numbers of amts are less energy intensive. their second finding is that plants constructed during the period of high energy prices, - , are generally more energy efficient than plants built during other periods. another development that lowered the energy intensity of all sectors was the introduction of energy-efficient buildings. u.s. residential and commercial buildings consume % of all u.s. energy and are therefore key to understand the trends in energy intensity. rosenfeld [ ] finds that most of the efficiency gains in the heating and cooling of buildings took place during the period of - . during those years, technological improvements in the heating, lighting and cooling systems allowed for a decrease of . million barrels of oil consumption per day despite the fact that million new homes were built, and commercial floor space increased by percent. another sector that experienced dramatic energy-saving changes after was the plastics industry. joyce [ ] documents that the union carbide unipol process, introduced in the mid- s, required a much smaller plant, produced twice as much product, and lowered the energy efficiency of polyethylene production from btus per pound to btus. other authors have suggested a causal link between the energy crisis and the introduction of energy-saving technologies. for example, schurr [ ] finds that the energy intensity of the u.s. economy started its long-run decline by the end of world war i and stabilized (actually increased slightly) during - . he finds that energy intensity declined at a faster speed between - than any other period in the th century. he concludes that the introduction of energy-saving technologies resulting from the oil crisis is the main culprit for this faster decline. popp [ ] uses patent data to analyze the impact of energy prices on energy-saving innovation. he finds that the the klem data set is available online at http://post.economics.harvard.edu/faculty/jorgenson/data/ klem.html. many more examples of energy-saving technologies introduced during the mid s can be found in tester, wood and ferrari [ ]. number of successful patent applications of energy-saving technologies increased dramatically during the mid- s. the main conclusion of the author, based on econometric analysis, is that energy prices have a strong, positive impact on the number of energy-saving technologies. model economy in this section, we present a general equilibrium asset pricing model with capital accumulation and an explicit causal link between energy prices and the introduction of energy-saving technologies. production is undertaken by corporations which are in turn owned by infinitely-lived households. energy, an input in production, is imported from abroad and there is trade balance each period. there are two types of production technologies which differ in their energy requirements. capital is technology specific and investment decisions are irreversible. prior to , agents assume that energy prices are going to stay at their pre-crisis level forever. the energy crisis takes place in the beginning of and takes the agents in the model by surprise. after , the model is deterministic and all economic agents have perfect foresight on energy prices. in particular, agents learn after about the actual sequence of energy prices, as reported in figure . available evidence (see section . ) suggests energy price expectations during the mid s pointed towards continuously high (and possibly increasing) energy prices in both the short-run and the long-run. hence, our analysis derives a lower bound for the magnitude of the drop in market value that can be explained by the energy crisis. stand-in household the population in period t is denoted by nt and it grows with factor η, so nt+ = ηnt. the stand-in household’s preferences are described by the following utility function ∞x t= βtu(ct)nt, where c is per-capita consumption, and u(·) is given by u(c) = ( c −σ −σ for σ > , σ = log(c) for σ = which implies an intertemporal elasticity of substitution equal to /σ. each member of the household is endowed with a unit of time each period, which is supplied inelastically to the labor market. the household participates in a market for shares of the corporations. owning a fraction st of the perfectly divisible share entitles the shareholder to the same fraction of the dividends paid by the firm. the household’s problem is to choose sequences of consumption {ct} and shares of equity {st} that maximize utility subject to the following budget constraint: ∞x t= pt [ntct + vt (st+ −st)] = ∞x t= pt [wtnt + dtst] where v denotes the price of an equity share (after dividend payments from period t have occurred), w is the wage rate, and d is dividends per share. the arrow-debreu price, denoted by pt, is the date- value of one unit of consumption in period t. representative firm the representative firm produces the output good y, using a constant returns to scale technology. production utilizes two technology-specific types of capital, k and k , labor, n and n , energy, e and e , and is summarized by: y = y + y y = [γk ρ +( −γ)(ξ e ) ρ ] α ρ (a n ) −α y = [γk ρ +( −γ)(ξ e ) ρ ] α ρ (a n ) −α . all other factors held equal, technology one requires more energy per unit of output than technology two and thus ξ < ξ . the parameter ρ < determines the degree of complementarity between capital and energy. the labor share of total income is given by −α. the sequences of total factor productivities, a and a are exogenously given and deterministic. every period a grows by a factor of γa . as initial conditions for our analysis, we assume k , > and k , = . thus, the energy-intensive technology is active and the associated capital stock follows the law of motion k ,t+ = x ,t +( −δ)k ,t x ,t ≥ , for all t ≥ . ( ) the firm may also choose to pay the development and adoption costs of a new, energy-saving, type of capital, k . however, a one-shot minimum investment of c > units of output must be spent in order to obtain the first ψc units of k , where ≤ ψ ≤ . dt denotes the amount of resources the firm chooses to spend on the adoption and development of the energy-saving technology, and t̂ is the period when the firm chooses to incur such costs. adoption costs must be paid only once and thus dt = for all t > t̂. clearly, when ψ < , the firm would set dt̂ = c. these assumptions are standard in the literature that studies endogenous innovation in perfectly competitive settings like ours. detailed analysis on existence, uniqueness and general properties of equilibria for this type of models can be found in a series of papers by boldrin and levine [ ], [ ] and [ ]. these authors also provide a careful discussion on the economic incentives and mechanisms that make innovation possible in a world with perfect competition. after the minimum size requirement for capital of type two is satisfied for the first time, its law the behavior of a will be described below. of accumulation is standard and is given by k ,t+ = x ,t +( −δ)k ,t x ,t ≥ for all t > t̂. ( ) the level of productivity for technology is initially lower than technology one and is subject to a learning curve described by a ,t = (Λ− ( −Φ)λ−(t−t̂))a ,t for all ≤ t− t̂ ≤ , a ,t = a ,t for all t− t̂ ≥ Λ > , ≤Φ≤ , and λ > . where the parameters on the learning curve determine how much lower the initial level of a is relative to a and how fast it catches up to the level of a . the firm hires labor services and imports energy from abroad. it owns the capital stock and in turn pays dividends d to its shareholders, who are the residual claimants of the income of the firm. the output of the firm is subject to a time invariant tax at a rate of τy. dividends equal firm after-tax income less payments for wages, energy purchased at an exogenously given price pe, and new investments, i.e. d = ( −τy)y −d − x i= {wni + xi + p eei} . the objective of the firm is to maximize shareholder’s value, ∞x t= ptdt taking prices as given. competitive equilibrium a competitive equilibrium for this economy is a sequence of prices {pet,pt, vt, wt} and allocations for consumption, asset holdings, investment, energy, labor, and development costs {ct,st, x ,t, x ,t, e ,t, e ,t, n ,t, n ,t, dt} such that . given prices, {ct, st} are a solution to the household’s problem . given prices, {x ,t, x ,t,e ,t, e ,t,n ,t,n ,t,dt} are a solution to the problem of the firm the tax on output is used to match the appropriate interest rate in the calibration presented in section and is kept constant throughout our analysis. all tax revenue is assumed to be wasted by the government. . markets clear, and aggregate feasibility is satisfied at all times, namely for all t: st = n ,t + n ,t = nt ntct + x ,t + x ,t + p e t (e ,t + e ,t)+ dt = ( −τy)yt ( ) . analysis of the model first note that in any equilibrium, the replacement cost of a unit of existing capital is equal to one unit of period t consumption good. this follows as a consequence of the aggregate resource constraint ( ), and of the laws of motion of capital. the model’s replacement cost of existing capital at the beginning of period t + is then given by k ,t+ + k ,t+ , which constitutes the denominator of tobin’s q. market capitalization in the model as of the end of period t equals vt, which is the numerator of tobin’s q. therefore the model’s measure of tobin’s average q is given by qt = vt k ,t+ + k ,t+ . the equilibrium behavior of asset prices for the model economy is characterized by the following proposition : proposition in any equilibrium vt = pt ∞x τ=t+ pτdτ. ( ) moreover, in any equilibrium where the two types of capital are available vt = µ − µ ,t pt ¶ k ,t+ + µ − µ ,t pt ¶ k ,t+ , ( ) where µ and µ are the multipliers on the irreversibility constraints ( ) and ( ). proof. the consumer’s first order conditions with respect to st+ and ct imply ptvt = pt+ (dt+ + vt+ ) . ( ) development costs do not appear in asset pricing equation ( ) because of the unexpected nature of the energy price shock we consider. in general, the value of the firm equals the value of its capital, plus a term including the discounted present value of adoption costs. however, we depart from a case where agents expect energy prices to continue at their s level and no firm finds it optimal to adopt the new technology. moreover, we measure market value as the present value of future dividends. when energy prices increase unexpectedly adoption costs are immediately paid and current, but not future, dividends are affected. thus, the relevant asset pricing equation for our quantitative analysis is indeed ( ). without loss of generality set p = . the recursive application of equation ( ) delivers ptvt = limt→∞ npt τ=t+ pτdτ + pt vt o , which paired with the transversality condition limt→∞ pt vt = delivers the first result, vt = pt p∞ τ=t+ pτdτ. to derive the second part of the proposition, consider an equilibrium where capital of type two has been already introduced. the first order conditions with respect to capital and investment imply pt −µi,t = pt+ · ( −δ)+( −τy) ∂yi,t+ ∂ki,t+ ¸ −µi,t+ ( −δ), for i = , . ( ) multiply both sides of equation ( ) by ki,t+ . adding the two sides of these equalities yields ¡ pt −µ ,t ¢ k ,t+ + ¡ pt −µ ,t ¢ k ,t+ = { ¡ pt+ −µ ,t+ ¢ k ,t+ + ¡ pt+ −µ ,t+ ¢ k ,t+ }( −δ)+ +pt+ ( −τy) µ ∂y ,t+ ∂k ,t+ k ,t+ + ∂y ,t+ ∂k ,t+ k ,t+ ¶ . using the fact that competitive prices equal marginal products, the homogeneity of the production function, and the definition of dividends, we get dt+ = ( −τy) µ ∂y ,t+ ∂k ,t+ k ,t+ + ∂y ,t+ ∂k ,t+ k ,t+ ¶ −x ,t+ −x ,t+ . ( ) solve for ( −τy) ³ ∂y ,t+ ∂k ,t+ k ,t+ + ∂y ,t+ ∂k ,t+ k ,t+ ´ in ( ) and substitute the resulting term in ( ). fi- nally, the law of motion for capital can be used to obtain ¡ pt −µ ,t ¢ k ,t+ +(pt −µ ,t)k ,t+ = (pt+ −µ ,t+ )k ,t+ + ( ) (pt+ −µ ,t+ )k ,t+ + pt+ dt+ . the recursive application of equation ( ) together with the firm’s transversality conditions for capital accumulation deliver the desired result since vt = pt ∞x τ=t+ pτdτ = k ,t+ µ − µ ,t pt ¶ + k ,t+ µ − µ ,t pt ¶ note that the model delivers the standard result where the market value of the firm is equal to the expected present value of its dividend flows. the above proposition also illustrates the mechanism through which the market value of a firm can go below the replacement cost of its assets. in a world where investment decisions are reversible, if agents have too much capital, they can consume a portion of it and bring capital back to its optimal level. in a world where investment is irreversible, it is impossible to resort to this mechanism. when agents have a stock of capital larger than the optimal one, irreversibility binds and the price of capital falls below one. if there was no structural break in the behavior of energy prices of this economy, no over ac- cumulation of any given type of capital would occur and irreversibility would never bind, forcing tobin’s q to equal one at all periods. hence, the role that a sudden, unexpected, change in the behavior of energy prices plays with respect to market value is that it may imply a sudden change in the optimal composition of capital, causing the irreversibility constraint to bind. finally, observe that value of the irreversibility constraint multiplier is directly related to the magnitude of the drop in the market value of capital. thus, the larger is the benefit of switching to a new technology, the larger will be the drop in the value of existing capital. before deriving the quantitative implications of this model, it is useful to compare the trans- mission mechanism we are proposing to that in the standard putty clay model. the market value of existing capital is equal to the present discounted value of the dividend flows it generates. this fundamental asset pricing principle is valid for both the putty-clay model and ours. higher energy prices translate into higher energy costs and lower dividends. the energy crisis also has general equilibrium implications for the interest rate and wages. the increase in energy prices makes en- ergy saving technologies attractive, pushing the investment demand up. in equilibrium, increased investment demand translates into higher interest rates, which ultimately depress asset prices. our quantitative analysis below illustrates, nevertheless, that the interest rate channel is not the main reason why tobin’s q goes down more in our model than in the standard putty-clay framework after the structural break in energy prices. there are, however, important differences on the general equilibrium implications for wages between the putty-clay model and ours. some putty clay models assume the capital labor ratio must be constant for all installed capital. this ex-post fixity in the labor market requires a strong decline in real wages for the labor market to clear after the energy crisis. as wei ([ ]) illustrates, this decline in wages may almost completely counteract the drop in market value that results from increased energy costs. the drop in the wage rate required for the labor market to clear after the energy shock is relatively smaller in our model because labor can be freely adjusted in both, the new and the old technology. labor in our model is distributed across the two technologies until marginal productivities are equated. hence, the endogenous introduction of energy saving technologies counteracts the negative impact of energy prices on labor productivity and the wage rate. calibration to calibrate the parameters of the model, we follow cooley and prescott [ ] and match certain aggregate features of the u.s. economy in the pre-crisis period of - to the balanced growth path of the model. we set η equal to . to match the % average growth rate of population, and γa , the growth factor of labor-augmenting efficiency for technology , equal to . to match the average per capita growth rate of u.s. corporate gdp which is %. notice also that constant returns to scale, a ,t = a ,t, and ξ < ξ , imply that the firm will never invest a positive amount of resources in both types of technologies at the same time. estimates of the intertemporal elasticity of substitution found in the literature imply values for σ within the interval [ , ]. we pick σ = . and perform sensitivity analysis on this parameter. the depreciation rate δ is set equal to . % and the proportional tax on output, τ, to % to match the investment-corporate gdp and the capital-corporate gdp ratios of non-energy producing corporations ( . and . , respectively). we set the discount factor β to . to match a steady state real interest rate of . %. the observed average labor share of income in the corporate sector is matched by the model by setting α equal to . . γ is calibrated to . so that the model’s initial steady-state energy- corporate gdp ratio (prior to the energy shock) matches the - u.s. average ( . %). ξ is set equal to . to match the pre-crisis capital-energy ratio and ξ is set equal to so as to match a new steady-state energy-corporate gdp ratio of . %. ρ is set equal to − to match the model’s transition of energy-use to corporate gdp ratio from the old to the new steady-state as close to the data as possible. parameters c and ψ are jointly determined. we set the minimum investment size parameter c equal to . ( % of the capital stock), which is the minimum value such that corporations do not adopt the energy-saving capital before but choose to adopt after the energy shock. the percentage of the initial minimum size which is actually in operation, ψ, is set to % so that the model’s equilibrium investment matches the data one year after the shock. bahk and gort [ ] document that the higher growth in the productivity of a new technology fades away, on average, after the fifth year it was introduced. jovanovic and nyarko [ ] document "progress ratios", i.e. ratios of peak to initial productivity, from a dozen of empirical studies of learning by doing. the range is . - . . we pick a value of for our benchmark experiments and perform several sensitivity tests to the values of this parameter. all of the aforementioned empirical studies coincide in that most of the learning takes place within the first two years that follow the introduction of any given new technology. thus, we assume that one half of the total productivity gains associated with learning by doing are achieved by the second year of the introduction of the energy-saving capital. based on these observations, we set the parameters of the learning curve (Λ = . , ,Φ = . and λ = . ) such that: i) a ,t̂ = a ,t̂ ii) a ,t̂+ = a ,t+ and iii)a ,t̂+ = a ,t̂+ . results in this section, we derive the quantitative implications of the oil crisis for equity prices and other macroeconomic aggregates. in all of our quantitative experiments, we assume that the u.s. economy was in a balanced growth path equilibrium (i.e. a competitive equilibrium where all variables grow note that having only one type of adoption cost does not yield satisfactory aggregate series. for example, with only learning by doing, but no minimum size requirement, firms would invest a very small amount of technology and then wait for years for the level of productivity to catch up. with only minimum size, but no learning-by-doing, the mimimum size required for endogenous adoption is very high and therefore the aggregate series (for example investment) are unrealistic. at a constant rate) during - . households and firms assume that technological constraints and energy prices will remain unchanged over the infinite future. our analysis starts with simple versions of our model where we can illustrate clearly the role of the different channels linking energy prices to market valuations implicit in the theory. finally, we present the full-fledged version of the model where the introduction of energy-saving technologies results as an optimal choice after the energy price goes up, and where new technologies face a standard learning by doing curve. consider a version of the model where energy saving technologies arrive exogenously, for free, and paired with the energy price shock. in particular, we start off from a balanced growth path equilibrium where c equals infinity and agents expect energy prices to remain at their average - level. on , we change energy price expectations to match the time series data from up to . on , energy-saving capital becomes available, and c is set equal to zero. the results for this economy where the new technology arrives exogenously and is as productive as the old one are summarized by figure below. . . . . . . . . tobin's q (model) tobin's q (data) . . . . . . . energy/gdp (model) energy/gdp (data) . . . . . . . . . . . investment/output (model) investment/output (data) - % - % - % % % % % % gdp (model, %change) gdp (data, %change) figure : unexpected arrival of energy-saving technologies the exogenous arrival of energy-saving technologies can account for a % drop in tobin’s q. energy- saving capital enters gradually into the economy and market values recover in a smooth fashion. the computational appendix describes the numerical method employed to solve for equilibrium. the recovery takes almost years, which is consistent with the u.s. data. the model has been calibrated so that its energy to corporate gdp ratio delivers the best fit possible to the average trends of its u.s. counterpart. in this benchmark case, the energy crisis translates into an economic recession much less pronounced than what is observed in the u.s. data. notice, however, that we have abstracted from business cycle movements in total factor productivity. to understand what drives the large drop in market valuation generated by our theory, relative to previous analyses, observe that, given the high complementarity of capital and energy, higher energy prices result in higher energy costs and lower dividends. according to u.s. corporate data, corporate gdp before the energy crisis was distributed in the following way: energy costs represented . % of corporate gdp, labor costs %, investment %, taxes %, and the residual . % of corporate gdp corresponded to shareholders income. if the firm had not changed its productive inputs nor its investment level after the % average increase in energy prices observed in the data, then shareholders income would have declined to . % of corporate gdp. equity prices would then have suffered a permanent decline of % (equal to the drop in the fraction of income that accrues to shareholders). of course, firms in our model do change productive inputs and investment plans optimally after the energy shock. moreover, firm and household reactions have general equilibrium implications on interest rates and wage rates that interact with dividend flows, and thus market valuations. a counterfactual experiment that illustrates the aforementioned mechanisms consists of simulating an economy where the only available technology is energy-intensive (capital of type one) and energy prices change as in the data. the resulting equilibrium behavior of some key variables of such a model is reported in figure below. . . . . . . . e n e rg y c o s ts , in v e s tm e n t . . . . . . . w a g e r a te energy costs investment wage rate figure : distribution of value added after the energy crisis, no energy saving technology available. note that in the model economy the investment output ratio falls in contrast with the u.s. data. the increase in investment observed in the data is most likely due to investment subsidies (the investment tax credit) that peaked during the late s. our paper focuses on the impact of technical change on the stock market and abstracts from investment subsidies. nevertheless, if investment subsidies were introduced, the drop in market values predicted by our model would be even larger (cf. mcgrattan and prescott [ ]). proposition implies that the energy crisis under the aforementioned conditions generates no drop in tobin’s average q as investment remains strictly positive through the whole sample period. we also find that equity prices are not significantly affected by the energy crisis. the reason for this puzzling asset price behavior resides on the general equilibrium implications of the energy crisis. observe that energy costs double after the crisis but investments and the wage rate also suffer substantial declines. the resulting general equilibrium movements of wages and investment are just enough to compensate for the increase in energy costs and market values are not affected by higher energy prices. these results are similar in spirit to those found in wei [ ]. in contrast to the previous trends, we report in figure the behavior of energy costs, investment and the wage rate for our first benchmark experiment where energy saving technologies become available at the same time that the energy price shock hits. . . . . . . . e n e rg y c o s ts , in v e s tm e n t . . . . . . . w a g e r a te energy costs investment wage rate figure : distribution of value added from old technology, exogenous arrival of new technology observe first that irreversibility binds and, according to proposition , that must imply a drop in tobin’s average q. in sharp contrast to the case where no energy saving technology is ever available, wages move down only slightly after the second energy price shock but remain high through the whole sample period. the wage bill captures the largest fraction of corporate gdp. thus, the higher equilibrium wages generated by our model do not compensate for the increase in energy costs associated to the energy crisis. finally, figure below illustrates the equilibrium behavior of dividend flows (relative to trend) from the energy intensive technology under the two different scenarios we have considered. regarding wage behavior, the u.s. data shows a slowdown in wage growth right around . as our analysis focus on long-run analysis, our model has abstracted from cyclical movements in total factor productivity. notice, however, that the observed decline in real wages of the u.s. data could easily be rationalized by a model that incorporates an exogenous slowdown in total factor productivity compatible with what was observed for the u.s. economy. . . . . . . . . . . . dividends from old capital dividends from old capital, no new technology figure : time series behavior of dividend flows relative to a % trend. these time series reveal an important transmission mechanism embedded in our theory. observe that, before the energy crisis, existing capital was priced under the assumption that it would generate an infinite streamofdividends. however, if energysaving technologiesarriveat the timeof theenergy crisis investment in old technologies completely stops. dividends in the model, where energy saving technologies become available are, for some years, higher than the case where no energy saving technology arrives. however, as a result of the arrival of the better technology, the old technology is gradually abandoned and its dividends slowly decay. the overall impact on market valuation of relatively higher wages and shorter life span for old capital results in a % decline in tobin’s average q. it is also important to mention that the present value of the above dividend flows assuming no change in interest rates after the energy crisis was only % higher than what results with flexible interest rates. thus, general equilibrium movements in the interest rate are not quantitatively relevant for understanding equity price movements in our model. . price induced innovation in energy-saving technologies we now examine the full fledged version of our model in a situation where energy prices and energy- cost shares in correspond to the - average for the u.s. economy and are expected to continue at that level for the infinite future. energy-saving technologies can be adopted after incurring a fixed cost and are subject to a learning curve. the model economy departs from a balanced growth path in which, given energy price expectations and adoption costs, energy-saving technologies are not adopted by the representative firm. we associate this equilibrium with the average behavior of the u.s. economy during - . on , energy prices rise unexpectedly and energy price expectations match the u.s. data from to . our objective is to determine the quantitative implications of the energy crisis for the market value of u.s. corporations. the equilibrium time series from the model economy after the energy price shock hits are summarized in figure . . . . . . . . . tobin's q (model) tobin's q (data) . . . . . . . energy/gdp (model) energy/gdp (data) . . . . . . . . . . . investment/output (model) investment/output (data) - % - % - % % % % % % gdp (model, %change) gdp (data, %change) figure : price induced innovation in energy saving technologies the behavior of energy prices from to gives firms enough incentives to pay the fixed costs associated with the development and adoption of energy-saving technologies. thus, the energy crisis gives rise to the endogenous obsolescence of existing capital and a decline in market value by %. the learning curve makes this drop in market value persistent. tobin’s q is % below its level up to . energy saving technologies gradually replace the old production methods and, after the total factor productivity of the new technology catches up with the old one, market values recover in a smooth fashion. as in the exogenous case, the trends in the energy to corporate gdp ratio from the model are consistent with those in the u.s. data. investment on the year of the energy crisis matches the data by construction. from to , the model’s investment- corporate gdp ratio tracks the movements in its data counterpart fairly well given we have not introduced investment subsidies into our analysis. the behavior of corporate gdp in the model is also qualitatively consistent with the observed trends in the u.s. data. . energy price expectations during the mid s the development and adoption of a new aggregate production technology is costly. with the low energy prices that prevailed during - it was not economically optimal to incur these costs. higher energy prices may have provided the incentives to do so, but only if this increase in energy prices was perceived as persistent. in what follows we provide some evidence suggesting that was indeed the case. the main source of our analysis is the energy information administration (eia) which, af- ter the energy crisis, was required by congress to report short and long-run forecasts for energy prices, energy production and consumption. to do so, the eia developed the project independence evaluation system (pies). the pies models energy demand and supply independently. energy demand for the different types of energy are assumed to depend on its price, and on the price of substitutes; demand is also assumed to depend on the level of economic activity, and on the ability of consumers and capital stocks to adjust to these factors. energy supply is estimated separately for oil, natural gas and coal. for each region and fuel type, reserve estimates are combined with the technologies and costs of finding and producing these fuels to estimate the costs of increasing supply. the pies then attempts to match these energy demands as a function of fuel, sector and price with the available supply in the regions which can supply these needs at the lowest price to find a balance of equilibrium. if supply is not available to satisfy the specific demands in an area, the prices are allowed to vary until supply and demand are brought into balance. according to the eia, energy prices were expected to remain at their level through as the following quote illustrates "...there is no significant likelihood of a considerable lower price for opec oil in this period ... most of the analytical emphasis is placed on a continuation of current prices (in dollars)." one year later the forecasts were even more pessimistic. the annual report to congress of the eia states: "prices for all energy fuels are forecast to increase in real terms through ." the energy price forecast of the eia is summarized in figure below: . . . . . . . . real price of energy (per btu, = ) eia forecast figure : real price of energy and eia forecast in its volume, the eia reports a survey of the "principal, most recent, long-term energy price projections". the purpose of the survey was to collate the prevailing long-term views projected by "prominent authorities." none of these forecasts predicted any decline in real energy prices through the details about the pies model can be found at appendixes a-e of the national energy outlook. national energy outlook. pages and . and all but one predicted that real energy prices in - would be significantly ( % on average) higher than during - . figure below illustrates that energy price forecasts produced by the eia were not able to predict the large drop in energy prices that occurred during the late s even after energy prices had started declining. real price of oil vs forecasted prices . . . . . . . . . real price per barrel ( = ) forecasted real price (low) forecasted real price (mid) forecasted real price (high) figure : real price of oil and forecasts in summary, energy price forecasts after the crisis of - predicted either constant or in- creasing trends in the medium term, and most of them expected prices to go up in the long run. furthermore, energy price forecasts could not foresee the huge decline that started around even when the decline had started. hence, there is evidence that suggests that energy price expectations during the mid s and early s pointed to a more pessimistic energy price behavior than what actually occurred. hence, the drop in market values generated in section should be considered as a lower bound of the impact of the energy crisis of the mid s. conclusion this paper employs a calibrated dynamic general equilibrium model to evaluate how much of the stock market crash of - can be accounted for by changes in energy prices and adoption of energy-saving technologies. in a world where capital is technology specific, and investment decisions are irreversible, we find that the observed changes in energy prices, together with the energy-saving technologies derived from the energy use series data, translate into a % drop in tobin’s average q. this corresponds to almost half of the observed drop in q of the mid- ’s. our analysis indicates that changes in energy prices should be part of any theory of the stock market collapse of - . see table . of the eia annual report to congress, volume ii, page . data appendix here we outline how the major series used in the figures were constructed. figures and . ratio of market value to replacement cost of tangible assets for corporations and to gdp market value of corporations was constructed using data from the flow of funds accounts of the united states (fof) issued by the board of governors of the federal reserve system (frb). in the fof, domestic corporations are divided into nonfinancial and financial corporate business. financial corporations are further divided to the following categories as listed in table f. : commercial banking, life insurance companies, other insurance companies, closed-end funds, exchange-traded funds, real estate investment trusts (reits) and brokers and dealers. our measure of market value reflects both equity value and debt of all domestic corporations, and all direct or indirect (through mutual funds) intercorporate holdings of corporate equity and debt has been netted out. to that effect market value of domestic corporations (mv) has been constructed as follows: mv = corporate equity issued by nonfinancial and financial corporate businesses + net finan- cial liabilities (i.e. total liabilities - total financial assets) of nonfarm nonfinancial corporate busi- nesses,commercial banks, life insurance companies, other insurance companies, closed-end funds, exchange-traded funds, reits, and security brokers and dealers. we construct the market value for energy-producing industries (the sum of coal mining, oil and gas extraction, petroleum, electric services and gas services) and subtract this from total mv to arrive at the market value of non-energy producing corporations. replacement cost of tangible assets of corporations was constructed using data from the fixed assets tables (fa) reported by the bureau of economic analysis (bea) and also from the fof. our measure of tangible assets include all nonresidential and residential fixed assets, plus inventories. corporate fixed assets are the sum of corporate nonresidential fixed assets and corporate residential fixed assets. stock of inventories held by nonfarm nonfinancial corporations is from the fof. we assume financial corporations hold no inventories as their inventory investment is zero in the product account, and we neglect inventories held by farm corporations since they are negligibly small. we subtract the capital stock of energy-producing corporations (coal mining, oil and gas extrac- tion, petroleum, electric services and gas services) from the total. this data was obtained from the bea table kcu. figure . energy prices relative to the gdp deflator we follow the methodology outlined in atkeson & kehoe [ ] and construct an energy price deflator from a weighted average of coal, natural gas, petroleum and electricity consumed in the commercial, industrial and the transportations sectors. this excludes residential consumption as we focus only on the business sector and also energy consumed by the electric power sector as in this data can be downloaded from the frb website at http://www.federalreserve.gov/releases/z /current/data.htm. this data can be downloaded from the bea website at http://www.bea.doc.gov/bea/dn/faweb/allfatables.asp. our model all energy is imported. we assume % of petroleum used in the transportation sector is not business related and subtract this from total energy-consumption. we also exclude energy consumption of energy-producing sectors since production in our model refers only to non-energy production. to do this, we assume that energy-consumption in these sectors are proportional to their value added and subtract the resultant from the total industrial energy consumption. we use quantity and price data reported in the annual energy review (aer) . the quantity of each type of energy (measured in units of btus) consumed in the commercial, industrial and the transportation sectors are from tables . c, . d, . e respectively. for prices we use consumer price estimates of energy (as businesses are consumers of energy) reported in table . and we label the price of energy for each type as pi. for each type of energy i, we add the consumption of that energy type in all sectors and call that qi. then, total energy expenditure is simply p i qitpit. we calculate real energy use using prices as the base year. hence real energy use equals to p i qitpi . the energy price deflator pt is simply the ratio of the total energy expenditure to total energy use: pt = p i qitpitp i qitpi the gdp deflator is constructed in the usual way from nominal and real gdp series reported in bea’s nipa tables . and . . figure . energy expenditure and use in the business sector total energy expenditures of thenon-energy producing business sector was calculatedas in figure . and then was divided by the nominal gdp of the non-energy producing business sector (from nipa).the total real energy use of the business sector (expenditure using prices) was calculated as explained for figure . . this number was divided by the real gdp of the business sector in prices. real gdp of the business sector data is from bea’s nipa table . . we subtract the value-added of the energy-producing sectors. these numbers are reported in dollars. we first construct a price deflator using nominal and real gdp of the business sector, readjust the level of the deflator such that = rather than . then we multiply this number with nominal gdp of business to get real gdp of business in dollars. computational appendix notice that, after the energy-saving technology has been introduced, the production set is convex. hence, the life-time utility associated to a competitive equilibrium where technology is already available can be obtained as a solution to the dynamic programming problem v(k , k ,p e) = max x ,x ,e ,e u(c)+ βv(k , k ,p e ) ( ) s.t. this data can be downloaded from the eia website at http://www.eia.doe.gov/emeu/aer/contents.html. c + x + x + p e (e + e ) = ( −τy)y xi ≥ , for i = , , where the laws of motion of energy prices and total factor productivity are as described in section . notice that energy prices and tfp growth are time invariant after a finite number of periods, which allows us to solve for function v by backwards induction. to obtain an approximated solution to the dynamic programming problem ( ) we employ the value function iteration algorithm with spline interpolation described in santos [ ]. the initial conditions of our problem imply that capital of type two is not available. moreover, a minimum size investment must be incurred before the energy-saving technology becomes available. this minimum size constraint introduces a non-convexity into the analysis. hence, we must solve directly for the recursive competitive equilibrium of this economy, which is characterized by: . the firm’s problem: w(k , p e) = max e ,x ,n ,d {( −τy)y −wn −pee −x −d}+ βv(k , k , p e ) if d ≥ c βw(k , p e ) if d < c . the household’s problem: h(s, pe) = max s ,c u(c)+ βh(s , pe ) s.t. c + v (s −s) = wn + ds s ≥ . . feasibility and market clearing constraints: c + x + p ee + d = ( −τy)y n = n s = . we obtain a numerical approximation to each of the above value functions using the value function iteration algorithm, for each given set of prices. finally, we solve for the set of prices that makes the household’s and firm’s choices compatible with market clearing and feasibility. references [ ] annual survey of manufactures, u.s. bureau of the census, various years. 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( ): "energy, the stock market, and the putty-clay investment model," american economic review, ( ), pp. - . untitled- © nature publishing group news reforms of us energy labs a 'daunting task' washington. the task force set up by hazel o'leary, the us secretary of energy, to advise her on "alternative futures" for the department of energy's vast network of laboratories has been warned that efforts at reform face great and perhaps insurmount- able difficulties. the panel has also been told by a former senior scientific adviser to the carter admin- istration that a crisis of identity in the labo- ratories reflects a similar crisis facing the department itself, which carter established in the wake of the middle east oil crisis in the s. the task force on the laboratories is chaired by robert galvin of the electronics company motorola, and is due to report next february. o'leary sees its report as a pre- emptive strike that could help her to reform the laboratories before congress looks for more drastic remedies. but with the labora- tory network providing high-technology jobs across so many states and congressional districts, her concern may be misplaced. the network employs , engineers and scientists and tens of thousands of sup- port staff. it is made up of the three atomic weapons laboratories - los alamos and sandia in new mexico and lawrence livermore, california - as well as a group of smaller but still substantial facilities, such as fermilab and argonne in illinois, and brookhaven in new york state. german minister takes on greens munich. in a direct challenge to the anti- nuclear policies ofthe state of hessen, the german federal environment minister, klaus t pfer, has promised to order the state government to grant permission for the completion of a new production plant for mixed oxide (mox) fuel elements for nu- clear reactors. construction of the plant, which is lo- cated in hanau and which would have been germany's only national source of mox fuel elements, has been suspended at the de- mand of the state government. but utility companies are doubtful aboutthe impact of t pfer's challenge, as they feel that he lacks the political stamina for the lengthy battle that would be required to restart the manufacture of fuel elements. mox production in germany, which is controlled by siemens, has fallen foul ofthe social democrat (sdp)/green coalition that took control ofthe government of hessen in . both parties are committed to phas- ing out nuclear power in germany. most of germany's nuclear reactors now use mox elements in addition to stand- ard uranium elements. butthe original mox production facility at hanau was closed down in by the state environment minister, josef fischer, a member of the green party, after two relatively minor con- tamination incidents. fischer has also continued to oppose the development of the new plant, which would have quadrupled the capacity of mox fuel produced to more than tonnes per year, and was originally scheduled to start production in . siemens had continued to contest the enforced closure of the old plant. last week, however, it decided to cut its losses and accept that the plant should be closed permanently. most of the costs of keeping the plant open but unproductive, estimated at more than dm million, had been borne by utilities. these have now agreed that the old plant should be closed, and are negotiating contracts with british nuclear fuels (bnfl) in britain and cogema in france to produce tonnes of mox fuel. who will produce the remaining tonnes needed to use up the plutonium to be extracted from waste fuel from germa- ny's reactors depends on the outcome of the battle over the new german mox plant. siemens and the utilities have already in- vested more than dml billion in the plant, which is per cent complete and would take around two years to bring into produc- tion once construction work started again. the companies are keen to see a return on their investment as soon as possible. the plant's director, jurgen krellmann, claims that permission to complete and operate it is being withheld for purely politi- cal reasons. but a spokesperson for the hessen environment ministry insists that the ministry's sole concern is forthe safety of plant workers and the local population. t pfer is now trying to break the stale- mate. but the situation is not straightfor- ward. although his federal ministry has ultimate responsibility for nuclear power in germany, the state government is respon- sible for safety. he accuses the hessen government of being technologiefeindlich (hostile to technology), but rnay find it diffi- cult in practice to force his will on fischer, as he must issue individual orders to ap- prove each technical step in the building programme, and this could amount to separate orders. instead, the utilities are hoping for a change in political mood after the october federal elections and next spring's hessen state elections. but this cannot be guaran- teed. the sop, which is currently leading the opinion polls forthe federal elections, is committed to phasing out nuclear power, and promises to ban the production and eventually the use of mox fuel elements all together. alison abbott at the panel's first meeting two weeks ago, galvin says that hearing the experts' warnings was a "valuable process" for the panel, and still believes that the time is ripe for reform of the laboratories. "this is a window of time when it is appropriate for people to listen to us," he says. "we are hoping that because the cold war is over, budgets are tight, and there's so much inter- est in industrial competitiveness, people will say that it is time to do something different." but solutions will be hard to find to the fundamental problem facing the laborato- ries, namely that government funding for their core tasks of developing both nuclear weapons and energy technologies has been heavily cut back, and replacement options lack credibility. lewis branscomb of harvard university told the members ofthe panel thattheirwork had been done many times before, but with- out any effect: previous studies had been "technocratic analyses that failed to take account ofthe political context" ofthe labo- ratories, he said. branscomb said that talk of increased 'technology transfer' out ofthe laboratories was "the wrong paradigm" for their future. "it implies that there are industrially valu- able technologies in the laboratories that need to be pushed [into the marketplace], and that is not the case." branscomb expressed concern that moves to save money in the network would have a greater effect on good science laboratories than on the larger but arguably less useful weapons laboratories, as the former had less political clout. he also came close to calling for the department of energy itselfto be broken up, arguing that the problem of the laboratories is directly linked to the problems that the department faces. "there is an identity crisis in the labs because there is an identity crisis in the department," branscomb said. both seem equally adrift, with no en- ergy crisis to solve or atomic bombs to build. congress is also wrestling with the ques- tion of a new mandate for the laboratories. it may pass a bill this summer, ifthe chairman of the house of representatives science committee, george brown (democrat, cali- fornia), can sort out a demarcation dispute with john dingell (democrat, michigan) chairman of the energy and commerce committee and agree on a house version that can be reconciled with a bill already passed by the senate. some voices may demand drastic action. roscoe bartlett (republican, maryland), for example, is said to be considering moving an amendment on the floor of the house calling for some of the laboratories to be closed down. but even in this cost-cutting congress, there is no groundswell of sup- port for such a measure. colin macilwain nature . vol . may 	reforms of us energy labs a 'daunting task' butanol production from renewable biomass by clostridia review butanol production from renewable biomass by clostridia yu-sin jang a, , alok malaviya a, , changhee cho a, joungmin lee a, sang yup lee a,b,⇑ a metabolic and biomolecular engineering national research laboratory, department of chemical and biomolecular engineering (bk program), bioprocess engineering research center, center for systems and synthetic biotechnology, institute for the biocentury, kaist, republic of korea b department of bio and brain engineering and bioinformatics research center, kaist, republic of korea h i g h l i g h t s " butanol is an important industrial chemical as well as an advanced biofuel. " we review the use of various carbon sources on fermentation performance. " we review advanced fermentation and recovery processes for butanol production. g r a p h i c a l a b s t r a c t a r t i c l e i n f o article history: received may received in revised form july accepted july available online august keywords: biomass butanol clostridium fermentation recovery a b s t r a c t global energy crisis and limited supply of petroleum fuels have rekindled the worldwide focus towards development of a sustainable technology for alternative fuel production. utilization of abundant renew- able biomass offers an excellent opportunity for the development of an economical biofuel production process at a scale sufficiently large to have an impact on sustainability and security objectives. addition- ally, several environmental benefits have also been linked with the utilization of renewable biomass. butanol is considered to be superior to ethanol due to its higher energy content and less hygroscopy. this has led to an increased research interest in butanol production from renewable biomass in recent years. in this paper, we review the various aspects of utilizing renewable biomass for clostridial butanol produc- tion. focus is given on various alternative substrates that have been used for butanol production and on fermentation strategies recently reported to improve butanol production. � elsevier ltd. all rights reserved. . introduction butanol is an important industrial chemical and is also consid- ered as a superior liquid fuel with a potential to replace gasoline (dürre, ; lee et al., ; papoutsakis, ). research effort towards the efficient production of butanol from sustainable and renewable carbon sources has steadily been progressing. based on advances in biotechnology and process engineering, new fer- mentation processes are being developed for converting the abun- dantly available biomass to butanol (dürre, ; lee et al., ; papoutsakis, ). butanol has traditionally been produced by anaerobic fermentation of sugar substrates using various species of solventogenic clostridia (jones and woods, ). except for the solventogenic clostridia, it is believed that no genus among the bacteria, archea and eucarya is efficient enough to naturally produce butanol (qureshi et al., ). treatment of biomass for the extraction of fermentable sugars results in a mixture of sugar substrates, mainly pentoses, hexoses, and disaccharide. clostridium sp. are known to have the capability of utilizing simple and complex sugars, including both pentose and - /$ - see front matter � elsevier ltd. all rights reserved. http://dx.doi.org/ . /j.biortech. . . ⇑ corresponding author at: department of chemical and biomolecular engineer- ing, kaist, daehak-ro, yuseong-gu, daejeon – , republic of korea. fax: + . e-mail address: leesy@kaist.ac.kr (s.y. lee). these authors contributed equally to this work. bioresource technology ( ) – contents lists available at sciverse sciencedirect bioresource technology j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / b i o r t e c h http://dx.doi.org/ . /j.biortech. . . mailto:leesy@kaist.ac.kr http://dx.doi.org/ . /j.biortech. . . http://www.sciencedirect.com/science/journal/ http://www.elsevier.com/locate/biortech hbrp publication page - . all rights reserved page research and reviews on experimental and applied mechanics volume issue development and fabrication of solar vapour absorption refrigeration system using parabolic solar trough j.sidharthayadav *, manikanteswar rao , subrat ku. barik , raghu engineering college (autonomous), visakhapatnam sri sivani college of engineering, srikakulam *corresponding author e-mail id:- siddharthayadav.j@raghuenggcollege.in abstract as the saying goes, "there is no energy crisis, only a crisis of ignorance”. with the minds of research along with scientific investigation, a pathway has led to deep dive into renewable energy sources. in the era of energy crisis renewable energy is seen as a farsighted option with great capability and endurance. this paper deals with application of solar thermal energy with vapor absorption system. in vapor absorption, system heat energy is taken as source of input energy unlike mechanical energy in vapour compression refrigeration system. the performance characteristics and evaluation depends on heat energy supplied and pump work used in the refrigeration system .hence, here idea of experimental setup developed from this thought that if the heat energy required for the process is extracted from the solar energy and supplied to the generator then energy requirement to the generator can be reduced. hence, our project novelty is based on the running a vapour absorption refrigeration system using the heat energy extracted from solar energy by using a parabolic solar heat collector. this heat is used to supply the heat required in the generator for the system. hence, our result of experiment would aim for generation where the input work of electrical energy is given only through pump and other sources of input work are removed. air-conditioner and refrigerator uses % of domestic energy utilized. this work provides a solution for this high energy consuming machines. we hope to take a small step in this direction for future development and establishment of new advancements in this regard. keywords:-renewable energy, vapour absorption, heat energy, parabolic solar heat collector, solar thermal energy, pump work introduction development of a country depends on the per capita energy consumption of the people of that country. it is deemed that more the energy consumption more prosperous the nation is. in the present scenario, the same case is applicable but with a small change of utilizing clean energy which is environmental friendly. as rightly said by martin rees “we do not fully understand the consequences of rising population and increasing energy consumption on the interwoven fabric of atmosphere, water, land and life.” there has been ever increased need for utilizing clean energy and specially dealing with the refrigerants causing the depletion of ozone layer. hence the need of hour comes with the utilization of renewable sources of energy so to find a solution in this path few literature surveys was made like sorawit kaewpradub et al[ ] found a way to utilize waste heat of engine exhaust from automobiles in generating refrigerating effect. piyush mahendru et al[ ] in their paper studied about the analysis of lithium bromide, water vapor absorption refrigeration system using the mole concentration concept. pongsid srikhirin et al[ ] studied about the various hbrp publication page - . all rights reserved page research and reviews on experimental and applied mechanics volume issue vapor absorption refrigeration systems present and the working fluids which may be used to get various outputs. arturo gonzález gilstudied [ ] about solar air cooling on single & double effect lithium bromide vapor absorption refrigeration system. benjamin bronsema [ ] identified the problems faced in hybrid ventilation systems and provided certain solutions to them. t. o. ahmadu[ ] studied about a lithium bromide chiller, which gave a arakerimath [ ] studied about solar vapour absorption cooling system utilizing parabolic solar dish collector where the c.o.p was obtained to be . for the cycle. joydeep chakraborty et al [ ] studied about lithium bromide vapor absorption system using solar energy. anan pongtornkulpanich [ ] studied about a new pair of absorbent and refrigerant in vapour absorption system using activated carbon and methanol providing the required heat through solar energy. soteris kalogirou [ ] studied about designing a lithium bromide vapor absorption refrigerator providing the design conditions necessary for the heat exchangers. shekhar d. thakre et al [ ] presented about the cooling system in truck by using vapor absorption system taking source from the waste heat of automobiles. salem m. osta-omar et al[ ] studied about the concentration of absorbent and refrigerant required in a vapor absorption system. the concentration of aqueous solution of lithium bromide was found using electrical conductivity and temperature measurements. k.balaji et al[ ] studied about vapor absorption system using waste heat source from sugar industry and designed a hypothetical model for the li br, water refrigeration system. jaspalsinh b dabhi et al[ ] studied about various pairs for adsorption cooling systemsand their outputs. the various pairs included silica gel -water, activated carbon - ammonia, zeolite –water, metal organic framework materials. makena harish et al[ ] studied about design of vapour absorption refrigeration system of . kw capacity using solar water heaters. rotchana prapainop et al [ ] studied about properties of refrigerant & how different refrigerant properties affects the performance of the system. joyeep chakraborty et al [ ] described about the lithium bromide refrigeration system using solar energy as the heat source. shabari girish k.v.s. et al[ ] studied about a detailed case study for a lithium bromide refrigeration system. abhishek ghodeshwar [ ] and team studied comparison and analysis of vapor compression and absorption refrigeration system. prashant sharma et al[ ] studied about thermal analysis of vapor absorption refrigeration system using solar energy. gaps identified from literature survey although vapor absorption refrigeration outstands vapor compression system in many aspects like using non-harmful refrigerants, using clean energy and reducing carbon emissions indirectly most of the literature work has been done on lithium bromide refrigeration system. very little work is done in the recent times on ammonia water vapour absorption system. since ammonia’s freezing point (- c) is very less compared to lithium bromide which is a better option considering the application in the field of refrigeration. hence based on the literature survey it is decided to conduct an experimental analysis on ammonia water based vapor absorption refrigeration system aiming for obtaining better results compared to lithium bromide refrigeration system. the novelty of this paper is in the utilization of solar thermal (heat) energy applications for producing refrigerating effect using ammonia water as the working pair. in vapour absorption system, we require heat energy for the separation of refrigerant and hbrp publication page - . all rights reserved page research and reviews on experimental and applied mechanics volume issue absorbent. the heat source required for this is supplied with the help of solar heat supplied from a parabolic solar collector. once the connections are made, coefficient of performance is calculated and the results are analyzed. solution to energy consumption and energy saving for future is eminently visible from the source of renewable energy. idea of setting an interlink for obtaining refrigerating effect with solar heat generated from parabolic solar trough not only overcomes the deficiency of energy consumption but also deals with overcoming the high end solution for ozone layer depletion which is a gigantic problem nowadays. working principle of absorption system: in a vapor absorption system two fluids are used which are the absorbent and refrigerant. absorbent is a substance which absorbs the refrigerant causing the pressure to reduce. as the refrigerant vapor gets absorbed the temperature of the refrigerant gets reduced due to vaporization of the refrigerant. this basic process causes the refrigerating effect. as this occurs the absorbent becomes more and more diluted due to refrigerant getting absorbed into it and hence to separate this again heating is used to bring the absorber back to its normal state. hence, by the process of supplying heat energy the refrigerating effect is produced in a cyclic process as shown in figure . fig. :-working process of vapor absorption system vapor absorption cooling system equipments condenser: the condenser converts the refrigerant vapor into liquid refrigerant .here an air-cooled fin type condenser is used for getting the required heat transfer in the process. the refrigerant used here (ammonia) enters as vapor and exits at the outlet as liquid refrigerant. expansion valve: the high pressure liquid refrigerant leaving the condenser enters the expansion valve and reduces the pressure as it leaves out of the system .a capillary tube is used here as an expansion valve which brings the down the pressure in the system. evaporator: this low-pressure low temperature liquid refrigerant enters the evaporator whose function is to absorb the heat in the refrigerated space and produce the required refrigerating effect of the system. the refrigerant enters as liquid condition in evaporator and leaves as vapor or superheated vapor from the evaporator. hbrp publication page - . all rights reserved page research and reviews on experimental and applied mechanics volume issue absorber: the function of an absorber is to gulp the refrigerant formed in the evaporator. it absorbs the vapor refrigerant coming out of the evaporator and forms a solution in the absorber system. here, liquid water is used as an absorbent as water has great affinity towards ammonia vapors as shown in figure . generator: the generator is used to separate this solution formed in the absorber into their original forms of refrigerant and absorbent. the generator takes heat as the source, and separates the solution into refrigerant and absorbent and helps it to flow back into the condenser and completes the cycle. experimental set-up solar parabolic trough collector it consists of a solar collector shaped in a parabola for obtaining maximum concentration of solar radiation. here, the parabolic solar trough collector fabricated using aluminum plates with plywood was used. initially plywood is setup, on which aluminum sheets pasted. a pipe situated at the focus of the parabola so that the solar radiation on the collector will be concentrated on it and the refrigerant flowing inside the pipe gets heated. here, this works as a generator for separating the refrigerant and absorbent as shown in figure . fig. :-fabrication of solar parabolic trough collector fig. :-condenser, evaporator and absorber unit table. :-details of components used in the experiment s. no. component material specification size units parabolic collector aluminum tube metre condenser copper windings . metre expansion valve copper windings . metre absorber iron . x . metre pump plastic watt thermocouples digital celsius, kelvin hbrp publication page - . all rights reserved page research and reviews on experimental and applied mechanics volume issue the experiment was conducted based on the data provided in table . all the equipment stated above were purchased and connected in a cyclic manner stated in the working principle. once the equipment were ready, the refrigerant was filled in the condenser under the supervision of local refrigerant technician. the experimental set up was ready and it was connected to the parabolic collector fabricated earlier. once this entire set up was ready, we started with the experiment and took the values of temperatures by using digital thermocouples at various required connections of condenser, generator & evaporator. based on these values of temperature readings we found the coefficient of performance at various timings of the day as per the availability of solar energy in the day. on completion of it we collected the values of temperatures for a week and the average instantaneous coefficient of performance was found. the experiment was made on the following assumptions:  the flow is considered as steady and reversible.  pure refrigerant is flowing in the condenser, expansion valve and evaporator.  there is no pressure loss in the system.  changes in kinetic and potential energy are negligible in the system. calculations tg: temperature in the generator tc: temperature in the condenser te: temperature in the evaporator day : / / s.no. time tg tc te c.o.p : am . : pm . : pm . . day : / / s.no. time tg tc te c.o.p : am . : pm . : pm . . day : / / s.no. time tg tc te c.o.p : am . : pm . : pm . . day : / / s.no. time tg tc te c.o.p : am . : pm . : pm . . day : / / s.no. time tg tc te c.o.p : am . : pm . : pm . . day : / / s. no. time tg tc te c.o.p : am . : pm . : pm . . day : / / s.no. time tg tc te c.o.p : am . : pm . : pm . . coefficient of performance = [ 𝐑𝐞𝐟𝐫𝐢𝐠𝐞𝐫𝐚𝐭𝐢𝐧𝐠 𝐞𝐟𝐟𝐞𝐜𝐭 𝐢𝐧 𝐭𝐡𝐞 𝐞𝐯𝐚𝐩𝐨𝐫𝐚𝐭𝐨𝐫 𝐇𝐞𝐚𝐭 𝐬𝐮𝐩𝐩𝐥𝐢𝐞𝐝 𝐢𝐧 𝐭𝐡𝐞 𝐠𝐞𝐧𝐞𝐫𝐚𝐭𝐨𝐫 ] co.p=[ 𝑻𝒈−𝑻𝒄 𝑻𝒈 ] ∗ [ 𝑻𝒆 𝑻𝒄 −𝑻𝒆 ] day c.o.p = [ 𝟑𝟒𝟓−𝟑𝟐𝟕 𝟑𝟒𝟓 ] ∗ [ 𝟐𝟖𝟓 𝟑𝟐𝟕−𝟐𝟖𝟓 ] = . hbrp publication page - . all rights reserved page research and reviews on experimental and applied mechanics volume issue c.o.p = [ 𝟑𝟓𝟑−𝟑𝟑𝟓 𝟑𝟓𝟑 ] ∗ [ 𝟐𝟖𝟕 𝟑𝟑𝟓−𝟐𝟖𝟕 ] = . c.o.p = [ 𝟑𝟑𝟗−𝟑𝟐𝟑 𝟑𝟑𝟗 ] ∗ [ 𝟐𝟖𝟓 𝟑𝟐𝟑−𝟐𝟖𝟓 ] = . average c. o. p day = [ 𝑪𝑶𝑷𝟏+𝑪𝑶𝑷𝟐+𝑪𝑶𝑷𝟑 𝟑 ] = [ 𝟎.𝟑𝟓𝟒+𝟎.𝟑𝟎𝟓+𝟎.𝟑𝟓𝟑 𝟑 ] = . day c.o.p = [ 𝟑𝟒𝟐−𝟑𝟑𝟎 𝟑𝟒𝟐 ] ∗ [ 𝟐𝟖𝟔 𝟑𝟑𝟎−𝟐𝟖𝟔 ] = . c.o.p = [ 𝟑𝟔𝟎−𝟑𝟒𝟐 𝟑𝟔𝟎 ] ∗ [ 𝟐𝟖𝟒 𝟑𝟒𝟐−𝟐𝟖𝟒 ] = . c.o.p = [ 𝟑𝟑𝟓−𝟑𝟐𝟓 𝟑𝟑𝟓 ] ∗ [ 𝟐𝟖𝟓 𝟑𝟐𝟓−𝟐𝟖𝟓 ] = . average c. o. p day = [ 𝑪𝑶𝑷𝟏+𝑪𝑶𝑷𝟐+𝑪𝑶𝑷𝟑 𝟑 ] = [ 𝟎.𝟐𝟐𝟖+𝟎.𝟑𝟓𝟔+𝟎.𝟐𝟏𝟐 𝟑 ] = . day c.o.p = [ 𝟑𝟒𝟗−𝟑𝟑𝟎 𝟑𝟒𝟗 ] ∗ [ 𝟐𝟖𝟕 𝟑𝟑𝟎−𝟐𝟖𝟕 ] = . c.o.p = [ 𝟑𝟔𝟐−𝟑𝟒𝟒 𝟑𝟔𝟐 ] ∗ [ 𝟐𝟖𝟖 𝟑𝟒𝟒−𝟐𝟖𝟖 ] = . c.o.p = [ 𝟑𝟒𝟖−𝟑𝟑𝟐 𝟑𝟒𝟖 ] ∗ [ 𝟐𝟖𝟒 𝟑𝟑𝟐−𝟐𝟖𝟒 ] = . average c. o. p day = [ 𝑪𝑶𝑷𝟏+𝑪𝑶𝑷𝟐+𝑪𝑶𝑷𝟑 𝟑 ] = [ 𝟎.𝟑𝟔𝟑+𝟎.𝟐𝟓𝟔+𝟎.𝟐𝟕𝟐 𝟑 ] = . day c.o.p = [ 𝟑𝟓𝟕−𝟑𝟑𝟑 𝟑𝟓𝟕 ] ∗ [ 𝟐𝟖𝟓 𝟑𝟑𝟑−𝟐𝟖𝟓 ] = . c.o.p = [ 𝟑𝟔𝟏−𝟑𝟑𝟏 𝟑𝟔𝟏 ] ∗ [ 𝟐𝟖𝟕 𝟑𝟑𝟏−𝟐𝟖𝟕 ] = . c.o.p = [ 𝟑𝟒𝟔−𝟑𝟐𝟗 𝟑𝟒𝟔 ] ∗ [ 𝟐𝟖𝟓 𝟑𝟐𝟗−𝟐𝟖𝟓 ] = . average c. o. p day = [ 𝑪𝑶𝑷𝟏+𝑪𝑶𝑷𝟐+𝑪𝑶𝑷𝟑 𝟑 ] = [ 𝟎.𝟑𝟗𝟗+𝟎.𝟓𝟒𝟐+𝟎.𝟑𝟏𝟖 𝟑 ] = . day c.o.p = [ 𝟑𝟔𝟐−𝟑𝟒𝟎 𝟑𝟔𝟐 ] ∗ [ 𝟐𝟖𝟒 𝟑𝟒𝟎−𝟐𝟖𝟒 ] = . c.o.p = [ 𝟑𝟓𝟖−𝟑𝟑𝟔 𝟑𝟓𝟖 ] ∗ [ 𝟐𝟖𝟔 𝟑𝟑𝟔−𝟐𝟖𝟔 ] = . c.o.p = [ 𝟑𝟒𝟖−𝟑𝟑𝟖 𝟑𝟒𝟖 ] ∗ [ 𝟐𝟖𝟖 𝟑𝟑𝟖−𝟐𝟖𝟖 ] = . average c. o. p day = [ 𝑪𝑶𝑷𝟏+𝑪𝑶𝑷𝟐+𝑪𝑶𝑷𝟑 𝟑 ] = [ 𝟎.𝟑𝟎𝟖+𝟎.𝟑𝟓𝟏𝟓+𝟎.𝟏𝟔𝟓𝟓 𝟑 ]= . day c.o.p = [ 𝟑𝟒𝟎−𝟑𝟐𝟔 𝟑𝟒𝟎 ] ∗ [ 𝟐𝟖𝟑 𝟑𝟐𝟔−𝟐𝟖𝟑 ] = . c.o.p = [ 𝟑𝟓𝟔−𝟑𝟑𝟖 𝟑𝟓𝟔 ] ∗ [ 𝟐𝟖𝟔 𝟑𝟑𝟖−𝟐𝟖𝟔 ] = . c.o.p = [ 𝟑𝟔𝟎−𝟑𝟐𝟖 𝟑𝟔𝟎 ] ∗ [ 𝟐𝟖𝟖 𝟑𝟐𝟖−𝟐𝟖𝟖 ] = . hbrp publication page - . all rights reserved page research and reviews on experimental and applied mechanics volume issue average c. o. p day = [ 𝑪𝑶𝑷𝟏+𝑪𝑶𝑷𝟐+𝑪𝑶𝑷𝟑 𝟑 ] = [ 𝟎.𝟐𝟕𝟏+𝟎.𝟐𝟕𝟖+𝟎.𝟔𝟒𝟎 𝟑 ] = . day c.o.p = [ 𝟑𝟔𝟎−𝟑𝟒𝟐 𝟑𝟔𝟎 ] ∗ [ 𝟐𝟖𝟖 𝟑𝟒𝟐−𝟐𝟖𝟖 ] = . c.o.p = [ 𝟑𝟔𝟐−𝟑𝟒𝟔 𝟑𝟔𝟐 ] ∗ [ 𝟐𝟖𝟔 𝟑𝟒𝟔−𝟐𝟖𝟔 ] = . c.o.p = [ 𝟑𝟓𝟖−𝟑𝟒𝟎 𝟑𝟓𝟖 ] ∗ [ 𝟐𝟖𝟖 𝟑𝟒𝟎−𝟐𝟖𝟖 ] = . average c. o. p day = [ 𝑪𝑶𝑷𝟏+𝑪𝑶𝑷𝟐+𝑪𝑶𝑷𝟑 𝟑 ] = [ 𝟎.𝟐𝟔𝟔+𝟎.𝟐𝟏𝟏+𝟎.𝟐𝟕𝟖 𝟑 ] = . overall average instantaneous c.o.p = [ 𝑨𝑽𝑮 𝑪𝑶𝑷 𝑫𝑨𝒀𝟏+𝑨𝑽𝑮 𝑪𝑶𝑷 𝑫𝑨𝒀𝟐+𝑨𝑽𝑮 𝑪𝑶𝑷 𝑫𝑨𝒀𝟑+𝑨𝑽𝑮 𝑪𝑶𝑷 𝑫𝑨𝒀𝟒+𝑨𝑽𝑮 𝑪𝑶𝑷 𝑫𝑨𝒀𝟓+𝑨𝑽𝑮 𝑪𝑶𝑷 𝑫𝑨𝒀𝟔+𝑨𝑽𝑮 𝑪𝑶𝑷 𝑫𝑨𝒀𝟕 𝟕 ] =[ 𝟎.𝟑𝟑𝟕+𝟎.𝟐𝟔𝟓+𝟎.𝟐𝟗𝟕+𝟎.𝟒𝟏𝟗+𝟎.𝟐𝟕𝟓+𝟎.𝟑𝟗𝟔+𝟎.𝟐𝟓𝟐 𝟕 ] = . so, overall average c.o.p. obtained as . for this system conclusion in the present generation, the motto for development is “first & fast” rather than “slow& steady”. therefore, here we used solar heat energy for heat required in the generator. harnessing solar energy into panels is a technological stuff giving an overall output of maximum % only but when we use solar heat from collectors, we could generate a great cause and effect in producing refrigeration effect .although the temperature difference obtained here is of low range ( to ) degrees maximum. an improvisation in this temperature difference can be obtained by changing the concentration levels of absorbent and refrigerant pairs or by considering other design factors of evaporators, condensers, length between the evaporator and parabolic solar trough etc. hence, this may be a pathway for the future scope of development in this direction. furthermore utilizing this device in the application of air conditioning has futuristic approach rather than refrigeration .hence with the present generation facing the crisis of energy generation, consumption and utilization this method forms a pathway in finding a small step towards a mighty development in the field of energy saving design of appliances. reconsidering the designs in a proper way would lead to utilization in every domestic household refrigeration and air conditioning appliance connected through solar energy, which is safe, clean & simple technology. as the saying goes “nature satisfies everyone’s need not greed” so this a definite and promising solution for overcoming the problems of ozone depletion , high energy consumption & global warming by utilizing nature’s greatest brightest and everlasting source “the sun”. references . kaewpradub, s., sanguanduean, p., katesuwan, w., chimres, n., punyasukhananda, p., asirvatham, l. g., ... & wongwises, s. 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( ). thermodynamic analysis of lithium bromide-water (libr-h o) vapor absorption refrigeration system based on solar energy. international research journal of engineering and technology (irjet), ( ). microsoft word - - _s_etasr_v _n _pp - engineering, technology & applied science research vol. , no. , , - www.etasr.com saand et al.: effect of metakaolin developed from local soorh on fresh properties and compressive … effect of metakaolin developed from local soorh on fresh properties and compressive strength of self- compacted concrete abdullah saand department of civil engineering quaid-e-awam university of engineering, science and technology nawabshah, pakistan abdullah.saand@gmail.com karam ali jamali department of civil engineering quaid-e-awam university of engineering, science and technology nawabshah, pakistan tespublic@yahoo.com manthar ali keerio department of civil engineering quaid-e-awam university of engineering, science and technology nawabshah, pakistan mantharali @quest.edu.pk tariq ali department of civil engineering quaid-e-awam university of engineering, science and technology, nawabshah, pakistan tariqdehraj@gmail.com nadeem-ul-karim bhatti department of civil engineering quaid-e-awam university of engineering, science and technology, nawabshah, pakistan knadeem_b@quest.edu.pk abstract—this paper presents the fresh properties of self- compacting concrete (scc) containing metakaolin (mk) produced by calcination of the natural material soorh of district thatta sind in pakistan. five mixes were tested, including four mk mixes replacing - % of cement, with . water/binder (w/b) ratio. the fresh properties of the sccs were evaluated using slump flow, t , v-funnel, j ring, l-box and sieve segregation tests. compressive strength of the control and the mk scc was also investigated. the fresh concrete test results revealed that scc could be developed by substituting cement with local mk, using % superplasticizers and without using a viscosity-modifying amplifier. the scc with % replacement of cement with local mk showed maximum compressive strength, which was . % higher than the control specimen’s without mk. keywords-metakaolin; self-compacting concrete; soorh i. introduction self-compacting concrete (scc) is a highly flowable concrete, which can be installed and compacted without any vibration in complex or dense reinforced formworks. in order to achieve such behavior, the main requirements of fresh scc are filling ability, passing ability and very high segregation resistance. the first two properties can be achieved by using a high-range water reducer (hrwr) admixture. to secure the stability/cohesion of the mix, a large quantity of powder materials and/or viscosity-modifying admixture (vma) is required. according to [ ], the term powder is defined for materials of particle size smaller than . mm, which include a fraction of aggregate additions and cement. portland cement is a high energy-intensive product. on the other hand, about % of total co emissions are produced by the cement industry [ ]. in addition, some disadvantages in the properties of concrete have been reported as the cement content exceeded a specified value [ ]. to minimize these negative effects, the requirement to increase powder content in scc is usually met by using additions. for this purpose, various studies have been conducted on the usage of different additions for partially replacing cement in scc or self-compacted mortar such as marble powder [ , ], limestone powder [ ], basalt powder [ , ], fly ash [ – ], slag [ , ], mk [ - ], and other materials[ - ]. today global warming and energy crisis are major issues. the manufacture of one ton of cement emits approximately . tons of co into the atmosphere, which accounts about the - % of worldwide co emissions [ , ]. moreover, cement production emissions include also so and nox [ , ]. cement production requires huge energy, as it needs temperatures of - ºc, adding up to the energy crisis in many countries, such as pakistan, where the cost of cement is rising resulting in an overall rise in the construction cost. this study proposes a method that increases the properties of scc and reduces the cement production, reducing consequently both co emissions and construction cost, by replacing cement with local mk. ii. materials used a. cement ordinary portland cement (opc) from a brand named lucky, has been used in this research. its chemical composition and physical properties are shown in table i. b. fine aggregates the aggregates used are composed of hill sand passing from . mm, crushed stone passing from mm and retained on . mm sieves. corresponding author: tariq ali engineering, technology & applied science research vol. , no. , , - www.etasr.com saand et al.: effect of metakaolin developed from local soorh on fresh properties and compressive … c. local metakaolin local metakaolin (mk) was produced from local natural material soorh available at district thatta sindh in pakistan, by calcination at ºc for hours. the mk was used as cement replacement at various dosages, after sieving it from a sieve no . the chemical composition and physical properties comparison of opc, soorh and developed mk are presented in table i. table i. chemical composition of materials [ ] constituents percentage by cement weight percentage by soorh weight percentage by mk weight sio . . . % al o . . . % cao . - . % mgo . . % fe o . . . % k o - . . % na o - . . % tio - . . % in o - - . % loi (%) . . . blaine specific surface area (cm /g) iii. mixture proportion based on the w/b ratio of . , scc mixtures were prepared following [ ]. the reference concrete was prepared by only opc while in the other mixtures opc was partially replaced by mk at %, %, % and % of the cement’s weight. details of mix proportions are exhibited in table ii. table ii. mix proportions concrete mix cement (kg/m ) mk (kg/m ) total binder (kg/m ) water (kg/m ) fa (kg/m ) ca (kg/m ) sp (%) cm - mk mk mk mk m/b= . iv. test procedure the fresh properties of scc have been studied out by using the method specified in [ ]. the filling ability tests respected slump flow using v-funnel and t flow time test, while passing ability tests, such as j-ring and l-box, were also carried out. moreover, sieve segregation test was carried out. various trial mixes with and without superplasticizers were prepared to develop the scc. twenty eight days after the development of the control and the modified mk scc, the compressive strength of concrete was evaluated using bs en - . v. results and discussion a. slump flow slump flow test was used to assess the horizontal free flow of scc in the absence of obstructions. the diameter of the concrete circle is a measure of the filling ability of concrete [ ]. the results of slump flow test for the mixtures are shown in figure . fig. . slump flow of control and metakaolin scc the recommended values of slump flow in [ ] are - mm. without using superplasticizers and using only % superplastericizers, the observed slump flow of control and mk scc was less than the recommended. by using % superplasticizers the slump flow of control and mk scc was within the recommended range. as the quantity of mk increased the slump flow increased due to mk’s less specific surface area as compared to cement. b. v-funnel this test was developed in japan and used in [ ]. the v- funnel test is used to determine the filling ability (flowability) of the concrete with a maximum aggregate size of mm.the results of the v-funnel test are shown in figure . fig. . v-funnel of control and metakaolin self compacted concrete the recommended values [ ] of the v-funnel are - sec [ ]. without using superplasticizers and using % superplasticizers, the observed v-funnel flow of the control and the mk sccs exceeded the recommended range. by using % superplasticizers the v-funnel of the control and the mk scc were within the recommended range. as the quantity of mk increased, the v-funnel time decreased. c. t flow t flow test was used to assess the horizontal free flow of scc in the absence of obstructions. the results of the t flow tests are shown in figure . engineering, technology & applied science research vol. , no. , , - www.etasr.com saand et al.: effect of metakaolin developed from local soorh on fresh properties and compressive … fig. . t flow of control and metakaolin scc the recommended values of t flow time are - sec [ ]. without using superplasticizers and using % superplastericizers, the observed t flow time of the control and the mk scc exceeded the recommended. by using % superplasticizers, the t values of the control and the mk scc were observed within the recommended range. as the quantity of mk increased the t flow decreased. d. j-ring the j-ring test was developed at the university of paisley and it is used to determine the passing ability of the concrete. the results j-ring tests are shown in figure . fig. . j-ring of control and metakaolin self compacted concrete the recommended values of j ring test [ ] are - mm. without using superplasticizers and using % superplastericizers, the observed values of the control and the mk scc exceeded the recommended. by using % superplasticizers the observed j-ring values of the control and the mk scc were within the recommended range. as the quantity of mk increased, j-ring decreased. e. l-box l-box test is used to assess the flow of the concrete and the extent to which it is subject to blocking by reinforcement. the results of l-box tests are shown in figure . the recommended values for the l-box test are . - . . without using superplasticizers and using % superplasticizer, the observed values of control and the mk scc exceed the recommended range. by using % superplasticizers the l-box value of control and the mk scc were observed within the recommended range. again, as the quantity of mk increased the l-box is decreased. fig. . l-box ratio of control and metakaolin self compacted concrete f. sieve segregation test the sieve segregation test was developed by gtm to assess segregation resistance (stability). the results of the sieve segregation tests are shown in figure . fig. . sieve segregation of control and metakaolin self compacted concrete the recommended range of sieve segregation is - % [ ]. without using superplasticizers and using % superplasticizers, the observed values of the control and the mk scc exceeded the recommended range. by using % superplasticizers, the j- ring values of control and mk scc were within the recommended range. as the quantity of mk increased the sieve segregation increased. g. compressive strength the results of compressive strength tests are shown in figure . the test results show that the compressive strength of - % mk scc increased compared to the control or the other mk sccs. the % mk mixture exhibited maximum compressive strength , being . % higher than the one of the control mix. vi. conclusion this study evaluated the fresh properties of scc containing local mk. results showed that all the fresh properties of scc containing local mk with % superplasticizers like passing ability, filling ability, and sieve segregation tests are within the recommended range. the fresh concrete test results revealed engineering, technology & applied science research vol. , no. , , - www.etasr.com saand et al.: effect of metakaolin developed from local soorh on fresh properties and compressive … that scc could be developed substituting cement with local mk up to %, by using % superplasticizers, without using any viscosity-modifying admixture. compressive strength of - % mk mixtures was increased, while in higher mk mixtures the compressive strength decreased. the % mk scc had the maximum compressive strength, which was . % higher than the control mix without mk. fig. . compressive strength of control and metakaolin self compacted concrete acknowledgement authors acknowledge the quaid-e-awam university for the provision of the necessary funds. references [ ] efnarc, the european guidelines for self-compacting concrete; specification production and use, available at: http://www.efnarc.org/pdf/sccguidelinesmay .pdf, [ ] r. zerbino, g. giaccio, g. c. isaia, “concrete incorporating rice-husk ash without processing”, construction and building materials, vol. , no. , pp. – , [ ] a. m. neville, properties of concrete, vol. , longman, [ ] e. guneyisi, m. gesoglu, e. ozbay, “effects of marble powder and slag on the properties of self compacting mortars”, materials and structures, vol , no. , pp. - 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- -z editorial transactions of tianjin university: join us to step up to the next generation of sustainable energy jinlong gong published online: january © the author(s) due to a steady increase in world’s population and huge demands of fossil fuels and its products, the global energy crisis has become more and more visible as the biggest chal- lenge that impedes the sustainable development of human- ity. as a result of advances in industry and technology and various forms of pollution from anthropogenic activities, our earth has taken a great toll with massive emission of green house gases, causing the rise of sea levels, deforesta- tion and extreme weather. thus, to address climate change and seek harmonious development with environment is the primary task of scientists and policy makers; therefore, the research for clean and sustainable energy has seen explosive growth. with the rapid development of solar power, hydro- gen energy, biofuels, etc., breakthrough in generating and storage of energy has driven the industry and technology to a new era. the modern society started to embrace the capti- vating technology of hydrogen vehicle, low energy housing and renewable heat. energy-related topics attract enormous attentions from governments, societies and even investment. to meet the growing demand on sustainable energy resources, scientists all over the world are now making a concerted effort in the innovation of new and advanced tech- nologies, aggressive energy policies, action and planning activities. at the policy level, plenty of policy instruments are used to lead economic activity toward environmental sustainability, such as regulation, subsidies and tax incen- tives. efforts are now putting on to resolve the barriers of commercial production based on sustainable energy and to get out of a predicament of environment and sustainabil- ity. as the main force to promote green energy revolution, researchers from different fields have realized that develop- ing novel and reliable materials and devices is essential to improving the efficiency and safety of new energy as well as reducing environmental impacts. the unremitting efforts of cross-field research works have broadened the academic horizon and brought together chemistry, materials science, applied and theoretical physics, fabricating new materials and designing manufacturing methods or reviving present materials for brand new applications for next-generation energy technology. the transactions of tianjin university (issn - ) is an academic journal published by the springer nature group. the theme of our journal is to publish high-quality, cutting-edge research in natural science and engineering, particularly focusing on energy-related technologies. the journal will serve as a high-quality platform for researchers working in a wide variety of scientific areas with interests in energy-related fields, such as solar energy and photo- voltaics, energy storage and conversion materials, batter- ies and supercapacitors, co conversion and storage, new strategies for the clean utilization of coal and oil and so on. transactions of tianjin university is an international, peer-reviewed, interdisciplinary journal, which publishes a full mix of research article types, including letters, articles, perspectives, reviews and viewpoints with online publica- tions accessed through springerlink (https ://link.sprin ger. com/journ al/ ). the editor in chief of transactions of tianjin univer- sity is prof. jinlong gong, cheung kong chair professor and vice president of tianjin university, who is one of the global highly cited researchers in both and . with a group of experienced scientists teamed up to make sure the high quality of our journal articles, three associate editors are on board, including prof. rafael luque (universidad de córdoba), prof. tierui zhang (technical institute of phys- ics and chemistry, cas) and prof. qiang zhang (tsinghua university). the diversity of insights and expertise of this elite editorial team will present our readers with the most * jinlong gong trans_tju@tju.edu.cn tianjin university, tianjin, china https://link.springer.com/journal/ https://link.springer.com/journal/ http://crossmark.crossref.org/dialog/?doi= . /s - - -z&domain=pdf j. gong insightful and cutting-edge research achievements and pro- vide authors a highly efficient peer review and publishing production processes. we firmly believe that, with all the efforts of our excellent editorial team, critical reviewers, pas- sionate readers and ingenious authors, transactions of tian- jin university will evolve into a leading scientific journal in the research field of green and sustainable energy. jinlong gong editor in chief transactions of tianjin university open access this article is licensed under a creative commons attri- bution . international license, which permits use, sharing, adapta- tion, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the creative commons licence, and indicate if changes were made. the images or other third party material in this article are included in the article’s creative commons licence, unless indicated otherwise in a credit line to the material. if material is not included in the article’s creative commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. to view a copy of this licence, visit http://creat iveco mmons .org/licen ses/by/ . /. jinlong gong studied chemical engineering and received his b.s. and m.s. degrees from tianjin university and his ph.d. degree from the university of texas at austin under the guid- ance of c. b. mullins. after a stint with professor george m. whitesides as a postdoctoral research fellow at harvard uni- versity, he joined the faculty of tianjin university, where he cur- rently holds a cheung kong chair professorship in chemical engineering. he was a visiting scientist at the pacific northwest national laboratory in . he has served on the editorial boards for several journals including chemical society reviews, chemical sci- ence, and aiche journal. he has also served as an associate editor for acs sustainable chemistry & engineering. he is an elected fellow of the royal society of chemistry. he has published more than papers in peer-refereed journals (with citation over times and h-index of ) and been listed as a co-inventor on patents and applications. his research interests in catalysis include catalytic conversions of green energy, novel utilizations of carbon oxides, and synthesis and applica- tions of nanostructured materials. professor gong is the director of the office of academic affairs of tianjin university. http://creativecommons.org/licenses/by/ . / 	transactions of tianjin university: join us to step up to the next generation of sustainable energy optimization of hydrogen distribution network considering pressure and heat recovery - © published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of applied energy innovation institute doi: . /j.egypro. . . energy procedia ( ) – sciencedirect the th international conference on applied energy – icae optimization of hydrogen distribution network considering pressure and heat recovery ruifeng donga, yunsong yub, zaoxiao zhanga,b,* a state key laboratory of multiphase flow in power engineering, xi’an jiaotong university, xi’an , pr china b school of chemical engineering and technology, xi’an jiaotong university, xi’an , pr china abstract hydrogen is an important resource in chemical processes. in the hydrogen network, many units are operating at high temperature and pressure, which leads to a large energy change of hydrogen streams. however, the recovery of heat and work in the hydrogen flows has seldom been studied together with the optimization of hydrogen network. it is obviously that the reuse of heat and work energy will raise the effective utilization rate of energy. the recovery of heat could be realized by heat exchangers. the recovery of work will be realized by rotary work exchangers, which are composed of several compressors and turbines with the same shaft. a state space superstructure is adopted to handle all the variables. the mathematical model is built based on exergoeconomic analysis considering both energy and economic factors. the optimization problem will be a mixed integer nonlinear programming (minlp) problem. the existing algorithms will be improved. a typical refinery hydrogen network is studied as an example. the state space superstructure, exergoeconomic analysis and proposed algorithm could solve the problem competently. the consideration of pressure and heat recovery could reduce the energy consumption and economic cost simultaneously. © the authors. published by elsevier ltd. selection and/or peer-review under responsibility of icae keywords: hydrogen network; heat recovery; work recovery; exergoeconomic analysis; global optimization algorithm . introduction with the rapid development of the world economy and industry, the consumption of fossil fuels is increasing sharply. the utilization of fossil fuels leads to many serious problems, such as energy crisis, greenhouse effect, environmental pollution and so on. as an important chemical material, hydrogen could also be used as an alternative energy source. with the increasing requirement on oil quality and rigorous environmental policies, the refineries should raise the capacity of hydrotreating to cover the increasing * corresponding author. tel.: + - - ; fax: + - - . e-mail address: zhangzx@mail.xjtu.edu.cn available online at www.sciencedirect.com © published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of applied energy innovation institute http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf ruifeng dong et al. / energy procedia ( ) – consumption of hydrogen. therefore, the efficient use of hydrogen and the optimization of hydrogen distribution network are of important significance for refineries. simpson [ ] first addressed the major role of hydrogen management in the design and operational considerations of the refinery in . there are two main methods to optimize the hydrogen distribution network, which are pinch analysis [ ] and mathematical programming method [ ]. the optimization of hydrogen distribution network considering hydrogen compression process has been studied a lot. wu et al. [ ] proposed the exergy objective to express hydrogen consumption and compression power on a common basis. they adjusted the number of compressors manually after the calculation. however, the optimization of compressor positions could also be determined by mathematical programming [ ]. in a refinery, the operating temperature and pressure of hydrogen flows are often very high, which leads to large temperature and pressure differences between the hydrogen sources and hydrogen sinks. therefore, it is important to consider the temperature and pressure of hydrogen flows in the hydrogen distribution network. this paper will focused on the optimization of hydrogen distribution network considering pressure and heat recovery. the superstructure, mathematical model and algorithm will be studied. a case study will be carried out to prove the suitability of the whole optimization procedure. . problem statement the most important basic utilities in refineries are heat, work and hydrogen, which should be optimized simultaneously for a globally optimal solution. a state space superstructure for integrated heat, mass and work exchange network [ ] is adopted in this study. the proposed superstructure by dong et al. [ ] could easily handle all the variables. different from traditional hydrogen distribution network, the heat and work recovery will also be incorporated in the optimization. each hydrogen source with the given flow rate (fi), pressure (pi), temperature (ti) and purity (yi), will be allocated to hydrogen sinks. each hydrogen sink has the limits to inlet purity (yj min), flow rate (yj min), temperature (tj) and pressure (pi). fig. . state space superstructure [ ] the recovery of heat will be realized by heat exchangers, and the recovery of work will be realized by work exchangers. a typical work exchanger contains an electric motor, several compressors and turbines with the same shaft. the work from depressurized hydrogen flows will be transferred to pressurized flows ruifeng dong et al. / energy procedia ( ) – as shaft power. the exergy of hydrogen distribution network will be analyzed. the chemical exergy reveals the flow rate and purity of hydrogen flows, while the physical exergy stands for the temperature and pressure. the exergoeconomic analysis is carried out by considering both exergy and economic costs. the objective will be minimizing the total annual economic cost per unit exergy of hydrogen sinks. the optimization will be a nonconvex mixed integer nonlinear programming (minlp) problem. . mathematical model in the hydrogen distribution network, there are m hydrogen sources and n hydrogen sinks with respective flow rate, purity, temperature and pressure. based on exergoeconomic analysis and the superstructure shown in fig. , mathematical model is developed to solve the problem. according to the exergoeconomic analysis, the objective is to minimize the annualized economic cost per unit exergy of hydrogen sinks (cout). out out inmin min ec c e c ( ) the annualized economic cost c could be calculated by the capital cost ce and operating cost co. e oc c x c ( ) the exergy of hydrogen sink flows eout can be calculated by eq. ( ). out in losse e e ( ) out ine e e ( ) the exergy of hydrogen flow is the summation of chemical exergy and physical exergy. h h hi i ie e h h t s s ( ) in , in in m n i i j i j e e f w q ( ) the exergy loss mainly takes place in the heat and pressure exchange process and mixing process, which is shown in table . the constraint equations of flow rate, purity, temperature and pressure are shown in table . table . constraint equations of exergy loss item constraint equation total exergy loss loss loss,m loss,t loss,pe e e e ( ) exergy loss in mixing process loss,m lnl l l e t s t r n y ( ) exergy loss in heat exchange process loss,t h hm lm e t q t t ( ) exergy loss in pressure exchange process loss,p p p loss h o e w p f ( ) table . constraint equations of hydrogen flows item constraint equation hydrogen source , n i j i j f f ( ) hydrogen sink min , m j i j i f f ( ) purity max, , m m i j i i j j i i f y f y ( ) temperature ,i j jt t ( ) pressure ,i j jp p ( ) the interaction between temperature and pressure of hydrogen flow could be calculated by peng- robinson (pr) equation as eq. ( ) shown. the coefficients could be obtained in the literature [ ]. ruifeng dong et al. / energy procedia ( ) – p rt v b a t v v b b v b ( ) . algorithm there are so many variables in the mathematical model. almost all the variables have interaction between each other, which leads to many bilinear terms. the algorithm, which is efficient to deal with bilinear terms, should be carried out to solve the optimization problem of hydrogen distribution network considering pressure and heat recovery. now the most efficient algorithm to treat bilinear terms is direct partitioning methodology [ ]. the equal section is adopted in the partitioning process. however, golden section could be more efficient than equal section. branch and bound (bb) algorithm is thought to be an efficient way to find out the optimal network structure. therefore, a hybrid parallel algorithm composed by bb algorithm, partitioning methodology and golden section method is proposed in this paper. a case study from literature [ ] is carried out. both partitioning methodologies with equal section and golden section are studied. the result in fig. shows that the partitioning methodology with golden section has a shorter computing time. fig. . computing speed of the algorithms . case study a case study [ ] will be studied to verify the advance of heat and pressure recovery and the performance of proposed algorithm. the basic data of hydrogen distribution network is shown in table . table . hydrogen sources and sinks hydrogen flow flow rate/g·s- purity pressure/mpa temperature °c sources h plant . . . psa . . . ccr . . . hc . . . dht . . . nht . . . sinks hc . . . cnht . . . dht . . . jht . . . is . . . nht . . . the standard chemical exergy of hydrogen is . kj·mol- [ ]. other data are detailedly listed in literature [ ]. the calculation will be carried out by gams software. ruifeng dong et al. / energy procedia ( ) – after calculation, the optimal hydrogen distribution network is shown in fig. . fig. . optimal hydrogen distribution network the minimum economic cost per unit exergy of hydrogen sinks is . $·gj- . hydrogen consumption is . g·s- , which is the same with literatures [ ]. the number of compressors is . however, the compressors cp - , cp - and cp - could be treated as one compressor with intermediate cooling and discharge. the number of compressors from literature [ ] is also , which ignored the detailed intermediate cooling process. other results about energy and economic costs are listed in table . table . energy and economic results item value exergy loss in heat exchange process /kw . exergy loss in pressure exchange process /kw . exergy loss in mixing process /kw . total power consumption /mw . power recovered by turbines /kw . capital cost of compressors /m$ . capital cost of turbines /k$ . capital cost of heat exchangers /k$ . capital cost of pipes /k$ . annualized operating cost /m$ . the recovery of pressure power could reduce . kw of power consumption. the reduction of power consumption could save . k$·y- , while the capital cost of turbines is . k$. therefore, the payback period of turbines is only . years. the application of turbines could easily cut down energy and economic costs at the same time, which should be popularize in refineries. the heat exchangers recover . kw heat energy and reduce the energy consumption as well. ruifeng dong et al. / energy procedia ( ) – . conclusions the optimization of hydrogen distribution network considering pressure and heat recovery is studied in this paper. the optimization problem is solved based on the state space superstructure and exergoeconomic analysis. the algorithm of partitioning methodology is improved by combining with golden section method. a case study from a refinery is studied. the result shows that the consideration of pressure and heat recovery could reduce the energy and economic costs simultaneously. the employment of heat exchangers and rotary work exchangers could reduce the energy consumption greatly. the capital cost of heat exchangers and turbines could easily be paid back by the reduction of operating cost. the exergoeconomic analysis gives out a balanced solution between energy and economic factors, which is a good way for the sustainable development of chemical plants against the background of energy crisis and environment pollution problems. the proposed partitioning methodology with golden section method could solve the problem rapidly and accurately. the consideration of heat and pressure recovery is very necessary for the optimization of hydrogen distribution network in refineries. acknowledgements financial support from national natural science foundation of china (no. ) is greatly acknowledged. references [ ] simpson dm. hydrogen management in a synthetic crude refinery. int j hydrogen energy ; : - . [ ] towler gp. integrated process design for improved energy efficiency. renew energy ; : - . [ ] hallale n, liu f. refinery hydrogen management for clean fuels production. adv environ res ; : - . [ ] wu s, yu z, feng x, liu g, deng c, chu kh. optimization of refinery hydrogen distribution systems considering the number of compressors. energy ; : - . [ ] kumar a, gautami g, khanam s. hydrogen distribution in the refinery using mathematical modeling. energy ; : - . [ ] dong r, yu y, zhang z. simultaneous optimization of integrated heat, mass and pressure exchange network using exergoeconomic method. appl energy ; doi: . /j.apenergy. . . [ ] mathias pm, copeman tw. extension of the peng-robinson equation of state to complex mixtures: evaluation of the various forms of the local composition concept. fluid phase equilibr ; : - . [ ] faria dc, bagajewicz mj. a new approach for global optimization of a class of minlp problems with applications to water management and pooling problems. aiche j ; : - . [ ] hallale n, liu f. refinery hydrogen management for clean fuels production. adv environ res ; : - . [ ] morris dr, szargut j. standard chemical exergy of some elements and compounds on the planet earth. energy ; : - . biography professor zaoxiao zhang works in the school of chemical engineering and technology, xi’an jiaotong university. the research areas are focused on co capture and sequestration technologies, energy storage and utilization, and new type of chemical machinery. proceedings , , ; doi: . /proceedings www.mdpi.com/journal/proceedings proceedings adapting to engineering education vision † musarat yasmin ,*, farhat naseem and malik hassan raza department of english, university of gujrat, hafiz hayat, gujrat , pakistan; malik.hassan@uog.edu.pk munk school of global affairs & public policy, university of toronto, toronto, on m s a , canada; farhat.naseem@utoronto.ca * correspondence: musarat.yasmin@uog.edu.pk; tel.: + - - - † presented at the nd innovative and creative education and teaching international conference (icetic ), badajoz, spain, – june . published: october abstract: interdisciplinary energy research has become inevitable in the context of perceived energy break-point after . power and energy crisis is a matter of life or death for industry and human race on earth. oil and natural gas peaking alarms started ringing by the start of the st century. available energy reserves are emptying at of thousands of barrels per second and time to discover new energy sources is being wasted to convince and advocate disciplinarians going for interdisciplinary research approach. we will have to invent new ways of supplying % of the global energy demand by and % by . it is not possible without putting the emerging bio, nano, and info technologies together in power and energy research laboratories under interdisciplinary and trans-disciplinary approaches. electrical engineers badly need the supportive hand of energy scientists and technologists to overcome global power, energy, food, and water crises. engineers and scientists often find it difficult to tolerate each other and usually end up with duplicate resources without any presentable output which requires motivation to develop teamwork spirit to succeed. this paper unveils the potential urgency for an interdisciplinary research approach concerning embedded energy research barriers and solutions in developing countries. enhancing power and energy multidisciplinary research is a vital general formula that can be tailored to specific regional conditions to minimize the greenhorn blues to run local and global interdisciplinary research programs. keywords: trans/multi/interdisciplinary; climate change; global warming; energy crisis . engineering education practices engineering education practices, in the public sector as well as private universities, in pursuance of their business are seriously violating engineering education ethics in pakistan. apprehensively, i am daring to collect my courage in the best interest of the nation to point out some serious flaws and perilous anomalies in ongoing engineering education practices merely to warn the engineering education managers and regulatory bodies, i.e., pakistan engineering council (pec) and higher education commission (hec) to take timely actions. buzz terms have replaced the bona fide hardware based engineering education with simple wordy soft skills instead of the professional skills desired to our engineering industries. competent engineering education and research regulatory bodies like pec and hec need more powers like the abet in the usa and feani in europe [ ] to monitor institutional compliance to engineering education requirements at admission, learning and examining levels in undergraduate degree awarding programs and quality research at postgraduate levels in pakistan. engineering education managers have recently realized that their be telecom, computer, and electronics engineering degrees have no acceptance in the electrical industry as % employers want electrical engineers, not telecom, robotic and computer engineers. two decades ago proceedings , , of the emergence of the internet and mobile telecom industry created a boom for telecom engineers, but it has now got saturated. . a mandate to nowhere disciplinary education and research systems have failed to keep up with nature due to their narrow spectrum of interests ignoring frontiers of research bridging the major disciplines. this drawback has led to new concepts of multidisciplinary, interdisciplinary and trans-disciplinary research approaches to address the issues. nature is continuous like the land and sea it is we who have divided it into countries and subcontinents. disciplinarians usually like to stay isolated, but solutions to many complex problems (like climate change and energy crisis) require the input of multiple disciplines. establishment of interdisciplinary research centers can foster research on blind corners hidden among significant science and engineering disciplines [ ]. . interdisciplinary energy research new science and engineering frontiers are neither covered under disciplines nor there exist interdisciplinary programs. the lines distinguishing one speciality area from another is almost indistinguishable. research student’s interests are broader than traditional areas within the disciplines. students interested in energy in chemistry go for fuel cells, blue energy membrane design and students interested in energy in physics go for solar cells and students in biochemistry go for photosynthesis and biofuels. significant disciplines usually do not have enough subject specialists to accommodate limited student’s interests. some universities (like university of minnesota) have started interdisciplinary degree programs to support specific students in their particular research interests in renewable energy, molecular electronics, polymer solar cells, solar paints and photochemistry. recent oil and gas peaking scenario have severely affected youngster mind and their major interests have focused on energy thrust areas that may include but not limited to long life dc batteries, co sequestration, carbon capture, super capacitors, anti-greenhouse effect, photosynthesis engineering, fuel cells, fuel cell membranes, osmotic power plants, biofuels, hydrogen storage, and future energy sources. for instance, fiber optic voltage and current sensors, ssr, fuel cells, telemetry, earthquake forecasting, lithospheric architecture and dynamics, quantum wires, dots, single photon lasers and detectors are not covered in any single discipline [ – ]. a straightforward way is to start bs/ms/phd degree programs by research under the supervision of a committee for each student according to his specific research interests. trying to force camel and ant to pass through the same pipe is useless where students study subjects merely to earn credits that do not contribute to their research interests. more than % of universities do not have trained workforce under any discipline to deal with all above new energy research frontiers. there is no way to go ahead except opting interdisciplinary and transdisciplinary degree programs or research approach to guide students to explore new energy sources in the air, sea and elsewhere [ ]. international universities and research institutes have already felt the never-ending complexity of energy issue and started interdisciplinary education and research programs to mitigate energy shortage global insecurity. universities that have begun interdisciplinary or multidisciplinary energy research programs may include but not limited to penn state university, imperial college, rensselaer, university of canterbury, and university of leads etc. according to energy research magazine report, multiple universities have either started energy education and research programs or are in the phase of multidisciplinary to interdisciplinary transition. research centers that have started multidisciplinary research include but not limited to the center for energy and the global environment (ceage), the virginia center for coal and energy research (vccer), the center for energy systems research (cesr), the center for power electronics (cpe), and the macromolecules and interfaces institute (mii) etc. future energy supply to society is a big challenge that individual disciplines cannot harness alone without developing a spirit of interdisciplinary research and development. keeping in view world energy sources and global power needs [ ] we must readjust our energy wasting attitudes and prepare our generations to cope with future power and energy crisis. our forefathers and we have enjoyed the best possible time on earth. we have cars, aero planes and bullet trains to travel but our proceedings , , of dearest children might not have accessed to all these facilities when they grow to our age after years. ksa is considered as the most significant oil player, but she has only billion barrels reserves ( % from only ghawar) which at a rate of . billion barrels per year (@ million barrels per day) can run for years. canada has billion barrels reserve but cannot extract more than million barrels per day (one-third of ksa). alone us oil consumption is million barrels per day. to produce barrel crude oil from tar sands, it produces tons of dirty sands emitting strange gases to pollute the environment. public strikes are likely to start at $/barrel oil prices without government subsidies. we must think of reducing reliance on oil not only due to high prices and shortages but also due to global warming of the planet. fossils fuels combustion triggered greenhouse effect is absolutely responsible for rising temperatures [ ]. power, energy, food, and water shortages are the direct effects but possibilities of floods, cyclones, diseases, dirty environment and extinction of many known organisms may also be the ultimate consequences of increasing the heat on earth’s surface [ , , – ]. we are cooling our cars and home at expense of heating the planet without imagining the horrible consequences reported by hundreds of the most trusted and reliable researchers. the evil axis of shortages of energy, power and food chains would trigger multiple unexpected events followed by fuel and survival wars reddening the surface of planet earth. due to food shortages, lawlessness starts that leads to street crimes and insecurity [ ]. to defend at own the people have already started catching robbers to burn them alive instead of handing over to police or courts from fear of injustice. it is happening due to high prices and food crisis. similar blood for oil politics will cause widespread wars. of course, the global brain has awakened to avert large-scale human bloodshed but professionals who cannot contribute any idea should at least not create problems for others to run renewable energy programs. many problems can be solved using appropriate engineering tools [ , ], and even if the technology fails at the moment, there is no way out except rethinking again and again. to search more novel techniques, we have to keep an eye on how the inventions take place and how the innovatory works were reported in past. energy issue cannot be solved emotionally (individually) instead it needs collective (interdisciplinary) efforts from all branches of science and engineering. whatsoever, it is the primary headache of the electrical power, chemical, and biochemical engineers how to improve design efficiency for energy conservation, synthesize organic molecules for petroleum like energy and electrons for the dc/ac electricity. all applied science and engineering branches can effectively contribute through interdisciplinary education and research [ ]. chemists and chemical engineers can function better for fuel cells, biochemists and chemical engineers can better perform on bio-fuels, geophysicists, mechanical and electrical engineers can better deliver on ocean power plants, physicists, chemists and electronics engineers can prove better on solar cells, environmentalists, electrical, and mechanical engineers. . conclusions scientists and engineers in the developing countries are stuck in the mud of disciplines defense politics which is seriously affecting the interdisciplinary research efforts. energy avenues are located in frontiers belts among various significant disciplines. oil and gas peaking scenarios have shaken all communities in east and west except researchers of developing countries who are lagging behind the international community due to their non-technical reasons. global warming, power, energy, food and water crises are headlines of electronic and print media. public is frightened of horrible future without energy and food. we are in transition process from oil or gas to new unexplored energy sources. there is no clear new energy source capable of handling current global energy demand after oil and gas. coal is a potential option, but it would further strengthen the global warming that is already difficult to tolerate. potential avenues may be located among various major disciplines. electrical engineers bearing telecom degrees oppose renewable energy research and studies due to their reasons. developing countries need urgently to move towards interdisciplinary research among universities to make good use of the available manpower to explore new energy sources to join the international race on before we cross the rubicon defining dead end borders. proceedings , , of references . pec. pakistan engineering council . available online: http://www.pec.org.pk/ (accessed on september ). . heitkemper, m.; mcgrath, b.; killien, m.; jarrett, m.; landis, c.; lentz, m.; woods, n.; hayward, k. the role of centers in fostering interdisciplinary research. nurs. outlook , , – .e , doi: . /j.outlook. . . . . khan, n.; goldwasser, s.m.; abas, n.; kalair, a.r.; haider, a. experimental investigation of unidentified helium–neon lasers. appl. opt. , , doi: . /ao. . . . abas, n.; kalair, a.; khan, n.; kalair, a.r. review of ghg emissions in pakistan compared to saarc countries. renew. sustain. energy rev. , , – , doi: . /j.rser. . . . . khan, n.; abas, n.; kalair, r. electronic and photonic communiqué bottlenecks mandate ultrafast optics. nonlinear opt. quantum opt. , , – . . khan, n.; kalair, a.; abas, n.; haider, a. review of ocean tidal, wave and thermal energy technologies. renew. sustain. energy rev. , doi: . /j.rser. . . . . abas, n.; kalair, a.; khan, n. review of fossil fuels and future energy technologies. futures , , – , doi: . /j.futures. . . . . abas, n.; kalair, a.r.; khan, n.; haider, a.; saleem, z.; saleem, m.s. natural and synthetic refrigerants, global warming: a review. renew. sustain. energy rev. , , doi: . /j.rser. . . . . kalair, a.; abas, n.; khan, n. high repetition rate dfb laser for broadband networks. nonlinear opt. quantum opt. , , – . . abas, n.; khan, n.; haider, a.; saleem, m.s.; kalair, a.r. co utilization drivers, opportunities and conversion challenges. ref. modul. mater. sci. mater. eng. , doi: . /b - - - - . - . . khan, n.; kalair, e.; abas, n.; kalair, a.r.; kalair, a. energy transition from molecules to atoms and photons. eng. sci. technol. int. j. , doi: . /j.jestch. . . . . abas, n.; khan, n.; haider, a.; saleem, m.s. a thermosyphon solar water heating system for sub zero temperature areas. cold reg. sci. technol. , , – , doi: . /j.coldregions. . . . . khan, n.; abas, n. smart crime science and shabby control technologies. vfast trans. educ. soc. sci. , , – . . khan, n.; abas, n.; kalair, a. design of an optical clock repetition rate multiplier. nonlinear opt. quantum opt. , , – . . khan, n.; abas, n.; kalair, a. multiline distributed feedback dye laser endorses wien’s displacement law. appl. phys. , , , doi: . /s - - - . . yasmin, m.; sarkar, m.; sohail, a. exploring english language needs in the hotel industry in pakistan: an evaluation of existing teaching material. j. hosp. tour. educ. , , – , doi: . / . . . © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). microsoft word - final-waset-rtc - -  abstract—tidal power can play a vital role in integrating as new source of renewable energy to the off-grid power connection in isolated areas, namely sandwip, in bangladesh. it can reduce the present energy crisis and improve the social, environmental and economic perspective of bangladesh. tidal energy is becoming popular around the world due to its own facilities. the development of any country largely depends on energy sector improvement. lack of energy sector is because of hampering progress of any country development, and the energy sector will be stable by only depend on sustainable energy sources. renewable energy having environmental friendly is the only sustainable solution of secure energy system. bangladesh has a huge potential of tidal power at different locations, but effective measures on this issue have not been considered sincerely. this paper summarizes the current energy scenario, and bangladesh can produce power approximately . mw across the country to reduce the growing energy demand utilizing tidal energy as well as it is shown that sandwip is highly potential place to produce tidal power, which is estimated approximately . mw by investing only us $ . million. besides this, cost management for tidal power plant has been also discussed. keywords—sustainable energy, tidal power, cost analysis, power demand, gas crisis. i. introduction enewable energy provides secure energy for any country to develop its infrastructural, socio-economic, agricultural, educational, health and community sector in stable condition. renewable energy means sustainable energy which is environment friendly, cost effective, non-polluting and future predicted energy sources. that is why developed countries are shifting their energy sector toward sustainable energy to maintenance their continuous growth. tidal is one of the sustainable energy sources and have huge potential to produce power from its energy [ ]. many countries are taking advantage from tidal energy to produce power for successfully transferring the energy sector into sustainable energy. bangladesh has also opportunity; sandwip is one of them, to use its facilities in various locations observing in proper way and guidance. it is mandatory to develop the energy sector before developing a country, in this regard tidal energy in sandwip can play a vital role to improve its locality with integrating development of country [ ]. sandwip project will be slightly helpful to mitigate the present energy crisis and shifting energy sector toward sustainable energy sources. this paper is mainly divided into four parts . energy sector md. alamgir hossain, md. zakir hossain and md. atiqur rahman are with the department of electrical & electronic engineering, dhaka university of engineering & technology, gazipur, bangladesh (corresponding e-mail: alamgir_duet@hotmail.com). condition and shifting . tidal power . feasibility study of sandwip, and . data analysis. ii. energy sector condition and shifting bangladesh, only % people are in grid connected [ ], is one of the lowest electricity consumptive country regionally and globally [ ]. the existing power system cannot produce sufficient power for the whole nation. scarcity of power is a principal infrastructural handicap in the development and growth of any country [ ]. the growth of the energy sector in bangladesh is not sufficient to meet the power demand, which is increasing by % annually [ ]. electricity supply in the rural and remote areas has been restricted due to transmission losses, high transmission costs, distribution costs, and greatly subsidized prices. growing population and financial activities drive the country toward high electricity demand. the shortage of electricity was mw to meet the high demand in , though the maximum electricity generation was , mw. according to [ ], in , the shortage of gas supply hinders the electricity generation around - mw. a. gas dependent power generation at present, power plant generates power utilizing . % of our gas reserve [ ], which is % of total gas, but consumption of gas demand increase at rate about % per year [ ]. however, at the present consumption rate of gas reserve leads it up to year [ ], whereas net remaining recoverable gas was . tcf at the end of . fig. shows the percentage of installed generation ( mw) capacity in bangladesh from various sources in . fig. the percentage of electricity generation in bangladesh from different sources [ ] and [ ] it is seen that from fig. , gas dependent power plant was installed . % of total installed capacity, but in actual case, some of other fuel dependent plants were abandoned, so total perspective and challenge of tidal power in bangladesh r md. alamgir hossain, md. zakir hossain, md. atiqur rahman world academy of science, engineering and technology international journal of energy and power engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e ne rg y an d p ow er e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/perspective-and-challenge-of-tidal-power-in-bangladesh/ http://scholar.waset.org/ - / power generation was more depend on gas than the scenario. sustainable energy sources use only . % of electricity production. fossil fuel use . % of total generation which is polluting the air, land, and water and emitting co . these pollution and emanation guide to environmental dilapidation which results bigger climate hazard and natural disasters. b. power generation planning power demand is increasing higher and becoming more as years go further, but growing high nature demand is going to be encountered by vulnerable energy source plan [ ], though recently need for power is being met by quick-rental power plants which require costly liquid fuels. to meet the next power demand, power development of bangladesh proposed roadmap for "the power system master plan ( )" recommending that the % of power generation would be coal-based but this planning is not environmentally friendly, security energy planning, rather it helps in the increasing global warming through breathing co . our total coal reserves are , million tons according to bangladesh's national energy policy . c. towards sustainable energy as fossil fuels are depleting at a higher rate, so we have to think to other sources mainly renewable. the country is going to be facing a severe energy crisis after the fossil fuel finish. so, country has no energy security in this respect. thus, sustainable energy is the only solution to get rid of this problem; which is becoming more acute as years proceed. to proceed fully toward renewable energy sources require some time, so in between these transaction periods fossil fuel can play a vital role. toward the moving secured and sustainable energy sources, tidal power can assist to play a role in this regard. iii. tidal power commercial ocean energy capacity (most tidal power facilities) remained at about mw at year's end, with little added in [ ]. the world's first and second large-scale tidal power plant, the rance tidal power station located at the estuary of the rance river, operated in is megawatts, which is generated by its turbines. it supplies . % of the total power demand of france [ ]. the world's biggest tidal power station operated by the korean water resource corporation in having total output capacity mw with mean operating tidal range . m is situated at sihwa lake tidal power station. total cost for this project was . million dollars met by the south korean government [ ]. incheon tidal power station which is under construction, another large tidal power station, is expected x = mw generating capacity at the incheon bay in south korea. total development and construction cost are hoping to reach us $ . billion with completion in june [ ]. a. bangladesh perspective bangladesh, electricity consumption per capita is only kwhr which is much less than any developed country [ ], has an extended costal area with - m tidal height ascend and descend [ ]. this height is adequate enough to generate power. tidal energy can be simply generated from the varying sea levels, and tides are more foreseeable than wind and sunlight. tidal currents can be precisely anticipated within % accuracy decades into the future [ ]. changing tidal can be used to produce electricity across a coastal bay with huge differences between low and high tides. electricity generation from tides is very analogous to hydroelectricity generation apart from that water; which is able to run in both directions, and electricity is produced using two-way turbines. the technology used in tidal power is very simple and has a probable life of more than years [ ]. b. advantage production of electricity from tidal is hours a day and days a year and has a highly efficiency ( %) competitive with other power sources. costal people can irrigate and make their life more solvent economically than before by means of tidal power. a set up expenditure to build a tidal energy plant is high, but the repairing costs are very low. the price of electricity has been paid off in or years after the capital costs and can be assumed to be almost zero. so, profit can be earned using tidal power technology [ ]. iv. feasibility study of sandwip sandwip, the eastern side of the delta region, is most approving locations for tidal power application. a flood control barrier exists around the entire island, and this contains sluice gates. these barrages and sluice gates can be used for electricity generation. therefore, the potential of tidal power is very accessible to be applied because the barrages are essential for controlling flow through turbines, which is also essential for controlling flood. this invalidates high capital cost for the engineering is already there or is crucial for cyclone protection. the energy available from a barrage is dependent on the volume of water. the potential energy contained in a volume of water is [ ], e= gha ( ) where, a = area of basin (m ) ρ = water density (kg/m ) g = acceleration due to the earth's gravity, and h = tidal range (m) output power, p = (energy (e) x turbine efficiency)/ (w) ( ) power generation from tidal can be computed using ( ). world academy of science, engineering and technology international journal of energy and power engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e ne rg y an d p ow er e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/perspective-and-challenge-of-tidal-power-in-bangladesh/ http://scholar.waset.org/ - / fig. sky scenario of sandwip from google map [ ] a rough estimate of investment and power production by tidal power in sandwip are shown below. fig. flow chart of estimated cost of sandwip project a. cost management and estimating economic support can be obtained from different sources of financial institutions, those help to develop sustainable energy system such as world bank climate investment, the adaptation and the least developed countries funds [ ]. moreover, clean development mechanism and carbon finance, internationally recognized mechanisms, give the opportunity to make funds for installing any sustainable project to develop a nation. the main aims of above mentioned organizations are to reduce gas emission and vulnerable situation for the adverse effect of climate change promoting green energy technology and sustainable developing the poorer communities of the developing world [ ]-[ ]. since, bangladesh is a most vulnerable country selected in cop conference and developing, which is suffering most for the climate change. so, tidal power project in sandwip will be positive for this country and getting available financial support from all the above cited organization. sandwip project is mainly divided into categories.  executable study: executable study involved in the proper location selection, land rights, environmental judgment, interconnection energy accord, system modeling, preliminary designs (electrical, mechanical and civil) and complete expenditure list. to do this study, approximately us $ need.  processing: it includes engaging managers, engineers, and laborers allowing sufficiency food, accommodation, and so on. besides, from the executable study outcome; different tendering process will be approaching, selecting, evaluating and supervising the whole activities worth is us $ .  constructional works: it is mainly divided into two parts a) civil works: this includes access roads, basin installation, power house establishment, and location setting. b) electrical and mechanical works: these include establishing essential equipment such as protection systems, turbines, generators, transmission lines, communication lines, controlling, monitoring and so forth. the total cost for these works is us $ and finally  operation and maintenance: these provide for the total project considering administrative costs like leases, remunerations, fees, etc. the nearly value of operating and maintenance is us $ . so, total cost need to implement and operate a tidal power base sustainable energy is around us $ . million. table i summarized of sandwip project parameter value tidal range . m no. of sluice gates no. of turbine uses basin area x m construction time years cost us $ . millions output power . mw v. data analysis sandwip has a great potential to produce power from tidal is around . mw, which is quite helpful to shrink power crisis through sustainable energy in bangladesh by investing only us $ . million. nonetheless, other parts of the country can produce energy around . mw from different tidal ranges [ ] considering basin area x m [ ], which is shown below. executable study (designing & modeling) $ processing (tendering & supervision) $ constructional works operating & maintenance $ civil $ electrical & mechanical $ sandwip project $ , world academy of science, engineering and technology international journal of energy and power engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e ne rg y an d p ow er e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/perspective-and-challenge-of-tidal-power-in-bangladesh/ http://scholar.waset.org/ - / table ii estimated power generation from different location of bangladesh name of the station mean tidal range (m) output power (mw) sandwip . . sadarghat (cht) . . mongla . . char changa . . cox’s bazar . . teknaf . . hiron point . . total . vi. conclusion with the increasing power demand in bangladesh, there is no substantial plan to meet the upcoming power crisis by renewable energy. the country has a great challenge in the upcoming days due to unsustainable dependent energy sources. in this respect, tidal power, as a renewable source of energy with numerous profits, can be a prime supplier for our future energy necessities increasing local hydroponic management with sandwip's socio-economic improvement. in our analysis it is found that bangladesh has immense potential of renewable energy sources like tidal power; which can add at least . mw power in sandwip area giving a solvent economic, social, and psychological improvement in this regional person. moreover, tidal power can generate total . mw from different places of the country, but still now no effective effort can be seen to produce power from this source. references [ ] lingchuan mei. overview of ocean wave and tidal energy. . available at: http://www.ee.columbia.edu/~lavaei/projects/lm.pdf. [ ] solomon d.j. fish passage through tidal energy barrages. energy technology support unit, harwell, contractor's report no" etsu tid , . . [ ] renewable global status report , ren , renewable energy policy network for st century. available at http: // www.ren .net/gsr. [ ] amit s. hq. bangladesh growth report . feb. [ ] mondol a. h. implications of renewable energy technologies in the bangladesh power sector: long term planning strategies. doctoral dissertation, rheinischen friedrich-wilhelms- universitat, . [ ] hossain m. a., ahmed m. r. present energy scenario and potentiality of wind energy in bangladesh. world academy of science, engineering and technology. ; ( ): - . [ ] bangladesh power development board (bpdb), january . http://www.bpdb.gov.bd/bpdb/. [ ] khatun f. cpd-cmi research colloquium. fdi in the energy and power sector in bangladesh: revisiting policies and contribution, dhaka: march . [ ] bangladesh power development board ( ) and *outline perspective plan of bangladesh l - ( ). http://www.bpdb.gov.bd/bpdb/. [ ] ltd., (nova scotia) ieee standard. - -recommended practices and requirements for harmonic control in electrical power systems. the institute of electrical and electronics engineers, pp: - , . [ ] the green optimistic. world's biggest tidal power plant opened in south korea. available at: http://www.gieenoptimis tic.com// l/ korea-biggest-tidal-power-plant/. [ ] the korea times. incheon to house largest tidal power plant. available at:http ://www.koreatimes.co.kr/www/news/biz/ / / l _. l html. [ ] hasan m. r., razan m. j. i., shahriar m. s., islam r. s., s. m. ferdous. nuclear power-an inevitable option for most vulnerable countries from the perspective of environmental degradation. journal of selected areas in renewable energy. in press. [ ] bangladesh tide tables, department of hydrography, bangladesh inland water transport authority of dhaka, bangladesh, . [ ] elghali s.e. ben, benbouzid m.e.h., charpentier j.f. marine tidal current electric power generation technology: state of the art and current status. electric machines & drives conference, iemdc ' . ieee international, ; : - . [ ] fraenkel p.l. tidal current energy technologies. ibis, ; : - . [ ] google maps, available at: https://maps.google.com.bd/maps?q:sandwip% bangladesh. [ ] bryans a.g., fox b., crossley p.a., o'malley m. impact of tidal generation on power system operation in ireland. ieee transactions on power systems, ; - . [ ] nassiry d., wheeler d. a green venture fund to finance clean technology for developing countries. center for global development working, ; - . [ ] subbarao s., lloyd b. can the clean development mechanism (cdm) deliver? energy policy, ; ( ): - . 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[ ] tidal energy and its prospect in bangladesh. a thesis supervised by dr. farseem mannan mohammedy, dept. of electrical and electronic engineering (eee), bangladesh university of engineering and technology (buet). world academy of science, engineering and technology international journal of energy and power engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e ne rg y an d p ow er e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/perspective-and-challenge-of-tidal-power-in-bangladesh/ http://scholar.waset.org/ - / . .j.ijrse. . international journal of sustainable and green energy ; ( ): - http://www.sciencepublishinggroup.com/j/ijsge doi: . /j.ijrse. . issn: - (print); issn: - (online) influence of the incident solar flux on the temperature variation of the hot-box cooker souleyemane thiam , , * , serigne thiao , , awa marr , , issakha youm , center of studies and research on renewable energies (cerer), dakar, senegal department of physics, faculty of sciences and technology, university cheikh anta diop (ucad), dakar, senegal email address: * corresponding author to cite this article: souleyemane thiam, serigne thiao, awa marr, issakha youm. influence of the incident solar flux on the temperature variation of the hot-box cooker. international journal of sustainable and green energy. vol. , no. , , pp. - . doi: . /j.ijrse. . received: july , ; accepted: july , ; published: september , abstract: in rural areas, families do not often have access to butane gas and women are looking for wood to cook. forests are often threatened by the production of charcoal. housewives are exposed to the emissions of these fuels. thus a problem of public health arises. the aim of our work is a part of the development and popularization of solar cooking as an alternative to the abusive use of fossil fuels. on the other hand, it allows to protect the environment and contributes to improving the living conditions of housewives. a prototype was developed at the center of studies and researches on renewable energies (cerer) in dakar, senegal. this is a solar cooker box double glazed and inclined lateral faces, provided with a flat reflector. in this paper we present the results of testing of the prototype. the climatic data in this study are obtained at the cerer weather station. several series of tests were carried out under natural sunlight. they concern empty tests of the cooker and tests of water boiling and cooking. during these tests the temperatures at different points of the cooker were measured at different sunshine and at different times of the year. the results obtained by different tests are satisfactory and encouraging especially as solar cookers are easy to build and test prototype gets to reach temperatures favorable for healthy cooking different food products and dishes. keywords: experimentation, collector, reflectors shots, solar cooker, stove, side panels inclined . introduction successive energy crises in the world have led people to reflect on the fate of man without the fossil energy resources (oil, gas, coal, etc.) that are becoming increasingly scarce as energy demand grow. developing countries are the first to be affected by these multiple crises. since the s, senegal is facing an energy crisis that never ends [ ]. companies are often confronted with fluctuations in the price of oil, fuel shortages, and shortfalls in production, distribution problems and control of the electrical network (senelec) causing cuts and load shedding. at the same time people are facing shortages of butane gas resulting from increases in the price of wood and charcoal... the impact of this crisis has very important consequences for the economy (agriculture, industry, smes, domestic electrification,...) these crises have resulted in extremely high cost of living, paralysis of the economic system but also to advancement of rural deforestation. this leads to increasing desertification, also a degradation of the environment: change of climate, soil erosion, floods in the cities causing displacements of populations by the public services is the case of the diakhaye plan in and noflaye in where whole districts are lost in the waters.... [ ] in some remote areas, the fouta in north, often desert where wood is somewhat rare, the use of cow dung for cooking is the main source of sickness for housewives because they contain harmful gases (methane, co ,...). moreover, due to the scarcity of fossil resources, most of the population's survival strategies are based on natural resources such as the wood of a few rare shrubs, leading to an alarming state of environmental degradation. the sunlight is a natural source of energy, free and inexhaustible [ ]. although unknown to most people, solar cooking is one of the simplest domestic uses of solar energy [ ]. this application is one that can be an alternative to limit deforestation and misuse of fossil fuels whose emissions of greenhouse gases could jeopardize the future of humanity. souleyemane thiam et al.: influence of the incident solar flux on the temperature variation of the hot-box cooker indeed, for citizens living in several remote areas, cooking food is very costly when using conventional energy sources and causing disastrous consequences on the ecosystem. the first solar cooker called "hot box" was invented by horace de saussure, a swiss naturalist who already experimented in . however, solar cooking actually appeared in the s in a context of profound energy crisis [ ]. the solar cooker is a device for cooking food directly through sunlight converted into heat. it achieves average temperatures to cook, boil, and roast. almost everything that could be done with other traditional methods of cooking (wood, coal, electricity, gas...). our work of evaluating the performance of the hot-box solar cooker is part of the development and popularization of this application that is solar cooking. indeed a prototype has been realized, it is a solar cooker of the box type with lateral inclined faces. our objective is to study its use in the climatic conditions of senegal and possibly to make improvements. after a complete description of our cooker, we will undertake a study theoretical study of our system before starting the experimental study which passes through various tests carried out at the center of study and research on renewable energies (cerer). in this document, we present the results obtained from the experimentation of this prototype. several series of tests were carried out under natural sunlight. they involve empty tests of the cooker and of the boiling and cooking tests. during these tests the temperatures at different points of the cooker were measured at different sunshine and at different times of the year. the results obtained by the various tests are satisfactory and encouraging, especially since solar cookers are simple to build and the prototype tested reaches temperatures favorable to the healthy cooking of various food products and dishes. the average temperatures reached allow us to cook, boil, almost anything we could do with other traditional cooking methods (wood, coal, electricity, gas...). . description and modeling the studied system is a solar cooker box with a flat reflector [ ]. it is a wooden box (cons-plated) thermally insulated (glass wool between the inner and outer boxes) and closed by a double glazing (two panes of mm thick, spaced mm from each another) inclined at an angle of ° south relative to the horizontal. this inclination allows the cooker to receive the maximum of radiation because solar oven only works with direct radiation so it is necessary to orient the solar oven correctly in relation to the sun figure . solar cooker hot-box inclined lateral faces. its lateral faces are covered with mirrors and arranged as follows: the north faces, south and east are inclined at an angle of ° relative to the vertical. this allows us to reduce the shadows cast by these faces on the absorber at sunrise. the west side is inclined at an angle of ° to the vertical in order to increase the daily cooking periods without shading the absorber. these faces are lined with flat mirrors to favor the reflection of the rays in the cooker enclosure. the inside bottom is covered with a painted black aluminum plate that serves as an absorber. it converts light energy into thermal energy. a wooden door is opened on the north side of the cooker. it is covered with mirror to reflect radiation on the absorber. it is such a medium sized pot to pass through. to avoid as much heat as possible, avoid opening the oven too much during cooking! the best is still to put all the necessary ingredients from the beginning. figure . diagram of hot-box cooker. the reflector, north opening is made against-plated wood supported by thin tassets. reflection is ensured by aluminum paper lining the surface of the reflector. it serves cooker cover after hours of use. . . theoretical study a solar cooker is a cooking appliance based on the conversion into heat of the light radiation emitted by the sun. international journal of sustainable and green energy ; ( ): - it is a complex energy system where most of the modes of heat transfer are involved. it has several types of solar cookers all operating according to the principle of conversion of light energy into thermal energy. however there are different processing methods of that energy that characterize each cooker. a solar cooker is a box receiving cash from sunlight. it allows cooking food at temperatures from to °c. the infrared rays from the sun are trapped in the cooker with the glass which causes a sharp rise in temperature within the box by greenhouse effect. the system that generates heat energy in some stores and in exchange with the other with its environment, (which we translate by equation ( )) provides thermal balance equations on the various oven components systems [ , ]. ���������	 �����
�� � �����	
�� ( ) figure . total energy exchanges within the cooker. . . heat balance equation equation on the external glass: the heat balance of external and internal glass are given respectively by equations and . ����	����� ����� �� ��������� �! " ����# ���������$%& " ����# � ��'(������� " �� '# � �),� '+���������� " �� '#	 ( ) �� '��� ' ,-./ , ����� '�� � �),$&+� '����� ' " �$&# � �),� '+���������� " �� '# � ��' ����� ' " �$�# � ��'(������� " �� '#	 ( ) the energy balance of the air cooker and the absorber are given respectively by equations and . �$���$ ) ,- , ��' ����$& " �$�# � ��' ����� ' " �$�# ( ) �$&��$& ,- , � �$&�$& � � :%�$& � �),$&+� '�$&��� ' " �$&# � ��' ����$� " �$&# � �$&+ ;��$%& " �$&#	 ( ) . . experimental study the experimental study concerns the performance testing under natural sunlight at the cerer in different periods of the year. for each of these tests measuring the global radiation there are: the average wind speed, ambient temperature, the temperature at the absorbing plate, the outer pane, the inner pane, of the atmosphere of the cooker. in the case of cooking or boiling tests, it also measures the temperature of the kitchen appliance and the temperature of the water to boil. the equipment used to study the cooker consists essentially of kitchen utensils and measuring instruments. as kitchen utensils we used aluminum cooking pots painted in black paste (on the external side only). shorter cooking times are achieved with thin-walled aluminum cooking pots, distributing the food on several cooking pots and kitchen gloves. the measuring instruments consist of: - a pyranometer (kipp & zonen model cm ) which measures the solar flux (global) on a flat surface from a solid angle of °. - platinum resistance thermometers to measure the absorber temperature and the surface of the inner glass. - a probe (+ °c) to measure the ambient air temperature of the cooker. - a laser camera thermometer that measures surface temperatures. thanks to the latter we can measure the temperatures of all external surfaces. - mercury thermometers to measure the temperatures in volume (boiling water...) - a digital anemometer that instantly gives the speed and the orientation of the wind at the site but also the ambient temperature. - a multimeter for measurements of current, voltage, resistances... . . . stagnation tests during these tests, the cooker is sun-exposed without charge: one tests the vacuum cooker performance [ , and ]. . . . tests with load this water heating ranges from to boiling tests and to preparation of some local dishes [ ]. . results and discussion several series of tests were carried out at different insolation. to study the performance of the hot-box cooker, we will exploit the thermal capacity of the cooker during the sunniest periods but also those of lower sun exposure. . . stagnation tests the hot-box exposed to the sun without load; we make a souleyemane thiam et al.: influence of the incident solar flux on the temperature variation of the hot-box cooker vacuum performance test. figure . influence of the incident flux on the temperature variation during / / . these tests were carried out during the day of monday, january , . the day was very sunny; the solar flux exceeds w / m² to . there is also a lack of wind [ ]. these same atmospheric conditions were used to validate theoretical results. however there is an evolution of the cooker temperature is strongly dependent on the solar flux incident. it rises and decreases with the solar flux incident [ , , , , and ]. these discrepancies are due to insufficient thermal sunny exposure at the double glazing; heat losses are significant at the windows. figure . evolution of temperatures (ta, tve, tvi, tac, tp) an function of time during / / . the graphic shows the evolution of the temperature of the absorbing plate, glass (internal and external), air from the cooker and the environment. his study has two stage: a first stage where temperatures grow to reach a peak between h and h when the variation of flux is also rising. the exposure unit is warmed by the absorption of radiation; temperature rises continuously leading the air from the cooker and windows. later than h, there was a decrease, the cooker temperature dropped dramatically at about h when it reached temperatures below °c unlike the theoretical observations. these temperature drops are due firstly to the fact that the solar flux decreases, as well as the energy generating thermal energy. on the other hand the double glazing is not a good thermal warm exposure. apparently it can trap infrared radiation but not the heat energy that is generated. the absorber cools while the temperature of the glass continues to grow. that’s a reversal of the direction of heat exchange at the two windows beyond the solar setting. the cooker gives more heat to the environment than it can receive through the windows and it tends towards a state of thermodynamic equilibrium with it [ ]. figure . influence of the incident flux on the temperature variation during / / . figure . evolution of temperatures (ta, tve, tvi, tac, tp) an function of time during / / . these tests were performed on february , in order to test the performance of the cooker during non-sunny periods. that was a cloudy sky with strong winds. the °c was reached around h unlike the days of strong sunlight. international journal of sustainable and green energy ; ( ): - however the temperature peaked above °c between h and h. this reflects the fact that the conversion of light flow into thermal energy is selective, the live stream is concerned. the default storage is so important because of notorious decreases during cloudy periods. . . tests with load these tests are related to water boil tests and cooking some local dishes. water boiling tests were carried out by measuring the change of the water temperature, the absorber, the air from the cooker and the incident solar flux. figure . water boiling test. this boiling test of a liter of water was performed on feb th , where the ambient temperature varied between ° and °c along the duration of the tests. the maximum flux density incident was w / m² and the average wind speed of . m/s. after hour of pre-heating, the duration of boiling water was h mn and the absorber temperature was °c. a temperature of °c is more than sufficient for all kinds of cooking. since the water does not reach more than °c, a water-based food cooking will not therefore reach a higher temperature than this one. it is found that the water temperature is relatively lower than that of the air from the cooker and absorber. cooking time depends on the dish to be cooked, the amount and intensity of the sun. it varies from to hours. the cooking is not very fast ( to °c are reached), the dishes can, without risk, be left unattesnded. similarly, you can grill walnuts, peanuts or confit fruits, cook eggs (without water), bread, pastries... . conclusion the solar "hot-box" prototype cooker was designed and tested under natural sunlight at the cerer. various tests have shown that the system can reach temperatures sufficient for cooking and pasteurization of water even during periods of low sunlight. the arrangement of the side faces permits to reduce the shadow effects on the absorber, which allows the cooker to heat rapidly enough and at a due time of day. it has an exposure time that is improved enough. the comparative study between theoretical and experimental results that is observed allowed us to move forward on the prospects for improvement of hot-box. the study of the adiabatic transparent materials radiates clearly. the design of thermal storage systems is to improve the daily operating time of the solar cooker. acknowledgements this work was supported by the center of studies and research on renewable energies (cerer) bp. dakar, senegal; nomenclature αab: absorption coefficient of absorber αvin: coefficient of absorption of the glass cp::mass calorific capacity (j.kg - .k - ) ε:emissivity of the material h: convective exchange coefficient (w.m - .k - ) k: thermal conductivity (w.m - .k - ) λ: wave length (m) µ: dynamic viscosity (kg.m - .s - ) mvin:mass of the glass (kg) ρ: density (kg.m - ) σ:stefan-boltzmann constant ( w.m - .k - ) τ: coefficient of transmission of the glass rm: reflection coefficient of mirrors sab: surface of the absorber (m ) svi: surface of the glass (m ) tab: temperature of the absorber (k) tac: room temperature of the cooker (k) tamb: ambient temperature (k) tciel: temperature of the sky (k) tvin: temperature of internal glass (k) tvex: temperature of external glass:(k) Φe: the incoming heat flux (w) Φg: the generated heat flux (w) Φs: outgoing heat flow (w) Φst: stored flow (w) Φth: thermal flux (w) φi: density of incident flux on the surface of the glass (w.m - ) φm: thermal flux density vector (w.m - ) u: enthalpy (j) vv: average wind speed references [ ] flavien tchapga, the opening up of electricity networks in sub-saharan african countries to private capital. organizational choices and institutional constraints '', doctoral thesis, department of economics and management, université paris , june . 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[ ] http://www.boliviainti-sudsoleil.org/ [ ] http://www.feeda.org/ [ ] http://www.techno-science.net/ impacts of deregulation on performance and management of the largest american transportation companies by: timothy w. ruefli date: january abstract: the effects of the past quarter century of deregulation on the transportation industry in the united states are many and varied. impacts have been felt at the level of the industry as a whole, at the level of mode-based industry sub-groups, and at the level of individual firms. analyses and depictions of these impacts have appeared in numerous books and journal articles. in this paper a new, empirically based, methodological approach to industry analysis will be employed to evaluate and illustrate the impacts of deregulation on the relevant levels of this industry in terms of its largest firms. the results of this analysis will be seen to be largely complementary to previous analyses, but will go beyond them in being able to identify in quantitative terms differential impacts of regulatory and other events on individual firms, groups of firms, and the industry from a unified methodological point of view. a later version of this paper appeared in technovation, volume , issues – , october , pages - , doi . / - ( ) -x. keywords: transportation, deregulation ic² institute working paper wp- - - © ic² institute, the university of texas at austin http://ic .utexas.edu impacts of deregulation on performance and management of the largest american transportation companies timothy w. ruefli rex a. and dorothy b. sebastian professor frank c. erwin jr. centennial fellow ic^ institute and graduate school of business the university of texas at austin working paper # - - january ic^ institute, the university of texas, austin, texas please do not quote or cite without permission of author a b s t r a c t t h e e f f e c t s o f t h e p a s t q u a r t e r - c e n t u r y o f d e r e g u l a t i o n o n t h e t r a n s p o r t a t i o n i n d u s t r y i n t h e u n i t e d s t a t e s a r e m a n y a n d v a r i e d . i m p a c t s h a v e b e e n f e l t a t t h e l e v e l o f t h e i n d u s t r y a s a w h o l e , a t t h e l e v e l o f m o d e - b a s e d i n d u s t r y s u b - g r o u p s , a n d a t t h e l e v e l o f i n d i v i d u a l f i r m s . a n a l y s e s a n d d e p i c t i o n s o f t h e s e i m p a c t s h a v e a p p e a r e d i n n u m e r o u s b o o k s a n d j o u r n a l a r t i c l e s . i n t h i s p a p e r a n e w , e m p i r i c a l l y b a s e d , m e t h o d o l o g i c a l a p p r o a c h t o i n d u s t r y a n a l y s i s w i l ! b e e m p l o y e d t o e v a l u a t e a n d i l l u s t r a t e t h e i m p a c t s o f d e r e g u l a t i o n o n t h e r e l e v a n t l e v e l s o f t h i s i n d u s t r y i n t e r m s o f i t s l a r g e s t f i r m s . t h e r e s u l t s o f t h i s a n a l y s i s w i l l b e s e e n t o b e l a r g e l y c o m p l e m e n t a r y t o p r e v i o u s a n a l y s e s , b u t w i l ! g o b e y o n d t h e m i n b e i n g a b l e t o i d e n t i f y i n q u a n t i t a t i v e t e r m s d i f f e r e n t i a l i m p a c t s o f r e g u l a t o r y a n d o t h e r e v e n t s o n i n d i v i d u a l f i r m s , g r o u p s o f f i r m s , a n d t h e i n d u s t r y f r o m a u n i f i e d m e t h o d o l o g i c a l p o i n t o f v i e w . i . i n t r o d u c t i o n t h e t r a n s p o r t a t i o n i n d u s t r y h a s u n d e r g o n e s u b s t a n t i a l c h a n g e s i n t h e l a s t q u a r t e r - c e n t u r y . t h e s e c h a n g e s h a v e b e e n d o c u m e n t e d o n a d a i l y b a s i s i n t h e p r e s s , w e e k l y i n i n d u s t r y a n d n e w s m a g a z i n e s , a n d o v e r l o n g e r p e r i o d s o f t i m e i n s c h o l a r l y b o o k s a n d j o u r n a l a r t i c l e s ( c o w i n g & s t e v e n s o n , l i e b , a l t s h u l e r , s p a d y , t e m p l e , b a r k e r , & s i o a n e , d e p t , o f t r a n s p o r t a t i o n ) . i n t h i s p a p e r we w i l l l o o k a t t h e t h e t r a n s p o r t a t i o n i n d u s t r y f r o m m u l t i p l e p e r s p e c t i v e s i n v o l v i n g t h e t o p o n e h u n d r e d o r s o f i r m s t h a t p a r t i c i p a t e d i n t h a t i n d u s t r y o v e r t h e q u a r t e r c e n t u r y f r o m t o . d e r e g u l a t i o n i m p a c t e d o n d i f f e r e n t s e g m e n t s o f t h e t r a n s p o r t a t i o n i n d u s t r y a t d i f f e r e n t t i m e s a n d i n d i f f e r e n t w a y s . t h e a n a l y s i s p r e s e n t e d h e r e w i l l f o c u s o n t h o s e d i f f e r e n t i a l e f f e c t s a n d e x a m i n e t h e i r i m p l i c a t i o n s f o r m a n a g e m e n t , w i t h s o m e a d d i t i o n a l e m p h a s i s b e i n g p l a c e d o n t h e c a s e o f t h e a i r l i n e s s i n c e t h e i r p e r f o r m a n c e m o r e c l e a r l y r e f l e c t s t h e i s s u e s r a i s e d b y d e r e g u l a t i o n . t h e a n a l y s i s w i l l b e b a s e d o n a n e w m e t h o d o i o g y t h a t c a n e x a m i n e t h e p e r f o r m a n c e o f f i r m s a n d g r o u p s o f f i r m s f r o m t h e p e r s p e c t i v e o f t h e w h o l e i n d u s t r y o r f r o m t h e p e r s p e c t i v e o f s u b g r o u p s w i t h i n t h a t i n d u s t r y . i n p a r t i c u l a r we w i l l c o m p a r e t h e e c o n o m i c p e r f o r m a n c e o f t h e l a r g e s t a i r l i n e , t r u c k i n g a n d r a i l r o a d c o m p a n i e s a s g r o u p s a n d i n t e r m s o f s e l e c t e d i n d i v i d u a l f i r m s , w i t h t h e p e r f o r m a n c e o f t h e l a r g e s t f i r m s i n t h e t r a n s p o r t a t i o n i n d u s t r y a s a w h o l e , a n d w i t h e a c h o t h e r a t t h e i e v e l o f g r o u p s a n d i n d i v i d u a l f i r m s . t h e q u e s t i o n s we w i l l b e c o n c e r n e d w i t h i n c l u d e : h a s d e r e g u l a t i o n g i v e n o n e t r a n s p o r t a t i o n m o d e g r o u p a n a d v a n t a g e o r d i s a d v a n t a g e o v e r o t h e r g r o u p s ? w h a t i n d i v i d u a l f i r m s s t r a t e g i e s h a v e y i e l d e d b e t t e r r e l a t i v e p e r f o r m a n c e i n t h e f a c e o f d e r e g u l a t i o n a n d d o e s t h i s d i f f e r b y m o d e t y p e ? t o s h e d l i g h t o n t h e s e i s s u e s a n e w f o r m o f i n d u s t r y a n a l y s i s w i l l b e e m p i o y e d . w h i l e t h e r e h a v e b e e n n u m e r o u s s t u d i e s o f i n d i v i d u a l t r a n s p o r t a t i o n c o m p a n i e s i n p a r t i c u l a r a n d o f t h e r a i l r o a d , t r u c k i n g , a n d a i r l i n e i n d u s t r i e s i n g e n e r a l , ( f o r t h e l a t t e r , s e e p a r t i c u l a r l y b y r n e s , f r i e d l a n d e r & s p a d y , t a n e j a & , a n d m a n d e i i , f o r t h e m o s t p a r t t h e s e a p p r o a c h e s h a v e r e l i e d o n s t a n d a r d m e t h o d o l o g i e s o f d a t a a n a l y s i s a n d p r e s e n t a t i o n . a l t h o u g h t h e s e s t u d i e s a r e o f t e n d e t a i l e d a n d r e v e a l i n g , t h e y a r e b e s e t w i t h t h e p r o b l e m s o f s c r e e n i n g o u t t h e e f f e c t s o f s h o r t - t e r m b u s i n e s s c y c l e n o i s e , a n d e x t e r n a l e v e n t s , e . g . , t h e e n e r g y c r i s i s , a n d . f o r t h e m o s t p a r t , t h e y e s c h e w c o m p a r i s o n s a c r o s s d i f f e r e n t s e g m e n t s o f t h e t r a n s p o r t a t i o n i n d u s t r y . i n t h i s c h a p t e r we w i l l u s e a n e w m e t h o d o l o g y b a s e d o n t h e a n a l y s i s o f o r d i n a l t i m e s e r i e s , i . e . , r a n k i n g s o f f i r m s o v e r t i m e , t o s c r e e n o u t t h e b a c k g r o u n d n o i s e o f s h o r t - t e r m b u s i n e s s c y c l e s a n d t h o s e e x t e r n a l e v e n t s t h a t h a d no d i f f e r e n t i a l e f f e c t o n t h e i n d u s t r y i n q u e s t i o n a n d t o p e r m i t i mme d i a t e a n d m e a n i n g f u l c r o s s - s e g m e n t c o m p a r i s o n s . w h i l e t h e d e t a i l s o f t h i s m e t h o d o l o g y a r e r e a d i l y a c c e s s i b l e t o m o s t m a n a g e r s , , t h e e m p h a s i s h e r e w i l l n o t b e o n t h e d e t a i l s o r m e c h a n i c s o f t h e m e t h o d o l o g y , r a t h e r we w i l l b e c o n c e r n e d w i t h w h a t n e w l i g h t a n e w m e t h o d o l o g y c a n s h e d o n t h e i m p o r t a n t p r o b l e m o f t h e m a n a g i n g t h e i m p a c t s o f d e r e g u l a t i o n o n i n d i v i d u a l f i r m s a n d g r o u p s o f f i r m s . i . m e t h o d o l o g y i n a n a l y z i n g a s y s t e m a s c o m p l e x a s t h a t r e p r e s e n t e d b y t h e l a r g e s t t r a n s p o r t a t i o n c o m p a n i e s , s e v e r a l p r o b l e m s m u s t b e f a c e d . t h e p r o b l e m s i n v o l v e m a k i n g c o m p a r i s o n s a c r o s s m u l t i p l e d i m e n s i o n s , m u l t i p l e t i m e p e r i o d s , m u l t i p l e f i r m s , m u l t i p l e l e v e l s , a l l i n a h i e r a r c h y o f c o n t e x t s , a n d t h e p r o b l e m o f s c r e e n i n g o u t n o i s e i n t h e d a t a ( s e e m i l l e r & f r i e s e n ( ) ) . t o m a n a g e t h e s e p r o b l e m s we w i l l u s e a t e c h n i q u e t h a t i s b a s e d ' o n t h e a n a l y s i s o f t h e r a n k i n g s o f f i r m s a n d g r o u p s o f f i r m s o v e r t i m e . t h a t i s , we w i l l t a k e t h e p e r f o r m a n c e d a t a f o r e a c h f i r m i n e a c h y e a r a l o n g e a c h d i m e n s i o n a n d r a n k t h a t f i r m a g a i n s t a i l o t h e r f i r m s . t h e s e s e t s o f r a n k s a r e w h a t we s h a l l u s e i n o u r a n a l y s i s . t h i s w i l l p e r m i t u s t o c o m p a r e t h e r a n k i n g o f a f i r m b a s e d o n r e v e n u e d i r e c t l y w i t h i t s r a n k b a s e d o n n e t i n c o m e . we c a n a l s o c o m p a r e t h e r a n k s o f t wo d i f f e r e n t f i r m s b a s e d o n t h e i r r e v e n u e a n d we c a n c o m p a r e t h e a s s e t r a n k o f a f i r m i n o n e y e a r w i t h i t s a s s e t r a n k i n a n y o t h e r y e a r w i t h o u t h a v i n g t o w o r r y a b o u t w h a t w a s t h e r a t e o f i n f l a t i o n , e t c . t h e c o m p a r i s o n s w i l l t h u s a l l b e r e l a t i v e t o t h e b e h a v i o r s o f t h e r e s t o f t h e f i r m s i n t h e s e t b e i n g e x a m i n e d . we c a n a l s o c o m p a r e t h e r a n k i n g s o f a f i r m w i t h r a n k i n g s o f o t h e r f i r m s i n i t s i n d u s t r y , o r w i t h o n l y t h o s e f i r m s i n s o m e s u b g r o u p . f r o m t h e r a n k s o f i n d i v i d u a l f i r m s we c a n g e n e r a t e a g g r e g a t e r a n k s t a t i s t i c s a t t h e l e v e l o f t h e i n d u s t r y a s a w h o l e a n d a l s o f o r a n y s u b g r o u p i n t h e i n d u s t r y . a t a n y l e v e l , u s e o f r a n k s g i v e s u s a d i r e c t b e n c h m a r k a g a i n s t w h i c h t o e v a l u a t e t h e p e r f o r m a n c e o f a f i r m o r g r o u p o f f i r m s . a n y c h a n g e s t h a t a f f e c t a l l f i r m s i n t h e s a m e f a s h i o n , s a y , i n f l a t i o n , w i l l n o t s h o w up i n t h e a n a l y s i s o f t h e r a n k i n g s , b u t a n y f a c t o r s t h a t a f f e c t f i r m s d i f f e r e n t l y , s a y , t h e r e d u c t i o n o f r e g u l a t i o n s a f f e c t i n g o n l y a i r l i n e s , w i l l , i f e f f e c t i v e a n d i f n o t o f f s e t b y o t h e r f a c t o r s , s h o w u p i n t h e c h a n g e o f r a n k i n g s o f a i r l i n e s r e l a t i v e t o n o n - a i r l i n e s . g i v e n t h e r a n k i n g s o f t h e i n d i v i d u a l f i r m s i n a n i n d u s t r y , t h e r a n k i n g s a l o n g a p a r t i c u l a r d i m e n s i o n f o r a g r o u p o f f i r m s c a n b e c o m p u t e d s i m p l y b y t a k i n g t h e a v e r a g e r a n k i n g o f a l l t h e f i r m s i n t h e g r o u p a l o n g t h a t d i m e n s i o n f o r a g i v e n y e a r . t h i s i s a c c o m p l i s h e d b y s u m m i n g up t h e r a n k i n g s f o r t h e i n d i v i d u a l f i r m s i n t h e g r o u p f o r e a c h y e a r a n d d i v i d i n g b y t h e n u m b e r o f f i r m s . t h u s we c a n c o m p u t e t h e a v e r a g e r a n k p o s i t i o n o f t h e a i r l i n e s v e r s u s t h e r a i l r o a d s v e r s u s t r u c k i n g f i r m s , e t c . i n a d d i t i o n t o g e n e r a t i n g a m e a s u r e o f t h e r a n k p o s i t i o n o f a g r o u p o f f i r m s , we c a n a l s o e a s i l y c o m p u t e a m e a s u r e o f t h e v o l a t i l i t y o f r a n k s h i f t a c t i v i t y f o r a n i n d u s t r y o r f o r a n y g r o u p o f f i r m s w i t h i n t h e i n d u s t r y . t h i s i s d o n e f o r e a c h p e r f o r m a n c e d i m e n s i o n , f o r e a c h y e a r b y s u b t r a c t i n g t h e r a n k i n t h e p r e v i o u s y e a r f r o m t h e r a n k i n t h e t a r g e t y e a r f o r e a c h f i r m i n t h e g r o u p , a d d i n g up t h o s e r a n k s h i f t s w i t h o u t r e g a r d t o w h e t h e r t h e y a r e n e g a t i v e o r p o s i t i v e s h i f t s , a n d t h e n d i v i d i n g t h e t o t a l b y t h e n u m b e r o f f i r m s i n t h e g r o u p . a t h i r d u s e f u l m e a s u r e i n a n a l y z i n g t h e b e h a v i o r o f a g r o u p o f f i r m s i s t o m e a s u r e t h e u n c e r t a i n t y a s s o c i a t e d w i t h t h e c h a n g e o f r a n k p o s i t i o n s . t h i s c a n b e a c c o m p l i s h e d b y c o m p u t i n g t h e r e l a t i v e p r o b a b i l i t y o f a f i r m s t a y i n g i n i t s p r e s e n t r a n k i n t h e n e x t y e a r , s h i f t i n g t o a h i g h e r r a n k , o r s h i f t i n g t o a l o w e r r a n k . t h e d e t a i l s o f t h i s c o m p u t a t i o n a r e p r e s e n t e d i n r u e f l i , s a l a z a r , a n d w i l s o n ( } a n d w i l l n o t b e r e p e a t e d h e r e . i i i . d a t a t h e u s u a l a p p r o a c h t o i n d u s t r y a n a l y s i s i s t o u s e a b s o l u t e l e v e l s o f p e r f o r m a n c e o r r a t i o s o f t h o s e a b s o l u t e l e v e l s . t h e a p p r o a c h h e r e u t i l i z e s i n p u t d a t a i n t h e f o r m o f r a n k i n g s o f f i r m p e r f o r m a n c e o v e r t i m e f o r e a c h o f t h e s e l e c t e d p e r f o r m a n c e d i m e n s i o n s . i f t h e d a t a o n f i r m p e r f o r m a n c e a r e i n c a r d i n a l f o r m ( i . e . , a b s o l u t e n u m e r i c a l l e v e l s o f p e r f o r m a n c e o r t h e i r r a t i o s ) t h e y m u s t b e t r a n s f o r m e d t o y i e l d o r d i n a l r a n k i n g s , t h a t i s , t h e f i r m s m u s t b e o r d e r e d ( e . g . , s o r t e d o r i n d e x e d ) e a c h y e a r a i o n g e a c h d i m e n s i o n , a n d a s s i g n e d r a n k s b a s e d o n t h e i r p e r f o r m a n c e . t h e d a t a we w i l l u s e h e r e a r e t h e r a n k i n g s d e v e l o p e d b y f o r t u n e m a g a z i n e f o r t h e t r a n s p o r t a t i o n i n d u s t r y f o r t h e p e r i o d t o , t h e p a r t i c u l a r d i m e n s i o n s o f r a n k i n g s e x a m i n e d h e r e i n c l u d e o p e r a t i n g r e v e n u e , n e t i n c o m e , r e t u r n o n e q u i t y , a s s e t s , a n d n u m b e r o f e m p l o y e e s . t h e l a t t e r r a n k i n g s a r e a v a i l a b l e o n l y f r o m t o . a s w i t h a n y d a t a , t h e f o r t u n e r a n k i n g s h a v e s o m e l i m i t a t i o n s t h a t s h o u l d b e n o t e d . f i r m s a r e i n c l u d e d i n t h e f o r t u n e t r a n s p o r t a t i o n f i l e i f t h e y a r e p u b l i c l y l i s t e d u . s . f i r m s a n d i f m o r e t h a n % o f t h e i r o p e r a t i n g r e v e n u e s c o me f r o m t r a n s p o r t a t i o n - r e i a t e d a c t i v i t i e s . r a n k i n g s a l o n g t h e o t h e r d i m e n s i o n s s e l e c t e d f o r a n a l y s i s : n e t i n c o m e , a s s e t s , a n d r e t u r n o n e q u i t y a r e c o n t i n g e n t o n t h e f i r m b e i n g i n t h e t o p a l o n g t h e d i m e n s i o n o f r e v e n u e . t h u s t h e r e m a y b e f i r m s t h a t h a v e n e t i n c o m e o r o t h e r p e r f o r m a n c e f i g u r e s t h a t w o u l d p l a c e t h e m i n t h e t o p f i f t y b y t h a t m e a s u r e , b u t b e c a u s e t h e i r r e v e n u e f i g u r e s a r e n o t h i g h e n o u g h , t h e y a r e n o t l i s t e d . s i n c e f i r m s a r e c l a s s i f i e d a s b e i n g i n a n i n d u s t r y o n t h e b a s i s o f t h e i r r e v e n u e s , s i n g l e p r o d u c t o r s e r v i c e f i r m s a r e l u m p e d t o g e t h e r w i t h n e a r ­ c o n g l o m e r a t e s . a l s o , s i n c e o n l y t h e l a r g e s t f i r m s i n t h e i n d u s t r y a r e r a n k e d b y f o r t u n e , t h a t p o r t i o n o f i n d u s t r y a c t i v i t y a t t r i b u t a b l e t o t h e n u m b e r o f s m a l l , g r o w i n g , a n d p o t e n t i a l l y i m p o r t a n t f i r m s w i l l n o t b e i n c o r p o r a t e d d i r e c t l y i n t o t h e a n a l y s i s u n t i l t h o s e f i r m s a r e i n t h e t o p f i f t y f i r m s . t h u s t h i s a n a l y s i s i s f r o m t h e p o i n t o f v i e w o f t h e i n c u m b e n t s i n t h e i n d u s t r y a n d s h o u l d b e i n t e r p r e t e d f r o m t h a t p e r s p e c t i v e . t wo c o n v e n t i o n s s h o u l d b e n o t e d a t t h e o u t s e t . b y c o n v e n t i o n m e r g e r s o f r a n k e d t r a n s p o r t a t i o n f i r m s w i t h f i r m s o u t s i d e t h e t o p f i f t y d i d n o t r e s u l t i n a n e w e n t i t y a n d w e r e t r e a t e d a s a c o n t i n u a t i o n o f t h e p r e v i o u s i y - r a n k e d f i r m f o r t h e p u r p o s e s o f t h e a n a l y s i s . i n t h e e v e n t o f a m e r g e r b e t w e e n t w o p r e v i o u s l y r a n k e d f i r m s , t h e e n t i t i e s p r i o r t o t h e m e r g e r w e r e c o n s i d e r e d t o h a v e b e e n d r o p p e d f r o m t h e r a n k i n g s f o l l o w i n g t h e m e r g e r a n d t h e r e s u l t i n g e n t i t y w a s t r e a t e d a s a n e w l y - r a n k e d f i r m . b e c a u s e f i r m s l e a v e a n d e n t e r t h e t o p f i f t y f r o m y e a r t o y e a r a n d a r e n o t r a n k e d w h e n t h e y a r e n o t i n t h e t o p f i f t y a c o n v e n t i o n o f a s s i g n i n g a r a n k o f " s i " t o u n r a n k e d f i r m s w a s a d o p t e d . t h i s w a s f e l t t o be c o n s e r v a t i v e w i t h r e s p e c t t o t h e a n a l y s i s i n s o f a r a s t h e a c t u a l r a n k o f f i r m s o u t s i d e t h e t o p f i f t y i s , i n a l l b u t a t m o s t o n e c a s e , g r e a t e r t h a n . i v . i n d u s t r y r e s u l t s i n o r d e r t o p l a c e t h e e v a l u a t i o n o f t h e i m p a c t s o f d e r e g u l a t i o n o n t h e p e r f o r m a n c e o f t h e l a r g e s t t r a n s p o r t a t i o n c o m p a n i e s i n p e r s p e c t i v e , we w i l l f i r s t a n a l y z e t h e r a n k s h i f t b e h a v i o r o f t h e t o p f i f t y t r a n s p o r t a t i o n f i r m s a s a g r o u p . we w i l l t h e n d e c o m p o s e t h i s g r o u p i n t o s u b g r o u p s b a s e d o n t r a n s p o r t a t i o n m o d e s a n d a n a l y z e t h e p e r f o r m a n c e o f s e l e c t e d w h o l e s u b g r o u p s . f o l l o w i n g t h a t we w i l l f o c u s o n r e p r e s e n t a t i v e i n d i v i d u a l f i r m s i n t h e r a i l r o a d a n d t r u c k i n g s u b g r o u p s a n d e v a l u a t e t h e i r p e r f o r m a n c e i n r e l a t i o n t o t h e t o p f i f t y t r a n s p o r t a t i o n f i r m s . t h e a n a l y s i s w i l l c o n c l u d e w i t h a n e x a m i n a t i o n o f s e l e c t e d a i r l i n e c o m p a n i e s r e l a t i v e t o a l l t o p t r a n s p o r t a t i o n f i r m s . a . t r a n s p o r t a t i o n f i r m s a v e r a g e r a n k p o s i t i o n i s a m e a n i n g l e s s m e a s u r e f o r t h e i n d u s t r y a s a w h o l e , s i n c e i t i s a c o n s t a n t f o r e a c h y e a r ? r a n k s h i f t v o l a t i l i t y i s , h o w e v e r a u s e f u l m e a s u r e a t t h i s l e v e l . t h e i n c r e a s i n g t u r b u l e n c e i n t h e t r a n s p o r t a t i o n i n d u s t r y i n t h e p a s t t wo a n d o n e - h a l f d e c a d e s c a n b e c l e a r l y s e e n i n f i g u r e , w h e r e t h e v o l a t i l i t y ( m e a s u r e d b y t h e a v e r a g e a b s o l u t e l e v e l o f r a n k s h i f t s f r o m o n e y e a r t o t h e n e x t ) i s g r a p h e d . f r o m i n s e r t f i g u r e h e r e x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x t h r o u g h t h e m i d d l e ' s v o l a t i l i t y l e v e l s w e r e s t a b l e a c r o s s a l l d i m e n s i o n s , w i t h t h e a v e r a g e f i r m s h i f t i n g o n e p o s i t i o n o r l e s s o n o p e r a t i n g r e v e n u e a n d a s s e t r a n k i n g s , t w o p o s i t i o n s o n n e t i n c o m e r a n k i n g s , a n d f o u r p o s i t i o n s o r l e s s o n r e t u r n o n e q u i t y r a n k i n g s . i n t h e l a t e r s i x t i e s , a s t h e f i g u r e s h o w s , v o l a t i l i t y r o s e o n a l l d i m e n s i o n s , p e a k i n g i n w i t h t h e e c o n o m y - w i d e m e r g e r a n d a c q u i s i t i o n w a v e a n d t h e r e o r g a n i z a t i o n o f t h e e a s t e r n r a i l r o a d s . a f t e r a s e t t l i n g d o w n p e r i o d i n t h e e a r l y ' s , v o l a t i l i t y l e v e l s b e g a n a g e n e r a l l o n g - t e r m i n c r e a s e t h a t c o n t i n u e s t o t h e p r e s e n t . r e c e n t v o l a t i l i t y l e v e l s a r e d o u b l e t h o s e o f a q u a r t e r - c e n t u r y a g o , w i t h v o l a t i l i t y i n r e t u r n o n e q u i t y s p i k i n g t o v e r y h i g h l e v e l s i n a n d . t h i s i s a g r a p h i c d e p i c t i o n o f t h e i m p a c t s o f d e r e g u l a t i o n a n d i n c r e a s e d e c o n o m i c u n c e r t a i n t y o n t h e i n d u s t r y , a n d s u g g e s t s t h a t t h e m a n a g e m e n t e n v i r o n m e n t o f t h e f i r m s i n t h e i n d u s t r y i s l i k e l y t o b e s i g n i f i c a n t l y d i f f e r e n t t h a n i t w a s j u s t a d e c a d e a g o . t h e t o p s e c t i o n o f t a b l e s h o w s t h e u n c e r t a i n t y a s s o c i a t e d w i t h t h e r a n k s h i f t s a l o n g t h e v a r i o u s d i m e n s i o n s o f p e r f o r m a n c e f o r t h e t r a n s p o r t a t i o n i n d u s t r y . t h e l e v e l s r e p o r t e d a r e p e r c e n t a g e s o f t h e l e v e l o f u n c e r t a i n t y t h a t w o u l d e x i s t i f r a n k c h a n g e s w e r e a t o t a l l y r a n d o m p r o c e s s . t h e r e s u l t s a r e n o t a l l a s m i g h t b e e x p e c t e d . r e t u r n o n e q u i t y s h i f t s a r e m o s t u n c e r t a i n , f o l l o w e d b y n e t i n c o m e s h i f t s , o p e r a t i n g r e v e n u e , a n d a s s e t s , i n s e r t t a b l e h e r e w i t h s h i f t s b a s e d o n t h e n u m b e r o f e m p i o y e e s , s o m e w h a t s u r p r i s i n g l y , b e i n g t h e m o s t c e r t a i n ( i . e . , l e a s t l i k e l y t o o c c u r ) . t h e i m p l i c a t i o n h e r e i s t h a t t h e f i r m s i n t h e t r a n s p o r t a t i o n i n d u s t r y t e n d t o a d j u s t t h e i r w o r k - f o r c e s i n a mo r e c o n s i s t e n t w a y t h a n t h e y a d j u s t a s s e t l e v e l s o r m a r k e t s h a r e . we w i l l n o w e x a m i n e a n d c o n t r a s t t h e b e h a v i o r o f f o u r t r a n s p o r t a t i o n i n d u s t r y s u b g r o u p s , r a i l r o a d s , a i r l i n e s , t r u c k i n g , a n d p i p e l i n e s i n t h e c o n t e x t o f t h e g e n e r a l i n c r e a s i n g i n s t a b i l i t y o f t h e t o p t r a n s p o r t a t i o n f i r m s . b . r a i l r o a d s t h e c o n t r i b u t i o n o f t h e t o p r a i l r o a d f i r m s t o t h e v o l a t i l i t y o f t h e t o p t r a n s p o r t a t i o n f i r m s c a n b e a s s e s s e d f r o m f i g u r e . h e r e i n i t c a n b e s e e n t h a t t h e r a i l r o a d s w e r e m a j o r c o n t r i b u t o r s i n s e r t f i g u r e h e r e t o t h e s p i k e i n r a n k s h i f t a c t i v i t y i n a n d t o r e t u r n o n e q u i t y a c t i v i t y i n a n d , b u t , o t h e r t h a n t h a t , w e r e n o t a s v o l a t i l e i n t h e i r a c t i v i t y a s w a s t h e a v e r a g e t r a n s p o r t a t i o n f i r m . i n t h e p o s t - p e r i o d t h e a c t i v i t y l e v e l s o f t h e v a r i o u s d i m e n s i o n s m o v e mo r e i n c o n c e r t w i t h e a c h o t h e r , w i t h a r i s i n g t r e n d i n t h e l a s t d e c a d e . b e f o r e e x a m i n i n g t h e a v e r a g e r a n k p o s i t i o n o f t h e r a i l r o a d s , a w o r d a b o u t i n t e r p r e t i n g t h e p o s i t i o n g r a p h s i s i n o r d e r . t h e f i r m w i t h t h e l a r g e s t a c t u a l p e r f o r m a n c e m e a s u r e i s g i v e n t h e r a n k o f o n e , t h e h i g h e s t r a n k ? t h e f i r m w i t h t h e n e x t l a r g e s t v a l u e o f t h e a c t u a l p e r f o r m a n c e m e a s u r e i s g i v e n t h e r a n k o f t w o , e t c . t h e h i g h e s t r a n k s a p p e a r a t t h e b o t t o m o f t h e p o s i t i o n g r a p h s - a c o n v e n t i o n e n f o r c e d b y t h e g r a p h i c s p a c k a g e u s e d . s o t h e l o w e r t h e p h y s i c a l p o s i t i o n o n t h e g r a p h , t h e h i g h e r t h e r a n k i n g . a s f i g u r e s h o w s , t h e p e r f o r m a n c e o f t h e l a r g e s t r a i l r o a d s , r e l a t i v e t o o t h e r l a r g e t r a n s p o r t a t i o n f i r m s , h a s w o r s e n e d o v e r t h e p e r i o d o f t h e s t u d y . t h e w o r s e n i n g h a s o c c u r r e d o n a l l d i m e n s i o n s , a l t h o u g h n o t u n i f o r m l y . a s s e t , e m p l o y e e , a n d o p e r a t i n g r e v e n u e p o s i t i o n h a v e w o r s e n e d i n a l m o s t e v e r y y e a r . n e t i n c o m e a n d r e t u r n o n e q u i t y p o s i t i o n s i m p r o v e d i n t h e r e o r g a n i z a t i o n p e r i o d j u s t b e f o r e , a n d b o t h h e l d s t e a d y o r i m p r o v e d s l i g h t l y d u r i n g t h e e n e r g y c r i s i s . r e t u r n o n e q u i t y h a s i n s e r t f i g u r e h e r e h a d t h e w o r s t p o s i t i o n i n a l l b u t t wo y e a r s a n d e x h i b i t s a m u c h m o r e p r o n o u n c e c y c l i c p a t t e r n t h a n d o t h e o t h e r d i m e n s i o n s . t h e o t h e r t wo i m p r o v e m e n t p e r i o d s i n r e t u r n o n e q u i t y p o s i t i o n i n - a n d - f o l l o w e d l e g i s l a t i o n a i m e d a t h e l p i n g t h e r a i i r o a d s . m e a s u r e m e n t o f p r o d u c t i v i t y o f l a b o r i n t h e t r a n s p o r t a t i o n h a s b e e n a m a j o r m e t h o d o l o g i c a l p r o b l e m c l i e b c ) , p . . t h e m e t h o d o l o g y u s e d h e r e p r o v i d e s a r e a d y i n d i c a t i o n o f r e l a t i v e p r o d u c t i v i t y . t h e r e l a t i o n o f r a n k b y n u m b e r o f e m p l o y e e s r e l a t i v e t o t h e r a n k i n g s o n o t h e r d i m e n s i o n s g i v e s a n i n d i c a t i o n o f t h e r e l a t i v e p r o d u c t i v i t y o f l a b o r . f o r e x a m p l e , r a n k i n g b y n u m b e r o f e m p l o y e e s t h a t i s h i g h e r i n r a n k t h a n t h a t o f o p e r a t i n g r e v e n u e , a s i s t h e c a s e f o r r a i l r o a d s , i n d i c a t e s a r e l a t i v e l y p o o r a v e r a g e s a l e s p e r e m p l o y e e i n c o m p a r i s o n t o o t h e r f i r m s i n t h e r a n k i n g s . t h e h i g h e r a v e r a g e r a n k p o s i t i o n o f n u m b e r o f e m p l o y e e s w h e n c o m p a r e d t o n e t i n c o me a l s o i n d i c a t e s a r e l a t i v e l y a d v e r s e p r o f i t p e r e m p l o y e e . t h e r a n k d a t a a l s o s h o w t h a t t h e e n e r g y c r i s i s i n t h e e a r l y ' s h a d l i t t l e i m p a c t o n t h e r a i l r o a d s r e l a t i v e t o o t h e r t r a n s p o r t a t i o n f i r m s . a s f i g u r e s h o w s , t h e r e i s n o s i g n i f i c a n t s h i f t i n a v e r a g e r a n k p o s i t i o n i n t h e p e r i o d o f t h e s h a r p i n c r e a s e s i n t h e p r i c e o f o i l . t h i s m e a n s t h a t r a i l r o a d s w e r e n o m o r e o r l e s s s e n s i t i v e t o p r i c e i n c r e a s e s o r s h o r t a g e s o f f u e l s u p p l y t h a n o t h e r t r a n s p o r t a t i o n m o d e s - g i v e n t h e g o v e r n m e n t a l l o c a t i o n p r o g r a m s i n p l a c e a t t h e t i m e . r e t u r n i n g t o t a b l e we c a n n o t e t h a t t h e r a i l r o a d s f o l l o w e d t h e p a t t e r n o f t h e t r a n s p o r t a t i o n i n d u s t r y a s a w h o l e i n t e r m s o f t h e u n c e r t a i n t y o f t h e r a n k s h i f t s i n t h e p e r i o d t o . c . a i r l i n e s t h e t o p a i r l i n e f i r m s s h o w a s u b s t a n t i a l l y d i f f e r e n t p a t t e r n o f r a n k s h i f t a c t i v i t y t h a n d i d t h e r a i l r o a d s o r t h e t h e t o p t r a n s p o r t a t i o n f i r m s a s a w h o l e . a i r l i n e s m a k e o n l y a m o d e s t c o n t r i b u t i o n t o t h e s p i k e i n r a n k s h i f t a c t i v i t y i n a l l t r a n s p o r t a t i o n s i n ( s e e f i g u r e ) , b u t d o h a v e a s i z a b l e s p i k e o f t h e i r o wn o n t h e d i m e n s i o n s o f n e t i n c o m e a n d r e t u r n o n e q u i t y i n ( f i g u r e ) . t h i s w a s a r e s u l t o f a d v e r s e a i r l i n e i n d u s t r y c o n d i t i o n s i n t h a t p e r i o d ( a s i n d i c a t e d b y t h e o n l y x x * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * i n s e r t f i g u r e h e r e x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x n o m i n a l i n c r e a s e i n o p e r a t i n g r e v e n u e a n d a s s e t r a n k s h i f t a c t i v i t y ) r a t h e r t h a n a r e s u l t o f m e r g e r a n d a c q u i s i t i o n o r r e o r g a n i z a t i o n ( w h i c h w o u l d h a v e g e n e r a t e d s h i f t s i n a l l d i m e n s i o n s ) . n o t i c e t h a t o p e r a t i n g r e v e n u e a n d a s s e t r a n k s h i f t s r e m a i n a t a c o n s i s t e n t l y l o w l e v e l u n t i l . a s d e r e g u l a t i o n o c c u r s , r a n k s h i f t s o n t h e s e t wo d i m e n s i o n s b e g i n t o i n c r e a s e s h a r p l y , q u a d r u p l i n g b y a n d i m p r o v i n g s o m e w h a t i n t h e l a s t t wo p e r i o d s . a t t h e s a me t i me n e t i n c o me a n d r e t u r n o n e q u i t y a c t i v i t y c o n t i n u e t h e i r c y c l i c p a t t e r n a r o u n d a n i n c r e a s i n g t r e n d l i n e o r i g i n a t i n g i n . t h e a v e r a g e r a n k p o s i t i o n o f t h e a i r l i n e c o m p a n i e s h a s s t e a d i l y i m p r o v e d i n t h e p e r i o d t o , a s f i g u r e s h o w s . i m p r o v e m e n t h a s b e e n r e l a t i v e l y u n i f o r m o n o p e r a t i n g r e v e n u e i n s e r t f i g u r e h e r e a n d a s s e t d i m e n s i o n s , w i t h n e t i n c o m e a n d r e t u r n o n e q u i t y f o l l o w i n g t h e c y c l i c p a t t e r n i n t h e p o s t - p e r i o d a s n o t e d a b o v e . t h e e f f e c t s o f t h e r a t e f r e e z e f r o m t o c a n b e s e e n c l e a r l y i n t h e o r d i n a l d a t a . f o r t h e f i r s t f o u r y e a r s o f t h e f r e e z e , t h e a v e r a g e r e t u r n o n e q u i t y d r a m a t i c a l l y i m p r o v e s p o s i t i o n a n d t h e n w o r s e n s s o m e w h a t i n t h e i a s t t h r e e y e a r s o f t h e p e r i o d . n e t i n c o me p o s i t i o n , o n t h e o t h e r h a n d , i mp r o v e s i n p o s i t i o n i n a l i b u t t h e l a s t y e a r o f t h e f r e e z e . t h e n e t e f f e c t o f t h e f r e e z e w a s t o l e a v e t h e a i r l i n e s i n a r e l a t i v e l y b e t t e r p o s i t i o n t h a n b e f o r e . w i t h t h e r a t e s u n f r o z e n i n t h e a i r l i n e r e t u r n o n e q u i t y a n d n e t i n c o m e p o s i t i o n s r e t u r n e d t o t h e i r i m p r o v i n g t r e n d u n t i l . t h e l a s t c y c l e o n t h e s e t wo d i m e n s i o n s p e a k e d i n , f o l l o w e d b y t wo y e a r s o f r e l a t i v e i mp r o v e m e n t , i n c o n t r a s t t o t h e r a i l r o a d s , t h e l e v e l s o f u n c e r t a i n t y a s s o c i a t e d w i t h r a n k s h i f t s o n t h e v a r i o u s p e r f o r m a n c e d i m e n s i o n s ( t a b l e ) d o n o t f o l l o w t h e i n d u s t r y p a t t e r n . r e t u r n o n e q u i t y a n d n e t i n c o m e a r e t h e t wo m o s t u n c e r t a i n m e a s u r e s , b o t h a t l e v e l s we i i a b o v e t h e i n d u s t r y a v e r a g e . h o w e v e r a s s e t s h i f t s a r e n e x t i n u n c e r t a i n t y , f o i l o w e d b y e m p l o y e e r a n k s h i f t s . f o r t h e a i r l i n e s , r a n k s h i f t s o n o p e r a t i n g r e v e n u e p e r f o r m a n c e a r e t h e m o s t c e r t a i n , i n d i c a t i n g t h a t a i r l i n e s a r e r e i a t i v e i y s t a b l e w i t h r e s p e c t t o m a r k e t s h a r e . t h i s i m p l i e s t h a t a i r l i n e s h a v e m o r e o f a m a r k e t s h a r e s t r a t e g y e m p h a s i s i n t h e i r c o r p o r a t e d e c i s i o n ­ m a k i n g t h a n d o t h e o t h e r t r a n s p o r t a t i o n m o d e s . a c c o r d i n g t o t h e d a t a p r e s e n t e d h e r e , a i r l i n e m a n a g e r s , i n c o m p a r i s o n w i t h m a n a g e r s o f o t h e r t r a n s p o r t a t i o n f i r m s h a v e a c c e p t e d w i d e r s w i n g s i n r e l a t i v e l e v e l s o f n e t i n c o m e , r e t u r n o n e q u i t y , a s s e t s , a n d e v e n l e v e l s o f t h e i r w o r k - f o r c e s i n o r d e r t o s t a b i l i z e m a r k e t s h a r e . r e c e n t h i g h e r l e v e l s o f m a r k e t s h a r e s t a b i l i t y i n d i c a t e t h a t t h e f o c u s o n t h i s s t r a t e g i c d i m e n s i o n h a s i n c r e a s e d a s d e r e g u l a t i o n h a s t a k e n e f f e c t . i n a s m a l l d i v e r g e n c e f r o m t h e s i t u a t i o n w i t h t h e r a i l r o a d s , t h e a i r l i n e s a s a g r o u p s h o w s o m e e f f e c t s o f t h e e n e r g y c r i s i s r e l a t i v e t o o t h e r t r a n s p o r t a t i o n f i r m s . f i g u r e s h o w s a r e i a t i v e i y s m o o t h t r a n s i t i o n i n r a n k p o s i t i o n t h r o u g h t h e p e r i o d o f o i l p r i c e i n c r e a s e s f o r o p e r a t i n g r e v e n u e a n d a s s e t s , b u t t h e w o r s e n i n g o f t h e n e t i n c o m e a n d r e t u r n o n e q u i t y p o s i t i o n s f r o m t o c a n , i n p a r t , b e a t t r i b u t e d t o r i s i n g f u e l p r i c e s . t h i s i n d i c a t e s t h a t a i r l i n e s w e r e r e l a t i v e l y m o r e s e n s i t i v e t o f u e l p r i c e s t h a n w e r e t h e r a i l r o a d s . t h i s i s n o t u n e x p e c t e d s i n c e a i r l i n e s h a v e l o w f u e l e f f i c i e n c i e s w h e n c o m p a r e d t o o t h e r t r a n s p o r t a t i o n m o d e s c l i e b c } , p . ] . i t i s a l s o i n t e r e s t i n g t o c o m p a r e t h e r e l a t i v e p o s i t i o n o f a v e r a g e r a n k b y n u m b e r o f e m p l o y e e s f o r t h e a i r l i n e s a n d r a i l r o a d s . n o t e t h a t i n f i g u r e , w i t h t h e e x c e p t i o n o f t h e l a s t y e a r , a v e r a g e e m p l o y e e r a n k f o r t h e a i r l i n e s i s w o r s e t h a n a v e r a g e r e v e n u e r a n k . t h e i n t e r p r e t a t i o n o f t h i s i s t h a t a i r l i n e s h a v e h a d f a v o r a b l e emp i o y e e p r o d u c t i v i t y i n t e r m s o f r e v e n u e g e n e r a t e w h e n c o m p a r e d t o o t h e r t r a n s p o r t a t i o n f i r m s . t h e d a t a i n d i c a t e t h a t t h i s a d v a n t a g e h a s m o v e d t o a p a r i t y p o s i t i o n i n ( w h e n a v e r a g e r e v e n u e r a n k e q u a l e d a v e r a g e e m p l o y e e r a n k ) a n d w a s r e v e r s e d i n . d. t r u c k i n g t h e p a t t e r n o f v o l a t i l i t y o f r a n k s h i f t s i n t h e t r u c k i n g s u b g r o u p i s h o w n i n f i g u r e . i n t h e f i r s t d e c a d e s t u d i e d i n s e r t f i g u r e h e r e o p e r a t i n g r e v e n u e , a s s e t , a n d n e t i n c o m e s h i f t s a r e l o w a n d c o m p a r a b l e , o n l y r e t u r n o n e q u i t y s h o w s m o d e r a t e l e v e l s o f v o l a t i l i t y . t h i s w a s , o f c o u r s e , a p e r i o d o f s u b s t a n t i a l r e g u l a t i o n i n t h e t r u c k i n g i n d u s t r y . b e g i n n i n g i n v o l a t i l i t y o n a l l d i m e n s i o n s i n c r e a s e s w i t h r e t u r n o n e q u i t y a n d n e t i n c o m e v o l a t i l i t y d o i n g s o s h a r p l y . t h i s i n c r e a s e p e a k s i n a n d i s a m a j o r c o n t r i b u t o r t o t h e p e a k i n t r a n s p o r t a t i o n v o l a t i l i t y i n t h a t p e r i o d . a f t e r a b r i e f l u l l i n t h e a g g r e g a t e r a n k s h i f t a c t i v i t y o n a l l d i m e n s i o n s r e s u m e s i t s u p w a r d t r e n d . n o t i c e t h a t r e t u r n o n e q u i t y a n d n e t i n c o m e v o l a t i l i t i e s m o v e t o g e t h e r a n d , t o a n e v e n g r e a t e r d e g r e e , s o d o o p e r a t i n g r e v e n u e a n d a s s e t v o l a t i i i t i e s . f i g u r e s h o w s t h a t t h e a v e r a g e r a n k p o s i t i o n o f t h e t r u c k i n g g r o u p s h o w s i m p r o v e m e n t o n a l l d i m e n s i o n s u n t i l i n s e r t f i g u r e h e r e , w i t h r e t u r n o n e q u i t y p o s i t i o n l e a d i n g t h e w a y . t h e o n s e t o f t h e e n e r g y c r i s i s r e v e r s e d t h e i m p r o v i n g t r e n d i n n e t i n c o m e a n d r e t u r n o n e q u i t y , a n d e v e n a d v e r s e l y a f f e c t e d a v e r a g e o p e r a t i n g r e v e n u e p o s i t i o n i n a n d . e v e n t h o u g h r e t u r n o n e q u i t y p o s i t i o n d e t e r i o r a t e d f r o m t o , i t w a s s t i l l f a r b e l o w t h e a v e r a g e r e v e n u e p o s i t i o n , i n d i c a t i n g f a v o r a b l e p e r f o r m a n c e o n t h i s d i m e n s i o n r e l a t i v e t o o t h e r t r a n s p o r t a t i o n f i r m s . r e l a t i v e e m p l o y e e p r o d u c t i v i t y h a s n o t f a r e d s o w e l l , a s s h o w n b y t h e h i g h e m p l o y e e r a n k p o s i t i o n . d e r e g u l a t i o n , p o t e n t i a l a n d a c t u a l ( i n ) , o f t h i s s u b g r o u p l e a d t o a s t a b i l i z i n g o f t h e r e v e n u e a n d a s s e t r a n k p o s i t i o n s a n d w a s f o l l o w e d b y i m p r o v e m e n t s i n f i n a n c i a l p e r f o r m a n c e r a n k i n g s . e . p i p e l i n e s p e r h a p s t h e c l e a r e s t c a s e o f d e r e g u l a t i o n h a v i n g a d i f f e r e n t i a l e f f e c t o n a g r o u p o f t r a n s p o r t a t i o n c o m p a n i e s i s t h a t o f t h e p i p e l i n e s . t h e h o r i z o n t a l l i n e a t r a n k f r o m t o i n f i g u r e m e a n s t h a t i n t h a t p e r i o d p i p e l i n e s w e r e n o t r a n k e d i n s e r t f i g u r e h e r e i n t h e t o p f i f t y t r a n s p o r t a t i o n f i r m s . w h e n t h e n a t u r a l g a s r e g u l a t o r y a c t o f d e r e g u l a t e d t h e p i p e l i n e s , t h e y q u i c k l y t o o k e n t r e p r e n e u r i a l a d v a n t a g e o f t h e o p p o r t u n i t y t o e x p a n d a n d c o m b i n e . a s a r e s u l t , t h e l a r g e s t o f t h e m o n a v e r a g e j u m p e d f r o m o u t o f t h e r a n k i n g s i n o n e y e a r t o t h e t h e m i d - p o i n t i n t h e r a n k i n g s t h e n e x t y e a r . t h e i r l o w a v e r a g e r a n k i n g b y n u m b e r o f e m p l o y e e s , c o m p a r e d t o a v e r a g e r a n k i n g s o n a l l o t h e r d i m e n s i o n s s h o w s s u b s t a n t i a l r e l a t i v e e m p l o y e e p r o d u c t i v i t y , a s m i g h t b e e x p e c t e d i n a c a p i t a l - i n t e n s i v e b u s i n e s s . t h i s l a t t e r s i t u a t i o n i s i n d i c a t e d b y t h e r e l a t i v e l y h i g h a v e r a g e r a n k i n g b a s e d o n a s s e t s . r e t u r n o n e q u i t y r a n k i n g s p e r f o r m e d s p e c t a c u l a r l y i n t h e f i r s t t h r e e y e a r s a f t e r d e r e g u l a t i o n a n d , l i k e n e t i n c o m e p o s i t i o n , b e g a n t o g r a d u a l l y w o r s e n . f . c o m p a r i s o n a n d i m p l i c a t i o n s t h e k e y d e r e g u i a t o r y e v e n t s i n t h e t r a n s p o r t a t i o n i n d u s t r y we r e ) t h e n a t u r a l g a s d e r e g u i a t o r y a c t o f , ) t h e r a i l r o a d r e v i t a l i z a t i o n a n d r e g u l a t o r y r e f o r m a c t o f ) t h e a i r l i n e d e r e g u l a t i o n a c t o f , a n ) t h e m o t o r c a r r i e r a c t o f . ( t h e e f f e c t s o f t h e e n d o f c a b c o n t r o l s o v e r a i r l i n e r a t e s i n a r e t o o r e c e n t t o b e e v a l u a t e d . ) w h i l e t h e s h i f t i n t h e r a n k p e r f o r m a n c e o f t h e p i p e l i n e s i n t h e r a n k i n g s c a n b e t r a c e d d i r e c t l y t o d e r e g u l a t i o n i n , t h e s h i f t i n t h e r e l a t i v e f o r t u n e s o f t h e r a i l r o a d s o n o n e h a n d a n d t h e a i r l i n e s a n d t r u c k i n g o n t h e o t h e r i s , o v e r t h e p e r i o d s t u d i e d , o f c o u r s e , d u e t o m o r e t h a n t h e e f f e c t s o f d e r e g u l a t i o n . t h e r a p i d i m p r o v e m e n t i n a i r l i n e t e c h n o l o g y r e l a t i v e t o r a i l r o a d s , t h e s h i f t i n t r a v e l p a t t e r n s , t h e n e a r - c o m p i e t i o n o f t h e f e d e r a l i n t e r s t a t e h i g h w a y s y s t e m , a n d t h e i n c r e a s e i n t h e r e l a t i v e p r o d u c t i o n o f h i g h v a l u e t o w e i g h t p r o d u c t s o n t h e p a r t o f t h e r e s t o f t h e i n d u s t r i a l s e c t o r , h a v e p l a y e d m a j o r r o l e s i n t h e p e r f o r m a n c e s h i f t s n o t e d h e r e . t h e c l e a r e f f e c t s o f d e r e g u l a t i o n i n t h e s e s u b g r o u p s c a n b e s t b e s e e n i n t h e l a s t y e a r s o f t h e p e r i o d s t u d i e d h e r e i n t h e u n c e r t a i n t y i m p o s e d o n t h e t r e n d s g e n e r a t e d b y t h e a f o r e ­ m e n t i o n e d e x t e r n a l f o r c e s . t h a t i s , w i t h o u t d e r e g u i a t o r y a c t s t h e t r e n d s o f a i r l i n e a n d t r u c k i n g i m p r o v e m e n t a n d r a i l r o a d w o r s e n i n g i n p e r f o r m a n c e w o u l d b e e x p e c t e d t o c o n t i n u e . i n t h i s p e r i o d t h e r e i s n o i n d i c a t i o n t h a t t h e r a t e o f t e c h n o l o g i c a l c h a n g e i n c r e a s e d , b u t t h e l e v e l s o f r a n k s h i f t a n d t h e a s s o c i a t e d u n c e r t a i n t i e s i n c r e a s e s u b s t a n t i a l l y . t h e s e l a t t e r s h o w t h e c l e a r e f f e c t s o f t h e t u r b u l e n c e b r o u g h t a b o u t b y d e r e g u l a t i o n . t h u s , f o r t h e s e t h r e e g r o u p s , t h e e f f e c t s o f d e r e g u l a t i o n a s r e v e a l e d b y t h e m e t h o d o l o g y e m p l o y e d h e r e d o n o t s o m u c h a f f e c t t h e r e l a t i v e p o s i t i o n s o f t h e s u b - g r o u p s a s a w h o l e , b u t d o a f f e c t i n d u s t r y v o l a t i l i t y a n d w i t h i n - g r o u p p o s i t i o n s o f i n d i v i d u a l f i r m s . t h a t t h i s i s t h e c a s e w i l l b e s e e n m o r e c l e a r l y i n t h e e n s u i n g a n a l y s i s . v . a n a l y s i s of i n d i v i d u a l f i r m s h a v i n g e s t a b l i s h e d i n d u s t r y a n d s u b g r o u p p a t t e r n s o f b e h a v i o r d u r i n g t h e p e r i o d o f d e r e g u l a t i o n , i t i s n o w p o s s i b l e t o u s e t h e r a n k a n a l y s i s m e t h o d o l o g y t o a n a l y z e i n d i v i d u a l f i r m s o n a c o m p a r a t i v e b a s i s t o e x a m i n e f i r m - l e v e l r e s p o n s e s t o d e r e g u l a t i o n . t h e t r a n s f o r m a t i o n t o o r d i n a l d a t a a l s o s u p p r e s s e s s h o r t - t e r m n o i s e i n f i r m b e h a v i o r . t h e c o m p a r i s o n a t t h e f i r m l e v e l c a n be m a d e t o b o t h t h e i n d u s t r y l e v e l a n d t h e s u b - i n d u s t r y l e v e l , w i t h s t r a t e g i c e l e m e n t s b e i n g i d e n t i f i e d i n b o t h c o n t e x t s . we t u r n n o w t o a n e x a m i n a t i o n o f t h e r a n k p e r f o r m a n c e o f t wo r a i l r o a d c o m p a n i e s , t h r e e t r u c k i n g f i r m s , a n d f i v e i n d i v i d u a l a i r l i n e s . t h e s e f i r m s w i l l b e e x a m i n e d i n t h e c o n t e x t o f t h e i r p e r f o r m a n c e r e l a t i v e t o a l l o t h e r l a r g e t r a n s p o r t a t i o n c o m p a n i e s . a . r a i l r o a d s t wo d o m i n a n t p a t t e r n s e m e r g e i n t h e a n a l y s i s o f i n d i v i d u a l r a i l r o a d f i r m r a n k b e h a v i o r . t h e m o s t - f o l l o w e d s t r a t e g y i n t h i s i n d u s t r y o v e r t h e p a s t q u a r t e r c e n t u r y w a s t o s t a y p r e d o m i n a n t l y i n t h e r a i l r o a d b u s i n e s s a n d g r o w h o r i z o n t a l l y b y a b s o r b i n g o t h e r f i r m s , o r t o b e a b s o r b e d . a s e c o n d s t r a t e g y w a s t o k e e p t h e r a i l r o a d b u s i n e s s a s a b a s e , b u t t o d i v e r s i f y i n t o o t h e r b u s i n e s s e s . t h e t wo r a i l r o a d c o m p a n i e s a n a l y z e d b e l o w a r e r e p r e s e n t a t i v e o f t h e s e t wo s t r a t e g i e s . . c h i c a g o - m i i w a u k e e r a i l r o a d o f t h e t wo d o m i n a n t p a t t e r n s e x h i b i t e d b y r a i l r o a d c o m p a n i e s o v e r t h e p a s t q u a r t e r c e n t u r y , t h e c h i c a g o - m i i w a u k e e p a t t e r n o f r a n k b e h a v i o r e x e m p l i f i e s t h e f i r m t h a t s t a y e d l a r g e l y i n t h e r a i l r o a d b u s i n e s s . a s f i g u r e d e m o n s t r a t e s , r e t u r n o n e q u i t y i n s e r t f i g u r e h e r e p o s i t i o n l e a d s t h e p a t t e r n o f w o r s e n i n g r a n k p o s i t i o n s . o p e r a t i n g r e v e n u e s h o w s a r e l a t i v e l y s t e a d y d e c l i n e i n r a n k p o s i t i o n , w i t h r a p i d w o r s e n i n g i n t h e p e r i o d f r o m t o , w h e n i t l e v e l s o f f . b o t h a s s e t a n d e m p l o y e e p o s i t i o n s l i e b e l o w t h e o t h e r r a n k p o s i t i o n s , i n d i c a t i n g r e l a t i v e l y p o o r p r o d u c t i v i t y o n b o t h h u ma n f a c t o r s a n d c a p i t a l . n e t i n c o m e p o s i t i o n f o l l o w s r e t u r n o n e q u i t y a n d d r o p s f r o m t h e r a n k i n g s i n . . s o u t h e r n p a c i f i c r a i l r o a d t h e s e c o n d d o m i n a n t r a n k p a t t e r n e x h i b i t e d b y r a i l r o a d c o m p a n i e s i n t h e p e r i o d s t u d i e d i s i l l u s t r a t e d b y s o u t h e r n p a c i f i c ' s r a n k p o s i t i o n s ( f i g u r e ) . s o u t h e r n p a c i f i c , l i k e i n s e r t f i g u r e h e r e s a n t a f e i n d u s t r i e s , r i o g r a n d e i n d u s t r i e s a n d o t h e r s , d i v e r s i f i e d a w a y f r o m t h e r a i l r o a d b u s i n e s s , b u t , o f c o u r s e , s t i l l d e r i v e d b e t t e r t h a n f i f t y p e r c e n t o f i t s o p e r a t i n g r e v e n u e f r o m t r a n s p o r t a t i o n . f o r s o u t h e r n p a c i f i c a n d t h o s e l i k e i t , r e t u r n o n e q u i t y r a n k i s b y i t s e l f , w o r s e n i n g o v e r t h e p e r i o d i n a c y c l i c f a s h i o n , a n d mo r e p o o r l y p o s i t i o n e d t h a n t h e r a n k s o n a l l o t h e r d i m e n s i o n s . a l l o t h e r d i m e n s i o n s a r e c o m p a r a b l y r a n k e d u n t i l a g r a d u a l d i v e r g e n c e a n d s l i g h t w o r s e n i n g i n p o s i t i o n t a k e s p l a c e i n t h e l a s t t w e l v e t o f i f t e e n y e a r s . t h e m e r g e r i n d r o p p e d s o u t h e r n p a c i f i c a s a n i n d i v i d u a l e n t i t y f r o m t h e r a n k i n g s . b . t r u c k i n g a n a l y s i s o f t h e r a n k b e h a v i o r o f t h e t r u c k i n g i n d u s t r y y i e l d e d n o s t r a t e g y g r o u p i n g s s i m i l a r t o t h o s e f o u n d i n t h e r a i l r o a d i n d u s t r y . a p a t t e r n d i d , h o w e v e r , e m e r g e i n t h a t s u c c e s s f u l t r u c k i n g f i r m s w e r e f o u n d t o h a v e b r o u g h t , o r t o b e i n t h e p r o c e s s o f b r i n g i n g t h e i r r a n k p o s i t i o n s o n t h e v a r i o u s d i m e n s i o n s m e a s u r e d i n t o a g r e e m e n t . t h a t i s , i f a s u c c e s s f u l t r u c k i n g f i r m w a s i n t h e i * h p o s i t i o n i n t e r m s o f r e v e n u e i n , i t s r a n k s o n t h e o t h e r d i m e n s i o n s c w i t h t h e e x c e p t i o n o f a s s e t s , w h i c h w e r e a l w a y s l o w e r r a n k e d ) w e r e l i k e l y t o b e n e a r t h e i * ^ p o s i t i o n a l s o . s i n c e t h e f i r m s i n t h e t o p f i f t y a r e t h e r e b e c a u s e o f t h e i r o p e r a t i n g r e v e n u e s i z e , t h e i n t e r p r e t a t i o n o f t h i s b e h a v i o r i s t h a t t h e m a n a g e r s o f t h e s e f i r m s r e s p o n d e d t o t h e u n c e r t a i n t y i n t h e i r e n v i r o n m e n t b y r e d u c i n g t h e i r s t r a t e g i c o p t i o n s a n d t h e s c o p e o f t h e i r f i r m ’ s a c t i v i t i e s t o b e p r o p o r t i o n a l t o t h e i r r e v e n u e p o s i t i o n . t h i s i m p l i e s t h a t t h e f i r m e s t a b l i s h e d a b a l a n c e d p o s i t i o n c v i s a v i s o t h e r l a r g e t r a n s p o r t a t i o n f i r m s ) t h a t w o u l d a l l o w m a n a g e m e n t t o b e t t e r c o p e w i t h t h e e n v i r o n m e n t a l a n d i n d u s t r y u n c e r t a i n t y . t h e t h r e e f i r m s s e l e c t e d a l l e x h i b i t t h i s b e h a v i o r a t s o m e t i m e i n t h e p e r i o d e x a m i n e d . c o n s o l i d a t e d f r e i g h t w a y s a n d r o a d w a y e x p r e s s w e r e s e l e c t e d b e c a u s e t h e y r e p r e s e n t m a i n - s t r e a m t r u c k i n g f i r m s , w h i l e u n i t e d p a r c e l s e r v i c e w a s i n c l u d e d t o s h o w t h e e f f e c t s o f b e i n g i n a h i g h - g r o w t h s e g m e n t o f t r u c k i n g . . c o n s o l i d a t e d f r e i g h t w a y s c o n s o l i d a t e d f r e i g h t w a y s ’ i m p r o v e m e n t i n r a n k p e r f o r m a n c e ( f i g u r e ) e x c e e d s t h e i n d u s t r y a s a w h o l e o n a l l d i m e n s i o n s e x c e p t r e t u r n o n e q u i t y i n s i x y e a r s a n d n e t i n c o m e i n o n e y e a r . t h i s f i r m s h o w s t h e h i g h a s s e t p r o d u c t i v i t y a s s o c i a t e d w i t h t r u c k i n g a n d , e x c e p t f o r p o o r r e t u r n s i n a n d , t h e r e t u r n o n e q u i t y p o s i t i o n i s e x c e l l e n t u n t i l . t h e e n e r g y f t * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * i n s e r t f i g u r e h e r e c r i s i s f o r c e d a w e a k e n i n g i n r e t u r n o n e q u i t y a n d n e t i n c o m e r a n k s f o r t wo y e a r s , b u t b o t h r e c o v e r e d s o m e w h a t i n . o p e r a t i n g r e v e n u e f o r c o n s o l i d a t e d i m p r o v e s r a t h e r s t e a d i l y u n t i i w h e n i t d e c l i n e s i n r a n k f o r o n e y e a r a n d t h e n r e s u m e s i t s t r e n d . w h i l e n o t e x p e r i e n c i n g a n y g r e a t r e l a t i v e e m p l o y e e p r o d u c t i v i t y , c o n s o l i d a t e d k e e p s e m p l o y e e p o s i t i o n i n l i n e w i t h r e v e n u e p o s i t i o n . t h e d e r e g u i a t o r y y e a r o f s a w a w o r s e n i n g o f r e t u r n o n e q u i t y a n d n e t i n c o m e p o s i t i o n s . t h e l a t t e r r a n k i n g w a s b r o u g h t i n t o l i n e t h e n e x t y e a r , b u t f o r t h e f o r m e r t wo v e r y b a d y e a r s f o l l o w e d . t h e y e a r s s i n c e d e r e g u l a t i o n h a v e s e e n m a n a g e m e n t i m p r o v e r e t u r n o n e q u i t y a n d b r i n g n e t i n c o m e , o p e r a t i n g r e v e n u e a n d n u m b e r o f e m p l o y e e s i n t o n e a r - i d e n t i c a l p o s i t i o n s , a s w a s m e n t i o n e d a b o v e . . r o a d w a y e x p r e s s r o a d w a y e x p r e s s a p p e a r e d i n t h e t o p f i f t y r e v e n u e r a n k i n g s i n , a s s h o w n i n f i g u r e . t h e o u t s t a n d i n g r e t u r n o n e q u i t y p o s i t i o n o f t h i s f i r m i n i t s f i r s t f o u r y e a r s i n t h e r a n k i n g s i s e v i d e n t . h o w e v e r , s i n c e t h i s p o s i t i o n h a s g r a d u a l l y e r o d e d . i n s e r t f i g u r e h e r e t h e p a t t e r n o f r a n k b e h a v i o r i s m u c h s m o o t h e r f o r r o a d w a y t h a n i t w a s f o r c o n s o l i d a t e d ( f i g u r e ) . o n l y a s l i g h t w o r s e n i n g i n a l l b u t a s s e t p o s i t i o n i s s h o w n d u r i n g t h e e n e r g y s h o r t a g e . r o a d w a y ' s m a n a g e m e n t b r o u g h t r a n k p o s i t i o n o n a l t d i m e n s i o n s e x c e p t a s s e t s i n t o a l i g n m e n t t h r o u g h t h e ' s . w h e n d e r e g u l a t i o n l e g i s l a t i o n w a s p a s s e d i n , t h e f i r m w a s i n g o o d p o s i t i o n a n d g o o d s h a p e t o t a k e a d v a n t a g e o f t h e s i t u a t i o n . . u n i t e d p a r c e l s e r v i c e c o n s o l i d a t e d f r e i g h t w a y s a n d r o a d w a y e x p r e s s a r e i n r e l a t i v e l y t h e s a m e s e g m e n t o f t h e t r a n s p o r t a t i o n b u s i n e s s . u n i t e d p a r c e l s e r v i c e p a r t i c i p a t e s i n a d i f f e r e n t s t r a t e g i c g r o u p a n d i t s r a n k p e r f o r m a n c e ( f i g u r e ) i c o n s e q u e n t l y q u i t e d i f f e r e n t . o u t o f i n s e r t f i g u r e h e r e t h e t o p f i f t y t r a n s p o r t a t i o n f i r m s u n t i l , u p s e n t e r e d a t t h e e i g h t h p o s i t i o n i n t e r m s o f o p e r a t i n g r e v e n u e a n d i n t h e f i r s t p o s i t i o n i n t e r m s o f n u m b e r o f e m p l o y e e s . w h i l e t h e r e v e n u e p o s i t i o n h a s i m p r o v e d o v e r t h e l a s t d e c a d e o f t h e s t u d y , t h e r a n k b y n u m b e r o f e m p l o y e e s c o n t i n u e s t o s h o w t h e l a b o r - i n t e n s i v e s t r a t e g y o f u p s . t h e u n c e r t a i n t y c a u s e d b y d e r e g u l a t i o n d o e s n o t s h o w u p i n t h e r a n k p o s i t i o n s o f u p s . t h e g r o w t h o f i t s s e g m e n t o f t h e b u s i n e s s h a s b e e n s u f f i c i e n t t o s wa mp n o i s e c a u s e d b y u n c e r t a i n t y , a n d u p s h a s m a n a g e d t h i s g r o w t h w e l l - a t l e a s t i n t e r m s o f i t s r a n k p o s i t i o n s . t h e n e a r i y - i d e n t i c a i r a n k p o s i t i o n s o f r e v e n u e , n e t i n c o m e , a n d r e t u r n o n e q u i t y i n t h e l a s t t wo y e a r s c o u p l e d w i t h t h e v e r y h i g h e m p l o y e e r a n k p o s i t i o n , i n d i c a t e a w e l l - b a l a n c e d , m a t u r e f i r m w i t h a s e r v i c e s t r a t e g y . c . a i r l i n e s i n t h e p r e v i o u s t wo s e c t i o n we h a v e e x a m i n e d s e l e c t e d r a i l r o a d a n d t r u c k i n g f i r m s i n t e r m s o f t h e i r p e r f o r m a n c e r e l a t i v e t o t h e o t h e r t o p f i f t y t r a n s p o r t a t i o n f i r m s . i n t h i s s e c t i o n we w i l l e x a m i n e f i v e a i r l i n e f i r m s o n t h a t b a s i s . t h e f i v e a i r l i n e s a n a l y z e d , u n i t e d , n o r t h w e s t , d e l t a , a m e r i c a n a n d p a n a m e r i c a n w e r e c h o s e n b e c a u s e o f t h e d i f f e r i n g c h a r a c t e r i s t i c s o f t h e i r r a n k p e r f o r m a n c e a n d t h e e f f e c t s o f i m p e n d i n g a n d a c t u a l d e r e g u l a t i o n o n t h a t p e r f o r m a n c e . . u n i t e d a i r l i n e s f i g u r e s h o w s , f o r e x a m p l e , t h a t i n r e l a t i o n t o t h e f i g u r e h e r e t o p f i f t y t r a n s p o r t a t i o n f i r m s , u n i t e d a i r l i n e s h a s b e e n a l e a d e r i n t h e a i r l i n e s u b g r o u p ’ s i m p r o v e m e n t i n o p e r a t i n g r e v e n u e a n d a s s e t r a n k i n g s , a n d t h a t u n i t e d f o l l o w s t h e s u b g r o u p p a t t e r n o f s t a b i l i z i n g t h e s e t wo p e r f o r m a n c e d i m e n s i o n s i n t h e p e r i o d a f t e r . u n l i k e t h e o t h e r t wo a i r l i n e s a n a l y z e d h e r e , u n i t e d e n g a g e d i n a c q u i s i t i o n s o u t s i d e t h e a i r l i n e i n d u s t r y , t o t h e p o i n t w h e r e % o f i t ' s r e v e n u e s w e r e n o n - a i r l i n e i n . i n t h e p e r i o d f r o m t o u n i t e d h a d m o d e r a t e f l u c t u a t i o n s i n r e t u r n o n e q u i t y a n d n e t i n c o m e . b e g i n n i n g i n , w h e n w e s t e r n i n t e r n a t i o n a l h o t e l s w e r e a c q u i r e d c o n c u r r e n t l y w i t h l o s s o f k e y h a w a i i a n r o u t e s ( b y r n e s , p. ) u n i t e d e x p e r i e n c e d w i d e f l u c t u a t i o n s i n r e t u r n o n e q u i t y a n d n e t i n c o m e . t h e s e c o n d l a r g e a d v e r s e s h i f t i n t h e s e t wo m e a s u r e s c o i n c i d e s w i t h t h e a c q u i s i t i o n o f g a b i n . a n i m p r o v e m e n t i n b o t h m e a s u r e s c o i n c i d e d w i t h a c h a n g e i n t h e i n v e s t m e n t t a x c r e d i t l a w s i n ( b y r n e s , p . ) t h e t h i r d m a j o r w o r s e n i n g c o i n c i d e d w i t h t h e f o r m a l i m p l e m e n t a t i o n o f d e r e g u l a t i o n i n . b y r n e s ( , p . ) s t a t e s t h a t u n i t e d w a s o n e o f t h e a i r l i n e s t h a t s a w i t s p r o s p e c t s i m p r o v e w i t h d e r e g u l a t i o n . i n f a c t , a c c o r d i n g t o t h e m e t h o d o l o g y e m p l o y e d h e r e , u n i t e d ' s p e r f o r m a n c e d i d n o t b e g i n t o i m p r o v e u n t i l , a n d d i d n o t a p p r o a c h p r e - l e v e l s o f n e t i n c o m e p e r f o r m a n c e u n t i l . e v e n t h e n , r e t u r n o n e q u i t y p o s i t i o n w a s s t i l l p o o r . . no r t hwe s t a i r l i n e s n o r t h w e s t a i r l i n e s , o n t h e o t h e r h a n d , a s s h o w n i n f i g u r e , h a s ma d e g r e a t e r g a i n s i n a s s e t a n d r e v e n u e r a n k i n g s r e l a t i v e i n s e r t f i g u r e h e r e a * # # * * # * * * * # * * * * * * * : * * * * * * * * * * * * * * * * * * * * * * # ; * : * * # * * * * * * * # ; * # * * * t o t h e t o p t r a n s p o r t a t i o n f i r m s , a n d i n t h e p e r i o d f r o m t o b r o u g h t t h o s e t wo r a n k i n g s t o n e a r e q u a l i t y . i n t h e l a s t f i v e y e a r s o f t h e s t u d y , r e v e n u e p o s i t i o n h a s i m p r o v e d r e l a t i v e t o a s s e t p o s i t i o n , s i g n a l i n g i m p r o v e d r e l a t i v e u s e o f a s s e t s o n t h e p a r t o f n o r t h w e s t ' s m a n a g e m e n t . i n t h e p e r i o d u p t o , n o r t h w e s t h a d a n e x c e l l e n t r e t u r n o n e q u i t y p o s i t i o n a n d u n t i l t h e l a s t f e w y e a r s o f t h e d a t a h a s e n j o y e d b e t t e r n e t i n c o m e a n d r e t u r n o n e q u i t y r a n k i n g s a n d l o w e r f l u c t u a t i o n s i n t h o s e r a n k i n g s t h a n h a d u n i t e d a i r l i n e s . r e l a t i v e t o t h e t r a n s p o r t a t i o n i n d u s t r y , n o r t h w e s t s h o w s g o o d r e l a t i v e e m p l o y e e p r o d u c t i v i t y a s i t s a v e r a g e r a n k o n t h i s d i m e n s i o n i s w o r s e t h a n i t s r e v e n u e p o s i t i o n i n a l l p e r i o d s w h e r e t h e r e i s d a t a f o r b o t h . t o h i g h l i g h t t h e d i f f e r e n t v i e w t h a t o u r m e t h o d o l o g y p r o v i d e s c o n s i d e r s t a t e m e n t s m a d e b y b y r n e s ( ) a b o u t n o r t h w e s t b a s e d o n c a r d i n a l d a t a a n a l y s i s : " a p r o f i t a b l e , s i o w - g r o w t h s t r a t e g y s u c h a s n o r t h w e s t ' s . " ( p . ) a n d " d e l t a a n d n o r t h w e s t p r o s p e r e d t h r o u g h o u t m o s t o f t h e d e r e g u i a t o r y t r a n s i t i o n p e r i o d . " ( p . ) . i n f a c t , f i g u r e s h o w s t h a t b e t w e e n a n d n o r t h w e s t h a d n o r e l a t i v e g r o w t h i n t h e p e r i o d , a n d w o r s e n i n g p r o f i t a b i l i t y f r o m t o . t h e a b i l i t y o f t h e a n a l y s i s b a s e d o n r a n k p o s i t i o n s t o e l i m i n a t e s h o r t - t e r m n o i s e f r o m b u s i n e s s c y c l e s a n d i n f l a t i o n , a n d s h o w j u s t t h o s e e f f e c t s t h a t a r e d i f f e r e n t i a l , y i e l d s a v i e w t h a t s u g g e s t s a d i f f e r e n t i n t e r p r e t a t i o n , t h a n p r o v i d e d b y s t a n d a r d a n a l y s i s . . d e l t a a i r l i n e s f i g u r e s h o w s t h a t , l i k e n o r t h w e s t , d e l t a a i r l i n e s e x p e r i e n c e d s t e a d y i m p r o v e m e n t r e l a t i v e t o o t h e r t r a n s p o r t a t i o n f i r m s o n m o s t r a n k e d d i m e n s i o n s f r o m t o . a s s e t a n d e m p l o y e e p o s i t i o n s p r i o r t o i n d i c a t e r e l a t i v e h i g h i n s e r t f i g u r e h e r e p r o d u c t i v i t y o f t h e s e f a c t o r s . r e t u r n o n e q u i t y p o s i t i o n i s e x c e l l e n t u n t i l a n d n e t i n c o m e p o s i t i o n i s f a v o r a b l e u n t i l , b u t a s d e r e g u l a t i o n t a k e s e f f e c t a n d t h e i n d u s t r y b e c o m e s mo r e t u r b u l e n t , r e t u r n o n e q u i t y a n d n e t i n c o m e p o s i t i o n s w o r s e n f o r s e v e r a l y e a r s a n d i m p r o v e o n l y i n t h e l a s t y e a r e x a m i n e d . t h e q u o t a t i o n f r o m b y r n e s c i t e d j u s t a b o v e c o n c e r n i n g d e l t a ' s " p r o s p e r i t y ' d u r i n g d e r e g u l a t i o n i s c o n t r a d i c e d b y t h i s p a t t e r n . t h e e s s e n t i a l p o i n t h e r e i s t h a t d e l t a w a s p o s i t i o n e d i n t e r m s o f i t s r a n k p o s i t i o n s b e i n g a l l i g n e d i n t h e l a t e s e v e n t i e s s o t h a t e v e n t h o u g h p r o f i t a b i l i t y f e l l a s d e r e g u l a t i o n w e n t i n t o e f f e c t , t h e a i r l i n e w a s a b l e t o q u i c k l y r e c o v e r b y . . ame r i c a n a i r l i n e s a t t h e o u t s e t o f t h e p e r i o d s t u d i e d h e r e , a m e r i c a n a i r l i n e s a l r e a d y h a d a w e l l - e s t a b l i s h e d p o s i t i o n i n t h e t r a n s p o r t a t i o n i n d u s t r y ( f i g u r e ) . e x c e p t f o r a s u b s t a n t i a l w o r s e n i n g i n r e t u r n o n e q u i t y a n d n e t i n c o m e p o s i t i o n s i n t h e e a r l y s i x t i e s , ^ ̂ ^ ̂ ̂ ̂ ̂ u* ̂ ̂ ̂ ̂ ̂ ̂ ̂ ̂ ̂ ̂ ̂ ^ ̂ ̂ ̂ ̂ ̂ ̂ ̂ ̂ ̂ ̂ ̂ ̂ ̂ ̂ ̂ ^ ̂ ̂ ̂ ̂ ^ ̂ ̂ ̂ ̂ ̂ ̂ ^ a m ^ ^ * a a a ^ ^ m a a a a a a a a a a m m a a m m a a m m a ^ m m a ^ m m a ^ a a a a a m a a a ^ m m a i n s e r t f i g u r e h e r e t h o s e p o s i t i o n s i m p r o v e d u n t i l . i n t h e p e r i o d - , a m e r i c a n e m b a r k e d o n a s e r i e s o f d i v e r s i f i c a t i o n m o v e s t h a t a r e g r a p h i c a l l y r e f l e c t e d i n t h e p o o r r e t u r n o n e q u i t y a n d n e t i n c o m e p o s i t i o n s i n t h o s e y e a r s . i m p r o v e m e n t i n t h e s e p o s i t i o n s i s n o t s e e n u n t i l a m e r i c a n r e d u c e d i t s d i v e r s i f i c a t i o n i n t h e l a s t p a r t o f t h e s e v e n t i e s . t h e o t h e r t h r e e d i m e n s i o n s o f p e r f o r m a n c e i m p r o v e s l i g h t l y o r r e m a i n t h e s a m e u n t i l , a t t h e e n d o f t h e p e r i o d , t h e y a r e g e n e r a l l y i n a g r e e m e n t i n t e r m s o f t h e i r r a n k p o s i t i o n , i n d i c a t i n g t h a t m a n a g e m e n t r e s p o n d e d t o t h e u n c e r t a i n t y o f d e r e g u l a t i o n b y b a l a n c i n g m a r k e t p e r f o r m a n c e a n d r e s o u r c e u t i l i z a t i o n . w i t h t h e o n s e t o f d e r e g u l a t i o n ame r i c a n ' s r e t u r n o n e q u i t y a n d n e t i n c o m e p o s i t i o n s , w h i c h h a d i m p r o v e d m a r k e d l y , w o r s e n e d i n t h e p o s t - d e r e g u a t i o n p e r i o d ( a s w a s t h e c a s e f o r t h e p r e c e d i n g a i r l i n e s e x a m i n e d ) b u t w a s b r o u g h t b a c k i n a n d . t o s h o w h o w i n f o r m a t i o n g a i n e d t h r o u g h r a n k a n a l y s i s c o m p l e m e n t s t r a d i t i o n a l a n a l y s i s , c o n s i d e r b y r n e s s t a t e m e n t ( , p . ) t h a t “ a m e r i c a n ' s e a r n i n g s v a r i a n c e w a s v e r y s i m i l a r t o , o r l o w e r t h a n t h o s e o f t h e f o u r n o n d i v e r s i f y i n g f i r m s , y e t a m e r i c a n d i v e r s i f i e d a c t i v e l y , i n t h e p e r i o d i m m e d i a t e l y p r e c e d i n g a m e r i c a n ' s m a j o r e n t r y i n t o t h e h o t e l b u s i n e s s , i t r a n k e d s e c o n d i n e a r n i n g s s t a b i l i t y . i n t h e f o l l o w i n g p e r i o d s , s p a n n i n g t o , i t h a d o n l y m o d e r a t e v a r i a n c e , b u t i t s u b s t a n t i a l l y i n c r e a s e d i d i v e r s i f i c a t i o n . t h e r e f o r e , e a r n i n g s v a r i a n c e d o e s n o t s e e m t o h a v e b e e n a n i m p o r t a n t m o t i v a t i o n f o r a m e r i c a n ’ s d i v e r s i f i c a t i o n . " f i g u r e i n d i c a t e s t h a t i n t h e p r e - p e r i o d a m e r i c a n d i d h a v e l o w v a r i a n c e o n r e t u r n o n e q u i t y p o s i t i o n , b u t a t w o r s e ( a n d w o r s e n i n g ) r a n k p o s i t i o n s t h a n a i r l i n e s s u c h a s d e l t a a n d n o r t h w e s t ( f i g u r e s a n d ) . i n t h e p o s t - p e r i o d , a m e r i c a n d i d h a v e m o d e r a t e v a r i a n c e i n r o e , b u t a t m u c h w o r s e ( b u t i m p r o v i n g ) r a n k i n g s t h a n t h e n o n d i v e r s i f y i n g a i r l i n e s . t h u s b y r n e s i s c o r r e c t a s f a r a s h e g o e s : t h e r e s t o f t h e s t o r y i s t h a t w o r s e n i n g e a r n i n g s p o s i t i o n p r o b a b l y w a s a n i m p o r t a n t m o t i v a t i n g f a c t o r f o r d i v e r s i f i c a t i o n a n d d e s i r e f o r i m p r o v e m e n t i n t h a t p o s i t i o n a n d n e t i n c o m e p o s i t i o n p r o b a b l y f u e l e d f u r t h e r d i v e r s i f i c a t i o n . . p a n ame r i c a n t h e r a n k p o s i t i o n s o f p a n a m e r i c a n o v e r t i m e i n r e l a t i o n t o t h e t o p f i f t y t r a n s p o r t a t i o n c o m p a n i e s ( f i g u r e ) p r o v i d e s a g r a p h i c i l l u s t r a t i o n o f t h e i m p a c t s o f d e r e g u l a t i o n a n d m a n a g e m e n t ’ s r e a c t i o n . up u n t i l p a n a m e r i c a n w a s m a k i n g r a n k p o s i t i o n g a i n s o n a l l d i m e n s i o n s . w h e n t h e c i v i l a e r o n a u t i c s b o a r d m a d e t h e t r a n s p a c i f i c a w a r d s i n t h a t y e a r a n d p a n a m e r i c a n d i v e r s i f i e d , t h e i m p a c t s o n r e t u r n o n e q u i t y a n d n e t i n c o m e i n s e r t f i g u r e h e r e p o s i t i o n s w e r e i mme d i a t e a n d d i s a s t r o u s a s t h e g r a p h s h o w s . ( i n c o n t r a s t , b y r n e s ( , p . ) , r e f e r r i n g t o a b s o l u t e l e v e l s o f r e t u r n s , r e p o r t s " p a n a m e r i c a n ' s d i v e r s i f i c a t i o n r a i s e d i t s r e t u r n s , w h i c h b e n e f i t e d b o t h s o c i e t y a n d t h e a i r l i n e . " ) t h e o p e r a t i n g r e v e n u e , a s s e t , a n d e m p l o y e e p o s i t i o n s b e g a n t o s l o w l y e r o d e , t o b e r e v e r s e d o n l y s l i g h t l y a n d t e m p o r a r i l y i n w i t h t h e p u r c h a s e o f n a t i o n a l a i r l i n e s . t h e o t h e r t wo p e r f o r m a n c e d i m e n s i o n s d i d n o t i m p r o v e u n t i l t h e c o m p a n y m a d e a s u b s t a n t i a l s a l e o f a s s e t s i n , b u t t h e e f f e c t w a s o n l y t e m p o r a r y . t h e p u r c h a s e o f n a t i o n a l a c c e l e r a t e d t h e d e c l i n e i n n e t i n c o m e r a n k , t o b e f o l l o w e d b y s i m i l a r b e h a v i o r i n r e t u r n o n e q u i t y r a n k . d. i m p l i c a t i o n s a s w a s h y p o t h e s i z e d a t t h e c o n c l u s i o n o f t h e l a s t s e c t i o n o f t h i s p a p e r , a n a l y s i s o f i n d i v i d u a l f i r m s i n t h e r a i l r o a d , t r u c k i n g a n d a i r l i n e i n d u s t r i e s r e v e a l s t h a t d e r e g u l a t i o n , w h i l e n o t a l t e r i n g t h e c h a n g e i n r e l a t i v e p o s i t i o n s o f t h e v a r i o u s m o d e s o f t r a n s p o r t a t i o n ( w i t h t h e e x c e p t i o n o f p i p e l i n e s ) , d o e s a l t e r t h e p o s i t i o n s o f i n d i v i d u a l f i r m s w i t h i n t h e m o d e g r o u p s . t h e a n a l y s i s s h o w e d s t r i k i n g l y d i f f e r e n t p a t t e r n s o f r e s p o n s e t o t h e c h a n g i n g c o n d i t i o n s i n t h e t r a n s p o r t a t i o n i n d u s t r y o v e r t h e p a s t q u a r t e r - c e n t u r y . i n t h e a i r l i n e i n d u s t r y , a t t e m p t s a t d i v e r s i f i c a t i o n i n t h e l a t e s i x t i e s a n d e a r l y s e v e n t i e s t o b u f f e r t h e p o s s i b l e e f f e c t s o f i m p e n d i n g d e r e g u l a t i o n l e a d t h o s e a i r l i n e s f o l l o w i n g t h i s s t r a t e g y t o d e s t a b i l i z e t h e i r r e l a t i v e p r o f i t a b i l i t y . w h e n d e r e g u l a t i o n b e c a m e a f a c t i n t h e l a t e s e v e n t i e s , a l l a i r l i n e s , r e g a r d l e s s o f t h e s t r a t e g y a d o p t e d , h a d t h e i r p r o f i t a b i l i t y d e s t a b i l i z e d . t h e r a n k d a t a p r e s e n t e d h e r e i m p l i e s t h a t t h e m a n a g e r i a l r e s p o n s e t o d e r e g u l a t i o n i n t h i s i n d u s t r y w a s t o a t t emp t t o m a i n t a i n m a r k e t s h a r e a n d a s s e t r a n k s t a b i l i t y . t h e e v i d e n c e f u r t h e r i n d i c a t e s t h a t s t a b i l i t y i n m a r k e t s h a r e a n d e v i d e n c e f u r t h e r i n d i c a t e s t h a t s t a b i l i t y i n m a r k e t s h a r e a n d a s s e t s w a s p a i d f o r b y i n s t a b i l i t y i n r e t u r n o n e q u i t y a n d n e t i n c o me p o s i t i o n s . r e c e n t d a t a i m p l y t h a t w h i l e i n s t a b i l i t y o f t h i s t y p e s t i l l e x i s t s i n t h i n d u s t r y , s o m e f i r m s a r e b r i n g i n g t h e i r p e r f o r m a n c e i n t o a b a l a n c e d p o s i t i o n a n d h a v e p r e p a r e d t o c o p e i n t h e n e w e n v i r o n m e n t . t h i s l a s t - m e n t i o n e d s i t u a t i o n i s a l s o t h e c a s e f o r t h e f i r m s i n t h e t r u c k i n g i n d u s t r y . d e r e g u l a t i o n h a s a f f e c t e d t h e r e l a t i v e p r o f i t a b i l i t y o f a n u m b e r o f f i r m s , b u t t h o s e i n f a s t - g r o w i n g m a r k e t n i c h e s , e . g . , u n i t e d p a r c e l s e r v i c e , a n d t h o s e w h o h a v e b a l a n c e d t h e i r p e r f o r m a n c e , e . g . , r o a d w a y , h a v e b e e n a b l e t o m a i n t a i n t h e i r r e l a t i v e p r o f i t a b i l i t y . i n t h e r a i l r o a d i n d u s t r y , o n t h e o t h e r h a n d , i f d e r e g u l a t i o n h a d a n y e f f e c t s , t h e y a r e n o t n o t i c e a b l e i n t h e a n a l y s i s p r e s e n t e d h e r e . i n d i v i d u a l r a i l r o a d c o m p a n i e s c o n t i n u e t h e i r r e l a t i v e d e c l i n e i n p e r f o r m a n c e o n a l l d i m e n s i o n s i n a c o m p a r a t i v e l y s m o o t h f a s h i o n . a p p a r e n t l y t h e m a t u r i t y o f t h e s u b - i n d u s t r y m i t i g a t e s a g a i n s t d i f f e r e n t i a l e f f e c t s d u e t o d e r e g u l a t i o n , a n d e v e n s t r a t e g i c d i f f e r e n c e s s u c h a s d i v e r s i f i c a t i o n o r n o n - d i v e r s i f i c a t i o n d o n o t a p p e a r t o h a v e a s u b s t a n t i a l e f f e c t . v i . c o n c l u s i o n s i n t h i s p a p e r we h a v e p r e s e n t e d a n a n a l y s i s o f t h e i m p a c t s o f d e r e g u l a t i o n o n t h e t r a n s p o r t a t i o n i n d u s t r y i n g e n e r a l a n d t h e r a i l r o a d , t r u c k i n g , a n d a i r l i n e i n d u s t r i e s i n p a r t i c u l a r f r o m a n e w p e r s p e c t i v e . we h a v e e x a m i n e d t h e s i t u a t i o n i n t h e t r a n s p o r t a t i o n i n d u s t r y i n a h i g h l y r e l a t i v i s t i c f a s h i o n b y u s i n g t h e r a n k p o s i t i o n d a t a o f t h e f i r m s i n t h e i n d u s t r y . t h e m u l t i p l e p e r s p e c t i v e s g e n e r a t e d h e r e h a v e r e v e a l e d t h a t t h e p r i m a r y i m p a c t o f d e r e g u l a t i o n a t t h e i n d u s t r y l e v e l h a s a l t e r e d t h e p a t t e r n o f c h a n g e a m o n g t h e m a j o r t r a n s p o r t a t i o n m o d e s o n l y i n t h e c a s e o f p i p e l i n e s , b u t h a s n o t a f f e c t e d t h e r e l a t i o n s a m o n g r a i l r o a d s , a i r l i n e s , a n d t r u c k i n g m o d e s i n a s i m i l a r f a s h i o n . t h e m a j o r i m p a c t o f d e r e g u l a t i o n f o r t h e s e t h r e e m o d a l g r o u p s w a s t o r a i s e t h e l e v e l s o f v o l a t i l i t y a n d u n c e r t a i n t y w i t h i n t h e g r o u p s . t h u s , i m p a c t s o f d e r e g u l a t i o n s h o w m o s t c l e a r l y i n t h e d i f f e r e n t i a l b e h a v i o r o f i n d i v i d u a l f i r m s a s o p p o s e d t o g r o u p s o f f i r m s . a n a l y s i s o f i n d i v i d u a l r a i l r o a d s s h o w e d s i m i l a r r e s u l t s f o r d i f f e r e n t d i v e r s i f i c a t i o n s t r a t e g i e s . a n a l y s i s o f i n d i v i d u a l a i r l i n e s i n d i c a t e d t h a t p r o f i t a b i l i t y w a s h u r t b o t h b y d i v e r s i f i c a t i o n a n d b y d e r e g u l a t i o n , a n d a n a l y s i s o f t r u c k i n g f i r m s s h o w e d t h a t g r o w t h s t r a t e g i e s c o u i d s w a m p t h e e f f e c t s o f d e r e g u l a t i o n . two i n t e r e s t i n g p a t t e r n s t h a t h a v e b e e n n o t e d , b u t n o t f u l l y e x p l a i n e d h e r e , a r e : - d e c l i n e s i n r e t u r n o n e q u i t y p o s i t i o n t e n d t o l e a d t h e d e c l i n e o n a l l o t h e r d i m e n s i o n s f o r g r o u p s o f f i r m s , a n d - t h e b e t t e r m a n a g e d f i r m s t e n d i n t i m e s o f e n v i r o n m e n t a l t u r b u l e n c e t o b r i n g t h e p e r f o r m a n c e r a n k i n g s o n a i l d i m e n s i o n s i n t o a g r e e m e n t , c o n d i t i o n e d o n t h e c a p i t a l i n t e n s i t y o f t h e i n d u s t r y s u b - g r o u p . f u r t h e r s t u d y i s r e q u i r e d t o a s c e r t a i n i f t h e o b s e r v e d r e l a t i o n s h i p s c a n b e g e n e r a l i z e d , p e r h a p s t o t h e p o i n t t h a t t h e y c a n b e u s e d f o r m a n a g e r i a l a n a l y s i s a n d / o r p r e d i c t i o n . a c k n o w l e d g m e n t s t h e a u t h o r w o u l d l i k e t o a c k n o w l e d g e t h e h e l p f u l s u g g e s t i o n s g i v e n b y r i c h a r d b u r t o n a n d b o r g e o b e l a n d t h e s u p p o r t p r o v i d e d b y t h e i c ^ i n s t i t u t e a n d p r o j e c t q u e s t o f t h e u n i v e r s i t y o f t e x a s a t a u s t i n . b i b l i o g r a p h y c l ] a l t s h u l e r , a l a n , c u r r e n t i s s u e s i n t r a n s p o r t a t i o n p o l i c y . l e x i n g t o n b o o k , h e a t h & c o . , l e x i n g t o n , m a s s . , . . ( a n s o f f , i g o r , c o r p o r a t e s t r a t e g y . m c g r a w - h i l l , n e w y o r k , . . ( b o i s j o l y , r u s s e l p . , a n d t h o m a s m. c o r s i , " t h e a f t e r m a t h o f t h e mo t o r c a r r i e r a c t o f : e n t r y , e x i t , a n d m e r g e r , " p r o c e e d i n g s o f t h e r d _ ^ a n n u a l m e e t i n g o f t h e t r a n s d o c_la_t_lo.n. r e s e a r c h . f o r ur n, p p . - , . [ j b y r n e s , j o n a t h a n l . s . , d i v e r s i f i c a t i o n s t r a t e g i e s f o r r e g u l a t e d a n d d e r e g u l a t e d i n d u s t r i e s : l e s s o n s f r o m t h e a r i n e s . l e x i n g t o n b o o k s , l e x i n g t o n , m a s s . , . . ] c a v e s , r i c h a r d e . , a m e r i c a n i n d u s t r y : s t r u c t u r e . c o n d u c t . p e r f o r ma n e e . p r e n t i c e - h a i , e n g l e w o o d c l i f f s , n . j . , . . [ ] c a v e s , d o u g l a s w. , l a u r l t s r. c h r i s t i a n s e n , a n d m i c h a e l w. t r e t h w a y , " u . s . t r u n k a i r c a r r i e r s , - : a m u l t i l a t e r a l c o m p a r i s o n o f t o t a l f a c t o r p r o d u c t i v i t y , " i n p r o d u c t i v i t y m e a s u r e m e n t i n r e g u l a t e d i n d u s t r i e s . c o w i n g , t h o m a s g . , a n d r o d n e y e . s t e v e n s o n ( e d ) , a c a d e m i c p r e s s . . ] c u n n i n g h a m , l . f . , a n d w . r . w o o d , “ d i v e r s i f i c a t i o n i n m a j o r u . s . a i r l i n e s , ' _ t _ _ r _ a n s p o r t a t i o n j o u r n a l . s p r i n g . [ ] d i e w e r t , w. e r w i n , “ t h e t h e o r y o f t o t a l f a c t o r p r o d u c t i v i t y m e a s u r e m e n t i n r e g u l a t e d i n d u s t r i e s , " i n p r o d u c t i v i t y m e a s u r e m e n t i n r e o u e i a t e d i n d u s t r i e s . t h o m a s g. c o w i n g a n d r o d n e y e . s t e v e n s o n ( e d ) , a c a d e m i c p r e s s , . . ] f o r t u n e . t i m e , i n c . - . c ] f r i e d i a e n d e r , a n n f . , a n d r i c h a r d h. s p a d y , f r e i g h t t r a n s p o r t r e g u l a t i o n . t h e m i t p r e s s , c a m b r i d g e , m a s s . , . l i t ] f r u h a n , w. , t h e f i g h t f o r c o m p e t i t i v e a d v a n t a g e : a s t u d y o f t h e u n i t e d s t a t e s d o m e s t i c t r u n k a i r c a r r i e r s , d i v i s i o n o f r e s e a r c h , h a r v a r d u n i v e r s i t y , b o s t o n , m a s s . , . ( h a x , a r n o l d o , a n d n i c h o l a s s . m a j l u f , s t r a t e g i c m a n a g e m e n t : a n i n t e g r a t e d p e r s p e c t i v e . p r e n t i c e - h a i i , e n g l e w o o d c l i f f s , n . j . , . t h u n s a k e r , j a m e s k i r k , “ t h e c h a n g i n g s h a p e o f a m e r i c a ’ s a i r l i n e i n d u s t r y : a n a n a l y s i s o f t h e d e r e g u l a t i o n s t r a t e g i e s o f f i v e a i r l i n e s , " p r o c e e d i n g s o f t h e n d a n n u a l m e e t i n g o f t h e t r a n s p o r t a t i o n r e s e a r c h f o r u m , p p . - , . [ k i m b e r l y , j . r . , " i s s u e s i n t h e d e s i g n o f l o n g i t u d i n a l o r g a n i z a t i o n a l r e s e a r c h , " s o c i o l o g i c a l m e t h o d s a n d r e s e a r c h . v o i . , p p . - , . c k i m b e r l y , j . r . , " d a t a a g g r e g a t i o n i n o r g a n i z a t i o n a l r e s e a r c h : t h e t e m p o r a l d i m e n s i o n , " o r g a n i z a t i o n a l s t u d i e s . v o i . , p p . - , . c l i e b , r o b e r t c . , t r a n s d o r t a t i o p : t h e d o m e s t i c s y s t e m . n d e d i t i o n , r e s t o n p u b l i s h i n g , r e s t o n , v a . , . ) m a n d e l l , r o b e r t w. , f i n a n c i n g c a p i t a l r e q u i r e m e n t s o f t h e u. s . a i r l i n e i n d u s t r y i n t h e s . l e x i n g t o n b o o k s , h e a t h & c o . , l e x i n g t o n , m a s s . , . [ m e y e r , j . r . a n d c . v . o s t e r ( e d ) , a i r l i n e d e r e g u l a t i o n : t h e e a r l y e x o e r i en c e . a b u r n h o u s e , b o s t o n , . c m i l l e r , d . , a n d p . h . f r i e s e n , “ t h e l o n g i t u d i n a l a n a l y s i s o f o r g a n i z a t i o n s , " m a n a g e m e n t s c i e n c e . v o l . , n o . , p p . - , . [ m o r a s h , e d w a r d a . , a n d c h a r l e s e n i s , “ t h e e f f e c t s o f mo t o r c a r r i e r d e r e g u l a t i o n : a s t o c k m a r k e t p e r s p e c t i v e , " p r o c e d i n o s o f t h e r d a n n u a l m e e t i n g o f t h e t r a n s p o r t a t i o n r e s e a r c h f o r u m , p p . - , . £ o f f i c e o f t r a n s p o r t a t i o n p l a n n i n g , n a t i o n a i t r a n s p o r t a t i o n t r a n d s a n d c h o i c e s c t o t h e y e a r ) . u. s . d e p a r t m e n t o f t r a n s p o r t a t i o n . [ p o r t e r , m i c h a e l e . , c o m p e t i t i v e s t r a t e g y , f r e e p r e s s , n e w y o r k , . [ ) r u e f l i , t i m o t h y w. , a n d c h e s t e r l . w i l s o n , c o m p a r a t i v e r e l a t i v e r a n k m e t h o d o l o g y f o r i n d u s t r y a n d c o m p e t i t i v e a n a l y s i s , " g s b - u t w o r k i n g p a p e r / - - , . ( ) s a l a z a r , r o n a l d , a n d t i m o t h y w. r u e f l i , “ c o n c o r d a n c e m e a s u r e s f o r i n d u s t r y a n a l y s i s , i c w o r k i n g p a p e r , . [ ] s c h e r e r , f . m . , i n d u s t r i a l m a r k e t s t r u c t u r e a n d e c o n o m i c p e r f o r m a n c e . r a n d - m c n a l l y , c h i c a g o , . [ s p a d y , r i c h a r d h . , e c o n o m e t r i c e s t i m a t i o n o f c o s t f u n c t i o n s f o r t h e r e g u l a t e d t r a n s p o r t a t i o n i n d u s t r i e s . g a r l a n d p u b l i s h i n g , n e w y o r k , . ( ) s t e i n e r , g e o r g e , s t r a t e g i c p l a n n i n g . f r e e p r e s s , n e w y o r k , . [ ] t a n e j a , n a w a l k . , t h e u. s . a i r f r e i g h t i n d u s t r y . l e x i n g t o n b o o k s , h e a t h & c o . , l e x i n g t o n , m a s s . , . [ t a n e j a , n a w a l k . , u. s . i n t e r n a t i o n a l a v i a t i o n p o l i c y . l e x i n g t o n b o o k i s , h e a t h & c o . , l e x i n g t o n , m a s s . , . [ , t e m p l e , b a r k e r , & s l o a n e , i n c . , i n t r a n s o o r t a t i o n s t r a t e g i e s f o r t h e e i g h t i e s . n a t i o n a l c o u n c i l o f p h y s i c a l d i s t r i b u t i o n m a n a g e m e n t , o a k b r o o k , i l , . [ w y c o f f , d . d . , a n d d . h . m a i s t e r , t h e d o me s t i c a i r l i n e i n d u s t r y , l e x i n g t o n b o o k s , d . c . h e a t h & c o . , l e x i n g t o n , m a s s . , . p e r c e n t o f t o t a l p o s s i b l e u n c e r t a i n t y b y p e r f o r m a n c e d i m e n s i o n op r e v n e t i n e m p l r o e c n ( ) ( ) c d t r a n s p o r t a t i o n i n d u s t r y t o t a l u n c e r t a i n t y ................. . % . % . % . % r a i l r o a d s u b - g r o u p t o t a l u n c e r t a i n t y ................. . % . % . % . % a i r l i n e s u b - g r o u p t o t a l u n c e r t a i n t y ................. . % . % . % . % a s s e t s c ) . % . % . % n “ ) - t a b l e f i g u r e c a p t i o n s f g u r e t r a n s p o r t a t i o n i n d u s t r y v o l a t f g u r e r a i l r o a d v o l a t i l ty f g u r e r a i l r o a d p o s i t i o n f g u r e a r l n e v o l a t l ty f g u r e a i r l i n e p o s i t i o n f i g u r e t r u c k i n g v o l a t i l i t y f i g u r e t r u c k i n g p o s i t i o n f i g u r e p i p e l i n e p o s i t i o n f i g u r e c h i c a g o - m i l w a u k e e r a i l r o a d f i g u r e s o u t h e r n p a c i f i c r a i l r o a d f g u r e c o n s o l i d a t e d f r e i g h t w a y s f g u r e r o a d w a y e x p r e s s f g u r e u n i t e d p a r c e l s e r v i c e f g u r e c u a l d u n i t e d a i r l i n e s f g u r e n o r t h w e s t a i r l i n e s f g u r e d e l t a a i r l i n e s f g u r e a m e r i c a n a i r l i n e s f g u r e p a n a m e r i c a n a i r l i n e s volatility largest transportation firms a ~ i i i i i i i i i i i i i i i i j i i [ i t " b ̂ - n.i. period assets roe x empl a v e r a g e a b s o l u t e r an k s h if t volatility largest railroad firms period □ rev. - n.i. o assets a roe x empl - ■ - * ■ b • ■ ■ - - • rev position largest railroad firms njl year assets a roe x empl g volatility largest airline firms + n j . period o assets a roe x empl position largest airline companies i— i— r bo ̂ + n.i. year o assets a roe x empl ib b volatility largest trucking firms n.i. period assets roe l r b ̂ x empl a v e r a g e r a n k position largest trucking firms year □ rev. + n.i. o assets a roe x empl fi gu re a v e r a g e r a n k position largest pipeline firms n -j-!-,-j-,-j-j-,-,-j-,-,-,-j-,- -,-,-,-,-,-,-,-,-,- b bo b year □ rey. + n.i. o assets a roe x empl fi gu re r a n k chicago—milwaukee railroad rank performance year □ rev. + n.i. o assets a roe : x emp. fi gu re r a n k southern pacific railroad rank performance □ rev. + n.i. year o assets a roe x emp. consolidated freightways rank performance + n.i. year o assets a roe , x emp. r a n k roadway express rank performance year □ rev. + n j . o assets a roe x emp. r a n k united parcel service rank performance □ rev. + n.i. year .o assets a roe x emp. fi gu re r a n k united airlines (ual) rank performance year i a rev. + n.i. o assets a roe x emp. r a n k northwest airlines rank performance year □ rev. + n.i. o assets a r.oe x emp. fi gu re r a n k delta airlines rank performance □ rev. + n.i. year o assets a roe x emp. fi gu re r a n k american airlines rank performance year □ rev. + n.i. o assets a . roe x emp. fi gu re r a n k pan american airlines rank performance □ rev. + n.i. year o assets a roe] x emp. fi gu re 	ic cover page - ruefli 	ic -wp- - - doi: . /j.cub. . . magazine r news focus a new polar research effort is raising concerns that it may bolster fossil fuel extraction and increasingly threaten many local species. nigel williams reports. fears over arctic research plans an increasing number of researchers are concerned about a controversial plan by us colleagues to work alongside oil companies to hunt for fossil fuel reserves in the arctic. the us geological survey is lining up a project with bp and statoil to find oil and gas in the arctic ocean, under the auspices of a flagship scientific initiative intended to tackle global warming. tackling climate change and working out how it will affect the arctic and antarctic is a central theme of international polar year (ipy) — a high-profile project to start next spring that involves thousands of scientists from countries. the arctic is warming twice as fast as the rest of the planet and last september saw the lowest extent of sea ice cover for more than a century. scientists say that the temperature there could rise by a further – ºc by , and the arctic ocean could be ice free in summer by . documents on the ipy website show that bp and statoil, a norwegian company, are significant consortium members on a usgs proposal to assess “energy resources in the circumarctic area including oil, gas, coalbed methane and methane hydrates”. geologists estimate that a quarter of the world’s undiscovered oil and gas reserves lie under the arctic, and analysts have predicted a st- century goldrush to tap them as the arctic ocean’s ice cover retreats. launching the polar initiative last month, chris rapely, director of the british antarctic survey, said that scientists would work on projects “that will tackle the urgent environmental issues” because “rapid climate change is already impacting local peoples... and it is only a question of time before the wider consequences become apparent”. the inuit people have filed a lawsuit against the us government claiming that greenhouse gas pollution is damaging their livelihoods. experts have warned the only realistic way to prevent dangerous climate change is to curb carbon dioxide emissions from burning fossil fuels. unlike the antarctic continent, spread around the south pole, the arctic has no formal international treaty to regulate activities. and, while inclement conditions for dwindling: the polar ice cover is receding, opening up oceans to fossil fuel prospecting to the alarm of many researchers. (photo: peter menzel/science photo library.) current biology vol no r april was the day that brought public confirmation that a dead swan found in a scottish fishing village had succumbed to the h n avian influenza virus. the strain had emerged originally among chickens in china and the far east and had spread to and killed some of their handlers. after reaching various parts of mainland europe, the virus had now arrived in britain in the wake of growing concern over its capacity to ravage the country’s poultry industry. an even greater anxiety was that mutation or recombination might equip the agent for person-to-person transmission and thus spawn a lethal pandemic. so was media coverage on that critical day marked by sensational headlines and panicky hyperbole? scientists prone to blame journalists for offences of this sort would do well to reflect on what actually happened. in fact, a snapshot of the day’s newspaper columns revealed much level- headed writing. both ‘up-market’ and more popular titles sought to provide authoritative facts about the significance of the finding, and for the most part did so mediawatch: bernard dixon looks at the differing scottish and english newspaper responses to the first confirmed case of h n bird flu in the uk. a flap over bird flu very competently. some of the most impressive efforts to avoid over-reaction were in the scottish newspapers, nearest to the scene of the discovery, rather than in those published in london. eschewing the sort of headlines brandished by two especially colourful london-based papers, the scotsman’s front page read: “bird flu — answers to the key questions…leading experts assess the human threat and give practical advice.” this was followed by eight pages on every aspect of the story. in addition to local coverage of the situation in cellardyke, fife, where the swan was found, there were detailed accounts of the measures taken in the entire at-risk area and the reasoning behind them. a sober chronology of the detection of the h n virus in various countries since its initial appearance in china in was coupled with an explanation by virologist john oxford of the low risk to human health. there was cool coverage too in the aberdeen press and journal, under the page one banner “uk’s united front to fight bird flu scare”. again, the paper presented a comprehensive dossier of well- informed material, ranging from wildlife issues to the pros, cons and feasibility of vaccination for both chickens and humans. the only fevered note was a report of an attack by the scottish parliament’s environment minister most of the year kept prospectors at bay, there was little to regulate. but as global warming thaws the ocean’s layers, oil giants, shipping companies and even the odd enterprising tourist operator are casting their eyes towards the high north. the biggest boom could be in oil and gas. the us geological survey surprised some experts when it declared that a quarter of the world’s undiscovered reserves lay under the arctic ocean. as the ice retreats, oil companies are scrambling to open a new frontier. attempts to open up the arctic national wildlife refuge in alaska to drilling remain deadlocked in the us congress, but several companies have dipped more than a toe in the chilly arctic ocean further north. bp amoco is developing an alaskan offshore oil deposit called northstar and statoil is working on a gas field miles across the barents sea from its most northerly outpost, hammerfest. called snow white, the project is expected to start pumping liquefied natural gas to the us and europe next year. environmental campaigners are viewing the creeping development of the arctic with mounting concern. norway announced last month that it will limit drilling in some areas to protect at  sea: a signature arctic species, the walrus, is under growing threat from summer fragmentation of sea ice. (photo: daniel cox/photolibrary.) fragile ecosystems. the -mile exclusion zone in the barents sea has large supplies of fish. but the embargo expires in and drilling elsewhere is being stepped up, with the granting of gas and oil licences to companies. stephanie tumore, a climate campaigner with greenpeace, said: “haven’t we learnt anything? why are we going looking for more fossil fuels when what’s happening in the polar regions just proves that it is devastating and we cannot continue to do that.” the present energy crisis results from a sharp rise in consumption that has outrun a tightening supply, writes peter canby in a recent issue of the new york review of books. “most of the oil in the united states is used for fueling the cars and trucks that have been almost entirely responsible for the growth in demand over the last few decades.” now, , square miles of arctic tundra on alaska’s north slope is home to one of the world’s largest industrial complexes, with oil production plants, , exploration and production wells, , miles of pipes and miles of roads. the spread of this sort of development around the arctic raises many new fears. dark energy, qcd axion, bicep , and trans-planckian decay constant dark energy, qcd axion, bicep , and trans-planckian decay constant � jihn e. kim department of physics, kyung hee university, seoul - , korea abstract discrete symmetries allowed in string compactification are the mother of all global symmetries which are broken at some level. we discuss the resulting pseudo-goldstone bosons, in particular the qcd axion and a temporary cosmological constant, and inflatons. we also comment on some implications of the recent bicep data. keywords: discrete symmetry, qcd axion, dark energy, inflation . discrete symmetries the cosmic energy pie is composed of % dark energy (de), % cold dark matter (cdm), and % atoms [ ]. among these, some of de and cdm can be bosonic coherent motions (bcms) [ ]. the ongoing search of the qcd axion is based on the bcm. being a pseudo-goldstone boson, the qcd axion can be a com- posite one [ ], but after the discovery of the fundamen- tal brout-englert-higgs (beh) boson, the possibility of the qcd axion being fundamental gained much more weight. the ongoing axion search experiment is based on the resonance enhancement of the oscillating e-field following the axion vacuum oscillation as depicted in fig. . it may be possible to detect the cdm axion even its contribution to cdm is only % [ ]. the beh boson is fundamental. the qcd axion may be fundamental. the inflaton may be fundamen- tal. these bosons with canonical dimension can af- fect more importantly to low energy physics compared to those of spin- fermions of the canonical dimension . this leads to a beh portal to the high energy scale to the axion scale or even to the standard model (sm) singlets at the grand unification (gut) scale. can these �this work is supported by the nrf grant funded by the korean government (mest) (no. - ). email address: jihnekim@gmail.com (jihn e. kim) singlets explain both de and cdm in the universe? be- cause the axion decay constant fa can be in the interme- diate scale, axions can live up to now (ma < ev) and constitute dm of the universe. in this year of a gut scale vev, can these also explain the inflation finish? for pseudo-goldstone bosons like axion, we intro- duce global symmetries. but global symmetries are known to be broken by the quantum gravity effects, es- pecially via the planck scale wormholes. to resolve this dilemma, we can think of two possibilities of dis- crete symmetries below mp [ ]: (i) the discrete sym- metry arises as a part of a gauge symmetry, and (ii) the string selection rules directly give the discrete sym- • • • • • • • • b 〈a〉� ea figure : the resonant detection idea of the qcd axion. the e-field follows the axion vacuum oscillation. available online at www.sciencedirect.com nuclear and particle physics proceedings – ( ) – - /© elsevier b.v. all rights reserved. www.elsevier.com/locate/nppp http://dx.doi.org/ . /j.nuclphysbps. . . http://www.elsevier.com/locate/nppp http://dx.doi.org/ . /j.nuclphysbps. . . http://dx.doi.org/ . /j.nuclphysbps. . . http://www.sciencedirect.com global symmetry d is c r e te sy m m e tr y gl d figure : terms respecting discrete and global symmetries. metry. so, we will consider discrete gauge symme- tries allowed in string compactification. even though the goldstone boson directions in spontaneously bro- ken gauge symmetries are flat, the goldstone boson di- rections of spontaneously broken global symmetries are not flat, i.e. global symmetries are always approximate. the question is what is the degree of the approximate- ness. in fig. , we present a cartoon separating effective terms according to string-allowed discrete symmetries. the terms in the vertical column represent exact sym- mmetries such as gauge symmetries and string allowed discrete symmetries. if we consider a few terms in the lavender part, we can consider a global symmetry. with the global symmetry, we can consider the global sym- metric terms which are in the lavender and green parts of fig. . the global symmetry is broken by the terms in the red part. the most studied global symmetry is the peccei- quinn (pq) symmetry u( )pq [ ]. for u( )pq, the dominant breaking term is the qcd anomaly term (θ/ π )gμνg̃μν where gμν is the gluon field strength. since this θ gives a neutron edm (nedm) of order − θecm, the experimental upper bound on nedm re- stricts |θ| < − . “why is θ so small?” is the strong cp problem. there have been a few solutions, but the remaining plausible solution is the very light axion so- lution [ ]. in field theory, it is usually talked about in terms of the ksvz axion [ ] and the dfsz axion [ ], and there are several possibilities even for these one heavy quark or one pair of beh doublets [ ]. for axion detection through the idea of fig. , the axion- photon-photon coupling caγγ is the key parameter. in our search of an ultra-violet completed theory, the cus- tomary numbers of [ ] are ad hoc. from string theory, so far there is only one calculation on caγγ [ ]. to cal- culate caγγ, the model must lead to acceptable sm phe- nomenology, otherwise the calculation does not lead to a useful global fit to all experimental data. . dark energy and qcd axion it is interesting to note that the qcd axion must arise if one tries to introduce the de scale via the idea of fig. [ , ]. the de and qcd axions are the bcm ex- amples. dark energy is classified as cctmp and qcd axion is classified as bcm in [ ]. note that the global symmetry violating terms belong to the red part in fig. . for the qcd axion, the domi- nant breaking is by the qcd anomaly term, which leads to the qcd axion mass in the range of milli- to nano- ev for fa � − gev. in the beh portal scenario, the de pseudoscalar must couple to the color anomaly since it couples to the beh doublet and the beh scalar couples to the quarks. on the other hand, a cctmp psudoscalar mass is in the range − ∼ − ev [ ]. therefore, the qcd anomaly term is too large to ac- count for the de scale of − gev , and we must find out a qcd-anomaly free global symmetry. it is possible by introducing two global u( ) symmetries [ , ]. in addition, the breaking scale of u( )de is trans- planckian [ ]. including the anharmonic term care- fully with the new data on light quark masses, a recent calculation of the cosmic axion density gives the axion window [ ], gev < fa < gev. ( ) it is known that string axions from bmn have gut scale decay constants [ ]; hence the qcd axion from string theory is better to arise from matter fields [ ]. for the qcdaxion, the height of the potential is ≈ Λ qcd. for the de pseudo-goldstone boson, the height of the po- tential is ≈ m gut, according to the beh portal idea, im (Φ) re (Φ) v (Φ) fde − gev � o(m g) • figure : the de potential in the red angle direction in the valley of radial field of height ≈ m gut. j.e. kim / nuclear and particle physics proceedings – ( ) – as shown in fig. . with u( )pq and u( )de, one can construct a de model from string compactification [ ]. using the susy language, the discrete and global sym- metries below mp are the consequence of the full super- potential w. so, the exact symmetries related to string compactification are respected by the full w, i.e. the ver- tical column of fig. . considering only the d = superpotential w , we can consider an approximate pq symmetry. for the mssm interactions supplied by r- parity, one needs to know all the sm singlet spectrum. we need z for a wimp candidate. introducing two global symmetries, we can remove the u( )de-g-g where g is qcd and the u( )de charge is a linear combination of two global symmetry charges. the decay constant corresponding to u( )de is fde. in- troduction of two global symmetries is inevitable to in- terpret the de scale and hence in this scenario the ap- pearance of u( )pq is a natural consequence. the height of de potential is so small, − gev , that the needed discrete symmetry breaking term of fig. must be small, implying the discrete symmetry is of high order. now, we have a scheme to explain both % of de and % of cdm via approximate global symmetries. with susy, axino may contribute to cdm also [ ]. a typical example for the discrete symmetry is z r as shown in [ ]. the z r charges descend from a gauge u( ) charges of the string compactification [ ]. then, the height of the potential is highly suppressed and we can obtain − gev , without the gravity spoil of the global symmetry. in this scheme with beh por- tal, we introduced three scales for vacuum expectation values (vevs), tev scale for hu hd , the gut scale mgut for singlet vevs, and the intermediate scale for the qcd axion. the other fundamental scale is mp. the trans-planckian decay constant fde can be a derived scale [ ]. spontaneous breaking of u( )de is via a mexican hat potential with the height of m gut. a byproduct of this mexican hat potential is the hilltop inflation with the height of o(m gut), as shown in fig. . it is a small field inflation, consistent with the planck data. . gravity waves from u( )de potential however, with the surprising report from the bicep group on a large tensor-to-scalar ratio r [ ], we must reconsider the above hilltop inflation whether it leads to appropriate numbers on ns,r and the e-fold number e, or not. with two u( )’s, the large trans-planckian fde is not spoiled by the intermediate pq scale fa because the pq scale just adds to the fde decay constant only by a tiny amount, viz. fde → √ f de + o( ) × f a ≈ fde for | fa/ fde � − |. inflaton potentials with almost flat one near the ori- gin, such as the coleman-weinberg type new inflation, were the early attempts for inflation. but any models can lead to inflation if the potential is flat enough as in the chaotic inflation with small parameters [ ]. a single field chaotic inflation survived until now is the m φ scenario chaotic inflation with m = o( gev). to shrink the field energy much lower than m p, a nat- ural inflation (mimicking the axion-type − cos poten- tial) has been introduced [ ]. if a large r is observed, lyth noted that the field value 〈φ〉 must be larger than mp, which is known as the lyth bound [ ]. to obtain this trans-planckian field value, the kim-nilles- peloso (knp) -flation has been introduced with two axions [ ]. it is known recently that the natural infla- tion is more than σ away from the central value of bi- cep , (r,ns) = ( . , . ). in general, the hilltop infla- tion gives almost zero r. this is because ns � − r+ η which gives ns = . for (r,η) = ( . , ). to raise ns from . to . , we need a positive η, but the hilltop point gives a negative η. therefore, for the u( )de hilltop inflation to give a suitable ns with a large r, one must introduce another field which is called chaoton because it provides the be- havior of m φ term at the bicep point [ ]. with this hilltop potential, the height is of order m gut and the decay constant is required to be > mp. cer- tainly, the potential energy is smaller than order m p for φ = [ , fde]. since this hilltop potential is obtained from the mother discrete symmetry, such as z r, the flat valley up to the trans-planckian fde is possible, for which the necessary condition is given in terms of quan- tum numbers of z r [ ]. . the knp model and u( )de hilltop inflation a large vev of a scalar field is possible if a very small coupling constant λ is assumed in v = λ(|φ| − f ) with a small mass parameter m = λ f . with a gut scale m, f can be trans-planckian of order mp for λ < − . but this potential is a single field hilltop type and it is not favored by the above argument with the bicep data [ ]. this has led to the recent surge of studies on concave potentials near the origin of the single field. the concave potentials give positive η’s. to cut off the potential exceeding the gut scale m gut, the natural inflation with a gut scale confin- ing force has been introduced [ ]. with two confin- ing forces, it was possible to raise a decay constant of j.e. kim / nuclear and particle physics proceedings – ( ) – the gut scale axions above mp, which is known as the kim-nilles-peloso (knp) -flation model [ ]. in terms of two axions a and a and two gut scale (Λ and Λ ) confining forces, the minus-cosine potentials can be written as v = Λ ( − cos [ α a f +β a f ) ]) + Λ ( − cos [ γ a f +δ a f ) ]) , ( ) where α,β,γ, and δ are determined by two u( ) quan- tum numbers. if there is only one confining force, we can set Λ = in eq. ( ), which is depicted in fig. (a). the flat red valley cannot support the inflation energy. the situation with two confining forces is shown in fig. (b). the inflation path is shown as the arrowed blue curve on top of the red valley on the yellow roof. in this case, we consider a × mass matrix, m = ⎛⎜⎜⎜⎜⎜⎜⎜⎜⎜⎝ f ( α Λ +γ Λ ) , f f (αβΛ +γδΛ ) f f (αβΛ +γδΛ ), f (β Λ +δ Λ ) ⎞⎟⎟⎟⎟⎟⎟⎟⎟⎟⎠ • • −π −π ah/fah ai/fai π π π π (a) • −π −π ah/fah ai/fai π π (b) figure : two-flation. (a) the flat valley with one confining force, and (b) the knp model with two confining forces. whose eigenvalues are [ ], m h = (a + b) and m i = (a − b) . ( ) with a = ⎛⎜⎜⎜⎜⎝α Λ +γ Λ f + β Λ +δ Λ f ⎞⎟⎟⎟⎟⎠ , b = √ a − (αδ−βγ) Λ Λ f f . ( ) from eq. ( ), we note that a large fi is possible for αδ= βγ+Δ with Δ ≈ . then, the inflaton mass is m i � Δ Λ Λ f (α Λ +γ Λ ) + f (β Λ +δ Λ ) . for Λ =Λ and f = f ≡ f , it becomes m i � Λ (α +β +γ +δ ) f /Δ . ( ) the pq quantum numbers α,β,γ, and δ are not random priors, but given definitely in a specific model. the per- spectives of - and n-flations are given in [ ]. even though a large trans-planckian decay constant is in principle possible with large pq quantum numbers in the knp model, string compactification may not al- low that possibility. the n-flation with a large n has a more severe problem in string compactification [ ]. this invites to look for another possibility of generating trans-planckian decay constants. since the knp model already introduced two axions, we look for a possibility of introducing another field (called chaoton before) in the hilltop potential. in effect, the chaoton is designed to provide a positive η. the hilltop potential of fig. is a mexican hat poten- tial of u( )de, i.e. obtained from some discrete symme- try, allowed in string compactification [ ]. the discrete symmetry may provide a small de scale. the trans- planckian decay constant, satisfying the lyth bound, is obtained by a small coupling λ in the hilltop potential v . the requirement for the vacuum energy being much smaller than m p is achieved by restricting the inflaton path in the hilltop region, 〈φ〉 � fde, as shown in fig. . in fig. , the inflation path affected by chaoton is depicted as the green path. we can compare this hilltop inflation assisted by chaoton with the m φ chaotic inflation. the hilltop in- flation is basically a consequence of discrete symme- tries [ , , ] , allowed in string compactification. if some conditions are satisfied between the discrete quantum numbers of the gut scale fields and trans- planckian scale fields, the hilltop potential of fig. can j.e. kim / nuclear and particle physics proceedings – ( ) – φ mp o(m p) v • 〈φ〉 fde o(m gut) figure : the trans-planckian decay costant in the hilltop inflation. result [ ]. on the other hand, the m φ chaotic infla- tion does not have such symmetry argument, and lacks a rationale forbidding higher order φn terms. this ar- gument was used to forbid many interesting theories by considering the observed slow-roll parameter η from in- flation assumption [ ]. but the situation is much worse here than lyth’s case. for example, for an n = term for the trans-planckian field Φ and the gut scale field φ, one must fine-tune the coupling out of for the trans-planckian singlet vev of order 〈Φ〉 ≈ mp [ ]. . pq symmetry breaking below hi cosmology of axion models was started in – [ ] with the micro-ev axions [ , ]. the needed axion scale given in eq. ( ), far below the gut scale, is understood in models with the anomalous u( ) in string compactification [ ]. in addition to the scale problem, there exists the cosmic-string and domain wall (dw) problem [ , ]. here, i want to stress that the ax- ion dw problem has to be resolved without the dilution effect by inflation. the bicep finding of “high scale inflation at the gut scale” implies the reheating temperature after in- flation � gev. then, studies on the isocurvature constraint with the bicep data pin down the axion mass in the upper allowed region [ ]. but this axion mass is based on the numerical study of ref. [ ] which has not included the effects of axion string-dw annihi- lation by the vilenkin-everett mechanism [ ]. in fig. , we present the case for ndw = . topological defects are small balls ((a) and (b)), whose walls separarte θ= and θ= π vacua, and a horizon scale string-wall system. collisions of small balls on the horizon scale walls do not punch a hole, and the horizon size string-dw system is not erased ((c) and (d)). therefore, for ndw ≥ axion models, there exists the cosmic energy crisis problem of (a) (b) (c) (d) figure : small dw balls ((a) and (b), with punches dshowing the inside blue-vacuum) and the horizon scale string-wall system ((c) and (d)) for ndw = . yellow walls are θ = walls, and yellow-green walls are θ= π walls. yellow-green walls of type (b) are also present. the string-dw system. in fig. , we present the case with ndw = . topological defects are small disks and a horizon scale string-dw system ((a)). collisions of small balls on the horizon scale walls punch holes ((b)), and the holes expand with light velocity. in this way, the string-wall system is erased ((c)) and the cosmic energy crisis problem is not present in ndw = axion models [ ], for example with one heavy quark in the ksvz model. if the horizon-scale string-dw system is absent, there is no severe axion dw problem. so, with the bicep report, it became of utmost im- portance to obtain ndw = axion models. the first try along this line was the so-called lazarides-shafi mech- anism, using the center (discrete group) of gut gauge groups [ ]. a more useful discrete group is a discrete subgroup of continuous u( )’s, i.e. the discrete points of the longitudinal goldstone boson directions of gauged u( )’s [ ]. in string theory, the anomalous gauged u( ) is useful for this purpose [ ]. this solution has (a) (b) (c) figure : the horizon scale string-wall system with ndw = . any point is connected to another point, not passing through the wall. . j.e. kim / nuclear and particle physics proceedings – ( ) – |g a γ |[g ev − ] maxion[ev] − − − − − − − − − − tokyo cast phase i cast ii he he tokyo helioscope lazarus et al. hb stars dama solax, cosme h d m − − iaxo plan − − − − bicep a xi o n m o d el s< [k s v z ( e( q )= ) ] k s v z ( e( q )= ) d f s z ( d ,e ) u n if . h k k f lip -s u ( ) figure : the gaγ(= . × − caγγ) vs. ma plot [ ]. been recently obtained in z −i orbifold compactifica- tion [ ]. the qcd-axion string-dw problem may not appear at all if the hidden-sector confining gauge theory con- spire to erase the hidden-sector string-dw system [ ]. here, we introduce just one axion, namely through the anomalous u( ) gauge group, surviving down to the ax- ion window as a global u( )pq. here, we introduce two kinds of heavy quarks, one the su(nh) heavy quark qh and the other su( )qcd heavy quark q. then, the type of fig. is present with two kinds of walls: one of Λh wall and the other of Λqcd wall. but, at t ≈ Λh only Λh wall is attached. at somewaht lower tempera- ture ter (<Λh) the string-dw system is erased à la fig. . the height of the Λh wall is proportional to mqhΛ h with mqh = f 〈x〉. the vev 〈x〉 is temperature depen- dent, and it is possible that 〈x〉 = below some critical temperature tc (< ter). then, the Λh wall is erased be- low tc, and at the qcd phase transition only the qcd wall is present. but, all horizon scale strings have been erased already and there is no energy crisis problem of the qcd-axion string-dw system. therefore, pinpoint- ing the axion mass using the numerical study of ref. [ ] is not water-proof. the ndw = models are very attractive and it has been argued that the model-independent axion in string models, surviving down as a u( )pq symmetry below the anomalous u( ) gauge boson mass scale, is good for this. at the intermediate mass scale qpq = should obain a vev to have ndw = . in a z −i orbifold compactification present in ref. [ ], the axion-photon- photon coupling has been calculated [ ], caγγ = − . � − . , ( ) which is shown as the green line in the axion coupling vs. axion mass plot, fig. . references [ ] p. a. r. ade et al.(planck collaboration), arxiv: . [astro-ph.co]. [ ] j. e. kim et al., arxiv: . . [ ] j. e. kim, phys. rev. d ( ) . [ ] capp site, http://capp.ibs.re.kr/html/capp en. [ ] j. e. kim, phys. lett. b ( ) . [ ] r. d. peccei and h. r. quinn, phys. rev. lett. ( ) . [ ] j. e. kim and g. carosi, rev. mod. phys. ( ) . [ ] j. e. kim, phys. rev. lett. ( ) ; m. a. shifman et al., nucl. phys. b ( ) . [ ] a. p. zhitnitsky, yad. fiz. ( ) : [sov. j. nucl. phys. ( ) : ]; m. dine, w. fischler and m. srednicki, phys. lett. b ( ) . [ ] j. e. kim, phys. rev. d ( ) . [ ] j. e. kim, phys. lett. b ( ) [arxiv: . .v ]. [ ] j. e. kim and h. p. nilles, phys. lett. b ( ) . [ ] j. e. kim, j. korean phys. soc. ( ) . [ ] s. m. carroll, phys. rev. lett. ( ) . [ ] k. j. bae et al., jcap ( ) . [ ] k. choi and j. e. kim, phys. lett. b ( ) ; p. svrcek and e. witten, jhep ( ) . [ ] j. e. kim, phys. rev. lett. ( ) . [ ] h. baer et al., arxiv: . . [ ] j.-h. huh et al., phys. rev. d ( ) . [ ] j. e. kim et al., jcap ( ) . [ ] p. a. r. ade et al.(bicep collaboration), phys. rev. lett. ( ) . [ ] a. d. linde, phys. lett. b ( ) . [ ] k. freese et al., phys. rev. lett. ( ) . [ ] d. h. lyth, phys. rev. lett. ( ) . [ ] j. e. kim, phys. lett. b ( ) . [ ] k. y. choi et al., arxiv: . [hep-th]. [ ] d. h. lyth, arxiv: . [hep-ph]. [ ] j. preskill et al., phys. lett. b ( ) ; l. f. abbott and p. sikivie, phys. lett. b ( ) ; m. dine and w. fischler, phys. lett. b ( ) . [ ] j. e. kim, phys. lett. b ( ) . [ ] j. e. kim, phys. lett. b ( ) . [ ] a. vilenkin and a. e. everett, phys. rev. lett. ( ) . [ ] p. sikivie, phys. rev. lett. ( ) . [ ] d. j. e. marsh et al., phys. rev. lett. ( ) ; l. vissineli and p. gondolo, phys. rev. lett. ( ) . [ ] t. hiramatsu et al., phys. rev. d ( ) . [ ] g. lazarides and q. shafi, phys. lett. b ( ) . [ ] k. choi and j. e. kim, phys. rev. lett. ( ) . [ ] s. m. barr et al., nucl. phys. b ( ) . [ ] j. e. kim, phys. lett. b ( ) . [ ] s. m. barr and j. e. kim, arxiv: . [hep-ph]. [ ] h. baer et al., arxiv: arxiv: . [hep-ph]. j.e. kim / nuclear and particle physics proceedings – ( ) – bioenergy and environment vol.:( ) waste and biomass valorization ( ) : https://doi.org/ . /s - - - e d i to r i a l bioenergy and environment wenchao ma  · guanyi chen , published online: november © springer nature b.v. energy crisis and climate change is a worldwide concern. development of renewable energy as an alternative to fos- sil fuel attract more attention in recent years. according to report published by ren , renewable energy contributed . % to human’s global energy consumption in , and . % was from traditional biomass. bioenergy has its unique advantages, such as c-neutral property, the only renewable energy able to convert into the forms of liquid, gas and solid products. the utilization of biomass can fulfill the strong need of both energy and environment. the complex structure of biomass, as of cellulose, semi- cellulose and lignin has posed a great challenge to research- ers about how to convert it with high efficiency and high quality products. recent developments on accurate analysis device (marco-tga, py-gc/ms, synchrotron vuv pho- toionization mass spectrometry), new catalysts, new reac- tors and assistant technologies (microwave, ultrasonic wave, plasma etc.) may bring the opportunity to these concerns. on the other hand, the utilization of biomass may lead to the environmental pollutions (pah, dioxin, etc.). future work needs to identify an integration of resource utilization and benefit to the environment as well. therefore, this special issue will address recent research advances in bioenergy and environment interaction stud- ies on waste utilization and conversion, biofuel production, pollution control and remediation. however, we have done many pieces of research, but this was not the end of the story. there is various other information that researchers need to seek more to clean bioenergy and less environmen- tal/ecosystem impacted. publisher’s note springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. * guanyi chen chen@tju.edu.cn wenchao ma mawc @tju.edu.cn school of environmental science and engineering, tianjin university, tianjin  , china school of science, tibet university, lhasa  , china http://crossmark.crossref.org/dialog/?doi= . /s - - - &domain=pdf 	bioenergy and environment a practical biogas based energy neutral home system for rural communities of bangladesh a practical biogas based energy neutral home system for rural communities of bangladesh c. k. das, m. a. ehsan, m. a. kader, m. j. alam, and gm shafiullah citation: journal of renewable and sustainable energy , ( ); doi: . / . view online: http://dx.doi.org/ . / . view table of contents: http://scitation.aip.org/content/aip/journal/jrse/ / ?ver=pdfcov published by the aip publishing articles you may be interested in performance evaluation, energy conservation potential, and parametric study of borehole heat exchanger for space cooling in building j. renewable sustainable energy , ( ); . / . thermal performance prediction and energy conservation potential of earth air tunnel heat exchanger for thermal comfort in building j. renewable sustainable energy , ( ); . / . optimization of photovoltaics panels area at serbian zero-net energy building j. renewable sustainable energy , ( ); . / . hellenic renewable energy policies and energy performance of residential buildings using solar collectors for domestic hot water production in greece j. renewable sustainable energy , ( ); . / . energy use and environmental impacts: a general review j. renewable sustainable energy , ( ); . / . reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : http://scitation.aip.org/content/aip/journal/jrse?ver=pdfcov http://oasc . realmedia.com/realmedia/ads/click_lx.ads/www.aip.org/pt/adcenter/pdfcover_test/l- / /x /aip-pt/jrse_articledl_ /aip- _eic_apl_photonics_ x r .jpg/ c a a c b f?x http://scitation.aip.org/search?value =c.+k.+das&option =author http://scitation.aip.org/search?value =m.+a.+ehsan&option =author http://scitation.aip.org/search?value =m.+a.+kader&option =author http://scitation.aip.org/search?value =m.+j.+alam&option =author http://scitation.aip.org/search?value =gm+shafiullah&option =author http://scitation.aip.org/content/aip/journal/jrse?ver=pdfcov http://dx.doi.org/ . / . http://scitation.aip.org/content/aip/journal/jrse/ / ?ver=pdfcov http://scitation.aip.org/content/aip?ver=pdfcov http://scitation.aip.org/content/aip/journal/jrse/ / / . / . ?ver=pdfcov http://scitation.aip.org/content/aip/journal/jrse/ / / . / . ?ver=pdfcov http://scitation.aip.org/content/aip/journal/jrse/ / / . / . ?ver=pdfcov http://scitation.aip.org/content/aip/journal/jrse/ / / . / . ?ver=pdfcov http://scitation.aip.org/content/aip/journal/jrse/ / / . / . ?ver=pdfcov http://scitation.aip.org/content/aip/journal/jrse/ / / . / . ?ver=pdfcov http://scitation.aip.org/content/aip/journal/jrse/ / / . / . ?ver=pdfcov http://scitation.aip.org/content/aip/journal/jrse/ / / . / . ?ver=pdfcov a practical biogas based energy neutral home system for rural communities of bangladesh c. k. das, ,a) m. a. ehsan, ,b) m. a. kader, m. j. alam, and gm shafiullah department of electrical and electronic engineering, chittagong university of engineering and technology, chittagong , bangladesh department of electrical and electronic engineering, international islamic university chittagong, chittagong , bangladesh department of electrical and electronic engineering, bangladesh university of engineering and technology, dhaka , bangladesh department of electrical engineering, energy and physics, school of engineering and information technology, murdoch university, murdoch, western australia , australia (received june ; accepted february ; published online march ; publisher error corrected march ) growing demand of energy consumption, subsequent increase in energy generation costs, and increased greenhouse gas (ghg) emissions, as well as global warming from the conventional energy sources, encourages interest worldwide to bring a higher percentage of renewable energy sources such as biogas into the energy mix to build a climate friendly environment for the future. moreover, due to high investment and maintenance costs, governments are not providing enough support for grid extension and delivering electricity to remote locations or rural areas, in particular, in under-developing countries like bangladesh. therefore, this paper presents an energy neutral home system (enhs) that can meet all its energy requirements from low-cost, locally available, nonpolluting biogas generated from animal waste, in particular, chicken and cow manure. the proposed enhs has been developed for rural community, typically an area of families, and will not only provide cooking gas and sustainable and affordable power supply to the community with low emissions, but will also facilitate high quality fertilizer for agricultural purposes. in-depth analysis clearly demonstrates that the proposed enhs not only offers electricity and cooking gas to the community with the lowest costs, but also reduces the energy crisis and ghg emissions and can play an active role in developing socio-economic infrastructure of rural communities in bangladesh in many ways. vc aip publishing llc. [http://dx.doi.org/ . / . ] i. introduction energy demands are increasing at unprecedented rates worldwide in both developed and developing countries, already reaching formidable levels. the lack of the ready energy avail- ability to meet these demands causes inevitable disparity between people and nations globally. around the world, . � people or roughly a quarter of the global population have no access to reliable electricity. most of the rural areas that are far from the mainland or city and islands lack access to modern facilities as well as energy services, which have to be considered as a significant global development challenge today. reliable and continuous electricity supply is required for economic development of the communities as well as delivery of key public services, including health, education, and infrastructure. moreover, energy is currently being generated mainly from fossil fuelled power generation that contributes greenhouse gas (ghg) a) author to whom correspondence should be addressed. electronic mail: choton @gmail.com. mobile: þ - b) electronic mail: amimul @gmail.com - / / ( )/ / /$ . vc aip publishing llc , - journal of renewable and sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : http://dx.doi.org/ . / . http://dx.doi.org/ . / . http://dx.doi.org/ . / . mailto:choton @gmail.com mailto:amimul @gmail.com http://crossmark.crossref.org/dialog/?doi= . / . &domain=pdf&date_stamp= - - emissions into the atmosphere causing changes in global climate condition. these impacts include land, water, and air pollution, widespread habitat annihilation, along with swelling evi- dence of links between fossil fuel use and climate change due to global warming. – augmented concern about global warming, acid rain, and air pollution has rejuvenated attention in the application of renewable energy (re) resources, which has started to be used as a panacea for solving climate change and also reducing the energy crisis worldwide. among all renewable sources, bioenergy is estimated to be the fourth largest resource in the world. biogas is one of the major categories of an exploitable form with huge biopotential, and it can be produced from almost all kinds of waste sources. there have been colossal researches on biogas production and plant efficiency, so the present key research factor is optimization of biogas systems. in one research paper, operational aspects of two large industrial anaerobic digestion (ad) amenities and their performances for two years of operation are discussed, which indicates that proper monitoring and management can increase biogas production by %, but the system is implemented only for urban areas. the technical and economic performance of an anaerobic digestion family size biogas plant ( m volume) installed in turkey is investigated in a study which corroborates that the lowest pay back time (pbt) is . years considering the retailing price of natural gas and solid fertilizer follow the turkish market rates of e . /m and e /t, respectively. it is concluded from the research that the pbt will decreases even more if energy maize (em) utilization rates increase and a lower pbt can also be obtained with a greater income from biogas and fertilizer. in an inclusive research, the ad of cattle, swine, and poultry wastes with carefully chosen ratios is carried out to evaluate their biogas yields. the research affirms that a farm owner can get optimum biogas by blending cattle dung, swine, and poultry wastes in the precise ratio of : : or : : and that temperature variations within the mesophilic range do not affect biogas formation. a study illustrates that the popularity of biogas surges to a peak by upgrading to numerous available efficient forms of fuel. taking into account energy efficiency and global warming potential, the study of conversion of biogas to compressed biogas (cbg), liquefied biogas (lbg), fischer-tropsch diesel (ftd), methanol, and dimethyl ether (dme) revealed that dme gave the best performance of the fuel conversion scenarios considered. in another research paper, the effects of storage time and storage temperature on subse- quent biogas production from cow manure are investigated and its outcomes are that storage of digestate at �c has no significant effect on consequent biogas production, but at �c, it decreases from . m /t to m /t of fresh digestate and a decline of volatile solid concentra- tion in the stored digestate to . g/kg/week is also observed. another remarkable method named flexible biogas production is employed, which offers the opportunity to minimize the necessary gas storage capacity and thus saves storage investments predominantly. the authors conclude that biogas can be produced with high flexibility using diurnal flexible feeding and precise combinations of substrates with different degradation kinetics. evaluation of distinctive economic and ecological metrics for multiple objective considera- tions is undertaken in a life cycle-based accounting model of a domestic biogas system. a typi- cal household biogas system in gongcheng, china, is ideal for a case study. the outcomes are $us net benefit for each family unit compared to no biogas-linked peasants, savings of . m firewood for each household biogas unit, and reductions of kg of co and . kg of so emissions, which equate to . � j and . � j of environmental emis- sion energy saved. the resulting co reduction would be worth $us . � of potential carbon trading value for the whole of gongcheng. indirect social benefits include diminution of germs dispersal, enhancement of labor intensity, etc. in a noteworthy article, the authors show that biogas production can affect the emissions of ghgs in a number of ways, but considering other factors relating to farm-scale ad like fer- tilizer replacement, firewood substitutes, lighting kerosene, increased agricultural production, green area augmentation, etc., these ghgs are well-balanced. - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : household air pollution is ascribed as the cause of global deaths of . � people and % of those are owing to cardiovascular complications while % are due to adverse effects on respiratory health. most conspicuous sufferers are women and children because of the defi- ciency of ventilation, fuel type, kitchen volume, stove type, eave spaces in kitchen walls, etc. high levels of cardiovascular disease, stroke risk, high blood pressure, etc., are found among adult females of rural areas where solid wood is used for cooking. an allied research team conducted an epidemiological study to assess the real-life impact of biogas interventions on the risk of hypertension in rural nepal considering two groups of cooks—(i) aged greater than years and (ii) aged between – years. the study indicated that systolic blood pressure (sbp) increases with increasing age, diastolic blood pressure (dbp) decreases after years, and lower sbp and dbp are more marked in biogas users than wood users. statistics show that, in india, % of total household energy consumption is for cooking, and most of this uses biomass resources like cow dung, fuel wood, crop residues, etc. cooking takes up about hr/day in rural areas for a typical family due to the low calorific value of solid fuels, which causes slow burning and low efficiency of mud stoves. the study correspondingly relates that one of the major reasons of school dropouts among rural children is being busy with wood collection. in another study, it was observed that ad-induced increases in phytotoxic substances such as ammonia, volatile organic compounds, or nutrient discrepancies counteracted by agronomic measures, which in turn recuperates plant growth and overwhelms disease likelihoods. an excellent planning concept has been pioneered for implementation of renewable energy in local communities in developing countries, exemplified by a vietnamese case. comprehensive researches and pilot projects have been performed in many countries like germany, denmark, sweden, china, serbia, kenya, croatia, and so on, and demonstrate benefits that cut across issues of dimension, scale, and resilience. – germany has made auspicious progress through amend- ments in legislation requiring % renewable power consumption by and the direct retailing of biogas power in the german electricity market. bangladesh is a land of opportunities, but the energy crisis is one of the largest threats to its development. % of the total � population of bangladesh inhabit rural areas; how- ever, only . % of total inhabitants have access to electricity, and almost % of rural areas are still without electrification. the present peak power demand of bangladesh is mw, and the highest generation is mw; , demand is predicted to increase to mw by . . % of the existing power plants are natural gas based while prevailing natural gas resources are decreasing continuously and are assumed to dry up by . hence, the country is urgently exploring short, medium, and long term alternatives, including planning to set up nuclear power plants to meet this increasing demand, but there are many technical complica- tions and debates in this issue. limited diesel generator facilities exist but are too expensive and burning fossil fuels is not a sustainable long term option. owing to climate change and global warming, bangladesh is in a potentially catastrophic hotspot of various natural calami- ties, including floods, cyclones, storm surges, salinity intrusion, extreme temperature, drought, etc. , however, burning of fossil fuels worldwide for power generation will, in time, inten- sify these types of threats alarmingly. renewable energy sources are regarded as a promising solution of these pivotal issues. although the solar home system (shs) has spread out to some extent in rural areas of bangladesh, contrariwise, the high price of solar systems and the low efficiencies of solar panels mean that the shs certainly cannot be deemed as an outright solution for the underprivileged populaces of rural communities. , besides, only % of the total population of urban areas gets access to a natural gas cooking facility and most of the rural areas are without any natural gas supply. those rural people mainly utilize wood and kerosene for cooking and lighting requirements which, at the end of the day, triggers oblit- eration of green territory and precarious environmental impacts. in a biogas based research in bangladesh, the authors report that bangladesh has an enor- mous biogas resource potential with its about � poultry fowls in over poultry farms. hardly any biogas plants have been installed in these farms till date, so the possibility of electricity generation has been estimated to have the potential of producing . twh of - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : electricity per year from the poultry industry. the investigation also summarizes the impact of different factors on production of biogas in different biogas plants of bangladesh ranging from . m to m capacity and concludes that % more biogas can be achieved from well- equipped biogas plants with modern controlling stratagems. but the cost factors associated with providing such control systems deter the rural people from adopting these types of plants. because the power systems in poultry farms are anticipated to operate in generally isolated locations with no alternative supply, they must be safe and reliable under all operating condi- tions. hence, the authors in a parallel study examined the power system stability of a stand- alone poultry based biogas plant of bangladesh under different operating conditions using software simulation. a research on off-grid electrification carried out for rural bangladeshi areas, but the capacity of those ranged from to kw, which is a major constraint for these systems as electricity demand cannot be so severely limited for proper rural development. the proposed energy neutral home (enh) is a system where the homes are clearly energy neutral by meeting their energy demand via renewable energy resources devoid of taking elec- tricity from grid. the enh may well provide abridged costs for infrastructure, such as line capacity and peak load generation facilities, plus abbreviated network losses and also promote long-term energy supply security. , the energy neutral home system (enhs) is developed from bangladesh perspective and is aimed at two cases: (i) enhs with only biogas for a single home, which results in a per kwh electricity generation cost of . bdt (bangladeshi taka) which would be less for a larger collective of houses in an area, (ii) hybrid enhs using bio- gas and solar panels collectively as input renewable energy sources, which is found to be more cost effective in urban areas, yielding a per kwh electricity generation cost of . bdt. the study also indicated that this per unit cost is lower than the enhs design based on a solar sys- tem alone, but is still not cost effective for rural areas. in another research, it is revealed that an enhs is significantly beneficial for load shedding backup in urban areas using human waste and found to be more advantageous than the widely used instant power supply. but this sys- tem is not pertinent in rural areas as those are completely without electricity, which does not validate the question of load-shedding. additionally, there are no high-rise buildings in rural areas; hence, human waste collection is not feasible as indicated in the research. in this paper, an effectual biogas based enhs system is developed to light rural areas, provide ample cooking gas and bio fertilizer, thereby supporting sustainable rural development by using readily available cow and poultry manure as the primary sources of energy. this system also contributes to ghg balancing and promotes a healthy and clean living environment. this research is designed for a community of houses such that they obtain the basic needs of modern life; it is an extension of earlier work on the enhs accomplished for a standard home. from the experimental and mathematical analysis, it is clearly evident that the proposed enhs not only reduces the cost of energy generation, but also assists in the reduction of the energy crisis and global warming. per unit electricity production price of this proposed system is . bdt ($us . [ bdt¼$us . is considered]) and the distribution price is considered at . bdt ($us . ), which is lower than the present tariff rate. as rural people are dependent on agriculture and fishing for living, slurry of this system can be used as high quality biofertilizer in fields and as fish food in fishing farms. though this system is designed for bangladeshi rural areas, it can be implemented anywhere around the world where needed. the research will thus generate new knowledge on how an enhs can be a viable and efficient solution to facilitate the provision of electricity to rural communities around the world, not only ameliorating the energy and environmental crises, but also adding value in areas of the economy and sustainable development. ii. materials and method the proposed enhs is designed for a rural community of bangladesh, which includes a farming business where nearby houses are considered as the consumers. this system basi- cally comprises a biogas plant having an inlet chamber, a digester, and an outlet or hydraulic chamber as presented in the block diagram of the enhs shown in figure . the gas production - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : rates of chicken and cow manures are . m /kg and . m /kg, respectively, which are comparatively higher than other waste sources. , hence, this system considers chicken and cow manures as the primary waste sources from a farm having thousand layers (these are the chickens which lay eggs and their waste contain high total solid (ts) value) for biogas gen- eration and cows for optimum performance. manures are fed to the inlet of the plant, mixed with water at an appropriate ratio and sent to the digester. the biogas produced by means of the ad process is collected through a specially designed purifier and processed into both a biogas generator and a cooking gas line. electricity is distributed to the houses through transmission lines associated with control and protective circuitry. for cooking purposes, specially designed burners are used whose gas nozzles are bigger than usual as biogas pressure is lower than with natural gas. after digestion, the waste eructates from the digester to an outlet or hydraulic chamber in wet slurry form owing to high gas pressure in the top of the digester. this can be used for fish feeding directly and the dry slurry can be used as bio-fertilizer in agriculture after necessary processing. a. system demand and management plan to determine energy demand and other managerial specifics, a standard home of a rural bangladeshi region is considered as the analytical base of the proposed research. the gas con- taining capacity of that standard energy neutral home is m , which is used for both cooking and electricity generation purposes in the proportion of % and %, respectively. the total energy demand of that system is w, which is also considered as the benchmark for the proposed enhs with the inclusion of computer provision and slight tweaking in load configura- tion as demonstrated in table i. the expected load curve for electricity supply of a standard home is displayed in figure . the total estimated daily electricity demand for the proposed enhs of a rural community of houses is . kwh and the corresponding load curve is depicted in figure . this assumption is made according to the load condition of a standard home combined with consid- ering some other factors, viz., financial condition, family size (number of family members), size of houses, etc. although the system includes a standard home rating, given the factors fig. . block diagram of the proposed enhs. - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : stated above, not all homes use a refrigerator, computer, etc., which may establish a variation in the load assumptions of figure . the load curve discloses that maximum electricity demand is . kw in the peak hours from pm to pm. by and large, . kwh electricity generation entails m biogas and a biogas burner requires . m of biogas for a hr cooking period. the enhs scope considers two biogas burners for . hr of cooking for a family per day, which amounts to m biogas. hence, for the total community, the required biogas for electric- ity generation is . m and cooking gas is m per day. therefore, the percentages of biogas usage for electricity generation and cooking of the designed enhs are % and %, respectively, as shown in figure . b. system design the main part of the entire system is the biogas plant and its two core components are the digester chamber and hydraulic chamber. schematic design details of the biogas plant are exhibited in figures and . the various design parameters are listed in table ii. manure from cow/poultry farms is fed to the inlet via a waste storage chamber and mixed with water at ratios of : and : for cow and poultry wastes, respectively. a water supply system is assimilated with the inlet to supply essential water during the mixing process. a specially designed mixer, coupled with a motor, is set in the interior of the inlet chamber and is used to blend the diges- tate to yield the anticipated total influent by dint of an appropriate control system. the total load of this mixing system is assessed as kw in light of four -a induction motors each of hp, rpm, plus a water pump of . hp and hr mixing time per day. the coupling of motor to impeller shaft is via a gear box of ratio near to : for operating the mixer at around rpm to ease the mixing process; else the apt mixing is not achievable, i.e., the mixing time increases with lower rpm and, for higher rpm, the mixing mechanism may collapse. the total table i. energy demand of a standard home for the proposed system. load rating (w) number total power (w) energy saving bulb energy saving bulb energy saving bulb ceiling fan color tv refrigerator computer – total fig. . load curve for electricity supply of a standard home. - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : fig. . proportion of biogas for electricity generation and cooking. fig. . load curve of the enhs for a community. fig. . schematic diagram of biogas plant. - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : mixed influent is channeled throughout a manual shutter to the stone settle pit, from where the detrimental contents of poultry or cow manure such as small stones, snails, etc., can be readily removed before the entry of digestate to the digester dome, thus extending the life time of the digester. the generated biogas is drawn from the gas collecting chamber of volume vc, as indi- cated in figure . the wet slurry from the hydraulic chamber exits automatically to the slurry pit whose construction should be such that facile collection of dry slurry is possible (usually the length should be double the height). for an optimum design of the plant, some factors are fig. . measurement parameters of digester. table ii. design parameters of the biogas plant. list of design parameters vi¼volume of inlet f extent of upper parabolic chamber of digester vc¼volume of gas collecting chamber f extent of lower parabolic chamber of digester vgs¼volume of gas storage chamber hi¼clearance between lower level of both inlet and stone settle pitvf¼volume of fermentation chamber vs¼volume of sludge layer h ¼clearance of inlet pipe from flexible cover of stone settle pitvh¼volume of hydraulic chamber vsp¼volume of stone settle pit h ¼level of stone settle pit from insertion point of inlet pipe to digestervws¼volume of waste storage chamber vw¼volume of water tank h¼height between lower level of gas storage chamber and sludge layerv ¼volume of upper parabolic chamber of digester v ¼volume of middle cylindrical portion of digester h ¼height of the hydraulic chamber from digester manure level;v ¼volume of lower parabolic chamber of digester v¼total volume of the digester¼vcþvgsþvfþvs h¼height of the hydraulic chamber to lower level of gas storage chamberdi¼diameter of inlet d¼diameter of digester hh¼height of the hydraulic chamber dh¼diameter of hydraulic chamber hss¼height of the slurry pit r ¼radius of upper parabolic chamber of digester wss¼width of the slurry pit r ¼radius of lower parabolic chamber of digester lss¼length of slurry pit h¼inclined angle of inlet pipe - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : presupposed, viz., vws > vi, vw�vws for cow waste and vw� vws for poultry waste according to the mixing ratio, vsp�vi / , lss� hss, etc. design parameters of the biogas plant are com- puted considering these prerequisites along with infrastructure development company limited (idcol) standards, but the parameters may diverge depending on the plant location. geometrical assumptions for digester design calculations are displayed in table xii in appendix a. for continuous system operation, three different digesters, each containing layers and another fourth digester with cows are deemed necessary. hydraulic retention time (hrt) at �c temperature is considered as days. kg and g manure are obtained per day from each cow and layer, respectively. , ts percentages of fresh discharge are % and %, respectively, and total influent is calculated considering % favorable condi- tion of ts value. according to these standard data and using table xii in appendix a and eq. (b ), design calculations of digester and hydraulic chamber for both cows and layers are presented in table iii. the assumed value of inclined angle of inlet pipe, h, is the same for all digesters of the system and its value is �. the rest of the design parameters revealed in figures and are appraised based on assumptions which may vary on account of the geographical location of the plant. thus, the system is optimized based on available litera- tures, practical implementation, associated technologies and necessary assumptions. according to the above calculations, an overview of the plant, including inlet, outlet, and digesters, with generators in combination, are detailed in figure where all evaluated design parameters, generator capacities and running times, and generators’ connections with the spe- cific number of digesters are portrayed. figure exhibits the overall supply connection of digesters-generators-users and digesters-common biogas line-users. the generated electricity and biogas of the enhs are delivered to the users from the generator block through a common grid line and common biogas line, respectively. biogas comprises some undesirable impurities, viz., h s, moisture, vapor, etc., which must be removed before consuming the gas. amongst these, h s is the most problematic, since it is toxic as well as corrosive. although the proportion of h s in biogas composition is very low ( – %), even its slight presence can cause some damage to the generator and hence lowers the system life time while environmental aspect is beyond the discussion. , hence, a special- ized purification unit is employed in the system, as shown in figure , which contains cham- bers. , chamber is known as the water trap and it sucks the water content from the biogas. chamber acts as a simple filter, which has a pipe inside with a certain height and span where the biogas strikes to the inside wall. hence, the water content of biogas is detached and stored table iii. volume calculation data of digester and hydraulic chamber. parameters value cows layers (hydraulic chamber) total influent (q) kg kg parameters value water to be added kg kg cows layers working volume m m vs . m m (digester) vgs m m vdis m m v m m gas chamber volume . m . m d . m . m pi kpa kpa h . m . m pf . kpa . kpa f . m . m h . m m f . m . m h . m . m r . m . m hh m m r . m . m dh . m . m v . m . m vc . m m - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : at the bottom of the chamber. the stored water is removed using a tap under chamber after six months. chamber holds iron (fe) chips and it is the most significant portion, as this chamber eliminates the noxious h s according to following reaction: fe þ h s ¼ fes þ h . fig. . overview of the enhs for a community of homes. fig. . enhs for rural community. - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : chamber has silica gel within it and removes vapor or moisture from the biogas. iron chips are inspected at least twice a year and regenerated or replaced if required, depending on its condition, whether it is fully oxidized or not. on the other hand, the silica gel is inspected quarterly every year and replaced when its original color changes, which depends on biogas flow rate through the purifier. the design parameters of the biogas purifier are denoted in figure , where lp and lp are spans of the respective chambers, lp is height of inlet pipe placement, lp is span of inlet pipe into chamber , dp and dp are the diameters of the cylindrical chambers. these are assumed such that lp � lp / , lp is slightly less than overall diameter dp , dp > dp , and lp > . lp , which vary with digester size and generator capacity. table iv indicates gas production capacity (vgs) of each of the three chicken manure digesters is m and the fourth one for cow manure is m , which sums the total gas pro- duction capacity of the system as m and indicates generator capacities for the best per- formance. gas generators for generating electricity from biogas are reliant on load demands around different times as displayed in figure . figure explores generator operating sched- ule at different times to meet the pivotal load demand of this system in an assured way. the graph in figure presents electricity generation by the system for hr according to the schedule periods of figure . as generator is dedicated for running inlet systems and other auxiliaries, it is not included in further load analysis. the test case prototype of this developed enhs is implemented (as shown in figure ) for a standard home at mr. anil kanti das’s residence, located in rangunia, chittagong, bangladesh. figure provides some photographs of the implemented prototype. an area within a km radius is assumed, including families, as a test case area for this system. the fig. . schematic diagram of biogas purifier used in the enh system. table iv. digester vs. generator capacity. digester no. designed for gas production capacity(m /day) generator no. generator capacity (kw) layers gen- layers gen- gen- layers gen- cows gen- (sum¼ m ) gen- - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : fig. . effective working time of generators. fig. . generator scheduling. fig. . electricity generation over a day. - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : analysis and related design calculations are made based on the practical data from this proto- type, gtz (deutsche gesellschaft fur technischezusammenarbeit) and idcol bangladesh. , iii. result and analysis net present value (npv) and payback period analysis are used to determine economic via- bility of the model. the equation for npv is presented in the following equation: , npv ¼ xn t¼ cft þ kð Þt : ( ) here, cft¼cash flow of the investment in time period t; k is the discount rate; and t is the time period from to n years. again, payback period (pbp) is calculated as pbp ¼ cinit = cin; ( ) where cinit¼ initial investment and cin¼annual cash inflow. all costs are estimated based on vendor’s retail price. , taking the total life time of this enhs for a rural community to be years and given the cost of a cft (cubic foot) [ m ¼ . cft] digester is about bdt ($us ), brief digester costs in addition to hydraulic chamber and inlet recharge chamber costs are set out according to figure , which results in a total cost of bdt ($us ) to construct the stated four digesters. the purification system cost is dependent on digester size plus generator capacity and is determined according to market prices of bdt ($us ) for each digester for layers and bdt ($us ) for the digester for cows. the model requires stone settle pits of bdt ($us ) each and waste storage chambers of bdt ($us ) each. cost for mixing system ¼ �ð hp induction motor þ gear boxðfor motor controllingÞþ impellerÞ ¼ �ð þ þ Þbdt ¼ bdtð$us Þ: cost for water supply system ¼ : hp water pumpþ � l water tanks½for digesters ; and � þ l water tank½for digester � ¼ þ �ð � Þþ � bdt ¼ bdtð$us Þ: fig. . implemented energy neutral home system. - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : complete purification cost for this model is estimated as bdt ($us ) and pipeline and other costs as ($us ). total plant cost (tpc) is thus determined as bdt ($us ), and the detailed cost calculations are tabulated in table v. for long term operation, additional costs comprising top overhaul cost and major overhaul cost along with the ongoing repair cost should be reckoned. top overhauling is entailed after hr of generator operation that costs % of gcost and the major overhauling has to be done after a further hr of operation at a pricing of % of gcost. total operating cost for the system taking into account overhaul and repair costs of the generators is bdt ($us ) as analyzed in table vi. from figure , electricity used in a day is calculated as . kwh to meet load demand. additional kwh electricity is also required to keep the inlet, mixer, and water supply system running. the total required electricity generation per day is . kwh, which requires . m biogas. m biogas is necessary for cooking purpose of families considering m /day gas demand to each family. in accordance with the percentage split of biogas consumption, as shown in figure , cook- ing gas generation cost encompasses % of total biogas generation and supply related costs while the cost of electricity generation is estimated considering % of total biogas generation costs together with generator, transmission line, and other circuitry costs. cooking gas generation cost ¼ % of digester cost þ % of inlet system cost þ % of purification cost þ pipelining cost ¼ bdt � $us per unit cooking gas generation cost ¼ cooking gas generation cost = total gas generation in years ¼ : bdt � $us : ðper m Þ electricity generation cost¼ % of digester costsþ % of inlet system costþ % of purifier costþgenerator costþ total operating cost of generatorsþ transmission line and other circuitry costs¼ bdt�$us . per unit electricity generation cost¼electricity generation cost / total electricity generation in years¼ . bdt�$us . (per kwh). monthly cooking gas bill is assumed bdt (�$us . ) for each family. the daily electricity consumption varies from home-to-home due to the socio-economic conditions of rus- tic people. the monthly income of the enhs for electricity consumption with a rate of . table v. total plant cost of the designed model. sl capital cost item bdt digester construction hydraulic chamber and inlet construction stone settle pit waste storage chamber mixing system water supply system purification unit pipeline and others generator cost subtotal plant cost (spc) [ þ þ þ þ ] ($us ) transmission line and protective circuitry ( % of spc) total operating cost of generators total plant cost (tpc) ($us ) - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : bdt (�$us . ) per kwh is detailed in table vii, and the yearly revenue of the system is enumerated in table viii. as the system incorporates the employees of the farming business into the enhs also, it does not require more workers for system management. however, the system employs two laborers at bdt (�$us ) each per month and an accountant at bdt (�$us ) per month on a fulltime basis. the total operating cost (toc) of the model is summarized in table ix, and all investments, expenses, and earnings are briefed in table x. finally, the fi- nancial evaluation of the proposed model is calculated and presented in table xi, which results in the system being economically viable. iv. discussion this study developed an enhs for rural communities which will not only play an active role in reducing the energy crisis and costs of energy generation worldwide, but also reduces greenhouse gas emissions into the atmosphere. from the study, it can be clearly demonstrated that the proposed system will be beneficial to society in a number of ways, which are presented in subsections iv a–iv h. a. case- : retail price of electricity according to the retail tariff plan of the rural electrification board (reb) for the fiscal year – , the per kwh electricity price for domestic users is . – . bdt, and including line charge and all other service charges, it becomes . bdt, which is proposed to increase from % to . % depending on the load level. but load shedding is a very com- mon hazard in rural areas and no new electricity connections are allowed. in this enhs, elec- tricity price is estimated as . bdt per kwh, which is lower than the reb tariff with the enhs providing assurance of supply continuity and reliability. the costs of electricity from table vi. generator overhaul and repair costs. gen. no. operating time (hr) top overhaul major overhaul total overhaul cost (bdt) total generator overhaul cost (bdt) repair cost (bdt) total operating cost of generators (bdt) required times total cost ( % of gcost each time) (bdt) required times total cost ( % of gcost each time) (bdt) gen- ($us )gen- gen- gen- gen- gen- … … table vii. monthly electric bill calculation. house no. electricity consumption/day (kwh) per unit rate (bdt) monthly bill (bdt) total monthly electric bill (bdt) – . ($us ) – – . – – . – – - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : other renewable sources are much higher, viz., electricity from solar system costs . bdt (�$us . ) per kwh. b. case- : per unit electricity generation cost it has been seen from the results that the electricity generation cost for this system is . bdt covering transmission and distribution costs. however, the per unit cost of electricity gen- eration for recently available quick rental power plants (qrpps) and independent power producers (ipps) is . to . bdt and . to . bdt, respectively, from natural gas while it is . to . bdt and . to . bdt, respectively, from furnace oil. government is subsidizing this sector to provide electricity at reasonable prices, which costs a huge amount of the budget every economic year. the country subsidizes in two categories, power generation and distribution. the first step reduces the generation cost to an average of . bdt per kwh, and the second step minimizes the distribution tariff to consumers, which was a cost to the national budget of . � $us in . table x. summary of investment, expenses, and earning. investment (tpc) yearly income yearly expenses (toc) yearly earning ($us ) table xi. financial evaluation of the proposed system. discount rate % payback period (pbp) years . npv, years bdt net profit bdt ($us ) table viii. yearly revenues from the model. revenues bdt/month bdt/year cooking gas charge electric bill total revenues ($us ) table ix. summary of total operating cost (toc) of the system. item cost item bdt/year fixed operational cost (foc) personnel cost overheads variable operational cost (voc) repair and maintenance total operating cost (toc) ($us ) - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : c. case- : lighting (enhs vs. kerosene) people usually use kerosene for lighting purposes in rural areas, which costs almost – bdt per month for a standard family and also causes environmental as well as health hazards due to kerosene burning at home. in this system, electricity supply from the renewable source abolishes this kerosene cost and safeguards the healthy environment at home. lighting of houses, schools, etc., of remote areas with the enhs gives rural kids and students better conditions for study and hence they can utilize their time effectively, which finally leads to social development of rural areas. d. case- : cooking benefits the present tariff rates of single and two burner stoves are bdt and bdt, respec- tively. but recently a price increment proposal of bdt for two burners and bdt for one burner was submitted to the bangladesh energy regulatory commission, being . % and . % increments, respectively. a survey in a village pomra, rangunia, chittagong, bangladesh, reveals that the cooking wood cost for a typical family is around bdt/ month while liquified petroleum gas (lpg) costs around bdt/month. again, some peo- ple use kerosene stoves for cooking, which costs almost bdt per month. in this system, the cooking gas price is fixed at bdt, which is cheaper than the current cooking cost in a rural area considering the factors as stated above. therefore, this enhs provides a significant saving from cooking gas usage. as can be predicted from the statistics, , there is no chance of a natural gas supply facility being available in rural areas in the foreseeable future; hence, this enhs brings this facility to rural people along with good financial savings, which finally leads to the socio-economic development of rural communities of bangladesh. this cooking gas facility additionally ensures a healthy cooking environment and saves cooking wood collec- tion time, which leads to rural life development. in such instances, the mothers will get more hygienic cooking conditions which will reduce the probability of food poisoning and sickness, particularly among poor children. therefore, enhs will be a wonderful solution in rural areas of bangladesh where the potential of biomass and biogas energy sources is enormous. e. case- : environmental impact natural gas required for kwh electricity generation is cft. consequently, this system generates a total of . kwh electricity for consumer supply with biogas which saves cft of natural gas resources per day. furthermore, per kwh electricity production from natural gas emits a maximum g co to the environment which would cause about . kg co emission per day to serve this rural community system demand using natural gas, while a maximum . kg co is emitted by electricity generation from biogas in this pro- posed enhs. , in rural areas, usage of non-purified biogas containing h s is evident from the fact that tin shaded rooftops of kitchens are damaged very quickly with burning and hence introduces extra cost, hazards, etc. again, it stimulates oxides of sulfur while burning which ultimately prompts severe acid rain and serious greenhouse effects. it also reduces generator lifetime significantly, and gi pipeline is damaged very early if the supplied biogas contains even a small portion of h s. however, in this system, biogas is purified with the removal of h s as it is a very perilous component of biogas for generator and cooking. consequently, this system will reduce the emission of ghgs from the generation sector as well as the residential sector, which will diminish global warming and climate changing impacts. f. case- : ease of waste management as the business of poultry and cow farming is spread through rural areas along with the system, it makes the waste management of the farm easy and profitable. in large scale poultry and cow farms, massive amount of wastes are created every day, which are incredibly difficult to dispose of in an environment-friendly way. in rural areas of bangladesh, these fresh wastes - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : are openly used as biofertilizer on crops, which is not useful focusing various factors as dis- cussed in this research. however, such fresh wastes require a lengthy period to turn into a fertilizer and, in the course of this open digestion process, the high methane content of those fresh wastes causes times greater greenhouse effects than of a co molecule. from that point of view, this system introduces an environment-friendly way of appropriate waste man- agement. an attractive benefit of this system for rural people is that the raw slurry discharged from the digester outlet can be used as fish nutrition in pond or fish farm adjacent to the plant, and also as quality biofertilizer , – in agriculture. g. case- : social impact in this research, provision for using computers in a rural community where electricity has not yet reached may not seem appropriate, but bearing in mind the country’s goal of exploiting modern technological advancements and telecommunications, it is readily foreseeable that, if proper amenity is bestowed to these diligent and talented rural people, this will create a signifi- cant difference and there will be a technological revolution countrywide. as electricity is a key factor to improve medical services in remote areas, implementation of a system like this permits vaccination, sterilization, and surgery, and hence, an improvement over time in the quality of the medical services will be possible. these better working conditions may attract more qualified doctors and nurses to work in rural environments. moreover, this system creates job opportunities for rural people as plant operators, accountants, etc., generates opportunities for both small and large businesses outside the heavily populated cities of the country by dint of improved accessible amenities and, as a consequence, the enhs helps to diminish poverty. h. case- : reduction of deforestation the cooking wood requirement for a standard family per year is . tons. thus, this system saves the community tons per year of wood from household cooking, which in turn saves a large amount of trees from being cut down. again, these saved green trees will reduce ghg effects on the environment in a substantial way and assist with greenhouse gas balance. v. future research scopes the comprehensive model will yield a sensible and simplified platform that provides the detailed information for possible deployment of an enhs for rural communities not only in bangladesh but also in other countries around the world. this study is still in its preliminary phase and so there is an ample scope for ancillary research on this system in the following areas: • development of simulation model to validate the experimental and mathematical analysis. • development of enhs based chain business model for a rural community. • development of enhs in larger scale. • enhs with more enhanced purification capacity. • updating of the system considering other socio-environmental factors. • enhs design for urban areas where a vast quantity of municipal and human waste is available. vi. conclusion energy crisis in the rural areas, costs of energy generation, and environmental awareness have encouraged interest to generate more energy from renewable energy sources either through off-grid or grid connected systems. therefore, in line with the current initiatives, this study developed the methodology for a reliable and efficient enhs that can provide reliable and uninterrupted power supply to a rural community. this research presents a new and applicable solution to assist rural communities by providing affordable renewable energy, cooking gas, high quality fertilizer, job opportunities, and environmental safety, and hence enhance the over- all scope for the sustainable development of rural life. this designed system can produce - das et al. j. renewable sustainable energy , ( ) reuse of aip publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. downloaded to ip: . . . on: sat, mar : : . kwh electricity per day, sufficient for houses, which is greatly profitable for plant owners. this system not only provides energy at least cost but also ensures environmental safety as well as high quality fertilizer for agriculture and fishing. this system provides gas to rural people for cooking which in fact saves green territory. therefore, to overcome energy cri- sis and improvise large rural communities of bangladesh as well as other countries alike, this community based energy neutral home system can be a reliable and effective solution. appendix a: geometric assumptions of digester calculations see table xii. appendix b: boyle’s law • the normal pressure of the digester¼pi. • the final pressure of the digester¼pf. • according to boyle’s law, for pressure calculation of hydraulic chamber, pi �ðtotal gas produced þ : Þ¼ pf � : : (b ) international energy agency, see http://www.worldenergyoutlook.org/resources/energydevelopment/energyaccessdata- base/ for iea-energy access database-world outlook (last accessed april ). a. schmidt, b. e. law, c. hanson, and o. klemm, atmos. clim. sci. 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http://www.eia.gov/tools/faqs/faq.cfm?id= &t= http://www.icbe.com/carbondatabase/co volumecalculation.asp http://dx.doi.org/ . / - - - - _ http://dx.doi.org/ . /j.agee. . . http://dx.doi.org/ . /j.biombioe. . . http://dx.doi.org/ . /j.biombioe. . . http://dx.doi.org/ . /s - ( ) - http://dx.doi.org/ . /j.wasman. . . http://dx.doi.org/ . /s http://dx.doi.org/ . /s - - - http://dx.doi.org/ . /s - - -z http://dx.doi.org/ . /j.biombioe. . . https://www.researchgate.net/publication/ hepatic encephalopathy in the st century: still an emerging topic journal of clinical medicine editorial hepatic encephalopathy in the st century: still an emerging topic lorenzo ridola * and oliviero riggio ���������� ������� citation: ridola, l.; riggio, o. hepatic encephalopathy in the st century: still an emerging topic. j. clin. med. , , . https://doi. org/ . /jcm received: january accepted: january published: january publisher’s note: mdpi stays neu- tral with regard to jurisdictional clai- ms in published maps and institutio- nal affiliations. copyright: © by the authors. li- censee mdpi, basel, switzerland. this article is an open access article distributed under the terms and con- ditions of the creative commons at- tribution (cc by) license (https:// creativecommons.org/licenses/by/ . /). department of translational and precision medicine, “sapienza” university of rome, viale dell’università , rome, italy; oliviero.riggio@uniroma .it * correspondence: lorenzo.ridola@uniroma .it why write about hepatic encephalopathy (he) in the twenty-first century? it is in front of this question that we found ourselves, once invited to serve as guest editors for the special issue of the journal of clinical medicine entitled “hepatic encephalopathy: clinical challenges and opportunities”. scientific research has made important advances, the pathogenesis of he is more deeply known, and the role of toxins such as ammonia (still relevant!), as well as those of systemic inflammation, are being discussed, even in a very heated way. overt he has been deeply defined, while the minimal hepatic encephalopathy (mhe) (and covert) are becoming increasingly important, due to the high impact on the daily life both of the patient and caregiver. progress is also remarkable regarding the pharmacological approach. in fact, secondary prophylaxis appears to be consolidated and effective, while for episodic he, the importance of identifying and treating precipitating factors, as an “ideal first cause” of he, is now affirmed and widely accepted [ – ]. nonetheless, there are still many gray areas and issues that need further study, especially regarding the role of treatment in patients with minimal he [ – ]. in fact, in this specific setting, guidelines suggest treating patients on a case by case basis. more generally, the ideal design of therapeutic studies also remains debated. in fact, the existing literature on he medical management still suffers from a lack of standardization, and this heterogeneity makes the pooling of data difficult or meaningless. there is still an unmet need for “robust” controlled clinical trials on treatment effects on he, because decisive clinical studies are few, although the number of patients and their resource utilization remain high [ ]. in this special issue, it was therefore decided to give space to contributions addressing the most innovative topics in he. the pathogenesis of he is, indeed, not completely clear. a series of observations, based on clinical and therapeutic features, suggest that for any substance to be involved in the pathogenesis of he, it should originate in the gut, possibly by the action of bacteria, be found in the portal circulation, be increased in peripheral blood as a consequence of failing liver or portal systemic shunting, and finally should exert its effect on the brain. unfortunately, any attempt to clarify the nature of the substance(s) involved has, until now, not been completely satisfactory. ammonia meets all the above mentioned criteria, but its correlation with he is not always found. because of these considerations, the role of other potential toxins, such as tryptophan derivatives, has been investigated over the years [ ] and the effects of systemic inflammation and its mediators have been better studied. however, even today, ammonia plays a predominant role in the pathogenesis of he and this is also confirmed by the effectiveness of treatments aimed at ensuring the metabolism or the prompt elimination of nitrogen derivatives. there is growing interest in the modulation of the gut–liver–brain axis in the therapy of complications of liver cirrhosis, including he. fecal transplantation in this setting of patients has also recently been proposed with encouraging results [ , ]. this certainly represents a new frontier in the management of advanced liver diseases. concerning he pathophysiology, in this issue, the relationship between hepatic dysfunction and the progression of brain energy crisis in hepatic encephalopathy has also been addressed. j. clin. med. , , . https://doi.org/ . /jcm https://www.mdpi.com/journal/jcm https://www.mdpi.com/journal/jcm https://www.mdpi.com https://doi.org/ . /jcm https://doi.org/ . /jcm https://creativecommons.org/ https://creativecommons.org/licenses/by/ . / https://creativecommons.org/licenses/by/ . / https://creativecommons.org/licenses/by/ . / https://doi.org/ . /jcm https://www.mdpi.com/journal/jcm https://www.mdpi.com/ - / / / ?type=check_update&version= j. clin. med. , , of another unsolved problem, which still heavily complicates the management of cir- rhotic patients with portal hypertension, is the occurrence of he after transjugular intrahep- atic portosystemic shunt (tips) placement. a tips is widely adopted to treat complications of portal hypertension such as recurrent variceal bleeding or refractory ascites, by shunting blood flow, bypassing the liver and, consequently, reducing portal pressure, with the aim to reduce mortality and bridge patients to liver transplant. tipss represent often a life- saving procedure, but are characterized, due to the blood diversion directly into systemic circulation, by the development of he, particularly in the first period immediately after the procedure. to date, the role of drug therapy in prophylaxis of he after tips is not yet clear and supported by strong scientific evidence [ , , ]. more recently, approaches characterized by modulation of the stent caliber or choosing reduced caliber shunts have also been proposed [ – ]. however, even this evidence does not yet allow us to formulate sufficiently “robust” recommendations and the choice to close tipss for refractory he is very hard and needs to be counterbalanced with the competing risk of newly developing those complications of portal hypertension that were the indication to tips placement. re- cently, the role of spontaneous portosystemic shunts (spsss) also appears to be of growing interest, both for the causative role in determining he, and due to the possibility to treat shunt-induced he by closing or reducing the caliber of those collaterals [ – ]. indeed, the search for spsss has entered the process of classification of patients with a history of he. a frequent complication of cirrhosis is malnutrition, which is associated with the progression of liver failure, and with a higher rate of complications, including infections, hepatic encephalopathy, and ascites. it is well known that sarcopenia, a condition in which muscle mass and function are reduced due to the patient’s poor nutrition and reduced physical activity, also has a prognostic impact on cirrhosis and its complications [ ]. a historical dietary approach of encephalopathic patients was characterized by a close protein restriction. nevertheless, recently published european association for the study of the liver guidelines on nutritional management of cirrhotic patients [ ] state that nutritional status and the presence of sarcopenia should be evaluated in patients with he and to avoid protein restriction in patients with he. to date, the relationship between sarcopenia and he looks better defined, as well as the importance of an adequate nutritional intake, but the role of an intervention deserves more convincing results. for example, studies aimed to assess the role of physical exercise in improving sarcopenia and consequently he should, in our opinion, be strongly encouraged. in summary, he is a condition characterized by a heavy burden both on the patient and caregiver, and on health systems. therefore, considerable interest is currently focused on the use of administrative data. this information is available in databases of health care systems, and the retrieval and analysis of these data allow us not only to provide an immediate picture of the dimension of he’s burden, but also to identify prognostic factors associated with the development of hepatic encephalopathy. this knowledge, in the near future, may allow for better stratification of patients at risk and starting early therapeutic interventions. it is therefore time to consider he under a new perspective, in which some different new factors should be considered to have a determinant/causative and prognostic role. indeed, patients at risk for he should be considered, not only those with severe liver disease, or a previous history or with minimal/covert he, or tipss, but also those with sarcopenia, nutritional deficit, or bearing spsss. it is important to consider cirrhotic patients under this whole panorama in order to identify very high-risk patients, in which other factors with a different and non-“classical” management should be respectively searched and adopted. conflicts of interest: the authors declare no conflict of interest. j. clin. med. , , of references . vilstrup, h.; amodio, p.; bajaj, j.; cordoba, j.; ferenci, p.; mullen, k.d.; weissenborn, k.; wong, p. hepatic encephalopathy in chronic liver disease: 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© selection and/or peer-review under responsibility of basel convention coordinating centre for asia and the pacifi c and national center of solid waste management, ministry of environmental protection of china doi: . /j.proenv. . . available online at www.sciencedirect.com the th international conference on waste management and technology preliminary study at lipids extraction technology from municipal sludge by organic solvent fenfen zhua,*, luyao zhaoa, zhaolong zhangb, huimin jianga a school of environment & natural resources, renmin university of china b school of resources environment & tourism, capital normal university abstract with the development of our society, waste water treatment ratio is going higher and as a result there are more and more sewage sludge. because of its high water content, containing heavy metal and some virus, sewage sludge has been a serious environmental problem. considering the energy crisis and serious environmental pollution, and because of the fact that there are considerable lipids in sewage sludge, which can be turned into biodiesel by esterification or transesterification, we proposed a new solution for sewage sludge problem which is to make biodiesel from sewage sludge. the whole process is divided into three steps: heat-drying, extraction of lipids and transesterification. in this research, we are going to discuss the extraction step. we extracted lipids from sewage sludge by referring to the national standard for food. we used many organic solvents such as ether, hexane, acetone, chloroform – methanol. then we will discuss that which solvent will be more favorable to extract the lipids from the sludge by measuring the quantity of the lipids we have obtained. after the experiment, we have found that as to the single solvent extraction, bromo-propane solvent has the highest extraction effect, the other sort of the solvents are ether, toluene, n-hexane, petroleum ether. while, as to mixed solvent extract, the hexane – ethanolthe solvent has higher efficiency than other mixed solvent. the results show that mixed solvent has higher efficiency than the single solvent and the polar solvents are easier to extract more lipids than the non-polar solvents from the sludge. © the authors. published by elsevier b.v. selection and/or peer-review under responsibility of basel convention coordinating centre for asia and the pacific and national center of solid waste management, ministry of environmental protection of china. key words: sewage sludge, organic solvent, biodiesel, lipids extraction . introduction with the rapid development of the society, the over-consumption of the energy has lead to energy crisis. “sustainable development” has been the leading concept for our country and even the world, which * corresponding author. tel.: + - - ; fax: + - - ; e-mail address: zhufenfen@ruc.edu.cn available online at www.sciencedirect.com © selection and/or peer-review under responsibility of basel convention coordinating centre for asia and the pacific and national center of solid waste management, ministry of environmental protection of china. open access under cc by-nc-nd license. open access under cc by-nc-nd license. http://creativecommons.org/licenses/by-nc-nd/ . / http://creativecommons.org/licenses/by-nc-nd/ . / fenfen zhu et al. / procedia environmental sciences ( ) – also asked us to find renewable and environment-friend energy [ ]. biodiesel could be one of the solutions. biodiesel is environmental-friendly and renewable, whose raw materials are from plants and animals. compared with traditional fossil fuels, biodiesel not only has the ability to circulative, at the same time, it also has high-quality combustion performance and safety performance [ ]. but researches shows that the cost of traditional raw materials for biodiesel amount to almost % of the total cost of biodiesel production, which strongly prevent biodiesel to be used widely. so cheaper raw material is demanded [ ]. sewage sludge turned to be suitable substitute. in china the average concentration of organic matter is . % in china, among the total organic, carbohydrates account for %, protein account for %, and lipids account about % [ ]. though the average content of organic compounds in the sludge are lower than the developed countries, in some big cities like beijing the it has been almost at the same level about %. another attractive point is that sewage sludge is zero or even minus cost as raw material. if we can extract all of the lipids from the sewage sludge to make biodiesel, it can bring us huge economic benefits. besides the big amount of sewage sludge, it contains lots of hazardous substances such as pathogens, heavy metals, and even dioxins, which will be harmful to our heath and environment [ - ]. this situation has made disposal problem of sludge becoming the focus of the environmental issues. though there are lots of ways to dispose sludge such as sanitary landfill, incineration, anaerobic fermentation, compost and so on. but as to each method, there are shortcomings, for example, high operating costs of incineration, possible serious secondary pollution of landfill and incineration, abundant land use of landfill, anaerobic fermentation and compost, and others [ ]. because of some these reasons, recycling technology which is consistent to “sustainable development” strategy has been a welcomed trend to treat all waste [ ]. recycling sewage sludge to make biodiesel is one of the recycling technologies and extraction of lipids from sludge is one of the important steps to make biodiesel. we will discuss this research here. according to the complex sources of sewage and the complicated waste water treatment technology, the lipids in sewage sludge should exist in several forms which would make the extraction not easy to operate. however lipids have a common characteristic that they are generally soluble in organic solvents but don’t dissolve in water. and certainly more similar the polarity is, more easily soluble they are [ ]. according to this feature, we can use organic solvents to extract lipids from the sludge. however, the organic solvents might not be simple or the extraction step might be a little complicated. because lipids extraction technology from sludge has not been taken seriously, there is no national standard in lipids assessment for sewage sludge, and we decided to refer to the national standard of the food industry. in the literature review, we have found that some solvents such as ethanol, ethyl ether, petroleum ether, hexane, chloroform – methanol, bromo-propane, hexane – ethanol have been used for extraction lipids [ , ]. besides these solvent we will try more solvents such as dichloromethane, ether-petroleum ether and dichloromethane-methanol to extract lipids from sludge. we want to find out which solvent (single or mixed) will be better to extract the lipids from the sludge by measuring the quantity of the lipids. . experiment materials and methods . . experimental materials: dewatered sludge from one sewage treatment plant in beijing .the moisture content of the sludge sample is %± . %. the experimental instruments we used to check the sludge component were listed in table . and the typical element component of this kind of sewage sludge was shown in table . table . experimental instruments fenfen zhu et al. / procedia environmental sciences ( ) – items instruments metallic element atomic absorption spectroscopy, hitachi, z- tc jena multi n/c s and yena ht solid module cl- ion chromatography, dionex, ics- table . sludge composition items vss(%) tc(mg/g) cl(mg/g) k(mg/g) fe(mg/g) cu(mg/g) zn(mg/g) mn(mg/g) ca(mg/g) pb(mg/g) contents . . . . . . . . . . reagents: hydrochloric acid ( %~ %), ethanol ( %), ether, petroleum ether, acetone, hexane and other organic solvents . . experimental methods [ ]: we adopted the method of gb/t . - , the acid hydrolysis method for determination of fat in foods, but we tried different extraction solution. important steps in gb/t . - : ( ). make the solid sample grind it to a granular can, add ml water and ml hydrochloric acid ( %~ %). put them into the tube and heat it in the water bath of ~ for about ~ minutes; ( ). take out the tube, add ml ethanol ( %) into it, transfer the solution to a ml beaker after cooling the mixture, and then filter the solution in the beaker to the erlenmeyer flask. pour prepared ml ether and ml ether - petroleum ether into the tube to wash the lipids in it, then remove them to the flask together. keep standing for or min, and then remove the supernatant to the flask after the upper liquid is clear. ( ). put the flask (constant weight) on thermostatic electric hot plate to evaporate to dryness for about hours, the temperature will be kept at . at last, we put the flask on the electronic balance to measure the result. however, we made two modifications of the above steps when we did this experiment. the first is that in the second step we transfer the mixture solution into a separating funnel than got the supernatant not by sucking the supernatant out. the second and the most important is that we replaced the original extraction solvent, ether, by other solvents such as petroleum ether, toluene, hexane, isopropyl, chloroform - methanol, ether - petroleum ether, hexane – ethanol. . experimental results and discussion: according to this method, we have tried to extract lipids from the sewage sludge by using various organic solvents with three kinds of sludge sampled in three different times. all experimental results are shown in figure : fenfen zhu et al. / procedia environmental sciences ( ) – br om o- pro pa ne et he r pe tro leu m eth er n- he xa ne di ch lor om eth an e he xa ne -e tha no l di ch lor om eth an e- me tha no l ch lor of or m- me tha no l et he r-p etr ole um e the r organic solvent m as s pe rc en ta ge ( % ) the first the second the third fig. . lipid extraction results from the experiment results, it can be seen that the amount of extracted lipids depends on the solvent used to extract as to the same sludge sample. the amount of lipids we extracted from the sludge sampled in the first time are significantly higher than those samples in the second and the third, which can be possibly explained that the sludge taken for the first time has higher organic matter such as lipids than the other two times. but to each kind of sludge, the tendency is roughly the same: mixed solvent has higher efficiency than the single solvent and the polar solvents are easier to extract lipids than the non-polar solvents. we can explain it like that: there are many kinds of lipids (both polar and non-polar) in the sludge. in primary sludge, the lipids are mainly non- polar because they derived from glyceride in the water. as to the sludge from the secondary sedimentation tank, they have lots of microbial cells, the lipids in whose cell wall are main polar phospholipids. the polarity order of the solvent is that: bromo-propane dichloromethane ether n-hexane petroleum ether. in other words, polar lipids are very possibly more than non-polar in the sewage sludge. . conclusions recycling sewage sludge to be raw material for making biodiesel is a relatively possible choice for big cities to solve the problems of sewage sludge, energy crisis and limited area. referring to the national standard for food industry, we have done experiments to test the extraction of lipids from sewage sludge, which is the very important step for biodiesel making. we got the following conclusions. as to the single solvent extraction, bromo-propane solvent has the highest extraction effect, hen followed with ether, toluene, n-hexane, petroleum ether. while, as to the mixed solvent extraction, the hexane – ethanolthe solvent has higher efficiency than other mixed solvent such as ether – ethanol and chloroform – methanol. compared with single solvent extraction, the mixed solvent has higher efficiency. . acknowledgment this research is supported by the basic research funds in renmin university of china from the central government ( xnlj ). fenfen zhu et al. / procedia environmental sciences ( ) – references [ ] wang hongyan , li jingmin, zhao qun , lin yingji, resources and development of new energy in china, acta petrolei sinica, , ( ): - [ ] wang cunwen, production technology of biodiesel and some examples, chemical industry press, , [ ] lu qinghua,zhu qing, he zuoyun, the availability of raw materials of biodiesel and the cost analysis,petroleum & petrochemical today, , ( ): - [ ] zhang weijun, study on the municipal sewage sludgethermal drying characteristics and energy consumption, a thesis submitted to chongqing universityin partial fulfillment of the requirement for thedegree of master of engineering. [ ] kong xiangjuan, disposal technology status and development trend of municipal sewage treatment plant sludge treatment in china [ ] guo guanghui, heavy metals and nutrients in sewage sludge from different areas in china and its potential argucultural landuse, applicant for master degree. [ ] li yanxia, chen tongbin, luo wei, huang qifei, wu jifu, contents of organic matter and major nutrients and the ecological effect related to land application of sewage sludge in china, acta ecologica sinica, , ( ): - [ ] li bing, yin qingmei, zhang hua, shi lei, zhao youcai, methods of sludge treatment and disposal and resource utilization, safety and environmental engineering, , ( ): - [ ] liang jinli, meng yuzhu, lei changgui, locust lipids,extraction and component investigation , journal of the chinese cereals and oils association, , ( ): - [ ] lu lili, chen shunsheng, comparison onmethods of extracting lipids from roes of carassius auratus, journal of shanghai fisheries university, , ( ): - [ ] han ju, luo min, gao wenhui, research progress methods of lipids extraction from food, he bei journal of industrial science & technology, , ( ): - [ ] national standard of people's republic of china, the determination of fat in food, gb / t . - reconfiguration of n metabolism upon hypoxia stress and recovery: roles of alanine aminotransferase (alaat) and glutamate dehydrogenase (gdh) plants review reconfiguration of n metabolism upon hypoxia stress and recovery: roles of alanine aminotransferase (alaat) and glutamate dehydrogenase (gdh) houssein diab and anis m. limami * university of angers, umr irhs, sfr quasav, bd lavoisier, f- angers, france; drhd @hotmail.com * correspondence: anis.limami@univ-angers.fr; tel.: + - - ; fax: + - - academic editor: maurizio chiurazzi received: march ; accepted: may ; published: may abstract: in the context of climatic change, more heavy precipitation and more frequent flooding and waterlogging events threaten the productivity of arable farmland. furthermore, crops were not selected to cope with flooding- and waterlogging-induced oxygen limitation. in general, low oxygen stress, unlike other abiotic stresses (e.g., cold, high temperature, drought and saline stress), received little interest from the scientific community and less financial support from stakeholders. accordingly, breeding programs should be developed and agronomical practices should be adapted in order to save plants’ growth and yield—even under conditions of low oxygen availability (e.g., submergence and waterlogging). the prerequisite to the success of such breeding programs and changes in agronomical practices is a good knowledge of how plants adapt to low oxygen stress at the cellular and the whole plant level. in the present paper, we summarized the recent knowledge on metabolic adjustment in general under low oxygen stress and highlighted thereafter the major changes pertaining to the reconfiguration of amino acids syntheses. we propose a model showing (i) how pyruvate derived from active glycolysis upon hypoxia is competitively used by the alanine aminotransferase/glutamate synthase cycle, leading to alanine accumulation and nad+ regeneration. carbon is then saved in a nitrogen store instead of being lost through ethanol fermentative pathway. (ii) during the post-hypoxia recovery period, the alanine aminotransferase/glutamate dehydrogenase cycle mobilizes this carbon from alanine store. pyruvate produced by the reverse reaction of alanine aminotransferase is funneled to the tca cycle, while deaminating glutamate dehydrogenase regenerates, reducing equivalent (nadh) and -oxoglutarate to maintain the cycle function. keywords: alanine; alanine aminotransferase (alaat); glutamate; glutamate dehydrogenase (gdh); glycolysis; hypoxia; nitrogen . introduction the absence of a tissue or a system dedicated to oxygen uptake and delivery to the organs in plants may create localized hypoxic environments when oxygen diffusion is hindered by the anatomy and the structure of the tissue—e.g., dense cell packing. developing and germinating seeds, tubers, bulky fruits, meristems, germinating pollen, and the phloem are the organs the most likely to lack oxygen even when the whole plant is growing in aerobic conditions [ ]. environmental conditions like flooding or soil waterlogging are the other major causes of more or less prolonged periods of hypoxia/anoxia due to the slow diffusion of oxygen in water and competition of the roots with respiring microorganisms. in the context of climatic change, arable farmland productivity is threatened by more frequent heavy precipitation causing submergence and waterlogging of plants; furthermore, plants , , ; doi: . /plants www.mdpi.com/journal/plants http://www.mdpi.com/journal/plants http://www.mdpi.com http://www.mdpi.com/journal/plants plants , , of the fact that cultivated crops were not selected to cope with oxygen limitation is an aggravating condition [ – ]. consequently, like the adaptation of plants to drought and saline stress, low oxygen stress deserves more interest from the scientific community. low oxygen sensing, signaling, and adaptation of plants to its limitation at both the cellular and whole plant levels should be investigated more thoroughly, and the derived knowledge should be taken into account in breeding programs and agronomical practices for saving plant fitness, growth, and development even when oxygen availability is low [ ]. in the present article, we will first give an overview of the recent knowledge on low oxygen sensing and signaling in plants and adaptation by metabolic adjustment to submergence- or waterlogging-induced hypoxia/anoxia. secondly, we will focus on the major changes pertaining to the reconfiguration of amino acids metabolism, highlighting the role of alanine that accumulates during periods of stress as a c and n storage compound readily utilizable during the post-hypoxia recovery period. . the role of metabolic adjustment in cellular response to low oxygen availability hypoxia-induced inhibition of mitochondrial oxidative phosphorylation results in an energy crisis due to the insufficient atp production to face the energy requirement of cellular processes [ ]. microarray-based transcriptome analyses of organisms representing the four kingdoms of plants, animals (including homo sapiens), fungi, and bacteria submitted to varying degrees of oxygen deficiency showed that metabolic changes in relation to energy production (fermentation) and utilization are among the conserved responses across the four kingdoms [ ]. the nature of these changes suggests that they are aimed at counteracting the damaging effects of energy crisis. in arabidopsis, translatome analysis revealed a group of genes—actually named the core-hypoxia-responsive genes—which are prioritized for translation in response to low oxygen stress. several enzymes associated with the reconfiguration of carbon metabolism are members of this group—e.g., pyruvate decarboxylase (pdc and pdc ), alcohol dehydrogenase (adh ), and sucrose synthase (sus ) [ ]. analysis of the transcriptome of rice coleoptile, in a variety adapted to elongate under anoxia, showed (similarly to arabidopsis) the induction of the above mentioned genes, and very interestingly it showed that genes encoding enzymes of pyruvate and phosphoenolpyruvate (pep) metabolism are those that are the most affected [ ]. the transcription of genes encoding pyruvate phosphate dikinase (ppdk) and pep carboxykinase (pck) were strongly increased, and the gene encoding pep carboxylase (pepc) was strongly inhibited, while the expressions of genes encoding pyruvate kinase (pk) and pyruvate dehydrogenase (pdh) were hardly changed [ ]. in total, activation of the alcoholic fermentation pathway allows for nad+ regeneration to maintain glycolysis and atp production [ – ], and for saving atp, ppi-dependent enzymes are preferred to atp-dependent enzymes. this strategy is illustrated by the fact that sus is preferred to invertase, ppi-dependent phosphofructokinase (pfp) is preferred to phosphofructokinase (pfk) for f- - -bis-p synthesis and ppdk is preferred to pyruvate kinase (pk) for pyruvate synthesis [ , ]. induction and coordination of the expression of low oxygen stress-responsive genes—including those involved in primary metabolism and energy homeostasis under hypoxic and anaerobic conditions—were shown to be under the control of transcription factors belonging to the group-vii ethylene response factors (erfs) rap . , rap . , rap . , hre , and hre ; for review, see [ , , ]. recently, rap . and rap . were shown to act redundantly as principal activators of low oxygen stress-inducible genes and rap . contributes to this redundancy [ ]. the group vii erfs involved in low oxygen stress are subjected to oxygen-dependent posttranslational modification through the n-end rule pathway (nerp) for protein destabilization [ – ]. it is proposed that as cellular oxygen concentration decreases, rap . and rap . , which are constitutively expressed, would escape post-translational modification and proteolysis via the nerp before being transported to the nucleus where they stimulate the expression of secondary erfs such as hre and hre , allowing then for several down-stream hypoxia-response genes to be expressed [ , ]. upon the return to normoxia, all the members of the group vii erfs are subjected to the nerp-mediated degradation. plants , , of arabidopsis double mutant affected in both arginyl-trna transferase and (ate /ate ) and the mutant affected in n-recognin proteolysis (prt ) unable to run nerp-mediated protein degradation exhibited constitutive expression of marker genes of hypoxic and anaerobic metabolism (adh, pdc, sus) as well as more than half of the core hypoxia-induced genes [ ]. it has been shown that if overexpression of the native rap . improves survival under low oxygen stress, the constitutive accumulation of versions of rap . insensitive to nerp proteolysis decreased survival, indicating that a fine-tuning of transcription is a prerequisite for cellular homeostasis under hypoxia. interestingly, it has been recently demonstrated in arabidopsis that rap . is negatively regulated through a protein–protein interaction with a hypoxia-inducible transcription factor that encodes a trihelix dna-binding protein named hypoxia response attenuator (hra ). in addition to its negative regulation of rap . , hra negatively regulates activation of its own promoter. finally, it is worth noting that hra is transcriptionally activated by rap . upon stabilization. it appears then that hra and rap . constitute a control unit that allows plants to modulate the extent of the response to hypoxia, including anaerobic enzyme production to levels that improve low oxygen stress endurance [ ]. the cross kingdom comparison of transcriptomic adjustment to low oxygen stress highlighted plant-specific responses; in plants, ethanol rather than lactate fermentation regenerates nad+. this regeneration is crucial to maintain higher rates of glycolysis. efficiency of this strategy for atp production is very low, it is carbohydrate-costly and it drains the carbon store of the cell very quickly, leading to carbon starvation and cellular death. therefore, it appears that management of carbon reserves is crucial for survival upon hypoxia [ ]. this explains why the ability to supply the roots with carbohydrates—the substrate of alcohol fermentation during prolonged periods of soil hypoxia/anoxia—appeared as a determinant in waterlogging tolerance, as well illustrated in the case of common ash (fraxinus excelsior) [ ]. similarly, hypoxia/anoxia-sensitive seeds of wheat and barley do not induce amylases under hypoxic/anoxic conditions of germination, in contrast to anaerobic germination-competent rice seeds [ ]. another specificity of the plants is the reconfiguration of nitrogen metabolism, in particular amino acids metabolism via alanine fermentative pathway [ , , ]. . alanine aminotransferase safeguard carbon in a nitrogen store upon hypoxia alanine fermentative pathway does not regenerate nad+, and unlike several metabolites known for either their signaling or protective role upon abiotic stresses—e.g., proline, betaine; alanine intrinsically may not play a protective role in hypoxic stress [ , , ]. nevertheless, alanine was shown to accumulate in various plant species under hypoxia/anoxia conditions. furthermore, in arabidopsis plantlets submitted for h to anoxic atmosphere ( . % argon) alaat (alanine aminotransferase; at g ) was the only nitrogen metabolism gene among the core hypoxia-responsive genes [ ]. alaat expression was induced in arabidopsis under similar or even less-drastic oxygen stress—e.g., in hairy roots soaked in hypoxic ( . % o ) liquid medium [ ], in young seedlings soaked in hypoxic ( % o ) [ ] or anoxic ( % n % h ) [ ] liquid medium, and in plantlets grown on solid medium under anoxic ( . % argon), or hypoxic ( % or . % o ) atmosphere [ , ]. in legume species medicago truncatula, lotus japonicas, and glycine max, either alaat activity, gene expression, or both were shown to increase in the roots of waterlogged plants [ – , ]. insight on the regulation of the expression of alaat under low oxygen stress was gained by browsing public transcriptomic data of arabidopsis mutants affected in the expression of genes encoding members of the group vii erfs transcription factors and genes encoding enzymes necessary for nerp-mediated degradation of proteins [ ]. from this investigation, it appeared that, similarly to hypoxia marker genes adh (at g ) and pdc (at g ), the expression of alaat (at g ) was affected in mutants either overexpressing rap . or knocked out in its expression [ ]. compared to the wild-type, the expression of alaat was strongly increased in the shoots of the rap . overexpressors, but only under hypoxia in the dark and not under hypoxia in the light or normoxia in the dark [ ]. plants , , of unlike the above-mentioned hypoxia marker genes, both alaat genes (at g and at g ) were not up-regulated under non-stress conditions in the mutants defective in nerp-mediated degradation of proteins (ate /ate and prt ) under normoxia or hypoxia ( h) [ ]. finally, unlike several hypoxia-regulated genes, alaat was not over-induced by flooding in arabidopsis mutants overexpressing rap . [ ]. altogether, these data show that rap . is necessary but not sufficient for hypoxia-induced alaat in the shoots of arabidopsis. a yet-unknown dark stress-dependent element seems to be necessary in conjunction with rap . for the induction of alaat by hypoxia (see hypothetical cross-talk between hypoxia- and darkness-induced signaling pathways for transcriptional regulation of alaat in [ ]). these data also suggest that alaat regulation might not be dependent on nerp for oxygen sensing in plants. reconfiguration of primary c/n metabolism upon hypoxia was investigated in vivo in medicago truncatula, lotus japonicas, and glycine max through experiments using n and c isotope labeling and metabolomics approach [ , , ]. altogether, these studies allow the conclusion that the reversible reaction of the interconversion of pyruvate and glutamate to alanine and -oxoglutarate is the main route of alanine synthesis under hypoxia (figure ). gaba transaminase (gaba-t) that can use either pyruvate or -oxoglutarate as amino acceptor seems to preferentially use pyruvate under hypoxic conditions, which constitutes an alternative pathway for alanine accumulation. however, arabidopsis gaba-t null mutants accumulated only slightly less alanine than wild-type upon hypoxia [ , ]. alaat activity was investigated in vivo by feeding medicago truncatula seedlings with either n-glutamate or n-alanine; upon hypoxia, alaat activity was directed towards alanine synthesis using glutamate as amino donor, while the reverse reaction of glutamate synthesis using alanine as amino donor was inhibited [ ]. labeling medicago truncatula [ ] and glycine max [ ] with nh + showed that after h, alanine accumulated as the major labelled amino acid in hypoxic tissues. interestingly, n-glutamine, n-asparagine, and n-aspartate were dramatically low, while n-glutamate was synthesized at levels close to that in the control with the pool of n-glutamate remaining stable. nh and c-glutamate labeling data in glycine max showed that under hypoxia, the label accumulated in alanine, glutamate, and -oxoglutarate at higher concentrations than that in the control, while the opposite was true for glutamine. in the same study, n-gaba was significantly higher than in the control, and c-glutamate labelling revealed considerable gaba shunt activity that explained the increase in the redistribution of c to succinate [ ]. altogether, these results suggest that rather than just an activation of alanine synthesis, amino acids metabolism is deeply affected by oxygen limitation and energy shortage. limami et al. [ ] suggested that the major reconfiguration of amino acids metabolism under hypoxia consisted of a concerted modulation of nitrogen flux through the pathways of both alanine and glutamate synthesis. the atp-consuming enzymes glutamine synthetase (gs) and asparagine synthetase (as) were significantly inhibited—probably as part of a cellular strategy to mitigate the damaging effect of energy crisis. regeneration of glutamate as a substrate of alaat and glutamate decarboxylase (gdc) is likely to occur through the reductive amination of -oxoglutarate by glutamine oxoglutarate amino transferase (gogat). through a c-pyruvate feeding experiment in soybean, it was proposed that nadh-gogat uses glutamine along with c-oxoglutarate to synthesize a mixture of c-glutamate and c-glutamate [ ]. in medicago truncatula, the inhibition of gogat with azaserine disturbed alanine accumulation and blocked germination and seedling establishment under hypoxia/anoxia [ ]. in total, it appears that changes in amino acids metabolism may contribute in several manners to mitigate damaging consequences of oxygen limitation. upon hypoxic stress, in roots, nadh-gogat activity contributes to the regeneration of nad+ that helps glycolysis to proceed [ ]. through alanine shunt, synthesis of alanine generates -oxoglutarate, which can be further metabolized to succinate via the tca cycle enzyme succinate coa ligase, thus providing additional atp per molecule of sucrose metabolized [ ]. alanine synthesis saves carbon by competing with ethanol synthesis for the common precursor pyruvate. ethanol is a dead-end product that leaks out of the tissue, representing a net loss of carbon [ , ]. storing nitrogen in the form of alanine through the nadh-gogat/alaat cycle plants , , of saves atp that is otherwise necessary for assimilating mineral nitrogen as glutamine and asparagine via atp consuming enzymes (figure ). plants , , of figure . schematic representation of the central role of alanine during hypoxia and post-hypoxia recovery periods. hypoxia: visualization of carbon flux from carbon storage compounds to alanine through alaat/nadh-gogat cycle. (post-hypoxia) visualization of alanine mobilization through alaat/gdh cycle and carbon flux towards tca cycle. scheme drawn by integrating data from transcriptomic and metabolomic studies and studies combining n and c labeling in various species such as medicago truncatula, lotus japonicus, glycine max and arabidopsis thaliana. alaat: alanine aminotransferase; gdh: glutamate dehydrogenase gogat: glutamne oxoglutarate aminotransferase. . alanine aminotransferase/glutamate dehydrogenase cycle mobilizes carbon from the nitrogen store upon reoxygenation in plants, gdh was shown to operate mainly in the direction of glutamate deamination to provide carbon skeletons and reducing equivalents [ – ]. in arabidopsis, gdh gene expression and enzyme deaminating activity were boosted by the exposure of plants to several days of darkness that lead to severe carbon shortage [ , – ]. in gdh - - arabidopsis triple mutants deprived of gdh activity, alanine and gaba accumulated in the roots where gaba shunt was activated to compensate for the lack of nadh-gdh as a provider of carbon to the tca cycle [ ]. involvement of gdh in low oxygen stress received little attention compared to that in other abiotic stresses. still, browsing public transcriptomic data of arabidopsis submitted to various conditions of low oxygen stress showed that the expression of glutamate dehydrogenase isogene gdh (at g ) and gdh (at g ) was affected; gdh expression increased after min of exposure to hypoxia ( . % o ) [ ], gdh and gdh were up-regulated by h of anoxia (atmosphere of % n ) [ ] and gdh and gdh [ ] were up-regulated by h of anoxia ( % n , % h ) in darkness. all these experiments were run on media supplemented with sucrose, a condition that rules out an induction of gdh genes expression only as a consequence of hypoxia/anoxia-induced carbon shortage. in medicago truncatula submitted to waterlogging-induced hypoxia, the expression of gdh (medtr g ) was strongly up-regulated similarly to that of the mitochondrial alaat (medtr g ) [ ]. the question of whether gdh would exceptionally, under low oxygen stress, operate in the direction of glutamate synthesis (and by doing so participate to the regeneration of nad+) was addressed in medicago truncatula. feeding the seedlings nh + in the presence and absence of the gs-inhibitor methionine sulfoximine (msx) under hypoxic condition showed clearly that gdh activity was very low compared to normoxic condition and was not contributing to glutamate synthesis [ ]. the discrepancy between gdh gene expression and enzyme activity suggests that the induction of the gene encoding gdh upon hypoxia may be interpreted as figure . schematic representation of the central role of alanine during hypoxia and post-hypoxia recovery periods. hypoxia: visualization of carbon flux from carbon storage compounds to alanine through alaat/nadh-gogat cycle. (post-hypoxia) visualization of alanine mobilization through alaat/gdh cycle and carbon flux towards tca cycle. scheme drawn by integrating data from transcriptomic and metabolomic studies and studies combining n and c labeling in various species such as medicago truncatula, lotus japonicus, glycine max and arabidopsis thaliana. alaat: alanine aminotransferase; gdh: glutamate dehydrogenase gogat: glutamne oxoglutarate aminotransferase. . alanine aminotransferase/glutamate dehydrogenase cycle mobilizes carbon from the nitrogen store upon reoxygenation in plants, gdh was shown to operate mainly in the direction of glutamate deamination to provide carbon skeletons and reducing equivalents [ – ]. in arabidopsis, gdh gene expression and enzyme deaminating activity were boosted by the exposure of plants to several days of darkness that lead to severe carbon shortage [ , – ]. in gdh - - arabidopsis triple mutants deprived of gdh activity, alanine and gaba accumulated in the roots where gaba shunt was activated to compensate for the lack of nadh-gdh as a provider of carbon to the tca cycle [ ]. involvement of gdh in low oxygen stress received little attention compared to that in other abiotic stresses. still, browsing public transcriptomic data of arabidopsis submitted to various conditions of low oxygen stress showed that the expression of glutamate dehydrogenase isogene gdh (at g ) and gdh (at g ) was affected; gdh expression increased after min of exposure to hypoxia ( . % o ) [ ], gdh and gdh were up-regulated by h of anoxia (atmosphere of % n ) [ ] and gdh and gdh [ ] were up-regulated by h of anoxia ( % n , % h ) in darkness. all these experiments were run on media supplemented with sucrose, a condition that rules out an induction of gdh genes expression only as a consequence of hypoxia/anoxia-induced carbon shortage. in medicago truncatula submitted to waterlogging-induced hypoxia, the expression of gdh (medtr g ) was strongly up-regulated similarly to that of the mitochondrial alaat (medtr g ) [ ]. the question of whether gdh would exceptionally, under low oxygen stress, operate in the direction of glutamate synthesis (and by doing so participate to the regeneration plants , , of of nad+) was addressed in medicago truncatula. feeding the seedlings nh + in the presence and absence of the gs-inhibitor methionine sulfoximine (msx) under hypoxic condition showed clearly that gdh activity was very low compared to normoxic condition and was not contributing to glutamate synthesis [ ]. the discrepancy between gdh gene expression and enzyme activity suggests that the induction of the gene encoding gdh upon hypoxia may be interpreted as anticipation of the return to aerobic conditions. it has been observed that the return to aerobic conditions was anticipated in plants subjected to hypoxic stress by expressing genes whose products have functions during the subsequent recovery period [ ]. in this case, gdh’s main role would be the regeneration of -oxoglutarate by deaminating glutamate during the post-stress recovery period (figure ) [ ]. this role of gdh during reoxygenation is further supported by the observation in arabidopsis that gdh and gdh were induced to much higher levels during reoxygenation than during anoxia. in addition, a third isogene gdh that was not affected by low oxygen stress was up-regulated specifically during reoxygenation [ ]. interestingly, in this study, atalaat and atalaat were also re-induced during reoxyganation [ ]. the hypoxia-inducible isognene alaat in arabidopsis showed a similar pattern of regulation and activity [ ]. expression of the gene encoding alaat was up-regulated by hypoxic stress, while the activity of the enzyme was shown to be the conversion of alanine into pyruvate and glutamate during the post-hypoxic period. finally, a non-plant model—that is, gdh from the tail muscle of the freshwater crayfish orconectes virilis—supports the idea of the involvement of gdh during the return to normoxia. in this animal it was shown that gdh is submitted to a posttranslational regulation—phosphorylation of the enzyme inhibits its activity under oxygen limitation until the return to normoxia [ ]. . conclusions altogether, these results allow the suggestion of a model of storage and mobilization of carbon during the transition from hypoxia to post-hypoxia stress (figure ). during hypoxia stress, pyruvate as a byproduct of glycolysis is competitively used through an alaat/nadh-gogat cycle, leading to the storage of carbon in alanine. alanine is synthesized by alaat using glutamate as an amino donor, while nadh-gogat uses -oxoglutarate to regenerate glutamate and nad+. during the post-hypoxia recovery period, carbon is mobilized through an alaat/gdh cycle. alanine is deaminated by the reverse reaction of alaat to produce pyruvate and glutamate. carbon is funneled to the tca cycle as pyruvate, while gdh, by deaminating glutamate, generates -oxoglutarate to maintain the cycle function and produce reducing equivalent (nadh). conflicts of interest: the authors declare no conflict of interest. references . van dongen, j.t.; 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[crossref] [pubmed] © by the authors; licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc-by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . /jxb/erm http://www.ncbi.nlm.nih.gov/pubmed/ http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /pce. http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /s - - - http://www.ncbi.nlm.nih.gov/pubmed/ http://creativecommons.org/ http://creativecommons.org/licenses/by/ . / 	introduction 	the role of metabolic adjustment in cellular response to low oxygen availability 	alanine aminotransferase safeguard carbon in a nitrogen store upon hypoxia 	alanine aminotransferase/glutamate dehydrogenase cycle mobilizes carbon from the nitrogen store upon reoxygenation 	conclusions energy shocks, crises and the policy process: a review of theory and application butler university from the selectedworks of peter z. grossman energy shocks, crises and the policy process: a review of theory and application peter z. grossman, butler university available at: https://works.bepress.com/peter_grossman/ / http://www.butler.edu https://works.bepress.com/peter_grossman/ https://works.bepress.com/peter_grossman/ / review article energy shocks, crises and the policy process: a review of theory and application peter z. grossman butler university, college of business, sunset avenue, indianapolis, in , usa h i g h l i g h t s � an analysis of the idea of “crisis” and its application to energy. � a review of theories and models of the policy process and of policy change. � theory applied to two energy cases. � suggestion as to how the analysis of energy policymaking might be approached in the future. a r t i c l e i n f o article history: received may received in revised form november accepted november keywords: energy policy energy crisis policy theory a b s t r a c t what motivates changes in energy policy? typically, the process begins with a notable exogenous event, a shock. often, the shock leads to what is perceived to be a crisis. this review essay surveys theories of crisis policymaking from the social science literature and considers their application to changes in energy policy. two cases—one from the u.s., the other from germany—are examined in more detail from the standpoint of the theories discussed. suggestions are made for improving energy policy analysis in the future. & elsevier ltd. all rights reserved. contents . introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . what is a “crisis”? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . theories and models of crisis policymaking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . from incrementalism to speculative augmentation and the issue-attention cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . public satisfying-speculative augmentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . the issue-attention cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . three post-incrementalist theories of the policy process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . multiple streams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . punctuated equilibrium. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . advocacy coalition framework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . energy-crisis models of policy change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ambivalent majoritarian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . the “do something” dilemma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . economic crisis policy models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . rational choice with ignorance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . crisis opportunism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . models and theories of the policy process: what do they explain? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . contents lists available at sciencedirect journal homepage: www.elsevier.com/locate/enpol energy policy http://dx.doi.org/ . /j.enpol. . . - /& elsevier ltd. all rights reserved. e-mail address: pgrossma@butler.edu energy policy ( ) – www.sciencedirect.com/science/journal/ www.elsevier.com/locate/enpol http://dx.doi.org/ . /j.enpol. . . http://dx.doi.org/ . /j.enpol. . . http://dx.doi.org/ . /j.enpol. . . http://crossmark.crossref.org/dialog/?doi= . /j.enpol. . . &domain=pdf http://crossmark.crossref.org/dialog/?doi= . /j.enpol. . . &domain=pdf http://crossmark.crossref.org/dialog/?doi= . /j.enpol. . . &domain=pdf mailto:pgrossma@butler.edu http://dx.doi.org/ . /j.enpol. . . . energy crisis policymaking: two cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . the comprehensive energy policy act of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . energiewende . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . introduction it has been casually observed that in the united states “pro- gress on energy policy” requires a crisis (dunn, ). this is ap- parently understood among policymakers and the observation does, at least in one sense, fit the facts. virtually all major u.s. energy legislation has passed during, or in the aftermath of, what has been widely perceived to be an energy crisis. in addition to new legislation, the atmosphere of crisis may also produce chan- ges in the bureaucracy, the renewal and expansion of existing programs, or the realignment of advocacy groups both in, and outside of, government. absent the perception of crisis, energy policy is typically stymied by competing interest groups and consequently any effort at significant policy change quickly loses momentum. whether any of america's energy legislation or other policy changes represents “progress” is another matter. as described in grossman ( ), for the most part, such legislation has embodied more the sense of government panic than a move toward effective energy policies. keeler ( , ) has suggested that this is a likely outcome because, “a crisis can create a sense of urgency… [that] allows for unusually rapid acceptance of reform proposals intended to resolve the crisis.” even president jimmy carter once noted that crises lead predictably to “ever more massive govern- ment bureaucracy and regulations, and ill-considered last-minute, crash programs,” a cogent analysis, which he subsequently ignored. still, the connection between “energy crises” and ensuing changes in energy policy is very real especially in in the american political context. this paper surveys theories and models of crisis policymaking in the social science literature and explores how well they illuminate the process and outcomes of energy policy efforts. i have referred to “energy crises” often with the qualifier “perceived” because before any discussion of the theory of crisis policymaking, it is important to develop a clear understanding of just what is meant by a “crisis,” and especially an energy crisis. claims that america (or even the whole world) has faced an en- ergy crisis have been ubiquitous for the past forty years. between and , in the u.s. congress alone, the term was used about times in debates and speeches. so large a number of utterances suggest both its ready acceptance as a catch-phrase and that its meaning is ambiguous. scholarly literatures give various definitions of “crisis” gen- erally (e.g. keeler, ; boin et al., ; coyne, ) and there have been efforts to define “energy crisis” as a distinct sub- category. but based on these it is questionable that any event should have been called an energy crisis (garrison, ; gross- man, ). of course, if that is the case, it would seem that policy has been motivated only by the perception of a crisis. of course, even imagined crises do not occur in a vacuum. there are typically one or more precipitating events, “shocks,” that lead to the ensuing “crises.” shocks may be sudden and dramatic socioeconomic surprises, or they may start as mere glitches that mushroom into conditions that take on societal importance and entail potential economic and, more importantly from the pol- icymaker's perspective, political costs if left alone. it is fair to say that energy shocks have occurred although these have often been the result of poor policies not exogenous events in energy markets. but it is important to distinguish an initial shock—e.g. a sudden oil price spike—from any larger sense of crisis that might follow. this essay is organized as follows: the next section explores the definition of crisis as it appears in the scholarly literature as well as in common parlance. there are also specific definitions of an “energy crisis.” these definitions are much less demanding in terms of how strongly events impact a society. indeed, it will be argued that the social science definitions of societal crises are too strong to apply to most energy problems. section examines the theories and models of policy change, specifically as to the ways in which shocks and crises are thought to impact the policymaking process. in general, a shock brings public attention to an issue, and if the impacts are acute and/or persistent the situation may be deemed a crisis. the crisis mindset may push energy to the top of policymakers' agenda, and lead to policy change, sometimes major change. the models and theories attempt to explain why the process of crisis policymaking may lead at time to significant policy changes, but at other times, to no changes, incremental change or changes that prove to be short- lived. section considers how well the literature of crisis policy- making explains what is subsequently observed with respect to energy policy. two cases of policy activity in response to perceived crises are briefly explored. the first is from the united states—the period in the early s in the aftermath of the first gulf war; the second is from germany and examines the shocks and crises that led to germany's dramatic policy of “energiewende,” the “energy transition.” a discussion of what has been learned and how future analyses might be structured concludes. . what is a “crisis”? what is meant by calling any event a crisis? garrison ( , ) paraphrases one dictionary definition as “an acute turning point usually involving some disruption or dis- order,” a definition not far from one that scholars have used. coyne ( ), for example, defines a crisis as “an unexpected event that creates uncertainty and poses a direct or perceived threat to the goals and norms of an organization or society.” to boin and thart ( , ) it is a “grave predicament requiring urgent action.” boin et al. ( , ) term “a crisis…a phase of disorder in the seemingly normal development of a system…[c]rises are jimmy carter speech to the nation, nov. , . congressional record, th– th congress. http://thomas.loc.gov/home/ legislativedata.php?&n¼record&c¼ . e.g. the california electricity crisis ( – ) was caused largely by a very poorly designed electric power restructuring bill passed in (duane, ; grossman, ). p.z. grossman / energy policy ( ) – http://thomas.loc.gov/home/legislativedata.php?&n=record&c= http://thomas.loc.gov/home/legislativedata.php?&n=record&c= http://thomas.loc.gov/home/legislativedata.php?&n=record&c= http://thomas.loc.gov/home/legislativedata.php?&n=record&c= http://thomas.loc.gov/home/legislativedata.php?&n=record&c= http://thomas.loc.gov/home/legislativedata.php?&n=record&c= http://thomas.loc.gov/home/legislativedata.php?&n=record&c= http://thomas.loc.gov/home/legislativedata.php?&n=record&c= http://thomas.loc.gov/home/legislativedata.php?&n=record&c= http://thomas.loc.gov/home/legislativedata.php?&n=record&c= transitional phases, during which the normal ways of operating no longer work.” a marxian perspective (offe, , ) describes a crisis as “processes in which the structure of a system is called into question;” nohrstedt and weible ( , ) argue that, “crises de- note periods of disorder…along with widespread questioning or discrediting of established policies, practices and institutions.” according to congleton ( ), a crisis has three character- istics: surprise, unpleasantness and urgency. urgency, the experi- ence of unpleasantness in an immediate, pressing fashion, is cru- cial for boin et al. ( ) as well. they argue that the components of a crisis are a “threat” as well as uncertainty and urgency. be- cause of a sense of urgency there is “time compression,” the ap- prehension that the “threat is here, it is real, and it must be dealt with as soon as possible…” but because there is “a high degree of uncertainty…both to the nature and potential consequences of the threat,” (boin et al., , ) crises may also lead to a feeling of helplessness (“what's next?” and “what can we do?”), as well as a tendency to policy recklessness. eyestone ( , , emphasis in the original), for example, argues that “some actions taken in the midst of crisis probably should not have been taken, and would not have been taken except for the urgency of the moment.” ahrari ( ), writing about the synfuels legislation in the u.s., suggests such radical policy changes, might, in hindsight, be con- sidered “irrational.” urgency does not necessarily mean that all crises are experi- enced acutely, or as threatening episodes that come as a total surprise to society. there are, for example, protracted crises or “creeping” crises that “take some time to develop…[and] involve an accumulation of adverse conditions” (rosenthal and kouzmin, , ). still, these accumulations only become a crisis when they engender a feeling of emergency that must be addressed. how much the sense of urgency matters with respect to crisis policymaking can be seen in connection to the issue of climate change. in the u.s., urgency has been largely missing (obviously not among experts and advocates, but with the general public ). therefore no immediate action has been required, and little policy action, at the national level, has been undertaken. while this has been true for the u.s. and many other countries, the german public did embrace climate change as a crisis (brechin, ); this per- ception has persisted spurring radical policy changes. a society-wide crisis (such as, at least in theory, a crisis related to energy) according to keeler's ( , ) definition, is “a si- tuation of large-scale public dissatisfaction or even fear stemming from wide ranging economic problems and/or an unusual degree of social unrest and/or threats to national security.” yet “it is often unclear which events should actually qualify as a crisis” (nohr- stedt, , ). this, i would argue, is especially true of events called “energy crises” in the s, energy market disruptions were said to be a “threat to the goals and norms of an organization or society” (coyne, ), but experience showed soon afterwards that they were not—even though the claim of “crisis” resurfaced frequently for the next four decades. some of the consequences of the oil embargo, especially the lines at gasoline pumps, were both unanticipated and disagreeable, but the embargo itself was foreseeable; akins ( ) had written of the possibility in the spring of . nevertheless, since , well into the s in fact, polls have shown that americans generally have expected that (a) there would be additional energy crises and (b) these would have the same kinds of effects as those experienced in – . in retrospect, however, the one genuine surprise to americans in quickly became accepted wisdom. that was, that the u.s. had become part of a world oil market and thus prices would be more volatile and out of the control of u.s. officials thereafter. but the main focus of public attention in every perceived en- ergy crisis in the u.s. has been on the specific hardships the crisis seemed to be causing. this has affected definitions of energy cri- ses, which tend to emphasize effects or a couple of simplifying issues. common definitions, for example, center on the visible and discomforting problems disruptions in energy markets cause. a web site offers the following: “an energy crisis is a society-wide economic problem caused by a constricted supply of energy leading to diminished availability and increased price to consumers.” other definitions (e.g. wikipedia) refer to supply “bottlenecks.” this perception tallies with experience of what have been called energy crises. but a supply bottleneck hardly seems a “grave predicament requiring urgent action.” in reality, energy crises in the u.s. have imposed costs and raised general economic concerns, but they have not represented genuine threats to na- tional security, or the norms of society—as is encompassed in most scholarly definitions of “crisis.” of course, the rhetoric surrounding energy crises has empha- sized extreme outcomes. whatever the actual danger to society, in the midst of crises, policymakers, the media, and even parts of the energy industry have prophesized dire consequences if some sort of major policy action was not undertaken. in the s the crisis was said to be both increasing dependence on other nations for oil, and rapidly dwindling domestic oil and natural gas supplies. pol- icymakers claimed the threat from this dependence imperiled the wealth, comfort and security of the u.s. if not the whole in- dustrialized world. in fact except for price volatility (which could possibly cause mild economic downturns), none of the fears were realistic. nevertheless, into the s, officials continued to assert that the u.s. was a “hostage” to organization of petroleum ex- porting countries. uncertainty is a component of a crisis, and especially so when the issues (such as those with energy) are technical, not easily explained and still less amenable to an obvious solution. officials have seldom grasped the underlying causes of diminished avail- ability or rising prices of energy supplies, nor have they compre- hended what to do to overcome them (grossman, ). thus it has been indeterminate (to policymakers as well as the public) whether any policy change would offer some relief to consumers or make matters worse. claims of benefits from proposals have been highly speculative, and often predicted effects have been at wide variance with one another. for example, year-round daylight savings time, imposed temporarily during the – arab oil embargo, was predicted to cut oil consumption by somewhere between , barrels (bbl.) and , bbl. per day, a vast range of uncertainty, that could only confuse the general public. forecasts of prices and reserves also were persistently and often enormously wrong, in the latter case provoking a belief that total exhaustion of energy resources was imminent (grossman, ). officials sought to deflect criticism of their lack of action by re- ferencing, and pledging to back, one or another panacea new technology that would solve energy problems once and for all. synthetic fuels corporation act of (public law – ; stat. et seq.). a gallup poll in early showed climate change far down on the list of issues crucial to the american public. survey respondents were far more worried about affordable energy. at: http://www.gallup.com/poll/ /climate-change- not-top-worry.aspx. the federal government has tried to address climate change through the environmental protection agency and state governments, especially california, have adopted programs to reduce carbon dioxide emissions. oil and gas price spikes are typically treated as energy market shocks. ha- milton ( , ) argues that “an oil shock occurs when oil prices exceed their -year peak,” a definition that has been used by other economists. econ .org. this is given as the “consensus” definition. rep. ed markey (d-ma), congressional record th congress. june , . p.z. grossman / energy policy ( ) – http://www.gallup.com/poll/ /climate-change-not-top-worry.aspx http://www.gallup.com/poll/ /climate-change-not-top-worry.aspx belief (both among officials and the general public) in the power of technology to resolve an energy crisis has been exceedingly naïve and unfulfilled (grossman, ). despite uncertainty, in the midst of an acute crisis, policy- makers often feel compelled to propose changes that may be quite radical. but there is an important aspect to energy crises that make them quite unlike such crises as wars or natural disasters. that is, energy markets, especially oil markets, have usually resolved cri- ses without any governmental intervention, much less radical change. this cannot be said of war or, say, a disaster like hurri- cane katrina—to which no strictly market solution is possible. even environmental crises generally demand a policy response, (including ones that involve energy such as power plant emissions or oil spills), although it may take the form of assigning property rights over environmental goods to allow for market-like solu- tions. but with energy, bottlenecks disappear unless existing po- licies prevent it; prices stabilize. policy changes often have started as radical proposals—made when a “crisis” was especially salient—but unless the sense of crisis has persisted, legislation is likely to become more incremental (lindblom, ), subject to the wishes of competing groups and leading to at most small changes at the margin. policymakers who have a vested interest in the distribution of energy-related benefits will also seek to prolong a crisis. that is, “the recognition of the potential utility of a crisis for the achievement of policy innovation is prevalent enough so that po- litical leaders have often attempted to create through rhetoric and related actions a public sense of crisis” (keeler, , ) what- ever the reality. when the sense of crisis is gone so is the chance for larger change—and the redistribution of benefits major policy shifts create. regardless of what an individual legislator may think the term “energy crisis” means, in actuality he or she is likely to state it as what zahariadis ( , ) terms a “higher order symbol.” ev- eryone knows what it means so it is self-explanatory, only it is not and often it is invoked with no clear explicit or implicit meaning, and no evident direction for policy. perhaps the best approach to the concept of energy crisis is suggested by garrison ( ). the term “energy crisis,” he argues, is a linguistic symbol, a metaphor. the – energy crisis only revealed the potential dangers of resource exhaustion and world market dependence, but in fact there was neither an end to oil nor the loss of national sovereignty nor any other dire societal consequence. thus calling it a crisis was not correct, he claims, in the sense that some dangerous turning point had been reached, but he avers that the “crisis” revealed that the turning point was now in view (although only hypothetically). keeler ( , ) argues, it is “only when a social problem is severe enough to make a public audience receptive to its depiction as a crisis can it be expected to have a significant impact on the policy-making pro- cess.” but following garrison it seems all that is needed is that the precipitating event (a shock) captures public attention and that any underlying problems can subsequently be depicted as severe— especially if some evident vestige of the shock persists. stone ( , ) points out that “our understanding of real situations is always mediated by ideas; those in turn are created, changed, and fought over in politics…political actors use narrative story lines and symbolic devices to manipulate so-called issue characteristics all the while making it seem as though they are simply describing facts.” whether or not the story leads to policy change may de- pend on “skillful exploitation” of the issue characteristics by those policy entrepreneurs and groups that would benefit from it (nohrstedt and weible, , ). along the same lines as garrison and stone, i have argued that “there is really no such thing as an energy crisis” (grossman, , – ), meaning some kind of tangible set of events that leads to an actual exhaustion or protracted unavailability of primary or sec- ondary energy supplies. of course there can be temporary dis- ruptions that are upsetting, but they have never represented a real threat to social order or national security. nevertheless, the words “energy crisis” do convey some idea and exist at least as a figure of speech as garrison ( ) argued more than years ago. what they convey is ambiguous—but then so many of the tropes of energy policy—e.g. energy independence, energy security—are also indistinct, subject to multiple interpretations, and reflecting varying belief systems so as to make much of energy discourse a clash of monologues. still, the belief in energy crises has catalyzed the policy process even when the result is no significant change in policy. indeed, only those crises not amenable to market solutions, such as ones with significant externalities, are likely to benefit from a policy response. . theories and models of crisis policymaking from the mid- s through at least into the s, the dominant theory of the policy process was incrementalism asso- ciated primarily with lindblom ( , ) (dahl and lindblom, ; braybrooke and lindblom, ). this theory posited that policy moved in small discrete steps. “a policy is directed at a problem; it is tried, altered, tried in altered form, altered again and so on” (lindblom, , ). there are, in this view, “continual policy readjustments in pursuit of marginally refined policy goals” (schulman, , ). one characteristic of incrementalism is that policies tend to be aggregations of the views of various or- ganizations and ideologies and the resultant policy “the sum total of countless individual interests” (schulman, ) whose parti- sans engage in an ongoing process of strategic analysis and mutual adjustment (lindblom and woodhouse, ). the goal is to build majority coalitions for incremental change that will capture some benefits for each of their various constituencies. lindblom of course recognized that crises leading to major policy changes oc- curred. he referred to them as “low understanding-large change” circumstances but he argued that “one would be hard put to for- malize the methods appropriate” to analyze them (braybrooke and lindblom, , ). instead, he focused on what many called (and some would call today) the “normal” policymaking process. because incrementalism did not easily accommodate crises or the policies that emerged from them, the advent of what were regarded as environmental crises in the late s and early s, called at a minimum, for “additional analytical” constructs (schulman, , , emphasis in the original) that could ac- count for “phenomena that lay outside” of prevailing theory and that elicited non-incremental policy responses. alternatively, cri- ses suggested the need for a different type of theory altogether. examples of both of these responses are presented in the accom- panying table . it should be noted that in the policy literature there are strong distinctions made between models and theories (ostrom, ; schlager, ). models are nested components of theories. that is, they “allow analysts to test specific parts of theories by fixing a limited number of variables at specific settings and exploring the outcomes produced” (schlager, , ). the first two columns of the table are roughly chronological and represent both additional analytics to incrementalism and financial crises may be one other kind of crisis that suggests market solu- tions, and in the nineteenth century financial panics, investment bubbles and other sorts of financial crises were allowed to run their course. in recent years, however, government interventions have been typical. the most significant changes in u.s. energy policy arguably have involved the repeal of prior rules, notably the end of oil and natural gas price controls (grossman, ). p.z. grossman / energy policy ( ) – new theory. that is, the models in the first column of table , both from the s, were seen as complements to basic incrementalist theory (the additional components lindblom felt “hard put” to provide) to afford some means to explain and/or test what hap- pens to the policy process in the event of a crisis. the theories in column (beginning in the s), on the other hand, were in- tended to revise considerably, if not replace, incrementalism as the central theory in analysis of the policy process. the third column lists models that have focused specifically on energy crisis policy outcomes in the context of policy theories noted in the first two columns. the first (ahrari, ), provides another addendum to incrementalism. the second (grossman, ), locates an energy policy model in the larger frame of various contemporary theories. the fourth column lists economic models that are pertinent to analysis crisis policymaking. economic theory has tended to ignore crises except for those connected to the business cycle, but the two models discussed here have more evident applicability to policy- making in the context of energy or environmental crises. . . from incrementalism to speculative augmentation and the is- sue-attention cycle “you never want a serious crisis to go to waste.”—rahm ema- nuel, chief of staff to barack obama ( – ) intuitively, a crisis would appear an ideal circumstance to in- itiate major policy changes. as rosenthal and kouzmin ( , ) note, “one's crisis may well be perceived as another's opportunity” because a crisis is “characterized by the necessity to make critical choices” often quickly before the possible costs and benefits are really understood, and when a cure-all program however im- plausible can sound especially attractive. according to eyestone ( , ), “normally cautious politicians suspend their re- sistance to untried approaches in view of the perceived necessity to respond promptly to the crisis.” during the energy market disruption that began with the fall of the shah of iran in december and persisted well into a carter administration official contended that members of congress were so desperate for solu- tions they would vote for anything that sounded like one even if it was “wrong” (cited in grossman, , ). of course, given prevailing uncertainty during a crisis, there is “an unusually high propensity for making policy errors” (congleton, , ). but with attention to the issue growing, ignoring it is not politically feasible (eyestone, ). with respect to energy policy in the u.s., in the face of a crisis, radical policy changes have always been proposed. but for the most part, they do not occur; more often than not, energy crises, politically, “go to waste.” even when more radical policies are adopted, the more drastic changes are likely to be partially or completely reversed when the sense of crisis has passed. still there are usually some features of the policymaking landscape that do change. the arab oil embargo did not lead to the kind of radical legislation president richard nixon or leading members of con- gress sought at the height of the crisis. but it did create a new narrative about energy and the role of policy (grossman, ), an energy bureaucracy that burgeoned in the years that followed (higgs, ), and a reordering of congressional committees as legislators attempted to claim a stake in energy policy (gulick, ). also, many and varied lobbying groups and policy en- trepreneurs appeared and sought whatever rents the national government was ready to appropriate. but if in fact radical policy change seldom transpires in the face of crises, why does it sometimes occur? what are the essential characteristics of the crisis-policymaking process, particularly as applied to the energy-crisis process? what are the conditions that support (or not) major policy change? . . . public satisfying-speculative augmentation as noted, environmental crises of late s had become major disruptive issues that that prompted a “dramatic surge in public concern” (jones, , ), and a demand for more decisive environmental policies. thus policymakers were unable to “merely stave off or nibble at [the issue]” (braybrooke and lind- blom, , ) as incrementalism suggested. these problems were, however, marked by “technical complexity,” such that the general public was lacking “knowledge of realistic alternatives (given scientific, technological, and economic realities)” (jones, , ) policymakers were reacting to public concerns but they did not understand the complexities either. jones ( ) therefore proposed a model of the policy process for these types of circumstances, a model he termed “public sa- tisfying-speculative augmentation.” in essence, in a crisis where there is both urgency and high complexity, policy proposals be- come stronger and stronger, as if each new idea is meant to display a greater concern than any previous proposal. in the early s, he found “active competition among elected officials [the pre- sident as well as congress] to produce and be credited with strong legislation” (jones, , ). feasibility mattered far less than exceeding the previous proposals. this process marked air quality legislation of the early s. president nixon suggested that ac- tion on air pollution had “virtual wartime urgency” and the bill that came out of committee was called in congress the “toughest air pollution clean-up bill ever.” proposed energy legislation underwent similar sorts of spec- ulative augmentation in the s. the oil embargo led to: calls for energy autarky, beginning with nixon's project independence, proposed in november ; demands for counter-embargoes of table evolution of theories of energy policy formulation since incrementalism. non-incrementalist crisis models: addenda to incrementalist policy theory post-incrementalist theories of the policy pro- cess (incorporating shocks and crises) energy crisis models of policy change economic crisis models public satisfying-speculative aug- mentation (jones, ) multiple streams (kingdon, ) ambivalent majoritarian (ahrari, ) rational choice with ignorance (congleton, ) issue-attention cycle (downs, ) punctuated equilibrium (baumgartner and jones, , ) the “do something” dilemma (gross- man, ) crisis opportunism (higgs, , ) advocacy coalition framework (sabatier, , ) ostrander and lowry ( ) note in general the “failure to change” that has marked u.s. energy policy adopted during or immediately after crises. this activity, according to oppenheimer ( , ) also provided “new ave- nues for legislative obstruction” of energy policy proposals. the period was marked by a number of shocks such as the oil spill off the coast of santa barbara, ca and the fire on the cuyahoga river, both of these events occurring in . quoted in the washington post see jones ( , p. ). p.z. grossman / energy policy ( ) – food; appeals for energy industry nationalizations; and proposals for other radical steps. democratic members of congress criticized project independence mainly on the basis of a claim that they had thought of it first and had advocated for more comprehensive measures and larger budgets to achieve it. at the same time, energy independence proposals demonstrate an important difference from environmental proposals. the clean air act of , one of the most consequential pollution control bills ever enacted, arguably came about as result of the process jones describes. but importantly, air pollution, was unlikely to improve on its own; pollution has a measurable concrete reality, while energy independence is an ambiguous abstraction with multiple meanings. of course, the gasoline lines and the escalating prices of energy in – were real enough, but those (as noted) ended through market forces. “public satisfying-speculative augmentation” as a model of crisis policymaking does help in appreciating the intense activity among policymakers when public opinion puts energy at the top of the agenda, but it does not for the most part explain the out- comes with respect to policy. that is, when does a crisis lead to dramatically altered policies, and when does it lead to nothing but policy rhetoric or to weak incrementalism? also, how likely is it that a major policy change initiated during a crisis will be effective? . . . the issue-attention cycle political scientist anthony downs ( ) proposed a cyclical crisis model that predated both jones's paper and the oil embargo, but addressed some issues that energy crises later raised. called the “issue-attention cycle,” downs's model had five stages: pre-crisis; “alarmed” discovery followed by “euphoric” en- thusiasm; discouraging realization of the costliness of solutions; decline of public interest in the issue; and finally a post-crisis fall off in attention. in the first stage, a problem exists but it has not caught the attention of the general public or of policymakers. thus, prior to the arab oil embargo there were experts who ex- pressed concern about the availability of domestic oil and gas supplies, but the issue was not near the top of the government's agenda nor did opinion polls find much concern about energy among the public generally. the gas lines and escalating prices following the embargo had a dramatic effect, raising an “alarmed” attention to energy. by the end of , the watergate scandal and rising inflation notwithstanding, almost half of the u.s. public believed energy the number one issue in the country. policy- makers—led by president nixon's plan for “energy independence” by —offered what could be called “euphoric” solutions ac- companied by images of america's technological history, notably the apollo moon landing, as an optimistic reminder that the u.s. had the know-how to solve any problem. or as downs ( , ) observes, “in the optimistic american tradition, [a] technological solution is initially assumed to be possible in the case of nearly every problem.” by the spring, reports surfaced that the cost of energy in- dependence would be on the order of hundreds of billions of dollars and it would succeed only if the policy was fortunate to experience (as one official said) the opposite of murphy's law— that everything that could go right did (grossman, , – ). meanwhile the gas lines and the embargo had ended and at- tention to energy waned as the watergate scandal took center stage. but in the post-crisis phase there were changes of a sort downs and other scholars argue would be likely. during the crisis and in the immediate aftermath, there was intensive organiza- tional activity and change with respect to energy within and outside of the government (jones and strahan, ). many groups had coalesced around the issue of energy and they were ready to act later in the decade when a second national energy crisis made energy the leading public concern. according to peters and hogwood ( ), the exact impacts on policy of the issue-attention model are vague. as they note ( ): “what is not fully clear from downs's explication of the stages of the cycle is how far he envisages that some form of policy and organizational response is launched by government to deal with the issue before interest fades away.” downs's model points to a conclusion that the crisis-policy process will wind down either when people realize “how difficult and how costly to themselves” (downs, , ) solutions will be or when the public just be- comes bored. in , although there were reports about cost, the policy process wound down not because of boredom but rather because of symptomatic relief; the most discomforting manifestations of the crisis had dissipated. polls, which had reflected the public's sense of urgency about energy in early , showed a marked decline in interest just months later. still it is uncertain whether downs thought of the “new institutions, programs and policies” that were “created to help solve” (downs, , ) the crisis re- presented significant shifts in policy or not. nevertheless there were some evident changes. as baumgartner and jones ( , ) observe in a discussion of the issue-attention model, when a crisis is salient, new programs and policies are likely to create “an in- stitutional legacy. institutions, especially government bureau- cracies, do not simply ‘fade away’ like public interest or media attention…” the issue-attention model appeared to argue that virtually all crisis legislation was fated ultimately to fail. it would promise too much, cost too much and would soon be largely forgotten. that has not been the story of some environmental legislation, but it does have resonance with u.s. energy policy. in – , there would there be another period of crisis, and this time major leg- islative initiatives would pass. but these major changes would be temporary, as it turned out, altering the policy landscape for a time, then lapsing into a downsian post-crisis phase of inattention from the public at large—until the inevitable next claim of an ex- tant “energy crisis.” but what both jones's and downs's papers made clear was this: incrementalism was not a very helpful theory with respect to is- sues prone to shocks and crises. subsequent theories of the policy process had to take the impact of such events into account. . . three post-incrementalist theories of the policy process downs and (more explicitly) jones constructed specific models of crises and public policy to fill what was perceived to be a gap in the prevailing, incrementalist theory of policymaking. but scholars also began to design general theories of the policy process that most people thought the latter had caused the former, but as is generally understood by economists today, u.s. oil price controls had been responsible for the gas lines, not the embargo (grossman, ). bernstein ( ) offered something of a precursor to downs's stages-type model, what he termed “the life cycle of regulatory commissions.” as in downs, regulatory bodies take on a life of their own and are unlikely to completely end “until some scandal or emergency calls attention to the failure of regulation…” (bernstein, , ). downs ( , ) writes: “[w]e should not underestimate the american public's capacity to become bored.” downs did recognize that major change was at least possible. if, for example, an issue such as a visible pollution problem could stay salient long enough, is viewed as threatening to a large segment of the population, has a relatively small group that can be pointed to as the “villains” (downs, , ), has a technological solution, and can be paid for without a general rise in taxes, then there may be the prospect of significant policies to address and possibly even solve it. p.z. grossman / energy policy ( ) – would incorporate shocks and crises as potential drivers of major or minor policy change. although there are many contemporary theories, three are particularly influential, often use similar ideas and tropes, and all highlight the impact of “exogenous socio-eco- nomic shocks” and crises on policymaking, often using as ex- amples energy and environmental issues at times of high salience. . . . multiple streams multiple streams (ms) theory borrows as a conceptual under- pinning the “garbage can” model of choice (cohen et al., ). in the garbage can are policymaking organizations (congress, the epa, etc.), conceived of as “organized anarchies” in which decision makers and their range of choices are fluid; ideas and people (with their varied preferences) drift in and out of the process with re- spect to any given problem, and no one individual or group con- trols the progression of choice. “[c]hoices looking for problems, issues and feelings looking for decision situations in which they might be aired” (cohen et al., , ) are the norm. policymaking occurs under a condition in which ambiguity is more evident than uncertainty. that is, there are different interests and interpreta- tions with respect to a given policy choice, and as more interests become involved the interpretations become more varied. as zahariadis ( , ) points out, more information may reduce uncertainty but it “does not reduce ambiguity.” indeed ambiguity increases as the individual interests, decision rules, preferences, past policy choices, and so on are added to the rest of the “garbage can.” motives and interests may be unclear not only to outsiders, but also to policymakers (conceived of as “boundedly” rational (simon, )) themselves. this is especially likely, it would seem, in the case where choices need to be made under time constraints —i.e. in a crisis. in the ms structure, there are essentially three “streams,” basic components of policymaking: problems, policies and politics that are typically jumbled together in the garbage can and yet also exist independently. problems exist outside the government although they may be generally salient only to one or another advocacy group; policies (that is, solutions) may be advanced by organiza- tions as well as policy entrepreneurs many of whom are more concerned about advancing their own interests rather than solving a prominent socio-economic issue; and politics is the larger frame of ideologies, elections and public opinion, in which policymaking takes place. yet shocks leading to crises may become what king- don ( ) calls “focusing events” that will “open a window” for policy entrepreneurs to “couple” the streams—link policy to a problem and to politics, and advance solutions that previously were lost in the garbage can. the result may be a major policy change (kingdon, ; john, ; zahariadis, ). kingdon ( , – ) argues that a single focusing event—he uses the oil embargo—might not in itself be sufficient to couple the streams and “carry a subject to policy agenda prominence.” indeed, as noted, the sudden prominence of energy in – did not lead to a major policy change, but the return of gas lines in caused a large jump in “indicators of attention,” and polls showed widespread belief that the problem was not going away. thus – saw a significant shift in energy policy in the u.s. and passage of dramatic, costly energy legislation. in this case, ms demonstrates how multiple related shocks could lead to a major policy change, although it does not suggest that a second (or any subsequent) episode must lead to major change nor does it mean that a one-time crisis will never have a major impact. according to this theory, there is no sequence that predictably goes from crisis to major policy change—or not. the unanswered questions are when and whether those involved in the policymaking process are able to identify the “open window” of a “choice opportunity” and then be able to also “couple the streams” (schlager, ). it is also unclear just who will be the decision maker and what information will most directly affect the outcome. . . . punctuated equilibrium shocks and crises play a key role in punctuated equilibrium theory (pet) as well. in pet, normality in the policy sphere is “stasis,” a quiet equlibrium (true et al., , ). as with ms, pet posits the potential for policy change when a shock (a punc- tuation) reorders a stable policy agenda. with increased attention and public concern now paid to the problem the shock has high- lighted, there may consequently be a change in the “policy image.” in other words, the punctuation leads to an altered understanding of the problem at hand and what, therefore, policy is supposed to accomplish. this does not mean that everyone has the same understanding or sees the outcome in the same terms. but the shock alters the issue's place on the public policy agenda—perhaps —precipitating a major policy change. at the same time, raising an issue's profile does not imply any particular solution, and in fact it does not imply that there is a solution, given that an issue may be highly technical. an issue's prominence means intense attention from policy entrepreneurs who have varying understandings of the problem and varying approaches for resolving it. ultimately though, whether a major change occurs or not, seems to reflect the relative strengths of positive and negative feedback effects; if the former predominate there will be change while the latter will push the policy “back to its original position” (repetto, , ). also, change will depend on whether or not the “internal dynamics” of the policymaking system are close to “a tipping point” whereby exogenous events can induce significant changes in policy (brock, ). but the consequences of a given shock are not known at the outset. pet argues that various events, ranging from serious crises to “rela- tively minor” occurrences, may “catch fire.” but what actually leads to an issue catching fire? the intensity of a shock or the persistence of a shock's effects (i.e. a crisis) would appear more likely to generate the “fire” that leads to policy change. retrospectively, however, one can argue that the – embargo event, for example, changed the image of energy, which had been a relatively minor concern and relegated to a low posi- tion on the policy agenda. it was, however, thrust to the top in late and then after falling for most of the rest of the decade it returned to prominence again in . at that point, in the “spotlight of macropolitics” and in the midst of a perceived crisis, the energy issue “caught fire,” changed the thinking of policy- makers (true et al., , ) and added new interests to the debate “in an environment of changing issue definitions and heightened attentiveness by the media and broader publics” (jones, , ). but only in retrospect is it easy to see why the energy issue “caught fire;” the fall of the shah in late did not in itself suggest any particular direction for u.s. energy policy, much less the major legislative program that passed in . . . . advocacy coalition framework a framework is intended to be broader than a theory. according to elinor ostrom, frameworks provide a broad set of variables, rules and models that can be used to compare the explanatory power of theories from multiple disciplines (ostrom, ). the advocacy coalition framework (acf) seeks to be a general “fra- mework” for analysis of policy and policy change, but has typically see for example, kingdon ( ) and repetto ( ). this concept is borrowed from evolutionary biology, particular the work of gould and eldredge ( ). p.z. grossman / energy policy ( ) – been referred to as a theory (schlager, ) and is often grouped with ms and pet as leading contemporary theories of the policy process. in essence, acf focuses on the actions and beliefs of “policy subsystems,” consisting of “public and private organiza- tions who are actively concerned with a policy problem.” coali- tions are groups within a policy subsystem “who share a set of normative and causal beliefs and who often act in concert” (sa- batier, , ). acf emphasizes policy-oriented learning over time and “theories about how to achieve [policy] objectives”— including for some, the objective of blocking policy change. learning leads in general to minor change, while the “necessary condition for major change is a transformation of external factors,” (capano, , ), mainly, “external perturbations or shocks” (sabatier and weible, , ). shocks may cause shifts within subsystems causing dominant coalitions to be replaced by what had been a minority coalition, altering agendas and core beliefs (sabatier and weible, , – ). sabatier ( , ) notes how the arab oil embargo depressed the american auto industry and that in turn moved the united auto workers union out of the advocacy group for clean air policies and into a very different coalition that opposed more stringent controls on auto emissions. in the acf, shocks and crises can affect policy in three ways: first, they can lead to the redistribution of political resources; for example, a crisis may “tilt the balance of power within the sub- system, paving the way for new actors to influence policy- making…” second, if members of a minority coalition are “skillful” enough to exploit the unexpectedly altered conditions they may “advance their core beliefs in policymaking.” and finally, members of the dominant coalition might reconsider their beliefs in light of a crisis (nohrstedt and weible, , ). nohrstedt ( ) argues that, to cite one instance, the three mile island nuclear power plant event in in pennsylvania led to a rise in antinuclear sentiment in sweden and in turn the vacillation by leading mem- bers (social democratic party officials) of the pronuclear power coalition. this ultimately influenced the pronuclear coalition to agree to a referendum on nuclear power, which led to a reversal of nuclear power policy. although acf (as with ms and pet) provides insights into the way crises impact policymaking, it also leaves an important question unanswered: why does one shock or crisis lead to major policy change while another does not? according to nohrstedt ( , ) “[m]ajor policy change in the wake of external shocks is more likely if an incumbent coalition member either perceives them as threats to basic interests or as an opportunity to advance basic interests.” yet that, too, is open to interpretation and ac- cording to nohrstedt is somewhat at odds with the main thrust of acf thinking that downplays “interests” assuming instead that subsystem participants are motivated more by “policy-oriented goals” and core “belief systems.” but these have no ready metric (hann, ), and acf like ms does not give a way of identifying the kind of information that will be crucial to the policy outcome (james and jorgensen, ). ultimately, as schlager ( , ) argues, in acf, ms and pet analyses, it is basically serendipitous whether or not an event, however dramatic, leads to major policy change. . . energy-crisis models of policy change . . . ambivalent majoritarian while the models and theories discussed above often refer to energy or environmental shocks and crises, ahrari ( ) offers a model to explain the legislative outcome specifically of an energy crisis. in this model, energy legislation that had been defeated in the absence of a crisis not only passes but does so by large ma- jorities when an energy crisis is notably prominent. his model, what he calls “ambivalent-majoritarian,” is strictly crisis-driven. he uses as the exemplar of his model the major synthetic fuels bill passed by the u.s. congress in . synfuels legislation, during the ford administration, had been defeated in congress in the mid- s. that bill, a limited policy of loan guarantees for prototype synfuels plants lost in the house of representatives by one vote. but the much more grandiose synfuels bill offered in the midst of the – energy market disruption passed over- whelmingly ( - in the house), apparently committing the government to spending $ billion ($ billion dollars) toward synthetic fuels demonstration and commercialization. ahrari ( , ) claims that this outcome was due to the fact that “under crisis conditions involving a domestic policy [decisions are] made by a larger-than-usual (i.e. a crisis) coalition of legisla- tors. …the crisis coalition comprises legislators who remained ambivalent about the correctness, feasibility and even rationality of this policy, but voted for it only as a response to a crisis.” given that ambivalence, such major policy innovations are likely to be impermanent. thus, when the sense of crisis ended and what ahrari refers to as a “‘normal’ environment” (that is, in- crementalism) returned, the synfuels program was abandoned. of course, this argument gives only a very general answer to the question of when such a coalition will form, and produce major policy changes. essentially it seems that the key is that a condition must cause discomfort among voters that is intense and protracted. the gas lines with continually rising prices left pol- icymakers little choice but to act—though it is difficult ex ante to define where that point of action might be. . . . the “do something” dilemma grossman ( ) also seeks to explain outcomes in legislative policymaking with respect to energy specifically in a u.s. context. this model is similar is some respects to downs's issue-attention cycle but it focuses more directly on the behavior of policymakers, particularly u.s. legislators. it posits a crisis-policy process (like downs) as a series of steps, but it argues the process may stop, may advance to a stage of incremental or symbolic policy action or reach the end in major policy change. the model hypothesizes that an energy problem elevated to the stature of a crisis is processed by elected policymakers as a threat to their office. as discomfort from an energy problem rises, constituents demand action, and elected officials must “do something.” others (e.g. boin and thart, ; higgs, ) have noted a “do something” dilemma or “urgency mechanism” (keeler, , ) faced by policymakers in a crisis. but in grossman's model prompt action need not mean a major revision in policy. instead, policymakers need to show immediate “engagement” with the problem but are likely to do so rhetorically at first, so if the crisis is in fact only a very short-term energy market shock, nothing need be done and elected officials avoid blame for having chosen a policy course that quickly was shown to be mistaken (weaver, ). if the crisis persists, however, in grossman's model, there is a second stage, “expression of intent,” whereby policymakers com- mit to various changes in policy intended to relieve the impact of the crisis or solve it. some of these policy commitments are wholly symbolic (mayhew, ; cobb et al., ; lyons, ; grossman, weyant ( ) explores this aspect with respect to natural gas policies in the s and s. for example, jenkins-smith and weimer ( ) show how policy analysis was used as a tactic to delay and reverse actions with regard to the u.s. strategic petroleum reserve. after mayhew ( , ) this model sees a legislator as a “single-minded [seeker] of reelection.” p.z. grossman / energy policy ( ) – ), such as a suggestion of turning off the christmas lighting in washington, dc during the oil embargo or for congressional resolutions such as, h.con.res. , a “concurrent resolution ex- pressing the sense of the congress with respect to the present world energy crisis” introduced in late october . the final stage of the model is “legislative action,” whereby policymakers are compelled by continued demands for action to vote for legislation. the longer the crisis has gone on, the higher the probability that there will be legislation that will represent a major change in policy. thus various shocks in (first the disruption from regime change in iran; then the iran hostage cri- sis) led to the perception that the energy crisis was unresolved even in and required a far-reaching solution. this in turn resulted in passage of sweeping energy legislation that created goals for synthetic fuel production with expected expenditures of vast sums. if, on the other hand, in the time from when a crisis is experienced acutely to the time preceding legislative action, the energy market resolves the most discomforting factors (in , for example) energy legislation likely will be incremental if any is passed at all. given that market resolution of energy crises has typically occurred within a few weeks or months of the initial shock, significant departures in u.s. energy policy have been rare and tend to be short-lived even when they are made policy. ulti- mately, the default position of u.s. energy policy since the s has been to let the market decide. . . economic crisis policy models economists have often grappled with models of crises but these have tended to focus on financial-monetary crises or recessions- depressions, and the policy tools to cope with them. energy crises have in some instances entered financial crisis/business cycle de- bates, particularly the work of hamilton ( , , ), who has suggested that nearly all u.s. recessions since the end of world war ii have been in some sense driven by rising oil prices. such analysis typically will lead to a discussion of the efficacy in such circumstances of standard counter-cyclical monetary or fiscal policies. general political models are also part of the economic litera- ture. in fact public choice theory is essentially an examination, through a basic economic model of choice by rational actors, of the behavior and incentives of officials at all levels of government as well as the behavior of voters in the political process (buchanan and tullock, ; mueller, ). but for the most part they do not focus on crises or policy responses to them. still, as noted earlier, economists have created models, groun- ded in economic theory, applicable to analysis of energy and en- vironmental crises and the policies that emerged from them. . . . rational choice with ignorance according to congleton ( ) analysis of choice in time of crisis—i.e. policymaking—is largely absent in the public choice literature for an important reason: while a rational choice model permits “shocks of one kind or another…” he argues, it rules out crises because these involve not just shocks but “unpleasant sur- prises calling for urgent responses.” in order for rational choice to provide insight into crisis policymaking one must move “beyond the usual assumptions of” rational choice models (congleton, , ). in essence what separates a crisis from a shock is ignorance. crises do not, he claims, change “fundamental political incentives” (congleton, , ); all actors in the political sphere will still try to maximize their utility and will choose to act rationally in a crisis based on what information is available to them. but “[i] gnorance simply implies that the list of possibilities considered may be very incomplete and that the understanding of causal re- lationships…may be erroneous in many respects” (congleton, , ). what this means, congleton asserts ( – ), is that ignorant, but rational, individuals can make the right decisions when they have sufficient data, but “rational decision makers will make systematic errors insofar as they are ignorant of relevant variables and relationships” (emphasis in the original). in addition to ignorance, there is of course urgency, which means in this model, not only that many crisis-driven policies are mistaken, they may also generate future crises because “mistakes have un- anticipated effects” (congleton, , ). congleton models ignorance by including a term, z, in in- dividual utility functions. z is a factor that initially unobserved. it might be stable or not, and its path over time is unclear. in other words, say observations give some clarity to z, but if its future course remains unclear, policies fitted to z at time (t) may well be ill-fitted to z at (tþ ). “whether z can be controlled or not policy mistakes are likely to continue until both z and the policies for addressing z are well understood, and this may take a long time” (congleton, , ). in the meantime, due to ignorance, “times of crisis…present interest groups inside and outside government with unusually great opportunities to profit by influencing the details of policies adopted privately within the legislature and publicly through media campaigns” (congleton, , ). energy policy development in the u.s. has witnessed sys- tematic policy errors stemming in large part to a misinterpretation of the events surrounding the arab oil embargo (grossman, ). the standard energy narrative for the last years is that the u.s. has been “dangerously” dependent on world oil markets, markets that are controlled by the nations of the opec oil cartel, and by virtue of this dependence, members of this cartel can use oil as a weapon to coerce america into changing its national po- licies; thus the oil market is a threat to national sovereignty and to the american economy. the only solution to this threat is said to be energy self-sufficiency. this narrative represents the “story line” that has been widely accepted and has remained even in the face of much evidence that contradicts it (grossman, ). policy initiatives, however, have taken the narrative as the starting place. by adhering to this ver- sion of events, policies have failed but are repeated in the midst of, or in the aftermath of, the next perceived energy crisis. this in turn has constituted a path dependent policy process that inevitably fails to benefit society but does benefit alert policy entrepreneurs (grossman, ). any significant energy problem revives the narrative and gives legislators, energy industries of various kinds, farmers, labor groups, environmentalists, government agencies, and coalitions of these groups the chance to benefit from the en- ergy policy process (holcombe, ). . . . crisis opportunism the conclusion above fits with the work higgs ( , ). higgs has studied the way in which crises are utilized by for example, in , congress passed the energy policy and conservation act that was thought by many including most of president gerald ford's aides, to be weak legislation. in , crises with respect to oil prices and electric power in california led to proposals for significant energy policy changes, but by autumn oil prices were falling and california had a surplus of electricity; no new energy leg- islation passed the u.s. congress. bernanke et al. ( ) argued that the monetary response to an oil price shock had the greater impact on the business cycle than the price shock itself—an argument hamilton rejected (hamilton and herrera, ). as noted earlier, the rational actor of such economic models is replaced in political science as well as some economic approaches by a “boundedly” rational actor, with limited ability to calculate optimal behavior even when nearly complete information is available (simon, ). p.z. grossman / energy policy ( ) – “opportunists inside and outside the formal state apparatus” to expand the reach and scope of governmental authority ( , ). crises alter policies—some of which are imposed “without formal proceedings at all”—lead to new bureaucracies, and new laws. the latter are especially likely to endure because, “rarely does the general public take much interest in a law's repeal and public apathy fosters legislative inertia” (higgs, , ). higgs points to an energy example. in late , in the midst of a national energy crisis, president richard nixon created by ex- ecutive fiat the federal energy office in the executive office of the president. in may , congress approved a larger energy bu- reaucracy, the federal energy administration, which soon had a staff of . in , it was subsumed in the cabinet-level de- partment of energy and the staff size rose to about , . while energy laws have often been ineffective, few have been repealed, and extant legislation even if largely ignored for a time can become a lucrative path for policy entrepreneurs (or opportunists, as higgs terms them) with a change in administrations. indeed, con- troversy in the s over benefits to the wind industry originated in legislation passed in . higgs writes that, of course, crises are by definition perilous occasions but “the greatest danger often resides not so much in the perceived threat as in the government's osten- sible measures to fend it off” ( , ). . . models and theories of the policy process: what do they explain? how well do these theories explain the progress of energy policy not only in the u.s., but also in other developed countries with different democratic institutions? the next section con- siders two cases of energy shocks and crises, and their outcomes, from various perspectives. all of the models and theories have something to add to an understanding of how shocks and crises affect the policy process. most of the models seek to examine short-term effects. the models of charles jones and downs were intended “to account for phenomena” that incrementalism did not. the models provide insights into the immediate impact of shocks and crises to the policy process. ahrari and grossman are more interested in out- comes but in similarly shortened time frames. few of these models, however, explicate how shocks and crises impact policy- making in the long run. congleton's is one model with significant long-run implications. as noted, it could explain the observation (grossman, ) of a -year misinterpretation of the – energy market event. theories such ms, pet and acf are more precisely intended to offer an expansive, long-run view of the policymaking process. all three can be utilized in analyzing policies and policy outcomes of energy issues as they have unfolded over the course of years. ms and pet specifically target the impacts of shocks and crises on policy, how in fact a shock can upset a system fundamentally and send policy on a different trajectory that may require another shock to divert. not surprisingly both have been used to illustrate policy change because of disruptive energy or environmental events. with acf, which is especially useful in explaining policy processes and change over time, the role of shocks and crises is more ambiguous. some acf scholars regard shocks (both internal shocks to subsystems as well as external socio-economic events) as pivotal in understanding policy change. but others assert that learning as the crucial factor in the policy process (see the dis- cussion in nohrstedt and weible ( )). there seems to be, however, sufficient flexibility in the acf to allow both views (as well as a synthesis of them) to coexist within the acf. acf's flexibility has meant that it has had greater use than the other models and theories in the analysis of policymaking in different institutional settings. it has been employed to examine a range of international energy and environmental policies: for example, u.s. natural gas policy (weyant, ), swedish nuclear policy (nohr- stedt, ), and polish environmental policy (andersson, ). there is no reason, however, why multiple perspectives should not be applied to the same problem. as dowding ( ) observed different theories in the policy literature are often complementary not contradictory. ostrom ( , ) in fact has argued that there is an “overall strength [in] using multiple methods to attack tough analytical puzzles.” that energy policy often involves complex “puzzles” suggests that such an approach to understanding policy and policy change would be wise. . energy crisis policymaking: two cases in this section, two cases are examined from the standpoint of the models and theories noted in section . the first, u.s. energy policy during, and in the aftermath of, the crisis in iraq in – , is an example that can readily be construed from various perspectives. acf is utilized primarily to untangle the forces be- hind german policies that resulted in the energiewende, but the focus on one theory is intended only to be illustrative. there are undoubtedly insights that could be brought to bear from other models and theories noted here. . . the comprehensive energy policy act of energy issues had fallen into the background in the u.s. in the late s, but saddam hussein's decision to invade kuwait in early august led to a united nations boycott of iraqi and kuwaiti oil, removing four million barrels per day from the market. the price of oil, around $ per barrel (bbl.) at the end of july had risen to over $ /bbl. by september. there was speculative buying and widespread fears of the return of gasoline lines. these did not recur since they had been the result of u.s. price controls, which were abolished in —meaning that shocks like the one ex- perienced in raised prices but did not lead to shortages. whether or not this event constituted anything that should have been called an “energy crisis,” it was portrayed that way and the rhetoric of crisis was notable among policymakers during the fall of . as expressed by one member of congress, if there was a return of gasoline lines, it would lead to a “revolution” in their districts (cited in grossman, , ). but since there were no gasoline lines, the rhetoric soon was out of line with the percep- tions of the public. nonetheless, the price spike and the subsequent gulf war put the energy issue back in the spotlight, and various coalitions and policy entrepreneurs came forward demanding major change. but the price run-up was reversing by winter and so was the sense of crisis. the gulf war fighting lasted only six weeks, and although many radical ideas were pushed forward, revealing signs of “speculative augmentation” (jones, ) (e.g. a bill by re- presentative harold volkmer (d-mo) to achieve energy in- dependence by the year ), a majority coalition in congress for major change could not be solidified. after the alarm and euphoric solution proposals (as in downs, ), energy legislation did proceed but with greatly reduced urgency. the issue did not (from a pet viewpoint) “catch fire,” because the feedback—for example, one might also add: do these theories help explain policy in developing countries including those like india that have long-standing democratic institutions as well as others with weak or non-existent democratic institutions? all of the above theoretical constructs and models assume some kind of larger group of policymakers beyond a single dictator or ruling clique. whether these analytic tools can explain policy across regime types would be an interesting exercise but is one beyond the scope of this paper. p.z. grossman / energy policy ( ) – waning public and media interest—was mostly negative. over the -month period from the end of the gulf war to final passage of legislation, the various groups in and out of government contested the contents. a fossil fuel coalition sought to expand exploration and production into the arctic national wildlife re- fuge (anwr) while environmentalists argued for a major expan- sion of the corporate average fuel economy (cafe) standards. much of the dispute was couched in terms of the american energy self-sufficiency—a politically popular theme, even though mostly undefined and ill-considered—but all radical policy ideas were soon either watered down or removed entirely. in effect, congress soon was engaged in a process that would lead either to a complete failure to affect any policy change or to a bill that offered small benefits to various interest groups. it was difficult for legislators and policy entrepreneurs to convince the public (and even others in the policy subsystem) that a crisis still existed; the public cared mostly about the price of gasoline but that problem had been cured in by market forces. conse- quently, there was no general movement for any major policy change, or for some time, even for changes that were merely in- cremental. a coalition of coal state interests seeking special ben- efits, farming lobbies and their allies demanding expansion of in- centives for ethanol, and other narrow interests also seeking rents, disrupted an easy passage. the comprehensive energy policy act of (epact ) was signed into law finally on october , , but it was neither comprehensive nor much of a change in energy policy. one senator called it simply an expression of the “status quo…in energy policy.” this outcome suggests that if a “window” did open in , it quickly closed. there was no inclination to couple the streams; with the most visible issue resolved, radical policies could have been regarded as solutions in search of a problem (kingdon, ). there was little opportunity for minority coalitions to exploit the crisis; no reason for ambivalent legislators to vote against their better judgment (ahrari, ); and no demand from constituents by spring that government “do something” (grossman, ). epact , as downs and higgs would have predicted, did expand some government programs and create others. one of these, a tax benefit for wind generated electricity, as noted earlier, would offer opportunities for policy entrepreneurs in later years. arguably, epact embodied congleton's systematic errors as it expanded programs that were based on ignorance initially. but to interpret the longer-term impact of the legislation and trajectory of policy in its aftermath, a scholar would require broader theory such as ms, pet or acf. these could be tested using models based on hypotheses about how policy systems would be thought to change after an event like the gulf war. . . energiewende the theories and models noted in this article were largely de- veloped by scholars in the u.s. using as examples events processed through american institutions. however, these ideas on policy have been employed (and at times amended) to interpret policy processes and change in other countries. the advocacy coalition framework (acf) has, in particular, been utilized by scholars in- ternationally to provide a theoretical structure to explain the course of important public policies (sabatier, ; weible et al., ). one significant example has been its use in identifying the various events and forces that led to the inception and subsequent expansion of the german energy policy, energiewende (e.g. ja- cobsson and lauber, ), a policy that has developed over the past years. the term “energiewende,” meaning energy transition, was first coined in a study by germany's institute for applied ecology that outlined an energy future with no oil or nuclear power, and that emphasized energy efficiency and renewable technologies. the institute itself had emerged from germany's anti-nuclear movement, which had gained a public platform for itself begin- ning in the s through mass demonstrations against new nu- clear power facilities. this went against the predominant majority coalition that saw nuclear power as an important means of re- ducing dependence on imported oil or natural gas. over the next three decades, the energiewende became the dominant policy of germany—a major shift from policies that had predominated from the post-war era through the s that emphasized domestic coal as well as nuclear power. during the s, a minority coalition coalesced around the anti-nuclear position, and a new political party, the greens, began to contest elections both regionally and nationally. but the key to the anti-nuclear coalition's ascendency was the nuclear disaster at chernobyl in the soviet union in . the shock soon became a crisis marked by a sense of threat, in the form of a radioactive cloud that passed over portions of germany. there was a pervasive sense of fear about the likely effects this radioactivity would bring. coalitions moved quickly to address the issue. the majority pronuclear coalition, led in government by the largest party, the christian democratic union, and outside, represented by utility executives and nuclear power experts, argued at first that there was little danger of a chernobyl-type disaster domestically be- cause germany used reactors that were far less likely to fail. they also claimed that the radioactive chernobyl cloud would not taint germany's food supply. members of government were shown in the media eating salad to prove there was nothing to worry about. opposition greens, unsurprisingly, called for immediate end to nuclear power production, while the social democrats (the second largest political party) argued that “nuclear power [should be] a transitory solution to the energy problem” (krohn and weingart, ). radiation, invisible to the senses and with impacts that might not appear for decades, can in itself engender fear and uncertainty. radioactivity and its effects “have to be made ‘visible’ by the media and have to be defined, interpreted and framed by politicians, scientists and social movements” (koopmans and duyvendak, , ). in germany, these forces only compounded the sense of crisis. confusing, sometimes contradictory statements by state (länder) and federal government officials, heightened public an- xieties and social groups politicized the issue in ways that played to public fears (renn, ). government bureaucracies that should have brought clarity did not. as a frankfurt newspaper opined, “confusion in the public agencies creates fear” (quoted in krohn and weingart, , ). there was a dramatic shift in public opinion. prior to the chernobyl, polls showed that percent of the west german public endorsed the majority coalition's policy in support of nu- clear power. within a week of the first reports of the disaster, public backing dropped dramatically to percent; percent were now opposed, most in favor of a gradual shutdown, but percent believed all nuclear power facilities should be dismantled at once (krohn and weingart, ). from an acf perspective, this represented a “redistribution of political resources,” one of the possible “causal mechanisms that link events to major policy change” (nohrstedt and weible, , ). even when the sense of crisis had abated, support for nuclear power languished. two reports at about the same time as the chernobyl disaster made non-carbon (and non-nuclear) energy technologies seem a realistic (to some a necessary) alternative. a government study of energy released in , “concluded that only reliance on re- newables and efficiency would be compatible with the basic senator john chafee (r-ri), congressional record, oct. , . p.z. grossman / energy policy ( ) – values of a free society” (jacobsson and lauber, , ). the same year a german physical society document warned of a po- tential climate catastrophe from anthropogenic global warming (agw), an idea that also captured the attention of the german public, and provided an impression of a second crisis. by the early s germans were far more concerned about climate change than any other nation in europe (brechin, ). with over percent support for action on climate change, the issue soon im- pacted the dominant coalition; the federal chancellor helmut kohl declared climate change the most urgent environmental is- sue, an example it would seem either of a wish to protect his party's election prospects or of policy learning, leading to a re- consideration “policy core beliefs” of kohl's party, the christian democratic union (nohrstedt and weible, , ). in any event, it led to a widespread agreement within the broader policy sub- system that “energy use had to be profoundly changed” (jacobsson and lauber, , ). the anti-nuclear coalition embraced renewables, gaining in the process support from renewable industry groups, academic re- searchers, green ngos and think tanks, and even the owners of small hydroelectric facilities. in , the german bundestag pas- sed the electricity feed-in law ( ) to guarantee a return on renewables, succeeding against a coalition that opposed “sub- sidization of technologies unfit for the market” (quoted in ja- cobsson and lauber, , ) that included the major electric utilities and the ministry of economic affairs. in fact, the utilities challenged the law in various venues, which slowed development of a transition to renewables, and with the integration of east and west germany dominating the agenda in the early s, little more was done to push an energiewende. but in , a government proposal to reduce feed-in tariffs drew massive protests that brought greens together with labor unions and religious groups and led to large, dramatic demon- strations. in , the greens entered the majority parliamentary coalition for the first time and pressed their energy agenda. the energy sources act ( ) increased the incentives for renewables and promised a phase out of all of germany's nuclear power fa- cilities. by the mid- s, germany was the center of activity for renewable energy projects including the largest solar photovoltaic array in bavaria and the installation of , mw of wind capa- city. the official policy goal was (and still is) for percent re- newable electricity by . despite the apparent strength of anti-nuclear/pro-renewables coalition, the german government under prime minister angela merkel decided in to extend the life of existing nuclear power plants. but then a new shock, the fukashima nuclear power plant disaster in , renewed the german public's antipathy for nu- clear power, and provoked an almost immediate policy reversal. the disaster also came just before state elections and it has been argued that merkel felt obliged to protect her party's electoral chances (blackmore, )—a sign perhaps that she saw this shock as a political threat. but whatever the rationale, merkel announced the permanent closure of several nuclear facilities and the phase out of the rest by —even though this has meant at least temporarily an increase in carbon emissions from german utilities forced to switch to coal. the anti-nuclear, pro-renewables coalition remains the major- ity, retains the support generally of the public, and after managing to affect a major change in energy policy, has directed energy policymaking for the last þ years. but there are challenges to this group, especially from german industry, which now pays higher electricity costs than firms in most other industrialized nations, and consumer advocates and charitable groups who see the feed-in tariffs as a regressive tax affecting the poor most of all. whether they can realign german politics and make a dif- ferent sort of change may depend on whether they, as the greens before them, can take advantage of the next energy shocks and crises. but a key point to take from the german experience is that unlike in the u.s., energy-related crises have led to significantly altered energy policies that have endured, changes in energy markets notwithstanding. then again germany has undertaken major changes in energy policy (a paradigm shift, according to helm ( )) as a solution to an ongoing environmental crisis— climate change—that is at least for now still salient with the ger- man public. although acf is clearly useful in explaining the advent of en- ergiewende, some scholars argue that any theory needs an in- stitutional overlay to highlight the differences not only between the u.s. and europe, but also among european countries. there has been some convergence of law within the eu, but there remain differences both in formal laws and, perhaps more importantly, in traditions and customs that inform choices differently even in countries as economically and geographically close as, say, ger- many and the netherlands. according the jacobsson and lauber ( , ) there must be an appreciation for a society's “deeper historical and cultural influences,” what north ( ) terms a so- ciety's “informal institutions.” this argues for incorporating into any inquiry of policy processes a comparative institutional analy- sis, particularly with regard to the ways “cross-national variations” impact resultant policy (koopmans and duyvendak, , ). . conclusions the theories and models discussed in this paper provide some general and very useful insights into the formation, character, outcomes and impacts of energy crisis policymaking and indeed energy policymaking generally. however, no one complete theory of crisis policymaking answers all questions, encompasses all of the variables, or explains all of the processes that might go into the evolution of energy policies across time and across the world. but a general idea of what theory tells us might be summarized as follows: a crisis means that “normal” processes of policymaking have been disrupted—or at least that there is the perception of such a disruption. officials, whether thought of as fully rational but ig- norant, or as boundedly rational and thus limited in their ability to process information, due to widespread alarm, are confronted by a sense of urgency to act. but both the major issues of a given crisis and any solutions to it are at least unclear, and often conceptually and technically beyond their abilities (as well as those of the general public) to understand. in many cases, markets resolve the sense of crisis. but crises provide an occasion for major change (e.g. energiewende), particularly if the crisis seems to persist. al- though why the same crisis experienced in different countries leads to paradigm shifts in one place but little change in another, is a question requiring much more analysis than a review article can accommodate. theories and models may grapple with this situation differ- ently, some illuminating only a few specific variables, others trying for a broader understanding of processes and outcomes. policy processes are complex, and theories and models are by definition restrictive means of organizing analysis. a broad framework that as of early april , the federal government had cut subsidies and in- troduced other “reforms” that began immediately to slow the growth of “green” electricity. (see the article at: http://www.reuters.com/article/ / / /ger many-energy-idusl n n p .) for a discussion of energy issue salience see lowry and joslyn ( ). as koopmans and duyvendak ( ) point out, in the netherlands there was no “detectable” change in public actions in response to chernobyl. p.z. grossman / energy policy ( ) – http://www.reuters.com/article/ / / /germany-energy-idusl n n p http://www.reuters.com/article/ / / /germany-energy-idusl n n p would “specify assumptions, identify scope, establish general ca- tegories and definitions of concepts and variables, and provide a shared language for scholars…[would allow] for the comparison and further refinement of theories” (schlager and weible, , ). and further: “frameworks identify the elements and general relationships among [the] elements that one needs to consider for institu- tional analysis and they organize diagnostic and prescriptive inquiry. they provide a general set of variables that can be used to analyze all types of institutional arrangements. frameworks provide a metatheoretical language that can be used to com- pare theories. they attempt to identify the universal elements that any theory relevant to the same kind of phenomena needs to include” (ostrom, , ). my own view is that energy policy requires its own framework. this would encompass various theories and models of how shocks and crises reorder coalitions, change policy dynamics, and lead to new (if not always unambiguous) understandings of what the policy process can actually achieve. extant frameworks, acf (as it has evolved), or perhaps ostrom's institutional rational choice (irc), which to date has been applied mainly to property regimes, might be adapted to crisis analysis (schlager and blomquist, ; ostrom, ). but any such framework for energy policy would, like irc, have to embrace institutional as well as behavioral the- ories and permit the kind of comparative institutional analysis noted in the section above. an effective energy policy framework could also test new theories of the policy process, comparing these approaches with older concepts. one recent addition to the lit- erature that seems promising in this regard is the narrative policy framework (npf) (shanahan et al., , ), which analyses the policy process as a competition between “stories [that] relevant actors…strategically employ.” npf provides a way to parse the narratives—e.g. the u.s. dependency narrative—that underlie so much energy policy. though posited as a framework of its own, narrative analysis has been presented by its creators as a theore- tical approach “applicable to acf research” (shanahan et al., , ) and could no doubt serve as a separate theory and set of models to test in a different framework. there are, in other words, many ways to finally structure a framework for the analysis of energy policy particularly policy in the face of shocks and crises, a means to study policy change in both the short and long term. but consider such a framework still work-in-progress. acknowledgments for comments, suggestions, reactions, and encouragement, the author would like to thank daniel cole, lee lane, william lowry, four anonymous reviewers, and energy policy editor, lorna greening. references ahrari, m.e., . the paradigm of crisis decision making: the case of synfuels policy. br. j. polit. sci. , – . akins, j.k., . the oil crisis: this time the wolf is here. foreign aff. , – . andersson, m., . change and continuity in poland's environmental policy. kluwer academic publishing, dordrecht. baumgartner, f.r., jones, b.d., . agendas and instability in american politics, nd ed. university of chicago press, chicago. baumgatner, f.r., jones, b.d., . agenda dynamics and policy subsystems. j. pol. , – . baumgartner, f.r., jones, b.d., . agendas and instability in american politics, st ed. university of chicago press, chicago. bernanke, b.s., gertler, m., watson, m., . systematic monetary policy and the effects of oil price shocks. brookings papers on economic activity, pp. – . bernstein, m.h., . regulating business by independent commission. princeton university press, princeton, nj. blackmore, d., . abandoning nuclear power: a social constructivist analysis of germany’s response to fukushima. j. polit. int. stud. , – . boin, a., thart, p., . public leadership in times of crisis: mission impossible? public adm. rev. , – . boin, a., thart, p., stern, e., sundelius, b., . the politics of crisis management: public leadership under pressure. cambridge university press, cambridge, uk; new york. braybrooke, d., lindblom, c.e., . a strategy of decision; policy evaluation as a social process. free press of glencoe, new york. brechin, s.r., . comparative public opinion and knowledge on global climatic change and the kyoto protocol: the u.s. versus the world? int. j. sociol. soc. policy , – . brock, w.a., . tipping points, abrupt opinion changes and punctuated policy change. in: repetto, r.c. 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(ed.), theories of the policy process. westview press, boulder, co, pp. – . p.z. grossman / energy policy ( ) – http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - 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( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref http://refhub.elsevier.com/s - ( ) - /sbref 	butler university 	from the selectedworks of peter z. grossman 	 	energy shocks, crises and the policy process: a review of theory and application 	energy shocks, crises and the policy process: a review of theory and application 	introduction 	what is a “crisis”? 	theories and models of crisis policymaking 	from incrementalism to speculative augmentation and the issue-attention cycle 	public satisfying-speculative augmentation 	the issue-attention cycle 	three post-incrementalist theories of the policy process 	multiple streams 	punctuated equilibrium 	advocacy coalition framework 	energy-crisis models of policy change 	ambivalent majoritarian 	the “do something” dilemma 	economic crisis policy models 	rational choice with ignorance 	crisis opportunism 	models and theories of the policy process: what do they explain? 	energy crisis policymaking: two cases 	the comprehensive energy policy act of 	energiewende 	conclusions 	acknowledgments 	references science ameican association for the advancemnt of science science serves its readers as a forum for the presentation and discussion of important issues related to the advance- ment of science, including the presentation of minority or con- flicting points of view, rather than by publishing only material on which a consensus has been reached. accordingly, all ar- ticles published in science-including editorials, news and comment, and book reviews-are signed and reflect the indi- vidual views of the authors and not official points of view adopted by the aaas or the institutions with which the au- thors are affiliated. publisher: alvin w. trivelpiece editor: daniel e. koshland, jr. deputy editors: philip h. abelson (engineering and applied sciences); john . brauman (physical sciences) editorial staff managing editor: patricia a. morgan assistant managing editors: nancy j. hartnagel, john e. ringle senior editors: eleanore butz, ruth kulstad associate editors: martha collins, barbara jasny, katrina l. kelner, edith meyers, phillip d. szuromi, david f. voss letrs editor: christine gilbert book reviews: katherine livingston, editor; deborah f. washburn this weekin science: ruth levy guyer contributing editor: lawrence . grossman chiet production editor: ellen e. murphy editing department: lois schmitt, head; mary mcdaniel, barbara e. patterson copy desk: lyle l. green, sharon ryan, beverly shields, anna victoreen production manager: karen schools assistant production manager: james landry graphics and production: holly bishop, eleanor warner covers editor: grayce finger manuscript systems analyst: william carter news staff news editor: barbara j. culliton news and comment: colin norman, deputy editor; mark h. crawford, constance holden, eliot marshall, marjorie sun, john walsh rearch news: roger lewin, deputy editor; deborah m. barnes, richard a. kerr, gina kolata, jean l. marx, leslie roberts, arthur l. robinson, m. mitchell waldrop european correspondent: david dickson business staff associate publisher: william m. miller, ill busines staff manager: deborah rivera-wienhold membership recruitment: gwendolyn huddle member and subscription records: ann ragland guide to biotechnology products andinstruments: shauna s. roberts advertising representatives director: earl j. scherago traffic manager: donna rivera traffic manager (recrulimnt): gwen canter advertising saies manager: richard l. charles marketing manager: herbert l. burklund sais: new york, ny : j. kevin henebry, broad- way ( - - ); scotch plains, nj : c. richard callis, unami lane ( - - ); chicago, il : jack ryan, room , n. michigan ave. ( - - ); san jose, ca : bob brindley, s. st. ( - - ); dorset, vt : fred w. dieffenbach, kent hill rd. ( - - ); damascus, md : rick sommer, shrubbery hill ct. ( - - ); u.k., europe: nick jones, + ( ) ; telex ; fax ( ) . information for contributors appears on page xl of the june issue. editorial correspondence, including re- quests for permission to reprint and reprint orders, should be sent to h street, nw, washington, dc . tele- phone: - - . advertising correspondence should be sent to tenth floor, broadway, ny . telephone - - or wu telex scherago. july i volume number io inexorable laws and the ecosystem it has been said that the three laws of thermodynamics can be paraphrased. first law: "life is a zero sum game." second law: "you can't win." third law: "you can't get out of the game." the same appears to be true of the global environmental problem. we have only one atmosphere whose balance between carbon dioxide, oxygen, and ozone is critical to our survival. we have one earth and ocean whose fertility and purity are equally important. increasing population and increasing industrialization pose threats to that environment, the consequences of which will fall on all, except for a few who plan to live out their lives huddled in rockets speeding toward mars. no area is more plagued with toxic logic or eutrophied emotions. highly developed countries are appalled at the destruction by poaching of the great lions and elephants of africa, but starving residents say that they are only doing what their ancestors did to survive. the world bank now recognizes that its loans may help encourage the destruction of rain forests, but recipients of the loans may consider farmlands more important than rain forests. in california there is a bitter war between residents of the north and the south over a plan to divert water to southern farmers at the expense of the natural beauty and possibly the environmental quality of northern regions. the tendency for each nation or village or region to point a finger and say,"they're no better than i am," will ultimately doom the ecosystem for all of us. the recent willingness of the u.s. finally to sign a treaty on atmospheric pollutants is a timely recognition that we are all in this atmosphere together. as the world population grows and as underdeveloped nations become more industrial- ized, the threat to the environment is going to increase, and very drastically. but before the self-righteous sermons begin, the united states might well examine its own policies to provide belt-tightening models. how can a highly industrialized nation, where there are often two cars per family, make a case to developing nations, where few have even one car, that the world can support no more cars? the suburban sprawl of the united states is continually overrunning the best farmlands of the country. yet a chicken in every pot and a home for every citizen is still one of the alluring goals of our society. are we willing to contemplate restrictions to our freedoms in order to preserve agricultural lands and to concentrate people in more urban areas, thus saving on mass transportation and diminishing the need for individual cars? that solution not only makes sense for the environment, but also for the energy crisis that is bound to comein the not-too-distant future. it is the kind of sacrifice, however, that might be difficult for any political party to support. with the problem outlined in global terms, it is clear that a rethinking of priorities is necessary. the population explosion has to move to top priority. there is no way that the problems from cars, chemicals, bad land use, and so on, will not accelerate if the population keeps increasing. there is an air of condescension and superiority if industrialized nations with near-zero population growth tell others to "grow no more," but many are coming to the same conclusions for reasons of political stability and economic well-being. second, better global planning and national priorities need to be established in transportation policy. third, containment of toxic wastes, acid rain, and other pollutants that poison the atmosphere, the waters, and the land will have to be initiated at high cost to all citizens. perhaps the politically feasible line is a negotiated equality of sacrifice. thus, it is easier for a wealthy nation such as the united states to apply rigid smog controls and develop the technology for waste disposal than an emerging nation such as south korea. a significant fraction of superfund should therefore be devoted to research that benefits all. emerging nations could make their major contributions to programs for effective population control and tailor the research and experience of others to their own pollution problems. through international treaties, steps toward more appropriate conservation and preservation mea- sures should be taken. cheap water and cheap air, like cheap oil, are rarely really cheap. usually one group of citizens must be subsidizing the needs of another group. it is time to take a global look at the policies and priorities that are dooming our ecosystem. in contrast to the paraphrased second law, we can win, but only if we recognize the truth of the first and third laws. we all win or lose together, and no one can be excused from the game.-daniel e. koshland, jr. july editorial o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ inexorable laws and the ecosystem daniel e. koshland jr. doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the is a registered trademark of aaas.sciencescience, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for the advancement ofscience by the american association for the advancement of science. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ impact and success of research infrastructures impact and success of research infrastructures steven krauwer clarin eric - - success and impact are not the same thing • success: to what extent do we manage to do what we promised to do. this is the typical project scenario, with given goal and time frame, where every step is under our control and responsibility. • impact: simon taller ( ) defines impact as “the measurable outcomes arising from the existence of a digital resource that demonstrate a change in the life or life opportunities of the community for which the resource is intended”. • taller’s focus was on the impact of digital resources, ours will be on research infrastructures (ris) for the social sciences and humanities & cultural heritage (ssh&ch). clarin a layered approach for ris in ssh&ch • economic impact: to what extent do the construction and operation of the ri generate economic activity in or around the ri • impact on the scientific landscape: how does the ri affect the life or life opportunities of ssh&ch researchers and practitioners (including students) • impact on research results: how does the landscape as changed by the ri affect the research results • societal impact: how do the research results that were obtained thanks to the ri affect society at large clarin economic impact • for distributed data infrastructures in ssh&ch there are hardly any significant economic benefits that follow from the construction and operation of the ri (as opposed to hard sciences) • commercial exploitation of ssh&ch research results obtained through the use of the ri may be possible, but it may be hard to demonstrate the role of the ri in the final products or services clarin impact on the scientific landscape (i) this is about the facilities and opportunities we as ris offer to researchers, practitioners and students – and therefore easy to measure qualitatively and quantitatively and to describe, and to formulate kpis. below some main features of clarin. • having a well-developed technical infrastructure populated with data and services is not sufficient, as in ssh&ch the digital transformation has only just started • in clarin we have, parallel to the technical infrastructure, our knowledge sharing infrastructure, which serves to facilitate knowledge transfer between all stakeholders on a european scale, covering a broad range of training activities • common standards create optimal opportunities to combine and re-use data and tools from different sources so that researchers can collaborate and build on each other’s results, and increase their collective scientific impact clarin impact on the scientific landscape (ii) • publication of examples of successful use cases should help to attract and inspire new users • collection and promotion of special families of language resources (e.g. newspaper texts, parliamentary records, social media and oral history) and tools to work with them should help to bring together researchers from different countries or disciplines for joint research projects clarin impact on research output this is about the uptake of what we offer by our users and the research and education results it leads to. • what we can measure and formulate kpis for is the number of users, course participants, visits, downloads, requests, etc • the extent to which researchers have successfully made use of our facilities for their research will only be visible and measurable if they give credit for it in their publications. developing and promoting proper citation habits is an important common action point for data ris. clarin societal impact this is about the extent to which ssh&ch research supported by ris leads to better understanding of who we are and how society works – but how to measure this and what exactly is the contribution by the ri? • uptake by policymakers and media is a clear signal – but ri role largely invisible, as they would normally refer to scientific articles and publications in the best case, but not to their sources • for the assessment of the impact that we make on society as a whole we are largely dependent on “circumstantial evidence”, such as reputation. • in this context the dariah impactomatrix is a rich source of inspiration to identify factors that can help boosting the impact, and criteria to (indirectly) measure the effects. clarin concluding remarks • measuring our own efforts to have an impact is easy, measuring the result is hard. • european ssh&ch is diverse, and not focused on specific common targets such as putting a man on the moon, using nuclear fusion to produce electricity or solving the cancer problem. this makes notions such as progress and impact hard to define. • it is my feeling that disciplines are much better off if they are backed by a generally acknowledged societal threat or disaster, such as pollution, energy crisis, ageing population or climate change • i still hope that europe will one day see that social climate change is as much of a threat as the other ones (as the migration problem clearly illustrates) and that a coordinated europe-wide ssh&ch research effort is needed to address it • ris are in an excellent position to play a role in this and should think about what they could do to facilitate this clarin citizen viewpoints on energy policy policy sciences ( ) - elsevier scientific p u b l i s h i n g c o m p a n y , a m s t e r d a m - printed in the n e t h e r i a n d s citizen viewpoints on energy policy* r o n a l d d . b r u n n e r and w e s t o n e. v i v i a n institute o f public poti~ ' studies. the university o f michigan, ann arbor, michigan a b s t r a c t t h i s e x p l o r a t i o n of citizen v i e w p o i n t s o n e n e r g y policy u s e s a c l u s t e r i n g t e c h n i q u e to analyze q - s o r t s o b t a i n e d f r o m a diverse n a t i o n a l s a m p l e in april . t h e results i n d i c a t e a n a p p r o x i m a t e c o n s e n s u s . t h e p r e d o m i n a n t t h e m e s in t h e core v i e w p o i n t a n d t h r e e p e r i p h e r a l v a r i a t i o n s are resistance to e n e r g y price increases a n d c o n c e r n for public health, safety, a n d t h e e n v i r o n m e n t , p a r t i c u l a r l y in c o n n e c t i o n w i t h n u c l e a r p o w e r plants. t h e r e is also w i d e s p r e a d d i s t r u s t o f t h e oil a n d gas i n d u s t r y , local utilities, t h e p r e s i d e n t , g o v e r n m e n t generally, a n d e n e r g y experts, coupled with disbelief, d i s t r u s t , disaffection, a n d u n d e r t o n e s o f m o r a l o u t r a g e . t h e e x i s t e n c e o f this a p p r o x i m a t e c o n s e n s u s is less s u r p r i s i n g t h a n the a b s e n c e o f s h a r e d v i e w p o i n t s t h a t a r e i n d e p e n d e n t or o p p o s e d to it. i n d i v i d u a l i n t e r p r e t a t i o n s o f t h e m a i n t h e m e s are e x p l o r e d t h r o u g h u n s t r u c t u r e d , follow-up interviews with t h e best r e p r e s e n t a t i v e s o f t h e core viewpoint. t h e e v o l u t i o n o f s h a r e d v i e w p o i n t s h a s been s h a p e d by specific e v e n t s s u c h as t h r e e mile i s l a n d a n d by r e c u r r i n g events, particularly c h r o n i c energy price increases a n d i n t e r m i t t e n t s h o r t a g e s , a n d t h e o n g o i n g n a t i o n a l d e b a t e o n e n e r g y policy. i n o u r i n t e r p r e t a t i o n , t h e social t e n s i o n a n d p e r s o n a l insecurities a c c u m u l a t e d as a result o f t h e energy s i t u a t i o n are potentially destabilizing. however, the potential for rapid c h a n g e in citizen v i e w p o i n t s h a s so f a r been blocked by p e r c e p t u a l a n d political rigidities t h a t u n d e r l i e a n a p p r o x i m a t e s t a l e m a t e in w a s h i n g t o n . t h e c o n c l u d i n g s e c t i o n p r e s e n t s s o m e s u g g e s t i o n s for d e a l i n g with t h e p e r c e p t u a l , political, a n d moral a s p e c t s o f t h e s i t u a t i o n . i. introduction o u r inability to realize s a t i s f a c t o r y p r o g r e s s t o w a r d a s u s t a i n a b l e energy f u t u r e has been a t t r i b u t e d to the energy policy process and, often indirectly, to o u r institutions o f g o v e r n m e n t , law a n d politics. f r o m one perspective, the political s y s t e m enables special interests a n d a r e c a l c i t r a n t public to f r u s t r a t e the a d o p t i o n o f r a t i o n a l a n d c o m p r e h e n s i v e policies d e v e l o p e d by e x p e r t s in the federal g o v e r n m e n t . f r o m * w e w o u l d like to t h a n k g e r a l d a. c o l e for his c o n t r i b u t i o n s to t h e initial p h a s e s o f this s t u d y , a n d t h e u n i v e r s i t y o f m i c h i g a n for f i n a n c i a l s u p p o r t . a n earlier v e r s i o n o f t h i s p a p e r was p r e s e n t e d at t h e t h a n n u a l m e e t i n g o f t h e a m e r i c a n n u c l e a r society, j u n e , , in a t l a n t a . - / / - / $ . � elsevier scientific p u b l i s h i n g c o m p a n y a n o t h e r , the political s y s t e m enables the public a n d the federal g o v e r n m e n t to inhibit the d e v e l o p m e n t o f efficient m a r k e t solutions. a closer l o o k at citizen viewpoints on energy policy, a n d their role in the policy process, sheds s o m e light on these diagnoses. a citizen's v i e w p o i n t on a public issue such as energy policy is a n evolving p a t t e r n a m o n g an indefinite n u m b e r o f attitudes a n d opinions. direct or m e d i a t e d e x p e r i e n c e m a y induce shifts in the direction or intensity o f a few o f these p r e d i s p o s i t i o n s relative to others, a n d t h e r e b y create stresses t o w a r d a d j u s t m e n t elsewhere in the pattern. e a c h c h a n g e in the overall p a t t e r n redefines the m e a n i n g s o f the p a r t i c u l a r attitudes and opinions included within it. w h i c h p r e d i s p o s i t i o n s c h a n g e significantly in t e r m s o f intensity, direction, or m e a n i n g d e p e n d s u p o n m a n y factors? at one e x t r e m e are the primitive needs o f the p e r s o n a l i t y left o v e r f r o m earliest childhood. a t the o t h e r are events o n a global scale, such as changes in the p r o d u c t i o n a n d price o f m i d d l e e a s t e r n crude oil. w h a t results f r o m the i n t e r p l a y o f such factors is a citizen's v i e w p o i n t t h a t is u l t i m a t e l y unique, but which is similar in some degree to the viewpoints o f others. t h e f u n c t i o n o f p r o m o t i o n a l politics is to intensify, c o o r d i n a t e , a n d redefine certain predispositions on a selective basis, in o r d e r to mobilize support. t h e extent to which p r o m o t i o n a l efforts succeed or fail, given c o m p e t i n g efforts a n d u n p l a n n e d events, is a m a t t e r o f o v e r r i d i n g i m p o r t a n c e f o r public policy, as the diagnoses s k e t c h e d a b o v e suggest: w i d e s p r e a d public o p p o s i t i o n m a y r e n d e r the efforts o f policy planners politically infeasible or (if a d o p t e d ) ineffective. o u r p u r p o s e here is to e x p l o r e citizen v i e w p o i n t s a n d their i n t e r a c t i o n with elite perspectives in the energy policy process; a n d to suggest the need to r e t h i n k energy policy p l a n n i n g as a m e a n s o f c o p i n g with subjective differences. f o r this study, in april we asked citizens nationwide to express their v i e w p o i n t s on e n e r g y policy. t h r o u g h a p r o c e d u r e k n o w n as q - t e c h n i q u e [ ], each s o r t e d a s a m p l e o f s t a t e m e n t s culled f r o m public discourse on the issue a n d selected a c c o r d i n g to a t h e o r e t i c a l f r a m e w o r k [ ]. i n c o n t r a s t t o the m o r e f a m i l i a r s a m p l e surveys, this t e c h n i q u e is relatively specialized to the identification o f s h a r e d viewpoints, and to qualitative questions o f intensity, direction, and m e a n i n g in each o f them. w e used cluster analysis [ ], a f o r m o f n u m e r i c a l t a x o n o m y , to analyze the data. in a d d i t i o n , we c o n d u c t e d follow-up, u n s t r u c t u r e d interviews with the best represen- tatives o f these viewpoints in j u n e . t h e results reveal only one basic, s h a r e d viewpoint on energy policy a m o n g these r e s p o n d e n t s , a l t h o u g h certain v a r i a t i o n s are distinguishable. as in a n y a p p r o x i m a t e consensus, individual i n t e r p r e t a t i o n s o f the m a i n p r o p o s i t i o n s differ in s o m e ways. t h e p r e d o m i n a n t t h e m e s are resistance to energy price increases a n d c o n c e r n f o r public health, safety, a n d the e n v i r o n m e n t , particularly in c o n n e c t i o n with nuclear p o w e r plants. t h e r e is also widespread distrust o f the oil a n d gas industry, local utilities, the president, a n d energy experts, c o u p l e d with disbelief, disorientation, disaffection, a n d u n d e r t o n e s o f m o r a l outrage. t h e existence o f this a p p r o x i m a t e consensus is less surprising t h a n the absence o f shared viewpoints t h a t are independent or o p p o s e d to it. t h e e v o l u t i o n of shared viewpoints on energy policy has been shaped by specific events such as the incident at t h r e e mile island and by recurring events, particularly chronic energy price increases and i n t e r m i t t e n t shortages, and the ongoing national energy policy debate. in o u r interpretation, the social tension and personal insecurities a c c u m u l a t e d as a result of the energy situation are potentially destabilizing. however, the potential for rapid change in citizen viewpoints has so far been blocked by perceptual and political rigidities that underlie an a p p r o x i m a t e stalemate in washington. t h e concluding section presents some suggestions for dealing with the perceptual, political, and moral aspects of the situation. ii. m e t h o d s f o r those readers unfamiliar with the methods used here, a digression is in order. o t h e r readers are encouraged to proceed to the next section. q-techniques, as we have noted, are a p p r o p r i a t e for discovering the n u m b e r and c o n t e n t of shared viewpoints. a shared viewpoint is a p a t t e r n o f m an y attitudes and opinions organized into a c o h e r e n t whole by like-minded individuals. t h r o u g h the university s u r v e y research c e n t e r we c o n t a c t e d a diverse (but not r a n d o m ) set o f respondents. each r e s p o n d e n t was asked to model his or her viewpoint on energy by sorting statements, each typed on a separate card, acco rd i n g to relative intensity and direction ( a g r e e m e n t or disagreement). m o r e specifically, each r e s p o n d e n t did a preliminary sorting of the statements by agreement, disagreement, or relative indifference. t h e few statements agreed with most intensely were t h en placed at the + e x t r e m e of a c o n t i n u u m ; the few statements disagreed with most intensely were placed at the - extreme; and sorting c o n t i n u e d in this manner, alternating f r o m one side to the other, until all of the remaining statements were located with respect to each other. t h e result is a q-sort, in which intensity and d i r e c t i o n are given directly by the respondent. meanings i m p u t e d to any particular st at em en t by a r e s p o n d e n t can be inferred f r o m the overall pattern. f r o m the q-sort p r o v i d e d by each r e s p o n d e n t we f o r m e d the m at ri x o f distances between each pair of respondents i a n d j . distance was defined as di, j = - ri,j, where ri, j is the p r o d u c t - m o m e n t c o r r e l a t i o n between their q-sorts with each statement weighted equally. t h e average linkage m e t h o d was used to f o r m clusters o f r e s p o n d e n t s who share in some degree the same viewpoint. in this p ro ced u re, each res pondent is initially construed as a single-member cluster. t h e n the two clusters (or res pondents) s e p a r a t e d by the smallest distance are j o i n e d to f o r m a t w o - m e m b e r cluster. in the next and all succeeding operations, the two clusters separated by the smallest average distances between all pairs of their m em b ers are joined. in the final operation, all respondents are joined in one cluster. t h e n o n - r a n d o m sampling p r o c e d u r e entailed s o c i o d e m o g r a p h i c quotas assigned to each of seventeen interviewers. it does not permit estimates o f the proportion of the national population that holds a particular opinion or viewpoint. together with the clustering techniques, however, it is sufficiently sensitive to signal the existence of any shared viewpoint in the population represented by several or more o f the respondents. diversity rather than randomness is the most appropriate sampling objective for this purpose. iii. an approximate consensus the organization of viewpoints is summarized in fig. i. each point along the horizontal axis at the bottom of the figure represents one o f the respondents. thus i step i cluster ~ ~ dist x . x.i . x. . x. . all rs i i i.ii i q i i g l t v v v v ~ v f , v i i i respondents fig. . organization of viewpoints. the width o f a cluster reflects the n u m b e r of r e s p o n d e n t s included within it. t h e vertical axis is scaled in steps, which indicate the point in the clustering p r o c e d u r e at which the v a r i o u s clusters f o r m e d . t h e steps are n u m b e r e d f r o m to , b o t t o m to top, in reverse o f the sequence o f o p e r a t i o n s . t h r o u g h this c o n v e n t i o n , the step n u m b e r s indicate the n u m b e r o f clusters r e m a i n i n g at each point in the sequence. f r o m the start o f the p r o c e d u r e to the conclusion, the clusters b e c o m e increasingly h e t e r o g e n e o u s with respect to the v i e w p o i n t s o f the r e s p o n d e n t s included within them. t h e table in fig. gives the a v e r a g e distances between all pairs o f m e m b e r s of the two clusters j o i n e d to f o r m x, x . l , x. , x. , a n d the final cluster, a l o n g with the step at which the c o m p o n e n t clusters j o i n e d a n d cluster size. f i g u r e indicates t h a t there exists only one basic, s h a r e d v i e w p o i n t a m o n g these r e s p o n d e n t s with respect to the s t a t e m e n t s . t h e r e s p o n d e n t s in cluster x are the core r e p r e s e n t a t i v e s of this viewpoint. t h e r e s p o n d e n t s in the o t h e r distinguishable clusters - x. , x. , a n d x. - s h a r e related b u t p e r i p h e r a l viewpoints. t h e v i e w p o i n t s o f the o t h e r r e s p o n d e n t s are idiosyncratic. t h e key point is t h a t no s h a r e d viewpoint i n d e p e n d e n t o f the core v i e w p o i n t or o p p o s e d to it emerged f r o m the data. n o o t h e r cluster rivals the core cluster x in t e r m s o f the h o m o g e n e i t y a n d the n u m b e r o f r e s p o n d e n t viewpoints included within it. it is c o m p r i s e d o f respondents, o v e r a q u a r t e r o f the total. at the s a m e level o f h o m o g e n e i t y , only one o f the o t h e r clusters r e m a i n i n g at this step (a subset o f x. ) includes as m a n y as six r e s p o n d e n t viewpoints. t h e others include f o u r or less. m o r e o v e r , the r e m a i n i n g distinguishable clusters c o m p r i s i n g at least % o f the r e s p o n d e n t s merge with x o n the basis o f relatively small a v e r a g e distances. consider, for e x a m p l e , the worst case. a t step where the x. cluster (n ---- ) merges with the a u g m e n t e d core cluster (n = ), the distance m e a s u r e indicates t h a t the a v e r a g e c o r r e l a t i o n a m o n g the x = pairs o f r e s p o n d e n t v i e w p o i n t s b e t w e e n the t w o clusters is . . t h e v i e w p o i n t s included in x. are, o n average, m o r e similar to the v i e w p o i n t s in the a u g m e n t e d core cluster t h a n to the relatively idiosyncratic viewpoints in the other clusters c o m p r i s e d o f r e s p o n d e n t s r e m a i n i n g at this step. t h e latter j o i n the a u g m e n t e d core cluster at large distances. t h e c o n c l u s i o n t h a t there exists only one s h a r e d viewpoint, o r g a n i z e d into core and p e r i p h e r a l v a r i a t i o n s , is s u p p o r t e d by the p a t t e r n o f c o r r e l a t i o n s a m o n g cluster profiles. a cluster profile is the a v e r a g e score ( o r rank) o f each of the s t a t e m e n t s assigned by m e m b e r s o f the cluster. it c a n be i n t e r p r e t e d as the q - s o r t t h a t would have been p r o v i d e d by a n " i d e a l " or " p e r f e c t " r e p r e s e n t a t i v e o f the s h a r e d viewpoint. t h e a v e r a g i n g p r o c e d u r e used to f o r m cluster profiles suppresses the dispersion o f s t a t e m e n t scores ( o r ranks) a m o n g cluster m e m b e r s . i f the s h a r e d viewpoints were i n d e p e n d e n t , the c o r r e l a t i o n between their cluster profiles w o u l d be a p p r o x i m a t e l y zero. i f the s h a r e d viewpoints were o p p o s e d or polarized, the c o r r e l a t i o n between their cluster profiles w o u l d be negative. as s h o w n in t a b l e the c o r r e l a t i o n s between the profiles are consistently high a n d positive. x is not only the m o s t h o m o g e n e o u s cluster o f r e s p o n d e n t s , as we h a v e seen; its profile is also highly c o r r e l a t e d with the a v e r a g e ] ' a b l e l correlations a m o n g cluster profiles clusters x x. x. x. all rs x . x.l . . x. . . . x. . . . . all rs . . . . . viewpoint in the peripheral clusters and with the average viewpoint in the sample as a whole. before turning to the content o f core and peripheral viewpoints, it is worthwhile to examine alternative explanations. the structure o f the data may not be the best explanation for the emergence of only one shared viewpoint in several variations. one alternative explanation is that the organization o f viewpoints summarized in fig. is an artifact of the average linkage method. the best test of this possibility is to apply the complete linkage (or farthest neighbor) m e t h o d to the same data. under this method: when two clusters join, their similarity is that existing between the farthest pair of members, one in each cluster. the method will generally lead to tight, hyperspherical, discrete clusters that join only with difficulty and at relative low overall similarity values [ ]. with these d a t a the complete linkage m e t h o d does p r o d u c e relatively discrete clusters that join late in the procedure at the lower-numbered steps. however, the classifica- tion o f respondents p r o d u c e d by this m e t h o d is similar to the classification p r o d u c e d by the average linkage m e t h o d for these data. a n d the cluster profiles reveal that the statements having rather high positive and negative mean scores are the same statements that a n c h o r the cluster profiles p r o d u c e d by the average linkage method. i n other words, profiles of the clusters generated by the two methods are quite similar. a n o t h e r alternative e x p l a n a t i o n is that the o r g a n i z a t i o n o f viewpoints summarized in fig. is an artifact o f the particular opinions included in the sample o f statements. more specifically, the possibility exists that the sample of statements is biased in the direction o f highly consensual statements. there are inherent difficulties in testing this alternative because the universe of possible statements is essentially u n b o u n d e d , and because there is no n o n a r b i t r a r y s t a n d a r d to distinguish a biased f r o m an unbiased sample. however, we applied the average linkage m e t h o d to the data set that excluded the six statements having the highest mean scores (positive or negative direction) in the cluster o f all respondents. the classification o f respondents and the organization o f viewpoints is quite similar to that summarized in fig. . i n short, deleting the most consensual statements f r o m the sample of statements makes little difference. a third a l t e r n a t i v e e x p l a n a t i o n is t h a t the o r g a n i z a t i o n o f v i e w p o i n t s is a n artifact o f the set o f r e s p o n d e n t s interviewed f o r this study. i n the absence o f o t h e r collections o f r e s p o n d e n t s interviewed in the s a m e way at the s a m e time, little can be said conclusively. i n t e r v i e w e r s were instructed to select r e s p o n d e n t s a c c o r d i n g to diversity o f s o c i o d e m o g r a p h i c characteristics in o r d e r to m i n i m i z e the possibility t h a t a n y significant v i e w p o i n t existing in the p o p u l a t i o n would go undetected. t h e p r o c e d u r e s used here are sufficiently sensitive to detect the existence o f a n i n d e p e n d e n t or o p p o s e d v i e w p o i n t if only several r e p r e s e n t a t i v e s o f the v i e w p o i n t are included [ ]. t h e o r g a n i z a t i o n o f v i e w p o i n t s t h a t emerges f r o m these d a t a represents an a p p r o x i m a t e c o n s e n s u s on the intensity a n d d i r e c t i o n of a n u m b e r o f e n e r g y - r e l a t e d attitudes a n d opinions, but not necessarily o n their meanings. i n this instance, as in legislatures, m a r k e t s , and o t h e r political a n d social settings, a g r e e m e n t a m o n g a n u m b e r o f p e o p l e o n a set o f p r o p o s i t i o n s m a s k s a v a r i e t y o f differences a m o n g individual i n t e r p r e t a t i o n s o f the p r o p o s i t i o n s a n d the reasons f o r a c c e p t i n g them. u n d e r these circumstances, i n t e r p r e t a t i o n reflects one's o b s e r v a t i o n a l s t a n d p o i n t , a n d no single i n t e r p r e t a t i o n , including the i n t e r p r e t a t i o n of the analyst, is exhaustive. iv. the shared viewpoints: core and periphery recall t h a t a cluster profile is f o r m e d by a v e r a g i n g the scores ( o r ranks) assigned to e a c h s t a t e m e n t by m e m b e r s o f the cluster. as a result o f this o p e r a t i o n , the s t a t e m e n t s t h a t are m a t t e r s o f i m p o r t a n c e and consensus t u r n out to h a v e the m o s t e x t r e m e scores, t e n d i n g t o w a r d + a n d . t h e s t a t e m e n t s h a v i n g the m o s t e x t r e m e m e a n scores ( g r e a t e r t h a n . ) in the core v i e w p o i n t profile are r e p r o d u c e d in t a b l e . t h e o t h e r s t a t e m e n t s , with m e a n s t e n d i n g t o w a r d zero, are either relatively insignificant o r relatively c o n t r o v e r s i a l a m o n g m e m b e r s o f the core cluster. as we have a l r e a d y suggested, i n t e r p r e t a t i o n o f this s h a r e d v i e w p o i n t ( o r a n y other) is by no m e a n s s t r a i g h t f o r w a r d . o n the one hand, a n u m b e r o f plausible t h e m e s m a y be w o v e n a m o n g the v a r i o u s c o m b i n a t i o n s o f t w o or m o r e s t a t e m e n t s . o n the other, each s t a t e m e n t m a y h a v e a n u m b e r o f c o n n o t a t i o n s d e p e n d i n g u p o n the c o n t e x t o f o t h e r s t a t e m e n t s with which it is associated. t h e process is inherently open-ended. h e r e we begin the process by starting with the manifest c o n t e n t o f the viewpoint profile, a n d in p a r t i c u l a r with the s t a t e m e n t s h a v i n g the highest degree o f significance a n d consensus. c o r e viewpoint r e s p o n d e n t s in the core cluster object m o s t strongly t o the l o c a t i o n o f new nuclear p o w e r plants in the areas where they live ( .__a, - . ). h o w e v e r , there is very little consensus on the b r o a d e r issues o f w h e t h e r the n a t i o n needs m o r e nuclear p o w e r or w h e t h e r f e d e r a l subsidies f o r n u c l e a r p o w e r are a p p r o p r i a t e (see s t a t e m e n t s a n d t a b l e cluster x profile: t h e m o s t significant and c o n s e n s u a l s t a t e m e n t s * m o s t disagree m o s t agree . h a v e no objections to the location o f a new n u c l e a r power p l a n t in the a r e a where i live. (- . i~ - . , - . , • ..~ we s h o u l d accept a d d i t i o n a l risks to public h e a l t h a n d safety in order to deal with t h e energy crisis. (- . _..~,- . ,- . , . ) . c o n s u m e r prices o f gasoline, n a t u r a l gas, fuel oil a n d electricity are t o o low. (- . .,..~, . , . , - . ) . t h e oil a n d gas c o m p a n i e s deserve t h e t r u s t of people like me. (- . ..__ z, . , - . , . ) . o v e r t h e n e x t t w e n t y years, solar e n e r g y j u s t c a n ' t m a k e m u c h difference in m e e t i n g t h e n a t i o n ' s energy needs. ( - . .._. d, . , - . , - . ) . w o n ' t cut back on m y energy u s e until o t h e r s m a k e t h e s a m e sacrifice. ( . _.__ z - . , - . , - . ) .,.. a a n increase in gas a n d electric bills m e a n s m o r e h a r d s h i p for t h e p o o r a n d t h o s e o n fixed incomes. ( + . , + . , + , , + . ) . n o t even t h e e x p e r t s k n o w how to safely dispose o f radioactive wastes f r o m nuclear power plants. (+ . .__. z + . , + . , + . ) .. a e n e r g y research a n d d e v e l o p m e n t s h o u l d e m p h a s i z e renewable energy sources like solar energy. (+ . __= + . , + . , + . ) . w e s h o u l d do w h a t e v e r we c a n to m a k e o u r j'obs a n d i n c o m e s less d e p e n d e n t on foreign oil. (+ . ..._., + . , + . , -t- . ) . oil a n d n a t u r a l gas h a v e been withheld f r o m the m a r k e t to force c o n s u m e r price increases. (+ . _... d, + . , + . , + . ) . w a n t better i n f o r m a t i o n a b o u t h o w t h e energy crisis affects me a n d m y c o m m u n i t y , a n d w h a t we can do a b o u t it. ( - . .......,,-t- . , + . , + . ) . i d o n ' t k n o w w h o m o r w h a t to believe a b o u t t h e energy situation� (+ . __,+ . , . , . ) * t h e figures in p a r e n t h e s e s a r e cluster m e a n s for clusters x. x. l, x. , a n d x. , respectively. m e a n s for cluster x are u n d e r s c o r e d . in the a p p e n d i x ) . o p p o s i t i o n to the siting o f nuclear p o w e r plants in n e a r b y areas a p p e a r s to be the focal p o i n t o f health a n d safety concerns. t h e s e r e s p o n d e n t s reject the p r o p o s i t i o n t h a t we should accept a d d i t i o n a l risks to public health a n d safety in o r d e r to deal with the energy crisis ( , . ); a n d they believe t h a t not even the experts k n o w how to safely dispose o f radioactive wastes f r o m nuclear p o w e r plants ( , + . ). t h e s e r e s p o n d e n t s express s u b s t a n t i a l s u p p o r t f o r solar energy. the}' agree t h a t renewable energy sources including solar should be e m p h a s i z e d in energy research a n d d e v e l o p m e n t ( _ + . ); and they reject the p r o p o s i t i o n that solar energy c a n n o t m a k e m u c h difference in m e e t i n g the n a t i o n ' s energy needs over the next t w e n t y years ( _ - . ). o t h e r sources o f s u p p l y are less significant, a l t h o u g h m o d e s t s u p p o r t exists for increasing the d o m e s t i c p r o d u c t i o n o f oil a n d gas a n d for the c o m m e r c i a l i z a t i o n o f synthetic fuels ( a p p . , ). t h e s e views on s u p p l y m a y be related to expressed s u p p o r t for the goal of reducing the d e p e n d e n c e of o u r j o b s a n d i n c o m e s on foreign oil ( , + . ). while the e m p h a s i s a p p e a r s to be on e n s u r i n g supplies o f energy (subject to e n v i r o n m e n t a l constraints), there are also signs of s u p p o r t for reducing d e m a n d . t h e s e r e s p o n d e n t s reject n o n c o n s e r v a t i o n by others as a r e a s o n for not c o n s e r v i n g themselves ( , - . ); a n d the}, express a m o d e s t degree of s u p p o r t f o r the goal of n u r t u r i n g a r e s o u r c e - c o n s e r v i n g ethic ( a p p . _ .). e n e r g y prices are significant p r i m a r i l y in t e r m s o f the hardships the}' i m p o s e o n the p o o r a n d those on fixed i n c o m e s ( ._._, + . ). s o m e o f the r e s p o n d e n t s m a y include t h e m s e l v e s a m o n g those w h o h a v e e x p e r i e n c e d such e c o n o m i c hardships, even if they are not p o o r or living on fixed incomes. t h e y reject the p r o p o s i t i o n t h a t c o n s u m e r prices o f energy are t o o low ( , - . ), a p r o p o s i t i o n t h a t is the c o r n e r s t o n e of energy policy in the c a r t e r a d m i n i s t r a t i o n . t h e r e is no s y s t e m a t i c s u p p o r t f o r either the policy o f oil a n d gas price d e c o n t r o l ; o r the e x p e c t a t i o n t h a t d e c o n t r o l will lead to fair a n d efficient a l l o c a t i o n t h r o u g h the m a r k e t ; or the belief t h a t energy price increases are necessary to ensure a d e q u a t e supplies ( a p p . , , ). all o f these are a m o n g the j u s t i f i c a t i o n s for price increases in w a s h i n g t o n . c o n s u m e r price increases are i n t e r p r e t e d in p a r t as the result o f oil a n d gas being withheld f r o m the m a r k e t ( __ + . ). t h e v i e w p o i n t is also m a r k e d by w i d e s p r e a d distrust: t h o s e who share it disagree on a v e r a g e t h a t the oil a n d gas c o m p a n i e s deserve the t r u s t o f " p e o p l e like me" ( _.__, - . ); t h a t the local gas a n d electric c o m p a n i e s will d o w h a t is best f o r " a l l o f us"; a n d to a lesser e x t e n t t h a t " p e o p l e like me" s h o u l d trust the president to find a solution to the energy crisis. m o r e o v e r , they believe t h a t p e o p l e w h o direct their hostility t o w a r d business or g o v e r n m e n t a r e n o t just l o o k i n g f o r s c a p e g o a t s . o n the positive side is a m o d e s t degree o f s u p p o r t for o r g a n i z a t i o n s t h a t w o r k f o r c o n s u m e r interests in energy issues ( a p p . , , , ). r e l a t e d to these m a n i f e s t a t i o n s o f distrust is a lack o f credibility a n d a d e m a n d f o r b e t t e r i n f o r m a t i o n . m o s t o f these r e s p o n d e n t s do not k n o w w h o or w h a t to believe a b o u t the energy s i t u a t i o n ( _..z + . ). t h e r e is no systematic s u p p o r t for a g r e a t e r effort by the federal g o v e r n m e n t to sell its energy policy p r o p o s a l s to the public, or f o r the idea t h a t the t r u t h a b o u t the energy crisis is difficult to convey to the p u b l i c ( a p p . , ). but these r e s p o n d e n t s d o w a n t b e t t e r i n f o r m a t i o n a b o u t how the energy crisis affects t h e m a n d their c o m m u n i t i e s , a n d w h a t they can d o a b o u t it ( __ z + . ). a g e n e r a l p a t t e r n is a p p a r e n t in the core v i e w p o i n t profile. it is a selective e m p h a s i s on those aspects o f the energy s i t u a t i o n t h a t p e r t a i n to the i m m e d i a t e c i r c u m s t a n c e s o f the r e s p o n d e n t s o r others like t h e m . note, f o r e x a m p l e , t h a t the significance o f energy price increases, nuclear power, a n d o t h e r e n e r g y issues is c o n s t r u e d p r i m a r i l y in terms o f i m p a c t s o n individual citizens a n d the areas where they live. t h e s e i m p a c t s include health a n d safety, e c o n o m i c hardships, j o b a n d i n c o m e security, distrust, disorienta- tion, a n d a sense o f unfair t r e a t m e n t . a t the s a m e time, the n a t i o n a l i m p l i c a t i o n s o f these issues are generally discounted. w h e t h e r the n a t i o n needs energy price increases or nuclear power, a n d the possible t a b l e p e r i p h e r a l c l u s t e r p r o f i l e s : d i f f e r e n c e s i n p r i o r i t i e s c o r e profile p e r i p h e r a l profiles x r a n k st. mean x. x. x. st. m e a n st. m e a n st. m e a n + . * + . " + . + . + . + . l * + . + . + . * + . + . + . + . + . + . * + . + . + . + . * + . + . * + . + . + . + . + . * + . * + . + . " - . + . - + . + . + . - . - . * - . - . - . * . * . - . * - . * - . . - . . - . . - . - . - . . : - . " . - . - . * . . - . * - . . - . * i n d i c a t e s t h a t the s t a t e m e n t is n o t a m o n g t h o s e s t a t e m e n t s in the x profile that have a mean gr e a te r t h a n . . reasons why, are either relatively insignificant or are controversial. t h e s e n a t i o n a l implications are o f course r e m o t e with respect to individual experience. t h e r e is a t e n d e n c y to discount the o b s e r v a t i o n s a n d i n t e r p r e t a t i o n s circulated by g o v e r n m e n t and business, which are not generally perceived as t r u s t w o r t h y sources o n the n a t i o n a l interest in energy policy. p e o p l e a p p e a r to rely on their o w n personal o b s e r v a t i o n s and interpretations [ ]. i n short, the energy s i t u a t i o n f r o m the v i e w p o i n t of these citizens is quite different f r o m the one pictured in c o r p o r a t e h e a d q u a r t e r s or in w a s h i n g t o n . we shall r e t u r n to this p a t t e r n in a later section. peripheral viewpoints differences in priorities a m o n g the r e p r e s e n t a t i v e s of the p e r i p h e r a l v i e w p o i n t s are s u m m a r i z e d by s t a t e m e n t numbers, a n d means in t a b l e . t a b l e includes all s t a t e m e n t s in the three p e r i p h e r a l v i e w p o i n t s h a v i n g m e a n s g r e a t e r than] . ]. m o s t of these s t a t e m e n t s are also a m o n g the m o s t significant s t a t e m e n t s in the core viewpoint. t h e e x c e p t i o n s are n o t e d with a n asterisk. s t a t e m e n t s referred to in t a b l e are r e p r o d u c e d in the a p p e n d i x . t h e x. v i e w p o i n t is m a r k e d by a g r e a t e r e m p h a s i s on n a t i o n a l energy policy, but the direction of o p i n i o n is generally the s a m e as in the core viewpoint. t h e people w h o share this p e r i p h e r a l v i e w p o i n t s u p p o r t a windfall profits t a x a n d h o r i z o n t a l divestiture o f the m a j o r oil c o m p a n i e s ( , ); and they reject d e c o n t r o l o f oil and gas prices, a n d the s u p p o r t i n g e x p e c t a t i o n t h a t d e c o n t r o l would lead to fair a n d efficient a l l o c a t i o n t h r o u g h the m a r k e t ( , ). h a r d s h i p s created by energy price increases a p p e a r to be a m o n g the reasons ( ). c o n c e r n for public health a n d safety is also f o u n d in this v i e w p o i n t ( , ), but it is not focused on nuclear p o w e r ( ). d i s t r u s t is heightened in this viewpoint, but the focus is shifted p r i m a r i l y to the president, the experts, a n d local utilities ( , , a n d ) . t h e s e r e s p o n d e n t s agree t h a t " p e o p l e like m e " are i g n o r e d when big business a n d big g o v e r n m e n t m a k e energy policy in w a s h i n g t o n (, ). t h e general i m p r e s s i o n is t h a t in this viewpoint, as o p p o s e d to the core v i e w p o i n t , distrust is e x p r e s s e d in o p p o s i t i o n to federal policies t h a t would p e r m i t or i n c r e a s e " m a r k e t " c o n t r o l o v e r energy at the perceived expense o f the public. t h e x. v i e w p o i n t is m a r k e d by a n e n h a n c e d c o n c e r n f o r e n v i r o n m e n t a l p r o t e c t i o n ( , , a n d ) and energy c o n s e r v a t i o n . t h e s e r e s p o n d e n t s strongly e n d o r s e the goal o f n u r t u r i n g a r e s o u r c e - c o n s e r v i n g ethic ( ), o p p o s e the p r o m o t i o n o f energy c o n s u m p t i o n t h r o u g h advertising ( ), a n d reject one o f the r a t i o n a l i z a t i o n s for not c u t t i n g b a c k on p e r s o n a l energy c o n s u m p t i o n ( ). c o n c e r n s for e n v i r o n m e n t a l p r o t e c t i o n a n d c o n s e r v a t i o n a p p e a r to be focused in a rejection o f nuclear power, b o t h in the areas where the r e s p o n d e n t s live ( ) and as a n energy alternative s u p p o r t e d by the federal g o v e r n m e n t ( ). t h e y strongly agree t h a t the n a t i o n does have alternatives to increased d e p e n d e n c e on nuclear p o w e r ( ). t h e s e t h e m e s can be discerned in the core viewpoint, but they are e n h a n c e d a n d generalized here. t h e m a j o r difference between the core v i e w p o i n t and the x. v i e w p o i n t is that the latter shows little c o n c e r n for e n e r g y prices ( ). incidentally, representatives o f b o t h the x. a n d x. viewpoints reject the t h r e a t or use o f military force if a n energy crisis is i m p o s e d on t h e m ( ). t h e x. viewpoint is less h o m o g e n e o u s t h a n the others. it is m a r k e d by the strongest s u p p o r t f o r b o t h s o l a r energy a n d f o r nuclear power, and by the least s u p p o r t for e n v i r o n m e n t a l p r o t e c t i o n . i n the case o f nuclear power, there is little consensus on the location o f a nuclear p o w e r plant in the areas where these r e s p o n d e n t s live ( ), but they d o believe t h a t the n a t i o n must increase its d e p e n d e n c e on nuclear p o w e r ( ), a n d t h e r e is s o m e s u p p o r t f o r federal subsidies ( ). t h e m o s t i m p o r t a n t c o n c e r n a p p e a r s to he a n x i e t y o v e r the w o r l d e n e r g y s i t u a t i o n ( ), a n d its t h r e a t to their j o b s a n d incomes. t h i s t h e m e is a p p a r e n t in the core v i e w p o i n t , but m a g n i f i e d in significance here. sociodemographic characteristics t h e s o c i o d e m o g r a p h i c characteristics o f the r e s p o n d e n t s , including the others (unclassified), are s u m m a r i z e d in t a b l e . these distributions refer to the set o f r e s p o n d e n t s a n d not to the p o p u l a t i o n at large. i n general, t h e r e are few differences a m o n g the cluster m e m b e r s . i n t e r m s o f age cohorts, the d i s t r i b u t i o n o f cluster m e m b e r s d e p a r t s only slightly f r o m the distribution e x p e c t e d o n the basis o f relative cluster size. t h e d i s t r i b u t i o n by sex c o n f o r m s even m o r e closely to the e x p e c t e d distribution. ( o t h e r studies h a v e s h o w n a t e n d e n c y for w o m e n to prefer a n t i - n u c l e a r a n d p r o - e n v i r o n m e n t positions o v e r men. these positions are m o s t a p p a r e n t in the core cluster x a n d the p e r i p h e r a l cluster x. , as we h a v e seen.) at least one r e s p o n d e n t f r o m e a c h o f the b r o a d r e g i o n a l classifications is a m e m b e r o f each o f the clusters. i f regional differences are i m p o r t a n t in the p o p u l a t i o n , such differences are not a p p a r e n t a m o n g these respondents. d i f f e r e n c e s d o a p p e a r , however, with respect to education. t h e m e m b e r s o f the x. cluster, the m o s t s t r o n g l y a n t i - n u c l e a r a n d p r o - e n v i r o n m e n t , are the m o s t highly educated. f i v e o f the seven h a v e d o n e g r a d u a t e work, a n d n o n e have only years o f e d u c a t i o n or less. t h e m e m b e r s o f the core cluster h a v e the next m o s t education, and the m e m b e r s o f the x . i a n d x. clusters have the least. t h e r e s p o n d e n t s w h o hold the m o r e idiosyncratic viewpoints, a n d are t h e r e f o r e unclassified, are d i s p r o p o r t i o n a t e l y less e d u c a t e d a n d m o r e elderly. nine o f the r e s p o n d e n t s aged a n d o v e r ( o r %) are a m o n g the unclassified. t w e n t y - n i n e o f the r e s p o n d e n t s with years o f e d u c a t i o n or less ( o r %) are a m o n g the unclassified. v. individual interpretations i n d i v i d u a l i n t e r p r e t a t i o n s o f a s h a r e d v i e w p o i n t c a n be clarified t h r o u g h unstruc- tured, f o l l o w - u p interviews with the best representatives. t h e best representatives are table sociodemographic description o f the respondents by cluster x x.i x. x. others totals age or less or more no report sex t l m ale female no report education (years) or less l or more i no report region east south i west [ totals t h o s e r e s p o n d e n t s w h o s e q - s o r t s h a v e t h e h i g h e s t c o r r e l a t i o n s w i t h t h e v i e w p o i n t p r o f i l e . i n t e r v i e w s w i t h f o u r o f t h e b e s t r e p r e s e n t a t i v e s o f t h e c o r e v i e w p o i n t a r e s u m m a r i z e d i n t.his s e c t i o n [ ]. a s s h o w n i n t a b l e , t h e i r q - s o r t s a r e a l s o p o s i t i v e l y c o r r e l a t e d w i t h t h e p e r i p h e r a l v i e w p o i n t p r o f i l e s . t h e i n t e r v i e w s w e r e u n s t r u c t u r e d in t h a t t h e r e p r e s e n t a t i v e s w e r e s i m p l y e n c o u r a g e d t o t a l k a b o u t t h e e n e r g y s i t u a t i o n w i t h a m i n i m u m o f s p e c i f i c a n d s u b s t a n t i v e c u e s f r o m t h e i n t e r v i e w e r . b e c a u s e t h e i n t e r v i e w s w e r e c o n d u c t e d a b o u t t w o m o n t h s a f t e r t h e q - s o r t s , t h e y p r o v i d e i n f o r m a t i o n a b o u t t h e d i r e c t i o n s o f e v o l u t i o n o f v i e w p o i n t s as w e l l a s p o t e n t i a l l y c o r r o b o r a t i n g i n f o r m a t i o n f r o m a n a l t e r n a t i v e o b s e r v a t i o n a l s t a n d p o i n t . m r s . a is a - y e a r - o l d , m i d d l e - c l a s s h o u s e w i f e , w h o h a s a h i g h s c h o o l e d u c a t i o n a n d l i v e s i n a s u b u r b o f a l a r g e m i d w e s t e r n c i t y . o f a l l t h e r e s p o n d e n t s , s h e is t h e b e s t r e p r e s e n t a t i v e o f t h e c o r e v i e w p o i n t . m r s . a a c k n o w l e d g e s t h a t a s a l a y m a n s h e is n o t k n o w l e d g e a b l e e n o u g h t o . k n o w h o w b a d t h e e n e r g y s i t u a t i o n is. b u t m r s . a a n d h e r family a n d friends have c o m e up with " c o n c e i v a b l e solutions" and she does not u n d e r s t a n d " w h y o u r representatives either c a n ' t or w o n ' t or d o n ' t see what we see as the little p e o p l e . " m o r e o v e r , those w h o publicly c o m m e n t on the issue have not d o n e m u c h themselves to i m p r o v e the situation. i t h i n k w e h a v e t h e a b i l i t y [ i n t h i s c o u n t r y ] , a n d t h a t w e h a v e t h e k n o w - b o w , a n d if t h e m o n e y h a s t o be g o t t e n , i ' m s u r e it c a n b e g o t t e n . h a v e t o . . . b e l i e v e it's a p o l i t i c a l t h i n g : t h a t t h e y won't d o a n y t h i n g a b o u t it. mrs. a believes t h a t s o m e politicians are honest a n d principled, a n d go to w a s h i n g t o n with g o o d intentions. b u t i t h i n k o n c e t h e y g e t t h e r e the} b e c o m e p a r t o f . . . t h e w a s h i n g t o n s c e n e , l t h i n k t h e y b e c o m e i n t i m i d a t e d , a n d t h e n b e c o m e i n t i m i d a t o r s . . . i t h i n k y o u e i t h e r j o i n t h e g r o u p , o r t h e y d o n ' t l et y o u p l a y in t h e g a m e . . . mrs. a w a n t s to believe t h e m , but feels t h a t realistically she c a n n o t . t h e y h a v e p r o m i s e d t o o m u c h a n d delivered t o o little, a n d h a v e " a n awful lot o f fence m e n d i n g '~ to do. " i t ' s not going to be easy f o r this c o u n t r y to totally believe in the men t h a t they put into office." a c c o r d i n g t o mrs. a, the oil c o m p a n i e s are t a k i n g a d v a n t a g e o f a n u n e x p e c t e d windfall a n d getting very rich. t h e y did not realize what was happening, but n o w " t h e y like w h a t ' s h a p p e n i n g and t h e y ' r e not g o i n g to do a n y t h i n g a b o u t it." t h e y are holding b a c k p r o d u c t i o n a n d creating s h o r t a g e s to drive the price up. (mrs. a sees s o m e parallels in increases in coffee a n d s u g a r prices a few years ago.) w h o stands to gain f r o m that? y o u a n d i - i k n o w w e w o n ' t . t h e o i l c o m p a n i e s w i l l g e t m u c h r i c h e r . t h e y a r e s u p p o s e d t o be r e i n v e s t i n g s o m u c h o f t h i s m o n e y i n t o c r e a t i n g n e w f o r m s o f e n e r g y . i a m s u r e w i t h a g o o d a c c o u n t a n t a n d a c o u p l e o f p r o b a b l y v e r y b r i g h t p e o p l e a r o u n d t h e y c a n m a k e it l o o k o n p a p e r t h a t t h e y ' r e d o i n g it. i t a b l e correlations b e t w e e n individual q - s o r t s and c o r e and peripheral v i e w p o i n t profiles v i e w p o i n t s m r s . a . . . . mr. b . . . . m r s . c . . . . mr. d . . . . r e s p o n d e n t s x x. x. x. [ don't really think they will [do it] . . . don't think they're really going to put that money back into production. the guy who works to keep his family together, put his kids through school he's the one who's going to suffer for it. the rich will only get richer and the poor will have medicaid and welfare . . . the guy who works for a living won't be able to afford it . . . m r s . a b e l i e v e s t h a t e n e r g y p r i c e s a r e n o t o n l y e x c e s s i v e , b u t " r i d i c u l o u s . " " b u t t h e y h a v e t h e p e o p l e b y t h e t h r o a t - w h a t a r e y o u g o i n g t o d o ? " m r s . a ' s s k e p t i c i s m c a r r i e s o v e r t o t h e n e w s m e d i a . i don't know how much of what the media tell us is the truth either. we're at the mercy of television and the newspapers and the radio, and you don't hear anything good anymore� you just hear a prophet of doom. and it's d e p r e s s i n g . . , l think we are given to read and to listen to ~hat they want us to hear and read. t h e r e s u l t o f t h i s is t h a t : people like us have become distrustful, have become fearful. they've scared us, they've frightened us into thinkingthat in another - years. god only kno~'s, we'll have no food, we'll have no energy. there won't be a n y t h i n g . . , l don't believe that it has to be that w a y . . . i don't know the answer, i just know that there's no confidence in the government, and i think, l really believe, that we've been lied to so many times that it is just like the little boy that cried "wolf'. a t a l a t e r p o i n t m r s . a p u t s t h e m a t t e r m o r e s u c c i n c t l y : � . . ignorance breeds fear. an,~ that's why people panic and get scared and don't think, and do things that they wouldn't do if they stopped and thought about it. it's because they just don't know what's really going on. m r s . a r e p o r t s t h a t s h e a n d h e r h u s b a n d h a v e c u t b a c k o n t h e i r c o n s u m p t i o n o f e n e r g y , a n d h a v e d e c i d e d t o s k i p t h e i r n o r m a l s u m m e r v a c a t i o n , a d r i v e o f s e v e r a l h u n d r e d m i l e s r o u n d t r i p . y e t s h e f e e l s l i k e s o m e t h i n g o f a s u c k e r , w i t h p e o p l e in w a s h i n g t o n , � . . having chauffeurs and flitting around the country� and then you figure, well why should [cut back]?� . . you get to the point when you really feel, what the beck. lt's going to happen anyway, i might as well enjoy myself before it does. and that's a sick attitude� i don't like t h a t . . . i don't like to have my children hear me talk like that. and it frightens me when i hear my kids talk like that . . . t h i s is a p r o f o u n d c o n f l i c t f o r m r s . a , r o o t e d in p a r t in h e r e x p e r i e n c e as a c h i l d g r o w i n g u p d u r i n g w o r l d w a r i i . n o b o d y c o m p l a i n e d a b o u t m a k i n g s a c r i f i c e s t h e n ; i n d e e d , p e o p l e t o o k p r i d e i n m a k i n g s a c r i f i c e s f o r t h e c o u n t r y . b u t " t h e p r i d e i n t h e c o u n t r y ' s n o t t h e r e t o d a y . , . y o u c a n ' t h a v e p r i d e i n s o m e t h i n g y o u d o n ' t t r u s t . " t h e i n f e r e n c e is i n e s c a p a b l e t h a t m r s . a f e e l s a d e e p b u t f r u s t r a t e d n e e d t o b e l i e v e in h e r c o u n t r y a n d i t s l e a d e r s , a n d t o " p u l l t o g e t h e r a n d t r y t o d o s o m e t h i n g " as s h e o n c e d i d . t h i s n e e d is r e f l e c t e d i n h e r p r i n c i p a l s u g g e s t i o n f o r d e a l i n g w i t h t h e e n e r g y s i t u a t i o n : � i f t h e s i t u a t i o n is as d e s p e r a t e a s t h e y l e a d us t o b e l i e v e , t h e o n l y w a y t h a t it's g o i n g t o g e t a n y b e t t e r , is t o g e t e v e r y b o d y t o w o r k t o d o it b e t t e r . a n d t h a t c a n o n l y c o m e f r o m t h e h i g h e r - u p s . s o m e t h i n g ' s g o t t o g i v e j u s t t o m a k e p e o p l e w a n t t o d o it. i d o n ' t k n o w h o w . t h e s e c o m m e n t s by mrs. a illuminate her i n t e r p r e t a t i o n o f a n u m b e r o f s t a t e m e n t s t h a t figure p r o m i n e n t l y in the core v i e w p o i n t profile. h e r c o m m e n t s b e a r i n g on several o t h e r s t a t e m e n t s , t h o u g h s u b s i d i a r y f r o m her viewpoint, are w o r t h reviewing briefly. mrs. a is upset by o u r c o n t i n u i n g d e p e n d e n c e o n foreign sources o f oil. as she puts it, " i hate to see foreign countries h a v e such a p o w e r o v e r us." she believes that we have the resources to increase p r o d u c t i o n a n d reduce this dependency, but lack the political will. e n h a n c e d p r o d u c t i o n o f coal a n d s o l a r energy, increased refinery c a p a c i t y , a n d energy-efficient designs in new buildings are a m o n g her " c o n c e i v a b l e solutions." while nuclear p o w e r might also r e d u c e o u r dependence, she is frightened by the health a n d safety implications. she did not give the m a t t e r m u c h t h o u g h t until the accident at t h r e e mile i s l a n d and s u b s e q u e n t disclosures o f accidents at o t h e r plants. " i d o n ' t think t h a t m o s t p e o p l e ' f u l l y u n d e r s t o o d w h a t nuclear p o w e r was a n d how powerful, h o w d a n g e r o u s , it c a n be." h o w e v e r , ~'i t h i n k if they [the authorities] have got their mind m a d e up to go the way o f nuclear power, t h e y ' r e going to d o it, and i d o n ' t think it m e a n s a hill o f beans what the p e o p l e think." mr. b is a - y e a r - o l d c l e r g y m a n w h o lives in a s o u t h a t l a n t i c state. h e is m o s t c o n c e r n e d a b o u t the s a f e t y o f his f a m i l y a n d w h e t h e r " o u r lives are g o i n g to be able to c o n t i n u e as they h a v e been - i f i c a n go w h e r e i w a n t to go a n d d o the things i w a n t to d o . " m o b i l i t y is a p a r t i c u l a r l y i m p o r t a n t m a t t e r o f life-style because mr. b's i m p e n d i n g m o v e to a n o t h e r p a r t o f the c o u n t r y is t h r e a t e n e d by the gas s h o r t a g e a n d the t r u c k e r s ' strike. w h a t is the source o f the p r o b l e m ? w e l l . . . d o n ' t k n o w . i t h i n k t h a t ' s t h e f r u s t ~ ' a t i n g p a r t o f it. i d o n ' t k n o w w h e t h e r it's g o v e r n m e n t o r w h e t h e r it's t h e o i l c o m p a n i e s , w h e t h e r it w a s j u s t p o o r p l a n n i n g f o r a l o n g t i m e . . . . i t h i n k t h e f r u s t r a t i n g t h i n g f o r m e is t h e f a c t t h a t i d o n ' t k n o w w h a t t o b e l i e v e , a n d i d o n ' t k n o w c a n r e a l l y t r u s t t h e m w h e n t h e y s a y s o m e t h i n g to m e a b o u t t h e e n e r g y s t u f f . . . i f i c o u l d see t h a t t h e y w e r e r e a l l y a d d r e s s i n g t h e p r o b l e m . . . i t ' s j u s t s o n e b u l o u s a n d s o u n c e r t a i n � c o u p l e d with this distrust a n d u n c e r t a i n t y is a sense o f political inefficacy: � . . i d o n ' t r e a l l y feel l i k e i h a v e a n y a r e n a t o d o a n y t h i n g a b o u t w h a t ' s g o i n g on. i t s e e m s t o m e t h a t t h o ~ e d e c i s i o n s a r e m a d e b y a few p e o p l e a n d i ' m n o t r e a l l y c o n v i n c e d t h a t t h e y a r e m a d e f o r t h e g o o d o f t h e p e o p l e . i t h i n k t h e y ' r e m a d e f o r t he g o o d o f t h e c o m p a n i e s , o f t h o s e p e o p l e w h o a r e g o i n g t o m a k e a l l k i n d s o f p r o f i t s o f f t h i s o i l stuff� mr. b has recently c o m e to believe in t h e l o n g - t e r m p o t e n t i a l o f solar energy, and s u p p o r t s c o n s e r v a t i o n as a m a t t e r o f p e r s o n a l a n d public action. but he describes nuclear safety a n d the d i s p o s a l o f r a d i o a c t i v e wastes as a m a i n concern, a n d his c o m m e n t s o n the accident at t h r e e mile i s l a n d stand out in t e r m s o f intensity. h e was " a n g r y " t h a t such plants had been built in p o p u l a t e d areas. and, � . . it seems like they had people in there who don't even know what they are doing. it also seems like the people who are supposedly able to regulate these things don't really have that much control over them, don't even have a whole lot of expertise in them. it's kind of shattering. m r s . c is a - y e a r - o l d h o u s e w i f e w h o d o e s v o l u n t e e r w o r k a n d l i v e s i n a n u p p e r - c l a s s n e i g h b o r h o o d o f a w e s t e r n c i t y . f o r h e r , " t h e m o s t i m p o r t a n t t h i n g is t h a t n e w s o u r c e s o f e n e r g y s h o u l d b e d e v e l o p e d a s r a p i d l y a s p o s s i b l e . " t h e s e i n c l u d e g a s o h o l , o i l s h a l e , s o l a r e n e r g y , a n d " a l l o f t h e n a t u r a l t h i n g s w e c a n u s e . " s h e is " v e r y m u c h o p p o s e d " t o n u c l e a r p o w e r : � . . we're gonna poison the world for our next generations to come because there's no place to put the waste. i just wish that the?,, would close down the ones that they started already and use all the money that they are funneling into that program [in] these other programs. i think we're playing with god when we mess around with that stuff. m r s . c b e l i e v e s t h a t e n e r g y p r i c e s a r e probably f a i r a n d . r e a s o n a b l e i f t h e y d o n o t c o n t i n u e t o g o u p , b u t i f p r o d u c t i o n is b e i n g w i t h h e l d t o r a i s e p r i c e s , " ' t h a t ' s w r o n g . " " i a m f o r t u n a t e t h a t w e c a n p a y f o r t h o s e t h i n g s w i t h o u r i n c o m e . i f e e l v e r y b a d f o r p e o p l e w i t h f i x e d i n c o m e s . " a l t h o u g h it is a p p a r e n t l y n o t n e c e s s a r y f o r f i n a n c i a l r e a s o n s , m r s . c h a s r e d u c e d t h e u s e o f h e r a u t o m o b i l e t o t h e p o i n t t h a t s h e p a y s n o m o r e f o r g a s o l i n e , i n s p i t e o f r e c e n t l a r g e i n c r e a s e s i n t h e p r i c e . m r s . c p r o f e s s e s s k e p t i c i s m , . . . about everything and everybody anymore. don't even like to hear news anymore, it's so d i s c o u r a g i n g . . . i don't have much faith in the president anymore or [in] the oil companies� m r s . c n o t e d a t a l a t e r p o i n t i n t h e i n t e r v i e w t h a t p e o p l e i n h e r a r e a p l a c e m o r e t r u s t i n l o c a l l e a d e r s . " t h e y f e e l t h e y h a v e a l i t t l e m o r e c o n t r o l o v e r t h e m . " m r . d is a - y e a r - o l d h e a v y c o n s t r u c t i o n w o r k e r w h o l i v e s n e a r a l a r g e m e t r o p o l i t a n a r e a i n a p l a i n s s t a t e . f r o m h i s v i e w p o i n t , � . . the most important thing is t h a t . . , changes need to be made to supply enough energy for the national growth. i think it's important to maintain the life-style of this country, which is probably one of the highest in the w o r l d . . . with technology, if there's an honest attempt made by all parties involved, we can start relying more heavily on our renewable energy sources and start conserving our fossil f u e l s . . . t h e s e n e e d s a r e r e l a t e d , i n m r . d ' s v i e w , t o l a r g e r p r o b l e m s o f s o c i a l a n d p o l i t i c a l s t a b i l i t y . h e b e l i e v e s t h a t p e o p l e " w i t h t h e b i g b u c k " h a v e t a k e n a d v a n t a g e o f t h e e n e r g y s i t u a t i o n a n d u n d e r m i n e d t h e l i f e - s t y l e s , t h e s t a n d a r d s o f l i v i n g , o f t h e l o w e r a n d m i d d l e c l a s s e s . t h i s p r o b l e m , � . . has to be worked out or you're going to run into real problems . . . you [will] get a massive discontent of the greater portions of this country, which are an educated people. i mean it's not a bunch of ignorant masses that are going to take somebody's word for something� they know better� i think that's the only threat to this country as far as revolution, and if they disturb enough people at the same time due to something like t h i s . . . mr. d r e t u r n e d to this t h e m e at t h e e n d o f the i n t e r v i e w w h e n a s k e d if he w o u l d like to m a k e a s u m m f f r y s t a t e m e n t . yes. think the country is going to have to do it peaceably. they're going to have to take the whole society into account and treat them like men, 'cause if you try and do something and put the whole burden on the shoulders of the guy that's hurting the worst anyway, you're going to run into trouble. mr. d. has little f a i t h in g o v e r n m e n t " r e d t a p e a n d b u r e a u c r a c y . " he also has little f a i t h t h a t t h e m a j o r oil c o m p a n i e s will a c c e p t r e a s o n a b l e profits a n d a v o i d t a k i n g " t o o big o f a bite at s o m e b o d y else's e x p e n s e w h e n it's j u s t t o t a l l y u n n e c e s s a r y . " he s u p p o r t s his c o n t e n t i o n t h a t e n e r g y price i n c r e a s e s a r e c o n t r i v e d by r e f e r r i n g to his o w n o b s e r v a t i o n s m a d e at j b s a r o u n d p o w e r p l a n t s a n d oil refineries: " . . . the r e a s o n s p u t o u t for the i n c r e a s e s in prices j u s t d o n ' t j i b e with w h a t i ' m s e e i n g every d a y . " t o m r . d, n u c l e a r p o w e r p l a n t s a r e " p o t e n t i a l l y h a r m f u l to p e o p l e " a n d t h e r e is n o need for t h e g o v e r n m e n t to r u s h t h e m o n line. they're going to have a bad accident and they're going to have everything out: "o. k., we're going to shut these down." so all of a sudden you've got all these things just sitting there, monuments to nothing. he e x p e c t e d s o m e t h i n g like t h e i n c i d e n t at t h r e e m i l e i s l a n d w o u l d h a p p e n , a n d he h a d h e a r d o f " a t least a h a l f a d o z e n o t h e r i n c i d e n t s t h a t n e v e r hit t h e news" f r o m f e l l o w c o n s t r u c t i o n w o r k e r s . m r . d believes t h a t a l a r g e n u m b e r o f s m a l l , d e c e n - t r a l i z e d g e n e r a t i n g s o u r c e s is a m u c h m o r e r e l i a b l e w a y to go, d e s p i t e r e s i s t a n c e by g o v e r n m e n t a n d i n d u s t r y . t h e l o c a l p o w e r c o m p a n y a p p a r e n t l y f r u s t r a t e d his a t t e m p t t o p u t u p a s m a l l w i n d g e n e r a t o r a n d tie it i n t o t h e l i n e b e t w e e n t h e m e t e r a n d t h e b r e a k e r b o x in his n e w h o m e . t h e s e i n t e r v i e w s a r e i n t e n d e d to clarify i n d i v i d u a l i n t e r p r e t a t i o n s o f the p r i n c i p a l s t a t e m e n t s in t h e c o r e v i e w p o i n t a n d to suggest s o m e of t h e o r i g i n s of these i n t e r p r e t a t i o n s . i t is b e y o n d t h e s c o p e o f this p a p e r to a t t e m p t a n e v a l u a t i o n o f the o p i n i o n s v o l u n t e e r e d in t e r m s o f t h e i r g r o u n d i n g in the facts o f t h e c u r r e n t c o n t e x t a n d t h e v a l u e s t h a t have b e e n a s s i m i l a t e d i n t o a m e r i c a n c u l t u r e t h r o u g h c e n t u r i e s of e x p e r i e n c e . t w o o b s e r v a t i o n s c a n be m a d e by w a y of c o n c l u s i o n , h o w e v e r . o n e is t h a t these o p i n i o n s c a n n o t be easily d i s m i s s e d as u n r e a l i s t i c o r u n w o r t h y i n p u t s to p o l i c y p l a n n i n g a n d e v a l u a t i o n [ ]. a n o t h e r is t h a t f o r p r o m o t i o n a l p u r p o s e s , t h e r e a l i s m a n d m o r a l w o r t h of these o p i n i o n s is a s e c o n d a r y c o n s i d e r a t i o n . t h e s e o p i n i o n s , to the e x t e n t they are shared, are i m p o r t a n t factors in shaping the success or failure o f any a t t e m p t to mobilize the public behind an energy plan or to elicit v o l u n t a r y compliance with energy policies already enacted. vi. t h e e v o l u t i o n o f v i e w p o i n t s in this section we consider the pattern of evolution of citizen viewpoints, b o t h past and prospective. short-term m o r e t h a n a year ago, a pilot study using a similar q -sam p l e in a m i d w e s t e r n city revealed three public viewpoints on energy policy. t h e y emphasized: ( l ) energy c o n s e r v a t i o n and e n v i r o n m e n t a l protect i o n , with little faith in either experts or the federal government. ( ) energy p r o d u c t i o n increases, m a i n t e n a n c e of living standards, and rejection of higher energy prices, with distrust of the federal g o v e r n m e n t and the energy industries. ( ) rejection of g o v e r n m e n t intervention, faith in the market, an d the need for higher energy prices, coupled with distrust of the public. according to an independent estimate, the second viewpoint comprised a b o u t two-thirds to t h r e e - q u a r t e r s of the national p o p u l a t i o n , while the first and third viewpoints included a b o u t one-eighth and one-tenth, respectively [ ]. a l t h o u g h the pilot study is far f r o m conclusive, it does provide a suggestive benchmark. based on similarities with the current results, the second viewpoint in the pilot study appears to be the c o m m o n a n t e c e d e n t of b o t h the core viewpoint x and the peripheral viewpoints x. and x. ; the first viewpoint appears to be the direct an t eced en t o f the x. viewpoint; and the third (or m a r k e t - o r i e n t e d ) viewpoint appears to have d i s a p p e a r e d as a distinctive, shared viewpoint. t o be sure, a n u m b e r o f the r e s p o n d e n t s in the c u r r e n t study sorted certain statements (app. , , , , ) in ways that can be interpreted as market-oriented, an d six respondents p r o v i d e d a relatively consistent pattern in this direction. but the m ark et -o ri en t ed perspectives of these six are s u b o r d i n a t e to other perspectives, and the distances a m o n g their q-sorts are relatively large. one is classified as a m e m b e r of x, a n o t h e r as a m e m b e r o f x. , and the remaining f o u r are scattered a m o n g the unclassified peripheral respondents. based on differences between the earlier results and the current results, it appears that health, safety, and e n v i r o n m e n t a l concerns have intensified relative to others over time; and that opinions on nuclear power have intensified and shifted in the direction o f o p p o s i t i o n , p a r t i c u l a r l y o p p o s i t i o n to the siting o f new nuclear plants in n e a r b y areas. t h e most plausible i n t e r p r e t a t i o n is that these changes represent the impact of the incident at t h r e e mile island, which focused and sustained a t t e n t i o n in the news f o r several weeks. (quite unintentionally, the q-sorts were o b t a i n e d in the five-week period immediately following the incident.) r e p r e s e n t a t i v e s o f the core v i e w p o i n t are now s t r o n g l y o p p o s e d to new nuclear p o w e r plants in the areas where they live, h a v i n g been impressed, p r e s u m a b l y , by the i m p a c t o f the incident on people like themselves in the h a r r i s b u r g area. (see the c o m m e n t s on the incident in the interview s u m m a r i e s above.) a p p a r e n t l y , nuclear p o w e r is n o w perceived less as a source o f energy t h a t c o n t r i b u t e s to d o m e s t i c energy p r o d u c t i o n a n d living s t a n d a r d s t h a n as a t h r e a t to public health, safety, a n d the e n v i r o n m e n t . t h o u g h r e p r e s e n t a t i v e s o f the x. v i e w p o i n t are less o p p o s e d to new nuclear p o w e r plants in their areas t h a n are the representatives o f the core viewpoint, they are now noticeably m o r e concerned a b o u t public health a n d safety. t h e representatives o f the x. v i e w p o i n t a p p e a r to be unaffected. t h e i r s h a r e d viewpoint remains a r o u g h a p p r o x i m a t i o n to the second viewpoint in the pilot study. i n short, the incident at t h r e e mile i s l a n d a p p e a r s to have precipitated m o v e m e n t o f the second p i l o t - s t u d y v i e w p o i n t in the direction o f the first, a n d mitigated the differences b e t w e e n tlae two. at the s a m e time, the issue o f n u c l e a r siting raised by the incident a p p e a r s to have split the second v i e w p o i n t into two peripheral variations. i n a r o u g h a n d a p p r o x i m a t e way, this p a t t e r n o f e v o l u t i o n a p p e a r s to a c c o u n t f o r the principal differences between the results o f the two studies. t h e i m p a c t o f the incident at t h r e e mile island as r e c o n s t r u c t e d here m a y dissipate in relative intensity as t h r e e mile i s l a n d recedes f u r t h e r into the past a n d o t h e r events d o m i n a t e public attention. t h e u n s t r u c t u r e d interviews s u m m a r i z e d a b o v e p r o v i d e s o m e p r e l i m i n a r y indications. a l t h o u g h s t r o n g o p i n i o n s were still expressed in o p p o s i t i o n to nuclear p o w e r in j u n e , o t h e r issues were d e e m e d m o r e i m p o r t a n t . longer-term o t h e r t h e m e s in the core a n d p e r i p h e r a l viewpoints - e c o n o m i c insecurities (if not hardships), distrust, disbelief, disaffection, a n d u n d e r t o n e s o f m o r a l o u t r a g e - have t e n d e d to persist o v e r several years. t h i s persistence is r o o t e d in r e c u r r i n g events, p a r t i c u l a r l y sustained energy price increases a n d i n t e r m i t t e n t shortages, and state- m e n t s a b o u t t h e m circulated t h r o u g h the n a t i o n a l news media. t h e s e are the principal ways in which the energy s i t u a t i o n enters into the experience o f individual citizens a n d to s o m e extent c o o r d i n a t e s their viewpoints [ ]. a struggle o v e r n a t i o n a l energy policy is c o n d u c t e d t h r o u g h the news m e d i a because the p r i n c i p a l factions o f the p o l i c y - m a k i n g elite have been u n a b l e to agree a m o n g themselves on a n u m b e r o f key issues, despite their access to expert o p i n i o n and analyses [ ]. u n d e r these circumstances, each faction perceives a n o p p o r t u n i t y to a d v a n c e its policy p o s i t i o n s a n d interests by a p p e a l s to a larger audience. d i a g n o s e s a n d p r e s c r i p t i o n s circulated to the p u b l i c t h r o u g h the news m e d i a by one f a c t i o n tend to be c o n t r a d i c t e d by one or m o r e o f the others, who s o m e t i m e s also a t t e m p t to discredit the o p p o s i t i o n directly. m o r e o v e r , s o m e s t a t e m e n t s circulated f o r public c o n s u m p t i o n are perceived to be c o n t r a d i c t e d by o b s e r v a t i o n s a n d i n t e r p r e t a t i o n s t h a t citizens can m a k e on their own. f o r e x a m p l e , the a s s e r t i o n t h a t we are faced with a p r o f o u n d crisis tends to be u n d e r m i n e d w h e n projected s h o r t a g e s d o not materialize; a n d the localized a n d t r a n s i t o r y s h o r t a g e s t h a t have o c c u r r e d t e n d to be i n t e r p r e t e d in p a r t as d e l i b e r a t e a t t e m p t s to force price increases [ ]. m e a n w h i l e , e v e r y o n e has experienced increases in gasoline a n d utility bills, but few perceive significant progress t o w a r d such widely a c c l a i m e d goals as r e d u c i n g o u r d e p e n d e n c e o n foreign sources o f oil. t h e s h o r t - t e r m i m p a c t s on the public are not exclusively or even p r i m a r i l y e c o n o m i c . t o be sure, p o o r a n d f i x e d - i n c o m e h o u s e h o l d s h a v e suffered e c o n o m i c hardships. but middle- and u p p e r - i n c o m e h o u s e h o l d s so far have been able to a c c o m m o d a t e increased energy costs with relatively m i n i m a l strain on h o u s e h o l d budgets, a n d energy shortages so far have been localized a n d t e m p o r a r y for all i n c o m e classes. o n e i m p o r t a n t i m p a c t is the calling into question of p r i o r beliefs. f o r example: - s o m e o n e m u s t u n d e r s t a n d the situation. but why do the experts disagree? w e h a v e a lot o f k n o w - h o w in this c o u n t r y . but why c a n ' t we soh, e the p r o b l e m ? - w e ' v e m a n a g e d so far. but what's going to h a p p e n in the future? - i p a y m o r e for energy now. but why d o e s n ' t this increase energy supplies? - a m e r i c a n s pull t o g e t h e r in a crisis. but is there really a crisis? - i ' m r e a d y to do m y part. but a m i being t a k e n for a sucker if i do? - o t h e r s h a v e been affected the s a m e w a y i have been. but why d o n ' t they listen to us? t h i s is a g o v e r n m e n t o f the people. but does it p r o t e c t the interests o f people like me? a n o t h e r i m p a c t is to question the preferences built into individual life-styles: - w h a t will i have to give up? still a n o t h e r is to question previous loyalties: - w h o m can i trust? w h e r e such questions are difficult to resolve at the p e r s o n a l level, anxieties a n d insecurities c u m u l a t e a n d w e a k e n the c o n s t r a i n t s o f r e a s o n a n d conscience. t h i s increases the d e m a n d for e m o t i o n a l l y satisfying r a t h e r t h a n realistic or just solutions, o n e such e m o t i o n a l l y satisfying " s o l u t i o n " is s c a p e g o a t i n g , which provides t e m p o r a r y relief o f the s y m p t o m s (catharsis) [ ]. it is no accident t h a t p e r s o n a l insecurities arising f r o m the energy situation ( a n d o t h e r sources as well) are displaced o n the president, the g o v e r n m e n t generally, the oil a n d gas industry, o t h e r energy industries, a n d the like. f o r one thing, they figure m o s t p r o m i n e n t l y in the energy d e b a t e in w a s h i n g t o n , as c o v e r e d in the news o v e r the last several years. f o r a n o t h e r , they have consistently f o c u s e d a n d refocused the d e b a t e on energy price increases. t h a t e n e r g y prices s h o u l d increase is largely a m a t t e r o f consensus in w a s h i n g t o n . w h a t has been at issue is: w h o should a d m i n i s t e r the price increases, at w h a t rate, and w h o should dispose o f the proceeds? t h e principal o p t i o n s are g o v e r n m e n t and business ( t h r o u g h reliance o n " m a r k e t " processes). t h e energy price d e b a t e e n c o u r - ages the a s s u m p t i o n t h a t g o v e r n m e n t a n d business are to blame: citizens tend to view energy price increases as the p r o b l e m , not the solution [ ]. g o v e r n m e n t and business, in short, are b o t h highly visible and plausible targets. t h e effects are multiple a n d reinforcing. responsibility and b l a m e are focused on g o v e r n m e n t a n d business. this f u r t h e r undermines trust in g o v e r n m e n t a n d business, a l r e a d y in d o u b t before the - oil e m b a r g o . distrust further reinforces the t e n d e n c y to discount s t a t e m e n t s a b o u t the n a t i o n ' s energy situation f r o m these sources, s o m e t i m e s w i t h o u t e x a m i n i n g t h e m carefully. p e o p l e fall b a c k on their own o b s e r v a t i o n s a n d i n t e r p r e t a t i o n s in a n a t t e m p t to m a k e sense o f the situation. but this selective focus leaves m a n y key questions unresolved, a n d insecurities are f u r t h e r e x a c e r b a t e d . f o r the r e s p o n d e n t s included in this study, w h a t e v e r hopes r e m a i n for a better f u t u r e a p p e a r to be displaced o n s o l a r e n e r g y a n d to a lesser degree c o n s u m e r o r g a n i z a t i o n s . b o t h s o l a r energy a n d c o n s u m e r o r g a n i z a t i o n s so far have a s s u m e d a relatively peripheral role in the n a t i o n a l energy debate. t h e s y m p t o m s o f such a d j u s t m e n t s a p p e a r to be manifest in the viewpoints e x p l o r e d in this s t u d y a n d in p r e v i o u s studies. t h e energy s i t u a t i o n viewed f r o m the grass r o o t s is indeed different f r o m the energy s i t u a t i o n as seen f r o m w a s h i n g t o n . t h e political p r o b l e m so f a r is less the existence o f these differences a n d the c u m u l a t i o n o f insecurities t h a n o u r inability to deal with t h e m constructively. at s o m e level, however, the c u m u l a t i o n o f insecurities interferes with c o n s t r u c t i v e p r o b l e m solving. a l o o k a h e a d w h a t c h a n g e s in v i e w p o i n t s m i g h t o c c u r o v e r the r e m a i n d e r of t h e m o s t p r o b a b l e p r o j e c t i o n is f u r t h e r intensification o f insecurities. reassurances, pessimistic forecasts, a n d a d d i t i o n a l plans a n d e x h o r t a t i o n s f r o m w a s h i n g t o n or f r o m c o r p o r a t e h e a d q u a r t e r s will p r o b a b l y have little effect on the e v o l u t i o n o f public viewpoints, unless they d e p a r t substantially f r o m previous a n n o u n c e m e n t s a n d m a k e sense in t e r m s o f the direct e x p e r i e n c e o f individual citizens. b o t h practice a n d s y s t e m a t i c inquiry indicate t h a t p r o p a g a n d a a n d o t h e r r e p r e s e n t a t i o n s t h a t are inconsistent with p r e d i s p o s i t i o n s t e n d to have little effect, unless s u p p o r t e d by s o m e t h i n g m o r e t h a n words. a m o n g the key p r e d i s p o s i t i o n s in this instance are distrust a n d disbelief. w h a t e v e r is said a n d d o n e in w a s h i n g t o n or c o r p o r a t e h e a d q u a r t e r s , the price increases n o w o r i g i n a t i n g in p a r t in the middle e a s t will generate a d d i t i o n a l tension, a n d this will be e x a c e r b a t e d by the i m p e n d i n g recession. s o m e c h a n g e s are possible, however. u n a n t i c i p a t e d events like the incident at t h r e e mile i s l a n d c a n n o t be ruled out in nuclear policy o r in energy policy generally. a n o t h e r possibility is t h a t the early stages o f the p r e s i d e n t i a l election c a m p a i g n will surface a p e r s o n w h o can t a p the existing tension a n d insecurities, satisfy the needs for credibility a n d reassurance, a n d m o b i l i z e the public behind new energy policies that could be c o n s t r u c t i v e o r destructive. i f one " s o l u t i o n " to the e m o t i o n a l d e m a n d s o f the s i t u a t i o n is scapegoating, a n o t h e r m a y be blind sub- servience to a leader w h o a p p e a r s to satisfy those demands. still a n o t h e r possibility is t h a t p e r s o n a l insecurities, social tension, a n d a general sense of crisis m a y be deliberately e x a c e r b a t e d by w o r d or deed, o n the e x p e c t a t i o n t h a t citizens a n d o r g a n i z e d g r o u p s w o u l d t h e r e f o r e s u b o r d i n a t e their perceived self- interests a n d pull t o g e t h e r in c o n c e r t e d ( a n d p e r h a p s desperate) action. w h e t h e r s o m e t h i n g like this has a l r e a d y o c c u r r e d in e n e r g y policy is difficult to d e t e r m i n e on the evidence available. i n a n y case, a g r e e m e n t on m a j o r energy issues has been realized d u r i n g s h o r t - t e r m emergencies such as the - oil e m b a r g o ; a n d recent gasoline s h o r t a g e s o n the west a n d east c o a s t s have been viewed as a m a j o r p r o m o t i o n a l o p p o r t u n i t y . finally, there is a possibility o f a concerted a t t e m p t to deflect responsibility a n d b l a m e for the energy situation a w a y f r o m the principals in the d o m e s t i c policy d e b a t e a n d t o w a r d a l t e r n a t i v e targets overseas, p a r t i c u l a r l y the o i l - e x p o r t i n g countries. w h a t e v e r the consequences for d o m e s t i c politics, this tactic entails a n increased risk o f c u r t a i l m e n t s in the g l o b a l s u p p l y o f oil a n d a n increased risk o f a r m e d conflict. a d v o c a t e s o f n o n v i o l e n t a c t i o n m a y be partially reassured t h a t the public for the t i m e being is p r e d i s p o s e d against the t h r e a t or use o f military force (see app. ). t h e p r o b l e m of p r o j e c t i n g s h o r t - t e r m m o v e m e n t s in citizen viewpoints is particu- larly difficult in the current situation. o n the one hand, heightened p e r s o n a l insecurities, social tension, a n d distrust are destabilizing. t h e inner c o n s t r a i n t s o f conscience a n d r e a s o n have been weakened, a n d there exists a n e n o r m o u s a m o u n t of e m o t i o n a l energy t h a t can be t a p p e d a n d c h a n n e l e d in m a n y directions. o n the o t h e r h a n d , the political s t a l e m a t e in w a s h i n g t o n , which a c c o u n t s in p a r t for the e m o t i o n a l climate, is r o o t e d in p e r c e p t u a l a n d political rigidities t h a t have persisted a n d intensified o v e r several years. w h e t h e r the s t a l e m a t e will be b r o k e n or circumvented, and if so how, are the key uncertainties. vii. c o n c l u s i o n o u r energy p r o b l e m s are at least as m u c h perceptual, political, a n d m o r a l as they are e c o n o m i c a n d technical. t h e cost o f o u r present inability to solve these p r o b l e m s c a n n o t be m e a s u r e d in dollars or b t u ' s alone. t h e cost includes not only distrust a n d disbelief, which c o m p l i c a t e the a d o p t i o n of policies t h a t might otherwise be acceptable; it also includes declining confidence in o u r institutions of g o v e r n m e n t , law, a n d politics. f o u n d e d on m o r a l consensus, these institutions are prerequisites f o r the o r d e r l y c o n d u c t o f the m y r i a d t r a n s a c t i o n s t h a t t a k e place in a m o d e r n society. t h e s e t r a n s a c t i o n s include, o f course, the p r o d u c t i o n a n d e x c h a n g e o f g o o d s a n d services, a n d the d e v e l o p m e n t a n d d i s s e m i n a t i o n o f technical innovations. declining confidence in public institutions is m u c h m o r e t h a n a m i n o r externality: it could t u r n out to be the m a j o r cost o f the energy crisis. t o m i n i m i z e the cost o f the t r a n s i t i o n to a s u s t a i n a b l e energy future, the i m m e d i a t e t a s k is to reduce the rising levels o f social tension a n d p e r s o n a l insecurities. t h e s e increase the risks o f e m o t i o n a l l y satisfying but destructive " s o l u t i o n s . " t h e t a s k is complicated by widespread public o p p o s i t i o n to the m a j o r energy policy alternatives a d v a n c e d so far. it is f u r t h e r c o m p l i c a t e d by distrust o f leaders identified with those alternatives, distrust sufficiently pervasive to render ineffective their future p r o m o - tional efforts [ ]. a l t h o u g h payoffs that are tangible and visible to the public might eventually dissipate these barriers, the major policies n o w in place o r p ro p o sed are not e x p e c t e d to realize such payoffs in the short run. r e s t o r a t i o n of trust and confidence is a long-run proposition. we need to rethink energy policies in both the public and private sectors, taking into a c c o u n t the viewpoints that exist at the grass roots. on e possibility fo r ci rcu m v en t i n g the existing perceptual and political barriers and p ro v i d i n g tangible and visible payoffs in the short run is a decentralized strategy [ ]. t h e federal g o v e r n m e n t might encourage local communities to deal with certain aspects o f the energy situation, particularly energy c o n s e r v a t i o n and the i m p l e m e n t a t i o n o f small-scale technologies to utilize renewable resources like solar energy [ ]. o u r results show a significant degree of public consensus on the need to develop renewable resources like solar energy ( _ ), and to p r o v i d e " b e t t e r i n f o r m a t i o n a b o u t how the energy crisis affects me and my c o m m u n i t y , and what we can do a b o u t it" ( ) (see tab l e ). in any case, those who are influential in energy policy, and who would therefore be the prime targets in an eruption o f moral outrage, have the largest stake in the cultivation of alternative strategies. n o t e s o n q - t e c h n i q u e s , see w. s t e p h e n s o n . the study o[ behavior: q-technique and lts methodology (chicago: u n i v e r s i t y of c h i c a g o press, ); s. r. brown, " i n t e n s i v e analysis in political research," political methodology, i ( w i n t e r , ), pp. - : a n d a text by s. r. b r o w n f o r t h c o m i n g f r o m the yale university press. r e c e n t d e v e l o p m e n t s are reviewed in operant subjectivity, edited by s. r. b r o w n at k e n t s t a t e university, kent, o h i o . a t h e o r e t i c a l f r a m e w o r k is u s e d to s a m p l e the universe o f relevant s t a t e m e n t s , a n d not to i m p o s e one set o f m e a n i n g s (the investigators') on the s t a t e m e n t s to t h e e x c l u s i o n of others. t he f r a m e w o r k u s e d to develop this q - s a m p l e is based on eight value categories (power, respect, rectitude, affection, wealth, well-being, skill, e n l i g h t e n m e n t ) a n d five categories o f the p r o b l e m - o r i e n t a t i o n (goals, trends, c o n d i t i o n s , projections, policy alternatives). t h e last category, policy alternatives, was used twice. e a c h o f t h e x = c o n c e p t u a l possibilities is r e p r e s e n t e d by one s t a t e m e n t in the q - s a m p l e . as r e p r o d u c e d in t h e a p p e n d i x , t h e c o l u m n s f r o m left to right r e p r e s e n t t h e v a l u e categories in t h e o r d e r listed above; t h e rows f r o m t o p to b o t t o m r e p r e s e n t the categories o f t h e p r o b l e m - o r i e n t a t i o n in the order listed above. f o r e x a m p l e , s t a t e m e n t _.(we s h o u l d do w h a t e v e r we c a n to m a k e o u r j o b s a n d i n c o m e s less d e p e n d e n t on f o r e i g n oil) c a n ~be f o u n d in the first row a n d c o l u m n . it f o r m u l a t e s a power goal, reduced d e p e n d e n c e . f o r a n e x p l i c a t i o n o f these categories, see h. d. lasswell, . pre- view o f policy sciences (new york: elsevier, [ ), chs. a n d . t h e s t a n d a r d text is p. h. a. s h e a t h a n d r. r. sokal, numerical taxonomy: the principles and practice o f numerical classification ( s a n francisco: w. h. f r e e m a n . [ ). see also k. d. bailey, "'cluster a n a l y s i s , " in sociological methodology ( s a n francisco: j o s s e y - b a s s , ), c h a p t e r , edited by d. r. heise; a n d r. k. blashfield a n d m. s. aldenderfer. "whe literature on cluster analysis," muhivariate behavioral research, ( j u l y ), pp. - . s n e a t h a n d sokal, op. cit., p. . a n a n a l o g y illustrates t h e point. t o d i s t i n g u i s h apples, o r a n g e s , a n d o t h e r kinds o f fruit, it is sufficient to d r a w a small, diverse s a m p l e t h a t includes at least a few s p e c i m e n s o f each. a large, r a n d o m s a m p l e is s u p e r f l u o u s for this p u r p o s e , a l t h o u g h essential for e s t i m a t i n g t h e p r o p o r t i o n s o f pre-specified types in t h e p o p u l a t i o n f r o m s a m p l e data. t h e r e are no s a m p l i n g d i s t r i b u t i o n s to assist the i n t e r p r e t a t i o n of cluster results, even if r a n d o m s a m p l i n g p r o c e d u r e s are used in d a t a collection. o n this point see t h e interview s u m m a r i e s in the n e x t section a n d bee angell a n d associates, inc.. " a q u a l i t a t i v e s t u d y o f c o n s u m e r a t t i t u d e s t o w a r d e n e r g y c o n s e r v a t i o n " [ n o v e m b e r , ), prepared for t h e office o f e n e r g y c o n s e r v a t i o n a n d e n v i r o n m e n t , federal e n e r g y a d m i n i s t r a t i o n . in verbaxim c o m m e n t s m a d e in u n s t r u c t u r e d g r o u p d i s c u s s i o n s , people t e n d to s u p p o r t their o p i n i o n s o n energy issues with f i r s t - h a n d o b s e r v a t i o n s or with s e c o n d - h a n d o b s e r v a t i o n s f r o m relatives a n d a c q u a i n t - ances. s t a t e m e n t s a n d a c t i o n s by t h e p r e s i d e n t a n d b u s i n e s s leaders are n o t c o n s i s t e n t l y used for the s a m e purpose. o n the c o n t r a r y , t h e y tend to be rejected explicitly. all interviews were c o n d u c t e d by one o f t h e two a u t h o r s or both. t h e interview with mrs. a t o o k place in h e r h o m e o n j u n e . t h e interviews w i t h mr. b, mrs. c, a n d mr. d were d o n e by l o n g - d i s t a n c e t e l e p h o n e on j u n e . d u r i n g t h e s a m e period we interviewed f o u r o t h e r r e s p o n d e n t s w h o were a m o n g the best r e p r e s e n t a t i v e s o f the p e r i p h e r a l v i e w p o i n t s . t h e s e interviews are not s u m m a r i z e d here because o f space limitations. f o r e x a m p l e , b o t h public o p i n i o n s a n d e x p e r t o p i n i o n s are selective, b u t in different ways. t h e t e n d e n c y o f t h e f o r m e r to rely o n f i r s t - h a n d o b s e r v a t i o n s in t h e i m m e d i a t e s u r r o u n d i n g s is not necessarily less reliable ( a c c o r d i n g to c o n v e n t i o n s o f evidence) t h a n the t e n d e n c y o f t h e latter to rely on o b s e r v a t i o n s f r o m a r o u n d t h e c o u n t r y or the globe t h a t are m a n y times r e m o v e d f r o m direct e x p e r i e n c e , a g g r e g a t e d , a n d filtered t h r o u g h a n u m b e r o f interested parties. t h e c o n g r e s s has persistently q u e s t i o n e d t h e d e p e n d a b i l i t y a n d the credibility o f t h e i n f o r m a t i o n u s e d in n a t i o n a l energy policy p l a n n i n g a n d e v a l u a t i o n . see, for e x a m p l e , the c o n g r e s s i o n a l l y m a n d a t e d r e p o r t o f the p r o f e s s i o n a l a u d i t a n d review t e a m , activities o f the qffice o f energy in/ormation and analysis. federal energy administration ( d e c e m b e r , ). m o r e o v e r , the principle o f g o v e r n m e n t of, by, a n d for t h e people is at least as s t r o n g in o u r c u l t u r a l heritage as the principle t h a t s y s t e m a t i c inquiry s h o u l d e n l i g h t e n public policy. (notes c o n t i n u e d on page ) . w e sh o u ld d o w h at ev er w e ca n to m ak e o u r jo b s an d in co m es le ss d ep en d en t o n f o re ig n o il . (+ . , , + . , + , ) . e n vi ro n m e m a l ac ti v is ts h av e cr ip p le d t h e g ro w th o f th e n u cl ea r p o w er m d n sl ry in l h is c o u n tr y . ( . , + . , . , + . ) _. = o il a n d n at u ra l g as h av e b ee n w it h h el d fr o m t h e m ar k et to f o rc e co n su m er p ri ce i n cr ea se s. (+ . , + . , + . , + , ) ,_. .~ r en ew ab le e n er g y s o u rc es li k e so la r p o w er a n d s m al l ri v er d am s co u ld b e co n tr o ll ed by p eo p le i n th is c o m m u n it y . (+ . , + i, , + . , . ) . l su p p o rt l aw s to p re ve nt th e m a jo r o il co m pa ni es fr o m c o n - tr o lli n g o th e r en er gy s ou rc es l ik e c o a l u ra n iu m , a n d s o la r co lle c- to rs . (+ . , + . , + . , + . ) .. .~ if a n e n er g y c ri si s is i n tp o se d o n us , [ w o u ld su pp m -i l h e ih re al o r us e o f m il il ar y f o rc e to d ea l w it h i t. . , . , . , . ) a pp en di x: th e q -s a m p le o f s ta le m e n ls . e n er g y s el f- re li an ce i n ea ch lo ca l c, ,m m tu n it y sh o u ld b e a b as ic p ri n ci p le o f n at io n al en er g y p o li cy . , w e sh o u ld n u rt u re a r es o u rc e- co n se rv in g e th ic , in w h ic h h u m an sa ti sf ac ti o n d ~ p en d s m u ch le ss o n m at er ia l co n su m p ti o n . (+ i. i, + ,+ . , ) (+ , ,+ . ,+ , , + ) _ ,;. p eo p le l ik e m e ar e ig n o re d w h en b ig g o v er n n te n t an d b ig b u si n es s m ak e en er g y p o li cy i n w a sh in g to n (+ . , + . l, + (i . , + . ) . it 's t h e re sp o n si b il it y ol t h e g as a n d e le ct ri c c o m p a n y to m ak e su re w e h av e p le n ty o f en er g y ( . , . , . , , ) . a d v er ti se m en ts an d sp ee ch es te ll in g p eo p le w h at t o t h in k a n d d o a b o u t en er g y a re o ft en in su lt in g . . im p ro v em en ts in t h e a m er ic an sl an d ar d o f li v in g d ep en d o n th e p ro d u ct io n an d u se o f m o re ,e n er g y . ( . , + . , + . , , ) (+ . . . , . , + . ) : e v en tu al ly w e sh al l le ar n o re sp ec t th e n at u ra l en v ir o n - m en t ra th er fl la n o v er w h eh n it , (+ . , t .q , + . , + . ) i . i w is h t h e g o v e, rn m en t w o u ld as k m e w h at i th in k a b o u t th e en er g y s it u at io n . (+ i. , + . , . i , + ) , ) , i w an t m y r ep re se n ta ti v es in w as h in g to n to m ak e w h at ev er d ea ls a re n ec es sa ry to g et s o m e ac ti o n o n e n er g y p o li cy . (- i. . + . , . ,+ , ) ~ t h e m ar k et w il l al lo ca te e n er g y su p p li es e ff ic ie n tl y a n d fa ir ly w h en p ri ce s ar e n u l o n g er c o n - tr o ll ed b y th e g o v er n m en t. ( . , . , - i.i , ) . ] th in k i t's w ro n g t o p ro m o te in cr ea se d e n e rg y co n su m p ti o n th ro u g h a d ve rt is in g c am pa ig ns . (+ . . + . , + . , + . ) . i w o n' l cu t b ac k c, u m y e n er # y us e u n li ] o th er s m ak e th e sa m e sa cr il ic e. ( , .i , . , . ) . p eo p le l ik e m e sh o u ld tr u st t h e p re si d en t to l in d a s o lu ti o n to t h e en er g y c ri si s. ( . , . , . ,- . ) ~ t h e o il a n d g as c o m p an ie s d es er v e th e tr u st o f p eo p le li k e m e. ( . , . ~ . . . ) t ho ,~ e p eu p le w h o d ir ec t lh ei r h o st il it y t o w ar d b u si n es s o r g o v er n - m en t w h en e n er g y p ro b le m s ar is e ar e .j us t lo o k in g f o r sc ap eg o at s. ( , . . , . , + . ) . ..a p eo p le i n th is c o m m u n it y w il l tr u st th e lo ca l g as a n d e le ct ri c co m - p an ie s to d 'j w h at 's b es t io r al l o f us , ( . , . , . , . ) . i t h in k w e sh o u ld g et t o g et h er in th is c o m m u n it y to w o rk o n o u r o w n l o ca l en er g y p ro b le m s. (+ i , . + . , + . , + . ) , i su p p o rt o rg a n iz a ti o n s th a l w o rk f o r co n su m er in te re st s o n en er g y i ss u es . (+ , + . , ~ . , + ~ .% l', ,a i( . w e sh o u ld in cr ea se th e p ro - d u c ti o n c, f {i ll a n d g as i n th e u .s . as r ap id ]) ' as p o sb ib le . { + . .+ . , . , + i. ) ; c o n su m e r pr ic e~ , o f g a so b n e , n a u ra l g as . fu el o a n d el ec tr ic ip v ar e to o l ow '. ( . , . , , , . ) __ : t il e a m c ri c a n p eo p le c an h a, ,c m o re e n er g y o n ly i f th ey a r~ " w il li n g t o p ay h ig h er p ri ce s io r it . ( i, i, . , i. i, . ) . i h e w u rl d is h ea d ed to w ar d sk v rn c k e ti n g o il p ri ce s an d w id e- sp re ad cn e[ g y s h n rl ag e: -, i n tl' ,t" m id - 's . (+ , , + . , + . . + . ) g . [ su p p o rt [e li i v al o fg o ', e rn il le n l re g u ]a ll o n s al ld e rm t ro b , o il o il a n d n a u lr a l g as p ri ce s. ( . , , i.( ), . ) ..: l ~ ,u p p o rl t ax es o n t h e w in d - fa ll p r, .d it ', o f ah e o il a n d gi n, in d u st ry . ( . , f . . + , . ( }. w e sh o u ld a cc ep t a d d it io n a l ri sk s to p u b li c h e a lt h a n d ~, a[ et y in o rd e r to d e a l w it h th e cn ~ '[g y cr is is . ( . , . . . . . ) __ : p eo p le li k e tn r ar c t ir ed o f se ei n g " th e en er g y cr is is " in t h e h ea d li n es al te r al l th c. se , ,r ea rs . ( . ,- i- . . i. i, . } ~ . a n in cr ea se in g a~ a n d el ec tr ic b il ls m ea n. ', m o re h a rd sh ip ju t il le p o o r a n d th o se o n l ix cd in co m es . (+ . , . , . , + ) . r c a li sl ic a lb , ti lt : n at io n h as no a lt er n at iv e b il l to i n cr ea se ils d e p e n d e n c e o n n il e[ ca r p o w er . ( , . + . , . , + . ) . i h a~ c n o o b ic cl io n to i ]t c lo ca ti o n ol a n ew n u cl ea r p o w er p la n l in t h e ar ea w , h er e i li v e. ( . , . . . ,+ . ) . [ su p p o rl ~ ig o ro tl s en fo rc e m en t o l ex is ti n g r p ro te ct io n i/ iw s a n d re g u la ti o n s. (+ . . + . . . , l. l) __ ~ o n ly t h e ex p er t. ', ~ ,h ou ld b e co n si d er ed c o m p e te n t to s a+ ,, w h at ca n b e d o n e a b o u t th e en er g y si tu at io n . ( . . . ~ , . , . ) . n o t ev en ih e ex p er ts k n o w h o w t o s af cl y d is p o se o ra d io - ac ti v e w as tc s [l o m n u cl ea r p o w r p la n ts . (+ . , + . , . , + . ) m . n ew e n er g y ic ch n o lo g ie s cr ea te as m a n y pr ob le m -' , as th ey ~ o lv e. ( . , . , . , . ) . o v e r th e il ex t iw en ty y ea rm .~ ol ar e n er g y lu st c an '! m a k e n lu eh d if fe re n ce in m ee ti n g t h e n at io n 's en er g y n ee d s. ( . , t). o , . , . ) ~ . i su p p o lt )e d e ra l g u vc ln m e n l su b si d ie s fo r th e c o m m e rc ia h z a - fi o n o f ga .~ ol in e m a d e ]r o n l co al a n d ~ ha k" (+ . , . , . i , i . ) . i op po ~ ,c t h e le d er al g u v cr n - n le n f' s pr ol 't {i oh ~) [ i~ iic (c ~i i" p( cw et th ro u g h su b si d ie s an d o th er a d v an ta g es . (+ . , i. i, + . . . ) . e n er g y re se ar ch an d d e' ,+ el o p m cn t .' ~ o u ld e m p h a si z e re n ew ab le en er g y so u rc es li k e so la r ~ n er g y . (+ . , + . , -~ . , + . 'o ) . i d o u 'l k n o w w h o o r w h at to b el ie v e a b o u t th e en er g y s il u a ti o n . (+ . ,+ . , . , (i . ) . b ec au se ih e tr u th a b o u t th e en er g y c li si s is s o c o m p le x , it 's d if li cu h to , ex p la in to t h e p u b li c. ( . , . , . , + . ) ~ a n~ , cl ti ci cn t an d el le ct iv c en er g y p o b c} w il l h a ve to b e d ir ec te d b y t h e fe d er al g o v e rn m e n t. (+ . , . , (} . , . ) in . ] w an l b el ie r in lo rl n a tl o n ab l~ tl l h o w t he : c n e lg y c ri sl ,, ai fe ct ~ , m c a n d m y c o m m u n it y , a n d w h at w e ca n d o a b o u t i[ . + . . . . + l. i, + . ) . i w o u ld li k e io s ee m o re e ll ,a rt b y lh e g < w cr n n ]e n l to s el l it s en er g y p o li cy p ro p o sa ls t,a i h e pu bl i, .'. (+ . , { . , (} . , + . ) -- , l. o. a t h e results are reported in r. d. brunner, "'citizen viewpoints on energy: r i c h m o n d , indiana" ( m a r c h , ). t h e i n d e p e n d e n t estimate was made by the f o r m e r d i r e c t o r o f m a r k e t i n g research, office o f energy c o n s e r v a t i o n a n d e n v i r o n m e n t , federal energy a d m i n i s t r a t i o n . it was based on s t a t e m e n t s in the q-sample that distinguished the three viewpoints and were similar to items that had been included in a number o f national sample surveys s p o n s o r e d by the fea. this analysis i n c o r p o r a t e s p r o p o s i t i o n s f r o m a n u m b e r o f studies o f public o p i n i o n and mass m o v e m e n t s , including several classics: w. l i p p m a n n , public opinion (new york: t h e free press, ed.); h. d. lasswell, psychopathology and politics (new york: viking press, ed.), especially ch. x; h. d. lasswell, world politics and personal insecurity(new york: t h e free press, ed.), especially part iii; and h. d. lasswell and a. kaplan, power a n d s o c i e t y (new tlaven: yale university press, ), especially the c h a p t e r on symbols. f o r a brief analysis o f the interplay o f symbols, conditions, a n d public opinion in the oil embargo, see r. d. brunner, " a n ' i n t e n t i o n a l ' alternative in public opinion research," american journal o f political science, x x i (august, ), pp. - . o n the diversity o f interests a m o n g the policy-making elites see " i n d u s t r y ' s views on the critical choices," new york times(april , ) a n d the n u m e r o u s published critiques o f major presidential energy initiatives such as the n a t i o n a l energy plan i n t r o d u c e d in april . a glimpse o f the politics o f energy policy p l a n n i n g can be f o u n d in l. h. l a p h a m , " t h e energy debacle," harper's (august, ), pp. ff. ideological differences a m q n g energy policy experts are a persistent t h e m e in t h e w o r k o f a. b. lo~ins, particularly "'cost risk benefit assessments in energy policy," george washington university law review, (august, ), pp. . c o m m e n t s on press coverage o f projected natural gas shortages can be found in r. m orris, " w h a t e v e r happened to the natural gas crisis?" columbia journalism review ( m a r c h / a p r i l , ), pp. ff. see also, e. m. kennedy, " f u e l price decontrol is a mistake," challenge ( m a y - j u n e , ), pp. - . s c a p e g o a t i n g is n o t limited to m e m b e r s o f the general public. see j. reston, " w h o ' s to bl~/me?" new york times ( m a y , ), p. e , a n d a letter in response from w. d. b u r n h a m published in the t i m e s ( m a y , ), p. a . c o n s i d e r the following by j, s. milstein, " h o w c o n s u m e r s feel a b o u t eriergy: attitudes and behavior during t h e winter a n d spring o f - " (u.s. d e p a r t m e n t o f energy, june, ), p. : p e o p l e d o not want to pay higher prices for energy because higher energy prices are the p r o b l e m to a majority o f people. higher energy prices are o f great c o n c e r n to people because they are personally experienced weekly and monthly t h r o u g h gasoline and utility bills. thus people are baffled by proposals to solve the energy p r o b l e m by raising energy prices to consumers: h o w can you solve high prices by making t h e m even higher? m o r e precisely, the p r o b l e m is s y m b o l inflation. in parallel with m o n e t a r y inflation, it is a case o f t o o m a n y w o r d s and n u m b e r s chasing t o o few verifiable meanings from the viewpoint o f the "buyer." t h e effect is to render ineffective the principal i n s t r u m e n t o f policy in the s h o r t run, the m a n i p u l a t i o n o f symbols. c o m p a r e mrs. a's c o m m e n t s on the " b o y crying wolf.'" strategy is used here in the sense o f a. m. rivlin: a general principle which, if widely accepted, provides a stable and constructive c o n t e x t for the c o n s i d e r a t i o n o f specific plans designed to implement it. see "social policy: alternative strategies for the federal g o v e r n m e n t " (w. s. w o y t i n s k y lecture no. , institute o f public policy studies a n d d e p a r t m e n t o f economics, t h e university o f michigan, ). a small n u m b e r o f c o m m u n i t i e s a r o u n d the country already have achieved remarkable results t h r o u g h local energy initiatives with very little national publicity. see the hearings on local energy policies, may , j u n e and , , o f the energy and p o w e r s u b c o m m i t t e e , under c h a i r m a n j. d. dingell, c o m m i t t e e on interstate a n d f o r e i g n c o m m e r c e , u.s. h o u s e o f representatives (s erial no. ). a n analysis o f t h e hearings a n d o t h e r sources can be f o u n d in r. d. b r u n n e r ( ), ~'decentralized energy policies," public policy : - . heinz heinemann. the berkeley years ( - ) lawrence berkeley national laboratory lawrence berkeley national laboratory title heinz heinemann. the berkeley years ( - ) permalink https://escholarship.org/uc/item/ c v pg author coble, inger m. publication date - - peer reviewed escholarship.org powered by the california digital library university of california https://escholarship.org/uc/item/ c v pg https://escholarship.org http://www.cdlib.org/ heinz heinemann. the berkeley years ( - ) gabor a. somorjai department of chemistry, university of california, berkeley, ca materials sciences division and chemical sciences division, lawrence berkeley national laboratory, berkeley, ca * to whom correspondence should be addressed. e-mail: somorjai@berkeley.edu. heinz heineman came to berkeley in and stayed there for years. this was the time of the energy crisis and we did not have anybody like him who had such a tremendous industrial experience with oil and coal conversion technology and science. he was interested in the conversion of coal to gaseous molecules and our studies with model catalysts appealed to him and attracted him. in a way, heinz heineman was bigger than life, since he played such a seminal role in the history of american catalysis science. running title: heinemann. the berkeley years keywords: heinemann, catalysis i. introduction catalysis sciences dates back to the ies with vladimir ipatieff, herman pines, eugene houdry, paul emmett, keith hall and hugh taylor, who had established the fundamental phenomena by focusing on motor fuel production by catalytic means, the co hydrogenation reactions, ammonia synthesis and some of the fundamental phenomena that led to the definition of active sites in heterogeneous catalysis. this period was followed by the industrial might of the petroleum industry, vladimir haensel of universal oil products co, jules rabo of union carbide, otto beeck at shell, paul weiss at mobile, john sinfelt at exxon, tom hughes at chevron, and others, who focused on catalytic conversion of fuels to high-octane gasoline and diesel fuels. the presence of a dutch component in american catalysis science was caused by the relocation of much of shell’s research from the netherlands because of the german occupation, to the united states. ii. catalytic research of heinemann in berkeley heinemann (figure ) was an industrial scientist in this very period. after a long period of industrial research with kellogg he moved to mobil and retired from the company just before coming to berkeley. during this period, catalysis science performed so excellently in industry declined and the field moved to centers in academia, and berkeley was one of them. he employed and worked with postdoctoral fellows over a year period who are maintaining their activity even at present. he started to work with graphite as a model carbon solid to study the catalytic gasification using potassium hydroxide as a catalyst[ , ]. he found at relatively low temperature at k hydrocarbons from c to c could be formed with high efficiency as shown in fig. . he worked on the mechanism and found that the carbon bond next to the oh bond of potassium hydroxide had to be broken as the rate limiting step to produce products of co and hydrocarbons. he found other catalysts also worked for carbon gasification at k using mixtures of potassium hydroxide and oxides of transition metals as catalysts[ ]. out of these transition metal mixtures, iron oxide and nickel oxide were the most efficient and had the highest activity. electron microscopy studies revealed that potassium hydroxide alone as a catalyst channeled into the graphite and at the end of the channel the potassium hydroxide dissolved the carbon, which then gasified. when a transition metal was used, both edge recession and channeling into the graphite was observable. following the work with graphite as a model catalyst the steam gasification with chars was studied at temperatures below k using a potassium oxide - calcium oxide catalyst, which shows superior resistance to deactivation by sulfur [ , ]. heinz heinemann in the - period turned then to the conversion of methane by oxydehydrogenation using catalysts such a calcium, nickel or potassium oxides at low temperatures, below °c [ ]. we found catalytic oxidative coupling of methane to produce c and c paraffins and olefins under these circumstances. oxydehydrogenation was the focus of his work for these remaining years in berkeley [ - ]. he pursued that with mechanistic studies using oxygen isotopes to study isotope exchange to reveal the mechanism of oxydehydrogenation and utilized other catalysts such as zsm- zeolites and magnesium lithium oxide catalysts, and the effect of steam [ ]. heinz heinemann left with us a tradition of curiosity, the interest in technology and energy conversion, close scrutiny of experimental data and carrying out seminal studies of kinetics and catalyst structures to understand the fundamental ingredients of catalyst activity and selectivity. he had important influence on the next generation of researchers and he played a significant role in the history of catalysis science. acknowledgement this work was supported by the director, office of science, office of advanced scientific computing research, office of basic energy sciences, materials sciences and engineering division, chemical sciences, geosciences, and biosciences division, of the u.s. department of energy under contract no. de-ac - ch . references [ ] f. delannay, w. t. tysoe, h. heinemann and g. a. somorjai, carbon , , - . [ ] f. delannay, w. t. tysoe, h. heinemann and g. a. somorjai, applied catalysis , , - . [ ] j. carrazza, w. t. tysoe, h. heinemann and g. a. somorjai, journal of catalysis , , - . [ ] p. pereira, r. csencsits, g. a. somorjai and h. heinemann, journal of catalysis , , - . [ ] p. pereira, s. h. lee, g. a. somorjai and h. heinemann, catalysis letters , , - . [ ] j. rasko, g. a. somorjai and h. heinemann, applied catalysis a-general , , - . [ ] y. f. chang, g. a. somorjai and h. heinemann, journal of catalysis , , - . [ ] y. f. chang, g. a. somorjai and h. heinemann, journal of catalysis , , - . [ ] y. f. chang, g. a. somorjai and h. heinemann, applied catalysis a-general , , - . [ ] y. f. chang, g. a. somorjai and h. heinemann, journal of catalysis , , - . figure . heinz heinemann figure plot of dependence on reaction time of the proportion of hydrocarbons for a koh/c loading equal to . (mol). 	i. introduction 	ii. catalytic research of heinemann in berkeley 	acknowledgement 	 	[ ] f. delannay, w. t. tysoe, h. heinemann and g. a. somorjai, applied catalysis , , - . 	[ ] p. pereira, r. csencsits, g. a. somorjai and h. heinemann, journal of catalysis , , - . 	[ ] j. rasko, g. a. somorjai and h. heinemann, applied catalysis a-general , , - . 	[ ] y. f. chang, g. a. somorjai and h. heinemann, journal of catalysis , , - . 	[ ] y. f. chang, g. a. somorjai and h. heinemann, journal of catalysis , , - . university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq a controller for pv system using artificial neural network https://doi.org/ . /utq/utj/vol / / assist prof. sadiq muhsin ihmood, ali hameed elaal mechanical engineering dept. college of engineering. university of thi-qar. abstract. in this research, study theory of system includes the use of important source of renewable energy sources (solar source) and linking this system with an electrical load typical (home) using artificial intelligence. the world is witnessing significant rise in fossil fuel prices since the end of the last century until now, this rise in price increases with the decrease in inventory day after day. therefore, turned the attention of researchers in the field of power generation to expand in non-conventional energy sources (new and renewable energy sources). new and renewable energy is inexhaustible energy in use because they rely on renewable natural resources. so in this study find detailed explanation about the system of photovoltaic cells system with solar cell types. the mathematical model is an important part of the detailed study for pv systems. as well as study models for photovoltaic systems via the matlab/simulink, is a programming environment contains many models for renewable systems intended to perform simulation and analysis. solar cells system needs to apply the (mppt) algorithm due to the instability of external circumstances such as solar radiation and temperature. therefore, a neural network technology applied to train solar cell data is intended to perform the optimization process and get the greatest value for electric power. at the end of this research, study conducted the operation of pv system for processing load appropriate electricity around the clock. where the system simulation with the analysis of the results within hours. simulation results showed that the response of the neural mppt algorithm was faster than the classical p&o algorithm. moreover, the average tracking efficiency of the neural network algorithm was higher than the classical p&o algorithm. https://jutq.utq.edu.iq/index.php/main https://doi.org/ . /utq/utj/vol / / university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq keywords: maximum power point tracking algorithms (mppt), pv _array, photovoltaic (pv) modelling, neural network simulink modeling. الخالصة في هذا البحث أجريت دراسة نظرية لنظام شمسي يتضمن استخدام مصدر مهم من مصادر الطاقة المتجددة )مصدر الشمس( وربط هذا النظام مع حمل نموذجي )منزل( باستخدام الذكاء االصطناعي. يشهد العالم ارتفاعا ملحوظا في أسعار الوقود االحفوري منذ نهاية القرن الماضي وحتى االن، حيث يزداد هذا االرتفاع والتناقص في المخزون يوما بعد يوم. ولهذا فقد اتجهت انظار الباحثين في مجال توليد القدرة الكهربائية الى التوسع في استغالل مصادر الطاقة الغير تقليدية بصورة خاصة مصادر التي ال تنضب باالستخدام الطاقة الجديدة والمتجددة. تعتبر الطاقة الجديدة والمتجددة من أنواع الطاقة ألنها تعتمد على مصادر طبيعية متجددة .حيث تناولت الدراسة في هذا البحث شرح مفصل عن طاقة الشمس مع التطرق الى أنواع الخاليا الشمسية .النموذج الرياضي يعتبر جزءا مهما من الدراسة بنظام الخاليا الضوئية التفصيلية الخاصة باألنظمة الشمسية .كذلك دراسة النماذج الخاصة )الشمسية(عن طريق بيئة )الماتالب/سميولنك(التي هي عبارة عن بيئة برمجية الكترونية تحتوي على العديد من النماذج الخاصة باألنظمة المتجددة الغرض منها هو اجراء المحاكاة والتحليل للنتائج. نظام لك نتيجة لعدم استقرار الظروف الخارجية مثل الخاليا الشمسية يحتاج الى تطبيق خوارزميات ذكية وذ مستوى االشعاع الشمسي ودرجة الحرارة. لذلك تم تطبيق تقنية الشبكات العصبية التي تعتمد على التيار( الغرض منها هو اجراء عملية -اجراء التدريب للبيانات الخاصة بنظام الخاليا الشمسية )الفولتية للقدرة الكهربائية. في نهاية الدراسة يتم تشغيل نظام الخاليا التحسين. والحصول على أعظم قيمة الشمسية مع اجراء عملية السيطرة على النظام الشمسي من اجل تجهيز الحمل بالطاقة الكهربائية ساعة. بالمقارنة مع المناسبة على مدار الساعة. حيث تجرى محاكاة للنظام مع تحليل النتائج خالل . النتائج وأثبتت بانها نتائج دقيقة خرى تم التحقق من صحةنتائج االبحاث األ nomenclature v cell output current, cell output voltage, a, v. ,i 𝑰𝒑𝒉, 𝑰𝒅, the photocurrent, the diode current, 𝑰𝒐 the saturated reverse current or leakage current , a. tc, ta cell operating temperature, ambient air temperature, k tr reference cell operating temperature= c = . k. 𝐍𝐬, 𝐍𝐏 number of series cells, number of parallel cells. https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq 𝐑𝐬𝐡 ، 𝐑𝐬 shunt resistance ، series resistance Ω. 𝐈𝐩𝐡, the photovoltaic current at tc& g, a. 𝐈𝐨, reverse saturation current at tc, a. g the intensity of solar irradiance, w/m . gr the reference intensity of solar irradiance = w/m . ki temperature coefficient of the short-circuit current. kₒ temperature coefficient of the open circuit voltage. q electron charge ( . × − c. k boltzmann constant ( . x − j/k. a the diode ideality factor. vt thermal voltage. ip current leak in parallel resistor. a. eg band-gap of the semiconductor material. - introduction: every country in the world needs to develop its resources and policies, as this development related to energy, keeping in mind the environmental pollutants. the purpose is to better plan for the future [ ]. if using traditional energy sources such as fossil fuels, there is, an important fact is the growing energy consumption significantly related to carbon dioxide emissions. the increase in the rate of emissions as well as the global warming has a close relationship with developments on energy sources. energy sources especially electric energy sources in many countries is the main motivation for agriculture and industry. energy development is the main measure of power as well as the level of development in the future. the use of new and renewable sources of energy in the countries of the world whose purpose is to avoid problems caused by dependence on fossil fuels because they are exhaustible sources as they are considered non-environmentally friendly.[ ] however, non-renewable sources are always non-sustainable sources. an example of this is the energy crisis that occurred in in parts of the world due to lack of fuel, where people are faced with many problems. the oil embargo was found in march . despite the oil embargo found that, oil prices remain high and this increase was the impact on the continuing energy crisis throughout this century. in the period - , there were some laws imposed to rationalize energy consumption, including: price controls, rationing of gasoline, reduce speed, and extinguish the lights during the day. all these laws were imposed because of the crisis-taking place in the energy. https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq there are many reasons that led to the rapid spread of technologies of new and renewable energy across the countries of the most important of these reasons are:[ ]. -climate changes. -rising fossil fuel prices. -increased air pollution as a result of traditional energy sources. -lack of processing power. an important example of the use of renewable energy technology is certified for emissions of carbon dioxide gas in the following countries: iran, iraq, and saudi arabia from to , respectively, where the percentage of increase in emissions as follows: . %, . % and . %. although these countries have been able to use renewable energy. where there are recognized scheme through which the rates of increase and decrease emissions of carbon dioxide gas in the middle east and north africa regions from to . [ ]. . -photovoltaic (pv) energy. photovoltaic energy is energy obtained from sunlight. through the system of photovoltaic cells that directly convert solar radiation into electricity. photovoltaic cell has the primary role in this conversion process. set of photovoltaic cells connected together called panel. in general, panels are a number of solar cells linked to form a series cells for getting high voltage. either for the purpose getting high currents, this is done by increasing the surface area of cells or by connecting cells in parallel. photovoltaic system consists of one or more panel; they are connecting to either parallel or a series. photovoltaic system consists of five major components: .ac filter ـdigital controller. ـinverter. ـdc-dc converter. ـpv array. ـ [ ] . -intelligent mppt techniques: recently appeared a group of smart techniques. these techniques are described as smart, because it is a simulation of the human mind. several researchers have clarified these techniques, where they use computational techniques in control units to reach the maximum power point (mpp), quick response, reduce oscillations occurring in the power curve in pv system. . . - neural network technique: https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq neural network technology has become commonly used in non-linear systems. the difficult problems in modelling systems was solved by neural networks using parameters approximations. neural network consists of three layers: input layer, hidden layer, and output layer. input layer consists of neurons; feed this layer by two-variable voltages and current. which they obtained from the photovoltaic system. the output of the neural network is a duty cycle, which is used to drive the converters operated at or near the mpp. hidden layer used to distribute signals input to output layer; this is based on the transfer function. there is no accurate calculation to determine how many neurons in the hidden layer. select number of neurons through a trial and error. there are also multiple formulas for transfer function. they are tangent sigmoidal function used in hidden layer and pure linear function used at output layer. the advantages of neural networks in creating the mpp is that train these networks equipped high and accurate electrical point without the need of great knowledge about the determinants of photovoltaic system. [ ] [ ] [ ]. figure : neural network technique based on mppt. [ ] -mathematical modeling of photovoltaic system. study of solar photovoltaic cells model using electric circuit equations for solar cell. take into consideration the effect of solar radiation and temperature changes. solar cell's circuit consists of a photoelectric current source connected in parallel with a diode, series electrical resistance (rs) and electrical resistance in parallel (rp). photocurrent source generates a constant value for the current proportion, with the intensity of solar radiation that falls directly on the surface of the solar cell. the external conditions of the weather, have a significant impact on photovoltaic systems, among these conditions is the https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq level of solar radiation and temperature. the amount of electric power produced, price, location and design of those systems all rely on external work conditions. therefore, must focus on precision and performance study for those systems, because they operate under variable conditions. the relationship between voltages and current (i-v) is the basis for the study and analysis of solar photovoltaic cell system. then put the appropriate control method, which adapt these systems with changing conditions. diode equivalent circuit of a solar cell is necessary to determine the characteristics of the current-voltage curve. according to the shockley equation, the voltages increase logarithmically, in the case of an open circuit. diode current is directly proportional to the saturation current [ ] [ ] [ ] [ ] [ ] [ ]. id = io, cell ∗ exp [( q v a k tc )− ] … … . . … . ( ) vt = k ∗ tc q ∗ ns … … … … … . . … . . … . ( ) i = iph, cell − id − ip … … … … . … … … … … … … … … … … … . … . ( ) i = iph, cell − io, cell ∗ e [( q( v+i rs) a k tc )− ] − [ v + irs rsh ] … … … … … . ( ) v = a k tc q ln[ iph, cell + io, cell − i io, cell ] − i rs … … … … … … … … . . ( ) iph, cell = g gr [iphr + ki ∗ (tc − tr)] … … … … … … … … … . . … … . ( ) io, cell = [ior ∗ ( tc tr ) ] ∗ e [ q eg a k ∗( tr − tc ) ] … … … … … … … . … … … . ( ) https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq main parameters of solar cells can be enumerated as follows: [ ] -short circuit current (isc). - open circuit voltage (voc). -maximum power point (mpp). -efficiency of solar cell and fill factor. pmax = vmax * imax……………………………………………. ( ) η = pmax pin ∗ … … … … … … … … … … … … … … … … … … … … … ( ) pin = g ∗ asur … … … … … … … … … … … … … … … … … … … … . . ( ) ff = pmax voc ∗ isc … … … … … … … … … … … … … … … … … … … . . … ( ) . simulink modeling of photovoltaic (pv) system. a -kw pv array is connected to a -kv grid via a dc-dc boost converter and a three-phase three-level voltage source converter (vsc). maximum power point tracking (mppt) is implemented in the boost converter by means of a simulink model using the ' neural network ' technique. the average model contains: -pv array delivering a maximum power of ( kw) at ( w/m ) sun irradiance. - average model of boost converter increasing voltage to v dc. - mppt controller use the “neural network” technique.it connect with average model of boost converter. https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq -average model of vsc. the vsc converts the v dc to v ac and keeps unity power factor. - -kvar capacitor bank filtering harmonics produced by vsc. - -kva v/ kv three-phase coupling transformer. -utility grid model ( -kv distribution feeder + kv equivalent transmission system).[ ] figure : photovoltaic system simulink modeling (pv array (average model)). . - neural network simulink modeling. the function gensim generates block descriptions of networks so you can simulate them using simulink ® software. gensim(net,st) the second argument to gensim determines the sample time, which is normally chosen to be some positive real value. if a network has no delays associated with its input weights or layer weights, this value can be set to - . a value of - causes gensim to generate a network with continuous sampling. the input blocks are actually a standard constants blocks. https://jutq.utq.edu.iq/index.php/main file:///j:/matlab/matlab% production% server/r a/help/nnet/ref/gensim.html university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq figure : deploy neural network simulink diagrams. [the math works, inc., matlab r b]. . results: by using simulink models of pv array and neural network and implemented this models the result display as shown in figure [ , , , , , , , , , and ] below: the -kw pv array of the detailed model uses sunpower modules (spr- ). the array consists of strings of series-connected modules connected in parallel ( * * . w= . kw). open the pv-array block menu and look at model parameters. manufacturer specifications for one module are:  number of series-connected cells:  open-circuit voltage: voc= . v  short-circuit current: isc = . a  voltage and current at maximum power: vmp = . v, imp= . a the pv array block menu allows you to plot the i-v and p-v characteristics for one module and for the whole array. the characteristics of https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq the sunpower-spr array are reproduced below [ ]. figure : i-v and p-v characteristics of the pv array modules show ish, voc, imp, vmp, and mppt. to validate the results of the solar cell model, the results are compared with the results obtained from ref. [ ]. these comparisons are shown in figures , , , and . figure ( ) showing the relationship between i-v under the influence of different radiation values ( , , , w/m^ ) for one module only. so this figure ( ) compares with the figure ( ) for one module too under same conditions. https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq figure : i-v characteristics of pv array with varying solar irradiance level of one module [antonio faggio ] [ ]. figure : i-v characteristics of pv array with varying solar irradiance level of one module. https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq figure : i-v and p-v characteristics of pv array with varying solar irradiance level of series modules; parallel strings [antonio faggio ] [ ]. figure : i-v and p-v characteristics of pv array with varying solar irradiance level. https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq figure : i-v and p-v characteristics with varying operating temperature. figure a: duty cycle of mppt controller figure b: duty cycle of mppt using perturb & observe technique. controller using neural network. https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq figure : errors values of neural network. figure : the regression of neural network. t a rg e t y r= . fit ………. y=t https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq figure : power curve simulation result within hours. -discussions. using the matlab program, specifically the simulink model was implemented the pv array that is addressed in the section simulink modeling. there are several types of models the pv array. in this research was selected one of these models is sunpower spr- e-wht-d. parameters for this model are shown in the dialog box and parameters of pv array. when an implementation of the model via matlab/simulink, there are three important variables represent the output of the model for pv array, voltages, current and power. where the focus is on the non-linear relationship between (current-voltage) and (power- voltages) (the i-v and p-v characteristics). study of the solar model results are first and second case, the first case is to be constant temperature ( c) with solar radiation level changes. the second case is the temperature change with a constant level of solar radiation ( w/m^ ). the i-v and p-v characteristics are shown in figures ( , , , and ). curves of the solar model featuring non-linear nature. the output current and power of pv cell depend on the cell’s terminal operating voltage and temperature, and solar radiation. perturb & observe neural network https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq  i-v and p-v characteristics with varying solar radiation level fig. , , it is observed that with the increase of the solar radiation, the short-circuit current of the pv module increases and the maximum power output increase.  i-v and p-v characteristics with varying operating temperature fig. , it is observed that with the increase of the operating temperature, the short-circuit current of the pv module increases. however, the maximum power output decrease.  the reason is the open-circuit voltage is logarithmically dependent on the solar irradiance, yet the short-circuit current is directly proportional to the radiant intensity. neural network architecture is very important to find the right solution for complex systems with non-linear relations or which owns random variable. the training process is the basis for the neural network. there are multiple algorithms to perform the training process but the famous type of the back propagation (or feed-forward), it is widely used. the simplest form of neural network is using architecture consists of three layers. input layer receives external data, hidden layer receive data from input layer and sent to the output layer. training through the back propagation based on two main points: learning and knowledge. this research was applied by the use of tan- sigmoid function as an activation function in order to calculate the hidden layer output and a linear function to calculate the output. figure ( ) shows the curve for electric power data produced from solar cells but different control methods. the curve on the right represents the power curve using a smart algorithm neural network technology; the purpose is to reach and stability at maximum power, either the curve on the left is the power curve using the classic algorithm perturb & observe (p & o. instability in power value led to use maximum power point tracking (mppt). the other target of figure ( ) is validated using neural network technique through comparison with classical algorithm (p &o) adopted in most published research. simulation results showed that the response of the neural mppt algorithm was faster than the classical p&o algorithm. moreover, the average tracking efficiency of the neural network algorithm was higher than the classical p&o algorithm. . conclusions: https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq the detailed study of the pv system led to access a number of necessary conclusions: - relying on new and renewable sources of energy as successful alternative sources. renewable energy sources (solar source) provide sufficient electrical energy without causing environmental pollution with the possibility of not being depleted as they emanate from sources of nature. - modern techniques like neural network used in control of new and renewable energy systems has led to excellent results, like getting the maximum value for the electrical power. - easily handle with the results of implementation of pv system model, as a result of the use of the environment (matlab/simulink) that contain many systems and electronic means which help to deal with the smooth systems. - dealing with the modern electronic control led to convenience in operation of the pv systems, which reduced operational cost. - neural networks are characterized by fast tracking for maximum power value with neglecting oscillations. - neural network performance is not affected by variation load, noticing a slight variation, and during a few time reach to mpp point. - high smoothness is a salient feature of neural network simulation on during execution in the electric power curve, as opposed to using the classic technique (p @ o) known as frequent oscillation and slow in response. references: [ ]- payam nejat , abdul kasir morsoni , fatemeh jomehzadeh , hamid behzad , mohamad saeed vesali , m.z.abd.majid. iran’s achievements in renewable energy during fourth development program in comparison with global trend, renewable and sustainable energy reviews , ( );vol : – . https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq [ ]-omid nematollahi, hadi hoghooghi, mehdi rasti , ahmad sedaghat, "energy demands and renewable energy resources in the middle east”, renewable and sustainable energy reviews, ( ); vol : – . [ ]- bob vander zwaan, lachlan cameron, tom kober, potential for renewable energy jobs in the middle east, energy policy ( );vol : – . [ ]- the world bank. available from: 〈http://data.worldbank.org/indicator/en. atm.co e.pc〉. [ ]-cemal zeray. renewable energy sources. institute of natural and applied sciences. department of electrical electronic engineering. january , pages . [ ]-s. saravanan, ramesh babu n. maximum power point tracking algorithms for photovoltaic system – a review. renewable and sustainable energy reviews ( ).vol . – . [ ]- f. chekired , a. mellit , s.a. kalogirou , c. larbes , intelligent maximum power point trackers for photovoltaic applications using fpga chip: a comparative study, solar energy ( ); vol : – . [ ]- bidyadhar subudhi, raseswari pradhan, a comparative study on maximum power point tracking techniques for photovoltaic power systems, ieee transactions on sustainable energy, january ( );vol. : no. . [ ]- trishan esram, comparison of photovoltaic array maximum power [ ]- m.b. eteiba, e.t. el shenawy, j.h. shazly, a.z. hafez. a photovoltaic (cell, module, array) simulation and monitoring model using matlab®/gui interface. international journal of computer applications. – no. , (may ); volume : ( – ). [ ]- Şaban yılmaz, hasan rıza Özçalık, mahit güneş, osman doğmuş. mathematical model derivation of solar cell by using onediode equivalent circuit via simulink. international journal of education and research. (december ); vol. :no. . [ ]- g.joga rao, dr. d.k.mangal, dr.s.k. shrivastava, md.gouse baig. modeling and simulation of incremental conductance maximum power point tracking (mppt) algorithm for solar pv array using boost converter. engineering and technology. ( ); volume : issue | print issn: - | online issn: - . https://jutq.utq.edu.iq/index.php/main university of thi-qar journal vol. no. dec web site: https://jutq.utq.edu.iq/index.php/main email: journal@jutq.utq.edu.iq [ ]- s. sheik mohammed. modeling and simulation of photovoltaic module using matlab/simulink. international journal of chemical and environmental engineering. (october ); volume : no. . [ ]- habbati bellia, ramdani youcef, moulay fatima. a detailed modeling of photovoltaic module using matlab. nriag journal of astronomy and geophysics.( june ) ;volume :pages – . [ ]-huan-liang tsai, ci-siang tu, and yi-jie su, member, iaeng. development of generalized photovoltaic model using matlab/simulink. proceedings of the world congress on engineering and computer science. ( ); isbn: - - - - . [ ]- pierre giroux, gilbert sybille, hydro-quebec research institute (ireq) carlos osorio, shripad chandrachood, the mathworks ( ). [ ]- antonio faggio, hierarchical control of a dc low voltage microgrid supplied by distributed energy resources, thesis submitted for examination for the degree of master of, politecnico di milano, school of industrial engineering and information master of science in electrical engineering, academic year - , page . https://jutq.utq.edu.iq/index.php/main seminar hall automation using microcontroller seminar hall automation using microcontroller bhusare gayatri , zade mohini , pawar yograni , mr. kiran p. varade be student, department of electrical engineering svit college of engineering chincholi nashik maharashtra india association professor department of electrical engineering chincholi nashik maharashtra india. abstract – in seminar hall automation system different system technologies are employed for conservation of electricity. electricity is one of the most important resources int this century. we should conserve electricity otherwise next generation may have to live without electricity but many times we can forgot to turn off the lights and fans when we comes outsides the hall. and thus electricity is wasted. also in most of the cases switches of the light and fan are located inside the room and so have to search them in darkness. to overcome this issue and for conservation of electricity we planned a project in two parts. first one is “person counter” and other one is “automatic room light & temperature controller with a temperature & light intensity display “. the st part is to count the no of person/ visitors entering or leaving the hall & it display on the lcd. from this we decide the no. of seats remaining in large room like seminar hall ; conference hall etc. when the no person enter the room is zero then power supply inside the room the system automatically measures the room temperature ; light intensity ; automatic on/off the fan inside the room . during day time lights not be operated & during cold season fan may not be operated. this efforts lcd also display temperature and light intensity. key words: automation, person counter, traic, pic . introduction energy crisis is the main problem that we facing nowadays. so the conservation of energy is relevant in this occasion .th main objectives of this project is to overcome this problem. this project has parts. the first is “person counter “and the one is an “automatic room light and temperature controller with the increase in standard of living, there is a need for developing technique that would ease the involution of life. the temperature and light intensity in the room is sensed and with respect to that, light and fan in the room is switched on/off when a person enters/ leaves the room. the circuits consists of ir transmitter and receiver leds which are used to sense the entering or leaving of a person to or from the room. the temperature sensor measures the temperature inside the room and analog signal from the sensor is processed by the microcontroller. likewise the light dependent resisters (ldr) generates the analog signals proportional to the available light inside the room. this signal is also processed by microcontroller. whenever the person leaves the room, light and fan will switched off. the speed of the fan and brightness of the light is controlled accordingly. the circuits which we have designed is simple and compact. this project is a microcontroller based room automation. the total number of person inside the room is also displayed on the seven segment display. . definition automation means a technology that performed various procedure this procedure required minimum human contribution. automation has been achieved by various way like mechanical, hydraulic, electrical, and electronics etc. can complete the task where a high degree of accuracy is required. the way of automation work that contains higher production band and also increased productivity and more efficient use of material, civilize product, improved rescue, less workweeks for labors, worker safety is important in automation. the use of largely automatic equipment in system of manufacturing or other production process. simply put robotic process automatic (rpa) is the process of automatic your current work flows so any of your work flow that you have, probably can automate. it’s a technology that controls all the process with the help of automation means using the various electronics devices that help in reducing the human work. also a mechanical devices are operated electronically and that function are done automatic without giving a continuous input from an worker this process or procedure of automating. . aim of project energy conservation is the need for future. today’s world energy crisis is the main problem that we are facing. the aim of this project is to solve this problem and save the energy and it also reduced the human efforts with the help of automation. . block diagram & discription in this project an automatic room light & fan system is develop using microcontroller. the main component of the project is ir sensors and we have used to them of the placement of the sensors is important as it will determining the functioning of the project. these ir sensors are connected to the microcontroller. controller count the person entering and leaving the room. lcd is used to display the number of persons in the hall. the power supply is required is provided by either solar panel or by using wind mills. battery is provided in between solar panel and supply. the required energy is stored in battery which is used by power supply whenever required. power supply device driver ir sensor motor driver ir sensor micro controller fan fan light light lcd x solar panel battery wm fig - : block diagram international journal of engineering research & technology (ijert) issn: - http://www.ijert.org ijertv is (this work is licensed under a creative commons attribution . international license.) published by : www.ijert.org vol. issue , june- www.ijert.org www.ijert.org www.ijert.org a. main components & discription • pic controller • display/lcd • sensors • power supply • dc motor • device drivers . pic controller microcontroller pic f essentially consist of timers, counters, and input/output ports, analog to digital converters (adc). the components like ir sensors, lm , lcd display are connected to the controller. controller count the person in and out to the room and display on lcd. fig - : pic diagram . lcd lcd means liquid crystal display we use this device because of it’s a technology that display on screen this is generally used in laptop computer screen, and also mobiles, tvs, video games also. fig - : lcd diagram . . temperature sensor lm temperature sensors are used in this experiment. lm ic is used as the temperature sensor. it consist of three pins. for every degree variation in the room temperature, there will be a variation in the output voltages of this ic. this analog signal output will be given to the microcontroller for further processing and controlling. the room temperature will be display in the lcd. fig - : temperature sensor . . ir sensor ir sensors used as input circuit. one ir sensor pair is fitted on in door and one is fitted on our door. these ir sensor will check the persons coming in and out of the hall. these are connected to the microcontroller. controller counts the in person and the out persons. fig - : ir sensor . conclusions this project is work on the seminar hall automation. in this system the energy consumption is developed. user comes into the hall or leaves the hall the lights and fans are automatically on/off user can reduce their electricity bill. this system is easy to operate and control. and also a cost effective system. we can implemented this system in malls, schools etc. it reduces the human efforts. for future scope we can add camera to the system. acknowledgement i feel great pleasure to present the dissertation entitled as “seminar hall automation using microcontroller” but it would be unfair on our part if we do not acknowledge efforts of some of the people, without the support of whom this work would not have been a success. very first i am greatly to my respected project guide mr. kiran p varade assistant professor of electrical engineering department for permitting me to use the all available facilities foe successful work od dissertation. i would like to express my sincere gratitude to respected prof. nadeem b shaikh, hod of electrical engineering department, & dr. mukesh k kumawat project coordinator & prof. (dr). y. r. kharde principal of svit, chincholi for finding out time and helping me in this project work. i am also thankful to all teaching and non-teaching staff member of electrical engineering department who has helped me directly or indirectly during this work. last but not least i wish to express my gratitude to my loving parents and friends and all well-wishers for their moral support during completion of this project work. international journal of engineering research & technology (ijert) issn: - http://www.ijert.org ijertv is (this work is licensed under a creative commons attribution . international license.) published by : www.ijert.org vol. issue , june- www.ijert.org www.ijert.org www.ijert.org to references [ ] ying-wen bai and yi- te ku, “automatic room light intensity detection and control using a microprocessor and light sensors”, ieee transactions on consumers electronics, vol. . no. , augest [ ] yong tae park, pranesh sthapit, jae-young pyun, “smart digital door lock for the homae automation”, september [ ] jonh-paul h. knauus, cheri warren, dave kearns, “an innovativr approach to smart automation testing at national grid”, ieee, may, biographies bhusare gayatri s. u.g. student, electrical engineering svit, nashik, maharashtra, india. zade mohini b. u.g. student, electrical engineering svit, nashik, maharashtra, india. pawar yograni a. u.g. student, electrical engineering svit, nashik, maharashtra, india. prof. kiran p. varade, assistant professor of electrical engineering dept., svit, nashik, maharashtra, india. international journal of engineering research & technology (ijert) issn: - http://www.ijert.org ijertv is (this work is licensed under a creative commons attribution . international license.) published by : www.ijert.org vol. issue , june- www.ijert.org www.ijert.org www.ijert.org investigation on humidified gas turbine cycles with maisotsenko-cycle-based air saturator investigation on humidified gas turbine cycles with maisotsenko-cycle-based air saturator guangya, zhu; chow, t. t.; fong, k. f.; lee, c. k. published in: energy procedia published: / / document version: final published version, also known as publisher’s pdf, publisher’s final version or version of record license: cc by-nc-nd publication record in cityu scholars: go to record published version (doi): . /j.egypro. . . publication details: guangya, z., chow, t. t., fong, k. f., & lee, c. k. ( ). investigation on humidified gas turbine cycles with maisotsenko-cycle-based air saturator. energy procedia, , - . https://doi.org/ . /j.egypro. . . citing this paper please note that where the full-text provided on cityu scholars is the post-print version (also known as accepted author manuscript, peer-reviewed or author final version), it may differ from the final published version. when citing, ensure that you check and use the publisher's definitive version for pagination and other details. general rights copyright for the publications made accessible via the cityu scholars portal is retained by the author(s) and/or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. users may not further distribute the material or use it for any profit-making activity or commercial gain. publisher permission permission for previously published items are in accordance with publisher's 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- f - a - - e ).html https://scholars.cityu.edu.hk/en/publications/investigation-on-humidified-gas-turbine-cycles-with-maisotsenkocyclebased-air-saturator( c fc - f - a - - e ).html https://scholars.cityu.edu.hk/en/journals/energy-procedia(db ff fe- b - -b a- aa daeb )/publications.html https://doi.org/ . /j.egypro. . . sciencedirect available online at www.sciencedirect.comavailable online at www.sciencedirect.com sciencedirect energy procedia ( ) – www.elsevier.com/locate/procedia - © the authors. published by elsevier ltd. peer-review under responsibility of the scientific committee of the th international symposium on district heating and cooling. the th international symposium on district heating and cooling assessing the feasibility of using the heat demand-outdoor temperature function for a long-term district heat demand forecast i. andrića,b,c*, a. pinaa, p. ferrãoa, j. fournierb., b. lacarrièrec, o. le correc ain+ center for innovation, technology and policy research - instituto superior técnico, av. rovisco pais , - lisbon, portugal bveolia recherche & innovation, avenue dreyfous daniel, limay, france cdépartement systèmes Énergétiques et environnement - imt atlantique, rue alfred kastler, nantes, france abstract district heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. these systems require high investments which are returned through the heat sales. due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. the main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand forecast. the district of alvalade, located in lisbon (portugal), was used as a case study. the district is consisted of buildings that vary in both construction period and typology. three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). to estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. the results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than % for all weather scenarios considered). however, after introducing renovation scenarios, the error value increased up to . % (depending on the weather and renovation scenarios combination considered). the value of slope coefficient increased on average within the range of . % up to % per decade, that corresponds to the decrease in the number of heating hours of - h during the heating season (depending on the combination of weather and renovation scenarios considered). on the other hand, function intercept increased for . - . % per decade (depending on the coupled scenarios). the values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. © the authors. published by elsevier ltd. peer-review under responsibility of the scientific committee of the th international symposium on district heating and cooling. keywords: heat demand; forecast; climate change energy procedia ( ) – - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /) peer-review under responsibility of the scientific committee of icae – the th international conference on applied energy. . /j.egypro. . . . /j.egypro. . . © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /) peer-review under responsibility of the scientific committee of icae – the th international conference on applied energy. - available online at www.sciencedirect.com sciencedirect energy procedia ( ) – www.elsevier.com/locate/procedia - copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the th international conference on applied energy (icae ). th international conference on applied energy (icae ), - august , hong kong, china investigation on humidified gas turbine cycles with maisotsenko- cycle-based air saturator zhu guangyaa,b, t. t. chowa , k.f. fonga and c. k. leea* adivision of building science and technology, city university of hong kong, hong kong sar, china bdepartment of architecture and civil engineering, city university of hong kong, hong kong sar, china abstract the urge for more energy-efficient power plant systems triggered the design for more advanced power cycle designs. the current simple cycle gas turbine shows its advantage on cost but does not fully exploit the energy available in the flue gas. in this paper, two more efficient humidified gas turbine cycles were investigated. type was a hybrid design which combined an indirect evaporative cooler with a maisotsenko cycle and type a conventional indirect evaporative cooler as air saturator. the simulation results indicated how the operating conditions such as pressure ratio and air flow changed with the designs. both humidified gas turbine cycle systems offered better system efficiencies than a conventional gas turbine system with recuperator and the application of maisotsenko cycle based air saturator could further improve the gas turbine cycle efficiency. parametric studies were also conducted which highlighted the effects of water injection rate and part-load ratio on the comparative performances of the different humidified gas turbine cycle designs. copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the th international conference on applied energy (icae ). keywords: humidified gas turbine cycle, air saturator, indirect evaporator cooler, maisotsenko cycle . introduction with the galloping growth of population and standard of modern life, the energy crisis becomes a serious challenge in our century. in response to the environmental concern, the application of more renewable technologies to enhance the energy supply is one solution. however, the low efficiency and the intermittent energy generation as * corresponding author. tel.: + - ; fax: + - . e-mail address: chunklee@cityu.edu.hk available online at www.sciencedirect.com sciencedirect energy procedia ( ) – www.elsevier.com/locate/procedia - copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the th international conference on applied energy (icae ). th international conference on applied energy (icae ), - august , hong kong, china investigation on humidified gas turbine cycles with maisotsenko- cycle-based air saturator zhu guangyaa,b, t. t. chowa , k.f. fonga and c. k. leea* adivision of building science and technology, city university of hong kong, hong kong sar, china bdepartment of architecture and civil engineering, city university of hong kong, hong kong sar, china abstract the urge for more energy-efficient power plant systems triggered the design for more advanced power cycle designs. the current simple cycle gas turbine shows its advantage on cost but does not fully exploit the energy available in the flue gas. in this paper, two more efficient humidified gas turbine cycles were investigated. type was a hybrid design which combined an indirect evaporative cooler with a maisotsenko cycle and type a conventional indirect evaporative cooler as air saturator. the simulation results indicated how the operating conditions such as pressure ratio and air flow changed with the designs. both humidified gas turbine cycle systems offered better system efficiencies than a conventional gas turbine system with recuperator and the application of maisotsenko cycle based air saturator could further improve the gas turbine cycle efficiency. parametric studies were also conducted which highlighted the effects of water injection rate and part-load ratio on the comparative performances of the different humidified gas turbine cycle designs. copyright © elsevier ltd. all rights reserved. selection and peer-review under responsibility of the scientific committee of the th international conference on applied energy (icae ). keywords: humidified gas turbine cycle, air saturator, indirect evaporator cooler, maisotsenko cycle . introduction with the galloping growth of population and standard of modern life, the energy crisis becomes a serious challenge in our century. in response to the environmental concern, the application of more renewable technologies to enhance the energy supply is one solution. however, the low efficiency and the intermittent energy generation as * corresponding author. tel.: + - ; fax: + - . e-mail address: chunklee@cityu.edu.hk http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf zhu guangya et al. / energy procedia ( ) – author name / energy procedia ( ) – well as high initial cost and geographic requirement hinder the wide application of these kinds of technologies at present. another more direct solution is to improve the efficiency of the power generation system [ ]. gas turbine application is important for the power generation industry. it usually consists of four parts: compressor, combustion chamber (cc), turbine and generator (g) and operates as a simple brayton cycle. the traditional gas turbine power generation system efficiency was low at the early stage, but with the increasing of turbine inlet temperature and pressure ratio, its performance was improved [ ]. coupled with its lower capital cost, shorter start-up time, and lower maintains cost [ ], gas turbine showed its advantage as power supply techniques. however, the simple gas turbine cycle efficiency remain inadequate to extent its application area. in order to exploit the gas turbine advantage, the humidified gas turbine cycle which utilizes an air-water mixture as the working fluid was proposed [ ]. the humidified gas turbine cycle is a promising technology which not only improves the power generation of gas turbine but also reduces the nox emission levels in the combustion chamber [ ]. one of recently proposed humidified gas turbine cycles was the maisotsenko combustion turbine cycle (mctc) developed by a r&d firm based in arvada, colorado [ ]. in the mctc, the humidification tower, after cooler, recuperator, and economizer were combined into one component called air saturator which offered more economical advantages [ ]. the flue gas could be cooled to a lower temperature by applying a high efficiency air saturator which was composed of a conventional indirect evaporator cooler at the top and a maisotsenko cycle (m-cycle) at the bottom. another claimed significant advantage of the mctc was that the air temperature and humidity ratio at the air saturator outlet could be controlled by adjusting the quantity and location of water entering the shell side of the upper part. currently, constant dew-point or wet-bulb efficiencies were employed in the simulation which might not reflect the real performance of mctc under different conditions [ ]. therefore, a revised model for the mctc was presented in this paper which took the dew-point and wet-bulb efficiencies variations into account to reveal its real potentials. besides, mctc with different air saturator designs were compared based on the same compressor, turbine and combustion chamber characteristics to test their influence on system efficiency. finally, some critical parameters which affected the mctc performance were studied. nomenclature h specific enthalpy (kj/kg) lhv lower heating value (kj/kg) ṁ mass flow rate (kg/s) t temperature (k) w electrical power output (kw) effectiveness η efficiency subscript .. state point in the system a air cc combustion chamber dew dew-point temperature f fuel net overall system w water wbt wet-bulb temperature . system configuration simple gas turbine cycle with recuperator (sgtr) was used as reference system in this paper. fig. a shows the layout of the sgtr. compared to the simple brayton cycle, a recuperator was added to recover part of the heat from the exhaust gas to pre-heat the compressed air before entering the combustion chamber. in this way, the thermal efficiency of the cycle could be increased. fig. b depicts the layout of the mctc according to saghafifar zhu guangya et al. / energy procedia ( ) – author name / energy procedia ( ) – and gadalla [ ]. the air saturator was employed in place of the recuperator in the sgtr. compressed air was driven to the air saturator in which liquid water was added into the air. the preheated and humidified high-pressure air was then fed into the combustion chamber where it was mixed with the fuel for combustion. the generated high- temperature flue gas leaving the combustion chamber was utilized to drive the turbine for power generation. the low-pressure exhaust gas leaving the turbine was delivered back to the air saturator at the upper part to recover the exhaust energy for adding more moisture in the compressed air. to justify if this configuration (type ) was better, another design was also considered which solely employed a conventional indirect evaporator cooler as the air saturator (type ) as shown in fig. c. to derive the mathematical models for the various components in the system, the following assumptions were made:  a constant polytropic efficiency and flow coefficient were assumed for compressor and turbine;  the compression and expansion processes were adiabatic;  all processes were assumed to be steady state;  the air, fuel and exhaust gases were considered to be ideal gases;  the combustion process was complete. a b c fig. . layout of the different gas turbine cycle (a. simple gas turbine cycle with recuperator; b. humidified gas turbine cycles with type air saturator; c. humidified gas turbine cycles with type air saturator) . . compressor and turbine the mathematical model for calculating the compressor specific work, mass flow rate and compressor outlet air temperature could be found in fong and lee [ ]. due to the high turbine inlet temperature setting, turbine blade cooling was needed. in order to cool the blades, part of compressor outlet air was separated then mixed with the combustor exhaust gas in the first blade rows of the turbine. similar to that in [ ], it was assumed that the blade cooling air is mixed with the combustor’s gases before entering the turbine. . . air saturator for the type air saturator, the modelling method similar to that in [ ] was employed. the lower part was a typical counter-flow regenerative heat and mass exchanger. the hot compressed air underwent sensible cooling from state to state (see fig. b) with its performance represented by the dew-point effectiveness (ε𝑑𝑑𝑑𝑑𝑑𝑑) as defined ε𝑑𝑑𝑑𝑑𝑑𝑑 = 𝑇𝑇 −𝑇𝑇 𝑇𝑇 −𝑇𝑇𝑑𝑑𝑑𝑑𝑑𝑑, ( ) the upper part was similar to a typical indirect evaporative cooler. the temperature of the flue gas at state could be estimated from 𝑇𝑇 = 𝑇𝑇 − 𝜀𝜀𝑑𝑑𝑤𝑤𝑤𝑤(𝑇𝑇 − 𝑇𝑇𝑑𝑑𝑤𝑤𝑤𝑤, ) ( ) where 𝜀𝜀𝑑𝑑𝑤𝑤𝑤𝑤 was the wet-bulb effectiveness of the upper channel. type air saturator was similar to the upper part of type . the wet-bulb effectiveness was employed to determine the outlet temperature of the dry channel containing the flue gas so that 𝑇𝑇 = 𝑇𝑇 − 𝜀𝜀𝑑𝑑𝑤𝑤𝑤𝑤(𝑇𝑇 −𝑇𝑇𝑑𝑑𝑤𝑤𝑤𝑤, ) ( ) zhu guangya et al. / energy procedia ( ) – author name / energy procedia ( ) – as we mentioned before, the previous research [ ] was based on the constant dew-point and wet-bulb efficiencies. however, the air saturator dew-point and wet-bulb effectiveness depended on its operation condition and configuration. to investigate, the dew-point effectiveness of the regenerative evaporative cooler as indicated in fig a for the lower channel of type air saturator was calculated based on the same method adopted in another previous study [ ]. the wet-bulb effectiveness employed for the type air saturator and the upper channel of type air saturator was based on the model by wan et al. [ ]. fig. . different evaporative cooler configurations (a. regenerative evaporative cooler; b conventional indirect evaporative cooler) . . combustion chamber the heat transfer across the combustion chamber can be calculated from �̇�𝑚𝑔𝑔, ℎ𝑔𝑔, = 𝜂𝜂𝑐𝑐𝑐𝑐�̇�𝑚𝑓𝑓𝐿𝐿𝐿𝐿𝐿𝐿𝑓𝑓 + �̇�𝑚𝑎𝑎, ℎ𝑎𝑎, ( ) �̇�𝑚𝑔𝑔, = �̇�𝑚𝑓𝑓 + �̇�𝑚𝑎𝑎, ( ) here, cc is the combustion chamber efficiency which takes into account the heat loss to the surrounding. . . overall performance the overall system performance can be calculated from 𝜂𝜂𝑛𝑛𝑛𝑛𝑛𝑛 = 𝑊𝑊𝑛𝑛𝑛𝑛𝑛𝑛 �̇�𝑚𝑓𝑓𝐿𝐿𝐿𝐿𝐿𝐿𝑓𝑓 ( ) where wnet is the system electrical power output and 𝜂𝜂𝑛𝑛𝑛𝑛𝑛𝑛 is the system overall efficiency. . results and discussion table . simulation results comparison for the various gas turbine systems at the reference condition. performance type type sgtr compressor outlet temperature (k) . . . system outlet temperature (k) . . . compressor outlet pressure (kpa) turbine inlet pressure (kpa) compressor mass flow rate (kg/s) . . . turbine mass flow rate (kg/s) . . . fuel mass flow rate (kg/s) . . . compressor specific work input (kj/kg) . . . turbine specific work output (kj/kg) . . . dew-point effectiveness . n/a n/a wet-bulb effectiveness . . n/a system efficiency (%) . . . zhu guangya et al. / energy procedia ( ) – author name / energy procedia ( ) – ef fic ie nc y (% ) water addition rate (kg/s) type type table summarizes the simulation results for the various gas turbine systems at the reference inlet condition (ambient pressure taken as kpa at k and a humidity ratio of . kg/kg) based on the same turbine inlet temperature of k. for the two humidified gas turbine systems, a fixed water injection rate of kg/s was employed. it could be found that the efficiencies of the humidified gas turbine designs were higher than that of the sgtr. this highlighted the strength of air humidification in the enhancement of gas turbine performance. with different types of air saturators, the simulated compression ratios, fuel and turbine mass flow rates varied to some extents. indeed, to reach the same turbine inlet temperature, the resulting fuel injection flow rates and compression ratios for the two humidified gas turbine systems were substantially higher than that of the sgtr. the calculated wet-bulb effectiveness with type air saturator was substantially higher than that with type air saturator. the main reason was that in the type air saturator, nearly % of the injected water was absorbed in the lower channel, i.e. the m-cycle. in other words, the water uptake by the indirect evaporative cooler in the type air saturator was much higher. this cohered with the finding from wan et al. [ ] that the wet-bulb effectiveness decreased with an increase in the water injection rate. to assess the performances characteristic of humidified gas turbine systems, a parametric analysis was carried out to figure out the effect of water injection rate and part-load ratio on the relative performance of the two humidified gas turbine systems. in doing so, all other parameters were kept constant as those in the reference condition except the parameter being investigated. . . water injection rate the major difference of humidified gas turbines over the conventional sgtr was the work fluid and it would be interesting to know how the water injection rate affected the system performance. fig. indicates the results for the different gas turbine systems design. with type air saturator, an optimal water injection rate around the reference value existed in which the system efficiency was maximized over the range of water injection rate analyzed. this could be explained by the fact that an increase in the water injection improved the mass flow to the turbine. however, it also reduced the air temperature entering the combustion chamber. with both opposing effects acted simultaneously, an optimal situation could be expected. the same should also hold with both type air saturator but was not found in fig. . the reason was that the optimal point should likely appear at a very low water injection rate outside the range investigated. nevertheless, the performance difference between the two types of humidified gas turbine systems generally reduced with the water injection rate particularly when it was lower than the optimal value for the type air saturator. fig. . variation of efficiency with water addition rate . . part-load ratio fig. shows the variation of the system efficiency with the part-load ratio of the gas turbine systems. both humidified gas turbine systems performed better than the sgtr especially at a lower part-load ratio. type air saturator showed better performance throughout the whole study range of part-load ratio. meanwhile, the performance discrepancy between type and type air saturators increased a little with the part-load ratio. combined with the previous analysis results made, type air saturator was considered better. zhu guangya et al. / energy procedia ( ) – author name / energy procedia ( ) – . . . . . . . ef fic ie nc y (% ) part-load ratio type mw= . kg/s type mw= . kg/s type mw= . kg/s type mw= . kg/s type mw= . kg/s type mw= . kg/s sgtr fig. . variation of efficiency with part-load ratio . conclusions in this study, the impact of the air saturator performance on a humidified gas turbine cycle was investigated. two types of air saturator designs were considered. type was a hybrid design which combined an indirect evaporative cooler with a maisotsenko cycle, type being a conventional indirect evaporative cooler. performance comparisons were made based on the adoption of the same compressor and turbine characteristics. the simulation results under the reference inlet air condition indicated that both types of humidified gas turbine systems offered higher efficiencies than that based on the conventional gas turbine system with recuperator, with the use of the more complicated type air saturator being better. to further reveal the comparative performances of the two types of humidified gas turbine cycles at different system water injection rate and part-load ratio, a parametric study was conducted. it was found that the performance differences decreased with a lower water injection rate. the impact of the part-load ratio was relatively mild. in view of the simulation results over the ranges of operating parameters investigated, it was concluded that the humidified gas turbine cycles with maisotsenko-cycle-based air saturator was considered better for offering a higher power generation efficiency. acknowledgements the work described in this article was financially supported by the research grants of the city university of hong kong (strategic research project no. and contract research project no. ) references [ ] c.w. chan, j. ling-chin, a.p. roskilly, a review of chemical heat pumps, thermodynamic cycles and thermal energy storage technologies for low grade heat utilization, applied thermal engineering ( ) - . [ ] c. wu. thermodynamic cycles: computer-aided design and optimization, crc press, hoboken, . [ ] s. alfahed, f. alasfour, h. abdulrahim, the effect of elevated inlet air temperature and relative humidity on cogeneration system, international journal of energy research ( ) ( ) – . [ ] m.h. mahmood , m. sultan, t. miyazaki, s. koyama, v.s. maisotsenko, overview of the maisotsenko cycle – a way towards dew point evaporative cooling, renewable and sustainable energy reviews ( ) – . [ ] m. jonsson, j. yan. humidified gas turbines review of proposed and implemented cycles, energy ( ) ( ) – . [ ] v. maisotsenko, l. gillan, t. heaton, a. gillan, power system and method, united states of america patent us b , march, . <http://www.google.com/patents/us >. [ ] m. saghafifar, m. gadalla, analysis of maisotsenko open gas turbine power cycle with a detailed air saturator model, applied energy ( ) - . [ ] k.f. fong, c.k. lee, dynamic performances of trigeneration systems using different prime movers for high-rise building application: a comparative study, building simulation ( ) - . [ ] g.y. zhu, t.t. chow, c.k. lee. performance analysis of counter-flow regenerative heat and mass exchanger for indirect evaporative cooling based on data-driven model, energy and buildings ( ) - . [ ] yangda wan, chengqin ren, zhao wang, yang yang, lei yu. numerical study and performance correlation development on counter- flow indirect evaporative air coolers, international journal of heat and mass transfer ( ) – . geothermal and geopressure relations as tool for petroleum exploration: abstract; textural parameters of rocks from borehold measurements and their applications in determining depositional environments: abstract; discrimination among grain-size dist... association round table age of the rocks overlying both unconformities seems to indicate slow transgressive marine overlap in the two basins. miller, betty m., u.s. geol. survey, denver, colo. geothermal and geopressure relations as tool for petroleum exploration the uinta basin represents a timely model for the study of many interesting geologic and geochemical problems that are pertinent t o current exploration re- search investigations and to technical problems con- cerning petroleum production wliich face the petro- leum industry, particularly in light of the present energy crisis. the primary areas of investigation in this reported study on the uinta basin concern the com- plexities in the exploration of ultraparaffinic crudes from fresh- and brackish-water lacustrine sedimentary deposits. an investigative study of the subsurface tempera- ture and pressure distribution patterns within the po- tentially productive section of the wasatch formation (eocene) has produced highly favorable results as an exploration tool in predicting the recent successful ex- ploratory trends within the uinta basin. a direct rela- tion has been documented between the occurrence of productive hydrocarbons within the wasatch forma- tion and the simultaneous occurrences of high geotem- peratures, abnormally high pressures, and the presence of an organic-rich shale fades. these relations currently are being investigated as a potential tool for the ex- ploration of stratigraphic traps in tertiary basins. in addition, this study illustrates an application of computer techniques to geologic evaluations on a re- gional basis: rapid data-processing methods, data banks, computer-contoured maps, and statistical analysis of geologic data. pickett, g. r., and j. l. bedwell, colorado school mines, golden, colo., and j. c. carloss, consultant, bismarck, n.d. textural parameters of rocks from borehold measurements and their ap- plications in determining depositional environments no abstract available. poole, david m., marathon research, denver, colo. discrimination among grain-size distri- butions by canonical analysis as aid to environmental interpretation grain-size analyses of sediments and sedimentary rocks have been made for many purposes. during the last to is years, grain-size analyses have been made of sands and sandstones as a means of determining their depositional environments. most of the pub- lished work on discrimination of depositional environ- ments has been based on modern sands which contain little fine material the resxilts of this work generally cannot be applied t o sandstones because of the pre- sence of considerable amounts of diagenetic silt- and clay-sized material that often is present in sandstones. in the present study, sandstones were used rather than sands. a problem that always occurs when using grain- size analyses, regardless of whether they are of sands or sandstones, is that of comparing the size distribu- tions. canonical analysis is a statistical method of com- paring grain-size distributions. the primary aim of canonical analysis is to determine numerical character- istics that best separate size distributions or determine the characteristics they have in common. in using canonical analysis, a typical or model size distribution is selected against which all the size distributions are compared. if physical theory can be applied to the choice of a reference distribution or weight function, then the results may be interpreted more easily in a physical sense. two sets of numerical values are cal- culated for each size distribution. the discriminate functions show which variable or variables, size classes in this case, are important for discrimination; and the discriminate moments show how the size distributions are related so they may be sorted and classifled. a set of characteristic roots or eigenvalues also are calcu- lated. these eigenvalues, arranged in decreasing numer- ical order, show the proportion of variation among the distributions. generally, two to three characteristic roots, each having a set of discriminate functions and moments, account for most of the variation among the size distributions. canonical analysis techniques were applied to grain-size distributions of samples from known depo- sitional environments to see if discrimination could be achieved. outcrop samples from the gallup sandstone of the san juan basin, and brushy canyon formation of the delaware basin, and core samples from the " j " formation of the denver basin were used. even though the samples contained considerable amounts (greater than %) of silt- and clay-sized material, consistent grouping of similar types of size distributions were ob- tained. it was not possible to assign, from the grain- size data alone, groups of sandstone samples to specific depositional environments. the numbers generated by canonical analysis are not unique to a particular en- vironment. however, by using the canonical analysis techniques with grain-size data combined with a knowledge of sed- imentary structures of the same samples, a geologist can obtain more information about transportation mechanisms and depositional environments than could be obtained by the use of either approach separately. reynolds, mitchell w., u.s. geol. survey, denver, colo. early campanian (cretaceous) delta- front sedimentation, south flank of wind river basin, wyoming upper cretaceous rocks of the mesaverde forma- tion, exposed between hudson and muskrat creek on the south flank of the wind river basin, accumulated in an ascending accession of delta-front, tidal-flat, and delta-plain environments. rocks of the lower two en- vironments grade east and northeast into strata de- posited in an offshore marine environment, whereas rocks of the youngest environment grade east into de- posits of a delta-front platform. during early campan- ian time, the delta-front facies accumulated across a -km-wide belt near alkali butte, repeated fluctua- tions of strand position produced interbedded units of siltstone and sandstone in the facies, and intermittent development of low-relief bars permitted accumulation of estuarine or swamp sediments across subjacent deposits of the delta front. sandstone units of the delta-front facies show an upward gradation from siltstone and sandy siltstone microsoft word - p_ .doc sensors & transducers, vol. , issue , july , pp. - ssseeennnsssooorrrsss &&& tttrrraaannnsssddduuuccceeerrrsss © by ifsa publishing, s. l. http://www.sensorsportal.com specific energy consumption prediction method based on machine tool power measurement * guoyong zhao, qingzhi zhao, guangming zheng, jingtao zhai department of mechanical engineering, shandong university of technology, zibo , china * tel.: + - , fax: + - * e-mail: zgy @ .com received: may /accepted: june /published: july abstract: accurate prediction on energy consumption in machining is helpful to evaluate process energy characteristics and choose process methods for energy saving. specific energy consumption expresses the required energy consumption when cutting unit volume material. the back propagation (bp) neural network prediction method for specific energy consumption in machining is set up in the paper. the prediction method bases on machine tool power signal measurement by power analyzer and shunt sensors. in the developed bp neural network, the input layer neurons include spindle speed, feed rate, depth of cut and material removal rate; and the output layer neurons includes specific energy consumption in machining. the power signal measurement system is built up in the computer numerical control (cnc) milling machine tool, and the prediction method for specific energy consumption is tested with cutting data. the prediction results show that the introduced method is effective to predict specific energy consumption in machining. copyright © ifsa publishing, s. l. keywords: shunt sensor, power measurement, specific energy consumption, machining, bp neural network . introduction the global energy crisis and climate warming situation become more and more serious [ ]. recently, the low carbon revolution aimed to high energy efficiency and low emissions is carried out by some developed countries in the world, to cope with environment deterioration, climate change and energy crisis [ - ]. the developed countries and the international organization for standardization have launched a series of standards and laws related with energy-saving, low carbon technology. the manufacturing field is the state pillar industry. for one thing, it lays a solid foundation for improving the humankind spiritual civilization and material civilization. for another thing, it will consume a lot of resources and energy, and result in unnecessary losses and serious environmental pollution [ ]. consequently, the urgent task of the manufacturing industry is how to reduce the manufacturing resources, energy consumption and environmental pollution [ - ]. based on thermal dynamics, gutowski divided the energy consumption of the manufacturing process into two parts, the energy consumption to produce materials and the energy consumption to process products [ ]. and the former relates to the used material nature, material purity and manufacturing technology. the carbon emission in machining comes from energy consumption mainly, especially the http://www.sensorsportal.com/ sensors & transducers, vol. , issue , july , pp. - electric energy. the energy consumption in manufacturing fields account for about % of the total energy consumption in china, and more than % of emissions to cause environmental pollution come from manufacturing industry [ ]. in sum, how to reduce energy consumption and environment pollution caused by manufacturing industry is an urgent problem to deal with [ ]. the computer numerical control (cnc) machine tools are powerful, and have a lot of energy consumption parts, which include the spindle servo drive system, feed servo drive system, cooling and lubricating system, cnc device and plc part, lighting device, fan, chip system, cutter change device and other auxiliary system. the energy consumption includes cutting energy consumption, motors power loss, generalized energy storage, friction energy consumption, electrical components energy consumption, and auxiliary system energy consumption [ ]. the cnc machine tools components are divided into two categories by mori [ ]. one is the spindle motor and feed motor, whose energy consumption depends mainly on the cutting force, inertia force and friction force to move spindle box and table; the other is cooling lubrication peripheral equipment, whose energy consumption depends mainly on working time. shi analyzed the machine tool main motor power transmission characteristics and the mechanical transmission system characteristics, and established the dynamic power balance equations of the main drive system [ ]. hu et al. divided the main transmission system input power pin into the no-load power pu, cutting power pc, and additional load loss power pa further [ ]: acuin pppp  , ( ) where pu has connection with friction, damping and rotation rate; pc depends on the cutting parameters; and pa is the function of cutting power pc. balogun neglected the spindle system power losses due to friction, bearing vibration and heat when analyzing the main transmission system no- load power, and arrived at a conclusion that the no- load power pu is a piecewise linear function of the spindle motor rotation speed n [ ]. to sum up, energy consumption reduction is very important to protect environment and achieve sustainable manufacturing. so accurate prediction on energy consumption in machining is helpful to evaluate process energy characteristics and choose process methods for energy saving. but cnc machine tools have many function parts and the energy consumption is difficult to calculate precisely. the existing energy consumption prediction methods are analyzed, and the back propagation (bp) neural network prediction method for specific energy consumption in machining is built up in the paper. the prediction method bases on cnc machine tool power signal measurement by power analyzer and shunt sensors. the power signal measurement system is built up in a cnc milling machine tool, and the prediction method for specific energy consumption is testified with cutting data. . the existing machine tool energy consumption prediction methods in modern cnc machining process, the energy consumption of cutting movement is less than %, while the energy consumption of auxiliary systems occupies about %. the auxiliary systems include blanking, cutting fluid pump, start and brake, cnc system, cooling, lighting and so on [ ]. the existing machine tool energy consumption prediction methods include prediction methods based on machine tool function components and prediction methods based on empirical model mainly. . . the energy consumption prediction methods based on machine tool function components after establishing energy model of each cnc machine tool function component, braun predicted the energy consumption in machining according to process parameters, cutters, work piece materials [ ]. zhang divided the cnc machine tool energy consumption e into cutting energy consumption ec, air cutting energy consumption ea during non cutting stage, and tool change energy consumption et [ ]: tac eeee  , ( ) balogun divided the energy consumption e in machining into the standby energy consumption ebasic, the preparatory work energy consumption eready, and the energy consumption ecutting when cutting [ ]: cuttingreadybasic eeee  , ( ) liu established the cnc machine tool service process energy consumption prediction model according to three kinds of sub process, including start, no-load and processing [ ]. with the prediction model, the energy consumption in machining can be predicted according to process parameters. he et al. analyzed the energy characteristic of cnc machine tool function components, and set up the energy consumption prediction model [ ]: ))(( )( cos sefanservo coecooltooltool m i t t i t t c t t m ttpp ttptp dtpdtpdtpe fe fs ce cs me ms      , ( ) sensors & transducers, vol. , issue , july , pp. - the variables meaning are as follows: e is the total energy consumption when running the cnc codes; pm is the power enabling the operating state of the spindle transmission system; tms is the spindle system rotation starting time; tme is the spindle system rotation ending time; pc is the power of material removal; tcs is the cutting starting time; tce is the cutting ending time; pi is the ith axis feed servo motor power; tfs is the starting time of the ith axis servo motor; tfe is the ending time of the ith axis servo motor; ptool is the power of the tool change motor; ttool is the tool change time; pcool is the coolant pump motor power; tcoe-tcos is the coolant pump motor working time; pservo is the servos system power; pfan is the fan motors power; te-ts is the machine tool running time. . . the energy consumption prediction methods based on empirical model cnc machine tools have a lot of function components, and the energy consumption calculation in machining is very complex. the empirical models are advisable means to calculate energy consumption in machining [ ]. gutowski established machine tool efficiency model and energy consumption model, and considered that machine tools consume energy even at no-load operation state [ ]. the extra energy consumption in machining is directly proportional to the material process rate, and the power balance equation is as follows: vkpp  , ( ) the variables meaning are as follows: p is the total power in the cutting process in kw; p is the idle power in kw; k is constant in kj/cm ; v is the material processing rate in cm /s. kara developed the specific energy consumption prediction method for turning and milling process [ ]: mrr c sec c  , ( ) where: sec is the machine tool specific energy consumption in kj/cm ; c and c are constants; mrr: the material removal rate in cm /s. considering the cnc machine tool spindle drive system, no-load power consumption, standby power consumption and cutting energy consumption, li put forward specific energy consumption prediction model in dry cutting condition [ ]: mrr k mrr n kksec  , ( ) the variables meaning are as follows: k is the specific energy requirement in cutting operations; k is the specific coefficient of spindle motor; k is the constant coefficient of machine tool; n is the spindle speed; mrr is the material removal rate in cm /s. . the specific energy consumption prediction method based on bp neural network . . the process parameters and energy consumption in cnc turning and milling generally, cnc machine tool includes the spindle drive system, feed drive system, electric control system, lighting system, cooling system, lubricating system and chip system. the spindle drive system and feed drive system are defined as machine tool transmission system. the structure of cnc machining system is shown in fig. . fig. . the structure of cnc machining system. in cnc turning and milling, the cutting elements commonly include the spindle speed, feed rate and cutting depth. specifically, the spindle speed is used to specify the cnc machine tool spindle rotation rate in r/min; feed rate is the moving speed of the tool relative to work piece on the feed direction in mm/min; and cutting depth is the vertical distance between the machined surface and the unprocessed surface in mm. machining process is a dynamic system, which cuts work piece material with cutter, fixture, lubricating oil and coolant, and finally obtains the cnc machin e tool spindle drive system feed drive system electric control system auxiliary system cutter work piece and fixture sensors & transducers, vol. , issue , july , pp. - semi-finished or finished products. all of the process stages need to consume energy. each subsystem of mechanical processing is accompanied with the energy input, storage and release, loss and output. in general, the energy required for machining system is electric energy. . . the specific energy consumption prediction method based on bp neural network the specific energy consumption expresses the required energy consumption when cutting unit volume material. the advantage of specific energy consumption is that it can reflect the mapping relationship between the cutting energy consumption and the material removal rate. in other words, as long as the specific energy consumption is achieved, the machine tool energy consumption in machining can be predicted accurately. in cnc machining, the specific energy consumption depends on both the material removal rate and the specific cutting parameters. however, the existing specific energy consumption prediction models depend on material removal rate mainly, not considering specific cutting parameters such as the spindle speed, feed rate and cutting depth. so the bp neural network prediction method for specific energy consumption in machining is set up in the paper, which bases on cnc machine tool power signal measurement by power analyzer and shunt sensors. the machine tool power signal measurement system structure is shown in fig. . the voltage signal and current signal are measured from three phase power lines of cnc machine tool. the machine tool large current signals are converted into small voltage signals by shunt sensors to input power analyzer. the usb interface is used to achieve communication between power analyzer and personal computer (pc). the cnc machine tool power signals are measured and stored in pc, which provides data information for the specific energy consumption calculation. fig. . the machine tool power signal measurement system. bp network is an artificial neural network based on error back-propagation algorithm. as shown in fig. , the developed bp neural network for specific energy consumption prediction is a single hidden layer feedforward neural network, which includes input layer, hidden layer and output layer. the input layer consists of four neurons, such as the spindle speed, feed rate, depth of cut and material removal rate; while the output layer includes only one neuron, which is the specific energy consumption. in the bp neural network, each layer neurons connect fully only with the adjacent layers neurons, no connection between neurons in the same layer, and no feedback connections between the neurons in each layer. fig. . the bp neural network for specific energy consumption prediction. . the specific energy consumption prediction experiments in cnc milling . . the power signal measurement in milling process the process experiments are surface rough milling in the three-axis vertical milling cnc machine tool, with a hard alloy end mill cutter whose diameter is mm, with cooling liquid in the milling process, and the cutting width bd is mm, the work piece dimension is mm* mm* mm. in the machining process, the cnc milling machine tool power signals are measured with power analyzer and shunt sensors according to the hardware structure shown in fig. . the machine power signals are stored and analyzed in pc, and the pc software interface is shown in fig. . fig. . the machine tool power signals acquisition and processing. cnc machine tool three phase power lines voltage signal current signal (by shunt sensors) power analyzer pc (storage and analyze) usb … … spindle speed feed rate depth of cut material removal rate specific energy consumption sensors & transducers, vol. , issue , july , pp. - the process parameters and power signals are shown in table . the material removal rate mrr is calculated according to depth of cut ap, feed rate f, and cutting width bd. the specific energy consumption sec is computed according to machine tool power signals pin and material removal rate mrr. . . the specific energy consumption prediction with bp neural network as shown in fig. , the introduced bp network for specific energy consumption prediction is a single hidden layer feedforward neural network. the input layer neurons number n is , such as the spindle speed, feed rate, depth of cut and material removal rate. the output layer neuron number m is , the specific energy consumption. in general, the hidden layer neurons number n is determined according to empirical formula: nmn  , ( ) nn log  , ( ) )( . mnnn  , ( )  nn ( ) therefore, choose hidden layer with to neurons to train the bp network respectively. the bp network training curve with different hidden layer neurons number is shown in fig. , and the mean square error (mse) is shown in table . consequently, it can be seen from fig. and table , the bp neural network mean square error is least with hidden layer neurons. table . the process parameters and power signals. no. n(r/min) f(mm/min) ap(mm) pi n(kw) mrr(cm /min) sec(kj/cm ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - - - - epochs t ra in in g -b lu e g o a l- b la c k performance is . e- , goal is . (a) hidden layer with neurons - - - - epochs t ra in in g -b lu e g o a l- b la c k performance is . e- , goal is . (b) hidden layer with neurons sensors & transducers, vol. , issue , july , pp. - - - - - epochs t ra in in g -b lu e g o a l- b la c k performance is . e- , goal is . (c) hidden layer with neurons - - - - epochs t ra in in g -b lu e g o a l- b la c k performance is . e- , goal is . (d) hidden layer with neurons - - - - epochs t ra in in g -b lu e g o a l- b la c k performance is . e- , goal is . (e) hidden layer with neurons - - - - epochs t ra in in g -b lu e g o a l- b la c k performance is . e- , goal is . (f) hidden layer with neurons - - - - epochs t ra in in g -b lu e g o a l- b la c k performance is . e- , goal is . (g) hidden layer with neurons - - - - - - epochs t ra in in g -b lu e g o a l- b la c k performance is . e- , goal is . (h) hidden layer with neurons sensors & transducers, vol. , issue , july , pp. - - - - - epochs t ra in in g -b lu e g o a l- b la c k performance is . e- , goal is . (i) hidden layer with neurons - - - - epochs t ra in in g -b lu e g o a l- b la c k performance is . e- , goal is . (j) hidden layer with neurons fig. . the bp network training curve with different hidden layer neurons number. table . the bp network training results. hidden layer neurons number mse hidden layer neurons number mse . e- . e- . e- . e- . e- . e- . e- . e- . e- . e- consequently, the bp prediction network adopts - - structure. there are neurons in the input layer, neurons in the hidden layer, and neuron in the output layer respectively. the bp network is trained with the no. -no. group data in table . then the trained network is tested with the no. - no. group data in table . the predicted sec are . and . , and the prediction error are . % and . % relative to the actual sec of the no. -no. group data in table . in conclusion, the network prediction value is very close to the actual measurement value, and the developed bp network can predict specific energy consumption in milling process accurately after training. . conclusions the research on energy consumption in machining is helpful to analyze the machine tool energy characteristics, optimize process parameters and machine tool components for energy saving. specific energy consumption expresses the required energy consumption when cutting unit volume material. the bp neural network prediction method for specific energy consumption in machining is set up in the paper. the prediction method bases on machine tool power measurement by power analyzer and shunt sensors. the bp network adopts - - structure. there are neurons in the input layer, which express the spindle speed, feed rate, depth of cut and material removal rate. there is neuron in the output layer, which express the specific energy consumption in machining. the cnc milling machine tool power signal measurement system is built up, and the prediction method for specific energy consumption is tested with cutting data. the prediction results show that the introduced method is effective to predict machine tool specific energy consumption. acknowledgements the authors are grateful to the project of the national natural science foundation of china (no. ). references [ ]. joost r. duflou, john w. sutherland, david dornfeld, towards energy and resource efficient manufacturing: a processes and systems approach, cirp annals - manufacturing technology, , , , pp. - . 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[ ]. lin li, jihong yan, zhongwen xing, energy requirements evaluation of milling machines based on thermal equilibrium and empirical modeling, journal of cleaner production, , , pp. - . ___________________ copyright ©, international frequency sensor association (ifsa) publishing, s. l. all rights reserved. (http://www.sensorsportal.com) http://www.sensorsportal.com/html/digest/submission.htm http://www.sensorsportal.com/html/digest/submission.htm http://www.sensorsportal.com/html/digest/submission.htm no observed effect on brain vasculature of alzheimer’s disease-related mutations in the zebrafish presenilin gene barthelson et al. mol brain ( ) : https://doi.org/ . /s - - - m i c r o r e p o r t no observed effect on brain vasculature of alzheimer’s disease-related mutations in the zebrafish presenilin gene karissa barthelson * , morgan newman , cameron j. nowell and michael lardelli abstract previously, we found that brains of adult zebrafish heterozygous for alzheimer’s disease-related mutations in their pre- senilin gene (psen , orthologous to human psen ) show greater basal expression levels of hypoxia responsive genes relative to their wild type siblings under normoxia, suggesting hypoxic stress. in this study, we investigated whether this might be due to changes in brain vasculature. we generated and compared d reconstructions of gfp-labelled blood vessels of the zebrafish forebrain from heterozygous psen mutant zebrafish and their wild type siblings. we observed no statistically significant differences in vessel density, surface area, overall mean diameter, overall straight- ness, or total vessel length normalised to the volume of the telencephalon. our findings do not support that changes in vascular morphology are responsible for the increased basal expression of hypoxia responsive genes in psen heterozygous mutant brains. keywords: zebrafish, vasculature, confocal laser scanning microscopy, d reconstruction © the author(s) . open access this article is licensed under a creative commons attribution . international license, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the creative commons licence, and indicate if changes were made. the images or other third party material in this article are included in the article’s creative commons licence, unless indicated otherwise in a credit line to the material. if material is not included in the article’s creative commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. to view a copy of this licence, visit http://creat iveco mmons .org/licen ses/by/ . /. the creative commons public domain dedication waiver (http://creat iveco mmons .org/publi cdoma in/zero/ . /) applies to the data made available in this article, unless otherwise stated in a credit line to the data. introduction the dominant hypothesis of alzheimer’s disease (ad) pathogenesis is the amyloid cascade hypothesis (ach) [ ], which postulates the amyloid β peptide (aβ) as ini- tiating a pathological process resulting in neurodegen- eration and dementia (reviewed in ( )). an alternative to the ach is the vascular hypothesis [ ], asserting that age-related cerebral vascular abnormalities induce ad pathologies by limiting nutrient and oxygen delivery to produce hypoxic stress, a neural energy crisis and, con- sequently, neurodegeneration. significant evidence sup- ports the vascular hypothesis of ad (reviewed in [ ]). rare, inherited forms of ad are caused by dominant mutations in a small number of genes (early-onset famil- ial ad, eofad). most eofad cases are due to heterozy- gous mutations in the gene presenilin (psen ) that obey a “reading-frame preservation rule” [ ]. mutations allowing production of a transcript(s) with an altered coding sequence but, nevertheless, utilising the original stop codon cause eofad while mutant alleles coding only for truncated proteins do not. we previously gen- erated knock-in models in zebrafish with each of these types of mutant psen allele: k gfs, a frameshift muta- tion encoding a truncated protein similar to the human ps v isoform that is increased in sporadic, late onset ad [ ], and q _k del: an eofad-like, reading-frame-pre- serving deletion of two codons [ ]. we recently observed in normoxic adult zebrafish brains that heterozygosity for either of the above two muta- tions causes increased basal expression levels of hypoxia responsive genes (hrgs, genes with expression regulated by a master regulator of the transcriptional response to hypoxia: hypoxia-inducible factor (hif )). this implied that the heterozygous psen mutant fish brains were already under some form of hypoxic stress [ ], possibly due to changes in vasculature, as have been observed in open access *correspondence: karissa.barthelson@adelaide.edu.au alzheimer’s disease genetics laboratory, school of biological sciences, university of adelaide, north terrace, adelaide, sa , australia full list of author information is available at the end of the article http://orcid.org/ - - - http://creativecommons.org/licenses/by/ . / http://creativecommons.org/publicdomain/zero/ . / http://creativecommons.org/publicdomain/zero/ . / http://crossmark.crossref.org/dialog/?doi= . /s - - - &domain=pdf page of barthelson et al. mol brain ( ) : transgenic mice expressing human psen eofad muta- tion-bearing transgenes in neurons [ ]. therefore, we examined the effects on forebrain vasculature with age of heterozygosity for the k gfs and q _k del mutations of psen by exploiting the fli :gfp transgene that labels zebrafish endothelial cells [ ]. e d c b a page of barthelson et al. mol brain ( ) : methods single zebrafish heterozygous for either psen muta- tion were mated with single fish bearing the fli ::gfp [ ] transgene. gfp-fluorescent progeny were selected to form families of siblings either wild type or heterozy- gous for the psen mutant alleles (fig.  a). we used n = brains of each sibling genotype at  months (young adult) and  months (aged) of age for tissue clearing using the pact method [ ]. briefly, pact involves infusing and crosslinking the brain with an acrylamide-based hydro- gel. then, light scattering lipids are passively removed by incubating the brain with a detergent, allowing light to penetrate deep into the tissue [ , ]. we imaged the telencephalons (thought to be the region loosely equiva- lent of the prefrontal cortex in humans) using an olym- pus fv confocal microscope, and performed d image analysis using imaris v . (bitplane) (fig.  b). for a detailed description of methods, see additional file . results and conclusion no statistically significant differences between sibling genotypes at each age were observed for any of the meas- ured parameters (see fig.  ). this does not support that the increased basal levels of hrgs observed previously in our zebrafish psen mutants are due to vascular changes. however, subtle changes to vasculature due to psen gen- otype may be too small to detect using this method and further experimentation using a larger number of bio- logical replicates may increase statistical power to detect changes to these measured parameters. alternatively, other factors such as altered γ-secretase activity [ ] and/ or cellular ferrous iron levels [ ] may influence hif -⍺ activity to affect basal hrg expression. supplementary information the online version contains supplementary material available at https ://doi. org/ . /s - - - . additional file  . detailed description of sample preparation, imaging and d image analysis. additional file  . quantified values used to produce the graphs in fig. . abbreviations ach: amyloid cascade hypothesis; ad: alzheimer’s disease; aβ: amyloid beta; eofad: early-onset familial alzheimer’s disease; hif : hypoxia-inducible factor ; hif -⍺: hypoxia-inducible factor , alpha subunit; hrg: hypoxia response gene; psen : presenilin . acknowledgements confocal imaging data were generated at adelaide microscopy (the univer- sity of adelaide). authors’ contributions kb performed the experiments, mn and ml conceived the project, cn provided advice and access for d image analysis. all authors read and con- tributed to the final manuscript. funding grants gnt and gnt from the national health and medical research council of australia (nhmrc) funded this work, and supported mn and ml. kb is supported by an australian government research training pro- gram scholarship. ml is an academic employee of the university of adelaide. funding bodies did not play a role in the design of the study, data collection, analysis, interpretation or in writing the manuscript. availability of data and materials the quantified values used to produce the graphs in fig. can be found in additional file . raw microscopy images from the current study are available from the corresponding author upon reasonable request. ethics approval and consent to participate work with zebrafish was conducted under the auspices of the university of adelaide animal ethics committee (permit numbers: s- - and s- - ) and institutional biosafety committee (permit number ). (see figure on previous page.) fig. no statistically significant changes to brain vascular network parameters due to heterozygosity for the q _k del or k gfs mutations of psen . a experimental design flow diagram. genome-edited psen heterozygous mutant fish were pair-mated with transgenic zebrafish expressing green fluorescent protein (gfp) under the control of the fli promotor (fli :gfp transgene). gfp-fluorescent larvae were selected to give a family of transgenic siblings either wild type or heterozygous for a psen mutation. analysis of the brain vascular network was performed at and months of age. b d image analysis pipeline. the telencephalon was manually segmented from the optic tectum using contour lines to generate a masked surface channel containing only gfp signals from the telencephalon. then, an additional surface was generated over the vessels to remove background fluorescence. a masked surface channel was generated from this surface as input for the filament trace algorithm. c measured values from the surface and filament trace algorithms for the month old zebrafish and d the month old female zebrafish for (left to right) the volume of the telencephalon, the density of fli :gfp positive vessels per telencephalon, the surface area of vessels normalised to the volume of the telencephalon, the overall mean diameter of vessels, the overall straightness of the vessels, and the total length of the vessels normalised to the volume of the telencephalon. data are presented as the mean ± standard deviation. colours of the bars represent the two families of fish used in this analysis. p-values were determined by student’s t-test assuming unequal variance. e representative images of a µm section of the right hemisphere of the telencephalon from fish of each age and genotype. scale bars indicate µm. vessels appeared morphologically similar in each age and genotype https://doi.org/ . /s - - - https://doi.org/ . /s - - - page of barthelson et al. mol brain ( ) : • fast, convenient online submission • thorough peer review by experienced researchers in your field • rapid publication on acceptance • support for research data, including large and complex data types • gold open access which fosters wider collaboration and increased citations maximum visibility for your research: over m website views per year • at bmc, research is always in progress. learn more biomedcentral.com/submissions ready to submit your researchready to submit your research ? choose bmc and benefit from: ? choose bmc and benefit from: consent for publication not applicable. competing interests the authors declare that they have no competing interests. author details alzheimer’s disease genetics laboratory, school of biological sciences, university of adelaide, north terrace, adelaide, sa , australia. drug discovery biology, monash institute of pharmaceutical sciences, monash university, parkville, vic , australia. received: november accepted: january references . hardy ja, higgins ga. alzheimer’s disease: the amyloid cascade hypoth- esis. science. ; ( ): – . . morris gp, clark ia, vissel b. questions concerning the role of amyloid-β in the definition, aetiology and diagnosis of alzheimer’s disease. acta neuropathol. ; ( ): – . . de la torre jc, mussivan t. can disturbed brain microcirculation cause alzheimer’s disease? neurol res. ; ( ): – . . rius-pérez s, tormos am, pérez s, taléns-visconti r. vascular pathology: cause or effect in alzheimer disease? neurología (english edition). . https ://doi.org/ . /j.nrlen g. . . . . jayne t, newman m, verdile g, sutherland g, munch g, musgrave i, et al. evidence for and against a pathogenic role of reduced gamma-secretase activity in familial alzheimer’s disease. jad. . https ://doi.org/ . / jad- . . hin n, newman m, kaslin j, douek am, lumsden a, nik shm, et al. accel- erated brain aging towards transcriptional inversion in a zebrafish model of the k fs mutation of human psen . plos one. ; ( ):e . . newman m, hin n, pederson s, lardelli m. brain transcriptome analysis of a familial alzheimer’s disease-like mutation in the zebrafish presenilin gene implies effects on energy production. mol brain. . https ://doi. org/ . /s - - -y. . newman m, nik hm, sutherland gt, hin n, kim ws, halliday gm, et al. accelerated loss of hypoxia response in zebrafish with familial alzheimer’s disease-like mutation of presenilin . hum mol genet. ; ( ): – . . gama sosa ma, gasperi rd, rocher ab, wang ac, janssen wg, flores t, et al. age-related vascular pathology in transgenic mice expressing pre- senilin -associated familial alzheimer’s disease mutations. am j pathol. ; ( ): – . . lawson nd, weinstein bm. in vivo imaging of embryonic vascular development using transgenic zebrafish. developmental biology. ; ( ): – . . yang b, treweek jennifer b, kulkarni rajan p, deverman benjamin e, chen c-k, lubeck e, et al. single-cell phenotyping within transparent intact tissue through whole-body clearing. cell. ; ( ): – . . chung k, wallace j, kim s-y, kalyanasundaram s, andalman as, davidson tj, et al. structural and molecular interrogation of intact biological sys- tems. nature. ; : . . le moan n, houslay dm, christian f, houslay md, akassoglou k. oxygen- dependent cleavage of the p neurotrophin receptor triggers stabiliza- tion of hif- α. mol cell. ; ( ): – . . yambire kf, rostosky c, watanabe t, pacheu-grau d, torres-odio s, sanchez-guerrero a, et al. impaired lysosomal acidification triggers iron deficiency and inflammation in vivo. elife. . https ://doi.org/ . / elife . . publisher’s note springer nature remains neutral with regard to jurisdictional claims in pub- lished maps and institutional affiliations. https://doi.org/ . /j.nrleng. . . https://doi.org/ . /jad- https://doi.org/ . /jad- https://doi.org/ . /s - - -y https://doi.org/ . /s - - -y https://doi.org/ . /elife. https://doi.org/ . /elife. 	no observed effect on brain vasculature of alzheimer’s disease-related mutations in the zebrafish presenilin gene 	abstract 	introduction 	methods 	results and conclusion 	acknowledgements 	references science american association for the advancement of science science serves its readers as a forum for the presentation and discussion of important issues related to the advance- ment of science, including the presentation of minority or con- flicting points of view, rather than by publishing only material on which a consensus has been reached. accordingly, all ar- ticles published in science-including editorials, news and comment, and book reviews-are signed and reflect the indi- vidual views of the authors and not official points of view adopted by the aaas or the institutions with which the au- thors are affiliated. pubiisher: richard s. nicholson editor: daniel e. koshland, jr. news editor: ellis rubinstein managing editor: patricia a. morgan deputy editors: philip h. abelson (engineering and applied sciences); john . brauman (physical sciences) editorial staff assistant managing editor: monica m. bradford senior editor: eleanore butz asaociate editors: keith w. brocklehurst, martha coleman, r. brooks hanson, barbara jasny, katrina l. kelner, edith meyers, linda j. miller, phillip d. szuromi, david f. voss letters editor: christine gilbert book reviews: katherine livingston, editor; susan milius contributing editor: lawrence . grossman chief production editor: ellen e. murphy editing department: lois schmitt, head; mary mcdaniel, patricia l. moe, barbara p. ordway copy desk: joi s. granger, jane hurd, marybeth shartle, beverly shields production manager: james landry assistant production manager: kathleen c. fishback art director: yolanda m. rook graphics and production: holly bishop, julie cherry, cath- erine s. siskos systems analyst: william carter news staff cormspondent-at-large: barbara j. culliton dsputy news editors: roger lewin, colin norman news and commentresearch news: mark h. crawford, constance holden, richard a. kerr, eliot marshall, jean l. marx, joseph palca, robert pool, leslie roberts, marjorie sun, m. mitchell waldrop european correspondent: jeremy cherfas west coast correspondent: marcia barinaga business staff circulation director: john g. colson fumilment manager: ann ragland business staff manaer: deborah rivera-wienhold advertising representatives director: earl j. scherago trafc manager: donna rivera traffic manager (recruitment): gwen canter advertising sales manager: richard l. charles marketing manager: herbert l. burklund employment saies manager: edward c. keller salis: new york, ny ; 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( - - ); san jose, ca : bob brindley, s. th st. ( - - ); dorset, vt : fred w. dieffenbach, kent hill rd.( - - ); damascus, md : rick sommer, kings valley dr. ( - - ); u.k., europe: nick jones, + ( ) ; telex ; fax ( ) . information for contributors appears on page xl of the june issue. editorial correspondence, including requests for permission to reprint and reprint orders, should be sent to h street, nw, washington, dc . tele- phone: - - . advertising correspondence should be sent to tenth floor, broadway, new york, ny . telephone - - or wu telex scherago, or fax - - . september september volume number hydrocarbon energy revisited m any energy experts now project a continuation of relatively low prices for oil for much of the next decade. this would lead to a large increase in u.s. importation of oil and help opec eventually to resume ability to dictate high prices. the facts and trends on which the current estimates are based seem solid. from to non-u.s., non-opec free world production increased fivefold. this, together with conservation and substitution induced by high prices for oil, led to a drop in sales by opec from to of almost %. to avoid a further loss of market share the price was drastically reduced by saudi arabia and others. the current level of prices has slowed exploration and drilling by non-opec countries, but with excess production capacity already in place, there is little likelihood of a substantial rise in world oil prices in the next several years, short of a major mideast conflagration. the effects of continuing low world oil prices on the complex u.s. energy system would be many and profound. some of them are already apparent. efforts in conservation, improved energy efficiency, and substitution of other fuels for oil have diminished. exploration and drilling for hydrocarbons has dropped; production of petroleum has decreased; consumption of petroleum is increasing; imports of oil and its products have risen. additional effects such as tightness in supplies of natural gas and price increases for that fuel will become apparent later. a possible future development is sharply expanded dependence on hydrocarbons for generation of electric power. before the early s the contiguous continental united states had already become a mature petroleum province; costs offinding oil in it exceeded those of many countries. high prices for oil in the early s led to extensive drilling here, but the current rate is only about a fifth of the peak. unless substantial reserves are added, production capability diminishes with time. in production ofcrude oil plus condensate totaled . million barrels per day (mbd). in it was . mbd, and in it will be . mbd. experts predict that in the year it will be mbd. consumption of petroleum increased an average of . % per year between and ( mbd of products in ). experts predict that demand will continue to increase, but at the rate of only . to . % per year. this slow rate prediction could be an underestimate. in , while high prices still prevailed, net imports of oil and its products were . mbd. in they were . mbd. during they will be about . mbd. a recently released conoco report, "world energy outlook through ," projects imports of mbd in the year . the estimate is based on the assumption that use of oil will increase at the slow rate. for many purposes oil and natural gas are interchangeable as fuels. this is particularly true in industrial applications and when they are used in power generation. many of the large consumers can easily switch back and forth. when oil is cheap, the price for natural gas is depressed and drilling for gas is curtailed. already, producible reserves of natural gas have diminished. when cheap natural gas is no longer available, it will be supplanted by oil. demand for hydrocarbons by the electrical utilities could lead to substantially enhanced importation of oil during the next decade. in the past, most of the base load generating plants have been fueled by coal; nuclear energy now contributes about % of electric power. however, only a few nuclear and coal plants are under construction. if demand for electricity continues to grow at a rate approaching that experienced in and , the united states is headed for large shortages of base load capacity. construction of coal and nuclear plants is costly and requires many years. in contrast, combined cycle plants fueled by natural gas or oil can be put into operation quickly and at low capital cost. apparently many of the utilities are planning to pursue this course. but it is a course that would increase imports of oil further. substantial increases in importation of oil by the united states, southeast asia, and the less developed countries could restore control of the market to opec by the year or before. unless there are economic incentives for improving energy efficiency, conservation, and substitution and for increasing domestic supplies, the united states will become increasingly vulnerable to a great, multicomponent energy crisis.-philip h. abelson editorial i o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ hydrocarbon energy revisited philip h. abelson doi: . /science. . . 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second, what improvements can be made for the current programs in order to better suit them with practical requirements? with the above two questions, an overview of the programs for green building design is presented in this paper. due to the large number of programs falling into the scope of this study, a classification system was established to group the available programs into several categories for discussion. a few representative programs for each category were selected and briefly discussed with emphasis on their pros and cons. on the basis of the programs’ analysis, a model is proposed at the end of this paper to hopefully address the drawbacks of most programs for green building design. keywords green building, overview, software, life-cycle assessment, environmental impact the bulletin of the institue for palestine studies a bi-weekly, arabic-language publication on zionist and israeli affairs, the bulletin bases its material on hebrew sources and the israeli news media. some of the subjects that were treated in : land procurement in the occupied territories and jewish settlement. the complete text of the conference of israeli ex- chiefs-of-staff published in maariv on february . the third economic convention of jewish millionnaires in jerusalem. the complete text of waldheim's report of april to the security council on jarring's mission. israel and the world energy crisis. the population in israel: analysis and prediction up to . as well as: israeli party conferences, the bologna conference (italy), palestinian resistance activi- ties and israeli reprisals, brandt's visit to israel, immigration, israel's foreign relations, the development of conditions in the occupied territories, etc. annual subscription: us $ . (individuals) us $ . (institutions) available directly from: the institute for palestine studies p.o. box , beirut, lebanon terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core " a revolution which does not aim at changing me by changing relations between people does not interest me; what is more, i doubt whether a revolution which does not affect me enough to transform me is really a revolution at all. the palestinian revolution has established new kinds of relations which have changed me, and in this sense the palestinian revolution is my revolution. " jean genet jean genet's article the palestinians appears in the autumn issue of the journal of palestine studies one copy $ . , one year $ . (students $ . ) prepaid. j.p.s. distribution, box , r.d. i, oxford, pa. , usa. m terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/ . /s downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core https://www.cambridge.org/core/terms https://doi.org/ . /s https://www.cambridge.org/core the comparative life cycle assessment of power generation from lignocellulosic biomass sustainability , , - ; doi: . /su sustainability issn - www.mdpi.com/journal/sustainability article the comparative life cycle assessment of power generation from lignocellulosic biomass xinhua shen ,†, raghava r. kommalapati , ,* and ziaul huque , nsf crest center for energy & environmental sustainability, prairie view a&m university, prairie view, tx , usa; e-mails: xinhua.shen@uni.edu (x.s.); zihuque@pvamu.edu (z.h.) department of civil and environmental engineering, prairie view a&m university, prairie view, tx , usa department of mechanical engineering, prairie view a&m university, prairie view, tx , usa † current address: department of earth sciences, university of northern iowa, cedar falls, ia , usa. * author to whom correspondence should be addressed; e-mail: rrkommalapati@pvamu.edu; tel: + - - - ; fax: + - - - . academic editor: andrew kusiak received: august / accepted: september / published: september abstract: in order to solve the energy crisis and reduce emissions of greenhouse gases (ghg), renewable energy resources are exploited for power generation. because lignocellulosic biomass resources are abundant and renewable, various technologies are applied to using lignocellulosic biomass to derive biofuel and electricity. this paper focuses on power generation from lignocellulosic biomass and comparison of the effects of different feedstocks, transportation, and power generation technologies evaluated through life cycle assessment (lca). the inputs and boundaries of lca vary with different feedstocks, such as forestry wood, agricultural residues, and fast-growing grass. for agricultural residues and fast-growing grass, the transportation cost from field to power plant is more critical. three technologies for power generation are analyzed both with and without pelletization of lignocellulosic biomass. the ghg emissions also vary with different feedstocks and depend on burning technologies at different plant scales. the daily criteria pollutant emissions of power generation from different lignocellulosic biomass were evaluated with a life cycle assessment model of greet.net . it is concluded that bio-power generation is critical with the urgency of greenhouse effects. open access sustainability , keywords: life cycle assessment; lignocellulosic biomass; power generation; ghg emissions . introduction the united nations has recently reported that global warming is mainly due to progressive consumption of fossil resources on the earth [ ]. the current energy consumption structure mostly depends on coal, oil, and natural gas for power generation and chemical productions in most countries and results in substantial emissions of greenhouse gases (ghgs) [ , ]. ghgs, such as co , ch , o , and n o, play an important role in global climate change. the increase of ghg level changes the climate and further influences natural ecosystems, water resource distribution and agricultural production. in order to reduce the climate change, some efforts have been made to reduce the emission of ghgs. the united nations proposed some policies and actions associated with energy consumption to limit net ghg emissions. the kyoto protocol agreed by numerous countries was another milestone. some countries in america, europe, and asia started to widely consider different renewable energies as potential long-term sources of energy supply in the s or even earlier. it has been reported that, starting from , renewable energy has accounted for eight percent of the energy supply in the united states. thus, renewable biomass plays a significant role in the energy supply in the world, especially in the united states. lignocellulosic biomass is widely distributed in the different forms, e.g., forestry, energy crops, and agricultural residues. various technologies [ ] have been developed to use lignocellulosic biomass in gasification, biofuel derivation, and electricity power generation. the gasification of wood or forestry residue was widely used when oil was deficient in world war ii, but the technology was not efficient enough. currently, many research resources are being put into biofuel generation, including bioethanol and biodiesel from various types of lignocellulosic biomass. the first generation of biofuel generation technologies have been successfully applied to corn, soybeans, sugarcane, and beets to extract bioethanol and biodiesel, however, this partially contributes to the increase of food price in the world. starting from the s, more efforts have been shifted to non-food lignocellulosic biomass, mainly from crop residues, switch grass, fast-growing wood, forest residues, etc. the second generation technologies for biofuel currently encounter many challenges at the experimental step, especially for bioethanol from the land-planted biomass. however, burning biomass to generate electricity and heat is relatively easy and has been widely used in some european countries since the s and started from the pioneered plants in america and asia in the st century. biomaterial constitutes the world’s largest renewable resource for power generation. lignocellulosic biomass resources available for power generation mainly include agricultural crop residues (such as wheat straw, corn stover, rice straw, and other cultured plant stems), wood and its wastes from forestry and industry (such as bough, bark, and sawdust), dedicated short-rotation energy coppice (such as eucalyptus, poplar, and willow), and grass (such as switch grass and other natural grasses). the renewable biomass generally includes three main components: cellulose, hemicellulose, and lignin; and cellulose and hemicellulose make up approximately % of the entire biomass [ , ]. sustainability , agricultural crop residues include %– % hemicelluloses, %– % celluloses, %– % lignin, and %– % ash; the compounds of grass, such as switch grass, are similar to agricultural crop residues; and wood residues including hard wood and soft wood are divided into %– % hemicelluloses and %– % cellulose, %– % lignin, and a little amount of ash. this article focuses on the investigation of power generation from lignocellulosic biomass with different candidates, as well as the efficiency improvement for electricity and heat generation evaluated from life cycle assessment [ – ]. life cycle assessment, also called life cycle analysis (lca), evaluates the environmental burdens by identifying resource inputs, energy consumptions, and emissions to various environmental compartments resulting from the particular life cycle of a product. it commonly comprises of four steps, goal and boundary definition, inventory analysis, impact assessment, and impact interpretation. here, different models of lca are evaluated to clarify the environmental effects of different types of lignocellulosic biomass according to environmental impacts during the whole process of power generation through discussion of the energy, supply consumption and ghg emissions. the whole process starts from the biomass plantation and ends at waste releases in power plants. . feedstock of lignocellulosic biomass and preparations . . feedstocks from forestry wood and the cultivation thirty percent of lignocellulosic biomass produced every year in the united states is forest woody feedstock and it is about million tons [ ]. forest woody materials are generally classified into softwoods and hardwoods. most softwoods grow faster and possess lower wood densities which generally mean lower energy densities; and most hardwoods grow slower and have higher energy densities. softwoods are from gymnosperm trees, mostly evergreen species, e.g., pine, spruce, cypress, fir, hemlock, and redwood. hardwoods are deciduous trees, e.g., poplar, willow, oak, cottonwood, and aspen. wood residues, such as sawdust and barks from sawmills, wood chips, and branches from dead trees can also be used as lignocellulosic biomass feedstocks. compared to agricultural biomass, which has to be collected at its ripe time, woody materials can be collected, transported and stored flexibly with time. similar to the forestry wood, fast-growing trees, such as willow, poplar, black locust, eucalyptus, chestnut, etc., can also be used as biomass for power generation [ – ]. fast-growing wood has been used to produce fuelwood, furniture materials, fiber for paper and cellulose industries, and also for bioenergy [ ]. fast-growing wood has many advantages, such as high yield in short time cycle, low cost of plantation and management, and possible opportunities for planting on non-agricultural lands. these fast growing trees have been planted in many countries, e.g., china, india, the united states, and some european countries. for example, poplar, black locust, eucalyptus, and willow were planted in different areas, depending on different climate and land options in spain [ , ]. the plantation densities, the cultivation time periods, and the harvest of different fast wood crops are listed in table . it obviously shows that the harvest mainly varies with different crop types and plantation densities. sustainability , table . summary of the plantation densities, the cultivation time periods and the harvest of different fast wood crops in spain [ , ]. crop plantation density cultivation period yield/year eucalyptus plants ha− years . t ha− ·year− poplar , plants ha− years . t ha− ·year− black locust plants ha− years t ha− ·year− willow , plants ha− years t ha− ·year− . . feedstocks from agricultural crop residues and the cultivation agricultural crop residues are among the cheapest and most widespread lignocellulosic biomass resources. they are mostly from agricultural wastes, such as wheat straws, corn stover, rice straws, and husk, as well as non-food parts of other planted crops. similar to the availability of forestry wood feedstocks, approximately – million tons of agricultural crop residues can be harvested per year in the united states [ ]. they are mainly the residues from corn stover, rice, and wheat straws, and can be considered as the bioenergy feedstocks with the most potential in agricultural areas. agricultural crop residues have a lower density than forestry wood and fast-growing wood, and are relatively expensive in collection and transportation. however, alternative use of agricultural residues can help us to avoid reliance on forestry wood and reduce deforestation. another important aspect is that agricultural residues are the additional product of crop grain and can generally be harvested every year, so agricultural residues can be considered consistently available for bioethanol and power generation [ , ]. in contrast to forestry wood, the costs of the agricultural crop cultivation are critical. with regard to winter wheat cultivation in two european countries [ ] as an example compared with corn plantation, table shows that the inputs and outputs vary according to differences in the climate and field conditions in the two countries. in the table, the yield straw is calculated on the ratio of grain and straw as : . . table . main inputs and outputs of winter wheat cultivation compared with corn in germany and poland. parameter unit winter wheat reference source corn [ ] germany poland yield grain kg·ha− [ ] yield straw kg·ha− diesel kg·ha− [ ] seeds kg·ha− [ ] n-fertilizer kg·ha− [ ] p-fertilizer kg·ha− [ ] k-fertilizer kg·ha− [ ] herbicides kg·ha− . . [ ] insecticides kg·ha− . n.a. [ ] sustainability , . . perennial fast-growing grass and the cultivation switch grass is perennial warm season bunchgrass that is native to the north american hemisphere, mainly in canada and the united states [ , ]. switch grass is not only a fast-growing grass, but also has some advantages, such as low cost compared to agricultural crops, wide distribution and abundance in the united states, and low maintenance, requiring little to no fertilization. although typically shorter than big bluestem grass or indian grass, switch grass can grow up to . meters high. switch grass has another more attractive advantage of resistance to conditions of drought and high temperature because it uses c carbon fixation like corn. because switch grass is perennial, self-seeding and has lifetime around years or even longer, it does not need planting and reseeding after annual harvesting. however, in order to guarantee high yield every year, the necessary input and maintenance of the fast-growing grass are suggestive. miscanthus giganteus is another perennial fast-growing grass that is a great candidate for power generation and biofuel production. it is native to asia and has been planted in europe for combustible energy use [ ]. in table , the inputs for cultivation and outputs from switch grass and miscanthus [ ] are listed. table . the input of cultivation and output of switch grass and miscanthus [ ]. parameter units switch grass miscanthus planting year n-fertilization kg·ha− - - p-fertilization kg·ha− k-fertilization kg ha− seeds kg·ha− productive years n-fertilization kg·ha− p-fertilization kg·ha− k-fertilization kg·ha− yield mg·ha− . the role of transportation and pelletization in the lca in contrast to renewable resources like wind, solar, and hydropower, the biomass feedstocks for electricity generation must be produced, collected, transported, and stored before their use in a power plant. the cost of biomass materials used in biomass power generation is critically dependent upon the availability of a secure long-term supply of biomass feedstock at a competitive price. the current worldwide cost of biomass feedstock can represent % to % of the total cost of electricity produced from biomass [ ]. considering the convenience, the lowest cost feedstock is agricultural residue, such as local wheat straw or rice straw, corn stover, and other agricultural residues, when they are collected at harvest. for forestry wood or residue, the collection and transportation costs are predominant. comparing to coal and petroleum, the lower energy density of biomass feedstocks limits the transportation distance from a power plant, and farther transportation adds more feedstock costs in a power plant. table lists the typical costs of corn stover transportation, which are related to different equipment reported in the united states, and the data with farmer-owned equipment is calculated based on ha ( acres) [ ]. sustainability , bales of grass or agricultural residues and wood chips are convenient in the harvesting process, however, their low bulk and energy densities are the drawbacks for transportation [ , ]. compared to the conventional forms of bales and chips from agricultural and forest biomass resources for power generation, pelletization of these resources is one major technology to save on transportation costs and to improve the efficiency of fuel conversion in the final process. because of high density and low water content of pellets, pelletization reduces transportation cost and improves the conversion efficiency in power plants [ ]. pelletization also minimizes dust formation and helps the feed of free flow of biomass fuels because of the regular size of pellets. table . transportation cost per ton with custom/owned equipment [ ]. transportation distance cost with custom equipment cost with farmer-owned equipment km $ . $ . km $ . $ . km $ . $ . km $ . $ . km $ . $ . km $ . $ . km $ . $ . km $ . $ . km $ . $ . km $ . $ . . the role of power generation methods in the lca there are three primary technologies applied for the biomass combustion in electricity factories, direct or dedicated burning and combined heat and power (chp), co-firing with coal and gasification. the cost and efficiency of biomass power generation vary significantly by those three technologies. equipment costs for each technology used in the power plants are also different, depending on the region, the nature of different feedstocks, feeding forms with bales, chips or pellets, and the scale of the power plants. figures and show the inputs, different feedstocks, transportation, and different burning technologies in the pathways of power generation with/without pelletization. figure . the power generation pathway from lignocellulosic biomass without pelletization. sustainability , through combustion in dedicated power and chp plants biomass can be used to produce electricity and chp via a steam turbine. direct combustion is the oldest and simplest, but most inefficient burning technology. the typical efficiency of direct combustion with biomass was . %– % in the s [ ], and it has been improved to %– %, depending on the scale of biomass power plants, different feedstocks and feeding forms, e.g., bales, chips and pellets [ ]. in chp plants, the system of heat generation is parallel with electricity production, producing steam, hot water, or chilled water, optimally designed for the customer’s needs and requirements of heating factories, green houses, etc. the total plant efficiency of chp can reach %– % [ ]. the typical size of chp plants is usually ten times smaller (from to mw) than coal-based plants, depending on the availability of local feedstocks. because of low sulfur content in lignocellulosic biomass, emission of pollutants from chp plants can be effectively controlled compared to the coal-based plants. figure . the power generation pathway from lignocellulosic biomass with pelletization. with moderate additional investment, lignocellulosic biomass co-firing in modern, large-scale coal-based power plants can be more efficient and cost-effective. the co-firing technology has been applied in north europe, the united states, australia, and some asian countries, using different feedstocks, such as forestry wood or residues, agricultural residues, and fast-growing crops [ , – ]. the combustion efficiency of %– % in large-scale plants is higher than that of biomass direct combustion plants, although it is lower than that in pure coal-based plants [ ]. generally, co-firing technology decreases the emissions compared to direct combustion, however, it depends on many factors [ ], such as different biomass resources and coal characteristics, the coal utility boiler configuration and scale, etc. in the gasification process, biomass conversion into syngas can be either from slow anaerobic fermentation or fast thermo-chemical processes, e.g., pyrolysis at elevated temperatures in the absence of oxygen and gasifying with common agents, such as air, oxygen, and/or steam [ , ]. slow anaerobic fermentation converts only %– % feedstock into biogas, but produces soil conditioners as a byproduct. fast thermo-chemical processes produce much more biogas and even leave only %– % of ash through pyrolysis. currently, the biomass integrated gasification combined cycle is the most common approach for power generation from lignocellulosic biomass [ ]. gasification has higher efficiencies; however, it requires a significant investment and operations at elevated sustainability , temperatures with extra energy consumption [ , ]. compared to the previous two technologies, the emissions of burning biogas obtained from lignocellulosic biomass through gasification is the lowest. . ghg emission caused by power generation from lignocellulosic biomass most lignocellulosic biomass is composed of about % carbon, % oxygen, and % hydrogen by weight, as well as very small amounts of other elements. burning biomass results in various emissions and most emissions are co , h o with . % nox and some co and ch using poorly-maintained equipment. in addition, the total emissions include some pollutants of . % sulphur, . % chlorine, and trace quantities of inorganic minerals, such as calcium, potassium, silicon, phosphorus, and sodium [ ]. the compositions of emissions depend on many factors, including the growing environment of plants, the plant species, any contaminants in the soil, water, or air, etc. in most cases, power generation from lignocellulosic biomass produces low net carbon emissions, mostly in the form of co , and % or less of total emissions of other ghgs, such as ch and nox [ , ]. burning biomass also avoids anaerobic decomposition that results in ch emissions, which are known to have times the greenhouse effects of co . generally power production from biomass is considered carbon neutral, with burning emissions balanced by the carbon capture of the next crop [ , ]. in some instances, with non-invasive farming methods, some researchers even claimed carbon negativity which means that less carbon is emitted than is removed from the atmosphere [ , ]. the ghg emissions from the combustions of biomass vary with biomass feedstocks, different forms, and power generation methods. table lists emission factors (emissions in kilogram per ton of biomass) for the combustion of biomass in different forms when only co emissions are considered carbon neutral [ , , ] and other emissions are accounted for. ghg emissions of burning lignocellulosic biomass are generally, but not always, lower than the combustions of fossil fuel and coal. for example, using short rotation coppice chips or fast-growing trees in power plants can reduce % to % emissions than a combined cycle gas turbine power station, however, the emissions from using wheat straw, rice straw, or corn stover, reduces % emission savings. transporting lignocellulosic biomass over long distances and excessive use of nitrogen fertilizers for short rotation coppice or switch grass further reduce the emissions savings by %– % [ ]. table . emission factors for of biomass combustion in different forms (units: kg/t) [ , , ]. emissions forestry wood pellet forestry wood chip agricultural residue pellet agricultural residue bale co ch . . . . n o . . . . co . . . . voc . . . . nox . . . . so . . . . the daily criteria pollutant emissions of power generation from different lignocellulosic biomass, such as forestry residue, miscanthus, willow, poplar, and switchgrass were evaluated through life cycle sustainability , assessment by using greet.net (the greenhouse gases, regulated emissions, and energy use in transportation model, version) [ ]. the capacity of the different power plants is mw, which falls in a small plant scale. the mode of well-to-pump was used in the simulation. table shows the characteristics of farming inputs and different emissions of electricity generation with different lignocellulosic feedstocks in the usa in . the unit kg/t refers to the usage of fertilizers or herbicides in kg for a ton output of dry biomass in the pathway. here, the same transportation distance of miles is used for all the biomass types. we can see that the pollutant emissions of voc, co, nox, pm and pm . , and the ghg emissions are similar for all the feedstocks. the sox emissions vary with different feedstocks: the emission from burning forestry residue is the greatest, and those from poplar are the smallest. the n o emissions also vary with different feedstocks and the emissions from switchgrass are the greatest. the daily net emissions of the ghgs (co -equivalent) for all the different feedstocks are much lower than those at on-site power plants. the lowest ghg emissions are achieved with the willow feedstock. table . the characteristics of farming inputs and daily emissions of electricity generation with different lignocellulosic feedstocks. farming unit forest residue miscanthus willow poplar switchgrass n-fertilizer kg/t n/a . . . . p-fertilizer kg/t n/a . n/a . . k-fertilizer kg/t n/a . n/a . . herbicides kg/t n/a . . . . calcium carbonate kg/t n/a n/a n/a . n/a voc kg . . . . . co kg . . . . . nox kg . . . . . pm kg . . . . . pm . kg . . . . . sox g . . . . . ch kg . . . . . n o kg . . . . . co kg , . , . , . , . , . ghgs kg . . . . . . uncertainty analysis of electricity generation from lignocellulosic biomass the emission analysis described herein is limited to parameters for which data were readily available in greet.net . within the lca, differences in agricultural chemical usage and transportation distances usually vary between scenarios. this analysis does not consider the environmental impacts driven by land-use change, either direct or indirect, or impacts resulting from establishing new infrastructure for power plants. however, increasing demand for power generation from lignocellulosic biomass may significantly change land use patterns and stimulate infrastructure construction. the emission factors of each pathway should be determined with the characteristics of different feedstocks, the details of different technologies of power generations and the power plant scales. for examples for chp power generation, the emission factors rely on the details of the boilers sustainability , installed and the plant scales. the achievement of power-generation increases from biomass depends on biomass power plant capacity and regional feedstock resources. in the sensitivity study of the above-mentioned case, the results show the power generation efficiency obviously affects the pollutant emissions. in detail, there exists about a . % or . % increase when the power generation efficiency decreases by % or . % from the base of . %, which is applied in the greet.net ; however, the emissions are reduced by about . % or . % when the efficiency increases by % or . %. . conclusions the energy crisis and reduction of ghg are critical issues that have to be solved. renewable biomass, especially lignocellulosic biomass, is abundant and complementary to non-renewable fossil resources. many technologies are developed to derive biodiesel, bioethanol, or generate electricity from non-food biomass. currently, the derivation technologies of biofuel from biomass are not mature, although they have started in some pioneer plants. biomass combustion is relatively easy and is widely applied in many countries. many case studies illustrated that lca is effective to quantify the environmental impacts of power generation from biomass. lca includes all the stages, from cradle-to-grave, along the whole process, from planting or collecting lignocellulosic biomass to electricity generation in biomass-only based or co-firing plants. the evaluations of lignocellulosic biomass for power generation are complicated with different options in lca. the analysis results of lca vary with different feedstocks, feedstock transportation, burning technologies applied to different plant scales, and ghg emissions. although power generation from lignocellulosic biomass is a general carbon neutralization process, the overall carbon footprint depends on many factors, such as different inputs related to different feedstocks, feedstock transportation, and the methods of electricity production. due to low energy density, the transportation cost of lignocellulosic biomass is more sensitive to economic efficiency of power plant location and scales of power plants shown in some lca studies. lca has also been used to quantify the ghg emission savings of power generation from biomass by comparing the emissions with a reference energy generation system from coal, fossil fuel, or natural gas. overall, . % to % savings can be achieved with different feedstocks, such as agricultural residues, grass, and wood. the results of the case study, fed with different lignocellulosic biomass, such as forestry residue, miscanthus, willow, poplar, and switchgrass, show that the lowest ghg reductions were achieved at the willow power plant. compared to power generation from coal or fossil fuels, the economic efficiency of lignocellulosic biomass is generally lower. the total cost of power generation, based on lignocellulosic biomass, varies with the inputs of feedstocks, transportation distance, and the costs on power plants. direct burning as a mature technology is globally used, and some other methods are being demonstrated and developed. in the short term, the barriers to widely use biomass for power generation are cost, low conversion efficiency, and feedstock availability. in the long term, the future of bio-power generation will depend on the urgency of greenhouse effects and energy crisis, advanced technology development of feedstock cultivation, and efficient burning methods, carbon capture, and storage, as well as the competition with the conversion efficiency of biomass into biofuel, such as bioethanol or biodiesel. sustainability , acknowledgments this work was supported by the us national science foundation through the crest center for energy and environmental sustainability (cees) at prairie view a&m university, award number . author contributions xinhua shen primarily worked on the project and prepared the initial draft of the manuscript under the guidance of raghava r. kommalapati. ziaul huque is a collaborator on the project. both kommalapati and huque contributed in revising and preparing the final draft of the manuscript. conflicts of interest the authors declare no conflict of interest. references . keshwani, d.r.; cheng, j.j. switchgrass for bioethanol and other value-added applications: a review. bioresource technol. , , – . . de paula gomes, m.s.; muylaert de araujo, m.s. bio-fuels production and the environmental indicators. renew. sust. energ. rev. , , – . . ramirez, j.a.; brown, r.j.; rainey, t.j. a review of hydrothermal liquefaction bio-crude properties and prospects for upgrading to 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Е К О Н О М іК А 	 	м ех а н із м и р ег ул ю в а н н я е ко н о м ік и БІЗНЕСІНФОРМ № ’ www.business-inform.net УДК . . . ( ) КОНцЕпТуАльНІ пРИНцИпИ РОЗРОбКИ ТА РЕгулювАННя ЕНЕРгЕТИчНОї пОлІТИКИ уКРАїНИ НА КОНКуРЕНТОСпРОМОЖНОМу РІвНІ © кЛимчУк о. в. УДК . . . ( ) Климчук О. В. Концептуальні принципи розробки та регулювання енергетичної політики України на конкурентоспроможному рівні Мета статті полягає в дослідженні сучасних тенденцій регулятивної політики на світовому енергетичному ринку та виявленні дієвих шляхів зростання енергоефективності економіки України. Здійснено аналіз основних напрямків розвитку енергетичної політики у світі та встановлено пріоритетний напрямок розвитку енергетики України на основі біопаливної індустрії. Обґрунтована актуальність того, що в Україні одним із головних напрямків подолання енергетичної кризи, забезпечення оздоровлення економіки та стійкого зростання валового внутрішнього про- дукту є перехід до промислового використання біопалив. Процес виробництва та споживання біопалив потрібно розглядати як засіб підвищення рівня децентралізації при забезпеченні енергоносіями. Зазначено, що державі необхідно провадити інформаційну підтримку виробників біопа- лива, визначаючи їх ринковий асортимент та рекомендуючи найвигідніших ділових партнерів. Збільшення виробництва біопалив в Україні буде виступати фундаментальним фактором у забезпеченні міжнародної конкурентоспроможності національної економіки, а також її зростання на інноваційних засадах. Ключові слова: економіка, енергетичний ринок, енергетична політика, державне регулювання, конкурентоспроможність, біопаливо. Бібл.: . Климчук Олександр Васильович – кандидат сільськогосподарських наук, доцент, доцент кафедри адміністративного менеджменту та альтер- нативних джерел енергії, Вінницький національний аграрний університет (вул. Сонячна, , Вінниця, , Україна) e-mail: klimchuk- @mail.ru УДК . . . ( ) Климчук А. В. Концептуальные принципы разработки и регулирования энергетической политики Украины на конкурентоспособном уровне Цель статьи заключается в исследовании современных тенденций ре- гуляторной политики на мировом энергетическом рынке и выявлении действенных путей роста энергоэффективности экономики Украины. Осуществлен анализ основных направлений развития энергетической политики в мире и установлено приоритетное направление разви- тия энергетики Украины на основе биотопливной индустрии. Обосно- вана актуальность того, что в Украине одним из главных направле- ний преодоления энергетического кризиса, обеспечения оздоровления экономики и устойчивого роста валового внутреннего продукта яв- ляется переход к промышленному использованию биотоплива. Про- цесс производства и потребления биотоплива нужно рассматривать как средство в повышении уровня децентрализации при обеспечении энергоносителями. Определено, что государству необходимо про- водить информационную поддержку производителей биотоплива, определяя их рыночный ассортимент и рекомендуя выгодных деловых партнеров. Увеличение производства биотоплива в Украине будет выступать фундаментальным фактором в обеспечении междуна- родной конкурентоспособности национальной экономики, а также ее роста на инновационной основе. Ключевые слова: экономика, энергетический рынок, энергетическая политика, государственное регулирование, конкурентоспособность, биотопливо. Библ.: . Климчук Александр Васильевич – кандидат сельскохозяйственных наук, доцент, доцент кафедры административного менеджмента и альтернативных источников энергии, Винницкий национальный аграрный университет (ул. Солнечная, , Винница, , Украина) e-mail: klimchuk- @mail.ru udc . . . ( ) klymchuk o. v. conceptual principles for developing and regulating the energy policy of ukraine at a competitive level the article is aimed at studying the current trends of regulatory policy in the global energy market and identifying potent ways for energy efficiency growth in terms of the ukrainian economy. an analysis of the main trends of energy policy development in the world has been carried out and a pri- ority direction for the development of ukrainian energy on the basis of the biofuel industry has been determined. the article substantiates actuality of the matter that one of the main directions of overcoming the energy crisis in ukraine, along with ensuring recovery and sustainable growth of the gross domestic product, is transition to the industrial use of biofuels. the process of production and consumption of biofuels must be seen as a means to raise the level of decentralization, while ensuring energy sources. it is determined that the state must provide information support for producers of biofuels, defining their market range and encouraging beneficial business partners. increased production of biofuels in ukraine will serve as a fundamental factor in achieving international competitiveness of the national economy, as well as its growth on innovation basis. keywords: economy, energy market, energy policy, the state regulation, com- petitiveness, biofuels. bibl.: . klymchuk oleksandr v. – phd (agriculture), associate professor, associate professor of the department of the administrative management and alterna- tive energy sources, vinnitsa national agrarian university ( soniachna str., vinnytsia, , ukraine) e-mail: klimchuk- @mail.ru Конкурентоспроможність країни залежить, перш за все, від двох груп факторів: кількості та яко-сті наявних у її розпорядженні ресурсів (трудові, природні, інфраструктурні, технологічні, інформаційні та культурні), а також ефективності уряду, що розпоря- джається цими ресурсами. Існують великі відмінності в моделях конкурентоспроможності кожної країни, тому що жодна країна у світі не може бути конкурентоспро- можною у всіх або хоча б у більшості галузей. Зрештою деякі країни досягають успіху лише в певних галузях, оскільки їх внутрішні умови є найбільш сприятливими, динамічними та перспективними, а конкурентоспро- можність окремої країни залежить від схильності її про- мисловості до інновацій та модернізації [ ]. Одне з пріоритетних завдань світової економі- ки полягає в суттєвому підвищенні ефективності про- мислового виробництва та споживання енергетичних ресурсів. Наразі енергетична система та її політика, з точки зору безпеки постачання і глобальних змін кліма- ту, жодною мірою не є далекоглядними. Яку б енергетич- http://www.business-inform.net Е К О Н О М ІК А 	 	м ех а н із м и р ег ул ю в а н н я е ко н о м ік и БІЗНЕСІНФОРМ № ’ www.business-inform.net ну систему ми не розглядали – всюди потрібні нові інве- стиційні ресурси для задоволення прогнозованих потреб, пошуку нових джерел енергії, оновлення інфраструктури та техніки. Досить очевидним виступає той факт, що для створення надійного та перспективного енергетичного сектора потрібно постійно знаходити все нові шляхи. Сучасна політика і ринкові тенденції у всьому сві- тові досить швидко та кардинально змінюються. У пер- спективі маловуглецева та екологічно безпечна енер- гетика не тільки можлива, вона навіть вигідніша, ніж продовження політики споживання традиційних енер- гоносіїв. Однак майбутнє енергетики не має полягати в повній або частковій заміні однієї шкідливої технології на іншу, менш небезпечну. Потрібна розробка нової, набагато ефективнішої системи, за якої значно покра- щиться не лише використання енергії, але й виробни- цтво, перетворення та транспортування енергетичних ресурсів. Тут цілком слушно згадати виступ грудня р. президента США Барака Обами: «...Ми знаємо, що лідером ХХІ століття стане та країна, якій вдасться використовувати енергію екологічно безпечних, віднов- люваних джерел» [ ]. Сучасні процеси глобалізації світової економіки не залишають осторонь практично жодну з країн нашої планети, а тому формування і функціону- вання національних ринків, у тому числі енергетично- го, так чи інакше відбувається в тісному взаємозв’язку з розвитком продуктивних сил і суспільних відносин дер- жави. Економічно розвинуті країни світу вказують на те, що вони одностайно підтримують принципи Енергетич- ної хартії, а також Глобальної хартії у формуванні розви- тку сталої енергетики. Пріоритетним завданням вказа- них міждержавних угод є відкриття всіма країнами сво- їх енергетичних секторів для встановлення міжнародної конкуренції. Внаслідок цього потрібно провести ретель- ний облік усіх форм і видів енергії, а всі надані субсидії та виникаючі зовнішні ефекти, пов’язані з кожним за- пропонованим варіантом, необхідно повністю включа- ти в економічні розрахунки та віддзеркалювати на сумі конкурсної пропозиції. На доданок до цього, буде знач- ним позитивом, якщо промислово розвинуті країни по- чнуть тісно співпрацювати з країнами «третього світу» в галузі становлення та розвитку відновлюваних джерел енергії для задоволення енергетичних потреб цих країн, враховуючи екологічні вимоги. Доцільно також розширити вільну конкуренцію при проголошенні тендерів на будівництво потужних енергетичних об’єктів, включаючи різні види енерге- тики, що дозволить порівнювати різноманітні варіанти та вибирати найкраще джерело отримання енергії за критеріями рентабельності та екологічності. Для цьо- го потрібно в комплексі використовувати державно- владні регулятори – нормативно-правова база, владні структури загальнодержавного і регіонального рівнів та ринкові механізми – закони ринку (попит, пропозиція, конкуренція, кон’юнктура), виробники, споживачі, інф- раструктура, професійні та міжпрофесійні об’єднання. На думку Є. Боброва, ринковий підхід до вирішення питання розробки енергетичної політики країни бажаний, але далеко не завжди ефективний. У міру вдосконалення ринкових структур і переходу до розвинутих форм ринку державне регулювання багато в чому замінюється різно- манітними непрямими регуляторами, але сукупна регу- лювальна роль держави постійно збільшується. Тому, не- зважаючи на те, що державна енергетична політика дедалі більше реалізується через спільну енергетичну стратегію держави і бізнесу, включаючи окремі енергетичні компанії, її сукупне значення невпинно підвищується. Це підтвер- джується практикою ряду країн, що мають як індикативні, так і затверджені – -річні плани соціально-економічного та науково-технічного розвитку, які багато в чому побу- довані на регулювальній ролі структурного, промислово- енергетичного, науково-технічного, інвестиційного, кре - дитно-фінансового, зовнішньоекономічного, екологічно- го та інших видів політики. Багато експертів вважають, що енергетична стратегія країни повинна містити не кон- кретні цифри, а в основному тільки цілі, принципи і мето- ди. Єдине, що прийнятно, – це граничний нормативний рівень рентабельності природних монополій і конкретних параметрів у екологічному розділі, але для цього потріб- ний твердий державний контроль. Щодо різних прогнозів розвитку енергетики, особливо довгострокових, то досвід показує, що вони є об’єктивно недостовірними [ ]. С. Єрмілов зазначає, що формування стійких за- гальносвітових тенденцій до зростання цін на вугле- водневі енергоресурси, посилення негативного впливу життєдіяльності людини на стан екологічної системи, а також подальше загострення конкуренції національ- них економік під дією глобалізаційних процесів актуалі- зували проблему ефективного державного регулювання країн в енергетичній сфері та визначили його сучасні пріоритети. Дана проблема загострилася і для нашої держави. Лише підпорядковуючи власну енергетичну політику таким цілям, як гарантування енергобезпеки, зростання енергоефективності та досягнення еколо- гічного збалансування на макрорівні, Україна зможе адекватно реагувати на зазначені виклики сучасності та нівелювати вплив несприятливих коливань зовнішньої та внутрішньої кон’юнктури на національну конкурен- тоспроможність. З огляду на поточний рівень техноло- гічного розвитку й енергозалежності нашої країни від зовнішніх джерел, найголовнішим фактором системної конкурентоспроможності в Україні є ефективність ви- користання паливно-енергетичних ресурсів [ ]. Економічна безпека України вимагає наявності до-статньої кількості паливно-енергетичних ресурсів для реалізації відтворюваних процесів у всіх сфе- рах масового використання суспільно корисної праці, забезпечення стабільності розвитку суспільства та під- тримання незалежності держави щодо самостійного формування внутрішньої та зовнішньої політики. Під час вибору джерел енергії та технологій їх отримання необхідно керуватися вартістю повного циклу енерго- постачання (виробництво, транспортування, розподіл та споживання енергії), включаючи витрати на охорону здоров’я та навколишнє середовища. Система ефектив- ного управління виробничими процесами має врахову- вати територіальні особливості та здійснювати спожи- http://www.business-inform.net Е К О Н О М іК А 	 	м ех а н із м и р ег ул ю в а н н я е ко н о м ік и БІЗНЕСІНФОРМ № ’ www.business-inform.net вання мінімальної виробничо-доцільної кількості енер- горесурсів, надаючи пріоритет біопаливам [ ]. У світовому масштабі Україна має найбільш енер-гозатратну промисловість, тому конкуренто-здатність вітчизняної продукції напряму залежить від цін на традиційні енергоносії, вартість яких постійно зростає. Умови сьогодення вказують на те, що Україна характеризується нераціональною структурою промис- лового використання енергетичних ресурсів, тому до- сить актуальною в теоретичному та практичному плані є проблема підвищення ефективності управління в спо- живанні енергії та зменшенні показників енергомістко- сті виробленої продукції. До того ж, сучасна ситуація в паливно-енергетичному комплексі нашої держави від- значається інтенсивним зростанням імпорту енергоре- сурсів, який за вартісними показниками суттєво переви- щує обсяги видобутку та експорту власних енергоносіїв. Загальною тенденцією на паливно-енергетичному ринку нашої держави є невпинний процес вирівнювання цін на природний газ, нафту та продукти нафтопереробки зі світовими показниками, тобто спостерігається до- сягнення паритетності цін внутрішнього та зовнішнього ринків енергоносіїв. С. Єрмілов вказує на те, що в цілому актуальність подальшої демонополізації та поліпшення конкурент- ного середовища діяльності галузей українського ПЕК (насамперед, у напрямі розбудови конкурентних енер- горинків) для України з часом лише зростає. Недоско- нале державне регулювання в її енергетичній сфері зу- мовило те, що, незважаючи на всі проведені реформи вітчизняного енергетичного сектора, й досі внутрішні ринки енергоресурсів України (крім, з певними застере- женнями, ринку нафтопродуктів і ринку послуг з поста- чання електроенергії) не є конкурентними, оскільки на жодному з них не забезпечується вільний вибір контр- агентів, конкурентні засади господарської діяльності для виробників – суб’єктів ринку не стали домінуючи- ми, а дія ринкових механізмів ціноутворення практично нівелюється частим централізовано-адміністративним впливом [ ]. Як наслідок, в Україні необхідно створити інституції громадянського суспільства та цивілізованої ринкової економіки в оптимальному поєднанні з дер- жавним регулюванням. В. Микитенко акцентує увагу на тому, що науково обґрунтована стратегія збалансованого розвитку еко- номіки стає одним із основних засобів запобігання ви- никненню можливих загроз безперебійному енергоза- безпеченню всіх виробничих сфер держави. Політика, направлена на досягнення оптимальної енергоефектив- ності економіки будь-якої держави, являє собою склад- ну комбінацію внутрішньо- та зовнішньоорієнтованих заходів, які визначають сутнісні особливості країни у конкретний момент її соціально-економічного і політич- ного розвитку. Підвищення ефективності використання енергоресурсів спрямує десятки мільярдів гривень на рік в інші економічні та соціальні сфери, створить мож- ливість для зниження собівартості продукції, збільшен- ня обігових коштів, зростання заробітної платні, субси- дій, наповнення бюджетів усіх рівнів. Окрім того, це ще й певний інструментарій удосконалення управління в різних галузях національної економіки [ ]. У результаті проведення комплексної оцінки впли- ву окремих чинників на енергоефективність економіки було встановлено, що найбільше впливають на даний агрегований показник політико-економічні фактори. Їхня негативна дія спричинює низький рівень енерго- ефективності, однак, застосовуючи обґрунтовані управ- лінські заходи, цей рівень можна значно підвищити [ ]. Отже, найактуальнішою проблемою державної еко - номічної політики є її здатність забезпечити умови ста- більного економічного розвитку, а найважливіша скла- дова економічного розвитку – економічне зростання. Тому метою інтенсифікації регуляторних зусиль є макси- мізація обсягів національного виробництва, що є єдиним шляхом для підвищення рівня споживання матеріаль- них благ і задоволення постійно зростаючих людських потреб у рамках існуючого технологічного способу ви- робництва. Безумовно, проблематика економічного роз- витку є значно ширшою, однак її вирішення пов’язане з чітким визначенням потенціалу існуючих виробничих можливостей. Як наслідок – потрібно розробити ціліс- ний економічний механізм функціонування енергозбе- рігаючої політики із регламентованими заходами еко- номічного, правового і адміністративного спрямування, а також створити умови, коли енергозбереження та ве- личина отриманого прибутку суб’єктами господарюван- ня будуть розглядатися як взаємозалежні й односпря- мовані вектори, незважаючи на високі рівні витрат при впровадженні енергозберігаючих технологій. При цьому необхідно врегулювати ціни на па ливно-енергетичні ресурси та привести їх у відповідність із реальними витратами країни. Формуючи ціни на енергоносії, доцільно враховувати економічні збитки від їх негативного впливу на навколишнє середовище, що зумовить не тільки їх раціональне використання, але й встановить економічну межу доцільності їх видобування. При управлінні важливість цінового та тарифного факто- рів підкреслює той факт, що майже у всіх західних країнах бюджет держави отримує значні прибутки з високих цін на окремі види енергоносіїв, зокрема бензин і дизельне паливо. Тому система цін на паливно-енергетичні ресур- си повинна враховувати фінансові, економічні й бюджет- ні умови та екологічні вимоги. Світовий та вітчизняний досвід вказує на те, що ефективне використання ринкової моделі регулювання в економіці, а також у паливно-енергетичному комп- лексі, можливе лише за умов створення дієвої системи правового та нормативного забезпечення, яке виступає запорукою впровадження ринкових механізмів регулю- вання. На жаль, через цілу низку як об’єктивних, так і суб’єктивних причин синхронізувати дані процеси в Україні не вдалося, що стало одним із головних факторів постійного загострення ситуації в економіці країни та її паливно-енергетичному комплексі. Динамічні та глибо- кі зміни в економіці й енергетиці країни потребують по- стійного вдосконалення існуючої нормативно-правової бази та її подальшого розвитку відповідно до нових еко- номічних та соціально-політичних умов. http://www.business-inform.net Е К О Н О М ІК А 	 	м ех а н із м и р ег ул ю в а н н я е ко н о м ік и БІЗНЕСІНФОРМ № ’ www.business-inform.net З огляду останніх подій, у зв’язку з кардиналь- ними змінами в політичному укладі та економічній кон’юнктурі, потрібно розробляти новітні системні під- ходи при розв’язанні проблемних питань у напрямку розвитку національної політики із забезпечення енер- гоносіями, яка на сьогодні є однією з найслабших ла- нок державного регулювання в Україні. Простежують- ся знач ні невідповідності у формуванні та подальшому функціонуванні нормативно-правової бази із законо- давчими нормативами ЄС щодо раціонального викори- стання паливно-енергетичних ресурсів, обмеженість яких підвищується через неузгодженість між централі- зованим та регіональним розподілом. Т. В. Плахтій та В. Ю. Драчук вказують на те, що законодавче регулювання на рівні держави із застосу- ванням різних підходів у стимулюванні виробників та споживачів конкретної галузі народного господарства свідчить про зацікавленість у позитивних результатах та розширенням конкретного ринку на перспективу. Сто- совно енергетичної галузі, яка займається виробництвом біопалива, також передбачено ряд податкових важелів з метою зниження податкового тиску на суб’єктів, які при- четні до даного процесу. Встановлення особливих підхо- дів у оподаткуванні є аргументом для визначення важли- вої ролі біоенергетичної галузі для України в цілому [ ]. Під час здійснення системного дослідження ви-робничого потенціалу біоенергетичної галузі необхідно провести комплексний аналіз реко- мендованого обсягу виробництва конкурентоспромож- ної кількості біопалив (оптимізованого за асортиментом і періодом виготовлення), установлення можливостей його нарощування залежно від існуючої кон’юнктури ринку та зони переходу на новий обсяг робіт, послуг і ви- робленої продукції. Даний аналіз паралельно потребує системного вивчення ринку засобів виробництва, ринку капіталу, ринку робочої сили тощо. На основі комплекс- ної оцінки результатів проведених досліджень одержу- ють індикативні параметри виробничої програми, що дозволяє сформувати портфель замовлень у біопалив- ному виробництві, враховуючи попит на біопалива, їх конкурентоспроможність, критичну масу продажів, можливості укладання контрактів постачання на менш вигідних умовах, діапазон коливання цін на виготовлену продукцію, сезонність виробництва, напруженість ви- робничої програми та інші регіональні аспекти. Одним із головних напрямків подолання енерге- тичної кризи, забезпечення оздоровлення економіки та стійкого зростання валового внутрішнього продук- ту є перехід до промислового використання біопалив. Процес виробництва та споживання біопалив потрібно розглядати як засіб у підвищенні рівня децентралізації при забезпеченні енергоносіями, що сприятиме приско- ренню розвитку та впровадження відповідної техніки та технологій. Розвиток національного біопаливного виробництва повинен підвищити енергоефективність економіки України до показників розвинутих країн світу. Споживання різних видів біологічних палив має прискорити темпи зниження енергомісткості ВВП, у ре - зультаті чого в коротко- або середньостроковій пер- спективі відбудеться зростання конкурентоздатності вітчизняного продукту на світових ринках. Реалізація належного державного регулювання біо- паливним виробництвом стримується, передусім, від- сутністю його організаційного механізму та правового забезпечення. Йдеться про методичне й організаційне забезпечення роботи цього механізму, про професійне розв’язання кожної з виникаючих проблем і доведення від ідеї та загальної конструкції до практичної реаліза- ції. Такі завдання в повному обсязі можуть виконувати ринкова інфраструктура та відповідні урядові структу- ри. Сучасні методи державного регулювання біопалив- ним виробництвом потрібно спрямовувати на форму- вання ефективних вертикально інтегрованих структур, забезпечуючи їх наповнення необхідними інноваційно- інвестиційними ресурсами. Дані методи повинні базу- ватися на пошуку і реалізації синергійного потенціалу інтеграційних стратегій та забезпечувати формуван- ня довгострокових конкурентних переваг. Українська енергетична система має стати невід’ємною складовою європейського енергетичного ринку, а одним із важли- вих подальших кроків є ретельний економічний аналіз та створення відповідної математичної моделі розвитку біопаливної галузі. ВИСНОВКИ Однією з найважливіших складових добробуту в цивілізованих державах є забезпечення громадян і ком- паній необхідними енергоресурсами. Запорукою реалі- зації цієї мети має стати надійне, економічно обґрунто- ване та екологічно безпечне задоволення потреб насе- лення та економіки в енергетичних продуктах. Замість підтримки екстенсивного розвитку, яким економіка України рухалася протягом десятиліть, енергетика по- винна перейти на ефективне забезпечення сталого роз- витку економіки [ ], розвиваючи також виробництво біопалив як особливого виду інноваційної діяльності. Для цього в нашій країні необхідно проводити діє- ві реформи в напрямку розгортання біопаливного ви- робництва, щоб досягти європейських стандартів. Не потрібно розраховувати на бюджетні кошти при вироб- ництві біопалива, проте державі необхідно провадити інформаційну підтримку виробників біопалива, визнача- ючи їх ринковий асортимент і рекомендувати найвигід- ніших ділових партнерів – від постачання біосировини і комплектуючих до реалізації готового біопалива. Біо- паливні підприємства повинні забезпечувати весь тех- нологічний цикл виробництва біологічних видів палива, включаючи їх подальшу економічно вигідну реалізацію. Збільшення виробництва біопалив в Україні буде висту- пати фундаментальним фактором у забезпеченні міжна- родної конкурентоспроможності національної економі- ки, а також її зростання на інноваційних засадах.  ЛІтЕРАтУРА . портер М. Э. Конкуренция / М. Э. Портер / Пер. с англ. – М. : Издательский дом «Вильямс», . – с. . Ядерная энергия: мифы и реальность. Тематические исследования по ядерной энергетике / Э. Фрогатт, О. Нассауэр, http://www.business-inform.net Е К О Н О М іК А 	 	м ех а н із м и р ег ул ю в а н н я е ко н о м ік и БІЗНЕСІНФОРМ № ’ www.business-inform.net М. Шнайдер и др. – Изд. второе, перераб. и доп. – Ровно, . – с. . Бобров Є. Невуглеводнева енергетична політика України у світовому контексті / Є. Бобров // Економіка України. – . – № . – С. – . . Єрмілов С. Проблеми та шляхи удосконалення дер- жавної політики України у галузі енергозбереження / С. Єрмі- лов // Економіка України. – . – № . – С. – . . Климчук О. В. Економічне значення та оптимізація використання енергетичних ресурсів / О. В. Климчук // Вісник аграрної науки. – . – № . – С. – . . Єрмілов С. Формування конкурентних енергоринків в Україні / С. Єрмілов // Економіка України. – . – № . – С. – . . Микитенко В. Енергоефективність національної еко- номіки: соціально-економічні аспекти / В. Микитенко // Вісник НАН України. – . – № . – С. – . . Суходоля О. М. Енергоефективність економіки в кон- тексті національної безпеки: методологія та механізми реаліза- ції / О. М. Суходоля. – К. : Вид-во НАДУ, . – с. . плахтій т. В. Законодавче регулювання податкового стимулювання вирощування біоенергетичних культур, вироб- ництва і використання біопалива / Т. В. Плахтій, В. Ю. Драчук // Збірник наукових праць Інституту біоенергетичних культур і цукрових буряків. – К., . – Вип. . – С. – . . шостак Л. Енергозабезпечення України у міжнарод- них економічних відносинах / Л. Шостак, О. 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( ): - . http://www.business-inform.net microsoft word - v - - .doc abstract—this study examines causal link between energy use and economic growth for five south asian countries over period - . panel cointegration, ecm and fmols are applied for short and long run estimates. in short run unidirectional causality from per capita gdp to per capita energy consumption is found, but not vice versa. in long run one percent increase in per capita energy consumption tend to decrease . percent per capita gdp. i.e. energy use discourage economic growth. this short and long run relationship indicate energy shortage crisis in south asia due to increased energy use coupled with insufficient energy supply. beside this long run estimated coefficient of error term suggest that short term adjustment to equilibrium are driven by adjustment back to long run equilibrium. moreover, per capita energy consumption is responsive to adjustment back to equilibrium and it takes years approximately. it specifies long run feedback between both variables. keywords—energy consumption, income, panel co-integration, causality. i. introduction nergy is the engine of economic growth, as many production and consumption activities involve energy as basic input. on production side, conventionally, economists since adam smith have talked about land, labor, and capital as major inputs for economic activity. these inputs were significant ingredients of agrarian economies of th and th centuries. however, in th century, the growth of industrial nations has observed a fourth major input that is energy. on consumption side, in the keynesian framework where consumption and income are significantly correlated, similarly energy consumption in all forms drives economic productivity. it leads to economic growth and prosperity which ensures expansion of the economy in terms of higher gdp and gdp per capita. the preeminent case of the primary role of energy that it plays an important role in the economy was found in s energy crisis. in st oil crisis oapec restrained oil consignment to us and other countries as they supported israel in conflict. restricted supply got much higher prices s. noor is with the economics department, gc university lahore, pakistan as research scholar (phone: - ; e-mail: saeedanoor@gmail.com). m. w. siddiqi is with economics department, gc university lahore, pakistan as associate professor (ph no. - ; e-mail: mwsiddiqi@gmail.com). within few months. it inversely affected the us economy by influencing pressing demand of energy by high cost and scarcity of oil. in us alone, in gdp sharply turned down after two decades of steady growth. moreover, at macro level economies have faced both inflationary and deflationary impacts on domestic economies [ ]. similarly, in nd oil crisis protests severely disrupted the iranian oil sector and production being greatly curtailed and exports suspended. later, oil exports were again started under the new regime. these were inconsistent and at a lower volume, which pushed up prices. it resulted in very high prices than expected under normal circumstances [ ]. therefore, the s energy crisis attracted the analysts to investigate the relationship between energy consumption and economic growth, as it was argued that energy consumption directly causes gdp growth. since the end of s, many studies [ ], [ ], [ ] have been conducted to support the arguments which suggest that energy use is highly positively correlated with gdp growth. but empirical evidence is varying and conflicting about direction of causality, whether economic growth leads to energy consumption or energy use boosts up the gdp growth. from policy perspective, based on the direction of causality there are important policy implications. because, the energy conservation policy may or may not be taken, depends on the direction of causality [ ]. unidirectional causality running from gdp to ec implies that income is the initial receptor of exogenous shocks and equilibrium is restored through adjustment in energy consumption. these are less energy dependent economies and energy conservation policies may be implemented without adverse effects on economic growth and employment [ ]. on the other hand, if causality runs from energy consumption to gdp then it implies that the economy is energy dependent and energy consumption measures may stimulate economic growth [ ]. bidirectional causality indicates that both energy consumption and high level of economic activity mutually persuade each other. finally, no- causality between energy consumption and economic growth referred as “neutrality hypothesis” [ ] implies that energy conservation measure may pursued without affecting the economy. south asia is important to world energy markets as it experiencing rapid energy demand growth. the primary energy consumption and economic growth in south asian countries: a co-integrated panel analysis s. noor and m. w. siddiqi e world academy of science, engineering and technology international journal of energy and power engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e ne rg y an d p ow er e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/energy-consumption-and-economic-growth-in-south-asian-countries:-a-co-integrated-panel-analysis/ http://scholar.waset.org/ - / energy consumption has increase nearly percent between and in south asia. in south asia, accounted for approximately . percent of world commercial energy consumption up from . percent in [ ]. therefore, south asian nations are facing rapidly increasing demand for energy coupled with insufficient energy supply. they are energy-deficit countries and fighting with energy shortfalls in the form of recurrent, costly, and widespread electricity outages. because of the economic and political effects arising from such shortfalls, improving the supply of energy, particularly the supply of electricity, is an important priority of regional governments. to avoid energy crisis and efficient utilization of energy recourses, usaid south asia regional initiative for energy (sari/energy) program has been in operation since . afghanistan and pakistan joined the sari/energy program in . the usaid is an eight country program that promotes regional energy security through three activities areas: ( ) cross border energy trade, ( ) energy market formation, and ( ) regional clean energy development. through these activities, sari/energy facilitates more efficient regional energy resource utilization, improves the environmental impacts of energy production, and increases regional access to energy, works toward transparent and profitable energy practices. sari/energy countries include: afghanistan, bangladesh, bhutan, india, maldives, nepal, pakistan, and sri lanka [ ]. the following sections of the paper set out literature review, model, data, empirical results and conclusion, policy implications. ii. literature review the pioneer study by kraft and kraft [ ] found evidence of unidirectional causality from gnp growth to energy consumption in case of the us for period - . yu and choi [ ], yu and hwang [ ] and erol and yu[ ] found no link for us economy when they used granger method. however, yu and hwang [ ] detected that energy consumption negatively affected employment by using sim’s techniques. yu and choi [ ] also deducted causality from gdp to energy in republic of korea, reversed in the case of the philippines. masih and masih [ ] found bidirectional causality in pakistan. aqeel and butt [ ] and zahid [ ] supported existence of unidirectional causality from gdp to energy consumption while inverse causality evidence is found by khan and qayyum [ ]. zahid [ ] also found unidirectional causality from gdp to energy consumption for bangladesh and srilanka. in case of india asafu-ajaye [ ] and khan and qayyum [ ] found unidirectional causality from energy consumption to income while neutrality hypothesis is supported by zahid [ ] similarly, unidirectional casualty from economic growth to energy consumption is also found by asafu-adjaye [ ] in philippine and thailand, wolde-rafael [ ] in egypt, gabon and morocco, yoo [ ] and tang [ ] in malaysia and apergis and payne [ ] in six central american countries. there are mixed results from one study to another for individual countries and regions. thus, this study is aimed to investigate the core relationship between per capita energy consumption and per capita gdp for five selected south asian countries. iii. data and variables the study uses panel data consists of south asian countries (n= .... ) for the period to (t= .... ). the selected countries are bangladesh (bgd), india (ind), nepal (npl), pakistan (pak) and srilanka (lka). the variables used in the model are gross domestic product per capita (current us $), per capita energy use (kiloton of oil equivalent), gross fixed capital formation (current us $) and total labor force. the data was sourced from world development indicators ( ) [ ]. iv. model specification the following multifactor neoclassical production function framework proposed by ghali and el-sakka [ ] is used to find out the relation between different factors of production (including energy) and output: ln { ln ( , , ) } ( )gdp f ec k l= the double ln model is used to represent the growth model, so that all variables can be explained in growth terms. the panel version of equation ( ) can be written as follows: ) (lnlnlnln εα βββ tiiiiiiiii lkecgdp ++++= where, i is cross-sections. t denotes time period. εit is the error term with the usual statistical properties while α and β are coefficients. it is difficult to obtain significant t-ratio or f-statistics for regressions while estimating samples with very few observations. it is common problem of time-series when annual data is used for estimations, since there are very few annual series which extended more than fifty years. to overcome this problem an efficient solution is to pool data into a panel of time series from different cross-sectional units. hence, use of panel data has advantage that it can exploit both the cross sectional and time series dimensions of data and provide more efficient estimations of parameters by considering broader sources of variation [ ]. v. methodology to estimate ( ) study uses panel cointegration framework. the cointegration analysis of panel data consists of four steps: a. panel unit root tests the purpose of unit root tests is to check the stationary of data. four different statistics proposed by phillips-perron [ ], maddala and wu [ ], levin et al. [ ] and im et al. [ ] are adopted each claiming more power against the null of unit root in a variable. world academy of science, engineering and technology international journal of energy and power engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e ne rg y an d p ow er e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/energy-consumption-and-economic-growth-in-south-asian-countries:-a-co-integrated-panel-analysis/ http://scholar.waset.org/ - / b. cointegration tests cointegration test is primarily used to investigate the problem of spurious regression, which exists only in the presence of non-stationary. therefore after application of unit root tests, if each of the variables is stationary then issue arises whether there exists a long-run equilibrium relationship between the variables. for this heterogeneous panel cointegration test developed by pedroni [ ] is employed. it allows the cointegration vector to vary across different sections of the panel, and also for heterogeneity in errors across cross-sectional units. the kao [ ] test is also used to check cointegration of data. c. panel fully modified ols estimates the study estimates the long run relationship by using fully modified ordinary least square (fmols) technique developed by pedroni [ ] for heterogeneous cointegrated panels. d. granger causality test finally, once the panel cointegration is implemented, a panel error correction model (ecm) is established to study short-run and long-run causalities between gdp per capita and ec per capita. the two-step procedure of engle-granger [ ] is performed as: firstly, estimation of the long-run model for ( ) in order to obtain the estimated residuals εit. secondly, to estimate the granger causality model with a dynamic error correction: ) (lnlnln lnln μθθ θθελθ tikti k kikti k kikti k kikti k kitiijti lkec gdpgdp +Δ+Δ+Δ +Δ++=Δ −−− −− ∑∑ ∑∑ ) (lnlnln lnln μθθ θθελθ tikti k kikti k kikti k kikti k kitiijti lkec gdpec +Δ+Δ+Δ +Δ++=Δ −−− −− ∑∑ ∑∑ ) (lnlnln lnln μθθ θθελθ tikti k kikti k kikti k kikti k kitiijti lkec gdpk +Δ+Δ+Δ +Δ++=Δ −−− −− ∑∑ ∑∑ ) (lnlnln lnln μθθ θθελθ tikti k kikti k kikti k kikti k kitiijti lkec gdpl +Δ+Δ+Δ +Δ++=Δ −−− −− ∑∑ ∑∑ where, Δ denotes first differencing. λ is the lag length and is chosen optimally for each country using a step-down procedure up to a maximum of two lags. the sources of causation between gdp per capita and ec per capita are identified by testing for the significance of the coefficients of dependent variables in ( ) and ( ). for short- run causality, study test h : θ i,k = for all i and k in ( ) or h : θ i,k = for all i and k in ( ). while, the long-run causality is tested by looking at the significance of speed of adjustment λ , which is the coefficient of the error correction term, εi,t- . the significance of λ indicates the long-run relationship of the cointegrated process, and so movements along this path can be considered permanent. for long-run causality, test h : λ i = for all i in ( ) or h : λ i = for all i in ( ) is used. similarly, sources of causation between gdp per capita and other two variables (capital and labour) are identified through ( ) and ( ). the rational to adopt these tests is; the panel unit root and panel cointegration approach avoids the problem of spurious regression through investigating the order of integration of the variables. if the variables are non-stationary, testing whether the variables are cointegrated. if the variables are cointegrated, it follows that a linear combination of the non- stationary variables will be stationary. the panel cointegration framework also has the advantage that because it tests whether there is a long-run relationship between the variables or not. it allows distinguishing between short-run and long-run impacts, which is not possible with conventional panel data analysis. vi. empirical results a. panel unit root results results of the panel root tests are reported in table i. its show that all tests do not reject the null hypothesis of non- stationary in the level form for all variables by considering both individual effect and individual linear trend effect. all tests reject null-hypothesis of non-stationary when variables are used at first difference. this implies that series of variables gdp per capita , ec per capita , k and l are integrated of order one, and i ( ) process. these results are consistence with notation that most of macroeconomics variables are non- stationary at level, but become stationary after first differencing [ ]. consequently, as pooled data is stationary at first difference, the series follow stochastic trends and therefore can be cointegrated as well. table i panel unit root tests results test statistics llc ips mw(adf) pp(fisher) a: level model specification: individual effects ln gdp . ( . ) . ( . ) . ( . ) . ( . ) ln ec . ( . ) . ( . ) . ( . ) . ( . ) ln k . ( . ) . ( . ) . ( . ) . ( . ) ln l . ( . ) . ( . ) . ( . ) . ( . ) model specification: individual effects and individual linear trends ln gdp . ( . ) . ( . ) . ( . ) . ( . ) ln ec . ( . ) . ( . ) . ( . ) . ( . ) ln k . ( . ) . ( . ) . ( . ) . ( . ) ln l . ( . ) . ( . ) . ( . ) . ( . ) b: first differences model specification: individual effects Δlngdp . ( . ) . ( . ) . ( . ) . ( . ) Δln ec . ( . ) . ( . ) . ( . ) . ( . ) Δln k . ( . ) . ( . ) . ( . ) . ( . ) Δln l . ( . ) . ( . ) . ( . ) . ( . ) model specification: individual effects and individual linear trends Δln gdp . ( . ) . ( . ) . ( . ) . ( . ) Δln ec . ( . ) . ( . ) . ( . ) . ( . ) Δln k . ( . ) . ( . ) - . ( . ) . ( . ) Δln l . ( . ) . ( . ) . ( . ) . ( . ) notes: llc, ips, mw and pp indicated the levin et al. ( ), im et al. ( ), maddala and wu ( ) and phillips-perron ( ) panel unit root and stationary tests. all tests examine the null hypothesis of non-stationary world academy of science, engineering and technology international journal of energy and power engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e ne rg y an d p ow er e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/energy-consumption-and-economic-growth-in-south-asian-countries:-a-co-integrated-panel-analysis/ http://scholar.waset.org/ - / (unit root). the four variables were grouped into one panel with sample n= , t= . the parenthesized values are the probability of rejection. probabilities for the mw (adf fisher chi-square) and pp (fisher chi-square) tests are computed using an asymptotic χ distribution, while the other tests follow the asymptotic normal distribution. b. cointegration pedroni seven tests based on residuals from ( ) are reported in table ii. results show existence of cointegration between variables at percent significant level as for all three models these reject the null of no cointegration. therefore, it is concluded that the variables are cointegrated and a long run relationship exist for group as a whole and the members of the panel. table ii heterogeneous panel cointegration results test statistics no deterministic trend deterministic intercept and trend no deterministic intercept and trend panel cointegration statistics ( within-dimension ) panel v-statistics . ( . ) . ( . ) - . ( . ) panel pp type ρ- statistics - . ( . ) - . ( . ) - . ( . ) panel pp type t- statistics - . ( . ) - . ( . ) - . ( . ) panel adf type t-statistics . ( . ) . ( . ) - . ( . ) group mean panel cointegration statistics (between-dimension) group pp type ρ-statistics - . ( . ) . ( . ) - . ( . ) group pp type t- statistics - . ( . ) - . ( . ) - . ( . ) group adf type t-statistics - . ( . ) . ( . ) . ( . ) note: this table reports pedroni ( ) residual cointegration tests. the number of lag truncations used in the calculation of statistics is fixed at . the null hypothesis is no cointegration. probability values are in parenthesis. from the kao residual cointegration result reported in table iii, strong evidence is found to reject the null hypothesis of no cointegration at one percent level of significance. therefore, it is concluded that there exist a strong evidence of long-run cointegration relationship between the variables for the multi- country panel. these results are consistent with lee [ ], sadorsky [ ] and apergis and payne [ ]. table iii kao residual cointegration test result model specification : no deterministic trend adf t-statistics - . ( . ) notes: this table reports kao ( ) residual cointegration test. the number of lag truncations used in the calculation of statistics is fixed at . the null hypothesis is no cointegration. probability values are in parenthesis and computed using asymptotic chi-square distribution. c. fmols estimates the long run estimates based on pedroni’s group mean fmols estimators for individual and panel are reported in table iv. on per country basis, the results are mix for all five countries. magnitude of coefficients denotes long-run elasticities of output with respect to energy consumption, capital and labor. in long run, elasticity of energy consumption ranges from - . (srilanka) to . (india). however for three countries (bangladesh, india and nepal), coefficient of ec per capita is significantly positive, that is an increase in energy consumption tends to promote gdp per capita, while remaining two (pakistan and srilanka) have negative elasticity which mean an increase in ec per capita tend to decrease gdp per capita in long-run. from the elasticities it can also be inferred that due to increase in ec per capita growth goes down more in pakistan rather than in sri lanka ( . > . ). moreover for individual countries it is noted that magnitude of ec per capita is larger than magnitude of k and l, it implies that energy is an important ingredient for economic growth and strong energy policies are required to attain sustained economic growth and that may vary for individual countries. table iv fully modified ols estimates (dependent variable is ∆ ln gdp) independent variables countries intercept ∆ ln ec ∆ ln k ∆ ln l bng . ( . ) . ( . )* - . (- . ) - . (- . )*** ind . ( . ) . ( . )* . ( . ) - . (- . )* npl - . (- . )* . ( . )*** . ( . ) . ( . )* pak . ( . ) - . (- . )* . ( . )* - . (- . )*** lka - . (- . )* - . (- . )* . ( . )* . ( . )* panel group . ( . )* - . (- . )** . ( . )* - . (- . )* notes: the number of lag truncations used in calculation is . the values in parentheses denote the t-statistics following a standard normal distribution. asterisk * , ** and *** indicate statistical significance at % , % and % levels, respectively. the coefficient of capital is positive and significant for countries out of . only for pakistan and srilanka it positively affects gdp per capita while for remaining countries no long-run relationship is found. the sign of labor is negative for bangladesh, india and pakistan while positive for nepal and srilanka only. for panel results of regression equation with gdp per capita as dependent variable show that coefficients of ec per capita and l are negative and statistically significant and coefficient of k is positive and significant. these results suggest that one percent increase in energy consumption per capita tends to decrease . percent gdp per capita; it implies that ec per capita discourage gdp per capita in the long-run. it may be because the south asian nations are poor in energy sector. their energy production capacity is unable to meet rising demand of energy. increase in gdp enlarges economy with the expansion of different sectors (agriculture, industries, household etc.). energy consumption also goes up in different forms in growing sectors where it is used as basic input. therefore increase in energy consumption coupled with insufficient energy supply lead to shortage, energy crisis and eventually power-cut off. that energy crisis negatively effects world academy of science, engineering and technology international journal of energy and power engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e ne rg y an d p ow er e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/energy-consumption-and-economic-growth-in-south-asian-countries:-a-co-integrated-panel-analysis/ http://scholar.waset.org/ - / economic growth and hence, an increase in energy consumption tend to decrease economic growth. the coefficient of labor for whole region is also negative that indicate a negative effect of labor on gdp per capita. it may be due to brain-drain, uneducated, unskilled and low productivity of labor force. moreover results show that labor tends to decrease gdp per capita more than ec per capita. although this may be due to the fact that in developing countries, labor tends to be abundant and relatively cheaper. these results are similar with the findings of sari and soytas [ ]. capital plays a significant and positive role in gdp per capita that one percent increase in capital rise gdp per capita by . percent. it is consistent with theory that more capital accumulation ensures the economic growth. d. granger causality test results the short-run and long-run panel granger causality results from estimating panel based error correction model set out in ( ), ( ), ( ) and ( ) are reported in table: v. the optimal lag length is obtained ( ) by using schwartz information criteria (sic). table v panel granger causality results source of causation (independent variables) short- run long-run Δin gdp Δln ec Δin k Δln l ecm t- dependent variable Χ -statistics (p-value) coefficient (t-ratio) Δln gdp --- . ( . ) . ( . ) . ( . ) - . (- . *) Δln ec . ( . )** --- . ( . ) . ( . ) - . (- . *) Δln k . ( . ) . ( . ) --- . ( . )** . ( . *) Δln l . ( . ) . ( . ) . ( . ) --- . ( . ) notes: wald chi-square tests reported with respect to short-run changes while error term coefficient as long-run changes. parentheses values are the probability of rejection of granger non-causality. asterisks * and ** indicate statistically significant at % and % level respectively. results suggest that gdp per capita is causing ec per capita through error correction term but not the vice versa. this implies that there is significant unidirectional causation from gdp per capita to ec per capita in the short-run. moreover, there is existence of unidirectional causality from labor to capital, while among other variables no statistically significant causal relationship is found. in long-run, for gdp per capita equation, the estimated coefficient on error correction term is negative and statistically significant. it shows that short-term adjustments to equilibrium are driven by adjustment back to long-run equilibrium through error correction term. it takes years (calculated as the inverse of the absolute value of coefficient on the error correction term). for ec per capita equation, the estimated coefficient on error correction term is negative and statistically significant indicating that per capita energy consumption is responsive to adjustments back to equilibrium. it specifies long-run feedback between gdp per capita and ec per capita. vii. summary and policy implications the objective of study is to investigate causal relationship between energy consumption and economic growth by applying a multivariate model in five south asian countries over period - . recently developed panel cointegration technique is applied while long run relationship is estimated using fully-modified ordinary least square. the findings of the study have important policy implications. a unidirectional causality is found from gdp per capita to ec per capita in short-run. while, negative relation exists between the two in the long-run. thus, according to the results, south asian countries are benefited to adopt energy conservation policy to avoid the shortage of energy. otherwise energy crisis may seriously endanger the development of economies in the long-run. thus, it is quite important that along with the high energy consumption, the energy production raises to that extant to ensure sustained economic growth. to stay away from the energy crisis there should be some short-term and long-term planning, modified policies and enormous investment needed. avoid the import of crude oil at a massive cost of foreign reserve. south asian countries are rich in hydro resource of energy. therefore, there is need to build new dams, installation of wind power plant and tidal energy projects to explore the energy production. moreover, policy orientation needs a drastic modification to utilize endogenous resources. there must be short-term and long- term decisions regarding the state of natural resources of the economy. references [ ]. ikenberry, g.j. 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( ). cointegration and error correction: representation, estimation, and testing. econometrica, , – . [ ]. nelson, c.r., and plosser, c.i. ( ). trends and random walks in macroeconomic time series: some evidence and implications. journal of monetary economics, ( ), - . [ ]. lee, c.c. ( ). energy consumption and gdp in developing countries: a cointegrated panel analysis. energy economics, , – . [ ]. sadorsky, p. ( ). renewable energy consumption and income in emerging economies. energy policy, ( ), - . [ ]. sari, r., and soytas, u. ( ). the growth of income and energy consumption in six developing countries. energy policy, , - . world academy of science, engineering and technology international journal of energy and power engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e ne rg y an d p ow er e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/energy-consumption-and-economic-growth-in-south-asian-countries:-a-co-integrated-panel-analysis/ http://scholar.waset.org/ - / in sum, there is no doubt that the nsf changed considerably from the "pure" science image it had for its first years. in part this was undoubt- edly a consequence of the pressures of the times and of the perceptions of the nation's needs by the white house, omb, and the congress. but a large share of the responsibility was mc- elroy's. although dedicated to basic research, he also appreciated the strat- egy of promoting the practical ap- proach for solution of societal problems and, at the same time, securing funds for scientific research. it is apparent that the trend started then has con- tinued and even accelerated. how- ever one may view these changes, it remains evident that mcelroy per- ceived the approaching events and the needs they reflected and that he suc- cessfully capitalized on them for the benefit of the nation and of science. academic administration in february , mcelroy resigned from the nsf directorship to become chancellor of the university of cali- fornia, san diego. having spent his entire adult life in academia and being offered the opportunity to lead a young, high-quality institution of higher edu- cation, it is understandable that he found the opportunity irresistible. fur- thermore, as he himself said, acceptance of this job took him "from the hectic environment" (of washington politics), which he had not sought, back to an academic environment that was more compatible with his long-standing inter- ests. in his years at ucsd he has worked to balance the sciences and humanities, is overseeing an $ million construction program, and has guided the establishment of a fourth college, a percent expansion of the medical school, and the creation of several new academic departments. he has con- tinued to strengthen the ties of the university to the san diego community by establishing a community board of overseers, personally participating in many community civic activities, and fostering joint programs between the university and local corporations. he lives on the la jolla cliffs overlooking the pacific ocean with his second wife, the former marlene anderegg, who is also a biochemist, and their young son eric. to those who know him, bill (rarely mac) mcelroy is a vigorous, direct realist who knows and understands sci- ence and scientists and has definite ideas about their expanding potential societal roles. he is by nature an optimist, en- dowed with an agile mind, a quick sense of humor, and an infectious laugh. he retains the friendly informality of his native texas and is impatient with protocol and stuffiness. inherently com- petitive, he likes nothing better than a hot poker session, a tennis match, or a round of golf. although he no longer plays football, he is an ardent fan and retains a figure not too much changed from that of the stanford end of almost years ago. a verbal, pragmatic, driv- ing activist, restive with small detail, he has learned the ways of politics and is equally at ease with senators and un- dergraduate students. impatient with immobility, his quick and facile mind is capable of improvisation when that be- comes necessary and, when all else fails, he is inclined to revert to the old foot- ball dictum-when in doubt, charge through the center of the line. it is predictable that during the tenure of office of this likable, brilliant, and ac- tive man, aaas will not sit still. in , john wesley powell, ex- plorer, geologist, and ethnologist, was the retiring president of the american association for the advancement of science. major powell was the founder of the u.s. geological survey and the bureau of american ethnology; he was an enthusiastic advocate of the creation of a federal department of science. in his monograph on the lands west of the th meridian he was the first to show that a shortage of water the author is director of the center for popu- lation studies, harvard university, cambridge, massachusetts . this article is the text of his retiring presidential address delivered at the aaas meeting in new york city on january . would limit the development of the west. one might have expected him to use this presidential platform to pre- sent his views on some broad issues of science and society, but the traditions were different in those days. his presi- dential address consisted of a disserta- tion on "evolution of music from dance to symphony." it was only in the 's that retiring aaas presi- dents began to talk about broader is- sues, usually in terms of science as a great human enterprise and the duty of our association to defend it and spread its benefits among mankind. recognition of the social responsi- bility of scientists and technologists for the uses of their discoveries came after world war ii when the terrifying threats posed by nuclear and thermo- nuclear weapons became clear to all. but science and technology were still thought of as essentially neutral. their work could be used for good or ill, depending on the decisions made by other sectors of society. scientists could try to influence these decisions, but, in their capacity as scientists mainly on technical grounds. scientists and politicians should maintain an arm's length relationship with each other. the necessity for cooperation today this comfortable arm's length relationship will no longer do. the threats to civilization are too real and too immanent for anything other than the closest kind of cooperation among politicians and scientists in the search for ways out of our present dilemmas, in increasing public understanding of the issues involved, and in mobilizing the confidence and will of the people. science, vol. the scientist and the politician roger revelle o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ many events have converged to cre- ate our present precarious situation. among its outward signs are environ- mental decay; the depletion of re- sources; the rise of ever more per- vasive, ever more unresponsive, bu- reaucracies, both corporate and governmental; the economic contra- dictions of capitalism, as they manifest themselves in double-digit inflation, combined with economic stagnation or decline; the tragic gap between the rich and the poor countries with the resulting threats of rapid population growth, starvation, and social collapse; above all the malignant insanity of the arms race, and the strategy of mutual terror. but the real crisis of the west may exist within ourselves-in a fail- ure of nerve, a loss of self-confidence and a sense of pupose, a widening dis- illusionment with technology, and with economic growth based on technology -in short, a loss of faith in the inevi- tability or even the possibility of hu- man progress, the great idea that has powered our civilization for years. when i speak about science it must be understood that i am talking about both science and technology, for in our times they cannot be separated. this was not always true. the most important physical inventions in hu- man history-fire, fermentation, farm- ing, and the working of metals-all occurred before the natural sciences were born. likewise, the most impor- tant social inventions-birth control and cities-were made without benefit of the social sciences. but ever since some people began to realize they could learn about nature through the combination of theory and experiment which we now call science, the possi- bilities of applying this knowledge have been in the forefront of western thought. francis bacon said that we seek knowledge of nature to extend our dominion over things. three hundred and fifty years earlier, roger bacon had written, "machines may be made by which the largest ships, with only one man steering them, will be moved faster than if they were filled with rowers. wagons may be built which will move with incredible speed and without the aid of beasts. flying ma- chines can be constructed in which a man may beat the air with wings like a bird." and descartes said, "we can have useful knowledge by which, cog- nizant of the forces and actions of fire, water, air, the stars, the heavens, and all the other bodies that surround us, march knowing them as distinctly as we know the various crafts of the artisans, we may be able to apply them in the same fashion to every use to which they're suited, and thus make ourselves masters and possessors of nature." today, science and technology might be described as having a kind of incestuous relationship because tech- nology is both the mother and the daughter of science. most modern technological developments, including jet airplanes, computers, contraceptive pills, and hybrid corn, not to mention such mixed blessings as the control of nuclear energy, could not have oc- curred without the knowledge and understanding gained by science. and scientific discovery depends more and more on our ability to supplement our eyes and ears with complex instru- ments based on new technologies. some of the difficulties in discussing the need for coopera- tion between scientists and politicians, we must start by being aware of the difficulties. first, scientists and politi- cians have little mutual empathy. the personalities, methods, motivations, roles, and orientation of scientists and politicians are each foreign to the other. the politician is publicly ego- tistical, gregarious, garrulous, and has a strong gambling instinct. the scien- tist, at least in his own image, is pub- licly modest, introverted, relatively in- articulate, and seeks certainty rather than risk. in the past, the best science has been conducted within a narrow discipline, whereas the politician's methods are multidisciplinary in a way those of scientists can never be; they include the ancient arts of rhetoric and myth-making, appealing to the emo- tional and the irrational in other men as well as to their calculating self- interest. the scientist is motivated by the need to explain, predict, and con- trol phenomenache politician is moti- vated by a desire for power. or to make the contrast more exact, scien- tists and technologists seek power over nature; the politician seeks power over men. the scientist's role in society is to gain knowledge and understanding; the politician's is to decide and to act. indeed, in our democracy he alone has the obligation, as the people's elected representative, to make deci- sions as to what society shall do and to take responsibility for those deci- sions. in his search for truth, the scien- tist is oriented toward the future; the politician's orientation is usually here and now. he desires quick visible pay- offs for which he often seems willing to mortgage the future. for the poli- tician in a democratic society, infinity is the election after the next one. many barriers must be overcome before an effective working relation- ship can be established between politi- cians and scientists. ) most politicians are lawyers, and lawyers feel most at ease in adversary proceedings in which conflicting view- points and evidence are presented as a basis for decision. scientists generally shun such proceedings, preferring to work in committees or otherwise co- operatively, to examine facts and hy- potheses in order to find agreement or to clarify disagreements. ) scientists like to categorize them- selves in professional disciplines or subdisciplines. politicians and lawyers traditionally resist classification and tend to think of themselves as general- ists rather than specialists. ) politicians and lawyers are inter- ested in the particular rather than the general. they do not seek universal truths or broad generalizations, but are content with determining as best they can the facts that bear on a par- ticular situation. scientists are much more interested in regularities that underlie or explain an entire class of phenomena. ) politicians and lawyers need the best possible answers as soon as possi- ble. they are not interested in the scientist's search for certainty and his patient testing of hypotheses. they want to know and use the present state of the art, and in this respect they are more closely akin to engineers than scientists. ) technological advances all too often outpace political institutions. in his speech at the centennial celebra- tion of the national academy of sci- ences, president kennedy said, "when- ever you scientists invent a new technology, we politicians have to make a new political invention to deal with it." ) with regard to the social sciences, politicians tend to believe, with some justification, that they know as much or more about human behavior from a practical point of view as the psychol- ogist or the sociologist. they are un- sympathetic with the tentative nature of the social sciences and the wide o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ divergences of opinion among social scientists concerning the existence and character of regularities or laws of human and societal behavior. more- over, like other shamans, they do not like to have their secrets exposed. ) the main task of the politician is to mediate among competing social pressures to arrive at compromises that are most acceptable or least un- acceptable to most people. the scien- tist tends to take an uncompromising position which reflects the truth as it is known at a particular point in time. on advice-giving how can the politician and the scientist work more closely together? one way is to give each other advice. scientists have long accepted the idea that they should advise politicians, but they are liable to react with alarm and incredulity when it is suggested that politicians should advise them. the fact is, of course, that nowadays poli- ticians advise scientists in the most forcible and direct possible way-by granting or withholding support for research and development. i would ar- gue only that this process of mutual advice-giving should contain a better feedback mechanism. the scientist should advise the politician concern- ing the advice in the form of financial support that the politician gives the scientist. and similarly, the politician should advise the scientist concerning the kinds of scientific and technical ad- vice and the conditions under which it is given that will be most useful to him. limitations of scientific advice. when scientists advise politicians both groups need to recognize the limitations of the process. most scientific questions of interest to politicians contain a nonscientific, and often what alvin weinberg has called a "transcientific element." this is in part because the politician needs answers under time and action con- straints that are incompatible with sci- entific certainty, and in part, as victor weisskopf has pointed out, because a complete description of a phenomenon in scientific terms may not contain the elements of the phenomenon that hu- man beings consider most relevant. political decisions in such situations must be based on judgments that are outside the realm of science. tran- scientific questions that go beyond scientific certainty necessarily involve large areas of judgment in which indi- vidual scientists disagree. this disagree- ment is hard for the politician to deal with because he has difficulty in recog- nizing what, in the scientist's advice, represents scientific certainty and what are elements of judgment, estimation, and uncertainty. in other situations, the politician may accept the scientist's word that there is not enough information for scientific certainty without recognizing that nevertheless there is enough for political action. the scientist can help the politician evaluate the costs of making different kinds of mistakes, but insofar as these costs depend on value judgments, the scientist can give no more help than any other citizen. it is often stated that scientists and technologists can give useful advice to politicians about the character and time scale of future technological de- velopments, but this is true only to the extent that the basic scientific discov- eries or technical inventions have al- ready been made. otherwise, the scientist can only limit himself to pre- dictions that physical and biological laws will not be violated. by pointing out to the politician the intractable nature of many scientific and technical problems, he can help the politician suppress his natural tendency to solve these problems by political action. he can help him to avoid legislating a cure for cancer. the same difficulty exists, a fortiori, in forecasting the technical develop- ments that society will want or should want in the future. so-called normative technological forecasts depend on to- day's values and ideologies, which in a world of change may change at least as rapidly as technology itself. norma- tive technological forecasts are likely to be useful only if they are self- fulfilling prophecies. the scientist can advise the politi- cian on how to cure human ills, but not on how to produce human happi- ness. he must resist the tendency of the politician and the public to look upon him as a member of a remote omniscient priesthood even though public faith in science and scientists may be essential for the health of both science and society. two kinds of scientific advice. politicians need and can utilize scien- tific and technical advice given in several different ways. these can be conveniently classified as inside and outside, or, if youi will, in-house and out-house. the scientific adviser who is inside the system must be completely inside it. he must accept the politi- cian's rules of accountability and re- sponsibility, which always mean dis- cretion and loyalty and often anonym- ity. in other words, he should be a professional rather than an amateur. if he differs with his boss, he should re- sign, but not go public. scientific and technical advice from outside the political system is also use- ful especially if it serves to educate the public as well as politicians. it may be given by supposedly impartial commit- tees formed by academies and scientific associations or even by scientific and technical pressure groups. scientists can often give the most effective advice by "taking their case to the people." does the president need a science adviser? it is clear from what i have been saying that the presence within the executive office of the president of a group of full-time knowledgeable specialists, containing a mix of social and natural scientists from different disciplines, is essential to maintain the long-range effectiveness of science and technology in the united states, to develop broad strategies for science policy as well as ad hoc solutions for immediate issues, and to resolve con- flicting claims on scientific and techni- cal resources. whether advice from these technical experts should be presented directly to the president or should be filtered through a group of generalists in the white house will depend on the presi- dent's own needs and style. some presidents will want completed staff work in which scientific and technical factors are weighed against economic, political, and social ones in the alterna- tives presented to them for decision. others will prefer to judge for them- selves among the clash of opinions and to formulate their own options. political directions for science and technology the giving and receiving of advice is only one aspect of the need for new relationships between technology and politics. dean harvey brooks of harvard university recently gave a speech in which he asked the rhetorical question, "are scientists obsolete?" he immediately answered in the negative by describing major problem areas for future research and development. science, vol. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ most of these problems have arisen in part from the legislative or adminis- trative actions of politicians or will depend for their solution on coopera- tion among politicians, scientists, and technologists; for example, energy sup- ply and conservation; pollution control; technology assessment, that is, the side effects and secondary effects of new technologies; efficient, humane, and cost-effective health services; world food supplies and nutrition; the com- munications revolution as it will be affected by the breakdown of the tradi- tional monopoly of communications by common carriers; problems of increas- ing the productivity of the public sec- tor, particularly at state and municipal levels, and the productivity of the ser- vice industries in general; and the at- tempt to regain a comparative advan- tage for the united states in interna- tional trade, particularly in capital goods technology. to these i would add the stopping and reversal of the arms race, the highly inequitable dis- tribution of income in the world's poor countries, which probably lies at the root of population problems, and the social and economic transforma- tions being brought about by multi- national corporations, which may no longer be responsive to the traditional economic laws of supply and demand. beside their political nature, these problems have three common charac- teristics. (i) they involve the study of complex systems-the ecology of the natural world and of human societies, and systems of information, communi- cation, transportation, and control- that cannot be studied by the conven- tional reductionist methods of the natural sciences but demand instead a synthetic approach. (ii) they require intimate collaboration between social and natural scientists-consider, for example, the relationships between population distribution and the impact of environmental changes, and com- munal responses to risks created by environmental hazards. (iii) the re- sponsibility for solutions must be broadly shared among the people who will be affected. to exercise this re- sponsibility the public needs much more understanding of the issues, in- cluding the technical and scientific aspects. one of the major tasks of all concerned must be to increase public understanding of the potentialities and limitations of science and technology and the socioeconomic changes they both create and require. march two case studies to understand the difficulties of joining scientific knowledge with poli- tical action, let us take two case studies: our national failure to antici- pate the energy crisis and the slow progress of the "green revolution" in india. the energy crisis. although scien- tists concerned with natural resources knew and publicly stated for many years that the potential oil reserves in the united states are limited, and at least an order of magnitude smaller than our coal reserves, the energy crisis in the special form it has taken during the last years was not and could not have been predicted from geological considerations, because, in its immediate aspects, it is economic and political. nor would it have oc- curred to traditional economists that the arab countries and the other oil producers could organize an effective cartel. the actual costs of oil produc- tion in the middle east, both tangible and intangible, are about ¢ a barrel, a fiftieth of the present price, and the production potential is so much greater than world demand that the principal worry of the international oil com- panies before was the possibility of a break in prices due to oversupply. development of our own energy re- sources and a reduction of our profli- gate use of energy seemed to conflict with other social and economic goals, although from a long-range point of view this conflict was more apparent than real. in the short range, however, the new awareness of the environmen- tal damage caused by energy produc- tion, transportation, and use delayed construction of the alaska pipeline, virtually prevented the burning of high-sulfur coal and oil, inhibited ex- ploration and production of off-shore oil, and mandated energy-consuming antipollution measures. the national fixation on economic growth and the political pressures of vested interests determined government pricing and import policies which exacerbated the crisis of supply and prevented the adoption of energy conservation pro- grams. high interest rates and a short- age of capital, together with the oppo- sition of environmentalists, slowed the construction of nuclear reactors which could have taken some of the load off fossil fuels. the automobile manufac- turers stubbornly clung to making monstrous gas guzzlers because of their high profit margins rather than smaller cars that would economize on fuel. there were sharp disagreements among scientists and technologists on the size of u.s. reserves of petroleum, natural gas, and uranium and on the feasibility and timing of new energy sources. since some petroleum geologists have been predicting that our oil reserves were about to run out. these cries of wolf, in the face of in- creased oil supplies that resulted from new technologies for petroleum ex- ploration and recovery, lulled the pub- lic and the politicians into complac- ency. optimistic estimates of uranium resources by the atomic energy commission led to a weak program of research and development for breeder reactors. scientists and engineers dif- fered widely on the likely time scales or even the feasibility of development of thermonuclear fusion and other new energy sources. political action was inhibited by public disinterest. the average ameri- can, like his political representatives, has a high discount rate concerning the future. public opinion about long-range problems rarely crystallizes into a sense of urgency. the newspapers, popular magazines, and television reflect this lack of interest by giving little cover- age, particularly when the problems concern such hard-to-understand sub- jects as energy and fossil fuels which are full of numbers. scientists and en- gineers have contributed to the lack of public interest by cultivating, or at least not abjuring, the public's faith that science and technology will always come up with a miracle in time to avert a problem. john sawhill, for- merly the federal energy adminis- trator, said in a recent interview, "we can't move too fast on science and technology. the president can't intro- duce a program until the people are ready to support it, and the people won't be ready until they are in a crisis situation. once we are in a crisis we can shap a crash program to deal with it. i believe in the efficacy of crash programs. it's only when you marshall all your talents and resources on a crash basis that you get good hard results." in the light of the record in the energy crisis, this viewpoint can be most charitably described as trying to produce a baby in month by putting nine men on the job. finally, there were structural diffi- culties in the federal government and the energy industry that grossly re- o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ tarded effective federal action. more than a dozen federal agencies were charged with regulation of the energy industry or with energy research and development. the economic structure of the industry itself, as a partially regulated free enterprise, makes gov- ernment intervention difficult and a cause for resentment. the industry raises formidable obstacles to govern- ment action and its structure makes it hard to predict the effects of federal intervention. we can't go home again. the energy crisis will not go away. indeed, it is likely to persist for the rest of our lives and perhaps that of our children. it could be the immediate cause of the collapse of western civilization as we know it. a considerable degree of en- ergy conservation is both possible and desirable, but it is mindless to suppose that we can reverse our dependence on nonhuman energy. we have gone too far in raising life expectancy, and hence the numbers of people, and in lifting the burden of physical labor from the backs of farmers and city dwellers. without mechanical energy our cities would be uninhabitable and many people would starve. an old saying has it that "slavery will persist until the loom weaves itself." all ancient civilizations, no matter how enlightened or creative, rested on some form of slavery, be- cause human and animal muscle power was the principal energy available for mechanical work. it is not because we are enlightened that we have abolished slavery but because we have discovered a cheaper source of energy. a man can produce in a day about a kilowatt-hour of mechanical work; to keep him work- ing on the meagerest of diets costs ¢. even at present oil prices, a kilowatt- hour of electrical power, or the equiva- lent in gasoline, costs only about ¢. by its discovery of less expensive en- ergy than human muscles, western civilization, unlike all others, has been able to make men free. put in other terms, once a society has climbed onto the treadmill of tech- nology, it can never get off again. no solution of the energy problem is pos- sible without far-reaching technologi- cal advances in both the production and the conservation of energy. but the lesson up to now is that such tech- nological advances will not occur in time, or may not take place at all, without enlightened, far-seeing political action, courageous political leadership, and clear public understanding of the issues and possibilities. our future wel- fare and perhaps our survival will de- pend on the closest kind of coopera- tion between politicians, technologists, and natural and social scientists. this, in turn, will depend both on an en- lightened public support and on the politician's sensitivity in recognizing what the people would want if they had a chance to want it, that is, the choices they would make if those choices were actually available. social scientists have a special role to play in defining and appraising the possible range of public choices. how to stop a revolution. why has the "green revolution" progressed so slowly in india? when the new high- yielding varieties of wheat were first introduced in the middle 's they caught hold with great rapidity. from a few demonstration farms the new varieties spread to millions of acres within years and the results were spectacular. india's wheat harvest doubled from to . in , india produced a large surplus of food grains, more than enough to feed the millions of refugees who poured over the borders from what is now bangla- desh. but from onward, food production has hardly increased at all, nor has the area planted to high-yield- ing varieties of wheat and rice. a drought in and poor weather conditions over large regions during the monsoon, combined with the worldwide rise in petroleum and fer- tilizer prices, are partly responsible, but a major share of responsibility must be assigned to governmental ac- tions and inactions. farm prices of cereals have been kept low in order to placate the urban masses while fertil- izer prices have steadily risen. it takes two or three times as much wheat or rice to buy a pound of fertilizer in india as in japan and considerably more in india than in pakistan. to buy fertilizers the farmers must have credit on reasonable terms and this has not been available. most small farmers are still in the grip of the traditional village moneylenders. many of these farmers are sharecropping tenants with little or no security of tenure; they do not have much to gain from planting new high-yielding seeds which require expensive inputs of fertilizer, irrigation water, and plant protection. land reform has been vir- tually nonexistent even though man' larger landowners have failed to in- tensify their farming practices. the state governments, which are mainly responsible for agricultural develop- ment, have been dominated by the richer farmers and they have neglected the interest of the small farmers and the incentives they need to increase their production. insufficient resources have been al- located to the agricultural sector, with the result that development of irriga- tion has been very slow even though in most regions irrigation is required for the new varieties. because of the great uncertainties in rainfall, farmers are reluctant to invest in fertilizers in unirrigated areas, and consequently the growth in the use of fertilizers has lagged far behind the expectations of the planning commission. extension services, which could provide instruc- tion to the farmers on proper tech- niques of fertilizer application, and soil testing services, which could indicate the required mix of fertilizer and needed soil amendments, are com- pletely inadequate, and consequently crop responses to fertilizers are much lower than they should be. at the same time there have been short falls in fer- tilizer supply because of the slow rate of development of domestic fertilizer production. because the central and state gov- ernments have neglected the develop- ment of seed multiplication farms, the seeds of the new varieties have been in short supply. many of the seeds, sup- posedly of high-yielding varieties, pur- chased by the farmers are adulterated with seeds of the older varieties or even with weed seeds. the agricultural re- search establishment has been suffi- ciently remote from the realities of farming that new rice varieties adapted to the special situations in many re- gions of the vast country have not been developed. the future of the green revolution. an enormous increase in agricultural productivity based on new agricultural technology is still possible in india, but it can occur only if social and eco- nomic reforms are carried through by vigorous government action and if the government can find the will to divert greater resources from other sectors to agriculture. here we find another clear- cut example of the issues i have tried to stress: biological and physical sci- ence and technology can be usefully applied on a large scale only in the context of changes in social and eco- nomic institutions, illuminated by the insights of the social sciences, and car- ried out by politicians who are able to mobilize an effective public support. science, vol. o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ a national policy for science and technology what can we do to improve the effectiveness of cooperation between politicians and scientists and technolo- gists? one step would be the formula- tion and adoption by congress of a national policy for science and tech- nology as a guide to legislative and executive action, just as years ago the congress adopted a national eco- nomic policy. such a policy would have three clearly expressed goals: (i) to maintain the health and effectiveness of scientific research and technologi- cal development in the united states; (ii) to assure the maximum usefulness of scientific and technological advances in serving the people's interests; and (iii) to provide for evaluation and assessment of unforeseen or undesir- able effects of new technology and advances in applied science. dealing with long-range problems. the policy would recognize that gov- ernment support is essential to deal with long-range problems at an ade- quate level of effort. it would empha- size the development of ways to recog- nize and define problems that will arise in the future and to improve the gov- ernment's capacity to deal with them. only the federal government can main- tain a sufficiently low "social discount rate" to give a significant "present value" to problems that may take decades to solve. maintaining the health of the scien- tific enterprise. the national policy for science and technology should ensure a continuing flow of highly educated, dedicated, and promising young peo- ple into the nation's scientific and tech- nical effort. it should aim at the widest possible base for identifying and edu- cating these young people without re- gard to sex, ethnic origin, geographical regions, or socioeconomic status. at the same time, the policy should state the national intent to maintain a full range of research and development facilities which will ensure that the nation's sci- entific and technological community can perform at high effectiveness. because experience shows that sci- ence and technology form a seamless web, a national policy established by congress should state the nation's in- tent to support both pure and applied science, both free research and mission- oriented research and development, both "big science" requiring expensive installations, and "little science" requir- ing modest equipment, and science in all its disciplines. science and technol- ogy depend on a variety of institutions -universities, government laboratories, industry, and nonprofit institutions- and the national policy should en- compass all of them. scientific freedom and responsibility. a national policy for science and technology should provide for a broader public understanding of the nature of the scientific enterprise and the possibilities and limitations of tech- nological development. to further such understanding, scientists and engineers should be guaranteed the freedom to express their ideas about the probable consequences for society of their dis- coveries, and their sense of responsibil- ity for the potential social effects of their research should be encouraged. uses, priorities, and impacts. a na- tional policy for science and technol- ogy should aim to ensure that new or prospective technological developments are taken fully into account in the budgeting and programs of federal agencies. at the same time, it should encompass mechanisms to ensure that priorities for scientific and technologi- cal research and development set by different federal agencies make sense in terms of national goals, and are realistic in terms of feasibility, scientific and technical manpower requirements, timing of expected results, and avail- able funds. it should recognize govern- mental responsibility for evaluating the probable impact of new products on human health and welfare and the nat- ural environment. science, technology, and foreign pol- icy. finally, one aim of a national policy for science and technology should be that the best scientific and technical information is fully utilized in making and implementing the na- tion's foreign policy, and that our unique scientific and technical capa- bilities are both an instrument and an object of foreign policy. attention should be paid to means of increasing imports and exports of technology and to the "balance of trade" in technical exchange with other countries. inter- national cooperation and cost-sharing in scientific research and technical develop- ment should be encouraged and tech- nology transfer as a major element of assistance programs for less-developed countries should be facilitated. interna- tional constraints on oceanic, atmospher- ic, and space research should be avoided. what room does this talk of the applications of science and technology leave for the strength and integrity of science itself? these do not lie in the impressive products or the powerful instruments of science but in the minds of the scientists and the system of dis- course they have developed to seek a more perfect understanding. the strength and integrity of science can be protected by its uses in education, its international character, and its uniquely human quality. scientific research in its broadest sense is the solving of problems to which no one knows the answers. this is the essence of higher education and it is why teaching and research should be inseparable. scientific education must include the learning of facts and unifying principles, but it is far more important that students learn how to discover, recognize, and use the truth. it is a truism to say that neither the work nor the results of science can be confined within national boundaries. many people in many nations can con- tribute to it. all human beings every- where may benefit or be harmed by its application. science unifies men. the search for an ever-growing but never complete understanding is that uniquely human activity which dis- tinguishes human beings from all other living things. indeed, i would claim that man is the first step in the evolu- tion of a new form of matter-new because it can understand the world and itself. we look at the stars with awe and wonder. the stars do not look at us at all because they have no eyes to see with and no minds to be struck with wonder. understanding can be sought for and obtained in different ways. but one of the most powerful, because it builds on the past and combines the efforts of many individuals, is the method of sci- ence-that method of free inquiry, theoretical construction and empirical testing which is the special heritage of western civilization. science is more than the handmaiden of technology or the abstract possession of a few. it does more than allay men's fears and inform their hopes. it helps to give them their true dignity as men. aris- totle said it in simple words more than two millennia ago: the search for truth is in one way hard and another easy. for it is evident that no one can master it fully, nor miss it wholly. but each adds a little to our knowledge of nature, and from all the facts assembled there arises a certain grandeur. march o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ the scientist and the politician roger revelle doi: . /science. . . ( ), - . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the trademark of aaas. is a registeredscienceadvancement of science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for thescience of science. no claim to original u.s. government works. copyright © the authors, some rights reserved; exclusive licensee american association for the advancement o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ combustion,pyrolysis, pyrolytic oil, wood residues, bioenergy energy and power , ( ): - doi: . /j.ep. . combustion properties of some tropical wood species and their pyrolytic products characterization adegoke o. a. ,*, fuwape j. a. , fabiyi j. s. department of wood and paper technology, federal college of forestry, ibadan, nigeria department of forestry and wood technology, federal university of technology, akure, nigeria abstract this paper evaluates the combustion properties of fuelwood and pyrolytic products from three selected sawmill wood residues - gmelina arborea, terminalia superba and triplochiton scleroxylon. pyrolysis experiments were performed at , and °c. the percentage oil, ph, viscosities were considered. the highest yield of oil yield was at °c ( . %) for triplochiton scleroxylon out of the three sawmill wood residues. the analysis of variance conducted on pyrolytic oil produced at , and °c for the g. arborea, and t. scleroxylon showed no significant difference but there were significant differences in the ph and viscosity of the pyrolytic liquid produced from selected wood species at the same conversion temperatures. the result showed the proximate analysis of the selected wood residues with the ash content ( . , . , and . %); fixed carbon ( . , . and . %); volatile ( . , . and . %) and heating value of . , . and . kj/kg for gmelina arborea, terminalia superba and triplochiton scleroxylon respectively. proximate analysis results showed that the selected wood residues have good potential for domestic cooking and the characterized pyrolytic oil produced for biofuel production, most importantly for bioenergy sustainable system. keywords combustion, pyrolysis, pyrolytic oil, wood residues, bioenergy . introduction wood which is the dominant biomass used in energy generation is a lignocellulosic biomass that is a clean biomass. the products from wood comprises of slab, twigs, leaves off-cut, branches, planks, boards, sawdust, among others. wood has been extensively studied because of its use as a construction material [ , ] and as fuel source [ ]. combustion properties of wood are also important because of safety issues since it is one of the more commonly available flammable materials. based on its widely usage, wood has been the major source of renewable energy for developing countries the renewable energy source can play a major role for sustainable development. the urgent need in most developing countries like nigeria is the migration to sustainable energy system and one of the energy sources is wood waste or sawmill residues which are regarded as waste in many sawmills industries. the availability of fossil fuels is limited, considering the fact that the demand for energy from fossil fuel is growing at high rate due to industrial development and is a major contributing factor to energy crisis. the energy crisis and fuel tension made biomass (forest residues) fast pyrolysis * corresponding author: aolaoluwa.adegoke@gmail.com (adegoke o. a.) published online at http://journal.sapub.org/ep copyright © scientific & academic publishing. all rights reserved liquefaction a more important area of research and development [ - ]. in particular, the most advanced biomass pyrolysis processes, oriented to the production of an organic liquid fuel (referred to as bio-oil, bio-fuel-oil or bio-crude-oil, pyrolytic oil), appear to be very interesting for several possible energy application that can be envisaged for this fuel. the combustion property of selected tropical wood species was considered investigated and its pyrolytic oil characterization. this study became important in view of the recent interest in the use of wood biomass, sawdust in particular as waste. however, the study seeks to find a path way of utilizing sawdust during the conversion of the wood in sawmill as domestic wood fuel and bio-oil production thus, minimizing waste and reducing global warming through drastic burning [ ]. . materials and methods . . samples preparation gmelina (gmelina arborea), afara (terminalia superba) and obeche (triplochiton scleroxylon) wood residues (sawdust) collected from a local sawmill located at akure, ondo state, nigeria were used as feedstock for the production of pyrolysis oil. the sawdust was air-dried to eliminate excess free water and prevent degradation by fungi. the samples were later oven dried at a temperature of energy and power , ( ): - ± °c for until constant weight was achieved. nine replicates of g specimens were weighed per wood species for pyrolysis experiment. . . pyrolysis experiment each wood species was put inside the pyrolytic chamber and then subjected to a predetermined temperature. three different temperature regimes were considered which include , and °c while three replicates per wood species at each temperature were considered. the gases that evolved were distilled in the condenser to form pyrolytic oil which was retained in a conical flask. the oil retained was condensed at °c using a reflux system. ( ) feedstock, ( ) pyrolytic chamber, ( ) furnace, ( ) chamber rod, ( ) condenser ( ) cold water inlet ( ) cold water outlet ( ) emitted gas ( ) conical flask ( ) pyrolytic oil and tar figure . schematic diagram of pyrolyser experimental set-up . . pyrolytic oil products characterization . . . physical properties pyrolytic oil the viscosity of the condensate was determined using ostwald viscometer at °c. the oil was released to flow through the capillary tube and the time for the upper bulb to be measured. the mathematical formula used to calculate the viscosity was expressed as written in equation . the ph of the pyrolytic oil was determined with the use of a ph meter with a calibrated electrode using buffer solutions of ph and . the density was determined by taking the weight of the oil using an electronic weighing balance and measuring the volume using a graduated cylinder. the formula for calculating the percentage oil yield and char are expressed in equations and , respectively [ , ]. the oil density and char yield were calculated using the formula expressed in equations and , respectively. ( ) oy is the oil yield (%), wo is the weight of oil and ws is the weight of wood sample. ( ) where, r is the radius of the viscometer, ρ is the density, g is the acceleration due gravity and vt = d/t (where vt = terminal velocity, d = distance and t = time. ( ) where, m is the mass of the pyrolytic oil obtained (g), v is the volume of pyrolytic oil obtained (cm ) ( ) where cy is the char yield, wc is the weight of char and ws is the weight of wood sample. . . . proximate analysis of the feedstocks the proximate analysis determined includes percentage volatile matter (pvm), fixed carbon (fc), ash content (ac) and heating value (hv). the pvm and ac were determined in accordance with the astm e - [ ] and astm e - [ ] respectively. for the pvm, g of the wood residue was placed in a crucible of known weight and oven dried to a constant weight after which it was heated in the furnace at temperature of °c for minutes. the pvm was then expressed as the percentage of loss in weight to the oven dried weight of the original sample. the percentage of ac followed the same procedure with volatile matter except that the sample was heated in furnace for h. the ash content obtained after cooling in a desiccator was expressed as percentage of the original sample. the percentage of fc was calculated as expressed in equation [ ]. the heating value was computed from the percentage fixed carbon and percentage volatile matter using gouthal formula (equation ). c = − (%v + % a) ( ) where, c is the percentage of fixed carbon, v is the percentage of volatile matter and a is the percentage of ash content. ( ) where, hv is the heating value (kj/kg), c is the percentage fixed carbon, and v is the percentage of volatile matter [ ]. . . data analysis the physical properties (percentage oil yield, char, volume, density, ph, and viscosity) of pyrolytic oil and proximate analysis of the wood residues (sawdust) obtained for the three different wood species were determined. analysis of variance (anova) was carried out on physical properties and proximate analysis while duncan multiple range test (dmtr) was used to evaluate the effect temperature and sawdust types on physical properties of the oil and proximate analysis. . results and discussion . . physical properties analysis the physical characteristics considered for pyrolytic oil of the various wood species include percentage oil yield, oy = wo ws viscosity = r (ρ)g x vt d = m v cy = wc ws hv = . ( . c + v) adegoke o. a. et al.: combustion properties of some tropical wood species and their pyrolytic products characterization volume, density, ph, viscosity at three pyrolytic temperatures of , and °c (table ). table . physical properties of pyrolytic oil and charcoal produced from three selected wood species’ residues at three different temperatures properties temp. (°c) wood species gmelina arborea terminalia superba triplochiton scleroxylon oil yield (%) . ± . a . ± . a . ± . a . ± . a . ± . b . ± . a . ± . b . ± . c . ± . b char (g) . ± . b . ± . c . ± . c . ± . c . ± . b . ± . b . ± . a . ± . b . ± . b volume (cm ) . ± . a . ± . a . ± . a . ± . a . ± . a . ± . b . ± . b . ± . b . ± . a density (g/cm ) . ± . a . ± . b . ± . a . ± . a . ± . b . ± . a . ± . a . ± . a . ± . a ph . ± . a . ± . a . ± . a . ± . b . ± . a . ± . b . ± . b . ± . a . ± . b viscosity @ °c cp . ± . b . ± . b . ± . b . ± . a . ± . a . ± . b . ± . a . ± . a . ± . a mean±standard deviation. values with the same alphabet in each column are not significantly different (p≤ . ) using duncan multiple range test the percentage oil yield increased significantly (p< . ) with increase in the pyrolytic temperature. this was due to tar produced during the pyrolysis process that is, addition of this tar increase the percentage oil yield along side with the volume. t. scleroxylon had the highest oil yield ( . %) at °c followed by t. superba at °c ( . %) while g. arborea had the lowest oil yield ( . %) at °c. the result of the high yield of pyrolytic oil obtained at °c agreed with [ ] on the fast pyrolysis of wood feedstocks from pterocarpus indicus, cunninghamia lanceolata, fraxinus mandshurica and rice straw. this present experimental study has showed that the pyrolytic oil at °c could give relatively high yield. from table , it is evidenced that there was no significant difference in the density of the pyrolytic oil produced at , and °c for the g. arborea, and t. scleroxylon. however, the density °c differed significantly to and °c for terminalia superba. pyrolytic oil density varies with temperature conversion and moisture content of the content of the feedstock [ ] and this was realized from the present study that the temperature regimes and types of feedstock affect the density of pyrolytic oil produced. the density values obtained in this study agreed with [ ] and [ ] who reported on fast pyrolysis of wood and microalgae and [ ] on physiochemical properties of bio-oil from other feedstock. the ph of the pyrolytic oil differs significantly between and °c for g. arborea and t. scleroxylon. it was observed that the ph at °c is higher than at °c for both wood species. for t. superba, the ph was not significantly different irrespective of the pyrolysis temperature. the report on other bio-oil or pyrolytic oil has shown that the ph of pyrolytic oil range between . and . [ ] which corroborate with this study. this implies that the pyrolytic oil is highly oxygenated and acidic [ ]. there is significant difference in the viscosity of the pyrolytic liquid produced from selected wood species at the same temperature of conversion. this implies that viscosity decreases as the temperature increases. pyrolytic viscosity reduces faster at higher temperature, though, more viscous than petroleum derived oil after a moderate preheating [ ]. the viscosity of bio-oil can vary over a wide range from - cp °c [ ]. . . proximate analysis the proximate analysis of the three selected wood species’ residues is presented in table . percentage ash content, fixed carbon and volatile matter ranged from . to . %, . to . % and . to . % for g. arborea, t. superba and t. scleroxylon, respectively. it was observed that there was no significant different in the percentage ash content, volatile matter among the selected wood species but differed significantly for percentage fixed carbon (p< . ). the heating value for the g. arborea, t. superba and t. scleroxylon was recorded as . , . , and . kj/kg, respectively. however, there was no significant different in heating value of three selected wood species. the proximate analysis of the selected wood species showed that they have good potential for domestic cooking and good combustion properties. table . proximate analysis and heating value of char produced from three selected sawmill wood residues proximate analysis sawmill wood residue gmelina arborea terminalia superba triplochiton scleroxylon ash content (%) . ± . a . ± . a . ± . a fixed carbon (%) . ± . a . ± . b . ± . a volatiles matter (%) . ± . a . ± . a . ± . a heat value (kj/kg) . ± . a . ± . a . ± . a mean±standard deviation. values with the same alphabet in each column are not significantly different (p≤ . ) using duncan multiple range test. energy and power , ( ): - . conclusions this study investigated the combustion property and pyrolysis experiment of sawdust of gmelina arborea terminalia superba and triplochiton scleroxylon at three different temperatures ( , and °c). the highest oil yield was at °c ( . %) for t. scleroxylon. the result obtained from this present study put forward that the pyrolytic oil from the pyrolysis of the sawdust is suitable as a feedstock for the production of alternative fuels. the proximate analysis of the selected wood species showed that they have good potential for domestic cooking. references [ ] wangaard, f. , wood: its structure and properties. materials research laboratory, the pennsylvania state university, university park, pennsylvania. [ ] freas, a. , wood: engineering design concepts. materials research laboratory, the pennsylvania state university, university park, pennsylvania. [ ] ragland, k., aerts, d. and baker, a. , properties of wood for combustion analysis. bioresource techn., ( ), - . [ ] bridgwater, a.v and peacocke, g.v.c. , fast pyrolysis processes for biomass. sustain renew energy rev : – . [ ] scott, d.s, piskorz, j and radlein, d. , liquid products from the continuous flash pyrolysis of biomass. ind eng chem process des dev : – . [ ] czernik, s.r, and bridgwater, a.v. , overview of applications of biomass fast pyrolysis oil. energy fuels ( ): – . [ ] u.s. doe , available at: http://www.energy.gov/ accessed august, . [ ] the pigsite.com , available at: http://www.thepigsite. com/articles/ /manure-to-energy-the-utah-project accessed march, . [ ] annual book of astm standards. . standard test method for volatile matter in analysis of particulate wood fuels. e - . [ ] annual book of astm standards. . standard test method for ash in biomass. e - . [ ] garcia, r., pizarro, c., lavin, a.v., bueno, j.l. , characterization of spanish biomass waste for energy use, bioresource technol. , - , doi: . /j.biortech. . . . [ ] bailey, r.t, and blankehorn, p.r . calorific and porosity development in carbonized wood. wood science ( ): - . [ ] luo, z.; wang, s.; liao, y.; zhou, j.; gu, y.; and cen, k. , research on biomass fast pyrolysis for liquids fuel. biomass bioenergy , - . [ ] mohammad, r.i., nurun, n., and islam, m.n. . the fuel properties of pyrolytic oils derived from carbonaceous solid wastes in bangladesh jurnal teknologi, (a): - . [ ] miao, x.; wu, q. and yang, c. . fast pyrolysis of mircoalgae to produce renewable fuels. j. anal. appl. pyrol., , - . [ ] miao, x.; wu, q. . high yield bio-oil production from fast pyrolysis by metabolic controlling of chlorella proto-theecoides. j. biotechnol., , - . [ ] garcia-perez, m.; chaala, a.; roy, c. . vacuum pyrolysis of sugarcane baggasse. j. anal. appl. pyrolysis , - . [ ] fuwape, j.a., fabiyi, j.s. and adegoke, o.a. , fourier transform-infrared analysis of pyrolytic oil from selected wood residues. journal of forests and forest products society of nigeria. ( ): - . [ ] diebold, j. and scahill, j. , production of primary pyrolysis oils in a vortex reactor. in: pyrolysis oils from biomass: producing, analyzing and upgrading. (eds. e.j. soltes, t.a. milne) acs, washington, dc, acs symposium series , pp - . 	 . introduction 	 . materials and methods 	 . results and discussion 	 . conclusions untitled- © nature publishing group nature vol. april obituary sir gerard thornton microbiologists, especially those who had the good fortune to work with him, will have heard wi-th sadness of the death of sir gerard thornton on february at his home in st. albans at the age of . he is survived by his widow, gerda, who is danish, and by his son peter who is keeper of woodwork and furniture at the victoria and albert museum. he will be remembered for his many original and important studies on so-il microbes, made in the course o-f a long career spent almost wholly at roth- amsted experimental station, harpen- den. he was educated at radley and at new college oxford and joined rothamsted shortly after the end of the great war where he had served as a pilot in the royal flying corps. in , soil microbiology was a very rudimentary science, and thorn- ton's early work was much concerned with the devising of techniques for iso- lating , identifying and counting various kinds of soil bacteria and in promoting parallel studies by others on soil fungi, protozoa and other groups. with his friend the late r. a. fisher he pioneered the application of statistics to the problems of enumerating bac- teria in soil. at this time he was also in contact with the great european soil microbiologists-be.jjerinck, winograd- sky, kluyver and later with waksman. he had a special interest in the micro- bial breakdown of aromatic disinfec- tants in soil, and made a collection of bacteria able to utilise cresols, phenols and naphthalene as sole ca!'bon sources and elucidated some aspects of their physiology. this work was later to be- come specially relevant to the dis- covery, which he shared with others, of the selective hormone herbicides (chlorinated phenoxyacids), first pub- lished in nature (iss, ; ). his greatest influence, however, was through his distinguished research on biological nitrogen fixation, especially by root-nodulated leguminous plants. his detailed investigation of their microbiology , structure and physiology ja,id the foundation for nearly all later work and led to practical applications in uk agriculture. his work estaiblished the 'bacteroid' as the nitrogen fixing site in the nodule and he described in detail the features of ineffective, non· fixing nodules. with his rothamsted colleagues he was the first to use sera- logical methods for identifying rhizobia and was associated with early work on bacteriophage and with studies on ecology of rhiwbia. thornton was also the first to investigate effects of com- petition between strains in the soil, a matter later shown to be important in the development of efficient 'inocu- lants' for leguminous crops. since his retirement in he continued to show the greatest interest in nitrogen fixation and in the striking advances made world-wide in its study during the last decade, stimulated by the inter- national biological programme and the energy crisis. thornton had wide interests in science and in the arts. he was especi- ally interested in archaeology and in palaeontology and had the distinction of discovering a new species of plesiosaur (rhomaleosaurus thorntonii) which can be seen at the british museum, natural history. thornton became head of the de- partment of soil microbiology in . he was elected to the fellowship of the royal society in , of which he was foreign secretary from - and a vice-president in - . he was actively involved in the organisa- tion of the society's tercentenary cele- brations and was knighted in . he served on the council of the royal sooiety and on many bodies concerned with microbiology and with agriculture. thornton was a quiet, modest man, invariably considerate and courteous with a charm of manner rarely seen today. his colleagues remember him with respect and affection. p. s. nutman d. e. wheeler dr d. e. wheeler who died on january , was a chemist who in twelve years as managing director of the wellcome foundation limited and a further three as a deputy chair- man was concerned particularly with the profitable translation, through de- velopment and production, of the fruits of scientific research into important drugs and vaccines. as president of the association of the british pharma- ceutical industry he was a leading figure during an era when regulations were being established in the wake of the thalidomide tragedy. his integrity, relied upon alike by those in industry, medicine and government, was a major s factor in the harmonious and successful negotiations. as first-ever chairman of the spastics society he brought together two organisations concerned with the welfare of spastics and presided over a massive expansion on the financial side, making possible the sponsorship of original research on a considerable scale. denis wheeler was born in bristol on september, , and graduated from bristol university where he specialised in physical chemistry and carried out research work which led to a ph.d. in . he was awarded a salters' fellow- ship to study industrial organisation and practice in the united states. part of the time was spent at princeton university where he studied advanced physical chemistry. in later years he was to become master of the salters' company and concerned with the con- tinuation of this type of scientific exchange. on his return to britain he joined the research department of imperial chemical industries (explosives) ltd where he eventually became technically responsible for all acid production throughout the ici organisation in great britain. in he was appointed research and development director of hardman and holden ltd, chemical manufacturers. he joined the board of directors of the wellcome foundation limited in january , was appointed assistant managing director later that year, joint managing director in , managing director in and a deputy chairman in . he retired from the board for health reasons in . he was awarded the cbe in . in his early years with the wellcome foundation, dr wheeler was con- cerned with the organisation of de- velopment as a specific function, ensuring that the discoveries of the research laboratories could be produced in the appropriate formulations and on a sufficient scale to be administered to large numbers of humans or animals throughout the world . whereas the re- search laboratories of wellcome had been largely independent of the com- mercial company, he was able to con- vince the scientists that their work could still retain its integrity and its impetus whilst being guided towards the discovery of essential medicines, the sale of which would provide the resources for further research. d. w. adamson 	d. e. wheeler industrial engineering journal june vol. x & issue no. june - performance of lighting system of a pharmaceutical industry piyush jain dr. s.c solanki dr. ravi nagaich pavan jain abstract lighting constitutes a main portion of energy consumption in commercial as well as in industrial sector. the energy auditing is the key of the consumption which stabilize the situation of energy crisis by providing the conservative measures. any organization so called bulk consumer of electrical energy gives emphasis to adopt suitable technology or scheme of energy conservation to minimize the unwanted power shutdown either incidentally or by load shedding. as the energy costs increases, possible efforts are to be done to minimize the energy consumption of lighting installations and efficient use of the energy consuming equipments . this follow three basic directions: new more efficient equipment (lamps, control gear, etc.), utilization of improved lighting design practices, replacing excess energy consuming equipments from energy efficient equipments, improvements in lighting control systems to avoid energy waste for unoccupied and daylight hours. in this paper an energy audit has been conducted in the pharmaceutical industry to estimate the energy consumption. in this energy audit, the cost analysis and pay back periods have been calculated by replacing the higher consumption lamps with energy efficient lightning also checking the feasibility of the different departments of the industry from energy point of view. the profit of implementing the energy efficiency measures in industry are considerable both in terms of energy savings and cost savings. keywords: energy audit, installed load efficacy ratio, energy efficient measures, payback period. . introduction lighting plays a very vital role in enabling people to carry out their tasks safely, efficiently and without discomfort, however electric lighting can account for around - % of your electricity bill. an energy efficient lighting system combines, low running and maintenance cost, with good effective lighting and can reduce the facility's lighting cost by up to a third. energy performance of various types of buildings - office, industrial, healthcare, educational and other buildings - is a widely discussed issue at different levels. the solution of energy performance of lighting systems of these buildings is also a part of these discussions. lighting is a large and rapidly growing source of energy demand and greenhouse gas emissions. in , grid-based electricity consumption for lighting was twh worldwide, which was about % of the total global electricity consumption. furthermore, each year billion litres of gasoline and diesel are used to operate vehicle lights. more than one-quarter of the population of the world uses liquid fuel (kerosene oil) to provide lighting (iea ). a more efficient use of the energy used for lighting would limit the rate of increase of electric power consumption, reduce the economic and social costs resulting from the construction of new generating capacity, and reduce the emissions of greenhouse gases and other pollutants into the environment. at the moment, important factors concerning lighting are energy efficiency, daylight use, individual control of light, quality of light, emissions during the life-cycle, and total costs. energy audit is a process of checking the way energy is used and identify areas where wastages can be minimized if not totally eradicate. energy audit consists of several tasks which can be carried out depending on the type of audit and the function of audited facility. it started with review the historical data of energy consumption which can be compiled from the electricity bills. these data is important in order to understand the patterns of energy used and their trend. after obtaining the information on energy consumption, the next step is to set up an energy audit program. therefore energy audit is essential part has to be carried out as it determines several energy saving techniques which can be opted within an organization to reduce electricity consumption. to achieve optimal energy efficiency in buildings, energy audit is able to reduce energy wastes and provides the cost benefit. the energy audit and energy conservation measures described in the research paper does not only provide a very different perspective to the wastage and energy crisis and energy security but also an implementation platform that addresses all aspects of managing several energy s o u r c e s . p r e s e n t c a s e s t u d y o f p a r s h pharmaceuticals ltd mainly deals with analyzing the lighting system in the industry, checking the lighting efficacy of the different areas of the industry by applying the concept of energy audit. . literature review before conducting the detailed energy audit of the case organization, a significant literature review was carried out to appreciate the field of research. this section systematizes reviews of literature which provides necessary information regarding energy auditing technique and its implementation. some important reported research studies related to energy conservation are mentioned below:- doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . issn: - issn: - issn: - industrial engineering journal june s.n. research paper author summary of the work a case study on energy conservation & audit for household applications kongara ajay this paper analyses the amount of wattage consumed by different devices and suggested necessary replacements and showed the net savings. energy audit of a industrial site : a case study matteo dongellini this paper presents the results of a preliminary energy audit carried out on large industrial buildings of a famous car manufacturing holding in italy energy conservation measures in a technical institutional building p. loganthurai in this paper it was proposed to implement energy conservation through energy efficiency and energy management electrical energy conservation in underground mines mr. ganapathi. d. moger in this paper, the various electrical equipments used in the opencast and underground coal mines are listed in the literature work, their specifications & operations are explained. potentials for reducing primary energy consumption through energy audit in the packaging paper factory nikola tanasic this paper provides measures to increase energy efficiency of the packaging paper production process together with the quantification of the potential savings in the primary energy consumption are also presented in the paper. optimizing the energy in an educational institution using energy audit technique arun govind m this paper provides the initial investment and the payback period calculations of each block in educational buildings with effective replacement. energy audit of a food industry kaur poonam, thakur ritula from the survey, it was found that, luminance was poor, in few areas. after implementing iler technique, illuminance was under permissible limit. . research problem research problem before conducting the electrical energy audit of the industry, the industry and workers were working in the environment in which old and inefficient energy consuming systems were used. some of the problems are mentioned below:- . inefficient lamps and/or ballasts . mounting height of lamps too high . reflectors of poor luminaries efficiency . maintenance of reflectors not proper due to dirt/dust accumulation . poor maintenance of wall, floor and roof reflectance levels . reduction in light output of lamps over time due to lumen depreciation . low voltage . methodology adopted in case industry parsh pharmaceuticals, ujjain, madhya pradesh, ayurvedic medicines are manufactured. energy audit is the key to a systematic approach for decision-making in the area of energy management. the purpose of this test is to calculate the installed efficacy in terms of lux/w/m for general lighting installation. the calculated value can be compared with the norms for specific types of interior installation for assessing improvement options. doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . issn: - issn: - issn: - step measure the floor area of the interior area = ------------------------m step calculate the room index ri = ----------------------------- step determine the total circuit watts of the installation by a power meter if a separate feeder for lighting is available. if the actual value is not known a reasonable approximation can be obtained by totaling up the lamp wattages including the ballasts: total circuit watts = ---------- step calculate watts per square metre, value of step / value of step w/m = ---------------------- industrial engineering journal june table : target lux/w/m² (w/m²/ lux) values for maintained illuminance on horizontal plane for all room indices and applications ( ) room index commercial lighting, (offices, retail stores etc.) & very clean industrial applications, standard or good colour rendering. ra: - industrial lighting (manufacturing areas, workshops, warehousing etc.) standard or good colour rendering. ra: - industrial lighting installations where standard or good colour rendering is not essential but some colour discrimination is required. ra: - ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) . ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) . ( . ) ( . ) ( . ) . ( . ) ( . ) ( . ) ( . ) ( . ) ( . ) calculate the room index: ri = l x w ———— hm(l + w) table : determination of measuring points( ) determination of measurement points minimum number of measurement points below and below and below and above installed load efficacy ratio (iler) the installed load efficacy ratio is defined as the ratio of installed load efficacy and targeted load efficacy iler = installed load efficacy/ target installed load efficacy iler indicates the efficiency of lighting end use. the following table can be used to qualify comments. table : indicators of performance based on iler ( ) iler assessment . or above satisfactory to good . to . review suggested . or less urgent action required the reasons for iler to be lower than desired can be due to any of the following. . inefficient lamps and/or ballasts . mounting height of lamps too high . reflectors of poor luminaire efficiency . maintenance of reflectors not proper due to dirt/dust accumulation . poor maintenance of wall, floor and roof reflectance levels . reduction in light output of lamps over time due to lumen depreciation table : different department and corresponding areas department total working area (m ) stores . mixing . filling section . packing . weight quality . labeling . tablet section . malt section . pulverising . office the detailed procedure to determine the installed load efficacy ratio (iler) is explained below in the form of table:- table :- steps involved in calculation of installed load efficacy ratio (iler) doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . issn: - issn: - issn: - step ascertain the average maintained illuminance by using lux merter, eav maintained eav. maint. = ------- step divide by to calculate lux per watt per square metre lux/w/m = --------------- step obtain target lux/watt/m lux for the type of interior/application and ri( ): targ et lux/w/m = ------------ step calculate installed load efficacy ratio ( / ) iler = -------------------- industrial engineering journal june . results & discussions before conducting the energy audit, the case organization has been working in the environment in which working conditions were not upto the standard level. due to this, different types of lightning issues arises. these problems have been discussed earlier. to overcome these problems it was decided to use the concept of energy audit in which installed load efficacy concept is used to find whether the installed setup is at the satisfactory level or not. after successfully implementing it encouraging results were obtained. these results are shown below in the form of tables. table : installed load efficacy ratio (iler) for store s. no calculation: installed load efficacy ratio (iler) unit value length of room m . width of room m . floor area m² . height of lamp from the plane of measurement hm . room index . total circuit watts w calculate watts per square metre w/ m² . measured average room illuminance lux installed lighting efficacy lux/w/ m² . target lighting efficacy from reference: bee lux/w/ m² installed load efficacy ratio (iler) . assessment review suggested similarly installed load efficacy ratio (iler) for different departments is mentioned below:- . for the packing section, the room index calculated is . , calculated installed light efficacy is . lux/w/m , and the target light efficacy as per bee standards is lux/w/m . so the calculated installed load efficacy ratio (iler) is . . this means that the review is suggested for better results. . for the labeling section, the room index calculated is . , calculated installed light efficacy is . lux/w/m , and the target light efficacy as per bee standards is lux/w/m . so the calculated installed load efficacy ratio (iler) is . . this means that urgent action is required for better results. . for the tablet section, the room index calculated is . , calculated installed light efficacy is . lux/w/m , and the target light efficacy as per bee standards is lux/w/m . so the calculated installed load efficacy ratio (iler) is . . this means that the result is satisfactory to good. now as per the results obtained by the above analysis of all the departments with the concept of installed load efficacy ratio (iler), it has been shown that some of the departments do not have illuminance as per the desired standard. so, to reduce the above effect and maintaining the required iler, the low efficient lightning has to be replaced with the efficient lightning. the possible replacements are suggested to solve the above problems. table :- replacing convention w cfl by watt led lamp sr. no. parameter units value ai conventional cfl no. aii rated power of existing watt cfl watt/ unit b operating hrs hrs/day c operating annual days days/year d unit consumed annually ( ai*aii*b*c)/ ) kwh/year . replacement e energy efficient w led lamp watt/unit doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . issn: - issn: - issn: - f unit consumed annually kwh/year . g energy saving (old- new annual consumption) kwh/year . h total annual energy cost saving @ rs. . per unit inr cost benefit calculation per unit cost@ rs. /- inr i total capital cost inr j labor & other cost inr@ /fix k total investment inr l net annual saving inr m simple payback (investment/annual savings) yrs . industrial engineering journal june fig. comparison of unit consumption by w cfl and w led lamp similarly the electrical unit consumption for the different replacements are:- . the annual unit consumption of quantity of t- & t- tube lights is kwh/year, which when replaced with t ( watt led tube light) consumes kwh/year, which is represented by fig . total energy saving within a year by replacing is about kwh/year and the net payback period is found to be . years. fig. comparison of unit consumption by w t- and t- tube and w t- led tube doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . issn: - issn: - issn: - industrial engineering journal june . the annual unit consumption of quantity of * watt cfl lights is kwh/year, which when replaced with watt led lamp consumes . kwh/year, which is represented by fig . total energy saving within a year by replacing is about . kwh/year and the net payback period is found to be . years. fig. comparison of unit consumption by * w cfl and w led lamp fig. comparison of unit consumption by w cfl and w t- led tube . the annual unit consumption of quantity of watt metal halide lights is kwh/year, which when replaced with watt led lamp consumes kwh/year, which is represented by fig . total energy saving within a year by replacing is about kwh/year and the net payback period is found to be . years. . the annual unit consumption of quantity of * cfl lights is . kwh/year, which when replaced with t- ( watt led tube) consumes . kwh/year, which is represented by fig . total energy saving within a year by replacing is about . kwh/year and the net payback period is found to be . years. doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . issn: - issn: - issn: - industrial engineering journal june fig. comparison of unit consumption by w mh lamp and w led lamp . conclusion like all other industries pharmaceutical industries are also facing the problems like energy mismanagement, low use of natural light, unnecessary use of lighting system, use of in efficient lighting system. these problems have been addressed in this study by implementation of installed load efficacy ratio technique in the pharmaceutical industry. in this case study, the existing lighting system with low illuminance as per the predefined standards have been suggested to replace with the efficient lighting system. after implementing the above recommendations highly encouraging results have been obtained. following conclusions have been drawn after assessing these results: . the installed load efficacy ratio for the different departments of the industry has been improved are:- i. the iler for stores has been improved from . to . , which is good and economic. ii. the iler for filling section has been improved from . to . , which is satisfactory to good. iii. the iler for packing section has been improved from . to . , which is satisfactory to good. iv. the iler for labeling section has been improved from . to . , which is satisfactory to good. . as the annual units consumption has been reduced to a great level without compromising the illuminance and the visibility of different sections so that the iler can be increased to a satisfactory level. . so after successful replacement of the energy inefficient lighting system with that of energy efficient one, a huge amount of saving has been achieved as well as greater illuminance is also achieved for better working conditions. to understand it in details the following table has been prepared, which represent the average payback period of the investment. table : simple payback period sr. no. energy conservation measures energy saving (kwh/yr) investment required (rs.) simple pay back period (year) replacing convention w cfl by watt led lamp . , /- . replacing convention t- & t- tube by t- ( watt led tube) , /- . replacing convention * w cfl by watt led lamp . , /- . replacing convention * w cfl by t- ( watt led tube) . , /- . replacing convention w mh by watt led lamp , , /- . replacing & w bulb by watt led tube , , /- . replacing watt exhaust fan by watt energy efficient exhaust fan , / - . total , . , /- . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . issn: - issn: - issn: - industrial engineering journal june references . kongara ajay, g.sudhakar, k.sasank, t.guru krishna; ; a case study on energy conservation & audit for household applications vol. , issue . matteo dongellini, cosimo marinosci, gian luca morini; ; energy audit of a industrial site: a case study. . p.loganthurai, s.parthasarathy, s.selvakumara, dr.v.rajasekaran; ; energy conservation measures in a technical institutional. . m r. g a n a p a t h i , d . m o g e r, d r. c h . s . n . m u r t h y, mr.manjunath.a ; ; icaer . nikola tanasic, goran jankes, mirjana stamenic, aleksandar nikolic, marta trninic and tomislav simonovic; ; potentials for reducing primary energy consumption through energy audit in the packaging paper factory. . arun govind m, gopinath k; ; optimizing the energy in an educational institution using energy audit technique; international journal of scientific research and engineering studies (ijsres); volume issue . . kaur poonam, thakur ritula; ; energy audit of a food industry; international journal of modern engineering research(ijmer); vol. ; issue . web sources: . https://beeindia.gov.in/sites/default/files/ ch .pdf (visited on / / ) . http://wikipedia.com (visited on / / ) . http://www.lrc.rpi.edu/programs/nlpip/lightinganswers/ lat /pc a.asp (visited on / / ) . http://eartheasy.com/blog/ / /led-bulbs-are-ready- to-light-your-home- -tips-you-should-know/(visited on / / ) authors piyush jain, research scholar, department of mechanical engineering, ujjain engineering college, ujjain (m.p.) india email: piyushjain @gmail.com dr. sc solanki, professor, department of mechanical engineering, ujjain engineering college, ujjain (m.p.) india dr. ravi nagaich, professor, department of mechanical engineering, ujjain engineering college, ujjain (m.p.) india pavan jain, director at parsh pharmaceutical, ujjain (m.p.) india doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . doi: . /iej. . . issn: - issn: - issn: - utilization of oil palm biodiesel solid residue as renewable sources for preparation of granular activated carbon by microwave induced koh activation utilization of oil palm biodiesel solid residue as renewable sources for preparation of granular activated carbon by microwave induced koh activation k.y. foo, b.h. hameed ⇑ school of chemical engineering, engineering campus, universit sains malaysia, nibong tebal, penang, malaysia h i g h l i g h t s " highlight the renewable use of oil palm biodiesel solid residue. " explore the potential of microwave heating. " low activation time of min. " high monolayer adsorption capacity for mb of . mg/g. a r t i c l e i n f o article history: received july received in revised form november accepted november available online december keywords: activated carbon adsorption isotherm microwave oil palm shell a b s t r a c t in this work, preparation of granular activated carbon from oil palm biodiesel solid residue, oil palm shell (psac) by microwave assisted koh activation has been attempted. the physical and chemical properties of psac were characterized using scanning electron microscopy, volumetric adsorption analyzer and ele- mental analysis. the adsorption behavior was examined by performing batch adsorption experiments using methylene blue as dye model compound. equilibrium data were simulated using the langmuir, freundlich and temkin isotherm models. kinetic modeling was fitted to the pseudo-first-order, pseudo-second-order and elovich kinetic models, while the adsorption mechanism was determined using the intraparticle diffusion and boyd equations. the result was satisfactory fitted to the langmuir isotherm model with a monolayer adsorption capacity of . mg/g at �c. the findings support the potential of oil palm shell for preparation of high surface area activated carbon by microwave assisted koh activation. � elsevier ltd. all rights reserved. . introduction the world is facing the worst energy crisis in its entire history. for the past two decades, the search for alternative energy, namely the solar, wind, hydrothermal, geothermal and biofuel, which is renewable and environmental friendly, has been carried out exten- sively (foo and hameed, a). according to the estimation pre- dicted by the international energy agency, the global energy consumption is foreseen to increase approximately . % by , with . % of crude oil, . % of coal, . % of natural gas, . % of nuclear energy and . % of hydroelectricity (iea, ). at the current production rates, the global proven reserves for crude oil and natural gas are expected to last for the next . and . years (ong et al., ). the progressive escalation of oil price and diminishing fossil fuel reserves has led to a shift towards alternative fuel sectors (foo and hameed, b). among all, biodiesel, defined as the mono-alkyl esters of long chain fatty acids, is produced from biological sources such as veg- etable oils or animal fats using a biological process known as tran- sestification (foo and hameed, a). biodiesel has been identified as the most attractive and practical choice to replace fos- sil fuel as the main source of energy, due to the similarity with con- ventional diesel in terms of chemical structure and energy content (foo and hameed, b). additionally, no modification in diesel engine is required as biodiesel is compatible with the exiting en- gine model (mendow et al., ). today, the biodiesel is booming in europe and the united states. in malaysia, the national palm oil biofuel policy framework has been drafted by the government, and biodiesel plants are fully operational with capacity of producing million tonnes of biodie- sel per year (mekhilef et al., ). the refining and fractionation process however, is accompanied by the generation of oil palm bio- mass, in the form of oil palm trunk, empty fruit bunch, fiber, shell and discharged waste of palm oil mill effluent (pome) (foo and hameed, a). in the formal practice, some quantity of these - /$ - see front matter � elsevier ltd. all rights reserved. http://dx.doi.org/ . /j.biortech. . . ⇑ corresponding author. tel.: + ; fax: + . e-mail address: chbassim@eng.usm.my (b.h. hameed). bioresource technology ( ) – contents lists available at sciverse sciencedirect bioresource technology j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / b i o r t e c h http://crossmark.dyndns.org/dialog/?doi= . /j.biortech. . . &domain=pdf http://dx.doi.org/ . /j.biortech. . . mailto:chbassim@eng.usm.my http://dx.doi.org/ . /j.biortech. . . http://www.sciencedirect.com/science/journal/ http://www.elsevier.com/locate/biortech analytical research on waste heat recovery and utilization of chinas iron & steel industry energy procedia ( ) – - © published by elsevier ltd. selection and/or peer-review under responsibility of the organizing committee of nd international conference on advances in energy engineering (icaee). doi: . /j.egypro. . . available online at www.sciencedirect.com available online at www.sciencedirect.com energy procedia energy procedia ( ) – www.elsevier.com/locate/procedia nd international conference on advances in energy engineering analytical research on waste heat recovery and utilization of china’s iron & steel industry ma guang-yua,b,*, cai jiu-jua, zeng wen-weia, dong huia, a* asepa key laboratory on eco-industry, northeastern university, shenyang , china bansteel technology center, anshan iron and steel group corporation，anshan , china abstract as energy crisis become increasingly prominent, the energy consumption has became the main problem which restricts the sustainable development of china’s iron & steel industry. the recovery and utilization of different kinds of waste heat can effectively reduce energy consumption, the research of the scientifical recovery and utilization of waste heat become very important. the current situation and status of recovery and utilization of waste heat in the china’s iron & steel industry will be analysed from some aspects such as the quality and the source process of waste heat, based on them the potential and develop directions will be pointed out, combining with the analysis of the basic principle using energy scientifically, the mode of the recovery and utilization of waste heat is given, it is hoped that it can promote the scientifical and rapid development of recovery and utilization of waste heat of china’s iron & steel industry. © published by elsevier ltd. keywords:waste heat; recovery and utilization; iron& steel . introduction the iron & steel industry is energy-intensive industry. its energy consumption is very large, which accounts for ~ % of the total energy consumption and to % of the total industrial energy consumption of china.compared with the international advanced level, the energy consumption of per ton steel of china is about % higher than theirs[ ]. as energy crisis become increasingly prominent, chinese government pay more attention to save energy and eliminate backward production capacity, * corresponding author. tel.: + - - ; . e-mail address: dongh@smm.neu.edu.cn.. © published by elsevier ltd. selection and/or peer-review under responsibility of the organizing committee of nd international conference on advances in energy engineering (icaee). open access under cc by-nc-nd license. open access under cc by-nc-nd license. http://creativecommons.org/licenses/by-nc-nd/ . / http://creativecommons.org/licenses/by-nc-nd/ . / ma guang-yu et al.\ / energy procedia ( ) – ma guang-yu et al/ energy procedia ( ) – energy problem has became a main point which restricts the sustainable development of china’s iron & steel industry. a large number of waste heat is generated when it consumes in promoting the transformation of materials in the iron & steel industry, the recycling of different kinds of waste heat can effectively reduce energy consumption. for waste heat recovery and utilization of iron and steel industry , it has been studied as early as the s in china, many researchs show that waste heat recovery and utilization of iron and steel industry has a huge potential, its further recovery and utilization is the main direction of energy saving in the iron & steel industry in future[ - ]. in the paper, the current situation and status of recovery and utilization of waste heat in the china’s iron & steel industry will be analysed from some aspects such as the quality, the category, the source process of waste heat, based on them the potential and develop directions will be pointed out, combining with the analysis of the basic principle using energy scientifically, the mode of the recovery and utilization of waste heat is given, it is hoped that it can promote the scientifical and rapid development of recovery and utilization of waste heat of china’s iron & steel industry. . analysis of waste heat recovery and utilization of china’s iron & steel industry the scope and definition of waste heat of iron & steel industry is a foundation which analyses the level of recovery and utilization of waste heat, different scope and definition may lead to different results. therefore, the definition and the statistical range of waste heat are given before specific analysis. the waste heat refered in the paper is the heat carrier which can release energy with environmental temperature（ ℃）as a reference and other kinds of energy expect heat (pressure energy, chemical energy) produced by the iron & steel production process. the statistical range of waste heat includes the main processes such as coking, sintering/pelletizing, ironmaking, steelmaking and rolling etc. but energy conversion processes such as oxygen generator、electricity generation expect coking and the auxiliary raw material preparation processes such as iron alloy, carbon, refractory materials, metallurgical are not included. . . analysis of recovery and utilization of different quality waste heat the evaluation of waste heat resources not only depends on quantity, but also quality. the division of quality according to temperature level, has three categories such as high grade, medium grade and low grade. the high grade refers to the waste heat resources whose temperature is higher than ℃ , including high temperature flue gas such as coke oven gas, converter gas, electric furnace gas and heating furnace flue gas etc. among them the temperature of converter gas up to ℃, the heating furnace flue gas also can reach ℃; high temperature liquid such as high temperature iron slag, steel slag and table .the situation of recovery and utilization of different quality waste heat of china’s iron & steel industry the quality of waste heat quantity of total （gj/t-s） quantity of recovery （gj/t-s） rate of recovery (%) low grade . . . medium grade . . . high grade . . . high temperature water etc.; high temperature solid waste heat such as high temperature sintering materials, high temperature coke, high temperature steel etc. the medium grade refers to the waste heat whose temperature at to ℃, including blast furnace gas and sintering flue gas, exhaust gas ma guang-yu et al.\ / energy procedia ( ) – ma guang-yu/ energy procedia ( ) – recovery of waste heat from the primary after flue gas etc. low grade refers to the waste heat whose temperature below ℃, including waste steam and hot water, all kinds of low temperature flue gas and low temperature materials etc. as the statistics base on per ton steel, the situation of recovery and utilization of different quality waste heat of china’s iron & steel industry is shown in table . the proportion of different grade of waste heat resources not recycling is shown in figure . low grade % medium grade % high grade % low grade medium grade high grade fig. . the proportion of different grade of waste heat resources not recycling as the table shows, the recovery and utilization of high temperature waste heat is most, its rate is up to . ％, the secondly is the medium grade waste heat, the rate reaches . %, however the rate of low grade waste heat is less than %. the rate of medium or high quality waste heat are not very high, the recovery and utilization of low grade is almost no begin. figure shows that the rate not recycling of high, medium and low grade waste heat resources is %, %, %, the low grade waste heat resources accounted for nearly half of all. in conclusion, the development of low quality of waste heat will be a key point in the future way of recovery and utilization of waste heat. . . analysis of recovery and utilization of different process waste heat table . the situation of the recovery and utilization of different process waste heat process quantity of total （gj/t-s） quantity of recovery （gj/t-s） rate of recovery (%) coking . . . sintering/pelletizing . . . ironmaking . . . steelmaking . . . rolling . . . the typical metallurgy is a multiple process, which includes coking, sintering/pelletizing, ironmaking, steelmaking and rolling. the difficulty of recovery and utilization of waste heat and the recovery rate is different because of the diverse of the amount, the quality and the category. the table shows that the situation of the recovery and utilization of different process waste heat, the figure shows the proportion of different process of waste heat resources not recycling. as the above table and figure show, the waste heat resource of ironmaking process is the largest, although the recovery and utilization rate is largest, the rate not recycling is also the largest, basically there is no recycling of the slag, the cooling water and the coal of blast furnace, so generating steam through using the dry granulation for blast furnace slag, developing new recovery and utilization ma guang-yu et al.\ / energy procedia ( ) – ma guang-yu et al/ energy procedia ( ) – technology for low-grade cooling water and strengthening recovery of blast furnace gas will be the key point for recovery and utilization of of ironmaking process waste heat. through the recovery and utilization rate of coking process is lowest, the reason is that the sensible heat of coke oven gas isn’t used, the popularity rate of dry quenching is very low, it is obvious that with the promotion of dry quenching technology and wet coal technology, the sensible heat of coke and coke oven gas will be used and the rate of coking process will be largely improved . the waste heat of sintering/pelletizing process belongs to the medium and low grade, the rate is low because they are diffcult to utilize, with the promotion of the classification recycling and cascade utilization technology of the sintering waste heat, the recovery rate of sintering process will be improved. at present, each process has the typical advanced technology which has been applicated in the domestic and foreign iron & steel enterprise. according to estimation, the recovery rate will be largely improved if the typical advanced technology be used in each process. so the energy consumption per ton steel will be greatly reduced when the typical advanced technology be used in china’s iron & steel enterprise, it can promote the further development of china’s iron & steel industry. coking % ironmaking % steelmaking % rolling % sintering/ pelletizing % coking sintering/pelletizing ironmaking steelmaking rolling fig. . the proportion of different process of waste heat resources not recycling now the recovery rate of waste heat resource (including vice produce gas)is usually next to % in foreign advanced iron & steel enterprises, such as japanese nippon steel reaches to %, but most of the iron & steel enterprises in china is just reach % ~ %[ ]. the reason is: ① the manufacturing processes can't recover waste heat timely and adequately, meanwhile the recovery rate is low and the amount is insufficient; ② the utilization of all sorts of heat recoveried is not in a more effective way, the hot air, steam, coal gas which have been recovered is diffused because of low temperature, heat source supply by instability or the balance of supply and demand of seasonal effects and so on. ③ the key technology of recovery and utilization of waste heat has been left behind, almost all major equipments depend on import, the recovery heat is either depreciation or instability and unable to meet the user's requirement, which make the large number of low-grade heat is no avail. ④ some enterprises are small scale, low productivity, backward equipment, at the same time because it is a large investment that import equipments which used for recovery waste heat, it always loss outweighs the gain, which affect enterprise's enthusiasm of recoverying waste heat. . study on high efficient mode of waste heat recovery and utilization in iron & steel industry the waste heat of the iron & steel industry is not only recovered and utilized but also required the scientific and reasonable way, the research methods which are studied the recovery and utilization proper way of waste heat have the thermal equilibrium analysis, exergy analysis and energy level analysis. the ma guang-yu et al.\ / energy procedia ( ) – ma guang-yu/ energy procedia ( ) – first law of thermodynamics is used as the theoretical basis of the thermal equilibrium analysis, so the method just simply inspect the recovery of waste heat from the quantity relationships of the conservation of energy, not consider the quality of the heat and their changes, so the thermal efficiency index can't reflect the rationality of the utilization; the second law of thermodynamics theory is used as the theoretical basis of exergy analysis, so the method just consider utilization of convertible part of waste heat, but are blind to the other part which can’t be used, on the contrary, the exergy efficiency index investigate the recovery and utilization of waste heat from the unequilibrium of energy; energy level analysis method in essence is a component part of the second law of thermodynamics analysis, which still investigate whether the recovery of waste heat compliance with the utilization of heat energy which users needed on the quantity relationships of energy level's balance, just makes the difference of two energy level as the evaluation index, and considers only the situation about quality match between supplier and users, also ignore its' quantity change[ , ]. in short, the recovery and utilization of waste heat must be based on the first and second law of thermodynamics, not only to sees the number of heat loss, but also considers the quality reduction. overemphasising on the any one is one-sided. figure is the heat(exergy)flow diagram of the recovery and utilization system of waste heat. in the figure the waste heat of input system is q (energy level is Ω ), output heat is q (energy level is Ω ), output power is w ( energy level is ), the heat loss of system is ql (energy level is Ωl). so the heat efficiency of system, output heat and the total energy level of system, system's exergy efficiency respectively by type ( ), ( ), ( ) says: fig. . the heat(exergy)flow diagram of the recovery and utilization system of waste heat q wq + =η ( ) αα −+Ω= + +Ω =Ω wq wq ( ) ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ Ω ΔΩ −= Ω Ω = ηηη ( ) in formula, α is the ratio of output heat accounted for the total output energy; ΔΩ is the energy level difference between input heat and output heat. from formula ( ) it can be seen that exergy efficiency depends on the thermal efficiency of the system and the difference between input heat level and output heat level, the former one is related to first law of thermodynamics, the latter is related to second law of thermodynamics. t is environmental temperature, t is the temperature of waste heat, t is the temperature of output heat, |ΔΩ|r is energy level difference during pure thermal utilization, |ΔΩ|d is energy q （ Ω ） q （ Ω ） the recovery and utilization system of waste heat w ql（ lΩ ） ma guang-yu et al.\ / energy procedia ( ) – ma guang-yu et al/ energy procedia ( ) – level difference during pure power utilization, the energy level difference between input and output heat is a function of temperature: from formula ( ): t t t t α−=ΩΔ ( ) when t = t , | Δ Ω |r =| Δ Ω |d, the effect of thermal utilization is equal to power utilization, when t > t , Ω > / , | Δ Ω |r > | Δ Ω |d, the effect of power utilization is better than thermal utilization, when t < t , Ω < / , | Δ Ω |r < | Δ Ω |d, the effect of thermal utilization is superior to power utilization. thus the general principle of recycling waste heat resources is: according to the waste heat resources quantity, quality (temperature) and customers' demand and the principle of matching energy level, recovered by the quality，temperature correspond and cascade utilization. ① if there are suitable heat users, using waste heat directly is most economic, for example, the sensible heat of product are supplied to the next process without transition, waste heat is used to preheat air and gas, preheat or dry material, product steam and hot water. the redundant quantity of heat can be used to refrigeration when users reduce in the summer.②for high temperature waste heat recovery should be adopted by power recovery, such as power generation or cogeneration. ③ the low temperature waste heat should be utilized directly, for which can't be utilized directly, it can be used as the low-temperature heat source of heat pump system, used after improving the temperature level.④the medium grade waste heat resources can be used by heat recovery or power recovery according to the specific temperature. according to the above analysis, the mode of waste heat recovery and utilization in iron & steel industry can be concluded as shown in figure : fig. . the mode of waste heat recovery and utilization in iron & steel industry ma guang-yu et al.\ / energy procedia ( ) – ma guang-yu/ energy procedia ( ) – . conclusions all analyses show:①the low-grade waste heat in china’s iron & steel industry has not been used basically, it is the key point of the recovery and utilization of waste heat of iron & steel industry in future; ②the recovery rate of coking and sintering process is relatively low, should strengthen research and extension in coke dry quenching technology and grade recovery and cascade utilization of sintering waste heat resources; ③the recovery and utilization of waste heat in scientifical way should depend on the first and second law of thermodynamics and accorrd to the quantity, the temperature and user's demand recovering by the quality，temperature correspond and cascade utilization. it is the fundamental of the recovery and utilization of waste heat of iron & steel industry. acknowledgements this work was supported by the natural science foundation of liaoning province contract no. and the science and technology plan program of shenyang city contract no. 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[ ] tang xue-zhong. conversion and utilization of thermal energy. beijing: the metallurgical industry press; . special issue editorial: functional oxide based thin-film materials crystals editorial special issue editorial: functional oxide based thin-film materials dong-sing wuu department of materials science and engineering, national chung hsing university, xingda road, taichung , taiwan; dsw@dragon.nchu.edu.tw received: march ; accepted: march ; published: march ���������� ������� protective oxide coatings, such as al o and y o coatings, are widely used in semiconductor industries because of their hardness, high wear resistance, dielectric strength, high corrosion resistance, and chemical stability for plasma chambers [ ]. thin-film oxide barrier coatings with ultra-low permeation also received much attention in the industries of pharmaceuticals, food, beverage packaging, and organic light-emitting display applications [ ]. besides these protective functions, the oxide thin-film materials and nanostructures are extraordinary multifunctional crystals with a huge range of emerging application domains, such as sensors, displays, light emitters, photovoltaics, spintronics, piezoelectric motors, biotechnology, capacitors, transparent electronics, and next-generation memories [ ]. these become the original motivation for proposing this special issue—functional oxide-based thin-film materials. the functional oxide crystal has several favorable properties, including good transparency, high conductivity, a wide bandgap, and strong luminescence. thin-film oxide materials have been grown on various substrates by hydrothermal, sol–gel, chemical bath deposition, sputtering, atomic layer deposition, pulsed laser deposition, chemical vapor deposition (cvd), hot filament cvd, plasma-enhanced cvd, etc. a number of breakthroughs over the past few years have driven an exponential energy in the research activity of this field. this special issue on functional oxide-based thin-film materials aims at gathering together some of the specialists working with device applications, to shed light on the properties and behavior of thin-film oxides. the papers cover many aspects of thin-film science and technology from thin film to nanostructure, from material properties to optoelectronic applications, thus reflecting the many interests of the community of scientists active in the field. gallium oxide, a wide bandgap material, has received much attention in several possible applications. in [ ], lin and co-workers report the porous gan layers surrounding the mesa region were transformed into insulating gaox layers in a reflector structure through a lateral photoelectrochemical (pec) oxidation process. the electroluminescence emission intensity was localized at the central mesa region by forming the insulating gaox layers in a reflector structure as a current confinement aperture structure. the pec light-emitting device structure with a current-confined aperture surrounded by insulating gaox layers has the potential for ingan resonance cavity light source applications. in [ ], wuu and co-workers report the synthesis and characterization of gallium oxide (ga o ) thin films fabricated on glass substrates using a combination of chemical bath deposition and a post-annealing process. the nanocrystalline α-ga o films obtained from gaooh after annealing showed the photodegraded % of the methylene blue in a solution irradiated under an ultraviolet lamp for h. these results suggest that α-ga o thin films can be very useful alternatives for the photocatalytic degradation of dyes during wastewater treatment. zinc oxide (zno) is a versatile and inexpensive semiconductor with a wide direct band gap that has applicability in several scientific and technological fields. in [ ], amakali and co-workers report the synthesis of zno thin films via two simple and low-cost synthesis routes, i.e., the molecular precursor crystals , , ; doi: . /cryst www.mdpi.com/journal/crystals http://www.mdpi.com/journal/crystals http://www.mdpi.com https://orcid.org/ - - - http://www.mdpi.com/ - / / / ?type=check_update&version= http://dx.doi.org/ . /cryst http://www.mdpi.com/journal/crystals crystals , , of method and the sol–gel method, which were deposited successfully on microscope glass substrates. in [ ], díaz-becerril et al. have investigated the tantalum-doped zno structures synthesized on silicon substrates by using a hot filament chemical vapor deposition reactor. green photoluminescence (pl) was observed by the naked eye when ta-doped samples were illuminated by ultraviolet radiation and confirmed by photoluminescence spectra. the pl intensity on the ta-doped zno increased from those undoped samples up to eight times and the resistivity and the sheet resistance also decrease when there is a greater amount of tantalum in the film. an interesting investigation into the series of nanometer scale ( – nm) hfo thin films grown on si substrates under different conditions by atomic vapor deposition (avd) is reported by feng et al. in [ ]. the comprehensive studies demonstrate that appropriate substrate temperature and oxygen flow are essential to the structure, chemical composition, and optical constants from the surface and interface of the hfo films deposited by avd. this work with integrated experiment measurements and analyses has enhanced our understanding of avd-grown hfo advanced materials. an entirely different perspective on thin film oxides is presented by chang and chan. in their paper, [ ], they investigated the heavily doped wide band gap semiconductors like aluminum-doped zinc oxide (azo) and tin-doped indium oxide (ito) for low emissivity glass (low-e glass), which is often used in energy-saving buildings. the emissivity and average visible transmittance for h /n = / plasma annealed azo/ito were . % and %, respectively, lying in the range of commercially used low emissivity glass. supercapacitors, excellent energy storage devices, can effectively alleviate the current energy crisis. based on their obvious advantages, such as simple design, high-power density, a long cycling lifetime, and a short charge/discharge rate, supercapacitors have attracted much research interest in recent years. zheng and co-workers in [ ] have synthesized a nio@zno (nzo) hybrid with different reaction times by a green hydrothermal method. a highest energy density of . wh kg− can be achieved at a power density of . w kg− . these desirable electrochemical properties demonstrate that the nzo hybrid is a promising electrode material for a supercapacitor. finally, we also presented a contribution concerned with a review article, using d zinc oxide (zno) as a representative nanomaterial [ ]. this article reviews the fabrication methods of d zno nanostructures—including chemical vapor deposition, hydrothermal reaction, and electrochemical deposition—and the influence of the growth parameters on the growth rate and morphology. important applications of d zno nanostructures in optoelectronic devices are described. several approaches to improve the performance of d zno-based devices, including surface passivation, localized surface plasmons, and the piezo-phototronic effect, are summarized. to conclude, i believe that this special issue on functional oxide-based thin-film materials touches on the latest advancements in several aspects related to material science: the synthesis of novel oxide, photoluminescence characteristics, photocatalytic ability, energy storage, light emitter studies, low emissivity glass coatings, and investigations of both nanostructure and thin film properties. i wish to express my deepest and sincere gratitude to all authors who contributed, for having submitted manuscripts of such excellent quality. i also wish to thank the editorial office of crystals for the fast and professional handling of the manuscripts during the whole submission process and for the help provided. conflicts of interest: the authors declare no conflict of interest crystals , , of references . lin, t.-k.; wang, w.-k.; huang, s.-y.; tasi, c.-t.; wuu, d.-s. comparison of erosion behavior and particle contamination in mass-production cf /o plasma chambers using y o and yf protective coatings. nanomaterials , , . [crossref] [pubmed] . hsu, c.-h.; lin, y.-s.; wu, h.-y.; zhang, x.-y.; wu, w.-y.; lien, s.-y.; wuu, d.-s.; jiang, y.-l. deposition of silicon-based stacked layers for flexible encapsulation of organic light emitting diodes. nanomaterials , , . [crossref] [pubmed] . peng, w.-c.; chen, y.-c.; he, j.-l.; ou, s.-l.; horng, r.-h.; wuu, d.-s. tunability of p- and n-channel tiox thin film transistors. sci. rep. , , . [crossref] [pubmed] . chen, y.-y.; jhang, y.-c.; wu, c.-j.; chen, h.; lin, y.-s.; lin, c.-f. fabrication of gaox confinement structure for ingan light emitter applications. crystals , , . [crossref] . yeh, c.-y.; zhao, y.-m.; li, h.; yu, f.-p.; zhang, s.; wuu, d.-s. growth and photocatalytic properties of gallium oxide films using chemical bath deposition. crystals , , . [crossref] . amakali, t.; daniel, l.s.; uahengo, v.; dzade, n.y.; leeuw, n.h. structural and optical properties of zno thin films prepared by molecular precursor and sol–gel methods. crystals , , . [crossref] . herrera, v.; díaz-becerril, t.; reyes-cervantes, e.; garcía-salgado, g.; galeazzi, r.; morales, c.; rosendo, r.; nieto-caballero, f.g. highly visible photoluminescence from ta-doped structures of zno films grown by hfcvd. crystals , , . [crossref] . luo, x.; li, y.; yang, h.; liang, y.; he, k.; sun, w.; lin, h.-h.; yao, s.; lu, x.; wan, l.; et al. investigation of hfo thin films on si by x-ray photoelectron spectroscopy, rutherford backscattering, grazing incidence x-ray diffraction and variable angle spectroscopic ellipsometry. crystals , , . [crossref] . chang, s.-c.; chan, h.-t. effect of nitrogen flow in hydrogen/nitrogen plasma annealing on aluminum-doped zinc oxide/tin-doped indium oxide bilayer films applied in low emissivity glass. crystals , , . [crossref] . zheng, j.; zhang, r.; cheng, k.; xu, z.; yu, p.; wang, x.; niu, s. research on the high-performance electrochemical energy storage of a nio@zno (nzo) hybrid based on growth time. crystals , , . 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[crossref] © by the author. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . /nano http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /nano http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /s - - - http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /cryst http://dx.doi.org/ . /cryst http://dx.doi.org/ . /cryst http://dx.doi.org/ . /cryst http://dx.doi.org/ . /cryst http://dx.doi.org/ . /cryst http://dx.doi.org/ . /cryst http://dx.doi.org/ . /cryst http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	references [pdf] the molecular mechanisms affecting n-acetylaspartate homeostasis following experimental graded traumatic brain injury | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /molmed. . corpus id: the molecular mechanisms affecting n-acetylaspartate homeostasis following experimental graded traumatic brain injury @article{pietro themm, title={the molecular mechanisms affecting n-acetylaspartate homeostasis following experimental graded traumatic brain injury}, author={v. di pietro and a. m. amorini and b. tavazzi and r. vagnozzi and a. logan and g. lazzarino and s. signoretti and a. belli}, journal={molecular medicine}, year={ }, volume={ }, pages={ - } } 	v. di pietro, a. m. amorini, + authors a. belli 	published 	biology, medicine 	molecular medicine to characterize the molecular mechanisms of n-acetylaspartate (naa) metabolism following traumatic brain injury (tbi), we measured the naa, adenosine triphosphate (atp) and adenosine diphosphate (adp) concentrations and calculated the atp/adp ratio at different times from impact, concomitantly evaluating the gene and protein expressions controlling naa homeostasis (the naa synthesizing and degrading enzymes n-acetyltransferase -like and aspartoacylase, respectively) in rats receiving either… expand view on springer pure-oai.bham.ac.uk save to library create alert cite launch research feed share this paper citationshighly influential citations background citations methods citations results citations view all figures and topics from this paper 	 figure 	 figure 	 figure 	 figure 	 figure 	 figure view all figures & tables 	traumatic brain injury 	n-acetylaspartate 	adenosine triphosphate 	adenosine diphosphate 	brain injuries 	brain concussion 	acyltransferase 	t cell homeostasis 	drug development 	aspa gene citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency metabolic, enzymatic and gene involvement in cerebral glucose dysmetabolism after traumatic brain injury. 	a. m. amorini, g. lazzarino, + authors b. tavazzi 	biology, medicine 	biochimica et biophysica acta 	 	 	 save alert research feed extracellular n-acetylaspartate in human traumatic brain injury 	j. shannonrichard, van der heidesusan, + authors l. h. carpenterkeri 	medicine 	 	 	 save alert research feed extracellular n-acetylaspartate in human traumatic brain injury 	r. j. shannon, susan van der heide, + authors k. carpenter 	medicine 	journal of neurotrauma 	 	 	highly influenced 	pdf 	view excerpts, cites results and background save alert research feed neither excessive nitric oxide accumulation nor acute hyperglycemia affects the n-acetylaspartate network in wistar rat brain cells 	m. zyśk, p. pikul, r. kowalski, k. lewandowski, m. sakowicz-burkiewicz, t. pawełczyk 	chemistry, medicine 	international journal of molecular sciences 	 	pdf save alert research feed transcriptional regulation of n-acetylaspartate metabolism in the xfad model of alzheimer's disease: evidence for neuron–glia communication during energetic crisis 	samantha zaroff, p. leone, v. markov, j. francis 	biology, medicine 	molecular and cellular neuroscience 	 	 	 save alert research feed pyruvate dehydrogenase and tricarboxylic acid cycle enzymes are sensitive targets of traumatic brain injury induced metabolic derangement 	g. lazzarino, a. m. amorini, + authors a. belli 	chemistry, medicine 	international journal of molecular sciences 	 	 	pdf 	view excerpts, cites background, results and methods save alert research feed disturbances of cerebral metabolism of aspartate, glutamate, and n-acetylaspartate after traumatic brain injury according to h magnetic resonance spectroscopy 	p. e. menshchikov, n. semenova, + authors s. d. varfolomeev 	chemistry 	 	 save alert research feed fusion or fission: the destiny of mitochondria in traumatic brain injury of different severities 	v. di pietro, g. lazzarino, + authors a. belli 	biology, medicine 	scientific reports 	 	 	pdf save alert research feed dynamin and reverse-mode sodium calcium exchanger blockade confers neuroprotection from diffuse axonal injury 	a. omelchenko, a. shrirao, + authors b. firestein 	medicine 	cell death & disease 	 	 	pdf save alert research feed low molecular weight dextran sulfate (ilb®) administration restores brain energy metabolism following severe traumatic brain injury in the rat 	g. lazzarino, a. m. amorini, + authors a. logan 	chemistry, medicine 	antioxidants 	 	pdf 	view excerpts, cites results and background save alert research feed ... ... references showing - of references sort byrelevance most influenced papers recency the protective effect of cyclosporin a upon n-acetylaspartate and mitochondrial dysfunction following experimental diffuse traumatic brain injury. 	s. signoretti, a. marmarou, + authors r. vagnozzi 	medicine 	journal of neurotrauma 	 	 	view excerpts, references background save alert research feed n-acetylaspartate and n-acetylaspartylglutamate 	e. benarroch 	chemistry, medicine 	neurology 	 	 	view excerpt, references background save alert research feed extracellular n‐acetylaspartate depletion in traumatic brain injury 	a. belli, j. sen, + authors g. lazzarino 	medicine 	journal of neurochemistry 	 	 save alert research feed cerebral oxidative stress and depression of energy metabolism correlate with severity of diffuse brain injury in rats 	b. tavazzi, s. signoretti, + authors r. vagnozzi 	medicine 	neurosurgery 	 	 	view excerpts, references background save alert research feed potentially neuroprotective gene modulation in an in vitro model of mild traumatic brain injury 	v. pietro, a. m. amorini, + authors a. belli 	biology, medicine 	molecular and cellular biochemistry 	 	 save alert research feed evidence for mitochondrial and cytoplasmic n-acetylaspartate synthesis in sh-sy y neuroblastoma cells 	p. arun, j. moffett, a. namboodiri 	biology, medicine 	neurochemistry international 	 	 	pdf 	view excerpt, references background save alert research feed substrate delivery and ionic balance disturbance after severe human head injury. 	m. reinert, b. hoelper, e. doppenberg, a. zauner, r. bullock 	medicine 	acta neurochirurgica. supplement 	 	 save alert research feed reversible loss of n-acetylaspartate after -min transient middle cerebral artery occlusion in rat: a longitudinal study with in vivo proton magnetic resonance spectroscopy 	j. qian, b. qian, hao lei 	medicine 	neurochemical research 	 	 	view excerpt, references background save alert research feed molecular identification of aspartate n-acetyltransferase and its mutation in hypoacetylaspartia. 	e. wiame, d. tyteca, + authors e. van schaftingen 	biology, medicine 	the biochemical journal 	 	 	pdf save alert research feed methamphetamine-induced neuronal protein nat l is the naa biosynthetic enzyme: implications for specialized acetyl coenzyme a metabolism in the cns 	prasanth s. ariyannur, j. moffett, p. manickam, n. pattabiraman, a. namboodiri 	biology, medicine 	brain research 	 	 	pdf save alert research feed ... ... related papers 	abstract 	figures and topics 	 citations 	 references 	related papers stay connected with semantic scholar sign up about semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue page - © mat journals . all rights reserved journal of optical communication electronics volume issue iot based power theft detection prof. sagar shinde ,* sachin maskar , anjali pise , sagar salunkh assistant professor, department of electronics and telecommunication, d y patil college of engineering, ambi, pune, maharashtra, india bachelor of engineering, department of electronics and telecommunication, d y patil college of engineering, ambi, pune, maharashtra, india *email: sagar.shinde@dyptc.edu.com doi: http://doi.org/ . /zenodo. abstract the main objectives of this system are described clearly as follows: theft of electricity increases the costs paid by farmer and can have serious safety consequences. many farmers are taking benefits of electricity. . but not all farmers are having legal electricity connection. only those who have taken legal connection are paying the electricity charges. the farmers who are having legal electricity connection are paying charges of illegal connections and they don’t have any idea about this theft of electricity. this system is basically developed for the welfare of farmers. we can use this system for the society, but installation charge more as compare to the electricity theft. meter readings and rate every month send to the electricity providers through the iot. adding with these setup an efficient internet of things (iot) is defined, which portraits the global connection environment to the users and allow them to view the status of meter reading and theft associations globally from anywhere at any time. theft of electricity has a material impact on customers in terms of cost and safety. we consider that the existing regulatory framework does not adequately encourage suppliers to be proactive in detecting theft. in this document we are requesting views on proposed new supply license obligations to strengthen the arrangements for tackling theft and on the proposed role of distribution network operators (dnos) in tackling theft when it is not responsibility of suppliers. we are also consulting on additional policy measures and proposals to support suppliers in investigating, detecting and preventing theft. for all the entire system is useful for prevention of thefts and globally connected medium to portrait the meter reading through the iot to its customers effectively. keywords: iot, wi-fi, power distribution system, distribution network operator, microcontroller, lcd, adc. introduction theft of electricity increases the costs paid by farmers and can have serious safety consequences. in particular, when it detects electricity theft by one of its customers, the supplier may incur liabilities relating to generation, network and balancing costs associated with the entry to the settlement system of estimates of the volume of electricity stolen by that people. detecting electricity theft has been traditionally addressed by physical checks by the electricity provider company. the stolen electricity find out by the smart iot system. this technique measures all electricity used by the farmer and stolen by the illegal license customer. other hand it will measure the running electricity losses, this losses can be consider for the more accuracy of power theft. . common methods of theft range from compromising the physical security of meters to directly connecting loads to electricity distribution lines. default of payments has been a major problem, due to suboptimal levels of monitoring and enforcement. the lack of technology and insufficient distributor incentives were the major contributors to this problem. voltage divider circuit is used to measure the high incoming current http://doi.org/ page - © mat journals . all rights reserved journal of optical communication electronics volume issue from the power meter and shown in lcd display. if you add load to the power meter it consume some power this value is shown in lcd. voltage divider circuit is used to find the voltage level from main supply and shown in lcd. this voltage value is sent to iot. this alert message is received by distribution network operator instantly through web. the web message contains recent current, voltage and usage values. units are displaying on the lcd module display. in the internet of things (iot) model, many of the living and non – living things that encompass us will be on the internet in one form or another. driven by the popularity of gadgets empowered by wire - less technological innovation such as radio frequency identification, wireless - fidelity, embedded sensor, iot has moved out from its beginning stage and it is actually on the edge of changing the present fixed inter - net into a well featured upcoming internet. today the world is facing such an environment that offers challenges. energy crisis is the main problem faced by our farmer. a relevant system to control and monitor the power usage is one of the solutions for this problem. one approach through which today’s energy crisis can be addressed is through the reduction of power usage in agricultures. the electricity usages by the farmers are increasing rapidly and also burden on electricity offering divisions is sharply increasing. the farmers must be facilitated by giving them an ideal solution: - i.e. the concept of iot (internet of things) meters and on the other hand service provider end can also be informed about electricity thefts using theft detection unit. by keeping above factors, the concept of iot meters thrived consisting of three different units: microcontroller unit, voltage divider circuit and communication unit. the paper describes arm microprocessor based design and implementation of energy meter using iot and theft control concept. the distribution network operator can monitor the energy consumption in units from a web page by providing device such as smartphone. theft detection unit connected before energy meter will notify company side when meter tampering occurs in energy meter and it will send theft detect information through efficient applications and theft detected will be displayed on the terminal window on the service provider end. today's demand actually requires accessing the device characteristics remotely in a reliable way. one of the possible ways to accomplish the task is to connect a device (energy meter) to internet by providing efficiency to it. literature review the electricity provider company equally divides electricity bill on the only customer they have authority of electricity usage, but illegal customer are not involved in this bill. the entire electricity bill paid by the license customers, they are very less amount of customers. the electricity provider company not able to took an individual meter reading of farmer. they are equate the all the usage charge on the few customers only they have authority. the illegal customers are safe and getting continuous benefits without any compensation, but indirectly that electricity usage charge filled by license farmer. so, we decide to overcome that illegal usage of electricity by using smart technology that is iot. this system took continuous reading from the distribution system and upload on the web page through iot. at the other side that is customer meter side also taking continuous meter reading and upload on the web page. the difference of electricity reading between the distribution system and customer meter are continuously check by the web automatically. the minor error or electricity losses can be calculated but we are not considering here. there have various discussions done on how to detect and prevent the power theft. proposes a system design which incorporates an page - © mat journals . all rights reserved journal of optical communication electronics volume issue android application and also indicates the exact zone on which unauthorized taping is done in the real time when we using the gps and data base. proposed system energy is a necessary input in creation models along with capital, technology and labor and its sustainable supply at reasonable prices is estimated for a modern economy. it is therefore, a permanent constraint to output development. electricity shortfall effect economic development, causes joblessness, and increases the cost of manufacturing and doing increases farmer problems. various studies specify the relationship among agricultural growth and electricity consumption either through a demand-side model. to full fill the demand of electricity consumers we need to prevent illegal usage of the electricity. figure : block diagram of proposed system page - © mat journals . all rights reserved journal of optical communication electronics volume issue voltage divider circuit the incoming power supply is very high, it is approximately v. this amount of power we cannot calculate directly and cannot access through the microcontroller. a voltage divider circuit is a simple circuit which turns a large voltage into a smaller one. we can create an output that is a fraction of the input. the potential divider which takes advantages of the way voltage drop across resistors in used in our range of electricity fields. arm processor arm processor is a bit risc arm processor cores licensed by arm holding for microcontroller use. this device access a continuous reading from the voltage divider that voltage is minimum and measure it and transmit through the iot. this arm also provides input data to the lcd for displaying current power reading. it can handle multiple control action which is developer required. the incoming voltage is in the form of alternating current that is ac signal which cannot be directly measure. the one popular feature of arm processor is inbuilt adc which is convert this alternating current into binary that is called digital signal. this digital signal microcontroller can be access and measure. the measured digital value can be transfer to the web. distribution network operator access the data whenever they want through web or smartphone application. lcd the liquid crystal display is used to display the number. the lcd has pin which differentiate that pin for power control, pin for data pin, pin for read /write and pins for its brightness. the lcd took data from the microcontroller and display on it. whatever, the power variation made at the input which all the changes display on the lcd. primary module (at distribution side) the primary module placed at the side of electricity distribution system. it consist on the voltage divider ckt, arm processor, wi-fi module and lcd display. the voltage divider circuit provides low electric signal that can be access by the arm processor. the arm processor measure that ac signal by the help of inbuilt adc. the measured signal continuously uploading data to the web by the iot and also display on the lcd display. secondary module (at user side) the secondary module placed at the user side before meter. this module taking continuously reading coming from the distributed system i.e. coming from primary module. it provider measured electricity to the users. the measured amount of electricity displays on the lcd continuously. this is very beneficial for users because user can agree to how much electricity consume by the device. iot (internet of things) the internet of things is the network of devices such as electronics and connectivity which these things to connect, interact and exchange data. it involves extending internet connectivity beyond standard devices such as desktops, laptops smartphone and tablets. here we use web or smartphone for this application. the iot took continuously reading from both primary and secondary modules and store to the web or smartphone through the particular application. this application tolerates difference between these two modules. the difference between two modules should be equal. that means there is no power theft happened. it considers the minority power losses. when the difference between two modules become major that means power theft has been happened. how much amount of power theft by the peoples that can be observes by the distribution network operator through the iot technology page - © mat journals . all rights reserved journal of optical communication electronics volume issue advantages  it is very economical as compared to electricity losses.  individual power theft can be calculated.  does not affect the power transfer capability of the line.  it is very beneficial for farmer and also electricity provider company. applications  used in power distribution system.  we can use at the society if large amount of power theft is happen. future scope  we can use gps system to track exact location of power theft.  we can save a continuous data reading when we using data base.  we can use multiple secondary modules at every customer for better accuracy. conclusions it is the anti-theft detection system. even if theft is caught, the victim cannot get back his//her valuable belongings. that’s why it is clear that ‘prevention is better than cure’. by using this techniques crime of stealing power may be brought to an end and thereby a new bloom may be expected in the economy of our motherland and also there will be less scarcity for power utilisation. references . s.patil, g.pawaskar, k.patil., “electrical power theft detection and wireless meter reading”, international journal of innovative research in science, engineering and technology, vol. , issue , pp. – , april . g.l. prashanthi and k.v. prasad., “wireless power meter monitoring with power theft detection and intimation system using gsm and zigbee networks”, iosr journals of electronics and communication engineering(iosr - jece), vol. , issue , ver i,pp. – . . p.r. malhotra and r.seethalakshmi,“automatic meter reading and theft control system by using gsm”, international journal of engineering and technology(ijet),vol , no , pp. - , apr – may . how to understand mtrps induced human impairments and dysfunctions? copyright@ hui zhang | biomed j sci & tech res| bjstr. ms.id. . opinion issn: - how to understand mtrps induced human impairments and dysfunctions? qiang min huang and hui zhang* department of rehabilitation, hudong hospital, shanghai china *corresponding author: hui zhang, department of rehabilitation, hudong hospital, shanghai china doi: . /bjstr. . . received: march , published: march , article info abstract citation: qiang min huang, hui zhang. how to understand mtrps induced human im- pairments and dysfunctions?. biomed j sci & tech res ( )- . bjstr. ms.id. . opinion myofascial trigger point (mtrp) is a cytological lesion of skeletal muscle endplate. under light microscopy, mtrps’ muscle fiber shape shows morphological changes of deep-stained large round in cross section and bead-like in longitudinal section, company with muscle spindle compression [ ]. rare mitochondria were found under electron microscopy. in biochemical and microdialysis studies, there was a high concentration of acetylcholine at the neuromuscular junction. the contractile nodules were palpated, which observed under b-mode ultrasonography [ ]. the position of mtrps existed spontaneous electrical discharges. therefore, it is inferred that there may be an energy crisis at mtrps, which may locally exude neurogenic substances that stimulate nerve endings, and then introduced into the spinal cord through afferent nerve and to the pain center of the brain to sense local pain through the upstream channel. however, when this sensation is transmitted to the spinal cord, it results in sensitization of the spinal cord, resulting in a characteristic of referred pain and local twitch response (muscle juming) at mtrps. clinical observation shows that the referred pain has certain regularity, which is related to embryological development. in most cases, the closer to the mtrps in human midline, the referred pain is the same position of the affected muscle. however, the mtrps is far from human midline, the location of referred pain is often not in the affected muscle. therefore, clinicians often locate the mtrps according to the characteristics of referred pain in each muscle [ ]. this is the fastest way to locate the mtrps for acupuncture, and then confirm the accuracy of mtrps in local twitch response (jumping) by needling. most clinicians believe that induced jump is very important often with a good effect, but it is not very necessary depending on the experience of a clinician. with the development of mtrps knowledge, the accumulation of clinical experience and the expansion of treatment scope, many clinicians have found that the treatment of pain, only from the occurrence of mtrps, can only treat the simple fascia pain caused by the activity mtrps, while the functional impairment of various parts of the human body, caused by the long-term multiple latent mtrps, appears to be inadequate. therefore, it is necessary to consider how the mtrps can cause human dysfunction in different parts of the body. here the following figure explains its possible pathogenesis figure shows that pathological factors that originate from primary mtrps cause a disturbance of lever, fascia or ligament mechanics and coelomic capsular system and secondary mtrps, leading to disorders of some part of the body or viscera [ ]. therefore, any treatment aimed at disorder adjustment is usually prone to recurrence or incomplete treatment if the source problem is not eliminated [ - ]. this kind of thinking suggests that when a clinician adjusts the lever and the fascial imbalance mechanics and the disturbance of the coelomic capsular system, he should also consider the primary mtrps at the source of treatment, so as to cure the patient’s disease better. https://biomedres.us/ http://dx.doi.org/ . /bjstr. . . copyright@ hui zhang | biomed j sci & tech res| bjstr. ms.id. . volume - issue doi: . /bjstr. . . figure : the diagram of various disorders and impairments which relate to mtrps. submission link: https://biomedres.us/submit-manuscript.php assets of publishing with us • global archiving of articles • immediate, unrestricted online access • rigorous peer review process • authors retain copyrights • unique doi for all articles https://biomedres.us/ this work is licensed under creative commons attribution . license issn: - doi: . /bjstr. . . hui zhang. biomed j sci & tech res references . huang qm, ye g, zhao zy, lv jj, tang l ( ) myoelectrical activity and muscle morphology in a rat model of myofascial trigger points induced by blunt trauma to the vastus medialis. acupunct med ( ): - . . huang qm, lv jj, ruanshi qm, liu l ( ) spontaneous electrical activities at myofascial trigger points at different stages of recovery from injury in a rat model. acupunct med ( ): - . . liu qg, liu l, huang qm, nguyen tt, ma yt, et al. ( ) decreased spontaneous electrical activity and acetylcholine at myofascial trigger spots after dry needling treatment: a pilot study. evid based complement alternat med. . zhang h, lü jj, huang qm, liu l, liu qg, et al. ( ) histopathological nature of myofascial trigger points at different stages of recovery from injury in a rat model. acupunct med ( ): - . . zhuang x, tan s, huang q ( ) understanding of myofascial trigger points. chin med j ( ): - . . huang qm, zhang yd, ma yt ( ) understanding of myofascial trigger points: debates between acupuncture and dry needling (chinese). chin acupunct ( ): . http://dx.doi.org/ . /bjstr. . . https://biomedres.us/submit-manuscript.php https://biomedres.us/ http://dx.doi.org/ . /bjstr. . . https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ https://www.ncbi.nlm.nih.gov/pubmed/ http://austinpublishinggroup.com/physical-medicine/fulltext/pmr-v -id .php http://austinpublishinggroup.com/physical-medicine/fulltext/pmr-v -id .php http://austinpublishinggroup.com/physical-medicine/fulltext/pmr-v -id .php 	how to understand mtrps induced human impairments and dysfunctions? 	opinion 	references 	figure experimental study of a novel pv/t- air composite heat pump hot water system energy procedia ( ) – available online at www.sciencedirect.com sciencedirect - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review by the scientific conference committee of shc under responsibility of pse ag doi: . /j.egypro. . . international conference on solar heating and cooling for buildings and industry, shc experimental study of a novel pv/t- air composite heat pump hot water system gang wanga, zhenhua quana, * , yaohua zhaoa, peng xua , chenming suna athe department of building environment and facility engineering, the college of architecture and civil engineering, beijing university of technology, no. pingleyuan, chaoyang district, beijing , china abstract solar energy utilization and heat pump are common technologies of renewable energy utilization for solving the problem of energy crisis and environmental pollution in present. this paper proposed a novel pv/t-air composite heat pump hot water system. the system was comprised of independently developed flat plate solar pv/t collector based on micro-channel heat pipe array and air source heat pump, which were combined by a new composite evaporator. the performance of the system were experimentally studied cop of heat pump reduced from . to . and the average was . . comprehensive copsys of pv/t-air composite heat pump system ranged from . to . , the average was . . the result showed the system was worthy of promotion and application. © the authors. published by elsevier ltd. peer-review by the scientific conference committee of shc under responsibility of pse ag. keywords: pv/t collector, air source heat pump, composite evaporate , coefficient of performance (cop) . introduction the joint operation of solar energy and heat pump is a significance technology, which can address the problem of energy crisis and environmental pollution. in recent years, domestic and foreign scholars have done a lot of research on solar-assisted heat pump (sahp) heating system to improve energy efficiency of the system. the system of sahp can be sub classified as series, parallel and dual system according to the heat source to the evaporator. though variety of different binding modes among solar collector and heat pump were possible and studied, the main * corresponding author. tel.: + ; fax: + - . e-mail address: quanzh@ .com © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review by the scientific conference committee of shc under responsibility of pse ag http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf gang wang et al. / energy procedia ( ) – research focuses were on the combination of solar collector and air source heat pump or water source heat pump [ - ]. hawlader at el. [ ] designed and fabricated a sahp system, the drying medium was air. the coefficient of performance and solar fraction used as the main evaluation indicators of system performance were . and . derived from experimental results, and were . and . from simulation results, respectively. fu at el. [ ] presented a technology of combing heat pump with heat-pipe photovoltaic/thermal (pv/t) collector, the performances of heat pipe mode, solar assisted heat pump and air-source heat pump mode were investigated in that paper, and concluded ultimately that the system could satisfy the demand of domestic hot water with or without solar energy. this paper designed a novel pv/t-air composite heat pump hot water system. it comprised of independently developed solar photovoltaic-thermal (pv/t) collector and composite heat source heat pump. this system can not only obtain electric power, but also effectively use the solar battery waste heat through the heat pump, which makes the system energy utilization efficiency is improved greatly. and the performance of the system can be guaranteed, supplemented by air source heat pump. . experimental setup of pv/t-air composite heat pump hot water system pv/t-air composite heat pump hot water system is comprised of the solar pv/t system, composite heat pump system and the system of heat utilization, as shown in fig. . the core component of solar system is pv/t collector based on flat plate micro heat pipe and composite evaporator, which combined air source and pv/t water source. low temperature hot water is generated by pv/t collector, which effectively utilizes the waste heat of pv modules and decreases the temperature of the battery temperature to improve the power generation. the low temperature hot water flows through the composite evaporator and heat transfer to the refrigerant. after that cooled water flows back into the pv/t collectors to start the next cycle. thus, the backboard of the pv/t collector can maintain a relatively low temperature, the efficiency of photovoltaic power generation is improved and the battery life is prolonged. meanwhile, low temperature hot water into pv/t collector increases the evaporation temperature of composite heat evaporator, which can solve the problem of air source heat pump anti-frost in cold regions and improve the performance of heat pump system. this technology will expand the scope of application of air source heat pump. the drawing of pv/t collector is showed as fig. . the new type of pv/t collector is fabricated on the basis of photovoltaic cell, whose backboard is affixed to flat plate micro-channel heat pipe array. fig. diagram of pv/t-air composite heat pump system gang wang et al. / energy procedia ( ) – the composite evaporator is designed on the basis of finned - tube evaporator, as shown in figure . the channel and channel are loop of solar photovoltaic water and loop of working refrigerant, respectively. a number of heat exchange fins are connected in order between the two channels. air flows through the gap of the fins. . experimental test . experimental description the experimental platform of pv/t-air composite heat pump system was established, as fig. . the experimental plan was designed to study the performance of the system for solar heat collecting operating mode firstly and then air source heat pump operating meanwhile. the pv/t system had two pieces of collectors, whose type is csun- - m and peak power is w. the circulating flow of collecting tank and heating tank are l/h and l/h, respectively. the power of collecting water pump and heating water pump are w and w, respectively. the volume of heating tank and collecting tank are l and l, respectively. water in the heating tank was heated by hp heat pump, water temperature of initial and termination in the heating tank were . and . , respectively. the pv/t system began to operate from : to : , air source heat pump operated at : without opening the fan, when water temperature in the collecting tank decreased certain value, then opening the fan at : . the main researched performances of the system included photovoltaic power and thermal power of pv/t collector, photovoltaic efficiency, and thermal efficiency. and, cop of composite heat pump and copsys of composite heat pump were also evaluated. fig. the component drawing of pv/t base on micro heat pipe array fig. schematic diagram of evaporator gang wang et al. / energy procedia ( ) – . instantaneous efficiency of system coefficient of performance is an important target of heat pump, which is defined as , ,( ) ( ) w w w t w t hp t hpt c m t t cop w d ( ) where whp( ) is the power consumption of compressor, kw; cw is the heat capacity of water, kj /(kg·k); mw is the capacity of heating tank, kg; tw,t+ is the initial temperature of heating tank, ; tw, t + is the termination temperature of the heating tank, . copsys is a major evaluation indicator of the system performance, which is defined as where copsys is the overall performance of system; qt is heat gain in the heating tank; wp is the compressor power, w; we is the photovoltaic power generation, w. . experimental results and analysis fig. shows that the ambient temperature and solar irradiance changes with time. the ambient temperature ranged from to . , the solar irradiance changed from w/m to w/m . fig. experimental platform of pv/t-air composite heat pump system ep t sys ww q cop ( ) gang wang et al. / energy procedia ( ) – fig. shows photovoltaic power and photovoltaic efficiency changes with time. the maximum power was w when the system operated from : to : , and the maximum photovoltaic efficiency was . %, which had obvious advantages compared to separate solar pv collector. shadow has a large impact for the photovoltaic efficiency, thus, the figure appeared the phenomenon of depressing because of the shade shelter. fig. shows thermal power and thermal efficiency changing with time. thermal power was calculated by test the instantaneous inlet and outlet water temperature of solar pv/t collector. thermal power and thermal efficiency presented the parabolic trend. the maximum thermal power was w and the minimum was w. the changing of thermal efficiency in the collecting tank was relatively stable and ranges in . %- . %. fig. shows cop of heat pump and copsys of system changing with time. the compressor power was gradually increasing so that the cop of heat pump gradually decreased. the maximum cop was . and the minimum was . , the average was . . the copsys of system ranged from . to . and the average was . , and the changing trend basically was consistent with heat pump cop. the curve of copsys sagged in the operation for the reason that the fan opened at this point. fig. solar irradiance and ambient changing with time fig. photovoltaic power and photovoltaic efficiency changing with time gang wang et al. / energy procedia ( ) – . conclusions the novel pv/t-air composite heat pump hot water system was experimentally studied and the experimental results were discussed and analysed. the maximum photovoltaic power and the instantaneous efficiency were w and . %, respectively. the changing range of thermal power and thermal efficiency were w- w and . %- . %. cop of heat pump reduced from . to . and the average was . . comprehensive copsys of pv/t-air composite heat pump system ranged from . to . , the average was . . and copsys is a major evaluation indicator of the heat pump system performance. we can see from the results analysis, compared with single air source heat pump, the pv/t-air composite heat pump hot water system has some advantages and is worthy of promotion and application. fig. thermal power and thermal efficiency changing with time fig. cop and copsys changing with time gang wang et al. / energy procedia ( ) – acknowledgement the project was financially supported by the natural science foundation of beijing (grant no. z ) and the national science & technology pillar program during the twelfth five-year plan period (grant no. baa b ). the authors are grateful for the support of these sponsors. references [ ] liang c.h zhang x.s zhu x, li x.w. performance analysis of heat pump based on a new solar air-source heat pump heating system [j]. journal of southeast university. ( ): - . [ ] luo h.l tie y li m zhong h. thermal performance study on a solar energy water heating system in conjunction with air-source heat pump [j]. building science. ( ): - . [ ] zhang h.j study on solar energy/air-source heat pump compound system [j]. guangxi journal of light industry. ( ): - . [ ] m.n.a. hawlader, s.k. chou, k.a. jahangeer, s.m.a. rahman, k.w. eugene lau, solar-assisted heat-pump dryer and water heater, appl. energy ( ) - . [ ] h.d. fu, g. pei, j. ji, h. long, t. zhang, t.t. chow. experimental study of a photovoltaic solar-assisted heat-pump/heat-pipe system, thermal engineering ( ) - . [ ] zhao y.h wang h.y diao y.h wang x.y, deng y.c. heat transfer characteristics of flat micro-heat pipe array [j]. journal of chemical industry and engineering. ( ): - . energy crisis: the role of oxidative phosphorylation in acute inflammation and sepsis biochimica et biophysica acta ( ) – contents lists available at sciencedirect biochimica et biophysica acta journal homepage: www.elsevier.com/locate/bbadis review energy crisis: the role of oxidative phosphorylation in acute inflammation and sepsis icksoo lee a, maik hüttemann b,c,d,e,⁎ a college of medicine, dankook university, cheonan-si, chungcheongnam-do - , republic of korea b center for molecular medicine and genetics, wayne state university, detroit, mi , usa c cardiovascular research institute, wayne state university, detroit, mi , usa d department of biochemistry and molecular biology, wayne state university, detroit, mi , usa e karmanos cancer institute, detroit, mi , usa abbreviations: cytc, cytochrome c; cox, cytochrome c chain; icu, intensive care units; jnk, jun n-terminal ki mtdna, mitochondrial dna; mods, multiple organ dysfu dative phosphorylation; pp a, protein phosphatase a; tlr , toll-like receptor ; tnfα, tumor necrosis factor alp ⁎ corresponding author at: center for molecular medi university, scott hall, e. canfield, detroit, mi e-mail address: mhuttema@med.wayne.edu (m. hütte http://dx.doi.org/ . /j.bbadis. . . - /© published by elsevier b.v. a b s t r a c t a r t i c l e i n f o article history: received january received in revised form april accepted may available online june keywords: cytochrome c oxidase electron transport chain haplogroup inflammation mitochondria reactive oxygen species mitochondrial dysfunction is increasingly recognized as an accomplice in most of the common human diseases including cancer, neurodegeneration, diabetes, ischemia/reperfusion injury as seen in myocardial infarction and stroke, and sepsis. inflammatory conditions, both acute and chronic, have recently been shown to affect mitochondrial function. we here discuss the role of oxidative phosphorylation (oxphos), focusing on acute inflammatory conditions, in particular sepsis and experimental sepsis models. we discuss mitochondrial alter- ations, specifically the suppression of oxidative metabolism and the role of mitochondrial reactive oxygen species in disease pathology. several signaling pathways including metabolic, proliferative, and cytokine signaling affect mitochondrial function and appear to be important in inflammatory disease conditions. cytochrome c oxidase (cox) and cytochrome c, the latter of which plays a central role in apoptosis in addition to mitochondrial respi- ration, serve as examples for the entire oxphos system since they have been studied in more detail with respect to cell signaling. we propose a model in which inflammatory signaling leads to changes in the phosphorylation state of mitochondrial proteins, including tyr phosphorylation of cox catalytic subunit i. this results in an in- hibition of oxphos, a reduction of the mitochondrial membrane potential, and consequently a lack of energy, which can cause organ failure and death as seen in septic patients. © published by elsevier b.v. . introduction sepsis is an acute systemic condition that is sometimes referred to as blood poisoning in the non-medical literature, but whose definition has changed to reflect the inflammatory response of the body, including the development of multiple organ dysfunction syndrome (mods) [ ]. about % of all patients in intensive care units (icus) have severe sep- sis [ ] with a higher incidence in blacks than in whites [ ]. this life- threatening condition develops in a million people annually in the united states with more than , deaths, making it the leading cause of mortality in icu patients [ ]. apparently, the combination of a pathogenic infection with a maladaptive immune response can cause oxidase; etc, electron transport nase; lps, lipopolysaccharide; nction syndrome; oxphos, oxi- ros, reactive oxygen species; ha cine and genetics, wayne state , usa. tel.: + . mann). organ dysfunction and eventual death. a major hurdle is the lack of markers that allow early diagnosis and that can predict outcome. a re- cent review of the literature reports biomarkers including microbi- ological cultures to identify the pathogen, and markers of inflammation such as c-reactive protein and procalcitonin analyzed from blood [ ]. in the future, panels of markers will likely be used to increase sensitivity and specificity, such as multiplexed quantitative pcr [ ], which can be easily employed with a fast readout. a possible explanation for the lack of robust markers is the inherent problem of defining sepsis due to the large heterogeneity of the patient population that presents with acute infection. sepsis can originate from any site in the body in combination with unspecific responses such as tachycardia and tachypnea all the way to organ dysfunction and failure [ ]. severe sepsis is characterized by acute organ dysfunction, which can develop during the course of an overwhelming infection, and septic shock is severe sepsis in combination with a dangerous drop in systolic blood pressure [ ]. sepsis is mostly caused by bacterial infections in ad- dition to fungal infections originating at various sites in the body. given the large heterogeneity of sepsis including the different stages, special care is needed when experimental data are interpreted and studies are compared. http://crossmark.crossref.org/dialog/?doi= . /j.bbadis. . . &domain=pdf http://dx.doi.org/ . /j.bbadis. . . mailto:mhuttema@med.wayne.edu http://dx.doi.org/ . /j.bbadis. . . http://www.sciencedirect.com/science/journal/ i. lee, m. hüttemann / biochimica et biophysica acta ( ) – to study acute inflammation in animals several models are com- monly used, such as i.v. and i.p. injections of lps (lipopolysaccharide, endotoxin), fecal peritonitis including cecal ligation and puncture (clp), and injection of live bacteria. most studies are performed in rats and mice but other animals are commonly used too, such as pigs. it should be noted that animal models used by researchers have certain limitations and sometimes only reflect certain aspects of the condition. for example, researchers often administer large doses of bacteria or en- dotoxin as a single bolus, whereas in patients there is a gradual increase in pathogen load over time. therefore, a bolus administration of bacteria or endotoxin to a healthy animal has no clinical correlate [ ]. the latter models produce a profound and fast hypodynamic response, a decrease in cardiovascular function and cardiac output leading to death within hours, whereas septic patients show a hyperdynamic response [ ]. if lower amounts of endotoxin are administered a short hyperdynamic response can be seen followed by the hypodynamic response [ ]. the fecal peritonitis model including the clp model may better reflect human sepsis due to the temporal worsening along with an extended hyperdynamic cardiovascular response [ ]. differences between models such as bolus administration of lps or bacteria versus fecal peritonitis may at least in part explain some data in the literature which at first sight seem to be conflicting. in addition, experimental shortcomings to realistically reflect sepsis may explain why there has been relatively lit- tle success in the past in translating promising findings from preclinical animal studies into the clinic [ ]. these experimental limitations have to be taken into consideration at the planning stage of preclinical studies and when comparing experimental results using different models. . role of oxidative phosphorylation in acute inflammation several lines of evidence, genetic and functional, suggest that the mi- tochondrial oxphos system is a primary site of action during acute in- flammation and that it is a central determinant of clinical outcome. inflammatory responses are key for the outcome of sepsis and may af- fect cellular function at a very basic level, i.e., the mitochondrial oxphos system, whose role in sepsis is still somewhat controversial. most stud- ies we are aware of reported decreased atp levels in animal models of sepsis and in human patients [ – ]. for example, a human compara- tive study found that the average atp/adp ratio in muscle tissue was . in septic survivors versus . in non-survivors [ ]. using a rat fecal peritonitis model, the same group later reported a drop of atp and an increase in amp levels in skeletal muscle and liver tissues starting at h and h in liver and muscle tissues, respectively [ ]. applying a single bolus of lps, the kozlov lab reported a % reduction in liver atp levels after h which improved at later time points in surviving animals [ ]. however, there are some reports that found no changes in cellular energy levels [ – ], likely because oxphos was still able to support cellular function at the time of measurement or because overall metabolism and energy utilization are reduced [ ]. even if changes in cellular energy levels were not detected in the afore- mentioned studies, metabolic changes did occur including increased lactate production [ , ], suggesting that increased glycolytic flux can maintain cellular energetics at least for some time. in addition to differences between animal models and their ability to reflect sepsis as discussed in the previous section, bioenergetic discrep- ancies between some of the published reports may also be explained, at least in part, by the utilization of assay protocols that do not preserve posttranslational modifications, since almost all older protocols for mi- tochondria isolation or mitochondrial assays do not utilize phosphatase inhibitor cocktails. we have thus modified existing protocols to main- tain the physiological phosphorylation state of mitochondrial proteins and described the methods in detail for cox [ ] and cytc [ ], which has allowed us to map and study over phosphorylation sites on the two proteins in different animals and tissues [ – ]. such mod- ifications, in particular cytokine-mediated phosphorylations in the con- text of sepsis, may be easily lost when enzymes, i.e., phosphatases, that reverse such modifications are not inhibited. therefore, most studies that involve mitochondria isolation followed by mitochondrial activity measurements have to be interpreted in light of the possible event that protein phosphorylations and perhaps other posttranslational modifica- tions have been lost. . . the energy metabolism crisis model a recent study conducted by kingsmore and colleagues analyzed the plasma metabolome (i.e., the composition of metabolites such as amino acids, krebs cycle intermediates, and acyl-carnitines) and proteome (i.e., the protein complement expressed in cells, tissues, or bodily fluids) of sepsis survivors and non-survivors [ ]. the study revealed several interesting findings. first, survivors of sepsis, severe sepsis, and septic shock showed no prominent differences in their metabolome and proteome. second, there were no major differences among patients infected with three different pathogens, streptococcus pneumoniae, staphylococcus aureus, or escherichia coli. in contrast, there were sig- nificant differences between sepsis survivors and non-survivors. for example, nine proteins involved in fatty acid transport were de- creased in sepsis non-survivors suggesting a defect in β-oxidation. the non-uptake and non-utilization of fatty acids by the mitochon- dria led to an accumulation of acyl-carnitines in the plasma, another predictive marker for outcome established by the study. glycolysis and gluconeogenesis were also markedly different. sepsis survivors showed decreased levels of citrate, malate, glycerol, glycerol -phosphate, phos- phate, and glucogenic and ketogenic amino acids whereas non-survivors showed increased levels of citrate, malate, pyruvate, dihydroxyacetone, lactate, phosphate, and gluconeogenic amino acids [ ]. this data sug- gests that non-survivors cannot effectively utilize common metabolites to generate energy through the aerobic mitochondrial pathway. another study reported that mitochondria are dysfunctional in human skeletal muscle of septic patients, but this effect is not due to altered mitochon- drial biogenesis since in vivo protein synthesis and expression of mito- chondrial genes is indistinguishable from controls [ ]. these studies demonstrate that cellular metabolism is altered and affects several met- abolic pathways in sepsis and suggest that metabolic enzyme levels might not be the culprit. in this article, we put forth the proposal that in- flammatory signaling suppresses the activity of key metabolic enzymes leading to metabolic dysfunction. we propose that an important functional target of inflammatory sig- naling is the mitochondrial oxphos machinery. it has long been known that direct systemic delivery of oxygen during the course of sepsis does not improve disease outcome in septic patients [ ]. rats subjected to clp had muscle tissue oxygen levels similar to the sham control and septic animals after h, but the septic animals had significantly ( %) reduced atp levels [ ]. this suggests that oxygen utilization but not delivery is impaired, a condition referred to as cytopathic hypoxia [ ]. this may further suggest that cox as the terminal acceptor of oxygen might be functionally different during the course of sepsis. in this and the following sections, we develop a model (fig. ), in which in- flammatory signaling leads to the inhibition of cox via tyrosine phos- phorylation followed by the depolarization of the mitochondrial membrane potential, impaired atp production and finally energy failure. together with the other oxphos complexes, the reaction catalyzed by cox and cytc generates energy to drive all cellular functions. in addition, cytc regulates cellular survival and executes apoptosis. it is thus not surprising that both cox and cytc have been implicated in the pathology of sepsis. in a recent editorial, dolganiuc concludes that “how and why excessive cox inhibition becomes detrimental and limits the survival during sepsis may be among the top research priorities of this area” [ ]. a preliminary answer to this question may already be at hand, via the phosphorylation of cox, as we will discuss at the end of this section. tk fig. . proposed sequence leading to mitochondrial dysfunction and energy crisis during acute inflammation. pathogen associated molecules such as lps are recognized by toll- like receptors triggering inflammatory responses including the production of tnfα. tnfα leads to the activation of an unknown downstream tyrosine kinase (tk) that phos- phorylates cox on tyr leading to strong enzyme inhibition, a critical reduction in the mitochondrial membrane potential ΔΨm, and a drop in energy levels in target organs that can lead organ failure and death (black arrows). it remains to be shown if toll-like receptor signaling can directly activate the downstream tk and if there are oxphos complexes other than cox that are also targeted for phosphorylation (green arrows). i. lee, m. hüttemann / biochimica et biophysica acta ( ) – . . genetic evidence: nuclear polymorphisms and the mitochondrial haplogroup as predictive markers a small number of non-mitochondrial genetic markers for the out- come of sepsis have been proposed. a polymorphism ( c) identi- fied in the gene of toll-like receptor (tlr ), which is important for the activation of the innate immune response and recognizes lps, was associated with a better prognosis [ ], likely due to a decreased immune response including lower levels of cytokines such as tnfα. the same concept is supported by another study showing that a polymorphism in the tnfα gene, which results in higher circulating tnfα concentrations, is associated with higher rates of mods [ ]. other examples with various levels of predictive power are polymor- phic variants in the ′-utr of the human leukocyte antigen g (hla-g) gene [ ], polymorphisms in the leptin and leptin receptor genes [ ], a polymorphism in the promoter of the macrophage migration inhibito- ry factor (mif) gene [ ], the t/c polymorphism of tissue inhibitor of matrix metalloproteinase (timp)- in which the t allele was associated with % higher mortality [ ], and the c/t polymorphism in the interleukin- -receptor-associated kinase (irak ), which was associat- ed with the need for prolonged mechanical ventilation and decreased survival [ ]. these genetic markers suggest that a dysregulation of the immune response, specifically an overactivation, is associated with de- creased survival. interestingly, the composition of mitochondrial dna, the so-called haplogroups have also been suggested as predictors of survival after sepsis. mitochondrial haplogroups are defined by a relatively small number of mitochondrial dna polymorphisms that are preserved in various populations, and these subtle changes have been associated with certain phenotypes, such as longevity, male fertility, cardiomyopa- thy, and neurodegenerative diseases [ – ]. a study conducted in england revealed that europeans who are haplogroup h carriers have a more than twofold increased chance of survival after sepsis compared to patients with other haplotypes [ ]. thus, mitochondrial haplogroups may behave as susceptibility factors for the outcome of certain diseases including sepsis. another recent study conducted in spain showed that the jt haplotype is also associated with higher sur- vival rates and that patients with this haplotype have on average a % higher cox activity and % increased cox protein levels normal- ized to citrate synthase activity in platelets at the time of diagnosis [ ]. at days and after diagnosis, average cox amount was statisti- cally significantly increased ( % and %, respectively). the authors suggested that while cox levels in platelets and thus platelet function is unlikely to be a factor determining survival, it might reflect differ- ences in mitochondrial function in other tissues and organs [ ]. it is not fully clear at this point what functional and mechanistic effects dif- ferent haplogroups have and how they relate to improved survival. however, there are studies that have concluded that there are changes in mitochondrial function depending on the haplogroup. for example, using cybrid methodology, which allows studying mitochondria derived from different haplogroups in the same cellular (i.e., nuclear dna) background, gomez-duran and colleagues showed increased mitochondrial membrane potential and cytochrome c oxidase (cox) activity in h versus uk haplogroup mitochondria [ ]. it is therefore possible that cox activity and amount could serve as a predictive blood-based marker for the outcome of sepsis. recent studies in c bl/ and c h/hen mice strains and strains generated by replacing the endogenous mitochondria with the mitochondria of the other strain indicated that the mitochondrial haplogroup determines state respira- tion rates of isolated cardiac mitochondria as well as basal membrane potential and ros levels [ ]. it is unclear, however, how important ros are as a determinant of outcome after acute inflammation versus atp, as discussed in section . . . oxidative phosphorylation - temporal changes during acute inflammation acute inflammation causes both short-term and longer-term effects and adaptations at the level of oxphos. crouser and colleagues observed a % reduction of cox activity in cats h after lps administration in combination with partial uncoupling of mitochondrial oxphos [ ]. another study found that electron transport chain (etc) complexes i, ii, and cox were down-regulated in the diaphragm within h after lps administration in rats, both at the mrna and protein level, and state respiration declined by % [ ]. proteomic analysis of cat liver mitochondria h after lps administration revealed proteins that showed differences in protein levels. among them was one oxphos member, atp synthase α subunit, which was % reduced in the septic animals [ ]. early during septic shock using the clp model, rat liver mi- tochondria showed significantly reduced mitochondrial respiration rates and reduced cox levels [ ]. interestingly, lu and colleagues observed significantly increased and decreased mitochondrial atp synthase activity in rats after applying mg/kg lps at the early and late stages of endotoxic shock, respectively [ ]. these findings may be explained by the temporal development in this model, with a hyperdynamic followed by a hypodynamic response, utilizing a rela- tively low lps bolus. at the level of cox, early in sepsis after clp, the ox- idation of cytc by cox was competitively and reversibly inhibited in the hearts of mice, whereas at a later time point ( h), it became noncom- petitive and irreversible [ ]. at that time point animals with fulminant sepsis showed about % reduced vmax of cox measured spectrophoto- metrically. after lps injection rats showed a time-dependent increase of cytc in the cytosolic fractions in the heart along with increased apopto- tic markers [ , ], suggesting that cytc release from the mitochondria and the execution of apoptosis become more prevalent in the late stage of sepsis in the animal model. in the brain of septic rats after clp, certain cell types, such as the hippocampal ca region, the choroid plexus, and purkinje cells of the cerebellum, showed increased susceptibility levels to the induction of apoptosis [ ]. the authors found that among the ap- optotic markers tested, cytc release was the only one with prognostic power. it is important to note, however, that the finding of increased i. lee, m. hüttemann / biochimica et biophysica acta ( ) – apoptosis as observed in several animal studies might be a shortcoming of the models, since apoptosis does not seem to be the key determinant in patients with sepsis. in contrast to organs such as the heart or brain shown to be affected in the animal models, only a few cell types includ- ing lymphocytes and gastrointestinal epithelial cells die through an apoptotic process in septic patients [ ]. in lymphocytes, the release of cytc from the mitochondria would trigger apoptosis and also augment oxphos dysfunction due to the interruption of electron flux in the etc. this may contribute to a failure of the immune system since the preven- tion of lymphocyte apoptosis was shown to improve survival [ ]. inter- estingly, the levy group was able to restore mitochondrial respiration in the hearts of mice subjected to cecal ligation and puncture by i.v.-injec- tion of cow heart cytc [ , ], apparently without triggering apoptosis. the treatment led to an uptake of cytc into the cardiomyocytes, and sur- vival increased from % for the sepsis control group to about % in mice that were also injected with cytc. the uptake might be facilitated by an interesting feature of cytc; it contains a cell-penetrating peptide sequence located in the c-terminus of the protein [ ], enabling it to cross cellular membranes in a non-traditional fashion. taken together, these studies suggest that mitochondrial dysfunc- tion via a decrease of oxphos function and an increase in apoptotic ac- tivity in selected cell types may contribute to the septic phenotype. the role of inflammatory signaling discussed below and temporal changes thereof may be important to understand the different phases during the course of sepsis and the point of no return when mitochon- drial failure cannot be reversed any longer, leading to death. . . tyrosine phosphorylation on cytochrome c oxidase subunit i as a metabolic switch to strongly inhibit oxphos in acute inflammation lps administration in experimental sepsis leads to a tlr -mediated burst of pro-inflammatory cytokines, including tumor necrosis factor α (tnfα). in a rat model of endotoxic shock tnfα expression peaked early after lps injection and led to a % decrease in cellular atp levels [ ] (fig. ). in septic patients plasma levels of tnfα were significantly higher in patients that died compared to the surviving group [ ], making tnfα an interesting target for therapy. neutralizing it with an antibody fragment against tnfα in experimental sepsis resulted in sig- nificantly increased survival rates [ ]. however, a similar treatment only slightly improved survival in patients with sepsis [ ], suggesting that there is redundancy in inflammatory signaling. nevertheless, tnfα alone is sufficient to induce metabolic changes similar to those seen in sepsis. for example, tnfα induces the generation of lactate in vitro and in vivo [ , ], pointing to an impairment of aerobic energy metabolism. in order to investigate the effect of inflammatory signaling at a more mechanistic level we analyzed the effect of tnfα on liver tissue from cow and mouse as well as mouse hepatocytes in culture. tnfα treat- ment of liver tissue homogenates resulted in a fast (within min) % reduction of cox activity [ ]. purification of cow cox after tnfα treat- ment, using protocols that preserve phosphorylations, following western analysis suggested tyrosine phosphorylation on catalytic subunit i. further analysis with a phospho-epitope-specific antibody re- vealed the phosphorylation of tyrosine , the same site that we earlier mapped by mass spectrometry after activating the camp-dependent pathway in the liver [ ]. in cultured mouse h . hepatocytes tnfα treatment for min had a profound diminishing effect on the mitochon- drial membrane potential and resulted in a % reduction of cellular atp levels [ ] (fig. ). tyr is located on helix viii of catalytic subunit i, close to the intermembrane space (fig. ). helix viii is in contact with the heme a –cub reaction center where oxygen is reduced to water (fig. , right), an ideal site for cox regulation. tyr and the surround- ing epitope are highly conserved in eukaryotes [ ]. interestingly, the cox substrate cytc has a similar epitope surrounding tyr with out of amino acids being identical and this site is phosphorylated in heart tissue under normal conditions, although it is unclear to what extent [ ]. because cytc tyr phosphorylation leads to a shift of the km of cox for cytc from . μm for dephosphorylated cytc to . μm for phosphorylated cytc, and because the epitopes in cox and cytc are similar, tnfα-mediated phosphorylation of cytc would augment the effect of cox tyr phosphorylation, a concept that we will ex- plore in future work. it should be noted that oxphos components other than cox (and perhaps cytc) may also be affected in a similar way by posttranslational modifications. for example, decreased activity has been reported in sev- eral animal sepsis models as well as in patients for one or more of the other etc complexes [ , , – ], but the molecular mechanism still has to be elucidated. over phosphorylation sites have been mapped on oxphos complexes but for almost all of them the functional effects and the signaling pathways involved, including kinases and phospha- tases, remain unknown (reviewed in [ ]). other proposals to explain reduced oxphos activity exist. for exam- ple, one study reported selective degradation of some subunits of the oxphos complexes i, iii, iv, and v in the diaphragm after experimental sepsis using d blue native gel electrophoresis [ ]. however, the authors also reported the strong upregulation of cox subunit iv. given the usually assumed : stoichiometry of the oxphos subunits, additional follow-up experiments including direct western blotting after d sds page would be needed to strengthen or disprove such a model. later, using the same experimental approach, the authors reported the downregulation of all oxphos subunits analyzed h after lps administration [ ]. more recently and in agreement with the model put forth in this review, the authors favored a mechanism involving cell signaling and identified p mitogen activated protein ki- nase and double-stranded rna-dependent protein kinase as kinases that determine the extent of the execution of apoptosis [ , ]. they also showed that the stress enzyme jun n-terminal kinase (jnk) was activated in the lps sepsis model of diaphragmatic dysfunction, and that its pharmacologic inhibition prevented caspase activation and di- aphragm weakness in septic mice [ ]. under conditions of stress, activated jnk translocates to the mitochondria, inhibits mitochondrial respiration, and can induce apoptosis via a permeability transition pore dependent or independent mechanism, resulting in the release of proapoptotic factors from the mitochondria such as cytc [ , ]. as expected, the suppression of jnk translocation to the mitochondria pro- tects mitochondrial integrity and function [ ]. it was shown that jnk translocates to the mitochondrial outer membrane where it phosphor- ylates pyruvate dehydrogenase, leading to enzyme inhibition and thus limited substrate delivery for the krebs cycle and oxphos [ ]. it is possible that jnk activates other kinases within the mitochondria, such as the as-of-yet unknown tyrosine kinase that phosphorylates cox subunit i tyr (fig. ). in addition to kinases that act on mitochondrial enzymes, protein phosphatases are equally interesting therapeutic targets. for example, in a rat sepsis heart failure model it was shown that lps administration leads to protein phosphatase a activation and a concomitant reduction of mitochondrial calcium retention capacity [ ]. pp a is an interesting phosphatase candidate to dephosphorylate and thus regulate mito- chondrial proteins because it localizes to the mitochondria in many tissues, including the heart and brain [ ]. pp a is a multifunctional heterotrimeric serine/threonine protein phosphatase composed of a scaffolding a subunit, a catalytic c subunit, and a regulatory b subunit, the latter of which is expressed as several distinct isoforms. for exam- ple, among b subunit isoforms, the brain-specific splice isoform bβ , upon neurotoxic stress, translocates from the cytosol to the outer mitochondrial membrane, triggered by the phosphorylation of three n-terminal residues [ ], to induce mitochondrial fission and to execute apoptosis [ ], a process which is accompanied by increased ros pro- duction [ ]. mitochondrial pp a also provides a direct link to autoph- agy, which is induced in several disorders including neurodegenerative disease due to mitochondrial dysfunction or cellular stress and can fur- ther enhance cellular demise [ ]. the protein may also localize to the fig. . tnfα leads to the phosphorylation of tyr of cox catalytic subunit i. crystal structure data of cow heart cox [ ] were used and processed with the program swiss-pdbviewer . . left, overview of cox with catalytic subunits i and ii highlighted in blue and green, respectively (ims, intermembrane space). tyr , which is phosphorylated in a tnfα-dependent manner, is highlighted in red. right, higher magnification of the catalytic center in subunit i showing the close proximity of tyr with the binuclear cub-heme a oxygen binding site. histidines , , and , which bind cub and tyr , which is involved in the catalytic cycle of the enzyme, are shown in sticks. i. lee, m. hüttemann / biochimica et biophysica acta ( ) – inner mitochondrial compartments including the intermembrane space and the matrix as predicted by the localization prediction tool psort ii [ ]. if so, due to its broad specificity, it could also act on oxphos. taken together there is clear evidence that oxphos is targeted by cell signaling pathways. however, depending on the animal model and ex- perimental procedures utilized there are some conflicting data regarding oxphos activity and enzyme levels. both enzyme activities of individual complexes and reported protein levels may be affected by phosphoryla- tions. for example, in the latter case it is possible that the epitope(s) rec- ognized by antibodies are masked by phosphorylation, preventing antibody binding and thus erroneously suggesting changes in protein amount. although it is possible that protein degradation is increased during sepsis, in general, under normal conditions mitochondrial protein turnover is slow, with a half life of about and days averaged across several cox subunits in mouse heart and liver, respectively (calculated from [ ]). in patients with sepsis where the condition develops over longer periods of time mitochondrial protein degradation may be a more important contributing factor to mitochondrial dysfunction com- pared to animal studies in which protein levels are analyzed after a few hours. in any case, it might be worth revisiting protein levels in the vari- ous models by comparing results using mitochondrial isolation buffers which lack and contain phosphatase inhibitors, respectively. . reactive oxygen species increased levels of reactive oxygen species and (ros) have long been implicated in sepsis [ , , ]. ros cause tissue damage and they can also trigger apoptosis. therefore, antioxidants and radical scavengers have been proposed as a possible therapy and have shown some efficacy in sepsis models [ , – ]. more recently, ros scaven- gers especially targeted to the mitochondria, such as mitoq, skq , mitoe, and tempol conjugates, which accumulate in the mitochondria manifold raising their effective concentration at the sub-cellular sites needed, were proposed as a novel strategy (reviewed in [ ]). in addi- tion to a direct protective effect by detoxifying ros, scavengers may also affect the communication between immune cells. for example, skq , a mitochondria targeted plastoquinone derivative developed by the skulachev lab [ ], affects levels of certain immune cells, including cd (+) t cells, naïve t cells, and memory t cells [ ]. however, the compound still has to be tested in a sepsis animal model. mitochondria-generated ros may serve as signaling molecules to communicate with the other cellular compartments. complex iii may play a key role in this communication process because it generates ros, which are released into the mitochondrial intermembrane space and thus the cytosol, usually at high mitochondrial membrane poten- tials or in the presence of complex iii inhibitors [ ]. it is possible, how- ever, that different types of immune cells respond differently to ros. for example, it was recently shown that complex iii-generated ros are re- quired for t cell activation [ ]. in contrast, a study using in vitro cul- ture of neutrophils in the presence of lps and inhibitors of complex iii concluded that increased ros levels inhibit inflammatory responses re- quired for the production of cytokines such as tnfα and macrophage inflammatory protein (mip- ) [ ]. another important source of mitochondrial ros is via the p shc pathway [ ]. p shc is intimately linked to oxphos because it accepts electrons from cytc and transfers them to oxygen, generating superoxide. it is activated by phosphoryla- tion and was strongly induced in rodent models of burn trauma and sepsis [ ]. since cytc is also targeted and regulated by phosphoryla- tion [ , , , , ] it is possible that changes in the phosphoryla- tion state of cytc during sepsis may affect its interaction with p shc. finally, in addition to mitochondrial ros production, nadph oxidase- dependent ros generation may significantly contribute to the total ros load during sepsis and could be therapeutically targeted [ ]. although ros are clearly part of the septic sequence their specific role and importance relative to the energy crisis component has to be fur- ther examined. . conclusion our proposed model emphasizes the energetic aspect during acute inflammation. we propose that inflammatory signaling leads to the phosphorylation of cox and other mitochondrial targets followed by the suppression of mitochondrial function, reduced mitochondrial membrane potentials, and energy failure (fig. ). the inhibition of mito- chondrial energy metabolism during sepsis and its life-threatening consequences may, at first sight, not seem reasonable. however, such a systemic condition is very rare in comparison to daily events that gen- erate small wounds and areas of inflammation locally. here, containing the affected area by locally inhibiting mitochondrial function makes sense because some pathogens seize the host energetic infrastructure and energy production system. for example, chlamydiae express a number of nucleotide transporters facilitating the acquisition of mole- cules such as atp [ ]. as a result, inhibiting mitochondria locally at the site of infection might counteract pathogenic growth because im- portant metabolites are no longer generated by the host. however, in the rare condition of a systemic inflammatory response, this response, i.e., the inhibition of mitochondria, might lead to energy depletion, mods, and death. i. lee, m. hüttemann / biochimica et biophysica acta ( ) – future therapeutic approaches should target oxphos and could be combined with strategies already in place that show some effica- cy. several mitochondria-targeted therapies have been tested in- cluding treatment with mitochondrial substrates (e.g., carnitine, succinate, and mgcl –atp), cofactors (e.g., coenzyme q and α-lipoic acid), antioxidants and ros scavengers (e.g., mitoq, skq, phenyl-tert- butylnitrone, n-acetylcysteine, and tempol), and membrane stabilizers (e.g., cyclosporine a and melatonin), which restore mitochondrial func- tion to some extent (reviewed in [ ]). however, interfering with inflammatory signaling at the level of the mitochondria might result in better outcomes. for example, the synthetic cortisol homologue dexamethasone, which affects several signaling pathways including wnt/β-cateninin, nfκb, mapk/erk, and pi k signaling, was shown to partially rescue cox function h after cecal ligation and puncture in the cortex and outer stripe of the outer medulla of mouse kidneys [ ]. additional signaling pathways have been shown to target cox (reviewed in [ ]), which might be explored to boost aerobic activity. among those, non-receptor tyrosine kinase src and protein kinase cε (pkcε) have been identified as positive regulators of cox. in addition to its primary localization in the cytosol src was found in the mito- chondrial intermembrane space [ ]. here it was shown to phos- phorylate cox catalytic subunit ii in osteoblasts on a yet-to-be identified residue leading to enzyme activation [ ]. treatment of rat neonatal cardiac myocytes with pkc activators diacylglycerol or β-phorbol -myristate -acetate ( β-pma) resulted in the phosphor- ylation of an kda protein and a two- to fourfold increase in cox activ- ity [ , ]. it was further shown that pkcε co-immunoprecipitated with cox and that the kda band contained cox subunit iv as identi- fied by mass spectrometry although the precise phosphorylation site still has to be identified. a third kinase that leads to cox activation is matrix-localized carbon dioxide/bicarbonate-regulated adenylyl cyclase which phosphorylates cox subunits i and iv [ ]. there is also evidence that protein tyrosine phosphatase shp , which is part of the ras path- way, directly or indirectly activates cox. similarly to src, shp also local- izes to the mitochondrial intermembrane space [ ]. in mouse cell lines with mutations in the shp- encoding gene ptpn leading to constitu- tively active shp [ ] and in human lymphoblasts with activating mutations we found about % and % increased cox activities, respec- tively [ ]. in conclusion, a better understanding of the multifaceted regulation of oxphos might provide strategies in the future to activate aerobic en- ergy metabolism during acute inflammation by selectively targeting downstream kinases and phosphatases that regulate the activity of the oxphos complexes including the examples discussed above for cox. an important goal should be the identification of kinases and phospha- tases that directly act on oxphos during acute inflammation, which might allow direct control of oxphos activity and restoration of its func- tionality to levels allowing cell survival and maintenance of cellular functions during sepsis in order to decrease mortality. acknowledgements we thank dr. jeffrey doan for comments on the manuscript. this work was supported by a grant from the national institutes of health (gm ), the center for molecular medicine and genetics, and the cardiovascular research institute, wayne state university school of medicine, detroit. references [ ] a.j. ruggieri, r.j. levy, c.s. deutschman, mitochondrial dysfunction and resuscita- tion in sepsis, crit. care clin. 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metabolic switch to strongly inhibit oxphos in acute inflammation
 	 . reactive oxygen species 	 . conclusion 	acknowledgements 	references doi: . /j.tej. . . michael gergen, a partner in latham & watkins’ washington, dc office, is a member of the energy regulatory and markets group and the project development and finance group. mr. gergen has extensive experience developing practical applications of economic theory, corporate finance and regulatory law to assist energy industry clients and other network industry companies to compete successfully in an environment of market-based, open- access competition. mr. gergen represents entities involved in electric generation and transmission, electric and gas marketing and trading, and investment and commercial banking, as well as international governments and financial institutions on a variety of energy-related matters. claudia o’brien is a partner in the washington, dc office of latham & watkins and chair of the firm’s air quality and climate change practice group. her practice is focused on environmental health and safety issues, with an emphasis on emerging trends in air quality control, risk policy, and pesticide and toxic substances regulation. ms. o’brien represents companies and industry groups in petitions, agency rulemaking proceedings, and litigation under a variety of federal environmental statutes, including the clean air act, fifra, the clean water act, epcra, tsca, rcra, and the esa, as well as a number of state environmental laws. eli w.l. hopson is an associate in the washington, dc office of latham & watkins. his practice focuses on energy and environmental regulation, litigation, and transactions, and includes both state and federal regulatory work. david e. pettit is an associate in the washington, dc office of latham & watkins. his practice focuses on energy regulations and markets. - /$ – see front matter # else walking the line between the clean air act and the federal power act: balancing emission reductions and bulk power reliability a power plant can find itself subject to potential liability under the clean air act if it does not cease or greatly reduce operations and at the same time be compelled by the department of energy and/or the federal energy regulatory commission acting under the federal power act to keep operating to ensure reliability. there needs to be cooperation among the federal agencies to create a stable and predictable regulatory environment at a minimum and, more preferably, a comprehensive solution to prevent this conflict from occurring in the first place. michael gergen, claudia o’brien, eli w.l. hopson and david e. pettit r ecent rounds of regulationsby the environmental protection agency (epa) have renewed a critical unresolved legal question for operators of power plants, one that impacts the reliability of the nation’s bulk vier inc. all rights reserved., doi:/ . /j. power grid: what happens when a plant is subject to potential liability under the clean air act (caa) if it does not cease or greatly reduce operations, and at the same time is compelled by the department of energy (doe) and/or the federal tej. . . the electricity journal http://dx.doi.org/ . /j.tej. . . conflict between the caa and fpa is more likely to arise for plants seeking to retire rather than install control systems for which reliability solutions such as new generation or transmission upgrades are not practical. ja energy regulatory commission (ferc) acting under the federal power act (fpa) to keep operating to ensure reliability? although this scenario may arise for plants installing emission control systems to obtain compliance with the caa, conflict between the caa and the fpa is more likely to arise for plants seeking to retire rather than install control systems for which reliability solutions such as new generation or transmission upgrades are not practical under the time constraints imposed by the caa. in this article we summarize the statutory background for such potential conflicts between the caa and the fpa, explore previous instances where these laws were in conflict, and discuss the recent regulations and how conflicts arising under them might be addressed by epa, doe, and ferc. i. bulk power reliability and the federal power act both doe and ferc have ways to address bulk power reliability concerns pursuant to various provisions of the fpa. doe has invoked its authority several times since , while ferc has only invoked its authority once and in a manner complementary to authority already exercised by doe. a. doe’s authority under the fpa section (c) of the fpa empowers the secretary of energy n./feb. , vol. , issue - /$–s to order power plants to operate for reliability reasons during emergency situations. the statute specifically provides that ‘‘whenever the commission determines that an emergency exists . . . the commission shall have authority . . . to require by order such temporary connections of facilities and such generation, delivery, interchange, or transmission of electric energy as in its judgment will best meet the emergency and serve the public interest.’’ e ven though the language inthe fpa refers to ‘‘the commission,’’ the authority to require power plants to operate in fact lies with the secretary of energy and doe. the department of energy organization act transferred the powers previously vested with the federal power commission to doe unless the authority is expressly reserved to ferc. while doe has vested certain powers with ferc, such as those provided in sections (a) and (b) of the fpa, doe has retained its authority under section (c). ee front matter # elsevier inc. all rights r not only has doe retained this authority, it has interpreted its potential application broadly. doe has defined an ‘‘emergency’’ to include, among other things, ‘‘an unexpected inadequate supply of electric energy.’’ perhaps presciently, doe also included ‘‘regulatory action which prohibits the use of certain electric power supply facilities’’ in its definition of ‘‘emergency.’’ h owever, section (c)does not require doe to take action; instead, it simply provides doe with the authority to take action if it so chooses. as discussed in more detail below, doe has invoked this authority in several instances since . b. ferc’s authority under the fpa section (c) is not the only provision of the fpa that appears to provide a federal agency with the authority to ensure the reliability and adequacy of electric service. section of the fpa states that upon a complaint by a state commission, ‘‘[w]henever the commission . . . shall find that any interstate service of any public utility is inadequate or insufficient, the commission shall determine the proper, adequate or sufficient service to be furnished, and shall fix the same by its order, rule or regulation . . . .’’ while this authority lies with ferc, it has only been invoked on one occasion—and in that instance, doe had already ordered a plant to generate eserved., doi:/ . /j.tej. . . http://dx.doi.org/ . /j.tej. . . section arguably allows ferc to consider reliability concerns in determining whether a utility is providing adequate or sufficient service. electricity pursuant to section (c). specifically, in , ferc used its authority under section to require pjm interconnection, llc, (pjm) and the potomac electric power company (‘‘pepco’’) to ‘‘file a long-term plan to maintain adequate reliability in the washington, dc, area and surrounding region, and a plan to provide adequate reliability pending implementation of this long-term plan.’’ aside from this instance, ferc has refrained from using this authority. h owever, section arguably allows ferc to consider reliability concerns in determining whether a utility is providing adequate or sufficient service. while ferc’s authority is contingent upon a complaint by a state commission, section mandates that ferc take action to remedy the problem upon a finding of inadequate service. in contrast, section (c) simply provides doe with the discretion to take action, though doe can do so on its own accord. section of the fpa augments ferc’s authority by permitting it ‘‘to perform any and all acts, and to prescribe, issue, make, amend, and rescind such order, rules, and regulations as it may find necessary or appropriate to carry out the provisions of [the fpa].’’ courts, however, have narrowly construed section , stating that it ‘‘merely augment[s] existing powers’’ and allows ferc to ‘‘use means of regulation not spelled out in detail.’’ as such, ferc would most likely need to - /$ – see front matter # else rely on another provision, perhaps in conjunction with section , to address reliability concerns. ii. epa’s authority under the clean air act to regulate power plants epa has broad authority to regulate power plant operation. for coal fired-power plants, epa has recently proposed and in some cases finalized new regulations that would affect emissions of pollutants, handling of the byproducts of coal combustion, and cooling-water intake structures. these regulations are promulgated under the caa, the resource recovery and conservation act (rcra), and the clean water act (cwa), respectively. although all of the rules published by epa have the potential to impact reliability, epa’s recently finalized emissions limits for hazardous air pollutants and for pollutants that cross state lines for utility-scale energy generating units will be the first to impact vier inc. all rights reserved., doi:/ . /j. operating power plants. as the rcra rules relating to coal combustion byproducts and the cwa rules on cooling water intakes are still in the draft stage, with no clear statutory deadline for implementation, we focus our discussion on the potential conflict between the caa rules and ferc and doe’s responsibilities under the fpa. a. epa’s authority under the caa . national ambient air quality standards epa is directed under section (b)( ) of the caa to create national standards, the national ambient air quality standards (naaqs), to limit levels of pollutants that are harmful to public health and welfare. the caa is a partnership of federal and state regulation, with section directing each state to adopt a state implementation plan (sip), which epa must then approve. once approved, the sip is effectively a federal law, and enforceable as such. the caa further provides that once approved, no federal entity ‘‘shall engage in, support in any way, or provide financial assistance for, license or permit, or approve, any activity which does not conform to an implementation plan after it has been approved . . ..’’ the statute defines conformity as: ‘‘(a) conformity to an imple- mentation plan’s purpose of eliminating or reducing the severity and number of violations tej. . . the electricity journal http://dx.doi.org/ . /j.tej. . . ja of the [naaqs] and achieving expeditious attainment of such standings; and (b) that such activities will not - (i) cause or contribute to any new violation of any standard in any area; (ii) increase the severity of any existing violation of any standard in any way; or (iii) delay timely attainment of any standard or any required interim emission reductions or other milestones in any area.’’ although broadly drafted, there are limitations on the scope of the conformity requirement. a lthough broadly drafted,there are limitations on the scope of the conformity requirement. initially, the conformity analysis only covers ‘‘major’’ federal actions; for actions emitting less than the threshold, conformity is presumed. de minimis actions are also explicitly excluded by regulation. epa’s regulations also specifically exclude ‘‘actions in response to emergencies or natural disasters such as hurricanes, earthquakes, etc., which are commenced on the order of hours or days after the emergency or disaster’’ or ‘‘actions which are a part of a continuing response’’ to said emergency or disaster, although the federal agency taking the action must make a written determination that the conformity analysis is impractical for a period of up to six months ‘‘due to overriding concerns for public health and welfare, national security interests and foreign policy commitments.’’ caa section (f) also contains a non- delegable presidential temporary n./feb. , vol. , issue - /$–s waiver for energy emergencies, which is limited to a period of four months. some courts have interpreted epa’s authority to act pursuant to the caa as discretionary, with the court in seabrook v. costle noting that no section of the caa ‘‘imposes a mandatory duty on the administrator to make a finding every time some information concerning a possible violation of a sip is brought to [her] attention.’’ the naaqs provisions of the caa do not directly address conflicts with other laws. . mercury and air toxics standards epa is directed under section to regulate power plant emissions of hazardous pollutants. congress required epa to study power plant emissions of hazardous air pollutants under section (n)( ). following presentation of that study to congress, the statute required epa to regulate power plants ‘‘if the administrator finds such regulation is appropriate and ee front matter # elsevier inc. all rights r necessary.’’ epa issued a determination that regulating the emissions of hazardous air pollutants from power plants was ‘‘appropriate and necessary’’ in , and promulgated regulations that have since been vacated by the d.c. circuit. subsequently several environmental and public health organizations filed a complaint alleging that epa had not performed a mandatory duty under the caa to regulate hazardous air pollutants from coal and oil-fired electrical generating units (egus). epa settled the case, and under the consent decree was required to issue a notice of final rulemaking by dec. , . t he mercury and air toxicsstandards (mats) standards for existing power plants are technology-based emissions limits, with the administrator required to set levels equivalent to the average emissions of the best-performing percent of plants. epa must set the effective date no later than three years after the rule is published. under the caa, either the administrator or a delegated state may issue an extension of up to one year ‘‘if such additional period is necessary for the installation of controls.’’ the president may also grant an exemption for up to two years if ‘‘the president determines that the technology to implement such standard is not available and that it is in the national security interests of the united states to do so.’’ eserved., doi:/ . /j.tej. . . http://dx.doi.org/ . /j.tej. . . a s with the naaqs, there isno language under the mats that clarifies how to resolve conflicts with other laws. similarly, there is no language in the other sections of the caa. the caa does generally provide authority for citizen suits against any person, including the administrator, for violations of the act or failure of the administrator to perform a required duty. bulk power reliability concerns have iii. past conflicts between the caa and the fpa led doe to exercise its authority under section (c) of the fpa on several occasions since . bulk power reliability concerns have led doe to exercise its authority under section (c) of the fpa on several occasions since . for example, doe ordered the cross-sound cable, an underwater transmission line running between connecticut and long island, to operate during back-to-back summers due to a summer heat wave in and the northeast blackout in . however, there have been two instances in recent years where some electric power generators have faced a dilemma between complying with the caa and following an order under the fpa to generate electricity. a. the potomac river generating station the potomac river generating station is a mw coal-fired power plant in alexandria, va., that provides electricity for - /$ – see front matter # else portions of the district of columbia, including the blue plains advanced water treatment plant—one of the largest wastewater treatment plants in the world. on aug. , , mirant corporation, the owner of the station, submitted a computerized emissions model to the virginia department of environmental quality (vdeq) indicating that emissions from the station either caused or contributed to localized exceedances of the naaqs. in response to a subsequent letter from vdeq, mirant shut down all five of the station’s generating units on aug. , . that same day, the district of columbia public service commission (dcpsc) filed a petition with both doe and ferc requesting that mirant be compelled to operate the station to maintain reliability in the district of columbia. based on the ‘‘reasonable possibility an outage will occur that would cause a blackout,’’ doe responded to the dcpsc’s petition by ordering mirant to vier inc. all rights reserved., doi:/ . /j. resume operations pursuant to section (c) of the fpa. ferc also responded by requiring long- term reliability plans from pjm and pepco pursuant to section of the fpa. doe’s order to resume operation did not, however, expressly alleviate mirant from possible penalties for exceeding the naaqs. in its order, doe sought to walk the line between reliability and potentially adverse environmental impacts by specifying the manner in which mirant was to operate the station. doe also stated that if epa issued a compliance order, then doe would consider whether and how to conform its order accordingly. sure enough, six months later, epa issued a compliance order instructing mirant to use so emission controls and to operate only when daily modeling indicated that it would comply with the naaqs. however, the compliance order also required mirant to operate the station ‘‘as specified by pjm and in accordance with the [ ] doe order.’’ m irant successfullyoperated the station pursuant to the orders by doe and epa for over a year. on feb. , , however, mirant’s luck ran out. by operating in accordance with doe’s order to run for reliability purposes, the station exceeded its three-hour naaqs limit and the vdeq consequently fined mirant for naaqs exceedances. this situation was unfortunately not the first time a tej. . . the electricity journal http://dx.doi.org/ . /j.tej. . . ja generator faced a dilemma involving the caa and the fpa. b. the california energy crisis near the end of and into , the state of california experienced an unexpected electricity shortage. doe responded by ordering certain generation facilities to make energy available to the california independent system operator (caiso) for a period of approximately two months. i n addition to the action takenby doe, ferc also instituted a ‘‘must-offer obligation’’ mandating that all non- hydroelectric generators offer all of their available capacity into the spot market during all hours. in light of comments filed by generators, ferc recognized that the must-offer obligation could result in generators operating in violation of their certificates or applicable law. to mitigate this situation, the must-offer requirement did not require generators to run if doing so would otherwise break the law. in a subsequent order, ferc clarified that a generator could go so far as to seek a declaratory order from the courts finding that compliance with the must-offer obligation would result in permit violations if it wanted to prevent citizen suits alleging violations of environmental regulations. this clarification came about in response to a citizen suit against a generator, which the generator settled at a significant cost. n./feb. , vol. , issue - /$–s iv. potentially potent rulemakings a. epa’s finalized regulations . cross-state air pollution rule on july , , epa finalized regulations requiring significant reductions in so and nox emissions. epa issued the regulations in response to the d.c. circuit’s remand of a prior version of the rule, the clean air interstate rule (cair). epa proposed technical adjustments on oct. , , and finalized a supplemental rule including additional states on dec. , . epa estimates that costs associated with csapr are $ million annually in , on top of $ . billion per year in capital investments that were being made in response to the previous rulemaking. epa expects facilities to use dry and wet flue-gas desulfurization (fgd), dry sorbent injection, selective catalytic reduction (scr), and some fuel switching and process optimization. the initial compliance phase was to begin on ee front matter # elsevier inc. all rights r jan. , ; however, the d.c. circuit stayed csapr on december , in eme homer city generation, l.p. v. epa and ordered the parties to propose briefing schedules so that the case could be heard by april . as the rule stands now, the second, more stringent compliance phase begins on jan. , . . mats for utility generators on dec. , , epa finalized regulations limiting the emissions of mercury and other hazardous pollutants from egus. epa estimates that the total cost of the rule will be $ . billion annually in . some industry estimates are significantly higher. epa expects plants that are installing controls to use a mixture of available technologies, including scr with fgd, activated carbon injection (aci), aci with a fabric filter, dry sorbent injection, and electrostatic precipitators. costs for individual plants will vary, but for facilities with no pollution controls, compliance costs are expected to run into the hundreds of millions of dollars per plant. epa made small revisions to the proposal as a result of comments received, which according to epa’s estimates reduced the costs of compliance by about $ billion. epa grants the statutory maximum of three years and days from the published date for compliance with the mats rule, meaning the earliest compliance date would be march . as discussed above, generators that are installing controls may be eserved., doi:/ . /j.tej. . . http://dx.doi.org/ . /j.tej. . . eligible for an additional one-year extension from either the state managing the program or the administrator. in two memoranda released with the final rule, one from epa and one from the president, the administration states that although unlikely to be required, epa can issue administrative orders that would absolve violators who were operating subject to critical reliability concerns of complying with the caa for one year under section (a) (governing enforcement of violations). however, as discussed above, prior experiences indicate that the administrative order process may not protect against all risks to companies required to operate for reliability reasons, as citizen suits may be filed by individuals or organizations other than epa. the memoranda also make clear that the administration intends to make the standard one-year extension for installation of controls under section (i)( )(b) ‘‘broadly available’’; however, the applicability of that extension to facilities that plan on retiring is uncertain. neither memorandum mentions the president’s authority under section (i)( ), so the breadth of that additional exemption, and the administration’s willingness to invoke it, are unclear. b. epa’s proposed regulations epa has also proposed two other rules that are likely to have a significant cost impact on certain - /$ – see front matter # else coal-fired electrical generating units, potentially including some that are critical to reliability. the first rule, proposed on june , , with a subsequent notice of data availability issued on oct. , , deals with the treatment of coal combustion byproducts. two regulatory schemes were proposed by epa under rcra, with the first being to regulate coal combustion residuals under subtitle c of rcra, which covers the cradle-to-grave treatment of hazardous waste. epa’s second proposal would regulate the coal byproducts under subtitle d of rcra, the section regulating non- hazardous wastes. epa has indicated that a final rule will not be issued until late ; thus the nature of the regulation and the timeline for implementations are unclear. the second proposed regulation is for the intake of cooling water. epa has proposed regulations that would cover the impingement (trapping of fish against the intake screen) and entrainment (fish that are drawn into the power plant and affected vier inc. all rights reserved., doi:/ . /j. by heat or other stress) of fish and other aquatic life. epa has signed a consent decree with the environmental group riverkeeper indicating that it will issue final actions by july , , although the implementation period for existing plants is still unknown. c. anticipated impacts on bulk power reliability at least a dozen studies have attempted to analyze the potential reliability impacts associated with the recent suite of new regulations by epa. however, all of these studies face the same problem— we do not have all of the final rules yet, and companies’ responses to the finalized rules are still being developed. a t ferc’s recent reliabilitytechnical conference, pjm pointed out that there is a chicken-or-the-egg issue with respect to identifying the impacts on reliability that the proposed rules will have before epa issues its final rules. the problem is that reliability impacts cannot be reliably estimated until generators identify which units they will retire. at the same time, generators cannot know which units to retire until they have all of the final rules from epa and have had time to analyze the final regulations. so, in the meantime, the best approach is to attempt to identify all ‘‘at risk’’ generation to understand the possible spectrum of reliability impacts. as a result, there is a variety of studies that make varying assumptions and come to sometimes tej. . . the electricity journal http://dx.doi.org/ . /j.tej. . . ja dramatically different conclusions. r egardless of the extent ofretirements anticipated across the country, the situation with the potomac river generating station indicates that the early retirement of even a single plant can lead to a localized reliability issue. accordingly, doe, ferc, and epa should take steps to coordinate the implementation of these rules in a predictable manner that does not place generators in the position faced by the potomac river generating station. v. potential outcomes for resolving reliability conflicts epa, ferc, utilities, and regulators have all proposed a number of different solutions for resolving any potential conflict. we discuss below a number of the solutions that have been proposed or that are present in the underlying statutes. these solutions can generally be grouped into three categories: actions by epa or the states to waive environmental laws, presidential extensions, or actions by doe or ferc to force regulated entities to violate environmental laws, while potentially protecting those entities. a. reliability safety valve although this phrase has been incorporated into a number of n./feb. , vol. , issue - /$–s different proposals describing different mechanisms, most commonly the ‘‘reliability safety valve’’ refers to a proposal put forward in joint comments on the mats proposed rule from several independent system operators (isos) and regional transmission organizations (rtos). the joint rto commentors proposed that a retiring generator that is determined to be critical for system reliability be allowed to operate for an additional fourth year, or longer if more time is required to address the reliability issue. the rto comments propose limiting the extension to situations where the generator provides an early notice of impending retirement, the iso/ rto identifies the unit as critical to reliability, and the upgrades or replacements necessary to address the reliability problem are expected to take more than three years. epa has adopted some aspects of this proposal into its enforcement memorandum issued with the final mats rule, although the additional extension ee front matter # elsevier inc. all rights r for units critical to reliability would operate via administrative order under section (a), and would be limited to a period of one year. on the other hand, neither the presidential memo nor epa enforcement memorandum clarify whether the separate ‘‘broadly available’’ one-year extension under section (i)( )(b) would be available to facilities that are shutting down. notably epa indicates that the administrative orders under section (a) would be granted to facilities that are moving into retirement, not just for facilities installing controls, or being replaced with new generation onsite. potentially more problematic is epa’s statement that the orders would not be issued before the compliance date, creating the potential for a conflict until the order is posted. in addition, the administrative orders may not remove risks from citizen suits, as previously discussed in the context of the california energy crisis. a longer-term solution couldbe to amend the fpa to make clear that those operating under an emergency order issued by doe pursuant to its authority under section (c) of the fpa are not subject to civil or criminal liability for violating environmental laws or regulations. this has the advantage of addressing any future concerns under other environmental statutes, but may be challenging to pass in a tough legislative environment. eserved., doi:/ . /j.tej. . . http://dx.doi.org/ . /j.tej. . . b. presidential extensions under both csapr and mats, the caa includes a presidential waiver that could be used to temporarily extend compliance deadlines for individual facilities. while the administration has not expressed a view as to the potential for use of these statutory exemptions, they remain possible uses for particular situations. although the csapr exemption is limited to only four months by the statute, the presidential exemption under section could theoretically be reissued indefinitely for two-year terms if required. given the potential for long timelines for siting new power plants and transmission lines, this backstop authority may become useful if the other extensions epa has proposed are exhausted. c. compelled operation to protect bulk power reliability if an extension, consent decree, or similar waiver cannot be obtained for a unit that is critical to reliability, doe might choose, as it has previously, to apply its authority under fpa section (c) to require a facility to run. yet none of the issues raised by the potomac river and california energy crisis situations discussed above have been resolved, leading to significant uncertainty for plant operators. under ferc’s supervision, units that are critical to reliability and planning to retire may be able to negotiate distributed financial burdens for - /$ – see front matter # else installing controls, or indemnity against any future costs. alternatively, similar to the ferc’s approach during the california energy crisis, any orders that require a generating facility to operate could be limited so as to make clear that the order would not apply if compliance would result in a violation of the facility’s certificate or applicable law. vi. which statute controls if another conflict arises? despite the numerous proposals and possible coordination among federal agencies, it is plausible that another conflict will occur between the caa and the fpa, just as it did with respect to the potomac river generating station. if another conflict occurs, the question of which statute controls may very well come before the courts. a court will first look to the statutes to see if either specifically addresses conflicts of law. in this case, neither the caa nor the vier inc. all rights reserved., doi:/ . /j. fpa expressly or impliedly trump one another. in the absence of a conflicts-of-law provision, a court will then attempt to harmonize the provision so as to avoid the conflict. as discussed above, there is a potentially critical difference between sections (c) and of the fpa in that doe’s authority under section (c) is discretionary, while section mandates ferc to ‘‘fix’’ inadequate service. courts have held that certain environmental statutes must yield if their application prevents a federal agency from fulfilling a nondiscretionary legislative mandate. because of the nondiscretionary mandate of section , a court could find that ferc’s action pursuant to section cannot be waived or limited by conflicting caa provisions. h owever, a court may not beable to harmonize section (c) of the fpa and the caa amendments in the more likely event that doe orders a generating facility to operate such that it violates the naaqs. in such a scenario, courts will apply two basic principles of statutory interpretation: ( ) the more recent statute controls, and ( ) the more specific statute controls. congress amended the caa in to implement the naaqs. in , congress enacted sections , , and of the fpa. based on these facts, a court could determine that the caa amendments repealed by implication the conflicting tej. . . the electricity journal http://dx.doi.org/ . /j.tej. . . there needs to be cooperation among the federal agencies to create a stable and predictable regulatory environment. ja provisions of the fpa. however, courts disfavor a finding that a statute was repealed by implication and will look to determine whether the legislative intent to repeal was clear and manifest. here, such a determination would be unlikely because there is no evidence that congress intended the caa amendments to repeal any conflicting provision of the fpa. m oreover, a more specificstatute will control over a more general one. the more specific statute may even take priority over another statute enacted by congress more recently. here, both statutes require specific directives to be applied to individual generating n./feb. , vol. , issue - /$–s facilities. the caa calls for epa to regulate generating facilities and mandate compliance with the naaqs. the fpa, on the other hand, provides the authority to require certain plants to operate for reliability purposes as directed by doe. thus, while both statutes provide specific directives, it is not unlikely that a court could find that section (c) of the fpa supersedes the caa. r egardless of whether thecaa or the fpa (section (c) and/or section ) controls, there needs to be cooperation among the federal agencies to create a stable and predictable regulatory environment at a minimum and more preferably, a comprehensive solution to prevent this conflict ee front matter # elsevier inc. all rights r from occurring in the first place.& endnotes: . u.s.c. § a(c). . see u.s.c. § (b). . c.f.r. § . . . id. . u.s.c. § f. . district of columbia public service commission, ferc � , at p ( ). . see, e.g., arkansas public service commission v. entergy service, inc. et al., ferc � , ( ). . william l. massey, robert s. fleishman and mary j. doyle, reliability-based competition in wholesale electricity: legal and policy perspective, energy l.j. , ( ). eserved., doi:/ . /j.tej. . . http://dx.doi.org/ . /j.tej. . . . u.s.c. § f. . u.s.c. § a(c). . u.s.c. § h. . new england power co. v. fed. power comm., f. d , (d.c. cir. ). . niagara mohawk power corp. v. fed. reg. energy comm., f. d , (d.c. cir. ). . u.s.c. § . . u.s.c. § . . see, e.g., her majesty the queen v. city of detroit, f. d ( th cir. ) (holding that once a sip is approved by the epa, its requirements become federal law and are fully enforceable in federal court). . u.s.c. § (c)( ). . id. . see c.f.r. § . (b) – (c). . c.f.r. § . (c). . id. §§ . (d)( ), (e). . u.s.c. § (f). . city of seabrook v. costle, f. d ( th cir. ) (‘‘seabrook’’); see also yakima v. surface transp. bd., f.supp. d (e.d. wa. ). . u.s.c. § (n)( ). . fed. reg. - (dec. , ). . new jersey v. epa, f. d , (d.c. cir. ). . american nurses association, chesapeake bay foundation, inc., conservation law foundation, environment america, environmental defense fund, izaak walton league of america, natural resources council of maine, natural resources defense council, physicians for social responsibility, sierra club, the ohio environmental council, and waterkeeper alliance, inc. (civ. no. : -cv- (rmc)), at: http:// www.epa.gov/ttn/atw/utility/ consentfnl.pdf. . note that the original date of nov. , , was modified by consent of - /$ – see front matter # else the parties, as described in paragraph (b). id. . u.s.c. § (d)( ). . u.s.c. § (i)( ). . id. . u.s.c. § (i)( ). . . u.s.c. § (a). . doe order - - , order pursuant to section (c) of the federal power act (aug. , ). . doe order - - , order pursuant to section (c) of the federal power act (aug. , ); doe order - - , order pursuant to section (c) of the federal power act (aug. , ). . district of columbia public service commission, doe order - - at – (dec. , ), at http:// www.gc.doe.gov/sites/prod/files/ oeprod/documentsandmedia/ mirant_ _ .pdf (hereinafter ‘‘ doe order’’). . id. at . . id. mirant subsequently resumed operating one unit for hours of each -hour period prior to doe’s order that it released on dec. , . both epa and vdeq acknowledged that this minimal operation of the station did not result in naaqs exceedances. id. at . . emergency petition and complaint of the district of columbia public service commission, docket vier inc. all rights reserved., doi:/ . /j. nos. eo- - (doe), el - - (ferc) (filed aug. , ). . doe order at . as an example of the potential ramifications of a blackout, pepco stated that ‘‘within hours of the loss of electric supply, blue plains will have no option but to release untreated sewage directly into the potomac river.’’ id. at . . district of columbia public service commission, ferc � , ( ). . doe order at , – . . reliability technical conference, docket no. ad - - , et al., speaker materials of debra raggio, genon energy (filed nov. , ), attachment d, mirant potomac river llc, docket no. caa- - - da, administrative compliance order by consent (june , ); epa, press release, epa issues administrative order to mirant potomac river—order sets schedule for mirant to comply with clean air standards (june , ). . reliability technical conference, docket no. ad - - , et al., speaker materials of debra raggio, genon energy (filed nov. , ), attachment d, mirant potomac river llc, docket no. caa- - - da, administrative compliance order by consent at (june , ). . see reliability technical conference, docket no. ad - - , et al., speaker materials of debra raggio, genon energy at – (filed nov. , ), attachments e and f. . see notice of issuance of emergency orders under section (c) of the federal power act, fed. reg. , (dec. , ); see also doe order, order pursuant to section (c) of the federal power act (jan. , ). . san diego gas & elec. co. v. sellers of energy & ancillary servs., ferc � , at , ( ). the must-offer obligation stemmed from an investigation into the reasonableness tej. . . the electricity journal http://www.epa.gov/ttn/atw/utility/consentfnl.pdf http://www.epa.gov/ttn/atw/utility/consentfnl.pdf http://www.epa.gov/ttn/atw/utility/consentfnl.pdf http://www.gc.doe.gov/sites/prod/files/oeprod/documentsandmedia/mirant_ _ .pdf http://www.gc.doe.gov/sites/prod/files/oeprod/documentsandmedia/mirant_ _ .pdf http://www.gc.doe.gov/sites/prod/files/oeprod/documentsandmedia/mirant_ _ .pdf http://www.gc.doe.gov/sites/prod/files/oeprod/documentsandmedia/mirant_ _ .pdf http://dx.doi.org/ . /j.tej. . . ja of rates for the sale of electric energy in the caiso and px spot markets by ferc pursuant to its authority under section of the fpa. . id. . san diego gas & elec. co. v. sellers of energy & ancillary servs., ferc � , at , ( ) (‘‘in sum, in order to be exempted from the must offer requirement, a generator must demonstrate that running its unit violates a permit, would result in a criminal or civil violation or penalties, or would result in qf units violating their contracts or losing their qf status. in lieu of submitting a presentation such as that filed by mirant, a generator may obtain a declaratory order from an appropriate court finding that the generator’s compliance with the must offer requirement will result in a violation of its permit.’’). . see reliability technical conference, docket no. ad - - , et al., speaker materials of debra raggio, genon energy at (filed nov. , ). . fed. reg. (august , ) (hereinafter ‘‘csapr’’). . csapr at , . . revisions to federal implementation plans to reduce interstate transport of fine particulate matter and ozone, fed. reg. , ; federal implementation plans for iowa, michigan, missouri, oklahoma, and wisconsin and determination for kansas regarding interstate transport of ozone, docket id: epa-hq-oar- - (dec. , ) (to be codified at c.f.r. parts and ). . epa, cross-state air pollution rule, reducing air pollution protecting public health, presentation (dec. , ) (at: http:// www.epa.gov/airtransport/pdfs/ csaprpresentation.pdf). . csapr at , . . see eme homer city generation, l.p., et al. v. epa, no. - (d.c. cir. dec. , ) (order granting requested stay). n./feb. , vol. , issue - /$–s . csapr at , . . national emission standards for hazardous air pollutants from coal and oil fired electric utility steam generating units, docket id epa-hq-oar- - , pre- publication version, (to be codified at c.f.r. part ) (hereinafter ‘‘mats’’). . epa fact sheet: mercury and air toxics standards, adjustments from proposal to final, dec. , ; mats at . . comments of the utility air research group on epa’s national emission standards for hazardous air pollutants from coal and oil-fired electricity steam generating units, at , docket epa-hq-oar- - (aug. , ). . study of hazardous air pollutant emissions from electric utility steam generating units – final report to congress, epa, (feb. ), at: http:// www.epa.gov/ttn/atw/combust/ utiltox/eurtc .pdf. . see north american electric reliability corporation, special reliability scenario assessment: resource adequacy of potential u.s. environmental regulations (oct. ), at http://www.nerc.com/files/ epa_scenario_final.pdf (hereinafter ‘‘nerc report’’). . epa fact sheet: mercury and air toxics standards, adjustments from proposal to final, dec. , . ee front matter # elsevier inc. all rights r . mats at . . id. . see memorandum for the administrator of the environmental protection agency, flexible implementation for the mercury and air toxics standards rule, from barack obama (dec. , ) (hereinafter ‘‘presidential memo’’); memorandum, the environmental protection agency’s enforcement response policy for use of clean air act section (a) administrative orders in relation to electric reliability and the mercury and air toxics standard, from cynthia giles (december , ) (‘‘enforcement memo’’). . presidential memo at . . fed. reg. , (june , ). . fed. reg. , (oct. , ). . epa eyes late for coal ash reuse risk analysis ahead of final rule, inside epa (dec. , ) (quoting administrator jackson, ‘‘i think it’s going to be towards the end of the year.’’). . fed. reg , (july , ). . see settlement agreement among the united states environmental protection agency, plaintiffs in cronin, et al. v. reilly, civ. (lts(sdny), and plaintiffs in riverkeeper, et al. v. epa, civ. (pkc)(sdny) (nov. , ) as subsequently amended (available at: http:// water.epa.gov/lawsregs/ lawsguidance/cwa/ b/phase / upload/ bsettlement.pdf). . reliability technical conference, docket no. ad - - , et al., pjm, interconnection, l.l.c. testimony of mike kormos at (filed nov. , ) (hereinafter ‘‘pjm testimony’’). . id. to date, pjm has not identified any ‘‘overarching reliability impacts associated with potentially retiring units that cannot be resolved with transmission upgrades within the four year period allowed by the proposed mats rule.’’ id. at . eserved., doi:/ . /j.tej. . . http://www.epa.gov/airtransport/pdfs/csaprpresentation.pdf http://www.epa.gov/airtransport/pdfs/csaprpresentation.pdf http://www.epa.gov/airtransport/pdfs/csaprpresentation.pdf http://www.epa.gov/ttn/atw/combust/utiltox/eurtc .pdf http://www.epa.gov/ttn/atw/combust/utiltox/eurtc .pdf http://www.epa.gov/ttn/atw/combust/utiltox/eurtc .pdf http://www.nerc.com/files/epa_scenario_final.pdf http://www.nerc.com/files/epa_scenario_final.pdf http://water.epa.gov/lawsregs/lawsguidance/cwa/ b/phase /upload/ bsettlement.pdf http://water.epa.gov/lawsregs/lawsguidance/cwa/ b/phase /upload/ bsettlement.pdf http://water.epa.gov/lawsregs/lawsguidance/cwa/ b/phase /upload/ bsettlement.pdf http://water.epa.gov/lawsregs/lawsguidance/cwa/ b/phase /upload/ bsettlement.pdf http://dx.doi.org/ . /j.tej. . . . see, e.g., nerc report (finding - gw of coal-fired generation to be retired by ); see also edison electric institute, potential impacts of environmental regulation on the u.s. generation fleet (jan. ), at http:// www.pacificorp.com/content/dam/ pacificorp/doc/energy_sources/ integrated_resource_plan/ irp/ eeimodelingreportfinal- january .pdf (finding - gw of unplanned coal-fired generation retirements by ) (hereinafter ‘‘eei report’’); fitch: new epa rule likely to speed plant retirements, wall st. j. (dec. , ) (citing fitch ratings, time to retire? ii the update to coal plant retirements (nov. , )) (indicating up to gw of coal-fired generation may be retired due to various epa rules). . joint comments of the electric reliability council of texas, the midwest independent transmission system operator, the new york independent system operator, pjm interconnection, llc, and the southwest power pool, docket nos. epa-hq-oar- - , et al. (oct. , ), at http://pjm.com/�/ media/documents/other-fed-state/ -epa-hq-oar- - -iso- rto.ashx (‘‘joint rto comments’’). . id. at . . id. at . . see enforcement memo. . see enforcement memo; presidential memo. . enforcement memo at – . . id. at . . see press release, sen. murkowski (r-alaska), reliability concerns warrant careful review of utility mact rule, (dec. , ), at http:// energy.senate.gov/public/index. cfm?fuseaction=pressreleases. detail&pressrelease_id= c -c aa- c - - a a bff & month= &year= &party= . . see for example exelon generation company, llc, order accepting and suspending tariff filing at para. – , ferc � , (sep. , ). - /$ – see front matter # else . see, e.g., blue chip stamps. v. manor drug stores, u.s. at ( ) (‘‘the starting point in every case involving construction of a statute is the language itself’’). . see, e.g., watt v. alaska, u.s. , ( ) (courts will read conflicting statutes ‘‘to give effect to each if [courts] can do so while preserving their sense and purpose’’); morton v. mancari, u.s. at – ( ) (‘‘the courts are not at liberty to pick and choose among congressional enactments, and when two statutes are capable of co- existence, it is the duty of the courts, absent a clearly expressed congressional intention to the contrary, to regard each as effective’’). . see, e.g., nat’l ass’n of home builders v. defenders of wildlife, u.s. , – ( ) (holding that the endangered species act’s ‘‘no- jeopardy duty only applies to discretionary agency actions and does not attach to actions . . . that an agency is required by statute to undertake once certain specified triggering events have occurred’’); flint ridge dev. co. v. scenic rivers ass’n, u.s. at ( ) (where a clear and unavoidable conflict in statutory authority exists, ‘‘nepa must give way’’); see also operation of the mo. river syst. litigation, f. d , ( th cir. ) (stating that environmental statutes ‘‘do not apply where they would render an agency unable to fulfill a non-discretionary statutory purpose. . .’’). vier inc. all rights reserved., doi:/ . /j. . see nat’l wildlife federation v. us army corps of engineers, f. d , ( th cir. ) (holding that the construction and operation of dams in accordance with congressional mandates did not violate clean water act provisions despite causing exceedances); platte river whooping crane critical habitat maintenance trust v. ferc, f. d (d.c. cir. ) (holding that the endangered species act does not alter the scope of ferc’s authority under the fpa). . with respect to the potomac river generating station, the vdeq argued that the caa and the fpa did not conflict because both doe and ferc must consider and, if necessary, mitigate proposed actions under the national environmental policy act (nepa). motion to intervene and protest of virginia department of environmental quality director robert g. burnley, docket no. el - - (filed aug. , ). however, this argument failed to take into account the fact that doe orders issued in response to emergency situations are exempt from nepa. see c.f.r. . . because doe can only order a generating facility to operate in an emergency situation, nepa will not apply. . see watt, u.s. at - (citing a c. sands, sutherland on statutes and statutory construction section . ( th ed. )). . posadas v. national city bank, u.s. , ( ) (‘‘the cardinal rule is that repeals by implication are not favored’’). . see bulova watch co. v. united states, u.s. , (‘‘it is familiar law that a specific statute controls over a general one ‘without regard to priority of enactment’’’); see also b norman j. singer, sutherland statutes and statutory construction section . ( th ed. ). . morton, u.s. at – (‘‘where there is no clear intention otherwise, a specific statute will not be controlled or nullified by a general one, regardless of the priority of enactment.’’). tej. . . the electricity journal http://www.pacificorp.com/content/dam/pacificorp/doc/energy_sources/integrated_resource_plan/ irp/eeimodelingreportfinal- january .pdf http://www.pacificorp.com/content/dam/pacificorp/doc/energy_sources/integrated_resource_plan/ irp/eeimodelingreportfinal- january .pdf http://www.pacificorp.com/content/dam/pacificorp/doc/energy_sources/integrated_resource_plan/ irp/eeimodelingreportfinal- january .pdf http://www.pacificorp.com/content/dam/pacificorp/doc/energy_sources/integrated_resource_plan/ irp/eeimodelingreportfinal- january .pdf http://www.pacificorp.com/content/dam/pacificorp/doc/energy_sources/integrated_resource_plan/ irp/eeimodelingreportfinal- january .pdf http://www.pacificorp.com/content/dam/pacificorp/doc/energy_sources/integrated_resource_plan/ irp/eeimodelingreportfinal- january .pdf http://pjm.com/~/media/documents/other-fed-state/ -epa-hq-oar- - -iso-rto.ashx http://pjm.com/~/media/documents/other-fed-state/ -epa-hq-oar- - -iso-rto.ashx http://pjm.com/~/media/documents/other-fed-state/ -epa-hq-oar- - -iso-rto.ashx http://pjm.com/~/media/documents/other-fed-state/ -epa-hq-oar- - -iso-rto.ashx http://pjm.com/~/media/documents/other-fed-state/ -epa-hq-oar- - -iso-rto.ashx http://energy.senate.gov/public/index.cfm% ffuseaction=pressreleases.detail% pressrelease_id= c -c aa- c - - a a bff % month= % year= % party= http://energy.senate.gov/public/index.cfm% ffuseaction=pressreleases.detail% pressrelease_id= c -c aa- c - - a a bff % month= % year= % party= http://energy.senate.gov/public/index.cfm% ffuseaction=pressreleases.detail% pressrelease_id= c -c aa- c - - a a bff % month= % year= % party= http://energy.senate.gov/public/index.cfm% ffuseaction=pressreleases.detail% pressrelease_id= c -c aa- c - - a a bff % month= % year= % party= http://energy.senate.gov/public/index.cfm% ffuseaction=pressreleases.detail% pressrelease_id= c -c aa- c - - a a bff % month= % year= % party= http://energy.senate.gov/public/index.cfm% ffuseaction=pressreleases.detail% pressrelease_id= c -c aa- c - - a a bff % month= % year= % party= http://energy.senate.gov/public/index.cfm% ffuseaction=pressreleases.detail% pressrelease_id= c -c aa- c - - a a bff % month= % year= % party= http://dx.doi.org/ . /j.tej. . . 	walking the line between the clean air act and the federal power act: balancing emission reductions and bulk power reliability 	bulk power reliability and the federal power act 	doe&apos;s authority under the fpa 	ferc&apos;s authority under the fpa 	epa&apos;s authority under the clean air act to regulate power plants 	epa&apos;s authority under the caa 	national ambient air quality standards 	mercury and air toxics standards 	past conflicts between the caa and the fpa 	the potomac river generating station 	the california energy crisis 	potentially potent rulemakings 	epa&apos;s finalized regulations 	cross-state air pollution rule 	mats for utility generators 	epa&apos;s proposed regulations 	anticipated impacts on bulk power reliability 	potential outcomes for resolving reliability conflicts 	reliability safety valve 	presidential extensions 	compelled operation to protect bulk power reliability 	which statute controls if another conflict arises? editorial advanced nanomaterials for energy and environmental applications zhi chen, dantong zhou, xiao-ping dong, wei-hua shen, man-rong li, cristina della pina, and ermelinda falletta college of materials science and engineering, china jiliang university, no. xueyuan street, xiasha higher education district, hangzhou, zhejiang , china department of chemistry, school of sciences, zhejiang sci-tech university, second avenue, xiasha higher education zone, hangzhou , china school of chemical engineering, east china university of science and technology, meilong road, shanghai , china department of chemistry and chemical biology, rutgers, the state university of new jersey, taylor road, piscataway, nj , usa dipartimento di chimica inorganica, metallorganica e analitica, unità instm, università degli studi di milano, via venezian , milano, italy correspondence should be addressed to zhi chen; zchen @gmail.com received august ; accepted august copyright © zhi chen et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. the increasing of energy crisis and environmental pollution has drastically threatened the sustainable development of human being. lots of technologies, for instance, rechargeable batteries and supercapacitors, solar photovoltaic cells, solar photocatalysis, biomass fuels, efficient adsorption technol- ogy, and so forth, have been developed in the past decades to exploit clean energies and efficiently deal with pollutants. the key is to obtain advanced materials with superior structures and functions as active electrodes or efficient catalysts and adsorbents. also, it is fundamentally important to deeply understand the relationship between structure and proper- ties. this special issue is focused on synthesis and application of advanced nanomaterials for energy and environmental applications. z. chen and colleagues work on the loading of nanosized au in the channels of nanoporous nickel phosphate vsb- . co could be catalytically removed on the prepared catalyst at a lower temperature than that on zif- . enhanced catalytic activity could be observed after the first catalytic circle. the reaction mechanism has also been investigated and it was found that au +/au is responsible for the enhancement. s. peng et al. report the fabrication of ru nanoparticles on mesoporous silica by an in situ reduced method. the pre- pared sample could work as a highly efficient heterogeneous catalyst for h generation from the hydrolysis of an alkaline nabh solution. furthermore, the prepared catalyst could be reused and the residual catalytic activity of the repeated ru/hms still remains . % after runs. carbon nanotubes (cnts) have attracted attention in the last decade due to their prominent properties. g. allaedini and colleagues investigate the effect of alumina and mag- nesia supported ge nanoparticles on the growth of carbon nanotubes by using the chemical vapor deposition method. a tip-growth mechanism is proposed for the grown carbon nanotubes. the synthesized sample is confirmed as carbon nanotube by using tem, xrd, and raman techniques. it has also been found that the degree of graphitization of prepared cnts has a close relationship with the support. d. h. kim et al. investigated the selective catalytic reduction (scr) activity by using v o /tio as the catalyst. ce and w can work as the promoter for the scr process and the enhanced selectivity and activity have been observed. the scr reactivity at low temperature region and n selectivity hindawi publishing corporation journal of nanomaterials volume , article id , pages http://dx.doi.org/ . / / journal of nanomaterials at high temperature region could be improved by changing the impregnating order between w and ce precursors on v o /tio catalyst. various techniques have been used to analyze the synthesized samples. it was found that w- and ce-overloaded w/ce/v/tio ( : : wt%) catalyst shows the most remarkable de-nox properties over the wide tem- perature region and high n selectivity at high temperature region ( – ∘c). the mechanism of the superior activity has also been proposed. finally, g. santana rodŕıguez et al. reported their research on nanosized ytterbium stabilized zirconia (ybsz) thin films prepared by ultrasonic spray pyrolysis. the high conductivity is investigated and resulted from different phys- ical parameters in the films. all of these papers demonstrate how the advanced nano- materials have been constructed and have potential appli- cations in environmental control and development of new energy for the sustainable development of society. the editors hope that the readers of this special issue will benefit from designing and constructing novel advanced nanomaterials with applications in environmental control and new energy development. acknowledgments the editors would like to acknowledge the authors who have submitted their work to this special issue. the editors are grateful for all reviewers for their contribution to this special issue. the lead guest editor would like to thank all guest editors for spending their precious time in handling the paper. zhi chen dantong zhou xiao-ping dong wei-hua shen man-rong li cristina della pina ermelinda falletta submit your manuscripts at http://www.hindawi.com scientifica hindawi publishing corporation http://www.hindawi.com volume corrosion international journal of hindawi publishing corporation http://www.hindawi.com volume polymer science international journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume ceramics journal of hindawi publishing corporation http://www.hindawi.com volume composites journal of nanoparticles journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume international journal of biomaterials hindawi publishing corporation http://www.hindawi.com volume nanoscience journal of textiles hindawi publishing corporation http://www.hindawi.com volume journal of nanotechnology hindawi publishing corporation http://www.hindawi.com volume journal of crystallography journal of hindawi publishing corporation http://www.hindawi.com volume the scientific world journal hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume coatings journal of advances in materials science and engineering hindawi publishing corporation http://www.hindawi.com volume smart materials research hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume metallurgy journal of hindawi publishing corporation http://www.hindawi.com volume biomed research international materials journal of hindawi publishing corporation http://www.hindawi.com volume n a n o m a te ri a ls hindawi publishing corporation http://www.hindawi.com volume journal of nanomaterials [pdf] optimal photovoltaic system design with multi-objective optimization | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /ijamc. corpus id: optimal photovoltaic system design with multi-objective optimization @article{ibrahim optimalps, title={optimal photovoltaic system design with multi-objective optimization}, author={a. ibrahim and farid bourennani and s. rahnamayan and g. naterer}, journal={int. j. appl. metaheuristic comput.}, year={ }, volume={ }, pages={ - } } 	a. ibrahim, farid bourennani, + author g. naterer 	published 	computer science 	int. j. appl. metaheuristic comput. recently, several parts of the world suffer from electrical black-outs due to high electrical demands during peak hours. stationary photovoltaic pv collector arrays produce clean and sustainable energy especially during peak hours which are generally day time. in addition, pvs do not emit any waste or emissions, and are silent in operation. the incident energy collected by pvs is mainly dependent on the number of collector rows, distance between collector rows, dimension of collectors… expand view via publisher rahnamayan.ca save to library create alert cite launch research feed share this paper citationshighly influential citations background citations methods 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about semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue bicycle commuting in melbourne during the s energy crisis: a semiparametric analysis of intraday volumes melbourne business school from the selectedworks of michael stanley smith bicycle commuting in melbourne during the s energy crisis: a semiparametric analysis of intraday volumes michael s smith, melbourne business school goeran kauermann available at: https://works.bepress.com/michael_smith/ / https://mbs.edu/home https://works.bepress.com/michael_smith/ https://works.bepress.com/michael_smith/ / bicycle commuting in melbourne during the s energy crisis: a semiparametric analysis of intraday volumes michael s. smitha,� and göran kauermannb a melbourne business school, university of melbourne b department of business administration and economics, university of bielefeld th july to appear in the journal of transportation research part b: methodological � corresponding author; address for correspondence: professor michael smith, melbourne busi- ness school, university of melbourne, leicester street, carlton, vic , australia. email: mike.smith@mbs.edu abstract cycling is attracting renewed attention as a mode of transport in western urban environ- ments, yet the determinants of usage are poorly understood. in this paper we investigate some of these using intraday bicycle volumes collected via induction loops located at ten bike paths in the city of melbourne, australia, between december and june . the data are hourly counts at each location, with temporal and spatial disaggregation allowing for the impact of meteorology to be measured accurately for the first time. moreover, during this period petrol prices varied dramatically and the data also provide a unique opportunity to assess the cross-price elasticity of demand for cycling. over-dispersed poisson regression models are used to model volumes at each location and at each hour of the day. seasonality and the impact of weather conditions are modelled as semiparametric and estimated using recently developed multivariate penalized spline methodology. unlike previous studies that use aggregate data, the empirical results show a substantial meteorological and seasonal com- ponent to usage. they also suggest there was substitution into cycling as a mode of transport in response to increases in petrol prices, particularly during peak commuting periods and by commuters originating in wealthy and inner city neighbourhoods. last, we extend the approach to a multivariate longitudinal count data model using a gaussian copula estimated by bayesian data augmentation. we find first order serial dependence in the hourly volumes and a ‘return trip’ effect in daily bicycle commutes. key words: cross-price elasticity; discrete copula model; generalized mixed models; mode of transport; multivariate penalized spline smoothing; count data model. introduction cycling offers many advantages as a mode of transport in western society. these include zero marginal emissions of greenhouse gases and pollutants, reduced traffic congestion and numerous health benefits, including reduced rates of obesity; see pucher, dill & handy ( ) for extensive evidence on the health benefits of cycling. all of these are major contempo- rary issues, and it has lead to an increase in interest in the determinants of bicycle usage; for example, see rietveld & daniel ( ), wardman, tight & page ( ) hunt & abra- ham ( ) and heinen et al. ( ). to date, studies in the transportation literature have almost exclusively focused on the analysis of survey or experimental data which allow for the study of individual level factors on the decision to cycle; for example, see nankervis ( ), stinson & bhat ( ), shannon et al. ( ) and xing et al. ( ). analysis of data on cycling volumes that are aggregate with respect to individuals, but disaggregate over time and location, has not been attempted for two reasons. the first is a lack of appropriate data, while the second is the difficulty in controlling for the complex impact of weather conditions. this paper addresses both problems by exploiting a new and unique source of data, and by employing multivariate penalized spline smoothing to account for the impact of meteorology and seasonality. we analyse hourly cycling volumes at ten locations on dedicated bicycle paths in the city of melbourne in australia. these locations have been selected to provide an accurate picture of inner-city bicyle commutes and are collected automatically using recently installed induction loops placed under each path; in this sense the data are both comprehensive and highly accurate. we examine hourly cyclist counts from december to june , which corresponds to a period in which oil prices experienced extreme levels of volatility and finishes just before the peak of us$ . per barrel on july . as a result, during this period these counters have been installed by vicroads and they believe these count the number of cyclists who pass over them with over % accuracy. this is the all time peak at the time of writing. average melbourne unleaded petrol pump prices varied between a minimum of . cents per litre to . cents per litre. therefore, this data provides a unique opportunity to assess the cross-elasticity of the demand for cycling with respect to petrol prices. we model hourly counts using over-dispersed poisson regression models. each hour of the day is modelled separately, thereby controlling for the strong diurnal variation in all aspects of the model. such a separation is also common in the intraday modelling of demand for flow commodities, such as electricity (fiebig, bartels & aigner ; cottet & smith ). the mean of each poisson model contains linear effects for trend, day type and the logarithm of a measure of melbourne petrol prices, so that the corresponding cross-elasticity is constant. the effect of seasonality and intraday weather conditions are accounted for as semiparametric effects. while transport researchers suspect weather and seasonality affect the propensity to cycle in quite different ways than other modes of transport (heinen et al. ), to date there is only limited evidence to this effect. for example, nankervis ( ) and shannon et al. ( ) find minor and no weather effects, respectively, using limited datasets on australian univer- sity students. in our study, by matching hourly observations from local weather stations with those from the induction loops we find that both immediate weather conditions and season are major determinants of bicycle commutes. in each poisson model the impact of weather is modelled as an unknown multivariate function of six meteorological variables. we follow an approach advocated in the environmental (shively & sager ) and econometric (pana- giotelis & smith ) modelling literatures and simplify the effect as additive in univariate main effects and all pairwise bivariate interactions. this results in unknown univariate and bivariate functions which are estimated jointly using penalized spline smoothing. here, each function is modelled using a high-dimensional basis representation with unknown coef- ficients that are penalized with a quadratic penalty to ensure a smooth fit. such an approach has a long history in the statistical literature, see wahba ( ), wecker & ansley ( ) and o’sullivan ( ) for early examples, but has seen much recent attention and extension; see the overviews by ruppert, wand & carroll ( ; ) and wood ( ). we follow wahba ( ), wong & kohn ( ), wood ( ), wand ( ) and lang & brezger ( ) and interpret the penalties as gaussian prior distributions for the basis coefficients, so that the poisson model can be interpreted as a generalized linear mixed model (glmm). scalar ‘smoothing parameters’ control the level of smoothing of each function, and these can be estimated from the data using a marginalized penalized likelihood derived from a laplace approximation to the full penalized likelihood. the use of the laplace approximation in such contexts is justified asymptotically in kauermann, krivobokova & fahrmeir ( ) and rue, martino & chopin ( ). the use of approximations to a full likelihood function is increasingly popular when the full likelihood function is computationally intractable. for example, in the transportation literature ferdous et al. ( ) approximate the likelihood of a multivariate ordered probit model as a composition of bivariate ordered probit model likelihoods, which is easily maximized to provide a consistent estimator. following wager, vaida & kauermann ( ) we show how the marginalized likelihood can be used to com- pute a marginal akaike information criteria (aic). using this criteria we adopt a stepwise algorithm to identify spurious components in the additive decomposition of the meteoro- logical effect. the end result is a flexible, smooth and parsimonious representation of the multivariate effect of meteorology on cycling volumes that can be estimated joint with other aspects of the poisson model. only by carefully controling for the complex nonlinear impact of weather and season can reliable estimates of the cross-elasticities of demand with respect to petrol prices be obtained. we find that both over-dispersion and intraday serial dependence are present in the hourly volumes. to account for the latter we construct a -dimensional copula model for the longitudinal vector of hourly volumes during the day. copula models are multivariate models that can be constructed from arbitrary marginal models, with any dependence captured by a copula function. copula modeling is increasingly popular throughout the physical and social sciences, and has been employed previously in transport studies by bhat & eluru ( ) and sener et al. ( ). in our study the margins are the over-dispersed poisson regression models, while a gaussian copula function is used to account for the intraday dependence. the gaussian copula function is used here because it allows for both positive and negative dependencies between counts at all hours, and can be used in higher dimensions unlike many alternatives. the end result is a multivariate longitudinal poisson model for dependent counts, where the semiparametric exogenous effects have forms that vary over each hour. as highlighted by danaher & smith ( ) it is not widely appreciated that many existing latent variable based count models can be viewed as special cases of a copula model. for example, song ( ) expresses the multivariate probit model as a gaussian copula. similarly, the correlated count model of herriges et al. ( ) is an example of a gaussian copula model. as discussed in danaher & smith ( ) because the margins are discrete-valued, es- timation of the dependence parameters of the copula using direct maximum likelihood is computationally impractical for a -dimensional gaussian copula. we therefore follow pitt, chan & kohn ( ) and danaher & smith ( ) and estimate the gaussian copula us- ing data augmentation and bayesian markov chain monte carlo (mcmc). the approach of estimating the marginal models first, and then the copula parameters in a second step, is widely employed in the copula literature; see cherubini, luciano & vecchiato ( ) and silva & lopez ( ) for discussions. estimates of pairwise spearman correlations reveal strong first order serial dependence between the hourly volumes, along with additional de- pendence between volumes during the morning and evening commuting peaks. the latter is a ‘return trip’ effect evident in the counts, but caused at the individual level where people who commute by bicycle to work are more likely to return by the same mode of transport than would otherwise be the case. to show the flexibility of the copula model we compute the resulting distribution of total daily volumes for any given day, and also the forecasts of evening volumes given those observed in the morning. the paper continues by outlining the data, and then the over-dispersed poisson model. multivariate penalized splines are discussed, along with their interpretation as a generalized linear mixed model. we show how to estimate the smoothing parameters using the marginal- ized likelihood, which is derived in greater detail in appendix a. using the marginalized likelihood we also define the marginalized aic criteria. the intraday analysis of the effects of weather, season and petrol prices on bicycle commutes follow, along with an outline of the copula model and the rich intraday serial dependence structure uncovered. appendix b provides a summary of the bayesian mcmc scheme used to estimate the gaussian copula models, while a discussion concludes. data . bicycle usage in melbourne the cycling data we examine were obtained from vicroads, which is a branch of the state government of victoria. as well as responsibility for the management of the state road net- work, the organisation oversees other transport initiatives. these include the development and implementation of cycling programs throughout victoria, with the aim of increasing participation in cycling as part of an integrated transport network (austroads inc., ). melbourne is the capital of victoria, with a population of . million people in , which makes up . % of the state total. the city is located at the mouth of the yarra river with a flat geography which is well-suited to cycling, and possesses an extensive bicycle network. nevertheless, cycling is still only a minor mode of transport in melbourne, comprising only . % of total trips to work in (bonham & suh ), and the city has a high level of car dependency and a growing traffic congestion problem (clarke & hawkins ). from vicroads began to install inductive loop counters on off-road bicycle paths at key locations surrounding the melbourne central business district (cbd). these count bicycle volumes with a high degree of accuracy at an intraday level. we examine hourly counts of cyclists at the ten locations where loops were first installed and where the data is most complete. table lists these locations, along with the orientation of the location for further information visit their extensive website at www.vicroads.vic.gov.au. these are australian bureau of statistics estimates at june ; abs, ‘population by age and sex, regions of australia’ (abs cat. no. . ). in relation to the cbd and the direct line distance between the loop and the general post office (gpo) building located in the centre of the cbd. the number of bicycle trips is low both between : – : and during weekends, and we focus here only on weekday trips between : – : on working days, which are dominated by daily commutes. table lists mean hourly counts during these hours, and also broken down by the morning peak period : – : and evening peak period : – : . also listed are the number of observations and time frame over which the data are available. —–table about here—– . spatial variation melbourne has a radial transport network (clarke & hawkins ), and the loops have been located to count commuting trips to and from the cbd and immediate locale. there is a strong segmentation of the city suburbs into four quadrants radiating from the cbd, which roughly correspond to the four directions of the compass. this division is based upon topology, patterns of urban development and local government boundaries, and is associated with substantial differences in the socio-economic status of residents. the southern and eastern suburbs are more affluent than the northern and western suburbs, with average incomes of residents up to . % higher (abs ). each loop is located on an off-road cycle path which radiates between the cbd and from suburbs in one of the four quadrants, as listed in table . using this information, we create several aggregate counts based upon spatial location. the first two are based upon the direction of origin (the south and east suburbs, se, and the northern suburbs, n), while a third is for inner city loops (ic) closest to the cbd. in creating these counts, we exclude we exclude the annual ‘ride to work day’ and the days during the melbourne commonwealth games. the average total income of wage earners for the melbourne abs statistical regions are: western melb. $ , ; moreland city (inner north) $ , ; northern middle melb. $ , ; boroondara city (inner east) $ , ; eastern middle melb. $ , ; southern melb. $ , . the three loops with the highest proportion of missing data (numbers , and ), as well as omitting days where any of the component loops in the cumulative counts were missing. last, we also create a city-wide count (all) at the seven loops with the most complete data. summaries for these four cumulative counts are also provided in table . . seasonality and time of day figure contains boxplots of the hourly city-wide counts (all) broken down by both season and time of day. the four panels correspond to the southern hemisphere seasons of spring (september to november), summer (december to february), autumn (march to may) and winter (june to august). seasonal variation is apparent, with lower volumes being observed in winter compared to summer. counts vary strongly according to the time of day, and peak during the morning ( : – : ) and evening ( : – : ) commuting periods. —–figures and about here.—– . meteorology and cost of fuel even a cursory examination of this data reveal that meteorological conditions are a key determinant of bicycle commutes. for example, figure plots the hourly counts at the st georges road loop on the november in both and . both days were working weekdays, yet counts in were substantially lower than in . this is likely due to meteorological variation, with it being cool and raining between : and : on this day in , yet hot and dry on . the relationship between weather conditions and the propensity to cycle is indiscernible in previous studies that use either individual level survey data (shannon et al. ; hunt & abraham ), or data that is highly aggregated with respect to time or location (nankervis ; rietveld & daniel ). hourly data was obtained on meteorological variables from the australian bureau of mete- orology observed at the three melbourne metropolitan weather stations located closest to the loops. the variables considered were temperature (temp), humidity (hmd), windspeed (wind) and rainfall (rain). to account for a small number of missing observations, and minor spatial variation, we employ average measurements across the three stations. the manner in which meteorological conditions affect the decision to cycle to work (rather than switch to other modes of transport) is complex, and to help capture this we introduce two additional variables. the first is a measure of recent rainfall (rrain), which is the to- tal rainfall in the current and two previous hourly periods, while the second is the daily maximum temperature (mtemp). the petrol price data we examine are average weekly pump prices of unleaded petrol ob- served at retail outlets in the melbourne metropolitan region. unleaded petrol is by far the largest category of fuel sold in australia, and has a price that is almost perfectly correlated with that of other fuels, such as diesel, lpg and higher octane unleaded petrol. figure plots the average real weekly petrol price in july australian dollars (petrol) and the total weekday counts at all loops. the linear correlation between real petrol prices and total daily counts is statistically insignificant, with any relationship being hard to determine because of the very high variance in counts. last, we note here that while the automobile is by far the most popular mode of transport in melbourne, the city also has an extensive integrated public transport system with a single ticketing system. however, the real price of public transport usage remained constant during the period and we therefore do not include this in our model. —–figure about here—– the stations were essendon airport, viewbank and moorabbin airport. melbourne cbd was not used because its measurements are known to be unreliable due to the surrounding high rise buildings. this data are constructed by the australian monitoring organization fueltrac; see www.fueltrac.com.au. the price deflator used was the australian bureau of statistics quarterly consumer price index for all groups. prices were increased inline with inflation three times during the period: on january , june and january . modelling usage . poisson regression model we model counts separately at each hour of the day for each loop, or cumulative count. denoting yi as the ith observation of an hourly count, for i = , . . . ,n days, we employ an over-dispersed poisson regression model with moments e(yi|ηi) = μi = exp(ηi) , var(yi|ηi) = μiφ, ( . ) and φ ≥ an unknown dispersion parameter (wedderburn ). estimation is undertaken using the fisher scores (see mccullagh & nelder ; p. ) ỹi = ηi + (yi − μi)/μi , for i = , . . . ,n, ( . ) where e(ỹi) = ηi and var(ỹi) = φ/μi. following many previous authors we compute inference using quasi-maximum likelihood (qmle) assuming normality for ỹi, so that ỹi ∼ n(ηi,φ/μi). ( . ) fisher scoring proceeds iteratively by (i) calculating ỹ = {ỹ , . . . , ỹn} and (ii) fitting η = {η , . . . ,ηn} using the gaussian likelihood at equation ( . ) for given ỹ; see wolfinger & o’connell ( ) for a discussion. we model the mean as ηi = z ′ iα + s(ti) + m(xi) , ( . ) where zi is a vector of linear effects with coefficients α, s(ti) is a smooth seasonal effect with respect to the time of year ≤ ti < , and m(xi) is an unknown multivariate function of the six meteorological variables xi = (xi , . . . ,xi ). this is an extension of the generalized linear model (wood ; chapter ) to include flexible semiparametric components s and m. in the linear component we include an intercept, linear time trend, five day type dummy variables for tuesday to friday and for school holidays. we also include log(petrol), so that the cross-price elasticity of the mean ∂μi ∂petroli × petroli μi = αp is constant, resulting in a total of linear terms. while it is possible to also model the time trend as semiparametric, we do not do so because it would only be identifiable from the seasonal component by the smoothness parameter of s. similarly, the elasticity can also be modelled as semiparametric, but we do not do so here because it is both a weak effect, and is harder to interpret if nonlinear. the effect of weather upon counts is complex and highly nonlinear. to simplify the problem we assume additivity up to bivariate interactions between meteorological variables, so that m(xi) = ∑ j= mj(xij) + ∑ j= ∑ l>j mjl(xij,xil) , ( . ) where mj and mjl are univariate and bivariate smooth functions, respectively. similar ad- ditivity assumptions have been used to model the effect of meteorological variables upon ozone levels (shively & sager ) and intraday electricity demand (panagiotelis & smith ). the additive decomposition at equation ( . ) involves the estimation of unknown functions and we identify a more parsimonious representation in a data-based fashion. let i = { , , . . . , } be the index set of the meteorological variables. we denote with s ⊂ i the set of indices where mj are nonlinear functions, and with b = {(i,j); i �= j, i ∈ s, j ∈ s} the set of non-zero bivariate functions. further denoting the model m = {s, b}, we define a parsimonious representation of equation ( . ) as m(xi; m) = ∑ j∈i xijβj + ∑ j∈s mj(xij) + ∑ (j,l)∈b mjl(xij,xil). ( . ) . penalized splines we discuss determination of m in section . , but outline here how the unknown semi- parametric components in equation ( . ) can each be expressed as penalized splines for given m. we represent each unknown function as a linear combination of thin plate spline ba- sis terms (wahba , pp. – ), which also corresponds to the popular cubic smoothing spline basis for the univariate functions. we also use the same basis for the seasonal effect s in equation ( . ), but with periodicity enforced on the basis terms so that s( ) = s( ). the functions are therefore s(ti) = b̃s(ti) ′ṽs , mj(xij) = b̃j(xij) ′ṽj , and mjl(xij,xil) = b̃jl(xij,xil) ′ṽjl , ( . ) for j ∈ s and (j, l) ∈ b. the vectors b̃s, b̃j, b̃jl are bases evaluated at the ith observation, and ṽs, ṽj, ṽjl are coefficient column vectors for which we employ quadratic penalty terms. for the univariate functions, this penalty is equivalent to the integrated squared second order derivative of the function (wahba ; green & silverman , p. ). for the bivariate functions we penalize the sum of the integrated squared elements of the hessian matrix (wood ). the knots of the thin plate basis terms are located at all unique observations of the indepen- dent variables, so that there can be up to n terms in the basis. to reduce the computational burden we follow hastie ( ) and wood ( ) and employ low rank smoothing. for each function, this involves a spectral decomposition of the design matrix for the basis decompo- sition. the k eigenvectors corresponding to the k largest eigenvalues are used as a reduced rank basis, so that we redefine the functions in equation ( . ) as s(ti) = bs(ti) ′vs , mj(xij) = bj(xij) ′vj , and mjl(xij,xil) = xijxilβjl + bjl(xij,xil) ′vjl . ( . ) here, βjl is an unpenalized linear interaction coefficient and vs,vj,vjl are basis coefficient k-vectors for the reduced rank basis terms bs,bj,bjl. the reduced rank basis coefficients have quadratic penalties v′sdsvs, v ′ jdjvj and v ′ jldjlvjl, where ds,dj and djl are diagonal matrices containing the k largest eigenvalues for the spectral decomposition of each basis. such an approach is similar to that advocated by eilers & marx ( ), ruppert, wand & carroll ( ), lang & brezger ( ) and others who directly select k basis terms and an associated quadratic penalty with non-diagonal matrices. we follow wood ( , p. ) and set k = for the univariate functions and k = for the bivariate functions, and there is substantial evidence that selecting k larger has little influence on the fit; see ruppert ( ) or kauermann & opsomer ( ) for discussions. let λs,λj,λjl be smoothing parameters for functions s,mj,mjl, respectively. for model m, let θm denote both the basis term coefficients and linear terms for all components in equations ( . ), ( . ) and ( . ), and λm be the set of all smoothing parameters. then the penalized quasi-log-likelihood takes the form lp(θm,λm) = l(θm) − ∑ j∈s λjv ′ jdjvj − ∑ (j,l)∈b λjlv ′ jldjlvjl − λsv ′ sdsvs , ( . ) where l(θm) = ∑n i= li(θm) is the unpenalized quasi-log-likelihood from equation ( . ) for a given model m. conditional upon the smoothing parameters λm, maximization of equa- tion ( . ) with respect to θm can be undertaken via fisher scoring as discussed in section . . the estimation of λm and selection of m is discussed below. . generalized linear mixed model following wahba ( ), wong & kohn ( ), wood ( ) and others we interpret the penalties in equation ( . ) as gaussian priors for the reduced rank basis term coefficients, so that vs ∼ n( ,λ− s d− s ), vj ∼ n( ,λ− j d− j ) and vjl ∼ n( ,λ− jl d− jl ) , ( . ) thereby reformulating the problem as a glmm. estimation proceeds by maximizing the log- arithm of the marginal likelihood lm(α,βm,λm; m) obtained by integrating out the reduced rank basis coefficients. this integration can be undertaken based on the laplace approxima- tion as suggested by breslow & clayton ( ) and outlined in more detail in appendix a. asymptotic results supporting this approach in the penalized spline smoothing context can be found in kauermann, krivobokova & fahrmeir ( ) and rue, martino & chopin ( ). maximization of the laplace approximation of lm with respect to {α,βm,λm} is pursued as part (ii) of the fisher scoring algorithm outlined in section . using the standard steps for a linear mixed model (lmm) listed in harville ( ); also see appendix a for more details. re-calculation of ỹ , . . . , ỹn and refitting the lmm provide the essential steps of the fisher scoring algorithm. the smoothing parameters λm are reciprocals of prior variances which are estimated following optimisation. the procedure is implemented numerically in regular statistical software, where we make use of the ‘gamm’ procedure provided in the package ‘mgcv’ in the statistical language ‘r’. finally, the semiparametric function estimates can be computed via penalized least squares estimation of the basis term coefficients in equa- tion ( . ). the benefits for writing the model in the mixed model framework are twofold. first, we directly obtain estimates for the smoothing parameters λm, thereby enabling com- putation of the function estimates. second, we can also use the mixed model framework for model selection as discussed below. implementation of glmms and smoothing in r is discussed by wood ( ). . model selection the index set m = {s, b} determines the functional form of the meteorological effect m in equation ( . ), and we determine this from the data. we use the aic (akaike ) computed using the marginal likelihood; a criterion that is labelled marginal aic by vaida & blanchard ( ) and wager, vaida & kauermann ( ), and has been recently extended to glmms by lavergne, martinez & trottier ( ). for model m, let lm(α̂, β̂m, λ̂m; m) be the maximum of the logarithm of the (laplace approximation) to the marginal likelihood at step (ii) of the fisher scoring algorithm. then we define the marginal aic as maic(m) = − lm ( α̂, β̂m, λ̂m; m ) + q , ( . ) where q is the number of components (linear or nonlinear) in the model at equation ( . ). we could calculate maic for all possible models m, but we constrain the search strategy as follows. first, for numerical stability we do not consider models with bivariate effects in the pairs (rain,rrain) and (temp,mtemp) because they are highly correlated; the latter particularly during afternoon hours. second, to reduce the computational requirements, we use a stepwise algorithm to traverse the space of possible models. we start from the model s = { , . . . , } and b = ∅, and in the forward selection step we successively include components in b that reduce maic. in the backward selection step we successively reduce the smooth components in set s (but only those which are not also a component in b) if this reduces maic. empirical analysis . determinants of bicycle usage we estimate the poisson model for counts observed at all sites, and also for the four cumulative counts. substantial over-dispersion was found throughout, particularly during the evening peak period. for example, table reports the estimates of φ for all, which vary from a minimum of . at : to a maximum of . at : . table also reports the estimated time trends for the four cumulative counts. there is a strong underlying upwards trend in usage throughout the period, particularly during the morning and evening commuting periods and for trips originating from the northern and inner city suburbs. —–table about here—– table summarises the models identified with the maximum maic values for the cumu- lative count all at each time of the day. for each univariate meteorological variable we denote the linear effects with ‘l’ and nonlinear effects with ‘s’; non-zero bivariate interaction effects are denoted with ‘b’. a substantial degree of parsimony is identified, with only a few of the bivariate interaction effects non-zero, and many of the univariate components linear. similar parsimonious representations are also determined for the other count variables. during the early morning peak ( : – : ) the effect of meteorology is well represented as additive in the six univariate components, with a nonlinear mtemp effect throughout. figure plots the estimated meteorological effects for these three morning periods. the most important variables (as measured by function range) are mtemp, rain, rrain and wind, with the effects largely consistent during the three hours. interestingly, it is not current air temperature, but daily maximum temperature, which usually occurs later between : and : in melbourne, that proves important. in section . we also show that there is strong dependence between cycling volumes during the morning and evening peak commuting periods. this is likely to be induced by strong dependence between mode of transport choice for the commuting trips to and from the workplace. individuals therefore appear forward-looking in their decision-making and consider the forecast daily maximum temperature before selecting cycling as a mode of transport for the morning commute to work. a maximum temperature between and oc is optimum, with less bicycle trips undertaken when mtemp is outside this range. higher levels of recent rainfall rrain results in fewer cyclists; a similar effect is found with windspeed. confidence bands are also given for the estimates at : , which are similar to those for other times of the day. estimates of the functional forms of rain and rrain have wide confidence intervals because of the small proportion of non-zero observations ( . % and . %, respectively). during the evening peak period ( : – : ) the effects of current air temperature temp and recent rain rrain are both nonlinear and more pronounced than during the morning hours. this is likely because individuals are more backward-looking in their choice of mode of transport for the return commute. figure plots the nonlinear effects for the main evening commuting hour of : , including the seasonal component. recent rain has a substantial negative impact on propensity to cycle, whereas current rain has a linear coefficient with a p-value of . ; again, suggesting individuals are more backward-looking in their decision- making process. windspeed is still important, but is now linear with a negative coefficient and p-value of . . overall, while the impact of meteorology on bicycle commuting is complex, there are some main observations. cyclists are deterred by maximum temperatures outside the comfortable region of – oc, high windspeeds and rainfall. however, in the morning they anticipate the weather conditions for the rest of the day because once they have made the decision to cycle to work, they are more likely to return by this mode of transport. in the evening, they are more backwards-looking and make the decision to cycle partially based upon the weather conditions revealed during the day. —–table and figures and about here—– . cross-price elasticities table provides the estimated elasticities α̂p for all loops at all times of the day. four loops stand out as having significantly positive elasticities during the high volume commuting periods. these are loops , , and , which are all inner city loops and include two of the three highest volume loops in the data. this suggests that higher petrol prices are associated with an increase in bicycle trips recorded at these loops, presumably as commuters substitute from driving to cycling. we note that loop has negative elasticities during the commuting period. this loop is located on the beachfront . km away from the cbd and is likely to have the highest proportion of recreational trips. these are likely to have quite different determinants of usage than the commuting trips that are predominantly counted by the other loops. to examine further the spatial variation in elasticities, table provides the estimated elasticities for the cumulative counts at different times of the day. there is some evidence that commuters from the less affluent northern suburbs (n) are switching into cycling as a mode of transport as petrol prices rise, particularly in the early morning. however, there is stronger evidence that this is occuring during both the morning and evening commuting peaks with cyclists from wealthier suburbs (se). the largest spatial variation in elasticities is associated with the distance of the loop from the city centre, with positive elasticities at all hours of the day for inner city (ic) loops that are significant throughout commuting hours. presumably this is because cycling is a more attractive alterative to driving for trips to and from inner city suburbs and the cbd. this is consistent with xing et al. ( ) who find shorter trip distance is a key factor for higher rates of adoption of bicycle transportation in six small us cities. on a city-wide basis there is a meaningful petrol price effect with all elasticities being positive for the cumulative count all, which are significant during the commuting periods. to benchmark these results, we also estimate a log-linear model with the same mean struture and in the same manner, but without fisher scoring. the estimated elasticities are also found in table and they coincide with those from the poisson model. —–tables and about here—– . diagnostics to assess the fitted models we employ the standardised pearson residuals 	̂i = (yi − μ̂i)/ √ μ̂iφ̂ for i = , . . . ,n, where μ̂i and φ̂ are the point estimates from the best model m identified using maic. following equation ( . ) the residuals should be approximately standard normal. quantile plots suggest this to be the case and table contains p-values for the kolmogorov-smirnoff test of normality of the residuals for all cumulative counts at all times of day. the hypothesis that the residuals are standard normal can only be rejected at the % significance level in one of the circumstances, suggesting the over-dispersed poisson model is well-calibrated to the data. to quantify the proportion of variation explained we use the statistic r full = − n∑ i= 	̂ i / n∑ i= 	̂ i , where 	̂ i are the standardised pearson residuals in the null model with intercept only. to assess the relative influence of different components we calculate the r statistic using partial residuals on the numerator; that is, the residuals obtained from a fit when excluding specific components from ηi. the resulting full and partial r statistics are shown in figure for the four cumulative counts where we exclude (i) trend and season; (ii) day type; (iii) petrol price; and (iv) meteorological components. the model explains around - % of the variation in counts during peak hours, and - % of variation during the midday period. the meteo- rological effects dominate, particularly during the midday period, followed by the seasonal and day type components. petrol prices are the weakest of the four effects, and it would be difficult to determine its impact at an intraday level without controlling for the other effects. —–table and figure about here—– intraday serial dependence . copula model to account for intraday serial dependence in the counts we construct a multivariate model with m = dimensions, each corresponding to an hourly count. we employ a gaussian copula to capture dependence between the counts, and use the estimated hourly poisson re- gression models as the marginal distributions. for hour j and observation i, an over-dispersed poisson regression model with moments specified at equation ( . ) has a closed form prob- ability mass function pr(yij = yij) = fij(yij; μij,φj) given in cameron & trivedi ( ). the joint distribution function of all counts is f(yi , . . . ,yim) = Φm(Φ − (ui ), . . . , Φ − m (uim); c) = Φm(y � i , . . . ,y � im; c) . here, Φm is the distribution function of an m-dimensional gaussian distribution with zero mean and correlation matrix c, while Φ is the distribution function of a standard uni- variate normal. we stress here that adopting a gaussian copula model does not mean the counts are normally distributed; instead they follow a multivariate discrete distribution where the matrix c captures the dependence between the margins. as discussed in danaher & smith ( ), because the marginal distributions are discrete, y�ij is only known up to the bounds Φ− (fij(yij − ; μij,φj)) < y�ij < Φ− (fij(yij; μij,φj)) . ( . ) the bounds can be computed using the estimates of the marginal parameters μij,φj, count data yij and the marginal distribution functions fij(yij; μij,φj) = ∑yij w= fij(w; μij,φj). cameron & trivedi ( ) define a specific poisson-gamma mixture model which they call ‘negative binomial type ’ which has the moments of an over-dispersed poisson model. this is not to be confused with the regular negative binomial model that cameron & trivedi call ‘negative binomial type ’. estimation of a gaussian copula model with discrete margins is known to be a challenging problem (song ). direct maximum likelihood is computationally infeasible because evaluating the log-likelihood function is an o( m) operation, which is impractical for m = . however, pitt, chan & kohn ( ) and danaher & smith ( ) outline bayesian analyses based on mcmc sampling schemes that treat y� = {y�ij; i = , . . . ,n,j = , . . . ,m} as latent and generate their values explicitly, along with the correlation matrix c. such an approach is widely called ‘bayesian data augmentation’, and is popular for the estimation of multivariate probit models (chib & greenberg ). we summarise the method in appendix b, but refer the reader to danaher & smith ( ) for a complete discussion. . empirical analysis we estimate the gaussian copula for the cumulative count all in table using the bayesian method discussed above. because the copula model specifies the complete dis- tribution f , a wide range of output can be obtained from the fitted parametric distribu- tion to assess the level and impact of intraday serial dependence in the counts. danaher & smith ( ) outline how to compute pairwise spearman’s correlations ρsj,k = e(uijuik)− between counts yij and yik, where the expectation is evaluated with respect to the posterior distribution of c and y�. figure (a) plots the spearman correlations between all pairwise combinations of the hourly counts. positive dependence ρsj,j+ can be seen between adjacent hours j and j + . this first order serial dependence is likely due to the omission from the model for μij of additional determinants of usage that are themselves serially dependent. interestingly, there is also positive dependence between trips in the morning and evening peaks periods. for example, the correlation between the peak hours of : (j = ) and : (j = ) is ρs , = . . this is evidence of a ‘return trip’ effect, where individuals who have already commuted to work by bicycle in the morning are more likely than otherwise would be the case to also return by bicycle, rather than switch to another mode of transport. to illustrate the extent of this return trip effect, we compute the expected count during the evening peak at : , conditional upon that in the morning peak at : . that is, e(y ,i|y ,i) = ∫ e(y ,i|y ,i,y�,c)π(y�,c|data)d(c,y�), where (y�,c) is integrated out with respect to the posterior distribution π(y�,c|data). figure (b) plots this for and april , and on both days there is a strong positive relationship between morning and expected evening counts. the observed total daily counts for and april are plotted as vertical lines on figure (d). also plotted is the distribution of total daily counts ytotali = ∑ j= yij from the fitted copula model for both days, and the actual observations are within the support of the distribution. on april the total count was was high at , but was much less on april at a low of . the reason is the advent of bad weather on april, particularly with the strongest winds observed during the entire sample period. the average windspeed between : and : was . km/h and was . km/h during the entire hours. last, figure (c) plots the posterior mean of the partial correlation matrix arising from c. these are the partial correlations of the latent variables y�i = (y � i , . . . ,y � im) and again suggests strong first order intraday serial dependence. discussion this paper presents an empirical study of bicycle commuting in a major western urban environment that is typical of many of today’s car-dependent western cities. the data are unique in that they are both spatially disaggregate and, in particular, observed intraday. previous studies are either based on survey data or highly aggregated with respect to time and/or location, which makes it hard to account for the impact of meteorology. this can result in the misnomer that weather conditions are a minor factor in the decision to cycle (nankervis ; hunt & abraham ; wardman et al. ), whereas our empirical work finds otherwise. this is evaluated in a monte carlo fashion by simulating iterates from the copula model at each sweep of the sampling scheme, which is fast for a gaussian copula; see danaher & smith ( ). our analysis confirms a strong diurnal variation in all aspects of the model, with sharp differences between the morning peak, evening peak and intermediate hours. we find that meteorological conditions are the strongest determinant of bicycle volumes throughout most of the day, followed by season and day type. the form of the effect is a complex mul- tivariate function of six key meteorological variables, which are represented here using a parsimonious penalized spline decomposition. there is evidence that morning commuters are more forward-looking with regards to weather conditions, and evening commuters more backward-looking. the extreme volatility in petrol prices between and also provides something akin to a natural experiment, allowing estimation of the cross-elasticities. in response to high petrol prices we find significant substitution into cycling as a mode of transport in the inner city, wealthy neighbourhoods and in the city overall, particularly during the peak commuting periods. as far as we are aware, the results in this study provide the first non-anecdotal evidence of such a phenomena in a major western urban environment. this relationship would be difficult to ascertain without controlling for season and weather conditions in a flexible fashion at an intraday resolution. the results suggest that policies aimed at encouraging bicycle commutes have a higher chance of success when the price of petrol is high, and in an inner city environment, where commuting trips are of shorter distance. using a gaussian copula the model is extended to a multivariate model for longitudinal count data. unsurprisingly, there is strong serial dependence in the hourly counts. more interestingly, even though the data is aggregate with respect to individuals, the results sug- gest a return trip effect at the individual level. if someone commutes to work in the morning by bicycle, then the late afternoon commute is more likely to also be by bicycle than would otherwise be the case. by fitting a copula model a range of additional inference is also avail- able. this includes intraday forecasts of expected evening peak volumes, conditional upon those observed in the morning peak. such forecasts have potential in transport management systems. last, we reiterate here that a two-stage estimator is used in section . the first stage employs an approximate marginalized likelihood approach for estimating complex semipara- metric count data models for each hour. the second stage is a bayesian method to estimate a gaussian copula to provide a -dimensional multivariate count data model. because no strong priors are adopted, estimates based on the posterior distribution are very similar to those based only on the likelihood function, the latter of which cannot be employed directly because it is computationally intractable. our approach is therefore analogous to two-stage maximum likelihood, which is a popular approach for the estimation of copula models (cheru- bini et al. ). fully bayesian estimation, such as that employed in herriges et al. ( ) of a linear demand system using multivariate count data, is difficult because of the com- plexity of also undertaking multivariate smoothing. to achieve this, it would be necessary to embed bayesian multivariate smoothing methodology, such as that suggested by wong & kohn ( ), smith & kohn ( ), lang & brezger ( ) or panagiotelis & smith ( ), within the discrete-margined gaussian copula framework, which is difficult computationally. acknowledgments the work of michael smith was partially supported by australian research council grant dp , while göran kauermann acknowledges support provided by the deutsche forschungs- gemeinschaft (dfg, project “funktionale modelle bei zeitstrukturierten daten”). the au- thors would particularly like to thank vicroads for providing the bicycle usage data. they would also like to thank andrew john, doug dow and participants at a melbourne business school seminar for useful comments. a appendix in this appendix we provide further details on how to compute the marginal likelihood and estimate the glmm in section . . we write the log-likelihood contributions li(θm) in equation ( . ) in terms of the deviance (see mccullagh & nelder, , p. ), so that li(θm) = −d(yi,μi)/( φ), where d(y,μ) = − ∫ μ y (y − u)/u du and μi is the mean in equa- tion ( . ). for a given model m, we denote the concatenated design matrix of the nonlinear terms from the reduced rank bases as bm, and the corresponding concatenated basis co- efficients as vm. the prior vm ∼ n( ,d− m ), where dm is a block diagonal matrix with diagonal matrices λsds, λjdj, j ∈ s, and λjldjl, (j, l) ∈ b upon the leading diagonal. the logarithm of the marginal likelihood is lm(α,βm,λm; m) = log ∫ exp { − φ ∑ i d(yi,μi) } ψ(vm,d − m)dvm , (a. ) where ψ(x,v ) denotes the multivariate normal density with zero mean, variance matrix v evaluated at point x. the integral in equation (a. ) is not tractable analytically, which has led to the use of the laplace approximation; see breslow & clayton ( ). rue et al. ( ) show that this laplace approximation works well when computing posterior inference, while kauermann et al. ( ) demonstrate the effectiveness of the laplace approximation in penalized spline smoothing. applying the laplace approximation yields lm(α,βm,λm; m) ≈ − log |i + b′mm�bmd− m | − φ ∑ i d(yi,μ � i ) − v�m ′dmv � m . (a. ) here, m� = diag(μ� , . . . ,μ � n), μ � i = exp(z ′ iα + x̃ ′ iβm + b ′ m,iv � m), x̃i are the linear terms from the basis expansions, b′m,i is the ith row of bm and v � m is the maximizer of the last two components in equation (a. ). the deviance is approximated using the squared pearson residuals (yi −μ�i ) /μ�i as suggested in pierce & schafer ( ), see also mccullagh & nelder ( , p. ). note that (yi − μ�i )/μ�i = ỹi − log(μ�i ), with ỹi the fisher score defined in equation ( . ). the pearson residuals can be used to further approximate the (maximized) logarithm of the marginal likelihood (see breslow & clayton, or wolfinger & o’connell, ) as lm(α̂, β̂m,λm; m) ≈ − log |vm| − (ỹ − zα̂ − xβ̂m)′v − m (ỹ − zα̂ − xβ̂m) , (a. ) where vm = (m�− +bmdmb′m), z is a design matrix with ith row zi and x is the design matrix for the linear terms in the basis decomposition of functions s and m. maximization of equation (a. ) with respect to λm provides the final maximized value of the marginal likelihood. b appendix in this section we outline the data augmentation approach used to estimate the gaussian copula. this involves constructing a markov chain monte carlo sampling scheme to eval- uate the posterior distribution of the copula parameter matrix augmented with the latent variables, π(c,y�|data). we follow danaher & smith ( ) and employ the decomposition c = diag(Σ)− / Σ diag(Σ)− / , where Σ is a positive definite matrix, and diag(Σ) a diagonal matrix comprised of the leading diagonal of Σ. we further decompose Σ− = r′r, with r = {rij} being an upper triangular cholesky factor with leading diagonal elements all ones. the sampling scheme is: sampling scheme step . for j = , ...,m and i = , . . . ,n: generate from y�ij|{y�\y�ij},c, data. step . for i = , . . . ,m − , and j > i: generate from rij|{r\rij},y� using random walk metropolis-hastings. step . compute c from r. the distribution in step is a constrained normal distribution, and is given in danaher & smith ( ), along with the metropolis-hastings acceptance ratio for step . the sampling scheme is run for many sweeps, and after convergence, a monte carlo sample from the posterior distribution is obtained. from this sample parameter estimates and other posterior inference can be constructed. references akaike, h., . a new look at the statistical model identification. ieee transactions of automatic control, ( ), – . australian bureau of statistics, . national regional profile (by statistical local area). viewed sept. , www.abs.gov.au. austroads inc., . the australian national cycling strategy - 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(c a rl to n ) . k m n o rt h . . . d ec j u n . u p fi el d r a il w a y l in e . k m n o rt h . . . d ec j u n . c a p it a l c it y t ra il (p ri n ce s h il l) . k m n o rt h . . . d ec j u n . f o o ts cr a y r o a d p a th . k m w es t . . . d ec j u n . t ra m t ra il . k m s o u th . . . d ec j u n . b a y t ra il (s t. k il d a ) . k m s o u th . . . d ec j u n . c u m u la ti v e c o u n ts o v e r m u lt ip le l o o p s n n o rt h (l o o p s - ) . . . d ec j u n . s e s o u th & e a st (l o o p s - , , ) . . . d ec j u n . ic in n er c it y (l o o p s , - , ) . . . d ec j u n . a l l a ll l o ca ti o n s (l o o p s , , - , , ) . . . d ec j u n . t a b le : l o ca ti o n a n d sp a ti a l ch a ra ct er is ti cs o f in d u ct iv e lo o p co u n te rs , a v er a g e w o rk in g d a y h o u rl y co u n ts , a n d th e ti m e fr a m e a n d d a ta a v a il a b il it y fo r w o rk in g d a y s. s u m m a ri es a re g iv en fo r a ll te n lo o p s, a n d a ls o fo r cu m u la ti v e co u n ts o v er m u lt ip le lo o p s. t h e p er ce n ta g e o f m is si n g is re la ti v e to th e le n g th o f d a ta , a n d a n o b se rv a ti o n is co n si d er ed m is si n g fo r a cu m u la ti v e co u n t w h en o n e is m is si n g a t a n y co m p o n en t lo o p . h o u r e st im a te d t re n d c o e ffi c ie n ts fo r c u m u la ti v e c o u n ts s e . * * . * * . * * . * * . - . - . * - . * * - . * * - . * * - . . * * . - . n . * * . * * . * * . * * . * * . * * . * * . * * . * * . * * . * * . * * . * * . * * ic . * * . * * . * * . * * . * * . * . - . - . . . * . * * . * * . * * a l l . * * . * * . * * . * * . * * . - . - . * - . * * . . * . * * . * * - . * e st im a te d o v e r- d is p e rs io n p a ra m e te r φ fo r a l l . . . . . . . . . . . . . . t a b le : e st im a te d li n ea r tr en d s (a n n u a li ze d ) fo r th e lo g a ri th m o f th e m ea n co u n t η i = lo g (e (y i) ) d efi n ed in s ec ti o n . . v a lu es si g n ifi ca n t a t th e % le v el a re d en o te d w it h ‘∗’ , w h il e th o se si g n ifi ca n t a ft er a b o n fe rr o n i a d ju st m en t fo r th e h o u rs o f th e d a y a re d en o te d w it h ‘∗∗ ’. a ls o re p o rt ed a re th e es ti m a te s o f th e o v er -d is p er si o n p a ra m et er φ fo r th e cu m u la ti v e co u n t a l l . hour univariate effects temp l l l l s s l l l l s s s s mtemp s s s s s s s s s s l s s s rain s s s s s l s l l s l l l l rrain l l l l l s l l l l s s s s hmd l l l l l s s s l l l s l l wind l s s s s s s s s s l l l s bivariate interaction effects temp & wind . . . . . . . . . . . . . b mtemp & rain . . . . b . . . . . . . . . mtemp & hmd . . . . . b . . . . . . . . mtemp & wind . . . b b b . . b b . . . . rain & wind . . . . . . b . . . . . . . hmd & wind . . . . . . b b . . . . . . table : meteorological effects selected for the cumulative count all. univariate effects labelled with ‘l’ or ‘s’ were identified as linear or nonlinear, respectively. bivariate interac- tion effects identified as zero are labelled with ‘.’, and non-zero with ‘b’. omitted bivariate interactions were zero at all times of the day. h o u r m o rn in g p ea k ( : - : ) e v e n in g p ea k ( : - : ) l o o p n o . * . . - . * . . * * . . . * . * * . * * . * . . . * . - . * * - . . . . - . * - . - . * * - . . . - . . * * . * * . * * . * * - . . . . . * . * . * * . * * . * * . * * - . * - . . * * - . . - . - . - . - . - . - . . . * . * . * . - . . . . * . * - . . * . . * * . . . . * . - . . - . . . . - . - . * - . * . . - . . * * . * * . * . * * . . . . . . . . - . * - . . * * . * * . . * . . - . . . . * * . * . * * . * * - . - . . * * . * . * . . . * . . * . . * * . * * . * * . - . * * - . * * - . * * - . . . . - . . . - . - . * * - . * - . * * t a b le : e st im a te s o f α p , th e cr o ss -e la st ic it y w it h re sp ec t to p et ro l p ri ce s, u si n g th e p o is so n m o d el fo r a ll te n lo o p s a n d ti m es o f th e d a y. v a lu es si g n ifi ca n t a t th e % le v el a re d en o te d w it h ‘∗’ , w h il e th o se si g n ifi ca n t a ft er a b o n fe rr o n i a d ju st m en t fo r th e h o u rs o f th e d a y a re d en o te d w it h ‘∗∗ ’. h o u r m o rn in g p ea k ( : - : ) e v e n in g p ea k ( : - : ) c o u n t p o is so n m o d e l n . * * . . . * . . . . . - . . . - . . s e . . * * . * * . * . . . . . . . * * . * * . * * . ic . * * . * * . * * . * * . . * . * . . * . * . * * . * * . * * . * * a l l . * . * * . * . * . . * . . . * . . * * . * * . * . c o u n t l o g -l in ea r m o d e l n . * * . * . . . . . * . . * . . . - . . s e . . * * . * * . * * . . . * . . . . * * . * * . * * . ic . * * . * * . * * . * * . . * . * . * . * * . * . * * . * * . * * . * a l l . * . * * . * . * . . * . * . . * . . * * . * * . * . t a b le : e st im a te s o f th e cr o ss -e la st ic it y w it h re sp ec t to p et ro l p ri ce s u si n g th e p o is so n m o d el fo r th e fo u r cu m u la ti v e co u n ts . v a lu es si g n ifi ca n t a t th e % le v el a re d en o te d w it h ‘∗’ , w h il e th o se si g n ifi ca n t a ft er a b o n fe rr o n i a d ju st m en t fo r th e h o u rs o f th e d a y a re d en o te d w it h ‘∗∗ ’. h o u r l o ca ti o n n . . . . . . . . . . . . . . s e . . . . . . . . . . . . . . ic . . . . . . . . . . . . . . a l l . . . . . . . . . . . . . . t a b le : t h e p -v a lu es fo r k o lm o g o ro v -s m ir n o ff te st o f n o rm a li ty fo r th e st a n d a ri ze d p ea rs o n re si d u a ls . h o u r counts h o u rl y c o u n ts , s p ri n g h o u r counts h o u rl y c o u n ts , s u m m e r h o u r counts h o u rl y c o u n ts , a u tu m n h o u r counts h o u rl y c o u n ts , w in te r figure : hourly city-wide count (all) broken down by both time of day and southern hemisphere season. : : : : : : : : time of day h o u rl y v o lu m e tues nov wed nov figure : plot of hourly volumes at the st georges road inductive loop between : and : . the blue line depicts the counts on november , while the red line depicts the counts on november . ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ●● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ●● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ●● ●● ● ● ● ● ● ● ● ●● ● ●● ● ●● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ●● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ●● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ●● ● ● ● ●●● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ●● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ●● ● ● ● ● ● ● ●● ●● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ●● ● ● ● ● ● ●● ● ● ● ● ● ●● ● ● ● ● ● ● ● ●●●● ● ● ● ● ● ●●● ● ●● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●●● ● ● ● ● ● ● ● ● ●● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ●● ●● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ●● ● ● ● ●● ●● ● ● ● ● ●● ● ● ● ● ● ● co u n ts total bike counts (weekdays) . . . p ri ce in a u d average weekly ulp price figure : total daily counts across all loops and average metro petrol prices in melbourne between december and june . − . . . temp (degree centigrade) m (t e m p ) (a) − . . . mtemp (degree centigrade) m (m t e m p ) (b) . . . . . . − . . . rain (mm/hour) m (r a in ) (c) . . . . . . − . − . . . . rrain (mm/hour) m (r r a in ) (d) − . . . hmd (%) m (h m d ) (e) − . . . wind (km/h) m (w in d ) (f) figure : estimated meteorological effects for the cumulative count all during the morning peak period. the estimates are for : (solid line), : (dashed lines) and : (dotted lines). the shaded areas are % confidence bands for the estimates at : . − . − . . . . d a y o f ye a r s(day of year) (a ) − . − . . . t e m p ( d e g re e s ce n tig ra d e ) m(temp) (b ) − . − . . . m t e m p ( d e g re e s ce n tig ra d e ) m(mtemp) (c ) . . . . − . − . . . r r a in ( m m /h ) m(rrain) (d ) − . − . . . h m d ( % ) m(hmd) (e ) figure : estimated nonlinear effects for the cumulative count all at : , along with % confidence bands for the function estimates. the distribution of the independent variables are indicated on the horizontal axes. . . . . . . hour r .s q u a re location: n season wday petrol meteorological . . . . . . hour r .s q u a re location: se season wday petrol meteorological . . . . . . hour r .s q u a re location: ic season wday petrol meteorological . . . . . . hour r .s q u a re location: all season wday petrol meteorological figure : r plots for the four cumulative counts n, se, ic and all against time of day. the statistic r full is plotted as hollow circles, while the partial r values are given as different line types for models excluding (i) seasonal component s (bold); (ii) day of week dummies (long dashed); (iii) meteorological effects m (dot-dashed); and, petrol price term αp (small dots). hourly count h o u rl y c o u n t (c) . . . . . . . . . hourly count h o u rl y c o u n t (a) . . . . . . . . . . x − total daily count p ro b a b ili ty (d) (b) e (y |y ) y april april april april figure : bayesian posterior inference from the fitted gaussian copula model, with poisson regression margins, for the hourly observations of the cumulative count all. panel (a): matrix of pairwise spearman correlations ρsj,k. panel (b): expected evening peak count at : (j = ), conditional upon the morning peak count at : (j = ). panel (c): partial correlations from the copula parameter matrix c. panel (d): distribution from the copula model of total daily counts, ytotali , on april and , . 	melbourne business school 	from the selectedworks of michael stanley smith 	 	bicycle commuting in melbourne during the s energy crisis: a semiparametric analysis of intraday volumes 	bike.dvi the causes of the economic crisis econstor make your publications visible. a service of zbw leibniz-informationszentrum wirtschaft leibniz information centre for economics bratenstein, roger; fischer, manfred article — digitized version the causes of the economic crisis intereconomics suggested citation: bratenstein, roger; fischer, manfred ( ) : the causes of the economic crisis, intereconomics, issn - , verlag weltarchiv, hamburg, vol. , iss. , pp. - , http://dx.doi.org/ . /bf this version is available at: http://hdl.handle.net/ / 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exercise further usage rights as specified in the indicated licence. www.econstor.eu portugal the causes of the economic crisis by dr roger bratenstein and dr manfred fischer the authors are attempting an objective elucidation of the economic crisis in portugal. they are dealing with the influence of excess investment, with external economic factors such as the energy crisis and the recession in the industrial countries, and with the consequences of the revolutionary process. r apidly rising unemployment, inflation and bal- ance of payments difficulties have been among portugal's troubles since the middle of . that a great deal is being written about portugal at present has not been of much help in bringing the country's problems closer to a solu- tion. this is probably because through ideological shortsightedness the changes and developments of the last few years are often given a partisan interpretation. but neither the market economic system as such nor the limited nationalization measures nor fascism or foreign forces can be blamed entirely for the crisis. a tangle of causes is at the root of the crisis. its individual compo- nents are to be examined here in some detail. explanation by the excess investment theory the mistakes which were committed in the final stage of the caetano regime are often treated too indiscriminately in the current debate. talk of unscrupulous exploitation of the workers and in- competence of the dictators who turned portugal into the "poorhouse of europe" does not tally with the fact that the time before the revolution of april , , especially since the late sixties, was one of rapid economic growth and steadily increasing investment ( . p.c. of gnp in ; p.c. in ). the real national product rose by over p.c. in - (especially from onwards), and the boom continued during . a large monetary expansion occurred at the same time. the amount of central bank money increas- ed considerably because of the big rise from onwards in the central bank's currency reserves owing to larger earnings from tourism and remit- tances from a growing number of emigrants. meanwhile the balance of trade stayed in deficit. the inflationary effect of the external factors which could have been avoided only by a revalua- tion of the escudo was magnified by the grant of big loans to the commercial banks by the bank of portugal in and when the central bank might have reduced the liquidity in the econ- omy by restrictive open-market sales or similar measures. the commercial banks used the two- fold liquidity influx for a large expansion of their credit business; their deposits doubled between and . liquidity and credits - item i i i growth of total money circulation (in p.c.) . . . increase in central bank currency r e s e r v e s (in esc. mn) , , , increase in the banknote circulation (in esc. mn) , , , increase in central bank credits to commercial banks (in esc. mn) growth of commercial bank lendings (in p.c.) . . . s o u r c � : etudes economiques: portugal, published by oecd, paris, july . the consequence was an accelerating inflation- ary development, especially in the second half of . the wholesale prices rose between march and march by p.c., and the cost of living went up by p.c. between may and may . the wages could not keep in step with this trend and therefore fell in real terms from . to give an example, the purchasing power of industrial wages in lisbon declined, after ad- justments for the rise in the cost of living in the capital, by . p.c. in , . p.c. in and . p.c. in . the profit explosions triggered off thereby for lack of properly functioning trade unions fed the fires of the investment boom which had already enter- ed a critical phase. the excessive investments in - were chiefly concentrated in manu- facturing industry, the building trades, transport etudes economiques: portugal, published by oecd, paris, july , table f. : intereconomics, no. , portugal and communications. the investments in housing and agriculture stayed at their low level. in p.c. of all investments had gone into agriculture; in it was p.c. the contribution of agriculture to the national product fell from p.c. in to p.c. in , and agricultural production de- clined also in absolute terms, so that more food had to be imported. such a strong and lop-sided investment boom is bound to engender imbalances and disparities in the economy, and this will happen especially if the boom goes hand in hand with a general infla- tionary progression which abrogates the directive and indicatory functions of the price and makes virtually all investments look profitable. such a cyclical peak period comes usually to an end when the labour market has been exhausted and/ or political developments ensue which suddenly cause businessmen to believe that their profit expectations are too great. avoidance of a revaluation that the labour market which had already been put under a strain by the large number of emi- grants was relatively exhausted in is shown by the fact, that, especially in the second half of the year, the number of unfilled vacancies which had doubled in exceeded in some regions the number of applicants. such an "overemploy- ment" situation is highly unusual in a developing country with a mostly high number of unskilled workers. as early as december investment activity, which had still been rising sharply in the autumn, was receding fast. besides, the state- programmed investments underwent an overall decline in , which made the economy more slump-prone. in this context it is to be borne in mind that despite the manifest capital shortage one-third of the current expenditure under the budget (about dm . bn) was earmarked for unproductive military purposes. the fundamental mistake committed in the - period however was the accumulation of huge foreign currency reserves. an escudo revaluation was avoided. but imported goods (especially machinery and equipment) would have been cheaper if the exchange rate had been rais- ed, and increasing imports would have averted the expansion of the money circulation and thus the inflation and the cyclical overheating of the economy. larger imports, especially of agricul- tural machinery, are needed to make progress with the overdue modernization of agriculture and for the cultivation of the vast areas of unused land. the question remains why the bank of por- tugal accumulated gold and foreign currencies to the value of eventually (at the end of ) nearly dm bn, seeing that these kinds of assets yield scarcely any interest and agriculture in par- ticular was in urgent need of capital to finance tangible assets. energy crisis and recession in the industrial countries for the politician concerned with economic mat- ters it is always convenient if he can discover a foreign cause for an economic crisis. the attempt to establish a link between portugal's present problems and the energy crisis of / how- ever must prove abortive. the oil crisis caused the motor fuel price in portugal to go up from january , to february , by about p.c., but consumption in the first four months of was . p.c. higher than in the correspond- ing period of . the oil crisis accounted only for - percentage points of the rise of the gen- eral price index. official circles in portugal are making much of the supposition that the recession in the indus- trial countries spilled over to portugal, and at- tempts are being made to supply data to prove this. major items of the balance of payments are picked out and their changes interpreted. the embargo on guest workers, in germany for instance, was clearly due to cyclical unemploy- ment in the host country. such an embargo tends to reduce the foreign currency remittances of the emigrants. in actual fact however their transfers were as high in as they had been in . although a decline was noticed in the last quarter of and early , the transfers of escudos . bn in the first quarter of were still above the escudos . bn of the first quarter of . in real terms the remittances declined in to the extent to which prices rose in that year. but in the absence of other information it is almost im- possible to say whether the embargo on guest workers, unemployment among guest workers, reluctance to exchange foreign currencies into an escudo threatened by devaluation or political reasons were the cause. the political reasons alone can probably be ruled out because the transfers in the third quarter of reached their so far highest quarterly level (about dm bn), which suggests that the portuguese guest workers were welcoming and supporting the political changes in their homeland, but these figures can- not be taken as proof that the guest workers' re- mittances were a prime factor in originating the portuguese crisis. falling revenues from tourism the frequently expressed view that the subsidence of portugal's earnings from tourism was also due to the economic setback in the industrial states intereconomics, no. , portugal must likewise be rejected. they, like the guest wor- kers' remittances, remained constant, in money terms, during although they fell off in . since the situation in the tourist sector was gener- ally favourable, the explanation for the decline of the tourist trade as far as portugal is concerned is probably that the would-be tourists derived a dis- torted picture of the political situation in portugal from the mass media and kept away from portugal because they did not want to become involved in bloody demonstrations and arson. incidents of this kind were - insofar as they occurred at all - mostly confined to areas far removed from the tourist centres and largely staged by oppositional circles on the right. the shortfall in receipts from tourism has added to portugal's balance of pay- ments problems. changes in foreign trade the conjecture that responsibility for the origin of the crisis in portugal lies with the foreign trade is certainly plausible insofar as the principal buyers of portuguese exports - great britain, west germany and the usa which absorbed p.c. of portugal's exports in - are currently in an economic trough and may therefore be holding down their demand for portuguese products. if ex- ports decline, the national income and currency earnings will fall off and so will the import poten- tial and the investments. exports from portugal however increased in , both in volume and value, and the highest monthly figures were re- corded at the end of the year (in december they were equivalent to about dm bn). in the early part of the monthly exports fell back in value to the average (of about dm . bn equivalent). the relative stability of the exports may be due to their composition (textiles and foodstuffs account four about p.c.) which makes them resistant to cyclical changes. the balance of trade deficit however widened sub- stantially in -- a development which had already started in the second half of - not owing to rising prices but because of an enormous increase in the volume of imports the reason for which may have been that the escudo was not devalued as much as the inflation rates since required. another reason for the escalating import surplus in may have been the fear among importers that in order to defend its constantly dwindling foreign currency reserves the state would tighten the import restrictions which had been introduced in may but relaxed in july. it was thus not the recession in the industrial states but the inappropriate escudo rate (in relation to the dm it was devalued by p.c. only between the spring of and the spring of while prices in portugal went up by p.c.) which caused the balance of trade problems. the most frequently offered explanation for por- tugal's economic difficulties is that the crisis is the consequence of the revolutionary process, and this explanation is being supported by various statistics. the economic indicator of the geef (gabinete de estudos econ micos e financeiros) which in april still showed p.c. of "normal and above-normal" business activity fell in the next few months - in may to nearly p.c. and in june to over p.c. of "sub-normal" activity. the figures indicating "above-normal" activity had begun to decline as early as the autumn of . the situa- tion improved later in when the "normal and above-normal" activity rose to about p.c., but in the first half of it fell to about p.c. the number of protested bills doubled between april and may and quintupled in the following months. the decline in the number of protested bills from onwards had already come to an end by the middle of . the number of unfilled vacancies fell sharply in april and continued to decline throughout the year. this indicator was stabilized only in early and then at a low level. the number of redundancies has been re- ceding in but unemployment is rising fast (from , at the end of and , at the end of to , in the middle of ). this paradoxical trend is to be attributed to demo- bilizations from the army and the return of soldiers from the former colonies. besides, the opportuni- ties for emigration were greatly curtailed by the recession in the industrial countries. the number of new enterprises declined after the huge increase in , in the first quarter of slightly and in the second quarter substantially. in the third and fourth quarter it rose however so that the total was slightly above ( : , ; : , ). the industrial investments fol- lowed a similar course: they reached an annual low in may but in as a whole exceeded the figure by . p.c. in real terms. both these indicators had started to decline before the revolu- tion (the investments in december already), and this decline accelerated at first but soon made way for a recovery. this is in line with the move- ments of the geef economic indicator. in the overall trend was however downward. another indicator which points to the importance of april , for portugal's economic problems are the statistics of commercial bank deposits. after a vigorous expansion in - they have been slightly regressive since april . the lack of political security felt by the upper class is re- flected by the relatively large withdrawals from accounts with deposits above escudos mn (by intereconomics, no. , portugal . p.c. between the first and second quarter of ) while the deposits on accounts in the es- cudos , - , group rose by . p.c. there was also a shift towards longer-term and therefore higher-interest deposits. in the deposits de- clined also because the substantial wage increases resulted in some measure of redistribution between the firms which carry out money transactions with- out paying cash and the workers who for the most part have no cheque accounts yet. the decline of deposits, tardiness in effecting pay- ments and a strong demand for credit were bound to cause liquidity difficulties for the commercial banks. late in their surplus reserves were already unusually low because they had increased their lendings excessively. in april the reser- ves were generally below the minimum, and the banks retained their solvency only with emergency assistance by the central bank which boosted its rediscount credits between march and december (in april about p.c. of the banks' bills were rediscounted, in december p.c.) and lowered the minimum reserve ratios. one reason why this had to be done was that the officially stipulated rise of minimum wages - which the smaller firms in particular had great difficulty in financing - would otherwise have caused unemployment to rise further. but with production stagnating a cost inflation was the consequence. the monetary ex- pansion could not be maintained at the pace to which portugal had become accustomed in the preceding year as the political and economic un- certainties induced the public to rely much more on cash (the ratio of deposits to banknote circula- tion fell between and from p.c. to p.c.). even an increase in the banknotes in cir- culation by p.c. in proved insufficient. the rate of inflation stayed at p.c. however between may and may , which is due to the decline in the supply of goods and increased velocity of money circulation. the decline of the central bank's foreign currency reserves made it more difficult to expand the money circulation. the re- serves fell in by escudos . bn; escudos . bn were needed to balance the external pay- ments, and the remaining escudos . bn were probably lost through the flight of capital from the country which the central bank involuntarily fi- nanced through changes in its assets (rediscount credits in the place of foreign currencies). in the first half of the flight of capital was also due less to international interest differentials than to the uncertainty felt about portugal's future. the abrupt change of trend of several indicators in april/may must be regarded as evidence of the economic repercussions of the revolution of april even though the repercussions can- not be interpreted as altogether negative (e.g. in regard to investments). some of the programme items in the law of may , (no. / ) had certainly a positive effect on investment: [ ] liberalization of foreign trade and capital move- ments, [ ] encouragement of the return of emigrants, [ ] stimulation of private investment activity, [ ] support for small and medium-sized enter- prises, [ ] stressing of the importance of private initiative, [ ] equality of opportunities and abolition of pro- tectionism, [ ] restriction of public investments to the public sector, [ ] assistance for the regions, [ ] strengthening of the infrastructure. these measures are of especially great impor- tance for the viability of a market economy. on the other hand, there were some items which may have frightened away some investors because they affected firms' profits either directly or in- directly: [ ] fairer incomes distribution, [ ] counter-inflation measures, publications of the organisation for economic co-operation and development - oecd alternate months t h e o e c d o b s e r v e r the oecd observer is intended for people who are interested in and concerned with economic and social planning in the broadest sense and who want to have the relevant information in the most succinct possible form. special features for policy-makers and planners are in- cluded. subscription periods: january to december or july to june annual subscription price: dm ,- sales agent for the federal republic of germany: v e r l a g w e l t a r c h i v g m b h h a m b u r g intereconomics, no. , portugal [ ] steps against tax evasion, [ ] guaranteed minimum wages, [ ] workers' participation, [ ] protection for juvenile and female labour, [ ] social security, [ ] protection of the environment. these demands are recognized as justified in all industrial countries and in part being fulfilled by them. the term "nationalization" occurred in the mentioned law only in reference to the central bank and a commercial bank which performs simi- lar duties as the note-issuing bank - elsewhere the law only mentioned "intervention in vital eco- nomic spheres if required for the public weal". lack of support by the western industrial countries in a country which for several decades had been ruled by a fascist dictatorship the mentioned items of the programme may seem extremist and pos- sibly impair the propensity to invest of local and foreign enterprises, whose profits had never been endangered by trade union demands, but it was not to be expected that the western industrial states would also take alarm and put off giving the help which they had promised. but it must be pointed out that in the investments still in- creased although the changes which had occurred (bringing insecurity and wage rises) should have given added impetus to the cyclical turn-round already signified by the economic indicators in the winter ( / ). the events of april ap- pear even to have led to a certain stabilization of the economic situation, at least in the second half of . the lack of support on the part of the industrial countries of the western world was however bound to cause the provisional government to veer to the left. since march it has been nationalizing banks, insurance companies, electricity under- takings, the steel and shipbuilding industries, petro- chemicals, some big transport firms and the large estates. smaller and medium-sized firms were however expressly left in private ownership. as far as the nationalization of the big enterprises is con- cerned, it could be pointed out that they had had close links with the fascist dictatorship. neverthe- less the economic indicators showed an extremely negative reaction to the measures, and so a na- tional employment programme was adopted in april because of the large increase in un- employment. stress was laid on increased private according to a report in "wirtschaftswoche", it was still pos- sible for agfa-gsvaert before the putsch to pay portuguese women workers dm . an hour; later the firm had to pay at least dm . (wirtschaftswoche, no. , ). initiative but the need for public investments was also emphasized ( p.c. of the expenditure under the budget was earmarked for investments). a somewhat problematic system of automatic fi- nancing through money creation by the central bank was devised to ensure early discharge of public debts. provision was made for intervention in private enterprises in case their continuation as private firms was no longer assured. negative influence of foreign enterprises the problems to be tackled by means of this emergency programme, which was supplemented by a price stop, must unfortunately to a large part be attributed to the attitude of the foreign enter- prises which had invested large sums in portugal, especially since the late sixties. "extrapolating from the dynamic development of german indus- trial investments seen in portugal up to april , it can be assumed that investments of the order of about dm mn were deferred in alone, which corresponds to the loss of about , to , new jobs .,, as from in particular grun- dig, hoechst and siemens limited themselves in portugal to "replacement and supplemental invest- ments" . large-scale projects were in the mean- time put on ice, by hoechst for instance s. as this attitude also spread to trading, particularly in - "nothing is being bought from portugal because deliveries are too uncertain; nothing is being sold to portugal because the buyers cannot obtain foreign currencies" _ economic activity in portugal which had recovered slightly in was bound to fall off sharply in . it is to be hoped that the new government of azevedo which has been in office since septem- ber , will break out of this vicious circle which has aggravated the crisis, the more so as the costs in portugal - despite the additions from higher minimum wages, holiday pay, ban on dis- missals, plans for a hour week which the deg (german development company) bemoaned in the faz - are still very favourable for europe. a restoration of the conditions which prevailed before april cannot possibly be in the inter- est of the western democracies. official quarters should therefore at last give succour to portugal without imposing further political conditions . handelsblatt, dfisseldorf, april , . der spiegel, hamburg, april , . handelsblatt, d[isseldorf, april , . die zeit, hamburg, may , . frankfurter aiigemeine zeitung, frankfurt, july , . the following material was used additionally to the quoted sources: instituto nacionat de estat[stica: estatfsticas pare o planeamento - , lisbon ; indicadores econ mico-so- ciais, lisbon, third year, no. , april ; i inqu~rito de con- juntura ao comi~rcio, january-march . gabinete de estudos econ micos e financsiros, published by bsnco portug s do atl&ntico, conjuntura, january-february (no. ), conjuntura, may-june (no. ). intereconomics, no. , economic and monetary prospects: a spanish point of view * by fernando abril martorel ** the gradual rapprochement between spain and the european economic com- munity, and our now imminent integration in eec, will clearly demonstrate - and there can be no doubt on this score - the necessity of a series of reforms - in the insurance sector as elsewhere - capable of turning the insurance trade into an authentic instrument for providing safeguards in an unsafe world. indeed, if there is one distinctive feature marking today the economic future of our peoples, it is a high degree of insecurity. the question which should be put at the outset of any kind of discussion of our present circumstances, which are fairly common in the free world, is the following: what is politics doing for the economy of nations? our times are not easy ones for the making of forecasts with any degree of precision. the art of forecasting is made every day more difficult in a world which is full of uncertainties, which has been facing an almost universal economic crisis for six years now and which has to deal with such serious problems as the energy crisis, calling for thorough going reforms and adjustments. the international monetary disarray, which the floating exchange rates appear to have accentuated, the great increase in public spending in the last few years, the problems existing with regard to certain basic industries, the ever-increasing unemployment, inflation and slow growth, are some other of the features of this complex era in which we are living. nevertheless, it is not possible to renounce to some measure of programming, to the responsibility for regulating economic activities, however liberal one's point of departure may be. the monetary aspects, both internal and international, such as those relating to public spending and public revenue, constitute eloquent examples in this respect. it is difficult nowadays for one country alone to give up all controls over the movement of the monetary mass or to introduce any more or less open intervention in the international quotation of its currency. in spain, monetary policy focuses its attention on the growth of the quantity of currency in circulation in the broad sense - in its m form - and on regulating its growth through the controls imposed on liquid assets. all this is done because of the feeling that it is that particular variable which best reflects the evolution of total demand, and the one which can be controlled most efficiently. moreover, like in other countries, the monetary policy of spain is assigned tasks which are not funda- mental but are nevertheless relevant to the overall strategy of economic policy. * presented in madrid to the general assembly of the "geneva association" on th july . ** vice-president of the spanish government. thus, in , in pursuance of the economic adjustment programme applied by our government, and with the consent of the other parliamentary political forces, an agreement which was embodied in the so-called "pactos de la moncloa ", the monetary policy has contributed to the significant reduction of the rate of inflation and has played a fundamental role hi the considerable slowing down of the rise in prices - from . per cent in to . per cent in , measured as per the index of consumer prices from december to december - registered in the past financial year by our economy. as has occurred in certain other countries - germany and switzerland being clear examples in this respect - the efforts to control the growth of the money supply had to contend both with the obstacles arising from the great increase in reserves as a result of the restrictive monetary policy, of the liberalization of the financial system and of the abundance of international liquidities. it is sufficient to point out in this connexion that in the last two years, from july until the present time, the foreign currency reserves of spain have risen from a little more than $us , million to over $us , million the balance of trade surplus both in current account and in capital account, and the corresponding rise in reserves and consequent injection of liquidity into the system, have been basically the origin of the problems of monetary control which we have experienced in the past financial year and which, in one way or another, continue in the present year. the weakness of the dollar has obviously influenced this situation, despite the effectiveness which the measures taken on st november of the past year may have had. in situations such as the one described above it seems quite obvious that foreign exchange flexibility constitutes a line of defence of the autonomy of the internal monetary policy. in the past fourteen months, the peseta has risen considerably against all other currencies, but this has not been sufficient to slow down in any significant manner the expansion of the foreign sector, owing to the fact that the chief items of our balance of payments are not sufficiently sensitive to short-term fluctuations of the foreign exchange rate, and to the fact that the spanish economy still has a high level of protectionism in certain sectors and of general interventionism in the foreign exchange market. another source of problems for the monetary policy is the public sector, its deficit and its financing. in this sense, the limitation of public spending - which is sought nowadays by so many european countries - and the financing through a diversified public debt at market prices, constitute absolutely essential steps to take. at this very moment, we are considering the goals for a monetary policy for the second part of this present year. no attempt will of course be made to solve the problems of the real economy with measures of a monetary kind. but there can be no doubt that recent events in the realm of oil prices suggest that prudence is called for in the financing of its inflationary effects, without losing sight of the long-term and medium-term objectives which must continue to govern the strategy of this policy, in the contribution which it will make to the task of curbing the rising trend of prices. in any case, monetary policy is part and parcel of economic policy and it must faithfully serve its overall objectives. the prospects of the spanish economy, like those of any other country at our same level and stage of development, have been gravely affected by the steep rise in oil prices agreed on in geneva at the end of the month of june last. for this year, we had programmed for a growth of the order of to per cent and an inflation rate of . to per cent. today it can be safely asserted that the growth objective is going to be / . per cent below the original estimate and that the inflation rate will rise by two points. similar changes of objectives - and in the same direction - are becoming normal in all the countries which are highly dependent on imported energy. the oecd and imf have just revised downwards their estimates for growth and their forecasts regarding the rise of inflation rates. it is obvious that the prospects of the spanish economy - for this year and in the medium-term - are very much conditioned, not only by the success of the policy of economic adjustment and reform undertaken two years ago, but also by the rate of growth of the industrialized countries and by the economic policies which they follow in the present juncture. at present, it seems less likely that the rate of economic growth of the countries members of oecd can be higher than / . per cent as an average during the next five years, a rate which can moreover be adversely affected by the consequences of the energy crisis, both as regards its price effects and as regards shortage of supplies. the economic prospects of spain will be necessarily influenced by the greater or lesser success which we will achieve in the field of the struggle to control inflation. during the past few years, the rates of increase of prices in spain have been consid- erably higher than the average for all the countries members of oecd, although this difference has decreased substantially during the past year and a half. this objective of closing the gap between our prices and those of the countries with which we have most of our trade relations cannot be abandoned in any way. and to persist in the pursuit of this objective would require the adoption of policies for the strict control of demand. in addition, the attitude adopted by the taxation authorities is of special impor- tance in avoiding adverse effects upon price movements by means of policies calculated to compensate for losses in real income caused by the rise in energy prices. these price rises imply, as has so often been said, a deterioration in our balance of payments position and a fall in our production and it would serve no useful purpose to try to make up for these losses merely by raising money incomes. the linking of money salaries to the level of prices of a recent past has the effect of merely perpetuating inflation without ensuring the maintenance, and still less the growth, of real salaries. at the present moment, there is also great concern at the developments in the public sector, which has experienced a considerable increase in its deficit in recent months and which is now creating problems for the monetary policy of the country and for the private sector with regard to the share of financing corresponding to that sector. the government is making considerable efforts in order to curb the growth of public spending and to increase its efficiency. it is more than likely that the high rates of economic growth which have been recorded until now have been due to exceptional circumstances - namely cheap energy, a comparatively simple technological development and especially favourable political and economic conditions. in the future, we can expect rates of growth to be lower and the productive process - which will be more weekly fed and of an increas- ing complexity - to demand, through the agency of international solidarity, the necessary security to afford maximum stimulation to the factors of development. it is a generally recognized phenomenon that economic growth and, above all, economic development, with its connotations which are not only quantitative but also qualitative in scope, shows an increasing complexity, a greater interdependence between the production factors and, in the relations between the various national economies, a higher rate of capitalization and, in the last instance, a greater measure of vulnerability. growth, which is more than proportional as regards the gnp of insurance in the western world, provides a first indication of the existence of the above-mentioned phenomenon, which results in an increasing necessity to achieve new standards of security. from a sociological standpoint, it is clear that in a free and democratic society and system like those of spain and the other western european countries, security tends to be achieved without detriment to freedom. this is possibly a favourable moment for asking ourselves whether the institutions involved in the creation of this type of security are in a position to respond satisfactorily to the demands of more complex - and possibly less powerful - economies, and to the growing needs of security on the part of individuals, firms and the community as a whole. i have the impression that for many years the insurance world in general, and the spanish insurance world in particular, has lived in a sort of comfortable ivory tower, self-sufficient in its complex legal and actuarial techniques and somewhat far away from the problems which large part of society and of the other economic sectors have had to face. at present, i believe that special importance must be attached to the study of insurance economics. its adaptation to existing needs is illustrated by the objective which it has adopted of placing insurance problems in the context of the modern economy and modern society; and also in the objective of seeking to bring about the emergence, above possible antagonisms between economic factors, of the interest which they all have in facing together the problem of risk in a rapidly developing world, in which persons feel a growing desire for security in freedom. in this sense, it is satisfactory to note the success of the geneva association. personally i am convinced that the spanish insurers are aware that they must accept profound changes in order to adapt themselves to the needs of security which emerge from the uncertainties arising from a crisis with the characteristics of the one that the whole of the western world has been experiencing for the past six years. insurance must be an instrument for providing guarantees of personal freedom, as well as an important stimulating factor for economic activity, especially through its function in the channelling of savings and in long-term investments. these two contributions of security and personal freedom on the one hand, and of an element of non-inflationary financing for economic development on the other, represent the two great challenges which the spanish insurers have to face. these, of course, are not the only aspects which condition the economic prospects of spain. but these thoughts have purported to point briefly to some of the subjects which concern today those of us who have responsibilities in the shaping of economic policy. times are difficult, but it is precisely in these moments that the capacity of a country to move ahead is tested. spain has given proof of great potentialities in finding solutions for its political problems, in the transition from an authoritarian regime to a democracy. i am sure that in the face of the present economic crisis as well, a crisis which is at present affecting the whole world, we will be able to overcome these difficulties, and show once more satisfactory growth rates which will ensure the creation of a sufficient number of new jobs and the raising of the levels of well-being attained by the population. 	economic and monetary prospects: a spanish point of view * november . volume , number american association for the advancement of science science serves its readers as a forum for the presentation and discussion of important issues related to the advancement of science, including the presentation of minority or conflicting points of view, rather than by publishing only material on which a consensus has been reached. accord- ingly, all articles published in science-including editorials, news and comment, and book reviews- are signed and reflect the individual views of the authors and not official points of view adopted by the aaas or the institutions with which the authors are affiliated. editorial board ' alfred brown james f. crow seymour s. kety frank press hrberr s. gutowsky n. bruce hannay donald kennedy danifl e. koshland, jr. frank w. putnam maxine f. singer gordon wolman f donald lindsley ruth patrick raymond h. thompson editorial staff editor: philip h. abelson buisiness manager: hans nussbaum managing editor: robert v. ormes assistant editors: ellen e. murphy, john e. ringle assistant to the editors: patricia rowe news and comtnent: john walsh, luther j. carter, deborah shapley, robert gillette, nicho- las wade, constance holden, barbara j. cullrron, scherraine mack research news: allen l. hammond, william d. metz, ihomas h. maugh ii, jean l. marx, arthur l. robinson, gina bari kolata, fannie groom book reviews: katherine livingston, lynn manfield, janet kegg cover editor: grayce finoer editorial assistants: margaret allen, isabella bouldin, eleanore burrz, mary dorfman, sylvia eberhart, judith givelber, corrine harris, nancy hartnagel, oliver heatwole, chrstine karlik, margaret lloyd, eric poggenpohl, jean rociwood, leah ryan, lois schmrr. richaild semixlosz, ya li swigart, eleanor warner guide to scientific instruments: richard sommnr membership recruitment: gwendolyn huddle; subscription records and member records: ann ragland advertising staff director earl j. scherago production manager margaret sterling advertising sales manager: richard l. charles sales: new york, n.y. : herbert l. burklund, w. st. ( -pe- - ); scotch plains, n.j. : c. richard callis, unami lane ( - - ), chicago, ill. : jack ryan, room , n. michigan ave. ( -de - ); bev- erly hills, calif. : winn nance, n. la cienega blvd. ( - - ); dorset, vt. : fred w. dieffenbach, kent hill rd. ( - - ) editorial correspondence: massa- chusetts ave., nw, washington, d.c. . phones: (area code ) central office: ; book re- views: - ; business office: - ; circula- tion: - ; guide to scientific instruments: - ; news and comment: - ; reprints and permissions: - ; research news: - ; reviewing: - . cable: advancesci. washington. copies of "instructions for contributors" can be obtained from the editorial office. see also page xv. science, june . advertising corre- spondence: room , w. st., new york, n.y. . phone: -pe- - . scie:ncet on incrementing a hurricane scientific studies of national decision-making have shown that democ- racies tend to abhor comprehensive planning and major shifts in strategy, preferring instead to "increment" or muddle through, making adjust- ments through a series of small steps aimed at moving away from a mess rather than at moving toward clearly stated, positive goals. thus, a study of our country's federal budget shows that the allotment for most federal agencies will usually be within percent of last year's- come hell or high water. national priorities may change, new crises may be identified; but as a rule agencies entrusted with new missions will grow only slowly, while the custodians of obsolescent missions and downgraded priorities are likely to continue to draw "their" billions. it has been argued that it is the genius of democratic policy-making that it takes into account the large variety of needs and interests repre- sented in the populace, and does not lend itself to a sudden shift to one side to the neglect of others. thus, it is "undemocratic" to suggest cutting the nasa budget by a factor of while quadrupling that of the office of energy. this would be "unfair" and unsettling to the industries that grew up around the space effort and to the congressional districts in which they are located. gradual transitions, which do occur, allow for less painful adjustments. finally, master plans often do not work anyhow, the future is too complex to be anticipated and molded, today's grand designs are tomorrow's discarded charts. muddling through, the incrementalists conclude, is not just a fact of life, but the best way to live. while much of what the incrementalists say is valid, there are moments when muddling through just will not do to get a country out of a serious predicament. france discovered this when it was invaded in . the united states realized it had to double the defense budget, within one year, in terms of percentage of the gross national product, at the onset of the korean war. the energy crisis has so far elicited chiefly rather modest attempts at muddling. a year after the crisis broke we still have no national policy, let alone a program commensurate with the problem. the ideas being kicked around, which are a long way from attaining even the status of policies, are quite incremental in nature. project independence, aimed at making us self-reliant in years, is little more than a slogan. major decisions about the sources of energy to focus on, how to develop them, even whether independence is worth the gigantic costs it would exact, have in effect not been made. most importantly, the american people have not yet been prepared for the fact that whichever way we turn-toward consuming a good deal less energy or paying much more for its development-the american way of life will have to be significantly adjusted over the next decade. estimates of how much project independence will cost run to $ billion. while incrementing might well be the genius of democracy under most circumstances, to try to muddle through a hurricane is folly. the nation must be told that this crisis is not temporary and that it will require a not trivial reduction in the american standard of living, albeit not a radical one. it will require more master planning and national coordination than we tend to welcome in peacetime. it will require more leadership and less incrementation.-amitai etzioni, professor of sociology, columbia university, and director, center for policy re- search, inc., riverside drive, new york for sttidies on incr-ementing, see richard fenno, the power of tlte puirse (little, bi-own, ' oston, ) and aaron wildawsky and arthur hammond, "comprehensive vs. incre- mental budgeting in the department of agriculture," administrative scieni e quearter!l', vol. ( ). for an analysis of the demilocratic basis, see charles lindblom, the ltitelli- gence of democracy (free press, new york, ). for critiqtue, see amiiitai ftzioni. i/lie a cive societr (free press. new york, f), chapters aind . o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/ on incrementing a hurricane amitai etzioni doi: . /science. . . ( ), . science article tools http://science.sciencemag.org/content/ / / .citation permissions http://www.sciencemag.org/help/reprints-and-permissions terms of serviceuse of this article is subject to the is a registered trademark of aaas.scienceof science, new york avenue nw, washington, dc . the title (print issn - ; online issn - ) is published by the american association for the advancementscience by the american association for the advancement of science o n a p ril , h ttp ://scie n ce .scie n ce m a g .o rg / d o w n lo a d e d fro m http://science.sciencemag.org/content/ / / .citation http://www.sciencemag.org/help/reprints-and-permissions http://www.sciencemag.org/about/terms-service http://science.sciencemag.org/ d/ d heterojunction of r-scheme ti c mxene/mos nanosheets for enhanced photocatalytic performance nano express open access d/ d heterojunction of r-scheme ti c mxene/mos nanosheets for enhanced photocatalytic performance ziyu yao , , , huajun sun , , , huiting sui , , and xiaofang liu * abstract combination of two-dimensional ( d) materials and semiconductors is considered to be an effective way for fabricating photocatalysts for solving the environmental pollution and energy crisis. in this work, novel d/ d heterojunction of r-scheme ti c mxene/mos nanosheets is successfully synthesized by hydrothermal reaction. the photocatalytic activity of the ti c mxene/mos composites is evaluated by photocatalytic degradation and hydrogen evolution reaction. especially, . wt% ti c mxene/mos sample exhibits optimum methyl orange (mo) degradation and h evolution rate of . % and h evolution rate of . μmol h − g− , respectively, which is attributed to the enhanced optical absorption ability and increased specific surface area. additionally, ti c mxene coupled with mos nanosheets is favorable for improving the photocurrent response and reducing the electrochemical impedance, leading to the enhanced electron transfer of excited semiconductor and inhibition of charge recombination. this work demonstrates that ti c mxene could be a promising carrier to construct d/ d heterojunction in photocatalytic degradation and hydrogen evolution reaction. keywords: d/ d heterojunction, hydrothermal reaction, photocatalytic degradation, h evolution reaction introduction over the past few years, the industrial science and technology is developing significantly, whereas the en- vironmental problems and energy crisis have become much more serious [ – ]. significant application of ti- tanium oxide (tio ) for splitting water has been re- ported since [ ]. researchers have been working to extend the response of the tio -based composites to visible light region and explore the narrow bandgaps semiconductor to deal with environmental pollution and energy crisis better [ – ]. metal sulfide semiconductor catalysts have been con- sidered as essential carriers to solve environmental pol- lution and energy crisis due to the narrow bandgaps, low toxicity and excellent catalytic ability [ , ]. the relatively narrow bandgap (eg = . ev), unique optical properties and layered structure of mos nanosheets have attracted more and more attention [ – ]. mos has been coupled with several two-dimensional ( d) ma- terials and semiconductors, such as tio [ ], graphene oxide (go) [ ], g-c n [ ], sno [ ], bi wo [ ], bi o co [ ], and cds [ ], in order to improve the efficiency of photocatalytic degradation and hydrogen production. it has been proved that higher concentration of methyl orange (mo) ( mg/l) organic pollutants can be degraded in min under the visible light irradiation by mos /cds nanocomposites [ ]. since the initial report in , mxenes, as a member of the two-dimensional material family, has attracted ex- tensive attention of researchers [ – ]. mxenes can be prepared from max phase by etching the a-layer with hf or hcl/lif, which possesses excellent electrochem- ical properties, chemical stability, and numerous hydro- philic functionalities on the surface (-oh/-o) [ – ]. © the author(s). open access this article is licensed under a creative commons attribution . international license, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the creative commons licence, and indicate if changes were made. the images or other third party material in this article are included in the article's creative commons licence, unless indicated otherwise in a credit line to the material. if material is not included in the article's creative commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. to view a copy of this licence, visit http://creativecommons.org/licenses/by/ . /. * correspondence: @qq.com school of chemistry, chemical engineering and life sciences, wuhan university of technology, wuhan , people’s republic of china full list of author information is available at the end of the article yao et al. nanoscale research letters ( ) : https://doi.org/ . /s - - -z http://crossmark.crossref.org/dialog/?doi= . /s - - -z&domain=pdf http://creativecommons.org/licenses/by/ . / mailto: @qq.com the most popular ti c mxene can be obtained by exfoliating ti alc with strong acid [ ]. its out- standing conductivity and two-dimensional layered structure have been considered as energy storage ma- terials for sodium-ion batteries (sibs) and electro- chemical capacitors [ – ]. ti c mxene with rich oxidized surface groups favors the heterojunction formed between mxene and semi- conductors [ – ]. the heterojunction assists to estab- lish strong interface contact between photocatalyst and cocatalyst. due to the strong physical and electronic coupling effect, the interface contact can greatly enhance the transfer and separation of photo-induced carriers on the heterojunction interface, which is the key factor to improve the photocatalytic performance [ – ]. for example, tio /ti c and ti c /bi wo compos- ites have exhibited excellent photocatalytic co reduc- tion activity, which is ascribed to the highly efficient charge-carrier separation and rich activation sites [ , ]. the hydrogen production performance of the g- c n /ti c photocatalyst has enhanced significantly, which is attributed to the superior electrical conductivity and highly efficient charge transfer [ ]. tio /ti c and α-fe o /ti c hybrids are proved to promote the photocatalytic degradation efficiency of organic pollut- ants under ultraviolet light and visible light by construct- ing heterojunctions [ – ]. herein, d/ d heterojunction of r-scheme ti c mxene/mos photocatalysts is synthesized by hydro- thermal method. photocatalytic activities of ti c mxene/mos composites are evaluated by photocata- lytic degradation of mo and hydrogen evolution reac- tion (her) under visible light irradiation. photocatalytic performance reflects that mos coupled with ti c mxene presents higher degradation ability and h pro- duction rate than pure mos under the same condition. the enlarged specific surface area and enhanced optical absorption ability can be attributed to the morphology of mos nanosheets change from crouching to stretch- ing, which is induced by ti c mxene. above all, the strong interaction between mos and ti c mxene is beneficial to construct d/ d heterojunction, which ef- fectively promotes the separation and transfer of photo- electrons from vacancies, thus enhancing the photocatalytic activity significantly. method/experimental section photocatalysts preparation raw materials ti alc max powders (> wt% purity), hydrofluoric acid, ammonium molybdate ((nh ) mo o • h o), thiourea ((nh ) cs) and methylene orange are pur- chased by shanghai yuehuan co., ltd. (shanghai, china) and guoyao chemical co., ltd. (china), respectively. synthesis of ti c nanosheets ti alc black powder is etched in % hf solutions at room temperature via stirring for h to remove the al layer. the disposed powder is washed by deionized water via centrifugation ~ times until the ph reaches . the suspension of ti c is sonicated for h and then centri- fuged for min at , rpm [ ]. finally, the solution is dried to obtain the final product ti c mxene nanosheets. hydrothermal preparation of ti c mxene/mos (denoted as tm) composites firstly, . g of ammonium molybdate ((nh ) mo o • h o) and . g of thiourea ((nh ) cs) are dissolved in deionized water under vigorous stirring for min to form a homogeneous solution, which is la- beled as solution a. then, an amount of ti c nano- sheets is added to ml deionized (di) water stirring for min followed by additional ultrasonication for min, which is labeled as solution b. then b is mixed into a drop by drop under ultrasonication for min. the mixed solution is transferred into a ml teflon-lined autoclave and held at °c for h. after cooling to room temperature, the obtained black catalysts are washed by di water for three times to remove dispersing agent, and then dried at °c for h in a vacuum oven. by adding the ti c solution, the mass ratio of ti c mxene to mos is set as , . %, . %, . %, . %, and . wt%, respectively. the prepared samples are labeled as tm , tm . , tm . , tm . , tm , and tm , respectively. photocatalytic degradation of methylene orange all the degradation experiments are carried out in a ml beaker with a constant stirring. methyl orange is se- lected to evaluate the photocatalytic activity of the sam- ples. the photocatalytic degradation test of mo is performed by using a w metal halide lamp. in a typ- ical experiment of mo degradation, mg of ti c / mos sample is dispersed into ml mo aqueous solu- tion ( / / mg/l). then, the solution with catalysts is placed in the dark for min under strong magnetic stirring to establish adsorption equilibrium. the samples are processed by ultrasonic for min before turn on the light, which makes the catalyst dispersed well in the so- lution. at certain time intervals, approximately . ml of mixed solution is extracted with centrifugation treat- ment for min at rpm− to remove the solid cata- lyst powder. the change at nm wavelength is determined by the concentration of the mo solution, which is measured by using an uv-visible spectropho- tometer. the initial concentration of the mo solution is labelled as c , and ct refers to the concentration of mo solution at a certain time, respectively. the degradation yao et al. nanoscale research letters ( ) : page of efficiency of the sample is reflected by the relative ab- sorbance ct/c . photocatalytic hydrogen production evaluation the photocatalytic h evolution tests are carried out in a ml quartz flask under ambient temperature and at- mospheric pressure. five milligram of tm sample is dis- persed in ml aqueous solution containing . m na s and . m na so , and irradiated by w xe lamp equipped with a nm cutoff filter. before irradi- ation, gas (n ) is continuously passed through for min to remove the oxygen. the production of h is de- tected by gas chromatography (agilent ) equipped with tcd detector. microstructure characterization the phase analysis of the ti c /mos samples is oper- ated at kv and ma by x-ray diffractometer (xrd, cu kα, bruker d advance, germany). the micro- morphology of the composites is observed by field emis- sion scanning electron microscopy (fesem, zeiss ultra plus, zeiss, germany) coupled with energy-dispersive spectrometry (eds). high resolution transmission elec- tron microscopy (hrtem, jem- f, japanese elec- tronics, china) is used to observe the morphology and heterojunction interface between mos and ti c . the infrared spectra are recorded by fourier transform infra- red spectroscopy (ftir, nexus, therno nicolet, usa) in a range of to cm− . the optical properties of powders are performed by uv-vis diffuse reflectance spectroscope (drs, lambda s, perkinelmer, usa) with an integrated sphere. chemical states of the ob- tained catalysts are studied by x-ray photoelectron spec- troscopy (xps, escalab xi, thermo fisher scientific, china). electrochemical measurements the electrochemical tests are measured by a chi electrochemical station. in a typical experiment, mg of tm sample and μl of wt% nafion solution are dis- persed in . ml of : v/v ethanol and water with min sonication to form homogeneous suspension. subse- quently, μl of the ink is dropped onto the glassy car- bon electrode (gce) surface. the electrochemical impedance spectroscopy (eis) tests are carried out in the same configuration at overpotential n = mv from . to khz with an ac voltage of mv. results and discussion crystalline of ti alc and ti c mxene is analyzed in the range of θ = − °, as shown in fig. s . the re- markable diffraction peak of ti alc located at θ = ° disappears and peak of ti c mxene θ = . ° shifts to lower angles, suggesting that ti alc has transformed to ti c successfully [ ]. figure reveals xrd patterns of tm samples with various ti c additions and the main diffraction peaks of tm sample have been indexed to pure mos with lattice constants a = . and c = . Å (jcpds no. - ), respectively [ ]. after coupled with ti c , the main diffraction peaks for ( ), ( ), and ( ) planes of tm composites display broader and decreased intensity than tm , suggesting that mos is suppressed by ti c growth limiting effect [ ]. no obvious diffraction peak of ti c mxene can be detected, which is attributed to the low ti c loading with well dispersion in the composites. morphological images of ti c /mos composite with various ti c amounts are observed in fig. . it shows that all of the samples reveal flower-like nanosphere fea- ture with holes separated randomly in the surface. and the flower-like structure of tm composites is composed from irregular nanosheets with average thickness of about nm. figure a exhibits typical microscopic structure of tm with diameter of about - nm. figure b-f gives fesem images of tm . , tm . , tm . , tm , and tm . it can be seen that all the samples share simi- lar morphology feather with pure mos . layered ti c mxene has smoother surface and the flower-like mos microsphere enrichment at the edge of the lamellae, in- dicating that the structure of ti c mxene is not destroyed during hydrothermal synthesis. figure s a re- veals the d/ d heterojunction with intimate coupling between ( d) mos and ( d) ti c . the corresponding eds mapping images are obtained in fig. s b-e, which reflects that mo, ti, and c elements dispersed uniformly in the tm composite. the optical absorption property of tm composites is analyzed by uv-vis drs spectrum, as revealed in fig. a. fig. xrd patterns of tm , tm . , tm . , tm . , tm , and tm composites yao et al. nanoscale research letters ( ) : page of tm . possesses the strongest optical absorption ability in the range of visible and uv light in sharp contrast with tm . one can note that in a certain range, the optical ab- sorption intensity of tm composites is enhanced signifi- cantly with the increase of ti c content. especially, excessive ti c reduces the photocatalytic performance of the tm samples, which is ascribed to the fact that exces- sive ti c addition prevents the light absorption of mos nanosheets [ ]. figure b shows the n adsorption-desorption iso- therms of tm and tm . samples and their pore size distribution curves (fig. b inset). both of the samples are treated at °c for h before testing. the average pore size of tm and tm . is . and . nm. the brunauer-emmett-teller surface area of tm and tm . samples is . and . m g− , respectively, sug- gesting that tm . has a larger specific surface area and greater n adsorption capability than tm sample. the separation efficiency of photo-generated holes and electrons is confirmed by the transient photocurrent re- sponse (i-t curves), as shown in fig. c. tm . sample exhibits higher photocurrent intensity than tm , which is ascribed to the effective migration of photoelectrons from the conduction band of mos to ti c nanosheets. the charge carrier recombination/transfer behavior of tm samples is explored by electrochemical impedance spectra (eis), as presented in fig. d. among those sam- ples, the biggest and the smallest arc size of nynquist curve are displayed by tm and tm . photocatalysts, respectively, indicating the high conductivity of ti c mxene is beneficial to the electron migrate. however, a bigger radius of the arc can be observed in tm sample (fig. s ), which suggests that too high ti c loading leads to the increase of carrier transfer impedance. obvi- ously, the well agreement of i-t and eis results confirms that the content of ti c can affect the transfer of photogenerated carriers. figure s shows the ft-ir spectrum of tm and tm . samples. the absorption bands at , , , and cm− are correspondence to the mo-s, s-s, mo-o, and -oh stretching, respectively [ ]. the band at about cm− is attached to -ch group from sur- face water stretching vibration [ ]. compared with tm sample, all the peaks of tm . samples exhibit a slight shift, suggesting strong interaction is emerged be- tween mos and ti c nanosheets. hrtem images of tm and tm . composites are further observed in fig. a, b. overall, the degree of overlap for mos nanosheets and agglomeration for mos microsphere decreases with ti c addition in- creasing. in detail, for the pure mos nanosheets, the overlap for the mos can be noticed, which is not bene- ficial for the absorption of visible light, as shown in fig. a. with the increase of ti c addition, the morphology of mos gradually changes from crouching to stretching state (fig. b), which could bring out the enlarged spe- cific surface area and increased active sites. the ultrathin layered ti c nanosheets are well dispersed in solution and closely contact with mos . this is favorable for fa- cilitating mos nanosheets stretch through strong fig. fesem images of a tm , b tm . , c tm . , d tm . , e tm , and f tm yao et al. nanoscale research letters ( ) : page of physical coupling, which will play an important role in electron transfer in photocatalytic process. while, as ti c content further increases to and wt%, a large number of mos nanosheets randomly overlap- ping and agglomerating on ti c substrates, as shown in fig. s a, b. figure c gives the heterojunction structure of tm . . the lattice spacing of . and . nm is assigned to ( ) crystal plane of ti c and ( ) crystal plane of mos , respectively [ , ]. the intimate-contact hetero- junction promotes the transfer and separation of photo- generated carriers and holes at the heterojunction interface [ ]. more details of heterojunction structure in tm samples can be observed in fig. s c, d. the scan- ning transmission electron microscopy (stem) of tm . is displayed in fig. d, and the corresponding eds mapping of mo, s, c, ti, and f is given in fig. e-i. the atomic ratios (fig. s ) of c, ti, mo, and s elements are . , . , . , and . %, respectively. the clear outline of flower-like mos grafted on ultra-thin ti c nanosheets proves that ti c nanosheets coupled with mos construct intimate heterojunction successfully. all the evidences of sem and tem images indicate that the tm composites are synthesized successfully. for further confirming the coexistence of ti c and mos in the composite, xps is taken for analyzing the surface chemical composition and states of tm . sam- ple, as shown in fig. . all elements (mo, s, ti, o, c) are observed in the xps survey spectra. characteristic peaks . , . , . , . , and . ev are indexed as ti p, s p, mo d, c s, and o s, respectively [ ]. in fig. b, three peaks at the binding energies of . , . , and . ev are assigned to s s, mo d / , and mo d / , respectively, revealing the existence of mo + in tm hybrids. as shown in fig. c, two peaks are situated at . and . ev, in accordance with s fig. a uv-vis diffuse reflectance spectra (drs) of as-synthesized tm , tm . , tm . , tm . , tm , and tm samples. b n adsorption-desorption isotherms for the as-prepared tm and tm . powders. c photocurrent response of tm , tm . , tm . , tm . , tm , and tm . d electrochemical impedance spectra of tm and tm . sample yao et al. nanoscale research letters ( ) : page of p. the peaks of c s belong to ti c is appeared at the binding energies of . and . ev, as dis- played in fig. d. figure a, b exhibits the photocatalytic activity for the degradation of mo over various tm samples under vis- ible light irradiation. the blank experiment proves that there is no obvious change in the mo solution within min reaction in the absence of catalyst, as given in fig. a. it turns out that mo molecules are proved to be chemically stable and difficult to be decomposed. the adsorption effect is eliminated before photocatalytic deg- radation by stirring the mixtures in the dark for h. after being treated in the dark for min, ~ % of mo is adsorbed by different tm composites. all of the samples demonstrate strong physical adsorption abilities and the tm . sample shows great adsorption ability than others due to the increased specific surface area. after adsorption, subsequent photocatalytic degradation experiments are carried out with equilibrium mo con- centration as initial concentration. obviously, all the tm composites display higher photodegradation abilities than pristine mos under vis- ible light irradiation, suggesting that a small amount of ti c mxene addition can enhance the photocatalytic activity of mos . when the increase of mxene addition from to . wt%, the total degradation of mo increases dramatically. the highest photocatalytic performance is obtained by tm . sample and . % mo solution is fig. a, b tem images of tm and tm . samples. c hrtem image of ti c /mos . d a stem image. e, f, d, h, i eds mapping images of mo, s, c, ti, and f elements of tm . sample yao et al. nanoscale research letters ( ) : page of degraded within min. by further increasing the ti c addition to wt%, the degradation ability of tm com- posites catalysts is decreased. this phenomenon can be attributed to the fact that too much ti c hinders the absorption of visible light by mos nanosheets, reducing photocatalytic activity [ ]. the comparison of different tio -based composites for photocatalytic degradation of mo under visible light irradiation is shown in table s . moreover, the degradation kinetics of mo have been fitted as plotted according to pseudo-first-order kinetics theory (ln (c /ct)) = kt, where k is the apparent first- order rate constant, as shown in fig. b. it can be ob- tained that the kinetics rates constant for tm , tm . , tm . , tm . , tm , and tm are . , . , . , . , . , and . min− , respect- ively. the optimal value of k belongs to tm . sample, which is about . times higher than the tm . in order to investigate the photocatalytic activity of tm . composites under various mo concentrations, the degradation for , , and mg/l of mo solu- tion is given in fig. s a. in general, the degradation efficiency of tm . sample decreases as the concen- tration of mo solution increases. as can be noticed, > % of lower concentration mo solution is de- graded within min. figure s b, c shows the changes of ultraviolet absorption spectra of and mg/l mo solution, respectively. the strong ab- sorption peak of mo solution at nm decreases gradually due to the photodegradation effect of tm . . moreover, tm . sample also exhibits strong degradation ability (nearly %) for the degradation of mo ( mg/l) in min. above results prove that tm photocatalysts have potential prospects for the degradation of high concentration organic pollutants. fig. a xps survey spectra and high resolution xps spectra of b mo d, c s p, d c s in tm sample yao et al. nanoscale research letters ( ) : page of the stability of photocatalyst is tested by repeating three times under the same condition. separation of tm . from mixture solution by high-speed centrifugal treatment. the stability of tm samples is revealed in fig. a, the photocatalytic activity of the tm . sample does not decline significantly after recycles of the photodegradation process, which demonstrates that the photocatalyst possesses superior stability and sustainabil- ity [ ]. the structural stability of photocatalysts is ob- tained by comparing the xrd before and after use, as shown in fig. s . the potential mechanism of photocatalytic degrad- ation is obtained by trapping experiments. the photogenerated holes (h+) and hydroxyl radicals (•oh) play crucial roles in photocatalytic degradation process [ ]. triethanolamine (edta) and t-butanol are intro- duced as the scavengers to quench active holes (h+) and hydroxyl radicals (•oh) under visible light irradiation, respectively. as displayed in fig. b, the tm . compos- ite exhibits the best photocatalytic activity when no scav- enger is added. in the presence of edta or t-butanol, the degradation of mo is remarkably inhibited, suggest- ing that the photogenerated holes and hydroxyl radicals all take part in the photocatalytic reaction. after adding edta, the degradation of mo decreases significantly (less than %), indicating that holes play a key role in fig. a recycling photocatalytic experiments of tm . sample for photocatalytic degradation of mo by repeating three times under same condition. b effects of different scavengers on the mo photodegradation process under visible light fig. a photocatalytic degradation performance. b the corresponding rate constant k values of tm , tm . , tm . , tm . , tm and tm composites under visible irradiation ( mg/l mo solution) yao et al. nanoscale research letters ( ) : page of the degradation reaction. therefore, the principal active species of photocatalytic degradation are photogenerated holes (h+), followed by hydroxyl radicals (•oh). the d/ d heterojunction of r-scheme ti c mxene/mos is beneficial to the migration and aggrega- tion of electrons from conduction band of mos to the active sites of ti c , thus accelerating the photocatalytic hydrogen evolution process. figure a presents a com- parison of h production activities with different tm samples under visible light irradiation. the pure mos (tm ) sample shows a poor photocatalytic hydrogen production rate ( . μmol h− g− ) due to the rapid re- combination of photocarrier. the rates of photocatalytic h production are significantly increased after coupling with ti c nanosheets, indicating that the electron ac- ceptors of d ti c mxene can effectively enhance the electron mobility. the optimal loading of ti c in ti c mxene/mos composites is . wt%, in accordance with the h production rate of . μmol h − g− . however, the rates of hydrogen production increase with ti c loading up to . wt% and then decrease at a higher ti c loading. the hydrogen production rates of tm and tm samples are . and . μmol h− g− , re- spectively. the reduction of hydrogen evolution rates at higher ti c loading can be described as the excessive ti c mxene shielding mos from the visible light. fig. a the photocatalytic hydrogen evolution rate of tm , tm . , tm . , tm . , tm and tm samples under visible light irradiation. b the recycling tests of tm . for water splitting process fig. a energy level structure diagram of mos and ti c . b schematic illustration of photo-induced electron transfer process at the heterojunction interface yao et al. nanoscale research letters ( ) : page of furthermore, the recoverability of tm . photocata- lyst is further analyzed by cyclic photocatalytic hydrogen production tests. as depicted in fig. b, the h produc- tion remains stable after cycles with h intermittence reaction under irradiation, which suggests that ti c / mos composites have strong stability. the probable mechanism of photocatalytic reaction over d/ d heterojunction of r-scheme ti c mxene/ mos can be demonstrated in fig. a. the photo- induced electrons arise from the vb of mos and trans- fer to the corresponding cb under visible irradiation. photoelectrons can transfer quickly from conduction band (cb) of mos to ti c by close-contact hetero- junction due to the greater activeness of the ef of ti c than the cb potential of mos [ ]. in a typical degrad- ation process, a large number of electrons accumulated on the surface of ti c mxene reacted with oxygen (o ) to produce superoxide radicals (•o −). meanwhile, the hydroxyl ions (oh−) and water adsorbed onto the catalyst surface reacted with photogenerated holes to generate hydroxyl radicals (•oh) [ ]. the steps of photocatalytic h evolution reaction are depicted by eq. ( )-( ) on the active rites of ti c : h o þ þ e− þ �→h� þ h o ð Þ h o þ þ e− þ h�→h þ h o ð Þ h� þ h�→h ð Þ the active sites can be represented by * in her process. the surface terminations of ti c mxene absorb h o + ion and electron to form an h atom, which is called vol- mer reaction, as presented in eq. ( ). the h atom com- bines with an electron from ti c and another h o + to form a hydrogen molecule, which is known as the heyr- ovsky mechanism, as depicted in eq. ( ). a h molecule is formed by two h atoms on the active sites, which is called the tafel mechanism, as displayed in eq. ( ) [ ]. the d/ d heterojunction of tm samples is illus- trated in fig. b. the photogenerated electrons can rap- idly migrate from mos to the surface of ti c nanosheets due to the electronic transfer channel of d/ d heterojunction. the excellent electronic conductivity of d ti c can effectively extend the separation time and reduce the recombination of photogenerated elec- tron hole pair [ ]. therefore, the photocatalytic activity is enhanced obviously. conclusions in summary, d/ d heterojunction of r-scheme ti c mxene/mos composites is successfully synthesized by hydrothermal method. the ti c mxene/mos photo- catalysts display remarkably enhanced photocatalytic ac- tivity for the degradation of mo and h evolution reaction compared with pristine mos . the . wt% ti c mxene/mos sample reaches an optimum mo degradation of . % after min irradiation and hydro- gen evolution rate of . μmol h− g− under visible ir- radiation. the morphology and structure analysis confirm that mos nanosheets are induced by ultrathin ti c mxene from crouching to stretching, which may greatly increase the specific surface area and enhance the light absorption ability. more importantly, ti c mxene coupled with mos nanosheets can effectively receive and transfer electrons from excited semicon- ductor, which is beneficial to suppress the charge recom- bination and improve the interface charge transfer processes. in this work, the constructed novel d/ d heterojunction of r-scheme ti c mxene/mos demon- strates that ti c mxene can become a promising co- catalyst in photocatalytic reaction. supplementary information supplementary information accompanies this paper at https://doi.org/ . /s - - -z. additional file : figure s . the xrd of raw ti alc and ti c . figure s . (a-d) shows eds mapping of mo, ti and c elements of tm sample; (e) eds analysis of tm . . figure s . the edx analysis of tm . sample. figure s . eis spectra of tm , tm . and tm powders. figure s . ft-ir spectra of tm and tm . . figure s . tem (a-b) and hrtem (c-d) images of tm and tm samples. figure s . (a) comparison on photocatalytic performance of tm . with various concentration of mo solution ( / / mg/l); (b-c) temporal uv-vis absorption spectra of and mg/l mo solutions after being illuminated by visible light in the presence of tm . sample, respectively. figure s . the xrd patterns of used and fresh tm . sample. table s . different tio -based composites for photocatalytic degradation of mo under visible light irradiation. abbreviations xrd: x-ray diffraction; sibs: sodium-ion batteries; her: hydrogen evolution reaction; tm: ti c mxene/mos ; fesem: field emission scanning electron microscopy; eds: energy-dispersive spectrometry; hrtem: high resolution transmission electron microscopy; ftir: fourier transform infrared spectroscopy; drs: uv-vis diffuse reflectance spectroscopy; xps: x-ray photoelectron spectroscopy; eis: electrochemical impedance spectroscopy; stem: scanning transmission electron microscopy; edta: triethanolamine acknowledgements this work was supported by the national natural science foundation of china (grant nos. u , ), innovation and development project of zibo city ( cx a ), instruction & development project for national funding innovation demonstration zone of shandong province ( - - , - - , - - , zcqzb , zcqzb ), central guiding local science and technology development special funds (grant nos. ), and key research & design program of shandong province ( ggx ). for table of contents only in this work, novel d/ d heterojunction of r-scheme ti c mxene/mos nanosheets is successfully synthesized by hydrothermal reaction. the ti c mxene/mos shows stronger light absorption, specific surface area, photo- current response, and smaller electrochemical impedance. above all, the strong interaction between mos and ti c mxene favors to construct d/ d heterojunction, which effectively promote the separation and transfer of photoelectrons. the . wt% ti c mxene/mos sample reaches an optimum methylene orange (mo) degradation of . % and h evolution rate of . μmol h− g− . this work also demonstrates that ti c mxene could be yao et al. nanoscale research letters ( ) : page of https://doi.org/ . /s - - -z https://doi.org/ . /s - - -z a promising carrier to construct d/ d heterojunction in photocatalytic deg- radation and hydrogen evolution reaction. authors’ contributions all authors have read and agree to the published version of the manuscript. ziyu yao and huajun sun conceived and designed the experiments; ziyu yao and xiaofang liu participated in the experiments and measurements; xiaofang liu and huiting sui participated in the discussion of the results; ziyu yao and xiaofang liu drafted the manuscript. availability of data and materials all data generated or analyzed during this study are included in this published article and its supplementary information files. competing interests the authors declare no conflict of interest. author details state key laboratory of silicate materials for architectures, wuhan university of technology, wuhan , people’s republic of china. school of materials science and engineering, wuhan university of technology, wuhan , people’s republic of china. advanced ceramics institute of zibo new & high-tech industrial development zone, zibo , people’s republic of china. school of chemistry, chemical engineering and life sciences, wuhan university of technology, wuhan , people’s republic of china. received: december accepted: march references . bhatkhande ds, pangarkar vg, beenackers aacm ( ) photocatalytic degradation for environmental applications - a review. j chem technol biotechnol : – . hernández s, hidalgo d, sacco a, chiodoni a, lamberti a, cauda v, tresso e, saracco g ( ) comparison of photocatalytic and transport properties of tio and zno nanostructures for solar-driven water splitting. phys chem chem phys : – . liu y, lee jhd, xia q, ma y, yu y, lanry yung ly, xie j, ong cn, vecitis cd, zhou z ( ) a graphene-based electrochemical filter for water purification. j mater 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institutional affiliations. yao et al. nanoscale research letters ( ) : page of 	abstract 	introduction 	method/experimental section 	photocatalysts preparation 	raw materials 	synthesis of ti c nanosheets 	hydrothermal preparation of ti c mxene/mos (denoted as tm) composites 	photocatalytic degradation of methylene orange 	photocatalytic hydrogen production evaluation 	microstructure characterization 	electrochemical measurements 	results and discussion 	conclusions 	supplementary information 	abbreviations 	acknowledgements 	for table of contents only 	authors’ contributions 	availability of data and materials 	competing interests 	author details 	references 	publisher’s note hdjnm_ .. editorial nanostructure materials as a promising route for efficient renewable energy production, storage, and conversion nour f. attia , , slama sami, sally e. a. elashery, and jamal siddiqui fire protection laboratory, chemistry division, national institute for standards, , giza , egypt department of energy engineering, gyeongnam national university of science and technology (gntech), jinju , republic of korea jeddah community college, king abdulaziz university, jeddah, saudi arabia chemistry department, faculty of science, cairo university, gamaa str., giza, egypt department of chemistry, school of basic sciences and humanity, lingaya’s university, india correspondence should be addressed to nour f. attia; drnour @yahoo.com received january ; accepted january ; published january copyright © nour f. attia et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. the rapid growth of worldwide population in conjunction with expansion in industry sectors in the world attributed to huge consumption of limited stock fossil fuels. hence, this expected energy crisis forced the world to find a clean renew- able source of energy instead of consumable fossil fuel one. therefore, there are intensive efforts to use solar energy, wind energy, and hydrogen energy. however, the production, stor- age, and conversion of these kinds of energy sources require development of smart materials to facilitate their rapid com- mercialization. on the other hand, the nanomaterials have received intensive scientists’ interest for various applications due to their outstanding chemical, physical, mechanical, elec- trical, and electronic properties. hence, the harness of unique properties of materials and their hybrid nanocomposites will be much appreciated and demanded to be used in energy- related applications such as production, storage, and conver- sion. therefore, in this special issue, we invited the scientists and researchers all over the world to submit their original novel work based on nanomaterials for solar cells, fuel cells, hydrogen storage and production, hybrid nanocomposites, and supercapacitors. in conclusion, we are happy to announce the publication of four original research papers and one review in the field of nanostructure materials as a promising route for efficient renewable energy applications. conflicts of interest there is no conflict of interest to declare. acknowledgments the lead guest editor would like to thank all authors who contributed in this special issue and the scientists who reviewed the manuscripts, also the guest editors who shared their time and effort to have this issue published. nour f. attia slama sami sally e. a. elashery jamal siddiqui hindawi journal of nanomaterials volume , article id , page https://doi.org/ . / / https://orcid.org/ - - - https://creativecommons.org/licenses/by/ . / https://doi.org/ . / / 	nanostructure materials as a promising route for efficient renewable energy production, storage, and conversion 	conflicts of interest 	acknowledgments mathematical modeling and simulation of anaerobic digestion of solid waste procedia technology ( ) – available online at www.sciencedirect.com sciencedirect - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of icetest – doi: . /j.protcy. . . international conference on emerging trends in engineering, science and technology (icetest - ) mathematical modeling and simulation of anaerobic digestion of solid waste manjusha ca, sajeena beevi.bb* amtech student, chemical engineering department, government engineering college thrissur, thrissur, india bassistant professor, chemical engineering department, government engineering college thrissur thrissur, india abstract waste management and energy crisis are the greatest issues that the world is facing today. this problem can be overcome by anaerobic digestion of solid waste, where the waste is converted to biogas: a mixture of mainly carbon dioxide and methane gas. because of the growing need of anaerobic digestion of solid waste, increased efforts in reducing biogas plant design cost and optimizing process operation is crucial. one way of doing this can be through mathematical modeling of the anaerobic process. the purpose of this paper is to use the anaerobic digestion model no. (adm ), which gives complete information about the physico-chemical reactions in the anaerobic process, to investigate how different parameters in the model affect biogas production. a model was implemented in matlab and can be used to find out how the factors such as ph and volatile fatty acid (vfa) affect the daily biogas production. © the authors.published by elsevier ltd. peer-review under responsibility of the organizing committee of icetest – . keywords: anaerobic digestion; biogas; adm matrix; . introduction energy crisis and waste management are the major issues that the world is facing today. in order to overcome this problem, an efficient way of technology is needed. organic fraction of solid waste is required to manage in such a way as to minimize the negative environmental impact, fewer hazards to human health and maintain ecological balance. anaerobic digestion of solid waste is an effective technology that treats different types of organic waste. * corresponding author. tel.: + ; fax: + - - . e-mail address:sajeenanazer@gmail.com © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of icetest – c. manjusha and b. sajeena beevi / procedia technology ( ) – the main advantages of anaerobic digestion of solid waste are in terms of energy, cost, and ecological balance, which make this technology much better than other conversion process [ ]. different types of systems are available for the treatment of solid waste through anaerobic digestion, such as batch process, continuous process, single stage and multi stage process. the anaerobic digestion is one of the innovative technologies in the field of waste treatment. there are several varieties of researches undergoing in the field of waste treatment. the main aim of these researches is to analyze the parameters that will affect the production of biogas. there are a number of factors that affect the production of biogas, such as ph, volatile fatty acid, temperature, quantity of substrate being used, and alkalinity. the level of these factors must be in correct proportion in order to keep the production of biogas in a particular level. anaerobic digestion of solid waste is limited in developing countries due to the lack of proper treatment systems. designing of reactor and selection of operational criteria depend on substrate characteristics and cost. the anaerobic digestion of solid waste has a lot of applications over other conversion techniques. however, each mode of operation always has its own advantages and disadvantages. the purpose of this study is to develop a mathematical modeling of anaerobic digestion of solid waste and optimize the environmental condition such as ph, volatile fatty acid, temperature for increasing the biogas production in a shorter retention time. dynamic modeling and simulation is increasingly being employed as an aid in the design and operation of waste treatment especially in europe. but most developing countries like india are still following conventional design technique based on the static models or empirical formulae derived either from past pilot scale studies or from performance of already existing waste treatment plant elsewhere. a dynamic model can be a useful tool for the prediction of process performance in transient conditions and for a better understanding of the process and its optimal working conditions. the main objective is to develop a mathematical model for the batch study of anaerobic digestion of organic fraction of municipal solid waste (ofmsw). to achieve this objective we are adapting the default adm for modeling and simulation of anaerobic digestion of organic fraction of municipal solid waste and calibrating the model using lab scale data from the batch study. . mathematical modelling and simulation of batch reactor . . anaerobic digestion model no (adm ) because of the growing need in anaerobic digestion of solid waste, increased efforts in reducing biogas plant design cost and optimizing process operation is crucial. one way of doing this can be through mathematical modeling of the anaerobic process. this is a fact that has been recognized by researchers for a long time. between the years and there have been about publications concerning mathematical modeling of anaerobic digestion. but evaluating the merits of every scientific model on anaerobic digestion available would be a daunting task. therefore, in recognizing both the great potential benefits of a functional model and the need of a more widely accepted mathematical description of the anaerobic process, the international water association (iwa) formed a task group aiming at the creation of a mathematical model of anaerobic digestion. quoting batstone et al ( ), the full aims of the so called “anaerobic digestion model no. ” (adm ) [ ] are: increased model application for full scale plant design, operation and optimization, further development work on process optimization and control, aimed at direct implementation in full scale plants, common basis for further development and validation studies to make outcomes more comparable and competitive, and assisting technology transfer from research to the industry. the adm model describes the five main biochemical steps (involving biological enzymes) in an anaerobic digester. it starts with disintegration, followed by hydrolysis, acidogenesis, acetogenesis and methanogenesis. seen in fig. .the process can be described by the following steps: in the disintegration step, complex biomass molecules are broken down to lipids (i.e. fats), carbohydrates and proteins. in hydrolysis, molecules of carbohydrates, lipids and proteins are broken down to long chain fatty acids (lcfas) amino acids and sugars. in acidogenesis, these lcfas, amino acids and sugars are broken down to volatile fatty acids (vfas), namely propionate, valerate, butyrate and some acetate. these vfas are then transformed into acetate in the acetogenesis. this acetate is finally transformed into methane gas and carbon dioxide, in the methanogenesis. all in all, there are different compounds taken into account by the adm model. an important group of components in the adm model is biomass (i.e. anaerobic bacteria groups). in the adm model, there are seven types of biomass [ ] that degrade eight different components (long chain fatty acids, amino acids, sugars, valerate and butyrate, propionate, acetate and hydrogen). these biomass groups have different sensibilities to process disturbances. these disturbances are referred to as inhibition. inhibition occurs when the uptake of a compound and growth of biomass is decreased. this can lead to a less efficient process, with lower methane yields or even a c. manjusha and b. sajeena beevi / procedia technology ( ) – complete process failure. the adm model comes in its default setting with inhibition factors describing major inhibition processes[ ], namely ammonia inhibition, hydrogen inhibition, ph inhibition, competitive inhibition (competition between valerate and butyrate utilizers for valerate and butyrate) and secondary inhibition (competition for nitrogen between biomass groups). the ph dependence of ammonia is also included since a rise in ph displaces the ammonia-ammonium balance towards ammonia. ammonia inhibition is strongly linked to the composition of the waste. excess nitrogen, for example from high protein contents, can be converted into ammonia and that would inhibit the process. this ammonia can be created provided that the biomass (anaerobic bacteria) cannot use nitrogen in their cellular metabolism because of lack of carbon. fig. .the disintegration and biochemical steps in the adm model after the release of the adm model, many authors have showed that it possesses good predictive capabilities for different configurations of anaerobic digestion processe. also, when published, the intent of the adm was to model steady state processes; it has however been shown that a dynamic loading regime, in terms of varying masses of waste, is not a great difficulty for the model. it is common practice for authors to implement changes in the default adm model to achieve a closer fit to data. the adm model comes with a large set of constants, and recommended values for these constants are found in the adm publication. it is a common practice among researchers to change the values of one or more of these constants to achieve a closer fit to data. adding inhibition terms are another common practice among authors. additional inhibition factors than those used in the default adm publication can be taken into account in addition to the adm model. a particular problem with the default ph inhibition function mentioned in batstone et al ( ) is that it is discontinues and may cause numerical instabilities. similar ph functions have therefore been devised for the adm model which “mimics” the original function without these instabilities the adm only utilizes the so called first order kinetics, since all differential equations in the adm model are first order equations. the adm model can be implemented as either a system of differential equations (de- implementation) with state variables in total, i.e. variables described by separate differential equations, or using differential equations and algebraic equations (dae-implementation) with state variables in total [ ]. in both implementations some compounds are counted twice since they exist both in gas and liquid phase, or are divided into acid base pairs. the idea behind the dae implementation is that it removes stiffness from the implemented system. a system is stiff when the range of time constants is large. in essence, this means that some state variables change very rapidly, such as acid base pairs, while some change much more slowly, such as biomass. stiff systems demand special c. manjusha and b. sajeena beevi / procedia technology ( ) – solvers to solve computationally. these solvers can be quite slow when transient (variation with time) loads are simulated. . . batch reactor model the adm model was implemented using differential equations to describe the state variables. it was coded and implemented in matlab and solved with the variable step size, using euler method solver ode s for differential equation systems. the main assumptions to be considered during the modeling are - the reactor is well stirred, there are no effects due to fluid motion in the digester, temperatures in the reactor are considered to be the same in all parts of the digester, and hydrolysis constants were at least a factor ten lower than in the default adm model. fig. . process model equations in liquid phase for batch reactor there is no inlet and outlet. so its liquid volume is kept constant. according to the mass balance, the state of each component in liquid phase can be expressed as follows [ ] v ij j j iliq dt ds , ( ) where vij is a stochimoetric constant in the adm matrix. the process rate for process number j is given as j, it is found in the right column of the matrix and is determined by multiplying the process rates ρj for all process j with the specific vij in the matrix for the specific i. equations in gas phase according to the mass balance, the state of each component in gas phase can be expressed as follows gas it gas igasigasgas,i vv qs dt ds vliq , ,, * ( ) where q is the gas flow rate for gas i (i=hydrogen, carbon dioxide, methane gas). the transfer rate of gas is i ρt,i, where i is temperature specific, with concern to the henry’s law coefficient kh, i. transfer rates are calculated according to: , , , , * ( hgashhhliqlaht pksk ) ( ) c. manjusha and b. sajeena beevi / procedia technology ( ) – , , , , * ( chgaschhchliqlacht pksk ) ( ) )* ( , , , , cogascohcoliqlacot pksk ( ) here, pgas,i is the partial pressure of gas i, which can be calculated with the ideal gas law equation of state. kh, i is the henry’s law coefficient for gas i, for temperature t. assuming that gas flow is restricted through an orifice, the gas flow, qgas becomes: p p p gas atm gas atmpgas pkq *)( ( ) . results and discussion . . performance of batch reactors the plot of daily biogas production versus days is shown in figure (a). initially biogas production is high due to the present of air inside the reactor and waste [ ]. fig. . (a) biogas vs days; (b) vfa vs days; (c) ph vs days the maximum daily biogas production is obtained was ml on th day. the biogas production was decreased at c. manjusha and b. sajeena beevi / procedia technology ( ) – the end of days due to the lack of substrate. under optimized condition daily biogas production obtained was . l.this shows that optimization of the process parameter will give higher biogas production. on increasing the concentration of substrate, biogas production is high due to the accumulation of substrate. biogas production is low on decreasing the concentration due to the lack of substrate. the plot of vfa versus days is shown in figure (b). initially vfa accumulation is very low. at the end of the digestion it increases to high value due to acidification of vegetable waste. it may reduce the ph and cause the decrease in the free ammonia and inhibition of methanogenesis. from the plot it is clear that maximum volatile fatty acid was obtained at th day of experiment. due to the rapid acidification of vegetable wastes high vfa may form, and that leads to the instability of the reactor. at the initial condition vfa is very low. the plot of ph versus days is shown in figure (c). ph was almost steady from days to . after that the ph value gets changed due to accumulation of fatty acid and ammonia nitrogen. in anaerobic digestion process ph should be maintained at . to . , which is the optimum range for methanogensis process. ph was found to be decreasing during the initial days of digestion due to the formation of volatile fatty acid. in the middle of the total days ph was maintained at . after that the ph value changed due to the accumulation of volatile fatty acid and ammonia nitrogen . conclusion anaerobic digestion of solid waste is a complex process involving various microorganisms and substrate. model contains unknown parameters which have to be estimated from experimental data. based on the performance of anaerobic digestion of solid waste maximum biogas production was obtained at total concentration of g/l. it is observed that on decreasing the concentration biogas production was reduced due to the lack of substrate. on increasing the concentration, the production was high due to the accumulation of large amount of substrate. simulation of anaerobic digestion of solid waste was done by using mat lab. in this work, a modified version of adm model was proposed to model and simulate anaerobic digestion of batch study. numerical simulations have then been used to evaluate the performance of anaerobic digestion of solid waste. appendix nomenclature variable description vfa volatile fatty acid ρt,i specific mass transfer rate of gas i kla overall mass transfer coefficient kl times the specific transfer area sliq.i concentration of gas i in liquid phase pgas,i partial pressure of gas i in gas phase (bar) kh,i henry’s law coefficient of gas i (mole/m /bar) kp pipe resistance coefficient sgas.i concentration of gas i in gas phase r gas law constant ( . · - bar·m /mole/k) t absolute temperature (k) c. manjusha and b. sajeena beevi / procedia technology ( ) – acknowledgements the authors thank the principal, head of the department of chemical engineering, project guide mrs sajeena beevi b of government engineering college, thrissur for their help and support. references [ ] bastogne, d .j., keller, j., angelidaki, i., kalyuzhnyi, s.v., pavlostathis, s.g., rozzi, a., sanders, w.t.m., siegrist, h. & vavilin, v.a.( ) the iwa anaerobic digestion model no. . water science and technology ( ) - . [ ] batstone d.j. ( ) mathematical modeling of anaerobic reactors treating domestic wastewater: rational criteria for model use. reviews in environmental science and bio and technology ( ) - [ ] jose p.p bioenergy conversion studies of organic fraction of muncipal solid waste, ‘international journal of scientific and research publications, ( ), pp. - [ ] alina haqgelqvist, methane yields from anaerobic digestion of food waste variation of load, retention time and waste composition in simulating methane yields, using the “anaerobic digestion model no. ” (adm ) [ ] christian wolf, simulation, optimization and instrumentation of agricultural biogas plants [ ] bhunia, p., ghangrekar, m.m., .analysis, evaluation and optimization of kinetic parameters for performance appraisal and design of uasb reactors .bioresource technology ( ), e . [ ] zaher, u., vanrolleghem, p., rodriguez, j., franco, a., .conceptual approach for adm applications. in: ujang, z., henze, m. (eds.), environmental biotechnology: advancement in water and wastewater applications in the tropics. [ ] zaher,u.,pandey, p.,chen.s., . a simple elemental continuity based model application to study the anaerobic microbial activity for the treatment of dairy manure. applied mathematical modelling ( ), e [ ] hansen, k, angelidaki, i, ahring, b.k, anaerobic digestion of swine manure: inhibition by ammonia. water res. ( ) ( ) – . [ ] metcalf & eddy, inc., wastewater engineering: treatment and reuse thed. mcgraw-hill, new york, [ ] volcke, e.i.p., van hulle, s., deksissa, t., zaher, u. and vanrolleghem, p.a. ( ). calculation of ph and concentration of equilibrium components during dynamic simulation by means of a charge balance. biomath tech. report, ghent university, ghent, belgium [ ]gallert, c, henning, a, winter, j, scale-up of anaerobic digestion of the biowaste fraction from domestic wastes, water res. ( ), – . [ ] gernaey, k.v., rosen, c and jeppsson, u. ( ). wwtp dynamic disturbance modeling - an eesential module for long-term benchmarking development. wat. sci. tech. ( - ), - [ ] copp j.b. (ed.) ( ). the cost simulation benchmark - description and simulator manual. isbn - - - , office for official publications of the european communities, luxembourg. [ ] a. del borghi, a. converti, e. palazzi and m. del borghi, “hydrolysis and thermophilic anaerobic digestion of sewage sludge and organic fraction of municipal solid waste”, bioprocess eng., vol. , pp. - , . universities council on water resources journal of contemporary water research & education issue , pages - , june integrated policy and planning for water and energy young-doa wang associate director, center for energy and environmental policy; professor and director, energy and environmental policy program; professor, school of urban affairs and public policy, university of delaware w e are faced with chronic water and energy vulnerabilities. sonle argue that we will face two crises in the ] st century: a water crisis and an energy crisis (brown , , flavin , feffer ). water will become increasingly scarce as water tables drop due to over-consumption and water quality will continue to deteriorate as a result of excessive contamination. further, the present energy regime's dependence on non-renewable sources has added considerable stress to the environlnent, including the prospect of climate change (intergovernmental panel on climate change ). we are amidst a situation where we could be easily blamed for compromising the ability of future generations to meet their needs. this paper first briefly describes a need for understanding the integrated considerations of water and energy in resource planning, especially during droughts. after introducing a conceptual framework of the water-energy integration, this paper reviews the results of a national survey of energy and water departments to see how these synergic benefits are explored at the state level. lessons learned from our case studies serve as useful guidelines for state water-energy planning and program development. finally, as an exanlple case of the water-energy nexus~ the concept of desalination is introduced with its iltiplication on energy demand. energy-water nexus: an e framework given the present context, there is a need for a greater understanding of energy-water linkages in order to develop more effective policies to address their mutual vulnerabilities. i envision that the approach to resolving the issue will have journal of contemporary water research & education to be an integrated one that exploits the synergies between the energy and water sectors. synergic benefits derived from water and energy integration are especially significant during droughts, which are expected to intensify from global warming, which is, in turn, primarily the result of fossil fuel consumption. the main challenge that these integrated po licies will have to address is to provide sufficient clean fresh water while maintaining adequate energy supplies to sustain healthy and secure societies and ecosystems. following the lj.s. energy policy act of , the department of energy's national laboratories and the electric power research institute initiated a multi-year \vater- energy progran , expected to cost $ million annually until , encompassing research and developltient and outreach. although the inter-and intra-sectoral interaction between water and energy is much more complicated, figure ] presents the linkages in a silnplified version. it is shown that water use affects primarily the generation and consumptive aspects of the energy sector, whereas~ energy utilization ilnpacts all aspects of the water sector. in california, around percent of all energy consunled is attributable to the co] lection, extraction, conveyance, distribution, use~ and treatment of water (house ). the production of energy from fossil fuels and nuclear power is inextricably linked to the availability of adequate and sustainable supplies of water for cooling. in the u.s., thennoelectric power generation is one of the biggest users of water, accounting for percent ( billion gallons per day) of total water withdrawals in (u.s. department of energy ). as a result of these linkages there is the potential for benefits to be accrued if an integrated ucowr wang [~:~t:~~t] [cdnsum ptid n /~ energv i figure . a water-energy integrated framework. approach is irrlplemented in the management of both sectors. the integration of water and energy sector planning and management can have positive inlpacts on the economy, environment, energy, and equity (e ). water and energy conservation improves the e balance, enhancing sustainability, particularly during drought events in urban areas (smith and wang , wang et al. ). many of these benefits are interlinked and depend on the extent of the itnplementation of efficiency improvements that are possible through integration. the franlework in figure conceptualizes the benefits of integration from the perspective of e gains, especially during drought periods. the efficient use of water and energy can result in lower utility bills for customers and bring other long term societal benefits as it can reduce or even elilninate the need for costly supply-side facilities or waste water and sewage facilities (featherstone , u.s. epa , wang, et al. ), together with lowering the cost of managelnent of droughts (econolny). the efficient use and reduced wastage of water will lower the amount of energy needed to supply water, in addition to a concurrent reduction in pollution elnissions from power plants (wang et al. ). conservation measures, as well as the efficient ucowr figure . increased water-energy integration benejits during drought periods. journal of contemporary water research & education integrated policy and planning for water and energy use ofwater wi also benefitthe environnlent as they will reduce the need for withdrawal from surface and ground water supplies" thereby increasing the availability of surface and ground water supplies for ecological functions and restricting salt water intrusion into coastal areas (center for energy and environmental policy l. u.s. environlnental protection agency ) (environlnent). in the u.s., approxinlately percent of all electricity consumed is used to deliver water and treat waste water (house ). in california, water-related energy use, including water pumping for irrigation., consumes percent of the state "s electricity, percent of its natural gas, and billion gallons of diesel fuel annually (house ). when users adopt '\later-efficient appliances, energy consumption is reduced in two ways: directly, by the appliances thejtiselves and indirectly as water utilities use less energy for surface and ground water withdra~val and waste water treatment and discharge (cohen et al. ., u.s. environmental protection agency ). conservation at the tailpipe end stage elitninates all of the ·'upstrean " energy required to bring the water to the point of end use, as wel as al of the ~'downstream" energy that would otherwise be spent to treat and dispose of this water (cohen et al. ) (energy). conserving water and energy increases their availability, which makes it easier to optimize their allocation between competing users (wang et al. ), especially during droughts. successful conservation efforts will reduce conflicts over in-strean flow rights and competing uses of water, including down stream power generation sectors that are occun'ing with increasing frequency (vickers ) (equity). national survey and lessons learned a survey conducted by the center for energy and environmental policy ( ) across all the u.s. states' energy and water departments found that only three states (california, new york, and wisconsin) had some kind of integrated water- energy programs (wang et al. ). nine states had limited programs or were part of a regional initiative focusing on the issue of water and energy interactions (alaska, connecticut~ hawaii, idaho, maine, nebraska, nevada, new mexico, texas and virginia). eleven states responded that they did journal of contemporary water research & education not have any integrated energy-water programs, and the remaining states did not respond, but a rigorous search of the literature and state websites suggested that there were no integrated energy- water programs in those states. here resides a fertile place for future academic exploration. integration of water and energy is demonstrated to enhance e aspects, but synergic benefits of the integration are not fully explored at the state level even with federal initiation. an important question would be why they are not fully explored and implemented. the three cases of california, new york, and wisconsin provide some answers to the question in the three areas of information, planning and institutional coordination, and funding. impacts of efficiency improvements and alternative technological developments in both water and energy production on the synergic benefits need to be fully understood, especially in regards to drought events. this becomes all the more important considering that the six hottest years on record have occurred in the last ten years (goddard institute for space studies ), thus making us more prone to a vicious cycle of droughts or other natural calamities. the federal water-energy initiation needs to be tailored to meet the specific needs of state. coordination within the state includes engagement between energy utilities and water providers directed by the public service commission, statewide public-private partnerships, and the combining of water and energy audits. water-energy integrated prograltis can be funded by public benefit charges. these are ancillary charges levied by an energy or water utility on its custonlers. further examples of program specifics include: ) information dissemination is a key tool for initiating integrated water-energy planning. by sponsoring workshops, undeltaking research, and developing websites, the state could begin the process of building public interest in water-energy conservation. education ofk- and college students about integrated conservation of energy and water opportunities could be specifi cally developed. ) a pilot program in california has been used to evaluate the energy ittipacts of water ucowr wang resources. it also analyzed water-energy savings in the commercial, institutional, and industrial sectors, and evaluated the impact ofa renewable portfolio standard (rps) on water resources. states could also undertake research to evaluate the inlpact on water resources in achieving their mandatory rps target. ) water-energy conservation partnerships have been formed in the case study states to address water and energy issues. the partnerships offer services to a range of sectors including agriculture, commercial, industrial, schools, and local government. members of the partnerships include private and public energy and water utilities (including wastewater utilities), customer- based organizations, environmental groups, consultants, universities and various state agencies. ) technical and financial incentives, tax incentives, rebates, and system benefits charges have been used in the case study states to support integrated water-energy planning. these and other financial lnechanisms could be used to promote and attain benefits associated with integrated water-energy conservation. ) in the case study states, no legislation has been enacted to promote water-energy integration except for regulations on thermal discharges of water by power plants. however, green building standards, which generally focus on measures to reduce energy use, can also address water use, including water conservation. ) combining energy and water audits for large customers, including industrial process units., has proven effective in the case study states. metrics for quantifying energy savings from water conservation and efficiency in water utility supply and conveyance, treatment, distribution, end use, and waste water treatment have been carefully defined in california, wisconsin and ne",r york. desalination one area which clearly reveals the water-energy ucowr nexus is the desalination of brackish and seawater sources. desalination efforts are fueled by growing concerns over increasingly expensive, unavailable, or controversial traditional sources of water supply. the high cost, environmental impacts, and energy requirements of desalination are tnain concerns. the cost issue is no longer the primary barrier because of significant technological advancenlent and reductions in production costs (the national academies press ), but the energy requirement is still a major issue. even though efficiency improvements in membrane technologies reduce the energy needed to desalinate water, it is essential to look for energy-efficient ways to produce desalted water (darwish et al. ). thennally driven desalting systems from fuel-fired boilers are the most inefficient practice in terms of environment, energy, and econonlic perspectives. desalination offers a great potential to the people living in coastal areas, serving around percent of the world's coastal population. this energy- intensive technology mostly mushrooms, especially in the water-poor but energy-rich nations of the persian gulf. the technology is now taking off in the european union including spain (meerganz von medeazza et al. ). if fossil fuel prices increase as predicted by pessimistic scenarios and the carbon tax is enforced, the cost advantage for nuclear desalination will be pronounced (methnani m. ). the favorable economics of nuclear desalination may not be sufficient enough to overcollle technological risks and the socio-political resistance against nuclear power and disposal of its wastes. the desalination of seawater using renewable energies is an alternative option, but the conversion of renewable energies requires high investment cost and the technology is not yet mature enough to accommodate large-scale applications (mathioulakis et a . ). in recent years, technological innovation in solar energy and a concurrent improvement in solar econolnics offer prolllise in the field of desalination by renewable energies, especially with solar energy applications. a fundamental shift either in energy prices or in membrane technology could bring costs down substantially. development of membranes that operate effectively at lower pressures could lead journal of contemporary water research & education integrated policy and planning for water and energy to to percent of process cost reductions due to a percent decrease in energy demand (national research council ). if either happened to the extent that the marginal cost allowed for agricultural in"igation with sea water (around us$. /m on average), some portion ofthe world's water supplies would shift froln rivers and shallow aquifers to the sea. besides the fundalnental economic changes which would result, geopolitical thinking about water systems would also need to shift. many which are currently dependent on upstream neighbors for their water supply, would, by virtue of their coastlines, suddenly find these roles reversed. conclusion water and energy resources are essential to hulnan survival. a general conclusion of the analysis of the energy-water conservation programs exanlined in this paper is that a wide range of knowledge, receptivity~ and applications of practices and programs can alleviate stresses on both the water and energy sectors. additionally, the assessment of these programs reveals that integrating energy and water planning has the potential to save money, reduce waste, protect the environment, ilnprove equity, and strengthen the economy. states could utilize elenlents of progranls and planning approaches similar to those discussed in the case study states and use such approaches as models to assist in the construction of new frameworks for the integration of water and energy conservation. 'the need for this integration seems all the more important in light ofthe recent droughts, the potential for more extreme weather due to climate change, and the demonstrated economic, environmental, equity, and energy benefits of such an integration. intense desalination activity has been witnessed in the coastal areas of the world, including the arabian gulf, the mediterranean sea, the red sea, or the coastal waters of california, china., and,a.ustralia. despite the many benefits the technology could offer, concerns have arisen over the substantial energy demanded by the desalination process, along with potential negative inlpacts on the environment from returning the concentrated brine back to sea (lattemann et al. ). nuclear, journal of contemporary water research & education fossil fuel., and renewable energies can be used as input fuels in the process of desalination, but each energy source has its own issues in terms of e perspectives. nuclear faces socio-political resistance, fossil fuels emit air pollutants" and renewables are constrained by the high initial cost. the perception that desalination could meet ever-growing fresh water demands should be shifted. efforts to conserve water, use water more efficiently and recycle waste water are all the more important, and the extent of desalination should be restricted to the many semi-arid and arid coastal regions in the world suffering from structural water shortages. these and other issues related to water-energy integration will be one of the vibrant research agendas for the next couple of decades. notes . for instance, sandia national laboratory leads the national energy-water roadmap program. regional \;vorkshops have been held to identify specific regional issues and needs associated with the energy and water nexus. . his important to note that although water withdrawal for thermoelectric generation is very high, it consumes only about . percent of the \vater, the remaining being returned to the source albeit with environmental impacts as a result of changes to the \vater temperature. this does become critical in areas where the aquatic environnlent is highly sensitive to temperature changes especially during dry hot \veather. author bio and contact information young-doo wang, ph.d., is associate director of the center for energy and environmental pol icy at the ljniversity of delaware. he is professor and director of the energy and environmental policy graduate program, and professor in the school of urban affairs and public policy. i)r. wang isalso co-executive [)irectorofthejoint institute for a sustainable energy and environnlental future, an innovative institution promoting peaceful and sustainable energy policy options in northeast asia. }--ie has published over articles in the areas of energy, environment, and sustainable development policy. his recent books include energy revolution: tolit'ard an energy-f/ficient future ..for south korea (vvith john byrne et al.) and water conservation-oriented rates: strategies to extend supply, promote equity, and :v/eet a inimum j~~i j levels (with william stnith et al.). i--ie ucowr wang can be contacted at youngdoo@udel.edu. references center for energy and environmental policy. . securing delav/are s future through sustainable ~vater resources lvlanagelnent. university of delaware. cohen, r., b. nelson~ and g. wolff. . energy dolvn the drain: the f/idden costs of california ~~ ~vater supply. natural resources defense council, new york, ltsa. darwish, m. a., n. m. ai-najem, and n. liar. . to\vards sustainable seawater desalting in the (}ulf area. jjesalination ( ) - . featherstone, j. . conservation in the delaware river basin. journal of the alnerican t-vater tiorks association ( ): - . goddard institute for space studies. . global te perature anomalies. available at: http://data. giss.nasa.gov/gistemp/tabledata/glb.ts.txt. i-louse, w. l. . will water cause the next electricity crisis? tvater resources lnzpact ( ), january . latternann, s. and hopnert. . environmental inlpact and ilnpact assessment of sea\vater desalination. desalination ( ) - . mathioulakis~ e. et al. . desalination by using alternative energy: revie\v and state-of-the-art. [jesalination ( ) - . meerganz von .medeazza, ci. and v. moreau. . model ing of water-energy systems: the case of desalination. energy ( ) - . methnani~ m. . influence of fuel costs on sea'vvater desalination options. desalination ( ) - . national research council. . desalination: a lvational perspective. washington, d.c.: the national academies press. ljs i)()e/eia. . energy demands on water resources: report to congress on the interdependency of energy and water. available at: http://w\vw. netl.doe.gov/technologies/coalpower/e\vr/pubs/ i)() e% energy-water% nexus% report% to % congress% .pdf. tj.s. environmental protection agency. . ho\v to conserve water and use it effectively. available at: http://\vw'vv.epa.gov/ v.;lyou/chap .html. li.s. environrnental protection agency. . guidelines for rvater (~onservation plans. available ucowr at: http://www.epa.gov/ow/ webguid.html. vickers, a. . demand management and water efficiency. journal of the american fvaler n'orks association ( ): - . wang, y-d.~ g. alleng, j. byrne, · . conte, j. karki, s. rao, s. jose, j. demooy, a. belden, a. sood, and p. cole. . synergic benefits o..flntegrated ~vater and energy planning. presented to the rd association of american geographers annual meeting. san francisco, ca. april - . wang, y. d., w. smith, j. byrne, m. scozzafava, and j. song. . freshwater management in industrialised urban areas: the role of water conservation. in velma grover (ed.). water: ( lobal conlmoi and global problenls. plymouth~ nj: science publishers. pp. - . wang, y. d., w. j. smith jr., and j. byrne, j. . fvater c~onservation-oriented l?ates: strategies to expand suppzv, pron-lote equity and a/eel minilnuln f'lol j levels. american water works association. denver, co, ljsa journal of contemporary water research & education metformin and prostate cancer stem cells: a novel therapeutic target review metformin and prostate cancer stem cells: a novel therapeutic target mj mayer , , lh klotz , and v venkateswaran , prostate cancer is the second most frequently diagnosed cancer in the world. localized disease can be effectively treated with radiation therapy or radical prostatectomy. however, advanced prostate cancer is more difficult to treat and if metastatic, is incurable. there is a need for more effective therapy for advanced prostate cancer. one potential target is the cancer stem cell (csc). cscs have been described in several solid tumors, including prostate cancer, and contribute to therapeutic resistance and tumor recurrence. metformin, a common oral biguanide used to treat type diabetes, has been demonstrated to have anti- neoplastic effects. specifically, metformin targets cscs in breast cancer, pancreatic cancer, glioblastoma and colon cancer. metformin acts directly on the mitochondria to inhibit oxidative phosphorylation and reduce mitochondrial atp production. this forces tumor cells to compensate by increasing the rate of glycolysis. cscs rely heavily on mitochondrial oxidative phosphorylation for energy production. the glycolytic switch results in an energy crisis in these cells. metformin could be used to exploit this metabolic weakness in cscs. this would increase csc sensitivity to conventional cancer therapies, circumventing treatment resistance and enhancing treatment efficacy. this review will explore the characteristics of prostate cscs, their role in tumor propagation and therapeutic resistance and the role of metformin as a potential prostate csc sensitizer to current anticancer therapies. prostate cancer and prostatic diseases ( ) , – ; doi: . /pcan. . ; published online july introduction prostate cancer (pca) has a long natural history. when prostate cancer is localized and is classified as a low gleason grade tumor, it can be monitored with active surveillance. higher-grade cancers are effectively treated by surgical resection of the prostate (radical prostatectomy) or radiation therapy. , however, if the cancer invades through the capsule into surrounding tissue, or recurs after local therapy, it is much more difficult to treat. if the disease metastasizes, it is generally incurable. , advanced-stage pca is usually treated with androgen-deprivation therapy (adt). most patients with metastatic disease managed with adt eventually relapse with castration-resistant prostate cancer (crpc) and die of the disease. , crpc can be treated with docetaxel, abiraterone plus prednisone, enzalutamide, and cabazitaxel, which provide significant survival benefits, but are not curative. thus, there is still a need to improve the therapeutic options available for advanced-stage prostate cancer patients. prostate cancer is a multifocal disease. prostates often contain multiple independent and genetically distinct foci. one model that explains this heterogeneity is the ‘cancer stem cell’ model. this model postulates that only a small subset of cancer cells within a tumor have the ability to sustain tumorigenesis, resulting in a hierarchical organization of primary tumors. , this subset of tumor-propagating cells are defined as cancer stem cells (cscs), as they share a number of characteristics with normal stem cells, one such example being self-renewal. – cscs were first identified and characterized in hematological malignancies by bonnet and dick. since then, cscs have been identified in several solid tumors including breast, pancreas, colon, lung, brain and prostate. – the csc model is intriguing because it provides an explanation for tumor recurrence and resistance to conven- tional cancer therapies. the discovery of new agents that can sensitize cscs to conventional cancer treatments holds therapeu- tic promise. metformin, a common well-tolerated oral biguanide prescribed for type diabetes, has been shown to selectively target cancer stem cells in several types of solid tumors and improve the efficacy of radiation and chemotherapy in breast cancer and colon cancer. – targeting therapy-resistant cscs in prostate cancer provides a unique opportunity for novel therapeutic interventions. metformin could be used to sensitize prostate cscs to current conven- tional anticancer therapies and improve efficacy of treatment. this review evaluates the current evidence regarding the role of cscs in prostate cancer and focuses on the following topics: ( ) identification and characterization of prostate cscs; ( ) role that cscs play in tumor propagation and therapeutic resistance; ( ) role of metformin as a prostate csc sensitizer for conventional therapy. prostate structure and development the prostate is a glandular organ comprised of three distinct epithelial cell types. basal cells are found along the basement membrane of each prostatic duct and express ck , ck , cd , division of urology, department of surgery, sunnybrook health sciences centre, university of toronto, toronto, ontario, canada and institute of medical science, university of toronto, toronto, ontario, canada. correspondence: dr v venkateswaran, division of urology, department of surgery, sunnybrook health sciences centre, s- b, bayview avenue, toronto, ontario, canada m n m . e-mail: vasundara.venkateswaran@sunnybrook.ca received april ; revised june ; accepted june ; published online july prostate cancer and prostatic diseases ( ) , – © macmillan publishers limited all rights reserved - / www.nature.com/pcan http://dx.doi.org/ . /pcan. . mailto:vasundara.venkateswaran@sunnybrook.ca http://www.nature.com/pcan cd , p , bcl- and low or undetectable levels of androgen receptor (ar). , , , luminal cells form a layer above the basal cells and are the predominant cell type of the prostate. , luminal cells express high levels of ar, ck , ck , ck , cd and produce proteins such as psa and prostatic acid phosphatase (pap) that are secreted into the luminal space. , , , neuroendocrine cells are a rare population, which is dispersed among the basal layer, are androgen-independent, express chromogranin a and secrete neuroendocrine peptides. , , the primary survival of basal cells following androgen depriva- tion led to the hypothesis that prostate stem cells reside within the basal layer. , collins et al. identified a small population of basal prostate epithelial stem cells, which expressed high levels of α β . this was further corroborated by the identification of a small ( %) population of human prostate basal stem cells, which expressed cd and were restricted to the α β population. leong et al. demonstrated that a single stem cell with the lin-/ sca- +/cd +/cd +/cd + phenotype was able to regener- ate a prostate after transplantation in vivo. lineage tracing has shown that multipotent basal stem cells give rise to basal, luminal and neuroendocrine cells, as well as unipotent luminal progeni- tors, which cause the epithelial expansion observed during postnatal prostate development. wang et al. also demon- strated that basal cells and luminal cells undergo different types of division. basal cells can divide symmetrically to produce two daughter basal cells or asymmetrically to produce one basal cell and one luminal cell. however, luminal cells can only undergo symmetric divisions to produce two luminal cells and cannot produce any basal cells. these results lend support to the theory that there is a hierarchy of epithelial lineages containing both multipotent and unipotent stem cells in the developing prostate. role of cscs in prostate cancer cscs are defined as a subset of tumor cells that have the capacity to self-renew and generate the heterogeneous cell lineages that comprise a tumor. , the term ‘cancer stem cell’ was established for this unique subpopulation of tumor cells because they possess properties similar to those of normal tissue stem cells, such as self-renewal by symmetric or asymmetric division, high proliferative potential and the capacity to differentiate into multiple cell lineages. , , , the csc model postulates that cscs give rise to a hierarchically organized, heterogeneous tumor, with the cscs at the top of the hierarchy. the cscs then proliferate and generate pca progenitor cells, which despite only having limited self-renewal abilities, can differentiate into many different mature cells types, such as cd +ar+psa+ luminal secretory cells. the cscs themselves are typically quiescent, whereas the majority of the proliferating population of tumor progenitor cells are generated by the cscs. cscs are also thought to have an important role in cancer progression. colombel et al. demonstrated that primary prostate carcinomas contain a subset of cscs, which have a role in local invasion, specifically seminal vesicle invasion and bone metastasis. the percentage of cscs had a prognostic impact, particularly on the risk of progression of bone metastases. the percentage of cells expressing a stem cell phenotype in bone marrow metastases of prostate cancer patients has been shown to be predictive of bone metastases progression. there is also a small population of docetaxel-resistant cells, likely cscs, that have been shown to be higher in metastasic compared to primary patient samples, and, in primary untreated samples, the percentage of these cells was associated with prognostic factors and time to biochemical relapse. the role of prostate cscs in recurrence and development of crpc is likely due to their intrinsic therapeutic resistance. conventional anticancer therapies such as radiation, androgen deprivation and chemotherapy target the rapidly proliferating bulk of tumor cells, but they may not affect the small quiescent, androgen-independent csc population. this reservoir of cscs could then in the future, after therapy has been halted, begin proliferating again and give rise to another tumor, which would have survived selective pressure from therapy. the selection theory of androgen resistance postulates that there is a set of pre-existing adt-resistant cancer cells in tumors. androgen depletion, therefore, provides selective pressure, killing the androgen-dependent cancer cells while androgen-independent tumor cells survive and can then give rise to castration-resistant tumors. prostate cscs are candidates for these pre-existing adt-resistant cells that could give rise to crpc since they have self-renewal and tumor-propagating capabilities, as well as a lack of or very low ar expression. recurrent pca tissue samples are enriched in cscs, which are likely responsible for chemoresistance. an important distinction should be made between cscs and the cancer cell of origin. the cell of origin refers to the initial cell that is the target of genetic alteration(s) that result in malignant transformation. , cscs, in contrast, are tumor-propagating cells that sustain malignant growth. cscs may arise from a number of different types of cells including normal stem cells, restricted progenitors or differentiated cells. , , identification and characterization of prostate cscs cscs can only be identified and characterized experimentally. the gold standard for defining cscs functionally is serial transplantation in immunodeficient mice. this approach confirms the properties of self-renewal and tumor propagation. , many csc studies have used experimental methods that were established for enriching normal stem cells including transplanta- tion of flow cytometry-sorted cscs, side-population and alde- fluor assays, and lineage-tracing studies. a number of different populations of prostate cscs have been identified. a population of cd +/α β high/cd + cancer stem cells from human prostate tumor samples has been identified in human prostate tumor tissue. , the cd +/α β high population was also shown to be enriched in cscs in lapc- cells. populations of cd + prostate cancer stem cells have been shown to be more proliferative, tumorigenic and metastatic than cd − prostate cancer cells, which are all typical characteristics of cscs. , aldehyde dehydrogenase (aldh) has also been shown to be a marker for prostate cscs. aldh+ prostate cancer cells have been shown to exhibit several csc characteristics and is considered a marker for prostate cscs. , aldh+ prostate cancer cells have been shown to possess enhanced clonogenicity, migration, tumorigenicity and readily form metastases in vivo. qin et al. also identified highly tumorigenic castration-resistant psa− /lo cscs, which can be further enriched to include a population of aldh+/cd +/α β + cells. atp-binding cassette (abc) transporter abcg + prostate cscs have also been isolated using the side-population method, which allows for the isolation of cells that can efflux hoechst dye more efficiently because of elevated abc transporter expression. , stemness markers have also been used to characterize csc populations in the prostate. overexpression of nanog in lncap and du human prostate cancer cell lines promoted csc properties and enhanced the expression of cd , cd , aldh a and abcg . prostate cscs have also been shown to express oct and sox along with nanog. , guzel et al. also showed an increased expression of sox , oct , nanog, and abcg in recurrent prostate cancer tissue samples, indicating an enrichment in prostate cscs. a number of other cell surface markers identify prostate cscs. these are included in table . metformin and prostate cancer stem cells mj mayer et al prostate cancer and prostatic diseases ( ), – © macmillan publishers limited prostate cscs and therapeutic resistance prostate cscs are resistant to most conventional cancer therapies. although there is some evidence that cscs are radioresistant in breast cancer and glioblastoma cell lines, this has not yet been demonstrated in prostate cancer. – prostate cscs are thought to contribute to the development of crpc. seiler et al. demonstrated that adt resulted in castration resistance and overexpression of stemness markers such as sox and oct , indicating a role for prostate cscs in adt resistance. in vivo studies have demonstrated enhanced expression of stem cell markers in resistant tumors in castrated mice. the peak expression of these markers also occurred soon after adt, suggesting that prostate cscs may have a role as an adaptive survival mechanism. cscs may confer resistance to chemotherapy. one contribut- ing factor to this chemoresistance is the expression of abc transporters. abc transporters are membrane bound and can pump various small molecules, such as cytotoxic drugs and dyes, out of cells at the expense of atp hydrolysis. cscs express high levels of abc transporters. these pump chemotherapeutic drugs out of the cytoplasm, resulting in reduced intracellular drug concentrations. , zhang et al. demonstrated that tumor- spheres from pca cell lines expressing high levels of cd and abcg were chemoresistant, likely due to the elevated expression of abcg . a subset of cells with high tumor-initiating capacity, likely cscs, have been identified in both du and rv human prostate cancer cells, as well as in human pca samples. these cells contribute to docetaxel resistance and tumor re-initiation. metformin and prostate cancer metformin, a commonly prescribed and well-tolerated oral biguanide used to treat type diabetes, has been shown to exert anti-neoplastic effects in several types of cancer. metformin reduces hepatic gluconeogenesis, increases glucose uptake in peripheral tissue such as skeletal muscle and increases insulin sensitivity. , evans et al. showed a reduced cancer burden in diabetic patients treated with metformin compared with those treated with other diabetic therapies. since that initial paper, metformin has been shown to have anti-neoplastic properties in breast cancer, , ovarian cancer, pancreatic cancer and prostate cancer. in prostate cancer, metformin inhibits the proliferation of lncap, du and pc human prostate cancer cell lines and also reduced tumor growth in lncap xenografts. in prostate cancer patients, metformin use is associated with a decreased risk of pca diagnosis while other oral diabetes medications are not. increased cumulative metformin exposure after pca diagnosis has been associated with decreased all-cause and pca-specific mortality in diabetic patients. a meta-analysis by yu et al. showed that metformin was associated with a significant reduction in cancer risk and biochemical recurrence. metformin targets cscs in breast cancer, metformin effectively targets breast cscs and enhances the effectiveness of some therapies. song et al. demonstrated that metformin was cytotoxic to radioresistant breast cscs and increased the efficacy of radiation in suppressing tumor growth in vivo, likely by reducing the population of cscs. hirsch et al. also showed that metformin targeted breast cscs in four cell lines, enhanced the tumor-suppressing effect of doxorubicin and prolonged remission in vivo. furthermore, metformin combined with a fourfold lower dose of doxorubicin was shown to be as effective as the standard dose of doxorubicin treatment alone in vivo. metformin has also been shown to enhance the effect of paclitaxel and carboplatin by targeting cscs in breast cancer xenografts at doses comparable to the dose per kg used in type diabetes patients. in pancreatic cancer, metformin has been shown to significantly decrease cell survival, clonogenicity, wound-healing and sphere-forming capacity in pancreatic cscs and also decreased the expression of csc markers such as cd , cd , aldh , nanog and oct . , – in glio- blastoma cell lines, metformin effectively reduced the proliferation of cd + cscs in an akt-dependent manner. the cd + population of colon cancer cscs have been shown to be signi- ficantly reduced by treatment with metformin and it enhanced the antiproliferative effect of -fluorouracil on colon cscs. in addition, metformin acts synergistically with -fluorouracil and oxaliplatin to inhibit cell proliferation and tumor growth of chemoresistant colorectal cancer cells by reducing the viability of colorectal cscs. mechanism of action of metformin in cscs biguanides, such as metformin, exert their effects by decreasing oxidative phosphorylation which induces energetic stress. this leads to a number of secondary cell lineage-specific effects. metformin action is mediated through direct effects on the table . markers for isolation of prostate cscs marker expression level characteristics reference aldh high enzyme oxidizes aldehydes li et al., qin et al., finones et al. abcg high atpase transporter foster et al., gangavaparu et al. cd + cell adhesion and signaling patrawala et al., patrawala et al., collins et al., hurt et al. cd (prominin- ) + marker normal stem cells and cscs richardson et al., collins et al. c-kit (cd ) + receptor tyrosine kinase finones et al. integrin α β (cd b) high collagen receptor collins et al., patrawala et al., guzman-ramirez et al. cd f high laminin binding guzman-ramirez et al. cd + cell adhesion jiao et al. psa − /lo glycoprotein qin et al. ck / + cytokeratin tokar et al. ck / + cytokeratin tokar et al. nestin + intermediate filament protein guzman-ramirez et al. sca- + cell surface marker lawson et al., xin et al. smo (smoothened) + g-protein-coupled receptor patrawala et al. sox + transcription factor (self-renewal) rybak and tang oct + transcription factor (self-renewal) patrawala et al. nanog + transcription factor (self-renewal) jeter et al. abbreviation: aldh, aldehyde dehydrogenase; csc, cancer stem cell. metformin and prostate cancer stem cells mj mayer et al © macmillan publishers limited prostate cancer and prostatic diseases ( ), – mitochondria, either by inhibiting mitochondrial complex or the redox shuttle enzyme mitochondrial glycerophosphate dehydro- genase. , – this causes inhibition of oxidative phosphorylation and reduced atp production and oxygen consumption. the decline in mitochondrial atp production triggers activation of the cellular energy regulator amp-activated protein kinase (ampk) thereby directing cells towards an antiproliferative ‘energy-saving’ phenotype characterized by the downregulation of atp-consuming processes such as protein and fatty acid synthesis. , the antiproliferative effect of this metabolic reprogramming by ampk was thought to contribute to the anti- neoplastic effect of metformin. however, the activation of ampk can enhance cell survival under the conditions of energetic stress and could in fact have a pro-survival effect. the effect of metformin in pca cells has been shown to be independent of the ampk pathway. tumors with loss of lkb , an upstream kinase required for ampk activation, are hypersensitive to biguanides, which indicates that cancer cells deficient in ampk will be less likely to reduce energy consumption due to biguanide-induced reduction in atp production and would increase the likelihood of these cells experiencing an energy crisis. more research is still needed to elucidate the antiproliferative and pro-survival effect of ampk in cancer cells and the specific downstream effects of metformin-mediated inhibition of mitochondrial oxidative phosphorylation. this mechanism of action of metformin has been evaluated in cancer. in human breast cancer cells, metformin directly inhibits mitochondrial complex and citric acid cycle function, which reduces mitochondrial respiration. reduced mitochondrial oxidative phosphorylation results in impaired mitochondrial atp production and forces cancer cells to compensate by increasing aerobic glycolysis. therefore, cells which rely more heavily on mitochondrial oxidative phosphorylation are more sensitive to metformin treatment and cscs are included in this category. pancreatic cancer stem cells have been reported to have a highly mitochondrial-dependent metabolic profile. this is quite differ- ent from the majority of cancer cells that proliferate uncontrollably and limit their metabolism primarily to glycolysis even in the presence of oxygen (i.e., aerobic glycolysis), known as the warburg effect. cscs do not rapidly divide and therefore do not undergo this metabolic shift. if cscs continue to rely on mitochondrial atp production, they would be more sensitive to metformin treatment and would not be able to compensate effectively by switching to aerobic glycolysis. there are two possible scenarios related to the role of ampk as the expression of ampk in cscs has not been fully elucidated. if cscs do have functional ampk, the activation of ampk would likely prevent cscs from shifting to aerobic glycolysis, which would cause an energy crisis and render cscs incapable of compensation. if the cscs are deficient in ampk, they would have an innate inability to compensate for an energy crisis and ampk-deficient cscs would, therefore, be more sensitive to metformin treatment. both scenarios would ultimately result in making cscs more sensitive to additional stressors after metformin treatment, suggesting that metformin could be used as a csc sensitizer for various types of cancer therapy (figure ). the pharmacokinetics of metformin also play an important role in its mechanism of action as different tissues have varying levels of exposure to biguanides, such as metformin. this is due to the fact that metformin requires membrane transport proteins such as organic cation transporter (oct ) to enter cells. the varying expression level of transport proteins between cell types can affect the bioavailability of metformin. for example, hepatocytes express high levels of oct , which allows for enhanced cellular uptake of metformin and the accumulation of relatively high metformin concentrations in the liver. once metformin has entered a cell, the mitochondrial membrane potential causes an increased uptake of metformin into the organelle and results in the mitochondria being the site of the highest concentration of the drug within a cell. the accumulation of metformin in the mitochondria may contribute to its ability to effectively inhibit oxidative phosphorylation and cause an energy crisis in cscs. it is also possible that if cscs have a higher oct expression level, the effect of metformin on these cells would be enhanced. however, the oct expression levels of cscs have not been elucidated. role of metformin in prostate cancer therapy a few studies suggest that metformin may enhance the effectiveness of prostate cancer therapies. metformin has been shown to enhance the effectiveness of adt. research conducted in our laboratory has shown that metformin combined with bicalutamide significantly reduces prostate cancer cell growth more effectively than either metformin or bicalutamide alone. in addition, the combined treatment affected ar-positive lncap cells by altering cell proliferation, whereas combined treatment in figure . mechanism of action of metformin in prostate cancer stem cells. adt, androgen-deprivation therapy. oct, organic cation transporter. metformin and prostate cancer stem cells mj mayer et al prostate cancer and prostatic diseases ( ), – © macmillan publishers limited ar-negative pc cells promoted apoptosis. nguyen et al. also showed that combined treatment of enzalutamide and metformin significantly reduced tumor size in enzalutamide-resistant lncap c - b xenografts, and combined treatment was more effective than enzalutamide or metformin alone. iliopoulos et al. demonstrated that metformin combined with doxorubicin sup- pressed tumor growth in pc xenografts. radiosensitization by targeting prostate cscs is another potential benefit. reducing oxygen consumption may have an impact on prostate cscs as reducing oxygen supply would impair mitochondrial oxidative phosphorylation. this would result in cscs compensating by using glycolysis, which would cause a cellular energy crisis that would make cscs more sensitive to additional stressors such as radiation. in one study, prostate cancer patients taking metformin during radiotherapy had a significant reduction in early biochemical relapse. when considering future clinical trials, an important considera- tion is the potential benefit of conducting trials assessing the effect of metformin on prostate cscs. currently two trials are registered on clinicaltrials.gov assessing the effect of metformin combined with anticancer therapies for prostate cancer. taxomet is a phase ii trial recruiting patients to assess the effect of metformin combined with taxotere (generic name of docetaxel) on psa response rate, biochemical and clinical progression-free survival, overall survival and tolerance. the metab-pro trial is a phase ii pilot study assessing the impact of combining metformin with abiraterone treatment on survival in patients with metastatic crpc. this is indicative of the definite interest in the use of metformin as a sensitizing agent for anticancer therapies. however, there is no focus on prostate cscs in either of the trials mentioned above. currently, very few trials are registered that assess the effect of metformin on cscs. a randomized clinical trial on colon cancer patients currently in the data analysis phase assessed the effect of metformin administered before surgery on the proportion of cscs identified in tumors. there is also a phase ii trial currently recruiting ovarian, primary peritoneal and fallopian tube cancer patients to assess whether metformin combined with chemotherapy will prevent relapse by targeting cscs. however, again there are no trials exploring the effect of metformin on prostate cscs. if metformin does, in fact, have a csc-specific effect when combined with other anticancer therapies, this would provide evidence for a novel therapeutic approach for prostate cancer that would warrant assessment in clinical trials. conclusion great strides have been made in establishing expression profiles for prostate csc isolation and characterization. therapeutic resistance continues to be a problem in the treatment of prostate cancer, and prostate cscs are likely an important factor in treatment resistance, cancer recurrence and progression. the ability to selectively eliminate prostate cscs holds therapeutic promise. metformin has been shown to target cscs in a number of different solid tumors although there is limited data in prostate cancer. establishing the effect of metformin as a potential sensitizer for prostate cscs and combining metformin with other anticancer therapies to enhance their effectiveness provides an opportunity to develop improved therapeutic options for prostate cancer patients. conflict of interest the authors declare no conflict of interest. references abate-shen c, shen mm. molecular genetics of prostate cancer. genes dev ; : – . maitland nj, collins at. prostate cancer stem cells: a new target for therapy. j clin oncol ; : – . feldman bj, feldman d. the development of androgen-independent prostate cancer. nat rev cancer ; : – . li h, tang dg. prostate cancer stem cells and their potential roles in metastasis. j surg oncol ; : – . heidenreich a, bastian pj, bellmunt j, 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stem/progenitor and cancer initiating cells. plos one ; : e . tokar ej, ancrile bb, cunha gr, webber mm. stem/progenitor and intermediate cell types and the origin of human prostate cancer. differentiation ; : – . lawson da, xin l, lukacs r, xu q, cheng d, witte on. prostate stem cells and prostate cancer. cold spring harb symp quant biol ; : – . xin l, lawson da, witte on. the sca- cell surface marker enriches for a prostate- regenerating cell subpopulation that can initiate prostate tumorigenesis. proc natl acad sci usa ; : – . metformin and prostate cancer stem cells mj mayer et al © macmillan publishers limited prostate cancer and prostatic diseases ( ), – 	metformin and prostate cancer stem cells: a novel therapeutic target 	introduction 	prostate structure and development 	role of cscs in prostate cancer 	identification and characterization of prostate cscs 	prostate cscs and therapeutic resistance 	metformin and prostate cancer 	metformin targets cscs 	mechanism of action of metformin in cscs 	role of metformin in prostate cancer therapy 	conclusion 	references science american association for the advancement of science science serves its readers as a forum for the presentation and discussion of important issues related to the advance- ment of science, including the presentation of minority or con- flicting points of view, rather than by publishing only material on which a consensus has been reached. accordingly, all ar- ticles published in science-including editorials, news and comment, and book reviews-are signed and reflect the indi- vidual views of the authors and not official points of view adopted by the aaas or the institutions with which the au- thors are affiliated. publisher: richard s. nicholson editor: daniel e. koshland, jr. news editor: ellis rubinstein managing editor: patricia a. morgan deputy editors: philip h. abelson (engineering and applied sciences); john . brauman (physical sciences) editorial staff assistant managing editor: monica 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( - - ); u.k., europe: nick jones, + ( ) ; telex ; fax ( ) . information for contributors appears on page xl of the june issue. editorial correspondence, including requests for permission to reprint and reprint orders, should be sent to h street, nw, washington, dc . tele- phone: - - . advertising correspondence should be sent to tenth floor, broadway, new york, ny . telephone - - or wu telex scherago, or fax - - . august i volume number solar power and priorities a short while ago science published a cartoon of a desert scene with a lone billboard proclaiming, "invest now! greenhouse estates coming soon: the best in ocean front living!" it would indeed be ironic if the cartoonists and the real estate agents were more thoughtful planners than the governments of the world. as serious as the problems of acid rain, toxic waste, and depletion of the ozone layer are, the greenhouse effect looms over all of them because it poses such great potential damage to the environment and is by far the most difficult to solve (see "issues in atmospheric science," science, february ). the consensus prediction for a doubling of the co concentration, for example, is the year -extremely close for a solution requiring scientific innovation, political courage, and international cooperation. in developed countries the standard of living has been correlated with energy consumption per capita, with a steady rise in consumption occurring in the countries already consuming the most energy. in developing countries the consumption of energy is much lower, but the rate of increase is high. that mixture is explosive because developed countries argue that there is no point in conserving energy if developing countries keep using up the margin, whereas developing countries argue that they deserve to reach the consumption level of their rich peers. one might argue that we should delay action until the data on the current global warming are conclusive were it not for the fact that the energy industry is so massive. even after a course of action is agreed upon, years will be required to implement it. damaging environmental effects may be irreversible by then. a further argument against delay is that the remedies for the energy problem will help solve other environmental and economic problems. the first and most important decision is the inauguration of a massive effort to use solar power. solar power is not now cost-effective compared to oil. when the temporary energy crisis in and was over, the pressure for immediate alternative sources of energy disappeared. the long-range problems were forgotten. to develop solar energy technology to supply large amounts of power (not just for satellites and specialized missions, important as they are) should be a major priority of our civilization. it will be more and more cost- effective as oil becomes more and more expensive. the energy crisis requires both technological fixes, such as solar energy, and societal restraint fixes, such as limits on the sizes and number of automobiles. the list of actions could go on to include major conservation efforts, better urban planning, encouragement of mass transit, tax laws to save our high-rise central cities, and zoning to decrease urban sprawl. if those measures, which will take much political courage, are to have a chance, they must be accompanied by some tough dealing on international issues. the developed countries can hardly say to the developing ones that the globe is at its limit of producing greenhouse gases and newcomers must stick to using bicycles. the developing countries, on the other hand, can hardly tell the developed countries that they must subsidize the continuing population explosion. some international trade-offs can obviously take place: developed countries can concentrate on conservation plans and the funding for technologi- cal solutions; 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hebei engineering university, handan, , hebei, china abstract: currently, low-carbon lifestyle has come to the fore, and is valued by the countries around the world. accord- ingly, low-carbon tourism has become the goal of development. it is a long way to go, but we have aimed high in the on- going exploration. this paper is to provide a reference for the construction of low-carbon tourism. it is unfolded with the definition and importance of low-carbon tourism, followed by basic evaluation system of low-carbon tourism and specific suggestions for its implementation. keywords: evaluation system, implementation strategy, low carbon tourism. . introduction under the aggregation of world energy crisis, low-carbon lifestyle has been valued all over the world. in the specific suggestions of tourism development proposed by the state council in , it is mentioned that the course for the future of tourism industry is low-carbon tourism [ - ], which re- quires joint efforts from the government, tourism sector, and faculty of research, so that tourism can develop in an effi- cient, energy saving, and eco-friendly way. . basic theory of low-carbon tourism . . definition of low-carbon tourism the so called low-carbon tourism as the name suggests is to reduce “carbon” emissions during travel. the “carbon” here means green house gases, carbon dioxide mainly. in other words, it should be green travel [ - ], with light energy consumption, little pollution, and few carbon dioxide emis- sions. low-carbon tourism is designed with low-carbon itin- eraries, equipped with eco-friendly outfit, and required low transport emissions. . . connotation of low-carbon tourism . . . content of low-carbon tourism low-carbon tourism is an extension of low-carbon econ- omy. it is in the framework of low-carbon economy. sup- ported by low-carbon technology and low-carbon mecha- nism, low-carbon tourism aims at reducing the carbon diox- ide emission and the consumption of energy during travel [ , ], so that both the needs of wonderful traveling experience and sustainable development of economy and environment can be met. . . . the meaning of low-carbon tourism essentially low-carbon tourism is an extension of eco- tourism. it requires low-carbon production and operation in the tourism. for example, with the help of new technology and new energy sources, hotels, restaurants, scenic spots and transportation reduce water, electricity, and other energy consumption as well as the waste, and ultimately to achieve reduction of greenhouse gas emissions such as carbon diox- ide, so that tourism industry and tourism economy can de- velop along with a sustainable environment. the main re- quirements of low-carbon tourism are low carbon transporta- tion, low-carbon consumption, low-carbon accommodation and less travel footprints, etc. . . significance of low-carbon tourism china now faces serious environmental pollution, mainly marked by smog. when tourists are enjoying the scenery in a trip, they should think about whether their activities destroy the land, river, plants, and ecosystem. here we introduce the significance of low-carbon tourism. the two significance of low-carbon tourism are respectively for individual and soci- ety. for individual, modern lifestyle casts great pressure on individuals. low-carbon tourism is a relaxing travel mode close to nature. tourists are free from their daily worries and stresses, for example, by walking instead of taking a ride, tourists can enjoy the missing scenery in cars or buses. for society as a whole, low-carbon and environmental protection are urgent. today, air pollution, energy crisis and other is- sues cannot be resolved merely through technology and sci- ence, but joint efforts from all mankind. developing low- carbon lifestyle, however, is the most efficient way to solve the environmental problems brought by economic growth. tourism is closely related to natural resources, thus it is ur- gent to make it low-carbon. china is gradually confirmed as one of the world’s great powers, it needs to make an example of a large country in the field of environmental protection. thus the implementation of low-carbon tourism is a neces- sary measure. . . challenges in implementing low-carbon tourism . . . terrible waste of resources chinese tourism industry is facing appalling waste in its widely existed extensive operation and management. for the open cybernetics & systemics journal, , volume yingfa yang example, energy saving materials are uncommon in the con- struction of scenic facilities; some construction area is too large; the problem of construction material waste is serious; tourists use times of natural resources than the residents, such as water, electricity, oil and gas; consumable stuff is widely used, for example, disposable toothbrush, slippers, bowl and chopsticks and other items, which causes huge waste and pollution. . . . lack of environmental protection awareness according to the survey, chinese tourists are lack of en- vironmental protection awareness and actions mainly in three aspects: food, shelter, and transportation. first of all, when tourists purchasing the specialty or special food, they always select those with delicate packages, which increases the emissions in packaging, storage, and transporting. in addition, because of face and vanity, tourists choose large luxurious restaurants and causes great waste. secondly, tour- ists often use disposable supplies provided by the hotel, re- sulting in waste. finally, people travel with fast and conven- ient transportation such as airplane. in addition, with the increase in private car ownership, driving becomes one of the main means of traveling. while people are enjoying the convenience of transportation, they are placing the environ- ment at heavy greenhouse gas emission. . . . damage to the environment of tourism resources exploitation in developing tourism economy, exploiting tourism re- sources plays an important role. however, the course of ex- ploiting tourism resources in the pursuit of economic growth also damages environment. many scenic interests have ex- plored and exploited natural resources without cautious in- spection, demonstration and scientific planning, but simply pursued economic growth. such activity sacrifices natural resources, and damages local ecology and environment. . evaluate the basic model of low- carbon travel . . basic principles of the system construction . . . comprehensive representation principle the standard in the table is an organic whole. it compre- hensively reflects economic results from low-carbon tour- ism. from each different perspective, there are different in- dicators of low-carbon tourism. and only in this way, this model makes sense. what’s more, each indicator in the model are mutually independent and representative. . . . principle of combining qualitative and quantitative evaluation the indicators must be selected in the combination of qualitative and quantitative evaluation, so that they are valid and practical. quantitative principle ensures the evaluation objective and reasonable, while qualitative principle solves problems that are wide-range and cannot be quantified. . . . dynamic stability principle developing low-carbon tourism is a dynamic process. firstly, in the evaluation process, dynamics such as the eco- nomic, technological, and social changes of the indicators must be paid attention. secondly, the dynamics of the index should be strengthened. in addition, the evaluation system should be relatively stable. this will not only reflect the cur- rent situation of eco-tourism but also reflect the perspective of future development. . . . principle of scientific use the selection of qualitative changes is based on reality, for example, the power of eco-tourism, status, and screen- ings and other negative understanding and analysis. the in- dicators should meet the development objective and re- quirements of eco-tourism, and be reflected in the real eco- nomic development, environment protection and legislation. . . . principle of operation in the evaluation system of low-carbon tourism system, we try to use existing data. despite the inadequate system and indicators of low-carbon tourism, there are still statistics that can be used, and we can rule out those that can’t be quantified. . . . principle of system level low-carbon tourism is a complex systemic issue, whose evaluation system needs to reflect all aspects of the design as well as the characteristics. the system can be divided into macro and micro according to the function. . . indicator framework indicator system is divided into four layers in the follow- ing chart: the overall goal, the criteria layer, sub-criteria layer, and the index layer table . . . index weight . . . matrix the first step of analyzing the system is to determine the importance of each layer. plus qk and the dominance relation with the index in the layer, we can introduce the following matrix, table , to compare which indicator is more impor- tant, in which rj> . now we need to judge if the standard of quality in the matrix is consistent with its result. if it is, we take it a consis- tent matrix. because of its complexity of the issue, there are many factors to influence the result, which requires us to use matrix as auxiliary. the r-rated pairwise comparison of each factor can be drawn judgment in the matrix, it is solved as following formula. . . . testing the consistency of the matrix we can use root method to calculate the maximum in matrix and eigenvectors and normalize them. to calculate the consistency of all levels of arrangement, we can use the following formula: ri ci cr = ( ) ci represents a hierarchy consistency, cij represents the consistency of sub-criteria layer and the corresponding implementation strategies of low-carbon tourism the open cybernetics & systemics journal, , volume table . index in indicator system at all level. overall goal criteria sub-criteria index proportion in gdp/s comprehensive economic efficiency/r revenue growth/s number of r level scenic spots/s value of tourism resources/r resource abundance/s proportion of funds in low-carbon technologies/s driving force/q technological advances/r ratio of ecological building/s number of eco-friendly restaurant/s number of green travel tourists/s infrastructure /r number of buses/s proportion of non-fossil energy sources/s energy consumption per unit/s per capita carbon dioxide emissions/s per capita footprint/s rise of carbon dioxide emissions/s energy emissions/r emissions from star hotel/s forest coverage/s urban greening/s amount of municipal solid waste/s sewage treatment capacity/s ecological indicators/q environment /r air pollution treatment capacity/s eco tourism itinerary/s destination /r environmental compliance rate/s tourism development plan/s evaluation system/s administrative department/r legislation/s public awareness rate/s degree of development of low-carbon tourism(p) corresponding indica- tors/q tourists /r public support rate/s table . qk matrix. qk r r … rn r r … r n r r r … r n … … rn r r … rnn the open cybernetics & systemics journal, , volume yingfa yang fig. ( ). cr value table. criteria layer,ri represents random consistency, rij repre- sents the consistency of sub-criteria layer and the corre- sponding criteria layer in matrix,cr represents the matrix consistency. cr values of matrix is shown in fig. ( ). when cr< . , the consistency is regarded to meet the requirement of consistency, otherwise, it does not meet the requirement. according to calculations, the low-carbon tour- ism matrix meet the requirements of consistency. . . . establishing a low-carbon eco- tourism evaluation model the index of low-carbon eco-tourism are of two types, forward index and reverse index, calculated as. forward index: ii= (actual index value pi/ reference value ti) x ( ) reverse index: ii = (reference value ti/ actual index value pi) x % ( ) the ecology gathers each individual index in the system and undertakes a comprehensive evaluation. through a weighting function, it is calculated as = = n i jjj wria )( ( ) . main measures to implement low- carbon tourism . . strengthening the mechanism the government and department of tourism strengthen the role of guiding the tourism industry by establishing ap- propriate systems and build a low-carbon travel system as well as oversight mechanism as auxiliary, for example, manufacturing tourism products, designing itinerary, pro- moting the significance of low-carbon tourism, and introduce rules and laws. on one hand, the administrative departments should strengthen the low-carbon assessment of the attrac- tions, hotels, restaurants and transportation. with appropriate assessment indicators and restrictions of the energy utiliza- tion and emission, the institutes and programs with high- volume emission, heavy pollution, and serious waste will gradually be phased out. on the other hand, incentive mechanism should also be established, to encourage the ap- plication of eco-friendly equipment in institutions and other environmental protection behaviors. in addition, government should increase the financial subsidies for low-carbon tour- ism, and introduces conducive tax policy for low-carbon tourism. the united states, for example, is attaching great importance to low-carbon tourism, and have introduced a set of laws and regulations to guide the tourism industry and results have been achieved. . . strengthening plans for low-carbon tourism low-carbon tourism should be placed into the criterion of tourism development, with indicators of carbon dioxide emissions, waste disposal capacity, public transport. when rating hotels and scenic spots, carbon emission should also be one of the criterion. the scenic spot planning must be technically innovative, for example, establishing the evalua- tion system of “low-carbon scenic spot”, and supervising the transport, accommodation, entertainment, manufacture, and distribution sectors. it can be given visual logo of to repre- sent their carbon degree, and the logo should include num- bers, graphics, and color, so as to complete the digital net- work system. . . promoting publication of the low-carbon tourists are the principle part of a trip. take effective measures in a trip is the key to implement low-carbon tour- ism. with social development, the requirements of environ- mental protection become increasingly strict, and yet peo- ple’s awareness does not meet the strict requirements. thus we should promote publication of the low-carbon awareness. the tourism department is required to take various forms to promote publication deepening into the community, so that residents will raise the awareness of environmental protec- tion, and abandoning the extravagant attitude as well as life- style. in the meantime, tourists abandon the behaviors of damaging environment, for example, it is advocated to choose transport with less carbon dioxide emission such as walking, bicycle, bus and train, and lodging into hotels with green logo. japan performs best in this aspect. the govern- ment and social groups regularly advocate in tv, internet and newspaper, so that people are highly aware of low- carbon and eco-friendly tourism and environmental protec- tion as well. conclusion with increasingly environmental damage brought by growing economy, many cities in china are facing serious environmental pollution such as heavy smog. thus, low- carbon environment has become a pressing issue. tourism as a closely related industry to natural resources, the implemen- tation of low-carbon tourism is essential for the protection of environmental resources. this paper have described the defi- nition of low-carbon tourism, low-carbon tourism evaluation system, as well as collective measures to implement low- carbon tourism, that is, to strengthen mechanism and plan of low-carbon tourism, and to promote publication of low- carbon awareness. this study hopes to provide a valuable reference to relevant institutions and staff. conflict of interest the author confirms that this article content has no con- flict of interest. implementation strategies of low-carbon tourism the open cybernetics & systemics journal, , volume acknowledgements this work is supported by hebei province social science fund "introverted perspective to the path of chinese culture promoted the hebei cultural soft power" achievements (no. hb zx ). references [ ] w. yang, "the development of tourism in the low carbon econ- omy," international business research, vol. , no. , pp. , . 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[ ] k. f. wee, "energy consumption and carbon dioxide emission considerations in the urban planning process in malaysia," pp. - , . received: june , revised: july , accepted: august , © yingfa yang; licensee bentham open. this is an open access article licensed under the terms of the (https://creativecommons.org/licenses/by/ . /legalcode), which permits unrestricted, non- commercial use, distribution and reproduction in any medium, provided the work is properly cited. influence of absorptance in the building envelope of affordable housing in warm dry climates energy procedia ( ) – available online at www.sciencedirect.com sciencedirect - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). selection and/or peer-review under responsibility of ises. doi: . /j.egypro. . . ises solar world congress influence of absorptance in the building envelope of affordable housing in warm dry climates maría g. alpuchea*, ileana gonzáleza, josé m. ochoaa, irene marincica, alejandro duartea, esaiy valdenebroa adepartment of architecture and design, university of sonora, blvd. luis encinas and rosales, hermosillo, sonora, mexico. abstract in mexico, as in many other countries, the energy crisis has permeated throughout many sectors, particularly the construction sector. mexico has started to develop and implement actions for the efficient use of energy in order to reduce its consumption. the field of building construction has been particularly active in studying ways to optimize the use of energy, especially regarding energy use indoors. one of the main goals of architectural design is to create the proper indoor conditions so individuals can carry out their daily activities in a comfortable area. interior space must be designed and calculated to provide a comfortable temperature, appropriate lighting, sound control and ventilation for individuals to carry out their daily activities, but must also address the energy required to provide all these characteristics. in warm dry climates, air-conditioning is responsible for a significant amount of the energy consumed in buildings. proper building design is necessary in order to reduce energy consumption in this sector. this paper shows the results of simulations with the energy plus software to compare the thermal performance of a low-cost housing located in a warm dry climate, hermosillo, sonora, with similar construction systems in the envelope. furthermore, an analysis of the effect of the color exterior finish, represented as a gradual change in the absorptance to solar radiation. the simulation is performed for two conditions of use of low-cost housing, the first condition considers the room without air conditioning and the second considers the air conditioned room. to simulate analyzed housing with air conditioning, is used an air conditioner from the database energy plus, corresponding to a mini-split system compact unit zone cooling with a cop (coefficient of performance) of . . © the authors. published by elsevier ltd. selection and/or peer-review under responsibility of ises keywords: thermal performance, low-cost housing, energy efficiency, warm dry climate, energy plus. * corresponding author. tel.: + - - ; fax: + - - . e-mail address: mgalpuche@arq.uson.mx © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). selection and/or peer-review under responsibility of ises. http://crossmark.crossref.org/dialog/?doi= . /j.egypro. . . &domain=pdf maría g. alpuche et al. / energy procedia ( ) – . introduction according to the national balance of energy of [ ], the consumption of electricity in the residential and commercial buildings represents . % of the total consumption of electricity in mexico, and an important amount of this percentage corresponds to the energy used by mechanical systems for indoor air conditioning. poor architectural design that does not take into account the diverse climates of the country’s different regions has made the use of mechanical systems for air conditioning more common and necessary. the consumption of residential electricity has been continuously increasing in the last decades. it is until recently that, in the face of a global energy crisis, a few governmental agencies have started to look for ways to reduce energy consumption and to change regulations to promote energy efficiency in buildings. research on thermal behavior and energy consumption in buildings has become more prevalent in the last decade, due in part to the development of better and more complete simulation programs. the increased interest in this area has promoted a greater diversity in the scope of studies, from the overall evaluation of buildings to the specific analysis of the elements that have an effect on how interior spaces gain or lose heat. the warming or cooling loads in a building depend on many variables like geographic location and climate characteristics, the construction system of the building envelope, the number of occupants, the types of activities that take place in the interior space, and the operation and maintenance of the building. the thermal behavior of the building envelope is primarily affected by solar radiation, which is responsible for the majority of the heat gain in buildings. in regions with clear skies and warm climates, solar radiation can reach up to , w/m . in these regions, solar radiation is the key factor to consider when designing for indoor comfort. a poorly designed building that does not take into account the effects of solar radiation will have higher heat gains and consequently, will require the continuous use of air conditioning systems in order to ensure the comfort of indoor spaces. as a result, this building will have a higher consumption of electricity, especially during the warm season. in , shariah et. al. [ ] evaluated the influence on cooling and warming loads while using different construction systems and different absorptance coefficients on the exterior surfaces of buildings envelopes in jordan. in addition, berdahl and bretz, [ ]; suehrcke et. al., [ ]; yao and yan, [ ] among others, have analyzed the relevance of using materials that reflect the solar radiation on the outer surface of the roof in order to significantly reduce thermal cooling loads. also, in , ma et. al., [ ] analyzed the important effect that low solar absorptance and high emittance materials have over cooling loads in hot climates; whereas high solar absorptance and low emittance materials have a significant effect on heating loads in cold climates. libbra et. al., [ ] conclude, in agreement with other authors, that any decrease in average solar reflectance of urban surfaces causes a decrease of peaks in air temperature during the summer. furthermore, the urban heat island effect is mainly the consequence of increased building density within cities, and the use of materials with inadequate optical and thermal properties. various heat island effect mitigation strategies have been developed, and their effectiveness has been verified in several applications, as shown by santamouris et. al., [ ]; synnefa et. al., [ ]; zinzi et. al., [ ]; takebayashi et. al., [ ]. this paper shows results of simulations carried out with the energy plus software to compare the thermal performance of a low-cost housing located in a warm dry climate, hermosillo, sonora, with same construction systems in the envelope. furthermore, an analysis of the effect of the color exterior finish, represented as a gradual change in the absorptances to solar radiation. maría g. alpuche et al. / energy procedia ( ) – . case study in the last decade in mexico public policies were applied that generated an accelerate growth in cities. the house research and documentation center s.c. (centro de investigación y documentación de la casa, s.c., ) [ ] reported the existence of more than million dwellings in mexico. since the vast majority of these existing dwellings are low-cost, we will use this type of dwelling as our case of study. . . location the building selected as a case study is located in the city of hermosillo, in the northwestern state of sonora. its geographical location is at º ´ north latitude and º ´ west longitude, with an elevation of meters above the sea level. hermosillo has a dry warm climate with temperatures that reach a maximum high of °c during the months of may, june, july, august and september, while during the winter season it can reach temperatures of °c. the annual precipitation is mm., and the city is characterized for having a clear sky with high solar radiation most days of the year. fig. . monthly diurnal averages of hermosillo, sonora. [ ] maría g. alpuche et al. / energy procedia ( ) – . . building description the low-cost dwelling has an area of construction of . m , which is representative of the majority of dwellings constructed in the last decade in the city. it has two bedrooms, dining-living area, kitchen, and one bathroom in one level. see figure . fig. . schematic representation of analyzed dwelling construction system. the dwelling is built with cm thick red brick walls covered by a . cm layer of gypsum plaster in both interior and exterior faces. the roof is a cm thick reinforced concrete slab with . cm of polyurethane insulation and a simple concrete compression layer of cm on top. the interior finish (ceiling) is made of a . cm layer of gypsum plaster, and the exterior finish is a layer of elastomeric. table , shows thermal properties of the construction system. table . description of system construction and u values used in thermal simulation component description u-factor (w/m k) walls red brick of cm thick with a thick finish of gypsum plaster of . cm as interior and exterior . roof reinforced concrete of cm thick with polyurethane insulation of . cm, a simple concrete compression layer of cm, gypsum plaster of . as interior finish and a layer of elastomeric as exterior finish . maría g. alpuche et al. / energy procedia ( ) – . . simulation the thermal analysis was performed using the software design builder, and taking advantage of its interface with the calculation program energy plus. the energy plus software is a whole building energy simulation program, that calculation methodology is based on fundamental heat balance principles. for this analysis, the dwelling unit was considered to be one single zone, without occupants and the same construction system for both cases without and with air conditioning, only change in the envelope the solar absorptances coefficients. fig. . sketch of the dwelling in the software design builder. to perform the analysis of the dwelling unit with air-conditioning, ventilation was not considered, only infiltration and air change. we used a mini-split system compact unit zone cooling with a cop of . and a design temperature of °c. this air-conditioning unit was obtained from the energy plus database. for this analysis, cooling was considered to be on all year, while heating was never used. in order to test the influence of absorptance in the envelope of the building, we used the same model but modified the coefficient values for the solar absorption of the building envelope. in this simulation, we used a coefficient of . and . , and a coefficient of . for the roof and walls. . results the simulation was performed for the whole typical year in an hourly basis, for both cases: with and without air conditioning. for the purpose of this article, we present the values obtained during one week in the month of january, which corresponds to the winter season; and one week in the month of july, which corresponds to the summer season. figure shows the results for the case without air conditioning during the week from the th to the th of january. the graph shows a direct effect of the solar absorption coefficient over the indoor temperature. during the hours of the day where the outdoor temperature is higher, which correspond to maría g. alpuche et al. / energy procedia ( ) – the hours of the day when solar radiation is also higher, the indoor temperatures have a difference of up to °c. this difference is caused by the absorptance coefficient of the material of the building envelope. fig. . simulated indoor temperatures vs outdoor temperature for different solar absorptances, from january th to th, without a/c fig. . simulated indoor temperatures vs outdoor temperature for different solar absorptances, from july th to rd, without a/c. maría g. alpuche et al. / energy procedia ( ) – similarly, figure shows the results for the case without air conditioning during the week from the th to the rd of july, which corresponds to the summer season. the results are similar to those of the winter season, but the difference in outdoor and indoor temperatures is of less than . °c. fig. . consumption of electricity for cooling dwellings with different solar absorptance coefficients in their building envelope from the simulation of the dwelling with air conditioning, we obtained the amount of electricity necessary to maintain an interior temperature of °c. the results are shown in figure . with a simple change of color in the interior finishes, which would correspond to a different value of solar absorptance, the amount of energy consumed can be increased or decreased. during the months when air conditioning is necessary, a variation of the solar absorptance coefficient from . to . represents a % reduction in energy consumption; while a variation from . to . represents a % reduction. maría g. alpuche et al. / energy procedia ( ) – conclusions this paper presents the evaluation of the interior thermal behavior of a low-cost dwelling, by varying the solar absorptance coefficients of the building exterior finish. the results show that, in a warm climate region with high levels of solar radiation, the use of colors with low solar absorptance coefficients in the building envelope can significantly reduce heat gains in buildings. the colors with the lowest solar absorptance coefficients correspond to the lightest colors. this study builds on research that supports the need to use constructive systems that take into account the climate context in order to produce more efficient buildings, by providing evidence that the absorptance coefficient of the building’s exterior finishes is a relevant factor in the thermal behavior of the interior of buildings. we conclude that, in order to achieve the optimum efficiency of a building located in dry warm weather, architects and designers must take into consideration architectural design strategies that include formal, functional and technical aspects, using passive and active strategies, which can reduce energy consumption required for interior conditioning. acknowledgements to fondo sectorial de investigación para la educación and to consejo nacional de ciencia y tecnología for their kind financial support to project cb- / . to programa de mejoramiento del profesorado to subsecretaría de educación superior for their kind financial support to project: reglamentación y normatividad para arquitectura bioclimática. references [ ] sener. balance nacional de energía , subsecretaría de planeación energética y desarrollo tecnológico, méxico; . [ ] shariah a, shalabi b, rousan a, tashtoush b. effects of absorptance of external surfaces on heating and cooling loads of residential buildings in jordan. energy convers. mgmt. ; ( / ): - . [ ] berdahl p, bretz se. preliminary survey of the solar reflectance of cool roofing materials. energy and buildings. ; : - . [ ] suehrcke h, peterson el, selby n. effect of roof solar reflectance on the building heat gain in a hot climate. energy and buildings. ; : - . [ ] yao j, yan ch. effects of solar absorption coefficient of external wall on building energy consumption. word academy of science, engineering and technology. ; . [ ] ma y, li y, zhu b. analysis of the thermal properties of air-conditioning type building materials. solar energy. , : - . [ ] libbra a, tarozzi l, muscio a, corticelli m a. spectral response data for development of cool coloured tile coverings. optics & laser technology. , : - . [ ] santamouris m, synnefa a, karlessi t. using advanced cool materials in the urban built environment to mitigate heat islands and improve thermal comfort conditions. solar energy. , : - . [ ] synnefa a, karlessi t, gaitani n, santamouris m, assimakopoulos d n, papakatsikas c. experimental testing of cool colored thin layer asphalt and estimation of its potential to improve the urban microclimate. building and environment. , : - . maría g. alpuche et al. / energy procedia ( ) – [ ] zinzi m, carnielo e, agnoli s. characterization and assessment of cool coloured solar protection devices for mediterranean residential buildings application. energy and buildings. , : - . [ ] takebayashi h, moriyama m, sugihara t. study on the cool roof effect of japanese traditional tiled roof: numerical analysis of solar reflectance of unevenness tiled surface and heat budget of typical tiled roof system. energy and buildings. , : - . [ ] fundación cidoc y sociedad hipotecaria federal. el estado de la vivienda en méxico. méxico, . [ ] ucla. climate consultant v. . , energy design tool, software, california, e. u, . wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ numerical simulation of indoor thermal environment effected by air supply temperature and grille angle on stratum ventilation in a typical office procedia engineering ( ) – available online at www.sciencedirect.com - © published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of ishvac-cobee doi: . /j.proeng. . . sciencedirect th international symposium on heating, ventilation and air conditioning (ishvac) and the rd international conference on building energy and environment (cobee) numerical simulation of indoor thermal environment effected by air supply temperature and grille angle on stratum ventilation in a typical office hangyu zhaoa, zeqin liua,b,c, *, zhenjun zuoa akey laboratory of tianjin refrigeration technology, tianjin university of commerce, tianjin, , china bengineering research center of the ministry of education of refrigeration technology cengineering center of tianjin refrigeration technology abstract based on for indoor thermal environment and human thermal comfort, the air distribution in a typical air-conditioned office in the mode of stratum ventilation was simulated with the fluent airpak simulation software in this paper. the variation regularity of indoor thermal environment effected on air supply temperature and grille angle was explored and human thermal comfort and energy efficiency was analyzed. the following conclusions could be obtained. under this condition with air supply angle and other parameters unchanging, air conditioning room temperature appeared overall upward trend with the air temperature increased; the average indoor wind speed appeared overall upward trend; the average indoor predicted percentage of dissatisfaction ppd decreased firstly and then increased. when the air temperature was , ppd achieved the minimum value. when the air supply temperature and other parameters were unchanging, the average value of ppd was increased firstly and then decreased with the air supply angle changing. when the air supply angle was degrees, ppd achieved the maximum value. © the authors.published by elsevier ltd. peer-review under responsibility of the organizing committee of ishvaccobee . keywords: stratum ventilation; numerical simulation; air supply angle; thermal comfort * corresponding author. tel.: + - - ; fax: + - - . e-mail address: liuzq@tjcu.edu.cn © published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of ishvac-cobee http://crossmark.crossref.org/dialog/?doi= . /j.proeng. . . &domain=pdf http://crossmark.crossref.org/dialog/?doi= . /j.proeng. . . &domain=pdf hangyu zhao et al. / procedia engineering ( ) – . introduction the main nomenclatures of this article were as follows: nomenclature density, kg/m u velocity, m/s laminar dynamic viscosity, kg/(m·s) t turbulent dynamic viscosity, kg/(m·s) t time dissipation rate k turbulent kinetic energy x coordinate ,i j free index ppd predicted percentage of dissatisfaction pmv predicted mean vote with the growth of environmental pollution and world energy crisis, asian countries have put forward that the summer indoor air temperature should be appropriately raised to response the energy crisis and mitigate the greenhouse effect. the mainland of china raised the summer guidance temperature of public buildings to , and with the increase of indoor design temperature, the ansi/ashrae standard - also recommended that the thermal uncomfortable feeling be eliminated by increasing the summer wind speed [ ]. for indoor persons, the air quality in human breathing zone was directly related to the human body health and work efficiency[ ]. with the consideration of these factors, a concept of stratum ventilation that applied to the small room was proposed by the city university of hong kong, zhang lin [ ]. stratum ventilation was a way of sending fresh air directly to the breathing zone by the wind-gap situated on the side wall and a little above the working area. so far, the amount of the foreign research reports in this field was rather little. t.tchow, c.ftsang, k.ffong, l.s.chan by experimental and numerical studies showed that the design temperature of air-conditioned room could be improved by the stratum ventilation without compromising thermal comfortable feeling [ ]. tian lin’s study proved that good thermal comfortable feeling could be achieved by stratum ventilation [ ]. xi'an jiaotong university, wang fenghao et al. have explored the airflow characteristics of the office stratum ventilation and displacement ventilation. they also have analysed the work zone under the two ventilation ways and temperature field, velocity field, co concentration field et al. near human bodies. professor zhang lin reported a high temperature air conditioning study under stratum ventilation [ ]. . theoretical model based on the content of this study, the mathematical model for numerical simulation would be simplified. it was that there were no other heat source and solid roadblock in addition to indoor multi-point heat sources, in the same time making the following assumptions: ) indoor fluid was steady and incompressible; ) the air after being treated by air-conditioning was delivered into air conditioning room via inlet and mixed thoroughly with indoor air. the variation regular pattern of indoor temperature field could be obtained by fluent airpak simulation software. rng k- ɛ turbulence model was set as flow model, which was similar to the standard k-ɛ model but more accurate. the impact of low reynolds number was also considered in this model [ ]. the transport equations for k and ε were as follows [ ]: ( ) ti k i j k j k k ku p t x x x ( ) hangyu zhao et al. / procedia engineering ( ) – * ( ) t i k i j j u c p c t x x x k k ( ) where, * c c c , sk , ij ijs s s and ji ij j i uu s x x . kp was the production of turbulent kinetic energy. ijs was the mean rate of strain tensor. the values of the constants were derived as follows: . c , . k , . , . c , . c , . , . . for the calculation of predicted percentage of dissatisfaction ppd, programs should be firstly compiled by matlab mathematics calculated software. then calculated the predicted mean vote pmv that was put forward by professor fanger in , and in the end the ppd value would be predicted through the following formula [ ]: . . pmv pmv ppd e ( ) . numerical simulation model in order to analyse the numerical simulation results of indoor air conditioning with the experimental data, the physical model of numerical simulation was established in accordance with the geometry dimension of experimental air-conditioned room, namely . m (length, x) × . m (width, y) × . m (height, z). the room set point heat sources and analog people that had fixed heat. the article supposed that the building envelopes’ heat transfer be simply added to the heat of chamber point sources to explore this issue’s study subjects. fig. . was the model chart of air conditioning air supply. fig. . the model of air conditioning air supply . discussion fig. . to fig. . were distribution charts of air temperature in y-z plane with the air supply temperature was constant , and respectively, the air supply angles were degrees, degrees, degrees, degrees, degrees. their temperature tangent planes lied in three section positions (x= . , . , . ) where measurement points were arranged in experiment. as could be seen from the figures, at different air supply angles, the temperature within the space of human activity conformed the requirements of the design temperature basically. only when the air supply angles were degrees and degrees, the indoor temperature was high, and the temperature stratification at vertical direction was very obvious under all conditions, and the return air’s temperature was the highest. when the air supply angle was degrees, all temperature of an air-conditioned room was the most evenly distributed, but the energy utilization hangyu zhao et al. / procedia engineering ( ) – factor was lower, and was not conducive for energy saving. as the air supply angles of degrees and degrees, the temperature difference of head and foot was smaller, and the thermal comfort was better. fig. . the air supply angle was degrees fig. . the air supply angle was degrees fig. . the air supply angle was degrees fig. . the air supply angle was degrees fig. . the air supply angle was degrees fig. . the ppd in the air-conditioned room hangyu zhao et al. / procedia engineering ( ) – fig. . showed that under the condition of the air supply temperature unchanging, indoor predicted percentage of dissatisfaction ppd appeared an overall trend of changing from increase to decrease with the increase of air supply angles. when the grille angle was degree, the ppd reached a maximum value, which larger than %, but did not meet the requirements of human thermal comfort. when the air supply angles were degrees, degrees, degrees, degrees, under the condition of different air supply temperature, the indoor predicted percentage of dissatisfaction ppd was lower than %, meeting human thermal comfort requirements. fig. . to fig. . were distribution charts of air temperature in y-z plane with the air supply angle was constant degrees, and respectively, the air supply temperature was , , , . under the air supply way of stratum air conditioning, when air supply angles and other parameters unchanging, indoor temperature and average wind speed in air-conditioned room appeared overall upward trend with the air supply temperature increased. . conclusion in the air-conditioned design, the analysis to the indoor thermal environment and thermal comfort could provide a reference for the designers selecting the appropriate stratum air supply temperature and air supply angle in design, which could improve the thermal comfort of the stratum air supply room. by exploring the impact of the stratum air supply temperature and air supply angle to indoor air temperature and the value of ppd, this paper could get the following conclusions: under the air supply way of stratum air conditioning, when the air supply angles and other parameters unchanging, air conditioning room temperature appeared overall upward trend with the air temperature increased; the average indoor wind speed appeared overall upward trend; the average indoor predicted percentage of dissatisfaction ppd decreased firstly and then increased. when the air temperature was , ppd achieved the minimum value. when the air supply temperature and other parameters were unchanging, the average value of ppd was increased firstly and then decreased with the air supply angle changing. when the air supply angle was degrees, ppd achieved the maximum value. fig. . the air supply temperature was fig. . the air supply temperature was fig. . the air supply temperature was fig. . the air supply temperature was hangyu zhao et al. / procedia engineering ( ) – acknowledgement this study was supported by the fund program of the development of science and technology of tianjin municipal education commission under the contract no. . references [ ] ashrae, ansi/ashrae standard - , thermal environmental conditions for human occupancy. american society of heating, refrigerating, and air-conditioning engineers inc. atlanta, . [ ] z.q. liu, g. li, c.x. zheng, the simulation and calculation of indoor thermal environment and the ppd evaluation index affected by three typical air-conditioning supply modes, hvac&r research. ( ) - . [ ] z. lin, t.t. chow, stratum ventilation-a solution of high temperature air condition, journal of chemical industry and engineering. ( ) - . [ ] z. lin, t.t. chow, c.f. tsang, k.f. fong, l.s. chan, stratum ventilation–a potential solution to elevated indoor temperatures, building and environment. ( ) – . [ ] l. tian, z. lin, j. liu, q.w. wang, numerical study of indoor air quality and thermal comfort under stratum ventilation, progress in computational fluid dynamics. , - . [ ] m.l. zhang, three-dimensional simulation of meandering river based on -d rng k-ɛ turbulence model, journal of hydrodynamics. ( ) - . [ ] yakhot v, orszag sa, thangam s, t.b. gatski, c.g. speziale, development of turbulence models for shear flows by a double expansion technique, physics of fluids a. ( ) - . [ ] h.z. zhao, a.g. li, prediction of vertical temperature distribution in rooms with upward air supply, hv & ac. ( ) - . hindawi publishing corporation journal of nanomaterials volume , article id , pages doi: . / / editorial nanocrystals-related synthesis, assembly, and energy applications bo zou, william w. yu, jaetae seo, ting zhu, and michael z. hu state key laboratory of superhard materials, jilin university, changchun , china college of electronic science and engineering, jilin university, changchun , china department of physics, hampton university, hampton, va , usa philips lumileds lighting company, san jose, ca , usa oak ridge national laboratory, nuclear science and technology division, oak ridge, tn , usa correspondence should be addressed to bo zou, zoubo@jlu.edu.cn received february ; accepted february copyright © bo zou et al. this is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. during the past decades, nanocrystals have attracted broad attention due to their unique shape- and size-dependent physical and chemical properties that differ drastically from their bulk counterparts. hitherto, much effort has been dedicated to achieving rational controlling over the morphology, assembly, and related energy applications of the nanomaterials. therefore, the ability to manipulate the morphology, size, and size distribution of inorganic nanomaterials is still an important goal in modern materials physics and chemistry. especially, the world’s demand for energy supply is causing a dramatic escalation of social and political unrest. likewise, the environmental impact of the global climate change due to the combustion of fossil fuel is becoming increasingly alarming. these problems compel us to search for effective routes to build devices that can supply sustainable energy, with not only high efficiency but also environmental friendship. one of ways to relieve the energy crisis is to exploit devices based on renewable energy sources, such as solar energy and water power. aiming at this exploration, the primary stage requires the design of appropriate strategies for the synthesis of high-quality nanocrystals with respect to size uniformity and superior electrochemical performances. as a consequence, we orga- nize the current special issue for journal of nanomaterials to provide the authors with a platform and readers with the latest achievements of nanocrystals-related synthesis, assembly, and energy applications. one of the papers presents the synthesis of single crys- talline znte hierarchical nanostructures by a simple thermal evaporation technology and discussed the corresponding growth mechanism. another paper reports the synthesis of cdse and cdte quantum dots (qds) from the bulk cdse and cdte material by evaporation/cocondensation using the solvated metal atom dispersion technique and refined digestive ripening. it is found that pl quantum yield of cdse qds and cdte qds upon covering with a zns shell was greatly enhanced. another paper presents that nanosize tib whiskers were successfully obtained by micropyretic synthesis which is considered as the one of the novel energy-saving processing techniques. the diffusion- controlled reaction mechanism was proposed in this study. one more paper presents the progress of tio nanocrys- tals doped with rare earth ions in the aspect of nano- optic and photocatalytic properties. another paper presents a search article in which zno nanoparticles were successfully synthesized at room temperature via mechanical milling, and the quantum size effect was interpreted in terms of absorption and pl spectra. an additional paper presents that zno micro-/nanocombs have been successfully synthe- sized on cu substrate using a highly repeatable catalyst- free chemical vapor deposition method. the cathodolu- minescence spectrum was also measured on an individual zno comb and only a broad strong green emission band was observed. another paper presents that mesoporous journal of nanomaterials nanosheets of single-crystalline ni(oh) were successfully prepared via a facile hydrothermal method. furthermore, single-crystalline nio mesoporous nanosheets were also obtained through a thermal decomposition of the obtained ni(oh) . another paper presents that basn(oh) nanorods were synthesized via a novel two-step technique involving the preparation of precursor na sn(oh) crystals in aqueous solution via hydrothermal method and the ion-exchange reaction between na sn(oh) crystals and ba + solution that followed, assisted by ultrasonic treatment. in addition, the powder basno has been obtained by thermal treatment using basn(oh) nanorods as precursor. the ninth paper presents a microwave plasma synthesis of orthorhombic α- moo microplates with photoluminescence in a wavelength range of – nm. one more paper presents that various copper hierarchical structures assisted by surfactants were successfully fabricated combined with the electrodeposition technique and the possible formation mechanism of the copper hierarchi- cal structures with various morphologies was discussed. another paper presents that multicomponent mg-based nano-quasicrystals were directly prepared through a simple route by using a water-cooled wedge-shaped copper mould. an additional paper describes the research results on nanometers sizes subwavelength nanostructure fabrication by uv-curing of special nanocomposite material with self- organization and light self-focusing effects. obtained results will be useful for diffraction limit overcoming in projection lithography as well as for deep lithography technique. another paper presents that ionogels were prepared by ultrasonic-assisted sol-gel process and it has been found that ultrasonic irradiation affected the gelation dynamics and kinetics in pore parameters and vibrational properties of the il. acknowledgments the editors would like to thank the authors for their contri- butions to this special issue, the reviewers for their time and dedication. bo zou william w. yu jaetae seo ting zhu michael z. hu submit your manuscripts at http://www.hindawi.com scientifica hindawi publishing corporation http://www.hindawi.com volume corrosion international journal of hindawi publishing corporation http://www.hindawi.com volume polymer science international journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume ceramics journal of hindawi publishing corporation http://www.hindawi.com volume composites journal of nanoparticles journal of hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume international journal of biomaterials hindawi publishing corporation http://www.hindawi.com volume nanoscience journal of textiles hindawi publishing corporation http://www.hindawi.com volume journal of nanotechnology hindawi publishing corporation http://www.hindawi.com volume journal of crystallography journal of hindawi publishing corporation http://www.hindawi.com volume the scientific world journal hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume coatings journal of advances in materials science and engineering hindawi publishing corporation http://www.hindawi.com volume smart materials research hindawi publishing corporation http://www.hindawi.com volume hindawi publishing corporation http://www.hindawi.com volume metallurgy journal of hindawi publishing corporation http://www.hindawi.com volume biomed research international materials journal of hindawi publishing corporation http://www.hindawi.com volume n a n o m a te ri a ls hindawi publishing corporation http://www.hindawi.com volume journal of nanomaterials effects of ketone bodies on brain metabolism and function in neurodegenerative diseases international journal of molecular sciences review effects of ketone bodies on brain metabolism and function in neurodegenerative diseases nicole jacqueline jensen ,* , helena zander wodschow , malin nilsson and jørgen rungby , department of endocrinology, bispebjerg university hospital, copenhagen, denmark; helenazw@outlook.com (h.z.w.); malin.sofia.desiree.nilsson@regionh.dk (m.n.); joergen.rungby@regionh.dk (j.r.) copenhagen center for translational research, copenhagen university hospital, bispebjerg and frederiksberg, copenhagen, denmark * correspondence: nicole.jacqueline.jensen@regionh.dk received: november ; accepted: november ; published: november ����������������� abstract: under normal physiological conditions the brain primarily utilizes glucose for atp generation. however, in situations where glucose is sparse, e.g., during prolonged fasting, ketone bodies become an important energy source for the brain. the brain’s utilization of ketones seems to depend mainly on the concentration in the blood, thus many dietary approaches such as ketogenic diets, ingestion of ketogenic medium-chain fatty acids or exogenous ketones, facilitate significant changes in the brain’s metabolism. therefore, these approaches may ameliorate the energy crisis in neurodegenerative diseases, which are characterized by a deterioration of the brain’s glucose metabolism, providing a therapeutic advantage in these diseases. most clinical studies examining the neuroprotective role of ketone bodies have been conducted in patients with alzheimer’s disease, where brain imaging studies support the notion of enhancing brain energy metabolism with ketones. likewise, a few studies show modest functional improvements in patients with parkinson’s disease and cognitive benefits in patients with—or at risk of—alzheimer’s disease after ketogenic interventions. here, we summarize current knowledge on how ketogenic interventions support brain metabolism and discuss the therapeutic role of ketones in neurodegenerative disease, emphasizing clinical data. keywords: ketone bodies; neurodegeneration; cognition; cerebral metabolism; ketogenic diet; ketone supplements; astrocytes; sglt- inhibitors . introduction the human brain requires a significant amount of energy for normal brain function and accounts for about % of the body’s total energy expenditure at rest, despite the fact that the brain only represents ~ % of the total body weight [ ]. most of the brain’s energy consumption is derived from glucose oxidation and is predominantly used to support synaptic transmission, including the maintenance of ion gradients [ , ]. in addition to the energy requirements for neuronal signalling, other cellular processes such as remodelling of the cytoskeleton, synthesis of phospholipids, and axonal transport, also require atp [ ]. therefore, an adequate and continuous supply of energy is necessary to maintain brain cellular function since only a limited amount of glycogen is stored inside the brain [ ]. this is emphasized in pathological conditions where brain metabolism is disturbed, e.g., in glucose transporter type (glut- ) deficiency resulting in impaired cerebral glucose uptake, where clinical symptoms may manifest as seizures, movement disorders, and cognitive impairments [ ]. while the brain primarily relies on glucose as the main fuel, other substrates may contribute to metabolism, especially when glucose supply is restricted or inadequate, e.g., during fasting and low int. j. mol. sci. , , ; doi: . /ijms www.mdpi.com/journal/ijms http://www.mdpi.com/journal/ijms http://www.mdpi.com https://orcid.org/ - - - https://orcid.org/ - - - x http://www.mdpi.com/ - / / / ?type=check_update&version= http://dx.doi.org/ . /ijms http://www.mdpi.com/journal/ijms int. j. mol. sci. , , of carbohydrate diets [ , ]. ketone bodies, together with lactate, are the main alternative fuels for the brain and both are able to cross the blood–brain barrier through monocarboxylate transporters (mcts) in endothelial cells and astroglia [ ]. plasma ketone levels are usually low after an overnight fast (< . mm) and contribute to less than % of the brain’s metabolism [ ]. however, during prolonged fasting ( – weeks), ketone body levels rise significantly and are able to contribute almost % of the brain’s energy requirement, thereby replacing glucose as the main fuel [ ]. ketonemia can be achieved in non-fasting states by ketogenic diets or by the ingestion of supplements in the form of ketogenic medium-chain fatty acids (mcfa) or exogenous ketone esters or salts. when plasma levels of ketone bodies are raised either by fasting, diet or infusion, they are transported to the brain and metabolized in a concentration-dependent manner [ ], consequently offering a strategy to alter or enhance cerebral metabolism in disorders with a disturbed glucose metabolism. the ketogenic diet was developed in the s as a treatment for epilepsy due to early observations of an antiseizure effect [ ]. during the last decade, the interest in ketogenic diets and other ketogenic treatments has increased rapidly, and ketone bodies are now thought to be a potential therapeutic strategy in many disorders such as cancer, diabetes, cardiovascular disease, and neurodegeneration [ , ]. a growing number of preclinical and clinical studies exist on different ketogenic approaches in neurodegenerative diseases, especially alzheimer’s disease (ad). one common feature in diseases characterized by neurodegeneration is disruption of the brain’s energy metabolism. in ad, parkinson’s disease (pd), amyotrophic lateral sclerosis (als), and huntington disease (hd), glucose hypometabolism in affected brain regions is prominent, which correlates to disease severity [ – ]. therefore, approaches which support brain energetics, such as ketone treatments, may slow disease progression or even delay or prevent disease onset if initiated early enough. a comprehensive review on the status and prospects of different energetic strategies in neurodegeneration was recently published [ ]. in this review, we focus on different ketogenic approaches and describe the metabolic actions of ketone bodies in the brain and highlight key clinical data that support the neuroprotective effects of ketones in diseases of neurodegeneration. . ketone bodies reaching the brain during fasting, free fatty acids are mobilized from adipocytes and transported to the liver where they contribute to the synthesis of ketone bodies [ ]. this process is dependent on low insulin levels, which enhances lipolysis in white adipose tissue due to the suppressed insulin-induced inhibition on hormone sensitive lipase. in hepatocytes, they subsequently undergo beta-oxidation that may initiate ketogenesis [ ]. due to the need of transporters for the entry of long chain fatty acids to the mitochondrial matrix, this could be a limiting step for ketosis during a ketogenic diet. interestingly, mcfa are not dependent on the transporter protein for mitochondrial entry [ ]. . . the synthesis of ketone bodies in the liver hepatocytes are the main site for the synthesis of ketones but the process may also occur, albeit to a minor extent, in the kidneys and in astrocytes [ ]. a high level of acetyl coenzyme a (acetyl-coa) is essential for ketogenesis, and is obtained mainly through a high supply of free fatty acids, which can lead to a surplus production of acetyl-coa not entering the tricarboxylic (tca) cycle for atp generation but leading to the formation of ketone bodies [ ]. hence, ketone bodies are mainly derived from fatty acids via beta-oxidation; however, amino acids (particularly leucine) may contribute about % of the total ketone body production in the post-absorptive state [ ]. ketogenesis requires the action of at least three enzymes: (i) mitochondrial acetoacetyl-coa thiolase, (ii) mitochondrial -hydroxy- -methylglutaryl-coa (hmg-coa) synthase (hmgcs ), and (iii) hmg-coa lyase, which form the ketone body, acetoacetate (figure ; hepatocyte). int. j. mol. sci. , , of int. j. mol. sci. , , x for peer review of another acetyl-coa via a reaction with hmgcs , hence forming hmg-coa. this reaction is the rate- limiting step, which is regulated by insulin and glucagon, which inhibit and facilitate hmgcs transcription via forkhead transcriptional factor foxa [ ]. the enzyme hmg-coa lyase subsequently removes an acetyl-coa from hmg-coa to produce the ketone body acetoacetate, which can either undergo spontaneous degradation to acetone (another ketone body with minimal metabolic contribution) or form the ketone body beta-hydroxybutyrate (bhb) [ ], the most abundant ketone body in the human circulation [ ]. this occurs through an enzymatic reaction with beta-hydroxybutyrate dehydrogenase (bdh), requiring a hydrogen donated from the nad+/nadh couple. acetoacetate and bhb are not utilized in the liver, as it lacks important enzymes for ketolysis, but are instead released into the circulation for metabolism in extrahepatic tissues. rodents on a calorie-restricted diet increase gene expression of hmgcs in the liver, and in cases where the calorie-restricted diet is ketogenic, upregulations of hmgcs are also found in brain tissue [ ]. figure . pathways involved in synthesis and catabolism of ketone bodies. acac, acetoacetate; acetyl- coa, acetyl coenzyme a; bhb, beta-hydroxybutyrate; bhd, beta-hydroxybutyrate dehydrogenase; ffa, free fatty acids; hmg-coa, -hydroxy- -methylglutaryl-coa; hmgcs , -hydroxy- - methylglutaryl-coa synthase ; mcfa, medium-chain fatty acids; mct, monocarboxylate transporter; scot, succinyl-coa: -ketoacid coenzyme a transferase; tca, tricarboxylic acid cycle. . . ways of increasing the concentration of circulating ketone bodies besides fasting, ketogenic diets and nutritional ketogenic supplements can increase the circulatory pool of ketone bodies. the ketogenic diet mimics the metabolic profile of fasting, due to the high consumption of lipids and very low intake of carbohydrates, which is usually restricted to less than – g/day [ ]. this relatively low energy contribution from carbohydrates enhances beta- oxidation and induces ketosis, in part owing to the low stimulus on beta-cells to induce insulin secretion. a quite high level of ketosis ( . mm) has been achieved previously by individuals on a classic ketogenic diet (lipid to protein + carbohydrate ratio of . : ) [ ]. however, adherence to ketogenic diets is difficult to accomplish and often poor [ ]. furthermore, ketogenic diets may be associated with adverse effects such as gastrointestinal problems, weight loss (which often should be avoided in neurodegenerative diseases), hyperlipidaemia, and may also result in vitamin and mineral deficiency, due to the strict diet regime [ ]. thus, ketogenic supplements may be more applicable in some patient groups. figure . pathways involved in synthesis and catabolism of ketone bodies. acac, acetoacetate; acetyl-coa, acetyl coenzyme a; bhb, beta-hydroxybutyrate; bhd, beta-hydroxybutyrate dehydrogenase; ffa, free fatty acids; hmg-coa, -hydroxy- -methylglutaryl-coa; hmgcs , -hydroxy- -methylglutaryl-coa synthase ; mcfa, medium-chain fatty acids; mct, monocarboxylate transporter; scot, succinyl-coa: -ketoacid coenzyme a transferase; tca, tricarboxylic acid cycle. the initial step of ketogenesis is the formation of acetoacetyl-coa, which is derived from two acetyl-coa by the enzyme thiolase. the newly produced acetoacetyl-coa is then combined with another acetyl-coa via a reaction with hmgcs , hence forming hmg-coa. this reaction is the rate-limiting step, which is regulated by insulin and glucagon, which inhibit and facilitate hmgcs transcription via forkhead transcriptional factor foxa [ ]. the enzyme hmg-coa lyase subsequently removes an acetyl-coa from hmg-coa to produce the ketone body acetoacetate, which can either undergo spontaneous degradation to acetone (another ketone body with minimal metabolic contribution) or form the ketone body beta-hydroxybutyrate (bhb) [ ], the most abundant ketone body in the human circulation [ ]. this occurs through an enzymatic reaction with beta-hydroxybutyrate dehydrogenase (bdh), requiring a hydrogen donated from the nad+/nadh couple. acetoacetate and bhb are not utilized in the liver, as it lacks important enzymes for ketolysis, but are instead released into the circulation for metabolism in extrahepatic tissues. rodents on a calorie-restricted diet increase gene expression of hmgcs in the liver, and in cases where the calorie-restricted diet is ketogenic, upregulations of hmgcs are also found in brain tissue [ ]. . . ways of increasing the concentration of circulating ketone bodies besides fasting, ketogenic diets and nutritional ketogenic supplements can increase the circulatory pool of ketone bodies. the ketogenic diet mimics the metabolic profile of fasting, due to the high consumption of lipids and very low intake of carbohydrates, which is usually restricted to less than – g/day [ ]. this relatively low energy contribution from carbohydrates enhances beta-oxidation and induces ketosis, in part owing to the low stimulus on beta-cells to induce insulin secretion. a quite high level of ketosis ( . mm) has been achieved previously by individuals on a classic ketogenic diet (lipid to protein + carbohydrate ratio of . : ) [ ]. however, adherence to ketogenic diets is difficult to accomplish and often poor [ ]. furthermore, ketogenic diets may be associated with adverse effects such as gastrointestinal problems, weight loss (which often should be avoided in neurodegenerative int. j. mol. sci. , , of diseases), hyperlipidaemia, and may also result in vitamin and mineral deficiency, due to the strict diet regime [ ]. thus, ketogenic supplements may be more applicable in some patient groups. dietary supplements of mcfa also induce ketosis. this happens relatively soon after ingestion, as this group of fatty acids is absorbed directly into the portal vein instead of the lymphatic system (in contrast to long-chain fatty acids) and is consequently rapidly converted to ketones via beta-oxidation in the liver [ ]. the most ketogenic mcfa are caprylic acid (c ) and capric acid (c ), which are found in coconut oil and palm kernel oil [ ]. however, the concentration of these lipids is relatively low in the oils and interventions with coconut oils only raise ketone body levels modestly [ ]. products with higher concentrations of caprylic and capric acid have been developed and induce a ketosis of ~ . mm [ ]. another alternative to the ketogenic diet is intake of exogenous ketone esters and salts, which significantly increase ketone levels to > mm post ingestion, with the ketone ester being most potent in raising circulating ketones even while consuming regular meals [ , ]. ketone salts often consist of a mixture of the d- and l-isoform of bhb, though the metabolic contribution of the l-isoform is poorly understood. all three approaches (ketogenic diet, mcfa, and exogenous ketone bodies) have been used in studies of neurodegenerative diseases, with most employing mcfa. it should be noted that mcfa may possess neuroprotective effects not related to ketonemia, since mcfa are able to cross the blood–brain barrier (bbb) and function as substrates for energy metabolism [ ]. furthermore, studies indicate that the mcfa, capric acid, may have the ability to improve mitochondrial function and reduce neuronal hyperactivity, which is often seen in ad, by inhibiting glutamatergic ampa receptors [ ]. . . ketone bodies entering the brain via monocarboxylate transporters the uptake of ketone bodies across the bbb is carrier-dependent and unlike glucose transport, not increased by neuronal activity, but instead related to concentrations in the circulation [ ]. mcts are the only known transporters for ketone bodies and are distributed throughout the brain [ ]. studies in rodents have revealed that mct expression is quite distinct between cell types, with the mct -isoform located at the bbb on endothelial cells and astroglia [ ]. further, astrocytes also express mct , which like mct has a relatively low affinity for bhb [ ]. in contrast, neurons almost exclusively express the mct isoform, which possesses a high affinity for bhb [ ]. the expression of mct in neurons is co-localized to the mitochondria-rich postsynaptic density structures [ ], suggesting that the transporter may play an important role in synaptic transmission [ ]. together this suggests that neurons, and to a certain extent also astrocytes, have the capacity to take up ketone bodies. studies on tissue samples report that the mct and expression is quite similar in human brains compared to animal models [ , ]. the transport capacity of ketone bodies over the bbb in rodents is up-regulated by fasting [ ], which may also be the case in humans [ ]. the enhanced capacity is likely due to an upregulation of mct expression, which is found in rodents both after a ketogenic diet [ , ] and after exercise [ ]. . . the catabolism of ketone bodies in neuronal and glial cells once bhb and acetoacetate have been transported into the brain, they are converted back into acetyl-coa, which enters the tca cycle for atp generation (figure ; neuron). the conversion occurs inside the mitochondria where bhb is transformed into acetoacetate by the reversible action of bdh using nad+ and subsequently forming nadh. acetoacetate is catabolized to acetoacetyl-coa by succinyl-coa: -ketoacid coenzyme a transferase (scot). mrna levels of scot are detectable in all human tissues excepts the liver [ ]; therefore, the liver is unable to utilize ketone bodies as an energy substrate. acetoacetyl-coa is then converted back into two acetyl-coas ready to enter the tca by the reversible action of thiolase (the first enzyme of ketogenesis). in contrast to glucose, this conversion of bhb and acetoacetate into an oxidizable form does not require atp [ , ]. in the developing rodent brain, cultured neurons, astrocytes and oligodendrocytes were all able to utilize int. j. mol. sci. , , of ketone bodies for oxidative metabolism at rates far greater than they utilized glucose. however, neurons and oligodendrocytes seemed to be more efficient in oxidizing ketones than astrocytes [ ]. . . glial–neural compartment mode for ketone body supply to neurones glycolysis in astrocytes results in lactate production, supplying a source of energy for neurons, termed the astrocyte neuron lactate shuttle [ ]. further, fatty acids may cross the bbb, thereby reaching astrocytes closely connected to neuronal structures [ ]. in astrocytes, degradation of fatty acids results in ketone body release to neighbouring neurons [ ]. thus, not only exogenous, but also endogenous ketone bodies can serve as fuel for the brain (figure ; astrocyte). mcfa supplementation may cause different modulations to astrocyte metabolism, which either enhances astrocyte neuron lactate shuttle or accelerates ketogenesis in astrocytes depending on the mcfa applied [ ]. endogenous production of ketone bodies is regulated by amp-activated protein kinase (ampk) activity [ ]. like elsewhere in the body, ampk may be stimulated by -aminoimidazole- -carboxamide ribonucleotide (aicar) [ ] and metformin [ ], leaving a potential for pharmacological interventions. finally, ampk-activated ketogenesis in astrocytes is stimulated by both hypoxia [ ] and hypoglycaemia [ ]. . the effect of ketone bodies on brain metabolism . . ketone bodies affect brain metabolism in healthy individuals in humans, both acute and chronic increases in ketone body availability to the central nervous system cause massive changes in cerebral fuel metabolism. in healthy middle-aged subjects, an i.v. infusion of bhb caused approximately % decrease in cerebral glucose consumption while oxygen use was unchanged, suggesting that ketone bodies, even when supplied acutely, enter the brain and may be utilized immediately as an alternative fuel to glucose [ ]. similar cerebral metabolic changes have also been demonstrated in young individuals [ ], however, at lower infusion rates, and thus lower bhb concentrations, glucose uptake does not seem to be affected [ ]. together, this suggests an acute cerebral glucose-sparing effect when ketone availability is high. comparable metabolic adaptations, where ketones substitute glucose, have also been reported in individuals on ketogenic diets [ ]. during prolonged fasting, a more pronounced shift from glucose to ketone body metabolism is reported with acetoacetate and bhb supplying more than % of the brain’s energy [ ], thereby replacing glucose as the main fuel supply. availability seems crucial to cerebral uptake of ketone bodies during acute infusions in humans [ ], whereas animal studies suggest that adaptation to increased levels of ketone bodies during fasting is accompanied by an increase in the brain’s capacity for ketone uptake, at least partly explaining the vast increase in ketone uptake after prolonged fasting [ , ]. thus, both acute and chronic exposure to ketone bodies will increase the availability of alternative fuels for the brain. during resting conditions, ketone bodies replace other energy sources rather than supplement them, resulting in unchanged atp levels in the brain of healthy individuals [ ]. however, other metabolic adaptations may occur both acutely and after longer interventions. bough et al. found that rodents fed a calorie-restricted ketogenic diet, compared with an ad libitum control diet, for weeks exhibited an upregulation of transcripts encoding proteins related to energy metabolism, including mitochondrial proteins for oxidative phosphorylation. in addition, the ketogenic diet enhanced mitochondrial biogenesis, and elevated the phosphocreatine/creatine ratio in the hippocampus [ ], subsequently improving hippocampal metabolism. like in the acute setting in humans, the metabolic adaptations did not result in detectible changes in atp levels. when glucose availability is acutely reduced by experimental hypoglycemia, additional provision of ketones either by infusion or ingestion of mcfa preserves cognitive functions in patients with type diabetes and healthy individuals, and increases the glycaemic threshold for symptoms and the counter-regulatory hormone response (i.e., greater hypoglycemia was required for initiation) [ , ]. this suggests that ketone bodies are not only able to save glucose, but also support brain metabolism during energy crises without prior adaptations int. j. mol. sci. , , of from fasting. hence, treatments that elevate circulating ketones are suggested to have implications in disorders characterized by compromised glucose metabolism, such as neurodegenerative diseases. . . hypometabolism in neurodegenerative disease is ameliorated by ketone bodies most neurodegenerative diseases, including ad, pd, hd and als, are characterized by metabolic disturbances, which may be involved in both the development and progression of the disease [ ]. the neurodegenerative diseases share several pathologies, such as protein aggregation, mitochondrial dysfunction, oxidative stress, neuroinflammation and more (see [ ] for review), which may be induced by—or trigger—energy crisis. another common feature in neurodegenerative diseases is the loss of specific neurons (ad: pyramidal neurons in ammon’s horn of the hippocampus; pd: dopaminergic neurons from substantia nigra pars compacta in the basal ganglia; hd: enkephalin-positive medium spiny neurons from striatum in basal ganglia; als: fast-fatigable motor neurons in the spinal cord). these selective neurons have a high energy demand due to their long-range neuronal projections and extensive synaptic connections, making them more susceptible to metabolic disturbances [ ]. in both ad, pd, hd, and als, glucose uptake and/or consumption is compromised [ – , ]. hypometabolism may be caused by a reduced density or activity of terminal neuronal fields and/or reduced glial metabolism [ ] or by a reduced transport capacity [ ]. especially in ad, the glucose consumption monitored by f-fdg pet uptake correlates closely with cognitive performance and may be used as part of the diagnostic procedure [ ]. in addition, fuel shortage is prominent even years before any cognitive impairment may be diagnosed [ ], a phenomenon possibly mirroring the insulin resistance seen in obesity and type diabetes where similar reductions in cerebral glucose consumption are seen [ – ]. the physiological response to energy shortage, as seen during fasting, is fat degradation and ketone body formation, thereby supplying fuel to the brain [ ] and saving protein (the main source of gluconeogenesis) [ ]. supplying exogenous ketone bodies thus represents an intriguing means to mitigate cerebral metabolic disturbances which are found in most neurodegenerative diseases. notably, and contrasting to glucose, the cerebral metabolism of ketone bodies remains unchanged in early ad when comparing patients to healthy individuals [ , ]. additionally, exogenous supplies of ketone body donors that cross the bbb, particularly mcfa, may facilitate endogenous, intracerebral ketone body formation mediated by astrocytes [ ]. recently, it was reported that elevated ketone levels improve total energy metabolism in humans. fortier et al. [ ] demonstrated that mcfa supplementation for months could enhance cerebral ketone metabolism without affecting the metabolic rate of glucose, thus increasing total energy metabolism in patients with mild cognitive impairments. further, this intervention tended to improve some cognitive measures. similar metabolic improvements have been demonstrated in patients with ad after month of mcfa (both c and c ) supplementation [ ]. . . ketone bodies may support metabolism besides being a substrate disturbed glucose metabolism in association with oxidative stress is present early in disease progression of neurodegenerative diseases. this may trigger other abnormalities, such as reduced anti-oxidant defence and aggregation of misfolded proteins, thereby promoting further metabolic crisis and oxidative stress, eventually creating a vicious circle [ ]. furthermore, neuroinflammation is a common feature in neurodegenerative disease and may promote energy crisis [ ]. oxidative stress is characterized by an accumulation of reactive oxygen species (ros), due to overproduction or diminished elimination [ ]. ketone bodies may regulate ros balance through direct and indirect pathways. this is supported by in vitro studies, showing that ketone bodies may function as direct antioxidants, suppressing mitochondrial ros production and promoting transcriptional activity of the antioxidant defence [ ]. haces et al. [ ] demonstrated that both the l- and d-isoform of bhb and acetoacetate possess direct scavenging effects on ros (bhb effects were specific to hydroxyl radicals). the mechanisms by which ketone bodies possess direct antioxidative effects remain to be int. j. mol. sci. , , of elucidated, but the higher capacity related to bhb was speculated to be related to its hydroxyl group [ ]. another in vitro study in neocortical neurons and isolated mitochondria, showed that a combination of bhb and acetoacetate reduced ros production stimulated by calcium induced glutamate excitotoxicity, and that this effect was due to enhanced nadh oxidation and thus, an increased nad+/nadh ratio [ ]. both the increased nad+/nadh ratio and the bhb itself may stimulate the antioxidant defence system through activation of different transcription factors [ , ]. in rodents fed an ad libitum ketogenic diet, hippocampal nad+/nadh levels increased significantly within the first two days of the diet and remained elevated after weeks of following the diet [ ]. likewise, an acute increase in the cerebral nad+/nadh ratio has been reported in young healthy subjects shortly ( min) after ingesting an mcfa product [ ]. however, it is not known if this observation relates to any changes in antioxidant capacity or clinical effect in humans. not all studies support that ketone bodies improve antioxidant capacity [ ]. oxidative stress may lead to mitochondrial dysfunction, further increasing production of ros [ ]. mitochondrial efficiency can be enhanced by ketone bodies, probably through the expression of uncoupling proteins (ucp) [ ]. experimental studies in rodents have demonstrated that animals fed both a ketogenic diet or a ketone ester upregulate ucp and in the brain [ , ]. neuronal ucps are important for the regulation of ros production by reducing the mitochondrial membrane potential, thus normally leading to lower atp generation [ ]. however, it appears that ucps activate mitochondrial proliferation in neurons and thereby compensate for the lower atp production per mitochondria [ ]. furthermore, several studies indicate that bhb possesses anti-inflammatory effects [ ], where animal models of pd [ ] and ad [ ] have been used to report reductions in microglial activation with ketone administration. hence, these preclinical studies suggest that ketone bodies may support energy metabolism in ways not limited to fuel supply. the theory related to the fuel crisis seen with neurodegenerative disease is summarised in figure , which also demonstrates the proposed protective mechanism of ketone bodies, especially bhb. int. j. mol. sci. , , x for peer review of increased nad+/nadh ratio [ ]. both the increased nad+/nadh ratio and the bhb itself may stimulate the antioxidant defence system through activation of different transcription factors [ , ]. in rodents fed an ad libitum ketogenic diet, hippocampal nad+/nadh levels increased significantly within the first two days of the diet and remained elevated after weeks of following the diet [ ]. likewise, an acute increase in the cerebral nad+/nadh ratio has been reported in young healthy subjects shortly ( min) after ingesting an mcfa product [ ]. however, it is not known if this observation relates to any changes in antioxidant capacity or clinical effect in humans. not all studies support that ketone bodies improve antioxidant capacity [ ]. oxidative stress may lead to mitochondrial dysfunction, further increasing production of ros [ ]. mitochondrial efficiency can be enhanced by ketone bodies, probably through the expression of uncoupling proteins (ucp) [ ]. experimental studies in rodents have demonstrated that animals fed both a ketogenic diet or a ketone ester upregulate ucp and in the brain [ , ]. neuronal ucps are important for the regulation of ros production by reducing the mitochondrial membrane potential, thus normally leading to lower atp generation [ ]. however, it appears that ucps activate mitochondrial proliferation in neurons and thereby compensate for the lower atp production per mitochondria [ ]. furthermore, several studies indicate that bhb possesses anti-inflammatory effects [ ], where animal models of pd [ ] and ad [ ] have been used to report reductions in microglial activation with ketone administration. hence, these preclinical studies suggest that ketone bodies may support energy metabolism in ways not limited to fuel supply. the theory related to the fuel crisis seen with neurodegenerative disease is summarised in figure , which also demonstrates the proposed protective mechanism of ketone bodies, especially bhb. figure . vicious circle of energy crisis in neurodegenerative disease. the proposed effects of beta- hydroxybutyrate (bhb) on disease mechanisms are illustrated in green, demonstrating an inhibition of oxidative stress, neuroinflammation and mitochondrial dysfunction together with a facilitated ketone oxidation, which results in at least a partially restored metabolism. figure . vicious circle of energy crisis in neurodegenerative disease. the proposed effects of beta-hydroxybutyrate (bhb) on disease mechanisms are illustrated in green, demonstrating an inhibition of oxidative stress, neuroinflammation and mitochondrial dysfunction together with a facilitated ketone oxidation, which results in at least a partially restored metabolism. int. j. mol. sci. , , of . the therapeutic role of ketone bodies in neurodegeneration . . ketone bodies and cognition in alzheimer’s disease and related conditions a number of approaches to increase ketone body availability have been applied in elderly individuals and in diseases affecting cognition. these approaches include both acute interventions of bhb infusion [ ] or a single meal/drink of mcfa [ – ], and also long-term treatments with continued mcfa supplementation as an add-on to the regular diet [ – ] or complete conversion to a ketogenic diet [ – ]. a predominance of studies has been conducted in patients with mild cognitive impairment and ad and apply the mcfa supplementation approach to achieve ketonemia. hence, future studies implementing other ketogenic approaches will strengthen the evidence of a ketone-induced cognitive improvement. individuals without cognitive disease: in persons without known cognitive disease but suffering from type diabetes, which is a risk factor for cognitive impairment [ , ], an i.v. infusion of bhb (blood levels of . mm), significantly improved working memory performance when compared to a placebo infusion. however, no change in a global cognitive score was found [ ]. further, in elderly persons without dementia, a single ketogenic meal of mcfa improved performance in several cognitive domains, with improvements correlating to levels of circulating bhb [ ]. consistently, cognitive benefits have been reported in elderly nursing home residents with prolonged treatment durations of mcfa supplementation [ ]. these studies together suggest that individuals without cognitive disease may benefit from a ketogenic intervention. notably, increased age and type diabetes (both characterized by insulin resistance) significantly increase risk of ad, and both have been associated with cerebral glucose hypometabolism [ ]. similar to ad, ketone metabolism does not decline with aging [ ]. individuals with cognitive impairment: in patients with mild cognitive impairment and ad, a single acute dose of mcfa resulted in significant increases in bhb (from . mm to . mm), reger et al. [ ] found improved adas-cog score and paragraph recall in a placebo-controlled cross-over design. subsequent analysis found this to be true for apoe -negative subjects only [ ]. in contrast, a quite similar experiment including twenty japanese patients with mild-to-moderate ad, did not find any acute improvement in any cognitive measure after ingestion of mcfa [ ]. no genotyping was performed in this study, which could explain the absent effect. since an acute cognitive improvement was found in three studies, it could imply that increased energy supply during ketone treatment, partly explains the neuroprotective effect, since other signalling properties of ketone bodies might be expected to require more time. in a non-acute (exposure days) placebo-controlled trial of an oral ketone supplement (ac- ; composed of caprylic acid) in patients with mild to moderate ad, significant improvements in cognitive performance, evaluated by the adas-cog score, were reported [ ]. in this trial, bhb levels increased (two hours after dosing) to an average of ~ . mm after three months intervention, and similar to previous studies, the mitigating effects of the ketone body supplement was limited to apoe negative participants [ ]. likewise, a cross-over study consisting of thirty days mcfa supplementation in ad patients, also resulted in an improvement in the adas-cog-c score in apoe negative patients and not in apoe positive (only three individuals were apoe positive) [ ]. the reason for this genotype-specific effect of ketogenic treatment is yet unknown but has been speculated to be derived from differences in the pathophysiology between apoe positive and negative [ , ]. for instance, mitochondrial function differs between genotypes, being lower in apoe positive individuals, and thus may limit the utilization of ketones. another proposed mechanism, is that the slightly more pronounced insulin resistance in apoe negative individuals, upregulates the expression of mcts, which is elevated in diabetes, allowing for a higher uptake and thus, utilization of ketones [ ]. in agreement with the above studies, fortier et al. [ ] recently published the cognitive outcomes from the benefic trial, a month placebo-controlled trial of mcfa supplementation in patients with mild cognitive impairment (mcfa arm: n = ; placebo arm: n = ). the study found significant int. j. mol. sci. , , of improvements in tests related to memory (free and cued recall), executive function (verbal fluency and trail-making test), and language (boston naming test), which may be related to the improved total energy metabolism in the brain found in the first part of the trial [ ]. the largest trial conducted so far applying a ketogenic intervention was recently published by henderson et al. [ ]. in this study, patients with mild-to-moderate ad were randomized to receive either a new ketogenic formulation (ac- ) or placebo for weeks to assess the safety and efficacy of this compound. results were disappointing with regard to the cognitive evaluations; no effect was found on the adas-cog score compared to placebo for either apoe -positive or negative patients. only modest elevations of ketone levels were seen, which corresponded to less than half of the increase found with previously used compound (ac- ). this level of ketonemia is most likely insufficient to improve cerebral metabolism and further suggests that some increase in ketone body levels is necessary to achieve a cognitive improvement [ ]. diet-induced hyperketonaemia (very low versus high carbohydrate diets) over six weeks was applied by krikorian et al. [ ] in a small sample of patients with mild cognitive impairment resulting in improved verbal memory performance in the low carbohydrate group. in the post-hoc analyses, the improvements were correlated to ketone body levels. no correlation was seen with other metabolic changes such as weight, insulin or glucose levels [ ]. similarly, in a series of studies with a limited number of participants, ketogenic dietary interventions significantly improved cognition in ad or mild cognitive impairment [ , , ]. the potential cognitive benefit from exogenous ketones has not been described in detail. in a single case-study of a subject with early-onset ad ketone ester treatment was initiated, this resulted in improved memory retrieval, mood and performance of daily activities [ ]. overall effects on cognition are shown in figure . int. j. mol. sci. , , x for peer review of and trail-making test), and language (boston naming test), which may be related to the improved total energy metabolism in the brain found in the first part of the trial [ ]. the largest trial conducted so far applying a ketogenic intervention was recently published by henderson et al. [ ]. in this study, patients with mild-to-moderate ad were randomized to receive either a new ketogenic formulation (ac- ) or placebo for weeks to assess the safety and efficacy of this compound. results were disappointing with regard to the cognitive evaluations; no effect was found on the adas-cog score compared to placebo for either apoe -positive or negative patients. only modest elevations of ketone levels were seen, which corresponded to less than half of the increase found with previously used compound (ac- ). this level of ketonemia is most likely insufficient to improve cerebral metabolism and further suggests that some increase in ketone body levels is necessary to achieve a cognitive improvement [ ]. diet-induced hyperketonaemia (very low versus high carbohydrate diets) over six weeks was applied by krikorian et al. [ ] in a small sample of patients with mild cognitive impairment resulting in improved verbal memory performance in the low carbohydrate group. in the post-hoc analyses, the improvements were correlated to ketone body levels. no correlation was seen with other metabolic changes such as weight, insulin or glucose levels [ ]. similarly, in a series of studies with a limited number of participants, ketogenic dietary interventions significantly improved cognition in ad or mild cognitive impairment [ , , ]. the potential cognitive benefit from exogenous ketones has not been described in detail. in a single case-study of a subject with early-onset ad ketone ester treatment was initiated, this resulted in improved memory retrieval, mood and performance of daily activities [ ]. overall effects on cognition are shown in figure . figure . overview of cognitive domains affected by ketogenic interventions in patients with mild cognitive impairment or ad. overall improvements are demonstrated by green arrows. illustration is solely based on studies using a randomized-controlled study design (cross-over or parallel groups). interventions included ketogenic diets [ , ] or supplementation with mcfas [ , – , ] ranging from acute ( min after ingestion) to months in duration and studies include between and participants. apart from cognition, a number of paraclinical features have been studied in neurodegeneration. for example, the notion of disturbed cerebral fuel metabolism in neurodegeneration is far from recent; in , lassen et al. described a decreased cerebral oxygen metabolism in people with “presenile dementia”, a finding corroborated by lying-tunell et al. in [ , ]. in people with milder cognitive complaints, both neth et al. [ ] and nagpal et al. [ ] describe an increased amyloid content and a trend towards a lower tau and a lower neurofilament light level after six weeks on a ketogenic diet. in the first of these studies, pet imaging showed an increase in acetoacetate metabolism with no change in glucose metabolism, whereas in the latter, the changes in figure . overview of cognitive domains affected by ketogenic interventions in patients with mild cognitive impairment or ad. overall improvements are demonstrated by green arrows. illustration is solely based on studies using a randomized-controlled study design (cross-over or parallel groups). interventions included ketogenic diets [ , ] or supplementation with mcfas [ , – , ] ranging from acute ( min after ingestion) to months in duration and studies include between and participants. apart from cognition, a number of paraclinical features have been studied in neurodegeneration. for example, the notion of disturbed cerebral fuel metabolism in neurodegeneration is far from recent; in , lassen et al. described a decreased cerebral oxygen metabolism in people with “presenile dementia”, a finding corroborated by lying-tunell et al. in [ , ]. in people with milder cognitive complaints, both neth et al. [ ] and nagpal et al. [ ] describe an increased amyloid content and a trend towards a lower tau and a lower neurofilament light level after six weeks on a ketogenic diet. in the first of these studies, pet imaging showed an increase in acetoacetate metabolism with no change in glucose metabolism, whereas in the latter, the changes in cerebral spinal fluid markers could be related to ketone-induced changes in the gut microbiome. int. j. mol. sci. , , of similar results were described by fortier et al. [ ] in people with mild cognitive impairment. as for cerebral blood flow, in a study employing days of exposure to caprylidene, a precursor for bhb and acetoacetate, patients with mild ad significantly increased blood flow in several brain regions, with the effects confined to people with no apoe allele [ ]. . . ketone bodies in other neurodegenerative diseases in pd, several animal studies have demonstrated neuroprotective effects of ketosis [ – ]. only a few human studies have been conducted. in a pilot study, five patients were able to prepare a ketogenic diet and adhere to it for weeks, which lead to significant improvement in the unified parkinson’s disease rating scale scores [ ]. further, when compared to a regular diet, a ketogenic diet for months improved the voice handicap index in pd patients [ ]. phillips et al. [ ] randomized patients with pd to weeks of a ketogenic diet versus a low-fat, high-carbohydrate diet. both diet groups significantly improved in motor and non-motor symptoms; however, the ketogenic group showed greater improvements in non-motor symptoms, including cognitive function. in animal models of als, exposure to hyperketonaemia alters clinical and biological manifestations of the disease. a ketogenic diet led to higher motor neuron survival and an improvement in motor function in a sod -g a transgenic als model compared to controls [ ]. the same research group has further demonstrated that supplementation of a precursor of ketone bodies alleviates als-motor impairment together with an increase in mitochondrial oxygen consumption rates in the spinal cord. this suggest that the additional ketones might be used as an alternate substrate for energy metabolism in als animals [ ]. in vivo, bhb exerts dose-dependent neuroprotection, preserving motor function and reducing motor neuron loss [ ]. this motor neuron protection is in agreement with results obtained in animal models with chronic ampa-induced neurodegeneration, showing that bhb infusion prevents motor deficits and paralysis [ ]. for hd, no conclusive effect of ketone bodies in animal models has been described [ – ]. . conclusions and perspectives introducing ketone bodies for the treatment of neurodegenerative diseases may improve neuronal metabolism, which is hampered in such conditions. the observation that some individuals acutely (within h) show improved cognitive function, suggests that ketones immediately provide additional or more efficient energy production in individuals with or at risk of neurodegenerative disease. with long-term ketogenic treatment additional adaptations might take place. preclinical studies suggest that ketone metabolism may be enhanced by persistent ketonemia through increased mct expression and that other adaptations influencing cerebral metabolism occur. however, these effects are most likely not disease modifying, since cognitive improvements disappear when ketogenic treatment is discontinued [ ]. small or medium-sized (n ≤ ) clinical studies, mainly in ad, suggest a positive effect on a few disease outcomes, with most evidence demonstrating improvements in cognitive functions related to memory and language with ketogenic treatments in patients, who are already cognitively impaired. no definitive large-scale clinical studies are currently available. several ways of introducing ketonemia in patients now exist and seem to yield comparative results. however, the most commonly used approach is mcfa supplementation, which—compared to the ketogenic diet and exogenous ketones—induces considerably lower levels of ketonemia. interestingly, some studies have found a correlation between blood levels of ketone bodies and cognitive improvements, implying that treatments which significantly elevate ketone body levels could be more beneficial, but this hypothesis remains to be explored further. apart from ketogenic supplements and ketogenic diets, where implementing their use may be hampered by both availability and adherence problems, new drugs currently used for lowering glucose levels in type diabetes—sodium glucose cotransporter inhibitors (sglt -i)—increase circulating levels of ketone bodies to levels comparable to the ones achieved with mcfa supplements [ ]. indeed, in a pharmaco-epidemiological study, wium-andersen et al. [ ] recently described a decreased risk int. j. mol. sci. , , of of getting a dementia diagnosis while treated with an sglt -i compared to treatment with most other anti-diabetic drugs. applying this drug class to induce mild ketosis could be a possible approach in further studies of neurodegenerative disease. author contributions: all authors contributed to the conceptualization, writing, and editing of this manuscript. all authors have read and agreed to the published version of the manuscript. funding: this research received no external funding. conflicts of interest: the authors declare no conflict of interest. abbreviations acetyl-coa acetyl coenzyme a ad alzheimer’s disease aicar -aminoimidazole- -carboxamide ribonucleotide als amyotrophic lateral sclerosis ampk amp-activated protein kinase bbb blood–brain barrier bhb beta-hydroxybutyrate bhd beta-hydroxybutyrate dehydrogenase glut- glucose transporter type hd huntington disease hmg-coa -hydroxy- -methylglutaryl-coa hmgcs -hydroxy- -methylglutaryl-coa synthase mcfa medium-chain fatty acids mct monocarboxylate transporter pd parkinson’s disease ros reactive oxygen species scot succinyl-coa: -ketoacid coenzyme a transferase sglt -i sodium glucose cotransporter inhibitors tca tricarboxylic acid ucp uncoupling proteins references . rolfe, d.f.; brown, g.c. cellular energy utilization and molecular origin of standard metabolic rate in mammals. physiol. rev. , , – . 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[crossref] [pubmed] publisher’s note: mdpi stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . /j.exger. . . http://dx.doi.org/ . /s - - -y http://dx.doi.org/ . /j.brainres. . . http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . / .wnl. . . http://dx.doi.org/ . /s - - - http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /mds. http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . / - - - http://dx.doi.org/ . /journal.pone. http://dx.doi.org/ . /an http://dx.doi.org/ . /s - - - http://dx.doi.org/ . /journal.pone. http://dx.doi.org/ . /j.physbeh. . . http://dx.doi.org/ . /jhd- http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /dc - http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /eje- - http://www.ncbi.nlm.nih.gov/pubmed/ http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	introduction 	ketone bodies reaching the brain 	the synthesis of ketone bodies in the liver 	ways of increasing the concentration of circulating ketone bodies 	ketone bodies entering the brain via monocarboxylate transporters 	the catabolism of ketone bodies in neuronal and glial cells 	glial–neural compartment mode for ketone body supply to neurones 	the effect of ketone bodies on brain metabolism 	ketone bodies affect brain metabolism in healthy individuals 	hypometabolism in neurodegenerative disease is ameliorated by ketone bodies 	ketone bodies may support metabolism besides being a substrate 	the therapeutic role of ketone bodies in neurodegeneration 	ketone bodies and cognition in alzheimer’s disease and related conditions 	ketone bodies in other neurodegenerative diseases 	conclusions and perspectives 	references energy value stream mapping a tool to develop green manufacturing procedia engineering ( ) – - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of icmem doi: . /j.proeng. . . sciencedirect available online at www.sciencedirect.com * neha verma , e-mail address:nv @gmail.com international conference on manufacturing engineering and materials, icmem , - june , nový smokovec, slovakia energy value stream mapping a tool to develop green manufacturing neha verma , vinay sharma ph.d scholar, department of production engg ,bit, mesra (ranchi)- , india nv @gmail.com, ph professor, department of production engg, bit, mesra (ranchi)- , india vinay @gmail.com, ph abstract- value stream mapping is an effective tool of lean manufacturing to reduce the wastage in any process by segregating value added and non-value added activities. the present work uses the concept of value stream mapping and developed energy value stream mapping to address the non productive energy consuming processes. this paper focuses on achieving green manufacturing as overall productivity which has already reached an acceptable value. the main problem identified is that there is a void when it has been looked for a tool to achieve lean manufacturing along with green manufacturing. it deals with the development of a method that allows a first quick, easy and comprehensive analysis of energy and material flows within the production processes. the paper concludes with discussing improvements in the processes. © the authors. published by elsevier b.v. peer-review under responsibility of [s ]the organizing committee of icmem keywords: vsm, evsm, energy consumption, lean manufacturing, small scale industry. . introduction manufacturing is a leading energy consumer of the world along with being the aspects for prosperity. with rise for the environmental concerns countries are being pressurized to make their industries energy efficient. this has made researcher to analyze means and methods to develop energy efficient machine or reduce the energy consumption in existing methods. improvement in existing setup can be made by eliminating the processes which consumes energy and replace them with energy efficient and less costly methods. in recent, studies have been made towards achieving lean and green manufacturing which minimize wastes. lean techniques are focused on reducing lead time and eliminating wastes in all kinds of forms. green manufacturing is a method for manufacturing that minimizes waste and pollution. its emphasis on reducing parts, rationalizing materials, and reusing components, to help make products more efficient to build. green manufacturing involves not just the u se of environmental design of products, use of environmentally friendly raw materials, but also eco-friendly packing, distribution, and destruction or reuse after the lifetime of the product. authors in the present work have focused on using value stream mapping (vsm), a tool of lean manufacturing, and used it in reducing energy and making the process energy efficient. © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of icmem http://crossmark.crossref.org/dialog/?doi= . /j.proeng. . . &domain=pdf neha verma and vinay sharma / procedia engineering ( ) – . literature review a vsm classifies all the processes into value adding and non-value adding ones. the ultimate goal of vsm is to identify all types of waste (non-value added) in the value stream and to take steps to eliminate them. authors (fawaz & rajgopal, ) state vsm as one of the best tool for lean manufacturing. the authors in their work have summarized the calculation of energy as value adding and non-value adding energy to optimize value streams in a more holistic way. (murugananthan, et al., ) this paper details with the use of the vsm in reducing waste in manufacturing company. the production process path is visualized by mapping the current state value stream mapping .after tracking the entire process, wastage affecting the cycle time has been identified and its causes are analyzed. a future state value stream mapping is developed and improvement ideas are suggested. value stream mapping is proved as a useful technique to minimize the cycle time and increase the productivity. the paper (solding & gullander, ) presents concept using simulation for creating dynamic vsm. creating dynamic value stream maps makes it possible to analyze more complex system than traditional vsms are able to and still visualize the result in a language the lean coordinator recognize. the value stream mapping is presented in a spread sheet that can be altered in the way the teams want. the authors (fawaz & rajgopal, ) identify that lean manufacturing is applied more frequently in discreet manufacturing rather than in the continuous/process sector and they formulate a simulation model which showed the difference between the past and present scenario clearly which is acceptable to the managers who until now are skeptical about the application of lean methods in continuous/process manufacturing. (egon, et al., ), describe a method to extend vsm to an energy value stream mapping method (evsm) by maintaining its original character and its inner logic. also, this paper includes the time and energy input during the transportation processes into the evsm. this paper goes on to show the application of evsm in supply chain management to reduce the energy footprint on a global level. inclusion of transport into evsm not only shows the lead time extending effect but also its non-value adding energy consumption. (keskin, et al., ), in their paper suggest a future oriented energy value stream mapping approach that aims to improve energy efficiency in small and medium sized manufacturing companies. (tyagi, et al., ), in their paper introduces the concept of vsm to the product development process (pdp) stresses on the importance of faster product development for the right edge on the market. the main focus of this article is to exploit lean thinking concepts in order to manage, improve and develop the product faster while improving or at least maintaining the leve l of performance and quality. authors ( chatterjee, et al., ) have first reported the use of energy value stream mapping (evsm) as a tool to analyze the energy consumption in any manufacturing process. the authors in there research work have used the evsm tool to analyze energy consumption in production of biodiesel. (nassehi, et al., ), in their paper, present a framework to validate the introduction of energy consumption in the objectives of process planning for cnc machining. the paper considers the critical aspect of energy efficiency in manufacturing and in particular process planning of products. computer aided process planning (capp) has continued to be developed for over years with its early origins dating back to the s. a good basis for analyzing energy use in machining is through (gutowski, et al., ) mathematical model for direct energy requirement in machining. . : objective of the research work manufacturing of any product in cnc involved following steps in total or partial a. work holding process b. tool holding process c. alignment d. coolant on & off neha verma and vinay sharma / procedia engineering ( ) – e. tool changing f. work piece orientation changing g. tool approach and retracted back h. loading and unloading of work piece/ pallet fixture. i. moving and waiting if total time on machining is considered as % than % of it is the actual time spend on machining. if this % machining time is consider as %, than it is found that % of it is actual machining rest % is used for other process like positioning, gauging etc. (figure. ). figure. machining time breakup a lot of research work has been done to make process green for the time spend on moving and waiting but a less or no work has been reported to make process green during positioning, loading, gauging etc. the time consumed in positioning, loading, gauging etc. is very small but it has been found that during this period the coola nt flow and cutter movements are not stopped in many cases. the present work concentrate analyzing this time to make process green using a new tool called energy value stream methodology (evsm). . energy value stream mapping evsm (energy value stream mapping) is developed based on the standard of value stream methodology. this has been done by adding energy components in addition to the cost in vsm and the same has been analyzed with respect to time. the evsm identifies the level of energy utilize and wastage in each step and hence determines the opportunities for energy conservations. to analyze the possible outcomes of improvement options, future scenarios are also developed using evsm. the suggested model can be used not only for diagnostic purposes but also for energy budgeting and saving measures. a small scale industry has been taken for implementation and validation of the model. the industry selected is an iso - certified unit. due to confidentiality matters the products manufactured by the industry is named as product a, b, c. the product a consists of components out of which component x, y and z are manufactured in-house and the other components are either purchased or outsourced. only component x will be taken for analysis because this component covers the entire shop floor moving through all the machines. . . assumptions the following assumptions are made in order to develop the energy value stream map (evsm) – . component x is the final component and needs no further assembly. . only the machines with high energy consumption are taken up for energy analysis. moving and waiting time ( %) time on machin ing % actual cutting time % positioning, loading, gauging, etc. % figure : machining time breakup neha verma and vinay sharma / procedia engineering ( ) – . energy consumption during transportation between machines are been ignored. . there is no internal loss of energy in the machine by friction; heat etc. and energy used by machining are same as that of power rating of motors. . . process flow the process flow diagram of component x is shown in figure . the component x is produced using all the cnc machines present in the shop floor. the process starts with cutting raw material in the band saw and ends with anodizing operations. t he rod raw material from the store is being cut through the band saw and transferred to cnc- where various processes like facing, rough turning, drilling, boring, and threading are performed. then it is transferred to cnc- where operations like facing, with taper turning, and v drilling are performed. next step includes the transfer of component to vmc- where operations like flash hole, detent and tape-hole takes place. after this it is transferred to vmc- where hinge pin-hole, and locking pin-hole operations are performed. finally the component is transferred to machine shop and anodizing section. the process flow diagram for the component x is shown in figure . figure : process flow diagram of component "x" . current state value stream map the current state value stream map for the process flow diagram (fig ) is being made and is summarized in figure (verma & sharma, ). the standard symbols depicted in fig. are used to make the current state value stream map (fig ). the energy components are added in the current value stream mapping and current energy value stream is developed (fig ). in order to understand the effect of energy future energy value stream map is developed (fig ). figure : symbols used for value stream mapping (egon, et al., ) cutting cnc - cnc - vmc - vmc - machine shop anodizing neha verma and vinay sharma / procedia engineering ( ) – figure : current state value stream mapping for component "x” (verma & sharma, ) neha verma and vinay sharma / procedia engineering ( ) – figure : energy value stream mapping for component "x" neha verma and vinay sharma / procedia engineering ( ) – figure : future state energy value stream mapping neha verma and vinay sharma / procedia engineering ( ) – . results and discussions energy usages are calculated for the above value stream map (fig ) and an energy span are added to the current state map. the energy calculations are done by using the power rating of the motors. the current energy value stream map is shown in figure . the power ratings used for the calculations are stated below – cutting machine : cutting saw motor power – . kw , coolant motor power – . kw cnc - : spindle motor power – kw , coolant motor power – . kw cnc- : spindle motor power – kw , coolant motor power – . kw vmc : spindle motor power – kw , coolant motor power – . kw for calculation of value adding energy and non-value adding energy the cycle time is divided into value added time when cutting is actually taking place and non-value added time when there is no cutting operation performed, i.e. tool change time and bed travel time etc. for coolant, the energy used during cutting are termed as value added energy whereas the continuous coolant flow during air cutting and tool change etc. are termed as non-value added energy. the continuous spindle movement during non-cutting time is also termed as non-value added energy. referring to the current state energy value stream map fig , the total non-value added energy in the energy span per piece of component “x” is. monthly demand of component “x” is units (as per data collected). thus, assuming the demand of component “x” to be same throughout the year than non-value added energy in a year is as per the msme (micro, small and medium enterprise) data of [msme - ] , the total numbers of msme enterprises in india (registered + unregistered) are . lakhs. assuming all the above mentioned small scale industries to be of the same stature as the one taken in the case study, therefore the total energy which can be saved in india alone per year is equivalent to – further the non-value added energy calculated in the present case study is limited to only following operations: . coolant flow when no cutting is taking place. . spindle rotation during air cutting and tool change operation. this is the kind of energy which can be saved in a small scale industry if they are producing only one component. the total energy saving potential is large if small modifications are made in the existing machine in operation in the entire industries worldwide. . future state energy value stream map future energy value stream map for the process is shown in figure . form the future evsm following conclusion are drawn for process improvement- pull type system should be implemented instead of the prevalent push type. this will reduce the excessive inventory being produced which is then associated with high storage costs for the inventory. also, a lot of energy is wasted in producing such excessive inventory and the machines are not used judiciously. neha verma and vinay sharma / procedia engineering ( ) – the sizes of the bins on the floor are not fixed. that is the work in process inventory is not clear at a point of time. the size of bins should be fixed because the first concept of lean manufacturing is make thing visible. energy wasted during the process is very large, small change in the existing setup may lead to a higher energy saving. . conclusion the above results clearly show the kind of cost saving which can be made by small changes in the process flow. thus, now conclude that designing time- and energy- efficient energy value streams mapping become very important in today’s scenario. with the help of this new value stream mapping a lean and green manufacturing system can be developed. this paper recommends the path of reducing the environmental impact and suggests an approach for the implementation of green system for various manufacturing unit. the importance that energy saving holds need not be listed down as the whole world is well aware of it. the direction in which the world is going it may soon land in an energy crisis when the prime focus will not be on saving money or increasing productivity, but it will be finding alternate sources of energy and most of the current machinery will become obsolete. what this study focuses on is how one can save energy today and postpone that energy crisis time as much as possible. the world as known today may not exist in the same form tomorrow. therefore the evsm is and effective tool to identify the area where the energy is wasted and new design of machine tool or modification in existing setup will help to reduce energy wastage. references [ ] chatterjee r, sharma v, mukherjee s .value stream mapping based on energy and cost system for biodiesel production. international journal of sustainable manufacturing. ; pp. - 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[ ] edrawsoft,value stream mapping software. edraw max. [online] available at: http:www.edrawsoft.com/value-added-flow-chart.php . . [ ] egon m, stock t, schillig r . a method to generate energy value streams in production and logestics in respect of time and energy consumption. production engineering research development. ; pp. - . [ ] fawaz a , rajgopal j. analyzing the benefits of lan manufacturing and value stream maping via simulation: a process sector case study. international journal of production economics. ; pp. - . [ ] gutowski t, dahmus j, thiriez a. electrical energy requirements for manufacturing processes. lueven .cirp. ;pp. - . [ ] hines p, rich n. the value stream mapping tools. international journal of operations and production management. ; pp. - . [ ] keskin c, asan u, kayakutlu g. value stream maps for industrial energy efficency. assessment and simulation tools for sustainable energy systems. ; pp. - . [ ] msme, g. o. i., msme annual report. udyog bhavan.new delhi; http://www.msme.gov.in/. . [ ] murugananthan v,govindaraj k., sakthimurugan d.process planning through value stream mapping fondry. international journal of innovative research in science and technology. ; pp. - . [ ] nassehi n, asrai i, & dhokia v. energy efficiency process planning for cnc machining. cirp journal of manufacturing science and technology. ; pp. - . [ ] solding p ,gullander p. concepts for simulation based value stream mapping. ; pp. - . [ ] tyagi s, alok c, xianming c.value stream mapping to reduce the lead-time of product development process. international journal of production economics. ; pp. - . [ ] verma n, sharma v, lean modeling- a case study on sme. international journal for technological research in engineering (ijtre). ; pp. - . research article acupotomy alleviates energy crisis at rat myofascial trigger points yi zhang , ning-yu du, chen chen, tong wang, li-juan wang, xiao-lu shi , shu-ming li, and chang-qing guo school of acupuncture-moxibustion and tuina, beijing university of chinese medicine, beijing , china center for early childhood development, shijiazhuang maternal and child health care hospital, shijiazhuang , china beijing key laboratory of tcm basic research on prevention and treatment of major disease, experimental research center, china academy of chinese medical sciences, beijing , china department of pain medicine, beijing hospital of traditional chinese medicine, capital medical university, beijing , china correspondence should be addressed to yi zhang; zhangyi.acupotomology@gmail.com received november ; accepted january ; published february academic editor: manel santafe copyright © yi zhang et al. *is is an open access article distributed under the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. *e aim of this study was to determine the effects of acupotomy on energy crises in rat trigger points (trps) by measuring mechanical pain thresholds (mpts) and levels of acetylcholinesterase (ache), free sarcoplasmic calcium (ca +), adenosine ′- triphosphate (atp), adenosine ′-monophosphate (amp), substance p (sp), and calcitonin gene-related peptide (cgrp) in rat muscle trp tissue. male sprague dawley rats (n � ) were randomly divided into four groups: control, trp, acupotomy, and lidocaine injection. enzyme-linked immunosorbent assays were used to measure ache, and free sarcoplasmic ca + concen- trations were determined by fluorescent staining with fura- am; high-performance liquid chromatography was used to measure atp and amp, and sp and cgrp were evaluated by immunohistochemistry. compared with the control group, free sarcoplasmic ca +, amp, sp, and cgrp were higher in the model group, while mpt, ache, and atp were lower. treatment with acupotomy or lidocaine injection reduced free sarcoplasmic ca +, sp, and cgrp and increased mpts and ache levels compared with the model group. however, only acupotomy also led to decreased amp and increased atp levels relative to the model group. we conclude that acupotomy can alleviate energy crises at trps. . introduction myofascial pain syndrome (mps) is a group of clinical disorders characterized by chronic pain arising from soft tissue, associated with one or multiple trigger points (trps) [ ]. myofascial trps are irritable points characterized by taut skeletal muscle bands. *ey can cause soft tissue pain that is activated by pressing, pulling, or overuse. trps can con- tribute to local pain, referred pain, and local twitch re- sponses. *ey can also decrease muscle strength, work endurance, and coordination as well as cause other types of muscle dysfunction. trps are also associated with autonomic nerve manifestations, such as hyperhidrosis and arrector pili muscle response. among patients with soft tissue pain, %– % suffer from mps [ ]. although the exact nature of trps is unknown, simons proposed the energy crisis hypothesis, which was subse- quently developed to generate the integrated hypothesis [ , ]. it contends that contributing factors lead to the malfunction of motor endplates and excessive acetylcholine (ach) leaking from the endplates, causing continuous de- polarization of muscle cell membranes and calcium (ca +) release from the sarcoplasmic reticulum, which cannot be reabsorbed. *erefore, the sarcoplasm continually has high ca + concentrations, causing persistent muscle fiber con- tractions and the formation of taut intramuscular bands that can be palpated [ ]. continuous muscle contraction leads to local hypoxia and hypermetabolism, resulting in local energy crises and the release of sensitizing substances such as - hydroxytryptamine, histamine, bradykinin, and substance p hindawi evidence-based complementary and alternative medicine volume , article id , pages https://doi.org/ . / / mailto:zhangyi.acupotomology@gmail.com https://orcid.org/ - - - https://orcid.org/ - - - https://creativecommons.org/licenses/by/ . / https://doi.org/ . / / (sp). *is stimulates nerve endings, causing pain and sympathetic neuronal symptoms [ ]. acupotomy, also referred to as miniscalpel-needle acupuncture, is a fairly recent development in the ancient practice of acupuncture. acupotomy involves a combination of acupuncture needle insertion and surgical incision and is effective for relieving trps [ ]. while trps are common sites for acupotomy, the mechanism underlying the effects of acupotomy on trps remains unclear. in this study, me- chanical pain thresholds (mpts) and levels of acetylcho- linesterase (ache), free sarcoplasmic ca +, adenosine ′- triphosphate (atp), adenosine ′-monophosphate (amp), calcitonin gene-related peptide (cgrp), and sp were evaluated in rat trps, and the effects of acupotomy on these indicators were compared with the effects of local lidocaine injection. *e results provide a theoretical basis for different interventions to treat trps, including needle insertion at ashi points as described in tcm. . materials and methods . . animals. male specific pathogen-free sprague dawley rats (n � , weeks old, weight ± g) were provided by beijing vital river laboratory animal technology co., ltd. (animal batch number: scxk(jing) - ). rats were raised in the animal house at the beijing university of chinese medicine with five rats per cage, free access to feed and water, natural lighting, indoor temperature of °c± °c, humidity of %– %, and regular ultraviolet disinfection. *e rats were randomly divided into groups (n � each; control, trp model, acupotomy, and lidocaine injection) using the random number table method. during the experiment, the rats were treated and handled with strict adherence to the standards set by the ethical and animal research committees, with approval from the national natural science foundation (no. ). . . experimental reagents and equipment. experimental materials included acupotomes ( . × mm; zyhy, bei- jing, china), lidocaine hydrochloride injections ( %; yoo- kon, beijing, china), normal saline (yookon), iodophor (tiangen, kunming, china), and disposable sterile syringes (yuekang, changzhou, china). other reagents used were rat ache enzyme-linked immunosorbent assay (elisa) kit (csb-e r; huamei, wuhan), phosphate-buffered saline (pbs) solution (hyclone, logan, ut, usa), dulbecco’s modified eagle’s medium (dmem; hyclone), krebs-hen- seleit solution (in mmol/l: nacl, . ; nahco , . ; kcl, . ; mgso , . ; kh po , . ; glucose, . ; cacl , . ; naoh to ph . ), fura- am powder (f ; invi- trogen), fura- calcium imaging calibration kit (f ; invitrogen), ′-adenosine triphosphate disodium salt hy- drate (sigma), sodium adenosine ′- monophosphate (sigma), rat sp immunohistochemical kits (ab , gr - ; abcam), and rat cgrp immunohistochemical kits (ab , gr - ; abcam). . . model preparation. *e rats, except those in the control group, were prepared as trp models by applying “blunt striking injury and eccentric exercise” as previously de- scribed [ ]. briefly, the rats were anesthetized with % urethane solution injected into the abdominal cavity ( . ml/ g). rats were then fixed onto a plank under a striker, and the middle of the left vastus medialis was marked as the target. *e striker was allowed to fall freely from a height of cm to hit the marked position. on the second day, the rats were placed on a − ° treadmill set, so that they ran downhill continuously for min, with the speed gradually rising to m/min, once per week, for weeks. after the th week, rats in the control and model groups were examined by electromyography to confirm trp model establishment. . . interventions. rats in the four experimental groups described above were treated as follows: ( ) control, no intervention; ( ) trp model, no intervention after model preparation; ( ) acupotomy, acupotomy was applied week after trp model preparation; and ( ) injection group, li- docaine injections given week after model preparation ( % urethane solution injected into the abdominal cavity at a dosage of . ml/ g, iodophor application to the trp in the vastus medialis, and injection of . ml of % lidocaine into the taut band once a week for weeks). acupotomy intervention was conducted once per week for weeks. *e specific operation conducted at each point was as follows: ( ) insertion of an acupotome into a trp in the vastus medialis to pierce the taut band; ( ) insertion of an acupotome perpendicular to the belly muscle, with the edge of the acupotome parallel to the taut band; and ( ) the acupotome was then withdrawn and the point pressed for s. . . index assessments . . . electromyography. electromyography assessments were performed in the control and model groups. rats were anesthetized by intraperitoneal injection of % urethane ( . ml/ g) and then fixed on a board. *e skin was cut to expose the left vastus medialis, and an electrode ( . mm) was inserted into the tail as a reference electrode. for the control group, an electrode was slowly inserted into the middle of the vastus medialis, and another electrode was inserted longitudinally mm away from the last electrode into the vastus medialis. finally, the wound was sutured. *e same procedure was performed for the trp group, but local twitching was considered confirmation of insertion into the trp. electromyography recordings were performed when the muscle was at rest (z j-mb-ncc ; ncc, shanghai, china). . . . trp mpts. after the last intervention, rats were anesthetized by % urethane. anesthesia induction was confirmed by squeezing their tails using a power of g [ ] to see if it caused stable abdominal muscle contraction. *e mechanical sensitivity of rat trps was assessed using the von evidence-based complementary and alternative medicine frey mechanical pain stimulator (ugo basile, genomio, italy) to stimulate the trp skin area until ipsilateral hind limb movement occurred [ ]. *e mpt was defined as the minimum stimulus intensity that caused the movement of the hind limbs. trp sensitivity was assessed on days , , , , and , next week after the last intervention. for each measurement, mpts were determined three times, with an interval of min between each test, and the mean of the results was calculated. . . . sample collection. samples were collected after be- havioral assessment. rats were deeply anesthetized using % urethane and then fixed on an operating table with the left vastus medialis fully exposed. an experienced physician confirmed the position of the trp in the vastus medialis by lightly pressing the taut band using the thumb or forefinger. to collect the samples, the vastus medialis was divided at the marked trp, the fascia was carefully removed, and muscle tissue samples ( × . cm) were excised. after sample col- lection, rats were sacrificed by anesthesia overdose. . . . ache elisa. tissue samples were placed in μl pbs (ph . ), rapidly minced with ophthalmic scissors, and homogenized using an ultrasonic homogenizer (fs- t; sxsonic, shanghai, china) and vibration table (kj- c; kangjian, jiangsu, china). tissue homogenates were centrifuged with , g at °c for min, and the super- natants were separated. ache levels in the samples were tested by an ache elisa kit according to the manufac- turer’s protocol. optical density (od) was read at nm on a microplate reader (multiskan mk ; *ermo fisher sci- entific, waltham, ma, usa). concentrations were calcu- lated according to a standard curve, using the curveexpert . software (https://www.curveexpert.net/). . . . fluorescent staining to detect free sarcoplasmic ca +. *e basement membrane of isolated muscle tissue was carefully removed to expose the muscle fibers. *en, a cm length of muscle tissue was cut along the direction of the muscle fibers and rinsed with pbs buffer to load with fluorescent dye. fura- am stock solution was prepared by dissolving fura- am powder (f , invitrogen) in % pluronic f dmso solution. *e muscle tissue was in- cubated with fluorescent staining solution (final fura- concentration was . μmol/l in dmem solution) in the dark at the °c temperature. after min loading, replace the fluorescent loading solution by kh solution and incu- bated another min for twice at the °c temperature to remove unloaded fura- am. *e fluorescence-stained samples in kh solution were then placed in mm glass plates, and only the resting free sarcoplasmic ca + in intact skeletal muscle fibers was measured using an andor ixon emccd (andor, belfast, uk) with a x fluorescence ob- jective lens. a sutter dg xenon lamp system (sutter, sacramento, ca, usa) was used as the excitation light source at ± nm and ± nm, separately, with emitted light measured at ± nm. ca + images were collected from three different positions for each sample, and three muscle fibers were analyzed in each image. *e mean value for the muscle fibers was considered the ca + level in the tissue sample. background fluorescence without staining was also measured for each sample. fluorescence intensities at and nm were corrected by background intensity. *e fluorescence intensity ratio was determined using the and nm excitation wavelengths, and tissue ca + concentration was subsequently calculated using the fol- lowing formula [ ]: [ca +] = kd × (r–rmin)/(rmax–r) × sf / sb (in the formula, kd is the effective dissociation constant, r is the fluorescence ratio, sf is the proportionality coef- ficient for free dye measured at wavelength λ , and sb is the proportionality coefficient for ca +-bound dye at λ ). *e values of rmax and rmin were the ratio values measured by fura- calcium imaging calibration kit (f , invitrogen). . . . atp and amp measurement. tissue samples were weighed and added to precooled . mol/l perchloric acid ( μl/mg) and then homogenized in an ultrasonic cell grinder (scientz- e; scientz, zhejiang, china). ho- mogenates were centrifuged at g ( °c, min). *en, μl supernatant and μl perchlorate were added into a mol/l potash-methanol mixture (volume : ), and the mixture was centrifuged at , g ( °c, min). next, a μl aliquot of the supernatant was removed, diluted with μl water, and assessed by high-performance liquid chromatography. *e conditions were as follows: mobile phase, mm nah po (ph . ), % methyl alcohol; detection wavelength, nm; sample size, μl; column temperature, room temperature; sample temperature, °c. . . . immunohistochemical analysis of sp and cgrp. muscle biopsies were fixed in % formalin and embedded in paraffin. after sectioned at μm thickness, sections were dehydrated in xylene, rehydrated in graded alcohol, and then rinsed with pbs. *en, the antigen was retrieved by mi- crowave ( w) in . m citric acid buffer (ph . ) for min, washed with pbs three times, and then placed in the %h o at room temperature for min. *e antibodies were diluted with pbs buffer. slides were incubated ( °c) overnight with rabbit anti-sp ( : ; abcam) or rabbit anti- cgrp ( : ; abcam) and then with the appropriate sec- ondary biotinylated antibody (boster) for min at room temperature. *e slides were then incubated with the avidin- biotinylated enzyme complex and then put into a peroxidase reaction solution containing diaminoaniline. afterward, fresh dab was added. *en, the slides were washed with pbs, counterstained in hematoxylin, blued in running water, dehydrated with gradient alcohol, cleared with xylene, and mounted with neutral gum. areas positive for sp or cgrp in randomly selected fields of vision (original magnification × ) were counted using image-pro plus . (media cy- bernetics, rockville, md, usa). *e resulting data were collected as immunohistochemical staining-positive signal cumulative optical density (iod) values, which represent the evidence-based complementary and alternative medicine https://www.curveexpert.net/ average positive area. *ese iod values were used as quantitative measures of tissue expression levels. . . statistical analysis. data were analyzed using the spss . statistical software (v . ; ibm corp., armonk, ny, usa). for normally distributed data with homogeneous variance, analysis of variance (anova) was used to compare four groups. for non-normally distributed data, the kruskal–wallis test was used. all data are expressed as mean±standard deviation. p< . and p< . were considered to indicate significant and very significant dif- ferences, respectively (figure ). . results . . electromyography of model group. electromyography was recorded at ms/d and μv/d. figure (a) shows a representative typical endplate potential, which turns neg- ative from baseline. figure (b) shows the fibrillation po- tential, which turns positive from baseline and then turns negative. *is suggests the presence of trps in the vastus medialis of the model group rats [ ]. . . acupotomy effect on trp mpts. compared with the control group, the mptof the model group decreased on the st, nd, rd, th, and th days after intervention (p< . , figure ). moreover, compared with the model group, the mpt increased in the acupotomy group on the st, nd, rd, th, and th days after intervention (p< . , figure ). further, relative to the model group, the mpt was higher in the lidocaine injection group on the st, nd, rd, th, and th days after intervention (p< . , figure ). comparisons between the acupotomy and injection groups showed no significant difference in mpts at any time point tested (p> . , figure ). . . acupotomy effect on ache. ache levels were signifi- cantly lower (p< . ) in the model group than the control group (p< . ). however, ache levels in the acupotomy (p< . ) and injection (p< . ) groups were significantly increased compared with the model group (figure , ta- ble ). *ere was no significant difference between the acupotomy and injection groups (p> . , figure , ta- ble ). *ese data show that acupotomy can increase ache levels in trps. . . acupotomy effect on free sarcoplasmic ca +. free sar- coplasmic ca + in the model group was significantly higher than in the control group (p< . ). relative to the model group, free sarcoplasmic ca + in the acupotomy and in- jection groups was decreased significantly (both p< . , figure , table ). *ere was no significant difference be- tween the acupotomy and injection groups (p> . , fig- ure , table ). *ese findings demonstrate that acupotomy can reduce free sarcoplasmic ca + levels in trps. . . acupotomy effect on atp and amp. atp levels in the model group were significantly lower than those in the control group (p< . ). relative to the model group, atp increased significantly in the acupotomy group (p< . , figure , table ); however, there was no significant dif- ference between the model and injection groups (p> . , figure , table ). *ese findings indicate that acupotomy can enhance atp levels in trps. amp levels in the model group were significantly higher than those in the control group (p< . ), but those in the acupotomy group were significantly lower than those in the model group (p< . , figure , table ). again, there was no significant difference between the model and injection groups (p> . , figure , table ). *ese results show that acupotomy can decrease amp levels in trps. . . acupotomy effect on sp and cgrp. in figure , sp expression was yellowish brown in muscle fibers. sp levels were significantly higher in the model group than the control group (p< . ), but they were significantly lower in the acupotomy group than the model group (p< . , figure , table ). furthermore, compared with the model group, sp levels were significantly lower in the injection group (p< . , table ). *ere was no significant difference be- tween the acupotomy and injection groups (p> . , fig- ure , table ). hence, our findings indicate that acupotomy can reduce sp levels in trp muscle tissue. in figure , cgrp expression was yellowish brown in muscle fibers. cgrp levels were significantly higher in the model group than the control group (p< . ), but those in the acupotomy (p< . ) and injection (p< . ) groups were significantly lower than those in the model group. *ere was no significant difference in cgrp content be- tween the acupotomy and injection groups (p> . , fig- ure , table ). *ese results suggest that acupotomy can reduce cgrp content in trp muscle tissue. . discussion *e results of this study demonstrate that the mpt, ache, free sarcoplasmic ca +, atp, amp, sp, and cgrp levels were altered in rats after trp model generation, and acu- potomy improved these effects. other than the changes in atp and amp levels, which were improved by acupotomy but not lidocaine injection, there were no significant dif- ferences between the effects of acupotomy and those of li- docaine injection. . . energy crisis at trigger points. despite several theories, the exact nature of trps remains unknown [ , ]; however, electrophysiological and histological evidence support the integrated hypothesis of the cause of trps [ ], which contends that an abnormal increase in ach causes increased energy consumption in trps. specifically, motor endplates in active trps release excessive ach in the resting state, resulting in continuous depolarization of muscle fibers. *is causes the sarcoplasmic reticulum to release excessive ca + into myoplasm, followed by continuous muscle fiber evidence-based complementary and alternative medicine contraction that consumes excessive energy. inadequate blood flow due to continuous contraction of muscle fibers cannot effectively replenish energy and oxygen. in energy crises, ca + pumps in the sarcoplasmic reticulum fail to reduce the free ca + in myoplasm, aggravating muscle fiber contraction. energy crises increase algogenic substances at local levels, which further perpetuates ach release at motor endplates, creating a vicious circle [ ]. . . ache indicates endplate function. *is neuromuscular junction is responsible for passing nerve impulses to the skeletal muscles, causing muscle contractions. when an action potential reaches the presynaptic terminal of a motor neuron, ach is released into the synaptic space where it binds to nicotinic ach receptors (achrs) on the muscle membrane. binding of ach to an achr depolarizes the muscle fibers. ach can be hydrolyzed by ache, which is the main factor controlling the duration of ach effects. *erefore, ache measurement is often used to indirectly assess ach levels. excessive ach at the endplate, induced by diisopro- pylfluorophosphate, leads to the formation of the contrac- ture trp nodules [ ], while injection of botulinum toxin into trps in new zealand rabbits can prevent ach release into the synaptic space, thus reducing endplate noise levels in myofascial trigger spot regions [ ]. in addition, trp pathogenesis is related to the sympathetic nervous system [ ] through regulation of motor nerve synaptic vesicle release and levels of postsynaptic membrane achr via its effects on the gαi -hdac -myogenin-murf pathway [ ]. in this study, ache levels were decreased in the trp model compared with control and acupotomy or lidocaine increased ache levels. similarly, a previous investigation reported that ach and achr levels were decreased after dry needling at precise trps, but ache was increased [ ]. overall, the evidence suggests that acupotomy or dry needle treatment may affect trps through regulation of ache levels in neuromuscular junctions. in addition to inactivating ach, ache also promotes neuromuscular junction survival [ ]. in addition to control group model group acupotomy group injection group model preparation acupotomy injection electromyo graphy trp mpts samplecollection ache free sarcoplasmic ca + atp and amp sp and cgrp st– th week statistical analysis th week – th week th week and beyond th week experimental flow chart figure : *e flow chart shows procedures applied to the animals in timeline. model preparation was in the st– th week. electro- myography detection was in the th week. acupotomy and injection were conducted in the – th week. mpt was detected in the th week. sample collection and other tests were in the th week and beyond. μv/d ms/d (a) μv/d ms/d (b) figure : (a) *e typical endplate potential, which turns negative from baseline. (b) *e fibrillation potential, which is positive from baseline and then turns negative. *e scanning speed and sensitivity are ms/d and μv/d, respectively. evidence-based complementary and alternative medicine reflecting the functional state of motor neurons [ ], ache activity can also indicate endplate degeneration and re- generation [ , ]. ache activity is markedly decreased in denervated skeletal muscle, and the presence of ache can be considered a marker of nerve fiber regeneration. hence, the decrease in ache in trps may indicate that trps are as- sociated with changes in nerve or endplate function. indeed, neuroaxonal degeneration and neuromuscular transmission are disordered in trp-containing muscles [ ]. in addition, the type of muscle excitation can also regulate ache activity in the motor endplate, suggesting that the type of synaptic transmission can also regulate ache [ ]. how continuous contraction of muscle fibers at trps is related to decreased ache levels warrants further study. . . two possible reasons for regulating free sarcoplasmic ca +. ca + is a chemical signal that can communicate messages within cells [ ]. originating from motor end- plates at myofascial trps, spontaneous electrical activity (sea) can reflect muscle fiber excitability, depending on trp sensitivity [ ]. decreased ache activity increases the amplitude of miniature excitatory postsynaptic currents, prolonging their attenuation time and causing sustained achr activation that induces a ca + influx [ ]. increases and decreases in free sarcoplasmic ca + directly influence skeletal muscle fiber contraction and relaxation, and one important characteristic of trps is their continuous contraction that causes taut band formation. *e ca + channel blocker ve- rapamil can effectively inhibit sea in myofascial trigger spots in rabbit biceps femoris muscles [ ]. verapamil prevents ca + influx through voltage-dependent ca + channels on the plasma membrane, and it removes the inhibition of sodium (na+) pumps caused by increased ca + loads, thereby re- ducing intracellular ca + and ensuring normal physiological cell function. *is fully shows that intracellular ca + content can have a significant impact on the trigger point. *is investigation provides direct proof that free sar- coplasmic ca + concentrations in the model group were significantly higher than those in the control group. fur- thermore, acupotomy effectively reduced free sarcoplasmic ca + in trp muscle cells. *e reason why acupotomy re- duces free sarcoplasmic ca + requires further study, but it may be associated with changes in ache and ach and/or it may be related to transient muscle cell ca + levels. firstly, ach release is related with muscle spindle. stecco et al. [ ] believe that if the fascia outside the muscle fiber is denser, it will hinder the shortening of the muscle spindle and even produce a chronic stretch on the muscle spindle, thus causing the continuous excitement of the muscle spindle. *is explains the increased ach from endplates at the trigger point and the continued muscle fibers contraction. acupotomy or dry needling may reduce the excitability of muscle spindles by reducing fascia tension and ultimately reducing the ach release and in- tracellular ca +. secondly, na+-ca + exchanger deserves attention. *e na+-ca + exchanger ncx is an atp-independent bidi- rectional transporter with two working modes. hypoxia leads to decreased na+/potassium (k+)-atpase activity and increased intracellular na+ concentrations, causing ncx- mediated exchange of ca + into cells and consequent ca + overload and damage. in a study of the effects of acu- puncture on ca + in skeletal muscle cells, zhuqing et al. inferred that local acupuncture for delayed onset muscle soreness may affect ncx function, thereby inhibiting cy- toplasmic ca + overload [ ]. ∗ # control model acupotomy injection figure : ache concentrations (pg/mg) in each group (control, model, acupotomy, and injection; n � per group). ∗p< . compared with the control group, #p< . compared with the model group, Δp< . compared with the model group, and ▲p> . compared with the acupotomy group. *e error bars represent the standard deviations. table : changes in ache levels after acupotomy (x ± s). groups n ache (pg/mg) control . ± . model . ± . ∗ acupotomy . ± . # injection . ± . ▲Δ versus control group: p∗< . ; versus model group: p#< . ; versus model group: pΔ< . ; versus acupotomy group: p▲> . . mtrps vf threshold (g) of four groups control model acupotomy injection v f th re sh ol d (g ) time (day) Δ Δ Δ Δ Δ figure : mpt changes (g) in each group (control, model, acu- potomy, and injection; n � per group) determined by the von frey mechanical pain stimulator test. ■p< . versus the model group. Δp< . versus the model group. ◆p< . versus the model group. *e error bars represent standard deviations. evidence-based complementary and alternative medicine . . atp and adp indicate energy supply. *e persistent contraction of muscle fiber trps increases local energy consumption and restricts blood circulation. atp produced by oxidative phosphorylation is the direct source of energy for muscle contraction and sarcoplasmic reticulum ca + reabsorption. a lack of atp in the muscle reduces its ability to function, including both contraction and relaxation. adenosine ′-diphosphate (adp) and amp are degradation products of atp and have important functions in fatigue [ , ]. in this study, atp levels were lower in the model group than control group, which is consistent with the integrated hypothesis. furthermore, this decrease was at- tenuated following acupotomy. *is effect may be caused by improved blood circulation in trps in response to decreased free sarcoplasmic ca +. . . cgrp enhances ach effect at motor endplate. continuous contraction leads to local ischemia and hypoxia in trps, which can cause the tissue to release vasoactive substances that act on nociceptors, leading to nerve sensitization, pain, and ach release from nerve endings [ ]. using microanalytical techniques, shah et al. found that concentrations of protons, bradykinin, cgrp, sp, tumor necrosis factor-alpha, interleukin- beta, serotonin, and norepinephrine were significantly higher in active trps [ , , ]. muscle pain is associated with muscle nociceptor activation by a variety of endogenous substances including neuropeptides and inflammatory mediators. sp and cgrp can cause plasma extravasation, inflammation, and nociceptive effects [ ]. cgrp exists in the ends of ɑ motor neurons and promotes ach release into the synaptic cleft [ ]. importantly, in relation to trps, cgrp increases the number of achrs and inhibits ache activity at motor endplate [ , ], thereby enhancing the effect of ach at the motor endplate. gerwin and shah hypothesized that cgrp enhances the motor endplate re- sponse to ach by increasing the activity and synthesis of achrs [ ]. in this investigation, we found significantly ele- vated levels of sp and cgrp in tissue from trps. furthermore, both sp and cgrp were significantly lower in the acupotomy group than the model group, which is consistent with the common observation of decreased pain after trp treatment. acupuncture increases local nitric oxide and microcirculation [ , ], so local microcirculation in trps should be evaluated before and after needling to determine whether it dilutes algogenic substances. in figures and , images of acupotomy and injection groups show lymphocyte infiltration and destruction of the fiber order, which may indicate the healing process of in- juries. because both acupotomy and injection are invasive, is the healing process of injuries related to treatment effect? table : changes in atp/amp levels after acupotomy (x ± s). groups n atp (ng/mg) amp (ng/mg) control . ± . . ± . model . ± . ∗ . ± . ∗∗ acupotomy . ± . # . ± . ## injection . ± . Δ . ± . ΔΔ versus control group: p∗< . ; versus model group: p#< . ; versus model group: pΔ> . ; versus control group: p∗∗< . ; versus model group: p##< . ; versus model group: pΔΔ> . . ∗ ∗∗ # ## Δ ΔΔ atp ng/mg amp ng/mg a p/ a m p (n g/ m g) control model acupotomy injection figure : atp and amp levels (ng/mg) in each group (control, model, acupotomy, and injection; n � per group). ∗p< . for atp levels compared with the control group, #p< . for atp levels compared with the model group, Δp> . for atp levels compared with the model group, ∗∗p< . for amp levels compared with the control group, ##p< . for amp levels compared with the model group, and ΔΔp> . for amp levels compared with the model group. *e error bars represent the standard deviations. ∗ # control model acupotomy injection figure : free sarcoplasmic ca + concentrations (nmol/l) in each group (control, model, acupotomy, and injection; n � per group). ∗p< . compared with the control group, #p< . compared with the model group, Δp< . compared with the model group, and▲p> . compared with the acupotomy group. *e error bars represent the standard deviations. table : changes in free sarcoplasmic ca + levels after acupotomy (x± s). groups n free sarcoplasmic ca + (nmol/l) control . ± . model . ± . ∗ acupotomy . ± . # injection . ± . ▲Δ versus control group: p∗< . ; versus model group: p#< . ; versus model group: pΔ< . ; versus acupotomy group: p▲> . . evidence-based complementary and alternative medicine stecco et al. [ ] believe that the increased fascia density outside the muscle fiber may excite muscle spindle, causing increased ach from endplates and continued contraction. acupotomy or dry/wet needling may reduce the excitability of muscle spindles by changing the inner environment around the fibers. . . relationship between trp and ashi points. herman et al. proposed the concept of trps in [ ]. since accepting the concept of trps, some chinese scholars believe that trps and tcm ashi points exhibit considerable overlap in their positions, needling sensation, and indications [ ]. when investigations into trps began, tcm practitioners believed that trps can be considered typical representative ashi points. but a contrary opinion is that the overlap of a number of pain points does not change that basic dif- ference between acupoints and trps. acupoints and trps are derived from vastly different concepts [ ]. no matter the two concepts have similarities or differences in es- sence, it will be an hint to promote the reseach of ashi points in tcm. although ashi points have been under- stood by practitioners of tcm for several centuries and various acupuncture methods have been applied in tcm to treat ashi points, deep research into ashi points has been lacking. (a) (b) (c) (d) ∗ # control model acupotomy injection sp iod (e) figure : immunohistochemistry for sp (light microscopy, × ). sp expression was yellowish brown in muscle fibers. sp and cgrp levels by group (control, model, acupotomy, and injection; n � per group). ∗p< . for sp compared with the control group; #p< . for sp compared with the model group; Δp< . for sp compared with the model group;▲p> . for sp compared with the acupotomy group. *e error bars represent the standard deviations. (a) control group. (b) model group. (c) acupotomy group. (d) injection group. (e) sp iod. table : changes in sp/cgrp iod after acupotomy (x ± s). groups n sp cgrp control ± . . ± . model . ± . ∗ . ± . ∗∗ acupotomy . ± . # . ± . ## injection . ± . Δ . ± . ΔΔ versus control group: p∗< . ; versus model group: p#< . ; versus model group: pΔ< . ; versus acupotomy group: p▲> . ; versus control group: p∗∗< . ; versus model group: p##< . ; versus model group: pΔΔ< . ; versus acupotomy group: p▲▲> . . evidence-based complementary and alternative medicine . conclusion developed from ancient acupuncture techniques, acupot- omy is similar to dry needling; both require accurate in- sertion of needles into local trps, and they may also work via similar mechanisms. *e observations from our study support the hypothesis that energy crises affect trp muscle fibers. furthermore, our data demonstrate that acupotomy can influence trp mpts and levels of ache, free sarco- plasmic ca +, atp, amp, sp, and cgrp. its effects were similar to local lidocaine injection, except only acupotomy affected atp and amp levels. it is indicated that acupotomy has effect on trigger point pathophysiology, which is dif- ferent from acupuncture analgesia. future research will focus on the mechanism by which acupotomy resolves energy crises in trps, peripheric or central? *e general understanding of acupuncture mechanism is that the mechanical signals generated by needle insertion are converted into nerve signals through the acupoint and transmitted to the central nervous system and on to the efferent system and effector organs via the neuro-endocrine- immune system [ ]. further, acupuncture may have pe- ripheral effects, independent of overall neurohumoral reg- ulation [ , ]. zhuqing et al. [ ] found that local acupuncture is effective in delaying muscle soreness onset because it adjusts the catabolism and anabolism of muscle contractile proteins. *is differs from the mechanism in- volved in acupuncture analgesia. *e same effect was ob- served in isolated semitendinosus muscle experiments, suggesting that acupuncture may have a peripheral mech- anism independent of overall neurohumoral regulation. for visceral disorders, it is necessary for acupuncture to work via (a) (b) (c) (d) ∗ # control model acupotomy injection cgrp iod (e) figure : immunohistochemistry for cgrp (light microscopy, × ). cgrp expression was yellowish brown in muscle fibers. cgrp levels were significantly higher in the model group than the control (p< . ), acupotomy (p< . ), and injection (p< . ) groups. *ere was no significant difference in cgrp content between the acupotomy and injection groups (p> . ). sp and cgrp levels by group (control, model, acupotomy, and injection; n � per group). ∗p< . for cgrp compared with the control group; #p< . for cgrp compared with the model group;▲p> . for cgrp compared with the acupotomy group;Δp< . for cgrp compared with the model group. *e error bars represent the standard deviations. (a) control group. (b) model group. (c) acupotomy group. (d) injection group. (e) cgrp iod. evidence-based complementary and alternative medicine the neuro-endocrine-immune system because the viscera cannot be needled directly. but for myofascial lesions, it is different because muscular fasciae can be needled directly. for myofascial disorder, what will happen when it is needled directly? acupuncture was shown to trigger a local increase in adenosine in human subjects [ , ] and to increase local microcirculation [ , ]. it is still controversial whether a trigger point is a central or peripheral phenomenon [ ]. accurate positioning at trps is an important requirement for both acupotomy and dry needling, suggesting that the effects of these procedures may have similar underlying peripheral mechanisms; however, a review reported that due to the scarcity of reliable studies, the current evidence on the local effects of acupuncture is insufficient to draw reliable conclusions [ ]. additional investigations are needed to verify the local effects of acupuncture. *e limitation of this study is that only one method was used to test each variable; therefore, our data lack verifi- cation with multiple experimental methods. and several anesthesia procedures during the experiment may influence the results. data availability *e data used to support the findings of this study are available from the corresponding author upon request. conflicts of interest *e authors declare that there are no conflicts of interest regarding the publication of this paper. acknowledgments *e research program was funded by the national natural science foundation of china (no. ). references [ ] s. money, “pathophysiology of trigger points in myofascial pain syndrome,” journal of pain & palliative care pharma- cotherapy, vol. , no. , pp. - , . 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[ ] s.-y. kim, s. min, h. lee et al., “changes of local blood flow in response to acupuncture stimulation: a systematic review,” evidence-based complementary and alternative medicine, vol. , article id , pages, . evidence-based complementary and alternative medicine book reviews © brian meeks, | doi: . / - this is an open access article distributed under the terms of the creative commons attribution-noncommercial . unported (cc-by-nc . ) license. f.s.j. ledgister michael manley and jamaican democracy, – : the word is love. lanham md: lexington books, . xii + pp. (cloth us$ . ) fragano ledgister’s michael manley and jamaican democracy is a welcome foray into what one hopes will become a new wave of literature reflecting on themanleyregimeofthe sandtheseveresocialandpoliticalconflicts that erupted when it sought to reform the jamaican class and racial social struc- tures inheritedfromthecolonialperiod.asthetitlesuggests,ledgister focuses less on manley’s international dimensions (for a new international economic order and against apartheid, for instance) and more on his personal philoso- phyandthepoliticsofhisdeclared“democraticsocialist”government.thishe doesmainlybyreviewingmanley’sbooks(the politics of change, a voice at the workplace, and struggle in the periphery) and critiquing the respective roles of manley’snemesisandsuccessorasprimeminister,edwardseaga,andtheerst- while leader of the party’s left wing, d.k. duncan. the results provide a critical sketch of the country’s challenges in addressing urgent demands to improve thewelfareofthepoorinthefaceofadverselyshiftingtermsoftradeandinthe teethof the game-changingenergycrisis.ledgisteralsocapturesverywell the essence of manley’s philosophy, with its peculiar hybridity—advocating a radical participatory democracy by maintaining liberal, parliamentary forms and legislating for greater social equality, while at the same time operating within an essentially capitalist framework. it is a useful sketch of the man and histurbulenttimes,thoughquiteevidently, thereismuchmorethatcouldhave been said. in examining the electoral defeat of the regime in the violent elections of , ledgister steers clear of discussing manley’s charges of external destabi- lization.manleyhimself inhis retrospective struggle in the periphery isexplicit as to the nature of foreign intervention, but here it is largely missing. even on the local front, ledgister avoids serious analysis of the burning questions of causality and which parties are to be blamed for the initiation and escalation of violence before and during that decade. there is a dark lacuna in studies of jamaican politics in which references to who did what and when is either absentaltogetherorpaperedoverthroughtheanodynenotionthat“bothsides are to be blamed.” ledgister, despite devoting chapters to both former jlp prime minister seaga and sometime pnp general secretary d.k. duncan— certainly perceived as among the leading protagonists—fails to shed light on this critical dimension, so central to a fuller reading of manley and his legacy. thereareafewotherquestionablecallsandelisions. inchapter ,anexplo- ration of manley’s a voice at the workplace and his early stewardship of the downloaded from brill.com / / : : am via free access http://creativecommons.org/licenses/by-nc/ . / http://creativecommons.org/licenses/by-nc/ . / book reviews new west indian guide ( ) – national worker’s union (nwu), ledgister reports on manley’s involvement in the union without reference to its historical role as the alternative to the left- dominated trades union congress (tuc). the nwu emerged to shore up pnp supportamongtheorganizedworkingclassafter thepnp’s leftwing,whobuilt thetuc,hadbeenexpelledfromthepartyunderseverecoldwarpressure.this historyandmanley’sroleinunderminingtheinfluenceofthetuciswellestab- lished and the irony is that the very person who consolidated the nwu—and by affiliation, confirmed the pnp as a moderate party, acceptable to western cold war sensibilities—would, some two decades later, re-emerge as a major gadfly and irritant to u.s. interests as “joshua,” the democratic socialist hero of the people. this entire metamorphosis is unexplored. the d.k. duncan chapter is particularly unsatisfying. ledgister introduces duncan as the left-wing counterpoint to manley’s more moderate version of democratic socialism. but instead of focusing in any depth on the substance of duncan’s history as a former black power advocate and carefully tracing his points of agreement and disagreement with both manley and the more radi- cal elements within and outside the pnp, ledgister hinges the chapter on the strangeanecdotesurroundingduncan’scontroversialstatementattheopening of the jamaica german automotive school. duncan, then minister of mobi- lization, is purported to have said that the school was too sanitized, imply- ing, depending on one’s interpretation, that he was either condescending to jamaicanworkingpeople,hostileandunmannerlytothegermangovernment, orsimplygauche.despitetherelativeobscurityof theincident, thiscouldhave been used to launch a far more textured investigation of duncan’s ideological positions, but the chapter ends with the rather tentative conclusion that dun- can stood for a “proletarian democracy” (which, however, is never explored in any detail). ledgister has managed to put together a compact and accessible reintro- duction to one of the most significant postcolonial leaders and his protean attempts to tear the country away from its colonial moorings. at the same time,amoresubstantialanalysis stillneedstobeundertakeninorder tobetter understand manley and take us beyond this not-insignificant effort. brian meeks africana studies department, brown university, providence ri , u.s.a. brian_meeks@brown.edu downloaded from brill.com / / : : am via free access mailto:brian_meeks@brown.edu int. j. med. sci. , vol. http://www.medsci.org iinntteerrnnaattiioonnaall jjoouurrnnaall ooff mmeeddiiccaall sscciieenncceess ; ( ): - . doi: . /ijms. short research communication metabolome analysis of erythrocytes from patients with chronic hepatitis c reveals the etiology of ribavirin- induced hemolysis tetsuru karasawa , takafumi saito , yoshiyuki ueno , masahiro sugimoto , tomoyoshi soga . department of gastroenterology, yamagata university school of medicine, yamagata, yamagata - ; . institute for advanced biosciences, keio university, tsuruoka, yamagata - , japan.  corresponding author: takafumi saito, m.d., department of gastroenterology, yamagata university school of medicine, - - iida-nishi, yamagata, yamagata - , yamagata, japan tel: + - - - fax: + - - - email: tasaitoh@med.id.yamagata-u.ac.jp © ivyspring international publisher. this is an open-access article distributed under the terms of the creative commons license (http://creativecommons.org/ licenses/by-nc-nd/ . /). reproduction is permitted for personal, noncommercial use, provided that the article is in whole, unmodified, and properly cited. received: . . ; accepted: . . ; published: . . abstract ribavirin is one of the major agents used in combination therapy with interferon for chronic hepatitis c, but is often associated with hemolytic anemia as a serious adverse event. employing metabolome analysis, we demonstrated that the concentrations of intermediate metabolites produced by glycolysis and the pentose phosphate cycle in patients’ erythrocytes were significantly decreased after administration of ribavirin. our findings suggest that hemolysis associated with ribavirin is triggered by an energy crisis and consequent oxidative stress, thus having implications for the prevention of such hemolysis. key words: hcv, ribavirin, anemia, metabolome, glycolysis, pentose phosphate cycle. introduction hepatitis c virus (hcv) is the major causative pathogen of chronic liver diseases with a risk of pro- gression to cirrhosis and hepatocellular carcinoma. currently, ribavirin is one of the major agents used in combination therapy with interferon for chronic hep- atitis c. during this treatment, however, patients sometimes suffer ribavirin-induced hemolytic anemia as an adverse event, necessitating discontinuation of the therapy or reduction of the dosage of anti-viral agents ( , ). the mechanism of the hemolysis induced by ribavirin has not been clearly determined, but oxida- tive stress and subsequent membrane fragility of erythrocytes have been suggested to play an im- portant role ( , ). after administration, ribavirin is converted to its phosphorylated form within the cell using adenosine triphosphate (atp). however, phosphorylated ribavirin is not converted back to the dephosphorylated form because erythrocytes lack the enzymes necessary for dephosphorylation. thus, the level of atp in cells is reduced as a result of ribavirin phosphorylation ( , ). the metabolic system in erythrocytes consists of glycolysis and the pentose phosphate cycle, for which atp is essential. the pentose phosphate cycle begins with glu- cose- -phosphate (g p), which is the first intermedi- ate metabolite produced by glycolysis, and thus it interacts with glycolysis closely. it has been hypothe- sized that deficiency of atp causes impairment of the glycolytic system, thus triggering an energy crisis within erythrocytes, and inducing oxidative stress, leading to membrane fragility through impairment of the pentose phosphate cycle. in the present study, to investigate changes in the intermediate metabolites of glycolysis and the pentose phosphate cycle in erythrocytes, we carried out the metabolomics analysis of erythrocytes from patients with chronic hepatitis c, who had received antiviral therapy with pegylated interferon plus rib- avirin. it was anticipated that this approach would ivyspring international publisher int. j. med. sci. , vol. http://www.medsci.org help to clarify the mechanism responsible for ribavi- rin-induced hemolysis. methods eight patients with chronic hepatitis c ( men and women, aged . ± . yr, mean±standard de- viation) were treated with pegylated interferon plus ribavirin in accordance with the japanese standard guideline for treatment of chronic hepatitis c ( ). erythrocytes were collected from the patients before and one week after the start of treatment, separated from whole blood by centrifugation, and resuspended in normal saline solution at a concentration of × /μl. for disruption of the erythrocyte membranes, μm methanol solution was added to μl of erythrocyte suspension. the samples were dissolved in μm -aminopyrrolidine and trimesate. the levels of intermediate metabolites in erythrocytes were measured by capillary electrophore- sis-time-of-flight mass spectrometry (ce-tofms) as reported previously ( - ). informed consent was ob- tained from all patients, and the study was approved by the institutional ethics committee. wilcoxon matched-pairs signed rank test was used for statistical analysis, and differences at p < . were considered to be significant. results and discussion hemolytic anemia induced by ribavirin is one of the serious adverse events associated with therapy for chronic hepatitis c ( , ). the erythrocyte count ob- served in this study showed a significant reduction at weeks after the start of ribavirin administration ( . ± . × /μl vs. . ± . × /μl : pretreat- ment vs. weeks after treatment, mean±standard de- viation, p= . ). the drop in the erythrocyte count progressed and became . ± . × /μl at weeks after the start of ribavirin administration. alt- hough the mechanism of this hemolysis has not been precisely clarified, a reduction of atp due to ribavirin phosphorylation has been suggested ( ). a recent study showed that ribavirin-induced anemia is pri- marily due to the effect of the drug on guanosine tri- phosphate, consequently leading to a reduction of atp in erythrocytes ( ). to clarify this mechanism, we focused on the levels of intermediate metabolites of glycolysis and the pentose phosphate cycle in erythrocytes. the changes in the levels of intermediate metab- olites belonging to the glycolytic system and the pentose phosphate cycle in erythrocytes between samples collected before and after ribavirin admin- istration are shown in table . as ribavirin was taken up by erythrocytes, atp was consumed for its phos- phorylation, and as erythrocytes lack the enzymes necessary for ribavirin dephosphorylation, atp defi- ciency progressed and eventually inhibited the gly- colytic system. here we found that the levels of the intermediate metabolites of glycolysis in erythrocytes, including g p, fructose- -phosphate, , -diphos- phoglyceric acid and -phosphoglyceric acid, were significantly lower one week after ribavirin admin- istration than before the start of treatment. this sug- gested that the energy metabolism of erythrocytes had been impaired by ribavirin. table . levels of intermediate metabolites for glycolytic system and pentose phosphate cycle in erythrocytes of patients receiving ribavirin (fmol/cell). int. j. med. sci. , vol. http://www.medsci.org g p is the key metabolite that is central to both glycolysis and the pentose phosphate cycle in eryth- rocytes. g p is metabolized to -phosphogluconic acid, d-ribose- -phosphate and d-sedoheptulose- - phosphate to supply nicotinamide adenine dinucleo- tide phosphate (nadph) for the pentose phosphate cycle. the levels of these metabolites in patients’ erythrocytes were all reduced after ribavirin admin- istration, among which that of d-ribose- -phosphate became significantly lower. this indicated that the decrease in the level of g p influenced the activity of the pentose phosphate cycle and caused a decrease of nadph. nadph has an important role in the reduc- tion of glutathione (gsh) in concert with glutathione reductase. thus it was suggested that the decrease of nadph resulting from impairment of the pentose phosphate cycle led to a decrease in the concentration of reduced gsh, consequently increasing the degree of oxidative stress in erythrocytes. in fact, a previous study has shown that ribavirin treatment causes a significant increase of malondialdehyde and methe- moglobin in erythrocytes, both being typical products of oxidative damage ( ). taken together, the data suggest that two major events in erythrocytes – an energy crisis due to atp deficiency in the glycolytic system and consequent oxidative stress due to im- pairment of the pentose phosphate cycle – are closely related to the occurrence of hemolysis associated with ribavirin. the single nucleotide polymorphisms (snps) of inosine triphosphatase (itpa) gene are shown to be strongly associated with ribavirin-induced hemolytic anemia in chronic hepatitis c ( ). further studies are needed to investigate a relation between snps of itpa gene and levels of intermediate metabolites for glycolytic system and pentose phosphate cycle in a larger cohort of patients. in the treatment of chronic hepatitis c, adequate doses of ribavirin are closely associated with viral clearance, and prevention of both viral breakthrough and emergence of resistant variants ( ). for achieving the maximum effect of an- tiviral therapy, strategies for anemia management during ribavirin administration are essential. the re- sults of this study suggest that some form of medica- tion strategy for both the energy crisis and oxidative stress caused by ribavirin may be important for pre- vention of erythrocyte hemolysis. abbreviations hcv: hepatitis c virus; atp: adenosine tri- phosphate; g p: glucose- -phosphate; ce-tofms: capillary electrophoresis-time-of-flight mass spec- trometry; nadph: nicotinamide adenine dinucleo- tide phosphate; gsh: glutathione; snps: single nu- cleotide polymorphisms; itpa: inosine triphospha- tase. acknowledgement we thank prof. dr. sumio kawata for valuable advises on this work. this study was supported in part by grants from japan science and technology agency, and also in part by grants from the ministry of health, labor and welfare of japan. competing interests the authors have declared that no competing interest exists. references . hynicka lm, heil el. anemia management in patients with chronic viral hepatitis c. ann pharmacother. ; : - . . jacobson im, kowdley kv, kwo py. anemia management in the era of triple combination therapy for chronic hcv. gastroenterol hepatol (n y). ; ( suppl ) : - . . grattagliano i, russmann s, palmieri vo, et al. glutathione peroxidase, thioredoxin, and membrane protein changes in erythrocytes predict ribavirin-induced anemia. clin pharmacol ther ; : - . . de franceschi l, fattovich g, turrini f, et al. hemolytic anemia induced by ribavirin therapy in patients with chronic hepatitis c virus infection: role of membrane oxidative damage. hepatology ; : - . . page t, connor jd. the metabolism of ribavirin in erythrocytes and nucleated cells. int j biochem ; : - . . editors of the drafting committee for hepatitis management guide- lines: the japan society of hepatology. guidelines for the management of hepatitis c virus infection. first edition, may , the japan society of hepatology. hepatol res ; : - . . soga t, baran r, suematsu m, et al. differential metabolomics reveals ophthalmic acid as an oxidative stress biomarker indicating hepatic glutathione consumption. j biol chem ; : - . . shintani t, iwabuchi t, soga t, et al. cystathionine beta-synthase as a carbon monoxide-sensitive regulator of bile excretion. hepatology ; : - . . soga t, sugimoto m, honma m, et al. serum metabolomics reveals γ-glutamyl dipeptides as biomarkers for discrimination among different forms of liver disease. j hepatol ; : - . lau jy, tam rc, liang tj, et al. mechanism of action of ribavirin in the combination treatment of chronic hcv infection. hepatology ; : - . . hitomi y, cirulli et, fellay j, et al. inosine triphosphate protects against ribavirin-induced adenosine triphosphate loss by adenylosuccinate synthase function. gastroenterology ; : - . . fellay j, thompson aj, ge d, et al. itpa gene variants protect against anaemia in patients treated for chronic hepatitis c. nature ; : - . a look into liver mitochondrial dysfunction as a hallmark in progression of brain energy crisis and development of neurologic symptoms in hepatic encephalopathy journal of clinical medicine article a look into liver mitochondrial dysfunction as a hallmark in progression of brain energy crisis and development of neurologic symptoms in hepatic encephalopathy elena kosenko ,* , lyudmila tikhonova , gubidat alilova and carmina montoliu , institute of theoretical and experimental biophysics of russian academy of sciences, pushchino, russia; ljudasik @rambler.ru (l.t.); hells @yandex.ru (g.a.) hospital clinico research foundation, incliva health research institute, valencia, spain; carmina.montoliu@uv.es pathology department, faculty of medicine, university of valencia, valencia, spain * correspondence: eakos@rambler.ru; tel.: + - - - - received: may ; accepted: july ; published: july ���������� ������� abstract: background: the relationship between liver disease and neuropathology in hepatic encephalopathy is well known, but the genesis of encephalopathy in liver failure is yet to be elucidated. conceptually, the main cause of hepatic encephalopathy is the accumulation of brain ammonia due to impaired liver detoxification function or occurrence of portosystemic shunt. yet, as well as taking up toxic ammonia, the liver also produces vital metabolites that ensure normal cerebral function. given this, for insight into how perturbations in the metabolic capacity of the liver may be related to brain pathology, it is crucial to understand the extent of ammonia-related changes in the hepatic metabolism that provides respiratory fuel for the brain, a deficiency of which can give rise to encephalopathy. methods: hepatic encephalopathy was induced in starved rats by injection of ammonium acetate. ammonia-induced toxicity was evaluated by plasma and freeze-clamped liver and brain energy metabolites, and mitochondrial, cytoplasmic, and microsomal gluconeogenic enzymes, including mitochondrial ketogenic enzymes. parameters of oxidative phosphorylation were recorded polarographically with a clark-type electrode, while other measures were determined with standard fluorometric enzymatic methods. results: progressive impairment of liver mitochondrial respiration in the initial stage of ammonia-induced hepatotoxicity and the subsequent energy crisis due to decreased atp synthesis lead to cessation of gluconeogenesis and ketogenesis. reduction in glucose and ketone body supply to the brain is a terminal event in liver toxicity, preceding the development of coma. conclusions: our study provides a framework to further explore the relationship between hepatic dysfunction and progression of brain energy crisis in hepatic encephalopathy. keywords: hyperammonemia; liver; mitochondria; ketogenesis; gluconeogenesis; brain energy crisis . introduction hepatic encephalopathy (he) is a neuropsychiatric disorder developing in patients with severe liver disease. although the relationship between liver damage and neuropathology has been known for over a century [ , ], the genesis of encephalopathy as a result of impaired liver function is not yet completely clear. conceptually, the main cause of he is the accumulation of ammonia in the blood (hyperammonemia) due to impaired detoxification function of the liver or by portosystemic shunt, j. clin. med. , , ; doi: . /jcm www.mdpi.com/journal/jcm http://www.mdpi.com/journal/jcm http://www.mdpi.com https://orcid.org/ - - - x https://orcid.org/ - - - https://orcid.org/ - - - http://www.mdpi.com/ - / / / ?type=check_update&version= http://dx.doi.org/ . /jcm http://www.mdpi.com/journal/jcm j. clin. med. , , of allowing gut-derived neurotoxins that bypass the liver to reach the systemic circulation, thereby gaining access to the brain [ ]. other factors such as bacteremia, fungal infection [ ], alkalosis [ ], products of abnormal amino acid metabolism [ ], and various toxic substances [ ] may participate in disease development, but elevated blood ammonia entering the brain unhindered is believed to be the main toxic causative agent responsible for altered cerebral functions and clinical manifestations of he [ , ]. the molecular mechanisms of encephalopathy in the setting of hyperammonemia have not yet been fully elucidated and there is no specific medication for treating this abnormality, despite considerable knowledge of the syndrome. it has been established that ammonia-related neurotoxicity is characterized by brain energy failure [ ], disruption of mitochondrial oxidative phosphorylation [ ] and calcium homeostasis [ ], an imbalance among multiple neurotransmitter systems [ , ], disturbances of antioxidant defense systems [ , ], systemic neuroinflammation [ ], and abnormalities in the pattern of cerebral blood flow [ ]. therefore, he pathogenesis is viewed as a complex and multifactorial network of interdependent organ systems. thus, the impact on functional brain activity as a result of liver dysfunction may be wider than predicted based on increased blood ammonia levels due to the inability of the liver to perform its detoxification function. this hypothesis prompted us to investigate an alternative explanation for the effect of liver malfunction on brain pathology. it is known that the liver not only takes up toxic ammonia, but also plays a unique role in blood glucose homeostasis [ ]. given that glucose is the main brain energy metabolite, despite the recognized importance of some non-glucose substrates [ ], the liver is essential in homeostatic control of blood glucose levels. this process maintains adequate amounts of glucose for the brain and reflects its obligate dependence on the liver, indicating that under physiological conditions, the liver elaborates vital metabolites that assure normal cerebral function [ ]. as a result, unsteady blood glucose and oxygen delivery to the brain for even a short period causes brain damage, while chronic deficiency in these substrates leads to irreversible brain injury, thereby provoking coma development and death [ ]. owing to the large stores of glycogen and glycogenolysis and gluconeogenic pathways, the liver produces free glucose from glycogen and gluconeogenic substrates, which is released into the circulation to serve as a fuel source for the organs and particularly, the brain [ ]. if the blood contains insufficient amounts of glucose, only the liver [ ] is able to produce ketone bodies, which are utilized as an additional energy source in the brain. nevertheless, both liver ketogenesis and gluconeogenesis are understudied areas (with the exception of a few studies) in terms of their impact on the adequate supply of the brain with energy substrates and clinical manifestations of he [ ]. moreover, based on scattered and conflicting data from patients with fulminant liver failure or chronic liver diseases [ – ], it is impossible to assess how the reduction in ketone body and glucose output in the liver may be related to brain pathology. it should be noted that he studies on animal models also show contradictory results. after portacaval shunt in rats, plasma levels of acetoacetate and β-hydroxybutyrate were reduced [ ], or not significantly different from those in the sham-operated group [ ]. in the animal model of hyperammonemia initiated by a long term diet containing ammonia, the level of ketone bodies in the blood rose significantly, hence, synthesis and export of ketone bodies by the liver in the hyperammonemic rats were supposed to increase [ ]. in our studies performed in rat models of “pure” hyperammonemia produced by infusion of ammonium salts, we observed a significant decrease in the levels of both acetoacetate and β-hydroxybutyrate in the liver and blood of feeding animals, which suggested that hepatic ketogenesis can be inhibited immediately after increasing ammonia levels in the liver [ ]. given the importance of hepatic metabolic activity for providing fuel to the brain and an effective understanding of how perturbations in the metabolic capacity of liver cells may be related to brain pathology in he, we therefore focused on hepatic gluconeogenesis and ketogenesis in animal models, j. clin. med. , , of investigating acute ammonia intoxication in which the concentration of ammonia in the blood quickly increases to the level found in idiopathic hyperammonemia following lung transplantation [ ] and many other human pathologies [ ]. since these metabolic processes are energy-dependent and closely related to mitochondrial function and fatty acid oxidation [ ], we sought to study the effect of acute hyperammonemia on the hepatic mitochondrial function, including oxidative phosphorylation, fatty acid oxidative capacity, and how fluctuation of glucose and ketone body levels in the blood can affect brain bioenergetics and coma development. this research will advance understanding of the role of liver mitochondria in brain energy metabolism. . experimental section . . experimental design this study was conducted in accordance with the ethical principles formulated in the helsinki declaration for care and use of laboratory animals and the regulations of the european science association (revised in the instruction / /ec and formulated in the order of the ministry of health of the russian federation of . . № “regulations in laboratory practices”). . . animals groups of eight male wistar rats weighing – g were used. the animals were housed in a vivarium, four per split-level cage ( × × cm) at room temperature under a natural light regime. well-fed animals were fed a standard diet. for hepatic gluconeogenic and ketogenic process activation during fasting, some animals were starved twenty-four hours before the beginning of the experiment. the ammonia group was injected intraperitoneally with a lethal dose of ammonia acetate of mmol/kg. as observed previously [ ], the animals exhibited hyperventilation, clonic convulsions, and coma soon after ammonia injection and died in ± min. in this study, the rats were decapitated immediately after the first seizure, which usually occurred min after ammonia injection. in some experiments, the decapitation procedure was carried out at or min after ammonia loading. to obtain the values for the zero time point, rats were injected with ammonium acetate and decapitated immediately. control group animals were decapitated at different time points after injection of saline or sodium acetate. . . preparative and analytical methods blood was drawn from the retro-orbital plexus into citrate-treated tubes. plasma was deproteinized with % hclo and % ethanol and neutralized with koh to ph . ammonia was estimated by a microfluorimetric method as described by kosenko et al., [ ]. glucose, ketone bodies, oxaloacetate, and adenine nucleotides were determined by fluorometric enzymatic methods, as described earlier [ ]. biovision fluorometric assay kits (catalog # k - ), based on glucoamylase that hydrolyzes glycogen to glucose, were used to determine glycogen levels in freeze-clamped liver and brain samples. glycerol concentration was measured by an assay kit (sigma, cn fg ) according to the manufacturer’s instructions, using the procedure with a coupled enzyme assay. free fatty acids (ffa) were determined by the free fatty acid quantitation kit (sigma, cn mak ) using a coupled enzyme assay according to the manufacturer’s instructions. . . freeze-clamped liver and brain neocortex after decapitation, tissue specimens from liver and cortex tissues were removed and freeze-clamped as soon as possible in liquid nitrogen, and then, ground in a mortar into a fine powder. three milliliters of % cold (− ◦c) perchloric acid/ % ethanol mixture were added to . g j. clin. med. , , of of tissue powder and were extracted for min at − ◦c. analytical techniques for preparation of liver and brain tissue extracts were similar to those used for blood plasma extraction. . . isolation of liver mitochondria using a self-generated percoll gradient mitochondria were isolated from the remainder of the liver (after freeze clamping) by a combination of differential and self-generated percoll gradient centrifugation, according to a protocol developed by graham [ ]. mitochondrial protein was determined by the lowry method (lowry et al. ) with bovine serum albumin as standard [ ]. . . mitochondrial purity assessment a quantitative estimate of mitochondrial fraction purity was made using marker enzymes: lactate dehydrogenase (contamination of cytosol), glucose- -phosphatase (microsomal marker), urate oxidase (peroxisome marker), and ’-nucleotidase (plasma membrane marker). the enzyme activities were determined by previously described methods [ ]. β-galactosidase, used for detection of lysosome admixture, was determined according to the method described by graham ( ) [ ]. contamination of the mitochondrial samples with peroxisomes, microsomes, cytoplasm, plasma membranes, and lysosomes was . ± . %, . ± . %, . ± . %, . ± . %, and . ± . %, respectively. the yield of succinate dehydrogenase was more than % of total activity ( ± . and . ± . nmol/min x mg protein in mitochondria and homogenate, respectively) consistent with graham’s findings [ ]. together with a relatively low contamination of the mitochondria with other cellular organelles, the results indicate a high-purity mitochondrial fraction. . . study of mitochondrial respiration parameters of oxidative phosphorylation were recorded polarographically with a clark-type electrode using the analytical techniques described earlier [ ]. . . determination of pyruvate carboxylase activity (ec . . . ) liver mitochondria were disrupted by osmotic shock in volumes of mm potassium phosphate buffer (ph . ) containing . mm egta-k+ and . mm dithiothreitol (dtt), . mm phenylmethylsulfonyl fluoride (pmsf), . µm aprotinin, . µm, pepstatin, µm leupeptin and by three subsequent cycles of freezing–thawing. after the final thawing step, the sample was centrifuged at , g for min at + ◦c, and the resulting supernatant was used to determine enzyme activity by oxidation of nadh at nm using malate dehydrogenase (mdh) as a coupling enzyme [ ]. . . determination of phosphoenolpyruvate carboxykinase activity (ec . . . ) liver phosphoenolpyruvate carboxykinase (pepck) activity was determined in a cytosolic fraction obtained from the postmitochondrial supernatant after centrifugation at , × g for min at + ◦c. an assay was performed by coupling the pepck with mdh and by nadh oxidation at nm [ ]. . . microsome isolation and glucose- -phosphatase activity (ec . . . ) the microsomal fraction was obtained with a standard procedure of differential centrifugation without further purification. to remove the lysosome, the postmitochondrial supernatant was centrifuged at , × g for min at ◦c and the resulting supernatant was centrifuged at , × g for min at ◦c. the microsomal pellet was washed once with ml of incubation medium. the final pellet was resuspended in the medium, containing . m sucrose, mm hepes, ph . j. clin. med. , , of (sh solution), . mm dtt, . mm pmsf, . µm aprotinin, . µm, pepstatin, and µm leupeptin at a concentration of mg/ml, and was used immediately to determine microsomal intactness by estimating the latency of “low km” mannose- -phosphatase activities in untreated microsomes [ ]. for the glucose- -phosphatase (g- -pase) assay, microsomes ( µg of protein) were disrupted in sh solution containing . % triton x- at ◦ for min under constant gentle stirring. enzyme activity was measured by following inorganic phosphate liberated at nm using the method described by baginski, [ ]. . . activity of enzymes of ketone body synthesis in the liver for the enzymes of the -hydroxy- -methylglutaryl-coa (hmg-coa) pathway, the liver mitochondria were disrupted, and enzymes were solubilized using a technique similar to those used for pyruvate carboxylase determination. . . acetoacetyl-coa thiolase (ec . . . ) the enzyme was determined using the method described by williamson, [ ] with minor modifications. the standard reaction mixture contained mm tris-hcl (ph . ), mm mgcl , µm coa, µm acetoacetyl-coa, . mm dtt, and mm kcl. after pre-equilibration at ◦c, the reaction was initiated by adding – µg of the sample in a total volume of . ml and the change in absorption at nm was monitored for min. . . hmg-coa synthase (e.c. . l. . ) enzyme activity was estimated spectrophotometrically by measuring the initial rate of acetyl-coa-dependent disappearance of acetoacetyl-coa at nm according to quant et al., [ ], with minor modifications. the assay system contained mm tris/hcl, ph . , . mm dtt, mm acetyl phosphate, µm acetoacetyl-coa, µm acetyl-coa, – µg of sample protein and units of phosphate acetyltransferase (ec . . . ). hmg-coa synthase activity was measured as the difference in the rate before and after acetyl-coa addition. as mitochondrial hmg-coa synthase is inhibited by mg + [ ], the assay was performed in the absence of mgcl , where acetoacetyl-coa has an ε = . × m - cm - [ ]. . . hmg-coa lyase (e.c. . . . ) hmg-coa lyase activity was measured by a slightly modified wanders procedure [ ]. in short, – µg of the sample were incubated at ◦c in ml of medium containing mm glycylglycine (ph . ), mm mgcl , . mm dtt, and mm d,l- -hydroxy- -methylglutaryl-coa. at the time point of min, the reaction was stopped by perchloric acid precipitation ( . ml, %/ % ethanol) and the extracts were prepared using a technique similar to those used for the liver tissues, then, immediately used for fluorometric determination of acetoacetate [ ]. . . -hydroxybutyrate dehydrogenase (e.c. . . . ) -hydroxybutyrate dehydrogenase (hbdh) activity was measured in submitochondrial particles [ ] by the method described earlier [ ]. . . analysis of ketogenesis in mitochondria the rate of liver ketogenesis was measured in the isolated liver mitochondria using the technique of takeyama et al., [ ], and the end products of ketogenesis acetoacetate and β-hydroxybutyrate were determined by fluorometric enzymatic methods as described earlier [ ]. j. clin. med. , , of . . statistical analysis the results were expressed as mean ± sem (standard error of the mean). statistical processing of the results was performed using the program prizm . for windows (graphpad software, san diego, ca, usa). the normality of the distribution of variables was confirmed by the kolmogorov–smirnov test. pairwise comparisons were carried out using the student’s t-test, and multiple comparisons were performed using the anova and bonferroni corrections. . results . . metabolic changes in the liver and blood during starvation to establish how the presence of ammonia modifies the homeostatic function of the liver associated with maintaining glucose and ketone bodies levels in the blood under fasting conditions, we need to study the metabolic characteristics of starved animals without ammonia. we first examined concentrations of key metabolites in the blood and liver of control non-starved and starved animals (figure ). j. clin. med. , , x for peer review of the results were expressed as mean ± sem (standard error of the mean). statistical processing of the results was performed using the program prizm . for windows (graphpad software, usa). the normality of the distribution of variables was confirmed by the kolmogorov–smirnov test. pairwise comparisons were carried out using the student’s t-test, and multiple comparisons were performed using the anova and bonferroni corrections. . results . . metabolic changes in the liver and blood during starvation to establish how the presence of ammonia modifies the homeostatic function of the liver associated with maintaining glucose and ketone bodies levels in the blood under fasting conditions, we need to study the metabolic characteristics of starved animals without ammonia. we first examined concentrations of key metabolites in the blood and liver of control non-starved and figure . metabolites in the blood and liver of non-starved rats and rats starved for h. values are the means ± sem (n = ). significant differences in the values in “control” are estimated by the student’s t-test: *p < . , **p < . , ***p < . . as shown, h after starvation, glycogen in the liver was significantly depleted (figure ). simultaneously, there was a multifold increase in the concentration of glycerol, acetoacetate, and -hydroxybutyrate in the liver and blood; ammonia levels remained constant; ffa in the blood increased; glucose levels became lower, but still remained within the reference values. these results are consistent with the well-documented increase in hepatic gluconeogenesis, ureagenesis, and ketogenesis in starved rats. . . effect of acute ammonia intoxication on levels of liver and blood glucose, ketone bodies, ffa, and ammonia we next examined whether ammonia could affect glucose and ketone body levels during fasting-induced hepatic gluconeogenesis and ketogenesis. as shown in figure , the concentration of ammonia in the blood of control starved rats was . ± . mm and increased to . ± . mm (figure ) min after ammonia injection, which was close to the level observed in non-starved rats with hyperammonemia [ ] and in individuals with different pathologies [ , ]. figure . metabolites in the blood and liver of non-starved rats and rats starved for h. values are the means ± sem (n = ). significant differences in the values in “control” are estimated by the student’s t-test: * p < . , ** p < . , *** p < . . as shown, h after starvation, glycogen in the liver was significantly depleted (figure ). simultaneously, there was a multifold increase in the concentration of glycerol, acetoacetate, and -hydroxybutyrate in the liver and blood; ammonia levels remained constant; ffa in the blood increased; glucose levels became lower, but still remained within the reference values. these results are consistent with the well-documented increase in hepatic gluconeogenesis, ureagenesis, and ketogenesis in starved rats. . . effect of acute ammonia intoxication on levels of liver and blood glucose, ketone bodies, ffa, and ammonia we next examined whether ammonia could affect glucose and ketone body levels during fasting-induced hepatic gluconeogenesis and ketogenesis. as shown in figure , the concentration of ammonia in the blood of control starved rats was . ± . mm and increased to . ± . mm (figure ) min after ammonia injection, which was close to the level observed in non-starved rats with hyperammonemia [ ] and in individuals with different pathologies [ , ]. j. clin. med. , , of j. clin. med. , , x for peer review of figure . metabolites in the blood and liver of starved rats min after injection of ammonium acetate. values are the means ± sem (n = ). significant differences in the values in the group “ h starvation” are estimated by the student’s t-test: **p < . , ***p < . . hepatic glucose, -hydroxybutyrate, and acetoacetate levels rapidly decreased, and min after, the ammonia injection showed a %, %, and % decline, respectively, compared to control (figure ), suggesting that production of these metabolites in the liver was inhibited and a decrease in their blood levels was expected. indeed, although the concentration of ffa in the plasma of rats with hyperammonemia was accessible to the hepatic mitochondrial β-oxidation and to the maintenance of ketogenesis and gluconeogenesis, -hydroxybutyrate concentration decreased by %, acetoacetate virtually disappeared from the blood and the blood glucose level decreased to % of control (figure ). these results imply that ammonia could disturb either the oxidative function of mitochondria or the metabolic pathway of hmg-coa. in order to identify the possible role of liver mitochondria in disrupting the ketogenesis and gluconeogenesis processes, we next studied the effect of acute hyperammonemia on the hepatic mitochondrial function, including oxidative phosphorylation and fatty acid oxidative capacity, first evaluating the intactness and purity of isolated mitochondria. . . intactness and coupling efficiency of isolated mitochondria the intactness of isolated mitochondria was controlled by measuring the parameters of oxidative phosphorylation. the v , v , and vunc rates during oxidation of glutamate + malate as respiratory substrates were . ± . , . ± . , and . ± . ng atoms o/min per mg of mitochondrial protein, respectively. the respiratory control index (rci) and adp/o ratio were . ± . and . ± . , respectively (see table ). the rci values upon oxidation of other substrates—pyruvate + malate, succinate, oleate + carnitine, palmitoylcarnitine, and octanoate—were close to the theoretical values (table ) and indicated intactness and coupling of mitochondria at all three points of oxidative phosphorylation. table . parameters of oxidative phosphorylation in liver mitochondria of control starved animals and animals treated with ammonium acetate. substrate v v vu rci adp/o control animals starved for h pyruvate + malate . ± . . ± . . ± . . ± . . ± . glutamate + malate . ± . . ± . . ± . . ± . . ± . succinate + rotenone ± . . ± . ± . . ± . . ± . figure . metabolites in the blood and liver of starved rats min after injection of ammonium acetate. values are the means ± sem (n = ). significant differences in the values in the group “ h starvation” are estimated by the student’s t-test: ** p < . , *** p < . . hepatic glucose, -hydroxybutyrate, and acetoacetate levels rapidly decreased, and min after, the ammonia injection showed a %, %, and % decline, respectively, compared to control (figure ), suggesting that production of these metabolites in the liver was inhibited and a decrease in their blood levels was expected. indeed, although the concentration of ffa in the plasma of rats with hyperammonemia was accessible to the hepatic mitochondrial β-oxidation and to the maintenance of ketogenesis and gluconeogenesis, -hydroxybutyrate concentration decreased by %, acetoacetate virtually disappeared from the blood and the blood glucose level decreased to % of control (figure ). these results imply that ammonia could disturb either the oxidative function of mitochondria or the metabolic pathway of hmg-coa. in order to identify the possible role of liver mitochondria in disrupting the ketogenesis and gluconeogenesis processes, we next studied the effect of acute hyperammonemia on the hepatic mitochondrial function, including oxidative phosphorylation and fatty acid oxidative capacity, first evaluating the intactness and purity of isolated mitochondria. . . intactness and coupling efficiency of isolated mitochondria the intactness of isolated mitochondria was controlled by measuring the parameters of oxidative phosphorylation. the v , v , and vunc rates during oxidation of glutamate + malate as respiratory substrates were . ± . , . ± . , and . ± . ng atoms o/min per mg of mitochondrial protein, respectively. the respiratory control index (rci) and adp/o ratio were . ± . and . ± . , respectively (see table ). the rci values upon oxidation of other substrates—pyruvate + malate, succinate, oleate + carnitine, palmitoylcarnitine, and octanoate—were close to the theoretical values (table ) and indicated intactness and coupling of mitochondria at all three points of oxidative phosphorylation. . . oxidative phosphorylation in hyperammonemia the ammonia concentration in liver mitochondria as calculated per intramitochondrial water [ ] was ± . mm in control rats and . ± . mm in animals with hyperammonemia. upon oxidation of pyruvate + malate in liver mitochondria of hyperammonemic rats, v , rci and adp/o ratio were significantly lower ( %, %, and %, respectively) than the corresponding values for control samples (table ). the v and vunc rates did not differ statistically across the two j. clin. med. , , of groups. with glutamate + malate or succinate in the presence of rotenone, the v rate also significantly decreased in hyperammonemia by % and %, respectively, but with only glutamate + malate, rci fell slightly ( %), while the adp/o ratio was essentially unchanged in the presence of both substrates in ammonia-treated rats. with the substrates of lipid nature palmitoylcarnitine, octanoate, and oleate + l-carnitine, the respiration rate, v , in mitochondria from rats with hyperammonemia was markedly and equally inhibited (about %) compared to control. upon oxidation of palmitoylcarnitine, octanoate, and oleate + l-carnitine, rci in hyperammonemia significantly decreased by %, %, and %, respectively (table ). table . parameters of oxidative phosphorylation in liver mitochondria of control starved animals and animals treated with ammonium acetate. substrate v v vu rci adp/o control animals starved for h pyruvate + malate . ± . . ± . . ± . . ± . . ± . glutamate + malate . ± . . ± . . ± . . ± . . ± . succinate + rotenone ± . . ± . ± . . ± . . ± . palmitoyi-l-carnitine . ± . . ± . . ± . . ± . . ± . octanoate na . ± . . ± . . ± . . ± . . ± . oleic acid +l- carnitine . ± . . ± . . ± . . ± . . ± . ammonia-treated animals starved for h pyruvate + malate . ± . *** . ± . . ± . . ± . ** . ± . * glutamate + malate . ± . *** . ± . . ± . . ± . * . ± . succinate + rotenone . ± . *** . ± . ± . . ± . . ± . palmitoyi-l-carnitine . ± . *** . ± ± . ± . *** . ± . * na octanoate ± . *** . ± . * . ± . . ± . *** . ± . ** oleic acid + l- carnitine . ± . *** . ± . . ± . . ± . ** . ± . ** v , v and vunc are the mitochondrial respiration rates in the presence of µm adp (state ), in the absence of adp (state ), and in the presence of . µm carbonylcyanide-m-chlorophenylhydrazone (cccp, state of respiration uncoupling), respectively, and are expressed as ng atom o/min per mg of mitochondrial protein; rci = v /v is the respiratory control index. the adp/o ratio reflects the efficiency of oxidative phosphorylation and is the ratio of the amount of adp (in nanomoles) phosphorylated with the formation of atp to the amount of oxygen (in nanogram atoms) utilized in state . the substrates were added at final concentrations of: mm sodium pyruvate/ . mm potassium malate, mm potassium glutamate/ . mm potassium malate, mm potassium succinate/ µm rotenone, µm palmitoylcarnitine, µm octanoate na, and µm oleic acid/ mm carnitine. values are the means ± sem (n= ). significant differences in the values in the group “ h starvation” are estimated by the student’s t-test: * p < . , ** p < . , *** p < . . these results show that the oxidative metabolism of both lipid and non-lipid substrates is disturbed during a multifold increase in ammonia concentration in the liver mitochondria. from this, we can infer that ammonia has a dramatic impact on mitochondrial oxidative phosphorylation, the main energy supplier in hepatocytes [ ]. . . adenine nucleotides and nad/nadh ratio in liver mitochondria to estimate the effect of ammonia on availability of the energy necessary to maintain homeostatic liver function, we measured total mitochondrial adenine nucleotide content, as well as the nad/nadh ratio, which is known to regulate ketone body and glucose production [ ]. the results show that min after injection of ammonia into the starved animals, the atp content in mitochondria fell by % compared to control, while inversely, adp increased by %, and amp by % (figure ). the total content of adenine nucleotides (an) changed insignificantly, while the atp/adp ratio dramatically decreased by % during this time interval. this indicates that the energy potential of adenine nucleotides in liver mitochondria is decreased by the action of ammonia, but subsequent an degradation occurs relatively slowly. at the same time, the redox state of pyridine nucleotides in the mitochondrial matrix changed rapidly; having abruptly dropped upon starvation of control rats from to (data not shown), the nad/nadh ratio rose immediately up to . (by % higher than the initial value) min after injection of ammonia (figure ). j. clin. med. , , of j. clin. med. , , x for peer review of figure . distribution of adenine nucleotides and nad/nadh ratio in liver mitochondria from control starved rats and starved rats treated with ammonia. adenine nucleotide content in mitochondria was expressed as nmol/mg of protein. mitochondrial free [nad+]/[nadh] ratio was calculated from the components of the glutamic dehydrogenase ([nad+]/[nadh] = [a-ketoglutarate][nh +]/[glutamate], where the equilibrium constant was . [ ]. values are the means ± sem (n = ). significant differences in the values in the group “control” are estimated by the student’s t-test: *p < . , **p < . , ***p < . . at the same time, the redox state of pyridine nucleotides in the mitochondrial matrix changed rapidly; having abruptly dropped upon starvation of control rats from to (data not shown), the nad/nadh ratio rose immediately up to . (by % higher than the initial value) min after injection of ammonia (figure ). the findings agree with earlier reported results [ ] obtained using liver mitochondria from fed rats with hyperammonemia. they suggest that the more oxidized mitochondrial redox state, together with the diminished atp content and atp/adp ratio would result in cessation of energy production followed by a decrease in the activity of pyruvate carboxylase, the first atp-dependent mitochondrial enzyme that triggers gluconeogenesis [ ]. . . effect of ammonia on pyruvate carboxylase, phosphoenolpyruvate carboxykinase, and glucose- -phosphatase activity we next evaluated whether the ammonia would affect the activity of mitochondrial pyruvate carboxylase (pc) and other key rate-limiting gluconeogenic enzymes located outside the mitochondria. figure shows that min after injection of ammonia, an abrupt decrease in the figure . distribution of adenine nucleotides and nad/nadh ratio in liver mitochondria from control starved rats and starved rats treated with ammonia. adenine nucleotide content in mitochondria was expressed as nmol/mg of protein. mitochondrial free [nad+]/[nadh] ratio was calculated from the components of the glutamic dehydrogenase ([nad+]/[nadh] = [a-ketoglutarate][nh +]/[glutamate], where the equilibrium constant was . [ ]. values are the means ±sem (n = ). significant differences in the values in the group “control” are estimated by the student’s t-test: ** p < . , *** p < . . the findings agree with earlier reported results [ ] obtained using liver mitochondria from fed rats with hyperammonemia. they suggest that the more oxidized mitochondrial redox state, together with the diminished atp content and atp/adp ratio would result in cessation of energy production followed by a decrease in the activity of pyruvate carboxylase, the first atp-dependent mitochondrial enzyme that triggers gluconeogenesis [ ]. . . effect of ammonia on pyruvate carboxylase, phosphoenolpyruvate carboxykinase, and glucose- -phosphatase activity we next evaluated whether the ammonia would affect the activity of mitochondrial pyruvate carboxylase (pc) and other key rate-limiting gluconeogenic enzymes located outside the mitochondria. figure shows that min after injection of ammonia, an abrupt decrease in the activities of pc ( %), pepck ( %), and g pase ( %) occurred in the liver mitochondria, cytosol, and microsomes, respectively. these findings show that in starved animals characterized by enhanced hepatic gluconeogenesis, by which normal blood glucose concentration is maintained for at least h upon starvation, the accumulation of ammonia in different liver cell compartments causes a rapid and dramatic decrease in the activities of all key rate-limiting gluconeogenic enzymes; this results in a decline in basal rates of hepatic glucose production and fasting plasma glucose concentrations (figure ). j. clin. med. , , of j. clin. med. , , x for peer review of activities of pc ( %), pepck ( %), and g pase ( %) occurred in the liver mitochondria, cytosol, figure . effect of ammonia on the activity of pyruvate carboxylase (pc), phosphoenolpyruvate carboxykinase (pepck) and glucose- -phosphatase (g pase) in the liver of starved rats. the activities of pc, pepck and g p-ase in the liver mitochondria, cytosol, and microsomes are expressed in nmol/min per mg of protein of the corresponding fraction. values are the means ± sem (n = ). the significant differences in the values in the group “ h starvation” are estimated by the student’s t-test: ***p < . . these findings show that in starved animals characterized by enhanced hepatic gluconeogenesis, by which normal blood glucose concentration is maintained for at least h upon starvation, the accumulation of ammonia in different liver cell compartments causes a rapid and dramatic decrease in the activities of all key rate-limiting gluconeogenic enzymes; this results in a decline in basal rates of hepatic glucose production and fasting plasma glucose concentrations (figure ). . . effect of ammonia on enzyme activities of the hmg-coa pathway and acetoacetate production in the liver mitochondria of starved rats in some pathological conditions, there is a correlation between gluconeogenesis inhibition and reduced total blood ketone body concentrations, suggesting that inhibition of gluconeogenesis may decrease ketogenesis [ ], so we next examined whether hepatic ketogenic capacity in starved animals would actually be altered by ammonia. as can be seen in figure , its injection produced a significant decrease in the specific activities of acetoacetyl-coa thiolase ( %), hmg-coa synthase ( %), hmg-coa lyase ( %), and hbdh ( %). additionally, the acetoacetate formation rate decreased twice as much as control (figure ), simultaneously with its complete disappearance from the blood (figure ). figure . effect of ammonia on the activity of pyruvate carboxylase (pc), phosphoenolpyruvate carboxykinase (pepck) and glucose- -phosphatase (g pase) in the liver of starved rats. the activities of pc, pepck and g p-ase in the liver mitochondria, cytosol, and microsomes are expressed in nmol/min per mg of protein of the corresponding fraction. values are the means ± sem (n = ). the significant differences in the values in the group “ h starvation” are estimated by the student’s t-test: *** p < . . . . effect of ammonia on enzyme activities of the hmg-coa pathway and acetoacetate production in the liver mitochondria of starved rats in some pathological conditions, there is a correlation between gluconeogenesis inhibition and reduced total blood ketone body concentrations, suggesting that inhibition of gluconeogenesis may decrease ketogenesis [ ], so we next examined whether hepatic ketogenic capacity in starved animals would actually be altered by ammonia. as can be seen in figure , its injection produced a significant decrease in the specific activities of acetoacetyl-coa thiolase ( %), hmg-coa synthase ( %), hmg-coa lyase ( %), and hbdh ( %). additionally, the acetoacetate formation rate decreased twice as much as control (figure ), simultaneously with its complete disappearance from the blood (figure ). j. clin. med. , , x for peer review of activities of pc ( %), pepck ( %), and g pase ( %) occurred in the liver mitochondria, cytosol, figure . effect of ammonia on the activity of pyruvate carboxylase (pc), phosphoenolpyruvate carboxykinase (pepck) and glucose- -phosphatase (g pase) in the liver of starved rats. the activities of pc, pepck and g p-ase in the liver mitochondria, cytosol, and microsomes are expressed in nmol/min per mg of protein of the corresponding fraction. values are the means ± sem (n = ). the significant differences in the values in the group “ h starvation” are estimated by the student’s t-test: ***p < . . these findings show that in starved animals characterized by enhanced hepatic gluconeogenesis, by which normal blood glucose concentration is maintained for at least h upon starvation, the accumulation of ammonia in different liver cell compartments causes a rapid and dramatic decrease in the activities of all key rate-limiting gluconeogenic enzymes; this results in a decline in basal rates of hepatic glucose production and fasting plasma glucose concentrations (figure ). . . effect of ammonia on enzyme activities of the hmg-coa pathway and acetoacetate production in the liver mitochondria of starved rats in some pathological conditions, there is a correlation between gluconeogenesis inhibition and reduced total blood ketone body concentrations, suggesting that inhibition of gluconeogenesis may decrease ketogenesis [ ], so we next examined whether hepatic ketogenic capacity in starved animals would actually be altered by ammonia. as can be seen in figure , its injection produced a significant decrease in the specific activities of acetoacetyl-coa thiolase ( %), hmg-coa synthase ( %), hmg-coa lyase ( %), and hbdh ( %). additionally, the acetoacetate formation rate decreased twice as much as control (figure ), simultaneously with its complete disappearance from the blood (figure ). figure . activities of the enzymes of the hmg-coa pathway and rate of acetoacetate formation in the mitochondria of control and hyperammonemic rats. the activity of enzymes and the rate of acetoacetate formation are expressed in nmol/min per mg of mitochondrial protein. values are the means ± sem (n = ). significant differences in the values in the group “ h starvation” are estimated by the student’s t-test: * p < . ; ** p < . . to assess how fluctuations in glucose and ketone bodies in the blood could affect brain bioenergetics and coma development, we studied changes in concentrations of ketone bodies and glucose in the liver, blood, and brain after the first min of loading with ammonia. concentrations of acetoacetate and -hydroxybutyrate decreased within the first min by % and % in the liver, % and % in the blood (figure - a and figure - a; figure - b and figure - b), j. clin. med. , , of with no change in the brain (figure - c and figure - c). within the next min ( min after injection), the concentration of ketone bodies continued to decrease in the liver, blood, and finally, in the brain (figure - c and figure - c).j. clin. med. , , x for peer review of figure . time course of changes in acetoacetate, -hydroxybutyrate, atp, and glucose in the liver, blood, and brain in acute ammonia intoxication. values are the means ± sem (n = ). significant differences between the values with respect to the time point of min were estimated by anova analysis and corrected with bonferroni: *p < . , **p < . , ***p < . . figure . time course of changes in acetoacetate, -hydroxybutyrate, atp, and glucose in the liver, blood, and brain in acute ammonia intoxication. values are the means ± sem (n = ). significant differences between the values with respect to the time point of min were estimated by anova analysis and corrected with bonferroni: * p < . , ** p < . , *** p < . . j. clin. med. , , of similar changes in the concentration of atp (figure - a,c), the total content of adenine nucleotides, as well as the energy charge of adenylate (data not shown) and glucose (figure - a,b,c) occurred in the brain; concentrations of all metabolites remained unchanged within the first min after injection of ammonia, but sharply decreased just before seizures (by the time point of min), which suggests a time-dependent development of metabolic events—first in the liver, then in the blood and, finally, in the brain. thus, these results suggest that there is a relationship between the inhibition of hepatic gluconeogenesis, and ketogenesis, resulting in decreased availability of cerebral glucose and ketone bodies to the brain and bioenergetic collapse of the brain, accompanied by a cascade of pathological reactions [ ], leading to irreversible changes in the brain and development of coma as a terminal event in the toxicity of ammonia. . discussion although the relationship between liver damage and neuropathology has been known for over a century, the genesis of encephalopathy under impaired liver function is not yet completely resolved. nonetheless, more recent studies have provided evidence for a paramount role of the liver, reporting the main cause of he as ammonia accumulation in the blood and brain due to impaired detoxification function of the liver or by portosystemic shunt [ ]. in fact, the liver performs a myriad of functions, and in addition to filtering toxins, plays a unique role in the regulation of blood glucose homeostasis, crucial for normal cerebral function, since the brain neither synthesizes nor stores the required amount of glucose [ ]. as a result, unstable blood glucose and oxygen delivery to the brain, for even a short period, causes brain damage, while chronic deficiency in these substrates leads to irreversible brain injury, thereby triggering cognitive impairment, coma development, and death [ ]. additionally, when glucose is not readily available, the liver can produce ketone bodies, which are used by the brain as an alternative energy source. we previously showed that acute hyperammonemia leads to rapid and significant decrease in both acetoacetate and β-hydroxybutyrate levels in the liver and blood of non-starved rats. this suggests that hepatic ketogenesis can be inhibited immediately after increasing ammonia levels in the liver [ ], highlighting the role of deterioration of homeostatic liver functions in the occurrence of a brain energy crisis [ ]. in light of the notable lack of studies evaluating the effect of ketogenesis and gluconeogenesis in the liver on brain energy metabolism, our study focused on hepatic gluconeogenesis and ketogenesis, including oxidative phosphorylation in mitochondria and the oxidative ability of fatty acids in animal models of acute ammonia intoxication. in this model, ammonia concentrations in the blood quickly increase to the level found in idiopathic hyperammonemia associated with many human pathologies [ , ] and lead to rapid encephalopathy, which underlines the importance of our study. we revealed that oxidative phosphorylation in rat liver mitochondria was rapidly and progressively suppressed by high mitochondrial ammonia levels. while ammonium acetate min after administration to the starved rats induced a decrease in state rate and rci, state respiration remained unchanged during oxidation of lipid and non-lipid substrates (table ). these effects of ammonia were reproduced in liver [ ] and non-synaptic brain mitochondria [ ] of non-starved rats and according to the known action of the uncouplers [ ], it was suggested that ammonia seems to have an inhibitory but not uncoupling effect on state respiration and on the electron transfer along the respiratory chain. finally, deficiency in cytochrome oxidase [ ] and degradation of cytochrome-c in liver mitochondria of hyperammonemic rats [ ] lead to the same type of oxidative phosphorylation disorders. these findings could explain why ammonium-induced dysfunction of liver mitochondria leads to a sharp drop in the atp levels in these organelles. another consequence of ammonia accumulation is the no-dependent accelerated formation of superoxide radicals and a simultaneous decrease in the activity of antioxidant enzymes in liver j. clin. med. , , of mitochondria [ ]. we therefore hypothesized that no-dependent oxidative stress would be involved in the mitochondrial toxicity of ammonia. indeed, we found that despite increased blood glucagon and intramitochondrial levels of acetyl-coa (essential activators of pc) [ ] in starved rats, ammonia loading enhanced the nad/nadh ratio (figure ); adp level in mitochondria, a potent pc inhibitor [ ], together with atp deficiency led to a significant decrease in pc activity ( %, p < . ). since there is a causal relationship between pc activity and the whole gluconeogenesis pathway [ ], a decrease in activity of other gluconeogenic rate-limiting enzymes was expected. further studies (figure ) showed progressive decrease in liver pepck ( %) and g- -pase ( %) activity min after ammonia injection. thus, we have shown for the first time that in acute hyperammonemia, hepatic gluconeogenesis is inhibited at the level of at least three key enzymes. accordingly, liver and blood glucose levels began to decline within min ( % and %, respectively, compared to the zero time (figure - a,b)) after ammonia injection, but brain glucose (figure - c) and atp levels (figure - c) were unchanged and behavior of the animals did not differ from control for the same time period. later on, however, before the seizures, when blood glucose level fell below mm, brain glucose and atp concentration decreased by % and %, respectively, and no further significant changes were observed after repeated seizures and coma (figure - c, figure - c). therefore, ammonia-induced acute hypoglycemia resulting from the gluconeogenesis inhibition may precede the onset of seizures and can lead to coma and culminate in neuronal death. whereas the levels of ketone bodies in the liver and blood changed in a similar way to glucose levels after ammonia administration (figure - b, figure - b), suppression of ketogenesis was predictable. indeed, ammonium intoxication caused a significant (approximately twofold) decrease in activity of acetoacetyl-coa thiolase, hmg-coa synthase, hmg-coa lyase, and hbdh (figure ). as a result, the acetoacetate formation rate significantly reduced in mitochondria of ammonia-treated animals (figure ). we found that the reversal of ketogenesis of starvation occurred due to ammonia within min and became more pronounced just before the first seizure, with no change after the following seizures and coma (figure ). taken together, these findings indicate that high ammonia level in vivo has a dramatic effect on liver mitochondria as a prooxidant and redox stressor. more importantly, liver mitochondria dysfunction is an early and critical stage in development of ammonia-induced hepatotoxicity, preceding encephalopathy. given the time-dependent link between abnormalities in the liver and the development of seizures, we hypothesize that he is a state of the body, in which there is a discrepancy between demand in the brain for energy substrates produced by the liver and inability of the liver to generate these substrates. our study, thus, provides a framework to further explore the relationship between hepatic dysfunction and progression of brain energy crisis in hepatic encephalopathy. author contributions: e.k., l.t., and c.m. provided the original conception and designed the study; e.k., l.t., and g.a. analyzed data and discussed the results. the manuscript was written by e.k. and approved by all authors. all authors have read and agreed to the published version of the manuscript. funding: the study reported was funded by rfbr through the research project no - - and ministerio de ciencia e innovación - instituto de salud carlos iii (fis pi / ) co-funded with european regional development funds (erdf) and fundación ramón areces. conflicts of interest: the authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. references . von frerichs, f.t. a clinical treatise on diseases of the liver by dr friedrich theodor frerichs; the new sydenham society: london, uk, ; volume , pp. – . . hahn, m.; massen, o.; nencki, m.; pawlow, j. die eck’sche fistel zwischen der unteren hohlvene und der pfortader und ihre folgen fur den organismus. arch. exp. pathol. pharmakol. , , – . 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[crossref] © by the authors. licensee mdpi, basel, switzerland. this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license (http://creativecommons.org/licenses/by/ . /). http://dx.doi.org/ . / - ( ) -i http://dx.doi.org/ . /a: http://dx.doi.org/ . / - ( ) - http://dx.doi.org/ . /ajpendo. . . .e http://dx.doi.org/ . /a: http://dx.doi.org/ . /j. - . .tb .x http://dx.doi.org/ . /bj http://dx.doi.org/ . /ajplegacy. . . . http://dx.doi.org/ . /bj b http://dx.doi.org/ . /s - ( ) -x http://dx.doi.org/ . /nejm http://dx.doi.org/ . / - ( ) - http://dx.doi.org/ . /bf http://dx.doi.org/ . /s - ( ) - http://dx.doi.org/ . /jnr. http://www.ncbi.nlm.nih.gov/pubmed/ http://dx.doi.org/ . /db - http://creativecommons.org/ http://creativecommons.org/licenses/by/ . /. 	introduction 	experimental section 	experimental design 	animals 	preparative and analytical methods 	freeze-clamped liver and brain neocortex 	isolation of liver mitochondria using a self-generated percoll gradient 	mitochondrial purity assessment 	study of mitochondrial respiration 	determination of pyruvate carboxylase activity (ec . . . ) 	determination of phosphoenolpyruvate carboxykinase activity (ec . . . ) 	microsome isolation and glucose- -phosphatase activity (ec . . . ) 	activity of enzymes of ketone body synthesis in the liver 	acetoacetyl-coa thiolase (ec . . . ) 	hmg-coa synthase (e.c. . l. . ) 	hmg-coa lyase (e.c. . . . ) 	 -hydroxybutyrate dehydrogenase (e.c. . . . ) 	analysis of ketogenesis in mitochondria 	statistical analysis 	results 	metabolic changes in the liver and blood during starvation 	effect of acute ammonia intoxication on levels of liver and blood glucose, ketone bodies, ffa, and ammonia 	intactness and coupling efficiency of isolated mitochondria 	oxidative phosphorylation in hyperammonemia 	adenine nucleotides and nad/nadh ratio in liver mitochondria 	effect of ammonia on pyruvate carboxylase, phosphoenolpyruvate carboxykinase, and glucose- -phosphatase activity 	effect of ammonia on enzyme activities of the hmg-coa pathway and acetoacetate production in the liver mitochondria of starved rats 	discussion 	references regional differences in cell density and cell genesis in the olfactory epithelium of the salamander, <emphasis type="italic">ambystoma tigrinum</emphasis> exp brain res ( ) : _'ment branr � springer-verlag erratum regional differences in cell density and cell genesis in the olfactory epithelium of the salamander, ambystoma tigrinum mackay-sim, a. and patel, u. experimental brain research ( ) : - one page , paragraph , line , the sentence "this observation is consistent with a similar ante- rior-to-posterior gradient in the numbers of receptor cells reported recently for another urodele amphi- bian, triturus cristatus (dubois-dauphin et al. ) should read: "this observation is contrary to another urodele amphibian, triturus cristatus in which the posterior epithelium contained m o r e receptor cells than the anterior (dubois-dauphin et al. ). announcement the xth internatioal congress of neuropathology will take place in stockholm, sweden, september - , for further information contact x international con- gress of neuropathology, c/o stockholm convention bureau, p.o. box , s- stockholm, sweden. there will be four major symposia: 'energy crisis in the brain. causes and consequences' (chairman: f. plum, united states), 'viral infections' (chairman: r . t . johnson, united states), 'pathobiology of the axon' (chairman: s. waxman, united states) and 'neuro-transmitter and receptor systems in health and disease' (chairman: a. dahlstr m, sweden). in addition there will be daily plenary lectures on important developments in neuropathology and neu- robiology, slide seminars on muscle diseases, intra- cranial tumours and tropical infections of the nervous system. finally, free communications and workshops as well as poster sessions will be arranged. prof. p. sourander will serve as president of the congress and prof. a. torvik is the chairman of the program committee. wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ microsoft word - final-waset-rtc - -  abstract—tidal power can play a vital role in integrating as new source of renewable energy to the off-grid power connection in isolated areas, namely sandwip, in bangladesh. it can reduce the present energy crisis and improve the social, environmental and economic perspective of bangladesh. tidal energy is becoming popular around the world due to its own facilities. the development of any country largely depends on energy sector improvement. lack of energy sector is because of hampering progress of any country development, and the energy sector will be stable by only depend on sustainable energy sources. renewable energy having environmental friendly is the only sustainable solution of secure energy system. bangladesh has a huge potential of tidal power at different locations, but effective measures on this issue have not been considered sincerely. this paper summarizes the current energy scenario, and bangladesh can produce power approximately . mw across the country to reduce the growing energy demand utilizing tidal energy as well as it is shown that sandwip is highly potential place to produce tidal power, which is estimated approximately . mw by investing only us $ . million. besides this, cost management for tidal power plant has been also discussed. keywords—sustainable energy, tidal power, cost analysis, power demand, gas crisis. i. introduction enewable energy provides secure energy for any country to develop its infrastructural, socio-economic, agricultural, educational, health and community sector in stable condition. renewable energy means sustainable energy which is environment friendly, cost effective, non-polluting and future predicted energy sources. that is why developed countries are shifting their energy sector toward sustainable energy to maintenance their continuous growth. tidal is one of the sustainable energy sources and have huge potential to produce power from its energy [ ]. many countries are taking advantage from tidal energy to produce power for successfully transferring the energy sector into sustainable energy. bangladesh has also opportunity; sandwip is one of them, to use its facilities in various locations observing in proper way and guidance. it is mandatory to develop the energy sector before developing a country, in this regard tidal energy in sandwip can play a vital role to improve its locality with integrating development of country [ ]. sandwip project will be slightly helpful to mitigate the present energy crisis and shifting energy sector toward sustainable energy sources. this paper is mainly divided into four parts . energy sector md. alamgir hossain, md. zakir hossain and md. atiqur rahman are with the department of electrical & electronic engineering, dhaka university of engineering & technology, gazipur, bangladesh (corresponding e-mail: alamgir_duet@hotmail.com). condition and shifting . tidal power . feasibility study of sandwip, and . data analysis. ii. energy sector condition and shifting bangladesh, only % people are in grid connected [ ], is one of the lowest electricity consumptive country regionally and globally [ ]. the existing power system cannot produce sufficient power for the whole nation. scarcity of power is a principal infrastructural handicap in the development and growth of any country [ ]. the growth of the energy sector in bangladesh is not sufficient to meet the power demand, which is increasing by % annually [ ]. electricity supply in the rural and remote areas has been restricted due to transmission losses, high transmission costs, distribution costs, and greatly subsidized prices. growing population and financial activities drive the country toward high electricity demand. the shortage of electricity was mw to meet the high demand in , though the maximum electricity generation was , mw. according to [ ], in , the shortage of gas supply hinders the electricity generation around - mw. a. gas dependent power generation at present, power plant generates power utilizing . % of our gas reserve [ ], which is % of total gas, but consumption of gas demand increase at rate about % per year [ ]. however, at the present consumption rate of gas reserve leads it up to year [ ], whereas net remaining recoverable gas was . tcf at the end of . fig. shows the percentage of installed generation ( mw) capacity in bangladesh from various sources in . fig. the percentage of electricity generation in bangladesh from different sources [ ] and [ ] it is seen that from fig. , gas dependent power plant was installed . % of total installed capacity, but in actual case, some of other fuel dependent plants were abandoned, so total perspective and challenge of tidal power in bangladesh r md. alamgir hossain, md. zakir hossain, md. atiqur rahman world academy of science, engineering and technology international journal of energy and power engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e ne rg y an d p ow er e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/perspective-and-challenge-of-tidal-power-in-bangladesh/ http://scholar.waset.org/ - / power generation was more depend on gas than the scenario. sustainable energy sources use only . % of electricity production. fossil fuel use . % of total generation which is polluting the air, land, and water and emitting co . these pollution and emanation guide to environmental dilapidation which results bigger climate hazard and natural disasters. b. power generation planning power demand is increasing higher and becoming more as years go further, but growing high nature demand is going to be encountered by vulnerable energy source plan [ ], though recently need for power is being met by quick-rental power plants which require costly liquid fuels. to meet the next power demand, power development of bangladesh proposed roadmap for "the power system master plan ( )" recommending that the % of power generation would be coal-based but this planning is not environmentally friendly, security energy planning, rather it helps in the increasing global warming through breathing co . our total coal reserves are , million tons according to bangladesh's national energy policy . c. towards sustainable energy as fossil fuels are depleting at a higher rate, so we have to think to other sources mainly renewable. the country is going to be facing a severe energy crisis after the fossil fuel finish. so, country has no energy security in this respect. thus, sustainable energy is the only solution to get rid of this problem; which is becoming more acute as years proceed. to proceed fully toward renewable energy sources require some time, so in between these transaction periods fossil fuel can play a vital role. toward the moving secured and sustainable energy sources, tidal power can assist to play a role in this regard. iii. tidal power commercial ocean energy capacity (most tidal power facilities) remained at about mw at year's end, with little added in [ ]. the world's first and second large-scale tidal power plant, the rance tidal power station located at the estuary of the rance river, operated in is megawatts, which is generated by its turbines. it supplies . % of the total power demand of france [ ]. the world's biggest tidal power station operated by the korean water resource corporation in having total output capacity mw with mean operating tidal range . m is situated at sihwa lake tidal power station. total cost for this project was . million dollars met by the south korean government [ ]. incheon tidal power station which is under construction, another large tidal power station, is expected x = mw generating capacity at the incheon bay in south korea. total development and construction cost are hoping to reach us $ . billion with completion in june [ ]. a. bangladesh perspective bangladesh, electricity consumption per capita is only kwhr which is much less than any developed country [ ], has an extended costal area with - m tidal height ascend and descend [ ]. this height is adequate enough to generate power. tidal energy can be simply generated from the varying sea levels, and tides are more foreseeable than wind and sunlight. tidal currents can be precisely anticipated within % accuracy decades into the future [ ]. changing tidal can be used to produce electricity across a coastal bay with huge differences between low and high tides. electricity generation from tides is very analogous to hydroelectricity generation apart from that water; which is able to run in both directions, and electricity is produced using two-way turbines. the technology used in tidal power is very simple and has a probable life of more than years [ ]. b. advantage production of electricity from tidal is hours a day and days a year and has a highly efficiency ( %) competitive with other power sources. costal people can irrigate and make their life more solvent economically than before by means of tidal power. a set up expenditure to build a tidal energy plant is high, but the repairing costs are very low. the price of electricity has been paid off in or years after the capital costs and can be assumed to be almost zero. so, profit can be earned using tidal power technology [ ]. iv. feasibility study of sandwip sandwip, the eastern side of the delta region, is most approving locations for tidal power application. a flood control barrier exists around the entire island, and this contains sluice gates. these barrages and sluice gates can be used for electricity generation. therefore, the potential of tidal power is very accessible to be applied because the barrages are essential for controlling flow through turbines, which is also essential for controlling flood. this invalidates high capital cost for the engineering is already there or is crucial for cyclone protection. the energy available from a barrage is dependent on the volume of water. the potential energy contained in a volume of water is [ ], e= gha ( ) where, a = area of basin (m ) ρ = water density (kg/m ) g = acceleration due to the earth's gravity, and h = tidal range (m) output power, p = (energy (e) x turbine efficiency)/ (w) ( ) power generation from tidal can be computed using ( ). world academy of science, engineering and technology international journal of energy and power engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e ne rg y an d p ow er e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/perspective-and-challenge-of-tidal-power-in-bangladesh/ http://scholar.waset.org/ - / fig. sky scenario of sandwip from google map [ ] a rough estimate of investment and power production by tidal power in sandwip are shown below. fig. flow chart of estimated cost of sandwip project a. cost management and estimating economic support can be obtained from different sources of financial institutions, those help to develop sustainable energy system such as world bank climate investment, the adaptation and the least developed countries funds [ ]. moreover, clean development mechanism and carbon finance, internationally recognized mechanisms, give the opportunity to make funds for installing any sustainable project to develop a nation. the main aims of above mentioned organizations are to reduce gas emission and vulnerable situation for the adverse effect of climate change promoting green energy technology and sustainable developing the poorer communities of the developing world [ ]-[ ]. since, bangladesh is a most vulnerable country selected in cop conference and developing, which is suffering most for the climate change. so, tidal power project in sandwip will be positive for this country and getting available financial support from all the above cited organization. sandwip project is mainly divided into categories.  executable study: executable study involved in the proper location selection, land rights, environmental judgment, interconnection energy accord, system modeling, preliminary designs (electrical, mechanical and civil) and complete expenditure list. to do this study, approximately us $ need.  processing: it includes engaging managers, engineers, and laborers allowing sufficiency food, accommodation, and so on. besides, from the executable study outcome; different tendering process will be approaching, selecting, evaluating and supervising the whole activities worth is us $ .  constructional works: it is mainly divided into two parts a) civil works: this includes access roads, basin installation, power house establishment, and location setting. b) electrical and mechanical works: these include establishing essential equipment such as protection systems, turbines, generators, transmission lines, communication lines, controlling, monitoring and so forth. the total cost for these works is us $ and finally  operation and maintenance: these provide for the total project considering administrative costs like leases, remunerations, fees, etc. the nearly value of operating and maintenance is us $ . so, total cost need to implement and operate a tidal power base sustainable energy is around us $ . million. table i summarized of sandwip project parameter value tidal range . m no. of sluice gates no. of turbine uses basin area x m construction time years cost us $ . millions output power . mw v. data analysis sandwip has a great potential to produce power from tidal is around . mw, which is quite helpful to shrink power crisis through sustainable energy in bangladesh by investing only us $ . million. nonetheless, other parts of the country can produce energy around . mw from different tidal ranges [ ] considering basin area x m [ ], which is shown below. executable study (designing & modeling) $ processing (tendering & supervision) $ constructional works operating & maintenance $ civil $ electrical & mechanical $ sandwip project $ , world academy of science, engineering and technology international journal of energy and power engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e ne rg y an d p ow er e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/perspective-and-challenge-of-tidal-power-in-bangladesh/ http://scholar.waset.org/ - / table ii estimated power generation from different location of bangladesh name of the station mean tidal range (m) output power (mw) sandwip . . sadarghat (cht) . . mongla . . char changa . . cox’s bazar . . teknaf . . hiron point . . total . vi. conclusion with the increasing power demand in bangladesh, there is no substantial plan to meet the upcoming power crisis by renewable energy. the country has a great challenge in the upcoming days due to unsustainable dependent energy sources. in this respect, tidal power, as a renewable source of energy with numerous profits, can be a prime supplier for our future energy necessities increasing local hydroponic management with sandwip's socio-economic improvement. in our analysis it is found that bangladesh has immense potential of renewable energy sources like tidal power; which can add at least . mw power in sandwip area giving a solvent economic, social, and psychological improvement in this regional person. moreover, tidal power can generate total . mw from different places of the country, but still now no effective effort can be seen to produce power from this source. references [ ] lingchuan mei. overview of ocean wave and tidal energy. . available at: http://www.ee.columbia.edu/~lavaei/projects/lm.pdf. 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[ ] mishra s., singal s. k., khatod d. k. sustainable energy development by small hydropower with cdm benefits in india. international journal of ambient energy, ; ( ): - . [ ] ahmad s., kadir m. z. a. a., shafie s. current perspective of the renewable energy development in malaysia. renewable and sustainable energy reviews, ; ( ): - . [ ] bangladesh inland water transport authority (biwta), department of hydrography, tidal range table, bangladesh, august . [ ] tidal energy and its prospect in bangladesh. a thesis supervised by dr. farseem mannan mohammedy, dept. of electrical and electronic engineering (eee), bangladesh university of engineering and technology (buet). world academy of science, engineering and technology international journal of energy and power engineering vol: , no: , international scholarly and scientific research & innovation ( ) scholar.waset.org/ - / in te rn at io na l s ci en ce i nd ex , e ne rg y an d p ow er e ng in ee ri ng v ol : , n o: , w as et .o rg /p ub li ca ti on / http://waset.org/publication/perspective-and-challenge-of-tidal-power-in-bangladesh/ http://scholar.waset.org/ - / trade patterns and economic evolution econstor make your publications visible. a service of zbw leibniz-informationszentrum wirtschaft leibniz information centre for economics bingham, t. r. g. article — digitized version trade patterns and economic evolution intereconomics suggested citation: bingham, t. r. g. ( ) : trade patterns and economic evolution, intereconomics, issn - , verlag weltarchiv, hamburg, vol. , iss. , pp. - , http://dx.doi.org/ . /bf this version is available at: http://hdl.handle.net/ / standard-nutzungsbedingungen: die dokumente auf econstor dürfen zu eigenen wissenschaftlichen zwecken und zum privatgebrauch gespeichert und kopiert werden. sie dürfen die dokumente nicht für öffentliche oder kommerzielle zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. sofern die verfasser die dokumente unter open-content-lizenzen (insbesondere cc-lizenzen) zur verfügung gestellt haben sollten, gelten abweichend von diesen nutzungsbedingungen die in der dort genannten lizenz gewährten nutzungsrechte. terms of use: documents in econstor may be saved and copied for your personal and scholarly purposes. you are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public. if the documents have been made available under an open content licence (especially creative commons licences), you may exercise further usage rights as specified in the indicated licence. www.econstor.eu ~ n ~ n d trade patterns and economic evolution by t. r. g. bingham, helsinki * rnland is the last one of the non-applicant efta countries to conclude a free trade agreement with the ec. the author takes a favourable view of its prospects particularly since it has come into force just as a cyclical down-rum was getting under way, i a t the close of finland completed the prolonged process of redefining its relations with the enlarged european community by signing and ratifying a free trade agreement governing the exchange of industrial products. this accord is of particular importance for finland since about a half of its trade is with the enlarged community and because without it its major competitors in the rump efta - sweden, norway and austria - would have had a considerable competitive edge. a comparison with the fin-efta treaty both the short period that has elapsed s~nce the agreement came into force (january , ) and the considerable uncertainties engendered by the oil crisis make it impossible to predict with any confidence the full impact of the agree- ment on the finnish economy. but it is both pos- sible and rewarding to sketch the general effects and to delineate the cyclical impact of the change in the commercial environment. the climate in which the present agreement has been worked out is remarkably similar to that in which the fin-efta treaty was negotiated in . then, as now: [ ] finland followed a policy of resilient adapta- tion in order to safeguard its position in one of its major market areas; [ ] the agreement was of a purely commercial nature and designed to underscore finland's neu- trality, the keystone of its foreign policy; [ ] the agreement covered trade in manufactures and left the country free to follow its own agricul- tural and social policies; [ ] finland simultaneously took steps to improve its trading relations in the east as well as in the west. these similarities suggest that we can seek clues to the impact of the present agreement in the " bank of finland. the views expressed do not necessarily reflect those of the bank of finland. course of events following the signature of the fin-efta treaty. there were in fact two major consequences: a shift in the commodity compo- sition of exports and a change in the importance of various countries as markets for finnish goods. development of export structure prior to the efta period, the great bulk (about p.c.) of finnish exports came from its wood and paper industries. the overall percentage figures conceal the importance of trade in these products with other market economies because an unusually large share of finnish exports of metal and machinery manufactures went to the east bloc. greater access to the markets of the uk, sweden and the other efta countries opened the way for export diversification. exports of the forest based industries continued to expand and the degree of processing was upgraded con- siderably. but it was in the industries, which were not so strongly resource oriented and which had up to that point provided only a moderate quantity of exports, that growth was most rapid. exports of such labour intensive industries as the manu- facture of textiles and footwear were at the top of the export growth league, but the performance of some capital intensive branches such as the manufacture of basic metals and chemicals was also very respectable. on the whole the capital intensity of finnish exports tended to fall over the efta period as exports of the highly capital intensive paper industry declined in relative im- portance. this sort of export diversification was quite welcome because it provided employment for the country's reserves of labour in foreign ex- change earning activities. moreover, dependence on a narrow product base was reduced. this then is the general picture. more detailed information is given in table , which shows the commodity composition of exports at the begin- ning and end of the efta period and for pur- poses of comparison, in . the more rapid rise in the degree of processing during the efta intereconomics, no. , finland table shares of various product groups in finnish exports* product group main sub main sub main sub group group group group group group primary products . . . agriculture . . . forestry . . . industrial products . . . wood industry . . . paper industry . . . metal industry . . . other industry . . . � totals are not necessarily commensurate because soma prod- ucts, e.g., those of mining and quarrying, are omitted. source: statistical yearbook of finland, and . period is clearly reflected in the eight percentage point decline in the share of forestry exports, com- pared with a drop of only . p.c. in the preceding ten year period. the greater pace of export diver- sification during the efta period can also be seen. between and the share of metal and other industry products in total exports in- creased by about p.c., but in the following ten year period, the increase in the share was more than twice as great, i. e., p.c. the conclusion of the efta agreement also had an influence on the regional distribution of finnish exports, with efta countries gaining at the ex- pense of eec countries (cf. table ). table distribution of finnish exports by trading areas i year area l i efta . . . eec (orig;nal six) . . . east b~oc . . . other . . . ] uk, sweden, denmark, norway, austria, switzerland, portugal. ussr, poland, east germany, hungary, czechoslovakia, bul- garia, roumania. source: official statistics of finland i a, ; statistical year- book of finland, and . in the years following world war ii the six countries which would establish the eec steadily grew in importance as markets for finnish exports, and by they, like the efta countries, took over p.c. however, after the efta agreement came into force, their position gradually deteriorated so that by only slightly more than p.c. of finnish exports went to the eec, while somewhat less than half went to efta countries. the shift in the regional distribution of finnish exports following the country's adhesion to a free trade area indicates clearly that dismantling trade bar- riers has a definite allocative effect on trade flows. effects on trade and economic development if we extrapolate from these general trends and keep in mind the provisions of the free trade agreement with the european community and changes in the economic environment, we should obtain a fairly accurate picture of the main effects of the agreement on the pattern of trade and the course of economic evolution. the forest based industries will in all likelihood continue to expand at a more moderate pace than the other export oriented industries. the agreement with the ec provides for a general transition of / years, but for forest based products, this period is about three times as long. moreover exports of these products in excess of a certain limit to finland's former efta partners which are now members of the european community will face a temporary rise in tariffs. forest based exports will also be held in check by a shortage of raw materials. for some years the wood and paper industry has been able to process more than the annual growth of finland's forests, and raw wood has been imported. since the costs of transporting rough timber, reclaiming land and cultivating forests preclude sharp growth in the supply of primary inputs, expansion will have to take the form of raising further the degree of processing. unfortunately paper manufacturing is highly energy intensive - indeed over ten times more so than the manufacture of metal products - and it is likely that the higher price of oil will put this sector at a disadvantage relative to the newer export industries. despite these difficulties, the prospects for growth are not totally bleak since forecasts indicate that the supply of paper will fall short of demand for almost the entire length of the transition period. in recompense for the protection, which the com- munity has given its paper industries, finland has obtained a longer transition period for some of its newer industries. at present finnish duties on imports of machinery are relatively low and some of this industry's products such as wood processing machinery, cranes and boring equipment are quite capable of withstanding foreign competition. other sectors of this industry are not yet well established, and they will benefit from tariff protection for a longer time. moreover finland's footwear, leath- er, plastics, textile and clothing industries will also benefit from a slower transition period. the free trade agreement will give finland's com- petitive basic metal and chemical industries access to a much wider market, and it seems safe to expect that exports of these industries will grow intereconomics, no. , finland faster than those of most other sectors for metal and chemical industry exports have expanded very rapidly even though they have received little tariff protection and had to scale rather high tariff bar- riers. favourable for labour-intensive industries on the whole, the free trade agreement treats fin- land's labour intensive industries more favourably, and should thus help them increase their share in total exports. this will further help the diversifi- cation of both the economy and trade. as in the past, this development is to be welcomed. relative to most of its major market countries, finland has an abundance of labour, and the bulk of accepted trade theory would suggest that it should specialize in the production of labour-intensive products. but it must be recognized that finland is no longer a country with inexhaustable reserves of labour. it has ceased being a country of emigration, and in the most recent upswing severe shortages were experienced in some occupations and some re- gions, despite the persistence of structural un- employment in the northern and eastern parts of the country. a country with p.c. of its labour force employed in agriculture and forestry would appear to have a certain amount of labour which could be released for work in other sectors. how- ever, closer examination reveals that the average age of the farm population in finland is quite high. older farmers do not adjust easily or willingly to other jobs, and cannot be viewed as an important source of labour. the share of the primary labour force will fall over time, but primarily because the number of people retiring will exceed the number of new entrants. importance of energy supply no doubt the free trade agreement will affect the importance of the various trade groupings as markets for finnish exports. were other things equal, it would seem reasonable to expect the orig- inal six eec countries to increase their shares at the expense of both present and former efta members. however, we must again take note of the consequences of the oil crisis. finland im- ports the bulk of its oil from the soviet union at a price which is linked with the rotterdam index. the country's oil bill is expected to triple, and to pay it finland will have to increase the quantity of its exports to the soviet union with the result that the share of the east bloc will in all likelihood rise. we can thus expect a trend towards the trading patterns of the early s. the energy crisis is of such great moment that any assessment of the prospects for growth and economic evolution must make some mention of it. finland's position is not quite as precarious intereconomics, no. , as that of some of the other small nations of europe. some of its energy requirements are met domestically with hydroelectric power generated on its numerous rapids or through the burning of wood. finland has vast reserves of peat which could, at least in principle, be converted into petrol or used to run local heating plants, and its neutrality should make the country less subject to oil embargoes. however, the demand for energy is particularly great in this northern country. not only are its most important industries energy inten- sive, but the longer winters means that the need for oil for heating is great. moreover almost all domestic sources of energy - except peat - have been exploited, so that when energy policy plans were being formulated before the energy crisis occurred it was decided to in- crease the import of energy and to construct con- ventional power stations in the short run and nuclear power stations in the longer run. the most serious threat, however, comes from the potential fall in demand in finland's major foreign markets: the uk, the federal republic of germany and sweden. there is very little hope that a small, open economy can do to cushion the effects of a major decline in export demand. the timing of the present free trade agreement may, however, help in a small way. favourable turning of free trade agreement the other non-applicant efta countries con- cluded their agreements with the community at a time when world demand was high. finland, be- cause of the need to examine the foreign policy implications of the accord and to navigate the doc- ument through particularly choppy parliamentary waters, waited until the close of last year. a number of firms postponed investment decisions until the fate of the free trade agreement became clear, so that the agreement tended to bolster foreign demand and investment just as a cyclical down- turn of unknown proportions was getting under way. moreover, the bias in the agreement in favour of labour intensive industries should mean that it will provide particular help in buoying up employment. it would thus appear that the free trade agree- ment will help finland advance towards economic maturity by placing the newer, more expansive and less energy intensive industries at a still greater advantage. it should also lead to a rise in the shares of the original six as markets for finnish exports. although it was not consciously planned, the agreement was signed at a time that was quite propitious in light of cyclical conditions, so that on balance the agreement seems favour- able to the finnish economy in terms of both struc- tural and cyclical policy. page - © mantech publications . all rights reserved journal of thermal engineering and technology volume issue non conventional cooling system with lpg haware mubarakmiya a. g * , bhingade akshay p. * lecturers * department of mechanical engineering jspms’s bit, barshi corresponding author’s email id: mubarakhawre@gmail.com, akshay.bhingade @gmail.com doi: . /zenodo. abstract a non-conventional cooling system uses lpg (liquefied petroleum gas as refrigerant). domestic refrigerator which containing chlorine or fluorine item which is ban by international law due to ozone layer depletion and global warming problem. this work enables to boost the calorific value of gas by ensuring the vapor gas is going to burner. this project works on simple vapor compression refrigeration cycle. the vapor compression refrigeration cycle consists of compressor, condenser, capillary tube & evaporator. the compressor whose function is to increase pressure and temperature of vapor refrigerant and condenser is used for condensation of high temperature and high pressure vapor. these cycles are replaced by lpg cylinder i.e. (lpg cylinder has compressed & condensed refrigerant init). the lpg cylinder work as compressor and condenser. the high pressure lpg is passing through refrigeration circuit in which it passes through expansion valve or capillary tube & loop of evaporator. due to it the latent heat of liquefied petroleum gas gets converted from liquid to vapor which is called latent heat of evaporation of lpg. the cooling effect is obtained by using this latent heat of lpg in evaporator. hence only vapor is supplied to the burner. keywords: - lpg cylinder, capillary tube, evaporator, digital thermometer, burner. page - © mantech publications . all rights reserved journal of thermal engineering and technology volume issue introduction the non-conventional refrigeration system works on latent heat of vaporization of liquefied petroleum gas. this project gives output free of cost; it requires only the refrigeration circuit for getting cooling effect. the refrigeration circuit in non-conventional refrigeration system absorbs latent heat from liquefied petroleum gas, due to the heat absorbed liquefied petroleum gas gets converted to vapor. the heat absorb by liquefied petroleum gas is equal for latent heat of evaporation of liquefied petroleum gas. this project having creative idea which is suitably commercially in various sectors likes big restaurants, hotels and such places where continuous burning of lpg is required. due to the introduction of refrigeration circuit in between lpg cylinder and burner there is marginally improvement in calorific value than conventional. in normal refrigeration circuit use refrigerant to get the refrigerating effect for this to supply power to compressor for this purpose but here inverted lpg gives the cooling effect without any input. the non-conventional refrigeration system works on the principle same as the vapor compression (vcc) refrigeration system. instead of compressor & condenser use lpg cylinder which has pressure in between - bar for getting cooling effect. a. operation of vapor compression cycle vapor compression cycle is an improved type of air refrigeration cycle in this refrigerant used as working substance. the refrigerants generally used for this purpose are r a, r , ammonia (nh ), carbon dioxide (co ) and sulphur- dioxide (so ). the refrigerant generally used, don’t leave to the system, but it is circulated in the system alternately condensing and evaporating. in evaporating, the refrigerant absorbs its latent heat from the used solution which is for circulating it’s around the cold chamber and condensing; it gives out its latent heat to the circulating water of the cooler. the vapor compression cycle which is used for all purpose of refrigeration. it is used for all industrial purposes from a small domestic refrigerator to a big air conditioning plant. page - © mantech publications . all rights reserved journal of thermal engineering and technology volume issue fig. vapor compression cycle b. properties of liquefied petroleum gas lpg is a mixture of both saturated and unsaturated hydrocarbons (butane and propane). lpg market in india needs to become governed by indian standard code is- and the test by the methods is- . i. density lpg at atmospheric pressure and temperature is a gas; it is . times heavier than air. it is readily or finding liquefied under moderate pressures. the density of the liquid is approximately or near about half that of water and its ranges from . to . @ oc. ii. vapor pressure the pressure inside a lpg cylinder will be equal to the vapor pressure of corresponding temperature of lpg in the storage vessel. the vapor pressure is dependent on temperature as well as on the ratio of mixture of hydrocarbons. iii. flammability lpg has an explosive range of . % to . % volume of gas in air. it gives an indication of hazard of lpg vapor in low page - © mantech publications . all rights reserved journal of thermal engineering and technology volume issue lying area in the eventuality of the leakage or spillage. iv. combustion the combustion of lpg increases the volume of refrigerant in addition to the generation of heat. lpg requires up to times its own volume of air for complete combustion. v. odor lpg has only faint smell, and eventually, it is necessary to add some odorant, so that any leakage gas can easily be detected. ethyl mercaptan is normally used as stanching agent for this purpose. vi. color lpg is colorless in case of both liquid and vapor. during leakage the vaporization of liquid cools the atmosphere and condenses the water vapor in the form fog which may make it possible to see an escape of lpg. vii. toxicity lpg even though slightly toxic, it isn’t poisonous in vapor phase, but suffocates when in large concentrations due to the fact that it displaces oxygen. in view of this the vapor possess mild an aesthetic properties. c. component of non-conventional refrigeration system  lpg cylinder  strainer (filter)  capillary tube  regulator  evaporator box  digital thermometer  pressure gauge  hose tubing  burner fabrication stages the various stages of fabrication of the nccs model as follows:  fabrication of frame.  attachment of gas, pressure gauge, thermometer, capillary tube, burner.  mounting of capillary tube & rigid tube by brazing operation.  brazing: - brazing is a joining process which is used to joining two metals. these two metals are joined by melting filler metal. melting point of filler metal should be less than adjoining metal. page - © mantech publications . all rights reserved journal of thermal engineering and technology volume issue actual and fabricated model of evaporator fig. actual model of evaporator fig. fabricated model of evaporator page - © mantech publications . all rights reserved journal of thermal engineering and technology volume issue design parameter table no. design parameter sr. no. name of parameter notation . time t . initial temperature ti . final temperature tf . initial pressure pi . final pressure pf . heat absorbed in evaporator cabin q(evap.) . heat supplied by l.p.g q(l.p.g) formulas . heat absorbed in evaporator cabin- q (evapo) =m*cp*(ti-tf) here, (evapo) = q heat absorbed in the evaporator, j/s. mass (m) = mass of air supplied in the evaporator, kg. mass (m) =volume*density of air cp= specific heat of air . heat supplied by l.p.g – q (l.p.g.) = m*hfg here, q (l.p.g.) = heat supplied by l.p.g, j/s. m= mass of lpg, kg. hfg= latent heat of l.p.g, kj/kg observation table (result) in this observation table, find out the temperature differences (ti-tf) and pressure reducing from initial pressure of lpg at each minute. taken the reading at each minute for observations. as per taken observations observed that pressure is reduced its initial value at each observation. page - © mantech publications . all rights reserved journal of thermal engineering and technology volume issue table no. observation table time (t)min. initial temp. (ti)oc final temp. (tf)oc temp. difference ok initial pressure (pi)bar final pressure (pf)bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . design calculation of evaporator table no. heat absorbed in evaporator time (t)min. temp. difference (ti-tf) mass (m) kg. specific heat(cp) kj/kg q (evapo.) j/sec. . . . . . . . . . . . . . . . . . . . page - © mantech publications . all rights reserved journal of thermal engineering and technology volume issue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . testing and observations testing is nothing but a critical examination, observation or evaluation. it so the procedure of submitting a statement to such conditions or operations such that will lead to its proof or disproof or to its acceptance or rejection. a. testing for efficient cooling: number of trials are carried out on the model to obtain efficient cooling. the temperature is reduced gradually by designing the capillary in such a manner that the latent heat of evaporation takes place and the cooling effect takes place. b. testing for stable and reliable working: number of tests were carried out and the system was operated for a long duration to see for the leakages in the system and to see that the model behaves in a proper manner under high pressure. the fabricated models such as capillary and their brazing were also tested to their maximum. the results concluded that this non- conventional cooling system works properly and provides efficient cooling. page - © mantech publications . all rights reserved journal of thermal engineering and technology volume issue future scope india is facing an acute energy scarcity which is hampering its industrial growth and economic progress. setting up of new power plants is inevitably dependent on import of highly volatile fossil fuels. thus, it is essential to tackle the energy crisis through judicious utilization of abundant the non- conventional energy resources, such as biomass energy, solar energy, wind energy and geothermal energy. apart from augmenting the energy supply of renewable resources will help india in to mitigate changing the climate. india is heavily dependent on fossil fuels for its energy needs. most of the power generation performed by coal and mineral oil-based power plants they are responsible to greenhouse gases emission. the average per capita consumption of energy in india is around w; it is much lower than that of developed countries like japan, europe and usa etc. however, this figure is expected to rise sharply due to high economic growth and rapid industrialization. energy is a necessity and sustainable non-conventional energy is a vital link in industrialization and development of india. conclusion this paper concluded the use of one input get two output. input is lpg and gets output as cooling effect up to oc in evaporator and gets the pure vapor gas to burner due to this increasing the life and efficiency of gas. in addition, non- conventional energy has the potential to create many employment opportunities at all levels, especially in rural areas. an emphasis on presenting the real picture of massive non-conventional energy potential, it would be possible to attract foreign investments to herald a green energy revolution in india. so the world has already made a beginning to bring about the infrastructural changes in the energy sector so as to be able to choose the non-conventional energy development trajectory. references i. ibrahim husain shah & kundan gupta , “design of lpg refrigeration system and comparative energy analysis with domestic refrigerator”, (ijesrt) issn: - , july pp: - . ii. shank k. wang, handbook of air conditioning and refrigeration” edition. page - © mantech publications . all rights reserved journal of thermal engineering and technology volume issue iii. baskaran, p. koshy mathews, international journal of scientific and research publications”, volume , issue , issn - , september . iv. ashrae handbook . v. c.p. arora, “hand book of refrigeration and air conditioning”, by page no. . author’s profile haware mubarakmiya a. g lecturer at jspms’s bit, barshi mechanical engineering department mail id- mubarakhawre@gmail.com cite this article as haware mubarakmiya a. g, bhingade akshay p. ( ) “non conventional cooling system with lpg” journal of thermal engineering and technology, ( ), - http://doi.org/ . /zenodo. biofuels – a new challenge for nutritional science? public health nutrition: ( ), – doi: . /s invited commentary biofuels – a new challenge for nutritional science? ‘food is basically a net product of an ecosystem, however simplified. food production starts with a natural material, however modified later. injections of energy (and even brains) will carry us only so far. if the population cannot adjust its wants to the world in which it lives, there is little hope of solving the food problem for mankind. in that case the food shortage will solve our population problem.’( ) food crisis, energy crisis or water crisis? today the dominating global interest seems to be devoted to the energy situation, oil prices and their impact on the global financial situation. this may be why there is now so much interest in finding alternatives to oil as the main energy source. debate on the world’s future is still dominated by people from the industrialised world, but the real priority from a global perspective still is food and water for survival and optimal health for humankind. energy comes much lower on the priority list for human survival. dependence on oil is essentially a recent problem in affluent societies. energy from the petrochemical industry is a helper but is not the most essential component for food production. during the last decades there has been more interest in global water resources and on the impact of human activ- ities on the global water system( ). the impact of the cost of water on food production and food availability is a fun- damental challenge for nutritionists. the introduction of the ‘virtual water’ concept, and concern about the costs of water in export agriculture, indicate that environmental and socio-economic impacts of virtual water trade may well dominate political discussion in future. optimal production of biofuels the need to analyse energy efficiency in food production became more acute as a result of the energy crisis in the s( ). now there is increased interest in the production and use of biofuels. but we need a more holistic view, balancing the use of primary resources in farming areas for production of biofuels and with that for food and feed production. efficiency in energy conversion should also be addressed during all stages, from production of crops and their conversion into various energy sources such as ethanol, methanol and diesel, to distribution of biofuels to the final consumer. for example, today most of the ethanol used in swedish cars comes from brazil, because the ethanol in sweden derived from wheat is much less cost-effective. but energy costs for transport from brazil to sweden and for distribution of ethanol in sweden should also be taken into consideration. we are still at the beginning of developing biofuel technology. priority is now given to finding alternatives for power trains in vehicles, and to reduce the need for oil importation in the transport sector. so far the production of biofuels has been based on corn, wheat, soya, sugar cane and sugar beet, and (for diesel) from oil seeds such as rapeseed and palm oil. but these are all staple or common foods or ingredients. interestingly although potato is one of the crops with highest energy yield, it is not much discussed as an energy source in biofuel production, and nor is cassava, another energy-rich crop. from the nutritional point of view this is just as well, for it reduces the risk of a conflict with their roles as staple foods. it is not only foods that can be sources of biofuels. waste products from rapeseed cakes and straw have great potential, as does sewage treatment and the forestry industry. these alternatives involve less conflict between production of biofuels and production of food crops. hybrid and battery-powered electric vehicles and fuel cell vehicles are alternatives to conventional internal com- bustion engine vehicles using alternative biofuels such as ethanol, methanol and biodiesel( ). starving people are paying for the economic crisis ‘the evidence now before us – of a world which can produce automobiles, television setsy at a greater speed than the increase in population, but is simultaneously menaced by mass starvation – is disturbing.’( ) the global economic turmoil during the last two years demonstrates the incompetence of economists and policy makers to handle the socio-economic situation. the stage has been set for those who play vast pyramid or mono- poly games. in many respects the economic crisis today is artificial, started by unethical gamblers on the stock market. it is not a result of a sudden and unforeseen crisis in the availability of primary resources for feeding a population. after all, it is food and water that represent our basic needs. we do not drink oil, nor do we eat dollar or euro notes. it is a luxury crisis. it means that we have to reduce our overconsumption of cars and luxury products, r the author downloaded from https://www.cambridge.org/core. apr at : : , subject to the cambridge core terms of use. https://www.cambridge.org/core and this leads to unemployment, malnutrition and public health problems. but the price is not paid by the affluent societies or the rich. the chief executives who have led our companies into ruin and bankruptcy are overpaid, and in some cases even receive extra bonuses if they leave the job they did not manage to handle. those who have to pay for their mismanagement are impoverished people in low-income countries, who face increased prices of food. increased malnutrition is the result of economic mismanagement. starving people usually do not dream of having a car. why are the food and drink and associated industries still considered as positive forces in policy making, whereas the interests of consumers and of health are regarded as burdens on society? when will human capital in the form of a healthy population be more valued than industrial production of luxury products, which may solve short-term economic problems but often include environmental problems? why are ministers of industry, agriculture and trade ranked higher than ministers of social welfare? how can politicians discuss solutions to correct maldistribution of primary resources, when they do not know what the basic needs are? why have nutritionists failed to influence food policy? we nutritionists have failed to get our messages accepted by politicians. one reason may be that those involved in macroeconomic and international policy and trade are seldom undernourished. undernutrition of protein or energy, or micronutrient deficiency, rarely afflicts politi- cians or un personnel. on the contrary, they might have a problem of overnutrition, showing as obesity, cvd, type diabetes and cancer. interestingly these diseases are still not taken very seriously as major public health problems by policy makers, although they dominate the causes of death in the affluent societies and now increasingly in lower-income countries. since the second world war our focus on major nutri- tional problems has changed from a focus on protein needs to energy needs. such a change has had and still has an enormous impact on the direction of agricultural policy. better knowledge about the primary nutritional needs in relation to the potentials of agricultural production must be based on public health perspectives rather than on strict agro-economic aspects or farmers’ income. two crops, potato and cassava, imported from latin america to europe and africa beginning in the th century, illustrate the role of nutrition for socio-economic devel- opment. they have probably saved more lives than any macroeconomic policy actions. it was the introduction of potato from the alto plana region in latin america that helped the farmers of ireland to solve their subsistence farming and also to some extent cash production. but it was also monoculture of the highest-yielding potato crops as cash crops to solve short-term economic problems of the poor, in combination with crop failure, that resulted in the great irish famine. cassava, on the other hand, was blamed for its low protein content during the s as aggravating protein malnutrition, until its great potential as a cheap and easily available energy source was revealed and cassava became recognised as a life saver in low-income countries and communities. nothing is new under the sun nutrition science is often said to be a new discipline. nothing could be more wrong. the burden of deficiency diseases was the primary focus of medicine for many cen- turies until the pharmacological era of the th century. the development of biochemistry during the th and th centuries focused on the metabolic processes in the body, including the roles of nutrients, trace elements and vitamins, and a number of scientists directly or indirectly engaged in the vitamin and nutrition sector won nobel prizes. who can solve nutrition problems? in the th century nutritionists observed endemic and epidemic malnutrition in the countries now described as the low-income countries. some realised that the cause was maldistribution of resources. however, nutritional problems are multifactorial and have to be approached in a transdisciplinary and intersectoral way. nutritionists cannot solve global problems by themselves. nor can those skilled in anthropology, political or cultural issues evaluate priorities in food production or public health, without help from the nutritional and agricultural sciences. when people identified as policy and socio-economic experts entered the field, they started by discussing macroeconomic solutions, and relegated medical people and nutritionists to deal with marginal micro-problems. some administrators within the un system still argue that nutritionists have no role to play in solving the global nutrition problems, and call for socio-economic mea- sures( ). it has even been argued that knowledge of human nutrition simply is of no importance. thus: ‘much more important is knowledge and experience in for example anthropological and cultural issues, political analysis, communication and mobilization skills’. this is an alarming and astonishingly short-sighted statement. it was the nutritionists and physicians who called for a holistic view on prevention of malnutrition, and for help from anthropologists and socio-economic experts. eco- nomic progress does not necessarily lead to improved nutritional status. malnutrition persists even in apparently food-secure households. physicians have shown the evil circle between malnutrition and infection, and also the long-term effect of malnutrition on mental and physical l hambræus downloaded from https://www.cambridge.org/core. apr at : : , subject to the cambridge core terms of use. https://www.cambridge.org/core development. the macroeconomists and the socio- anthropologists did not do this. high infant mortality caused by introduction of breast milk substitutes in low-income countries as a result of marketing efforts from big multinational companies, was identified by doctors and nutritionists. it was they who led the battle against the marketing actions from multi- national food companies, not the policy makers nor the socio-economic administrators. time for nutritionists to engage in the debate on biofuels the new interest in production of biofuels is a challenge to us all. in the enthusiasm to test new approaches to solve global energy problems, we must analyse long-term perspectives and indirect effects on other markets. just as we earlier got misled in evaluation of the role of cassava for human nutrition, there is now a great risk that the interest for production of biofuels may conflict with interest for optimal food production. increased production of biofuels may be deleterious for food production if the wrong crops are chosen. but it could also increase eco- nomic power in agricultural production and thereby help to increase food security. optimal use of production area thus calls for optimal selection of crops under prevailing cir- cumstances, which can increase efficiency in food pro- duction, transport, food industry and food handling. we need sustainable energy systems. but we also need increased cooperation between nutritionists and agri- cultural scientists, and those involved in the development of sustainable biofuel technology. increase in energy resources must be combined with reduction of malnutri- tion and poverty. a systems approach is needed, whereby nutritionists, agronomists and those engaged in technical change and innovation within the bioenergy sphere, all work together. sustainable food production calls for sustainable energy resources. we must support increased cooperation between disciplines from all fields involved in optimal socio-economic development and also public health protection. bridges need to be built by broad-minded scientists who are well established within their respective disciplines, and open-minded policy makers. this will stimulate interdisciplinary approaches to solve the future problems of humankind regarding energy availability and access to food for everybody. so what is to be done? > defend the value of human capital for development of society against the dominant over-evaluation of indus- trial production by politicians and macroeconomists. > identify the dominant nutrition and public health problems in various societies, to support policies that help vulnerable groups and lead to optimal health for all. > find the best balance between dietary recommenda- tions and the potential resources for food production, especially in respect of small and family farmers. > stimulate sustainable agricultural production by balancing production costs with costs for transport, distribution and storage, in small- as well as large-scale production. > engage with energy environmental scholars, to find the best balance between food crops, feed crops and energy crops for sustainable agricultural production. with this ambition, and an innovative scientific approach to develop sustainable energy and food pro- duction, we can together solve the problems for feeding the world population with food and energy for tomorrow! leif hambræus unit for public health nutrition department of bioscience and nutrition novum, karolinska institutet se- huddinge, sweden email: leif.hambraeus@ki.se references . steinhart cs & steinhart ce ( ) energy use in the u.s. food system. science , – . . hoekstra ay & hung po ( ) globalisation of water resources: international virtual water flows in relation to crop trade. global environmental change , – . . åhman m ( ) primary energy efficiency of alternative powertrains in vehicles. energy , – . . georgescu-roegen n ( ) the entropy law and the economic process. cambridge, ma: harvard university press. . fsn forum discussion ( ) putting people first: nutrition, a key to integrated programming for poverty reduction? st december to th february . http://km.fao.org/ fileadmin/user_upload/fsn/docs/proceedings_nutrition_ integrated_programming.doc invited commentary downloaded from https://www.cambridge.org/core. apr at : : , subject to the cambridge core terms of use. https://www.cambridge.org/core shieldsquare captcha we apologize for the inconvenience... ...but your activity and behavior on this site made us think that you are a bot. note: a number of things could be going on here. 	if you are attempting to access this site using an anonymous private/proxy network, please disable that and try accessing site again. 	due to previously detected malicious behavior which originated from the network you're using, please request unblock to site. please solve this captcha to request unblock to the website 	 		you reached this page when trying to access 		https://iopscience.iop.org/journal/ - from 		 . . . on 		april , : : utc 	 [pdf] development of a wind forced chiller and its efficiency analysis | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /j.apenergy. . . corpus id: development of a wind forced chiller and its efficiency analysis @article{ting developmentoa, title={development of a wind forced chiller and its efficiency analysis}, author={chen-ching ting and jing-nang lee and chun-hong shen}, journal={applied energy}, year={ }, volume={ }, pages={ - } } 	chen-ching ting, jing-nang lee, chun-hong shen 	published 	engineering 	applied energy until now, the technical development of wind force is mainly combined with electrical generator and already achieves the skillful technique in application. in this paper the newly developed windchiller directly applies the mechanical energy of wind force for refrigeration instead of the traditional electrical/mechanical energy conversion. the devise avoids energy loss during the two to-and-fro energy conversion processes between wind force and electrical energy. the special finished wind… expand view via publisher ir.lib.ncut.edu.tw save to library create alert cite launch research feed share this paper citations view all figures and tables from this paper 	 figure 	 table 	 figure 	 table 	 figure 	 figure 	 figure 	 figure 	 figure 	 figure 	 figure 	 figure 	 figure view all figures & tables citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency developing the dual system of wind chiller integrated with wind generator 	chen-ching ting, chen-wei lai, c. huang 	engineering 	 	 save alert research feed experiment study on lift and resistance wind energy fan 	wu yu-ling, z. wang, qi runsheng 	environmental science 	 save alert research feed development of a wind directly forced heat pump and its efficiency analysis 	ching-song jwo, zi-jie chien, y. chen, chao-chun chien 	environmental science 	 	 	pdf save alert research feed a study on model experiment and aerodynamic match of wind energy fan (wef) 	z. wang, y. wu, siqiang lu, xi meng, j. zhang 	environmental science 	 	 save alert research feed theoretical analysis of a wind heating conversion and long distance transmission system 	w. cheng, bing-chuan han, y. nian, b. han 	engineering 	 	 save alert research feed developing the full-field wind electric generator 	chen-ching ting, li-yu yeh 	engineering 	 	 save alert research feed model experiment study for ventilation performance improvement of the wind energy fan system by optimizing wind turbines 	ziyun wang, s. wang, ren jiayou, xi meng, y. wu 	environmental science 	 save alert research feed design and experimental performance of an off-grid ice storage system driven by distributed wind energy 	linbin zeng, g. li, m. li, z. feng, l. yang, x. luo 	environmental science 	 	 save alert research feed developing a mechanical roadway system for waste energy capture of vehicles and electric generation 	chen-ching ting, d. tsai, chung-cheng hsiao 	engineering 	 	 save alert research feed experimental investigation of energy dissipation in the multi-cylinder couette-taylor system with independently rotating cylinders 	a. serov, a. nazarov, v. mamonov, v. terekhov 	engineering 	 	 save alert research feed references showing - of references sort byrelevance most influenced papers recency a novel power splitting drive train for variable speed wind power generators 	xueyong zhao, p. maißer 	engineering 	 	 save alert research feed the starting and low wind speed behaviour of a small horizontal axis wind turbine 	a. k. wright, d. wood 	engineering 	 	 	view excerpt, references background save alert research feed the impact of large scale wind power generation on power system oscillations 	j. g. slootweg, w. kling 	engineering 	 	 	view excerpt, references background save alert research feed application of a control algorithm for wind speed prediction and active power generation 	p. flores, a. tapia, g. tapia 	engineering 	 	 	pdf save alert research feed mean wind and turbulence characteristics due to induction effects near wind turbine rotors 	d. neff, r. meroney 	engineering 	 	 	view excerpt, references background save alert research feed characteristics of wind forces acting on tall buildings 	n. lin, chris letchford, y. tamura, b. liang, o. nakamura 	engineering 	 	 save alert research feed wind energy explained: theory, design, and application [book review] 	s.s. venkata, s. krishnamurthy 	engineering 	ieee power and energy magazine 	 	 	view excerpt, references background save alert research feed refrigeration and air conditioning 	w. f. stoecker, j. w. jones 	engineering 	 	 	view excerpt, references background save alert research feed assessing the suitability of wind speed probabilty distribution functions based on wind power density 	a. celik 	environmental science 	 	 	view excerpt, references background save alert research feed optimal electricity market for wind power 	h. holttinen 	economics 	 	 save alert research feed ... ... related papers 	abstract 	figures and tables 	 citations 	 references 	related papers stay connected with semantic scholar sign up about semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue wild energy plant resources, conservation and sustainable use of sanqingshan in eastern china ieri procedia ( ) – - © the authors. published by elsevier b.v. selection and peer review under responsibility of information engineering research institute doi: . /j.ieri. . . international conference on agricultural and natural resources engineering wild energy plant resources, conservation and sustainable use of sanqingshan in eastern china guowen xie*, xiangqin li, lika li, yueling jiang, yisheng zheng, weirong wang guangzhou key laboratory for functional study on plant stress-resistant genes, guangzhou university, guangzhou , china abstract accompany with the energy crisis and pollution, came the energy plant, the biomass energy relying mainly on energy plant should be developed. energy plants are vital strategic resource to secure the state energy supply and to respond possible energy crisis at present and in the future. sanqingshan has a wide variety of the wild energy plant resources, having an estimate of more than species. this paper studies on the species diversity status, protection and sustainable use of the wild energy plant resources in sanqingshan. some energy plants are characterized by fast growth, high yield, high oil content, good burning quality, and potential exploitable worth, including lauraceae, magnoliaceae, theaceae, sapindaceae, prunus of rosaceae and carya of juglandaceae and jatropha curcas, sloanea hemsleyana, sloanea sinensis, and so on. besides to biodiesel, the development of energy plants can bring various resources such as wood, fragrance materials, fruits, medicine materials and rubber, for seeds are the main oil containers in these plants, in the same time. some suggestions on the sustainable use and development of energy industry in the region were put forward. © . published by elsevier b.v. selection and peer review under responsibility of information engineering research institute key words: energy plant, wild resources, environmental conservation, sustainable use, sanqingshan * corresponding author. tel.: + - ; fax: + - - . e-mail address: xieguowen @ .com. available online at www.sciencedirect.com © the authors. published by elsevier b.v. selection and peer review under responsibility of information engineering research institute sciencedirect open access under cc by-nc-nd license. open access under cc by-nc-nd license. http://creativecommons.org/licenses/by-nc-nd/ . / http://creativecommons.org/licenses/by-nc-nd/ . / guowen xie et al. / ieri procedia ( ) – . introduction accompany with the energy crisis and pollution, came the energy plant, the biomass energy relying mainly on energy plant should be developed. energy plants are vital strategic resource to secure the state energy supply and to respond possible energy crisis at present and in the future (ragauskas et al, ; wen, ). development biomass energy and selection energy plant to alternative fossil fuels is an important way to ease the energy crisis and reduce greenhouse gas emissions. energy plant with its rich resources, renewable, zero emissions of carbon dioxide and other advantages will become an important alternative energy sources (liu et al, ; wan and fang, ; ramos et al, ). sanqingshan is located on east north of jiangxi province, eastern china, it has a wide variety of wild energy plants, many of them has not been used, therefore, the development and utilization of wild energy plant resources is of great potential. by developing and utilizing the wild energy plant resources, we can form some advantages as new industries, in order to avoid loss of wild energy plant resources when use plant resources, protection should be taken, and the protection is a long-term use for wild energy plants. . species diversity status of wild energy plant resources in sanqingshan sanqingshan has diverse biodiversity, based on the investigation mentioned (peng et al, ), there are species higher plants(including culture species)from genera belonging to families, among them, there are species of bryophyta from genera belonging to families, species of pteridophyta from genera belonging to families, species of gymnopermae from genera belonging to families, and species of angiospermae from genera belonging to families. energy plants are plant resources of edible oil, industrial oil and paint raw materials, and there are about species of energy plants, account for an estimated % of wild plant resources in sanqingshan region. in this area, the camellia oleifera, c. japonica and c. chekiang-oleosa of camelliaceae are rich and have high oil content, and can be used for human consumption. tea seed oil of c. sinensis can be used as lubricants of precision machinery and lubricants. lindera megaphylla of lauraceae is evergreen tree, common in evergreen broadleaved forest and brush land, and its kernel of seed is non-drying oil, which is used for soap raw material, and its seed oil can be also used for soap raw material. litsea cubab is common, born in hillsides, hillsides, shrub, woodland or on-street and other places, and its seed oil is used for industrial oil. mallotus apelta of euphorbiaceae is a shrub or small tree, common, born in shrubs or the sides of villages and its seed oil is used for soap and so on. celtis sinensis of ulmaceae is decduous tree, born on forest edge, village, street, and its wood is light and hard that can be made of made of furniture. its seed oils can be used for lubricating oil. ailanthus altissima of simaroubaceae is deciduous tree, common in the region and born in hillside, limes of villages, and seeds can be extracted to oil. moreover, energy plants have pinus massniana of pinaceae, cunninghamia lanceolata of taxodiaceae, taxus wallichiana var. mairei of taxaceae, cinnamomum camphora, c.micranthum, c. porrectum, c. sudauenium, lindera aggregata, lindera communis, lindera glauca, litsea cubeba, l. rotundifolia var. oblongifolia, machilus grijsii, machilus velutina, machilus thunbergii, phoede sheareri of lauraceae, capsella bursapastoris, cardamine hirsuta and lepidium virgnicum of cruciferae, celosia argentea of amarantaceae, idesia polycarpa and xylosma congesta of flacourtiaceae, camellia breuistyla, c. cuspidate and ternstroemia gymnanthera of camelliaceae, firmiana simplex of sterculiaceae, urena lobata of malvaceae, glochidion puberum, mallotus lianus, sapium discolor, sapium japonicum and sapium sebiferum of euphoriaceae, lauroceasus phaeosticta of rosaceae, aeschynomne indica, daldergia, millettia and sophora flauescen of papilionaceae. lithocarpus glaber of fagaceae, broussonetia papyrifera and ficus pumila of moraceae, boehmeria niuea of urticaceae, paliurus ramosissimus of rhammaceae, melia azedarach of meliaceae, euscaphia japonica of staphyleaceae, guowen xie et al. / ieri procedia ( ) – toxicodenrom succedaneeum of anacardiaceae, pterocaya stenoptera of juglandaceae, alangium chinensis of alangiaceae, aralia chinensis of araliaceae, umbelliferae, of umbelliferae, ardisia crenata of myrsinaceae, styrax suberifolus of styracaceae, symplocos sumuntia, s. chinensis of symplocosceae, ligustum sinensis of oleaceae, gardenia jasmindes of rubiaceae, bidens tripartita and xanthium sibiricum of compositae, lysimzchia fortunei of primulaceae, plantago asiatica of plantaginaceae, paulownia rawrarmii of schrophuraceae, vitex negundo of viticaceae, leonurus artemisia, perilla frutesens and salvia plebia of labitae, and commelino communis of commelinaceae are all energy plant resources.besides, pinus massoniana of pinaceae, machilus leptophylla and machilus pauhoi of lauraceae, altingia chinensis and a. gracilipes, liquidambar formosana of hammeliaceae, toxicodendron succedaeum of anacardiaceae are resin and balata plant resources. above can be show that sanqingshan has a wide variety of the wild energy plant resources. . protection of wild energy plant resources in sanqingshan . protection aim of wild energy plant resources protects the wild energy plant resources. the plant is the production of a long-term evolution and adaptation. these energy plants are the precious germplasm resources. protects the reproductive ability, in the use wild energy plant resources intensity, must consider its restoration ability and reproductive property, must give the opportunity for energy plant resources rests and builds up, enables it to restore and develop. protects the species and economic diversity. the wild energy plant resources originally are bountiful, many kinds of energy plants gather in together, forms harmony communities, when uses some resource, can not take damage other wild plant resources, development diversified management. protects the ecological habitat. when plant grows, it influence with the environment mutually, the synthesis has formed the specific ecological environment. during development use energy plant resources, must pay attention to the ecological environment which protects them to form, promotes it to restore and to develop. . protection approach of wild energy plant resources to conservation the wild energy plant resources in sanqingshan, should to take following approach: in situ conservation. as possible as to establishes different types of nature protection area. ex situ conservation. establishes some kinds of botanical gardens and the arboretums. establishes the germplasm resources storehouse. long-term preserved seed, pollen and each kind of asexual propagules. builds the raw materials base. to developed use the wild energy plant type, according to the market demand, establishes the raw materials base separately. . sustainable use of wild energy plant resources in sanqingshan . basic rules for energy plant resources use to sustainable use the wild energy plant resources in sanqingshan, should follow these rules: energy plant resources synthesis and highly effective use, in the wild energy plant uses process, will often waste the resources. should use the modern new technology, to use raw material effectively. guowen xie et al. / ieri procedia ( ) – resources productivity constant with energy plant resources used quantity. when development use energy plant resources, must first discover this area plant resources to be possible to pick the quantity, extracts the output with the most greatly economic efficiency combining site, can achieve the sustainable use. establishes the industrial base, the use and the protection develop simultaneously. including the establishment the base of wild sustainable use and the base of the manual planter, the introduction domesticates, provides stable and the high quality raw material for the industry. develops the new resources, increase the resources marketed proportion. regarding the quality is superior, but measures the plant resources, in enhances these resources outside the use factor, should seek for the new substitution resources, development the new commodity. . sustainable use plan of energy plant resources the wild energy plant resource development must achieve the protection and use develops simultaneously, the ecological benefit and the economical efficiency are unified. both will have development the use goal in the near future, and will have the long-term development direction. the plan actual content includes: direct development. to wide distribution, large amount and high economic efficiency energy plant resources, should use directly, to realize the economic efficiency as soon as possible. the near future development. to economic efficiency, but the reserve amount small wild plant resources, not immediately to form certain productivity. forward development. to those plant resources that has not verified the use, the breadth is insufficient, the processing technological level is low, creates serious resources waste, develops not eagerly. acknowledgements the authors wish to sincerely thank mr. wenbo liao and rujiang shen for their generous assistance during this study. this study was financially supported by national science foundation of china (grant no. , , ). references [ ] ragauskas a j, williams c k, davison b h, et al. the path forward for biofuels and biomaterials. science, , : . 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[ ] peng s l, liao w b, wang y y, et al. study on biodiversity of mount sanqingshan in china. beijing :science press, . using fuzzy control methods for increasing the energy efficiency of buildings | semantic scholar skip to search formskip to main content> semantic scholar's logo search sign increate free account you are currently offline. some features of the site may not work correctly. 	doi: . /ijmstr. corpus id: using fuzzy control methods for increasing the energy efficiency of buildings @article{mpelogianni usingfc, title={using fuzzy control methods for increasing the energy efficiency of buildings}, author={vassiliki mpelogianni and p. groumpos}, journal={int. j. monit. surveillance technol. res.}, year={ }, volume={ }, pages={ - } } 	vassiliki mpelogianni, p. groumpos 	published 	engineering, computer science 	int. j. monit. surveillance technol. res. the energy sector worldwide faces significant challenges that everyday become even more acute. innovative technologies and energy efficiency measures are nowadays well known and widely spread, and the main issue is to identify the more effective and reliable in the long term. in order to do so the decision maker has to compensate many factors. this article investigates the feasibility of the application of new intelligent control methods in modeling and controlling the performance of a building… expand view via publisher igi-global.com save to library create alert cite launch research feed share this paper citationsbackground citations methods citations view all topics from this paper 	fuzzy control system 	intelligent control 	fuzzy logic 	simulation 	management system 	intelligent agent citations citation type citation type 	all types 	cites results 	cites methods 	cites background has pdf publication type author more filters more filters filters sort by relevance sort by most influenced papers sort by citation count sort by recency building energy management methods based on fuzzy logic and expert intelligence 	p. groumpos, vassiliki mpelogianni, + authors amit aflalo 	computer science 	 th international conference on information, intelligence, systems and applications (iisa 	 	view excerpt, cites methods save alert research feed intelligent cost-oriented manufacturing applications to energy buildings using fuzzy experts 	g. p. peter 	engineering 	 	 save alert research feed re-approaching fuzzy cognitive maps to increase the knowledge of a system 	vassiliki mpelogianni, p. groumpos 	computer science 	ai & society 	 	 	view excerpts, cites background and methods save alert research feed grid stabilization effect of combined electricity generation from wind and photovoltaic systems in murcia, spain 	gino de jesús roa escalante, j. m. sánchez-lozano, juan-gabriel faxas, m. s. garcía-cascales, a. urbina 	computer science 	 	 save alert research feed towards a new approach of fuzzy cognitive maps 	vassiliki mpelogianni, p. groumpos 	computer science 	 th international conference on information, intelligence, systems & applications (iisa) 	 	 	view excerpt, cites methods save alert research feed intelligence and fuzzy cognitive maps: scientific issues, challenges and opportunities 	p. groumpos 	computer science 	 	 	pdf save alert research feed a revised approach in modeling fuzzy cognitive maps 	vassiliki mpelogianni, p. groumpos 	computer science 	 th mediterranean conference on control and automation (med) 	 	 save alert research feed reliability analysis for environment systems using dual hesitant fuzzy set 	a. kumar, m. ram 	computer science 	 	 save alert research feed potential benefits and current limits in the development of demand response 	clementina bruno 	business 	 	 save alert research feed references showing - of references sort byrelevance most influenced papers recency intelligent building energy management system using rule sets 	h. doukas, konstantinos d. patlitzianas, konstantinos iatropoulos, j. psarras 	engineering 	 	 	pdf save alert research feed maximum power point tracking using adaptive fuzzy logic control for grid-connected photovoltaic system 	n. patcharaprakiti, s. premrudeepreechacharn, y. sriuthaisiriwong 	engineering 	 	 	pdf save alert research feed fuzzy cognitive maps: basic theories and their application to complex systems 	p. groumpos 	computer science 	 	 save alert research feed active hebbian learning algorithm to train fuzzy cognitive maps 	e. papageorgiou, c. stylios, p. groumpos 	computer science 	int. j. approx. reason. 	 	 save alert research feed energy intelligent buildings based on user activity: a survey 	t. nguyen, m. aiello 	engineering 	 	 	pdf save alert research feed a new definition of intelligent buildings for asia 	a. so, a. c. wong, k. wong 	engineering 	 	 save alert research feed intelligent building research: a review 	j. wong, heng li, s. wang 	engineering 	 	 	 save alert research feed selection of appropriate defuzzification methods using application specific properties 	t. runkler 	mathematics, computer science 	ieee trans. fuzzy syst. 	 	 save alert research feed fuzzy cognitive map learning based on nonlinear hebbian rule 	e. papageorgiou, c. stylios, p. groumpos 	computer science 	australian conference on artificial intelligence 	 	 	pdf save alert research feed handbook of granular computing 	w. pedrycz, andrzej skowron, v. kreinovich 	computer science 	 	 	pdf save alert research feed ... ... related papers 	abstract 	topics 	 citations 	 references 	related papers stay connected with semantic scholar sign up about semantic scholar semantic scholar is a free, ai-powered research tool for scientific literature, based at the allen institute for ai. learn more → resources datasetssupp.aiapiopen corpus organization about usresearchpublishing partnersdata partners   faqcontact proudly built by ai with the help of our collaborators terms of service•privacy policy the allen institute for ai by clicking accept or continuing to use the site, you agree to the terms outlined in our privacy policy, terms of service, and dataset license accept & continue trends of risk and security problems for states and emerging strategies for coping with those trends by robert ellsworth when one considers very carefully the risk and security problems that states face today, and then looks at how states are attempting to cope with those problems, one is almost forced to the old definition of strategy as: "when you have run out of bullets, how to keep on firing." introduction we live today in an "age of peace ". what does one mean by that phrase - an age of peace? it is surely something different from the condition of having recently recovered from a war, or getting ready to fight the next war, which are the conditions that most of mankind has been in for most of history. in an age of peace, on the other hand, there is no war or prospect of war, between the major powers, of the kind which the powers maintain their main forces to fight. there have been a few periods like this in recent history: after the napoleon period, there was a wide-spread determination in europe never to let anything like that happen again. after world war i, which was rhetorically "the war to end all wars ", there was a wide-spread determination not to have any more war. ages of peace don't rule out revolutions, or wars with lesser powers, but the age of peace which we have enjoyed for about years is different. it's unique in two respects: first, in the length of time it's lasted; and secondly the intensity and the wide-spread scope of the feeling that a war between the major powers, with the strategic nuclear weapons that they maintain, is absolutely unthinkable. so that we do live in a unique age of peace. and of course the first great risk for states is the risk of the collapse of that condition. another great set of risks that we face today - as states and as peoples - is the risks that come from an apparent global shortage of material resources. the energy crisis is one example. there are a number of other examples and we will examine some of them. there is a specific risk in the build-up of military forces on the part of the soviet union. not just in the strategic nuclear realm, but also in their deployments in europe, in terms of their naval build-up and deployments, in their capabilities for projecting and exercising power beyond eurasia, and in their utiisation of modern technology. there are, in a general sense, two other kinds of risks that states face today. on the one hand, there is always the risk of being taken by surprise. in military history one is familiar with the surprises that have been visited on various states: operation barba- rossa, the german invasion of russia in june ; pearl harbour, the japanese attack on the united states in december of that year; and in the middle east the israeli attack on egypt in june and the egyptian attack on the sinai in october . also in the non-military field, states were taken quite by surprise in october by the oil embargo, and during that winter by the % increase in crude oil prices suddenly imposed by opec. what happens is that states decline to look at signs which, in retrospect, are always said to have been quite visible. states decline to see what is unpleasant for them to see, and they tend to get taken by surprise. contrarywise another risk is that states in contemplating the external world tend to exaggerate certain risks and therefore make unwise, and unnecessary concessions. for example in the case of the german re-occupation in the rheinland in the western powers exaggerated the risks of response if they offered resistance to the re-occupation of the rheinland. in , risks were exaggerated with the result that the united states conceded too much in the interim agreement covering offensive nuclear weapons, in salt i. that was corrected later at vladivostok in , but there is almost always the risk of exaggerating risks, and of making unnecessary and unwise concessions, or yielding unnecessarily, as a result. oil pricing practices let us look first at some of the specific risks involved in oil pricing practices: a problem with which all states are confronted today, not just the oil-consuming industrial states. the non-oil lesser developed countries have even worse problems coping with current oil pricing practices, and in my judgment the oil-producing states themselves have certain problems associated with the pricing practices that they are pursuing today. for the last five years the lowest inflation rates in the industrial world have been well above what had been considered unacceptably high levels of inflation during the entire post world war ii era. and then, there are the particular problems imposed on the industrial countries not just by the level of inflation, which is extremely high, but also by the fact that among different countries the rates are different. within the oecd, for example, inflation rates today range between % in some countries to as high as % in other countries. that creates very great problems in trade, monetary policy, etc. unemployment is another high-risk condition which has been exacerbated by the oil pricing practices of the world today, and i need not say to this group that inflation and unemployment together have historically been the father of confrontation and upheaval and the grand-father of war. a further very great risk stems from the fact that we are entrapped in a vicious circle. whenever recovery commences in the industrial countries, that is used as a justification by the oil producing countries to increase their prices. that of course takes the edge off the recovery, reinstitutes conditions of virulent inflation and unemploy- ment and calls forth measures to cope with those undesirable and risky conditions. it doesn't work. the world does not work today under the oil pricing practices currently being followed. here is a case where i think it's fair to say the strategies of states are largely an exercise in how to keep on firing after you have run out of bullets. no one today has any strategy for dealing directly with current oil pricing practices. of course states are trying to sell goods to the oil producers to cope with balance of payments problems, taking certain modest measures of conservation, going into debt up to their eyeballs, or doing all of the above. but essentially there is no strategy today for dealing directly with oil pricing practices as such. the reason, or one of the reasons why this is so, is that economically recoverable oil exists only in limited quantities in the earth and that within a certain number of years it will be necessary to replace oil with alternative sources of energy. and in order to develop alternatives to oil as a source of energy it is necessary that oil prices be at something like their present levels. still, there is some room for the exercise of strategy in this important area. one of the partial alternatives to oil which creates some risks is nuclear energy. in / the oil embargo and price rise gave a tremendous ifilip to the development of nuclear energy in a number of states because for them there is absolutely no option other than nuclear power as a source of electricity. that created the virtual certainty within years of very large amounts of plutonium (which is a nuclear explosive) in stockpiles all over the world in spent fuel from nuclear reactors. that - coupled with the nuclear explosion of india in may - regenerated the spectre of nuclear weapons proliferation on a world-wide basis, which was not a new concern but had been quiescent for a number of years. in addition, a number of industrial countries in the early 's had begun a spirited competition in the export of nuclear technology which must increase the risks of weapons proliferation. there is now an effort by states to develop a strategy to cope; initial steps are being taken. in many cases those steps are a little bit stumbling. for example last week, on april th, president carter made a statement in washington aimed at the elimination of plutonium from the world economy. in order to induce states to forego access to plutonium, he alluded to the possibility of the united states supplying the world with enriched fuel so that the world could avoid reprocessing and the creation of free plutonium. to put it directly: president carter has asked the world, as a part of a strategy to avoid the risks of nuclear weapons proliferation, to forego access to nuclear fuel except that which might be supplied by the u.s.a. that is not a viable basis for a widely shared or a long lasting international regime. other steps will have to be taken to develop a strategy for dealing with the problem of proliferation as the world develops nuclear energy to substitute partially for oil. global resource shortages the energy crisis, based as it is on the realization that there is a limited supply of economically recoverable oil available, is only one example of what many believe is a much wider problem: the risks of broad global resource shortages. with regard to that problem there are two conflicting views. the "catastrophists" believe that the earth's resources will soon be exhausted, and the approach of this condition will lead to the collapse of society, including the end of the age of peace to which i referred at the beginning of my remarks. the conflicting view, that of the "cornucopians ", holds that most of the earth's essential raw materials are virtually infinite and that as we exhaust one raw material we will turn to inexhaustible substitutes. according to this view we will ultimately settle into a steady state of substitution and recycling of materials. in order to bring a little perspective to these two conflicting views, it is useful to realize that % of all the molecules that we take out of the earth and use are fossil fuel. all our technological civilization, and especially our transportation, is based on an addiction to fossil fuel - an addiction that cannot be broken, or at least cannot be broken in the foreseeable future. that is a very special problem. but the minerals that we depend upon - iron, aluminium, and copper - are present in very large quantities throughout the world and at high concentrations. for those elements like mercury or silver that are not so widely present there are in fact large possibilities for substitution. therefore, the energy problem is different in degree to the extent that it is a different problem in kind. it is necessary not to confuse the two. certainly there are great risks associated with both. what are the risks? the present stage of the world, while we are using up fossil fuel at a terrific rate, may be called stage i. stage iii, i see as the age of substitutability. the risks lie in developing appropriate strategies to get from stage i to stage iii. so far the strategies that have been spoken about and attempted seem to be quite unadequate. first, it takes a long time to transition just in the case of energy: it took years to transition from wood to coal, it took about the same period to transition from coal to oil and gas. as we look at strategies for transitionning from oil and gas to something else - it seems clear that rising environmental concerns, and shortages of capital, may stretch that process even further. that risk is multiplied many times by the short time horizons of most government agencies and corporations responsible for resource policy. decision-making in corpora- tions is conditioned by interest rates which encourage indifference to costs and benefits that won't be realized within about five years. inflation further shortens the time horizon. in the case of governments, the next election prevents most policies that could return great benefits over the long term, so that governments tend to have a short time horizon. totalitarian and authoritarian governments do not seem to be doing much better, so i am not certain that the answer is the abandonment of democracy. there is no model anywhere in the world of a state dealing with the problem in a way that offers much help. what are in fact the emerging strategies? first, we see competition for access to oil. chart i the possibility of there being a balance between opec's ability and willingness to provide oil to the world on the one hand, and the needs of the oecd countries for estimated opec export levels (in million barrels a day) estimated oecd import needs (in million barrels a day) policy exports assumption imports low , high growth , medium-low , medium growth , medium-high , low growth , high , accelerated policy , source: ocd, world energy outlook, source: rustow, "foreign affairs ", april , pp , , - . , p. q. oil, on the other hand, is very slight. unless we are very lucky indeed, the figures portend in fairly clear terms a major world crisis in the early or mid 's because of the fact that there may not be enough oil from opec to satisfy the needs of the oecd countries. this alarming situation assumes zero interest on the part of the soviet union in opec oil by . that is an assumption which appears to be quite optimistic inasmuch as the soviets have their energy problem too. they are experiencing rising industrial and consumer demand for energy. they have great difficulties developing their energy resources in sibiria. they have not been able to get the capital or the technology from the west. the u.s.s.r. therefore will turn more and more to the gulf and middle east for access to that low cost and easy to extract (though not low price) oil. although the opec price is something over $ . a barrel, it costs only about cents a barrel to extract. the soviets - i expect - will need oil from the gulf and middle east by to the tune of somewhere between and million barrels a day. that will cause horrendous problems for all of us: europeans, americans, japanese, and russians. competition for access, then, is one of the strategies that has begun to emerge for dealing with the energy crisis. there are also the beginnings of another strategy for dealing with the overall global resource shortage problem, and that strategy could be called the deliberate societal shift toward placing an intrinsic value on conservation, on low material and energy growth. this, perhaps, holds out considerable hope, for two reasons. first, it is only by having a set of values that one can develop a strategy: that is in fact what a strategy is. a strategy is basically a set of values that permits one to take a longer term view of matters whatever those matters are - than would be dictated by short term tactical considerations. the emergence of a set of values, therefore, is a hopeful sign. secondly major deliberate societal shifts in values of this kind can take place quickly, have done so in the past. between and in europe a rapid and pervasive social change took place as nation after nation abandoned high rates of marital fertility and adopted contraception on a wide scale. as a result, in this short -year period there was a very great reduction in the birth rate in europe as a deliberate internalisation of a set of values and therefore of a strategy. this was rather suggested not imposed by any corporation or government. we cannot predict the future, but we can have value systems - a strategy - that will help us move from stage i to stage iii. those values would be a) conservation; efficiency and effectiveness in the transformation of raw resources into food, fertilizer, electricity, and machinery, placing a premium if you will on science and technology; cooperation instead of competition; d) steadiness of purpose; e) resilience in response to change these are some of the characteristics and qualities of a viable strategy which can help us move from stage i to stage iii without having a collapse of society, a termination of the age of peace. the russian military build-up in the meanwhile however, we are confronted with the risks of a very substantial russian build-up. for the last ten years, the soviet union has been adding between % and % a year, in real terms, to the resources devoted to military purposes. in those resources exceeded the comparable resources devoted to military purposes by the united states, and have exceeded the u.s. in every year since then. in the soviets were spending, in real terms, % more on their military than the united states. as for the future effects of present spending, the u.s.s.r. has been spending on investment account - that is to say on procurement, and research and develop- ment - at a higher rate than the overall rate, i.e. at % p.a. this broadly based and persistent build-up poses three main risks it adds fuel to the competitive fires and works against cooperation, which was one of the qualities of stage i - stage iii strategy which has been mentioned as highly desirable. because the facts of this russian military build-up are quite unpleasant to contem- plate, it may be overlooked or ignored in the wider world; that could lead to unpleasant surprises later on. or on the contrary the build-up can be exaggerated, as for example our own retired major general keegan has been exaggerating it by saying that the russians are already superior to the united states. and that exaggeration could lead - if it became widely accepted - to unnecessary and unwise concessions in various political areas. let us look for a moment at some specific aspects of the build-up. in the strategic nuclear realm, the soviets' build-up began after the cuba missile crisis of , some years ago. but one of the most intensive periods of the soviets' strategic nuclear build-up has taken place in the last years: that is, since the salt-i agreements. in that five-years period the soviets have deployed three new land-based icbm missiles and two new submarine-based ballistic missiles. all of the new missiles deployed since are equipped with multiple independently targeted re-entry vehicles (mirv's). they have high throw-weights and they have been provided with warheads with increas- ing accuracy. thus, the russians have provided themselves in the last five years with a hard-target counterforce threat to the icbm force of the united states; in addition they have under development one further land-based icbm and two further submarine- based icbm's. moreover, they have deployed the backfire bomber, and since have embarked on a very substantial programme of civil defence. the result is that, between the united states and the soviet union, as far as strategic nuclear forces are concerned, a condition of rough equivalence now obtains. (see chart ii). the chart shows trends over the last several years. it is a chart which indicates a us advantage, until about , in those static measures of the balance which are charted (it's been impossible to chart warhead accuracy): equivalent megatonnage, throw-weight, numbers of strategic nuclear delivery vehicles (which includes land-based icbm, submarine-based ballistic missiles, and strategic bombers), and numbers of war- heads. the soviet union has the advantage in in equivalent megatonnage because their land-based icbm's have high throw-weight. they have a slight advantage in strategic nuclear delivery vehicles. in numbers of warheads the united states has an advantage. what does it mean? all of these things are so abstract. it surely means something, though. one must recall, for example, the reaction of mao-tse-tung in to the russian sputnik. mao took that as meaning the soviets had missile superiority over the united states. he therefore asked khrushchev for help in standing up to the united states over quemoy and matsu. khrushchev refused, and that was one of the things which lead to the great schism between the chinese and the russians. one must also recollect the american presidential campaign of : the so-called missile gap. so, these things do have some kind of political meaning although in themselves they are quite abstract. chart ii us/ussr strategic forces advantage - - emt yield / tw throwweight sndv = stragegic nuclear delivery vehicle .f:.-... sndv warheads ent i let me also mention very briefly the united states' strategic programmes for the future: the new mobile land-based icbm, called mk; the mk a warhead which is a very high yield warhead with great accuracy. (accuracy of any kind of explosive is much more important as far as destructive effect is concerned than is yield. destructive effect varies as the / power of yield, but destructive effect of accuracy varies as the square of the distance from target.) the b-i bomber is in abeyance for the moment, the cruise missile is under development, the trident submarine is in series production as programmed all these us strategic programmes may be accelerated or held in status quo, pending the outcome of further negotiations with the soviet union over the exten- sions of the interim agreement on offensive strategic weapons, which expires october this year. the new salt proposals put forward recently in moscow by the united states were in two categories: one category was a proposal that the vladivostok accord, ballistic missile reentry vehicles, and aircraft delivered warheads warheads he' o tj i which limited both sides to strategic nuclear delivery vehicles, be reduced to treaty form and signed. that proposal was rejected by the russians. the other set of united states proposals was a very far reaching call for substantial reductions on both sides: strategic nuclear vehicles reduced from down to about , limitations on flight testing of new missiles, a ban on cruise missiles having a range in excess of km. and certain assurances with regard to deployment and utilisation of the russian backfire bomber. all these proposals were designed an intended to preserve the invulnerability of the forces of both sides, and therefore to work in the direction of technical military stability. that is to say, the technical charac- teristics of the forces of both sides would not themselves, in a time of crisis, contribute to tension because of tempting vulnerability. i do not think the soviets are interested in things like technical stability. i think the soviets look to their strategic nuclear forces for political effect. the soviets continue to be interested in the competitive political effects of having a huge and dynamic pro- gramme - just as the communities of the middle ages expressed their aspirations, their skills, their strength, through the erection of magnificent cathedrals. i myself doubt that anything like the carter proposals will be accepted by the russians for a long time - probably during the carter presidency. that poses certain risks to the world. but then the russian military build-up in europe causes certain risks also. what are those risks, and why worry about the russian build-up in europe? after all, nato does have the capability to respond adequately to a warsaw pact attack. after all, the wars in the th and early part of the th century had what numerically was the greatest military establishment in the world; there was not anything like the worry that there is today over the russian military build-up in europe. even the soviets - after the collapse of the russian army in world war i - by had rebuilt the red army so that again it was, numerically, the greatest military establish- ment in the world. yet, it was not a source of great concern. why is it a source of concern today? there are three important geo-strategic differences between the situation then and the situation now. world war ii eliminated the military strength of russia's two strongest neighbours and rivals - germany and japan. in the aftermath of world war ii there was a power vacuum on both sides of the old russian empire. as a result of world war ii, the russian military advance into eastern and central europe gave to russia for the first time in history a permanent military deployment in the very heart of central europe. moreover, the russian economy, particularly soviet military industry, was placed in intimate association with the sophisticated and advanced industrial and techno- logical potential of germany and czechoslovakia. after several decades, that has been extremely important to the russians, particularly in the fields of naval ship building, military electronics, and aircraft and missile design and construction. during most of the time since world war ii nato - the west - has relied on two advantages: . nuclear superiority, and . technological superiority. thus, although nato at present does have the capability to respond adequately to a warsaw pack attack, the balance in the future may be less secure than it has been in the past. the immediate questions facing nato - the risks - are not the old easy questions of numerical and qualitative comparisons of divisions, tanks, aircraft and the like. rather they are hard questions, risky questions: is nato prepared to respond on extremely short notice? could nato actually carry out a surge in readiness in a crisis? how capable is nato in making the transition from peace time to war time command and communications systems? how vulnerable are our theater nuclear forces? has nato adequately thought through how her forces and her governments would respond to possible soviet probes on the northern or southern flanks of europe? is nato organized to carry out such responses? the questions point to certain risks, but the real risk is that the competent nato authorities may not ask and answer those questions with sufficient rigour. the situation may put at risk certain political positions, for example in berlin. there has been in recent months a continuous pressure once again on berlin. chancelier schmidt has said he would not repay a pin-brick with a pin-brick and that is a good attitude to have. but the question is: how many pin-bricks does it take to change the four power status of berlin? western europe, all of western europe today, is characterized by weak minority governments. there is in the east a strong civil rights movement. since helsinki there has been a noticeable upsurge in so-called "helsinki-committees ", and civil rights movements, all over eastern europe, and not just in the soviet union. the combination of weakness in the west and pressures for change in the east is a risky combination. beyond europe, the soviets have developed a navy which has world-wide operating capabilities. it has a base near the indian ocean and very substantial fleet operations in the indian ocean on continuing basis. the russians are quite active in africa at the present time. they have a strong interest in the persian gulf - i have outlined that from the standpoint of the energy crisis. and there is a certain risk that the soviets may underestimate either the interests of the west, or the willingness of the west to pursue and defend those interests, due to the lassitude which has been displayed over the last years or so. i must say, however, that the french in providing some support to morocco and to zaire are demonstrating a commendable sense of a strategy for dealing with those risks outside of europe. it is a hopeful sign. conclusion what can one conclude about appropriate strategies for coping with the risks and security problems with which states are faced today? one can read almost daily in the press that the world's resources are distributed inequitably: that % of the earth's popula- tion consume % of the earth's resources after having taken them away unfairly from % of the earth's population. what is left out of that accounting is the fact that the industrious % of the world, which consumes % of the earth's resources, live in a highly evolved culture which is so far the only culture that has demonstrated a capability to efficiency and effectively transform raw resources into food, machinery, fertilizer, and electricity. without these, no part of the world can have any hope. without that high culture, and without that capability, the world would be confronted with the risk of lurching into a disintegrative anticivilization that would be reminiscent of the dark ages. of course, these issues are not new. the original walls of jericho, which were built ten thousand years ago, were built by farmers who had accumulated a surplus of grain which was the object of lustful and aggrandizing attention from desert warriors who did not have the capability of accumulating grain, and who wanted it for them- selves. that is essentially what war has been about ever since: getting somebody else's surplus, or defending your surplus against somebody who could not provide one for himself. today we are faced with a whole range of very grave risks. we are going to have to change, and more rapidly rather than slowly. we are faced not just with an oil and economics crisis, not just a social and political crisis, not just a political-military crisis. one can say that several hours are striking simultaneously on the clock of history. we must face up to the great complex crisis. we must bring to bear the best of our rich and powerful heritage: the best of our intelligence, the best of our imagination, the best of our courage. but about all what is required is a sense and spirit of conviction. it is not exactly stylish in a lecture on strategy to talk about a spirit of conviction, but that is what is required: a conviction which manifests itself in a spirit of concern and engagement. we must go beyond tactics, we must go beyond economics, we must go beyond competition. we have to be clear about a system of values. we must be unambiguous about what our values are: it is only by holding and living according to a set of values that we can have strategies for coping with the trends in risk and security with which we are confronted in the present hour. 	trends of risk and security problems for states and emerging strategies for coping with those trends 	introduction 	oil pricing practices 	global resource shortages 	the russian military build-up 	conclusion geothermal and geopressure relations as tool for petroleum exploration: abstract; textural parameters of rocks from borehold measurements and their applications in determining depositional environments: abstract; discrimination among grain-size dist... association round table age of the rocks overlying both unconformities seems to indicate slow transgressive marine overlap in the two basins. miller, betty m., u.s. geol. survey, denver, colo. geothermal and geopressure relations as tool for petroleum exploration the uinta basin represents a timely model for the study of many interesting geologic and geochemical problems that are pertinent t o current exploration re- search investigations and to technical problems con- cerning petroleum production wliich face the petro- leum industry, particularly in light of the present energy crisis. the primary areas of investigation in this reported study on the uinta basin concern the com- plexities in the exploration of ultraparaffinic crudes from fresh- and brackish-water lacustrine sedimentary deposits. an investigative study of the subsurface tempera- ture and pressure distribution patterns within the po- tentially productive section of the wasatch formation (eocene) has produced highly favorable results as an exploration tool in predicting the recent successful ex- ploratory trends within the uinta basin. a direct rela- tion has been documented between the occurrence of productive hydrocarbons within the wasatch forma- tion and the simultaneous occurrences of high geotem- peratures, abnormally high pressures, and the presence of an organic-rich shale fades. these relations currently are being investigated as a potential tool for the ex- ploration of stratigraphic traps in tertiary basins. in addition, this study illustrates an application of computer techniques to geologic evaluations on a re- gional basis: rapid data-processing methods, data banks, computer-contoured maps, and statistical analysis of geologic data. pickett, g. r., and j. l. bedwell, colorado school mines, golden, colo., and j. c. carloss, consultant, bismarck, n.d. textural parameters of rocks from borehold measurements and their ap- plications in determining depositional environments no abstract available. poole, david m., marathon research, denver, colo. discrimination among grain-size distri- butions by canonical analysis as aid to environmental interpretation grain-size analyses of sediments and sedimentary rocks have been made for many purposes. during the last to is years, grain-size analyses have been made of sands and sandstones as a means of determining their depositional environments. most of the pub- lished work on discrimination of depositional environ- ments has been based on modern sands which contain little fine material the resxilts of this work generally cannot be applied t o sandstones because of the pre- sence of considerable amounts of diagenetic silt- and clay-sized material that often is present in sandstones. in the present study, sandstones were used rather than sands. a problem that always occurs when using grain- size analyses, regardless of whether they are of sands or sandstones, is that of comparing the size distribu- tions. canonical analysis is a statistical method of com- paring grain-size distributions. the primary aim of canonical analysis is to determine numerical character- istics that best separate size distributions or determine the characteristics they have in common. in using canonical analysis, a typical or model size distribution is selected against which all the size distributions are compared. if physical theory can be applied to the choice of a reference distribution or weight function, then the results may be interpreted more easily in a physical sense. two sets of numerical values are cal- culated for each size distribution. the discriminate functions show which variable or variables, size classes in this case, are important for discrimination; and the discriminate moments show how the size distributions are related so they may be sorted and classifled. a set of characteristic roots or eigenvalues also are calcu- lated. these eigenvalues, arranged in decreasing numer- ical order, show the proportion of variation among the distributions. generally, two to three characteristic roots, each having a set of discriminate functions and moments, account for most of the variation among the size distributions. canonical analysis techniques were applied to grain-size distributions of samples from known depo- sitional environments to see if discrimination could be achieved. outcrop samples from the gallup sandstone of the san juan basin, and brushy canyon formation of the delaware basin, and core samples from the " j " formation of the denver basin were used. even though the samples contained considerable amounts (greater than %) of silt- and clay-sized material, consistent grouping of similar types of size distributions were ob- tained. it was not possible to assign, from the grain- size data alone, groups of sandstone samples to specific depositional environments. the numbers generated by canonical analysis are not unique to a particular en- vironment. however, by using the canonical analysis techniques with grain-size data combined with a knowledge of sed- imentary structures of the same samples, a geologist can obtain more information about transportation mechanisms and depositional environments than could be obtained by the use of either approach separately. reynolds, mitchell w., u.s. geol. survey, denver, colo. early campanian (cretaceous) delta- front sedimentation, south flank of wind river basin, wyoming upper cretaceous rocks of the mesaverde forma- tion, exposed between hudson and muskrat creek on the south flank of the wind river basin, accumulated in an ascending accession of delta-front, tidal-flat, and delta-plain environments. rocks of the lower two en- vironments grade east and northeast into strata de- posited in an offshore marine environment, whereas rocks of the youngest environment grade east into de- posits of a delta-front platform. during early campan- ian time, the delta-front facies accumulated across a -km-wide belt near alkali butte, repeated fluctua- tions of strand position produced interbedded units of siltstone and sandstone in the facies, and intermittent development of low-relief bars permitted accumulation of estuarine or swamp sediments across subjacent deposits of the delta front. sandstone units of the delta-front facies show an upward gradation from siltstone and sandy siltstone role of thermo - electric generator in recovery of waste heat of automobile role of thermo-electric generator in recovery of waste heat of automobile om prakash , mukesh pandey , anurag gour , savita vyas research scholar, school of energy and environmental management, utd, rgpv bhopal, mp, india assistant professor, school of energy and environmental management, utd, rgpv bhopal, mp, india assistant professor, school of energy and environmental management, utd, rgpv bhopal, mp, india , assistant professor, school of energy and environmental management, utd, rgpv bhopal, mp, india abstract: today world is facing lots of problem regarding energy crisis and thermal energy management. as we know that environmental pollution has been more emphasized heavily recently and in internal combustion engine, the engine exhaust has a tremendous amount of energy and out of total heat supplied to the engine in the form of fuel approximately - % converted into useful work and the remaining one is expelled in the form exhaust gases and this exhaust gases can be recovered by using waste heat recovery system. thermo electric principle can be used for recovering waste heat and convert into useful work by using see back effect by creating potential difference. the study shows the possible methods to recover waste heat energy from engine exhaust of an automobile and techniques to maximize energy efficiency. viewing from socio- economic perspective, as the level of energy consumption is directly proportional to the economic development and total number of population in the country, the growing rate of population in the world today indicates the energy demand is likely to increase [ ]. keywords: energy, waste heat recovery, thermo-electric generator, automobile, emissions. i. introduction today we are facing the problem of shortage of fossil fuels as well as the problem of pollution. out of all the available sources, the internal combustion engines are the major consumer of fossil fuel. in pollution. out of all the available sources, the internal combustion engines are the major consumer of fossil fuel. in pollution. out of all the available sources, the internal combustion engines coolant in the form of heat .by utilizing a portion of the lost thermal energy to change the battery instead of using an alternator the overall fuel economy can be increased by %.depending on the engine load the exhaust temperatures after the catalytic converter reach about - ºcentigrade .thermoelectric generators are small with no moving parts and they are relatively efficient at these temperatures so they are ideal for such applications . thermoelectric parts and they are relatively efficient at these temperatures so they are ideal for such applications. thermoelectric gradients [ , ]. the latest developments and technologies on waste heat recovery of exhaust gas from internal combustion engines the latest developments and technologies on waste heat recovery of exhaust gas from internal combustion engines and new developments on turbocharger technology [ ]. according to national energy conservation law and regulations for energy, consumption investigation and energy audit management. [ ] recovery activities in general order include:  identification of all energy systems  evaluation of conditions of the systems  analysis of impact of improvement to those systems need of waste heat recovery there is need of waste heat recovery because we are facing the problem of energy crisis in terms of conventional sources of energy. by using waste heat we can save not only conventional sources of energy but also we can enhance the efficiency of these sources of energy. by using waste heat we can go along with sustainable development in an easy way as it is the demand of today’s world. it is better to have something rather than having nothing and in the case of heat recovery we are saving some amount of energy which we can use not only for our self but also for upcoming generation. in general we can say that by saving waste heat we are not only securing our self but also upcoming generation from facing the problem of energy crisis which is the current issue of today’s world and it also play an important role in making india a developed country as energy plays an important role in other dimensions which are related to our economic zones. ii. methods of waste heat recovery waste heat recovery can be carried by different ways. depending upon the medium to generate electric power. heat temperature gradient electric power international journal of engineering research & technology (ijert) issn: - www.ijert.orgijertv is (this work is licensed under a creative commons attribution . international license.) vol. issue , march- fig . basic concept of a thermoelectric power generator based on sees back effect. theory and operation of thermoelectric based system is based on the phenomenon called see back effect. when a temperature difference is established between the hot and cold junctions of two dissimilar materials (metals or semiconductors) a voltage is generated, i.e., see back voltage. based on this see back effect, thermoelectric devices act as electric power generators. thermoelectric power generation have a capability to recover some exhaust heat from i.c. engine. a schematic diagram showing how the exhaust heat converted into electric power applied to an internal combustion engine using thermoelectric power generator. fig . total fuel energy content in i.c engine iii. possibility of waste heat recovery table . various engines and their output in general, diesel engines have an efficiency of about % and thus the rest of the input energy is wasted. despite recent improvements of diesel engine efficiency, a considerable amount of energy is still expelled to the ambient with the exhaust gas. in a water-cooled engine about kw and - % of the input energy is wasted in the coolant and exhaust gases respectively. the amount of such loss, recoverable at least partly, greatly depends on the engine load. mr. johnson found that for a typical . l engine with a maximum output power of kw, the total waste heat dissipated can vary from kw to as much as kw across the range of usual engine operation. it is suggested that for a typical and representative driving cycle, the average heating power available from waste heat is about kw, compared to . – . kw of cooling capacity provided by typical passenger car vcr systems [ ]. since, the wasted energy represents about two-thirds of the input energy. table- this temperature can be taken from various surveys. availability of waste heat from i.c. engine: the quantity of waste heat contained in a exhaust gas is a function of both the temperature and the mass flow rate of the exhaust gas: international journal of engineering research & technology (ijert) issn: - www.ijert.orgijertv is (this work is licensed under a creative commons attribution . international license.) vol. issue , march- where, q is the heat loss (kj/min); is the exhaust gas mass flow rate (kg/min); is the specific heat of exhaust gas (kj/kg°k); and is temperature gradient in °k. in order to enable heat transfer and recovery, it is necessary that the waste heat source temperature is higher than the heat sink temperature. moreover, the magnitude of the temperature difference between the heat source and sink is an important determinant of waste heat’s utility or “quality”. the source and sink temperature difference influences the rate at which heat is transferred per unit surface area of recovery system, and the maximum theoretical efficiency of converting thermal from the heat source to another form of energy (i.e., mechanical or electrical). finally, the temperature range has important function for the selection of waste heat recovery system designs [ , ]. fig. methodology of arrangement of teg thermoelectric devices may potentially produce twice the efficiency as compared to other technologies in the current market [ ]. by using this methodology we can convert waste exhaust gases into electric power. in this the exhaust gases in the pipe provide the heat source to the thermoelectric generator, whereas the sink provided by circulation of cooling water. thermoelectric material- they are divided into three groupings based on temperature ranges:-  alloy based on bismuth in combination with antinomy, tellurium and selenium (low temperature material used up to k).  based on alloy of lead (intermediate temperature materials used up to k).  fabricated from silicon-germanium alloy (high temperature materials up to k). fig. a thermoelectric module. fig. diagram of tem sandwiched between hot plate and cold plate. table- shows the thermal properties of the alloys. so it’s shows to use aluminium to make plates. international journal of engineering research & technology (ijert) issn: - www.ijert.orgijertv is (this work is licensed under a creative commons attribution . international license.) vol. issue , march- fig. shows temperature ranges for thermoelectric material [ ]. a single thermoelectric couple is constructed from two ‘pellets ‘of semiconductor material usually made from bismuth telluride (bi te ). one of these pellets is doped with acceptor impurity to create a p-type pellet; the other is doped with donor impurity to produce an n-type pellet. the two pellets are physically linked together on one side, usually with a small of copper, and mounted between two ceramic outer plates that provide electrical isolation and structural integrity. for thermoelectric power generation, if a temperature difference is maintained between two sides of the thermoelectric couple, thermal energy will move through the device with this heat and an electrical voltage, called the see beck voltage, will be created. if a resistive load is connected across the thermoelectric couple’s output terminals, electrical current will flow in the load and a voltage will be generated at the load. practical thermoelectric modules are constructed with several of these thermoelectric couples connected electrically in series and thermally in parallel. standard thermoelectric modules typically contain a minimum of three couples, rising to one hundred and twenty seven couples for larger devices. a schematic diagram of a single thermoelectric couple connected for thermoelectric power generation and a side view of a thermoelectric module. as we know that temperature of pipe surfaces of exhaust gases is very high near about - ºc. so a heat exchanger is made which conducts heat from exhaust pipe to thermoelectric modules. iv. result and discussion as we know that thermoelectric material low efficient material therefore the major drawback of thermoelectric power generator is their relatively low conversion efficiency but thermoelectric power generators have many advantages like they require less maintenance; they are simple, compact and safe; they are environmentally friendly; they are flexible power sources; they have very small size. through thermoelectric generators the amount of power which we get is from the waste heat. in other words we can say that we are saving some heat from getting waste and it is better to have something rather than having nothing. there are several ways to increase the amount of power-  if we increase the no. of modules we would able to produce more power depending upon hot side temperature.  thermoelectric power generator gives maximum power of near about . to . watt as the hot side temperature was low near about ºc but if we increase hot side temperature to near about ºc we can get . watt of power. so this project emphasizes on the importance of thermoelectric generators in the present scenario as a power saving and maintaining ecological balance tool. technology would be able to improve the efficiency of the thermoelectric generators and we should work for improving the temperature of the hot side so that we would get more power. this technology will be beneficial for india as we are facing the problem of shortage of fossil fuels and problem of global warming. refrences [ ] basel i. ismail, wael h. ahmed, , “thermoelectric power generation using waste-heat energy as an alternative green technology,” recent patents on electrical engineering, , pp. - . [ ] k.t. zorbas, e. hatzikraniotis, and k.m. paraskevopoulos; power and efficiency calculation in commercial teg and application in wasted heat recovery in automobile, physics department, aristotle university of thessaloniki, greece. [ ] nyambayar baatar, shiho kim; a thermoelectric generator replacing radiator for internal combustion engine vehicles, telkomnika, vol. , no. , december , pp. ~ , issn: - . [ ] sumeet kumar, stephen d. heister, xianfan xu, james r. salvador, and gregory p. meisner, , “thermoelectric generators for automotive waste heat recovery systems part i: numerical modeling and baseline model analysis,” journal of electronic materials, doi: . /s - - - , tms. [ ] jian, zhang yuchen, chen song, gong suzhou; “how to reduce energy consumption by energy audits and energy management” issue date: july - aug. on page(s): - date of current version: september . [ ] v. johnson, “heat-generated cooling opportunities in vehicles,” sae technical papers, no. , - - . [ ] m. hatazawa, “performance of a thermo acoustic sound wave generator driven with waste heat of automobile gasoline engine,” transactions of the japan society of mechanical engineers ( ) ( ) – . [ ] diego a. arias, timothy a. shedd, ryan k. jester, “theoretical analysis of waste heat recovery from an internal combustion engine in a hybrid vehicle,” sae paper - - . [ ] zhang x, chau kt, “an automotive thermoelectric–photovoltaic hybrid energy system using maximum power point tracking,” energy conversion and management ; ( ): – . [ ] [ ] francis stabler , ‘automotive thermoelectric generator design issues’, doe thermoelectric applications workshop. international journal of engineering research & technology (ijert) issn: - www.ijert.orgijertv is (this work is licensed under a creative commons attribution . international license.) vol. issue , march- wp-p m- .ebi.ac.uk params is empty sys_ exception wp-p m- .ebi.ac.uk no params is empty exception params is empty / / - : : if (typeof jquery === "undefined") document.write('[script type="text/javascript" src="/corehtml/pmc/jig/ . . /js/jig.min.js"][/script]'.replace(/\[/g,string.fromcharcode( )).replace(/\]/g,string.fromcharcode( ))); // // // window.name="mainwindow"; .pmc-wm {background:transparent repeat-y top left;background-image:url(/corehtml/pmc/pmcgifs/wm-nobrand.png);background-size: auto, contain} .print-view{display:block} page not available reason: the web page address (url) that you used may be incorrect. message id: (wp-p m- .ebi.ac.uk) time: / / : : if you need further help, please send an email to pmc. include the information from the box above in your message. otherwise, click on one of the following links to continue using pmc: search the complete pmc archive. browse the contents of a specific journal in pmc. find a specific article by its citation (journal, date, volume, first page, author or article title). http://europepmc.org/abstract/med/ industrial microalgae: do not shoot ahead! oatao is an open access repository that collects the work of toulouse researchers and makes it freely available over the web where possible any correspondence concerning this service should be sent to the repository administrator: tech-oatao@listes-diff.inp-toulouse.fr this is an author’s version published in: http://oatao.univ-toulouse.fr/ to cite this version: vaca-garcia, carlos industrial microalgae: do not shoot ahead! ( ) biofuels, bioproducts and biorefining, ( ). - . issn - x official url: https://doi.org/ . /bbb. mailto:tech-oatao@listes-diff.inp-toulouse.fr http://www.idref.fr/ industrial microalgae: do not shoot ahead! author info: professor carlos vaca-garcia, national polytechnic institute of toulouse, france coordinator of the algoraffinerie french consortium. contact: carlos vaca garcia [carlos.vacagarcia@ensiacet.fr] convincing the public that the ‘ microalgae miracle’ is right here can ultimately be detrimental to this extraordinarily promising industry i n the present energy crisis, microalgae seem to be a new eldorado. th ey can produce biofuel as they consume co . th ere is a big risk in promising too much, however, because the production of energy from microalgae has not yet been demonstrated to be economically realistic, at least in a free market. many technological challenges still remain and there are serious doubts about the availability of algal fuel on a large scale in the next few years. we have to be cautious about the spectacular announcements of the economical attractiveness or the potential energy yield of these cells. th ere are oft en articles in the mass media talking about miraculous solutions to the energy situation promising such unrealistic yields that even the laws of thermodynamics are blasted out. but let’s remind ourselves that the photosynthetic conversion of energy can create a theoretical maximum of about metric tons of biomass per hectare per year with intertropical solar radiation. in practice, it is as low as × kg.ha- .yr- ( ton.ac- .yr- ) in most european countries or in the usa. indeed, microalgae are a new type of biomass for new industrial applications. but we also have to consider their other applications: answering to essential nutritional needs and playing the role of pre-purifi ed feedstock for the production of active molecules aimed at drugs and cosmetics. all this comes in addition to the original energy purposes. a systemic approach to the culture and refi nery of microalgae is therefore essential. th is approach should integrate the production of biofuels and by-products to invest in other outlets: such as the applications this communication is co-signed by jean jenck, olivier lepine, claude gudin (algosource technologies), jean-jacques caboche (f&m, italie), jack legrand, jérémy pruvost (gepea st-nazaire), gilles peltier, laurent cournac (cea), jean-françois cornet, gilles dussap (lgcb clermont-ferrand). already mentioned and even new ones, such as biomaterials and organic frames for nanostructures. we have to avoid a deadlock and avoid the diffi culties we saw with the fi rst generation of biofuels due to their competition with food resources. convincing the public that the ‘microalgae miracle’ is right here can ultimately be detrimental to this extraordinarily promising industry. let’s protect it. th e best of the years are yet to come. carlos vaca-garcia doi: . /bbb. biodiesel production from algae to overcome the energy crisis ble at sciencedirect hayati journal of biosciences ( ) e contents lists availa h o s t e d by hayati journal of biosciences journal homepage: http://www.journals.elsevier.com/ hayati-journal-of-biosciences review article biodiesel production from algae to overcome the energy crisis suliman khan, rabeea siddique, wasim sajjad, ghulam nabi, khizar mian hayat, pengfei duan, lunguang yao * the key laboratory of aquatic biodiversity and conservation of chinese academy of sciences, institute of hydrobiology, chinese academy of sciences, wuhan, hubei , china. department of biomedical engineering, huazhong university of science and technology, wuhan , pr china. key laboratory of petroleum resources, gansu province/key laboratory of petroleum resources research, institute of geology and geophysics, chinese academy of sciences, lanzhou , pr china. moe key laboratory of cell activities and stress adaptations, school of life sciences, lanzhou university, lanzhou , pr china. collaborative innovation center of water security for water source region of mid-line of south-to-north diversion project, college of agricultural engineering, nanyang normal university, henan, china. a r t i c l e i n f o article history: received january received in revised form october accepted october available online november keywords: algae, biofuel, fossil fuel, gene * corresponding author. peer review under responsibility of institut perta https://doi.org/ . /j.hjb. . . - /copyright © institut pertanian bogo creativecommons.org/licenses/by-nc-nd/ . /). a b s t r a c t the use of energy sources has reached at the level that whole world is relying on it. being the major source of energy, fuels are considered the most important. the fear of diminishing the available sources thirst towards biofuel production has increased during last decades. considering the food problems, algae gain the most attention to be used as biofuel producers. the use of crop and food-producing plants will never be a best fit into the priorities for biofuel production as they will disturb the food needs. different types of algae having the different production abilities. normally algae have %e % oil contents that could be converted into different types of fuels such as kerosene oil and biodiesel. the diesel production from algae is economical and easy. different species such as tribonema, ulothrix and euglena have good potential for biodiesel production. gene technology can be used to enhance the production of oil and biodiesel contents and stability of algae. by increasing the genetic expressions, we can find the ways to achieve the required biofuel amounts easily and continuously to overcome the fuels deficiency. the present review article focusses on the role of algae as a possible substitute for fossil fuel as an ideal biofuel reactant. copyright © institut pertanian bogor. production and hosting by elsevier b.v. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). . introduction energy crisis is among the biggest problems, leading the world to be unsafe and non-peaceful. the demand is increasing day by day. the available resources are rapidly decreasing and indication is, soon will be vanished. in such situations, more attention is needed to be given towards renewable energy sources. fossil fuels are used on a large scale in the world, but unsustainable because they in- crease co level and accumulate greenhouse gases which make the environment unhealthy. to keep the environment clean and maintain sustainability, renewable and environmentally friendly fuels are needed to be produced (schenk, ). biofuels are defined as the liquid fuels produced from the biomass of different agricultural and forest products and biodegradable portion of nian bogor. r. production and hosting by els industrial waste (dufey, ). biodiesel is extracted from vege- table oils (shay, ), biobutanol (dürre, ), jatropha curcas (becker and makkar, ) and algae (roessler et al., ; sawayama et al., ; dunahay et al., ; sheehan et al., ). brazil, the united states and the european union are the world's largest biodiesel producers (balat ). biofuel production has been estimated to be billion litres (o european commission, ). the algae are now becoming the main source of biofuel production in the world. they are considered as the safer, non-competitive and rapidly growing organisms among those could be used for biodiesel production. they have the abilities to grow without much care on waste nutrients (roberts, ), and are considered the better source of biodiesel production as other sources can cause food problems as they are mainly including those plants which are used for food (patil et al., ). moreover, evier b.v. this is an open access article under the cc by-nc-nd license (http:// http://creativecommons.org/licenses/by-nc-nd/ . / http://crossmark.crossref.org/dialog/?doi= . /j.hjb. . . &domain=pdf www.sciencedirect.com/science/journal/ https://doi.org/ . /j.hjb. . . http://creativecommons.org/licenses/by-nc-nd/ . / http://creativecommons.org/licenses/by-nc-nd/ . / https://doi.org/ . /j.hjb. . . https://doi.org/ . /j.hjb. . . s. khan, et al biodiesel contents of crops are less sustainable and less in quantity as compared with algae (charles et al., ). algae have around % energy content to that contained by petroleum (chisti, , ). algal cells have % lipid content (lam and lee, ), which is higher than other sources including soybeans and palm oils (lam and lee, ; kligerman and bouwer, ). microalgae have %e % lipid contents by dry weight and this value raises to %. botryococcus braunii is a microalga which is having %e % hydrocarbon content which can be extracted easily (mirza et al., ). algae can efficiently remove the toxic components from water, so playing a role in waste water treatment. their remediating role in waste water treatment and rich sources of biodiesel make them suitable sources to be grown on large scale (pittman et al., ; kligerman and bouwer, ). micro as well as macro algae can be cultivated on large scale in short period. micro algae are photosynthetic and heterotrophic having the potential to be grown as energy crops. they have the ability to produce certain economically important compounds including fats and oils (rawat et al. ; pittman et al. ). algal biofuel does not have harmful chemicals, so environment can be kept clean after the combustion. pakistan state oil has currently started work on biodiesel pro- duction and successfully cultivated j. curcas plant to produce bio- diesel. drying needs energy in the case of crops and food-producing plants; but in the case of algae, it is economical to dry them with sun light. thermo chemical drying process is also easy in algae in comparison with other plants (banerjee et al. ; tsukahara and sawayama, ). biomass is treated with anaerobic microorgan- isms to produce biogas which is having high content of methane, so it can be used as an alternate source of energy (mes et al. ). algae cells have the bio fuel contents inside the cells, and the cell wall retains these components intact, so the cell wall must be broken; and in most cases, anaerobic digestion is preferred, which is the most prominent method of extracting these components figure . this figure illustrates the general process of biodiesel production from algae on sm algal species for the oil contents. dotted arrow indicates the addition to specific steps whi from the cells (reith, ). the algae with high biofuel contents and easily cultivatable are preferred. the objective of this review article was to critically describe various aspects of algae as an ideal target for biofuel productions. . the processes for biofuel production using algae algae have oil contents with different compositions depending on the specie types. some species were identified that they have good fatty acid values. in the same way, some algae have more components of fatty acids by their dry masses. micro algae can grow in different conditions even in availability of fewer nutrients. they are best to be chosen for cultivation. the collection of sample needs care so that the whole biofuel contents could be obtained through careful handling of the instruments. the growth is also affected by different environmental factors which are not specif- ically known for every region, so the process needs careful atten- tion accordingly (richmond, ). the simple method of fatty acids extraction and separation of biodiesel is the blending method on small or experimental scale. this process consists of several steps which have been shown in figure . it is also necessary to know about the cultivation unit of the algal cultivation, whether it is good to choose the closed system or open system. the process either batch or continuous is confirmed depending on the conditions and facilities, including ph, temper- ature, type of algal specie and the amount of algal biomass (kaewpintong, ; chojnacka and marquez-rocha, ; chojnacka et al. ). harvesting techniques are finalized based on the location and conditions (grima et al. ). most favourable harvesting techniques suggested are based on settling pond or sedimentation tank. density and moisture adjustment is required during the whole process of biodiesel production. the drying technique mostly used is spray drying, drum drying was also all scale and for experimental purpose. this method could be used to compare different ch have been highlighted with bold letters and full lined arrows. biodiesel to overcome the energy crisis suggested. the disruption process through mechanical handlings is considered the most favourable. the other requirements are the use of solvents such as hexane and ethanol are required for active process. ultrasound and microwave-based extraction methods can also be of benefit if other sources are not available (richmond, ). . cultivation systems two main cultivation systems are open system and closed sys- tem. the open system is normally a pond system, where the algae can grow naturally or their growth can be enhanced with human interactions. according to kaewpintong ( ), closed system is preferred as the process is easy and energy saving along with least chances of the interference by environmental factors. also, the factors and nutrients can be controlled easily in the closed system; but in some cases, the open system gains priority. in a study regarding algae production, ugwu ( ) concluded that algae could be grown either in open culture systems or closed systems, but on larger scale production open system is preferred. open system does not require the huge amount of energy and man po- wer, and also economical. open system cultivation also helps in the treatment of waste water sources, and the production process continues without disruptions. open ponds are easy to construct and operate. however, major limitations in open ponds include poor light utilization by the cells, evaporative losses, diffusion of co to the atmosphere and requirement of large areas of land. the closed system has some advantages over open system. in closed systems (photo bioreactors), higher biomass products are obtained, and contamination can easily be prevented. because of these ad- vantages, the closed system also obtains attention. besides these major systems, the other cultivation systems or methods include water stabilization pond, advanced integrated waste water pond system and algal high-rate ponds. cost-effec- tiveness, larger production, commercial scale growth, minimization of sludge accumulation, low energy demands, well suited for tropical and subtropical countries and removal of biological oxygen demand (bod) are some of the advantages these systems have, but they also have some serious disadvantages, including light pene- tration limitation, windy weather disruptions, hard to take care and the chances of destroying are higher (kligerman and bouwer, ). . comparative analysis of algal growth and their oil contents production mitsuo et al. ( ) worked on spirulina, which is a blue-green alga. they developed the cultivation method of this alga in the closed system. they were developing this method to sue this algal specie for space. this development was beneficial to keep the conditions for growing of algae homogenous. this was a good step to obtain the products of algae. the system was made in such a way the carbon dioxide and oxygen control was made beneficial. moreover, by the separation of algae and biomass, product isolation was made easy. leghari ( ) carried out the ecological study of algal flora of the jhelum river in azad kashmir during the period of january to june . this included the research on species, belonging to genera from seven groups of algae. the basic idea of the study was to assess the population of this algal flora as they play an important role in a balanced ecological system. water pollution has increased the population of the flora to dangerously high levels, inducing oxygen-depletion in water, which unbalances the ecosystem as is hazardous for aquatic life. scarcity of such plants may also be dangerous as they are the primary producers and their scarcity may unbalance the aquatic food chain. thus, for a balanced ecosystem, a balanced population of the algal flora is necessary. leghari ( ) carried out the comparative ecological study of algal genera and useful aquatic weeds of various localities. twenty-nine genera of algae belonging to five classes, aquatic weeds belonging to families of five groups and physicochemical parameters were recorded. lakes are rich in primary productivity and fish production. the study revealed to search the algal flora and aquatic weeds, water analysis to observe physicochemical proper- ties, comparative study to explore species either rare or common to observe and are beneficial or toxic in use. ali ( ) reviewed the limnological studies, keeping in view their strong impact on wetland’s biodiversity. the results revealed that among total species of planktons, were found in uchalli, in khabbaki and in jahalar lake, and % species were phytoplankton, whereas % were zooplankton. chisti ( ) revealed that because of the higher photosynthetic efficiency of algae, higher biomass productivities, a faster growth rate than higher plants (which was also important in the screening step), highest co fixation and o production, growing in liquid medium which can be handled easily, algae can be grown in variable cli- mates and non-arable land including marginal areas unsuitable for agricultural purposes (e.g. desert and seashore lands), in non- potable water or even as a waste treatment purpose, use far less water than traditional crops and do not displace food crop cultures; their production is not seasonal and can be harvested daily. fernandez et al. ( ) studied viability of marine algae as a source of renewable energy to laboratory scale. they evaluated the anaerobic digestion of macrocystis pyrifera, durvillaea antarctica and their blend : (w/w) in a two-phase system and observed methane in biogas yield of algae blend, but a lower biogas yield was obtained. they concluded that methane could be produced in a two-phase digestion system using either algae species or their blend. mirza et al. ( ) discussed that attention had been given to the use of municipal and industrial wastes for power generation. the government had been financing many projects related to biomass energy development in the country, but still lot more ef- forts were being needed for harnessing full potential and taking maximum benefit out of this important renewable energy resource. gouveia ( ) investigated the screening of microalgae (chlorella vulgaris, spirulina maxima, nannochloropsis sp., neochloris oleoabundans, scenedesmus obliquus and dunaliella tertiolecta), which was performed to choose the best one(s), in terms of quantity and quality as oil source for biofuel production. n. oleoa- bundans (fresh water microalga) and nannochloropsis sp. (marine microalga) proved to be suitable as raw materials for biofuel production because of their high oil content ( . % and . %, respectively). both microalgae, when grown under nitrogen shortage, showed a great increase (» %) in oil quantity. if the purpose is to produce biodiesel only from one species, s. obliquus presents the most adequate fatty acid profile, namely in terms of linolenic and other polyunsaturated fatty acids. however, the microalgae n. oleoabundans, nannochloropsis sp. and d. tertiolecta can also be used if associated with other micro algal oils and vegetable oils. sharif et al. ( ) studied the common species oedogonium and spirogyra to compare the amount of biodiesel production. algal oil and biodiesel (ester) production was higher in oedogonium than spirogyra sp. however, biomass (after oil extrac- tion) was higher in spirogyra than oedogonium sp. sediments (glycerin, water and pigments) were also higher in spirogyra than oedogonium sp. there was no difference of ph between spirogyra and oedogonium specie. these results indicate that biodiesel can be produced from both species and oedogonium is better source than spirogyra specie. park et al. ( ) reported that algae could use growth nutrients such as nitrogen and phosphorous from a variety of wastewater sources (agricultural run-off, concentrated animal feed s. khan, et al operations and industrial and municipal wastewater), thus providing a sustainable bioremediation of these waste water for economic benefits). prem et al. ( ) reviewed that worldwide, many nations impose blending of their transport fuels with biofuels, approxi- mating % globally by , to contribute to energy security while reducing emission of greenhouse gases. pienkos and darzins ( ) concluded that the comparison of one unique aspect of algae with other advanced feedstock was the spectrum of species available for amenability for biofuel production. various species may be selected to optimize the production of different biofuels. algae offer a diverse spectrum of valuable products and pollution solutions such as food, nutritional compounds, animal feed, energy sources (including jet fuel, aviation gas, biodiesel, gasoline and bioethanol), organic fertilizers, biodegradable plastics, recombinant proteins, pigments, medicines, pharmaceuticals and vaccines. a number of microorganisms belonging to the genera of algae, yeast, bacteria and fungi have ability to accumulate neutral lipids under specific cultivation conditions. the microbial lipids contained high fractions of polyunsaturated fatty acids and had the potential to serve as a source of significant quantities of transportation fuels (liam and owende, ). subhadra and edwards ( ) studied that algal biomass provided viable third generation feedstock for liquid transportation fuel that does not compete with food crops for cropland. however, fossil energy inputs and intensive water usage diminishes the positive aspects of algal energy production. an in- tegrated renewable energy park approach was proposed for aligning renewable energy industries in resource-specific regions in the united states for synergistic electricity and liquid biofuel production from algal biomass with net zero carbon emissions. . role of gene technologies in biodiesel production genomics can play a key role in solving the world energy crisis. through genomics, scientists can develop a better approach of how to harness various renewable sources of energy, such as cyanobacteria, microalgae and lignocellulosic biomass. one day on a global scale, the development of sustainable biofuel through genetic engineering of an enzyme will replace fossil fuels (davidson, ). cellulose biomass has the capability to meet the demand for liquid fuel, but for high-scale deployment of biomass- to-biofuel technologies, process inefficiencies and land-use requirements are the main obstacles. thus, the genomics knowl- edge of microorganisms can break down the biomass, and po- tential energy crops will be vital for improving the prospects of important cellulosic biofuel production (rubin, ). the genomic information of bioenergy crops will also accelerate the domestication of these plants, and even will improve their growth on poor agricultural lands to avoid competition with other food crops (rubin, ). further genetic underpinning, such as cell wall chemistry, stem thickness, branching habit, competition for light and growth rates, will maximize biomass yield per unit land area (tuskan et al. ; rubin, ). currently, intensive global researches, for increasing and modifying the accumulation of energy rich compounds, such as polysaccharides, hydrocarbons, alcohols, lipids and other energy rich chemical compounds in photosynthetic organisms, bacteria and yeast via genetic engi- neering have been carried out with good results. although many advances through genetic engineering in photosynthetic micro- organisms have been achieved, because of their capability to secrete or store energy-rich hydrocarbons, superior growth rates, diverse metabolic abilities and high photosynthetic conversion efficiencies (radakovits et al., ). still, further studies are needed to extend these advances to industrially relevant microorganisms. . conclusion although much work has been performed, identification of suitable specie having good characteristics not only production wise but also growth wise is needed. the growth of algae needs suitable environment, and work on its cultivation and harvesting is needed to be developed that a large amount could be grown. technical experience and technological development are also required. more advancement in genetically engineering species growth is needed to produce required amounts of biodiesel in short time and less energy utilization. conflict of interest statement the authors declare that there is no conflict of interest regarding the publication of this paper. acknowledgement the authors are thankful to cas-twas president's fellowship program and state key laboratory of freshwater ecology and biotechnology (grant no. y f ) for financial support. references ali z, ahmad ss, akhtar m, khan ma, khan mn. . ecology and diversity of planktons in lakes of uchalli wetlands complex. pak j anim plt sci : e . balat m. . an overview of biofuels and policies in the european union. energy sources b econ plann ( ): e . banerjee a, sharma r, chisti y, banerjee uc. . botryococcus braunii a renew- able source of hydrocarbons and other chemicals. crit. 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( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref http://refhub.elsevier.com/s - ( ) - /sref 	biodiesel production from algae to overcome the energy crisis 	 . introduction 	 . the processes for biofuel production using algae 	 . cultivation systems 	 . comparative analysis of algal growth and their oil contents production 	 . role of gene technologies in biodiesel production 	 . conclusion 	conflict of interest statement 	acknowledgement 	references epl_ .qxd nowadays most of the synthetic polymers are derived from non-renewable fossil oil. environ- mental pollution has to be inevitably generated dur- ing their production. besides, discards of the end- products are hard to be degraded. for keeping in step with societal concerns on energy crisis and ecological problems, reduction in the usage of petrol-based materials becomes more and more important. as a result, natural polymers are receiv- ing increasing attention. since the traditional natural polymers (e.g., silk, rubber, etc.) cannot meet the tremendous needs of application in terms of species or properties, great efforts have to be continuously made to develop new polymers from natural resources. compared to the non-degradable polymers from renewable resources, the materials that emulate the perform- ance of petrol-based polymers while keeping bio- degradability seem to be more promising. in fact, bio-based polymers have been under inves- tigation for many years. both chemical and micro- bial approaches proved to be feasible to convert natural substances. the successful examples in this aspect are cellulose plastics (from cotton, woods, etc.), polylactide (pla, from corn, sugarcane, etc.), polyhydroxyalkanoate (pha, from glucose), starch plastics and soybean plastics, etc. as mentioned above, however, many biodegrad- able polymers are based on food and feed, which are not cost-effective enough at present. their applications have to be confined to some specific areas with high added value. in this context, manu- facturing affordable and fully biodegradable poly- mers from annually renewable resources except food and feed coupled with low-cost processing techniques are critical. attempts in this direction have been started, like plasticized wood sawdust, plant fibers reinforced plasticized wood sawdust, plasticized plant fibers, etc. although achievements in the field of green poly- mers are far from satisfactory, the new opportuni- ties that were found during research and develop- ment have demonstrated it is a challenging job to invent new species with balanced performance. interdisciplinary studies based on tight collabora- tion among scientists and governmental supports are prerequisites for overcoming the difficulties. moreover, enterprises should be actively involved because they will gain benefit from production and usage of these new materials in the long term. *corresponding author, e-mail: ceszmq@mail.sysu.edu.cn © bme-pt and gte editorial corner – a personal view polymeric materials from natural resources – emerging as the times require m. q. zhang* materials science institute, zhongshan university, guangzhou , p. r. china express polymer letters vol. , no. ( ) available online at www.expresspolymlett.com doi: . /expresspolymlett. . prof. dr. ming qiu zhang member of international advisory board power crisis and the corresponding strategies available online at www.sciencedirect.com energy procedia ( ) – – © published by elsevier ltd. doi: . /j.egypro. . . iaceed power crisis and the corresponding strategies li yanbin, wang qingzhuang , chen xiaojie north china electric power university, beijing, abstract power crisis today contains not only the p henomenal of p ower storage, but also the p roblem of env ironment p ollution caused by electric p ower industry . china has exp erienced fast develop ment in the p ast y ears and cor resp ondingly , p eop le’s livin g level is high er than the p ast . as a result, with the fast develop ment of economy , the p eop le’s demand on energy and p ower is more and larger than the p ast . in p ractice, although the burden of p ower supp ly has released in certain degr ee via buildin g more p ower stations, p ower crisis is still in existence because of the flaw in electricity industry structure and technique asp ects. in the p ap er, we analy ze national stage of china in electricity industry asp ect, and then we p rovide two typ ical cases about power crisis and cop ing strategies. finally , we p resent relevant p olicies and strategies to tackle with the corresp onding p roblem of china p ower crisis. keywords: power crisis; power installed capacity; renewable energy . introduction in st century, all countries are facing the challenge of energy. power crisis is one of the greatest crises in energy. many experts and scholars have researched in energy policies to against electric energy crisis. engineering education in general and power engineering education in particular is discussed by jorge. f. dopazo and alberto m. sasson ( )[ ]. h.l. zhou [ ] and j.x. liu[ ] had researched wind power industry. grid-connected pv systems are researched by muhammad qua mruzza man and kari mujibur rah man ( )[ ]. u.a. korde had researched ocean wave in his paper ( )[ ]. shi yongqian had talked about nuclear power in h is paper [ ]. the corresponding strategies to against electric energy crisis will be researched in the future. in th is paper, many strategies have been given. it contains wang qingzhuang. tel.: e-m ail address: wqzhuang@yeah.net. open access under cc by-nc-nd license. © published by elsevier ltd. selection and peer-review under responsibility of riuds open access under cc by-nc-nd license. http://creativecommons.org/licenses/by-nc-nd/ . / http://creativecommons.org/licenses/by-nc-nd/ . / li yanbin et al. / energy procedia ( ) – structural strategic adjustment of powe r industry, designing more reasonable grid layout, constructing new power plant, renewable energy construction, developing intelligent power grid and so on. . current situation of electric power industry in china as it is shown, the proportion of thermal powe r in national installed capacity is further higher than other energy power. wind power and nuclear powe r doesn’t reach % of the total installed capacity. as we a ll know, the main material to p roduce therma l power is coa l which wou ld let out large a mount of carbon dio xide and su lphur dio xide. according to statistics of , ch inese power industry’ herfindahl-type of inde x is . . in china, the central government ma kes all kinds of relative plans of the development of power industry. however, power technology of china is further behind of developed countries. in , each kwh e lectric power needs fuel g coal in china, which is higher g than american. furthermore, in western china, there is enough energy, espe cially hydro energy. northeast of china has little energy, but in these places, the power consumption is large. tabl e . s tatistics of power installed capacity in c hina, - [ ] . case analys is . . california's failure case in s, a merica power industry was still trad itional public utilit ies. in o rder to improve enterprise’ yielding and operational effic iency, states successively introduce relative regulations to encourage independent power plants to construct new power plants.. after s, a merican energy e xperience fast development. natural gas and coal are the main raw materia ls of power generation. their prices are consistently down. because public utility co mpanies and independent power plants signed long-term contract, public utility companies faced heavy losses. reform polic ies of the federal energy regulatory commission and california government: first, the federa l energy regulatory co mmission ’s allo wed public utility co mpanies re move contract with independent power plants and compensated precipitation cost to independent power plants. second, commission considered that spot trading is the best way to keep effectiveness of market and banned forward transaction. california ’ power crises [ ]. . . success case of japan to coping with power crises in the past second world war, japan had e xperienced twice power crises . the first crisis was happened in the period of japan economy soaring. in the period of - , average growth rate of gdp of japan was high to %. ho wever, powe r supply couldn’t follow the step of economy development. the second power crisis was happened under the background of twice oil c risis . positive measures of japanese government: for the first power crises , the government of japan main ly resorted to policy of developing electric ity, put power industry on the core position of energy industry and adjusted structure of energy. for the second power crises the japanese government adopted comprehensive energy policy that considers economic development and environmental protection. therm al power hydropower wind power nuclear power the total . . . . . . . . . . . . . . . li yanbin et al. / energy procedia ( ) – . china’s corresponding s trategies and policies . . institutional reform in electricity mark et first, china’s government should promu lgate reform laws to c lear the direction of re form and the status of the power industry and set up technical indicators to track and predict the feasibility of laws. second, because of the co mple xity and specialty of the powe r industry’ reform, a mong developed countries, the reform must be improved by governments, and be supported by technology. serc should increasingly improve and consummate its regulatory functions. third, the reform should contain decomposition of business and management of centralization. brea king the monopoly and introducing competition are the core of re form o f power industry. so the authority should clearly define monopoly and competition, make t he part of co mpetition follow the laws of value, demand and supply, make the part of monopoly regulated by serc. fourth, the reform should be paid more attention to coordinate prices of coal and electricity, carry out the new mechanism of bidding, and strength market-oriented consumer guide. fifth, the government should make up national powe r technology innovation system and put power technological innovation as the important force for power industrial upgrading and the develop ment of new industries. . . exploit renewable energy-power as we a ll know that fossil energy source is the ma in reason of e mission of ca rbon dio xide. exp loitation of new energy is an efficient strategy [ ]. exploit hydropower hydroelectric power is one category of the power industry. ch ina has abundant water resources . however, the utilization rate of water resource is only about %, the degree of explo itation is far lower in ch ina than developed countries . the generation of hydropower is only less than conventional energy sources of coal. with the pressure of reducing e missions of carbon dio xide is increasing, the ro le of hydropower in the aspect of reducing carbon dioxide emissions is becoming more important. therefore, the government of ch ina should ma ke re lated polic ies to develop hydropower, to strengthen the protection of ecological environment and improve our existing system. fi gu re . u.s. el ectric power in dustry fi gu re . c omparison of greenhouse gas ne t s ummer c apacity, [ ] emi ssion i n whole en e rgy chain [ ] exploit wind power w ind power [ ] as one of clean and renewable energy, countries of the world is increasingly pay attention to develop it. the total storage of wind power is about . × mw in the pl anet. in , the . c oal; .fossil oil; .natural gas; . hydropower; . nuclear power; wind power; .solar thermal power; . biomass power carbon dioxide emissions g/(kwh) max min li yanbin et al. / energy procedia ( ) – generation of wind power , mw. therefore , the government should build a co mbining technical innovation system which involves business -oriented, industry, academia, and research . exploit solar thermal power abundant solar radiation is an important source of energy. solar energy is ine xhaustible, clean, cheap, and free to use human energy. in recent years, generation of solar therma l powe r has achieved a series of breakthroughs in technology. cost has significantly reduced. more than b locks large-scale solar therma l powe r plant in the world is running. many scientists predict that by the end of the century and the beginning of the ne xt century, solar power and conventional electric ity price may be reduced to the same level. exploit nuclear power nuclear powe r plant can produce large a mounts of electricity and only e xpend little nuclea r fue l. the cost per kwh is lo wer t % than thermal power p lant. nuclea r power station still can reduce traffic volume of fuel. fo r e xa mple , a coal-fired powe r plant of million kilowatts consumes - million tons of coal in every year. while the sa me nuclear powe r p lant only e xpend - tons uranium fuel each year. another advantage of nuclear power is clean, no pollution, is almost zero emissions. develop rural renewable energy power in china, rura l a reas have abundant hydropower, solar, wind, b io mass, etc. in this art icle, we take biomass power generation as an example to prove the potential of rural renewable energy power. the so-called bio mass power generation is that using cotton rod, straw stalks and other agricultural and forestry wastes as raw materia ls to generate electricity. the whole process of power generation link together to form a co mprehensive utilization of b io mass power generation, building green chains of straw, which will ring the origina l agricultura l production chain which can be recycled into a c losed -loop chain, is a completely turning waste into eco -economic model. . . comprehensive management of energy demand ‘de mand side manage ment’ [ ]re fers to using an effective incentive measures to guide users of electric powe r to change the way of consuming electric powe r, and imp rove the end-use efficiency, optimize resources, improve and protect the environ ment, to achieve the min imu m cost of e lectric ity services provided by the power management activities. management strategies of electric ity power demand: first, formu late and modify relevant la ws, regulations and polic ies to ensure administrative measures to be put into practice. in a global perspective, countries with better de mand side management, there are stringent laws and regulations. for e xa mp le, the government of usa has introduced the “national energy policy-act”, “public se rvice management po licy -act” and other laws and regulations, and developed a large number of mandatory energy efficiency standard to power companies and electricity consumers. second, reform and imp rove the system of e lectric price. adopt a fle xib le price that is di ffe rent price in different time and widen gap of seasonal prices, and improve the load rate of power grid. third, construct mu lti-incentive mechanis m. govern ment could adopt price an d economy means to enhance motivation of power companies and electricity customers for demand side manage ment. government could make a found for demand side management subsidies. . . cultivate high-quality power talents with the progress of technology and reform of manage ment mechanism, powe r enterprises are gradually transforming fro m the original manufacturer into integration in production, manage ment and service. when power industry is experiencing fast development, the structural contradictions of human li yanbin et al. / energy procedia ( ) – resource in power industry gradually appear. labour depart ment and e lectric ity power enterprises should cooperate to cultivate high-skill talents power engineering education [ ] is specialized to tra in high sophisticated professional of power system. with the development of power industry, more and more intelligent products will replace the original products. so the require ment to professional’ ma jor knowledge is increasingly high such as low - carbon technologies, the technologies of intelligent po wer grid and so on. it not only requires electrical engineers to grasp the power’ majo r knowledge, but also requires them proficient in mathemat ics and computer knowledge. the government should establish a special education fund and co mbine with appropriate incentives to support the training of power engineers. . conclusions th is paper is started with the national stage of china’s power industry and the international hot topic about coping electric energy crisis. then two typical cases about corresponding with strategies against power crisis are given. lastly, the paper is fro m the aspects of institutional reform in e lectricity ma rket , technological innovation and energy conservation , explo iting renewable energy-power, developing rural renewable energy power, co mprehensive management of energy demand and cultivating high-quality power talents to discuss how to cope with power crisis. acknowledgement the authors are very grateful to the anonymous referees for the insightful comments and suggestions. this research is supported by the natural science foundation of china under grant no. , the project supported by chinese universities scientific fund no. m r and hu manit ies and social sciences fund projects of ministry of education no. yja . references [ ] jorge f. dopazo, alberto m. sasson, p ersonal views on power engineering educat ion from an indust ry vantage p oint [j]. transctions on education, august , ( ); [ ] u.s. energy information administ ration, form eia- , “annual electric generator report; [ ] j.x. liu, “on t he st at us quo of t he wind p ower generat ion and t he incentives of it s development and ut ilizat ion,” taxation research, no. , august , . [ ] muhammad quamruzzaman, kazi mujibur rahman , development of control st rategy for load sharing in grid-connect ed p v p ower syst em [j], ieee- electrical and computer engineering , . [ ] u.a. korde, “lat ching cont rol of deep wat er wave energy devices using an active reference,” ocean engineering, vol. , pp. - , . [ ] h.l. zhou, “the development prospect s and strat egy of china’s wind power industry,” electrical technology, the t h issue, ; [ ] china’s electric st atist ical yearbook - [m]. beijing: china electric publishing house(ch); [ ] california independent syst em operator market design p roject comprehensive market design p roposal; apr. .[online).available :http://www.caiso.cnmldocsi / .pdf; [ ] cherni j a, kent ish j. renewable energy policy and electricity market reforms in china. energy policy , , : – ;. [ ] mettam gr, adams lb. how to prepare an elect ronic version of your art icle. in: jones bs, smit h rz, editors. introduction to the electronic age, new york: e-publishing inc; , p. – [ ] zhang bin primary energy and electricity consumpt ion forecast of china from perspect ive of hist orical trend of oecd count ries [j]. electric power technologic economics, , ( ); journal of neurotherapy: investigations in neuromodulation, neurofeedback and applied neuroscience introduction: blood flow hemoencephalography tim tinius phd a a department of psychology , st. cloud state university , whitney house, th avenue south, st. cloud, nm, - e-mail: published online: sep . please scroll down for article this open-access content made possible by these generous sponsors to cite this article: tim tinius phd ( ) introduction: blood flow hemoencephalography, journal of neurotherapy: investigations in neuromodulation, neurofeedback and applied neuroscience, : , - , doi: . / j v n _ to link to this article: http://dx.doi.org/ . /j v n _ © international society for neurofeedback and research (isnr), all rights reserved. this article (the “article”) may be accessed online from isnr at no charge. the article may be viewed online, stored in electronic or physical form, or archived for research, teaching, and private study purposes. the article may be archived in public libraries or university libraries at the direction of said public library or university library. any other reproduction of the article for redistribution, sale, resale, loan, sublicensing, systematic supply, or other distribution, including both physical and electronic reproduction for such purposes, is expressly forbidden. preparing or reproducing derivative works of this article is expressly forbidden. isnr makes no representation or warranty as to the accuracy or completeness of any content in the article. from to the journal of neurotherapy was the official publication of isnr (www. isnr.org); on april , isnr acquired the journal from taylor & francis group, llc. in , isnr established its official open-access journal neuroregulation (issn: - ; www.neuroregulation.org). http://dx.doi.org/ . /j v n _ http://www.neuroregulation.org/ http://www.appliedneuroscience.com/ http://brainmaster.com/ http://www.swingleclinic.com/ http://www.neurocaregroup.com/ introduction: blood flow hemoencephalography tim tinius, phd this special issue of the journal of neurotherapy entitled new devel- opments in blood flow hemoencephalography is a presentation of new literature on a technique developed directly from the field of neuro- therapy or neurofeedback. the technology to provide instant real time feedback of electrical changes in the brain has long been established. dr. toomim has spent the last several years creating and developing this technology called blood flow hemoencephalography or heg. neuro- feedback with this technique gives clinicians and researchers another method to measure, quantify and, most importantly, teach a person to change a measure of brain functioning via self-monitoring. i remember my first introduction to this technique at the society for the study of neuronal regulation (ssnr) conference in snowmass, colorado. im- mediately, i wondered “is this really a valid and reliable measure of brain functioning?” fast forward seven years to this special issue and my ques- tions are answered. this special issue brings you a variety of studies that explain the heg technology, describe the validity and reliability of the technology, describe many applications of heg and most importantly, show this technique can be applied to a wide variety of central nervous system symptoms that many clinicians in the international society for neuronal regulation (isnr) see on a daily basis. please note that this electronic prepublication galley may contain typographical errors and may be missing artwork, such as charts, photographs, etc. pagination in this version will differ from the published version. tim tinius is affiliated with the department of psychology, st. cloud state univer- sity, whitney house, th avenue south, st. cloud, nm - (e-mail: tinius@cloudnet.com). [co-indexing entry note]: “introduction: blood flow hemoencephalography.” tinius, tim. co- published simultaneously in journal of neurotherapy vol. , no. , , pp. - ; and: new developments in blood flow hemoenceph-alography (ed: tim tinius) , pp. - . copyright © isnr. all rights reserved. digital object identifier: . /j v n _ a commonality that i see among the persons receiving treatment de- scribed in these special issue articles is a problem of underlying arousal. a change in arousal and function can be seen in athletes who have sus- tained a concussion during a sport. a recent review of the literature on concussion or mild traumatic brain injury in sports suggested that after a concussion axonal fibers are stretched and become swollen, beaded or varicose (echemendia & julian, ). the neurochemical and meta- bolic changes after a concussion begin within the first hour of insult and continue for up to days post injury as the neurons are alive, but exist in a vulnerable state (hovda et al., ). this vulnerability is charac- terized by an increase in the demand for glucose (fuel) and a reduction in cerebral blood flow (fuel delivery) and as a result, the neurovascular system is rendered unable to respond to demands for the energy required to return to normal neurochemical and ionic environments (hovda et al., ). the duration of decreased cerebral blood flow may be a cardinal factor in predicting outcome of persons with mtbi (hovda et al., ). there is a strong relationship between the concentration of ca + and re- gional control of cerebral blood flow as those regions of the brain exhib- iting ca + flux show reduced cerebral blood flow after traumatic brain injury (wojtys et al., ). although the exact mechanism of ca + flux after a concussion remains in question, it is quite clear that cerebral con- cussion may not, in and of itself, produce extensive neuroanatomic damage, but the surviving cells are placed in a state of vulnerability best characterized in terms of a metabolic dysfunction (wojtys et al., ). the cascade of events leading to this dysfunction is multidimensional, resulting initially in acute periods of hyperglycolysis, followed by a chronic period of metabolic depression (wojtys et al., ). in general terms, this dysfunction may be thought of as a breakdown in the har- mony between energy demand, production, and delivery of oxygen (wojtys et al., ). this energy crisis after traumatic brain injury was documented years ago (jaggi, obrist, & gennarelli, ). in recent studies, changes in cerebral blood flow (cbf) measured on days one through five post-injury correlate positively with long-term neurologi- cal outcome (kelly et al., ). further, older age and more severe in- jury (as defined by pupillary abnormalities and incidence of evacuated subdural and intracerebral hematomas) are the most important clinical factors associated with low cbf during this period. these findings sug- gested the longer the duration of reduced flow (determined by the num- ber of observations in which cbf was less than ml/ g/minute) the worse the outcome (kelly et al., ). the importance of these find- ings is clear as clinical guidelines for concussion management describe new developments in blood flow hemoencephalography changes in blood flow to account for the symptoms after concussion (wojtys et al., ). when i read the physiology and cellular changes from the concussion and sports research, i immediately notice that the guidelines do not talk about active treatment. the current treatment of concussion is passive treatment of medication monitoring, no treatment, removal of activity, or education (wojtys et al., ). after i read the articles in this special issue, i concluded that heg neurofeedback may have promise as an ac- tive treatment in the alleviation of symptoms in athletes with a con- cussion. research suggests that athletes with a concussion experience a blood flow crisis, but now there is technology that could assist in the resolution of this crisis and alleviate symptoms very soon after a con- cussion. future research with the use of blood flow heg neurofeedback in the clinical population of the concussed athlete can be a key to the de- velopment of heg neurofeedback or neurotherapy. as you read this special issue on blood flow hemoencephalography (heg), i would strongly suggest that you develop research ideas, collect research data, and publish the results of clinical populations where this technology was used and shown to be effective. references echemendia, r. j., & julian, l. j. ( ). mild traumatic brain injury in sports: neuropsychology’s contribution to a developing field. neuropsychology review, ( ), - . hovda, d. a., yoshino, a., kawamata, t., katayama, y., fineman, i., & becker, o. p. ( ). the increase in local cerebral glucose utilization following fluid percussion brain injury is prevented with kynurenic acid and is associated with an increase in calcium. acta neurochir, , (supplement), - . jaggi, j., l., obrist, w. d., & gennarelli t. a. ( ). relationship of early cerebral blood flow and metabolism to outcome in acute head injury. journal of neurosur- gery, , - . kelly, d. f., martin, n. a., rouzbeh kordestani, d., counelis, g., hovda, d., berg- sneider, m., et al. ( ). cerebral blood flow as a predictor of outcome following traumatic brain injury. journal of neurosurgery, ( ), - . wojtys, e. m., hovda, d., landry, g., boland, a., lovell, m., mccrea, m., et al. ( ). concussion in sports. the american journal of sports medicine, ( ), - . introduction 	j v n _ 	v i _j v n _ department of community health, university of auckland, private bag, auckland, new zealand ian roberts, acc training fellow in epidemiology, injury prevention research centre roger marshall, senior lecturer in biostatistics robyn norton, acc senior fellow and director, injury prevention research centre correspondence and requests for reprints to: dr roberts. bmj ; : relation between child pedestrian death rates (a), traffic volume (-), and rates predicted by model (o) department of cardiology, beaumont hospital, po box , dublin , republic of ireland hannah m mcgee, health psychologist john h horgan, consultant cardiologist correspondence to: dr mcgee. bmj ; : child pedestrian mortality and traffic volume in new zealand ian roberts, roger marshall, robyn norton pedestrian injuries are a leading cause of childhood mortality.' the analysis of trends in pedestrian death rates may provide information on the determinants of the incidence of these injuries. we have examined the relation between child pedestrian mortality and traffic volume in new zealand from to . methods and results child (aged < years) pedestrian death rates (icd code e - ) were calculated by using national health statistics centre mortality data for to . a traffic volume index, based on data from traffic coun- ters on urban highways throughout new zealand, and the number of registered vehicles were obtained from the ministry of transport. there was an annual average of pedestrian deaths over the study period ( - / children yearly). from to there was a - % increase in traffic volume and a - % increase in the death rate. between and traffic volume increased by only - % and death rates fell by - %. after traffic volume rose by - % and death rates by - % (see figure). the number or registered vehicles increased steadily by - % between and . . x . n ) . l l l l l l l . year the trend in child pedestrian death rates was examined by poisson regression modelling. death rate was the dependent variable and traffic volume index (v), number ofregistered vehicles (r), and year (y) the explanatory variables. the expected death rate (f) was modelled by a log linear equation, of the form: log f=po+ivv+ iyy+ prr. after fitting the model only the variables v (bi,= , se - ; p= ) and y (by=- - , se ; p= ) were signifi- cant. the number of registered vehicles (r) was not significant in the model (p= ) or in a model with only r and y (p= ). when rates were modelled with the unusual year excluded the coefficients were essentially unchanged. the relation between the death rates, traffic volume, and rates predicted by the model are shown in the figure. comment a definite decline in child pedestrian death rates occurred between and , a period in which there was very little growth in traffic volume. the energy crisis of , which was accompanied by a fourfold increase in the price of petrol, was probably important in retarding the growth in traffic volume. as a result of the crisis the new zealand government introduced "carless days" (when each car was required to be off the road for one day each week) and a ban on weekend petrol sales, which lasted until august . that the pedestrian death rates fell, as opposed to having levelled off in line with the plateau in traffic volume, suggests that the safety of the transport system was also improving during the period. the results of modelling support these findings. a positive coefficient was derived for traffic volume, showing that death rates increase when traffic volume increases. a negative coefficient was derived for year, showing that, after controlling for traffic volume, death rates decline over time. the impressive fall in death rates that occurred between and suggests that limiting the future growth in traffic volume has the potential significantly to reduce child pedestrian mortality. this would require public policy changes that strengthen the public transport system, discourage the use of private vehicles, promote cycling, and encourage the use of rail, river, and sea transport by freight. ulti- mately the impetus for reducing the growth in traffic volume may come from an increasing awareness of the health effects of road traffic apart from injury. with cities in britain, north america, and australia having recently experienced episodes of photochemical pollu- tion, the environmental effects of motorisation are increasingly becoming the focus of attention. we thank professor robert beaglehole for critical comments on the manuscript. national health statistics centre. mortality and demographic data . wellington: department of health, . rose g. sick individuals and sick populations. intj epidemiol ; : - . frome el. the analysis of rates using poisson regression models. biometrics ; : - . department of statistics. new zealand official yearbook . wellington: department of statistics, . read rc, green m. internal combustion and health. bmj ; : - . (accepted may ) cardiac rehabilitation programmes: are women less likely to attend? hannah m mcgee, john h horgan cardiac rehabilitation programmes offer valuable secondary prevention after myocardial infarction and other cardiac events. research attests to the effective- ness of rehabilitation programmes-for example, in decreasing death rates after myocardial infarction.' however, the evidence is based almost exclusively on male patients under . though the positive impact of exercise training by female cardiac patients has been documented, women are perceived as being less motivated to attend structured programmes, especially those entailing vigorous exercise. some studies have noted higher drop out rates for women. oldridge and colleagues noted a higher one year drop out rate from a cardiac rehabilitation pro- gramme for female ( / ; %) than male ( / ; %) patients after myocardial infarction or coronary artery surgery in the s. a study of similar patients in the early s found a female drop out rate of % (v - % in men) and a lower programme attendance record for women ( % v %) (n= women, men). bmj volume august o n a p ril b y g u e st. p ro te cte d b y co p yrig h t. h ttp ://w w w .b m j.co m / b m j: first p u b lish e d a s . /b m j. . . o n a u g u st . d o w n lo a d e d fro m http://www.bmj.com/ sustainability article not there yet: mapping inhibitions to solar energy utilisation by households in african informal urban neighbourhoods aliyu salisu barau ,*, aliyu haidar abubakar and abdul-hakim ibrahim kiyawa department of urban and regional planning, bayero university kano, kano , nigeria department of environmental management, bayero university kano, kano , nigeria; ahabubakar.em@buk.edu.ng tianjin key laboratory of indoor air environmental quality, tianjin university, tianjin , china; aikiyawa@tju.edu.cn * correspondence: asbarau.urp@buk.edu.ng received: october ; accepted: december ; published: january ���������� ������� abstract: the average household access to electricity in nigeria is estimated at four hours per day. this paradoxical energy crisis in a top oil and gas exporting country makes an interesting case for local and global players in the sustainable energy agenda. the current study showcases experiences of households that installed and use solar photovoltaic (pv) technologies in urban africa. it identifies the key sociotechnical transition issues that shape the households’ solar energy adoption strategies. to get a clear picture of the situation, the study focuses on the kano urban agglomeration—a densely populated city with high economic activities. to answer the research question, the sampled respondents shared their experiences via questionnaire and interviews. similarly, field observations guided the research team to identify patterns of household solar energy use, and how urban planning, building, and roofing types inhibit solar energy utilisation. from the results of the study, it appeared that households use solar energy for lighting, energising rechargeable appliances, and cooling of houses. nevertheless, none of the respondents use solar photovoltaics (pvs) for cooking—the biggest consumer of fuelwood in nigeria. finally, this study is optimistic that despite the challenges identified, the transition to clean energy security in africa is achievable through coordinated efforts of people, industry, and governments. the transition to renewables by households promises significant changes that can lever the mainstreaming of the un sustainable development goals-sdg no. . keywords: energy; sdgs; urban planning; sustainability; transition; socio-technical . introduction affordable and clean energy is one of the sustainable development goals (sdgs-goal no. ) designed to tackle the challenges of dirty energy and low access to energy by communities around the world. indeed, one of the strategies to combat climate change and other development challenges is investment in renewable energy. this strategy can improve poor households’ access to energy in developing countries. since the launch of the sdgs in , some progress has been made in their implementation. a forecast by the iea (international energy agency) [ ] has suggested that the global renewable energy output will expand by % between and with solar photovoltaic (pv) taking the lead. it is evident from some studies that sub-saharan africa has in recent years made some progress in off-grid connections particularly in the solar energy sector [ ]. although, there is an irony associated with africa’s renewable energy development, on the one hand, the quest for economic development supports it, and on the other population growth impedes it [ ]. some critical scholars have decried the rate at which large scale renewable energy projects fail in sub-saharan africa [ ]. it is sustainability , , ; doi: . /su www.mdpi.com/journal/sustainability http://www.mdpi.com/journal/sustainability http://www.mdpi.com http://dx.doi.org/ . /su http://www.mdpi.com/journal/sustainability https://www.mdpi.com/ - / / / ?type=check_update&version= sustainability , , of important to add that one can only create a big picture of energy crises in africa by reflecting on the level of inequality in energy access within the region [ ]. considering the challenges outlined above, many studies have stressed the importance of transitions to clean energy in africa. studies have also shown the extent of energy poverty among african households. for instance, only about % of households of africa’s most populous country—nigeria—have access to electricity [ ]. while this situation remains, the potentials of renewables and especially for businesses is shown to be high in richer nigerian urban areas [ ]. therefore, it becomes important to explore the experiences of households with respect to access to renewable energy and to understand challenges and opportunities for improving access and sustainable development of the renewables sector. indeed, there are plenty of studies that focus on households and renewables from across the globe. for instance, studies from technologically advanced countries have focused on households and renewables in contexts of financing and payment mechanisms for systems that work or are efficient [ – ]. nevertheless, in developed countries the renewables range from mixed, hydrogen, solar photovoltaic and others. thus, issues investigated by researchers in those countries range from participation, governance, investment, consumption patterns and user perceptions. on the other hand, in spite of the potentials of cleaner energy sources such as solar energy across africa, the number of households using solar energy remains insignificant [ ]. however, the fact that urbanization is growing ever faster in africa suggests that renewable energy and in particular solar photovoltaic (pv) technologies are an indispensable option for the urban poor and middle-income population. whilst there are other options and potentials for renewables, many of them are at rudimentary stages of research and development. for example, heat energy transfers within urban informal settlements could have a high potential of energy generation and emission reduction [ ]. currently, this technology requires investments and perhaps long-term planning and financing mechanisms. the most cost-effective risk mitigation strategy is to gradually replace large-scale electricity exports with domestic solar energy which is abundant in africa. solar energy is no doubt one of the easiest short cuts for attaining universal access to clean energy in africa. for african countries, solar energy is the cheapest and it enhances national energy sovereignty, is climate friendly, and it erodes regional generation and transmission dependencies [ ]. given this, it is apparent that households will potentially be one of the major beneficiaries of solar technology development. it has been revealed that in africa, many factors determine the adoption of solar technology by households; and these factors range from household headship by gender, levels of education and income [ ]. such neighbourhood-based findings have left some issues relating to urban planning situations, households’ behavioural disposition in relation to use of solar energy and also a number of technological challenges such as repairs for gadgets. such are important gaps that need to be filled in order to understand the challenges of transitions to solar energy adaption in african countries. more so, it is important to note that most low and middle-income households in african countries live in informal settlements characterised by poor urban planning. in effect, it is estimated that – % of african urban population live in slums and informal neighbourhoods [ ]. theoretically speaking, household transitions to clean energy are in three main domains: adoption of solar photovoltaics (pvs), the residential heating system (rhs), and alternative fuel vehicles (afvs) [ ]. considering the level of economic and technological underdevelopment in africa, more attention is needed on solar pvs and how households interact with this technology. recently, some scholars have critiqued the theoretical basis of african urban households’ clean energy transitions. in the opinion of [ ] and [ ], it is imperative for academic and policymakers to consider engagement of end users in co-production of solutions to the energy crisis. often, socio-technical transition scholars underscore the complexities of clean energy transitions in relation to interactions of science, engineering, policy, people and how these reshape the future [ ]. however, such notions are more correct in the context of developed economies where planned transitions may follow normative and linear pathways. in the case of sub-saharan africa, households sustainability , , of may be open to too little choices among others due to urban planning and constraints of informality. across urban areas around the world, transition to clean energy is undermined by behavioural, technological, and institutional lock-ins [ ]. therefore, this is hardly not true for sub-saharan african countries. the main research question driving this study is the following: what is the nature of solar energy adoption and utilisation in african cities? the current study showcases households’ experiences of utilising and living with solar energy from solar photovoltaic (pv) technology. the study also identified the key sociotechnical transition issues that shape households’ solar energy adoption patterns. to get a clear picture of the situation, the study focuses on the kano urban agglomeration—a densely populated city with preponderance of economic activities. however, this major urban area has a dominance of informal economy and informal settlements adjoining it. therefore, it justifies its selection as a focus for understanding solar pv in informal neighbourhoods—a settlement type—that represents the situation of over of africa’s urban areas as demonstrated by [ ]. this article is subdivided into four sections with an introduction setting the scene of the research and its main goal. the introductory part of the paper also sheds light on nigeria’s energy crises and the need for faster transition to clean energy as one of the vehicles for socio-economic transformation and implementation of the sdgs. the methods section outlines the study design processes and details of the study area appear in the second section. the findings are given in third section where the results and their implications are discussed. key recommendations and the overall meaning of the study and its connections to the global sustainable energy agenda are given in the concluding section. an overview of nigeria’s energy crisis and potentials for transition to renewables the body of literature has explained much on the state of the energy crisis in sub-saharan africa. although, the current study largely explores the situation of urban households, it is important to understand that the success or failure of renewable energy largely depends on the resource base and the policy climate of a given country. for instance, based on its geographical location, nigeria receives an average daily solar intensity of . mj/m /day; the wind speed ranges from . to . ms− ; with vast potentials of biomass, geothermal and water [ ]. the authors maintain that the current . mw produced in nigeria is seriously inadequate for its projected population of million by . currently, hydropower has the best renewable energy potential, which amounts to , mw for large hydropower and mw for small hydropower [ ]. since of all the renewables, solar energy technology is seemingly the most accessible by poorer households, it is critical to understand its distributional situation in nigeria. ozoegwu et al. [ ] revealed that previously and even currently nigeria has lacked experience of grid-connected solar power integration although the future may be promising. apparently, this implies that the potentials lie more with households and businesses to own and maintain solar pv technologies. regardless of their situation now, energy policies and the decision-making process will play an important role in determining the success or failure of the adoption process of solar pvs and other renewables by households in nigeria. it could be said that some of the barriers to attaining sustainable energy in nigeria cannot be separated from governance and policy issues. for instance, [ ] identified cost and pricing barriers; market performance barriers, and legal and regulatory barriers as impediments of sustainable energy development in nigeria. as such, building on the above premise, it is strongly recommended that the policy-making processes should fast track provision of energy infrastructure through: granting access to data; regulations; and issuance of licenses [ ]. the authors cautioned that by failing to do so, the nigerian government will end up financing corruption in the energy sector; injecting economic delusion; and having uncontrolled growth in export-based energy demand [ ]. energy imbalance and inequality between cities and industrial areas on one hand, and rural areas and places of the poor is alarmingly disproportionate. the nature of energy disenfranchising in nigeria is high to the extent that % to % of the population lacks access to electricity [ ]. this apparent sustainability , , of energy insecurity has implications on environmental sustainability, where for instance, over % of the population rely on fuelwood, charcoal and other biomass energy sources for cooking [ ]. despite this, fuelwood is yet to be prioritised and wholly recognised in the context of current renewable energy transition discourses in respect of nigerian urban centres [ ]. another aspect to the challenge is that low and middle-income households that cannot cope with raising prices of kerosene and cooking gas shift to firewood [ ]. this situation will particularly increase pressure on woody plant species within and around urban agglomerations. . materials and methods . . study area urban kano is located on the central plains of northern nigeria also called kao plains. the area bestrides latitude , ′ . – , ′ . n and longitudes ′ . – ′ . e. it lies in the northern part of nigeria and is located some km away from the edge of the sahara desert and km from the atlantic ocean [ ]. urban kano constitutes the old city, fagge and the metropolitan areas which together serve as the capital city of kano state. the kano urban area covers sq km and comprises eight local government areas (lgas)—kano municipal, fagge, dala, gwale, tarauni, nassarawa, kumbotso and ungogo [ ]. the population of the study is estimated to be approximately . million making it the second largest metropolitan area in nigeria [ ]. solarimeter readings of solar radiation in urban kano using a modified fluke datalogger revealed that within a period of one year, the city receives w m− [ ]. however, a recent computer-driven study determined the optimum slope angle for solar radiation collectors in kano [ ]. the findings suggested that for maximum solar collection, the optimum angle of each month should be set to the seasonal tilt angles—horizontal from april to september—and then set to kano’s latitude plus ◦ for the other months. thus, the sloping of the solar collector to the monthly optimum tilt angle brings radiation gain throughout the year and up to . % and . % in december and january. given this, it is critical to investigate the current state of solar adoption in an area that is characterised by high consumption of fuelwood and where its energy transitions have also attracted the attention of many researchers [ , , ]. . . sampling of solar pv users recent studies have argued that households give a clearer picture of true energy access and dynamics of transition to renewables [ , ]. the population of kano metropolis (and its agglomeration) is projected to be between to million people [ ]. the challenge of access to energy for this population is clear. according to the nigerian data portal ( ), only . percent ( , people) of residents of kano metropolis use solar energy technology. thus, following [ ], the sample size for the pv users (target population) was calculated using the raosoft online sample size calculator, this is an online sampling size calculator that suggests an ideal sample size for a given population (http://www.raosoft.com/samplesize.html). with such insignificant number of solar energy users in the study area and more with an unspecified population, focussing on urban households helped the study to answer its research question. studies rely on this model to determine the minimum sample size for social and health related research [ ]. the population of solar users ( , ) was inputted and the software suggested a sample of respondents in kano metropolis and a five percent margin error of ( ) was added making a total of which was rounded up to . . . sampling of the study sites for the purpose of sampling the study locations, two diagonal lines crossing each other were drawn on the map of kano metropolis, thereby dividing the map into four parts. consequently, five ( ) points representing major neighbourhoods were chosen at random from each of the four segments, thereby making a total of twenty ( ) neighbourhoods. afterwards, ten ( ) respondents (solar pv adopters) were selected from each locality, thus giving a total of respondents. this number was http://www.raosoft.com/samplesize.html sustainability , , of appropriate for this kind of study because a recent review paper suggested that the average sample size for lighting (energy) publications is [ ]. for most studies on energy, the selected respondents answered questions on behalf of the sampled participating households/houses identified. the study was supported by two field assistants with many years of fieldwork experiences in kano city and perhaps this helped in achieving % response within the two years of the study ( – ). some % of the respondents were male household heads, an additional % of the respondents were educated adult male members of the selected households, while only % of the solar energy using households were headed by females. for the questions asked please see the supplementary list. the selected sites include: hotoron arewa, kundila, yar akwa, kuntau, tudun yola, gadon kaya, fagge, rimin gata, kofar wambai, yola, unguwar gini, sharada, alfindiki, sheka, bakin zuwo, chedi, bompai, durumin iya, dakata and gandun albasa. see figure for location of the study sites. sustainability , , x for peer review of average sample size for lighting (energy) publications is [ ]. for most studies on energy, the selected respondents answered questions on behalf of the sampled participating households/houses identified. the study was supported by two field assistants with many years of fieldwork experiences in kano city and perhaps this helped in achieving % response within the two years of the study ( – ). some % of the respondents were male household heads, an additional % of the respondents were educated adult male members of the selected households, while only % of the solar energy using households were headed by females. for the questions asked please see the supplementary list. the selected sites include: hotoron arewa, kundila, yar akwa, kuntau, tudun yola, gadon kaya, fagge, rimin gata, kofar wambai, yola, unguwar gini, sharada, alfindiki, sheka, bakin zuwo, chedi, bompai, durumin iya, dakata and gandun albasa. see figure for location of the study sites. figure . locations of the study sites in urban kano. . . procedure for data collection and analysis a semi-structured questionnaire was designed comprising both open-ended and closed-ended questions so as to avoid bias, ambiguity, or uncertainty in the answers provided. the questionnaire was divided into sections that sought demographic, socio-economic and technical information from the respondents. options were given for closed-ended questions, while the likert scale was used for questions with options ranging from – signifying various levels of agreement or disagreement with figure . locations of the study sites in urban kano. . . procedure for data collection and analysis a semi-structured questionnaire was designed comprising both open-ended and closed-ended questions so as to avoid bias, ambiguity, or uncertainty in the answers provided. the questionnaire was divided into sections that sought demographic, socio-economic and technical information from sustainability , , of the respondents. options were given for closed-ended questions, while the likert scale was used for questions with options ranging from – signifying various levels of agreement or disagreement with the pre-determined answers. the questions also elicited responses on problems encountered and level of adoption by households. similarly, a fieldwork was carried out between and to ascertain some sociotechnical related issues that could be impediments to adoption of solar pvs by households. the issues covered include the appropriateness of siting pvs in houses located in the study area. descriptive statistics were used to compute means, standard deviation percentages and frequencies of data such as problems of adoption and level of adoption. all data were presented in tables and charts containing frequencies, mean, and standard deviation while percentages were calculated in microsoft excel and spss software version . . where necessary, quotations of respondents were presented to stress important points or patterns. the summary of the research design is diagrammatically given in figure : sustainability , , x for peer review of the pre-determined answers. the questions also elicited responses on problems encountered and level of adoption by households. similarly, a fieldwork was carried out between and to ascertain some sociotechnical related issues that could be impediments to adoption of solar pvs by households. the issues covered include the appropriateness of siting pvs in houses located in the study area. descriptive statistics were used to compute means, standard deviation percentages and frequencies of data such as problems of adoption and level of adoption. all data were presented in tables and charts containing frequencies, mean, and standard deviation while percentages were calculated in microsoft excel and spss software version . . where necessary, quotations of respondents were presented to stress important points or patterns. the summary of the research design is diagrammatically given in figure : figure . research design process followed in the study. . results and discussion . . analysis of how households use their solar pvs the analysis of the study variables is presented in table which shows that households use their pvs mainly for lighting. less than half of the respondents use solar energy for charging of appliances such as phones, rechargeable lamps and other rechargeable appliances. however, utilisation of solar urban households solar energy adoption issues: energy insecurity, socio- technical transitions, urban informality, clean energy identfication of households, sampling of study partcipants, formulation of research quetion literature review questionnaire admiistration and observation of solar pvs siting results, analysis and interpretation picture of the current state of solar pv adoption in urban kano current state of solar adoption in the context of local and global clean energy dynamics figure . research design process followed in the study. sustainability , , of . results and discussion . . analysis of how households use their solar pvs the analysis of the study variables is presented in table which shows that households use their pvs mainly for lighting. less than half of the respondents use solar energy for charging of appliances such as phones, rechargeable lamps and other rechargeable appliances. however, utilisation of solar for water pumping (powering boreholes) has the lowest percentage as less than one-tenth of the households used it for pumping of water. therefore, in this case, it is clear that only a few households have a high number of panels that can generate sufficient energy for water pumping. table . a descriptive analysis of how households use solar energy. variables sum mean std. deviation usage of solar pvs lighting . . charging appliances . . cooling and heating . . pumping . . television and radio . . night versus daytime usage morning usage . . afternoon usage . . night usage . . hours of solar usage – h – h – h – h based on the responses drawn from this study, solar energy is mostly used for house lighting. this is likely to occur because most households light up their houses even if they have no other electric appliances. this is in line with findings by [ ] where it was revealed that lighting and ventilation had the highest annual consumption of electricity in nigerian states. on the other hand, the daily average duration of solar energy consumption was found to be highest among households that used it between to h, accounting for almost one-third of the solar users. the general pattern of duration of usage may be insufficient but is still better than the average national grid supply of four hours experienced in nigeria [ ]. the variation between night and daytime usage of solar energy shows that the majority ( %) of the households use solar energy during the nightfall. this is because there is need to illuminate the houses, coupled with the fact that most people are at home and need to watch television and cool their surrounding using fans and low energy air conditioners. on the other hand, only one-third of the solar users makes use of it in the morning, while one-quarter uses it in the afternoon. this study found that about % of the solar energy adopters in the study area installed their system between and while the remainder had acquired them before. this reveals an increase in the adoption of renewables by the kano urban households in recent years (see figure ). figure shows the challenges encountered by households that have embraced solar pv technology. the major challenge identified by the respondents is associated with the reduced duration of charge retention by the batteries. about percent of the respondents pointed at this problem while others complained of poor charging, inverter malfunction and solar panel problem. technical and maintenance problems have been identified by [ – ] as the major problems of solar adoption. in the interview conducted, some of the households noted that inadequacy of technically skilled manpower, coupled with low quality products in the market make the lifespan of the system shorter. in this regard, it has sustainability , , of been observed that component failure occurs when a fully installed operational device such as home device becomes un-operational shortly after installation [ ]. since the adoption of solar energy is relatively new in africa, users are discouraged when the performance is below their expectations.sustainability , , x for peer review of figure . years since installation of solar pvs as at the time of the study in / . figure shows the challenges encountered by households that have embraced solar pv technology. the major challenge identified by the respondents is associated with the reduced duration of charge retention by the batteries. about percent of the respondents pointed at this problem while others complained of poor charging, inverter malfunction and solar panel problem. technical and maintenance problems have been identified by [ – ] as the major problems of solar adoption. in the interview conducted, some of the households noted that inadequacy of technically skilled manpower, coupled with low quality products in the market make the lifespan of the system shorter. in this regard, it has been observed that component failure occurs when a fully installed operational device such as home device becomes un-operational shortly after installation [ ]. since the adoption of solar energy is relatively new in africa, users are discouraged when the performance is below their expectations. figure . technical challenges encountered by solar photovoltaic (pv) adopters. the result also revealed that about % of households reported they replaced their batteries at least once. this is so because batteries have lifespans and need to be replaced after some time. however, as at the time of this study only % of the respondents were yet to replace their batteries. battery problems are mostly encountered due to some factors such as poor maintenance as a result of inadequate technical know-how or sales of substandard products [ ]. out of those who changed batteries, which represents about three in every five, about one quarter replaced batteries at least once since installation, while one fifth changed batteries at least once a year, and over one-tenth replaced % % % % % year years years years years and above % % % % % poor charging reduced duration inverter malfunction solar panel problem none figure . years since installation of solar pvs as at the time of the study in / . sustainability , , x for peer review of figure . years since installation of solar pvs as at the time of the study in / . figure shows the challenges encountered by households that have embraced solar pv technology. the major challenge identified by the respondents is associated with the reduced duration of charge retention by the batteries. about percent of the respondents pointed at this problem while others complained of poor charging, inverter malfunction and solar panel problem. technical and maintenance problems have been identified by [ – ] as the major problems of solar adoption. in the interview conducted, some of the households noted that inadequacy of technically skilled manpower, coupled with low quality products in the market make the lifespan of the system shorter. in this regard, it has been observed that component failure occurs when a fully installed operational device such as home device becomes un-operational shortly after installation [ ]. since the adoption of solar energy is relatively new in africa, users are discouraged when the performance is below their expectations. figure . technical challenges encountered by solar photovoltaic (pv) adopters. the result also revealed that about % of households reported they replaced their batteries at least once. this is so because batteries have lifespans and need to be replaced after some time. however, as at the time of this study only % of the respondents were yet to replace their batteries. battery problems are mostly encountered due to some factors such as poor maintenance as a result of inadequate technical know-how or sales of substandard products [ ]. out of those who changed batteries, which represents about three in every five, about one quarter replaced batteries at least once since installation, while one fifth changed batteries at least once a year, and over one-tenth replaced % % % % % year years years years years and above % % % % % poor charging reduced duration inverter malfunction solar panel problem none figure . technical challenges encountered by solar photovoltaic (pv) adopters. the result also revealed that about % of households reported they replaced their batteries at least once. this is so because batteries have lifespans and need to be replaced after some time. however, as at the time of this study only % of the respondents were yet to replace their batteries. battery problems are mostly encountered due to some factors such as poor maintenance as a result of inadequate technical know-how or sales of substandard products [ ]. out of those who changed batteries, which represents about three in every five, about one quarter replaced batteries at least once since installation, while one fifth changed batteries at least once a year, and over one-tenth replaced batteries at least once in two years. it is known that batteries have a lifespan, and all solar pvs require batteries to store the energy. it is for that reason that battery lifespan is very important to adopters, the longer the lifespan the better. sustainability , , of . . challenges to effective transition to solar pv energy besides the use-related challenges identified by households, there are several other challenges that may arise from the nature of placement of the solar pv panels on buildings, the location within urban planning typology and the type of building or roofing style. it is crucial to pay attention to these factors in order to understand renewable energy transition dynamics of african households. other issues relate to discipline and the decision-making process in the use of electrical appliances plugged into the household solar energy system. out of the houses within the neighbourhoods observed ( . %) of them are located in unplanned parts of the city. this suggest the predominance of solar energy adoption in informal settlements as is common with a typical african urban area [ ]. this may at the same time imply that formally planned areas receive more electricity supply. on the other hand, . % of the buildings are duplex compared to . % duplex type and % that are a mix of the two. an interpretation of this situation could be that individuals that own duplex houses or occupy them by renting have higher economic status. in relation to type of building and planning area, the study found that the neighbouring houses’ type of building significantly affects the quality of solar energy that households can enjoy. this has to do with for instance a situation whereby a neighbouring duplex house can block sunrays for a neighbouring bungalow building that has installed solar pv panels. similarly, types of roofing vary in both planned and unplanned neighbourhoods of urban kano. as such, the study found that % of the households have hip type of roofing whereas % have gable roofs while % have gable roofing style. the type of roofing affects the adoption of solar energy in two ways: first it affects the solar radiation to the next building; and second, it affects the solar radiation for the panels mounted on the roof. the angle of inclination of the roof affects the solar radiation if the angle of movement of the sun is not in consonance with the roof tilt angle. this has an effect on the energy output because according to [ ], at any location on the earth, solar output is affected by its tilt and azimuth angles. these angles play an important role in the efficiency of the solar photovoltaic panel (see figure ; figure ). sustainability , , x for peer review of batteries at least once in two years. it is known that batteries have a lifespan, and all solar pvs require batteries to store the energy. it is for that reason that battery lifespan is very important to adopters, the longer the lifespan the better. . . challenges to effective transition to solar pv energy besides the use-related challenges identified by households, there are several other challenges that may arise from the nature of placement of the solar pv panels on buildings, the location within urban planning typology and the type of building or roofing style. it is crucial to pay attention to these factors in order to understand renewable energy transition dynamics of african households. other issues relate to discipline and the decision-making process in the use of electrical appliances plugged into the household solar energy system. out of the houses within the neighbourhoods observed ( . %) of them are located in unplanned parts of the city. this suggest the predominance of solar energy adoption in informal settlements as is common with a typical african urban area [ ]. this may at the same time imply that formally planned areas receive more electricity supply. on the other hand, . % of the buildings are duplex compared to . % duplex type and % that are a mix of the two. an interpretation of this situation could be that individuals that own duplex houses or occupy them by renting have higher economic status. in relation to type of building and planning area, the study found that the neighbouring houses’ type of building significantly affects the quality of solar energy that households can enjoy. this has to do with for instance a situation whereby a neighbouring duplex house can block sunrays for a neighbouring bungalow building that has installed solar pv panels. similarly, types of roofing vary in both planned and unplanned neighbourhoods of urban kano. as such, the study found that % of the households have hip type of roofing whereas % have gable roofs while % have gable roofing style. the type of roofing affects the adoption of solar energy in two ways: first it affects the solar radiation to the next building; and second, it affects the solar radiation for the panels mounted on the roof. the angle of inclination of the roof affects the solar radiation if the angle of movement of the sun is not in consonance with the roof tilt angle. this has an effect on the energy output because according to [ ], at any location on the earth, solar output is affected by its tilt and azimuth angles. these angles play an important role in the efficiency of the solar photovoltaic panel (see figure ; figure ). figure . solar pv panels mounted over a hip roof. figure . solar pv panels mounted over a hip roof. sustainability , , x for peer review of batteries at least once in two years. it is known that batteries have a lifespan, and all solar pvs require batteries to store the energy. it is for that reason that battery lifespan is very important to adopters, the longer the lifespan the better. . . challenges to effective transition to solar pv energy besides the use-related challenges identified by households, there are several other challenges that may arise from the nature of placement of the solar pv panels on buildings, the location within urban planning typology and the type of building or roofing style. it is crucial to pay attention to these factors in order to understand renewable energy transition dynamics of african households. other issues relate to discipline and the decision-making process in the use of electrical appliances plugged into the household solar energy system. out of the houses within the neighbourhoods observed ( . %) of them are located in unplanned parts of the city. this suggest the predominance of solar energy adoption in informal settlements as is common with a typical african urban area [ ]. this may at the same time imply that formally planned areas receive more electricity supply. on the other hand, . % of the buildings are duplex compared to . % duplex type and % that are a mix of the two. an interpretation of this situation could be that individuals that own duplex houses or occupy them by renting have higher economic status. in relation to type of building and planning area, the study found that the neighbouring houses’ type of building significantly affects the quality of solar energy that households can enjoy. this has to do with for instance a situation whereby a neighbouring duplex house can block sunrays for a neighbouring bungalow building that has installed solar pv panels. similarly, types of roofing vary in both planned and unplanned neighbourhoods of urban kano. as such, the study found that % of the households have hip type of roofing whereas % have gable roofs while % have gable roofing style. the type of roofing affects the adoption of solar energy in two ways: first it affects the solar radiation to the next building; and second, it affects the solar radiation for the panels mounted on the roof. the angle of inclination of the roof affects the solar radiation if the angle of movement of the sun is not in consonance with the roof tilt angle. this has an effect on the energy output because according to [ ], at any location on the earth, solar output is affected by its tilt and azimuth angles. these angles play an important role in the efficiency of the solar photovoltaic panel (see figure ; figure ). figure . solar pv panels mounted over a hip roof. figure . solar panels mounted on the roof top of a bungalow house with a duplex house blocking the early morning sunrays from the east. the majority of the solar pv panels were placed on roofs, only about % of the respondents had their panels placed on the fence and open space within the perimeters of their buildings. although the sustainability , , of roof-top may not be the most suitable space for siting the panels due to unavailability of space, they have no option but to use the roof. according to a respondent: “if we have enough space, we would have mounted the panels on stake to serve as car shade, but due to lack of space, we had to mount it on the roof, yet the roof was not enough, so we had to mount some of the panels on the adjacent building,” . . decision-making issues in the management of solar pv by households the sustainability of clean energy produced at household level will certainly depend on the decision-making system that can determine how households use energy and maintain the installed system. decision-making may also entail what kind of appliances household members use or their energy efficiency labelling. for instance, % of the respondents indicated that by using solar pv they developed the culture of switching off appliances when not in use. however, households with many pv panels that generate energy for up to – h per day exhibited indifference to switching off their appliances. as a whole, adopters have to monitor their usage in order to maximize their back up time as well as maintain a healthy lifespan of the solar component. in this regard, one of the respondents argued that as a household: “we monitor our energy consumption, and once the battery backup remains %, we switch it off until the battery is charged again.” the nature of decisions taken by households to achieve efficient use of solar pvs is outlined in table . the timing of solar energy consumption appeared to be the leading strategy that households employ to tackle inefficient use by their members. table . measures for addressing inefficient usage. measures frequency percent timed usage . system upgrade . sensitisation light off none total . nevertheless, some users combine two measures to ensure maximum efficiency. the majority of the users prepared a timing for using the solar energy system. however, this is dictated by understanding and negotiating the use of the solar energy by the family members. for instance, a respondent observed that they had to “disconnect electric cooker from the distribution box, and now we rely gas cooker due to its lower cost and energy demand.” in this study, it was difficult to genuinely establish the efficiency of electric appliances in nigeria. this is due to poor standardisation, quality control lapses, and flooding of markets with imported counterfeit products. to overcome this, this study asked the respondents to categorise their home appliances that they plug in to solar energy. the breakdown of appliances is given in table . table . use of energy efficient appliances. perceived energy efficiency frequency percent poor . moderate good . total . despite the challenges of energy efficiency labelling in nigeria [ ], the majority of the observed households claimed to use appliances with good energy star labelling. they believed that their sustainability , , of appliances consume less energy. as a whole, appliances with low energy consumption tend to elongate the backup time as against appliances with high energy demand. over % of the solar pv adopters claimed that they changed their high energy appliances after installing the solar energy system. for instance, some respondents said they had to change all their lighting bulbs to energy saving bulbs. one of the respondents specifically noted that all their bulbs were replaced with watt bulbs and led lights for indoor lighting points. overall, the users were satisfied with the performance of their solar energy system, although % of the respondents expressed their dissatisfaction with the system. the majority of the respondents stated that they were satisfied because they got some relief from the incessant power outage. according to a female respondent: “my solar energy system is very satisfactory; this may not be unconnected with the high level of maintenance we carry out. it is being checked regularly by skilled personnel, even the liquid in the battery is gauged regularly.” nigeria depends largely on indian and chinese markets for its importation of solar panels, batteries and other accessories. as such, it can be said that nigeria’s transition to solar based renewable energy is foreign dependent. while dependency is not entirely a bad thing, some risks associated with global trade could jeopardise smooth transition to renewables. currently, over % of the users said spare parts and services were readily available through technicians who offer such services on request. at this point, it is important to stress that the solar business and maintenance services are informal and thrive within the broader urban informality. individuals lacking requisite training and knowledge of electric energy service can enter and join the solar energy business and its related services. one of the respondents related that: “i did my installation myself and have not done any repair, hence i don’t know of the availability of services and repairs.” this is a serious issue in that professionalism and safety issues are seriously compromised. . conclusions in this section, we draw many other insights from the results of the current study. renewable energy offers solutions to the current global energy crisis particularly as it relates to access and climate friendliness which the sdg propagates. this study outlines the stories of the adoption of solar pv technology by households in nigeria’s second largest urban agglomeration kano. by focussing on this city, the current study has broadened the narratives on the nature of transition to renewables in the informal urban areas in sub-saharan africa. as established by the literature, african households have the least access to energy and firewood has remained the main source of energy. hence, it is critical that all stakeholders drive actions for change and focus on mainstreaming sdg for households as units for measuring success of transitions to renewable energy. more so, the experiences of households living in informal urban settings are likely to improve our understanding of how poor and middle-income groups react to the energy crisis and the opportunities. in the case of nigeria—one of the world’s leading exporters of crude oil and natural gas—it is paradoxical that access to energy, in particular electricity, is poor. in a country where access to electricity by households is as low as four hours a day, there is a strong probability that energy insecurity could have negative ripple effects on the quality of life of urban households. however, more studies are needed to understand the situation as it affects people of rural areas. indeed, one of the limitations of the current study is its inability to pay much attention to age and gender dimensions of renewable energy technologies adoption and utilisation. this is definitely the next step to explore in a future study to understand households’ renewables utilisation dynamics. another area of interest for further studies is on the quality and efficiency of solar panels available to households. from the results of this study, it was revealed that none of the respondents uses solar energy for cooking. on the contrary, the literature has established that more than % of nigerian households rely on fuelwood for cooking. it is clear that most of the households use solar energy for lighting, cooling and other conveniences that support comfortable living. nonetheless, the limited capacity of the types of solar pvs available in nigeria makes it impossible for households to use them for cooking. sustainability , , of this technical limitation means solar energy adoption by households can hardly limit emission levels and the deforestation emanating from urban households’ massive dependency on fuelwood. this is another issue of interest to global and local players of the sdgs implementation. therefore, this point is considered critical that engineering and science, policy, development and civil society communities lever their collective actions for mainstreaming renewable energy transitions in developing countries. another insight from this study is in respect of the role of urban planning on the effectiveness of solar energy utilisation by households. it is apparent from the current study that siting of solar panels strongly depends on the nature of urban planning associated with neighbourhoods. in other words, the efficiency of the household solar energy system depends on the quality of the existing urban planning systems. in the case of this study, roofing systems and building types significantly affected exposure of solar pv panels to day-long sun rays. by implication, it is imperative for investors and the public sector to create and invest in initiatives to develop solar gardens that can generate electricity for individual urban households. in this way, the identified challenge can be addressed by solar energy sharing and sales to willing urban households. our study also highlights the critical role of the decision-making process on how households handle their clean energy sources and facilities. based on our findings, this is largely a behavioural issue that requires public enlightenment and can be supported by renewable energy associations. another issue of importance is to do with choices available to households with respect to energy labelling for energy efficient household appliances. energy regulatory authorities and standards organisations in developing countries need to develop robust strategies to address the importation of counterfeit appliances. finally, this study is optimistic that despite the challenges identified, the transition to clean energy security in africa is achievable. at least, the slow and steady running of renewables by households can make significant changes that support the process of implementing sdg . supplementary materials: the following are available online at http://www.mdpi.com/ - / / / /s . author contributions: a.h.a. undertook most aspects of the fieldwork under the guidance of a.s.b. a.-h.i.k. and a.h.a. conducted 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http://creativecommons.org/licenses/by/ . /. 	introduction 	materials and methods 	study area 	sampling of solar pv users 	sampling of the study sites 	procedure for data collection and analysis 	results and discussion 	analysis of how households use their solar pvs 	challenges to effective transition to solar pv energy 	decision-making issues in the management of solar pv by households 	conclusions 	references .qxp letter from the president mrs bulletin • volume • january • www.mrs.org/bulletin after i gave a talk here at los alamos last august on “our obligations toward the scientific community,” i received an e-mail from a postdoc: “interesting, fright- ening, and inspiring…” my talks have been called many things, but never “fright- ening” before—at least not to my face. i spoke about the global flow of four factors: energy, carbon, talent, and money. the trends in each are robust, and they predict the confluence of gigantic changes in the next years that could produce a frightening “perfect storm” in the human landscape. in this first letter of my presidency of the materials research society, i will out- line the compelling opportunity and unique obligations we as materials researchers have to help mitigate the storm damage. the national academies report “rising above the gathering storm” (www.nap.edu/catalog/ .html) gave rise to the opportunity, and we are obli- gated to rise to its challenge. energy and carbon flow are challeng- ing global issues. carbon-neutral energy is a must. just as th-century materials research underpins current energy tech- nologies, st-century materials research will underpin future energy technologies. thus, the materials community has a special role in the “perfect storm,” and the stakes are high. if our seas rise, the dis- placement of populations could be biblical. talent and money flow are national issues, but nations are necessarily linked. because it may take several nobel prizes to solve the problem of creating carbon- neutral energy, we need the full engage- ment of the world’s talent. poverty enor- mously depletes the talent pool, as does discrimination against women and minorities in many regions. even the united states, which has the resources and the obligation to make the largest contribution, falls short of potential because its talent is flowing away from science and engineering. our species has put itself in a fix. greater investment in physical sciences is a necessary first step. under proposed legislation in the united states, funding would double over five to seven years in key agencies for relatively little cost—less than research “earmarks” (pork) alone! this first step won’t happen or be sus- tained without our advocacy. the opportunity to double research funding is rare in the united states, europe, and asia but not unprecedented. u.s. funding for biosciences doubled over the last decade (figure ), leading to sub- stantial advances. physical sciences lag. the proposed legislation has unprecedent- ed bipartisan support; there are similar hopeful developments under the seventh framework programme in europe. indeed, science policies in washington, brussels, and beijing are linked. we are approaching a singularity in opportunity, and we cannot ignore it. i have challenged the society to double its advocacy efforts in support of funding increases and to challenge sister societies to do the same. mrs spends an average of $ (from all income sources) per member on advocacy, compared with $ per member for the american physical society. every mrs member, including non-u.s. members, can participate. sustained advocacy is needed if funding is to double. the mean lifetime for u.s. initiatives is only three years, and the un- realized doubling of the national science foundation budget ( – ) shows what can happen without long-term sup- port. through the international union of materials research societies (iumrs), our effort will link outside the united states. back to the postdoc. she wrote, “i am sincerely interested in helping to reduce the impact of the impending global energy crisis. i am not sure how to begin. some of the problems involving energy can be addressed through materials science and engineering. i would truly appreciate any suggestions and advice you could provide on how i, as an aspiring materials scien- tist, could make a difference.” this request for advice struck me pro- foundly. i replied weakly, “your obliga- tion, in my opinion, is to look for research opportunities and to get involved in advocacy,” and i promised a more com- plete answer later. over the next months, i will complete my response through these letters. upcoming topics include international linkage in science policy, strengthening our collective voice through recruitment, “open access” in publications to enhance information exchange, the society’s stance on energy materials research, talent lost in under- represented groups and to nontechnical fields, and the role of public outreach. we must seize the day. we can change history. the postdoc thanked me for my advice, writing, “i look forward to getting involved with advocacy in science, engi- neering, and technology. in the meantime, my husband and i plan to attack the grow- ing energy problem in a more personal way by adding a solar heater to our home. every little bit has to help.” alan j. hurd mrs president the gathering “perfect storm” it is up to us to make history “… st-century materials research will underpin future energy technologies.” figure . funding trends in federal research and development for selected agencies in fy – . source: american association for the advancement of science analyses of research and development in aaas reports viii–xxxi. fy figures are president’s request. r&d includes con- duct of r&d and r&d facilities. march revised © aaas. https://www.cambridge.org/core/terms. https://doi.org/ . /mrs . downloaded from https://www.cambridge.org/core. carnegie mellon university, on apr at : : , subject to the cambridge core terms of use, available at https://www.cambridge.org/core/terms https://doi.org/ . /mrs . https://www.cambridge.org/core asian survey, vol. , number , pp. – . issn - , electronic issn - x. © by the regents of the university of california. all rights reserved. please direct all requests for permis- sion to photocopy or reproduce article content through the university of california press’s rights and permissions website, http://www.ucpressjournals.com/reprintinfo.asp. doi: as. . . . . s u l f i k a r a m i r nuclear revival in post-suharto indonesia a b s t r ac t indonesia is planning to build a nuclear power plant to meet soaring demand for energy. opposing this policy, an anti-nuclear alliance is emerging from grassroots groups driven by distrust of the government’s ability to handle high-risk technology. this article explores the contemporary politics of indonesia’s nuclear power program. k e y w o r d s : nuclear power, post-suharto indonesia, anti-nuclear movement, energy crisis, democracy on june , , about , people gathered in downtown kudus in the district of jepara, central java. kudus means silent, but on that ex- traordinary day it was completely the opposite. a crowd of local residents, activists, artists, and students was fervently shouting, creating an uproar that shook the peaceful town. they all had come to express their firm rejection of jakarta’s plan to build four nuclear reactors in the muria peninsula on the north coast of central java. some demonstrators raised banners showing their con- demnation of what they saw as the government’s malicious ambition. an art performance by noted religious poet emha ainun najib animated the event. joining the protesters, interestingly, were public officials, district parliament members, military territorial commandants, and police chiefs. the district head of kudus even delivered a speech with a clear message that “[n]uclear power reactors should not be built in muria because the people do not want it.” the large-scale protest unfolding in the heartland of java was part of a series of adverse responses increasingly emerging from the grassroots level sulfikar amir is an assistant professor in the division of sociology, school of humanities and social sciences, nanyang technological university, singapore. this article stems from a research project funded by the school of humanities and social sciences, nanyang technological university. the author wishes to thank the reader for critical comments and inputs to an early version of this article. any errors in the article belong to the author. email: <sulfikar@ntu.edu.sg>. . “demo anti-pltn merambat ke kudus” [anti-nuclear protests spread to kudus], <http:// www.walhi.or.id/kampanye/energi/pltn/ _pltnkds_cu/>, accessed july , . as _ _amir.indd / / : pm • a s i a n s u r v e y : against nuclear energy, a form of technology that one indonesian non- governmental organization (ngo) calls “the destroyer of human future.” it all began almost one year earlier when minister of energy and mineral re- sources purnomo yusgiantoro announced indonesia’s plan to build a nuclear power plant to meet soaring demands for energy. as stated in kebijakan energi nasional (national energy policy, ken), conceived by the yudhoy- ono government in , indonesia expects to have a nuclear power plant within years. this represents the resurrection of an on-and-off program that has been around since the early s. after prolonged procrastination, this time the yudhoyono government determined that it was timely for in- donesia to go nuclear. badan tenaga nuklir nasional (national nuclear power agency, batan), a research agency under the ministry of research and technology, along with badan pengawas tenaga nuklir (nuclear regu- latory agency, bapeten), was given the responsibility for formulating a comprehensive plan for the nuclear power program. according to batan’s original roadmap, in the government was planning to invite foreign contractors to submit tenders for the construction of the muria plant, expected to commence in . the plant was scheduled to operate commercially by , yielding up to , mw of electricity in . the estimated cost for each megawatt is us$ million, to be covered by the designated contractor. parallel to the planning process, the state-owned perusahaan listrik negara (indonesian power company, pln) signed an agreement with korea electric power corporation (kepco) to conduct detailed studies of the location, regulations, safety, environmental impacts, and costs of the muria plant. it is assumed that nuclear-generated electricity costs will be less than . cents per kilowatt hour. in light of the resurrection of indonesia’s nuclear power program, which is concomitantly challenged by the anti-nuclear movement emerging from grassroots groups, this article seeks to explain the contemporary politics of nuclear power in indonesia. it sheds light on the juncture of several factors that have opened up the way for nuclear power to regain popularity. first, it highlights the political implications of the energy crisis that has heavily bur- dened president susilo bambang yudhoyono’s efforts to rekindle the indonesian economy and stabilize the popularity of his government. second, . see walhi’s (wahana lingkungan hidup indonesia) online publication, <http://www. walhi.or.id/kampanye/energi/pltn/ _pltn_cu/>, accessed july , . walhi is a leading environmental ngo relentlessly fighting against the implementation of nuclear power in indonesia. as _ _amir.indd / / : pm a m i r / i n d o n e s i a n u c l e a r • this study explores organized efforts by pro-nuclear bureaucrats to include the nuclear option in the national energy policy, with full support from vari- ous actors including politicians, private corporations, and international nu- clear agencies. last, this article observes the growing strength of the anti- nuclear movement that has arisen to respond to jakarta’s nuclear ambition. it argues that the rise of such an organized resistance by civil society groups is forged less by immediate fears of nuclear accidents than by distrust of the government’s ability to handle high risk technology. thus, this article points to fragile institutional conditions resulting from the democratic transitions indonesia has gone through since suharto’s departure in . this institu- tional precariousness appears to be a factor shaping society’s distrust of the government’s capacity to safely and securely produce nuclear power. e n e r g y p r e d i c a m e n t for years or so, oil was nothing less than nature’s blessing to indonesia. during its early period, the success of the new order government ( – ) led by president suharto in boosting the indonesian economy depended heavily on oil abundance. the state monopoly on oil production through the state-owned company pertamina gave suharto discretionary funds mostly used to build the power and prestige of his regime. thus, while a portion of oil revenues was spent to improve public sectors such as infrastructure and basic education, a larger bulk allocated through off-budget channels went to megaprojects, most notably the airplane manufacturing center in bandung, java. oil revenues also helped retain the military’s support suharto needed to keep his power intact. parallel to such political uses, from the outset su- harto subsidized the prices of oil products such as gasoline, kerosene, and diesel to keep them affordable for lower and middle class indonesians. this proved to be an effective policy to win the hearts of the majority. by the end of the new order period, oil turned into a curse as suharto’s expedient policy had created an oil-dependent society while indonesian oil production had begun to decline. furthermore, the misuse and mismanage- ment of oil-based resources under the monopoly of pertamina entailed severe . sulfikar amir, “nationalist rhetoric and technological development: the indonesian air- craft industry in the new order regime,” technology in society : ( ), pp. – . . william ascher, “from oil to timber: the political economy of off-budget development financing in indonesia,” indonesia ( ), pp. – . as _ _amir.indd / / : pm • a s i a n s u r v e y : inefficiency in almost every layer of energy production, distribution, and consumption. it was the oil dilemma that spurred the breakdown of the new order regime when the international monetary fund, in light of the asian financial crisis, came to compel suharto to withdraw oil subsidies. this deci- sion instantly sparked student protests around the country. in may , su- harto reluctantly stepped down following riots that broke out in jakarta and other big cities, killing hundreds of innocent people. in years to come, suharto’s legacy of a reckless energy policy left a consid- erable burden to his successors, both economically and politically. when the late president abdurrahman wahid signed the oil and gas law open- ing the oil business in indonesia to multinational corporations, pertamina was exposed to a competitive environment it had never encountered. in , the wahid government took a set of measures to improve pertamina’s efficiency and performance, but to many observers it was too late. by then the market was already liberalized, and multinational oil giants had pene- trated into the domestic market. in , indonesian politics saw the rise of yudhoyono, who came to power after outdoing the incumbent megawati sukarnoputri in the first di- rect presidential election. it took no time for yudhoyono to recognize crucial challenges he had to cope with in order to stay in office. an immediate di- lemma was a large portion of oil subsidies that burdened the state budget. the same problem haunted megawati, but she took no action to cut the oil subsidy, in an effort to avoid losing her popularity in the election. . in may , because of the indonesian constitution, suharto was replaced by his vice presi- dent, b. j. habibie, who became the third indonesian president, serving for less than two years. habibie attempted to extend his presidency but then cancelled his decision to run for president after his accountability speech was rejected by the majelis permusyawaratan rakyat (people’s con- sultative assembly, mpr). . james t. siegel, “early thoughts on the violence of may and , , in jakarta,” indonesia ( ), pp. – . . abdurrahman wahid was named the fourth indonesian president by mpr in october . wahid’s vice president was megawati sukarnoputri, daughter of the first indonesian president, sukarno, and chair of partai demokrasi indonesian perjuangan (indonesian democratic struggle party, pdip). in , wahid was impeached by the parliament due to corruption scandals and eventually replaced by megawati who completed the term in . . susilo bambang yudhoyono is a retired general who served as coordinating minister of poli- tics and security affairs in the megawati administration. a few months before he finished serving his term, he resigned from the cabinet and decided to run for president in the first direct presiden- tial election in . see r. william liddle and saiful mujani, “indonesia in : the rise of susilo bambang yudhoyono,” asian survey : ( ), pp. – . as _ _amir.indd / / : pm a m i r / i n d o n e s i a n u c l e a r • when yudhoyono started his administration, indonesia began to import more oil than it exported, making the subsidy unbearable. this rendered indonesia a net importer and consequently losing a membership in the organization of petroleum exporting countries (opec). it is instructive to have a brief look at indonesia’s energy consumption to understand the severity of its energy crisis. primary energy consumption dur- ing the past two decades grew at a relatively fast % per year. in , % of total energy consumed came from oil. nowadays, indonesia’s proven oil re- serves pump out around million barrels annually, but the reserves, accord- ing to expert predictions, will only last until . with no substantial efforts to find a substitute for fossil fuel, oil consumption is increasing rapidly, par- ticularly for transportation. dependency on oil, created by suharto’s regime, is also high in the electric power grid, contributing . % of the , . -mega- watt total installed capacity. caught up in this situation, importing oil is inevi- table for indonesia to keep meeting its soaring domestic demand for energy. only a few months after being formed, the yudhoyono government was slammed by the sudden rise of crude oil prices in the international market, which this time reached $ a barrel, while the state budget priced it at $ . that wide gap would have crippled the yudhoyono government with insol- vency if adjustments were not made immediately. thus, in march yudhoy ono decided to raise oil prices an average of %. by this action, the government saved us$ . billion in the state budget, a portion supposedly spent to subsidize oil products. not surprisingly, the hike sparked protests from the indonesian parliament, the dewan perwakilan rakyat (people’s representative council, dpr). a small group of opposition legislators who strongly wished to annul the new prices created an agenda to impeach yudhoy ono for his decision. fortunately for him, the attempt failed as vice president jusuf kalla, chair of the biggest party, golkar, signaled all parlia- ment members from his party to block the impeachment. . in may , the yudhoyono administration decided to withdraw indonesia’s membership in opec starting in . . golongan karya (golkar) was suharto’s ruling party. although it suffered a dramatic loss of votes in the election after suharto’s collapse, in the election golkar won % of parlia- ment seats. this helped yudhoyono to secure political support from the majority in the parliament, because his vice president was chair of the golkar party. for a historical account of golkar, see david reeve, golkar of indonesia: an alternative to the party system (oxford: oxford university press, ). for a contemporary account of golkar, see dirk tomsa, “party politics and the media in indonesia: creating a new dual identity for golkar,” contemporary southeast asia : ( ), pp. – . as _ _amir.indd / / : pm • a s i a n s u r v e y : in october , yudhoyono shocked indonesia by raising oil prices once more, by an average of %, the highest level ever in the country. “the government has gone too far!” wrote a noted economist who concurred with the necessity of raising oil prices but not to that extent. justification for the abrupt reduction of oil subsidies that consequently increased oil prices rested on the argument that oil subsidies, which absorbed nearly one-third of the state budget, were enjoyed mostly by the upper middle class in cities such as jakarta, bandung, and surabaya. there, energy consumption was many times higher than for those living under the poverty line. looking at this fact, the anti-subsidy economists in the government believed that oil subsi- dies had diverted the benefits of public funds that could otherwise be used to provide educational and health services for the poor. to lessen the consequent impact of this policy on those living in acute poverty, the yudhoyono administration launched a cash transfer program called bantuan langsung tunai (direct cash subsidy, blt) to compensate for sudden high inflation caused by the oil price hikes. this was in line with yudhoyono’s promise during his presidential campaign to alleviate poverty. however, the efforts to enact such a program earned yudhoyono and his economic team harsh criticism. as john farrington and rachel slater have shown, cash transfer policies can be ineffective because of complexity in administration and fund allocations. this was precisely the case when the yudhoyono administration distributed blt without prior experience. as a result, the blt program turned rampageous, as sloppy coordination provoked unnecessary conflicts between beneficiaries and local administra- tors. in the end, the poverty rate in indonesia remains high despite the blt program. . “pemerintah keterlaluan: kenaikan harga bbm melampaui kemampuan masyarakat” [the government has gone too far: the fuel price increase exceeds people’s ability], kompas (jakarta, indonesia), october , . . john farrington and rachel slater, “cash transfer: panacea for poverty reduction or money down the drain?” development policy review : (september ), pp. – . . lack of coordination in distribution of cash transfer resulted in riots in a few places driven by the disappointment of the people as to how the officials managed the program. even worse, a number of elders were killed from suffocation when queuing to collect the cash in the crowd. see “antrean dana bbm kembali menelan korban” [distribution of oil compensation cost more vic- tims], suara merdeka (semarang, indonesia), october , ; “pencairan dana blt di mulia rusuh” [cash transfer distribution in mulia ended up in riots], kompas cyber media (jakarta, indonesia), october , . as _ _amir.indd / / : pm a m i r / i n d o n e s i a n u c l e a r • the disturbing incidents staining the blt program damaged the popular- ity of yudhoyono’s leadership. this demonstrated some political implications of the energy predicament yudhoyono inherited from his predecessors. when the president started his term, his government faced many problems, from imminent deindustrialization and clumsy microeconomic progress to constant natural disasters, political violence, and social conflicts. however, it was the energy issue that practically posed the most serious threat to the longevity of yudhoyono’s presidency. a little tremor in the stability of the energy supply would produce a big wave of trouble, impacting almost every aspect of socioeconomic life. the dynamics of indonesia’s fragmented poli- tics after the demise of suharto’s authoritarianism made yudhoyono’s presi- dency vulnerable to political attacks from his opponents, most notably megawati sukarnoputri, who was eager to return to the presidential palace. although the yudhoyono leadership was completely legitimate when he took power through a fair and direct election, his legitimacy grew thin over time. it became evident that his administration had failed to take coordinated, effective action that could guarantee a sustainable supply of affordable en- ergy for domestic demand. the ruined image of the yudhoyono government worsened after the president reluctantly raised oil prices % in may when the international oil price struck $ a barrel. this was exacerbated by regular blackouts throughout java and bali caused by the limited capacity of pln, the sole electricity provider in indonesia. yudhoyono was by no means oblivious to the crisis plaguing indonesia’s en- ergy infrastructure. being a former minister of energy and mineral resources in the wahid administration (though for only a very short period), yudhoyono was keenly aware that the stability of energy security was crucial. many of his programs to revitalize industrial sectors depended on this stable energy flow, and the situation put his government at risk. success in sustaining energy provi- sion would probably boost his leverage for reelection in , but failure would definitely compromise his prospects. thus, the strategic option yudhoyono and his ministers determined to pursue was to curb overreliance on fossil fuels through energy diversification, exploiting different available resources. this opened up possibility for nuclear power to soon become part of the planned solution for the energy crisis, an opportunity instantly seized by nuclear advo- cates in indonesia. when yudhoyono successfully grabbed his second term in the presidential election, pro-nuclear groups remain confident that yu- dhoyono’s second administration will materialize the nuclear power program. as _ _amir.indd / / : pm • a s i a n s u r v e y : t h e n u c l e a r o p t i o n nuclear power is hardly new in indonesia. the country has been acquainted with nuclear research since the late s, when president sukarno, con- cerned about the radioactive fallout from u.s. thermonuclear weapons tests in the pacific, formed a commission on radioactivity research. tempted to acquire a nuclear capacity, sukarno created lembaga tenaga atom (institute of atomic energy, lta) in , which was later renamed badan tenaga atom nasional, which is now batan. a first research reactor was put to work in bandung as a result of assistance from the u.s.’s atoms for peace program in . for a short time, indonesia’s nuclear program turned po- litical: sukarno, inspired by china’s explosion of an atomic device in octo- ber , set off his own shock waves by announcing a plan to explode a nuclear weapon before the end of . the change of the political land- scape after suharto came to power in eventually tilted the nuclear pro- gram completely toward peaceful use. during the suharto regime, two other research reactors were added, a -kilowatt reactor in yogyakarta and a -megawatt facility in serpong, on the outskirts of jakarta. in addition, batan operates a cobalt radiator at the research facility in pasar jumat, jakarta, for agricultural purposes. since its inception, batan has continuously conducted applied research that produces a variety of isotopes useful for medical and agricultural pur- poses. but many batan researchers and officials have yearned for years to see a nuclear power plant erected in indonesia. the idea of producing nu- clear power in indonesia first surfaced in ; since then, a number of at- tempts were made to realize batan’s vision. a practical effort began in when the international atomic energy agency (iaea) assisted batan’s study of the feasibility of nuclear power in indonesia. however, for the next years, batan’s ambition to construct the first nuclear power plant in southeast asia never bore fruit. the first proposal sent to suharto in was rejected on the grounds that nuclear energy was not economically viable, given the limited capacity of the electricity grids. the second attempt took place in the late s after suharto gave a green . for an account of the early period of indonesia’s nuclear program, see daniel poneman, nuclear power in the developing world (london: allen and unwin, ). . an analysis on this turn of events is presented in robert m. cornejo, “when sukarno sought the bomb: indonesian nuclear aspirations in the mid- s,” the nonproliferation review (summer ), pp. – . as _ _amir.indd / / : pm a m i r / i n d o n e s i a n u c l e a r • light to batan. but to the dismay of batan officials, their proposal was once more turned down by suharto, for unclear reasons. at that point, there was no indication that suharto took nuclear power seriously. even b. j. habibie, later president but then minister of research and technology and suharto’s closest aide, who previously favored nuclear power, changed his mind, saying that nuclear power would be the last resort indonesia would need to pursue. despite this suspension, the planning of nuclear power development had been publicized and had sparked controversy lest the muria plant repeat the chernobyl disaster. fierce resistance came from abdurrahman wahid, then chair of nahdlatul ulama (nu), indonesia’s largest islamic organization, who pledged to undertake a hunger strike in muria were the nuclear plant to be constructed. batan could only hold back its proposal but continued to seek another chance. in february , dpr passed the nuclear power act, which led to the establishment of bapeten. a few months later, the asian financial crisis wiped out suharto’s political power and economic achievements. at this point, nuclear power remained a dream without clear prospects. after a few years in hiatus, the weakening of energy security that had imperiled the stability of post-suharto governments forged a renewed mo- mentum for batan to bring back the idea of building a nuclear power plant in muria. the planning for nuclear power in national policy after re- formasi (reform) was underway first reappeared in the ken conceived by the department of energy and mineral resources. in fact this had originated a few years earlier when then-iaea director-general mohamed elbaradei paid a visit to indonesia in december . elbaradei came person- ally to persuade then-president abdurrahman wahid to open up the possibility for the introduction of nuclear energy as an alternative source in the future. the director-general also promised that iaea would support financial and techni- cal efforts to study all potential resources for power generation in indonesia. . this proposal was conceived by the new japan engineering consultant (new jec) that won the bid to carry out the study covering multiple aspects of technology, safety, waste management, financing, operational management, and geological conditions. in the report, new jec advised indonesia to build units of mw reactors to be constructed in and to operate commer- cially in . . “antiklimaks nuklir muria” [anticlimax of muria’s nuclear plant], tempo (jakarta, indone- sia), january -february , . as _ _amir.indd / / : pm • a s i a n s u r v e y : eventually a study was produced entitled “comprehensive assessment of different energy sources” (cades). to the delight of batan, elbaradei’s lobbying worked well. a former strong opponent of nuclear power, this time wahid gave his blessing. jointly directed by batan and badan pengkajian dan penerapan teknologi (agency for assessment and application of technology, bppt), the cades project kicked off in to assess potential contributions of various energy options, taking into account key economic, social, and environmental fac- tors. participating in the project were the directorate-general of electricity and energy development (direktorat jenderal listrik dan pemanfaatan en- ergi, djlpe); directorate-general of oil and gas (direktorat jenderal min- yak dan gas bumi, djmigas); the environmental impact control agency (badan pengawasan dampak lingkungan, bapedal); the national statis- tics bureau (biro pusat statistik, bps); and pln. based on this list, the cades project seems to be the first initiative involving such a broad range of participants from which coordinated action could be expected. the study produced an overall estimate of energy production that indo- nesia needs immediately to secure its energy supply in the long run. the cades report covers different sources of energy, but its conclusion places an explicit emphasis on nuclear power. it says: “given the projected dynam- ics of indonesia’s energy system development, nuclear power becomes a com- petitive electricity generating option for indonesia some time between and .” thus, “a decision to move forward with nuclear power needs to be taken soon” and “a ‘go ahead decision’ is imminent.” in may , energy minister yusgiantoro signed ken, which laid out a comprehensive energy plan derived from the cades report. it is basically a revision of the kebijakan umum bidang energi (general policy on energy sector, kube). in this -page document, nuclear power is high- lighted as an economically competitive and environmentally friendly energy source indonesia must harness to sustain its electricity supply. to enforce . bakrie arbie, “status of nuclear power development in indonesia,” asia nuclear cooperation network newsletter, no. (march ), <http://www.fnca.mext.go.jp/english/newsletter/fnca_ news_no .pdf>, accessed july , . . “comprehensive assessment of different energy sources for electricity generation in indo- nesia” (jakarta, ). report prepared by a team of experts from indonesia with the guidance of iaea under the technical cooperation project ins/ / . . indonesian ministry of energy and natural resources, kebijakan energi nasional [national energy policy] (jakarta, ), pp. and . as _ _amir.indd / / : pm a m i r / i n d o n e s i a n u c l e a r • the implementation of ken, president yudhoyono issued presidential de- cree no. in january . the decree sets forth the so-called energy mix, a predetermined composition of different energy sources indonesia will uti- lize by : fossil fuel (less than %); natural gas ( %); coal ( %); biofuel ( %); geothermal ( %); new and renewable energy, including biomass, nu- clear, microhydro, solar, and wind ( %). as shown in these figures, nuclear power seems to hold only a tiny por- tion (slightly less than %) of the total energy supply through . how- ever, this is the first time nuclear power has been included in the national energy scenario, which gave batan more than enough impetus to regain confidence for turning its dream into reality. following up ken, batan formulated a road map consisting of several phases through which the nu- clear power program is to be realized. ownership designation and construc- tion bidding were scheduled to take place between and . the construction of the first reactor was targeted to commence in followed by the second in the following year. by , the first reactor was projected to be operating commercially, with the second in . the third will be started in followed by the fourth in . both will start operating commercially around . by then, the muria plant will be producing up to , megawatts of electricity, which counts over % of the whole energy demands across java and bali, which are predicted to reach approximately gw by . to tackle the safety and security aspects of nuclear production, in batan produced “guidance for the application and development of sustainable nuclear energy system in indonesia.” conforming to iaea regulations, this guidance defines basic principles and requirements of the nuclear system, taking into account such factors as economics, safety, en- vironment, waste, proliferation, and infrastructure. the guidance, accord- ing to batan officials, warrants the application of iaea’s universal nuclear safety standards to the muria plant. in addition, the development of a nu- clear emergency system is underway. once established, the system will be . batan, energi nuklir sebagai bagian dari sistem energi nasional jangka panjang [nuclear energy as part of national long-term energy system] (jakarta, ). . ibid., the guidance for the application and development of sustainable nuclear energy system in indonesia (jakarta, ), <http://www.batan.go.id/ref_utama/guidance_nes.pdf>, accessed july , . . interview with adiwardojo, jakarta, january , . as _ _amir.indd / / : pm • a s i a n s u r v e y : run by a cross-departmental task force involving the police, military, envi- ronmental protection, and the health ministry. g r o w i n g s u p p o r t one significant factor paving the path toward indonesian nuclearization comes from the global trend, which is witnessing a nuclear renaissance in many industrialized countries. nuclear power looms as a compelling option in today’s circumstances, which are marked by price fluctuations of oil com- modities on the international market and concerns over global warming. related to the former, the skyrocketing price of fossil fuel has hurt, rather than benefited, indonesia after it shifted to being a net oil importer, as dis- cussed above. such a situation provides batan with ammunition for going nuclear. although indonesia has only a limited supply of domestic uranium, expected to last less than years, nuclear advocates emphasize that the market price for this kind of fuel remains much lower and more stable than for oil commodities. this offers a high level of certainty for indonesia to maintain its energy security in the long run. in a situation where oil prices are remarkably high, a director of batan argues, “it would be financially strategic for indonesia to use low-cost nuclear power and sell its oil to other countries while the prices are high.” in a similar vein, escalating concerns over climate change bolster batan’s ammunition to press for nuclear power for indonesia. this goes hand-in-hand with yudhoyono’s commitment to minimize global warming. in this dis- course, nuclear power is claimed as one potential solution to lessen indone- sia’s production of carbon emissions. batan further argues that nuclear power can help indonesia to significantly reduce the greenhouse effect, im- proving the country’s image that was damaged by rampant forest fires in sumatera and kalimantan affecting neighboring singapore and malaysia. today, support for nuclear power from both the executive and legislative bodies is mounting. the ministry of research and technology (kemente- rian riset dan teknologi, ristek) and the ministry of energy and mineral . interview with as natio lasman, jakarta, february , . . adiwardojo interview. . for a detailed account of contemporary nuclear politics in indonesia, see sulfikar amir, “the state and the reactor: nuclear politics in post-suharto indonesia,” indonesia (april ). as _ _amir.indd / / : pm a m i r / i n d o n e s i a n u c l e a r • resources (kementerian energi dan sumber daya mineral, esdm) are playing pivotal roles in promoting the nuclear option. as approved by dpr, ristek allocated billion rupiahs ($ , ) for nuclear socialization pro- grams in alone. for the – period, the national development planning agency (badan perencanaan pembangunan nasional, bappe- nas) has allocated billion rupiahs ($ . million) for nuclear socializa- tion organized by batan. this is in addition to a budget of billion ru- piahs ($ . million) to be spent during the same period for preparing basic infrastructure documents meant to facilitate the nuclear power program. the socialization program is targeted to increase acceptance among local residents in jepara district, where the kudus demonstrations occurred, and also among influential religious figures. considering that the majority of the local community follows nu, ristek has been actively lobbying leading nu kyais (clerics) including its chair, hasyim muzadi. the ministry promises that the muria plant will meet high safety standards, and the local commu- nity will be the first to benefit from its operation. along with the socializa- tion program, at the technical level esdm has submitted to the president’s office a blueprint for a task force responsible for planning and overseeing the whole production process of indonesian nuclear power. once approved, this interdepartmental task force, comprising experts from related fields, is ex- pected to have the authority to determine the location, ownership, and finan- cial underpinning arranged for the future nuclear power plant. the conviction that it is timely for indonesia to go nuclear has also pen- etrated into parliament. this is a significant move, given the dpr’s political supremacy in public decisions in the post-suharto era. its commission vii, responsible for overseeing energy, technology, and environmental policies, has voiced its commitment to nuclear power and advised the yudhoyono government to mobilize necessary resources for the realization of the muria plant. despite dissenting voices by a few members of the commission, the majority believe indonesia has plunged into a chronic energy crisis and has no other long-term options immediately available. accordingly, the commission . bappenas, buku prioritas nasional rencana pembangunan jangka menengah nasional (rpjmn) – [book national priority of the national mid-term development planning, – ] (jakarta:  badan perencanaan pembangunan nasional, ). . interview with roosmalawati, jakarta, february , . . interview with evita legowo, jakarta, august , . as _ _amir.indd / / : pm • a s i a n s u r v e y : is urging the government to act so that nuclear power can be realized with- out evoking public resistance. economic factors are not alone in pushing realization of the nuclear proj- ect: nationalist sentiments fostered a strong commitment among pro-nuclear members of parliament to endorse the project. as one member of the com- mission revealed, the nuclear project is tightly linked to a desire to enhance national pride, something that he believes has been missing in recent years in indonesia. the presence of nuclear power, he argues, “will restore a shared feeling of nationalism that will unite the indonesian people.” such a view is shared by the wahid administration’s former minister of research and technology, a. s. hikam, also a parliament member from partai kebangki- tan bangsa (nation awakening party, pkb). serving on an expert panel on nuclear power, hikam encouraged the government “to put nuclear power at the top priority, for it is strategic to fulfill growing electricity demands but also a symbol of national pride.” responding to the whole process of nuclearization undertaken by his ad- ministration, president yudhoyono paid a visit to batan’s reactor in ser- pong on july , . in his speech before batan officials and journalists, yudhoyono remarked on the importance of nuclear research as a means to solve a wide range of problems overwhelming indonesia, ranging from the energy crisis to food production to global warming. although nuclear power itself was not explicitly mentioned, yudhoyono’s message signaled his com- mitment to batan’s efforts. finally, another element crucial to strengthening the move toward nucle- arization comes from private sectors. with % of the financing for the muria plant expected to derive from private investments, an indonesian leading energy company, medco energi, had decided to join this mega-proj- ect. medco fashioned a special unit, led by a former batan nuclear engi- neer, to deal with building the first reactor in muria. its first step, taken in , was reaching agreement with korean hydro and nuclear power (khnp) to carry out the project. . interview with tjatur sapto edy, jakarta, september , . . “activity report of expert committee on nuclear power, – ,” <http://www. batan. go.id/bp/extra/laporan% kegiatan% katn% .pdf>, accessed july , . . see yudhoyono’s speech at batan on july , , <http://www.presidensby.info/index. php/pidato/ / / / .html>, accessed july , . . interview with arnold y. soetrisnanto, jakarta, april , . as _ _amir.indd / / : pm a m i r / i n d o n e s i a n u c l e a r • s o c i e t y d i s t r u s t in spite of the full support the yudhoyono administration is giving to batan, and the regulatory preparations and safety system, public fear of nuclear disaster remains strong. the very fact that indonesia sits precisely on the “ring of fire,” an area of frequent earthquakes and volcanic eruptions encircling the pacific basin, raises concerns over the safety of the muria nu- clear plant. soedyartomo soentono, former chair of batan, argued that indonesia’s geological condition ought not to be a major issue for erecting a nuclear facility in java. he pointed to japan, which has operated its nu- clear reactors despite frequent earthquakes, as a model of safety indonesia could learn from, in particular when building “quake-friendly” nuclear reac- tors. however, the horrific image of the soviet union’s chernobyl nuclear disaster is frequently invoked by anti-nuclear activists and continues to preoccupy residents around the muria peninsula with visions of imminent catastrophe. to counter this sort of image, ristek initiated a socialization program aimed at increasing public acceptance of nuclear power through education and dialogue. this program has run into criticism by anti-nuclear activists, who say it emphasizes the benefits of nuclear power while concealing its great risks. from the activists’ point of view, fair socialization should cover both aspects so that local residents are informed and active, rather than being merely a passive audience for nuclear promotion. this critical point is valid. but a bigger error lies in the government’s ignoring public anxiety. the issue is not that people lack knowledge of nuclear, as assumed in the social- ization program. rather, they are perturbed that for the past few years, ja- karta has failed to build the capacity to provide secure public services. that the public doubts the ability of the government to control nuclear power safely is completely reasonable. indonesians are already frustrated by fre- quent disasters, both natural and manmade, that have killed many people and incurred vast economic losses. for instance, in recent years the indonesian public transport authority has accrued a notoriously high record of deadly ac- cidents. this reputation worsened with a series of accidents beginning in early . “pltn muria siap di bangun tahun ” [nuclear plant to be built in ], sinar hara- pan (semarang, indonesia), january , . . personal communication with adiwardojo, singapore, september , . . interview with nur hidayati, jakarta, february , . as _ _amir.indd / / : pm • a s i a n s u r v e y : . in addition to multiple airplane crashes, train derailments, and boat sinkings, the massive sidoarjo mudflow in eastern java exemplifies the gov- ernment’s failures in public safety. the human-caused disaster displaced thousands of sidoarjo residents and wasted millions of dollars on impotent measures aimed at halting the flow of hot mud. many observers question whether the government possesses the competence to manage high-risk technology. the bottom line is that post-suharto, the government has suffered from weakening capacity to exercise its authority, which, following joel migdal, is a weak state. harold crouch explains that the new order’s strong state relied not on institutional structure but on suharto’s patrimonial relations. the abrupt disappearance of his regime led to a rupture of the government’s capacity. in this light, two forms of government paralysis are very likely to cause flawed implementation of the nuclear program. the first is the acute . it started when the senopati boat carrying almost passengers sank in the java sea on new year’s eve of . the next morning, the privately owned adam air’s flight departing from surabaya to manado filled with passengers and six crew members was lost off the sulawesi island. the rescue team failed to discover the plane or passengers’ bodies and called off the search. a month later, the levina ferry caught on fire a few minutes after departing jakarta’s harbor, killing tens of people including three journalists who incautiously jumped into the boat to take a deep look just a moment before it sank. the worst happened when garuda, a government-owned airline with high safety records, crashed in yogyakarta, killing people on march , . . on may , , lapindo brantas, an oil company whose majority shares belonged to coordinating minister of people’s welfare aburizal bakrie, drilled a borehole in sidoarjo, east java. seeking to push down the cost, the company recklessly decided not to use a steel casing, which is needed to prevent potential circulation loss. consequently, when the drilling reached , feet down, it resulted in a blowout of hot mud. a number of technical solutions have been tried by lapindo to completely cover the well of the mudflow, but they all failed. after two years, hot mud continues to flow out, inundating several villages, highways, and train rails. a prediction says that the mudflow, popularly called lumpur lapindo (lapindo mud) after the company, is likely to last for another thirty years. to handle social and environmental impacts of the mudflow, yudhoyono formed a national task force responsible for resident relocation and environmental recovery. how- ever, after the team was dismissed, the appalling situation in the sidoarjo mudflow has not been handled completely. for an in-depth account of this tragedy, see jim schiller, anton lucas, and priyambudi sulistiyanto, “learning from the east java mudflow: disaster politics in indonesia,” indonesia (april ), pp. – . . joel s. migdal, “strong states, weak states: power and accommodation,” in state in society: studying how states and societies transform and constitute one another (cambridge: cambridge university press, ), pp. – . . harold crouch, “indonesia’s ‘strong’ state,” in weak and strong societies in asia-pacific societies, ed. peter dauvergne (canberra: allen and unwin, ), pp. – . . michael malley, “indonesia: the erosion of state capacity,” in state failure and state weak- ness in a time of terror, ed. robert rotberg (washington, d.c.: brookings institution press, ), pp. – . as _ _amir.indd / / : pm a m i r / i n d o n e s i a n u c l e a r • corruption that hinders the government from providing adequate public services. corruption is one factor that led the new order regime to its dra- matic end. however, the problem did not disappear, despite measures under- taken by the subsequent government to combat corruption. eradicating corruption is indeed one of the primary goals yudhoyono promised during his presidential campaign to accomplish. a few initiatives have been undertaken, including the establishment of tim koordinasi pemberantasan korupsi (coordination team for corruption eradication, tipikor) as complement to the existing komisi pemberantasan korupsi (commission for corruption eradication, kpk). numerous cases of corrup- tion have been brought to court, and many high-profile officials have been sent to jail, including several parliament members and university professors involved in election corruption. still, corruption remains pervasive. the yudhoyono government seems oblivious to the fact that the core problem is located not in individuals but in the bureaucratic system that lures and often forces officials to act corruptly. it is this very fact that haunts the nuclear program and threatens to make it defective. despite good facility management, as reported practiced at the batan reactors, success with a nuclear power plant on the muria peninsula requires the incorporation of a broader bureaucratic structure, a sociotechni- cal system that shores up the plant’s operation. a large portion of this socio- technical system—transmission networks, security systems, financial sup- port, and infrastructure sustainability—is beyond the authority of batan and bapeten. this means corruption will easily encroach into vulnerable areas, in time degrading safety and security and heightening the likelihood for nuclear mishaps to occur. no less alarming than corruption is the strife over authority between the central and local governments, a result of the decentralization underway as part of reformasi. derived from law / , created by the habibie admin- istration and enacted in , decentralization results in more detriments than benefits. a number of problems have emerged caused by poor capacity of local governments to take over authority from jakarta. this condition was inherited from the prolonged marginalization of local autonomy by . for analyses on efforts of corruption eradication in post-suharto indonesia, see natasha hamilton-hart, “anti-corruption strategies in indonesia,” bulletin of indonesian economic studies : ( ), pp. – ; stephen sherlock, “combating corruption in indonesia? the ombudsman and the assets auditing commission,” ibid., : ( ), pp. – . as _ _amir.indd / / : pm • a s i a n s u r v e y : suharto’s centralized government. among exemplars is the issue of acute malnutrition that afflicts several provinces, including southeast sulawesi, nusa tenggara barat, and nusa tenggara timur. this problem appeared after jakarta handed over the authority for public health care to local govern- ments whose resources were extremely limited. even worse, while intended to bestow autonomy on regional governments, decentralization in indonesia has been largely hijacked by predatory interests originating from the old re- gime that managed to reinvent themselves in the new democracy. rather than create more effective public administration at the local level, decentral- ization has spawned lucrative venues for local elites to profit by imposing levies on business activities and public services. consequently, the decen- tralization program is creating intense conflicts over resources between ja- karta and regional governments, as well as within local governments. the central government’s authority dwindles while local governments lack the capacity to handle complex technical systems. this creates a fragile context for any mega-project. the situation certainly threatens the nuclear program, a sophisticated, capital-intensive project requiring centralized con- trol to ensure the security and sustainability of a nuclear operation. unless this issue is settled, building a nuclear power plant in central java will be a daunting enterprise. it is the institutional precariousness illustrated above that overshadows in- donesia’s endeavor to establish its first nuclear power plant. thus, while nuclear power is steadily gaining currency among high officials and political elites in jakarta, it is simultaneously being contested by grassroots movements orga- nized by environmental activists and local anti-nuclear groups. two ngos fervently opposing nuclear power are walhi and greenpeace indonesia, both based in jakarta. members of these ngos are actively disseminating information on nuclear risks, using print media and the internet. they . syaikhu usman, “indonesia’s decentralization policy: initial experiences and emerging problems,” smeru working paper (september ). . “otonomi dan perut yang membusung” [autonomy and malnutrition], tempo (jakarta, indonesia), june – , . . vedi r. hadiz, “decentralization and democracy in indonesia: a critique of neo-institu- tionalist perspectives,” development and change : ( ), pp. – . . “wajah bopeng desentralisasi” [ugly face of decentralization], kompas (jakarta, indonesia), june , . . the internet has been an effective media for indonesian anti-nuclear groups to counter the promotion of nuclear power by the government. one of the websites is provided by walhi with regularly updated news on nuclear issues in indonesia and abroad. the website can be accessed at as _ _amir.indd / / : pm a m i r / i n d o n e s i a n u c l e a r • organize regular demonstrations to expose dangers inherent in nuclear en- ergy. they also call on the government to look for other renewable resources such as hydro and wind power, which they perceive as more appropriate solutions for the energy crisis. fighting locally is masyarakat rekso bumi (earth nurturing society), widely known as marem, an environmentally oriented organization founded and led by lilo sunaryo, who owns a hotel in jepara and holds a doctoral degree in power engineering. some financial support for local action has come from local businessmen, most notably djarum, a kudus-based major cigarette company whose owner feels threatened by the potential pres- ence of a nuclear power plant in muria. moral support for anti-nuclear movements comes from critical scientists such as iwan kurniawan, a former nuclear physicist at batan, and liek wilardjo, a physics professor at satya wacana christian university in salatiga whose writings rebuke the govern- ment’s decision to go nuclear. one shocking response to the nuclear con- troversy came from the religious leaders of nu in jepara, who in september declared that erecting a nuclear power plant on the muria peninsula would be considered haram (forbidden) according to islamic teachings. this is because construction would bring more mafsadah (harm) than maslahat (benefits) to local communities. anti-nuclear activists, scientists, religious leaders, and business persons, along with vote-pursuing local poli- ticians, together constitute an anti-nuclear alliance, the most solid ever seen seeking to challenge jakarta. they all share one stance: nuclear is not the answer! the anti-nuclear movement proved powerful in influencing yudhoyono in making a decision on the muria plant. this is evident in the prolonged delay of his approval to form a nuclear power task force. when esdm pro- posed the formation of the task force in , yudhoyono refused to approve <http://www.walhi.or.id/kampanye/energi/pltn>. another website is greenpeace indonesia acces- sible at <http://www.greenpeace.org/seasia/id>. . sulfikar amir, “challenging nuclear: anti-nuclear movements in post-authoritarian indo- nesia,” east asian science, technology, and society : – (september ), pp. – . . see, for example, liek wilardjo, “gegabah” [careless], kompas (jakarta, indonesia), june , . . nu leaders in jepara are strongly concerned with nuclear issues because nu adherents constitute a great majority of local residents in the muria peninsula. . “pcnu jepara: nuklir mubah, pltn haram” [pcnu jepara: nuclear is recommended, nuclear power plant is forbidden], september , , <http://www.nu.or.id/page.php?lang=id& menu=news_view&news_id= >, accessed october , . as _ _amir.indd / / : pm • a s i a n s u r v e y : immediately given the public uproar against nuclear power. obviously, at that time he did not want to risk his chance to secure a second presidential term considering his approval would instantly damage his popularity among voters in central java and the surroundings. but even after his landslide vic- tory in the presidential election, yudhoyono remains reluctant to pro- ceed further with the muria plant construction despite his favor for nuclear power. such a situation gives batan no options other than to postpone construction of the muria plant. consequently, batan’s nuclearization roadmap described earlier failed to meet the planned timetable, and the whole planning of the nuclear power program has been rescheduled accord- ingly. while waiting for favorable circumstances, batan also seeks to find another suitable area with less resistance. one potential site currently under consideration is along the northern coastline of banten province situated in the west end of java island. another possible scenario is to build nuclear power plants in kalimantan island. in a meeting with the yudhoyono ad- ministration, governors of east kalimantan and south kalimantan requested the government to have nuclear power plants constructed in their provinces due to severe lack of electricity in indonesia’s largest island. although this seems incongruent with the original objective of batan’s proposal, which is to provide electricity in java, the kalimantan scenario is not unlikely. with much less population density compared to java, rich natural endowment for economic development, and dire needs of electricity, kalimantan seems to offer a perfect location to establish indonesia’s first nuclear power plant. e p i l o g u e : d e m o c r at i z i n g n u c l e a r as described here, the aspiration for nuclear power in indonesia has been around for a long time. it dates back three decades and has survived. the persistence of indonesia’s nuclear program has been underpinned by a blend of institutional and ideological factors, working together intimately through the use of bureaucratic resources, scientific knowledge, and nationalist rheto- ric. in this light, it is important to focus a spotlight on the central role played . “pltn akan dibangun di pantura banten” [nuclear power plant to be constructed in northern coast of banten], kompas (jakarta, indonesia), august , . . anonymous interview with a government expert, jakarta, february , . . “kalimantan timur siap jadi lokasi pltn” [east kalimantan ready to host npp], koran tempo (jakarta, indonesia), february , . as _ _amir.indd / / : pm a m i r / i n d o n e s i a n u c l e a r • by batan, along with its sister agency bapeten, in continuously pro- moting the necessity for indonesia to harness nuclear power as a means to maintain energy security. for nuclear advocates in batan and other gov- ernmental agencies, going nuclear is not solely driven by a pragmatic agenda, to generate energy. for these advocates, nuclear bears some ideological mean- ing: embracing scientific progress as well as attaining national prestige. al- though such ideology is merely hinted at in the policy texts while pragmatic reasons get more emphasis, such ideological symbolism allows the desire for nuclear power to linger through three indonesian political regimes, from the ambitious sukarno, to authoritarian suharto, to democratic reformasi. the revival of nuclear power in the post-suharto era is signified by the emergence of two forces emanating from different spheres. the decline of indonesia’s fossil-fuel reserves is coupled with promising advances in nuclear reactor design; in addition, consolidation of efforts by nuclear promoters helps create new opportunities for nuclear power to attract decision makers. a stronger commitment of the yudhoyono government, itself a product of liberal democracy, helps to legitimize the inclusion of nuclear power in na- tional policy debates. yet, the same democratic context of the post-suharto era, guaranteeing freedom of speech and public protest, spurs anti-nuclear movements that are arising broadly across grassroots groups—without the specter of coercive suppression frequently practiced by suharto’s regime. thus, a striking feature in the post-suharto nuclear program is the contesta- tion of two equally powerful forces, the state-supported bureaucratic and technocratic elites versus the civil society alliance. each brings in different rationalities, paradigms, and interests. which side will prevail remains to be seen, but it is certain that the saga will cost both sides. this cost can be largely minimized if the yudhoyono government is willing to put its nuclear program under democratic control. such a move follows richard sclove’s suggestion: “if citizens ought to be empowered to participate in determining their society’s basic structure, and technologies are an important species of social structure, it follows that tech- nological design and practice should be democratized.” as a new democracy, indonesia is still learning to manage complex and sophisticated circumstances caused by fragmented politics after the demise of suharto’s authoritarianism. the nuclear controversy offers an opportunity for the state and civil society . richard sclove, democracy and technology (new york: guildford press, ), pp. – . as _ _amir.indd / / : pm • a s i a n s u r v e y : to settle their differences through a fair and equal political process toward agreement over how the nuclear program should be pursued. the participa- tion of local residents accompanied by impartial experts is important at every level of the decision-making process. benefits and risks should be broadly calculated and accurately communicated so decisions can be made. the gov- ernment is vulnerable because of the corruption and decentralized authority highlighted above. therefore, transparent dialogue and public accountability will be needed so that officials can develop the capacity to cope with the complexities of nuclear power, and to handle potential risks cautiously. as _ _amir.indd / / : pm consolidation studies of deltaic sediments: abstract; drilling funds and the energy crisis: abstract; significance of reservoir diagenetic alteration for petroleum exploration, gulf of alaska tertiary basin: abstract; depositional systems and oil-ga... association round table any interruption of our foreign energy supplies would have a dramatic effect on our economy and security and would show the dangerous results of the lack of a coherent and positive energy policy. there are very few discovered but undeveloped oil reserves in the u.s. except on the north slope, and those probably cannot be made available before . though the recent npc-aapg study indicates almost bilhon bbl of undiscovered but expectable recoverable u.s. reserves, any large increase in ex- ploratory effort to find them cannot have any great effect on our crude deficit before because of the necessary lead times. it is obvious, however, that certain steps can and should be taken immediately to encourage or to cause such an increase so that the period of danger to our economy and security will be as brief as possible. fitzgerald, d. m., and a. h. bouma, dept. oceanogra- phy, texas a&m univ., college station, tex. consolidation studies of deltaic sediments the texas colorado river delta, which built across mata- gorda bay between and , was selected for consolida- tion research. the objectives were to observe structural changes which occur wjien deltaic sediments undergo primary consoli- dation, and to correlate these consohdated sedimentary struc- tures with those reported from ancient deltaic environments. double cores were collected along a traverse parallel with the main river channel in the southeast lobe of the delta. one core was sput lengthwise, described, and radiographed. an analo- gous undisturbed section of the second core was then selected for consohdation. consolidation, through vertically compressing the sediments, partly creates new structures or makes poorly visible structures more discernible. it was noted in some cases that convolute laminations and recumbent folding formed after sections con- taining parallel laminations were consolidated. it was also ob- served that apparent homogeneous sections, after compaction, changed structurally to reveal parallel laminations. consequently, it should be realized that consolidation will aitect unconsolidated sediments and that these changes should be considered when comparing recent and ancient environ- ments. floyd, b. l., independent, portland, tex. drilling funds and the energy crisis (no abstract submitted) galloway, w. e., continental oil co., exploration re- search div., ponca city, okla. slcnihcance of r e s e r v o i r d i a g e n e t i c alteration for petroleum exploration, gulf of alaska tertiary basin the tertiary clastic section of the gulf of alaska sedimen- tary basin is considered an important potential future petro- leum province. considerable work in the onshore area has been carriesl out by industry preparatory to a projected sale of fed- eral leases on the continental shelf. examination of numerous samples collected from measured sections in oligocene to pleis- tocene strata has shown that the sandstones are mineralogically immature and unstable. diagenetic alteration of these potential reservoir sands at shallow to intermediate depths of burial has resulted in the ubiquitous formation of authigenie clay rims and coats around detrital grains and of poie-filling zeolite cements. these diagenetic alterations adversely affect both porosity and permeability and will provide a major limitation on the thick- ness of the sedimentary section than can be considered pros- pective. a compaction versus depth gradient, which is related to the sandstone porosity gradient, can be determined in off- shore areas by combination of seismically derived interval, velocity depth profiles, with a velocity-density calibration based on well data from the hecate strait (a geologically similar pacific margin basin lying off british columbia). the resultant density configuration can be cross checked by gravity modeling along the same seismic line. work on a line off cape yakataga shows that the prospective section is characterized by a high velocity and density gradient, indicating rapid loss of reservoir porosity with increasing depth of burial, as predicted by the onshore diagenetic model. semiquantitative evaluation of the compaction profile using the onshore reservoir data suggests that even in the youngest sections porosity decreases to less than % at depths of , to , ft. guevara, e. h., and r. garcia, bur. econ. geology, univ. of texas at austin, austin, tex. depositional systems and oil-gas reservoirs in queen city formation (eocene), texas regional surface and subsurface studies indicate that thick deltaic (queen city formation) and thin shelf (reklaw and weches formations) sequences compose the stratigraphic inter- val between the top of the wilcox group and the base of the sparta formation. in east texas, the queen city formation accumulated as part of a high-constructive, lobate delta system; and in south texas, as part of a high-destructive, wave-domi- nated delta system. in south texas, principal facies are mean- der-belt sand, lagoonal mud, stacked coastal barriers, and pro- delta-shelf mud facies; in east texas, delta plain, delta front, and prodelta facies are dominant; and in central texas, the principal facies are strandplain sands originated by southwest- ward longshore drift of sediments from the high-constructive delta system. facies distribution, composition, and size of the deltas in east texas are similar to lobes of the holocene high-construc- tive mississippi delta system and to ancient deltas in the lower part of the wilcox and in the jackson groups of the gulf coast basin. fluvial-deltaic sediments of south texas are comparable to pleistocene high-destructive wave-dominated facies on the surinam coast, to the holocene rhone delta system, and to ancient deltas in the upper part of the wilcox group. queen city deltas prograded gulfward over shelf muds and glauconites of the reklaw formation; they are overlain by comparable shelf facies of the weches formation. in east texas, deltaic facies wedge out eastward; terrigenous elastics of the high-destructive deltas extend southward into mexico. hydrocarbons are produced from thin strike-oriented sands downdip from the belt of maximum sand thickness of the high- destructive deltas in south texas; only a minor amount of oil and gas has been obtained from delta front and distributary channel sands of the high-constructive deltas in east texas. haas, m. w., vice-president for exploration, humble oil & refining co., houston, tex. petroleum exploration and environmental conservation u. s. faces energy crisis.—v. s. energy demands will nearly double by . all our principal sources of fuel will be needed to meet the demand; if domestic supplies cannot keep pace, we face increasing reliance on foreign oil. energy and public iands.—much of u. s. energy potential, including offshore oil and gas reserves, is on publicly owned lands. potentially productive acreage in the federal and state domain should be made available to industry in a manner designed to maximize timely development. environmental delays.—a principal factor in delaying explo- ration of frontier areas is environmental concern. many envi- ronmental objections are founded on the argument that oil and gas development is incompatible with other uses of the same land or water area. compatible use.—if exploration is to proceed at a pace con- sistent with national needs in the future, the concept of compat- ible multiple use of lands must be established as national pol- icy. industry must demonstrate from available examples that this concept is sound and results in maximum benefits to public and private interests. geologisls must contribute.—petroleum geologists should bring their knowledge to bear on public environmental issues and work for reasoned solutions based on scientific fact. much exploration today awaits public consent; geologists must aid in showing pubuc that energy-environmental problems can be - c - .fm communications to the editor bull. korean chem. soc. , vol. , no. http://dx.doi.org/ . /bkcs. . . . poly(acrylamide-co-acrylic acid) gel electrolytes for ni-zn secondary batteries sang-heon lee, keon kim,* and cheol-woo yi†,* department of chemistry, korea university, seoul - , korea. *e-mail: kkim@korea.ac.kr †department of chemistry and institute of basic science, sungshin women’s university, seoul - , korea *e-mail: cheolwoo@sungshin.ac.kr received november , , accepted december , key words : zinc anode, gel polymer electrolyte, ni-zn secondary battery, zn dendrite recently, there is growing concern about energy crisis and efficient controlling energy. the nickel-zinc (ni-zn) re- chargeable battery is the one of the most attractive power source for various electric devices and large-scaled energy storage systems because it has high specific energy density ( wh·kg− ), high specific power density, high open-cir- cuit voltage ( . v), low toxicity and so on. - despite all the advantages of ni-zn rechargeable battery, there are in- herent critical problems, such as zinc shape change, dendrite formation and high dissolution of the zinc electrode, arising from zinc electrode itself. , as a result, a zinc-based re- chargeable battery usually shows short cycle life, and it prevents the commercialization of zinc-based energy storage system. these problems for zinc-based system have grown serious as an increase in the number of charge/discharge cycles. in order to enhance the cell performance and over- come these problems originating from zinc redistribution and the solubility of zinc electrode in an alkaline medium, one of the possible ways is to use gel polymer electrolyte instead an alkaline solution. - several researchers demon- strated the enhanced cell performance and the suppression of zinc dendrite formation even if they also reported some disadvantages. - in the present study, the gel polymer elec- trolyte was prepared using poly(acrylamide-co-acrylic acid) (p(aam-co-aac)). the electrochemical performances of the ni-zn cell with the gel polymer electrolyte and the morphology of the zinc electrode during charge-discharge cycles were investigated. the anode (zn electrode) was prepared by pasting a mixture consisting of the pristine or modified zno powder ( wt %), ketjen black (kb; wt %), ca(oh) ( wt %), bi o ( wt %), and polytetrafluoroethylene (ptfe; wt %) on a porous ni foam. the addition of ca(oh) reduces the shape change of the zinc electrode and improves the cycle stability of the ni-zn batteries, and bi o suppresses the hydrogen evolution. the electrode was dried at oc and pressed ( kgf·cm− ) to a thickness of ~ . mm. the ni electrode consists of ni(oh) powder ( wt %), ni powder ( wt %), co(oh) ( wt %), polyethylene (pe; wt %), and ptfe ( wt %). it has been reported that the addition of cobalt to the active material improves the reversibility of the electrochemical reaction. the standard electrolyte is an aqueous solution consisting of . m koh, . m naoh, and . m lioh because this composition has a maximum ionic conductivity and suppresses the shape change of zinc electrode. , the gel polymer electrolyte was prepared by the following steps. p(aam-co-aac) was added to alkaline solution, and the mixture was stirred until they form a homo- geneous solution. then, the solution was poured onto an airtight glass vessel to avoid water evaporation and absorp- tion of carbon dioxide. the conductivities of gel polymer electrolyte and normal alkaline electrolyte were measured by im impedance analyzer (zahner elcktrik). the morpho- logies of zno electrode and the microstructure of zno powders were investigated by field emission scanning elect- ron microscopy (fe-sem, hitachi s- , japan) with energy dispersive spectroscopy (eds, horiba ex- ). the electrochemical performances of the various compounds were evaluated using a wbcs instrument (wona tech., korea). the three-step charge regime , from samsung advanced institute of technology was used and the discharge rates were . c (until the rd cycle) and . c (after the rd cycle). the gel polymer electrolyte is a viscous liquid mixture. as increase in the concentration of p(aam-co-aac) the vis- cosity of the electrolyte increases. the conductivity of the gel polymer electrolytes as a function of the concentration of p(aam-co-aac) was measured at room temperature. the ionic conductivity of gel polymer electrolyte slightly de- creases with an increase in the concentration of p(aam-co- aac). considering the conductivity and the viscosity of the gel polymer electrolyte, the concentration of p(aam-co- aac) is fixed to wt % and the conductivity is . × − s·cm− . the discharge capacities of ni-zn cells with normal alkaline electrolyte and gel polymer electrolyte as a function of the number of charge-discharge cycles are presented in figure . for a normal alkaline electrolyte, the discharge capacity rapidly decreases with increasing number of charge- discharge cycles. at cycles, the retention ratio of dis- charge capacity is ~ % ( mah·g− ). this is the typical phenomenon of ordinary ni-zn cells due to the formation of dendrite, shape change, and dissolution of zinc electrode. on the contrary, the initial discharge capacity of cell with the gel polymer electrolyte is above mah·g− after activation up to cycles, and then gradually decreases with increasing number of cycles. the capacity retention of cell is ~ % at cycles ( mah·g− ) and remarkably increases in com- bull. korean chem. soc. , vol. , no. communications to the editor parison with that with a normal alkaline electrolyte. it is reported that polymer electrolytes are expected to be less reactive than liquid electrolyte and the use of polymer electrolyte can suppress the problem of dendrite growth. - in addition, gel polymer electrolyte can reduce the zinc dis- solution in an alkaline medium in ni-zn secondary battery. the morphology of zinc electrode in the two electrolyte media after charge-discharge tests was investigated by sem as shown in figure . after the charging-discharging test, the zinc electrode was washed in distilled water, rinsed with ethanol and then dried. the initial morphology of the pri- stine zno has a characteristic hexagonal prismatic shape with a smooth surface as shown in figure (a). as we expected, the severe dendrite formation is observed on the cell with a normal alkaline electrolyte after cycles of charging-discharging as shown in figure (b). the zn den- drite easily penetrates into the separator and results in an interior short circuit. however, figure (c) and (d) show the morphology of the zinc electrode with the gel polymer electrolyte after and charge-discharge cycles, respec- tively. the morphology of the zinc electrode with the gel polymer electrolyte was not changed much after the charge- discharge cycles. only the difference is that particle size slightly increases with increasing number of charge-discharge cycles. it is demonstrated that the gel polymer electrolyte effectively suppresses dendrite formation. in summary, the gel polymer electrolyte has high ionic conductivity of good mechanical stability. the ni-zn cell with gel polymer electrolyte shows good charge-discharge characteristics and suppresses the shape change of the zinc electrode. the gel polymer electrolyte, p(aam-co-aac), is considered as a promising candidate for applications in rechargeable zinc-based rechargeable battery systems. acknowledgments. this work was supported by the sungshin women's university un-jeong global project re- search grant of . references . jindra, j. j. power sources , , . . jindra, j. j. power sources , , . . ma, m.; tu, j. p.; yuan, y. f.; wang, x. l.; li, k. f.; mao, f.; zeng, z. y. j. power sources , , . . yuan, y. f.; tu, j. p.; wu, h. m.; yang, y. z.; shi, d. q.; zhao, x. b. electrochim. acta , , . . lee, s.-h.; yi, c.-w.; kim, k. j. phys. chem. c , , . . zhu, j.; zhou, y. j. power sources , , . . iwakura, c.; nohara, s.; furukawa, n.; inoue, h. solid state ionics , , . . kumar, g. g.; sampath, s. solid state ionics , , . . fauvarque, j. f.; guinot, s.; bouzir, n.; salmon, e.; penneau, j. f. electrochim. acta , , . . mohamad, a. a.; mohamed, n. s.; yahya, m. z. a.; othman, r.; ramesh, s.; alias, y.; arof, a. k. solid state ionics , , . . yang, h.; meng, x.; yang, e.; wang, x.; zhou, z. j. electrochem. soc. , , a . . jain, r.; a, t. c.; mclarnon, f. r.; cairns, e. j. j. appl. electrochem. , , . . geng, m.; northwood, d. o. int. j. hydrogen energ. , , . . gagnon, e. g. j. electrochem. soc. , , . . renuka, a.; veluchamy, a.; venkatakrishnan, n. j. power sources , , . figure . discharge capacities of ni-zn cells with the normal alkaline and p(aam-co-aac) gel polymer electrolytes. figure . sem images of (a) pristine zno electrode, (b) after cycles with a normal alkaline electrolyte, (c) after cycles with a gel polymer electrolyte, and (d) after cycles with a gel polymer electrolyte. research on pv/t – air source heat pump integrated heating system in severe cold region procedia engineering ( ) – - © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of cchvac doi: . /j.proeng. . . sciencedirect available online at www.sciencedirect.com th international cold climate hvac conference, cchvac research on pv/t—air source heat pump integrated heating system in severe cold region chihong cao, huixing li, guohui feng*, ran zhang and kailiang huang school of municipal and environmental engineering, shenyang jianzhu university, shenyang , china abstract photovoltaic-thermal (pv/t) technique is applied to air source heat pump (ashp) heating system in severe cold region, which can achieve high efficient heating of ashp in low-temperature environment and maximize the utilization of renewable energy. the using limitations and common problems of ashp heating system in severe cold region is studied in this paper. based on the solar radiation heat transfer mechanism and characteristic of air--heat transfer media, pv/t--ashp integrated heating system is developed. trnsys transient simulation software was used to study the integrated heating system. through the simulation analysis, the outlet temperature of pv/t collector can reach . and the average cop of ashp unit reaches . , which improves the heating efficiency of ashp and provides a new idea for the future heating mode in severe cold region. © the authors. published by elsevier ltd. peer-review under responsibility of the organizing committee of cchvac . keywords: pv/t; air-source heat pump; cop; trnsys . introduction with the outbreak of the global energy crisis and the environmental problem is becoming more and more prominent, people seek for the efficient method of utilizing renewable energy to replace the traditional energy. as a clean and renewable energy, solar energy is the most abundant resources human can make use of. moreover, there is no transportation problem in development and utilization or negative impact on the ecological environment. therefore, vigorously promoting the use of solar energy applying in hvac field is a hot issue in recent years. it is * corresponding author. tel.: + - ; fax: + - - . e-mail address: fengguohui @ .com © the authors. published by elsevier ltd. this is an open access article under the cc by-nc-nd license (http://creativecommons.org/licenses/by-nc-nd/ . /). peer-review under responsibility of the organizing committee of cchvac http://crossmark.crossref.org/dialog/?doi= . /j.proeng. . . &domain=pdf chihong cao et al. / procedia engineering ( ) – also an important measure to reduce building energy consumption, as well as a main tool to solve the energy crisis and environmental problems. the solar energy resources are very rich in our country. the annual amount of solar radiation in more than % of the area is higher than mj/m , and the annual sunshine duration is greater than h, which makes the development and utilization of solar energy considerable prospect. over the past ten years, due to the efficiency of photovoltaic cells and solar collector efficiency increased, the pv/t technique develops rapidly, which is used in building and hvac fields more and more widely. the core of pv/t technique is a photovoltaic-thermal collector, which is combined with photovoltaic cell and solar heat collector by lamination or adhesive technology (kern ). in the absorption process, about % of long wave radiation energy of the heat collecting plate converts into heat, and surface temperature of heat plate increases up to ~ . the remaining % of the solar radiation energy converts into electrical energy. pv/t technique used in building has the following advantages, such as good thermoelectric effect profit, obvious energy saving effect, long service life and so on. agrawal studied a photovoltaic-thermal building integrated system, which concluded that the system initial investment compared to the individual collectors and photovoltaic building wall was higher than about ~ %, but the cost of power generation decreased by ~ %, the overall system energy efficiency increased ~ % (agrawal ). the design and application of pv/t technique in building has been more mature. some countries have carried out the performance parameter test in experimental models of the construction, and gradually applied to the actual construction. ashp system is environmental friendly, low energy consumption, in relatively stable performance, huge in energy-saving potential and good in social benefits. all the above advantages promotes its rapid development in china. however, in the application process we found that it affected by conditions of the outdoor environment and climate is relatively large. when under the low temperature environment in cold region, the heating capacity is relatively low, which cannot fulfil the requirements of building heating in winter. with the outdoor environment temperature decreased, the unit cop decreases gradually and the compressor pressure ratio will increase which leads to an increase in exhaust gas temperature and damage to the compressor in long-term operation, which confines large-scale popularization and application in our country. in order to improve the universality of application and strengthen thermal performance of the thermal system in low temperature environment of ashp, it is mainly by improving the performance of heating cycle of component, optimizing the control system of thermal cycling system, controlling exhaust temperature of the unit, using the new refrigerant, improving the defrosting technical measures and so on. on the improvement of air source heat pump heating system in low temperature environment, foreign researchers have done a lot of researches. nobukatsu put forward a kind of economizer gas injection system with scroll compressor, which heat capacity can be increased by % running in low temperature environment (nobukatsu ). sami transfered traditional refrigerant into non azeotropic refrigerant to improving the thermal performance heat pump system in low temperature environment (sami ). the above measures can improve the thermal performance of ashp system in low temperature environment. however, there are strictly technical requirements in the optimization design of heat pump units, the system efficiency is still low, and frost technology has not completely been overcome. for the current technical level, it is difficult to widely promote the use of ashp in cold region. therefore, a new application mode of ashp system is put forward in this paper. based on the traditional ashp system, photovoltaic-thermal technique is integrated with it, which improves the efficiency of ashp using in low temperature environment and solves the problems when applying in cold region. . methods based on the advantages of photovoltaic-thermal technology and the difficulties of ashp using in low temperature environment in the practical application, a pv/t-ashp integrated heating system is developed, which can operate safely, stably and efficiently in winter in cold region. figure shows the schematic diagram of pv/t— ashp integrated heating system. pv/t air collectors were arrayed on the building envelop composing an integrated pv/t curtain wall. in the pv/t, up and down sides are respectively opened outlets and inlets connected to the ashp unit with air ducts forming a forced circulation in the system. air as the medium absorbing the waste heat of pv/t cavity, and the heat pump can utilize this part of heat. by using the pv/t air collector heating the circulated air, it can avoid the deterioration of heat transfer effect and performance drop of unit due to the evaporator frosting when chihong cao et al. / procedia engineering ( ) – the ashp operating in low temperature. besides, there is almost no overheating during the energy transfer process, freezing, boiling, corrosion and leakage problems are not to be considered in the practical application. the maintenance cost of the air collector is lower than the liquid one. fig. . pv/t—ashp system schematic diagram. . trnsys simulation trnsys software, developed by solar energy laboratory of university of wisconsin-madison, is a dynamic simulation software. the biggest feature is the modular analysis in the software. it is considered to be one of the most flexible simulation software, we can use the modules easily to build up a variety of complex system. in this study, the pv/t-ashp integrated heating system was built by the trnsys showed in figure , which mainly studies the outlet temperature of the pv/t collector and the cop of the ashp unit and explores the feasibility of the system using in severe cold region. using the climate module in trnsys to calculate the ambient temperature of the pv/t collector during the heating period from november to march based on the shenyang typical meteorological data. the pv/t air collector was a m× m large scale apparatus integrated with building envelop. rated heating power of the ashp unit was . kw and the rated air flow of the fan is m /h. a m phase change storage water tank was used to store heat water prepared from the ashp unit, and the outlet temperature of the unit is set to be . the control scheme of the system was based on the load profile. simulation time step was set to be . h, tolerance integration and convergence were both . . fig. . trnsys project of pv/t—ashp integrated system. chihong cao et al. / procedia engineering ( ) – . results as it shown in figure , the outlet temperature of the pv/t collector varied widely ranged from - . to . during the heating period in shenyang. the operating scheme of the pv/t collector is when the outlet temperature of pv/t collector is higher than the bottom temperature of water tank from to in the daytime, the fan then will run, and the ashp system will produce heat water. through the picture, we know that during the heating period the outlet temperature of pv/t collector is low when no solar radiation. however, when the pv/t collector was subjecting from solar radiation, the outlet temperature of pv/t collector increases marginally, which can directly supply to the ashp unit for heating. meanwhile, some cop data were also obtained from the trnsys software showed in figure . the cop of the ashp unit varied from . to . , which changes depending on the outlet temperature of pv/t collector accordingly. in most of the time, ashp unit operates in a relatively high efficiency condition and the average cop can reach . . fig. . outlet temperature of the pv/t collector. fig. . cop of the ashp unit. chihong cao et al. / procedia engineering ( ) – . discussion through the simulation, it concludes that the pv/t--ashp integrated heating system can effectively increase the cop of the ashp unit when the outdoor temperature is low. theoretically, it can supply part of energy to a building with the solar energy, a sort of non-continuous energy source. however, there still some researches need to be taken. due to the pv/t collector is affected by random factors such as weather, the fluctuation of heat is huge. without auxiliary heat source, the integrated system cannot achieve heating stably and continuously. the outlet temperature of phase change water tank is not studied in this research. besides, only on type pv/t collector was used in the study, there should be several kind of collectors compared to find out the most suitable one. . conclusions in the context of energy-saving and emission reduction, vigorously promoting the use of renewable energy replacing traditional fossil fuels has become one of the main measure to deal with the energy crisis and environment problem. there are a lots of advantages of pv/t and ashp technology, they should be popularized in the engineering. however, due to the existing technical level, the use of large-scale pv/t collector has a series of problems, such as higher initial investment, longer recovery cycle, low system efficiency, easily suffering from the outdoor environment, which restricts the development in our country. in this paper, according to the operation condition of ashp system in severe cold area and the application characteristics of pv/t technique, a pv/t-ashp integrated heating system is developed. trnsys transient simulation software was used to study the outlet temperature of pv/t collector and the cop of ashp unit during a heating period in shenyang. through the simulation analysis, the outlet temperature of pv/t collector can reach . and the average cop of ashp unit reaches . . through this integrated system, we hope to provide some new ideas for popularizing the use of ashp and pv/t technology in severe cold region. acknowledgements the work is supported by the national science and technology infrastructure program (no. baj b - ). references [ ] kern e. c. russell m. c. combined photovoltaic and thermal hybrid collector system. presented at th ieee photovoltaic specialists conference, washington, dc, june - , , - . 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